KR102136352B1 - Method of making flexible joint - Google Patents

Abstract

The method of manufacturing a telescopic joint according to the present invention prepares a circular corrugated pipe, surrounds a braid on the outer circumferential surface of the corrugated pipe, inserts a positioning tube at one end of the braid, and spreads a tool inside the corrugated pipe. Inserting, expanding the corrugated tube and braid using a diffusion tool, and separating the diffusion tool from the interior of the corrugated tube.

Description

Method of manufacturing new joint pipes{METHOD OF MAKING FLEXIBLE JOINT}

The present invention relates to a method for manufacturing a stretchable joint made without performing welding in order to semi-permanently bind components of different materials in the field of expansion joint.

In general, expansion joints are designed to safely absorb heat induced expansion or contraction of building materials to absorb vibrations of building materials due to ground subsidence or earthquakes, to hold building materials together, or to enable movement of building materials. It is one assembly. Here, the expansion joint is commonly found in buildings, bridges, sidewalks, train tracks, piping systems, ships, and other structures.

In particular, among the types of expansion joints, the flexible joint is a flexible joint pipe positioned between pipes and absorbing vibration transmitted from the outside of the pipe to prevent damage and deformation of the pipe. Since the flexible joint requires operability, pressure resistance, and corrosion resistance to be used in a piping system, it is structurally composed of a metal tube, a metal wire weave braid, and a metal flange.

The metal tube is made of stainless steel to increase elasticity and is formed by corrugated molding, and increases bending resistance and flexibility to reduce external vibration. The metal wire woven braid surrounds the metal tube and limits the longitudinal extension of the metal tube and protects the metal tube from external impact. The metal flange is fitted at both ends of the metal tube and the metal wire weave braid and is made of iron to freely connect with various connectors of the pipe.

In the flexible joint, the metal tube and the metal wire weave braid are exposed to tungsten inert-gas arc welding (TIG) using a tungsten electrode in an inert gas atmosphere to bond with a metal flange. The tungsten welding rod is not consumed during welding and supplies only current to the metal tube, metal wire weave braid and metal flange. Although the tungsten welding rod supplies a small current, the tig welding generates a stable arc and is suitable for thin welding, for example, welding of piping.

However, during the welding of the metal tube, the metal wire woven braid and the metal flange, the teak welding melts and bonds a heterogeneous material of stainless and iron on the inner side wall of the metal flange. When the metals of different materials are joined, the standard potential difference of the ionization tendency of the metals of the different materials is the potential difference corrosion in unstable metals with a high ionization tendency even if no special corrosion atmosphere is applied to the joint according to the galvanic corrosion principle. First cause.

The potential difference corrosion may gradually oxidize the metal flange during the service life of the flexible joint, thereby creating a gap between the metal flange, the metal tube and the metal wire weave braid, thereby deteriorating the performance of the flexible joint. Through this, while the building faces, concrete slabs and pipings repeatedly expand and contract due to temperature rises and temperature drops due to seasonal changes or other heat sources, the flexible joint can be used with building faces, concrete slabs and It does not sufficiently absorb the expansion and contraction of the pipes and thus does not prevent cracks on the building surfaces, concrete slabs and pipes.

The flexible joint is disclosed as a prior art in Korean Patent Publication No. 10-2011-0020501.

Korean Patent Publication No. 10-2011-0020501

The present invention has been devised to solve the problems of the prior art, and does not expose dissimilar metals to TIG welding, thereby preventing potential difference corrosion in dissimilar metals and thereby manufacturing a flexible joint pipe suitable for maintaining a constant service life. The purpose is to provide.

The method of manufacturing a telescopic joint according to the present invention prepares a circular corrugated pipe, surrounds a braid on an outer circumferential surface of the corrugated pipe, inserts a positioning pipe at one end of the braid, and is inside the corrugated pipe. Inserting a diffusion tool, using the diffusion tool to expand the corrugated tube and the braid, and separating the diffusion tool from the inside of the corrugated tube, wherein the corrugated tube and the braid, after expansion of the diffusion tool , It is characterized in that it is in close contact with the inner side wall of the positioning tube and has curved portions on both sides of the positioning tube, and has an uneven or uneven shape below the positioning tube.

