JP2922448B2 - Multi-stage bit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multi-stage bit for drilling a hole having an arbitrary diameter selected from a predetermined diameter in a steel plate or the like.

[0002]

2. Description of the Prior Art Conventionally, as shown in FIG. 7, a stepped conical body having a truncated outer shape of a base A is shown in FIG. And a small-diameter portion, a vertical groove 1 is formed, and an edge 2 on the rear side in the rotation direction of a groove 1a in which the vertical groove 1 of each step is formed.
There has been provided a multi-stage bit in which a blade portion B is formed which faces forward and downward in the rotational direction and protrudes radially outward and from the lower end of the step. This multi-stage bit is used when drilling a steel plate or the like having a thickness within one height. With this single bit, from the minimum diameter stage 2a to the maximum diameter stage 2x,
It has a feature in that a hole having a diameter corresponding to the step can be formed using an arbitrary step.

In the case of this multi-stage bit, the shank portion 3 to be attached to the drilling device side (drilling machine, portable electric drill), the base A, and the tip drill 4 having the smallest diameter at the tip are integrally formed. I was

In actual drilling, for example,
When drilling using the fourth step from the tip, after attaching the shank part 3 to the drill device,
Drilling is performed with a tip drill, then at the second step, then at the third step, and then at the desired fourth step. Installation work is performed.

[0005] For this reason, the frequency of use of the tip drill and the cutting edge of the step on the tip side is higher, and accordingly, the wear and damage are greater on the tip drill and the cutting edge of the step on the tip side.

As a result, although the blade portion of the step near the shank is hardly worn, the blade of the step on the tip side is worn or damaged. He had a situation that he had to do.

In particular, if the tip drill is damaged immediately after starting the drilling operation using a new multi-stage bit, the multi-stage bit is discarded without using the blade at the subsequent step. Even irrational things will happen. And, as described above, in fact, the breakage often occurs on the tip end side with a small diameter, which has been a serious problem in production efficiency.

The present invention has been made in view of the above situation, and has as its object to provide a partially replaceable multi-stage bit.

[0009]

In order to solve the above-mentioned problems, a multi-stage bit according to the first aspect of the present invention is a stepped conical body whose base has a truncated outer shape. A longitudinal groove is formed from the large diameter portion to the small diameter portion of the conical body, and the groove on which the vertical groove of each step is formed is formed on the edge on the rotation rear side in the rotation direction, forward and downward in the rotation direction and radial direction. This is a multi-stage bit in which a blade portion protruding outward and from the lower end of the step portion is formed, and by drilling with a blade portion of an arbitrary selected step portion, it is possible to drill a hole having a diameter corresponding to the step portion. In order for the multi-stage bit to drill a hole with a minimum diameter at the front end of the base, a blade having the same diameter or a small diameter as the blade formed at the foremost step of the base is provided at the tip. The tip drill, which is arranged to face, is detachably attached to the base. It is characterized in.

In the multi-stage bit configured as described above, even if the most frequently used and most likely to be damaged tip drill is broken, only the tip drill can be replaced with a new one. Because it can, expensive bases are not disposed of for that purpose.

[0011]

In one embodiment of the multi-stage bit according to the first aspect of the present invention, the vertical groove is formed in a spiral shape (rotating) on the outer periphery of the stepped cone in a direction opposite to the rotating direction. (Refers to a spiral shape that rotates from the tip side in the opposite direction to the shank portion and advances toward the shank portion side), and smoothly discharges the cuttings cut by the blade portion upward. It becomes possible.

The blade has a rake angle equal to the spiral inclination angle of the vertical groove, and the front surface of the blade substantially coincides with the edge of the vertical groove on the rear side in the rotation direction. Thus, the chips can be more smoothly discharged without being disturbed by the blade portion located above.

In one embodiment of the multi-stage bit, it is desirable that each blade portion of the base is formed by burying a carbide tip in a rear edge of the longitudinal groove. In this case, The base except the blade can be made of ordinary inexpensive steel material, and only the tip of the blade needs to be welded with a chip such as a cemented carbide with excellent machinability and durability, which can be manufactured at low cost and increase productivity. In addition, the multi-stage bit can maintain good machinability over a long period of time and is a multi-stage bit excellent in durability.

