Types and selection of commonly used tools in CNC machining centers - News - Global IC Trade Starts Here Free Join

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1. The types and characteristics of commonly used tools for processing

CNC machining tools must adapt to the high speed, high efficiency and high degree of automation of CNC machine tools. Generally, they should include general-purpose tools, universal connecting shanks and a small number of special shanks. The shank is to be connected to the tool and mounted on the power head of the machine, so it has been standardized and serialized.

1.1 There are many ways to classify CNC tools.
a. According to the tool structure, it can be divided into 1) integral type;
2) Inlaid type, using welding or machine clamp type connection, the machine clamp type can be divided into two types: non-indexing and indexable;
3) Special types, such as composite tools, shock-absorbing tools, etc.

b. According to the materials used to manufacture the tool, it can be divided into:
1) high speed steel cutter;
2) Carbide tools;
3) diamond cutters;
4) Other material tools, such as cubic boron nitride tools, ceramic tools, etc.

c. From the cutting process can be divided into:
1) Turning tools, such as outer circle, inner hole, thread, cutting tool, 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 durable, stable, easy to adjust, changeable, etc., in recent years, machine-clampable indexable tools have been widely used, reaching 30%-40% of the total CNC tools in quantity, metal removal The amount accounts for 80% to 90% of the total.

1.2 Compared with the tools used on ordinary machine tools, there are many different requirements for CNC tools. The main features are as follows:

1) Good rigidity (especially rough machining tools), high precision, anti-vibration and small thermal deformation; good interchangeability, easy to change the knife quickly;
2) High life, stable and reliable cutting performance;
3) The size of the tool is easy to adjust to reduce the tool change time;
4) The tool should be able to reliably break the chip or the chip to facilitate the removal of the chip;
5) Serialization standardization for programming and tool management.

The selection of the tool is carried out in the human-computer interaction state of the NC programming. The tool and the tool holder should be selected correctly according to the machining capacity of the machine tool, the performance of the workpiece material, the cutting amount of the machining process, and other relevant factors. The general principle of tool selection is: easy installation and adjustment, good rigidity, durability and high precision. Under the premise of meeting the processing requirements, try to choose a shorter tool holder to improve the rigidity of the tool processing.
1) When selecting a tool, make the size of the tool match the surface size of the workpiece to be machined. In the production, the peripheral contour of the plane parts is often processed by the end mill; when milling the plane, the cemented carbide insert milling cutter should be selected, and when the boss and the groove are machined, the high-speed steel end mill is selected; the surface of the blank is processed or roughed. For the hole, the corn milling cutter with the carbide insert can be selected; for the machining of some three-dimensional and variable bevel contours, ball-end milling cutters, ring milling cutters, conical milling cutters and disc milling cutters are often used.

2) When the free-form surface (mold) is processed, since the cutting speed of the end of the ball-end tool is zero, in order to ensure the machining accuracy, the cutting distance is generally the tip-tight distance, so the ball head is often used for the finishing of the curved surface. The flat-blade tool is superior to the ball-end knives in terms of surface quality and cutting efficiency. Therefore, the flat-blade knives should be preferred if the surface is roughed or finished under the premise of ensuring no cutting. In addition, the durability and accuracy of the tool are highly dependent on the tool price. It must be noted that in most cases, the choice of a good tool increases the tool cost, but the resulting processing quality and processing efficiency increase. , can make the entire processing cost greatly reduced.

3) In the machining center, various tools are installed on the tool magazine, and the tool selection and tool pressing actions are performed at any time according to the program. Therefore, a standard tool holder must be used in order to quickly and accurately load the standard tool for drilling, boring, expanding, milling, etc. onto the machine tool spindle or tool magazine. The programmer should be aware of the structural dimensions, adjustment methods, and adjustment range of the tool holder used on the machine to determine the radial and axial dimensions of the tool during programming. At present, China's machining center adopts TSG tool system. Its tool holder has two types: straight handle (3 specifications) and taper shank (4 specifications), including 16 different handles.

4) In the processing process of economical CNC machine tools, since the sharpening, measurement and replacement of the tools are mostly manual and manual, the occupation time is long. Therefore, the arrangement order of the tools must be arranged reasonably. Generally, the following principles should be followed: 1 Minimize the number of tools; 2 After a tool is clamped, all the machining steps that can be performed should be completed; the rough-finished tools should be used separately, even for tools of the same size; Milling and drilling; 5 first surface finishing, then 2D contour finishing; 6 When possible, the automatic tool change function of CNC machine tools should be used as much as possible to improve production efficiency.