JP2001129712A - Boring tool - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stably introduce a cutting medium between guide pads and the wall faces of holes to stably perform high precision boring, in a boring tool in which a cutting edge is provided at the tip of a rotary shaft, and guide pads extending in the axial direction of the rotary shaft are provided at required intervals circumferentially on the outer peripheral part of the rotary shaft in the rear of the cutting edge. SOLUTION: In a boring tool in which a cutting edge 24 is provided at the tip of a rotary shaft 21 and plural guide pads 25, each of which has an axially extending, required width T, are provided at required intervals circumferentially on the outer peripheral part of the rotary shaft in the rear of the cutting edge, flanks 6 are formed between the guide pads, grooves 27 are provided in the central parts of the guide pads, and plural holes 29 for introducing a cutting medium into the respective grooves are provided at required intervals.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a drilling tool used for drilling a hole or further processing a previously provided hole to improve the accuracy of the hole.
In particular, a cutting blade is provided at the tip end of the rotating shaft, and a plurality of guide pads of a required width extending in the axial direction are provided at required intervals in the circumferential direction on an outer peripheral portion of the rotating shaft behind the cutting blade. The hole drilling tool is characterized in that a cutting medium is appropriately supplied between the guide pad and the wall surface of the hole so that stable and accurate hole drilling can be performed.

[0002]

2. Description of the Related Art Conventionally, as a drilling tool, a drill for drilling, a burnishing drill for finishing the wall surface of the hole together with the drilling, a reamer or a boring cutter for further processing the previously provided hole to improve the accuracy of the hole. Etc. are used.

[0003] In such a drilling tool, a guide pad of a required width extending in the axial direction is generally provided on the outer peripheral portion of the rotary shaft behind the cutting edge at the tip of the rotary shaft. The pad was brought into contact with the wall of the hole to make a straight hole.

However, when the guide pad is formed on the outer peripheral portion of the rotating shaft in this way, the cut chips enter between the guide pad and the wall surface of the hole, and the chips are removed from the guide pad and the wall surface of the hole. There is a problem that the accuracy of the hole is deteriorated.

For this reason, in the case of a burnishing drill as shown in FIGS. 1A and 1B, the vicinity of the cutting blade 2 provided at the tip of the rotary shaft 1 and a discharge groove for discharging chips. 3
Is provided with a guide hole 4 for guiding a cutting medium such as oil, and the cutting medium is ejected from each guide hole 4 through a flow path 5 provided at the center of the rotary shaft 1, and the cutting medium is used by the cutting medium. In addition to preventing the chips from sticking to the surface 2, a part of the cutting medium is guided between the guide pad 6 and the wall of the hole to prevent the chips from sticking to the guide pad 6 and the wall of the hole. Was like that.

In the case of a boring cutter as shown in FIGS. 2 (A) and 2 (B), a hole 10 is provided behind the cutting blade 2 of the throw-away tip 7 provided at the tip of the rotating shaft 1. A plurality of guide pads 6 having a required width in contact with the wall surface 11 are provided at predetermined intervals in the circumferential direction, and the guide holes 4 for guiding the cutting medium between the guide pads 5 provided in this manner are formed in the rotary shaft 1. A plurality of cutting media are provided at required intervals in the axial direction, and a cutting medium is ejected from each guide hole 4 through a flow path 5 at the center of the rotating shaft 1, and the cutting medium is formed between the guide pad 6 and the wall surface 11 of the hole 10. It was guided in between to prevent chips from sticking to the guide pad 6 and the wall surface 11 of the hole 10.

However, when a cutting medium such as oil is ejected from each guide hole in a burnishing drill or a boring cutter as described above, the ejected cutting medium is obstructed by the cut chips or the like, and this cutting medium is cut off. There is a problem that the medium for use is not supplied well between the guide pad and the wall surface of the hole, and chips are still seized on the wall surface of the guide pad and the hole, so that accurate hole processing cannot be performed.

