Determination of tool selection and cutting amount in CNC machining

Abstract: The remarkable feature of modern knives is the rapid development of structural innovation. With the continuous expansion of the field of computer applications, mechanical processing has also begun to use the digital pull technology, when the tool selection and cutting amount put forward higher requirements. In this paper, we will discuss the determination of tool selection and cutting in CNC machining.

First, scientific selection of CNC tools

1. The principle of selecting CNC tools The tool life is closely related to the cutting amount. When setting the amount of cutting, you should first choose a reasonable tool life, and a reasonable tool life should be based on the optimization goal. Generally, the highest productivity tool life and the lowest cost tool life are classified. The former is determined according to the minimum single working time target, and the latter is determined according to the lowest operating cost target.

The following points can be considered when selecting the tool life based on tool complexity, manufacturing and sharpening costs. Complex and high precision tool life should be chosen to be higher than single-edged tools. For the machine clamp indexable tool, due to the short tool change time, in order to give full play to its cutting performance and improve production efficiency, the tool life can be selected to be lower, generally taking 15-30min. For multi-tool machines, combination machine tools and automatic machining tools with complicated tools, tool changes and tool adjustments, the tool life should be selected higher, especially for tool reliability. When the productivity of a certain process in the workshop limits the productivity of the entire workshop, the tool life of the process should be selected to be lower. When the total plant expenditure M is greater than the unit time of a certain process, the tool life should also be selected. Got lower. In the case of large-scale finishing, in order to ensure that at least one pass is completed and the tool is changed midway during cutting, the tool life should be determined according to the accuracy of the part and the surface roughness. Compared with the ordinary machine tool processing method, CNC machining puts higher requirements on the tool, which not only needs good quality, high precision, but also requires dimensional stability and high durability. The performance of the break and row performance performance is also convenient to install and adjust. Meet the high efficiency requirements of CNC machine tools. The tools selected for CNC machine tools often use tool materials that are suitable for high-speed cutting (such as high-speed steel, ultra-fine-grained carbide) and use indexable inserts.

2. Select the general-purpose turning tool, the sharp-shaped turning tool, the circular-shaped turning tool and the three types commonly used in CNC turning tools. The forming turning tool is also called the model turning tool, and the contour shape of the machined part is completely determined by the shape and size of the turning edge of the turning tool. In CNC turning, common forming turning tools include small radius arc turning tools, non-rectangular grooving knives and thread knives. In CNC machining, the turning tool should be used with little or no use. The pointed tool is a turning tool characterized by a linear cutting edge. The cutting edge of this type of turning tool consists of straight main and auxiliary cutting edges, such as 900 inner and outer turning tools, left and right end turning tools, grooving (cutting) turning tools and various outer and inner edges with small chamfering edges. Hole turning tool. The selection method of geometrical parameters of the pointed tool (mainly geometric angle) is basically the same as that of ordinary turning, but should be comprehensively considered in combination with the characteristics of CNC machining (such as machining route, machining interference, etc.), and should take into account the tip of the tool itself. strength.

The second is a circular arc turning tool. The circular turning tool is a turning tool characterized by a circular arc-shaped cutting edge with a small degree of roundness or line contour error. Each point of the turning edge of the turning tool is the cutting edge of the circular arc turning tool. Therefore, the cutting point is not on the arc but on the center of the arc. The circular turning tool can be used for turning the inner and outer surfaces, and is particularly suitable for turning various smooth joints (concave) forming surfaces. When selecting the radius of the turning edge of the turning tool, the radius of the arc of the cutting edge of the two-point cutting tool should be less than or equal to the minimum radius of curvature on the concave contour of the part, so as to avoid the occurrence of shallow dryness. The radius should not be too small, otherwise it is not only difficult to manufacture. The tool cutter may be damaged due to the weakness of the tool tip or the poor heat dissipation of the tool body.

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