JPH03234328A - Pipe expanding device for thin steel pipe - Google Patents

Abstract

PURPOSE:To easily form the annular chevron projection in a thin steel pipe so as to be stable in a long period by fixing a piston rod and a pipe expansion head to a piston bounced elastically with a compression coil spring, and forming an annular peripheral groove between the pipe expansion head and a bush. CONSTITUTION:On a hydraulic cylinder in which a cover 3a and a body 3b are formed integrally, a piston 4 which is bounced elastically by a compression coil spring 5, and also, for which a piston rod 4a is fixed is provided. To the outer end 4b of this piston rod 4a, a pipe expansion rod 8 is connected through a connecting tool 9. Subsequently, a bush 10 is inserted and screwed into a pipe expansion head 7 connected to the tip of the above-mentioned hydraulic cylinder 3, and by tapered faces 7a, 10c of both of them, an annular peripheral groove 16 is formed. Next, a thin steel pipe 2 is inserted between the bush 10 and the pipe expansion head 7, and a large diameter part 8b of the pipe expansion rod 8, and the piston 4 is operated against the elasticity of the spring 5 by hydraulic pressure. In such a manner, pipe expansion rubber 12 is pressurized by a spacer 11 provided on a small diameter part 8a of the pipe expansion rod 8 and the large diameter part 8b, a pipe end part of the thin steel pipe 2 is bulged along the annular peripheral groove 16, and an annular chevron projection is formed.

Description

[Detailed Description of the Invention] A" Dorori (Industrial Application Field) The present invention relates to a thin-walled steel pipe, particularly a thin-walled steel pipe used to form an annular chevron at the end of the pipe for connecting thin-walled stainless steel pipes. This invention relates to a tube expansion device.

(Prior Art and Problems to be Solved by the Invention) A cross section of a conventional example of the structure of a pipe joint of a thin-walled steel pipe, particularly a thin-walled stainless steel pipe, published in Japanese Utility Model Application No. 59-107390, is shown in Fig. 9. As shown in the figure.

In this structure, a cap nut 31 is screwed into a joint 32 to compress an annular packing 33, and the packing 33 is attached to a thin-walled steel pipe.
4 to the annular chevron-shaped protrusion 34a formed in advance,
The joint 32 and the thin-walled steel pipe 34 are connected in a sealed manner.

However, in this structure, when the cap nut 31 is screwed into the joint 32, the packing 33 is attached to the contact surface 31a of the cap nut 31.
and the end face 32a of the joint 32,
The cap nut 31 is not fully screwed into the joint 32,
The joint 32 and the thin-walled steel pipe 34 cannot be connected in a sealed manner.

Furthermore, since the length of the thin-walled steel pipe 34 held by the cap nut 31 and the joint 32 is short, if the thin-walled steel pipe 34 is bent, it may immediately have a negative effect on the packing 33, leading to incomplete sealing. .

FIG. 3 is a cross-sectional view showing the structure of a pipe joint part that solves the problems of the above-mentioned conventional example.

In this structure, the male thread 21a of the bushing 21 is connected to the joint 22.
screw into the female thread 22a of the bushing 21, and
The packing 23 inserted into the packing mounting step 22b of the joint 22 is compressed at b, and the packing 23 is crimped onto the annular chevron-shaped protrusion 24a formed in advance on the thin-walled steel pipe 24, thereby sealingly connecting the fitting 22 and the thin-walled steel pipe 24. It is supposed to be done.

With this structure, the packing 23 does not protrude outward, so that the packing 23 can be reliably compressed, and the hermetically sealed connection between the joint 22 and the thin-walled steel pipe 24 can be ensured.

Furthermore, since the inner diameter portion 21c of the bushing 21 holds the thin-walled steel pipe 24 over a long distance, even if the thin-walled steel pipe 24 is bent, the sealing performance of the packing 23 is not adversely affected.

Next, a tube expansion device for forming the annular chevron-shaped protrusion 34a shown in FIG. 9 is published in Japanese Patent Publication No. 137-1981, and is shown in FIG.

In the tube expansion device shown in FIG. 10, a cap nut 44 that is screwed onto a tube expansion head 41 and forms an annular circumferential groove 43 for forming an annular chevron-shaped protrusion in a thin-walled steel pipe 42 is a cap nut shown in FIG. 31 and different from the bushing 21 shown in FIG. 3, this tube expansion device can be used to form an annular chevron-shaped protrusion 24a on the thin-walled steel pipe 24 of the pipe joint shown in FIG. I can't.