[0008]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems in a drilling tool for performing drilling and finishing of a hole.
A cutting blade is provided at the tip of the rotating shaft, and a plurality of guide pads extending in the axial direction are provided on the outer peripheral portion of the rotating shaft behind the cutting blade at required intervals in the circumferential direction for hole drilling. In the tool, the cutting medium is stably guided between the guide pad and the wall surface of the hole, and the chip is prevented from sticking to the wall surface of the guide pad and the hole. It is an object to be able to do so.

[0009]

In the drilling tool of the present invention, in order to solve the above-mentioned problems, a cutting edge 24 is provided at the tip of the rotating shaft 21 and is provided with a cutting edge. In a drilling tool in which a plurality of guide pads 25 of a required width extending in the axial direction are provided on the outer peripheral portion of the rotating shaft 21 at the rear side at a required interval in the circumferential direction, the flank 26 is provided between the guide pads 25. At the same time, a groove 27 is formed along the guide pad 25 at the center of each guide pad 25, and a plurality of guide holes 29 for guiding the cutting medium are provided in each groove 27 at a required interval. is there.

When drilling is performed using the drilling tool according to the present invention, a cutting medium is supplied into each groove 27 provided at the center of each guide pad 25 through the guide holes 29. In this manner, the cutting medium supplied into each groove 27 is appropriately guided between each guide pad 25 and the wall surface of the hole, so that chips are burned on the guide pad 25 and the wall surface of the hole. As a result, it is possible to stably perform accurate hole drilling, and the cut chips are discharged through the flank 26 between the guide pads 25, so that the chips are removed from the guide pad 25 and the wall surface of the hole. Also, the clogging between them is suppressed.

Further, when the positions of the guide holes 29 provided in each groove 27 are made different at least in the adjacent grooves 27, when a plurality of holes are machined at one time, the holes are not formed. Even if there is a space between them, the cutting medium supplied into the respective grooves 27 from the guide holes 29 flows through the respective grooves 27, so that there is sufficient space between the guide pad 25 and the wall surface of the respective holes. And the guide pad 25
Burning of the chips between the hole and the wall surface of each hole is prevented, so that a plurality of holes can be machined with high accuracy.

Further, as set forth in claim 3, the ratio of the width y of the groove 27 to the width T of the guide pad 25 is set in the range of 20 to 50%. The actual width (T-y) of the guide pad 25 obtained by subtracting the width y of the groove 27 from the width T of the pad 25 is 2 to 8 m.
m, or the sum of the width T of each guide pad 25 with respect to the circumferential length L = D · π (D is the diameter of the rotating shaft) of the rotating shaft 21 as described in claim 5. The ratio of length NT (N is the number of guide pads) is 30-50%
In this range, the advancing direction of the hole drilling tool is appropriately regulated by the guide pad 25 so that straight hole drilling can be performed, and the cutting medium supplied from the guide hole 29 into each groove 27 is formed by the guide pad 25 and the guide pad 25. Since it is supplied appropriately between the hole and the wall surface, more accurate hole processing can be performed.

Further, when the number N of the guide pads 25 provided on the outer peripheral portion of the rotary shaft 21 is 4 or more, in order to satisfy each of the above-mentioned conditions 3 to 5, there is shown in claim 6. Thus, the number N and the circumferential length L of the rotating shaft 21
Must satisfy the condition of 0.3 L / 16 ≦ N ≦ 0.5 L / 2.5.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A drilling tool according to an embodiment of the present invention will be specifically described below with reference to the accompanying drawings.

In this embodiment, an example in which the drilling tool is a boring cutter is shown. However, the drilling tool of the present invention is not limited to a boring cutter, and may be a drill, a burnishing drill, a reamer, or the like. Any tool may be used as long as it is a tool for drilling holes.

Here, in the boring cutter in this embodiment, as shown in FIG. 3, a throw-away tip 22 is attached to a tip end of a rotating shaft 21 by a bolt 23, and a cutting blade provided on the throw-away tip 22 is provided. 24 cuts the previously provided hole.

