Moilpoint tool and crushing method using the same

Abstract

To provide a moilpoint tool with a structure that does not easily obstruct the discharge of dust and air from the borehole being crushed, reduces the occurrence of stacking due to wear, and prevents a decrease in crushing capacity due to internal pressure or blockage of the borehole. [Solution] A moil point tool comprising a rod-shaped tool body, a tip portion of the tool body chamfered into a triangular pyramidal shape with a triangular diameter cross-section, and a shank portion at the other end of the tool body, wherein the main body portion is characterized in that at least one-third of the area of ​​the main body portion closer to the tip portion has an irregularly shaped columnar portion with a cross-sectional outer shape of three overlapping peaks.

Description

Technical Field

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[0003]

[0001] The present invention relates to a moil point tool having a triangular pyramid-shaped tip. The moil point tool is a tip tool with a pointed tip of a rod used for crushing rock, rock, concrete structures, concrete paving plates, 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 each 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 desired location of the object in advance with a drill, and 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 two directions are polished first and then the left and right two directions are polished, the polishing is easy and the processing is easy in terms of work.

[0005] Furthermore, a design has been proposed to create a slit-like narrow groove extending from the tip of the tool towards the rod body (see, for example, Patent Publication 1). The aim is to increase the surface area, thereby allowing for a deeper heat treatment depth and extending the crushing performance and lifespan. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2008-231876 [Overview of the project] [Problems that the invention aims to solve]

[0007] Crushing with impact tools involves vibrating the crushing tool back and forth, repeatedly impacting the target object to advance the crushing process. In particular, for hard objects such as rock, which are difficult to crush, a pilot hole is drilled beforehand, and the tool inserted into the pilot hole acts as a guide, penetrating deeply 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 pyramidal moil point is thrust into the pilot hole, the pyramid has many contact points and the gap with the pilot hole is small, so it effectively becomes almost completely blocked.

[0008] Consequently, when the tip of the tool bites into the object, the contact surface creates resistance. In addition, the impact of the blow compresses the air containing the small fragments and dust, making it difficult to expel them through the gap in the pilot hole. This increases the pressure inside the pilot hole, preventing the tool from biting down and reducing the crushing efficiency. Furthermore, if the crushed dust clogs the pilot hole, crushing becomes much more difficult. If the tool gets stuck, it becomes immobile and unable to be removed, stopping the crushing process. This prevents the crushing operation from being repeated, forcing an interruption in the crushing work until the tool can be removed again. Thus, when the tool gets stuck, extra effort is required to remove it.

[0009] Conventional moilpoint tools generally have a square pyramidal tip due to manufacturing and processing considerations. While this is said to provide excellent crushing power because the material splits in all directions along the ridges of the hypotenuse, it also leads to drawbacks such as increased internal pressure in the pilot hole hindering the crushing process and making it difficult to expel dust. In other words, with a square pyramidal shape, the crushed dust tends to accumulate and clog the pilot hole, hindering the progress of crushing. Furthermore, because the material splits in all directions, cracks form in a cross shape, making it difficult to control the direction of crushing. That is, the direction of crushing is influenced by the four corners of the moilpoint, causing a cross-shaped distortion, making it difficult to control the crushing direction as intended.

[0010] Creating slits in the center of each of the four faces of a square pyramid, extending from the tip towards the rear, promotes air expulsion and reduces internal pressure. However, this requires the extra step of cutting grooves to create the slits. Since the moil point tool is subjected to repeated impacts, the tip gradually wears down, and the grooves inevitably need to be re-machined each time the rod tip wears down. Thus, slitting alone is susceptible to wear and cannot be considered a sufficient and stable solution.

[0011] Therefore, one of the problems that the present invention aims to solve is to provide a crushing moil point tool that has a pointed tip that makes it easy to penetrate the target object and has excellent crushing power for hard rock, while suppressing the reduction in crushing ability due to internal pressure in the pilot hole and dust, and that allows for easier control of the direction of crushing than conventional moil point tools.

[0012] The main body of a moilpoint tool is generally cylindrical with a circular cross-section or hexagonal prism with a hexagonal cross-section. Crushers efficiently crush materials by allowing the tip of the moilpoint tool to penetrate deeply into the hole below the material to be crushed. However, due to the circular or hexagonal cross-section, the hole can easily become blocked, and the internal pressure can increase due to air and dust that cannot be expelled. This internal pressure and dust can prevent the tip of the moilpoint tool from penetrating deeply, reducing crushing efficiency. Furthermore, as the tip of the moilpoint tool wears down with repeated crushing operations, and especially as the triangular pyramidal tip of the moilpoint wears down, crushed dust becomes difficult to expel from the hole, leading to clogging and a phenomenon called stacking.

