JPH0523976A - Bolt tensioner overstroke prevention method and prevention valve - Google Patents

Abstract

(57) [Summary] [Purpose] In a bolt tensioner, an attempt is made to prevent an overstroke by closing a fluid passage that operates a piston for pulling a bolt when the piston reaches a predetermined stroke. A nipple 15 that integrally operates with the piston 2 and a valve rod 14 that forms a pair with the nipple 15 and closes the fluid passage are arranged in the fluid passage that operates the piston 2 for pulling the bolt 16. When the piston 2 reaches a predetermined stroke, the fluid passage is closed by the contact between the conical portion 14a of the valve rod 14 and the seat portion 15a of the nipple 15.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bolt tensioner for tightening a lid for a pressure vessel, a piping flange, and a cable band for a bridge.

[0002]

2. Description of the Related Art A conventional bolt tensioner has prevented overstroke by the following method. 1. Warn the limit position of the stroke with a caution label, etc. 2. The piston stroke is limited by the lid. 3. When the stroke limit is reached, the relief valve is opened and fluid is released into the tank line. 4. The limit switch detects the piston stroke and stops the pump drive motor.

[0003]

However, there are the following methods for preventing the overstroke of the conventional bolt tensioner. With the method of, it is not possible to forcibly limit the stroke, so you must apply hydraulic pressure to the bolt tensioner while looking at the nameplate. 2. In this method, the piston pressurizes up to a maximum liquid pressure of 70 MPa, so the lid that serves as a stopper and the mounting bolts for the lid require excessive strength, which increases the weight of the bolt tensioner and, as a result, makes handling easier. Deteriorate. 3. In the method (1), a piping system that is directly connected to the tank is required in addition to the fluid supply piping system, and two hoses are connected to one bolt tensioner, which significantly impairs handling as a small machine. 4. In this method, an electric cable must be connected to the bolt tensioner. The present invention aims to solve such problems.

[0004]

SUMMARY OF THE INVENTION The present invention relates to a bolt tensioner for pulling a bolt 16 on an object to be fastened 18 by a hydraulic pressure and a nut 17 on the object to be fastened 18 for pulling the bolt 16. The fluid passage for operating the piston 2 is closed when the piston 2 reaches a predetermined stroke, and the fluid passage for operating the piston 2 for pulling the bolt 16 is integrated with the piston 2. By arranging the nipple 15 which is interlocked with the nipple 15 and the valve rod 14 which is paired with the nipple 15 and closes the fluid passage, the fluid passage is closed when the piston 2 reaches a predetermined stroke. Further, the above problem is solved by closing the fluid passage by contact between the conical portion 14a of the valve rod 14 and the seat portion 15a of the nipple 15.

[0005]

[Operation] Install a bolt tensioner on the object to be tightened 18,
The piston 2 of the bolt tensioner is fixed to the bolt 16 of the object to be fastened 18 by screwing. Then, when the fluid is supplied from the hydraulic pump (not shown) through the quick joint 12, the piston 2 rises together with the nipple 15 joint 7. When the piston 2 reaches the upper limit of the stroke, the conical portion 14a of the valve rod 14, which is pushed by the spring 13 and the lower end of which is always in contact with the bottom of the cylinder 1, is pressed against the seat portion 15a of the nipple 15. As a result, the fluid passage for the cylinder 1 is closed and the movement of the piston 2 is stopped. In order to return the piston 2 at the upper limit of the stroke for tightening the lever 6 and the nut socket 4 to the lower limit until the nut 17 contacts the object to be tightened 18 while the piston 2 is stopped, a hydraulic pump and a quick fitting The fluid between 12 is opened to atmospheric pressure by operating the valve on the hydraulic pump side.

[0006]

Embodiments of the present invention will now be described in detail with reference to the drawings. FIG. 1 is a sectional view of a bolt tensioner with an overstroke prevention valve according to the present invention, FIG. 2 is a side view of a valve rod used in the overstroke prevention valve according to the present invention, and FIG. 3 is a side view of the present invention. 3 is a cross-sectional view of a nipple used in the overstroke prevention valve of FIG.

In the bolt tensioner, a portion composed of the base 3 and the nut socket 4 is usually arranged at the portion of the bolt 16 and the nut 17 on the object to be fastened 18, and the cylinder 1
The piston 2 and the bolt 16 on the object 18 to be fastened can be screwed to each other, which is composed of the piston 2 and the cover 5. The fluid for operating the piston 2 is supplied from a hydraulic pump (not shown) through the joint 7 and the nipple 15 via the quick joint 12 set on the upper portion of the joint 7.

A nipple 15 is fixed to the upper surface of the piston 2 by screwing, and a hole 15b at the center of the nipple 15 serves as a fluid passage for operating the piston 2. Although the valve rod 14 can be inserted into the hole 15b at the center of the nipple 15, the fluid flows through the notch on the outer periphery of the valve rod 14. The valve rod 14 has an upper protrusion 14b, the spring 13 is arranged on the upper protrusion 14b, the other end of the spring 13 is brought into contact with the joint 7, and the joint 7 is fixed to the nipple 15 by screwing. . Therefore, the nipple 15 and the joint 7 are fixed to the piston 2 and move up and down together with the piston 2. Further, the valve rod 14 is pushed by the spring 13, and the lower end of the valve rod 14 is always in contact with the bottom of the cylinder 1.

