Auxiliary tool for mounting middle column bottom plate in steel structure manufacturing

Abstract

The utility model discloses an auxiliary tool for installing a center pillar bottom plate in steel structure manufacturing, and belongs to the technical field of buildings. Comprising a middle column and a bottom plate arranged at the bottom end of the middle column, a plurality of foundation bolts are evenly arranged on the bottom plate in a penetrating mode along the circumference of the middle column, the bottom ends of the foundation bolts are embedded in a cement base body, elevation positioning nuts are connected to the positions, below the bottom plate, of the foundation bolts in a threaded mode, and fastening nuts are connected to the positions, above the bottom plate, of the foundation bolts in a threaded mode. According to the utility model, after the bottom plate of the middle column is placed, the main adjusting plate and the auxiliary adjusting plate are connected together around the middle column, so that the top plate is respectively propped against the four surfaces of the middle column, and then the main adjusting plate and the auxiliary adjusting plate are fixed with a heightened base body or a cement base body through expansion bolts; then, the perpendicularity of the center pillar is measured through a measuring tool, and the threaded rod is rotated to be elongated or shortened to adjust the perpendicularity of the center pillar, so that the aim of effectively and quickly adjusting the perpendicularity of the center pillar is fulfilled.

Description

Technical Field

[0001] The utility model relates to an auxiliary tool for installing a center column bottom plate in steel structure manufacturing, belonging to the technical field of construction. Background Art

[0002] Steel structure is a structure made of steel materials and is one of the main types of building structures. The structure is mainly composed of steel beams, steel columns, steel trusses and other components made of steel sections and steel plates.

[0003] After searching, the patent announcement number is: CN211447495U, a foundation bottom plate steel column installation support structure, including a cushion layer, a waterproof layer, a waterproof protective layer, an embedded component, a support frame, a support plate, an embedded steel column and an embedded shear member, the embedded component includes a horizontal embedded connecting plate, the support frame includes a group of support columns, the bottom end of the support column is connected to the upper surface of the embedded connecting plate, the embedded component also includes embedded legs, and each row of embedded legs and embedded connecting plates are π-shaped. The support device for installing the foundation bottom plate steel column of the utility model can effectively solve the problem that the embedded steel column in the bottom plate cannot be fixedly installed, by adjusting the position of the angle steel support frame by adjusting the positioning of the embedded connecting plate, by adjusting the specifications and dimensions of the angle steel support frame, and by replacing different support plates to meet the buried elevation of the embedded steel column, thereby effectively improving the accuracy of the embedded steel column, and at the same time can meet the support needs of the embedded steel column installation, ensuring the safety and stability of the embedded steel column installation.

[0004] The above scheme achieves the purpose of fixing and stabilizing the steel column by burying the steel column into the foundation to a certain depth. However, when installing the steel column, the verticality of the steel column needs to be adjusted through the elevation positioning nut as in the existing installation technology, which is inconvenient to adjust.

[0005] When installing the center column of the existing steel structure, first, a cement base is built at the installation point, and the anchor bolts are pre-buried in the cement base. Then, the elevation positioning nuts are pre-screwed on the anchor bolts, and the distance between the elevation positioning nuts and the cement base is set. Then, the center column is lifted vertically by a crane so that the bottom plate of the center column is at the bottom, and the center column is slowly released to drop, so that the anchor bolts pass through the mounting holes of the bottom plate, and the bottom plate is placed on the elevation positioning nuts. Then, the fixing nuts are initially tightened, and the verticality of the center column is measured by a measuring tool. The verticality of the center column is adjusted by the elevation positioning nuts. After the verticality of the center column is measured, the fixing nuts are finally tightened, and the installation of the center column is completed. When adjusting the verticality of the center column, the verticality of the center column needs to be adjusted by the elevation positioning nuts. Due to the heavy weight of the center column, it is difficult to adjust, which is time-consuming and labor-intensive, and reduces the installation efficiency of the steel structure.

[0006] Therefore, a new solution needs to be proposed to solve this problem. Utility Model Content

[0007] The technical problem to be solved by the utility model is to provide a soil sampler, which solves the problem of difficulty in adjusting the verticality in the installation of the center column in the prior art.

