Holding manipulator and synthesizing

Holding manipulator and synthesizing

Precision metalparts Holding manipulator and synthesizing the robot research and development condition in recent years, a economic scheme is concluded on the basis of the analysis of mechanical configuration, transform system, drive device and control system and guided by the idea of the characteristic and complex of mechanical configuration, electronic, software and hardware. In this article, the mechanical configuration combines the character of direction coordinate which can improve the stability and operation flexibility of the system. The main function of the transmission mechanism is to transmit power to implement department and complete the necessary movement. In this transmission structure, the screw transmission mechanism transmits the rotary motion into linear motion. Worm gear can give vary transmission ratio. Both of the transmission mechanisms have a characteristic of compact structure. The design of drive system often is limited by the environment condition and the factor of cost and technical lever. The step motor can receive digital signal directly and has the ability to response outer environment immediately and has no accumulation error, Precisionmetal parts which often is used in driving system. In this driving system, open-loop control system is composed of stepping motor, which can satisfy the demand not only for control precision but also for the target of economic and practicality. On this basis, the analysis of stepping motor in power calculating and style selecting is also given. The analysis of kinematics and dynamics for object holding manipulator is given in completing the design of mechanical structure and drive system.

 Current industrial approaches Precision metal parts to robot arm control treat each joint of the robot arm as a simple joint servomechanism. The servomechanism approach models the varying dynamics of a manipulator inadequately because it neglects the motion and configuration of the whole arm mechanism. These changes in the parameters of the controlled system sometimes are significant enough to render conventional feedback control strategies ineffective. The result is reduced servo response speed and damping, limiting the precision and speed of the end-effecter and making it appropriate only for limited-precision tasks. Manipulators controlled in this manner move at slow speeds with unnecessary vibrations. Any significant performance gain in this and other areas of robot arm control require the consideration of more efficient dynamic models, sophisticated control approaches, and the use of dedicated computer architectures and parallel processing techniques.

  

About Modenr Industrial Manipulayor

About Modenr Industrial Manipulayor

 Robot is a type of  cnc turnining mechantronics equipment which synthesizes the last research achievement of engine and precision engine, micro-electronics and computer, automation control and drive, sensor and message dispose and artificial intelligence and so on. With the development of economic and the demand for automation control, robot technology is developed quickly and all types of the robots products are come into being. The practicality use of robot not only solves the problems which are difficult to operate for human being, but also advances the industrial automation program. Modern industrial robots are true marvels of engineering. A robot the size of a person can easily carry a load over one hundred pounds and move it very quickly with a repeatability of 0.006inches. Furthermore these robots can do that 24hours a day for years on end with no failures whatsoever. Though they are reprogrammable, in many applications they are programmed once and then repeat that exact same task for years.

  At present, cnc turnining the research and development of robot involves several kinds of technology and the robot system configuration is so complex that the cost at large is high which to a certain extent limit the robot abroad use. To development economic practicality and high reliability robot system will be value to robot social application and economy development. With he rapid progress with the control economy and expanding of the modern cities, the let of sewage is increasing quickly; with the development of modern technology and the enhancement of consciousness about environment reserve, more and more people realized the importance and urgent of sewage disposal. Active bacteria method is an effective technique for sewage disposal. The abundance requirement for lacunaris plastic makes it is a consequent for plastic producing with automation and high productivity. Therefore, cnc turnining it is very necessary to design a manipulator that can automatically fulfill the plastic holding. With the analysis of the problems in the design of the plastic 。

Quenching&annealing and Tempering’s different

Quenching&annealing and Tempering’s different

When the term “annealing” is applied to ferrous alloys without qualification, full annealing is applied. Precision metal parts This is achieved by heating above the alloy’s transformation temperature, then applying a cooling cycle which provides maximum softness. This cycle may vary widely, depending on composition and characteristics of the specific alloy.

   Quenching is a rapid cooling of a steel or alloy from the austenitizing temperature by immersing the workpiece in a liquid or gaseous medium. Quenching medium commonly used include water, 5% brine, 5% caustic in an aqueous solution, oil, polymer solutions, or gas (usually air or nitrogen).

  Selection of a quenching medium depends largely on the hardenability of material and the mass of the material being treating (principally section thickness).

  Precision metal parts The cooling capabilities of the above-listed quenching media vary greatly. In selecting a quenching medium, it is best to avoid a solution that has more cooling power than is needed to achieve the results, thus minimizing the possibility of cracking and warp of the parts being treated. Modifications of the term quenching include direct quenching, fog quenching, hot quenching, interrupted quenching, selective quenching, spray quenching, and time quenching.

  Tempering. Precision metal parts In heat treating of ferrous alloys, tempering consists of reheating the austenitized and quench-hardened steel or iron to some preselected temperature that is below the lower transformation temperature (generally below 1300 ℃ or 705 ℃). Tempering offers a means of obtaining various combinations of mechanical properties. Tempering temperatures used for hardened steels are often no higher than 300 ℃(150 ℃). The term “tempering” should not be confused with either process annealing or stress relieving. Even though time and temperature cycles for the three processes may be the same, the conditions of the materials being processed and the objectives may be different.

