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

CNC lathe is a kind of precision mechanical parts processing commonly used, CNC lathe processing materials are usually used for easy cutting steel and copper, easy cutting steel containing sulfur S and phosphorus P higher material, sulfur and manganese in steel is in the form of manganese sulfide, and manganese sulfide in steel plays a role of lubrication, making steel easier to cut, thereby improving the production progress of the lathe. Then what do you need to pay attention to when machining precision mechanical parts? 1、When correcting the workpiece. Only allowed to use the hand plate to move the chuck or open the lowest speed to find the righting, not allowed to open the high speed to find the righting. 2、Change the spindle rotation direction. To stop the spindle first, not allowed to suddenly change the direction of rotation. 3、When loading and unloading the chuck. Only allowed to use the hand to turn the v-belt drive spindle rotation line, absolutely prohibit the direct drive machine to force loosening or tightening. At the same time to pad a board on the bed, to prevent accidents. 4, tool installation. Should not extend too long, the shim should be level, the width and the width of the bottom surface of the tool consistent. 5, hardware parts processing in. Not allowed to open the reverse car method to brake the spindle rotation. 6、Rotary type hexagonal lathe. (1) Not allowed to process bent and rough surface bar material. (2) When loading material, the material head must be aligned with the chuck hole and gently struck into it, and no messy knocking is allowed. 7、Program-controlled turning lap lathe. Pre-selection of spindle speed, tool holder feed, tool holder trajectory and continuous overrun according to the requirements of precision hardware parts processing process. Put the electric knob in the position of "adjusting" for test drive, and after confirming that there is no problem, then put the electric rotary in the automatic or semi-automatic position for work.

In the process of non-standard parts machining, the foundation is the most important, precision mechanical parts processing is the same, always first processing the fine reference, and then use the fine reference positioning processing other surfaces. Next we will put me some details.   For the box parts, generally is the main hole for the rough benchmark processing plane, and then the plane for the fine benchmark processing hole system; for shaft parts, generally is the outer circle for the rough benchmark processing center hole, and then the center hole for the fine benchmark processing outer circle, end face and other surfaces. If there are several fine benchmark, it should be in accordance with the order of benchmark conversion and gradually improve the processing accuracy of the principle to arrange the base surface and the main surface processing. For workpieces such as box, bracket and connecting rod, the plane should be machined first and then the hole. Because the contour of the plane is flat and large area, machining the plane first and then machining the hole with plane positioning can ensure that the hole has a stable and reliable positioning datum during machining, and is also conducive to ensuring the position accuracy requirements between the hole and the plane.   A part is usually composed of multiple surfaces, the processing of each surface generally need to be carried out in stages. In the arrangement of precision mechanical parts processing sequence, should first focus on the arrangement of the surface of the rough machining, in the middle according to the need to arrange in turn semi-finishing machining, and finally arrange finishing and finishing machining. For high precision requirements of the workpiece, in order to reduce the deformation caused by rough machining on the impact of finishing, usually rough and finish machining should not be carried out continuously, but in stages, interval appropriate time. The general principle of non-standard parts processing cutting process arrangement is: the work in front must be ready for the work behind, lay a good foundation and good service. Non-standard parts processing specific working principles can be divided into four areas.   The main surface of the part is generally processing accuracy or surface quality requirements are relatively high surface, their processing quality is good or bad to the quality of the whole part has a great impact, its processing procedures are often more, so the main surface processing should be arranged first, and then other surface processing is properly arranged in the middle of them interspersed. Usually the assembly base surface, work surface, etc. as the main surface, and the keyway, fastening with the light hole and screw hole as a secondary surface

