HK1022511A1 - Compression fitting for pipes - Google Patents

Abstract

The connection is between a pipe fitting with connection socket (2) and e.g. an aluminum plastic-jacketed installation pipe (8) with press sleeve (10). A snap ring (9) forms a snap connection with the press sleeve. It also has a collar suitable for guiding and positioning the press jaws (11) of compression pliers. The snap ring has apertures and/or consists of a transparent material. It holds the end face of the installation pipe at a distance to the pipe fitting.

Description

The invention relates to a device for the manufacture of a marketable pipe connection within the meaning of claim 1.

The end of a pipe (usually made of plastic-metal composite material) is pushed over a connecting rod of a fitting. A concentric press shell overlapping the pipe is placed over that . The pipe is positioned in the combined state above the connecting rod and then the pressure is fluidized by means of a transverse pressure. The pressure backs are however a local cross section followed by a local pressure difference in the shape of the water line. For example, a 0-2 or 0-19 axis is used to increase the pressure between the two conductors.

Although the above-mentioned type of sliding pipe connections give satisfactory results in most cases, studies have shown that the different materials of the fitting on the one hand and the plastic-metal composite of the installation pipe on the other hand cause different tensions at the sealing surfaces.

The purpose of the invention is to improve a pipe connection of the type described at the outset so as to give a perfect seal effect even at temperatures and pressures not corresponding to the nominal values in normal operation. This is achieved by the development of conventional pipe connections known, for example, from EP-A-589 413, as indicated in the definitive part of the attached claim 1.The O-ring is placed in a region of the fitting's connecting support in which the press groove rejuvenates the press sleeve and/or the installation tube in cross section. The latter design adaptation to the press groove zones is appropriate in view of the large number of press grooves used by installation companies. The essential thing is that the function of the pressed O-ring is maintained and thus its permissible limits of deformation (e.g. 15%) are not exceeded. The material deformation of the installation tube must not lead to a flow of material into the O-ring shape, otherwise an obstruction of the O-ring in its use will occur.In the case of pressing, it is irrelevant whether the press-blades of the press-slip have one or more continuous ring surfaces, e.g. 8 mm wide, or whether the press surfaces are dissolved into radially spaced, e.g. square, individual surfaces, or whether parallel ring coils are provided for pressing, preferably with triangular cross-section in precision zones adjacent to each other. The O-ring may also be subject to pressing action by the fact that the press surfaces are located directly next to the O-ring.

The design of the invention is particularly useful if between the pressed O-ring and the pressed surface structure (ring nut) of the connecting bracket, another O-ring is placed, preferably unpressed and elastically deformable. The pressed O-ring is sealed in cold water in the temperature range below 20°C and at pressures below 2 bar. The O-ring which is not subjected to additional pressing is sealed when operating pressure occurs - e.g. at 6 bar and retains the sealing properties even at higher temperatures, thus also at 90°C.

The combination of an additional O-ring with a non-compressed O-ring and a structured zone with a spread results in a tightness in all areas and mechanical strength against tensile stress.

An example of a pipe assembly which can be sold according to the invention is shown in the diagram.

A pipe fitting 1 has a connecting tube 2 at its end, which carries two ringnuts 3, 4 for each O-ring 5, 6. The ringnut 3 is bounded on both sides by ringnuts. Furthermore, the connecting tube 2 ends in a region structured by ringnuts 7. On the connecting tubes 2 an installation tube 8 is suspended. This is an aluminium tube with plastic coating on both sides or a plastic tube with metal snap or, if appropriate, an aluminium tube without special coating. The suspension is limited by a snap spring 9 consisting of a break on a spindle or by a pre-pressed material to prevent the complete or single-pressure of the installation tube 8 and a pre-pressure of the aluminium tube 9 to prevent corrosion. On the other hand, a contact between the tube and the inserted tube 9 can be checked to prevent any risk of corrosion.

