DE20311834U1 - Screw connection element and protective cover therefor - Google Patents

Abstract

The pipe connection (1) is provided with an outer thread (6, 8) located at one end (4) and an inner thread (5, 7) at the opposite end, both areas (3, 4) divided by a shoulder (11). A suitable sealing material like a strand of hemp (9) is pre-inserted into the outer thread (6, 8). The complete element (1) is accommodated insiDEa flexible cover (10) following the outer contours of the element (1), which can either be sold separately or as a unit in combination with the inner element (1).

Description

DE 8513 Patent Attorney

Graduate Physicist

Reinfried Frhr. v. Schorlemer

Karthäuserstr. 5A 34117 Kassel Allemagne

Telephone/Telephone (0561) 15335

(0561)780031 Fax/Telecopier (0561)780032

Harald Schneider, 34134 Kassel,
Martin Schneider, 34272 Fuldabrück

Screw connection element and protective cover for it

The invention relates to a screw connection element according to the preamble of claim 1 and a protective cover applied or applicable to its external thread section.

Pipes, components with pipe-like connections, valves, fittings, etc., as well as connectors and extension pieces for these are always connected to one another using screw connections, particularly in the sanitary and heating sector, but also in mechanical engineering. For this purpose, one of the parts to be connected has an external thread section and the other part a corresponding internal thread section. Since both parts are usually flowed through by a fluid in the form of a liquid or a gas (e.g. water or air), the screw connections must not only meet the mechanical strength requirements, but also be fluid-tight at the usual pressures (e.g. up to 10 bar).

While meeting the strength requirements is not a problem, producing a durable seal still presents difficulties. Although it is common practice to seal the external thread sections with hemp fiber before joining,

However, this measure has not proven to be sufficient, regardless of whether the interacting thread sections are made of metal or plastic. One main reason for this is that the quality of the seal mostly depends on the care taken by the people applying the sealant and then making the screw connection. In the commercial sector, it can be assumed that good seals are achieved in most cases, but the number of unusable seals is still far too high. In addition, it is often overlooked that screw connections often have to be turned back by up to 90° after tightening, for example to straighten a fitting that is crooked and therefore visually unsightly. Such back turns often result in the initially tight screw connection becoming leaky.

To avoid such problems, it is known to provide one of the threaded sections with an integrated sealant at the factory, for example by producing the threads at least partially from an elastic material such as PEX or EPDM (EP 1 004 804 Al) or by providing a threaded section with an annular groove and a sealing element inserted into this (EP 0 544 111 Bl, EP 0 751 328 Al). In addition, separate sealing elements are known, each of which has a stop ring that can be screwed onto an external thread section and a sealing compound made of rubber, plastic (Teflon) or similar that is attached to the stop ring and can be pulled onto the external thread section and which is squeezed together when the screw connection is made between the stop ring and the internal thread section (EP 0 523 775 Al). However, all of these measures have so far proven to be unsatisfactory.

Based on this, the present invention is based on the object of creating a screw connection element and a protective cover suitable therefor, by means of which a permanently tight screw connection can be produced in a simple manner, which can also be turned back by up to 90° without becoming leaky, by means of which a person producing the screw connection can also essentially

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independent sealing effect is achieved and by means of which, as required, a factory pre-assembly can be carried out or a separate accessory can be produced for repair work or the like.

The characterizing features of claims 1 and 13 serve to solve this problem.

The invention has the advantage that all sealing materials that have proven to be suitable, in particular hemp fibers, can be used as sealants. If these are to be applied at the factory in order to relieve the respective craftsman or the like of this work, the protective cover according to the invention serves in particular the purpose of holding and securing the sealant in the threads of the screw connection element during transport and storage. If, on the other hand, it is desired to ensure that the sealant can be applied easily and safely even during repair work or the like, the sealant is expediently integrated into the protective cover and the protective cover is also designed in such a way that it can also be screwed onto an external thread section subsequently or at any desired time. Regardless of how it is manufactured, the protective cover according to the invention also ensures that a screw connection that has been made can be turned back by at least 90° if necessary without the connection becoming leaky. Finally, it is also advantageous that no additional tools are required at the construction site to apply a sealant.

