JP4159311B2 - Pipe with receptacle made of olefin resin - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to the structure of a pipe with an olefin-based resin receiving port in which a pipe end is expanded by secondary processing to form a connecting receiving port. More specifically, the present invention relates to a pipe with a receiving port suitable for fusion of a pipe having a large diameter (outer diameter of 75 mm or more).
[0002]
[Prior art]
Conventionally, various connection methods for olefin-based resin pipes have been proposed. One of the connection methods is socket fusion. In the socket fusion, the outer peripheral surface of the insertion port of the pipe to be inserted and the inner peripheral surface of the insertion port of the socket fusion joint to be inserted are heated by a dedicated heater, and then the insertion port of the pipe is inserted into the receptacle of the socket fusion joint. It was what was fused. The socket fusion joint includes an elbow and a cheese shape in addition to the socket 15 shown in FIG. 5, and is manufactured by injection molding. As shown in FIGS. 5 to 7, the procedure for fusing the socket and the pipe of the socket fusion joint is to connect the inner peripheral surface of the receiving port 16 on one side of the socket 15 and the outer peripheral surface of the insertion port 18 of the pipe 17. Then, heating is performed by a dedicated heater 19 for a certain period of time (the state shown in FIG. 5), and then the pipe 17 and the socket 15 are pulled out from the heater 19, and the insertion port 18 of the pipe 17 is inserted into the receiving port 16 of the socket 15. (State of FIG. 6). The other side was also fused in the same way (state shown in FIG. 7).
[0003]
[Problems to be solved by the invention]
However, the above-described injection-molded socket fusion joint has the following problems when described with reference to FIG.
[0004]
An inner peripheral bead 20 and an outer peripheral bead 21 are generated at locations connected by socket fusion. The socket 15 is provided with a gap for accommodating the inner peripheral bead 20 between the insertion end faces 22 and 23 of the pipe fused to the socket 15 so that the inner peripheral bead 20 does not go out into the pipe line. Yes. Due to the gap and the inner peripheral bead 20, the fused portion at the back of the receiving port is uneven, which causes a dead space.
Furthermore, in order to connect using the socket fusion joint, at least two fusions are required, and the fusion work takes time and effort.
In addition, since the socket fusion needs to be uniformly fused all around, the better the roundness of the pipe 17 and the receiving port 16 is, the more reliable the fusion is. In particular, the larger the diameter, the flatter the receiving port, and the roundness becomes worse. In the flat state, the variation in the inner diameter size increases, and if it is fused as it is, defective fusion tends to occur. When post-processing is performed on the receptacle to correct the flatness, the manufacturing process is increased and the processing cost is excessive.
[0005]
The present invention has been made in view of the above-mentioned problems of the prior art, and its purpose is to connect a pipe made of olefin-based resin, so that socket fusion with less dead space can be performed. An object of the present invention is to provide a socket-fitted socket-attached pipe made of olefin-based resin, which has a short wearing time, good roundness of the receptacle, and can be connected to a pipe at low cost.
[0006]
[Means for Solving the Problems]
In order to solve the above problems, the configuration of the present invention will be described with reference to FIG. 1. The socket fusion receptacle is formed by secondary processing for expanding the diameter after heat softening the end of the pipe made of olefin resin. In the formed pipe 1 with an opening, the maximum inner diameter d of the opening end 4 of the opening 3 is in the range of 96.0% to 99.8% with respect to the outer diameter D of the straight pipe 2. The first feature is that the inner peripheral surface of the receiving port 3 is a tapered surface 5 and the taper angle θ is in the range of 0.1 ° <θ <1.4 °. The third characteristic is that the wall thickness t of the receiving portion 3 is in the range of 9.5 <D / t <11.5 with respect to the outer diameter D of the straight pipe portion 2. The density is 0.89 to 0.93, the melting point is 145 ° C. to 170 ° C., and the melt flow rate (hereinafter abbreviated as MFR) is 0.1 to 1. That is g / 10 min Polypropylene is to the fourth aspect.