[0008] The technical problem to be solved by the utility model is achieved by adopting the following technical solutions:

[0009] An auxiliary tool for installing a center column base plate in steel structure manufacturing comprises a center column and a base plate arranged at the bottom end of the center column, wherein a plurality of anchor bolts are evenly penetrated on the base plate along the circumference of the center column, the bottom ends of the anchor bolts are pre-buried in a cement matrix, an elevation positioning nut is threadedly connected to the anchor bolt below the base plate, a fastening nut is threadedly connected to the anchor bolt above the base plate, a verticality adjustment device is arranged around the center column on the upper end surface of the base plate, the verticality adjustment device is used to adjust the verticality of the center column, the verticality adjustment device comprises a main adjustment plate and an auxiliary adjustment plate which are detachably connected, a heightening base is arranged between the cement matrix and the main adjustment plate and the auxiliary adjustment plate, and the bottom surfaces of the main adjustment plate and the auxiliary adjustment plate are fixed to the heightening base.

[0010] The utility model is further configured such that two threaded rods are vertically penetrated inward from two side surfaces of the main adjustment plate, the two threaded rods are threadedly connected to the main adjustment plate, and the inner end of each threaded rod abuts against the corresponding adjacent surface of the center column.

[0011] The utility model is further configured such that two accommodating holes are provided inside the auxiliary adjustment plate, and push rods are slidably arranged inside the two accommodating holes. Springs are arranged at the outer ends of the push rods, and the outer ends of the springs are fixed to the inner top walls of the accommodating holes. The inner ends of each push rod abut against the corresponding adjacent surfaces of the center column.

[0012] The utility model is further configured that the main adjustment plate and the auxiliary adjustment plate are fixed to the heightened base through expansion bolts.

[0013] The utility model is further configured such that sleeves are provided in the two accommodating holes of the auxiliary adjustment plate, each push rod is inserted into the corresponding sleeve, and each push rod is fixed to the inner top wall of the sleeve by a spring.

[0014] The utility model is further configured such that a slider having a diameter larger than that of the push rod is provided at the outer end of each push rod, the slider is slidably connected to the inner wall of the sleeve, a through hole matching the diameter of the push rod is formed on the inner wall of the inner end of the sleeve, and the outer end of each slider is fixed to a spring.

[0015] The utility model is further configured such that the outer side surfaces of the joints of the main adjustment plate and the auxiliary adjustment plate are respectively provided with a first docking block and a second docking block, each first docking block is provided with a threaded hole, and each second docking block is provided with a through hole, and a fixing bolt is inserted from the through hole of the second docking block and threadedly connected with the corresponding threaded hole of the first docking block to fix the corresponding first docking block to the second docking block.

[0016] The utility model is further configured that each top rod and the inner end of each threaded rod are rotatably connected with a top plate, and a side surface close to each top plate is in conflict with the symmetrical inclined surface of the center column.

[0017] The beneficial effects of the utility model are:

[0018] When the utility model is in use, after the bottom plate of the middle column is placed, the main adjusting plate and the auxiliary adjusting plate are first connected together around the middle column, so that the top plate and the four surfaces of the middle column are respectively in conflict with each other, and then the main adjusting plate and the auxiliary adjusting plate are fixed to the heightened matrix or the cement matrix by expansion bolts, and then the verticality of the middle column is measured by a measuring tool, and the threaded rod is rotated to extend or shorten the threaded rod to adjust the verticality of the middle column. After the verticality is adjusted, each elevation positioning nut is first rotated so that the elevation positioning nuts are in conflict with the bottom surface of the top plate, and then the fastening nut is tightened to complete the installation, thereby achieving the purpose of effectively and quickly adjusting the verticality of the middle column.

[0019] The utility model is provided with a center column, a first docking block, a second docking block, a main adjustment plate, and an auxiliary adjustment plate. When the device is used, when the verticality of the center column needs to be adjusted, the main adjustment plate and the auxiliary adjustment plate are docked together, the center column is surrounded in the middle, and each top plate is respectively in contact with the four side surfaces of the center column, and then bolts are passed through the through holes of the second docking block and are threadedly connected with the threaded holes corresponding to the first docking block, so that the corresponding first docking block and the corresponding second docking block are fixed together, and then the main adjustment plate and the auxiliary adjustment plate are fixed together, so as to achieve the purpose of detachable connection between the main adjustment plate and the auxiliary adjustment plate. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a schematic diagram of the overall three-dimensional structure of the utility model;

