AU8530598A - Pressure connector for pipes - Google Patents

Description

Pressure connector for pipes The invention relates to a pressure connector for pipes, comprising a press fitting and a line pipe which is inserted into the latter and non-detachably connected to the latter, according to the preamble of Patent Claim 1. A pressure connector of the generic type for pipes is disclosed by JP 55-88939. It comprises a press fitting which has at least one section which is bead-like in cross section and accommodates a sealing ring, and a first cylindrical section adjacent to the latter and facing the insertion side. Provided on the other side of the annular bead is a second cylindrical section which is smaller in internal diameter, so that it forms a stop. The transition from the annular bead to the second cylindrical section is made via a step which runs horizontally and merges in rounded form into the two adjoining regions. In this case, the step serves as a guide for the inserted line pipe. The smooth end region of the line pipe to be connected comes to rest on the stop of the second cylindrical section after it has been inserted. By means of a pressing tool which has at least two press jaws and encloses the press fitting, a non-detachable, tight pressure connection of the pipes is formed after the press jaws have been closed, the press jaws acting during the pressing operation both on the annular bead, including the sealing ring inserted therein, and on the first cylindrical 1 -2 section of the press fitting. The disadvantage with this pressure connector for pipes is that the step between the annular bead and the second cylindrical section forms a relatively long gap which is located horizontally and is wetted by the medium to be transported. Aggressive substances can become enriched in this gap, even during the operation of the line system, since here no flushing action can take place. These aggressive substances can attack the material of the line pipe and/or press fitting. This applies in particular to the industrial application, where carrier liquids to which a wide range of materials have been added are transported through the line system. Another type of pressure connector for pipes is disclosed by US-3,596,939. This comprises a press fitting having at least one section which is bead-like in cross section and accommodates a sealing ring, and a first cylindrical section adjacent to the latter and facing the insertion side, as well as a second cylindrical section facing away from the insertion side, the two sections having the same internal diameter, as well as an inwardly directed bead, adjoining the annular bead, which, forming a stop for the pipe to be inserted, merges in rounded form into the second cylindrical section. Sealing is carried out in such a way that the sealing ring projecting into the interior of the

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-3 press fitting is compressed by the inserted pipe. In order that the sealing ring cannot be pressed out or damaged, the end of the pipe to be inserted is worked on mechanically. This connector is secured axially by means of an indentation made in the first cylindrical section by means of a pressing tool. The disadvantage with this design is that the dimensions of press fitting, sealing ring and inserted pipe must be matched to one another within close limits, and a conventional line pipe with large tolerances cannot be used. The additional working of the end face of the pipe to be inserted is disadvantageous, a relatively long gap being formed thereby in conjunction with the stop bead. The pressures which can be transmitted are limited, as a result of the sealing system. The object of the invention is to develop a pressure connector of the generic type for pipes in such a way that, in addition to the sanitary installation, it is also suitable for line systems in the industrial sector with high internal pressures, using normal line pipes. Starting from the preamble, this object is achieved by the features specified in the defining clause of Patent Claim 1. Advantageous developments are a constituent part of subclaims.

-4 According to the invention, it is proposed, while dispensing with an inner guide for the line pipe to be inserted, to allow the steeply sloping flank of the annular bead, facing the second cylindrical section, to merge in rounded form into the second section without a step. As a result, in the ideal case where there is direct metallic contact between the end face of the inserted line pipe and the stop of the second cylindrical section, virtually no gap is formed. Since the aforementioned faces are not located precisely plane-parallel, taking into account the tolerances and production inaccuracies, a radially located gap will still form at some circumferential points, but this is significantly smaller than the previously usual long horizontal gap. In order to ensure the stop for the line pipe to be inserted, the internal diameter of the second cylindrical section is equal to the internal diameter of the inserted line pipe. Taking the tolerances into account, a deviation upward to plus one half the wall thickness and downward to one times the wall thickness of the inserted line pipe is possible. In order that the lower radial gap does not represent a problem even in extreme applications, the sealing ring is provided with a sealing lip which extends inward. This sealing lip is arranged such that it comes to rest between the end of the inserted line pipe and the stop on the 14 -5 second cylindrical section. This ensures that aggressive substances transported with the carrier liquid can no longer be enriched in this region. The sealing-lip contour should expediently be selected such that the entire sealing area is flushed in such a way that no concentrations can build up. With the effect of designing the pressure connector for pipes so that it is suitable for manual work, it is also proposed to provide the pressure connector for pipes with an anti-withdrawal means. This is intended to achieve the situation where, following the insertion of the line pipe and before the pressing operation which fixes this installed situation, the line pipe is not inadvertently pushed back somewhat, and therefore a gap could in turn be formed. To this end, it is proposed to design the end area of the first cylindrical section to be angled over and to arrange thereon a clip element which prevents the withdrawal of the inserted line pipe. This clip element is preferably designed as a resilient annular sleeve which, with the inner edge, prevents the inserted line pipe from being able to be moved back again without the application of force. In order that the plugged on, annular sleeves are not lost during the transport of the press fittings to the installation site, they have at least one inwardly directed latching means which can latch into a corresponding recess in the end area of the second cylindrical section.