Further advantageous features of the invention emerge from the subclaims. 25

The invention is explained in more detail below in conjunction with the accompanying drawings using exemplary embodiments in which identical parts are provided with identical reference numerals. They show:

Fig. 1 is a longitudinal section through a first embodiment of a screw connection element according to the invention;

Fig. 2 shows, on a scale reduced compared to Fig. 1, a longitudinal section through a screw connection produced with the screw connection element according to Fig. 1;

Fig. 3 is a longitudinal section through a second embodiment of a screw connection element according to the invention;

Fig. 4 shows, on a scale reduced compared to Fig. 3, a longitudinal section through a screw connection produced with the screw connection element according to Fig. 3;

Fig. 5 and 6 longitudinal sections through an inner and outer part of a protective cover according to the invention; and

Fig. 7 shows a protective cover according to the invention, composed of the parts according to Figs. 3 and 4.

Fig. 1 shows a screw connection element 1 in the form of a tubular nipple or extension piece, preferably made of metal. The screw connection element 1 has a longitudinal axis 2 and two connection ends 3 and 4. The connection end 3 is provided with an internal thread section 5 and the connection end 4 with an external thread section 6. Each thread section 5, 6 has, in the usual way, a plurality of threads 7 and 8, respectively, which are formed by channels running helically around the longitudinal axis 2 and are arranged between ribs which, for example, have essentially triangular cross sections.

The threads 8 of the external thread section 6 are provided with a sealing agent 9 which is applied at the factory and in the exemplary embodiment consists of twisted hemp fibers, each of which is indicated by six small circles. It is clear that this is preferably a longer bundle of hemp fibers, as is usual, which is inserted into the threads 8 from one or the other end of the external thread section 6 and therefore runs like them in a helical shape around the longitudinal axis 2.

According to the invention, the screw connection element 1 is further provided with a protective cover 10 made of a flexible material, preferably plastic, which is designed in the manner of a sleeve and is essentially cylindrical and is arranged coaxially on the external thread section 6. The protective cover 10 has an inner diameter that corresponds essentially to the nominal diameter of the external thread section 4, so that it tightly encloses the outer circumferential surface of the external thread section 6. As a result, the sealing agent 9 is held firmly and captive in the threads 6 as long as the protective cover 10 is arranged on the external thread section 6. The protective cover 10 therefore expediently has such an axial length that it covers all the threads 8 filled with the sealing agent 9.

On a rear side, the protective cover 10 is preferably provided with a radially outwardly projecting mounting flange 10a which, in the pulled-on state according to Fig. 1, rests against a radially outwardly extending shoulder 11 which is provided at the rear end of the external thread section 6. It is also particularly expedient to attach the mounting flange 10a to the shoulder 11 with an adhesive so that the protective cover 10 cannot be accidentally stripped off the external thread section 6.

In a further development of the invention, a thread 8a of the external thread section 6 remains free of the sealing agent 9 at a front end of the connection end 4. At this point, the protective cover 10 is deformed by shrinking after heating or by radial pressing in with a pliers-like tool so that it enters the thread 8a and preferably rests against its walls, as Fig. 1 clearly shows. This creates a positive connection between the connection end 4 and the protective cover 10 in the direction of the longitudinal axis 2.

The protective cover 10 can, for example, consist of a sleeve produced by deep drawing, which has a peripheral wall a few hundredths of a millimetre thick and

e.g. made from PA 6, PET, PTFE and other hydroscopic materials, deep-drawable films or the like. Alternatively, it can also be made from hemp or cellulose, for example. For this purpose, a liquefied cellulose mass obtained by melting hemp fibers could be spread onto a mandrel in a layer thickness of up to a few tenths of a millimeter and, after drying, pulled off the mandrel as a finished molded part. To facilitate this process, the mandrel could first be coated with a release agent. A sleeve produced in this way, which has a cardboard-like consistency after drying, can then be pulled onto the external thread section 6.

The protective cover 10 has so far been described as a part that is manufactured separately and only later connected to the connection end 4. This has the advantage that the screw connection elements 1 and the protective covers 10 can be manufactured by different manufacturers and the protective covers 10 can be attached to the connection ends 4 where the sealant 9 is inserted into the threads 8. Alternatively, the protective cover 10 can also be manufactured as an integral element that is firmly connected to the external thread section 6 from the outset. For this purpose, for example, a liquid plastic or cellulose mass is placed in an immersion bath and the connection end 4 is soaked in this immersion bath so that the cover material lies firmly against the outer peripheral wall of the connection end 4 and partially penetrates into the threads 8 and 8a. In this case, the screw connection element 1 and the protective cover 10 form a ready-made prefabricated unit.

Irrespective of the manufacturing process described, there is the advantage that the protective cover 10 can be applied after the sealing agent 9 has been introduced and then protects the external thread section 6 not only against accidental detachment of the sealing agent 9, but also against mechanical damage or damage to the sealing agents that could arise as a result of handling the screw connection elements 1 as bulk goods during transport, storage or any other use prior to the actual application.

