JPH05162B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a throw-away tip suitable for use in a cutting tool such as a face mill, and particularly to a throw-away tip suitable for use in cutting of steel, cast iron, etc. [Prior art] Conventionally, for example, in a throw-away tip (hereinafter sometimes abbreviated as a tip) used for a face milling cutter, the strength of the cutting edge is generally high because the face milling cutter performs interrupted cutting. Being something is important. Therefore, as tips used for such cutters, negative tips are used in which the angle between the rake surface and the side surface (flank surface) is a right angle. [Problems to be solved by the invention] However, in the case of negative chips,
Despite the high strength of the cutting edge, there were problems such as a relatively large number of chippings of the cutting edge. In other words, when cutting with a negative chip, the chip is used so that its rake angle is a negative value, which generates a large amount of cutting heat and produces thick chips. .
A large amount of cutting heat softens the cutting edge of the chip. On the other hand, since the rake angle of the chip is negative, the chips collide with the rake face of the chip with a large pressing force, and the flow direction of the chips is abruptly changed. At this time, the chips scrape off a large amount of the rake surface of the chip due to frictional force. This amount of scraping is further facilitated because the cutting edge portion of the chip is softened by the cutting heat. As a result, many craters are formed on the rake face of the chip at an early stage. On the wall surface defining this crater, there are many streaks extending along the direction of outflow of chips. Then, cracks occur from the streaks due to the impact load caused by interrupted cutting, the pressing force caused by chips, etc., and this leads to a situation where the chip breaks. Further, in negative chips, there is a problem in that the cutting edge portion is softened by a large amount of cutting heat, resulting in large flank wear. Because of this large flank wear and the problem of chipping mentioned above, the chip life was very short. The shortened lifespan of chips has lowered the operating rate of machine tools such as machining centers to which face milling cutters and the like are attached. However, machining centers are very expensive, and there has been a desire to extend the lifespan of the chips in order to improve their operating efficiency. Furthermore, in the case of negative chips, cutting resistance increases because the rake angle is negative, so even if high-precision machine tools such as machining centers are used, machining accuracy cannot be improved beyond a certain limit. There was a problem. [Purpose of the Invention] This invention was made to solve the various problems mentioned above, and can significantly reduce chipping of the cutting edge portion and flank wear, thereby extending the life of the chip. An object of the present invention is to provide a throw-away tip that can reduce cutting resistance. [Process leading up to the invention] The inventor presumes that the main cause of the above problem is that the rake angle is negative, and conducted a cutting test by attaching a standard positive tip to a face milling cutter. I went. However, the expected effect was hardly achieved. Therefore, although this is completely contrary to conventional technical common sense, we created a positive tape with a clearance angle of 30° to 45° and attached it to a face milling cutter with a rake angle of 20° to 35°. As a result, since the strength of the cutting edge was low, chipping occurred at an early stage, and the chipping progressed to chipping, so that it was hardly usable. However, it has been found that if the cutting edge portion is honed, chipping due to a decrease in the strength of the cutting edge and resulting chipping can be prevented. Moreover, since the rake angle is large at 20° to 35°, it was possible to significantly reduce cutting heat and cutting resistance. [Structure of the Invention] Based on the above knowledge, this invention sets the clearance angle of the flank face to 35° to 45°, hones the intersection of the flank face and the rake face, and sets the honing width to 0.1 mm0. The structural feature is that the honing angle is .2mm and the honing angle with respect to the rake face is set at 30° to 45°, or the radius of curvature is round honing with a radius of 0.05mm to 0.1mm. It is something. [Examples] Examples of the present invention will be described below with reference to the accompanying drawings. FIG. 1A and FIGS. 2A and 2B show an embodiment of the present invention. Throwaway tip A shown in these figures is made of cemented carbide or cermet, and is formed into a flat plate that is approximately square in plan view, with the upper surface serving as the rake surface 1 and the lower surface serving as the chip. It serves as a mounting surface 2 for mounting on a seat. The side surface existing between the rake surface 1 and the mounting surface 2 is a flank surface 3. A cutting edge 4 is formed at the intersection of the flank surface 3 and the rake surface 1. This cutting edge 4 has a main cutting edge 4a because the tip A is used for face milling.
and a auxiliary cutting edge 4b. As will be described later, since honing 5 is applied to the intersection between the rake face 1 and the flank face 3, the cutting edge defined as the intersection line between the rake face and the flank face in chip A is It is becoming impossible to clearly exist. The above structure is similar to that of the conventional chip, but in the chip A according to the present invention, the clearance angle TN of the flank surface 3 is set to 30° to 45°. Therefore, when using Chip A, if the normally required true clearance angle of 7° to 10° is secured, depending on the size of the clearance angle set in practical use,
The rake angle can be approximately 20° to 35°. Here, if the above clearance angle is less than 30°, if the true clearance angle is secured at about 7° to 10°,
