A preliminary study on non alarm fault diagnosis a

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Preliminary study on non alarm fault diagnosis and inspection technology of machining center

Abstract: non alarm fault inspection of machining center is an important detection means in the use of CNC machine tools, and it is also a key index to measure the development of CNC machine tools. Therefore, the non alarm fault diagnosis and inspection technology of machining center is very important for the actual research and development of CNC machine tools. This paper briefly analyzes the non alarm fault diagnosis and inspection technology of machining center, and puts forward the author's point of view

with the rapid development of electronic technology and interconnection technology, the popularization and application of numerical control machine tools in chemical industry and manufacturing industry are also increasing. Obviously, the improvement of CNC machine tool technology has provided a continuous driving force for the development of China's manufacturing industry, and has also created a positive impact on the national economy. At the same time, due to its complex structure, the sales representatives of many experimental machine sales companies have few opportunities to go to management positions and are highly professional, which increases the difficulty of daily troubleshooting and maintenance. Therefore, in order to better solve the problems of sudden and daily NC machining center faults, this paper discusses the non alarm fault diagnosis and inspection of machining center

1. Brief introduction to alarm fault diagnosis and inspection technology

at present, CNC machine tool centers at home and abroad have automatic alarm function and fault self-test function, that is to say, the operation principle of its control system is: the alarm sensor element is connected with the corresponding fault detection program, and when the machining center fails, it can detect and alarm in time. At the same time, the fault point and type are displayed in detail to help technicians provide maintenance information. Alarm fault display includes software alarm and hardware alarm, that is, computer display prompt alarm and LDE LED alarm. The machining center has no alarm fault, which means that when the fault affects the CNC system, it cannot be displayed normally. When this situation occurs, the troubleshooting and detection work can only rely on experienced technical staff to spend a lot of energy and time on troubleshooting one by one. Therefore, the non alarm fault inspection technology of machining center is very important for the maintenance of CNC machine tools, which needs to be paid enough attention

2. Common faults of CNC machine tools

2.1 random faults

random faults of machining centers refer to faults that happen occasionally in daily working conditions. The occurrence of such faults is random, difficult to analyze and diagnose, and not easy to prevent in advance. The occurrence of such failures is usually related to the following factors: the setting of system parameters, the arrangement of components, the small influence of installation quality fulcrum displacement, equipment quality, subsequent maintenance and operation technology. For example, the failure to maintain the steel parts with rust stains that cause pollution and better service leads to poor contact between resistors, which affects the starting function of the motor

2.2 system fault

machining center system fault is the fault that occurs when the system parameters exceed the set limits and reach the critical conditions. This kind of fault often occurs in the daily operation of CNC machine tools, for example, when the pipeline leakage in the hydraulic system causes the oil level to be lower than the minimum scale line, making the system stop running

3. No alarm fault diagnosis and maintenance of the machining center

when there is a fault in the CNC machining center, the maintenance engineer should calmly think about the observation and investigation of the fault, mainly based on the experience accumulated by the technician in the operation and maintenance, and try to avoid checking immediately. The research of non alarm fault detection technology is very critical to the operation of CNC machine tools. The easily affected factors are pneumatic, power supply voltage, ambient temperature, hydraulic pressure and oil pollution. The specific diagnosis and maintenance are as follows:

3.1 reference point fault maintenance

when the machining center is in operation fault, the reference point should be checked first to check the looseness of the deceleration bump and the fixed state of the deceleration switch. Then check the position of the relative displacement of the machine, the starting position of the return reference point, and finally check the spacing between the reference point and the deceleration switch and the placement position of the reference calculator. When the following problems occur, it is necessary to judge first and then deal with them

(1) when the bump switch is loose, the deceleration system stops running. The workbench should be moved quickly to the mobile terminal instead of continuously decelerating. In addition, when the deceleration switch cannot be turned on and the reference point operation fails, the workbench should be moved quickly to the reference point. The specific maintenance measures are: screw down the deceleration switch and tighten the bump block

(2) when the impact block position moves, it is necessary to detect the moving distance of the position while decelerating. Specific maintenance means: adjust the position of the impact block to make it conform to the zero signal position

(3) when the position of the impact block is very close to the test point or the impact block is too short, it is easy to cause the phenomenon that the search signal is inconsistent with the operation, resulting in the movement of the test point. Specific solutions: adjust the speed of the impact block to make it as close to the reference point as possible

(4) when the encoder or grating ruler and other induction switch parts are damaged, resulting in weak signal or close to no signal, the sliding table will move to exceed the limit, which will be regarded as the reference point operation failure. Specific solutions: only replace relevant parts

3.2 encoder data loss

when the mechanical position data of the serial pulse encoder (excluding special items) is also expected to rise significantly, the following methods can be used for reference:

(1) when the system has the function of returning to the reference point, the technician can return to the reference point manually and press the reset key. (2) When the system does not have the function of reference point, the technician is required to set the reference point program without stopper, and write down the specific position of the reference point. At the same time, when replacing the serial pulse encoder, we should consider the difference of the initial position of the reference point, and debug the new position of the reference point according to the specific data

3.3 automatic tool change fault detection and maintenance

on the premise that the system display has no alarm prompt information, when the program executes the M statement, the tool magazine chain slows down and cannot locate the pin, and the tool change command stops. There are the following common maintenance methods:

(1) the tool sleeve rising contact lever cannot pop up, the contact rod pop-up action is slow, and the tool sleeve falling limit switch is damaged. Specific solutions: first check whether the contact lever of the limit switch operates normally, and then replace the limit switch

(2) when the limit switch of knife pocket rising is damaged, the solution is: first check whether the corresponding equipment is faulty, or directly replace the limit switch

(3) when the induction switch circuit fails, first check the overall circuit, and then check the corresponding induction parts, or replace the inductor

(4) when the tool magazine is overloaded and blocked, the technician should check that the tool loading of the demonstration tool magazine is reasonable, and check whether the oil circuit and hydraulic valve of the hydraulic system are in normal state. (5) When Zhuzhou delivery moves slowly during automatic tool change, first check the pressure value of the pneumatic system to eliminate the failure of rising pressure value

4. Summary

the non alarm inspection technology of machining center is a very key content in the application of CNC machine tools, and it also plays an important role in the development of CNC technology in the future. It is hoped that the points raised in this paper about the non alarm detection technology of machining centers will have a certain reference value for relevant industries, and also hope to cause the manufacturing and chemical industries to pay enough attention to the maintenance of CNC machine tools, so as to ensure the high-quality production of enterprises

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