TUBULAR JOINT

Abstract: A pipe coupling for joining an outer pipe (10) or a bend, whose inner diameter exceeds the outer diameter of an inner pipe (12) insertable into the split (14) end portion of the outer pipe (10). A pipe joining device, structurally simple and simple to assemble, is achieved by forming the end portion of the outer pipe (10) with a pair of cooperating material projections (16a, 16b) at each end split (14), one material projection (16a, 16b) on either side of the end split (14). A pair of cooperating material projections (16a, 16b) have mutually aligned holes for a bolt shank (18), and their end surfaces, facing opposite circumferential directions, form abutment surfaces for the head (20) and the nut (22) of the bolt (18). By such a pipe coupling/joining device the inner pipe (12) does not require any special design, but may be produced in cylindrical form and uniform cross-sectional shape throughout.

Description: TUBULAR JOINT The invention relates to a pipe coupling comprising an outer split pipe end portion for the reception and clamping of a therewith concentric, inner pipe end portion, and in which is used, for the clamping, at least one bolt connection, whose bolt shank extends essentially parallel to a tangent to said pipe in the area of the respective split. In the joining of pipes and bends is often used, according to known technique, an outer pipe with a split end portion, which is slid over the end of an inner pipe, the split end portion of the outer pipe then being tightened on the exterior of the inner pipe by means of at least one annular clamp, which is activated by means of a bolt connection, after having been positioned around the split end portion of the outer pipe. The activation causes the annular clamp to be pressed together, which reduces the circumference/diameter of the outer end portion by utilization of the longitudinal splits. A pipe coupling, of the kind in which annular clamps are used, is for example disclosed in US patent document No. 3 905 623, in which the deformable outer sleeve (10) is placed concentrically outside two pipe end portions (12 and 14) which are inserted one into the other, and has two of said bolt connections arranged thereto, with parallel axes and extending mainly in parallel with tangents to the pipe end portions, inserted one into the other, in the area of the re- spective longitudinal split. These annular clamps and deformable sleeves thus act as the tightening sleeve of the pipe coupling, which sleeve is to place outside the pipe end portions, inserted one into the other, in a separate operation, whereafter the bolt connection(s) is (are) tightened to effect a tightening action, which is necessary to ensure a reliable connection of the pipe end portions inserted one into the other. In said US patent document a particular embodiment (Figs. 10 and 11) is described, in which the outer pipe itself forms the deformable sleeve. However, this construction requires a special configuration of both the outer and inner tube. The construction is rather complex, relatively expensive and difficult to make successfully, because there are strict requirements to accuracy. Therefore, the object of the present invention has been to alleviate defects and drawbacks by previously known techniques, and thus, firstly provide a structurally and operationally very simple pipe coupling of the kind initially mentioned, in which the inner tube does not require any specially formed coupling portion ' at the insertion end portion, and in which there is no need for an external clamping sleeve/ring which makes the pipe coupling more expensive, partly in its purchase price, partly by requiring a separate assembling operation. According to the invention the object is realised by configuring a pipe coupling, of the initially mentioned kind, in accordance with the characterizing part of claim 1. According to the invention, on opposite sides of at least one axial split in the end portion (coupling area) of the outer pipe, are formed material projections from surrounding pipe wall material, which projections are formed with aligned holes for (I) a bolt body of a bolt connection, and (II) for one insert body each respectively, which, again, is formed with said holes for the bolt body of said bolt connection, and (III) for one slide-over body each respectively, which in turn is formed with said holes for the bolt body of said bolt connection, and has a longitudinal slot defining one portion insertable into a respective material projection, while the remaining part of each slide-over body will remain on the outside of the adjacent material projection. In alternative I the ends of the material projections the - selves form abutment elements for the nuts of the bolt connection (stud screw) and head and nut (screw bolt) respectively, an imaginary line through the centres of said aligned holes extending substantially perpendicularly to the adjacent split, and substantially parallel to a tangent to the outer mantle surface of the outer pipe, in the area of said adjacent split. In alternative II the ends of the inserts transversely to the pipes, possibly together with the ends of the material projections, are what forms the abutment for the nuts/head of the bolt connection. In alternative III the ends of the slide-over/insertable bodies are what forms abutment for the nuts of the bolt connection and the head and nut respectively. In this embodiment the projecting material projections are formed themselves with a cross-section approximately rectangular or of almost right-angled U-shape. Embodiment III is particularly well suited for joining pipes of