Lightweight aggregate concrete conveying pipeline

Abstract

The utility model discloses a conveying pipeline of light aggregate concrete, which relates to the field of concrete conveying and comprises a conveying pipeline main body, a first moving groove and a second moving groove which are symmetrical to each other are arranged above the conveying pipeline main body, and a detection inner plate is attached to the inner surface of the conveying pipeline main body. A first through groove corresponding to the first moving groove is formed in the upper surface of the detection inner plate, a second through groove corresponding to the second moving groove is formed in the upper surface of the detection inner plate, and a first push-pull rod is fixedly installed in the first through groove. By shaking the first push-pull rod and the second push-pull rod, which section of pipeline is blocked can be known without disassembling the pipeline, the specific position of the blockage can be quickly found, the time for finding the blockage is shortened, time is won for maintenance, concrete coagulation caused by too long time is avoided, and the pipeline blockage detection device is easy to operate, simple in structure and convenient to manufacture without disassembling.

Description

Technical Field

[0001] The utility model relates to the field of concrete transportation, in particular to a transportation pipeline for light aggregate concrete. Background Art

[0002] Due to its lightweight aggregate characteristics, lightweight aggregate concrete has poorer fluidity and stability than ordinary concrete. This makes lightweight aggregate concrete more susceptible to friction and shear force inside the pipeline during transportation, resulting in reduced fluidity and easy blockage. The water-cement ratio of lightweight aggregate concrete has a crucial influence on its fluidity and stability. If the water-cement ratio is too large, the concrete will be too thin, with good fluidity but poor stability, and it will easily form separation and water seepage in the pipeline, leading to blockage. Conversely, if the water-cement ratio is too small, the concrete will have poor fluidity and will not flow smoothly in the pipeline, which can also easily cause blockage.

[0003] Lightweight aggregate concrete needs to be lubricated with water before being transported in pipelines; the main purpose of doing this is to reduce the friction between the concrete and the inner wall of the pipeline, improve the fluidity of the concrete, and prevent blockage.

[0004] Due to its specific composition and properties, lightweight aggregate concrete is easily affected by friction when flowing in pipes. If the inner wall of the pipe is not smooth or has uneven areas, the friction will be greater, which can easily lead to a decrease in the flow rate of concrete or even blockage. By lubricating the inner wall of the pipe with water, a layer of water film can be formed to reduce the direct contact between the concrete and the pipe, thereby reducing friction resistance and allowing the concrete to flow more smoothly.

[0005] In addition, lubricating the pipes with water can also clean the pipes, flushing away residues and impurities on the inner walls of the pipes, keeping the pipes clean and unobstructed; this is also very important for preventing blockages.

[0006] Traditionally, when a blockage occurs, the specific location of the blockage is often found one section at a time, and then the location is dismantled, the lightweight aggregate concrete inside is poured out, and then tools are used to clear the blockage. This method not only takes a long time to find the blockage location, but also requires dismantling and pouring out the concrete, resulting in some concrete being wasted. The process is complicated and difficult to operate, and it is easy to cause waste and dirt in the working area.

[0007] Therefore, it is necessary to propose a lightweight aggregate concrete delivery pipeline to solve the above problems. Utility Model Content

[0008] The utility model aims to provide a lightweight aggregate concrete conveying pipeline to solve the above-mentioned problems of difficulty in finding the blocking position, difficulty in cleaning the blocking position and complex cleaning process.

[0009] To achieve the above-mentioned purpose, the utility model provides the following technical solutions: a conveying pipeline for lightweight aggregate concrete, comprising a conveying pipeline main body, a first movable groove and a second movable groove which are symmetrical to each other are opened on the top of the conveying pipeline main body, a detection inner plate is attached to the inner surface of the conveying pipeline main body, a first through groove corresponding to the first movable groove is opened on the upper surface of the detection inner plate, a second through groove corresponding to the second movable groove is opened on the upper surface of the detection inner plate, a first push-pull rod is fixedly installed inside the first through groove, a second push-pull rod is fixedly installed inside the second through groove, the first push-pull rod is movably clamped inside the first movable groove, the second push-pull rod is movably clamped inside the second movable groove, a connecting groove body is opened in the middle of the detection inner plate, and a plurality of evenly distributed spraying grooves are opened on both sides of the connecting groove body.

