PROCESS AND APPARATUS FOR THE COLD SHAPING OF PIPES OR FITTINGS, AND ARTICLES THUS OBTAINED

Abstract: A pipe or fitting tubular section (17) is at first deformed so as to obtain at least a radial wall, substantially perpendicular to the pipe axis, and having, as regards the thickness, such a height that its buckling limit load is inferior to its combined bending and compressive limit load; then said pipe is deformed by substantially radial forces acting on a zone adjacent to said radial wall which acts as a support. The radial wall can be supported at its internal base. The radial wall (22, 22a) can be formed by operating shaped radial inserts (40) on the pipe wall or by axially operating one against other two dies that leave the pipe free at a desired point thus creating a collar. A subsequent cold-working can be carried out both by radial inserts and by putting in contact a pipe portion adjacent to said radial wall with a fixed surface which shapes said portion. An axial shaping of the radial wall can be provided axially operating with dies.

Description: "PROCESS AMD APPARATUS FOR THE COLD SHAPING OF PIPES OR FITTINGS, AND ARTICLES THUS OBTAINED" The present invention refers to a process and apparatus for the cold shaping or cold forming of pipes or metallic pipe fittings, as well as to the articles thus obtained. These shapes are normally obtained by casting or through a mechanical process, thus they are expensive. The attempt made of producing these articles in plastic has resulted in pieces having a mechanical resistance definitely unsuitable for the great majority of the most common uses. The aim of the present invention is to produce pipes or metallic pipe-fittings of various shapes which are much more economical 5 , than the prior art ones, while still maintening their sturdiness unaltere . The above mentioned aim has been achieved by foreseeing a process according to which at least substantially radial one wall is firstly produced, which is perpendicular to the pipe or pipe-fitt- 101. ing-axis and has - as regards its thickness - such a height that its buckling limit load is lower than its combined bending and compressive limit stress; said pipe or pipe-fitting is then cold-worked by having substantially radial forces acting on an area adjacent to said radial supporting wall. Preferably the 15. radial wall is in turn supported at its internal base, for instance by a plug. Said radial wall can be formed by having shaped radial die slides or inserts act on the pipe or pipe-fitting wall, or by axially operating one against the other two dies that leave the pipe free 20. at a desired zone thus creating a collar. The subsequent cold processing or working can be carried out both by operating radial die slides or inserts or by letting a pipe portion adjacent to said radial wall contact a fixed surface which shapes said pipe portion. 25. An axial shaping of the radial wall can also be foreseen, obtained with dies operating axially. It must be noted that the steps of forming at least a radial wall and of subsequent shaping the pipe or pipe-fitting can be carried out also in a single operation. 5. The obtained articles are preferably, but not limitedly: pipes or pipe-fittings having a same diameter at both ends or different diameters and with a polygonal or circular collar; pipes or pipe-fittings with ring or saw-toothed ends, preferably with- longitudinally ribs. Possibly these hose fittings can have 10. circular collars capable of sealing up with conical or flat coupling surfaces. The process essential steps, the various apparatuses according to preferred but not limiting embodiments, and the articles thus obtained, are illustrated in the enclosed drawings, wherein: 15. Fig. 1 is a plan view of two successive steps in the shaping of a pipe or pipe-fitting; Fig. 2 shows the section along line 2-2 of Fig. 1; Fig. 3 shows the first shaping step of a pipe which will have ends of different diameters; 20. Fig. 4 shows a forming phase of two adjacent radial walls on the pipe illustrated in Fig. 3; " Fig. 5 shows the shaping phase of the connecting zone between the radial walls formed in the phase illustrated in Fig. 4; Fig. 6 shows a part-sectional view of two successive working 25. steps carried out with an equipment allowing the taking of these steps, as well as of an axial shaping, in a single operation; Figs, 7 and 8 show in a part-sectional side view two examples of the obtained pipe-fittings; Fig. 9 shows a bottom perspective view of a pipe-fitting obtained 5. by using the equipment of Fig. 6; Fig- 1Q shows section 10-10 of the equipment of Fig. 12; Fig.. 11 shows section 11-11 of Fig. 13; Figures 12 to 15 show successive working steps of a hose-fitting; Fig. 16 shows an enlarged detail of fig. 15; 10. Fig. 17 shows an enlarged detail of a further type of shaping; Figures 18 and 19 show enlarged pipe-sections with two differently shaped collars; Fig. 20 shows a greatly enlarged detail of Fig. 16; Figures 21 to 23 are part-sectional side views of fittings with- 15... the hose-fitting area obtained through the working process shown in figures 12 to 15. Figures 1 and 2 show the working phases of a pipe 17 section. This pipe is inserted in the dies 20 and 20a provided with abutments 13 and is compressed axially obtaining first, in a known way, through 20.. cone 29, the enlargement of one of its portions, then the forming of radial walls 22 and 22a. These latter are then shaped by inserts 40 acting radially to the pipe section 17. During these working phases, the pipe and particularly the internal base of each radial wall 22 and 22a is supported by a support 30 inside 25. the pipe, preferably a plug. This internal support 30 is provided with at least a cone 29 which produces the shaping of the pipe and supports the internal base of the radial walls 22 and 22a. Figures 3, 4 and 5 show more in detail the above mentioned working phases; as shown in Fig. 3 a portion of pipe 17 is first enlarged, then continuing