A steel cable guiding device for a tower crane

Abstract

The invention discloses a steel cable guiding device for a tower crane, which relates to the technical field of construction equipment, and comprises a connecting rod connected to the tower crane, wherein two connecting rods are provided, and a connecting block is fixedly provided between opposite sides of the two connecting rods, and the steel cable guiding device of the tower crane also comprises an adjusting plate and an adjusting roller for adjusting the tension of the steel cable, and the adjusting roller is located below the adjusting plate; the steel cable guiding device of the tower crane can roughly and preliminarily adjust the tension of the steel cable through the matching arrangement of the adjusting plate and a control member, and after the partial adjustment is completed, the adjusting roller is driven to rotate by driving the adjusting member, and the adjusting roller can push the steel cable passing around its surface to bend, so as to further adjust the tension of the steel cable; the invention uses the synergistic effect of the adjusting plate and the adjusting roller to further adjust the tension of the steel cable after the preliminary adjustment of the tension of the steel cable is achieved, thereby effectively improving the adjustment accuracy of the steel cable, thereby ensuring the stability of the tower crane and the safety of operation.

Description

Technical Field

[0001] The invention relates to the technical field of construction equipment, and in particular to a steel cable guiding device of a tower crane. Background Art

[0002] Tower crane, also known as tower crane, originated in Western Europe. It is a rotating crane with a boom mounted on the top of a tall tower. It has a large working space and is mainly used for vertical and horizontal transportation of materials and installation of building components in house construction. It consists of three parts: metal structure, working mechanism and electrical system. The cable guide device is an important component of the tower crane.

[0003] A Chinese invention patent with publication number CN105217491A discloses a steel cable guiding device for a tower crane, which comprises a fixed pivot, a V-shaped guiding bracket is provided at the tail of the fixed pivot, and a rotatable guiding column head is provided at each end of the guiding bracket. The steel cable guiding device for a tower crane of the present invention utilizes a pair of guiding columns made of tungsten steel in the guiding bracket, which can effectively support and guide the steel cable, completely solve the twisting and knotting of the steel cable, and greatly improve the smoothness and safety of the tower crane steel cable transmission. The steel cable guiding device for a tower crane has a simple structure, is easy to install, and is highly practical.

[0004] The existing tower crane steel cable guiding device cannot adjust the tension of the steel cable when in use, which easily causes the steel cable to become loose or over-tightened when bearing weight, thereby failing to ensure the stability of the tower crane and the safety of operation; and inappropriate tension may lead to serious consequences such as steel cable breakage or overturning of the tower crane; therefore, the present invention proposes a tower crane steel cable guiding device to solve the above problems. Summary of the invention

[0005] The object of the present invention is to provide a steel cable guiding device for a tower crane to solve the above-mentioned deficiencies in the prior art.

[0006] In order to achieve the above-mentioned object, the present invention provides the following technical solutions: a steel cable guiding device for a tower crane, comprising a connecting rod connected to the tower crane, wherein two connecting rods are provided, and a connecting block is fixedly provided between opposite sides of the two connecting rods, and the steel cable guiding device for the tower crane also comprises an adjusting plate and an adjusting roller for adjusting the tension of the steel cable, wherein the adjusting roller is located below the adjusting plate;

[0007] An adjustment hole is formed inside the connecting block, a stabilizing rod is rotatably arranged inside the adjustment hole, an adjustment rod is symmetrically fixedly arranged on the outer surface of the stabilizing rod, and the adjustment roller is rotatably arranged between the ends of the two adjustment rods;

[0008] The connecting block is symmetrically fixed with a mounting block, the adjusting plate is provided with a plurality of adjusting plates evenly distributed on the circumferential surface of the mounting block, the mounting block is provided with a control member for adjusting the distance between the adjusting plate and the surface of the mounting block, and the connecting block is provided with a driving adjusting control member for adjusting and locking the position of the adjusting roller;

[0009] The control member comprises a control rod 1 which is rotatably connected to the adjustment plate at one end, a control rod 2 which is rotatably arranged at the other end of the control rod 1, and an end of the control rod 2 which is away from the control rod 1 and is rotatably arranged at the mounting block;

[0010] The driving adjustment control unit includes a driving block located above the connecting block, on the inner wall of the driving block are slidingly arranged an adjustment block 1 and an adjustment block 2 which are staggered in distribution, a driving member is fixedly arranged inside the connecting block, and the output end of the driving member passes through the connecting block and is fixedly arranged with the driving block.

