Bullet bodies, blades, and culvert excavation devices

Abstract

The present invention provides a projectile, a blade, and a culvert excavation device that can easily correct deviations in the direction of travel when forming a culvert in the deep layers of the ground. [Solution] The culvert excavation device 1 comprises a bullet body 2 and a blade 10. The bullet body 2 comprises a spreading section 3 for spreading the ground 60 and a wall holding section 4 provided behind the spreading section 3 and capable of maintaining the shape of the wall section 61a of the formed culvert 61. The spreading section 3 has a pointed end 6 on the side facing the direction of travel F of the traction means, and the wall holding section 4 has an inclined surface 8 on its circumferential surface that tapers toward the direction B opposite to the direction of travel F.

Description

Technical Field

[0001] The present invention relates to a bullet body for excavating the ground to form a drainage culvert, a blade for fixing the bullet body and attached to a traction means, and a culvert excavation device including the bullet body and the blade. In particular, when forming a culvert in the deep layer of the ground, the present invention relates to a bullet body, a blade, and a culvert excavation device capable of easily correcting the deviation of the blade and the bullet body in the traveling direction.

Background Art

[0002] Conventionally, as a construction method for improving the drainage function of the ground, a sheet pipe method for excavating the shallow layer of the ground 60 (usually 40 to 50 cm underground) has been implemented. As shown in FIG. 10, in this sheet pipe method, a bullet body 50 for pulling a drainage pipe 53 is fixed to a long plate-shaped blade 51, and after attaching the upper end of the blade 51 to an arm 52a of a traction means 52, the traction means 52 is run in the traveling direction F to form a culvert 61 and at the same time lay the pipe 53 in the culvert 61. Further, the pipe 53 is formed into a cylindrical shape from a flat sheet by a sheet pipe forming device 54 as the traction means 52 travels. However, since there has been a demand to bury the pipe 53 not only in the shallow layer but also in the deep layer (about 1 m underground) of the ground 60, when the above sheet pipe method was implemented, the resistance of the soil against the bullet body 50 increased in the deep layer compared to the shallow layer, and problems related to the traveling of the traction means 52 occurred.

[0003] Specifically, the traction means 52 does not travel in a completely straight line, but travels while deviating in the vertical and horizontal directions according to the way of operation and the surface shape of the ground 60. Therefore, the tip of the bullet body 50 also deviates in the vertical and horizontal directions, making it difficult to accurately form the culvert 61 at the designed position. Therefore, it becomes necessary to correct the direction of the tip of the bullet body 50. However, since the soil resistance is large in the deep layer, a small traction means (for example, a hydraulic excavator) has insufficient traction force, and it is difficult to correct the direction of the tip against the soil resistance.

[0004] Furthermore, since the blade 51 is generally long and plate-shaped, and is pressed against the soil on both sides when excavating the ground 60, once the blade 51's posture deviates from side to side, it is difficult to correct its posture with a small towing device, just as with the bullet body 50. To solve this, it would be best to use a larger towing device 52 (for example, a bulldozer) with stronger towing force, but the opportunities to use such a towing device 52 are limited, and it would also be costly. To address these challenges, technologies have been developed that can reduce soil resistance to projectiles, and such designs have already been disclosed.

[0005] Patent Document 1 discloses an invention related to a device for forming drainage channels in the ground of a paddy field, under the title "Agricultural Subsurface Drainage System." The invention disclosed in Patent Document 1 is characterized in that a tillage cutting plate, to which a bullet-shaped projectile is fixed at its lower end, is pivotally attached to the rear of the tractor body via a crank mechanism so as to be able to swing back and forth. In this invention, as the tractor moves forward, the tillage cutting plate begins to reciprocate in the front-to-back direction, causing the projectile to move forward and backward repeatedly underground. Therefore, resistance to the projectile can be reduced compared to conventional methods, and the drainage system can be formed with low horsepower. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Publication No. 49-146741 [Overview of the Initiative] [Problems that the invention aims to solve]

[0007] In the invention disclosed in Patent Document 1, since the tillage plate and the bullet are pivotally attached to the rear of the tractor body via a crank mechanism, if the tractor body moves while swaying up and down and left and right, there is a risk that the rear of the bullet may collide with the wall of the culvert when it retracts. In addition, since the cross-section of the tillage plate is a long, narrow rectangle along the direction of traction, it may be difficult to correct the sway with low horsepower. In other words, it may become difficult for the tillage plate and bullet to repeatedly move forward and backward, which may prevent the formation of a culvert with low horsepower.

