JPH052295Y2 - - Google Patents

Description

[Detailed description of the invention] [Field of industrial application] This invention is a drill shaft that is installed at the tip of a drill shaft for drilling small holes in concrete structures such as building walls and ceilings. The present invention relates to a cutting member made of powdered sintered metal.

[Conventional technology]

When installing decorative boards on the walls or ceilings of concrete structures, it is well known that many small holes are drilled in the walls or ceilings, and anchors are driven into these small holes to support the decorative boards. It's summery.

Conventionally, a so-called twist drill was attached to an electric drill machine, etc., and axial forward/backward vibration and rotational motion were applied to the twist drill to perform drilling by axial impact fracture and rotary cutting. This type of twist drill generates vibration and noise due to impact breakage, and it has been pointed out that the tip is difficult to bite into when starting drilling.

Therefore, a drill as shown in Utility Model Application No. 60-87650 was developed. This consists of a cylindrical cutting member provided at the tip of the shank shaft, and a slit parallel to the shaft provided in this cutting member, making it possible to drill holes only by rotation without applying any impact in the axial direction.

Also, as shown in Japanese Patent Application Laid-open No. 146412/1983,
A drill has also been developed in which the tip of the cutting member is concave and an edge is formed on the periphery to increase the biting force.

In any of the above cases, JP-A-61-
As shown in Figure 3 of the drawing of No. 146412, the proximal end surface of the cutting member and the distal end surface of the shank shaft were brazed in a parallel end face butt joint state.

[Problem that the invention attempts to solve]

According to the end face butt joint structure described above, it is very difficult to center and braze the cutting member with respect to the shank shaft. If the cutting member is even slightly eccentric in the radial direction of the shank shaft, it will be difficult to center the initial bite and the desired drilling will not be obtained, so strict tolerances have been required. In this case,
When the cutting section is divided into parts as shown in FIG. 4 of the above-mentioned Japanese Utility Model Application No. 60-87650, it is necessary to center each divided cutting part individually, which is extremely difficult. In reality, the cutting member had to be picked up with tweezers and soldered, and according to experiments, only one out of 100 produced was able to be centered.

Even if the soldering is done within tolerances, even a slight deviation will be greatly amplified during high-speed rotation. With conventional twist drills, holes were drilled at medium speeds of approximately 1,000 rpm or less, so this problem did not occur.
When used at high speed rotation of 27,000 rpm, the cutting member, which is the free end at the tip of the shaft, shakes, causing eccentric rotation, so even the slightest misalignment is greatly amplified. It became a problem.

In addition, in order to make both end faces closely adhere in the radial direction, flatness on the order of microns is required, and even if flatness is achieved, axial deviation may occur due to the thickness of the brazing material in the radial direction when joining. was inevitable. Furthermore, it was found that the bonding area of only the end face was small and the bonding area was easily separated from the axial direction.

Further, in this type of rotary drill, there is a problem that if the chip discharge performance is poor, frictional heat increases and the cutting ability decreases, but the drill was insufficient in any of the above cases.

Therefore, the present invention was devised in view of the above circumstances, and uses taper engagement to perform accurate brazing centering, and firmly joins a wide area by tapered contact in a wedge engagement state. make it possible,
Another object of the present invention is to provide a cutting member for a drill that can effectively discharge chips.

[Means for solving problems]

To achieve the above object, the cutting member of the rotary drill for concrete drilling according to the present invention has a large diameter and is attached to the tip of a shank shaft having a through hole in the axial direction, and contains diamond, etc. A cylindrical upper half made of powdered sintered metal with a diametrical slit extending axially from the tip surface and a tapered shaft that engages with the tip of the shank shaft for centering in the axial direction. A hole is formed in the center of the lower half to communicate the slit and the through hole with a smaller diameter than the through hole, and on both sides of the outer peripheral surface of the lower half is formed a hole that communicates the slit with the through hole. A groove is formed on the same surface as the outer peripheral surface of the shank shaft and communicates with the slit.

