JPH1076394A - Internal clamp device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the dimensional tolerance of a steel tube, to expand and straighten its flat shape and to enable an excellent circumferential welding by forming the bottom part of the plunger fixed a strap holder into an inclined surface and engaging a wedge rod cylinder with the inclined surface. SOLUTION: An internal clamp device 1 is butted to the rear part of the predetermined place of the circumferential welding in the steel tube 20 and advanced to the center of a backing 25. The cylinder of a clamp part 15 is extended and internal clamp device 1 is fixed inside the steel tube 20. A hydraulic pump 16 is driven to advance the wedge rod cylinder 2, whereby a plunger 4, abutted to a slide metal 3 screwed the inclined surface of the wedge rod cylinder 2, is extended. At this time, the backing 25 is pressed to the inner peripheral surface of the steel tube 20 in accordance with the link angle formed with the wedge rod cylinder 2 and plunger 4. In this way, a load is applied to the wedge rod cylinder 2 until a prescribed inner circumference is obtained, whereby the tube is expanded. The inner circumferential welding for the steel tube 20 is executed after a prescribed inner circumference of the steel tube 20 is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a steel pipe having a grooved end and a steel pipe fixed from the inside of the pipe. The present invention relates to an internal clamp device for performing pipe expansion correction of a shape and performing favorable circumferential welding.

[0002]

2. Description of the Related Art Conventionally, when welding large-diameter steel pipes used for supplying city gas or the like, the steel pipes whose edges are grooved are fixed from the inside using an internal clamp device. After that, circumferential welding is performed by an automatic welding machine from the outer peripheral side of the steel pipe. Some steel pipes have dimensional tolerances or flat shapes due to manufacturing tolerances allowed in the manufacture of steel pipes, and these need to be corrected prior to circumferential welding.

FIG. 5 shows a Japanese Patent Application No. 7-2 by the present applicant.
The internal clamp device 40 disclosed in Japanese Patent No. 96607 acts on one end of a link mechanism 31 connected to an end of the main cylinder 30 by the forward movement of the main cylinder 30, and the other end of the link mechanism 31 By extending the plunger 35 connected to the portion, the plunger 35 is expanded in the outer circumferential direction of the steel pipes 20, 20, and the steel pipe 20,
20 for correcting the inner diameter of each other.

At this time, the pipe expanding force (F) acting on the inner peripheral surfaces of the steel pipes 20, 20 is generated by a forward power (Q) generated when the main cylinder 30 moves forward and a booster mechanism of the forward power (Q). Each element of the link angle (θ) formed by the link mechanism 31 and the plunger 35 acts based on the following relational expression.

F = Q / tan θ (relational expression between pipe expansion force, forward power, and link angle)

[0006]

FIG. 6 is an explanatory diagram showing the relationship between the pipe expanding force (F), the forward power (Q), and the link angle (θ) by the main cylinder 30, the link mechanism 31, and the plunger 35 in FIG. However, in such a relationship, the plunger 35 extends in the circumferential direction of the main cylinder 30 when the main cylinder 30 advances, and the link angle (θ1) at this time becomes 3
The angle is smaller than before the zero advance. Therefore, when the link angle (θ1) is applied to the above relational expression, and when the forward power (Q) before and after the forward movement of the main cylinder 30 is constant, the pipe expansion force (F) of the plunger 35 changes,
The value is large when compared with before the advance.

Furthermore, when correcting the inner diameter of the steel pipes,
Since the pipe expansion force (F) is required to increase as the thickness of the steel pipe increases, the pipe expansion force (F) greatly changes due to a very small change in the link angle (θ). The problem that correction cannot be performed occurs.
In the above-mentioned conventional internal clamping device, the link angle (θ) is set to a value of about 3 to 5 degrees, and even if the link angle (θ) changes very slightly, the pipe expanding force (F) can be reduced. It changes greatly.

SUMMARY OF THE INVENTION The present invention has been made to solve such a problem. The bottom of a plunger in which a backing holder having a curved backing member mounted on a head is screwed and fixed has a tapered inclined surface. In addition, the wedge rod cylinder, which is a wedge rod member having a wedge portion engaged with the inclined surface, always keeps the link angle between the plunger and the wedge rod cylinder constant without changing the angle. Since the forward power of the cylinder can be used as the expanding force of the plunger without changing the boosting force of the link mechanism, dimensional tolerances due to manufacturing tolerances of steel pipes and straightening of flattened pipes can be accurately corrected. A guide hole having a key groove is formed in the axis of the rod cylinder in the reciprocating direction. To be fitted through, to enable rotation restricting the straightness of the wedge rod cylinder, it is an object of the present invention to provide a internal clamping device.

