JP2008161999A - Cutting tool - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cutting tool capable of improving service life of a cutting insert by effectively utilizing a cutting edge of the cutting insert mounted on a chamfering machining part. <P>SOLUTION: The cutting tool 10 is inserted in a prepared hole previously provided on a workpiece and an inner wall surface of the prepared hole is machined to form a machined hole for the cutting insert. The chamfering machining part 16 for applying chamfering machining for a peripheral edge of an opening part of the machined hole is provided on a tool body 11 rotating around an axis line O, a plurality of mounting seats capable of mounting the cutting insert 30 for chamfering machining of the same shape and same size is provided and the respective cutting inserts 30 for chamfering machining mounted on these mounting seats 22 are constituted so that a different part of the cutting edge 33 of the one to each other is used for the chamfering machining. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention is inserted into a prepared hole formed in a workpiece, and the inner wall surface of the prepared hole is cut to form a processed hole having a predetermined inner diameter, and the periphery of the opening of the processed hole is chamfered. It relates to a cutting tool.

As a cutting tool for performing the processing as described above, for example, as described in Patent Document 1, a cutting blade portion is provided at a tip portion of a tool body rotated around an axis, and a rear end of the cutting blade portion. A chamfering portion is provided in the side portion, and a chamfering blade inclined with respect to the axis is arranged in this chamfering portion so as to go radially outward as it goes to the rear end side of the tool body. ing. In such a cutting tool, the tool body is rotated around the axis while being fed toward the tip end side in the axial direction, so that a machining hole is formed by the cutting edge portion and an opening portion of the machining hole is formed by the chamfering blade. The periphery is chamfered.
Japanese Utility Model Publication No. 58-40311

By the way, in the cutting tool as described above, when a cutting insert is attached to a chamfered portion and a cutting edge formed on a side ridge portion of the rake face of the cutting insert is used as the chamfering blade, one side ridge is formed. The cutting edge formed in the part is placed as a chamfering blade so as to be inclined with respect to the axis, and chamfering is performed with this cutting edge, and when this cutting edge is worn, a corner change is performed to another edge part. The formed cutting blade will be used. In other words, the cutting blade formed on one side ridge is used only once as a chamfering blade.
Here, when chamfering the periphery of the opening of the processing hole, only a part of the cutting edge may be used for cutting if the amount of cutting is small. In this case, even though only a part of the cutting blade is used and there are many parts that are not used for cutting, corner changes will be performed, and the service life of the cutting insert will be shortened. End up.

  The present invention has been made in view of the above circumstances, and a cutting tool capable of improving the service life of a cutting insert by effectively using the cutting blade of the cutting insert attached to a chamfered portion. The purpose is to provide.

  In order to solve this problem, the cutting tool of the present invention is inserted into a prepared hole provided in advance in a workpiece, and cuts an inner wall surface of the prepared hole to form a processed hole having a predetermined inner diameter. A tool body that is rotated around an axis is provided with a chamfering portion for chamfering the periphery of the opening of the processing hole, and the chamfering portion has a chamfering cutting insert of the same shape and size. In the chamfering cutting inserts attached to these mounting seats, different parts of the one cutting blade are used for chamfering. It is characterized by being.

  In the cutting tool according to the present invention, a plurality of mounting seats to which a chamfering cutting insert of the same shape and size can be attached are formed in a chamfering portion to be chamfered, and the chamfering processing is attached to these mounting seats. Since cutting parts for cutting use are configured so that different parts of one cutting edge are used for chamfering, the cutting edge position when the cutting insert for chamfering is attached to one mounting seat and other The cutting blade position at the time of mounting on the mounting seat will shift, and it becomes possible to use the cutting blade formed on one side ridge part of the cutting insert for chamfering processing attached to a plurality of mounting seats, A cutting blade formed on one side ridge can be used multiple times as a chamfering blade. Thereby, the lifetime extension of the cutting insert can be aimed at.

Here, the chamfering cutting insert may be attached to a part of the attachment seat, and the dummy insert may be attached to the remaining attachment seats.
In this case, the remaining mounting seat to which the chamfering cutting insert is not attached can be prevented from being damaged by scraping of chips, a collision at the time of handling, or the like, and the life of the cutting tool can be extended. Furthermore, it is possible to improve the weight balance of the tool main body by mounting the dummy insert, and it is possible to perform machining with high dimensional accuracy by preventing the axis from swinging when the tool main body rotates.