[Effect of invention]

Centering is performed by taperingly engaging the cutting member with the tip of the shank shaft, and the tapered engaging surface is integrated by brazing or the like.

Further, the chips flow smoothly in the axial direction on the outer surface of the shank shaft through the slits and grooves, thereby reducing the accumulation of chips.

[Example of idea]

The drawings show an embodiment of the cutting member of the rotary drill for drilling concrete according to the present invention, in which FIG. 1 is a perspective view of the entire structure, FIG. 2 is a sectional view of the same, FIG. The figure is a sectional view illustrating the mounting hole state.

1 is a drill, 2 is a metal round bar-shaped shank shaft, 3 is a cutting member made of powdered sintered metal containing diamond or the like at the tip of the shank shaft 2, 4
5 is a mounting portion configured on the base end side of the shank shaft 2;
is a through hole extending from the base end to the tip end at the center of the shaft.

Thus, the cutting member 3 has a large-diameter outer shape from the cylindrical upper half 6 and the tapered lower half 7 that constitutes the engagement protrusion, which is the engagement surface. 6
A slit 8 extending diametrically from a has a bifurcated shape in the axial direction, and grooves 9 are provided on the outer circumferential surface communicating with the slit 8. The groove 9 is formed on substantially the same surface as the outer peripheral surface of the shank shaft 2 so that chips can be easily discharged. 10 in the figure is the slit 8 mentioned above.
A cutting edge 11 on the outer surface that intersects with is a hole that is provided at the center of the cutting member and constitutes a part of the through hole 5, and has a smaller diameter than the through hole 5 and exhibits an orifice effect.

Further, an engagement hole portion 13, which is an engagement surface, is provided on the distal end surface 12 of the shank shaft 2 so as to be inclined inward.

Further, the mounting portion 4 of the shank shaft 2 is arranged from the shank shaft proximal intermediate 14 to the proximal end 15, which has a large diameter.
Tapered portion 16 and tapered portion 16 that taper toward
and a male threaded portion 17 located further toward the proximal end. In this case, the shank shaft 2 is formed by swaging a rod-shaped hollow tube of carbon steel pipe STKM13 to STKM19 by cold forging, and the taper angle of the mounting portion 4 is 1 to 8 degrees, preferably 1 to 4 degrees. Form within the specified range.

In the figure, 18 is a concrete drilling machine, 19 is a tapered mounting hole, 20 is a female thread, 21 is a communicating hole, 22 is an intervening member inserted into the tip of the through hole 5,
23 is the hole.

When attaching the cutting member 3 to the shank shaft 2, the tapered lower half 7 is engaged with the engagement hole 13 and integrated by brazing or the like with a large engagement area. At that time, if a guide pin (not shown) is inserted into the hole 11 of the cutting member 3 and the tip of the guide pin is made to protrude, the tip of the guide pin will fit into the through hole 5 of the shank shaft 2 and be positioned. Centering can be performed accurately and easily.

When using the concrete structure drilling machine 1
Tapered part 1 on the base end side of the shank shaft in the mounting hole 19 of 8.
6 and attach the drill 1. Male thread part 17
Since it has approximately the same diameter as the tapered portion 16 or has a reduced diameter, it can be smoothly engaged along the taper of the mounting hole 17, and then the male threaded portion 17 is screwed into the female threaded portion 20 to complete the installation.

When the drill 1 is rotated, the tapered portion 16 acts as a wedge to engage the mounting hole 19. When drilling a hole C1 in concrete C as shown in FIG. At the same time, the medium and chips are discharged from the outer periphery of the shank shaft 2 through the slit 8 and the grooves 9, 9. In this case, by the hole 11,
The amount of medium injected can be made constant regardless of the size of the shank shaft diameter, and if the medium is air or the like, the cooling effect on the cutting member 3 can be further exerted. Furthermore, the presence of the hole 23 in the intervening member 22 also makes it possible to keep the amount of medium injected constant.

