AN APPARATUS FOR JOINTING PLATE-SHAPED MATERIALS BY ONE-SIDED WELDING

Abstract: Apparatus for jointing plate-shaped materials by one-sided welding, comprising means for holding the plate-shaped materials during the welding operation; a horizontally arranged backing beam (7) having at the top means (12, 20) for receiving and maintaining in position a backing strip (13) to be kept against the underside of the weld seam to be formed, a lifting system (10) for up-and-down movement of the horizontal beam; means (34) for executing the one-sided welding operation, as well as a tilting mechanism by means of which the beam (7) is tiltable through an angle to either side relative to the longitudinal median plane thereof.

Description: welding The present invention relates to an apparatus for jointing plate-shaped materials by one-sided welding. Such an apparatus is disclosed in Dutch patent application 6910223. It is not possible with this prior art apparatus to weld 5 plate-shaped materials of unequal thickness. Also known is a welding method wherein the plates to be jointed are positioned with the plate edges in the contemplated manner relatively to each other, secured and subsequently one- sidedly welded by a combination of CO2 welding for depositing a root 10 pass, and subsequently finish welding by means of submerged welding arc (SA welding) , using an SA welding machine with an oscillation system. This combination technique can be used with plate thicknesses of 8 to 9 mm and more. The plates should be pre-treated and the plate edges should be bevelled. The plates can be marked out and 5 cut to the proper size and afterwards be buffed against ech other without advance opening, with the plate edges forming a Vee butt joint. For maintaining the relative positions of the plates, these are kept together by installing steel bridges over the Vee butt joint and by tacking them to the plates. During the first welding ' 0 pass, the jointing bridges are removed again just before the welding machine has approched the bridges. After the total welding operation has been carried out, the tacks used for securing the steel bridges are to be removed, e.g. by grinding. As advantages of the combined CO2 + one sided SA welding 5 method can be mentioned, in summary, the possibility of marking out the plates to the proper size and the circumstance that the plates need not be turned. Depending on the plate thickness, moreover, a single welding pass may be sufficient. However, also drawbacks can be mentioned, including the additional rough-machining for bevelling the 0 plate edges, which entails extra work and gas consumption; the manufacture and installation of the steel bridgesfor temporarily keeping the plates together and the subsequent removal of these bridge and tacks. Furthermore, two types of welding apparatus are necessary, with the CO2 welding apparatus preceding the SA welding machine. As 5 indicated in the above, depending on the plate thickness, a single welding pass may be sufficient. In case not permitted by the plate thickness, the SA welding operation will have to be repeated one or more times. Finally, a welding method has also been developed in practice in which the plates are jointed via the plate edges by one-sided butt welding, while using exclusively SA welding by means of an SA welding machine with an oscillation system. In this method as well, the plates should be clamped and an advance opening of at least 3 to 4 mm is to be taken into account. When plates of thicknesses of over 12 mm are used for this purpose, an advance opening of 3 to 4 mm or more is to be provided between the plate edges, while, more- over, said edges are to be provided with a butted nose for obtaining a Y-weld seam. A major drawback of this one-sided butt welding by means of SA welding experienced in practice is that owing to the need of maintaining an advance opening of 3 to 4 mm and more, it is not possible to mark out the work to normal sizes. Besides, such an advance opening requires much welding material, while this method also has the drawbacks of the need to use temporary steel bridge joints, the operation in one ore more welding passes and the additional pre-treatment to produce a Y-weld seam at a plate thickness of 12 mm or more. A further development in the one-sided butt welding art com¬ prises horizontally positioning two or more plates to be jointed by butt welding by means of clamping members with the plate edges in juxtaposition to each other, while maintaining an advance opening between the plate edges of e.g. maximally 3.25 mm; providing a backing strip against the underside of the plate edges, and subse¬ quently one-sidedly welding the plates from the top using pulsating current under powder shield. Plates with a thickness of up to about 10 mm can thus be butt welded without a pre-treatment, and without an advance opening between the plate edges. Plate thicknesses of above 10 mm to about 16 mm, true, can also be butt welded but then an advance opening should be maintained with the above mentioned maximum value of about 3.25 mm. There is no need to pre-treating the plate edges in this case to produce a Y-seam or V-seam. For plate thiclcnesses of 16 mm and more, a pre-treatment to produce a Y-seam is desirable, though not always strictly necessary and depending on the requirements set. On the other hand, even then an advance- opening of about 3.25 ram is to be maintained. However,while maintaining this advance opening of maximally about 3.25 mm, the plate thickness in this welding method has shifted from 12 mm to 15 mm or more. Moreover, it has been found that it is not necessary to temporarily joint the two plates through steel bridges, so that the manufacture of the steel bridges, and the additional operation for removing the steel bridges and the temporary tacks therefrom are no longer necessary. Insofar as it is yet desirabl to joint the plates, prior to the actual welding operation in the prior