JP4212991B2 - Drilling tool - Google Patents

Description

  The present invention relates to a hole machining tool for machining a hole formed in a workpiece into a predetermined shape, such as a valve hole in a cylinder head of an engine.

In this type of drilling tool, a long, substantially cylindrical reamer (drilling tool) is mounted coaxially with the above-mentioned axis in a mounting hole drilled in the tip surface of the tool body rotated about the axis. And the cutting blade which inclines with respect to the said axis line is provided in the front-end | tip part outer periphery of a tool main body (for example, refer patent document 1).
Then, when the tool main body is rotated around its axis and sent toward the tip end side in the axial direction, the reamer mounted in the mounting hole of the tool main body is, for example, a valve hole (formed on the workpiece in the cylinder head of the engine). And the cutting head provided on the outer periphery of the tip of the tool body has a valve head at the opening of the valve hole (the opening of the machining hole formed in the workpiece). An abutting valve seat surface is formed.

In addition, in such a hole drilling tool, the back body force of the cutting force acting on the cutting blade during machining causes the tool body to be swung to the opposite side of the cutting blade, resulting in chatter vibration, and machining accuracy. There is a problem that it causes a decrease in
Therefore, a pad having a guide surface that can be slidably contacted with the processing surface processed by the cutting blade is provided on the outer periphery of the tip of the tool body so as to be positioned on the substantially opposite side of the cutting blade with the axis line in between. Thus, machining is performed while the tool body is guided by the guide pad.

  By the way, as shown in FIG. 6, the valve seat surface 101 formed at the opening of the valve hole 100 is directed from the hole back side (left side in FIG. 6) of the valve hole 100 toward the opening side (right side in FIG. 6). Accordingly, the taper angles θ1, θ2, θ3 are often formed in a multi-step taper shape composed of first to third taper surfaces 110, 120, 130 (a plurality of taper surfaces) that gradually increase (valve seat surface). Among the first to third tapered surfaces 110, 120, 130 constituting 101, the taper angle θ 1 of the first tapered surface 110 located on the deepest side of the hole is 60 °, and the second taper continues to the first tapered surface 110. The taper angle θ2 of the surface 120 is 90 °, and the taper angle θ3 of the third taper surface 130 which is continuous with the second taper surface 120 and located on the most opening side is set to 120 ° (θ1 <θ2 <θ3)).

As described above, when the valve seat surface 101 has a multi-step taper shape, the tool blade main body has a first blade (an inclination angle with respect to the axis of the tool main body on the outer periphery of the tip portion). θ1 / 2), a second cutting edge for forming the second tapered surface 120 (the inclination angle of the tool body with respect to the axis O is set to θ2 / 2), and a third tapered surface 130 The third cutting edge for forming (the inclination angle with respect to the axis of the tool body is set to θ3 / 2) is provided at substantially equal intervals in the circumferential direction of the tool body, and these first to third cutting edges The first to third pads are provided so as to be positioned substantially opposite to each other with the axis therebetween.
JP 2002-59313 A

However, in a conventional drilling tool in which a plurality of cutting blades (first to third cutting blades) and a plurality of pads (first to third pads) are provided on the outer periphery of the tip of the tool body, a guide for the plurality of pads is used. The inclination angles of all the surfaces are set to be the same as one of the plurality of cutting blades, and the positions of all the guide surfaces of the plurality of pads are retracted by a predetermined amount from the one cutting blade to the rear end side of the tool body. It was only allowed.
Therefore, it is impossible to effectively receive the back component force of the cutting resistance acting on each of the plurality of cutting blades during machining, and it is possible to reliably suppress chatter vibration generated in the tool body due to this. It was impossible.

  This invention is made | formed in view of the said subject, and aims at providing the drilling tool which can suppress the chatter vibration which arises in a tool main body reliably.

