Pre-tightening device and method for clamping piece type wedge-shaped anchorage device of composite material bar

Abstract

The invention provides a pre-tightening device and method for a clamping piece type wedge-shaped anchorage device of a composite material bar, and relates to the field of composite material bar type inhaul cables and prestress. The pre-tightening device comprises a pre-tightening box, and a jack, a pressure sensor, a pushing block, a wedge-shaped clamping piece, an anchor cup, a coordination block and the composite material bar are sequentially arranged in the pre-tightening box; the composite material bar sequentially penetrates through the anchor cup and the coordination block, the wedge-shaped clamping piece is installed at the end, extending out of the anchor cup, of the composite material bar, and the jack applies pre-tightening force to the composite material bar, the anchor cup and the wedge-shaped clamping piece through the pushing block so that the composite material bar, the anchor cup and the wedge-shaped clamping piece can be pre-tightened into a whole. The pressure sensor is used for measuring the applied pre-tightening force. The device is light in size, can be suitable for pre-tightening the wedge-shaped anchorage device in a laboratory, can adapt to inhaul cables with different lengths, and can quickly and accurately apply pre-tightening force to the clamping piece of the wedge-shaped anchorage device.

Description

Technical Field

[0001] The invention relates to the technical field of composite material rod type cables and prestressing technology, in particular to a pre-tightening device and method for a clip-type wedge-shaped anchor of a composite material rod. Background Art

[0002] A wedge anchor is a mechanical anchor that anchors composite rods by combining a wedge-shaped clip with the tapered anchor cup. It is primarily used in prestressed engineering projects such as bridges and large-span structures. Before the wedge anchor is operational, a pre-tightening force must be applied to the wedge clip to prevent the composite rod from slipping. In the laboratory, the cable length may far exceed the limits of traditional equipment, making it impossible to pre-tighten the wedge anchor. However, the pre-tightening devices used in actual projects are large and bulky, making them unsuitable for pre-tightening wedge anchors in the laboratory. This makes it impossible to quickly and accurately pre-tighten the clips of the wedge anchor in the laboratory. Summary of the Invention

[0003] In order to solve the technical problems existing in the prior art, the present invention provides a pre-tightening device and method for a clip-type wedge-shaped anchor for composite material rods. The technical solution is as follows:

[0004] A pre-tightening device for a clip-type wedge-shaped anchor of a composite material rod comprises a pre-tightening box, in which a jack, a pressure sensor, a push block, a wedge-shaped clip, an anchor cup, a coordination block and a composite material rod are sequentially arranged, the composite material rod passes through the anchor cup and the coordination block in sequence and the wedge-shaped clip is installed at the end of the composite material rod extending out of the anchor cup, the jack applies a pre-tightening force to the composite material rod, the anchor cup and the wedge-shaped clip through the push block so that the composite material rod, the anchor cup and the wedge-shaped clip are pre-tightened into a whole, and the pressure sensor is used to measure the applied pre-tightening force.

[0005] Optionally, the pre-tensioning box is a five-sided box-shaped structure, and a placement slot and a through slot are provided on the pre-tensioning box, the through slot is connected to the placement slot, and the through slot and the placement slot are connected to the outside world; a non-through hole is provided on the surface where the placement slot is connected to the through slot, the through slot passes through the non-through hole, and the non-through hole connects the placement slot with the through slot, and the diameter of the non-through hole is greater than the width of the through slot; short beams are provided at both ends of the pre-tensioning box.

[0006] Optionally, the coordination block is a columnar structure, and the coordination block supports vertical disassembly along the axis to obtain two identical semi-cylindrical structures. A first through hole is opened at one end of the coordination block, and a second through hole is opened at the other end of the coordination block. The first through hole is connected to the second through hole, and the axis of the first through hole and the axis of the second through hole coincide with the axis of the coordination block. The diameter of the first through hole is greater than the diameter of the second through hole; the outer diameter of the coordination block is equal to the inner diameter of the non-through hole, the height of the coordination block is greater than the depth of the non-through hole, and the coordination block supports insertion into the non-through hole.

