JP4779546B2 - Drilling tool - Google Patents

Description

  The present invention relates to a hole machining tool that is inserted into a prepared hole formed in a workpiece, and cuts the inner wall surface of the prepared hole.

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

An example of a conventional reamer is shown in FIGS. The reamer 1 includes a shank portion 2 having a long cylindrical shape, and a blade edge portion 3 disposed on the tip side of the shank portion 2.
The shank portion 2 has a substantially multi-stage cylindrical shape, and a mounting portion 4 for mounting the reamer 1 on a cutting tool is provided on the rear end side. On the other hand, a V-shaped groove 5 having a central portion recessed toward the rear end side of the shank portion 2 is formed on the front end surface of the shank portion 2.
Further, a coolant supply hole (not shown) is formed in the shank portion 2 so as to penetrate from the front end side to the rear end side of the shank portion 2, and is opened in the V-shaped groove 5.

The blade edge portion 3 has a substantially cylindrical shape, and a convex portion 6 that can be fitted into a V-shaped groove 5 formed on the front end surface of the shank portion 2 is formed on the rear end surface thereof.
As shown in FIG. 9, on the outer periphery of the tip of the blade edge portion 3, there are six chip discharge grooves 7 that extend toward the rear end side in the axis O direction and twist at a predetermined angle toward the front side in the tool rotation direction T. They are arranged in 60-degree rotational symmetry with respect to the axis O at equal intervals in the circumferential direction.

A cutting edge 10 is formed at the intersecting ridge line portion of the wall surface 8 facing the front side of the tool rotation direction T of the chip discharge groove 7 and the outer peripheral surface 9 connected to the rear side of the tool rotation direction T. By forming the cutting edge 10 in this manner, the wall surface 8 facing the front side in the tool rotation direction T of the chip discharge groove 7 is a rake face, and the outer peripheral surface 9 connected to the rear side in the tool rotation direction T is a flank face. .
As shown in FIG. 9, the chip discharge groove 7 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 8 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 3.

  Further, in the vicinity of the axis O of the blade edge portion 3, there are formed communication holes (not shown) extending along the axis O and opened on the rear end side (convex portion). A discharge hole 11 extending in the chip discharge groove 7 and opened at the bottom of the groove is provided.

At this time, since the chip discharge groove 7 is formed to be twisted forward in the tool rotation direction T, the chips generated by the cutting blade 11 are guided toward the tip side of the reamer 1. Further, when the cutting fluid is discharged from the discharge hole 11 through the coolant supply hole and the communication hole, the chips are discharged toward the tip of the reamer 1 so as to be flowed by the cutting fluid flowing through the chip discharge groove 7. The
JP 2000-263328 A JP 2002-59313 A

By the way, in the conventional reamer shown in FIGS. 9 and 10, since the chips are discharged toward the reamer tip side, the chip discharge grooves have a V-shaped cross section even though they do not pass through the chip discharge grooves. Therefore, it is formed so as to open toward the outside in the radial direction. However, if the chip discharge groove is formed in such a way that the cutting edge is greatly cut out, the rigidity of this reamer is reduced, and the reamer is shaken when the reamer is rotated at a high speed, so that the machining hole is accurately There was a problem that it could not be molded well.
In addition, the reamer may break due to the cutting resistance at the time of cutting, for example, starting from the portion where the discharge hole is formed.

  The present invention has been made in view of the above-described circumstances, and by ensuring the rigidity of the reamer, it is possible to prevent a shake during high-speed rotation and form a machined hole with high accuracy, and break due to cutting resistance. An object of the present invention is to provide a drilling tool capable of suppressing the above and extending the life.