[0010] Preferably, the first push-pull rod and the second push-pull rod extend to the outside of the conveying pipe body, and one end of the first push-pull rod and the second push-pull rod extending to the outside of the conveying pipe body are both installed with a connecting threaded cylinder through integral molding, and the first push-pull rod and the second push-pull rod are both hollow cylindrical structures, the interior of the first push-pull rod is connected to the first through groove, and the interior of the second push-pull rod is connected to the second through groove.

[0011] Preferably, the first through groove and the second through groove are both connected to the connecting groove body, one end of the plurality of spraying grooves is connected to the connecting groove body, and one end of the plurality of spraying grooves away from the connecting groove body is connected to the interior of the conveying pipeline body.

[0012] Preferably, the spraying groove is in an arc shape, and the radius of the arc is equal to the inner circle radius of the conveying pipeline body.

[0013] Preferably, a first sealing ring body is installed at a position on the outer ring of the conveying pipe body corresponding to the first movable groove, and a second sealing ring body is installed at a position on the outer ring of the conveying pipe body corresponding to the second movable groove, the first push-pull rod is fixedly installed on the first sealing ring body, and the second push-pull rod is fixedly installed on the second sealing ring body.

[0014] Preferably, the first sealing ring body and the second sealing ring body both include a sealing outer ring body, a mounting groove is provided on the top of the sealing outer ring body, two symmetrical sealing inner ring bodies are rotatably clamped inside the sealing outer ring body, a rubber ring is rotatably sleeved on the outer ring of the sealing inner ring body, the rubber ring is tightly attached to the inner wall of the sealing groove, the two sealing inner ring bodies are fixedly mounted on the outer surface of the conveying pipeline body, the two sealing inner ring bodies are respectively located on both sides of the first push-pull rod or the second push-pull rod, and the first push-pull rod and the second push-pull rod are respectively fixedly mounted inside the two mounting grooves.

[0015] Preferably, splicing plates are fixedly installed at both ends of the conveying pipeline body.

[0016] Preferably, both sides of the first through groove are provided with chamfers.

[0017] Technical effects and advantages of the utility model:

[0018] 1. The utility model sets a detection inner plate, shakes the first push-pull rod and the second push-pull rod, and can find out which section of the pipeline is blocked without disassembling the pipeline, and can quickly find out the specific location of the blockage, reducing the time for finding the blockage, saving time for maintenance, and avoiding concrete coagulation due to too long time. It is simple to operate without disassembly, and has a simple structure and is easy to manufacture;

[0019] 2. After pushing the first push-pull rod and the second push-pull rod to find the blocked position, repeatedly shake the first push-pull rod and the second push-pull rod with force, thereby driving the detection inner plate to squeeze the blocked position and try to dredge the blocked position. If the blockage is relatively firm, high-pressure water flow is introduced into the interior of the conveying pipe body through the first push-pull rod and the second push-pull rod, and then the water flow flows into the interior of the spraying slot through the connecting slot body, and finally sprays out to the inner wall of the conveying pipe body through the spraying slot, thereby impacting the blocked position, making the blocked position easier to be cleaned. The blocked position can be cleaned without disassembling the pipe, which is simple and practical.

[0020] 3. Before transporting concrete, a small amount of water is introduced to clean and lubricate the inner wall of the conveying pipe body. This will reduce the friction between the concrete and the conveying pipe body when transporting concrete, making it less likely to be blocked and easier to transport. When the transport span is too high, the concrete is likely to solidify due to evaporation. Therefore, during transportation, the first push-pull rod and the second push-pull rod can be used to replenish water to the concrete to prevent it from solidifying. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a structural schematic diagram of a conveying pipeline for lightweight aggregate concrete of the utility model.

[0022] Figure 2 It is a structural schematic diagram of the conveying pipeline main body in the utility model.

[0023] Figure 3 It is a schematic diagram of the connection structure between the detection inner plate and the first push-pull rod in the utility model.

[0024] Figure 4 It is a schematic diagram of the structure of the detection inner plate and the first push-pull rod in the utility model.

