CNC machine tools are a typical technology-intensive automatic processing equipment integrating mechanical, electronic, hydraulic, optical and measurement technologies. This paper discusses the common faults and preventive measures of CNC machine tools, and puts forward some views on how to use CNC machine tools reasonably to reduce their mechanical failures.
With the introduction and popularization of a large number of numerical control equipment, quite high requirements have been placed on the maintenance and repair of equipment. The key to the maintenance of CNC machine tools is the accurate diagnosis of faults, that is, the search for fault sources and the location of faults. CNC machine tools common mechanical failure spindle component failure Due to the use of speed control motor, CNC machine tool spindle box structure is relatively simple, the part that is prone to failure is the tool automatic clamping mechanism inside the spindle, automatic speed control device. In order to ensure that the tool holder will not loosen during work or during power failure, the automatic clamping mechanism of the tool is spring-clamped and equipped with a travel switch to signal the clamping or relaxation. If the tool cannot be loosened after clamping, consider adjusting the loose cylinder pressure and the stroke switch device or adjusting the nut on the disc spring to reduce the amount of spring compression. In addition, the problem of spindle heating and headstock noise can not be ignored. At this time, it is mainly considered to clean the spindle box, adjust the amount of lubricating oil, ensure the cleanliness of the spindle box and replace the spindle bearing, repair or replace the spindle box gear. Feed chain failure In the CNC machine feed drive system, ball screw pairs, static screw nut pairs, rolling guides, static pressure guides and plastic guides are commonly used. Therefore, the feed transmission chain is faulty, mainly reflecting the deterioration of the motion quality. For example, the mechanical parts do not move to the specified position, the operation is interrupted, the positioning accuracy is decreased, the backlash is increased, the creeping, the bearing noise is increased (after the collision), and the like.
For such failures, the following measures can be taken: (1) Improve the transmission accuracy. Adjust the pre-tightening force of each movement pair, adjust the loosening link, eliminate the transmission gap, shorten the transmission chain and set the reduction gear in the transmission chain, and also improve the transmission precision. (2) Improve the transmission stiffness. Adjusting the pre-tightening force of the screw nut pair and the supporting member and reasonably selecting the size of the screw itself, is an effective measure to improve the transmission rigidity. Insufficient stiffness can also cause crawling and vibration of the workbench or pallet and cause reverse dead zones, affecting transmission accuracy. (3) Improve the accuracy of motion. Under the premise of satisfying the strength and rigidity of the component, the mass of the moving component is reduced as much as possible, and the diameter and mass of the rotating component are reduced to reduce the inertia of the moving component and improve the motion precision. (4) Guide rails. The rolling guide is sensitive to the object, and it must have good protection, and the pre-tightening force of the rolling guide should be properly selected, and the traction force is significantly increased. The hydrostatic guide should have a well-filtered oil supply system. The automatic tool change device failure automatic tool change device failure mainly manifests in: tool magazine motion failure, positioning error is too large, the robot grip holder is unstable, and the manipulator motion error is large. When the fault is serious, the tool change will be stuck and the machine will be forced to stop working.
(1) Tool magazine motion failure If the coupling of the motor shaft and the worm shaft is loose or the mechanical coupling is too tight, the tool magazine cannot be rotated. In this case, the screws on the coupling must be tightened.
If the tool magazine is not rotated, it is caused by motor rotation failure or transmission error. If the current tool holder cannot clamp the tool, adjust the adjusting screw on the knife sleeve, press the spring, and tighten the clamping pin. When the upper/lower position of the knife sleeve is not in place, check the installation and adjustment of the dial position or limit switch.
