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

A turned part is simply a part that is machined on a lathe using a CNC lathe. It is through the rotary motion between the workpiece and the linear or curved motion between the tools to change the shape and size of the blank into parts that meet the requirements of the drawings. Turning is the most common cutting method, suitable for most of the workpiece processing, can achieve high precision, there are many types of turning parts, of which hard turning is the most famous for high thermal stability, but also the most widely used. So let's learn more about hard turning. Choosing the right hard turning system can reduce or even eliminate the high cost and processing time, while achieving high accuracy and thus maximizing the utilization of equipment. So when choosing a reasonable turning part we have to take into account the following factors.   1, coolant. No coolant cutting has a cost advantage, but in continuous cutting, coolant can improve the smoothness of the surface while extending the life of the tool, and the use of coolant to water-based. Take away most of the heat in the cutting process, to protect the machine while also avoiding operator burns.   2, whitening layer. Also called heat-affected zone, in the process of cutting, due to excessive heat transfer to the parts, whitening layer is often formed on the bearing steel, so the operator to randomly spot-check, to determine how many parts each insert can turn without forming a whitening layer.   3, machine tools. The stiffness of the machine largely determines the machining accuracy of hard cutting. In order to keep all parts as close as possible to the turret holder to maintain systematic, to minimize overhang, tool extension and parts out and eliminate the strip gap pieces and washers.   4、Turning threads. The use of appropriate inserts is key, the best being triangular inserts. Properly increase the number of tools and reduce the depth of cut, while the use of alternate side cutting can control the cutting force and extend the life of the tool. 5, workpiece. The most suitable for hard turning parts have a small length to diameter ratio (L/D), generally speaking, the ratio of L/D of unsupported workpiece is not more than 4:1, supported workpiece L/D ratio is not more than 8:1. Although slender parts have tailstock support, but due to excessive cutting pressure may still cause tool vibration. In order to maximize the rigidity of the system for hard turning, the overhang should be minimized. Tool extension length should not be greater than 1.5 times the height of the tool bar.   6、Boring. Boring hardened materials requires a lot of cutting pressure, so it is often necessary to multiply the torsional and tangential forces on the boring bar. The use of positive front angle (35 ° or 55 °), small tip radius inserts can reduce the cutting pressure. In increasing the cutting speed while reducing the depth of cut and feed rate, is also a way to reduce cutting pressure.   7, process. Because most of the heat generated by hard turning is carried away by the chips, inspection of the chips before and after processing can find out whether the whole process is coordinated. Continuous cutting, the chip should be blazing orange, and like a ribbon like floating out. If the chips are cooled and a basic break with the hand, indicating that the heat taken away by the chips is normal.   8, inserts. CBN inserts are the most suitable for hard turning, despite its expensive, but its continuous cutting process can provide the safest tool wear rate, relative to ceramic or metal ceramic inserts are far ahead of the performance.

Turning parts machining procedure is a very important process in the parts processing, need to follow certain principles of machining, we will analyze the turning parts machining steps in accordance with the operation before, during and after the operation. First, before the operation   1, the operator must be strictly in accordance with the operating rules to wear the relevant protective equipment, etc..   2, the operator should check whether the electrical parts are normal before the operation, to make sure there is no problem before starting.   Second, during operation   1, to ensure that the operation of workpiece clamping firm, such as tools, work, clamps and other workpieces.   2, all types of machine tools should be turned on after the first low-speed idle, to ensure that there is no problem before you can carry out operations.   3, the machine table is strictly prohibited to put other irrelevant things.   4, the operator should not use their hands to remove the excess iron chips, should use special tools to clean up, and to stand in a safe position to avoid splashing iron chips when the machine tool is in motion.   5, in the operation of the machine tool, the operator is prohibited to adjust the transmission or change the operating stroke, not to touch the working surface in processing with their hands, not to measure the size in operation again, not to pass items across the machine drive part.   6, in the processing process, to strictly comply with the operating rules, do not leave the work station when the machine is running, leave the need to cut off the power, adjust the speed, stroke, tool, etc. to stop, not in the machine running. Third, after the operation   1, after the completion of operations need to cut off the power supply, remove the tool, the various parts of the handle are set back to neutral, and lock the electrical switch box.   2, clean up the equipment, such as iron chips, and lubricant into the guide rail to prevent rusting.  

