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

The machining of mechanical parts consists of several surfaces, and in order to study the relative relationship between the machined surfaces of the parts, a datum must be determined; the datum is the point, line and surface on the part that determines the position of other points, lines and surfaces. According to the different functions of the benchmark, the benchmark can be divided into two categories: design benchmark and process benchmark. Types of parts machining. Design benchmark: the benchmark used to determine the location of other points, lines and surfaces on the part drawing is called the design benchmark.   Process benchmark: the benchmark used in the process of parts processing and assembly is called the process benchmark. Process benchmark according to the different uses are divided into assembly benchmark, measurement benchmark and positioning benchmark.   (1) assembly benchmark: assembly used to determine the position of the part in the component or product benchmark is called the assembly benchmark.   (2) measurement benchmark: used to check the size and position of the processing surface benchmark called the measurement benchmark.   (3) positioning datum: the datum used to position the workpiece during processing, called the positioning datum. As a positioning reference surface (or line, point), in the first process can only choose the unprocessed rough surface, this positioning surface is called the rough benchmark. In each subsequent process can be used in the machined surface as a positioning reference, the positioning surface is called the fine reference. The development of process procedures. 1, the reference first: that is, the first processing reference surface. In the process of parts processing, should be processed first appearance as a positioning reference, in order to provide accurate benchmarks for the subsequent processes as soon as possible.   2, divided into processing stages: the processing quality requirements of the surface 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; easy to arrange the heat treatment process; and easy to find defects in the blank.   3, first face after the hole: for the box, bracket, connecting rod and other parts, should be processed first plane after processing holes. This can position the machined hole in the plane, to ensure the accuracy of the plane and hole position, and to bring convenience to the processing of the hole on the plane.   4, finishing process: 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 general principles of the development of precision parts processing process route.

In non-standard parts processing, there will be different understanding of high-precision processing and different definitions, so how to define the processing standards for non-standard parts processing? The definition of precision machining of non-standard parts is the production processing of the dimensions or characteristics of individual steel parts in accordance with the process and process flow, including the flatness of the steel parts, the surface finish layer, the flatness of the surface layer, the strength of the surface layer, so that the production and processing of the parts are possible. Accuracy and production processing performance exceeds the full range of engineering drawings specified. Non-standard parts processing flatness regulations are the dimensional tolerance regulations around the rectangular frame steel parts and other non-standard high-precision machined steel parts, the thickness of the four corners of the specified steel parts over a certain range of dimensional tolerances. If the precision measurement of the thickness of the four sides does not meet the dimensional tolerance requirements, it does not meet the flatness requirements, and the steel part needs to be readjusted. The problem will be in the glass suction cups of CNC grinding machines, which are damaged by excessive applications, causing deviations in flatness. It will be the grinding wheel piece is not rectified, or the grinding wheel piece is broken, this time hardware non-standard parts processing also need to replace the grinding wheel piece, but also again to clear the glass sucker, carefully remove the neat, to prevent the emergence of burrs.   Non-standard parts processing of flatness regulations, that is to say, the provisions of the side of the steel parts and road surface over the size tolerance regulations. Understand that is to say the cube, from the number axis seems to be divided into XYZ three sides, the general provisions of XZ, YZ exceed the size tolerance provisions. Appear deviation also and flatness provisions of basically the same. In the non-standard high precision machining flatness regulations generally in accordance with the provisions of the flatness to solve can.

