APPARATUS FOR WELDING TUBES

Abstract: The invention concerns an apparatus for welding tubes comprising a frame (8), a tube resting zone (2), clamp means (4) to block the tube (3) in the welding position, said clamp means (4) being comprised of two halves (4', 4'') partially surrounding the tube (3) and eventually provided with adapter means (7) for different diameters of the tube, the tube (3) of any dimension being supported with its welding surface (6) placed always at the same pre-established height, a welding mirror (10), provided with means for fixing an upper matrix and a lower matrix, and provided with support means (12, 13, 14, 15) to approach and to move away the tubes to be welded, allowing its displacement along the horizontal plane and along the vertical plane, with the possibility of combining the two motions to obtain a continuous adjustment on the three axis, with any orientation, clamp means (17) to support the tube to be welded, said clamp means being adaptable to any dimension of the tube to be welded, and being vertically slidable along said frame (8).

Description: APPARATUS FOR WELDING TUBES The present invention concerns an apparatus for welding tubes. More specifically, the invention concerns an apparatus allowing to carry out weldings between two plastic tubes, either to weld pipe fittings or to weld head tubes, substantially defect free, in such a way to guarantee optimum features of the same weld. The problem of welding plastic tubes, and particularly the welding of deviation pipe fittings on a main tube, independently from the dimensions, is very important and has practically unsolved, at least as to the obtainment of a welding having optimum features. In fact, on the market many apparatuses exist to carry out this kind of weldings, none of them being able to guarantee a welding without defects. In fact, in most cases, known apparatuses are realised in such a way to not induce deformations of the elements to be welded, or not to guarantee the respect of the proper positioning during the welding. Until a historical period, this kind of imprecision, that can partly be compensated by the skillness of the operator, even constituting a problem, was not deemed to be substantial, since the same weldings, particularly the weldings of the deviations, were intrinsically defective. In fact, before the filing of the Italian patent N° 1 ,231 ,685 on May, 18, 1989, assigned to the same applicant, deviation had a circular section, so that welding obtained were in any case defective. With the structure of the new pipe fittings, sold on the market by the same applicant, it has been possible to obtain structurally perfect weldings, but in this case apparatuses presently available on the market does not allow to exploit at best the features of the pipe fittings. In view of the above, the Applicant has realised an apparatus allowing to carry out any kind of welding, i.e. head, 90° or 45° weldings, having substantially perfect structural features. One object of the present invention is that of providing an apparatus having a constant height of the welding surface. Another object of the present invention is that of realising an apparatus allowing to carry out both deviation and head weldings. Still another object of the present invention is that of realising an apparatus allowing to carry out weldings in any position of the tube, without any obstacle by the same apparatus. It is therefore specific object of the present invention an apparatus for welding tubes comprising a frame, a tube resting zone, clamp means to block the tube in the welding position, said clamp means being comprised of two halves partially surrounding the tube and eventually provided with adapter means for different diameters of the tube, the tube of any dimension being supported with its welding surface placed always at the same pre-established height, a welding mirror, provided with means for fixing an upper matrix and a lower matrix, and provided with support means to approach and to move away the tubes to be welded, allowing its displacement along the horizontal plane and along the vertical plane, with the possibility of combining the two motions to obtain a continuous adjustment on the three axis, with any orientation, clamp means to support the tube to be welded, said clamp means being adaptable to any dimension of the tube to be welded, and being vertically slidable along said frame. Preferably, said frame is offset with respect to the tube on which the welding is carried out. According to a particularly preferred embodiment of the present invention, said clamp means are comprised of a pair of clamps, each one comprising two openable and closable halves to clamp the tube, said halves being comprised of different circle arches and coupling with the tube in such a way to close and upper portion of the half of the circumference. Always according to the invention, said adapting means are comprised of two halves, corresponding to the halves of said clamp means, and having a centre of the tube in a variable position, in such a way to keep the welding surface always at the same level. Still according to the invention, said means for fixing the upper and lower matrixes on said welding mirror can be provided with means for adjusting the position of the matrixes. Furthermore, according to the invention, said support means of the welding mirror can be comprised of a first pair of side horizontal guides, allowing the sliding of the mirror, with an independent positioning with respect to the horizontal plane, and a second pair of side vertical guides, allowing the sliding of the mirror, with an independent positioning with respect to the vertical plane. Further, according to the invention, said mirror can be provided with independent lateral counterweights, preferably having a variable weight. Still according to the invention, said clamp means can slide vertically, along at least one vertical guide, driven by a oleodynamic, pneumatic, hydropneumatic, etc, actuator. Furthermore, said sliding guides for the clamp means can be the same or different with respect to the side vertical sliding guides of the welding mirror. Preferably, said clamp means can be comprised of two clamps, movable along a horizontal plane, symmetrically with respect to the tube to be clamped, and shaped in such a way to adapt to different diameters of the tube. Further, adjustment means for the position of the same clamp after the clamping of the tube can be provided on said clamp means, said adjustment means being preferably comprised of elastic means provided with lever blocking means. Always according to the invention, a drilling machine can be provided to hole the welding zone after the completion of the lateral welding. According to the invention, said drilling machine and said clamp means can be provided on separated supports or on a rotatable support, in such a way to alternatively bring the two tools in an operative position. Contrast means can be further provided on said drilling machine to contrast the action of the drilling machine during the holing action. The present invention