PROCESS AND APPARATUS FOR WELDING AND OTHER HEAT TREATMENTS

Abstract: Method and apparatus for welding a plurality of parallel continuous seams (34) on bellows (10) which comprise the steps of defining a welding station (100, 200) including a laser beam (501) or electron beam (700) welding source and a working plane (505) spaced from the welding source (500, 700) and wherein the working plane (505) is perpendicular and intersects a plane containing the radiation welding source (501, 700). The welding source (501, 700) spans a welding zone defined at the intersection of the working plane (505) and the plane contains the welding source. The seams (34) are maintained to be welded spaced apart and parallel and moving at least one of the welding stations and the several workpieces, in unison, relative to one another such that the seams (34) to be welded pass through the welding zone whereby welded seams are formed continuously on the bellows.

Description: PROCESS AND APPARATUS FOR WELDING AND OTHER HEAT TREATMENTS Technical Field The present invention relates to welding, heat treating and surface machining techniques, par¬ ticularly to improvements in welding simultaneously and at high speed a plurality of annular plates for a large diameter bellows in addition to improvements in laser beam delivery systems. Background Art It is well known that the welding of bellows or expandable bladders (shown in U. S. Patent 4,102,438) by electron beam or laser welding techniques has a high cost and is a time consuming process impli- eating the repetitive welding of the inside-diameter edges and outside-diameter edges of each annular sheet forming the bellows. It is also recognized that a major problem is the welding of relatively large diameter bellows (over 300 mm in diameter), particularly produced from relatively thin material (± 0.13 mm). The deformation produced by the thermal expansion from the repetitive welding generates stress at the welding seam which makes it very difficult, if not impossible, to produce fluid-tight bellows on a large scale, without suffering a high rate of rejects. It is also well known that the tracking of a seam to be welded, using a focused circular beam cen¬ tered on the seam, by electron scanning or other methods, reduces the linear welding speed in view of the reaction time delay involved, and that such track¬ ing is limited to one seam at a time. It is also well known that it is relatively easy to scan and control the focus of an electron beam from an electron beam welder at high speed (measured in KHZ) since the beam is deflected and focused electro- magnetically when used principally for heat treating or surface machining. However, with laser equipment, the scanning and focusing of a laser beam is done mechani¬ cally through mirrors or lens, thus limiting the speed and precision thereof. Great strides were made in improving surface heat treating or machining with the use of electron beam high speed scanning. However, the high cost, complexity and the negative environmental impact of electron beam equipment have limited the use of this technique. Another factor which has a serious cost impact in laser surface machining, glazing, cladding, alloying, and hardening, is the limited area covered by the laser focal beam at the working surface, thus requiring a large amount of beam scanning or work piece movements, to cover a working area larger than the focal beam diameter. Disclosure of the Invention It is an aim of the present invention to provide an electron beam welding technique to weld simultaneously a plurality of seams. It is a further aim of the present invention to provide a laser welding technique to weld simultane¬ ously a plurality of seams. It is a further aim of the present invention to provide a holding and a separating means to provide the welding of a plurality of seams simultaneously. It is a further aim of the present invention to provide a holding means to provide the welding of a plurality of seams formed from annular sheets for a bellows, simultaneously. It is a further aim of the present invention to provide an improved laser beam delivery system means to provide, in the working plane, an oblong laser beam pattern in order to produce an improved tracking speed for a welded seam, to allow the simultaneous welding of a plurality of seams, to improve laser surface machin- ing, glazing, cladding, alloying, hardening and heat treating technique, that is, to assume the features of an electron beam welder without the high cost and negative environmental impact involved in electron beam welding, heat treating or surface machining techniques. It is a further aim of the present invention to provide an improved laser beam delivery system to provide, in the working plane, different geometrical shapes, such as an annular or "S" shape in order to produce an effect similar to a spot weld or to weld relatively small pieces instantaneously without having to make linear movements, thus reducing the negative impacts created by thermal distortion and the cost involved. It is a further aim of the present invention to provide an improved laser beam delivery system to provide, in the working plane, a plurality of oblong beam patterns in order to weld simultaneously a plurality of spaced-apart seams and to heat treat or surface machine a plurality of areas simultaneously from a workpiece or different workpieces. A heat treatment, surface machining, cutting or welding system in accordance with the present inven¬ tion utilizes at least a laser beam, wherein workpieces to be heat treated, surface machined, cut or welded are placed in a working plane, within the focal depth of the laser beam, and an optical element interrupts the laser beam to project the beam with a predetermined geometric pattern other than a circular spot at the working plane. More specifically, an application zone having a width to include the area of heat treatment, surface machining, or a weld, is determined, and the geometric beam pattern is determined which at least spans the application zone. A method of welding a plurality of parallel continuous seams on workpieces in accordance with the present invention comprises the steps of defining a welding station including a radiation welding source and a working plane spaced from the radiation welding source and wherein the working plane intersects a plane containing the radiation welding source, the radiation welding source spanning a welding zone defined within the focal depth at the intersection of the working plane and the plane containing the welding source, maintaining the seams to be welded spaced apart and parallel and moving at least one of the welding stations and the several workpieces, in unison, relative to one another such that the seams to be welded pass through the welding zone whereby welded seams are formed continuously on the workpieces. More specifically, in one embodiment the radiation welding source is an electron beam generator adapted to scan the welding zone. In a still more specific embodiment, the method includes a laser generator as the radiation welding source which delivers a laser beam which forms a focal pattern, by means of optical elements, which at least spans the welding zone. The term "optical elements", when utilized in this specification, will include both transmission and reflective elements. An apparatus for heat treating, surface machining, or welding workpieces according to the pre¬ sent invention includes at least a laser beam gener¬ ating means, means defining a working plane in which workpieces are placed, and at least an optical element located in the path of the laser beam such that a geometric pattern other than a circular spot is pro¬ vided at the working plane. The optical element may be a diffractive optical element capable of dividing the laser beam into a plurality of beams forming overlapped or spaced-apart geometric patterns at the working plane. It is also contemplated to use two or more laser sources and to transmit the laser beams through the optical element or optical elements arranged in series in the path to provide a plurality of overlapped or spaced-apart geometric patterns on the working plane. An apparatus for welding a plurality of parallel continuous seams to join several workpieces in pairs includes jig means for maintaining the workpieces and for holding the workpieces and the seams to be welded in spaced-apart and parallel relationship, welding means including a radiation welding source and a working plane spaced apart from the radiation welding source, means mounting the welding source in a plane intersecting the working plane, means associated with the welding station such that the welding source can span a welding zone including the intersection of the working plane and the plane containing the welding source, means for moving one of the welding station and the jig such that the seams to be welded pass continuously through the welding zone whereby welded seams are formed simultaneously on the workpieces. The laser beam can be used in the context of this invention to treat workpieces besides welding. For instance, by increasing the energy of the laser beam or beams at the working plane, the workpieces may be cut. The workpieces, f desired, may be subjected to surface machining by this process, or the workpiece, especially if it is a metal, may be subjected to heat treatment. What is common in each situation is that the state of the material of the workpiece has been altered at least partially by thermal energy. For the purpose of this patent application, the phrase "for partially altering the