[0008] This invention addresses the aforementioned conventional circumstances and aims to provide a projectile, blade, and culvert excavation device that can easily correct deviations in the direction of travel when forming a culvert in the deep layers of the ground. [Means for solving the problem]

[0009] To achieve the above objective, the first invention is a bullet-shaped device that is pulled by a traction means via a blade to excavate a culvert in the ground, comprising a spreading section for spreading the ground and a wall-holding section provided behind the spreading section and capable of maintaining the shape of the formed culvert wall, wherein the spreading section has a pointed end formed on the side facing the direction of travel of the traction means, and the wall-holding section has an inclined surface that tapers in the direction opposite to the direction of travel, except for at least the lower region of its circumferential surface.

[0010] In this design, when the expanding portion is viewed from the side, it has, for example, an acute triangular shape. Furthermore, the cross-section of the rear end of the expanding portion, i.e., the connection point with the wall-holding portion, is circular. This is because it is assumed that the pipe installed inside the culvert is cylindrical. Next, the wall support section has a tapered inclined surface that tapers in the direction opposite to the direction of travel, thus forming a roughly frustoconical shape. Furthermore, the area below the circumferential surface of the wall support section is the area of ​​the culvert wall where the bottom surface can be formed.

[0011] In the above-described configuration, the culvert is excavated by the expanding section pushing and expanding the ground. However, since an inclined surface is formed in the wall-holding section, a gap is formed between the wall-holding section and the wall of the culvert. Therefore, if the projectile is pulled in a straight line as designed, the formed gap will remain as is. In contrast, when the traction mechanism moves while swaying vertically and horizontally, the tip of the projectile and the wall-holding part also sway in the same direction. Therefore, it is necessary to tilt the tip of the projectile in the opposite direction to the direction of the sway. Even in this case, a gap is formed between the wall-holding part and the wall of the culvert, making it difficult for the inclined surface to come into contact with the wall of the culvert. Thus, it is easy to correct the direction of the tip, and after correcting the direction of the tip, it is prevented from colliding with the wall of the culvert where the inclined surface has formed and damaging the shape of the wall.

[0012] Furthermore, since this invention addresses the problem of easily correcting deviations in the direction of travel of the blade and projectile when forming a culvert in the deep layers of the ground, the inclined surface occupies a particularly lower region of the wall-holding part, making it easier for the tip to tilt towards the deeper layers and facilitating directional correction when the tip deviates from side to side.

[0013] The second invention is characterized in that, in the first invention, it is provided with an excess length portion, the excess length portion being provided between the spreading portion and the wall holding portion. In this configuration, the excess length portion is, for example, cylindrical and is fixed to the lower end of the blade together with the wall-holding portion. In the above configuration, in addition to the effects of the first configuration, the bullet body is pulled, causing wear due to soil resistance near the rear end of the expanding portion, making it prone to deformation. By providing an excess length, the culvert can be formed in a certain shape (for example, a circular shape) even as wear progresses.

[0014] The third invention is a blade whose upper end is attached to a traction means and which holds a bullet-shaped body that forms a culvert in the ground at its lower end, comprising a front portion facing the direction of travel of the traction means and a rear portion connected to the front portion, wherein the periphery of the cross-section of the front portion is formed in an arc shape or an angular shape, and the width of the cross-section of the rear portion narrows in the direction away from the front portion.

