JP3924679B2 - Drilling bit - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an improvement of an excavation bit such as an earth auger that is fixed to the tip of a rotary excavation body.
[0002]
[Prior art]
As is well known, many excavation bits are attached to the tip of a spiral blade attached to the drive shaft of a self-propelled excavator such as an earth auger for excavating the ground. The ground is excavated by a number of bits by rotating the blades. The earth and sand by excavation is discharged to the upper part through the inside of the cylindrical head by the rotation of the spiral blade.
[0003]
Conventional bits are broadly classified into general earth and sand, flat bits for ground, and conical bits such as conical, and are used properly according to the type of ground used. As shown in FIGS. 6, 7 </ b> A, and 7 </ b> B, the flat bit 303 has a flat tip 301 fixed to the tip of the shank 302 and is fixed to the tip of the spiral blade 304.
[0004]
In such a conventional bit, the tip fixed to the tip of the shank 302 is made of a high-hardness material having excellent wear resistance against earth and sand, such as a tungsten-based cemented carbide, and is attached to the tip mounting portion of the shank 302. Installed by brazing.
[0005]
[Problems to be solved by the invention]
However, when the ground is excavated, the soil layer in which clayey soil is tightly solid is excavated in a normal flat bit 303 as shown in FIG. 6 and FIG. The soil called the soil carrier layer is a hard solid of ground clay, and in the case of a flat blade edge as shown in the figure, the blade edge does not enter the ground and has a problem that it is difficult to excavate.
[0006]
Therefore, a conical bit such as a conical is often used because it is difficult to excavate the soil layer with a normal flat bit.
[0007]
Such a soil-bearing layer can be excavated with a head equipped with a conical bit, but when the soil-bearing layer is excavated and moved to a normal ground with some rocks, the chip is missing. Since there is a problem that the head for ordinary ground is necessary, two types of heads must be prepared, and the work of handling the head is troublesome and the efficiency of excavation work is reduced. It was.
[0008]
Furthermore, since the conical bit has a small tip and low brazing strength, the weight acting on the head itself is limited, and when a large weight of the excavating machine acts, the tip may be detached even if it is placed on the ground, There was a problem that the excavation work period was prolonged due to the time required for exchanging the chips.
[0009]
On the other hand, with the sword-shaped bit, the blade edge is sharp, so it can enter the soil layer, but compared to the flat bit 303, it can not scoop up soil, and in reality it is Not suitable for drilling.
[0010]
[Problems to be solved by the invention]
Accordingly, the object of the present invention is to enable excavation work without exchanging the head even if there is a change in the ground layer during excavation, thereby improving the excavation work efficiency and shortening the excavation work period. The purpose is to provide a bit.
[0011]
[Means for solving the problems]
In order to achieve the above object, the present invention has the following technical means. In other words, using the reference numerals used in the accompanying drawings corresponding to the embodiments of the present invention, it is fixed to the excavator rotating body in the excavator and brazed to the shank 2 and the concave groove formed at the tip of the shank 2 by brazing. The tip 4 is composed of a fixed tip 4, and the tip 4 has a first cutting edge 4 </ b> A whose upper edge is inclined toward the tip from one side surface 2 </ b> A of the shank 2 in plan view, and the other side surface in plan view. A second edge 4B having an upper ridge line inclined from 2B toward the tip as a cutting edge is formed in a pointed shape, and a ridge line having a predetermined length extending vertically downward from the top surface of the tip 4 of the tip is formed at the third cutting edge 4C. And a lower ridge line 4D inclined inwardly at the lower end of the third cutting edge 4C, and a ridge line having a ridge line continuous with the ridge line of the first cutting edge 4A at the rear end of the first cutting edge 4A. For wear prevention -Up 6 In continuously provided to the drilling bit 1 Ru formed in a range of inclination ridge of the shank 2 the upper, the chip 4 is a plan view of the first cutting edge 4A and the second cutting edge 4B are cross tip parts is formed by a 61 ° 62 ° sharp angle beta, and inward in the third range angle α of the lower ridge line 4D is against the perpendicular line of 50 degrees from 25 degrees which is formed in the cutting edge 4C lower is formed so as to be inclined, in a range of 30mm from the parallel thickness B is 12mm for the plan view the first cutting edge 4A, the vertical length C of the third cutting edge 4C ridges, from 4mm to upper and lower surfaces of the chip 4 The excavation bit is formed in a range of ½ of the vertical height W of the first excavator and is fixed to the tip of the excavation rotating body so that the inclined side surface of the first cutting edge 4A faces the upper surface in the excavation direction. It is.