In order to improve the quality of precision machining, to identify the main factors causing processing errors (original error) is the key, however, how to take the appropriate process technology measures to control or reduce the impact of these factors? The following editor will work with you to understand how to effectively improve the quality of precision machining six methods. First, error grouping method   This method reported gross bad or the previous process processing work size is measured according to the size of the error into n groups, each group of workpiece size error range is reduced to the original indeed / n; and then according to the error range of each group respectively adjust the position of the tool relative to the workpiece, so that the name group of workpiece size dispersion range center is basically the same. So that the size dispersion range of the whole batch of workpiece is greatly reduced. This method is often more economical and easy to use than to improve the vigilance of the gross bad precision snow. Such as in the finishing tooth shape, in order to ensure that the coaxiality of the gear ring and gear bore after processing, should reduce the gear inside also with the mandrel of the fit clearance. In the production is often grouped according to the size of the gear inside also, and then with the corresponding grouping mandrel, which evenly divided the original error due to the gap, improve the position of the gear ring accuracy of vigilance.   Second, the error compensation method   This method is to artificially create a new original error, support offset the original process system inherent in the original error, so as to achieve the purpose of reducing the processing error, processing accuracy.   Third, the error transfer method   This method is essentially the geometric error of the process system, force deformation and thermal deformation, etc. to transfer to the direction that does not affect the machining accuracy. For example, for multi-station processes with indexing or indexing or processes using indexing tool holders, the indexing and indexing errors will directly affect the machining accuracy of the relevant surface of the part. Fourth, the error equalization method   This method uses closely linked surfaces to each other, mutual correction, or use each other as a benchmark for processing. It can make those local larger error more uniformly affected the entire processing surface, so that the processing error transmitted to the surface of the workpiece is more uniform, and thus the workpiece processing accuracy is greatly improved accordingly.   Five, in situ processing method   In the processing and equipment with some precision involved in the interrelationship between parts, quite complex. If you focus on improving the precision of the parts themselves, sometimes not only difficult or even impossible, and the use of in situ processing hair can solve this problem. The main point of in-situ machining hair: to ensure what kind of position relationship between the parts, on such a position relationship using a part mounted on a tool to process a part. For example, in the manufacture of hexagonal lathes, the axis of the six large holes on the turret mounted tool holder must ensure that the machine tool and spindle rotation line overlap, the end face of the large holes and must be perpendicular to the spindle rotation line.   Six, direct error reduction method   This method is widely used in the production of a basic method. The method is to identify the main original error factors affecting machining accuracy, and then try to eliminate or reduce it directly. For example, the turning of long and thin shafts, due to the force and heat, causes the work to bend and deform. Now the "big straight tool reverse cutting method" is adopted, which basically eliminates the bending caused by cutting force. Supplemented by a spring tip, the harm of thermal elongation can be further eliminated.

Machining accuracy is the degree of conformity between the actual geometric parameters (size, shape and position) of the part after machining and the ideal geometric parameters. In machining, errors are inevitable, but the errors must be within the permissible range. Through error analysis, we can grasp the basic law of its change, so as to take corresponding measures to reduce machining errors and improve machining accuracy. Then there will be an error will be the reason, the reasons for it we summarized, there are roughly the following points.   1, spindle rotation error. Spindle rotation error refers to the actual axis of rotation of the spindle at each instant relative to its average axis of rotation of the amount of change. The main reasons for the spindle radial slewing error are: the coaxiality error of the spindle journals, the various errors in the bearings themselves, the coaxiality error between the bearings, spindle deflection, etc.   2, guide error. Guide rail is a machine tool to determine the relative position of the machine components of the benchmark, but also the benchmark of the machine tool movement. Uneven wear and installation quality of the guide rail, is also an important factor causing the error of the guide rail.   3, the transmission chain error. Transmission error of the transmission chain is the error of the relative motion between the first and last two transmission elements in the transmission chain of the inner contact. Transmission error is caused by the manufacturing and assembly errors of each component link in the transmission chain and wear and tear in the process of use.   4, the geometric error of the tool. Any tool in the cutting process, it is inevitable to produce wear and tear, and the resulting change in the size and shape of the workpiece. 5, positioning errors. First, the benchmark does not overlap error. In the parts used to determine a surface size, location based on the benchmark called the design benchmark. In the process diagram used to determine the size and location of the processed surface of the process based on the benchmark called the process benchmark. In the machine tool for processing the workpiece, you need to select a number of geometric elements on the workpiece as the positioning reference for processing, if the positioning reference selected does not overlap with the design reference, it will produce the reference does not overlap error. Second, the positioning vice manufacturing inaccuracy error.   6, the process system deformation of the error generated by the force. First, the workpiece stiffness. Process system if the workpiece stiffness is relatively low compared to the machine tool, tool, fixture, under the action of cutting force, the workpiece due to insufficient stiffness and deformation caused by the impact on the machining accuracy is relatively large. Second, the tool stiffness. External turning tool stiffness in the direction of the processing surface normal is large, its deformation can be negligible. Boring smaller diameter bore, tool bar stiffness is very poor, tool bar deformation on the hole processing accuracy has a great impact. Third, the stiffness of the machine tool components. Machine parts by many parts, machine parts stiffness so far there is no suitable simple calculation method, or mainly with experimental methods to determine the stiffness of machine parts.   7, the process system caused by thermal deformation of the error. Process system heat deformation on the impact of machining accuracy is relatively large, especially in precision machining and large parts processing, processing errors caused by heat deformation can sometimes account for 50% of the total error of the workpiece.   8, adjustment error. In each process of machining, the process system should always be adjusted in one way or another. Because the adjustment is not absolutely accurate, thus generating adjustment errors. In the process system, the workpiece, tool in the machine tool mutual position accuracy, is through the adjustment of the machine tool, tool, fixture or workpiece, etc. to ensure. When the machine tool, tool, fixture and workpiece blanks, such as the original accuracy of the process requirements and do not take into account the dynamic factors, the impact of the adjustment error, the processing accuracy plays a decisive role.   9, measurement error. Parts in processing or measurement after processing, due to the measurement method, gauge accuracy, as well as the workpiece and subjective and objective factors have a direct impact on the measurement accuracy.

