JP2007083381A - Throw away insert and rotary cutting tool having the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a throw away insert capable of being used in a heavy duty cutting having a severer cutting condition by reducing cutting resistance without deteriorating the strength of a cutting edge. <P>SOLUTION: The throw away insert 1 comprises a plurality of first divided main cutting edges 5A divided by a main groove part 6 having a main cutting edge 5 on the flank 4 formed in approximately polygonal plate shapes, having a cutting face 3 on an upper surface, a seating surface 2 on a lower surface, a flank 4 on a side surface, and the main cutting edge 5 formed at a crossed ridge parts between the cutting face 3 and the flank 4. The throw away insert 1 has a sub groove part 6 further dividing the first divided main cutting edge 5A and forming a plurality of the second divided main cutting edge 5a. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a throw-away insert used for a turning tool such as a face mill or an end mill.

As a throw-away insert used in conventional milling tools such as face mills and end mills, especially those with long cutting edges and a large number of cutting edges attached, the rake face continuous from the main cutting edge is positive. A throwaway insert having a corner and having a flank including a main cutting edge divided by a groove is known (for example, Patent Document 1). Such a throw-away insert is mainly used for cutting such as heavy cutting where a large amount of chips are discharged, and has a large cutting resistance at the time of cutting, but the main cutting edge is formed by forming a groove. Are divided, and the width of the generated chip is divided into small pieces. As a result, the cutting resistance is reduced and the biting property to the work material is improved, so that an effect of suppressing chatter vibration during machining can be obtained.
JP 7-299636 A

  However, as a recent trend in the machining industry, in order to further increase the efficiency of cutting work, heavy cutting with a particularly large depth of cut tends to be performed. In heavy cutting under such severer cutting conditions, large deflections are inevitably generated and cutting resistance increases, so even with the above-configured throw-away insert, it is not possible to suppress the occurrence of chatter vibration. It was not always enough.

    In order to further suppress chatter vibration in such heavy cutting, etc., it is effective to reduce the cutting resistance by increasing the number of grooves that divide the flank including the main cutting edge. In this case, since the strength of the divided cutting edge portion is greatly reduced, there is a problem that the throw-away insert is easily lost.

  The present invention has been made to solve the above-described problems of the prior art, and is a throw-away insert used in a turning tool, particularly a turning tool having a long cutting edge length and a large number of cutting edges attached thereto. The purpose is to provide a highly reliable throw-away insert that can reduce cutting resistance without greatly reducing the cutting edge strength and suppress chatter vibration even in heavy cutting under severer cutting conditions. And

  In order to solve the above problems, a throw-away insert according to the present invention is formed on a rake face formed on the upper surface of a substantially plate-shaped main body, a seating surface formed on the lower surface of the main body, and a side surface of the main body. A flank, a main cutting edge formed at a crossing ridge line portion between the rake surface and the flank, and a main groove formed on the flank and having both ends reaching the seating surface and the rake surface. The main cutting edge and the flank face are each composed of a plurality of first divided main cutting edges and divided flank faces divided by the main groove portion, and further the first divided main cutting edge. Is arranged on the divided flank side by side with the main groove portion so that one end reaches the rake face, and is divided into a plurality of second divided main portions divided by sub-groove portions having a width smaller than the width of the main groove portion. Consisting of cutting edges It is characterized by a door.

With such a configuration, the first divided main cutting edge divided by the main groove portion is further divided into a plurality of second divided main cutting edges by the sub-groove portion whose one end reaches the rake face, and the cutting edge strength is increased. It is also possible to reduce the cutting resistance accompanying the reduction of the contact surface between the insert and the work material while suppressing the decrease of the cutting force. As a result, chatter vibration during machining can be suppressed, and heavy cutting with severer cutting conditions can be performed. In addition, since the width of the generated chip is further reduced corresponding to the length of the second divided main cutting edge, the chip discharging property is improved and the chip is not trapped. In addition, since the large reduction in the cutting edge strength and the chipping, chipping, breakage, etc. of the cutting edge caused by inserts with a large number of main grooves are formed, the life of the insert is extended. Further, the fact that the length of the sub-groove portion is shorter than the thickness of the main body portion, even if the flank formed between the two main groove portions is divided into a plurality by the sub-groove portion, The plurality of divided flank faces are continuous on the bottom surface side, so the strength is high, and it is possible to prevent the flank face part sandwiched between the two main groove parts or the flank face part sandwiched between the sub groove part and the main groove part from being lost. As a result, the cutting edge strength can be improved, which is desirable.

  Further, the depth of the sub-groove portion is smaller than the depth of the main groove portion, and the rake face portion sandwiched between the two main groove portions or the rake face portion sandwiched between the sub-groove portion and the main groove portion is missing. Can be prevented and the cutting edge strength can be improved, maintaining a good balance between maintaining the cutting edge strength and reducing cutting resistance, enabling heavy cutting such as increasing the amount of cutting during cutting. This is desirable.

  Further, the depth of the main groove portion and the sub-groove portion is larger than a preset maximum feed amount per one cutting tool, so that chips are surely divided and cutting resistance can be reduced. desirable.

