JP2001009618A - Boring tool - Google Patents

Abstract

PROBLEM TO BE SOLVED: To form a hole, too large to form a hole by a drill alone without adhering chips and cut disc to a piercing body for centering and besides generating burrs at the lower edge of a hole, in a synthetic resin plate through automation. SOLUTION: A tool comprises a cylinder blade body 1 provided at a cylinder end with a cutting edge 11; and a piercing body 2 for centering having a pointed part 21 concentrically situated in the cylinderical blade body 1 and further protruding axially externally than the cutting edge 11 and piercing a synthetic resin plate. This constitution prevents adhesion of chips and a cut disc to the piercing body 2 with generating chips by the piercing and forms a hole free from burrs and automates boring.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a drilling tool for drilling a hole of a size that cannot be drilled by a drill alone into a material to be drilled such as a synthetic resin plate.

[0002]

2. Description of the Related Art When a synthetic resin product is provided with a hole having a size that cannot be drilled alone (for example, a hole of 13 to 40 m / m), it is generally provided by a molding die in a molding step of molding the synthetic resin product. Can be For this reason, a drilling tool for continuously drilling holes of the above-described size in a synthetic resin plate has not been developed.

[0003] When a hole having the above-mentioned size is made in a synthetic resin plate, it is conceivable to use a drilling tool used for making a hole in a metal plate.

FIG. 7 is a sectional view showing a drilling tool used for drilling a metal plate. The drilling tool is fixed with a cylindrical blade body 101 having a blade 100 at a cylindrical end, and a screw body 110 in the cylindrical blade body 101 so as to be concentric and integrally rotatable,
Blade 1 protruding outward in the axial direction from blade 100 at the shaft end
02 and the base of the drill 103 in the cylindrical blade body 101 are fitted and held, and elastically press the disc-shaped chips generated by drilling of the drill 103 and the cylindrical blade body 101. A substantially conical coil spring 120 is provided so that the drill 103 drills a centering hole at the center of the drilling position, and the cylindrical blade body 101 drills a hole of the aforementioned size.

[0005] The cylindrical blade body 101 has a plurality of blades 100 at one cylindrical end at appropriate intervals in the circumferential direction, and a bottomed cylindrical portion 104 having a bottom at the other cylindrical end; A cylindrical holding portion 105 protruding outward at the center of the bottom of 104;
It has a mounting shaft portion 106 that is continuous with the edge of the holding portion 105 and a chip discharge hole 107 that extends in the axial direction from one cylinder end provided with the blade 100 to the other cylinder end. The holding portion 105 is provided with a screw hole 109 which is opened in a hole at the center thereof. The drill 1 is tightened by screwing a screw body 110 screwed into the screw hole 109.
03 is concentrically fixed to the cylindrical blade body 101.

[0006] In the drill 103, the line of intersection between a plurality of spiral grooves 108 provided on the outer peripheral surface of the shaft and one shaft end forms two straight blades 102, and the shaft center is the two straight blades 102. It is a chisel point that becomes a straight line over the blade. Drill 10
The other shaft end of 3 is inserted into the holding portion 105 of the cylindrical blade body 101 and is fixed concentrically, and the blade 102 protrudes outward in the axial direction from the blade 100 of the cylindrical blade body 101. ing.

In the above-described drilling tool, the mounting shaft portion 106 of the cylindrical blade body 101 is detachably mounted on a tool holding portion capable of rotating and descending a drilling machine. It rotates concentrically and integrally and descends.

When drilling a hole in a metal plate using this drilling tool, an operator preliminarily scribes a positioning mark at a predetermined drilling position, and cuts a dent for preventing displacement using a punch in the positioning mark. An operator operates a drilling machine, rotates the cylindrical blade body and the drill together by the tool holding unit, and lowers the chisel point of the drill 103 by the above-described scribing mark. A small centering hole in a state where the position of the drill 103 is prevented from being shifted, and the displacement of the cylindrical blade body 101 with respect to the drilling position is restrained. Blade 1 of body 101
00 comes into contact with the metal plate, and the blade 100 cuts through the metal plate to form a large-diameter hole that cannot be drilled by a drill alone.

