JP2000334636A - Dustproof cover and manufacture thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a dustproof cover corresponding to the length of a tool at low cost by forming a cylindrical dustproof cover covering the surrounding of a drilling tool out of a flexible material and connecting bellows cylindrical bodies each other having ruggedness of substantially the same pitch each other in the axial direction by overlapping projecting and recessing parts of end parts each other. SOLUTION: A dustproof device is constituted of a base part constituted of an inside cylinder, an outside cylinder, a bearing and a base end wall and a dustproof cover 60. The dustproof cover 60 is integrally formed of materials easy to be elastically deformed and has a size to cover the whole of a body from the outside. Bellows cylinders 62, 63 extendible and contractible in the axial direction are connected by being overlapped each other and are made to have a prescribed length. At a tip of the bellows cylindrical body 62 on the tip side, a doughnut plate-shaped tip wall 64 is formed. At a rear end of the bellows cylindrical body 63 on the rear side, a cylindrical mounting part 66 projecting in the axial direction is formed. As a result, the dustproof cover corresponding to the length of a tool can be obtained at low cost.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dustproof cover used for a drilling tool for drilling a hole in a wall or other workpiece and a method of manufacturing the dustproof cover.

[0002]

2. Description of the Related Art Conventionally, as a dustproof device used for a drilling tool, for example, one disclosed in Japanese Utility Model Laid-Open No. 6-85771 is known. The dustproof device according to the publication includes a bellows-shaped cylinder (dustproof cover) 5 and a mounting body 9 connected to a base end of the cylindrical body 5. (Part holding drill bit 4) 2
It is designed to be removably attached to. According to the dustproof device, when drilling work with the drill bit 4, the cylindrical body 5 contracts as the drilling work progresses and the cylindrical body 5 covers the drill bit 4 from beginning to end, which is generated by the drilling work. Dust can be prevented from scattering to the outside.

[0003]

If the dust-proof cover is too long compared to the drill bit 4, the dust-proof cover hits the wall before the drill bit 4 starts drilling, so that the drill bit can be centered. On the contrary, if the dust cover is too short, the dust cover cannot reach the wall surface only after the drilling by the drill bit 4 has progressed considerably, so that sufficient dust protection cannot be achieved. Therefore, it is preferable that the length of the dust-proof cover is suitable for the length of the drilling tool.

[0004] However, the length of the drilling tool varies, and if various types of dust-proof cover molding dies are to be manufactured in accordance with the lengths, the cost of the dies is extremely high and the mass productivity is reduced. Therefore, a significant increase in costs cannot be avoided.

[0005] In view of such circumstances, an object of the present invention is to provide a dust-proof cover that can be provided at a low cost according to the length of a tool and a method of manufacturing the dust-proof cover.

[0006]

As a means for solving the above-mentioned problems, the present invention relates to a cylindrical dust-proof cover for covering the periphery of a drilling tool, which is made of a flexible material and has substantially the same pitch as each other. The bellows cylinders having the irregularities are connected in the axial direction by overlapping the irregularities at the ends thereof.

[0007] The method of the present invention is a method for manufacturing a cylindrical dustproof cover for covering the periphery of a drilling tool, wherein bellows cylindrical bodies made of a flexible material and having irregularities at substantially the same pitch are formed at their ends. By overlapping the concaves and convexes of the portions in the axial direction, a dustproof cover having a desired length is obtained.

According to the present invention, the dust-proof cover having a desired overall length can be obtained by simply connecting the end of one bellows cylinder to the end of the other bellows cylinder. Can be At this time, since the bellows cylindrical body has flexibility, it is possible to easily overlap the concaves and convexes at the ends. In addition, once the cylinders are connected, the cylinders are mutually restrained by the fitting of the concavities and convexities. Therefore, even if the dustproof cover expands and contracts during the drilling operation, a positional displacement occurs between the bellows cylinders in the length direction. hard. In addition, it is possible to obtain a dust-proof cover of a desired length by dividing a plurality of molded products having the same shape formed by one type of mold and connecting them appropriately, so that it is not necessary to prepare many types of molds. Thus, the cost can be significantly reduced.

For example, in the method for manufacturing a dustproof cover according to the present invention, a single bellows cylinder may be divided on the way, and the divided cylinders may be connected to each other. In this way, the overall length can easily be made shorter than the original length. Further, the total length can be easily adjusted depending on the size of the overlapping area.

