JP2002081287A - Composite bit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make a composite bit suitable for the hard ground, and improve excavating efficiency by slowing abrasion of the outermost peripheral tip contacting with a hole wall while improving the excavating efficiency when using a cylindrical tip such as a spike tip, a high speed tip and a button tip for a conventional boring bit, and restraining the abrasion to a certain degree when using a roof bit for the bit. SOLUTION: Tips are implanted outward from the inside on the tip of the bit 50 so that the tip draws plural concentric circles around the axis O, the outermost peripheral tip is composed of a cutter tip 51, and other than that is composed of the cylindrical tip 52. The tip of the cutter tip 51 is positioned in the rearmost part separate in the shaft direction by a distance L of 0.2d to 1d of a diameter d of the cylindrical tip 52 from the forefront end, of the most projected cylindrical tip 52, and an outward projecting width b from a bit outer diameter 53 of the concentric circles drawn by the cutter tip 51 becomes 0.2w to 0.6w of a cutter tip width w.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a compound bit for boring used in civil engineering works and ground surveys.

[0002]

2. Description of the Related Art FIG. 4 is a diagram of a conventional outer bit for excavating a double pipe, in which only a spike tip 11 is implanted in a bit 10, and the outermost spike tip 11 is indicated by a chain line D. As shown in the figure, the bit slightly protrudes outward from the bit outer diameter 12, so that the bit outer diameter 12 does not directly contact the hole wall during drilling, so that rotation resistance and wear of the bit outer diameter are reduced. ing.

However, in the case of a cylindrical tip such as a spike tip and other high-speed tips, button tips, and chisel tips shown in FIG. 1, the protruding volume from the bit outer diameter 12 is small, and the time to reach the wear limit is short. .

FIG. 5 shows a bit 20 in which a roof tip 21 is implanted. In this case, the projecting volume of the bit 20 from the main body to the excavation surface is larger than that of the cylindrical tip, and the time to reach the wear limit is longer. However, the excavation efficiency was poor because the tip area of the tip in contact with the excavation surface was large.

FIG. 6 is a view of a bit 30 for drilling reinforced concrete. In order to cut a reinforcing bar, a tip 31 of a cutting blade slightly projecting in and out is implanted. It was about 15% of that, and even if it was applied to the bedrock, it had little effect on the wear and efficiency of the bit 30.

FIG. 7 shows a core extracting bit 40, in which a cutter type tip 41 protrudes on the inner diameter side, but it is difficult to apply this as it is on the outer diameter side.

[0007]

The problem to be solved is that when a cylindrical tip is used for the conventional bit, the drilling efficiency is good but the outermost tip that comes into contact with the hole wall wears quickly and the bit is a roof bit. Although the use of the steel reduced the wear to some extent, it was unsuitable for hard ground and the excavation efficiency was poor.

[0008]

According to the present invention, in order to solve the above-mentioned problems, the bit is a compound bit, and the tip of the bit draws a plurality of concentric circles at the time of excavation with respect to the axis on the excavation surface at the tip of the bit. The tip is implanted on the outer circumference from near the axis, the outermost concentric tip is a cutter type, the other concentric tip is a cylindrical tip, and the tip of the cutter type is the most protruding cylindrical shape. From the tip of the tip, 0.2d of cylindrical tip diameter d ~
1d, which is located rearmost in the direction of the distance axis, and the width b of the concentric circle drawn by the cutter tip from the bit outer diameter to the outside is 0.2w to 0.6w of the cutter tip width w, In addition, the tip of the tip drawing the concentric circle has a predetermined protrusion height difference from the axial tip of the cylindrical tip to the cutter tip.

[0009] Since only the outermost concentric circular tip is a cutter type and has a large protrusion width from the bit outer diameter to the outside, the bit wear is small and the drilling efficiency is good.

Further, the tip of the cylindrical tip at the axially leading end of the composite bit of the present invention forms an innermost concentric circle, and the tip is disposed concentrically outside the tip, and the tip is disposed in the forward and backward directions. The angle α formed by the conical surface circumscribing each concentric circle and the axis at the vertex is 30 degrees to 60 degrees.

The shape of the tip contacting the excavation surface is not flat, but is inclined in the axial direction. The bit has little deflection during excavation, and the bit penetrates in the axial direction, so excavation efficiency is good. .

