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

1. Materials for shaft parts ① Shaft parts commonly used materials are 35, 45, 50 high-quality carbon structural steel, 45 steel is the most widely used, generally tempered, hardness of 230 to 260HBS. ② less important or less loaded shaft available Q255, Q275 and other carbon structural steel. ③ Shafts subject to higher forces and high strength requirements can be tempered with 40Cr steel with hardness of 230-240HBS or hardened to 35-42HRC. ④ If it is high-speed, heavy-duty conditions of the work of shaft parts, the choice of 20Cr, 20CrMnTi, 20Mn2B and other alloy structural steel or 38CrMoAIA senior quality alloy structural steel. These steels by carburizing quenching or nitriding treatment, not only high surface hardness, but also its heart strength is greatly improved, with better wear resistance, impact toughness and fatigue strength performance. ⑤ ductile iron, high-strength cast iron due to good casting performance, and vibration damping performance, commonly used in the manufacture of complex shape structure of the shaft. Especially our rare earth a magnesium ductile iron, impact toughness, but also has the advantages of friction absorption, low sensitivity to stress concentration, etc., has been used in automobiles, tractors, machine tools on the important shaft parts. (6) without the final heat treatment to obtain high hardness of the screw, generally available tensile strength of not less than 600MPa of 45 and 50 medium carbon steel. Precision machine tool screws can be made of carbon tool steel T10, T12. After the final heat treatment to obtain high hardness of the screw, with CrWMn or CrMn steel manufacturing, can ensure that the hardness of 50 ~ 56HRC. 2. Technical requirements for shaft parts ① Dimensional accuracy The dimensional accuracy of the main journal diameter is generally IT6~IT9, and the precision is IT5. For the step shaft, the length of each step is given tolerance according to the requirements of use, or the tolerance is assigned according to the requirements of the assembly size chain. ② Geometric accuracy Shafts are usually supported on bearings with two journals, which are the assembly reference of the shaft. The geometric accuracy (roundness, cylindricity)) of the support journal should generally be required. The general accuracy of the journal geometry shape tolerance, should be limited to the diameter tolerance range, that is, according to the inclusion requirements in the diameter tolerance after the mark E, such as higher requirements, and then marked its allowable tolerance value (that is, after the size tolerance note E outside, and then add a box to mark its shape tolerance value). ③ Mutual position accuracy Shaft parts with the journal (assembly transmission journals), relative to the support journal coaxiality is its mutual position accuracy of the general requirements. For the reason of convenient measurement, radial circular runout is commonly used to indicate. In addition, there are requirements for perpendicularity of axial positioning end face and axis center line, etc. ④ Surface roughness In general, the surface roughness of the support journal is Ra0.16 ~ 0.63um, with the surface roughness of the journal is Ra0.63 ~ 2.5um. For general parts, typical parts, the above generally have the corresponding tables and information available.  

The main function of shaft parts is to support other rotating parts and transfer torque, but also through the bearings and machine frame connection, is composed of one of the important parts of the machine. Shaft parts are rotating parts, its length is greater than the diameter, usually by the outer cylindrical surface, conical surface, bore, thread and the corresponding end face composed of. Shafts often have splines, keyways, transverse holes, grooves, etc. According to the function and structural shape, there are various types of shafts, such as light shafts, hollow shafts, half shafts, stepped shafts, spline shafts, crankshafts, camshafts, etc., which play a supporting, guiding and isolating role. Translated with www.DeepL.com/Translator (free version) 1. View expression (1) shaft parts are mainly rotating body, generally in the lathe, grinder processing, commonly used a basic view expression, the axis is placed horizontally, and will be placed on the right side of the small head, easy to see the map when processing. (2) in the shaft of the single keyway is best to draw the full shape towards the front. (3) For the structure of the hole and keyway on the shaft, it is usually expressed in a partial section view or profile view. In addition to clearly expressing the shape of the structure, the removed section in the section drawing can also conveniently mark the dimensional and form tolerances of the structure. (4) The small structures such as receding grooves and rounded corners are expressed by local enlargement. 2. Dimensioning (1)The main datum in the length direction is the main end face of the installation (shaft shoulder). The two ends of the shaft are generally used as the measurement reference, and the axis is generally used as the radial reference. (2) The main dimensions should be noted first, and the remaining multi-segment length dimensions are noted in the order of turning and machining. Most of the local structures on the shaft are positioned close to the shaft shoulder. (3) In order to make the marked dimensions clear, easy to see the diagram, it is appropriate to separate the internal and external dimensions on the section view, the dimensions of different processes such as turning, milling, drilling, etc. are marked separately. (4) For the shaft chamfering, chamfering, receding groove, grinding wheel overrun groove, keyway, center hole and other structures, the dimensions should be marked after consulting the relevant technical data.    