either very thin wall or very thick wall. In pipes of very thin wall the material will not be strong enough to enable use in conjunction with embodiment I, and in pipes of very thick wall it may be problematic to have material projections of essentially triangular cross section, according to alter- native I, pressed outwards to a sufficient extent. In embodiment I each material projection thus forms a guiding for the bolt of the bolt connection and an abutment for a nut (head) . A particularly simple and strongly drawn abutment portion on either side of the split may, according to the in- vention, have an approximately triangular cross-sectional form, tapering in a radially outward direction. Advantageously, in all of the embodiments the outer pipe may have two diametrically opposite longitudinal splits extending axially inwards from the terminal edge of the pipe end por- tion. Non-limiting examples of embodiments of pipe couplings configured according to the invention, will be explained in further detail in the following, in the form of preferred embodiments with reference to the accompanying drawings, in which: Figs. 1 - 3 show a first embodiment. Figs. 4 and 5 a second embodiment and Figs. 6 - 9 a third embodiment. Fig. 1 shows a partial side view of an established pipe coupling, in which the end portion of an inner pipe has been in- serted into the connecting portion of an outer pipe; Fig. 2 shows a cross section corresponding to the sectional plane II-II in Fig. 1; and Fig. 3 shows the connecting portion of the outer pipe after a 90° rotation compared to that in Fig. 1, to show the possi- ble cross-sectional shape of the bolt-guiding material projections; Fig. 4 shows one half of a cross-section through two concentric pipes, in which the outer pipe is formed with material projections in the area of a longitudinal split, inserts, screw bolt with fixed head and tightening nut being shown in split sectional view; Fig. 5 shows the embodiment according to Fig. 4 in the assembled state; Fig. 6 shows one half of a cross-section through two concentric pipes with a pipe joining device according to a third embodiment, slide-over elements, screw bolt with fixed head and tightening nut arranged thereto being shown in split sectional view: Fig. 7 shows the embodiment according to Fig. 6 in the assembled state; Fig. 8 shows a partial side view/planar view in the area of one of the longitudinal splits in the end portion area of the end portion of an outer pipe according to Figs. 6 and 7; and Fig. 9 shows a corresponding partial side view of the end portion of an outer pipe after a 90° rotation relative to that in Fig. 8, to show a rectangular/U-shaped cross- sectional form of the material projections. First, reference is made to Figs. 1 - 3 which show a first embodiment of a pipe coupling/joint in accordance with the present invention. In the drawings reference numeral 10 defines an outer pipe of a pipe coupling/joint in relation to an inner pipe 12 of so much smaller outer diameter than the inner diameter of the outer pipe 10, that the end portion of the inner pipe 12 may be inserted concentrically into the end portion/coupling portion of the outer pipe 10. Over at least a certain axial distance of its end/coupling portion, the outer pipe 10 is configured in the exemplary embodiment with two diametrically placed longitudinal splits 14 , whose axially outer ends open at the terminal edge of the outer pipe 10. In the shown exemplary embodiment the inner pipe 12 has no special configuration, which simplifies the manufacturing and simplifies the assembling. In the area of each longitudinal split 14, there are formed, on the opposite sides thereof, radially projecting material projections 16a, 16b, which have been drawn from surrounding pipe wall portions of the outer pipe. The material projections may be formed through pressing or in other way. As appears from fig. 3, each radially extending material projection 16a, 16b may have a cross-section shaped essentially as an inverted V, the V-point of the cross-section pointing radially outwards from the outer pipe 10. The material projections have mutually aligned through openings which gener- ally extend transversely to the longitudinal axis A of the outer pipe 10, and together form a receiving bore for a screw bolt 18 with a fixed head 20 and a tightening nut 22 at the opposite bolt end portion. The end surfaces of a pair of cooperating material projections 16a, 16b, facing opposite di- rections, form abutting surfaces for respectively the adjacent bolt head 20 and the nut 22. This screw bolt 18,20 may, of course, by replaced by a stud screw with a threaded portion at opposite ends for nuts. When the inner pipe 12 has been inserted by its end portion into the end portion of the outer pipe 10 having not tightened bolt connections 18,20,22 which are subsequently tightened and make the circumferential portion of the outer pipe tighten around the inserted end portion of the inner pipe 12 , whereby the circumference of the coupling portion of the outer pipe is reduced by utilisation of the longitudinal splits 14, the pressing together of the two pipes 10, 12 may be sufficient, not only to establish a strong, reliable joint, but also a safe tightening between the two pipes 10,12. In Figs. 4 and 5 is shown a second embodiment, in which parts identical to those shown in Figs. 1 - 3, are defined by same reference numerals. Thus the outer pipe is defined by 10, the inner pipe by 12 and the transversely projecting material projections by 16a and 16b, the bolt shank 18 having a fixed head 20 and being provided with a loose tightening nut 22. In this