JP4036728B2 - Self-drilling lock bolt and self-drilling lock bolt using the same - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention includes a drilling bit using the button-like chip used by being mounted to the distal end of the self drilling rock bolt, to a self drilling rock bolt fitted with this drilling bit at the tip portion.
[0002]
[Prior art]
Conventionally, a so-called button bit, in which a plurality of substantially button-shaped tips (blades) made of a cemented carbide such as tungsten carbide are implanted on the front end surface of a bit body, is a rotating rod of a rock drill or a self- It is attached to the tip of the rock bolt body as a perforated rock bolt, and is often used for excavation of ground consisting mainly of medium and hard rock layers. In such a perforated bit, most of a large number of chips are basically arranged at symmetrical positions across a line passing through the axis of the bit body, and several sets of chips are implanted so that the trajectories overlap. It is customary (see, for example, Patent Documents 1 to 3).
[0003]
[Patent Document 1]
Japanese Patent No. 3246410 (FIG. 2)
[Patent Document 2]
Japanese Patent No. 2941590 (FIG. 2)
[Patent Document 3]
Japanese Patent Publication No. 63-43551 (Fig. 2-4)
[0004]
[Problems to be solved by the invention]
The ground to be drilled varies from hard to soft, and the condition of the rock within the ground is not uniform, and often has a complex structure depending on the drilling location. For this reason, a button bit type drilling bit that can be applied to hard ground is generally used. By the way, in the case of a self-drilling lock bolt having such a drill bit at the tip, the drilling depth is about several meters at most, and the drilling diameter is only 70 to 80 mm at most. And basically, it is left in the drilling hole as it is by using it only once.
[0005]
However, all of the button bit type drill bits that have been marketed so far are designed on the assumption that they can withstand drilling holes of several hundred meters, and this is applied to self-drilling lock bolts as they are. The fact is. In other words, the conventional drilling bit is clearly over-specification in the above-mentioned use conditions such as a self-drilling lock bolt, and by using a large number of expensive cemented carbide tips, the self-drilling lock bolt as a whole It was one of the major factors for cost increase.
[0006]
The present invention has been made in view of these problems of the prior art, and as a result of intensive studies on the arrangement of chips, which occupy a large proportion of the manufacturing cost of punched bits, the present invention has been conceived. In other words, in the present invention, as few drills as possible are effective in self-drilling rock bolts in which the durability of the drilling bit itself is not required to be able to withstand drilling holes of several hundreds of meters like the above-described rock drill. By arranging them in a drilling bit for self-drilling rock bolts that realizes a significant reduction in manufacturing cost while maintaining drilling ability for a wide range of ground properties ranging from hard rock layers to soft rock layers and soft earth and sand layers, The purpose is to provide a self-drilling lock bolt using the same.
[0007]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, claim 1 of the present invention is a self-drilling lock bolt drill bit in which a plurality of substantially button-shaped chips are implanted on the front end surface of the bit body, and drilling is performed by rotation and striking force. The plurality of chips are sequentially separated from a position where each axis of the inner chip group excluding a chip located at least on the outermost peripheral side is off the axis of the bit body in the rotation direction of the drill bit. Each tip portion of the inner chip group is arranged so as to be sequentially positioned rearward in the axial direction as the bit main body is sequentially moved away from the off- axis position.
[0008]
According to this configuration, the axes of the inner chip group excluding the chips positioned at least on the outermost peripheral side are all at different distances with respect to the axis of the bit body. Different. Therefore, as the work amount of each chip increases, it is possible to drill holes with a small number of chips. Furthermore, the inner tip group sequentially moves away from the position off the axis of the bit body in the direction of rotation of the drill bit, and each tip portion of the inner chip group pivots as it sequentially moves away from the position off the axis of the bit body. Arranged so as to be sequentially positioned rearward in the center direction, that is, arranged in a “three-dimensional spiral shape” centering on the axis of the bit body (however, no chip is arranged on the axis of the bit body). Even if the number of chips is small, smooth rotation is performed, and effective drilling can be performed by the striking force.
[0009]
In addition, in the inner chip group, a step in the axial direction is formed at the tip position between adjacent chips, so when drilling in a place where a tree root exists, the roots are cut sequentially to ensure Root cutting can be done. However, the conventional button bit in which a plurality of chips are arranged on the same locus has only an effect of crushing the roots of the tree, and it is difficult to cut the roots simply by sliding the chips on the root surface.
