JP2011062787A - Head exchange type cutting tool - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To easily detach and exchange a cutting head even when the cutting head is strongly screwed to a holder or strongly fastened to an attaching hole. <P>SOLUTION: In the cutting head 1 having a cutting edge 3 provided in an end part, a rear end part of the cutting head 1 is inserted into an opening part of one end of the attaching hole 11 passing through the holder 10. A screw part 6 formed in the rear end part is screwed to an intermediate member 14 accommodated in the other end than the opening part of the one end of the attaching hole 11 so as to be detachable. An outer peripheral surface of the rear end part of the cutting head 1 and an inner peripheral surface of the opening part of one end of the attaching hole 11 are formed in a conical surface shape on a central axis O of the attaching hole the diameters of which are gradually reduced as they go to the other end of the attaching hole 11 so as to come close to each other. The intermediate member 14 freely moves forward and backward in the direction of the central axis O of the attaching hole 11 and restricts a rotation on the central axis O of the attaching hole 11 to screw an attaching bolt 15 having a head part 15B inserted from the other end of the attaching hole 11 to the intermediate member 14. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to a head exchangeable cutting tool in which a cutting head provided with a cutting blade is detachably attached to a holder in which a mounting hole is formed.

  As such a head replaceable cutting tool, for example, in Patent Documents 1-3 and the like, a cutting head provided with a cutting edge at a tip of a holder in which a mounting hole is formed has a rear end thereof at one end side of the mounting hole. The one that is inserted into the opening and mounted has been proposed. Here, in the head replaceable cutting tool described in these Patent Documents 1-3, the outer peripheral surface of the rear end portion of the cutting head and the inner peripheral surface of the one end side opening portion of the mounting hole are the other end side of the mounting hole ( A conical surface is formed around the center line of the attachment holes that can be brought into close contact with each other and gradually reduce in diameter toward the rear end side of the holder.

  Among these, in the cutting tool described in Patent Document 1, a male screw portion is formed on the further rear end side of the conical surface of the cutting head rear end portion, and the other end side of the mounting hole inner peripheral surface. Is formed with a female screw portion, and in the cutting tool described in Patent Document 2, a bolt having a female screw portion formed at the rear end of the cutting head and a male screw portion formed at the other end of the mounting hole is provided. In both cases, the male and female screw portions are screwed together and the cutting head is screwed in, so that the inner and outer peripheral surfaces of the conical surface are brought into close contact with each other, and the cutting head is attached to the tip of the holder by taper fitting. .

  On the other hand, in the cutting tool described in Patent Document 3, a retracting member is accommodated on the other end side of the inner peripheral surface of the mounting hole in the shape of a conical surface, and connected to the hook portion at the rear end of the cutting head. By rotating the retracting member, the outer peripheral surface of the rear end portion of the cutting head having a conical surface is formed by screwing the male screw portion formed at the rear end portion of the retracting member into the female screw portion formed in the mounting hole. And the inner peripheral surface of the mounting hole are in close contact with each other, and the cutting head is fixed to the holder tip by taper fitting.

Japanese Patent Laid-Open No. 7-164234 US Pat. No. 6,394,711 JP 2004-98272 A

  In such a head replaceable cutting tool, even if it is a turning tool such as an end mill that performs cutting with the above-mentioned cutting blade by being rotated around the center line of the mounting hole, it usually acts on the cutting head during cutting. Since the tool rotates in the direction in which the male and female screw parts are tightened by the cutting force to be cut, these male and female screw parts do not loosen. However, for example, if a cutting force more than expected acts on the cutting head due to, for example, a chipping of the cutting edge, the male and female screw parts are too tight, and it is difficult to loosen the screw in order to replace the cutting head in which the chipping has occurred There is a risk of becoming.

  In such a head-exchangeable cutting tool, the cutting head for cutting the work material with the cutting blade is formed of a hard material such as cemented carbide, and the holder is relatively inexpensive and easy to form a screw portion or the like. Generally, it is made of steel material such as alloy steel. However, in the case of such a combination of cutting head and holder material, the holder has a higher coefficient of thermal expansion. When the temperature rises, the holder expands more than the cutting head, and the taper fitting pressure decreases. As a result, the cutting head rotates in the screwing direction and the male and female screw portions are further tightened. And when cutting is finished and the temperature of the tool is lowered, the holder contracts more than the cutting head, so that the taper fitting pressure is increased and the cutting head is firmly tightened in the mounting hole. It will be difficult to remove.