Furthermore, the protective cover 10 ensures that the user is not faced with the task of having to insert the sealant 9 into the threads 8 when assembling the screw connection element 1, for example with a second such screw connection element 14 (Fig. 2). Rather, the user only needs to screw the connection end 4 provided with the protective cover 10 with its front end first into a connection end 16 of the screw connection element 14 to be coupled, which is provided with a corresponding internal thread 15. The flexible protective cover 10 is pressed into the threads 8 by the internal thread section 15 together with the sealant 9. If the protective cover 10 is sheared off when the thread sections 6 and 15 are screwed in further due to the effect of the sharp-edged ribs forming the threads, this does not represent a disadvantage. On the one hand, as Fig. 2 shows, the sealant 9 has already penetrated between the front threads and is pressed into them, while on the other hand, as a sheared-off part 10b in Fig. 2 indicates, the protective cover 10 is only gradually stripped off the external thread section 6, so that the sealant 9 safely penetrates into the gaps between the thread sections and thereby ensures the necessary sealing. This is all the more true when hemp fibers are used as a sealant, as the initial ends of these fibers are already firmly clamped between the first threads of parts 1 and 14 after they have been brought together and can then no longer be pushed or pulled away.

The protective cover 10 is suitably made of a soft and flexible material so that it can easily enter the threads of the parts to be joined together with the sealant 9 when the screw connection is made.

However, it would also be possible to use harder materials and to remove the protective cover 10 at the construction site immediately before joining the threaded parts 8 and 15. Even in such a case, it is ensured that the sealant 9 is arranged in the threads 8 of the external thread section 6 with the required distribution and in the required quantity before the screw connection is made.

In addition to the measures described, the sealant can be moistened with a permanently elastic adhesive or any suitable bonding agent before application in order to hold it securely in the threads 8 before application or, if necessary, after stripping off the protective cover 10. However, care must be taken to ensure that only food-safe materials are used in the case of screw thread elements 1 or 14 for drinking water pipes or the like. This also applies to an adhesive used, for example, to attach the protective cover 10 to the shoulder 11 (Fig. 1).

The embodiment 25 of the screw connection element according to the invention shown in Fig. 3 differs from that according to Fig. 1 in that it has only one external thread section 6. The screw connection element 25 is designed as the end of a fitting unit 27 that can be connected to a wall-mounted supply line 26 for water or the like. The supply line 26 has an internal thread section 5 at one end that is adapted to the external thread section 6. The fitting unit 27 and the supply line 26 can be connected to one another via the thread sections 5, 6, wherein the protective cover 10 according to the invention provided on the external thread 6 of the screw connection element 25 (Fig. 4) is pressed into the threads 8 by the internal thread section 15 together with the sealing agent 9, as described with reference to Fig. 2. As indicated by reference numeral 10c in Fig. 3, the part of the protective cover 10 located in the thread 8a according to Fig. 3 remains between the internal and external thread sections 5, 6.

The embodiment according to Fig. 5 to 7 differs from that of Fig. 1 to 4 in particular in that a pocket-like protective cover 18 (Fig. 7) is provided and a sealing means 19 is integrated into the protective cover 18.

The protective cover 18 contains an inner part 20 according to Fig. 5 and 7 and an outer part 21 according to Fig. 6 and 7. The inner part 20 has an inner wall 22 which is adapted to a given external thread section (e.g. the external thread section 6 according to Figs. 1, 3).

to which the protective cover 18 is to be attached. The wall thickness of the inner wall 22 is only a few hundredths of a millimeter thick and is designed in a zigzag shape in longitudinal section corresponding to the elevations and depressions of an external thread, as Fig. 3 clearly shows. The inner wall 22 therefore has an inner internal thread section with threads 22a which fits onto the external thread section of e.g. the screw thread element 1, and a correspondingly shaped external thread section with threads 22b. At the rear end, the inner wall 22 is provided with a radially outwardly projecting mounting flange 22c which, when mounted, is intended to rest against the shoulder 11 according to Figs. 1, 3.

The shape of the outer part 21 corresponds essentially to the shape of the protective cover 10 of Fig. 1 and 2. In contrast, however, the inner diameter of the outer part 21 is preferably slightly larger than the outer diameter of the inner part 20 so that a gap 23 is formed between the two, as is indicated in a broken part of Fig. 7. This gap 23 serves as a receiving space for the sealing means 19, which, as in the case of Fig. 1 and 2, can consist of hemp fibers or of sealing materials corresponding to an application, which are inserted in particular into the threads 22b of the inner part 20 formed on the outside of the inner wall 22 and wound in the axial direction in a helical manner. At its rear end, the outer part 21 has a mounting flange 21a projecting radially outwards, analogous to Fig. 1, while at the front end it is provided with an indentation or bead 21b, analogous to Fig. 1 (Fig. 7).