[0015] A blade of this configuration is for holding a projectile according to the first or second invention, and is generally thin and plate-like. The width of the cross-section of the rear section is the width in the thickness direction of the blade, and is aligned in a direction approximately perpendicular to the direction of travel of the traction means. Furthermore, since the width of the cross-section of the rear section narrows in the direction away from the front section, a gap is formed between the wall of the groove formed by the front section excavating into the ground and the rear section. Therefore, even when the towing mechanism moves while swaying up and down or left and right, the rear part is less likely to come into contact with the wall of the groove, making it easier to correct the direction in which the front part of the blade is facing.

[0016] The fourth invention relates to the length L of the upper end of the blade along the front-to-back direction. U The length L along the vertical direction of the blade is equal to or greater than the length obtained by dividing the length L into four parts, and the length L U The length L of the lower end along the front-to-back direction is... L The above is the characteristic feature. In this configuration, in addition to the function of the third invention, the length L of the upper end is also U By ensuring that the length is greater than or equal to the length obtained by dividing the length L into four parts, a certain level of rigidity is ensured along the front-to-back direction of the blade.

[0017] Also, length L U The length of the lower end is L. L Of the above, length L U is length L L In the case of longer blades, when viewed from the side, the blade becomes roughly wedge-shaped, reducing the surface area of ​​the blade's sides compared to a rectangular shape. As a result, the soil resistance on both sides of the blade is reduced.

[0018] The fifth invention is a culvert excavation device characterized by comprising at least one of the bullet body described in the first or second invention and the blade described in the third or fourth invention. In such a configuration, the invention may also include (1) a bullet body as described in the first or second and a blade as described in the third or fourth, (2) a bullet body as described in the first or second and a blade other than that described in the third or fourth, or (3) a bullet body other than that described in the first or second and a blade as described in the third or fourth. In the above configuration, the action of the bullet body described in the first or second section and the action of the blade described in the third or fourth section are performed simultaneously, or either one of these actions is performed. [Effects of the Invention]

[0019] According to the first invention, since the inclined surface of the wall-holding part is less likely to come into contact with the wall of the culvert, it is less likely to be hindered in correcting the direction of the tip of the expanding part, so that deviations in the direction of travel of the projectile can be easily corrected when forming a culvert in the deep layers of the ground. Therefore, by pulling with a traction device with a small traction force, a straight culvert as designed can be formed. Furthermore, since correcting the direction of the tip prevents damage to the shape of the culvert wall, the pipe can be buried without locally tilting it.

[0020] According to the second invention, in addition to the effects of the first invention, the provision of an excess length allows the culvert to be formed in a constant shape even as wear progresses, thereby reducing the frequency of bullet replacement.

[0021] According to the third design, the direction in which the front part of the blade faces can be easily corrected, so it does not hinder the correction of the direction of the bullet's tip. Therefore, if the trajectory of the culvert is about to curve to the left or right, it can be quickly corrected.

[0022] According to the fourth invention, in addition to the effects of the third invention, a certain level of rigidity is ensured along the front-rear direction of the blade, so it is expected that damage due to resistance from the soil can be prevented when the blade is towed. Furthermore, because the blade is roughly wedge-shaped, the soil resistance on both sides of the blade is reduced, so it is expected that the blade can be towed with less pulling force.

[0023] According to the fifth invention, the effects of the bullet body described in the first or second invention and the effects of the blade described in the third or fourth invention are exhibited simultaneously, or either of these effects. [Brief explanation of the drawing]

[0024] [Figure 1] This is a side view of a drainage excavation device according to an embodiment. [Figure 2] This is a perspective view of a drainage excavation device according to an embodiment. [Figure 3] This is a plan view of the bullet-shaped body constituting the underground drainage excavation device according to the embodiment, as seen from above. [Figure 4] This is a rear view of the bullet body, seen from the rear. [Figure 5] This is a cross-sectional view of a blade constituting a culvert excavation device according to an embodiment. [Figure 6] This is a plan view of the bullet as seen from above. [Figure 7] This is a left side view of the bullet, as seen from the left side. [Figure 8] This is a left side view of the bullet, as seen from the left side. [Figure 9] This is a cross-sectional view of the blade. [Figure 10] This is an explanatory diagram of the conventional sheet pipe construction method. [Modes for carrying out the invention] [Examples]