Note that when expanding the cap nut 31 in the pipe joint shown in FIG. 9 with the pipe expanding device shown in FIG. 10, the cap nut 44 is
The bushing 21 shown in Fig. 3 is also fitted into the thin-walled steel pipe 24 in advance during pipe expansion, and is used as a component of the pipe expansion device during pipe expansion. It is usually used as one part.

Furthermore, in the tube expansion device shown in FIG. 10, the amount of movement of the piston 45 for tube expansion is limited by the end surface 46a of the connector 46 coming into contact with the stepped surface 47a of the cylinder 47. Immediately after contact, the oil pressure within the cylinder 47 increases to the pressure of the oil pressure source, and a large force is applied between the end surface 46a and the step surface 47a and other components. This also applies when the thin-walled steel pipe 42 to be expanded has a relatively small diameter, and the hydraulic pressure required for expansion is relatively low. Therefore, the number of durable uses of this tube expansion device is reduced. , the lifespan is relatively short.

The present invention, as mentioned above, is an attempt to solve the problems that conventional pipe expansion devices cannot be used with improved pipe joint structures and that they have a relatively short lifespan.

Structure of the Invention (Means for Solving 11 Problems) In order to solve the above problems, the present invention is structured as follows.

A tube expansion device for forming an annular chevron-shaped protrusion at the end of a thin-walled steel pipe, the tube expansion device includes a piston with a piston rod fixed to one side and a compression coil spring that springs the other side of the piston. A guide bushing that guides the piston rod in a sealed manner is fitted and fixed on the piston rod side of the hydraulic cylinder, and a tube expansion head is connected to the piston rod side of the hydraulic cylinder, and A tube expansion rod is connected to the end, and a female thread is formed from the outside on the inner peripheral surface of the outer end of the tube expansion head, a large cylindrical hole into which the thin-walled steel pipe is fitted, and a small cylindrical hole into which the small diameter portion of the tube expansion rod is fitted. A bushing having a thread on the outer peripheral surface and a cylindrical hole in the inner peripheral surface into which the thin-walled steel pipe is inserted is screwed into the female thread, and the cylindrical hole is connected to the large cylindrical hole. Opposing tapered surfaces each having an annular circumferential groove with a chevron-shaped cross section are formed on the outer end thereof, and the tube expansion rod is fitted into the large-diameter portion inserted into the thin-walled steel pipe from the outer end and into the small cylindrical hole. It consists of a small diameter part and a connecting part connected to the outer end of the piston rod, and the outer diameter is equal to the large diameter part and the inner diameter fits into the small diameter part between the small cylindrical hole of the small diameter part and the large diameter part. A ring-shaped spacer and tube expansion rubber were fitted.

In this case, it is preferable that the hydraulic cylinder has a cover on the side housing the compression coil spring integrally formed with the cylindrical body.

Furthermore, a phototube switch marker is attached to either the outer end of the piston rod, the connection part of the tube expansion rod, or the connection tool between the outer end of the piston rod and the connection part of the tube expansion rod, and A phototube switch is attached to the cylinder to detect the amount of movement of the piston and stop the oil supply to the hydraulic cylinder, and when the phototube switch detects that the piston has moved a predetermined amount, a lamp and a buzzer are activated. It is advisable to notify in either or both.

In addition to the phototube switch, it includes a contact type switch mechanism such as a limit switch, or a non-contact type switch mechanism such as a Hall IC.

Furthermore, it is preferable to bring a part fixed to the piston rod, such as the connecting tool, into contact with the guide bushing to compensate for non-operation or improper use of the phototube switch, and to adjust the thin-walled steel pipe to the large diameter part. It is advisable to install an alignment device or to make the tube expansion rubber made of urethane rubber.

(Function) Since the thin-walled steel pipe expanding device of the present invention is constructed as described above, it functions as follows.

First, while fitting the end of the thin-walled steel pipe into the large diameter part of the tube expansion rod, insert it into the cylindrical hole of the bushing screwed into the tube expansion head.
Insert until the tube end contacts the step between the large cylindrical hole and the small cylindrical hole of the tube expansion head.