The corrugated pipe is formed into a tubular shape using a stainless plate and may have a pleated portion on one portion and a smooth portion forming a relatively flat shape compared to the pleated portion on the other portion.

Surrounding the braid on the outer circumferential surface of the corrugated pipe is prepared by weaving the braid with a stainless wire in a tubular shape, along the longitudinal direction of the corrugated pipe, the corrugated portion of the corrugated pipe and the smooth It includes surrounding the part with the braid, the corrugated pipe and the braid may have the same length along the longitudinal direction of the corrugated pipe.

The method of manufacturing the expansion joint may further include forming an iron spring or a plurality of rubber O-rings between the corrugated pipe and the braid. The iron spring or the plurality of rubber O-rings may be fitted to the smooth portion of the corrugated pipe.

The inner wall of the positioning tube may have a relatively flat shape compared to the wrinkled portion of the corrugated pipe.

The inner wall of the positioning tube may form a relatively flat shape relative to the wrinkled portion of the corrugated tube between the annular engaging jaws and the engaging jaws at both inlets of the positioning tube.

The inner wall of the positioning tube may have a plurality of concave portions or convex portions.

The inner wall of the positioning tube may include a plurality of first teeth having a first triangular inclined plane in one direction, and a plurality of second teeth having a second triangular inclined plane in the other direction.

The fitting of the positioning tube to the one end of the braid may include fitting the positioning tube to the corrugated tube and the braid through the one end of the braid on the smooth portion of the corrugated tube.

The diffusion tool is a donut-shaped elastic member, a rod inserted into an opening of the elastic member and serving as a horizontally movable piston, a moving stopper fixed to the rod on one side of the elastic member, and the other side of the elastic member In may include a rod guider that is movable relative to the rod.

Using the diffusion tool to expand the corrugated pipe and the braid, the elastic member of the diffusion tool is brought into contact with the corrugated pipe inside the corrugated pipe using the diffusion tool, and toward the opposite side of the elastic member. The rod is moved forward relative to the rod guider, and during the forward movement of the rod, the volume of the elastic member is inflated between the moving stopper and the rod guider toward the inner wall and both sides of the positioning tube. It may include pushing the corrugated pipe and the braid using an elastic member.

The length of the elastic member may be formed larger than the length of the positioning tube when viewed along the longitudinal direction of the corrugated pipe.

The elastic member pushes the corrugated pipe and the braid through a central region to compress the corrugated pipe and the braid on the inner wall of the positioning pipe, and pushes the corrugated pipe and the braid through both edges of the positioning pipe. It may act to form the curved portion on the corrugated pipe and the braid on both sides.

Separating the diffusion tool from the inside of the corrugated pipe moves the rod relative to the rod guider from the opposite side of the elastic member toward the elastic member, and during the retracting movement of the rod, the movement Between the stopper and the rod guider, shrink the volume of the elastic member toward the center of the corrugated pipe to space the elastic member from the corrugated pipe, and use the rod of the spreading tool to spread the tool from the inside of the corrugated pipe It may include removing.

The positioning tube may include stainless steel or iron and may be thicker than the corrugated tube.

The present invention, without exposing the corrugated pipe, braid and positioning tube to TIG welding, actively uses both the shape of the inner wall of the positioning tube and both sides of the positioning tube, and the corrugated tube and braid in one attempt to process the corrugated tube and braid Since the and positioning tube are quickly connected, the expansion joint tube can be simply manufactured.

The present invention makes it difficult to separate the corrugated pipe and the braid from the positioning pipe by forming a'M' or'W' shaped bend around the positioning pipe without using TIG welding and binding the corrugated pipe, the braid and the positioning pipe Since it is maintained semi-permanently, the number of manufacturing steps can be reduced to reduce the manufacturing cost of the expansion joint.

The present invention prevents the potential difference corrosion between the corrugated pipe, the braid and the positioning pipe by not exposing the corrugated pipe, the braid and the positioning pipe to TIG welding, so that the use of the expansion joint pipe depends on the metal material of the corrugated pipe, the braid and the positioning pipe It can keep the lifespan constant.

The present invention, by pressing the corrugated pipe and the braid to the positioning tube along the shape of the inner side wall of the positioning tube and forming the corrugated pipe and the braid on both sides of the positioning tube to form a curved portion in the corrugated pipe and the braid, so that By using a side wall and a curved portion of the corrugated pipe and the braid, the braid can be properly fixed between the positioning pipe and the corrugated pipe to maintain the durability of the expansion joint.

