Screw stretcher
By introducing a pressure relief valve structure into the screw tensioner, the problem of insufficient piston upper limit control during the tensioning process is solved, thus achieving safe tensioning and reliable fastening of the screw.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- NINGBO SAIVS MACHINERY
- Filing Date
- 2025-06-30
- Publication Date
- 2026-07-07
AI Technical Summary
Existing screw tensioners cannot effectively control the upper limit of the piston during the tensioning process, which can easily lead to screw breakage or piston disengagement from the movable sleeve.
A screw tensioner was designed, comprising a support sleeve, a screw sleeve, a movable sleeve, a support cylinder, and an annular piston. The pressure relief valve structure automatically opens when the piston reaches the upper limit position to release hydraulic oil, thereby limiting the upper limit movement of the piston and the movable sleeve and preventing excessive pulling or pushing.
This effectively avoids screw breakage and piston disengagement from the moving sleeve, improving the reliability and safety of screw fastening.
Smart Images
Figure CN224464615U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of screw tensioning tools, and more specifically, to a screw tensioner. Background Technology
[0002] A screw tensioner is a device used to pull a screw so that the nut can be further tightened to the screw. Currently, Chinese Patent Publication No. CN202192414U discloses a bolt tensioner. Although this bolt tensioner can pull the bolt, it cannot control the upper limit of the piston inside during the bolt pulling process. This can easily lead to the piston pulling the bolt too much, causing the bolt to break, or the piston pushing the cover plate too much, causing the cover plate to detach from the oil cylinder. Summary of the Invention
[0003] The technical problem to be solved by this utility model is to provide a screw tensioner that can prevent the screw from breaking due to excessive tension on the screw sleeve, or prevent the piston from exerting excessive pushing force on the movable sleeve, causing the movable sleeve to detach from the piston.
[0004] This utility model provides a screw tensioner, including a support sleeve, a screw sleeve, a movable sleeve, a support cylinder, and an annular piston. The upper end of the support cylinder has an annular cavity, and an oil inlet connector communicating with the cavity is connected to the outer wall of the support cylinder. The piston is vertically slidably connected in the cavity and circumferentially sealed to the cavity. The movable sleeve is vertically movable and passes through the support cylinder, and is drivenly connected to the piston. A reset structure is provided between the movable sleeve and the support sleeve for driving the movable sleeve to move downwards and reset. The screw sleeve is vertically inserted into the movable sleeve, and its upper end abuts against the upper end of the piston. The upper end of the support sleeve is inserted into the lower end of the support cylinder and abuts against an annular step located on the inner wall of the lower end of the support cylinder. The inner side of the lower end of the support sleeve... A rotating sleeve is rotatably connected. The inner circumferential wall of the rotating sleeve forms a regular hexagonal through hole for fitting with the outer circumferential wall of the nut. Several insertion holes are provided circumferentially on the side wall of the rotating sleeve. An arc-shaped hole is provided on the side wall at the lower end of the support sleeve for the lever to pass through and slide horizontally. A pressure relief valve is connected to the inner side of the support cylinder. The oil inlet of the pressure relief valve is connected to the cavity through the first channel. An oil outlet connector is connected to the outer wall of the support cylinder. The oil outlet connector is connected to the oil outlet of the pressure relief valve through the second channel. When the movable sleeve moves to the upper limit position relative to the support cylinder with the piston, the movable sleeve triggers the pressure relief valve to open the pressure relief valve and discharge the hydraulic oil in the cavity through the first channel, the pressure relief valve, the second channel, and the oil outlet connector.
[0005] By adopting the above structure, when the movable sleeve moves to the upper limit position relative to the piston and the support cylinder, the movable sleeve can trigger the pressure relief valve to open, and the hydraulic oil in the cavity can be discharged through the first channel, the pressure relief valve, the second channel and the oil outlet connector. This can prevent the piston from moving upward continuously, that is, it can prevent the screw sleeve from causing excessive pulling on the screw and causing the screw to break, or it can prevent the piston from causing excessive pushing force on the movable sleeve and causing the movable sleeve to detach from the piston.
