JP6164389B1 - Replaceable cutting tool - Google Patents

Abstract

In this cutting edge replaceable cutting tool, a cutting insert is seated on an insert mounting seat and is detachably mounted by being clamped by a clamp screw. A male screw portion is formed at one end portion of the clamp screw, and the other end portion. A head having a conical outer peripheral surface is formed, and a first cylindrical part is formed on the male screw part side between the male screw part and the head, and a first cylinder part is formed on the head side. Two cylindrical portions are formed, and a first flexible portion is formed between the first and second cylindrical portions.

Description

The present invention allows a cutting insert having an insert body formed with a cutting blade to be seated on a slit-like insert mounting seat formed at the tip of a tool body, and is detachable by being clamped by a clamp screw. The present invention relates to a cutting edge exchangeable cutting tool to be attached.
This application claims priority on September 24, 2015 based on Japanese Patent Application No. 2015-186854 for which it applied to Japan, and uses the content for it here.

  As such a blade-tip-exchange-type cutting tool, for example, Patent Document 1 discloses a blade-tip-exchange-type cutting in which a cutting insert is sandwiched between hollow insert mounting seats provided in a slit shape at the tip of a tool body and fixed with a fastening member. In the tool, the insert mounting seat side surface portion of the tool body is provided with a cone receiving surface that is eccentric in the direction of the rear end of the tool body with respect to the center line of the fastening member at a portion corresponding to the head cone surface of the fastening member. On the side surface portion of the insert mounting seat, a cylindrical portion receiving hole of the tightening member and its side wall and a female thread portion corresponding to the male thread portion of the tightening member connected to the side wall are provided, and the cutting insert is fixed by pressing by the side surface portion of the insert mounting seat, It is performed by pressing from the pin hole side surface of the cutting insert to the rear end side of the tool body by the cylindrical portion of the clamping member, and tightening the side wall of the cylindrical portion receiving hole. Only those which are brought into contact with the cylindrical portion of the member and the mounting reference surface is proposed.

  Here, in the blade-tip-exchange-type cutting tool described in Patent Document 1, as described above, the portion corresponding to the tightening member head conical surface of the insert mounting seat side surface portion of the tool main body is located with respect to the center line of the tightening member. By providing a conical receiving surface that is eccentric in the direction of the rear end of the tool body, by screwing the tightening member, the tightening member is deflected so that the head side of the tightening member is inclined toward the rear end side of the tool body, and the cylindrical portion of the tightening member By this, the pin hole side surface of the cutting insert is pressed to the tool body rear end side.

  Since the side wall of the cylindrical portion receiving hole and the cylindrical portion of the tightening member are brought into contact with each other as the mounting reference surface, the space between the lower end of the cylindrical portion and the front end side wall of the cylindrical portion receiving hole when the tightening member is bent in this way. The pressing force of the cutting insert by the cylindrical portion can be stabilized by pressing, and the mounting accuracy of the cutting insert can be kept high even with respect to loads in various directions and sizes during use of the tool.

Japanese Patent No. 3971522

  However, in the clamping member of the cutting edge exchangeable cutting tool described in Patent Document 1, the rigidity of the clamping member is high because the cylindrical portion is formed over the entire length between the male screw portion and the head. There is a problem that the fastening member is difficult to bend. In addition, since the cylindrical portion is formed over the entire length between the male screw portion and the head, the contact area between the cylindrical portion and the pin hole side surface of the cutting insert is increased, and the cylindrical portion has a pin hole side surface. The frictional resistance when pressing toward the rear end side of the tool body also increases, and the cutting insert may be displaced when the fastening member is tightened.

  The present invention has been made under such a background. While stabilizing the pressing force of the cutting insert as described above, the clamping member (clamp screw) can be easily bent, and cutting can be performed at the time of tightening. An object of the present invention is to provide a cutting edge-exchangeable cutting tool capable of preventing a situation in which an insert is displaced.

  In order to solve the above-described problems and achieve such an object, the present invention provides a cutting insert having an insert body in which a cutting blade is formed on a slit-like insert mounting seat formed at a tip portion of a tool body. Is a cutting edge exchangeable cutting tool that is detachably attached by being clamped by a clamp screw, and the insert body includes a seating surface that can contact the bottom surface of the insert seat. A through hole through which the clamp screw is inserted is formed, and one of the two mounting seat walls facing each other of the insert mounting seat has a mounting reference hole and a screw. A conical receiving surface having a center line eccentric to the rear end side of the tool body with respect to the center line of the screw hole is formed on the other mounting seat wall surface. A head having a conical outer peripheral surface that can be slidably contacted with the conical receiving surface at one end of the clamp screw and formed at one end of the clamp screw. A first cylinder is formed between the male screw portion and the head, and the outer peripheral surface is in contact with the inner peripheral surface of the attachment reference hole on the tip side of the tool main body between the male screw portion and the head. And a second cylindrical portion whose outer peripheral surface is brought into contact with the inner peripheral surface on the rear end side of the tool main body in the through hole of the insert main body. A first flexible portion having an outer diameter smaller than that of the first and second cylindrical portions is formed between the first and second cylindrical portions.

