JPH0612003U - Double-step drilling cone - Google Patents

Abstract

(57) [Summary] [Object] To provide a double-step drilling cone that can easily perform two-step drilling stepwise on a material having a two-layer structure composed of a hard layer and a soft layer. [Structure] In a double-step drilling cone in which a conical blade 2 is attached to a center drill 1 so that the position can be changed, a lower surface 5 of the conical blade is formed horizontally, and a scooping blade 6 is provided on the lower surface 5 side of the conical blade. This is a double-step drilling cone that is ground obliquely upward and is set at a position slightly higher than the lower surface 5 of the conical blade body.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a two-step drilling cone for performing two-step drilling on a building material having a two-layer structure consisting of a hard layer and a soft layer. In particular, the hard layer has a small diameter hole and the soft layer has a large diameter. The present invention relates to improvement of a double-step drilling cone that simultaneously drills holes in steps.

[0002]

[Prior art]

 As a double-step drilling cone, as shown in FIG. 1, there is known a structure in which a center drill 1 and a cone blade 2 capable of changing its position are attached on the center drill 1.

The pyramidal blade 2 is provided with a spiral chip discharge groove 3 which is hung from the side portion to the lower end, leaving the base part thereof, and an inclined scooping surface 4 is formed at the lower end end portion of the chip discharge groove 3. A scooping blade 6 is formed at the joint between the scooping surface 4 and the conical blade lower surface 5, and a claw-shaped cutting blade 7 is provided downward from the peripheral portion of the conical blade body with the chip discharging groove 3 in front of the scooping blade 6. It will be projected.

The two-stage drilling hole having the above-mentioned configuration is mainly used for two-step drilling for wood and the like, and a large-diameter hole is ablated by the cone blade 2 while the small-diameter hole is being drilled by the center drill 1. In this large-diameter hole, a claw-shaped cutting blade precedes by making a cutting line around the large-diameter hole to be machined, and the scooping blade 6 cuts the inside of this cutting line.

Therefore, in the conventional conical blade 2, in order to improve the cutting of the scooping blade 6 into the body to be perforated, as shown in FIG. 4, the lower surface 5 of the conical blade has an appropriate angle θ with respect to the horizontal plane. The scooping blade 6 that is formed at the joint between the lower surface 5 of the conical blade and the slanting scooping surface 4 is ground obliquely downward from the side of the slanting scooping surface 4 to form the conical blade body 6. It is set to be at the lowest position on the lower surface 5.

[0006]

[Problems to be Solved by the Invention] Recently, due to the diversification of building materials, in addition to wood alone, fiberboards containing plant fiber as a main raw material have been produced and used frequently.

Among these fiber boards, a wood board and a soft fiber board (insulation board), or a composite board composed of a hard fiber board (hard board) and a soft fiber board (insulation board), that is, a hard layer and Many building materials (plate materials) with a two-layer structure of soft layers are also on the market.

In using a building material having a two-layer structure of such a hard layer and a soft layer, as shown in FIG. 3, the hard layer A has a small diameter through which a fastener such as a screw nail is inserted. In the case where the hole a is bored and the soft layer B is to be machined into a large diameter hole b for embedding the head of a fastener or the like, if the conventional two-step drilling cone having the above-mentioned configuration is used, the cone blade Since the scooping blade 6 of the body 2 can also cut into the hard layer A, the operator completes the cutting of the large-diameter hole b in the soft layer B by the conical blade body 2, and When the cut moves from the soft layer B to the hard layer A when the scooping blade 6 makes an incision by judging the transfer of the cut from the layer B to the hard layer A, or when the cutting operation is intermittently performed. There is no choice but to judge from the difference in response, and there is a considerable amount of scooping blade 6 cut on the hard layer surface. In the two-step perforation for a material that is required to avoid cutting by the scooping blade 6 into the layer A as much as possible, it is difficult to perform the perforation work because it depends largely on the intuition of the operator, and the desired perforation cannot be performed. The efficiency is also low.

