JPH0890653A - Assembly method of plastic pipe and plastic socket - Google Patents

Abstract

(57) [Abstract] [Purpose] To create a method in which a plastic socket is connected to a plastic pipe easily and securely even if both are made of polyolefin. In a method for assembling a plastic pipe and a plastic socket, a finished socket (12) having a welding surface is used, and a pipe (11) having an opposing surface to the welding surface is used, and the welding surface and the opposing surface are An electrically heatable welding mat (1) which is fitted to each other and is shaped correspondingly to the welding surface and the counter surface is arranged between the welding surface and the counter surface, is supplied with electric current and is provided with a socket (12 ) And the pipe (11) are pressed against each other.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for assembling a plastic pipe and a plastic socket according to the preamble of claim 1.

[0002]

BACKGROUND OF THE INVENTION For the manufacture of pipe assemblies, it is basically necessary that the pipe section comprises a socket tightly connected to the pipe, which, on the other hand, does not have a sealing ring. It is related to how raw materials are to be omitted. This is especially important for sewers where relatively short pipe sections are used.

A simple pipe, in other words a homogeneous wall pipe that is not a composite pipe, can be made from PVC. Such a pipe is secondarily socketed, in other words, the end portion of the pipe is heated and then expanded with a mandrel. European Patent Application Publication No. 2715598
No. (EP 0 271 598 A2) discloses such a method which is also for twin wall pipes having a smooth inner pipe and a corrugated outer pipe. Problems arise when the socket is fitted, in other words, there is a risk of the outer corrugated pipe breaking when expanded. this is,
It is very time consuming and requires a slow heating process. If the pipe consists of a polyolefin, such as polyethylene, secondary socketing is not possible, or only to a very limited extent, because of the so-called memory effect of the plastic.
If such a pipe socket were secondarily reheated, it would take on its original geometric profile. The socket is not dimensionally stable.

European Patent Publication No. 231446 (EP
0 231 446 B1, corresponding to US Pat. No. 4,779,651) discloses on-line production of sockets on twin walls by means of a casting machine. Since polyolefin requires high cooling capacity, the production speed on the casting machine is relatively low, which makes it uneconomical to mold the socket in a twin wall pipe.

US Pat. No. 3,897,090 (US-Patent 3
897 090) teaches forming a socket in a simple corrugated pipe on a casting machine.

In order to prevent problems when the twin wall pipe is fitted with a socket, it is known from EP 271598 to injection mold the socket at the end of the twin wall pipe. . This is complicated and the pipe must also be enclosed in the corresponding injection tool, but with satisfactory results. The equipment requirements are very large.

It is an object of the present invention that a plastic socket is simply and securely connected to a plastic pipe, even if both are made of polyolefin.
To create a general type of method.

[0008]

According to the invention, this object is achieved by the characterizing part of claim 1. The procedure according to the invention is applicable to pipes of all shapes,
Ensure that the socket is provided without the need for any special equipment. The method can be used for pipes with homogeneous walls and according to claim 3 for corrugated pipes and according to claim 4.
It can also be used for twin wall pipes. The socket is manufactured by injection molding or extrusion.
If the socket is manufactured by injection molding, the welding mat may already be integrated into the socket during injection molding. The welding mat can already be placed in the injection tool when the socket is manufactured. Welding with the welding mat is quick. This detail is dependent on dependent claims 2-1.
It becomes clear from 1. According to claims 12 and 13, the method according to the invention is also used for producing a double plug-in socket from two equal sockets with a very short pipe section.

[0009]

Further features, details and advantages of the invention will become apparent from the description of an embodiment of the invention in connection with the drawings.