The positioning accuracy compensation of turning milling machine tool Whether the turning milling compound machining machine tool can meet the requirements of machining accuracy, in addition to geometric accuracy testing, it is also necessary to test the positioning accuracy of the machine tool. The main reason for the formation of the positioning error of the machine tool is the screw error and reverse clearance of the CNC machine tool. The screw pitch error compensation is mainly to compensate the system error, which can improve the positioning accuracy of the machine tool, the repetitive positioning accuracy and the reverse error of the drive screw movement. The movement and positioning accuracy of the main components before the reconfigurable machine tool configuration meet the requirements of design and processing. In order to meet the accuracy requirements after the reconfigurable machine tool configuration, it is necessary to measure the reverse clearance and repeated positioning accuracy of the reconfigurable machine tool to obtain the accuracy data after the reconfigurable machine tool configuration, so as to compensate it. Based on the above idea, the laser interferometer is used to measure the motion axis error, For the results of positioning accuracy detection, such as reverse clearance and complex positioning accuracy, the CNC machine tool is compensated for accuracy through the pitch error and reverse clearance compensation function of the retractable configuration machine tool controller, so that the positioning taper is significantly improved. For turning milling compound machining machine tools equipped with Y-axis components, the inspection items to be carried out mainly include: Z-axis positioning accuracy and dare to repeat positioning accuracy detection, X-axis positioning accuracy and repeat positioning accuracy detection, Y-axis positioning accuracy and coin duplicate positioning accuracy detection, etc. Because the Z-axis stiffness is large, or the new configuration will not cause a large change in the positioning tip, the positioning accuracy detection of the Z-axis can be stopped after the configuration, so only the accuracy change caused by the reconfigurable positioning accuracy of the X-axis and Y-axis is studied. The basic principle of software compensation for micro turning milling compound machine tool is that in the machine coordinate system, without compensation, the measuring stroke is divided into several equal segments within the axis measuring stroke, the average position deviation of each target position is measured, and the average position deviation is inversely superimposed on the interpolation command of the digital control system. The pitch error compensation includes unidirectional compensation and bidirectional compensation. The unidirectional compensation uses the same data compensation for the forward and reverse movement of the feed axis, and the bidirectional compensation uses different data compensation for the forward and reverse movement of the feed axis. The CNC system of turning milling compound machining center adopts one-way skimming error compensation. In the numerical control system, the reverse clearance is compensated mainly by setting the parameters of the reverse clearance. The reverse clearance compensation is effective when the coordinate axis is in any mode. After the compensation of the screw pitch error of the lead screw, measure the maximum positioning error, and then analyze the positioning error, repeated positioning error, position dispersion and other accuracy indicators. If they exceed the standard, continue to modify the compensation data, and finally make the extruding degree meet the standard. The error measurement and compensation steps are as follows: (l) Installation and commissioning of high-precision displacement measurement device; (2) According to the national standard, the measuring program shall be prepared. During the whole journey, the measuring points shall be positioned at evenly spaced locations; (3) Record the actual accurate position of the operation to these points; (4) Mark the errors at each point to form an error table in different command bit basins; (5) Input the error table into the CNC system and compensate according to the error table.

Advantages and Disadvantages of Turning Milling Composite Machining Process for Micro Parts The turning milling compound machining of micro structural parts is a highly intensive process, which embodies the basic characteristics of complete machining. That is, all processing procedures of a part should be arranged on one machine tool as far as possible, and the number of repeated positioning and clamping should be reduced. Complete machining is first to reduce the auxiliary time of the process, improve the processing efficiency, and ensure a certain batch production capacity. More importantly, it is to avoid the machining error of parts due to the loss of coordinate information caused by dare to re clamp. Therefore, studying the complete machining process is an important way to improve the machining accuracy of parts. In the micro mechanical turning milling composite processing, the role of machining process planning can not be ignored. Process planning includes clamping planning, processing method selection and process sequence planning. Process sequence planning is the most critical link in process planning: the process planning problem of micro turning milling parts is also the problem of determining the cutting removal sequence of different structural characteristics. Different removal sequences not only affect the processing accuracy The processing efficiency and cost also affect the stability of the processing technology of the parts and the subsequent use performance of the parts. In addition, excellent, efficient and high-precision machining quality is often achieved by advanced processing technology and auxiliary related technologies. For example, in the processing of micro and small parts, the wear or damage of micro and small tools directly affects the processing quality of the parts, so it is necessary to carry out research on the wear rules of tools and wear and damage detection technology; The research on the surface roughness of micro parts and the optimization method of process parameters can better meet the processing requirements of high-precision and high-efficiency micro complex structural parts only by solving the key technology of turning milling composite processing technology.

