JP2007245295A - Insert detachable-type drill - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an insert detachable-type drill capable of definitely and rigidly fixing an insert with a pair of clamping surfaces by elastically deforming a pair of jaws with a small force and preventing a drill body from deteriorating rigidity to thereby suppress the generation of vibration and cutting noise. <P>SOLUTION: In the insert detachable-type drill 10, a pair of the jaws 25, 25 protruding toward the tip sides are formed at a tip section of the drill body 20, an insert mounting seat 26 provided with clamping surfaces 28, 28 and a bottom 27 on mutually opposed surfaces between a pair of the jaws 25, 25 is formed, and the insert 40 is detachably mounted on the insert mounting seat 26. The insert mounting seat 26 is provided with a clamping screw that elastically deforms the jaw 25 so as to allow the clamping surfaces 28, 28 to be closer to each other, and two slits 30, 30 or more that extend toward the rear sides in the axial O direction are formed on the bottom 27. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an insert detachable drill in which an insert having a cutting edge at its tip is detachably attached to the tip of a drill body.

  2. Description of the Related Art Conventionally, as a cutting tool for drilling a workpiece, an insert detachable drill is used in which an insert having a cutting edge at the tip is detachably attached to the tip of the drill body. In this insert detachable drill, when the cutting blade is worn out by cutting the workpiece, only the insert can be replaced and used, and the cost of using the drill can be reduced (for example, Patent Document 1). reference.).

  In this type of insert detachable drill, a pair of jaws projecting to the distal end side is formed at the distal end portion of a generally cylindrical drill body rotated about an axis, and the portion between them is used as an insert mounting seat. The insert mounting seat is provided with a bottom portion orthogonal to the axis and a pair of clamp surfaces disposed so as to cross the bottom portion and face each other, and each of the pair of clamp surfaces. A pair of torque transmission surfaces are formed so as to be continuous with each other.

  A slit extending along the axis is formed at the bottom of the insert mounting seat, and the tip side portion of the drill body is divided into two so as to have a clamp surface and a torque transmission surface. On the insert mounting seat, a clamp screw that elastically deforms the pair of jaws so that the pair of clamp surfaces are close to each other is disposed so as to intersect the slit. The pair of jaws are elastically deformed with the rear end portion of the slit as a fulcrum.

  The insert mounted on the insert mounting seat is made of a hard material such as cemented carbide, and a cutting edge is formed at the tip of the insert mounting seat. A clamp receiving surface to be contacted and a torque receiving surface to be in contact with the torque transmitting surface are formed.

  Such an insert is inserted into an insert mounting seat formed on the tip side of the drill body, and the insert is elastically deformed by a clamp screw so that a pair of clamp surfaces are close to each other, whereby the insert becomes a tip part of the drill body. The insert detachable drill is configured.

The insert detachable drill configured in this way is rotated about the axis O and fed in the direction of the axis O to perform cutting so as to form a processed hole in the workpiece.
JP 2004-330391 A

By the way, in the conventional insert detachable drill, in order to ensure elastic deformation of the pair of jaws so that the clamp surfaces of the insert mounting seats are close to each other, the axial length of the slit formed in the bottom is increased. It is effective to position the fulcrum position when elastically deforming the pair of jaws on the rear end side.
In particular, in the case of a drill having a diameter of 20φ or more, the radial thickness of the pair of jaws also increases, making it difficult to elastically deform. Therefore, it is necessary to increase the axial length of the slit.

  However, when the length of the slit in the axial direction is increased, there is a problem that the rigidity of the drill body is insufficient, and when the drill is rotated at a high speed, vibrations are generated and the processed hole cannot be formed with high accuracy. . In addition, there is a problem that resonance occurs due to the natural frequency of the drill body and the cutting noise increases.

  The present invention has been made in view of such circumstances, and the insert body can be securely and firmly fixed by the pair of clamp surfaces by elastically deforming the pair of jaw portions with a small force, and the drill body. It is an object of the present invention to provide an insert detachable drill that can prevent the reduction of rigidity and suppress the generation of vibration and cutting noise.

