Abstract:
Applicant&#39;s invention includes an apparatus and associated method for precisely aligning two pieces of weldable material and welding the two pieces, the apparatus contains means for independently securing the two pieces of weldable material and for centering the junction of the two pieces in line with the welding electrodes.

Description:
CITATION TO PRIORITY APPLICATION 
     This patent application is a continuation application of U.S. patent application Ser. No. 08/878,394, filed Jun. 18, 1998, now U.S. Pat. No. 6,121,567 from which priority is claimed. 
    
    
     FIELD OF THE INVENTION 
     Applicant&#39;s invention relates to the joining together of two pieces of material by welding. 
     BACKGROUND INFORMATION 
     Welding is a well-known and widely-used method used to permanently join together two pieces of metal tubing or other weldable material. To accomplish a weld of high integrity, the two pieces to be joined together must be properly aligned. 
     Misalignment during welding creates discontinuities at the abutment junction of the two pieces of weldable material that can serve as havens for particle impurities. The existence of these particle “sites” is intolerable when the welding is being performed in connection with ultra-pure applications such as are common in the semiconductor industry. Moreover, misalignment can result in a leaky junction that destroys the purity of the substance flowing through the tubing and creates a potentially dangerous external environment if the substance flowing through the tubing is toxic. Thus, it is highly desirable to minimize tube misalignment when welding. 
     Maintaining proper alignment during the conventional welding process, however, is a time-consuming and difficult task. The pieces of weldable material to be aligned and welded must be clamped tightly in alignment before and during the welding process, or the pieces will tend to slip out of alignment before the weld is completed. 
     Conventional orbital weld heads do not solve this slippage problem. In an orbital welding machine, a computer-controlled welding machine works in conjunction with a weld head that also holds the two pieces of weldable material together during the welding process. The weld head is essentially comprised of a system of gears and an electrode for making the weld. The gears control the movement of the electrode as it “orbits” around the circumference of the junction between the two pieces of weldable material. Orbital welding is in great demand, especially for welding of tubing of small circumference, because of the ease in which the welding process can be controlled. Orbital welding however, does not solve the problem of misalignment. 
     To the contrary, the conventional weld head on a standard orbital welder has such little clamping surface area that proper alignment of the pieces of weldable material is often the most significant and time-consuming challenge facing the technician operating the welder. For example, welding is often performed on pieces of weldable material that are many feet in length and that may have hardware or other accessories permanently attached thereto. Because the weld head in conventional welding is typically affixed to a table or bench, the technician is sometimes required to place one end of a weldable material piece upon support blocks so that the weight of the weldable material and any attached hardware does not drag the weldable material out of alignment. 
     In addition, because of the construction of the conventional orbital weld head, the technician has an extremely limited view of the junction to be welded as he attempts to align the two pieces of weldable material to each other and position the junction of the two pieces in line with the electrode. To aid in the alignment procedure, the technician may use a “feeler” gauge such as a small screwdriver. The feeler gauge is moved by the technician over the top or side of the abutment junction, allowing the technician to determine which of the two pieces of weldable material needs to be moved to improve the alignment. Even after achieving acceptable alignment of the pieces to be welded together, the technician is also required to position the tube junction to be welded in line with the electrode, to ensure a proper weld. The manual performance of these tasks is far from ideal for applications requiring strict alignment and is very time-consuming. 
     Even if the technician is able to obtain satisfactory alignment at the start of the conventional orbital welding process, the weldable material pieces will tend to separate during the welding process, because hot spots created by the rotating electrode expand to different degrees, thereby creating a twisting effect as the electrode continues its rotation around the abutment junction. An attempt to excessively tighten the clamps on the weld head to overcome this problem usually results in the formation of clamping marks in the weldable material and may result in actual tube deformation. 
     In an attempt to solve the problem of alignment and the “twisting effect” described above, skilled welders commonly align the two pieces of weldable material and make several temporary spot welds or “tack” welds around the circumference of the abatement junction prior to final welding. Tack welds join the two pieces of weldable material together and are sufficiently strong to prevent the separation and twisting effect described above. During final welding, the tack welds merely are re-melted into the final weld. 
     Even when using tack welding, proper alignment is critical, and therefore, tack welding, by itself, does not address the problem of creating acceptable alignment in a time efficient manner. Although tack welding effectively joins two pieces together prior to performing an orbital weld and makes the orbital welding process much simpler, throughput or productivity, measured in welds per hour, is still limited by the amount of time it takes to align the pieces in preparation for the tack weld. 