  In the blade-tip-exchangeable cutting tool configured in this way, when the cutting insert is attached by screwing the clamp screw, the outer peripheral surface of the first cylindrical portion on the male screw portion side of the clamp screw is the tip of the tool body of the attachment reference hole. Since the inner and outer peripheral surfaces are brought into sliding contact with each other, these inner and outer peripheral surfaces act as attachment reference surfaces in the cutting edge-exchangeable cutting tool described in Patent Document 1. For this reason, as with the cutting edge-exchangeable cutting tool described in Patent Document 1, the pressing force of the cutting insert is stabilized, and the cutting insert mounting accuracy with respect to loads in various directions and sizes during cutting processing. Can be maintained with high accuracy, and high processing accuracy can be obtained. Further, the outer peripheral surface of the second cylindrical portion on the head side of the clamp screw presses the through hole of the cutting insert toward the rear end side of the tool body due to the bending of the clamp screw, and the seating surface of the insert body is attached to the insert mounting seat. Press against the seat bottom.

  In the blade-tip-exchangeable cutting tool having the above-described configuration, the first flexible portion having an outer diameter smaller than those of the first and second cylindrical portions is provided between the first and second cylindrical portions. Since the rigidity of the clamp screw can be reduced within a necessary range by forming such a first flexible portion, the clamp screw is bent when the cutting insert is clamped and fixed. Can be made easier. Therefore, the cutting insert can be securely and stably attached to the insert mounting seat even with a small screwing force.

  Moreover, since this 1st flexible part has an outer diameter smaller than the 1st, 2nd circular head, it does not contact with the through-hole of an insert main body, ie, the contact area of a clamp screw and a through-hole. Can be reduced. As a result, the frictional resistance when the clamp screw presses the through hole toward the rear end side of the tool body is also reduced, so that it is possible to prevent a situation in which the insert body moves when the clamp screw is tightened. For this reason, the mounting accuracy of the cutting insert can be further increased, and the processing accuracy can be further improved.

  Furthermore, it is preferable that a second flexible portion having an outer diameter smaller than that of the second cylindrical portion is formed between the second cylindrical portion and the head portion. Thereby, while being able to make a clamp screw bend more easily, a contact area with a through-hole can further be reduced.

  Furthermore, the boundary between the first cylindrical portion and the first flexible portion is an extension of the one mounting seat wall surface of the insert mounting seat in a state in which the clamping screw is screwed and the cutting insert is sandwiched. It is preferable to locate in the mounting reference hole on the surface or from the extended surface. Thereby, since this 1st cylindrical part does not contact the penetration hole of an insert body, when tightening a clamp screw, for example, when the clearance between the 1st cylindrical part and the penetration hole of an insert body is small, It is possible to prevent variation in mounting shake accuracy of the insert body due to contact between the first cylindrical portion and the through hole of the insert body.

  As described above, according to the present invention, it is possible to attach the cutting insert to the insert mounting seat reliably and with high accuracy while stabilizing the pressing force of the cutting insert by the clamp screw. Can be achieved.

It is a side view of the front-end | tip part of the blade-tip-exchange-type cutting tool which shows one Embodiment of this invention. It is ZZ sectional drawing in FIG.

1 and 2 show an embodiment of the present invention. The blade-tip-exchangeable cutting tool of the present embodiment is a blade-tip-exchangeable end mill, particularly a ball end mill, that is, the distal end portion of the tool body 1 having a substantially cylindrical shape centering on the axis O (the left portion in FIGS. 1 and 2). The cutting insert 3 having the insert main body 3b in which the arc-shaped cutting blade 3a is formed is seated on the slit-shaped insert mounting seat 2 formed in (1) and is clamped by the clamp screw 4 (the clamp screw 4 is The cutting insert 3 is detachably attached to the insert mounting seat 2 by fastening the cutting insert 3 to the insert mounting seat 2 by fastening. Such a blade-tip-exchangeable cutting tool is usually fed out in a direction intersecting with the axis O while a shank portion (not shown) on the rear end side of the tool body 1 is gripped by the spindle of the machine tool and rotated around the axis O. The workpiece such as a die is cut by the cutting blade 3a. In the present embodiment, the direction from the shank portion of the tool body 1 toward the insert mounting seat 2 in the direction in which the axis O extends is referred to as the tip side (left side in FIGS. 1 and 2). The direction toward the part is referred to as the rear end side (the right side in FIGS. 1 and 2). A direction orthogonal to the axis O is referred to as a radial direction. Of the radial directions, a direction approaching the axis O is referred to as a radially inner side, and a direction away from the axis O is referred to as a radially outward direction.
Further, in this embodiment, the cutting edge-replaceable cutting tool including the clamp screw 4 having a screw size in the range of M2 to M8 is mainly targeted. Describes the tool. In addition, the screw size of the clamp screw 4 of the blade edge | tip-exchange-type cutting tool of this invention is not limited to the said range.

