China Shenzhen Perfect Precision Product Co., Ltd. company news

CNC machine tool faults can be divided into electrical faults and mechanical faults according to the location of occurrence. Electrical faults generally occur in the control parts such as system devices, servo drive units and machine tool appliances. Electrical faults are generally caused by factors such as the decline of quality factors of electrical components, loose welding of components, poor contact or damage of connectors and connectors.   These faults sometimes occur, such as the large leakage current of an electronic component, After working for a period of time, its leakage current increases with the increase of ambient temperature, which leads to abnormal operation of components and affects the normal operation of the corresponding circuit. When the ambient temperature decreases, the fault disappears again. This kind of fault is difficult to find by visual inspection. Generally, the working voltage should be checked with the help of measuring tools. Current or measure boxing for analysis. Mechanical faults generally occur in the mechanical moving parts.   The mechanical faults of CNC machine tools can be divided into functional faults, action faults, structural faults and applicability faults. Functional faults mainly refer to the faults of workpiece processing accuracy. These faults can be found, for example, the processing accuracy is unstable, the error is large, etc. action faults refer to various action faults of machine tools, which can be expressed as the spindle does not rotate, The workpiece cannot be added.   The positioning accuracy of the tool rest is low, and the hydraulic speed change is not flexible. The structural faults can be manifested as the heating of the spindle, the noise of the spindle box, the abnormal noise of the mechanical transmission, and the cutting vibration. The serviceable faults mainly refer to the faults caused by improper use and operation, such as the damage of the machine parts caused by excessive, and the mechanical faults can generally be prevented through maintenance and careful adjustment.

The non-destructive testing of fault maintenance of CNC machine tools is a special technology to detect mechanical parts (metal and non-metal) to find surface and internal defects without destroying or changing the inspected object by using the characteristics of a physical property that changes due to the existence of defects.   Nondestructive testing technology is not only widely used in product quality management, but also of great significance to improve the operation reliability of equipment. Therefore, it has become an important part of mechanical fault diagnosis.   It is an important means to explore the root causes and mechanisms of faults, predict hidden dangers, and also a prerequisite for preventive maintenance. There are many methods of nondestructive testing, including ultrasonic testing, radiographic testing, magnetic particle testing, penetrant testing, eddy current testing and acoustic emission testing.

Temperature is closely related to the operating state of mechanical equipment. 1. On the one hand, common failure forms such as abnormal damage of mechanical parts and blockage of pipes will cause the temperature of corresponding parts to rise. Therefore, overflow is a characteristic parameter of mechanical failure. 2. On the other hand, the performance of mechanical parts is closely related to temperature. If the temperature is too high, the performance of parts will be reduced, and even parts will be burned. Therefore, temperature is also an important factor causing mechanical equipment failure. Therefore, temperature monitoring plays an important role in fault diagnosis of mechanical equipment. The so-called temperature monitoring refers to the use of various temperature measuring instruments to measure the temperature rise of the mechanical device, and compare it with the temperature of the mechanical device during normal operation, so as to diagnose the faulty parts and fault degree.   In the fault diagnosis and monitoring of mechanical equipment, temperature measurement methods can be divided into contact temperature measurement and non-contact temperature measurement. 1. Contact temperature measurement has the characteristics of fast, correct and convenient, so it has been widely used in various industrial fields. However, it can not meet the temperature measurement requirements of some special occasions, such as temperature monitoring at the junction of high-voltage transmission lines, temperature monitoring of steel-making blast furnaces, etc. For these occasions, non-contact temperature measurement must be adopted. 2. The non-contact temperature measurement method has the advantages of not destroying the temperature field of the measured object and measuring the temperature of moving parts, but it can only measure the surface temperature of the system, not the internal temperature.

The machine tool body includes the main moving parts, feed moving parts, executive parts, base, column, tool rest, workbench and other basic parts of the machine tool. CNC machine tool is a kind of high-precision, high-efficiency and highly automated machine tool, which requires that the mechanical structure of the machine tool should have high precision and stiffness, good accuracy retention, and high motion accuracy of main motion and feed motion parts. The feed transmission system of machine tools generally adopts precision ball screws, precision rolling guide rail pairs and sliding guide rail pairs with good friction characteristics to ensure the sensitivity and accuracy of the feed system. It can be said that the machine tool body structure with high precision and high stiffness is the foundation to ensure the efficient, high precision and highly automated machining of CNC machine tools.

CNC machine tools are evolved from ordinary machine tools. Compared with ordinary machine tools, CNC machine tools have the characteristics of strong adaptability. Adaptability refers to the adaptability of CNC machine tools that changes with the change of production objects. As the market demand for products gradually tends to diversify, the realization of single piece and small batch production automation has become a top priority for the manufacturing industry. When the product changes, for CNC machine tools, only changing the input program of CNC machine tools can meet the production needs of new products, without changing the hardware of mechanical part and control part, and the production process is completed automatically. Therefore, the use of CNC machine tools has short preparation period and strong flexibility, which provides convenient conditions for multi variety and small batch production and the development of new products.

