Cast-in-place pile head separating device

Abstract

The utility model discloses a cast-in-place pile head separating device which is characterized in that the bottom end of a pile head is located at the top of a cast-in-place pile body, the cast-in-place pile head separating device comprises a pile head reinforcing steel bar, the pile head reinforcing steel bar is sleeved with an isolation sleeve, a breaking pipe is arranged at the bottom end of the pile head reinforcing steel bar, and a plurality of breaking teeth and supporting teeth which can stretch out of the breaking pipe are distributed in the breaking pipe in the axial direction. In the concrete pouring process, the supporting teeth are located outside the breaking pipe, and the breaking teeth are located in the breaking pipe; after the concrete is solidified, the supporting teeth are located in the breaking pipe, and the breaking teeth are located outside the breaking pipe. The concrete crusher is convenient for quickly crushing concrete of the pile head.

Description

TECHNICAL FIELD

[0001] The utility model relates to a cast-in-place pile technical field, concretely relates to a cast-in-place pile pile head separating device. BACKGROUND

[0002] Cast-in-place pile is a kind of deep foundation structure formed by drilling in foundation, placing reinforcement cage and pouring concrete, and is widely used in high-rise building, bridge, port and other engineering.The core function is to transfer upper load to deep stable soil or rock layer to solve the problem of soft soil or insufficient bearing capacity in shallow layer.However, pile head part (i.e.the connecting area of pile top and pile cap) needs to be broken after cast-in-place pile construction to expose reinforcement and ensure pile cap connection quality.

[0003] Traditional pile head processing technology mainly relies on manual chiseling or mechanical cutting, and manual chiseling is time-consuming and labor-consuming, and mechanical cutting equipment is high in cost and complex in operation, especially in dense pile group construction, efficiency is difficult to meet the construction period requirement. UTILITY MODEL CONTENT

[0004] The utility model aims at providing a cast-in-place pile pile head separating device, which is convenient for quickly breaking the concrete of pile head.

[0005] To solve the above technical problems, the utility model adopts the following scheme:

[0006] A cast-in-place pile pile head separating device, the bottom end of pile head is located at the top of the main body of cast-in-place pile, including pile head reinforcement, the pile head reinforcement is provided with an isolation sleeve, the bottom end of pile head reinforcement is provided with a breaking pipe, a plurality of breaking teeth and support teeth that can extend to outside the breaking pipe are distributed in the breaking pipe in the axial direction, in the process of pouring concrete, the support teeth are located outside the breaking pipe, and the breaking teeth are located in the breaking pipe;after the concrete solidifies, the support teeth are located in the breaking pipe, and the breaking teeth are located outside the breaking pipe.The function is that, by the setting of support teeth, the concrete can be solidified outside the support teeth, then the support teeth are withdrawn to make the concrete form a cavity for accommodating the support teeth, so that the overall structure of the concrete can be broken from the inside;by the setting of breaking teeth, the overall structure of the concrete can be damaged from the inside after the concrete solidifies;by the combined setting of support teeth and breaking teeth, the concrete of pile head can be quickly broken.

[0007] Further, the top of the bottom end of pile head is provided with a protective ring, the breaking pipe is arranged through the protective ring, and all pile head reinforcement, breaking teeth and support teeth are located in the internal cavity of the protective ring.The function is that, by the setting of protective ring, the concrete can be limited in the internal cavity of protective ring, to avoid blocking the front and back ends of breaking pipe and prevent the concrete from flowing out from the gap at the height of breaking pipe.

[0008] Further, the breaking pipe comprises a transverse breaking pipe and a longitudinal breaking pipe, the transverse breaking pipe is vertically arranged with the longitudinal breaking pipe, the transverse breaking pipe and the longitudinal breaking pipe are vertically arranged with the pile head reinforcement, and the transverse breaking pipe and the longitudinal breaking pipe are located at different heights of the pile head reinforcement. Through the design of the spatial relationship between the breaking pipe and the pile head reinforcement, the pile head reinforcement can be prevented from hindering the extension of the breaking tooth.