[0013] Therefore, a further problem that the present invention aims to solve is to provide a moilpoint tool with a structure that does not easily obstruct the discharge of dust and air from the hole to be crushed, reduces the occurrence of stacking due to wear, and does not easily reduce the crushing capacity due to internal pressure or blockage of the hole. [Means for solving the problem]

[0014] Therefore, after diligent research, the inventors discovered that even with a pointed tool, a cone or square pyramid shape results in large contact with the pilot hole, making it difficult to release the pressure inside the hole, thus reducing the biting force and resulting in inferior crushing power. On the other hand, when the tip of the rod (with a circular or hexagonal cross-section) is pointed into a triangular pyramid shape, there are fewer contact points with the pilot hole, and the gap with the pilot hole is large, making it easy to discharge the crushed fragments, and the rod tip is less affected even if it wears down somewhat. Furthermore, they found that a triangular cross-section makes it easier to control the crushing direction of the material being crushed compared to the tip of a square pyramid or cone.

[0015] Furthermore, we found that if the outer shape of the cross-section of the main body near the tip of the moilpoint tool is made into an irregularly shaped polygon with a contour of three overlapping peaks, that is, an irregularly shaped columnar part with a thick Y-shaped cross-section, then even when the tip of the triangular pyramid penetrates deeply or when the tip of the triangular pyramid wears down due to crushing, blockage by dust between the tip and the pilot hole during wear is less likely to occur, the gap between the tip and the pilot hole is easier to maintain, the internal pressure inside the pilot hole does not easily increase, and crushing efficiency can be maintained while the penetration remains good.

[0016] In other words, the first means for solving the problems of the present invention is a moil point tool comprising a rod-shaped tool body, a tip portion of the tool body chamfered into a triangular pyramidal shape with a triangular diameter cross-section, and a shank portion at the other end of the tool body, wherein the main body is characterized in that at least one-third of the area of ​​the main body closer to the tip portion has an irregularly shaped columnar portion with a cross-sectional outer shape of three overlapping peaks. In other words, the moil point tool comprising a rod-shaped tool body, a tip portion of the tool body chamfered into a triangular pyramidal shape with a triangular diameter cross-section, and a shank portion at the other end of the tool body, wherein the main body is characterized in that at least one-third of the area of ​​the main body closer to the tip portion has an irregularly shaped columnar portion with a cross-sectional outer shape of Y.

[0017] The steel tool, with its tip beveled in three directions to create a triangular pyramidal shape, has a sharp tip that easily bites into objects. To prevent blockage due to tip wear, the main body has a uniquely shaped columnar section with a three-peaked cross-section on the tip side, and a portion of the rectangular column on the tip side of the main body is thinned in a Y-shape to form this uniquely shaped columnar section.

[0018] The second method is a moil point tool according to the first method, characterized in that the cross-sectional shape of the tip, which is chamfered in a triangular pyramidal shape, is an equilateral triangle.

[0019] The third method is a moilpoint tool according to the first method, characterized in that the cross-sectional shape of the tip, which is chamfered in a triangular pyramidal shape, is an isosceles triangle with a base longer than equal sides.

[0020] The fourth method is a moil point tool according to the first method, characterized in that the cross-sectional shape of the tip, which is chamfered in a triangular pyramidal shape, is an isosceles triangle with a base shorter than equal sides.

[0021] Furthermore, an axial slit may be provided from the chamfered portion of the moil point tool toward the main body, and combined with a triangular pyramidal shape. Heat treatment ensures sufficient surface hardening, and also allows for better discharge of pressure and dust from within the pilot hole.

[0022] Furthermore, the fifth means is a method for crushing an object by striking motion of a moilpoint tool having a triangularly chamfered tip as described in any one of the first to fourth means, wherein a number of pilot holes with a diameter of 2 / 5 to 3 / 5 of the outer diameter R of the tool body of the moilpoint tool are drilled in a row on the surface of the object at intervals of 2 to 4 times the outer diameter R of the tool body, and the tip of the moilpoint tool is sequentially inserted into the pilot holes near the end of the object and the crushing motion by striking motion is repeated to sequentially crush the object.

[0023] Another method of crushing is a method of crushing using the moil point tool described in the fifth method, characterized in that 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 contacts the pilot hole at the end of the object, and the straight line connecting the contact points between the remaining two hypotenuses and the object is parallel to the adjacent row of pilot holes.

[0024] Other means of the crushing method are characterized in that the direction of the tip of the moyl point tool inserted into the lower hole is such that one of the hypotenuses of the triangular pyramid is arranged at the point farthest from the end side of the object in contact with the lower hole, and the straight line connecting the contact points between the remaining two hypotenuses and the object is parallel to the adjacent row of lower holes. It is a crushing method using the moyl point tool described in the fifth means.