state of the composition of a workpiece by thermal energy" will include cutting, welding, surface machin¬ ing, heat treating, surface glazing, cladding, alloying and hardening.. It is furthermore contemplated that a wide and narrow laser beam reduces the rippling effect during surface treatment. Thus the rate of cooling of the metal is increased when a narrow beam (that is narrow in the longitudinal sense and wide in the trans¬ verse direction relative to the path of treatment) passes off the surface, since the cooling of the metal is more rapid then with a conventional large beam. The narrow beam is believed to penetrate the metal more deeply in order to improve transformation hardening. When an "oblong" beam is referred to in this specifica¬ tion the narrow beam is included. Brief Description of the Drawings Having thus generally described the nature of the invention, reference will now be made to the accompanying drawings, showing by way of illustration, preferred embodiments thereof, and in which: Fig. 1 is a perspective view, partly in cross-section, showing a typical annular expanded bladder or bellows; Fig. 2 is a fragmentary axial cross-section taken through a laser sub-assembly welding jig for welding the inside diameter of the outer concentric stage of annular plates; Fig. 3 is a fragmentary axial cross-section taken through a laser sub-assembly welding jig for welding the outside diameter of the inner concentric stage of annular plates; Fig. 4 is a fragmentary axial cross-section taken through a laser assembly welding jig for welding the outside diameter of the outer concentric stage of annular plates and end plates forming the bellows; Fig. 5 is a fragmentary axial cross-section taken through a laser assembly welding jig for welding the inside diameter of the inner concentric stage of annular plates and end plates forming the bellows; Fig. 6 is a fragmentary axial cross-section taken through the electron beam welding jig for welding the inside diameter of the outer concentric stage of the annular plates: Fig. 7 is a fragmentary axial cross-section taken through an electron beam sub-assembly welding jig for welding the outside diameter of an inner stage of annular plates; Fig. 8 is an enlarged fragmentary perspec- tive view of a detail of the welding jig; Fig. 9 is an enlarged exploded fragmentary perspective view of a detail of the welding jig; Fig. 10a is an enlarged fragmentary cross- section taken through a seam before welding; Fig. 10b is an enlarged fragmentary cross- section taken through a welded seam; Fig. 11 is an enlarged fragmentary per¬ spective view of a detail of the welding jig; Fig. 12a is a schematic view of a laser beam delivery system to produce an oblong beam pattern; Fig. 12b is another schematic view of a laser beam delivery system to produce an oblong beam pattern; Figs. 13a, 13b, 13c, 13d, 13e, 13f, and 13g are schematic views of laser beam delivery systems to produce oblong beam patterns or other geometric patterns using a beam divider; Figs. 14a and 14b are schematic views of laser beam delivery systems utilizing a plurality of laser sources; Fig. 15 is a schematic view of a laser beam delivery system utilizing a plurality of laser sources and fiber optics; and Fig. 16 is an enlarged fragmentary view of a detail of Fig. 15. Mode For Carrying Out The Invention Referring to Fig. 12a herein, laser beam 501 is transformed by means of a first mirror or lens 502 to an oblong beam 503. Oblong beam 503 is then focused transversally to longitudinal axis 503a by means of a second mirror or lens 504 to produce a generally oblong shaped beam 505 in the working plane. This oblong focal beam 505 is particularly useful to simultaneously fusion weld a plurality of seams, or to track and fusion-weld a seam at high speed. Beam 501 may be transformed in one step to an oblong focal beam 505 by means of a mirror or lens 502a, as shown in Fig. 12b. The advantage of using a plurality of lens or mirrors or a combination of both, as shown in Fig. 12a, is that the longitudinal dimension of axis 503a of oblong focal beam 505 may be calibrated to different sizes by varying the distance 504a between the lens or mirrors with an adjusting means. In a second alternative embodiment in a laser beam delivery system, referring to Fig. 13a, beam 501 is divided by means of a beam divider 506 to a plurality of circular divided beams 507, generally overlapped, which are then focused transversally to longitudinal axis 507a by means of a focal mirror or lens 508 to produce at least a generally oblong focal beam 509. The beam divider may be a diffractive opti¬ cal element, such as developed by the National Optics Institute of Sainte-Foy, Quebec, Canada, and Gentec, also of Sainte-Foy, Quebec, Canada. These elements may be obtained from Gentec. The plurality of circular divided beams 507 may be parallel, convergent or divergent. The longitu¬ dinal dimension of axis 507a of focal beam 509 may be calibrated to different sizes, when using a convergent or divergent beam divider, by varying the distance 506a between the beam divider 506 and the focal mirror or lens 508 with an adjusting means. When using a parallel beam divider, the distance 506a between beam divider 506 and focal mirror or lens 508 may be changed without affecting the focal beam 509. This is particularly use- ful when a telescopic beam delivery system is used. Referring to Fig. 13b, a plurality of focal oblong beams 509a may be produced by spacing apart the cir¬ cular divided beams 507 and then by focusing them to simultaneously perform a plurality of functions. As can be seen, the beams are divergent. Referring to Fig. 13c, it has also been contemplated to arrange the circular divided beams 507 such that shapes other than oblong may be produced in the working plane, such as an "S" shape, oval or a ring. A ring pattern 509b is particularly useful for producing the equivalent of a spot weld without having the negative impacts of the undercut produced by elec¬ trodes. Also, instantaneous welding or brazing of rela¬ tively small circular pieces can be accomplished with- out having to do circular movements, thus eliminating thermal distortion, particularly critical in relatively thin material, and reducing the cost involved in machinery. Figs. 13e and 13f show other examples including a pair of annular beams produced in Fig. 13e with a diffractive optical element. Fig. 13f shows a single optical element to form an annular beam and to size it at the working plane. In a third embodiment of a laser beam de- livery system, referring to Fig. 13d, beam 501 is transformed by means of a lens or mirror 510 to a pri¬ mary oblong beam 511 which is then divided by means of a beam divider 512 to a plurality of secondary oblong beams 513, generally lined up, which are then focused transversally to longitudinal axis 513a by means of lens or mirror 514 to produce at least a wide, gener¬ ally oblong, focal beam 515 or a plurality of generally oblong focal beams 515. The plurality of secondary oblong beams 513 may be parallel, convergent or diver¬ gent. The longitudinal dimension of axis 513a of focal beam 515 may be calibrated to different sizes, when using convergent or divergent beam dividers, by varying the distance 512a between the beam divider 512 and the focal mirror or lens 514. When using a parallel beam divider, the distance 512a, between the beam divider 512 and the focal mirror or lens 514, may be changed without affecting the focal beam 515. Referring to Figs. 14a and 14b, there are shown two embodiments of the use of three laser sources, each with laser beams 601, 602, and 603. The laser beams are directed to the optical element 606 in both cases. The optical element 606 may be a diftrac¬ tive optical element. The optical element 606, in the case of Fig. 14a, directs the beams to cover a wider span with roughly the same density while providing an oblong pattern. It has been found that in using a sin- gle laser source with a single laser beam, the density of the energy towards the end of the major axis of the oblong pattern at the working plane may be diminished compared to the density in the central portion thereof. By selecting a suitable optical element, in this case a diffractive element, the distribution of the energy density can be controlled over the span area. For instance, by providing a greater overlap of the beams towards the ends of the major axis of an oblong pattern, the difference in incidence angle may be com- pensated therefor. In Fig. 14b, the three laser beams are transmitted by the diffractive optical element 606 to extend over the same span area in order to increase the density of the laser in the area beam span. The provision of at least three laser beams from three different laser sources allows a more even distribution of the energy in the span and allows a wider span. It is anticipated that the preferred laser source would be an Nd:Yag laser for these types of applications. Referring now to Figs. 15 and 16, a plu- rality of laser sources, such as Yag lasers, are repre¬ sented by the three laser beams 701, 702, and 703, which are transmitted through the diffractive ele¬ ment 706. The transmission between the diffractive optical element 706 and the delivery optical ele- ment 708 is done through fiber optics 707 where the three beams are transmitted. As shown in Figs. 15 and 16, the beams 707 transmitted by diffractive ele¬ ment 706 are focused at a lens 711 which transmits the laser beams through a fiber optics element represented schematically at 712. The beams then pass through opti¬ cal element 708 which will then focalize