What methods can be used to obtain dimensional accuracy when machining parts? In the machining process of precision parts, there are many factors that affect the machining accuracy. Different processing methods can achieve different precision under different processing conditions; if the pursuit of processing precision will reduce production efficiency and increase the processing cost of precision mechanical parts. Therefore, precision machining enterprises should strive to improve efficiency and reduce production costs under the premise of ensuring quality. The machining accuracy of precision mechanical parts can be divided into dimensional accuracy, shape accuracy and position accuracy. Therefore, the level of machining accuracy is measured by dimensional tolerance, shape tolerance and position tolerance. The method of obtaining the dimensional accuracy of the parts: test cutting method: first test cutting a small part of the machined surface, measuring the test cutting size, adjusting the position of the cutting edge of the tool relative to the workpiece to meet the processing requirements, and then test cutting measurement, test cutting measurement two or three times, when the precision machining dimensions meet the requirements, the entire surface to be machined for cutting. Machining precision mechanical parts of journal size test cutting turning, online measurement and grinding of journal size, test boring of box parts, manual fine grinding of precision measuring blocks, etc., all undergo test machining and shearing.   The accuracy achieved by the test cutting method can be very high, it does not require complex equipment, but it is time consuming and requires several adjustments, test cuts, measurements and calculations. The efficiency is low, depending on the technical water symptoms of workers and the accuracy of measuring instruments; the quality is unstable and only applicable to single-piece small batch production.   Adjustment method is to use samples or standard parts to pre-adjust the accurate relative position of machine tools, fixtures, tools and workpieces to ensure the dimensional accuracy of precision mechanical parts processing, the size of the parts remain unchanged during a batch of processing. . This is the adjustment method. Machining shaft parts on a multi-tool lathe or hexagonal automatic lathe, machining grooves on a milling machine, grinding external circles and hole systems on a centerless grinder are all adjustment methods.   If using milling machine fixture, the position of the tool is determined by the tool holder; the essence of the adjustment method is to use the fixed distance device or tool setting device or pre-set tool holder on the machine tool to make the tool reach a certain position relative to the machine tool or fixture. Accuracy, and then processing a batch of workpieces. In mass production, often use the travel limiter, prototype, prototype and other tool setting devices to adjust. The adjustment method has better machining accuracy and stability and higher productivity than the test cutting method. It does not require much operation of the machine tool, but the adjustment of the machine tool is very demanding. It is usually used for mass production and batch production. Fixed-size method: precision parts processing using the corresponding size of the tool to ensure that the workpiece processing part of the size of the method is called fixed-size method, that is, the use of standard size tools for processing, precision machining surface size by the following formula to determine the size of the tool; that is, the use of a certain size accuracy of the tool to ensure the accuracy of the workpiece being processed. For example, using a square broach to pull out a square hole, using a drill, reamer, reamer or boring block to process the inner hole, using a combination of milling cutters on both sides of the workpiece to mill a groove, etc., are all part of the sizing tool method.

First, cnc machining common causes of failure 1. Overload. Reasons: Excessive cutting volume, frequent forward and reverse rotation, spindle motor failure, spindle drive installation failure. 2. Spindle does not rotate. Reason: spindle drive installation failure, CNC installation can not output speed signal, spindle motor failure, spindle drive installation failure, drive belt breakage. 3. Spindle speed deviates from the command value. Reason: motor overload, CNC output spindle speed command output problem, speed measurement installation failure or speed response signal disconnection. 4. Spindle abnormal noise and vibration. Reason: common onset in the deceleration process, the spindle drive installation has problems, such as AC drive in the regeneration circuit failure. Second, cnc machining presents the reasons for overcutting 1. machining center arc processing overcut. In cnc machining stop internal summary arc processing, if the choice of tool radius rD is too large, beyond the required processing arc radius r, it is likely to attack overcutting. CNC machining program is based on the theoretical summary track of the workpiece is prepared, without thinking about the actual machining process tool movement track. Due to the presence of the tool radius, the actual track of the tool becomes coarse and does not coincide with the programmed track. In order to get the correct summary of the workpiece appearance, the tool radius compensation instruction needs to be applied to set between the tool track and the programmed track. Otherwise, overcutting of the workpiece is unpreventable. 2. Overshoot discrimination during linear machining. In cnc machining generalized by a straight line section of the workpiece, if the tool radius is too large, it is likely to present the phenomenon of overcutting, resulting in the failure of the workpiece. Can be programmed vector corresponds to the scalar product of the correction vector to discern the positive and negative.

A, mechanical parts machining arrangement should be based on the structure of the parts and blank situation, as well as the positioning clamping needs to think about, the focus is on the rigidity of the workpiece is not destroyed. 1. The processing of the previous process can not affect the positioning and clamping of the next process, the intersection of general mechanical parts processing process should also be considered. 2. First stop the internal shape of the cavity plus process, and then stop the shape of the processing process. 3. The same positioning, clamping or the same knife processing process is best articulated to stop, in order to reduce the number of repeated positioning, the number of tool changes and the number of times to move the platen. 4. mechanical parts processing in the same device to stop multiple processes, should be arranged first on the workpiece rigid destruction of small processes. Second, the tool concentration division method: Is divided into processes according to the tool used, with the same tool to finish processing all parts on the part can be completed. In the second knife, the third to complete the other parts they can complete. This can reduce the number of tool changes, tighten the empty range time, reduce the unnecessary positioning error. Third, to process parts in order method: On the processing content of many parts, according to its structural characteristics of the processing part into several parts, such as internal shape, shape, surface or plane. General first processing plane, positioning surface, after processing holes; first processing simple geometric shape, and then processing complex geometric shape; first processing lower precision parts, and then processing higher precision requirements of the parts.

