JP2017227022A - Cemented carbide tip and excavation tool using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cemented carbide tip which is fitted into a fitting hole of an excavation tool by press fitting or shrink fitting, and which can be removed from the excavation tool.SOLUTION: A cemented carbide tip 20 includes an approximately cylindrical body part 21 that is embedded in a fitting hole 13 of an excavation tool 10, and a tip 22 that is formed in such a shape that a central part swells on the tip side of the body part 21 and that is exposed on the outside of the fitting hole 13. A flat surface 25 extended in a height direction of the cemented carbide tip 20 is formed on a side surface of the cemented carbide tip 20. The flat surface 25 is formed almost in parallel with the axial center of the cemented carbide tip 20, and extended high enough to be exposed on the outside of the fitting hole 13 at the tip 22.SELECTED DRAWING: Figure 2

Description

  The present invention relates to an excavation tool using a cemented carbide tip.

  Conventionally, excavation tools using carbide tips such as rock bits are known. Patent Document 1 describes a cutter bit used for construction of a reinforced concrete pile buried in the ground.

  Specifically, the cutter bit described in Patent Document 1 has a steel shank attached to the tip of the rotating body and a substantially cylindrical cemented carbide tip that is press-fitted into an insertion hole of the steel shank. A substantially triangular side surface notch is formed in the substantially cylindrical side surface portion of the cemented carbide chip. The distance from the cylindrical central axis of the cemented carbide tip is smaller than the radius of the cylindrical rear end surface of the substantially triangular side on the front end side in the side cutout. Therefore, the inner surface of the insertion hole is pushed into the space between the inner surface of the insertion hole of the steel shank and the side cutout portion, and the cemented carbide chip can be firmly attached to the insertion hole.

Utility Model Registration No. 3201625

  By the way, conventionally, the cemented carbide tip attached to the excavation tool by shrink fitting or press fitting has been discarded without being removed from the excavation tool when the excavation tool reaches the end of its life. Under such circumstances, the inventors of the present application considered that it would be desirable to be able to recycle the cemented carbide chip by removing the cemented carbide chip from the excavation tool. However, while conventional carbide tips including the cemented carbide tip described in Patent Document 1 have been devised to firmly attach the carbide tips to the drilling tool, the carbide tips are removed from the drilling tool. It is not considered to be removed. Therefore, conventionally, it was not possible to remove the carbide tip from the excavation tool.

  This invention is made in view of such a situation, and provides the carbide | carbonized_material chip | tip which can be removed from a digging tool in the carbide | carbonized_material chip inserted in the fitting hole of a drilling tool by press-fit or shrink fitting. With the goal.

  In order to solve the above-mentioned problems, the first invention is a cemented carbide chip that is fitted into a fitting hole of a drilling tool by press-fitting or shrink fitting, and has a substantially cylindrical shape embedded in the fitting hole of the drilling tool. A main body part, and a tip part that is formed in a shape in which the center part bulges on the front end side of the main body part, and is exposed to the outside of the fitting hole. A flat surface extending in the direction is formed, and the flat surface is formed substantially parallel to the axis of the cemented carbide chip and extends to a height at which the tip is exposed to the outside of the fitting hole.

  In a second aspect based on the first aspect, the flat surface extends from the rear end of the main body portion to a height that is exposed to the outside of the fitting hole at the front end portion.

  3rd invention is an excavation tool provided with the cemented carbide tip of 1st or 2nd invention, and the head by which the cemented carbide chip was inserted by the fitting hole.

  In the first invention, a flat surface extending in the height direction of the cemented carbide chip is formed on the side surface of the cemented carbide chip. This flat surface is formed substantially parallel to the axis of the cemented carbide chip and extends to a height at which the tip is exposed to the outside of the fitting hole.

  Here, as for the conventional cemented carbide chip, as shown in FIG. 4C of Patent Document 1, the substantially triangular side surface notch portion formed on the side surface portion of the cylindrical portion is exposed outside the insertion hole. Absent. Therefore, the cemented carbide tip cannot be grasped by a tool such as pliers or pliers (hereinafter referred to as “pulling tool”), and the cemented carbide tip cannot be removed from the excavation tool. Further, as described above, the distance from the center axis of the columnar shape of the cemented carbide tip of the substantially triangular side on the front end side in the side cutout is smaller than the radius of the columnar rear end surface. In other words, the radius of the rear end surface of the cylindrical shape is larger than that of the front end side. Therefore, even if the cemented carbide chip can be grasped, when the cemented carbide chip is pulled out, the columnar rear end surface is caught on the inner surface of the insertion hole, and the cemented carbide chip cannot be pulled out.

  On the other hand, in the first invention, the carbide tip can be firmly grasped by grasping the flat surface of the carbide tip with a drawing tool or the like. Since the flat surface is formed substantially parallel to the axis of the carbide tip, the carbide tip can be pulled out from the excavating tool using a drawing tool or the like without the flat surface being caught by the inner surface of the fitting hole. Can do. Thereby, the recycling of the cemented carbide chip can be realized.