  In order to solve the above-mentioned problems, the present invention provides a pair of jaws projecting toward the distal end side of the drill body at the distal end of the drill body that is rotated about an axis. Clamp surfaces are formed on the surfaces facing each other, and a bottom portion intersecting the clamp surface is formed between the pair of jaw portions, and the clamp surface and the bottom portion serve as an insert mounting seat, and the insert An insert detachable drill configured by detachably attaching an insert having a cutting edge at a tip to a mounting seat, wherein the jaw portion is arranged so that the clamp surfaces are close to each other. A clamp screw is provided for elastically deforming, and two or more slits extending toward the rear side in the axial direction are formed in the bottom portion. .

  According to the insert detachable drill of this configuration, since two or more slits are formed at the bottom of the insert mounting seat, the radial thickness of each jaw portion becomes thin, and elastic deformation easily occurs. Even if the direction length is shortened, the pair of clamp surfaces can be brought close to each other with a small force. Therefore, the rigidity of the drill body can be improved, vibration during high-speed rotation can be prevented and machining can be performed with high accuracy, and an increase in cutting sound due to resonance can be prevented.

  In addition, the axial length L of the slit is set in a range of 0.15 × D ≦ L ≦ 0.56 × D with respect to the drill outer diameter D, thereby the axial length of the slit. The length L is smaller than 0.15 × D, so that the fulcrum position when deforming the jaw is close to the clamp screw, and it is possible to prevent a larger force from being required when elastically deforming, and the slit The axial length L is larger than 0.56 × D, it is possible to prevent the drill body from having insufficient rigidity and easily generating vibration and cutting noise, while ensuring the rigidity of the drill body, The pair of jaws can be reliably elastically deformed by the clamp screw.

  Further, by forming the slit so as to be orthogonal to the clamp screw, a force when the clamp screw is screwed in acts so as to be orthogonal to the slit, thereby reliably elastically deforming the pair of jaw portions, The insert can be firmly fixed by the clamping surface.

  As described above, according to the present invention, the pair of jaws can be elastically deformed with a small force and the insert can be securely and firmly fixed by the pair of clamping surfaces, and the rigidity of the drill main body can be prevented from being reduced. It is possible to provide an insert detachable drill capable of suppressing the generation of cutting noise.

Hereinafter, an insert detachable drill according to an embodiment of the present invention will be described with reference to the accompanying drawings. FIGS. 1 to 3 show an insert detachable drill according to an embodiment of the present invention, and FIGS. 4 and 5 show an insert attached to the insert detachable drill.
As shown in FIG. 2, the insert detachable drill 10 is attachable to and detachable from a drill main body 20 having a substantially multi-stage columnar shape rotated about an axis O, and a distal end side (lower side in FIG. 1) of the drill main body 20. It is comprised with the insert 40 with which it is mounted | worn.

On the rear end side (the upper side in FIG. 1) of the drill body 20, a shank portion 21 is formed for attachment to the spindle end of the machine tool.
On the outer periphery of the tip side portion of the drill body 20, a pair of chip discharge grooves 23 that open to the tip surface 22 of the drill body 20 and twist toward the rear side in the drill rotation direction T as it goes toward the rear end side of the drill body 20; 23 is formed to be 180 ° rotationally symmetric with respect to the axis O.

A pair of jaw portions 25, 25 projecting toward the distal end side is formed on the distal end portion 24 of the drill body 20, and a portion sandwiched between the pair of jaw portions 25, 25 is connected to the insert mounting seat 26. Has been.
The insert mounting seat 26 faces the tip end side of the drill body 20 and is perpendicular to the axis O, and is erected from the bottom part 27 and is parallel to the axis O and intersects the tip surface 22 of the drill body 20. And a pair of clamping surfaces 28, 28. That is, the opposing surfaces of the pair of jaw portions 25 and 25 are the clamp surfaces 28 and 28, and the bottom portion 27 is formed between the pair of jaw portions 25 and 25, and the bottom portion 27 and the clamp surfaces 28 and 28 are Constitutes the insert mounting seat 26.

