Interchangeable head cutting tools

Abstract

To provide a head replacement type cutting tool in which fitting positional accuracy of a cutting head to a holde is high.SOLUTION: A head replacement type cutting tool in the present invention comprises a cutting head, a holder to which the cutting head is detachably attached, and a pin member which fixes the cutting head to the holder by thread engagement. The holder is coaxial with a tool rotary shaft, and has a cylindrical part with notch that is elastically deformable in a radial direction perpendicular to the tool rotary shaft. The cutting head is coaxial with the tool rotary shaft, and has: a cutting edge provided at one end in an axial direction; a seating surface provided on the other end side in the axial direction; and a contact part which is located outward in the radial direction of the cylindrical part with notch, and can contact in such a manner that the cylindrical part with notch is elastically deformed outward in the radial direction. An outer diameter of the cylindrical part with notch is larger than a diameter of the contact part of the cutting head.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a cutting tool with an exchangeable head. [Background technology]

[0002] Conventionally, as shown in Patent Document 1 below, for example, a known example of this type of head-exchangeable cutting tool includes a cutting head having a cutting edge on its outer peripheral surface, a holder having an axial tip to which the cutting head is removably attached, and a pin member that secures the cutting head to the holder by screwing it in place.

[0003] For example, the head-exchangeable cutting tool described in Patent Document 1 comprises a cutting head having a cutting edge, a bolt to which the cutting head is detachably attached, and a pin member that fixes the cutting head to the holder by screwing it in place. The holder has a cylindrical portion that is coaxial with the central axis of the holder and is elastically deformable radially outward perpendicular to the central axis. The cutting head has an abutment portion that is arranged radially outward of the cylindrical portion and against which the cylindrical portion can abut. The pin member has a pushing-out portion that abuts against the cylindrical portion from the radially inward direction and elastically deforms the cylindrical portion radially outward. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2012-179685 Summary of the Invention [Problem to be solved by the invention]

[0005] However, conventional cutting tools with replaceable heads have the following problems. In other words, when attaching the cutting head to the holder, the pin member contacts the cylindrical portion from the inside in the radial direction and pushes the cylindrical portion outward in the radial direction while attaching the cutting head. Therefore, depending on the accuracy of the pin member, it may be difficult to push the cylindrical portion out evenly, and the cutting head may not be coaxial with the holder.

[0006] The present invention has been made under the above circumstances, and has as its object to provide a head-exchangeable cutting tool in which the cutting head is attached to the holder with high accuracy in position. [Means for solving the problem]

[0007] In order to achieve the above object, the present invention proposes the following means. That is, the present invention provides a head-exchangeable cutting tool having a tool rotation axis, the cutting head being provided with a cutting head, a holder to which the cutting head is detachably attached, and a pin member that fixes the cutting head to the holder by screwing it into the holder, the holder having a notched cylindrical portion that is coaxial with the tool rotation axis and elastically deformable in a radial direction perpendicular to the tool rotation axis. an insertion hole located inside the notched tubular portion and into which the pin member is inserted; The cutting head has a cutting edge provided at one end in the axial direction, and a seating surface provided at the other end side in the axial direction, Axially penetrating the cutting head, the notched cylindrical portion a through hole having an inner peripheral surface that abuts against the and, The notched tubular portion of the holder is inserted into the through hole of the cutting head, and the notched tubular portion elastically deforms radially inward to reduce its diameter and presses the inner peripheral surface radially outward, thereby positioning the central axis of the cutting head and the central axis of the holder coaxially, and the pin member is inserted into the insertion hole without contacting the notched tubular portion, thereby fixing the cutting head. It is characterized by:

[0008] According to the configuration of the present invention, the outer diameter of the notched tubular portion is larger than the diameter of the abutment portion of the cutting head, so that the notched tubular portion abuts against the abutment portion of the cutting head from the radially inner side and presses the abutment portion of the cutting head so as to spread it outward in the radial direction. As a result of using this alignment mechanism, the accuracy of the attachment position of the cutting head to the holder is improved.

[0009] Furthermore, in one embodiment of the cutting head, the seating surface may have a first uneven portion, an intermediate member may be provided between the cutting head and the holder, the intermediate member may be coaxial with the tool rotation axis, one end of the intermediate member in the axial direction may have a second uneven portion that can fit into the first uneven portion of the cutting head, and the other end of the intermediate member in the axial direction may abut against the holder and be fixed to the holder with a plurality of screws.

[0010] According to the configuration of the present invention, by forming a second concave-convex portion that engages with the first concave-convex portion of the cutting head on an intermediate member separate from the holder, the dimensional accuracy of the notched tubular portion of the holder can be improved. This makes it possible to improve the accuracy of the attachment position of the cutting head relative to the holder. Furthermore, the degree of freedom in shaping the first concave-convex portion and the second concave-convex portion can be increased.