If the rake angle is less than 20°, the cutting force will become excessive. Conversely, if the rake angle is increased to 20° or more in an attempt to reduce the cutting force, the required true clearance angle (7° to
(approximately 10°), which increases flank wear and is inappropriate. On the other hand, if the clearance angle exceeds 45°, the cutting edge angle of the chip becomes too small, and even after honing, which will be described later, is performed, the chip still tends to chip and is unsuitable for use.
For this reason, the above clearance angle should be set to 30° or 45°.
It was set to . By the way, if the clearance angle TN is set to 30° to 45°, the strength of the cutting edge portion decreases as described above, making it impossible to put it to practical use. Therefore, in the chip A, as shown in FIG. 1A, angle honing 5 is applied to the main cutting edge 4a of the intersection between the rake face 1 and the flank face 3. This honing 5
The width W along the rake face 1 is set to 0.1 mm to 0.2 mm. This means that the honing width W is 0.1
This is because if it is smaller than mm, the strength of the cutting edge portion cannot be sufficiently improved, and if it is larger than 0.2 mm, the increase in cutting resistance cannot be ignored. In addition, the honing angle HN is determined by the honing angle HN when the rake angle of rake face 1 is set to 20° to 35°.
so that the rake angle is around -10°.
It is set at 45°. In addition, the above honing angle
If HN is less than 30°, the honing width cannot be controlled with precision, and the honing width will become too small, resulting in chipping of the cutting edge.On the other hand, if the above angle HN exceeds 45° and,
Both methods are unsuitable because the cutting resistance increases. Note that the honing applied to the intersection of the rake face 1 and the rake face 3 may be a round honing 6 as shown in FIG. 1B. In this case, the radius of curvature R of the round honing 6 needs to be set to 0.05 mm to 0.1 mm. The radius of curvature of the above round honing is
If the radius of curvature is less than 0.05 mm, the cutting edge will break. On the other hand, if the radius of curvature exceeds 0.1 mm, although the strength of the cutting edge will increase, it becomes difficult to process such a large radius of curvature. This is because it is not the target. Also, regarding these honing,
As shown in FIG. 1C, a composite honing 7 may be used in which the intersections of each end of the honing 5 shown in FIG. 1A and the rake face 1 or flank face 3 are smoothly connected by an arc. On the other hand, regarding the sub-cutting edge 4b portion of the intersection between the rake face 1 and the flank face 3, since the cutting load acting on the sub-cutting edge 4b portion is small, honing is not necessary. When performing honing,
It is preferable that the honing has the same shape as the honing applied to the main cutting edge 4a, and is about the same size or slightly smaller. FIG. 5 shows a face milling cutter in which a plurality of tips A having the above configuration are attached in the circumferential direction to the tip of the cutter body D, and the tips A have a true rake angle T of the main cutting edge 3a of 20. The cutter body D is attached to the cutter body D with the true angle CN set at around 10 degrees. When cutting with such a face mill, even if the required true clearance angle of about 7° to 10° is secured, the rake angle, which conventionally had a negative value, is 20°.
Since the angle is between 35° and 35°, the generation of cutting heat can be significantly reduced. Therefore, softening of the cutting edge portion can be significantly suppressed. Also,
The generated chips are thinner, and since the chips do not collide with the rake face 1 with a large pressing force and change their flow direction suddenly, the occurrence of craters is greatly reduced, and craters are prevented. The occurrence of streaks on the wall surface defining the area is prevented. By suppressing the softening of the cutting edge portion and preventing the generation of craters and accompanying streaks, chipping of the cutting edge portion can be prevented. Moreover, since honing 5 is applied to the intersection of the rake face 1 and the rake face, the strength of the cutting edge part is improved. Chipping that occurs when the angle T is set at 20° to 35° and the resulting defects can also be prevented. Furthermore, since less cutting heat is generated and softening of the cutting edge portion can be suppressed, flank wear is significantly reduced. This reduction in flank wear and prevention of breakage work together to improve the life of the chip A. Furthermore, since cutting resistance can be reduced, deformation of the workpiece, vibration of the cutter and the workpiece, etc. can be reduced, and the performance of high-precision machine tools such as machining centers can be fully demonstrated.
It is possible to improve processing accuracy. [Example] Next, the results of tests conducted to confirm the effects of the above-mentioned Chip A according to the present invention will be introduced. In this test, the relief angles were 10°, 20°,
We prepared four types of tips, 30° and 40°, and attached each tip to the cutter body in a single blade state, each with a 10° angle.
It was installed with a true relief angle of . Therefore, the true rake angles for these four types of chips are 0°, 10°, 20°, and 30°, respectively. Further, the honing amount is 0.2 mm and the honing angle is 30 degrees.
Note that the other cutting edge angles were the same. The cutting conditions are as follows. Work material SCM440 (HB240) Cutting speed 160m/min Feeding amount 3mm Feed amount 0.4mm/rev Total cutting amount 2600mm Room temperature 25℃ The test results are shown in the table below. In the table, the components of cutting resistance X, Y, and Z are as shown in FIG. Furthermore, the cutting heat was changed by measuring the temperature of the workpiece. In the section of cutting heat, instantaneous heat refers to the temperature of the workpiece at the moment the cutting edge approaches the temperature measuring device, and residual heat refers to the temperature of the workpiece while the cutting edge is away from the workpiece. be.

