China Shenzhen Perfect Precision Product Co., Ltd. company news

The general principles of precision parts processing, that is, the general principles of precision parts processing process route, mainly from the following four points to elaborate. 1, the benchmark first That is, first processing the reference surface, parts in the machining process, as the appearance of the positioning reference should be processed first, in order to provide a fine reference for the subsequent processes as soon as possible. 2, divide the processing stage Mechanical processing quality requirements of the appearance, are divided into processing stages, generally can be divided into roughing, semi-finishing and finishing three stages. Mainly to ensure the quality of processing; conducive to the scientific application of equipment; to facilitate the arrangement of heat treatment processes; and to facilitate the discovery of defects in the blank. 3、First surface and then hole For the box, bracket and connecting rod and other parts should be machined plane first and then hole. This can be positioned with the plane to process the hole, to ensure the accuracy of the position of the plane and hole, and to bring convenience to the processing of the hole on the plane. 4、Light finishing processing The main appearance of the finishing process, such as grinding, honing, fine grinding, rolling processing, etc., should be placed at the end of the process route stage. The development of precision parts machining process route general principles, precision parts machining process procedures, can be broadly divided into two links. First of all, the process route of parts processing, and then determine the process size of each process, the equipment and process equipment used, as well as cutting specifications, work quotas.

In the machining industry, processing accuracy often largely determines the quality of machined parts, and CNC precision parts machining itself is a very demanding means of processing, its relative to traditional processing methods to achieve better results, there are many other processing methods do not have the advantages, so what are the advantages of CNC precision parts machining? 1、Multi-axis control linkage: Usually three axis linkage is used the most, but through some adjustments can do four-axis, five-axis, seven-axis or even more linked axis machining center.   2, machine parallel: common machining center whose function is also relatively fixed, you can put the machining center and turning center, or vertical, horizontal machining center combined together, which can increase the machining center processing range and processing capacity.   3, tool breakage warning: the use of some technical detection means, you can timely find the tool wear, damage to the situation, and alarm, so that you can do timely replacement of tools to ensure the quality of parts processing. 4, tool life management: can be multiple tools working at the same time and multiple blades on the same tool for unified management to improve production efficiency.   5, machine tool overload power-off protection: according to the production process load set the maximum load level, when the load reaches the set value, the machine tool can achieve automatic power-off shutdown, in order to implement the protective effect on the machine tool.

Precision electronic original parts are produced by intelligent machine tools through computer control in a vacuum machine, what about precision parts machining, how are precision parts produced?   First of all, what is precision parts processing, it is actually a kind of mechanical processing, but more precise, the production of machinery and process requirements are relatively high. With the development of industrialization, precision machining classification more and more, the direction is more and more fine, more and more specialized. So the future of precision machinery more and more integrated, it is not the original simple mechanical processing, it is combined with high-tech precisely better play its role, especially the processing of digitalization so that its development has produced a qualitative leap. In the future, it will become an important science, serving the development of industry.   Any piece of machinery and equipment is composed of many different small parts, each part plays a vital role. Parts need to be assembled, so precision mechanical parts processing manufacturers will be for such needs for reprocessing, a variety of different parts after processing we can get more suitable for their parts, so in order to make these products better for their own service, so many people are less precision machining this important link. In order to ensure precision parts processing accuracy, coarse and fine mechanical parts processing is best to be carried out separately. Because rough mechanical parts processing, cutting volume, the workpiece by the cutting force, clamping force, more heat, as well as mechanical parts processing surface has a more significant machining hardening phenomenon, the workpiece exists inside a large internal stress, if rough, rough mechanical parts processing continuously, the precision of the parts after finishing will be quickly lost because of the redistribution of stress. In the precision parts processing process route, often arranged with heat treatment process. Heat treatment process location is arranged as follows: in order to improve the cutting performance of the metal, such as annealing, normalizing, tempering, etc., generally arranged in mechanical parts before processing.   The processing process of precision parts is very strict, into the tool, out of the tool ring interlocking. Hold the size of the precision accuracy, can reduce the loss of material to reduce costs. For example, 1mm plus or minus how many microns, etc., if the size of the wrong will become scrap, the parts can not be used.