the beams. Reference is made to fiber optics delivery of laser beams as supplied by Rofin Sinar of Plymouth, MI, U.S.A. It is also contemplated that the three laser sources could operate alternately in pulses so that each beam is transmitted in successive pulses and thus increase the average energy output. As is well known, a higher energy laser beam can be obtained by pulsing the laser beam generation to produce higher energy peaks. By properly sequencing the plurality of laser generators aimed at the diffractive optical element as shown in Figs. 14a, 14b, 15 and 16, an almost constant average greater energy density can be produced for welding, cutting, surface machining or thermal treatment of the workpieces. Reference is made to work done by Gentec in terms of laser beam monitoring. [Laser Pulse Analyzer (LPA-1)]. The embodiments shown in Figs. 14a, 14b, 15 and 16, for instance, is a way of obtaining a more powerful laser projection. Reference will now be made to embodiments in a technique to weld simultaneously a plurality of seams particularly applied to the welding of annular bellows which are more complex to produce than linear seam welds. Such a bellows may be utilized as a bladder in U. S. Patent 4,102,438. Referring to Fig. 1, an annular bellows 10 includes annular end plates 12 and 14, annular outer concentric stage 16, and annular internal concentric stage 18. Each stage 16 and 18 is made up of an ac¬ cordion arrangement of annular sheets or plates 19. Alternate inner and outer diameter welded seams in each stage and with the end plates 12 and 14 complete the bellows. A fluid inlet 28 is used when the annular bellows 10 performs as an expandable bladder. The outside diameters of the external stage 16 and end plates 12 and 14 are welded at seams 24. The inside diameters of internal stage 18 and end plates 12 and 14 are welded at seams 26. The inside diameters of the external stage 16 are welded at seams 20. The out¬ side diameters of the internal stage 18 are welded at seams 22. In the present embodiments, bellows 10 or a plurality of bellows 10 are welded in four phases as follows: PHASE I: Referring to Figs. 1, 2 and 6, the external stage 16 is welded by pairs at their inside diameters 20 to form sub-assembly 16A at a sub-assembly welding station 100 as will be described later. Fig. 2 refers to a laser welding technique, and Fig. 6 refers to an electron beam welding technique. PHASE II: Referring to Figs. 1, 3, and 7, the internal stages 18 are welded by pairs at their outside diameter 22 to form sub-assembly 18A, at a sub- assembly welding station 200 as will be described later. Fig. 3 refers to a laser welding technique, and Fig. 7 refers to an electron beam welding technique. PHASE III: Referring to Fig. 1 and Fig. 4, end plate 12, external stage sub-assembly 16A from Phase I, internal stage sub-assembly 18A from Phase II, and end plate 14 are assembled at an assembly welding station 300 and outside diameters of end plate 12, external stage 16 and end plate 14 are welded to their respective adjacent counterparts at seams 24 to form a pre-welded bellows 10a as will be described later. PHASE IV: Referring to Figs. 1 and 5, inside diameters of end plate 12, internal stage 18 and end plate 14 of the pre-welded bellows 10a are welded at seams 26 to their respective adjacent counterparts to form bellows 10 at an assembly welding station 400 as will be described later. PHASE I Referring to Figs. 1 and 2, sub-assembly welding station 100 includes an annular ring 140 jour- naled to a structure 170 for rotation therein, a base 106, a column 120, a clamping ring 160, and a comb assembly 600. Structure 170 is mounted perpendicular to base 106 and provided with an internal annular wall 172 which is defined on each side by annular abutment walls 174. The internal radial dimension of annular wall 172 and the axial dimension between the abutment wall 174 are such as to allow annular ring 140 to rotate without having any significant radial or axial play. The cen¬ tral opening defined by inner rim 176 of annular abut¬ ment walls 174 is such that the clamping means 114, clamping ring 160, beam delivery syste 500, and comb holder assembly 600 are allowed to be passed there¬ through. Annular ring 140 has a horizontal axis 141 comprising an external circumferential wall 142, an inboard radial wall 143, an outboard radial wall 144, and an internal annular wall 145. Gear teeth 146 are provided at the external circumferential wall 142 to match with a driving means (not shown). It is also contemplated to provide the inboard radial wall 143 with the proper gear teeth configuration to perform the same function. Instead of gear teeth 146, friction engagement may be contemplated. A rotation stage of the type manufactured by Newport, Klinger of Irvine, California, U.S.A. under model RTN 350, would include the annular ring 140 and provide it with the specific desired rotational speed and the amount of rotations per welding cycle. The internal wall 145 of annular ring 140 is defined, on the side adjacent to the inboard radial wall 143, by an annular abutment wall 147 and, on the side adjacent to the outboard radial wall 144, by a guiding wall 149. The inside diameter of the annular guiding wall 149 is such that it will allow the outer stage 16 to be slid in but will not allow significant radial play, and the axial dimension of the circumfer¬ ential guiding wall 149 will be defined by the quantity of outer stage annular plates 19 to be welded therein. The inside diameter 148 of the annular abut¬ ment wall 147 is such that it will allow the outer stage 16 to be bent slightly in the direction of the inboard radial wall 143 but will not allow the plates 19 in stage 16 to slide therethrough. Outboard radial wall 144 may be mounted with clamping means 114. It is also contemplated that a clamping force 115 may come from a source outside of the sub-assembly welding sta¬ tion; in that latter case, clamping means 114 would be replaced by a clamping ring holding means 117. Clamping ring 160 includes, on the side fac¬ ing the abutment wall 147 of annular ring 140, a pusher sleeve 162 and, on the side facing the clamping means 114, 115, stiffener ring 164. The pusher sleeve 162 is adapted to slide inside the guiding wall 149 of ring 140, and the sleeve is allowed to move axially freely but with restricted radial play. The inside dimension of the pusher sleeve 162 is similar to the inside diameter 148 of abutment wall 147 allowing, in this way, the stage 16 to be bent slightly in the direction of the outboard radial wall 144. The axial dimension of pusher sleeve 162 of clamping ring 160 is such that when clamping ring 160 is forced against stage 16 by clamping means 114 or 115, stiffener ring 164 does not interfere with the outboard radial wall 144 of annular ring 140, and stage 16 is positively pressed against abutment wall 147 of annular ring 140. Stiffener ring 164 is an extension of pusher sleeve 162 and integral therewith to form clamping ring 160 and is provided with two radial planar surfaces 165, 165a. The first radial planar surface 165 is adjacent to pusher sleeve 162, and the second radial planar surface 165a is on the other side of stiffener ring 164 in relation to first radial planar surface 165, and it faces clamping means 114 or clamping force 115, and the inside and outside diameters of stiffener ring 164 are such that stiffener ring 164 will not interfere with comb holder 600, beam delivery system 500, clamping means 114, or the abutment wall inside diameter 176 of structure 170. Column 120 is mounted to base 106 on the side of the inboard radial wall 143 of annular ring 140 and provided with a planar surface 122 to receive comb assembly 600 as will be described later. Planar surface 122 is parallel to the axial axis 141 of annu- lar ring 140 and perpendicular relative to base 106. Comb assembly 600 will now be described in reference to Figs. 2, 8, and 11. The comb assembly 600 includes a shank 610, a cylinder 608, cylinder mounting bolts 607, a blade holder assembly 630, and clamping bolt 631. Shank 610 is a rectangular longitudinal bar provided with a first planar surface 614 to be mounted adjacent to the column planar surface 122. A second planar surface 616 is provided on the other side of the shank 610 relative to the first planar surface 614 and is parallel therewith. A third planar surface 618 is at right angles with the first and second planar sur¬ faces 614, 616, and is parallel and faces base 106 when shank 610 is mounted to the column planar surface 122. A fourth planar surface 620 is provided on the top of the shank 610 and is parallel to the third planar sur- face 618. Longitudinal oblong slots 611, 611A pass through shank 610 between the first and second planar surfaces 614 and 616, and the slots are situated gener¬ ally at the ends of shank 610 opposite inboard radial wall 143 of annular ring 140. When shank 610 is mounted to planar surface 122, the distance between slots 611 and 611A is such that shank 610 will be allowed limited axial movement relative to the mounting bolts 606. Planar surface 122 of column 120 is pro¬ vided with tapped holes to receive mounting bolts 606. The other end of shank 610 relative to the first end is provided with a longitudinal recessed abutment wall 622 (Fig. 6), which is parallel and faces second planar surface 616 and is provided with a transversal recessed abutment wall 624. Abutment wall 624 is perpendicular and adjacent to abutment wall 622 and faces the second end of shank 610 to receive blade holder assembly 630 as will be described later. Cylinder 608, as