CNC Machining Cutting Tools

Basic classification of cutting tools

According to the end geometry:

Flat bottom end mill

Flat bottom R angle end mill

Ball end mill

Indexable inlaid end mill

Other classification methods:

Tools can be divided into five categories according to the form of the workpiece surface:

■ Processing various external surface tools, including turning tools, planers, milling cutters, external surface broaches and files, etc.;

■ Hole processing tools, including drills, reaming drills, boring cutters, reamers and inner surface broaches, etc.;

■ Thread processing tools, including taps, dies, automatic opening and closing thread cutting heads, thread turning tools and thread milling cutters, etc.;

■ Gear processing tools, including hobs, gear shaping cutters, gear shaving cutters, bevel gear processing tools, etc.;

■ Cutting tools, including toothed circular saw blades, band saws, bow saws, cutting turning tools, saw blade milling cutters, etc.

In addition, there are combined tools.

According to the cutting motion mode and the corresponding blade shape, cutting tools can be divided into three categories:

■ General tools, such as turning tools, planers, milling cutters (not including shaped turning tools, shaped planers and shaped milling cutters), boring tools, drills, reamers, reamers and saws, etc.;

■ Forming tools. The cutting edge of this type of tool has the same or nearly the same shape as the section of the workpiece to be processed, such as forming turning tools, forming planers, forming milling cutters, broaches, conical reamers and various thread processing tools, etc.;

■ Generating tools are used to process gear tooth surfaces or similar workpieces, such as hobs, gear shapers, gear shaving cutters, bevel gear planers, and bevel gear milling cutters.

structure

The structure of various tools is composed of a clamping part and a working part. The clamping part and the working part of the cutter with integral structure are made on the cutter body; the working part (tooth or blade) of the cutter with insert structure is mounted on the cutter body.

The clamping part of the tool has two types: with hole and with shank. Hole cutters rely on the inner hole to be sleeved on the main shaft or mandrel of the machine tool, and transmit the torsion moment with the aid of axial keys or face keys, such as cylindrical milling cutters, sleeve face milling cutters, etc.

Shank tools usually have rectangular shank, cylindrical shank and tapered shank. Turning tools, planers, etc. are generally rectangular shanks; tapered shanks rely on taper to bear axial thrust and transmit torque by friction; cylindrical shanks are generally suitable for smaller twist drills, end mills and other tools. The friction force generated transmits the torsional moment. The shank of many shank tools is made of low-alloy steel, while the working part is made of high-speed steel butt-welded two parts.

The working part of the tool is the part that generates and processes the chips, including the cutting edge, the structure to break or roll up the chips, the space for chip removal or storage, and the passage of cutting fluid. The working part of some tools is the cutting part, such as turning tools, planers, boring cutters and milling cutters, etc.; the working part of some tools includes cutting parts and calibration parts, such as drills, reamers, reamers, and inner surface drawing. Knife and tap etc. The function of the cutting part is to remove chips with the cutting edge, and the function of the calibration part is to polish the cut surface and guide the tool.

The structure of the working part of the tool has three types: integral type, welding type and mechanical clamping type:

■ The overall structure is to make a cutting edge on the cutter body;

■ The welding structure is to braze the blade to the steel body;

■ There are two kinds of mechanical clamping structures, one is to clamp the blade on the cutter body, and the other is to clamp the brazed cutter head on the cutter body.

Cemented carbide cutting tools are generally made of welded structure or mechanical clamping structure; porcelain cutting tools adopt mechanical clamping structure.

The geometric parameters of the cutting part of the tool have a great influence on the cutting efficiency and the processing quality. Increasing the rake angle can reduce the plastic deformation when the rake face squeezes the cutting layer, reduce the friction resistance of the chip flowing through the front, thereby reducing the cutting force and cutting heat. However, increasing the rake angle will reduce the strength of the cutting edge and reduce the heat dissipation volume of the cutter head.

When choosing the angle of the tool, it is necessary to consider the influence of many factors, such as workpiece material, tool material, machining properties (rough and fine machining), etc., which must be selected reasonably according to the specific situation. Generally speaking, the tool angle refers to the marking angle used for manufacturing and measurement. In actual work, due to the different installation positions of the tool and the change of the cutting motion direction, the actual working angle and the marked angle are different, but the difference is usually very small. .