Indexable cutting tools

Abstract

To precisely align a cutting insert, to stably clamp it, to suppress the positional deviation of the cutting insert to a tip end side in an axial direction at clamping, and to improve versatility.SOLUTION: A holder 3 has a holder cylinder portion 32 that has a male screw portion 32a on an outer peripheral surface, and a regulating portion 34 that regulates rotations about a center axis C and movement toward a rear end side in an axial direction of the cutting insert 2. The cutting insert 2 has a columnar portion 24, and a locking portion 25 contacted with the regulating portion 34. A chuck mechanism 4 has an installation cylinder portion 41 that has a female screw portion 41a on an inner peripheral surface, and a collet portion 42 capable of changing a diameter. A holder cylinder portion 32 has an inner peripheral tapered surface 32b. The collet portion 42 has an outer peripheral tapered surface 42b slidably contacted with the inner peripheral tapered surface 32b. The installation cylinder portion 41 has a forcing portion 41b that can force the collet portion 42 to the rear end side in the axial direction when the screwing amount of the male screw portion 32a and the female screw portion 41a is increased.SELECTED DRAWING: Figure 5

Description

[Technical field]

[0001] The present invention relates to an indexable cutting tool. [Background technology]

[0002] Known examples of conventional indexable cutting tools include those described in the following Patent Documents 1 to 4. The indexable cutting tool includes an axially extending cutting insert centered on a central axis, a columnar holder extending in the axial direction and having an insertion hole into which the cutting insert is inserted, and a fixing mechanism for removably fixing the cutting insert inserted into the insertion hole to the holder.

[0003] Specifically, in Patent Document 1, the insert is fixed to the holder by abutting the inclined surface at the rear end of the insert against a positioning member provided in the insertion hole of the holder, and then abutting the tip flat surface of the screw member that screws into the holder against a second cut surface on the top surface of the insert.

[0004] In addition, in Patent Document 2, the cutting insert is fixed to the holder via a retaining ring by screwing a threaded nut into the threaded sleeve with the inclined surface at the rear end of the cutting insert in contact with a lateral stop in the insertion hole of the holder.

[0005] Also, in Patent Document 3, with the rear end face of the throw-away tip (cutting insert) in contact with a fixed member in the insertion hole of the holder, a bolt is screwed into the holder to connect the first slit grooves of the holder, whereby the wall surface of the hole is pressed against the holder restraint portion of the tip, and the side of the tip is restrained by the holder.

[0006] In addition, in Patent Document 4, when the chamfered area of ​​the cutting insert abuts against the positioning pin in the insertion hole of the holder, a wrench is used to tighten the union nut to the clamp chuck, causing the clamp chuck to contract in diameter and clamp the cutting insert. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] JP 2013-71214 A [Patent Document 2] German Patent No. 19831743 [Patent Document 3] Patent No. 3690675 [Patent Document 4] U.S. Patent No. 9,993,880 Summary of the Invention [Problem to be solved by the invention]

[0008] Conventional indexable cutting tools have the following problems. In Patent Document 1, the insert is pressed against a part of the inner peripheral surface of the insertion hole of the holder by pressing the upper surface of the insert with a screw member, so that the insert comes into contact with the insertion hole on one side, causing the core (center axis) of the holder and the insert to be misaligned and reducing durability. In addition, when the screw member is tightened, the insert may be misaligned toward the tip side in the axial direction relative to the holder.

[0009] In Patent Document 2, the cutting insert cannot be stably fixed in the radial direction to the insertion hole of the holder, and there is a risk of misalignment between the holder and the cutting insert. Also, there is a risk of the cutting insert being misaligned toward the tip side in the axial direction relative to the holder.

[0010] In Patent Document 3, the side surface of the throw-away tip is sandwiched and clamped by the wall surface of the hole, so the clamping force and rigidity of the tip cannot be secured in a radial direction other than the sandwiching direction. Also, there is a risk that the throw-away tip may be misaligned toward the tip side in the axial direction relative to the holder.

[0011] In Patent Document 4, there is a risk that the cutting insert may be misaligned toward the tip side in the axial direction relative to the holder. Moreover, in Patent Documents 1 to 4, only one type of cutting insert diameter can be used for one type of holder, which reduces versatility.

[0012] One of the objects of the present invention is to provide an indexable cutting tool that can accurately align a cutting insert with respect to a holder, can stably clamp the cutting insert, can prevent the cutting insert from shifting axially toward the tip side when clamped, and can enable the use of multiple types of cutting inserts with different diameters with one type of holder, thereby increasing versatility. [Means for solving the problem]

[0013] One aspect of the indexable cutting tool of the present invention includes a shaft-shaped cutting insert extending in an axial direction about a central axis, a columnar holder having an insertion hole into which the cutting insert is inserted and extending in the axial direction, and a chuck mechanism for removably fixing the cutting insert inserted in the insertion hole to the holder, the holder including a holder tubular portion located at a tip end of the holder in the axial direction, arranged coaxially with the insertion hole, and having a male thread portion on an outer peripheral surface, a restricting portion that contacts the cutting insert inside the insertion hole and restricts rotation of the cutting insert about the central axis and movement of the cutting insert toward a rear end side in the axial direction, and a restricting portion that opens into the outer peripheral surface of the holder and the insertion hole, A radial direction perpendicular to the central axis and a female screw hole located toward the tip end in the axial direction as the regulating portion extends inwardly of the insertion hole, the regulating portion being a male screw member screwed into the female screw hole and protruding into the insertion hole, the cutting insert having a columnar portion at least a portion of which is disposed inside the holder tubular portion, a locking portion contacting the regulating portion, and a cutting edge protruding toward the tip end in the axial direction beyond the holder tubular portion, the chuck mechanism comprising: a mounting tubular portion having a female screw portion on an inner peripheral surface thereof screwed into the male screw portion; and a cutting edge separate from the mounting tubular portion, Said radial directiona cylindrical collet portion having a variable diameter and disposed between the mounting tubular portion, the holder tubular portion, and the columnar portion, wherein the holder tubular portion has an inner peripheral tapered surface whose inner diameter increases toward the tip side in the axial direction, the collet portion has an outer peripheral tapered surface whose outer diameter increases toward the tip side in the axial direction and which is in slidable contact with the inner peripheral tapered surface, and the mounting tubular portion has a push-in portion that is capable of pushing the collet portion toward the rear end side in the axial direction when the amount of screwing of the male screw portion and the female screw portion is increased. 。