will be now described, for illustrative but not limitative purposes, according to its preferred embodiments, with particular reference to the figures of the enclosed drawings, wherein: Figure 1 is a lateral view of an embodiment of the apparatus according to the invention; figure 2 is a front view of the apparatus of figure 1 ; figure 3 shows a particular of the apparatus of figure 1 ; figure 4 is a lateral view of the particular of figure 3; and figure 5 schematically shows the motion system of the mirror of the apparatus according to the invention. Observing the figures of the enclosed drawings, it is shown an embodiment of the apparatus according to the invention. Apparatus 1 provides a support 2 for the main tube on which the welding must be carried out, realised in such a way to be able to freely rest the tube 3 without any limitation of the length of the same tube. As already mentioned, the apparatus 1 can also provide lateral supports to support tube 3. A clamp 4 is provided on said support 2 to clamp the tube, said clamp being comprised of two parts, respectively 4' and 4". As it can be particularly noted from figure 1 , clamp 4 is realised in a particular way to allow the clamping of the tube 4 without any deformation of the same. To this end, clamp 4 clamps the tube 3 beyond its half line, without closing it completely, with the two halves 4' and 4" of the clamp 4 not symmetric, even if the mobile part 4" is smaller than the fixed part 4'. A pin 5 is provided to fix the two parts 4' and 4" of the clamp 4. Tube 5 supported on the support 2 and clamped by the clamp 4 has a welding surface 6 positioned at a constant height. In fact, even if adapters 7 are used, said adapters being comprised of two parts 7' and 7", they are shaped in such a way that the tube 3 having a corresponding diameter has its welding surface always at the level indicated by the reference number 6. This solution allows to obtain a welding solution much more precise and constant, eliminating many of the defects of the known apparatuses. On the elements T and 7" of the adapters 7, means, not shown, are provided, e.g. comprised of grooves and pins, to fix them each other without any relevant motion during the clamping. On the main frame 8 of the apparatus according to the invention, two side vertical guides 9 are provided to vertically move, in an independent manner, the welding mirror 10 by slidable supports. In the solution suggested according to the present invention, frame 8 is offset with respect to the tube 3, thus completely freeing the working zone. Furthermore, mirror 10 (as it can be better noted from figure 5), is mounted on two horizontal axis 13, on which the supports 14 slide, for the independent motion along the horizontal plane of the mirror 10. Laterally with respect to the mirror, two independent counterweights (not shown) are provided, having a weight slightly bigger than the weight of the mirror 10 and of the upper and lower matrixes. As already mentioned, the two counterweights can have a variable weight, in function of the matrixes used. With this kind of support, it is possible to carry out any adjustment of the mirror 10, before beginning the welding, in order to obtain an optimum positioning of the elements to be welded. Matrixes (not shown) are mounted on the mirror 10, their position on the mirror being adjustable by the guides 15. Always on the frame 8, a group 16 is provided, slidable along the guides 9, said group 16 bridging to the clamp 17 (that can be particularly seen from figures 3 and 4) and the drilling machine 18. In fact, said group 18 can rotate about the pin 19 and slides by hydraulic actuators 24. Said clamp 17, see also figures 3 and 4, provides two lateral symmetric clamps 20, having a central groove 21 , to clamp the derivation tube to be welded, independently from the dimension of the same tube, slidable along the screw 22 and the guides 22'. In this way, a tightening is obtained without deforming the tube. Furthermore, said clamp 17 provides a further precision adjustment system comprising four springs, not shown, and a fixing lever 23, to be used after the clamping of the tube and its positioning on the matrix. Obviously, even if the solution shown in the figures provides drilling machine 18 and clamp 17 supported by a sole rotatable group, it is evident that they can be also provided in a different manner, without modifying the inventive concept. The drilling machine 18 can also provide elastic contrast means (not shown) to contrast its action during the perforation of the joint. Apparatus 1 according to the invention is structured in such a way to allow to freely carry out weldings with any orientation, without any obstacle. Furthermore, there is no limit to the length of the tube to be welded. When it is necessary to carry out a welding using the apparatus according to the invention, after having chosen the adapter suitable for the tube 3 on which the welding is carried out, the upper and lower matrixes are fixed on the mirror 10 with an eventual adjustment of their position by the guides 15, and it is fixed the tube to be welded in the clamp 17. Now, acting on the guides 12 and 14, the mirror is approached to the tube 3 to verify the proper coupling, and thus the same step is carried out approaching the clamp 17 to the upper matrix coupled with the mirror 10 and carrying out eventual further adjustments on the clamp 17 by the springs (not shown) and the lever 23. When the apparatus 1 according to the invention is started, the various elements are brought in the rest position, and the mirror is heated until reaching the suitable and necessary welding temperature. Now the mirror 10 is approached to the tube 3 until perfectly matching the lower matrix, acting of the adjustment systems of the same mirror 10. However, just in view of the presence of the counterweights, it is possible to approach the mirror 10 to the tube clamped by the clamp 17, and thus lower the clamp 17, and consequently the mirror 10 along with the lower matrix, to the tube 3, the motion shown in the figure allowing a almost perfect approaching. Then the clamp 17, bearing the tube to be welded, is approached to the upper matrix, and the it necessary to wait for the time needed to fuse the material comprising the two tubes. After this period, the mirror along the matrixes is withdrawn and the two tubes are coupled, eventually adjusting their position one with respect to the other. An absolutely symmetrical and without any displacement due to deformations of the two tubes and to movements of the two elements one with respect to the other, welding is obtained. The clamp 17 is then opened and withdrawn, and after the rotation of the group 16 about the pin 19, the perforation of the joint by the drilling machine 18 is carried out. The present invention has been described for illustrative but not limitative purposes, according to its preferred embodiments, but it is to be understood that modifications and/or changes can be introduced by those skilled in the art without departing from the relevant scope as defined in the enclosed claims.