     Applicant&#39;s prior invention, which is the subject of patent application Ser. No. 08/318,385, now U.S. Pat. No. 5,679,271 has addressed this alignment problem by teaching the use of a device which allows two pieces of weldable material to be precisely aligned and tack welded together. Although Applicant&#39;s prior invention is a definite improvement over the prior art, it still is not an ideal solution, because once the tack weld is completed, the technician must then spend time switching instruments to perform a full weld with a conventional orbital weld head. 
     The present invention expands and improves upon the concept taught by Applicant&#39;s prior invention, by teaching the use of a device that causes two pieces of weldable material to be precisely aligned and completely welded together, thereby eliminating the steps of tack welding and then switching instruments to perform a complete weld. 
     Thus, the present invention, by mechanizing the aligning task, has all of the benefits of a conventional orbital welder, but greatly reduces the time required to achieve tolerable alignment and eliminates the separation, twisting, and clamp mark problems associated with the use of a conventional orbital welder. 
     SUMMARY OF THE INVENTION 
     It is an objective of this invention to provide a device and method of operation for said device for aligning and welding together two pieces of weldable material. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Applicant&#39;s invention may be further understood from a description of the accompanying drawings wherein, unless otherwise specified, like reference numbers are intended to depict like components in the various views. 
     FIG.  1  through FIG. 13 depict one embodiment of this invention while FIG.  14  through FIG. 22 depict an alternative embodiment of this invention. 
     FIG. 1 is a perspective view of the alignment/welding device in the closed position; 
     FIG. 2 is an exploded view showing the arrangement of the various components that comprise a preferred embodiment of the alignment/welding device; 
     FIG. 3 is a perspective view of the alignment/welding device showing the device being closed from a fully open position to a partially closed first position, wherein the pre-lock clamping jaw is biased against the first jaw; 
     FIG. 4 is a partial cut-away view of a portion of the alignment/welding device in the closed position with weldable material present; 
     FIG. 5 is a depiction of the distance “d 1 ” which is used to measure alignment tolerances. 
     FIG. 6 is an exploded view of the electrode/rotating gear assembly of the alignment/welding device; 
     FIG. 7 is a perspective view of a portion of the alignment/welding device, illustrating the manner in which the electrodes are wired. 
     FIG. 8 is a cut-away view of a portion of the alignment/welding device with a piece of weldable material in place, illustrating the manner in which the rotating gear assembly is arranged. 
     FIG. 9 is a cross-sectional view of the top portion of the alignment/welding device that holds the weldable pieces of material when such alignment/welding device is in the fully open position. 
     FIG. 10 is a cross-sectional view of the top portion of the alignment/welding device that holds the weldable pieces of material, when the first piece of weldable material has been inserted into the alignment/welding device and the alignment/welding device is closed to a partially closed first position, securely clamping the first piece of weldable material. 
     FIG. 11 is a cross-sectional view of a portion of the alignment/welding device that holds the weldable pieces of material, when the second piece of weldable material has been inserted into the alignment/welding device to abut against the first piece of weldable material, and the alignment/welding device is closed to a fully closed, second position, securely clamping the second piece of weldable material. 
     FIG. 12 is a cross-sectional view of a portion of the alignment/welding device that holds the weldable pieces of material, after the two pieces of weldable material are securely clamped in place and the rotating gear assembly begins rotating the arcing electrodes around the abutment junction of the two pieces of weldable material, thereby welding the junction. 
     FIG. 13 is a cross-sectional view of a portion of the alignment/welding service that holds the weldable pieces of material, after the two pieces of weldable material have been welded together at the abutment junction and the alignment/welding device has been returned to a fully open position. 
     FIG.  14  through FIG. 21 depict an alternative embodiment of the alignment/welding device; 
     FIG. 14 is a perspective view of the alignment/welding device enclosed in its housing elements with the top jaws and bottom jaws in a closed position without the weldable pieces present; 
     FIG. 15 is a perspective view of the alignment/welding device with the housing elements removed exposing the motor assembly which drives the orbital welder gear assembly and the pneumatic system which controls the closing and opening of the clamping jaw system. 
     FIG. 16 is a partial cut-away view of the alignment/welding device, depicting the top clamping jaws and the bottom clamping jaws, and the spring rod which advances the top jaw  103 ; 
     FIG. 17 is a partial cut-away view of the alignment/welding device, depicting a miniature pneumatic piston which controls the centering pin  136 . The centering pin provides the means to ensure that the abutment junction of the two weldable pieces are properly aligned respect to the orbital welding mechanism. FIG. 17 also depicts the conducting strip which provides electric current path from a outside electric power supply to the orbital weld gear; 
     FIG. 18 is an exploded view showing the components that make up the one-piece orbital weld gear and the bearings against which the orbital weld gear glides during welding operation. The bearing assembly is pressed onto the bottom clamping jaw  101 . 