According to the above, when excavating a hard ground or rock with an excavator such as an earth auger, the inclined side surface of the first cutting edge 4A is fixed to the excavation rotating body (for example, the tip of the spiral blade) so as to face the upper surface in the excavation direction. The excavation bit 1 is driven to rotate. When the excavation by the excavating bit 1 is started, a strong load is intermittently or continuously applied to the tip 4 fixed to the tip of the shank 2, and at the same time, a large cutting resistance is also applied to the ridge line direction of the tip 4. .
Therefore, by configuring the tip 4 as described above, the tip of the excavation bit 1 is formed in a pointed shape, so even a hard soil layer can enter the ground, and the inclination of the first cutting edge 4A Since the side of the excavation rotating body (for example, spiral blade) is fixed so that the side faces the upper surface in the excavation direction, the excavated earth and sand can be scraped out. In addition, even if a large cutting resistance occurs due to changes in the ground layer, etc., the strength of the tip 4 can be maintained, and the occurrence of defects during excavation can be suppressed, so that excavation work can be performed without exchanging the head. As a result, the excavation work efficiency can be improved and the excavation work period can be shortened.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 is a plan view showing an excavation bit according to the present invention, FIG. 2 is a side view of the excavation bit, FIG. 3A is a plan view of a chip fixed to the tip of a shank, and FIG. 4A is a plan view of a tip in which a tip for preventing ridge wear is connected to the rear end of the first blade edge, and FIG. 4B is a plan view of the tip of FIG. 5 (A) is a front view showing a state in which the excavation bit is fixed to the tip of the spiral blade, and (B) is a side view thereof.
[0013]
In FIG. 1 to FIG. 3, reference numeral 1 denotes an excavation bit according to the present invention. The excavation bit 1 is a spiral blade attached to a drive shaft of a self-propelled excavator such as an earth auger (not shown). A plurality of pieces are mounted side by side by welding or the like, and a bit excavates the ground by the rotation of the spiral blade, and a hole equal to the diameter of the spiral blade is excavated. The earth and sand by excavation is discharged to the upper part through the inside of the cylindrical head by the rotation of the spiral blade.
[0014]
As shown in FIGS. 1 and 2, the excavation bit 1 of the present invention comprises a shank 2, a tip 4 fixed to the tip of the shank 2, and a tip 6 for preventing ridge wear. It is made of a tungsten-based cemented carbide and is fixed by brazing to a concave square groove formed at the tip of the shank 2 made of soft iron or structural alloy steel.
[0015]
Here, the shape of the tip 4 in the excavation bit 1 of the present invention is such that, in this embodiment, the tip of the cutting edge is one side surface 2A of the shank 2 in plan view, as shown in FIGS. 4A and 4B. The first cutting edge 4A having a blade edge with an upper ridge line inclined at an angle θ = 35 ° from the tip to the tip, and the second cutting edge 4B having a blade edge with an upper ridge line inclined from the other side surface 2B toward the tip in plan view The crossing angle β is in the range of 61 ° to 62 °. In this embodiment, β = 61 ° 42 ′ is formed in a tip shape, and the tip portion has a predetermined length extending vertically downward from the upper surface of the tip 4. A ridge line is formed as the third cutting edge 4C, and a lower ridge line 4D is formed at the lower end of the third cutting edge 4C. The lower ridge line 4D is inclined inward at an angle α = 35 ° 37 ′ with respect to the vertical line. The ridge line of the first cutting edge 4A The length along A is 40 mm and the thickness parallel to the first cutting edge 4A is = 20 mm, the vertical height of the vertical length of the third cutting edge 4C ridge until the upper and lower surfaces of the C = 10 mm, and the chip 4 are formed by W = 50 mm.
[0016]
Next, in the excavation bit 1 configured as described above, the inclined side surface of the first cutting edge 4A inclined at an angle θ = 35 ° from one side surface 2A of the plan view shank 2 toward the tip is shown in FIG. It is fixed to the tip of the spiral blade 10 so as to face the upper surface in the excavation direction shown in A) and (B).
[0017]
Next, a comparative example at the time of excavation with respect to the shape of the tip used for the excavation bit will be described with reference to FIGS.
[0018]
Comparative Example 1;
When the angle α <25 ° with respect to the vertical line of the lower ridge line 4D, the bit bite into the soil carrier layer was poor, and excavation resistance increased, so excavation was not possible. In addition, when α> 50 °, the cutting edge strength was weak, and the chip 4 was lost even in the case of a small gravel when excavating the normal ground. Accordingly, the angle of the lower ridgeline 4D with respect to the perpendicular is 25 ° <α <50 ° as an optimum angle for excavation.
