JPH0413128Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a diamond core drill for drilling holes in hard and brittle materials, particularly plate glass.

[Prior Art] It is well known that diamond core drills are excellent in both machining efficiency and machining accuracy when drilling holes in hard and brittle materials such as glass. As shown in Fig. 5, it has a structure in which a diamond grinding wheel part 2 is provided at the tip of a hollow shank 1, and by grinding and removing the workpiece with the annular grinding wheel tip 3, a hole is drilled and a core is formed at the same time. It is called a core drill because it separates the The machining fluid can be jetted out through the hollow part 4 and effectively supplied to the grinding part.

Although a diamond core drill is a high-performance tool, it has the disadvantage that it tends to chip at the edges of holes drilled in plate glass, etc. Not only do chips impair the aesthetics, but they can also lead to cracks and lead to the destruction of the product with the hole.

Chips occur on the exit side of the tool during penetration, so
One way to prevent chipping is to process the glass from both sides. Dig from one side to the middle of the plate thickness and stop, then dig from the other side and penetrate at the center of the plate thickness.

The only way to make a chip-free hole was to process from both sides as described above, but it required two spindles facing each other while maintaining concentricity, and the machine and operation were complicated. The concentricity of both spindles is not necessarily accurate, and there is also the drawback that the holes are misaligned at the through-hole. In addition, cracks may occur at the penetration portion. To prevent this, there is a method of using drills with slightly different diameters for machining from both sides, but in this case, the hole will have a step difference.

[Problem to be solved by the invention] The problem of the invention is to solve the problem from one side using a single-axis machine.
To provide a diamond core drill capable of drilling a chip-free hole in plate glass or the like in just one operation.

[Means for Solving the Problems] The means of the present invention consists of a cylindrical part with a nominal diameter, and an inclined part connected to the tip of the cylindrical part, the diameter of which gradually decreases and ends in a drill tip with a diameter smaller than the nominal diameter, In addition, a diamond grinding wheel portion is provided at the tip of the steel shank, which has a horizontal hole that communicates with the through hole formed in the drill shaft core and opens in the inclined portion.

[Operation] The core drill of the present invention shown in Fig. 1 is pushed into a plate glass while rotating at high speed, and the leading edge 16 reaches the back of the plate and a hole is penetrated with an opening smaller than the nominal diameter, and when pushed further, The conical part 13 grinds and enlarges the inner wall of the hole, and finally the cylindrical part 12 completes a straight hole of the nominal diameter. When penetrating with the tool tip 16, chips occur at the edge of the opening as described above, but in the enlarging process thereafter, the chipped portions are ground away, creating an opening with no chips at all.

The machining fluid ejected from the lower end through the through hole 18 flows to the upper part through the gap between the inner wall of the hole and the tool, which has already been formed, before penetrating, and acts to cool, reduce friction, carry out chips, etc. . After the tip 16 penetrates, the machining liquid from the tip opening wastefully squirts into the space below and does not reach the conical liquid 13 which performs the important grinding action. In this process, the machining fluid flows through the side hole 19, which serves as a side channel.
The centrifugal force generated by the rotation of the diamond core drill effectively supplies machining fluid to the grinding operation section.

[Embodiment] Fig. 1 shows an embodiment of the present invention, in which numeral 11 is a shank, the diamond grinding wheel portion at the tip of which has a cylindrical portion 12 with a nominal diameter and a truncated conical portion 13 following this.
It consists of. Broken lines 14, 15, and 16 indicate boundaries between the above-mentioned parts. A through hole 18 passing through the shank 11 and opening at the tip of the tool functions similarly to the through hole 4 in FIG. 5 for core separation and as a machining fluid spout. A horizontal hole 19 branching from the hollow part 18 is a truncated conical part 1.
It opens on the surface of 3.

In addition, Fig. 1 shows an example in which the diamond grinding wheel part is made by electrodeposition, and the tip of the shank 11 is processed into the above-mentioned drill shape to serve as the grinding wheel base metal, and the diamond abrasive grains 17 are fixed to the surface by the electrodeposition method. It has a similar structure.

Further, although FIG. 1 shows an embodiment configured as an electrodeposited diamond tool, this can also be made into a metal bonded diamond tool. At this time, the diamond grindstone portion 2 shown in FIG. 5 has the shape of the present invention. Electroplated tools are suitable for the core drill of the present invention because they have a simple manufacturing process, are easy to accurately form any shape, and have high grinding performance, but metal bond tools are better if tool life is important. Since wear and tear of a core drill is significant at the tool tip, it is also effective to configure the tip 23 with a metal bonded grindstone and the remaining parts 24 and 25 with electroplated grindstones as shown in FIG.

The shape of the tip of the diamond grindstone portion is not limited to the truncated conical shape shown by reference numeral 13 in FIG. In short, it is sufficient that a slope connecting the small diameter drill tip and the nominal diameter cylindrical portion is formed, for example, a morning glory shape 13a (FIG. 3) may be used.

Further, if an inclined portion 33 is provided above the cylindrical portion 32 having the nominal diameter as shown in FIG. 4, it is possible to chamfer the upper opening in addition to drilling in one operation from one side.

Parallel grooves or spiral grooves can also be carved in the diamond grindstone portion of the core drill of the present invention. It smoothes the flow of machining fluid through the gap between the inner wall of the hole being machined and the tool, and is effective in removing chips.

[Effects of the invention] The conventional method of machining from both sides to prevent chipping of the opening requires complicated machinery and operations, and the machining results often have defects such as misaligned holes, steps, or minute cracks. . The present invention can make a hole in a glass plate or the like by machining it from one side using a single tool, without any of the above-mentioned defects as well as the opening being chipped. In addition, in the conventional case, after the hole penetrated through the cutting machine, the pressurized liquid was squirted downwards, and the machining liquid was not supplied to the grinding operation part 13, which caused seizure, but the present invention has the disadvantage that Through hole 1 that penetrates to the tip of the drill
8 is a machining fluid spout port, and a horizontal hole 19 supplies the machining fluid to the grinding operation part even after the hole is penetrated, cooling it,
It is possible to maintain the effects of friction reduction and chip evacuation, and it has become possible to solve the conventional drawbacks.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional front view showing one embodiment of a diamond core drill according to the present invention, FIGS. 2 to 4 are front views showing modified examples, and FIG. 2 is a cross-sectional view. FIG. 5 is a longitudinal sectional front view of a conventional diamond core drill. 11...Shank, 12...Cylindrical part, 13...
truncated conical part, 18...through hole.

Claims (1)

[Scope of Claim for Utility Model Registration] A diamond core drill in which a diamond grinding wheel part provided at the tip of a steel shank consists of a combination of the following two elements a and b. (a) Consisting of a cylindrical part with a nominal diameter and an inclined part continuous with the tip of the cylindrical part that gradually reduces to end at a drill tip with a diameter smaller than the nominal diameter; (b) A through hole formed in the drill shaft center. A horizontal hole is provided that communicates with and opens to the inclined portion.