JP6580935B2 - Pipe expansion machine - Google Patents

Description

  The present invention relates to a tube expander for inserting inside a metal tube and expanding the tube.

In general, a welded pipe typified by a UOE steel pipe welds the inner and outer surfaces of the pipe, and the roundness and straightness of the pipe deteriorate due to residual stress due to the thermal effect of welding. Therefore, in order to remove residual stress and correct roundness and straightness, tube expansion processing is performed.
About this pipe expansion process, it describes in the nonpatent literature 1, for example. FIG. 1A and FIG. 1B are based on the figures disclosed in Non-Patent Document 1. FIG. In the pipe expansion process, the pipe expansion head 13 of the pipe expansion machine 100 is passed through the inside of the steel pipe 1 subjected to submerged arc welding from the inner and outer surfaces. Next, as shown in FIG. 1 (b), when the cone 17 of the tube expansion head 13 is pulled in the axial direction, the jaw 18 spreads in the radial direction by the wedge action of the cone 17 and the jaw 18, and the outside of the jaw 18. A die 19 attached to squeezes the steel pipe 1.
In such tube expansion processing, as shown in FIG. 1B, the jaw 18 expands in the radial direction by sliding on a sliding surface that is a contact surface between the cone 17 and the jaw 18.

In recent years, as the strength of the steel pipe 1 increases, an excessive force is applied when the cone 17 is pulled in the axial direction, and the surface pressure also increases on the sliding surface between the cone 17 and the jaw 18. Seizure occurs on the sliding surfaces of the cone 17 and the jaw 18. If seizure occurs, tube expansion becomes impossible. Such seizure is likely to occur in a relatively short period of time as the strength of the steel pipe is increased. When seizure occurs, maintenance of the sliding surfaces of the cone 17 and the jaw 18 is required.
On the other hand, Patent Document 1 proposes that a hardened layer having a depth of 0.05 to 1.5 mm is formed on the surface layer of the cone 17 by nitriding. In Patent Document 2, it is proposed that the hardness of the jaw 18 is HRC 45 to 52 and the surface is subjected to nitrosulphurizing treatment. Patent Document 3 proposes supplying lubricating oil to the sliding surfaces of the cone 17 and the jaw 18 in order to reduce seizure on the sliding surfaces of the cone 17 and the jaw 18.

Japanese Patent Laid-Open No. 01-299723 JP 05-195158 A JP 2007-284519 A

Steel Handbook Volume 3 (2), 4th Edition, 12.4.6

However, the seizure of the sliding surface cannot be sufficiently prevented if the cone is hardened as in Patent Document 1 and the hardness difference from the jaw is about 20 HS. This is because if the hardness difference is 20 HS or less, the abrasive wear between the hard member and the soft member is small. Further, as in Patent Document 2, if the jaw is hardened and the hardness difference from the cone is about 45 to 50 HS, the seizure cannot be sufficiently prevented. This is because if the hardness difference is 45 HS or more and the absolute value of the hardness value is low, the abrasive wear is too large between the hard member and the soft member. And just supplying lubricating oil like patent document 3 cannot fully prevent. This is because an oil film of lubricating oil is not always generated on the entire sliding contact surface.
Here, in this specification, HS refers to the hardness HS according to JIS Z 2246 Shore hardness test.
This invention is made | formed with respect to such a problem, and it aims at providing the pipe expander which can make the maintenance interval longer.

Inventors repeated earnest research in order to achieve the above-mentioned subject. As a result, the present inventors have found that the above problems can be solved by forming a hard film by a method such as PVD (Physical Vapor Deposition) or CVD (Chemical Vapor Deposition), and have completed the present invention.
That is, one embodiment of the present invention is a tube expansion machine for expanding a tube by inserting the tube into a metal tube, and is attached to the shaft body coaxially with a shaft body that can advance and retreat in the axial direction. A cone having a tapered surface whose diameter increases toward one direction in the axial direction; and a diameter-expanding segment having a sliding contact surface slidable with the tapered surface along the axial direction. Alternatively, a physical vapor deposition film made of a TiN film or a TiAlN film is formed on one surface of the sliding contact surface, and the hardness of the surface on which the physical vapor deposition film is formed is 150 HS or more, The hardness difference between the hardness of the taper surface and the hardness of the sliding contact surface is in the range of 50 HS or more and 120 HS or less.

