Talking about the human fault of CNC machine tools
Due to its high purchase cost and high maintenance cost, CNC machine tools have a large downtime loss. Therefore, reducing the number of faults and downtime is a human error that all users care about the so-called CNC machine tools, which is caused by human factors, not electrical components aging or machinery. Failure caused by natural wear and tear of components. This article is only discussed from the perspective of machine tool users.
Man-made damage or man-made faults exist in the various aspects of the maintenance, repair and transformation of CNC machine tools, and they all have their own different characteristics. The occurrence of man-made faults is subjective and objective. The deformation stress is inversely proportional to the diameter of the spring wire. When the spring is corroded in use, the diameter of the spring wire becomes smaller, and the shear stress of the spring deformation increases, resulting in spring failure.
Affected by non-central loads In the operation of the boiler, the safety valve should periodically discharge the super-pressure steam. After the steam is exhausted, the valve stem is easily deflected, causing the safety valve to leak and the spring to be subjected to a non-central load and being eccentric, so that the safety stress value of the circular spring is lowered.
That is, the safety stress is inversely proportional to the eccentricity of the load, so that the safety valve spring is disabled and the service life is shortened.
Affected by impact load During the operation of the boiler, the safety valve is in a state of frequent beating, and a large impact velocity is generated when the steam is exhausted. At this time, the front ring of the spring first receives the impact load and absorbs more impact energy. The impact load is not transmitted quickly and efficiently to the rear coil. Lead to plastic deformation of the front ring and failure.
In order to prevent corrosion failure of the safety valve, attention should be paid to timely maintenance and repair of the safety valve to keep it in good condition; 2 prohibiting the boiler from running at a high water level, preventing excessive leakage of salt and water when the safety valve is exhausted, causing spring corrosion; 3 boiler water quality To meet the reasons for the 1576 aspect. Subjective reasons such as whether the parties are serious and responsible for the work; objective reasons such as the level of knowledge of the technical level of the person involved.
The following are explained separately.
transport. The transportation of CNC machine tools often comes into question due to human factors. If the machine tool user undertakes the transportation obligation according to the contract, special personnel shall be assigned to supervise the loading and unloading and transportation of the machine tool, especially pay attention to the loading and unloading of the machine tool to avoid scratching and scratching. For newly purchased CNC machine tools, manufacturers should consider handling safety and precision retention, and take measures such as locking and strengthening support for moving parts of machine tools. Because the machine tool user adjusts the water quality standard requirements of the low-pressure boiler in 1996, it prevents the safety valve from carrying impurities to scratch the sealing surface when the steam is exhausted, so that the safety valve leaks and causes the spring to corrode; 4 the bottom of the safety valve discharge pipe should be provided with a drain pipe to prevent cooling. Water is deposited in the safety valve body, causing spring corrosion; 5 Do the dust protection work of the safety valve to prevent the dust from being corroded on the spring for a long time.
When installing the safety valve, it is necessary to ensure the coaxiality and vertical installation of the stem spring and the valve body, reduce the eccentric load of the spring, and increase the safety stress value of the safety valve spring.
Adjust the load reasonably to avoid frequent movement of the safety valve to improve the service life.
Zhang Yinghui Liu Huihang Wang Decheng. Spring manual. Mechanical Industry Press.
Zheng Weicheng. Measures to improve the service life of boiler safety valve springs. Boiler and pressure vessel safety technology. 1995 communication address Xuzhou City, Jiangsu Province, 221008 telephone 0516 program and move the CNC machine tools in use, should also take appropriate locking support and other measures to avoid damage to the machine.
For example, the 8103 double table processing center purchased by our factory was transported to the factory. It was found that the upper cable tank with sheath and the internal cable hydraulic tubing and belt sheath have different degrees of damage. In severe cases, the cable sheath and The internal cables are all cut off. Later, although the machine tool manufacturer replaced all the scratched and scratched parts, it also caused a loss of more than a month of late production. The main reason for this question is that the loading and unloading workers are barbaric in the process of container loading and unloading processing centers. In order to avoid such incidents, the CNC machine tool management installation and commissioning. During the installation and commissioning phase, the user should work hard to cooperate with the manufacturer's commissioning personnel to do the installation and debugging work. Before commissioning, the commissioning personnel should be familiar with all the information provided by the CNC machine tool manufacturer.
