JP6755675B2 - Circular drilling tool - Google Patents

Description

The present invention relates to an annular drilling tool, particularly a removable annular drilling tool.

A rotary drilling tool (annular drilling tool / hole saw) with an annular cutting edge is used for new holes for mounting instruments on switchboards, wiring, overuse of steel pipes, etc. (see, for example, Patent Document 1). .. The annular drilling tool cuts with a blade arranged on the peripheral portion of the cylinder, but since it is difficult to position and hold only with the blade arranged on the peripheral portion, it is located in the center of the annular drilling tool. A drill for fixing the rotating shaft (center drill) is installed to complement this. In addition, the center drill is held as close to the tip as possible in order to suppress the runout of the center drill during use.

Unlike a normal drill, the annular drilling tool does not cut the inner diameter side part, so that the required diameter can be efficiently obtained. On the other hand, in the case of the annular drilling tool, the drill cuts a small amount and discharges the tool. The inner diameter side portion is formed in a columnar shape, and remains on the inner diameter side of the annular drilling tool after penetrating the work material.

The cutting piece generated on the inner diameter side of the annular drilling tool is columnar, and it is effective to extrude it using the bottom surface to remove it, but a through hole is generated in the cutting piece coaxially with the center drill. Therefore, it is difficult for the center drill to interfere with the cutting piece, and the current situation is that there is no choice but to use the holes provided in the outer peripheral portion of the annular drilling tool to interfere. Further, since the annular drilling tool has a bottom surface portion (flange) of a cylinder due to its structure, it is difficult to extrude and remove using the bottom surface portion particularly with a small diameter.

In the conventional mechanism, the runout suppression function is secured by the relationship between the center drill through hole on the spare blade side and the center drill, but the through hole of the cutting piece generated after using the tool is the center drill through hole on the spare blade side. In addition, since it exists on the same axis as the center drill, it is difficult to remove the cutting piece using the center drill through hole on the replacement blade side.

Japanese Unexamined Patent Publication No. 6-238506

In view of the above problems, it is an object of the present invention to provide an annular drilling tool capable of ensuring the suppression of runout of the center drill when cutting a work material and easily removing a cutting piece after cutting. To do.

In order to achieve the above object, (1) the first viewpoint according to the present invention is an annular drilling tool, which is detachably attached to a shank body, and has a small diameter portion on the front end side and a thick portion on the rear end side. A center drill having a diameter portion and a spare blade having a flange portion that is detachably attached to the shank main body so as to surround the center drill and has an insertion hole through which the center drill is inserted are provided. The insertion hole is located on the tip side and is formed thicker than the small diameter portion of the center drill, and is located on the rear end side and is formed thicker than the large diameter portion of the center drill. It has a second insertion portion, and when the replacement blade is attached to the shank body, the large diameter portion of the center drill fits into the narrowest portion of the first insertion portion. To do.

(2) In the above (1), when the replacement blade is removed from the shank body toward the tip side, the small diameter portion of the center drill is located at the narrowest portion of the first insertion portion. The spare blade may be swingable with respect to the center drill within its diameter or within the range of the first insertion portion.

According to the present invention, it is possible to provide an annular drilling tool capable of ensuring suppression of runout of a center drill when cutting a work material and easily removing a cut piece after cutting.

It is an exploded sectional view of the annular drilling tool which concerns on embodiment of this invention. It is sectional drawing which shows the state which the annular drilling tool of FIG. 1 is assembled. It is a figure which shows the part of the circle A of FIG. 2 in an enlarged manner. It is sectional drawing which shows the state which the spare blade is separated from the annular drilling tool of FIG. It is a figure which shows the part of the circle B of FIG. 4 enlarged. It is a figure which shows the procedure which removes a cutting piece in the annular drilling tool which concerns on embodiment of this invention, (a) finishes cutting of a work material with the annular drilling tool assembled, and replaces a cutting piece. The figure showing the state remaining inside the blade, (b) is the state where the replacement blade is separated, and (c) is the state where the separated replacement blade is tilted and the cutting piece is replaced with the tip of the center drill outside the replacement blade. The state of being pushed out to is shown respectively. FIG. 6 is an enlarged view showing a portion of circle C in FIG. 6 (c).

Hereinafter, the annular drilling tool according to the embodiment of the present invention (hereinafter referred to as the present embodiment) will be described in detail with reference to the drawings. In addition, the same element is given the same number or reference numeral throughout the description of the embodiment.

(Structure of Embodiment)
As shown in FIG. 1, the annular drilling tool 1 according to the present embodiment can be attached to and detached from the shank main body 10, the center drill 20 detachably attached to the shank main body 10, and the shank main body 10 so as to surround the center drill 20. It is provided with an annular replacement blade 30 attached to the. Here, the shank main body 10 to which the center drill 20 is attached may be referred to as a shank assembly 40. Then, an example of those configurations will be described with reference to FIG.