1 and 2 show a so-called welding mat 1 having an electric resistance wire 2. The wire comprises a plastic cover that is the same as, or at least welds to, the plastic of the parts to be welded together. This wire 2 with a plastic cover 3 is arranged in a serpentine shape, with the individual straight sections 4 abutting parallel to each other and without gaps. It will be understood from this how the welding mat 1 shown in FIGS. 1 and 2 is formed. The mat can be curved parallel to the longitudinal direction 5 of the part 4. Furthermore, the welding mat 1 can be curved around the main longitudinal direction 6. Two longitudinal directions 5 and 6
Are located on the main plane of the welding mat 1 corresponding to the plane of FIG. Further, the welding mat 1 can be deformed by being separated on one side in a concertina shape in the main plane formed by the paper surface of FIG. 1, and the separation is performed perpendicular to the paper surface and around an axis line (not shown). .
In this case, the arch portions 7 located on the one longitudinal side are spaced apart to some extent, and the arch portions 8 on the opposite side remain closed together. The straight sections 4 extending in the longitudinal direction 5 are no longer exactly parallel to each other. At the two ends of the welding mat 1 of the length required for the particular application, the two parts 4 are bent and serve as current terminals 9, 10. A welding mat 1 of this type is basically known, for example, from European Patent Publication No. 146775 (EP 0 146 775 B1).

FIG. 3 shows a twin wall pipe 11 to which the socket 12 is to be fixed. The twin wall pipe comprises a smooth, cylindrical inner pipe 13 and a corrugated outer pipe 14, and the base 15 of the corrugated portion 16 of the outer pipe and the inner pipe 13 are welded together. The corrugated portion 16 has flank portions 17 and 18, and an annular web 19 integral with the flank portions. The manufacture of such a twin wall pipe 11 is generally known and is described in European Patent Publication No. 65729 (EP 065 729 B1, US Pat. No. 44925).
(Corresponding to No. 51) and described in detail. In effect
The socket comprises a cylindrical portion 20, the inner diameter d _{20 of which} is slightly larger than the outer diameter d _{11 of} the twin wall pipe 11, and a twin wall pipe equal to the twin wall pipe 11 is pushed into the socket 12. At one end of the cylindrical portion 20, the socket 12 has an annular chamber 22 which opens towards the inside, i.e. towards the central longitudinal axis 21 of the twin wall pipe 11 and the socket 12 for the accommodation of the sealing ring. Due to such a seal that is at least crimped against the annular web 19 of the corrugations 16, an annular chamber 22 in the direction of the axis 21 is provided.
Has a length a which exceeds the outer distance b between two adjacent corrugations 16 or between two adjacent annular webs 19, respectively. In fact, the seal would relate to a homogenous pipe inserted in the socket 12 or a twin wall with a cover pipe. The annular chamber 22 is followed by an inlet 23, which is for the same pipe as the twin wall pipe 11 and extends in a funnel shape.

A weld flange 24 is formed at the end of socket 12 opposite lead-in 23. This welding flange 2
4 comprises a frusto-conical portion 27 extending parallel to the facing flank 17 of the corrugated portion 16 and a cylindrical portion 26 extending parallel to the adjacent portion 25 of the base 15 of the corrugated portion 16. The welded portion 24 is a transitional portion 28 that follows the cylindrical portion 26.
To connect to the cylindrical portion 20 of the socket.

As shown in FIG. 3, the welding mat 1 which is deformed into the substantially L shape as described above slides on the portion 25, and the welding mat 1 is in contact with the portion 25 of the cylinder portion 26 and the flank. And a frusto-conical portion 27 in pressure contact with the portion 17. The wire 2 extends so that the originally straight portion 4 is on the page. The wire is part 25 and flank 1
Extends along 7, and then upside down again. The inner diameter d ₂₆ of the cylinder portion of the welding flange 24 is larger than the outer diameter d ₁₅ of the portion 25 of the base portion 15 of the corrugated portion 16 by twice the thickness c of the welding mat 1. The socket 12 is integrally formed by injection molding, and is made of the same polyolefin as the twin wall pipe 11.

As shown in FIG. 4, the socket 12 and the twin wall pipe 11 press against each other in the direction of the central longitudinal axis 21, the welding flange 24 presses tightly against the parts 26 and 27 of the welding mat 1, The welding mat 1 is pressed firmly against the flank 17 and the portion 25.
An electric current is supplied via the terminals 9 and 10 to heat the welding mat 1 and melt the plastic cover 3 of the welding mat and the adjacent parts of the welding flange 24 and the flanks 17 and 25. When they are sufficiently melted, the electric current is cut off and the molten plastic material is cooled, so that the socket 1
2 and the twin wall pipe 11 are durable welded.