  The insert body 3b of the cutting insert 3 is formed in a plate shape from a hard material such as cemented carbide, and includes two mutually parallel side surfaces 3c and a seating surface 3d perpendicular to the side surfaces 3c. An arcuate (substantially semicircular) cutting edge 3a protrudes on the outer periphery (tip side and radially outward) of the tip of the tool body 1, and the rotation locus formed around the axis O has a center on the axis O. It is attached to the insert mounting seat 2 so as to be hemispherical. In other words, the insert body 3b is attached to the insert mounting seat 2 so that the center of the arc formed by the cutting edge 3a passes through the axis O. The insert body 3b has a circular through-hole 3e having a center line passing through the approximate center of the arc formed by the cutting edge 3a and penetrating the insert body 3b. The two side surfaces 3c are formed on the two side surfaces 3c. It is open.

  On the other hand, the tool body 1 and the clamp screw 4 are formed of a metal material such as a steel material that is lower in hardness than the insert body 3b and can be elastically deformed. Of these, the tip of the tool body 1 is formed in a hemispherical shape centering on the intersection of the axis O and the center line of the through hole 3e of the insert body 3b with the cutting insert 3 attached. However, the radius of the hemisphere formed by the tip of the tool body 1 is slightly smaller than the radius of the hemisphere formed by the rotation locus of the cutting edge 3a.

  As shown in FIG. 2, the insert mounting seat 2 formed at the tip of the tool body 1 is a tool viewed from a direction perpendicular to the axis O and the center line of the through hole 3e of the insert body 3b. It is formed in the shape of a slit that opens in a U-shape on the front end side of the main body 1, that is, two mounting seat wall surfaces 2a, 2b that are parallel to each other and parallel to the axis O, and these mounting seat wall surfaces 2a, 2b A mounting seat bottom surface 2c that is perpendicular and orthogonal to the axis O and faces the tip end side of the tool body 1 is provided.

  The two mounting seat wall surfaces 2a and 2b are at an equal distance from the axis O, and the interval between these mounting seat wall surfaces 2a and 2b is such that the two side surfaces 3c of the insert body 3b are respectively attached to both mounting seat wall surfaces 2a and 2b. The size is such that the insert body 3b can be fitted in sliding contact. The insert body 3b is thus fitted and the seating surface 3d is brought into contact with the mounting seat bottom surface 2c, so that the cutting insert 3 is seated on the insert mounting seat 2 so that the center line of the through hole 3e is orthogonal to the axis O. Be made.

  Further, as described above, the cutting insert 3 is attached to the first mounting seat wall surface (the lower mounting seat wall surface in FIG. 2) 2a which is one of the two mounting seat wall surfaces 2a and 2b. The mounting reference hole 5 and the screw hole 6 are formed so as to face the opening of the through hole 3e in the side surface 3c of the insert body 3b that is slidably contacted with the first mounting seat wall surface 2a while being seated on the seat 2. Has been. In the present embodiment, the attachment reference hole 5 is formed so as to open in the attachment seat wall surface 2a, and the screw hole 6 is formed in the bottom (radially outward) of the attachment reference hole 5.

  Among these, the screw hole 6 extends so that the center line L1 thereof is orthogonal to the axis O. Further, the attachment reference hole 5 has a long hole shape (track shape) extending in the direction of the axis O, that is, in the cross section parallel to the attachment seat wall surface 2a, one circle is divided in the axis O direction by its diameter. It is formed in a shape in which two semicircles are connected by a square (square) having a width equal to this diameter. Of these semicircles, the center of the semicircle located on the tip side of the tool body 1 is located on the center line L1 of the screw hole 6, and the semicylindrical surface of the mounting reference hole 5 along this semicircle on the tip side. The inner peripheral surface is a mounting reference surface 5a on the tool body 1 side. Note that the inner diameters of these semicircles (the diameter of the one circle) are slightly larger than the inner diameters of the screw holes 6 (the diameters of the screw valleys of the screw holes 6).

