JPH01199091A - Pipe fitting and its manufacture - Google Patents

Abstract

PURPOSE:To prepare the internal surface flat and smoothness in the same degree as the inner surface of a tubing by furnishing connection holes in a passage, forming grooves and ridges at the outer wall of the passage, making the profile undulated by the grooves and ridges, and by making the inner wall flat and smooth. CONSTITUTION:A pipe fitting A is formed by installing connection holes 6 to which a tubing 100 is inserted, on both sides of a passage 2. Grooves 8 and ridges 9 are formed alternately stretching circumferentially on the outer wall 7 of the passage 2 between the two connection holes 6, and the end of outer wall 7 as cut along the axis is undulated because of the grooves 8 and ridges 9. Further, the inner surface is flat and smooth, and the cylindrical inner wall 15 of the passage 2 over the whole length is fusion welded to the inner surface of the grooves 8 on the outer wall 7. Consequently the inner wall of the tubing is continued by the inner wall of the pipe fitting to allow smooth flow of water, and solids are hard to deposit. Also sufficient strength against earth pressure can be secured.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a synthetic resin pipe joint with a smooth inner surface and a method for manufacturing the pipe joint.

[Conventional technology]

There are straight, T-shaped, and cross-shaped pipe fittings with branching parts, and for those that are buried underground, reinforcing ribs are formed on the outer wall to provide the necessary earth pressure resistance. It may be secured.

FIGS. 6 and 7 show conventional examples of T-shaped pipe joints A, which are used, for example, to connect culvert drain pipes and sewage pipes. In this pipe joint A, branch part 1
The bottom surfaces 4 of one passage 2 and the other passage 3, which are perpendicular to each other, are smoothly continuous without a large step, and on both sides of one passage 2 there are connecting ports 6 into which the tube ends of the tube bodies 100, 100 are inserted. 6 has been extended. The outer wall 7 forming one of the passages 2 is provided with grooves 8 and protrusions 9 alternately formed along the entire length of the branch l along the circumferential direction, and extending along the axis of the outer wall 7. The cut end face shape has a waveform (shape) formed by the grooves 8 and the protrusions 9, and these grooves 8 and the protrusions 9 function as the reinforcing ribs described above. In addition, in the illustrated example of the pipe joint A, grooves and protrusions are alternately formed on both ends of the outer wall 7 as well.

Further, the outer wall IO of the other passage 3 has a threaded portion 1 at its end.
1 is provided, and the configuration is such that, for example, a universal joint (not shown) or the like is connected to this threaded portion 11.

12 is a water hole.

A pipe body 100 shown in FIG. 7 is used as an underdrain drain pipe, a sewage pipe, etc. to be connected to each other using such a pipe joint A, that is, a concave line 111 and a convex line 112 that function as reinforcing ribs are formed alternately. A double-walled tube having a smooth outer wall 110 and an inner wall 120 with a smooth inner surface integrally joined to the inner surface of the grooved strip 111 is sometimes used. Since solid substances such as sand and soil flowing along with water flow smoothly on the smooth inner wall 120, there is an advantage that these solid substances are less likely to accumulate on the inner surface of the inner wall 120.

[Problem to be solved by the invention]

However, when the pipe bodies 100, 100 made of the double-walled pipes described above are connected to each other using the conventional pipe joint A,
As shown in FIG. 7, the inner wall 1 of the tube body 100.
20 and 120 at the pipe joint A. Since the grooves 8 and ridges 9 formed on the outer wall 7 of one passage 2 are interposed, the flow of water may be obstructed by the grooves 8 and ridges 9, or solids may be mixed in the water. tends to accumulate inside the protrusions 9, which reduces the effectiveness of using a double-walled tube with a smooth inner surface as the tube body 100. Similar problems existed with straight or cruciform pipe fittings.

To solve this problem, for example, it is effective to make the protruding strip 9 thick so that its inner surface is flush with the inner surface of the grooved strip 8.
If this is done, extra synthetic resin will be required to fill the internal space of the protruding strip 9 with synthetic resin, which will not only lead to a rise in material costs, but also increase the weight and reduce ease of handling. , it is hard to say that this is a desirable countermeasure.

By the way, the tube fitting A is set in a mold, a tube made of plasticized synthetic resin is extruded from a synthetic resin extrusion die into the - side passage 2, and air is blown into the tube to inflate it. The above grooved line 8
After the tube is heat-sealed to the inner surface of the outer wall 7, an opening is created in the tube by cutting the tube at the intersection point between the tube and the other passage 3, and the inner wall formed by the hardening of the tube becomes the inner wall of the outer wall 7. Because it is provided on the circumference,
This allows water to flow more smoothly than in the conventional example described above, and at the same time makes it difficult for solid matter to accumulate. In addition, with a straight type pipe fitting, there is no need to cut out the tube and create an opening.

