JP2008018477A - Boring tool - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a boring tool which prevents run-out during high-speed rotation to form a machined hole with good accuracy, and also prevents breakage to extend the life. <P>SOLUTION: The boring tool 20 is inserted in a prepared hole to form a machined hole. The boring tool includes: a shank part where a coolant feed hole is bored in the interior; and a knife edge part 22 having a cutting blade 27. A plurality of chip discharge grooves 26 are formed on the outer periphery of the knife edge part 22, the cutting blade 29 is formed at an intersecting ridge part of the wall surface of the chip discharge groove 26, which is directed to the forward side in the tool rotating direction T and the outer peripheral surface of the knife edge part 22, and a guide part 30 brought into sliding contact with the inner wall surface of the machined hole, is provided in back of each chip discharge groove 26 in the tool rotating direction T. The guide part 30 is provided with an oil groove part 32 to which a coolant discharge hole 35 retreated toward the radial inside of the knife edge part 22 and communicated with the coolant feed hole is opened, and these coolant discharge holes 35 are disposed in different positions in direction of an axis O. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a hole machining tool that is inserted into a prepared hole formed in advance in a workpiece, and is used when a hole having a predetermined inner diameter is formed by cutting an inner wall surface of the prepared hole.

As this type of drilling tool, for example, a reamer having a long cylindrical shape as described in Patent Document 1 is known.
This reamer is used by being mounted on, for example, a cutting tool disclosed in Patent Document 2, and this cutting tool is mounted on a spindle end of a machine tool or the like and rotated around an axis, The hole machining tool is inserted into a pilot hole of the material, such as a stem guide hole or a valve hole in an engine cylinder head, and the inner wall surface of the pilot hole is cut to form a machining hole having a predetermined inner diameter. .

An example of a conventional reamer is shown in FIGS. The reamer includes a shank portion 1 having a long cylindrical shape, and a blade edge portion 2 disposed on the distal end side of the shank portion 1.
The shank portion 1 has a substantially multi-stage columnar shape, and a mounting portion 3 for mounting the reamer on a cutting tool is provided on the rear end side. On the other hand, a V-shaped groove 4 having a central portion recessed toward the rear end side of the shank portion 1 is formed on the front end surface of the shank portion 1.
In addition, a coolant supply hole (not shown) is formed in the shank portion 1 so as to penetrate from the front end side to the rear end side of the shank portion 1, and is opened in the V-shaped groove 4.

The blade edge portion 2 has a substantially cylindrical shape, and a convex portion 5 that can be fitted into a V-shaped groove 4 formed on the front end surface of the shank portion 1 is formed on the rear end surface thereof.
As shown in FIGS. 6 and 7, on the outer periphery of the tip of the blade edge portion 2, six chip discharge grooves extending toward the rear end side in the axis O direction and twisted at a predetermined angle toward the front side in the tool rotation direction T. 6 are arranged in 60-degree rotational symmetry with respect to the axis O at equal intervals in the circumferential direction.

A cutting edge 9 is formed at the intersecting ridge line portion between the wall surface 7 of the chip discharge groove 6 facing the front side in the tool rotation direction T and the outer peripheral surface 8 connected to the rear side in the tool rotation direction T. By forming the cutting edge 9 in this way, the wall surface 7 facing the front side in the tool rotation direction T of the chip discharge groove 6 is a rake face, and the outer peripheral surface 8 connected to the rear side in the tool rotation direction T is a flank face. .
As shown in FIG. 7, the chip discharge groove 6 has a V-shaped cross section in which the groove bottom has a concave arc shape. The angle formed by the V shape is approximately 80 °, and the tool is a rake face. The wall surface 7 facing the front side in the rotation direction T is formed so as to extend along the radial direction of the circle formed by the cross-section of the outline of the cutting edge portion 2.

Further, in the vicinity of the axis O of the blade edge portion 2, a communication hole (not shown) extending along the axis O and opened on the rear end side (the convex portion 5) is formed. A coolant discharge hole 10 extending to the chip discharge groove 6 and opened at the bottom of the groove is provided.
Here, in this reamer, the cutting fluid is discharged from the coolant discharge hole 10 through the coolant supply hole and the communication hole, so that the chips are caused to flow to the cutting fluid flowing in the chip discharge groove 6, and the reamer tip. It is configured to be discharged toward the side.
JP 2000-263328 A JP 2002-59313 A

  By the way, in the conventional reamer shown in FIG. 6 and FIG. 7, the outer peripheral surface 8 connected to the rear side of the tool discharge direction T of the chip discharge groove 6 is radially inward of the cutting edge portion 2 toward the rear side of the tool rotation direction T. Since a large relief is formed so that it moves backward, there is no part where the inner wall surface of the processing hole and the reamer are in sliding contact, and the reamer is shaken when the reamer is rotated at high speed in the processing hole, so that the processing hole is accurately There was a problem that it was impossible to mold.