[0007]
The maximum inner diameter d in the present invention is preferably in the range of 96.0% to 99.8% with respect to the outer diameter D of the straight pipe portion 2, and is in the range of 98.0% to 99.4%. Is more preferable. In order to easily insert the insertion port of the pipe into the receiving portion 3, it is necessary to be 96.0% or more of the outer diameter D. Further, in order to obtain an effective amount of beads at the time of socket fusion, it is necessary to be 99.8% or less of the outer diameter D.
[0008]
In a preferred embodiment of the present invention, the taper angle θ of the taper surface 5 provided on the inner peripheral surface of the receiving portion 3 of the pipe with receiving port 1 is in the range of 0.1 ° <θ <1.4 °. Is preferred. In order to generate a sufficient amount of beads when inserting the insertion opening into the receiving portion 3, it is necessary that θ> 0.1 °. Further, in order to suppress the insertion resistance for inserting the insertion opening into the receiving portion 3, it is necessary that θ <1.4 °.
[0009]
In another preferred embodiment of the present invention, the wall thickness t of the receiving port portion 3 is 9.5 <D / t <11.5 with respect to the outer diameter D of the straight pipe portion 2 of the pipe 1 with the receiving port. It is preferably in the range, and more preferably in the range of 10.5 <D / t <11. In order to suppress post-shrinkage after secondary processing, it is necessary that D / t> 9.5. Further, in order to make the strength of the fused portion equal to or higher than that of the pipe, it is necessary that D / t> 11.5.
[0010]
In another preferred embodiment of the present invention, preferred examples of the olefin resin include polyethylene, polypropylene, polybutene, etc. Among them, polypropylene is preferred. The density of the polypropylene is preferably in the range of 0.89 to 0.93, and more preferably in the range of 0.900 to 0.915. In order to obtain a degree of crystallinity so that the strength that can withstand the use of the pipe can be maintained, the density needs to be 0.89 or more. Further, the density needs to be 0.93 or less in order to reduce the content of impurities in polypropylene so that the elution of the pipe is improved. Next, the melting point is preferably in the range of 145 ° C to 170 ° C, and more preferably in the range of 150 ° C to 165 ° C. In order to obtain heat resistance of the pipe, it is necessary that the melting point is 145 ° C. or higher. Further, in order to suppress the manufacturing cost by reducing the superheated melting temperature at the time of pipe extrusion and secondary processing as much as possible, the melting point needs to be 170 ° C. or lower.
[0011]
The MFR of polypropylene is preferably in the range of 0.1 to 1.5 g / 10 minutes, and more preferably in the range of 0.2 to 1.0 g / 10 minutes. In order to secure an appropriate fluidity for the extrusion of the pipe and the molding of the secondary processing, it is necessary that the MFR is in the range of 0.1 to 1.5 g / 10 minutes.
[0012]
As another embodiment, the insertion margin Z of the receiving portion 3 of the pipe with receiving port 1 is preferably within a range of 0.3D to 0.7D with respect to the outer diameter D of the straight pipe portion 2. It is more preferable that it is 35D-0.55D. In order to obtain the strength of the fused part, it is necessary that the insertion margin Z is 0.3D or more. Moreover, in order to suppress the insertion resistance which inserts an insertion port, it is required to be 0.7D or less.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to FIGS. 1 to 4, but it goes without saying that the present invention is not limited to these embodiments.
[0014]
1 is a longitudinal sectional view of a pipe with a receptacle according to the present invention, and FIG. 2 is a longitudinal sectional view showing a state in which a receptacle portion of the pipe with a receptacle and a pipe insertion port are heated by a heater. Fig. 4 is a longitudinal sectional view when the pipe insertion port is fused to the receiving portion of the heat-melted receiving pipe, and Fig. 4 is a longitudinal sectional view of the receiving pipe showing another embodiment of the present invention. is there.
[0015]
In the figure, 1 is a pipe with a receptacle made of polypropylene having a density of 0.902, a melting point of 166 ° C., an MFR of 0.5 g / 10 min, and an outer diameter of 90 mm. The pipe with receptacle 1 is formed of a straight pipe portion 2 and a one-side receptacle portion 3.
The maximum inner diameter of the receiving portion 3 is 89.1 mm and is provided with a size of 99% with respect to the outer diameter D of the straight pipe portion 2. A taper surface 5 is provided that is reduced in diameter toward the portion 2 for a while, and the taper angle θ of the taper surface 5 is provided to be 0.6 °.