Further, as one embodiment, if the shank portion for attaching the base portion to the drill device side is detachably mounted on the base portion, the base portion that is worn will be described. And the shank part with little wear becomes a reasonable multi-stage bit that can be used semi-permanently.

Further, as one embodiment, a through hole is formed at the center of the base, and from the tip of the through hole,
If the center drill whose base end is attached to the tip of the shank portion is arranged so as to protrude, positioning becomes easy in drilling work, and the first through-hole is formed in a short time. Therefore, when drilling a desired diameter, the entire drilling time can be shortened.

In one embodiment, when a center drill sleeve is interposed between the shank portion and the center drill, a commercially available drill can be used as the center drill. If the diameter of the center drill sleeve is configured to be large, even if a buckling load is applied to the tip of the center drill, buckling resistance is improved and breakage of the center drill is reduced as much as possible. Becomes possible.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a multistage bit according to the present invention will be specifically described below with reference to the drawings.

FIG. 1 is an exploded view showing the configuration of a multi-stage bit according to the present invention. FIG. 1 (a) is a side view of a disassembled state showing a shank portion, a center drill sleeve attached to a tip end thereof, and a tip drill. FIG. 2B is a side view of the disassembled state showing the base of the multi-stage bit whose base end is attached to the shank portion of FIG.
1 is an overall side view in which the left half of the multi-stage bit shown in FIG. 1 is assembled into one, and FIG. 2 (b) is a fifth stage of the multi-stage bit shown in FIG. FIG. 3C is an overall side view in a state, and FIG. 4C is a cross-sectional view taken along line II of FIG.

In these figures, A is a base having a truncated conical body as a whole, 1 is a vertical groove formed in the vertical direction (axial direction) over the entire length of the base A, and 2 is a minimum groove. Steps formed stepwise on the outer periphery of the base from the step 2a to the step 2x having the largest diameter, B is a blade formed on the base A, 3
Is a shank portion, 4 is a tip drill, 6 is a center drill sleeve, and 9 is a center drill.

As shown in FIG. 1B, a vertical groove 1 is formed in a base A of the multi-stage bit, and each of the steps 2a to 2x is formed.
The edge 1b of the groove 1a in which the vertical groove 1 is formed on the rear side in the rotational direction is provided with a cemented carbide tip (hereinafter, referred to as a “hard”) that forms the blade portion B.
Are simply welded ("brazed" in this embodiment). The tip faces forward and downward in the rotational direction and protrudes radially outward and from the lower end of the step. In other words, the tip forms a rake angle of the blade portion B in which the front face in the radial direction is inclined in the matching direction, and the front face of the tip is inclined rearward in the rotation direction at approximately 25 degrees at the upper end with respect to the rotation direction,
The outer surface of the chip protrudes radially outward from the outer peripheral surface of the base A, and the lower end of the chip is stepped (2a).
~ 2x) protrudes downward from the lower surface. A concave portion 1c communicating with the groove 1a is formed on the front side in the rotation direction of the chip, and is arranged such that substantially the entire front surface of the chip projects radially outward from the groove 1a and the outer peripheral surface. , Workpiece (steel plate, etc.) at the front and bottom of the insert
Can be cut.

As shown in FIG. 2A, a through hole 5 is formed over the entire length at the center of the shaft of the base A, and an upper portion 5a of the through hole 5 The central portion 5b underneath has a large diameter so that the distal end can be removably inserted. The base end has a bottomed hole 3B of the shank portion 3.
The base end portion 6a of the center drill sleeve 6, which is detachably inserted into the inside, is configured to be housed. A female screw 5A is screwed into a distal end portion 5c of the through hole 5, and a core drill type distal drill 4 having a screw 4A at a base end is detachable.

