CA2325451A1

CA2325451A1 - Pipe connection

Info

Publication number: CA2325451A1
Application number: CA002325451A
Authority: CA
Inventors: Rainer Franzen; Herbert Foering
Original assignee: Individual
Current assignee: Mapress GmbH and Co KG
Priority date: 1998-03-24
Filing date: 1999-02-23
Publication date: 1999-09-30
Also published as: PT1064488E; KR20010034610A; DE59901191D1; WO1999049255A1; PL343128A1; DE19813805C1; EP1064488B1; ATE216043T1; JP2002507713A; ES2172324T3; CN1291268A; DK1064488T3; EP1064488A1

Abstract

The invention relates to a pipe connection, consisting of a press fitting with at least one section which has a torus-like cross-section and which accommodates a sealing ring, an adjoining cylindrical section oriented towards the insertion end and/or such a section oriented away from the insertion end. The cylindrical section oriented away from the insertion end runs into an adjacent cylindrical section, forming a stop. The inner diameter of the latter cylindrical section is smaller than the other cylindrical sections. The pipe connection also consists of a conduit whose flat end area comes to rest on the inner stop of the press-fitting after being inserted into the same. A nondetachable, tight pipe connection is produced by closing a pressing tool with at least two pressing plates encompassing the press fitting. During the pressing process, the pressing plates act on the torus, including the sealing ring placed therein, and on the cylindrical section of the press fitting oriented towards or away from the insertion end. The invention is characterised in that an element (14, 21) which only allows the inserted conduit (4) to move backwards axially within a fixed limit is situated in the area of the cylindrical section (9, 25) oriented away from the insertion end, the inside clearance of said element when not under stress being smaller than the smallest possible outer diameter (18) of the inserted conduit (4) in terms of tolerance.

