MULTI-SHAFT EXCAVATING DEVICE

Abstract

 A reliable multi-shaft excavating device for forming a linear continuous wall unit comprises three mixing shafts (5A, 5B, 5C) for use in forming in the ground a continuous wall, and a housing (11) for maintaining intervals between said mixing shafts (5A, 5B, 5C) provided therein with first transfer means (14) rotated by the middle mixing shaft (5B), second transfer means (15) in engagement with said first transfer means (14), third transfer means (18) that is integral with said first transfer means (14), fourth transfer means (21) in mesh engagement with said third transfer means (18) and secured to a rotating shaft (19) perpendicular to a straight line connecting the centers of said mixing shafts, and sideward expanded cone-shape cutters (22) securely provided on the ends of said rotating shaft (19). According to the present invention, all the triangular projecting portions that have been left uncut are cut by cutters, and it is possible to form in the ground a continuous wall unit having semi-circular ends and linear sides. Here, since the above mentioned cutters are in a cone shape such as a frustoconical shape, even if the distances between the mixing shafts are long, most of the triangular projecting portions (portions that have not been excavated) can be excavated, and portions left uncut disintegrate naturally by their self weights, vibrations, and others. In other words, according to the present invention, it is possible to make longer portions between the mixing shafts. In addition, it is possible to reduce time and labor to be spent for forming a continuous wall unit by making longer portions between the mixing shafts.

Description

Field of the Invention

[0001] The present invention relates to a multi-shaft drilling unit comprising three rotating shafts to develop a continuous wall under the ground.

Description of the Prior Art

[0002] A soil mixing method has been widely executed as an effective technology. In a prior soil mixing method, subsoil is drilled in a wall-shape to discharge mixed liquid of cement and the like from an end point of an auger shaft in order to mix the in-situ soil to develop a continuous wall and that is applied to form cut-off walls in works on retaining the wall and shoring in underground works of civil engineering construction.

[0003] A multi-shaft auger auger machine for developing such a continuous wall is explained with reference to Figs. 5 and 6.

[0004] In these drawings, a drive unit (3) is equipped to move vertically on a guide post (2) mounted on a crawler truck (1); a multi-shaft unit (4) is connected to the lower part of said drive unit (3); and a plurality of auger shafts (three shafts as shown in the illustrated example) (5A, 5B and 5C - hereinafter referred to as just "5" collectively) are installed on said multi-shaft unit (4).

[0005] A drilling cutter (6) is equipped at the lower end of each auger shaft (5); a screw type movable wing (7), a diameter of which wing is the same as the drilling cutter (6), and a bar-shaped auger wing (8) are alternately equipped at the upper part of said drilling cutter (6); and each end of said auger wing next to the other one is reciprocally working to form a continuous wall unit by mixing the in-situ soil with mixed liquid; and if necessary, water retaining character and cut-off power are improved by molding H-type steel and sheet pile to said continuous wall.

[0006] In the aforementioned conventional multi shaft auger machine in the prior art, some triangular irregularities, which are generated by the overlapping outer rotation of drilling cutters, appears longitudinally on both sides of the continuous wall unit obtained by the auger shafts; it is not desirable for its strength.

[0007] Therefore, the applicant proposes a new technology to drill a continuous wall unit straight in Japanese Patent Application Publication No. 2-115406.

[0008] According to contents of Japanese Patent Application Publication No.2-115406, chain drive drilling cutters are provided angularly close to the lower ends of the auger shafts ; this is quite effective. According to said prior art disclosed in Japanese Patent Application Publication No. 2-115406, however, there is a problem with respect to the reliability because the machine is chain driven and the chains are apt to loosen or damage.

Summary

[0009] An object of the present invention is to propose a highly reliable multi-shaft drilling unit to develop a continuous wall in a straight line-shape in consideration of the aforementioned problems involving said prior art.

[0010] The housing equipped in the multi-shaft drilling unit providing three auger shafts used to develop a continuous wall under the ground in the present invention desirably comprising: a primary transfer means rotating around the central auger shaft; a pair of secondary transfer means engaging with said primary transfer means; a tertiary transfer means integral with said primary transfer means; a quaternary transfer means engaging with said tertiary transfer means and fixed to a rotary shaft orthogonally crossing a line connecting said auger shaft centers; and cone-shaped cutters that expand to the side direction are fixed to both ends of said rotary shaft.