By the way, as shown in FIG.
The upper portion 5a of the through hole 5 into which the shank portion 3 is inserted is provided with a protrusion 5d protruding toward the inner diameter side.
As shown in FIG. 1A, an inverted L-shaped engaging groove 3A through which the protrusion 5d can pass is provided at the tip of the shank portion 3.
1 (only one of them is shown in FIG. 1 (a)), and the protrusion 5 d is provided at the bottom of the L-shaped bent portion of one of the engagement grooves 3 </ b> A at the L-shaped back. A locking ball 7 for locking in a locked state at the portion is disposed so as to be able to retreat until it becomes substantially flat toward the groove bottom. That is, the base A is engaged with the shank portion 3 when the protrusion 5d on the base A side passes over the locking ball 7, and the engagement is released by moving in the opposite direction, and the shank portion 3 can be moved to the L-shaped opening side. Is configured.

As shown in FIG. 2 (a), the center drill sleeve 6 is fixed to the bottomed hole 3B of the shank portion 3 by a diameter provided substantially at the center of the shank portion 3 in the vertical direction. The center drill sleeve 6 is pressed and locked to the shank portion 3 on the bottom surface of the bolt 8 by screwing a bolt (hexagon socket head bolt) 8 into the mounting bolt hole 3e in the direction into the fixing recess 6a of the center drill sleeve 6. Done by Accordingly, by loosening the bolt 8 with a tool (a hexagon wrench in the case of a hexagon socket head bolt), the center drill sleeve 6 can be attached and detached in the axial direction.

As shown in FIGS. 1 and 2, the center drill sleeve 6 is provided with a bottomed hole 6B which is opened on the tip side at the axis thereof. Is fixed. The center drill 9 is fixed by screwing a bolt (for example, a hexagon socket head bolt) 10 into a radial mounting bolt hole 6 e provided at the tip of the center drill sleeve 6 into a fixing recess 9 a of the center drill 9. This is performed by pressing and locking the center drill 9 to the center drill sleeve 6 on the bottom surface of the bolt 10. Therefore, the center drill 9 can be attached and detached in the axial direction by loosening the bolt 10 with a tool (hexagon wrench in the case of a hexagon socket head bolt).

As shown in FIG. 2 (b), in the multi-stage bit, when drilling, a desired step is specified, and when the step is completed, further drilling is prevented. In order to achieve this, a stopper S whose lower end is located approximately at the lower end of the upper step (more precisely, the lower end is located slightly lower than the lower end of the upper step) can be detachably attached. Have been. This stopper S is shown in FIG.
As shown in (c), one end 18 of the cut portion of the substantially ring-shaped band material cut at a part of the ring is bent inward, so that the base portion A is vertically extended. It is configured to be locked in the formed locking groove 19, and the height H
Is equal to the height of each step 2, and is slightly higher than the height of the step. In this embodiment, the locking groove 19 is provided separately from the vertical groove 1 for locking the end 18 of the stopper S, but the vertical groove 1 may be used.

In the case of the stopper S according to this embodiment, it is necessary to prepare a ring having a different ring diameter in accordance with the circumference of each step.

Another embodiment of the stopper is shown in FIG.
As shown in the figure, a locking hole 12 extending in the radial direction for locking the stopper S is formed in the vertical position of each stepped portion 2 of the base A, and the stopper S can be pulled by a spring 13 on the side thereof. The locking pin 14 disposed in the locking hole 12 may be inserted into the locking hole 12 and locked. In this case, the stopper S itself is, as shown in FIG.
It may be rectangular in plan view with a step in the thickness direction. Therefore, it is necessary to prepare stoppers S having different ring diameters according to the peripheral length of each step portion, such as the stopper of the embodiment shown in FIG. There is no.

As another embodiment related to the stopper, as shown in FIG.
Together constitute at which the formation of the projections 15 on the inner pitch P equal to the pitch P _A of the step portion 2 in the radial direction of the opposed two positions to the base A of the peripheral surface _B of the flange portion 16 of the upper end of the base A, A recess 16a in which a locking ball 16b is buried in the center so as to be retractable in the inner diameter direction to accommodate the projection 15 is formed at two locations facing each other in the radial direction. The stopper ball 16b is retracted into the center of the concave portion 16a, and the stopper ball S is fitted to the base A by rotating the stopper S in any circumferential direction. You may comprise so that it can be set. Also in the case of the stopper according to this embodiment, there is no need to prepare a plurality of stoppers corresponding to the circumference of each step portion as in the embodiment shown in FIG.
It is excellent in that it is only necessary to prepare one cylindrical shape.