 

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Classification of Heat Treating Processes

Classification of Heat Treating Processes

 Precision CNC machining parts In some instances，heat treatment procedures are clear-cut in terms of technique and application．whereas in other instances，descriptions or simple explanations are insufficient because the same technique frequently may be used to obtain different objectives．For example, stress relieving and tempering are often accomplished with the same equipment and by use of identical time and temperature cycles．The objectives，however，are different for the two processes．

 The following descriptions of the principal heat treating processes are generally arranged according to their interrelationships．

 Normalizing consists of heating a ferrous alloy to a suitable temperature (usually 50°F to 100°F or 28℃ to 56℃) above its specific upper transformation temperature．This is followed by cooling in still air to at least some temperature well below its transformation temperature range．For low-carbon steels, the resulting structure and properties are the same as those achieved by full annealing；for most ferrous alloys, normalizing and annealing are not synonymous.

 Precision CNC machining parts  Normalizing usually is used as a conditioning treatment, notably for refining the grains of steels that have been subjected to high temperatures for forging or other hot working operations. The normalizing process usually is succeeded by another heat treating operation such as austenitizing for hardening, annealing, or tempering.

  Precision CNC machining parts Annealing is a generic term denoting a heat treatment that consists of heating to and holding at a suitable temperature followed by cooling at a suitable rate. It is used primarily to soften metallic materials, but also to simultaneously produce desired changes in other properties or in microstructure. The purpose of such changes may be, but is not confined to, improvement of machinability, facilitation of cold work (known as in-process annealing), improvement of mechanical or electrical properties, or to increase dimensional stability. When applied solely to relive stresses, it commonly is called stress-relief annealing, synonymous with stress relieving.

    

Heat treatment of metal

Heat treatment of metal 

  Precision CNC machining parts The generally accepted definition for heat treating metals and metal alloys is “heating and cooling a solid metal or alloy in a way so as to obtain specific conditions or properties.” Heating for the sole purpose of hot working (as in forging operations) is excluded from this definition．Likewise，the types of heat treatment that are sometimes used for products such as glass or plastics are also excluded from coverage by this definition．

 Transformation Curves 

 Precision CNC machining parts The basis for heat treatment is the time-temperature-transformation curves or TTT curves where，in a single diagram all the three parameters are plotted．Because of the shape of the curves，they are also sometimes called C-curves or S-curves．

 To plot TTT curves，the particular steel is held at a given temperature and the structure is examined at predetermined intervals to record the amount of transformation taken place．It is known that the eutectoid steel (T80) under equilibrium conditions contains，all austenite above 723℃，whereas below，it is the pearlite．To form pearlite，the carbon atoms should diffuse to form cementite．The diffusion being a rate process，would require sufficient time for complete transformation of austenite to pearlite．From different samples，it is possible to note the amount of the transformation taking place at any temperature．These points are then plotted on a graph with time and temperature as the axes．Through these points，transformation curves can be plotted as shown in Fig.1 for eutectoid steel． Precision CNC machining parts The curve at extreme left represents the time required for the transformation of austenite to pearlite to start at any given temperature．Similarly，the curve at extreme right represents the time required for completing the transformation．Between the two curves are the points representing partial transformation. The horizontal lines Ms and Mf represent the start and finish of martensitic transformation.

  

Drilling and Milling Machines

Drilling and Milling Machines 

      Precision CNC machining parts Upright drilling machines or drill presses are available in a variety of sizes and types, and are equipped with a sufficient range of apindle speeds and automatic feeds to fit the neds of most industries. Speed ranges on a typical machine are from 76 to 2025 rpm., with drill feed from 0.002 to 0.020 in.per revolution of the spindle.   

  Radial drilling machines are used to drill workpieces that are too large or cumbersome to conveniently move. The spindle with the speed and feed changing mechanism is mounted on the radial arm; by combining the movement of the radial arm around column and the movement of the spindle assembly along the arm, it is possible to align the spindle and the drill to any position within reach of the machine. For work that is too large to conveniently support on the base, the spindle assembly can be swung out over the floor and the workpiece set on the beside the machine.    

 Plain radial drilling machines provide only for vertical movement of the spindle; universal machines allow the spindle to swivel about an axis normal to the radial arm and the radial arm to rotate about a horizontal axis, thus permitting drilling at any angle. 

 A multispindle drilling machine has one or more heads that drive the spindles through universal joints and telescoping splined shafts. All spindles are usually driven by the same motor and fed simultaneously to drill the desired number of holes. In most machines each spindle is held in an adjustable plate so that it can be moved relative to the others. The area covered by adjacent spindles overlap so that the machine can be set to drill holes at any location within its range. 

   Precision CNC machining parts The milling operation involves metal removal with a rotating cutter. It includes removal of metal from the surface of a workspiece, enlarging holes, and form cutting, such as threads and gear teeth. 

Within an knee and column type of milling machine the column is the main supporting member for the other components, and includes the base containing the drive motor, the spindle, and the cutters. The cutter is mounted on an arbor held in the spindle, and supported on its outer extremity by a bearing in the overarm. The knee is held on the column in dovetail slots, the saddle is fastened to the knee in dovetail slots, and the table is attached to the saddle. Thus, the build-up the knee and column machine provides three motions relative to the cutter. A four motion may be provided by swiveling the table around a vertical axis provided on the saddle. 