[0025] The advantages of crushing by these other means are as follows. First, one of the vertices of the triangle formed by the contact portion of the moyl 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 made parallel to the direction of the adjacent row of lower holes. If the triangle is to bite into the lower hole, when the tool enters deeply due to the impact of the moyl 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.

[0026] Also, one of the vertices of the triangle formed by the contact portion of the moyl point tool inserted into the lower hole of the object is arranged at a position directly opposite, which is the 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 direction of the adjacent row of lower holes. If the triangle is to bite into the lower hole, when the tool enters deeply due to the impact of the moyl point tool, the distance between the vertex far from 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.

Effects of the Invention

[0027] The moil point tool of the present invention has a triangular pyramidal tip, which means that the contact points with the pilot hole are limited to only the vertex of the triangle, and a large gap is secured between the tip and the circle of the pilot hole, ensuring that air, fragments, and dust inside the pilot hole can escape. Therefore, the pressure resisting the action of the moil point tool biting into the object due to its impact does not increase easily, allowing the tip of the moil point tool to penetrate deeply into the pilot hole. In addition, since fragments and dust are easily discharged, the stacking phenomenon in which the tip of the moil point tool remains stuck in the pilot hole of the object is reduced, and the crushing operation can be continued. As a result, deep and continuous crushing is possible, resulting in a high crushing effect.

[0028] Furthermore, using a moilpoint tool with a triangular pyramidal tip allows the tool to penetrate deeper into the pilot hole than with a square pyramidal tip, making it easier to break the object into larger fragments and thus reducing dust generation. Also, since the moilpoint tool is less likely to bounce back due to the pressure inside the pilot hole, less pushing pressure is required, allowing the rod to efficiently advance deeper along the pilot hole. In addition, the amount of flying debris scattered by the moilpoint bouncing back when it does not advance properly during pushing is also reduced. Because the moilpoint advances along the pilot hole, it is less likely to slip and is easier to control. Also, unnecessary vibrations and noise are suppressed, so the impact noise is less likely to be loud.

[0029] When the tip is triangular pyramidal, the crushing efficiency tends to be higher compared to when the tip is square pyramidal. However, when the triangular pyramidal tip of the moilpoint tool penetrates deeply into the material to be crushed, or when the moilpoint tool wears down due to repeated crushing operations, if the tool body following the tip of the moilpoint tool is cylindrical or hexagonal, the crushed dust is difficult to discharge from the hole and can become clogged, or the internal pressure increases and prevents the tool from penetrating any deeper into the hole, making it prone to getting stuck. As a result, it is difficult to obtain large pieces of crushed material, and the crushing efficiency does not improve. Therefore, by making the part of the tool body near the tip a non-linear columnar shape, as in the present invention, the external shape of the cross-section is such that the gaps around the three-peaked outer contour reduce the internal pressure and allow dust to escape. This does not diminish the advantages of the triangular pyramidal shape, and the moilpoint tool can repeatedly penetrate deeply, thus maintaining stable crushing efficiency.

[0030] Furthermore, the durability of the Moil Point tool can be enhanced by surface hardening treatments such as quenching, carburizing, nitriding, and carbonitriding. The irregularly shaped columnar section of the rod body has a large surface area, making it easier to benefit from surface hardening. Although the cross-sectional area of ​​the rod body is smaller than that of a cylinder or hexagonal prism, it is resistant to impact, breakage, and abrasion, ensuring strength and durability. This shape allows for practical use while minimizing resistance to pushing. [Brief explanation of the drawing]

[0031] [Figure 1] Figure 1 shows an example of the moilpoint tool of the present invention. The figure shows a moilpoint tool in which the outer contour of the cross-section of the part near the tip of the hexagonal rod body is an irregular columnar shape with three peaks joined together, and the tip of the end is chamfered into a triangular pyramidal shape. [Figure 2]Figure 2(a) is one aspect of the AA cross-sectional view in Figure 1. This figure shows the cross-sectional shape of the irregularly shaped columnar portion near the tip of the rod body when the rod body portion near the shank of the present invention has a hexagonal cross-section. Figure 2(b) is a diagram of the "three mountains with heads together" family crest, and is a reference diagram to explain that the shape of the outer contour of the cross-section of the irregularly shaped columnar portion resembles the outline of the outer diameter of the "three mountains with heads together" design in the family crest. [Figure 3] Figure 3 shows a cross-sectional view of an irregularly shaped columnar portion as an example of another embodiment, illustrating the cross-sectional shape of the irregularly shaped columnar portion when the shank side of the rod body portion near the shank is cylindrical (circular in cross-section). [Figure 4] Figure 4 is an explanatory diagram showing the orientation in which the tip of the Moilpoint Tool of Embodiment 1 of the present invention is inserted into an object in which pilot holes have been drilled in a row. [Figure 5] Figure 5 is an explanatory diagram showing the orientation in which the tip of the Moil Point Tool of Embodiment 2 of the present invention is inserted into an object in which pilot holes have been drilled in a row. [Figure 6] Figure 6 is an explanatory diagram showing the orientation in which the tip of the square pyramidal moil point, which is Comparative Example 1, is inserted into an object that has been drilled with pilot holes in a row. [Figure 7] Figure 7 is an explanatory diagram showing the orientation in which the tip of the square pyramidal moil point, which is comparative example 2, is inserted into an object that has been drilled with pilot holes in a row. [Figure 8] Figure 8 is an explanatory diagram showing the orientation in which the tip of a straight wedge-shaped wedge point, which is Comparative Example 4, is inserted into an object that has been drilled with pilot holes in a row. [Figure 9] Figure 9 is an explanatory diagram showing the orientation in which the tip of a straight wedge-shaped wedge point, which is Comparative Example 5, is inserted into an object that has been drilled with pilot holes in a row. [Modes for carrying out the invention]

