Double-helix bolt tensioner

Abstract

A double-helix bolt tensioner relates to the tool industry, and is shown in the attached drawing and mainly composed of a nut tensioning wrench 1, a speed reduction and non-return mechanism 2, a torque wrench 3, a nut tensioning 4, an inner gear ring sleeve 5, a rotating disc 6, a lower seat 7, a nut locking mechanism 8, a nut 9 of a tensioned bolt, the tensioned bolt 10, an upper flange 11 and a lower flange 12. The mechanical bolt tensioner is characterized in that a single-face ball screw of a rotary table in an existing mechanical bolt tensioner is changed into a double-face ball screw with an upper face and a lower face symmetrical, so that fatigue fracture caused by unbalanced stress of the upper face and the lower face of the rotary table is eliminated, meanwhile, the one-time maximum stretching length of the tensioner is doubled, and two purposes are achieved at a time.

Description

Technical Field

[0001] This utility model relates to an improvement of bolt tensioners in the tool industry. Background Technology

[0002] Nowadays, when tightening large-diameter bolts, a bolt tensioner must be used to ensure that the bolt tension is accurately achieved. Figure 1 This is a simplified structural diagram of a current mechanical bolt tensioner. The mechanical bolt tensioner mainly consists of 1-tensioning nut wrench, 2-reduction and backstop mechanism, 3-torque wrench, 4-tensioning nut, 5-internal gear ring, 6-turntable, 7-lower seat, and 8-locking nut mechanism. The upper part of the turntable has a flat ball structure, while the lower part has a helical ball structure. 9 is the nut of the bolt being tensioned, 10 is the bolt being tensioned, 11 is the upper flange, and 12 is the lower flange. The tensioner operates as follows: First, place the tensioner onto the bolt to be tensioned. Then, use a tensioning nut wrench to turn the tensioning nut clockwise until it is tightened onto the bolt. Next, insert a torque wrench into the central gear of the reduction and backstop mechanism and turn it clockwise. At this time, the internal gear ring will rotate the turntable counterclockwise. Under the action of the ball bearing spiral at the bottom of the turntable, the tensioning nut is gradually lifted as the turntable rotates, thus tensioning the bolt. Once the bolt tension reaches the target, immediately turn the locking nut mechanism wrench counterclockwise to rotate the nut of the tensioned bolt, locking the bolt's elastic elongation. At this time, the upper and lower flanges will be pressed tightly by the bolt's elastic force. Finally, pull out the torque wrench, open the backstop mechanism, and let the turntable rotate back to its initial position. Then, turn the tensioning nut wrench counterclockwise to remove the tensioner. This completes the operation. Two problems were found during the use of this tensioner: First, the turntable is prone to fatigue fracture shortly after use, with the fracture surface appearing on the... Figure 1 Point C on the turntable, based on analysis, is most likely caused by an imbalance of forces between the upper and lower surfaces of the turntable. (See attached image) Figure 1 and attached Figure 2 Above the turntable, the raceway is filled with balls, while below, there is a nearly 90-degree circumferential area on the helical raceway without ball support. Since the tensile force of the bolts can reach tens or even hundreds of tons, fatigue fracture is likely to occur at point C. The second problem is that the maximum tensile length of this tensioner is limited. This maximum tensile length depends on the maximum rotation angle of the turntable and the pitch of the helical raceway. (From the attached...) Figure 2 It can be seen that the maximum rotation angle of the turntable is 2a, and it cannot be increased further. The only way is to increase the pitch. Figure 2 In the middle: 13 is the helical surface, 14 is the helical groove, and in the appendix... Figure 3 In the diagram: s is the pitch, d is the ball diameter, c is the helical groove depth, and e is the minimum clearance between the upper and lower helical surfaces. Figure 3As can be seen from this, the pitch s = d - 2c - e. Obviously, once the ball diameter d and the groove depth c are determined, the increase in pitch s is also limited. Summary of the Invention

[0003] The purpose of this invention is to provide a double-helix bolt tensioner. In existing mechanical bolt tensioners, the upper part of the turntable is also made into a ball helix that is symmetrical to its lower part. In this way, the balls on the upper and lower parts of the turntable are symmetrically distributed, effectively solving the problem of unbalanced force on the upper and lower parts. At the same time, since the upper part of the turntable also has the same helical lifting function as its lower part, the improved tensioner doubles the maximum tension length in one pass, thus solving the problem of insufficient maximum tension length in one pass.