Large scale machining is divided into processing stages. The surfaces with high processing quality requirements are divided into processing stages, which can be effectively divided into three stages: rough processing, semi finish processing and finish processing. Mainly for processing quality; It is conducive to the rational use of equipment, the arrangement of heat treatment procedures, and the detection of blank defects. First processing datum: during the processing of parts, the surface used as the positioning datum should be processed first, so as to provide a precise datum for subsequent processing as soon as possible. It is called "benchmark first". For large-scale machined parts such as box, bracket and connecting rod, the plane shall be machined first and then the hole shall be machined. In this way, the holes can be machined by plane positioning, the position accuracy of the plane and the holes is improved, and the machining of the holes on the plane is convenient. The finishing of main surfaces (such as grinding, honing, fine grinding rolling, etc.) should be carried out at the stage of the process route. The surface finish after processing should be above ra0.8um. Any slight collision will damage the surface. After finishing, it should be protected with flannelette. Hands or other objects are not allowed to directly contact the workpiece, so as to avoid damage to the finished surface due to transfer and installation between processes. How to remove burrs in large-scale machining? 1. The traditional way of manual deburring is steel file, sandpaper and grinding head; The trimming knife gradually replaces these traditional methods, which is simple and convenient to use, does not require technical treatment, saves cost and is environmentally friendly. 2. Chemical deburring is the automatic and selective deburring of parts made of metal materials based on the principle of electrochemical reaction. It can be widely used for deburring of pump body, valve body, connecting rod, plunger needle valve couple and other parts made of different metal materials in pneumatic, hydraulic, construction machinery, nozzle oil pump, automobile, engine and other industries. It is applicable to internal burrs that are difficult to remove, parts after heat treatment and finished machining. 3. Electrolytic deburring is suitable for deburring hidden parts, cross holes or complex shaped parts, with high production efficiency. Deburring time generally only takes a few seconds to tens of seconds. This method is often used for deburring gears, splines, connecting rods, valve bodies and crankshaft oil passage orifices, as well as sharp corner rounding. The disadvantage is that the vicinity of the burr of the part is also affected by electrolysis, and the original luster of the surface will be lost, and even the dimensional accuracy will be affected.

When machining a workpiece in a machining plant, in order to obtain a relatively high precision of the machined workpiece, it is necessary to select the right tool to cut the workpiece. There are many main factors that should be considered in the selection of tools. The first is the material and performance of the workpiece to be processed, such as whether the material is metal or non-metal, and the hardness, stiffness, plasticity, toughness and wear resistance of the machined material. The next thing to be considered is the processing technology category formulated by the machining plant. When machining parts, select CNC turning, drilling, CNC milling, boring or rough machining, semi finishing, finishing and ultra finishing, and determine the appropriate tools according to the processing technology. There is also information about machining workpieces, the cutting amount that the tool can bear and various auxiliary factors. The geometric shape of the workpiece, the machining allowance, the technical requirements and economic indicators of the parts. The cutting parameters of the tool mainly include three factors, including spindle speed, cutting speed and cutting depth; Auxiliary factors, including operation interruption time, vibration frequency, power fluctuation or sudden interruption, also need to be considered. In the machining process of a machining plant, the accuracy of the position of the machined surface on other surfaces mainly depends on the clamping of the workpiece. Direct alignment and clamping is a clamping method that directly aligns the position of machined workpiece on the machine tool with dial indicator, marking plate or visual inspection. Marking, alignment and clamping is to mark out the center line, symmetry line and machining line of each surface to be machined on the blank according to the part drawing, then mount the workpiece on the machine tool, and align the clamping position of the workpiece on the machine tool according to the marked line. This clamping method has low productivity, low accuracy, and high requirements for workers' technical level. It is generally used to process complex and heavy parts in single piece and small batch production, or where the dimensional tolerance of the blank is too large to be clamped directly with a clamp. Clamping with clamps is specially designed according to the requirements of the process to be processed. The positioning elements on the clamps can make the workpiece quickly occupy the correct position relative to the machine tool and the cutter, and the clamping and positioning accuracy of the workpiece can be improved without alignment. The production rate of clamping with clamps is high and the positioning accuracy is high, but special clamps need to be designed and manufactured, which are widely used in mechanical processing plants for batch and mass production.

