JP2009083406A - Pipe joining method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a practical pipe joining method for melting and solidifying a bonding face inexpensively in a short time and dispensing with adhesive and a seal tape. <P>SOLUTION: In this pipe joining method, either of first and second pipes 1, 2 is formed by a thermoplastic material, pigment 3 being absorbed in laser beams 4 is applied on an outer peripheral face of one end of the first pipe, the one end of the first pipe and one end of the second pipe are mutually fitted so that an inner peripheral face of the one end of the second pipe is abutted on the outer peripheral face of the one end of the first pipe, and laser beams are applied on the whole periphery of a fitting part from an outer side of the second pipe to thermally fusion-bond a face where the first and second pipes are mutually abutted and join them. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a pipe joining method that joins two pipes, and more particularly to a joining method in which pipes are thermally fused and joined by laser light emitted from a light irradiation means.

  Conventionally, in order to join pipes, there is a method of joining fitting parts with an adhesive using a jig having an inner diameter that matches the outer shape of the pipes to be joined, but a jig that ensures fitting accuracy is required. Further, since an adhesive is used, man-hours such as time required for fixing and management are required, and sufficient adhesive strength cannot be ensured.

  Also, using a jig with an inner diameter that matches the outer diameter of the pipe to be joined, the screws formed on the jig and both pipes are screwed together, and the fluid flowing in the pipe is further removed from this screwed portion. The sealing tape is used to prevent leakage, but it takes time and labor for screw processing, and the sealing tape is also necessary.

In addition, a special jig that has an inner diameter that matches the outer shape of the pipe in a state where the thermoplastic pipes are in contact with each other and has a built-in heating wire inside is fitted, and a voltage is applied to the fitting portion. In other words, the pipe is melted by flowing electricity and heating the heating heating wire to join the pipes (see, for example, Patent Document 1).
JP-A-11-190487

  However, in the above case, there is a problem that it is necessary to attach jigs to the joints between the pipes, which is costly. Furthermore, since it takes 1 hour or more for the heating wire of the jig to be heated and welded, voltage must be continuously applied during that time, resulting in problems such as longer working time and higher power consumption. .

  The present invention has been made to solve the conventional technical problems, and an object of the present invention is to provide a pipe joining method capable of joining pipes at low cost and in a short time.

  For this reason, the first invention is a joining method for joining the first pipe and the second pipe made of a material that is transmissive to the laser light emitted from the light irradiating means. Either one of the first pipe and the second pipe is made of a thermoplastic material, and a laser light absorbing material is applied to the outer peripheral surface of one end of the first pipe, and one end of the first pipe is formed. The outer peripheral surface of the second pipe is fitted so as to abut on the inner peripheral surface of one end of the second pipe, and the laser is applied over the entire circumference of at least one place from the outside of the second pipe in the fitting portion. It is characterized in that light is irradiated to cause the laser light absorbing material to absorb laser light and generate heat, and the first and second pipes are thermally fused and joined.

According to a second aspect of the present invention, when the first and second pipes have substantially the same diameter, an outer peripheral surface on one end side of the first pipe is cut out, and an inner periphery on one end side of the second pipe The surface is cut off, a laser light absorbing material is applied to the outer peripheral surface on one end side of the first pipe, and the cut portion on the outer peripheral surface on one end side of the first pipe is set on the inner end side of the second pipe. It fits so that it may contact | abut to the cut part of a surrounding surface.

  The third invention is characterized in that an outer diameter on one end side of the first pipe is formed substantially the same as an inner diameter on one end side of the second pipe.

  According to a fourth aspect of the present invention, an outer diameter on one end side of the first pipe is set to be equal to or larger than an inner diameter on one end side of the second pipe, and a laser light absorbing material is applied to the outer peripheral surface on one end side of the first pipe. Then, one end of the second pipe is heated and expanded to expand the inner diameter to be equal to or larger than the outer diameter of the one end of the first pipe. The pipe is fitted into one end side of the pipe, and the fitting portion is cooled to generate pressure between the fitting surfaces of both pipes.