[0025] Figure 5 For this utility model Figure 4 Cross-section view of the middle BB position.

[0026] Figure 6 For this utility model Figure 4 Cross-section view at the AA position.

[0027] Figure 7 It is a structural schematic diagram of the first sealing ring body in the utility model.

[0028] In the figure: 1. Conveying pipeline body; 2. Detection inner plate; 3. First push-pull rod; 4. First sealing ring body; 5. Second sealing ring body; 6. Splicing plate; 11. First movable groove; 12. Second movable groove; 21. First through groove; 22. Second through groove; 23. Connecting groove body; 24. Spraying groove; 31. Second push-pull rod; 32. Connecting threaded cylinder; 40. Sealing outer ring body; 41. Mounting groove; 42. Sealing inner ring body; 43. Sealing groove; 44. Rubber ring. DETAILED DESCRIPTION

[0029] The following will be combined with the drawings in the embodiments of the utility model to clearly and completely describe the technical solutions in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments in the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0030] The utility model provides Figure 1-Figure 7 The light aggregate concrete conveying pipeline shown in the figure comprises a conveying pipeline body 1, both ends of which are fixedly installed with splicing plates 6, a first movable groove 11 and a second movable groove 12 symmetrically provided on the upper side of the conveying pipeline body 1, a detection inner plate 2 is attached to the inner surface of the conveying pipeline body 1, a first through groove 21 corresponding to the first movable groove 11 is provided on the upper surface of the detection inner plate 2, chamfers are provided on both sides of the first through groove 21, a second through groove 22 corresponding to the second movable groove 12 is provided on the upper surface of the detection inner plate 2, a first push-pull rod 3 is fixedly installed inside the first through groove 21, and the first push-pull rod 3 can move inside the first movable groove 11, and the second push-pull rod 31 is fixedly installed inside the second through groove 22, and the second push-pull rod 31 can move inside the second movable groove 12. When the first push-pull rod 3 and the second push-pull rod 31 move from one end of the first movable groove 11 and the second movable groove 12 to the other end, the detection inner plate 2 will slide along the inner wall of the conveying pipe body 1, the first push-pull rod 3 is movably arranged inside the first movable groove 11, and the second push-pull rod 31 is movably arranged inside the second movable groove 12, and the first push-pull rod 3 and the second push-pull rod 31 extend to the outside of the conveying pipe body 1.

[0031] In actual use, multiple splicing plates 6 on the device are spliced ​​with screws to form an integral conveying pipeline, which is then used to convey lightweight aggregate concrete. Due to its lightweight aggregate characteristics, lightweight aggregate concrete has poorer fluidity and stability than ordinary concrete. This makes lightweight aggregate concrete more susceptible to friction and shear force inside the pipeline during pipeline transportation, resulting in reduced fluidity and easy blockage. The water-cement ratio of lightweight aggregate concrete has a crucial influence on its fluidity and stability. If the water-cement ratio is too large, the concrete will be too thin, with too good fluidity but poor stability, and it will easily form separation and water seepage in the pipeline, causing blockage. Conversely, if the water-cement ratio is too small, the concrete will have poor fluidity and will not flow smoothly in the pipeline, which will also easily cause blockage.

[0032] When a blockage occurs, it is necessary to quickly find the location of the blockage, otherwise the transported concrete inside it will easily solidify and cause the entire pipeline to be blocked, which not only causes damage to the pipeline, but also leads to waste of concrete raw materials. Traditionally, when encountering a blockage, the specific blockage location is often found section by section of the pipeline, and then the location is disassembled, the light aggregate concrete inside is poured out, and then tools are used to clear the blockage. This method not only takes a long time to find the blockage location, but also requires disassembly and then pouring out the concrete, resulting in part of the concrete being wasted. The process is complicated and difficult to operate, which can easily cause waste and dirty working areas.