In the precision mechanical parts processing before, must pay attention to the density of the material, if the density is too large, equivalent to the hardness is also very large, and the hardness if more than the hardness of the lathe turning tool, it is impossible to process, not only will damage the parts, but also cause danger, such as turning tool flying out of the crash injury. So, what are the requirements of precision mechanical parts processing on the material? What are the requirements of precision mechanical parts processing material For precision machining materials are divided into two categories, metal materials and non-metallic materials. For metal materials, the hardness of stainless steel is the largest, followed by cast iron, followed by copper, and finally aluminum. The processing of ceramics, plastics and other non-metallic materials belong to the processing. Stainless steel materials used for precision machining of mechanical parts   1. First of all, the requirements of the material hardness, for some occasions, the higher the hardness of the material is the better, just limited to the hardness requirements of the processing machine parts, processing materials can not be too hard, if harder than the machine parts can not be processed. 2. Secondly, the material soft and hard moderate, at least one grade lower than the hardness of the machine, but also depends on the role of the processed device is to do what with the machine parts reasonable selection of materials. In short, precision machining of the material requirements or some, not what material is suitable for processing, such as too soft or too hard material, the former is not necessary for processing, and the latter is not processed. Therefore, in general, for mechanical processing, the material material should be lower than the hardness of the machine tool, so that it can be processed. Not what materials can be precision machining, some materials are too hard, more than the hardness of the processing machine parts, it is possible to crash the machine parts, so these materials are not suitable for precision machining, unless the machine parts made of special materials, or laser cutting.

Engaged in machining, high-precision mechanical parts manufacturing, the selection of blanks to determine, not only affect the economy of the manufacture of blanks, but also affect the economics of machining. Therefore, in determining the blank, both the hot processing aspects should be considered, as well as economic aspects, but also to take into account the requirements of cold processing, in order to determine the blank from this link, to reduce the manufacturing cost of parts. First. Castings   The shape of complex parts blank, it is appropriate to use casting methods of manufacture. Most of the current castings with sand casting, which is divided into wooden mold manual modeling and metal mold machine modeling. Wooden mold hand-shaped castings with low accuracy, processing surface allowance, low productivity, suitable for single-piece small batch production or large parts of the casting. Metal mold machine molding high productivity, casting accuracy, but the high cost of equipment, the weight of the casting is also limited, suitable for mass production of small and medium-sized castings. Second, a small number of small castings with high quality requirements can be used for special casting, such as pressure casting, centrifugal manufacturing and investment casting.   Second, forgings   Mechanical strength requirements of high steel parts, generally to use forging blanks. Forgings are free forging forgings and die forgings of two kinds. Free forging forgings can be manually forged (small blanks), mechanical hammer forging (medium-sized blanks) or press press forging (large blanks) and other methods to obtain. The accuracy of such forgings is low, the productivity is not high, the machining allowance is large, and the structure of the parts must be simple, suitable for single and small batch production, as well as the manufacture of large forgings.   The accuracy and surface quality of the forgings are better than the free forgings, and the shape of the forgings can also be more complex, and thus can reduce the machining allowance. The production efficiency of die forging is much higher than that of free forging, but it needs special equipment and forging die, so it is suitable for small and medium-sized forgings with large batches. Three, profiles   Profiles can be divided into: round steel, square steel, hexagonal steel, flat steel, angle steel, channel steel, I-beam and other special cross-sectional profiles according to the shape of the section. Profiles have two types of hot-rolled and cold-drawn. Hot-rolled profiles have low accuracy, but are inexpensive and used for general parts of the blank; cold-drawn profiles are smaller in size, high in accuracy, easy to achieve automatic feeding, but higher in price, and are used for larger batch production, suitable for automatic machine tool processing.   Fourth, the welded parts   Welded parts are obtained by welding method, the advantages of welding is simple manufacturing, short cycle time, saving materials, the disadvantage is poor vibration resistance, deformation, need to be processed by aging before mechanical processing.