  Each of the pair of jaws 25, 25 is formed with torque transmission surfaces 29, 29 that stand from the bottom 27 and intersect the tip surface 22 of the drill body 20 and continue to the respective clamp surfaces 28. . The pair of torque transmission surfaces 29 and 29 are formed so as to be 180 ° rotationally symmetric with respect to the axis O so as to face the front side of the drill rotation direction T. That is, one of the pair of clamping surfaces 28 and one of the pair of torque transmission surfaces 29 are positioned on one of the pair of jaws 25, and the pair of clamping surfaces 28 are positioned on the other of the pair of jaws 25. The other of them and the other of the pair of torque transmission surfaces 29 are positioned.

  More specifically, as shown in FIG. 3, clamp surfaces 28 and 28 are formed in the vicinity of the axis O of the pair of jaw portions 25 and 25 so as to face each other. A torque transmission surface 29 extending toward the outer side of the main body 20 in the radial direction and the rear side in the drill rotation direction T is formed, and the crossing angle in a cross section perpendicular to the axis O between the clamp surface 28 and the torque transmission surface 29 intersecting each other is It is set within the range of 90 ° to 120 °.

  Further, the torque transmission surface 29 is opposite to the side intersecting the clamp surface 28 with the outer peripheral surface of the drill body 20, whereas the clamp surface 28 is opposite to the side intersecting the torque transmission surface 29. The side crosses the wall surface of the chip discharge groove 23 facing the rear side in the drill rotation direction T without reaching the outer peripheral surface of the drill body 20.

  Further, the pair of clamp surfaces 28 and 28 are slightly inclined so as to go outward in the radial direction of the drill body 20 as they go to the rear end side of the drill body 20 (the inclination angle with respect to the axis O is greater than 0 ° and less than 1 °). The pair of torque transmission surfaces 29 and 29 are inclined so as to be directed forward in the drill rotation direction T toward the rear end side of the drill body 20 (the inclination angle with respect to the axis O is 0 °). Larger range of 30 ° or less). When viewed in a cross section perpendicular to the axis O, the pair of torque transmission surfaces 29 and 29 are extended so as to be substantially along the diameter direction passing through the axis O.

  An insertion hole (not shown) that is recessed toward the rear end side of the drill body 20 is formed in the bottom portion 27 facing the front end side of the drill body 20 in the insert mounting seat 26, and this insertion hole has a circular cross section with the axis O as the center. The inner peripheral surface is formed so as to be located radially inward of the wall surface of the drill body 20 in the radial direction of the chip discharge grooves 23 and 23 so that the insertion hole and the chip discharge groove 23 do not communicate with each other. Is arranged.

As shown in FIG. 2, two slits 30, 30 extending in parallel with the axis O toward the rear end side of the drill body 20 are formed in the bottom portion 27 so as to open to the chip discharge grooves 23, 23. ing. The two slits 30 and 30 are formed so as to be parallel to each other on the opposite side with respect to the axis O, and to have the same distance from the axis O, that is, arranged 180 degrees rotationally symmetrical about the axis O. ing.
At the rear end portion of the drill body 20 of these slits 30, 30, notch portions 31, 31 having a width larger than the width of the slits 30, 30 (distance between a pair of opposing wall surfaces constituting the slit 30). Is formed.

By these two slits 30, 30, a central band portion 32 is formed between the bottom portion 27 of the insert mounting seat 26, that is, between the pair of jaw portions 25, 25, with both side surfaces forming the wall surfaces of the two slits 30, 30. The distal end portion 24 of the drill body 20 is divided into three portions, that is, a pair of jaw portions 25 and 25 and a central belt portion 32 by two slits 30 and 30. Thereby, the radial direction thickness of the jaw part 25 in the part in which the slit 30 was formed is made small compared with the case where only one slit 30 is formed.
In the present embodiment, the lengths of the two slits 30 and 30 in the axis O direction are equal to each other and within the range of 0.15 × D ≦ L ≦ 0.56 × D with respect to the drill outer diameter D. It is set to be.