After the sealing agent 19 has been inserted into the threads 22b or the gap 23, the outer part 21 is pulled onto the inner part 20 coaxially to a common longitudinal axis 24 until the mounting flanges 22c, 21a lie against one another. Both mounting flanges 22c, 21a can then be connected to one another by gluing, welding or by a suitable joining process. In addition, after being pulled onto the inner part 20, the outer part 21 is provided with the indentation 21b analogously to Fig. 1 and 2, which enters an external thread 22b of the inner part 20 that is free of the sealing agent 19. In contrast to Fig. 1 and 2, on the one hand

the sealing means 19 is not directly in the threads of the respective screw thread element 1, but in the threads of the thin inner part 20, while on the other hand the outer part 21 is not attached directly to the screw thread element 1, but to correspondingly designed sections of the inner part 20. It is clear that the inner diameter of the outer part 21 essentially corresponds to the outer diameter of the inner part 20 and the intermediate space 23 can therefore essentially be formed by the V-shaped external threads 22b of the inner part 20.

The protective cover 18 according to Fig. 5 to 7 offers the advantage that it can be subsequently screwed coaxially onto the external thread sections 6 of screw connection elements 1 of the appropriate size, e.g. on a construction site. This is particularly desirable for repair work when a connection made with an existing screw thread element has become leaky. However, as in the case of Fig. 1 and 2, it is also possible to screw the protective covers 18 onto the screw thread elements 1 at the factory in order to provide them with a factory-applied sealant 19 and to protect this and the threads of the screw thread elements 1 during transport, storage, etc.

The inner part 20 preferably consists of a soft, pliable material, since it remains intact after being applied to an external thread section 6 and should not only penetrate into the threads, e.g. of the screw thread element 1, but also, if possible, into all grooves or the like present in these, when a radially inward-acting pressure is exerted on the sealant when the screw connection is joined. The outer part 21, however, like the protective cover 10 according to Figures 1 to 4, can consist of a harder material and can be sheared off or pushed backwards when the screw connection is joined, as indicated in Figures 2, 4 by reference number 10b, or remain between the internal and external thread sections (5, 6) when joining.

The parts 20 and 21 can be manufactured essentially in the same way as described above for the protective cover 10 which is to be manufactured separately.

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The protective covers 10 and 18, with their sections that can be pulled onto the external thread sections 6, can be essentially cylindrical or slightly conical or can be otherwise adapted to the thread shapes of the screw thread elements, as may be necessary, for example, in the case of screw thread elements that are provided with NPT threads (National Pipe Taper), BSP threads (British Standard Pipe), etc.

The advantage of hemp sealants is that hemp swells when it gets wet and therefore has no tendency to leak, but at most creates an even stronger seal. Alternatively, other sealants can also be used, preferably with corresponding properties. In the case of Fig. 5 to 7, it would even be conceivable to use flowable materials that are pressed deep into the threaded sections to be sealed when the screw connection is joined.

The invention is not limited to the embodiments described, which could be modified in many ways. This applies in particular to the sizes, materials and shapes of the various parts provided for in individual cases.

The screw connection element according to the invention can be designed for connection to such a device. It is also understood that a screw connection element according to the invention can be attached firmly or detachably to pipes, valves, fittings or the like and serves to tightly connect these to corresponding counterparts.

Above all, the protective covers described can be manufactured and offered in different sizes according to the standard sizes of the usual screw thread elements. But the measures given above for attaching the protective covers to the screw thread elements or the individual parts of the protective covers to each other can also be varied as required. The manufacture of the protective covers is also in principle possible within wide limits.

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It is also clear that the protective covers 10, 18 at their front ends, ie where they are to be screwed into a corresponding internal thread section,
be suitably provided with insertion bevels or designed in another way to facilitate the insertion process. Finally, it is understood that the various features can also be used in combinations other than those described and illustrated.