[0011] In addition, in one embodiment of the cutting head of the present invention, the tool diameter of the head-exchangeable cutting tool may be φ10 mm or more and φ25 mm or less, and the cutting head may be manufactured from cemented carbide and may be configured to have a plurality of the cutting edges.

[0012] According to the configuration of the present invention, by using cemented carbide only for the cutting head, the cost of the tool can be reduced. Also, since the cutting head and the mounting screws are not too small compared to the tool diameter, the burden on the worker involved in attaching and detaching the cutting head can be reduced. [Effects of the Invention]

[0013] According to the present invention, it is possible to provide a head-exchangeable cutting tool in which the cutting head is attached to the holder with high accuracy in position. [Brief explanation of the drawings]

[0014] [Figure 1] FIG. 1 is an assembly drawing (perspective view) showing the configuration of a cutting tool with an exchangeable head according to one embodiment of the present invention. [Figure 2]FIG. 2 is an assembly diagram (side view) showing the configuration of a cutting tool with an exchangeable head according to one embodiment of the present invention. [Figure 3] FIG. 3 is a plan view of the holder as seen from the tip side. [Figure 4] FIG. 4 is a side view showing the configuration of the holder. [Figure 5] FIG. 5 is a perspective view showing a state in which an intermediate member is attached to the tip end side of the holder with a screw. [Figure 6] FIG. 6 is a plan view of the intermediate member 6 as seen from the tip end side. [Figure 7] FIG. 7 is a side view seen from the direction indicated by arrow VII in FIG. [Figure 8] FIG. 8 is a side view seen from the direction indicated by arrow VIII in FIG. [Figure 9] FIG. 9 is a plan view showing a state in which the intermediate member is attached to the tip end side of the holder with a screw. [Figure 10] FIG. 10 is a side view showing a state in which the intermediate member is attached to the tip side of the holder. [Figure 11] FIG. 11 is a plan view showing the configuration of the head-exchangeable cutting tool as viewed from the cutting head side. [Figure 12] FIG. 12 is a side view showing the configuration of a cutting tool with an exchangeable head. [Figure 13] FIG. 13 is a plan view showing the configuration of the cutting head as viewed from the rear end side. [Figure 14] FIG. 14 is a perspective view showing the configuration of the cutting head as viewed from the rear end side. [Figure 15] FIG. 15 is a perspective view showing each cut of the cutting head. [Figure 16] FIG. 16 is a graph showing the amount of deflection in the example and the comparative example. DETAILED DESCRIPTION OF THE INVENTION

[0015] <Replaceable head cutting tool> Hereinafter, a head-exchangeable cutting tool 1 according to one embodiment of the present invention will be described with reference to FIGS. Fig. 1 is an assembly view (perspective view) showing the configuration of an exchangeable head cutting tool 1 according to one embodiment of the present invention. Fig. 2 is an assembly view (side view) showing the configuration of an exchangeable head cutting tool 1 according to one embodiment of the present invention. Fig. 3 is a plan view of a holder 3 as seen from the tip side. Fig. 4 is a side view showing the configuration of the holder 3.

[0016] The head-exchangeable cutting tool 1 of this embodiment is an end mill with an exchangeable head. In the following description, the side of the cutting head 2 along the axial direction of the tool rotation axis O of the exchangeable head cutting tool 1 is referred to as the leading end side, and the side opposite the cutting head 2 is referred to as the trailing end side. In addition, the direction perpendicular to the tool rotation axis O of the exchangeable head cutting tool 1 is referred to as the radial direction, and the direction revolving around the tool rotation axis O is referred to as the circumferential direction.

[0017] 1 and 2, the head-exchangeable cutting tool 1 includes a cutting head 2 having a cutting edge, a holder 3 to which the cutting head 2 is detachably attached, and a pin member 4 that secures the cutting head 2 to the holder 3 by threaded engagement. In this embodiment, the cutting tool further includes an intermediate member 6 disposed between the holder 3 and the cutting head 2, and a plurality of screws 7 for securing the intermediate member 6 to the holder 3.

[0018] The head-exchangeable cutting tool 1 is a tool that can rotate around a tool rotation axis O, and has a cutting head 2 attached to the tip of a holder 3, and the rear end of the holder 3 is gripped by the spindle of a machine tool, and is rotated in a tool rotation direction T around the tool rotation axis O while being fed in a direction intersecting the tool rotation axis O, thereby performing cutting on a workpiece with multiple cutting edges 2A provided on the cutting head 2.

[0019] (holder) 3 and 4, the holder 3 is made of a metal material such as steel and is formed into a cylindrical shape centered on the tool rotation axis O (central axis C3). The cross section of the holder 3 perpendicular to the tool rotation axis O is circular. The holder 3 is integrally formed with a holder main body 3B and a tip tube portion (notched tube portion) 3A provided at the tip of the holder main body 3B.