  On the other hand, a second mounting seat wall surface 2b (the upper mounting seat wall surface in FIG. 2) that is the other mounting seat wall surface of the two mounting seat wall surfaces 2a and 2b is provided on the second mounting seat wall surface 2b. A concave conical hole 7 having an inner diameter that gradually increases toward the outer peripheral side of the tip end of the tool body 1 (upper side in FIG. 2, radially outward) is formed on the outer peripheral surface of the tool body 1. Yes. In the cross section of the tool body 1 parallel to the mounting seat wall surface 2b, the concave conical hole 7 is formed in a circular shape, and as the inner diameter of this circle moves toward the outer peripheral side (radially outward) of the tool body 1. Gradually increases.

  Furthermore, the semiconical surface along the semicircle on the tip side of the tool body 1 of the concave conical hole 7 is a conical receiving surface 7a in the present embodiment, and the center line L2 of the conical receiving surface 7a is It is orthogonal to the axis O and is slightly eccentric to the rear end side of the tool body 1 with respect to the center line L1 of the screw hole 6. The center line L2 is parallel to the center line L1. A slot having a larger inner diameter than the mounting reference hole 5 is provided between the hole bottom of the concave conical hole 7 (the radially inner end of the concave conical hole 7) and the second mounting seat wall surface 2b. 7 b is formed continuously with the concave conical hole 7. The long hole portion 7b is a square having a width equal to the diameter between two semicircles obtained by dividing one circle (a circle having a diameter larger than the diameter of the semicircle of the mounting reference hole 5) by the diameter in the direction of the axis O. It is formed in a shape connected by. The midpoint of the center of the two semicircles of the long hole portion 7 b is located on the center line L <b> 1 of the screw hole 6. The long hole portion 7b opens in the second mounting seat wall surface 2b so as to face the opening portion of the through hole 3e in the side surface 3c of the insert main body 3b in sliding contact with the second mounting seat wall surface 2b.

  The clamp screw 4 is formed with a male screw portion 4a that is screwed into the screw hole 6 at one end (lower portion in FIG. 2), and a male screw at the other end (upper portion in FIG. 2). When the portion 4a is screwed into the screw hole 6, a head portion 4b having a conical outer peripheral surface that is slidable in contact with the conical receiving surface 7a and gradually increases in diameter toward the other end side is formed. ing. Further, an engagement hole 4c that engages with a work tool such as a wrench when the clamp screw 4 is screwed or loosened is formed on the end face of the head 4b.

  Further, a first cylindrical portion 4d is formed between the male screw portion 4a and the head portion 4b on one end side where the male screw portion 4a is provided. The first cylindrical portion 4d has a cylindrical surface whose outer peripheral surface is centered on the center line of the clamp screw 4, and its outer diameter is slightly larger than the outer diameter of the male screw portion 4a. The reference hole 5 is set to be slightly smaller than the inner diameter of the inner peripheral surface on the front end side which is the mounting reference surface 5a. As described above, when the male screw portion 4a is screwed into the screw hole 6, the outer peripheral surface of the first cylindrical portion 4d can be brought into sliding contact with the attachment reference surface 5a. In the present embodiment, a connection portion including an incomplete screw portion is provided between the first cylindrical portion 4d and the male screw portion 4a. The connecting portion is preferably smaller than the root diameter of the male screw portion 4a, and has an outer diameter smaller than outer diameters of first and second flexible portions 4f and 4g described later.

  On the other hand, on the other end side where the head 4b is provided between the male screw 4a and the head 4b (between the first cylindrical portion 4d and the head 4b), the center line direction of the clamp screw 4 is provided. A second cylindrical portion 4e is formed at a distance from the first cylindrical portion 4d. The outer peripheral surface of the second cylindrical portion 4e also has a cylindrical surface shape centered on the center line of the clamp screw 4, and the outer diameter thereof is set equal to that of the first cylindrical portion 4d. Further, the length of the second cylindrical portion 4e in the center line direction of the clamp screw 4 is set longer than the first cylindrical portion 4d in the present embodiment. Note that the preferable range of the length of the first cylindrical portion 4 d in the center line direction of the clamp screw 4 varies depending on the screw size of the clamp screw 4. For example, when the screw size of the clamp screw 4 is M8 as in this embodiment, the length of the first cylindrical portion 4d is preferably 10 to 50% of the length of the second cylindrical portion 4e. Although it is preferable that it is -40%, it is not limited to this.