The wall thickness t of the receiving portion 3 is 8.2 mm, and is provided so that D / t = 11 with respect to the outer diameter D of the straight pipe portion 2. Since the wall thickness t of the receiving portion 3 expanded by the secondary processing of the pipe is slightly thinner than the thickness of the pipe, the thickness of the pipe before the secondary processing is slightly thicker than the normal pipe in advance. May be used.
The insertion margin Z of the receiving portion 3 is 40.5 mm, and is provided to be 45% of the outer diameter D of the straight pipe portion 2.
[0016]
The embodiment of the present invention has a structure in which the receiving port 3 is formed only at the end portion on one side of the straight tube portion 2, but as another embodiment, as shown in FIG. A structure formed at both ends of the portion 2 may be used.
[0017]
Next, the manufacturing method of this embodiment is demonstrated.
[0018]
The receiving part 3 is inserted into a pipe heating device in which a heater is arranged along the inner peripheral surface so that the pipe end is positioned in the center of the heater so as not to contact the heater, and the pipe end is not contacted The pipe end is heated until it is softened by increasing the temperature of the pipe end to near the melting point of 166 ° C., and the axis of the heat softened pipe is aligned with the core for socket socket receiving molding. It is manufactured by the secondary processing method of the process of expanding the diameter of the pipe end by inserting and removing the pipe end from the core mold after cooling.
In addition, since the receiving part 3 which performed secondary processing deteriorates by oxidation, in order to suppress this, you may use the polypropylene which mix | blended phosphorus antioxidant, and added 500 ppm or more of phosphorus antioxidants Polypropylene is effectively suppressed from oxidative deterioration even when secondary processing is performed.
[0019]
Comparing the roundness of the socket fusion joint formed by injection molding with the pipe with the receptacle manufactured by this secondary processing method, as the diameter of the socket fusion joint receptacle formed by injection molding becomes larger, When the flattened socket fusion joint is fused without being post-processed, the flatness is increased, and the outer peripheral beads are dispersed and are generated around the entire circumference, resulting in poor fusion. On the other hand, the receiving port portion 3 of the pipe with the receiving port manufactured by the secondary processing method of the present invention heats and softens the pipe end portion having a specified roundness, aligns the axis, and is inserted into the core mold. Since the end of the pipe is expanded, flatness can be suppressed and the roundness is good. Therefore, since the outer circumferential bead 13 is generated with a constant size on the entire circumference even when fused, it can be fused uniformly.
[0020]
Next, this embodiment and the method for fusing the pipe insertion will be described with reference to FIG.
[0021]
Reference numeral 6 denotes an insertion hole for the pipe 7 to be fused to the pipe 1 with the opening.
Reference numeral 8 denotes a socket fusion heater. One side of the heater 8 is provided with a convex part 9 for heating the receiving part, and the other side is provided with a concave part 10 for heating the insertion opening 6. The heater is heated to a constant temperature at 210 ° C., and the temperature difference between the convex portion 9 and the concave portion 10 is set to be within 3 ° C.
[0022]
First, the receiving portion 3 is fitted into the convex portion 9 and the insertion port 6 is simultaneously fitted into the concave portion 10 (the state shown in FIG. 2), and after being held at a predetermined pressure for a predetermined time, The insertion opening 6 is inserted into the reception opening 3 by pulling out the reception opening 3 and the insertion opening 6. At this time, excess resin on the outer periphery of the insertion slot 6 is scraped off by the opening end 4, and excess resin on the inner periphery of the receiving port 3 is inserted while being scraped off by the insertion slot end surface 11. The insertion end face 11 is inserted to the receiving back portion 12 to complete the fusion, and the outer peripheral bead 13 and the inner peripheral bead 14 are generated by the surplus resin scraped off (state of FIG. 3).
[0023]
At this time, the outer peripheral bead 13 can determine whether the fused state is good by measuring the height and width. The receptacle back portion 12 is filled with the inner peripheral bead 14, and the amount of unevenness due to fusion of the receptacle back portion 12 is small, and the dead space can be small. On the other hand, in the case of the socket 15 formed by conventional injection molding, the gap for accommodating the beads generated by fusing the pipe from both ends is larger than the receiving end 12 of the receiving pipe 1 of the present invention. Since the amount of unevenness due to fusion is large and the dead space is twice or more that of the present invention, the dead space can be reduced by fusion of the pipe with the opening of the present invention.
