How to correctly select cutting tools and program

2022-07-30
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How to correctly select tools and program for NC machine tools (I)

the selection of NC tools and the determination of cutting parameters are important contents in NC machining process. It not only affects the machining efficiency of NC machine tools, but also directly affects the machining quality. The development of cad/cam technology makes it possible to directly use CAD design data in NC machining, especially the connection between DNC system microcomputer and NC machine tool, so that the whole process of design, process planning, clothing tensile testing machine and programming can be completed on the computer, and it is generally not necessary to output special process documents

at present, many cad/cam software packages provide automatic programming function. These software usually prompt relevant problems of process planning in the programming interface, such as tool selection, machining path planning, cutting parameter setting, etc. as long as the programmers set relevant parameters, they can automatically generate NC programs and transmit them to the NC machine tool for processing

therefore, the tool selection and cutting amount determination in NC machining are completed in the human-computer interaction state, which is in sharp contrast to ordinary machine tool machining. At the same time, it also requires programmers to master the basic principles of tool selection and cutting amount determination, fully consider the characteristics of NC machining during programming, and be able to correctly select tools and cutting amounts

types and characteristics of commonly used NC machining tools

NC machining tools must adapt to the characteristics of high speed, high efficiency and high automation of NC machine tools, generally including general-purpose tools, general-purpose connecting tool handles and a small number of special tool handles. The tool handle should be connected with the tool and installed on the power head of the machine tool, so it has been gradually standardized and serialized. There are many ways to classify NC tools. According to the tool structure, it can be divided into: ① integral type; ② Inlay type adopts welding or machine clamp type connection, and machine clamp type can be divided into two types: non transposable and transposable; ③ Special types, such as compound cutting tools, shock absorbing cutting tools, etc. According to the materials used to manufacture cutting tools, they can be divided into: ① high speed steel cutting tools; ② Cemented carbide cutting tools; ③ Diamond cutting tools; ④ Other material cutting tools, such as square boron nitride cutting tools and ceramic cutting tools, can be divided into metal material testing machine, non-metal material testing machine, dynamic balance testing machine, vibration table and nondestructive testing machine according to the classification method. In terms of cutting technology, it can be divided into: ① turning tools, including excircle, inner hole, thread, cutting tools, etc; ② Drilling tools, including drill bits, reamers, taps, etc; ③ Boring tools; ④ Milling tools, etc. In order to meet the requirements of CNC machine tools for tool durability, stability, easy adjustment, replaceability, etc., machine clamp indexable tools have been widely used in recent years. In terms of quantity, they account for 30% ~ 40% of the whole CNC tools, and the metal removal amount accounts for 80% ~ 90% of the total

compared with the tools used in ordinary machine tools, CNC tools have many different requirements, mainly with the following characteristics: ① good rigidity (especially rough machining tools), high precision, low vibration resistance and thermal deformation; ② Good interchangeability, convenient for quick tool change; ③ High service life, stable and reliable cutting performance; ④ The size of the tool is easy to adjust to reduce the adjustment time of tool change; ⑤ The cutter shall be able to reliably break or curl chips to facilitate the removal of chips; ⑥ Serialization and standardization to facilitate programming and tool management

selection of NC machining tools high and low temperature electronic universal testing machine In the high temperature experiment, the selection of

tools is carried out in the human-computer interaction state of NC programming. The cutting tool and tool holder shall be correctly selected according to the processing capacity of the machine tool, the performance of workpiece materials, processing procedures, cutting parameters and other relevant factors. The general principle of tool selection is: convenient installation and adjustment, good rigidity, high durability and precision. On the premise of meeting the processing requirements, try to select a shorter tool handle to improve the rigidity of tool processing

when selecting a tool, the size of the tool should match the surface size of the workpiece to be machined. In production, end mills are often used to process the peripheral contour of plane parts; When milling the plane, the carbide blade milling cutter should be selected; Select high-speed steel end milling cutter when machining boss and groove; When processing the rough surface or rough hole, the corn milling cutter with cemented carbide blade can be selected; Ball end milling cutter, ring milling cutter, conical milling cutter and disk milling cutter are often used for machining some solid surfaces and variable angle profiles

when machining free-form surfaces (molds), because the cutting speed at the end of the ball head tool is zero, in order to ensure the machining accuracy, the cutting line spacing generally adopts the top dense distance, so the ball head is often used for surface finishing. The flat end cutter is superior to the ball end cutter in terms of surface machining quality and cutting efficiency. Therefore, as long as no cutting is ensured, the flat end cutter should be preferred for both rough machining and finish machining of curved surfaces. In addition, the durability and accuracy of the tool have a great relationship with the tool price. It must be noted that in most cases, the selection of a good tool increases the tool cost, but the resulting improvement in processing quality and efficiency can greatly reduce the overall processing cost

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