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Research And Analysis On NC Transformation Of General Machine Tool

Research And Analysis On NC Transformation Of General Machine Tool


Among the currently used machine tool modification solutions are: ordinary lathes converted to hydraulic profiling lathes, cylindrical grinders equipped with automatic measurement devices, horizontal lathes converted to simple broaching machines, and micro file display technology to modify ordinary file machines to improve File machine processing accuracy, ordinary lathe conversion into a slot machine. This article elaborates on this issue.
The transformation of the machine tool is to use the old machine tool whose processing capacity fails to meet the technical requirements or to be idle. For some specific processing requirements, carry out some necessary technical transformation, remove some of the original structure of the machine tool, and add some new transmission or control devices. The modification of existing machine tools is to achieve one or more of the following purposes: to ensure the reasonable use of cutting tools, to centralize processes and steps, shorten the auxiliary time, automate the work cycle, expand the possibility of the process, change the basic process use, and specialize Transformation, improving accuracy, improving the quality and safety of operating machine tools. Machine tool transformation is an effective way for enterprises to improve processing capabilities and change the status of processing. Technical transformation of old machine tools is a method commonly used by manufacturing companies to expand their processing capabilities.

1.Necessity of CNC transformation of machine tools

There are more than 3.2 million machine tools in our country. The technical conditions of these machine tools are severely aging. According to statistics, about 30% of the equipment in the country is more than 16 years old, and nearly 30% of them have a service life of more than 26 years. Mainly rely on scientific and technological progress to transform the machine tool track. In addition, with the advancement of science and technology, production is increasingly dependent on equipment. The company’s output, quality, efficiency, cost, safety, environmental protection and labor mood are all constrained by equipment. It is imperative to modernize the enterprise. . However, according to the data, the annual output of China ’s metal cutting machine tools only accounts for 1/28 of the same type of equipment. For example, it takes 28 years to replace all the machine tools produced every year with the old machine tools. Therefore, the main way to solve the technical progress of equipment in China is Machine tool transformation.

2.Main steps of NC transformation of machine tools

2.1 Determination of the transformation plan

After the feasibility analysis of the transformation is passed, the transformation plan can be determined according to the current process and machine tool conditions, which generally include:

① Combination of mechanical repair and electrical renovation

Generally, machine tools that require electrical modification require mechanical repairs. The integrity of the mechanical properties is the basis for the successful electrical transformation.

② local first and then whole

When determining the transformation steps, the entire electrical part transformation should be divided into several subsystems, such as CNC system, measurement system, spindle, feed system, panel control and high-power parts, etc. After the systems are basically formed, the entire system is interconnected to complete the entire system jobs.

③Select the system according to the conditions of use

According to the external use conditions such as the use environment, temperature, humidity, dust, power, light, and even rodents, this can provide a correct basis for selecting the protective performance, anti-interference performance, self-cooling performance, and air filtration performance of the electrical system. , So that the transformed electrical system has a reliable guarantee of use.

④Determining the scope of transformation

Sometimes the transformation of the electrical system of a CNC machine tool does not necessarily include the entire electrical system of the machine tool, and its transformation range should be determined based on scientific measurement and analysis.

2.2 Technical preparation for transformation

The adequacy of technical preparation before the transformation largely determines whether the transformation can be successful. Technical preparations include:

① Mechanical part preparation

Measurements, calculations, designs, drawings, parts manufacturing, etc. that need to be carried out in order to cope with electrical transformation should be completed in advance.

② Electrical data digestion of old system

Only by fully digesting the electrical data of the old system can we understand the previous design ideas and better complete the connection and conversion of the new and old systems.

③ New system electrical data digestion

The new system has many new functions and new technologies, so you should be familiar with technical information before the transformation, including system principle description, circuit diagram, plc ladder diagram and text, installation and debugging instructions, user manual, programming manual, etc.

④ Conversion design of new and old system interface

For the global transformation, electromechanical conversion interface, operation panel control and configuration, and interconnecting point contacts should be designed. It requires convenient and reasonable operation and maintenance, smooth line direction, few connection points, small strong and weak electrical interference, and appropriate margin. For local reconstruction, the performance matching of new and old systems, voltage polarity and size conversion, installation position, and digital-to-analog conversion need to be considered.

