Numerical control technology is the technology of controlling mechanical movement and working process with digital information. Numerical control equipment is a new technology represented by numerical control technology, which is suitable for mechanical and electrical integration of traditional manufacturing industry and emerging machining industry. It covers many fields of manufacturing, is the key equipment of modern manufacturing industry, and is the key equipment for enterprises to improve their efficiency and competitiveness.

The correct operation and maintenance of numerical control equipment is one of the key factors of correct use of teaching and control equipment. The correct operation and use can prevent abnormal grinding of machine tools and avoid sudden failures. Do a good day of maintenance, can make the equipment to maintain a good technical state, delay the deterioration process. Timely detection and elimination of hidden trouble to ensure safe operation

2. Problems to be paid attention to in the use of NC equipment

2.1 use environment of numerical control equipment

In order to improve the service life of numerical control equipment, it is generally necessary to avoid direct sunlight and other heat radiation, too wet, too much dust or corrosive gas places. Precision CNC equipment should be away from vibration equipment, such as punching machine, forging equipment, etc.

2.2 good power supply guarantee

In order to avoid the influence of large fluctuation amplitude of power supply (> ±10%) and possible instantaneous interference signal, numerical control equipment generally uses special line power supply (such as separate supply from low-voltage power distribution room for CNC hand-over machine tools) or the addition of voltage stabilizer, etc. Can reduce the quality of power supply and electrical interference.

2.3 Establishment of effective operating procedures

In the use and management of NC machine tools, a series of practical and effective operation rules should be formulated. Such as lubrication, moisturizing, rational use and standard shift system, is the main content of the use and management of digital control equipment. It is one of the important measures to ensure the safe operation of CNC machine tools to establish and control the operation rules. Practice has proved that many failures can be reduced by following the operation rules.

2.4 numerical control equipment should not be sealed for a long time

After purchasing the control machine tools, we should make full use of them, especially in the first year of operation, so that the weak links which are prone to malfunction can be exposed as soon as possible and can be eliminated during the warranty period. In machining, the opening and closing of the spindle of the NC machine tool is reduced as much as possible, and the wear of the clutch, gear and other devices is reduced by the barrier. When there is no processing task, the NC machine tool should also be powered on regularly, preferably once or twice a week. In order to reduce the humidity of the machine by making use of the calorific value of the machine tool for about 1 hour each time, the electronic components will not be dampened. At the same time, it can also detect the lack of battery power and alarm in time in order to prevent the loss of the system setting parameters.

3 maintenance of NC machine tools

There are many kinds of NC machine tools. Because of their different functions, structures and systems, all kinds of CNC machine tools have different characteristics. The contents and rules of its maintenance also have its own characteristics. It is necessary to formulate and establish the necessary regular and graded maintenance system according to the type, model and actual usage of the machine tool and the requirements of the manual for the use of the machine tool. Here are some common and common routine maintenance points.

3.1 maintenance of NC system

(I) strict compliance with operational rules and routine care systems

The operator should strictly observe the operation rules and the daily maintenance system, and the quality of the operator's technical service is an important factor in the occurrence of the accident. When the machine tool is damaged, the operator should pay attention to keeping the scene. And the maintenance staff truthfully explain the situation before and after the failure, in order to facilitate the analysis, diagnosis of the reasons for the original, timely elimination

(2) preventing dust and dirt from entering the numerical control unit

In the air of the machining workshop, there is usually oil fog, dust and metal powder. Once they fall on the circuit board or electronic device in the CNC system, it is easy to cause the electric resistance of the components and the insulation to drop. Even causing damage to components and circuit boards. In summer, in order to overload the CNC system for a long time, some users take the door of the CNC cabinet to dissipate heat, which is a very undesirable method, which will eventually lead to the accelerated damage of the CNC system. The opening of CNC cabinets and powerful cabinets should be minimized.