In the following description, in each element constituting the annular drilling tool 1, the side of the cutting edge 211 of the center drill 20 (left side in the figure) is the tip side, and the side of the shank 11 of the shank body 10 (in the figure, the left side). The right side) will be described as the rear end side.

The shank main body 10 is fixed to an electric drill (not shown) and transmits the rotational driving force of the electric drill to the center drill 20 and the spare blade 30 attached to the shank main body 10.

The shank main body 10 includes a shank 11 that is inserted and fixed to the electric drill, and an accommodating portion 12 for accommodating the rear end side of the center drill 20 and the flange portion 31 of the replacement blade 30. Inside the accommodating portion 12, a first accommodating portion 13 into which the rear end side of the center drill 20 is inserted and a second accommodating portion 14 accommodating the adapter portion 311 of the flange portion 31 of the replacement blade 30 are provided. ..

The first accommodating portion 13 of the accommodating portion 12 is provided with a center drill locking portion 15 for detachably fixing the locking portion 221 on the rear end side of the center drill 20 on the rear end side. On the other hand, the second accommodating portion 14 of the accommodating portion 12 is provided with an adapter locking portion 16 for detachably fixing the adapter portion 311 of the flange portion 31 of the spare blade 30 on the tip end side thereof. Then, when the adapter portion 311 of the flange portion 31 of the spare blade 30 is further inserted into the second accommodating portion 14, the adapter portion 311 is pushed into the accommodating portion 12, and when the spare blade 30 is separated from the shank main body 10, the replacement blade 30 is replaced. An extrusion portion 17 for pushing the blade 30 toward the tip end is provided. The function of the extruded portion 17 will be described later.

The center drill 20 is provided at the center of the annular drilling tool 1 and complements the positioning and holding of the spare blade 30. The annular drilling tool 1 cuts the work material by the cutting blade 32 arranged on the peripheral portion of the tip cylinder of the replacement blade 30 on the work material, and the cutting blade arranged on the peripheral portion of the replacement blade 30. Since it is difficult to position and hold with only 32, the center drill 20 is also used.

Usually, a center drill having the same diameter from the tip end to the rear end is used. On the other hand, the center drill 20 according to the present embodiment has a small diameter portion 21 on the front end side and a large diameter portion 22 on the rear end side, and the diameter is configured in two stages. The function of setting the center drill 20 to two stages of diameter will be described later. A spiral cutting edge portion 211 is provided at the tip of the small diameter portion 21 of the center drill 20. As described above, the locking portion 221 fixed by the center drill locking portion 15 of the shank main body 10 is provided on the rear end side of the large diameter portion 22.

In the present embodiment, the step portion 23 of the small diameter portion 21 and the large diameter portion 22 of the center drill 20 is positioned slightly to the tip side from the center of the extension in the longitudinal direction of the center drill 20. The position of the step portion 23 may be set according to the specifications of the entire tool, which is determined based on the purpose of use, the mode of use, and the like of the annular drilling tool 1.

The spare blade 30 is for drilling a work material by cutting it in an annular shape by the rotational driving force of an electric drill. The spare blade 30 has a flange portion 31 attached to the shank main body 10 and an annular cutting blade 32 extending from the flange portion 31 toward the tip end side. The flange portion 31 is composed of an adapter portion 311 accommodated in the second accommodating portion 14 of the shank main body 10 and a bottom portion of the cutting blade 32. Individual blades (not shown) are arranged on the peripheral portion of the tip of the cutting blade 32.

Normally, the replacement blade is provided with an insertion hole having the same diameter inside the flange portion so that a center drill having the same diameter can be inserted. That is, the center drill is fitted over the entire length of the insertion hole, thereby suppressing the runout of the center drill. On the other hand, the flange portion 31 of the replacement blade 30 according to the present embodiment is provided with an insertion hole 33 divided into two portions. That is, the insertion hole 33 has a first insertion portion 331 located on the front end side and a second insertion portion 332 located on the rear end side. The first insertion portion 331 is formed in a tapered shape that tapers from the front end side toward the rear end side, while the second insertion portion 332 expands from the first insertion portion 331 and then toward the rear end side. It extends with a certain diameter. The first insertion portion 331 is not limited to the tapered shape, and may be formed in a stepped shape that opens toward the tip end side, for example, as described later as a modification.

Here, with reference to FIGS. 2 to 5, the relationship between the first insertion portion 331 and the second insertion portion 332 of the insertion hole 33 and the small diameter portion 21 and the large diameter portion 22 of the center drill 20 will be described. ..