  On the other hand, when the outer peripheral surface 8 is configured to be in sliding contact with the inner wall surface of the machining hole without providing a large relief, the rotational torque of the reamer is remarkably increased, and the reamer cannot be rotated at a high speed within the machining hole. There was a possibility that it could not be processed. Further, for example, in the case of a small-diameter reamer, the reamer may be broken starting from the portion where the coolant discharge hole 10 is formed due to excessive rotation torque.

  The present invention has been made in view of the above-described circumstances, and is capable of forming a machined hole with high accuracy by preventing runout during high-speed rotation, and capable of preventing breakage and extending the service life. The purpose is to provide.

  In order to solve this problem, the present invention is a hole machining tool that is inserted into a prepared hole that is formed in advance in a workpiece, and that forms a processed hole by cutting the inner wall surface of the prepared hole. A shank portion that is rotated around and has a coolant supply hole formed therein, and a cutting edge portion having a cutting edge, and the outer periphery of the cutting edge portion is directed from the front end side toward the rear end side. A plurality of extending chip discharge grooves are formed, and the cutting blades are formed on intersection ridges between a wall surface facing the front side in the tool rotation direction of the chip discharge grooves and the outer peripheral surface of the blade edge part, and each of the chip discharges A guide portion that slides in contact with the inner wall surface of the machining hole is provided behind the groove in the tool rotation direction, and the guide portion retreats inward in the radial direction of the cutting edge portion and communicates with the coolant supply hole. An oil groove with an open coolant discharge hole is provided. These coolant discharge holes is characterized in that it is arranged in different positions in the axial direction.

In the hole drilling tool having this configuration, a guide portion that is in sliding contact with the inner wall of the drilled hole is provided on the rear side in the tool rotation direction of the plurality of chip discharge grooves, so that the hole drilling tool is rotated at a high speed in the hole. Can be prevented, and the machined hole can be accurately formed.
In addition, an oil groove portion that recedes inward in the radial direction is formed in the guide portion, and a coolant discharge hole that communicates with the coolant supply hole is opened in the oil groove portion, so that the guide portion that is in sliding contact with the inner wall surface The cutting fluid can be supplied to the cylinder to improve lubrication, and the rotational torque of the drilling tool can be effectively reduced.

Further, since the coolant discharge holes respectively opened in the oil groove portions are arranged at different positions in the axial direction, a portion where the blade edge portion is perforated to form the coolant discharge holes is located at one place in the axial direction. Without concentrating, it is possible to prevent the drilling tool from being broken and to extend the life.
In addition, since the oil groove portion that is recessed toward the inside in the radial direction is formed in the guide portion, the size of the portion where the guide portion and the inner wall surface of the machining hole are in sliding contact is adjusted by adjusting the size of the oil groove portion. Therefore, it is possible to prevent vibration and reduce rotational torque.

  Here, the oil groove is opened toward the tip end in the axial direction, and the cutting oil supplied to the oil groove is configured by rounding up the rear end in the axial direction toward the radially outer side. Since it is reliably discharged toward the front side in the axial direction, lubrication between the guide portion in the vicinity of the cutting edge and the inner wall surface of the drilled hole is improved, and the drilling of the drilling tool is reliably prevented to perform cutting with high dimensional accuracy. In addition, it is possible to prevent the drilling tool from being broken by suppressing an increase in the rotational torque of the drilling tool.

  According to the present invention, it is possible to provide a drilling tool that can accurately form a machined hole by preventing runout during high-speed rotation, and can prevent breakage and extend the life.

Hereinafter, a drilling tool according to an embodiment of the present invention will be described with reference to the accompanying drawings. 1 to 4 show a reamer as a drilling tool according to an embodiment of the present invention. FIG. 5 shows a cutting tool to which this reamer is attached.
The reamer 20 includes a shank portion 21 having a long cylindrical shape, and a cutting edge portion 22 disposed on the tip side (lower side in FIG. 1) of the shank portion 21.

The shank portion 21 has a substantially multi-stage cylindrical shape centered on the axis O, and a mounting portion 23 for mounting the reamer 20 on a cutting tool 40 described later is provided on the rear end side (upper side in FIG. 1). Is provided. The mounting portion 23 is provided with a flat surface 23A that extends parallel to the axis O.
In addition, a coolant supply hole is formed in the shank portion 21 so as to penetrate from the rear end side to the front end side of the shank portion 21.