[0011] According to an embodiment in the present invention, for example, gears are desirably used as the primary and secondary transfer means, and bevel gears are desirably used as the tertiary and quaternary transfer means. In this case said primary transfer means is the primary gear; the secondary transfer means is the secondary gear; the tertiary transfer means is the primary bevel gear; and the quaternary transfer means is the secondary bevel gear.

[0012] Additionally, "cone-shaped" means the shape of cutters includes a circular cone and a truncated cone.

[0013] Besides, according to an embodiment in the present invention, a guide shaft is desirably provided on one side of said line of the drilling unit equipped with a plurality of drilling shafts, centers of which shafts are arranged on a line. In addition, it is also desirable to provide a guide shaft on both sides of the drilling unit equipped with a plurality of drilling shafts of which the shaft centers are arranged on a line, as well. Furthermore, a jet nozzle is desirably equipped with said guide shaft. Said guide shaft is desirably equipped with a tubular guide bit on which a concavity is formed overlapping to a bit of drilling shaft; and said guide shaft desirably equips a pair of jet nozzles toward a tangent line outside the guide.

[0014] According to said multi-shaft drilling unit being constructed as above-mentioned, a triangular convex, which has conventionally been remained, can be completely cut off by using cutters, and a continuous wall unit, both ends of which form a semicircle and both sides of which form a straight line, can be formed.

[0015] According to the present invention, since said cutter is cone-shaped such as truncated cone-shaped, almost triangular convex (it has not been drilled previously) can be drilled and the remaining convex will naturally collapse by tare weight, vibration or other events, even if the pitch between auger shafts became longer. In other words, the pitch between auger shafts can lengthen in the present invention. This can reduce the time and labor to form a continuous wall unit.

[0016] In addition, when a guide shaft is provided on one side of a line of the drilling unit equipping a plurality of drilling shafts centers of which shaft are arranged on the line, a guide hole is drilled firstly and the guide hole guides a guide shaft to drill a hole by the drilling shaft. As a result, a plurality of continuous holes can be drilled in good linearity since the guide shaft receives a reaction force. Additionally, since a hole at the end of the primary drilling hole, at which the drilling is completed, is applied as a guide hole, the continuity to the secondary drilling hole can be remained. Besides, if the unit is constructed such that a jet stream is injected from a jet nozzle, a cross section of subsoil will be drilled in wedge-shaped and a drilling wing (in some cases, cone-shaped cutters, too), as well as said drilling, will be washed by cone-shaped cutters desirably.

Brief Description of the Drawings

[0017] The following explains the preferred embodiment of the present invention making reference to the attached drawings.

[0018] Fig. 1 is a schematic front view showing a pivotal part of an embodiment in the present invention.
Fig. 2 is a side view of Fig. 1.
Fig. 3 is a horizontal section view showing details.
Fig. 4 is a section view showing an A-B-C-E line of Fig. 3.
Fig. 5 is a side view showing a conventional unit of the prior art.
Fig. 6 is a front view showing an auger shaft of Fig. 5.
Fig. 7 is a front view showing a preferred embodiment of a continuous multi-shaft drilling unit.
Fig. 8 is a drawing showing the lower part of Fig. 7.
Fig. 9 is a section view showing a A-A line in Fig. 8.
Fig. 10 is a front view showing a guide bit.
Fig. 11 is a section view showing a B-B line in Fig. 10.
Fig. 12 is a section view showing a C-C line in Fig. 10.
Fig. 13 is a plan view explaining a state of drilling.
Fig. 14 is a front view explaining a state of drilling.
Fig. 15 is a front view explaining the other state of guide bit position.
Fig. 16 is a front view explaining the other state of guide bit position.
Fig. 17 is a plan view explaining the other state of drilling.
Fig. 18 is a side view showing the other embodiment of a continuous multi-shaft drilling unit.
Fig. 19 is a front view showing a continuous multi shaft drilling unit of Fig. 18.