In the process of machining precision mechanical parts, turning and milling are the common machining methods, and some common precision parts are milling or turning parts. After rough cutting of the workpiece, the whole workpiece is actually very close to the appearance and size required by the workpiece itself, but at this time, there is still a large margin on the workpiece surface for fine cutting. The surface of the workpiece after fine cutting is smoother and the size will be more accurate. In general, the workpiece processed by precision machinery parts can reach the required appearance and size of the workpiece after one rough cutting and one fine cutting. However, not all workpieces need only one cut, and some parts of some workpieces may need to be rough cut many times. At the same time, there are also some workpieces whose accuracy requirements are not too high or whose cutting amount is very small, which may only require one finishing cut to meet the requirements of the workpiece. The rough cutting in the processing of precision mechanical parts requires a larger cutting force than the fine cutting because the workpiece needs a larger cutting allowance. This requires that the machine, the cutter and the workpiece can meet. Moreover, the rough cutting can quickly remove the allowance, and the surface performance after the effect can not be too rough. The precision cutting of precision mechanical parts processing is to meet the requirements of the workpiece in terms of surface performance and dimensional accuracy. Therefore, the tools used for precision cutting also need to be very sharp. Because of the small cutting amount, the measurement precision is required to be very high. In fact, there are many parts that we can't see that have an inseparable relationship with the processing of precision mechanical parts, such as the very small nuts in mobile phones. Because these nuts are actually customized according to the needs of mobile phone manufacturers, there are few standards, and the accuracy requirements are very high, almost all of them depend on precision mechanical processing.

The machining factory emphasizes that the machining should meet certain precision, which means that the main parameters of the actual geometry of the steel parts after machining are consistent with the idealized values required by the part drawings. And the inconsistent level among them is called production and processing deviation. The production and processing precision of the machining plant includes three levels: one is the specification precision, which limits the specification deviation between the two standards of the production and processing surface layer to not exceed the necessary scope; On the other hand, the geometric shape precision limits the macroeconomic geometric shape deviation of the production and processing surface, such as roundness, cylindricity, parallelism and straightness. On the other hand, it is the precision of mutual parts, which limits the deviation of mutual parts between the standards of the surface produced and processed by the machining plant, such as the axial degree, flatness and parallelism. The precision of production and processing is the conformity between the actual specifications, shapes, positions and main parameters of several geometric figures on the surface of parts and components after production and processing and the main parameters of idealized geometric figures specified in the engineering drawings. The main parameters of the idealized geometric figure, in terms of specifications, mean specifications; For the surface geometry, it refers to circles, cylinders, plans, spheres and parallel lines; For the mutual parts in the middle of the surface layer, it means parallel plane, vertical, coaxial output, symmetry, etc. The deviation between the main parameters of the geometric figure and the main parameters of the idealized geometric figure of the parts produced by the machining plant is called the production and processing deviation. Production and processing precision and production and processing deviation are professional terms for commenting on the main parameters of the surface geometry of production and processing. The precision of production and processing is considered by the tolerance grade. The smaller the grade value, the higher the precision; The production and processing deviation is expressed by the standard value. The larger the standard value, the larger the deviation.

