Research on machining technology of CNC machine tool for irregular parts

Research on machining technology of CNC machine tool for irregular parts

Due to the complex shape of irregular parts, processing is difficult, so it is necessary to use advanced processing technology to ensure processing quality and efficiency. As an advanced machining equipment, CNC machine tool has the advantages of high precision, high efficiency and high automation, and is very suitable for machining irregular parts. However, due to the complex shape of irregular parts, the processing technology of CNC machine tools also needs to be adjusted and optimized accordingly.

 1. Machining difficulties of irregular parts

Complex process: due to the complex shape and irregular geometric structure of irregular parts, processing is difficult, so it is necessary to carry out detailed process planning and organization before processing, including process route design, tool selection, processing parameter setting, processing sequence arrangement, etc.

High accuracy requirements: The machining accuracy requirements of irregular parts are usually very high, even reaching 0.1mm or even micron level. In the process of processing, the control of processing parameters, the stability of processing equipment, the selection of processing tools and other aspects of the processing accuracy and stability put forward extremely high requirements. Once the processing accuracy and stability can not meet the requirements, it will lead to the quality of the parts is not up to standard, affecting the quality and performance of the entire product.

Low machining efficiency: Irregular parts have complex structures, and when machining these parts, CNC machines may require more complex programming and tool path planning to ensure that the desired shape is accurately machined. This can increase processing time and difficulty, resulting in relatively low efficiency.

2. Machining process design of CNC machine tool for irregular parts

2.1 Selection of machining tools

Because the tool is in the cutting state for a long time, its cutting performance and life are important indicators that must be considered when selecting the tool. Under normal circumstances, an equilateral diamond coated blade with a specific Angle (80° or 35°) can be selected to obtain a better cutting effect. Among them, the 80° equilateral diamond-coated blade is more suitable for processing harder materials or situations where larger cutting forces are required, because it provides greater tip strength and cutting force. The 35-degree blade is more suitable for processing softer materials or situations where finer cutting is required, as it can provide less cutting force and better surface quality.

We usually judge whether a machining tool should be replaced by three methods: (1) Observe the wear of the back tool face. When there are serious wear marks on the back tool surface, usually manifested as serious peeling of the coating, serious wear of the coating or significant changes in the color of the coating, we should replace the tool in time; (2) Observe the surface of the machined parts. Under the same cutting conditions, if the shape of the chip has changed greatly, for example, the cutting has changed from a long strip to a short broken or even a chip, or directly observe the color of the chip, if from silver to yellow or black, it indicates that the tool has been seriously worn; (3) Judge by the processed sound. If in the cutting process, the tool produces a sound that is significantly different from that of normal cutting, such as loud noise, harsh sound, significant change in timbre, etc., the tool should be replaced in time.

2.2 Selection of cutting parameters

The selection of cutting parameters should take into account the hardness and toughness of the processed material. For materials with higher hardness, the tool needs to withstand greater cutting forces, so the cutting amount needs to be appropriately increased to improve cutting efficiency and ensure the service life of the tool. For materials with high toughness, it is necessary to reduce the cutting amount to prevent excessive cutting force from causing workpiece deformation or tool damage.

The choice of cutting parameters also takes into account the material and type of the tool. Different materials and types of tools have different wear resistance and rigidity, so the selection of cutting parameters needs to be adjusted according to the characteristics of the tool. In general, carbide tools can withstand a larger cutting amount, and coated tools need to reduce the cutting amount to avoid the coating on the tool surface is peeled.

The type of tool will also affect the choice of cutting parameters, such as milling tools and turning tools in the cutting parameters will be different. In addition, processing requirements are also one of the important factors affecting the selection of cutting parameters.

2.3 Design of mechanical fixtures

For parts with complex shapes, the design of the fixture needs to be able to adequately fix the part to avoid displacement or deformation during processing. This requires the clamping force of the fixture to be large enough, and at the same time to avoid excessive stress on the parts, so as not to damage the parts. The fixture design also needs to take into account the size of the parts. The parts with irregular size may have some problems in fixture design, such as weak symmetry and difficult positioning.

