Monthly Archive March 31, 2021

Precision CNC machining of mass parts

It is very simple to use the tool magazine for the cost of the CNC system, but the spindle and tool magazine, air compressor and various tool handles will increase the cost, and the programming and adjustment of the tool magazine will also take the corresponding time. Therefore, for the production of less than one or two hundred workpieces of the same variety, the machining center should not be used as far as possible, with high cost and low efficiency.

Precision CNC machining can use the automatic tool setting system, a tool up, a button, machine tool automatic tool setting, direct processing, error within 0.001 ~. 0003mm, compared with the automatic change time, not much slower. If it is a machining center, but there is no automatic tool setting device, the efficiency of the latter is much higher than that of the former.

For the domestic manufacturing industry, especially the mold production enterprises, generally single piece production, and sufficient labor resources, therefore, for the processing of small batch of industrial parts, we should fully consider the use value of funds, do not easily use the processing center equipment.

  1. Precision CNC has high machining precision and high machining quality;
  2. CNC machining can carry out multi coordinate linkage, and can process complex parts;
  3. When the CNC machine tool changes the parts, it only needs to change the NC program, which can save the production preparation time;
  4. CNC lathe processing itself has high precision and high rigidity. It can choose favorable processing amount and high productivity (generally 3 ~ 5 times of ordinary machine tools);
  5. CNC lathe has a high degree of automation, which can reduce the labor intensity;
  6. CNC lathe processing mass production, product quality is easy to control;

CNC lathe processing disadvantages:

  1. CNC lathe processing requires lower quality of operators and higher technical requirements of maintenance personnel.
  2. CNC machine tool processing route is not easy to control, not as intuitive as ordinary machine tools.
  3. The maintenance of lathe is inconvenient and the technical requirements are high;
  4. CNC lathe processing technology is not easy to control.

Introduction of CNC milling machine

The biggest difference between CNC milling machine and machining center is that the machining center has the ability to exchange machining tools automatically. By installing different tools on the tool magazine, the machining tools on the spindle can be changed through the automatic tool changing device in one clamping, and a variety of machining functions can be realized.

CNC machining center is composed of mechanical equipment and CNC system, which is suitable for processing complex parts. CNC machining center is one of the most widely used CNC machine tools with the highest output in the world. Its comprehensive processing ability is strong, the workpiece can complete more processing content after clamping at one time, and the processing accuracy is high. For the batch workpiece with medium processing difficulty, its efficiency is 5-10 times higher than that of ordinary equipment, especially it can complete the processing that many ordinary equipment can’t complete, and it is more suitable for single piece processing with complex shape and high precision requirements or small and medium batch multi variety production. It concentrates the functions of milling, boring, drilling, tapping and cutting threads on one equipment, so that it has a variety of technological means. Machining centers are classified into horizontal and vertical machining centers according to the spatial position of the spindle. According to the classification of process uses: boring and milling machining center, composite machining center. According to the special functions, there are single table, double table and multi table machining centers. Machining center of single axle, double axle, three axle and changeable headstock.

Introduction of computer gong finishing

The feed route of finishing machining is basically carried out along the contour of the parts. Therefore, the key point of determining the feed route is to determine the feed route of rough machining and empty stroke. In the CNC lathe processing, the determination of the processing route should generally follow the following principles.

① It should be able to ensure the accuracy and surface roughness of the workpiece to be processed.

② The processing route is shortest, the idle travel time is reduced, and the processing efficiency is improved.

③ The workload of numerical calculation should be simplified as much as possible.

④ For some repeated programs, subroutines should be used.

Advantages and disadvantages of CNC CNC CNC machining has the following advantages:

① The number of tooling is greatly reduced, and complex tooling is not needed to process complex parts. If we want to change the shape and size of the parts, we only need to modify the processing program of the parts, which is suitable for the development and modification of new products.

② The machining quality is stable, the machining accuracy is high, and the repetition accuracy is high, which can meet the machining requirements of aircraft.

③ In the case of multi variety and small batch production, the production efficiency is high, which can reduce the time of production preparation, machine adjustment and process inspection, and reduce the cutting time due to the use of the best cutting quantity.

④ It can process complex surface which is difficult to be processed by conventional methods, and even process some parts which cannot be observed.

Application of coordinate measuring instrument

It is widely used in mechanical manufacturing, electronics, automotive and aerospace industries. It can detect the size, shape and mutual position of parts and components, such as box, guide rail, turbine and blade, cylinder block, cam, gear shape and other space surface measurement. In addition, it can also be used for scribing, centering hole, photolithography integrated circuit, etc., and can scan continuous curved surface and prepare machining program of CNC machine tool. Because of its versatility, wide measurement range, high precision, high efficiency, good performance, and can be connected with flexible manufacturing system, it has become a kind of large precision instrument.

