Precise tensioning jack for whole bundle of prestressed steel strands
By introducing a combination design of pre-pull small top and tension large top in the jack, we ensure that each steel strand bears uniform tension during the entire bundle tensioning process, solving the unevenness caused by inconsistent slack length in the prior art The stress problem improves the tensioning quality and safety.
Patent Information
- Application Number
- CN202411765327.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-04
- Publication Date
- 2025-01-07
AI Technical Summary
During the tensioning process of the entire steel strand wire, the existing penetrating jacks have uneven tensioning forces due to inconsistent slack lengths in the hole, which is prone to fracture and safety accidents, and the tensioning quality is not satisfactory. Standardization requirements cause waste.
A complete bunch of prestressed steel stranded wire precision tension jacks including tensioned large tops and pre-pull small tops were designed. Each steel strand is initially tensioned by pre-pull small tops, and a large top pair is tensioned by tensioning large tops. All pre-pull small tops are uniformly stretched to ensure that each steel strand is subjected to the same tension and tension at the same amount of tension, and precise control is achieved using adjustment screws.
The force uniformity of each steel strand is achieved, the tensioning quality and safety are improved, the fracture and waste caused by inconsistent slack lengths are avoided, and the specifications are met.
Smart Images
Figure CN119263143A_ABST
Abstract
Description
Technical Field
[0001] The invention belongs to the technical field of civil engineering construction, and in particular relates to a precise tensioning jack for a whole bundle of prestressed steel strands. Background Art
[0002] The existing through-type jack uses the form of tensioning the entire bundle of steel strands. From the installation of the tool anchor to the end of tensioning, the tensioning length of each steel strand is the same. Since the steel strand holes are mostly in the form of vertical curves, the hole radius is large, there are many bending points in the hole, and the hole conditions are complicated after the hole is squeezed by concrete, resulting in inconsistent relaxation lengths of the steel strands in the hole. When the entire bundle is tensioned, under the condition of the same tensioning elongation, the tensioning force borne by each steel strand is different, among which: the steel strand with a short relaxation length in the hole is subjected to force the earliest during tensioning, and the tensioning stress is the largest after tensioning is completed; the steel strand with a long relaxation length in the hole is subjected to force the latest during tensioning, and the tensioning stress is the smallest after tensioning is completed.
[0003] The hazards of uneven force on each strand in the whole bundle of steel strands: ① The steel strands with greater force are prone to breakage, and the tensioning quality does not meet the requirements of the specifications, resulting in rework; ② The steel strands are relatively fragile, and the tensioned steel strands are marked by the conical clamps. They are more likely to break after repeated tensioning. They are generally discarded, causing waste; ③ The strands are prone to breakage and wire breakage during the tensioning process. The broken steel strands are prone to popping out and causing safety accidents, seriously affecting the tensioning operation and the safety of surrounding personnel. Summary of the invention
[0004] In view of this, the object of the present invention is to provide a precise tensioning jack for a whole bundle of prestressed steel strands, which can solve the above-mentioned technical problems.
[0005] In order to achieve the above object, the present invention provides the following technical solutions: The present invention discloses a precision tensioning jack for a whole bundle of prestressed steel strands, comprising a tensioning big top body and a jack base installed at one end of the tensioning big top body, a big top piston cavity is formed on the inner side of the tensioning big top body, a big top piston is installed in the big top piston cavity with a sliding seal, the big top piston divides the big top piston cavity into a tensioning oil cylinder and a big return oil cylinder, the tensioning oil cylinder and the big return oil cylinder are respectively connected with a tensioning oil nozzle and a big return oil nozzle, the outer end of the big top piston extends toward the end away from the jack base, and adjusting screws are evenly installed on the upper edge of the outer end surface of the big top piston in the circumferential direction, the outer end of the adjusting screw is rotatably connected to a pre-tensioned small top through a tail seat, and the axis of the pre-tensioned small top is parallel to the axis of the tensioning big top body.