[0011] As a further optimization solution of the present invention, the adjustment plate is designed to be arc-shaped, and a spiral groove for placing and limiting the steel cable is provided on its outer surface.

[0012] As a further optimization scheme of the present invention, stabilizing blocks are fixedly arranged on opposite sides of the two mounting blocks, a guide groove is penetrated through the stabilizing blocks, and the second control rod penetrates the guide groove and is arranged in contact with the inner surface thereof.

[0013] As a further optimization scheme of the present invention, a bidirectional telescopic member is fixedly arranged between opposite sides of the two stabilizing blocks, a control disc is fixedly arranged at the output end of the bidirectional telescopic member, and the end of the second control rod is rotatably arranged with the outer surface of the control disc.

[0014] As a further optimization solution of the present invention, one side of the control rod 1 extends outward to form a connecting protrusion, and the connecting protrusion is rotatably arranged with the outer surface of the stabilizing block.

[0015] As a further optimization scheme of the present invention, the interior of the driving block is symmetrically provided with an adjustment groove 1 and an adjustment groove 2, the adjustment block 1 is slidably set inside the adjustment groove 1, and the adjustment block 2 is slidably set inside the adjustment groove 2, wherein the end of the adjustment roller extends to the interior of the adjustment groove 2 and fits with the top of the adjustment block 2.

[0016] As a further optimization scheme of the present invention, a locking elastic member 1 is fixedly arranged between the regulating block 1 and the inner top wall of the regulating groove 1, and a locking elastic member 2 is fixedly arranged between the regulating block 2 and the inner bottom wall of the regulating groove 2.

[0017] As a further optimization solution of the present invention, both upper and lower sides of the opposite sides of the regulating block 1 and the regulating block 2 are inclined surfaces.

[0018] Compared with the prior art, the steel cable guiding device for a tower crane provided by the present invention has the following beneficial effects: through the coordinated arrangement of the adjusting plate and the control part, the tension of the steel cable can be roughly and initially adjusted. After the adjustment is completed, the adjusting roller is driven to rotate by driving the adjusting control part, and the adjusting roller can push the steel cable passing around its surface to bend, thereby further adjusting the tension of the steel cable; the present invention, through the coordinated action of the adjusting plate and the adjusting roller, can further adjust the tension of the steel cable after the preliminary adjustment is achieved, thereby effectively improving the adjustment accuracy of the steel cable, thereby ensuring the stability of the tower crane and the safety of operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For ordinary technicians in this field, other drawings can also be obtained based on these drawings.

[0020] Figure 1 A schematic diagram of the overall structure provided by an embodiment of the present invention;

[0021] Figure 2 A schematic cross-sectional view of the overall structure provided by an embodiment of the present invention;

[0022] Figure 3 A schematic diagram of the connection between the control element and the adjustment plate provided in an embodiment of the present invention;

[0023] Figure 4 A cross-sectional schematic diagram of a control member and an adjustment plate provided in an embodiment of the present invention;

[0024] Figure 5 A vertical cross-sectional schematic diagram of a control member and an adjustment plate provided in an embodiment of the present invention;

[0025] Figure 6 A schematic diagram of a drive adjustment control unit provided by an embodiment of the present invention;

[0026] Figure 7 A horizontal vertical cross-sectional schematic diagram of a drive adjustment control unit provided by an embodiment of the present invention;

[0027] Figure 8 A schematic longitudinal section diagram of a drive adjustment control unit provided by an embodiment of the present invention;

[0028] Fig. 9 The embodiment of the present invention provides Figure 8 Enlarged schematic diagram at point A in the middle.

[0029] Description of reference numerals:

[0030] 1. Connecting rod; 2. Connecting block; 201. Adjusting hole; 3. Adjusting plate; 4. Adjusting roller; 401. Stabilizing rod; 402. Adjusting rod; 5. Mounting block; 6. Control member; 601. Control rod one; 6011. Connecting protrusion; 602. Control rod two; 603. Two-way telescopic member; 604. Control disc; 7. Drive adjusting component; 701. Drive block; 702. Control block one; 703. Control block two; 704. Drive member; 705. Control slot one; 706. Control slot two; 707. Locking elastic member one; 708. Locking elastic member two; 8. Stabilizing block; 9. Guide slot. DETAILED DESCRIPTION

[0031] In order to enable those skilled in the art to better understand the technical solution of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings.

