Cutting inserts

Abstract

Provided is a cutting insert capable of suppressing the softening of the bonding material in the bonding surface between a sintered body and a substrate, improving the bonding strength, and realizing the miniaturization of the sintered body. The cutting insert 10 includes a sintered body 20 having a cutting edge and a substrate 21, and the sintered body 20 is bonded to the front end of the substrate 21 by a brazing material A. The sintered body 20 has a front side 40 facing the front end side, an upper side 42 connected to the front side 40, a bottom side 43 opposite to the upper side 42, a back side 44 opposite to the front side 40, and two side sides 45 and 46. A cutting edge 50 is formed on a connecting ridge 41 between the upper side 42 and the front side 40. The sintered body 20 and the substrate 21 are bonded at a bonding surface 70 including the bottom side 43 and the back side 44 of the sintered body 20. Viewed from the side, the bonding surface 70 is stepped with the front side being low and the rear side being high.

Description

Technical Field

[0001] The present invention relates to a cutting insert. Background Art

[0002] The cutting insert for machining high hardness materials, for example, grooving, is formed by joining a sintered body such as a CBN sintered body as a cutting edge to a base insert (matrix) through a brazing material. In such brazing, usually two surfaces (bottom and back) of a roughly rectangular parallelepiped sintered body are brazed to the matrix (see Patent Document 1).

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Publication No. 2011-167805

[0006] Technical issues

[0007] However, in the brazing method, when processing is performed under high load conditions such as high speed, high feed, large cutting depth, and dry processing, the high temperature heat of the cutting edge of the sintered body is transferred to the brazing material, which may soften the brazing material. At this time, the sintered body may fall off from the base body and the sintered body may be damaged.

[0008] Furthermore, in the above-mentioned cutting insert, when machining is performed under high load conditions, a large load is applied to the brazed portion, which may cause damage to the sintered body. Therefore, it is desired to improve the brazing strength.

[0009] In addition, in the above-mentioned cutting inserts, since the price of the sintered body is high, the more the amount of the sintered body material used, the more expensive the cutting insert becomes. Therefore, miniaturization of the sintered body is desired.

[0010] The present invention has been made in view of this point, and an object of the present invention is to provide a cutting insert capable of suppressing softening of a bonding material such as a brazing filler metal at a bonding surface between a sintered body and a base body, improving bonding strength, and achieving miniaturization of the sintered body. Summary of the invention

[0011] A cutting blade according to one aspect of the present invention comprises a sintered body having a cutting edge and a substrate, wherein the sintered body is joined to the front end of the substrate by a joining material, the sintered body having a front face facing the front end side, an upper face connected to the front face, a bottom face opposite to the upper face, a back face opposite to the front face, and two side faces connected to the front face, the upper face, the bottom face and the back face, a cutting edge being formed on a connecting ridge between the upper face and the front face, the sintered body and the substrate being joined at a joining surface including the bottom face and the back face of the sintered body, and the joining surface is stepped in a manner that is low on the front end side and high on the back end side when viewed from the side.

[0012] According to the above aspect, since the joint surface between the sintered body and the substrate is stepped, the front end side of the joint surface that becomes hotter due to cutting by the cutting edge (joining material on the front side of the sintered body) will be away from the cutting edge. Therefore, it is possible to suppress the softening of the joining material on the joint surface due to heat. In addition, since the joint area of ​​the joint surface between the sintered body and the substrate becomes larger, the joint strength can be improved. In addition, since the rear side of the joint surface is close to the top of the sintered body, the sintered body on the back side becomes thinner, so the sintered body is correspondingly miniaturized.

[0013] In the above aspect, the joining surface has a plurality of joining planes extending from the front end side to the rear and a plurality of joining vertical surfaces extending upward, and the joining planes and the joining vertical surfaces may be alternately arranged from the front end side toward the rear.

[0014] In the above aspect, the joining plane may be inclined, viewed from the side, with the rear side being lower than the front side.

[0015] In the above aspect, a first joint plane on the front end side and a second joint plane behind the plurality of joint planes may have the same length in the front-rear direction, or the first joint plane may have a longer length than the second joint plane.

[0016] In the above aspect, a rear second joint plane among the plurality of joint planes may have a longer length than a front end side first joint plane.

[0017] In the above aspect, the joint surface has a joint intermediate surface connecting the joint plane and the joint vertical surface, and the joint intermediate surface can be curved to be convex when viewed from the side.

