What do you know about the types and uses of turning tools? Today, the editor has found useful content for you, which is worth learning over and over again.
1. Types and uses of turning tools
Turning tools are the most widely used single-edged tools. It is also the basis for learning and analyzing various types of cutting tools. Turning tools are used on various lathes to process outer circles, inner holes, end faces, threads, grooves, etc. According to the structure, turning tools can be divided into solid turning tools, welding turning tools, machine clamp turning tools, indexable turning tools and forming turning tools. Among them, indexable turning tools are increasingly widely used, and their proportion in turning tools is gradually increasing.
1. Carbide welding turning tool
The so-called welded turning tool is a turning tool that is used after cutting a slot on the carbon steel tool holder according to the geometric angle requirements of the tool, using solder to weld the carbide blade into the slot, and sharpening it according to the selected geometric parameters. knife.
2. Machine clamp turning tool
Machine-clamped turning tools are turning tools that use ordinary blades and use mechanical clamping to clamp the blades on the tool holder. This type of knife has the following characteristics:
(1) The blade does not undergo high-temperature welding, which avoids defects such as the decrease in blade hardness and cracks caused by welding, and improves the durability of the tool;
(2) Due to the improved durability of the tool, the use time is longer, the tool changing time is shortened, and the production efficiency is improved;
(3) The tool holder can be reused, which not only saves steel but also improves the utilization rate of the blade. The blade is recycled and remanufactured by the manufacturer, which improves economic benefits and reduces tool costs;
(4) After the blade is reground, the size will gradually become smaller. In order to restore the working position of the blade, a blade adjustment mechanism is often provided on the turning tool structure to increase the number of regrindings of the blade;
(5) The end of the pressure plate used to compress the blade can function as a chip breaker.
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3. Indexable turning tool
Indexable turning tools are machine tool turning tools that use indexable inserts. After a cutting edge is blunted, it can be quickly replaced by a new adjacent cutting edge, and the work can continue. The blade is not scrapped until all the cutting edges on the blade have been blunted. After replacing the new blade, the turning tool can continue to work. Compared with welding turning tools, indexable tools have the following advantages:
(1) High tool life. Since the blade avoids defects caused by high temperatures of welding and sharpening, the tool geometric parameters are completely guaranteed by the blade and tool holder grooves, and the cutting performance is stable, thus increasing the tool life;
(2) High production efficiency. Since machine tool operators no longer need to sharpen tools, auxiliary time such as downtime for tool changes can be greatly reduced;
(3) It is conducive to the promotion of new technologies and new processes. Indexable knives are conducive to promoting the use of new tool materials such as coatings and ceramics;
(4) Helps reduce tool costs. Due to the long service life of the tool holder, the consumption and inventory of the tool holder are greatly reduced, the management of the tool is simplified, and the cost of the tool is reduced;
Clamping characteristics and requirements for indexable turning tool inserts:
(1) High positioning accuracy. After the blade is indexed or replaced with a new blade, the change in the tool tip position should be within the allowable range of the workpiece accuracy;
(2) The blade is clamped reliably. It should be ensured that the contact surfaces of the blade, tool pad and tool holder are in close contact and can withstand impact and vibration, but the clamping force should not be too large and the stress distribution should be uniform to avoid crushing the blade;
(3) Chip removal is smooth. It is best to have no obstacles in front of the blade to ensure smooth chip discharge and easy observation;
(4) Easy to use. It is convenient and quick to change the blade and replace it with a new one, and the structure of small-sized tools should be compact. When meeting the above requirements, the structure should be as simple as possible and easy to manufacture and use.
4. Forming turning tool
The forming turning tool is a special tool for processing the forming surface of the rotary body. Its blade shape is designed according to the profile of the workpiece. It can be used on various lathes to process the forming surfaces of the internal and external rotary bodies. When processing parts with a forming turning tool, the surface of the part can be formed at one time. It is easy to operate and has high productivity. After processing, it can reach the tolerance level IT8~IT10, the roughness is 10~5μm, and it can ensure high interchangeability. However, the manufacturing of forming turning tools is complicated and costly, and the working length of the cutting edge is wide, so it is easy to cause vibration. Forming turning tools are mainly used to process large batches of medium and small-sized parts with formed surfaces.
In order to make good cuts on a lathe, it is very important to prepare and use the tool correctly. Different situations require different shapes of turning tools, and cutting different materials requires the cutting edge to have different angles. There is also a certain relative relationship between the position and speed of the turning tool and the workpiece. The turning tool itself should also have sufficient hardness, strength, wear resistance, and heat resistance. Therefore, when selecting turning tool materials, tool angle, etc. are all important considerations.