The chips used for drilling the centering hole and the large-diameter hole grow into a relatively long length and have a spiral shape. Chips generated by the drill 103 spirally enter the cylindrical blade body 101 along the spiral groove while being wound around the spiral groove 108, and enter the chip discharge hole 107 through a gap between the coil springs 120, The chips are continuously discharged from the chip discharge holes 107 to the outside. Most of the chips generated by the cylindrical blade body 101 are wrapped around the outer periphery of the cylindrical blade body 101, and a part of the chips enters the cylindrical blade body 101. In addition, the cut disc between the drill 103 and the cylindrical blade body 101 falls naturally.

[0010]

However, when a hole is made in a synthetic resin plate using the above-described drilling tool, (1) Since the synthetic resin plate is fragile as compared with a metal plate, chips generated by the drill 103 cannot be removed. Instead of growing like a metal plate and becoming spirally long, it is folded at a relatively short length and wound around the spiral groove 108 of the drill 103. (2) The chips on the synthetic resin plate are melted by frictional heat with the blade 102 of the drill 103 and harden in a short time until drilling is completed. (3) At the point when the blade of the cylindrical blade body 101 has cut through the synthetic resin plate and drilled, the chips wound around the drill 103 and the cutting disk between the drill 103 and the cylindrical blade body 101 as described above are formed. Partially connected.

For this reason, the chips generated by the drill 103 and the cutting disk generated by the cylindrical blade body 101 adhere to the drill 103 after the drilling is completed without being pushed out by the coil spring 120. Therefore, when drilling is repeatedly performed while the chips and the cutting disk adhere to the drill 103, the chips and the cutting disk sequentially accumulate in the cylindrical blade body 101, and the cylindrical blade body 101 is clogged. In addition, it is difficult to remove the chips and the cutting disk from the drill 103 due to the hardening after melting, so that every time the drilling is completed, the operator manually works the chips and the cutting disk in the cylindrical blade body 101. Must be removed by drilling, which makes drilling work inefficient.

FIG. 8 is a schematic explanatory view showing a state in which a hole B is made in a synthetic resin plate A by using a drilling tool used for making a hole in a metal plate. As described above, the chips generated by the drill 103 are wound around the spiral groove 108 of the drill 103 and the drill 10 after the cutting disk C has been drilled.
3, the last part of the chips generated by the cylindrical blade body 101 remains on the lower edge of the hole B formed by the cylindrical blade body 101 and becomes a so-called burr D, and the burr D is drilled. Each time it is finished, it must be removed by the operator, and the efficiency of the drilling operation is further reduced.

When a hole B having a size that cannot be drilled by a drill alone is formed in the synthetic resin plate A using the above-described drilling tool used for drilling a metal plate as described above,
Each time the drilling is completed, the operator manually removes the chips and the cutting disk attached to the drill 103,
Since it is necessary for an operator to manually remove the burrs D on the lower edge of the hole B, for example, a cable insertion hole is provided in a synthetic resin housing in which the ignition control unit of the road lamp is housed. In such cases, the external dimensions of the object to be drilled, the positions of the holes, and the like are different, and the type of the object to be drilled is relatively large, but when the number of each specification is small, if the holes are formed by molding,
Since many types of molding dies are required, it is not possible to make holes at arbitrary positions, and the cost is higher than when drilling with a drilling machine. Therefore, at present, it is necessary to make a hole using the above-described drilling tool. Further, when the above-described drilling tool is used, since the above-mentioned manual work is forced, it is not possible to make a hole by continuous machining.

The present invention has been made in view of such circumstances, and has a cylindrical blade body having a blade at a cylindrical end, and a shaft which is provided concentrically within the cylindrical blade body and has a shaft end at a shaft end longer than the blade. And a piercing body having an apex that protrudes outward in the direction and can pierce the object to be pierced, so that chips are not generated by the piercing body for centering, and It is an object of the present invention to provide a drilling tool that can prevent chips and a cutting disk from adhering, can drill holes without burrs, and can automate drilling.