  The front end side of the shank portion 21 has a smaller diameter than the rear end side, and a V-shaped groove 24 whose central portion is recessed toward the rear end side of the shank portion 21 is formed on the front end surface 41A of the bottom portion of the groove. Is perpendicular to the axis O, and a V-shaped bisector is formed on the axis O. Here, the angle formed by the two side wall surfaces 27 of the V-shaped groove 24 is in the range of 60 ° to 120 °, and is set to 90 ° in the present embodiment. The coolant supply hole is opened at the groove bottom of the V-shaped groove 24.

The blade edge portion 22 also has a substantially cylindrical shape centered on the axis O, and the rear end surface thereof has a convex V-shaped convex shape that can be fitted into a V-shaped groove 24 formed on the front end surface of the shank portion 21. The portion 25 is formed so that the V-shaped ridge line is also orthogonal to the axis O and the V-shaped bisector is positioned on the axis O.
The tip of the cutting edge portion 22 has a larger diameter than the portion where the convex portion 25 is formed, and a plurality of chip discharge grooves 26 extending toward the rear end side in the axis O direction are formed on the outer peripheral portion thereof. These are arranged rotationally symmetrically by a predetermined angle with respect to the axis O at equal intervals in the circumferential direction. In the present embodiment, as shown in FIG. 4, the three chip discharge grooves 26 are arranged rotationally symmetrical by 120 ° with respect to the axis O.

A cutting edge 29 is formed at the intersecting ridge line portion between the wall surface 27 facing the front side in the tool rotation direction T of the chip discharge groove 26 and the outer peripheral surface 28 connected to the rear side in the tool rotation direction T, and the front side in the tool rotation direction T. A biting portion 29 </ b> A continuous with the cutting blade 29 is formed on the radially outer side of the intersecting ridge line portion between the wall surface 27 facing the tip and the tip end surface of the blade edge portion 22.
By forming the cutting edge 29 in this way, the wall surface 27 facing the front side in the tool rotation direction T of the chip discharge groove 26 is a rake face, and the outer peripheral surface 28 connected to the rear side in the tool rotation direction T is a flank face. . In addition, the rotation locus | trajectory which this cutting edge 29 makes around the axis line O is made into the cylindrical surface shape centering on the axis line O in this embodiment.

  Here, the chip discharge groove 26 has a U-shaped cross section as shown in FIG. 4, that is, a wall surface 27 facing the front side in the tool rotation direction T of the chip discharge groove 26 and a wall surface facing the rear side in the tool rotation direction T. Is formed so as to face substantially parallel via a concave arc-shaped groove bottom, and a wall surface 27 facing the front side in the tool rotation direction T forming a rake face is substantially the outer shape of the cutting edge portion 22. The cross section is formed so as to extend along the radial direction of the circle.

  In addition, a guide portion 30 is formed on the outer peripheral surface 28 that is continuous to the rear side of the chip discharge groove 26 in the tool rotation direction T so as to be in sliding contact with the inner wall surface of the machining hole. The guide portion 30 is formed with an oil groove portion 32 that recedes toward the radially inner side of the blade edge portion 22. In the present embodiment, the bottom of the oil groove portion 32 has an arc shape centering on the axis O that protrudes outward in a cross section orthogonal to the axis O.

  Therefore, the outer peripheral surface 28 includes a first guide portion 31 continuous to the tool rotation direction T rear side of the cutting edge 29, an oil groove portion 32 continuous to the tool rotation direction T rear side of the first guide portion 31, and an oil groove portion. Thus, a second guide portion 33 is formed which continues to the rear side of the tool rotation direction T. Further, the first and second guide portions 31 and 33 have an arc shape having a radius equal to the outer diameter of the cutting edge 29 in a cross section perpendicular to the axis O.

In the cross section along the axis O, the oil groove portion 32 opens toward the front end side in the axis O direction as shown in FIG. 3, and the rear end side in the axis O direction as shown in FIG. It is rounded up outward. More specifically, the oil groove 32 extends from the front end side in the direction of the axis O toward the rear end side of the axis O with a constant groove depth, and the groove depth increases toward the rear end side of the axis O at the rear end portion of the axis O. Is configured to gradually become shallower.
In the present embodiment, since the three chip discharge grooves 26 are formed and the guide portions 30 are respectively formed on the rear sides of the chip discharge grooves 26 in the tool rotation direction T, the cutting edge portion 22 has three pieces. The oil groove 32 is provided.

