Патент USA US2404620код для вставки
July 23, 1946. J. H. COOPER 2,404,62Q CONTROL OF FLASH WELDING Filed ‘ Feb.» 1, 1944 2- SheQ'tsLSheet 1 Ll L 30 \LVVVVV » VVVVVV JOSEPH H. COOPER 3% f2??? - ?lm/wag July 23, 1946. , J. H. COOPER 2,404,620 CON‘II‘ROL OF FLASH WELDING ‘ Filed Feb. 1, 1944 2 Sheets-Sheet 2 COOPER 2,404,620 Patented July 23, 1946 UNITED STATES PATENT OFFICE 2,404,620 CONTROL OF FLASHvWELDING Joseph H. Cooper, Warren, Ohio, assignor to The Taylor-Win?eld Corporation, Warren, Ohio, a corporation of Ohio Application February 1, 1944, vSerial No. 520,582 10 Claims. (Cl. 219-4) 2 1 This invention relates to electric ?ash welding and more particularly to methods and devices for length of the are or ?ash itself. effecting and controlling during the welding cycle the condition of the arc either the voltage across the are or the current ?owing ‘in either thepri mary Winding or the secondary winding or both the movement relative to each other of the work pieces to be joined. To arrivelat ' reference conditions variable in accordance with The methods and devices these windings of the welding transformer em--, ployed is measured and through suitable relay mechanisms, preferably of the electronic type, the ing cycle, it being understood that normally the relative movement of the work pieces is continu complete ?ash-butt welding cycle comprises a ?rst period in which the work pieces are brought 10 ously controlled in accordance with variations in the reference condition or conditions thus ob together with current passing ‘through them to preheat the edges, the second or ?ashing period tained. A further object of the invention is the provi during which the edges are spaced apart and an sion of an improved arrangement for automati electric are maintained between them, and the cally controlling the relative movement of the ?nal act of jamming the edges together to upset work pieces during the ?ashing period of a ?ash the edges and effect 'a uniform cohesive Weld butt welding cycle together withan improved ar throughout the extent of the section. ‘ As the rangement for shifting the control of .the, rela? ?ashing progresses the metal of the edges is burnt tive movement of the work pieces from manual or blown off and it becomes necessary to move herein disclosed are particularly advantageous in connection with the ?ashing period of the weld to automatic operation or vice versa as desired. the work pieces toward each other to ‘maintain :. Another object of the. invention is the .provi the arcing or ?ashing. sion, in an electric ?ash-butt welding apparatus, of arr-improved arrangement for manually con. trolling the relative movement of the work pieces Heretofore the moving of ‘the work pieces to ward each other during the ?ashing period has been accomplished by suitable apparatus under during the Welding cycle including‘ the ?ashing period thereof. either manual control or automatic control of the type in which the relative movement is regulated according to a predetermined time-position pat tern. This latter mode of operation is usually accomplished by employing a moving. cam for controlling a hydraulic valve in metering the flow of hydraulic ?uid to the Work moving means, the cam'being made up of a multiplicity of separable segments which can Ice-suitably rearranged to effect different cam contours’. ‘The manual method of control requires the constant attention of a highly skilled operator in-order that the re quired degree of consistency and uniformity may be attained in the welding while experience has shown'that optimum'?ashing action cannot al ways be obtained by predetermined settings of A still further object of .the invention is the provision, in electric ?ash-butt Welding appara tus, of an improved arrangement for manually controlling the relative movement ‘of. the work pieces during the welding cycle including the ?ashing period thereof together with an improved arrangement for shifting from such manual con trol to an automatic control at the will .of the operator. The above and other objects and advantages of the invention will be-rmorelfully understood upon consideration of the following detailed speci?cation and the accompanying drawings wherein there isspeci?cally disclosedcertain pre ferred embodiments of the invention. In the drawings: Figure 1 is a schematic representation of elec tric ?ash welding apparatusconstructed in ac cordance with‘ the principles of the invention; the controlling cam in an automatic system. It is accordingly the primary object of the in» vention to provide an improved arrangement, in an electric ?ash welding machine, for controlling the‘ movement of ‘the work pieces‘ toward each other during the ?ashing period of the complete Welding cycle whereby optimum ?ashing condi tions are automatically maintained irrespective of the presence of the various factors which ren . and Figure 2 is‘a schematicrepresentation of a modi?ed part of the apparatusof Figure 1. The apparatus illustrated includes anormally der automatic systems heretofore devised. for the 50 fixed platen l8 and a movable platen II of an purpose Wholly unreliable.