 Precision CNC machining partsFixed-bed milling machines are designed to provide more rigidity than the knee and column type. The table is mounted directly on the machine base, which provides the rigidity necessary for absorbing heavy cutting load, and allows only longitudinal motion to the table. Vertical motion is obtained by moving the entire cutting head.   

  Tracer milling is characterized by coordinated or synchronized movements of either the paths of the cutter and tracing elements, or the paths of the workpiece and model. In a typical tracer mill the tracing finger follow the shape of the master pattern, and the cutter heads duplicate the tracer motion.

Operational safety and environmental protection

Operational safety and environmental protection

 Precision wire cutting Along with advance in technology and human culture development, the people are more and more high to the working condition improvement and the environmental protection request. The electric spark forming processing as a result of its own characteristic, can have the driving fluid splash, the smog, the noise, the electromagnetic radiation, the noxious gas inevitably in the processing process and so on the safety factor and the pollution, is noticeable to the operator personal safety and the environment harm. Therefore, for the guarantee electrical finishing industry sustainable development, must act according to “the green manufacture principle”, the realization resources most effective use and the reject threshold produces with the emissions. Should take following measure specifically:

①         Precision wire cutting Seal engine bed work area. This is advantageous to the improvement driving fluid, the smog, the electromagnetic radiation and so on to the human body, the engine bed, the working conditions pollution, is advantageous in the operating process prevented receives an electric shock the danger as well as to the noxious gas centralized processing emissions;

 ②Precision wire cutting Vicarious technical utilization. For example, the environmental pollution which creates for the reduced use driving fluid, may in the guarantee processing efficiency, the processing precision, the processing cost as well as under the processing process stable premise, selects the pollution small driving fluid as far as possible, simultaneously should study, the development vigorously does not use the driving fluid the formed processing technology;

  ③ Reject post-processing. The waste liquid, the waste gas produces which after the processing in must pass through processing to be able to discharge. Needs to point out specially, has pollutant reasonable processing to the processing process, not only is advantageous to the enhancement work security, the reduction environmental pollution, but also is advantageous in improves operator's working conditions, causes when the operator work the mood is happy, this regarding enhances the electrical finishing industry the social image and the market competitive power also is extremely beneficial.

  

Electric spark forming processing craft trend of development

Electric spark forming processing craft trend of development

 Through processes the mechanism to the electric spark forming the research, further promulgates the electric discharge process the inherent laws, and take this as the instruction, impels the electric spark forming processing craft to the high efficiency, the high accuracy, the low loss direction to develop, meanwhile should pay attention to the micro refinement processing aspect the development. 

(1) processing process highly effective

 Precision wire cuttingNot only the processing process highly effective manifests in through the improvement electric spark machining servosystem, the control system, the driving fluid system, the engine bed structure and so on, reduces the above factor to the electric spark forming processing efficiency influence, enhances, the precision work efficiency thickly in under the guarantee processing precision premise, meanwhile should reduce the non-cutting time as far as possible (for example programming time, electrode and work piece localization time, maintenance time and so on), this needs to strengthen the engine bed the automatic programming function, expands the engine bed online backstage programming ability, the improvement and the development suitable electrode and the work piece positioning device.

 In the engine bed maintenance aspect, should strengthen the engine bed the multimedia functions and the online help function, regarding the common breakdown, the operator may act according to the computer prompt realization trouble shooting directly, simultaneously this is also advantageous in strengthens the engine bed the feasibility and operator's operation skill.

 (2) processing process precision 

Precision wire cutting Through uses a series of advanced processing technology and the technique, at present the electric spark forming processing precision had the comprehensive enhancement, some has been possible to achieve the mirror surface processing level. But looked from the overall that, the vanguard technology insufficiently is also mature in the actual production application and widespread, therefore has the necessity comprehensive impetus to have the vanguard technology further consummation and to develop to the industrial production direction. In the guarantee processing speed, under the processing cost premise, makes the electric spark forming processing the precision level further to enhance, causes the electric spark forming to process into some major parts, the essential components finally processing way. At the same time, to processes the precision the weight not to be able to limit merely to the work piece size precision and the surface roughness, but also should include the profile the GDOP, deterioration level thickness as well as the microscopic crack, the oxidation, the corrosion and so on. 

(3) processing process micro refinement

Precision wire cutting  An electric spark forming processing important application domain is the narrow trough, the deep cavity, the tiny components processing, therefore the processing process micro refinement will be the next important development direction. The electric spark processes the mechanism and the conventional electric spark forming processing tiny is same, but has own craft characteristic: Each pulse electric discharge energy is very small, driving fluid circulation difficulty, stable electric discharge gap scope small and so on. Based on these craft characteristic, the tiny electric spark forming processing processing equipment, the driving fluid circulatory system, the electrode preparation and so on inevitably and the conventional electric spark forming processing has the very big difference. Therefore, needs key to study the non-mechanical action

 and the disturbance to the processing process influence and so on, further enhances the processing efficiency, the processing precision and the processing process stability. 

(4) application scope expansion 

At present, not only the electric spark forming processing may process each kind of electric conduction metal material and the complex die space, but also can realize to the semiconducting material, the non-conducting material processing, and has obtained the good processing effect. At the same time, the electrode material type also unceasingly increases. This aspect main trend of development is: Further studies the semiconducting material, the non-conducting material electric spark machining mechanism, promotes its processing efficiency, the processing precision, the processing process stable enhancement, the expansion to be possible to process the material the scope; Besides the processing complex die space, further realizes to the three dimensional die space, the complex profile processing; Development performance superior new electrode material.