Description

Pipe connection Description The invention relates to a pipe connection comprising a press fitting and a conduit, which is inserted in said press fitting and connected in a non-releasable manner thereto, according to the preamble of patent claim 1.
A pipe connection with a fitting which encloses the smooth pipe ends and of which the ends, which are of bead-like design, each accommodate a sealing ring, it being the case that an exchangeable retaining device which is connected to an actuating device and has articulated jaws is used to deform the bead-like end and, at the same time, the adjacent cylindrical region of the fitting together with the pipe plastically and the enclosed sealing ring elastically, is known (see extract from the "Mannesmann Pressfitting GmbH"
brochure, issue 8/1994). The sealing function of the connection is achieved in that, by virtue of plastic deformation of the bead-like end, the sealing ring is deformed elastically and, over a certain part of the cross-sectional circumference, comes into abutment linearly against the enclosing surface regions of the bead-like end of the fitting and of the pipe. For the purpose of absorbing the longitudinal forces which occur with corresponding internal pressure, that cylindrical region of the fitting which is adjacent to the bead-like end, together with the pipe, is deformed plastically. During the pressing operation, the bead-like end and the adjacent cylindrical region are deformed at the same time by means of the actuating device.
It is pointed out on pages 13 and 14 of the brochure that, for a reliable press connection, the correct insertion length for the conduit is extremely important. In this case "correct insertion length" is intended to mean that, before the pressing operation, the conduit is intended to be inserted axially, with a slight rotary action and simultaneous pressing action, as far as the stop produced by the bead-like depression of the press fitting. A previously provided marking on the conduit serves as a control means here.
However, in order to achieve a practical sequence of operations, a conduit is not always laid, on site, step by step, i.e. measuring, cutting to size, deburing, marking, inserting and pressing; rather, a plurality of conduit sections which are to be connected are simultaneously measured and inserted and, finally, all the connecting locations are subjected to a pressing action. With this method of operation, however, it is not possible to rule out the situation where the measuring, in particular in narrow-angled space conditions, was not exact and the conduit, which may possibly have been cut to too short a size, cannot any longer be inserted fully into one or even two press fittings or, following alignment of the line at one location, the already inserted conduit is drawn some way out of the press fitting again. Since it is not always possible to see this rearward displacement from the outside, if, for example, the necessary insertion length is not marked correctly or the marking was incomplete (non-visible rear side), the pressing operation nevertheless takes place. Depending on the degree of rearward displacement, such a defective pressing location, as a result of the movement of the line, may subsequently lead to leakages, and possibly also to the connection being released.
Another pipe connection is known from JP 55-88939.
This pipe connection comprises a press fitting which has at least one section which receives a sealing ring in a cross-sectionally bead-like manner and an adjoining, first cylindrically designed section, which is directed toward the insertion side. Provided on the other side of the annular bead is a second cylindrically designed section, which is of smaller internal diameter, with the result that it forms a stop. The transition from the annular bead to the second cylindrically designed section takes place via a step which merges with rounded shaping into the two adjacent regions. In this case, the step serves as a guide for the inserted conduit. The smooth end region of the conduit which is to be connected comes into abutment, following insertion, against the stop of the second cylindrically designed section. By means of a pressing tool, which encloses the press fitting and has two or more pressing jaws, a non-releasable, sealed pipe connection is formed following the closure of the pressing jaws, it being the case that, during the pressing operation, the pressing jaws act both on the annular bead, including the sealing ring positioned therein, and on the first cylindrically designed section of the press fitting.
The problem concerning the correct insertion length is the same as has already been described in detail above.
For this reason, this pipe connection has the same disadvantages as the first-mentioned pipe connection.
The object of the invention is to specify a pipe connection that comprises a press fitting and a conduit, which is inserted therein, and, following the pressing operation, allows compensation in length within a fixed limit without any risk of sealing being lost.
This object is achieved, taking the preamble as the departure point, in conjunction with the defining features of patent claim 1. Advantageous developments form the subject matter of the subclaims.
The invention proposes to arrange in the region of the cylindrically designed section which is directed away from the insertion side a means which allows the inserted conduit to be moved back axially only within a fixed limit, it being the case that the inside width of said means, in the non-loaded state, is smaller than the smallest tolerance-induced external diameter of the inserted conduit. Said means is preferably a ring produced from an elastic material. For example, said ring may be a sheet-metal ring which is bent in the form of a U, as seen in cross section, and of which the legs are located in the insertion direction of the conduit.
In order to achieve a certain claw action, the leg which rests on the conduit has a curved end region directed toward the conduit. Alternatively, the ring may have at least one inwardly extending nose which is inclined slightly in the insertion direction of the conduit. The means may be produced from a metallic material or from plastic or from a metal/plastic composite material.
The advantage of the proposed pipe connection can be seen in that, although the means allows a rearward movement, this rearward movement becomes increasingly difficult, until the means comes into abutment against the sealing ring or against a stop, with the result that further rearward movement is prevented. In this position, the production of a sealed pipe connection is ensured since there is still a sufficient length of the rearwardly moved conduit located in front of the sealing ring. The axial length of the means is as short as possible and is selected, in relation to the length of the second cylindrically designed section, which is directed away from the insertion side, or that of the intermediate section, such that a sufficient compensating length of a number of millimeters remains.

The pipe connection designed according to the invention will be explained in more detail, with reference to a number of exemplary embodiments, in the drawing, in which:
Figure 1 shows a longitudinal section of half a pipe connection designed according to the invention, Figure 2 shows the same as Figure 1, but with the capacity for rearward movement being illustrated, Figure 3 shows a longitudinal section of half of a second embodiment of a pipe connection designed according to the invention, Figure 4 shows the same as Figure 3, but with the capacity for rearward movement being illustrated, Figure 5 shows a variation of the embodiment illustrated in Figure 3, and Figure 6 shows the same as Figure 5, but with the capacity for rearward movement being illustrated.
Figure 1 illustrates a longitudinal section of half a pipe connection designed according to the invention. Said pipe connection comprises a press fitting 1 with an outwardly extending section 2, which is of bead-like design, and a sealing ring 3, which is positioned in said section, and a conduit 4, which is pushed into the press fitting 1. The bead-like section 2 merges in a known manner, via a flank 5, into a first cylindrically designed section 6 located in the insertion direction. The insertion direction is marked by an arrow 7. On the other side of the bead-like section 2, the flank 8 merges, according to the invention, into a second cylindrically designed section 9. Said section 9 has a larger internal diameter 10 than the internal diameter 11 of the first cylindrically designed section 6. The second cylindrically designed section 9 merges into a third cylindrically designed section 12, forming a stop for the inserted conduit 4 in the process, the internal diameter 13 of said last-mentioned section being smaller than the internal diameter 11 of the first cylindrically designed section 6. This means that a stop is formed for the inserted conduit 4. Arranged, according to the invention, in the region of the second cylindrically designed section 9 is a means which inhibits the rearward movement of the inserted conduit 4, the means in this exemplary embodiment being a sheet-metal ring 14 which is bent in the form of a U and of which the legs 15, 16 are located in the insertion direction 7. In order to achieve a certain claw action, the leg 16, which is directed toward the conduit 4, is provided with a curved end region 17, which is directed toward the conduit 4.
The sheet-metal ring 14 is placed in position, together with the sealing ring 3, during the production of the press fitting 1. In this non-loaded state, the inside width of the sheet-metal ring 14 is smaller than the smallest tolerance-induced external diameter 18 of the inserted conduit 4, with the result that the sheet-metal ring 14 is compressed elastically following the insertion of the conduit 4.