[0014] In the indexable cutting tool of the present invention, a cutting insert is inserted into the radially inner side of the cylindrical collet portion, and with the engagement portion of the cutting insert in contact with the regulating portion within the insertion hole of the holder, the mounting cylindrical portion is screwed into the holder cylindrical portion, whereby the cutting insert is clamped while being aligned with the holder and fixed to the holder.

[0015] Specifically, the locking portion of the cutting insert is brought into contact with the restricting portion of the holder, so that the rotation of the cutting insert around the central axis and the movement of the cutting insert toward the rear end side in the axial direction relative to the holder are restricted. That is, the cutting insert is aligned in the circumferential direction and positioned in the axial direction (toward the rear end side). From this state, when the mounting tube is rotated around the central axis to increase the amount of screwing between the female thread and the male thread, the pushing portion of the mounting tube pushes the collet toward the rear end in the axial direction. As a result, the outer tapered surface of the collet and the inner tapered surface of the holder tube slide against each other, causing the collet to contract in diameter, and the inner surface of the collet to press the cylindrical portion of the cutting insert from the outside in the radial direction. In other words, the collet applies a pulling force to the cutting insert toward the rear end in the axial direction, clamping the cutting insert evenly in the circumferential direction.

[0016] According to the present invention, the insertion hole and the holder cylindrical portion are coaxial with each other, and the cutting insert is clamped by the collet portion which is reduced in diameter by sliding contact with the holder cylindrical portion, so that the cutting insert can be precisely aligned coaxially with the insertion hole of the holder.

[0017] In addition, there is no need to provide a D-cut flat surface or the like on the cylindrical portion of the cutting insert for contacting the tip of the screw member as in the conventional method, and the present invention increases the rigidity of the cutting insert. Also, a large contact area can be secured between the outer peripheral surface of the cylindrical portion and the inner peripheral surface of the collet portion, i.e., the collet portion can hold the cutting insert over the entire circumference around the central axis, so that the cutting insert can be stably clamped. And, according to the present invention, the tool rigidity is secured uniformly in the circumferential direction.

[0018] In addition, when the collet portion clamps the cutting insert, the collet portion applies a pulling force to the cutting insert toward the other axial side, so that the state in which the locking portion of the cutting insert abuts against the regulating portion of the holder is well maintained. Therefore, the cutting insert is prevented from shifting in position toward the tip side in the axial direction during clamping. In other words, in the present invention, the axial positioning accuracy of the cutting insert is stably ensured before and after clamping. In addition, it is also possible to screw the mounting tube into the holder tube when the locking portion of the cutting insert and the regulating portion of the holder are arranged close to each other with a gap between them, and use the retracting force of the collet to move the cutting insert toward the rear end in the axial direction so that the locking portion and the regulating portion come into contact with each other. In this case, the positioning accuracy of the cutting insert is ensured, and operability when clamping the insert is further improved.

[0019] In addition, by replacing the collet part, which is separate from the mounting tube part, with another collet part having a different inner diameter, it is possible to use multiple types of cutting inserts with different diameters for one type of holder. Therefore, the indexable cutting tool of the present invention can be adapted to various cutting conditions, etc., and has high versatility.

[0020] In addition, in the present invention, the cutting insert can be clamped at the tip of the tool by, for example, rotating the mounting tube from the front of the holder, which provides good operability. In addition, since the cutting insert is firmly clamped at the tip of the tool, the tool rigidity is increased, chatter vibration during cutting can be suppressed, and machining accuracy is stably improved. In the above-mentioned indexable cutting tool, the holder has a female threaded hole that opens to the outer peripheral surface of the holder and the insertion hole and is positioned toward the tip side in the axial direction as it extends radially inward, and the regulating portion is a male threaded member that is screwed into the female threaded hole and protrudes into the insertion hole. In this case, by adjusting the amount of screwing of the male screw member into the female screw hole, the axial position where the locking portion of the cutting insert and the male screw member (regulating portion) come into contact can be finely adjusted, thereby making it possible to finely adjust the axial position of the cutting edge of the cutting insert, i.e., the amount of protrusion.

[0021] In the above-mentioned indexable cutting tool, it is preferable that the collet portion has a plurality of slits spaced apart from one another in the circumferential direction around the central axis, and that the diameter of the collet portion changes as the width of the slits decreases or increases.

[0022] In this case, the diameter of the collet portion can be reduced or expanded with a simple configuration, and the cutting insert can be stably clamped evenly in the circumferential direction by the collet portion.

[0023] In the above-mentioned indexable cutting tool, it is preferable that the collet portion is arranged on the outer peripheral surface of the collet portion and has a receiving portion shaped like a tapered surface that increases in diameter toward the rear end in the axial direction, and the push-in portion is arranged on the inner peripheral surface of the mounting tube portion and has a tapered surface shaped like a tapered surface that increases in diameter toward the rear end in the axial direction, and that the receiving portion can be pushed toward the rear end in the axial direction.