In the pipe expanding machine which is one embodiment of the present invention, one of the contact surfaces that slide during pipe expansion is formed by a physical vapor deposition method using a hard film made of a TiN film or a TiAlN film. Since the hardness of the formed surface (tapered surface or sliding contact surface) is 150 HS or more and the hardness difference with the other contact surface is 50 to 120 HS, it is possible to suppress seizure of the sliding portion.
Thus, in one embodiment of the present invention, since the hardness level between the contact surfaces is high, the durability of wear is high, and the maintenance interval can be made longer. This also reduces the frequency of replacement, leading to lower costs.

It is a figure explaining the structure of a pipe expander, (a) is a figure which shows the whole structure of a pipe expander, (b) is a figure which shows the structure of a pipe expansion head. It is a mimetic diagram for explaining a pipe expansion head of a pipe expansion machine concerning a 1st embodiment based on the present invention. It is sectional drawing cut | disconnected in the axial direction which shows the structure of the cone which concerns on 1st Embodiment based on this invention. It is a figure which shows typically the positioning of each hardness difference in the contact surface between a liner and a jaw, and the relationship of those hardness differences. It is a schematic diagram for demonstrating the pipe expansion head of the pipe expansion machine which concerns on 2nd Embodiment based on this invention. It is a schematic diagram which shows the cone which concerns on 2nd Embodiment based on this invention, (a) is sectional drawing cut | disconnected along the axial direction, (b) is a cross section cut | disconnected by the axial direction. It is a schematic diagram which shows the pull-out test machine for research experiments. It is a figure which shows the result of the pull-out test of a research experiment.

Embodiments of the present invention will be described below with reference to the drawings. In addition, this invention is not limited to the following embodiment. In this embodiment, a steel pipe will be described as a metal pipe, but a pipe made of another metal is also applicable.
<First embodiment>
(Constitution)
The basic configuration of the pipe expander of this embodiment is the same as that of a conventional pipe expander represented by FIG. That is, the pipe expander 100 includes a pipe expander main body 14, an axial infeed 15, and a cross feed 16, as shown in FIG.
The pipe expander main body 14 includes a cylinder 11, a horn 12, and a pipe expansion head 13.
The cross feed 16 conveys the steel pipe 1 in a direction orthogonal to the paper surface by a walking beam method. The axial infeed 15 pushes the steel pipe 1 conveyed by the cross feed 16 into the pipe expander main body 14 side.

The pipe expansion head 13 is inserted into the steel pipe 1 when the steel pipe 1 is conveyed to the side of the pipe expander main body 14. The cylinder 11 pulls the tube expansion head 13 provided at the tip of the horn 12 in the axial direction. The pipe expansion head 13 expands the diameter of the steel pipe 1 from the inside by expanding the outer circumference in the radial direction.
As shown in FIG. 1B, the tube expansion head 13 has a cone 17, a jaw 18, and a die 19. The cone 17 is coaxially attached to the distal end side of the draw bar 21 connected to the cylinder 11. The draw bar 21 constitutes a shaft body. The jaw 18 and the die 19 constitute an enlarged diameter segment.

The cone 17 has a tapered surface 17a that increases in diameter toward one side in the axial direction. In the present embodiment, as in the cross-sectional view shown in FIG. 3, the outer peripheral surface of the cone 17 is exemplified as a truncated pyramid shape. In FIG. 3, since the case of a regular decagon is illustrated, the taper surface 17a faces in 10 directions. Each segment constituting a jaw 18 described later is disposed on each tapered surface 17a so as to face each other in the radial direction. The cone 17 moves in the axial direction as the cylinder 11 expands and contracts.
The jaw 18 is composed of a plurality of segments arranged in the circumferential direction, and the plurality of segments are combined and arranged in a tubular shape. A cone 17 is arranged inside the tubular jaw 18. The inner side of the jaw 18 is arranged in a shape along the outer periphery of the cone 17. The inner peripheral surface of each segment constituting the jaw 18 is opposed to each tapered surface 17a of the cone 17 in the radial direction, and a slidable contact surface 18a is formed that is slidable in the axial direction. ing. Here, the tapered surface 17a and the sliding contact surface 18a may be referred to as sliding surfaces.

A die 19 is attached to the outer peripheral surface of each segment constituting the jaw 18. The outer peripheral surface of the die 19 comes into contact with the inner surface of the tube as the diameter increases.
The lubricating oil supply pipe 20 supplies lubricating oil to the sliding surfaces of the cone 17 and the jaw 18.
A physical vapor deposition film 171 made of a TiN film or a TiAlN film is formed on the tapered surface 17a of the cone 17 of the present embodiment. The taper surface 17a on which the physical vapor deposition film 171 is formed has a hardness of 150 HS or more.
In the present embodiment, the hardness of the slidable contact surface 18a of the jaw is set to a hardness smaller than the hardness of the tapered surface 17a by a range of 50 HS or more and 120 HS or less. For example, if the taper surface 17a has a hardness of 150 HS , the sliding contact surface 18a has a hardness in the range of 30 HS to 100 HS .