_ g _ Figure 2 shows the capacity for rearward movement of the inserted conduit 4 in order for it to be possible to cover, for example, a certain compensation in length of the previously laid line. As a result of the friction, the rearward movement becomes increasingly difficult, until the sheet-metal ring 14 comes into abutment against the sealing ring 3. If a pressing operation takes place in this position, sealing is ensured since there is a sufficient length of the end region of the inserted conduit 4 located in front of the sealing ring 3.
Figure 3 illustrates a longitudinal section of half of a second embodiment of a pipe connection designed according to the invention, the same designations having been selected for the same elements. This pipe connection comprises a press fitting 20 with a section 2 which extends outward in a bead-like manner and a sealing ring 3, which is positioned in said section, and a conduit 4, which is pushed into the press fitting 20. The bead-like section 2 merges in a known manner, along a flank 8, into a first cylindrically designed section 9 located counter to the insertion direction. The insertion direction is marked by an arrow 7.
At the end of the extent of the first cylindrically designed section 9, the latter merges into a second cylindrically designed section 12, forming in the process a stop for the conduit 4 which is to be pushed in. The internal diameter 13 of said second cylindrically designed section 12 is in the region of the internal diameter 19 of the inserted conduit 4 and is smaller than the internal diameter 10 of the first cylindrically designed section 9. Arranged, according to the invention, in the region of the first cylindrically designed section 9 is a means which inhibits the rearward movement of the inserted conduit 4. In this exemplary embodiment, said means is a ring 21 with an inwardly extending nose 22. The nose 22 is inclined, to be precise in the insertion direction 7. The ring 21 is placed in position, together with the sealing ring 3, during the production of the press fitting 20. In this non-loaded state, the inside width of the ring 21 is smaller than the smallest tolerance-induced external diameter 18 of the inserted conduit 4, with the result that the ring 21, following the insertion of the conduit 4, is compressed elastically.
Figure 4 shows the capacity for rearward movement of the inserted conduit 4. As a result of the friction, the rearward movement becomes increasingly difficult, until the ring 21 comes into abutment against the sealing ring 3. If a pressing operation takes place in this position, sealing is ensured since there is a sufficient length of the inserted conduit 4 located in front of the sealing ring 3. In order that the sealing ring 3 is not damaged by the ring 21 during the rearward movement, the ring 21 has a rounded section 23 at the end region directed toward the sealing ring 3.

Figure 5 shows a variant of the embodiment illustrated in Figure 3. In contrast to the latter, there is provided in the first cylindrically designed section 9 of the press fitting 24 a cylindrically designed intermediate section 25, of which the internal diameter 26 is larger than that of the first cylindrically designed section 9. At the end of the extent, the intermediate section 25 merges into the second cylindrically designed section 12, forming a stop for the inserted conduit 4 in the process, the internal diameter 13 of said last-mentioned section being in the region of the internal diameter 19 of the inserted conduit 4.
Arranged, according to the invention, in the region of the intermediate section 25 is a means which inhibits the rearward movement of the inserted conduit 4. Said means is designed, as illustrated in Figure 3, as a ring 21 with a nose 22 located in the insertion direction 7. However, it would equally be possible for the sheet-metal ring 14 illustrated in Figure 1 to be used as the means which inhibits the rearward movement.
Figure 6 shows that, in contrast to Figure 4, the capacity for rearward movement of the inserted conduit 4 is bounded by the shoulder 27 of the intermediate section 25 rather than by the sealing ring 3. The resulting maximum possible compensating length 28 is indicated by arrows.