[0009]

According to the present invention, as a first feature of the means for solving the above-mentioned problems, steel pipes whose ends are beveled are fixed to each other from inside the pipe, and prior to circumferential welding. A wedge rod cylinder having a plurality of wedge portions formed on an outer peripheral surface thereof, wherein said wedge rod cylinder has a curved backing member mounted on a head of a plunger. A configuration is such that the plunger radially expands and contracts radially by advancing and retreating of the wedge rod cylinder by contacting each wedge portion of the cylinder.

As a second feature, the plunger is
A screw holder for attaching a curved backing member to the head is screwed and fixed, and a plunger pin inserted perpendicular to the axis of the plunger is inserted between the plunger pin and the plunger casing member. And a return spring engaged with the plunger extended with the advance of the wedge rod cylinder to apply a biasing force when the wedge rod cylinder is retracted. is there.

As a third feature, the wedge rod cylinder is provided with an advance / retreat guide hole having a key groove in an axis of the wedge rod cylinder in the advance / retreat direction. A wedge rod cylinder which is screwed and fixed to the front end, is fitted through a guide shaft to which a guide shaft key is fixed, and allows the wedge rod cylinder to freely move forward and backward, so as to achieve a straight movement and a rotation restriction.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the internal clamp device of the present invention will be described below with reference to the accompanying drawings. The same reference numerals are used for the same contents among the reference numerals used in the embodiments, and the description of the contents is omitted.

FIG. 1 is a partially cutaway side view showing an embodiment of an internal clamp device according to the present invention, and FIG. 2 is an enlarged explanatory view of a portion A in FIG. FIG. 4 is an operation explanatory view showing a state before the operation of the internal clamp device, and FIG. 4B is an operation explanatory view showing a state in which the steel pipes are expanded and corrected by the operation of the internal clamp device. FIG. 3 is an explanatory diagram for explaining the relationship between the pipe expanding force, the forward power, and the link angle of the internal clamp device according to the present invention, and FIG. 4 is a view taken along the line BB in FIG.

1 and 2, reference numeral 1 denotes an internal clamp device, and a wedge rod member of the internal clamp device 1 includes a wedge rod cylinder 2
, Plunger 4 and return spring 5. In this embodiment, the wedge rod cylinder 2 has nine inclined surfaces 2a at its outer peripheral portion as shown in FIG. 4, and each inclined surface 2a has a lubricating surface for contact with the bottom of the plunger 4. The slide metal 3 is screwed and fixed by a hexagon bolt 3a for strengthening protection. The slide metal 3 on the inclined surface 2a is a wedge rod cylinder 2
What is necessary is just to mount according to conditions, such as the material strength of the plunger 4 and plunger 4.

The plunger 4 is radially and freely expandable and contractable in a plunger case member 10 provided in the internal clamp device 1. Since the bottom of the plunger 4 is formed in such a shape as to come into contact with each inclined surface of the wedge rod cylinder 2, the plunger 4 moves as the wedge rod cylinder 2 advances as shown in FIG. Extend radially.

A plunger pin 4a is mounted at a predetermined position of the plunger 4 at right angles to the axis of the plunger 4, and a gap formed between the plunger pin 4a and the casing member 10 of the plunger 4 is provided. A return spring 5 as an elastic member is engaged. The return spring 5 applies an urging force to the plunger 4 extended by the advance of the wedge rod cylinder 2 when the wedge rod cylinder 2 is retracted. Further, bushes 7a and 7b are mounted on the contact portion between the outer peripheral portion of the plunger 4 and the plunger casing member 10, so that the plunger 4 can smoothly expand and contract with the plunger casing member 10. The bushes 7a and 7b may be mounted according to the material strength of the plunger 4 and the plunger casing member 10, and the like.

Reference numeral 6 denotes a guide shaft provided with a guide shaft key 6a.
Is screwed and fixed to the front end of the internal clamp device 1 and is inserted into an advance / retreat guide hole 12 formed in the axis of the wedge rod cylinder 2 in the advance / retreat direction, so that the linearity of the wedge rod cylinder 2 when the wedge rod cylinder 2 advances / retreats. The wedge rod cylinder 2 is disposed for the purpose of preventing the wedge rod cylinder 2 from being twisted.

The drive source of the wedge rod cylinder 2 is a hydraulic pump in the present embodiment, but may be an pneumatic drive source depending on the condition of a thin steel pipe to be processed. Further, the inclined surface 2a formed on the outer peripheral portion of the wedge rod cylinder 2 is a nine-sided body, but may be another polyhedron depending on the situation.