Numerical control machining process is derived from conventional machining process, and it is an organic combination of conventional machining process, computer numerical control technology, computer aided design and auxiliary manufacturing technology. Due to the continuous development of technology, more and more parts need precision machining in modern manufacturing industry, and the requirements for machining accuracy and workpiece surface complexity are also getting higher and higher. Therefore, CNC machining has been widely concerned, but in terms of cost saving, CNC machining is still more expensive than traditional machining. Now let's introduce the difference between CNC machining and traditional machining. 1. Processing technology In the ordinary machining process, both the positioning datum, clamping method, tools, cutting methods and other aspects can be simplified, but the data processing process is more complex, and these factors need to be fully considered. Moreover, even if the same processing task, the CNC processing process can have multiple schemes, which can arrange multiple processing parts and processing tools as the main line, The process is characterized by diversification, which is the difference between CNC processing and traditional machining process. 2. Clamping and fixture In CNC machining process, not only the coordinate direction of fixture and machine tool should be relatively fixed, but also the dimensional relationship between parts and machine tool coordinate system should be coordinated. In addition, the two steps of positioning and clamping need to be effectively controlled during the clamping process. Moreover, under the traditional machining process, due to the limited processing capacity of the machine itself, it is necessary to carry out multiple clamping during the processing. And the need to use special fixtures, which leads to higher costs in the design and manufacturing of fixtures, virtually increasing the production cost of products. However, CNC machining process positioning can be debugged with instruments, and in most cases, special fixture design is not required, so its cost is relatively low. 3. Tools In the process of machining, the tool selection needs to be determined according to the different machining processes and methods. Especially in CNC machining, the use of high-speed cutting is not only conducive to the improvement of machining efficiency, but also can guarantee the machining quality, effectively reduce the probability of cutting deformation, and shorten the machining cycle. Therefore, the demand for cutting tools is further increased under the instruction of cutting. At present, there is also a dry cutting method, which can cut without cutting fluid or only with a small amount of cutting fluid, so the tool needs to have good heat resistance. Compared with ordinary machining process, CNC machining process has higher requirements on the performance of tools.

What is a cylindrical milling cutter? Milling cutter is a rotary cutter with one or more cutter teeth for milling. The cylindrical milling cutter is commonly used to process plane and 45 degree chamfer milling cutter on horizontal milling machine. The cutter teeth are distributed on the circumference of the milling cutter. The cylindrical milling cutter is divided into straight teeth and spiral teeth according to the tooth shape, and coarse teeth and fine teeth according to the number of teeth. The helical coarse tooth milling cutter has few teeth, high tooth strength and large chip holding space, which is suitable for rough machining, while the fine tooth milling cutter is suitable for fine machining. Multiple milling cutters can be combined for wide plane milling, and the combination must be left and right staggered helical teeth. The cylindrical milling cutter has high productivity because the milling cutter rotates continuously during milling and allows higher milling speed. In continuous milling, each cutter tooth is in continuous cutting, especially in end milling. The milling force fluctuates greatly, so vibration is inevitable. When the vibration frequency is the same as or multiples of the natural frequency of the machine tool, the vibration is most serious. In addition, when high-speed milling, the cutter teeth are subject to periodic thermal and cold shocks, which are prone to cracks and blade breakage, reducing the tool durability. The multi cutter and multi edge cutting milling cutter has many cutter teeth, and the total length of the cutting edge is large, which is conducive to improving the tool durability and productivity. It has many advantages. But there are also the following two problems: First, the cutter teeth are prone to radial runout, which will lead to unequal load of cutter teeth, uneven wear, and affect the quality of machined surfaces; Second, the chip space of the cutter teeth must be sufficient, otherwise the cutter teeth will be damaged. Different milling methods According to different processing conditions, in order to improve the tool durability and productivity, different milling methods can be selected, such as up milling, down milling, symmetric milling, asymmetric milling, etc. In addition to cylindrical milling cutter, end milling cutter is also commonly used. So, what is the difference between cylindrical milling cutter and end milling cutter? The most direct difference is that the cylindrical milling cutter should be threaded on the cutter bar for use, and the end milling cutter can be directly inserted into the taper hole of the spindle for use. The end mill is used to process grooves and step surfaces. The cutter teeth are on the circumference and end face, and generally cannot feed along the axial direction. When the end milling cutter has a through center end tooth, it can be fed axially. Moreover, the application scope and requirements of high-speed steel end milling cutter are relatively broad, and even if the cutting conditions are slightly inappropriate, there will not be too big a problem. Although carbide end milling cutter has good wear resistance in high-speed cutting, its application range is not as wide as that of high-speed steel end milling cutter, and the cutting conditions must strictly meet the requirements of the tool.