[0006] Furthermore, the pre-tensioned small top includes a pre-tensioned small top body, a small top piston, a small top piston rod and a pre-tensioned clamping assembly, the tail stock is installed at one end of the pre-tensioned small top body, a small top piston cavity is formed on the inner side of the pre-tensioned small top body, a small top piston is installed in the small top piston cavity in a sliding seal, the small top piston divides the small top piston cavity into a pre-tensioning cylinder and a small return cylinder, the pre-tensioning cylinder and the small return cylinder are respectively connected with a pre-tensioning oil nozzle and a small-large return oil nozzle; the outer end of the small top piston extends toward the end away from the tail stock and is connected to the small top piston rod, and a pre-tensioning clamping assembly for clamping the steel strand is installed on the inner side of the small top piston rod.
[0007] Furthermore, the pre-tensioning clamping assembly includes a center piston, a sleeve, and a conical clip. The center piston is slidably arranged on the inner side of the small top piston. One end of the center piston is connected to the sleeve. A plurality of conical clips are evenly distributed axially at the center of the sleeve. A conical surface that cooperates with the conical clip is formed on the inner side of the sleeve. A center cavity is formed between the center piston and the small top piston, and a channel is provided on the small top piston to connect the center cavity and the pre-tensioning cylinder.
[0008] Furthermore, one end of the central piston is connected to a first spring, and the first spring is connected to a support ring away from the central piston, and the support ring is in contact with the end surface of the conical clip.
[0009] Furthermore, the outer end of the small top piston rod is spherically hinged with a protective sleeve, a limiting plate is fixed to the outer side of the small top piston rod, a second spring is connected between the protective sleeve and the limiting plate, and the second spring sleeve is arranged on the outer side of the small top piston rod.
[0010] Furthermore, a center hole is opened in the center of the protective sleeve, and a rubber sleeve is installed at the center hole.
[0011] Furthermore, a rotating ring is installed on the outer side of the tailstock, and a ring groove cooperating with the rotating ring is opened on the end surface of the pre-tensioned small top body.
[0012] The beneficial effects of the present invention are: The present invention discloses a precise tensioning jack for a whole bundle of prestressed steel strands. Each steel strand can be tensioned first through each pre-tensioning small top, and then all the pre-tensioning small tops are tensioned through the tensioning big top, thereby avoiding the problem of inconsistent relaxation lengths of the steel strands in the channel. When the whole bundle is tensioned, under the condition of the same tensioning elongation, the tensioning force borne by each steel strand is the same, the force is more uniform, the tensioning quality meets the requirements, and the tensioning is safer.
[0013] In the device disclosed in the present invention, the outer end of the adjusting screw is rotatably connected to the pre-tensioning pin through the tailstock, so the pre-tensioning length can be fine-tuned by rotating the adjusting screw, further ensuring that the tensioning quality meets the requirements, lowering the quality control requirements, and achieving precise control of the tensioning.
[0014] Other advantages, objectives and features of the present invention will be described in the following description and will be apparent to those skilled in the art to some extent, or those skilled in the art may be taught from the practice of the present invention. The objectives and other advantages of the present invention may be realized and obtained through the following description. BRIEF DESCRIPTION OF THE DRAWINGS
[0015] In order to make the purpose, technical solution and beneficial effects of the present invention clearer, the present invention provides the following drawings for illustration: Figure 1 It is a structural schematic diagram of the tensioning jack of the present invention; Figure 2 for Figure 1 A magnified view at point A; Figure 3 This is a structural schematic diagram of a pre-tensioned small roof; Figure 4 It is a schematic diagram of the structure of the tapered clip; Figure 5 This is a schematic diagram of the fuel supply control.
[0016] The markings in the accompanying drawings are as follows: tensioning big top body 1, jack base 2, big top piston 3, tensioning cylinder 4, big return top cylinder 5, tensioning oil nozzle 6, big return top nozzle 7, adjusting screw 8, tail stock 9, pre-tensioning small top 10, pre-tensioning small top body 11, small top piston 12, small top piston rod 13, pre-tensioning cylinder 14, small return top cylinder 15, pre-tensioning oil nozzle 16, small and large return top nozzle 17, center piston 18, jacket 19, conical clip 20, center cavity 21, first spring 22, support ring 23, protective cover 24, limit plate 25, second spring 26, center hole 27, rubber sleeve 28, rotating ring 29, ring groove 30, channel 31. DETAILED DESCRIPTION
[0017] like Figures 1 to 5 As shown, the present invention discloses a precise tensioning jack for a whole bundle of prestressed steel strands, comprising a tensioning top body 1 and a jack base 2 installed at one end of the tensioning top body 1, the jack base 2 is used to support the whole, the tensioning top body 1 is arranged horizontally, and the tail end of the jack base 2 is connected to the main bearing structure of the jack, which can provide stable reaction force support for the tensioning process.