[0020] The holder body 3B has a first female threaded hole 3d that opens at the radial center of a tip end surface 3b facing the tip end and extends from the tip end surface 3b toward the base end along the tool rotation axis O (center axis C3). An internal thread is formed on the inner peripheral surface of the first female threaded hole 3d. The first female threaded hole 3d is formed so as to be able to threadably engage with the male thread portion 4A of the pin member 4 shown in Figures 1 and 2.

[0021] Furthermore, two second female threaded holes 3e protrude from the holder body 3B on both radially outer sides of the first female threaded hole 3d. An internal thread is formed on the inner peripheral surface of each second female threaded hole 3e. The lengths of the two second female threaded holes 3e along the tool rotation axis O are equal to each other and shorter than the first female threaded hole 3d. The diameters of the second female threaded holes 3e are equal to each other and smaller than the first female threaded hole 3d. Each of these second female threaded holes 3e is formed so that the screw 7 shown in FIGS. 1 and 2 can be threaded therein.

[0022] 3 and 4, the tip tube portion 3A has an outer diameter smaller than that of the holder main body 3B. In addition, the tip tube portion 3A has an outer diameter larger than the diameter of a hole (2d3) on the base end side of the through hole 2D of the cutting head 2, which will be described later.

[0023] The tip tube portion 3A has a cylindrical shape that protrudes from the tip surface 3b toward the tip side, and is coaxial with the tool rotation axis O. The tip tube portion 3A has a plurality of dividing wall portions 3a that are formed so as to be divided along the circumferential direction around the tool rotation axis O.

[0024] The divided wall portions 3a are formed at positions spaced apart from each other by equal distances in the radial direction from the tool rotation axis O. An insertion hole 3g is formed inside each of the divided wall portions 3a (tip tube portion 3A) so that the male thread portion 4A of the pin member 4 can be inserted therein. The insertion hole 3g has a diameter larger than that of the male thread portion 4A of the pin member 4.

[0025] In this embodiment, for example, four partition walls 3a are provided, but the number of partition walls 3a is not limited to four.

[0026] As shown in FIG. 3, the partition walls 3a are spaced apart from one another in the circumferential direction around the tool rotation axis O. Each partition wall 3a has an arc-shaped cross section perpendicular to the tool rotation axis O. By arranging the partition walls 3a in the circumferential direction around the tool rotation axis O, the tip tube portion 3A has an overall cylindrical shape, as shown in FIG. 4. The outer peripheral surface of the tip end of each partition wall 3a is machined into an R-shape. In this embodiment, the cutting head 2 is replaced for use, so machining the outer peripheral surface of the tip end of each partition wall 3a into an R-shape enables smooth attachment and detachment of the cutting head 2 to and from the holder 3. In addition, uneven damage to the tip tube portion 3A and the partition walls 3a is suppressed, and good attachment position accuracy of the cutting head 2 to the holder 3 can be maintained for a long period of time.

[0027] (Intermediate parts) Fig. 5 is a perspective view showing a state in which the intermediate member 6 is attached to the tip side of the holder 3. Fig. 6 is a plan view of the intermediate member 6 as seen from the tip side. Fig. 7 is a side view as seen from the direction indicated by arrow VII in Fig. 6. Fig. 8 is a side view as seen from the direction indicated by arrow VIII in Fig. 6.

[0028] As shown in Fig. 5, the intermediate member 6 is coaxial with the tool rotation axis O and is attached to the tip side of the holder 3 as shown in Fig. 5. The intermediate member 6 is made of a metal material such as steel and is formed into a disk shape centered on the central axis C6 as shown in Figs. 6, 7, and 8. The outer diameter of the intermediate member 6 is approximately equal to the outer diameter of the holder main body 3B of the holder 3 (Fig. 11).

[0029] The intermediate member 6 has a through hole 6a that penetrates the thickness direction at the radial center coaxially with the central axis C6, and a pair of through holes 6b that are provided parallel to the through hole 6a on both radially outer sides of the through hole 6a. The through hole 6a is a hole through which the tip tube portion 3A of the holder 3 shown in Figures 1 and 2 is inserted. The diameter of the through hole 6a is slightly larger than the maximum outer diameter of the tip tube portion 3A of the holder 3. The pair of through holes 6b are holes through which the screws 7 shown in Figure 5 are inserted.

[0030] As shown in Figures 5 to 8, a pair of convex portions (second concave-convex portions) 6A facing each other in the radial direction are formed on the tip side of the intermediate member 6. As shown in Figures 5, 6 and 8, the pair of convex portions 6A are formed radially outward from the through hole 6a at positions facing each other in a direction perpendicular to the radial direction in which the pair of through holes 6b are aligned in a plan view. The pair of convex portions 6A are formed on the outer peripheral surface side, radially outwardly separated from the through hole 6a.