In this case, it is usual to use a bushing that is a component of the pipe joint of the thin-walled steel pipe.

Next, pressure oil is supplied to the piston rod side of the hydraulic cylinder. The piston moves while compressing the compression coil spring using pressure oil, and presses the spacer and tube expansion rubber between the large diameter part of the tube expansion rod and the small cylindrical hole of the tube expansion head, and the tube expansion rubber is compressed to shape the thin-walled steel pipe into an annular shape. It is extruded into the circumferential groove to form an annular chevron-shaped protrusion.

A marker for a phototube switch attached to either the outer end of the piston rod, the connection part of the tube expansion rod, or the connector that connects the outer end of the piston rod and the connection part of the tube expansion rod,
When the phototube switch attached to the body of the hydraulic cylinder detects this, the oil supply to the hydraulic cylinder is stopped and the piston stops moving.

Expansion work for thin-walled steel pipes is completed.

In this case, it is convenient for one operation if the phototube switch sends a signal to stop the oil supply, and at the same time a lamp and/or a buzzer is used to notify that the tube expansion operation is complete.

In addition, the movement of the piston is stopped by bringing a part fixed to the piston rod, such as a connecting tool, into contact with the guide bushing,
It can be used as a backup when the phototube switch does not work or if the phototube switch is used incorrectly and the piston cannot be stopped by the phototube switch.

In this case, the position of the part that comes into contact with the guide bushing is
Adjust it optimally depending on the size of the thin-walled steel pipe you are trying to expand.

Next, when the pressure oil system to the hydraulic cylinder is opened to allow oil to drain, the piston moves in the opposite direction due to the elastic force of the compression coil, and the large diameter part of the tube expansion rod and the small cylindrical hole of the tube expansion head are connected. widen the space between

As a result, the compressed expanded tube rubber returns to its original shape.

At this point, loosen and remove the bushing screwed onto the female thread of the tube expansion head, and pull out the thin-walled steel tube.

The thin-walled steel pipe has an annular chevron-shaped protrusion, and there is a bushing inside it, so screw the male thread of the bushing into the female thread of the joint with the seal attached, and tighten it to compress the bushing, and the thin-walled steel pipe and fittings can be connected in a sealed manner.

In addition, in the above-mentioned pipe expansion device of the present invention, if the cover on the side of the hydraulic cylinder containing the compression coil spring is formed integrally with the cylindrical body, the hydraulic cylinder becomes strong and there is less worry about external leakage. It is easy to process hydraulic cylinders.

Furthermore, if an alignment device for aligning the thin-walled steel pipe is attached to the large diameter portion of the tube expansion rod, the thin-walled steel tube can be held securely by the tube expansion device even if there are differences in the inner diameter dimensions of the thin-walled steel tube, and the tube can be expanded successfully.

Furthermore, when the tube expansion rubber is made of urethane rubber, the rubber has good returnability to its original shape and has a long life.

(Example) An example of the tube expanding device for thin-walled steel pipes according to the present invention will be described with reference to the drawings.

FIG. 1 is a longitudinal cross-sectional view showing one embodiment of the thin-walled steel pipe expanding apparatus of the present invention, and FIG. 2 is an enlarged vertical cross-sectional view of the portion shown in FIG. 1.

11s and FIG. 2, 1 is a tube expansion device, 2 is a thin-walled steel pipe, 3 is a hydraulic cylinder, and 4 is a piston.

4a is a piston rod, 5 is a compression coil spring, 6 is a guide bushing, 7 is a tube expansion head, 8 is a tube expansion rod, 9 is a connector, 10 is a bushing, 11 is a spacer, and 12 is a tube expansion rubber.

The tube expanding device 1 is for forming an annular chevron-shaped protrusion (the chevron-shaped protrusion 24a in the thin-walled steel pipe 24 in FIG. 3) on the tube end 2a of the thin-walled steel pipe 2. The tube expanding device 1 has a piston on one side. A guide that seals and guides the piston rod 4a with an O-ring 13 to the piston rod 4a side of the hydraulic cylinder 3, which incorporates a piston 4 to which a rod 4a is fixed and a compression coil spring 5 that springs the other side of the piston 4. A bush 6 is screwed and fixed to the hydraulic cylinder 3 in a sealed manner with an O-ring 14.