  The present invention has been made under such a background. Even if the threaded portion of the cutting head is strongly screwed into the threaded portion on the holder side or the cutting head is firmly tightened in the mounting hole, this cutting is performed. An object of the present invention is to provide a head exchangeable cutting tool in which the head can be easily removed and replaced.

  In order to solve the above problems and achieve such an object, according to the present invention, a cutting head provided with a cutting edge at a tip end in an attachment hole formed so as to penetrate a holder has a rear end portion thereof. The screw hole formed at the rear end of the mounting hole is inserted into the opening at one end of the mounting hole, and is screwed to the intermediate member housed at the other end of the mounting hole at the other end. A head exchangeable cutting tool attached in a detachable manner, wherein the outer peripheral surface of the rear end portion of the cutting head and the inner peripheral surface of the one end side opening portion of the mounting hole are directed toward the other end side of the mounting hole. The conical surface is centered on the mounting hole center lines that can gradually come into close contact with each other, and the intermediate member is movable back and forth in the direction of the mounting hole center line, and the rotation around the mounting hole center line is restricted. The intermediate member has a head and has a mounting hole. Wherein the inserted mounting bolt from the end side is brought screwed.

  In the head replaceable cutting tool configured as described above, the intermediate member can be moved back and forth in the direction of the center line of the mounting hole, and the rotation around the center line is restrained and accommodated in the mounting hole. Further, by screwing a mounting bolt having a head and inserted from the other end side of the mounting hole, the intermediate member is fastened to the mounting bolt and fixed in the mounting hole of the holder. Therefore, by inserting the rear end portion of the cutting head into the opening on one end side of the mounting hole and screwing the screw portion formed at the rear end portion into the intermediate member and screwing it in, conical surface shapes that can be brought into close contact with each other The outer peripheral surface of the rear end portion of the cutting head and the inner peripheral surface of the one end side opening of the mounting hole are taper-fitted, and the cutting head is fixed to the holder to constitute the cutting tool.

  When cutting is performed with the head exchangeable cutting tool thus configured, the threaded portion of the cutting head is strongly screwed into the intermediate member, or the cutting head rear end is caused by the difference in thermal expansion coefficient between the cutting head and the holder. When it becomes difficult to remove the cutting head because the part is tightened in the mounting hole, the intermediate bolt is rotated together with the cutting head by rotating the mounting bolt in a direction in which the screwing with the intermediate member is loosened. It is possible to remove the cutting head by releasing the taper fitting by pushing and moving to one end side.

  Also, if this taper fit is too strong and cannot be solved by simply rotating the mounting bolt, if the mounting bolt is rotated in the loosening direction, its head will protrude from the other end of the mounting hole. By hitting this head with a hammer or the like, by applying an impact toward the one end side of the mounting hole to the cutting head via the mounting bolt and the intermediate member, the taper fitting is released to project the cutting head, It can also be removed. At this time, the head of the mounting bolt comes into contact with the end face of the holder at the periphery of the opening on the other end side of the mounting hole, so that the projection of the cutting head is restricted. Therefore, the cutting head pops out and hits the surrounding area. Can also be prevented.

  Here, an end surface facing the one end side of the mounting hole in the head of the mounting bolt and an inner peripheral surface of the opening on the other end side of the mounting hole are gradually reduced in diameter toward the one end side of the mounting hole. By adopting a conical surface centered on the center line of the mounting hole that can be in close contact, when the intermediate member is mounted with a mounting bolt, these conical surfaces are in close contact with each other, and a taper fit similar to that of the cutting head and the mounting hole is used. Since the member and the mounting bolt are fixed, the mounting stability can be improved. However, when removing the cutting head, to loosen the mounting bolt with a smaller force and move the intermediate member and the cutting head, the head end surface of these mounting bolts and the inner peripheral surface of the other end side opening of the mounting hole are The inclination angle formed with respect to the mounting hole center line is larger than the inclination angle formed between the outer peripheral surface of the rear end portion of the cutting head and the inner peripheral surface of the opening on one end side of the mounting hole with respect to the mounting hole center line. It is desirable that