[0018] Among them, a large top piston cavity is formed on the inner side of the tensioning large top body 1, and a large top piston 3 is installed in the large top piston cavity in a sliding seal. The large top piston 3 divides the large top piston cavity into a tensioning cylinder 4 and a large return cylinder 5. The tensioning cylinder 4 faces the side where the jack base 2 is located. The tensioning cylinder 4 and the large return cylinder 5 are respectively connected to a tensioning oil nozzle 6 and a large return oil nozzle 7. When the tensioning oil nozzle 6 discharges oil and the large return oil nozzle 7 intakes oil, under the action of oil pressure, the large top piston 3 is displaced toward the side where the jack base 2 is located, thereby realizing the tension of the entire bundle of steel strands and facilitating overall control.
[0019] Specifically, the outer end of the large top piston 3 of the present invention extends toward the end away from the jack base 2, and 6 groups of adjusting screws 8 are evenly installed along the circumferential direction on the outer end surface of the large top piston 3. The 6 groups of adjusting screws 8 are distributed on the same concentric circle with the axis of the large top piston 3 as the center. The outer end of the adjusting screw 8 is rotatably connected to the pre-tensioned small top 10 through the tail seat 9. The axis of the pre-tensioned small top 10 is parallel to the axis of the tensioning large top body 1, so that the consistency of the tensioning direction is achieved. In the device disclosed in the present invention, each steel strand is first tensioned by the pre-tensioned small top 10, and then all the pre-tensioned small tops 10 are tensioned by the tensioning large top, thereby avoiding the problem of inconsistent relaxation length of the steel strands in the channel. When the whole bundle is tensioned, under the condition of the same tensioning elongation, each steel strand is subjected to the same tensioning force, and the force is more uniform, so that the tensioning quality meets the requirements and the tensioning is safer.
[0020] The prestressed steel strand adopts high strength and low relaxation, with a nominal diameter of φ15.2. Its tensile strength is 1860MPa and its elastic modulus is Ep=1.95×10 5 MPa. Steel strands, anchors, clamps, etc. shall be inspected according to the design and specification requirements after they arrive at the site.
[0021] Before tensioning, the device of the present invention uses a grinder to cut the steel strands. Electric welding and oxygen cutting are strictly prohibited. Before cutting, tie 5 cm on both sides of the fracture with wire to prevent the cut from loosening during cutting. Pay attention to reserving a certain working length when cutting. Straighten each steel wire and tie it with wire every 1.5 m. Keep the order of the steel strand heads at both ends consistent, and tie the bundle end into a pointed cone. Wrap the bundle end tightly with tape, insert the steel strand bundle into the corrugated pipe, and the exposed lengths at both ends are the same. Install anchors and clips, and tighten the clips. The same pair of clips must be flush, and the two gaps must be equal in width.
[0022] Tensioning is carried out when the concrete strength and elastic modulus of the beam body reach 90% of the design strength and the concrete age is not less than 7 days. Tensioning is used to control both stress and elongation, with stress control as the main method. The error between the actual elongation and the design value is controlled within ±6%. The tensioning sequence is from bottom to top, symmetrical on both sides, and tensioning is done synchronously at both ends.
[0023] Figure 5 Schematic diagram of oil supply control. The oil supply is controlled by the distribution valve. The tensioning steps are: 0→pre-tensioning jacks tension each bundle to the initial tensioning tonnage (10%σk)→tensioning jacks tension the entire bundle to 100%σk tensioning tonnage→hold load for 5 minutes→anchor.