  Furthermore, it is desirable that the width of the sub-groove portion is 1/6 to 5/6 of the width of the main groove portion because a reduction in cutting resistance and maintenance of cutting edge strength can be achieved in a well-balanced manner.

  Further, the sub-groove portion is arranged so as to divide the first divided main cutting edge substantially equally, and the first divided main cutting edge is equally divided by one end of the sub-groove portion reaching the rake face. Since the processing load applied to each of the first divided main cutting edges is equally distributed, it is desirable because cutting resistance can be reduced in a well-balanced manner and reduction in cutting edge strength can be suppressed to the maximum.

  Further, each chip formed with a narrow width by each of the second divided main cutting edges is provided with at least one protrusion corresponding to the second divided main cutting edge on the rake face. However, it is desirable that the chip is improved in terms of chip discharge because it contacts the corresponding protrusion and is efficiently bent and deformed.

  In addition, a screw hole penetrating to the seating surface is provided at the center of the rake face, and an annular raised portion is provided around the screw hole so that the chip curling action by the protrusion is insufficient. However, it is desirable because curling of the chip can be promoted and wear of the clamp screw head due to the collision of the chip can be prevented.

  Furthermore, the rolling tool having the throw-away insert and a tip holder for mounting a plurality of the throw-away inserts improves the discharge performance by subdividing the chips, and the throw-away insert and the holder. This is desirable because the number of replacements can be reduced and the production efficiency can be improved by suppressing the chipping and wear of the metal and extending the respective lifetimes.

  Further, the main groove portion and the sub groove portion are formed along the circumferential direction around the axis of the chip holder, and the portion where the work material is left uncut between the divided cutting edges is formed on the insert side surface portion. This is desirable because it prevents the uncut portion from coming into contact with the side surface portion of the insert, thereby preventing chatter vibration.

  According to the throw-away insert of the present invention, since the first divided main cutting edge is further divided by the sub-groove portion, the contact surface between the insert and the work material can be reduced while suppressing a reduction in the cutting edge strength. The accompanying cutting force can also be reduced. As a result, chatter vibration during machining can be suppressed, and heavy cutting with severer cutting conditions can be performed. In addition, since the width of the generated chip is further reduced corresponding to the length of the second divided main cutting edge, the chip discharging property is improved and the chip is not trapped.

  Embodiments of the present invention will be described below with reference to the accompanying drawings.

  1 and 2 and FIGS. 5 to 8 show an embodiment of the present invention. FIG. 1 shows an entire throw-away insert (hereinafter abbreviated as an insert) 1 according to a first embodiment of the present invention. 2A is a plan view of the insert 1 of FIG. 1, FIG. 2B is a side view of the long side, FIG. 5C is a side view of the short side, and FIG. ) Plan view, (b) Long side side view, (c) Short side side view, FIGS. 6 to 8 are perspective views of the inserts 31, 41 and 51 according to the third, fourth and fifth embodiments. It is. FIG. 3 is an overall perspective view of the rolling tool using the insert of the present invention, and FIG. 9 is an enlarged perspective view showing a mounting state of the insert 41 of the rolling tool of the present invention. 4A to 4D are simplified views of the cutting edge shapes of various inserts used in the cutting performance evaluation experiment of the insert of this embodiment.

  1 and 2, the insert 1 according to the first embodiment is composed of a substantially polygonal main body, and includes a seating surface 2 on the lower surface of the main body, a rake surface 3 on the upper surface, and a relief surface 4 on the side surface. ing. And the main cutting edge 5 is formed in the intersection ridgeline part of the rake face 3 and the flank 4.

  Here, the flank 4 is formed with a main groove 6 whose both ends reach the rake face 3 and the seating surface 2, and the main cutting edge 5 and the flank 4 are each divided into a plurality of parts separated by the main groove 6. It is constituted by the first divided main cutting edge 5A and the divided flank 4A. Furthermore, on the divided flank 4A, a sub-groove portion 7 is arranged side by side with the main groove portion 6 so that one end thereof reaches the rake face 3. Specifically, the sub-groove portion 7 is formed between two main groove portions adjacent to each other in the insert longitudinal direction and between the main groove portion 6 and the insert longitudinal direction end surface portion. The first divided main cutting edge 5 </ b> A is constituted by a plurality of second divided main cutting edges 5 a divided by one end of the sub-groove portion 7.

  In FIG. 3, the perspective view of the rolling tool 11 which mounted | wore with the insert 1 of this invention is shown. Here, a plurality of chip pockets 13 are formed at the outer peripheral tip of the holder 12, and the insert 1 is attached to each outer peripheral position in the chip pocket 13. Specifically, the insert 1 is mounted such that the main cutting edge 5 is positioned on the outermost periphery with the rake face 3 facing in the rotation direction, and the main cutting edge 5 rotates together with the holder 12 to perform cutting.

  Generally, when cutting with such a rolling tool, bending stress acts on the holder, but the holder has a certain rigidity so that large bending does not occur due to such bending stress. Yes. However, in actual cutting, the magnitude of the bending stress acting on the holder changes depending on the processing conditions, etc., so when the processing load is large, a large deflection occurs due to insufficient rigidity of the holder. As a result, chatter vibration during processing may be induced. In particular, in heavy cutting with a large depth of cut, chatter vibration is likely to occur because the cutting resistance is remarkably increased.

