The most common operation in the production of various parts is, perhaps, turning. The tool industry produces a large number of varieties and types of cutters for processing bodies of revolution on lathes, as well as for boring holes on jig boring units and machining centers. Turning allows you to remove the allowance and obtain products with a cylindrical and shaped surface (including threaded). You can also cut the bar into blanks of the desired length.
Design of cutting tools for turning
Despite the large number of types of cutters, they all have the same structural elements. Both a conventional turning tool with a brazed insert made of tool steel and a tool with an interchangeable cutting insert made of modern powder materials are similar in design. Each cutter has a holder. She isattaches to a CNC lathe turret or a four-position universal machine tool holder.
For any type of cutter, a mandatory element is also the head, on which a plate of tool steel (type TK15) is soldered. Brazed insert tools are rarely used today. Enterprises buy mainly cutter holders with quick-release inserts. For the manufacture of such plates, the most modern materials obtained by means and methods of powder metallurgy are used.
General classification of turning tools
Depending on the shape of the tool holder, the cross section is divided into rectangular and round cutters. Rectangular in cross-section, the holder has cutters for processing external surfaces (thread, grooves, cylinder, and so on). A rounded holder is typical for cutters that machine internal surfaces (internal threads, internal grooves for bearing circlips, holes, and so on). These types of cutters (with a round holder) are installed in the turret through a special adapter that allows you to adjust the angle of rotation of the cutter around the axis in order to align the cutter tip with the axis of rotation of the workpiece. If the tip of the cutter does not coincide with the axis of rotation of the workpiece, then the tool will be subject to increased wear due to improper chip flow and increased load.
Another sign by which turning tools are classified is the direction of the cutting feed. On this basis, the incisors are divided into right and left.
Depending on the type of working part of the tool, the cutters are straight and bent.
In addition, there are cutters of solid and composite types. Composite-type turning tools are collapsible. The cost of such cutters is an order of magnitude higher than a conventional tool. Composite heads are complex and made from very expensive materials.
Classification of turning tool depending on orientation relative to the workpiece
On this basis, the entire turning tool can be divided into the following types: tangential, parallel, radial.
The tangential tool is set to the axis of rotation of the workpiece at an acute angle. In this way, chamfers and other shaped surfaces are obtained. Theoretically, chamfers can be turned by combining the longitudinal and transverse feeds. However, this method requires a highly skilled turner and is not always feasible.
Parallel setting is used for drilling and boring holes along the axis of rotation of the workpiece from the end side.
Radial setting is used for turning outside surfaces.
Main types of turning tools for metal
Not only metals and steels are subjected to turning, but also other materials: wood, plastic and even glass. And, of course, there are no such cutters that would be suitable for processing all these materials. And if earlier high-speed steel TK15 (and its analogues) was used almost everywhere, today thisthe material cannot meet the growing demand for quality and durable tools. Such incisors become dull very quickly, and they need to be re-sharpened. And this is time and money for the salary of a highly qualified specialist.
It is much more profitable and convenient to use cutters with interchangeable inserts. The durability of such inserts made of powder composite materials is an order of magnitude higher than traditional tool steel. In addition, one such plate can have up to six working faces. The insert allows machining at very high cutting speeds. When the working face becomes unusable, it is enough just to turn it on the other side. The positioning accuracy of such an insert is very high, which means that there is no need to stop the equipment for readjustment.
The tool industry has mastered the production of cutting inserts for a wide range of materials: steel, copper, aluminum, plastic and so on. The use of inserts for their intended purpose guarantees the durability, roughness and cleanliness of the machined surface declared by the tool manufacturer.
Classification of cutters by type of processing
In accordance with the established and valid GOST, the types of cutters by type of processing are as follows: for black turning, for finishing (semi-finishing) processing.
The cutting insert for rough peeling of forgings and rolled products has a large radius at the top, which allows you to remove a significant allowance in one pass (up to 4 millimeters or more on a machine withCNC).
Finishing inserts, as well as inserts for processing non-ferrous metals (aluminum and copper) have a small radius at the top of the cutter. Processing with such inserts is carried out at very high speeds (from a thousand or more units per minute), which allows you to get a very high-quality and clean surface.
On this basis, it is possible to classify both passing turning tools and various types of boring tools.
Description of threaded tools for external threads
As the name implies, this cutter is used to process threaded surfaces.
The thread can be cut both from the outside and from the inside. A threaded cutter for external threads looks like a straight through type cutter. The only difference is the sharpening angle - it is 60 degrees (if you need to cut a metric thread) or 55 degrees (to get an inch thread).
Description of tapping tools for cutting internal threads
Cutter for cutting internal threads looks very much like a tool for boring the inner diameter of holes. The differences are the same: shaped sharpening at a certain angle.
Sharpening, as well as installing the tool on the machine and setting it up, is a very complicated matter. Only a specialist with extensive experience in such work can cope with this task. The use of thread cutters with indexable inserts solves this problem and greatly simplifies the process of setting up the machine.
Characteristicthrough cutters
The through cutter is most commonly used in turning. Without it, it is simply impossible to give a forging or a billet from a bar the shape and dimensions necessary for subsequent technological operations. Therefore, the through passage refers to the main type of incisors.
This type is used to remove the allowance on the outer surface of the rotation body, as well as to trim the end surfaces. The angle at the top can be different: 45, 60, 75 and even 90 degrees. The value of the angle is dictated by the purpose of the cutter. Purpose and types of through cutters: peeling, trimming, finishing.
Features of turning tools for wood
All turning cutting tools have one purpose - the processing of workpieces (bodies of rotation) on machine tools and giving them a given shape. But despite this, the very principle of the tool on wood and the very physics of the cutting process are strikingly different from the processes occurring in the process of cutting metal.
The main difference is the low cutting force. Most woodworkers prefer to use hand tools in their work. This is how exclusive products are created. But for turning wood in conditions of serial and mass production, so-called copiers are used. The essence of this technology is as follows: the probe moves along the template and transmits the movement to the working body of the machine, as a result of which the contour of the part is formed.
It should be noted that a quality product can only be obtained with manualprocessing. Workpieces obtained using automatic and semi-automatic methods require subsequent finishing and grinding with polishing.