[0025] The culvert excavation device according to the embodiment of the present invention will be described in detail with reference to FIGS. 1 to 9. FIG. 1 is a side view of the culvert excavation device according to the embodiment. FIG. 2 is a perspective view of the culvert excavation device according to the embodiment. As shown in FIGS. 1 and 2, the culvert excavation device 1 according to the embodiment includes a bullet body 2 and a blade 10. Among these, the bullet body 2 is a jig that is pulled by a traction means (not shown) that travels on the ground surface 60a via the blade 10 to excavate a culvert 61 in the soil. And this bullet body 2 includes a pushing and expanding part 3 for pushing and expanding the ground 60, a wall holding part 4, an extra length part 5 provided between the pushing and expanding part 3 and the wall holding part 4, and locking claws 9, 9 for locking the tip of the pipe 53 (see FIG. 10). In this embodiment, a small hydraulic excavator is assumed as the traction means. Further, the blade 10 is a member whose upper end 10a is attached to the arm of the traction means and holds the bullet body 2 at the lower end 10b, and includes a front part 11 facing the traveling direction F of the traction means and a rear part 12 continuous with this front part 11. Further, as shown in FIG. 1, the blade 10 has a maximum length in its front-rear direction X (that is, the length L of the upper end 10a) U ) is longer than the length L / 4 obtained by dividing the length L along the vertical direction Y of the blade 10 into four parts.

[0026] Next, the configuration of the bullet body 2 will be described in detail with reference to FIGS. 3 and 4. FIG. 3 is a plan view when the bullet body constituting the culvert excavation device according to the embodiment is viewed from above. FIG. 4 is a rear view when the bullet body is viewed from the rear. As shown in FIG. 3, the pushing and expanding part 3 of the bullet body 2 is provided for pushing and expanding the ground 60, and a tip part 6 is formed on the side in the traveling direction F of the traction means. This tip part 6 is an acute angle (45 degrees) corner part arranged closer to the deep layer of the ground 60 (see FIG. 1). Also, between the tip part 6 and the extra length part 5, a mountain-shaped edge 7 rising upward from the tip part 6 is formed. The soil of the ground 60 is efficiently crushed by this edge 7. And the crushed soil moves obliquely downward along the semicircular inclined surfaces 7a, 7a sandwiching the edge 7 and constitutes a part of the wall part 61a of the culvert 61. Furthermore, the circumferential surface of the rear end 3a of the expanding portion 3 is circular in shape with diameter A, and is connected to the front end 5a of the excess length portion 5, which is cylindrical in shape and also has diameter A.

[0027] Next, the wall-holding portion 4 is connected to the rear end 5b of the excess length portion 5. This wall-holding portion 4 has an inclined surface 8 that tapers in the direction B opposite to the direction of travel F, and is frustoconical in shape. Furthermore, the front end 4a, the inclined surface 8, and the rear end surface 4b of the wall-holding portion 4 are all rotationally symmetric with respect to the central axis A2 of the bullet body 2. In addition, the angle θ8 between the circumferential surface 5A of the excess length portion 5 and the inclined surface 8 is approximately 18 degrees, and is also rotationally symmetric with respect to the central axis A2. Furthermore, the diameter of the front end 4a is equal to the diameter A of the rear end 3a of the expanded portion 3, and the diameter B of the rear end surface 4b is approximately 2 / 3 of the diameter A.

[0028] Therefore, as shown in Figure 4, the inclined surface 8 occupies the upper region R1, the right region R2, the left region R4, and the lower region R3 of the circumferential surface 4A of the wall holding portion 4. In other words, the inclined surface 8 is provided over the entire circumferential surface 4A of the wall holding portion 4. For convenience, these upper region R1 to left region R4 are regions obtained by dividing the circumferential surface 4A into 90-degree sections with respect to the central axis A2 of the bullet body 2, and when the culvert 61 is viewed from the rear, these regions form the ceiling, right side, bottom, and left side of the wall portion 61a, respectively.