  Therefore, conventionally, in the above rolling tools, as a means for reducing the cutting resistance, a combination of a plurality of inserts in which the flank surface including the main cutting edge is divided by a groove that reaches both the rake surface and the seating surface. Have been widely used. That is, in such an insert, since the width of the generated chip is divided into small parts, chatter vibration during processing is suppressed by reducing the cutting resistance. However, in order to enable heavy cutting under severer cutting conditions, simply increasing the number of grooves with the same shape as before, the strength of the cutting edge divided by the grooves will decrease, and chipping and Since defects and the like are likely to occur, there is a limit to reducing cutting resistance.

  In contrast, in the insert 1 according to the first embodiment of the present invention as shown in FIGS. 1 and 2, the larger main groove portion 6 having a conventional shape for dividing the flank 4 including the main cutting edge 5 is: In order to further reduce the cutting resistance, the first divided main cutting edge 5A is further divided by a smaller sub-groove portion 7 so that the cutting edge strength can be maintained. By setting it as such a structure, cutting resistance is reduced, without the intensity | strength of a cutting edge part falling significantly. As a result, chatter vibration can be suppressed without causing any chipping in the insert 1 even in heavy cutting with a large depth of cut.

  In this embodiment, since the 1st division | segmentation main cutting edge is further parted by the subgroove part 7, while being able to reduce the cutting resistance concerning a main cutting edge part, the subgroove part 7 is formed smaller than the main groove part 6. FIG. Thereby, the big strength fall of the cutting edge part seen in the case of formation of the main groove part 6 is suppressed. That is, the coexistence of the main groove portion 6 and the sub groove portion 7 makes it possible to reduce the cutting resistance accompanying the reduction in the contact surface between the insert 1 and the work material while suppressing the reduction in the cutting edge strength. As a result, chatter vibration during machining can be suppressed, and heavy cutting with severe cutting conditions can be performed.

Further, in the present embodiment, the first divided main cutting edge divided by the main groove 6 is further divided into a plurality of second divided main cutting edges by the sub-groove part 7, so that the generated chip width is Since the length substantially coincides with the length of the second divided main cutting edge, the chip becomes lighter. Thereby, in the cutting process using the rolling tool 11 shown in FIG. 3, chips are easily discharged from the chip pocket 13 formed in the holder 12, and the chip discharge property can be improved. Accordingly, problems such as chip clogging and chip biting in the chip pocket 13 are suppressed, and the insert 1 and the holder 12 can be used over a long period of time. As a result, the number of replacements of the insert 1 can be reduced, and the production efficiency can be improved. Further, since the chips discharged outward from the chip pocket 13 are lightweight, they move without being accumulated around the work material. Therefore, it is possible to prevent the work material from being damaged by chips. As a result, the accumulation of chips on the periphery of the work material is suppressed, so that the biting of chips into the cutting edge is also reduced. In this way, chip discharge performance at the heavy-cutting mounting leg is improved.

  In the present embodiment, the sub-groove portion 7 is formed at the end portion of the insert 1 in the width direction, immerses in the insert width direction from the end surface in the width direction, and extends from the rake face 3 of the insert 1 in the insert thickness direction. Further, the sub-groove portion 7 is formed to have a smaller immersion amount, that is, a depth, into the insert 1 than the main groove portion 6.

  Furthermore, the dimension in the insert width direction of the main groove portion 6 and the sub groove portion 7 is set to be larger than at least the preset maximum feed amount per blade of the rolling tool 12. In the present embodiment, the dimension in the insert width direction of the main groove 6 is set to a dimension in which the reduction in cutting resistance becomes critical, and the dimension in the insert width direction of the sub-groove 7 is set to the maximum value of the expected feed amount. Is set. Further, the dimensions of the main groove 6 in the insert longitudinal direction, the insert width direction, and the insert thickness direction are set to dimensions necessary for maintaining the strength of the insert 1.

  1 and 2 exemplify an embodiment in which three main groove portions 6 are formed. However, the larger main groove portion 6 having a conventional shape that divides the flank 4 including the main cutting edge 5 maintains the cutting edge strength. The shape, arrangement, and number are selected as much as possible.

  In the present embodiment, since the clearance angle is set in the insert 1, the clearance surface 4 increases inward as the rake surface 3 progresses in the insert thickness direction from the rake surface 3 toward the seating surface 2. Immerse in the direction. Therefore, the bottom portion of the sub-groove portion 7 is disposed at a position protruding in the insert width direction from the portion of the flank 4 that intersects the seating surface 2. Accordingly, the sub-groove portion 7 is formed in a portion near the rake face 3 excluding a portion near the seating surface 2 in the end portion in the width direction of the insert 1. Moreover, the insert width direction wall surface of the sub-groove part 7 is extended in parallel with an insert thickness direction.

  Here, the shape of the sub-groove portion 7 of the present invention will be described in detail by taking up each dimension.