However, even if such a manufacturing method is employed, it is impossible to provide the inner surface of the inner wall with the same degree of smoothness as the inner surface of the inner wall 120 of the tube body 100. That is, according to the above manufacturing method, the tube in a plastic state is pushed into the inside of the protrusion 9 by air pressure and expands, so the inner wall becomes wavy, that is, shaped, and it is impossible to eliminate the step.

The present invention has been made in view of the above circumstances, and provides a pipe joint in which a portion connecting the inner walls of a pipe body with a smooth inner surface has a smoothness comparable to that of the inner wall of the pipe body, and a pipe joint of such a pipe joint. The purpose is to provide a manufacturing method.

[Means to solve the problem]

In order to achieve the above object, the pipe joint according to the first invention has the following features:
Connecting ports into which the tube is inserted extend on both sides of the passage, and grooves and protrusions are formed along the circumferential direction on the outer wall of the passage between the two connecting ports, and along the axis of the outer wall. The cut end face has a waveform formed by the grooves and the protrusions, and an inner wall with a smooth inner surface is integrally joined to the inner surface of the grooves.

In the pipe joint according to the second invention, the bottom surfaces of one passage and the other passage that intersect with each other at the branch part are smoothly continuous,
Connecting ports into which the tube is inserted extend on both sides of one passage, and grooves and protrusions are formed along the circumferential direction of the outer wall forming one passage along the entire length of the branch. and the end face shape cut along the axis of this outer wall is a waveform formed by the above-mentioned concave lines and convex lines, the inner surface is smooth, and the inner wall extending over the entire length of one passage is formed by the above-mentioned concave lines. It is integrally joined to the inner surface, and an opening is provided in the inner wall at the intersection of this inner wall and the other passage.

In the method for manufacturing a pipe joint according to the third invention, connecting ports into which the pipe body is inserted extend on both sides of the passage, and grooves and protrusions are formed on the outer wall of the passage between both the connecting ports along the circumferential direction. A synthetic resin extrusion die passes the plastic into the passageway of the synthetic resin molded article, which has stripes formed therein, and whose end face when cut along the axis of the outer wall has a corrugated shape formed by the grooved stripes and the protruding stripes. By extruding a tube made of synthetic resin and inflating it by blowing air while applying tension in the axial direction, the tube is thermally fused to the inner surface of the groove while keeping the inner surface of the tube smooth. It is something to wear.

In the method for manufacturing a pipe joint according to the fourth invention, the bottom surfaces of one passage and the other passage that intersect with each other at the branching part are smoothly continuous, and connection ports into which the pipe body is inserted are extended on both sides of one passage. In addition, a concave line and a convex line are formed along the circumferential direction of the entire length of the branch part in the outer wall forming one of the passages, and the end face shape cut along the axis of this outer wall corresponds to the above-mentioned concave line. A tube made of plasticized synthetic resin is extruded from a synthetic resin extrusion die into one of the channels in the corrugated synthetic resin molded body formed by strips and ridges, and a tensile force is applied to the tube in the axial direction. By blowing air into the tube and inflating it while adding , the tube is thermally fused to the inner surface of the groove while keeping the inner surface of the tube smooth, and then the tube is cut off at the point where the tube intersects with the other passage. This creates an opening in the tube.

[For production]

According to the pipe joints of the first and second inventions, the smooth inner walls provided on the pipe bodies are connected to each other by the smooth inner walls with no steps on the inner surface of the pipe joint.

According to the method for manufacturing a pipe joint of the third and fourth inventions, the tube in a plastic state is not pushed into the inside of the protrusion by air pressure, and the inner surface thereof is kept smooth.

Therefore, when the tube hardens, an inner wall with a smooth inner surface is formed at the inner peripheral portion of the outer wall.

〔Example〕

FIG. 1 is a partial cross-sectional view showing how a pipe joint A according to an embodiment of the first invention is used. In this pipe joint A, the seventh
The difference from the conventional pipe joint A explained in the figure is that it is straight, has a smooth inner surface, and has no branches.
The only difference is that a cylindrical inner wall 15 extending over the entire length of the outer wall 7 is integrally joined to the inner surface of the grooved strip 8 of the outer wall 7 by an appropriate means such as heat fusion. Therefore, the same parts as those in FIG. 7 are given the same reference numerals and detailed explanations will be omitted. Note that the outer wall 7 and the inner wall 15 are molded from the same type of synthetic resin or from compatible synthetic resins.