According to the above embodiment, the following effects are achieved.

(a) For structural concrete drilling drills in which a large-diameter cylindrical cutting member is brazed to the tip of the shank shaft, there is
No. 3 did not take into consideration the discharge of chips, but by discharging chips from the grooves 9, 9, the cutting force could be increased dramatically. In particular, an efficient mechanism was achieved in which the grooves 9, 9 are communicated with each other through the slit 8 provided in the diametrical direction.

(b) The shank shaft 2, the through hole 5, and the mounting portion 4 can be manufactured by swaging processing,
Due to the compressive force applied to the circumferential surface during processing, the direction of the metal fibers was aligned in the axial direction. With conventional shank shafts that are made by drilling holes in rod material or threading into pipes, one of the causes is that the metal fibers are not aligned, which causes blurring during high-speed rotation cutting, making it difficult to drill accurately. Not only was this not possible, but the shank shaft was also bent and damaged, but this can be resolved.

The cutting member 3 is not limited to the one embodiment described above, and the structure of the cutting blade, the type of cemented carbide powder sintered metal, etc. can be selected from various types. As shown in FIG. 5, an engagement hole 25 is formed as an engagement surface in the lower half of the cutting member 3, and the tip of the shank shaft 2 is connected to the engagement protrusion 2.
An engagement structure replacing the number 4 is also possible. In this case, the core portion 26 that enters the through hole 5 may be made to protrude.

[Effect of idea]

As explained above, the cutting member of the rotary drill for concrete drilling according to the present invention provides the following effects.

By centering and engaging the base of the cutting member with the tip of the shank shaft, it was possible to integrate the cutting member with brazing in a simple and accurately centered state.

This eliminates the problems that conventional end face brazing was weak and that it was difficult to achieve perfect alignment over the ring shape of each end face between the cutting member and the shank shaft, and the joint area was increased to create a wedge engagement between the joint surfaces. This allows for strong integration. In particular, with conventional end face brazing, stress concentration occurs due to high speed rotation and peeling progresses quickly, but this problem has been resolved and it has become possible to drill a large number of holes.

In addition to forming a slit extending in the diametrical direction, grooves that are approximately flush with the outer peripheral surface of the shank shaft are formed on both sides of the lower half and communicated with the slit, thereby improving chip discharge performance. We were able to improve our cutting ability.

[Brief explanation of the drawing]

The drawings show an embodiment of the cutting member of the rotary drill for drilling concrete according to the present invention, in which FIG. 1 is a perspective view of the entire structure, FIG. 2 is a sectional view of the same, FIG. The figure is a cross-sectional view explaining the state of mounting holes, and FIG. 5 is a cross-sectional view of a main part showing another example. DESCRIPTION OF SYMBOLS 1...Drill, 2...Shank shaft, 3...Cutting member, 4...Mounting part, 5...Through hole, 6...Upper half, 7...Lower half, 8...Slit, 9... …groove,
10... Cutting blade, 11... Hole, 13, 25... Engagement hole portion, 14... Shank shaft proximal end intermediate, 16...
Tapered portion, 17... Male threaded portion, 24... Engaging protrusion.

Claims (1)

[Scope of utility model registration request] It is a large-diameter cutting member that is attached to the tip of a shank shaft that has a through hole in the axial direction, and is made of powdered sintered metal containing diamond, etc., and has a diametrically extending slit extending from the tip surface in the axial direction. It consists of a cylindrical upper half and a lower half formed with a tapered engagement surface that engages with the tip of the shank shaft so that it can be centered in the axial direction. A hole with a smaller diameter than the through hole is formed in the center and communicates between the slit and the through hole, and on both sides of the outer circumferential surface of the lower half, a groove is formed on the same plane as the outer circumferential surface of the shank shaft and communicates with the slit. A cutting member for a rotary drill for concrete drilling that is equipped with a