JPS6128656Y2 - - Google Patents

Description

[Detailed description of the invention] The present invention has a cylindrical rotary blade body in which a cutting blade part discontinuous in the circumferential direction is formed on the periphery of the tip, and a conical part of the tip protrudes beyond the cutting blade part. a center drill that is rotatable as a unit, and a maximum diameter portion of the tip conical portion having a small spiral protrusion on the circumferential surface is formed to have a larger diameter than a portion continuous to the proximal end side of the center drill. And,
A drilling machine, in particular, a center drill, in which the small spiral protrusion is formed so that its entirety passes through the cut piece by drilling, and a tapered part is formed adjacent to the tip side of the maximum diameter part. The present invention relates to an improvement in a center drill which is formed so that the rotational resistance of the center drill is made as small as possible so that drilling work can be performed easily and cut-off pieces can be easily collected.

Conventionally, as shown in Japanese Patent Publication No. 52-7197, for example, the maximum diameter part with a small spiral protrusion to prevent the cut piece from falling off and the tapered part at the tip of the cylindrical rotary blade were It was arranged to protrude greatly from the cutting edge.

However, when the maximum diameter part of the hole is cut into the workpiece, the cylindrical rotary blade does not act on the workpiece, and the center drill, which is thin and weak in strength, is There was a risk that a large bending force would be applied due to the cutting reaction force on the protrusion, and there was a drawback that the center drill was likely to be damaged.

An object of the present invention is to effectively prevent damage to the center drill while maintaining good functionality for facilitating drilling work and recovery of cut pieces.

The characteristic configuration of the present invention is that the cutting blade part of the cylindrical rotary blade body has a small spiral protrusion that allows the cut piece to pass through, and the entire maximum diameter part that is larger than the center drill part that continues on the proximal end side. This is because the center drill is arranged in substantially the same phase in the longitudinal direction of the center drill, and its effects are as follows.

In other words, when drilling a hole, the tapered part of the tip of the center drill is cut into the workpiece to be drilled and positioned, and the cylindrical rotary blade is cut into the workpiece at almost the same time as the maximum diameter part is cut into the workpiece. Therefore, the bending of the center drill caused by the cutting reaction force against the small spiral protrusion can be eliminated or reduced by the supporting action of the cylindrical rotary blade.

And, since the width of the maximum diameter part in the longitudinal direction of the center drill is formed to be extremely small,
By making the contact area of the small spiral protrusion and the maximum diameter part with the part to be drilled sufficiently small, the resistance to the cutting of the center drill can be sufficiently small, making the drilling work easy, and cutting with the rotating cylindrical blade. The helical small protrusion and the maximum diameter part can be passed through the member to be drilled before the cutting is completed, or almost simultaneously with the completion of the cutting, and the cut piece cut by the cylindrical rotary blade body can be It can be reliably locked and recovered depending on the part.

As a result, with an extremely simple modification that simply involves changing the arrangement of the largest diameter part, it has become possible to not only facilitate drilling work and recover cut-off pieces, but also to effectively prevent damage to the center drill. This has made it possible to obtain drilling machines with excellent performance and durability.

Next, an example will be shown with reference to FIGS. 1 and 2.

1 is a cutting edge portion 1 that is discontinuous in the circumferential direction on the tip periphery;
It is a cylindrical rotary blade body having a shape a, and is connected to a rotary shaft 3 via a bolt 4 so as to be detachably rotatable together with a center drill 2 disposed at its rotary shaft core. Reference numeral 2a denotes a conical part formed at the tip of the center drill 2, and the conical part 2a is applied to a member to be drilled, for example, a conduit A, in advance of the cutting blade part 1a to determine the drilling position. The structure is such that centering can be performed.

In the tip conical portion 2a, a maximum diameter portion 2c having a small spiral protrusion 2d on the circumferential surface for preventing the cut piece from falling off and a tapered portion 2a' at the tip for centering are formed adjacent to each other, and The boundary between the maximum diameter portion 2c and the tapered portion 2a' is arranged at approximately the same position in the longitudinal direction of the center drill 2 with respect to the cutting edge portion 1a, and the entire maximum diameter portion 2c is formed short, thereby cutting. Center drill 2 for the blade part 1a
are arranged in substantially the same phase in the longitudinal direction.

Reference numeral 5 denotes a lid which holds the rotary shaft 3 in an eccentric position so as to be rotatable and slidable in a sealed state, and a feed screw 7 for the rotary shaft 3 is screwed onto the upper end of an upright arm 6. 8 is a rotary operation handle with a ratchet that is engaged with the upper end of the rotary shaft 3. 9 is
It is a cylinder into which the lid 5 is rotatably fitted in a sealed state, and the lid 5 can be fixed with bolts 10. 11 is attached to both sides of conduit A in a sealed state,
It is a split joint consisting of a pair of cylindrical bodies 12 and 12 whose overhanging flanges can be tightened with bolts and nuts, and the tube 9 is sealed with bolts 14 to a cylindrical part 13 that is integrally erected on one of the cylindrical bodies 12. Fixed.
Further, a shutter 15 for opening and closing the internal passage is slidably attached to the cylindrical portion 13 in a sealed state.

It should be noted that the specific structure of the drilling machine described above is merely an example, and the present invention is not limited thereto, and the object of drilling is not limited to conduits in uninterrupted flow construction.

[Brief explanation of the drawing]

The drawings show an embodiment of the drilling machine according to the present invention, and FIG. 1 is an overall longitudinal sectional front view, and FIGS. 2 A and 2 B are enlarged longitudinal sectional views of the main parts. 1... Cylindrical rotary blade body, 1a... Cutting blade portion, 2...
...Center drill, 2a... Tip cone, 2c...
Maximum diameter part, 2d...Spiral small projection.

Claims (1)

[Scope of utility model registration request] A cutting edge portion 1a discontinuous in the circumferential direction on the tip periphery
A center drill 2 having a conical end portion 2a protruding beyond the cutting edge portion 1a is integrally provided on the rotation shaft core portion of the cylindrical rotary blade body 1 in which a conical tip portion 2a is formed. The maximum diameter portion 2c having the small helical protrusion 2d on its circumferential surface is formed to have a larger diameter than the portion continuous to the proximal end side of the center drill 2, and the entire spiral small protrusion 2d is The drilling machine is provided with a hole formed so that the cut piece passes through, and a tapered portion 2a' is formed adjacent to the tip side of the maximum diameter portion 2c, and the entire maximum diameter portion 2c is The drilling machine is arranged in substantially the same phase with respect to the cutting edge portion 1a in the longitudinal direction of the center drill 2.