Embodiment

[0019] In Fig. 1 and Fig. 2, a pitch between the auger shafts (5A, 5B and 5C) remains by the housing (11) of the cutter drive unit (10) provided with the bearings; two pairs of cutters (22) described as follows are equipped on said unit (10) parallel to a straight line (L) connecting shaft centers of the drilling shafts (5).

[0020] In Fig. 3 or Fig. 4, the housing (11) of the cutter drive unit (10) is formed in H-shaped by the primary part (12) including a straight line (L) and the two secondary parts (13) orthogonally crossing a straight line (L) at an intermediate point of each shaft (5).

[0021] The primary gear (the primary transfer means) (14) is connected to the auger shaft (5B) in serration; the primary gear (14) is engaged with a pair of secondary gears (the secondary transfer means) (15) which are arranged on the straight line (L) in the primary part (12); the secondary gears (15) are connected by a key to a shaft (17) which is vertically placed in the primary bevel gear (the tertiary transfer means) (18) projecting into the secondary part (13) which is fixed on the upper part of the shaft (17).

[0022] On the other hand, a rotary shaft (19) is placed in the secondary part (13) through three pairs of bearings (20); the secondary bevel gear (the quaternary transfer means) (21) engaging with the primary bevel gear (18) is connected by key on the side of two pairs of bearings (20) of said rotary shaft (19); a cutter (22) is fixed on both sides of the drive shaft (19); and the outer cutter (22) is formed in cone-shaped (in truncated cone-shaped in the illustrated example) expanding toward the sides to cut an outer triangular convex (A) generated on both sides of a straight line (L) by the outer rotation loci (D) of drilling cutters (6) (Fig. 6) which overlap alternately.

[0023] Therefore, when the auger shafts (5A, 5B and 5C) rotate in the arrow head direction during drilling, a pair of cutters (22, 22) (Fig. 1) will rotate in opposite directions as shown by an arrow to cut the outer part (A) through the primary gear (14), secondary gear (15), primary bevel gear (18) and secondary bevel gear (21). As a result, a range of subsoil (S) of which both ends form a semicircle and both sides form a straight line is drilled by three outer rotation loci (D) and the outer surfaces of four cutters (22) to form a continuous wall unit (U). In this case, since such cutters (22, 22) rotate in opposing directions, the rotary reaction force is relieved in good balance. In addition, a part (A1) is not cut in Fig. 3, but, the part (A1) is very small and thus negligible.

[0024] In addition, auger shafts (e.g. auger shaft, 5A on left side) on both sides can be moved on a straight line (L) by the moving capacity (E) within the range that can be neglected for the uncut part (A2).

[0025] Since said cutter (22) is constructed in truncated cone-shaped, almost of part A can be drilled and the remaining convex at which the cutter did not reach will naturally collapse by tare weight, vibration or other events even if the pitch between auger shafts (5A, 5B and 5C) became longer. Therefore, the time, labor and the other costs can be reduced to form a continuous wall unit by lengthening the pitch between auger shafts (5A, 5B and 5C).

[0026] Fig. 7 to Fig. 19 show a remarkably preferred embodiment of a continuous multi-shaft drilling unit in combination with the present invention.

[0027] In Fig. 7 to Fig. 9, the shaft centers of a plurality (three in the example of Fig. 7 to Fig. 9) of movable drilling shafts (110A, 110B and 110C - hereinafter referred to as just "110" collectively) and a immovable guide shaft (111) are arranged on a straight line (L) at the same pitch. Those drilling shafts (110A to 110C) are mutually connected by interference prevention brackets (112) serving as a plurality of bearings; and clamp brackets (113A) that lock a guide shaft (111) selectively are connected to several brackets (112A) of such brackets (112).

[0028] Referring to Fig. 10 to Fig. 12 as well, a guide bit (114) is provided at the lower end of the guide shaft (111).

[0029] The body (115) of the guide bit is tubular; the part overlapped with a drilling cutter (106) of a drilling shaft (110A) and with an outer rotation locus (D) of a movable wing (107) [both of them and an outer diameter 〈R〉 of an auger wing (108) are equally formed] is formed on a circular concavity (116); and a pair of jet nozzles (117), that inject a jet stream (J) toward a tangent line are equipped in circumference of the body (115) parallel to a straight line (L).