[0031] The pair of convex portions 6A are protrusions that are fan-shaped when viewed from the axial direction and are formed so that they can be accommodated in recesses (first concave-convex portions) 2B (FIGS. 1, 2, and 11) formed in the cutting head 2, which will be described later. The pair of convex portions 6A have the same shape and size. The inner wall surface 6d of each convex portion 6A facing the through hole 6a (center axis C6) is inclined with respect to the center axis C6. Specifically, the inner wall surface 6d is inclined radially outward as it approaches the axial tip. Each tip surface 6e facing the axial tip is located on a plane perpendicular to the center axis C6.

[0032] 6, each of the pair of protrusions 6A has a side surface 6f that is inclined at a certain angle toward the protrusion 6A with respect to the tool rotation direction T and extends in a radial direction perpendicular to the central axis C6. The side surface 6f is inclined in a direction that inclines toward the protrusion 6A as it approaches the axial tip.

[0033] On the other hand, the side surface 6g of the protrusion 6A facing the opposite side to the tool rotation direction T is inclined at a certain angle toward the protrusion 6A with respect to the tool rotation direction T and extends in a direction along the radial direction perpendicular to the central axis C6. The side surface 6g is inclined in a direction approaching the side surface 6f as it approaches the axial tip side. As a result, each of the protrusions 6A is formed so as to become wider in the circumferential direction toward the radially outer periphery side relative to the central axis C6 and toward the rear end side in the axial direction.

[0034] The intermediate member 6 has a pair of flat surfaces 6h perpendicular to the axial direction between the protrusions 6A that face each other in the radial direction via the through holes 6a and the through holes 6a. These pair of flat surfaces 6h serve as abutment surfaces against which the rear end surface of the cutting head 2 (described later) abuts. The outer peripheral edge 6i of the flat surfaces 6h is located on a circumference centered on the central axis C6. The outer peripheral surfaces 6j of the pair of protrusions 6A that face radially outward are formed as cylindrical surfaces that are flush with the outer peripheral surface of the holder 3.

[0035] As shown in Fig. 6, a groove 6B is formed in the center of the tip end of the intermediate member 6. The groove 6B extends in a direction perpendicular to the central axis C6 and the direction in which the pair of protrusions 6A oppose each other when viewed from the axial direction. The groove 6B has a width 6W that is smaller than the diameter 6D of the through hole 6a. The bottom surface 6k of the groove 6B is perpendicular to the axial direction and parallel to the flat surface 6h.

[0036] The intermediate member 6 has a base end surface 6n on the axial rear side thereof that is perpendicular to the axial direction and parallel to the flat surface 6h and the bottom surface 6k. The base end surface 6n of the intermediate member 6 is a surface that abuts against the tip surface 3b of the holder 3.

[0037] Fig. 9 is a plan view showing a state in which the intermediate member 6 is screwed to the tip side of the holder 3. Fig. 11 is a side view showing a state in which the intermediate member 6 is attached to the tip side of the holder 3. 9 and 10, when the intermediate member 6 is attached to the tip side of the holder 3, the tip tube portion 3A of the holder 3 is inserted into the central through-hole 6a, and the base end surface 6n is brought into contact with the tip surface 3b of the holder 3. As shown in Fig. 9, a screw 7 is inserted into the through-hole 6b (Fig. 6) of the intermediate member 6 arranged on the tip side of the holder 3, and the screw is tightened while being screwed into the second female screw hole 3e (Fig. 3) on the holder 3 side, thereby fixing the intermediate member 6 to the holder 3.

[0038] As shown in FIG. 10, when the intermediate member 6 is attached to the tip side of the holder 3, the leading end side of the tip tube portion 3A of the holder 3 protrudes further toward the axial tip side than the protrusion 6A of the intermediate member 6.

[0039] The pair of screws 7 are made of steel and each have a cylindrical male thread portion 7A and a head portion 7B having a larger diameter than the male thread portion 7A, as shown in Fig. 1. The male thread portion 7A is subjected to male thread processing (not shown) so as to screw into the second female thread hole 3e of the holder 3.

[0040] The pair of screws 7 are inserted into through holes 6b formed in the intermediate member 6, and their male threaded portions 7A are screwed into second female threaded holes 3e formed in the holder 3. The heads 7B of the screws 7 are respectively housed in the grooves 6B of the intermediate member 6.

[0041] If the holder 3 and the intermediate member 6 were molded integrally, there is a risk that a cutting tool (such as a small-diameter end mill) used to form a notch in the tip tube portion 3A during tool manufacturing may interfere with the protrusion 6A. In particular, in a small-diameter tool having a diameter φ of 25 mm or less as in this embodiment, the smaller the tool diameter, the more limited the space available for providing the protrusion 6A on the holder 3. On the other hand, in this embodiment, the convex portion 6A and the tip tube portion 3A are formed separately, so there is no need to consider the manufacturing difficulties described above, and therefore the degree of freedom in design increases.

