Correct use and preventive maintenance of CNC machine tools - News - Global IC Trade Starts Here.

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The service life cycle of the preventive maintenance equipment of CNC machine tools is divided into the new equipment running-in period, normal use period and state maintenance period. The key points of preventive maintenance at different stages are different. The performance, quality and function of CNC machine tools of different cattle manufacturers, crystal cards, imported or domestically produced machines are different, but the strategies and methods of preventive maintenance are basically similar. It is only on the frequency of some projects that perform preventive maintenance and on the basis of the characteristics of the machine tool to carry out targeted project repairs (referred to as item repairs).
1. Precautionary maintenance (data collection, necessary preparation) in the early stage of the equipment is a new equipment for installation and commissioning. For overhauled equipment or purchased second-hand equipment, it can also be referred to. After the installation and commissioning, you need to do the pre-preventive maintenance as described below.
(1) Data such as random drawings, manuals, machine tool accuracy test reports, adjustment test reports, parameter settings, procedures, tool cutters, etc., including paper and electronic documents.
(2) Detailed inspection, recording, and preservation of the original typical state data of the machine tool, such as the program, position, and coordinate system of the tool magazine, tool change, turntable in the specified position state and the specified tool number when all the same state and the automatic machining state are turned on. Basic data such as knife repair.
The abnormal state of CNC machine tools is manifested in alarm and plus. 1: Two aspects of precision anomaly. The original alarm has an operation error alarm and a fault alarm. The operation error type alarm can be easily eliminated by the alarm number range, and the fault alarm has the basic data comparison to speed up the identification of the fault point and severity, mechanical fault or electrical fault. For the processing accuracy problem, there is a basic data comparison to speed up the identification of the machine tool accuracy problem or the process chain f, 廿 J questions such as programming route, speed, the amount of machining and other processing parameters or tools, fixtures, materials, heat treatment and other original.
The collected data is used to record the self-diagnosis data under the conditions of no-load and certain working conditions in the specified operation mode. Such as I / O input and output status data; in the servo diagnosis I mother I face X, Y, Z, spindle, tool holder or MG tool magazine, ATC tool change, APC turntable and other servo drive axes and each additional CNC axis Percentage of load current; temperature and setting of the main shaft cooling constant temperature tank; temperature inside the electric box; hydraulic pressure and air pressure setting values. For a large number of screen data, you can use the method of photographing to quickly collect data; for precision CNC machine tools and large-scale CNC machine tools, such as fine-tuning r center, CNC grinding machine, etc., it is also necessary to use a vibration diagnostic measuring instrument to measure the meal machine, spindle or key position. Vibration status data. These data are important benchmark data necessary for future preventive maintenance of CNC machine tools, comparison of state detection and analysis, and judgment of changes in machine tool status. It is also an important reference data necessary for maintenance adjustment.
(3) The first oil change and fuel tank cleaning after 3-6 months of new machine tools are very important, including hydraulic oil tank, lubricating oil tank, main shaft cooling oil tank, rotary table deceleration oil tank, etc., aiming at solving the initial wear of the machine tool and the oil pollution. problem.
(4) Prepare equipment operating procedures and check cards. The operating procedures should be concise and outline the common operating methods and common fault reset methods; checkpoint cards should be simple and straightforward to list checkpoints, methods, standards and drawings.
(5) CNC machine tool technical support plan preparation: personnel training, data backup methods and means, spare parts planning, failure cause analysis and troubleshooting methods. Data backup is to read the numerical control system data through CF card, disk drive, PC, etc. (source: http://) including system parameters, PMC parameters, tool compensation data, Macro parameters, machining programs, electrical ladder diagrams, etc., electronic backup and print archive. Data security and operational policies must first be considered when backing up data. Spare parts planning should be prepared once in a technical manner, and then purchased in stages according to equipment status monitoring based on factors such as importance, estimated usage time, supply cycle and channel, and localization substitution. For non-mainstream CNC systems. Full consideration should be given to the problem of software and hardware upgrades and old version elimination after several years, and spare parts should be purchased in advance strategically.