In order to solve the above-mentioned problems, the present invention is a hole machining tool for cutting an inner wall surface of a prepared hole that is inserted into a prepared hole formed in advance in a workpiece, and is a shank portion that rotates about an axis. A cutting edge having a cutting edge is provided on the front end side of the shank portion, and a chip discharge groove extending from the front end side toward the rear end side is formed on the outer peripheral portion of the cutting edge portion. wherein the intersecting edge line region of the outer peripheral surface of the wall and the edge portion facing the tool rotation direction front side of the chip discharge groove cutting edge is formed, a cross-section perpendicular to the axis of the chip discharge groove is formed in a U-shape The outer peripheral surface includes a first land portion formed so as to be continuous with the cutting edge, a relief portion that is continuous with the rear side in the tool rotation direction of the first land and is retreated inward in the radial direction, A second land portion formed so as to be connected to the rear side in the tool rotation direction, Has a discharge hole for discharging the cutting fluid, and the discharge hole is opened from the front end of the cutting edge part to the rear end side of 2/3 of the axial length of the cutting edge part. It is characterized in that there.

  The chip discharge groove has a U-shaped cross section, that is, the wall surface facing the tool rotation direction front side of the chip discharge groove and the wall surface facing the tool rotation direction rear side are substantially parallel via a groove bottom such as a concave arc in the cross section. For example, when the same groove depth as that of the above-described conventional reamer V-shaped chip discharge groove and the same radius of the concave arc formed by the groove bottom is formed. The portion to be cut out is reduced, and the rigidity of the drilling tool can be ensured. Therefore, the machined hole can be formed with high accuracy by preventing runout during high-speed rotation, and the life can be extended by suppressing breakage due to cutting resistance.

  In addition, since the cross-sectional area of the chip discharge groove is reduced, when the cutting fluid is discharged from the discharge hole opened at the bottom of the chip discharge groove, the flow rate of the cutting oil passing through the chip discharge groove is increased, Chips generated by the cutting blade can be reliably discharged, for example, toward the tip of the hole machining tool. Therefore, even if the cross-sectional area of the chip discharge groove is reduced by discharging the chips in the tip direction in this way, the chips are not clogged in the chip discharge groove, and the machining with this drilling tool is performed smoothly. be able to.

Here, a first land portion formed on the outer peripheral surface so as to be continuous with the cutting edge, a relief portion that is continuous with the rear side in the tool rotation direction of the first land and is retreated inward in the radial direction, Since the second land portion formed so as to be connected to the rear side in the tool rotation direction is provided , the portion that slides with the processing hole can be reduced, and the cutting resistance of the hole processing tool can be reduced. . Further, since the first land portion and the second land portion are formed, the processing hole and the first and second land portions can slide to finish the inner wall surface of the processing hole smoothly. Moreover, these 1st, 2nd land parts play the role of a guide, rotation of this drilling tool is stabilized, and a process hole can be shape | molded accurately.

Further, a discharge hole for discharging the cutting fluid is provided in the escape portion, and the opening portion of the discharge hole is arranged on the rear end side from the front end of the cutting edge portion to 2/3 of the axial length of the cutting edge portion. Therefore , the cutting fluid can be supplied at a large flow rate from the escape portion toward the tip of the blade tip, reducing the sliding friction by the first and second land portions, and further reducing the cutting resistance. The chips generated by the above can be discharged more reliably toward the tip end side of the blade edge part.

  As described above, according to the present invention, by ensuring the rigidity of the reamer, it is possible to accurately form a machined hole by preventing runout during high-speed rotation, and to extend the life by suppressing breakage due to cutting resistance. It is possible to provide a drilling tool that can be used.

The present invention belongs to a group of inventions including a plurality of inventions described below. Hereinafter, the first and second embodiments will be described as embodiments of the invention group. The embodiment corresponds to the invention described in the claims of the present applicant.
Below, the drilling tool which is the 1st Embodiment of this invention is demonstrated with reference to attached drawing. 1 and 2 show a reamer as a drilling tool according to an embodiment of the present invention. FIG. 3 shows a cutting tool to which this reamer is attached.
The reamer 21 includes a shank portion 22 having a long cylindrical shape, and a cutting edge portion 23 disposed on the distal end side (lower side in FIG. 2) of the shank portion 22.