A pressing rod has several press-backs which are moved radially against the press sleeve 10 in a clamp motion to locally rejuvenate the cross-section there and thus form a press connection. The figure shows a press-backs 11 in cross-section with two ring-segment pressing surfaces 12, 13 before the pressing operation. After pressing, the press-surfaces 12, 13 are pressed as negatives into the press sleeve 10. These permanent insertions act on the installation tube 8 and the latter deforms the O-ring 5 in addition to the deformation in the starting position (B-deformation). The final deformation is within the limits of the function of the O-ring as prescribed by the standard. It is below the limit of the installation ring. The material used is not free of the O-ring 3 edge, the material itself is not free of the 9 edge of the installation ring.

The positioning of the presses 11 is achieved by the collar of the snapper 9 which is placed in a deep ringnut of the presses 11 and the presses are symmetrically formed so that the press tool or the press handle can be used on the left and right.

The press surface 13 of the press bar 11 or the press surface marked as negative in the press casing 10 presses the installation pipe 8 irreversibly into the surface structure, i.e. into the ring nuts 7 of the pipe support 2. This creates an increased holding force and a special resistance of the pipe connection to tensile stresses.

Between the two press surfaces 12 and 13, the O-ring 6 is located, its deformation is not enhanced by an additional diameter of the installation tube 8 but is in the standard base deformation.

Water at high temperature and operating pressure (e.g. in a central heating system) diffused by the mechanical press connection in the area of ring nuts 7 below the press surface 13. The high pressure causes the O-ring 6 to deform in such a way that it is reliably sealed. The O-ring 5 remains inoperative - except for statistical leakage rates.

The O-ring 6 can also be placed under a press surface, which would provide even better sealing for the operating case, but if the low pressure and cold water temperature phases alternate with higher pressure and temperature phases, the design according to the example gives the best results.

Claims (6)

1. A device for producing a compressible pipe connection between a connecting piece of a pipe fitting and a conduit, such as an aluminium pipe covered on both sides with plastic, comprising

   - a connecting piece (2) provided for the conduit (8) and having a surface-structured, e.g. grooved region, the conduit (8) being mountable on the connecting piece (2),

   - a pressure sleeve (10) slidable over the conduit (8),

   - a connecting member serving to connect the connecting piece (2) to the pressure sleeve (10),

   - at least one O-ring (5) for sealing the connection between the connecting piece (2) and the conduit (8), and

   - a pressure clamp, by means of which compression can take place between the pressure sleeve (10) and consequently also the conduit (8) in such a manner that at least one pressure surface extending in the circumferential direction of the conduit (8) is formed between the conduit (8) and the surface-structured region of the connecting piece (2), wherein the at least one O-ring (5) is arranged below a pressure surface (12) or directly adjacent to such a pressure surface (12) or directly between two pressure surfaces in the pressure sleeve (10) or in the conduit (8) and has deformation caused by the pressure below the pressure surface (12) and corresponding to the admissible deformation of the O-ring (5), and/or at least one non-compressed and elastically deformable O-ring (6) is arranged between the connecting piece (2) and the conduit (8),

   characterised in that the connecting member is formed as a snap ring (9) which on the one hand forms a snap-locking connection to the pressure sleeve (10) and on the other hand has a shape suitable for guiding and positioning the pressure jaws (11) of a pressure clamp, wherein the snap ring has a collar serving to guide the pressure jaws (11) of the pressure clamp and being arranged in a deep annular groove in the pressure jaws for the guiding and positioning thereof.
2. A device according to claim 1, characterised in that the snap ring (9) has openings and/or at least partly comprises a transparent material.
3. A device according to claim 1 or 2, characterised in that the end surface of the conduit (8) is held apart from the pipe fitting by the snap ring (9).
4. A device according to any one of the preceding claims, characterised in that a further, preferably non-compressed and elastically deformable O-ring (6) is arranged between the compressed O-ring (5) and the compressed surface structure (annular grooves 7).
5. A device according to any one of the preceding claims, characterised in that the O-ring (5) is arranged in an annular groove (3) bounded on either side by a further annular groove.
6. A device according to any one of the preceding claims, characterised in that the pressure surface is formed as a circular cylindrical annular surface.