   

Electric spark forming processing theory trend of development

Electric spark forming processing theory trend of development

Precision wire cuttingIn recent years, the electric spark forming processing basic theory research not yet made the substantive progress, although some scholars to the processing process electric discharge trace, the material eclipse eliminated the principle and so on to propose some new views, but obtained the significant breakthrough by no means in the electric spark machining mechanism research aspect. The more active research area mainly concentrates in the processing craft theory and the control theory aspect.

  Precision wire cuttingIn the processing craft fundamental research aspect, how does the research hot spot mainly is enhance the electric spark forming processing the surface quality and the processing speed, reduces the loss, the development electric spark machining scope, as well as exploration complex, tiny structure processing method and so on. Will apply through the research results in the production practice, will comprehensively enhance the electric spark forming processing workability. In the control fundamental research aspect, the intelligent control always is the research key. The domestic and foreign production new electric spark forming processing engine bed mostly has used the intelligent control technology, this technical application makes the engine bed operation to be easier, requests to the operator lowly. At the same time, the intelligence control system has from the learning capability, but the online automatic monitor, the adjustment processing process, realizes the processing process optimized control.

 Although the electric spark forming processing fundamental research in aspects and so on basic theory, processing craft theory, control theory all has certain development and the enhancement, but the processing craft theory, the control theory need to obtain the further full scale development, must have the breakthrough in the entire electric discharge process mechanism research. Therefore, the electric spark forming processing fundamental research trend of development will be further is discussing the processing craft theory and the control theory, enhances the electric spark forming processing workability and the processing scope, obtains the better control effect at the same time, key research electric discharge process mechanism.

 The electric spark forming processing mechanism research has not made the unprecedented progress the primary cause except outside the electric discharge process itself complexity, randomness, but also because the research technique and the method lack the innovation. Therefore, it is necessary to profit from other research area the success experience, directs the human advanced research technique and the experimental technology, the victory tradition research technique limitation, the deep person analysis and the revelation entire electric discharge process intrinsic essence, the establishment may reflect objectively the electric discharge process rule the theoretical model, instructs the electric spark forming processing craft theory and the control theory research, but the computer simulation technical possibilities realizes this process effective tool

 electric spark forming processing equipment structure improvement

  Precision wire cutting The model modern machining engine bed development experience, the electric spark forming processing equipment develops to the numerical control direction is a irreversible tendency. On the one hand should by the high accuracy, the high velocity, change into the pursue goal automatically, seizes the market by the technical superiority; On the other hand should consider fully the equipment the performance price compared to, through to the engine bed function reasonable localization, makes the structure improvement and the modular design, uses the open numerical control system, enhances rationality which the engine bed designs, provides by the lowest price and the enough function to the user may satisfy each kind of electric spark forming processing engine bed which the different processing needs.

  Modern machining technological development impact, before suits uses the electric spark machining a part of processing domain to substitute gradually for the machining way. But, the modern science and technology development proposed to the components manufacture precision a higher request, each kind of high performance material application is day by day widespread, simultaneously, some components structure tends to the complication, the microminiaturization, thinly, this all causes the machining technology to be restricted in certain processing domain application, but these are exactly the electric spark forming processing technical superiority, also is it has the existing space and the development potential reality basis.

   

Electric spark forming processing technology present situation and trend of development

Electric spark forming processing technology present situation and trend of  development

 I、Introduction

Precision metal parts As an advanced technique of manufacture important branch, the special processing technology, the electric spark machining technology, since the 20th century 40's foundations, has had been through repeatedly in particular for more than half centuries the development, has become the advanced technique of manufacture domain indispensable important constituent. Enters after in particular the human for 1990s, along with high technology and new technology and so on information technology, networking, aviation and astronautics technology, materials science technology development, the electric spark forming processing technology also faces a deeper level, the high level direction is developing. Although some traditional processing technology through own unceasing renewal development as well as with other correlation technology fusion, difficult to process the material processing domain in some (especially in mold processing domain) to display the processing efficiency higher superiority, but these technical application has been impossible to substitute for the electric spark forming processing technology difficultly to process processing domain completely and so on in the material, complex profile, mold statuses. On the contrary, the electric spark forming processing technology through profits from other processing technology the development experience, to the micro refinement, highly effective directions and so on, precision, automation, intellectualization is developing unceasingly. 

II、Electric spark forming processing technology development present situation

 Precision metal parts At present, in electric spark machining basic theory research area, because the electric discharge process itself complexity, randomness as well as the research method lack the innovation, until now not yet made the unprecedented progress. But in processing craft and control fundamental research domain, because the research results may apply directly in the production practice, therefore has become in the present electric spark forming processing engineering research a more active domain, its research hot spot mainly concentrates in the highly effective processing technology, the high precise processing technology (glassy surface processing technology), the low loss processing technology, the tiny processing technology, the non-conducting material processing technology, the electric spark surface treatment technology, the intelligent control technology (for example artificial neural networks technology, fuzzy control technology, expert system and so on) as well as aspects and so on operational safety, environmental protection. In the process unit development aspect, the present new electric spark forming processing engine bed in aspects and so on processing function, processing precision, automaticity, reliability improved comprehensively, many engine beds have had online functions and so on examination, intelligent control, modulation, no longer is in the traditional significance special processing engine bed, but looks like in the machining the numerical control engine bed even to process the center.

