JPH03156091A - Core bit - Google Patents

Abstract

PURPOSE:To permit a dry boring operation stably by a method in which a scooping angle is formed in the direction of rotating a diamond segment for the first slit, and the second slit having the same scooping angle as that of the first slit whose scooping face is attached with a hard tip is provided. CONSTITUTION:An opening pierced to the inner face of an annular steel alloy 4 is formed in the base of a diamond segment and a scooping angle is formed in the direction of rotating a core bit 10 to form the first slit 1. A hard tip 5 is attached to the inner surface of the slit 1 for preventing the abrasion of the scooping face from which cut dust is removed out and also for obtaining a stable area. The second slit 2 having a scooping angle is formed over almost the whole length of the peripheral face of the alloy 4. Cut dust discharged through the slit 1 is continuously put on the scooping face of the slit 2 to remove it out. Dry boring operation can thus be attained without the need for air compressor, etc.

Description

[Detailed description of the invention] [Industrial application field] The present invention applies to concrete, asphalt, and stone.

This product relates to core bits for dry-type drilling of materials such as refractories, ceramics, tiles, and bricks.

[Conventional technology]

When drilling a hole in concrete or the like using a diamond core bit, cooling water or compressed air is generally jetted into the hole in order to cool the cutting edge of the bit and discharge chips.

When drilling holes in concrete or the like using a dry method that does not use cooling water or compressed air, it is necessary to use the rotation of the core bit to mechanically discharge chips to the outside.

Conventionally, various chip discharge mechanisms for discharge of chips from a core bit have been disclosed.

For example, Japanese Utility Model Application Publication No. 58-120292 discloses a method in which a spiral groove is formed on the side surface of an iron alloy and chips are discharged along the groove.

Further, Japanese Utility Model Application Publication No. 48-93469 discloses a structure in which strips of cemented carbide are spirally thermally sprayed and welded to the side surface of an iron alloy to guide chips.

Furthermore, Japanese Patent Laid-Open No. 56-89414 discloses a structure in which slits or holes are formed through the side surface of an iron alloy.

[Problem to be solved by the invention]

In general, when cooling water is used, the high-pressure cooling water has the function of pushing out chips, so there is not as much of a problem in terms of chip discharge. It becomes difficult for the chips to be discharged to the outside, and the cutting edge becomes clogged with chips, making it impossible to drill holes.

Therefore, in the case of a dry core bit, in order to discharge the generated chips, a force to rotate the chips around the alloy and a force to move them in the axial direction (raking force) are applied, and in addition, these It is necessary to have a structure with a chip discharge mechanism that can sustain the force of .

However, the chip discharge mechanism of conventional dry core bits is insufficient in terms of combining the power to rotate the chips, the force to move them in the axial direction of the alloy, and the effect of sustaining these discharge functions. There is a drawback.

The present invention solves the drawbacks of conventional bits, especially when used in dry drilling, and is designed to provide a dry drilling bit that is excellent in scraping out chips during dry drilling and that can maintain these effects over a long period of time. It provides bits.

[Means to solve the problem]

The core bit of the present invention is provided with a first slit and a second slit penetrating the pipe-shaped iron base of the core bit, and the first slit has an angle that is a rake angle with respect to the rotation direction of the diamond segment. The second slit overlaps the first slit in the length direction of the core bit and has a similar rake angle.

[Effect]

The concentration of chips generated by the drilling process is highest around the diamond segment near the cutting point. Since the first slit has a rake angle, the chips are sent to the outside in the opposite direction to the digging direction of the core bit. In addition, the carbide tip and delivery slit generate airflow as they rotate, thereby increasing the cooling effect of the cutting edge.

Furthermore, the chips sent out toward the outside in the direction opposite to the digging direction by the first slit are scraped out along the rake face of the second slit. Here, since both slits are through holes, even if chips enter the inner circumferential side of the core bit, they will eventually be ejected to the outer circumferential side due to centrifugal force.
It will be easily discharged.

〔Example〕

The present invention will be explained by means of embodiments shown in the accompanying drawings.

FIG. 1 is a side cross-sectional view of a dry core bit IO according to an embodiment of the present invention having a first slit 1 and a second slit 2. FIG.