[0007] Optionally, the anchor cup is a columnar structure with a wedge-shaped through hole in the center, the outer diameter of the anchor cup is adapted to the diameter of the first through hole, one end of the anchor cup is supported and inserted into the first through hole, and the other end of the composite material rod passes through the second through hole and extends from the through groove to the outside of the preload box.

[0008] Optionally, the end of the wedge-shaped clip abuts against the pushing block, and the pushing block includes a disc, a pushing column is set at the center of one end of the disc, and the pushing column abuts against the wedge-shaped clip, and the other end of the disc abuts against the pushing head of the jack through the pressure sensor, and the jack is limited at one end in the placement groove by the jack limiter.

[0009] Optionally, the jack limiter is installed at one end of the placement groove, and the jack limiter is a rectangular block with a semicircular through groove on the top, and the bottom surface of the jack limiter is installed on the bottom surface of the placement groove, the inner diameter of the semicircular through groove is adapted to the outer diameter of the jack, and the jack is fixedly clamped in the semicircular through groove.

[0010] Optionally, the diameter of the second through hole of the coordination block is smaller than the diameter of the anchor cup, the aperture of the first end of the wedge-shaped through hole is smaller than the aperture of the second end of the wedge-shaped through hole, the diameter of the second through hole of the coordination block is larger than the aperture of the first end of the wedge-shaped through hole; the diameter of the push column is smaller than the aperture of the second end of the wedge-shaped through hole.

[0011] Optionally, the center of the semicircular through groove, the axis of the jack, the axis of the pressure sensor, the axis of the placement groove, the axis of the push block, the axis of the wedge-shaped clip, the axis of the anchor cup, the axis of the coordination block and the axis of the through groove are located on the same straight line.

[0012] A method for pre-tightening a clip-on wedge-shaped anchor for a composite material rod, comprising the pre-tightening device for the clip-on wedge-shaped anchor for the composite material rod, the method comprising:

[0013] S1. Install the composite rod, coordination block, anchor cup and wedge clip together;

[0014] S2, installing the jack, the pressure sensor, the push block, the wedge-shaped clip, the anchor cup, the coordination block and the composite material rod into the placement groove;

[0015] S3, starting the jack, which applies a pre-tightening force to the wedge-shaped clip in stages through the push block until the pressure value sensed by the pressure sensor reaches a preset pressure value, and then closing the jack;

[0016] S4. Take out the wedge-shaped clip, anchor cup, coordination block and composite material rod from the pre-tightening box, vertically disassemble the coordination block along the axis of the coordination block, so that the composite material rod is separated from the coordination block. At this time, the anchor cup, wedge-shaped clip and composite material rod are pre-tightened as a whole, and pre-tightening is completed.

[0017] Optionally, the step of assembling the composite material rod, the coordination block, the anchor cup and the wedge-shaped clip together in S1 includes:

[0018] Pass the composite material rod through the anchor cup and the coordination block in sequence, so that one end of the composite material rod extends out of the second through hole of the coordination block, install a wedge-shaped clip on the other end of the composite material rod, and insert the anchor cup into the first through hole;

[0019] The step of installing the jack, the pressure sensor, the push block, the wedge-shaped clip, the anchor cup, the coordination block, and the composite material rod into the placement groove in S2 includes:

[0020] The jack is clamped in the semicircular through groove of the jack limiter, and a pressure sensor is installed on the pushing head of the jack so that the pressure sensor abuts against the disc of the pushing block. The coordination block is inserted into the non-through hole of the placement groove, and one end of the composite material rod extending from the second through hole of the coordination block extends through the through groove to the outside of the preload box, and the pushing column of the pushing block abuts against the wedge-shaped clip.

