As an important configuration of CNC lathes, the tool holder plays a vital role in the operation of the machine. Once a fault occurs, it is likely to cause the workpiece to be scrapped or even cause an accident in which the chuck collides with the tool holder. In the fault repair of CNC machine tools, the circuit of the electric control part is complicated, the fault phenomenon is changeable, some fault phenomena are not obvious, the search difficulty is relatively large, and the mechanical part is similar to the ordinary machine tool, and the fault is relatively easy to eliminate. Twinkle System Technology Co Ltd , https://www.pickingbylight.com
In the process of using the CNC lathe, various failures will inevitably occur, so the repair of the fault becomes the most critical factor for the users of the CNC lathe. Among the many failures, the tool holder failure accounts for a large proportion. Since the after-sales service of the machine tool sales company cannot be guaranteed in time, it is understood that some maintenance techniques can quickly determine the fault location, shorten the repair time, and enable the machine tool to operate as soon as possible. Here, it is necessary to analyze the faults encountered in the daily work of the tool holder and the corresponding solutions. Preliminary judgment method of tool post failure condition 1. Listen. 1) When receiving the maintenance request, you should listen carefully to the phenomenon reflected by the operator. If there is any doubt, you should ask clearly to eliminate the problems caused by human factors. 2) Listen to the operation sound of the tool holder in order to observe whether there is abnormal noise.
1. Look. 1) See if the tool holder is running normally. 2) Observe the accuracy of the machined part and the chip marks on the part surface to judge whether the tool holder is locked and whether the repeating positioning is good.
1. Turn. For some faulty tool holders, do not rush to disassemble, you can manually rotate the knife holder. For the four-station tool holder, the worm end has a 6mm hexagon socket. First remove the sealing screw at the section, then use the hex wrench or the screw driver to rotate the worm to make the tool holder index and lock. . Causes and troubleshooting of common faults in the tool holder Motor failure 1) The phase sequence of the three-phase power line is reversed. Remedy: Turn off the power immediately and adjust the phase sequence of the three-phase power supply. 2) The voltage is too low. Remedy: After the power supply voltage is normal, use or increase a stable voltage to provide a regulated power supply. 3) The motor is damaged. Remedy: Replace the motor.
The tool holder does not turn or is stuck 1) The spring breaks. Remedy: Replace the spring, pay attention to the two pairs of pins do not mix. 2) The guide pin of the clutch is broken. Remedy: Replace the guide pin and pay attention to the position of the pin hole connecting the clutch to the screw. 3) The main shaft is bent or broken. Remedy: Replace the spindle. The replacement method should be based on the spindle description of the corresponding tool holder model. Do not change the spindle size at will, otherwise the service life of the tool holder will be seriously affected. 4) The guide pin at the outer end tooth plate is broken. Remedy: Replace the guide pin, pay attention to the positional relationship between the outer end tooth plate, nut and upper body. 5) The tool holder is indexed, but the tool holder is rotated over multiple positions and cannot be fixed at any position. Remedy: Detect the static parameters and dynamic parameters of the Hall element. If the parameters are not normal, replace the components. Replace the CPU board and position board.
The knife holder lock is not tight. 1) The position of the transmitter is not aligned. Remedy: Disassemble the top cover of the tool holder, turn and adjust the position of the transmission plate, so that the Hall element of the tool holder is aligned with the magnetic steel, so that the position is stopped at the exact position. 2) The system lock time is not long enough. Remedy: Adjust the system anti-lock time parameter (new tool post lock time t = 1.2s). 3) The mechanical locking mechanism is faulty. Remedy: Remove the tool holder, adjust the machine, and check if the positioning pin is broken.