shown in Fig. 2, is a spring return, single action, fluid cylinder mounted by means of bolts 607 on the third planar surface 618 of shank 610. A piston 609 extends from the cylinder and faces blade holder assembly 630 to engage and release it as will be described later. The longitudinal axis of cylinder 608 is parallel to planar surfaces 616 and 618 of shank 610. Shank 610 is provided with tapped holes to receive bolts 607. Thus, when shank 610 is mounted to column 120, the longitudinal axis of cylin- der 608 is parallel to axis 141 and perpendicular to the radial plane of annular ring 140. Cylinder 608 is provided with fluid inlet and control valves (not shown) to control the action and force of piston 609 against the blade holder assembly 630. In a preferred embodiment, blade holder assembly 630 includes a blade holder 632, spacer blades 650, and a pusher block 670. Blade holder 632 is in the form of a rectan- gular bar which had a first side 633 and an adjacent second side 638 cut longitudinally by a notch 634. The abutment wall 635 perpendicular to first side 633 and surface 636, both formed by notch 634, are such that when blade holder 632 is mounted to shank 610 by means of clamping bolts 631 in tapped hole 637. Abutment wall 635 of blade holder 632 sits against recessed abutment wall 622 of shank 610, and first side 633 sits on the surface 628 created between the recessed abutment walls 622 and 624. Second side 638 extends in front of sec- ond planar surface 616 of shank 610, and surface 636 of blade holder 632 does not interfere with third planar surface 618 of shank 610. Blade holder 632 is also provided with a third side 639 perpendicular to first side 633. A fourth side 640, parallel to first side 633, is provided with a longitudinal tee slot 641, parallel to sides 633, 638 or 639, to receive counter¬ part spacer blade 650 and pusher block 670 as will be described later. A first end of slot 641 faces piston 609 of cylinder 608 and a second end, on the other side of the blade holder relative to the first end, is provided with an end wall 642. End wall 642 is provided with two parallel planar surfaces 643, 644, and with the same transversal contour as the first three sides 638, 633, 639. The first planar surface 643, adjacent to second end of blade holder 632, extends beyond the fourth side 640 perpendicular to sides 638, 633, 639, such that it supports spacer blade 650 against axial forces as will be described later. A portion of second planar surface 644, which has the same dimension as the first planar surface 643, sits against recessed abutment wall 624 of shank 610 when blade holder 632 is mounted to shank 610. Thus, the longitudinal axis of blade holder 632 is parallel to axis 141 of annular ring 140 when holder 630 is mounted to shank 610. As shown in Fig. 9, spacer blade 650 is pro¬ vided with two planar parallel surfaces 651, 652. The outline thereof includes a tee section in the upper portion 653. The tee section is such that it engages longitudinally tee slot 641 of blade holder 632 freely but with limited transversal play when planar surfaces 651, 652 are projected perpendicular to sides 633, 638 or 639 of blade holder 632. A lower section 654 of spacer blade 650 is generally rectangular and projects at 655 from the base of the tee in the direction of side 638, such that when the spacer blade 650 is in blade holder 632, the end wall of projection 655 is substantially in the plane of side 638, and the upper edge of projection 655 clears surface 640 of blade holder 632 when spacer blade 650 is inserted in blade holder 632. The height 657 of the lower section 654, that is, the portion which extends below surface 640, is such as to engage between pairs of working pieces as will be described later. The lower portion 654 can have a nose section such as protrusion 656 which pro¬ jects forwardly in the direction of side 639. The nose or protrusion 656 is such that when working pieces are separated by spacing blade 650, the pre-welded seam level 658 (Figs. 11 and 8) is just above the upper edge of protrusion 656. The lower part of portion 654 of spacing blade 650 may be rectilinear (not shown) to separate rectilinear working pieces; concave, such as in the embodiment of Fig. 9, at 659 to separate circu¬ lar working pieces at the outside diameter; or convex at 660 to separate annular working pieces at the inside diameter thereof. Pusher block 670 is provided with generally the same transversal outline as the spacer blades 650, it being allowed to move longitudinally with limited transversal play. A first planar surface 671 is adja¬ cent and parallel to spacer blade 650, while a second planar surface 672 is parallel to the first planar sur¬ face 671 and on the opposite end of the pusher block 670. The end 672 is larger than the end 671 to accom¬ modate a conical recess 673 in order to receive piston 609 of cylinder 608 when cylinder 608 and blade holder 632 are mounted to shank 610, and pusher block 670 is inserted in the blade holder 632. The piston 609 is provided with a conical end to match cavity 673. The longitudinal distance between the first and second planar surfaces 671, 672 is such that when piston 609 is pressing on pusher block 670, planar surfaces 671, 672 are kept perpendicular to sides 638, 633 and 639 of blade holder 632. Shapes other than a tee slot may be considered for blade holder 632, spacing blade 650, and pusher block 670 as long as the function is the same. Having thus described the components of the welding station 100, reference will now be made to the loading and welding process of the station. In a first stage, a pair or a plurality of pairs of annular outer stages 16 are axially inserted, from the outboard radial wall 144, inside guiding wall 149 of annular ring 140 which allows stage 16 to be axially slid in freely but with limited radial play, thus keeping stages 16 concentric with annular ring 140. The pusher sleeve 162 of clamping ring 160 is inserted thereafter, and clamping means 114 is applied against the second radial surface 165a of stiffener ring 164 of clamping ring 160 such that clamping ring 160 pushes axially against stage 16 and against abutment wall 147 of annu- lar ring 140 and frictionally engages stages 16 in uni¬ son with annular ring 140, thus engaging stages 16 to rotate in unison with annular ring 140. Each stage is made up of at least a pair of annular plates 19. Spacer blades 650 are then mounted in blade holder 632 with pusher block 670 making up blade holder assembly 630, and the spacer blades 650 are inserted between pairs of plates 19 with the end wall 642 of blade holder 632 facing in the direction of clamping ring 160 and the longitudinal axis of blade holder assembly 630 being parallel to axis 141 of annular ring 140, the spacer blades 650 are then inserted with end wall 642 at one extremity followed by a spacer blade 650, a pair of plates 19, spacer blade 650, another pair of plates 19, and so on, to terminate with a spacer blade 650 and pusher block 670. The first and last spacer blade 650 adjacent to end wall 642 and pusher block 670 are used as friction blades. A spacer ring 130 may be used between a pair or plurality of pairs of external sub-assemblies 16a, to compensate for axial deflection created by spacer blades 650, forming spaces 138. Given the linear speed of welding and fusion bath solidification time such that when a plurality of seams 34 are being welded simultaneously, as will be described, the individual fusion bath of each pair of sub-assemblies does not interconnect itself with the adjacent one before it solidifies due to the spacers 650. Spacer ring 130 is an annular ring provided with two radial, generally planar, parallel surfaces 133, 134, a circumferential wall 131, and an internal wall 132. The diameter of external circumferential wall 131 is such that the spacer ring 130 is allowed to slide freely inside guiding wall 149 but with limited radial play. The internal diameter of internal wall 132 is similar to the inside diameter 148 of abutment wall 147 of annular ring 140. The spacing apart of the two radial, gener- ally planar surfaces 133, 134, determines the axial compensation of the stage 16. Blade holder assembly 630 is mounted to shank 610 of comb assembly 600 by means of clamping bolt 631 (Fig. ) and control valve of cylinder 608 is activated such that piston 609 of cylinder 608 engages longitudinally pusher block 670, thus pushing adjacent spacer blades 650 against adjacent pairs of plates 19 forming seams to be welded. Slots 611 and 611a of shank 610 provide the adjustment for the comb assembly 600 such that blade holder assembly 630 may be centered axially with the working pieces to be welded. As seen in Fig. 2, laser beam delivery system 500 is moved inside the internal circumference of annular outer stage 16 such that the longitudinal axis 503a, 507a, 513a of laser oblong focal beam 505, 509, 515 (see Figs. 2, 12a, 12b, 13a, 13b) is generally parallel to the longitudinal axis of second side 638 of blade holder 632 and generally perpendicular to the relative direction 676 of the working pieces to be welded and axially centered over the seams 20 or the plurality of seams to be welded, and the oblong focal beam 505, 509, 515 is slightly over the pre-welded seam level 658 (Fig. 11), and driving means is engaged such that annular ring 140 and stage 16 rotate in the rela¬ tive direction 676. The laser beam assembly 500 is shown as extending from the right of the rotation stage, when in fact it could approach from the left in Fig. 2. The assembly 500 could also be stationary on the left. Spacer blades 