JP3725419B2 - Manufacturing method of plastic pipe connection terminal - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method of manufacturing a connection terminal for a plastic pipe used as a liquid feed pipe, more specifically as a water feed pipe, and more specifically as a deep sea water intake pipe.
[0002]
[Prior art]
Conventionally, a connecting terminal of a plastic pipe used as a water pipe has a structure as shown in FIG. In the figure, 10 is a plastic pipe (specifically, a polyethylene pipe), 12 is an outer diameter tapered metal fitting that is inserted inside the end of the plastic pipe 10, and 14 is pressed against the outside of the end of the plastic pipe 10. 16 is a bolt and nut that tightens the flange of the enlarged metal fitting 12 and the flange of the holding metal fitting 14, 18 is a packing attached to the end face groove of the enlarged metal fitting 12, and 20 is a terminal side metal fitting. Reference numeral 22 denotes a fixed flange fixed to the end of the terminal-side metal fitting 20, 24 denotes a loose flange, and 26 denotes a bolt nut that fastens the loose flange 22 and the flange portion of the diameter-expanded metal fitting 12. Thus, the connection terminal of the conventional plastic water pipe uses a metal member.
[0003]
By the way, in recent years, the demand for deep ocean water has been expanding, but water pipes used for pumping deep ocean water often dislike the mixing of metal ions and rust, and are in contact with water, such as water pipelines and their connecting members. There is an increasing demand for all parts to be made of plastic. This is because deep ocean water has a characteristic of being clean and is often used particularly in the medical and health food fields.
[0004]
Conventionally, a connection terminal as shown in FIG. 5 is used for such a request. That is, a plastic cylinder 30 having the same material (polyethylene), the same diameter and the same thickness as the water-feeding plastic pipe 10 and having an annular projection 28 at one end is manufactured, and a metal flange 32 is provided outside the cylinder 30. In the fitted state, the end of the cylindrical body 30 opposite to the annular protrusion 28 is heat-sealed to the end of the plastic tube 10. 34 is a bead made by heat fusion. The connection ends of the two pipes thus obtained are abutted with the packings 36 sandwiched between the respective annular projections 28, and the flanges 32 are tightened with bolts and nuts 38 to be connected. With such a connection structure, the water transported in the plastic tube 10 does not come into contact with the metal, so that metal ions and rust are not mixed and the water is kept clean.
[0005]
[Problems to be solved by the invention]
The connection terminal as shown in FIG. 5 is based on the premise that both the plastic tube 10 and the plastic cylinder 30 are perfect circles. However, in practice, the plastic tube 10 is often deformed flatly during the process of winding, transporting, and storing after manufacture. When the plastic tube 10 and the plastic cylinder 30 are fusion-bonded, the true A step is likely to occur in the fusion spliced part due to a difference in circularity and a dimensional error. When such a level | step difference arises, there exists a problem that the tensile strength and internal pressure strength of a fusion splicing part fall significantly. Further, since the plastic cylinder 30 with the annular protrusion 28 is manufactured by molding, there is a problem that the mold cost is high and the cost is high.
[0006]
An object of the present invention is to provide a manufacturing method for a plastic Kanse' connection a terminal where such problems were solved as described above.
[0007]
[Means for Solving the Problems]
The method for manufacturing a plastic pipe connection terminal according to the present invention includes inserting an end portion of a plastic pipe into a flange fitting for connecting a plastic pipe and projecting a portion protruding from the front end face of the flange fitting of the plastic pipe to an outer diameter flange fitting. The annular projection is formed by heat molding so as to be larger than the inner diameter of the plastic tube, and the portion of the plastic pipe that protrudes from the front end surface of the flange fitting is deformed inward at the end of the plastic pipe. This is performed in a state where an inner diameter regulating member for regulating the above is inserted and an outer diameter regulating member for regulating the outer diameter of the annular protrusion is attached to the front end surface of the flange fitting .
With such a manufacturing method , there is no step in the connection terminal, and the problem of strength reduction can be solved.
[0008]
Manufacturing method of this, since the end of the plastic tube heat molding to be the annular projection is not required in addition to producing the annular projection with a plastic cylindrical body in a conventional mold as a less costly.
[0009]
Inner size specification system member may be detached after heat molding.
[0010]
The outer diameter regulating member may be removed after thermoforming.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
[0012]
FIG. 1 shows an example of a plastic pipe connection terminal manufactured by the manufacturing method of the present invention. In the figure, reference numeral 10 denotes a thermoplastic pipe for water supply (specifically, a polyethylene pipe), and an end of the plastic pipe 10 is inserted through a flange fitting 40. The flange fitting 40 includes a sleeve portion 42 that fits outside the plastic tube 10 and a flange portion 44 formed on one end side of the sleeve portion 42. Bolt holes 46 are formed in the flange portion 44. The flange fitting 40 is fitted to the plastic tube 10 so that the flange portion 44 is located on the end side of the plastic tube 10. The end of the plastic pipe 10 that protrudes from the front end face of the flange fitting 40 (end face on the flange 44 side) is integrated with the plastic pipe 10 in a seamless manner, and the outer diameter is larger than the inner diameter of the flange fitting 42. A large annular protrusion 48 is formed. The outer diameter of the annular protrusion 48 is preferably set to be equal to or smaller than the diameter of the inscribed circle of the plurality of bolt holes 46 provided in the flange portion 44.