In the method for manufacturing a dustproof cover according to the present invention, the bellows-shaped cylindrical body is formed such that one end is formed as a contact portion with a surface to be bored and the other end is formed as a mounting portion to a tool. Then, the divided cylinders may be connected to each other by overlapping the concaves and convexes at the ends on the divided side. With this configuration, both ends formed as the contact portion and the attachment portion can be left as they are as the both ends of the divided cylinders connected to each other, and the same contact and attachment properties as the preformed bellows cylinder can be obtained. Can be secured.

In the method for manufacturing a dustproof cover according to the present invention, two bellows cylinders having the same shape are prepared, and one bellows cylinder is divided in the middle, and one of the divided cylinders is divided into: You may connect with the other prepared bellows cylinder. In this way, the overall length can be easily adjusted (generally longer) by setting the dimension to be divided and the overlap size.

In the method of manufacturing a dustproof cover according to the present invention, two bellows cylinders having the same shape are prepared, both bellows cylinders are cut in the middle, and one of the bellows cylinders is cut off. The tubular body and one of the divided tubular bodies of the other bellows tubular body may be connected by overlapping the ends on the respective divided sides.

In this case, the total length can be easily made longer or shorter by considering the length of the overlapping portion.

In the method for manufacturing a dustproof cover according to the present invention, the two bellows cylinders each having one end formed as a contact portion with a surface to be bored and the other end formed as a mounting portion to a tool. One of the two divided cylinders that are used and connected may have a contact portion on one side, and the other may have an attachment portion on the other side to connect the two divided cylinders. In this way, with the contact portion and the mounting portion at both ends,
The length can be easily increased or decreased.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described with reference to the drawings.

The drilling tool shown in FIG. 1 and FIG.
0, and a drive connecting portion 12 fixed to a base end (right end in FIGS. 1 and 2) of the main body 10, and these form a tool main body. Tip of main body 10 (left end in the figure)
A center drill 14 and a body 16 are coaxially mounted on the main body 10, the main body 10, the center drill 14,
And a boring tool body composed of the body 16 is integrally rotated and driven.

As shown in FIGS. 3 (a) and 3 (b), a circular mounting hole 18 is provided at the tip of the main body 10 along the center axis as a mounting portion of the center drill 14. An insertion hole 20 having an irregular cross section is provided at the back of the mounting hole 18.
Are formed. The center drill 14 has a drill portion 22 at the distal end, and the mounting hole 1 at the proximal end.
8 has a round shaft-shaped mounting portion 24 inserted therein. At the end of the mounting portion 24, an insertion portion 26 having a modified cross-sectional shape to be fitted into the insertion hole 20 is formed. . And
The fitting of the insertion section 26 and the insertion hole 20 having the irregular cross section prevents the rotation of the center drill 14.

A circumferential groove 28 is formed in the middle of the mounting portion 24 over the entire circumference, and a locking portion 30 for locking the circumferential groove 28 is formed in a portion of the main body 10 around the mounting hole 18. Is provided. Specifically, through holes 32 extending from the outer peripheral surface to the mounting holes 18 are provided at a plurality of locations in the circumferential direction of the main body 10.
A ball 34 having a diameter that fits with the ball 8 is inserted.

On the other hand, a cylindrical operating member 36 which covers the through hole 32 over the entire circumference is externally fitted to the portion where the through hole 32 is formed. The rear end of the operation member 36 (FIG. 3A)
An operating flange 36a is formed at the right end (in (b)), and a concave groove 36b is formed over the entire circumference at an appropriate position on the inner peripheral surface. A concave portion 36c is formed in the front inner side surface of the operating member 36, and a compression coil spring 38 is loaded therein.

The front end of the compression coil spring 38 is
0, and the rear end thereof abuts against the inner wall of the concave portion 36c. The resilient force of the compression coil spring 38 causes the operating member 36 to move rearward (see FIG. 3).
(A) and (b) in the right direction. By this resilient force, the operating member 36 is normally held at the retracted position where the rear end (right end in the figure) of the operating member 36 hits the step portion 10a of the main body 10 as shown in FIG. The inner peripheral surface of the operating member 36 pushes the ball 34 inward to engage with the circumferential groove 28 of the center drill 14, while the operating member 36 is pressed from the state shown in FIG. By sliding forward in opposition,
As shown in FIG. 3B, the concave groove 36b of the operating member 36 matches the arrangement position of the ball 34, and as a result, the ball 3
4 escapes into the concave groove 36b so that the engagement with the peripheral groove 28 can be released.