According to the formation speed, there are gradual faults, sharp faults and sudden faults. 1. Gradual failure refers to the gradual deterioration of the functional indicators of parts and components of CNC machine tools or CNC processing equipment, but they can continue to operate. 2. Sharp failure refers to the sharp deterioration of the functions of parts and components of CNC machine tools or CNC processing equipment, which cannot continue. 3. Sudden failure refers to unlicensed. Unpredictable failure. In addition to the above classification, faults can be divided into early faults, accidental faults and wear and tear faults in terms of time. From the perspective of use, faults can be divided into use faults and essential faults. Faults can also be divided into catastrophic, fatal, severe and mild faults in terms of severity. According to the process of failure, it can be divided into sudden failure and gradual failure. According to the frequency of occurrence, there are sporadic faults and multiple faults. According to the consequences, there are general faults, serious faults and malignant faults.

High precision: the CNC machine tool works automatically according to the predetermined program, and the working process generally does not need manual intervention, which eliminates the error caused by human factors caused by the operator. When designing and manufacturing equipment, many measures are usually taken to make CNC machine tools achieve high accuracy. At present, the pulse equivalent of the numerical control device can reach 0.01 -0.0001mm, and higher accuracy can be obtained by real-time detection error correction or compensation. High efficiency: because the CNC machine tool can adopt a large cutting amount, it effectively reduces the cutting hours in processing: the CNC machine tool also has the functions of automatic speed change, automatic tool change and other auxiliary operation automation, and does not need the inspection and measurement between processes, which greatly shortens the auxiliary time; For multi-functional machining centers, almost all parts can be processed after one clamping, which can not only reduce the clamping error, but also reduce the turnover time of semi-finished products. Therefore, compared with ordinary machine tools, the production efficiency of CNC machine tools is many times higher. For the processing of complex surfaces, the production efficiency can be increased several times, or even dozens of times.

1. Good flexibility The control function of hard wired NC machine tool is realized by hardware circuit. If you want to change the processing control function of the system, you must rewire. CNC machine tools can flexibly change or increase the functions of the CNC system through the programming of software, which has great flexibility. 2. Powerful function CNC machine tools make use of the high computing and processing ability of computers to realize many complex numerical control functions, such as quadratic curve interpolation, multi axis linkage, fixed cycle machining, coordinate offset, graphic display, tool compensation, etc., so that the tool can realize any trajectory in three-dimensional space and complete the machining process of complex surfaces. Hard wired NC device can only carry out simple straight-line and arc interpolation calculation to complete the processing of straight-line and arc. 3. Good versatility CNC machine tools can be programmed with different software to meet the different processing requirements of various machine tools. In this way, the same CNC device can be used to meet the requirements of various CNC machine tools, reflecting strong versatility. However, due to different functions and types of hard wired NC machine tools, NC devices are different and cannot be used in general. 4. High reliability The part program of hard wired NC machine tool is read and processed in sections in the processing process. Frequent startup of photoelectric reader may cause faults and cause part program errors, which is the main reason for the low reliability of hard wired NC device. CNC machine tools can use tape, floppy disk and other input devices to input the part processing program into the memory at one time, which avoids the errors caused by frequently opening the photoelectric reader in the processing process and improves the reliability. CNC machine tools are also easy to set up various diagnostic programs, which can carry out fault pre inspection and automatic search, facilitate maintenance and reduce downtime. 5. Easy to realize electromechanical integration CNC machine tool adopts large-scale integrated circuit and advanced printing and typesetting technology. The whole control system can be formed by using several printed circuit boards, which greatly reduces the size of its hardware structure, and can be combined with the machine tool to reduce the floor area and realize electromechanical integration.  

As enterprises put forward higher requirements for machining accuracy and productivity, the principle of process concentration is being adopted, and various types of machining center machine tools have emerged. The machining center not only has all the functions of general CNC machine tools, but also has tool magazine and automatic tool change device, breaking the traditional concept that only oneortwo processes can be completed on a CNC machine tool. Taking the milling machining center as an example, a large capacity tool magazine (generally able to accommodate 20-120 various tools) and an automatic tool pressing device are added to the CNC milling machine. After the workpiece is clamped at one time, most of the machined surfaces of the parts can be processed by multiple processes such as milling, boring, drilling, reaming, dumpling hole and tapping. In recent years, the pentahedral machining center machine tool can complete the machining of all surfaces of the box type except the mounting surface in one clamping. Turning machining center has also been widely used. It can complete all machining processes of rotating parts (including turning internal and external surfaces, milling planes, milling grooves, drilling and tapping, etc.) in one clamping. The machining center machine tool can effectively avoid the positioning error caused by multiple clamping, and reduce the number and floor area of the machine tool, which greatly improves the productivity and processing automation. The method of classification according to process use can play an important guiding role in the continuous development of new products of CNC machine tools.

According to the classification of process use, the most commonly used CNC machine tools are divided into CNC drilling machines, CNC lathes, CNC milling machines, CNC boring machines, CNC grinding machines, CNC gear processing machines, CNC engraving machines and other metal cutting machines. Although these machine tools have great differences in processing technology and specific control methods, they are applicable to the processing of single piece, small batch and multi variety parts, with good consistency of processing size, high productivity and automatic procedures. In addition to numerical control machine tools for metal cutting, numerical control technology is also widely used in non-metal cutting machine tools such as punch, press, bending machine, bending machine, wire cutting machine, welding machine, flame cutting machine, plasma cutting machine, laser cutting machine and high-pressure water cutting machine. In recent years, numerical control technology is also widely used in non processing equipment, among which the most common are automatic assembly machine, multi coordinate measuring machine, automatic plotter, numerical control printing and dyeing machine, rapid prototyping machine and industrial robot.