2. Classification and application of turning tool materials
The improvement and development of tool materials is one of the important topics in the current development of metal processing, because good tool materials can not only complete cutting work effectively and quickly, but also maintain tool life. Commonly used turning tool materials include the following:
1. High carbon steel
High carbon steel turning tools are a type of carbon steel with a carbon content of 0.8% to 1.5%. They are used after quenching and hardening. Due to the friction during cutting, they are easily tempered and softened, and are replaced by other tools such as high-speed steel. Generally only suitable for cutting soft metal materials, commonly used ones include SK1, SK2, SK7, etc.
2.High speed steel
High-speed steel is a steel-based alloy commonly known as white turning tool. It is made of carbon steel with a carbon content of 0.7%~0.85% by adding alloying elements such as W, Cr, V and Co. For example, 18-4-4 high-speed steel contains 18% tungsten, 4% chromium and 4% vanadium. The friction heat generated during cutting of high-speed steel turning tools can be as high as 6000°C. It is suitable for thread turning speeds below 1000rpm. Generally, high-speed steel turning tools such as SKH2, SKH4A, SKH5, SKH6, SKH9, etc. are commonly used.
3. Non-cast iron alloy cutting tools
This is an alloy of cobalt, chromium and tungsten. Because it is difficult to cut and process, it is made by casting, so it is also called superhard cast alloy. The most representative one is stellite. Its tool toughness and wear resistance are excellent. At 8200℃ Its hardness remains unaffected, its heat resistance is much higher than that of high-speed steel, and it is suitable for high-speed and deeper cutting work.
4. Sintered carbonized cutting tools
Carbide tools are products of powder metallurgy. The main component of tungsten carbide tools is 50% to 90% tungsten, with titanium, molybdenum, tantalum, etc. added as a binder and cobalt powder as a binder, and then heated and sintered. The hardness of carbonized tools is higher than other materials and is suitable for cutting harder metals or stones. Because the material is brittle and hard, it can only be made into sheets and then welded to a tough handle. When the blade becomes dull or cracked, You can replace another cutting edge or a new blade. This type of turning tool is called a disposable turning tool.
According to the different cutting properties of the international standard (ISO), carbonized tools are divided into three categories: P, M, and K, and are marked with three colors: blue, yellow, and red:
Category P is suitable for cutting steel. There are six categories: P01, P10, P20, P30, P40, and P50. P01 is a high-speed fine turning tool with a small number and high wear resistance. P50 is a low-speed rough turning tool with a large number and high toughness. , the handle is painted blue for identification;
Type K is suitable for cutting brittle and hard materials such as stone and cast iron. There are five types: K01, K10, K20, K30, and K40. K01 is a high-speed fine turning tool, and K40 is a low-speed rough turning tool. These tool handles are painted red to identify them;
Type M is between Type P and Type M and is suitable for cutting materials with greater toughness. This type of tool holder is painted yellow to identify it.
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5. Ceramic turning tool
Ceramic turning tools are made from aluminum oxide powder, adding a small amount of elements, and then sintered at high temperature. Its hardness, heat resistance, and cutting speed are higher than those of tungsten carbide. However, because they are brittle, they are not suitable for discontinuous or heavy turning. They are only suitable for discontinuous or heavy turning. Suitable for high-speed finishing.
6.Diamond cutter
For advanced surface processing, round or industrial diamonds with edges on the surface can be used for light processing. It can obtain a smoother surface and is mainly used for precision turning of copper alloys or light alloys. High speed must be used during turning, with a minimum speed of 60~100m/min, usually 200~300m/min.
7. Boron oxide
Cubic boron oxide (CBN) is a material that has been promoted in recent years. Its hardness and wear resistance are second only to diamond. This tool is suitable for processing hard and wear-resistant iron family alloys, nickel-based alloys and cobalt-based alloys.
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3. Shape and usage of turning tools
1. Generally, the following types of turning tool tips are used:
(1) Rough turning tool: It is mainly used to cut large and redundant parts to make the diameter of the workpiece close to the required size. Surface finish is not important in rough turning, so the tool tip can be ground to a sharp peak, but the tip usually needs a slight roundness to avoid breakage.
(2) Fine turning tool: This blade can be sharpened with a whetstone to produce a very smooth surface. Generally speaking, the round nose of fine turning tools is larger than that of rough turning tools.
