Moil point tool and crushing method using same

Abstract

To provide a moil point tool for crushing, which has a sharp tip and is easy to pierce into an object, has excellent crushing power for hard rock or the like, and is suppressed from experiencing a decrease in crushing power due to the internal pressure in a pilot hole or dust.SOLUTION: Provided is a moil point tool having a rod-shaped tool body, a tip portion that is chamfered into a triangular pyramid shape at the tip of the tool body, and a shank portion at the other end of the tool body.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a moil point tool having a triangular pyramid-shaped tip. A moil point tool is a tip tool with a pointed tip of a rod used for crushing rock, rock, concrete structures, concrete paving slabs, etc. by impact. The object is crushed by inserting the tip of the tool into a downhole and striking it so as to pierce the downhole.

Background Art

[0002] Conventionally, when crushing rock or concrete structures, various impact tools are used, from large to small handy types such as hydraulic impact tools that utilize the main power source of a hydraulic excavator, air impact tools using compressed air, and electric impact tools. A steel crushing tool is attached to the tip of the impact tool, and the object is crushed by striking the object. The crushing tools attached to the impact tools include a wedge point (horizontal single-character shape) with a flat tip of a steel rod (wedge-shaped in side view), a cone rod with a conical tip, a moil point tool with a tip of a rod pointed in a square pyramid shape, and a flat end with a non-pointed tip.

[0003] When it comes to the hardest rock, crushing with an impact crushing tool is not always easy, and it is difficult to efficiently crush the object. Therefore, before crushing, a downhole is provided by drilling a hole in a desired location of the object with a drill in advance. The impact tool is operated with the tip of the tool inserted into the downhole, and the object is crushed by striking so as to apply an impact from the tool tip toward the periphery of the downhole. However, even with a moil point tool with a pointed tip, sufficient crushing efficiency has not been obtained.

[0004] The moil point tool is formed by polishing the tip of a round steel bar chamfered from four directions to make it pointed in a square pyramid shape. This is because in manufacturing, if the front and back directions are polished first and then the left and right directions are polished, the polishing is easy and the processing is easy in terms of work.

[0005] Furthermore, a device has been proposed in which a narrow slit-shaped groove is provided from the tip of the tool toward the rod body (see, for example, Patent Gazette 1). By increasing the surface area, a deeper heat treatment depth is formed, aiming to improve the crushing performance and extend the lifespan.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0007] Crushing with an impact tool involves vibrating the crushing tool in the front - rear direction and repeatedly applying impacts to the object to promote crushing. Particularly for objects that are difficult to crush, such as hard rock formations, a pilot hole is drilled in advance, and the tool inserted into the pilot hole uses the pilot hole as a guide hole and bites deeper into the object through repeated impacts. However, since the diameter of the pilot hole is smaller than the diameter of the rod, when a square - pyramid - shaped moil point is stabbed into the pilot hole, the square pyramid has many contact points and a small gap with the pilot hole, so it is almost in a state of being blocked.

[0008] Then, when the tip of the tool bites into the object, in addition to the contact surface acting as a resistance, when the air containing small pieces and dust crushed by the impact of the blow is compressed, it is difficult to be discharged from the gap of the pilot hole. As a result, the pressure inside the pilot hole increases, preventing the tool from biting downward and reducing the crushing efficiency. And if the crushed dust clogs the inside of the pilot hole, the crushing will not proceed easily. If it bites in and clogs, the tool will get stuck and stop moving, so the crushing operation cannot be repeated, and the crushing work has to be interrupted until it is removed and redone. Thus, when the tools get stacked, it takes extra effort to remove them.

[0009] Therefore, the conventional moil point tool is a square pyramid, which is divided into four parts along the ridge line of the hypotenuse of the square pyramid. Although it is said to have excellent crushing force, due to the increase in internal pressure in the lower hole, crushing is difficult to progress, and dust is also difficult to discharge. That is, in the case of a square pyramid, the crushed dust is likely to accumulate and block in the lower hole, which tends to hinder the progress of crushing. Also, since it is divided and expanded in four directions, cracks occur in the cross direction, so it is difficult to control the direction of crushing. That is, since the crushing direction is affected by the four corners of the moil point, it is twisted crosswise, making it difficult to control in the intended direction.