650 are frictionally engaged with plates 19 keeping seams to be welded together by means of the force applied by cylinder 608 to pusher block 670 thus to spacing blade 650 and separating the seams not to be welded between each other. The laser beam is energized such that a seam weld 34 or a plu¬ rality of seam welds 34 are produced simultaneously in front of blade holder assembly 630 at 20 to form outer stage sub-assembly 16a or a plurality of outer stage sub-assemblies 16a. The portions of the focal oblong beam 505, 509, 515, which happen to be facing spaces between welded seams 34 are defocused, thus losing focal density rapidly between the sides of the work¬ pieces which are only slightly convergent. When an outside clamping force 115 is used instead of clamping means 114, clamping force 115 is applied before the driving means is engaged. The distance 674 of the focal beam from second side 638 of blade holder 632 determines, up to the limit of capillarity of the molten material to be welded, the size of radius 30 (Fig. 10b). Laser pulse rate and linear welding speed determine welding pitch 32 of welded seam 34. In the next two following steps, the process is inverted. The laser beam is shut off, and the laser beam delivery system is pulled out of welding station 100. Blade holder assembly 630 is withdrawn from shank 610 and away from stage 16a. Clamping means 114 and clamping ring 160 are removed, and the outer stage sub-assembly 16a is removed from ring 140. A CO2 laser was illustrated in the above example. However, an Nd:Yag laser would probably be more efficient since the Yag laser beam can be more easily transmitted, such as by fiber optics. Referring now to Figs. 6, 8, 9, 10, and 11, another embodiment using an electron beam welding technique is described instead of a laser welding technique. An electron beam gun 700 is pointed at the workpieces to be welded in front of side wall 638 of blade holder 632, and after the driving means is engaged, the electron beam is energized and swept generally parallel to side wall 638 of blade holder 632 relatively from the pusher block 670 side to the end wall 642 side and then de-energized to return to the pusher block 670 side, where it is re-energized again to sweep in the direction of the end wall 642 side, and so on. This beam scanning technique allows a seam or a plurality of seams to be welded practically simultane¬ ously. The high speed scanning gives a similar result as with an oblong laser beam pulsing at a scanning frequency. The scanning direction may be reversed when the electron beam gun 700 is generally perpendicular to axis 141. The distance 674 of the focal beam from the side 638 of blade holder 632 determines up to the limit of capillarity of the molten material to be welded, the size of radius 30 (Fig. 10a); electron beam scanning rate and linear welding speed determine welding pitch 32 of welded seam 34. PHASE II Referring to Figs. 1, 3, 8, 9, 10, and 11, welding station 200 includes an annular ring 240 jour- naled to an axle 270 for rotation thereabout, a post 203 integrated to axle 270, a base 206, a column 220, a clamping ring 260, and a comb assembly 600. In Phase II, those elements which are similar to elements in Phase I have been identified by corresponding numerals, which have been raised by 100. Axle 270 is mounted to post 203, and post 203 is mounted to base 206 such that axis 271 of axle 270 is parallel to base 206, and axle 270 is provided with an external circumferential wall 272 which is defined on each side by annular abutment walls 274. The external dimension of circumferential wall 272 and the axial dimension between the abutment wall 274 are such as to allow the annular ring 240 to rotate without having radial or axial significant play. The outside diameter 276 of the annular abutment walls 274 is such as to allow the clamping means 214, clamping ring 260, beam delivery system 500, and comb holder assembly 600 to be passed thereabout. The rotation stage is similar to that described in relation to Phase I except that certain terms are reversed and the numerals have been raised by 100. Comb assembly 600, described in Phase I, is mounted to planar surface 222 in the same manner as described, that is, it is mounted to planar surface 222 of column 220. Having thus described the components of the welding station 200, reference will now be made to the loading and welding process of said station. A pair of plates or a plurality of pairs of annular plates forming stage 18 are axially inserted, from the outboard radial wall 244 on guiding wall 249 of annular ring 240. Pusher sleeve 262 of clamping ring 260 is inserted thereafter, and clamping means 214 is applied against the second radial surface 265a of stiffener ring 264 of clamping ring 260 such that clamping ring 260 pushes the plates of stage 18 against abutment wall 247 of annular ring 240 and frictionally engages the plates of stage 18 in unison with annular ring 240, thus engaging the annular plates to rotate in unison with annular ring 240. Spacer blades 650 are mounted in blade holder 632 with pusher block 670 to form blade holder assembly 630. The spacer blades 650 are inserted between pairs of plates of stage 18 in the same manner as with stage 16 in Phase I. Spacer ring 230 may be used between a pair or a plurality of pairs of internal plates, to compen¬ sate for radial deflection created by spacing blade 650. The welding equipment or technique used in Phase II are identical to Phase I. Laser beam delivery system 500 is moved out¬ side the external circumference of annular internal stage 18 such that the laser oblong focal beam or plu¬ rality of oblong focal beams are longitudinally gener- ally parallel to the longitudinal axis of the side 638 of blade holder 632 and generally perpendicular to the relative direction 676 of the working pieces to be welded and axially centered over the seams or the plu¬ rality of seams to be welded. The driving means engages such annular ring 240, and plates 18 rotate in the direction 676 from side 639 to side 638 of blade holder 632, and the laser beam is energized such that a seam weld 34 or a plurality of seam welds 34 are pro¬ duced simultaneously in front of blade holder assembly 630 at 22 to produce an internal stage sub-assembly 18a or a plurality of sub-assemblies 18a. In the next two following steps, the process is inverted. The laser beam is cut off, and the laser beam delivery system is pulled away from the welding station 200. Blade holder assembly 630 is withdrawn from shank 610 and away from stage 18. Clamping means 214 and clamping ring 260 are removed, and the internal stage sub-assembly 18a is pulled off of annular ring 240. In an alternative embodiment according to Figs. 7, 8, 9, 10, and 11, an electron beam gun 700 is pointed at the outside diameter of internal stage 18 to be welded, generally perpendicular to axis 271 of axle 270. The electron beam welding technique is the same as described in Phase I. PHASE III Referring to Figs. 1 and 4, assembly welding station 300 includes a rotation stage similar to that described in Phase I and II only the reference numerals have been raised by 100 compared to Phase II. Comb assembly 600, described in Phase I, is mounted to planar surface 322. Having thus described the components of the welding station 300, reference will now be made to the loading and welding process of this station. Annular end plate 12, internal stage sub- assembly 18a, external stage sub-assembly 16a, and annular end plate 14 are axially inserted in this order, from the outboard radial wall 344. Outside guiding wall 349 of annular ring 340 retains end plates 12, 14 and sub-assembly 18a with limited radial play, thus keeping sub-assembly 18a and end plates 12, 14 concentric with annular ring 340. A temporary guiding means (not shown) may be used to radially center outer sub-assembly 16a with end plates 12, 14, thus keeping external sub-assembly 16a concentric with annular ring 340. Pusher sleeve 362 of clamping ring 360 is inserted thereafter, and clamping means 314 is applied against the second radial surface 365a of stiffener ring 364 of clamping ring 360 such that clamping ring 360 axially pushes end plates 12 and 14 and external sub-assembly 16a against abutment wall 347 of annular ring 340 and frictionally engages covers 12, 14 and external sub-assembly 16a in unison with annular ring 340, thus engaging end plates 12, 14 and external sub- assembly 16a to rotate in unison with annular ring 340. Spacer blades 650 are mounted in blade holder 632 with pusher block 670 to form blade holder assembly 630. The spacer blades 650 are inserted between pairs of plates at the circumference of the annular end plates 12, 14 and external sub-assembly 16a, with the end wall 642 of blade holder 632 facing in the direction of clamping ring 360. A spacer blade 650 is inserted against end wall 642, adjacent end plate 14 and one plate of external sub-assembly 16a. The following spacer blades 650 are then inserted next to each pair of plates to terminate with a plate from outer sub-assembly 16a and end plate 12 as a pair and a spacer blade 650 and then pusher block 670. The first and last spacer blade 650 adjacent to end wall 642 and pusher block 670 are used as friction blades. Blade holder assembly 630 is mounted to shank 610 of comb assembly 600 by means of clamping bolt 631, and control valve of cylinder 608 is acti¬ vated such that piston 609 of cylinder 608 engages longitudinally pusher block 670, thus pushing adjacent spacing blade 650 against an adjacent counterpart which pushes against its adjacent counterpart