[0006] In one possible implementation, the pressure relief valve includes a valve seat, a valve ball, a valve stem, and a first spring; an installation cavity is provided inside the support cylinder, the valve seat is threadedly fastened in the installation cavity, the oil inlet end of the valve seat communicates with the cavity via a first channel, the oil outlet end of the valve seat communicates with the oil outlet connector via a second channel, the valve ball is disposed inside the valve seat, the valve stem is vertically movable and passes through the lower end of the valve seat and seals the valve seat circumferentially, the lower end of the valve stem extends outside the valve seat, the upper end of the valve stem abuts against the valve ball, and the lower part of the valve stem... A limiting step is provided on the wall to abut against the inner bottom of the valve seat, preventing the valve stem from disengaging from the valve seat from top to bottom. A first spring is disposed in the valve seat above the valve ball and applies a spring force to the valve ball to move it downwards and reset. When the valve stem pushes the valve ball upwards, the valve ball releases the isolation between the oil inlet and outlet ends of the valve seat, allowing the second channel to connect with the first channel. By adopting this pressure relief valve structure, when high-pressure hydraulic oil enters the oil inlet and drives the piston... When the support cylinder moves upward, the movable sleeve moves upward relative to the support cylinder along with the piston. When the movable sleeve moves to the upper limit position, it pushes the valve stem so that the valve stem pushes the valve ball upward. After the valve ball is pushed upward, it releases the isolation state between the oil inlet and outlet of the valve seat, allowing the second channel to connect with the first channel. At this time, even if hydraulic oil continuously enters the cavity through the oil inlet connector, the hydraulic oil entering the cavity will be discharged through the first channel, valve seat, second channel, and oil outlet connector, thereby limiting the continuous upward movement of the piston and movable sleeve relative to the support cylinder, which achieves the upper limit position of the piston, movable sleeve, and screw sleeve. When the hydraulic device connected to the oil inlet connector stops injecting hydraulic oil into the cavity and the hydraulic device is in the oil return state, the piston and movable sleeve can move downward relative to the support cylinder to reset under the action of the reset structure. At this time, the movable sleeve can release the pushing state of the valve stem, and the valve ball can move to reset under the action of the first spring.
[0007] In one possible implementation, a retaining ring is fitted onto the outer wall of the upper end of the movable sleeve. The outer edge of the retaining ring protrudes radially from the movable sleeve and abuts against the upper end of the piston. With this structure, when the piston moves upward relative to the support cylinder, the piston can reliably push the movable sleeve to make the movable sleeve move upward synchronously relative to the support cylinder. When the hydraulic device connected to the oil inlet stops injecting hydraulic oil into the cavity and the hydraulic device is in the oil return state, the movable sleeve can move downward relative to the support cylinder to reset under the action of the reset structure, and the piston can move downward synchronously with the movable sleeve to reset under the pushing action of the retaining ring. This ensures that the movable sleeve can be reliably connected to the piston.
[0008] In one possible implementation, the reset structure includes an annular protrusion on the outer wall of the lower end of the movable sleeve, which protrudes radially beyond the sleeve. The upper end of the annular protrusion has several guide posts spaced apart in the circumferential direction around it. The upper end of each guide post is movably inserted into the support cylinder. A second spring is sleeved on the outside of each guide post, with both ends of the second spring abutting against the support cylinder and the annular protrusion, respectively. With this reset structure, when the hydraulic device connected to the oil inlet stops injecting hydraulic oil into the cavity and is operating in the return oil state, the second spring can push the annular protrusion to move the movable sleeve downwards relative to the support cylinder to reset. Simultaneously, the piston can also move downwards relative to the support cylinder to reset. Furthermore, under the action of the guide posts, when the movable sleeve moves vertically relative to the support cylinder, the guide posts can guide the movable sleeve, improving the reliability and smoothness of its vertical movement relative to the support cylinder. Attached Figure Description
[0009] Figure 1 This is a three-dimensional structural diagram of the present invention;
[0010] Figure 2 This is a three-dimensional structural diagram of the rotating sleeve;
[0011] Figure 3 This is a cross-sectional view of the present invention after the rotating sleeve has been removed;
[0012] Figure 4 for Figure 3 A magnified structural diagram of point A in the middle. Detailed Implementation
[0013] First, those skilled in the art should understand that these embodiments are merely used to explain the technical principles of the embodiments of this application and are not intended to limit the scope of protection of the embodiments of this application. Those skilled in the art can make adjustments as needed to adapt to specific application scenarios.
