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

The workpiece needs to be positioned and clamped before processing, which are two very important tasks. The purpose of clamping is to prevent the workpiece from displacement or vibration under the action of cutting force, gravity, inertia force, etc., so as not to damage the positioning of the workpiece. Therefore, the correctly designed clamping mechanism should meet the following basic requirements: 1. Clamping shall not damage the correct positioning of the workpiece; 2. The clamping device shall be rigid enough; 3. The workpiece surface shall not be damaged during clamping, and the workpiece shall not be deformed beyond the allowable range; 4. It can obtain the required clamping effect with a small clamping force; 5. Good processability. On the premise of ensuring productivity, the structure should be simple and convenient for manufacturing, maintenance and operation. The manual clamping mechanism shall have self-locking performance.

In the manufacture of tools and moulds, grinding is the last process to ensure the accuracy and quality of products. In addition to the grinding machine itself, the grinding process also plays a decisive role. When grinding brittle materials, due to the physical properties of the material itself, the formation of chips is mostly brittle fracture, and the surface after grinding agent is relatively rough. In some applications, such as optical elements, such a rough surface must be polished. Although it can improve the surface roughness of the workpiece, it is often reduced after polishing because it is difficult to control the shape accuracy. In order to solve this contradiction. In the late 1980s, many companies and research institutions in Japan, Europe and the United States successively pushed back two new grinding processes: plastic grinding and mirror grinding.

(1) The characteristics of plane parts are that the machined surface can be parallel to the horizontal plane, perpendicular to the horizontal plane, or at a fixed angle with the horizontal plane; At present, the vast majority of parts processed on CNC milling machines belong to plane parts. Plane parts are the simplest kind of parts in CNC milling processing. Generally, they can be processed only with two axis linkage or three axis linkage of three-axis CNC milling machines. In the process of machining, the machined surface is in surface contact with the cutter, and end mills or nose cutters can be used for rough and finish machining. (2) Curved surface parts, the characteristic of curved surface parts is that the machining surface is a spatial surface. In the machining process, the machining surface and the milling cutter are always in point contact. Ball end milling cutter is often used for surface finishing.

(1) CNC vertical milling machine. The spindle axis of CNC vertical milling machine is perpendicular to the horizontal plane. This kind of milling machine accounts for the majority of CNC milling machines and has the widest range of applications. At present, three-axis CNC vertical milling machines account for the majority of CNC milling machines, which can generally carry out three-axis linkage processing. (2) Horizontal CNC milling machine, the spindle axis of the horizontal CNC milling machine is parallel to the horizontal plane. In order to expand the processing range and expand the functions, the horizontal CNC milling machine usually adopts the way of adding CNC turntable or universal CNC turntable to realize four axis and five axis linkage processing. In this way, it can not only process the continuous rotary contour on the side of the workpiece, but also change the processing position of the part through the turntable in one clamping, that is, the commonly known station, to process multiple positions or working surfaces. (3) The spindle of this kind of milling machine can be converted, and the vertical and horizontal processing can be carried out on the same CNC milling machine. It also has the functions of vertical and horizontal milling machines.