Why do small structural parts need to be processed by car milling The complex and small structure features require that the turning milling compound processing can be completed after one clamping. The reasons are as follows: (l) In the process of processing small parts, it is necessary to pick up the lead and multiply when the process is changed between machine tools. Picking up and re clamping will cause the loss of coordinate information, and this part of clamping error will lead to the processing error of parts: (2) The functional surfaces are small, and the local structural characteristics of some parts have low stiffness and strength. Multiple positioning and clamping are not only unreliable but also easy to cause deformation, which may lead to loss of machining accuracy in the light, or even damage or even scrap the parts in the serious. To sum up, it is better to process small parts completely. The so-called complete processing is to complete all the processing procedures of complex parts on one machine tool. The complete processing is integrated through the technological process, and the processing process of a part can be completed in one clamping. As the clamping times are reduced, the accumulation of multiple positioning errors is avoided, the machining accuracy, high reliability of the machining process and zero defect production are improved. In addition, the complete turning milling composite processing saves multiple clamping and positioning time, shortens the auxiliary time between the processing chain and each process, reduces the number of machine tools, simplifies the material flow, greatly shortens the processing time, improves the production efficiency, improves the flexibility of the production equipment, reduces the total production area, and makes the investment more effective.

What role does the division of processing stages play in precision parts processing The division of processing stages of precision parts should not be absolute, but should be flexibly controlled according to the quality requirements, structural characteristics and production guidelines of parts. 1. To ensure the processing quality. When the workpiece is rough machined, the removed metal layer is thicker, the cutting force and clamping force are larger, and the cutting temperature is higher, which will cause greater deformation. If the processing stages are not divided, and the rough machining and finish machining are mixed together, the processing errors caused by the above reasons cannot be avoided. According to the processing stage, the processing error caused by rough machining can be corrected by semi finishing and finishing, so as to ensure the processing quality of parts. 2. Use the equipment reasonably. The rough machining allowance is large, the cutting amount is large, and the machine tools with large power, good rigidity, high efficiency but low accuracy can be used. The precision machining has small cutting force and little damage to the machine tool. Use high-precision machine tools. This gives full play to the respective characteristics of the equipment, which can not only improve the processing productivity of precision parts, but also extend the service life of precision equipment. 3. It is convenient to find blank defects in time. Various defects of the blank, such as porosity, sand inclusion and insufficient allowance of the casting, can be found after rough machining to facilitate timely repair or scrapping, so as to avoid further processing and waste. 4. It is convenient to arrange the heat treatment process. For example, after rough machining, stress relief heat treatment is generally arranged to eliminate internal stress. Final heat treatment such as quenching shall be arranged before finishing, and its deformation can be eliminated by finishing. When the processing quality of precision parts is not high, the rigidity of the workpiece is good, the precision of the blank is high, the machining allowance is small, and the production process is not large, so there is no need to divide the processing stages. For heavy workpieces with good stiffness, because clamping and transportation are time-consuming, all rough machining and finishing are usually completed in one clamping. For the workpieces that are not divided into processing stages, in order to reduce the influence of various deformations during rough machining on the processing quality, after rough machining, loosen the clamping mechanism and keep it for a period of time to make the workpieces completely deformed, then use less after heating, re clamp the clamping force and complete the processing.

Analysis of Three Machining Routes for Machining Groove of Precision Parts In precision parts processing, there are plane processing, hole processing, etc., but do you know the groove processing? The groove processing should be difficult to process and also requires high cutting tools. 1. For grooves with relatively small width and depth values and low accuracy requirements, a tool with the same width as the groove can be directly cut into a one-time molding method. After the tool cuts into the low groove, the delay command can be used to make the tool stay for a short time. The low roundness of the groove can be trimmed, and the tool feed speed can be used when withdrawing the tool. 2. For deep groove parts with small width value but large depth value, in order to avoid too high forward pressure of the tool and tool damage due to poor chip removal during grooving, feed by stages shall be adopted. In this method, after the cutter cuts into the workpiece to a certain depth, the precision part processing stops feeding and returns to a certain distance to achieve the purpose of chip breaking and chip removal. At the same time, try to select a tool with higher strength. 3. For wide groove cutting, in order to cut a wide groove, a groove wider than the tool width is usually called a wide groove. The width and depth of the wide groove have relatively high precision requirements and surface quality. When cutting wide grooves, generally use a row of tools for rough machining, and then use a fine grooving knife to cut one side of the groove until the groove is low, while the height of the finishing groove is the same as that of the other side of the groove, and then exit along the side. Therefore, when precision parts are processing part grooves, the most important thing to pay attention to is the coaxiality and symmetry of the groove. Some problems about the groove depth are not serious, but the width of the keyway must be guaranteed, and the width must not be large.