The shank portion 22 has a substantially multi-stage cylindrical shape centered on the axis O, and a mounting portion 24 for mounting the reamer 21 to the cutting tool 41 is provided on the rear end side (upper side in FIG. 2). ing. The mounting portion 24 is provided with a flat surface 24A that extends parallel to the axis O.
The front end side of the shank portion 22 has a smaller diameter than the rear end side, and a V-shaped groove 25 whose center portion is recessed toward the rear end side of the shank portion 22 on the front end surface has a groove bottom portion at the axis O. And a V-shaped bisector is formed on the axis O. Here, the angle formed by the two side wall surfaces of the V-shaped groove 25 is in the range of 60 ° to 120 °, and is set to 90 ° in the present embodiment.
In addition, a coolant supply hole is formed in the shank portion 22 so as to penetrate from the front end side to the rear end side of the shank portion 22, and is open to the V-shaped groove 25.

The blade edge portion 23 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 25 formed on the front end surface of the shank portion 22. The portion 26 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.
A plurality of chip discharge grooves 27 that extend toward the rear end side in the axis O direction and are twisted at a predetermined twist angle (15 ° in the present embodiment) toward the front side in the tool rotation direction T are formed on the outer periphery of the tip of the cutting edge portion 23. These are arranged rotationally symmetrically by a predetermined angle with respect to the axis O at equal intervals in the circumferential direction. In the first embodiment, as shown in FIG. 1, the six chip discharge grooves 27 are arranged rotationally symmetrically by 60 ° with respect to the axis O.

A cutting edge 30 is formed at the crossing ridge line portion between the wall surface 28 of the chip discharge groove 27 facing the front side in the tool rotation direction T and the outer peripheral surface 29 connected to the rear side in the tool rotation direction T, and the front side in the tool rotation direction T. A biting portion 30 a that is continuous with the cutting blade 30 is formed on the outer peripheral side of the intersecting ridge line portion between the wall surface 28 facing the side and the tip surface of the blade edge portion 23.
By forming the cutting edge 30 in this manner, the wall surface 28 facing the front side in the tool rotation direction T of the chip discharge groove 27 is a rake face, and the outer peripheral surface 29 connected to the rear side in the tool rotation direction T is a flank face. . The cutting blade 30 is spirally twisted at a predetermined twist angle (15 ° in the present embodiment) around the axis O in the tool rotation direction T as it goes to the rear end side in the same manner as the chip discharge groove 27. Is formed. The rotation locus made by the cutting edge 30 about the axis O is a cylindrical surface centered on the axis O in the present embodiment.

  Here, the chip discharge groove 27 has a U-shaped cross section as shown in FIG. 1, that is, a wall surface 28 facing the tool rotation direction T front side of the chip discharge groove 27 and a wall surface facing the tool rotation direction rear side are on the axis O. In the vertical cross section, the wall surface 28 is formed so as to be opposed substantially parallel to each other through the concave arc-shaped groove bottom, and the wall surface 28 facing the front side in the tool rotation direction T forming the rake face is a cross section of the outline of the cutting edge portion 23. Is formed so as to extend along the radial direction of the circle formed by.

  Further, four outer peripheral surfaces 29 among the six outer peripheral surfaces formed as flank surfaces are formed in an arc shape having a radius equal to the outer diameter of the cutting blade 30 in a cross section perpendicular to the axis O in a portion continuous to the cutting blade 30. The land portion 31 is formed, and on the rear side of the land portion 31 in the tool rotation direction T, an escape portion 32 is formed that is retracted radially inward. In the present embodiment, the relief portion 32 is formed in a cross section perpendicular to the axis O so as to form a convex arc shape having a radius slightly smaller than the outer diameter of the cutting edge 30. Further, the remaining two outer peripheral surfaces 29 are not formed with escape portions 32, and the entire outer peripheral surface 29 is a land portion 31.

  Further, the blade edge portion 23 is formed with a communication hole (not shown) that extends along the axis O and opens in the convex portion 26, and extends from the communication hole toward each chip discharge groove 27. A discharge hole 33 opened at the bottom of the groove is provided.