With the development of CMM market, CMM, as a modern large-scale precision instrument, has shown its importance and broad development prospects. It can measure the three-dimensional dimension of space conveniently and realize on-line detection and automatic measurement.

Its advantages are as follows:

  1. It has strong versatility, can realize the measurement of spatial coordinates, and can easily measure the three-dimensional outline size and position accuracy of various parts;
  2. The measurement is accurate and reliable
  3. It is convenient for data processing and program control. Therefore, it can be incorporated into automatic production and flexible processing line, and become an important part. At present, CMM is developing rapidly at home and abroad. Famous foreign manufacturers include Zeiss and Leitz of Germany, DEA of Italy, Brown & Sharpe of America, Mitutoyo of Japan, etc. With the development of various industries, the development of coordinate measuring instruments will also be rapid.

CNC computer gong debugging method

CNC computer gong processing machine precision and function debugging method:

  1. Using precision level instrument and other testing tools, the main bed level of the computer gong processing machine tool is precisely adjusted by adjusting the pad iron, so that the geometric accuracy of the machine tool can reach the allowable tolerance range;
  2. For the automatic tool changing device, adjust the position of tool magazine, manipulator, stroke parameters, etc., and then check the action with instructions to ensure accuracy;
  3. For the machine tool with APC automatic exchange table, after adjusting the relative position, carry out automatic exchange;
  4. After the adjustment of the machine tool, carefully check whether the parameter setting values in the numerical control system and the programmable controller conform to the data specified in the random index, and then test the main operation functions, safety measures, and the execution of common instructions.
  5. Check the auxiliary functions and accessories of the machine. CNC computer gong NC machining is the basis of modern manufacturing technology, this invention for the manufacturing industry, has epoch-making significance and far-reaching influence.

CNC machining center milling cutter

CNC machining center used on the milling cutter, should choose all cemented carbide, general milling machine used on the selection of white steel material. The hardness of white steel milling cutter is softer than that of cemented carbide milling cutter. Cemented carbide milling cutter has good thermal hardness, wear resistance, but poor impact resistance. The carbide is made by powder metallurgy. Its hardness can reach about 90hra and its thermal property can reach about 900-1000 degrees.

  1. Number of milling cutter teeth

When selecting a milling cutter, the number of teeth should be considered. For example, the coarse tooth milling cutter with a diameter of 100 mm only needs 6 teeth, while the dense tooth milling cutter with a diameter of 100 mm can have 8 teeth. The size of pitch will determine the number of cutter teeth to be cut together in milling, which affects the smoothness of cutting and the requirement of cutting rate.

  1. Chip holding tank

Coarse tooth milling cutter is mostly used for rough machining, because it has a large chip holding groove. Assuming that the chip holding groove is not large enough, it will make it difficult to roll the chip or the conflict between the chip and the tool body or workpiece aggravate. At the same feed rate, the cutting load of coarse tooth milling cutter is larger than that of dense tooth milling cutter.

  1. Cutting depth

In finish milling, the cutting depth is shallow, generally 0.25-0.64mm. The cutting load of each tooth is small (about 0.05-0.15mm), and the power required is small. It is able to select dense tooth milling cutter, and it is able to select larger feed rate.

  1. Application of rough milling

In heavy load rough milling, excessive cutting force can make the machine tool with poor rigidity vibrate. This kind of chatter will lead to the edge collapse of cemented carbide blade, and then shorten the tool life. Selecting coarse tooth milling cutter can reduce the requirement of machine power.

CNC machining center workpiece processing process is no longer like the traditional processing equipment, the need for uninterrupted control of the machine tool to end, control the function parts of the machine tool for messy and precise action, and then high-precision, efficient end of the processing process. The programming of workpiece processing is the key of workpiece processing in machining center. However, if the programming is not reasonable or the parameters are not set properly, the machining accuracy and power of the workpiece will be seriously affected, such as overcutting. Overcutting is a serious problem in workpiece processing, which can lead to the invalidation of workpiece. For some reason, the front-line processing personnel have worked out the processing program which is sure to be overcut. If the system can announce the alarm signal in advance in the working process, the overcut can be avoided.

CNC machining center cutting oil

It often causes oil leakage in CNC machining center. There are three main problems in oil change. First, for the parts with high viscosity lubricating oil, it will affect the sealing performance of the corresponding box, shaft hole and other parts, and sometimes greatly reduce the sealing performance of these parts. Second, if the oil tank is not cleaned when changing oil, the dirt in the oil tank may enter into the lubrication system, block the oil circuit and wear the seals, causing oil leakage. Third, when changing the oil, the amount of oil is too much, especially in the parts with rotating parts, because of the stirring effect of rotating parts, it is more prone to oil spill.