A plurality of guide pads 25 having a required width T extending in the axial direction on the outer peripheral portion of the rotary shaft 21 behind the throw-away tip 22 at a certain interval in the circumferential direction. 4 and 5
As shown in FIG. 5, a flank 26 is formed between the guide pads 25, and a groove 27 having a required width y through which the cutting medium flows is provided along the guide pad 25 at the center of each guide pad 25. A guide hole 2 for guiding a cutting medium from a flow path 28 provided at the center of the rotating shaft 21 with respect to the shaft 27
9 are provided.

Here, in the boring cutter of this embodiment, as shown in FIG. 6, the guide hole 29 is inclined toward the tip end of the rotary shaft 21 from the flow path 28 toward each groove 27. And such a guide hole 2
A plurality of grooves 9 are provided in each groove 27 in the axial direction of the rotating shaft 21 at a required interval, and the position of the guide hole 29 in each groove 27 is slightly shifted.

In order to further process the previously provided hole to improve the accuracy of the hole by using the boring cutter in this embodiment, the above-described rotating shaft 21 is rotated, and the tip of the rotating shaft 21 is The cutting edge 24 of the provided throw-away tip 22 cuts the wall surface of the previously provided hole, and the cut-away tip 2
Each of the guide pads 25 provided on the rear side of the rotary shaft 21 with respect to the rotation shaft 2 regulates the traveling direction of the boring cutter, and cuts oil or the like supplied to a flow path 28 provided at the center of the rotary shaft 21. The medium is supplied through the guide holes 29 into the grooves 27 provided in the guide pads 25.

When drilling is performed in this way, the direction of advance of the boring cutter is regulated by each guide pad 25, so that a straight hole can be drilled, and at the same time, into each groove 27 through each guide hole 29. The supplied cutting medium such as oil is sufficiently guided between the guide pad 25 and the wall surface of the hole to prevent the guide pad 25 and the wall surface of the hole from being heated. Is prevented from sticking to the wall surfaces of the holes, and the wall surface of the holes can be accurately drilled, and the cut chips can be discharged through the flank 26 between the guide pads 25. Clogging between the guide pad 25 and the wall surface of the hole is also suppressed.

Next, when the boring cutter in the above embodiment is used to further process the previously provided hole to improve the hole accuracy, the above-mentioned width T of the guide pad 25 is set with respect to the width T of the guide pad 25. The ratio of the width y of the groove 27, the substantial width (T−y) of the guide pad 25 obtained by subtracting the width y of the groove 27 from the width T of the guide pad 25, and each guide pad 25 with respect to the circumferential length L of the rotating shaft 21. An experiment was conducted to determine a preferable range of the ratio of the total length NT (N is the number of guide pads) of the width T of the above.

Here, in this experiment, as a work piece to be drilled, a cylinder head made of an aluminum alloy (ADC12) was used. And each of the holes is provided with a hole having a diameter of 20 mm in each of the drilled portions.

On the other hand, as a boring cutter, the diameter D of the rotating shaft 21 is about 23.5 mm, and the width T of the guide pad 25, the width y of the groove 27, and the number N of the guide pads 25 are changed. What was made to be used was used.

When drilling holes with such a boring cutter, the cutting speed is set to 150 m.
m / min, the cutting feed rate is set to 0.12 mm / rev, and 20 kg / cm ^{2 of} an emulsion-based water-soluble cutting oil is discharged into each groove 27 provided in each guide pad 25 through each guide hole 29 described above. While discharging by pressure, the wall surface of the hole previously provided in each hole processing portion is cut by the cutting blade 24 of the throw-away tip 22 provided at the tip of the rotating shaft 21, and the diameter of each hole processing portion is 23. A 5 mm cam journal hole was machined, and the surface roughness (Ra) of the wall surface of the cam journal hole machined in this way was determined.