However, it is preferable to adjust the hardness of the sliding contact surface 18a to be 70HS or more. That is, if the hardness of the taper surface 17a is 150 HS , the hardness of the sliding contact surface 18a is preferably in the range of 70 HS or more and 100 HS or less. If the hardness of the taper surface 17a is 180 HS , the hardness of the sliding contact surface 18a is preferably in the range of 70 HS to 130 HS .
The hardness of the jaw 18 may be adjusted by using a high strength steel such as a known carbon alloy steel so that the hardness becomes 70 HS or more.

(Operation other)
In the pipe expander 100 configured as described above, the cone 17 moves in the axial direction by expansion and contraction of the cylinder 11, so that they ride on the sliding surfaces (tapered surface 17 a and sliding contact surface 18 a) between the cone 17 and the jaw 18. (Wedge action). As a result, the dies 19 provided on the outer periphery of the jaws 18 radially expand to the same diameter. Since the outer peripheral surface of the die 19 abuts coaxially with the inner peripheral surface of the steel pipe 1, the steel pipe 1 is expanded from the inner side by expanding the die 19 radially, and the diameter of the steel pipe 1 is increased.
In the conventional pipe expander, seizure occurs between the tapered surface 17a of the cone 17 and the sliding contact surface 18a of the jaw 18 after a short period of use. At this time, seizure generated on the surface of the cone 17 requires replacement of the cone 17. Since the cone 17 is expensive, replacement of the cone 17 significantly increases the manufacturing cost of the steel pipe.

In contrast, in the present embodiment, a physical vapor deposition film 171 that is a hard film having a hardness of 150 HS or more is formed on the tapered surface 17a of the cone 17 by a physical vapor deposition method, and the physical vapor deposition film 171 is formed. Further, the hardness of the tapered surface 17a is set to 150 HS or more, and a hardness difference of 50 to 120 HS is provided between the tapered surface 17a and the sliding contact surface 18a. As a result, since the hardness level between the contact surfaces is high, the wear durability is high, and seizure of the sliding portion can be suppressed. For this reason, it becomes possible to make the maintenance interval longer. This also reduces the replacement frequency of the cone 17 and the like, leading to low costs.
Here, it is necessary to heat the tapered surface 17a of the cone 17 in order to form a hard film. In order to suppress such deformation in the cooling process after heating and film formation, in this embodiment, the physical vapor deposition film 171 that is a hard film is formed by a physical vapor deposition method with a relatively low heating temperature. To do.

  The physical vapor deposition film 171 preferably has a hardness of 1470 HV or higher so as to withstand the surface pressure at the contact surface. The hardness of the physical vapor deposition film 171 is not particularly limited. However, the hardness of the physical vapor deposition film 171 is desirably 200 OHV or less because it becomes brittle when the hardness of the film becomes too high. Here, the hardness according to the JIS Z 2244 Vickers hardness test was used as an index. In addition, about the hardness of a film | membrane, the cross section of tools, such as a cone which formed the film | membrane, can be grind | polished, and micro Vickers hardness measurement can be implemented about the film | membrane cross section obtained in that way, and it can be set as film | membrane hardness.

Next, the reason why the range of the hardness difference between the sliding tapered surface 17a and the sliding contact surface 18a is limited to a range of 50 HS or more and 120 HS or less will be described.
If the hardness difference is small, not only the soft side surface but also the hard film may be damaged. Therefore, the lower limit of the hardness difference is set to 50 HS. Further, when the hardness difference is large, if the hardness of the soft side surface is low and the wear amount on the soft side is large, a step is generated on the outer periphery of the die 19 and the shape is transferred to the steel pipe 1 to impair the dimensional shape of the product. It becomes. Therefore, the upper limit of the hardness difference is set to 120HS.
Here, in the above description, the case where the physical vapor deposition film 171 is formed on the tapered surface 17a of the cone 17 has been described. The surface on which the physical vapor deposition film 171 is formed may be a slidable contact surface 18a on the jaw side.

