JPS63135607A - Nut for bolt tensioner - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a technique for tightening bolts and nuts on a flange portion using a bolt tensioner, and particularly relates to a technique for tightening bolts and nuts on a flange portion.

The present invention relates to a structure of a nut suitable for tightening a turbine high pressure casing flange.

[Conventional technology]

Conventional nuts have an integral structure as a whole, and even if they have a split structure, for example, as described in JP-A-50-45158, each nut has a female thread and is fastened to a bolt. ing. Therefore, when tightening a nut with this structure with a bolt tensioner, the legs of the bolt tensioner's reaction force receiver are set on the flange surface on the outer periphery of the nut, and after the bolt is pulled up, the nut is tightened, and the pressure is removed and tightened. had been completed.

[Problem that the invention seeks to solve]

However, with this technology, the reaction force necessary to generate the axial force of the bolt is transmitted to the flange surface of the outer periphery of the nut by the cylindrical component of the bolt tensioner. When the distance between the bolts is short and the area of the flat part of the flange is extremely small, as in the case of the above example, there is no place to receive the reaction force.

Furthermore, due to strength issues, it is not possible to reduce the wall thickness of the nut and set the location where the reaction force of the bolt tensioner is received, making it impossible to use the bolt tensioner.

An object of the present invention is to provide a nut that allows the use of a bolt tensioner with any flange-shaped bolt joint.

[Means for solving problems]

The above purpose is to create a truncated cone-shaped part whose generating line is narrower from the upper end face to the lower end face of the nut in the cross section in the normal setting state, including all the threaded parts, and the remaining outer surface. Using a nut with a structure divided into two parts, the upper end surface of the outer component part of the nut transmits the reaction force when the bolt tensioner is activated to the flange surface, and when removing the bolt tensioner after setting is completed, the reaction force is transmitted to the flange surface. This is achieved by transmitting the axial force of the bolt from the inner component of the nut to the outer component via the slope.

[Effect]

The above nut has the function of transmitting the force from the upper part of the nut to the flange surface of each component, and the reaction force when the bolt tensioner is activated is received by the upper end surface of the outer component, increasing the area of action. transmitted to the flange surface. On the other hand, the inner component including the threaded part, which is pulled up at the same time as the bolt tensioner operates, is screwed back to its original position while the bolt tensioner is operating, but the axial force generated after the hydraulic pressure is removed is applied along the generatrix i of the truncated cone. It is transmitted through the contact surface to the outer component and through the lower end surface of the inner component to the flange surface. In this way, it is possible to perform tightening using bolt tension using only the upper end surface of the nut without using the flange on the outer periphery of the nut as a reaction force receiver.

The inner component and the outer component are connected by a removable pin, and have a function to prevent slipping when installed.

〔Example〕

An embodiment of the present invention will be described below. FIG. 1 is a structural diagram of a nut according to the present invention. The nut consists of an inner component 1 including a threaded portion and an outer component 2 including an outer surface. The inner component part 1 and the outer component part 2, which have a hollow truncated cone shape with a large top, are in complete contact with each other on the generatrix of the cone, and in this state are connected by the pin 3, so that both are prevented from idling.
It has the functions of a normal Natsuto. Figure 2 shows nuts and bolts 7 of this structure for tightening the flange 8.
are temporarily tightened, and a bolt tensioner consisting of a base 4, a piston 5, and a puller 6 is attached. A base 4 is set on the outer component 2 of the nut, on which there is a hydraulically actuated piston 5 and also a puller 6 which is in contact with the piston 5 and connected by a screw with a bolt 7. At this point, the preparation for tightening is completed by removing the pin 3, and after the preparation is completed, hydraulic pressure is applied to the piston 5 to raise the puller 6. Due to the accompanying axial deformation of the bolt 7, the nut inner component 1 also rises by the amount of elongation of the bolt, resulting in a state as shown in FIG. 3. In this state, the reaction force of the axial force generated in the bolt is transmitted from the base 4 to the flange 8 through the nut outer component 2, but the nut outer component 2 has a lower area that is larger than the area of the upper end surface. is large, so the ground pressure against the flange 8 is lower than the base 4.
As shown in Fig. 4, after completing the above operations, remove the hydraulic pressure. , the state shown in FIG. 5 is reached. That is, the puller 6, the base 4, and the nut outer component 2 are moved by hydraulic pressure.
By removing the hydraulic pressure, the force generated between the bolt 7 and the flange 8 via the nut components 1 and 2 is converted into a force that acts between the bolt 7 and the flange 8 via the nut components 1 and 2. This is the tightening force for the flange. In the above process, the force applied to the nut is analyzed as shown in Fig. 6. In the state shown in Fig. 2, no interaction has occurred, and in Fig. 3, in the nut outer component 2, the force generated by the hydraulic pressure is Force P1 is on surface A
It depends on x.

This force is transmitted to the surface A8 as P8, but A1(A
3, the ground pressure applied to the flange is smaller in the artist 8, and the structure is such that local stress generation in the flange is alleviated. The operating state of the force in FIG. 4 is the same as in FIG. 3, only the nut inner component 1 has moved. FIG. 5 shows the state in which the hydraulic pressure was removed after the state shown in FIG. 4. At this stage of transition, force P1 gradually becomes smaller, and force P2. gradually becomes larger. FIG. 5 shows a state in which Pl is completely replaced with P2. The tensile force P2 of the bolt 7 is transmitted to the nut component 1, which is transmitted via the plane A4 and the nut component 2 to the plane Aδ. At this time, a force P perpendicular to the slope acts from the inner nut component 1 to the outer component 2, and this is composed of a force P sinθ that pushes the outer component 2 outward, and a force P eo that tightens the bolt.
It is decomposed into sθ. That is, when the tightening is completed, the force P2 is transmitted to the flange surface as P4 from the surface A4 and as P cos θ from the surface Aδ.

〔Effect of the invention〕

According to the present invention, it can be applied to bolt joints with any flange shape, and even in the case of strength problems, the same size nut as the conventional one can be used without making the nut thinner, making it easier to replace the nut. This makes it possible to apply bolt tensioners under the same performance conditions.

[Brief explanation of the drawing]

Fig. 1 is a sectional view of a nut according to an embodiment of the present invention, Figs. 2 to 5 are illustrations of an embodiment of tightening work using a pole 1 tensioner using a nut according to the present invention, and Fig. 6 is a cross-sectional view of a nut according to an embodiment of the present invention. FIG. 3 is an enlarged view of a cross section of a nut for explaining the force acting on the nut according to the invention. ], ... Nut inner constituent part, 2... Nut outer constituent part.

Claims (1)

[Scope of Claims] 1. A bolt tensioner that generates axial force by tightening the bolt and nut of the flange joint portion with the bolt being deformed in the axial direction by hydraulic pressure and removing the hydraulic pressure, comprising: It is characterized by having a structure in which the axial force generated by the tensioner is received by its outer upper end surface, and the interior is divided into a truncated conical part including the threaded part and the other part, and these parts are connected with a pin. Nut for bolt tensioner.