Analysis on the safety and quality of machine tool

Abstract: This paper expounds the potential safety hazards of machine tool products and the implementation of national supervision and random inspection, product certification, safety certification and other systems and measures, which promote the implementation of machine tool safety standards and effectively improve the safety level of machine tool products

I. importance of machine tool industry

equipment manufacturing industry is the basic industry of the national economy and the cornerstone of supporting the development of the whole industry and the national economy. Machine tool is a machine for manufacturing machines, is a machine tool, as the basic equipment of equipment manufacturing industry, is the foundation of the foundation. With the progress of science and technology, the technical level of machine tools is also developing at a high speed, especially the application of numerical control technology and numerical control machine tools, which has made fundamental changes in the machinery manufacturing industry. Numerical control technology is the basis of automatic, flexible and integrated production in mechanical manufacturing industry, and it is an important means to reduce labor intensity and improve labor productivity. The level and ownership of CNC machine tools is an important symbol to measure the level of a country's industrial modernization, and plays a decisive role in the development of the national economy and the enhancement of national defense strength. Therefore, the quality and safety of machine tool products will directly affect the development of national economy

II. Potential safety hazards and analysis of machine tool products

machine tools are mechanical equipment integrating machinery, electricity, fluid and gas. They have many risk factors and cause great damage. Through product inspection over the years, we found the following hidden dangers and problems in machine tool products:

hidden danger 1: workpieces and knives fly out of danger, hidden killing machine tools are high-speed machines. If the rotation speed of the machine tool spindle is low, it will rotate hundreds of revolutions per minute, and if it is high, it will rotate tens of thousands to hundreds of thousands of revolutions per minute. The workpiece and/or cutter rotating at high speed may fly out, which may cause personal injury or even death. Specifically, first, the clamping device of the workpiece or tool is not firmly clamped, causing the workpiece or tool to fly out; Second, there is no protective device or the protective device does not meet the requirements, and the flying workpiece or cutter cannot be protected; Third, there is a lack of necessary warning content for users in products or technical documents

hidden danger 2: the product has the risk of electric shock

electric shock is divided into direct electric shock and indirect electric shock: the electrified body whose human body directly contacts the dangerous voltage is direct electric shock; The electrified body that is not electrified when touched by human body and is electrified due to insulation failure of electrical parts is indirect electric shock. The direct electric shock danger of the product is usually that the live terminal of the power supply is not protected, that is, the live terminal is exposed, and the user is very likely to have an electric shock accident in use or maintenance; The indirect electric shock hazard of the product is usually the incomplete electrical grounding system of the machine tool and the lack of protective grounding wire. The protective grounding wire is called 'lifeline', which is very important to the operator. Once the insulation of electrical components fails and leakage occurs, it can effectively protect the safety of personnel, and its importance is self-evident. Hidden danger 3: there are safety hidden dangers in the emergency stop operating parts and power switches. The emergency stop operating parts are extremely important for machine tool products. They are electrical devices specially set up to reduce casualties or equipment damage in the event of an accident of the machine tool. The standard requires that the emergency stop device has a specific purpose, no additional danger, easy operation, self-locking mechanism, and the color is special red. The product has no emergency stop device or the emergency stop device does not meet the standard requirements. In case of emergency or accident, it cannot prevent personnel from being injured or equipment from being damaged. At present, some enterprises' products do not install emergency stop devices or the emergency stop devices do not meet the standard requirements

the power switch is an important device connecting the machine tool and the external power supply. The power switch on the machine tool is different from the general power switch. In addition to the capacity (including rated voltage, current, short-circuit current, etc.) to meet the use requirements, it is also required to play a good role in protecting the safety of machine tool equipment and personnel. The standard stipulates that "the power switch should provide a locking mechanism in the disconnected position" is this purpose. In order to reduce costs, some enterprises often use the power switch without locking mechanism in the off position, leaving hidden dangers for machine tools

hidden danger 4: static danger cannot be ignored

static danger mainly refers to the harm of the structure and shape of exposed parts of the product to people. For example, sharp edges, corners and burrs of exposed parts may cause scratches to people. Sharp edges, corners and burrs on products not only give people the impression of "rough products", but also may cause different degrees of scratches or stabbing to personnel (such as operators). For example, the periphery of the workbench is as sharp as a knife edge. Once the operator doesn't pay attention to it, he will be scratched. Another example is the chip baffle near the operator, with sharp corners everywhere, which may be scratched at any time

hidden danger 5: the product operation manual is not standardized

the product operation manual is an important part of the product and a guiding document to guide users to operate the machine tool correctly and safely. However, there are many problems in the product manual of machine tools, mainly manifested in: first, the lack of safety precautions or the incomplete content of safety precautions, which can not guide users to use safely, and bring hidden dangers to users. For example, the mobile workbench with rapid positioning has the risk of collision with personnel, which is an unavoidable medium risk in the structural design. In addition to adding permanent warning signs near the dangerous parts, there must be similar text warnings in the product manual; Second, the content in the product instruction manual is inconsistent with the product, causing inconvenience to users for correct use and maintenance. If the circuit diagram of the product is inconsistent with the physical object, once the machine tool breaks down and needs maintenance, the user will have no way to deal with it, so he has to resort to the manufacturer, which undoubtedly brings inconvenience to the user; Third, there is no enterprise contact information or legal unit of measurement, which is not responsible for users

hidden danger 6: the product warning signs are incomplete

the warning signs are also an important part of the product. Their purpose is to enable users to operate the machine tool correctly and safely. Attaching the warning signs to the products can more intuitively remind users from time to time. At present, some enterprises' products have the problem of incomplete warning signs, especially the lack of safety tips for users, resulting in potential safety hazards