What kind of tool wear will occur in the process of turning and milling In turning milling compound machining, tool wear is often caused by one main reason and combined action. Under different processing conditions, the main factors that cause tool wear are different, mainly including the following: 1. Abrasive wear In the cutting process, the chip, some smile hard spots with high hardness in the workpiece material, such as the first level chip buildup, can carve grooves of different depths on the tool surface. This is hard spot wear, also known as abrasive wear. When high-speed steel end milling cutter is used for turning and milling process, because the hardness of high-speed steel cutter is not high compared with that of cemented carbide cutter, the cutting speed is low, and the heat resistance is poor, when the turning milling composite processing is not at high cutting temperature, abrasive wear becomes the most significant wear reason for high-speed steel cutter. 2. Diffusion wear At high cutting temperature, the tool surface contacts with the workpiece and chip surface, and the chemical elements of the tool and workpiece diffuse to each other, changing the composition and structure of the original material, weakening the performance of the tool material, and accelerating the wear process. Diffusion wear mainly occurs in high-speed cutting, so the cutting temperature is very high and the element diffusion rate is high. At the same time, with the increase of cutting speed, the degree of diffusion wear increases. 3. Oxidation wear Slight oxidation of tool surface is beneficial to reduce tool wear, because the existence of oxide film can avoid direct contact between tool chip and tool workpiece, thus reducing adhesion. However, when the cutting temperature is high, the oxidation of tool materials will be very intense, forming a series of soft oxides. These oxides are stolen by chips or workpieces, resulting in the loss of tool materials, which constitutes oxidation wear in turning milling composite processing

What are the three wear states of end milling cutter for turning milling In turning milling compound machining, the wear of the rear face of the end mill mainly includes the wear of the main rear face and the wear of the auxiliary rear face. The wear of the rear tool surface is caused by the strong friction in the tool workpiece contact area, and there are obvious signs of mechanical friction in the wear area. 1. Uniform wear of main and rear cutter faces During turning and milling, the wear of the main and rear tool surfaces is an equal width wear band at the initial stage of wear, and extends on the rear tool surface adjacent to the entire cutting edge. Figure (a) is the schematic diagram of uniform rear tool surface wear. The width of this wear band is called VB, which is a commonly used wear evaluation index. The wear of the rear face will intensify the cutting friction in turning and milling, increase the cutting force, increase the cutting temperature and reduce the processing quality. Figure (b) shows the actual wear effect of the main and rear face of the end mill at the initial wear stage. 2. Local wear of main and rear cutter faces Among the end milling cutters tested, a part of the cutters have serious wear in the local range of the main and rear cutter surfaces, and develop in this specific part. Figure (c) shows the local wear of the main and rear cutter surfaces of the neutral milling cutter for turning and milling. This wear pattern is caused by the friction between the peripheral edge and the surface to be machined of the workpiece in the turning milling composite processing, and the deep grooves are grinded. The local wear of the rear tool surface generally occurs in the middle and later stages of turning milling processing. 3. Wear of auxiliary rear cutter face In turn milling process, the auxiliary cutting edge is the end face edge of the end mill. Because the workpiece is also rotating during the machining process, the contact frequency between the flank and the machined surface becomes faster, so the flank wear in turning milling process is much more serious than that in ordinary milling. Figure (d) shows the wear of the rear tool face of the pair in turning milling composite processing.

Dull standard of end milling cutter for small turning milling compound machining When the end milling cutter is worn to a certain limit, it cannot be used for small turning milling combined processing. This wear limit is called the bluntness standard. The blunting standard of end milling cutter shall be formulated mainly based on the specific conditions of turning and milling and the requirements for processing quality. Specifically, the following principles shall be met: 1. The bluntness standard of small diameter end milling cutter should not exceed the critical value of severe tool wear; 2. When the rigidity of the process system is poor, a smaller blunt standard shall be specified; 3. When turning and milling work-piece materials with poor heat resistance or temperature rise sensitive to wear, the bluntness standard shall be appropriately reduced; 4. When the machining accuracy and surface requirements are high, the blunt standard shall be reduced. If the blunting standard is too large, it will lead to excessive cutting force, which will aggravate the deformation and vibration of the process system, and therefore cannot meet the quality requirements of turning milling composite processing. Therefore, on the basis of these principles, the dulling standard should be increased as much as possible in order to make full use of tools and improve tool durability.