JPH0727047Y2 - Hole holding mechanism for hole cutter with center drill - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a hole cutter having a center drill and a hollow piece holding mechanism for a hole saw.

[Prior Art] As a holding mechanism for a hollowed piece (chip) in a hole cutter with a center drill, the following is known.

a. A method in which a permanent magnet is installed in a hole cutter or a hole saw, and the cut-out piece is attracted to this permanent magnet.

b. A method in which the center drill is tilted by a spring to hold the hollowed piece in the hole.

c. Insert a slot near the tip of the center drill and store the blade-shaped iron plate in the slot. Hold the hollowed piece by stopping it with a spring pin so that one end of the center drill is exposed when centrifugal force is applied. Method to do.

d. In the center bit 3 to be attached to the central portion of the circular cutter blade 2, a paragraph-shaped small-diameter portion 4 is formed on the shaft portion of the center bit 3, and the thin-diameter portion 4 is formed in the body portion thereof. A center bit structure characterized in that a cylinder body 7 having a diameter larger than that of the bit and having a slit 6 formed on the side thereof is mounted (Japanese Utility Model Publication No. 61-105512).

[Problems of Prior Art] However, the above-mentioned conventional art has the following problems.

a. The method using a permanent magnet requires frequent cleaning because cutting powder adheres to this permanent magnet, reducing the holding power of the hollowed piece, which is troublesome and sharp. become worse.

b. The method of tilting the center drill has a weak holding force,
In particular, the one with a large diameter may fall into the pipe.

c. With the method of slotting, the structure of the center drill becomes complicated and it is easy to break, and the retaining function of the cutout piece is lost.

d. In Japanese Utility Model Laid-Open No. 61-105512, since the cylindrical body 7 cannot move axially (moving up and down) with respect to the bit 3, when the hollowed-out piece is held by the cylindrical body 7, All the cut-out pieces will fit (be hidden) inside the cutter blade 2. Therefore, in order to take out the cut-out piece from the inside of the cutter blade 2, it is necessary to use a tightening tool to tighten the body portion of the cylindrical body 7 to reduce the diameter, and thereby drop the cut-out piece. It is troublesome to do and use this.

It is an object of the present invention to propose a cutout piece holding mechanism that does not have the problems described in a to d above.

[Technical Means for Solving the Problems] The technical means for solving the above problems are as follows.

A small-diameter step portion having a constant width in the axial direction is formed on the upper part of the center drill blade provided at the center of the hole cutter, and the lower end of the small-diameter step portion is located below the cutting edge of the hole cutter. That is, the width is smaller than the width of the small-diameter step portion, the split groove is formed in the axial direction so that the diameter can be freely accommodated, and the outer diameter thereof is slightly larger than the outer diameter of the blade portion. A tapered taper portion that is set and that changes to a smaller diameter than the outer diameter of the blade portion is formed at the end on the blade portion side, and the inner diameter is slightly larger than the small diameter stepped portion in the converged state. A hollow cut piece holding mechanism for a hole cutter with a center drill, characterized in that an elastic cut piece holding ring is provided on the cutout piece holding ring.

In the above structure, the material of the retaining ring is preferably metal having elasticity, but may be plastic.

When the diameter is expanded (no load is applied), the outer diameter of the retaining ring should be slightly larger than the outer diameter of the blade, and its width is almost equal to the diameter of the small diameter step of the center drill. It is enough. However, this width can be made smaller when the elastic force of the retaining ring is large.

[Operation] When the retaining ring is drilled, first, when the blade portion of the center drill penetrates the pipe to be drilled and further enters, it enters into the hole drilled by this blade portion through the taper portion while the diameter is reduced. , It adheres to the inner diameter surface of the hole by its elastic action. On the other hand, the hole cutter or the hole saw starts cutting the pipe to be drilled at the same time when the retaining ring enters. At this time, the retaining ring is in close contact with the inner diameter surface of the hole of the pipe to be drilled, and the center drill idles in the retaining ring. Also, the retaining ring is
It moves upward in the small diameter step. When the cutting with the cutter or the hole saw is completed and is pulled up (retracted), the hollowed piece is held in the cutter or the hole saw by the holding ring and does not fall into the pipe. Further, the retaining ring holding the hollowed piece moves below the small diameter stepped portion due to the weight of the hollowed piece in the small diameter stepped portion. As a result, the cut-out piece is exposed from the cutting edge of the cutter or the hole saw, so that the cut-out piece can be picked up and removed by hand.

