In order to give full play to the role of CNC lathe, reduce the occurrence of faults and extend the mean time between failures of machine tools. The programming, operation and maintenance personnel of CNC machine tools must receive special technical training and have knowledge of processing technology, hydraulics, measurement and automatic control, so as to fully understand and master CNC machine tools and do a good job in maintenance and maintenance.

1. Contents and requirements of daily maintenance of CNC lathes

CNC lathe operators should strictly abide by the operating rules and daily maintenance system of the machine tool, operate the machine tool correctly and reasonably in strict accordance with the requirements of the machine tool and system manual, and try to avoid the influence of improper operation on the use of the machine tool.

Serial number inspection cycle inspection site inspection content and requirements

1 check the oil level and quantity of the lubricating oil tank of the guide rail every day, add lubricating oil in time, and the lubricating pump can start and stop refueling in time.

2 Remove the debris and dirt on the guide surface of X axis and Z axis every day, and check whether the lubricating oil is sufficient and whether the guide surface is scratched or damaged.

3 check the pressure of pneumatic control system with compressed air source every day, which should be within the normal range.

Each weather source automatically feeds water into the water filter, and the automatic air dryer cleans the water filtered by the water separator in time to ensure the normal operation of the automatic air dryer.

When the oil level of pneumatic converter and supercharger is insufficient every day, it is necessary to replenish oil in time.

6 Every day, the spindle lubrication constant temperature oil tank works normally, with sufficient oil and suitable working range.

Every day, the balance pressure of the hydraulic balance system indicates normal, and the balance valve works normally when it moves rapidly.

8 Check the oil tank and oil pump of the hydraulic system of the machine tool every day for no abnormal noise, the pressure gauge indicates normal, the pipelines and joints are free of leakage, and the working oil level is normal.

9 Every day, the cooling fan of the cooling ventilation device of the electric cabinet works normally, and the air duct filter is not blocked.

10 CNC input/output equipment check the cleanliness of I/O equipment and the good lubrication of mechanical structure every day.

1 1 There should be no looseness and water leakage on the guide rail and machine cover of various protection devices every day.

12 Clean the filter screen of each electrical cabinet once a week.

13 irregularly cools the oil tank and water tank. Check the liquid level at any time and add oil or water in time. If it is too dirty, the cleaning oil tank, water tank and filter need to be replaced.

14 Irregular waste oil pool takes away the stored waste oil in time to avoid overflow.

15 irregular chip cleaner often cleans chips and checks whether it is blocked, etc.

16 Check the spindle drive belt irregularly. The manual requires adjusting the belt tightness. If the belt is damaged, it should be replaced in time.

17 According to the machine tool manual, irregularly check the rounded corners on the guide rails of each shaft and adjust the tightness of the press roller.

18 Clean the old grease on the ball screw every six months and apply new grease.

19 Clean the overflow valve, pressure reducing valve, oil filter and oil tank in the hydraulic oil circuit once every six months, and replace or filter the hydraulic oil.

Every year, the spindle lubricates the thermostatic oil tank, cleans the filter and changes the lubricating oil.

2 1 check and replace the brush of DC servo motor every year. Check the commutator surface, blow off the toner, remove the burr and replace the brush with too short length.

Lubricating oil pump and filter clean the bottom of lubricating oil pool every year and replace the oil filter.

2. Daily maintenance of mechanical structure

CNC lathe is an automatic machine tool with mechanical, electrical and hydraulic functions. Through the execution function of each part, the movement, rotation, clamping, loosening, speed change and tool change of the mechanical actuator are finally completed. It can be seen that the daily maintenance of the mechanical actuator of the CNC lathe will directly affect the performance of the machine tool. The daily maintenance of mechanical structure of CNC lathe mainly includes the maintenance of lathe bed, spindle parts, ball screw nut pair and guide rail pair.

(1) Appearance maintenance

(1) Do a good job of cleaning the machine tool every day, clean the iron filings and clean the coolant at the guide rail. After work, all machined surfaces are coated with antirust oil to prevent the guide rail from rusting.

(2) Pay attention to check whether the guide rail and machine tool shield are complete and effective every day.

③ Check the inside and outside of the machine tool for bumps, bruises and strains every day.

(4) Regularly remove debris and oil stains from all parts to ensure that there is no dead angle, and keep the inside and outside clean and free from corrosion.