[0010] If slits are provided from the tip to the rear at the center of the four faces of the square pyramid, it will promote the discharge of air and reduce the internal pressure. However, in order to provide the slits, extra processing such as cutting grooves is required. Since the moil point tool repeats impacts, the tip gradually wears. Therefore, every time the tip of the rod wears, it is necessary to reprocess the grooves inevitably. Thus, only slit processing is vulnerable to the influence of wear, so it cannot be said to be a sufficient stable countermeasure.

[0011] Therefore, the problems to be solved by the present invention are to provide a moil point tool for crushing that has a sharp tip and is excellent in crushing force against hard rock formations and the like, while suppressing a decrease in crushing ability due to internal pressure and dust in the lower hole. Another problem is to provide a moil point tool for crushing that is easier to control the direction of crushing than in the prior art.

Means for Solving the Problems

[0012] Therefore, as a result of intensive studies, the inventor of the present invention has found that even with a tool having a sharpened tip, in the case of a cone or a square pyramid, the contact with the lower hole is large, the pressure inside the lower hole is difficult to discharge, the biting force is attenuated, and the crushing force is inferior. On the other hand, when the tip of a rod-shaped bar (circular or hexagonal cross-section) is sharpened into a triangular pyramid shape, the contact points are few and the gap is large, so it is easy to discharge the crushed pieces, and even if the tip of the rod is slightly worn, it is not easily affected. Also, it has been found that the crushing direction is easier to control with a triangular cross-section.

[0013] That is, a first means for solving the problems of the present invention is a moil point tool including a rod-shaped tool body portion, a tip portion chamfered into a triangular pyramid shape at the tip of the tool body portion, and a shank portion at the other end of the tool body portion. A steel tool with the tip of the rod chamfered from three directions to form a triangular pyramid shape is easy to bite because the tip is sharp.

[0014] The second means is the moil point tool according to the first means, wherein the cross-sectional shape of the tip portion chamfered into a triangular pyramid shape is an equilateral triangle.

[0015] The third means is the moil point tool according to the first means, wherein the cross-sectional shape of the tip portion chamfered into a triangular pyramid shape is an isosceles triangle with the base longer than the equal sides.

[0016] The fourth means is the moil point tool according to the first means, wherein the cross-sectional shape of the tip portion chamfered into a triangular pyramid shape is an isosceles triangle with the base shorter than the equal sides.

[0017] In addition, an axial slit may be provided from the chamfered portion of the moil point tool of the first to fourth means toward the main body portion, in combination with the triangular pyramid shape. In addition to sufficiently hardening the surface by heat treatment, the pressure and dust inside the lower hole can be more effectively discharged.

[0018] The fifth method is a method of crushing an object by the impact motion of a moil point tool having a tip portion chamfered in a triangular pyramid shape according to any one of the first to fourth methods. After drilling a large number of pilot holes with a diameter of 2 / 5 to 3 / 5 of the outer diameter R of the tool body of the moil point tool at intervals of 2 to 4 times the outer diameter R of the tool body in a row on the surface of the object, the tip portion of the moil point tool is sequentially inserted into the pilot holes close to the end of the object, and the object is sequentially crushed by repeating the crushing operation by the impact motion. This is a crushing method using a moil point tool.

[0019] The sixth method is a crushing method using the moil point tool according to the fifth method, characterized in that the orientation of the tip of the moil point tool inserted into the pilot hole is such that a point where one of the hypotenuses of the triangular pyramid contacts the pilot hole is arranged on the end side of the object, and a straight line connecting the contact points between the remaining two hypotenuses and the object is parallel to the row of adjacent pilot holes.

[0020] The seventh method is a crushing method using the moil point tool according to the fifth method, characterized in that the orientation of the tip of the moil point tool inserted into the pilot hole is such that a point where one of the hypotenuses of the triangular pyramid contacts the pilot hole is arranged at the farthest position from the end side of the object, and a straight line connecting the contact points between the remaining two hypotenuses and the object is parallel to the row of adjacent pilot holes.