However, slight thermal deformation may occur even when physical vapor deposition is applied to the formation of the hard film. From this point of view, when the physical vapor deposition film 171 of the cone 17 is formed, the lubricating oil supply pipe 20 and the draw bar 21 cannot be attached, and a dimension finishing process for these portions may be necessary. On the other hand, when the physical vapor deposition film 171 is formed on the slidable contact surface 18a of the jaw 18, it is only necessary to finish the dimensions of the smooth surface to which the die 19 is attached. Therefore, the finishing process is simple and parts can be easily manufactured. It is.
However, when the soft side surface is worn and the dimensional shape of the product is damaged, these members are manufactured again. From this viewpoint, in order to suppress wear on the cone 17 side which is a large member, it is better to perform a hard film treatment on the cone 17.

Next, the reason why the hardness of the soft side surface is preferably 70 HS or more will be described.
Contact pressure acts on the contact surface between the cone 17 and the jaw 18. At this time, if the contact is localized, the contact pressure at that portion increases, and plastic deformation may occur on the soft side surface. In order to prevent such plastic deformation, the member on the soft side needs to have a predetermined strength. From such a viewpoint, the hardness of the sliding surface on the soft side is set to 70 HS or more.
Here, FIG. 4 is a diagram schematically showing the positions of the respective hardness differences between the hard side and the soft side and the relationship between the hardness differences. The hardness difference HS which is the two enclosures in FIG. 4 is that the hardness difference level is lower, the hardness on the hard side changes due to the hardness difference of 20 to 50 HS when the soft side hardness is changed from 40 to 60 HS. FIG. The higher hardness difference level is an enclosure diagram in which the hardness on the hard side is changed due to the hardness difference of 50 to 120 HS when the hardness on the soft side is changed from 70 to 130 HS.

  Accordingly, when the physical vapor deposition film 171 is formed and the hardness on the hard side is set to 150 HS or higher, and the hardness level is increased to 70 HS or higher on the soft side, the wear resistance on the soft side is also increased. Furthermore, if the hardness difference is adjusted to a range of 50 to 120 HS, the replacement frequency can be further suppressed. Note that the physical vapor deposition film 171 formed by the physical vapor deposition method has a low processing temperature, and thus is less distorted and is desirable compared to other hard coatings.

<Second embodiment>
Next, a second embodiment will be described with reference to the drawings. In addition, the same code | symbol is attached | subjected and demonstrated to the member similar to 1st embodiment.
The basic configuration of this embodiment is the same as that of the first embodiment.
As shown in FIG. 5, the cone 17 of the present embodiment includes a cone body 170 and a liner 172 that is detachably attached to the outer peripheral surface of the cone body 170. The surface of the liner 172 forms a tapered surface 17a. A physical vapor deposition film 171 is formed on the surface of the liner 172.
Each liner 172 is fixed to the cone body 170 with bolts 30 as shown in FIG.
Here, as shown in FIG. 6B, when the cone main body 170 has a regular decagonal shape, each side of the regular decagon is composed of one segment 17A. The segment 17A is constituted. As shown in FIG. 3B, a groove 170a extending in the axial direction of the cone 17 is formed on each surface on the outer peripheral side of the cone 17 of each segment 17A. The groove 170a is deepest at the center, and has stepped surfaces 170b at both ends.

5 and 6, the liner 172 has a plate shape extending in the axial direction of the cone 17, and two liners 172 are fixed to each segment 17 </ b> A of the cone body 170. In the cone 17 shown in FIGS. 5 and 6, the liner 172 is fixed by the bolt 30 along each step surface 170 b. The liner 172 is detachable by the bolt 30.
Here, the bolt 30 is an example of a fixture that can removably fix the liner 172 on the cone body 170, and the fixture is not limited to the bolt 30.

In the present embodiment, the liner 172 does not have to be present on the entire contact surface with the jaw 18 on the outer surface of the cone 17, and if there is no problem due to seizure on the cone 17, a part of the contact surface is provided. There may be a region where the liner 172 does not exist.
This liner 172 is a simple plate-like member, and it is easy to suppress thermal deformation in the heating and cooling processes for the hard film treatment. Therefore, when the same hard film as that of the first embodiment is formed on this liner 172 The finishing process becomes unnecessary. Even in this case, the accuracy is improved by using the physical vapor deposition film 171 as the hard film.
Here, the case where the liner 172 is attached to the cone body 170 is taken as an example, but the same effect can be obtained even if the jaw 18 side is used as the liner 172. However, since the cone 17 is thicker, it is easier to attach with the bolt 30.
Other functions and effects are the same as those of the first embodiment.

