JP2009050994A - Hole working tool - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a hole working tool which improves working accuracy while ensuring guide action by a guide bush of a cutting tool at the maximum and reducing a burnish torque due to the guide bush. <P>SOLUTION: The hole working tool has a tool body 12 rotated around an axis line O, which has a cutting blade 14 on the tip end thereof, and a shank 13 on the rear end, and is mounted into the cutting tool 40 through the guide bush 41 for guiding the tool body 12. The tool body 12 is inserted into a prepared hole formed beforehand on a member to be cut, and cuts the internal wall of the prepared hole to form a hole. On the rear end of the cutting blade 14, there are provided: a plurality of circular arc shaped tangent circumferential surfaces 31 disposed with intervals on a circumference of the outer periphery which slides with the internal wall surface 41a of the guide bush 41 in a cross section vertical to the axis line O; and a guided section 30 which is disposed between the tangent circumference surfaces 31 and has a clearance face 32 formed to bend inward of the circumference. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a drilling tool such as a reamer that is inserted into a prepared hole formed in a work material in advance and cuts an inner wall surface of the prepared hole to form a processed hole having a predetermined inner diameter.

  As this type of drilling tool, for example, a long cylindrical reamer as described in Patent Document 1 or Patent Document 2 is known. This reamer has a long shaft-shaped tool body that is rotated around an axis, a cutting blade portion is provided on the tip side of the tool body, and a rear end side is a shank portion. In addition, a chip discharge groove extending toward the rear end side in the axial direction is formed on the outer periphery of the cutting edge portion, and the outer peripheral cutting edge is formed on the outer peripheral side ridge portion of the wall surface facing the front side in the tool rotation direction of the chip discharge groove. In addition to being formed, a tip cutting edge is formed on a side ridge portion on the outer peripheral side of the tip surface of the previous wall surface.

Such a reamer is used by attaching the tool body to a cutting tool via a cylindrical guide bush, and this cutting tool is attached to the main end shaft of a machine tool or the like and rotates around the axis. At the same time, the tool body is guided to the inner peripheral wall surface of the guide bush and is sent to the tip end in the axial direction, and inserted into the pilot hole of the workpiece, for example, the stem guide hole of the valve in the engine cylinder head. Then, the inner wall surface of the prepared hole is cut to form a processed hole having a predetermined inner diameter.
JP 2000-263328 A JP 2007-098517 A

  By the way, in the above-described reamer, the outer peripheral surface of the cutting edge portion rear end side of the tool body mounted on the cutting tool can be slidably contacted with the inner peripheral wall surface of the guide bush over the entire periphery. The guide to the tip end in the axial direction of the tool body is secured, and machining accuracy such as roundness and straightness of the machining hole is improved. However, since a slight clearance is provided between the outer peripheral surface of the tool body and the inner peripheral wall surface of the guide bush from the rear end to the shank portion of the cutting blade portion, the rear end side of the cutting blade portion extends from the guide bush. When it comes out, the axis of the cutting tool and the axis of the tool body are slightly displaced within the clearance range, and the cutting edge of the cutting edge of the tool body and the cutting edge of the tool are touched during machining. Therefore, there is a problem that the guide action by the guide bush cannot be fully utilized, and the original high-precision cutting of the drilling tool for precisely finishing the prepared hole cannot be performed.

  On the other hand, if the portion slidably in contact with the inner peripheral wall surface of the guide bush on the tip end side of the cutting edge is lengthened, the burnish torque due to the slidable contact with the guide bush becomes too large, and the tool body may be broken.

  The present invention has been made in view of such problems, and can improve the machining accuracy and tool life by reducing the vanishing torque by the guide bush while ensuring the maximum guide action by the guide bush. An object of the present invention is to provide a drilling tool that can perform the above-described process.

In order to solve the above problems, the present invention proposes the following means.
That is, the drilling tool according to the present invention has a long shaft-shaped tool body that rotates about an axis, a cutting edge portion is formed on the front end side, and a rear end side is a shank portion. In a drilling tool that is attached to a cutting tool via a guide bush that guides the main body, is inserted into a prepared hole formed in advance in the workpiece, and cuts the inner wall surface of the prepared hole to form a processed hole. On the rear end side of the cutting edge portion, in a cross section perpendicular to the axis, a plurality of arcuate shapes arranged at intervals on a circumference of an outer diameter that can be in sliding contact with the inner peripheral wall surface of the guide bush. A guided portion having a contact circumferential surface and a clearance surface disposed between the contact circumferential surfaces and recessed inward of the circumference is provided.