Precision machinery parts processing is one of the main keywords of the website, so it needs to be familiar with and understood. So the following is to elaborate and explain its relevant knowledge, so that we can have learning objects and content, and then know how to correctly process precision machinery parts, without various problems in the process. 1. Are there many aspects to be considered in the purchase of finished products processed by precision mechanical parts? For the finished products processed by precision mechanical parts, many aspects should be taken into consideration when purchasing them. Therefore, it is certain that the answer to this question is yes. Moreover, we need to know what aspects should be taken into account, and there should be no omission, so as not to affect the correct purchase of the product. In addition, this is also a basic requirement that must be met without any carelessness or slackness. 2. In the processing of precision mechanical parts, are there many processing objects and available processing equipment? In the processing of precision mechanical parts, there are many processing objects and available processing equipment, so we can know that the answer to this question is yes. In terms of processing objects, there are boxes, bases, spindles, flanges and sheet metal. The processing equipment that can be used is lathes, milling machines, planers and grinders. 3. Are there any requirements for the size of precision mechanical parts processing? For the processing of precision mechanical parts, there are some specific requirements in terms of size, and it is necessary to know these specific requirements, so as to avoid some problems in this respect. In terms of specific requirements, there are cylindrical proportion requirements and the specified range of positive and negative errors, which are very important and indispensable. 4. Is the operator's operation important when processing precision mechanical parts? For the processing of precision mechanical parts, the operation of its operators is very important, and it is an important aspect that can not be underestimated and treated carelessly, because this aspect relates to the quality of finished products and the use performance of finished products, so the above conclusion can be reached. In addition, its operators should master some professional knowledge and operation skills, so as to avoid wrong operation.

  The use of machining centers is a complex technical project of a certain scale. It involves a series of work such as production management, technical management and personnel training. All the work should follow a certain principle of operation. This principle is the guarantee system to give full play to the benefits of the machining center. Therefore, pay attention to the use of technology is one hand, pay attention to the management of technology is essential on the other hand.   The domestic production plants have taken the machining center as a high-efficiency automation equipment, as the key equipment. However, the management of the equipment is uneven. In the management of the machining center, must advocate the production characteristics of the machining center and it needs to cooperate with the production beat of each link. Can not move the management of ordinary machine tools to CNC machine tools, in the management of the following points should be noted.   1. give full play to all the functions of the machine tool, when the machine is put into use, in order to give full play to all the functions of the machine tool, should have to carefully read the manual, a deep understanding of the various functions of the machine tool and its capabilities. According to the nature of the plant processing parts, reasonable arrangements for processing objects, processes, select the appropriate supporting parts and accessories. Prepare spare parts for wearable parts.   2. set CNC department, CNC machine tools in a special department, process technology preparation, production management preparation by the factory technology department unified. Production workshop with special technical personnel. Avoid single CNC machine tools scattered in each workshop, only processing a small number of key parts, resulting in a large number of production time idle situation. Set up a special section to facilitate the management of maintenance.   3. Reasonable arrangement of production beats, technical preparation cycle, in the arrangement of production tasks to the machining center, the process department should first process documents, processing procedures, tool cards are ready, and then send the processed parts to the processing position. In order to avoid the operator to stop to find tools, modify the program, assembly fixture and cause a long downtime.   4. Select the appropriate rules and regulations, such as CNC machine tool management system, safety operating procedures, CNC machine tool use regulations, CNC machine tool maintenance, point inspection system, etc.. At the same time, to the manufacturing and design departments to provide timely feedback.   5. Pay attention to the construction of technical teams on a complex equipment, including a variety of technical achievements, fully grasp the use of a well-trained technical team, including technology, operation, mechanical and electrical maintenance, etc., the training of personnel to have a process, leading the management of equipment departments to have a comprehensive understanding of this.