In order to solve the above problems and achieve such an object, the present invention employs the following configuration.
In other words, the invention according to claim 1 is configured so that the opening portion of the machining hole formed in the workpiece is formed from a plurality of taper surfaces whose taper angles sequentially increase from the hole back side to the opening side of the machining hole. And a plurality of cutting blades for forming each of the plurality of taper surfaces on the outer periphery of the tool body rotated about the axis, and A plurality of pads are provided so as to be positioned substantially opposite to each of the cutting edges with respect to the axis, and an inclination angle formed by each of the plurality of cutting edges with respect to the axis, and the cutting blade In contrast, an inclination angle formed by the guide surface of the pad located substantially opposite to the axis with respect to the axis is set to be substantially the same.

In the first aspect of the present invention, a pad having a guide surface having the same inclination angle as that of the cutting edge is provided so as to be positioned on the substantially opposite side with respect to each of the plurality of cutting edges. Yes.
For this reason, the tool main body is guided while being slidably brought into contact with the taper surface processed by the one cutting edge by sliding the guide surface of the pad located on the substantially opposite side of the one cutting edge. Therefore, out of the cutting resistance acting on each of the plurality of cutting blades, it is possible to effectively receive the back component force acting toward the opposite side across the axis, and reliably prevent chatter vibration generated in the tool body. Can be suppressed.

Hereinafter, embodiments of the present invention will be described with reference to FIGS.
The hole drilling tool according to the first embodiment of the present invention is used to form the valve seat surface 101 having the shape as shown in FIG. 6 described above, and the tool body 10 is as shown in FIG. In addition, it has a substantially multi-stage cylindrical shape centered on the axis O rotated about the axis O.
An attachment hole 12 centering on the axis O extending toward the rear end side in the axis O direction is formed in the tip surface 11 located at the tip of the tool body 10. Although omitted, a reamer as a long and substantially cylindrical hole drilling tool is mounted coaxially with the axis O.

  The first tip 21, the second tip 22, and the third tip 23 are attached to the outer periphery of the tip of the tool body 10 so as to be arranged at substantially equal intervals in the circumferential direction of the tool body 10. Accordingly, the substantially straight first blade 21 </ b> A formed on the first tip 21, the substantially straight second cutting edge 22 </ b> A formed on the second tip 22, and the substantially straight shape formed on the third tip 23. The third cutting edge 23 </ b> A is provided so as to be arranged at substantially equal intervals in the circumferential direction of the tool body 10.

  Here, as shown in FIG. 2, the first and third cutting edges 21 </ b> A, 22 </ b> A, and 23 </ b> A have rotational trajectories around the axis O, and the first blade 21 </ b> A has the valve seat surface 101 shown in FIG. 6. The first tapered surface 110 is formed, the second cutting edge 22A forms the second tapered surface 120 of the valve seat surface 101 shown in FIG. 6, and the third cutting edge 23A forms the valve seat surface shown in FIG. 101 is arranged to form a third tapered surface 130.

  Therefore, the first blade 21A (the rotation trajectory around the axis O of the first blade 21A) has an inclination angle corresponding to the first tapered surface 110 (an inclination angle of θ1 / 2 with respect to the axis O). The cutting edge 22A (the rotation trajectory of the second cutting edge 22A around the axis O) has an inclination angle corresponding to the second taper surface 120 (an inclination angle of θ2 / 2 with respect to the axis O) as the third cutting edge 23A ( An inclination angle corresponding to the third taper surface 130 (an inclination angle of θ3 / 2 with respect to the axis O) is given to the rotation trajectory of the third cutting edge 23A around the axis O, and the first cutting edge 21A. The second cutting edge 22A and the third cutting edge 23A overlap the rotation trajectories around the axis O.

  At this time, the valve seat surface 101 to be formed has a multi-step tapered shape as shown in FIG. 6, and the contact length of the first blade 21A with respect to the first tapered surface 110 is the second of the second cutting blade 22A. Since the contact length with respect to the taper surface 120 is larger, the back component force of the cutting force acting on the first to third cutting edges 21A, 22A, and 23A is the first cutting edge 21A and the second cutting edge. 22A and the third cutting edge 23A become smaller in order, and the main component of the cutting resistance acting on the first to third cutting edges 21A, 22A and 23A is also the first cutting edge 21A and the second cutting edge 22A. The third cutting edge 23A becomes smaller in this order.