What is precision machining? It is a process of changing the external dimensions or properties of a workpiece with machining machinery. It can be divided into cold machining and hot machining.   Cold machining is generally done at room temperature and does not cause chemical or physical changes in the workpiece. Processing at a temperature higher or lower than room temperature generally causes chemical or physical changes in the workpiece and is called thermal processing. Cold machining can be divided into cutting and pressure machining according to the difference of processing methods. Hot working commonly includes heat treatment, forging, casting and welding. The process effects of precision machining are as follows.   1, the geometry and mutual position accuracy of the part to micron or arc second level ;   2, the boundaries of the part or feature size tolerance in microns or less;   3, the part surface microscopic unevenness (surface unevenness average height difference) is less than 0.1 micron;   4, the mutual parts can meet the requirements of the fit force;   5, some parts can also meet the precise mechanical or other physical characteristics of the requirements, such as the torsional stiffness of the float gyroscope torsion bar, the stiffness coefficient of the flexible components, etc.. Precision machining is achieved under strictly controlled environmental conditions, using precision machine tools and precision gauges and gauges. Machining accuracy up to and beyond 0.1 micron is called ultra-precision machining. In the aerospace industry, precision machining is mainly used to process precision mechanical parts in aircraft control equipment, such as precision mating parts in hydraulic and pneumatic servo mechanisms, gyroscope frames and housings, air and liquid float bearing assemblies and floats, etc. The structure of precision parts of aircraft is complex, small stiffness, high precision required, and the proportion of difficult to machine materials is large.

Cause of stainless steel wrinkling: When the metal flows inward through the stretch ring in a radial manner, the compression force generated may cause wrinkles, and the fixture will prevent such wrinkles. If the metal flow is uneven or there is no support of the stretching ring, wrinkles will begin to occur. Thin materials need more fixing force than thick materials. How to control the fixing force during stainless steel stamping? The fixing force of stamping parts can be controlled in many ways. First, use a flat surface fixing pad. When metal flows under the fixing pad, the pressure will increase. If the fixing pad is designed at a slight angle, the fixing force will increase. In this way, the stamping will be more regular, but the stamping parts outside the stretch ring may wrinkle. If the flange will be cut in the future, you can not worry about this problem. The purpose of this design is to effectively control the metal flow into the stretching ring. Second, a punch ball can be added to the fixed pad, and a corresponding groove can be added below to further prevent the metal from flowing inward. The above measures are taken to make the side wall wait for more tension when necessary. Although there are ready-made parameters for reference of the fixed force, it is usually necessary to obtain the correct fixed force through repeated tests.