Further, a tube expansion head 7 is fitted into the piston rod 4a side of the hydraulic cylinder 3 and fixed with a pin 5, and a tube expansion rod 8 is connected to the outer end 4b of the piston rod 4a with a connector 9.

At the outer end of the tube expansion head 7, a female thread 7a is inserted from the outside on the inner peripheral surface.
, a large cylindrical hole 7b into which the thin-walled steel pipe 2 is fitted, and a small cylindrical hole 7c into which the small diameter portion 8a of the tube expansion rod 8 is fitted. A bushing 10 having a cylindrical hole 10b into which the thin-walled steel pipe 2 is inserted is screwed into the surface, and an annular circumferential groove 16 with a chevron-shaped cross section is formed at the connecting portion where the cylindrical hole 10b connects to the large cylindrical hole 7b. Opposing tapered surfaces 10c and 7d are formed.

Further, the tube expansion rod 8 has a large diameter portion 8b that fits into the thin-walled steel pipe 2 from the outer end, a small diameter portion 8a that fits into the small cylindrical hole 7c, and a connection that connects to the outer end 4b of the piston rod 4a via a connector 9. An annular spacer 11 having an outer diameter equal to the large diameter part 8b and an inner diameter fitting into the small diameter part 8a and a tube expanding rubber 1 are formed between the small cylindrical hole 7c of the small diameter part 8a and the large diameter part 8b.
2 is inset.

The hydraulic cylinder 3 has a cover 3a on the side housing the compression coil spring 5 integrated with a cylindrical body 3b.

17 is a phototube switch marker 18 is a phototube switch, and the phototube switch marker 17 is attached to the connector 9
A phototube switch 18 is attached to the body 3b of the hydraulic cylinder 3 to sense the amount of movement of the piston 4 and stop the oil supply to the hydraulic cylinder 3.

Note that when the phototube switch 18 detects that the piston 4 has moved by a predetermined amount, it may be notified by either or both of a lamp and a buzzer. Further, in addition to the phototube switch, it includes a contact type switch mechanism such as a limit switch, or a non-contact type switch mechanism such as a Hall IC.

Furthermore, the end face 9a of the connector 9 is brought into contact with the guide bush 6 to compensate for the inoperation or malfunction of the phototube switch.

4 and 6 are longitudinal sectional views showing other embodiments of the tube expansion rod, and FIGS. 5 and 7 are the XX cross section in FIG. 4 and the YY cross section in FIG. 6. In the embodiments shown in FIGS. 4 and 5, an alignment device 19 for aligning the thin-walled steel pipe is attached to the large diameter portion 8b.
A ball 19a is fixed to a rubber ring 19b and is pushed outward by the rubber ring 19b, and in the embodiment shown in FIGS. 6 and 7, a plunger 19c is pushed outward by a coil spring 19d. It's being fired. 8th
The figure shows that the distal end 8c of the tube expansion rod 8 has dl>
An alignment spring 19e made of d is wound around the centering spring 19e.

The expanding rubber tube 12 is made of urethane rubber, and 3c in the first @ is a connection port for supplying and discharging oil.

Next, the operation will be explained based on the embodiments shown in FIGS. 1, 2, and 4 to 7.

First, while fitting the pipe end 2a of the thin-walled steel pipe 2 into the large diameter part 8b of the pipe expansion rod 8, the pipe end is inserted into the large cylindrical hole 10b of the bushing 10 screwed into the pipe expansion head 7. 7b and the small cylindrical hole 7c until it comes into contact with the stepped portion 7e.

In this case, the bushing 10 is a bushing (bushing 2 in FIG.
1) is usually used.

Next, pressure oil is fed to the piston rod 4a side of the hydraulic cylinder 3. Piston 4 is compressed by compressed coil spring 5 by pressure oil.
while compressing the spacer 1 and the tube expansion rubber 12 between the large diameter portion 8b of the tube expansion rod 8 and the small cylindrical hole 7c of the tube expansion head 7.

The tube expanding rubber 12 is compressed and the thin walled steel tube 2 is moved into an annular circumferential groove 16.
to form an annular chevron-shaped protrusion (the annular chevron-shaped protrusion 24a in the third M).