Advantages of the Invention

[0021] Since the tip of the moil point tool of the present invention is sharpened into a triangular pyramid shape, there are few contact points with the lower hole, only the apex of the triangle, and the gap with the circle of the lower hole is large. Therefore, there is room to allow air, crushed pieces, and dust in the lower hole to escape. Thus, it is difficult for the pressure that resists the operation of biting into the object due to the impact of the moil point tool to increase, so the tip of the moil point tool can penetrate deeply into the lower hole. In addition, since the crushed pieces and dust are easily discharged, the stack phenomenon in which the tip of the moil point tool remains clogged while biting into the lower hole of the object is reduced, and the crushing operation can continue. Therefore, deep and continuous crushing can be performed, resulting in a high crushing effect.

[0022] When using the moil point tool with the tip of the present invention on a triangular pyramid, the moil point tool can enter deeply and largely from the lower hole. Therefore, the object becomes large crushed pieces and is easily cracked, and the amount of dust generated is also reduced. In addition, since the moil point tool is suppressed from being bounced back by the pressure in the lower hole, the pushing pressure can be small, so the rod can be efficiently advanced deeply along the lower hole. The amount of flying rock scattered caused by inappropriate diving and bouncing back during pushing is also reduced. In addition, since the moil point advances along the lower hole, the chisel is difficult to slip and is easy to control. In addition, unnecessary vibration and noise can be suppressed, so the impact sound is difficult to increase.

[0023] If one of the vertices of the triangle formed by the contact point of the moil point tool inserted into the lower hole of the object is arranged on the free end face of the end of the object, and the line passing through the remaining two vertices is parallel to the row direction of the adjacent lower holes, and the triangle is to bite into the lower hole, when the tool enters deeply due to the impact of the moil point tool, the distance between the vertex close to the free end face and the remaining two vertices will expand. Then, the cracks from the two vertices to the adjacent lower holes are promoted, so the crushing efficiency is promoted.

[0024] One of the vertices of the triangle formed by the contact point of the moil point tool inserted into the lower hole of the object is arranged at a position directly opposite and farthest from the free end face of the end of the object, and the line passing through the remaining two vertices is made parallel to the column direction of the adjacent lower holes. Then, when the triangle is to bite into the lower hole, the tool will penetrate deeply by the impact of the moil point tool, and the distance between the vertex farthest from the free end face and the remaining two vertices will expand. Then, the cracks from the two vertices to the adjacent lower holes will be promoted, so the crushing efficiency will be promoted.

Brief Description of the Drawings

[0025]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Modes for Carrying Out the Invention

[0026] Embodiments of the moil point tool of the present invention will be described as appropriate with reference to the drawings. The moil point tool (1) of the present invention shown in Fig. 1 is formed into a triangular pyramid shape by chamfering the tip (2) of the rod body portion (4) of the bar steel sharply. The chamfered portion (3) is cut by grinding and the surface is polished as appropriate. The handle at the other end of the rod body portion (2) is provided with a shank portion (5) connected to an impact tool.

[0027] The material of the moil point tool of the present invention is steel, and the material of ordinary moil point tools can be applied. Since it is prone to wear, it is preferably carbon steel suitable for hardening treatment by heat treatment such as quenching and tempering. Further, considering the heat treatability, special steels such as chromium molybdenum steels such as SCM435 and SCM440 may be used. In this way, if the surface of the triangular pyramid-shaped moil point tool is hardened by heat treatment, it has excellent wear resistance and can be repeatedly crushed.

[0028] The outer diameter size of the rod body portion (2), the slit grooves with uneven shapes such as anti-rotation around the shank portion (5), etc. can be appropriately set to match the size and type of the impact tool to be used (from large hydraulic type to handy type).

[0029] The cross-section of the bar steel of the rod body portion (4) is circular or hexagonal. For example, as an example of the moil point tool (1) used for a handy type impact tool, taking a bar material with an outer diameter of 18 mm and a total rod length of 300 mm, the initial length of the tip portion (2) is 55 mm, and the chamfered portions (3) of the three chamfered sides of the triangular pyramid shape are each inclined by about 10 degrees from the axis center line of the rod. The crushing force of the moil point tool is concentrated at the tip of the triangular pyramid-shaped tip portion (2) formed by these inclinations.

[0030] Even when the outer diameter of the steel rod is thicker, a triangular pyramid-shaped tip portion can be formed by providing a chamfered portion with an inclined surface of about 10 to 15 degrees at the tip portion.