In machining, cutting tools are the basic technological equipment for cutting. They are in direct contact with the parts to be machined. Different tools can process different parts' structures and surfaces, which play a vital role in machining. They can be called "industrial teeth". As consumables, the tool itself has a certain life span. Different materials and specifications of tools have different life spans; For mass production, tool consumption also accounts for an important part of the processing cost. Therefore, it is a common problem for the manufacturing industry to improve tool life, control tool consumption, reduce processing costs and improve production efficiency. Existing technology Tool dressing is a way to improve tool life. However, the traditional manual equipment (such as manual grinder Fig. 1) can not meet the user's requirements in terms of precision, efficiency, reliability and safety. At the same time, enterprises also need to train professional tool grinding personnel, which increases part of the human cost. technological development Aiming at the above problems and combining the existing resources of the enterprise, we have developed a set of technical solutions that use CNC machining centers to achieve tool grinding automation: First of all, because the tool materials are generally hard, only grinding can be used to change its shape. Grinding wheel abrasive grains of different materials are suitable for grinding tools of different materials, and the size of abrasive grains required for different parts of the tool is also different, to ensure the best combination of edge protection and machining efficiency. Therefore, the first problem to be solved by using CNC machining center for tool dressing is the type and clamping mode of grinding wheel; Considering the low price of alumina grinding wheel, and easy to repair into different shapes for grinding complex tools, however, the tools that can be grinded are too simple (can be used to repair HSS (high speed steel) tools), and it is difficult to clamp and replace them frequently, so diamond grinding wheels that can repair more tools (HSS (high speed steel), PM-HSS (metallurgical powder high speed steel) and HM (cemented carbide steel) tools) are used. Lock the diamond grinding wheel onto the handle of the milling cutter with a special nut, so that the diamond grinding wheel can be clamped onto the cutter head of the CNC machining center and the spindle of the machine table In addition, it is necessary to consider the clamping and positioning method of the grinding tool: use the telescopic cylinder to cooperate with the self-made elastic rigid jacket to clamp the tool, and fix the tool clamp on the four axis platform (as shown in Figure 2), so as to ensure the parallelism and straightness of the four axes erected, which can ensure the parallelism and straightness of the grinding tool, and at the same time, enable the grinding tool to move in the X axis, Y axis and a axis directions. With the movement of the machine table spindle in the Z axis direction, the tool edge can be grinded at different angles. Moreover, the most critical technology of using CNC machining center to repair mold tools lies in the use of probes. Using high-precision probes with the detection program input by the machining center can confirm the tool grinding zero point, the tool grinding position, and the number of tool edges, and feed back the measurement results of these variables to the CNC machining center's numerical control system to input the tool grinding program prepared in advance for tool grinding. Of course, in order to realize the automation of tool grinding, we also need to add an automated assembly line (Figure 6): through self design, we can get the material tray for placing the tool (Figure 4), so that the manipulator can accurately position the tool, thus realizing the loading and unloading of the tool. With the CNC processing center, as well as the assembly line device and the final high-precision detection device (Figure 5), we can achieve the complete automation of tool grinding. The specific machining process of CNC machining center tool grinding can take the grinding of end milling cutter as an example: for the worn end milling cutter, the worn blade must be cut off and reground to obtain the required blade. Of course, this needs to ensure the effective blade length of the cutter. If it cannot be guaranteed, the end milling cutter cannot be reground. For CNC machining centers, we can preset the maximum cutting length and the cutting amount each time. Each time the probe is cut out, it will be detected once, and the cutting amount will be accumulated once; If it is detected that the blade part is still missing, it shall be cut again, and other parts of the tool can be further grinded until the blade is complete; If the cutting amount exceeds the maximum cutting length, the tool cannot be reground. The next step is to grind the chip breaking groove, then grind out the back angle of the tool, and finally grind out the bottom edge of the tool. These can be achieved by using the matching movement between X axis, Y axis, Z axis and a axis through program design in advance.