[0024]
In addition, in order for the joint for sockets formed by injection molding to fuse two or more receptacles, the socket 15 needs to be fused twice. However, if the pipe with the receptacle of the present invention is used, fusion is performed. Only one half of the wearing point is required, and the time required for fusion work can be greatly reduced. Further, conventionally, a socket is required to connect the pipes, but if the pipe with a receptacle according to the present invention is used, the socket becomes unnecessary and the cost of piping can be reduced.
[0025]
Moreover, although the taper surface 5 is provided in the inside of the receptacle part 3, the shift | offset | difference of the core at the time of a fusion | melting can be corrected with this taper surface 5, and the fusion | melting failure by the shift | offset | difference of a core can be prevented. . In addition, it functions to extrude excess resin on the fusion surface as a bead during fusion.
[0026]
【The invention's effect】
The following effects can be obtained by using the olefin resin-made pipe with a receptacle according to the present invention described above.
(1) Socket fusion with little dead space can be performed.
(2) The fusion work time is shortened to about half that of a socket joint, and a socket is not required for pipe connection, so that the cost of piping can be reduced.
(3) Since the roundness of the receiving port is good and the variation in the inner diameter is small, it can be fused uniformly, and is particularly effective for a pipe with a receiving port having a large diameter.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view of a pipe with a receptacle according to the present invention.
FIG. 2 is a longitudinal sectional view showing a state in which a receiving part of a pipe with a receiving opening and a pipe insertion opening are heated by a heater.
FIG. 3 is a longitudinal sectional view when a pipe insertion port is fused to a receiving portion of a pipe with a receiving port.
FIG. 4 is a longitudinal sectional view of a pipe with an opening showing another embodiment of the present invention.
FIG. 5 is a longitudinal sectional view showing a state in which one side socket receptacle and pipe insertion are heated by a heater by a conventional method.
FIG. 6 is a longitudinal sectional view when a pipe insertion port is fused to a socket receptacle on one side by a conventional method.
FIG. 7 is a longitudinal sectional view when a pipe insertion port is fused to a receiving port on both sides of a socket by a conventional method.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Pipe with receptacle 2 ... Straight pipe part 3 ... Receptacle part 4 ... Open end 5 ... Tapered surface 6 ... Insert 7 ... Pipe 8 ... Heater 9 ... Convex part 10 ... Concave part 11 ... Insert end face 12 ... Receptacle Back part 13 ... outer peripheral bead 14 ... inner peripheral bead 15 ... socket 16 ... receiving port 17 ... pipe 18 ... insertion port 19 ... heater 20 ... inner peripheral bead 21 ... outer peripheral bead 22 ... insertion end surface 23 ... insertion end surface D ... straight Pipe outer diameter d ... Maximum inner diameter Z ... Insertion angle θ ... Taper angle t ... Receptor wall thickness

Claims (4)

A pipe (1) with a socket in which a socket fusion socket is formed by secondary processing for expanding the diameter after heat softening the end of the pipe made of olefin resin, and the opening of the socket (3) A pipe with an inlet made of an olefin-based resin, wherein the maximum inner diameter d of the end (4) is in the range of 96.0% to 99.8% with respect to the outer diameter D of the straight pipe portion (2). The inner peripheral surface of the receiving portion (3) is a tapered surface (5), and the taper angle θ is in a range of 0.1 ° <θ <1.4 °. The pipe with the inlet made of the olefin resin described. The thickness t of the receiving port (3) with respect to the outer diameter D of the straight tube (2) is in the range of 9.5 <D / t <11.5. 2. A pipe with a receptacle made of an olefin resin as described in 2. The olefin resin is a polypropylene having a density of 0.89 to 0.93, a melting point of 145 ° C to 170 ° C, and a melt flow rate of 0.1 to 1.5 g / 10 min. Item 5. A pipe with an olefin-based resin receptacle according to any one of Items 1 to 3.

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