[0031] In the case of a conventional chamfered point tool in the shape of a square pyramid, when the rod has the same outer diameter of 18 mm and the overall length of 300 mm, the inclination of the surfaces of the four chamfered parts provided at every 90 degrees at the tip is about 10 degrees from the axial center line, and the initial length of the tip is about 50 mm. Therefore, the inclination of the tip of the triangular pyramid of the present invention can ensure an inclination angle similar to that of the conventional chamfered point tool, and in terms of the biting property into the pilot hole, it is equal to or better than that of the conventional tool, and the inclination of the chamfered part does not at all hinder biting or rock breaking.

[0032] The object that the present invention intends to crush is a hard object such as a concrete structure, a concrete paving slab, a rock formation, or a rock that is not easily crushable. Therefore, a pilot hole smaller than the outer diameter of the rod is drilled to a depth of about 100 mm with a drill or the like, and the sharp tip of the chamfered point tool is inserted into the pilot hole. Since the chamfered point tool strikes the object forcefully with an impact tool, the chamfered point tool is made to penetrate deeply into the concrete or the rock formation using the pilot hole as a guide, and the object is crushed by impact while being expanded from the pilot hole.

[0033] The size of the pilot hole of the object is smaller than the outer diameter of the rod of the chamfered point tool, and the load during drilling with a drill also increases. Therefore, the outer diameter of the pilot hole is about 1 / 3 to 3 / 4, preferably about 2 / 5 to 3 / 5, and preferably about 1 / 2 as a guideline, with respect to the outer diameter of the rod. When the outer diameter of the pilot hole is half the size of the outer diameter of the rod, when the rod penetrates deeply, it is expanded to four times the area of the pilot hole. Therefore, if it can penetrate deeply, it will lead to a very large crushing force.

[0034] When the tip of the chamfered point tool inserted into the circular pilot hole is a square pyramid and when it is a triangular pyramid, the clearance space secured around the tool is different. The tip inserted into the pilot hole is further pushed deeper by impact to expand the hole, but when it is pushed deeper, the air in the pilot hole becomes the pushing resistance.

[0035] Therefore, when looking at the state before impact in the case where a triangular pyramid is inserted into the lower hole and in the case where a square pyramid is inserted, the area of the equilateral triangle inscribed in the lower hole is 41% of the area of the lower hole, and the area of the square inscribed in the lower hole is 64% of the area of the lower hole. When inserting deeply, since the gap tends to become even narrower, the tip of the cross-section quadrilateral with a square pyramid shape, which originally has a smaller gap for air to escape, has a greater pushing resistance compared to the triangular pyramid with a triangular cross-section. Since the moil point tool obtains crushing force by deeply biting into the rod, if the pushing resistance is large, it becomes difficult to deeply bite in, and the crushing force is significantly attenuated.

[0036] Also, if the dust generated by crushing cannot be discharged from the lower hole, the dust itself also becomes a pushing resistance. In both the case of the triangular pyramid and the case of the square pyramid, the depth of the tip inserted is approximately the same. Therefore, the volume of the tip of the tool inserted into the lower hole is proportional to the above-mentioned area according to the volume formula of the pyramid (base area × height ÷ 3), and the inserted volume also becomes smaller. Thus, in the case of the triangular pyramid, the space below the lower hole is relatively large, so the gap is large, the dust is easily discharged, and it is difficult to become a pushing resistance. In this way, for the triangle and the square, the moil point tool with a triangular cross-section tip is significantly advantageous for discharging the crushed pieces as the difference in the size of the gap is obvious.

[0037] Compared with the present invention, in the case of the wedge point of a minus driver-shaped single-character wedge, since the tip is a single-character with the same thickness as the rod diameter, even if there is a smaller-diameter lower hole, it does not enter the lower hole, and the lower hole does not work effectively. Since it bounces back, many flying stones are generated, and it is not easy to obtain a sufficient crushing depth.