 III、Electric spark forming processing technology trend of development

Precision metal parts The advanced technique of manufacture fast development and the manufacturing industry market competition aggravating proposed to the electric spark forming processing technology a higher request, simultaneously also for the electric spark forming processing technology processing theory research and the craft development, the equipment renewed has provided the new power. The next electric spark forming processing processing object will be supposed mainly to face the tradition machining not not easily to realize difficultly to process processings and so on material, complex profile, in which fine processing, the precise processing, the narrow dadoing, the deep cavity processing and so on becomes the development priorities. At the same time, but also should pay attention with other special processing technology or the traditionElectric spark forming processing technology present situation and trend of  development

 I、Introduction

Precision metal parts As an advanced technique of manufacture important branch, the special processing technology, the electric spark machining technology, since the 20th century 40's foundations, has had been through repeatedly in particular for more than half centuries the development, has become the advanced technique of manufacture domain indispensable important constituent. Enters after in particular the human for 1990s, along with high technology and new technology and so on information technology, networking, aviation and astronautics technology, materials science technology development, the electric spark forming processing technology also faces a deeper level, the high level direction is developing. Although some traditional processing technology through own unceasing renewal development as well as with other correlation technology fusion, difficult to process the material processing domain in some (especially in mold processing domain) to display the processing efficiency higher superiority, but these technical application has been impossible to substitute for the electric spark forming processing technology difficultly to process processing domain completely and so on in the material, complex profile, mold statuses. On the contrary, the electric spark forming processing technology through profits from other processing technology the development experience, to the micro refinement, highly effective directions and so on, precision, automation, intellectualization is developing unceasingly. 

II、Electric spark forming processing technology development present situation

 Precision metal parts At present, in electric spark machining basic theory research area, because the electric discharge process itself complexity, randomness as well as the research method lack the innovation, until now not yet made the unprecedented progress. But in processing craft and control fundamental research domain, because the research results may apply directly in the production practice, therefore has become in the present electric spark forming processing engineering research a more active domain, its research hot spot mainly concentrates in the highly effective processing technology, the high precise processing technology (glassy surface processing technology), the low loss processing technology, the tiny processing technology, the non-conducting material processing technology, the electric spark surface treatment technology, the intelligent control technology (for example artificial neural networks technology, fuzzy control technology, expert system and so on) as well as aspects and so on operational safety, environmental protection. In the process unit development aspect, the present new electric spark forming processing engine bed in aspects and so on processing function, processing precision, automaticity, reliability improved comprehensively, many engine beds have had online functions and so on examination, intelligent control, modulation, no longer is in the traditional significance special processing engine bed, but looks like in the machining the numerical control engine bed even to process the center.

 III、Electric spark forming processing technology trend of development

Precision metal parts The advanced technique of manufacture fast development and the manufacturing industry market competition aggravating proposed to the electric spark forming processing technology a higher request, simultaneously also for the electric spark forming processing technology processing theory research and the craft development, the equipment renewed has provided the new power. The next electric spark forming processing processing object will be supposed mainly to face the tradition machining not not easily to realize difficultly to process processings and so on material, complex profile, in which fine processing, the precise processing, the narrow dadoing, the deep cavity processing and so on becomes the development priorities. At the same time, but also should pay attention with other special processing technology or the tradition machining technology compound application, displays each processing method difficultly to process in the material processing fully the superiority, obtains the union increment effect. Is opposite says in the machining technology, the electric spark forming processing technology was still a young technology, therefore in the next development, will be supposed to profit from the experience and the achievement which in the machining technological development process will obtain, will process own technical characteristic according to the electric spark forming, will select the suitable processing theory, the control principle and the technique, and will have in the achievement foundation in oneself to consummate, the innovation unceasingly. The electric spark forming processing engine bed the tendency which develops to the numerical control direction already irreversible, but should pay attention cannot pursue blindly “large and complete”. should take the market as the guidance, the establishment has the open numerical control system. Overall, the electric spark forming processing technology next trend of development should be the high efficiency, the high accuracy, the low loss, the micro refinement, the automation, the security, the environmental protection and so on. machining technology compound application, displays each processing method difficultly to process in the material processing fully the superiority, obtains the union increment effect. Is opposite says in the machining technology, the electric spark forming processing technology was still a young technology, therefore in the next development, will be supposed to profit from the experience and the achievement which in the machining technological development process will obtain, will process own technical characteristic according to the electric spark forming, will select the suitable processing theory, the control principle and the technique, and will have in the achievement foundation in oneself to consummate, the innovation unceasingly. The electric spark forming processing engine bed the tendency which develops to the numerical control direction already irreversible, but should pay attention cannot pursue blindly “large and complete”. should take the market as the guidance, the establishment has the open numerical control system. Overall, the electric spark forming processing technology next trend of development should be the high efficiency, the high accuracy, the low loss, the micro refinement, the automation, the security, the environmental protection and so on.