[0009] Further, the protection ring comprises an upper ring, a middle ring and a lower ring which are distributed along the axial direction of the protection ring, the transverse breaking pipe is located above the longitudinal breaking pipe, the transverse breaking pipe is located between the upper ring and the middle ring, and the longitudinal breaking pipe is located between the middle ring and the lower ring. Since the support tooth is located outside the breaking pipe and cannot be inserted into the protection ring along the axial direction, the breaking pipe can be conveniently installed in the protection ring through the design of the upper ring, the middle ring and the lower ring.

[0010] Further, the breaking pipe is hingedly connected with the support tooth, the breaking pipe is provided with a breaking opening for the extension of the breaking tooth, and the breaking opening is embedded with a sealing plate for sealing the breaking opening during the pouring process. Through the hingedly connected arrangement of the support tooth and the breaking pipe, any rod-shaped object (such as a steel bar) can be inserted into the breaking pipe, the support tooth can be pushed to turn inward and thus be retracted into the breaking pipe, and since the support tooth is retracted in the form of rotation, the resistance to the retraction of the support tooth is small.

[0011] Further, the breaking pipe is provided with a symmetry plane, the axis of the breaking pipe is located in the symmetry plane, and the support tooth is symmetrically arranged on opposite sides of the symmetry plane.

[0012] Further, the breaking pipe comprises an upper half pipe and a lower half pipe which are symmetrically arranged on two sides of a plane perpendicular to the symmetry plane, the upper half pipe is provided with an upper half shaft in the concave surface, the lower half pipe is provided with a lower half shaft in the concave surface, the upper half shaft and the lower half shaft are coaxially arranged, and the support tooth is sleeved outside the whole formed by the upper half shaft and the lower half shaft in the state that the upper half pipe and the lower half pipe form the breaking pipe. Through the arrangement of the upper half pipe, the lower half pipe, the upper half shaft and the lower half shaft, the installation of the support tooth and the breaking tooth in the breaking pipe can be facilitated.

[0013] Further, the support tooth is in the form of a column with a fan-shaped cross section, the support tooth comprises a cylindrical surface and a side plane which are located outside the breaking pipe during the pouring of concrete, and a stress receiving section which is located inside the breaking pipe during the pouring of concrete, the lower half shaft is located between the cylindrical surface and the stress receiving section, the inner diameter of the surface of the breaking pipe in contact with the cylindrical surface is the same as the outer diameter of the cylindrical surface, and an extension plate extending to the outside of the cylindrical surface is embedded on the side plane. The extension plate is made of elastic material and is in interference fit with the side plane. Through the design of the size of the cylindrical surface and the surface of the breaking pipe in contact with the cylindrical surface, the cylindrical surface and the surface of the breaking pipe in contact with the cylindrical surface can play a certain sealing role while not hindering the rotation of the support tooth; through the arrangement of the extension plate, the support tooth can be conveniently kept outside the breaking pipe.

[0014] Further, the driving rod has a cross section in the shape of a circle and an extension connected to the circle, the breaking pipe is provided with a rotating cylinder, the middle part of the rotating cylinder is provided with a lock hole having the same cross section as the driving rod, the rotating cylinder is externally threadedly connected with a sleeve, the outer wall of the sleeve is provided with an inclined block, and the inclined block is in contact with the breaking tooth.

[0015] Further, the sleeve is provided with an inclined block on each of the opposite sides, the upper half pipe and the lower half pipe are provided with clamping plates on the left and right sides of the inclined block, and the cross section of the breaking tooth is the same as that of the breaking hole.

[0016] The utility model has the beneficial effects of:

[0017] 1. The support tooth is arranged to enable the concrete to solidify outside the support tooth, and then the support tooth is withdrawn to form a cavity in the concrete for accommodating the support tooth, thereby facilitating the breaking of the overall structure of the concrete from the inside; the breaking tooth is arranged to enable the overall structure of the concrete to be broken from the inside out after the concrete solidifies; and the combination of the support tooth and the breaking tooth enables the concrete of the pile head to be quickly broken.

[0018] 2. Since the support tooth is located outside the breaking pipe, the breaking pipe cannot be moved axially to be inserted into the protective ring, and the upper ring, the middle ring and the lower ring are designed to facilitate the installation of the breaking pipe in the protective ring.