[0029] Next, the configuration of the blade 10 will be described in detail using Figure 5. Figure 5 is a cross-section of the blade that constitutes the culvert excavation device according to the embodiment. As shown in Figure 5, the front portion 11 of the blade 10 is formed in an arc shape, where the periphery in any cross-section S is part of a circle with diameter C, and has a front end surface 11a at the very front. Furthermore, the rear section 12 is surrounded by the side surfaces 12a, 12a and the rear end surface 12b. In addition, on the side surfaces 12a, 12a, the width W in the direction perpendicular to the front-rear direction X narrows along the direction away from the front section 11. Therefore, the width D of the rear end surface 12b is approximately 1 / 4 of the diameter C. The blade 10 has a central axis A along its front-to-back direction X. 10The shape is symmetrical, and the tangent L of the front part 11 in the front-rear direction X is 11 The angle θ between the rear section 12 and the side surfaces 12a, 12a 12 The size is approximately 14 degrees. 12 The size is the same in the vertical direction Y of the blade 10. Also, the central axis A of the blade 10 10 It lies on the same axis as the central axis A2 of the bullet body 2.

[0030] Next, the side shape of the blade 10 will be explained again using Figure 1. As shown in Figure 1, the length L of the upper end 10a along the front-rear direction X of the blade 10 is shown. U The length L along the vertical direction Y of the blade 10 is longer than the length L / 4 obtained by dividing the length L by four. Also, the length L of the upper end 10a is U The length L of the lower end 10b along the front-to-back direction X is L It is longer than that. For example, length L is the length (e.g., 1.5m) that allows the bullet body 2 to reach a deep layer (about 1m underground). In this case, length L of the upper end 10a U The length is 40cm, with the lower end being 10b. L The length is 20 cm. In addition, the rear end surface 12b of the rear section 12 is inclined at an angle of approximately 15 degrees relative to the front end surface 11a of the front section 11. Furthermore, the lower end 10b fixes the bullet body 2 in the range from the excess length portion 5 to approximately half the length of the wall holding portion 4. Therefore, the length over which the rear end surface 4b of the wall holding portion 4 protrudes from the rear end surface 12b of the rear portion 12 is short.

[0031] Next, the action of the projectile body 2 will be explained using Figure 6. Figure 6 is a plan view of the projectile body as seen from above. In the wall-holding portion 4 of the bullet body 2, there is an angle θ8 between the circumferential surface 5A of the excess length portion 5 and the inclined surface 8 (see Figure 3). Therefore, when the bullet body 2 travels without wobbling in the left-right direction, the angle θ8 between the inclined surface 8 and the wall portion 61a of the culvert 61 is maintained. Thus, the inclined surface 8 is less likely to come into contact with the wall portion 61a, and damage to the wall portion 61a is prevented. In other words, the shape of the wall portion 61a can be maintained by providing the inclined surface 8.

[0032] However, the direction of travel F of the traction means 52 is off, causing the bullet body 2 to deviate from the correct trajectory axis A of the culvert 61. 61 From left R L If it proceeds with a bend, angles θ8 and θ8 will each become angle θ 8R ,θ 8L It changes to this. At this time, the angle θ 8R If >0, there is a gap S between the inclined surface 8 and the wall portion 61a. 8R Because of this, it is difficult for the projectile 2 to come into contact with the wall portion 61a of the culvert 61 on which the inclined surface 8 is formed. Therefore, even if the projectile 2 bends as it travels, the inclined surface 8 may be able to maintain the shape of the wall portion 61a. If, for example, the inclined surface 8 is not provided and the angle θ8 does not exist, as shown by the dashed line, the inclined surface 8 will inevitably come into contact with the wall portion 61a, and this wall portion 61a will be damaged. In addition, as explained using Figure 1, because the length of the rear end surface 4b of the wall holding portion 4 protruding from the rear end surface 12b of the rear portion 12 is short, even if the inclined surface 8 of the wall holding portion 4 comes into contact with the wall portion 61a, the contact area is small, making it difficult for the wall portion 61a to be damaged.