[0032] Embodiment 1

[0033] See also Figure 1-Figure 9 A steel cable guiding device for a tower crane includes a connecting rod 1 connected to the tower crane, two connecting rods 1 are provided, and a connecting block 2 is fixedly provided between opposite sides of the two connecting rods 1, the connecting block 2 is designed in a "U" shape, and its two side walls are fixedly connected to the side of the connecting rod 1. The steel cable guiding device for the tower crane also includes an adjusting plate 3 and an adjusting roller 4 for adjusting the tension of the steel cable, and the adjusting roller 4 is located below the adjusting plate 3;

[0034] For this explanation, the adjustment plate 3 is designed to be arc-shaped, and its outer surface is provided with a spiral groove for limiting the placement of the steel cable. Through the setting of the spiral groove, when the steel cable is partially wound around the outer surface of the adjustment plate 3, its position will not move, thereby improving the stability of the steel cable during use and preventing the steel cable from being entangled.

[0035] An adjustment hole 201 is formed through the interior of the connecting block 2, a stabilizing rod 401 is rotatably provided inside the adjustment hole 201, and an adjustment rod 402 is symmetrically fixedly provided on the outer surface of the stabilizing rod 401. The stabilizing rod 401 provides support for the adjustment rod 402, thereby improving the stability of the adjustment rod 402 during rotation; the adjustment roller 4 is rotatably provided between the ends of the two adjustment rods 402.

[0036] The connection block 2 is symmetrically fixed with mounting blocks 5, which are used to support the entire drive adjustment control unit 7; the adjustment plate 3 is provided with multiple and evenly distributed on the circumferential surface of the mounting block 5, and the mounting block 5 is provided with a control member 6 for adjusting the distance between the adjustment plate 3 and the surface of the mounting block 5, and the connection block 2 is provided with a drive adjustment control unit 7 for adjusting and locking the position of the adjustment roller 4. The adjustment plate 3 is driven by the control member 6 to drive the multiple adjustment plates 3 to move, thereby changing the diameter of the circle surrounded by the adjustment plates 3 to achieve the adjustment of the cable tension; the adjustment roller 4 is driven to rotate, thereby further adjusting the cable tension and improving the adjustment accuracy, and the position of the adjustment roller 4 can be locked synchronously to improve the overall stability of the device when in use.

[0037] Among them, regarding the design scheme of the control member 6, the control member 6 includes a control rod 601 with one end rotatably connected to the adjustment plate 3, and the other end of the control rod 601 is rotatably provided with a control rod 602, and the end of the control rod 602 away from the control rod 601 is rotatably provided with the mounting block 5.

[0038] Preferably, a stabilizing block 8 is fixedly provided on opposite sides of the two mounting blocks 5, a guide groove 9 is penetrated through the stabilizing block 8, and the second control rod 602 penetrates the guide groove 9 and is arranged in contact with the inner surface thereof, thereby providing support and limiting effect to the second control rod 602; one side of the control rod 1 601 extends outward to form a connecting protrusion 6011, and the connecting protrusion 6011 is rotatably arranged with the outer surface of the stabilizing block 8. By setting the connecting protrusion 6011, the control rod 1 601 is supported and limited, so that the control rod 1 601 can rotate around the connection between the connecting protrusion 6011 and the stabilizing block 8.

[0039] For this explanation, a bidirectional telescopic member 603 is fixedly arranged between the opposite sides of the two stabilizing blocks 8. The bidirectional telescopic member 603 is a bidirectional electric push rod, and its oil inlet is connected to the oil outlet of the external oil pump; a plurality of support rods are fixedly arranged between the opposite sides of the two stabilizing blocks 8, and the support rods are misaligned with the control rod 1 601. A support plate is fixedly arranged between the plurality of support rods, and the bidirectional telescopic member 603 is fixedly arranged on the support plate through and through, so that when the bidirectional telescopic member 603 is in operation, the control discs 604 at both ends can be driven to move synchronously, ensuring that the movement distance and movement speed are the same. The output ends of the bidirectional telescopic member 603 are fixedly arranged with the control disc 604, and the end of the control rod 2 602 is rotatably arranged with the outer surface of the control disc 604.