Prepare the fault alarm number and troubleshooting method to establish a supplier contact channel.
2. Preventive maintenance during normal use of the equipment (plan execution, system adherence) The focus of preventive maintenance after the equipment is put into normal use is maintenance and safety. The premise is that the pre-stage preventive maintenance work must be done in order to give full play to the comprehensive advantages of CNC machine tool processing quality and efficiency.
Effective and long-term maintenance: l can significantly extend the life of CNC machine tools, maintaining accuracy and stability. Maintenance is divided into days, cycles, sizes, and levels, but the requirements are the same, and must be cleaned, lubricated, adjusted, and safe. Daily maintenance is mainly for internal and external cleaning, and it is necessary to check the oil level and oil quality. Refuel, check the safety device, and make simple adjustments. Periodic maintenance requires disassembly of the relevant protective cover to thoroughly clean and lubricate bearings, ball screws, linear guides, carriages, etc. Clean the inside of the electrical box. Check to clear the lubrication points. Clean the filter and apply a grease gun to the grease lubrication point. Carry out targeted preventive maintenance, check the same, change hydraulic oil, oil pressure calibration and so on. Check if the safety interlock is complete and interlocked.
Other aspects of maintenance: the temperature inside the electrical box should not exceed 55 ° C, the southern air-free workshop CNC machine tool electrical box should be equipped with air conditioning air cooler. Long-term use of CNC machine tools should pay attention to regular power-on warm-up operation, automatic lubrication, to avoid bearing, screw, carriage and other mechanical components rust. In the rainy weather, attention should be paid to the humidity caused by the condensation of the electrical box of the electrical box, especially near the machine door of the shop door and window.
The safety of CNC machine tools involves the design and manufacture of machine tools, and the various safety protection interlocks are well-designed, which has been finalized when the equipment is shipped from the factory. Use and maintenance. This is the key point that must be paid attention to in the safe use of CNC machine tools. Negligence of safety can cause collisions, damage to workpieces and tools, machine parts. Affect the accuracy of machine tools, but also endanger personal safety. Security for use and maintenance includes data security and operational security:
(1) Data security. In addition to the various data backups in the early stage of the equipment. The data memory backup support battery must be replaced regularly after the machine is turned off. If the battery alarm is not changed during the period, the absolute position of the CNC machine will be lost at zero, and the program and parameter settings will be lost, causing the CNC machine to crash. For alkaline batteries, the battery must be replaced once a year. It is necessary to use a brand-name iron shell high-performance battery to prevent the battery from leaking and corroding the system control board. For lithium batteries, the battery is usually replaced every 3 years.
Note: The battery must be replaced if the machine control system is energized and the machine emergency stop switch is pressed. Special reminder is that if the battery is connected incorrectly or the contact is poor, the storage contents will be lost. The length of battery life is related to the configuration of the system. It is inversely proportional to the length of the machine's power-off and the ambient temperature. That is, the longer the downtime, the higher the ambient temperature and the shorter the battery life. In addition, you must pay attention to the storage period of the battery.
(2) Set an umbrella. The essence of modern numerical control is computer numerical control, so it is necessary to specify the parameter modification authority. The numerical control parameter setting is the selection of various numerical control control modes and function switch on and off and the adjustment of control quantity. Therefore, the modification must be carefully used after fully understanding the meaning and function of its parameters, and the parameters are incorrectly set. Ir can damage the machine or workpiece and cause personal injury. The choice is reasonable. The town makes the machine tool normal I: and fully exerts its performance, and to some extent supports the safe use of CNC machine tools, reducing the impact of human error. The parameters of the CNC machine tool are divided into common parameters (user parameters) and encryption parameters (system function parameters), and the user can only modify the common parameters. Commonly used parameters to be mastered are machine zero, spindle orientation, tool magazine, tool change and turntable.