[0019] 3. The support tooth is hingedly connected to the breaking pipe, so that any rod-shaped object (such as a reinforcing bar) can be inserted into the breaking pipe to push the support tooth to turn inward and be withdrawn into the breaking pipe, and since the support tooth is withdrawn in a rotating manner, the resistance of the concrete is small. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 It is a schematic diagram of the three-dimensional structure of Example 1.

[0021] Figure 2 It is a schematic diagram of the sectional structure of Example 1.

[0022] Figure 3 It is a schematic diagram of the sectional structure of Example 1. Figure 2 It is a schematic diagram of the sectional structure of Example 1.

[0023] Figure 4 It is a schematic diagram of the sectional structure of Example 1. It is a schematic diagram of the sectional structure of Example 1.

[0024] Figure 5 This is a three-dimensional structural diagram of the breaking tube in Example 1, excluding the upper half of the tube;

[0025] Figure 6 for Figure 5 Enlarged structural diagram at point B;

[0026] Figure 7 This is a three-dimensional structural diagram of the drive rod in Example 1;

[0027] Figure 8 for Figure 7 A magnified structural diagram at point C.

[0028] Reference numerals in the attached drawings: 1. Main body of the cast-in-place pile; 2. Reinforcing steel bar at the pile head; 3. Isolation sleeve; 4. Breaking pipe; 401. Transverse breaking pipe; 402. Longitudinal breaking pipe; 5. Breaking tooth; 6. Support tooth; 7. Protective ring; 701. Upper ring; 702. Middle ring; 703. Lower ring; 8. Breaking opening; 9. Sealing plate; 10. Upper half pipe; 11. Lower half pipe; 12. Upper half shaft; 13. Lower half shaft; 14. Cylindrical surface; 15. Side plane; 16. Stress-bearing section; 17. Extension plate; 18. Drive rod; 19. Extension section; 20. Rotary cylinder; 21. Sleeve; 22. Locking hole; 23. Inclined block; 24. Clamping plate. Detailed Implementation

[0029] The present invention will be further described in detail below with reference to the embodiments and accompanying drawings, but the implementation of the present invention is not limited thereto.

[0030] In the description of this utility model, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "longitudinal", "lateral", "horizontal", "inner", "outer", "front", "rear", "top", "bottom", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the utility model product is in use. They are only for the convenience of describing this utility model and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model.

[0031] In the description of this utility model, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set up," "have," "install," "connect," and "connect" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific circumstances.

[0032] Example 1

[0033] A pile head separation device for cast-in-place piles, such as Figure 1 As shown, the bottom end of the pile head is located at the top of the main body 1 of the cast-in-place pile, including the pile head reinforcement 2. The pile head reinforcement 2 is covered with an isolation sleeve 3. A breaking tube 4 is provided on the bottom end of the pile head reinforcement 2. Multiple breaking teeth 5 and support teeth 6 that can extend out of the breaking tube 4 are distributed axially inside the breaking tube 4. During the concrete pouring process, the support teeth 6 are located outside the breaking tube 4, and the breaking teeth 5 are located inside the breaking tube 4. After the concrete solidifies, the support teeth 6 are located inside the breaking tube 4, and the breaking teeth 5 are located outside the breaking tube 4. Its function is that, by setting the support teeth 6, the concrete can solidify outside the support teeth 6, and then the support teeth 6 can be retracted to form a cavity in the concrete to accommodate the support teeth 6, which facilitates the breaking of the overall structure of the concrete from the inside. By setting the breaking teeth 5, the overall structure of the concrete can be broken from the inside out after the concrete solidifies. The combination of the support teeth 6 and the breaking teeth 5 can quickly break the concrete of the pile head.

[0034] Specifically, such as Figure 1 As shown, a protective ring 7 is provided at the top of the bottom end of the pile head, and the breaking pipe 4 is installed through the protective ring 7. All pile head reinforcing bars 2, breaking teeth 5, and support teeth 6 are located inside the cavity of the protective ring 7. Its function is to confine the concrete within the cavity of the protective ring 7, preventing concrete from blocking the front and rear ends of the breaking pipe 4 and preventing concrete from flowing out from the gap at the height of the breaking pipe 4.