  In addition, the inclination angle between the head end surface of the mounting bolt and the inner peripheral surface of the opening on the other end side of the mounting hole with respect to the mounting hole center line is such that the cutting head rear end outer peripheral surface and the mounting head When the inner peripheral surface of the opening on one end side of the hole is larger than the inclination angle formed with respect to the center line of the mounting hole, the outer peripheral surface of the rear end portion of the cutting head and the opening on the one end side of the mounting hole The inclination angle formed by the inner peripheral surface with respect to the center line of the mounting hole is in the range of 2 ° to 30 °, the end surface of the mounting bolt head facing the one end side of the mounting hole, and the mounting hole. The inclination angle formed by the inner peripheral surface of the end opening with respect to the mounting hole center line is preferably in the range of 20 ° to less than 90 °. When the inclination angle formed by the inner peripheral surface of the end opening is less than 20 °, the outer peripheral surface of the head, the inner peripheral surface of the mounting hole, The taper fitting becomes too strong, and it may be difficult to rotate the mounting bolt itself when removing the cutting head. Further, if the inclination angle formed by the outer peripheral surface of the rear end portion of the cutting head and the inner peripheral surface of the opening on the one end side of the mounting hole is less than 2 °, the taper fitting becomes too strong and it is more difficult to remove the cutting head. On the other hand, if the inclination angle exceeds 30 °, the taper fitting becomes insufficient and the cutting head cannot be firmly attached.

  On the other hand, the end surface facing the one end side of the mounting hole at the head of the mounting bolt and the end surface of the holder at the other end opening peripheral edge of the mounting hole facing the end surface are conical as described above. In other words, the flat surface perpendicular to the center line of the mounting hole, that is, the inclination angle may be set to 90 ° so that they can be in close contact with each other. In this case, since the head of the mounting bolt and the opening at the other end of the mounting hole are not tapered, the mounting bolt can be rotated with a smaller force.

  As described above, according to the present invention, an unexpected cutting force acts on the cutting head and the screw portion is strongly screwed into the screw portion on the holder side, or the cutting is performed after the end of cutting depending on the coefficient of thermal expansion. Even if the head is firmly tightened in the mounting hole, the cutting head can be easily removed by rotating the mounting bolt or by applying an impact to the cutting head via the mounting bolt and the intermediate member. The labor and time required for exchanging the cutting head can be reduced.

It is a side view which shows one Embodiment of this invention. It is a sectional side view of the embodiment shown in FIG. (A) is ZZ sectional drawing in FIG. 1, (b) is a perspective view of the intermediate member in embodiment shown in FIG. It is a figure which shows the modification of embodiment shown in FIG. 1, Comprising: (a) is a figure equivalent to ZZ sectional drawing in FIG. 1, (b) is a perspective view of the intermediate member in this modification. 2A and 2B are diagrams showing another modification of the embodiment shown in FIG. 1, in which FIG. 1A corresponds to the ZZ cross-sectional view in FIG. 1, and FIG. 2B is a perspective view of an intermediate member in the other modification. .

  1 to 3 show an embodiment of the present invention. In the present embodiment, the cutting head 1 has an axial shape centered on the axis C, and the tip portion (the left side portion in FIGS. 1 and 2) is a cutting edge portion 2 having a large outer diameter. A flat cut-out surface parallel to an axis C with which a work tool such as a spanner is engaged is formed on the outer peripheral surface of the rear end side (right side in FIGS. 1 and 2) of the cutting blade portion 2 that is formed. At least a pair of 4 is formed at equal intervals in the circumferential direction. The cutting edge 3 in the present embodiment is a ball end mill-like cutting edge whose hemispherical rotation trajectory around the axis C, but is a square end mill-like cutting edge or a radius end mill-like cutting edge. May be.

  On the other hand, in the rear end portion of the cutting head 1, in order from the rear end side to the rear end side, a position that is reduced in diameter by one step in the radial direction from the rear end of the cutting blade portion 2 through a step surface perpendicular to the axis C is provided. A truncated cone-shaped tapered portion 5 centering on an axis C formed so that the outer peripheral surface is gradually reduced in diameter as it goes, and an axis C having a smaller diameter than the outer diameter of the rear end of the tapered portion 5. And a threaded portion 6 centering on. Here, the inclination angle α formed by the outer peripheral surface of the taper portion 5 with respect to the axis C is preferably in the range of 2 ° to 30 °, more preferably in the range of 2 ° to 20 °. In the embodiment, the angle is about 4 °.