1 to 5, and 7 are schematic diagrams illustrating a method of manufacturing a stretchable joint according to the present invention.
6 is a schematic view illustrating a manufacturing method according to a first modified example of the expansion joint of FIG. 5.
8 is a schematic view illustrating a manufacturing method according to a second modified example of the expansion joint of FIG. 5.
9 to 11 are schematic diagrams illustrating a manufacturing method according to a third modified example of the expansion joint of FIG. 5.
12 to 14 are schematic diagrams illustrating a manufacturing method according to a fourth modified example of the expansion joint of FIG. 5.

For a detailed description of the present invention, which will be described later, reference is made to the accompanying drawings that illustrate specific embodiments in which the present invention may be practiced. These embodiments are described in detail enough to enable those skilled in the art to practice the present invention. It should be understood that the various embodiments of the present invention are different, but need not be mutually exclusive. For example, specific shapes, structures, and characteristics described herein may be implemented in other embodiments without departing from the spirit and scope of the invention in relation to one embodiment. In addition, it should be understood that the location or placement of individual components within each disclosed embodiment can be changed without departing from the spirit and scope of the invention. Therefore, the following detailed description is not intended to be taken in a limiting sense, and the scope of the present invention, if appropriately described, is limited only by the appended claims, along with all ranges equivalent to those claimed. In the drawings, similar reference numerals refer to the same or similar functions across various aspects, and length, area, thickness, and the like may be exaggerated for convenience.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings in order to enable those skilled in the art to easily implement the present invention.

1 to 5, and 7 are schematic diagrams illustrating a method of manufacturing a stretchable joint according to the present invention. Here, FIGS. 3 to 5 illustrate a method of manufacturing a stretchable joint tube by enlarging the area'A' of FIG. 2.

1 to 5, and 7, the manufacturing method of the expansion joint 110 according to the present invention includes, first of all, preparing a circular corrugated pipe 30 as shown in FIG. 1. The corrugated pipe 30 is formed into a tubular shape using a stainless plate and has a corrugated portion 10 on one portion and a smooth portion 20 forming a relatively flat shape compared to the corrugated portion 10 on the other portion. The corrugated pipe 30 has a thin thickness of 0.3 mm.

Next, the manufacturing method of the expansion joint 110 includes enclosing a braid 50 on the outer circumferential surface of the corrugated pipe 30 as shown in FIG. 2. Surrounding the braid 50 on the outer circumferential surface of the corrugated pipe 30 is prepared by weaving the braid 50 with a stainless wire in a tubular shape, and the corrugated portion of the corrugated pipe 30 along the longitudinal direction of the corrugated pipe 30 (10) and the smooth portion (20) includes surrounding the braid (50).

The corrugated pipe 30 and the braid 50 have the same length along the longitudinal direction of the corrugated pipe 30. Next, the method of manufacturing the expansion joint 110 includes fitting the positioning tube 102 at one end of the braid 50 as shown in FIG. 2. In FIG. 7, the inner wall 60 of the positioning tube 102 forms a relatively flat shape compared to the corrugated portion 10 of the corrugated pipe 30.

The positioning tube 102 comprises stainless or iron and is thicker than the corrugated tube 30. The fitting of the positioning tube 102 at one end of the braid 50 is provided to the corrugated pipe 30 and the braid 50 through one end of the braid 50 on the smooth portion 20 of the corrugated pipe 30. And fitting the positioning tube 102. Subsequently, the manufacturing method of the expansion joint 110 includes inserting a diffusion tool 120 into the corrugated pipe 30 as shown in FIG. 3.

The diffusion tool 120 is a donut-shaped elastic member 112, a rod 114 is inserted into the opening of the elastic member 112 to act as a horizontally movable piston 114, the rod from one side of the elastic member 112 ( It includes a movement stopper 116 fixed to 114, and a rod guider 118 that is movable relative to the elastic member 112 and the rod 114 on the other side of the elastic member 112. Subsequently, the manufacturing method of the expansion joint 110 includes expanding the corrugated pipe 30 and the braid 50 using the diffusion tool 120.