  Further, the blade edge portion 22 is formed with a blind hole-like communication hole 34 extending along the axis O and opened in the convex portion 25, from the communication hole 34 toward the bottom of each oil groove portion 32. An extended coolant discharge hole 35 is formed. Here, in the reamer 20 according to the present embodiment, since the coolant discharge holes 35 are opened in the three oil groove portions 32, respectively, three coolant discharge holes 35A, 35B, and 35C are formed. .

  And these three coolant discharge hole 35A, 35B, 35C is arrange | positioned in the position where the axis line O direction differs, as shown in FIG.2 and FIG.3. More specifically, the coolant discharge holes 35A, 35B, and 35C are formed so that the oil gradually moves outward in the radial direction of the cutting edge portion 22 from the outer peripheral wall of the insertion hole 34 extending along the axis O toward the tip end side in the axis O direction. The grooves 32 are formed at equal intervals in the circumferential direction so as to open at the center in the circumferential direction, and the rotation trajectories around the axis O of the three coolant discharge holes 35A, 35B, 35C are in the direction of the axis O. Are configured to be parallel to each other at substantially equal intervals.

This reamer 20 is used by being mounted on a cutting tool 40 shown in FIG. The cutting tool 40 includes a multi-stage cylindrical tool body 41 that rotates about the axis M, and a cutting insert 42 is provided on the outer periphery of the tip end portion of the tool body 41.
A mounting hole 43 extending along the axis M is formed in the distal end surface 41A of the tool body 41. A coolant hole 45 into which the position adjusting bolt 44 is inserted is provided on the rear end side of the mounting hole 43, and the coolant hole 45 opens to a mounting portion 46 provided on the rear end side of the tool body 41. , Communicated with the mounting hole 43.
Further, the tool body 41 is formed with a screw hole 47 that is open on the side surface of the tool body 41 and communicates with the mounting hole 43, and a clamp screw 48 is screwed into the screw hole 47.

  The reamer 20 is inserted into a mounting hole 43 formed in the front end surface 41A of the tool body 41, the rear end surface of the shank portion 21 is brought into contact with the front end surface 41A of the position adjusting bolt 44, and the flat surface of the shank portion 21. 23A is disposed so that the screw hole 47 of the tool body 41 is provided and the axis O of the reamer 20 and the axis M of the tool body 41 coincide. Then, the reamer 20 is fixed to the tool body 41 by screwing the clamp screw 48 screwed into the screw hole 47 of the tool body 41 and pressing the flat surface 23A.

  The cutting tool 40 to which the reamer 20 is mounted in this manner is attached to the spindle end of the machine tool via the attachment portion 46, and after adjusting the position of the reamer 20 in the direction of the axis M, the axis M (axis O). The reamer 20 is inserted into, for example, a stem guide hole (a pilot hole formed in the material to be cut), and the inner wall surface of the stem guide hole is passed through the inner wall surface of the stem guide hole. It cuts and forms the processing hole of a predetermined internal diameter.

  When cutting with the reamer 20, the cutting fluid is supplied from the machine tool to the coolant hole 45 of the tool body 41 through a pipe. The cutting fluid supplied to the coolant hole 45 is supplied to the blade edge portion 22 through a coolant supply hole (not shown) formed in the shank portion 21 of the reamer 20, and through the communication hole 34 formed in the blade edge portion 22. The oil is discharged from the coolant discharge hole 34 opened in the bottom surface of the oil groove portion 32.

According to the reamer 20 according to the present embodiment, the guide portions 30 (first and second guide portions 31 and 33) that are in sliding contact with the inner wall of the machining hole are respectively located on the rear side in the tool rotation direction T of the plurality of chip discharge grooves 26. Since it is provided, it is possible to prevent a shake when the reamer 20 is rotated at a high speed in the processed hole, and the processed hole can be accurately formed.
Further, an oil groove portion 32 that is recessed toward the radially inner side of the blade edge portion 22 is formed in the guide portion 30, and a coolant discharge hole 34 that is communicated with the coolant supply hole is opened at the bottom portion of the oil groove portion 32. Therefore, the cutting oil is supplied to the guide portions 30 (first and second guide portions 31 and 33) that are in sliding contact with the inner wall surface 27 of the machining hole to improve the lubrication and effectively reduce the rotational torque of the reamer 20. can do.