When the phototube switch 18 attached to the body 3b of the hydraulic cylinder 3 senses the phototube switch marker 17 attached to the connector 9 that connects the outer end 4b of the piston rod 4a and the connection part 8c of the tube expansion rod 8, the hydraulic cylinder The oil supply to the piston 3 is stopped, the movement of the piston 4 is stopped, and the expansion work of the thin-walled steel pipe 2 is completed.

In this case, it is convenient if the phototube switch 18 sends a signal to stop the oil supply, and at the same time a lamp and/or a buzzer are used to notify that the tube expansion work has been completed.

In addition, the end surface 9a of the connector 9 fixed to the piston rod 4a is brought into contact with the guide bush 6 to stop the movement of the piston 4, thereby preventing the phototube switch 18 from working or the phototube switch 18 being used incorrectly. When the piston 4 cannot be stopped by the phototube switch 18, it can be used as a backup.

In this case, the position of the connector 9 brought into contact with the guide bush 6, that is, the distance A shown in FIG. 1, is optimally adjusted depending on the size of the thin-walled steel pipe 2 to be expanded.

Next, when the pressure oil system connected to the connection port 3c of the hydraulic cylinder 3 is opened to allow oil to be drained, the piston 4 moves to the right in the figure by the elastic force of the compression coil spring 5, expanding the pipe. Large diameter portion 8b of rod 8 and small cylindrical hole 7c of tube expansion head 7
widen the space between For this reason, the compressed tube expansion rubber ■2
returns to its original form.

Here, the bushing 10 screwed onto the female thread 7a of the tube expansion head 7 is loosened and taken out, and the thin-walled steel tube 2 is pulled out.

An annular projection is formed on the thin-walled steel pipe 2, and the inside thereof (
Since the bushing 10 is located on the right side of the figure, the female thread 22 of the joint 22 with the gasket 23 attached, as shown in FIG.
Attach the male thread 1 of the bushing 10 (bushing 21 in Figure 3) to a.
0a (male thread 21a in FIG. 3) is screwed in and tightened to compress the packing 23, and the thin-walled steel pipe 2 (thin-walled steel pipe 24 in FIG. 3) and the joint 22 can be connected in a sealed manner.

In the pipe expansion device l shown in FIG.
The hydraulic cylinder 3 becomes strong, there is little fear of external leakage, and the hydraulic cylinder 3 is easy to process.

Furthermore, if the alignment device 19 for aligning the thin-walled steel tube 2 is attached to the large diameter portion 8b of the tube expansion rod 8 as shown in FIGS. The thin-walled steel pipe 2 is securely held in the pipe expanding device 1, and the pipe can be expanded successfully.

Furthermore, if the tube expansion rubber 12 is made of urethane rubber, the tube expansion rubber 12 can easily return to its original shape and have a long life.

The thin-walled steel pipe expanding device of the present invention is constructed and operates as described above in detail, so that the following excellent effects can be obtained.

(2) An annular chevron-shaped protrusion can be easily formed on a thin-walled steel pipe for use in a pipe joint for a thin-walled steel pipe with an improved structure (as shown in FIG. 3).

■The bushing, which is a part of a pipe joint, can be used as it is as a part of a pipe expansion device to expand pipes.

■The hydraulic cylinder is strong and there is no risk of external leakage.

■The pressure applied to the hydraulic cylinder is at the height necessary for pipe expansion.
The single tube expansion device has a long life because it does not reach the height of the hydraulic power source.

■The expanded rubber tube also has a long life.

■Diameter expansion work for thin-walled steel pipes of the same size can be performed continuously, and for thin-walled steel pipes of different sizes, a pipe expansion head, a pipe expansion rod, a spacer, and a pipe expansion rubber are used.

If necessary, the pipe can be expanded by replacing the connector.