improved one-sided submerged-arc welding type process with pulsating current by jointing the plate edges directly through tack- welds in the seam between said edges. The plates can be marked out to the normal size, or, in case a smaller advance opening of maximally 3.25 mm has to be used, with a minimum correction, making allowance for a slight shrinkage. Furthermore, a single welding pass will be sufficient in this welding method. As a result and in combination with butt welding and with the maintenance, if necessary, of only a small advance opening to maximally about 3.25 mm, the welding method results in an appreciable saving in welding stock and in labour owing to there being no edges to be bevelled. The welding machines with which the above prior art welding methods are carried out are not suitable for jointing plate-shaped materials of unequal thickness. It is an object of the present invention to provide a welding apparatus for one-sided welding by means of which both plate-shaped materials of equal thickness and such materials but of unequal thickness can be welded. According to the present invention, there is provided for achieving the above object, an apparatus for jointing plate-shaped materials by one-sided welding, comprisingmembers for clamping said materials during the welding operation, a horizontally arranged backing beam having means at its top for receiving and maintaining in position a backing strip to be held against the underside of the weld seam to be formed; a lifting system for up-and-down movement of the horizontal backing beam; means for performing the one-sided welding operation, as well as a tilting mechanism by means of which side relative to the longitudinal median plane thereof. Due to the tiltable construction of the backing beam associated with the welding apparatus according to the present in- vention, also plates of unequal thickness can be jointed. If desired, the top of the backing beam, as viewed in cross section, can be designed non-planar in outward direction, so that a better contiguity of the top of the backing beam with the seam joint between the plates can be obtained in the corner area of the two plates of unequal thick- ness. According to a further elaboration of the welding apparatus according to the present invention, wherein the backing beam is received in longitudinal direction in a housing having a bottom and two sidewalls situated on both sides of the backing beam, the tilting mechanism comprises a pivot coacting with a tilt limiter, situated in the longitudinal median plane of the backing beam, said pivot allowing the bottom of the housing to be pivotally supported on the lifting system. Such an embodiment of the tilting mechanism is very suitable for use with not too large differences in thickness between the plates to be welded. As the axis of the tilting movement, however, is spaced a certain distance from the underside of the weld seam, the longitudinal median plane of the backing beam will come to lie further from the weld seam when the difference in thickness between the plate increases and said beam is tilted, so that also the positioning of the backing strip lying on said beam will not be optimum. By laterally shifting the plates to be welded, the proper position of the weld seam relative to the longitudinal medinal plane of the backing beam, and strip, respectively, will then have to be found. For that reason, according to a preferred embodiment of the present invention, the welding apparatus according to the present invention is fitted in such a manner that the tilting mechanism comprises means for moving the horizontal axis of the tilting movement situated in the median longitudinal plane of the backing beam to adjacent the underside of the weld seam to be formed. In a still furthe preferred embodiment of the welding apparatus accordingto the present invention, wherein the lifting system is combined with a pressure sys¬ tem including a pressure hose, the apparatus is characterized in that BAD ORIGIN* 1 -* there is mounted on the lifting system an elongate, hollow tube of substantially rectangular cross-section, disposed parallel to the backing beam the top wall of said sleeve including two parallel guiding slots in longitudinal direction; two enlongate parallel supporting sections extending through said slots are accommodated in the tube, each section being supported with the undersides thereof in longitudinal direction on flexible pressure hoses disposed on the bottom in the tube, said hoses forming the pressure system, while the housing is carried on the top of the supporting section by means of elongate strips extending laterally from the sidewalls of the housing and being affixed thereto. The coaction between the lifting system and the pressure system is such that the lifting system, driven e.g. hydraulically or pneumatically, lifts the backing beam and the superposed backing strip in the direction of the weld seam until that side of said beam being present underneath the plate having the largest thickness abuts against the underside of said plate. By allowing a pressure medium, e.g. compressed air, to enter the pressure hose at the free side of the backing beam, said side is moved further upwards, with simultaneous tilting of the assembly of backing beam and strip until the free side of said beam contacts the plate of smallest thickness. Owing to the chosen construction form of the combination of the lifting system and a pressure system, the axis of the tilting movement lies closely under the weld seam. As a result, within the scope of the one-sided welding, operation plates can be jointed whose thicknesses differ appreciably. In another preferred embodiment of the apparatus according to the present invention, the housing is pivotally connected to a hood which can be swung longitudinally over the top of the backing beam, whil it is further advantageous in this embodiment that the hood at the end opposite the welded joint