1, the geometry of the parts shape and mutual bit precision to do μm or angle second level. 2, parts of the boundary or characteristics of the standard tolerance in μm below 3, parts surface external economic unevenness city (surface unevenness city mean relative height difference) is less than 0.1 μm 4, mutual parts can achieve the provisions of the fit force. 5, part of the parts can also reach the precise structural mechanics or other physical characteristics of the provisions, such as floating ball cell phone gyroscope torsion bar of the twist bending stiffness, winding components stiffness coefficient, etc. Precision mechanical equipment processing is in the strictly controlled natural environment, the application of precision CNC lathe and precision measuring instruments and gauges to complete. Processing precision to and beyond 0.1μm is called ultra-precision machinery and equipment processing. In the aerospace manufacturing industry, precision machinery and equipment machining is mainly used to process precision machinery and equipment parts in the control system of four-axis aircraft, such as precision mutual fit parts in the hydraulic machine and pneumatic servo mechanism, the structure and shell of cell phone gyroscope, steam float, liquid float rolling bearing parts and floating ball, etc. The construction of precision parts for quadcopter is tedious, the bending stiffness is small, the prescribed precision is high, and the proportion of difficult to machine raw materials is relatively large.

CNC milling machine processing often encounter many parts need surface processing treatment, in the surface processing will also have high precision requirements. High-precision processing often requires multiple processes on the surface to improve the surface smoothness. Therefore, before arranging the process must capture the surface high-precision processing main process. CNC milling machine processing center needs to arrange the process and processing stage division reasonably, the necessary principle of rough first and then fine, first surface and then hole. 1、Rough machining stage In the machining process of engine block, arrange roughing process to rough the blank comprehensively and cut off most of the residual to ensure production efficiency. 2、Semi-finishing stage In the engine block machining, in order to ensure the machining accuracy of some important surfaces, arrange some semi-finishing processes, the accuracy and surface roughness requirements of some medium surface machining is completed, and the requirements of high surface semi-finishing machining, for the future preparation of finishing. 3、Finishing stage The surface with high requirements for precision and surface roughness is processed. 4、The processing of minor small surfaces Such as threaded holes, CNC milling machine machining center can be carried out after finishing the main surface, on the one hand, the processing of the workpiece deformation does not affect much, while the scrap rate is also reduced; in addition, if the main surface out of scrap, these small surfaces do not need to be processed, thus avoiding wasted man-hours. However, if the processing of the small surface is easy to touch the main surface, it should be placed on the small surface processing before the main surface finishing. 5, auxiliary processes should also be properly arranged Such as the inspection process, after the roughing stage of the parts, key processes before and after processing, after the parts are all processed, should be properly arranged. CNC milling machine machining center on the processing stage division, has the following benefits: First, you can take measures to eliminate internal stresses in the workpiece after rough machining to ensure accuracy; Second, finishing in the back, not to damage the workpiece in the process of transport of their own processing surface; Again, first rough machining of each side, you can find early defects in the blank and timely processing, will not waste time. But for the general small workpiece should not be divided into very fine.

In the process of work, the problem of failure is very normal, so we should not be too surprised when we meet the failure, want to avoid more failures, then we have to do a good job of maintenance outside the work, many new users do not know what to do when they encounter failures, want to solve the problem, we must first find the source of the problem, the following together to understand the causes of large cnc What are the reasons for the failure of processing? 1, may be the reason for the tool, sometimes it is not our operation what went wrong, but the problem of accessories, because the tool is not sharp enough, not strong enough, etc. These reasons will lead to broken knives. 2、It is also because of the material problem, when the aluminum alloy shell is not uniform enough, uneven hardness and softness, or too many impurities will also lead to the occurrence of the problem. 3, the problem of clamping, we have to see whether the aluminum alloy shell is firmly clamped; whether the fixture is locked. These reasons are worth our attention. 4, there is the machine tool problem. CNC machining machine tool is level; voltage is stable; machine screw is aging and other such reasons 5, the preparation of the program, the preparation of aluminum alloy shell processing program, the spindle motor speed is too low; eating tool amount is too large; machining allowance is reasonable; aluminum chip discharge is smooth.