  In the second invention, a gap is formed between the flat surface of the cemented carbide chip and the inner surface of the fitting hole having a circular cross section. Here, if there is no gap, for example, when inserting the carbide tip into the depth of the fitting hole by press-fitting, the carbide resistance is received due to the air resistance between the bottom surface of the fitting hole and the carbide tip. It is not easy to insert the chip all the way into the fitting hole. On the other hand, in the second invention, air between the bottom surface of the fitting hole and the cemented carbide chip escapes from the gap. Therefore, it is possible to easily insert the cemented carbide chip to the depth of the fitting hole with almost no air resistance.

It is a block diagram of a drilling tool, (a) top view, (b) side view It is a block diagram of a cemented carbide chip, (a) front view, (b) rear view, (c) right side view, (d) left side view, (e) top view, (f) bottom view It is a block diagram of the cemented carbide chip concerning other embodiments, (a) front view, (b) back view, (c) right side view, (d) left side view, (e) top view, (f) ) Bottom view

  Hereinafter, embodiments of the present invention will be described in detail with reference to FIGS. The following embodiment is an example of the present invention, and is not intended to limit the scope of the present invention, its application, or its use.

[1. About drilling tools]
The excavation tool 10 is a metal tool used for excavation work (for example, tunnel work). As shown in FIGS. 1A and 1B, the excavation tool 10 is a rock bit in which a plurality of carbide tips 20 are embedded. In FIG. 1, the carbide chip 20 is hatched. The excavation tool 10 is not limited to a rock bit, and may be another type of excavation tool.

  As shown in FIG. 1B, the excavation tool 10 includes a head portion 12 and a skirt portion 14 that is continuous with the rear side of the head portion 12. A plurality of fitting holes 13 are formed in the front end surface 12 a and the outer peripheral inclined surface 12 b of the head 12. Each fitting hole 13 is a hole having a circular cross-sectional shape. That is, each fitting hole 13 has a cylindrical inner surface. A carbide chip 20 is fitted into each fitting hole 13 by shrink fitting or press fitting. Details of the carbide tip 20 will be described later. Further, a face hole 24 (a hole for cooling water) connected to a screw hole described later is formed in the head 12.

  The skirt portion 14 is formed with a screw hole (not shown) opened in the rear end face. The rod of the drilling machine is screwed into this screw hole. Thereby, the rotational force and impact force from the drilling machine can be transmitted to the excavation tool 10, and excavation using the excavation tool 10 becomes possible.

[2. About carbide tips]
The cemented carbide tip 20 is a tip made of a cemented carbide alloy with a rounded tip. As shown in FIGS. 2A to 2F, the cemented carbide chip 20 has a main body portion 21 embedded in the fitting hole 13 of the excavation tool 10, and a center portion bulges on the distal end side of the main body portion 21. And a tip portion 22 that is formed in a shape and is entirely exposed outside the fitting hole 13.

  The main body 21 is formed in a substantially cylindrical shape with a part of the side surface 21a cut out. The main body 21 is formed in a uniform cross section (that is, the diameter is uniform) except for the rear end 21b. The diameter of the main body 21 is slightly larger than the diameter of the fitting hole 13. On the other hand, the distal end portion 22 is continuously formed on the distal end side of the main body portion 21. The tip portion 22 is formed in a substantially hemispherical round shape except for a portion cut out together with the main body portion 21. In the cemented carbide chip 20, the height at which the diameter starts to decrease is the boundary between the main body portion 21 and the tip portion 22.

  As shown in FIGS. 2B to 2D, a flat surface 25 extending in the height direction is formed on the side surface 21 a of the main body 21. The flat surface 25 is formed substantially parallel to the axis of the main body 21. As shown in FIG. 2B, in the main body 21, the width W of the flat surface 25 is uniform over the height direction. The flat surface 25 extends from the rear end of the main body portion 21 to a height at which the front end portion 22 is exposed to the outside of the fitting hole 13. That is, the flat surface 25 extends to the distal end portion 22 beyond the upper end of the main body portion 21. The flat surface 25 may be formed not from the rear end of the main body 21 but from the middle of the main body 21.

  Of the flat surface 25, a portion 25a formed at the tip 22 has a width W and a height H2 that can be grasped by a drawing tool. For example, the width W is preferably 5 mm or more and the height H2 is preferably 2 mm or more. The flat surface 25 is formed by cutting with a diamond cutter, for example.

  An example of the dimension of the cemented carbide chip 20 is shown. The main body 21 has a diameter of 18 mm and a height of 16 mm. The tip 22 has a height of 8 mm. The distance from the axial center of the main body 21 to the center position in the width direction of the flat surface 25 is 1 mm (that is, the cutting thickness by the diamond cutter is 1 mm). The flat surface 25 has a width W of about 8 mm and a height H1 of about 18.5 mm (of which the height H2 of the portion 25a formed at the tip 22 is about 2.5 mm). The present invention is not limited to these dimensions. Further, the flat surface 25 may be formed when a flat surface corresponding to the flat surface 25 is formed on the mold for the cemented carbide chip 20 and the cemented carbide chip 20 is sintered in the mold.

