The imported horizontal machining center is an important equipment for gearbox housing processing. During long-term operation of the equipment, a position feedback system alarm occurred, causing the equipment to be paralyzed. Based on this, a set of rapid maintenance procedures have been summarized to ensure that the production schedule is not delayed.
1 Preface
The horizontal machining center imported by the company is a four-axis horizontal linkage machining center, mainly used for boring and end face processing of gearboxes, with machining accuracy of up to ‘to 0.001 mm. The high precision and stability of the equipment determine the processing quality of the gearbox. The CNC system of this imported horizontal machining center is Mazatrol Fusion 320, and the hardware and software are different from the CNC systems of other machine tool manufacturers, so the maintenance is relatively difficult. Once the equipment generates a loss of home position alarm, it will no longer be able to continue processing and the equipment will be in a paralyzed state, which will cause the gearbox assembly to stagnate and a delay in product delivery time, thereby affecting the business of the company. reputation. It is urgent to resolve this issue through independent research and quickly restore the equipment to normal operation. The following summarizes a set of quick repair procedures for this defect from the analysis of the cause of the defect, the defect solution ideas and the solution process.[1]。
2 Analysis of the causes of failure
The imported horizontal machining center was stopped and started after 8 days. The machine tool screen displayed alarm No. 010 indicating that the original position of the X axis was lost. At the same time, the X axis drive amplifier repeatedly displayed alarm No. 21. -01. The machine tool cannot perform any action and is in a paralyzed state. When this fault occurs for the first time, the maintenance personnel do not have enough experience to solve it immediately, thereby delaying the production progress of the equipment. The company will face a semi-production state and the product delivery time will be delayed.
Alarm No. 21-01 is displayed cyclically on the power amplifier. The appearance of such an alarm indicates that the reference point data is lost. Since the position measurement of the machine tool uses a fully closed-loop measurement system, the original sensing device must be a HEIDENHAIN magnetic array, so there is no need to consider the problem of a motor encoder. According to the analysis of the diagram, the fault may occur due to the following reasons.
1) Before stopping the X-axis servo motor data, the battery voltage is low, resulting in the loss of the X-axis original position data. The axis feedback signal wiring X is shown in Figure 1.
2) Return to origin of the proximity detector or failure of the connection wire.
3) The reading head and ruler body are contaminated and worn.
4) The wire from the read head to the signal acquisition conversion module has a break point; the wire from the signal acquisition conversion module to the servo motor has a break point.
5) The internal driver circuit board is defective and the original data is lost and cannot be saved.[2]。
Figure 1 X-Axis Feedback Wiring
3 Troubleshooting
3.1 Troubleshooting Ideas
According to the possible causes of failure above, you can test and eliminate them one by one, from simple to difficult, to find the real cause of failure.[3]。
1) Check the voltage of the X-axis drive battery.
2) The return-to-origin proximity sensor fault occurs when the alarm occurs during the return-to-origin state. Check whether the state of the home return proximity switch is abnormal. If the X axis cannot detect this signal from the proximity switch when returning to origin, the ‘origin.
3) Protect the X axis magnetic scale detection function, that is, change the fully closed loop to half closed loop. Once this step is completed, it is possible to determine whether the magnetic grid, signal acquisition module, servo motor and associated connection wires are intact. If the alarm disappears after shielding, it means that there is a problem with at least one of the above components. If the site is in a hurry to produce, a semi-closed loop can also meet production needs, but of course the origin must be reset. Perform the following steps when post-processing tasks are not busy.
4) After reducing the extent of the fault, measure whether there is an open circuit or short circuit in the affected connection wires.
5) If the wires are intact, use the exchange method to determine the defective components in the magnetic scale, signal acquisition module and servo motor.
3.2 Troubleshooting process
1) Remove the X axis drive battery with the machine turned on, use a multimeter to measure the voltage with the DC block and observe whether the voltage is 3.6V. If it is less than 3.6V , replace it in time.
2) Check the proximity switch back to home. First adjust and tighten the proximity switch. Then place the iron piece near the reading head of the proximity sensor and observe if the rear LED indicator changes from dark to light. If it does not light up, first measure whether the wire connection is intact before replacing the proximity switch.
3) Protect the magnetic grid measuring system and reset the origin of the X axis. The steps are as follows. ①Enter the password. Enter the password 1131 in the blank space in the lower right corner of the screen. Be careful when entering the password, do not enter it incorrectly, then press the INPUT button after confirming that it is correct (the SV settings bar will only display when the password is entered). ② Change settings. Edit the N10 parameter, enter the parameter interface and find the parameter bar with the prefix N, find the N10 parameter and change the original value from 5 to 8. Edit the SV7 parameter, enter the N10 parameter parameters, go to the SV parameter bar, find the SV7 parameter and change the original value from 0 to 1. Change the SV17 parameter, find the SV17 parameter and replace the original value from 8 to 0. Change parameter N19, find parameter SV19 and change the original value from 32 to 1000. Change parameter N25, find parameter SV25 and change the original value 82C6 to 22C6. After setting the parameters, save the parameters and restart the machine tool. ③The working principle of the machine tool returning to the origin. Whether it is a magnetic gate or a motor encoder, their return-to-zero signals are sent by the return-to-zero proximity detector. The encoder gate signal is 3mm once (internal parameter N10). When the switching signal is 1, the gate signal should be detected once. The machine tool continues to operate. Once the switching signal becomes 0, the machine tool continues to work. run to the next gate. The distance of the gate signal, here is the electrical origin (generally the OFF point is 25% to 75% of the gate spacing). The mechanical origin is the so-called tool change point value. It is obtained by adding the value of parameter N11 to the electrical origin. ④Execute X/Y axis zero return. Start the equipment and perform the X and Y axis return to origin actions. ⑤ Adjust the tool position. After adjusting the physical tool change position and returning the X and Y axes to the origin, manually install two sets of three-piece tools on the spindle and arm of the tool change robot. After installation, perform the manual tool change step. The manipulator rotates to grip the knife on the spindle, and the X axis is manually started until the three-piece assembly is assembled and the current value of the X axis is recorded. ⑥Adjust the proximity switch to zero feedback. If the recorded value is significantly different, you can adjust the zero feedback proximity switch or read head position and set it within 1mm of the current original position. ⑦Set the parameters. Set the X-axis tool change position parameter N11. Add the measured value of the X-axis to the parameter N11 (add or subtract the measured value to the original value). ⑧Debugging. Once the X axis origin is set, save the settings and restart the device. After the equipment is turned on, perform the zero return operation of each axis, and then perform the tool change procedure to check whether the tool change is smooth. If there is any abnormal noise or blockage, you need to repeat steps ⑤~⑦.
4 Conclusion
At present, the company has several imported horizontal CNC machining centers of this series. When a servo alarm occurs when the origin of the motion axis is lost, this method can be directly applied to resolve the fault, which greatly improves the maintenance efficiency and reduces the maintenance time rate. ‘stop. of machine tools. Summarizing and summarizing the usual maintenance process will often yield unexpected results.
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