[0024] In this case, even if the collet portion is pressed into the holder tubular portion and the diameter of the collet portion is reduced, the contact state between the tapered receiving portion and the tapered pushing portion is maintained well, so that the pushing portion can stably push the receiving portion toward the rear end in the axial direction, and the cutting insert can be stably clamped.

[0025] In the above-mentioned indexable cutting tool, it is preferable that the locking portion is provided on the cutting insert at a plurality of positions spaced apart from each other in the axial direction.

[0026] In this case, by appropriately selecting one of the locking parts to be brought into contact with the restricting part of the holder, the protruding amount of the cutting edge of the cutting insert can be appropriately selected. In other words, it is easy to greatly change the protruding amount of the cutting edge by using one cutting insert.

[0033] In the above-described indexable cutting tool, it is preferable that the chuck mechanism has a bearing interposed between the push-in portion and the collet portion.

[0034] In this case, even if the mounting tube portion is rotated around the central axis when the cutting insert is clamped, the bearing provided between the push-in portion and the collet portion prevents the collet portion from rotating with the mounting tube portion. In other words, since the collet portion is prevented from rotating, only a pressing force (clamping force) from the radial outside and a pulling force toward the axial rear end side can be applied to the cutting insert via the collet portion. This allows the cutting insert to be precisely aligned in the circumferential direction and positioned in the axial direction, and reduces the load on each positioning element (such as the restricting portion and the locking portion).

[0035] In the above-mentioned indexable cutting tool, the cutting insert may have an axial insert shank extending in the axial direction and a blade portion arranged at the axial tip of the insert shank, the cutting edge being arranged on the blade portion, and the cylindrical portion and the locking portion being arranged on the insert shank.

[0036] In this case, for example, the insert shank can be made of a material that is tougher and less expensive than the cutting edge, thereby reducing tool costs and further preventing damage to the locking portion and the like. Effect of the Invention

[0037] According to one embodiment of the indexable cutting tool of the present invention, the cutting insert can be precisely aligned with the holder, the cutting insert can be stably clamped, and the cutting insert can be prevented from shifting axially toward the tip side when clamped. In addition, multiple types of cutting inserts each having a different diameter can be used with one type of holder, thereby enhancing versatility. [Brief description of the drawings]

[0038] [Figure 1] FIG. 1 is a perspective view showing an indexable cutting tool according to the present embodiment. [Diagram 2] FIG. 2 is a side view showing the indexable cutting tool of the present embodiment. [Diagram 3] FIG. 3 is a top view showing the indexable cutting tool of the present embodiment. [Figure 4] FIG. 4 is a front view showing the indexable cutting tool of the present embodiment. [Diagram 5] FIG. 5 is a cross-sectional view showing the indexable cutting tool of the present embodiment. [Figure 6] FIG. 6 is a cross-sectional view showing a first modified example of the indexable cutting tool of the present embodiment. [Figure 7] FIG. 7 is a cross-sectional view showing a second modified example of the indexable cutting tool of the present embodiment. [Figure 8] FIG. 8 is a cross-sectional view showing a third modified example of the indexable cutting tool of the present embodiment. [Figure 9] FIG. 9 is a cross-sectional view showing a fourth modified example of the indexable cutting tool of the present embodiment. [Figure 10] FIG. 10 is a top view showing a part of an indexable cutting tool according to a fifth modified example of the present embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0039] An indexable cutting tool 1A according to one embodiment of the present invention will be described with reference to the drawings. 1 to 5, an indexable cutting tool 1A of this embodiment is an indexable cutting tool used in turning, and is detachably mounted on a tool rest or the like of a machine tool M such as an NC lathe. Specifically, this indexable cutting tool 1A is used for finishing the inner peripheral surface of a pilot hole pre-drilled in a workpiece (not shown).

[0040] As shown in Figure 5, the indexable cutting tool 1A includes an axial cutting insert 2 centered on a central axis C, a cylindrical holder 3 having an insertion hole 31 into which the cutting insert 2 is inserted, and a chuck mechanism 4 that removably fixes the cutting insert 2 inserted into the insertion hole 31 to the holder 3. The cutting insert 2, the holder 3 and the chuck mechanism 4 are arranged coaxially with each other with a central axis C as a common axis.

[0041] [Direction definition] In this embodiment, the direction in which the central axis C extends is referred to as the axial direction. The cutting insert 2 has a portion that protrudes from the holder 3 in the axial direction. In this embodiment, in the axial direction, the direction in which the cutting insert 2 protrudes from the holder 3 is referred to as the leading end side, and the opposite direction is referred to as the trailing end side. Moreover, a direction perpendicular to the central axis C is called a radial direction. In the radial direction, a direction approaching the central axis C is called a radially inner direction, and a direction away from the central axis C is called a radially outer direction. The cutting insert 2 has a rake face 21, which will be described later, at the tip end in the axial direction. In this embodiment, in the radial direction, the direction to which the rake face 21 faces is called an upper side, and the opposite direction is called a lower side. Note that the upper side and the lower side are names simply used to explain the relative positional relationship of each part, and the actual positional relationship, etc. may be a positional relationship, etc. other than the positional relationship, etc. indicated by these names. Moreover, the direction going around the central axis C is called the circumferential direction.

[0042] [Cutting insert] The cutting insert 2 is made of, for example, cemented carbide, and in this embodiment, is integrally formed from a single member. The cutting insert 2 extends in the axial direction. At least the tip of the cutting insert 2 protrudes from the holder 3 toward the tip side. The cutting insert 2 has a rake face 21, a clearance face 22, a cutting edge 23, a cylindrical portion 24, and a locking portion 25.

[0043] 1 to 4, the rake face 21, the flank 22 and the cutting edge 23 are disposed at the tip portion of the cutting insert 2. The rake face 21, the flank 22 and the cutting edge 23 protrude toward the tip side in the axial direction beyond a holder tubular portion 32 (described later) of the holder 3. The rake face 21, the flank 22 and the cutting edge 23 are located toward the tip side of the holder 3 and the chuck mechanism 4 in the axial direction.