[0019]
Comparative Example 2;
When the angle of the lower ridge line 4D with respect to the vertical line is α = 25 ° and the parallel thickness with respect to the first cutting edge 4A is B <12 mm, the strength of the chip 4 itself is insufficient and chipping of the chip occurs. Further, in the case of B> 30 mm, there is a possibility that the chip 4 may crack due to silver brazing strain, and even when no crack is generated, the chip 4 is lost during excavation due to residual strain. Accordingly, the thickness B parallel to the first cutting edge 4A is 12 mm <B <30 mm as the optimum thickness for excavation.
[0020]
On the other hand, when α = 50 ° and B <18 mm, the strength of the chip 4 itself was insufficient and the chip 4 was lost. Further, in the case of B> 30 mm, there is a possibility that the chip 4 may crack due to silver brazing strain, and even when no crack is generated, the chip 4 is lost during excavation due to residual strain. Accordingly, the thickness B parallel to the first cutting edge 4A is 18 mm <B <30 mm, which is the optimum thickness for excavation.
[0021]
Comparative Example 3;
When the vertical length C of the third cutting edge 4C extending vertically downward from the top surface of the tip 4 of the tip 4 is 4 mm> C, the cutting edge was lost even with a small gravel when excavating the normal ground. In addition, when the vertical length C with respect to the vertical height W / 2 to the upper and lower surfaces of the chip 4 is W / 2 <C, the excavation resistance acting on the blade edge during excavation of the soil carrier layer is large, and excavation becomes difficult. It was. Therefore, the vertical length C of the third cutting edge 4C is 4mm <C <W / 2, which is the optimum vertical length for excavation.
[0022]
A plurality of excavation bits 1 using the tip 4 formed in the range of dimensions and shapes as described above are attached to the tip of a spiral blade 10 (see FIG. 5) of an excavator such as an earth auger by welding or the like. When the excavation is started by rotating the plurality of excavating bits 1 together with the spiral blades, a strong load is intermittently or continuously applied to the tip 4 fixed to the tip of the shank 2, and at the same time, the ridgeline of the tip 4 A large cutting force also acts on the direction.
[0023]
Therefore, in the excavation bit 1 using the tip 4 having the above-described shape, the shape of the tip edge of the plan view tip 4 is formed at a sharply sharp angle β where the first blade edge 4A and the second blade edge 4B intersect. Therefore, it can cope with the soil layer sufficiently.
[0024]
Furthermore, since the tip 4 has a mass larger than that of a conical conical bit and has sufficient brazing strength, even if it becomes a normal ground layer due to changes in the ground layer during the excavation process, the chip 4 has some gravel. Therefore, excavation work can be continued using the same chip 4 as it is without changing the head, excavation work efficiency is improved, and the excavation work period can be shortened.
[0025]
Further, as compared with the tip of the sword tip, the spiral blade 10 has an inclined side surface of the first cutting edge 4A inclined at an angle θ = 35 ° from one side surface 2A of the shank 2 in plan view toward the tip thereof so as to face the upper surface in the excavation direction. Since it is fixed to the tip, not only can a hard soil layer enter the ground, but the excavated soil can be scraped out.
[0026]
Next, FIGS. 1, 2, and 4 show a ridge wear prevention tip 6, and this ridge wear prevention tip 6 is an inclined ridge line along the ridge line of the first cutting edge 4 </ b> A above the shank 2. In a range, it is connected to the rear end of the first cutting edge 4A and fixed by brazing, and is inserted into a concave groove having a square cross section formed along the inclined ridgeline and fixed by brazing.
[0027]
The shank 2 of the excavating bit 1 is welded to the periphery of the fixed portion of the tip 4 excluding the tip 4 and the tip 6 for preventing ridge wear or the outer peripheral surfaces (XX marked portions) 8A and 8B of the shank 2. Is hardened.
[0028]
Therefore, when excavating hard ground or rock with an excavator such as an earth auger, the cutting surface of the tip 4 fixed to the tip of the shank 2 or the ridge wear prevention tip 6 arranged adjacent to the tip 4 is continuous. A large excavation resistance acts on the ridgeline.
[0029]
Therefore, according to the excavation bit of the present invention configured as described above, the wear of the shank portion ridge line generated by a large cutting resistance acting on the ridge line extension line of the first cutting edge 4A of the tip 4 is caused by the first cutting edge. This can be prevented by the ridge wear prevention tip 6 that is continuous with the 4A ridge line.