When pipe bodies 100, 100 made of the above-mentioned double-walled pipes are connected using such a pipe fitting A, the inner walls 120, 120 of each pipe body 100, 100 are connected to the inner surface of the pipe fitting A, as shown in FIG. are continuous by the smooth inner wall 15, water and solids mixed with water flow smoothly over the inner wall 15 of the pipe fitting A, and solids are less likely to accumulate on the inner wall 15.

FIG. 2 is a partial sectional view showing how the pipe joint A according to the second embodiment of the invention is used. In this pipe joint A, the seventh
The difference from the conventional pipe joint A explained in the figure is that the inner surface is smooth, and the cylindrical inner wall 15 extending over the entire length of one passage 2 is bonded to the inner surface of the groove 8 of the outer wall 7 by appropriate means such as heat fusion. The only points are that they are integrally joined together, and that an opening is opened in the inner wall 15 at the intersection of the outer wall 7 and the other passage 3.

Therefore, the same parts as those in FIG. 7 are given the same reference numerals and detailed explanations will be omitted.

When pipe bodies 100, 100 made of the above-mentioned double-walled pipes are connected using such a pipe fitting A, the inner walls 120, 120 of each pipe body 100, 100 are connected to the inner surface of the pipe fitting A, as shown in FIG. are continuous by the smooth inner wall 15, and water and solids mixed with water flow smoothly over the inner wall 15 of the pipe fitting A, making it difficult for solids to accumulate on the inner wall 15. In addition, if a branch pipe is connected to the other passage 3 via, for example, a universal joint (not shown), water and solids may flow from the branch part 1 to the branch pipe, or from the branch pipe to the branch part 1. Flow into.

Next, a method of manufacturing the pipe joint A according to the fourth embodiment of the invention will be described.

In FIG. 3, a synthetic resin molded body B having a predetermined configuration is clamped at a predetermined position in a mold 200, and a tube T made of plasticized synthetic resin is extruded from a synthetic resin molding die 300.
The state where the tube T is inflated by blowing air from the nozzle 31O is shown. The synthetic resin molded body B is
It has the same structure as the pipe joint A shown in FIG. 7, which was explained as a conventional example. That is, the synthetic resin molded body B has one passage 2 and the other passage 3 that are perpendicular to each other in the branching part 1.
The bottom surface 4 of the pipe is smoothly continuous, and a connecting port 6.6 into which a pipe body is inserted extends on both sides of one passage 2.
A concave line 8 and a convex line 9 are formed along the circumferential direction on the entire length of the branch l in the outer wall 7 forming one passage 2, and the end face shape cut along the axis of the outer wall 7 is It has a waveform formed by the grooves 8 and the protrusions 9. The tube T is pushed out into the one passageway 2, and its lower end is clamped and closed by a clamp 400. Therefore, the pressure of the air blown from the nozzle 310 is effectively used to inflate the tube T. Moreover, a predetermined magnitude of tensile force in the axial direction is applied to the tube T. This tensile force is applied by pulling the clamp 400 downward in the direction of arrow X. The magnitude of the tensile force is such that when the tube T is pressed against the inner surface of the concave strip 8 by blowing air into the tube T to inflate it while applying the tensile force, the tube T is pushed into the inside of the convex strip 9. For example, the tube T is set to such an extent that the tube T is stretched in the axial direction. In this way, the tube T is heat-sealed to the inner surface of the groove 8 with its inner surface kept smooth. Note that it is useful to keep the synthetic resin molded body B at the fusion temperature in advance for reliable heat fusion.

After the tube T is heat-sealed to the inner surface of the grooved strip 8 in this manner, the upper end of the tube T is cut off with a cutting tool 210. Then, the synthetic resin molded body B with the tube T integrated therein is removed from the mold 200 as shown in FIG. 4.

Next, the opening at the intersection between the unnecessary portion A of the tube T protruding from the branch portion 1 of the synthetic resin molded body B and the other passage 3 shown by the chain line in FIG. 4 is cut out.

As a result, the pipe joint A shown in FIG. 5 (which has the same structure as the pipe joint A shown in FIG. 1) is obtained.

Reference numeral 16 indicates an opening opened by cutting out the above-mentioned crossing point opening.

In this manufacturing method, the tube T may be cured before or after the synthetic resin molded body B is removed from the mold 200. This may be done before or after the mouth is removed.

The synthetic resin for molding the synthetic resin molded body B and the tube T should be appropriately selected depending on the purpose and usage conditions of the pipe fitting A. For example, when the pipe joint B is used to connect the above-mentioned underdrain drain pipe or sewer pipe, low-density or high-density polyethylene resin, ethylene diphenylamine resin, or the like can be suitably used. Furthermore, when the pipe joint B is used to connect the above-mentioned underdrain drain pipe or sewage pipe, the thickness of the inner wall 15 is 2
A thickness of ~3 cranes is sufficient, and it is desirable that the thickness of the outer wall 7 be slightly thicker than that. This is because the strength of the outer wall 70 determines the earth pressure resistance, and the strength of the inner wall 15 has no direct relation to the earth pressure resistance.