[0040] By starting the output end of the two-way telescopic member 603 to extend outward, the control discs 604 at both ends thereof are driven to move in the opposite direction. The control disc 604 pushes the control rod 1 601 to rotate around the connection between the connecting protrusion 6011 and the stabilizing block 8 through the control rod 2 602. At this time, the control rod 2 602 pushes the adjustment plate 3 to move to the side away from the two-way telescopic member 603, so that the diameter of the circle formed by the multiple adjustment plates 3 is increased, thereby realizing the adjustment of the tension of the steel cable.

[0041] Among them, regarding the design scheme of the driving adjustment control unit 7, the driving adjustment control unit 7 includes a driving block 701 located above the connecting block 2, and the inner wall of the driving block 701 is slidably provided with a staggered distribution of the adjustment block 1 702 and the adjustment block 2 703, and the connection block 2 is fixedly provided with a driving member 704 inside, and the driving member 704 is a hydraulic rod, and its oil inlet is connected to the oil outlet of the external oil pump; the output end of the driving member 704 passes through the connecting block 2 and is fixedly provided with the driving block 701. By controlling the output end of the driving member 704, the driving block 701 is driven to move in the vertical direction.

[0042] For this purpose, the interior of the driving block 701 is symmetrically provided with an adjusting groove 1 705 and an adjusting groove 2 706, and the opposite side portions of the adjusting groove 1 705 and the adjusting groove 2 706 are connected, so that the adjusting roller 4 can switch between the positions of the adjusting groove 1 705 and the adjusting groove 2 706, and the height of the adjusting groove 2 706 is lower than the height of the adjusting groove 1 705; the adjusting block 1 702 is slidably arranged inside the adjusting groove 1 705, and the adjusting block 2 703 is slidably arranged inside the adjusting groove 2 706, wherein the end of the adjusting roller 4 extends to the interior of the adjusting groove 2 706 and fits with the top of the adjusting block 2 703.

[0043] Preferably, the upper and lower sides of the opposite sides of the regulating block 1 702 and the regulating block 2 703 are both inclined surfaces; a locking elastic member 1 707 is fixedly arranged between the regulating block 1 702 and the inner top wall of the regulating groove 1 705, and a locking elastic member 2 708 is fixedly arranged between the regulating block 2 703 and the inner bottom wall of the regulating groove 2 706.

[0044] For illustration, both the locking elastic member 1 707 and the locking elastic member 2 708 are springs, and their elastic coefficients can be set according to requirements.

[0045] When the locking elastic member 1 707 and the locking elastic member 2 708 are only affected by the gravity of the regulating block 1 702 and the regulating block 2 703 and are not affected by other external forces, the opposite side parts of the regulating block 1 702 and the regulating block 2 703 are partially fitted together. At this time, the end of the adjusting roller 4 is limited between the regulating block 2 703 and the inner top wall of the regulating groove 2 706, and fits with the connection between the plane and the inclined surface on the regulating block 1 702, and the side surface of the adjusting roller 4 fits with the connection between the vertical surface and the inclined surface of the regulating block 1 702.

[0046] When the output end of the driving member 704 extends upward, it drives the driving block 701 to move upward synchronously, and the driving block 701 drives the regulating block 1 702 and the regulating block 2 703 to move upward. At this time, since the adjusting roller 4 is limited by the regulating block 1 702 and the regulating block 2 703, the adjusting rod 402 cannot rotate. Under the reverse force of the adjusting roller 4, the regulating block 2 703 is limited, and the locking elastic member 2 708 is compressed, so that the regulating block 1 702 and the regulating block 2 703 are gradually misaligned. The driving member 704 continues to drive. At this time, under the action of the inclined plane, the adjusting roller 4 moves along the inclined planes on the regulating block 1 702 and the regulating block 2 703, moves from the regulating groove 2 706 to the inside of the regulating groove 1 705, and is located at the bottom of the regulating block 1 702. When the adjusting roller 4 moves, it drives the adjusting rod 402 to rotate around the axis of the stabilizing rod 401, thereby further fine-tuning the tension of the steel cable and improving the adjustment accuracy.