  According to a fifth aspect of the present invention, a protrusion protruding in the radial direction of the outer peripheral surface on the one end side of the first pipe is formed, and a laser light absorbing material is applied to the outer peripheral surface on the one end side of the first pipe, Forming a recess corresponding to the protruding portion projecting in the radial direction of the outer peripheral surface on the one end side of the first pipe in the radial direction of the inner peripheral surface on the one end side of the second pipe; One end side of the second pipe is fitted into one end side of the second pipe, and the projection and the recess are engaged to hold the first pipe in the second pipe. It is characterized by that.

  In the fifth invention, it is needless to say that a part of the fitting portion of the first and second pipes may be screwed together.

    According to a sixth invention, in the invention relating to any one of the first to fifth pipe joining methods, in the invention relating to the joining method of the first invention, the material that absorbs laser light is carbon. It is the main raw material.

    A seventh aspect of the invention relates to any one of the first to fifth pipe joining methods, wherein the laser oscillates between 400 nm and 1150 nm. It is characterized by having a wavelength.

  According to an eighth aspect of the invention related to any one of the first to seventh pipe joining methods, the first pipe is a material that absorbs laser light. In the case of the eighth invention according to the present invention, it is convenient that the step of applying the laser light absorbing material to the outer peripheral surface on one end side of the first pipe can be omitted.

  When joining pipes in piping work etc., a practical pipe joining method that can melt and solidify the joining surface in a short time without the need for special jigs and joint members and does not require adhesives or sealing tape Can be provided.

  Hereinafter, embodiments of the present invention will be described. 1st Embodiment of the joining method of a pipe is described based on FIG. First, reference numeral 1 denotes a first pipe such as a gas pipe or a water and sewage system, which is formed of a thermoplastic resin, specifically, a polyolefin-based synthetic resin, for example, a polyethylene synthetic resin in this embodiment.

  The first pipe 1 is made of a thermoplastic synthetic resin material such as an acrylic resin or a polyethylene resin. Generally, a medium density polyethylene synthetic resin material is used for a gas pipe, and a high density is used for a water supply or sewerage system. Polyethylene synthetic resin material is used.

  The outer diameter of the first pipe 1 is the same as the inner diameter of the second pipe 2, and a dye (laser light absorbing material) that absorbs laser light on the outer peripheral surface on one end side of the first pipe 1. ) After applying 3 and drying, insert one end of the first pipe 1 coated with the laser light absorbing material (laser light absorbing material) 3 into the one end of the second pipe 2 Then, the outer peripheral cylindrical surface coated with a dye (laser light absorbing material) 3 that absorbs the laser light of the first pipe 1 is used as the inner peripheral cylindrical surface on one end side of the second pipe 2. The contact state is assumed. Then, the first pipe 1 and the second pipe 2 are irradiated with laser light 4 from the outside of the second pipe 2 to the entire circumference of at least one place of the fitting section. The dye (laser light absorbing material) 3 existing on the abutting cylindrical surface absorbs the laser beam 4 and generates heat, thereby melting the abutting cylindrical surfaces of the first pipe 1 and the second pipe 2 together. The first pipe 1 and the second pipe 2 are joined. The laser beam 4 is radiated so as to be substantially uniform over the entire circumference of the fitting portion.

  The laser beam 4 may be a semiconductor laser, a fiber laser, a YAG laser or the like as an oscillation source.

  Next, a second embodiment will be described with reference to FIGS. First, the same or similar numbers as those in the first embodiment will be described below assuming that they have the same or similar functions. In the second embodiment, when the first pipe 1 and the second pipe 2 to be joined have substantially the same diameter, an outer peripheral surface on one end side of the first pipe 1 is cut off and an insertion step is provided. Forming an outer peripheral surface on one end side of the second pipe 2 to form a receiving port portion, an outer surface of an insertion stepped portion on one end side of the first pipe 1, and the second The first pipe is coated with a dye (laser light absorbing material) 3 having absorptivity to laser light on one or both of the inner surface of the receiving portion at one end of the pipe 2 and dried. One insertion stepped portion is fitted to the receiving portion of the second pipe 2. And in this fitting part, from the outer side of the said 2nd pipe 2, the laser beam 4 is irradiated over the perimeter of at least one place of a fitting part, The said 1st pipe 1 and the said 2nd pipe 2 The pigment (laser light absorbing material) 3 present on the fitting contact surface of the first and second pipes 2 absorbs and generates heat, thereby bringing the first and second pipes 1 and 2 together. The pipe 1 and the pipe 2 are joined by melting. It is even better if the laser light 4 is irradiated so as to be uniformly distributed over the entire circumference of the fitting portion.