[0024] The tensioning force of the pre-tensioning jack (10% of the tensioning force) is to tighten the relaxed prestressed steel strands one by one. At this time, marks are accurately marked at both ends of the tensioning jack. The extension or retraction of the prestressed steel strand is measured from the mark. The readings of the tensioning force and extension are read in stages during the tensioning process. The actual elongation value ΔL of the prestressed steel strand, in addition to the above-mentioned measured elongation value, should be added with the estimated elongation value at the initial stress, that is: ΔL=ΔL1+ΔL2 Where ΔL1 is the measured value from the initial tension to the maximum tension; ΔL2 is the estimated elongation value at the initial tension, and the elongation of the adjacent level is generally used; The difference between the measured elongation and the calculated elongation should be within ±6%. Otherwise, the cause should be analyzed and the following steps should be taken: recalibrate the equipment; conduct elastic modulus test on prestressed steel strands; use lubricants on prestressed steel strands to reduce friction loss; measure the retraction of prestressed steel strands and the deformation of anchors. The value should not be greater than 6mm. If it is greater than 6mm, re-tensioning should be done or re-tensioning after replacing the anchors. No more than 1 wire should be broken or slipped in each bundle of steel strands; the sum of broken wires in each section should not exceed 1% of the total number of steel wires in that section.
[0025] In this embodiment, the pre-stretched small top 10 includes a pre-stretched small top body 11, a small top piston 12, a small top piston rod 13 and a pre-stretched clamping assembly. The tail stock 9 is installed at one end of the pre-stretched small top body 11. The tail stock 9 rotates with the pre-stretched small top body 11, and the pre-stretched small top body 11 will not affect the rotation.
[0026] Similarly, a small top piston cavity is formed on the inner side of the pre-tensioned small top body 11, and a small top piston 12 is installed in the small top piston cavity in a sliding seal. The small top piston 12 divides the small top piston cavity into a pre-tensioning cylinder 14 and a small return cylinder 15. The pre-tensioning cylinder 14 is located on the side close to the tail stock 9, and the pre-tensioning cylinder 14 and the small return cylinder 15 are respectively connected with a pre-tensioning nozzle 16 and a small-large return nozzle 17; the outer end of the small top piston 12 extends toward the end away from the tail stock 9 and is connected to the small top piston rod 13, and a pre-tensioning clamping assembly for clamping the steel strand is installed on the inner side of the small top piston rod 13.
[0027] The pre-tensioning clamping assembly is used to clamp the steel strand. When in use, the pre-tensioning cylinder 14 discharges oil, and the small return cylinder 15 receives oil. After the small return piston 12 moves, it drives the small return piston rod 13 and the pre-tensioning clamping assembly to move toward the side where the tailstock 9 is located, thereby pre-tensioning the steel strand in the pre-tensioning clamping assembly.
[0028] In this embodiment, the pre-tensioning clamping assembly includes a central piston 18, a jacket 19, and a conical clip 20. The central piston 18 is slidably arranged on the inner side of the small top piston 12. One end of the central piston 18 is connected to the jacket 19. A number of conical clips 20 are evenly distributed along the axial direction at the center of the jacket 19. A conical surface that cooperates with the conical clips 20 is formed on the inner side of the jacket 19. A central cavity 21 is formed between the central piston 18 and the small top piston 12. A channel 31 that connects the central cavity 21 and the pre-tensioning cylinder 14 is provided on the small top piston 12. When the pre-tensioning cylinder 14 discharges oil, negative pressure is also generated in the central cavity 21, which can drive the central piston 18 to move toward the side where the base is located. At this time, the central piston 18 drives the jacket 19 to move to the left. The jacket 19 can drive each conical clip 20 to move toward the center with the cooperation of the conical surface to clamp the steel strand, which can play an automatic clamping role and save the clamping steps of the steel strand.
[0029] In this embodiment, one end of the center piston 18 is connected to a first spring 22, and the first spring 22 is connected to a support ring 23 away from the center piston 18, and the support ring 23 contacts the end surface of the tapered clip 20. Similarly, when the center piston 18 moves in the reverse direction, the jacket 19 loosens the tapered clip 20, and the tapered clip 20 can move radially outward under the support of the first spring 22, and the tapered clip 20 loosens the steel strand, which can be more conducive to taking out the steel strand.
[0030] In this embodiment, the outer end of the small top piston rod 13 is spherically hinged with a protective sleeve 24, a limit plate 25 is fixed to the outer side of the small top piston rod 13, a second spring 26 is connected between the protective sleeve 24 and the limit plate 25, and the second spring 26 is sleeved on the outer side of the small top piston rod 13. By providing the second spring 26, when the steel strand is eccentric, the steel strand can drive the protective sleeve 24 to deflect, and after the protective sleeve 24 rotates, the second spring 26 can provide elastic buffering for the protective sleeve 24, thereby reducing the damage of the protective sleeve 24 caused by rigid deflection.