Further, a pilot hole machining mounting seat for attaching a pilot hole machining cutting insert for machining the pilot hole is provided closer to the tip side of the tool body than the chamfering, and the pilot hole machining cutting insert is attached to the chamfer. As the same shape and size as the cutting insert for processing, a portion different from the portion used for the chamfering may be used for processing the pilot hole.
In this case, one type of cutting insert can be used as a chamfering blade as a cutting blade for cutting the inner wall surface of the pilot hole, and the management cost of the cutting insert can be greatly reduced. In addition, use the cutting edge of the corner part of the cutting insert when it is mounted on the mounting seat for prepared holes, and use the cutting edge of the side edge of the cutting insert when it is mounted on the mounting seat of the chamfered part. By comprising, it becomes possible to use one cutting insert also as a cutting blade for pilot hole processing, and the lifetime extension of the cutting insert can be aimed at further.

  ADVANTAGE OF THE INVENTION According to this invention, the cutting tool which can use the cutting blade of the cutting insert attached to a chamfering process part effectively, and can improve the service life of a cutting insert can be provided.

The cutting tool which is embodiment of this invention is demonstrated with reference to attached drawing. FIG. 1 shows a boring bar which is an embodiment of the present invention.
The boring bar 10 has a tool body 11 having a substantially multi-stage cylindrical shape extending along the axis O. A mounting portion 12 for mounting the tool body 11 to a spindle end (not shown) of a machine tool or the like is formed on the rear end side (upper side in FIG. 1) of the tool body 11. The mounting portion 12 is provided with a cut-out surface 13 for guiding the circumferential position of the tool body 11 when mounted on the spindle end.

On the distal end side of the tool body 11 of the mounting portion 12, there are a large-diameter portion 14 that projects larger outward than the mounting portion 12 in the radial direction and a tapered portion 15 that gradually decreases in diameter toward the distal end side of the tool body 11. A chamfered portion 16 is provided.
A cutting edge portion 17 for cutting an inner wall surface of a prepared hole formed in advance in the workpiece W is provided on the tip end side (lower side in FIG. 1) of the chamfered portion 16. .

  In the tool body 11, a chip discharge groove 20 that opens toward the tip surface of the tool body 11 (the cutting edge portion 17) and the outer peripheral surface of the tool body 11 extends along the axis O to the large diameter portion 14. It is provided to reach. In the present embodiment, the pair of chip discharge grooves 20A and 20B are disposed so as to be 180 ° rotationally symmetric about the axis O.

  At the tip of the cutting edge portion 17, a pilot hole machining seat 21 for attaching a cutting insert 30 to be described later is formed on the wall surface of the chip discharge groove 20 facing the front side in the tool body rotation direction. Each of the pair of chip discharge grooves 20A, 20B is provided with one pilot hole mounting seat 21. In the tool body 11, the pair of pilot hole processing seats 21A, 21B is centered on the axis O. As shown in FIG.

And the 1st mounting seat 22A for attaching the cutting insert 30 which performs a chamfering process is formed in the part of the chamfering process part 16 of 20A of one chip | tip discharge groove | channel. Moreover, the 2nd mounting seat 22B for attaching the cutting insert 30 which chamfers also in the part of the chamfering process part 16 of the other chip discharge groove | channel 20B is formed. That is, in this embodiment, the two mounting seats 22 are provided in the chamfered portion 16.
Here, the 2nd mounting seat 22B is formed so that it may be located in the tool body 11 tip end side rather than the 1st mounting seat 22A, and the tool body 11 radial inside. More specifically, the axial line O-direction distance L1 from the tool body 11 tip surface to the first mounting seat 22A and the axial line O-direction distance L2 to the second mounting seat 22B are set so that L1> L2, The radial distance R1 to the first mounting seat 22A and the radial distance R2 to the second mounting seat 22B are set to satisfy R1> R2.

The cutting insert 30 in the present embodiment is formed of a hard material such as cemented carbide, for example, and has an outer shape of a substantially equilateral triangular plate, and includes a pair of equilateral triangular surfaces 31 and three side surfaces 32. . A straight cutting edge 33 is formed at the intersection ridge line portion between the equilateral triangular surface 31 and the side surface 32, and a corner cutting edge 34 is formed at the corner portion of the equilateral triangular surface 31. A clamp screw insertion hole (not shown) penetrating in the thickness direction of the cutting insert 30 is formed in the center of the equilateral triangular surface 31.
The cutting insert 30 in the present embodiment is a so-called negative type in which the equilateral triangular surface 31 and the side surface 32 are configured to be orthogonal to each other, and the straight cutting edge 33 and the corner cutting edge 34 are not provided with clearance angles. ing.