[0042] (Cutting head) Fig. 11 is a plan view showing the configuration of the head-exchangeable cutting tool 1 as seen from the cutting head 2 side. Fig. 12 is a side view showing the configuration of the head-exchangeable cutting tool 1. Fig. 13 is a plan view showing the configuration of the cutting head 2 as seen from the rear end side. Fig. 14 is a perspective view showing the configuration of the cutting head 2 as seen from the base end surface 2C side.

[0043] As shown in FIGS. 11 and 12, the cutting head 2 is disposed on the tip side of the holder 3 via an intermediate member 6, and is fixed to the holder 3 by a pin member 4. 11, the cutting head 2 is formed in a disk shape centered on the tool rotation axis O and made of cemented carbide or the like having a higher hardness than the holder 3. The cutting head 2 has a tip surface 2a facing the tip side in the axial direction, multiple cutting edges 2A, a base end surface (seat surface) 2C facing the rear end side in the axial direction, a pair of recesses 2B opening in the base end surface 2C, and a through hole 2D penetrating in the thickness direction along the central axis C2.

[0044] The cutting edges 2A are formed on an outer peripheral surface 2b that faces radially outward and is adjacent to a tip surface 2a that faces the axial tip side and is perpendicular to the central axis C2. In this embodiment, six cutting edges 2A1, 2A2, 2A3, 2A4, 2A5, and 2A6 are provided around the central axis C2.

[0045] The outer diameter of the cutting head 2 is slightly larger than the outer diameter of the holder 3 (see FIG. 12). Here, the central axis C2 of the cutting head 2 is coaxial with the central axis C3 of the holder 3 when the cutting head 2 is attached to the holder 3, and therefore these central axes C2 and C3 in the head-exchangeable cutting tool 1 are common axes and coaxial with the tool rotation axis O.

[0046] 1, 13, and 14, through hole 2D formed in the center of cutting head 2 has a multi-stage shape consisting of a plurality of holes 2d1 (FIG. 1), 2d2 (FIGS. 13 and 14), and 2d3 (FIGS. 13 and 14) with different diameters. Of the plurality of holes 2d1, 2d2, and 2d3 aligned in the direction from the tip side along the central axis C2, the inner diameter of central hole 2d2 is the smallest, and the inner diameters of tip-side hole 2d1 and rear-side hole 2d3 are larger than hole 2d2 and are the same.

[0047] As shown in Figure 12, when the cutting head 2 is attached to the tip of the holder 3, the tip tube portion 3A of the holder 3 is inserted into the through hole 2D of the cutting head 2. At this time, the tip tube portion 3A of the holder 3 is inserted into the hole 2d3 from the base end (base end surface 2C) side of the through hole 2D of the cutting head 2. The hole 2d3 of the through hole 2D is cylindrical, corresponding to the tip tube portion 3A, and has a diameter D2 (Figure 14) slightly smaller than the outer diameter D3 (Figure 4) of the tip tube portion 3A of the holder 3.

[0048] When the cutting head 2 is attached to the tip of the holder 3, the tip tube portion 3A, which has an outer diameter larger than the diameter of a hole 2d3 located on the base end side of the through hole 2D, is inserted into the through hole 2D of the cutting head 2. At this time, when the tip tube portion 3A is inserted into the hole 2d3, each divided wall portion 3a of the tip tube portion 3A elastically deforms radially inward, and the outer peripheral surfaces of each divided wall portion 3a abut against the inner peripheral surface of the hole (abutment portion) 2d3 of the through hole 2D of the cutting head 2. In other words, the inner peripheral surface of the hole 2d3 on the base end side of the through hole 2D of the cutting head 2 is the abutment portion with which the outer peripheral surface of the tip tube portion 3A (each divided wall portion 3a) of the holder 3 can abut.

[0049] A hole 2d2 located at the center of the through hole 2D in the axial direction is a hole into which the male thread portion 4A of the pin member 4 is inserted, and has a diameter slightly larger than the outer diameter of the male thread portion 4A.

[0050] Furthermore, a hole 2d1 located on the axial tip side of the through hole 2D is a hole in which the head 4B of the pin member 4 is housed, and has a diameter slightly larger than the outer diameter of the head 4B (FIG. 1).

[0051] A plurality of recesses 2B are formed on the base end surface 2C of the cutting head 2. The recesses 2B are open to the base end surface 2C and recessed toward the tip side in the axial direction. In this embodiment, a pair of recesses 2B is formed on both radial sides of the through hole 2D. The pair of recesses 2B is formed on the outer peripheral surface side, spaced radially outward from the through hole 2D. The pair of recesses 2B is a hole into which the pair of protrusions 6A of the intermediate member 6 is inserted, and has a fan shape when viewed from the axial direction.