  According to the hole drilling tool having such a feature, when the drilling tool is mounted on the cutting tool, even if the tip of the cutting edge comes out of the guide bush, the contact circumferential surface of the guided part on the rear end side is reduced. Since it is in sliding contact with the inner peripheral wall surface of the guide bush, it is possible to guide the drilling tool toward the tip end side in the axial direction while ensuring that the axes of the drilling tool and the cutting tool coincide with each other.

  Further, the clearance surface of the guided portion is configured to be recessed inward from the circumference where the contact circumferential surface is located in a cross section perpendicular to the axis, thereby contacting the inner circumferential wall surface of the guide bush. Since only the contact circumferential surface is provided, the contact area between the guided portion of the drilling tool and the inner peripheral wall surface of the guide bush can be reduced as much as possible, and the burnishing torque due to sliding contact with the guide bush is reduced. It becomes possible.

  In the drilling tool according to the present invention, the contact circumferential surface is arranged at the position of the apex of a regular polygon from a regular triangle to a regular dodecagon.

  For example, when two are provided so that the contact circumferential surface is opposed to the outer periphery of the guided portion, only the two locations are in sliding contact with the inner peripheral wall surface of the guide bush, resulting in poor balance. There is a possibility that the axis line between the hole machining tool and the cutting tool is displaced. Further, in the case of a polygon having more vertices than a regular dodecagon, the number of steps in processing is increased, and processing takes a lot of time and labor. Therefore, as in the present invention, by forming the guided portion so as to arrange the contact circumferential surface at the apex of the regular dodecagon from the regular triangle, the guide action by the guide bush is ensured, It is possible to easily form the guided portion.

  Moreover, in the drilling tool which concerns on this invention, it is preferable that the said clearance surface is formed in planar shape.

  The clearance surface may be, for example, a convex shape or a concave shape. However, the clearance surface can be easily formed and processed by using a planar shape.

  According to the drilling tool according to the present invention, by providing a guided portion in the tool body, the guide action by the guide bush is ensured to the maximum, and the axes of the drilling tool and the cutting tool are made to coincide with each other. Can be sent to the front end side in the axial direction, and the vanishing torque due to the sliding contact with the guide bush can be reduced as much as possible, and the machining accuracy can be improved.

  Hereinafter, a reamer which is an embodiment of a drilling tool of the present invention will be described in detail with reference to the drawings. 1 is a partially cutaway side sectional view showing a reamer according to an embodiment of the present invention, FIG. 2 is a front view of the reamer according to an embodiment of the present invention, and FIG. 3 is a sectional view taken along line AA in FIG. FIG. 4 is a view showing a reamer according to an embodiment of the present invention mounted on a cutting tool.

  As shown in FIG. 4, the reamer according to the present embodiment is attached to the cutting tool 40 via a cylindrical guide bush 41 fitted at the tip of the attachment hole 40 a of the cutting tool 40.

  As shown in FIG. 1, the reamer has a tool body 12 having a long shaft shape centering on the axis O, and the rear end side (upper side in FIG. 1) of the tool body 12 is a shank portion 13. The tip end side (lower side in FIG. 2) of the tool main body 12 is a cutting edge portion 14.

  The shank portion 13 is made of a steel material or the like, has a cylindrical shape having a slightly smaller diameter than the inner peripheral wall surface 41a of the guide bush 41, and the rear end side portion is attached to the cutting tool 40 or the cutting tool 40, for example. The mounting portion 15 is held by a collet chuck or the like provided on a main end shaft of a machine tool (not shown).

  Further, a V-shaped groove 16 having a central portion recessed in a V shape toward the rear end side of the shank portion 13 is formed on the front end surface of the shank portion 13 so that the bottom of the groove is perpendicular to the axis O and is V-shaped. The bisector is formed so as to be positioned on the axis O. Further, a coolant supply hole 18 is formed so as to penetrate along the axis O from the rear end surface 17 of the shank portion 13 toward the front end side, and the coolant supply hole 18 is formed in the V-shaped groove 16 on the front end side. It is open.

  The cutting edge portion 14 has a substantially multi-stage columnar shape centering on an axis O made of cemented carbide, and its rear end portion has the same diameter as the shank portion 13 and slightly smaller than the inner peripheral wall surface 41a of the guide bush 41. The rear end surface is provided with a convex portion 20 having a convex V-shaped cross section that can be fitted into the V-shaped groove 16 formed on the front end surface of the shank portion 13. A V-shaped bisector is formed on the axis O so as to be orthogonal to the axis O. The cutting edge portion 14 and the shank portion 13 are fixed and integrated by brazing the convex portion 20 and the V-shaped groove 16.