[0032] Embodiments of the Moilpoint tool of the present invention will be described with reference to the drawings as appropriate. The moil point tool (1) of the present invention shown in Figure 1 is formed in a triangular pyramidal shape with a triangular tip by sharply chamfering the tip (2) of the rod body (4) of a steel bar, and the chamfered portion (3) is removed by grinding and the surface is polished as appropriate.

[0033] For example, as an example of a moilpoint tool (1) used in a handheld impact tool, if we take a rod with an outer diameter of 18 mm and a total rod length of 300 mm as an example, the initial length of the tip (2) is 55 mm, and the chamfered parts (3) of the three chamfered sides of the triangular pyramidal shape are each inclined at approximately 10 degrees from the centerline of the rod's axis, so that the crushing force of the moilpoint tool can be concentrated at the tip of the triangular pyramidal tip (2) formed by these inclinations.

[0034] The outer diameter of the rod body (2) can be appropriately set to suit the size and type of impact tool used (from large hydraulic types to handheld types). Similarly, even if the outer diameter of the steel rod is thicker than 18 mm, a triangular pyramidal tip shape can be formed by providing a chamfered section with an inclined surface of about 10 to 15 degrees at the tip.

[0035] In the case of conventional square pyramidal moil point tools, for a rod with the same outer diameter of 18 mm and total length of 300 mm, the inclination of the four chamfered surfaces at the tip, spaced 90 degrees apart, is approximately 10 degrees from the axis centerline, and the initial length of the tip is approximately 50 mm. Therefore, the inclination of the tip of the triangular pyramid of the present invention ensures an inclination angle similar to that of conventional moil point tools, and its ability to penetrate pilot holes is equivalent to or better than that of conventional tools, with the inclination of the chamfered surfaces not hindering penetration or rock splitting at all.

[0036] Next, the rod body portion (4) adjacent to the tip portion (2) has a solid, irregularly shaped columnar portion (9) for more than one-third of its length from the tip. The cross-sectional shape (10) of the irregularly shaped columnar portion (9) is such that its outer contour resembles the three overlapping peaks of a family crest, as shown in Figure 2(a). Note that the gaps that appear between opposing peaks in the three overlapping peaks family crest shown in Figure 2(b) do not exist within the irregularly shaped columnar portion of the present invention; it is solid. In other words, the cross-section of the irregularly shaped columnar portion (9) is a thick Y shape.

[0037] The other end of the rod body (4) is equipped with a shank (5) that connects to an impact tool. The slit grooves and other features of the shank (5), such as those with a convex or concave shape to prevent rotation, can be appropriately set to suit the size and type of impact tool used (from large hydraulic types to handheld types).

[0038] The material of the moil point tool of the present invention is steel, and the same material as that used for ordinary moil point tools can be applied. Since it is prone to wear, carbon steel that is suitable for hardening treatment by heat treatment such as quenching and tempering is preferable. Furthermore, considering the heat treatability, special steels such as chromium molybdenum steel such as SCM435 and SCM440 may be used. In this way, if the surface of the moil point tool is hardened by heat treatment, it will have excellent wear resistance and can be subjected to repeated crushing treatment. The cross-sectional outer shape (10) of the irregular columnar part (9) of the rod body is a three-peaked shape with the tops joined together, so the cross-sectional area is small but the surface area is large, so it easily benefits from surface hardening by heat treatment such as quenching, carburizing, nitriding, and carbonitriding, and strength and durability can be ensured.