[0021] The beneficial effects brought about by the technical solution provided by the embodiment of the present invention include at least:

[0022] The device in the solution of the present invention is lightweight and can be used for pre-tightening of laboratory wedge anchors. The pre-tightening box of the device is provided with a through groove that can accommodate the passage of cables of different lengths. The pre-tightening force can be quickly and accurately applied to the clip of the wedge anchor through the jack. At the same time, the applied pre-tightening force can be accurately controlled by using a pressure sensor to meet the experimental requirements. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0024] Figure 1 A schematic structural diagram of a pre-tightening device for a clip-type wedge-shaped anchor for a composite material rod provided by the present invention;

[0025] Figure 2 An exploded view of a pre-tightening device of a clip-type wedge-shaped anchor for a composite material rod provided by the present invention;

[0026] Figure 3 A schematic structural diagram of a pre-tightening box of a pre-tightening device of a clip-type wedge-shaped anchor for a composite material rod provided by the present invention;

[0027] Figure 4 A schematic structural diagram of a coordination block of a pre-tightening device of a clip-type wedge-shaped anchor for a composite material rod provided by the present invention;

[0028] Figure 5 A schematic structural diagram of a jack stopper of a pre-tightening device of a clip-type wedge-shaped anchor for a composite material rod provided by the present invention;

[0029] Figure 6 This is a structural schematic diagram of a push block of a pre-tightening device of a clip-type wedge-shaped anchor for composite material rods provided by the present invention.

[0030] Reference numerals:

[0031] 1. Preload box; 2. Coordinating block; 3. Jack limiter; 4. Push block; 5. Pressure sensor; 6. Jack; 7. Composite material rod; 8. Anchor cup; 9. Wedge clip; 11. Through slot; 12. Non-through hole; 13. First short beam; 14. Second short beam; 15. Placement slot; 21. Second through hole; 22. First through hole; 31. Semicircular through slot; 41. Push column; 42. Disc. DETAILED DESCRIPTION

[0032] To make the purpose, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the described embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0033] Unless otherwise defined, the technical or scientific terms used in the present invention shall have the usual meaning understood by persons of ordinary skill in the field to which the present invention belongs. The words "first", "second" and similar terms used in the present invention do not indicate any order, quantity or importance, but are only used to distinguish different components. Similarly, words such as "one", "an" or "the" do not indicate a quantity limitation, but rather indicate the presence of at least one. Words such as "include" or "comprise" mean that the elements or objects preceding the word include the elements or objects listed after the word and their equivalents, without excluding other elements or objects. Words such as "connect" or "connected" are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect.

[0034] It should be noted that the terms "up", "down", "left", "right", "front" and "back" used in the present invention are only used to indicate relative position relationships. When the absolute position of the object being described changes, the relative position relationship may also change accordingly.

[0035] like Figures 1-6 As shown, this embodiment provides a pre-tightening device for a clip-type wedge-shaped anchor of a composite material rod, including a pre-tightening box 1. The pre-tightening box 1 is a five-sided box structure, that is, the top surface of the pre-tightening box 1 is open and connected to the outside world, and a placement groove 15 and a through groove 11 are provided on the pre-tightening box 1. Since the top surface of the pre-tightening box 1 is open, the placement groove 15 and the top surface of the through groove 11 are connected to the outside world, the through groove 11 is connected to the placement groove 15 and the axes of the two coincide, the width of the placement groove 15 is greater than the width of the through groove 11, and a non-through hole 12 is provided on the surface where the placement groove 15 and the through groove 11 are connected, the center of the non-through hole 12 is located on the axis of the through groove 11 and the placement groove 15, and the diameter of the non-through hole 12 is greater than the width of the through groove 11, the bottom surface of the placement groove 15 is connected to the bottom surface of the through groove 11, the through groove 11 passes through the non-through hole 12, and the non-through hole 12 connects the placement groove 15 with the through groove 11. A first short beam 13 is provided at one end of the pre-tension box 1 , a second short beam 14 is provided at the other end of the pre-tension box, and one end of the through slot 11 passes through the first short beam 13 and communicates with the outside.

[0036] The preload box 1 is provided with a jack 6, a pressure sensor 5, a push block 4, a wedge-shaped clip 9, an anchor cup 8, a coordination block 2, and a composite material rod 7, arranged in order from the direction near the second short beam 14. The composite material rod 7 sequentially passes through the anchor cup 8 and the coordination block 2, and the wedge-shaped clip 9 is attached to the end of the composite material rod 7 extending beyond the anchor cup 8. The coordination block 2 is a columnar structure that can be vertically disassembled along its axis to form two identical semi-cylindrical structures. A first through hole 22 is defined at one end of the coordination block 2, and a second through hole 21 is defined at the other end. The first through hole 22 communicates with the second through hole 21, and the axes of the first through hole 22 and the second through hole 21 coincide with the axis of the coordination block 2. The diameter of the first through hole 22 is greater than the diameter of the second through hole 21. The outer diameter of the coordination block 2 is equal to and matches the inner diameter of the non-through hole 12. The height of the coordination block 2 is greater than the depth of the non-through hole 12, and the coordination block 2 is inserted into the non-through hole 12.