[0021] Figure 2 This is a schematic diagram of the front view structure of the utility model;

[0022] Figure 3 This is a schematic diagram of the internal three-dimensional structure of the auxiliary adjustment plate of the utility model;

[0023] Figure 4 This is a schematic diagram of the internal top view of the auxiliary adjustment plate of the utility model;

[0024] Figure 5 This is a schematic diagram of the three-dimensional structure of the anchor bolt of the utility model;

[0025] Figure 6 This is a schematic diagram of the structure of the utility model after the base plate and the base are installed;

[0026] Figure 7 For this utility model Figure 3 A schematic diagram of the structure enlargement at point A;

[0027] Figure 8 For this utility model Figure 6 Enlarged schematic diagram of the structure at point B in the middle.

[0028] In the figure: 1. center column; 2. bottom plate; 3. cement matrix; 4. heightening matrix; 5. main adjustment plate; 6. threaded rod; 7. auxiliary adjustment plate; 8. casing; 9. push rod; 10. slider; 11. spring; 12. first docking block; 13. second docking block; 14. fixing bolt; 15. top plate; 16. expansion bolt; 17. fastening nut; 18. anchor bolt; 19. elevation positioning nut. DETAILED DESCRIPTION

[0029] In order to make the technical means, creative features, objectives and effects of the present invention easier to understand, the present invention is further described below in conjunction with specific illustrations.

[0030] like Figure 1 - Figure 8The auxiliary tool for installing the bottom plate of a center column in a steel structure comprises a center column 1 and a bottom plate 2 arranged at the bottom end of the center column 1. A plurality of anchor bolts 18 are evenly penetrated on the bottom plate 2 along the circumference of the center column 1. The bottom ends of the anchor bolts 18 are pre-buried in a cement matrix 3. The anchor bolts 18 are threadedly connected with elevation positioning nuts 19 located below the bottom plate 2. The anchor bolts 18 are threadedly connected with fastening nuts 17 located above the bottom plate 2. A verticality adjustment device is arranged around the center column 1 on the upper end surface of the bottom plate 2. The verticality adjustment device is used to adjust the verticality of the center column 1. The verticality adjustment device comprises a detachably connected The main adjustment plate 5 and the auxiliary adjustment plate 7, a heightening base 4 is arranged between the cement base 3 and the main adjustment plate 5 and the auxiliary adjustment plate 7, the bottom surfaces of the main adjustment plate 5 and the auxiliary adjustment plate 7 are fixed to the heightening base 4, when in use, firstly, a number of anchor bolts 18 are embedded in the cement base 3, and then a heightening base 4 is made around the middle column 1 on the cement base 3, the heightening base 4 semi-surrounds the middle column 1, the heightening base 4 is made of cement, and then an elevation positioning nut 19 is screwed on each anchor bolt 18, and the height of each elevation positioning nut 19 is measured by a level measuring instrument to make them consistent, and then the middle column 1 is passed through the starting The lifting device is lifted and moved to the top of the anchor bolt 18, and the personnel straighten the middle column 1 on site, and slowly lower the middle column 1 so that the anchor bolt 18 is inserted into the mounting hole of the bottom plate 2, and then the main adjustment plate 5 and the auxiliary adjustment plate 7 are connected together, and the middle column 1 passes between the main adjustment plate 5 and the auxiliary adjustment plate 7, and then the main adjustment plate 5 and the auxiliary adjustment plate 7 are respectively fixed to the heightening base 4. At this time, the surveyor measures the verticality of the middle column 1 through the measuring instrument, and adjusts the verticality of the middle column 1 through the main adjustment plate 5 and the auxiliary adjustment plate 7 according to the measurement results, until the verticality measurement result of the middle column 1 meets the requirements. The set value is met, and then each elevation positioning nut 19 is screwed upwards so that each elevation positioning nut 19 is in contact with the bottom surface of the base plate 2. Then, the fastening nut 17 is screwed on the top of each anchor bolt 18 so that the fastening nut 17 presses the base plate 2. The installation of the middle column 1 and the base plate 2 is completed. The main adjustment plate 5 and the auxiliary adjustment plate 7 can be removed. Then, the heightening base 4 is made of cement again, so that the heightening base 4 completely surrounds the middle column 1. Subsequently, cement is filled in the interior of the heightening base 4 for pouring, so that a part of the length of the bottom of the middle column 1 is buried in the heightening base 4, ensuring that the installation of the middle column 1 is stable.