[0030]
Further, since the shank 2 is hardened around the fixed portion of the chip 4 except the chip 4 or its outer peripheral surface, it is strong against the peripheral portion of the chip fixed portion or its outer peripheral surface (xx mark portions) 8A and 8B. Even when a load or friction is applied, wear can be avoided by the brazed portion that is hardened.
[0031]
Also, since the brazing area of the excavating bit 1 is about 10 times larger than that of the conical bit, the brazing will not be disengaged even if the weight of the excavating machine acts on the head, and the head is handled in the work. Becomes easier.
[0032]
【The invention's effect】
As described in detail above, the present invention has the following effects.
[0033]
That is, according to claim 1, since the angle of the pointed end portion where the first blade edge and the second blade edge intersect with each other in plan view of the excavation bit is formed at a sharply sharp angle in the range of 61 degrees to 62 degrees , Even a hard soil layer can enter the ground, and since the inclined side surface of the first cutting edge faces the upper surface in the excavation direction, it is fixed to the tip of the excavation rotating body (for example, spiral blade). It can be scooped out. In addition, even if a large cutting resistance is generated on the chip due to changes in the ground layer during excavation of hard ground or rock, its strength is maintained and the occurrence of defects during excavation can be suppressed, The excavation work can be continued without changing the head, and the excavation work efficiency can be improved and the excavation work period can be shortened.
[Brief description of the drawings]
FIG. 1 is a plan view showing an excavation bit according to an embodiment of the present invention.
FIG. 2 is a side view of the excavation bit.
3A is a plan view of a chip fixed to the tip of a shank, and FIG. 3B is a view taken in the direction of arrow X in FIG.
4A is a plan view of a tip in which a tip for preventing ridge wear is connected to the rear end of the first cutting edge, and FIG. 4B is a view taken in the direction of arrow Y in FIG.
5A is a front view showing a state in which an excavation bit is fixed to the tip of a spiral blade, and FIG. 5B is a side view thereof.
FIG. 6 is a front view of a spiral blade showing a state in which a conventional flat bit is fixed to the tip.
7A is a front view showing a state in which a conventional flat bit is fixed to the tip of a spiral blade, and FIG. 7B is a side view thereof.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Drilling bit 2 Shank 2A, 2B Shank side surface 4 Tip 4A 1st blade edge 4B 2nd blade edge 4C 3rd blade edge 4D Lower ridge line 6 Edge wear prevention insert 8A, 8B Brazing part 10 Spiral blade α Angle θ Inclination angle B of the first cutting edge with respect to one side surface of the shank in plan view Parallel thickness C of the tip with respect to the first cutting edge C Vertical length W of the third cutting edge W Vertical height to the top and bottom surfaces of the chip

Claims (1)

The tip 4 includes a shank 2 and a tip 4 that is fixed by brazing to a groove formed at the tip of the shank 2. The tip 4 has a tip of the shank 2 in plan view. A first cutting edge 4A having an upper ridge line inclined from one side surface 2A toward the tip as a cutting edge, and a second cutting edge 4B having an upper ridge line inclined from the other side surface 2B toward the tip in plan view as a cutting edge. And a ridge line having a predetermined length extending vertically downward from the upper surface of the tip 4 of the tip is formed as a third cutting edge 4C, and a lower ridge line 4D inclined inward is formed at the lower end of the third cutting edge 4C. is formed, above the rear end of the first cutting edge 4A, Ru formed ridge antiwear chip 6 having a ridge that is continuous with the edge line of the first cutting edge 4A is continuously provided in a range of inclination ridge of the shank 2 upper Drilling bit 1 In and,
The tip 4 is formed with a sharp pointed angle in which the angle β at which the first blade edge 4A and the second blade edge 4B intersect each other in plan view is in the range of 61 degrees to 62 degrees, and the third blade edge 4C. lower ridge 4D formed at the lower end is formed at an angle α inclined inwardly in the range of 50 degrees from 25 degrees to the perpendicular, in a range of 30mm from the parallel thickness B is 12mm for the plan view the first cutting edge 4A The vertical length C of the ridgeline of the third cutting edge 4C is formed in a range of 1/2 of the vertical height W from 4 mm to the upper and lower surfaces of the chip 4, and the inclined side surface of the first cutting edge 4A is excavated. An excavation bit characterized by being fixed to the tip of the excavation rotating body so as to face the upper surface in the direction.

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