  First, in the present embodiment, since the sub-groove portion 7 is formed with a smaller width than the main groove portion 6, the two groove portions 6 and 7 having different widths can be formed. By forming the width of the main groove portion 6 to be large, the ratio of the first divided main cutting edge to the entire insert is reduced, and the cutting resistance can be reduced, so that chatter vibration that occurs during cutting can be prevented. In addition, since the width of the sub-groove portion 7 is formed to be small, a large decrease in the cutting edge strength, and chipping, chipping, breakage, and the like of the cutting edge, which are seen in an insert in which a plurality of large main groove portions are formed, are suppressed. Is done. Therefore, the strength reduction of the first divided main cutting edge can be prevented while achieving the function of further subdividing the chips. Accordingly, the main cutting edge can be prevented from being lost, and the life of the insert 1 can be extended. As described above, by using the insert 1 of the present embodiment, it is possible to reduce the cutting resistance while suppressing a decrease in the cutting edge strength, and it can be suitably used for heavy cutting.

  Moreover, according to this Embodiment, the length of the subgroove part 7 is formed shorter than the thickness of a main-body part. The flank 4 formed between the two main grooves 6 is divided into a plurality of parts by the sub-grooves 7, and the divided flank 4 is continuous on the seating surface side. As a result, the flank portion sandwiched between the two main groove portions 6 or the flank portion sandwiched between the sub groove portion 7 and the main groove portion 6 is prevented from being lost, and the cutting edge strength can be improved. In addition, the strength of the insert body can be sufficiently secured. Further, since the other end of the sub-groove portion 7 is located on the flank 4, there is no portion where the sub-groove portion 7 is immersed on the insert seating surface 2. Thereby, while the intensity | strength of an insert main body is ensured as above-mentioned, since the insert seating surface 2 used as a restraint surface with respect to a holder becomes large, an insert can be restrained more stably to a holder.

  Furthermore, according to the present embodiment, the depth of the sub-groove portion 7 is formed smaller than the depth of the main groove portion 6. This prevents the rake face portion sandwiched between the two main groove portions 6 or the rake face portion sandwiched between the sub-groove portion 7 and the main groove portion 6 from being lost, and the cutting edge strength can be improved.

  In addition, according to the present embodiment, as described above, the cutting force can be reduced as much as possible by setting the critical groove at which the depth of the main groove portion 6 cannot be expected to decrease even when the depth of the main groove 6 is deeper than that. Can be made smaller. Further, the sub-groove portion 7 is set to be larger than the preset maximum feed amount per cutting edge of the rolling tool 12, so that the width of the chip can be reliably divided. Moreover, the fall of cutting-edge intensity | strength can be suppressed by setting the depth of the subgroove part 7 to the depth of the main groove part 6 or less.

  As described above, the sub-groove portion 7 according to the present invention has three dimensions of width W, depth D, and length L as the components of the groove portion as described below. As shown in FIG. 2 (a), the width W of each groove is a dimension in the insert longitudinal direction, and is an intersection ridgeline portion between the rake face 3 and the wall surface of each groove, and an imaginary straight line of the main cutting edge 5. Is the shortest distance between the two intersections. Moreover, the depth D of each groove part is a dimension of an insert width direction, and is the longest distance in the insert width direction in the top view from the virtual straight line of the main cutting edge 5 to the said crossed ridgeline part of each groove part. Further, as shown in FIG. 2 (b), the length L of each groove is a dimension in the thickness direction of the insert. Each length reaching the rake face 3 when the seating surface 2 of the insert 1 is left as a bottom surface. This is the shortest distance in the insert thickness direction from one end to the other end of the groove.

  Here, particularly in the width W2 of the sub-groove portion 7, it is preferable that the width is 1/6 to 5/6 of the width W1 of the main groove portion 6 in terms of achieving a good balance between reducing cutting resistance and maintaining cutting edge strength. . If the width W2 of the sub-groove portion 7 is smaller than 1/6 of the width W1 of the main groove portion 6, the effect of reducing cutting resistance is insufficient, and if it is larger than 5/6 of the width W1 of the main groove portion 6, the strength of the cutting edge portion. Is insufficient. That is, such a configuration can effectively maintain the cutting edge length of the second divided main cutting edge 5a, and is effective in preventing chipping, chipping, breakage, and the like of the cutting edge.

  In particular, the depth D2 of the sub-groove portion 7 is preferably 1/6 to 5/6 of the depth D1 of the main groove portion 6. If the depth D2 of the sub-groove portion 7 is smaller than 1/6 of the depth D1 of the main groove portion 6, the depth D2 of the sub-groove portion tends to be smaller than the feed amount during heavy cutting, so chips are divided. The cutting resistance is not sufficiently reduced. Further, when the chips are not divided, the chips come into contact with the groove wall surface of the sub-groove portion 7, so that the cutting resistance is likely to increase as a result. If the depth D2 of the sub-groove portion 7 is larger than 5/6 of the depth D1 of the main groove portion 6, the strength of the cutting edge portion becomes insufficient and the strength of the insert main body portion also decreases.