FIG. 7 shows the change in the surface roughness (Ra) of the wall surface of the cam journal hole when the ratio (y / T) of the width y of the groove 27 to the width T of the guide pad 25 is changed.
Next, the change in the surface roughness (Ra) of the wall surface of the cam journal hole when the substantial width (T−y) of the guide pad 25 obtained by subtracting the width y of the groove 27 from the width T of the guide pad 25 is illustrated. 8, the surface roughness (Ra) of the wall surface of the cam journal hole when the ratio (NT / L) of the total length NT of the width T of each guide pad 25 to the circumferential length L of the rotating shaft 21 is changed. 9 is shown in FIG.

As is apparent from the results, the ratio of the width y of the groove 27 to the width T of the guide pad 25 is set to 20 to 50.
%, The actual width (T-y) of the guide pad 25 obtained by subtracting the width y of the groove 27 from the width T of the guide pad 25 is 2 to 8 m.
When the ratio of the total length NT of the width T of each guide pad 25 to the circumferential length L of the rotating shaft 21 is set in the range of 30 to 50%, the surface of the cam journal hole on the wall surface is in any case. The roughness (Ra) was 1.0 or less, and a well-finished hole was formed.

Further, the rotation shaft 2 is adjusted so as to satisfy the above conditions.
When the guide pad 25 is provided on the outer peripheral portion of the first guide pad 25, the minimum of the total length NT of the width T of the guide pad 25 is 30% (0.3 L) of the circumferential length L of the rotating shaft 21, and the guide pad 2
5, the maximum of the width T is T = 0.5T + 8 = 16 (mm), and the minimum number Nmin of the guide pads 25 provided on the outer peripheral portion of the rotating shaft 21 is 0.3 L / 16. On the other hand, the maximum of the total length NT of the width T of the guide pad 25 is the rotation axis 2
1 is 50% (0.5 L) of the circumferential length L, and the minimum width T of the guide pad 25 is T = 0.2T + 2 = 2.5 (m
m), and the maximum number Nmax of the guide pads 25 provided on the outer peripheral portion of the rotating shaft 21 is 0.5 L / 2.5.
For this reason, the guide pad 2 provided on the outer peripheral portion of the rotary shaft 21
It is necessary to set the number N of 5 in the range of 0.3 L / 16 ≦ N ≦ 0.5 L / 2.5. Also in this case, it is preferable to set the number N of the guide pads 25 to 4 or more in order to appropriately regulate the traveling direction of the boring cutter by the guide pads 25 so that a straight hole can be machined.

[0028]

As described above in detail, in the hole drilling tool according to the present invention, the center of each guide pad having a required width extending in the axial direction on the outer peripheral portion of the rotating shaft behind the cutting edge is provided. A groove is provided along each guide pad, and a plurality of guide holes for guiding the cutting medium are provided at required intervals in each groove, and when drilling, the cutting medium is passed through each guide hole to the center of each guide pad. The cutting medium supplied in each groove is appropriately guided between each guide pad and the wall surface of the hole, and supplied to the guide pad and the wall surface of the hole. Prevents chips from burning,
While accurate hole drilling can be performed stably,
The cut chips are discharged through the flank between the guide pads, and the chips are prevented from being clogged between the guide pads and the wall surfaces of the holes.

Further, when the positions of the guide holes provided in each groove are made different at least in the adjacent grooves, when a plurality of holes are processed at one time, the distance between the holes may be reduced. Even if there is a space, the cutting medium supplied from the guide hole into each groove flows through each groove, and is sufficiently supplied between the guide pad and the wall surface of each hole. In addition, the seizure of chips between the guide pad and the wall surface of each hole is prevented, so that a plurality of holes can be machined with high accuracy.