Using the diffusion tool 120 to expand the corrugated pipe 30 and the braid 50, in FIG. 4, the diffusion tool 120 is used to spread the corrugated pipe 30 inside the corrugated pipe 30 using the diffused tool 120. The elastic member 112 of the 120 is contacted, the rod 114 is moved forward (D1) relative to the rod guider 118 toward the opposite side of the elastic member 112, and the forward movement of the rod 114 During (D1), the elastic member 112 is inflated by inflating the volume of the elastic member 112 toward the inner wall 60 and both sides of the positioning tube 102 between the moving stopper 116 and the rod guider 118. It includes using to push the corrugated pipe 30 and the braid 50.

The length of the elastic member 112 is formed as shown in FIG. 3 or 4 larger than the length of the positioning tube 102 when viewed along the longitudinal direction of the corrugated pipe 30. In FIG. 4, the elastic member 112 pushes the corrugated pipe 30 and the braid 50 along the first arrow direction M1 through the central region 112C to the inner wall 60 of the positioning pipe 102. ) Crimp the corrugated pipe 30 and the braid 50, and push the corrugated pipe 30 and the braid 50 along the first arrow direction M1 through both edges 112P to the amount of the positioning pipe 102 The side portion acts to form a curved portion (C) in the corrugated pipe 30 and the braid 50.

Here, when the elastic member 112 is pushed along the first arrow direction M1, the movement is restricted by the positioning tube 102 in the central region 112C, and is positioned at both edges 112P. It expands larger than the opening diameter of the tube 102. Thus, as shown in FIG. 5, the corrugated pipe 30 and the braid 50, the central region 112C of the elastic member 112 between the observation points (P10, P20) under the positioning tube 102 It is squeezed approximately horizontally along the inner wall 60 of the positioning tube 102 through a cuboid or cube.

In addition, the corrugated pipe 30 and the braid 50, both edges 112P of the elastic member 112 between the observation points (P10 & P11, and P20 & P21) next to both sides of the positioning tube 102 Opened through the bulging trumpet shape of the, and opened ahead due to the deformation resistance phenomenon of the corrugated pipe 30 and the braid 50 between the observation points P11 & P12, and P21 & P22 on the far side of the positioning tube 102. The shape is gradually closed from the vertices P11 and P21.

Through this, the corrugated pipe 30 and the braid 50 form an'M' or'W' shaped bend around the positioning pipe 102 through the elastic member 112. That is, the corrugated pipe 30 and the braid 50, after the expansion of the diffusion tool 120, spread toward both sides of the positioning tube 102 to the curved portion (C) on both sides of the positioning tube 102 Have In addition, the corrugated pipe 30 and the braid 50 have an uneven shape due to the inner sidewall 60 of the positioning pipe 102 below the positioning pipe 102.

Thereafter, the method of manufacturing the telescopic joint 110 includes separating the diffusion tool 120 from the inside of the corrugated pipe 30. Separating the diffusion tool 120 from the inside of the corrugated pipe 30 moves the rod 114 backward relative to the rod guider 118 from the opposite side of the elastic member 112 toward the elastic member 112. (D2), during the retraction movement (D2) of the rod 114, the elastic member toward the center of the corrugated pipe (30) along the second arrow direction (M2) between the movement stopper 116 and the rod guider 118 Reducing the volume of (112) to space the elastic member (112) from the corrugated pipe (30) and using the rod (114) of the diffuser tool (120) to remove the diffuser (120) from the interior of the corrugated pipe (30) Includes.

FIG. 6 is a schematic diagram illustrating a manufacturing method according to a first modification of the expansion joint of FIG. 5, and FIG. 8 is a schematic diagram illustrating a manufacturing method according to a second modification of the expansion joint of FIG. 5.

9 to 11 are schematic diagrams for explaining the manufacturing method according to the third modification of the expansion joint of FIG. 5. Here, FIGS. 10 and 11 are cross-sectional views taken along the cutting line I-I'of FIG. 9.

12 to 14 are schematic diagrams illustrating a manufacturing method according to a fourth modified example of the expansion joint of FIG. 5. Here, FIGS. 13 and 14 are cross-sectional views taken along cutting lines II-II' and III-III' of FIG. 10.

