A casing and anticorrosive tubing drift machine

Abstract

This utility model discloses a gauging machine for oil casing and anti-corrosion tubing, belonging to the field of pipe gauging technology. This gauging machine for oil casing and anti-corrosion tubing includes a placement component, a gauging component, and a resetting component. The placement component is used to place two tubings to be gauged. The gauging component is used to gaug the internal diameter of the tubing. The resetting component is used to reset the gauging head. The gauging component includes a pair of sealing plates, each with a gauging head on one side. The outer wall of the gauging head has several moving grooves, and each moving groove has a sliding block inside. The gauging head has a cavity inside, and an electric telescopic rod is installed on one side of the inner wall of the cavity. A circular plate is installed at the movable end of the electric telescopic rod. Several first movable seats are installed on the outer wall of the circular plate. Connecting rods are rotatably connected to both sides of the first movable seats. A pair of connecting rods are rotatably connected to a second movable seat at the end furthest from the first movable seats. One side of the outer wall of the second movable seat is fixedly connected to one side of the moving block.

Description

Technical Field

[0001] This utility model relates to the field of pipe diameter measurement technology, specifically a diameter measuring machine for oil casing and anti-corrosion oil pipe. Background Technology

[0002] A caliper is a testing device used in the production of simple pipes to check whether the pipe is bent and whether the inner diameter of the pipe allows the caliper bar to pass freely. Most methods employ either mechanical or pneumatic manual caliping. The pneumatic manual caliping method involves manually picking up the caliper bar returned by a belt conveyor, aligning it with one end of the simple pipe to be caliped, and then manually blowing the caliper bar out using an air gun. At the other end, a caliper stop is installed to block the caliper bar from exiting the pipe. The caliper bar falls back into the belt conveyor and is returned to the blowing end of the pipe. This cycle is repeated to complete the pipe caliper test.

[0003] For example, Chinese patent CN220479468U discloses a simple automatic pipe caliper, including a base plate. A support frame is movably mounted on one side of the top of the base plate. An air gun is fixedly mounted on the top inner side of the support frame. A multi-stage electric telescopic rod is fixedly mounted on the bottom inner side of the support frame. A support plate is fixedly mounted on the top of the multi-stage electric telescopic rod. A caliper rod abuts against a groove in the top of the support plate. Multiple pipes are evenly distributed on the top of the base plate. One end of the caliper rod abuts against the output end of the air gun. By extending and retracting the multi-stage electric push rod, the caliper rod transported back by the belt conveyor can be automatically lifted. The lifted caliper rod can return to the air blowing end of the air gun, eliminating the need for manual picking up of the caliper rod by the worker, saving effort. Furthermore, the worker can stay away from the caliper machine when the caliper rod is lifted, so that if the air gun is accidentally activated and the caliper rod flies out, it is unlikely to injure the worker, making it safe and convenient.

[0004] The technical solution described in this paper has the drawback that the size of the gauging bar is not easy to adjust according to the inner diameter of the oil pipe during actual use. The gauging bar has a fixed size and shape, which makes it less adaptable to different specifications of oil casing and anti-corrosion oil pipes. It is not easy to adapt to various specifications of oil pipes, which leads to the need to replace different models of gauging machines, thereby reducing work efficiency. Utility Model Content

[0005] The purpose of this utility model is to provide a bore gauge for oil casing and anti-corrosion oil pipes to solve the problems mentioned in the background art.

[0006] In view of the above problems, the technical solution proposed by this utility model is as follows:

[0007] A gauging machine for oil casing and corrosion-resistant tubing includes a placement component, a gauging component, and a resetting component. The gauging component is positioned above the placement component, and the resetting component is positioned outside the gauging component. The placement component is used to place two tubings to be gauged. The gauging component is used to gaug the internal diameter of the tubings. The resetting component is used to reset the gauging head. The gauging component includes a pair of sealing plates, each of which has a gauging head on one side. The outer wall of the gauging head has several moving grooves, and each of the moving grooves has a sliding block. The gauging head has a cavity inside, and an electric telescopic rod is installed on one side of the inner wall of the cavity. A circular plate is installed at the movable end of the electric telescopic rod. Several first movable seats are installed on the outer wall of the circular plate. Connecting rods are rotatably connected to both sides of the outer side of each first movable seat. A pair of connecting rods are rotatably connected to a second movable seat at the end away from the first movable seat. One side of the outer wall of the second movable seat is fixedly connected to one side of the moving block.

