JP3634514B2 - Internal clamping device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention fixes the steel pipe and the steel pipe whose end portions are grooved from the inside of the pipe, and prior to the circumferential welding from the outer circumference to the steel pipe, aiming at the dimensional tolerance due to the manufacturing allowance of the steel pipe inner diameter and the flattening of the flat shape, The present invention relates to an internal clamp device for performing good circumferential welding.
[0002]
[Prior art]
Conventionally, when welding large-diameter steel pipes used for city gas supply etc., the steel pipes whose ends are grooved are fixed from the inside using an internal clamp device, and then the outer circumference of the steel pipe Circumferential welding is performed by an automatic welder from the part side.
Some of the inner diameters of steel pipes have dimensional tolerances or flat shapes due to manufacturing tolerances that are allowed when manufacturing steel pipes, and these need to be corrected prior to circumferential welding.
[0003]
An internal clamp device 40 disclosed in Japanese Patent Application No. 7-296607 by the applicant of the present application shown in FIG. 5 is one end of a link mechanism 31 connected to the end of the main cylinder 30 by the forward movement of the main cylinder 30. The plunger 35 is expanded in the outer circumferential direction of the steel pipes 20 and 20 by extending the plunger 35 connected to the other end of the link mechanism 31 by acting on the part, and the inner diameters of the steel pipes 20 and 20 are corrected. Is.
[0004]
At this time, the pipe expansion force (F) acting on the inner peripheral surfaces of the steel pipes 20 and 20 is the forward power (Q) generated when the main cylinder 30 moves forward and the link that is a boosting mechanism of the forward power (Q). Each element of the link angle (θ) formed by the mechanism 31 and the plunger 35 acts based on the following relational expression.
[0005]
F = Q / tan θ (relational expression of tube expansion force, forward power and link angle)
[0006]
[Problems to be solved by the invention]
FIG. 6 is an explanatory diagram of the relationship among the tube expansion force (F), the forward power (Q), and the link angle (θ) by the main cylinder 30, the link mechanism 31 and the plunger 35 of FIG. When the main cylinder 30 moves forward, the link angle (θ) extends in the circumferential direction of the main cylinder 30, and the link angle (θ1) at this time is smaller than that before the main cylinder 30 moves forward. It becomes an angle.
Therefore, when the link angle (θ1) is applied to the above relational expression, the pipe expansion force (F) of the plunger 35 changes when the forward power (Q) before and after the main cylinder 30 moves forward is constant. It is a large value when compared with before advance.
[0007]
Moreover, when the inner diameters of the steel pipes are corrected, a larger pipe expansion force (F) is required as the thickness of the steel pipes increases. Therefore, the pipe expansion force (F) is increased by an extremely slight change in the link angle (θ). Since F) changes greatly, there arises a problem that accurate tube expansion correction cannot be performed.
In the above-described conventional internal clamping device, the link angle (θ) is set to about 3 ° to 5 °, and the tube expansion force (F) can be increased by a very slight change in the link angle (θ). It changes a lot.
[0008]
The present invention has been made in order to eliminate such a problem, and the bottom shape of the plunger, to which a metal holder having a curved backing member mounted on the head is screwed and fixed, is a tapered inclined surface. The wedge rod cylinder, which is a wedge rod member having a wedge portion that engages with the inclined surface, always maintains a constant link angle between the plunger and the wedge rod cylinder without changing the angle. Since the power can be the tube expansion force to the plunger without changing the boost by the link mechanism, the dimensional tolerance due to the manufacturing tolerance of the steel pipe and the flat tube expansion correction can be performed accurately, and the wedge rod cylinder A guide hole having a key groove is formed in the shaft core in the advancing / retreating direction, and the guide shaft to which the guide shaft key is fixed is fitted into the guide hole. In order to allow the rotation restricting the straightness of the wedge rod cylinder, it is an object of the present invention to provide a internal clamping device.
[0009]
[Means for Solving the Problems]
As a first feature of the means for solving the above-described problems, the present invention is intended to fix the steel pipes whose end portions are grooved from the inside of the pipe and to expand the inner diameter of the steel pipes prior to circumferential welding. In an internal clamp device that performs correction by using a curved backing member that is mounted on the head of a plunger that is freely arranged to expand and contract radially in the plunger casing member, a plurality of wedge portions are formed on the outer peripheral surface. A wedge rod cylinder formed with an advance / retreat guide hole having a keyway in the axis of the advance / retreat direction and fixed to the internal clamp device inserted into the advance / retreat guide hole at a position facing the advance / retreat guide hole and a guide shaft provided with a guide shaft key, in contact with the wedge portion of each of the wedge rod cylinder by reciprocating the wedge rod cylinder, the flop Nja together to freely stretch radially, and to a structure in which straightness and rotation restricted by said guide shaft key and the key groove during reciprocating of the wedge rod cylinder is achieved.