Claims: CLAIMS 1. Apparatus for welding tubes, characterised in that it comprises a frame, a tube resting zone, clamp means to block the tube in the welding position, said clamp means being comprised of two halves partially surrounding the tube and eventually provided with adapter means for different diameters of the tube, the tube of any dimension being supported with its welding surface placed always at the same pre- established height, a welding mirror, provided with means for fixing an upper matrix and a lower matrix, and provided with support means to approach and to move away the tubes to be welded, allowing its displacement along the horizontal plane and along the vertical plane, with the possibility of combining the two motions to obtain a continuous adjustment on the three axis, with any orientation, clamp means to support the tube to be welded, said clamp means being adaptable to any dimension of the tube to be welded, and being vertically slidable along said frame. 2. Apparatus according to claim 1 , characterised in that said frame is offset with respect to the tube on which the welding is carried out. 3. Apparatus according to claim 1 or 2, characterised in that clamp means are comprised of a pair of clamps, each one comprising two openable and closable halves to clamp the tube, said halves being comprised of different circle arches and coupling with the tube in such a way to close and upper portion of the half of the circumference. 4. Apparatus according to one of the preceding claims, characterised in that said adapting means are comprised of two halves, corresponding to the halves of said clamp means, and having a centre of the tube in a variable position, in such a way to keep the welding surface always at the same level. 5. Apparatus according to one of the preceding claims, characterised in that said means for fixing the upper and lower matrixes on said welding mirror are provided with means for adjusting the position of the matrixes. 6. Apparatus according to one of the preceding claims, characterised in that said support means of the welding mirror are comprised of a first pair of side horizontal guides, allowing the sliding of the mirror, with an independent positioning with respect to the horizontal plane, and a second pair of side vertical guides, allowing the sliding of the mirror, with an independent positioning with respect to the vertical plane. 7. Apparatus according to one of the preceding claims, characterised in that said mirror is provided with independent lateral counterweights. 8. Apparatus according to claim 7, characterised in that said counterweights have a variable weight. 9. Apparatus according to one of the preceding claims, characterised in that said clamp means slide vertically, along at least one vertical guide, driven by a oleodynamic, pneumatic, hydropneumatic, etc, actuator. 10. Apparatus according to one of the preceding claims, characterised in that said sliding guides for the clamp means are the same or different with respect to the side vertical sliding guides of the welding mirror. 11. Apparatus according to one of the preceding claims, characterised in that said clamp means are comprised of two clamps, movable along a horizontal plane, symmetrically with respect to the tube to be clamped, and shaped in such a way to adapt to different diameters of the tube. 12. Apparatus according to one of the preceding claims, characterised in that adjustment means for the position of the same clamp after the clamping of the tube areprovided on said clamp means, said adjustment means being preferably comprised of elastic means provided with lever blocking means. 13. Apparatus according to one of the preceding claims, characterised in that a drilling machine is provided to hole the welding zone after the completion of the lateral welding. 14. Apparatus according to one of the preceding claims, characterised in that said drilling machine and said clamp means are provided on separated supports or on a rotatable support, in such a way to alternatively bring the two tools in an operative position. 15. Apparatus according to one of the preceding claims, characterised in that contrast means are further provided on said drilling machine to contrast the action of the drilling machine during the holing action. 16. Apparatus for welding tubes according to each one of the preceding claims, substantially as illustrated and described.

Inventors: MEIRANA GIOVANNI, MEIRANA, GIOVANNI
Applicants: M K M S R L, MEIRANA GIOVANNI, M.K.M. S.R.L., MEIRANA, GIOVANNI
Application year: 1999
Main classification: B29C65
IPC codes: B29C65