[0038] In the present invention, further, a slit (6) may be provided in the chamfered portion (3) in the axial direction from the tip direction toward the main body portion. Combining the slits makes it difficult for the internal pressure to increase and makes it easier to secure the pushing depth. In addition, since the surface area increases, it is easy to sufficiently secure the heat treatment hardening depth. For example, in the case of the rod with an outer diameter of 18 mm described above, slits (6) each having a width of 2 mm and a depth of 1 mm may be appropriately provided in the chamfered portion (3).

[0039] When the cross-section of the triangular pyramid-shaped tip of the tip portion (2) of the moil point tool (1) of the present invention is an equilateral triangle, the three chamfered portions are equal. In addition, an isosceles triangle cross-section may be used. It may be a slightly flat isosceles triangle with the base longer than the equal sides, or an isosceles triangle with the equal sides slightly longer than the base.

[0040] When a row of a large number of pilot holes (8) drilled linearly in the object (7) and the tip portion (2) of the moil point tool (1) are aligned so that one side of the equilateral triangle of the cross-section of the triangular pyramid or the base of the isosceles triangle is parallel to the row of the pilot holes and inserted into the pilot holes (8), and crushed with an impact device, cracks are likely to progress in the direction of adjacent pilot holes, or the moil point tool spreads along the angle opposing the base, so it spreads greatly in a direction perpendicular to the row of the pilot holes and breaks, so it becomes a large lump and is easy to break.

[0041] Therefore, it is preferable to crush while one of the chamfered portions of the triangular pyramid at the tip of the moil point tool (1) is in a direction parallel to the row of the pilot holes.

[0042] Next, taking the case of crushing a concrete block of a rectangular parallelepiped (width 700 mm, depth 300 mm, height 300 mm) of a test piece using the moil point tool of the present invention as an example, one form of the crushing method will be described. In this description, the side wall on the front side of this rectangular parallelepiped is defined as the front side free end, and hereinafter, taking as an example the crushing by an impact tool using the triangular pyramid-shaped moil point tool (outer diameter 18 mm) of the present invention aimed at crushing this free end side, an example of the crushing procedure will be described.

[0043] (Regarding the drilling of pilot holes) Since the outer diameter of the moil point tool is 18 mm, for drilling pilot holes of about half the size, a φ8.5 mm drill bit (SDS φ8.5 mm 3D bit) was attached to a vibration drill (GBH2-26-DE manufactured by Bosch) and used. The drilling positions of the pilot holes were set such that the distance from the front of the upper plane of the rectangular parallelepiped was 50 mm, and the pilot holes were sequentially drilled with a 50 mm interval between them. Note that the first pilot hole was located at a position 60 mm from the left side surface. When drilling a plurality of pilot holes in this way, if the pilot holes are drilled at intervals in a row, the crushing efficiency will increase. Also, a plurality of rows of pilot holes may be opened in advance.

[0044] The distance between the pilot holes is preferably about 2 to 4 times the outer diameter of the moil point tool.

[0045] (Crushing) The moil point tool is a triangular pyramid-shaped one obtained by chamfering the tip of a round bar steel material with a length of 300 mm and an outer diameter of 18 mm in three directions with an inclination of about 10 degrees. The impact tool is GBH7-46-DE manufactured by Bosch, and the shank portion shape of the moil point tool is a shape adapted to this.

[0046] The tip of the moil point tool is oriented as indicated by ▽ or △ in FIGS. 2 and 3 so that the base of the triangle (one side in the case of an equilateral triangle) is parallel to the row of perforations of the lower holes, that is, in a direction parallel to the lateral direction of the cube. The vertex opposite the base becomes a force that tries to expand in the depth direction when the moil point tool bites deeply. Since the vertices at both ends of the base are close to the direction of the adjacent lower holes, it is likely to lead to collapsing the periphery of the adjacent lower holes. By being a triangular pyramid, it bites deeper, so that the crushed pieces become larger and the crushing efficiency is increased.

[0047] For crushing along the lower holes, after applying a blow from the impact tool to one lower hole to make the moil point tool bite deeply and crush the surroundings, the procedure of moving to the adjacent lower hole, inserting the moil point tool, and applying a blow is repeated. Alternatively, the object can be crushed by sequentially proceeding with repeating the blows several times to the same lower hole and then moving to the adjacent lower hole and repeating the blows.