     FIG. 19 is a partial cut-away view of the alignment/welding device, showing the drive gear assembly which rotates the orbital meld gear during the welding operation, and the plunger type switch situated on the top clamping jaws. The switches detect the presence of the weldable material when the jaws are in a close position. 
     FIG. 20 is a partial cut-away view of the alignment/welding device, depicting the motoring assembly that drives the gear assembly which rotates the orbital weld gear, and the pneumatic cylinder which provides the linear movement necessary for the clamping operation of the top jaws; 
     FIG. 21 depicts the collet inserts with which the alignment/welding device can be adopted to align and weld multiple sizes of tube. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     In the first embodiment of the invention, referring to FIG.  1  and FIG. 3, alignment/welding device  45  preferably has a first jaw  46 , a second jaw  08  and a pre-lock clamping jaw  14 . The first jaw  46  has a substantially semi-cylindrical gap which forms a first alignment zone  47 . The second jaw  08  also has a substantially semi-cylindrical gap which forms a second alignment zone  48 . The pre-lock clamping jaw  14  also has a substantially semi-cylindrical gap which forms a third alignment zone  50 . 
     The first jaw  45  and second jaw  08  are pivotally joined together in a conventional pivot fashion, as commonly found in pliers or other similar hand tools, by using a pivot pin, bolt or similar component  49 . The pre-lock clamping jaw  14  is mounted on the pivot pin  49  alongside the second jaw  08 . As illustrated in FIG.  3  and as discussed below, when pivotally joined together and placed in the partially closed first position, the first jaw  46  aligns with and abuts against the pre-lock clamping jaw  14 , in such a manner that the first alignment zone  47 , and the third alignment zone  50  form a substantially cylindrical first section of an alignment conduit. 
     When the device is place in the fully closed second position, the first jaw  46  also is aligned with and abuts against the second jaw in such a manner that the first alignment zone  47  and the second alignment zone  48  form a substantially cylindrical second section of the alignment conduit which is substantially the same diameter as and contiguous with, the first section of the alignment conduit. 
     The diameter of the first section and second section of the alignment conduit preferably are substantially equal to the diameter of the pieces of weldable material to be welded together. 
     Referring to FIG. 2, tension rod  31  connects the pre-lock clamping jaw  14  to the second jaw  08  and pivotally advances pre-lock clamping jaw  14  so that the pre-lock clamping jaw  14  leads the second jaw  08  when the device is being closed, as shown in FIG.  3 . The device  45  is closed to a first position by actuating a double acting/single rod pneumatic cylinder  37  (FIG. 2) or similar device. In place of a pneumatic cylinder, other well-known methods for closing the device can be used, such as a ratcheting gear or even manual pressure applied by the technician. 
     In this partially-closed first position, the pre-lock clamping jaw  14  abuts against the first jaw  46  as illustrated in FIG.  3  and the first section of the alignment conduit is formed. As device  45  is fully closed to the second/final position, the second jaw also abuts against the first jaw and the second section of the alignment conduit is formed. In the fully closed second position, the second jaw  8  and the pre-lock clamping jaw  14  are firmly positioned against the first jaw  46 . 
     This mechanism allows a first piece of weldable material  51  and a second weldable material piece  52  to be secured into device  45  independently of one another. 
     The manner in which the device  45  is used to align and weld two pieces of weldable material is best demonstrated by referring to FIGS. 9-12. As illustrated in FIG. 9, the technician places the first piece of weldable material  51  between the first jaw  46  and pre-lock clamping jaw  14 , abutting against the retractable centering pin  41 , located in the first jaw. As shown in FIG. 6, the centering pin is preferably spring-loaded and adjusted with a set screw. The centering pin is positioned such that it extends into the alignment conduit and is in the same plane of spatial orientation as the plurality of electrodes which also extend into the alignment conduit  47 . The purpose of the centering pin is to center the abutment junction of the two pieces of weldable material directly in line with the electrodes and, therefore, any mechanism that would serve this purpose, would suffice. 