1. The general lathe has a wide range of processing objects, and the adjustment range of spindle speed and feed rate is large. It can process the internal and external surfaces, end faces and internal and external threads of the workpiece. This kind of lathe is mainly manually operated by workers, with low production efficiency. It is suitable for single piece, small batch production and repair workshops. 2. Turret lathes and rotary lathes have turret tool holders or return wheel tool holders that can hold multiple tools. Workers can use different tools to complete a variety of processes in one clamping of workpieces, which is suitable for batch production. 3. The automatic lathe can automatically complete the multi process processing of small and medium-sized workpieces according to a certain program. It can automatically load and unload materials and repeatedly process a batch of the same workpieces. It is suitable for mass and mass production. 4. Multi Tool semi-automatic lathes are divided into single shaft, multi shaft, horizontal and vertical. The layout of the single shaft horizontal lathe is similar to that of the ordinary lathe, but the two groups of tool holders are respectively installed in the front and back of the spindle or above and below, which are used to process disc, ring and shaft workpieces, and their productivity is 3 ~ 5 times higher than that of the ordinary lathe. 5. The profiling lathe can imitate the shape and size of the template or sample and automatically complete the processing cycle of the workpiece. It is suitable for the small batch and batch production of workpieces with complex shapes. The productivity is 10 ~ 15 times higher than that of the ordinary lathe. There are many types, such as multi tool rest, multi shaft, chuck type, vertical type, etc. 6. The spindle of the vertical lathe is perpendicular to the horizontal plane, the workpiece is clamped on the horizontal rotary workbench, and the tool rest moves on the horizontal beam or column. It is suitable for processing large, heavy workpieces that are difficult to install on an ordinary lathe. It is generally divided into single column and double column. 7. While turning, the tool holder of the shovel lathe periodically makes radial reciprocating motion, which is used for forming the tooth surface of forklift milling cutters, hobs, etc. Usually with relief grinding accessories, a small grinding wheel driven by a separate motor is used to shovel and grind the tooth surface. 8. Special lathes are lathes used to process specific surfaces of certain types of workpieces, such as crankshaft lathes, camshaft lathes, wheel lathes, axle lathes, roll lathes and ingot lathes. 9. The combined lathe is mainly used for turning, but after adding some special parts and accessories, it can also be used for boring, milling, drilling, inserting, grinding and other processing. It has the characteristics of "one machine with multiple functions", and is suitable for repair work on engineering vehicles, ships or mobile repair stations.

As the reliability of modern CNC system is getting higher and higher, the faults of CNC system itself are getting lower and lower, and most of the faults are caused by non system reasons. The external faults of the system mainly refer to the problems caused by the detection switch, hydraulic components, pneumatic components, electrical actuating components, mechanical devices, etc. The external faults of numerical control equipment can be divided into software faults and hard faults caused by external hardware damage. Soft faults are caused by improper operation and adjustment. Such faults often occur in the early stage of equipment use or during the adjustment period of equipment users. For CNC system, another trouble prone place is servo unit. Because the movement of each axis is realized by the servo unit controlling the servo motor to drive the ball screw. The rotary encoder is used for speed feedback, and the grating ruler is used for position feedback. Generally, the driving module of rotary encoder and servo unit is prone to failure. There are also individual system chaos caused by power supply. Especially for those systems with computer hard disk to save data.

Numerical control system and drive unit are analyzed: 1. CNC system is the "brain" of CNC machine tools, which calculates and processes the control information of machine tools. According to the principle of CNC system, it can be divided into economic CNC system and standard CNC system. 2. Economical numerical control system, from the perspective of control method, economical numerical control system generally refers to open-loop numerical control system, which has the advantages of simple structure, low cost, convenient maintenance and debugging, low operation and maintenance costs, but the improvement of performance is limited by the torque frequency characteristics of stepping motor and the mutual restriction between accuracy, feed speed and torque. 3. Therefore, economical CNC system is often used in CNC wire cutting and some economical CNC lathes and milling machines with low speed and accuracy requirements. It is also widely used in the CNC transformation of ordinary machine tools. 4. Open loop CNC system means that the CNC system itself does not have a position detection device. The CNC system sends a certain number and frequency of command pulses, and the driving unit locates the machine tool. In the open-loop system, under the influence of external factors, the machine tool does not act or the action is not in place, but when the system has reached the specified position, the machining accuracy of the machine tool will be greatly reduced. 5. However, due to its simple structure, rapid response, stable and reliable work, convenient debugging and maintenance, and very low price, it still has the largest market in China.