[0039] Conventionally, the cross-section of the steel bar in the rod body (4) was circular or hexagonal. However, in the present invention, the tip-side portion of the rod body is made into an irregularly shaped columnar section (9) with a cross-sectional shape (10) that resembles the three-peaked shape of a family crest, with the outer contour being a thinned-out section as shown in Figure 2(a) or Figure 3. This irregularly shaped columnar section (9) can be formed by cutting or forging the tip-side portion (6) of the hexagonal or cylindrical rod body (4) into a thick Y-shape, such that the outer cross-sectional shape resembles the three-peaked shape of a family crest.

[0040] For example, if the outer diameter (or diagonal length) is 18 mm, a recess with a maximum depth of approximately 6 mm is formed from the virtual outer diameter of the irregularly shaped columnar part (9) for about 100-150 mm from near the tip of the rod body toward the shank, and the thickness of the protruding part, which is like the three blades of a Y-shaped cross-section, is about 7 mm. By using this irregular cross-section, a gap is formed around the rod body, which allows pressure and dust during crushing to escape and makes it less likely for the moil point tool to penetrate deeply into the object.

[0041] The objects that this invention aims to crush are hard and difficult to crush, such as concrete structures, concrete pavements, bedrock, and rocks. Therefore, a pilot hole slightly smaller than the outer diameter of the rod is drilled to a depth of about 100 mm, and then the pointed tip of the moilpoint tool is inserted using this pilot hole as a guide. The moilpoint tool then forcefully strikes the object with its impact tool, and using the pilot hole as a guide, the moilpoint tool penetrates deeply into the concrete or bedrock, pushing outwards from the pilot hole and crushing the object with impact.

[0042] The size of the pilot hole in the object is smaller than the outer diameter of the rod of the moil point tool, and the load when drilling is also large. Therefore, the outer diameter of the pilot hole should be about 1 / 3 to 3 / 4, preferably 2 / 5 to 3 / 5, of the outer diameter of the rod, and preferably about 1 / 2 as a guideline. If the outer diameter of the pilot hole is half the size of the outer diameter of the rod, when the rod is inserted deeply, the area of ​​the pilot hole will be expanded to four times its original size, so if it can be inserted deeply, it will lead to a very large crushing force.

[0043] The amount of space around the tool differs depending on whether the tip of the moil point tool inserted into the circular pilot hole is a square pyramid or a triangular pyramid. The tip inserted into the pilot hole is pushed further in by impact, widening the hole, but the air inside the pilot hole acts as resistance to this pushing motion.

[0044] Therefore, looking at the pre-impact state when a triangular pyramid is inserted into the pilot hole and when a square pyramid is inserted, the area of ​​the equilateral triangle inscribed in the pilot hole is 41% of the area of ​​the pilot hole, and the area of ​​the square inscribed in the pilot hole is 64% of the area of ​​the pilot hole. When inserted deeply, the gap narrows further, so the square pyramidal tip with a square cross-section, which has a smaller gap for air to escape from to begin with, will have greater pushing resistance compared to the triangular pyramidal tip with a triangular cross-section. Moilpoint tools obtain crushing force by deeply inserting the rod, so if the pushing resistance is high, it becomes difficult to insert deeply, and the crushing force is greatly reduced. In the present invention, pressure can be released from the gap in the irregularly shaped columnar part (9) near the tip (6) of the main rod body at the moment of deep insertion, so the pushing resistance can be further reduced.

[0045] Furthermore, if the dust generated by crushing cannot be discharged from the hole below, the dust itself becomes a resistance to pushing. In both the case of a triangular pyramidal shape and a square pyramidal shape, the depth to which the tip is inserted is approximately the same, so the volume of the tip of the tool inserted into the hole is proportional to the area, as shown by the formula for the volume of a pyramid (base area × height ÷ 3). Therefore, in the case of a triangular pyramidal shape, the space below the hole is larger, resulting in a larger gap, which allows dust to be discharged more easily and reduces resistance to pushing. Thus, as is clear from the difference in the size of the gap between a triangle and a square, a moil point tool with a triangular cross-section and a triangular pyramidal tip is significantly advantageous for the discharge of crushed fragments. Moreover, in this invention, dust can be released from the gap in the irregularly shaped columnar part (9) near the tip (6) of the main rod the moment it is deeply inserted, so the tip is less likely to become blocked, and the efficiency does not decrease even when the crushing operation is repeated.

[0046] In contrast to the present invention, with a wedge point shaped like a flathead screwdriver, the tip is a straight line with the same thickness as the rod diameter. Therefore, even if there is a smaller diameter pilot hole, it does not enter the pilot hole, and the pilot hole is not very effective. As it bounces off, many flying stones are generated, and it becomes difficult to obtain a sufficient crushing depth.