(3)  Prevention of overheating of the system

The cooling fans on the NC cabinets should be checked to see if they are working properly. Check the air duct filter every half a year or every quarter whether there is clogging phenomenon, if the dust accumulation on the filter too much, not enough time to clean up, will cause the temperature inside the CNC cabinet is too high

(4) regular maintenance of input / output devices of CNC system

Before the 1980s, most of the CNC machine tools produced before the 1980s, with optoelectronic paper reader, if the reading tape is partially contaminated, will lead to error in reading information. Therefore, the photoelectric reader must be maintained in accordance with the regulations.

(5) Periodic inspection and replacement of DC motor motors

The excessive wear of DC electromechanical system will affect the performance of motor and even the damage of motor. Therefore, it is necessary to conduct regular straightening and replacement of electric electromechanical system. CNC lathe, NC milling machine, machining center, etc., should be inspected once a year

(6) regular inspection and replacement of storage batteries

The general CNC system has a rechargeable battery maintenance circuit for the CMOS RAN memory device to ensure that the system does not keep the contents of its memory during the power off period. In general, the system should be replaced once a year, even if it has not yet expired, to ensure that the system works properly. Battery replacement should be carried out under the power supply condition of the NC system to prevent the loss of information in the RAM during the replacement

(7)  maintenance of standby circuit boards

When the spare printed circuit board is out of use for a long time, it should be installed in the CNC system for a period of time to prevent damage.

3.2 maintenance of mechanical components

(1)  maintenance of main transmission chain

Adjust the fastness of the main shaft driving belt regularly to prevent the phenomenon of losing rotation caused by the slippage of the belt; check the constant temperature oil tank lubricated by the spindle, adjust the temperature model, fill the oil in time, and clean the filter. After the tool clamping device in the spindle is used for a long time, the clearance will be produced, which will affect the clamping of the cutting tool, and the displacement of the piston of the hydraulic cylinder should be adjusted in time.

(2) maintenance of ball screw thread pair

Check and adjust the axial clearance of the screw thread pair regularly to ensure the accuracy and axial stiffness of the reverse drive; check regularly whether the connection between the lead screw and the bed is loose; and replace the lead screw protection device in time to prevent dust or chips from entering

(3) maintenance of tool store and tool changer manipulator

It is strictly forbidden to put the overweight and super-long tools into the tool storehouse to avoid the tool dropping or the tool colliding with the workpiece and the real tool when the manipulator changes the knife. Often check the correct position of the straight knife library, check whether the machine bed spindle tool return position is in place, open timely integration; When starting the machine, we should make the tool library and manipulator running empty, check whether all parts of the machine work normally, especially if the stroke switch and solenoid valve can work normally; whether the straightening tool is reliable on the manipulator, and if it is found to be abnormal, it should be dealt with in time

3.3 maintenance of hydraulic and pneumatic systems

Regular cleaning or replacement of filters or sub-filters for lubricating, hydraulic and pneumatic systems; oil quality testing, addition and replacement of hydraulic systems; and release of water from air sewer of pneumatic systems on a regular basis.

3.4 maintenance of machine tool accuracy

Check and correct machine tool level and accuracy regularly. There are two methods for correcting mechanical accuracy: soft and hard. The soft method is mainly through the compensation of system parameters, such as the compensation of the reverse clearance of the lead screw, the fixed point compensation of the coordinate positioning accuracy, the correction of the position of the machine tool back reference point, etc. Hard method should be carried out in machine tool overhaul, such as guideway repair and scraping, ball screw nut pre-tightening adjustment reverse clearance, etc.

4 concluding remarks

Numerical control equipment is a kind of advanced processing equipment with high degree of automation and complicated structure. In order to give full play to the high efficiency of numerical control equipment, it is necessary to operate correctly and maintain meticulously in order to ensure the normal operation and high utilization ratio of the equipment. It is a machine, electricity, liquid in one, so CNC equipment maintenance personnel requirements are high, in addition to the routine maintenance mentioned in this paper, but also according to the county CNC equipment operating instructions for specific maintenance and maintenance