As shown in FIG. 2, the body 18 comprises a donut plate-shaped base wall 40 and a body 42 extending axially from the outer periphery of the base wall 40. A number of blades 44 are arranged side by side along the circumferential direction. A female screw 46 and a male screw 48 are formed on the inner peripheral surface of the base end wall 40 and the outer peripheral surface of the distal end portion of the main body 10, respectively.
Are fixed to the main body 10. In this state, the center drill 14 is located on the central axis of the body 16 and the drill portion 22 projects to the tip side (left side in FIGS. 1 and 2) from the tip blade of the body 16. .

In this embodiment, a center portion of the center drill 14 is provided with a flange 15 having a diameter larger than that of the other portion.
By extracting the swarf, the chips accumulated inside the body 16 can be easily pulled out of the body 16 by the flange portion 15.

Next, a dustproof device 50 for covering the drilling tool is provided.
Will be described.

The dustproof device 50 includes a base including an inner tube 52, an outer tube 54, a bearing 56 and a base end wall 58, and a dustproof cover 60.

As shown in FIG. 3 and FIG.
Are fitted directly to the outside of the rear part of the main body 10. A screw hole 52a is provided at an appropriate position of the inner cylinder 52 so as to penetrate the inner cylinder 52 in the radial direction.
The inner tube 52 is fixed on the outer peripheral surface of the main body 10 by screwing the 3. When the screwing of the set screw 53 is completed, the head of the set screw 53 projects radially outward from the outer peripheral surface of the inner cylinder 52.

The outer cylinder 54 is fitted outside the inner cylinder 52. The outer cylinder 54 is provided with a through-hole 54b penetrating the outer cylinder 54 in the radial direction. As shown in FIG. 4, the through-hole 54b has an oval shape extending in the tool axis direction, and the projecting head of the set screw 53 is fitted into the through-hole 54b. By this fitting, the inner cylinder 5
Although the relative rotation of the outer cylinder 54 with respect to 2 is restricted, the outer cylinder 54 can slide in the axial direction with respect to the inner cylinder 52 by a stroke corresponding to the axial length of the through-hole 54b. ing.

An operating portion 54a is formed at the front end of the outer cylinder 54 to protrude radially inward. This operation unit 54
“a” can contact the rear end face of the operation member 36 from the rear in front of the inner cylinder 52. Then, in a state in which the outer cylinder 54 is advanced most than the inner cylinder 52, the operating portion 54a of the outer cylinder 54 pushes the operating member 36 forward, as shown in FIG. Is configured to slide the operation member 36 to a position that matches the ball 34.

The bearing 56 is interposed between the outer peripheral surface of the outer cylinder 54 and the inner peripheral surface of the base end wall 58.
4 and the base end wall 58 are connected so as to be relatively rotatable. The base end wall 58 has a ring shape and a dustproof cover 60
Is installed.

The dust cover 60 is integrally formed of a material (for example, synthetic resin (to be described in detail later)) which is relatively easily elastically deformed, and has a size to cover the entire body 16 from the outside. More specifically, as shown in FIGS. 5 (a), 5 (b) and 6, the bellows cylinders 62, 63 which can be extended and contracted in the axial direction are partially overlapped and connected to each other to have a predetermined length. A donut plate-shaped tip wall 64 is formed at the tip (the left end in FIG. 5A) of the bellows cylinder 62 on the front side, and the bellows cylinder 6 on the rear side is formed.
At the rear end of 3, a cylindrical mounting portion 66 protruding in the axial direction is formed.

The mounting portion 66 has an inner diameter that can be fitted to the outside of the base end wall 58, and a plurality of (three in the illustrated example) projections (projections) 68 are formed on the inner peripheral surface. ing. These projections 68 have a constant width in the circumferential direction.

On the other hand, a plurality of insertion recesses 58a as shown in FIGS. 7 and 8 are formed in the outer peripheral portion of the base end wall 58. These insertion recesses 58a are formed at positions corresponding to the protrusions 68, and have a shape such that the protrusions 68 can be inserted from the front end side (left side in FIG. 7B) with almost no gap. Further, an insertion groove 58b extends in the circumferential direction from the insertion depth of each insertion recess 58a,
By rotating the dustproof cover 60 at the stage where the projections 68 are inserted to the depths of the respective insertion recesses 58a and allowing the respective projections 68 to enter the insertion grooves 58b, the respective projections 68 do not come out of the insertion recesses 58a (that is, from the base end wall 58). Dustproof cover 60
Will not come off). That is, the dust cover 60 is detachably attached to the base end wall 58.