Claims

claims

1. A pipe connection comprising a press fitting (1, 20, 24) which has at least one section (2), which is of cross-sectionally bead-like design, and accommodates a sealing ring (3), and adjoining cylindrically designed sections (6, 9), which are respectively directed toward and away from the insertion side, or just one cylindrical section (9), which is directed away from the insertion side, it being the case that the cylindrically designed section (9), which is directed away from the insertion side, merges into an adjoining cylindrically designed section (12), forming a stop in the process, the internal diameter (13) of said last-mentioned section being smaller than the internal diameter (10, 11) of the other cylindrically designed sections (6, 9), and also comprising a conduit (4), of which the smooth end region, following insertion into the press fitting (1, 20, 24), comes into abutment against the inner stop of the press fitting (1, 20, 24), and a non-releasable, sealed pipe connection is formed by means of a pressing tool, which encloses the press fitting (1, 20, 24) and has at least two pressing jaws, following closure of said tool, it being the case that, during the pressing operation, the pressing jaws act both on the annular bead (2), including the sealing ring (3) positioned therein, and on the cylindrically designed section (6, 9) of the press fitting (1, 20, 24) respectively directed toward and/or away from the insertion side, wherein arranged in the region of the cylindrically designed section (9, 25), which is directed away from the insertion side, is a means (14, 21) which allows the inserted conduit (4) to be moved back axially only within a fixed limit and of which the inside width, in the non-loaded state, is smaller than the smallest tolerance-induced external diameter (18) of the inserted conduit (4), it being the case that the axial length of the means (14, 21) is as short as possible and is selected, in relation to the length of the cylindrically designed section (9), which is directed away from the insertion side, such that a sufficient compensating length of a number of millimeters remains.

2. The pipe connection as claimed in claim 1, wherein the means is a ring consisting of an elastic material.

3. The pipe connection as claimed in claim 2, wherein the ring is designed a sheet-metal ring (14) which is bent in the form of a U, as seen in cross section, and of which the legs (15, 16) are located in the insertion direction (7) of the conduit (4).

4. The pipe connection as claimed in claim 3, wherein the leg (16), which is located on the conduit (4), has a curved end region (17) directed toward the conduit (4).

5. The pipe connection as claimed in claim 2, wherein the ring (21) has at least one inwardly extending nose (22).

6. The pipe connection as claimed in claim 5, wherein the nose (22) or the noses is/are inclined slightly in the insertion direction (7) of the conduit (4).

7. The pipe connection as claimed in claims 1 and 2, wherein the means (14, 21) is produced from a metallic material.

8. The pipe connection as claimed in claims 1 and 2, wherein the means (14, 21) is produced from plastic.

9. The pipe connection as claimed in claims 1 and 2, wherein the means (14, 21) is produced from a metal/plastic composite material.

10. The pipe connection as claimed in one of claims 1-9, wherein the press fitting (1) has a first cylindrically designed section (6), which adjoins the annular bead (3) and is directed toward the insertion side, and a second cylindrically designed section (9), which is directed away from the insertion side and of which the internal diameter (10) is larger than that (11) of the first cylindrically designed section (6), and the second cylindrically designed section, in the end region, merges into the third cylindrically designed section (12), forming a stop for the inserted conduit (4) in the process, the internal diameter (13) of said last-mentioned section being in the region of the internal diameter (19) of the inserted conduit (4) and always being smaller than the two first-mentioned cylindrically designed sections (6, 9).

11. The pipe connection as claimed in one of claims 1-9, wherein the press fitting (20, 24) has a first cylindrically designed section (9), which adjoins the annular bead (2), is directed away from the insertion side and, in the end region of the extent, merges into the second cylindrically designed section (12), forming a stop for the inserted conduit (4) in the process, the internal diameter (13) of said last-mentioned section being in the region of the internal diameter (19) of the inserted conduit (4) and always being smaller than the first-mentioned cylindrically designed section (9).

12. The pipe connection as claimed in claim 11, wherein the first cylindrically designed section (9), which is directed away from the insertion side, has a cylindrically designed intermediate section (25), of which the internal diameter (26) is larger than that of the first section (9) and which then merges into the second cylindrically designed section (12), forming a stop in the process.

13. The pipe connection as claimed in claim 12, wherein the axial length of the means (14, 21) is as short as possible and is selected, in relation to the intermediate section (25), such that a sufficient compensating length of a number of millimeters remains.