[0044] The rake face 21 is flat and faces radially upward. The flank face 22 has a portion (front flank face) facing the tip side in the axial direction and a portion (side flank face) facing radially outward. The cutting edge 23 is located at a ridge portion where the rake face 21 and the flank face 22 are connected. In this embodiment, the cutting edge 23 is substantially V-shaped in the top view shown in FIG. 3. The cutting edge 23 protrudes toward the tip side in the axial direction and radially outward beyond the portion of the tip portion of the cutting insert 2 other than the cutting edge 23.

[0045] As shown in FIG. 5, the cylindrical portion 24 is cylindrical about the central axis C and extends in the axial direction. The cylindrical portion 24 is disposed in an intermediate portion between both axial ends of the cutting insert 2. Although not particularly shown, the cylindrical portion 24 has a circular cross section perpendicular to the central axis C. In other words, the outer peripheral surface of the cylindrical portion 24 is cylindrical about the central axis C. At least a portion of the cylindrical portion 24 is disposed inside a holder tubular portion 32 of the holder 3, which will be described later. Specifically, the cylindrical portion 24 is disposed throughout the inside of the insertion hole 31, the inside of the holder tubular portion 32, and the inside of the chuck mechanism 4.

[0046] The locking portion 25 is disposed at the rear end of the cutting insert 2. In this embodiment, the locking portion 25 has an inclined surface shape that is inclined with respect to the central axis C. In the illustrated example, the locking portion 25 is positioned upward toward the tip side in the axial direction. The locking portion 25 has a planar shape that expands in a direction intersecting the central axis C, and in this embodiment, has a substantially elliptical shape. The locking portion 25 is disposed over substantially the entire rear end face of the cutting insert 2, and includes a portion located on the central axis C. The locking portion 25 comes into contact with a regulating portion 34 of the holder 3, which will be described later.

[0047] [Holder] The constituent members of the holder 3 are made of, for example, steel. The holder 3 extends in the axial direction about a central axis C. As shown in Fig. 5, when the indexable cutting tool 1A is attached to a machine tool M, the portion of the holder 3 other than its tip is embedded in the machine tool M. The holder 3 has an insertion hole 31, a holder cylindrical portion 32, a female screw hole 33, and a restricting portion 34.

[0048] The insertion hole 31 penetrates the holder 3 in the axial direction. The central axis of the insertion hole 31 is arranged coaxially with the central axis C of the holder 3. The axial tip portion 31a of the insertion hole 31 opens into the inside of the holder tubular portion 32. The axial rear end portion 31b of the insertion hole 31 opens to the rear end surface of the holder 3. The inner diameter of the intermediate portion 31c located between the tip portion 31a and the rear end portion 31b in the axial direction of the insertion hole 31 is larger than the inner diameter of the tip portion 31a and smaller than the inner diameter of the rear end portion 31b. The axial length of the intermediate portion 31c is larger than the axial length of the tip portion 31a and larger than the axial length of the rear end portion 31b. In this embodiment, the cutting insert 2 is inserted into the tip portion 31a of the insertion hole 31 and the tip side portion of the intermediate portion 31c. The cylindrical portion 24 of the cutting insert 2 is slidably inserted (fitted) into the tip portion 31a.

[0049] The holder tubular portion 32 is located at the axial tip of the holder 3. The central axis of the holder tubular portion 32 is arranged coaxially with the central axis C of the insertion hole 31. When the indexable cutting tool 1A is attached to the machine tool M, the holder tubular portion 32 is exposed to the outside without being embedded inside the machine tool M. In this embodiment, the outer diameter of the holder tubular portion 32 other than the rear end portion is smaller than the outer diameter of the rear end portion. The holder tubular portion 32 has a male thread portion 32a and an inner peripheral tapered surface 32b.

[0050] The male thread portion 32a is provided on the outer circumferential surface of the holder tubular portion 32. In this embodiment, the male thread portion 32a is disposed in a portion of the holder tubular portion 32 other than the rear end portion. The inner peripheral tapered surface 32b is disposed on the inner peripheral surface of the holder cylindrical portion 32. The inner peripheral tapered surface 32b is tapered such that the inner diameter increases toward the tip side in the axial direction.

[0051] The female screw hole 33 opens into the outer peripheral surface of the holder 3 and the insertion hole 31, and is located toward the axial tip side as it moves radially inward. The female screw hole 33 extends in a direction intersecting (inclined) with the central axis C. The female screw hole 33 is a circular hole and has a female screw on its inner peripheral surface. In this embodiment, the female screw hole 33 opens into an intermediate portion of the outer peripheral surface of the holder 3 that is located between both axial ends, and into an intermediate portion 31c of the inner peripheral surface of the insertion hole 31.

[0052] The restricting portion 34 contacts the cutting insert 2 inside the insertion hole 31 and restricts the rotation of the cutting insert 2 around the central axis C (i.e., the circumferential direction) and the movement toward the rear end side in the axial direction. In this embodiment, the restricting portion 34 is a male screw member 34a that is screwed into the female screw hole 33 and protrudes into the insertion hole 31. The male screw member 34a is, for example, a set screw. The male screw member 34a is cylindrical and has a male screw on its outer circumferential surface. The tip surface of the male screw member 34a contacts the locking portion 25 of the cutting insert 2 from the rear end side in the axial direction and from the outside in the radial direction. In this embodiment, the tip surface of the male screw member 34a is flat and comes into surface contact with the locking portion 25. 1 and 3, the female screw hole 33 and the male screw member 34a (the restricting portion 34) are omitted.

[0053] [Chuck mechanism] The constituent members of the chuck mechanism 4 are made of, for example, steel, etc. As shown in FIGS.