  Next, a third embodiment will be described with reference to FIGS. First, the same or similar numbers as those in the first embodiment will be described below assuming that they have the same or similar functions. In the third embodiment, the inner diameter of the second pipe 2 is smaller than the outer diameter of the first pipe 1 to be joined, and the second pipe 2 is heated and expanded to thereby expand the first pipe 1. When the inner diameter of the second pipe 2 is substantially equal to or larger than the outer diameter of the pipe 1, one end side of the second pipe 2 is heated and expanded, and the second pipe 2 and the laser beam 4 are expanded. On the other hand, one end of the first pipe 1 that has been coated with an absorbent dye (laser light absorbing material) 3 and dried is fitted. When the fitting portion of the pipe is cooled in the fitted state, pressure is applied to the fitting contact surfaces of the pipes of the fitting portion due to the contraction of the second pipe 2, thereby the laser beam. No gap or gap when irradiating 4. Then, laser light 4 is irradiated from the outside of the second pipe 2 over the entire circumference of at least one of the fitting portions of the two pipes, so that the first pipe 1 and the second pipe 2 The dye (laser light absorbing material) 3 present on the contact surface absorbs the laser beam 4 and generates heat, thereby melting the contact surfaces of the pipe 1 and the pipe 2 together to join the pipe 1 and the pipe 2 together. It is better to devise the irradiation of the laser beam 4 so that the irradiation is performed uniformly over the entire circumference of the fitting portion.

Next, a fourth embodiment will be described with reference to FIG. First, the same or similar numbers as those in the first embodiment will be described below assuming that they have the same or similar functions. The fourth embodiment forms a protruding portion protruding in the radial direction of the outer peripheral surface on one end side of the first pipe 1,
Applying a dye (laser light absorbing material) 3 that absorbs laser light 4 to the outer peripheral surface on one end side of the first pipe, in the radial direction of the inner peripheral surface on one end side of the second pipe, Forming a recessed portion corresponding to the protruding portion projecting in the radial direction of the outer peripheral surface of one end side of the first pipe, and fitting one end side of the first pipe into one end side of the second pipe; The protrusions and the recesses are engaged with each other so that the first pipe is held in the second pipe. Then, laser light 4 is irradiated from the outside of the second pipe 2 over the entire circumference of at least one of the fitting portions, and the contact surface between the first pipe 1 and the second pipe 2 is irradiated. The existing dye (laser light absorbing material) 3 absorbs the laser light 4 and generates heat, thereby melting the contact surfaces of the first pipe 1 and the second pipe 2 together with the first pipe 1. The second pipe 2 is joined. It is better to devise the irradiation of the laser beam 4 so that the irradiation is performed uniformly over the entire circumference of the fitting portion.

  Further, in the first to fourth embodiments, when the first pipe 1 is made of plastic, before the pipe is manufactured, a material that absorbs the laser light 4 mainly made of carbon, such as carbon black, in advance. Is prepared as a raw material for manufacturing a laser welded pipe, and a pipe is manufactured using the raw material for manufacturing a laser welded pipe, thereby using a pipe containing a material that absorbs laser light 4 You can also. This eliminates the need for the application and drying operations of the dyes described in the first to fourth embodiments, and enables a quicker joining operation. The pipe containing a material that absorbs laser light is required to have a strength required for use.

  Hereinafter, the present invention will be disclosed in more detail by way of examples. However, the examples and the like are intended to explain the essence of the present invention, and the scope of the present invention should not be construed as being limited thereto.