[0013]
One embodiment of the production method of the present invention for producing a plastic pipe connection terminal having the above structure will be described with reference to FIG . First, as shown in FIG. 2 (A), the end of the plastic tube 10 is inserted into the flange metal fitting 40, and the plastic tube 10 and the flange metal fitting 40 are fixed by the clamp 50 with the required length protruding from the front end surface of the flange metal fitting 40. Fix in position. An outer diameter regulating member 52 that regulates the outer diameter of the annular protrusion is attached to the front end surface of the flange metal fitting 40 in advance. A hot plate 56 that moves forward and backward by a hydraulic (or pneumatic) cylinder 54 is disposed at a position facing the end face of the plastic tube 10. The hot plate 56 is heated to a temperature (for example, about 200 ° C.) that can soften and deform the material of the plastic tube 10 by the built-in heater. An inner diameter regulating member 58 that fits inside the plastic tube 10 is attached to the hot plate 56.
[0014]
FIG. 2A shows a state in which the hot plate 56 is slightly advanced from the retracted position and the distal end portion of the inner diameter regulating member 58 is inserted into the plastic tube 10. When the hot plate 56 is moved forward by the cylinder 54, the hot plate 56 hits the end surface of the plastic tube 10, and the plastic tube 10 is heated and softened. Since the plastic tube 10 is restricted from being deformed inward by the inner diameter restricting member 58, the softened plastic flows so as to spread outward.
[0015]
When the hot plate 56 is advanced to the final position, it becomes as shown in FIG. That is, the inside of the outer diameter regulating member 52 is filled with the softened plastic, and the excess plastic protrudes from the gap between the outer diameter regulating member 52 and the hot plate 56. In this state, the heating of the hot plate 56 is stopped and forcedly cooled as necessary to solidify the softened plastic. Thereafter, the connecting plate as shown in FIG. 1 can be obtained by retracting the hot plate 56 and pulling out the inner diameter regulating member 58 and then removing the outer diameter regulating member 52 and removing the protruding portion 60 of the plastic.
[0016]
2A to 2B, the sleeve portion 42 functions to prevent the plastic tube 10 from being thermally deformed. The sleeve portion 42 may be provided as necessary, and the flange fitting 40 may be configured only by the flange portion 44.
[0017]
In the embodiment of FIG. 2, the inner diameter regulating member 58 is attached to the hot plate 56, but the inner diameter regulating member is a cylindrical body separated from the hot plate, and after inserting this into a plastic tube, the hot plate is pressed to form an annular shape. The protrusion may be formed, and the inner diameter regulating member may be crushed and removed after the forming. If it does in this way, since the temperature rise of the internal diameter control member by a hot plate will become small and an internal diameter control member becomes difficult to adhere to a plastic pipe, removal of an internal diameter control member becomes easy.
[0018]
FIG. 3 shows a state in which the connection terminal having the configuration shown in FIG. 1 is formed at the end of the plastics 10 and 10 to be connected, and the plastic tubes 10 and 10 are connected. Reference numeral 36 denotes a packing interposed between the annular protrusions 48 and 48, and reference numeral 38 denotes a bolt and nut for fastening the flange portions 44 and 44 to each other. Although FIG. 3 shows a case where two connection terminals are directly connected, a flanged pipe having an inner surface coated with polyethylene may be interposed between the two connection terminals in order to adjust the length.
[0019]
【The invention's effect】
According to the present invention described above, the portion protruding from the front end surface of the flange bracket of the plastic tube, since the annular projection provided can Rukoto together in the absence of plastic tubes and joints, mechanical plastic tube strength as it holds, it is possible to produce a connection terminal that can be connected in a state of high tensile strength and pressure strength plastic tube. Further, since the annular protrusion is directly formed on the end portion of the plastic tube, it is not necessary to separately manufacture the plastic cylinder with the annular protrusion with a mold as in the conventional case, and the cost of the connection terminal can be reduced.
[Brief description of the drawings]
FIG. 1 is a half-cut side view showing an example of a plastic pipe connection terminal manufactured by the manufacturing method of the present invention.
FIGS. 2A and 2B are cross-sectional views showing an embodiment of a method of manufacturing a plastic pipe connection terminal according to the present invention in the order of steps.
3 is a half-cut side view showing a state in which a plastic tube is connected at the connection terminal of FIG. 1;
FIG. 4 is a half-cut side view showing an example of a conventional plastic pipe connection terminal.
FIG. 5 is a half-incision side view showing another example.
[Explanation of symbols]
10: Plastic pipe
40: Flange bracket
42: Sleeve part
44: Flange
46: Bolt hole
48: Annular projection
50: Clamp
52: Outer diameter regulating member
54: Hydraulic cylinder
56: Hot plate
58: Inner diameter regulating member

Claims (1)

Insert the end of the plastic pipe into the flange fitting for connecting the plastic pipe, and heat-mold the part protruding from the front end face of the flange fitting of the plastic pipe so that the outer diameter is larger than the inner diameter of the flange fitting. And inserting the inner diameter regulating member for regulating the deformation of the plastic tube at the end of the plastic pipe at the end of the plastic pipe flange, A method for manufacturing a plastic pipe connection terminal, comprising: an outer diameter regulating member that regulates an outer diameter of an annular projection being attached to a front end surface of a flange fitting .

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