The accuracy of the tool holder is not allowed. 1) The tool holder lock is not tight. Remedy: Extend the tool holder locking time. 2) There is garbage at the broken teeth. Remedy: Disassemble the knife holder, remove the garbage, clean the parts, add the cleaning butter to the rotating part, and add the clean machine oil to the end teeth. 3) The pressure of the upper cutter body is deformed by the pressure to make the gear teeth poor. Remedy: Replace the upper body. 4) The tool holder does not stop continuously or the tool holder does not stop at a certain position. Remedy: Check the transmitter wiring for short circuit or open circuit. 5) Hall element and magnet steel height position is not allowed. Remedy: Adjust the relative position of the Hall element to the magnetic steel. Analysis of the tool holder failure example The general process of the NC tool change is: after the tool change motor receives the tool change signal, the tool holder rotates by the worm gear speed reduction, and the tool position signal is sent by the Hall element. The CNC system reuses this signal and target. The values ​​are compared to determine if the tool is in place. After the knife is changed into position, the motor reverses and tightens the tool holder.
Fault 1: A six-knife CNC lathe, all the tool positions can not be found when the tool is changed, the tool holder rotates after several weeks, and the CNC system displays the tool change alarm: the tool change timeout or no signal input.
Fault analysis: For this fault, mechanical faults can still be ruled out due to electrical faults. The electrical causes for this fault are as follows: 1 the magnetic component is off; 2 the six Hall components are all damaged at the same time; 3 the power supply of the Hall component and the open signal line result in no voltage signal output. Among them, the third reason is the most likely. Therefore, the circuit diagram is found, and the power supply line of the electric circuit of the Hall element is inspected by the multimeter. It was found that the 24V supply voltage on the terminal block of the tool post detection line was 0V, and the other lines were normal. Looking along the line with this line as a clue, it was found that the 24V wire lead drawn from the electrical cabinet fell off and remained unresponsive after the connection. Therefore, it should be judged that the line is broken and caused a malfunction.
Solution: After replacing the broken wire with the same specification wire, the fault is eliminated.
Fault 2: A four-blade CNC lathe, the failure of the No. 1 tool position can be found, and other tool positions can be changed normally.
Fault analysis: Since only the No. 1 knife can not find the tool position, the problem of mechanical transmission can be ruled out and it is determined that it is an electrical fault. It may be that there is a problem with the Hall element of the tool location and its surrounding lines, so that the tool position signal cannot be sent to the plc. After checking the multimeter with the multimeter, it is found that the 24V power supply of the No. 1 tool position Hall element is normal, the GND line is normal, and the T1 signal line is normal. Therefore, it can be concluded that the Hall element is damaged and the position signal cannot be emitted.
Solution: After replacing the new Hall element, the fault is solved and the first knife is found normally.
Fault 3: A six-position lathe equipped with the FANUC-0imate system Dalian Machine Tool Plant, the knife selection is normal but cannot be properly locked after the selected tool position is in place. System alarm: Tool change timed out.
Fault analysis: The tool holder is normal, and it is normal, that is, it cannot be locked in reverse. It shows that the worm gear transmission is normal, and it is initially determined to be an electrical circuit problem. On the electrical schematic of the machine tool holder control, it is found that the tool reverse locking in-position signal is controlled by a position switch. (Source: http://) Is the switch the surrounding line? What about the problem? In order to confirm the cause of the failure, open the top cover and side cover of the tool holder, check the circuit with the multimeter with reference to the circuit diagram, and find that there is no open circuit or short circuit on the line. By pressing the tool holder to lock the position switch by hand, observe the ladder diagram. Signal input, thus eliminating electrical wiring problems. It is inferred that the movement of the stopper is not in place and the position micro switch does not operate. So I changed the knife again to observe it, and found that: the block did not move in place. Then tighten the stopper bolts and try to change the knife once. After changing the knife again, the original fault appeared again, and the sleeve of the worm end was found to slip and climb. Is it that the stop of the position switch is not in place when the motor is reversely locked, so the sleeve is axially positioned and the top cover of the tool holder is mounted. As a result, the tool holder is locked properly.
Solution: The axial positioning of the bushing is solved.
Generally, for any fault, firstly, according to the phenomenon, the fault point is judged according to the principle, and each possibility is analyzed, such as a switch, a wire joint, and a screw will be the cause of the fault, referring to the previous operation and maintenance history. Analysis can help narrow down the search range and help improve the efficiency of maintenance.