[0037] The anchor cup 8 is a columnar structure with a wedge-shaped through hole in the center. The outer diameter of the anchor cup 8 is equal to and fits with the diameter of the first through hole 22. One end of the anchor cup 8 is inserted into the first through hole 22, and the composite material rod 7 passes through the wedge-shaped through hole and penetrates the anchor cup 8. Since the anchor cup 8 is inserted into the first through hole 22 of the coordination block 2, the composite material rod 7 passes through the wedge-shaped through hole and extends into the coordination block. One end of the composite material rod 7 passes through the second through hole 21 of the coordination block 2 and passes through the through groove 11, and extends from the through groove 11 to the outside of the preload box 1. The other end of the composite material rod 7 extends to the outside of the anchor cup 8 and is clamped by the wedge-shaped clip 9. The diameter of the second through hole 21 of the coordination block 2 is smaller than the diameter of the anchor cup 8, the aperture of the first end of the wedge-shaped through hole is smaller than the aperture of the second end of the wedge-shaped through hole, and the diameter of the second through hole 21 of the coordination block 2 is larger than the aperture of the first end of the wedge-shaped through hole; the second end of the wedge-shaped through hole is close to the wedge-shaped clip 9, and the end of the wedge-shaped clip 9 abuts the pushing block 4, and the pushing block 4 includes a disc 42, and a pushing column 41 is set at the center of one end of the disc 42, and the pushing column 41 abuts the wedge clip 9. The other end of the disc 42 abuts with the pushing head of the jack 6 through the pressure sensor 5. The jack 6 is limited in the placement groove 15 near one end of the second short beam 14 by the jack limiter 3, and the diameter of the pushing column 41 is smaller than the aperture of the second end of the wedge-shaped through hole.

[0038] The jack stopper 3 is mounted within the placement slot 15, near one end of the second short beam 14. The jack stopper 3 is a rectangular block with a semicircular through-slot 31 at its top. The bottom surface of the jack stopper 3 is mounted on the bottom surface of the placement slot 15. The inner diameter of the semicircular through-slot 31 matches the outer diameter of the jack 6, and the jack 6 is fixedly engaged within the semicircular through-slot 31. The center of the semicircular through-slot 31, the axis of the jack 6, the axis of the pressure sensor 5, the axis of the placement slot 15, the axis of the push block 4, the axis of the wedge-shaped clip 9, the axis of the anchor cup 8, the axis of the coordination block 2, and the axis of the through-slot 11 are all aligned. The jack 6 applies a preload force to the composite rod 7, the anchor cup 8, and the wedge-shaped clip 9 through the push block 4, thereby preloading the composite rod 7, the anchor cup 8, and the wedge-shaped clip 9 into a single unit. The pressure sensor 5 is used to measure the preload force applied by the jack 6.

[0039] A method for pre-tightening a clip-type wedge-shaped anchor for a composite material rod, the method comprising:

[0040] S1, assembling the composite rod 7, the coordination block 2, the anchor cup 8 and the wedge-shaped clip 9 together;

[0041] Pass the composite rod 7 through the anchor cup 8 and the coordination block 2 in sequence, insert the anchor cup 8 into the first through hole 22, and pass the composite rod 7 from the second end of the wedge-shaped through hole and out from the second through hole 21 of the coordination block 2. Install the wedge-shaped clip 9 on the end of the composite rod 7 that extends out of the anchor cup 8;

[0042] S2, installing the jack 6, the pressure sensor 5, the push block 4, the wedge-shaped clip 9, the anchor cup 8, the coordination block 2 and the composite material rod 7 into the placement groove 15;

[0043] The jack 6 is clamped into the semicircular through-slot 31 of the jack limiter 3, and the pressure sensor 5 is installed on the pushing head of the jack 6 so that the pressure sensor 5 abuts against the disc 42 of the pushing block 4. The coordination block 2 is inserted into the non-through hole 12 of the placement groove 15. One end of the composite material rod 7 extending from the second through-hole 21 of the coordination block 2 extends through the through-slot 11 to the outside of the preload box 1, and the pushing column 41 of the pushing block 4 abuts against the wedge-shaped clip 9.

