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.
CNC lathe processing disadvantages:
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.
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.
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:
CNC computer gong processing machine precision and function debugging method:
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.
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.
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.
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.
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.
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.
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.
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.
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.