[CNC lathe tool post maintenance] The reasons why the CNC tool post keeps turning and the common faults and solutions of the CNC tool post
CNC The cause and treatment of the inaccurate positioning of the tool post or the inability to lock the tool post
1, the cause of the failure
The following takes the lathe equipped with GSK980TD system (Guangzhou CNC system) as an example:
When the lathe is machining the outer circle of the workpiece, the outer cutter suddenly appears “sticking the cutter” until the operator presses “reset” After the button is returned to the reference point, check carefully: first, check whether the tool is loose or damaged. After checking, the tool is in good condition; secondly, check whether the workpiece blank allowance is too large and meets the requirements after measurement; because this phenomenon occurs in the middle, it is certain that there will be no problem with the processing program; Therefore, the operator suspects that the “tool compensation value” may be changed to the wrong one. After re-setting the tool, the “tool compensation value” is the same as the original; the cause of the failure is difficult to find out for a while.
The operator resets the machine tool system and re-clamps another workpiece and the test run results in normal operation. After continuous processing of several workpieces, 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 found. After communicating with the operator, the maintenance personnel first measured the input voltage and current of the machine tool system. The results were normal and suspected mechanical failure.
Then the manual test run moves the vertical and horizontal carriages, starts the spindle, and rotates the tool holder. When the tool holder is continuously rotated manually, it is suddenly found that the tool holder is somewhat loose. During the operation of the machine tool, it is not automatically locked. It is judged that the tool holder is the tool holder. System failure, but the “alarm number” is not displayed after a failure occurs in the processing process, so it must be a mechanical failure of the tool rest.
After disassembling the tool holder, the maintenance personnel found that one spring positioning counter pin inside was broken (the CNC electric four-station square tool holder is equipped with 4 spring positioning counter pins) in the process of machining the workpiece When the blank allowance is slightly larger or the hardness is too high, the tool holder rotates to a certain station and the spring positioning is not broken. When the counter pin is stressed, the tool holder can automatically lock the tool. Turning is normal. When the tool holder rotates to a certain station, it breaks. When the force of the spring positioning pin is too large, the tool holder cannot automatically lock the tool and the above fault occurs when turning.
2, Troubleshooting
After a comprehensive inspection by the machine tool maintenance personnel, the electrical control part of the tool rest is normal and it is a mechanical failure after replacement After the broken spring is positioned against the pin, the tool holder is installed and the fault is eliminated.
Causes and solutions for the failure of the CNC tool rest or the constant tool position
The following is a lathe equipped with a DTM system (Ditma CNC system) Take an example to illustrate:
1, the cause of the failure
The lathe occasionally has continuous operation of the tool post during automatic operation Or the phenomenon that a certain tool position does not stop, sometimes it stops and locks after running 2 to 3 tool positions continuously. When continuous operation or a certain tool position does not stop, the “301” alarm (tool post failure) appears on the display screen. The machine tool automatically stops running. When 2 to 3 tool positions are stopped and locked in continuous operation, the alarm number is not displayed. The machine runs automatically. normal.
Because the fault is random and irregular, it is inconvenient for maintenance personnel to check and determine that it is an electrical control fault. After checking that the output voltage of the tool post control system is normal, the relay of the tool post control system is also normal. Finally, remove the protective cover at the top of the tool holder and measure the input voltage of the Hall element signal line one by one. It is found 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 is rotated to a certain position, the wire protection rubber skin is affected by If the two ends of the copper core wire cannot be connected normally, the program control system cannot find the corresponding tool number, and the “301” alarm will appear. When the machine tool is reset and the tool holder is manually rotated to a certain position, the wire protection rubber skin is loosened and both ends of the copper core wire are connected and the tool holder rotates normally and no alarm signal will appear.
2, Troubleshooting
After the maintenance personnel replaced the Hall element connection signal line, the test failure was eliminated. Operating normally.
Summary
Comprehensive analysis of the above two cases of fault finding and troubleshooting process, we can make it clear that CNC machine tool faults not only occur in the electrical part, but also may occur in the mechanical part. 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. The daily maintenance and maintenance should be strengthened during operation and use. If the “alarm number” is not displayed after a fault, it may be a mechanical fault. Checking the mechanical part This will make troubleshooting more accurate and timely for maintenance personnel.
The CNC tool post does not rotate or is stuck
There are five reasons for the failure: (1) The spring is broken. (2) The guide pin of the clutch is broken. (3) The main shaft is bent or broken. (4) The guide pin at the outer chainring is broken. (5) The tool holder is indexed, but the tool holder has rotated through multiple tool positions and cannot be fixed at any tool position.
Spring breakage removal method: replace the spring, be careful not to confuse the two pairs of pins.
The guide pin of the clutch is broken and the solution is to replace the guide pin, and pay attention to the position of the pin hole connecting the clutch and the screw.
Remedy for spindle bending or breakage: Replace the spindle. The replacement method should refer to the spindle description of the corresponding tool holder model. Do not change the size of the spindle at will, otherwise it will seriously affect the service life of the tool holder.
The guide pin at the outer chainring is broken and the solution is to replace the guide pin, and pay attention to the positional relationship between the outer chainring, the nut and the upper cutter body.
Removal method for tool post indexing: Check the static and dynamic parameters of the Hall element, and replace the element if the parameters are abnormal. Replace the CPU board and position multiplier board.