[0052] As shown in Figure 12, when the cutting head 2 is attached to the tip of the holder 3 via the intermediate member 6, a pair of recesses 2B formed on the base end surface 2C of the cutting head 2 and a pair of protrusions 6A formed on the tip of the intermediate member 6 abut against and engage with each other.

[0053] As described above, this head-exchangeable cutting tool 1 restricts relative rotation around the tool rotation axis O with respect to the holder 3 (intermediate member 6) by engaging a pair of protrusions 6A of the intermediate member 6 with a pair of recesses 2B of the cutting head 2, respectively. In this way, a rotation regulating portion 11 having a recess 2B and a protrusion 6A that engage with each other is formed on the base end side of the cutting head 2 and the tip end side of the intermediate member 6 that faces the base end side of the cutting head 2.

[0054] The pin member 4 is made of steel. The pin member 4 has a cylindrical male threaded portion 4A and a head portion 4B having a larger diameter than the male threaded portion 4A. The male threaded portion 4A is externally threaded (not shown) so as to be threaded into the first female threaded hole 3d of the holder 3. The outer diameter of the male threaded portion 4A is smaller than the minimum diameter (hole 2d2) of the through hole 2D of the cutting head 2. As a result, when the pin member 4 is inserted inside the tip tube portion 3A, the pin member 4 is threaded into the first female threaded hole 3d of the holder 3 without coming into contact with the tip tube portion 3A (dividing wall portion 3a).

[0055] In this manner, when the male thread portion 4A of the pin member 4 is threaded into the first female thread hole 3d of the holder 3, it is coaxial with the central axis C3 of the holder 3, and these central axes C4, C3 are a common axis. Also, as described above, the central axis C3 of the holder 3 and the central axis C2 of the cutting head 2 are a common axis, and therefore these central axes C2, C3, C4 are a common axis (coaxial) and are also coaxial with the tool rotation axis O.

[0056] Next, the aligning mechanism of the head-exchangeable cutting tool 1 of this embodiment configured as described above and its effect (improvement of the mounting position accuracy of the cutting head 2 relative to the holder 3) will be described. In this embodiment, the "alignment mechanism" refers to the shape and function for coaxially positioning the tool rotation axis O with the central axis C2 of the cutting head 2 and the central axis C3 of the holder 3 when attaching the cutting head 2 to the holder 3.

[0057] 1 and 2, when the intermediate member 6 is placed on the tip side of the holder 3, the tip tube portion 3A of the holder 3 is inserted into the through hole 6a formed in the center of the intermediate member 6, and the base end surface 6n of the intermediate member 6 comes into contact with the tip surface 3b of the holder 3. In this state, the intermediate member 6 is fixed to the holder 3 with a pair of screws 7.

[0058] Next, with the intermediate member 6 fixed to the tip end of the holder 3, the cutting head 2 is placed on the tip end of the intermediate member 6 and the cutting head 2 is pushed in so that the tip end tubular portion 3A of the holder 3 protruding from the intermediate member 6 is inserted into the hole 2d3 on the base end side of the through-hole 2D of the cutting head 2. As a result, the inner circumferential surface of the hole 2d3 of the cutting head 2 elastically deforms each of the divided wall portions 3a of the tip end tubular portion 3A radially inward evenly, thereby reducing the diameter of the tip end tubular portion 3A. The restoring force of each divided wall portion 3a elastically deformed radially inward contacts the inner circumferential surface of the hole 2d3 of the cutting head 2 and uniformly presses the inner circumferential surface radially outward. As a result, the cutting head 2 is clamped to the holder 3. As a result, the central axis C2 of the cutting head 2 is positioned coaxially with the central axis C3 of the holder 3.

[0059] Then, the base end surface 2C of the cutting head 2 and the flat surface 6h of the intermediate member 6 come into contact with each other, and the pair of convex portions 6A of the intermediate member 6 and the pair of concave portions 2B of the cutting head 2 engage with each other so as to mesh with each other.

[0060] From this state, the pin member 4 is inserted into the insertion hole 3g of the tip tube portion 3A of the holder 3 through the through hole 2D of the cutting head 2. The diameter of the male thread portion 4A of the pin member 4 is smaller than the diameter of the insertion hole 3g formed inside the tip tube portion 3A of the holder 3. Therefore, the pin member 4 is screwed into the first female thread hole 3d of the holder 3 without coming into contact with the tip tube portion 3A (each divided wall portion 3a). In this way, the cutting head 2 is fixed to the holder 3 by screwing and tightening the male threaded portion 4A of the pin member 4 into the first female threaded hole 3d formed in the center of the holder 3. In this state, the central axis C3 of the holder 3, the central axis C6 of the intermediate member 6, the central axis C2 of the cutting head 2, and the central axis C4 of the pin member 4 are coaxial with one another.