Based on my years of practical work experience, the following specifications are summarized for these two common blanking methods: 1 CNC blanking operation standard 1.1 General regulations on the thickness of plates by numerical control blanking (1) Ordinary Q235 plates are generally 1mm, 1.2mm, 1.5mm and 2mm thick. (If there are large batches of special parts, the material thickness can be extended to 3mm, but the mold with corresponding specifications needs to be opened) (2) Due to the size limit of the worktable of TruPunch1000 equipment, the overall dimension of the CNC blanking plate must be less than 1100mm (W) * 2450mm (L) (3) When formulating the production process flow, the general rules for plates are as follows: iron plates and aluminum plates that meet the above conditions should be digitally punched as much as possible, and stainless steel plates should not be digitally punched even if they meet the above requirements (due to the molding characteristics of stainless steel, the requirements for molds are very high). 1.2 General provisions of CNC blanking on workpiece profile (1) The shape shall not have an arc greater than R5, and the open angle shall be 45 ° and 90 °; (2) The process that must be completed by CNC punching: shutter, rolling rib, punching rib, rolling rib, punching convex tapping hole. (Corresponding molds are generally required) 1.3 General provisions for the contour of workpieces that cannot be CNC blanking （1） Φ Round hole, hexagonal hole and special shaped hole below 15 (2) Waist hole less than 5mm. 1.4 Notes for drawing of digital punch NC blanking has a certain impact on the front and back of the plate, which determines the aesthetics of the product. If the drawing conversion is not good, there will be burrs on the front, which will seriously affect the appearance and extend the grinding time. Digital blanking requires that the drawing is the front of the part, to avoid burrs on the front. If there are negative marks, they can be ignored. 2 Operation standard of laser cutting Laser cutting, no need to add additional mold, high processing accuracy. However, the energy consumption is large and the unit labor cost is high. In order to reasonably use the laser cutting machine and improve its service life, the following operation standards are established: 2.1 Cutting capacity (1) Iron plate thickness ≤ 10mm (if it is necessary to cut 12mm-16mm plates, try cutting to determine) (2) Thickness of stainless steel plate ≤ 6mm (if it is necessary to cut 8mm to 12mm plates, try cutting to determine) (3) The thickness of aluminum plate to be cut shall be ≤ 8mm (if it is necessary to cut 10mm to 16mm plates, it shall be determined by trial cutting) (4) Boundary dimension of cutting plate ≤ 2000mm * 4000mm (5) Requirements for cutting aperture: one 2.2 Some points for attention during laser cutting (1) Whether to use laser cutting depends on the economic value of different customers' products. For products with high economic value, more attention should be paid to laser cutting, otherwise less attention should be paid. (2) Consider whether laser cutting is applied according to the shape characteristics and quantity of the expanded drawing. Products with simple appearance shall not be cut by laser as far as possible; For products with large batch and single variety, laser cutting is not required. (3) For workpieces with complex shapes, laser cutting is considered. (4) For the parts that must be combined with laser and digital punch, the safety distance between the clamp and the punch shall be considered (the safety distance is 100mm), and the distance from the part edge to the hole edge shall be less than the safety distance, so as to ensure that the distance from the part edge to the hole edge is more than 100mm. Programmers need to consider the allowance, and pay attention to cutting after several strokes. twenty-two 2.3 Requirements for unfolding drawing for laser cutting (1) The laser mark is on the front of the drawing. (2) The tread plate must be placed on the reverse side. 2.4 Special process of laser cutting 2.4.1 Knock out hole It is convenient for customers to knock down easily, and the other surfaces are not deformed (unless the customer has specific requirements). The knock down hole is reserved for connection of 2mm, which cannot be too large; The number of reserved connection points shall be determined according to the size of knockout holes; 2.4.2 Laser marking line In order to facilitate bending and welding positioning by bending workers, manual scribing by workers is reduced and improved. For product accuracy and production efficiency, technicians should strengthen the use of laser marking. The following specifications are formulated for reference on what conditions and how to add stamps. (1) Laser marking of welding nails and drilling and tapping: the welding nails must be positioned with a circle and a cross line. The length of the cross line is 3mm * 3mm, and the circle size is the outer diameter of the boss at the bottom of the welding nails; thirty-three (2) Counterbore: the contour of the counterbore shall be marked with a laser marking line, which is convenient for the operator to process in place at one time; (3) Drilling: the hole diameter smaller than the plate thickness shall be positioned with cross lines, and the length of laser line marking line shall be 3mm * 3mm; (4) Bending line laser positioning line: it is determined according to the throat depth of the bending machine. When the bending size is larger than the throat depth or the bending sideline is in a deformed state and it is difficult to lean against the stop, it is considered to add a laser marking line. The length of the laser marking line is generally 20~50mm, which is convenient for the bending operator to identify; Under special circumstances, consider slotting when the reverse side needs to be bent, and the laser slotting incision is generally 0.5-2mm long; (5) Rolling circle achieved by bending method: it is required to mark the line from the starting point to the end point of the rolling circle, with a length of 10-20mm, and the middle part is evenly marked every 8-10mm, except for those with a special mold or being rolled by the rolling machine (R85 arc is pressed out by a special mold, but the starting point needs to be marked); (6) The side line is very small or irregular: when the stop cannot be used for measurement, the laser marking line shall be engraved; (7) Perforation positioning: when the front side needs to be marked and the reverse side still needs to be positioned, perforation positioning is required at this time; (8) Positioning of welding parts: the arc and special-shaped parts that are difficult to measure shall be positioned by laser marking during welding.