Turn-mill CNC machine tool is a typical high precision, high efficiency, high rigidity, high automation and high flexibility turn-mill compound center. Turn-mill compound CNC lathe is an advanced compound machine consisting of five-axis linked milling machining center and double spindle lathe. It provides a better solution for processing small parts with high precision, high quality and high complexity. With the rapid development of science and technology in the world, many products are developing in the direction of precision, miniaturization and light weight. Many small precision CNC machine tools are often required to meet the needs of users. In the current Chinese machine tool products, there is a lack of such precision CNC machine tools. In addition to widely used in the watch industry, medical equipment, automotive parts manufacturing and other light industry, but also for aerospace, weapons, ships and other defense and military fields to process many precision special parts, such as flight control gyro, air-to-air missile inertial navigation and other zero position machine, is the market for small precision complex parts of high quality machine tools. Turn-mill machining center has no special requirements for the machine tool, but must provide at least one Y-axis movement. The rotation of the workpiece provides the c-axis motion for the milling cutter to transfer the required feed rate (power). However, the cutting speed of the workpiece is measured using the IPM rather than the SPM of the lathe (this means that the workpiece is cutting at a much lower speed on the mill-turn machining center than it would during turning). But the y-axis motion is necessary because the milling tool has to do a lot of eccentric machining. Also, when the tool is eccentric, it cannot machine to the desired part size because when the tool is centered, the center of the tool intersects the center of rotation of the part, so the tool can only cut with its end face (i.e., it cannot Cutting edge. To ensure that the cutting edge can cut correctly, the tool centerline must deviate from the part's center of rotation line to 1/4 of the tool diameter. Turning and milling machining centers can effectively use the following three types of tools. The main reason is the use of wiper blades or scrapers. For end mills in turning and milling, large size flat or heavy interrupted cuts can be made. Blade end mills are used for step milling. Integral end mills are used for machining cylindrical parts and precision milling of deep and narrow grooves. Using the scraper structure of the above tools, it is possible to cut deep parts by two of the four cutting edges of the tool, thus achieving high efficiency and high precision machining. However, using this method, problems occur when the tool approaches the sides of steps and recesses. In this case, the eccentric tool leaves many rounded corners on the surface of the part after machining. In order to remove these rounded corners, the tool must be machined again. In this case, the tool deviation is no longer required and the tool is moved along the Y-axis to the center of the part for machining. However, in some machining steps this machining allowance is not allowed (sometimes metal is not allowed). One of the unsatisfactory facts of turning and milling center machining is the shape error of the machined part. When the milling cutter is milled around the part, some scalloped marks will inevitably form on the part surface at regular intervals. This error cannot be completely eliminated, but can be effectively controlled with a wiper blade. A trimming insert follows the other inserts so that the cutting edge is slightly convex in the width direction, so that the blade of the insert extends just to the surface of the part being machined, creating a new cutting surface with a slight scalloped trace smooth.

For precision parts, the processing is very strict, the processing process has a tool in, tool out, etc.. For the size of specific requirements, precision requirements, such as 1mm plus or minus how many microns, etc., if the size of the wrong too much will become scrap, then the equivalent of having to re-processing, time-consuming and laborious, and sometimes even make the entire processing material scrap, which causes an increase in costs, at the same time, the parts are certainly not available. For precision parts processing is mainly dimensional requirements, such as how much the cylindrical diameter, there are strict requirements, positive and negative error within the specified requirements to be qualified parts, otherwise they are unqualified parts; length, width and height also have specific strict requirements, positive and negative errors are also specified, such as an embedded cylinder (take the most simple basic parts for example), if the diameter is too large, more than the error allowed range, it will Caused by, insert not into the situation, if the actual diameter is too small, more than the lower limit of the negative value of the error allowed, it will cause inserted too loose, not solid problems occur. These are unqualified products, or the cylindrical length is too long or too short, beyond the error tolerance range, are unqualified products, are to be scrapped, or reprocessed, which will inevitably cause an increase in costs. Precision parts processing requirements is in fact the main size problem, must be strictly in accordance with another plus drawings for processing, processing out of the actual size will certainly not be the same as the theoretical size of the drawings, only, as long as the processing size within the error tolerance is qualified parts, so the requirements of precision parts processing is in strict accordance with the theoretical size for processing. Second is the advanced precision parts processing equipment and testing equipment, advanced processing equipment makes processing precision parts easier, higher precision, better results. Testing equipment can detect the parts that do not meet the requirements, so that all the products sent to customers really meet the requirements.