(2) Tool changer failure If the tool holder is not tight and the tool is dropped, adjust the clamping claw spring to increase the pressure or replace the robot clamping pin. If the tool does not open after clamping, adjust the nut behind the loose lock spring so that the maximum load does not exceed the rated value. If the tool is lost when the tool is exchanged, the spindle box does not return to the tool change point or the tool change point drifts when the tool change occurs. The spindle box should be re-operated to return to the tool change position and reset the tool change point. Each shaft movement position stroke switch pressing fault is on the CNC machine tool. In order to ensure the reliability of the automation, a large number of stroke switches for detecting the movement position are adopted. After long-term operation of the machine tool, the movement characteristics of the moving parts change, the reliability of the stroke switch pressing device and the change of the quality characteristics of the stroke switch itself have a great influence on the performance of the whole machine. Generally, it is necessary to check and replace the travel switch in time to eliminate the influence of the poor switch on the machine tool. Auxiliary device failure hydraulic system. The hydraulic pump should use a variable pump to reduce the heat generated by the hydraulic system. The filter installed in the fuel tank should be cleaned regularly with gasoline or ultrasonic vibration. Common faults are mainly pump body wear, cracks and mechanical damage. At this time, it is generally necessary to overhaul or replace parts.
Pneumatic system. In the air pressure system for tool or workpiece clamping, safety guard door switch and spindle cone blower, the water separator should be regularly drained and cleaned regularly to ensure the sensitivity of moving parts in pneumatic components. Failures such as valve heart failure, air leakage, damage to pneumatic components, and malfunctions are caused by poor lubrication, so the oil mist eliminator should be cleaned regularly. In addition, the tightness of the pneumatic system should always be checked.
Lubrication system. Includes lubrication of machine guides, drive gears, ball screws, headstocks, etc. The filter in the lubrication pump needs to be cleaned and replaced regularly, and it should be replaced once a year.
cooling system. It cools and smashes the tool and workpiece. The coolant nozzle should be cleaned regularly.
Chip removal device. The chip removal device is an accessory with independent functions, which mainly ensures the smooth progress of automatic cutting and reduces the heat generation of the CNC machine. Therefore, the chip removal device should be able to automatically remove chips in time, and the installation position should be as close as possible to the tool cutting area. Reasonable use of CNC machine tools CNC machine tool selection (1) Avoid direct sunlight and other heat radiation, avoid too humid or excessive dust. Try to use in air-conditioned environment, keep room temperature around 20 °C. Because China is in a temperate climate, affected by the monsoon, and the temperature difference is large, for high precision and expensive CNC machine tools, it should be used in air-conditioned rooms.
(2) Avoid places with corrosive gases. Corrosive gases tend to deteriorate electronic components, cause poor contact, or cause short-circuiting of components, affecting the normal operation of the machine.
(3) Keep away from equipment with high vibration (such as punching machines, forging equipment, etc.). For high-precision machine tools, anti-vibration measures (such as anti-vibration ditch) should also be used.
(4) Keep away from strong electromagnetic interference sources and make the machine work stable. The power supply CNC system of CNC machine tools has strict requirements on power supply. Generally, the working voltage is 220V 10%. For the power supply conditions in China, for qualified enterprises, special line power supply or voltage regulators can be added for CNC machine tools to reduce the influence of poor power supply quality, which provides a strong guarantee for the normal operation of the CNC system. CNC machine tools are equipped with an appropriate automatic programming system. Manual programming is simple and easy for parts programs that are not too complicated or have a small amount of programming. When the workpiece is more complicated, such as cam or multi-dimensional space surface, etc., the manual programming cycle is long (several days or weeks), the precision is poor, and it is easy to make mistakes. Therefore, the rapid and accurate programming of the program becomes an important part of improving the utilization rate of CNC machine tools: for this reason, users with conditions are better equipped with the necessary automatic programming system to improve programming efficiency. CNC machine tools are equipped with the necessary accessories and tools in order to fully utilize the machining capabilities of CNC machine tools, and must be equipped with the necessary accessories and tools. Don't spend hundreds of thousands of dollars to buy a CNC machine tool, which affects the normal operation of the whole machine due to the lack of a tens or hundreds of accessories or tools. Since the price of the accessory purchased separately by the contract is much higher than the unit price of the accessory supplied with the host. Therefore, qualified companies try to purchase consumable parts and other accessories when purchasing the host.
Plug-In Connecting Terminals,Insulated Spade Terminals,Cable Connector Double Spade Terminals,Vinyl-Insulated Locking Spade Terminals
Taixing Longyi Terminals Co.,Ltd. , https://www.lycopperlugs.com