to be welded which pushes adjacent spacing blade 650 and so on up to the relative last spacing blade which sits against end wall 642. Welding equipment or technique used in Phase III are identical to Phase I. Laser beam delivery system 500 is, relative to sub-assembly welding station 300, moved outside the external circumference of annular pre-welded bellows 10a to perform the welding step. The laser beam is shut off, and the laser beam delivery system is withdrawn from welding station 300. Blade holder assembly 630 is pulled out of shank 610 and out of pre-welded bellows 10a, clamping means 314 and clamping ring 360 are taken off, and pre- welded bellows 10a or a plurality of pre-welded bellows 10a are pulled out of annular ring 340. PHASE IV Referring to Figs. 5, 8, 9, 10, and 11, assembly welding station 400 includes an annular ring 440 journaled to a structure 470 for rotation therein, including column 420 mounted on a base 406. A clamping ring 460 and a comb assembly 600 are also provided. Elements which correspond to elements in Phases I, II and III have numerals which have been raised by 100 as compared to Phase III. Comb assembly 600, described in Phase I, is mounted to planar surface 422. A pre-welded bellows 10a is axially inserted from the outboard radial wall 444 inside guiding wall 449 of annular ring 440. A temporary guiding means (not shown) is inserted at the inside diameter of end plates 12, 14 and internal sub-assembly 18a, thus keeping the internal sub-assembly concentric with annu¬ lar ring 440. Pusher sleeve 462 of clamping ring 460 is then inserted thereafter, and clamping means 414 is applied against the second radial surface 465a of stiffener ring 464 of clamping ring 460 such that clamping ring 460 axially pushes end plates 12 and 14 and internal sub-assembly 18a against abutment wall 447 of annular ring 440 and frictionally engages end plates 12, 14 and internal sub-assembly 18a in unison with annular ring 440, thus engaging covers 12, 14, and internal sub-assembly 18a to rotate in unison with annular ring 440. The temporary guiding ring is then removed. Spacer blades 650 mounted in blade holder 632 are inserted between pairs of plates at the inside circumference of annular end plates 12, 14 and internal sub-assembly 18a. Spacer blades 650 are inserted with end wall 642 adjacent a spacer blade 650 and next to an end plate 14 and one plate of internal sub-assembly 18a. A spacer blade 650 is then inserted, and then a pair of plates to terminate with a plate from internal sub-assembly 18a and end plate 12 and then spacer blade 650 and pusher block 670. The first and last spacing blade 650 adjacent to end wall 642 and pusher block 670 are used as friction blades. Spacer ring 430 may be used between pre- welded bellows 10a or a plurality of pre-welded bellows 10a, to compensate for radial deflection created by spacer blade 650. The welding method and apparatus, described in relation to Phase IV, are identical to Phase I. Laser beam delivery system 500 is moved inside the annular pre-welded bellows 10a to perform the welding. The laser beam is shut off, and the laser beam delivery system is pulled out of welding station 400. Blade holder assembly 630 is withdrawn out of shank 610 and out of bellows 10. Clamping means 414 and clamping ring 460 are taken off, and the bellows 10 is pulled out of annular ring 440. It has also been contemplated that the column 120, 220, 320, 420 and comb assembly 600 may be located on the side adjacent to outboard radial wall 144, 244, 344, 444. Other pusher means may be contemplated instead of cylinder 608 as long as the function of compressing the spacer blades against adjacent work- pieces to be welded such that the workpieces to be welded are held together and kept apart between each other up to the welded seams 34 have solidified.

Claims: CLAIMS ; 1. A method of welding simultaneously a plu¬ rality of parallel continuous seams, including the steps of defining a welding station including a radia- tion welding source and determining a working plane spaced from the radiation welding source, wherein the working plane is within the focal depth of the welding source and intersects a plane containing the radiation welding source, spanning, with the radiation welding source, a welding zone including at the intersection of the working plane and the plane containing the welding source, maintaining a plurality of seams to be welded spaced apart and parallel, moving at least one of the welding stations and the plurality of seams to be welded, in unison, relative to one another such that the plurality of seams to be welded pass through the welding zone, energizing the radiation welding source, whereby the welded seams are formed simultaneously. 2. A method as defined in claim 1, wherein the radiation welding source is an electron beam welder wherein the electron beam is scanned transversally of the direction of movement and spans the welding zone. 3. A method as defined in claim 1, wherein the radiation welding source is a laser beam delivery sys- tem, the laser beam forming a focal pattern other than a circle at least spanning the welding zone. 4. A method of welding as defined in claim 1, wherein the plurality of seams to be welded are formed on workpieces which are in the form of sheets, and each pair of the sheets being held together to form a seam to be welded along contiguous edges of the sheets, a plurality of pairs of sheets being held in spaced-apart parallel relationship with the seams to be welded main- tained in an exposed condition to be passed through the welding zone. 5. A method of welding as defined in claim 4, wherein the welding station is stationary and the pairs of workpiece sheets held together are moved through the welding zone relative to the welding station. 6. A method as defined in claim 3, including passing the laser beam through a first optical element which projects the beam to form an oblong pattern at the working plane and in the welding zone, and spanning the welding zone to weld a plurality of seams simulta¬ neously by the laser beam. 7. A method as defined in claim 6, including passing the laser beam through a divider means which divides the beam into a plurality of beams, passing the plurality of beams through a further focal lens means to modify the beam to form at least a focused' oblong pattern with the major axis of the oblong pattern coin¬ cident with the welding zone. 8. A method as defined in claim 7, wherein a plurality of beams is generally parallel and the dis¬ tance between the beam divider means and the focal lens means can be changed without affecting the oblong pat¬ tern of the focused beam. 9. A method as defined in claim 7, wherein the plurality of beams is generally convergent and whereby the dimension of the oblong pattern of the focused beam along the major axis thereof can be varied in the work¬ ing plane and at the welding zone by adjusting the dis- tance between the beam divider means and the focal lens means. 10. A method as defined in claim 7, wherein the plurality of beams is substantially divergent such that the dimension of the oblong shaped pattern along the major axis of the oblong can be adjusted by varying the distance between the beam divider means and the focal lens means. 11. A method of manufacturing an annular bel¬ lows, including the steps of first preparing first and second annular end plates having outer and inner diame¬ ters, providing an outer stage of annular plates each having an outer diameter similar to the outer diameter of the first and second end plates, providing an inner stage of annular plates each having an inner diameter similar to the inner diameter of the first and second end plates; first, welding together one of the outer and inner stages by first joining adjacent pairs of the plates to form seams to be welded along the inner edges of the outer stage and the outer edges of the inner stage respectively, defining a welding station includ¬ ing a radiation welding source and a working plane at the welding station spaced from the radiation welding source within the focal depth of the welding source, and wherein the working plane intersects a plane con¬ taining the welding source, the radiation welding source spanning a welding zone at the intersection of the working plane and the plane containing the welding source, maintaining the seams to be welded of the pairs of plates spaced apart and parallel, moving said one of the outer and inner stages of the plates in a circular locus relative to the welding station such that the seams to be welded pass through the welding zone at the welding station, whereby the plurality of seams are continuously welded on the inner edges of the plates of the outer stage while the seams to be welded are main¬ tained parallel and spaced apart to form an outer sub- assembly and on the outer edges of the plates of the inner stage to form an inner sub-assembly; second, welding the other of the outer and inner stages; third, assembling the first and second end walls with the outer and inner sub-assemblies sandwiched therebetween and forming seams to be welded with pairs of the respective outer edges of the end plates and adjacent plates of the outer sub-assembly while maintaining the pairs of seams to be welded in spaced-apart and paral¬ lel relationship, and passing the seams to be welded through the welding zone in a circular locus, and form¬ ing seams to be welded with the inner edges of the end plates and the adjacent plates of the inner sub- assembly and intervening plates, maintaining the seams to be welded in spaced-apart parallel relationship and passing the seams to be welded through the welding zone in a circular locus, whereby at least an assembled bel- lows is formed. 