[0008] Furthermore, each of the pair of sealing plates has a through hole at its center, and the pair of sealing plates is connected to an air outlet pipe on the side opposite to the through head. The pair of air outlet pipes are connected to a duct at the ends away from the sealing plates, and the duct is provided with an air inlet.

[0009] The beneficial effect of adopting the above-mentioned further solution is that a gas delivery channel is formed by setting up an air inlet, air duct and air outlet; the setting of the air inlet facilitates compressed air to enter the interior of the air duct through the air inlet; when the oil pipe to be caliped is placed on the placement seat and one end of it abuts against the sealing plate, the caliper head is located inside one end of the oil pipe, i.e., the starting position. Since the air duct is connected to the two air outlets, the compressed air is discharged through the air outlet and blown through the through hole to move the caliper head inside one end of the oil pipe to achieve the caliping operation, thereby realizing the pneumatic caliping operation.

[0010] Furthermore, a column is installed at the bottom of the air duct, and a booster pump is installed on one side of the outer wall of the column. The air outlet of the booster pump is connected to the air inlet through a pipe, and the air inlet of the booster pump can be connected to an external air gun.

[0011] The beneficial effects of adopting the above-mentioned further solution are that the placement component and the through-hole component are integrated by setting the column; by setting the booster pump, and the air outlet of the booster pump is connected to the air inlet of the air duct through the pipe, the pressure of the gas entering the air duct is increased, and the gas blown out by the air gun becomes high-pressure gas after passing through the booster pump and enters the air duct through the pipe and the air inlet.

[0012] Furthermore, the ferrule head is frustoconical at the end furthest from the sealing plate.

[0013] The beneficial effect of adopting the above-mentioned further solution is that, since the end of the sizing head is frustoconical in shape away from the sealing plate, the sizing head has a guiding effect when entering the oil pipe, reducing the difficulty and resistance of the sizing head entering the oil pipe, and improving the smoothness and success rate of the sizing operation.

[0014] Furthermore, the placement assembly includes a base plate, the upper end of which is fixedly connected to the bottom end of the column. A pair of placement seats are installed on the base plate, and each pair of placement seats is provided with an oil pipe. One end of each of the two oil pipes is tightly fitted to the side of the sealing plate away from the air duct. Two through heads are respectively disposed inside the two oil pipes near the sealing plate.

[0015] The beneficial effect of adopting the above-mentioned further solution is that by setting up a pair of placement seats, it is convenient to use hoisting equipment to place the two oil pipes to be caliped on the pair of placement seats respectively, so that the caliping operation of the two oil pipes can be carried out simultaneously. After placement, the oil pipe is pushed towards one end of the sealing plate so that one end of the oil pipe is tightly fitted with the side of the sealing plate away from the air pipe. Then, a sealing sleeve is put on the outside of the end of the oil pipe away from the sealing plate. The tight fit between the oil pipe and the sealing plate can ensure that when the high-pressure gas is blown into the oil pipe through the through hole for caliping operation, it will not leak from the connection between the oil pipe and the sealing plate.

[0016] Furthermore, the reset assembly includes a pair of brackets, which are respectively installed on the outer walls of the air duct near both ends. Each bracket has an installation cylinder installed at the end away from the air duct. A take-up roller is rotatably connected inside the installation cylinder. A twisted rope is wound around the outside of the take-up roller. One end of the twisted rope passes through the installation cylinder, the air duct, and the through hole and is fixedly connected to the end of the through head near the sealing plate.

[0017] The beneficial effects of adopting the above-mentioned further solution are that, by setting up the bracket, which is used to install and fix the mounting cylinder, the reset component and the gauging component are connected, enabling the reset component to stably perform the gauging head reset operation; the setting of the take-up roller and the winch forms the gauging head reset mechanism. After the gauging operation is completed, by rotating the take-up roller, the take-up roller winds up the winch, and the winch pulls the gauging head, causing it to smoothly retract from inside the oil pipe to the initial position and abut against the sealing plate, realizing the automatic reset of the gauging head, reducing manual operation, improving work efficiency, and ensuring the accuracy of the gauging head reset position each time.