(3) Round nose turning tool: It is a commonly used turning tool that can be used for many different types of work. It can be used for turning left and right when grinding the top surface, and can also be used for turning brass. This turning tool can also form an arc surface on the shoulder angle and can also be used as a precision turning tool.
(4) Cutting turning tool: Only the end is used to cut the workpiece. This turning tool can be used to cut materials and turn grooves.
(5) Screw turning tool (dental tool): used for turning screws or nuts. According to the form of the thread, it is divided into 60-degree or 55-degree V-shaped tooth tool, 29-degree trapezoidal tooth tool, and square tooth tool.
(6) Boring turning tool: used to turn drilled or cast holes. The purpose is to achieve photometric dimensions or truly straight hole surfaces.
(7) Side turning tool or side turning tool: used to turn the end face of the workpiece. The right turning tool is usually used at the end of the finishing turning shaft, and the left turning tool is used to finish turning the left side of the shoulder.
2. Different blade shapes are used due to different workpiece processing methods, which can generally be distinguished as:
(1) Right-hand turning tool: from right to left, turn the outer diameter of the workpiece.
(2) Left-hand turning tool: from left to right, turn the outer diameter of the workpiece.
(3) Round nose turning tool: The blade is arc-shaped and can be turned in the left and right directions. It is suitable for turning rounded corners or curved surfaces.
(4) Right turning tool: turning the right end face.
(5) Left turning tool: turning the left end face.
(6) Cutting knife: used for cutting or grooving.
(7) Inner hole turning tool: used for turning inner holes.
(8) External thread turning tool: used for turning external threads.
(9) Internal thread turning tool: used for turning internal threads.
4. Names and functions of each part of the turning tool
Turning tools are single-edged tools. They come in many types due to different shapes of the turning workpiece, but the names and functions of each part are the same. A good turning tool must have a rigid handle and a sharp blade. The blade angle of the turning tool directly affects the turning effect. Different turning tool materials and workpiece materials have different blade angles. Turning tools for lathes have four important angles, namely front clearance angle, side clearance angle, back bevel angle and side bevel angle.
1. Front clearance angle
The angle of inclination from the tool nose downward to the inside of the tool is the front clearance angle. Due to the front clearance angle, a space is formed under the working surface and the tool tip, so that the cutting action is concentrated on the tool nose. If the angle is too small, the tool will rub on the surface and produce a rough surface. If the angle is too large, the tool will easily vibrate, causing the tool nose to break and become impossible to polish. When installing a turning tool with an inclined center tool holder to grind the front clearance angle, the tool holder inclination angle needs to be considered. This angle is about 8 to 10 degrees for high-speed steel turning tools, and 6 to 8 degrees for carbide turning tools.
2. Side clearance angle
The angle at which the side of the knife inclines from the cutting edge to the inside of the knife is the edge clearance angle. The edge clearance angle forms a space between the work surface and the side of the tool, allowing the cutting action to be concentrated on the cutting edge, thereby improving cutting efficiency. The angle of high-speed steel turning tools is about 10 degrees to 12 degrees.
3.Rear bevel
The angle of inclination from the top surface of the knife from the nose to the handle is the back bevel. This angle is mainly used to guide chip removal and reduce chip removal resistance. For cutting general metals, high-speed steel turning tools generally have an inclination angle of 8 to 16 degrees, while carbide turning tools have a negative inclination angle or zero degrees.
4. Edge bevel
The top surface of the tool is inclined from the cutting edge to the other side, and the angle between this inclined surface and the horizontal plane is the edge bevel angle. This angle is the angle at which the chips are separated from the workpiece, making chip removal easy and achieving effective turning. The angle of high-speed steel turning tools is about 10 degrees to 14 degrees, while carbide turning tools can have positive or negative inclination angles.
5. Knife tip angle
The vertical angle between the front end of the blade and the handle. This angle is used to maintain a gap between the front end of the blade and the workpiece to prevent the blade from rubbing against the workpiece or scratching the machined surface.
6. Cut corners
The vertical angle between the front end of the blade and the handle is to change the thickness of the cutting layer. At the same time, the cutting angle can also change the force direction of the turning tool, reduce the cutting resistance, and increase the tool life. Therefore, in general rough turning, it is advisable to use a turning tool with a larger cutting angle to reduce the cutting resistance and increase the cutting speed.
7.Tool nose radius
The highest point of the blade is the radius of the blade arc. The tool nose radius is large and strong, and is used for large cutting depths, but it is prone to high-frequency vibration.