[0054] The mounting cylinder portion 41 has a cylindrical shape centered on a central axis C. The mounting cylinder portion 41 has a female thread portion 41a, a push-in portion 41b, a rib portion 41c, and a locking surface 41d. The female screw portion 41a is disposed at the axial rear end portion of the inner circumferential surface of the mounting tube portion 41. The female screw portion 41a is screwed into the male screw portion 32a of the holder tube portion 32.

[0055] The push-in portion 41b is disposed at the axial tip of the inner circumferential surface of the mounting tube portion 41. When the mounting tube portion 41 is rotated about the central axis C to increase the amount of screwing between the male screw portion 32a and the female screw portion 41a, the push-in portion 41b can push the collet portion 42 toward the axial rear end. In this embodiment, the push-in portion 41b has a tapered surface shape that increases in diameter toward the axial rear end, and can push a receiving portion 42c (described later) of the collet portion 42 toward the axial rear end.

[0056] The rib portion 41c is disposed in a portion of the inner circumferential surface of the mounting tube portion 41 that is located between the female thread portion 41a and the push-in portion 41b in the axial direction. The rib portion 41c is annular about the central axis C, protrudes radially inward from the inner circumferential surface of the mounting tube portion 41, and extends in the circumferential direction.

[0057] A plurality of locking surfaces 41d are provided at intervals from one another in the circumferential direction on the outer circumferential surface of the mounting tube portion 41. The locking surfaces 41d are planar and parallel to the central axis C, and face radially outward. A working tool such as a wrench (not shown) can be locked to the locking surfaces 41d.

[0058] As shown in FIG. 5, the collet portion 42 is separate from the mounting tube portion 41, that is, is composed of a separate member from the mounting tube portion 41. The collet portion 42 is cylindrical about the central axis C and extends in the axial direction. The cutting insert 2 is inserted into the collet portion 42. The cutting insert 2 protrudes from the collet portion 42 on both sides in the axial direction, that is, on the front end side and the rear end side. The collet portion 42 is disposed between the mounting tube portion 41 and the holder tube portion 32 and the cylindrical portion 24 of the cutting insert 2 in the radial direction. The outer peripheral surface of the collet portion 42 contacts the inner peripheral surfaces of the mounting tube portion 41 and the holder tube portion 32, and the inner peripheral surface of the collet portion 42 contacts the outer peripheral surface of the cylindrical portion 24.

[0059] The collet portion 42 is variable in diameter, that is, it can be contracted and expanded. The collet portion 42 can move in the axial direction relative to the mounting tube portion 41 and the holder tube portion 32 by changing the diameter. Specifically, as shown in FIG. 4, the collet portion 42 has a plurality of slits 42a arranged at intervals in the circumferential direction, and the diameter of the collet portion 42 changes by decreasing or increasing the width of the slits 42a. In this embodiment, as shown in FIG. 4, the plurality of slits 42a are arranged radially around the central axis C as viewed from the axial direction. Although not particularly shown, in a state in which the cutting insert 2 is not inserted inside the collet portion 42, the collet portion 42 can be taken out from inside the mounting tube portion 41 to the outside by contracting the collet portion 42. That is, the collet portion 42 is detachable from the mounting tube portion 41, and can be replaced with another collet portion 42 having a different inner diameter, for example.

[0060] As shown in FIG. 5, the collet portion 42 has an outer circumferential tapered surface 42b, a receiving portion 42c, and a groove portion 42d. The outer peripheral tapered surface 42b is disposed on the outer peripheral surface of the collet portion 42. In this embodiment, the outer peripheral tapered surface 42b is disposed on a portion of the outer peripheral surface of the collet portion 42 other than the axial tip. The outer peripheral tapered surface 42b is tapered such that the outer diameter increases toward the axial tip. The outer peripheral tapered surface 42b comes into slidable contact with the inner peripheral tapered surface 32b of the holder tube portion 32.

[0061] The receiving portion 42c is disposed on the outer peripheral surface of the collet portion 42. In this embodiment, the receiving portion 42c is disposed at the axial tip of the outer peripheral surface of the collet portion 42. The receiving portion 42c has a tapered surface shape that increases in diameter toward the rear end side in the axial direction. The receiving portion 42c comes into slidable contact with the push-in portion 41b of the mounting tube portion 41.

[0062] 5, in a vertical cross-sectional view along the central axis C, the direction in which the receiving portion 42c inclines with respect to the central axis C is different from the direction in which the outer peripheral tapered surface 42b inclines with respect to the central axis C. In this embodiment, the inclination angle of the receiving portion 42c with respect to the central axis C is larger than the inclination angle of the outer peripheral tapered surface 42b with respect to the central axis C. In addition, the axial length of the outer peripheral tapered surface 42b is longer than the axial length of the receiving portion 42c.

[0063] Groove portion 42d is disposed in a portion of the outer circumferential surface of collet portion 42 that is located between outer circumferential tapered surface 42b and receiving portion 42c in the axial direction. Groove portion 42d is annular about central axis C, recessed radially inward from the outer circumferential surface of collet portion 42, and extends circumferentially. Rib portion 41c of mounting tube portion 41 is inserted into groove portion 42d. Rib portion 41c is movable within a predetermined range in the axial direction and in the circumferential direction inside groove portion 42d.

[0064] [Effects of this embodiment] In the replaceable-tip cutting tool 1A of this embodiment described above, the cutting insert 2 is inserted into the radially inner side of the cylindrical collet portion 42, and the mounting cylindrical portion 41 is screwed into the holder cylindrical portion 32 with the locking portion 25 of the cutting insert 2 in contact with the male thread member 34a (regulating portion 34) within the insertion hole 31 of the holder 3, whereby the cutting insert 2 is clamped while being aligned with the holder 3 and fixed to the holder 3.