  A plurality of chip discharge grooves 21 extending toward the rear end side of the tool main body 12 are arranged on the outer periphery of the tip of the cutting edge portion 14. In this embodiment, as shown in FIG. 2, six chips are discharged. A groove 21 is disposed. In the present embodiment, the chip discharge grooves 21 are arranged at unequal intervals in the tool rotation direction T.

  Further, the cutting blade portion 14 is formed so as to extend along the axis O, and opens to the convex portion 20 at the rear end portion, and communicates with the coolant supply hole 18 of the shank portion 13. Is provided. In addition, a discharge hole 23 is provided that extends from the tip side portion of the communication path 22 toward the chip discharge groove 21 and is opened to the bottom of the groove.

  Further, the cutting edge portion 14 is provided with a back taper so that the outer diameter gradually becomes smaller toward the rear end side of the tool body 12, and the back taper amount is 0.03 mm to 0.04 mm per 100 mm. Has been.

  The tip surface of the cutting edge portion 14 has a flat portion 25 in which the vicinity of the axis O is a flat surface perpendicular to the axis O, and a progressive tool as it is arranged on the outer peripheral side of the flat portion 25 and goes radially outward. The main body 12 includes a taper portion 26 that recedes toward the rear end side. And the outer peripheral cutting edge 27 is formed in the wall surface which faces the tool rotation direction T front side of the chip discharge groove 21 and the cross ridge line part of the outer peripheral surface connected to the tool rotation direction T rear side of the chip discharge groove 21. Further, a tip cutting edge 28 that is continuous with the outer peripheral cutting edge 27 is formed at a crossing ridge line portion between the wall surface of the chip discharge groove 21 facing the front side in the tool rotation direction T and the tapered portion 26 of the cutting edge portion 14.

  Further, the wall surface of the chip discharge groove 21 facing the front side in the tool rotation direction T is a rake face, and the outer peripheral surface of the chip discharge groove 21 connected to the rear side in the tool rotation direction T is an outer peripheral flank. A tapered portion 26 that continues to the rear side in the tool rotation direction T is a tip flank.

  The tip flank connected to the tip cutting edge 28 is configured to incline toward the inner side in the radial direction of the tool body 12 as it goes rearward in the tool rotation direction T. In this embodiment, the tip flank is connected to the tip cutting edge 28. The portion is a first flank, and is a second flank with a clearance angle of 15 ° on the back side of the first flank in the tool rotation direction T. It is formed to be large.

  Further, the rotation trajectory formed by the outer peripheral cutting edge 27 about the axis O is a substantially cylindrical surface centered on the axis O in the present embodiment, and the axis of the outer peripheral cutting edge 27 connected to all the front end cutting edges 28. The radial distance from O is the same.

  Then, on the rear end side of the cutting edge portion 14, as shown in FIG. 4, the portion located at the tip end portion of the guide bush 41 in a state where it is attached to the cutting tool 40 via the guide bush 41 is described in detail. As shown in FIG. 3, in the cross section perpendicular to the axis O, there are six circular arcs arranged at equal intervals on the circumference of the outer diameter that can slide in contact with the inner peripheral wall surface 41a of the guide bush 41. Of the contact circumferential surface 31 and a clearance surface 32 disposed between the contact circumferential surfaces 31 so as to be recessed inside the circumference. It has been. That is, the guided portion 30 has an abutting circumferential surface 31 having substantially the same diameter as the inner circumferential wall surface 41 a of the guide bush 41, and a circle whose arc is the corresponding circumferential surface 31 is perpendicular to the axis O. The cross section is chamfered to have a regular hexagonal shape, and a contact circumferential surface 31 is interposed at each vertex of the regular hexagon.

  In the reamer configured as described above, the tool body 12 is inserted from the opening on the distal end side of the guide bush 41, and the mounting portion 15 of the tool body 12 is, for example, a cutting tool 40 or a work (not shown) to which the cutting tool 40 is attached. The reamer is mounted on the cutting tool 40 by being held by a collet chuck or the like provided on the main end shaft of the machine. At this time, as shown in FIG. 4, a slight clearance is provided between the outer peripheral surface of the shank portion 13 and the inner peripheral wall surface 41 a of the guide bush 41.

  Then, the tool body 12 is rotated around the axis O together with the cutting tool 40 by the reamer, and is sent toward the tip side in the direction of the axis O while being guided by the guide bush 41, and is prepared in advance in the workpiece. For example, it is inserted into a valve stem guide hole or the like in a cylinder head of an engine, and the inner wall surface of this pilot hole is cut to form a processed hole having a predetermined inner diameter.

  When cutting with this reamer, the cutting fluid is supplied from the machine tool to the coolant supply hole 18 of the shank portion 13 of the tool body 12 through a pipe. The cutting fluid supplied to the coolant supply hole 18 flows into the distal end side of the tool body 12 and is discharged from the discharge hole 23 to the groove bottom portion of the chip discharge groove 21 through the communication path 22 of the cutting edge portion 14.