[0047] Preferably, the inner wall of the adjustment hole 201 and the outer surface of the adjustment rod 402 are both rotatably provided with a connecting shaft, and a connecting spring is fixedly provided between the two connecting shafts, so that when the position of the adjustment roller 4 changes, the state of the connecting spring is changed, and its elastic force is applied to the adjustment rod 402, thereby ensuring the stability of the position of the adjustment roller 4 after movement.

[0048] Embodiment 2

[0049] See also Figure 1-Figure 9 A steel cable guiding device for a tower crane includes a connecting rod 1 connected to the tower crane, two connecting rods 1 are provided, and a connecting block 2 is fixedly provided between opposite sides of the two connecting rods 1, the connecting block 2 is designed in a "U" shape, and its two side walls are fixedly connected to the side of the connecting rod 1. The steel cable guiding device for the tower crane also includes an adjusting plate 3 and an adjusting roller 4 for adjusting the tension of the steel cable, and the adjusting roller 4 is located below the adjusting plate 3;

[0050] For this explanation, the adjustment plate 3 is designed to be arc-shaped, and its outer surface is provided with a spiral groove for limiting the placement of the steel cable. Through the setting of the spiral groove, when the steel cable is partially wound around the outer surface of the adjustment plate 3, its position will not move, thereby improving the stability of the steel cable during use and preventing the steel cable from being entangled.

[0051] An adjustment hole 201 is formed through the interior of the connecting block 2, a stabilizing rod 401 is rotatably provided inside the adjustment hole 201, and an adjustment rod 402 is symmetrically fixedly provided on the outer surface of the stabilizing rod 401. The stabilizing rod 401 provides support for the adjustment rod 402, thereby improving the stability of the adjustment rod 402 during rotation; the adjustment roller 4 is rotatably provided between the ends of the two adjustment rods 402.

[0052] The connection block 2 is symmetrically fixed with mounting blocks 5, which are used to support the entire drive adjustment control unit 7; the adjustment plate 3 is provided with multiple and evenly distributed on the circumferential surface of the mounting block 5, and the mounting block 5 is provided with a control member 6 for adjusting the distance between the adjustment plate 3 and the surface of the mounting block 5, and the connection block 2 is provided with a drive adjustment control unit 7 for adjusting and locking the position of the adjustment roller 4. The adjustment plate 3 is driven by the control member 6 to drive the multiple adjustment plates 3 to move, thereby changing the diameter of the circle surrounded by the adjustment plates 3 to achieve the adjustment of the cable tension; the adjustment roller 4 is driven to rotate, thereby further adjusting the cable tension and improving the adjustment accuracy, and the position of the adjustment roller 4 can be locked synchronously to improve the overall stability of the device when in use.

[0053] Working principle: When in use, after partially winding the steel cable around the outer surface of the adjustment plate 3, it is passed around the outer surface of any one of the adjustment rollers 4 and the stabilizing rod 401 in turn, so that the steel cable is in an "S" shape, and then the two-way telescopic member 603 is started to extend its output end outward or contract inward, thereby driving the control discs 604 at both ends to move, and the control disc 604 pushes or pulls the control rod 1 601 through the control rod 2 602 to rotate around the connection between the connecting protrusion 6011 and the stabilizing block 8. At this time, the control rod 2 602 drives the adjustment plate 3 to move away from or close to the side of the two-way telescopic member 603, so that the diameter of the circle formed by the multiple adjustment plates 3 increases or decreases, thereby realizing effective adjustment of the steel cable tension according to different scenarios; then the driving member 704 is started to drive the driving block 701 702 and 703, and the adjusting rod 402 is unable to rotate because the adjusting roller 4 is limited by the adjusting block 1 702 and the adjusting block 2 703 at this time. Under the reverse force of the adjusting roller 4, the adjusting block 2 703 is limited, and the locking elastic member 2 708 is compressed, so that the adjusting block 1 702 and the adjusting block 2 703 are gradually misaligned, and the driving member 704 continues to drive. At this time, under the action of the inclined plane, the adjusting roller 4 moves along the inclined planes on the adjusting block 1 702 and the adjusting block 2 703, moves from the adjusting groove 2 706 to the inside of the adjusting groove 1 705, and is located at the bottom of the adjusting block 1 702. While the adjusting roller 4 moves, it drives the adjusting rod 402 to rotate around the axis of the stabilizing rod 401, so that the adjusting roller 4 pushes the steel cable bypassing its surface to the outside, and further fine-tunes the tension of the steel cable to improve the adjustment accuracy.