-6 The advantage of the pressure connector for pipes proposed can be seen in the fact that gap formation in the contact area which can be wetted by the medium to be transported between the inserted line pipe and press fitting is prevented in a simple way, and inadvertent gap formation is also reliably prevented by the arrangement of an anti withdrawal means. Stainless steel is preferably used as the material both for the press fitting and for the line pipe for the pressure connector proposed for pipes. This steel is suitable for a wide range of liquids to be transported, in the sense of adequate corrosion protection. The pressure connector for pipes designed in accordance with the invention is explained in more detail in the drawing using a number of exemplary embodiments. In the drawing: Figure 1 shows a half longitudinal section of a pipe connection designed according to the invention. Figure 2 is similar to Figure 1, but following the pressing operation. Figure 3 is similar to Figure 1, but with a modified sealing ring. Figure 4 is similar to Figure 3, but with an additional anti-withdrawal means. Figure 5 shows the anti-withdrawal means on an enlarged scale.

-7 Figure 1 illustrates a half longitudinal section of a pressure connector for pipes designed in accordance with the invention, and Figure 2 illustrates the same pressure connector for pipes following the pressing operation. It consists of a press fitting 1 having a sealing ring 2 inserted therein, and a line pipe 3 inserted into the press fitting 1. The press fitting 1 has, in a known way, a bead like section 4, which merges via a flank 5 into a first cylindrical section 6 located in the insertion direction. The insertion direction is identified by the arrow 7. On the other side of the bead-like section 4, the rapidly falling flank 8 according to the invention merges without a step into a second cylindrical section 9. This section 9 has a smaller internal diameter 10 than the first cylindrical section 6. As a result, a stop 12 for the line pipe 3 to be inserted is formed. In the ideal case, the internal diameter 10 of the second cylindrical section 9 is equal to the internal diameter 13 of the inserted line pipe 3. In such a configuration, the result would be a smooth, eddy-free passage opening for the medium to flow through. The gap 14 which can still be wetted by the medium (illustrated greatly exaggerated here) is located radially and is very much smaller than the horizontal gap known from the prior art. Taking into account the tolerances and production inaccuracies, the internal diameter 10 of the second I

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-8 cylindrical section may have a positive tolerance, specifically up to half the wall thickness 15, or may have a negative tolerance down to one complete wall thickness 15 of the inserted line pipe 3. Figure 3 shows a variant of the pressure connector for pipes designed in accordance with the invention, the same reference symbols having been used for identical parts. In order to seal off the gap which can still be wetted by the medium, the sealing ring 16 has a circumferential sealing lip 17 which extends inward. This is arranged in such a way that it comes to rest between the end face 18 of the inserted line pipe 3 and the stop 12 on the second cylindrical section 9. This ensures that no concentration of the aggressive substances contained in the flowing medium can build up in this area. A further variant having an anti-withdrawal means is illustrated in Figures 4 and 5. Here too, the same reference symbols have been used for identical parts. In order to avoid any inadvertent gap formation as a result of unintentional removal of the inserted pipe from the stop, an annular sleeve 20 is clipped onto the angled-over end region 19 of the first cylindrical section 6. This sleeve 20 consists of a resilient material, for example spring steel, so that as the line pipe 3 is inserted, the lower edge 21 is pressed away upward. However, if one attempts to move the -9 line pipe 3 back again following its insertion, the edge region 21 digs into the outer surface 22 of the line pipe and holds the latter firmly. In order that the sleeve 20 previously plugged on is not lost during the transport of the press fittings 1, said sleeve has, for example, a number of inwardly directed latching means 23, 23'. During the plugging-on operation, these latching means 23, 23' latch into trough-like recesses 24, 24', which are arranged on the upper side and underside of the angled-over end region 19 of the first cylindrical section 6. Of course, other types of transport safeguard are also possible and can be used. Z4417 4U

Claims (1)

1. Pressure connector for pipes, comprising a press fitting which has at least one section which is bead like in cross section and accommodates a sealing ring, and a first cylindrical section adjacent to the latter and facing the insertion side, as well as a second cylindrical section which faces away from the insertion side and, forming a stop, has a smaller internal diameter than the first cylindrical section, and having a line pipe whose smooth end region comes to rest on the stop of the second cylindrical section of the press fitting after it has been inserted into said press fitting and, by means of a pressing tool which has at least two press jaws and encloses the press fitting, a non detachable, tight pressure connection of the pipes is formed after said tool has been closed, the press jaws acting during the pressing operation both on the annular bead, including the sealing ring inserted therein, and on the first cylindrical section of the press fitting, characterized in that the steeply sloping flank (8) of the annular bead (4), facing the second cylindrical section (9), merges in rounded form into the said section (9) without a step, the internal diameter (10) of the second cylindrical section (9) being equal to the internal diameter (13) of the inserted line pipe (3) within a tolerance band of plus one half the wall -12 region (19) of the first cylindrical section (6) has at least one trough-like recess (24, 24'), which is suitable for the latching means (23, 23') to latch into after the annular sleeve (20) has been plugged on.