[0035] Specifically, such as Figure 1 As shown, the breaking tube 4 includes a transverse breaking tube 401 and a longitudinal breaking tube 402. The transverse breaking tube 401 and the longitudinal breaking tube 402 are arranged perpendicularly to each other. Both the transverse breaking tube 401 and the longitudinal breaking tube 402 are arranged perpendicularly to the pile head reinforcement 2, and the transverse breaking tube 401 and the longitudinal breaking tube 402 are located at different heights of the pile head reinforcement 2. Its function is to prevent the pile head reinforcement 2 from obstructing the extension of the breaking teeth 5 through the spatial relationship design between the breaking tube 4 and the pile head reinforcement 2.

[0036] Specifically, such as Figure 2 As shown, the protective ring 7 includes an upper ring 701, a middle ring 702, and a lower ring 703 distributed along the axial direction of the protective ring 7. A transverse breaking tube 401 is located above the longitudinal breaking tube 402, between the upper ring 701 and the middle ring 702, and between the middle ring 702 and the lower ring 703. Its function is that, since the supporting teeth 6 are located outside the breaking tube 4, it is impossible to move the breaking tube 4 axially into the protective ring 7. The design of the upper ring 701, middle ring 702, and lower ring 703 facilitates the installation of the breaking tube 4 within the protective ring 7.

[0037] Specifically, as shown in Figure 4 The support tooth 6 is hinged in the breaking pipe 4, and the breaking pipe 4 is provided with a breaking opening 8 for the support tooth 5 to extend out of the breaking pipe 4. The breaking opening 8 is embedded with a sealing plate 9 for closing the breaking opening 8 during the pouring process. Through the hinged arrangement of the support tooth 6 and the breaking pipe 4, any rod (such as a steel bar) can be inserted into the breaking pipe 4 to push the support tooth 6 to turn inward and be retracted into the breaking pipe 4. Since the support tooth 6 is retracted in a rotating manner, the resistance to the retraction is small.

[0038] Specifically, as shown in Figure 3 The breaking pipe 4 is provided with a symmetry plane, the axis of the breaking pipe 4 is located in the symmetry plane, and the support tooth 6 is symmetrically arranged on opposite sides of the symmetry plane.

[0039] Specifically, as shown in Figure 3 The breaking pipe 4 includes an upper half pipe 10 and a lower half pipe 11 symmetrically arranged on both sides of a plane perpendicular to the symmetry plane. The upper half pipe 10 is provided with an upper half shaft 12 in the concave surface, and the lower half pipe 11 is provided with a lower half shaft 13 in the concave surface. The upper half shaft 12 and the lower half shaft 13 are coaxially arranged. In the state that the upper half pipe 10 and the lower half pipe 11 form the breaking pipe 4, the support tooth 6 is sleeved outside the whole formed by the upper half shaft 12 and the lower half shaft 13. Through the arrangement of the upper half pipe 10, the lower half pipe 11, the upper half shaft 12, and the lower half shaft 13, the installation of the support tooth 6 and the breaking tooth 5 in the breaking pipe 4 is facilitated.

[0040] Specifically, as shown in Figure 5 , Figure 6 The support tooth 6 is in the shape of a cylinder with a fan-shaped cross section. The support tooth 6 includes a cylindrical surface 14 and a side plane 15 located outside the breaking pipe 4 during the pouring of concrete, and a stress section 16 located inside the breaking pipe 4 during the pouring of concrete. The lower half shaft 13 is located between the cylindrical surface 14 and the stress section 16. The inner diameter of the surface of the breaking pipe 4 in contact with the cylindrical surface 14 is the same as the outer diameter of the cylindrical surface 14. The side plane 15 is embedded with an extension plate 17 extending out of the cylindrical surface 14. The extension plate 17 is made of elastic material and is in interference fit with the side plane 15. Through the design of the size of the cylindrical surface 14 and the surface of the breaking pipe 4 in contact with the cylindrical surface 14, the cylindrical surface 14 and the surface of the breaking pipe 4 in contact with the cylindrical surface 14 can play a certain sealing role while not hindering the rotation of the support tooth 6. Through the arrangement of the extension plate 17, the support tooth 6 can be kept outside the breaking pipe 4.