[0015] Further, by providing a structure in which a pushing body which can be relatively moved in the axial direction and is urged toward the blade by an urging means is provided in the cylindrical blade body, the hole is formed. It is an object of the present invention to provide a drilling tool that can surely push out a cutting disk to the outside of a cylindrical blade body when drilling is completed and that can efficiently automate drilling.

Further, the push body is provided with a through hole through which the piercing body is inserted and a tapered surface having a thin end on the blade side, so that chips generated by the cylindrical blade body are reduced. When the part enters the cylindrical blade body, the chips are accumulated in the space between the tapered surface and the cylindrical blade body, and when the drilling is completed, it can be reliably pushed out of the cylindrical blade body together with the cutting disk, An object of the present invention is to provide a drilling tool that can automate drilling more efficiently.

Further, by providing the piercing body with a stopper for restricting the movement of the pressing body by the urging means, the pointed portion can be reliably projected outward in the axial direction from the pressing body. It is an object of the present invention to provide a drilling tool that can perform the drilling.

[0018]

According to a first aspect of the present invention, there is provided a drilling tool comprising: a cylindrical blade body having a blade at a cylindrical end; and a coaxial core provided inside the cylindrical blade body; And a piercing body having an apex capable of protruding outward in the direction and piercing the object to be pierced.

According to the first aspect of the present invention, when a hole having a size that cannot be drilled by a drill alone is made in an object to be pierced, such as a synthetic resin plate, the piercing body and the cylindrical blade are integrally rotated and lowered. As a result, the tip of the piercing body pierces the center of the drilling position of the object to be pierced, and in this piercing state, the piercing body and the cylindrical blade body rotate and descend integrally. Only the piercing hole becomes larger, and no chips are generated by the apex. Therefore, chips are not wound around the piercing body, and the disk-shaped cutting disk between the piercing body and the cylindrical blade body can be prevented well from adhering to the piercing body. Drilling can be automated. Further, since the cut-out disk can be prevented from adhering to the piercing body, burrs can be less likely to be generated on the lower edge of the hole, and the work for removing burrs can be reduced. In order to pierce the point at the drilling position of the object to be drilled, it is possible to pierce the point at the center of the drilling position preset by the drilling automation device without providing a marking for positioning at the drilling position. It is possible to eliminate the scribing work and the work for preventing displacement due to the punch.

[0020] In the drilling tool according to the second aspect of the present invention, a pressing body which is relatively movable in an axial direction and is urged toward the blade by an urging means is provided in the cylindrical blade body. It is characterized by.

According to the second aspect of the present invention, when the drilling is completed by pressing the pressing body against the object to be drilled by the cylindrical blade body after the tip pierces the object to be drilled until the drilling is completed. At the same time, the disk-shaped cutting disk can be reliably pushed out of the cylindrical blade body, and the cutting disk can be reliably separated from the object to be drilled. For this reason, it is possible to satisfactorily prevent burrs from being generated at the lower edge of the hole, and to efficiently automate the drilling.

In the drilling tool according to a third aspect, the pressing body is
It is characterized in that a through hole through which the piercing body is inserted and a tapered surface having a thin end on the blade side are provided.

In the third aspect, most of the chips generated by the cylindrical blade are spirally discharged around the outer periphery of the cylindrical blade, and a part of the chips enter the cylindrical blade.
Since the pressing body provided inside the cylindrical blade has a tapered surface with a thin end on the blade side, some chips entering the cylindrical blade can be collected in the annular space between the tapered surface and the cylindrical blade. When the drilling is completed by the cylindrical blade body, the chips in the annular space can be reliably pushed out of the cylindrical blade body together with the cutting disk by the pressing body. Therefore, the accumulation of chips in the cylindrical blade body and the generation of burrs at the lower edge of the hole can be prevented well, and the drilling can be more efficiently automated.