[0031] In order to achieve the purpose of adjusting the verticality of the center column 1 through the main adjustment plate 5, in the utility model, two threaded rods 6 are vertically penetrated inward from the two side surfaces of the main adjustment plate 5, and the two threaded rods 6 are threadedly connected to the main adjustment plate 5. The inner end of each threaded rod 6 is in contact with the corresponding adjacent surface of the center column 1. When the verticality of the center column 1 is measured and the verticality of the center column 1 needs to be positively adjusted according to the measured data, the threaded rod 6 is rotated to extend inward relative to the main adjustment plate 5, so that the threaded rod 6 pushes the center column 1 when extending inward, so that the verticality of the center column 1 changes, thereby achieving the purpose of positive adjustment of the verticality of the center column 1.

[0032] In order to be able to assist the main adjustment plate 5 with the auxiliary adjustment plate 7 to more flexibly adjust the verticality of the center column 1 and realize the negative adjustment of the verticality of the center column 1, in this embodiment, two accommodating holes are opened inside the auxiliary adjustment plate 7, and push rods 9 are slidably arranged inside the two accommodating holes. The outer ends of the push rods 9 are provided with springs 11. The outer ends of the springs 11 are fixed to the inner top walls of the accommodating holes. The inner ends of each push rod 9 are in contact with the corresponding adjacent surfaces of the center column 1. When the main adjustment plate 5 and the auxiliary adjustment plate 7 are connected together around the center column 1 and installed and fixed on the heightening base 4, the measurement personnel use the measuring tool to align the center column 1. The verticality of the column 1 is measured. When the verticality of the center column 1 needs to be positively adjusted according to the measurement data, the threaded rod 6 is rotated to extend inward, pushing the center column 1, so that the verticality of the center column 1 changes, and the verticality of the center column 1 is adjusted; when the verticality of the center column 1 needs to be negatively adjusted according to the measurement data, the threaded rod 6 is rotated to extend outward, the inner end of the threaded rod 6 is away from the center column 1, and the corresponding push rod 9 is pushed out by the spring 11, so that the verticality of the center column 1 changes, and the purpose of negative adjustment of the verticality of the center column 1 is achieved.

[0033] In order to make the inner ends of the threaded rod 6 and the inner ends of the push rod 9 better contact with the side of the center column 1 and push the center column 1 more effectively, thereby realizing the positive and negative adjustment of the verticality of the center column 1, in this embodiment, each push rod 9 and the inner ends of each threaded rod 6 are rotatably connected to the top plate 15, and the side surfaces close to each top plate 15 are in conflict with the symmetrical inclined surfaces of the center column 1. Rotating the threaded rod 6 causes the threaded rod 6 to move inward, and the inner ends of the threaded rod 6 push the center column 1 through the top plate 15. Since the top plate 15 increases the contact area of ​​the threaded rod 6 on the side of the center column 1, the threaded rod 6 pushes the center column 1 more effectively through the top plate 15. Similarly, when the threaded rod 6 rotates and moves outward, the corresponding push rod 9 is pushed inward under the action of the spring 11, so that the push rod 9 drives the corresponding top plate 15 to push the center column 1, and the push rod 9 pushes the center column 1 more effectively through the top plate 15.

[0034] In order to facilitate the later disassembly, assembly and maintenance of the push rod 9 and the spring 11, in the present embodiment, a sleeve 8 is provided in the two accommodating holes of the auxiliary adjustment plate 7, each push rod 9 is inserted into the corresponding sleeve 8, and each push rod 9 is fixed to the inner top wall of the sleeve 8 by the spring 11. By fixing the sleeve 8 in the accommodating hole of the auxiliary adjustment plate 7 and allowing the push rod 9 to slide inside the sleeve 8, the push rod 9 is able to extend inward under the action of the spring 11. At the same time, during use, if the push rod 9 is damaged, such as worn, bent or the fatigue degree of the spring 11 does not meet the set standard, the sleeve 8 can be removed and the push rod 9 or the spring 11 can be replaced, which is convenient for later maintenance.