⑵ mainshaft maintenance

In the CNC lathe, the spindle is the most critical component, which plays a decisive role in the machining accuracy of the machine tool. Its rotary accuracy affects the machining accuracy of the workpiece, and the power and rotating speed affect the machining efficiency. The maintenance of mechanical structure of spindle components mainly includes spindle support, transmission and lubrication.

① Regularly check the spindle support bearing: insufficient preload of the bearing, or loose preload screw and excessive clearance will cause the spindle to move axially, which should be adjusted in time; Bearing hair or damage should be replaced in time.

(2) Regularly check the spindle lubrication constant temperature oil tank, timely clean the filter and replace the lubricating oil. , to ensure good lubrication of the spindle.

③ Check the gear set regularly. If there is serious damage or the gear meshing clearance is too large, replace the gear and adjust the meshing clearance in time.

(4) Check the spindle drive belt regularly, adjust the belt tightness or replace the belt in time.

(3) Maintenance of ball screw nut pair

Ball screw drive has the advantages of high transmission efficiency, high transmission accuracy, stable movement, long service life and elimination of pre-tightening clearance, and is widely used in CNC lathes. Its daily maintenance includes the following aspects:

① Regularly check the axial clearance of the ball screw nut pair: under normal circumstances, the clearance can be eliminated by automatic compensation of the control system; When the gap is too large, it can be ensured by adjusting the ball screw nut pair. The ball screw nut pair of CNC lathe mostly adopts double nut structure, and the clearance can be eliminated by pre-tightening the double nuts.

② Check the screw protective cover regularly: to prevent dust and abrasive particles from sticking to the screw surface, which will affect the service life and accuracy of the screw. If the screw guard is damaged, it should be repaired and replaced in time.

③ Regularly check the lubrication of ball screw nut pair: The lubricant of ball screw nut pair can be divided into grease and lubricating oil. Grease is not changed every six months. Remove the old grease from the lead screw and coat it with new grease. The roller screw nut pair with lubricating oil can be oiled once before each machine operation.

④ Check the support bearing regularly: check whether the connection between the screw support bearing and the machine tool is loose and whether the support bearing is damaged. If so, tighten loose parts and replace the support bearing in time.

⑤ Regularly check the connection between the servo motor and the ball screw: the connection between the servo motor and the ball screw must ensure that there is no gap.

(4) Maintenance of guide rail pair

Guide pair is an important executive part of CNC lathe, and there are common sliding guide and rolling guide. The maintenance of guide rail pair is generally irregular, and the main contents include:

(1) Check the strips on the guide rails of each shaft and press the rollers to ensure a reasonable gap between the guide surfaces. Adjust the tightness according to the machine instructions. Clearance adjustment methods include platen clearance adjustment, insert clearance adjustment and platen insert clearance adjustment.

② Pay attention to the lubrication of the guide rail pair: After the surface of the guide rail is lubricated, the friction and wear can be reduced and the guide rail can be prevented from rusting. According to the lubrication condition of the guide rail, adjust the lubricating oil quantity of the guide rail in time to ensure the lubricating oil pressure and good lubrication of the guide rail.

③ Check the guide rail cover frequently: to prevent debris, abrasive particles or coolant from scattering on the guide rail surface, causing abrasion, abrasion and corrosion. If the protective cover is found to be damaged, it should be repaired and replaced in time.

3. Daily maintenance of electrical control system

The electrical control system of CNC lathe is the key part of the machine tool, which mainly includes servo and detection device, PLC, power supply and electrical components. Its daily maintenance includes the following aspects:

(1) Check the electrical components regularly, and check whether there are poor contacts and short-circuit layer faults in plugs, sockets, cables and relay contacts; Check whether each printed circuit board is clean; Check whether the insulation loop of the main power transformer and motor is above 1mω. Usually try to open the door of the electric cabinet as little as possible and keep it clean.

⑵ Maintenance of DC servo motor

In 1980s, most CNC machine tools used DC servo motors, which led to the problem of brush wear. Therefore, DC servo motors need to be inspected and replaced regularly.

(1) Daily maintenance inspection during machine tool operation. Observe the rotating speed during operation; Whether there is abnormal vibration and noise; Whether there is abnormal smell; Check the temperature of motor housing and bearing.

② Regular maintenance. Because the DC servo motor has several pairs of brushes, when it rotates, the brushes rub against the commutator and gradually wear out. Abnormal or excessive wear of brushes will affect the working performance, so it is necessary to carry out daily maintenance of DC servo motor. Check and replace DC motor brushes regularly.

The DC servo of CNC lathe should be checked once a year, and the inspection steps are as follows:

Check when the CNC system is in a power-off state and has completely cooled down.