The present invention has been made in view of the above points, and an object thereof is to provide a two-stage drilling cone that can efficiently and easily carry out drilling work by eliminating cutting by a scooping blade into a hard layer. .

[0010]

[Means for Solving the Problems]

 The gist of the present invention for achieving the above object is to include a center drill and a conical blade attached to the center drill so that the position of the conical drill can be changed. In a double-step drilling cone in which an inclined scooping surface is formed at the lower end portion and a scooping blade is formed at the contact portion between the scooping surface and the lower surface of the conical blade, the lower surface of the conical blade is formed horizontally, and the scooping blade is Is a cone for double-step drilling, characterized in that the lower surface of the conical blade is ground obliquely upward and set to a position slightly higher than the lower surface of the conical blade.

[0011]

[Action]

 The lower surface of the conical blade is entirely pressed into the soft layer by pressing during drilling, and the scooping blade cuts into the soft layer to machine a large diameter hole. Since the lower surface of the conical blade reaches the hard layer and the pressing force at the time of punching does not push the lower surface of the conical blade into the hard layer, the lower surface of the conical blade contacts the hard layer surface and runs idle.

[0012]

【Example】

 An embodiment of the present invention will be described below with reference to the drawings.

FIG. 2 is a side view of the main part of the conical blade body of the conical drill for two-stage drilling to which the present invention is applied.

The basic structure of the two-step drilling cone to which the present invention is applied is known as described above, and the common portions are denoted by the same reference numerals and detailed description thereof will be omitted.

In the conical blade 2 of the present invention, as shown in FIG. 2, the conical blade lower surface 5 is formed horizontally so as to match the horizontal plane o. The scooping blade 6 formed at the joint between the inclined scooping surface 4 at the lower end of the chip discharge groove 3 and the lower surface 5 of the conical blade has a lower surface 5 of the conical blade by grinding the lower surface 5 of the conical blade obliquely upward. Set it to a slightly higher position.

The lower end of the cutting blade 7 is set in the same horizontal plane as the lower surface 5 of the conical blade, or is set so as to project slightly downward. Further, as the center drill 1, a well-known structure capable of drilling without distinction between the hard layer A 1 and the soft layer B 1 is used.

In the above structure, since the scooping blade is located slightly higher than the lower surface of the conical blade body, the scooping blade is large only for the soft layer in which the lower surface of the conical blade body is completely pressed by the pressing when the hole is punched. Enables machining of large holes. Therefore, since the lower surface of the conical blade does not press into the hard layer by the pressing force at the time of punching, the scooping blade does not cut into the hard layer.

Further, since the lower surface of the conical blade is formed into a flat surface, the lower surface of the conical blade contacts the hard layer surface at the time of finishing the machining of the large-diameter hole in the soft layer, so that the soft layer is in an idle state. Fall into.

[0019]

[Effect of device]

 As described above, according to the two-step drilling conical blade of the present invention, two-step perforation can be reliably performed on a building material having a two-layer structure composed of a hard layer and a soft layer without any skillful work. And, there is a feature that can be easily done.

[Brief description of drawings]

FIG. 1 is an overall side view of a two-step drilling cone.

FIG. 2 is a side view of a main part of a conical blade body of a conical drill for two-stage drilling according to the present invention.

FIG. 3 is a cross-sectional view of a two-stage perforated portion for an object to be perforated.

FIG. 4 is a side view of a main part of a conical blade body of a conventional two-step drilling cone.

[Explanation of symbols]

 1 ... Center drill 2 ... Conical blade 5 ... Conical blade lower surface 6 ... Scooping blade

Claims (1)

[Scope of utility model registration request] 1. A center drill and a conical blade attached to the center drill in a positionally changeable manner. The conical blade has an inclined scooping surface formed at a lower end portion of a chip discharge groove. In a two-step drilling cone in which a scooping blade is formed at the joint between the scooping surface and the lower surface of the conical blade, the lower surface of the conical blade is formed horizontally, and the scooping blade grinds the lower surface of the conical blade obliquely upward. A double-step drilling cone that is set at a position slightly higher than the lower surface of the cone blade.