The insertion recess 58a and the insertion groove 58b
A slight protrusion 58c is provided at the boundary between the two.
The projection 58c prevents the projection 68 having entered the insertion groove 58b from easily returning to the insertion recess 58a.

Next, how to handle the drilling tool and the dustproof device 50 will be described.

The main body 10 is fitted with the drive connecting portion 12, the drill bit 14, and the body 16.

The entire dustproof device 50 is mounted on the main body 10. Specifically, at the axial position (the position in FIG. 3A) where the operation portion 54a of the outer cylinder 54 is sandwiched between the rear end of the operation member 36 at the retracted position and the inner cylinder 52, Is fixed with a set screw 53. Since the dustproof device 50 is mounted on the tool main body side, not on the rotary drive side for rotating the tool, even when the drive connecting portion 12 is connected to any type of rotary drive, The dustproof device 50 can be used in common.

The drive connection unit 12 is connected to a rotary drive (not shown), and presses against a workpiece such as a wall while rotating the entire tool at high speed. As a result, first, the drill portion 22 of the center drill 14 drills and performs positioning, and then the periphery of the drill is ground by the tip blade of the body 16, so that a hole having substantially the same diameter as the body 16 is finally formed on the workpiece. Drilled in. At this time, the front end wall 64 of the dustproof cover 60 contacts the front surface of the workpiece, and the dustproof cover 60 shrinks as the processing progresses, so that the dustproof cover 60 always surrounds the processing area.
And dust is prevented from being scattered to the outside.

Next, a method of manufacturing the dustproof cover 60 for preventing the scattering of dust to the outside will be described.

FIG. 9 shows a bellows cylinder of a fixed length which is extensible and flexible and which is formed by using a mold.
The bellows cylinder 61 has eight large-diameter portions A and nine small-diameter portions B, and is shorter than the body 16 having the length shown in FIG. Therefore, the body 16 shown in FIG. 1 cannot be covered and concealed sufficiently, and cannot perform the dustproof function at the beginning of the drilling operation.

Therefore, in this embodiment, two bellows cylinders 61 each having eight large-diameter portions and nine small-diameter portions B shown in FIG. 9 are used, and the middle of both bellows cylinders 61 is cut off, as shown in FIG. As shown in the figure, one of the bellows cylinders 61 has a split cylinder on the front side (5 large-diameter portions).
62 and a rear dividing cylinder body (six large-diameter portions) 63 of the other bellows cylinder body 61 are connected by overlapping the dividing side,
It has ten large diameter parts. The front-side split cylinder body (five large-diameter portions) 62 has a donut plate-shaped tip wall 64 at the tip.
And the rear split cylinder 63 has a mounting portion 66 at the rear end. The overlapping portion is one mountain. That is, the large diameter portion A at the end and the two small diameter portions B on both sides thereof are present. When one ridge is overlapped in this way, the connection between the two divided cylinders 62 and 63 is made strong by the fitting of the irregularities, and it is difficult for the two divided cylinders 62 and 63 to come off during the expansion and contraction operation accompanying the drilling operation. it can. When the rigidity of the bellows cylinder 61 is taken into consideration, the overlapped portion may be half a mountain or one and a half or more.

Therefore, when the dust cover 60 connected in this manner is used, the body 16 is completely covered and concealed as shown in FIG. Dust prevention can be performed effectively from the beginning. Conversely, if the dust cover 60 is too long, the center drill 14 will be completely covered and concealed, making it difficult to align the center.
The length of 0 is preferably in an appropriate length range. For this reason, the lengths of the two divided cylinders 62 and 63 and the length of the overlapping portion (the number of the large-diameter portion A and the small-diameter portion B) are appropriately adjusted.

In the present embodiment, the bellows cylinder 61 which is manufactured by using a mold and has a predetermined length and is formed in advance.
It is not necessary to prepare bellows cylinders formed in various lengths in advance, that is, expensive molds for such bellows cylinders are prepared for each length size. There is no need to do so, and it is possible to achieve a significant cost reduction. Along with this, it is possible to cope with a case in which bodies of various lengths are replaced and used.