Since the CNC machine tools are electromechanical products, the commissioning personnel dispatched by the machine tool manufacturers often have a fine division of labor and electromechanical separation. At this time, the user who participates in the debugging is both a student and a supervisor, and should always be careful not to cause damage to the machine due to human factors.
System. Because the equipment purchased by our factory is the first batch of products that have been put into production after the development of the machine tool, there are many software and hardware for the machine tool. At the time of on-site commissioning, the machine tool builder debuggers, 10; the software is frequently modified and 10 program loaded. During the four months of commissioning, the programmer and machining center were connected in a non-stop state! The communication cable of the 2320 asynchronous communication interface causes the communication interface board of the machine tool to burn out, cannot transmit data, and prolongs the debugging time.
use. Incorrect use, for example, using a machine tool outside the CNC machine tool to allow performance specifications; erroneously changing machine parameters during operation, or even deleting all parameters; or mechanical part of the machine is damaged due to misoperation; or not in accordance with the machine manufacturer's specified operating sequence Open the machine, the time interval is too short, causing damage to the CNC system.
In order to avoid human error during use, the management of the operator should be strengthened. Strictly implement the training and fixed-point fixed machine and fault reporting system, and adhere to the principle of accidents. In terms of distribution, it should reflect the high-quality factors of high-tech equipment operators and properly tilt.
In addition, the ideological education of operators should be strengthened to cultivate their serious work style.
417427437 and other alarm information. When the operator is asked about the situation before and after the failure, it is known that the person is a malfunction.
According to the operator, a 21-axis negative overtravel alarm occurs during the use of the machine. This is a simple question. For the software limit alarm, first move the axis hand wheel in the positive direction more than 201, use only the 31 key to clear the alarm displayed on the 081, and then return the reference to the reference point mode. Just click. If in the handwheel mode, the handwheel cannot be moved in the positive direction by hand, the hardware overtravel must be pressed by the overtravel release button on the machine operation panel, and the hand wheel will move the axial positive direction more than 2, Then, set the two parameters to the parameters. 701 and him. Write the value of 705, and then modify the parameter 701=99999999705=99999999. After referencing each servo axis back to the reference point in the reference point return mode, then alarm 701, and press only the 3 button and the button to clear. Because of this operation, the machine is turned on, and the memory of the machine parameter program is cleared. After using more than a day, manually input machine parameters, parameter user macro program part processing program, etc., the machine side returned to normal.
maintenance. If you do not pay attention to maintenance during maintenance, it is easy to cause human failure. For example, the filter screen for filtering dust of the electrical control cabinet is not cleaned in time, so that the heat dissipation of the electrical components in the cabinet is not good, the temperature rises too high, and the fault is easy to occur; or the cleaning method is incorrect, and the dust in the electrical box is cleaned by the unfiltered compressed air; Cleaning the workbench with compressed air causes chipping and splashing onto the electrical components, causing a short circuit. The addition or replacement of the liquid deterioration failure will cause the machine to ask.
Should adhere to the daily inspection, according to the requirements of the equipment manufacturer, strictly carry out the annual inspection and annual inspection of the annual inspection, and find out the problem in a timely manner. The deactivated CNC equipment should be turned on for a period of time, expel the moisture in the electrical box and charge the backup rechargeable battery to avoid malfunction of the CNC system. It can also fully lubricate the lubrication parts of the equipment to avoid rusting of the parts and lubrication of the pipeline. Blocked for a long time.
For example, the Taiwan 0616 lathe, which was rebuilt with a single-board machine in the early 1980s, was used for roughing of crankshaft forgings. The machine tool is used before the Spring Festival, and it will be used after shutdown. After the Spring Festival, the work is turned on, and the 2-axis stepper motor is out of step. The power amplifier circuit is measured normally, and the direction control signal and the pulse control signal output by the interface circuit are normal. Replacement, shaft stepper motor test, still out of step. Open the stepper motor current limiting resistor box cover and find that there are many iron shoulders inside, which causes the two-way stepping motor current limiting resistor to short-circuit between the two phases. After the iron filings are cleaned, the machine tool returns to normal.
service. During the maintenance process, human error caused by ignorance, self-confidence and carelessness, and even the widening of the fault range sometimes occur. This is related to the technical quality of the maintenance personnel and to the personal work style. If some maintenance personnel repair the CNC machine tool, in the absence of technical information, the wires under the disassembly are not marked, and the corresponding wiring relationship between the wires and the terminals has been recorded with confidence. However, if the fault is analyzed, the working principle of the AC stabilized power supply and the faults of the Lin Liwu and Lei class work and maintenance techniques.