[0014] In the description of the embodiments of this application, it should be noted that, unless otherwise explicitly specified and limited, the terms "connected" and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in the embodiments of this application based on the specific circumstances.
[0015] In the embodiments of this application, unless otherwise expressly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "on top of," and "over" the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.
[0016] The present application will now be described in further detail with reference to the accompanying drawings and specific embodiments.
[0017] See Figure 1-4 As shown in the embodiment of this application, a screw tensioner is disclosed, including a support sleeve 1, a screw sleeve 2, a movable sleeve 3, a support cylinder 4, and an annular piston 5. The upper end of the support cylinder 4 is provided with an annular cavity 41. An oil inlet connector 40 communicating with the cavity 41 is connected to the outer wall of the support cylinder 4. The piston 5 is vertically slidably connected in the cavity 41 and circumferentially sealed to the cavity 41. The movable sleeve 3 is vertically movable and passes through the support cylinder 4, and is connected to the piston 5 via a transmission connection. A reset structure for driving the movable sleeve 3 to move downwards and reset is provided between the movable sleeve 3 and the support sleeve 1. The screw sleeve 2 is vertically inserted into the movable sleeve 3, and its upper end abuts against the upper end of the piston 5. The upper end of the support sleeve 1 is inserted into the lower end of the support cylinder 4 and abuts against an annular step 44 located on the inner wall of the lower end of the support cylinder 4. The inner wall of the lower end of the support sleeve 1... A rotating sleeve 6 is rotatably connected to the side. The inner circumferential wall of the rotating sleeve 6 forms a regular hexagonal through hole 61 for fitting with the outer circumferential wall of the nut. Several insertion holes 62 are provided circumferentially on the side wall of the rotating sleeve 6. An arc-shaped hole 11 is provided on the side wall at the lower end of the support sleeve 1. The arc-shaped hole 11 is used for the lever to pass through and slide horizontally. A pressure relief valve 7 is connected to the inner side of the support cylinder 4. The oil inlet end of the pressure relief valve 7 is connected to the cavity 41 through the first channel 42. An oil outlet connector 8 is connected to the outer wall of the support cylinder 4. The oil outlet connector 8 is connected to the oil outlet end of the pressure relief valve 7 through the second channel. When the movable sleeve 3 moves to the upper limit position relative to the support cylinder 4 with the piston 5, the movable sleeve 3 is used to trigger the pressure relief valve 7 to open the pressure relief valve 7, so that the hydraulic oil in the cavity 41 is discharged through the first channel 42, the pressure relief valve 7, the second channel and the oil outlet connector 8.
[0018] The pressure relief valve 7 includes a valve seat 71, a valve ball 72, a valve stem 73, and a first spring 74. An installation cavity 43 is provided inside the support cylinder 4. The valve seat 71 is threadedly fastened in the installation cavity 43. The oil inlet end of the valve seat 71 communicates with the cavity 41 via a first channel 42, and the oil outlet end of the valve seat 71 communicates with the oil outlet connector 8 via a second channel. The valve ball 72 is disposed inside the valve seat 71. The valve stem 73 is vertically movable and passes through the lower end of the valve seat 71, sealing it circumferentially. The lower end of the valve stem 73 extends outside the valve seat 71, and the upper end of the valve stem 73... A limiting step 731 is provided on the lower outer wall of the valve stem 73, which abuts against the valve ball 72. The limiting step 731 abuts against the inner bottom of the valve seat 71 to prevent the valve stem 73 from disengaging from the valve seat 71 from top to bottom. A first spring 74 is provided in the valve seat 71 located above the valve ball 72 and is used to apply a spring force to the valve ball 72 to drive it to move downward and reset. When the valve stem 73 pushes the valve ball 72 upward, the valve ball 72 is used to release the isolation state between the oil inlet and oil outlet of the valve seat 71 so that the second channel is connected to the first channel 42. By adopting this pressure relief valve structure, when high-pressure hydraulic oil enters the inlet connector and drives the piston to move upward relative to the support cylinder, the movable sleeve can move upward with the piston relative to the support cylinder. When the movable sleeve moves upward to the upper limit position, it can push the valve stem so that the valve stem pushes the valve ball upward. After the valve ball is pushed upward, it can release the isolation state between the inlet and outlet ends of the valve seat, so that the second channel is connected to the first channel. At this time, even if hydraulic oil continues to enter the cavity through the inlet connector, the hydraulic oil entering the cavity will be discharged through the first channel, the valve seat, the second channel, and the outlet connector, thereby limiting the continuous upward movement of the piston and movable sleeve relative to the support cylinder, which achieves the upper limit position of the piston, movable sleeve, and screw sleeve. When the hydraulic device connected to the inlet connector stops injecting hydraulic oil into the cavity and the hydraulic device is working in the return oil state, the piston and movable sleeve can move downward relative to the support cylinder to reset under the action of the reset structure. At this time, the movable sleeve can release the pushing state of the valve stem, and the valve ball can move to reset under the action of the first spring.