  And between these 1st, 2nd cylindrical parts 4d and 4e, the 1st flexible part 4f whose outer diameter is smaller than the 1st and 2nd cylindrical parts 4d and 4e is formed. Furthermore, in the present embodiment, a second flexible portion 4g having an outer diameter smaller than that of the second cylindrical portion 4e is formed between the second cylindrical portion 4e and the head 4b of the clamp screw 4. Yes. The first and second flexible portions 4f and 4g also have cylindrical surfaces whose outer peripheral surfaces are centered on the center line of the clamp screw 4. In this embodiment, the outer diameters (diameters) are equal to each other. The difference in outer diameter (diameter) between the first and second cylindrical portions 4d and 4e is, for example, about 0.08 to 0.5 mm. In the present embodiment, the length of the second flexible portion 4g in the center line direction of the clamp screw 4 is set longer than that of the first flexible portion 4f.

  In addition, the boundary between the first cylindrical portion 4d and the first flexible portion 4f is formed by screwing the clamp screw 4 (by screwing the male screw portion 4a of the clamp screw 4 into the screw hole 6) and cutting the cutting insert 3. In a state of being sandwiched between the insert mounting seats 2, as shown in FIG. 2, the insert mounting seat 2 is located on the extension surface of the first mounting seat wall surface 2a or from the extension surface within the mounting reference hole 5. . Furthermore, in the present embodiment, the center of the second cylindrical portion 4e in the center line direction of the clamp screw 4 is the same as that of the insert body 3b in the state where the clamp screw 4 is screwed and the cutting insert 3 is sandwiched between the insert mounting seats 2. It is set so as to be substantially positioned on the center in the thickness direction, that is, on the axis O of the tool body 1. As described above, between the male screw portion 4a and the head portion 4b of the clamp screw 4 of the present embodiment, the connecting portion, the first cylindrical portion 4d, and the first allowable portion in the central axis direction of the clamp screw 4. The flexible portion 4f, the second cylindrical portion 4e, and the second flexible portion 4f are sequentially provided from the male screw portion 4a side.

  The through hole 3e of the insert main body 3b is a screw hole in which the male screw portion 4a is screwed in a state where the seating surface 3d is brought into contact with the mounting seat bottom surface 2c and the insert main body 3b is seated on the insert mounting seat 2 as described above. 6 starts to be screwed, so that a very slight gap is provided between the outer peripheral surfaces of the first and second cylindrical portions 4d, 4e and the inner peripheral surface of the rear end side portion of the tool body 1 of the through hole 3e. The position of the center line and the inner diameter of the through hole 3e are set. In the present embodiment, the inner diameter of the through hole 3 e is substantially the same as the inner diameter of the attachment reference hole 5.

  Such a blade-tip-exchangeable cutting tool fits the cutting insert 3 as described above into the insert mounting seat 2 so that the center line of the through hole 3e of the insert main body 3b is orthogonal to the axis O, and the seating surface 3d is formed. Assembling is carried out by contacting the mounting seat bottom surface 2c and then inserting the clamp screw 4 from the concave conical hole 7 into the through hole 3e and screwing the male screw portion 4a into the screw hole 6.

  When the male screw portion 4a starts to be screwed into the screw hole 6, the center line of the clamp screw 4 is coaxial with the center line L1 of the screw hole 6, but the outer peripheral surface of the head 4b of the clamp screw 4 is the concave conical hole 7 Since the center line L2 of the conical receiving surface 7a is slightly offset from the center line L1 of the screw hole 6 toward the rear end side of the tool body 1, the clamp screw 4 is The head 4b begins to bend so that it falls into the rear end side of the tool body 1.

  When the clamp screw 4 is bent in this manner, the outer peripheral surface of the second cylindrical portion 4e on the other end side (head 4b side) is on the rear end side of the tool body 1 of the through hole 3e of the cutting insert 3. The insert main body 3b is pressed against the mounting seat bottom surface 2c of the insert mounting seat 2 while contacting the inner peripheral surface. At the same time, the head 4b of the clamp screw 4 is pressed against the conical receiving surface 7a, so that the interval between the two mounting seat wall surfaces 2a, 2b of the insert mounting seat 2 is narrowed, and the two of the insert body 3b The side surface 3c is pressed, and the cutting insert 3 is clamped and fixed to the insert mounting seat 2 by these presses.

  Here, when the clamp screw 4 starts to bend, the outer peripheral surface of the first cylindrical portion 4d is in sliding contact with the mounting reference surface 5a on the tip end side of the tool body 1 of the mounting reference hole 5, so that the clamp screw 4 The head 4b is bent so that the head 4b side is inclined toward the rear end side of the tool body 1 with a portion slidably in contact with the mounting reference surface 5a on the outer peripheral surface of the cylindrical portion 4d. That is, the portion of the first cylindrical portion 4d that is in sliding contact with the attachment reference surface 5a acts as an attachment reference surface on the clamp screw 4 side, and the clamp screw 4 is attached to the tool body 1 by the attachment reference surface 5a on the tool body 1 side. Since the front end side and the outer peripheral side (outward in the radial direction) are restrained, the cutting insert 3 is firmly held on the insert mounting seat 2 regardless of the load applied from the cutting edge 3a to the cutting insert 3 during cutting. can do.

