Connection mechanism between steel pipe and fitting

Abstract

To provide a connection mechanism which is less likely to cause a nut fastening a steel pipe to a joint for connection to loosen, and a connection method.SOLUTION: A connection mechanism grips a steel pipe 2 having a crest type projection 21 on an end 2a side with a joint 3 and a nut 4 for connection. The joint is provided with a plurality of engagement blades in a circumferential direction at an end of an outer periphery of a connection cylinder part. The nut has an annular outer cylinder part 41 externally fitted to an outer periphery of the engagement blade and a steel pipe pressing part 43. In an inner periphery of the annular external cylinder part, a fully fastening ring 6 and a temporarily fastening ring are mutually unseparably / non-approachably and freely rotatably provided in a circumferential direction, the end 2a of the steel pipe is inserted in the connection cylinder part, the end side inclined surface 21a of the crest type projection 21 is pressed with a packing 5, the inner inclined surface 21b is pressed with the steel pipe pressing part 43, a temporarily fastening blade of the temporarily fastening ring is engaged unrotatably in the circumferential direction, and a fully fastening blade is positioned opposite the steel pipe pressing part of the engagement blade to block a force in a slipoff direction, so that the joint and the nut are connected and fixed.SELECTED DRAWING: Figure 1

Claims

1. A connection mechanism between a steel pipe and a fitting, in which a steel pipe having a mountain-shaped protrusion on the end side is connected by sandwiching it between a fitting and a nut, The joint has a medium expansion section on the inner periphery side of the connecting tubular section at the end of the connecting tubular section having a fluid passage therein, through which the outer periphery of the end side of the steel pipe is inserted, and further has a packing storage section which is a large expansion section with an even larger diameter than the medium expansion section and opens to the end, and has a flange section extending outward on the outer periphery near the boundary between the connecting tubular section and the connecting tubular section, and is provided with a plurality of engaging blades at a predetermined interval in the circumferential direction at the tip of the outer periphery of the connecting tubular section, and a plurality of stoppers are provided at a predetermined interval in the axial direction from the engaging blades and located between the width direction of the intervals of the engaging blades spaced in the circumferential direction of the engaging blades, The nut has an annular outer tubular portion that fits onto the outer periphery of the engaging blade of the connecting tubular portion, and a steel pipe pressing portion that forms a pipe insertion hole in the center at one end side of the annular outer tubular portion, through which the steel pipe is inserted, and is equipped with an inclined pressing surface that presses the inner inclined surface of the mountain-shaped protrusion of the steel pipe, and on the inner periphery of the annular outer tubular portion, a final fastening ring and a temporary fastening ring are provided, in order from the side closest to the inclined pressing surface, at a predetermined interval in the axial direction so as to be inseparable from each other and to be freely rotatable in the circumferential direction, the temporary fastening ring is arranged rotatably together with the annular outer tubular portion, while the final fastening ring is capable of rotating independently by a predetermined angle, and on the inner periphery of the final fastening ring and the temporary fastening ring, final fastening blades and temporary fastening blades having a predetermined circumferential length and a predetermined protruding height toward the center are provided at an interval equivalent to or greater than the circumferential length of the engaging blade, The end side of the steel pipe inserted into the pipe insertion hole of the nut is inserted into the connection tube portion, and the packing stored in the packing storage portion is used to press the end side inclined surface of the mountain-shaped protrusion, and the inclined pressing surface is used to press the inner side inclined surface of the mountain-shaped protrusion, so that the temporary fastening blade of the temporary fastening ring abuts against the stop block and is locked so as not to move in the axial direction, and the main fastening blade is sandwiched between the engagement blades and cannot rotate, and the temporary fastening blade is moved by the rotation of the nut. A connection mechanism for a steel pipe and a fitting, characterized in that a temporary tightening is performed in which the gasket is positioned on the side of the engaging blade to prevent movement in the removal direction, and then the gap between the nut and the fitting is further tightened to reduce the packing, and the final tightening ring is rotated, and final tightening is performed to position the final tightening blade on the side of the engaging blade in a state where it cannot move, thereby connecting and fixing the fitting and the nut in a mutually non-rotatable state while preventing the force in the removal direction from the annular outer tubular portion to the connecting tubular portion.

2. The connection mechanism for a steel pipe and a fitting as described in claim 1, characterized in that the structure in which the final tightening ring and the temporary tightening ring are arranged on the inner circumference of the annular outer tube portion at a predetermined axial distance so that they cannot move toward each other and can rotate freely in the circumferential direction is a structure in which the outer circumferences of the final tightening ring groove provided on the inner circumference of the annular outer tube portion and the temporary tightening ring groove provided at a predetermined distance from the final tightening ring groove in the axial direction are respectively fitted rotatably into each other.

3. The connection mechanism for a steel pipe and a joint as described in claim 1 or 2, characterized in that the final tightening ring and the temporary tightening ring are elastic rings having hook portions or locking heads at both ends of a cutout portion of the ring.

4. 3. A connection mechanism for a steel pipe and a joint according to claim 2, wherein the main tightening ring is made of a metal material and the temporary tightening ring is made of a synthetic resin material.

5. 2. A connection mechanism for a steel pipe and a joint according to claim 1, further comprising a rotation stop bar provided at a predetermined interval in the axial direction between said stop block and said engagement blade interval.

6. 4. A connection mechanism for a steel pipe and a joint according to claim 3, characterized in that the locking heads provided at both ends of the notch of the temporary tightening ring have bulges in the direction of the final tightening ring.

7. 4. A connection mechanism for a steel pipe and a joint according to claim 3, characterized in that a locking projection is provided on the outer periphery in the vicinity of the hook portion provided at both ends of the notch of the tightening ring.

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