to be made is fitted with a longitudinal rib parallel to the backing beam. Said rib may have a rounded top and e.g. a semi-circular cross-section. However, it is also possible to provide a longitudinal rib having an angular top, i.e. a longitudinal rib of triangular cross-section. Thus designed, the apparatus according to the present invention is not restricted to the jointing of plates by one-sided butt welding, but the. welding apparatus can also be used as fillet welding apparatus by means of which a beam, e.g. a stiffening beam, can be welded onto a plate, here too, for that matter after the beam has been provisionally tack-welded to the plate. In such a situatio the welding apparatus according to the present: Hn^ήtio can be pro¬ vided with a CO2 welding apparatus or a submerged arc welding apparatus and e.g. an additional guide beam can be provided and the welding apparatus fitted with a double welding gun can be attached thereto. The plate with the stiffening beam to be mounted thereon by fillet welding, said beam being maintained in position provisionally by tack welds, is arranged with the stiffening beam above the backing beam whose top is protected by the hood swung over said top. The plate is kept in position by the clamping members, after which the backing beam is lifted into such a position that by means of the hood pressed against the bottom of the plate, this is subjected to an upward deflection. Depending on the plate thickness, there is effected a stronger or less strong deflection. Thereafter, fillet welding can be performed on both sides of the stiffening beam. When the welding operation is completed, the backing beam is again lowered, after which the plate with a following stiffening beam provisionally installed thereon by means of tack welds can be brought in position, etc. As described above, the preferred embodiment of the welding apparatus according to the present invention permits welding a beam to a plate in a single pass simultaneously in the two corner areas enclosed between the beam and the plate which is a substantial advantage. Moreover, it is achieved due to the pre-tension introduced by the deflection adjacent the beam that, after the welding the plate has remained flat. As a result, a qualitatively better end product is obtained and a more efficient assembly is ensured as the plate need net be subjected to an elongation or stretching operation. For the purpose of a welding operation for joining plates along the plate edges by one-sided butt welding by means of submerged arc welding at pulsating current, the fitting of backing strip on the backing beam can be appreciably simplified by mounting in the welding apparatus according to the present invention, as viewed in longitudinal direction, beyond the one end face of the backing beam, a stock length of the strip and beyond the other end face a reel about which the finished supporting strip can be wound. As a result,the backing strip need be withdrawn from the stock length and be displaced over the top of said beam towards the reel and be attached thereto only at the beginning of an intended series of plate welding operations. After a welding operation, it will then be sufficient, by rotation of the reel, to wind the finished strip over such a length thereof about the reel that on said beam the place of the finished strip is occupied by the new strip withdrawn from the stock length. In order that, during the drawing of the strip over the beam, the strip may be prevented from leaving the beam laterally, there are provided on the top of the backing beam in tworows a plurality of guid pins locked in said beam and projecting above it and being under spring tension, the distance between the rows being at least about equal to the width of the strip. The present invention also relates to an apparatus for jointing plate-shaped materials by one-sided welding, comprising means for holding the plate-shaped materials during the welding operation; a horizontally backing arranged backing beam fitted on the top with means for receiving and maintaining in position, a backing strip to be held against the underside of the weld seam to be formed; a lifting system for the up-and-down movement of the horizontal beam; ' means- for executing the one-sided welding operation, the means . for holding the plate-shaped materials during the welding operation comprising a pressure element arranged at the same side as the means forexecuting the welding operation above the plate-shaped materials to be welded and being movalbe in synchronism with the means for executing the welding operation over the weld seam to be formed, said pressure element including a pressure knob containing a plurality of rollers which can be pressed onto the plate edges to be welded one-sidedly by rolling the same over the weld seam at right angles thereto, upstream and downstream of the welding area defined by the means for executing the welding operation. Such a welding apparatus makes for a compact construction, which possibility is enhanced when the means for executing the welding operation and the pressure element are combined to a single member. A major advantage of the apparatus in which the plates are pressed in the direct surroundings of the weld position only by means of the pressure element, is that it is applicable not only to the one-sided welding of flat plate materials, but also to plate materials having shaped, curved surfaces, e.g. to the one-sided welding of vessels or tanks. The welding apparatus according to the present invention can be used generally within the scope of the prior art techniques for one-sided welding, including one-sided submerged arc welding at pulsating current, the plate-shaped materials being of equal or unequal thickness. The welding apparatus according to the present invention even allows handling plate thicknesses of over 15 mm, e.g. of 20 mm. by means of one-sided butt welding at pulsating current under powder