Improper selection and adjustment of lubrication system parts cause oil leakage.

For example, when CNC machining and maintenance personnel select the oil pump with too high pressure or too large oil output, or when adjusting the system pressure, the pressure of relief valve, safety valve and pressure reducing valve is too high, and the flow of CNC machine tool lubrication system is too large, which does not match with the oil return system and sealing system, it will cause oil leakage.

In fact, it is not just the above points that cause the oil leakage of CNC machining center. If we encounter similar problems in operation, we must do a good job in checking and find out the reasons in time to avoid unnecessary losses. After the purchase of the machining center, do a comprehensive inspection to see if there are casting defects or parts damage, if any, contact the manufacturer in time. When operators use CNC machining center to process workpieces, they should also pay attention to the following points:

(1) For the first trial cutting process of CNC machining, the single-stage operation mode should be adopted.

(2) When the CNC milling machine starts to run automatically, the fast rate and feed rate s are in the lowest gear, and then the efficiency is improved after cutting into the workpiece.

(3) In the operation of NC milling machine, we need to pay attention to the coordinate display of CNC system.

CNC thread milling method

To be proficient in the operation of CNC machine tools, we should learn: system operation mode, fixture installation, part benchmark alignment, tool setting, zero offset setting, tool length compensation, radius compensation, tool and handle loading and unloading, tool grinding, part measurement (proficient in using vernier caliper, micrometer, dial indicator, dial indicator, inner diameter lever), etc .

Can reflect the level of an operator is: horizontal processing, and large gantry (moving beam, top beam) processing. Must have good fixture foundation and measurement technology level. The difficulty of fixture analysis is that it can only be qualitative, but it is difficult to be quantitative.

In the process of CNC machining, there is a method called thread milling. What is it? CNC thread milling is a milling method which uses thread milling cutter, machining center three-axis linkage, namely x, Y axis arc interpolation, Z axis linear feed.

Thread milling is mainly used for large hole thread and difficult to machine material thread hole. It has the following characteristics:

(1) high processing speed, high efficiency and high processing precision. The cutting tool is made of cemented carbide, and the cutting speed is fast. Therefore, the precision of thread milling tool is high.

(2) milling tools are widely used. As long as the pitch is the same, whether it is * * thread or right-hand thread, a tool can be used, which is conducive to reducing the cost of the tool.

(3) milling is easy to remove chips and cool, and the cutting condition is better than tap. It is especially suitable for thread machining of difficult to machine materials such as aluminum, copper and stainless steel,

Especially suitable for large parts and valuable material parts of the thread processing, to ensure the quality of thread processing and workpiece safety.

(4) because there is no tool front-end guide, it is suitable for processing blind holes with short thread bottom holes and holes without undercut.

The highest precision of computer gong processing

Machining center in the process of processing mold, the accuracy and surface processing quality requirements are higher and higher, in order to ensure the quality of mold processing, we should consider the selection of machine tool, tool handle, tool, processing scheme, program generation, operator requirements and other aspects.

  1. With the improvement of product design requirements and the development of high-speed and high-precision processing technology, the selection of high-precision and high-speed machining center has greatly improved the quality and speed of mold NC processing, reduced the processing procedures, shortened the production cycle and clamping times of mold, and sometimes eliminated the time-consuming fitter repair work. The high-speed and high-precision machining of mold has gradually become one of the important contents of the technological transformation of mold production enterprises. It is inevitable that the high-speed CNC machining center will replace the traditional low-speed machining, and the development of mold manufacturing technology will also bring us more rich product experience.
  2. The use of high-speed and high-precision machining center with suitable tool handle structure will also drive the update of relevant process equipment. In particular, the influence of cutting tools on NC machining quality and toolholder will become prominent. In the rotary tool processing system, the chuck is closely connected with the machine tool (or its combination) to ensure the realization of tool processing performance. Generally, there are HSK hollow toolholder and BT toolholder in the interface between machine tool and toolholder. The taper of taper shank interface between machine tool spindle and BT toolholder is 24:7, which is suitable for traditional low-speed machining. Because BT toolholder and machine tool spindle are only taper fit, the clearance of taper fit will increase under the action of high-speed centrifugal force, which affects the quality of NC machining. Generally, when the spindle speed exceeds 16000 rpm, we will need to use HSK hollow handle. The positioning structure of HSK arbor is over positioning, which provides a standard connection with the machine tool. Under the pulling force of the machine tool, the short cone and end face of the arbor are closely matched with the machine tool.
  3. Choosing the right cutting tools, the reasonable use and selection of cutting tools will be an important factor affecting the quality of NC machining. Cemented carbide tools are more and more widely used. In high speed machining, coated cemented carbide will replace most of the front steel tools, including reamer, ball head tool, boring tool and other simple tools. Coated cemented carbide will play an important role in high speed machining tool materials and be applied to most of the conventional processing fields. Generally, we know that in rough machining, we will use large diameter tools for processing. In order to save cost and reduce the difficulty of tool manufacturing, we will use machine clip cemented carbide blade In the semi finish machining, the insert tool with high speed and high feed is used to make the semi finish machining move faster; in the finish machining, the high-precision round head mirror blade is used to ensure the strength of the tool and the tool holder, which can save the expensive cost of selecting the whole alloy tool while maintaining the machining accuracy. In the process of machining, we also need to pay attention to the inner contour fillet radius of the finishing parts must be greater than or equal to the radius of the tool, select the tool whose radius is less than the radius of the corner fillet to process in the way of arc interpolation or diagonal interpolation, so as to avoid the phenomenon of overcutting caused by linear interpolation and ensure the quality of mold finishing.
  4. The importance of NC process design in high-speed and high-precision machining is raised to a higher position. The whole process of machining must be controlled. Any error will have a serious impact on the mold quality, so the process design will play a decisive role in the machining quality. NC machining process design can be considered as the state control of a system process plan from the part blank to the part forming. A good process plan is difficult in the whole design process, which can be obtained only after continuous practice summary and modification. A large amount of information should be considered in the design process, and the relationship between the information is extremely complex, which must be guaranteed by the actual work experience of the programmer. Therefore, the design quality of process plan mainly depends on the experience and level of technical personnel.