When designing the fixture, it is necessary to consider how to ensure the accurate position of the parts in the fixture through the appropriate positioning method. The material and surface treatment of the fixture are also factors that cannot be ignored. The material of the fixture should have sufficient hardness and strength to ensure that the fixture is not deformed or damaged during long-term use. At the same time, the surface treatment of the fixture should also take into account the surface requirements of the parts to avoid damage or wear to the parts during the clamping process.

2.4 Determination of the benchmark

By carefully studying the drawings and technical requirements of the parts, the key parameters such as geometry, dimensional tolerance and surface roughness requirements of the parts are determined. These parameters will be the basis for determining the benchmark, and staff will need to operate in strict accordance with these requirements. In the actual processing process, the determination of the benchmark involves many aspects. The first is the positioning benchmark of the part, which refers to determining the specific position and direction of the part on the CNC machine tool. The second is the processing basis of the part, which refers to the relative position relationship between the machining of the part and the tool or workpiece table. By accurately determining the positioning datum and processing datum, it can be ensured that the parts will not be deviated during the processing process, so as to ensure the dimensional accuracy of the parts. The determination of the process datum includes the setting of machining parameters such as cutting speed, feed speed and cutting depth. The determination of these parameters directly affects the surface quality and machining efficiency of the parts.

2.5 Workpiece clamping problem

Different shapes and sizes of the workpiece need to use different clamping methods to ensure that the workpiece will not be displaced or deformed during the processing process, so as to ensure the processing accuracy and quality. When the staff is clamping the workpiece, it is necessary to do a good job of clamping the workpiece, that is, to ensure that the position and direction of the workpiece in the clamping fixture is correct to reduce the processing error. At the same time, the staff also need to consider the size and direction of the clamping force to avoid movement or deformation of the workpiece during processing. When clamping the workpiece, it is necessary to ensure that the contact surface between the workpiece and the fixture is fully in contact, and the clamping force of the fixture is evenly distributed. Poor contact surface and uneven clamping force will cause the workpiece to shift or deform during machining, affecting the machining accuracy. When the fixture is installed on the self-centering, it is necessary to ensure that the rotation axis of the control clamp and the spindle line of the lathe are controlled within 0.01mm.

2.6 Machining wheel frame problems

When selecting the machining wheel frame, it is necessary to consider the shape, size, weight and processing requirements of the parts. The design of the machining wheel frame should be stable and reliable to ensure that the parts will not be displaced or deformed during processing. When installing the machining wheel holder, it is necessary to ensure that it is fixed to the workbench of the CNC machine tool to avoid shaking or displacement during the machining process. At the same time, it is necessary to adjust the height, Angle and position of the machining wheel frame reasonably according to the shape and processing requirements of the parts to ensure that the parts can be correctly fixed and processed. The material and surface treatment of the processing wheel frame also need attention. The processing wheel frame should be made of high-strength and high-hardness materials to ensure that there will be no deformation or damage during processing. In addition, the surface of the machining wheel frame needs to be treated with finish to reduce the friction resistance when in contact with the part and improve the processing accuracy. In the process of processing, it is necessary to constantly check the fixing of the processing wheel frame to ensure its stability. If the processing wheel frame is found to be loose or deformed, it should be stopped immediately for maintenance to avoid affecting the processing of parts.

3 Conclusion

As an advanced processing equipment, with high precision, high efficiency, high automation and other advantages, CNC machine tools are highly suitable for machining irregular parts. However, the research on machining technology of NC machine tool for irregular parts is a relatively complicated subject. Through the reasonable selection of machining tools and cutting parameters, the scientific design of mechanical fixtures and the accurate determination of benchmarks, we pay attention to the problem of workpiece clamping and processing wheel frame, improve the processing efficiency and quality of irregular parts, reduce production costs, and enhance the competitiveness of enterprises.

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