12. A method as defined in claim 11, wherein the radiation welding source is an electron beam, wherein the electron beam is scanned generally transversally relative to the direction of the travel of the seams to be welded, and whereby the plurality of welded seams is produced virtually simultaneously. 13. A method as defined in claim 11, wherein the radiation welding source is a laser beam delivery sys¬ tem including a lens means whereby the laser beam is transformed at the working plane to at least a gener¬ ally oblong pattern coincident with the welding zone and transversal to the direction of the seams to be welded, whereby a plurality of welded seams are pro¬ duced simultaneously. 14. A method as defined in claim 2 or 12, wherein an electron beam gun is pointed at the welding zone and the electron beam is energized and is swept transversally of the direction of travel of the seams to be welded and is then de-energized and returned to its original position where it is re-energized again to sweep in the transverse direction. 15. A method as defined in claim 11, wherein the welding station is placed externally of the inner sub- assembly when the outer edges of the inner sub-assembly are being welded and externally of the assembled bel¬ lows when the seams of the outer edges of the outer sub-assembly and the end plates are being welded with the welding zone coincident with a circular locus of the outer edges of the respective sub-assemblies, and the welding station is partially located in a central opening formed by the annular sub-assemblies when the inner edges of the outer sub-assembly are being welded and the inner edges of the assembled bellows are being welded. 16. A method as defined in claim 11, wherein the bellows to be formed is assembled from first and second end plates, outer and inner sub-assemblies, with each sub-assembly including at least a pair of annular plates, such that at least two welded seams are formed on the outer edges of the outer sub-assembly and the inner edges of the inner sub-assembly with the end plates, and at least one welded seam is formed on the inner edges of the outer sub-assembly and the outer edges of the inner sub-assembly. 17. A method as defined in claim 11, wherein during the step of welding the outer sub-assembly and inner sub-assembly, a plurality of sub-assemblies can be assembled by providing spacers between adjacent sub- assemblies passing through the welding zone. 18. A method for partially altering the state of the composition of a workpiece by thermal energy with at least a first laser beam, including placing the workpieces in a working plane within the focal depth of the laser beam, locating at least an optical element in the laser beam upstream of the working plane in order to project the laser beam at the working plane with a predetermined oblong pattern, providing an application zone on the workpieces including the working plane which is at least the width of the area of partially altering the state of the composition of the workpiece, and the oblong pattern of the laser beam spans at least the application zone. 19. A method as defined in claim 18, wherein the oblong pattern of the laser beam has a major axis extending transversely of the application zone. 20. A method as defined in claim 18, wherein the further step of locating a second optical element between the first optical element and the working plane, whereby the second optical element will focalize the beam in its predetermined oblong pattern at the working plane. 21. A method as defined in claim 20, wherein the major axis of the oblong pattern is adjusted by con¬ trolling the distance between the first and second op¬ tical elements. 22. A method as defined in claim 20, wherein the first optical element is a beam divider to divide the laser beam into a plurality of beams to extend between the first and second optical elements and are generally aligned, and the second optical element is effective for focalizing the beams at the working plane. 23. A method as defined in claim 22, wherein the divided laser beams extend parallel between the first and second optical elements. 24. A method as defined in claim 22, wherein the divided laser beams diverge between the first and sec¬ ond optical elements. 25. A method as defined in claim 22, wherein the divided laser beams converge between the first and sec¬ ond optical elements. 26. A method as defined in claim 22, wherein the beams form an oblong pattern at the working plane and are aligned along the major axis of the respective oblong patterns. 27. A method as defined in claim 20, wherein a third optical element is located between the first and second optical elements, and the third optical element is a beam divider which divides up the beams into a plurality of aligned beams each having an oblong cross- section, and the second optical means focalizing the divided oblong beams such that the major axes of each oblong beam pattern on the working plane are aligned. 28. A method as defined in claim 6, including passing the laser beam through a second optical element to focus the generally oblong pattern, and the extent of the oblong pattern in its major axis is adjusted by adjusting the distance between the first and second lens means. 29. An apparatus for welding simultaneously a plurality of parallel continuous seams to join several workpieces in pairs, including jig means for maintain¬ ing the workpieces and for holding the workpieces and the seams to be welded in spaced-apart and parallel relationship, welding means including a radiation weld¬ ing source and a working plane spaced apart from the radiation welding source and within the focal depth of the welding source, means mounting the welding source in a plane intersecting the working plane, means asso- ciated with the welding station such that the welding source can span a welding zone at the intersection of the working plane and the plane containing the welding source, means for moving one of the welding station and the jig such that the seams to be welded pass through the welding zone whereby a plurality of welded seams are formed simultaneously. 30. An apparatus as defined in claim 29, whereby the workpieces are in the form of thin plates having edges and the welded seams are to be formed at the con¬ tiguous edges of pairs of plates. 31. An apparatus as defined in claim 29, wherein the means for maintaining the seams spaced apart and parallel include a comb assembly mounted on the jig means wherein the comb includes a first holder means and abutment means and a plurality of spacer plates h. .d by the holder means, the holder means having a longitudinal axis and the spacer plates are movable in the longitudinal axis of the holder but retained against movement in other directions, the holder means being mounted such that the longitudinal axis thereof extends transversally of the direction of movement of the seams to be welded and is located adjacent the welding zone, the spacer plates being adapted to be inserted between pairs of workpieces at the seams to be welded, and means for applying pressure on the spacer plates in the longitudinal axis of the holder for main¬ taining the edges of the pairs forming the seams to be welded close together as they enter the welding zone. 32. An apparatus as defined in claim 31, wherein the means for maintaining the seams spaced apart and parallel include the holder means defined by a block with a track defined in the longitudinal axis of the holder and the spacer plates can slide in the track in the holder in the longitudinal axis but are retained against movement in the direction of travel of the seams to be welded, and a piston and cylinder arrange¬ ment is provided in the longitudinal axis of the holder with the cylinder mounted to the comb assembly and the piston adapted to abut one of the spacer plates in a series whereby pressure is transmitted from a first spacer blade to a pair of workpieces to be welded to a further spacer blade and then to a further pair of workpieces to be welded, and so on, against the abut- ment means on the holder, and the workpieces forming seams to be welded move relative to the comb into the welding zone adjacent to the holder. 33. An apparatus as defined in claim 29, wherein the workpieces are in the form of annular plates having outer and inner circular edges with the inner edge defining a circular opening, the jig including a first stationary frame member in an annular wheel rotatable in the frame member, the wheel having seat means for receiving the annular plates to be welded, clamp means are associated with the wheel means for clamping the plates to be welded with the wheel such that when the wheel rotates within the fixed frame, the plates rotate with the wheel with predetermined edges of the plates passing through the welding zone. 34. An apparatus as defined in claim 33, wherein the wheel, in the case of welding the outer edges of the annular plates, has a circumferentially defined seat for receiving the inner edges of the plates so that the outer edges are exposed. 35. An apparatus as defined in claim 33, wherein the wheel has an internal seat for receiving the annu¬ lar plates such that the outer edges of the annular plates are received within the seat in the wheel and the inner edges of the annular plates are exposed. 