Generally, a complete NC machining process planning includes the following contents:

1) CNC machine tool selection.

2) Processing method selection.

3) Determine the clamping mode of the part and select the fixture.

4) Positioning method.

5) Inspection requirements and methods.

6) Select the tool.

7) Error control and tolerance control in machining.

8) Define NC process.

9) Numerical control process sequencing.

10) Cutting parameter selection.

11) Work out NC process program sheet.

  1. CAM software a good software can also improve the quality and efficiency of mold processing, such as Unigraphics and cimiamtron , are very good mold processing software, especially the two kinds of software rich practical different processing strategy, in NC milling programming, turning programming, WEDM programming are widely used, complement each other, so that the quality and efficiency of NC machining has been greatly improved. Cimiamtron can add the screw function when clearing the offset area in rough machining, which will make the actual cutting more stable, eliminate the mutation of feed direction between adjacent tool paths, reduce the acceleration and deceleration of cutting feed, maintain a more stable cutting load, prolong the tool life, and also play a good role in protecting the machine tool. Software is just a tool. An excellent programmer has rich experience and theoretical knowledge of on-site machining. At the same time, the NC programmer who is proficient in the software function is the decisive factor in the mold NC machining, which plays a key role in the quality and efficiency of NC machining.
  2. The operator of machining center is the executor of NC machining, and their control of NC machining quality is also very obvious. In the process of performing processing tasks, they know the real-time status of machine tools, toolholders, cutting tools, processing technology, software and cutting parameters best, and their operations have the most direct impact on NC machining, so the skills and sense of responsibility of machining center operators are also the key factors to improve the quality of NC machining!

High precision parts manufacturing

  1. The concept, significance and characteristics of high precision parts manufacturing high precision parts manufacturing takes high precision mechanical parts as processing objects. Based on the systematic and integrated theory and technology, according to the structure and requirements of the workpiece, the organic combination and optimization of feeding, processing, detection and handling are realized, and the production of parts is completed under the precise processing conditions.
  2. Application field of high precision parts and components high precision parts and components are used in all walks of life testing equipment – scientific instruments. In China, they are mainly used in the instrument and instrument industry of scientific instruments.
  3. High precision machining has the advantages of high precision, low energy consumption, flexible production and high efficiency. Reducing the size of the whole manufacturing system and precision parts can not only save energy, but also save manufacturing space and resources, which is in line with the production mode of energy saving and environmental protection. It is one of the development directions of green manufacturing.
  4. Compared with ordinary machinery manufacturing, precision machinery manufacturing has high technology content (design and production), excellent processing equipment, high added value, and small batch sales.
  5. Analysis of foreign development situation high precision machinery manufacturing technology is known as one of the key technologies in the 20th century. It is the key development direction in the 21st century and has been highly valued by all countries in the world. Japan, the European Union, South Korea, the United States and other developed countries have invested a lot of human, material and financial resources to develop their own high-precision mechanical parts research and development and technology.
  6. China’s high-precision machinery manufacturing technology was gradually developed in the late 1980s and early 1990s. It is a rapidly developing industry in China today. High precision machinery manufacturing products are widely used in national defense, medical, aerospace, electronics and other military and civil fields.