[0048] Regarding the rectangular parallelepiped concrete block of the above test piece, the crushing characteristics were confirmed using the moil point tool with a triangular pyramid-shaped tip according to the present invention and, as comparative examples, the moil point tool with a square pyramid-shaped tip and the single-letter wedge point tool. In the concrete block with the lower holes arranged in a row, after arranging the tip of the tool in the direction shown in FIGS. 2 to 7 with respect to the lower holes, a crushing test was performed using a hand-held impact tool.

[0049] When assuming that it is the free end of the part to be crushed that appears in front of the rectangular parallelepiped shown in FIGS. 2 to 7, a crushing test was carried out under the following conditions. Example 1: The triangular pyramid-shaped tip was inserted into the lower hole in the direction of △. Example 2: The triangular pyramid-shaped tip was inserted into the lower hole in the direction of ▽. Example 3: The triangular pyramid-shaped tip was oriented in the direction of △, and a crushing test was performed without lower holes. Comparative Example 1: The square pyramid-shaped tip was oriented in the direction of □ and inserted into the lower hole. Comparative Example 2: The square pyramid-shaped tip was oriented in the direction of ◇ and inserted into the lower hole. Comparative Example 3: A crushing test was conducted without a lower hole with the tip of the quadrangular pyramid shape facing ◇. Comparative Example 4: A one-character wedge-shaped tip was oriented in the | direction and pressed against the lower hole from above. Comparative Example 5: A one-character wedge-shaped tip was oriented in the - direction and pressed against the lower hole from above. Comparative Example 6: A crushing test was conducted without a lower hole with the tip of the one-character wedge shape facing |.

[0050] Regarding the state of crushing, the following items were evaluated on a five-point scale, and the results are shown in Table 1. · Crushing efficiency: The worst progress was rated 1, and the best was rated 5. · Size of the shape of the crushed pieces: Small pieces were rated 1, and those with large cracks were rated 5. · Amount of flying stones: When the amount of small pieces bounced off by the tool was large, it was rated 1, and when it was small, it was rated 5. · Amount of dust: When the amount of fine dust generated was large, it was rated 1, and when it was small, it was rated 5. · Progress in the depth direction: The shallower the penetration depth of the tool was rated 1, and the deeper one was rated 5. · Rebound of the tool: When the degree of the tool bouncing was large, it was rated 1, and when it did not bounce, it was rated 5. · Slipping of the tool: When the tool slipped on the surface of the object, it was rated 1, and when it did not slip, it was rated 5. · Noise: When the noise during crushing was large, it was rated 1, and when the noise was small, it was rated 5. · Vibration: When the vibration transmitted to the operator during crushing was large, it was rated 1, and when the vibration was small, it was rated 5.

[0051]

Table 1

[0052] The moil point tool of the present invention is in the shape of a triangular pyramid. When there is a lower hole as in Examples 1 and 2, the chisel can easily penetrate along the lower hole and bite deeply, so large cracks occur, the crushing efficiency is the highest, and the crushed pieces are also large. The generation amount of flying stones and dust is small, the tool rarely bounces back, and the stacking is also small. Also, the tip of the tool did not slip and the force did not deviate from the biting direction and escape. Compared with the square pyramid-shaped tool, the triangular pyramid-shaped tool was less likely to stick to the lower hole because its tip was stabbed into the lower hole. When there is a lower hole, it is the tool with the highest crushing ability and shows excellent performance compared to the conventional square pyramid-shaped moil point tool. Also, as shown in Example 3, when there is no lower hole, the tool may bounce or slip, but the tool can easily penetrate in the depth direction, and if it penetrates, medium-level rock-breaking hardening can be obtained. Even when there is no lower hole, it was the most excellent in crushing ability compared to the comparative example.

[0053] The square pyramid-shaped moil point tool of Comparative Example 1 had a parallel orientation between the free surface and the side of □, so the crushing efficiency remained at a medium level and did not lead to large-scale crushing, resulting in medium-sized crushed pieces. Although it initially crushed to enter the lower hole, the crack was difficult to progress, and the square pyramid-shaped tool sometimes stabbed into the test piece and stacked up.