For the description of all the following examples, the same parts are given the same reference numbers, and like-functioning but slightly different structurally parts are given the same reference numbers with a dash or two-dash. Therefore, repeated explanations will be omitted.

As shown in FIG. 5, the twin wall pipe 11 'is provided with an auxiliary cover pipe 29 on the outer side thereof,
It significantly increases the annular stiffness. Welding of the socket 12 and the twin wall pipe 11 'is carried out in the same way as in the embodiment according to FIGS. FIG. 6 shows a socket 12 ′ provided with ribs 30 on the cylindrical portion, which ribs give the socket the same rigidity as the twin wall pipe 11. Again, socket 12 '
The welding mode of the twin wall pipe 11 is the same as that of the embodiment shown in FIGS.

FIGS. 7 and 8 show a twin wall pipe 11 which is equivalent to the pipe according to FIGS. 3, 4 and 6. Socket 12 ″ differs from that described above due to the design of welded flange 24 ″. The weld flange 24 ″ has a cylindrical portion 26 ″, the inner diameter d ″ _{26 of which} is the outer diameter d of the portion 25.
_It is almost equal to ₁₅ . The frusto-conical portion 27 ″ extends parallel to the flank 17 and has a cylindrical outer portion 31. The welding mat 1 is bent in a C shape and is located at least partially on the flanks 17 and 18 of the corrugated portion 16 on the annular web 19 of the corrugated portion. FIG. 7 shows the pre-assembled position of the socket 12 ″ and the twin wall pipe 11, while FIG. 8 shows the socket 12 ″ and the twin wall pipe 11 after welding. Again, the socket 12 '' and the twin wall pipe 11 are being welded together, in other words the terminals 9, 1
When 0 supplies current, they are pressed against each other in the direction of the axis 21 and / or in a radial direction with respect to the axis 21.

9 to 11 show a twin wall pipe 11
The state where the socket 32 is applied to is shown. Socket 32
Is manufactured from a cylindrical annular homogeneous wall pipe that is commercially available for the socket portion of the homogeneous wall pipe. Such homogeneous wall pipes are manufactured by extrusion. The portion 32a of the cylindrical inner surface 33 of the socket 32 to be joined to the twin wall pipe 11 has a thickness c of the welding mat 1 at the outer diameter d ₁₁ of the corrugated portion 16, that is, the annular web 19 of the twin wall pipe 11. It is machined so that the inner diameter d ₃₃ corresponds to the size obtained by adding 2 times. The welding mat 1 folds around an axis 21 to form an annular portion 34 and firmly abuts the annular web 19 of two adjacent corrugations 16. Inner surface 33 of annular web 19 and socket 32 when current is applied to terminals 9, 10.
Weld with related parts of. The portion 32b where the twin wall pipe 11 and the socket 32 are not welded to each other has an inner diameter d.
₃₃ has an inner diameter smaller than ₃₃ , and the annular neck 32c is
Formed at the location where b enters the portion 32a, the annular neck 32c also serves as a coplanar stop for the annular portion 34 of the welding mat 1 and can be pushed into the portion 32a.

In order to prevent excessive deformation of the twin wall pipe 11 in the vicinity of the annular web 19 which forms the corrugated ridge, in the embodiment according to FIG. 10 a split or grooved ring 35 is provided. , Base 15
And has a cross-sectional area that substantially corresponds to the flanks 18 and 17 defining this, and is located in the space between two adjacent corrugations 16. On the outer surface, this ring 35 is placed in substantial alignment with the adjacent annular web 19.

In the embodiment according to FIG. 11, the twin wall pipe 11 'provided with the cover pipe 29 is used as it is provided in the case of the embodiment according to FIG. In this case, the socket 32 'portion 32'a of the outer diameter d of the cover pipe 29' has a ₃₃ 'inside diameter d' of the inner surface 33 corresponding to the plus twice the thickness c of the welding mat 1 to ₁₁ . In the embodiment according to FIGS. 9 to 11, during welding, each of the parts 32a and 32'a is pressed from the outside against the twin wall pipe 11 or 11 'in the radial direction with respect to the axis 21.