[0044] S3, start the jack 6, which applies a pre-tightening force to the wedge-shaped clamp 9 and the composite material rod 7 in stages through the push block 4 until the pressure value sensed by the pressure sensor 5 reaches a preset pressure value, and then close the jack 6;

[0045] S4. Take out the wedge-shaped clip 9, anchor cup 8, coordination block 2 and composite material rod 7 from the preload box 1, disassemble the coordination block 2 vertically along the axis of the coordination block 2, so that the composite material rod 7 is separated from the coordination block 2, and preload the anchor cup 8, wedge-shaped clip 9 and composite material rod 7 as a whole to complete the preload.

[0046] The device in this scheme is lightweight and can be used for pre-tightening of laboratory wedge anchors. The pre-tightening box of the device is provided with a through slot that can accommodate the passage of cables of different lengths. The pre-tightening force can be quickly and accurately applied to the clip of the wedge anchor through the jack. At the same time, the applied pre-tightening force can be accurately controlled by the pressure sensor to meet the experimental requirements.

[0047] The following points need to be explained:

[0048] (1) The drawings of the embodiments of the present invention only relate to the structures related to the embodiments of the present invention. Other structures may refer to conventional designs.

[0049] (2) For the sake of clarity, the thickness of layers or regions in the drawings used to describe the embodiments of the present invention are exaggerated or reduced, that is, these drawings are not drawn to scale. It is understood that when an element such as a layer, film, region, or substrate is referred to as being "on" or "under" another element, the element may be "directly on" or "under" the other element or intervening elements may be present.

[0050] (3) In the absence of conflict, the embodiments of the present invention and the features therein may be combined with each other to form new embodiments.

[0051] The above are only specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. The protection scope of the present invention shall be based on the protection scope of the claims.

Claims

1. A pre-tightening device for a clip-type wedge-shaped anchor of a composite material rod, characterized in that: It includes a pre-tightening box, in which a jack, a pressure sensor, a push block, a wedge-shaped clip, an anchor cup, a coordination block and a composite material rod are arranged in sequence. The composite material rod passes through the anchor cup and the coordination block in sequence, and the wedge-shaped clip is installed at the end of the composite material rod extending out of the anchor cup. The jack applies a pre-tightening force to the composite material rod, the anchor cup and the wedge-shaped clip through the push block so that the composite material rod, the anchor cup and the wedge-shaped clip are pre-tightened into a whole. The pressure sensor is used to measure the applied pre-tightening force.

2. The pre-tightening device of the clip-type wedge anchor for composite material rods according to claim 1, characterized in that: The pre-tensioning box is a five-sided box-shaped structure, with a placement slot and a through slot provided on the pre-tensioning box. The through slot is connected to the placement slot, and the through slot and the placement slot are connected to the outside world. A non-through hole is provided on the surface where the placement slot is connected to the through slot, and the through slot passes through the non-through hole. The non-through hole connects the placement slot with the through slot, and the diameter of the non-through hole is greater than the width of the through slot. Short beams are provided at both ends of the pre-tensioning box.

3. The pre-tightening device of the clip-type wedge-shaped anchor for composite material rods according to claim 2, characterized in that: The coordination block is a columnar structure, and the coordination block supports vertical disassembly along the axis to obtain two identical semi-cylindrical structures. A first through hole is opened at one end of the coordination block, and a second through hole is opened at the other end of the coordination block. The first through hole is connected to the second through hole, and the axis of the first through hole and the axis of the second through hole coincide with the axis of the coordination block. The diameter of the first through hole is greater than the diameter of the second through hole; the outer diameter of the coordination block is equal to the inner diameter of the non-through hole, the height of the coordination block is greater than the depth of the non-through hole, and the coordination block supports insertion into the non-through hole.