Common polishing methods include mechanical polishing, chemical polishing and electrochemical polishing, each of which has its own advantages and disadvantages. The specific choice depends on the structure and size of stainless steel products and product performance requirements. 1. Mechanical stainless steel polishing. The utility model has the advantages of good flatness and high brightness of the processed parts. Its disadvantages are high labor intensity, serious pollution, and the complex parts can not be processed, and its luster is not consistent, the luster is not kept for long, and it is dull and rusty. It is suitable for processing simple parts, medium and small products. 2. Chemical stainless steel polishing. Its advantages are less investment in processing equipment, complex parts can be thrown, fast speed, high efficiency and good corrosion resistance. Its disadvantages are poor brightness, gas overflow, need of ventilation equipment, and difficult heating. It is suitable for processing small batches of complex parts and products with low brightness requirements for small parts. 3. Electrochemical stainless steel polishing The utility model has the advantages of long mirror luster, stable process, less pollution, low cost and good corrosion resistance. Its disadvantages are high pollution prevention, large one-time investment in processing equipment, tooling and auxiliary electrodes for complex parts, and cooling facilities for mass production. It is suitable for mass production and mainly used for high-end products, Export products, tolerance products, their processing technology is stable, simple operation.

If the material used is austenitic stainless steel, it is nonmagnetic, but after cold working, a small amount of austenite will be transformed into martensite, so it will produce weak magnetism, but not very strong magnetism If non-magnetic requirements are high, it is recommended to replace non-magnetic stainless steel. After stainless steel stamping, how to do it without magnetism? There are many kinds of stainless steel, which can be divided into several categories according to the structure at room temperature: 1. Austenitic type: such as 304, 321, 316, 310, 303, 305, 307, 302, etc; 2. Martensite or ferrite: such as 430, 420, 410, etc; Austenite is nonmagnetic or weakly magnetic, while martensite or ferrite is magnetic. In order to completely eliminate the magnetism of 304 steel caused by the above reasons, high temperature solution treatment can be used to restore the stable austenite structure, so as to eliminate the magnetism. Material used: 304M is slightly magnetic after cold working (about 1.6u-2.0u); 304HC magnetism is (about 1.01u-1.6u); The magnetism of 316 material after cold working is less than 1.01u. All materials have good ductility and are easy to be cold formed. The tensile strength and yield strength can meet the requirements. As long as you select the product correctly according to the actual use requirements, I believe it can meet your needs. After cold working, the magnetism of each material is 316

There are certain technical difficulties in machining trapezoidal threads on CNC lathes, especially in high-speed cutting. It is not easy to observe and control during machining, and the safety and reliability are also poor. This requires correct tool geometry and processing technology. An efficient and feasible processing method is introduced. Whether on an ordinary lathe or on a CNC lathe, there is always a great technical difficulty in processing trapezoidal threads for students in secondary and higher vocational schools, especially in the high-speed turning of trapezoidal threads on a CNC lathe. Most books and textbooks do not introduce special topics. It is difficult for students to master their fine calculation and reasonable processing technology. The author will focus on the high-speed turning method of trapezoidal thread according to the examination questions of senior workers in Hunan Province in recent years and in combination with his own experience and experience. 1、 Selection of processing methods As shown in Figure 1, when machining trapezoidal threads on the CNC lathe, the three jaw chuck adopts the method of one clamp and one top. For the convenience of tool setting and programming, the program origin is set at the center point of the right end face of the workpiece. In addition, a tool setting template is also made to facilitate the accuracy of the Z direction when changing tools in rough and fine turning. It should be pointed out that because of the high-speed machining of trapezoidal threads, cemented carbide tools are selected. When turning trapezoidal thread at high speed, due to the excessive thread pitch, in order to prevent "knife pricking" and "blade breakage", it is required that the cutting force should not be too large when machining trapezoidal thread, and the tool should not cut on three sides at the same time. Through years of practice, the author has proved that the straight cutting method or straight grooving method can not be used for processing with thread cutting commands G32 and G92 on the economic NC lathe. Even though the method of using G92 combined with the left and right swing of subprogram introduced in many magazines in recent years is not the best method for layered cutting. Although this method theoretically can reduce the force during cutting, it ignores that most of our commonly used lathes are economic NC lathes, However, the control system of economical CNC lathe is semi closed loop, so that the servo system can not keep up with the numerical requirements of the CNC system when swinging left and right, thus changing the machining pitch. Considering the comprehensive programming and processing, combined with practical experience, I think it is a better, safe, reliable and easy method to use the thread cutting compound cycle command G76 to process.