Referring to FIG. 6, the manufacturing method according to the first modification of the expansion joint of the present invention is similar to the production method of the expansion joint 110 of FIGS. 1 to 5, however, the expansion joint of the present invention The manufacturing method according to the first modified example of the method further includes forming an iron spring (not shown in the drawing) or a plurality of rubber O-rings 40 between the corrugated pipe 30 and the braid 50.

The iron spring or the plurality of rubber O-rings 40 is fitted to the smooth portion 20 of the corrugated pipe 30. The corrugated pipe 30 and the braid 50, through the insertion of the diffusion tool 120 inside the corrugated pipe 30 and the expansion of the corrugated pipe 30 by the diffusion tool 120, the corrugated pipe 30 and the braid ( 50) between the springs or a plurality of rubber O-rings (40) to bend to have a large frictional force under the positioning tube (102).

Referring to FIG. 8, the manufacturing method according to the second modification of the expansion joint of the present invention is similar to the production method of the expansion joint 110 of FIGS. 1 to 5. However, in the manufacturing method according to the second modified example of the expansion joint of the present invention, the inner wall 79 of the positioning tube 104 has an annular locking jaw 73 at both inlets of the positioning tube 104 And between the locking jaws 73 to form a relatively flat shape compared to the wrinkle portion 10 of the corrugated pipe (30).

The corrugated pipe 30 and the braid 50, after expansion of the diffusion tool 120, It has an uneven shape under the positioning tube 104. In more detail, the corrugated pipe 30 and the braid 50 are positioned through the expansion of the corrugated pipe 30 by the insertion of the diffusion tool 120 and the corrugated pipe 30 inside the corrugated pipe 30. There is a step between the central region 76 and both edges 73 of the inner wall 79 along the inner wall 79 of the crystal tube 104.

The step difference between the corrugated pipe 30 and the braid 50 makes it difficult to separate the corrugated pipe 30 and the braid 50 from the positioning pipe 104.

9 to 11, the manufacturing method according to the third modified example of the expansion joint of the present invention is similar to the production method of the expansion joint 110 of FIGS. 1 to 5. However, in the manufacturing method according to the third modification of the expansion joint of the present invention, the inner wall 83 of the positioning tube 106 includes a plurality of recesses 86 or iron parts 89. Have

The corrugated pipe 30 and the braid 50, After expansion of the diffusion tool 120, It has an uneven shape under the positioning tube 106. In more detail, the corrugated pipe 30 and the braid 50 are positioned through the expansion of the corrugated pipe 30 by the insertion of the diffusion tool 120 and the corrugated pipe 30 inside the corrugated pipe 30. It is in close contact with the inner wall 83 of the crystal tube 106 and has protrusion shapes corresponding to the plurality of recesses 86 or groove shapes respectively corresponding to the plurality of iron portions 89.

The projection shapes or groove shapes of the corrugated pipe 30 and the braid 50 increase the frictional force between the corrugated pipe 30 and the braid 50 and from the positioning pipe 106 to the corrugated pipe 30 and the braid 50 It makes separation difficult.

12 to 14, the manufacturing method according to the fourth modification of the expansion joint of the present invention is similar to the production method of the expansion joint 110 of FIGS. 1 to 5. However, in the manufacturing method according to the fourth modification of the expansion joint of the present invention, the inner wall 93 of the positioning tube 109 has a plurality of firsts having a first triangular bevel 96A toward one direction. It includes a tooth 96 and a plurality of second teeth 99 having a second triangular inclined plane 99A toward the other direction.

The corrugated pipe 30 and the braid 50 have an uneven shape under the positioning tube 108 after expansion of the diffusion tool 120. In more detail, the corrugated pipe 30 and the braid 50 are positioned through the expansion of the corrugated pipe 30 by the insertion of the diffusion tool 120 and the corrugated pipe 30 inside the corrugated pipe 30. It is in close contact with the inner wall 93 of the crystal tube 108 and has locking groove shapes respectively corresponding to the plurality of first teeth 96 and the plurality of second teeth 99.

The engaging groove shapes of the corrugated pipe 30 and the braid 50 increase the friction between the corrugated pipe 30 and the braid 50 and separate the corrugated pipe 30 and the braid 50 from the positioning pipe 108. It makes it difficult. On the other hand, the manufacturing method of the expansion joint according to the first modification of the present invention in FIG. 6, one of the second to fourth modification of the present invention in FIGS. 8, 9 to 11, and 12 to 14 It may be selected and applied.