Remove the rubber brush cap, unscrew the brush cap with a screwdriver, and take out the brush.

Measure the brush length. If the brush of FANUC DC servo motor is worn from 10mm to 5mm, it must be replaced with a new brush of the same model.

Carefully check whether there are deep grooves or cracks on the arc contact surface of the brush, and whether there are fire marks on the brush spring. If there is the above phenomenon, we should consider whether the working conditions are too harsh or there is something wrong with it.

The compressed air without metal powder and moisture is poured into the brush holding hole where the brush is installed, and the brush powder stuck on the wall of the brush holding hole is blown off. If it is difficult to blow clean, gently clean it with the tip of a screwdriver until the hole wall is completely clean, but be careful not to touch the commutator surface.

Reinstall the brush and tighten the brush cover. If a new brush is replaced, it needs to run in the air for a period of time to make the brush surface and commutator surface soft and good.

(3) Maintenance of AC servo motor

Compared with DC servo motor, the biggest advantage of AC servo motor is that there is no problem of brush maintenance. The AC servo motor used for feed drive mostly adopts AC permanent magnet synchronous motor, which is characterized in that the magnetic pole is rotor, the armature winding of the stator is the same as the three-phase AC armature winding, but the power is supplied by a three-phase inverter, and the switching devices of the stator winding are controlled by signals generated by detecting the rotor position, so that they are turned on in turn to realize phase commutation, thus making the rotor rotate continuously. The rotor position detector is installed coaxially with the rotor for detecting the position of the rotor. The detection device is generally a Hall switch or a photoelectric pulse encoder with phase detection.

(4) Drive maintenance

General drive maintenance is 1-3 years. The maintenance method is as follows: clean the circuit board thoroughly with industrial alcohol when starting the machine, then blow dry the circuit board absolutely with a hair dryer, and then observe whether the components on the circuit board are deformed and short-circuited, whether the power supply device is in contact with oxidation, whether the capacitor is bulging, handle it carefully step by step, and finally replace the fan, but pay attention to the speed and stability of the fan and don't screw things up.

5] DC power supply maintenance

In general, the DC power supply is maintained once every 1-3 years. The maintenance method is as follows: first find a big light bulb to discharge, turn it on, clean it first, then dry it, and then observe whether there is pollution-free oxidation on the circuit board. Because the voltage and current are relatively large, first make sure there is no virtual short circuit and interference between the lines, and then observe whether the components on the circuit board are deformed or directly damaged. Because the comprehensive performance of industrial products is better, the range of choice is relatively large. Using components is not necessarily good. Take the capacitor as an example. If it leaks once or twice, it can still be used sometimes, but the service time will definitely be shortened and the whole machine may be scrapped. Therefore, we must do a good job of maintenance, and finally ensure that the fan is good and the air duct is smooth.

[6] ⑹PLC maintenance

In general, PLC is maintained once every three years. Maintenance methods are as follows: program backup, machine startup, cleaning first, and then drying. Mainly observe the power supply part and input and output part of each module to see if there are any components with poor performance. The CPU module should wash hands to reduce static electricity, then operate, and finally make sure the battery capacity is normal. If the capacity is reduced, it is best to replace it with electricity.

Man-machine interface maintenance once

Man-machine interface maintenance is generally done once every three years. The maintenance method is as follows: remove the static electricity from your hands, clean the circuit board, then dry it and observe the power supply part. If the capacitance performance is poor, replace the lamp tube, paying special attention to the good contact between the connectors. Finally, it is necessary to deal with the seal between the man-machine and the front cover to reduce the entry of dust.

Being spare circuit board is prone to failure without long-term use, so the spare circuit board of CNC machine tools should be installed on CNC machine tools regularly and powered on for a period of time.

Levies CNC lathe should be started regularly when it is not used for a long time, especially in rainy season when the air humidity is high. Electrical components should be electrified every day to ensure the stable and reliable performance of electrical components.

In a word, the daily maintenance of the electrical control part of the CNC lathe is very important. It is necessary to observe the relevant operating procedures and be cautious, and pay attention to the following aspects:

(1) Wash your hands before you start.

⑵ Record the external wiring of the machine.

(3) If you bring your own user program, you should back it up first.

(4) The dip switch inside the machine shall be recorded.

5] Make records before replacing parts.

[6] The welding circuit shall ensure that the solder joints are firm and shall not be short-circuited with other components.

After installation, the fixed parts should be installed firmly.