[0010]
In the above configuration, when the plurality of chips are implanted so that the respective axes are substantially perpendicular to the front end surface , the plurality of chips are inclined outward with respect to the axis of the bit body. Since it rotates, the trajectory increases by the tilted amount, and a large amount of work can be obtained even with a small-diameter chip.
[0011]
According to a second aspect of the present invention, in the perforated bit for a self-drilling lock bolt according to the first aspect, a plurality of chips are partially overlapped with each other between adjacent chips in each trajectory caused by rotation of the perforated bit. It is arranged. In this case, the cost is slightly increased as compared with the case where the trajectories due to rotation do not overlap in all the chips, but the hole drilling ability is improved by the amount of partial overlap. Even with such an arrangement, as compared with a conventional arrangement in which several sets of a plurality of chips are arranged at positions where the same trajectory is drawn, the cost is significantly reduced.
[0012]
In the self drilling rock bolt drilling bits of each configuration, if a plurality of chips with the same diameter, drilling for chip buried to form the bit body front surface is simplified, also securing work, such as filtration cormorants with uniform As a result, the planting work can be streamlined compared to using a combination of chips of different diameters.
[0013]
The invention according to claim 3 is the self-drilling lock bolt drill bit according to claim 1 or 2, wherein the total cross-sectional area of the plurality of chips is 10 to 20% of the drilling cross-sectional area. is there. In this case, when the total cross-sectional area of the chip is less than 10%, the working efficiency particularly in excavation of the hard rock layer is drastically lowered. In addition, when it exceeds 20%, it approaches the area ratio in the conventional button bit and the durability etc. is improved by that much, but the amount of expensive carbide chips used increases, so the cost reduction effect is Decreases rapidly. For this reason, it is preferable to set in this range from the point of cost reduction effect on use conditions, such as a self-drilling lock bolt .
[0014]
According to a fourth aspect of the present invention, in the self-drilling lock bolt perforated bit according to any one of the first to third aspects, a plurality of chips are located on the outermost peripheral side. In this case, by positioning a plurality of chips on the outermost peripheral part where the work is the most burdensome and burdensome at the time of drilling, the cost reduction effect based on the above-described arrangement state of the inner chip group implanted in the inside thereof can be obtained. While maintaining, it becomes possible to cope with the enlargement of the hole diameter. That is, such a chip arrangement is suitable for drilling with a large diameter.
[0015]
Furthermore, in the self-drilling lock bolt perforated bit having the above-described configuration, if a part of the tip located on the outermost peripheral side protrudes outside the outer peripheral surface of the bit body, the side surface of the bit main body during drilling Since it becomes difficult to contact the hole wall, the drill bit can be rotated smoothly, and a drilling machine having a small capacity can be used.
[0016]
Furthermore, in the self-drilling lock bolt perforated bit having the above-described configuration, when a through-hole penetrating the wall surface is formed in the bit body, air or water supplied through the hollow portion of the lock bolt body, etc. By drilling while the pressurized fluid is ejected from the through hole, the shavings (pulverized powder) accompanying the drilling can be effectively discharged to the outside.
[0017]
According to a fifth aspect of the present invention, there is provided a self-drilling lock bolt that includes a drill bit in which a plurality of substantially button-shaped chips are planted on the front end surface of the bit body at the end, and performs drilling by rotation and striking force. The plurality of chips are sequentially separated from a position where each axis of the inner chip group excluding a chip located at least on the outermost peripheral side is off the axis of the bit body in the rotation direction of the drill bit. Each tip portion of the inner chip group is sequentially positioned rearward in the axial direction as the bit body is gradually separated from the position where the axial center is removed . According to this configuration, by applying the inexpensive drill bit according to the first to fourth aspects, the excessive quality as in the prior art is eliminated, and the cost of the entire self-drilling lock bolt can be greatly reduced. .
[0018]
DETAILED DESCRIPTION OF THE INVENTION
The self-drilling lock bolt drill bit according to the present invention has a characteristic number of chips made of a cemented carbide which is expensive in order to reduce the cost, and which does not significantly reduce the drilling ability. The arrangement state of was adopted. As a result, it has become possible to accurately cope with an over-specification depending on the application. In addition, as the shape of the substantially button-shaped carbide tip in the present invention, for example, a two-stage conical shape in which the most advanced portion is flat, hemispherical, a tapered shape in which only the most advanced portion is rounded, and the most advanced portion is made flat. There is no particular limitation on the shape, such as a pyramid shape, and the shape is appropriately selected according to usage conditions and the like.