Hydraulic System

Hydraulic System

  CNC machining parts The history of hydraulic power is a long one，dating from man’s prehistoric efforts to harness the energy in the world around him．The only sources readily available were the water and the wind—two free and moving streams.

  The watermill，the first hydraulic motor，was an early invention·  One is pictured on a mosaic at the Great Palace in Byzantium，dating from the early fifth century·The mill had been built by the Romans．  But the first record of a watermill goes back even further,  to around 100 BC，and the origins may indeed have been much earlier·The domestication of grain began some 5000 years before and some enterprising farmer is bound to have become tired of pounding or grinding the grain by hand．Perhaps，  in fact，the inventor was some

farmer’s wife，since she often drew the heavy jobs·

 CNC machining parts Manv mills staved in use until the end of the 19th century，but they had been in the  process of being replaced by the Steam engine as a source of power for the previous 150  years．The transmission of the power generated by the waterwheels was by shafting and  crude gears or pulleys．The steam engine for the first time employed an enclosed moving

 stream of fluid(steam) under pressure—the principle to be later employed in hydraulic  power transmission—for transmitting power continuously from the point of generation to  the place where it was used·

  The transmission of hydrostatic power to a distant point began long before that,however ．Hero of A1exandria，in the first century AD，built a device in which a fire on the temple  altar expanded air in a closed container．The air pressure forced water to travel along a tube

 to the temple doors where，spilling into a container，it provided the force through ropes and  pulleys to magically open the doors

  Hero also produced a steam engine of sorts．

 Its motion depended on the reaction forces   from jets of steam，as in the present steam turbine，but it was little understood and it was no   more than an interesting curiosity·

  The invention of early forms of the hydraulic pump has a similarly early origin·The first pumps were not used to develop hydraulic power，however' but only to transfer water for  irrigation or to remove it from mines

 Archimedes applied the principle of the screw to hydraulic machines in the third century BC． 

 His screw pumps were used to raise water for irrigation or to the level of aqueducts·The piston   pump，the first mechanical device capable of generating pressure in a column of liquid，is believed to have come from Egypt at a similarly early date．Like the screw pump，it was used only as a means for moving water and not as a means for generating hydraulic power·

  In more recent years， the role of leadership in hydraulic power application has been taken over largely by some of the larger earthmoving and construction equipment manufacturers the total Power involved is often greater than that required in even the largest aircraft systems．the concentration of this power in a few very large loads，as compared to the multitude of smaller loads in an airplane，has spurred the system designer to find new，creative ways to distribute and control the power．This he has succeeded in doing to obtain maximum precision of control and productivity while minimizing power consumption．

  in modern mobile and industrial applications，the system designer has made full use of the wonderful flexibiIity and adaptability of hydraulics．  It can readily be directed around corners and past involving joints that virtually defy mechanical power transmission．  It can be divided easily to serve individual loads or recombined to power a high，single一load demand． Electrical and pneumatic power distribution have similar flexibility，but lack the compactness

 and certain of the other important characteristics of hydraulics

   CNC machining parts A very significant feature of hydraulic power is its extreme power density． Fig．1 0．1 shows a comparison of a 400 hP(1hp=0·7457kW)hydraulic pumping source with a diesel engine and an electrical motor of the same power capacity．The contrast is obvious and is one that otters both an opportunity to the user of hydraulic power and a challenge to the designer

 of hydraulic components.

  The high—power density in a hydraulic pump or motor creates design challenges beyond those found in many other products·High loads on rapidly sliding surfaces，extreme fluid   velocities and rapidly recurring pressure applications on pumping elements(vanes，pistons。   gears) demand careful design attention to assure long life，complete reliability and efficient operation·The user,on the other hand，reaps the benefit of a family of apparatus that is highly responsive，finely controllable and simple to apply．When the designer understands the user’s needs and the user understands the equipment’s full capabilities，the maximum  potential of hydraulic power can be achieved．

Shaper, Planer, Milling and Grinding Machines

Shaper, Planer, Milling and Grinding Machines

 Shapers 

Precision metal parts Shapers are machine tools used primarily in the production of flat and angular surfaces. In addition, the shaper is used to machine irregular shapes and contours which are difficult to produce on other machine tools. Internal as well as external surfaces and shapes can be produced on the shaper. Common shapes produced on the shaper are flat, angular, grooves, dovetails, T-slots, keyways, slots, serrations, and contours. Single-point cutting tools similar to the type used on the lathe are used in machining most surfaces on the shaper. Contour surfaces can be produced with either a single-point tool or a formed cutting tool. When using a single-point cutting tool for contour surfaces, the depth of cut must be constantly regulated by the machine operator to achieve the proper contour . Profilingattachments can be used on some shapers to regulate the feed motion and provide duplication of other parts. Numerical control units also enable the production of irregular surfaces with constant regulation of the depth of cut.

   Shapers are classified by the plane in which the cutting action occurs, either horizontal or vertical. In addition the horizontal-type shapers are further classified as push or pull cut. A push-cut shaper cuts while the ram is pushing the tool across the work, and a pull cut machine removes material while the tool is pulled toward the machine. Vertical shapers use a pushing-type cutting action and are sometimes referred to as slotters or keyseaters.