shield, but in that case an advance opening of adjested size has to be maintained. Some embodiments of the welding apparatus according to the present invention will now be described, by way of example, with reference to the accompanying drawings, in which: Fig.l is a side view of a plate welding line by means of which ships' plates can be welded along their plate edges; Fig.2 is a cross-section of an assembly of supporting beams and upper beams coacting therewith, associated with the welding apparatus, for clamping the plates to be welded, and a backing beamhaving a hinged hood pivoted thereto and fitted with a tilting mechanism, the axis of the tilting movement lying a given distance below the backing beam; Fig.3 is a diagrammatic cross-sectional view, perpendicular to the transport direction of the plates, of a stock length for the backing strip, a reel for finished strip and coacting roller trios for keeping the backing strip taut; Fig.4 is a diagrammatic cross-sectional view, of the backing beam fitted with two rows of guide pins between which the backing strip can be advanced; Fig.5 shows assembly as that shown in Fig.2, however, fitted with a tilting mechanism, the axis of the tilting movement being at the top of the backing beam. Fig.6 is a side view of a plate welding line fitted with a welding apparatus in which the means for holding the plates to be welded have the form of a pressure kncb operative only locally in the weld area, which knob, coacting with the welding means, can be moved synchronously along the weld seam. In the plate welding line shown in Fig.l, reference numeral 1 represents the supply roller track for the plates to be welded and 2 represents the delivery roller conveyor for the plate material welded, while 3 indicates the welding installation. In said welding installation 3 there are provided within a tower frame 4 as aclamping member, supporting beams 5, said upper beams 6 being movable towards and away from said supporting beams and clampable there between during the welding of the plates to be jointed. The backing beam 7 is disposed between the supporting beams, while at 8 is indicated a tack welding apparatus by means of which the plates to be welded, which are being transported in the direction of the arrow P towards and away from the welding installation, are temporarily tack welded. Backing beam 7 (Fig.2) is supported via a pivot 9 with gear transmission on a lifting system 10 adapted for pneumatic up-and- down movement. Backing beam 7 is pivotal to both sides, while the amount of travel of the tilting movement is defined by the tilt limiter 11, e.g. to a tilting angle of 10°, as shown in Fig.2. At the top, backing beam 7 has a trough-shaped recess 12 wherein the backing strip 13 (Fig.4) is carried. Housing 14 of beam 7 is connected pivotally at 15 to the hood 16, fitted with the rib 17 at the side opposite the plate. By swinging hood 16 to the right in the drawing, beam 7 within housing 14 thereof is protected when it is pressed in this position with the hood and the rib 17 against a plate and is jointed to a beam by means of fillet welding. Fig.3 shows diagrammatically at 18 a member where the stock length of backing strip 13 is present. Strip 13, centred by guide pins 20 (Fig.4) locked in the backing beam under the pressure of springs 21, is passed through the trough-shaped recess 12 in the top of said beam towards the reel and wound about said reel. By rotation of the reel 19 in' clockwise direction, strip 13 is drawn to the right in the drawing to provide beam 7 with a required or desired new length of strip. To ensure a stable position and tautness of the strip on the beam, the strip is kept under a given tension by means of the two roller tios 22,23 arranged as clamping members on either side of the beam 7. Fig. 5 shows at 30 a pair of strips affixed longitudinally to the housing 14 of the backing beam. By means of strips 30, the entire assembly of housing 14, beam 7 and backing strip not indicated in Fig.5 in the trough-shaped recess 12, is freely supported on the supporting sections 31, which within the tube 32, each find supporting longitudinal direction on flexible pressure hoses 33. By means of the lifting system 10, beam 7, fitted in the trough-shaped recess 12 with the backing strip, is moved upwards untilbeam 7 contacts, e.g. at the right hand side in Fig.5, the plate of the largest thickness, not shown. By supplying compressed air into the left pressure hose 33 as viewed in Fig.5 the beam and the strip situated in the trough-shaped recess 12 are tilted to the right and pressed with left side thereof against the plate of the smallest thickness, not shown. In the plate welding line for flat plates, shown in Fig.6, the arrow P indicates the welding direction. At 33 is indicated the assembly of welding installation 34 adapted for pulsating submerged arc welding, and pressure element 35. Welding installation 35 comprises welding wire drum 36, welding head 37 and powder supply line 38 and is fed via the electric cables 39, and is suspended movably from carrier beam 40. Pressure element 35 is movably suspended from carrier beam 41 and includes tractor 42 and pressure knob 43, which includes two spaced-apart parallel plate-shaped supporting wings 44, wherein a plurality of pressure rollers 45 are ' mounted. Pressure rollers 45 have such a width as to sufficiently bridge the welding gap between the plates to be welded, so as to maintain the plate edges, under the influence of the adjustable pressure force exerted through the rollers during the progress of the welding process, properly flat and relatively positioned locally in the weld area. During the welding process, the pressure element 35 and the welding installation 34 move synchronously in the direction of arrow P. It will be clear that modifications can be made in the welding apparatus as described hereinbefore and shown in the drawing, without departing from the scope of the present invention.

