Mechanical bolt tensioner

Abstract

The invention relates to a mechanical bolt tensioner in the tool industry, which is shown in the figure and mainly comprises a manual torque wrench 1, a speed reducing mechanism 2, a stretching nut 3, an outer sleeve 4, a ball screw mechanism 5 and a nut locking mechanism 6, in the figure, the nut 7 and the bolt 8 are used, the input torque is increased by the manual torque wrench through the speed reducing mechanism at the upper part, and the nut locking mechanism 6 is used for locking the bolt. The increased torque is transmitted to the ball screw mechanism in the middle through the outer sleeve, force in the tangential direction of the spiral ring channel is converted into force in the axial direction of the spiral ring channel through the screw mechanism, and therefore the nut is jacked and stretched, the bolt is stretched, the nut is screwed through the nut locking mechanism, and the stretching amount of the bolt is locked. The bolt tensioner is characterized in that a ball screw mechanism is adopted in the middle of the tensioner, torque acting on the ball screw mechanism can be converted into stretching force on a bolt with small rolling friction loss, compared with a hydraulic bolt tensioner, the bolt tensioner does not need any accessory device, can stretch the bolt in various occasions, is safe and reliable, and is trustworthy for people.

Description

[0001] Technical Field This invention relates to improvements in bolt tensioners for the tool industry.

[0002] Background technology is attached. Figure 1 A simplified diagram of a current hydraulic bolt tensioner is shown. In the diagram: 1-tension nut, 2-lever, 3-ring piston, 4-ring cylinder constitute the hydraulic bolt tensioner; 5-nut of the bolt to be tensioned; 6-upper flange; 7-lower flange; 8-bolt to be tensioned. The tensioner operates as follows: First, the lever is used to rotate the tension nut to tighten the bolt. Then, the high-pressure oil pump is started, and high-pressure oil enters the ring cylinder through the nozzle, lifting the ring piston, which in turn lifts the tension nut, stretching the bolt. At this time, the nut also disengages from the surface of the upper flange. When the oil pressure reaches the set value, the lever is immediately used to rotate the nut to lock the elastic elongation of the bolt. Thus, the upper and lower flanges are pressed together by the elastic force generated by the bolt elongation. After releasing the hydraulic pressure and loosening the tension nut, the bolt tensioner is removed. Bolts tightened by the tensioning method have accurate and reliable tightening force, thus fully utilizing the bolt's strength. Therefore, hydraulic bolt tensioners are widely used. However, they also have drawbacks. First, because the pressure-bearing area of ​​its annular cylinder is limited, the input oil pressure must be very high, approximately 100-150 MPa, which is ultra-high pressure. If there are manufacturing defects in the tensioner or operational errors, serious safety accidents can easily occur. Second, it requires connection to high-pressure oil pipes, high-pressure oil pumps, and other supporting devices to work, which is inconvenient to use and expensive. How can we find a bolt tensioner with good safety performance, convenient use, and a reasonable price?

[0003] The present invention aims to provide a mechanical bolt tensioner, which comprises a reduction mechanism at the top, a ball screw mechanism in the middle, and a nut locking mechanism at the bottom. A manual or electric torque wrench increases its input torque through the upper reduction mechanism, and then the increased torque is transmitted to the middle ball screw mechanism via an outer sleeve. The screw mechanism converts the tangential force along the helical ring into an axial force along the helical ring, thereby lifting the tension nut and stretching the bolt. When the torque wrench input torque reaches the set value, the lower nut locking mechanism immediately locks the bolt's elastic elongation with the nut. Thus, mechanical stretching of the bolt is achieved. It is evident that the bolt stretching force is derived from the input torque of the torque wrench. Therefore, each mechanical bolt tensioner is accompanied by a table relating input torque to stretching force. According to this table, the input torque of the torque wrench can be determined based on the required bolt stretching force, similar to how the hydraulic pressure of a hydraulic bolt tensioner is determined based on the required bolt stretching force.

[0004] The technical solution adopted by the present invention to solve the technical problem is: a mechanical bolt tensioner mainly composed of a deceleration mechanism located at the top, a ball screw mechanism located in the middle, and a nut locking mechanism located at the bottom. Its feature is that: the middle part of the tensioner adopts a ball screw mechanism, which can convert the torque acting on it into a tensioning force on the bolt with a small rolling friction loss.

[0005] The beneficial effects of the present invention are as follows: Compared with the hydraulic bolt tensioner, the mechanical bolt tensioner composed of the deceleration mechanism, the ball screw mechanism and the nut locking mechanism having the above-mentioned features does not require any auxiliary devices, can stretch bolts in various occasions, and is safe, reliable and reassuring to use.

[0006] Attached Figure Description Figure 1 This is a simplified structural diagram of a current hydraulic bolt tensioner.

[0007] Appendix Figure 2 This is a simplified structural diagram of the present invention.

[0008] Detailed implementation methods are attached. Figure 2 This is a preferred embodiment of the present invention, mainly composed of: 1-backstop mechanism, 2-manual torque wrench, 3-reduction mechanism, 4-tensioning nut, 5-outer flange, 6-ball bearing screw mechanism, 7-internal hex wrench, 8-nut locking mechanism, forming a mechanical bolt tensioner; 9-nut, 10-upper flange, 11-lower flange, 12-bolt. The tensioner operates as follows (see attached diagram). Figure 2 First, insert the bolt to be stretched into the lower and upper flanges and slightly tighten it with the nut. Then, put the tensioner onto the bolt and tighten it. Next, look up the input torque value from the reference table according to the given bolt tension force and adjust the manual torque wrench to this torque value. Then, insert the torque wrench into the reduction mechanism and turn it clockwise. At this time, the outer sleeve will drive the ball screw mechanism to rotate counterclockwise. As a result, a large axial thrust is generated on the screw ring of the mechanism, pushing the tension nut to stretch the bolt. As the torque of the manual torque wrench increases, stop turning when it makes a sound. Then, use an Allen wrench to turn the nut through the nut locking mechanism to lock the elastic elongation of the bolt. At this time, the upper and lower flanges will be pressed tightly by the elastic force of the bolt. Finally, pull out the manual torque wrench, open the backstop mechanism, and let the ball screw mechanism spring back to the initial position. Then, remove the tensioner. The entire operation is now complete.

Claims

1. A mechanical bolt tensioner, mainly composed of a reduction gear mechanism at the top, a ball screw mechanism in the middle, and a nut locking mechanism at the bottom, characterized in that: The tensioner employs a ball screw mechanism in the middle, which can convert the torque acting on it into a tensile force on the bolt with minimal rolling friction loss.

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