[0054] The above description is only by way of illustration of certain exemplary embodiments of the present invention. It is undoubted that those skilled in the art can modify the described embodiments in various ways without departing from the spirit and scope of the present invention. Therefore, the above drawings and descriptions are illustrative in nature and should not be construed as limiting the scope of protection of the claims of the present invention.

Claims

1. A steel cable guiding device for a tower crane, comprising a connecting rod (1) connected to the tower crane, wherein two connecting rods (1) are provided, and a connecting block (2) is fixedly provided between opposite sides of the two connecting rods (1), characterized in that: The steel cable guiding device of the tower crane further comprises an adjusting plate (3) and an adjusting roller (4) for adjusting the tension of the steel cable, wherein the adjusting roller (4) is located below the adjusting plate (3); An adjustment hole (201) is formed through the interior of the connection block (2), a stabilizing rod (401) is rotatably disposed inside the adjustment hole (201), an adjustment rod (402) is symmetrically fixedly disposed on the outer surface of the stabilizing rod (401), and the adjustment roller (4) is rotatably disposed between the ends of the two adjustment rods (402); The connecting block (2) is symmetrically fixed with a mounting block (5); the adjusting plate (3) is provided with a plurality of evenly distributed circumferential surfaces of the mounting block (5); the mounting block (5) is provided with a control member (6) for adjusting the distance between the adjusting plate (3) and the surface of the mounting block (5); and the connecting block (2) is provided with a driving adjustment control member (7) for adjusting and locking the position of the adjusting roller (4); The control member (6) comprises a control rod 1 (601) having one end rotatably connected to the adjustment plate (3), a control rod 2 (602) being rotatably arranged at the other end of the control rod 1 (601), and an end of the control rod 2 (602) away from the control rod 1 (601) being rotatably arranged with the mounting block (5); The driving and adjusting control unit (7) comprises a driving block (701) located above the connecting block (2); a first adjusting block (702) and a second adjusting block (703) are slidably arranged on the inner wall of the driving block (701) and are staggered in distribution; a driving member (704) is fixedly arranged inside the connecting block (2); an output end of the driving member (704) passes through the connecting block (2) and is fixedly arranged on the driving block (701); A stabilizing block (8) is fixedly arranged on opposite sides of the two mounting blocks (5), a guide groove (9) is penetrated through the stabilizing block (8), and the second control rod (602) penetrates the guide groove (9) and is arranged in contact with the inner surface thereof; A bidirectional telescopic member (603) is fixedly arranged between opposite sides of the two stabilizing blocks (8), a control disc (604) is fixedly arranged at the output end of each bidirectional telescopic member (603), and an end of the second control rod (602) is rotatably arranged with an outer surface of the control disc (604); One side of the control rod 1 (601) extends outward to form a connecting protrusion (6011), and the connecting protrusion (6011) is rotatably arranged with the outer surface of the stabilizing block (8); The driving block (701) is symmetrically provided with a first regulating groove (705) and a second regulating groove (706); the first regulating block (702) is slidably arranged inside the first regulating groove (705); the second regulating block (703) is slidably arranged inside the second regulating groove (706); and the end of the regulating roller (4) extends into the interior of the second regulating groove (706) and fits with the top of the second regulating block (703); A locking elastic member 1 (707) is fixedly disposed between the regulating block 1 (702) and the inner top wall of the regulating groove 1 (705), and a locking elastic member 2 (708) is fixedly disposed between the regulating block 2 (703) and the inner bottom wall of the regulating groove 2 (706); The upper and lower sides of the opposite sides of the regulating block 1 (702) and the regulating block 2 (703) are both inclined surfaces.

2. A wire rope guiding device for a tower crane according to claim 1, characterized in that: The adjustment plate (3) is designed to be arc-shaped, and its outer surface is provided with a spiral groove for placing and limiting the steel cable.

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