[0033] Therefore, the utility model sets the detection inner plate 2. When a blockage occurs, it is only necessary to rotate the first push-pull rod 3 and the second push-pull rod 31 on each section of the device to drive the detection inner plate 2 to rotate inside the conveying pipeline body 1. If there is no blockage, the first push-pull rod 3 and the second push-pull rod 31 can be easily rotated. When a certain section of the pipeline is blocked, the detection inner plate 2 will be blocked due to the blockage, making it difficult to rotate. Therefore, it is possible to know which specific section of the pipeline is blocked without disassembling the pipeline, and the specific location of the blockage can be quickly found, which reduces the time for finding the blockage, saves time for maintenance, and avoids concrete solidification due to a long time. It is simple to operate without disassembly, and the structure is simple and easy to manufacture.

[0034] A connecting groove body 23 is opened in the middle of the detection inner plate 2, and multiple evenly distributed spraying grooves 24 are opened on both sides of the connecting groove body 23. The spraying groove 24 is arc-shaped, and the radius of the arc is equal to the inner circle radius of the conveying pipe body 1. The first push-pull rod 3 and the second push-pull rod 31 extend to the outside of the conveying pipe body 1. One end is installed with a connecting threaded cylinder 32 through integral molding. The first push-pull rod 3 and the second push-pull rod 31 are both hollow cylindrical structures. The interior of the first push-pull rod 3 is connected to the first through groove 21, and the interior of the second push-pull rod 31 is connected to the second through groove 22. The first through groove 21 and the second through groove 22 are both connected to the connecting groove body 23, one end of the multiple spraying grooves 24 is connected to the connecting groove body 23, and the end of the multiple spraying grooves 24 away from the connecting groove body 23 is connected to the interior of the conveying pipe body 1.

[0035] Lightweight aggregate concrete needs to be lubricated with water before being transported in pipelines; the main purpose of doing this is to reduce the friction between the concrete and the inner wall of the pipeline, improve the fluidity of the concrete, and prevent blockage.

[0036] Due to its specific composition and properties, lightweight aggregate concrete is easily affected by friction when flowing in pipes. If the inner wall of the pipe is not smooth or has uneven areas, the friction will be greater, which can easily lead to a decrease in the flow rate of concrete or even blockage. By lubricating the inner wall of the pipe with water, a layer of water film can be formed to reduce the direct contact between the concrete and the pipe, thereby reducing friction resistance and allowing the concrete to flow more smoothly.

[0037] In addition, lubricating the pipes with water can also clean the pipes, flushing away residues and impurities on the inner walls of the pipes, keeping the pipes clean and unobstructed; this is also very important for preventing blockages.

[0038] Before use, the first push-pull rod 3 and the second push-pull rod 31 are connected to the external co-concentration pipeline through the connecting threaded tube 32. Before transporting concrete, a small amount of water is introduced to clean and lubricate the inner wall of the conveying pipeline body 1. In this way, when transporting concrete, the friction between the concrete and the conveying pipeline body 1 can be reduced, and it is not easy to be blocked, making it easier to transport. When the transportation span is too high, the concrete is easy to solidify due to evaporation. Therefore, during transportation, the first push-pull rod 3 and the second push-pull rod 31 can be used to replenish water to the concrete to prevent it from solidifying.

[0039] After pushing the first push-pull rod 3 and the second push-pull rod 31 to find the blocked position, shake the first push-pull rod 3 and the second push-pull rod 31 repeatedly with force, thereby driving the detection inner plate 2 to squeeze the blocked position and try to clear the blocked position. If the blockage is relatively firm, high-pressure water flow is introduced into the interior of the conveying pipe body 1 through the first push-pull rod 3 and the second push-pull rod 31, and then the water flow flows into the interior of the spraying groove 24 through the connecting groove body 23, and finally sprayed onto the inner wall of the conveying pipe body 1 through the spraying groove 24, thereby impacting the blocked position, making the blocked position easier to clean. The blocked position can be cleaned without disassembling the pipe, which is simple and practical.

[0040] After use, the inside of the pipe needs to be cleaned everywhere, otherwise concrete will condense on the inner wall of the pipe. Traditional cleaning almost always uses water to fill the pipe and then clean it. Filling the pipe requires a lot of water to be wasted, and because the pressure is more dispersed, the cleaning effect on the inner wall of the pipe is not good.