  In the CNC machine tools, especially in the machining center processing parts, the process is very complex, many parts only in a loading card to complete the entire process. But the rough machining of parts, especially forging blank parts of the reference surface, positioning surface and other parts of the processing, should be processed on ordinary machine tools to complete, in the card to CNC machine tools for processing. This can play the characteristics of CNC machine tools, maintain the accuracy of CNC machine tools, extend the service life of CNC machine tools, reduce the cost of using CNC machine tools. After rough machining or semi-finishing parts mounted on CNC machine tools, CNC machine tools in accordance with the prescribed procedures step by step for semi-finishing and finishing.   The choice of machining workpiece   Different types of parts should be machined on different types of CNC machines. CNC lathe is suitable for processing the more complex shape of shaft parts and complex curved rotary formation of the mold cavity. CNC vertical boring and milling machine and vertical machining center are suitable for processing box, box cover, plane cam, sample plate, complex shape of plane or three-dimensional parts, as well as the internal and external cavities of the mold. CNC horizontal boring and milling machines and horizontal machining centers are used to process various complex curves, curved surfaces, impellers, molds, etc. In short, different types of parts to use different CNC machine tools for processing.   1, the process division method for processing parts on CNC machine tools are.   ① tool concentration division method The method is to divide the process according to the tool used, with the same knife to complete all the parts can be completed on the part. Then use the second tool, the third tool to complete the parts they can complete. This can reduce the number of tool changes, compress the empty travel time and reduce unnecessary positioning errors.   ② Roughing and finishing sequencing method For a single part, roughing and semi-finishing should be done first, and then finishing. For a batch of parts, first all rough machining, semi-finishing machining, and finally finishing machining. Between roughing and finishing, it is best to be separated by a period of time, so that the deformation of the parts after roughing is fully recovered, and then finish machining, in order to improve the machining accuracy of the parts.   ③ according to the processing part of the sequence method General first processing plane, positioning surface, after processing holes; first processing simple geometry, and then processing complex geometry; first processing lower precision parts, and then processing higher precision requirements of the parts. In short, in the CNC machine tool processing parts, the division of the processing process according to the specific circumstances of the parts specific analysis. Many processes are arranged in accordance with the above-mentioned comprehensive arrangement of the sub-order method.   2, the workpiece loading card mode In the CNC machine tool processing parts, because the process is concentrated, often in a card to complete all the processes. Therefore, the positioning of the parts, clamping method to pay full attention to the following issues.   ① Try to use a combination of fixtures. When the workpiece batch is larger, the workpiece accuracy requirements are higher, you can design a special fixture.   ② Parts positioning, clamping parts should be considered not to hinder the processing of various parts, tool replacement and measurement of important parts, especially to pay attention to not occur tool and workpiece, tool and fixture collision phenomenon occurs.   ③ Clamping force should strive to pass through (or close to) the main support points or within the triangle formed by the support points; should strive to be close to the cutting part and in a place of better rigidity. Try not to be above the diameter of the hole being machined to reduce the deformation of the part.   ④ Parts of the card, positioning to take into account the consistency of repeated installation, in order to reduce tooling time, improve the consistency of the same batch of parts processing. Generally the same batch of parts using the same positioning benchmark, the same mounting method.   3, the processing route to determine   Machining route refers to the trajectory and direction of tool movement during the machining process of CNC machine tools. The determination of each process machining route is very important, because it affects the machining accuracy and surface roughness of the parts. The following points should be considered in the determination of the machining route.   ① Minimize tool-in and tool-out times and other auxiliary times.   ② When milling the contour of the part, try to use the smooth milling processing method to reduce the machine chatter, improve the surface roughness of the part and machining accuracy.   ③ choose a reasonable feed and retreat position, try to avoid normal cutting along the part contour and feed stop in the middle. Feed and retreat position should be selected in the unimportant position.   ④ The machining route is generally to machine the outer contour first and then the inner contour.

China's CNC precision machining factory in the field of patents has always attached more importance, take the field of seal manufacturing, CNC machining factory has more patents or 2010-2019, China's CNC machining seal manufacturing industry, the number of patent applications climbed year by year, jumped from 2735 to 6810. Into 2020, the development of CNC precision machining industry tends to be stable, the number of patent applications in the field of CNC machining seal manufacturing slowly declined. 2020, China's CNC precision mechanical parts machining seal manufacturing industry patent applications reached 6508 pieces. And as of 2021, the number of patent applications in China's CNC precision mechanical parts machining seal manufacturing industry is only 3727. Although China's CNC precision machining seals manufacturing industry has made greater progress, but far from meeting the development of other CNC precision machining industry for various types of sealing products standardized, serialized products, especially compared with the international advanced countries CNC precision machining, China's CNC precision parts machining seals products, whether in product quality, or in product varieties, there is a considerable The gap. In addition, China's CNC precision machining seals manufacturing industry, the overall competitiveness of enterprises is weak. Although China's CNC precision parts machining seals manufacturing industry is developing at a faster pace, but the strength of CNC machining seals is very slow. In the early 80s, only in Jiang, Zhejiang, Lu there are a few such CNC machining factory, in the present and both coastal, mainland, or the South, North, everywhere you can see seals CNC precision machining factory, the entire CNC precision machining sealing industry has been a few from the previous, the development of more than 900, the development rate is still relatively fast.