  Further, in the cutting edge-exchangeable cutting tool having the above-described configuration, the outer diameter of the clamp screw 4 between the first and second cylindrical portions 4d and 4e is smaller than those of the first and second cylindrical portions 4d and 4e. One flexible portion 4f is formed. For this reason, since the rigidity of the first flexible portion 4f can be reduced in a necessary range as compared with the first and second cylindrical portions 4d and 4e, the clamp screw 4 can be easily bent. The length of the first flexible portion 4 f in the center line direction of the clamp screw 4 that can sufficiently obtain such an effect varies depending on the screw size of the clamp screw 4. For example, when the screw size of the clamp screw 4 is M8 as in this embodiment, the length of the first flexible portion 4f is preferably 100 to 500% of the length of the first cylindrical portion 4d. Although it is preferable that it is 200 to 400%, it is not limited to this.

  In addition, since the first flexible portion 4f is adjacent to the first cylindrical portion 4d serving as a fulcrum of bending of the clamp screw 4 as described above, the clamp screw 4 can be further easily bent. Accordingly, by engaging a work tool such as a wrench in the engagement hole 4c and rotating the clamp screw 4, the screwing force when the male screw portion 4a is screwed into the screw hole 6 can be kept small, and the clamp screw 4 can be securely bent, and the cutting insert 3 can be stably fixed to the insert mounting seat 2.

  Further, since the first flexible portion 4f has a smaller outer diameter than the second cylindrical portion 4e contacting the through hole 3e of the insert main body 3b, the first flexible portion 4f does not come into contact with the through hole 3e. The contact area with the through hole 3e is reduced. For this reason, the frictional resistance between the clamp screw 4 and the through hole 3e when the clamp screw 4 abuts the through hole 3e and presses the insert body 3b toward the rear end side of the tool body 1 can be suppressed. The insert body 3b can be prevented from shifting when the clamp screw 4 is tightened immediately before the cutting insert 3 is completely fixed, and the cutting insert 3 is attached to the insert mounting seat 2 with higher accuracy. The accuracy can be improved.

  Further, in the present embodiment, a second flexible portion 4g having a smaller outer diameter than the second cylindrical portion 4e is also formed between the second cylindrical portion 4e and the head portion 4b of the clamp screw 4. Yes. Therefore, the clamp screw 4 can be more easily bent by the second flexible portion 4g, and the contact area with the through hole 3e of the insert main body 3b can be further reduced to further reduce the frictional resistance.

  And the 2nd flexible part 4g which does not contact the through-hole 3e between the 2nd cylindrical part 4e of the other end side (head 4b side) and the head 4b of the clamp screw 4 is formed in this way. Thus, the outer peripheral surface of the second cylindrical portion 4e penetrates due to the bending of the clamp screw 4 as compared with the case where the entire portion between the male screw portion 4a and the head portion 4b is a cylindrical portion that contacts the through hole 3e. The position in contact with the hole 3e can be brought closer to the outer peripheral surface of one end portion side (the male screw portion 4a side) of the first cylindrical portion 4d that is the attachment reference surface of the clamp screw 4. Therefore, even if the bending amount of the clamp screw 4 is the same, the pressing force acting on the position where the second cylindrical portion 4e contacts the through-hole 3e can be increased with the outer peripheral surface on the one end side as a fulcrum. The cutting insert 3 can be fixed to the insert mounting seat 2.

  In the present embodiment, the center of the second cylindrical portion 4e in the center line direction of the clamp screw 4 is the thickness of the insert body 3b in a state where the clamp screw 4 is screwed and the cutting insert 3 is sandwiched between the insert mounting seats 2. It is set so as to be approximately located at the center of the direction. For this reason, the cutting insert 3 can be pressed in a well-balanced manner in the thickness direction of the insert body 3b (the left-right direction in FIG. 2), and can be more stably fixed to the insert mounting seat 2. Note that the preferable range of the length of the second cylindrical portion 4 e in the center line direction of the clamp screw 4 varies depending on the screw size of the clamp screw 4. For example, when the screw size of the clamp screw 4 is M8 as in this embodiment, the length of the second cylindrical portion 4e is 30 to 70% of the thickness of the insert body 3b (distance between the two side surfaces 3c). Although it is preferable that it is 40 to 60%, it is not limited to this.

  However, for example, the outer diameter of the clamp screw 4 is originally small, and the clamp screw 4 can be sufficiently bent only by the first flexible portion 4f, or the contact area with the through hole 3e can be reduced. In this case, the second flexible portion 4g may not be formed, and the second cylindrical portion 4e may extend to the other end side as it is and continue to the head portion 4b. Conversely, three or more flexible portions may be formed between the male screw portion 4a and the head portion 4b of the clamp screw 4.