[0047] In the present invention, additional slits (not shown) may be provided in the chamfered portion (3) in the axial direction from the tip towards the main body. Combining slits makes it easier to secure a greater indentation depth by preventing the internal pressure from rising, and also makes it easier to secure a sufficient heat treatment hardening depth by increasing the surface area. For example, in the case of the rod with an outer diameter of 18 mm as described above, slits with a width of 2 mm and a depth of 1 mm may be appropriately provided in the chamfered portion (3).

[0048] The triangular pyramidal tip of the moilpoint tool (1) of the present invention has three equally spaced chamfered edges if its cross-section is an equilateral triangle. Alternatively, it may have an isosceles triangle cross-section. It may also have a slightly flattened isosceles triangle with a base longer than the equal sides, or an isosceles triangle with a base slightly longer than the equal sides.

[0049] When a series of pilot holes (8) are drilled in a straight line into the object (7), and the tip (2) of the moilpoint tool (1) is inserted into the pilot holes (8) with one side of the equilateral triangle or the base of the isosceles triangle of the triangular pyramid cross-section aligned parallel to the series of pilot holes, and the object is then crushed with an impact device, cracks tend to propagate toward adjacent pilot holes, and the moilpoint tool expands along the corner opposite the base, causing it to expand significantly perpendicular to the series of pilot holes and break, resulting in a large, easily broken mass.

[0050] Therefore, it is preferable to crush the material with one of the chamfered triangular pyramidal parts at the tip of the moil point tool (1) oriented parallel to the row of pilot holes.

[0051] Next, we will describe one form of crushing method, using the example of crushing a rectangular concrete block (700 mm wide, 300 mm deep, 300 mm high) as the target object using the moil point tool of the present invention. In this description, the side wall on the front side of this rectangular block is defined as the front free end, and below, we will describe an example of the crushing procedure using an impact tool with the triangular pyramidal moil point tool (outer diameter 18 mm) of the present invention, which is intended to crush this free end side.

[0052] (Regarding drilling the pilot hole) Since the outer diameter of the moil point tool is 18 mm, a φ8.5 mm drill bit (SDSφ8.5 mm 3D bit) was attached to a rotary hammer drill (Bosch GBH2-26-DE) to drill pilot holes approximately half the size of the tool. The pilot holes were drilled sequentially at a distance of 50 mm from the front of the top surface of the rectangular prism, with a spacing of 50 mm between each hole. The first pilot hole was drilled at a position 60 mm from the left side. When drilling multiple pilot holes in this manner, drilling them in a line with spacing between them increases the crushing efficiency. Alternatively, multiple rows of pilot holes may be drilled in advance.

[0053] The spacing between pilot holes should be approximately 2 to 4 times the outer diameter of the moil point tool.

[0054] (Crushing) The Moilpoint tool is made from a 300mm long, 18mm outer diameter round steel bar, with the tip beveled in three directions at approximately a 10-degree angle to create a triangular pyramidal shape. The impact tool is a Bosch GBH7-46-DE, and the shank shape of the Moilpoint tool is designed to match it.

[0055] The tip of the moilpoint tool is oriented so that the base of the triangle (one side if it is an equilateral triangle) is parallel to the row of drilled pilot holes, i.e., parallel to the horizontal direction of the cube, as indicated by the ▽ or △ symbols. The vertex opposite the base exerts a force that tries to expand in the depth direction when the moilpoint tool penetrates deeply. The vertices at both ends of the base are close to the direction of adjacent pilot holes, so this tends to lead to the collapse of the area around the adjacent pilot hole. Because it is a triangular pyramid, it penetrates deeper, resulting in larger fragments and increased crushing efficiency.

[0056] Crushing along a pilot hole involves applying impact from an impact tool to one pilot hole to deeply insert the moil point tool and crush the surrounding area, then moving to the next pilot hole, inserting the moil point tool, and applying impact, repeating this process. Alternatively, the target material can be crushed by repeatedly applying impact to the same pilot hole, then moving to the next pilot hole and repeating the impact process sequentially.

[0057] (Regarding differences in the shape of the tip) The crushing characteristics of the rectangular concrete blocks described above were confirmed using a moil point tool with a triangular pyramidal tip, and, as a comparative example, a moil point tool with a square pyramidal tip and a straight wedge point tool. For concrete blocks with a row of pre-drilled holes, the tool tips were positioned relative to the pre-drilled holes in the orientations shown in Figures 4 to 9, and then crushing tests were performed using hand-operated impact tools.