Further, since it is necessary to perform an operation of superposing the two divided cylinders 62 and 63, the material of the dustproof cover 60 is as follows.
Flexibility is required. However, it is also required to reduce freely during the drilling operation and return to a predetermined length after the operation. As such a material, it is preferable to use a polyolefin resin such as polyethylene and polypropylene. In this embodiment, high-pressure polyethylene is used.

In the above-described embodiment, a case is described in which a dustproof cover having 10 large-diameter portions is manufactured using two bellows cylinders having 8 large-diameter portions and 9 small-diameter portions. Is not limited to this.

For example, as shown in FIG. 10A, the middle of a bellows cylinder 100 (similar to 61) having eight large-diameter portions and nine small-diameter portions is divided (indicated by a dashed line). Tip wall 1
10a, and a cylindrical body 102 having an attachment portion 102b. As shown in FIG.
01 and 102 are connected by overlapping their divided ends. In this case, you can easily shorten the overall length,
In addition, the total length can be freely set depending on the degree of overlap. Further, both ends of the bellows cylindrical body 100 (the tip wall 101).
a and the mounting part 102b) can also be left.

As shown in FIG. 11 (a), two bellows cylinders 103 and 104 (both having the same structure as 61) having eight large-diameter portions and nine small-diameter portions are prepared. A cylinder 105 having a distal end wall 104a which is cut off (shown by a dashed line) on the way, and a cylinder 106 having an attachment portion 104b
As shown in FIG. 11B, one of the cylindrical members 105
To the end of the other bellows cylindrical body 103 (the tip wall 10
3a). In this case, the total length can be easily increased, and the distal end wall 104a and the mounting portion 103b can be present at both ends of the connected components. The divided cylinder 106 is connected to the other bellows cylinder 1
03 may be connected to the rear end.

Further, as shown in FIG. 12 (a), two bellows cylinders 107 and 108 (same as 61) having eight large diameter parts and nine small diameter parts are prepared. Body 107
In the middle (indicated by a dashed line), and
And a cylindrical body 109 having a mounting portion 107b, and the other bellows cylindrical body 110 is divided (shown by a dashed line) in the middle to form a cylindrical body 111 having a tip wall 110a. As shown in FIG. 12 (b), a cylindrical body 112 having a portion 110b is connected, and the longer one of the cylindrical bodies 108 and 112 is connected. In this case, the total length can be easily increased. The dustproof cover of FIG.
It was obtained in this way. Although not shown, the divided short cylinders 109 and 111 may be connected to each other. In this case, the overall length can be easily reduced. When the connection is performed as shown in FIG. 12, in a state where the tip wall 107a (or 110a) and the mounting portion 110b (or 107b) are present at both ends.
It is easy to manufacture a long or short product.

In the above description, the case where the dustproof cover is manufactured by using the bellows cylinder having eight large-diameter portions and nine small-diameter portions is described as an example. Not limited,
Even when a bellows cylindrical body having two or more large-diameter portions and small-diameter portions is used, it can be similarly applied and manufactured.

Further, in the present invention, three or more bellows cylinders formed in advance with a predetermined length may be used, and these may be connected as they are or by dividing one or more of them. .

Also, a large number of bellows cylinders for the front end having only the front end wall (64 etc.) at one end and a bellows cylinder for the rear end having only the mounting portion (66 etc.) at one end are formed. Alternatively, the bellows cylindrical body for the front end may be directly or divided, and the bellows cylindrical body for the rear end may be directly or divided, and both may be connected. Also in this case, dustproof covers having various overall lengths can be formed using only two types of molds.

Although not explicitly stated in the above description, the bellows cylindrical body of the dustproof cover according to the present invention is not limited to the case where the cross-sectional shapes of the small diameter portion and the large diameter portion are triangular, but may be corrugated. Of course, it may be possible.

Further, in the above embodiment, the length of the bellows cylindrical body which is a molded product is shorter than the length of the replaceable body, and the dustproof cover using the bellows cylindrical body as it is covers the body. Although the case where the cover cannot be hidden has been described as an example, the present invention can be similarly applied to a drilling tool other than the body (for example, only a drill).