  On the other hand, in the present embodiment, the boundary between the first cylindrical portion 4d and the first flexible portion 4f is inserted into the insert mounting seat 2 in a state in which the clamp screw 4 is screwed and the cutting insert 3 is sandwiched between the insert mounting seats 2. The first mounting seat wall surface 2a is positioned on the extended surface of the first mounting seat wall 2a or in the mounting reference hole 5 from the extended surface. For this reason, the first cylindrical portion 4d does not come into contact with the through hole 3e.

  When the clamp screw 4 is screwed in, a clearance is secured between the through hole 3e and the first flexible portion 4f, so that the tool body of the outer peripheral surface of the first flexible portion 4f It is possible to avoid the portion facing the tip end side from coming into contact with the through hole 3e. Therefore, by avoiding this contact, it is possible to prevent the insert main body 3b from rotating about the through-hole 3e and causing variations in mounting deflection accuracy.

  The angle formed by the concave conical hole 7, the center line L2, and the inner peripheral surface that can sufficiently obtain the above-described effect by appropriately bending the clamp screw 4 varies depending on the screw size of the clamp screw 4. For example, when the screw size of the clamp screw 4 is M8 as in this embodiment, the angle is preferably 10 to 40 °, and more preferably 15 to 35 °. Further, in the state where the clamp screw 4 is screwed and the cutting insert 3 is sandwiched between the insert mounting seats 2, the concave conical hole 7 in the region where the conical receiving surface 7 a contacts the outer peripheral surface of the head 4 b of the clamp screw 4. A preferable range of the length in the direction of the center line L2 also varies depending on the screw size of the clamp screw 4. For example, when the screw size of the clamp screw 4 is M8 as in the present embodiment, this length is preferably 5 to 45% of the length of the clamp screw 4 and more preferably 15 to 35%.

  In the present embodiment, the case where the present invention is applied to a blade end replaceable ball end mill in which the rotation locus of the cutting blade 3a of the cutting insert 3 is hemispherical has been described. Is a bottom blade extending in a direction substantially perpendicular to the axis O, and an outer periphery whose rotation trajectory around the axis O is connected to the outer peripheral end (radially outer end) of the bottom blade to form a cylindrical surface centered on the axis O. The present invention can also be applied to a square end mill composed of blades and a radius end mill in which arc-shaped corner blades are formed at the corners where the bottom blades and outer peripheral blades intersect. Further, the present invention may be applied to a cutting tool other than the end mill, for example, a blade-tip exchange type drill.

  Next, when the boundary between the first cylindrical portion 4d and the first flexible portion 4f described above is inserted into the insert mounting seat 2 with the clamp screw 4 screwed in, the insert mounting seat 2 has a first boundary. The effect of being located on the extended surface of one mounting seat wall surface 2a or in the mounting reference hole 5 from this extended surface will be described with examples. In this example, the clamp screw 4 based on the above embodiment is manufactured, and the cutting blade 3a of the insert body 3b when the cutting insert 3 is first attached to the insert mounting seat 2 of the tool body 1 by the clamp screw 4 is used. The operation of measuring the position accuracy to the reference value, and then removing the cutting insert 3 after loosening the clamp screw 4 and then attaching the cutting insert 3 again is taken as one cycle, and the cutting at the 10th, 100th and 200th cycles The mounting runout accuracy of the insert 3 was measured and compared with a reference value.

  Here, the clamp screw 4 in this embodiment has a male screw portion 4a of a secondary screw having an M8 × 0.75 mm, the diameters of the first and second cylindrical portions 4d and 4e are 8 mm, and the first and second allowable screws. The flexures 4f and 4g had a diameter of 7.7 mm, the maximum diameter of the head 4b was 12 mm, and the minimum diameter was 7.7 mm. The length of the first cylindrical portion 4d in the center line direction of the clamp screw 4 is 1 mm, the length of the first flexible portion 4f is 3.08 mm, the length of the second cylindrical portion is 3.6 mm, and the second The length of the flexible part 4g was 1.6 mm, and the length of the head part 4b was 7.9 mm. The inclination angle of the conical outer peripheral surface of the head 4b with respect to the center line direction of the clamp screw 4 was 20 °. Further, in the cutting insert 3, the thickness between the two side surfaces 3c of the insert body 3b is 7.2 mm, the radius of the arcuate cutting edge 3a is 15 mm, and the diameter of the through hole 3e is 8.008 mm in actual measurement. It was. The reference mounting surface 5a of the tool body 1 has the above-described track shape, and the diameter of the semicircle forming the track shape is also 8.008 mm in actual measurement. In the state where the clamp screw 4 is screwed and the cutting insert 3 is sandwiched between the insert mounting seats 2, the boundary between the first cylindrical portion 4 d and the first flexible portion 4 f of the clamp screw 4 is that of the insert mounting seat 2. It was located in the attachment reference hole 5 slightly from the extended surface of the first attachment seat wall surface 2a.