[Embodiment and Its Action] FIG. 1 shows an embodiment of the present invention. Reference numeral 1 is a hole saw, 2 is a center drill, 3 is a blade portion at the tip, 4 is a small-diameter step portion formed on the upper portion of the blade portion 3 and having a constant width (height) in the axial direction. The step portion 4 is formed by externally inserting a blade portion 3 and a spacer 2 ′ having the same diameter as the blade portion 3 onto the center drill 2. Reference numeral 5 denotes a retaining ring having a C-shaped cross section with one split groove 5 ″.
The outer diameter of the blade portion 3 is slightly larger than the outer diameter of the blade portion 3 and is made of an elastic metal body capable of converging to the smaller diameter side. Has a margin between the inner diameter and the small diameter step portion 4. Also, this retaining ring 5
At the lower end portion (on the side of the blade portion 3), a taper portion 5'which is tapered more gradually than the outer diameter of the blade portion 3 is formed. Further, the retaining ring 5 is smaller than the width of the small diameter step portion 4, and therefore,
The small diameter step portion 4 is movable in the axial direction (up and down).

In the hole saw having the above structure, the attachment portion 6 is attached to the shaft of the punching machine. Then, when piercing is started, as shown in FIG. 2, first, the blade portion 3 of the center drill 2 pierces the pipe 7 to be pierced and pierces the center hole 8. Then, when the boring further proceeds, the hole saw 1 side cuts the pipe 7 to be perforated, and at almost the same time, the retaining ring 5 enters the center hole 8 while the diameter of the retaining ring 5 is reduced via the tapered portion 5 '. This situation is shown in FIG. 3, in which the hole saw 1 is further advanced and the pipe to be drilled 7
If a hole is bored in the hole, the entry is stopped and the retaining ring 5 is brought into close contact with the inner diameter surface of the center hole 8 of the cutout piece 9 by its elastic diameter expansion action. This situation is shown in FIG. 4, and when the hole saw 1 is pulled up in this state, the hollowing piece 9 is held by the holding ring 5 and is pulled up together with the center drill 2.

Since the cutout piece 9 is vertically movable in the small-diameter step portion 4, the holding ring 5 moves to the lower part of the small-diameter step portion 4 by the weight of the cutout piece 9. As a result, the cut-out piece 9 comes out (is exposed) below the cutting edge of the hole saw 1, so that the cut-out piece can be picked up by hand and removed from the retaining ring 5.

[Effects of the Invention] As described above, the present invention has the following effects because the center drill is attached with the retaining ring that can move in the diameter and can be moved up and down, and the retaining ring holds the hollowed piece.

a. Since the hollowed piece is held at its center by the elastic action of the holding ring, the holding force is strong and there is no concern that it will fall off on the way.

b. Since the retaining ring can move up and down in the small-diameter step, the retained cutout piece is exposed from the blade edge when the hole saw or hole cutter is pulled up, so you can easily remove the cutout piece from the retaining ring by hand.

c. The retaining ring is attached to the small-diameter step of the center drill, so the structure is extremely simple and difficult to break.

d. There is no need for frequent cleaning as in the past, and the sharpness does not deteriorate.

[Brief description of drawings]

FIG. 1 is a sectional view of a hole saw embodying the present invention, and FIGS. 2 to 4 are explanatory views of the operation. 1 ... Hole saw, 2 ... Center drill 3 ... Blade part, 4 ... Small diameter step part 5 ... Holding ring, 6 ... Mounting part 7 ... Punched pipe, 8 ... Center hole 9 ... Cutout piece

Claims (1)

[Scope of utility model registration request] 1. A small-diameter stepped portion having a constant width in the axial direction is formed on an upper portion of a blade portion of a center drill provided at the center of the hole cutter, and a lower end of the small-diameter stepped portion is formed from a cutting edge of the hole cutter. Is also located at the lower part, and has a width smaller than that of the small-diameter step portion, and is configured to form a split groove in the axial direction so that the diameter can be freely accommodated, and the outer diameter is the outer diameter of the blade portion. Is set slightly larger than the diameter of the blade, and a tapered portion is formed at the end of the blade that changes to a smaller diameter than the outer diameter of the blade. An elastic hollowing piece retaining ring is provided which is formed in a slightly larger state, and the retaining ring is attached to the small diameter stepped portion. One-sided holding mechanism.