[0033] Furthermore, when the orientation of the bullet body 2 bends, its tip 6 moves to the left R L And the opposite right direction R R To return to the correct trajectory, it becomes necessary to change the direction of travel F of the traction means 52 by a steering angle α. Here, the steering angle α is the correct trajectory axis A 61 This is the angle between the central axis A2 of the bullet body 2 before bending (i.e., the central axis A2 after bending). At this time, the angle θ 8L >0 creates a gap S between the inclined surface 8 and the wall portion 61a. 8L Therefore, the rightward R of the inclined surface 8 R The tilting motion is not hindered. Therefore, the tip 6 of the bullet body 2 is directed to the right in the R direction. R No strong force is required to return it to its original position. Furthermore, bullet body 2 is on the correct trajectory axis A. 61 From there, turn right (R) R Even when bending in the same direction as described above, the tip 6 of the bullet body 2 is directed leftward R. L It doesn't require much force to return to its original state.

[0034] Furthermore, the function of the bullet body 2 will be explained using Figures 7 and 8. Both Figures 7 and 8 are left side views of the bullet body as seen from the left side. As shown in Figure 7, the projectile body 2 may float towards the ground surface 60a. This can be caused by the uneven surface of the ground surface 60a, the swinging of the hydraulic excavator arm, or an upward force acting on the projectile body 2 from below by the ground 60. In this case, the central axis A2 of the expanding portion 3 of the projectile body 2 aligns with the correct trajectory axis A of the culvert 61. 61 Upward R U This results in a bend, and due to the angles θ8, θ8 (see Figure 3) which are rotationally symmetric with respect to the central axis A2, the angle θ 8U ,θ 8D This will occur.

[0035] Also, the angle θ 8D If >0, there is a gap S between the inclined surface 8 and the wall portion 61a. 8D Because of this, the inclined surface 8 may not easily come into contact with the wall portion 61a of the culvert 61. If, for example, the inclined surface 8 is not provided and the angle θ8 does not exist, as shown by the dashed line, the inclined surface 8 will inevitably come into contact with the wall portion 61a, and this wall portion 61a will be damaged.

[0036] Furthermore, as the projectile 2 rises toward the ground surface 60a, its tip 6 moves downward R D To return to its original position, it becomes necessary to operate the arm of the hydraulic excavator to push the blade 10 into the ground 60. At this time, the angle θ 8U >0 creates a gap S between the inclined surface 8 and the wall portion 61a. 8U Therefore, the upward R of the inclined surface 8 U The tilting motion is not hindered. Therefore, the tip 6 of the bullet body 2 moves downward R. D It doesn't require much force to return to its original state.

[0037] On the other hand, contrary to the case in Figure 7, as shown in Figure 8, the tip 6 of the bullet body 2 is in the downward direction R. D In some cases, it may descend toward [a certain direction]. In this case as well, due to the angles θ8, θ8 (see Figure 3), the angle θ 8U ,θ 8D This will occur. At this time, the angle θ 8U If >0, there is a gap S between the inclined surface 8 and the wall portion 61a. 8U Therefore, the inclined surface 8 is less likely to come into contact with the wall portion 61a. Also, the tip 6 of the bullet body 2 is directed upward RU To return to the original position, it becomes necessary to pull up the blade 10, but at an angle θ 8D >0 creates a gap S between the inclined surface 8 and the wall portion 61a. 8D Therefore, the downward R of the inclined surface 8 D The tilting motion is not hindered. Therefore, the tip 6 of the bullet body 2 is directed upward R. U It doesn't require much force to return to its original state.

[0038] Next, the function of blade 10 will be explained using Figure 9. Figure 9 is a cross-sectional view of the blade. As shown in Figure 9, as the blade 10, indicated by the dashed line, moves forward, the front section 11 excavates the ground 60, forming a groove 62 with a wall section 62a. The trajectory axis A of this groove 62 62 This is the track axis A of the culvert 61. 61 It lies on the same axis. Also, as shown in Figure 5, the blade 10 is tangent to the front portion 11 in the front-rear direction X L. 11 ,L 11 Then, the sides 12a, 12a of the rear section 12 are at an angle θ 12 ,θ 12 Therefore, a gap S is formed between the sides 12a, 12a of the rear portion 12, shown by the dashed line, and the wall portion 62a. 12 ,S 12 This occurs.