Referring to the figure, the first slit l opens at the base of the diamond segment 30, penetrates toward the inner surface of the iron annular base metal 4, and is drilled to form a rake angle with respect to the rotational direction of the core bit 10. Similarly, the second slit 2 is also provided to penetrate through the side surface of the base metal 4.

The first slit 1 is 15au in the length direction of the core bit.
Two through holes a are provided around the entire circumference, and the width of the opening is preferably 4 to 5 mm, taking into account the width between the diamond chips and the strength of the iron alloy.

FIG. 2 is a diagram showing details of how the first slit 1 is formed.

This first slit 1 has a rake angle indicated by θ and opens at the base of the diamond segment 30.

Further, a carbide tip 5 is bonded within the slit 1 in order to prevent wear of the rake surface for scraping out chips and to obtain a stable area. Figure 3 shows the experimental results regarding the effect of this carbide tip.

Further, the second slit 2 has the same angle θ and is provided so as to penetrate substantially the entire length of the outer circumferential surface of the iron alloy 4.

Figure 4 shows the experimental results regarding the rake angle θ and the chip discharge effect. The value of θ is preferably 10 to 20 degrees, taking into account the discharge of chips and the strength of the iron alloy.

FIG. 5 shows the experimental results regarding the width of the slit 20 and the chip discharge effect. As a result, the width of slit 2 is 10 mm from 2 stops.
is fully effective.

The tip of the second slit 2 overlaps the first slit 1 in its length position, as shown in FIG.

This is because the chips scraped out by the slit 1 are continuously scraped out by placing them on the rake face of the slit 2, and normally this function is achieved when the degree of overlap is about 5M.

Test results of the dry core bit according to the embodiment of the present invention having the above shape are shown in FIGS. 6 and 7.

As comparative examples, (a) is one in which spiral grooves are formed on the outer peripheral surface of the alloy, and (b) is one in which strips of cemented carbide are formed spirally on the outer peripheral surface of the alloy. Also, (C)
shows an example in which only a through slit is provided in the axial direction on the side surface of the alloy.

FIG. 6 is a graph showing the relationship between drilling depth and drilling speed, and FIG. 7 is a graph showing the relationship between drilling depth and the amount of chips discharged.

The test conditions were as follows.

Test machine Hitachi Koki DC120 type core drill rated current
8A No-load rotation speed 1100 R0P9M.

Material to be drilled Concrete Compressive strength 250kg/cII Drilling method Dry holes are drilled vertically through the concrete.

Drilling length: 100mm x 10 drillings As can be seen from the test results, the core bit of this example is superior in chip removal compared to conventional products, and reduces the drilling speed even when the drilling length becomes longer. It has become possible to work efficiently without any hassle.

〔Effect of the invention〕

The core bit of the present invention can provide the following effects.

(1) Does not require equipment such as an air compressor,
It has become possible to dry drill holes in concrete, etc.

(2) Due to the use of wear-resistant materials in the chip discharge mechanism,
It is stable and can be used until the end.

[Brief explanation of the drawing]

Fig. 1 is a diagram showing a side cross section of a dry core bit according to an embodiment of the present invention, Fig. 2 is a diagram showing details of the formation state of the first slit, and Fig. 3 is a diagram showing experimental results regarding the effect of the carbide tip. Figure 4 is a diagram showing the experimental results regarding the rake angle and chip discharge effect, Figure 5 is a diagram showing the experimental results regarding the slit width dimension and chip discharge effect, and Figure 6 is the diagram showing the drilling depth and drilling effect. FIG. 7 is a diagram showing the relationship between the drilling depth and the amount of chips discharged. 1: First slit 2: Second slit 3: Diamond segment 4: Base metal 5: Carbide tip 10: Dry core bit

Claims (1)

[Claims] 1. A first slit and a second slit that are open on one side are provided in the pipe-shaped iron base of the core bit.
The first slit has a rake angle with respect to the rotational direction of the diamond segment, and a carbide tip is glued to the rake face, and the second slit has a length that is the same as that of the first slit and the core bit. A core bit that overlaps in the horizontal direction and also has a rake angle with respect to the direction of rotation of the diamond segment.