     As illustrated in FIG. 10, as the device  45  is closed to the partially-closed first position, the pre-lock clamping jaw  14  makes contact with the first jaw  46 , thereby firmly securing the first weldable material piece  51  in the first section of the alignment conduit, with the first terminus of the first piece of weldable material being located in the same plane of spatial orientation as the electrodes  40 . As illustrated in FIG.  10  and FIG. 11, the technician then places the second piece of weldable material  52  between the first jaw  46  and second jaw  08 , with the terminus of said second piece abutting the first terminus of the first weldable material piece  51 . This action will cause the centering pin  41  to be depressed. In this manner, the two pieces of weldable material will contact each other and form an abutment junction in substantially the same plane of spatial orientation as the electrodes  40  surrounding the alignment conduit. By actuating the pneumatic cylinder  37  to the second/final position, the second jaw  08  contacts the first jaw  46  and firmly secures the second piece of weldable material  52  within the second alignment conduit. 
     Because the first section and second section of the alignment conduit are substantially the same diameter and are substantially contiguous when device  45  is in the fully closed position, the first weldable material piece  51  and the second weldable material piece  52  will be in strict alignment with each other. Alignment tolerances of 10% or better can be achieved by the device  45  where the alignment tolerance equals the distance by which the weldable material pieces deviate from perfect alignment, divided by the diameter of the weldable material pieces. The distance by which the weldable material pieces deviate from perfect alignment is shown as “d 1 ” in FIG.  5  and is measured at the largest exposed edge of first weldable material piece  51  at the junction with second weldable material piece  52 . 
     When the device  45  is in a fully closed position, the first weldable material piece  51  and the second weldable material piece  52  are in place and the junction of these two pieces are in substantially the same plane of spatial orientation as the electrodes  40 . Furthermore, the first weldable material piece  51  and the second weldable material piece  52  are in alignment with each other. With the first weldable material piece  51  and the second weldable material piece  52  thus securely clamped into place, device  45  can now be used for the weld process. 
     Referring to FIG. 7, argon gas from an external source (not shown) will flow into purge lines  55  via an external hose (not shown). The weld process is then initiated by depressing switch  44  which is depicted in FIG.  1 . Referring to FIG.  6  and FIG. 8, the external welder (not shown) will supply an electric charge via wires  56  (FIG. 7) to the contacts  39  which will then cause electrodes  40  to arc to the abutment junction, thereby beginning the weld. An electric motor  29  or similar device then rotates u-joint  28 , which, in turn, rotates the primary drive gear  25 . As shown in FIG.  6  and FIG. 8, the primary drive gear  25  then rotates the secondary drive gear  23 , thereby rotating insulating gears  09  and  16  a total of approximately 130 degrees. As illustrated in FIG. 12, the rotation of the insulating gears  09  and  16  allows the electrodes  40  to revolve around the abutment junction, thereby creating a complete weld of the abutment junction. After the weld process is complete, pressure is applied to the return side of the pneumatic cylinder  37  (FIG.  1 ), thereby releasing the pre-lock clamping jaw  14  and second jaw and allowing the fused weldable material piece to be removed from the device  45  as illustrated in FIG.  13 . 
     The alternative embodiment as depicted in FIG. 14 further improves upon the first embodiment in several aspects. 
     First, the clamping jaws in the alternative embodiment are designed in such a way that a collet of highly precise dimension fits securely into the clamping jaws for gripping the weldable material during the welding operation. The precision collet not only grips the weldable material more securely but also significantly enhances the precision of alignment of the two pieces of weldable material. In addition, the easily interchangeable collet can be made of different inner sizes and dimensions to accommodate various weldable material of different outer dimensions and therefore significantly enhances the versatility of the alignment/welding device. 
     Second, the alternative arrangement of the driving gear assembly and the forty-five degree bearings packed next to the one-piece welding gear substantially reduced the outer dimension of the welding head assembly of the alignment/welding device. The small welding head allows the welding operation in very tight spaces. This is highly desirable in situations often found in typical semiconductor manufacturing facilities where the welding must be performed on one of many tubings closely spaced. 
     Referring to FIG. 14, the alignment/welding device  100  is shown in its enclosed form, housed in cover  119  and  120 . In FIG. 15, the cover pieces  119  and  120  are removed, showing the pneumatic cylinder and the linkage assembly that bias the top clamping jaws  103  and  104  (see FIG.  16 ), also shown in FIG. 15 is the motor assembly that drives the gear assembly that rotates the one-piece weld gear. 
     In this embodiment, the alignment/welding device is comprised of four clamping jaws pivot by a pivot element  107 , as shown in FIG.  16 . At the bottom, jaw  102  acts as a cover for the bottom jaw  101  and also provides one of four clamping jaw surfaces. At the top, a clamping jaw  102 , corresponding to the pre-lock clamping jaw  14  in the first mode of embodiment, is advanced with respect to top clamping jaw  104  by a spring rod  105 . The tension of the spring rod  105  can be adjusted through an adjustment block  106  that is attached to a top clamping jaw  101 . Pivot element  107  functions similarly to the pivot pin  49  in the first mode of embodiment. 