[0039] However, as shown by the solid line, blade 10 moves to the left R L When the movement is erratic, angle θ 12 ,θ 12 As a result, each angle θ 12R ,θ 12L This occurs. Consequently, a gap S 12 ,S 12 However, there is a gap S between the sides 12a, 12a of the rear portion 12 and the walls 62a, 62a of the groove portion 62. 12R ,S 12LIt changes to this. Therefore, the front portion 11 of the blade 10 is turned to the right at a steering angle α R R We return to the angle θ, 12L >0 creates a gap S 12L Therefore, the rightward R of the rear section 12 R The tilting motion is not hindered. Therefore, the front part 11 of the blade 10 is moved to the right in the R direction. R No strong force is required to return it to its original position. Furthermore, the blade 10 is on the correct trajectory axis A. 62 From there, turn right (R) R Even when bending in the same direction as described above, the front portion 11 of the blade 10 is directed to the left (R). L It doesn't require much force to return to its original state.

[0040] As explained above, with the culvert excavation device 1, the gap S8 between the inclined surface 8 and the wall portion 61a makes it difficult for the inclined surface 8 to come into contact with the wall portion 61a of the culvert 61 in which it is formed. Therefore, whether the traction means 52 moves without swaying in the vertical and horizontal directions or moves with swaying, the wall portion 61a, once formed, is less likely to be damaged. In addition, the short length of the rear end surface 4b of the wall holding portion 4 protruding from the rear end surface 12b of the rear portion 12 makes the wall portion 61a less susceptible to damage. Therefore, the pipe 53 can be buried in the ground 60 without locally tilting it. Consequently, a high-quality underground drain can be formed that allows drainage to pass through the pipe 53 without stagnation.

[0041] Furthermore, since the projectile body 2 is provided with an inclined surface 8 that is less likely to come into contact with the wall portion 61a of the culvert 61, strong force is not required to return the direction of the tip 6 of the projectile body 2. Therefore, when forming the culvert 61 in the deep layers of the ground 60, deviations in the direction of travel of the projectile body 2 can be easily corrected. Thus, by towing with a towing means that has a small traction force, such as a hydraulic excavator, a straight culvert 61 as designed can be formed with high precision, and the construction speed for burying the pipe 53 can be shortened.

[0042] Furthermore, because the bullet body 2 has an edge 7, it can efficiently cut through the ground 60 and quickly move the soil crushed by the slopes 7a, 7a, thus shortening the time required to form the underground drainage system 61 compared to conventional methods. In addition, because the bullet body 2 is equipped with an excess length portion 5, it is possible to form the culvert 61 in a constant shape even as wear progresses, thereby reducing the frequency of replacement of the bullet body 2.

[0043] Next, the front portion 11 of the blade 10 has an arc-shaped periphery in its cross-section S, and the sides 12a, 12a of the rear portion 12 have a width W that narrows in the direction away from the front portion 11. Therefore, when the front portion 11 excavates the ground 60, the crushed soil is less likely to adhere to the sides 12a, 12a and is more likely to move backward. Thus, when the blade 10 moves along the direction of travel F, the resistance from the soil can be reduced. Furthermore, when the orientation of the front portion 11 of the blade 10 is altered, the front portion 11 is moved to the right (R). R or left direction R L Since no strong force is required to return it to its original position, it is easy to correct the direction in which the front section 11 faces. Therefore, the track axis A of the groove section 62 62 When the vehicle is about to turn to the left or right, the direction of travel F of the traction means can be quickly corrected.