the compression by moving the dies 20 and 20a the radial walls 22 and 22a are formed (Fig. 4) . During this phase the 5 # approach of the two dies 20 and 20a is carried out, which are drawn near until the distance between the extreme ends 21 of the dies is equal to twice the thickness of the pipe to be shaped. Fig. 5 shows the shaping of area 10 connecting the radial walls 22 and 22a. In this phase, while the insert 40 presses on the radial 10. wall, the two dies 20 and 20a are left free to move away until the distance between the extreme sides 21 is equal to the thickness required in collar 11. Consequently, the inserts 40 have front sides 40a having a width equal to the collar thickness. When the ring inscribed to the polygonal collar is sensibly bigger 15. than the contiguous cylindrical zone, it is possible to carry out the various phases in a single operation. ns shown in fig. β, in this case the inserts are made integral to form a fixed shaped body 41. The dies 25 and 25a that, in reason of the above mentioned condition, have a sufficient thickness, 20. axially press the pipe portion 33 thus forming two opposite radial walls 22 that in this case are identical; their external connecting zone 10 adheres to the fixed shaped body 41 creating a polygonal collar 12. In particular, to obtain this collar, the dies 25 and 25a have polygonal peripheral surfaces 24 and opposing 25. front surfaces 26 shaped in such a way that the distance between the two dies 25 and 25a in correspondence of the polygon edges is less than the distance existing between the dies in correspondence of the center-lines of the polygon sides. Examples of the obtained articles are shown in figs. 7, 8 and 9. Fig. 7 shows a pipe-fitting 18 having a polygonal collar 11 and two portions having different diameter; this pipe-fitting has been 5. obtained with the equipment shown in figures 1 to 5. Fig. 8 shows a pipe-fitting 19 similar to the one in fig. 7, but having equal diameter at both ends. Fig. 9 shows a pipe-fitting 14 having a polygonal collar 12 manufactured with the fixture of fig. 6 and having ends of equal diameter. 10. Figures 10 to 15 refer to a further working process capable of producing other types of collars, for instance to obtain pipes or hose-fittings. This further working process foresees the formation of a first 15. radial wall, which is aimed to support the subsequent step that is the forming, at a suitable distance, of a second radial wall, which itself supports the formation of a further radial wall and so on. In Fig. 10 is visible a pipe or pipe-fitting 27 inside the fixture 20. or apparatus made up of inserts 36 and of the internal support 30 which is preferably a plug. This internal support 30 is endowed with abutment 29a. The inserts have preferably a peripheral chamfer 28 liable to be partially or totally filled by the material making up the pipe, so as to form longitudinally ribbed 25. portions 43 running along the pipe 27 body. In Fig. 11 said ribs 43 are shown in section. Fig. 12 shows a pipe section 27 for hose-fitting having a smooth hose-fitting end, inserted on an internal support 30 having an abutment 29a. In correspondence of this abutment 29a, but at a distance D substantially equal to the pipe thickness on which the fitting is carried out, a series of inserts 36 is placed radially 5. to the X-X axis of the pipe section 27. The inserts 36 have in fact a step 35 placed in correspondence of abutment 29a, taking account of portion D equal to the pipe thickness. The inserts 36 by closing as shown in figures 11 and 13 form the radial wall 15 and the bent tooth 16. The inserts 36 are opened, the pipe 27 is 10. drawn out from the internal support 30 for a length P equal to the pitch of the hose-bearing collars. At this point, the shaping of the next radial wall starts, made possible by the presence of the previous radial wall which supports the subsequent shaping phase (Fig. 15) . The inserts 36 are opened again, the pipe is drawn out 15. and so on until all the desired collars are produced. Preferably, as shown in Fig. 13, 14 and 15, longitudinal ribs 43 are shaped on the hose-fitting pipe, the ribs being such to prevent during the use the reciprocal rotation of the plastic or rubber pipe as regards to the fitting. 20. Fig. 16 illustrates an enlarged detail of Fig. 15 showing an insert 36 apt to shape the saw-tooth hose-fitting area. Fig. 17 shows a particular configuration of the ring-type hose-fitting zone obtained by operating a further type of inserts 44 suitably shaped and by extracting the fitting, after each 25. forming of the radial wall 15a. The inserts 44 have a front parallel to the pipe axis, therefore the tooth 16a, which will be formed between two subsequent radial walls, will be parallel to - 8 - the pipe axis . Figures 18 and 19 show the sections of collars of different form, that is having the hose-fitting zone respectively saw-tooth or ring shaped. ^ Fig. 20 shows, greatly enlarged, a detail of Fig. 16; it evidentiates the radial wall 15 joined to the bent tooth 16. The abutment 29a of the plug 30 is preferably not perpendicular to the X-X axis of the pipe or pipe-fitting, but it is slanted with respect to it of an angle o slightly bigger than 90°. Also the 10. step 35 of the inserts 36 is preferably slanted to the X-X axis of an angle preferably equal to ζ ^ . The inserts movement direction is slanted of an angle / to the axis of pipe X-X. The angle is preferably inferior to 90°. The aim of these e- ζ^ and /S angles which differ of 90° is to obtain the edge 48 more accentuated 15 ^ (reduced external bending radius r) having pressed the material between the surface 35 of the insert 36 and the ledge 29a of the plug 30. According to the height of the radial wall 15 and its thickness, the angle o . can vary from 90° to 110° and the angle / > from 90° to 60°. 20. Figures 21, 22 and 23 illustrate examples of hose-fittings 45, 46 and 47 obtained with the process and the apparatus above described.