[0065] Specifically, the locking portion 25 of the cutting insert 2 is brought into contact with the restricting portion 34 of the holder 3, thereby restricting the rotation of the cutting insert 2 about the central axis C and the movement of the cutting insert 2 toward the rear end side in the axial direction relative to the holder 3. That is, the cutting insert 2 is aligned in the circumferential direction and positioned in the axial direction (toward the rear end side). From this state, when the mounting tube portion 41 is rotated around the central axis C to increase the amount of screwing between the female screw portion 41a and the male screw portion 32a, the pushing portion 41b of the mounting tube portion 41 pushes the collet portion 42 toward the rear end side in the axial direction. As a result, the outer peripheral tapered surface 42b of the collet portion 42 and the inner peripheral tapered surface 32b of the holder tube portion 32 come into sliding contact with each other, causing the collet portion 42 to contract in diameter, and the inner peripheral surface of the collet portion 42 presses the columnar portion 24 of the cutting insert 2 from the radial outside. That is, the collet portion 42 clamps the cutting insert 2 evenly in the circumferential direction while exerting a pulling force on the cutting insert 2 toward the rear end side in the axial direction.

[0066] According to this embodiment, the insertion hole 31 and the holder cylindrical portion 32 are coaxial with each other, and the cutting insert 2 is clamped by the collet portion 42 whose diameter is reduced by sliding contact with the holder cylindrical portion 32, so that the cutting insert 2 can be precisely aligned coaxially with the insertion hole 31 of the holder 3.

[0067] Moreover, unlike the conventional method, it is not necessary to provide the cylindrical portion 24 of the cutting insert 2 with a D-cut flat portion or the like for contacting the tip of the screw member, and according to this embodiment, the rigidity of the cutting insert 2 is increased. Also, a large contact area between the outer peripheral surface of the cylindrical portion 24 and the inner peripheral surface of the collet portion 42 can be ensured, that is, the collet portion 42 can hold the cutting insert 2 over the entire circumference around the central axis C, so that the cutting insert 2 can be stably clamped. And according to this embodiment, the tool rigidity is ensured uniformly in the circumferential direction.

[0068] Furthermore, when the collet portion 42 clamps the cutting insert 2, the collet portion 42 applies a pulling force to the cutting insert 2 toward the other axial side, so that the locking portion 25 of the cutting insert 2 is well maintained in abutment against the restricting portion 34 of the holder 3. This prevents the cutting insert 2 from being displaced toward the tip side in the axial direction during clamping. That is, in this embodiment, the axial positioning accuracy of the cutting insert 2 is stably ensured before and after clamping. It is also possible to screw the mounting tube portion 41 into the holder tube portion 32 from a state in which the locking portion 25 of the cutting insert 2 and the regulating portion 34 of the holder 3 are disposed close to each other with a gap therebetween, and use the pulling force of the collet portion 42 to move the cutting insert 2 toward the rear end side in the axial direction, thereby bringing the locking portion 25 into contact with the regulating portion 34. In this case, the positioning accuracy of the cutting insert 2 is ensured, and operability during insert clamping is further improved.

[0069] Furthermore, by replacing the collet portion 42, which is separate from the mounting tube portion 41, with another collet portion 42 having a different inner diameter, it is possible to use a plurality of types of cutting inserts 2 having different diameters with one type of holder 3. Therefore, the indexable cutting tool 1A of the present embodiment can accommodate various cutting conditions, etc., and has high versatility.

[0070] In this embodiment, the cutting insert 2 can be clamped at the tip of the tool exposed from the machine tool M, for example, by rotating the mounting tube 41 from the front of the holder, providing good operability. In addition, since the cutting insert 2 is firmly clamped at the tip of the tool, the tool rigidity is increased, chatter vibration during cutting can be suppressed, and machining accuracy is stably improved.

[0071] In this embodiment, the collet portion 42 has a plurality of slits 42a, and the diameter of the collet portion 42 changes as the width of these slits 42a decreases or increases. In this case, the diameter of the collet portion 42 can be reduced or expanded with a simple configuration. The collet portion 42 can stably clamp the cutting insert 2 evenly in the circumferential direction.

[0072] In this embodiment, collet portion 42 has receiving portion 42c having a tapered surface, mounting tube portion 41 has pushing portion 41b having a tapered surface, and pushing portion 41b is capable of pushing receiving portion 42c toward the rear end side in the axial direction. In this case, even if the collet portion 42 is reduced in diameter by being pressed into the holder tubular portion 32, the contact state between the tapered surface-shaped receiving portion 42c and the tapered surface-shaped pushing portion 41b is well maintained. Therefore, the pushing portion 41b can stably push the receiving portion 42c toward the rear end side in the axial direction, and the cutting insert 2 can be stably clamped.

[0073] In this embodiment, the holder 3 has a female screw hole 33, and the restricting portion 34 is a male screw member 34a that is screwed into the female screw hole 33 and protrudes into the insertion hole 31. In this case, the axial position where the locking portion 25 of the cutting insert 2 and the male screw member 34a (regulating portion 34) come into contact with each other can be finely adjusted by adjusting the amount of screwing of the male screw member 34a into the female screw hole 33. This allows fine adjustment of the axial position of the cutting edge 23 of the cutting insert 2, i.e., the amount of protrusion. Although not particularly shown, the holder 3 may have another screw member (fixing screw) that can come into contact with the outer circumferential surface of the male screw member 34a, etc. In this case, by fixing the male screw member 34a with the other screw member, the protruding amount of the cutting blade 23 that is finely adjusted by the screwing amount of the male screw member 34a can be well maintained.

[0074] [Other configurations included in the present invention] The present invention is not limited to the above-described embodiment, and the configuration may be modified within the scope of the present invention, for example as described below.