Further, by providing a tapered surface with a thin end on the blade side, the contact area of the pressing body with the object to be pierced can be reduced as compared with the case where the tapered surface is not provided, and the peripheral surface has a lower peripheral speed. Can contact the object to be drilled,
The frictional resistance between the pressing body and the object to be pierced can be reduced, the calorific value of the portion where the cylindrical blade is pierced can be reduced, the melting of the chips generated by the cylindrical blade can be suppressed, and the melted chips can be suppressed. Can be satisfactorily prevented from entering the gap between the pressing body and the cylindrical blade body.

A piercing tool according to a fourth invention is characterized in that the piercing body is provided with a stopper for limiting the movement of the pressing body by the urging means.

According to the fourth aspect of the present invention, the tip can be reliably projected outward in the axial length direction from the pusher, and the tip is pierced into the center of the drilling position without being obstructed by the pusher. be able to.

[0027]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the drawings showing the embodiments. Embodiment 1 FIG. 1 is a longitudinal sectional front view of a drilling tool according to the present invention, and FIG. 2 is an exploded perspective view.

The drilling tool according to the present invention has a cylindrical blade body 1 having a blade 11 at one cylindrical end of a cylindrical part 10, and is provided concentrically within the cylindrical blade body 1, and has one end of a shaft part 20. A piercing body 2 having an apex 21 protruding outward in the axial direction from the blade 11 at the shaft end and capable of piercing the object A to be drilled, and a relative movement in the axial direction within the cylindrical blade body 1. The pusher 3 is provided so as to be capable of being provided, and an urging means 4 for urging the pusher 3 toward the blade 11.

The cylindrical blade body 1 has a plurality of blades 11 at one cylindrical end at appropriate intervals in the circumferential direction, and a bottom 12 at the other cylindrical end.
A cylindrical portion 10 having a bottom, a cylindrical holding portion 13 protruding outward from the center of the bottom 12 of the cylindrical portion 10, and a mounting shaft continuous to an edge of the holding portion 13. The mounting shaft 14 is detachably attached to a drilling machine or a tool holding portion of an automatic drilling device. Further, the holding portion 13 is provided with a screw hole 15 that opens to a hole at the center.

The piercing body 2 is concentric with the cylindrical blade body 1 by inserting the other shaft end of the shaft portion 20 into the holding portion 13 and tightening the screw body 5 screwed into the screw hole 15. Fixed to The point 21 is sharp and sharp enough to pierce a thermoplastic synthetic resin plate such as ABS resin. This point 21 is pointed, for example, in a substantially triangular pyramid shape,
The edge portion of the point 21 protrudes outward in the axial direction from the blade 11 of the cylindrical blade body 1. When the cylindrical blade body 1 and the piercing body 2 are integrally lowered, the amount of protrusion of the apex 21 from the blade 11 can be centered by piercing the synthetic resin plate before the blade 11 comes into contact with the synthetic resin plate. There is as a length. A circular stopper 22 having a diameter larger than that of the shaft portion 20 and restricting the movement of the pressing body 3 by the urging means 4 is protruded near the apex portion 21 of the shaft portion 20.

The pushing body 3 is provided at the center with the shaft 2 of the piercing body 2.
The cylindrical blade body 1 has a through hole 30 through which the “0” is inserted, and is formed in a cylindrical shape sized to have a slight gap between the outer peripheral surface and the inner peripheral surface of the cylindrical blade body 1. The pressing body 3 is provided with a tapered surface 31 having a thin end on the blade 11 side. The tapered surface 31 is provided, for example, from a position of 1/2 to 2/3 of the outer diameter dimension to a substantially central position in the axial direction. Annular concave portions 32 and 33 are provided at both end edges of the through hole 30 of the pressing body 3. The stopper 22 is inserted into one of the annular concave portions 32, and the annular concave portion 32 comes into contact with the stopper 22 to be urged. The movement of the pressing body by the means 4 is restricted.