     In this embodiment, the welding is performed with a one-piece weld gear  129 , as in FIG. 17, which holds the tungsten welding electrodes  130 . The one-piece weld gear is made of ceramic material. The weld gear may be made of conventional metallic material but insulation coating would be necessary. Ceramic provides not only excellent electrical insulation necessary for the welding operation but also provides excellent heat resistance. 
     The electric current path is provided to the tungsten electrodes  130  through an electric strip element  128 , as shown in FIG. 18, which is secured to the ceramic weld gear  129 . Element  128  makes electrical contact with a strip element  127  which is connected to an outside electrical power supply (not shown) through a conductive strip element  122  as shown in FIG.  17 . Conductive strip  127  is insulated from the clamping body by a ceramic insulator spacer element  126 . The one-piece weld gear is complete with a wavy washer element  123  in FIG.  18 . The wavy washer element  123  provides spring pressure to the ceramic insulator spacer element  126 . 
     The clamping operation is a two-step process, similar to the first embodiment. As shown in FIG. 20, a pneumatic cylinder  114  drives the top clamping jaws  103  and  104 . This pneumatic cylinder  114  has a three-step actuation. When the clamping system is in its fully open position, air pressure is supplied to a miniature pneumatic cylinder  121 , in FIG.  17 . The miniature pneumatic cylinder  121  extends the centering pin  136  into the substantially semi-cylindrical clamping zone formed by the bottom clamping jaws. The function of the centering pin  136  is similar to that of the centering pin  41  in the first embodiment. When the first piece of the weldable material is fully extended into the bottom clamping jaw  102 , the terminus of the weldable material abuts against the centering pin  136  which is in the same spatial plane formed by the plurality of welding electrodes  130 . At the first actuated position of the pneumatic cylinder  114 , the top clamping jaw  103 , biased by the spring rod  105 , is advanced to its lock position, securely locks the fist piece of a weldable material between the top clamping jaw  103  and the bottom clamping jaw  102 . At the second actuated position of the pneumatic cylinder  114 , the centering pin  136  is fully extracted from the clamping zone, ready to receive the second piece of the weldable material. At the third actuated position of the pneumatic cylinder, the top clamping jaw  104  is biased by the linkage assembly of  109 ,  118 ,  117 ,  116 , and  115  to its lock position, thus securely clamps the second piece of weldable material that is abutted against the first piece of weldable material. 
     When both pieces of weldable material are securely clamped by the clamping jaws  102 ,  103 ,  101 , and  104 , two plunger type electrical switches  105  in FIG. 18, located in the top clamping jaws  103  and  104  are activated. The activation of the switches signal the presence of the weldable material and the readiness for the commence of welding operation. 
     The welding operation involves both the rotation of the ceramic weld gear  129  and the flow of electrical current to the weld electrodes  130  in FIG.  18  and FIG.  19 . 
     The ceramic weld gear  129  is driven by a electric motor  112 , as shown in FIG. 20, through a drive gear assembly  124 , as shown in FIG.  19 . The drive motor system is comprised of an electric motor  112 , a mounting bracket  111 , a universal  110  which is used to correct for any misalignment between the motor  112  and the drive shaft  108  which is coupled to the drive gear assembly  124 , as shown in FIG.  19 . The rotation of the motor is further measured by an encoder  113  that provides control mechanism. 
     The alignment of the ceramic weld gear to the junction of the two pieces of weldable material is further enhanced by resting the ceramic weld gear on a bed of bearings  132  pressed onto the bottom clamping jaw  101 , as shown in FIG.  18 . The bearings  132  are arranged in an alternating 45 degree circular pattern. Each bearing  132  is secured onto the bearing pin  134  by a washer element  131  on the one side and a washer element  133  on the other side such that the inner race of the bearing is resting while the outer race can rotate. 
     The versatility of the alignment/weld device is further enhanced by incorporating collet inserts  135 , as in FIG. 21, onto the clamping jaws  101 ,  102 ,  103 , and  104 , as shown in FIG.  21 . By selecting collet inserts of different inner dimensions, the alignment/weld device will be easily adopted to welding material of different circumferences. 
     Although the invention has been described with reference to specific embodiments, this description is not meant to be construed in a limited sense. Various modifications of the disclosed embodiments, as well as alternative embodiments of the inventions will become apparent to persons skilled in the art upon the reference to the description of the invention. It is, therefore, contemplated that the appended claims will cover such modifications that fall within the scope of the invention.