[0061] On the other hand, when replacing the cutting head 2 that has been used for cutting with another new cutting head 2, the pin member 4 is removed from the holder 3 by reversing the above-described procedure. As a result, the tip tube portion 3A is restored and deformed, and is separated from the hole 2d3 of the through hole 2D of the cutting head 2.

[0062] As described above, according to the head-exchangeable cutting tool 1 of this embodiment, by pushing the tip tube portion 3A of the holder 3 into the hole 2d3 on the base end side of the through hole 2D of the cutting head 2 and moving the cutting head 2 closer to the holder 3, each divided wall portion 3a of the tip tube portion 3A is elastically deformed uniformly radially inward by the inner surface (abutment portion) of the through hole 2D (hole 2d3) of the cutting head 2, and at the same time, the elastic restoring force of each divided wall portion 3a causes the outer surface of each divided wall portion 3a to abut against the inner surface of the hole 2d3 of the through hole 2D and press the inner surface radially outward. In this way, the cutting head 2 is fixed to the holder 3, and the holder 3 and the cutting head 2 are positioned coaxially.

[0063] As a result, in the head-exchangeable cutting tool 1 of this embodiment, unlike an alignment mechanism using the pin member 4, the holder 3 and the cutting head 2 can be attached with high precision using only the holder 3 and the cutting head 2. Furthermore, the pin member 4 is inserted without contacting the tip tube portion 3A, making the attachment work easy.

[0064] In this embodiment, an intermediate member 6 is interposed between the holder 3 and the cutting head 2. By providing the intermediate member 6, which is separate from the holder 3, with a convex portion 6A that fits into the concave portion 2B of the cutting head 2, the dimensional accuracy of the tip tube portion 3A can be improved, and as a result, it is possible to improve the accuracy of the attachment position of the cutting head 2 to the holder 3. Furthermore, the fit between the concave portion 2B and the convex portion 6A provides an anti-rotation effect for the cutting head 2, and also allows for greater freedom in shaping the concave portion 2B and the convex portion 6A.

[0065] The maximum outer diameter (tool diameter) of the replaceable head cutting tool 1 in this embodiment is φ10 mm or more and φ25 mm or less. Generally, solid tools are used when the tool diameter is φ16 mm or less, and indexable cutting tools are often used when the tool diameter is φ16 mm or more. That is, the tool diameter in this embodiment is in the range from the large diameter side of solid tools to the small diameter side of indexable cutting tools.

[0066] In this embodiment, the cutting head 2 can be accurately positioned relative to the holder 3 by the tip tube portion 3A of the holder 3, thereby achieving machining accuracy close to that of a solid tool. By using cemented carbide only for the cutting head 2 and manufacturing the holder 3 and intermediate member 6 from steel, it is possible to keep the price of the entire cutting tool down and manufacture it more cheaply than a solid tool.

[0067] Furthermore, in configurations where the tool diameter is small and multiple cutting inserts are provided, the cutting inserts themselves are small in size, and therefore the mounting screws are also small, which means that attaching and detaching the cutting inserts takes time and places a heavy burden on the worker. However, in this embodiment, even if the tool diameter is small as in conventional cases, the cutting head and mounting screws are larger than the cutting inserts and mounting screws, so attaching and detaching the cutting head is easy and the burden on the worker is reduced.

[0068] As described above, according to this embodiment, it is possible to further improve the accuracy of the attachment position of the cutting head 2 to the holder 3 without complicating the manufacturing process.

[0069] The present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention.

[0070] For example, in the above-described embodiment, the tip tube portion 3A has a cylindrical shape as a whole, and the through-hole 2D (hole 2d3) of the cutting head 2 has a corresponding cylindrical hole shape, but this is not limited to this. That is, the tip tube portion 3A may have a non-circular cross section, such as a polygonal or elliptical cylindrical shape, and the through-hole 2D of the cutting head 2 may have a non-circular cross section corresponding to the shape of the tip tube portion 5, such as a polygonal or elliptical cylindrical hole shape. In this case, the tip tube portion 3A and the through hole 2D not only improve the mounting position accuracy as described above, but also restrict the relative rotation between the cutting head 2 and the holder 3.