The urging means 4 uses a coil spring 40, which is wound around the shaft portion 20 of the piercing body 2, one end of which is in contact with the annular concave portion 33, and the other end of which is the same as that of the cylindrical blade body 1. Bottom 12
, The pressing body 3 is urged against the stopper 22 by the elastic restoring force of the coil spring 40, and one end of the pressing body 3 is brought into contact with the stopper 22 by bringing the annular recess 32 into contact with the stopper 22. Rather, it protrudes outward in the axial direction.

In the drilling tool configured as described above, for example, the mounting shaft portion 14 of the cylindrical blade body 1 is inserted into a tool holding portion E capable of rotating and lowering a drilling machine or an automatic drilling device. It is detachably attached by tightening or the like. One nozzle (not shown) communicating with the pressurized air source is arranged at a position near the tool holding portion E toward the outer peripheral surface of the cylindrical portion 10 of the cylindrical blade body 1.

FIGS. 3, 4 and 5 are illustrations showing the process of drilling. When drilling a hole B in the drilling object A held on the table, the drilling tool is rotated and lowered by a drilling machine or a tool holder of an automatic drilling device.
Due to this lowering, the tip 21 of the piercing body 2 pierces the center of the drilling position of the object A to be drilled and is centered (# 1, FIG. 3).
FIG. 4a). The pierced portion is hollowed out by the rotation of the apex 21 and the pierced hole becomes larger, so that the amount of pierced portion increases and no chips are generated. That is, the piercing hole portion is melted by the frictional heat generated by the apex 21 and the piercing hole is enlarged, and only swelling chips are generated at the edge of the piercing hole, and no chips are generated.

In the process of increasing the amount of piercing of the tip 21, one end of the pressing body 3 comes into contact with the object A to be pierced (# 2 in FIG. 3,
4B), the pressing body 3 relatively moves against the elastic restoring force of the coil spring 40 (# 3 in FIG. 3), and after the movement stops,
The blade 11 of the cylindrical blade body 1 comes into contact with the drilled object A (# 4 in FIG. 3,
In FIG. 4C, the cylindrical blade body 1 pierces the object A to be pierced annularly to make the hole B described above (# 5 in FIG. 3).

Most of the chips generated when the cylindrical blade body 1 pierces the drilled object A are spirally discharged around the outer periphery of the cylindrical blade body 1 and wound around the outer peripheral surface of the cylindrical portion 10. That is, a part of the chips enters the cylindrical blade body 1. At this time, since the annular space 6 by the tapered surface 31 is provided between the pressing body 3 and the cylindrical blade body 1 in the cylindrical blade body 1,
Part of the chips entering the interior can be stored in the annular space 6. Further, since the tapered surface 31 is provided with a thin end on the blade side, the contact area of the pressing body 3 with the pierced material A can be reduced as compared with the case where the tapered surface is not provided, and the peripheral surface has a lower peripheral speed. Can be brought into contact with the object to be drilled A.
Therefore, the frictional resistance between the pressing body 3 and the object A to be pierced can be reduced, and the calorific value of the portion where the cylindrical blade body 1 pierces can be reduced.
Melting of the chips generated by the cylindrical blade body 1 can be suppressed, and the molten chips can be prevented from entering the gap between the pressing body 3 and the cylindrical blade body 1 satisfactorily. Chips can be properly prevented from entering the gap between the pressing body 3 and the cylindrical blade body 1, and chips in the annular space 6 can be easily dropped by the tapered surface 31.

Drilling is completed when the blade 11 of the cylindrical blade body 1 cuts through the drilled object A (# 6 in FIG. 3, d in FIG. 4).
At the same time, the pressing body 3 urged by the coil spring 40
3 reliably pushes the disk-shaped cutting disk C to the outside of the cylindrical blade body 1 (# 7 in FIG. 3, FIG. 5), and the chips in the annular space 6 are extruded by the extrusion of the cutting disk C. And the chips in the annular space 6 are easily dropped by the tapered surface 31. The chips in the annular space 6 are also discharged from the cylindrical blade body 1 and the lower edge of the hole B is removed. Burrs can be prevented from being generated. When drilling is completed by the cylindrical blade body 1, pressurized air is injected from the nozzle of the drilling machine or the automatic drilling device toward the outer peripheral surface of the cylindrical portion 10 of the cylindrical blade body 1, and The spiral swarf wrapped around is blown downward.