  The screw portion 6 is a male screw portion, and extends to the rear end side in a direction shorter than the taper portion 5 in the axis O direction. Here, the threaded portion 6 is formed, for example, by forming the entire cutting head 1 from a hard material such as cemented carbide, cermet, ceramics, high-speed tool steel, or the like, and subjecting the rear end portion to electric discharge machining or the like. The cutting blade portion 2 and the taper portion 5 may be integrally formed. For example, the cutting blade portion 2 and the taper portion 5 of the cutting head 1 are formed as a cutting head body by the hard material such as cemented carbide. It is formed in one piece, and is provided in the cutting head 1 by connecting a connecting member made of a metal material softer than the cutting head main body such as a steel material on which the screw portion 6 is formed. May be.

  Further, in order to connect such a connecting member to the cutting head main body, it is possible to join it by brazing or the like. For example, the cutting head main body has an axis line from the rear end surface of the tapered portion 5 toward the front end side. A connecting hole is formed along C, and a tip end shaft portion to be inserted into the connecting hole is formed on the tip end side of the screw portion 6, and is extended from the rear end of the screw portion 6 to the tip end shaft portion. A hole is formed along the center line, and a recess is formed in an inner peripheral surface of the connection hole in a range where the hole is formed in the center line direction, and the connection member is connected to the tip shaft. The outer peripheral part of the part may be in close contact with the inner peripheral surface of the connecting hole, and a part of the outer peripheral part may protrude and be fitted into the concave part to be connected to the cutting head body. In this case, it is desirable that at least one of the wall portion facing the front end side in the center line direction and the wall portion facing the circumferential direction around the center line be formed in the recess. A planar wall surface extending in the center line direction may be formed in the connecting hole, and the wall surface may be a wall portion facing the circumferential direction around the center line in the recess.

  In addition, a hole is formed in the connecting member so as to extend from the threaded portion 6 to the tip shaft portion along the center line of the tip shaft portion. In the range in which the hole is formed, for example, an uneven surface having a maximum height roughness Rz of 5 μm or more and 200 μm or less is formed, and the outer peripheral portion of the tip shaft portion is formed on the inner peripheral surface of the connecting hole. While closely contacting, a part of the outer peripheral portion may be plastically deformed so as to follow the uneven surface, thereby being connected to the cutting head body. In addition, the outer peripheral portion of the distal end shaft portion of the connecting member is closely attached to the inner peripheral portion of the connecting hole as described above, and a part of the outer peripheral portion is fitted into the concave portion, or a part of the outer peripheral portion is set to the uneven surface. In order to cause plastic deformation to follow, the tip shaft portion is inserted into the connecting hole, and a punch (rod-shaped member) having an outer diameter larger than the inner diameter is press-fitted into the hole portion of the connecting member to expand the connecting member. What is necessary is just to carry out plastic deformation so that it may make a diameter.

  The holder 10 to which the cutting head 1 configured as described above is attached is formed of a steel material such as alloy steel that is softer than the cutting edge portion 2 of the cutting head 1 in the present embodiment, and has a substantially cylindrical shape. The inner peripheral portion is a mounting hole 11 into which the rear end portion of the cutting head 1 is inserted. That is, the mounting hole 11 has an inner peripheral surface of the opening on one end side (left side in FIGS. 1 and 2) that is the center line of the mounting hole 11 (the center line of the cylinder formed by the holder 10). A concave conical surface tapered hole 12 whose inner diameter gradually decreases as it goes to the other end side (right side in FIGS. 1 and 2) centering on the line O, and the inner peripheral surface of the tapered hole 12 is The inclination angle formed with respect to the mounting hole center line O is made equal to the inclination angle α. The holder 10 may be formed of a hard material such as a cemented carbide having a hardness equivalent to that of the cutting head 1.

  In addition, in the mounting hole 11, an accommodation hole portion 13 is formed on the other end side of the tapered hole portion 12, and an intermediate member 14 is accommodated in the accommodation hole portion 13. The accommodation hole portion 13 is formed so that one end side thereof has a circular cross section around a mounting hole center line O having a constant inner diameter that is slightly larger than the outer diameter of the screw portion 6 of the cutting head 1. In this embodiment, the end side is formed in an oval cross section as shown in FIG. Here, the ellipse formed by the cross section on the other end side of the accommodation hole portion 13 is a semicircle in which both ends on the major axis side are inscribed in this circle with a smaller radius than the circle formed by one end side of the accommodation hole portion 13. And both ends of these semicircles are connected to each other by a pair of straight lines that are equidistant from the mounting hole center line O and are parallel to each other. A pair of opposed flat surfaces 13A that are parallel to the mounting hole center line O and parallel to each other are disposed in the straight line portion so as to be located at an equal distance from the mounting hole center line O.