[0019]
The diameter of carbide inserts may be of 7~14mm depending on the diameter of the perforation bits are used, typically the chip size becomes larger as the diameter increases in the price of the chip itself increases accordingly . However, the perforated bit according to the present invention can cope with a small diameter of about 7 to 9 mm and a large diameter, and has a large cost reduction effect together with a decrease in the number of chips itself. These cemented carbide chips are embedded in a mounting hole formed in the front end surface of the bit body, and are fixed by means such as press fitting or brazing.
[0020]
【Example】
Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. 1 to 3 show a first embodiment of a self-drilling lock bolt drill bit according to the present invention, which is a front view, a plan view, and a cross-sectional view, respectively. The perforated bit 1 shown in the figure has a bit body 2 cast into a bottomed cylindrical shape and six chips 3 a, 3 b, 3 c, which are substantially button-shaped and made of cemented carbide planted on the front end surface of the bit body 2. 3d, 3e, 3f.
[0021]
In the above configuration, the bit body 2 is formed with the rope screw portion 21 on the inner surface of the bit main body 2 with a half length from the opening end side to the front end surface side as is apparent from FIG. A concave portion 22 having a smaller diameter than that is provided on the distal end side of the rope screw portion 21, and two through holes 23 pass through the wall surface obliquely rearward from the concave portion 22 with respect to the axis, and are described later. The groove portion 28 is open. Further, the front end surface 24 of the bit body 2 is formed in a truncated cone shape including a slope portion 25 and a flat portion 26, and the end portion on the front end surface 24 side is a bulging portion 27 having a larger diameter than other portions. . Six arc-shaped groove portions 28 are provided at equal intervals on the outer peripheral surface of the bulging portion 27 and, as is apparent from FIG. 2, has a substantially gear-like shape in plan view.
[0022]
As apparent from FIG. 2, among the six chips, the chip 3 a is implanted at the center of the flat portion 26 formed at the center of the front end face 24, that is, at a position slightly off the axis of the bit body 2. Has been. The other chips 3 b, 3 c, 3 d, 3 e are implanted so as to be sequentially separated clockwise from the axis of the bit body 2 on the inclined surface portion 25. As a result, the position of the tip portion of each chip 3a, 3b, 3c, 3d, 3e is sequentially retreated in the direction of the rear end face of the bit body 2. In the embodiment, the five chips 3 a, 3 b, 3 c, 3 d, 3 e are arranged in a clockwise spiral shape, but this direction is the same as the rotation direction of the drill bit 1. Therefore, when the drilling bit 1 is applied to a counterclockwise drilling machine, it is necessary to arrange each chip counterclockwise. As described above, since the chips 3a, 3b, 3c, 3d, and 3e are spirally arranged in the same direction as the rotation direction of the drill bit 1, smooth rotation is performed even with a small number of chips. In addition, by forming a step in the axial direction at the tip position between adjacent chips, especially when drilling in places where tree roots are present, the roots are reliably cut and drilled. be able to.
[0023]
In the above-described embodiment, the tip 3f is implanted at the opposite position at the same distance across the shaft center with respect to the tip 3e located at the end of the spiral, that is, at the outermost periphery, and from the center except the outermost periphery. For the inner chip group consisting of four chips 3a, 3b, 3c, and 3d having different distances, there are two chips 3e and 3f that draw the same locus at the outermost peripheral position. Since such an array has a plurality of chips in the outermost peripheral part where the work is the most burdensome and burdensome at the time of drilling, the cost reduction effect based on the above-described array state of the inner chip group implanted in the inside thereof can be reduced. It is suitable for increasing the diameter of the drill bit while maintaining it. Further, the five chips 3b, 3c, 3d, 3e, 3f other than the chip 3a provided on the flat portion 26 are all implanted so that their axis centers are substantially perpendicular to the inclined surface portion 25. Yes. That is, since the tips 3b, 3c, 3d, 3e, and 3f rotate with respect to the axis of the bit body 2, the trajectory increases by the tilted amount, and even a small-diameter tip has a large work. A quantity is obtained. Since the two chips 3e and 3f located on the outermost periphery are planted in a place very close to the outer peripheral edge of the slope portion 25, they are more than the maximum diameter portion of the bulging portion 27 of the bit body 2. Slightly protrudes outward. The presence of these tips 3e and 3f makes it difficult for the bulging portion 27 of the bit body 2 to come into contact with the hole wall during drilling, so that the drill bit 1 can be smoothly rotated and cut with less ability. A perforator can be used.