This reamer 21 is used by being mounted on a cutting tool 41 shown in FIG. The cutting tool 41 has a multi-stage cylindrical tool body 42 that is rotated about the axis M, and a cutting insert 43 is provided on the outer periphery of the tip of the tool body 42.
A mounting hole 44 extending along the axis M is formed in the distal end surface 42A of the tool body 42. A coolant hole 46 into which a position adjusting bolt 45 is inserted is provided so as to communicate with the rear end side of the mounting hole 44, and the coolant hole 46 is opened in a mounting portion 47 provided on the rear end side of the tool body 42. Has been.
Further, a screw hole 48 is formed in the side surface of the tool main body 42 so as to communicate with the mounting hole 44, and a clamp screw 49 is screwed thereto.

  The reamer 21 is inserted into a mounting hole 44 formed in the front end surface 42A of the tool body 42, the rear end surface of the shank portion 22 is brought into contact with the front end surface of the position adjusting bolt 45, and the flat surface 24A of the shank portion 22 is used. Is arranged so that the screw hole 48 of the tool main body 42 is provided and the axis O of the reamer 21 and the axis M of the tool main body 42 coincide with each other. The reamer 21 is fixed to the tool body 42 by screwing a clamp screw 49 screwed into the screw hole 48 of the tool body 42 and pressing the flat surface 24A.

  The cutting tool 41 to which the reamer 21 is mounted in this manner is attached to the spindle end of the machine tool via the attachment portion 47, and after adjusting the position of the reamer 21 in the direction of the axis M, the axis around the axis M (axis O). And the reamer 21 is inserted into, for example, a stem guide hole (a pilot hole formed in the workpiece), and the inner wall surface of the stem guide hole is cut. Thus, a processing hole having a predetermined inner diameter is formed.

  When cutting with the reamer 21, a cutting fluid is supplied from the machine tool to the coolant hole 46 of the tool body 42 through a pipe. The cutting fluid supplied to the coolant hole 46 is supplied to the blade edge portion 23 through the coolant supply hole formed in the shank portion 22 of the reamer 21, and the chip discharge groove through the communication hole and the discharge hole 33 formed in the blade edge portion 23. 27 is discharged from the bottom of the groove 27 toward the inner wall surface of the pilot hole.

  Chips generated when the inner wall surface of the pilot hole is cut are formed so that the chip discharge grooves 27 are twisted forward in the tool rotation direction T, and therefore are guided toward the tip side of the reamer 21. become. Further, when the cutting fluid is discharged from the discharge hole 33 through the coolant supply hole and the communication hole, the chips are discharged toward the front end side of the reamer 21 so that the cutting fluid flows.

  According to the reamer 21 according to the first embodiment, the chip discharge groove 27 is formed in a U-shaped cross section, and is not greatly opened toward the outside in the radial direction. The rigidity is ensured. Accordingly, it is possible to prevent the shake when the reamer 21 is rotated at a high speed and form the processed hole with high accuracy. Moreover, it is possible to prevent the reamer 21 from being broken by cutting resistance and to extend the life of the reamer 21.

  Further, since the cross-sectional area of the chip discharge groove 27 is reduced, when the cutting fluid is discharged from the discharge hole 33 opened in the groove bottom portion of the chip discharge groove 27, the cutting oil passing through the chip discharge groove 27 is reduced. The flow velocity is increased, and the chips generated by the cutting blade 30 can be reliably discharged toward the tip of the reamer 21. Therefore, since the chips do not pass through the chip discharge groove 27, the chips can be reliably discharged even if the cross-sectional area of the chip discharge groove 27 is reduced, and the processing with the reamer 21 can be performed smoothly. it can.