  Note that the mounting runout accuracy of the cutting insert 3 is on a straight line that passes through the center of the arcuate cutting edge 3a in FIG. 1 when the cutting insert 3 is first mounted by the clamp screw 4 and is perpendicular to the axis O of the tool body 1. The interval between both ends of the cutting edge 3a was used as a reference value, and the difference from the reference value of the interval at the 10th, 100th, and 200th cycles was measured. Moreover, as a comparative example with respect to the above-described embodiment, a single cylindrical portion having a diameter of 8 mm as a whole between the male screw portion and the head, like a fastening member of a cutting edge exchangeable cutting tool described in Patent Document 1, Using the clamped screw, the cycle of holding the same cutting insert 3 as described above and then removing it was repeated, and the intervals at the 10th cycle, 100th cycle and 200th cycle were measured, and the first cycle serving as the reference value was measured. The difference from the above interval was defined as the mounting runout accuracy of the cutting insert 3.

  As a result, in the comparative example, the difference from the reference value in the 10th cycle is 1 μm, the difference in the 100th cycle is 12 μm, the difference in the 200th cycle is 11 μm, and the operation of attaching and removing the cutting insert 3 is repeated. As a result, it was recognized that the mounting runout accuracy varied. On the other hand, in the embodiment, the difference from the reference value at the 10th cycle is 0 μm, and no variation is observed. The difference from the reference value at the 100th and 200th cycles is 1 μm, and the mounting runout accuracy is It was found that the variation of was suppressed.

  According to the cutting edge-exchangeable cutting tool of the present invention, the clamp screw can be easily bent while stabilizing the pressing force of the cutting insert, and the cutting insert can be prevented from being displaced during tightening.

DESCRIPTION OF SYMBOLS 1 Tool main body 2 Insert mounting seat 2a, 2b Mounting seat wall surface 2c Mounting seat bottom surface 3 Cutting insert 3a Cutting blade 3b Insert main body 3c Side surface 3d Seating surface 3e Through-hole 4 Clamp screw 4a Male thread part 4b Head part 4c Engagement hole 4d 1st 1 cylindrical portion 4e second cylindrical portion 4f first flexible portion 4g second flexible portion 5 mounting reference hole 5a mounting reference surface 6 screw hole 7 concave conical hole 7a conical receiving surface 7b long hole portion O Axis line of tool body 1 L1 Center line of screw hole 6 L2 Center line of conical receiving surface 7a

Claims (3)

Cutting edge replacement that allows a cutting insert having an insert body formed with a cutting edge to be seated on a slit-like insert mounting seat formed at the tip of the tool body and detachably attached by clamping with a clamp screw Type cutting tool,
The insert body is formed with a seating surface capable of contacting the mounting seat bottom surface of the insert mounting seat, and a through hole through which the clamp screw is inserted through the insert body.
Of the two mounting seat wall surfaces of the insert mounting seat facing each other, one mounting seat wall surface is formed with a mounting reference hole and a screw hole, and the other mounting seat wall surface has a center line of the screw hole. A conical receiving surface having a center line eccentric to the tool body rear end side is formed on the tool body tip side,
A male screw portion to be screwed into the screw hole is formed at one end portion of the clamp screw, and a head portion having a conical outer peripheral surface capable of sliding contact with the conical receiving surface is formed at the other end portion.
Between these male screw parts and the head, a first cylindrical part is formed on the male screw part side so that the outer peripheral surface is in contact with the inner peripheral surface of the attachment reference hole on the tip side of the tool body. At the same time, a second cylindrical portion whose outer peripheral surface is brought into contact with the inner peripheral surface on the rear end side of the tool main body in the through hole of the insert main body is formed on the head side. A blade-tip-exchangeable cutting tool, wherein a first flexible portion having an outer diameter smaller than that of the first and second cylindrical portions is formed between the cylindrical portions.   The second flexible part having an outer diameter smaller than that of the second cylindrical part is formed between the second cylindrical part and the head part. Replaceable cutting tool.   The boundary between the first cylindrical portion and the first flexible portion is an extension surface of the one mounting seat wall surface of the insert mounting seat in a state in which the clamping screw is screwed and the cutting insert is sandwiched. Alternatively, the cutting edge exchangeable cutting tool according to claim 1 or 2, wherein the cutting tool is located in the attachment reference hole from the extended surface.

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