FIG. 12 shows the assembly of the socket 12 ″ and the twin wall pipe 11. Socket 1
The 2 "cylindrical part 20 is a twin wall pipe 1
It slides over the annular web 19 of the first corrugated portion 16. The cylindrical portion 20 is followed by an equally annular cylindrical welding flange 24 ′ ″, the inner surface of which is the annular neck 3.
It is pushed into the part 20 by 3a. In the welding flange 24 ″ ′, the welding mat 1 formed as an annular portion 34 presses against the annular jaw 33 a and the cylindrical portion 2
The position is adjusted to 0. Injection molded socket 12 '''
During the manufacture of the welding mat 1, the welding mat 1 can be tightly integrated by being placed in an injection tool prior to injection molding. Again, the weld flange 24 '''is
During welding, it is pushed against the twin wall pipe 11 in a radial direction with respect to the axis 21.

FIG. 13 shows an embodiment corresponding to FIGS. 3 and 4, in which the welding mat 1 is already tightly integrated with the welding flange 24 of the socket 12. For this, it is prewelded and placed in an injection molding tool.

FIG. 14 shows an embodiment of the socket 12 ″ as shown in FIGS. 7 and 8. In this case, the homogeneous wall pipe 41 is connected to the socket 12 ″, and the front part 42 of the homogeneous wall pipe 41 is the welding flange 24 ″ of the socket 12 ″.
It conforms to the shape of.

In the embodiment according to FIG. 15, two identical sockets 12 in a mirror-symmetrical arrangement are connected to the segment 36 of the twin wall pipe 11. This segment 36 shows the corrugated part 16 and the relevant part of the inner pipe 13. This segment 36 and the socket 12 mirror-symmetrically arranged
The connection is made in the same way as in the embodiment according to FIGS. The welding mat 1 welds the welding flange 24, the flank 17 and the part 25 of the base 15 of the socket 12 shown on the left side of the figure to one another, while the other socket 12
Welding flange 24, flank 18 of corrugated portion 16 and base 1
5 and part 37 are welded together. From this it will be seen how a double-plug socket is manufactured.

In the embodiment according to FIG. 16, the two sockets 12 and the annulus 38, which are arranged mirror-symmetrically to each other, are welded together, the annulus comprising an internal pipe section 39 and flanks 17 ', 18'. And an outer pipe section 40. The respective cylindrical section and the respective frusto-conical section of the welding mat 1 are pipe sections 39, 4 exhibiting dimensions as described above in connection with the embodiment according to FIGS.
It is in contact with 0. In this case, the outer pipe section 40 functions as a corrugated section. Even in this way, a double bayonet socket can be manufactured from two identical sockets 12.

In the embodiment according to FIG. 17, as can be seen from FIG. 12, two sockets 12 ′ ″ arranged in mirror symmetry with respect to each other have three corrugations in the same way as applied to FIG. 12. Twin wall pipe 1 having section 16
Connect to 1. In this way, too, a double bayonet socket to be used in particular for the assembly of the twin wall pipe 11 can be manufactured from two identical sockets 12 '''. In this case, a welding mat 1 in the form of an annular part 34 is used, which slides over the part of the twin wall pipe 11. Then, the socket 12 ″ ′ is arranged.

[0027]

The present invention provides a method of assembly in which a plastic socket is connected to a plastic pipe in a simple and secure manner, even if both are made of polyolefin.

[Brief description of drawings]

FIG. 1 is a plan view of a welding mat.

FIG. 2 is a cross-sectional view of the welding mat according to the line II-II of FIG.

FIG. 3 is a view showing a socket and a twin wall pipe in a pre-assembled state before welding.

FIG. 4 shows the twin wall pipe and socket according to FIG. 3 after welding.

FIG. 5 is a view showing a state in which a twin wall pipe having an auxiliary cover pipe and a socket are welded together.

FIG. 6 is a view showing an improved embodiment of a twin wall pipe provided with a socket.

FIG. 7 shows an improvement of the welded joint of the twin wall pipe with the socket in the pre-assembled state.

FIG. 8 shows the twin wall pipe and socket according to FIG. 7 in the welded state.

FIG. 9 is a view showing a twin wall pipe provided with a cylindrical socket.

FIG. 10 is a diagram showing an embodiment completed in relation to FIG.

FIG. 11 shows an embodiment according to FIG. 9 with a twin wall pipe with a cover pipe.