  Furthermore, in the present embodiment, the length L1 of the main groove 6 is substantially the same as the thickness of the insert 1, but the length L2 of the sub-groove 7 is formed shorter than the thickness of the insert 1. With such a configuration, the other end of the sub-groove portion 7 is positioned on the split flank 4A, so that the cutting edge strength is greater than when the number of the main groove portions 6 that reach the seating surface 2 is simply increased at the other end. And further, a decrease in the strength of the insert main body can be suppressed.

  Specifically, in the present embodiment, the width W1 of the main groove portion 6 is 1.6 mm, the depth D1 of the main groove portion 6 is 1.2 mm, and the length L1 of the main groove portion 6 is 6 mm. Set to 4 mm. The width W2 of the sub-groove portion 7 is 0.6 mm, the depth D2 of the sub-groove portion 7 is 0.4 mm, and the length L2 of the sub-groove portion 7 is set to 2.4 mm. Needless to say, these specific numerical values depend on the size of the insert body.

  In the present embodiment, the main groove portion 6 formed in the insert is formed in the same manner, and similarly, the sub-groove portion 7 formed in the insert is formed in the same shape. However, the present invention is not limited thereto. In the range which has the effect of the above-mentioned main groove part 6 and subgroove part 7, you may form so that subgroove part 7 may differ so that main groove part 6 may differ. However, in such a case, the values used to calculate the numerical relationship between the width and depth of the main groove portion 6 and the sub-groove portion 7 are the same as the width and depth of the main groove portion 6 of the main groove portion 6 formed in the insert. Of these, the maximum width and depth are the minimum width and depth of the sub-groove portion 7 formed in the insert. If these values are measured and the width and depth of the obtained sub-groove portion 7 are within 1/6 to 5/6 of the width and depth of the main groove portion 6, the above-described effects can be obtained.

  Each sub-groove portion 7 is formed to have at least one of depth, width and length smaller than that of the main groove portion 6. That is, even if the depth and width of each sub-groove portion 7 are small, only the depth or only the width may be smaller than that of the main groove portion 6. For example, the other end of the sub-groove portion 7 is illustrated as not reaching the seating surface 2, but the present invention is not limited to this, and the clearance angle of the flank 4, the thickness of the insert body portion, In the case where the strength of the insert body portion can be sufficiently maintained due to the balance with the width W2 and the depth D2, the same effect can be obtained even if the other end of the sub groove portion 7 is formed to reach the seating surface 2. Needless to say. Incidentally, as described above, in the present embodiment, each sub-groove portion 7 is formed smaller in depth, width, and length than each main groove portion 6.

  Next, an experiment conducted for examining the cutting performance of the insert of this embodiment will be described. 4A to 4D are plan views showing the cutting edge shapes of various inserts used in this experiment in a simplified manner. Specifically, the number of sub-grooves formed in the insert is a plan view of each of the insert 10 of this embodiment, which is different from the insert 1 of this embodiment, and the inserts 110A, 110B, and 110C of comparative examples. The insert 10 of this embodiment has three main groove parts 6 and four sub groove parts 7 as shown in FIG.4 (b). On the other hand, the insert 110A of the first comparative example has three main groove portions 6 as shown in FIG. The insert 110B of the second comparative example has seven main groove portions 6 as shown in FIG. Further, the insert 110C of the third comparative example has seven sub-grooves 7 as shown in FIG. In addition, in the insert 10 of this embodiment and the inserts 110A, 110B, and 110C of the first to third comparative examples, the sizes of the main groove 6 and the sub-groove 7 are formed to be the same.

  The insert 110 </ b> A of the first comparative example has a divided main cutting edge that is substantially divided into four by the three main groove portions 6. On the other hand, the insert 10 of the present embodiment is such that the auxiliary groove portion 7 is further formed in the insert 110A of the first comparative example, and the main cutting edge divided by the main groove portion 6 is further separated by the respective auxiliary groove portions 7 respectively. Divided into two. In addition, the insert 110B of the second comparative example has a divided main cutting edge that is divided into approximately eight equal parts by the seven main groove portions 6, and the insert 110C of the third comparative example is approximately divided into eight equal parts by the seven sub groove portions 7. It has a split main cutting edge.

In order to compare the cutting resistance of each insert, the cutting edge strength, and the state of the finished surface using these inserts, the cutting speed V is set to 200 m / min, and SS400 defined in JIS as a work material. A cutting test was carried out by a dry method. Further, the cutting amount in the holder axial direction was 15 mm, the cutting amount in the holder radial direction was 5 mm, and the feed amount f per insert blade was 0.2 mm / blade at the time of cutting resistance and finished surface measurement. The results are shown in Table 1. The cutting resistance was measured using a cutting resistance measuring device manufactured by Kistler under the above-described cutting conditions, and the main component force was expressed as the cutting resistance. For the cutting edge strength, the feed amount was increased so that the load applied to the insert gradually increased, and the test was conducted until the insert was finally lost, and the limit feed at which the insert was lost was indicated. Specifically, the feed amount per insert blade was increased, and the feed amount when the main cutting edge of the insert was lost was expressed.