1. Strictly abide by the operating procedures and daily maintenance system 2. The doors of numerical control cabinet and strong current cabinet should be opened as little as possible. Generally, there will be oil mist, dust and even metal powder in the air of machining workshop. Once they fall on the circuit board or electronic devices in the numerical control system, it is easy to cause the insulation resistance between components to drop, and even cause the components and circuit boards to be damaged. Some users open the door of the CNC cabinet to dissipate heat in order to make the CNC system work overload for a long time in summer. This is a highly undesirable method, which will eventually lead to accelerated damage to the CNC system. 3. Regularly clean the cooling and ventilation system of the digital control cabinet, and check whether each cooling fan on the digital control cabinet works normally. Check whether the air duct filter is blocked every half a year or every quarter. If the dust on the filter screen accumulates too much and is not cleaned in time, the temperature in the CNC cabinet will be too high. 4. For the regular maintenance of the input / output devices of the CNC system, most of the CNC machine tools produced before the 1980s are equipped with photoelectric paper tape readers. If the tape reading part is polluted, it will lead to the error of reading information. Therefore, the photoelectric reader must be maintained according to regulations. 5. Regular inspection and replacement of DC motor brushes. The excessive wear of DC motor brushes will affect the performance of the motor and even cause motor damage. For this reason, the motor brush should be checked and replaced regularly. CNC lathes, CNC milling machines, machining centers, etc. should be inspected once a year. 6. Regularly replace the storage battery. Generally, the CNC system has a rechargeable battery maintenance circuit for the CMOSRAM memory device to ensure that the content of its memory can be maintained during the period when the system is not powered on. In general, even if it has not expired, it should be replaced once a year to ensure the normal operation of the system. The battery shall be replaced under the power supply state of the CNC system to prevent the loss of information in RAM during replacement. 7. Maintenance of spare circuit board. When the spare printed circuit board is not used for a long time, it should be regularly installed in the CNC system and powered on for a period of time to prevent damage.

These determine the processing time, tool life and processing quality. An economical and effective machining method must be a reasonable choice of cutting conditions. The three elements of cutting conditions: cutting speed, feed rate and cutting depth directly cause tool damage. With the increase of cutting speed, the tool tip temperature will rise, resulting in mechanical, chemical and thermal wear. If the cutting speed is increased by 20%, the tool life will be reduced by 1/2. The relationship between feed conditions and tool back wear occurs in a very small range. However, with a large feed rate, the cutting temperature rises and the rear wear is large. It has less influence on the tool than the cutting speed. Although the influence of cutting depth on the tool is not as big as that of cutting speed and feed rate, the hardened layer of the material to be cut will also affect the service life of the tool in micro deep cutting. The user should select the cutting speed according to the processed material, hardness, cutting state, material type, feed rate, cutting depth, etc. The most suitable processing conditions are selected on the basis of these factors. Regular and stable wear is the ideal condition for reaching the service life. However, in practical operation, the choice of tool life is related to tool wear, machining size changes, surface quality, cutting noise, machining heat and so on. When determining the processing conditions, it needs to be studied according to the actual situation. For difficult to machine materials such as stainless steel and heat-resistant alloys, coolants or rigid blades can be used.

The processing technology of CNC lathe is similar to that of ordinary lathe, but because CNC lathe is a clamping machine, which can continuously and automatically complete all turning processes, the following aspects should be paid attention to. 1. Reasonable selection of cutting parameters: for high-efficiency metal cutting, the processed material, cutting tools and cutting conditions are the three major elements. 2. Reasonable selection of tools: (1) During rough turning, tools with high strength and good durability should be selected to meet the requirements of large back cutting and large feed during rough turning. (2) When finishing turning, we should choose tools with high precision and good durability to ensure the requirements of machining accuracy. (3) In order to reduce the time of tool change and facilitate tool setting, machine clamped knives and machine clamped blades should be used as much as possible. 3. Reasonable selection of fixtures: (1) Try to use general fixtures to clamp the workpiece and avoid using special fixtures; (2) The positioning datum of parts coincides to reduce the positioning error. 4. Determine the processing route: the processing route refers to the motion track and direction of the tool relative to the part during the processing of the NC machine tool. (1) It shall meet the requirements of machining accuracy and surface roughness; (2) The processing route should be shortened as far as possible to reduce the tool idle travel time. 5. Connection between machining route and machining allowance: At present, under the condition that the numerical control lathe has not reached universal use, it is generally necessary to arrange the excessive allowance on the blank, especially the allowance containing forged and cast hard skin, to be processed on the ordinary lathe. If it is necessary to process with a numerical control lathe, pay attention to the flexible arrangement of the program. 6. Key points of fixture installation: at present, the connection between the hydraulic chuck and the hydraulic clamping cylinder is realized by the pull rod. First, remove the nut on the hydraulic cylinder with the hand, remove the pull pipe, and pull it out from the rear end of the spindle, and then remove the chuck fixing screw with the hand, and then remove the chuck.