4. The pre-tightening device of the clip-type wedge-shaped anchor for composite material rods according to claim 3, characterized in that: The anchor cup is a columnar structure with a wedge-shaped through hole in the center. The outer diameter of the anchor cup is adapted to the diameter of the first through hole. One end of the anchor cup is supported and inserted into the first through hole, and the other end of the composite material rod passes through the second through hole and extends from the through groove to the outside of the preload box.

5. The pre-tightening device of the clip-type wedge-shaped anchor for composite material rods according to claim 4, characterized in that: The end of the wedge-shaped clip abuts against the pushing block, and the pushing block includes a disc. A pushing column is provided at the center of one end of the disc. The pushing column abuts against the wedge-shaped clip. The other end of the disc abuts against the pushing head of the jack through the pressure sensor. The jack is limited at one end in the placement groove by the jack limiter.

6. The pre-tightening device of the clip-type wedge-shaped anchor for composite material rods according to claim 5, characterized in that: The jack limiter is installed at one end of the placement groove. The jack limiter is a rectangular block with a semicircular through groove on the top. The bottom surface of the jack limiter is installed on the bottom surface of the placement groove. The inner diameter of the semicircular through groove is adapted to the outer diameter of the jack, and the jack is fixedly clamped in the semicircular through groove.

7. The pre-tightening device of the clip-type wedge-shaped anchor for composite material rods according to claim 5, characterized in that: The diameter of the second through hole of the coordination block is smaller than the diameter of the anchor cup, the aperture of the first end of the wedge-shaped through hole is smaller than the aperture of the second end of the wedge-shaped through hole, the diameter of the second through hole of the coordination block is larger than the aperture of the first end of the wedge-shaped through hole; the diameter of the push column is smaller than the aperture of the second end of the wedge-shaped through hole.

8. The pre-tightening device of the clip-type wedge-shaped anchor for composite material rods according to claim 6, characterized in that: The center of the semicircular through groove, the axis of the jack, the axis of the pressure sensor, the axis of the placement groove, the axis of the push block, the axis of the wedge-shaped clip, the axis of the anchor cup, the axis of the coordination block and the axis of the through groove are located on the same straight line.

9. A method for pre-tightening a clip-type wedge anchor for a composite material rod, characterized in that: A pre-tightening device comprising a clip-type wedge-shaped anchor for a composite material rod according to any one of claims 1 to 8, wherein the method comprises: S1. Install the composite rod, coordination block, anchor cup and wedge clip together; S2, installing the jack, the pressure sensor, the push block, the wedge-shaped clip, the anchor cup, the coordination block and the composite material rod into the placement groove; S3, starting the jack, which applies a pre-tightening force to the wedge-shaped clip in stages through the push block until the pressure value sensed by the pressure sensor reaches a preset pressure value, and then closing the jack; S4. Take out the wedge-shaped clip, anchor cup, coordination block and composite material rod from the pre-tightening box, vertically disassemble the coordination block along the axis of the coordination block, so that the composite material rod is separated from the coordination block. At this time, the anchor cup, wedge-shaped clip and composite material rod are pre-tightened as a whole, and pre-tightening is completed.

10. The method for pre-tightening a clip-type wedge-shaped anchor for a composite material rod according to claim 9, characterized in that: The step of assembling the composite rod, the coordination block, the anchor cup and the wedge-shaped clip together as described in S1 includes: Pass the composite material rod through the anchor cup and the coordination block in sequence, so that one end of the composite material rod extends out of the second through hole of the coordination block, install a wedge-shaped clip on the other end of the composite material rod, and insert the anchor cup into the first through hole; The step of installing the jack, the pressure sensor, the push block, the wedge-shaped clip, the anchor cup, the coordination block, and the composite material rod into the placement groove in S2 includes: The jack is clamped in the semicircular through groove of the jack limiter, and a pressure sensor is installed on the pushing head of the jack so that the pressure sensor abuts against the disc of the pushing block. The coordination block is inserted into the non-through hole of the placement groove, and one end of the composite material rod extending from the second through hole of the coordination block extends through the through groove to the outside of the preload box, and the pushing column of the pushing block abuts against the wedge-shaped clip.

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