  Correspondingly, the first blade 21A, the second cutting blade 22A, and the third cutting blade 23A arranged at substantially equal intervals in the circumferential direction of the tool body 10 have the largest back force and main component. The third cutting edge 23A and the second cutting edge 22A are sequentially arranged on the rear side in the tool rotation direction T of the first cutting edge 21A with reference to the first cutting edge 21A on which the force acts.

Further, a first pad 31 is provided on the outer periphery of the tip of the tool body 10 so as to be positioned on the substantially opposite side of the first blade 21A with the axis O interposed therebetween, and the axis of the second cutting blade 22A. A second pad 32 is provided so as to be positioned substantially on the opposite side across O, and a third pad 33 is provided so as to be positioned on the substantially opposite side across the axis O with respect to the third cutting edge 23A. .
Each of the first to third pads 31, 32, 33 has first to third guide surfaces 31A, 32A, 33A that can be slidably contacted with the processing surface processed by the cutting blade, and their axes. The rotation trajectory around O is as shown in FIGS.

  As shown in FIG. 3, the rotation trajectory of the first guide surface 31A around the axis O is such that the inclination angle with respect to the axis O is substantially opposite to the axis O of the first guide surface 31A (first pad 31). The first guide surface 31A is formed by the first blade 21A. The inclination angle (θ1 / 2) of the first blade 21A positioned at the axis O with respect to the axis O is set substantially the same. The first tapered surface 110 can be slidably contacted.

Further, the rotation trajectory around the axis O of the first guide surface 31A is a retraction amount S1 toward the rear end side (left side in FIG. 3) in the axis O direction with respect to the first blade 21A forming the first tapered surface 110. Has been retreated only.
The retraction amount S1 is from the first blade 21A toward the rear side in the tool rotation direction T, beyond the second pad 32, and the second pad 31 (relative to the axis O of the first blade 21A). The central angle α1 [°] (in the present embodiment, α1 = 180 °) with respect to the axis O of the region up to the first guide surface 31A of the first pad 31) located substantially on the opposite side, and the tool body 10 makes one rotation. Each time the tool body 10 is fed toward the tip side in the direction of the axis O, the feed amount fr [mm / rev. Specifically, the retraction amount S1 is (α1 / 360 °) × fr [mm / rev. ] Is set.

  As shown in FIG. 4, the rotation trajectory of the second guide surface 32A around the axis O is such that the inclination angle with respect to the axis O is substantially opposite to the axis O of the second guide surface 32A (second pad 32). Is set to be substantially the same as the inclination angle (θ2 / 2) with respect to the axis O of the second cutting edge 22A located at the second cutting edge 22A, and this second guide surface 32A is formed by the second cutting edge 22A. The second tapered surface 120 can be slidably contacted.

Further, the rotation trajectory around the axis O of the second guide surface 32A is a retraction amount S2 toward the rear end side (left side in FIG. 4) in the axis O direction from the second cutting edge 22A forming the second tapered surface 120. Has been retreated only.
The retraction amount S2 is the second pad 32 (second axis 22 with respect to the axis O of the second cutting edge 22A) positioned second from the second cutting edge 22A toward the rear side in the tool rotation direction T beyond the third pad 33. The central angle α2 [°] (in the present embodiment, α2 = 180 °) with respect to the axis O for the region up to the second guide surface 32A of the second pad 32) located substantially on the opposite side, and the tool body 10 makes one rotation. Each time the tool body 10 is fed toward the tip side in the direction of the axis O, the feed amount fr [mm / rev. More specifically, the retraction amount S2 is (α2 / 360 °) × fr [mm / rev. ] Is set.

  As shown in FIG. 5, the rotation trajectory of the third guide surface 33A around the axis O is such that the inclination angle with respect to the axis O is substantially opposite to the axis O of the third guide surface 33A (third pad 33). Is set to be substantially the same as the inclination angle (θ3 / 2) with respect to the axis O of the third cutting edge 23A located at the third cutting edge 23A, and this third guide surface 33A is formed by the second cutting edge 23A. The third tapered surface 130 can be slidably contacted.

