Design, Fabrication and Application of Key-Tension-Tensionable Indexable Turning Tools

Design, Fabrication and Application of Key-Tension-Tensionable Indexable Turning Tools

1 Structural characteristics Cemented carbide indexable turning tool can be divided into lever type, insert bolt type, wedge type, pressure type, eccentric type, pull pad type, pressure hole type and so on. Among the commonly used types of indexable turning tools, some use positioning pins, because the positioning pins are susceptible to deformation, affecting the reliability of clamp positioning (such as wedge-type, etc.); some clamp positioning is reliable, but The structure is complicated and the manufacturing process is poor (such as lever type and plug type). The key-guided tension-adjustable turning tool has the advantages of reliable clamping positioning, convenient blade indexing and replacement, and good manufacturing process. Its structure is shown in Figure 1.

1
1. Knife pad 2. Blade 3. Key pin 4. Blade body 5. Spring washer 6. Nut Figure 1 Key-guided tension-type turning tool

This clamping structure has the following characteristics: 1 The principle of clamping the threaded bevel lever, the blade clamping force is large, reliable clamping; 2 due to the guiding role of the key pin, the knife pad can smoothly with the cutter body when subjected to force loading Together, it is not easy to produce cutting vibration, which increases the rigidity and cutting stability of the tool; 3 The blade is easy to change indexing and replacement (just adjust the tail nut); 4 head body is small. 2 Design points When designing SNU U160602FR inserts with key-lead-oriented tightenable indexable turning tools, the main declination angle kr can be 45°, 60°, 75°, 90° (usually kr=75°); Required cutting angle, optional rake angle gog=-8°～-15°, slash angle range lsg=0°～10° (common lsg=0°); tool nose angle erg =80° to 90° (usually erg=90°); the main angling angle of the sipe is krg=45° to 90°. The accuracy of the key-ring flat key part keyway and knife pad is H9/h9; the precision of the key-key flat key part and the key slot in the knife slot on the knife head body is D10/h9 (or F7/h6); the key pin The fitting accuracy of the hook cylindrical surface and the blade hole is C11/h11 (or B12/h12); the dynamic matching accuracy of the cylinder surface and the outer diameter portion of the key pin tail screw and the round body of the cutter body is B12/h12 . By adjusting the relative movement of the tail screws and nuts, the blades can be clamped and released at any time to achieve rapid indexing and replacement of the blades. In order to make the tightened blade close to the two right-angled positioning base surfaces of the sipe on the cutter head body, no looseness will occur due to the cutting vibration, and a spring washer is added between the nut and the end surface of the cutter head body. 3 Manufacturing points The tool head body of the cutter body is 45 steel. Blanks must be forged to improve the internal structural toughness of the material. Heat treatment hardness should be controlled at 38 ~ 42HRC. If the hardness is too high, the cutter head body is easily cracked under the action of the cutting load; if the hardness is too low, the cutter head body is insufficient in rigidity, and the flank surface part is easy to generate a depression under the action of the C-shaped chip, thereby weakening the cutter body. The support strength of the blade may even cause knife-cutting in severe cases. The sipes on the cutter body are milled. In order to ensure that the position of the keyway on the plane of the sipe is perpendicular to the two right angles, the bottom surface of the sipe and the two right-angle positioning bases in contact with the cutter body can be processed at one time. The machine tool itself ensures the required verticality and parallelism of the keyway on the cutter head body. The key pins for processing key pins are the key parts that can withstand the cutting load and should be made of 40Cr steel (tempered and tempered) or 45 steel (hardened 35 to 38HRC). The heat treatment hardness of the parts should be reasonably controlled, both to ensure the strength of the end of the hook and the wear resistance of the tail thread, but also to make the key pins have good toughness, not easy to break. The precision of the key pin size processing is higher, and the surface roughness of the processing should be Ra1.6-3.2 μm. In order to ensure the stability and reliability of the blade clamping, the point of contact of the cylindrical surface of the key pin with the blade hole should be higher than 1/2 to 2/3 of the thickness of the blade. For this purpose, the lower root of the cylinder of the key pin hook should be ground 0.2 to 0.4 mm on the tool grinder to ensure that the upper part of the cylinder is in reliable contact with the blade hole. The tool pad material of the pad is made of 40Cr steel (tempered and tempered) or 45 steel (normalized). In order to ensure the close fit of the blade and the sipe plane, the parallelism of both ends is required to be 0.01-0.03mm, and the surface roughness is Ra6.3-3.2μm. 4 Application points Selection of cutting amount Roughing: When roughing, in order to improve the tool durability and productivity, the maximum allowable depth of cut ap should be determined first, and then a larger feed amount f is selected according to the blade strength and the bearing capacity of the machine, and finally The appropriate cutting speed v is determined under the power allowable condition of the machine. For deep-cut rough machining, if the width of the chipbreaker for indexable inserts is narrow, chipping and poor chipping are likely to occur, and even chipping occurs (usually at a depth of 2/3 of the tool tip). Department). Therefore, when roughing steel parts, factors such as the width of the insert groove should be taken into consideration, and the amount of cutting should be modified appropriately. Finishing car: When finishing a car, a large rake angle insert with a chip breaking groove should be used to increase the sharpness of the cutting edge and reduce the cutting force. Since the quality of the workpiece surface (including geometrical dimensions and surface roughness) is a major consideration in finish turning, high cutting speeds should be used as much as possible, and cutting depth ap and feed amount f should be reduced, but the cutting layer The thickness should not be less than 0.05mm, otherwise the surface hardening phenomenon will easily occur, affecting the surface quality of the workpiece and reducing the tool durability. Table 1 shows the reference cutting amounts available for processing different materials. Precautions for Use When processing low-carbon steels, stainless steels and other materials with better plasticity and toughness, it is better to use single-sided, positive-quadrant inserts with chip breakers with good chipping effect. Table cutting speed available when processing different materials Workpiece materials Workpiece heat treatment conditions ap = 0.2 ~ 2mm
f=0.06 to 0.2mm/r ap=2 to 5mm
f=0.2 to 0.5mm/r ap=5 to 8mm
f=0.5-0.8mm/rv(m/min) v(m/min) v(m/min) Hot rolling of low carbon steel 110-150 90-110 80-90 Hot rolling of medium carbon steel 100-120 80-100 70～90 Conditioning 80～100 70～90 60～80 Quenching 50～70 40～60 - Hot-rolled alloy steel structure steel 80～100 70～90 40～70 Conditioning 70～90 50～80 40～50 Stainless steel 170 ～180HB 60～80 50～70 40～50 Gray cast iron<190HB 70～100 60～70 50～70 190～220HB 70～90 50～70 40～60 When inserting the insert, ensure that the underside of the insert is in close contact with the knife pad The two sides of the blade are in close contact with the two right-angled positioning bases of the cutter body sipe to prevent the blade from vibrating due to blade vibration. In order to improve the processing efficiency, when the normal blade wear reaches VB=0.3mm, the blade should be indexed or replaced in time. The tool is used for machining hardened steel, gray cast iron, etc. By changing the tool tip geometry, the clamping structure can also be applied to triangular (60°) thread turning tools as well as boring and milling tools.

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