As described above, the center drill 20 has a stepped shape in which the diameters of the small diameter portion 21 and the large diameter portion 22 are switched at an intermediate position. The narrowest portion 333, which is the rear end of the first insertion portion 331, is set to have substantially the same diameter as the large diameter portion 22 of the center drill 20, and the shank assembly 40 is assembled with the replacement blade 30. At that time, as shown in FIG. 2, they are in a mating relationship. FIG. 3 is an enlarged view of the portion of circle A in FIG. As a result, the runout of the center drill 20 can be suppressed when the annular drilling tool 1 is assembled and the work material is cut.

The narrowest portion 333, which is the rear end of the first insertion portion 331, is set to have a diameter larger than that of the small diameter portion 21 of the center drill 20 (that is, the small diameter portion 21 of the center drill 20 is set to the first insertion portion. When the spare blade 30 is separated from the shank assembly 40 (thinner than the narrowest portion 333 which is the rear end of 331), the small diameter portion 21 is located at the narrowest portion 333 as shown in FIG. Will break the mating relationship between the two. FIG. 5 is an enlarged view of the portion of circle B in FIG. As a result, after the cutting of the work material is completed by the annular drilling tool 1 and the spare blade 30 is separated from the shank assembly 40, there is a clearance between the first insertion portion 331 and the small diameter portion 21 of the center drill 20. As a result, the spare blade 30 and the center drill 20 can be tilted (swinged) with respect to each other. Since the radial direction in which the spare blade 30 and the center drill 20 are tilted with respect to each other does not matter, the tilting may be oscillated.

As will be described later, when the spare blade 30 and the center drill 20 are tilted (swinged) with respect to each other and the small diameter portion 21 of the center drill 20 comes into contact with the tapered first insertion portion 331, the center drill 20 The large diameter portion 22 of the second insertion portion 332 may be regulated by the opening 332a (see FIG. 7) at the rear end of the second insertion portion 332. This operation will be described below.

(Operation of the embodiment)
Based on the above configuration, the operation of the annular drilling tool 1 according to the present embodiment, that is, the procedure for removing the cutting piece D will be described with reference to FIGS. 6 and 7.

FIG. 6A shows a state in which cutting of the work material is completed with the annular drilling tool 1 assembled, and the cutting piece D remains inside the tip of the spare blade 30. In the case of the annular drilling tool 1, since the work material is cut in an annular shape, the donut-shaped cutting piece D whose central portion is penetrated by the center drill 20 after the work material is drilled and penetrated is the inner diameter of the spare blade 30. Generated on the side and remains.

FIG. 6B shows a state in which the spare blade 30 is separated from the shank assembly 40 in order to remove the cutting piece D. In the case of the annular drilling tool 1, since the center of the cutting piece D is penetrated by the center drill 20, when the spare blade 30 is assembled, the center drill 20 is used to remove the cutting piece D remaining inside the spare blade 30. It is difficult to remove. Therefore, the connection between the spare blade 30 and the shank main body 10 is temporarily disconnected, and the spare blade 30 is separated from the shank assembly 40.

In this separation, the extruded portion 17 provided in the shank main body 10 is utilized. That is, first, the adapter locking portion 16 is loosened to release the fixing between the replacement blade 30 and the shank main body 10. Then, the replacement blade 30 is pushed out toward the tip end side by moving the push-out portion 17 pushed into the inside of the accommodating portion 12 toward the tip end side. Note that FIG. 6B shows a state in which the extruded spare blade 30 is completely separated from the shank main body 10 by the user.

FIG. 6C shows a state in which the separated replacement blade 30 is tilted and the cutting piece D is pushed out of the replacement blade 30 by the tip of the center drill 20. In the state of FIG. 6B, for example, the tip of the center drill 20 is retracted to a position where it can come into contact with the bottom surface D1 of the cutting piece D remaining on the inner diameter side of the replacement blade 30, and then the replacement blade 30 or the center. The drill 20 is tilted so that the tip of the center drill 20 interferes with the bottom surface D1 of the cutting piece D. Then, by pressing the cutting piece D together with the spare blade 30 in the direction of the shank main body 10, the bottom surface D1 of the cutting piece D is pushed against the tip of the center drill 20, and the cutting piece D is discharged from the inside of the spare blade 30. Become.

FIG. 7 is an enlarged view of the portion of the circle C in FIG. 6 (c). Here, the small diameter portion 21 of the center drill 20 is in contact with one surface of the tapered first insertion portion 331, while the large diameter portion 22 of the center drill 20 is in the opening 332a at the rear end of the second insertion portion 332. The case of contact is shown as an example. As described later as a modification, the present invention is not limited to these modes.