At present, there are still large fluctuations in the supply voltage in some places in China. The peak voltage during power consumption is less than 180. When the load is minimum, the voltage is as high as 240, and the fluctuation range is between 2 and +; while the voltage fluctuation range of small grids in rural areas is larger. For units with a large number of imported precision and precious equipment, voltage fluctuations will cause great harm. In a laboratory experiment, the voltage suddenly increased. Almost all the equipment that was turned on, including the US import, cost $3,600, and the experimental teaching and research project was interrupted for a long time, and the consequences were extremely serious. In another laboratory equipped with an AC regulated power supply, there is no equipment damage except for the AC regulated power supply alarm when the voltage is abnormal. However, in addition to the voltage regulation, the AC stabilized power supply also has a protective effect on the load.
The AC stabilized power supply is a magnetic amplifier type, that is, the 614 series thyristor phase shift voltage regulator type autotransformer with servo motor is more common. There are also inductive regulator-type magnetic saturation and regulated transformers. Several of them have been basically eliminated due to performance indicators and other reasons, replaced by the rapid development of AC purification power supply in recent years.
The basic principle of the power supply is similar to that of the thyristor phase shift voltage regulator. The following is an example of the Yaguang brand 耵 12 series AC purification power supply produced by Jiangsu Huaiyin Instrument Factory. The power supply adopts the advanced sinusoidal energy distribution technology power filter technology comprehensive design, which integrates the voltage regulation and anti-interference functions, has the advantages of high reliability, high efficiency, wide voltage regulation range and strong anti-interference ability.
The working principle controls the trigger pulse width of the triac by sampling and amplifying the AC output voltage, and controls the conduction angle of the thyristor, thereby controlling the AC output voltage and realizing the AC regulated output. The AC net repair time is prolonged. The memory of the original wiring relationship after the fault is removed has long been blurred. In light, the time is delayed in order to re-determine the wiring relationship, and the device is damaged due to wiring errors. For another example, the fuse of the power fuse is often encountered. It should be found that the cause of the fuse is replaced by a new test run, but some maintenance personnel do not check the cause of the blow, and rashly replace it with a new fuse. The scope of the problem has expanded.
Due to the high price and high technical content of CNC machine tools, the overall quality of maintenance personnel is high. It is necessary to strengthen the technical training for maintenance personnel, establish an effective mechanism to mobilize the maintenance of CNC machine tool maintenance personnel to improve the enthusiasm of work, and reduce or eliminate human error.
For example, the connecting rod plane uses Toshiba, 40 calendar 3 plus expansion, 20 programmable controller control. The fault phenomenon is that after the power is turned on, the 0 scale 1 watt 0 finger light and only 0 0 finger light are on. Upon inquiry to the repairing electrician, it is known that the initial fault is not functional, and the cause of the fault is very simple, only a limit switch fails. Because the machine has been broken before, only 20 modules, so the electrician did not understand the trapezoid and check the electromagnetic valve of the peripheral switching device, etc., self-righteous, 40 questions, blindly random test. As a result, after the socket was installed with the universal module only 0 module, only the 0-foot light was on.
Check the trapezoid with the programmer and find that the program has changed. After the modification, the boot is normal.
Transformation. There are basically two cases of machine tool transformation, which is the numerical control transformation of ordinary machine tools, and it is a system update of the system aging CNC machine tools. To some extent, the transformation of the machine tool is a process of perfect function or redesign. It may be due to poor consideration of the transformation plan or improper modification measures, and there is a phenomenon of high failure rate in the early stage of the new machine tool. Due to the large amount of tasks for machine tool transformation, there are many construction workers and it is more prone to human failure.
In short, man-made faults can not be ignored in the life cycle of CNC machine tools, and effective measures should be taken to reduce or eliminate them.
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