⑤ Determination of commissioning steps

The commissioning work involves mechanical, hydraulic, and electrical. The commissioning steps can be from simple to complex, from small to large, from the outside to the inside, or from local to global, first from subsystems to the whole system.

⑥ Determination of acceptance criteria

The acceptance standard is an assessment of the new system and must be realistic in its formulation.

2.3 Implementation of the transformation

Once the preparations are ready, you can enter the implementation phase of the transformation. The content of the implementation phase is divided into chronological order:

① Comprehensive maintenance of original machine tools

After long-term use of the machine tool, there will be problems in mechanical, hydraulic, lubrication, and cleaning to varying degrees, so comprehensive maintenance must be performed first. Secondly, the geometric accuracy and dimensional accuracy of the machine tool should be measured once and recorded. In this way, it can not only guide the reference work, but also be used for comparison and analysis at the end of the conversion.

② Optimized adjustment of reserved electrical parts

For local modification of the electrical system, maintenance and optimization of the reserved electrical parts should be performed. Such as the replacement of high-power parts, the maintenance of motors, the drying and insulation of transformers, the cleaning of pollution, the cleaning of ventilation and cooling devices, the optimization and adjustment of servo drive devices, the renewal of aging wires and cables, and the tightening of connectors .

③Removal of the original system

The dismantling of the original system must be carried out carefully in accordance with the original drawing, and the drawing shall be marked in time to prevent omission or over-disassembly (in the case of partial renovation). In the process of dismantling, some deficiencies in the new system design will also be found, which should be added and corrected in time.

④ Reasonably arrange the location and wiring of the new system

According to the new system design drawings, the new system configuration is reasonably carried out, including box fixing, panel placement, wiring direction and fixing, adjustment of component positions, sealing and necessary decoration. Should ensure the wiring process specifications, wire diameter is appropriate, correct, reliable and beautiful.

⑤ Commissioning

Commissioning must be carried out in accordance with predetermined steps and requirements. The debugger records at any time to find and solve the problem. During debugging, first test the sensitivity of the safety protection system to prevent personal and equipment accidents; each moving coordinate carriage is at the center of the full stroke; for those that can perform no-load tests, load them first after no-load; if they can simulate the tests, simulate them first and then move them; Can be manual, manual first and then automatic.

2.4 Acceptance work and training

Relevant personnel shall be invited to participate in the acceptance work and shall be carried out according to the established acceptance standards, including:

① Acceptance of machine performance

After mechanical repair and transformation and comprehensive maintenance, the mechanical properties of the machine tool should meet the requirements, and the geometric accuracy should be within the specified range.

② Acceptance of electrical control functions and control accuracy

The functions of the electrical control must be normal, sensitive and reliable. Control accuracy should be checked by standard measuring instruments (such as laser interferometers, coordinate measuring instruments, etc.) to reach the accuracy range. At the same time, it should also be compared with the various functions and accuracy of the machine tool before the transformation to obtain a quantitative index difference.

③ Acceptance of test pieces

The test piece can be used to check the rigidity, force, motion trajectory and associated actions of the machine tool.

④ Acceptance of drawings and documents

After the transformation of the machine tool, the drawings (including schematic diagrams, configuration diagrams, wiring diagrams, ladder diagrams, etc.), data (including various manuals), transformation files (including various records before and after the transformation) should be summarized, organized, Archive. Keeping the data complete, effective and continuous is very important for the stable operation of the device in the future.

⑤ Technical training for operators and programmers


With the application of digital control technology in the mechanical processing industry, CNC machine tools have become the main processing equipment of manufacturing enterprises. The conversion of ordinary machine tools (turning, milling, drilling) into simple CNC machine tools has also become popular. Modification of the machine tool either improves the production efficiency and automation of the machine tool, reduces the labor intensity of the operator, or improves the machining accuracy and surface quality of the machine tool, or expands the processing capacity and process range of the machine tool, all of which are for production. The enterprise has brought considerable economic and social benefits.