[0004] The technical solution adopted by this utility model to solve the technical problem is: a double helical bolt tensioner, mainly composed of a deceleration and backstop mechanism located at the upper part, a ball helical mechanism located in the middle part, and a locking nut mechanism located at the lower part. Its feature is that the ball helical mechanism in the middle part is composed of two mutually symmetrical ball helical mechanisms located above and below the turntable.

[0005] The beneficial effects of this utility model are as follows: the double-helix bolt tensioner composed of the deceleration and backstop mechanism, the ball screw mechanism and the locking nut mechanism with the above-mentioned features, compared with the existing mechanical bolt tensioner, has eliminated fatigue fracture caused by the imbalance of forces on the upper and lower surfaces of the turntable by changing the single-sided helix of the turntable to a double-sided helix with symmetrical upper and lower surfaces. At the same time, it doubles the maximum tension length of the tensioner in one go, achieving two benefits in one go. Attached Figure Description

[0006] Appendix Figure 1 This is a simplified structural diagram of a current mechanical bolt tensioner.

[0007] Appendix Figure 2 It is attached Figure 1 A cross-sectional view of plane AA.

[0008] Appendix Figure 3 It is attached Figure 1 Enlarged view of point B in the middle.

[0009] Appendix Figure 4 This is a simplified structural diagram of the present invention. Detailed Implementation

[0010] Appendix Figure 4This is a preferred embodiment of the present invention, which mainly consists of: 1-tensioning nut wrench, 2-deceleration and backstop mechanism, 3-torque wrench, 4-tensioning nut, 5-internal gear ring, 6-turntable, 7-lower seat, and 8-locking nut mechanism to form a double helical bolt tensioner. The upper part of the turntable and the tensioning nut form an upper ball helix, while the lower part of the turntable and the lower seat form a lower ball helix. 9 is the nut of the bolt being tensioned, 10 is the bolt being tensioned, 11 is the upper flange, and 12 is the lower flange. The tensioner operates as follows: First, place the tensioner onto the bolt to be tensioned. Then, use a tensioning nut wrench to turn the tensioning nut clockwise until it is tightened onto the bolt. Next, insert a torque wrench into the central gear of the reduction and backstop mechanism and turn it clockwise. At this time, the internal gear ring will rotate the turntable counterclockwise. Under the action of the upper and lower ball screws on the turntable, the tensioning nut is gradually lifted as the turntable rotates, thus tensioning the bolt. After the bolt tension reaches the target, immediately turn the locking nut mechanism wrench counterclockwise to rotate the nut of the tensioned bolt to lock the bolt's elastic elongation. At this time, the upper and lower flanges will be pressed tightly by the bolt's elastic force. Finally, pull out the torque wrench, open the backstop mechanism, and let the turntable rotate back to the initial position. Then, turn the tensioning nut wrench counterclockwise to remove the tensioner. The entire operation is now complete.

Claims

1. A double helix bolt tensioner, mainly composed of a speed reduction and non-return mechanism located at the upper part, a ball screw mechanism located at the middle part and a locking nut mechanism located at the lower part, characterized in that: The middle ball screw mechanism is composed of two mutually symmetrical ball screw mechanisms located above the rotary disc and below the rotary disc. The middle ball screw mechanism is composed of two mutually symmetrical ball screw mechanisms located above the rotary disc and below the rotary disc.

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