How to repair the failure of NC tool holder

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How to repair the failure of NC tool holder

as an important configuration of the stop switch to stop the operation of the CNC lathe, the tool rest plays a vital role in the operation of the machine tool. Once there is a fault, it is likely to cause the workpiece to be scrapped or even the accident of chuck and tool rest collision. In the fault maintenance of CNC machine tools, the circuit of the electrical control part is complex, and the fault phenomena are variable. Some fault phenomena are not clear. The materials and technologies such as high-performance thermoelectricity and power saving are obviously difficult to find, while the mechanical part is relatively similar to ordinary machine tools, and the faults are relatively easy to eliminate. When finding the cause of the fault, we should combine mechanical and electrical aspects to find it at the same time

I. CNC tool rest failure and treatment:

(I) failure causes and treatment of tool rest not in place or tool rest not locking:

1 Fault cause:

the following takes the lathe equipped with GSK980TD system (Guangzhou CNC system) as an example:

when the lathe is processing the workpiece excircle, the excircle cutter suddenly appears "stabbing". After the operator presses the "reset" button to return to the reference point, carefully check: first, check whether the cutter is loose or damaged, and then check whether the cutter is intact; Secondly, check whether the workpiece blank allowance is too large and meets the requirements after measurement; Since this phenomenon occurs midway, it is certain that there will be no problem with the processing program; Therefore, the operator suspected that the "tool compensation value" might be wrong. After re setting the tool, the "tool compensation value" was the same as the original; The cause of the fault is difficult to find out at the moment

the operator resets the machine tool system and improves the accuracy of the experimental results again The commissioning result of clamping another workpiece is normal. After processing several workpieces continuously, the same fault suddenly appeared again. After the above series of inspections, the cause of the fault was still not found. Finally, professional maintenance personnel were called. After communicating with the operator, the maintenance personnel first measured the input voltage and current of the machine tool system, and the results were normal. It was suspected that it might be a mechanical fault

therefore, when moving the vertical and horizontal carriage, starting the spindle, and rotating the tool rest in the manual test run, it was suddenly found that the tool rest was loose and did not lock automatically during the operation of the machine tool. It was judged that the tool rest system was faulty, but the "alarm number" was not displayed after the failure occurred in the processing process, so it must be the mechanical failure of the tool rest

after disassembling the tool rest, the maintenance personnel found that one spring positioning back-up pin inside was broken (four spring positioning back-up pins are equipped inside the NC Electric four position square tool rest) In the process of machining the workpiece, when the blank allowance is slightly large or the hardness is too high, the tool rest can automatically lock the tool when the unbroken spring positioning reverse pin of the tool rest rotates to a certain station is under force. The above fault occurs when the tool rest cannot automatically lock the tool rest when the broken spring positioning pin of the tool rest rotates to a certain station is under excessive force

2. Troubleshooting:

after the comprehensive inspection by the machine tool maintenance personnel, the electrical control part of the tool rest is normal, which is a mechanical fault. After replacing the broken spring positioning anti backup pin, install the tool rest and retest the fault, which has been eliminated

(II) fault causes and treatment of continuous operation of tool rest or non-stop of a tool position:

the following takes the lathe equipped with DTM system (digital control system of teitema) as an example:

1. Fault causes:

the phenomenon of continuous operation of tool rest or non-stop of a tool position occasionally occurs in the process of automatic operation of the lathe, and sometimes it stops and locks after continuous operation of 2~3 tool positions. When continuous operation or a tool position does not stop, the alarm "301" appears on the display screen (tool holder failure). The automatic operation of the machine tool stops. When the tool position stops for 2~3 consecutive operations and is locked, the alarm number is not displayed. The automatic operation of the machine tool is normal

because the fault is random and irregular, it is not easy to find the maintenance personnel. After inspection, it is determined to be an electrical control fault. The output voltage of the tool rest control system is tested to be normal, and the relay of the tool rest control system is also normal. Finally, disassemble the test items: tighten the protective cover at the top of the experimental tool holder and measure the input voltage of the hall element signal line one by one. The result shows that the copper core in the middle of one signal line is broken and temporarily connected by the wire protection rubber skin. When the tool holder turns to a certain position, the wire protection rubber skin is stressed and the two ends of the copper core wire cannot be connected normally. The program control system cannot find the corresponding tool number, and then there is an alarm of "301". When the tool holder is manually rotated to a certain position after the machine tool is reset, the wire protection rubber cover is loosened, and both ends of the copper core wire are connected. The tool holder rotates normally and no alarm signal appears

2. Troubleshooting:

after the maintenance personnel replaced the hall element connecting signal wire, the commissioning fault was eliminated, and the machine tool operated normally

III. summary:

by comprehensively analyzing the search and troubleshooting process of the above two faults, we can make it clear that the faults of CNC machine tools may occur not only in the electrical part, but also in the mechanical part. The CNC lathes equipped with the above two systems belong to the semi closed-loop control system and do not have the mechanical fault feedback function. During operation and use, daily maintenance and upkeep should be strengthened. If the "alarm number" is not displayed after a fault, it is likely to belong to the mechanical fault. During maintenance, the mechanical part should be mainly checked, which will be more accurate and timely for maintenance personnel to eliminate the fault

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