36. An apparatus as defined in claim 34, wherein the jig is provided for assembling a bellows, wherein the bellows is made up of a pair of end plates sand¬ wiching an outer sub-assembly of annular plates having an outer diameter similar to the outer diameter of the end plates, and an inner sub-assembly made up of annu¬ lar plates having an inner diameter the same as the inner diameter of the end plates, the wheel having a seat about the outer periphery thereof adapted to receive an assembly of the end plates sandwiching the sub-assemblies such that the outer diameter edges of the end plates and sub-assemblies are exposed and pass through the welding zone, and clamp means are provided on the wheel adapted to clamp the end plates and the sub-assemblies for forming the bellows. 37- An apparatus as defined in claim 35, wherein the wheel has an inner seat to receive at least a pair of annular end plates sandwiching at least outer and inner sub-assemblies of annular plates for forming a bellows, wherein the end plates and the inner and outer sub-assemblies are held within the seat of the wheel with the inner edges of the end plates and inner sub- assembly inner edges being exposed and adapted to pass through the welding zone, and clamp means for clamping the end plates and the inner and outer sub-assemblies in the seat defined in the wheel. 38. An apparatus as defined in claim 34, wherein the welding station includes a movable base member to which the welding source is movably mounted relative to the base, the movable base member being adapted to move to a position adjacent the outer periphery of the wheel in the jig such that the welding zone can be located at the outer edges of the plates adjacent the means for maintaining the seams spaced apart and downstream thereof. 39. An apparatus as defined in claim 35, wherein the welding station includes a welding head which is movable relative to the jig and which can be inserted within the opening defined by the inner edges of the plates mounted in the jig, and the head including the welding source arranged such that the welding zone is at the inner edges of the seams to be welded. 40. An apparatus as defined in claim 29, wherein the welding source is an electron beam generating means wherein the electron beam is scanned transversely of the direction of movement of the seams to be welded, in the welding zone such that a plurality of welded seams are produced virtually simultaneously. 41. An apparatus as defined in claim 40, wherein the electron beam generating means has an electron beam gun pointed towards the seams to be welded whereby the electron beam gun is energized and swept transversely of the seams in the axis of the welding zone and is de- energized at the end of the scan and returned to its original position where it is re-energized and the sweep is repeated. 42. An apparatus as defined in claim 29, wherein the radiation welding source is a laser beam generator and delivery system which includes optical elements to transform the laser beam as such that it has an oblong pattern at the working plane and the oblong pattern has a major axis coincident with the welding zone which spans the plurality of seams to be welded. 43. An apparatus as defined in claim 42, wherein the laser beam delivery system has a second optical element to focus the generally oblong pattern beam and that the extent of the oblong pattern in the major axis can be adjusted and means are provided for adjusting the distance between the first and second optical ele- ments to provide the adjustment of the length of the oblong pattern of the laser beam in the major axis. 44. An apparatus as defined in claim 42, wherein the optical elements includes a first beam divider means dividing the laser beam into a plurality of beams and second optical elements to produce a generally oblong shaped beam focused at the working plane with the major axis of the oblong shape being in the longi¬ tudinal axis of the welding zone. 45. An apparatus as defined in claim 44, wherein the plurality of beams are generally parallel and means are provided for adjusting the distance between the first beam divider means and the second lens means without affecting the shape of the focus beams. 46. An apparatus as define din claim 44, wherein the plurality of beams are generally convergent, and means are provided for adjusting the distance between the first beam divider means and the second optical elements such that the extent of the oblong pattern of the beam in the working plane is adjusted to a desired length in the major axis of the beam. 47. An apparatus as defined in claim 44, wherein the plurality of beams are generally divergent, and means are provided for adjusting the distance between the first beam divider means and the second optical elements to adjust the extent of the longitudinal dimension of the oblong pattern of the beam in the working plane. 48. An apparatus as defined in claim 44, wherein the plurality of divided beams have circular cross- sections. 49. An apparatus as defined in claim 44, wherein the plurality of divided beams each have oblong cross- sections. 50. An apparatus for partially altering the state of the composition of a workpiece by thermal energy comprising at least a laser beam generating means, means defining a working plane in which work¬ pieces are placed, at least a first optical element located in the path of the laser beam such that a geo- metric pattern other than a circle is provided at the working plane, an application zone is provided on the workpieces at the working plane which is at least the width of the area of partially altering the state of the composition of the workpiece, and the geometric pattern other than a circle of the laser beam spans at least the application zone. 51. An apparatus as defined in claim 50, wherein the optical element in the path of the laser beam is a lens or mirror for modifying the laser beam to form the geometric pattern on the working plane. 52. An apparatus as defined in claim 50, wherein a second optical element is provided between the first optical element and the working plane, and the second optical element focalizes the beam on the working plane. 53. An apparatus as defined in claim 52, wherein the first optical element is a beam divider to provide a plurality of laser beams extending between the first and second optical elements, and the second optical element focalizes the divided beams on the working plane. 54. An apparatus as defined in claim 53, wherein the first optical element is a diffractive optical element. 55. An apparatus as defined in claim 53, wherein the plurality of beams extending between the first and second optical elements are parallel and are aligned. 56. An apparatus as defined in claim 53, wherein the divided laser beams between the first and second optical elements are divergent. 57- An apparatus as defined in claim 53, wherein the divided laser beams between the first and second optical elements are convergent. 58. An apparatus as defined in claim 52, wherein adjusting means are provided to control the distance between the first and second optical elements so as to vary the beam pattern in the working plane. 59. An apparatus as defined in claim 58, wherein the adjusting means controlling the distance between the first and second optical elements is effective to vary the major axis of the oblong beam pattern in the working plane. 60. An apparatus as defined in claim 55, wherein adjustment means are provided for adjusting the dis¬ tance between the first and second optical elements so as to adjust the focalization of the pattern on the working plane and to adjust the intensity of the laser energy at the working plane. 61. An apparatus as defined in claim 60, wherein the first optical element is a diffractive optical element. 62. An apparatus as defined in claim 50, wherein the optical element is a transmission lens. 63. An apparatus as defined in claim 50, wherein the optical element is a reflective mirror. 64. An apparatus for delivering a plurality of laser beams generated in parallel, including a first optical element for focusing the laser beams to a pre¬ determined focal point, fiber optics means having a receiving end and a delivery end, means for maintaining the receiving end at the predetermined focal point so that the laser beams may be transmitted by the fiber optic means, and a second optical element at the de¬ livery end of the fiber optics means for projecting the laser beams. 65. An apparatus as defined in claim 64, wherein the first optical element is a diffractive optical element. 66. An apparatus as defined in claim 50, wherein the geometric pattern formed on the working plane is oblong. 67. An apparatus as defined in claim 50, wherein the geometric pattern formed on the working plane is at least an annulus. 68. A method for partially altering the state of the composition of a workpiece by thermal energy with at least a first laser beam, including a working plane, including placing the workpieces in a working plane within the focal depth of the laser beam, locating at least an optical element in the laser beam upstream of the working plane in order to project the laser beam at the working plane with a predetermined geometric pattern other than a circular spot, providing an appli¬ cation zone on the workpieces which is at least the width of the area of partially altering the state of the composition of the workpiece, and the geometric pattern of the laser beam spans at least the applica¬ tion zone. 69. A method as defined in claim 68, wherein the geometric pattern is an annulus.

Inventors: RANCOURT YVON, RANCOURT, YVON
Applicants: RANCOURT YVON, RANCOURT, YVON
Application year: 1993
Main classification: B23K26
IPC codes: B21D19, B23K15, B23K26