In addition, the distal end portion 24 of the drill body 20 has an insertion hole 34 for disposing a clamp screw 33 having a male screw portion at one end and a head having a larger diameter than the male screw portion at the other end. Is formed. This insertion hole 34 is formed so as to cross the insert mounting seat 26 and extend in the diametrical direction passing through the axis O and penetrate the tip 24, and its outer peripheral end is opened to the outer peripheral surface of the drill body 20. ing. Here, a female screw portion (not shown) into which the male screw portion is screwed is formed in the insertion hole 34 formed in one jaw portion 25, and the insertion hole 34 formed in the other jaw portion 25 is A large-diameter hole (not shown) in which the head is slidable is formed, and a stop member 35 having a cylindrical shape whose outer diameter is smaller than that of the head is formed in the outer peripheral end opening of the large-diameter hole. It is fixed. The inner peripheral hole of the stop member 35 is sized so that the engagement hole formed in the end face of the head is exposed to the outside.
The insertion hole 34 is formed so as to extend in a direction orthogonal to the slits 30, 30, and the clamp screw 33 is disposed in a direction orthogonal to the two slits 30, 30.

  Further, a coolant supply portion 36 is formed at the distal end portion 24 of the drill body 20 by cutting out an outer peripheral surface of the drill body 20 defined between the pair of chip discharge grooves 23, 23. The supply portion 36 is provided with a coolant hole 37 that extends along the axis O from the rear end side of the drill body 20 and branches in the middle thereof.

Next, the insert 40 attached to the drill main body 20 described above will be described. The insert 40 is made of a hard material such as cemented carbide, and the distal end surface 41 of the insert 40 has a convex V shape that is convex toward the distal end side (left side in FIG. 5).
Further, in a state where the insert 40 is mounted on the insert mounting seat 26, a substantially concave curved surface shape that smoothly faces the front end side of the chip discharge groove 23 facing the front side of the drill rotation direction T, and the front end surface 41 of the insert 40, A surface intersecting the rear end surface 42 of the insert 40 facing the rear end side of the drill body 20 and orthogonal to the axis O and the outer peripheral surface 43 of the insert 40 facing the outer side in the radial direction of the drill body 20 are a pair of rake surfaces 44, 44. It is said that. Cutting edges 45, 45 are formed at intersection ridges between the pair of rake surfaces 44, 44 and the tip surface 41 of the insert 40, respectively.

  Further, the insert 40 is formed with a pair of clamp receiving surfaces 46, 46 that intersect the front end surface 41 and the rear end surface 42, and a pair of torque receiving surfaces 47, 47 that also intersect the front end surface 41 and the rear end surface 42. Has been. In a state in which the insert 40 is mounted on the insert mounting seat 26, the pair of clamp receiving surfaces 46, 46 are disposed on opposite sides of the axis O so as to face the radially outer side of the drill body 20, and a pair of torques. The receiving surfaces 47, 47 are arranged on opposite sides of the axis O so as to face the rear side in the drill rotation direction T, respectively.

  Here, the pair of clamp receiving surfaces 46, 46 are arranged in the vicinity of the axis O, and intersect the respective drill rotation direction T rear side and the drill body 20 radial outer side of the pair of clamp receiving surfaces 46, 46. A pair of torque receiving surfaces 47 and 47 are formed, and the crossing angle in a cross section perpendicular to the axis O between the clamp receiving surface 46 and the torque receiving surface 47 intersecting each other is set within a range of 90 ° to 120 °. The crossing angle between the clamp surface 28 and the torque transmission surface 29 in the insert mounting seat 26 is approximately the same.

  Further, the torque receiving surface 47 is opposite to the outer surface 43 of the insert 40 on the opposite side to the side that intersects the clamp receiving surface 46, whereas the clamp receiving surface 46 is on the side that intersects the torque receiving surface 47. The opposite side does not reach the outer peripheral surface 43 of the insert 40 and intersects with a rake face 44 facing the front side in the drill rotation direction T.