[0018] Furthermore, one end of the take-up roller passes through the mounting cylinder and is connected to a turntable. One side of the turntable is rotatably connected to one side of the outer wall of the mounting cylinder. A first screw hole is provided on the turntable, and a second screw hole is provided on the mounting cylinder near the first screw hole. A bolt is threaded between the first screw hole and the second screw hole, and an internal hexagonal groove is provided inside one end of the bolt.

[0019] The beneficial effects of adopting the above-mentioned further solution are as follows: The turntable facilitates the operator's rotation of the take-up roller. Manually rotating the turntable drives the take-up roller to rotate, thereby enabling the winding and unwinding of the cable and controlling the gauging head's gauging or resetting. Through the cooperation of the first screw hole, the second screw hole, and the bolt, when the gauging head needs to be gauged, the bolt is loosened and removed. At this time, the take-up roller can rotate freely, allowing the gauging head to perform the gauging work under the action of high-pressure gas. Simultaneously, under the action of the cable, the take-up roller is in an unwinding state. When the gauging operation is completed and the gauging head needs to be reset, the bolt is loosened and removed. The user manually rotates the turntable to rotate the take-up roller to wind the cable. At this time, the first screw hole is aligned with the second screw hole again, and the bolt is reinstalled, preventing the take-up roller from rotating on its own under the influence of external factors and ensuring the stability of the gauging head's position after resetting. The internal hexagonal groove facilitates the use of tools such as an internal hexagonal wrench to tighten or loosen the bolts, improving the convenience and efficiency of operation.

[0020] Compared with the prior art, the beneficial effects of this utility model are as follows: This oil casing and anti-corrosion oil pipe caliper, by setting up a placement component, can simultaneously place two oil pipes to be caliped, improving caliping efficiency. When the inner diameter of the oil pipe is larger than the size of the caliper head, the electric telescopic rod is used. When the electric telescopic rod is activated, its movable end retracts, driving the circular plate to move. The circular plate causes the connecting rod to rotate and move through the first movable seat. The rotation and movement of the connecting rod are then transmitted to the moving block through the second movable seat, causing the moving block to slide in the moving groove, thereby changing the outer diameter of the caliper head to adapt to different oil pipe inner diameters and complete the caliping operation. The sealing plate fits and seals the oil pipe end. In conjunction with the air outlet pipe, air pipe, and booster pump, the air inlet of the booster pump can be connected to the external equipment air gun. The gas blown out by the air gun passes through the booster pump to form high-pressure gas and enters the air pipe through the pipe and air inlet. It blows the caliper head through the through hole to move inside the oil pipe, thereby realizing the caliping operation. Attached Figure Description

[0021] Figure 1 A three-dimensional structural schematic diagram of a bore gauge for oil casing and corrosion-resistant oil pipe provided by this utility model;

[0022] Figure 2 A three-dimensional structural schematic diagram of the placement assembly of a bore gauge for oil casing and anti-corrosion oil pipe provided by this utility model;

[0023] Figure 3 An exploded three-dimensional structural diagram of the gauging assembly of a gauging machine for oil casing and anti-corrosion oil pipe provided by this utility model;

[0024] Figure 4 A top cross-sectional view of the resetting assembly of a gauging machine for oil casing and anti-corrosion oil pipe provided by this utility model;

[0025] Figure 5An exploded three-dimensional structural diagram of the gauging head of a gauging machine for oil casing and anti-corrosion oil pipe provided by this utility model.

[0026] In the diagram: 1. Placement component; 11. Base plate; 12. Placement seat; 2. Through-hole assembly; 21. Column; 22. Air duct; 23. Sealing plate; 24. Through hole; 25. Through-hole head; 26. Moving groove; 27. Moving block; 28. Electric telescopic rod; 29. ​​Circular plate; 210. First movable seat; 211. Connecting rod; 212. Second movable seat; 213. Booster pump; 3. Reset assembly; 31. Bracket; 32. Mounting cylinder; 33. Take-up roller; 34. Winding cable; 35. Turntable; 36. Bolt. Detailed Implementation