[0018] In the above aspect, the height of the front surface of the sintered body, as viewed from the side, may be 110% or more of the height of the rear surface.

[0019] In the above aspect, the engagement surface may also have a protruding shape protruding downward behind the stepped shape when viewed from the side. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is a perspective view showing an example of the cutting tool according to the present embodiment.

[0021] Figure 2 It is a perspective view of the cutting insert according to the present embodiment.

[0022] Figure 3 This is an enlarged view of the front end of the cutting insert.

[0023] Figure 4 is a side view of the front end of the cutting insert.

[0024] Figure 5 It is a top view of the front end of the cutting insert.

[0025] Figure 6 It is a front view of the front end of the cutting insert.

[0026] Figure 7 It is a three-dimensional diagram of a sintered body.

[0027] Figure 8 It is a stereoscopic view of the front end of the substrate.

[0028] Fig. 9 This is a side view of the front end portion of the cutting insert when the second joint plane is longer than the first joint plane.

[0029] Fig.10 is a side view of the front end portion of the cutting insert when the engagement surface has a protruding shape that bulges downward.

[0030] Fig.11 This is a plan view of the front end portion of the cutting insert when the rear end surface of the engagement surface is formed in a wavy shape.

[0031] Main component symbols

[0032] Cutting tools 1

[0033] Cutting blade 10

[0034] Sintered body 20

[0035] Base 21

[0036] Front 40

[0037] Top 42

[0038] Bottom 43

[0039] Back 44

[0040] Side 45, 46

[0041] Cutting edge 50

[0042] Joint surface 70

[0043] Brazing material A DETAILED DESCRIPTION

[0044] Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings.

[0045] Figure 11 is a perspective view showing an example of a cutting tool 1 having a cutting insert 10 according to the present embodiment. The cutting tool 1 is, for example, a tool for grooving. The cutting tool 1 includes a cutting insert 10 and a tool body 11 for holding and fixing the cutting insert 10. The cutting tool 1 can be fixed to the tool body 11 by screwing a screw 12.

[0046] The tool body 11 has an elongated shape and holds the cutting insert 10 at its front end. The structure and shape of the tool body 11 are not limited thereto.

[0047] Figure 2 is a perspective view of a cutting insert 10 according to this embodiment. Figure 3 It is an enlarged view of the front end portion of the cutting insert 10 . Figure 4 1 is a side view of the front end of the cutting blade 10. Figure 5 is a top view of the front end of the cutting insert 10, Figure 6 1 is a front view of the front end of the cutting insert 10. In addition, in this specification, the side where the cutting edge of the cutting insert 10 is located in the longitudinal direction is defined as the "front end side", and the opposite side is defined as the "rear side". In addition, the longitudinal direction of the cutting insert 10 is defined as the "front-rear direction X", the direction that is perpendicular to the front-rear direction X and parallel to the upper surface 42 of the cutting insert 10 described later is defined as the "left-right direction Y", and the direction perpendicular to the upper surface 42 of the cutting insert 10 is defined as the "up-down direction Z".

[0048] like Figure 2 As shown, the cutting insert 10 has an elongated rectangular parallelepiped shape as a whole. The cutting insert 10 includes a sintered body 20 having a cutting edge and a base body 21 joined to the sintered body 20. The sintered body 20 is joined to the base body 21 via a brazing material A as a joining material.

[0049] The base body 21 has an elongated shape that is long in the front-rear direction X, and the sintered body 20 is joined to a front end portion 21 a thereof.

[0050] The sintered body 20 is, for example, a CBN (cubic boron nitride) sintered body, a diamond sintered body, or the like. Figure 3 As shown, the sintered body 20 is in a substantially hexahedral three-dimensional shape, and has a step at its bottom. The sintered body 20 has, for example, a front face 40 facing the front end side, an upper face 42 connected to the front face 40, a bottom face 43 opposite to the upper face 42, a back face 44 opposite to the front face 40, two side faces 45 and 46 connected to and opposite to the front face 40, the upper face 42, the bottom face 43, and the back face 44, and a connecting ridge 41 is formed between the upper face 42 and the front face 40.

[0051] exist Figure 6 In the front view shown, the front face 40 has a generally rectangular shape. Figure 4 In the side view shown, in the up-down direction Z, the front surface 40 is inclined, and gradually recedes as it approaches the bottom surface 43 (goes downward) from the top surface 42.