  Further, the pair of clamp receiving surfaces 46, 46 are inclined so as to go outward in the radial direction of the drill body 20 as they go to the rear end side of the drill body 20 (the inclination angle with respect to the axis O is greater than 0 ° and less than 1 °). Within the range, the pair of torque receiving surfaces 47 and 47 are each rotated toward the rear end side of the drill body 20 in accordance with the rotation direction T of the drill. It is inclined to the front side (with the inclination angle with respect to the axis O being larger than 0 ° and not more than 30 °, substantially the same value as the inclination angle of the torque transmitting surface 29 in the insert mounting seat 26). . When viewed in a cross section perpendicular to the axis O, the pair of torque receiving surfaces 47 and 47 are arranged so as to be substantially along the diameter direction passing through the axis O.

  As shown in FIG. 5, the rear end face 42 of the insert 40 is formed with a shaft portion 48 having a circular cross section projecting toward the rear end side. The outer diameter of the shaft portion 48 is the same as that of the shaft portion 48. The outer peripheral surface is sized so as to be located on the radially inner side of the rake face 44 with respect to the intersection of the insert 40 with the rear end face 42.

Next, a procedure for mounting the insert 40 having such a configuration on the insert mounting seat 26 formed at the distal end portion 24 of the drill body 20 will be described.
First, when the clamp screw 33 arranged in the insertion hole 34 is rotated so as to be loosened, the clamp screw 33 moves from the female screw part formed in the insertion hole 34 of one jaw part 25 to the other jaw part 25 side. Then, the head of the clamp screw 33 is brought into contact with the stop member 35, and the rear end portions (notch portions 31, 30) of the slits 30 and 30 are arranged so that the one jaw portion 25 and the other jaw portion 25 are separated from each other. 31) is elastically deformed with the fulcrum as a fulcrum, and the pair of clamp surfaces 28 are separated from each other.

  The rear end of the drill body 20 is inserted into the insert mounting seat 26 thus expanded so that the pair of clamp receiving surfaces 46 and 46 and the pair of clamp surfaces 28 and 28 of the drill body 20 face each other. Slide to the side and insert. At this time, the shaft portion 48 formed on the rear end surface 42 of the insert 40 is inserted into the insertion hole formed in the bottom portion 27 of the insert mounting seat 26, and the rear end surface 42 of the insert 40 and the bottom portion 27 of the insert mounting seat 26 are Are in close contact with each other. Further, the rake surfaces 44, 44 of the insert 40 are respectively directed to the front side of the drill rotation direction T so as to be continuous with the chip discharge grooves 23, 23, and the torque receiving surfaces 47, 47 and the torque transmission surfaces 29, 29 are arranged so as to face each other.

  When the clamp screw 33 is screwed in the state where the insert 40 is inserted in this manner, the rear end portions (notches 31 and 31) of the slits 30 and 30 are used as fulcrums so that the pair of jaw portions 25 and 25 come close to each other. The insert 40 is clamped by the pair of clamp surfaces 28 and 28 by elastically deforming and pressing the clamp receiving surfaces 46 and 46 of the insert 40 by bringing the pair of clamp surfaces 28 and 28 close to each other. Furthermore, the insert 40 is firmly fixed when the outer peripheral surface of the shaft portion 48 and the inner peripheral surface of the insertion hole are in close contact with each other. In this way, the insert 40 is mounted on the insert mounting seat 26, and the insert detachable drill 10 is configured.

  In the insert detachable drill 10 configured as described above, the shank portion 21 is held at the spindle end of a machine tool (not shown), rotated around the axis O, and fed in the direction of the axis O. Cutting is performed so as to form a processed hole in the cutting material.