Being recorded the specific situation of the whole machine, so that the next maintenance.

4. Maintenance of hydraulic transmission system

Hydraulic transmission system plays an important role in the mechanical control and system adjustment of CNC lathe, such as shifting of hydraulic chuck and headstock, lubrication of spindle bearing and machine tool tailstock, so effective daily maintenance can ensure the normal work of CNC lathe. The daily maintenance points of hydraulic transmission system are as follows:

(1) Keep the hydraulic oil clean. Hydraulic oil pollution is not only the main cause of hydraulic system failure, but also accelerates the wear of hydraulic components, so controlling hydraulic oil pollution is one of the important tasks to ensure the normal work of CNC lathes.

(2) Strictly implement the routine inspection system. The fault of hydraulic system is hidden, variable and difficult to judge. Therefore, it is necessary to do a good job in the routine inspection of the hydraulic system, strengthen the daily routine inspection records, and ensure the normal work. The spot check of hydraulic system includes the following contents:

① Whether the cursor in the fuel tank is within the cursor scale; Whether the oil temperature is within the allowable range.

(2) Whether there is leakage at each hydraulic valve, hydraulic cylinder and pipe joint; Whether the pressure of each pressure measuring point of the hydraulic system is within the specified range and whether the pressure is stable.

③ Whether the hydraulic pump or hydraulic motor is running abnormally; Whether the hydraulic cylinder moves normally and smoothly; Whether the manual or automatic working cycle of hydraulic system is abnormal; Whether the electric or collision controlled reversing valve is flexible and reliable.

(4) regularly check and clean the oil tank and pipeline; Check, clean or replace the filter element regularly; Check, clean or replace hydraulic components regularly.

⑤ Check and replace the seal regularly; Regularly check and tighten screws, nuts, joints and flanges in important parts; Regularly check whether the position of the travel switch or stopper is loose.

⑥ Regularly check the performance of cooler and heater.

⑦ Regularly check the working performance of the accumulator.

5. Maintenance of CNC system

CNC system is the core of CNC machine tools. There are mainly two kinds: one is a special hardware numerical control device (NC device) composed entirely of hardware logic circuits, and the other is a computer numerical control device (CNC device) composed of computer hardware and software. With the development of computer technology, numerical control equipment is mainly numerical control devices. Numerical control device consists of hardware control system and software control system, and its daily maintenance mainly includes the following aspects:

(1) Strictly formulate and implement the rules and regulations for daily maintenance of CNC system. According to the performance characteristics of different CNC machine tools, the rules and regulations of daily maintenance of CNC system are strictly formulated and strictly implemented in use and operation.

⑵ Try to open the doors of CNC cabinet doors and high-voltage cabinets as little as possible. The air in machining workshop often contains oil mist and dust. Once they fall on the printed circuit board or electrical components of the numerical control system, it is easy to cause the insulation resistance of the components to drop, and even lead to the damage of the circuit board or electrical components.

(3) Regularly clean the cooling and ventilation system of the numerical control device to prevent the numerical control device from overheating. Cooling and ventilation system is an important device to prevent overheating of numerical control equipment. Therefore, it is necessary to check whether the cooling fan on the numerical control cabinet works normally every day, and check whether the air duct filter is blocked every six months or every quarter. If there is, clean it up in time.

(4) Pay attention to the regular maintenance of the input/output equipment of the numerical control system. Such as cleaning the magnetic head in the input device of the numerical control system.

5] often monitor the grid voltage of numerical control equipment. The numerical control system has strict requirements for the working grid voltage. For example, the numerical control system produced by FANUC allows the grid voltage to fluctuate within the range of 85% ~ 1 10% of the rated value, otherwise the numerical control system will not work normally and even damage the electronic components inside the numerical control system.

[6] Check and replace the stored batteries regularly. In numerical control system, some storage contents in CMOS memory are saved by battery power supply when power is cut off. Lithium batteries or rechargeable nickel-cadmium batteries are generally used. When the battery voltage drops to a certain value, the data will be lost, so it is necessary to check the battery voltage regularly. When the battery voltage drops to the limit value or battery voltage alarm occurs, the battery should be replaced in time. When replacing the battery, it is usually carried out when the numerical control system is powered on, which will not cause the loss of storage parameters. Therefore, machine tool parameters should be backed up. Once the data is lost, you can re-enter the parameters after replacing the battery.

Once the daily maintenance of the software control system must be done: the parameters of the machine tool cannot be changed at will, and the modification record must be made if the parameters need to be modified.