  The dummy insert 40 is formed of a hard material such as a cemented carbide, for example, similarly to the cutting insert 30 described above, and the outer shape thereof has a substantially triangular flat plate shape. Here, the triangular surface 41 has a shape in which one side ridge portion of the regular triangle is slightly retracted to the inside of the triangular surface. In the present embodiment, as shown in FIG. 4, the retreat amount of the retreated side ridge portion 42 is δ. The triangular surface 41 is provided with a clamp screw insertion hole (not shown) penetrating in the thickness direction of the dummy insert 40.

  In the prepared holes 21A and 21B, the above-mentioned cutting insert 30 is provided so that one corner cutting edge 34 protrudes radially outward of the tool body 11 and toward the distal end side of the tool body 11, and The linear cutting blade 33 is arranged so as to face the tip side of the tool body 11 and is fixed by a clamp screw 50. Here, since the pair of prepared holes 21A and 21B are formed so as to be 180 ° rotationally symmetric about the axis O, the cutting inserts 30 respectively attached to the prepared holes 21A and 21B are prepared. The rotation trajectories about the axis O of one straight cutting edge 33 and one corner cutting edge 34 coincide with each other.

  In the first mounting seat 22A provided in the chamfered portion 16, the cutting insert 30 has an axis O such that one straight cutting edge 33 gradually goes inwardly in the radial direction of the tool body 11 as it goes toward the tip side of the tool body 11. And is fixed by a clamp screw 50. When the cutting insert 30 is attached to the first attachment seat 22A, as shown in FIG. 2, portions of the one straight cutting edge 33 that are located on the distal end side of the tool body 11 and on the radially inner side of the tool body 11 are processed holes. Will be pressed against the periphery of the opening.

  In the second mounting seat 22B provided in the chamfered portion 16, the above-described dummy insert 40 is gradually moved inwardly in the radial direction of the tool body 11 as the retracted side ridge portion 42 moves toward the distal end side of the tool body 11. Are arranged so as to be inclined with respect to the axis O and fixed by a clamp screw 50. Then, in the rotation locus about the axis O, the side edge of the dummy insert 40 attached to the second mounting seat 22B rather than the one linear cutting blade 33 of the cutting insert 30 attached to the first mounting seat 22A. The part 42 is configured so as to recede by δ toward the inside in the radial direction of the tool body 11 and the rear end side of the tool body 11 so that the dummy insert 40 does not contact the peripheral edge of the opening of the machining hole.

  Here, when the cutting insert 30 attached to the first attachment seat 22A and the dummy insert 40 attached to the second attachment seat 22B are exchanged, the cutting insert 30 is placed on the second attachment seat 22B in a straight line. The cutting blade 33 is attached so as to be inclined with respect to the axis O so as to gradually go inward in the radial direction of the tool body 11 as it goes toward the tip side of the tool body 11. Then, the rotation trajectory of the straight cutting edge 33 is on a straight line, and different portions of the straight cutting edge 33 are used for chamfering. More specifically, since the second mounting seat 22B is located on the distal end side of the tool body 11 and the inner side in the radial direction of the tool body 11 with respect to the first mounting seat 22A, as shown in FIG. Of these, the part located on the rear end side of the tool body 11 and the outer side in the radial direction of the tool body 11 is pressed against the periphery of the opening of the machining hole. Further, the dummy insert 40 is inclined to the first mounting seat 22A with respect to the axis O so that the retracted side ridge portion 42 gradually goes inward in the radial direction of the tool body 11 as it goes toward the tip end side of the tool body 11. It is attached in this way.

  In the boring bar 10 having such a configuration, the mounting portion 12 is mounted on the spindle end of the machine tool, rotated around the axis O, and sent toward the front end side in the axis O direction. The inner wall surface of the prepared hole is cut by the corner cutting edge 34 of the cutting insert 30 attached to the prepared hole processing seats 21A and 21B to form a processed hole having a predetermined inner diameter. The chamfering process is performed on the periphery of the opening of the processing hole by the straight cutting edge 33 of the cutting insert 30 attached to either the first mounting seat 22A or the second mounting seat 22B formed in the chamfering processing portion 16. Apply.

According to the boring bar 10 of the present embodiment, the second mounting seat 22B formed on the chamfered portion 16 is positioned on the tip side of the tool body 11 and on the radially inner side of the tool body 11 with respect to the first mounting seat 22A. Since it is arranged, the position of the straight cutting edge 33 when the cutting insert 30 is attached to the first attachment seat 22A and the position of the straight cutting edge 33 when attached to the second attachment seat 22B are shifted, One straight cutting edge 33 of the cutting insert 30 can be used twice as a chamfering edge.
Here, in this embodiment, since the cutting insert 30 is a negative type insert having a regular triangular flat plate shape and includes six straight cutting edges 33, one cutting insert 30 is used 12 times as a chamfering edge. can do.