30; Corrugated tube, 50; Braid
102; Positioning tube, C; bend
P10, P11, P12, P20, P21, P22; Observation point

Claims (15)

Prepare a circular corrugated pipe,
Surrounding the braid (braid) on the outer peripheral surface of the corrugated pipe,
A positioning tube is fitted at one end of the braid,
A diffusion tool is inserted into the corrugated pipe,
Using the diffusion tool to expand the corrugated tube and the braid,
And separating the diffusion tool from the inside of the corrugated pipe,
The corrugated pipe and the braid, after expansion of the diffusion tool, are in close contact with the inner side wall of the positioning pipe, and have curved portions on both sides of the positioning pipe, and have an uneven or uneven shape below the positioning pipe. ,
The corrugated pipe is formed into a tubular shape using a stainless plate and has a pleated portion on one portion and a smooth portion forming a relatively flat shape compared to the pleated portion on the other portion,
Surrounding the braid on the outer peripheral surface of the corrugated pipe,
Weave the braid (braid) with a stainless wire to prepare in a tubular shape,
And enclosing the corrugated portion and the smooth portion of the corrugated pipe along the longitudinal direction of the corrugated pipe with the braid,
The corrugated pipe and the braid have the same length along the longitudinal direction of the corrugated pipe,
Inserting the positioning tube at the one end of the braid,
And fitting the positioning tube to the corrugated pipe and the braid through the one end of the braid on the smooth portion of the corrugated pipe,
The diffusion tool is a donut-shaped elastic member, a rod inserted into an opening of the elastic member and serving as a horizontally movable piston, a moving stopper fixed to the rod on one side of the elastic member, and the other side of the elastic member In comprises a rod guider that is movable relative to the rod,
Using the diffusion tool to expand the corrugated tube and the braid,
The elastic member of the diffusing tool is brought into contact with the corrugated pipe inside the corrugated pipe using the diffusion tool,
Moving the rod forward relative to the rod guider toward the opposite side of the elastic member,
During the forward movement of the rod, a volume of the elastic member is simultaneously inflated between the moving stopper and the rod guider toward the inner wall and both sides of the positioning tube to push the corrugated pipe and the braid using the elastic member. Including
The length of the elastic member is formed larger than the length of the positioning tube when viewed along the longitudinal direction of the corrugated pipe,
The elastic member,
Pushing the corrugated pipe and the braid through a central region to squeeze the corrugated pipe and the braid on the inner wall of the positioning pipe,
A method of manufacturing a stretchable joint tube that acts to push the corrugated pipe and the braid through both edges to form the curved portion in the corrugated pipe and the braid in the same shape on both sides of the positioning pipe.
delete delete According to claim 1,
Further comprising forming an iron spring or a plurality of rubber O-rings between the corrugated pipe and the braid,
The iron spring or the plurality of rubber O-rings are a method of manufacturing a telescopic joint that is fitted to the smooth portion of the corrugated pipe.
According to claim 1,
The inner wall of the positioning tube, a method of manufacturing a stretchable joint tube forming a relatively flat shape compared to the wrinkled portion of the corrugated pipe.
According to claim 1,
The inner wall of the positioning tube, a method for manufacturing a stretchable joint tube forming a relatively flat shape compared to the wrinkled portion of the corrugated pipe between the annular engaging jaw and the engaging jaws at both inlets of the positioning tube.
According to claim 1,
The inner wall of the said positioning tube, The manufacturing method of the expansion joint tube which has a some recessed part or a convex part.
According to claim 1,
The inner wall of the positioning tube, a first joint having a first triangular bevel in one direction, and a plurality of second serrations having a second triangular inclination in the other direction Way.
delete delete delete delete delete According to claim 1,
Separating the diffusion tool from the inside of the corrugated pipe,
The rod is retracted relative to the rod guider from the opposite side of the elastic member toward the elastic member,
During the retraction movement of the rod, the elastic member is spaced apart from the corrugated pipe by reducing the volume of the elastic member toward the center of the corrugated pipe between the movement stopper and the rod guider,
And removing the diffusion tool from the inside of the corrugated pipe using the rod of the diffusion tool.
According to claim 1,
The positioning tube includes a stainless steel or iron, and a method of manufacturing a stretchable joint tube thicker than the corrugated tube.

Images