  According to the insert detachable drill 10 according to this embodiment, two slits 30 and 30 are formed in the bottom portion 27 of the insert mounting seat 26, and the distal end portion 24 of the drill body 20 is connected to the pair of jaw portions 25 and 25. Since it is divided into three parts with the central belt part 32, the radial thickness of each jaw part 25 becomes thin and is easily elastically deformed, and even if the length of the slits 30 and 30 in the direction of the axis O is shortened. The pair of jaw portions 25 and 25 can be elastically deformed with a small force to bring the pair of clamp surfaces 28 and 28 close to each other. Therefore, the rigidity of the drill main body 20 can be improved, vibration during high-speed rotation can be prevented and machining can be performed with high accuracy, and an increase in cutting sound due to resonance can be prevented.

Moreover, since the length L in the axis O direction of the slit 30 is set within the range of 0.15 × D ≦ L ≦ 0.56 × D with respect to the drill outer diameter D, the rigidity of the drill body 20 is increased. While securing, the pair of jaws 25, 25 can be reliably elastically deformed by the clamp screw 33.
Further, since the clamp screw 33 is arranged so as to be orthogonal to the slits 30, 30, the pressing force when the clamp screw 33 is screwed or loosened acts so as to be orthogonal to the slits 30, 30. The jaws 25 and 25 can be reliably elastically deformed, and the insert 40 can be firmly fixed by the pair of clamp surfaces 28 and 28.

Although the insert detachable drill according to the embodiment of the present invention has been described above, the present invention is not limited to this embodiment, and can be appropriately changed without departing from the technical idea of the present invention.
For example, the shaft portion is formed on the rear end surface of the insert and the insertion hole is formed in the bottom portion of the insert mounting seat, but the shaft portion and the insertion hole may not be formed.

Furthermore, the shape of the insert is not limited to this embodiment, and for example, a flat plate-like insert may be clamped and fixed.
Moreover, although it demonstrated by what formed two slits, it is not limited to this, You may formed three or more.

Below, the result of the comparative experiment performed in order to confirm the effect of this invention is demonstrated. As an example of the present invention, in the insert detachable drill according to the above-described embodiment, a drill having an outer diameter D of 10 mm and an axial length L of the slit of 3.5 mm was subjected to an experiment.
As a comparative example, an insert detachable drill having a drill body having a drill outer diameter D equal to that of the present invention and having only one slit having an axial length L of 6.0 mm was used for the experiment. In addition, the thing of the same shape and material was used for the insert in the present invention example and the comparative example.

Using these insert detachable drills, cutting sound was measured when carbon steel as a work material was cut at a cutting speed Vc = 120 m / min and a feed speed of 0.3 m / min. Measurements were made four times with each insert detachable drill, and the measured values were compared.
Table 1 shows the results of the comparative experiment.

  As shown in Table 1, it was confirmed that according to the example of the present invention, cutting noise can be suppressed as compared with the comparative example.

It is a side view of an insert detachable drill which is an embodiment of the present invention. It is a X direction arrow line view in FIG. It is a Y direction arrow directional view in FIG. It is a front view of the insert with which the insert detachable drill shown in FIG. 1 is mounted. It is a side view of the insert shown in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Insert detachable drill 20 Drill main body 25 Jaw part 26 Insert mounting seat 27 Bottom part 28 Clamp surface 30 Slit 33 Clamp screw 40 Insert 45 Cutting blade

Claims (3)

A pair of jaws projecting toward the tip side of the drill body is formed at the tip of the drill body rotated about the axis, and a clamp surface is formed on each of the opposing surfaces of the pair of jaw parts. In addition, a bottom portion that intersects with the clamp surface is formed between the pair of jaw portions, the clamp surface and the bottom portion serve as an insert mounting seat, and an insert having a cutting edge at the tip is provided on the insert mounting seat. An insert detachable drill configured by being detachably mounted,
The insert mounting seat includes a clamp screw that elastically deforms the jaw portion so that the clamp surfaces are close to each other, and two or more slits extending toward the rear side in the axial direction are formed on the bottom portion. An insert detachable drill characterized by being made.   The axial length L of the slit is set in a range of 0.15 × D ≦ L ≦ 0.56 × D with respect to a drill outer diameter D. Insert detachable drill.   The insert detachable drill according to claim 1 or 2, wherein the slit is formed so as to be orthogonal to the clamp screw.

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