(Preprocessing)
The pipe 1 (pipe for water supply, material: high-density polyethylene, color: blue, dimension φ60 mm, thickness 6 mm) was subjected to removal processing over a length of 70 mm so that the outer diameter on one end side became 54 mm. Further, the pipe 2 (pipe for water supply, material: high-density polyethylene, color: blue, dimension φ60 mm, thickness 6 mm) was subjected to removal processing over a length of 70 mm so that the inner diameter on one end side became 54 mm. An application material (laser light absorbing material manufactured by Orient Chemical Co., Ltd.) that absorbs laser light was applied to the removed portion (φ54 mm, length 70 mm) of the pipe 1 and dried. The coating material that absorbs laser light uses carbon as a main raw material. The pipe 2 is coated with an absorbent coating material and dried, and the pipe 1 is inserted and fitted into one end, and the pipe 1 is coated with an absorbent coating material for the laser beam and the pipe. The test piece 1 was obtained as the state which contacted the inner peripheral surface of one end side of No.2.

(Laser welding)
While rotating the test piece 1, the fitting contact portion of the test piece 1 was irradiated with a laser, thermally fused, and joined. The laser used for bonding had an oscillation wavelength of 1100 nm and an output of 25 W. Moreover, since the weight of the used laser beam machine is 10 kg or less and is a portable size, it can be joined at the place where the water supply pipe is constructed.
(Welding results)
A pressure resistance test was performed in which a hydrostatic pressure of 1.75 MPa was applied to the inside of the test piece 1 welded with a laser for 18 hours. The result was satisfactory with no water leakage, deformation, breakage or other abnormalities at the joint. It was. Moreover, when the tensile test of the test piece 1 joined with the laser was performed, the tensile strength was 12.8 MPa, and the fractured part was also a base material. Therefore, good results were obtained with respect to the mechanical strength of the joined part. .

(Preprocessing)
Prepare pipe 3 (household water pipe, material: high-density polyethylene, color: white translucent, dimensions: outer diameter φ30mm, thickness 2mm). Absorbent coating material (made by Orient Chemical Co., Ltd.) was applied and dried. The pipe 4 (household water pipe, material: high-density polyethylene, color: white translucent, outer diameter φ34 mm, thickness 2 mm) is coated with a coating material that absorbs laser light and dried. 3 is inserted and fitted into one end side of the pipe 3 so that the outer peripheral surface of the pipe 3 coated with a coating material that absorbs laser light and the inner peripheral surface of the one end side of the pipe 4 are brought into contact with each other. 2 was obtained.

(Laser welding)
While rotating the test piece 2, the fitting contact portion of the test piece 2 was irradiated with a laser beam, thermally fused, and joined. The laser beam used for bonding had an oscillation wavelength of 1100 nm and an output of 25 W. Moreover, since the weight of the used laser beam machine is 10 kg or less and is a portable size, it can be joined at a place where a household water pipe is constructed.
(Welding results)
A pressure resistance test was performed in which a hydrostatic pressure of 2.2 MPa was applied to the inside of the test piece 2 joined with a laser for 1 minute. The result was satisfactory with no water leakage, deformation, breakage or other abnormalities at the joint. It was.

(Preprocessing)
The pipe 5 (gas piping, material: polyethylene, color: yellow, dimension φ60 mm, thickness 6 mm) was removed and processed over a length of 70 mm so that the outer diameter was 54 mm. Further, the pipe 6 (gas piping, material: high-density polyethylene, color: yellow, dimension φ60 mm, thickness 6 mm) was subjected to removal processing over a length of 70 mm so that the inner diameter became 54 mm. A removing material (φ54 mm, length 70 mm) of the pipe 5 was coated with a coating material (absorbed by Orient Chemical Co., Ltd.) that absorbs laser light and dried. The pipe 6 is coated with an absorbent coating material and dried, and the pipe 5 is inserted and fitted with one end side, and the pipe 5 is coated with an absorbent coating material for the laser beam and the pipe. The test piece 3 was obtained as the state which contacted the inner peripheral surface of one end side of 6.

(Laser welding)
While rotating the test piece 3, the fitting contact portion of the test piece 3 was irradiated with a laser beam and thermally fused and joined. The laser beam used for bonding had an oscillation wavelength of 1100 nm and an output of 25 W. Moreover, since the weight of the used laser beam machine is 10 kg or less and is a portable size, it can be joined at the place where the gas pipe is constructed.
(Welding results)
A pressure resistance test was performed in which a hydrostatic pressure of 1.75 MPa was applied to the inside of the test piece 3 joined by a laser for 1 minute. The result was satisfactory with no water leakage, deformation, breakage or other abnormalities in the welded part. It was.

