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Two ways to improve the validity of nc machine tool

Article source:admin Popularity:time:2017-07-07 17:39

Any a CNC machine to work reliably for a long time continuously, in addition to the quality of the machine tool itself factors, also in the process of using and maintenance, troubleshooting and timely correct and timely maintenance has a close relationship.
In order to improve the effectiveness of nc machine tools, maintenance should have two meanings: on the one hand, it is daily maintenance (preventive maintenance), which is to prolong the average time of failure of machine tools.
On the other hand, failure maintenance is intended to minimize the average repair time MTTR.
To do these two tasks is to give full play to the basic guarantee of equipment effectiveness.
 
In order to give full play to the benefit of nc machine tool, it is important to do preventive maintenance to make the nc system fail and improve the average working time of the system.
In addition, it should be ready for maintenance at any time. When the system fails, it can be repaired in time to minimize downtime.
The structure and properties of this request must be familiar with equipment, familiar with CNC system structure and basic operation, understand the system used on the printed circuit board for testing point for maintenance, to master its normal level and waveform, so that maintenance fault control and analysis.
In addition, the technical data of nc system and PLC (PLC) should be kept properly, and the typical parts program is commonly used.
According to the actual usage, some spare parts can be fitted properly, such as the insurance device, the brush, the transistor module and the printed circuit board.
For the spare circuit board, install regularly on the CNC system to operate, so as to avoid the failure of long-term use.
The key to preventive maintenance is to strengthen daily maintenance and maintenance, which usually should be done as follows:

1, the nc programming system for nc machine tools equipped with, operation and maintenance personnel should be familiar with mechanical structure of the equipment used, numerical control equipment, high voltage equipment, hydraulic system, gas path, such as the characteristics of each part, and the use of the environment, processing conditions, etc.
And strictly according to the machine tool and the numerical control device to use the instruction to correct, reasonably use the machine tool, try to avoid the failure due to improper operation.
 
Many systems use paper tape reading machines as input devices, system parameters, parts processors and other paper tape information, all of which must be entered into the CNC system through the tape reader.
If read take part of the paper tape reader (that is, the reading light and the light of the head part) with dirt, makes the read in the paper tape information error, so, on the surface of a read head, platen paper tape, paper tape channel surface should be regularly check and remove dirt in a timely manner.
For the moving parts of the paper tape reader, such as the active wheel roller, guide roller compaction roller, tensioning arm roller, etc. Should be cleaned frequently, and the lubrication is good.
 
3. Regularly clean air filters.
When installed on the door of cupboard of numerical control cabinet and electric air filter dust will cause more cooling air circulation inside ark, so for a long time, will cause temperature rise inside ark, make the system reliable work.
Therefore, it should be inspected at least once every six months according to the use of the environment.
The method is: remove the fastening screw first, remove the inner core of the air filter and blow the dust out of the filter by air.
Such as the filter is dirty, also can gently vibration filter at the same time, using the above method does not work, can use neuter cleaner (5% cleaner), but do not knead, dry it and then filter placed in a cool, ventilated place.
 
4. Regular battery maintenance.
In order to avoid the loss of parameters in the power outage, the power supply of the battery is maintained.
When the battery voltage is lower than CMOS, the battery can be charged automatically when the machine is switched on.
Normally, the accumulator can ensure that the information is stored for more than 1000h after the power failure. When the machine machine is not long, the battery should be switched on regularly according to the requirement of the manual, so that the battery can be recharged.
This kind of numerical control device if on CRT or the indicator light shows the battery failure alarm, indicates that the voltage is too low, the battery has failed, and the new battery needs to be replaced.
In order to save the original data, the battery should be replaced without the polarity of the battery.
 
The dc servo motor should be inspected and cleaned regularly.
Dc servo motor with brush, contact with the commutator contact friction and wear gradually.
The overwear of the brush can affect the performance of the motor and even damage the motor, so it must be checked and replaced regularly.
For general machine tools like numerical control lathe, CNC milling machine and machining center machine tools, can be inspected once a year;
For machine tools such as punch presses that frequent acceleration and deceleration work should be checked every two months.
When checking the power of the CNC system, and the motor has been completely cooled, first remove the brush cover, take out the brush, and measure its length, generally.
When the brush is worn to the half of the original length, it should not be used again, and the same type of new brush must be replaced.
The second step should be carefully check the curved contact surface of the brush and commutator contact for deep groove or cracks, and brush spring presence of strike a light trace, if you have the above phenomenon, must carefully check the surface of the commutator.
If the commutator is normal, a new brush can be replaced and checked again after a month.
If the above phenomenon occurs, it is necessary to consider whether the working conditions of the motor caused the motor to fail.
Before installing a new brush, clean the brush hole with clean compressed air without metal powder and moisture. Be sure to blow out the brush powder on the hole wall.
If it is hard to blow, use a screwdriver and other tools to help clean up until all the holes are clean.
But pay attention to avoid the screw blade tip damage commutator surface and hole wall.
Finally, load the new brush, tighten the cover, and make the servo motor to run for a period of time, so that the surface of the new brush is consistent with the commutator.
 
6. Pay attention to the closed CNC cabinet door.
In general, you should avoid opening the CNC cabinet door, especially the long open door.
The air filter should be cleared in time.
There is no way to dissipate heat by opening the door.
Because the floating in the air inside the shop have a lot of dust, oil mist, and metal powder, etc., these debris falls on the PCB and electronic components, easily cause the loss of components insulation resistance and failure, and even make the damage of components and printed circuit board scrap.
In particular, the control system installed in the main shaft control system is installed in the power cabinet. If the door is not tightly closed or sealed, the main shaft control will fail.
 
7. Regularly clean the cooling device and enhance the heat dissipation effect.
Some servo motor or spindle motor on the casing is equipped with forced cooling device, if the cooling device protection network or heat sink is very dirty, influence the air circulation, must reduce the cooling capacity, the failure due to heat loss.
Therefore, these cooling devices should be cleaned regularly. The specific method is: if the dust is too much to prevent ventilation, remove it for cleaning;
When the heat sink is a lot of dust, you can use compressed air to blow clean, or remove dust from the middle of the heat sink.
But the operation should be careful not to squeeze the heat sink, and overlap, so as not to affect the heat dissipation effect.
The above cleaning cycle is generally for every six months, also can be shortened according to the specific situation.
 
8. For long - term numerical control machine tools, the CNC system should be used to power the CNC system, so that the machine can be operated without moving.
In the southern plum rain season that the air wetness is larger should be daily electricity, use the heat of the electrical components of the device itself to drive away the moisture of the numerical control cabinet.
To ensure the stability and reliability of circuit performance.
It has been proved that all kinds of failures are easy to occur after the machine is not used.
If the CNC machine is idle for more than half a year, the dc servo motor should be removed, so as not to be corroded on the surface of the commutator by chemical action, the commutation performance will deteriorate and even damage the motor.
 
9, the parts that move frequently on machine tool, whether from mechanical or controlling, should be inspected regularly.
In order to ensure the reliability of machine tools, a number of travel switches are adopted to limit the position of the machine.
The reliability of these travel switches directly affects the reliability of the whole machine.
Moreover the automatic tool change device on the mechanical and electrical machine tool structure is complex, is prone to failure, so often should check control library choose knife and positioning the status of the electrical system, position detection system is the working condition of stroke switches, to ensure the machine can run normally.

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