 Planers 

Precision metal parts Planers are similar to shapers because both machines are primarily used to produce flat and angular surfaces. However, planers are capable of accommodating much larger work- pieces than the shaper. In planer operations the workpiece is mounted on the table which reciprocates in a horizontal plane providing a straight-line cutting and feed action. Single-point cutting tools are mounted on an overhead cross rail and along the vertically supported columns. The cutting tools are fed into or away from the workpiece on either the horizontal or vertical plane, thus being capable of four straight-line feed motions.  Cutting speeds are slow on the planer because of the workpiece size and type of cutting tool being used. In order to increase the production of the planer, multiple tooling stations are employed. Two tooling stations are located on the overhead cross rails, with usually one tooling station on the vertical supports. Another method of increasing production on the planer is to mount a number of workpieces on the table at the same time. This method is only feasible when the workpieces require the same cut and are relatively small in size. The planer size is designated by the maximum workpiece capacity of the machine. The height, width, and length of the workpiece that can be accommodated on the planer's worktable varies with the type of planer.

 Milling Machines

  Precision metal parts Milling machines are probably the most versatile machine tools used in modern manufacturing with the exception of the lathe. Primarily designed to produce flat and angular surfaces, the milling machine is also used to machine irregular shapes, surfaces, grooves, and slots. The milling machine can also be used for drilling, boring, reaming, and gear-cutting operations.   A number of different types of milling machines are manufactured in order to serve the multitude of needs and the diverse applications. Milling machines are classified according to their structure and include column-knee, fixed bed, planer, and special machines.

 Grinding Machines

  Grinding machines utilize abrasive grains, bonded into various shapes and sizes of wheels and belts to be used as the cutting agent. Grinding operations are used to impart a high-quality surface finish on the workpiece. In addition, the dimensional accuracy of the workpiece is improved since tolerances of 0.00001 in. [0. 00025mm] are possible in grinding operations. Both internal and external surfaces can be ground by using the variety of grinding machines available. Related operations—which use abrasivesin various forms such as paste, powder, and grains—include lapping, honing, and drum finishing.   

  Grinding machines are classified according to the type of surface produced. Common surfaces and classifications of grinding machines are surface, cylindrical, and special machines.

Design of machine elements of 2

Design of machine elements of 2

 Precisionparts Machine design is a vast field of engineering technology. As such, it begins with the conception of an idea and follows through the various phases of design analysis, manufacturing, marketing and consumerism. The following is a list of the major areas of consideration in the general field of machine design:

  ① Initial design conception;  ② Strength analysis; ③ Materials selection;   ④ Appearance; ⑤ Manufacturing;  ⑥ Safety;  ⑦ Environment effects;  ⑧Reliability and life;                               
   Strength is a measure of the ability to resist, without fails, forces which cause stresses and strains. The forces may be;

 ① Gradually applied;  ② Suddenly applied;  ③ Applied under impact;   ④ Applied with continuous direction reversals;  ⑤ Applied at low or elevated temperatures.       

 Precisionparts If a critical part of a machine fails, the whole machine must be shut down until a repair is made. Thus, when designing a new machine, it is extremely important that critical parts be made strong enough to prevent failure. The designer should determine as precisely as possible the nature, magnitude, direction and point of application of all forces. Machine design is mot, however, an exact science and it is, therefore, rarely possible to determine exactly all the applied forces. In addition, different samples of a specified material will exhibit somewhat different abilities to resist loads, temperatures and other environment conditions. In spite of this, design calculations based on appropriate assumptions are invaluable in the proper design of machine.

  Precisionparts Moreover, it is absolutely essential that a design engineer knows how and why parts fail so that reliable machines which require minimum maintenance can be designed. Sometimes, a failure can be serious, such as when a tire blows out on an automobile traveling at high speeds. On the other hand, a failure may be no more than a nuisance. An example is the loosening of the radiator hose in the automobile cooling system. The consequence of this latter failure is usually the loss of some radiator coolant, a condition which is readily detected and corrected.

 The type of load a part absorbs is just as significant as the magnitude. Generally speaking, dynamic loads with direction reversals cause greater difficulties than static loads and, therefore, fatigue strength must be considered. Another concern is whether the material is ductile or brittle. For example, brittle materials are considered to be unacceptable where fatigue is involved.     
  In general, the design engineer must consider all possible modes of failure, which include the following:

①Stress; ② Deformation;    ③ Wear;  ④ Corrosion;  ⑤ Vibration;    ⑥ Environmental damage;     ⑦ Loosening of fastening devices.                           

   The part sizes and shapes selected must also take into account many dimensional factors which produce external load effects such as geometric discontinuities, residual stresses due to forming of desired contours, and the application of interference fit joints.

  

Design of machine elements

Design of machine elements

    Precision metal parts  The principles of design are, of course, universal. The same theory or equations may be applied to a very small part, as in an instrument, or, to a larger but similar part used in a piece of heavy equipment. In no ease, however, should mathematical calculations be looked upon as absolute and final. They are all subject to the accuracy of the various assumptions, which must necessarily be made in engineering work. Sometimes only a portion of the total number of parts in a machine are designed on the basis of analytic calculations. The form and size of the remaining parts are designed on the basis of analytic calculations. On the other hand, if the machine is very expensive, or if weight is a factor, as in airplanes, design computations may then be made for almost all the parts.