[0041] Specifically, as shown in Figure 7 The drive rod 18 is further included, as shown in Figure 8As shown, the cross-section of the drive rod 18 includes a circle and an extension 19 connected to the circle. A rotating cylinder 20 is provided inside the breaking tube 4. A locking hole 22 with the same cross-section as the drive rod 18 is located in the middle of the rotating cylinder 20. A sleeve 21 is externally threaded onto the rotating cylinder 20. An inclined block 23 is provided on the outer wall of the sleeve 21, and the inclined block 23 contacts the breaking teeth 5. The inclined block 23 is inclined along the axial direction of the breaking tube 4. Its function is that, through the arrangement of the drive rod 18, locking hole 22, rotating cylinder 20, sleeve 21, and inclined block 23, the breaking teeth 5 can be pushed out of the breaking tube 4 by rotating the drive rod 18.

[0042] Specifically, such as Figure 6 As shown, the sleeve 21 has inclined blocks 23 on both opposite sides. The upper half-tube 10 and lower half-tube 11 are each equipped with clamping plates 24 located on the left and right sides of the inclined blocks 23. The cross-section of the breaking teeth 5 is the same as the cross-section of the breaking opening 8. The inclined blocks 23 are interference-fitted with the two adjacent clamping plates 24. Their function is to guide the movement direction of the inclined blocks 23 through the clamping plates 24; and through the design of the dimensional relationship between the breaking teeth 5 and the breaking opening 8, the breaking teeth 5 can only move radially along the breaking tube 4.

[0043] The working principle of this embodiment is explained as follows: First, the lower ring 703 is placed at the preset height of the bottom of the pile head. Then, the longitudinal breaking pipe 402, the middle ring 702, the transverse breaking pipe 401, and the upper ring 701 are placed on the lower ring 703 in sequence. Then, during the concrete pouring process, a protective sleeve tightly attached to the inner wall of the upper ring 701 is installed inside the upper ring 701. The protective sleeve is cylindrical. The concrete is poured to above the top of the upper ring 701. The distance between the pouring height and the top of the upper ring 701 is greater than the pre-calculated concrete settlement height. After the concrete solidifies, the protective sleeve is removed, and the drive rod 18 is inserted into the breaking pipe 4, so that the drive rod 18 passes through the locking hole 22. The drive rod 18 moves towards the breaking pipe. During the inward movement of the 4th tube, the drive rod 18 pushes the force-bearing section 16, causing the support tooth 6 to flip inward into the breaking tube 4. During the inward flipping of the support tooth 6, the extension plate 17 is limited by the solidified concrete and remains in place, separating from the flipped support tooth 6. After the drive rod 18 penetrates into the breaking tube 4, the drive rod 18 is rotated, which drives the rotating drum 20 to rotate. The rotating drum 20 drives the sleeve 21 to move axially along the breaking tube 4 through the thread. At the same time as the rotating drum 20 moves, the inclined rod moves axially along the breaking tube 4, thereby pushing the breaking tooth 5 out of the breaking opening 8 to cut the concrete outside the breaking tube 4. At the same time as the breaking tooth 5 extends out of the breaking opening 8, the breaking opening 8 pushes open the cover.

[0044] The above merely describes preferred embodiments of the present application, and is not intended to limit the present application in any form. Any simple modification, equivalent replacement, improvement, etc. made to the above embodiments, in accordance with the technical essence of the present application, and within the spirit and principles of the present application, shall still fall within the protection scope of the technical scheme of the present application.

Claims

1. A pile head separation device for cast-in-place piles, wherein the bottom end of the pile head is located at the top of the main body (1) of the cast-in-place pile, and includes pile head reinforcing bars (2), characterized in that: The pile head steel bar (2) is covered with an isolation sleeve (3), and a breaking tube (4) is provided on the bottom end of the pile head steel bar (2). Multiple breaking teeth (5) and support teeth (6) that can be extended to the outside of the breaking tube (4) are distributed axially inside the breaking tube (4). During the concrete pouring process, the support teeth (6) are located outside the breaking tube (4), and the breaking teeth (5) are located inside the breaking tube (4). After the concrete solidifies, the support teeth (6) are located inside the breaking tube (4), and the breaking teeth (5) are located outside the breaking tube (4).