In the composite bit of the present invention, the tip of the mountain of the cutter tip of the composite bit is offset forward in the rotation direction, and the angle between the left and right slopes of the mountain and the vertical surface lowered from the tip is such that the front angle γ is the rear. Is smaller than the angle δ.

Since γ corresponds to the rake angle in a metal cutting tool, the smaller the value, the lower the excavation resistance.

The vertical dimension between the tip of the peak of the cutter tip and the bottom face of the composite bit of the present invention is preferably 0.8 w to 2 w, which is the width w of the cutter tip.

Further, the hardness of the cutter tip of the composite bit of the present invention is higher than the hardness of the cylindrical tip.

Since the cylindrical tip is easily broken, it is made of a cemented carbide having a lower hardness than the cutter tip and a higher resistance. The cutter tip for mainly cutting the wall surface is hardly chipped in shape, so the resistance is low but the hardness is low. If it is made higher, it will withstand wear and its life will be longer.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a diagram of a composite bit showing an embodiment of the present invention, and shows an outer bit 50 for double pipe excavation. FIG. 3 is a composite bit diagram showing another embodiment of the present invention, in which a retract bit 60 is shown.

The present invention is applicable not only to the outer bit shown in FIG. 1 and the retract bit shown in FIG. 3, but also to all bits for drilling holes in the ground, such as a core bit and a bit for full-scale excavation.

In the outer bit 50 shown in FIG.
On the other hand, the tip of the outermost periphery where the tip draws a concentric circle is the cutter tip 51, and the tip where the tip draws a concentric circle inside is the high-speed tip 52, and the retract bit 60 shown in FIG. (B) is the same.

FIG. 2 shows the tip of the cutter tip 51.
As shown in (2), the tip of the high-speed chip 52 is located at a distance of 0.2d to 1d of the chip diameter d in the L-axis direction and at the rearmost position.

As shown in FIGS. 2 (a) and 1 (b), the high speed chip 52 does not need to have the innermost one projecting the most, and depending on the state of the ground, as shown in FIG. 1 (c). The high-speed tip 52 in the middle may protrude most, and the axial distance between the tip and the cutter tip 51 may be L.

The tip of the tip drawing a concentric circle extends from the high-speed tip 52 in the axial direction to the cutter tip 51, and has a predetermined difference in protrusion height, that is, L1 and L2 as shown in FIG. Have. The above configuration is the same for the retract bit 60 shown in FIG.

Further, as shown in FIG. 2A, the bit outer diameter 53 of a concentric circle drawn by the cutter tip 51 (in this case, the high-speed chip is slightly outside the bit by design, so Is referred to as a bit outer diameter 53).
w to 0.6 w, and this dimension is effective in design and wear resistance. This configuration also corresponds to the retract bit 60 shown in FIG.
The same applies to

Next, FIGS. 1A and 1B and FIG. 2A
As shown in FIG.
Form an innermost concentric circle, and a tip is disposed rearward in order to draw a concentric circle on the outer side, and an angle between a conical surface 54 circumscribing each concentric circle and an axis O at a vertex 54a is α. When the angle α is set in the range of 30 to 60 degrees, the swing of the bit at the time of excavation is small, and the drill bit goes straight in the axial direction, so that the excavation efficiency is good. The above configuration can be applied to the retract bit shown in FIG.

Next, regarding the shape of the cutter tip 51, in the examples shown in FIGS. 2B and 2C, the angled tip 51a of the cutter tip 51 is moved forward in the rotation direction B (FIG. 1A). The angle between the left and right slopes 51b and 51c and the vertical surface 51d lowered from the tip 51a is formed so that the front angle γ is smaller than the rear angle δ. (The rake angle in the case of a metal cutting tool) is reduced, and therefore the cutting resistance is reduced.

Next, regarding the dimensions of the cutter tip 51,
As shown in FIG. 2, the tip 51a of the peak of the cutter tip 51
The vertical dimension C between the bottom and the bottom surface 51e is the cutter tip width w.
When 0.8 w to 2 w is obtained, good results can be obtained in terms of the planting strength on the bit body and the wear due to friction with the inner wall of the ground.

The hardness of the cutter tip 51 is preferably higher than that of the high-speed tip 52 (cylindrical tip). That is, since the cylindrical tip mainly excavates the excavation surface and easily breaks, it is better that the resistance is large even if the hardness is low, and the cutter tip 51 mainly comes into rotational contact with the wall surface of the hole rather than the excavation, so that the resistance is low. It is better not to need much force and high hardness.