[0052] exist Figure 5 In the top view shown, the upper surface 42 has a substantially rectangular shape. A straight connecting ridge 41 is formed between the upper surface 42 and the front surface 40, and the connecting ridge 41 is a cutting edge 50. The cutting edge 50 is slightly curved, and the two ends of the cutting edge 50 are retreated to the rear side when viewed from above. In addition, the upper surface 42 is a rake face. The width of the upper surface 42 in the left-right direction Y gradually narrows from the front end to the rear.

[0053] like Figure 3 As shown, a connecting ridge 60 is formed between the side surfaces 45, 46 and the upper surface 42, and the connecting ridge 60 is also a transverse cutting edge 61. Figure 6 In the front view shown, in the up-down direction Z, the side surfaces 45 and 46 are inclined, and gradually approach the center in the left-right direction Y as they approach the bottom surface 43 from the top surface 42 (go downward).

[0054] like Figure 4 As shown, the sintered body 20 is joined to the base body 21 at the bottom surface 43 and the back surface 44 , and these portions form the joining surface 70 .

[0055] exist Figure 4 In the side view shown, the bottom surface 43 and the back surface 44 are stepped with the front side being low and the rear side being high. Figure 4 and Figure 7 As shown, the bottom surface 43 has a first plane 80, a first vertical surface 81, an intermediate surface 82, and a second plane 83 in order from the front end side to the rear side. The first plane 80 and the first vertical surface 81, the first vertical surface 81 and the intermediate surface 82, and the intermediate surface 82 and the second plane 83 are respectively connected to each other. The second plane 83 of the bottom surface 43 is connected to the back surface 44.

[0056] like Figure 7 As shown, the first plane 80, the first vertical surface 81 and the second plane 83 all have a long rectangular shape in the left-right direction Y. Figure 4 As shown, the first plane 80 and the second plane 83 are inclined, and the rear side is lower than the front side. That is, the first plane 80 and the second plane 83 have an angle relative to the upper surface 42. The middle surface 82 is curved to be concave in an arc shape toward the upper surface 42. In the vertical direction Z, the first vertical surface 81 is slightly inclined, and approaches the back surface 44 side as it approaches the upper side.

[0057] like Figure 7 As shown, the back surface 44 has a long rectangular shape in the left-right direction Y. Figure 4Although it is difficult to find in the figure, the back surface 44 is slightly inclined in the up-down direction Z, and approaches the front surface 40 side as it approaches the bottom. In addition, the back surface 44 may also be a surface perpendicular to the top surface 42.

[0058] like Figure 8 As shown, the front end 21a of the base 21 has an upper surface 21b on which the sintered body 20 is placed and bonded. The upper surface 21b has a stepped shape corresponding to the stepped shape of the bottom surface 43 and the back surface 44 of the sintered body 20, with the front end side being low and the rear side being high.

[0059] The upper surface 21b of the base 21 has, in order from the front end side toward the rear side, a first plane 90, a first vertical surface 91, an intermediate surface 92, a second plane 93, and a second vertical surface 94. The first plane 90 and the first vertical surface 91, the first vertical surface 91 and the intermediate surface 92, the intermediate surface 92 and the second plane 93, and the second plane 93 and the second vertical surface 94 are connected to each other.

[0060] The first plane 90, the first vertical surface 91, the second plane 93 and the second vertical surface 94 are all in the shape of a long rectangle in the left-right direction Y. The first plane 90 and the second plane 93 are inclined, and the rear side is lower than the front side. The middle surface 92 is curved in an upward convex arc shape. In the up-down direction Z, the first vertical surface 91 and the second vertical surface 94 are slightly inclined and recede as they approach the top.

[0061] The joint surface 70 between the sintered body 20 and the base body 21 is Figure 7 and Figure 8 The first plane 80 of the sintered body 20 and the first plane 90 of the substrate 21, the first vertical surface 81 of the sintered body 20 and the first vertical surface 91 of the substrate 21, the middle surface 82 of the sintered body 20 and the middle surface 92 of the substrate 21, the second plane 83 of the sintered body 20 and the second plane 93 of the substrate 21, and the back side 44 of the sintered body 20 and the second vertical surface 94 of the substrate 21 are bonded to each other through the solder A.