The multi-stage bit constructed as described above can perform a drilling operation as described below at the time of drilling work, and each part can be replaced.

Assuming now that the steel plate is to be drilled using the step portion 2 at the fourth step from the tip, first, the lower end at the fifth step from the tip (exactly a position slightly lower than the lower end at the fifth step; After setting the lower end of the stopper S at 2 (b), the center drill 9 is used to drill a hole for positioning the center. Subsequently, the tip drill 4 drills a small-diameter hole. Is established. And the first
Drilling of the hole diameter corresponding to the diameter of each of the steps from the third step to the third step is performed, and finally, the hole diameter corresponding to the diameter of the fourth step which is the target hole diameter is performed. It is. At the time of drilling a hole having a diameter corresponding to the diameter of the fourth step, when the lower end of the stopper S comes into contact with the upper surface of the steel plate, the drilling operation is stopped. Drilling can be performed with the stepped portion.

At the time of the drilling, the cuttings drilled at each step are discharged to the upper part through the longitudinal groove 1 to maintain a smooth drilling operation.

In the above-mentioned drilling, the center drill 9 and the tip drill 4 which are always used are the most severely worn and damaged, but in the multi-stage bit according to the present invention, the center drill 9 and the tip drill 4 are bolted. Can be easily removed and attached by loosening with a hexagon wrench, so that it can be easily replaced. In particular, since the center drill 9 having a high possibility of breakage is replaceable, even if the center drill 9 breaks, there is no waste of discarding the entire multi-stage bit.

Even if the base A is worn, for example, if the center drill 9 and the tip drill 4 do not need to be replaced after replacement, only the base A alone is replaced, and the shank 3 and the center drill 4 are replaced. 9 and the tip drill 4 can be used as they are, and by always performing the minimum replacement, the multi-stage bit can always be used in the best condition. In addition, since the replacement of the base portion A is performed only by locking the protrusion 5d on the base portion A side by the locking ball 7, the base portion A can be easily detached and attached only by hand without using a tool.

As is conventional, according to this multi-stage bit,
Despite the useable portion remaining, it is no longer possible to perform an unreasonable operation such as replacing the entire multi-stage bit due to a portion being damaged or worn.

In the above embodiment, the core drill and the center drill are attached at the tip of the base. However, a drill having the same form as the center drill having a large diameter equal to the outer diameter of the tip drill is attached. The configuration may be as follows.

By the way, in the configuration of the multi-stage bit shown in FIGS. 1 and 2 above, the chips cut by the blade portion B are basically discharged upward along the vertical groove 1 as described above. As shown in FIG. 5 and FIG. 6, the vertical groove is formed by a spiral vertical groove 1 which is raised in the opposite direction to the rotation direction of the multi-stage bit and has an angle equal to the rake angle of the front surface of the blade portion B. With this configuration, the cutting chips cut on the front surface of the blade portion B of each step portion 2 are smoothly discharged upward without being disturbed by the blade portion B located above, so that the cutting property is further improved. This figure 5,
The multi-stage bit shown in FIG. 6 has basically the same configuration as the multi-stage bit shown in FIGS. 1 and 2 except for the configuration of the vertical groove 1.

That is, in FIGS. 5 and 6, 3 is a shank portion, 4 is a tip drill, 6 is a center drill sleeve,
Reference numeral 9 denotes a center drill, which is connected to the base A by a configuration similar to that of the above-described embodiment (see FIG. 2A). In the multi-stage bit according to this embodiment, the vertical groove 1 is spirally formed on the outer periphery of the base A in the shape of a truncated cone and extends in the axial direction (longitudinal direction) as described above. The cemented carbide tip) is disposed on the edge 1 b on the rear side in the rotation direction of the vertical groove 1 so as to have a rake angle equal to the spiral inclination (winding angle) of the vertical groove 1. Therefore, in the multi-stage bit shown in FIGS. 5 and 6, in the multi-stage bit shown in FIGS. 1 and 2, the recessed portion 1c (the groove 1a in FIG. There is no recess 1c). In FIGS. 5 and 6,
Reference numeral 19 denotes a vertical locking groove for locking the stopper S, and a stopper S having the same configuration as that shown in FIG.