  The cutting resistance increases in proportion to the contact surface between the insert and the work material, that is, the total length of each divided main cutting edge provided in the insert. Therefore, in principle, the more the grooves 6 and 7 formed in each insert, the lower the cutting resistance. Compared with the insert 110A of the first comparative example, the contact surface with the work material is reduced by the amount of the sub-groove 7 formed, so the cutting resistance of the insert 10 of this embodiment is higher than that of the insert 110A of the first comparative example. Also lower. Moreover, even if it increases only the subgroove part 7 like the insert 110C of a 3rd comparative example, the fall rate of cutting resistance is small compared with the case where the main groove part 6 is increased. This is because, first of all, the total length of each divided main cutting edge provided in the insert is long, that is, the contact surface with the work material is large. In addition, since the sub-groove portion 7 has a small depth D and width W, the uncut portion is likely to come into contact with the wall surface of the sub-groove portion 7, thereby resulting in a new increase in cutting resistance. It cannot be reduced. Further, in the case of the insert composed of the sub-groove part 7 as in the insert 110C of the third comparative example, since the sticky work material is not easily divided, the chips are not connected to each other in a reliable state. Chips are easily generated. For this reason, the effect of forming the groove cannot be obtained. On the other hand, the insert 10 according to the present embodiment reliably cuts chips with the main groove portion 6 even for a tough work material, and suppresses a decrease in cutting edge strength with the auxiliary groove portion 7. The cutting resistance can be reduced. In addition, when neither the main groove part 6 nor the sub-groove part 7 is formed, cutting resistance will be about 5000N.

  Further, the cutting edge strength increases in proportion to the length of the divided main cutting edge. In other words, the cutting edge strength decreases as each divided main cutting edge becomes shorter. Therefore, the cutting edge strength of the insert 110B of the second comparative example in which the main groove portion 6 is increased is lower than that of the insert 110A of the first comparative example. On the other hand, the insert 10 of this embodiment forms the sub-groove part 7 smaller than the main groove part 6, so that the cutting edge strength with respect to the insert 110A of the first comparative example is higher than the insert 110B of the second comparative example. Can be suppressed.

Further, when the depth D2 of the minor groove portion 7 is smaller than the holder cutting amount f per blade (f> D2), both the insert longitudinal direction wall surfaces and the insert width direction wall surfaces of the minor groove portion 7 are left uncut. The parts are easy to touch. In this case, the contact surface between the work material and the insert is further increased, the cutting resistance is increased accordingly, and the cutting edge is liable to be broken. This reduces the cutting edge strength. Therefore, the insert 10 of the present embodiment is formed such that the depth D2 of the sub-groove portion 7 is larger than the maximum value f _max of the expected feed amount per insert blade. As a result, an increase in cutting resistance due to the sub-groove portion 7 can be suppressed, a reduction in cutting edge strength can be prevented, and cutting resistance can be reduced. For example, in the insert 10 of this embodiment, the maximum value f _max of the expected feed amount is set to 0.3 mm / tooth.

  Further, the difference between the concave and convex portions generated on the finished surface of the work material after cutting is greatly affected by the cutting resistance. Since the insert 10 of the present embodiment has a lower cutting resistance than the insert 110A of the first comparative example as described above, the difference in unevenness of the finished surface is reduced compared to the insert 110A of the first comparative example, and the finished surface is Can be smooth.

  Thus, in order to enable heavy cutting with severer cutting conditions, when the number of main grooves 6 is increased as compared with the insert 110A of the first comparative example, the cutting resistance is reduced, but the cutting edge strength is reduced. Since it drops to half, it becomes difficult to use in heavy cutting. In addition, as described above, when only a plurality of sub-groove portions 7 are provided as in the insert 110C of the third comparative example, it is possible to suppress a reduction in cutting edge strength, but the cutting resistance does not sufficiently decrease. Finally, it becomes difficult to use in heavy cutting.

  On the other hand, like the insert 10 of this embodiment, the auxiliary groove part 7 smaller than the main groove part 6 is attached to the insert 110A of the first comparative example, that is, the main groove part 6 and the auxiliary groove part 7 coexist. Accordingly, it is possible to suppress a reduction in cutting edge strength while reducing cutting resistance. As a result, it is possible to perform heavy cutting with severe cutting conditions using the insert 10 of the present embodiment.

  Next, the arrangement position of the sub groove portion 7 in the insert will be described.

  As shown in FIGS. 1 and 2, in the present embodiment, the sub-groove portion 7 is arranged so as to divide the first divided main cutting edge 5A substantially equally, and forms the second divided main cutting edge 5a. Thereby, since the cutting resistance concerning each 2nd division | segmentation main cutting edge 5a is disperse | distributed equally, cutting resistance is reduced and the fall of cutting edge strength can be suppressed to the maximum. Further, since the lengths of the second divided cutting edges can be obtained equally, chipping of the cutting edges can be suppressed.