embodiment each material projection 16, 16b has an insert, respectively 24a and 24b, arranged thereto, each formed with a through bore, respectively 26a and 26b, for passing the bolt shank 18. The projecting ends of these inserts 24a and 24b and possibly the end surfaces of the material projections 16a, 16b, facing opposite directions, serve as abutments for the bolt head 20 and the tightening nut 22. In the tightening, the material of the inserts are pressed into the inner pipe 12 , so that a more secure connection is created as a consequence of the pipe 12 being squeezed in the pipe portion 12 • . The pipe coupling/joint according to the third exemplary em- bodiment in Figs. 6 - 9 works approximately in the same way. Here, the material projections 16A, 16B are not drawn outwards into portions of triangular cross-sectional form, but, on the other hand, of a rectangular/U-shaped cross-section. Over the material projections 16A, 16B projecting trans- versely to the pipes 10, 12 are slid, Fig. 7, the slide-over elements 28a, 28b, shown in split sectional view in Fig. 6, with bores 30a, 30b for the passing of the bolt shank 18. Recessed surfaces 32a, 32b extending essentially parallel to the adjacent split 14 of the outer pipe 10, form abutments for the head 20 of the bolt and the nut 22. Each of the slide-over elements 28a, 28b are formed with a slot 34a, 34b defining a portion 36a and 36b, respectively, which is insertable into the through bore of an adjacent material pro- jection, and which occupies substantially the entire portion, while the rest of each slide-over element 28a, 28b remains outside the material projection 16A, 16B, respectively. Earlier the advantages of this embodiment by thin and thick pipe materials have been explained. In the tightening, the portions 36a, 36b are pressed into the inner pipe 12, so that a more secure connection is achieved as a consequence of the pipe 12 being squeezed in the pipe portion 12'. Figs. 8 and 9 show the rectangular/U-shaped cross section of the material projections 16A, 16B in the configuration used in the third embodiment. Figs. 6 - 9.

Claims: CLAIMS 1. A pipe coupling for joining pipe end portions, inserted telescopically one into the other, of two pipes (10, 12) or pipe bends, comprising an outer pipe end portion provided with at least one axial split (14) and formed to receive an inner concentric pipe end portion, in which there are formed, in the outer pipe end portion formed to grip around the inserted end portion of the inner pipe (12) , lug-shaped holders (16a, 16b; 16a', 16b'; 16A, 16B) from the material of the outer pipe and projecting transversely to the pipes (10, 12) on either side of said axial split (14) and being part of holder organs for bolt connections (18, 20, 22), the tightening of which results in a pressing of the end portion of the outer pipe around the inserted end portion of the inner pipe by the utilization of said split (14), cha r a cter iz ed in that said lug-shaped bolt holders, extending transversely to the pipes (10, 12) , take the form of drawn/pressed material projections (16a, 16b, 16a 1 , 16b 1 , 16A, 16B) having, in said transverse direction, outwards ta- pering, essentially trapezoid or U-shaped cross section, with the point/U-step located at the greatest radial distance from the longitudinal axis (A) of the outer pipe (10) . 2. A pipe coupling according to claim 1, character i z ed in that the material projections (16a, 16b; 16a 1 , 16b') are provided with bolt holes aligned in pairs, for a bolt connection, comprising a bolt shank (18) with fixed head (20) and loose, tightenable nut (22) , the longitudinal axis of this bolt connection extending parallel to a tangent to the outer surface of the outer pipe (10) in the area of an adjacent split (14) , the bolt shank (18) extending through said aligned bolt holes of the pair of material projections (16a, 16b; 16a', 16b'), while the bolt head (20) and the tightening nut (22) , in the tightened position of the bolt connection (18,20,22), bear supportingly against outer surfaces of a mutually dependent pair of material projections facing opposite directions. 3. A pipe coupling according to claim 1, character i z ed in that the material projections (16a, 16b; 16A, 16B) are provided with through slots aligned in pairs for the complete or partial reception of insertable reinforcing pieces (24a, 24b; 28a, 28b) which are formed with passages (26a, 26b; 30a, 30b) aligned in pairs for the reception of a bolt shank (18) . 4. A pipe coupling according to claim 3, charact er i z ed in that said reinforcing pieces (28a, 28b) have bearing surfaces (32a, 32b) which face opposite directions and which form, maybe together with the outer end surfaces of the material projections (16a, 16b; 16A, 16B) facing opposite directions, abutment and bearing surfaces for the bolt head (20) and the nut (22) in the tightened position of the bolt connection (18,20,22). 5. A pipe coupling according to claim 3, char acter i z ed in that said reinforcing pieces (28a, 28b) are comprised by bodies, each being formed with a particular attachment portion (36a, 36b) which is insertable into the through slot of the respective material projection (16A, 16B) , and that the attachment portions (36a, 36b) of one cooperating pair are facing each other by their free outer ends, so that they are held and are pressed into engagement with the slots of a pair of material projections (16A, 16B) by the tightening of the bolt connection (18,20,22).

Inventors: HELLAND INGOLF, HELLAND, INGOLF
Applicants: HELLAND INGOLF, HELLAND, INGOLF
Application year: 1998
Main classification: F16L21
IPC codes: F16L21