[0027] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0028] Please see Figures 1-5This utility model provides a technical solution: a caliper for oil casing and anti-corrosion tubing, including a placement component 1, a caliper 2, and a reset component 3. The caliper 2 is positioned above the placement component 1, and the reset component 3 is positioned outside the caliper 2. The placement component 1 is used to place two tubings to be caliped, the caliper 2 is used to caliper the inside of the tubing, and the reset component 3 is used to reset the caliper head 25. The caliper 2 includes a pair of sealing plates 23, each with a caliper head 25 on one side. The outer wall of the caliper head 25 has several moving grooves 26, and each moving groove 26 has a sliding moving block 27 inside. The caliper head 25 has a cavity inside, and an electric telescopic rod 28 is installed on one side of the inner wall of the cavity. A circular plate 29 is installed on the movable end of the electric telescopic rod 28, and several first movable seats 210 are installed on the outer wall of the circular plate 29. Both sides of the movable seat 210 are rotatably connected to connecting rods 211. A pair of connecting rods 211 are rotatably connected to a second movable seat 212 at the end away from the first movable seat 210. One side of the outer wall of the second movable seat 212 is fixedly connected to one side of the moving block 27. By setting the placement component 1, two oil pipes to be caliped can be placed at the same time, improving the caliping efficiency. When the inner diameter of the oil pipe is larger than the size of the caliper head 25, the electric telescopic rod 28 is used. When the electric telescopic rod 28 is activated, its movable end retracts, driving the circular plate 29 to move. The circular plate 29 causes the connecting rods 211 to rotate and move through the first movable seat 210. The rotation and movement of the connecting rods 211 are then transmitted to the moving block 27 through the second movable seat 212, causing the moving block 27 to slide in the moving groove 26, thereby realizing the change of the outer diameter of the caliper head 25 and adapting to different inner diameters of oil pipes to complete the caliping operation.

[0029] Please see Figures 1-5This utility model provides a technical solution: A through hole 24 is provided at the center of each of a pair of sealing plates 23, and an air outlet pipe is connected to the side of the pair of sealing plates 23 opposite to the through head 25. A duct 22 is connected between the ends of the pair of air outlet pipes away from the sealing plates 23. An air inlet is provided on the duct 22. A column 21 is installed at the bottom end of the duct 22. A booster pump 213 is installed on one side of the outer wall of the column 21. The air outlet of the booster pump 213 is connected to the air inlet via a pipe, and the air inlet of the booster pump 213 can be connected to an external air gun. The through head 25 is frustoconical at the end away from the sealing plates 23. The placement assembly 1 includes a base plate 11, the upper end of which is fixedly connected to the bottom end of the column 21. A pair of placement seats 12 are installed on the base plate 11, and each of the placement seats 12 is provided with an oil pipe. One end of each oil pipe is tightly fitted to the side of the sealing plate 23 away from the duct 22. The two through heads 25 are respectively located on two... When the oil pipe to be caliped is placed on the placement seat 12 and its end abuts against the sealing plate 23, the caliper head 25 is located inside the oil pipe at one end, i.e., the starting position. The air inlet of the booster pump 213 can be connected to the external air gun. The air outlet of the booster pump 213 is connected to the air inlet of the air pipe 22 through a pipe. The gas blown out by the air gun is formed into high pressure gas after passing through the booster pump 213 and enters the air pipe 22 through the pipe and the air inlet. Compressed air enters the air pipe 22 through the air inlet, is discharged through the air outlet pipe, and blows the caliper head 25 inside the oil pipe through the through hole 24 to move inside the oil pipe to achieve caliper operation, thereby realizing pneumatic caliper operation. Since the caliper head 25 is frustum-shaped at the end away from the sealing plate 23, the caliper head 25 has a guiding effect when entering the oil pipe, reducing the difficulty and resistance of the caliper head 25 entering the oil pipe and improving the smoothness and success rate of caliper operation.