  According to the reamer of the present embodiment, when the tool main body 12 is inserted into the guide bush 41 of the cutting tool 40 and mounted, the contact circumferential surface 31 of the guided portion 30 is the inner peripheral wall surface 41a of the guide bush 41. The tool body 12 is guided to the tip side in the direction of the axis O while ensuring that the axes of the tool body 12 and the cutting tool 40 coincide with each other even if the tip side of the cutting edge portion 14 comes out of the guide bush 41. Is possible.

  In addition, the clearance surface 32 of the guided portion 30 is configured to be recessed inward from the circumference where the contact circumferential surface 31 is located in a cross section perpendicular to the axis O, so that the inside of the guide bush 41 Since only the contact circumferential surface 31 is in contact with the peripheral wall surface 41a, the contact area between the guided portion 30 of the tool body 12 and the inner peripheral wall surface 41a of the guide bush 41 can be reduced as much as possible. It is possible to reduce the burnishing torque that acts on the tool body 12 from 41.

  Therefore, the guide action by the guide bush 41 can be ensured to the maximum, the axis of the reamer tool body 12 and the cutting tool 40 can be matched, and the tool body 12 can be sent to the front end side in the axis O direction. Since the vanishing torque applied to the tool main body 12 can be reduced as much as possible by 41, the tool main body 12 can be prevented from being broken, and the machining accuracy and the tool life can be improved. .

  Further, in the present embodiment, the contact circumferential surface 31 of the guided portion 30 is disposed at the position of the optimal regular hexagonal apex among regular triangles to regular dodecagons. Can be ensured optimally, and the processability of the guided portion can be obtained.

  That is, for example, when two are provided so that the contact circumferential surface 31 faces the outer periphery of the guided portion 30, only the two locations are in sliding contact with the inner peripheral wall surface 41a of the guide bush 41. Therefore, the axis of the tool body 12 and the cutting tool 40 may be displaced in a direction perpendicular to the direction in which the two contact circumferential surfaces 31 face each other. Further, in the case of a polygon having more vertices than a regular dodecagon, the number of steps in processing is increased, and processing takes a lot of time and labor. For the above reasons, the contact circumferential surface 31 is preferably disposed at the apex of a regular dodecagon to a regular dodecagon, but in this embodiment, among such polygons, a regular hexagonal shape is also used. Since it is configured to be placed at the apex position, it is possible to optimally ensure guideability and ease of processing.

  Further, since the clearance surface 32 of the guided portion 30 has a flat shape, it can be easily formed by chamfering a circle with the contact circumferential surface 31 as an arc in a cross section perpendicular to the axis O. It becomes possible to do.

  As mentioned above, although the reamer which is embodiment of the drilling tool 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, although the chip discharge groove 21 has been described as having no twist, the present invention is not limited to this, and is gradually twisted toward the front side of the tool rotation direction T as it goes toward the rear end side of the tool body 12. Alternatively, it may be twisted so as to gradually go to the rear side of the tool rotation direction T as it goes to the rear end side of the tool body 12.

It is the sectional side view which fractured | ruptured a part which shows the reamer which is embodiment of this invention It is a front view of the reamer which is an embodiment of the invention. It is AA sectional drawing in FIG. It is a figure which shows the reamer which is embodiment of this invention with which the cutting tool was mounted | worn.

Explanation of symbols

12 Tool body 13 Shank portion 14 Cutting edge portion 30 Guided portion 31 Contact circumferential surface 40 Cutting tool 41 Guide bush 41a Inner circumferential wall surface O Axis line

Claims (3)

A cutting tool having a long shaft-shaped tool body that is rotated around an axis, a cutting edge portion is formed on the tip side, and a shank portion on the rear end side, and a guide bush that guides the tool body In a hole processing tool that is inserted into a prepared hole that is previously formed in the workpiece and cuts the inner wall surface of the prepared hole to form a processed hole,
On the rear end side of the cutting edge portion, in a cross section perpendicular to the axis, a plurality of arcuate shapes arranged at intervals on a circumference of an outer diameter capable of sliding contact with the inner peripheral wall surface of the guide bush Characterized in that a guided portion having a contact circumferential surface and a clearance surface disposed between the contact circumferential surfaces and recessed inward of the circumference is provided. Drilling tool.   2. The drilling tool according to claim 1, wherein the contact circumferential surface is disposed at a vertex of a regular polygon from a regular triangle to a regular dodecagon.   The hole machining tool according to claim 1, wherein the clearance surface is formed in a flat shape.

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