[3. Attaching and removing carbide tips]
First, a method for attaching the carbide tip 20 to the fitting hole 13 of the head 12 will be described.

  The carbide chip 20 is fitted into the fitting hole 13 by shrink fitting or press-fitting. Specifically, when the cemented carbide tip 20 is attached to the head 12, in the case of shrink fitting, the head 12 is heated and expanded to about 400 to 600 ° C., for example, and the fitting hole 13 is expanded. In this state, the cemented carbide chip 20 is inserted to the back of the fitting hole 13. Thereafter, when the temperature of the head 12 decreases, the inner surface of the fitting hole 13 is pressed against the outer surface of the main body portion 21 as the head 12 and the fitting hole 13 contract. As a result, the cemented carbide chip 20 is firmly fitted into the fitting hole 13. On the other hand, in the case of press-fitting, the diameter of the carbide tip 20 is formed, for example, 1.02 to 1.03 times as large as the diameter of the fitting hole 13 (for example, 13 mm), and the carbide tip 20 is inserted into the fitting hole 13. In accordance with the position, the carbide chip 20 is press-fitted into the fitting hole 13 by pressing. In the present embodiment, the height of the main body 21 is slightly larger than the depth of the fitting hole 13. In the cemented carbide chip 20, substantially the entire body portion 21 is embedded in the fitting hole 13, but only a part on the tip side is exposed to the outside of the fitting hole 13.

  In the present embodiment, a relatively large gap (a gap having a uniform cross section in the depth direction) is formed between each flat surface 25 of the cemented carbide chip 20 and the inner surface of the fitting hole 13. Here, when there is no gap, for example, when inserting the carbide tip 20 into the fitting hole 13 by press-fitting, the resistance of the air between the bottom surface of the fitting hole 13 and the carbide tip 20 is received, It is not easy to insert the carbide tip 20 to the back of the fitting hole 13. On the other hand, in the present embodiment, the air between the bottom surface of the fitting hole 13 and the cemented carbide chip 20 escapes from the gap. Therefore, the cemented carbide tip 20 can be easily inserted to the back of the fitting hole 13 with almost no air resistance during press-fitting.

  Next, a method for removing the carbide tip 20 from the fitting hole 13 of the head 12 will be described.

  When removing the cemented carbide tip 20, for example, the head 12 is heated and expanded to about 700 ° C., and the fitting hole 13 is expanded. And the carbide | carbonized_material chip | tip 20 can be firmly grasped by grasping the flat surface 25 and its opposing part among the front-end | tip parts 22 of the carbide | carbonized_material chip | tip 20 with a drawing tool. Since the flat surface 25 is formed substantially parallel to the axis of the cemented carbide tip 20, the cemented carbide tip is removed from the excavation tool 10 using a drawing tool or the like without the flat surface 25 being caught on the inner surface of the fitting hole 13. 20 can be pulled out. Thereby, recycling of the cemented carbide chip | tip 20 is realizable.

[4. Other Embodiments]
In the above embodiment, the shape of the tip 22 of the cemented carbide tip 20 is substantially hemispherical. However, the tip is not limited to this shape, and the tip is not limited to the cemented carbide chip described in Patent Document 1. The tip of 22 may be sharp.

  Moreover, in the said embodiment, as shown to Fig.3 (a)-(f), you may form a pair of flat surface 25 which mutually opposes on the side surface of the cemented carbide chip 20. FIG. Each flat surface 25 is formed to a height that is exposed to the outside of the fitting hole 13 at the distal end portion 22 substantially parallel to the axis of the carbide chip 20.

  The present invention can be applied to a case using a carbide chip.

DESCRIPTION OF SYMBOLS 10 Excavation tool 13 Fitting hole 20 Carbide tip 21 Main-body part 22 Tip part 25 Flat surface

Claims (3)

A cemented carbide chip that is fitted into a fitting hole of a drilling tool by press fitting or shrink fitting,
A substantially cylindrical body portion embedded in the fitting hole of the excavation tool;
A center part is formed in a shape that bulges on the tip side of the main body part, and includes a tip part exposed outside the fitting hole,
A flat surface extending in the height direction of the cemented carbide chip is formed on the side surface of the cemented carbide chip,
The cemented carbide chip according to claim 1, wherein the flat surface is formed substantially parallel to the axis of the cemented carbide chip, and extends to a height exposed to the outside of the fitting hole at the tip.   The cemented carbide chip according to claim 1, wherein the flat surface extends from a rear end of the main body portion to a height at which the front end portion is exposed to the outside of the fitting hole. The cemented carbide chip according to claim 1 or 2,
An excavation tool comprising: a head in which the carbide tip is fitted in a fitting hole.

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