[0024]
FIG. 4 is an explanatory diagram showing the locus of the chip in the above embodiment, and here, the chip 3b is shown. That is, the locus of the tip 3b is the farthest position on the outer peripheral edge side of the circle that contacts the axis center of the bit body 2 at the position closest to the axis side of the bit body 2 as shown by the dotted line with respect to the axis of the bit body 2 that is the center of rotation. Can be expressed as concentric circles that touch. As is apparent from this figure, the locus of the tip 3b is such that half of the tip 3c and a very small portion of the tip 3d overlap each other, and the hole drilling ability is improved by the overlap. Although no locus is shown, the chips other than the outermost peripheral chips 3e and 3f located on the same concentric circle are arranged so that the locus partially overlaps at least between adjacent chips. Even with such an arrangement, the cost can be greatly reduced as compared with a conventional arrangement in which several sets of a plurality of chips are arranged at positions where the same locus is drawn. Although not shown in the figure, the outermost peripheral chip does not necessarily have to be plural and may be one. Further, the locus of each chip may not be overlapped at all between adjacent chips.
[0025]
Next, FIG. 5 and FIG. 6 are different embodiments of the self-drilling lock bolt drill bit according to the present invention. The self-drilling lock bolt perforated bit 4 shown in FIG. 5 is formed by forming the front end face of the bit body 5 mostly as a flat part 51 and providing a slope part 52 around it. In this case, the four chips 6a, 6b, 6c, 6d are arranged in the flat portion 51 as a clockwise spiral so as to be separated from the axis of the bit body 5 in this order, and constitute an inner chip group. . The slope portion 52 is provided with two chips 6e and 6f as chips located on the outermost periphery as in the above-described embodiment. The self-drilling lock bolt drill bit 7 shown in FIG. 6 is basically configured in the same manner as the embodiment shown in FIGS. 1 to 4, but is intended for a drilling diameter larger than that of the embodiment, The number of chips has increased from 6 to 9. In this case, the inner chip group is composed of six chips 9a to 9f, and three chips 9g to 9i are arranged on the outermost periphery.
[0026]
In each of the above embodiments, chips having the same outer diameter are used, but it is of course possible to combine chips having different diameters. According to the present invention, when compared with a conventional button bit, a chip having the same hole diameter can be handled with a smaller tip, and a tip of about 7 to 9 mm is sufficient. Further, if the total cross-sectional area of all the chips is set to be 10 to 20% with respect to the drilling cross-sectional area, it is preferable in terms of cost reduction effect.
[0027]
Next, FIG. 7 shows one embodiment of the self-drilling lock bolt according to the present invention, and shows its use state. The self-drilling lock bolt 10 shown in the figure has a lock screw main body 11 in which a rope screw is formed over the entire length of the outer peripheral surface and a hollow portion (not shown) continuous in the longitudinal direction is provided inside, and a tip portion thereof. It consists of the drilled bit 1 of the previous embodiment mounted. The distal end portion of the lock bolt main body 11 is screwed with the rope screw portion 21 of the drill bit 1, whereby the hollow portion of the lock bolt main body 11 and the through hole 23 of the drill bit 1 communicate with each other.
[0028]
A rock drill 13 is connected to the rear end side of the self-drilling lock bolt 10 via a shank adapter 12, and the ground is drilled by its rotation and striking force. The rock drill 13 is connected to a compressor (not shown) so that pressurized air or water can be supplied to the lock bolt body 11 through the hollow portion of the shank adapter 12. These pressurized fluids pass through the hollow portion of the lock bolt main body 11 and reach the perforated bit 1, and are further ejected obliquely rearward from the through hole 23. In particular, when there is a crack or the like in the ground on the front surface, the pressurized fluid may escape from the crack. Therefore, by providing the through hole 23 on the rear side as in this embodiment, the dusting on the back surface of the drill bit 1 is performed. Can be effectively discharged. The pressurized fluid ejected from the bit body 2 can efficiently perforate the dust generated on the front end face side, and can perforate in a straight state while effectively preventing the perforation bit 1 from shaking. When the drilling is completed, the inside of the hole is washed, and then the grout material is appropriately injected using the same flow path to fill the hole, and the self-drilling lock bolt 10 is fixed. In addition, when there is no crack or the like on the front surface of the perforated bit 1, the dusting on the front surface of the perforated bit 1 can be effectively discharged by providing the through hole 23 in the front. Therefore, in the perforated bit of each of the above embodiments, the positions and the number of through holes and groove portions are not particularly limited.