◆ Common sense of sand blasting and rust removal Sand blasting derusting uses compressed air as the power to form a high-speed jet beam to spray the materials (copper ore, quartz sand, carborundum, iron sand, Hainan sand) to the surface of the workpiece to be treated at a high speed, so that the appearance or shape of the external surface of the workpiece surface changes. Due to the impact and cutting effect of the abrasive on the workpiece surface, the workpiece surface can obtain a certain degree of cleanliness and different roughness, The mechanical properties of the workpiece surface are improved, so the fatigue resistance of the workpiece is improved, the adhesion between the workpiece and the coating is increased, the durability of the coating is extended, and it is also conducive to the leveling and decoration of the coating. ◆ Application scope of sand blasting 1. Sand blasting before workpiece coating and workpiece bonding can remove all dirt such as rust skin on the surface of the workpiece, and establish a very important basic diagram (commonly called rough surface) on the surface of the workpiece. Moreover, it can achieve different degrees of roughness by changing abrasives of different particle sizes, such as the abrasives of flying abrasive abrasives, which greatly improves the binding force between the workpiece and coatings and plating materials. Or the bonding parts can be bonded more firmly with better quality. 2. The cleaning, polishing and sandblasting of the rough surface of castings and workpieces after heat treatment can clean all dirt (such as oxide skin, oil stain and other residues) on the surface of castings and forgings and workpieces after heat treatment, and polish the surface of workpieces to improve the smoothness of workpieces, which can expose uniform metal color of workpieces, making the appearance of workpieces more beautiful and good-looking. 3. Burr cleaning and surface beautification sandblasting of machined parts can clean the tiny burrs on the surface of the workpiece, make the surface of the workpiece more smooth, eliminate the harm of burrs, and improve the grade of the workpiece. And sandblasting can make a small round corner at the junction of the workpiece surface, making the workpiece more beautiful and precise. 4. Improve the mechanical properties of parts After sandblasting, the mechanical parts can produce even and fine concave convex surfaces on the surface of the parts, so that the lubricating oil can be stored, thus improving the lubricating conditions, reducing noise and increasing the service life of the machinery. 5. Polishing function For some special purpose workpieces, sandblasting can achieve different reflections or matting at will. For example, the polishing of stainless steel workpieces and plastics, the polishing of jade, the matting of wooden furniture surfaces, the patterns on the frosted glass surfaces, and the texturing of cloth surfaces.

At the beginning of the design, the structural shape of the part needs to meet two major requirements, one is the design requirements, and the other is the process requirements. At the same time, the structural design of parts should not only consider industrial aesthetics and modeling, but also consider the possibility of technology. Most of the common structures on parts are obtained by casting (or forging) and machining, so they are called process structures. Understanding the common process structure of parts is the basis for learning part drawings. Casting process structure on parts 1. Cast fillet In order to facilitate the casting modeling, avoid sand falling from the sand mold corner when pulling out the mold from the sand mold, and wash the corner when pouring, and prevent the casting defects such as cracks, organizational porosity and shrinkage cavity from occurring at the corner of the casting, so the intersection of adjacent surfaces on the casting shall be made into rounded corners. For compression molded parts, the fillets can ensure that the raw materials are filled with the die, and it is convenient to take the parts out of the die. The casting fillet radius is generally 0.2-0.4 times of the wall thickness, which can be found in relevant standards. The fillet radius of the same casting shall be the same or close to each other. 2. Lifting angle During molding, in order to take the wood mold out of the sand mold, a certain slope is often designed on the inner and outer walls of the casting along the mold lifting direction, which is called the mold lifting slope (or casting slope). The mold lifting angle is usually 1:100-1:20. When expressed by angle, the wood pattern for manual modeling is 1 ° - 3 °, the metal pattern is 1 ° - 2 °, and the metal pattern for mechanism modeling is 0.5 ° - 1 °. Because there are casting fillets at the intersection of the casting surface, the intersection lines on the surface become less obvious. In order to distinguish different surfaces when looking at the drawing, the intersection lines in the drawing should still be drawn, which are usually called transition lines. The drawing method of transition line is basically the same as that of intersection line without fillet. 3. Casting wall thickness In order to ensure the casting quality of the castings, prevent the shrinkage cavity caused by the loose structure outside the wall thickness due to the different cooling and crystallization rates due to the uneven wall thickness, and the cracks at the thin and thick phases, the wall thickness of the castings shall be uniform or gradually changed to avoid sudden changes in wall thickness and local hypertrophy. The difference of wall thickness should not be too large, so the transition slope can be set at the intersection of two walls. The wall thickness may not be indicated in the drawing, but shall be indicated in the technical requirements. In order to facilitate mold making, molding, sand cleaning, removal of gating and riser and machining, the shape of castings shall be simplified as much as possible, the shape shall be straight as much as possible, and the concave convex structure shall be reduced on the inner wall. The casting with too thick thickness is easy to produce casting defects such as cracks and shrinkage cavities, but the casting with too thin thickness is not strong enough. In order to avoid the influence of thickness thinning on strength, reinforcing ribs can be used to compensate.