The operation of the internal clamp device according to the present invention having such a configuration will be described. First, the internal clamp device 1 is mounted on the inner side of the portion where the circumferential end of the steel pipe 20 whose end is to be welded is to be welded. Then, it is advanced to the center of the backing member 25 attached to the backing holder 26 at the lower part of the welding location. Then, the cylinder of the clamp portion 15 is extended to fix the internal clamp device 1 inside the steel pipe 20. Thereafter, the hydraulic cylinder 9 driven by the hydraulic pump 16 advances the wedge rod cylinder 2. Slide metal 3 screwed to the inclined surface 2a of the wedge rod cylinder 2
The plunger 4 in contact with the cylinder extends as the wedge rod cylinder 2 advances. At this time, the link angle (θ) formed by the wedge rod cylinder 2 and the plunger 4 is the same as the link angle (θ) formed by the link mechanism 31 and the plunger 35 shown in FIG. , The backing member 25 is pressed against the inner peripheral surfaces of the steel pipes 20, 20, and a load is applied to the wedge rod cylinder 2 until the inner circumference of the steel pipes 20, 20 is expanded to perform pipe expansion. After the circumference, circumferential welding of the steel pipes 20, 20 is performed.

When the circumferential welding is completed, the wedge rod cylinder 2 is retracted and the plunger 4 is retracted. At this time, a Uranami beat (not shown) generated on the inner peripheral portions of the steel pipes 20, 20 by the circumferential welding. May be welded to the surface of the backing member 25 to hinder the retraction of the plunger. In such a case, the return spring 5 engaged with the gap between the casing member 10 and the plunger pin 4a of the plunger 4 may be used. Extend to make the retraction of the plunger 4 smooth.

[0021]

According to the internal clamp device of the present invention described above, the following effects can be obtained.

A bottom portion of a plunger in which a backing holder having a curved backing member mounted on a head is screwed and fixed has a tapered inclined surface, and a wedge provided with a wedge portion engaged with the inclined surface. In order to allow the rod member to move freely,
Since the link angle between the plunger and the wedge rod cylinder is always constant without changing the angle, the forward power by the wedge rod cylinder can be used as the expanding force to the plunger without being lost by the link mechanism.
There is an effect that the dimensional tolerance of the steel pipe having a flat shape due to an external load and the dimensional tolerance due to the manufacturing tolerance of the steel pipe can be accurately expanded and corrected.

Further, a guide hole having a key groove is formed in the axis of the wedge rod cylinder in the reciprocating direction, and the guide shaft to which the guide shaft key is fixed is inserted through the guide hole. There is an effect that straightness and rotation are regulated.

[Brief description of the drawings]

FIG. 1 is a partially cutaway side view showing an embodiment of an internal clamp device according to the present invention.

FIG. 2 is an enlarged explanatory view of a portion A in FIG. 1; FIG. 2 (a) is an operation explanatory view showing a state before an internal clamp device is operated, and FIG. It is operation | movement explanatory drawing which shows the state in which the steel pipe mutually expanded and corrected.

FIG. 3 is an explanatory diagram illustrating a relationship among a pipe expanding force, a forward power, and a link angle of the internal clamp device according to the present invention.

FIG. 4 is a view taken in the direction of arrows B-B in FIG. 3;

FIG. 5 is a cutaway side view of a conventional internal clamp device.

FIG. 6 is an explanatory diagram for explaining a relationship between a pipe expanding force, a forward power, and a link angle in a conventional internal clamp device.

[Explanation of symbols]

 Reference Signs List 1 internal clamp device 2 wedge rod cylinder 2a inclined surface 3 slide metal 3a hexagon bolt 4 plunger 4a plunger pin 5 return spring 6 guide shaft 6a guide shaft key 7a bush 7b bush 9 hydraulic cylinder 10 plunger casing member 12 advance / retreat guide hole 15 clamp Part 16 Hydraulic pump 20 Steel pipe 25 Backing member 26 Backing holder 30 Main cylinder 31 Link mechanism 35 Plunger 40 Internal clamping device (conventional) F Expanding force Q Forward power θ Link angle

Claims (3)

[Claims] 1. A curved backing member in which steel pipes whose ends are beveled are fixed from the inside of the pipes and prior to girth welding, expansion correction of the inner diameters of the steel pipes is mounted on the head of a plunger. A wedge rod cylinder having a plurality of wedge portions formed on an outer peripheral surface thereof;
An internal clamp device wherein the plunger radially expands and contracts radially by advancing and retreating of the wedge rod cylinder by abutting each wedge portion of the wedge rod cylinder. 2. The plunger has a plunger pin which is screwed and fixed to a head thereof for mounting a curved backing member, and which is inserted perpendicular to the axis of the plunger. A return spring engaged with a gap formed between the plunger pin and the plunger casing member. The return spring attaches to the plunger extended with the advance of the wedge rod cylinder when the wedge rod cylinder is retracted. 2. The internal clamp device according to claim 1, wherein the internal clamp device has a structure for applying a force. 3. The wedge rod cylinder has an advance / retreat guide hole provided with a key groove at an axis of the advance / retreat direction of the wedge rod cylinder, and is screwed and fixed at a position facing the advance / retreat guide hole. 2. The internal clamp device according to claim 1, wherein the wedge rod cylinder is fitted into a guide shaft to which a guide shaft key is fixed, and is capable of freely moving forward and backward.