  As shown in FIG. 3B, the intermediate member 14 accommodated in the accommodation hole portion 13 is one end portion (FIG. 3B) accommodated in a circular cross-section portion on one end side of the accommodation hole portion 13. 14A is a cylindrical shape having an outer diameter into which the circular section is fitted, and the other end (see FIG. 3 (b) on the right front side) 14B, the one end portion 14A is thus fitted to one end side of the accommodation hole portion 13, and the pair of flat surfaces 13A on the other end side of the accommodation hole portion 13 are thus formed. A pair of flat surfaces 14 </ b> C that can be brought into sliding contact with each other are formed. In this embodiment, the portion between the pair of flat surfaces 14C in the other end portion 14B is connected by an arc surface having a radius substantially equal to the cylindrical surface formed by the outer peripheral surface of the one end portion 14A. The other end portion 14B also has a substantially oval cross section, but a gap is formed on the long axis side of the oval formed by the other end side of the accommodation hole portion 13.

  Accordingly, the one end portion 14A is thus fitted to one end side of the receiving hole portion 13, and the other end portion 14B is brought into sliding contact with the other flat portion 13A, 14C on the other end portion side of the receiving hole portion 13. The intermediate member 14 accommodated in this manner is movable forward and backward in the direction of the mounting hole center line O, and the rotation around the mounting hole center line O is restricted by the contact of the pair of flat surfaces 13A and 14C. It will be. A screw portion (female screw portion) 14D to which the screw portion 6 of the cutting head 1 is screwed is formed on the one end portion 14A so as to be centered on the mounting hole center line O, and the other end portion. 14B is formed with a screw portion (female screw portion) 14E having a diameter smaller than that of the screw portion 14D so as to be centered on the mounting hole center line O. In this embodiment, these screw portions 14D and 14E are They are in communication with each other. The end surface (rear end surface) of the other end portion 14B of the intermediate member 14 is formed to be perpendicular to the mounting hole center line O.

  On the other hand, the attachment hole 11 from the other end surface (rear end surface) of the holder 10 toward the accommodation hole portion 13 is gradually increased as the inner peripheral surface of the other end side opening portion 11A opening to the other end surface is directed to one end side. The conical surface has a concave conical surface centered on the center line O of the mounting hole to be reduced in diameter, and the gap between the opening 11A on the other end side and the accommodation hole 13 is larger than the inner diameter of the screw portion 14E and is an intermediate member. 14 is a small diameter portion 11B having a circular cross section centered on the mounting hole center line O and having a constant inner diameter smaller than the distance between the pair of flat surfaces 14C of the other end portion 14B. Therefore, a stepped surface facing one end side in the mounting hole center line O direction is formed around the portion where the small diameter portion 11B is opened on the other end side of the accommodation hole portion 13, and this stepped surface is attached to the mounting hole portion 13B. It is set to be perpendicular to the hole center line O.

  Further, the mounting bolt 15 is inserted from the other end side of the mounting hole 11 and screwed to the screw portion 14E of the other end portion 14B of the intermediate member 14 accommodated in the accommodation hole portion 13 as described above. That is, the mounting bolt 15 has a threaded portion (male threaded portion) 15A that is screwed into the threaded portion 14E having an outer diameter slightly smaller than the inner diameter of the small-diameter portion 11B. In addition, a head portion 15B is formed on the other end side, and this head portion 15B has an end surface 15C facing the one end side of the mounting hole 11 formed by the other end side opening portion 11A of the mounting hole 11. The concave conical surface and the mounting hole center line O have an equal inclination angle β and a conical surface that gradually decreases in diameter toward one end, and can be brought into close contact with the other end opening 11A. It is said that.

  Here, the inclination angle β formed by the other end side opening portion 11A of the mounting hole 11 having the conical surface shape and the end surface 15C facing the one end side of the head 15B of the mounting bolt 15 with respect to the mounting hole center line O is The taper portion 5 on the outer peripheral surface of the rear end portion of the cutting head 1 and the taper hole portion 12 on the inner peripheral surface of the opening on one end side of the mounting hole 11 are made larger than the inclination angle α formed with respect to the mounting hole center line O. Specifically, it is desirable that the range satisfying α <β is within a range of 20 ° to less than 90 °. In the present embodiment, the range is 30 °. A fitting hole 15D that fits into a work tool such as a hexagon wrench is formed on the end face of the mounting bolt 15 facing the other end of the head 15B.