[0058] Assuming that the front of the rectangular prism shown in Figures 4-9 is the free end of the part to be crushed, the crushing test was conducted under the following conditions. Tip example 1: The triangular pyramidal tip was inserted into the pilot hole in a △ orientation. Tip example 2: The triangular pyramidal tip was inserted into the pilot hole in the direction of a triangle (▽). Tip example 3: The triangular pyramidal tip was oriented in a triangle shape, and a crushing test was performed without pre-drilling. Comparative Example 1: The square pyramidal tip was oriented in the direction of a square (□) and inserted into the pilot hole. Comparative Example 2: The square pyramidal tip was oriented in a diamond shape and inserted into the pilot hole. Comparative Example 3: The tip of the square pyramidal shape was oriented in a diamond shape, and a crushing test was performed without pre-drilling. Comparative Example 4: The wedge-shaped tip was oriented in the direction of | and pressed against the pilot hole from above. Comparative Example 5: The wedge-shaped tip was oriented in the direction of a "-" and pressed against the pilot hole from above. Comparative Example 6: The wedge-shaped tip was oriented in the | direction, and a crushing test was performed without pre-drilling. Example 1: A triangular pyramidal tip with an irregularly shaped columnar section was inserted into the pilot hole in a △ orientation. Example 2: A triangular pyramidal tip with an irregularly shaped columnar section was inserted into the pilot hole in the direction of a triangle (▽). Example 3: A triangular pyramidal tip with an irregularly shaped columnar section was oriented in a △ direction, and a crushing test was performed without pre-drilling.

[0059] The crushing process was evaluated on a 5-point scale for each of the following items, and the results are shown in Table 1. • Crushing efficiency: The worst progress was assigned a score of 1, and the best progress was assigned a score of 5. • Size of the fragments: Small fragments were assigned a value of 1, and larger pieces were assigned a value of 5. • Amount of flying debris: A value of 1 was assigned when the tool knocked out a large amount of small debris, and a value of 5 when it knocked out a small amount. • Amount of dust: A value of 1 was used when the amount of fine dust generated was large, and a value of 5 when it was small. • Progression in the depth direction: A shallow tool penetration depth was assigned a value of 1, and a deeper penetration depth was assigned a value of 5. • Tool bounce: A score of 1 indicates a high degree of tool bounce, while a score of 5 indicates no bounce. • Tool slippage: A score of 1 indicates that the tool slips on the surface of the object, while a score of 5 indicates that it does not slip. • Noise: The noise level during crushing was rated from 1 (high) to 5 (low). • Vibration: The vibration transmitted to the worker during crushing was rated as 1 for high vibration and 5 for low vibration.

[0060] [Table 1]

[0061] From the above results, it was confirmed that a triangular pyramidal shape is superior for the tip. Therefore, as a further embodiment of the present invention, we evaluated Examples 1 to 3 using a Moil Point tool in which the tip is triangular pyramidal and the rod body is an irregularly shaped columnar part (9), and the following improvements were also made to the tip of the triangular pyramidal shape.

[0062] [Table 2]

[0063] In the tip example 1, where the tip is a triangular pyramidal shape, when the moil point tool of the present invention is equipped with an irregularly shaped columnar portion (9) of the rod body, a crushing test was conducted and the evaluation score for the amount of flying stones improved from 4 to 5.

[0064] Furthermore, in a crushing test where the arrangement of the triangular pyramids was in the orientation of tip example 2, the moil point tool equipped with the irregularly shaped columnar portion (9) of the rod body of the present invention showed an improvement in the evaluation score for the amount of dust from 4 to 5, and an improvement in the evaluation score for progression in the depth direction from 4 to 5.

[0065] The moil point tool of the present invention is triangular pyramidal in shape. When there is a pre-drilled hole, as in Examples 1 and 2 of the tip, the chisel easily penetrates along the pre-drilled hole and bites deeply, resulting in large cracks, the highest crushing efficiency, and larger fragments. There is also less generation of flying stones and dust, less tool bounce-back, and less sticking. Furthermore, the tool tip does not slip, preventing the force from diverting from the direction of penetration. Compared to a square pyramidal tool, the triangular pyramidal tool is less likely to get stuck as its tip penetrates the pre-drilled hole. When there is a pre-drilled hole, it is the tool with the highest crushing capacity and shows superior performance compared to conventional square pyramidal moil point tools.

[0066] Furthermore, in an embodiment of the present invention, a moil point tool with an irregularly shaped columnar section (9) directly below the tip of the triangular pyramid is provided, which allows for smoother progress in the depth direction and is more likely to result in larger fractures, thus further improving the amount of flying stones and dust.

[0067] Furthermore, as shown in tip example 3, in the absence of a pilot hole, the tool may bounce or slip, but it penetrates easily in the depth direction, and once penetrated, moderate rock hardening is achieved afterward. Even without a pilot hole, the triangular pyramid showed the best crushing ability compared to the comparative examples. In the absence of a pilot hole, progress in the depth direction is difficult, but the amount of dust discharge is slightly improved, so the crushing efficiency is slightly improved when crushing is repeated.