Claims: C A I M S 1. A process for cold forming various shapes, different from simple collars, on pipes or pipe-fittings, with walls having substantially uniform thickness and approximately equal to the one of the original pipe, characterized in that at first at last one 5. substantially radial wall (22, 22a, 15) is fomed, that is perpendicular to the axis (X-X) of the pipe or pipe-fitting, then by the action of substantially radial forces, zones near the radial wall are deformed so as to obtain desired shapes, said radial wallacting as only means of contrast to these forces, being the 10. ratio height/thickness such that its buckling limit load is lower than its combined bending and compressive stress, and said wall being internally supported but with one side free at least to bend. 2. A process as in claim 1, characterized in that the forming phases of at least a radial wall (22, 22a, 15) and of the 15. subsequent pipe or pipe-fitting, are carried out during a single operation. 3. A process as in claims 1 and 2, characterized in that during the subsequent deformation phase of the pipe or pipe-fitt¬ ing, the radial wall (22, 22a, 15) created during the previous phase is free to axially move. 5. 4. An apparatus for cold forming various shapes on pipes and pipe-fittings, characterized in that it is made up of means capable of forming at least a radial wall (22, 22a, 15) on the pipe or pipe-fitting, of a shaping member (40, 41, 36, 44) which acts in succession with previous means, in a substantially radial direction 10. near the area in which said lateral wall (22, 22a, 15) has been made, of an internal support (30) , for instance a plug, which can be inserted into the pipe or pipe-fitting to be shaped and support from the inside the base of the radial wall (22, 22a, 15) . 5. An apparatus as in claim 4, characterized in that the 15. shaping member is made up of a series of inserts (40, 36, 44) separated and movable on a radial plane towards and away from the pipe or pipe-fitting, so as to produce either polygonal collars (11) or saw-tooth hose fittings (16, 16a). 6. An apparatus according to claim 4, characterized in that 20. the shaping member is a fixed wall (41) , 7. An apparatus as in any of the claims from 4 to 6, characterized in that the means apt to form a radial wall (22, 22a, 15) are dies (20 and 20a, 25 and 25a) provided with an abutment (13) for supporting the pipe or pipe-fitting ends. 25. 8. An apparatus as in claim 7, characterized in that the dies (25, 25a) have polygonal external surfaces (24) and opposing front surfaces (26), shaped in correspondence of each side of the polygon which can come closer to each other in correspondence of the polygon's edge and are further away in correspondence of the center 5- line of each side. 9. An apparatus as in claims 4 and 5, characterized in that the inserts (36, 44) have a peripheral chamfer (28) capable of producing longitudinal ribs (43) on pipes or hose-fittings. 10. An apparatus as in claims 4 and 5, characterized in that 1°- the inserts (36, 44) have a movement slanted of 3 (inferior to 90°) with reference to the pipe axis (X-X) . 11. An apparatus as in claims 4 and 10, characterized in that the plug (30) is provided with an abutment (29a) slanted of an angle { <. ) comprised between 90° and 110° with reference to the ^5- x-x axis of the pipe or pipe-fitting. 12. A pipe or metallic pipe-fitting obtained with the process described in one of the claims 1 to 3, characterized in having radial walls (22, 22a, 15) externally adjacent to a polygonal wall (11, 12) which is coaxial to the pipe or pipe-fitting, and that all 20• walls have a substantially uniform thickness. 13. A pipe or metallic pipe-fitting, obtained according to the process as in claims from 1 to 3, characterized in that the radial walls (15) form a hose-fitting and that peripheral ribs (43) are foreseen on these radial walls which extend axially, all the walls " • maintaining a substantially uniform thickness .

Inventors: ARCHI AUGUSTO, SEBASTIANI ENRICO, ARCHI, AUGUSTO, SEBASTIANI, ENRICO
Applicants: SEBASTIANI ENRICO, SEBASTIANI, ENRICO
Application year: 1987
Main classification: B21D17
IPC codes: B21D17, B21D53