  In order to perform cutting by attaching the cutting head 1 to the holder 10 in such a head exchangeable cutting tool, first, the intermediate member 14 is inserted into the accommodation hole 13 of the attachment hole 11 in the direction of the attachment hole center line O as described above. The mounting bolt 15 is inserted into the mounting hole 11 from the other end side of the holder 10, and the screw portion 15A is screwed to the screw portion 14E of the intermediate member 14. Thereby, the intermediate member 14 is drawn into the other end side (hole bottom side) of the accommodation hole portion 13, the end surface of the other end portion 14 </ b> B abuts on the stepped surface of the accommodation hole portion 13, and the mounting bolt 15 When the end surface 15C of the head portion 15B is in close contact with the opening 11A on the other end side of the attachment hole 11, it is fixed to the holder 10.

  Therefore, next, the rear end portion of the cutting head 1 is inserted into the mounting hole 11 from one end side of the holder 10, the working tool is engaged with the notch surface 4, and the screw portion 6 is screwed into the one end portion 14 </ b> A of the intermediate member 14. By screwing and screwing into the portion 14D, the taper portion 5 at the rear end portion is brought into close contact with the taper hole portion 12 of the attachment hole 11 and is taper-fitted. The cutting head 1 is fixed to one end of the holder 10 so as to be coaxial with the mounting hole center line O. In the head exchange type cutting tool to which the cutting head 1 is attached in this way, when the holder 10 is held by the machine tool as a shank portion and the cutting edge portion 2 is formed in an end mill shape as in this embodiment, While being rotated around the mounting hole center line O that is coaxial with the axis O, the workpiece is fed in a direction intersecting the mounting hole center line O and the workpiece 3 is cut by the cutting blade 3.

  Then, when the cutting head 1 is replaced, a cutting force or an excessive load more than expected acts on the cutting head 1 during the cutting process, so that the screw portion 6 of the cutting head 1 is strongly screwed into the screw portion 14D of the intermediate member. Due to the difference in thermal expansion coefficient between the cutting head 1 and the holder 10 formed of different materials as described above, the holder 10 is greatly expanded by the cutting heat during the cutting process, and the tapered hole portion 12 is expanded in diameter. As a result, the threaded portion 6 of the cutting head 1 is also screwed into the threaded portion 14D of the intermediate member and further cooled after completion of the cutting, so that the holder 10 is greatly contracted and the tapered portion 5 of the cutting head 1 is attached to the mounting hole 11. Even if it becomes difficult to remove the cutting head 1 due to being tightly tightened in the taper hole portion 12 of the head, the head replacement type cutting tool having the above-described configuration is provided with an intermediate member by the mounting bolt 15. 4 each cutting head 1 can be easily detached extruded into one end of the holder 10.

  That is, while the end face 15C of the head 15B of the mounting bolt 15 is in close contact with the opening 11A on the other end side of the mounting hole 11, the mounting bolt 15 is rotated in a direction in which the screw portion 15A is loosened with respect to the screw portion 14E. Then, since the rotation of the intermediate member 14 is restricted, the intermediate member 14 is pushed and moved toward the opening on the one end side of the mounting hole 11, so that the cutting head 1 is also pushed to the one end side integrally. Since the taper fit is released, the cutting head 1 can be easily removed by loosening the screw portion 6 from the screw portion 14D of the intermediate member 14 in this state.

  Further, when the taper portion 5 of the cutting head 1 is too tightly tightened to the taper hole portion 12 of the mounting hole 11, the end surface 15C of the head portion 15B is in close contact with the other end side opening portion 11A of the mounting hole 11. However, it is difficult to rotate the mounting bolt 15 in the loosening direction with respect to the screw portion 14E, and the head 15B is protruded to the other end side of the holder 10, but at this time, the protrusion 15 is thus protruded. By hitting the head 15B of the mounting bolt 15 to one end side with a plastic hammer or the like, it is possible to release the taper fitting by giving an impact to the cutting head 1 via the intermediate member 14. In this case, the impacted cutting head 1 protrudes to one end side of the holder 10, and the protruding amount is such that the head 15 </ b> B of the mounting bolt 15 is the other end side opening 11 </ b> A of the mounting hole 11. Therefore, it is possible to prevent the cutting head 1 provided with the cutting blade 3 from jumping out too much and hitting a surrounding object or an operator.