[0029]
In the self-drilling lock bolt 10 of the above embodiment, a full screw bolt is applied to the lock bolt main body 11, but of course it is not limited to this, and only the end portion may be a screw shape. There is no problem. Of course, various modifications can be made within the technical idea of the present invention, such as changing the shape of the bit body, the shape of the chip, and the number of the punched bits themselves.
[0030]
【The invention's effect】
As described above, in the drill bit for drilling by rotation and impact force according to the present invention, each axis center of the inner chip group excluding the chip located at least on the outermost peripheral side is in relation to the axis center of the bit body. Since they are arranged so that they are all at different distances, the work amount of each chip increases, and it becomes possible to drill holes with a small number of chips, leading to cost reduction. Furthermore, the inner tip group sequentially moves away from the position off the axis of the bit body in the direction of rotation of the drill bit, and each tip portion of the inner chip group pivots as it sequentially moves away from the position off the axis of the bit body. By being arranged so as to be sequentially positioned rearward in the center direction, smooth rotation can be realized even with a small number of chips, and effective drilling can be performed with a striking force. In particular, in the inner chip group, a step in the axial direction is formed at the tip position between adjacent chips, so when drilling in a place where a tree root exists, the roots are cut sequentially to ensure Root cutting can be done. For this reason, it is particularly suitable for a self-drilling lock bolt having a shallow drilling depth and premised on one-time use, and greatly contributes to the cost reduction of the self-drilling lock bolt as a whole. The practical effect is extremely large.
[Brief description of the drawings]
FIG. 1 is a front view showing an example of a drill bit for a self-drilling lock bolt according to the present invention.
FIG. 2 is a plan view of the drill bit for the self-drilling lock bolt .
FIG. 3 is a longitudinal sectional view of the drill bit for the self-drilling lock bolt .
FIG. 4 is an explanatory view showing a locus of a chip in the self-drilling lock bolt drill bit.
FIG. 5 is a plan view showing another example of a drill bit for a self-drilling lock bolt according to the present invention.
FIG. 6 is a plan view showing another example of a drill bit for a self-drilling lock bolt according to the present invention.
FIG. 7 is an explanatory view showing a use state of the self-piercing lock bolt according to the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1, 4, 7 ... Perforated bit for self-drilling lock bolts , 2, 5, 8 ... Bit main body, 3a-3f, 6a-6f, 9a-9i ... Tip, 10 ... Self-drilled lock bolt, 11 ... Lock bolt main body, DESCRIPTION OF SYMBOLS 12 ... Shank adapter, 13 ... Rock drill, 23 ... Through-hole, 25, 52 ... Slope part, 26, 51 ... Flat part, 28 ... Groove part

Claims (5)

A self-drilling lock bolt drilling bit in which a plurality of substantially button-shaped tips are implanted on the front end surface of the bit body, and drilling is performed by rotation and striking force, and the plurality of tips are positioned at least on the outermost peripheral side. The inner center of the group of inner chips excluding the tip to be moved is sequentially separated from the position off the axis of the bit body toward the rotation direction of the drilling bit , and the inner side as the axis is sequentially separated from the position off the axis of the bit body. A self-drilling lock bolt drill bit, wherein each tip portion of the tip group is arranged so as to be sequentially positioned rearward in the axial direction. 2. The self-drilling rock bolt drill bit according to claim 1, wherein the plurality of chips are arranged such that a part of adjacent chips overlap each other in each locus by rotation of the drill bit. 3. The self-drilling lock bolt drill bit according to claim 1, wherein a total cross-sectional area of the plurality of chips is 10 to 20% with respect to a drilling cross-sectional area. The self-drilling lock bolt drill bit according to any one of claims 1 to 3, wherein there are a plurality of chips positioned on the outermost peripheral side. A self-drilling lock bolt that includes a drilled bit in which a plurality of substantially button-shaped chips are implanted on the front end surface of the bit body at the end, and drills holes by rotation and striking force. Each axis center of the inner chip group excluding the chip located on the outermost peripheral side is sequentially separated from the position off the axis of the bit body toward the rotation direction of the drill bit, and the position where the axis of the bit body is off A self-drilling lock bolt, wherein the tip portions of the inner chip group are sequentially positioned rearward in the axial direction as they are sequentially separated from each other.

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