The bolt stroke overstroke prevention valve according to the present invention is constructed as described above, and its operation will be described below. FIG. 4 is a diagram showing a state before fluid is supplied to the overstroke prevention valve of the present invention, and FIG. 5 is a state in which fluid is supplied to the overstroke prevention valve of the present invention and the piston starts to rise. FIG. 6 is a diagram showing a state in which the piston of the overstroke prevention valve of the present invention reaches the upper stroke limit.

First, the base 3 and the nut socket 4 of the bolt tensioner are arranged on the bolt 16 and the nut 17 on the object to be fastened 18, and the portion composed of the cylinder 1, the piston 2 and the cover 5 is separated. Piston 2 and tightened object 1
The bolt 16 on 8 is screwed. At this time, tighten the cylinder 1 until it comes into contact with the base 3. If the amount of screwing into the bolt 16 with respect to the piston 2 is small, or if the fluid is supplied to the bolt tensioner without the connection with the bolt 16, the piston 2 will have an overstroke.

Next, from the hydraulic pump to the quick grip 12
When the fluid is supplied through the piston 2, the piston 2
And the joint 7 and the seat portion 15a of the nipple 15 rises.
Is pressed against the conical portion 14a of the valve rod 14, and the cylinder 1
The fluid passage to is closed and the movement of the piston 2 stops. After the piston 2 stops moving, the nut 17
Is tightened by the nut socket 4 and the lever 6 until it comes into contact with the surface of the object to be tightened 18.

In order to return the piston 2 located at the upper limit of stroke to the lower limit, the fluid between the hydraulic pump and the quick joint 12 is opened to the atmospheric pressure by the valve operation on the hydraulic pump side. When the hydraulic pressure on the upstream side of the conical portion 14a of the valve rod 14 becomes close to the atmospheric pressure, the pressure inside the cylinder 2 is pushed up by the pressure generated by the residual pressure and the spring 9, and the fluid inside the cylinder 2 escapes to the hydraulic pump side. . At the same time, the conical portion 14a of the valve rod 14 separates from the seat surface 15a of the nipple 15. The piston 2 descends as the liquid escapes.
Once the piston 2 descends, the lower end of the valve rod 14 contacts the bottom of the cylinder 1. Since the piston 2 is pushed down by the spring 9, the fluid in the cylinder 1 is pushed back to the hydraulic pump side via the quick joint 12, and returns to the lower end of the piston 2.

[0013]

Since the stroke of the piston can be limited without impairing the operability of the bolt tensioner, it is possible to prevent the seal from protruding and the fluid from being ejected due to an erroneous operation. Further, when the conventional bolt tensioner is subjected to an overstroke during work, arrangement of a broken seal, disassembly, interruption of work due to assembly, and work of removing jetted fluid have a great influence on the work process. Further, when a fire is used near the bolt tightening work site, if a fluid such as hydraulic oil is ejected, there is even a risk of a disaster due to ignition, and these can be prevented in advance.

[Brief description of drawings]

FIG. 1 is a sectional view of a bolt tensioner with an overstroke prevention valve according to the present invention.

FIG. 2 is a side view of a valve rod used in the overstroke prevention valve of the present invention.

FIG. 3 is a sectional view of a nipple used in the overstroke prevention valve of the present invention.

FIG. 4 is a diagram showing a state before fluid is supplied to the overstroke prevention valve of the present invention.

FIG. 5 is a diagram showing a state in which fluid is supplied to the overstroke prevention valve of the present invention and the piston starts to rise.

FIG. 6 is a diagram showing a state in which the piston of the overstroke prevention valve of the present invention reaches the upper stroke limit.

[Explanation of symbols]

1 ... Cylinder 2 ... Piston 3 ... base 4 ... Nut socket 5 ... Cover 6 ... Lever 7 ... Joint 8 ... Centering plunger 9 ... Spring 10 ... Piston packing 11 ... Rod packing 12 ... Quick Tsugite 13 ... Spring 14 ... Valve rod 14a ... Conical part 14b ... Upper protrusion 15 ... Nipple 15a ... Seat section 15b ... Center hole 16 ... Bolt 17 ... Nut 18 ... Objects to be tightened

Claims (3)

[Claims] 1. A nut (1) on the object to be fastened (18) is pulled by hydraulically pulling a bolt (16) on the object to be fastened (18).
In the bolt tensioner for tightening 7), the fluid passage for actuating the piston (2) for pulling the bolt (16) is closed when the piston (2) reaches a predetermined stroke. How to prevent overstroke of bolt tensioner. 2. A nut (1) on the object to be fastened (18) is pulled by hydraulic pressure to pull a bolt (16) on the object to be fastened (18).
In a bolt tensioner for tightening 7), a nipple (15) that is integrally linked with the piston (2) and a nipple (15) that interlock with a passage of a fluid that operates a piston (2) for pulling the bolt (16). A bolt tensioner over which a valve rod (14) which is paired with 15) and which closes the fluid passage is arranged to close the fluid passage when the piston (2) reaches a predetermined stroke. Stroke prevention valve. 3. Closure of the fluid passage by means of a conical portion (14a) of the valve rod (14) and a seat portion (15) of the nipple (15).
The over-stroke prevention valve for a bolt tensioner according to claim 2, wherein the valve is brought into contact with a).