[0075] 6 to 9 show first to fourth modified examples of the indexable cutting tool 1A described in the above embodiment. In the drawings of each modified example, the same components as those in the above embodiment are denoted by the same reference numerals, and the following mainly describes the differences.

[0076] FIG. 6 shows an indexable cutting tool 1B of a first modified example. In this modified example, a plurality of locking portions 25 are provided on the cutting insert 2 at intervals in the axial direction. The locking portions 25 are disposed on the outer periphery of the rear end portion of the cutting insert 2. Of the plurality of locking portions 25, the locking portion 25 located furthest rearward in the axial direction is provided so as to cut out a portion of the rear end surface of the cutting insert 2. Each locking portion 25 is a substantially semicircular flat surface. The male screw member 34a (regulating portion 34) comes into contact (surface contact) with one of the plurality of locking portions 25. According to the first modified example, by appropriately selecting one of the multiple locking portions 25 to be brought into contact with the restricting portion 34 of the holder 3, it is possible to appropriately select the protruding amount of the cutting edge 23 of the cutting insert 2. In other words, it is easy to greatly change the protruding amount of the cutting edge 23 by using one cutting insert 2.

[0077] FIG. 7 shows a second modified example of an indexable cutting tool 1C. In this modified example, the holder 3 has a pin hole 35 that opens to the outer circumferential surface of the holder 3 and the insertion hole 31, and the regulating portion 34 is a pin member 34b that fits into the pin hole 35 and passes through the inside of the insertion hole 31. The pin hole 35 penetrates the holder 3 along a virtual plane (not shown) perpendicular to the central axis C. The pin hole 35 is a circular hole. In the illustrated example, the central axis of the pin hole 35 and the central axis C of the holder 3 are arranged in a twisted position. The pin member 34b is cylindrical and is inserted into the pin hole 35. In the insertion hole 31, the pin member 34b contacts the locking portion 25 of the cutting insert 2 from the rear end side in the axial direction and from the outside in the radial direction. In this modified example, a part of the outer circumferential surface of the pin member 34b makes line contact with the locking portion 25. According to the second modified example, the pin member 34b (the restricting portion 34) is prevented from moving axially relative to the holder 3, so that the accuracy of the axial position of the cutting edge 23 of the cutting insert 2, that is, the amount of protrusion, is stably ensured.

[0078] FIG. 8 shows a third modified example of an indexable cutting tool 1D. In this modified example, the locking portion 25 is disposed on the rear end surface of the cutting insert 2. The locking portion 25 is V-shaped and opens to the rear end side when viewed from the radial direction as shown in FIG. 8. The locking portion 25 has a pair of semicircular flat surfaces, and the pair of flat surfaces are connected to each other so as to form an obtuse angle on the central axis C. In this modified example, the central axis of the pin hole 35 extends in a direction perpendicular to the central axis C of the holder 3, that is, in the radial direction. The pin member 34b that fits into the pin hole 35 makes line contact with the pair of flat surfaces of the locking portion 25 at two points on its outer circumferential surface, that is, at a portion located above the central axis C and a portion located below the central axis C. According to the third modified example, the pin member 34b (regulating portion 34) is prevented from moving axially relative to the holder 3, so that the accuracy of the axial position of the cutting edge 23 of the cutting insert 2, i.e., the amount of protrusion, is stably ensured. Furthermore, when the cutting insert 2 is clamped, the force of the pin member 34b supporting the locking portion 25 acts on the lower and upper sides, so that the accuracy of centering of the cutting insert 2 is more stable. Note that when the locking portion 25 is disposed on the rear end surface of the cutting insert 2 as in the second and third modified examples, the rigidity of the cutting insert 2 is easily increased.

[0079] FIG. 9 shows a cutting tool 1E of a fourth modified example. In this modified example, a plurality of locking portions 25 are provided on the cutting insert 2 at intervals in the axial direction. The pin member 34b (regulating portion 34) comes into contact (line contact) with one of the plurality of locking portions 25. The cutting insert 2 also has an abutment portion 26 that comes into contact with the pin member 34b from the rear end side in the axial direction. The abutment portions 26 are provided on the cutting insert 2 at intervals in the axial direction. The abutment portions 26 are disposed on the outer periphery of the rear end portion of the cutting insert 2. Each abutment portion 26 is a substantially semicircular flat surface. The pin member 34b comes into contact (line contact) with one of the plurality of abutment portions 26. According to the fourth modified example, the movement of the cutting insert 2 toward the rear end side and the tip end side in the axial direction is restricted by the contact between the locking portion 25 and the pin member 34b (the restricting portion 34) and the contact between the abutting portion 26 and the pin member 34b. For example, even if a force acts to pull the cutting insert 2 out of the insertion hole 31 of the holder 3 toward the tip end side in the axial direction during cutting, the cutting insert 2 is prevented from coming out.

[0080] In the above-described embodiment and each modified example, the receiving portion 42c of the collet portion 42 is in direct contact with the pushing portion 41b of the mounting tube portion 41 so as to be freely slidable therewith, but the present invention is not limited to this. Although not particularly shown, the chuck mechanism 4 may have a bearing interposed between the pushing portion 41b and the collet portion 42 (the receiving portion 42c). The bearing is, for example, a rolling bearing such as a tapered ball bearing centered on the central axis C. The bearing may also be a tapered cylindrical dry bearing or the like. In this case, even if the mounting tube portion 41 is rotated around the central axis C when the cutting insert 2 is clamped, the collet portion 42 is prevented from rotating with the mounting tube portion 41 because a bearing is provided between the push-in portion 41b and the collet portion 42. In other words, the occurrence of rotational behavior in the collet portion 42 is prevented, so that only a pressing force (clamping force) from the radial outside and a pulling force toward the axial rear end side can be applied to the cutting insert 2 via the collet portion 42. Therefore, the circumferential phase alignment and axial positioning of the cutting insert 2 can be performed with high accuracy, and the load on each positioning element (such as the restricting portion 34 and the locking portion 25) is reduced.