III. analysis of quality changes in machine tool industry in recent years

in order to improve the quality and safety of machine tool products and ensure the implementation of safety standards, the state has issued many systems and measures, such as national supervision and random inspection, export quality licensing system, product certification and safety certification. Through these systems, American researchers recently announced and implemented measures that have played an important role in standardizing the quality behavior of enterprises, implementing product quality and safety standards, improving the overall level of product quality in China, and promoting China's economic construction and social development

first, the implementation of these systems has standardized the quality behavior of enterprises and urged enterprises to strictly implement relevant national and industrial standards

before the implementation of the spot check system, the quality behavior of enterprises mainly depended on the self-discipline of enterprises. In the era of planned economy, it was possible to rely on the self-discipline of enterprises. However, with the development of reform and opening up and market economy, coupled with the increasingly fierce market competition, driven by economic interests, it is obviously not enough for enterprises to rely solely on the self-discipline of enterprises to control product quality. It is necessary to carry out national supervision and spot check, It is very necessary for the government to regulate and control the quality behavior of enterprises. Through practical work, we deeply realize that the implementation of the spot check system plays a very important role in standardizing the quality behavior of enterprises. The national supervision and random inspection system has a considerable deterrent effect on enterprises. If the products of enterprises fail to pass the random inspection, it will have a serious impact on the quality reputation of enterprises, affect the sales of enterprises, and even affect the survival and development of enterprises. With certain economic punishment means, enterprises realize that in order to survive and develop, they must improve product quality. Of course, the spot check system is one of the external driving forces for enterprises to improve product quality. Coupled with the requirements of users for enterprise quality, enterprises must take the road of improving product quality under various joint forces. For example, a machine tool manufacturing enterprise, one of the backbone enterprises in the domestic machine tool industry, failed in the national supervision and random inspection of CNC machine tools in 2000. After the announcement in the industry, it had a great impact on the sales of its products, and the local technical supervision department imposed a penalty of more than 100000 yuan. This matter touched the enterprise a lot, which made the enterprise pay attention to product quality fundamentally. In the subsequent national supervision and random inspection (follow-up random inspection) in 2002 and 2003, all products were qualified

secondly, the implementation of these systems has improved the overall quality level of machine tool products. "Spot check a product and rectify an industry". Through spot check, we can help and promote enterprises to improve product quality and improve the overall quality level of our products, which is the purpose of the state to implement these systems. Through the spot check of machine tool products, it really reflects that the implementation of the spot check system has indeed played a role in improving the overall quality level of machine tool products

sawing machine is a kind of machine tool. As a necessary equipment for sawing and cutting metal materials, it is one of the machine tool products with a large number and a wide range. In 1998, the original Announcement No. 1 of the State Bureau of technical supervision published the catalogue of the first batch of mechanical products with safety certification in China, among which sawing machine is listed. Such products are naturally the key products of national supervision and random inspection. Surprisingly, the pass rate of the first spot check in the fourth quarter of 1998 was only 16.7%. Then in the second quarter of 2001, the third quarter of 2002, the second quarter of 2004 and the second quarter of 2007, spot checks were carried out on the sawing machine, and the qualified rates were 3 corresponding to the replacement of 78 imported brands, 6.8%, 50.0%, 60.0% and 65.4% respectively. It can be seen that the passing rate of spot check is gradually rising, and the overall quality level of sawing machine products is gradually improving

CNC system is an important independent component of CNC machine tools. Numerical control machine tool is an optical electromechanical integrated product integrating mechanical manufacturing, computing, optoelectronics, sensing and servo drive technology. With the development of national economy, CNC machine tools have become the main force of modern manufacturing, and the core of CNC machine tools is CNC system, which is of great significance to promote the development of modern manufacturing, improve labor productivity, improve machining accuracy and reduce production costs. The unqualified CNC system, especially the unqualified electromagnetic compatibility of products, will have a serious impact on the reliability of machine tools. In recent years, the random inspection of CNC system is as follows: the sampling qualification rate in 1998 was 38.4%; In 1999, the qualified rate of sampling was 25%; The qualified rate of sampling in 2000 was 41.7%; The qualified rate of sampling in 2001 was 88.9%; The qualified rate of sampling in 2003 was 78.6%; The sampling qualification rate in 2004 was 80.0%; In 2005, the sampling qualification rate was 80.0%; In 2006 and 2007, there was no spot check on the CNC system. It can be seen that through random inspection, the qualification rate of the CNC system has increased from the initial 38.4% and stabilized at about 80.0% now, and the overall quality level of the CNC system has been greatly improved

finally, the implementation of these systems is conducive to the governance and rectification of regional quality problems in the industry, and plays a positive role in improving regional quality problems

the country has always attached great importance to the quality of machine tool products. Next, the technicians of our company will introduce the characteristics and level of digital display electronic tensile testing machine