The parameters of the equipment at the factory are all the settings showing the maximum performance status. After the equipment is purchased, it needs to be based on the characteristics of the machined parts, materials, fixtures, and environment. Limit optimization of some parameter settings. The main parameters that need to be modified are: narrowing the positive and negative soft limit dimensions of the machine's motion stroke; the maximum speed of the spindle; the maximum speed of the fast motion; the maximum speed of the j-in; the rapid change of the ATC tool and the slow tool change. Avoid or reduce misuse of interference into the collision machine, reduce wear and tear, and help the CNC machine tool to be safe and long-lasting, stable and accurate use.
(3) Programming security. At the beginning of the program, instructions such as limiting the maximum speed of the abundance axis, limiting the constant line speed of the end face cutting, automatically returning to the reference origin, establishing the coordinate system, limiting the stored travel limit of the machining area, and preventing the interference check by the tool change are required.
3. Preventive maintenance during the maintenance period of the equipment state (status monitoring, sub-item repair) Under normal two-shift production, the CNC machine tool enters the state maintenance period after 5-6 years, while the equipment with preventive maintenance is good. After 10 years or even later, I will enter the state maintenance period. The characteristics of the equipment during this period are reduced accuracy and increased failure. The representation is that the tool holder or ATC tool change is more, the APC turntable has more faults, and the servo drive alarm has more faults. Most of the t-states are caused by mechanical failure and wear. In order to reduce maintenance costs, targeted repairs are required. Most of the servo drive alarms, which account for more than 75% of the fault alarms, are caused by wear or poor lubrication of bearings, ball screws or guide rails, resulting in a large mechanical load (source: http://) Thereby causing the servo drive current to increase. Overload alarm, accumulated in the sun and the moon, causing damage to the servo drive or servo motor. Therefore, the servo drive current and load percentage under the CNC machine tool diagnosis screen should be checked regularly, the change trend should be analyzed and recorded, and the timely repair, replacement or maintenance of bearings, lead screws or guide rails, adjustment of the plug iron tightness, etc. Can effectively reduce servo alarms and damage. Another cause of aging damage of the servo drive is the heat dissipation problem of the electrical box. Therefore, it is necessary to check the radiator and fan of the electric box cooler regularly. If equipped with an air conditioner, the cooling effect should be checked in addition to the above maintenance. Whether the refrigerant leaks.
Special reminder is that if the load is not well adjusted, the lubrication is poor, and the mechanical transmission chain has problems, the rigidity, mass and damping of the system are in a certain match, the system parameters are not properly set or the electrical system has problems, it will cause Self-excited vibration, resulting in the crawling and vibration of CNC machine tools, should be comprehensively analyzed and excluded.
Regularly monitor the accuracy of the machine, check the screw clearance, and confirm that the bearing is in good condition. r zone, through the manual pulse generator to check the positioning accuracy and backlash of each axis, determine the wear gap of the crowbar, comprehensive balance correction screw backlash parameters. For machine tools with high precision requirements, the ball screw should be replaced at the right time, and the laser range finder should be used for segmentation measurement compensation.
The machine's protective cover and associated seals should be inspected regularly during condition monitoring. Avoid the coolant entering the limit switch or the motor related interface, causing unnecessary electrical failures. Note that the X, Y-axis and other lower shields have poor chip removal. Damage the accuracy and service life of ball screws and guide rails. It will also cause the limit to send a false signal, and the accumulation of chips will also cause poor drainage and cause the water in the limit switch or the motor related interface. The motor is aging, the motor shaft leaks into the water, etc., causing abnormal electrical failure and damage.
The preventive maintenance of CNC machine tools runs through the entire life cycle of the equipment. Different equipments have different characteristics in different periods, and different maintenance strategies and targeted repair measures are needed. Institutionalized, effective, and targeted preventive maintenance of equipment can maximize the performance of the equipment and extend the life of the equipment.