Further, since the plurality of coolant discharge holes 34 respectively opened in the oil groove portion 32 are arranged at different positions in the direction of the axis O, the portion where the blade edge portion 22 is drilled to form the coolant discharge hole 34 is the axis line. It will vary in the O direction, the strength reduction of the blade edge portion 22 can be prevented, the breakage of the reamer 20 can be suppressed, and the life can be extended.
Further, an oil groove portion 32 that is recessed toward the radially inner side of the blade edge portion 22 is formed in the guide portion 30, and a first guide portion 31 that continues to the rear side in the tool rotation direction T of the cutting blade 29 on the outer peripheral surface 28, Since the oil groove portion 32 and the second guide portion 33 are formed, the frictional resistance between the outer peripheral surface 28 of the cutting edge portion 22 and the machining hole inner wall surface 27 does not become too large, and an increase in rotational torque can be prevented. .

  Further, the oil groove portion 32 is configured to open toward the front end side in the axis O direction, and the rear end side portion in the axis O direction is configured to be rounded up toward the radially outer side of the blade edge portion 22. Is reliably discharged toward the front end side in the direction of the axis O, and in the vicinity of the cutting edge 29, the guide portion 30 (first and second guide portions 31, 33) and the inner wall surface of the machining hole are well lubricated. Thus, the reamer 20 can be prevented from being shaken to perform cutting with high dimensional accuracy, and an increase in the rotational torque of the reamer 20 can be suppressed. In particular, when the pilot hole is a through hole such as a stem guide hole, chips generated by the cutting blade 29 are surely discharged from the opening of the through hole to prevent deterioration in machining accuracy due to chip biting or the like. be able to.

Further, in the present embodiment, since the bottom of the oil groove 32 is formed in an arc shape with the axis O as the center, the portion where the blade edge 22 is cut out can be reduced, and the rigidity of the reamer 20 is improved. Can be made.
Further, the chip discharge groove 26 is formed in a U-shaped cross section, and is not greatly opened outward in the radial direction, and there are few notches, so the rigidity of the reamer 20 is further improved and rotated at high speed. It is possible to prevent run-out.

As mentioned above, although the reamer which is embodiment of this invention was demonstrated, 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, the bottom portion of the oil groove portion has been described as being formed in an arc shape centering on the axis O, but is not limited thereto, and may be formed so as to protrude radially inward. .

Furthermore, although the chip discharge groove has been described as being formed so as to extend along the axis O, the present invention is not limited to this, and the tool rotation direction T is directed toward the front side as it moves toward the rear end side of the axis O. You may form so that it may be twisted and may be formed so that it may twist toward the tool rotation direction T back side.
Furthermore, although the reamer has been described as being used by being mounted on the cutting tool shown in FIG. 5, it may be used by being mounted on another cutting tool or an adapter.

It is a side view of the reamer which is an embodiment of the present invention. FIG. 2 is an enlarged side view of the reamer shown in FIG. 1. It is side surface sectional drawing of a reamer shown in FIG. It is a front view of the reamer shown in FIG. FIG. 4 is a side view of the reamer shown in FIG. 3. It is a side view of the conventional reamer. FIG. 7 is a front view of the reamer shown in FIG. 6.

Explanation of symbols

20 Reamer (Drilling tool)
21 Shank part 22 Cutting edge part 26 Chip discharge groove 27 Wall face 28 facing the front side in the tool rotation direction T Outer peripheral surface 29 Cutting edge 30 Guide part 31 First guide part 32 Oil groove part 33 Second land part 35 Coolant discharge hole

Claims (2)

A hole machining tool that is inserted into a prepared hole formed in a work material in advance and forms a processed hole by cutting the inner wall surface of the prepared hole,
Having a shank portion rotated around an axis and having a coolant supply hole formed therein, and a cutting edge portion provided with a cutting edge;
A plurality of chip discharge grooves extending from the front end side toward the rear end side are formed on the outer peripheral portion of the blade edge portion, and a wall surface facing the front side in the tool rotation direction of the chip discharge groove and an outer peripheral surface of the blade edge portion. The cutting edge is formed in the intersecting ridge line part,
A guide portion that is in sliding contact with the inner wall surface of the machining hole is provided at the rear of each chip discharge groove in the tool rotation direction, and the guide portion retreats inward in the radial direction of the blade edge portion, and An oil groove is provided with a coolant discharge hole communicating with the coolant supply hole.
These coolant discharge holes are arranged at different positions in the axial direction.   2. The hole according to claim 1, wherein the oil groove portion is opened toward the front end side in the axial direction, and the rear end side in the axial direction is rounded up toward a radially outer side of the cutting edge portion. Processing tool.

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