[0044] In addition, the length L of the upper end 10a along the front-to-back direction X of the blade 10. U Since this is longer than the length L / 4 obtained by dividing the length L of the blade 10 into four parts, a certain level of rigidity is ensured along the front-to-back direction X of the blade 10. Also, the length L of the upper end 10a U The length L of the lower end 10b along the front-to-back direction X is L Because it is longer than, the length L of the upper end 10a U The length L of the lower end 10b L Compared to the case where it is equal to the above, the area of ​​the side surfaces 12a, 12a of the rear portion 12 can be reduced. Therefore, the blade 10 can exhibit excellent effects such as being difficult to break and being able to be towed with little traction force. As described above, according to the underground culvert excavation device 1, by providing the bullet body 2 and the blade 10, when forming an underground culvert in the deep layer of the ground 60, the traveling direction F of the traction means can be quickly corrected, and traction can be performed with a small traction force.

[0045] Note that the bullet body 2, the blade 10, and the underground culvert excavation device 1 according to the present invention are not limited to those shown in the embodiments. For example, the surplus portion 5 may be omitted from the bullet body 2, and the inclined surface 8 may not be provided in the lower region R3 of the wall holding portion 4. Further, the size of the angle θ8 formed by the circumferential surface 5A of the surplus portion 5 and the inclined surface 8 may be other than about 18 degrees. Furthermore, the length L of the upper end 10a of the blade 10 U may be equal to the length obtained by dividing the length L into four parts, and the length L of the lower end 10b <> L may also be equal. In addition, the tangent line L of the front portion 11 in the front-rear direction X 11 and the side surfaces 12a, 12a of the rear portion 12 form an angle θ 12 whose size may be other than about 14 degrees. Also, the bullet body 2, the blade 10, and the underground culvert excavation device 1 may be used to form an underground culvert in the shallow layer of the ground 60. And the underground culvert excavation device 1 may include the bullet body 2, blades other than the blade 10, bullet bodies other than the bullet body 2, and the blade 10.

Industrial Applicability

[0046] The present invention can be used as a bullet body, a blade, and an underground culvert excavation device suitable for forming an underground culvert in the deep layer of the ground.

Explanation of Reference Numerals

[0047] 1…Culvert excavation device 2…Bullet body 3…Expanding section 3a…Rear end 4…Wall holding section 4A…Circumferential surface 4a…Front end 4b…Rear end surface 5…Excess length section 5A…Circumferential surface 5a…Front end 5b…Rear end 6…Tip section 7…Edge 7a…Slope 8…Inclined surface 9…Locking claw 10…Blade 10a…Upper end 10b…Lower end 11…Front section 11a…Front end surface 12…Rear section 12a…Side surface 12b…Rear end surface 50…Bullet body 51…Blade 52…Tracking means 52a…Arm 53…Pipe 54…Sheet pipe forming device 60…Ground 60a…Ground surface 61…Culvert 61a…Wall section 62…Grove section 62a…Wall section

Claims

1. A projectile body that is pulled by a traction means via a blade to excavate a culvert in the ground, A spreading section for expanding the ground, It comprises a wall-holding portion provided behind the expanding portion, which is capable of maintaining the shape of the formed wall portion of the culvert, The spreading portion has a pointed end formed on the side of the direction of travel of the traction means. The bullet body is characterized in that the wall-holding portion has an inclined surface formed on its circumferential surface, other than at least the lower region, which tapers in the direction opposite to the direction of travel.

2. Equipped with an excess length, The bullet body according to claim 1, characterized in that the excess length portion is provided between the expanding portion and the wall holding portion.

3. A blade whose upper end is attached to a traction means and whose lower end holds a bullet-shaped body that forms a culvert in the soil, The forward portion of the traction means in the direction of travel, It comprises a rear section connected to the front section, The aforementioned front portion has a peripheral edge in its cross-section that is formed in an arc shape or an angular shape. The rear portion of the blade is characterized in that the width of its cross-section narrows in the direction away from the front portion.

4. The length L of the upper end of the blade along the front-rear direction Ｕ This length is greater than or equal to the length obtained by dividing the length L along the vertical direction of the blade into four parts. The aforementioned length L Ｕ The length L of the lower end along the front-rear direction is Ｌ The blade according to claim 3, characterized in that it is as described above.

5. A culvert excavation device characterized by comprising at least one of the bullet body described in claim 1 or claim 2 and the blade described in claim 3 or claim 4.

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