2016年10月31日星期一

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 definitionLikewisethe 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 wherein a single diagram all the three parameters are plottedBecause of the shape of the curvesthey are also sometimes called C-curves or S-curves

 To plot TTT curvesthe particular steel is held at a given temperature and the structure is examined at predetermined intervals to record the amount of transformation taken placeIt is known that the eutectoid steel (T80) under equilibrium conditions containsall austenite above 723℃,whereas belowit is the pearliteTo form pearlitethe carbon atoms should diffuse to form cementiteThe diffusion being a rate processwould require sufficient time for complete transformation of austenite to pearliteFrom different samplesit is possible to note the amount of the transformation taking place at any temperatureThese points are then plotted on a graph with time and temperature as the axesThrough these pointstransformation 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 temperatureSimilarlythe curve at extreme right represents the time required for completing the transformationBetween the two curves are the points representing partial transformation. The horizontal lines Ms and Mf represent the start and finish of martensitic transformation.
  
  Precision CNC machining parts

2016年10月23日星期日

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.

 Precision CNC machining parts

2016年10月16日星期日

Introduction of Machining

Introduction of Machining
  Precision CNC machining parts Machining as a shape-producing method is the most universally used and the most important of all manufacturing processes. Machining is a shape-producing process in which a power-driven device causes material to be removed in chip form. Most machining is done with equipment that supports both the work piece and cutting tool although in some cases portable equipment is used with unsupported workpiece. 
 Precision CNC machining parts  Low setup cost for small quantities. Machining has tow applications in manufacturing. For casting, forging, and pressworking, each specific shape to be p5roduced, even one part, nearly always has a high tooling cost. The shapes that may be produced, even one part, nearly always has a high tooling cost. The shapes that may be produced by welding depend to a large degree on the shapes of raw material that are available. By making use of generally high cost equipment but without special tooling, it is possible, bu machining, to start with nearly any form of any material, so long as the exterior dimensions are great enough, and produce any desired shape from any material. Therefore, machining is usually the preferred method for producing one or a few parts, even when the design of the part would logically lead to casting, forging or pressworking if a high quantity were to be produced.  Close accuracies, good finishes. The second application for machining is based on the high accuracies and surface finishes possible.

 Precision CNC machining parts  Many of the parts machined in low quantities would be produced with lower but acceptable tolerances if produced in high quantities by some other process. On the other hand, many pars are given shapes by some high quantity deformation process and machined only on selected surfaces where high accuracies are needed. Internal threads, for example, are seldom produced by any means other than machining and small holes in pressworked parts may be machined following the pressworking operations.
  
 Precision CNC machining parts

2016年10月9日星期日

Grinding automation and intellectualization

Grinding automation and intellectualization 
 Precision’s grinding With mechanical manufacturing in FMS (flexible manufacturing system) and CIMS (computer integrated manufacturing system), IMS (intelligent manufacturing system) height automation development direction, the grinding automation requirements are put forward. The development of the CNC grinding machine with CNC lathe, milling machine and so on started late. In the 1980 s and 90 s is a CNC grinding machine for rapid development and entered the popularizing period of practical. In recent years, almost all kinds of grinder CNC products, CNC tool grinding machine from 3 to 10 shaft axis development. Which can realize online measurement, automatic switching of grinding wheel and the emergence of the automatic unloading workpieces milling machining center, mark CNC grinding reached a new level. Grinding CNC system development also have great progress, many special grinding CNC software and systems have been commercialized. In the 1990 s, Japan announced about intelligent grinding results. Use of monitoring information and database, adaptive optimization in grinding condition and the judgment condition of grinding, using computer simulation and virtual technology, establish a realistic virtual grinding environment, to implement the intelligent of the grinding. Continuous track the use of grinding technology, making the grinding technology has made great development. 

 Grinding process monitoring and detection technology   
  Precision’s grinding  Implementation of intelligent computer control of grinding, grinding process is an important problem in the control room. Solve the grinding process, such as the phenomenon of signal identification, signal sampling, signal processing, feedback and compensation, need high sensitive sensor, also need to have expert system or intelligent system and the software design and other technical support.For grinding wheel wear and tear of using acoustic emission monitoring system. Because of the complexity of the grinding process, the grinding process of the monitoring system in theory and practical aspect still has many problems unsolved. Parts after the grinding size, shape and position accuracy, surface quality of the test is divided into offline and online detection.For super precision grinding and free abrasive machining high precision and low surface roughness obtained after detection, high-precision grinding on the surface of the on-line automatic detection are much harder than cars, milling, high sensitivity is the key to development of sensor technology and signal acquisition, recognition and processing technologies.
  Software of grinding technology

  Precision’s grinding  High performance CNC grinding machine should be equipped with a complete software system. Of intelligence information processing and data input of grinding, grinding mode selection and grinding the arrangement of the order, condition of grinding, grinding wheel dressing and grinding automatically selected, the state of the grinding process simulation and virtual detection and compensation, are in software design and development of a reasonable solution.All countries in the development of expert system and intelligent system software. Expert system is a branch of artificial intelligence research, and its essence is a kind of application system. Problem solving ability with expert level in the field of grinding process system, can effectively solve complex problems in the field of grinding.

Precision’s grinding part