[0062] That is, the joint surface 70 has a stepped shape with the front end side being low and the rear side being high. Figure 4 In the side view shown, there is a first joint plane 100 extending from the front end side to the rear, a first joint vertical surface 101 connected to the first joint plane 100 and extending upward, a joint intermediate surface 102 connected to the first joint vertical surface 101, a second joint plane 103 connected to the joint intermediate surface 102 and extending from the front end side to the rear, and a second joint vertical surface 104 connected to the second joint plane 103 and extending upward. In addition, in this specification, "step-shaped" refers to a shape having two or more steps (joint planes).

[0063] For example, in the front-rear direction X, the first joint plane 100 and the second joint plane 103 have the same length, or the first joint plane 100 has a longer length than the second joint plane 103 .

[0064] The joint intermediate surface 102 is curved in an upwardly convex arc shape. In the up-down direction Z, the first joint vertical surface 101 and the second joint vertical surface 104 are slightly inclined, and approach the rear as they approach the top.

[0065] The height H1 of the front surface 40 of the sintered body 20 is 110% or more of the height H2 of the rear surface, preferably 120% or more and 400% or less, and more preferably 150% or more and 300% or less.

[0066] According to the present embodiment, since the joint surface 70 between the sintered body 20 and the substrate 21 is stepped, the front end side of the joint surface 70 (the brazing material A on the front side 40 of the sintered body 20) which becomes hotter due to the cutting of the cutting edge 50 will be away from the cutting edge 50. Therefore, it is possible to suppress the solder A on the joint surface 70 from softening due to heat. In particular, during the cutting and grooving process, the front cutting edge 50 is the place where the processing temperature is the highest. Since the front end side of the joint surface 70 is away from the cutting edge 50, it is possible to effectively suppress the softening of the solder A on the joint surface 70. In addition, since the joint area of ​​the joint surface 70 between the sintered body 20 and the substrate 21 becomes larger, the brazing strength can be improved. Therefore, it is possible to suppress the sintered body 20 from being peeled off from the substrate 21 and damaged. In addition, since the rear side of the joint surface 70 is close to the upper surface 42 of the sintered body 20, the sintered body 20 on the back side 44 becomes thinner, and the material consumption of the sintered body 20 is reduced accordingly, so that the sintered body 20 can be miniaturized. Therefore, the cost of the cutting insert 10 can be reduced.

[0067] In addition, for example, in a non-stepped joint, the brazing area of ​​the joint plane is mainly effective, and the joint vertical surface has only an auxiliary effect. However, if there is a step shape, a part of the joint vertical surface will be effective as a brazing area like the joint plane. In other words, the sintered body 20 that can convert a part of the area in the front-to-back direction X into the up-down direction Z can greatly reduce the size of the front-to-back direction X and reduce the volume, relative to the volume of the sintered body in which the stepped joint surface is pulled into a straight line with a thickness H1.

[0068] Since the first joint plane 100 and the second joint plane 103 of the joint surface 70 are inclined, the rear side is lower than the front side, so the joint area of ​​the joint surface 70 of the sintered body 20 and the substrate 21 becomes larger, and the brazing strength can be improved. In addition, since the sintered body 20 and the substrate 21 are easily engaged, the brazing strength can also be improved in this regard.

[0069] In the front-to-back direction X, the first joint plane 100 on the front end side and the second joint plane 103 on the rear end have the same length, or the first joint plane 100 has a longer length than the second joint plane 103. Therefore, the joint area of ​​the first joint plane 100 on the front end side that receives a large load during cutting becomes larger, and the brazing strength can be improved.

[0070] Since the joint intermediate surface 102 is curved and convex when viewed from the side, the joint area of ​​the joint surface 70 of the sintered body 20 and the base body 21 becomes larger, and the brazing strength can be improved.

[0071] The height H1 of the front surface 40 of the sintered body 20 is more than 110% of the height H2 of the back surface 44. Therefore, the rear side of the bonding surface 70 is very close to the upper surface 42 of the sintered body 20, making that part of the sintered body 20 very thin, and the sintered body 20 can be further miniaturized.

[0072] In the above embodiment, the first joint plane 100 at the front end is longer than the second joint plane 103 at the rear end. Fig. 9 As shown, the second bonding plane 103 at the rear may be longer than the first bonding plane 100 at the front end. In this case, the bonding area of ​​the bonding surface 70 between the sintered body 20 and the substrate 21 can be increased, and as a result, the brazing strength can be improved. Furthermore, in this case, the second bonding plane 103 may be longer than the first bonding plane 100 by more than 1.5 times.