[0041] The device is provided with a spraying groove 24. Because the spraying groove 24 is designed to be arc-shaped, the water flowing out of the interior thereof can directly impact the inner wall of the conveying pipe body 1. The inner wall of the conveying pipe body 1 is circular, so the flushing water flow will form an annular water flow on the inner wall of the conveying pipe body 1, and the impact on various parts inside the pipe is relatively large, which can achieve a better cleaning effect.

[0042] A first sealing ring body 4 is installed at a position corresponding to the first movable groove 11 on the outer ring of the conveying pipe body 1, and a second sealing ring body 5 is installed at a position corresponding to the second movable groove 12 on the outer ring of the conveying pipe body 1. The first push-pull rod 3 is fixedly installed on the first sealing ring body 4, and the second push-pull rod 31 is fixedly installed on the second sealing ring body 5. The first sealing ring body 4 and the second sealing ring body 5 both include a sealing outer ring body 40, and a mounting groove 41 is opened on the top of the sealing outer ring body 40. Two symmetrical sealing inner ring bodies 42 are rotatably clamped inside the sealing outer ring body 40. A rubber ring 44 is rotatably sleeved on the outer ring of the sealing inner ring body 42, and the rubber ring 44 is tightly attached to the inner wall of the sealing groove 43. The two sealing inner ring bodies 42 are both fixedly installed on the outer surface of the conveying pipe body 1, and the two sealing inner ring bodies 42 are respectively located on both sides of the first push-pull rod 3 or the second push-pull rod 31, and the first push-pull rod 3 and the second push-pull rod 31 are respectively fixedly installed inside the two mounting grooves 41.

[0043] In order to ensure the sealing inside the conveying pipe body 1, when the first push-pull rod 3 and the second push-pull rod 31 move, the sealing outer ring body 40 will be driven to rotate, and the rubber ring 44 can tightly press against the inner wall of the sealing groove 43. Then, when the sealing outer ring body 40 rotates, the sealing inside the first sealing ring body 4 can be ensured, so that the water flow inside the conveying pipe body 1 will not overflow.

[0044] Working principle: In actual use, multiple splicing plates 6 on the device are spliced ​​with screws to form an integral conveying pipeline, which is then used to convey lightweight aggregate concrete. When blockage occurs, it is only necessary to rotate the first push-pull rod 3 and the second push-pull rod 31 on each section of the device to drive the detection inner plate 2 to rotate inside the conveying pipeline body 1. If there is no blockage, the first push-pull rod 3 and the second push-pull rod 31 can be easily rotated. When a section of the pipeline is blocked, the detection inner plate 2 will be blocked due to the blockage, making it difficult to rotate. Therefore, it is possible to know which specific section of the pipeline is blocked without disassembling the pipeline. In order to ensure the sealing inside the conveying pipeline body 1, when the first push-pull rod 3 and the second push-pull rod 31 move, the sealing outer ring body 40 will be driven to rotate, and the rubber ring 44 can tightly press against the inner wall of the sealing groove 43. Then, when the sealing outer ring body 40 rotates, the sealing inside the first sealing ring body 4 can be guaranteed, so that the water flow inside the conveying pipeline body 1 will not overflow.

[0045] After pushing the first push-pull rod 3 and the second push-pull rod 31 to find the blocked position, shake the first push-pull rod 3 and the second push-pull rod 31 repeatedly with force, thereby driving the detection inner plate 2 to squeeze the blocked position and try to clear the blocked position. If the blockage is relatively firm, high-pressure water flow is introduced into the interior of the conveying pipe body 1 through the first push-pull rod 3 and the second push-pull rod 31, and then the water flow flows into the interior of the spraying groove 24 through the connecting groove body 23, and finally sprayed onto the inner wall of the conveying pipe body 1 through the spraying groove 24. Because the spraying groove 24 is designed to be arc-shaped, the water flow flowing out of it can directly impact the inner wall of the conveying pipe body 1, and the inner wall of the conveying pipe body 1 is circular, so the flushed water flow will form an annular water flow on the inner wall of the conveying pipe body 1.