As described above, chips are not generated by the piercing body 2 for centering, and furthermore, generated by the cylindrical blade body 1,
A part of the chips that have entered the cylindrical blade body 1 is stored in the annular space 6 of the tapered surface 31, and the cutting disk C pierced by the cylindrical blade body 1 is pressed by the pressing body 3 into the axis of the cylindrical blade body 1. Since it can be extruded outward in the longitudinal direction and the chips in the annular space 6 can be discharged together with the extrusion,
It is possible to eliminate the accumulation of chips and cutting discs on the cylindrical blade body 1 and to automate drilling. Therefore,
For example, in the case where a hole for inserting a cable is provided in a synthetic resin housing in which an ignition control unit of a road light is accommodated, holes having the same size are formed on objects to be pierced, which have different external dimensions, hole positions, and the like. Is provided, continuous drilling can be performed by a drilling machine or an automatic drilling device, and the cost for providing holes can be reduced.

Further, since the piercing body 2 pierces the tip 21 of the pierced object A into the pierced object A, the piercing object 2 is not fixed to a table or the like, and even if the pierced object 2 is held by frictional resistance. The center of the drilling position can be accurately pierced, and drilling by the cylindrical blade body 1 can be performed accurately.
Therefore, it is possible to eliminate the scribing work for providing the positioning mark at the drilling position.

Second Embodiment FIG. 6 is a vertical sectional front view of a second embodiment. Embodiment 2
The drilling tool of the third embodiment does not have the pressing body 3 and the urging means 4 of the first embodiment, and the other configurations and operations are the same as those of the first embodiment. Description and structure are omitted.

Even in the second embodiment, the first embodiment
In the same manner as described above, no chips are generated by the piercing body 2, so that the chips can be prevented from winding around the piercing body 2, so that the cutting disk does not adhere to the piercing body 2 and is continuously formed by the automatic drilling device. Drilling can be performed, and the efficiency of the drilling operation can be improved.

In the case where the pressing body 3 is eliminated as in the second embodiment, a pressurized air jetting means communicating with a pressurized air source is provided in the cylindrical blade body 1, and the cylindrical blade body 1 is bored into the cylindrical blade body 1 by drilling. The entered chips and the cutting disk may be blown outward from the blade-side opening of the cylindrical blade body 1 by the compressed air injected by the compressed air injection means at the same time when the drilling is completed.

In Embodiments 1 and 2 described above, the tip 21 of the piercing body 2 has a structure that is pointed in a substantially triangular pyramid shape. Is also good. Further, the pointed portion 21 may be any pointed portion that can pierce the edge portion of the synthetic resin plate.

In the first and second embodiments described above, the pressing body 3 is cylindrical, but in addition, the pressing body 3 is offset from the center on one surface of a disk having a through hole through which the piercing body 2 is inserted. Alternatively, the structure having one or a plurality of protrusions capable of contacting the object to be pierced may be employed, and the structure of the pressing body 3 is not particularly limited. In the case of a cylindrical shape, a circumferential surface having a small diameter from the middle to one end in the axial direction may be used instead of the tapered surface.

In addition to the coil spring, the urging means 4 may use an elastic body such as a disc spring or a rubber ring. Alternatively, a gas chamber filled with gas may be provided in the cylindrical blade body 1. The pressing body 3 may be configured to be urged by the gas pressure in the gas chamber. In addition, the drilling tool according to the present invention can not only form a hole in a thermoplastic synthetic resin product, but also form a hole in a thermosetting synthetic resin product, for example.