  Further, land portions 31 and relief portions 32 are formed on four outer peripheral surfaces 29 of the six outer peripheral surfaces 29 that are connected to the respective cutting blades 30 to form flank surfaces, and the remaining two outer peripheral surfaces 29 are entirely landed. Since the reamer 21 reduces the cutting resistance when machining the prepared hole and the land portion 31 stabilizes the rotation of the reamer 21, the machined hole can be formed with higher accuracy. it can. Further, the machined hole inner wall surface after cutting and the land portion 31 slide, so that the machined hole inner wall surface can be burnished and finished smoothly.

Next, the reamer 21 according to the second embodiment will be described with reference to FIGS. 4 and 5. In addition, the same code | symbol is attached | subjected to the member same as 1st Embodiment, and description is abbreviate | omitted.
As shown in FIG. 4, the reamer 21 according to the second embodiment includes three strip discharge grooves 27 having a V-shaped cross section, and the chip discharge grooves 27 are rotationally symmetrical by 120 ° with respect to the axis O. This is a three-blade reamer 21 in which a cutting edge 30 is formed on the outer peripheral side ridge portion of the wall surface 28 facing the front side in the tool rotation direction T of the chip discharge groove 27.

  An outer peripheral surface 29 that is continuous with the cutting edge 30 and forms a flank face is connected to a first land portion 34 that is formed to be continuous with the cutting edge 30 and to the rear side in the tool rotation direction T of the first land. A retracted escape portion 32 and a second land portion 35 formed so as to continue to the rear side of the escape portion 32 in the tool rotation direction T are provided. The first land portion 34 and the second land portion 35 are formed in an arc shape having the same radius with the axis O as the center. In addition, the escape portion 32 is formed in an R-groove shape that is wider than the chip discharge groove 27 and has a shallow groove depth and protrudes radially inward in a cross section perpendicular to the axis O.

  Furthermore, in the first embodiment described above, the chip discharge groove 27 and the escape portion 32 are formed over the entire length of the blade edge portion 23, whereas in the second embodiment, the escape portion 32 is the blade edge portion 23. On the other hand, the rear end of the chip discharge groove 27 is rounded up from the rear end of the blade edge portion 23.

Further, a discharge hole 33 opened from a communication hole (not shown) formed in the blade edge portion 23 toward the groove bottom portion of each chip discharge groove 27 is provided, and the groove of the R groove formed by the escape portion 32 is provided. A discharge hole 36 opened toward the bottom is provided.
The opening of the discharge hole 36 is disposed on the rear end side of the cutting edge 23 from the front end of the cutting edge 23 with respect to 2/3 L, where L is the length in the axial direction of the cutting edge 23.

According to the reamer 21 according to the second embodiment, since the cross section of the chip discharge groove 27 is U-shaped, the same effect as the reamer 21 according to the first embodiment can be obtained.
In addition, since the relief portion 32 is formed on the outer peripheral surface 29 that forms the relief surface, the portion that slides with the inner wall surface of the processed hole can be adjusted, and the cutting resistance of the reamer 21 can be reduced. Further, since the first land portion 34 and the second land portion 35 are formed, the machining hole and the first and second land portions 34 and 35 slide to finish the inner wall surface of the machining hole smoothly. Can do. In addition, the first and second land portions 34 and 35 serve as guides, and the rotation of the reamer 21 is stabilized, so that the processed hole can be accurately formed.

Further, the cutting oil is supplied not only from the discharge hole 33 opened at the groove bottom of the chip discharge groove 27 but also from the discharge hole 36 opened at the groove bottom of the R groove formed by the escape portion 32. It is possible to reliably discharge chips.
Furthermore, since the discharge hole 36 is opened from the front end of the blade edge portion 23 to the rear end side more than 2/3 L when the length of the blade edge portion 23 in the axial direction is L, the clearance portion 32 extends from the escape portion 32 to the blade edge portion. 23, the flow rate of the cutting fluid discharged toward the tip end side can be increased, and the chips generated by the cutting blade 30 can be discharged more reliably toward the tip end side of the reamer 21.