    Precision metal parts   The purpose of the design calculations is, of course, to attempt to predict the stress or deformation in the part in order that it may sagely carry the loads, which will be imposed on it, and that it may last for the expected life of the machine. All calculations are, of course, dependent on the physical properties of the construction materials as determined by laboratory tests. A rational method of design attempts to take the results of relatively simple and fundamental tests such as tension, compression, torsion, and fatigue and apply them to all the complicated and involved situations encountered in present-day machinery

   Precision metal parts  In addition, it has been amply proved that such details as surface condition, fillets, notches, manufacturing tolerances, and heat treatment have a market effect on the strength and useful life of a machine part. The design and drafting departments must specify completely all such particulars, must specify completely all such particulars, and thus exercise the necessary close control over the finished product.

  

Machinability

Machinability

 Cnc milling  Machinability means several things. To production men it generally means being able to remove metal at the fastest rate, leave the best possible finish, and obtain the longest possible tool life. Machinability applies to the tool-work combination.

 Cnc milling It is not determined by hardness alone, but by the toughness, microstructure, chemical composition, and tendency of a metal to harden under cold work. In the misleading expression “too hard to machine”, the word “hard” is usually meant to be synonymous with “difficult”. Many times a material is actually too soft to machine readily. Softness and toughness may cause the metal to tear and flow ahead of the cutting tool rather than cut cleanly. Metal that are inherently soft and tough are sometimes alloyed to improve their machinability at some sacrifice in ductility. Examples are use of lead in brass and of sulfur in steel.  。  

 Machinability is a term used to indicate the relative ease with which a material can be machined by sharp cutting tools in operations such as turning, drilling, milling, broaching, and reaming

 Cnc milling  In the machining of metal, the metal being cut, the cutting tool, the coolant, the process and type of machine tool, and the cutting conditions all influence the results. By changing any one of these factors, different results will be obtained. The criterion upon which the ratings listed are based is the relative volume of various materials that may be removed by turning under fixed conditions to produce an arbitrary fixed amount of tool wear.

Internal stresses

Internal stresses

Precision CNC machining parts Cold forming is done above the yield point in the work-hardening range, so internal stresses can be built up easily. Evidence of this is the springback as the work leaves the forming operation and the warpage in any subsequent heat treatment. Even a simple washer might, by virtue of the internal stresses resulting from punching and then flattening, warp severely during heat treating.  believed in the virtue of prayer.

 Precision CNC machining parts  When doubt exists as to whether internal stresses will cause warpage, a piece can be checked by heating it to about 1100 and then letting it cool. If there are internal stresses, the piece is likely to deform. Pieces that will warp severely while being heated have been seen, yet the heat-treater was expected to put them through and bring them out better than they were in the first place

 Welding

 The maximum carbon content of plain carbon steel safe for welding without preheating or subsequent heat treatment is 0.3%. higher-carbon steel is welded every day, but only with proper preheating. There are two important factors: the amount of heats that is put in  the rate at which it is removed

 Precision CNC machining parts  Welding at a slower rate puts in more heat and heats a large volume of metal, so the cooling rate due to loss of heat to the base metal is decreased. A preheat will do the same thing. For example, sae4150 steel, preheated to 600 or 800, can be welded readily. When the flame or arc is taken away from the weld, the cooling rate is not so great, owing to the higher temperature of the surrounding metal and slower cooling results. Even the most rapid air-hardening steels are weldable if preheated and welded at a slow rate.

Selection of Construction Materials

Selection of Construction Materials

Precision parts There is not a great difference between “this” steel and “that” steel; all are very similar in mechanical properties. Selection must be made on factors such as hardenability, price, and availability, and not with the idea that “this” steel can do something no other can do because it contains 2 percent instead of 1 percent of a certain alloying element, or because it has a mysterious name. A tremendous range of  properties is available in any steel after heat treatment; this is particularly true of alloy steels.

 Considerations in fabrication

 Precision partsThe properties of the final part (hardness, strength, and machinability), rather than properties required by forging, govern the selection of material. The properties required for forging have very little relation to the final properties of the material; therefore, not much can be done to improve its forgeability. Higher-carbon steel is difficult to forge. Large grain size is best if subsequent heat treatment will refine the grain size.

 Low-carbon, nickel-chromium steels are just about as plastic at high temperature under a single 520-ft·lb(1 ft·lb=1.35582J) blow as plain steels of similar carbon content. Nickel decreases forgeability of medium-carbon steels, but has little effect on low-carbon steels. Chromium seems to harden steel at forging temperatures, but vanadium has no discernible effect; neither has the method of manufacture any effect on high-carbon steel.

 Formability

 Precision parts  The cold-formability of steel is a function of its tensile strength combined with ductility. The tensile strength and yield point must not be high or too much work will be required in bending; likewise, the steel must have sufficient ductility to flow to the required shape without cracking. The force required depends on the yield point, because deformation starts in the plastic range above the yield point of steel. Work-hardening also occurs here, progressively stiffening the metal and causing difficulty, particularly in the low-carbon steels.

 It is quite interesting in this connection to discover that deep draws can sometimes be made in one rapid operation that could not possibly be done leisurely（in two or three. If a draw is half made and then stopped, it may be necessary to anneal before proceeding, that is, if the piece is given time to work-harden. This may not be a scientific statement, but it is actually what seems to happen.