[0054] The square pyramid-shaped moil point tool of Comparative Example 2 was oriented as ◇, so it was more excellent in crushing efficiency than Comparative Example 1. However, although it could initially crush to enter the lower hole, the tool was likely to be stabbed and stacked, and the work could not proceed. Compared with the triangular pyramid shape, the penetration depth became difficult to obtain halfway through, and it sometimes stacked up.

[0055] The square pyramid-shaped moil point tool of Comparative Example 3 became likely to be stabbed, stacked, and clogged when there was no lower hole. A large amount of flying stones and dust were generated, and there were also bounces and slips.

[0056] In Comparative Example 4, the wedge point has a lower hole, but since the tip of the tool cannot enter a lower hole with a small diameter, it is difficult to exert a guiding effect, the penetration depth cannot be sufficiently obtained, and the tool is likely to bounce or slip. Also, the noise and vibration increased.

[0057] In Comparative Example 5, the wedge point has a lower hole, but since the tip of the tool cannot enter a lower hole with a small diameter, it is difficult to exert a guiding effect, the penetration depth cannot be sufficiently obtained, and the tool is likely to bounce or slip. Also, the noise and vibration increased. The crushed pieces were slightly larger and more cracked than in Comparative Example 4, resulting in a slight difference in the rock-breaking property, but there was a problem in that bouncing and slipping were large and handling was difficult.

[0058] In Comparative Example 6, since there is no lower hole, it is likely to bounce and slip, and the crushing efficiency is poor. There were many flying stones, the penetration depth was shallow, and a lot of dust was generated. The vibration and noise were also large. Although a rock-breaking effect can be obtained once it bites in, the operation was difficult because slipping and bouncing were large.

[0059] As described above, the moil point tool of the present invention having a triangular pyramid-shaped tip is particularly excellent in the crushing effect when there is a lower hole, and becomes large crushed pieces to crush concrete blocks, etc., resulting in excellent workability, with less bouncing and slipping, difficult to stack, and able to penetrate the tool deeply, etc., extremely good results were obtained. Even when there is no lower hole, the workability is excellent compared to the conventional ones. It was confirmed that it is difficult to stack on hard rock formations and has excellent crushing efficiency.

Explanation of Signs

[0060] 1 Moil point tool 2 Tip part 3 Chamfered part 4 Rod main body part 5 Shank part 6 Slit 7 Object 8 Lower hole

Claims

1. A moil point tool comprising a rod-shaped tool body portion, a tip portion chamfered in a triangular pyramid shape at the tip of the tool body portion, and a shank portion at the other end of the tool body portion.

2. The moil point tool according to claim 1, wherein the cross-sectional shape of the tip portion chamfered in a triangular pyramid shape is an equilateral triangle.

3. The moil point tool according to claim 1, wherein the cross-sectional shape of the tip portion chamfered in a triangular pyramid shape is an isosceles triangle with a base longer than the equal sides.

4. The moil point tool according to claim 1, wherein the cross-sectional shape of the tip portion chamfered in a triangular pyramid shape is an isosceles triangle with a base shorter than the equal sides.

5. A method of crushing an object by the impact motion of a moil point tool having a tip portion chamfered in a triangular pyramid shape according to any one of claims 1 to 4, after drilling a number of pilot holes with a diameter of 2 / 5 to 3 / 5 of the outer diameter R of the tool body portion of the moil point tool in a row at intervals of 2 to 4 times the outer diameter R of the tool body portion on the surface of the object, comprising the steps of sequentially inserting the tip portion of the moil point tool into the pilot holes close to the end of the object and repeating the crushing operation by the impact motion to sequentially crush the object. A crushing method using a moil point tool.

6. The crushing method using the moil point tool according to claim 5, wherein the orientation of the tip of the moil point tool inserted into the pilot hole is such that one of the hypotenuses of the triangular pyramid is arranged on the end side of the object at the point of contact with the pilot hole, and the straight line connecting the contact points between the remaining two hypotenuses and the object is parallel to the row of adjacent pilot holes.

7. The crushing method using the moil point tool according to claim 5, wherein the orientation of the tip of the moil point tool inserted into the pilot hole is such that one of the hypotenuses of the triangular pyramid is arranged at the farthest point from the end side of the object at the point of contact with the pilot hole, and the straight line connecting the contact points between the remaining two hypotenuses and the object is parallel to the row of adjacent pilot holes.

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