[0019] A retaining ring 9 is fitted on the outer wall of the upper end of the movable sleeve 3. The outer edge of the retaining ring 9 protrudes radially from the movable sleeve 3 and abuts against the upper end of the piston 5. With this structure, when the piston moves upward relative to the support cylinder, the piston can reliably push the movable sleeve so that the movable sleeve moves upward synchronously relative to the support cylinder. When the hydraulic device connected to the oil inlet stops injecting hydraulic oil into the cavity and the hydraulic device is in the oil return state, the movable sleeve can move downward relative to the support cylinder to reset under the action of the reset structure, and the piston can move downward synchronously with the movable sleeve to reset under the pushing action of the retaining ring. This means that the movable sleeve can be reliably connected to the piston.
[0020] The reset structure includes an annular protrusion 31 on the outer wall of the lower end of the movable sleeve 3, which protrudes radially from the movable sleeve 3. Several guide posts 32 are spaced apart around the annular protrusion 31 in the circumferential direction at the upper end of the annular protrusion 31. The upper end of each guide post 32 is movably inserted into the support cylinder 4. A second spring 33 is sleeved on the outside of each guide post 32, with both ends of the second spring 33 abutting against the support cylinder 4 and the annular protrusion 31, respectively. With this reset structure, when the hydraulic device connected to the oil inlet stops injecting hydraulic oil into the cavity and the hydraulic device is in the return oil state, the second spring can push the annular protrusion to move the movable sleeve downwards relative to the support cylinder to reset. Simultaneously, the piston can also move downwards relative to the support cylinder to reset. Furthermore, under the action of the guide posts, when the movable sleeve moves vertically relative to the support cylinder, the guide posts can guide the movable sleeve, thereby improving the reliability and smoothness of the vertical movement of the movable sleeve relative to the support cylinder.
[0021] When using this invention, firstly, the upper end of the screw located on the object to be fastened passes through the support sleeve and is threadedly connected to the sleeve, while the lower end of the support sleeve abuts against the object to be fastened. Simultaneously, the nut pre-threaded onto the screw engages with the through hole on the rotating sleeve located inside the support sleeve. Then, the hydraulic device injects high-pressure hydraulic oil into the cavity through the oil inlet connector. At this time, the piston can drive the movable sleeve and the sleeve to move upwards relative to the support cylinder synchronously, meaning the sleeve can pull the screw upwards. When the screw is pulled upwards and experiences a certain stretch, the rotating sleeve is driven to move the screw located on the support sleeve by engaging the lever with the insertion holes at different positions and by sliding the lever in the arc-shaped hole. The nut on the screw rotates, eventually pressing against the object to be tightened, thus securing the nut and bolt. Then, the hydraulic system stops injecting hydraulic oil into the cavity and switches to return oil mode. At this point, the piston and movable sleeve can move downwards relative to the support cylinder under the action of the reset structure, and the piston can release its pushing force on the screw sleeve. After the screw sleeve loses the piston's pushing force, the previously stretched screw can contract, further securing the nut against the object to be tightened, thereby improving the reliability of the screw and nut in tightening the object. Finally, the screw sleeve is unscrewed from the screw, and the support cylinder, movable sleeve, and support sleeve are removed from the screw.
[0022] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.