[0030] Please see Figures 1-5This utility model provides a technical solution: the reset assembly 3 includes a pair of brackets 31, which are respectively installed on the outer wall of the air duct 22 near both ends. Each bracket 31 has an mounting cylinder 32 installed at the end furthest from the air duct 22. A take-up roller 33 is rotatably connected inside the mounting cylinder 32. A twisted rope 34 is wound around the outside of the take-up roller 33. One end of the twisted rope 34 passes through the mounting cylinder 32, the air duct 22, and the through hole 24, and is fixedly connected to the end of the through head 25 near the sealing plate 23. One end of the take-up roller 33 passes through the mounting cylinder 32 and is connected to... A turntable 35 is provided, with one side of the turntable 35 rotatably connected to the outer wall of the mounting cylinder 32. A first threaded hole is provided on the turntable 35, and a second threaded hole is provided on the mounting cylinder 32 near the first threaded hole. A bolt 36 is threaded between the first and second threaded holes. One end of the bolt 36 has an internal hexagonal groove. A pair of placement seats 12 facilitates the subsequent placement of two oil pipes to be caliped onto the placement seats 12 using hoisting equipment. After placement, the oil pipes are pushed towards one end of the sealing plate 23, causing one end of the oil pipe to engage with the sealing plate. The side of plate 23 away from the air duct 22 is tightly fitted together, and then a sealing sleeve is fitted over the end of the oil pipe away from the sealing plate 23. The tight fit between the oil pipe and the sealing plate 23 ensures that when high-pressure gas blows the caliper head 25 into the oil pipe through the through hole 24 for caliper operation, there will be no leakage from the connection between the oil pipe and the sealing plate 23. When the caliper head 25 needs to perform caliper operation, the bolt 36 is loosened and removed. At this time, the take-up roller 33 can rotate freely, allowing the caliper head 25 to perform caliper operation under the action of high-pressure gas blowing, while the winch 34 takes over the caliper. When the roller 33 is in the unwinding state, and the gauging head 25 needs to be reset after the gauging operation is completed, loosen and remove the bolt 36. The user can then manually rotate the turntable 35 to rotate the take-up roller 33 and wind up the cable 34. At this time, the first screw hole is aligned with the second screw hole again and the bolt 36 is reinstalled to prevent the take-up roller 33 from rotating on its own under the influence of external factors. This ensures that the gauging head 25 is stable in the position after reset. The internal hexagonal groove makes it easy to tighten or loosen the bolt 36 using tools such as an internal hexagonal wrench, improving the convenience and efficiency of operation.

[0031] Specifically, the working principle of this type of caliper for oil casing and anti-corrosion oil pipes is as follows: During use, two oil pipes to be caliped are placed on a pair of placement seats 12 using hoisting equipment. After placement, the oil pipes are pushed towards one end of the sealing plate 23, ensuring a tight fit between one end of the oil pipe and the side of the sealing plate 23 away from the air duct 22. Then, a sealing sleeve is fitted over the end of the oil pipe away from the sealing plate 23. When the inner diameter of the oil pipe is larger than the size of the caliper head 25, the electric telescopic rod 28 is activated, causing its movable end to retract, moving the circular plate 29. Plate 29 causes connecting rod 211 to rotate and move via first movable seat 210. The rotation and movement of connecting rod 211 are then transmitted to moving block 27 via second movable seat 212, causing moving block 27 to slide within moving groove 26, thereby changing the outer diameter of purging head 25 to adapt to different oil pipe inner diameters for purging operations. The air inlet of booster pump 213 is connected to an external air gun, and the air outlet of booster pump 213 is connected to the air inlet of air pipe 22 via a pipe. Loosen and remove bolt 36, at which point take-up roller 33 can automatically... The air blown out by the rotating air gun is pressurized by the booster pump 213 to form high-pressure gas, which enters the air duct 22 through the pipe and air inlet. Compressed air enters the air duct 22 through the air inlet, is discharged through the air outlet, and blows through the through hole 24 to move the sizing head 25 in one end of the oil pipe to achieve the sizing operation. This achieves pneumatic sizing operation. Because the sizing head 25 is frustoconical at the end away from the sealing plate 23, it has a guiding effect when entering the oil pipe, reducing the risk of the sizing head 25 entering the oil pipe. The difficulty and resistance are that the sizing head 25 performs sizing work under the action of high-pressure gas blowing, while the winding roller 33 is in an unwinding state under the action of the winch 34. When the sizing work is completed and the sizing head 25 needs to be reset, the bolt 36 is loosened and removed. The user manually rotates the turntable 35 to make the winding roller 33 rotate to wind the winch 34. At this time, the first screw hole is aligned with the second screw hole again and the bolt 36 is reinstalled to prevent the winding roller 33 from rotating on its own under the influence of external factors, and to ensure that the sizing head 25 is stable in the position after reset.