The multi-stage bit according to this embodiment also has basically the same excellent operational effects as the above-described multi-stage bit, except that the cutting chips cut by the blade portion B are more smoothly discharged.

[0039]

According to the multi-stage bit according to the present invention, a worn or damaged center drill,
Since only the tip drill or the base needs to be replaced, it is possible to use it economically and without waste.

Further, replacement of each part can be easily performed.

[Brief description of the drawings]

FIG. 1 is an exploded view showing a configuration of a multi-stage bit according to the present invention, in which (a) is an exploded view showing a shank portion, a center drill sleeve and a tip drill attached to a tip thereof, and (b) is a multi-stage bit. FIG. 3 is an exploded view showing a base portion and a tip drill at the tip thereof.

2A is an overall side view of the left half of the multi-stage bit shown in FIG. 1 in an assembled state, and FIG.
5A is an overall side view of the multi-stage bit shown in FIG. 5A with a stopper attached to the fifth stage, and FIG. 7C is a cross-sectional view taken along the line II of FIG. .

FIG. 3 is a view showing a stopper different from that of FIG. 2 (b), showing a state in which the stopper is attached to a multi-stage bit, (a) being a partially sectional side view, and (b) being a right side. (A) II with the stopper and lock pin omitted
FIG. 2 is a sectional view taken in the direction of the arrow II.

FIGS. 4A and 4B are views showing a stopper having a different configuration from FIGS. 2B and 3; FIG. 4A is a side view showing a cross section of the stopper, and FIG. 4B is a cross-sectional view taken along the line III-III of FIG. is there.

FIG. 5 is an exploded view showing a configuration of a multi-stage bit according to another embodiment of the present invention.

6 is an overall side view in a state where a stopper is attached to a fourth stage in a state where the components of the multi-stage bit shown in FIG. 5 are assembled.

FIG. 7 is an overall perspective view showing the configuration of a conventional multi-stage bit.

[Explanation of symbols]

 A: Base B: Blade 1: Vertical groove 1a: Groove 2: Step 3: Shank 4: Tip drill

Claims (7)

(57) [Claims] An outer shape of a base portion is a stepped conical body having a truncated truncated cone. Vertical grooves are formed from a large diameter portion to a small diameter portion of the stepped conical body, and vertical grooves of each step portion are formed. A blade portion is formed at the edge on the rear side in the rotation direction of the groove portion facing forward and downward in the rotation direction and protrudes radially outward and from the lower end of the step portion. A multi-stage bit that allows the drilling of a hole diameter corresponding to the step portion, whereby the multi-stage bit is formed at the leading end of the base in order to drill a hole with a minimum diameter on the front side of the base. A blade having the same diameter or a small diameter as the blade formed at the step portion is disposed toward the distal end, and a distal end drill is disposed so as to be detachable from the base. Multi-stage bit. 2. The flute according to claim 1, wherein the flute is formed on the outer periphery of the stepped cone by a spiral groove which rises in a direction opposite to the rotation direction and becomes freely accessible. Multi-stage bit. 3. The blade section has a rake angle equal to the spiral inclination angle of the vertical groove, and the front surface of the blade section is configured to substantially coincide with the edge of the vertical groove on the rear side in the rotation direction. 3. The multi-stage bit according to claim 2, wherein: 4. The multi-stage bit according to claim 1, wherein each blade portion of the base is formed by embedding a carbide tip in a rear edge of the vertical groove. 5. The base according to claim 1, wherein a shank portion for attaching the base to a drill device side is detachably attached to the base. The multi-stage bit described in the paragraph. 6. A through hole is formed in a center of the base,
The multi-stage bit according to claim 4, wherein a center drill having a base end attached to a tip end of the shank portion protrudes from a tip end of the through hole. 7. The multi-stage bit according to claim 5, wherein a center drill sleeve is interposed between the shank portion and the center drill.