[0028]

According to the present invention described in detail above, the following effects can be obtained.

(1) The excavation is performed with a cylindrical tip having good excavation efficiency, and the contact with the hole wall is made with a cutter tip so that the protrusion width of the cutter tip to the wall surface can be increased. Therefore, the life of the bit can be maintained without lowering the excavation efficiency. Can be extended.

(2) Since the surface circumscribing the concentric circle formed by the tip of the tip is formed in a conical shape, the center of the bit at the time of excavation is small and the excavation efficiency is good.

(3) Since the tip of the chevron of the cutter tip is offset toward the tip in the rotation direction, and the angle between the front slope and the vertical plane is smaller than the angle between the rear slope and the vertical plane, the excavation resistance is small.

(4) By making the hardness of the cutter tip harder than other cylindrical tips, wear is reduced and the life of the bit is extended.

[Brief description of the drawings]

FIGS. 1A and 1B are diagrams of an outer bit showing an embodiment of the present invention, wherein FIG. 1A is a plan view, FIG. 1B is a longitudinal section, and FIG. Are respectively shown.

FIG. 2 is an arrangement view of the chip of FIG. 1 and an enlarged explanatory view thereof.
(A) is a partially enlarged cross section, (b) is a side surface of the cutter tip portion of (a), and (c) is a plane of a cutting edge of the cutter tip as viewed from the line AA of (a).

3A and 3B are plan views of a retract bit according to another embodiment of the present invention, wherein FIG. 3A shows a closed state, and FIG. 3B shows an expanded state at the time of excavation.

4A and 4B are diagrams of a conventional spike chip type outer bit, in which FIG. 4A shows a plane and FIG. 4B shows a longitudinal section.

FIGS. 5A and 5B are views of a conventional roof chip type outer bit, in which FIG. 5A shows a plan view and FIG. 5B shows a half sectional front view.

6A and 6B are diagrams of a conventional reinforcing bit, wherein FIG.
(B) shows a front surface of a half section, respectively.

FIGS. 7A and 7B are diagrams of a conventional core bit, wherein FIG.
(B) shows the front, respectively.

[Explanation of symbols]

 Reference Signs List 50 outer bit 51 cutter tip 51a tip 51b, 51c inclined surface 51d vertical surface 51e bottom surface 52 high-speed chip 53 bit outer diameter 54 conical surface 60 retract bit O axis center B rotation direction C vertical dimension L1, L2 Difference in protrusion height

Claims (5)

[Claims] A tip is implanted on the outer periphery of the bit from the vicinity of the axis so that the tip of the tip draws a plurality of concentric circles at the time of excavation with respect to the axis, and the outermost concentric circle is drawn. Is a cutter type, and the other concentric tip is a cylindrical tip, and the tip of the cutter type has a distance axis of 0.2d to 1d of the cylindrical tip diameter d from the tip of the most protruding cylindrical tip. The cutter tip width w is located at the rearmost position in the rearward direction, and the width b of the concentric circle drawn outward from the bit outer diameter is 0.2 w to 0.6 w of the cutter tip width w, and the concentric circle is drawn. A composite bit, wherein the tip of the tip has a predetermined protrusion height difference from the axial tip of the cylindrical tip to the cutter tip. 2. The tip of the cylindrical tip at the axial end forms an innermost concentric circle, and the tip draws a concentric circle outside the tip, and the tips are sequentially arranged rearward, and circumscribes the respective concentric circles. The angle α between the conical surface and the axis at the vertex is 3
The composite bit according to claim 1, wherein the angle is 0 degree to 60 degrees. 3. The angled tip of the angle of the cutter tip is offset forward in the rotational direction, and the angle between the left and right slopes of the angle and the vertical surface lowered from the edge is such that the forward angle γ is smaller than the rearward angle δ. The composite bit according to claim 1, wherein: 4. The composite chip according to claim 1, wherein a vertical dimension between a tip of the mountain and a bottom surface of the cutter chip is 0.8 w to 2 w of a cutter chip width w. . 5. The hardness of the cutter tip is higher than the hardness of the cylindrical tip.
5. The composite chip according to 2, 3, or 4.