  In the present embodiment, the main cutting edge 5 has a first divided main cutting edge 5A having a long insert longitudinal dimension and a first divided main cutting edge 5A having a short insert longitudinal dimension. The long first divided main cutting edge 5 </ b> A is divided into three second divided main cutting edges 5 </ b> A by two sub-groove portions 7. The short first divided main cutting edge 5A is divided into two divided main cutting edges 5A by one sub-groove portion 7. Accordingly, the second divided main cutting edge 5A can be shortened regardless of the length of the first divided main cutting edge 5A. Thus, each sub-groove part 7 is arrange | positioned in the position which divides the 1st division | segmentation main cutting edge 5A into 2 or 3 equal parts. Here, in the present embodiment, the case where the first divided main cutting edge 5A is divided into two equal parts and three equal parts by the sub-groove part 7 is illustrated, but the present invention is not limited to this and is divided into two equal parts. Needless to say, the same effect can be obtained by dividing into three equal parts, four equal parts, etc.

  Furthermore, in FIG. 1 and FIG. 2, the insert 1 formed by dividing the main cutting edge 5 by the three main groove portions 6 is illustrated, but as the second embodiment of the present invention, the main cutting edge 5 is divided into four main groove portions. The insert 21 divided by 6 is shown in FIG. Cutting using an insert having a main groove 6 in the main cutting edge 5 as in the embodiment shown in FIGS. 1, 2, and 5, that is, cutting using a rolling tool 11 as shown in FIG. 3. In the processing, uncut parts are inevitably left on the wall surface of the work material after the processing. Therefore, in order not to cause uncut portions due to the groove portion, inserts 1X and 1Y having different main groove portions 6 are disposed on the same circumference of the holder 12 as shown in FIG. Thereby, the cutting edge of the other insert 1Y can be machined away from the uncut portion by the groove portion of one insert 1X. For example, the insert 1 of the first embodiment can be used as the insert 1X, and the insert 21 of the second embodiment can be used as the insert 1Y. At that time, there are a portion cut by the divided main cutting edge of one insert and a portion cut by the divided main cutting edge of both inserts on the processing wall surface of the work material. At this time, the central portion of the generated chip cross-section corresponds to a portion cut only by the divided main cutting edge of one insert, and is therefore the thickest. Therefore, it is preferable that the protrusion described later is arranged so that the protrusion comes into contact with the central portion of the chip. As a result, the protrusion comes into contact with the portion where the cross section of the chip is thickest, so that the chip is curled efficiently and stably.

  Moreover, the insert 31 of 3rd embodiment from which the number of the subgroove parts 7 differs with respect to the insert 1 of 1st embodiment was shown in FIG. In the present embodiment, three main groove portions 6 and two sub groove portions 7 are formed. In the inserts 1 and 21 shown in FIG. 1, FIG. 2, and FIG. 5, the secondary groove portion 7 is provided between two main groove portions adjacent to each other in the insert longitudinal direction, and between the main groove portion 6 and the insert longitudinal end surface portion. Was formed. On the other hand, in the third embodiment shown in FIG. 6, the sub groove portion 7 is an insert formed only between the main groove portion 6 and the insert longitudinal direction end surface portion. That is, in this embodiment, the sub-groove part 7 is formed in the longer first divided main cutting edge located on the insert longitudinal direction end face side. Since the first divided main cutting edge positioned on both end surfaces in the insert longitudinal direction is continuously arranged at the corners of the insert, chipping is likely to occur. Therefore, the first divided main cutting edge located on both end faces in the longitudinal direction of the insert needs to have sufficient cutting edge strength at the time of cutting, particularly at the time of heavy cutting. In such a case where the main groove 6 is formed on the first divided main cutting edge located on both side surfaces in the longitudinal direction of the insert, it is difficult to use for heavy cutting with severe cutting conditions. In the present embodiment in which the groove portion 7 is formed, cutting resistance can be effectively reduced while maintaining the cutting edge strength. These are particularly important when the dimensions of the insert body are small. As a result, chipping is suppressed, and a long-life insert can be realized even in heavy cutting.

  In FIG. 7, in addition to the components of the inserts of the first to third embodiments described above, the first divided main cutting edge 5A is provided on the rake face 3 adjacent to the first divided main cutting edge 5A. Correspondingly, at least one protrusion 8 is formed. Specifically, an insert 41 according to a fourth embodiment in which a protrusion 8 is formed so as to be paired with the first divided main cutting edge 5A is shown. The main cutting edge side of the protrusion 8 has a branched shape so as to correspond to the second divided main cutting edge 5 a further divided by the sub-groove portion 7. With such a configuration, the protruding portion of the protrusion 8 hits the thickest portion of the above-described chip cross section, and the generated chip can be curled selectively and efficiently. As a result, it is possible to prevent chips from damaging the holder wall surface in the chip pocket. Further, each chip formed in a narrow width comes into contact with a protrusion formed on the rake face, whereby the radius of curvature is reduced and the size of the chip is reduced. As a result, the chips smoothly move from the chip pocket to the outside of the holder, and the chip discharge performance can be improved. As a result, defects such as chip clogging and chip biting in the chip pocket are suppressed, and the throwaway insert and the holder can be used for a long period of time.