[0032] It should be noted that all standard parts used in this application can be purchased from the market, and can be customized according to the description and drawings. The specific connection methods of each part adopt conventional methods such as bolts, rivets, and welding that are mature in the prior art. The machinery, parts and equipment adopt conventional models in the prior art. Furthermore, since this application is mainly used to protect mechanical devices, the control methods and circuit connections will not be explained in detail in this application.

Claims

1. A running tool for oil casings and anticorrosive pipes, characterized in that, The assembly includes a placement component (1), a bore fitting component (2), and a reset component (3). The bore fitting component (2) is positioned above the placement component (1), and the reset component (3) is positioned outside the bore fitting component (2). The placement component (1) is used to place two oil pipes to be bored. The bore fitting component (2) is used to bore the internal diameter of the oil pipes. The reset component (3) is used to reset the bore fitting head (25). The bore fitting component (2) includes a pair of sealing plates (23), and each of the sealing plates (23) has a bore fitting head (25) on one side. The outer wall of the bore fitting head (25) has several moving grooves (26). The internal parts are equipped with sliding blocks (27). The inside of the duct head (25) is provided with a cavity. An electric telescopic rod (28) is installed on one side of the inner wall of the cavity. A circular plate (29) is installed on the movable end of the electric telescopic rod (28). Several first movable seats (210) are installed on the outer wall of the circular plate (29). A connecting rod (211) is rotatably connected to both sides of the outer side of the first movable seat (210). A pair of connecting rods (211) are rotatably connected to a second movable seat (212) at the end away from the first movable seat (210). One side of the outer wall of the second movable seat (212) is fixedly connected to one side of the sliding block (27).

2. The oil casing and anticorrosive oil pipe through path machine according to claim 1, characterized in that, Each of the two sealing plates (23) has a through hole (24) at its center, and the two sealing plates (23) have an air outlet pipe connected to the side opposite to the through head (25). The two air outlet pipes are connected to a duct (22) at the end away from the sealing plate (23), and the duct (22) has an air inlet hole.

3. The oil casing and anticorrosive oil pipe through path machine according to claim 2, characterized in that, A column (21) is installed at the bottom of the air duct (22), and a booster pump (213) is installed on one side of the outer wall of the column (21). The air outlet of the booster pump (213) is connected to the air inlet through a pipe.

4. The oil casing and anticorrosive oil pipe through path machine according to claim 1, characterized in that, The sprue head (25) is frustoconical at the end furthest from the sealing plate (23).

5. A bore gauge for oil casing and corrosion-resistant tubing according to claim 1, characterized in that, The placement assembly (1) includes a base plate (11), the upper end of which is fixedly connected to the bottom end of the column (21). A pair of placement seats (12) are installed on the base plate (11), and each pair of placement seats (12) is provided with an oil pipe. One end of each of the two oil pipes is tightly fitted to the side of the sealing plate (23) away from the air duct (22). Two through heads (25) are respectively located inside the two oil pipes near the sealing plate (23).

6. The bore gauge for oil casing and corrosion-resistant tubing according to claim 1, characterized in that, The reset assembly (3) includes a pair of brackets (31), which are respectively installed on the outer walls of the air duct (22) near both ends. Each bracket (31) has an installation cylinder (32) installed at the end away from the air duct (22). A take-up roller (33) is rotatably connected inside the installation cylinder (32). A twisted rope (34) is wound around the outside of the take-up roller (33). One end of the twisted rope (34) passes through the installation cylinder (32), the air duct (22) and the through hole (24) and is fixedly connected to the end of the through head (25) near the sealing plate (23).

7. A bore gauge for oil casing and corrosion-resistant tubing according to claim 6, characterized in that, One end of the take-up roller (33) passes through the mounting cylinder (32) and is connected to a turntable (35). One side of the turntable (35) is rotatably connected to one side of the outer wall of the mounting cylinder (32). A first screw hole is provided on the turntable (35), and a second screw hole is provided on the mounting cylinder (32) near the first screw hole. A bolt (36) is threaded between the first screw hole and the second screw hole. An internal hexagonal groove is provided inside one end of the bolt (36).

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