Further, the rotation trajectory around the axis O of the third guide surface 33A is a retraction amount S3 toward the rear end side (left side in FIG. 5) in the axis O direction from the third cutting edge 23A forming the third tapered surface 130. Has been retreated only.
The retraction amount S3 is the third pad 33 (second axis with respect to the axis O of the third cutting edge 23A) positioned second from the third cutting edge 23A toward the rear side in the tool rotation direction T beyond the first pad 31. The central angle α3 [°] (in the present embodiment, α3 = 180 °) with respect to the axis O for the region up to the third guide surface 33A of the third pad 33) located substantially on the opposite side, and the tool body 10 makes one rotation. Each time the tool body 10 is fed toward the tip side in the direction of the axis O, the feed amount fr [mm / rev. Specifically, the retraction amount S3 is (α3 / 360 °) × fr [mm / rev. ] Is set.

  In the present embodiment as described above, the tilt angle is the same as the tilt angle (θ1 / 2) of the first blade 21A so as to be positioned on the substantially opposite side across the axis O of the first blade 21A. The first pad 31 having the first guide surface 31A is provided, and the second cutting blade 22A is positioned on the substantially opposite side across the axis O of the second cutting blade 22A. The second pad 32 having the second guide surface 32A having the same inclination angle is provided, and is positioned on the substantially opposite side across the axis O of the third cutting edge 23A, so that the inclination angle (θ3 / 2) is provided with a third pad 33 having a third guide surface 33A having the same inclination angle.

For this reason, the first guide surface 31A of the first pad 31 positioned on the substantially opposite side across the axis O of the first blade 21A with respect to the first tapered surface 110 processed by the first blade 21A. The second guide surface of the second pad 32 located on the substantially opposite side with respect to the second taper surface 120 that is slidably contacted and processed by the second cutting blade 22A. The third pad 33 is located on the substantially opposite side of the third taper surface 130 with the axis O of the third cutting edge 23A against the third tapered surface 130 processed by the third cutting edge 23A. The guide surface 33A can be slid in contact with the tool body 10 for processing.
Therefore, among the cutting resistances acting on the first to third cutting edges 21A, 22A, and 23A, the back force acting toward the substantially opposite side across the axis O can be effectively received. The chatter vibration generated in the tool body 10 can be reliably suppressed.

It is explanatory drawing when the tool main body of the drilling tool by embodiment of this invention is seen from the front end side of the axial direction. It is explanatory drawing which shows the positional relationship of the opening part of a processing hole, and a cutting blade. It is explanatory drawing which shows the positional relationship of the opening part of a process hole, a cutting blade, and a pad. It is explanatory drawing which shows the positional relationship of the opening part of a process hole, a cutting blade, and a pad. It is explanatory drawing which shows the positional relationship of the opening part of a process hole, a cutting blade, and a pad. It is sectional drawing which shows the valve seat surface formed in the opening part of a valve hole.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Tool main body 21 First tip 21A First all blade 22 Second tip 22A Second cutting blade 23 Third tip 23A Third cutting blade 31 First pad 31A First guide surface 32 Second pad 32A Second guide surface 33 First Three-pad 33A Third guide surface 100 Valve hole 101 Valve seat surface 110 First taper surface 120 Second taper surface 130 Third taper surface O Axis T Rotation direction

Claims (1)

Drilling holes for machining multi-tapered holes consisting of multiple taper surfaces where the taper angle increases sequentially from the hole back to the opening side of the hole. A tool,
A plurality of cutting blades forming each of the plurality of tapered surfaces are provided on the outer periphery of the tool main body rotated about the axis, and are substantially opposite to each of the plurality of cutting blades with the axis line interposed therebetween. A plurality of pads are provided to be located,
An inclination angle formed by each of the plurality of cutting blades with respect to the axis, and an inclination angle formed by the guide surface of the pad positioned on the substantially opposite side with respect to the cutting blade with respect to the axis. Are set to be approximately the same.

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