[0071] Furthermore, in the above-described embodiment, the head-exchangeable cutting tool 1 is an end mill with an exchangeable head, but is not limited to this and may be, for example, a threading tool (tap) with an exchangeable head or the like. Furthermore, although the cutting edge 2A of the cutting head 2 is formed on the tip surface 2a and the outer peripheral surface 2b, the cutting edge 2A may be formed on either the tip surface 2a or the outer peripheral surface 2b. [Example]

[0072] The effects of the present invention will be confirmed below. The radial runout of a tool is an important indicator of mounting accuracy. If the radial runout of a tool is large, it directly leads to deterioration in machining dimensional accuracy and machined surface quality, and variation in tool life. Therefore, with the cutting head 2 attached to the holder 3, the radial runout of the tool was measured for all cutting edges 2A1 to 2A6 of the cutting head 2 using a commercially available dial gauge. The side surface of the holder 3 was used as the reference during measurement. Note that in the following paragraphs and Table 1, radial runout will simply be referred to as "runout."

[0073] In the embodiment, the holder 3 has a tip tube portion 3A, and an intermediate member 6 is provided between the holder 3 and the cutting head 2. In the comparative example, the holder 3 does not have the tip tube portion 3A, and the intermediate member 6 is not provided between the holder 3 and the cutting head 2. FIG. 15 is a perspective view showing each cutting edge 2A1 to 2A6 of the cutting head 2. Table 1 shows the measurement results for each cutting edge shown in FIG. 15. Here, the maximum runout in Table 1 refers to the difference between the minimum and maximum runout amounts. FIG. 16 is a graph showing the runout amounts of each cutting edge 2A1 to 2A6 in the example and comparative example corresponding to the cutting edge position on the cutting head 2 for the results in Table 1. In FIG. 16, the example is shown by a solid line and the comparative example is shown by a dashed line. The values ​​(0, 10, 20, 30, 40, 50, 60) shown in FIG. 16 indicate the runout amounts, and are expressed in μm.

[0074] [Table 1]

[0075] As shown in Table 1, in the case of the configuration of the present invention, the maximum runout of each of the cutting edges 2A1 to 2A6 was 18 μm. On the other hand, in the case of the comparative example, the maximum runout of each of the cutting edges 2A1 to 2A6 was 60 μm. Therefore, it was confirmed that the mounting position accuracy when the cutting head 2 using the aligning mechanism of the present invention was mounted on the holder 3 was better than that of the comparative example.

[0076] While the preferred embodiments of the present invention have been described above with reference to the accompanying drawings, it goes without saying that the present invention is not limited to these examples. It is clear that a person skilled in the art can conceive of various modifications or alterations within the scope of the technical ideas described in the claims, and it is understood that these also naturally fall within the technical scope of the present invention. The configurations of the respective embodiments may be combined as appropriate. [Industrial Applicability]

[0077] According to the present invention, it is possible to provide a head-exchangeable cutting tool 1 in which the cutting head 2 is attached to the holder 3 with high accuracy in position. [Explanation of symbols]

[0078] 1...Replaceable head cutting tool 2...Cutting head 2C...Base end surface (seating surface) 2A,2A1…blade 2B...Concave portion (first concave / convex portion) 3...Holder 3A...Tip tube part (tube part with notch) 4...Pin member 6...Intermediate member 6A...Convex portion (second concave-convex portion) 6D,D2…Diameter 7...Screw 2d3…hole (contact part) D3: Outer diameter O...Tool rotation axis

Claims

1. A head-exchangeable cutting tool having a tool rotation axis, A cutting head; a holder to which the cutting head is detachably attached; a pin member that fixes the cutting head to the holder by screwing it into the holder; the holder has a notched tubular portion that is coaxial with the tool rotation shaft and elastically deformable in a radial direction perpendicular to the tool rotation shaft, and an insertion hole that is located inside the notched tubular portion and into which the pin member is inserted, The cutting head A cutting edge provided at one end in the axial direction; a seating surface provided on the other end side in the axial direction; a through hole that passes through the cutting head in the axial direction and has an inner circumferential surface that abuts against the notched cylindrical portion, the notched cylindrical portion of the holder is inserted into the through hole of the cutting head, and the notched cylindrical portion is elastically deformed inward in the tool radial direction to reduce its diameter and presses the inner circumferential surface outward in the radial direction, thereby positioning the central axis of the cutting head and the central axis of the holder coaxially; The pin member is inserted into the insertion hole without contacting the notched cylindrical portion, and fixes the cutting head. Cutting tool with replaceable head.

2. the cutting head has a first uneven portion on the seating surface, an intermediate member is provided between the cutting head and the holder; the intermediate member is coaxial with the tool rotation shaft, a second concave-convex portion at one end of the axial direction that can be fitted with the first concave-convex portion of the cutting head; the other end in the axial direction abuts against the holder and is fixed to the holder with a plurality of screws; The head-exchangeable cutting tool according to claim 1 .

3. The tool diameter of the head-exchangeable cutting tool is φ10 mm or more and φ25 mm or less, The cutting tool according to claim 1 or 2, wherein the cutting head is made of cemented carbide and includes a plurality of the cutting edges.

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