[0081] In addition, in the above-described embodiment and each modified example, the cutting insert 2 is an integrated type made of, for example, a cemented carbide, but the present invention is not limited to this. 10 is a top view showing a part of an indexable cutting tool 1F of a fifth modified example. In this modified example, the cutting insert 2 has an insert shank 2a made of, for example, steel or cemented carbide and extending in an axial direction, and a cutting portion 2b made of, for example, cemented carbide and disposed at the axial tip of the insert shank 2a. The blade portion 2b is provided with a rake face 21, a clearance face 22, and a cutting edge 23. The blade portion 2b is fixed to the tip of the insert shank 2a by, for example, screwing or brazing. The blade portion 2b is located axially closer to the tip side than the holder 3 and the chuck mechanism 4. The insert shank 2a is provided with a cylindrical portion 24, a locking portion 25, and a contact portion 26. In this case, for example, the insert shank 2a can be made of a cheaper material that has higher toughness than the cutting portion 2b, thereby reducing tool costs and preventing damage to the locking portion 25 and the abutting portion 26.

[0082] The present invention may be combined with the various configurations described in the above-mentioned embodiments and modifications, and may include additions, omissions, substitutions, and other modifications, without departing from the spirit of the present invention. The present invention is not limited to the above-mentioned embodiments, but is limited only by the claims. [Industrial Applicability]

[0083] According to the indexable cutting tool of the present invention, the cutting insert can be accurately aligned with the holder, the cutting insert can be stably clamped, the cutting insert can be prevented from being displaced toward the tip side in the axial direction when clamped, and multiple types of cutting inserts having different diameters can be used with one type of holder, thereby improving versatility. Therefore, the cutting tool has industrial applicability. [Explanation of symbols]

[0084] 1A, 1B, 1C, 1D, 1E, 1F...Replaceable cutting tools 2...Cutting insert 3…Holder 4...Chuck mechanism 23…Cutting edge 24…Cylindrical part 25…Latching part 26...Contact part 31…Insertion hole 32...Holder cylinder 32a…Male thread 32b…Inner circumference tapered surface 33…Female screw hole 34. Regulatory Department 34a…Male thread member 34b...Pin member 35…Pin hole 41...Mounting tube part 41a…Female thread 41b...Pushing part 42…Collet part 42a…Slit 42b...Outer tapered surface 42c…Receiving part C…Central axis

Claims

1. A shaft-shaped cutting insert extending in an axial direction around a central axis; a columnar holder having an insertion hole into which the cutting insert is inserted and extending in the axial direction; a chuck mechanism that detachably fixes the cutting insert inserted into the insertion hole to the holder, The holder includes: a holder tubular portion located at a tip end portion of the holder in the axial direction, arranged coaxially with the insertion hole, and having a male thread portion on an outer circumferential surface; a restricting portion that contacts the cutting insert inside the insertion hole and restricts the rotation of the cutting insert about the central axis and the movement of the cutting insert toward the rear end side in the axial direction; a female screw hole that opens to an outer peripheral surface of the holder and to the insertion hole, and that is positioned toward a tip end side in the axial direction as it extends toward an inner side in a radial direction perpendicular to the central axis, the restricting portion is a male screw member that is screwed into the female screw hole and protrudes into the insertion hole, The cutting insert comprises: A cylindrical portion at least a portion of which is disposed inside the holder tube portion; a locking portion that comes into contact with the restricting portion; a cutting edge protruding toward a tip end side in the axial direction beyond the holder tubular portion, The chuck mechanism includes: a mounting tube portion having a female screw portion on an inner circumferential surface thereof that screws into the male screw portion; a cylindrical collet portion that is separate from the mounting cylindrical portion, that is disposed between the mounting cylindrical portion, the holder cylindrical portion, and the columnar portion in the radial direction, and that has a variable diameter; the holder tubular portion has an inner circumferential tapered surface whose inner diameter increases toward a tip end side in the axial direction, the collet portion has an outer diameter that increases toward a tip end side in the axial direction and has an outer peripheral tapered surface that is in slidable contact with the inner peripheral tapered surface, the mounting tube portion has a push-in portion capable of pushing the collet portion toward a rear end side in the axial direction when the amount of screwing between the male screw portion and the female screw portion is increased. Indexable cutting tool.

2. the collet portion has a plurality of slits arranged at intervals in a circumferential direction around the central axis, The diameter of the collet portion changes as the width of the slit decreases or increases. The indexable cutting tool according to claim 1 .

3. the collet portion has a receiving portion having a tapered surface shape that is disposed on an outer circumferential surface of the collet portion and that increases in diameter toward a rear end side in the axial direction, the push-in portion is disposed on an inner circumferential surface of the mounting tube portion, has a tapered surface shape that increases in diameter toward the rear end side in the axial direction, and is capable of pushing the receiving portion toward the rear end side in the axial direction. The indexable cutting tool according to claim 1 or 2.

4. The locking portion is provided on the cutting insert at intervals in the axial direction. The indexable cutting tool according to any one of claims 1 to 3.

5. The chuck mechanism has a bearing interposed between the pushing portion and the collet portion. The indexable cutting tool according to any one of claims 1 to 4.

6. The cutting insert comprises: An insert shank having an axial shape extending in the axial direction; a cutting edge portion disposed at a tip portion of the insert shank in the axial direction, The cutting edge is disposed on the blade portion, The insert shank has the cylindrical portion and the locking portion disposed thereon. The indexable cutting tool according to any one of claims 1 to 5.

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