FIG. 12 is a view showing an improved embodiment of a twin wall pipe provided with a socket.

FIG. 13 shows a slightly modified embodiment of a twin wall pipe with preassembled sockets in relation to FIGS. 3 and 4.

FIG. 14 shows an embodiment according to FIGS. 3 and 4 of a socket, installed in a homogeneous wall pipe.

FIG. 15 shows a short twin wall pipe section with two welded sockets.

FIG. 16 shows a short homogeneous pipe section with two welded sockets.

FIG. 17 shows a short section of a twin wall pipe with two welded sockets.

[Explanation of symbols] 1 welding mat 2 electric resistance wire 3 plastic cover 11 pipe 12 socket 32 socket 36 pipe

Claims (17)

[Claims] 1. A finished socket (1) having a welding surface.
2, 12 ', 12 ", 12'", 32, 32 ') are used, and the pipe (1
1, 11 ', 36, 38, 41), the welding surface and the counter surface are matched to each other, and an electrically heatable welding mat shaped corresponding to the welding surface and the counter surface ( 1)
Are arranged between the welding surface and the counter surface, and current is supplied to the welding mat (1), and sockets (12 ′ ″, 32,
32 ') is at least partially pressed against the pipe (11, 11') or the socket (12, 12 ', 12'')
And a pipe (11, 36, 38, 41) are pressed against each other, a method for assembling a plastic pipe and a plastic socket. 2. A welding mat (1) comprising an electrical resistance wire (2) having a plastic cover (3) is used, said plastic cover (3) and socket (1).
2, 12 ', 12 ", 12'", 32, 32 ') plastic parts and pipes (11, 11', 36, 38, 4)
Method according to claim 1, characterized in that the plastic part of 1) is weldable to each other and the wire (2) is laid so as to form a mat. 3. Each corrugation (16) has two flanks (1).
7, 18, 17 ', 18') and a corrugated pipe (11, 1) defined by an annular web (19) integrating them.
1 ', 36, 38) are used, and two corrugations (16) adjacent to each other are integrated by a corrugated base (15). 4. A method according to claim 3, characterized in that a twin wall pipe (11, 11 ') is used which has a smooth inner pipe (13) surrounded by a corrugated pipe (14). 5. The welding mat (1) comprises at least one flank (17, 18, 17 ′, 18 ′) of the flank (16).
It is press-contacted with respect to Claim 3 or 4
The method described in. 6. The welding mat (1) is in pressure contact with the portion (25) of the corrugated base (15).
5. The method according to any one of 5 to 5. 7. The welding mat (1) is substantially L in the cross-section area.
The method according to claim 5, wherein the method has a character shape. 8. Method according to claim 3, characterized in that the welding mat (1) is arranged at least against the outer annular web (19) of the corrugations (16). . 9. Method according to claim 5 or 8, characterized in that a welding mat (1) is used which is substantially C-shaped in the cross-sectional area and which overlaps the corrugations (16). 10. Welding sockets (32, 32 ') having a cylindrical welding surface are used, wherein a cylindrically shaped welding mat (1) comprises at least one annular web of welding surface and corrugations (16). 19) The method according to any one of claims 1 to 4 and 8, characterized in that it is arranged between the two. 11. Method according to claim 10, characterized in that the support ring (35) is arranged between two adjacent corrugations (16). 12. Method according to claim 1, characterized in that an annular pipe section (36, 38) with two sockets (12) welded together is used as a pipe. 13. A segment (3) of a twin wall pipe (11) having at least one corrugation (16).
Method according to claim 12, characterized in that 6) is used as a pipe. 14. Sockets (12, 12 ′, 12 ″, 1)
Method according to any one of claims 1 to 13, characterized in that 2 ''') is produced by injection molding. 15. The socket (32, 32 ') is manufactured by extrusion molding.
The method according to any one of 3 above. 16. Method according to claim 14, characterized in that the welding mat (1) is tightly connected with the socket (12, 12 ′, 12 ″, 12 ′ ″) during injection molding. . 17. Socket (12 ′ ″, 32, 32 ′)
During welding the part of the pipe in the radial direction (11, 11 ')
The method of claim 1, wherein the method is pressed against.