[0031] In this embodiment, a center hole 27 is opened in the center of the protective cover 24, and a rubber cover 28 is installed at the center hole 27 to avoid the protective cover 24 or the steel strand from being damaged due to direct contact between the center hole 27 and the steel strand, thereby protecting the central steel strand.
[0032] In this embodiment, a rotating ring 29 is installed on the outer side of the tailstock 9, and a ring groove 30 cooperating with the rotating ring 29 is opened on the end surface of the pre-tensioned small top body 11, which can adapt to the axial movement of the rotating ring 29 and play a guiding and sealing role.
[0033] Finally, it should be noted that the above preferred embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail through the above preferred embodiments, those skilled in the art should understand that various changes can be made in form and details without departing from the scope defined by the claims of the present invention.
Claims
1. A precision tensioning jack for a whole bundle of prestressed steel strands, characterized in that: It includes a tensioning big top body and a jack base installed at one end of the tensioning big top body, a big top piston cavity is formed on the inner side of the tensioning big top body, a big top piston is installed in the big top piston cavity with a sliding seal, the big top piston divides the big top piston cavity into a tensioning oil cylinder and a big return oil cylinder, the tensioning oil cylinder and the big return oil cylinder are respectively connected with a tensioning oil nozzle and a big return oil nozzle, the outer end of the big top piston extends toward the end away from the jack base, and adjusting screws are evenly installed on the upper edge of the outer end surface of the big top piston in the circumferential direction, the outer end of the adjusting screw is rotatably connected with a pre-tensioned small top through a tail seat, and the axis of the pre-tensioned small top is parallel to the axis of the tensioning big top body.
2. The precise tensioning jack for a whole bundle of prestressed steel strands according to claim 1, characterized in that: The pre-tensioned small top includes a pre-tensioned small top body, a small top piston, a small top piston rod and a pre-tensioned clamping assembly. The tailstock is installed at one end of the pre-tensioned small top body. A small top piston cavity is formed on the inner side of the pre-tensioned small top body. A small top piston is installed in the small top piston cavity in a sliding seal. The small top piston divides the small top piston cavity into a pre-tensioned oil cylinder and a small return oil cylinder. The pre-tensioned oil cylinder and the small return oil cylinder are respectively connected with a pre-tensioned oil nozzle and a small-large return oil nozzle; the outer end of the small top piston extends toward the end away from the tailstock and is connected to the small top piston rod. A pre-tensioned clamping assembly for clamping the steel strand is installed on the inner side of the small top piston rod.
3. The precise tensioning jack for a whole bundle of prestressed steel strands according to claim 2, characterized in that: The pre-tensioning clamping assembly includes a center piston, a sleeve, and a conical clip. The center piston is slidably arranged on the inner side of the small top piston. One end of the center piston is connected to the sleeve. A plurality of conical clips are evenly distributed axially at the center of the sleeve. A conical surface that cooperates with the conical clip is formed on the inner side of the sleeve. A center cavity is formed between the center piston and the small top piston. A channel that connects the center cavity and the pre-tensioning cylinder is opened on the small top piston.
4. The precise tensioning jack for a whole bundle of prestressed steel strands according to claim 3, characterized in that: One end of the central piston is connected to a first spring, and the first spring is connected to a support ring away from the central piston, and the support ring is in contact with the end surface of the conical clip.
5. The precise tensioning jack for a whole bundle of prestressed steel strands according to claim 2, characterized in that: The outer end of the small top piston rod is spherically hinged with a protective sleeve, a limit plate is fixed on the outer side of the small top piston rod, a second spring is connected between the protective sleeve and the limit plate, and the second spring sleeve is arranged on the outer side of the small top piston rod.
6. The precise tensioning jack for a whole bundle of prestressed steel strands according to claim 5, characterized in that: A central hole is provided at the center of the protective sleeve, and a rubber sleeve is installed at the central hole.
7. A precision tensioning jack for a whole bundle of prestressed steel strands according to any one of claims 1 to 6, characterized in that: A rotating ring is installed on the outer side of the tailstock, and a ring groove matching with the rotating ring is opened on the end surface of the pre-tensioned small top body.