2. The pile head separation device for cast-in-place piles according to claim 1, characterized in that: The top of the bottom end of the pile head is provided with a protective ring (7), and the breaking pipe (4) is set through the protective ring (7). All pile head steel bars (2), breaking teeth (5), and support teeth (6) are located in the internal cavity of the protective ring (7).

3. The pile head separation device for cast-in-place piles according to claim 2, characterized in that: The breaking tube (4) includes a transverse breaking tube (401) and a longitudinal breaking tube (402). The transverse breaking tube (401) and the longitudinal breaking tube (402) are set perpendicularly to each other. Both the transverse breaking tube (401) and the longitudinal breaking tube (402) are set perpendicular to the pile head reinforcement (2). The transverse breaking tube (401) and the longitudinal breaking tube (402) are located at different heights of the pile head reinforcement (2).

4. The pile head separation device for cast-in-place piles according to claim 3, characterized in that: The protective ring (7) includes an upper ring (701), a middle ring (702), and a lower ring (703) distributed along the axial direction of the protective ring (7). The transverse breaking tube (401) is located above the longitudinal breaking tube (402). The transverse breaking tube (401) is located between the upper ring (701) and the middle ring (702). The longitudinal breaking tube (402) is located between the middle ring (702) and the lower ring (703).

5. The pile head separation device for cast-in-place piles according to claim 1, characterized in that: The breaking tube (4) is hinged with a support tooth (6), and the breaking tube (4) is provided with a breaking opening (8) for the breaking tooth (5) to extend out. A sealing plate (9) is embedded in the breaking opening (8) for sealing the breaking opening (8) during the pouring process.

6. The pile head separation device for cast-in-place piles according to claim 5, characterized in that: The breaking tube (4) has a symmetrical plane inside, and the axis of the breaking tube (4) is located in the symmetrical plane. The support teeth (6) are symmetrically arranged on opposite sides of the symmetrical plane.

7. The pile head separation device for cast-in-place piles according to claim 6, characterized in that: The breaking tube (4) includes an upper half tube (10) and a lower half tube (11) symmetrically arranged on both sides of a plane perpendicular to the plane of symmetry. An upper half shaft (12) is provided in the concave surface of the upper half tube (10), and a lower half shaft (13) is provided in the concave surface of the lower half tube (11). The upper half shaft (12) and the lower half shaft (13) are coaxially arranged. When the upper half tube (10) and the lower half tube (11) form the breaking tube (4), the support tooth (6) is sleeved on the outside of the whole formed by the upper half shaft (12) and the lower half shaft (13).

8. The pile head separation device for cast-in-place piles according to claim 7, characterized in that: The support tooth (6) is a column with a fan-shaped cross section. The support tooth (6) includes a cylindrical surface (14) and a side plane (15) located outside the demolition tube (4) when pouring concrete, and a force-bearing section (16) located inside the demolition tube (4) when pouring concrete. The lower half shaft (13) is located between the cylindrical surface (14) and the force-bearing section (16). The inner diameter of the surface of the demolition tube (4) that contacts the cylindrical surface (14) is the same as the outer diameter of the cylindrical surface (14). An extension plate (17) extending outside the cylindrical surface (14) is embedded in the side plane (15).

9. A pile head separation device according to claim 7, characterized in that: It also includes a drive rod (18), the cross-section of which includes a circle and an extension (19) connected to the circle. A rotating cylinder (20) is provided inside the breaking tube (4). A lock hole (22) with the same cross-section as the drive rod (18) is provided in the middle of the rotating cylinder (20). A sleeve (21) is connected to the external thread of the rotating cylinder (20). An inclined block (23) is provided on the outer wall of the sleeve (21). The inclined block (23) contacts the breaking teeth (5).

10. A pile head separation device according to claim 9, characterized in that: The sleeve (21) has inclined blocks (23) on both opposite sides. The upper half pipe (10) and the lower half pipe (11) are provided with clamps (24) located on the left and right sides of the inclined blocks (23). The cross-section of the breaking teeth (5) is the same as the cross-section of the breaking opening (8).

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