  Thus, according to the head exchange type cutting tool having the above-described configuration, even if the cutting head 1 is firmly fixed to the holder 10, it can be easily removed. Therefore, labor and time required for replacing the cutting head 1 can be reduced. Thus, the efficiency of exchanging the cutting head 1 can be improved. Furthermore, even when the cutting head 1 is impacted and removed by a hammer or the like, it is safe without causing any danger to the surroundings.

  Further, in the present embodiment, the end surface 15C facing the one end side of the head 15B of the mounting bolt 15 and the inner peripheral surface of the other end side opening 11A of the mounting hole 11 gradually move toward the one end side of the mounting hole 11. The diameter is reduced to a conical surface with the mounting hole center line O being close to each other as the center. Therefore, when the intermediate member 14 is fixed by the mounting bolt 15, the end surface 15C and the other end opening 11A are fixed. Therefore, the intermediate member 14 and the mounting bolt 15 can be attached to the holder 10 more stably.

  In addition, although the end surface 15C of the head 15B and the other end side opening 11A of the mounting hole 11 have a conical surface shape that can be in close contact with each other, in this embodiment, this conical surface is the mounting hole. The inclination angle β formed with respect to the center line O is the inclination angle formed with respect to the attachment hole center line O of the conical surface formed by the taper portion 5 of the cutting head 1 and the taper hole portion 12 of the one end side opening of the attachment hole 11. Since it is larger than α, the taper fitting between the end face 15C and the other end side opening 11A does not become too strong compared to the taper fitting between the taper part 5 and the taper hole part 12, and is smaller. It is possible to remove the cutting head 1 by rotating the mounting bolt 15 with a force in a direction of loosening from the screw portion 14E of the intermediate member 14.

  In such a case, the inclination angle α formed by the outer peripheral surface of the tapered portion 5 at the rear end portion of the cutting head 11 and the inner peripheral surface of the tapered hole portion 12 at the one end side opening portion of the mounting hole 11 with respect to the mounting hole center line O. Is desirably in the range of 2 ° to 30 ° as in the present embodiment, and when the inclination angle α is less than 2 °, the taper fitting becomes too strong and the cutting head 1 is more difficult to remove. On the contrary, if the inclination angle exceeds 30 °, the taper fitting is insufficient and the cutting head 1 may not be firmly attached to the holder 10.

  The inclination angle β formed by the end surface 15C facing the one end of the head 15B of the mounting bolt 15 and the inner peripheral surface of the other end opening 11A of the mounting hole 11 with respect to the mounting hole center line O is α <β. In addition, it is desirable that the angle is within a range of 20 ° to less than 90 °. When the inclination angle β is less than 20 °, the taper fitting between the end face 15C of the head 15B and the mounting hole 11 is performed. When the cutting head 1 is removed, the mounting bolt 15 may be difficult to rotate when the cutting head 1 is removed. In particular, when the inclination angle β is set to 30 ° as in the present embodiment, the opening 11A on the other end side of the mounting hole 11 has a concave conical surface shape with a full angle of 60 °. In such a case, it can be used also as a center hole fitted to a general center having a convex cone shape with a full angle of 60 °.

  In this embodiment, the mounting hole center line O in which the end surface 15C facing the one end side of the mounting hole 11 in the head 15B of the mounting bolt 15 and the other end side opening 11A of the mounting hole 11 can be in close contact with each other. However, the inclination angle β is 90 °, that is, the end surface 15C and the opening 11A on the other end side are not inclined, and the surface is perpendicular to the center line O of the mounting hole. It may be. In such a case, the end face 15C of the head 15B of the mounting bolt 15 and the opening 11A on the other end side of the mounting hole 11 are not taper-fitted, so the cutting head 1 can be removed with a smaller force. Is possible.

  Further, in the present embodiment, the intermediate member 14 can be moved back and forth in the direction of the mounting hole center line O, and the rotation around the mounting hole center line O is restricted, but the other end portion 14B of the intermediate member 14 and this are accommodated. The other end side of the accommodating hole portion 13 is formed in an oval cross section so that the pair of flat surfaces 13A and 14C are in sliding contact with each other so that the other end portion 14B is fitted, for example, as shown in FIG. As in the modification, the other end portion 14B of the intermediate member 14 is formed in a square cross section around the mounting hole center line O, and the other end side of the accommodation hole portion 13 in which the other end portion 14B is accommodated. The other end portion 14B is formed in a square hole shape that can be fitted, and the four flat surfaces 13A and 14C are in sliding contact with each other, thereby restraining the rotation of the intermediate member 14 and in the direction of the mounting hole center line O. It is good also as advance and retreat freely.