In the present invention, when the base and the dust cover are configured to be detachable, the specific structure is not limited to the one shown in the drawing, but may be any as long as it is detachable.
For example, a projection is provided on the outer peripheral surface of the main body 10, an insertion recess in which the projection is inserted in the axial direction on the mounting portion 66 side of the base end of the dustproof cover 60, and an insertion extending in a circumferential direction from a deep portion of the insertion recess. A groove may be formed.

[0053]

As described above, according to the present invention, the end of one bellows cylinder (including the split cylinder) is overlapped with the end of the other bellows cylinder (including the split cylinder). Can be easily connected with each other, and as a result, it is possible to obtain the desired overall length. In addition, it is sufficient to cut and use a large number of formed bellows cylinders, and prepare other types of molds This eliminates the need to carry out the work, and a tool that is appropriate for the length of the tool can be obtained at low cost.

[Brief description of the drawings]

FIG. 1 is a partially sectional front view showing a state in which a dustproof device is attached to a drilling tool in an embodiment of the present invention.

FIG. 2 is a partially sectional front view showing the drilling tool.

FIG. 3A is a cross-sectional front view showing a state where a center drill is locked on the main body side of the drilling tool, and FIG. 3B is a cross-sectional front view showing a state where the lock is released. .

FIG. 4 is a plan view showing a locking portion of the drill bit.

FIG. 5A is a front view of a dust cover in the dustproof device, and FIG. 5B is a side view.

FIG. 6 is a sectional view of the dustproof cover shown in FIG.

7A is a side view of a base end wall of the dustproof cover, FIG. 7B is a front view of the base end wall, and FIG.
It is a C line sectional view.

8A is a cross-sectional view taken along line AA of FIG. 7B, FIG.
FIG. 8 is a sectional view taken along line BB of FIG.

FIG. 9 is a cross-sectional view showing a bellows-shaped cylindrical body used for manufacturing the dustproof cover according to the embodiment of the present invention, which is manufactured by using a metal mold.

FIG. 10 is an explanatory view showing one example of a method for manufacturing a dustproof cover according to the method of the present invention.

FIG. 11 is an explanatory view showing another example of a method for manufacturing a dustproof cover according to the method of the present invention.

FIG. 12 is an explanatory view showing still another example of the method for manufacturing the dustproof cover according to the method of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 10 Main body (tool main body) 12 Drive connection part (tool main body) 14 Center drill 16 Body 50 Dustproofing device 60 Dustproof cover 62, 63 Minute cylinder 64, 101a, 103a, 104a, 107a, 11
0a Tip wall 66, 102b, 103b, 104b, 107b, 11
0b Mounting part 68 Projection (projection part)

Claims (7)

[Claims] 1. A cylindrical dust cover for covering the periphery of a drilling tool, wherein a bellows cylindrical body made of a flexible material and having irregularities of substantially the same pitch is overlapped with irregularities at its ends. A dustproof cover characterized by being axially connected together. 2. A method of manufacturing a cylindrical dustproof cover for covering the periphery of a drilling tool, comprising: forming a bellows cylindrical body made of a flexible material and having irregularities of substantially the same pitch with each other; Connected in the axial direction by overlapping each other,
A method for producing a dustproof cover, wherein a dustproof cover having a desired length is obtained. 3. The method for manufacturing a dustproof cover according to claim 2, wherein a single bellows cylinder is divided in the middle and the divided cylinders are connected to each other. 4. A bellows cylinder body having one end formed as a contact portion with a surface to be bored and the other end formed as a mounting portion to a tool, and the divided cylinders are separated from each other. The method for manufacturing a dustproof cover according to claim 3, wherein the connection is performed by overlapping the concave and convex portions at the ends on the dividing side. 5. Two bellows cylinders having the same shape are prepared,
3. The method for manufacturing a dustproof cover according to claim 2, wherein one of the bellows cylinders is divided on the way, and one of the divided cylinders is connected to the other bellows cylinder prepared. 6. Two bellows cylinders having the same shape are prepared,
Both bellows cylinders are cut in the middle, and one of the split bellows in one bellows cylinder and one of the split bellows in the other bellows cylinder are separated from each other on the cutting side. The method for manufacturing a dustproof cover according to claim 2, wherein the dustproof cover is connected by overlapping. 7. The two bellows cylinders having one end formed as a contact portion with a surface to be bored and the other end formed as a mounting portion to a tool, and are connected to each other. 7. The method for manufacturing a dustproof cover according to claim 6, wherein one of the cylinders has a contact portion, and the other has a mounting portion, and the two divided cylinders are connected to each other.