[0073] In addition, if Fig.10 As shown, when viewed from the side, the joint surface 70 may also have a protrusion shape protruding downward behind the step shape. In this case, the joint surface 70 may have a stepped portion 150 composed of a first joint plane 100, a first joint vertical surface 101, a joint intermediate surface 102, and a second joint plane 103, and a protrusion 151 composed of a second joint vertical surface 160, a third joint plane 161, and a third joint vertical surface 162 behind it. Such an example can further increase the joint area of ​​the joint surface 70 between the sintered body 20 and the substrate 21, and as a result, the brazing strength can be improved. In addition, since the sintered body 20 and the substrate 21 are meshed with each other, the brazing strength can also be improved at this point.

[0074] like Fig.11 As shown, the second joint vertical surface 104, which is the rear end surface of the joint surface 70, can be formed into a wavy shape when viewed from above. In this case, for example, the back surface 44 of the sintered body 20 and the second vertical surface 94 of the substrate 21 are wavy. Such an example can further increase the joint area of ​​the joint surface 70 of the sintered body 20 and the substrate 21. As a result, the brazing strength can be improved.

[0075] The preferred embodiments of the present invention are described above with reference to the accompanying drawings, but the present invention is not limited to these examples. Obviously, those skilled in the art can think of various changes or modifications within the scope of the concept described in the claims, and it should be understood that these naturally also belong to the technical scope of the present invention.

[0076] In the above embodiment, the joint surface 70 may also be in other shapes, as long as the joint surface 70 has a stepped shape in the side view. The first joint plane 100 and the second joint plane 103 may not be inclined, that is, they are horizontal relative to the upper surface 42. The first joint vertical surface 101 and the second joint vertical surface 104 may be perpendicular to the upper surface 42. The joint intermediate surface 102 does not need to be bent into an arc shape. In addition, the joint intermediate surface 102 may not be provided, and the first joint vertical surface 101 and the second joint plane 103 may be directly connected.

[0077] The number of steps of the bonding surface 70 (the number of bonding planes) is not limited to 2 as in the above embodiment, but may be 3 or more. The shapes of the sintered body 20 and the base 21 are not limited to those in the above embodiment.

[0078] The cutting insert 10 described in the above embodiment is not limited to grooving processing, and can also be used for outer diameter processing, end surface processing, profiling processing, inner diameter processing, etc.

[0079] Industrial Applicability

[0080] The invention is used to provide a cutting insert and a cutting tool, the cutting insert having high chip controllability for both grooving and infeed processing.

Claims

1. A cutting insert, comprising: a sintered body having a cutting edge and a base body, the sintered body being joined to a front end of the base body by a joining material, The sintered body has a front surface facing the front end side, an upper surface connected to the front surface, a bottom surface opposite to the upper surface, a back surface opposite to the front surface, and two side surfaces connected to the front surface, the upper surface, the bottom surface and the back surface, and a cutting edge is formed on a connecting ridgeline between the upper surface and the front surface. The sintered body and the base are joined at a joining surface including a bottom surface and a back surface of the sintered body, When viewed from the side, the joint surface is in a stepped shape with a lower front end side and a higher rear end side; The joint surface has a plurality of joint planes extending from the front end side to the rear and a plurality of joint vertical surfaces extending upward. From the front end side toward the rear, the joint planes and the joint elevations are alternately arranged; Wherein, viewed from the side, the joining plane is inclined, with the rear side being lower than the front side.

2. The cutting insert according to claim 1, wherein A first joint plane on the front end side and a second joint plane behind the first joint plane of the plurality of joint planes have the same length in the front-rear direction, or the first joint plane has a longer length than the second joint plane.

3. The cutting insert according to claim 1, wherein A rear second joint plane among the plurality of joint planes has a length longer than a front end side first joint plane.

4. The cutting insert according to claim 1, wherein The joint surface has a joint intermediate surface connecting the joint plane and the joint vertical surface, Seen from the side, the joint middle surface is curved and convex.

5. The cutting insert according to claim 1, wherein When viewed from the side, the height of the front surface of the sintered body is 110% or more of the height of the rear surface.

6. The cutting insert according to claim 1, wherein The joint surface also has a protruding shape protruding downward behind the stepped portion when viewed from the side.

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