Further, the ratio of the width y of the groove to the width T of the guide pad is set in the range of 20 to 50%, and the width of the groove is determined from the width T of the guide pad. The actual width of the guide pad (T−
y) is in the range of 2 to 8 mm, or the sum of the width T of each guide pad with respect to the circumferential length of the rotating shaft L = D · π (D is the diameter of the rotating shaft). Length NT
When the ratio of (N is the number of guide pads) is in the range of 30 to 50%, the guide pad appropriately regulates the traveling direction of the hole drilling tool so that straight hole drilling can be performed. The cutting medium supplied to the hole is appropriately supplied between the guide pad and the wall surface of the hole, so that more accurate hole processing can be performed.

[Brief description of the drawings]

FIG. 1 is a schematic side view and a schematic front view of a conventional burnishing drill provided with a guide hole for guiding a cutting medium.

FIG. 2 is a schematic explanatory view showing a use state of a conventional boring cutter provided with a guide hole for guiding a cutting medium, and a longitudinal sectional view of a rotating shaft of the boring cutter.

FIG. 3 is a schematic side view of a boring cutter according to a hole drilling tool according to an embodiment of the present invention.

FIG. 4 is a longitudinal sectional view of a rotating shaft in the boring cutter of the embodiment.

FIG. 5 is an enlarged cross-sectional view of a guide pad provided on a rotating shaft in the boring cutter of the embodiment.

FIG. 6 is a transverse cross-sectional view of a rotating shaft in the boring cutter of the embodiment.

FIG. 7 shows the relationship between the ratio of the width y of the groove to the width T of the guide pad and the surface roughness of the wall surface of the processed hole in an experiment in which a hole was formed using the boring cutter of the same embodiment. FIG.

FIG. 8 is a graph showing the actual width (T−y) of the guide pad obtained by subtracting the width y of the groove from the width T of the guide pad in an experiment in which a hole was drilled using the boring cutter of the embodiment. It is the figure which showed the relationship with the surface roughness of a wall surface.

FIG. 9 shows the ratio of the total length NT of the width T of each guide pad to the circumferential length L of the rotating shaft and the wall surface of the processed hole in an experiment in which a hole was formed using the boring cutter of the embodiment. FIG. 4 is a diagram showing a relationship between the surface roughness and the surface roughness.

[Explanation of symbols]

 Reference Signs List 21 rotating shaft 24 cutting blade 25 guide pad 26 flank 27 groove 29 guide hole T width of guide pad y width of groove D diameter of rotating shaft

Claims (6)

[Claims] 1. A cutting blade 24 is provided at a tip end of a rotating shaft 21, and a rotating shaft 2 behind the cutting blade 24 is provided.
A guide pad 25 of a required width extending in the axial direction on the outer peripheral portion of 1.
In the hole drilling tool provided with a plurality of circumferentially spaced intervals, a flank 26 is formed between the guide pads 25, and a groove along the guide pad 25 is formed at the center of each guide pad 25. 27, and each groove 2
7. A drilling tool, wherein a plurality of guide holes 29 for guiding a cutting medium are provided within a predetermined distance in a predetermined space. 2. The drilling tool according to claim 1, wherein the guide holes 29 are provided in each groove 27.
A hole drilling tool characterized in that the positions of 9 are different at least in adjacent grooves 27. 3. The hole drilling tool according to claim 1, wherein a ratio of a width y of the groove 27 to a width T of the guide pad 25 is in a range of 20 to 50%. Hole drilling tool. 4. The drilling tool according to claim 1, wherein the width (T) of the guide pad (25) is less than the width (y) of the groove (27). Ty) is in the range of 2 to 8 mm. 5. The hole drilling tool according to claim 1, wherein a circumferential length of the rotating shaft 21 is L = D.
The ratio of the total length NT (N is the number of guide pads) of the width T of each guide pad 25 to π (D is the diameter of the rotating shaft) is in the range of 30 to 50%. Hole drilling tool. 6. The hole drilling tool according to claim 1, wherein the number N of the guide pads 25 provided on the outer peripheral portion of the rotating shaft 21 is 4 or more, and the number N The circumferential length L of the shaft 21 is 0.3L / 16 ≦ N ≦ 0.5
A hole drilling tool characterized by satisfying the condition of L / 2.5.