  Further, as in another modification shown in FIG. 5, the other end portion 14B of the intermediate member 14 and the other end side of the accommodation hole portion 13 in which the intermediate member 14 is accommodated are fitted into the one end portion 14A of the intermediate member 14 and this. The housing hole 13 is formed in a circular shape that can be fitted to each other and is coaxial with one end of the receiving hole 13 and has a concave groove 14F extending in the direction of the mounting hole center line O on the outer peripheral surface of the other end 14B. Then, the tip end portion of the pin 16 driven in the direction perpendicular to the mounting hole center line O from the outer peripheral surface of the holder 10 toward the rear end side of the accommodation hole portion 13 is engaged with the concave groove 14F. Thus, the intermediate member 14 may be moved back and forth in the direction of the mounting hole center line O, and the rotation around the mounting hole center line O may be restricted.

  Furthermore, in this embodiment, the screw part 6 of the cutting head 1 and the screw part 15A of the mounting bolt 15 are male screw parts, and the screw parts 14D and 14E of the intermediate member 14 are female screw parts. In particular, the male and female screw portions may be reversed with respect to the screw portion 6 of the cutting head 1 and the screw portion 14D of the intermediate member 14 to which the cutting head 1 is screwed.

DESCRIPTION OF SYMBOLS 1 Cutting head 2 Cutting edge part 5 Tapered part 6 Screw part of cutting head 1 10 Holder 11 Attachment hole 11A The other end side opening part of attachment hole 11 12 Tapered hole part of attachment hole 11 13 Accommodation hole part of attachment hole 11 13A accommodation Flat surface of hole 13 14 Intermediate member 14C Flat surface 14D, 14E of intermediate member 14 Screw portion 15 of intermediate member 14 Mounting bolt 15A Screw portion of mounting bolt 15 15B Head of mounting bolt 15 15C Mounting hole 11 in head 15B The end surface of the cutting head 1 is inclined to the mounting hole center line O with respect to the mounting hole center line O. An inclination angle formed by the end surface 15C of the head portion 15B and the opening 11A on the other end side of the attachment hole 11 with respect to the attachment hole center line O.

Claims (4)

  A cutting head provided with a cutting edge at the front end in the mounting hole formed so as to penetrate the holder has its rear end inserted into the one end side opening of the mounting hole, and is formed at this rear end. A head replaceable cutting tool in which a threaded portion is screwed into an intermediate member housed on the other end side of the one end side opening of the mounting hole and is detachably attached, the rear end of the cutting head The outer peripheral surface of the part and the inner peripheral surface of the opening on one end side of the mounting hole are conical with a mounting hole center line that can be brought into close contact with each other gradually decreasing in diameter toward the other end of the mounting hole. In addition, the intermediate member is movable forward and backward in the direction of the mounting hole center line, and is restricted from rotating around the mounting hole center line. The mounting bolt inserted from the end side is screwed Head exchangeable cutting tool that.   The end face of the head of the mounting bolt facing the one end side of the mounting hole and the inner peripheral surface of the opening of the other end of the mounting hole can be in close contact with each other and gradually reduce in diameter toward the one end side of the mounting hole. The conical surface is centered on the mounting hole center line, and the inclination angle formed by the end surface of the head of the mounting bolt and the inner peripheral surface of the other end opening of the mounting hole with respect to the mounting hole center line is The outer peripheral surface of the rear end portion of the cutting head and the inner peripheral surface of the opening on the one end side of the mounting hole are made larger than an inclination angle formed with respect to the center line of the mounting hole. The described head replaceable cutting tool.   The inclination angle formed by the outer peripheral surface of the rear end portion of the cutting head and the inner peripheral surface of the opening on one end side of the mounting hole is in the range of 2 ° to 30 ° with respect to the mounting hole center line, and the mounting bolt An inclination angle formed by an end surface of the head facing the one end side of the mounting hole and an inner peripheral surface of the opening of the other end of the mounting hole with respect to the mounting hole center line is in a range of 20 ° to less than 90 °. The head replaceable cutting tool according to claim 2, wherein the head replaceable cutting tool is provided.   An end surface facing one end side of the mounting hole in the head of the mounting bolt, and an end surface of the holder in the peripheral edge of the other end opening of the mounting hole facing the end surface are perpendicular to the center line of the mounting hole. The head exchangeable cutting tool according to claim 1, wherein the head exchangeable cutting tool is capable of being in close contact with each other.

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