The method for manufacturing a pipe joint according to the third invention includes the step of cutting off the intersection opening of the tube T to open the opening 16, which is one of the steps included in the method for manufacturing the pipe joint A according to the fourth invention. This has been omitted.

〔Effect of the invention〕

The pipe joints of the first and second inventions have an outer wall with grooves and protrusions that function as reinforcing ribs, and an inner wall with a smooth inner surface, so that sufficient earth pressure resistance is ensured. Of course, this has the advantage that water flows smoothly and solids mixed in water are less likely to accumulate.

The manufacturing method of the pipe joint of the third and fourth inventions does not simply inflate the tube in a plastic state with air pressure and heat-seal it to the inner surface of the groove on the outer wall. Since the inner surface of the tube is kept smooth by applying a tensile force in both directions at the same time, it is possible to prevent the tube from being pushed into the inside of the ridges on the outer wall by air pressure. Therefore, it becomes possible to manufacture the pipe joint of the first or second invention.

[Brief explanation of the drawing]

FIG. 1 is a partial sectional view showing how the pipe joint according to the embodiment of the first invention is used; FIG. 2 is a partial sectional view showing how the pipe joint according to the second embodiment of the invention is used; The figure is a partial sectional view for explaining the manufacturing method of the pipe joint according to the embodiment of the fourth invention, FIG. 6 is a plan view of the T-shaped pipe joint, and FIG. 7 is a portion showing the state of use of the conventional pipe joint. FIG. l...branch, 2...one passage, 3...other passage, 4...bottom, 6...connection port, 7...outer wall,
8... Concave strip, 9... Convex strip, 15... Inner wall, 16.
... Opening, 100 ... Tube body, 300 ... Die for synthetic resin extrusion, 310 ... Nozzle, B ... Synthetic resin molded body, T ... Tube, X ... Applying tensile force Direction, mouth...intersecting point. Patent applicant Takiron Co., Ltd. Figure 4 Figure 5

Claims (1)

[Claims] 1. Connection ports into which the pipe is inserted extend on both sides of the passage, and grooves and protrusions are formed along the circumferential direction on the outer wall of the passage between the two connection ports. , and that the end face shape cut along the axis of this outer wall has a wavy shape formed by the grooves and the protrusions, and the inner wall with a smooth inner surface is integrally joined to the inner surface of the grooves. Characteristic pipe fittings. 2. The bottom surfaces of one passage and the other passage that intersect with each other at the branching part are smoothly continuous, and connecting ports into which the tube is inserted extend on both sides of one passage, and one passage is formed. Concave lines and convex lines are formed along the circumferential direction of the entire length of the branch part in the outer wall, and the end face shape cut along the axis of this outer wall has a waveform formed by the concave lines and convex lines. The inner wall is smooth, and the inner wall extending the entire length of one passage is integrally joined to the inner surface of the groove, and an opening is opened in the inner wall at the intersection of this inner wall and the other passage. A pipe joint featuring: 3. Connection ports into which the tube is inserted extend on both sides of the passage, and grooves and protrusions are formed along the circumferential direction on the outer wall of the passage between the two connection ports, and the axis of this outer wall extruding a tube made of plasticized synthetic resin from a synthetic resin extrusion die into the passageway of the synthetic resin molded body whose end face shape cut along the grooves and ridges has a wavy shape; A pipe joint characterized in that by blowing air into the tube while applying a tensile force in the axial direction to inflate the tube, the tube is thermally fused to the inner surface of the groove while keeping the inner surface of the tube smooth. Production method. 4. The bottom surfaces of one passage and the other passage that intersect each other at the branching part are smoothly continuous, and connecting ports into which the tube is inserted extend on both sides of one passage, and one passage is formed. Concave lines and convex lines are formed along the circumferential direction of the entire length of the branch part in the outer wall, and the end face shape cut along the axis of this outer wall has a waveform formed by the concave lines and convex lines. A tube made of plasticized synthetic resin is extruded from a synthetic resin extrusion die into one of the passages in the synthetic resin molded body, and air is blown into the tube while applying a tensile force in the axial direction to inflate the tube. Therefore, after heat-sealing this tube to the inner surface of the groove while keeping the inner surface of the tube smooth, an opening is created in the tube by cutting the tube at the intersection of the tube and the other passage. Features: Manufacturing method for pipe fittings.