[Table] Next, the table below shows an experimental example in which we investigated how the angle honing width affects cutting. The relief angles of the chips shown in the experimental examples are all
The width and angle in Table 2 are all related to honing. The work material was 100 mm wide and 200 mm long, and in each case, 5 sides were cut. Other cutting conditions are the same as in Table 1.

【table】

[Table] According to Table 2, if the honing width is 0.05 mm or less, as in chips No. 1 and No. 2, chipping and chipping will occur. This is because the part of the chip that first hits the workpiece is closer to the tip of the cutting edge (the ridgeline where the flank and honing surfaces intersect). No chipping was observed when the honing width was 0.1 mm or more, as in the case of No. 3 chip. This is because the part of the chip that first hits the workpiece is far from the tip of the cutting blade, and is the ridge line where the rake face and honing face of the cutting blade intersect. However, when the honing width is 0.25 mm or more, as with the No. 5 chip, chipping and chipping do not occur, but the thrust force in the thrust direction (Z direction in Figure 6) of the cutting resistance increases. To,
The wear amount of the chip is also large, and the cutting heat is also large, which deteriorates the finished surface of the workpiece. Figure 8 shows the thrust forces of chips No. 4, No. 5, and No. 6 in the above table. As you can see from this figure 8,
Compared to chip No. 4, which is an embodiment of the present invention,
It can be seen that as the feed rate increases, the thrust force becomes significantly larger for chips No. 5 and No. 6. Next, Table 3 shows an experimental example of how the curvature of round honing affects cutting. In addition, the round honed material was cut on five sides under the following conditions in order to obtain a cast material. Work material FC25 Cutting speed 120m/min Feeding amount 3mm Feed rate 0.3mm/rev Total cutting amount Cutting a plate material of 10mm x 200mm in the length direction Room temperature 25℃ Chip relief angle 30°

[Other Examples]

Next, other embodiments of the invention will be described. The chip B shown in FIGS. 3A and 3B is formed into a substantially triangular shape in plan view, and the corner portion 4b is formed by an arc. Moreover, the chip C shown in FIGS. 4A and 4B is formed into a circular shape in plan view. Incidentally, in these chips B and C, the same parts as those in the above-mentioned chip A are given the same reference numerals. [Effects of the Invention] As explained above, according to the throw-away chip of the present invention, the relief angle of the flank face can be set to 30° or more.
Since the rake angle is set to 45°, the rake angle can be set to 20° to 35° when the chip is used for actual cutting. Therefore, chipping of the cutting edge portion caused by crater wear and flank wear caused by cutting heat can be significantly reduced, and the life of the chip can be greatly improved.
In addition, cutting resistance can be reduced, so
It is possible to improve processing accuracy. Moreover, the intersection of the rake face and flank face is honed,
Since the honing width is 0.1 mm to 0.2 mm and the honing angle with respect to the rake face is set to 30° to 45°, the honing method is angular honing, or the radius of curvature is 0.05 mm to 0.1 mm. By setting the relief angle to 30° to 45°, chipping and associated damage can be prevented, and other effects can be obtained.

[Brief explanation of the drawing]

1A, B, and C are views showing essential parts of the throw-away tip according to the present invention, and are enlarged cross-sectional views taken along the - line in FIG. 2A, FIGS.
The figures each show an embodiment of the present invention, in which Figure A is a plan view, Figure B is a side view, Figure 5 shows a face milling cutter to which the throw-away tip shown in Figure 2 is attached, and Figure 5 A is a longitudinal cross-sectional view, FIG. 5B is a diagram showing the rake angle and relief angle of the main cutting edge, FIG. 6 is a diagram showing the three components of cutting resistance, and FIGS. 7A, B, C, and D. are the relief angles, respectively.
A diagram showing the wear conditions when the angles are 10°, 20°, 30°, and 40°, and FIG. 8 is a diagram showing the thrust force. A, B, C... Throwaway tip, 1...
Rake surface (top surface), 2... Placement surface (bottom surface), 3...
Relief surface (side surface), 5, 6, 7...Honing.

Claims (1)

[Claims] 1. In a throw-away tip that has a flat plate shape as a whole and has a relief surface between an upper surface serving as a rake surface and a lower surface serving as a mounting surface, and is used for cutting ferrous metals such as steel and cast iron, The clearance angle of the flank face is set to 30° to 15°, and the intersection of the rake face and flank face is honed, and the honing width is 0.1 mm to 0.2 mm.
and the honing angle to the rake face is 30°.
or angle honing set to 45°,
Or a throw-away tip characterized by round honing with a radius of curvature of 0.05mm to 0.1mm.