‘ In accordance with electric ?ash Welding machine and, in accord the present invention, this general object of the invention is accomplished by controlling the rela ance with usual practice, ‘these platens are each arranged to carry electrodes [2 which are opera tive movement of the Work pieces directly in ac cordance' with the instantaneous condition 'or together to the respective platens. whereby the tive to clamp the two work pieces to bewelded anoaééo 2; 4 work pieces will have relative movement in ac cordance with‘ relative movement between the platens. The electrodes also conduct welding current to the work pieces and for this purpose primary winding of the welding transformer I3. are connected to the terminals of the secondary winding of the welding transformer 13. The pri mary winding of welding transformer i3 is ar in a manner now to be described. I utilize the instantaneous values of the poten tials developed across resistances 34 and 35 to control the operation of the valves 23F and 28B Deriving energy from the current supply line CLI is a recti?er 36 the output of which is smoothed out at 37 to develop a uniform poten ranged to be connected to a suitable source com tial across resistor 38, which resistor is provided prising the line conductors LI and L2 through a suitable circuit controlling device 14. While this 10 with sliding contacts A and B and connected across the positive‘ terminal of the resistor 38 device I4 is shown in the drawings, for simplicity and the contact 13 thereof is a grid-controlled of illustration, as being simply a switch it will be space discharge device 39 and a load resistor 48 understood that in actual practice such device in series. Resistor 34 is in the grid-controlled cir will ordinarily be of the current modulating type under either manual or timed automatic control. 15 cuit for tube 39 through contact B, conductor 4|, resistor 35, and conductor 42 to the control grid Movable platen ll of the welding machine is of tube 353. Thus when no current is flowing arranged to be moved toward and away from the through the primary of the welding transformer ?xed platen Ml by a hydraulic cylinder 15 under is tube 39 is held non-conducting by the nega control of a follow-up valve l5. As such, this valve has a movable element which is connected 20 tive bias furnished by the resistance 38 from point B to the negative terminal thereof but upon the to the movable platen by means of a link El and appearance of a predetermined opposing poten a coacting movable element which is moved upon tial across resistor at as caused by the flow of cur rent to the primary of transformer l3 the tube able platen driving means generally may be sim~ ilar to that shown more in detail in the copencling 25 39 begins to conduct to develop across resistor 40 a potential which in a circuit now to be described application of C. E. Coates, Serial No. 431361;, rotation of shaft l8. Valve It; as well as the mov ?led February 18, 1942, for “Hydraulic butt welder contro ,” now Patent No. 2,373,226, dated April 10, 1945. Shaft I8 is coupled with the output shaft of a direct current motor 19 through a suitable speed reducing mechanism 2%} and, for a purpose to be later described, an operating arm 21 is also keyed to the shaft 18. Motor i9 is provided with a ?eld Winding 22 which may be connected to any suitable source of uni-directional current and an armature 23 which rotates in one or the other direction de is in opposition to the potential appearing be tween contact A of resistor 38 and the positive terminal thereof. This latter potential is utilized to hold the valve 23F normally conducting, the control circuit for valve 28F being traceable from the cathode thereof through conductor 43, con tact A, resistor 40, conductor 44, the secondary of a biasing transformer 45 to the control grid of valve 28F. The alternating component fur nished this circuit by the transformer 45 is ?xed at a 90° phase angle with respect to the anode cathode voltage appearing across the valve 281?. Therefore it will be apparent that valve 28F is pending on the direction of current flow through it. Armature current for motor 19 is derived from a control current supply line CLl through con 40 normally fully conductive tending to rotate motor 19 and the motor connected element of the con ductor 24, a suitable current controlling device 25, conductor 25, armature Z3, conductor 2?, dis trol valve It in a direction to cause movement the strength of current ?owing in the primary winding of the welding transformer may be taken ' predetermined potential across resistor 35 the tube of platen H toward platen Iil. charge devices 28F and 28R connected in inverse A control system similar, in general, to the parallel and conductor 29 back to line CH. The discharge devices 28F and 28R are preferably of 45 above is provided to control conduction in valve 2BR in response to the instantaneous potential the grid controlled gaseous type each having a developed across resistor 35 although the effect is circuit connected to its control grid for determin reversed in that a heavier welding current re ing the point on the respective positive and nega sults in increased, rather than decreased, con tive