Cutter for a lathe for metal. Types and sharpening of tools for a lathe for metal

Conditionally, any cutter for a lathe for metal is represented by two elements: the head and the holder.

The head is the performing part, consisting of a number of planes and cutting edges with a certain angle. Depending on the type of sharpening required, the cutter is given a certain angle.

The holder is responsible for fixing the tool in the lathe holder. It has a square or rectangular shape. There are a number of standard section sizes for each shape.

Types of construction

There are the following types of incisors for a lathe for metal:

• Straight lines. The holder and the head are located on one or parallel axes.
• Curved. The holder has a bent shape when viewed from the side.
• Rejected. The head is bent to the holder when viewed from above.
• Drawn. The width of the holder is greater than that of the head. The head is located on the same axis with the holder or is offset with respect to it.

If you rely on the well-known classification of devices in accordance with GOST, then they are divided into the following types:

• Having cutting edge on the basis of alloy steel. The tool is monolithic. It can be made of tool steel. Currently, its use is extremely rare.
• Stuffed with soldered hard alloys. The edge plate is soldered to the head. This is the most common species.
• Plates of hard alloys, fixed by means of a mechanical method. The cutting insert is fixed to the head with screws and clamps. Metal and cermets are used as a basis for replaceable incisors. This is the rarest species.

Classification in the direction of the forward movement

• The left model is fed to the left when taken in the left hand. The main working edge is located above the thumb.
• The right model, respectively, is fed to the right. The main working edge is under the thumb. In practice, it occurs more often.

Ways to set up adaptations

The tool for the lathe for metal can be distinguished by the installation method with respect to the surface for processing:

• Radial view. When machining, the cutter takes a right angle to the workpiece axis for machining. This method is widely applicable in industrial enterprises. The cutter has a unified design of fastening on machine tools. It also has a more convenient choice of the geometrical positions of the cutting part.
• Tangential. When machining, the cutter is positioned to the axis of the workpiece at an angle different from the straight. It has a more complicated method of fastening and is used on turning devices that allow to produce high purity treatment.

Processing difference

Cutters can be divided and by the way of processing:

• Finishing;
• Roughing;
• Semi-precious;
• For works made with special fineness.

The roughness of the workpiece is affected by the radius of curvature of the top of the device. A smooth surface is achieved by using a tool sharpened under a large radius.

Types of turning tools

A tool for turning a metal lathe has many types. The most common are:

• Walk-through. It creates the contours of the part during rotation, and also provides turning, trimming when feeding in the transverse and longitudinal directions.
• Boring view creates a variety of grooves, grooves and holes. Can make through holes.
• The scoring model is applied only for the transverse direction of feed for turning parts having a stepped shape and end.
• Cutting. Its feed is carried out in the transverse direction with respect to the axis of rotation. It produces grooves and grooves around the part, it is used for separating the finished product.
• Threaded. Threads of any kind on parts with any shape of section. This species can be curved, straight or round.
• Shaped. It produces turning parts of complex construction, can take out various chamfers from inside and outside.

A set of tools for a lathe for metal can be purchased at specialized stores or ordered via the Internet.

The base of the incisors

The materials from which the devices are made are divided into three categories:

• The first is designed for cutting devices used at low speed. These are instrumental or carbonaceous metals with a hardness hardening index of 60-64. When the temperature of the tool for the turning tool is raised above 200-240 degrees, the quality of its cutting is markedly reduced, so in practice they are used infrequently. This group includes devices based on chromotungsten, chromium-silicon and alloy steel with a level of resistance to temperatures up to 300 degrees.
• The second category of incisors is applied at a high level of rotation of the lathe head. The basis of such devices is steel with a high category of cutting P12 P9 or P9K5F2. After quenching, the material hardens to 62-65 and retains all its properties at a temperature of 650 degrees. Not to be rubbed for a long time.
• The third category consists of tools based on cermets. These are carbide-tipped devices that function at high machine speed and withstand a heating temperature of up to 1000 degrees. Cast iron and some parts from non-ferrous alloys are sharpened by devices based on tungsticcobalt (VK6 for finishing and semi-finished execution, VK8 for primary processing). The steel is grinded with a hard alloy titanium-volatile cobalt T15K6. In this case, pure processing is carried out.

Accessories for desktop lathes

The incisors for the desktop lathe for metal have a small section of 8 x 8 and 10 x 10 mm. They are used for processing small parts.

Incisors in the form of replaceable plates

The cutter for the metal lathe of category Т5 К10 is used for primary and intermittent turning. On the basis of cubic boron nitride, replaceable plates are made for the processing of metals characterized by a special hardness, including cast iron. Non-ferrous metals are grinded by polycrystalline diamond.

Plates can be replaceable. They are inserted into the holder. Some models contain chipbreakers, excellent crushing chips with low feed and surface sharpening. Such plates are used for high-precision cutting of stainless steel and other types of steel.

Sharpening the incisors

Any types of incisors, in addition to interchangeable plates, are subject to sharpening from time to time. Sharpening the incisors for a lathe for metal ensures that the required angles and shapes are achieved. In industrial conditions it is carried out on specialized units.

This process at home can be done through chemical reagents and grinding wheels. Manual grinding is inferior in quality to the industrial one. The main thing here is the correct selection of the grinding wheel.

To sharpen the incisors of hard alloys, a circle of green carborundum is taken. Turning tools made of carbonaceous materials are sharpened with circles of corundum.

Sharpening is recommended to be performed by means of cooling (uniform supply of cold water to the place of contact of the circle with the cutter being processed). You can perform a dry grinding, but after that the part should not be lowered into cold water, as it can crack.

The standard scheme of the grinding process

First of all, the main back edge is subject to treatment, then the rear auxiliary one and only then the front part. At the very end of the process, the top of the tool (radius of curvature) is machined. The sharpened cutter should be constantly moved on the surface of the grinding wheel and slightly pressed against the mold.

An obligatory component of the process is the debugging of the cutter, or rather the cutting edges (areas near the edge, the width of which reaches 4 mm).

Devices made from hard alloys are sharpened by means of copper donkeys, which are lubricated with a special composition in the form of a paste or a mixture of kerosene and boron carbide.

The other types of cutting tools are sharpened with a small donkey with a low kind of abrasiveness, moistened with engine oil or kerosene.

Making homemade cutters

You can also make self-made cutters for a lathe for metal. As a basis for such devices, unnecessary broken drills are taken.

Centering on the basis of drills does not break. In particular, they are suitable for turning machines of the old modification. They are subject to multiple repetition. Their service life is 30 years.

Homemade cutters for a mini lathe for metal are made from the segment of the Geller saw. It is cut with a cutting disc.

How to make the right choice of tool?

When choosing a cutter, it is necessary to take into account a number of recommendations.

Determine with what kind of metal you have to work, what kind of processing operations you plan and how much the load will be tested by the cutter.

Decide what is most important - the accuracy of compliance with the geometry of the product or the level of processing its surface. Depending on this, the cutter is selected in accordance with the classification characteristics and geometrical proportions.

Indicate for yourself how important it is to comply with the wear resistance of the device and how long it should remain unchanged.