Claims
1. A screw tensioner, comprising a support sleeve (1), a screw sleeve (2), a movable sleeve (3), a support cylinder (4), and an annular piston (5); the upper end of the support cylinder (4) is provided with an annular cavity (41), an oil inlet connector (40) communicating with the cavity (41) is connected to the outer wall of the support cylinder (4), the piston (5) is vertically slidably connected in the cavity (41) and circumferentially sealed to the cavity (41), the movable sleeve (3) is vertically movable and passes through the support cylinder (4) and is drivenly connected to the piston (5), a reset structure for driving the movable sleeve (3) to move downward and reset is provided between the movable sleeve (3) and the support sleeve (1), the screw sleeve (2) vertically... The upper end of the screw sleeve (2) inserted into the movable sleeve (3) abuts against the upper end of the piston (5). The upper end of the support sleeve (1) is inserted into the lower end of the support cylinder (4) and abuts against the annular step (44) on the inner wall of the lower end of the support cylinder (4). A rotating sleeve (6) is rotatably connected to the inner side of the lower end of the support sleeve (1). The inner circumferential wall of the rotating sleeve (6) forms a through hole (61) in the shape of a regular hexagon for fitting with the outer circumferential wall of the nut. Several insertion holes (62) are arranged circumferentially on the side wall of the rotating sleeve (6). An arc-shaped hole (11) is provided on the side wall of the lower end of the support sleeve (1). The arc-shaped hole (11) is used for the lever to pass through and slide horizontally. The characteristic of the support sleeve (1) is: The inner side of the support cylinder (4) is connected to a pressure relief valve (7). The oil inlet of the pressure relief valve (7) is connected to the cavity (41) through the first channel (42). The outer wall of the support cylinder (4) is connected to an oil outlet connector (8). The oil outlet connector (8) is connected to the oil outlet of the pressure relief valve (7) through the second channel. When the movable sleeve (3) moves to the upper limit position relative to the support cylinder (4) with the piston (5), the movable sleeve (3) is used to trigger the pressure relief valve (7) to open the pressure relief valve (7) and allow the hydraulic oil in the cavity (41) to be discharged through the first channel (42), the pressure relief valve (7), the second channel and the oil outlet connector (8).
2. The screw tensioner according to claim 1, characterized in that: The pressure relief valve (7) includes a valve seat (71), a valve ball (72), a valve stem (73), and a first spring (74); the inner side of the support cylinder (4) is provided with an installation cavity (43), the valve seat (71) is threadedly fastened in the installation cavity (43), the oil inlet end of the valve seat (71) is connected to the cavity (41) through the first channel (42), the oil outlet end of the valve seat (71) is connected to the oil outlet connector (8) through the second channel, the valve ball (72) is disposed inside the valve seat (71), the valve stem (73) is vertically movable and passes through the lower end of the valve seat (71) and is circumferentially sealed to the valve seat (71), the lower end of the valve stem (73) extends out of the valve seat (71), the valve... The upper end of the rod (73) abuts against the valve ball (72). A limiting step (731) is provided on the outer wall of the lower part of the valve rod (73). The limiting step (731) is used to abut against the inner bottom of the valve seat (71) to prevent the valve rod (73) from disengaging from the valve seat (71) from top to bottom. The first spring (74) is provided in the valve seat (71) located above the valve ball (72) and is used to apply a spring force to the valve ball (72) to drive the valve ball (72) to move downward and reset. When the valve rod (73) pushes the valve ball (72) upward, the valve ball (72) is used to release the isolation state between the oil inlet end and the oil outlet end of the valve seat (71) so that the second channel is connected to the first channel (42).
3. The screw tensioner according to claim 1 or 2, characterized in that: A retaining ring (9) is fitted on the outer wall of the upper end of the movable sleeve (3). The outer edge of the retaining ring (9) protrudes radially from the movable sleeve (3) and abuts against the upper end of the piston (5).
4. The screw tensioner according to claim 1 or 2, characterized in that: The reset structure includes an annular protrusion (31) on the outer wall of the lower end of the movable sleeve (3) and protruding radially out of the movable sleeve (3). The upper end of the annular protrusion (31) is provided with a plurality of guide posts (32) that are spaced apart around the annular protrusion (31) in the circumferential direction. The upper end of each guide post (32) is movably inserted into the support cylinder (4). A second spring (33) is sleeved on the outside of each guide post (32). The two ends of the second spring (33) abut against the support cylinder (4) and the annular protrusion (31) respectively.