Claims: C L A I M S 1. An apparatus for jointing plate-shaped materials by one-sided welding, comprising members for holding the plate-shaped materials during the welding operation; a horizontally arranged backing beam 7 having at the top means 12,20 for receiving and maintaining in position a backing strip 13 to be kept against the underside of the weld seam to be formed; a lifting system 10 for up-and-down movement of the horizontal beam; means 34 for executing the one-sided welding operation, as well as a tilting mechanism by means of which the beam 7 is tiltable through an angle to either side relative to the longitudinal median plane thereof. 2. A welding apparatus according to claim 1, in which the backing beam is longitudinally accommodated in a housing having a bottom and two sidewalls situated on either side of the beam, characterized in that the tilting mechanism comprises a pivot 19 coacting with a tilt limiter 11 and disposed in the longitudinal median plane of the beam 7, through which pivot the bottom of the housing 14 is pivotally ' supported on the lifting system 10. 3. A welding apparatus according to claims 1-2, characterized in that the tilting mechanism includes means by which the horizontal axis of the tilting movement, lying in the longitudinal median plan of beam 7, is movable to adjacent the underside of the weld seam to be formed. 4. A welding apparatus according to claim 3, in which the lifting system is combined with a pressure system including a pressure hose, characterized in that there is mounted on the lifting system 10 an elongate, hollow tube 50 arranged parallel to the beam, said tube having a substantially rectangular cross-section, in the upper wall of which tube, in longitudinal direction, two parallel guide slots 49 are provided; the tube 50 incorporates two elongate, parallel supporting sections 31 extending through the guide slots, each being supported with the underside thereof in longitudinal direction on flexible pressure hoses 33 disposed on the bottom in the tube, said hoses forming the pressure system, the housing 14 being supported on the top of the supporting sections 31 by means of elongate strips 30 projecting laterally from said housing and being affixed thereto. 5. A welding apparatus according to claims 2 and 4, characterized in that the housing 14 is pivotally connected to a hood 16 swingable longitudinally over the top of the beam 7. 6. A welding apparatus according to claim 5, characterized in that the hood 16, at the side opposite the joint to be made, is fitted with a longitudinal rib 17 parallel to the beam. 7. A welding apparatus according to claims 1-6, characterized in that, as viewed in longitudinal direction, beyond the one end face of the beam, there is provided a stock length 18 of the strip 13 and beyond the other end face a reel 19 about which the finished strip can be wound, and there are mounted on either side of the beam clamping means 22,23 for the strip. 8. A welding apparatus according to claim 7, characterized in that there are provided on the top of the beam 7, in two rows, a plurality of guide pins 20 locked in the beam and projecting under spring tension above the beam, the distance between the rows being at least about equal to the width of the strip. 9. An apparatus for jointing plate-shaped materials by one¬ sided welding, comprising means for holding the plate-shaped materials during the welding operation; a horizontal backing, beam having at its top means for receiving and maintaining in position a backing strip to be kept against the underside of the weld seam to be formed; a lifting system for up-and-down movement of the horizontal beam and means for executing the one-sided welding operation, characterized in that the means for holding the plate-shaped materials during the welding operatio include a pressure element 35 arranged on the same side as the means for executing the welding operation 34 above the plate-shaped materials to be welded and movable over the weld seam to be formed synchronously with the means for executing the welding operation, said pressure element 35 including a pressure knob 43 receiving a plurality of rollers 45 adapted to be pressed on the plate edges to be welded one-sidedly and movable over the weld seam at right angles, upstream and downstream of the weld area defined by the means 34 for executing the welding operation. 10. A welding apparatus according to claim 9, characterized in that the means 34 for executing the welding operation and the pressure element 35 are combined to form a single member.

Inventors: POLAK TOM BASTIAAN, POLAK, TOM, BASTIAAN
Applicants: INT EFFICIENT PRODUCTS, INTERNATIONAL EFFICIENT PRODUCTS
Application year: 1985
Main classification: B23K37
IPC codes: B23K9