[0010]
As a second feature, the plunger is a plunger that is screwed and fixed to a metal holder for mounting a curved backing member on the head, and is inserted perpendicularly to the axis of the plunger. A pin and a return spring engaged in a gap formed between the plunger pin and the plunger casing member,
The return spring is configured to apply an urging force when the wedge rod cylinder is retracted to the plunger that is extended as the wedge rod cylinder is advanced.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the internal clamp device of the present invention will be described below with reference to the accompanying drawings. The reference numerals used in the description of the conventional internal clamp device and the reference numerals used in the embodiments of the present invention will be described below. Among them, the same contents are denoted by the same reference numerals, and description of the contents is omitted.
[0013]
FIG. 1 is a partially broken side view showing an embodiment of an internal clamping device according to the present invention, FIG. 2 is an enlarged view of a portion A of FIG. 1, and (a) of this figure is an internal view. It is operation | movement explanatory drawing which shows before the action | operation of a clamp apparatus, (b) is an operation | movement explanatory drawing which shows the condition where the steel pipes mutual pipe expansion correction was carried out by the action | operation of an internal clamp apparatus.
FIG. 3 is an explanatory view for explaining the relationship between the tube expansion force, the forward power, and the link angle of the internal clamp device according to the present invention, and FIG. 4 is an arrow view from BB in FIG.
[0014]
1 and 2, reference numeral 1 denotes an internal clamp device. A wedge rod member of the internal clamp device 1 includes a wedge rod cylinder 2, a plunger 4, and a return spring 5. .
In the present embodiment, the wedge rod cylinder 2 is formed with nine inclined surfaces 2a on the outer peripheral portion thereof as shown in FIG. 4, and each inclined surface 2a is lubricated with a contact surface with the bottom of the plunger 4. The slide metal 3 is screwed and fixed with hexagon bolts 3a for strengthening protection.
The slide metal 3 on the inclined surface 2a may be mounted according to the situation such as the material strength of the wedge rod cylinder 2 and the plunger 4.
[0015]
The plunger 4 is radially arranged to freely expand and contract within a plunger casing member 10 provided in the internal clamp device 1.
Since the bottom portion of the plunger 4 is shaped to abut against the inclined surfaces of the wedge rod cylinder 2, the plunger 4 moves as the wedge rod cylinder 2 advances as shown in FIG. Stretch radially.
[0016]
A plunger pin 4a is mounted at a predetermined position of the plunger 4 so as to be orthogonal to the axis of the plunger 4, and an elastic member is provided in a gap generated between the plunger pin 4a and the casing member 10 of the plunger 4. The return spring 5 is engaged.
The return spring 5 applies a biasing force when the wedge rod cylinder 2 is retracted to the plunger 4 that is extended by the advancement of the wedge rod cylinder 2.
Further, bushes 7 a and 7 b are attached to the contact portion between the outer peripheral portion of the plunger 4 and the plunger casing member 10, so that the plunger 4 can be smoothly expanded and contracted by 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.
[0017]
Reference numeral 6 denotes a guide shaft provided with a guide shaft key 6a. The guide shaft 6 is screwed and fixed to the front end portion of the internal clamp device 1, and is formed at the axial center of the wedge rod cylinder 2. The wedge rod cylinder 2 is inserted into the advanced / retracted guide hole 12 and is disposed for the purpose of straightness when the wedge rod cylinder 2 is advanced and retracted and for preventing the wedge rod cylinder 2 from being twisted.
[0018]
Although the drive source of the wedge rod cylinder 2 is a hydraulic pump in the present embodiment, depending on the situation such as the object with a thin steel pipe thickness, it may be a pneumatic drive source, 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 according to the situation.
[0019]
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 placed on the inner side of the place where the circumferential welding of the steel pipe 20 whose edge is grooved is performed. Is moved forward to the center of the backing member 25 mounted on the backing holder 26.