<Example 1>
Next, examples of the present invention will be described.
As an example of the present invention, an experiment was conducted using a pull-out tester for research experiments shown in FIG.
The test by the pull-out tester is a test in which the plate test piece 51 is pulled out with a pull-out load F in a state where the plate test piece 51 is pressed by the bead tool 50 with a predetermined pressing force N.
The pressing pressure N in the test was a surface pressure of 20 kgf / mm ² .
Here, in this test, if the plate test piece 51 is regarded as the soft side jaw 18 in FIG. 1 and the bead tool 50 is regarded as the hard side cone 17 in FIG. 1, this test can evaluate the same sliding behavior as that of the pipe expander. .
In this example, the hardness of the plate test piece 51 was 80 HS. Further, as the hardness of the portion of the bead tool 50 that comes into contact with the plate test piece 51, 100HS, 130HS, and 200HS were prepared, and a pulling test was performed.

  The bead tool hardness of 130HS was set to 130HS by forming a physical vapor deposition film TiN (film hardness 1470HV) on the surface. The bead tool hardness of 200 HS was set to a hardness of 200 HS by forming a film on the surface with a physical vapor deposition film TiAlN (film hardness 2000 HV). The film thickness was in the range of 2-4 μm. The hardness of the coating is measured by micro Vickers hardness measurement on the cross section of a tool such as a cone on which the coating is formed or the cross section of a test piece on which the coating is formed under the same conditions. It was calculated by carrying out. The Vickers hardness test of the film was performed according to JIS Z 2244 (2009) Vickers hardness test-test method. Then, the friction coefficient between the plate test piece and the sliding contact surface 18a of each bead tool was investigated.

The hardness of a bead tool having a physical vapor-deposited film formed on the surface is a known Vickers hardness HV measured according to the JIS Z 2244 (2009) Vickers hardness test-test method with respect to the film surface. The following equation (1) obtained by linear approximation from the hardness conversion table was extrapolated in the direction in which the Vickers hardness is high, and the converted Shore hardness VHS was defined as the Shore hardness HS.
VHS = 0.0919HV + 17.305 (1)
Here, VHS is converted Shore hardness, and HV is Vickers hardness.

Then, the friction coefficient between the plate test piece and the sliding contact surface 18a of each bead tool was investigated.
The test results are shown in FIG.
As can be seen from FIG. 8, when the hardness of the bead on the hard side is 100 HS (a hardness difference of 20 HS from the plate test piece), the friction coefficient is as high as 0.4, and seizure is likely to occur in a relatively short time. I understand that.
On the other hand, when the hardness of the bead was changed to 130 HS (hardness difference of 50 HS with respect to the plate test piece), it was found that the friction coefficient decreased and seizure hardly occurred. Furthermore, when the hardness of the bead was changed to 200 HS (a hardness difference of 120 HS with respect to the plate test piece), it was found that the friction coefficient was further reduced and seizure was less likely to occur. The tube can be expanded smoothly.
Thus, it was confirmed that seizure could be suppressed by setting the hardness of the cone 17 to 150 HS or more and the hardness difference from the jaw 18 to 50 to 120 HS.
However, if the hardness is further increased, the material of the cone 17 becomes brittle, and it is estimated that it causes peeling and seizure.

DESCRIPTION OF SYMBOLS 1 Steel pipe 11 Cylinder 12 Horn 13 Tube expansion head 14 Tube expansion machine main body 15 Axial infeed 16 Cross feed 17 Cone 17A Segment 17a Tapered surface 18 Jaw (expansion segment)
18a Sliding contact surface 19 Die 20 Lubricating oil supply pipe 21 Draw bar (shaft)
30 bolt 50 bead tool 51 plate test piece 100 tube expander 170 cone body 171 physical vapor deposition film 172 liner

Claims (4)

A pipe expander for inserting the pipe inside the metal pipe and expanding the pipe;
An axial body that can advance and retract in the axial direction;
A cone having a tapered surface that is coaxially attached to the shaft body and has a diameter that increases in one direction of the axial direction;
A diameter-expanding segment having a sliding surface slidable with the tapered surface along the axial direction,
A physical vapor deposition film made of a TiN film or a TiAlN film is formed on one surface of the tapered surface or the sliding contact surface, and the hardness of the surface on which the physical vapor deposition film is formed is 150 HS or more. And
The hardness difference between the hardness of the tapered surface and the hardness of the sliding contact surface is in the range of 50 HS or more and 120 HS or less ,
Of the taper and the sliding surface, the surface of the surface on which the physical vapor deposition film is not formed has a hardness of 70 HS or more .   The tube expansion machine according to claim 1, wherein the physical vapor deposition film is formed on the sliding contact surface.   The tube expansion machine according to claim 1, wherein the physical vapor deposition film is formed on the tapered surface.   The tube expansion machine according to claim 3, wherein the cone has a detachable liner, and a surface of the liner that can face the sliding surface is the tapered surface.

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