[0035] In order to realize the limiting function when the push rod 9 is ejected toward the inner end, in this embodiment, a slider 10 with a diameter larger than that of the push rod 9 is provided at the outer end of each push rod 9, and the slider 10 is slidably connected to the inner wall of the sleeve 8, and a through hole matched with the diameter of the push rod 9 is formed at the inner wall of the inner end of the sleeve 8. The outer end of each slider 10 is fixed to the spring 11. When the push rod 9 is ejected toward the inner end, the spring 11 pushes the slider 10 to move, and the slider 10 pushes the push rod 9 to move toward the inner end. When the slider 10 moves to the through hole at the inner end of the sleeve 8, due to the small inner diameter of the through hole, the continued movement of the slider 10 is limited, thereby limiting the continued movement of the push rod 9 toward the inner end.

[0036] In order to fix the main adjustment plate 5 and the auxiliary adjustment plate 7 to the heightened base 4 for easy installation and disassembly, in the present embodiment, the main adjustment plate 5 and the auxiliary adjustment plate 7 are fixed to the heightened base 4 by expansion bolts 16. When the main adjustment plate 5 and the auxiliary adjustment plate 7 need to be fixed to the heightened base 4 respectively, first, holes are drilled on the upper end surface of the heightened base 4 by a drilling device, and then the main adjustment plate 5 and the auxiliary adjustment plate 7 are fixed to the heightened base 4 by the expansion bolts 16 for easy installation and disassembly.

[0037] In order to facilitate the connection between the main adjustment plate 5 and the auxiliary adjustment plate 7, in this embodiment, the outer side surfaces of the joints of the main adjustment plate 5 and the auxiliary adjustment plate 7 are respectively provided with a first docking block 12 and a second docking block 13, each of which is provided with a threaded hole, and each of which is provided with a through hole, and a fixing bolt 14 is inserted from the through hole of the second docking block 13 and threadedly connected with the corresponding threaded hole of the first docking block 12, so that the corresponding first docking block 12 is fixed to the second docking block 13, and the second docking block 13 and the first docking block 12 can be conveniently fixed together by the fixing bolt 14, thereby conveniently fixing the main adjustment plate 5 and the auxiliary adjustment plate 7 together, and facilitating disassembly and installation.

[0038] The implementation principle of the utility model is as follows: first, a foundation bolt 18 is embedded in the cement matrix 3, and then a heightening matrix 4 is made around the middle column 1 on the cement matrix 3, and the heightening matrix 4 semi-surrounds the middle column 1, and the heightening matrix 4 is made of cement, and then a height positioning nut 19 is screwed on each foundation bolt 18, and the height of each elevation positioning nut 19 is measured by a level measuring instrument to make them consistent, and then the middle column 1 is lifted and moved to the top of the foundation bolt 18 by a lifting device, and the middle column 1 is straightened on site by personnel, and the middle column 1 is slowly lowered so that the foundation bolt 18 is inserted into the mounting hole of the bottom plate 2, and then the main adjustment plate 5 and the auxiliary adjustment plate 7 are fixedly connected together by the fixing bolts 14, and the middle column 1 is passed between the main adjustment plate 5 and the auxiliary adjustment plate 7, and then the main adjustment plate 5 and the auxiliary adjustment plate 7 are respectively fixedly connected to the heightening matrix 4 by expansion bolts 16 At this time, the surveyor measures the verticality of the center column 1 through the measuring instrument, and adjusts the verticality of the center column 1 positively or negatively through the main adjustment plate 5 and the auxiliary adjustment plate 7 according to the measurement result. The specific operation is achieved by rotating the threaded rod 6 until the verticality measurement result of the center column 1 meets the set value, and then each elevation positioning nut 19 is screwed upward so that each elevation positioning nut 19 is in conflict with the bottom surface of the base plate 2, and then the fastening nut 17 is screwed on the top of each anchor bolt 18 so that the fastening nut 17 presses the base plate 2. The installation of the center column 1 and the base plate 2 is completed, and the main adjustment plate 5 and the auxiliary adjustment plate 7 can be removed, and then the heightening base 4 is made of cement again, so that the heightening base 4 completely surrounds the center column 1, and then the cement is filled in the interior of the heightening base 4 for pouring, so that a part of the length of the bottom of the center column 1 is buried in the heightening base 4, ensuring the stable installation of the center column 1.