As mentioned above, although the reamer 21 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, as shown in FIG. 6, the relief portion 32 provided on the outer peripheral surface 29 connected to the cutting edge 30 may be formed in an arc shape that is convex outward in the radial direction and centered on the axis O. By forming the escape portion 32 in this way, the portion where the blade edge portion 23 is cut out can be further reduced, and the rigidity of the reamer 21 can be further improved.

  Moreover, as shown in FIG. 7, the relief part 32 provided in the outer peripheral surface 29 connected to the cutting blade 30 may be formed in a flat shape, and the cross section of the blade edge part 23 may be formed in a substantially equilateral triangle shape. . In the reamer 21 configured as described above, a part of the circle formed by the outer shape of the cutting edge portion 23 can be cut off linearly in the cross section to provide the escape portion 32. Therefore, the reamer 21 can be manufactured at low cost. Can do.

  Further, as shown in FIG. 8, the relief portion 32 provided on the outer peripheral surface 29 connected to the cutting edge 30 has a flat surface portion 37 and a central portion of the flat surface portion 37 projecting radially inward. You may comprise by the R groove part 38 notched by the R groove shape used as this. With such a configuration, the escape portion 32 can be easily provided, and the cutting fluid can be reliably supplied toward the distal end side through the R groove portion 38.

  Further, the chip discharge groove 27 has been described so as to be twisted toward the front side of the tool rotation direction T as it goes toward the rear end side of the reamer 21, but the present invention is not limited to this, and the tool rotation direction is not limited thereto. You may form so that it may twist toward T back side, or you may form in the linear form without twist. In such cases, the chips generated by the cutting blade 30 are not guided to the tip of the reamer 21, but the cutting fluid flows through the chip discharge groove 27 toward the tip of the reamer 21 at a high flow rate. The chips can be discharged to the tip side of the reamer 21.

  Furthermore, although the reamer 21 has been described as being used by being mounted on the cutting tool 41 shown in FIG. 3, it may be used by being mounted on another cutting tool or an adapter.

It is a front view of the reamer which is the 1st Embodiment of this invention. It is a side view of the reamer shown in FIG. It is a front view of the reamer which is the 2nd Embodiment of this invention. It is a front view of the reamer which is the 2nd Embodiment of this invention. FIG. 4 is a side view of the reamer shown in FIG. 3. It is a front view of the reamer which is other embodiment of this invention. It is a front view of the reamer which is other embodiment of this invention. It is a front view of the reamer which is other embodiment of this invention. It is a front view of the conventional reamer. FIG. 9 is a side view of the reamer shown in FIG. 8.

Explanation of symbols

21 Reamer (Drilling tool)
22 Shank portion 23 Cutting edge portion 27 Chip discharge groove 28 Wall surface 29 facing the front side of the tool rotation direction T Outer peripheral surface 30 Cutting blade 31 Land portion 32 Escape portion 34 First land portion 35 Second land portion 36 Discharge hole

Claims (1)

A hole machining tool that is inserted into a prepared hole formed in advance in a workpiece and cuts the inner wall surface of the prepared hole,
It has a shank portion that rotates around the axis, and a tip portion having a cutting edge is provided on the tip side of the shank portion,
A chip discharge groove extending from the front end side toward the rear end side is formed on the outer peripheral portion of the cutting edge portion, and a cross ridge line between a wall surface facing the front side in the tool rotation direction of the chip discharge groove and the outer peripheral surface of the cutting edge portion. The cutting blade is formed in the part,
A cross section perpendicular to the axis of the chip discharge groove is formed in a U shape,
The outer peripheral surface includes a first land portion formed so as to be continuous with the cutting edge, a relief portion that is continuous with the rear side in the tool rotation direction of the first land and is retreated inward in the radial direction, and the tool rotation of the relief portion. A second land portion formed so as to continue to the rear side in the direction,
A discharge hole for discharging the cutting fluid is opened in the escape portion, and the discharge hole is located on the rear end side from the front end of the cutting edge portion to 2/3 of the axial length of the cutting edge portion. A drilling tool characterized by being opened.

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