Claims (27)

1. Screw connection element with an external thread section ( 6 ) and a sealing means ( 9 , 19 ) arranged in its threads ( 8 ), characterized in that it is provided with a protective cover ( 10 , 18 ) surrounding the external thread section ( 6 ), made of a flexible material and intended for holding the sealing means ( 9 , 19 ) in the threads ( 8 ). 2. Screw connection element according to claim 1, characterized in that the protective cover ( 10 ) is applied to the external thread section ( 6 ) by a dipping or spraying process. 3. Screw connection element according to claim 1, characterized in that the protective cover ( 10 ) consists of a sleeve produced by deep drawing and pulled onto the external thread section ( 6 ). 4. Screw connection element according to claim 2 or 3, characterized in that the protective cover ( 10 ) is provided on its rear side with a mounting flange ( 10a , 22c ). 5. Screw connection element according to claim 4, characterized in that the mounting flange ( 10a , 22c ) rests against a shoulder ( 11 ) provided at the rear end of the external thread section ( 6 ) and can be connected to this. 6. Screw connection element according to claim 5, characterized in that the mounting flange ( 10a , 22c ) can be connected to the shoulder ( 11 ) by gluing. 7. Screw connection element according to one of claims 3 to 6, characterized in that a thread ( 8 a) located at the front end of the external thread section ( 6 ) is free of sealing means ( 9 ) and the protective cover ( 10 ) is positively connected to this thread ( 8 a) in the axial direction of the external thread section ( 6 ). 8. Screw connection element according to claim 7, characterized in that the positive connection is produced by shrinking or pressing in. 9. Screw connection element according to one of claims 1 to 8, characterized in that the sealing means ( 9 ) lies directly on the threads ( 8 ) of the external thread section ( 6 ) and the protective cover ( 10 ) has an inner diameter which corresponds substantially to the outer diameter of the external thread section ( 6 ). 10. Screw connection element according to one of claims 1 to 9, characterized in that the protective cover ( 18 ) contains an inner part ( 20 ) with an inner wall ( 22 ) adapted to the external thread section ( 6 ) and an outer part ( 21 ) surrounding the inner part ( 20 ), the sealing means ( 19 ) being arranged between the inner and the outer part ( 20 to 21 ). 11. Screw connection element according to claim 10, characterized in that the inner and outer parts ( 20 , 21 ) can be firmly connected to one another. 12. Screw connection element according to claim 10 or 11, characterized in that the inner and outer parts ( 20 , 21 ) can be connected to one another in a form-fitting manner at their front ends in the axial direction. 13. Screw connection element according to one of claims 10 to 12, characterized in that the inner and outer parts ( 20 , 21 ) are connected by gluing or welding mounting flanges ( 21a , 22c ) provided at their rear ends. 14. Screw connection element according to one of claims 1 to 13, characterized in that the sealing means ( 9 , 19 ) is formed from a long-fiber or a thread-like material. 15. Protective cover for a screw connection element ( 1 , 25 ) which is provided with an external thread section ( 6 ) intended to receive a sealing agent ( 9 , 19 ), consisting of a sleeve intended to be pulled onto the external thread section ( 6 ). 16. Protective cover according to claim 15, characterized in that it has an inner diameter substantially corresponding to the outer diameter of the external thread section ( 6 ). 17. Protective cover according to claim 15 or 16, characterized in that it contains an inner part ( 20 ) with an inner wall ( 22 ) adapted to the external thread section ( 6 ) and an outer part ( 21 ) surrounding the inner part ( 20 ) and is provided with a sealing means ( 19 ) between the inner and outer parts ( 20 , 21 ). 18. Protective cover according to claim 17, characterized in that the inner and outer parts ( 20 , 21 ) can be firmly connected to one another. 19. Protective cover according to one of claims 15 to 18, characterized in that the inner and outer parts ( 20 , 21 ) are positively connected to one another at their front ends in the axial direction. 20. Protective cover according to one of claims 15 to 19, characterized in that the inner and outer parts ( 20 , 21 ) are connected by gluing or welding mounting flanges ( 21a , 22c ) provided at their rear ends. 21. Protective cover according to one of claims 15 to 20, characterized in that the sealing means (9, 19) is formed from a long-fiber or a thread-like material. 22. Protective cover according to claim 21, characterized in that the sealing means ( 19 ) consists of hemp fibers. 23. Protective cover according to one of claims 15 to 22, characterized in that the inner and outer parts ( 20 , 21 ) are formed from a composite material. 24. Protective cover according to one of claims 15 to 23, characterized in that the inner and outer parts ( 20 , 21 ) contain protein-containing fibers. 25. Protective cover according to one of claims 15 to 23, characterized in that the inner and outer parts ( 20 , 21 ) contain cellulose. 26. Protective cover according to one of claims 15 to 23, characterized in that the inner and outer parts ( 20 , 21 ) contain mineral components. 27. Protective cover according to one of claims 15 to 22, characterized in that the inner and outer parts ( 20 , 21 ) each contain at least one polymer.