[0046] Before use, the first push-pull rod 3 and the second push-pull rod 31 are connected to the external co-concentration pipeline through the connecting threaded tube 32. Before transporting concrete, a small amount of water is introduced to clean and lubricate the inner wall of the conveying pipeline body 1. In this way, when transporting concrete, the friction between the concrete and the conveying pipeline body 1 can be reduced, and it is not easy to be blocked, making it easier to transport. When the transportation span is too high, the concrete is easy to solidify due to evaporation. Therefore, during transportation, the first push-pull rod 3 and the second push-pull rod 31 can be used to replenish water to the concrete to prevent it from solidifying.

[0047] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A lightweight aggregate concrete delivery pipeline, comprising a delivery pipeline body (1), characterized in that: A first movable groove (11) and a second movable groove (12) which are symmetrical to each other are provided on the upper side of the conveying pipe body (1); a detection inner plate (2) is attached to the inner surface of the conveying pipe body (1); a first through groove (21) corresponding to the first movable groove (11) is provided on the upper surface of the detection inner plate (2); a second through groove (22) corresponding to the second movable groove (12) is provided on the upper surface of the detection inner plate (2); a first push-pull rod (3) is fixedly installed inside the first through groove (21); a second push-pull rod (31) is fixedly installed inside the second through groove (22); the first push-pull rod (3) is movably mounted inside the first movable groove (11); the second push-pull rod (31) is movably mounted inside the second movable groove (12); a connecting groove body (23) is provided in the middle of the detection inner plate (2); and a plurality of evenly distributed spraying grooves (24) are provided on both sides of the connecting groove body (23).

2. A lightweight aggregate concrete delivery pipeline according to claim 1, characterized in that: The first push-pull rod (3) and the second push-pull rod (31) extend to the outside of the conveying pipe body (1); one end of the first push-pull rod (3) and the second push-pull rod (31) extending to the outside of the conveying pipe body (1) are both integrally formed with a connecting threaded cylinder (32); the first push-pull rod (3) and the second push-pull rod (31) are both hollow cylindrical structures; the interior of the first push-pull rod (3) is connected to the first through groove (21), and the interior of the second push-pull rod (31) is connected to the second through groove (22).

3. A lightweight aggregate concrete delivery pipeline according to claim 1, characterized in that: The first through groove (21) and the second through groove (22) are both in communication with the connecting groove body (23), one end of the plurality of spraying grooves (24) is in communication with the connecting groove body (23), and one end of the plurality of spraying grooves (24) away from the connecting groove body (23) is in communication with the interior of the conveying pipeline body (1).

4. The lightweight aggregate concrete delivery pipeline according to claim 1, characterized in that: The spraying groove (24) is in an arc shape, and the radius of the arc is equal to the inner circle radius of the conveying pipeline body (1).

5. The lightweight aggregate concrete delivery pipeline according to claim 1, characterized in that: A first sealing ring body (4) is installed at a position on the outer ring of the conveying pipe body (1) corresponding to the first movable groove (11), and a second sealing ring body (5) is installed at a position on the outer ring of the conveying pipe body (1) corresponding to the second movable groove (12). The first push-pull rod (3) is fixedly installed on the first sealing ring body (4), and the second push-pull rod (31) is fixedly installed on the second sealing ring body (5).

6. A lightweight aggregate concrete delivery pipeline according to claim 5, characterized in that: The first sealing ring body (4) and the second sealing ring body (5) both comprise a sealing outer ring body (40), a mounting groove (41) is provided on the top of the sealing outer ring body (40), two symmetrical sealing inner ring bodies (42) are rotatably mounted inside the sealing outer ring body (40), a rubber ring (44) is rotatably sleeved on the outer ring of the sealing inner ring body (42), the rubber ring (44) is tightly attached to the inner wall of the sealing groove (43), the two sealing inner ring bodies (42) are both fixedly mounted on the outer surface of the conveying pipeline body (1), the two sealing inner ring bodies (42) are respectively located on both sides of the first push-pull rod (3) or the second push-pull rod (31), and the first push-pull rod (3) and the second push-pull rod (31) are respectively fixedly mounted inside the two mounting grooves (41).

7. The lightweight aggregate concrete delivery pipeline according to claim 1, characterized in that: Both ends of the conveying pipeline body (1) are fixedly mounted with splicing plates (6).

8. The lightweight aggregate concrete delivery pipeline according to claim 1, characterized in that: Both sides of the first through groove (21) are provided with chamfers.

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