And the cylinder of the clamp part 15 is extended and the internal clamp apparatus 1 is fixed to the inner side of the steel pipe 20.
Thereafter, the hydraulic cylinder 9 driven by the hydraulic pump 16 advances the wedge rod cylinder 2.
The plunger 4 in contact with the slide metal 3 screwed on the inclined surface 2 a of the wedge rod cylinder 2 extends as the wedge rod cylinder 2 advances.
The link angle (θ) formed by the wedge rod cylinder 2 and the plunger 4 at this time 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 and 20 while maintaining the angle, and a load is applied to the wedge rod cylinder 2 until the predetermined inner circumference is obtained, and the pipe is expanded. After the circumference, circumferential welding of the steel pipes 20 and 20 is performed.
[0020]
When the circumferential welding is completed, the wedge rod cylinder 2 is retracted and the plunger 4 is retracted. At this time, a back wave beat (not shown) generated in the inner circumferential portion of the steel pipes 20 and 20 by the circumferential welding is described above. In some cases, the return spring 5 engaged with the gap between the casing member 10 and the plunger pin 4a of the plunger 4 is extended. Thus, the plunger 4 is smoothly retracted.
[0021]
【The invention's effect】
The internal clamping device of the present invention described above has the following effects.
[0022]
A wedge rod member provided with a wedge portion engaged with the inclined surface is formed as a tapered inclined surface with a bottom shape of a plunger screwed and fixed to a metal holder having a curved backing member mounted on the head. In order to make the advance and retreat freely, the link angle between the plunger and the wedge rod cylinder is always constant without changing the angle. Therefore, the forward force by the wedge rod cylinder is not lost by the link mechanism, and the expansion force to the plunger is reduced. Therefore, it is possible to accurately perform expansion correction of the dimensional tolerance due to the manufacturing tolerance of the steel pipe and the dimensional difference of the steel pipe having a flat shape due to an external load.
[0023]
In addition, a guide hole having a key groove is formed in the axial center of the wedge rod cylinder, and the guide shaft with the guide shaft key fixed is inserted into the guide hole. There is an effect that regulation is achieved.
[Brief description of the drawings]
FIG. 1 is a partially broken side view showing an embodiment of an internal clamp device according to the present invention.
FIG. 2 is an enlarged explanatory view of a part A in FIG. 1, in which (a) of FIG. 1 is an operation explanatory view showing the operation of the internal clamp device, and (b) is an operation of the internal clamp device. It is operation | movement explanatory drawing which shows the condition where the steel pipe mutual pipe expansion correction was carried out.
FIG. 3 is an explanatory diagram for explaining a relationship among tube expansion force, forward power, and link angle of the internal clamp device according to the present invention.
4 is a view taken along the line BB in FIG. 3;
FIG. 5 is a cutaway side view of a conventional internal clamp device.
FIG. 6 is an explanatory view for explaining the relationship between tube expansion force, forward power and link angle in a conventional internal clamp device.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Internal clamp apparatus 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 Contact holder 30 Main cylinder 31 Link mechanism 35 Plunger 40 Internal clamp device (conventional)
F Expanding force Q Forward power θ Link angle

Claims (2)

Prior to circumferential welding, the steel pipes whose ends are grooved are fixed from the inside of the pipe, and the expansion of the inner diameters of the steel pipes is corrected in a radial manner within the plunger casing member. In the internal clamping device that is performed by a curved backing member attached to the head,
A wedge rod cylinder in which a plurality of wedge portions are formed on the outer peripheral surface, and an advance / retreat guide hole having a key groove is formed in the axial center of the advance / retreat direction ;
A guide shaft provided with a guide shaft key fixed to the internal clamp device to be inserted into the advance / retreat guide hole at a position facing the advance / retreat guide hole;
When the wedge rod cylinder abuts on each wedge portion and the wedge rod cylinder advances and retreats, the plunger can expand and contract radially, and when the wedge rod cylinder advances and retreats by the key groove and the guide shaft key. It is characterized by straightness and rotation regulation in
Internal clamping device. The plunger includes a plunger holder for mounting a curved backing member on its head by screwing, a plunger pin inserted perpendicularly to the axis of the plunger, and the plunger pin and plunger casing. And a return spring engaged with a gap formed between the member and the return spring for applying a biasing force when the wedge rod cylinder is retracted to the plunger extended with the advancement of the wedge rod cylinder. It is characterized by
The internal clamping device according to claim 1.

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