Note that FIG. 6C shows a state in which the spare blade 30 is tilted upward with respect to the center drill 20 in the drawing, but the direction and degree of tilting the spare blade 30 is the direction shown in the drawing. It is not limited to. Depending on the shape of the bottom surface D1 of the cutting piece D, the diameter of the spare blade 30, and the mode of other elements constituting the annular drilling tool 1, the center drill 20 is placed in the first insertion portion 331 and the second insertion portion 332. Within the movable range, the spare blade 30 and the center drill 20 may be configured to swing in any direction with respect to each other.

(Modification example)
The annular drilling tool 1 can also be modified from the above-described embodiment as follows. That is, in the above embodiment, the first insertion portion 331 of the insertion hole 33 is formed in a tapered shape that tapers from the front end side toward the rear end side, but this may be formed in a stepped shape that opens toward the front end side, for example. In short, when the first insertion portion 331 is formed thicker than the small diameter portion 21 of the center drill 20 and is separated from the shank body 10 toward the tip side, the spare blade 30 and the center drill 20 are opposed to each other. A clearance may be formed between the first insertion portion 331 and the small diameter portion 21 of the center drill 20 so that it can swing.

By doing so, when the clearance between the first insertion portion 331 and the small diameter portion 21 of the center drill 20 is so large that the tip of the center drill 20 reaches the inside of the tip of the replacement blade 30, the replacement blade 30 is replaced. It can swing within the range of the diameter of 30 itself. Further, when the clearance between the first insertion portion 331 and the small diameter portion 21 of the center drill 20 is not large enough for the tip of the center drill 20 to reach the inside of the tip of the replacement blade 30, the replacement blade 30 is first inserted. Within the range of the portion 331, it can swing with respect to the center drill 20. Incidentally, FIGS. 6 (c) and 7 described above show an example of the latter case where the replacement blade 30 is swinging within the range of the first insertion portion 331.

Further, in the above embodiment, when the spare blade 30 is separated from the shank main body 10 toward the tip side, the large diameter portion 22 of the center drill 20 comes into contact with the opening 332a at the rear end of the second insertion portion 332. As described above, the configuration may not be in contact with each other. For example, since the diameters of the small diameter portion 21 and the large diameter portion 22 differ depending on the type of the center drill 20, the large diameter portion 22 of the center drill 20 comes into contact with the opening 332a at the rear end of the second insertion portion 332. As described above, the replacement blade 30 can swing with respect to the center drill 20 by forming a clearance between the first insertion portion 331 and the small diameter portion 21 of the center drill 20. It becomes.

(Effect of embodiment)
According to the above-described embodiment and modification, it is possible to secure the runout suppression of the center drill 20 when cutting the work material, and it is possible to easily remove the cutting piece D from the inside of the spare blade 30 after cutting. A drilling tool 1 can be provided.

Although the present invention has been described above with reference to embodiments and modifications, it goes without saying that the technical scope of the present invention is not limited to the scope described in the above embodiments. It will be apparent to those skilled in the art that various changes or improvements can be made to the above embodiments. Further, it is clear from the description of the claims that the form to which such a modification or improvement is added may be included in the technical scope of the present invention.

1 ... Circular drilling tool 10 ... Shank body 11 ... Shank 12 ... Accommodating portion 13 ... First accommodating portion 14 ... Second accommodating portion 15 ... Center drill locking portion 16 ... Adapter locking portion 17 ... Extruding portion 20 ... Center drill 21 ... Small diameter part 211 ... Cutting edge part 22 ... Large diameter part 221 ... Locking part 23 ... Step part 30 ... Replacement blade 31 ... Flange part 311 ... Adapter part 32 ... Cutting blade 33 ... Insertion hole 331 ... First insertion part 332 ... 2nd insertion part 333 ... Narrowest part 40 ... Shank assembly D ... Cutting piece

Claims (2)

An annular drilling tool
With the shank body
A center drill that is detachably attached to the shank body and has a small diameter portion on the front end side and a large diameter portion on the rear end side.
A replacement blade having a flange portion that is detachably attached to the shank body so as to surround the center drill and has an insertion hole through which the center drill is inserted is provided.
The insertion hole
A first insertion portion located on the tip side and formed thicker than the small diameter portion of the center drill,
It has a second insertion portion that is located on the rear end side and is formed thicker than the large diameter portion of the center drill.
When the replacement blade is attached to the shank body, said large diameter portion of the center drill is fitted into the narrowest portion of the first insertion portion,
The first insertion portion is formed so as to open toward the tip end side with respect to the narrowest portion.
The second insertion portion is formed so as to expand with respect to the narrowest portion.
When the spare blade is separated from the shank body toward the tip side, the small diameter portion of the center drill is located at the narrowest portion of the first insertion portion, and the spare blade is the center. An annular drilling tool characterized in that the first insertion portion and the second insertion portion are formed so as to be swingable with respect to a drill . The annular drilling tool according to claim 1, wherein the replacement blade can swing with respect to the center drill within the diameter of the replacement blade or the range of the first insertion portion.

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