■The completion of pipe expansion work can be announced with a lamp or buzzer.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional view showing an embodiment of the thin-walled steel pipe expanding device of the present invention, FIG. 2 is a partially enlarged vertical sectional view of FIG. 1, and FIG. 3 is a longitudinal sectional view showing an embodiment of the thin-walled steel pipe expanding device of the present invention. 4, 6 and 8 are partial side views showing each side of the tube expansion rod of the tube expansion device for thin-walled steel pipes according to the present invention, and 5. 7 are cross-sectional views showing the xx section in FIG. 4 and the Y-Y cross section in FIG. 6, and FIG. 9 is a sectional view of a conventional pipe joint for thin-walled steel pipes, and The figure is a longitudinal cross-sectional view showing a conventional tube expansion device for thin-walled steel pipes. 1... Pipe expansion device 2... Thin wall steel pipe 2a...
・Pipe end 3...Hydraulic cylinder 3a...Cover 3b...Body 4...Piston
4a... Piston rod 4b... Outer end
5... Compression coil spring 6... Guide bushing
7...Tube expansion head 7a...Female thread 7b
...Large cylindrical hole 7c...Small cylindrical hole 7d...
Tapered surface 8...Tube expansion rod 8a...Small diameter part 8b...Large diameter part 8c...Connection part 9...
Connection tool 10... Bush 10a... Male thread 10b... Cylindrical hole 10c... Tapered surface 11... Spacer 12... Tube expansion rubber
16... Annular circumferential groove 17... Marker for phototube switch 18... Phototube switch 19... Aligning device 1 Figure 3 Figure 4 Figure 6 Figure 5 Figure 7 Figure 8 figure

Claims (9)

[Claims] (1) A tube expansion device for forming an annular chevron-shaped protrusion at the end of a thin-walled steel pipe, the tube expansion device comprising a piston having a piston rod fixed to one side and a compression coil that springs the other side of the piston. A guide bush that guides the piston rod in a sealed manner is fitted and fixed to the piston rod side of a hydraulic cylinder containing a spring, and an expansion head is connected to the piston rod side of the hydraulic cylinder. A tube expansion rod is connected to the outer end of the tube expansion head, and a female thread is formed from the outside on the inner peripheral surface of the outer end of the tube expansion head, a large cylindrical hole into which the thin-walled steel tube is fitted, and a small cylindrical hole into which the small diameter portion of the tube expansion rod is fitted. A bush having a thread on the outer peripheral surface and a cylindrical hole in the inner peripheral surface into which the thin-walled steel pipe is inserted is screwed into the female thread, and the cylindrical hole is connected to the large cylindrical hole. The connecting portion is formed with opposing tapered surfaces that are configured with an annular circumferential groove with a chevron-shaped cross section, and the tube expansion rod is inserted into the large diameter portion that fits into the thin-walled steel tube from the outer end, and into the small cylindrical hole. Consisting of a small diameter part to be fitted into and a connecting part connected to the outer end of the piston rod,
A thin-walled steel pipe characterized in that an annular spacer whose outer diameter is equal to the large diameter part and whose inner diameter fits into the small diameter part and an expanding rubber are fitted between the small cylindrical hole of the small diameter part and the large diameter part. tube expansion device. (2) The thin-walled steel pipe expanding device according to claim 1, wherein the hydraulic cylinder has a cover on the side housing the compression coil spring integrally formed with a cylindrical body. (3) Attach a phototube switch marker to either the outer end of the piston rod, the connection part of the tube expansion rod, or the connection tool between the outer end of the piston rod and the connection part of the tube expansion rod, and 3. The thin-walled steel pipe expanding device according to claim 1, wherein a phototube switch is mounted on the body to sense the amount of movement of the piston and stop the oil supply to the hydraulic cylinder. (4) The device for expanding thin-walled steel pipes according to claim 3, wherein when the phototube switch detects that the piston has moved by a predetermined amount, a notification is provided by one or both of a lamp and a buzzer. (5) The thin-walled steel pipe expansion device according to claim 4, which includes a contact type switch mechanism such as a limit switch or a non-contact type switch mechanism such as a Hall IC in addition to the phototube switch. (6) A device for expanding a thin-walled steel pipe according to any one of claims 3 to 5, wherein a portion fixed to the piston rod, such as the connecting tool, is brought into contact with the guide bush to compensate for non-operation or poor use of the phototube switch. . (7) A device for expanding a thin-walled steel pipe according to any one of claims 1 to 6, wherein an aligning device for aligning the thin-walled steel pipe is attached to the large diameter portion. (8) The tube expansion device for thin-walled steel pipes according to any one of claims 1 to 7, wherein an alignment spring is provided on the tube expansion rod as the alignment device. (9) The tube expansion device for thin-walled steel pipes according to any one of claims 1 to 8, wherein the tube expansion rubber is made of urethane rubber.