[0046]

As described above in detail, according to the first aspect, when a predetermined hole is made in a material to be pierced such as a synthetic resin plate, a chip is not generated by a piercing member for centering and a cylindrical blade is used. Since the holes can be formed, the holes can be continuously drilled without performing the manual operation of removing the chips and the cutting disk from the piercing body, and the efficiency of the hole forming operation can be improved. In addition, since the cut-out disk can be prevented from adhering to the piercing body, burrs can be hardly generated on the lower edge of the hole, the deburring work can be reduced, and the drilling can be automated. Thus, the cost for providing the holes can be significantly reduced as compared with the case of using the existing drilling tool described above.

According to the second aspect of the present invention, the cut disc can be reliably pushed out of the cylindrical blade body at the same time when the drilling is completed, and the cut disc can be securely detached from the object to be drilled. In addition, it is possible to satisfactorily prevent the generation of burrs on the lower edge of the hole, efficiently automate the drilling, and further reduce the cost for providing the hole.

According to the third aspect of the invention, when a part of the chips generated by the cylinder blade enters the cylinder blade, the chips can be accumulated in the annular space between the tapered surface and the cylinder blade. Chips in the annular space can be reliably pushed out of the cylindrical blade body together with the cutting disk by the pressing body when drilling is completed by the cylindrical blade body. The generation of burrs on the side edges can be favorably prevented, the drilling can be more efficiently automated, and the cost for providing the holes can be further reduced.

Further, by providing a tapered surface with a thin end on the blade side, the contact area of the pressing body with the object to be pierced can be reduced as compared with the case where the tapered surface is not provided, and the peripheral surface has a lower peripheral speed. Can contact the object to be drilled,
The frictional resistance between the pressing body and the object to be pierced can be reduced, the calorific value of the portion where the cylindrical blade is pierced can be reduced, the melting of the chips generated by the cylindrical blade can be suppressed, and the melted chips can be suppressed. Can be satisfactorily prevented from entering the gap between the pressing body and the cylindrical blade body.

According to the fourth aspect of the invention, the tip can be made to protrude outward in the axial direction more than the pressing body, and the tip is pierced into the center of the drilling position without being obstructed by the pressing body. Can be.

[Brief description of the drawings]

FIG. 1 is a vertical sectional front view of a drilling tool according to a first embodiment of the present invention.

FIG. 2 is an exploded perspective view of the drilling tool according to the first embodiment of the present invention.

FIG. 3 is an explanatory diagram showing a drilling process in the drilling tool according to the first embodiment of the present invention.

FIG. 4 is an explanatory diagram showing a drilling process in the drilling tool according to the first embodiment of the present invention.

FIG. 5 is an explanatory diagram showing a drilling process in the drilling tool according to the first embodiment of the present invention.

FIG. 6 is a longitudinal sectional front view of a drilling tool according to a second embodiment of the present invention.

FIG. 7 is a sectional view showing a drilling tool used for drilling a metal plate.

FIG. 8 is a schematic explanatory view showing a state in which a hole is made in a synthetic resin plate using a drilling tool used for making a hole in a metal plate.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Cylindrical blade 11 Blade 2 Piercing body 21 Apex 3 Pressing body 31 Tapered surface 4 Urging means

Claims (4)

[Claims] 1. A cylindrical blade body having a blade at a cylindrical end, fixed to the cylindrical blade body so as to be integrally rotatable and integrally rotatable, and protruded from an axial end of the cylindrical end body outward in the axial length direction to be bored. And a piercing body having a pointed part capable of piercing an object. 2. The perforation according to claim 1, wherein a pressing body which is relatively movable in an axial direction and is urged toward the blade by an urging means is provided in the cylindrical blade body. tool. 3. The drilling tool according to claim 2, wherein the pressing body is provided with a through hole through which the piercing body is inserted, and a tapered surface having a thin end on the blade side. 4. The piercing body is provided with a stopper for restricting movement of the pressing body by a biasing means.
The drilling tool as described.