  Although the embodiments of the present invention have been described above, various alternatives, modifications or variations, and pipe shapes can be selected by those skilled in the art based on the above description, and the present invention is described above without departing from the spirit of the present invention. Various alternatives, modifications or variations, and selection of pipe shapes. The shape of the pipe includes, for example, a T-shape, L-shape, ten-hour shape or header called cheese.

It is a vertical front view of both pipes for demonstrating 1st Embodiment of the joining method of a pipe. It is a vertical front view of both pipes for demonstrating 2nd Embodiment of the joining method of a pipe. It is a vertical front view of both pipes for demonstrating 2nd Embodiment of the joining method of a pipe. It is a vertical front view of both pipes for demonstrating 3rd Embodiment of the joining method of a pipe. It is a vertical front view of both pipes for demonstrating 3rd Embodiment of the joining method of a pipe. It is a vertical front view of both pipes for demonstrating 4th Embodiment of the joining method of a pipe.

Explanation of symbols

1 1st pipe 2 2nd pipe 3 Dye (laser light absorbing material)
4 Laser light

Claims (8)

  A joining method for joining a first pipe and a second pipe made of a material that is transmissive to laser light emitted from a light irradiating means, wherein at least one of the first and second pipes Any one of these is made of a thermoplastic material, a laser light absorbing material is applied to the outer peripheral surface on one end side of the first pipe, and the outer peripheral surface on one end side of the first pipe is applied to the second pipe. The laser beam is irradiated so as to be brought into contact with the inner peripheral surface on one end side of the pipe, and the laser beam is irradiated from the outside of the second pipe to the entire circumference of at least one place in the fitting portion. A method of joining pipes, wherein the absorbing material absorbs laser light and generates heat, and the first and second pipes are thermally fused and joined. When the first and second pipes have substantially the same diameter, the outer peripheral surface on one end side of the first pipe is cut off, the inner peripheral surface on one end side of the second pipe is cut off, A laser light absorbing material is applied to the outer peripheral surface on one end side of the first pipe, and the cut portion on the outer peripheral surface on one end side of the first pipe is used as the cut portion on the inner peripheral surface on one end side of the second pipe. The pipe joining method according to claim 1, wherein the pipes are fitted so as to contact each other. The pipe joining method according to claim 1, wherein an outer diameter on one end side of the first pipe is formed substantially the same as an inner diameter on one end side of the second pipe.   An outer diameter on one end side of the first pipe is set to be equal to or larger than an inner diameter on one end side of the second pipe, a laser light absorbing material is applied to an outer peripheral surface on one end side of the first pipe, and the second pipe The one end side of the first pipe is set in the one end side of the second pipe in a state where the inner diameter is equal to or larger than the outer diameter of the one end side of the first pipe by heating and expanding one end side of the second pipe. The pipe joining method according to claim 1, wherein pressure is generated between the fitting surfaces of both pipes by cooling the fitting portion and cooling the fitting portion.   A protrusion projecting in the radial direction of the outer peripheral surface on one end side of the first pipe is formed, and a laser light absorbing material is applied to the outer peripheral surface on one end side of the first pipe, and the second pipe A concave portion corresponding to the protrusion protruding in the radial direction of the outer peripheral surface of the one end side of the first pipe is formed in the radial direction of the inner peripheral surface of the one end side, and the one end side of the first pipe is The first pipe is held in the second pipe by being fitted into one end side of the second pipe, the projection and the recess being engaged with each other. Item 2. A method for joining pipes according to Item 1.   The pipe joining method according to any one of claims 1 to 5, wherein the laser light absorbing material is carbon as a main raw material.   The pipe joining method according to any one of claims 1 to 5, wherein the laser beam has any one oscillation wavelength between 400 nm and 1150 nm.   The pipe joining method according to claim 1, wherein the first pipe absorbs laser light.