[0039] The above shows and describes the basic principles, main features and advantages of the utility model. Those skilled in the art should understand that the utility model is not limited to the above embodiments. Without departing from the spirit and scope of the utility model, the utility model may have various changes and improvements, which fall within the scope of protection claimed by the utility model. The scope of protection claimed by the utility model is defined by the attached claims and their equivalents.

Claims

1. An auxiliary tool for installing a center column base plate in a steel structure, comprising a center column (1) and a base plate (2) arranged at the bottom end of the center column (1), characterized in that: A plurality of anchor bolts (18) are evenly arranged on the base plate (2) along the circumference of the center column (1), the bottom ends of the anchor bolts (18) are pre-buried in the cement matrix (3), the anchor bolts (18) are threadedly connected with elevation positioning nuts (19) located below the base plate (2), and the anchor bolts (18) are threadedly connected with fastening nuts (17) located above the base plate (2), and a verticality adjustment device is arranged around the center column (1) on the upper end surface of the base plate (2), and the verticality adjustment device is used to adjust the verticality of the center column (1), and the verticality adjustment device includes a main adjustment plate (5) and an auxiliary adjustment plate (7) that are detachably connected, and a heightening base (4) is arranged between the cement matrix (3) and the main adjustment plate (5) and the auxiliary adjustment plate (7), and the bottom surfaces of the main adjustment plate (5) and the auxiliary adjustment plate (7) are fixedly arranged with the heightening base (4).

2. The auxiliary tool for installing the bottom plate of a center column in steel structure manufacturing according to claim 1 is characterized in that: Two threaded rods (6) are vertically penetrated from the two side surfaces of the main adjustment plate (5) inwardly, and the two threaded rods (6) are threadedly connected to the main adjustment plate (5), and the inner end of each threaded rod (6) contacts the corresponding adjacent surface of the center column (1).

3. The auxiliary tool for installing the bottom plate of a center column in steel structure manufacturing according to claim 2 is characterized in that: Two receiving holes are provided inside the auxiliary adjustment plate (7), and push rods (9) are slidably arranged inside the two receiving holes. A spring (11) is arranged at the outer end of the push rod (9), and the outer end of the spring (11) is fixed to the inner top wall of the receiving hole. The inner end of each push rod (9) contacts the corresponding adjacent surface of the central column (1).

4. The auxiliary tool for installing the bottom plate of a center column in steel structure manufacturing according to claim 3 is characterized in that: The main adjustment plate (5) and the auxiliary adjustment plate (7) are fixed to the heightened base (4) via expansion bolts (16).

5. The auxiliary tool for installing the bottom plate of a center column in steel structure manufacturing according to claim 3 is characterized in that: A sleeve (8) is provided in each of the two receiving holes of the auxiliary adjustment plate (7), each push rod (9) is inserted into the corresponding sleeve (8), and each push rod (9) is fixed to the inner top wall of the sleeve (8) via a spring (11).

6. The auxiliary tool for installing the bottom plate of a center column in steel structure manufacturing according to claim 5, characterized in that: The outer end of each push rod (9) is provided with a slider (10) having a diameter larger than that of the push rod (9); the slider (10) is slidably connected to the inner wall of the sleeve (8); a through hole matching the diameter of the push rod (9) is formed on the inner wall of the inner end of the sleeve (8); and the outer end of each slider (10) is fixed to a spring (11).

7. The auxiliary tool for installing the bottom plate of a center column in steel structure manufacturing according to claim 1, characterized in that: A first docking block (12) and a second docking block (13) are respectively arranged on the outer side surfaces of the joints of the main adjustment plate (5) and the auxiliary adjustment plate (7), each first docking block (12) is provided with a threaded hole, and each second docking block (13) is provided with a through hole, and a fixing bolt (14) is inserted from the through hole of the second docking block (13) and threadedly connected with the threaded hole of the corresponding first docking block (12), so that the corresponding first docking block (12) is fixed to the second docking block (13).

8. The auxiliary tool for installing the bottom plate of a center column in steel structure manufacturing according to claim 3 is characterized in that: The inner ends of each top rod (9) and each threaded rod (6) are rotatably connected to a top plate (15), and a side surface close to each top plate (15) contacts the symmetrical inclined surface of the center column (1).

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