[0068] In Comparative Example 1, the square pyramidal moilpoint tool had a moderate crushing efficiency because the free surface and the sides of the square were parallel. This did not lead to large fragments, resulting in only moderately fragmented pieces. Although it initially crushed the material by penetrating the pilot hole, the crack did not progress easily, and the square pyramidal tool sometimes became stuck in the test specimen.

[0069] The square pyramidal moil point tool in Comparative Example 2, oriented like a diamond, had superior crushing efficiency compared to Comparative Example 1. However, because it entered the pilot hole, although it could crush initially, the tool tended to get stuck and jammed, slowing down the work. Compared to the triangular pyramidal shape, it was difficult to achieve sufficient penetration depth midway through, sometimes resulting in jamming.

[0070] The square pyramidal moil point tool in Comparative Example 3 was prone to piercing and getting stuck and clogged when there was no pre-drilled hole. It also generated a lot of flying debris and dust, and there was rebound and slippage.

[0071] In Comparative Example 4, even with a pilot hole, the wedge point did not allow the tool tip to enter a small-diameter pilot hole, making it difficult to achieve a guiding effect. As a result, sufficient penetration depth could not be obtained, and the tool became prone to bouncing or slipping. In addition, noise and vibration increased.

[0072] In Comparative Example 5, even with a pilot hole, the wedge point did not allow the tool tip to penetrate the small diameter hole, making it difficult to achieve a guiding effect. As a result, sufficient penetration depth could not be obtained, and the tool was prone to bouncing and slipping. Noise and vibration were also increased. The fragments were slightly larger than in Comparative Example 4, resulting in a slight difference in stone-breaking ability, but the bouncing and slipping were significant, making it difficult to handle.

[0073] The wedge point in Comparative Example 6 lacked a pre-drilled hole, resulting in poor crushing efficiency due to its tendency to bounce and slip. It also produced many flying stones, shallow penetration depth, and significant dust generation. Vibration and noise were also considerable. While it achieved a rock-splitting effect once embedded, its slipperiness and bouncing made operation difficult.

[0074] As described above, the moil point tool of the present invention, equipped with a triangular pyramidal tip, exhibits particularly excellent crushing effect when a pilot hole is present, yielding extremely good results such as the crushing of concrete blocks into large fragments. Furthermore, when the triangular pyramidal tip and the irregularly shaped columnar part of the rod body are combined as in the present invention, dust discharge is excellent, and the pushback pressure can be relieved, making it easier to advance in the depth direction and less prone to getting stuck, resulting in stable and continuous crushing efficiency during the crushing operation. [Explanation of Symbols]

[0075] 1. Moilpoint Tool 2 Tip 3. Chamfered section 4. Rod body 5 Shank section 6. Near the tip of the main body of the rod 7. Object 8. Pilot hole 9 Irregular columnar part 10 Cross-sectional shape

Claims

1. A moil point tool comprising a rod-shaped tool body, a tip portion of the tool body chamfered into a triangular pyramidal shape with a triangular diameter cross-section, and a shank portion at the other end of the tool body, wherein the tool body is further characterized in that at least one-third of the area of ​​the tool body closer to the tip portion is an irregularly shaped columnar portion having a cross-sectional outer shape of three overlapping peaks.

2. A moil point tool comprising a rod-shaped tool body, a tip portion of the tool body chamfered into a triangular pyramidal shape with a triangular diameter cross-section, and a shank portion at the other end of the tool body, wherein at least one-third of the area of ​​the main body closer to the tip portion is a Y-shaped irregular columnar portion.

3. The moil point tool according to claim 1 or 2, characterized in that the cross-sectional shape of the tip, which is beveled in a triangular pyramidal shape, is an equilateral triangle.

4. The moil point tool according to claim 1 or 2, characterized in that the cross-sectional shape of the tip, which is beveled in a triangular pyramidal shape, is an isosceles triangle in which the base is longer than the equal sides.

5. The moil point tool according to claim 1 or 2, characterized in that the cross-sectional shape of the tip, which is beveled in a triangular pyramidal shape, is an isosceles triangle with a base shorter than equal sides.

6. A method for crushing an object by striking a moilpoint tool having a triangularly chamfered tip as described in claim 1 or 2, After drilling numerous pilot holes in a row on the surface of the object, with a diameter of 2 / 5 to 3 / 5 of the outer diameter R of the tool body of the Moil Point tool, spaced apart at intervals of 2 to 4 times the outer diameter R of the tool body, The procedure involves sequentially inserting the tip of the moil point tool into pilot holes near the ends of the object and repeatedly performing a crushing motion through striking, thereby progressively crushing the object. A crushing method using a moilpoint tool.

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