The development of modern manufacturing technology and the widespread use of numerical control equipment have greatly promoted the advancement of cutting technology. With the need for numerical control and automation, higher requirements for high reliability, high precision, long life, fast index change, and good chip breaking are proposed for metal cutting tools. The design of the pool structure and the shape of the cutting part have become very numerous, which makes it difficult for the machine and tool designers to select the tool reasonably. Selecting the required tool according to different characteristics is of great importance for achieving highly automated cutting. Here is a brief introduction to how to choose the angle of the metal cutting tool:
First, the requirements for tool materials
(1) higher hardness. Its hardness should be greater than the hardness of the workpiece material.
(2) Good wears resistance. Increase tool time and increase efficiency.
(3) sufficient strength and toughness. To ensure sufficient resistance to cutting resistance, impact and vibration.
(4) High heat resistance. It can maintain the hardness, wear resistance, strength and toughness required for cutting at elevated temperatures.
Second, commonly used tool materials
(1) alloy tool steel. It has superior heat hardness but is inexpensive, and is often used to make low-speed tools with complex shapes such as reamer, tap and die.
(2) high speed tool steel. Its high temperature hardness and wear resistance are preferable to alloy tool steel. Due to its excellent heat treatment performance, high strength and good sharpness, it is widely used in the manufacture of various machine tools such as forming turning tools, milling cutters, drill bits and broaches.
(3) cemented carbide. It is just an alloy made by powder metallurgy of materials such as tungsten carbide, titanium carbide and cobalt. Carbide inserts are usually employed on the body of the tool. Currently, cemented carbide has been one of the main tool materials.
Third, the geometry of the tool
The geometry of the tool mainly refers to the geometry of the cutting part, understanding the composition of the cutting part, the auxiliary plane, the geometric angle of the cutting part and so on.
(1) Front. The surface that the first contact is when the chips flow out. In order to curl and exit the chips, the front side of the tool is generally ground with chipbreakers when cutting the plastic material. The front can be to a flat surface or a curved surface.
(2) the main flanks. The surface of the pool that faces the cutting surface of the workpiece during cutting.
(3) Vice flanks. When cutting, the surface of the pool opposite the finished surface of the workpiece.
(4) main cutting edges. The intersection of the front and the main flank, it is responsible for the highest cutting task.
(5) Sub cutting edge. The intersection of the front and the flank face is only responsible for a small number of cutting tasks.
(6) The tip of the knife. The intersection of the main cutting edge and the minor cutting edge. To enhance the strength and wear resistance of the tip, the tip is often ground into a small vertical line or arc.
Fourth, the geometric angle of the turning tool
(1) front angle. It reflects the degree of tilt in front, and the sharper the opposite angle, the sharper the sharper the cut. However, the visible corner assembly reduces the strength of the cutter head portion and is prone to chipping during the cutting process.
(2) back corners. The principal function of the back angle is to reduce the friction between the tool and the machined surface, but it will reduce the heat dissipation of the cutter head.
(3) wedge angle. The angle between the front and the main flank.
(4) leading angle. It determines the length of the core cutter, the strength of the tip and the radial force. When the mean declination is small, the cutting width is increased and the cutting thickness is reduced. The length of the main cutter increases the tool wear and becomes less durable. However, it is not difficult to cause vibration to increase the radial force, and the bending of the elongated workpiece affects the accuracy.
(5) Vice declination. It decreases the friction between the secondary cutting edge and the finished surface.
(6) The corner of the knife. It takes into account the strength and heat dissipation of the tip.
(7) Blade inclination. It mainly influences the strength of the cutter head and the direction of the chip removal to change the force of the cutter head. In the rough work, the negative value is often taken with a view to increase the strength of the cutter head. In the stormy work, the surface is taken to a positive value in order not to scratch the chip.
Five, cutting oil selection considerations
Cutting oil is a kind of medium that must be used in the metal cutting process. It mainly acts as lubrication, cooling and cleaning in the process.
(1) special cutting oil contains vulcanized extreme pressure anti-wear additive component, which can effectively protect the tool and improve the process precision.
(2) The special cutting oil has superior stability compared with rapeseed oil, mechanical oil and reclaimed oil, and will not cause harm to equipment, human body and environment.
(3) The special cutting oil has passed rigorous tests in terms of viscosity. Flash point, pour point and thermal conductivity to meet various cutting process requirements.