  The protrusion 8 forms a pair with the first divided main cutting edge 5A, and does not take a shape in which the main cutting edge side is branched so as to correspond to the second divided main cutting edge 5a. As in the form of the insert 51, the protrusion 8 may be independent for each of the second divided main cutting edges 5a. That is, it is important that the protrusion 8 is disposed so as to correspond to the second divided main cutting edge 5A. Here, the phrase “disposed so as to correspond to the second divided main cutting edge 5A” means that the chips generated by the corresponding second divided main cutting edges 5a hit the raised portions and are curled. By doing so, the same effect can be obtained regardless of the shape of the rake face center side of the protrusion 8.

  Furthermore, an annular raised portion 14 is formed around the screw hole 15 at the center of the rake face 3 as shown in FIG. This ensures that the chips are curled. As a result, the chips hit the holder wall surface in the chip pocket 13 and are discharged to the outside without damaging the holder wall surface. Therefore, the holder 12 can have a long life, and further, since the chipping of the main cutting edge 5 due to chipping is suppressed, the insert can also have a long life.

  As shown in FIG. 9, when the insert is mounted on the holder 12, the head of the clamp screw 16 is hidden by the annular ridge 14, that is, the head of the clamp screw 16 is lower than the annular ridge 14. Therefore, it is possible to prevent wear of the head of the clamp screw 16 due to the collision of chips.

  1 to 9 exemplify inserts in which the main body portion has a substantially parallelogram plate shape, but as another embodiment of the present invention, the main body portion has a substantially polygonal plate corresponding to the holder shape. Needless to say, the same effect can be obtained even when formed in a substantially disk shape.

  As mentioned above, although embodiment of this invention was illustrated, this invention is not limited to embodiment, It cannot be overemphasized that it can be made arbitrary, unless it deviates from the objective of invention.

1 is an overall perspective view of a throw-away insert according to a first embodiment of the present invention. It is (a) top view of the throw away insert of FIG. 1, (b) Long side side view, (c) Short side side view. It is a whole perspective view of the turning tool using the throw away insert of the present invention. It is a simplification figure of the cutting edge shape of various inserts used for the evaluation experiment of cutting performance of this embodiment. It is (a) top view of the throw away insert by 2nd embodiment, (b) Long side side view, (c) Short side side view. It is a whole perspective view of the throw away insert by 3rd embodiment. It is a whole perspective view of the throw away insert by a 4th embodiment. It is the whole throwaway insert perspective view by a 5th embodiment. It is an expansion perspective view which shows the throw away insert mounting state of the cutting tool of this invention.

Explanation of symbols

1 Throw away insert (insert)
1X, 1Y Insert with different arrangement of main groove 6 2 Seating surface 3 Rake face 4 Relief face 4A Divided relief face 5 Main cutting edge 5A First divided main cutting edge 5a Second divided main cutting edge 6 Main groove 7 Sub groove 8 Protrusion 10 Inserts 110A, 110B, and 110C of the first to third comparative examples with different numbers of sub-grooves 11 Inserts of the first to third comparative examples 11 Turning tools 12 Holders 13 Chip pockets 14 Annular raised portions 15 Screw holes 16 Clamp screws 21 Second Insert according to the embodiment 31 Insert according to the third embodiment 41 Insert according to the fourth embodiment 51 Insert according to the fifth embodiment

Claims (10)

A rake face formed on the upper surface of the substantially plate-shaped body,
A seating surface formed on the lower surface of the main body,
A flank formed on the side surface of the main body,
A main cutting edge formed at an intersection ridge line portion between the rake face and the flank face;
A main groove formed on the flank and having both ends reaching the rake surface and the seating surface;
A throw-away insert with
The main cutting edge and the flank are each composed of a plurality of first divided main cutting edges and a divided flank divided by the main groove, and the first divided main cutting edge has one end on the rake face. A throw-away insert comprising a plurality of second divided main cutting edges which are arranged on the divided flank side by side so as to reach the main groove and are divided by sub-grooves having a width smaller than the width of the main groove. The throwaway insert according to claim 1, wherein a length of the sub-groove portion is shorter than a thickness of the main body portion. The throwaway insert according to claim 1 or 2, wherein a depth of the sub-groove portion is smaller than a depth of the main groove portion. The throwaway insert according to any one of claims 1 to 3, wherein the depth of the main groove portion and the sub groove portion is larger than a preset maximum feed amount per blade of the rolling tool. The throwaway insert according to any one of claims 1 to 4, wherein a width of the sub-groove portion is 1/6 to 5/6 of a width of the main groove portion. The throwaway insert according to any one of claims 1 to 5, wherein the sub-groove portion is disposed so as to substantially divide the first divided main cutting edge. The throwaway insert according to any one of claims 1 to 6, wherein at least one protrusion is disposed on the rake face corresponding to the second divided main cutting edge. The throwaway insert according to any one of claims 1 to 7, further comprising a screw hole penetrating to the seating surface in the center of the rake face and an annular raised portion around the screw hole. . A turning tool comprising: the throwaway insert according to any one of claims 1 to 8; and a tip holder on which a plurality of the throwaway inserts are mounted. The rolling tool according to claim 9, wherein the main groove portion and the sub groove portion are formed along a circumferential direction around an axis of the chip holder.

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