[0030] Said jet stream (J) injected from said jet nozzles (117) is injected toward the direction that can wash the cutters (22) (Fig. 1 to Fig. 4) or is arranged at a position where it does not interfere with the cutters (22).

[0031] The following explains the state of drilling by a continuous multi-shaft drilling unit shown in Fig. 7 to Fig. 12. As shown in Fig. 13, guide holes (H1, H2, etc.) are drilled in advance; and as shown in Fig. 14, a guide bit (114) is inserted to the guide hole (H1) at first and holes (h1, h2 and h3) are drilled by drilling shafts (110A, 110B and 110C) to drill the subsoil in wedge-shaped by a jet stream (J); doing the same operation to the guide hole (H2), that is to say, holes (h1, h2 and h3) are drilled to drill the subsoil continuously in wedge-shaped by the jet stream (J); in this case, since guide holes (H1, H2, etc.) receive drilling reaction force of the drilling shaft (110) through the guide bit (114), the linearity of the wedge-shaped section is remarkably excellent.

[0032] In addition, as shown in Fig. 14, the holes are drilled such that the guide bit (114) lowers by only the length L (e.g. 500mm - 700mm) than the drilling cutter (106) of the drilling shaft (110). In this case, guiding by the guide bit (114) is good, however, some operation that the clamp of the guide shaft (111) can be released by a clamp block (113B) and a guide bit (114) can be free before the length L showing a scheduled drilling depth as required.

[0033] On the contrary, as shown in Fig. 15, when drilling is done at the same level of a guide bit (114) and a drilling cutter (106) on the subsoil, or as shown in Fig. 16, when drilling is done in a state where a guide bit (114) is pulled up by the length D1 (e.g. 300mm to 550mm) than a drilling cutter (106), the release of a clamp of the guide bit (114) will not be required as above mentioned, however, since the guiding ability slightly decreases, it is desirable for the unstable ground.

[0034] Fig. 17 shows the other embodiment of drilling. When the first drilling on a guide hole (H1) is completed, the second drilling will be executed as such a hole (h3) is a guide hole. In this case, the linearity is further desirable and a need of a jet stream (J) can be decreased in comparison with the aforementioned embodiment.

[0035] Fig. 18 and Fig. 19 show the other embodiment in the present invention exemplifying that guide shafts (111, 111A) are separately equipped on both sides of each drilling shaft (110A to 110C). According to this embodiment, as shown in Fig. 13, guide holes (H1, H2) are used and the jet stream (J) is oppositely injected from such holes to do drilling so that the linearity can further be improved.

[0036] Besides, the embodiment as illustrated is just an example, therefore, the new technology employed in the present invention is not limited to said embodiment. For example, the primary gear, secondary gear, primary bevel gear and secondary bevel gear correspond to the transfer means (primary to quaternary) in the illustrated embodiment, however, the other rolling transfer mechanism can be employed.

Effect of the Invention

[0037] The effects of the present invention are enumerated as follows:

(1) Wedge-shaped continuous wall unit can be formed.

(2) Since the cutter reaction force is relieved, the balance is good enough.

(3) Various costs on forming a continuous wall are remarkably decreased by lengthening the pitch between auger shafts.

(4) Drilling range can be expanded by moving the auger shafts on both sides to slightly outward.

(5) The reliability is much higher in comparison with a chain drive since a gear drive can be employed.

Claims

1. A multi-shaft drilling unit equipped with three auger shafts used to develop a continuous wall under the ground comprised of: a housing which retains the pitch between said auger shafts; in said housing comprising;
   a primary transfer means rotating around the central auger shaft;
   a pair of secondary transfer means engaging with said primary transfer means;
   a tertiary transfer means integral to said primary transfer means;
   a quaternary transfer means engaging with said primary transfer means and being fixed to a rotary shaft orthogonally crossing a straight line connecting said auger shaft centers; and
   cone-shaped cutters expanding the diameter outward are fixed on both ends of said rotary shaft.

Drawing