  Furthermore, since the dummy insert 40 is attached to the attachment seat 22 to which the cutting insert 30 is not attached among the first attachment seat 22A and the second attachment seat 22B, the attachment seat 22 can be prevented from being damaged by chips or the like. Further, by attaching a dummy insert 40 formed of a hard material such as cemented carbide like the cutting insert 30, it is possible to improve the weight balance of the tool body 11, and the axis when the tool body 11 rotates. It is possible to perform processing with good dimensional accuracy by preventing O shake.

  Furthermore, in this embodiment, since it is comprised so that the cutting insert 30 attached to the 1st attachment seat 22A and the 2nd attachment seat 22B can be attached also to the attachment holes 21A and 21B for pilot hole processing, this one kind The cutting insert 30 can be used as a chamfering blade as a cutting blade for cutting the inner wall surface of the pilot hole, and the management cost of the cutting insert 30 can be greatly reduced.

  Further, the corner cutting edge 34 of the cutting insert 30 is used when mounted on the pilot hole machining seats 21A and 21B, and the straight cutting edge 33 is used when mounted on the first mounting seat 22A and the second mounting seat 22B. By configuring as described above, it becomes possible to use one cutting insert 30 for the drilling of the pilot hole, and it is possible to further extend the life of the cutting insert 30. In this embodiment, the cutting insert 30 is a negative type insert having an equilateral triangular flat plate shape and includes six straight cutting edges 33 and six corner cutting edges 34. Therefore, one cutting insert 30 is provided. While being used 12 times as a chamfering blade, it can be used 6 times as a cutting blade for drilling a pilot hole.

As mentioned above, although embodiment of this invention was described, this invention is not limited to this, It can change suitably in the range which does not deviate from the technical idea of the invention.
For example, although the present embodiment has been described on the assumption that a cutting insert having a regular triangular flat plate shape is attached, the shape of the cutting insert is not limited, and a cutting insert having another shape such as a polygonal flat plate shape may be attached.
Moreover, although it demonstrated as a negative type insert, it is not limited to this, It is good also as a positive type with which the clearance angle was attached | subjected.

Moreover, although the cutting insert attached to the mounting seat for pilot hole processing and the cutting insert attached to the mounting seat for chamfering processing were explained as having the same shape and size, the shape of the cutting insert may be different.
Further, although it has been described that the cutting insert is attached to one of the chamfering mounting seats and the dummy insert is attached to the other, the dummy insert need not be attached.

Further, the cutting blade for machining the pilot hole may be one in which the cutting blade is fixed to the tool body by brazing or the like without using a detachable cutting insert.
Furthermore, although a pair of chip discharge grooves were formed and explained as one in which each chip discharge groove was provided with a pilot hole machining mounting seat and a chamfering mounting seat, the pilot hole machining mounting seat is 1 One or three or more may be formed.

It is a side view of the boring bar which is an embodiment of the present invention. It is explanatory drawing which shows the state which mounted | wore the cutting insert in the 1st attachment seat formed in the chamfering process part of the boring bar shown in FIG. It is explanatory drawing which shows the state which mounted | wore the cutting insert in the 2nd mounting seat formed in the chamfering process part of the boring bar shown in FIG. It is explanatory drawing which shows the state which mounted | worn with the insert for dummy in the 2nd mounting seat formed in the chamfering process part of the boring bar shown in FIG.

Explanation of symbols

10 Boring bar (cutting tool)
DESCRIPTION OF SYMBOLS 11 Tool main body 16 Chamfering part 17 Cutting edge part 21A, 21B Mounting hole 22 for prepared holes 22 Mounting seat 30 Cutting insert 40 Dummy insert

Claims (3)

A cutting tool that is inserted into a prepared hole provided in advance in a workpiece, and forms a processed hole with a predetermined inner diameter by cutting an inner wall surface of the prepared hole,
The tool body rotated around the axis is provided with a chamfering portion for chamfering the periphery of the opening of the machining hole. A plurality of chamfering cutting inserts of the same shape and the same size can be attached to the chamfering portion. The mounting seat is formed,
A cutting tool characterized in that the chamfering cutting inserts attached to these mounting seats are configured such that different portions of the one cutting blade are used for chamfering.   The cutting tool according to claim 1, wherein the chamfering cutting insert is attached to a part of the mounting seat, and the dummy insert is attached to the remaining mounting seat. On the tip side of the tool body from the chamfering process, a pilot hole machining mounting seat for mounting a pilot hole machining cutting insert for machining the pilot hole is provided,
The pilot hole machining cutting insert has the same shape and size as the chamfering machining insert, and a part different from the part used for the chamfering process is used for machining the pilot hole. The cutting tool according to claim 1 or 2.

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