half wave cycles at which conduction in the respective devices is initiated- In this manner 50 duction in the valve 28R. Thus I provide a recti her 415 deriving energy from the supply line CLI the direction and intensity of the current flow and developing its output, after smoothing out through the armature 23 of themotor l9 may be at 41, across a resistor 48 which is provided inter readily controlled. Thus if, for example, the tube mediate its terminals with sliding contacts C and 28F is regulated to start conducting earlier on its D. A controlled space discharge device 49 and a half Wave than the tube 28R the resultant com load resistor 50 is connected across the positive ponent of current will flow through the armature terminal and the contact D of the resistor 48 and 23 insuch manner as to cause the armature to the control circuit for tube 49 is traceable from rotate in a direction to move the platen H to the cathode thereof through contact D, conductor ward the platen I3. If the ?ring point of tube 28F is further advanced motor l9 and conse 60 5|, resistor 35, and conductor 52 to the control grid of tube 49. Again a portion of the potential quently platen l l is speed up. across resistor 48 is utilized to hold the tube 49 As explained above, the instantaneous value of non-conducting and upon the appearance of a as an indication of the condition of the ?ashing 65 49 begins to conduct to pass current in proportion to the value of the potential developed across re during the ?ashing period since if the arc is too sistor 35. As the tube 49 conducts it develops short for optimum operation an excessive current across resistor 50 a potential which, in the circuit is being drawn While if the arc is lengthened to now to be described, is in opposition to the po the point where extinguishment becomes prob able the current is very materially decreased. 70 tential across that portion of the resistor 49 which is intermediate the positive terminal thereof and Therefore I may employ current transformers 3i! the contact C‘. This last mentioned circuit is the and 3! the outputs of which are recti?ed at 32 control circuit for valve 28R which is traceable and 33, respectively to develop across resistances from the cathode thereof through conductor 53, 34 and 35, respectively, potentials which are pro portional to the strength of current ?owing in the 75 resistor 50, resistor 48 to contact C, conductor 54, 9,404,626 5 the secondary of a grid biasing transformer‘ 55, conductor 56 to the control element of valve 28R. While the alternating component furnished this circuit by the transformer 55 is displaced by 90° in phase’ with respect to the anode-cathode volt 6 I may provide an energizing circuit ‘for solenoid 6H which includes a current source GI and a switch 62 which is closed upon the arm 2| reaching a predetermined advanced position. Since arm 21 is keyed to one of the coasting movable elements in follow-up valve l6 switch 62 will not be closed until the desired amount of metal is burned off ponent applied between the positive terminal and the edges of the Work pieces which are‘ to be contact 0 of resistor 128 is sui‘?cient to hold the joined. It ‘should also be understood that the arm valve 28 normally non-conducting. However, when tube 49 begins to conduct the opposing di 10 2| may be employed to open, either directly or through time delay apparatus, the circuit con rect potential supplied by resistor 50 will cause trolling device [4. valve 28R to conduct current in an amount de Under certain conditions it may be desirable termined by the value of the potential developed to provide for the regulation of the movement across resistor 35. It should now be apparent that upon the work 15 of the movable platen either manually or auto matically‘ at the will of the operator and in Fig pieces being clamped by the electrodes 12 and the ure- 2 I have shown a portion of» the circuit of closure of the circuit controlling devices 14 and Figure 1 in’ modi?ed form whereby the machine 25 motor 19 will operate to advance platen H may be readil-y‘put» on manual or automatic oper to bring the work pieces together and upon such ation. Referring to Figure 2, I provide a mul short-circuiting of the welding transformer very tiple poled switch or relay structure shown sche heavy current will be drawn by the primary matically at- 65 which is operative, when its oper thereof which condition will be at once sensed ating elementis moved to the left as viewed in by the transformers 3B and 3| and the potentials Figure 2, to connect the outputs of recti?ers 32 consequently appearing across resistor 34 and 35 and 33 across the resistors 3K1 and 35 in the same will operate to decrease or terminate conduction manner as in Figure 1 thus providing for wholly in valve 28F while initiating the increasing con automatic operation. When the‘ switch 65 is duction in valve 28R. Depending on the nature moved to the right the secondaries of transform and character of the work, the voltages applied, ers 39- and 3| are connected across the resistors and other factors, the movable platen II will age across the valve 28R the negative direct com either stop or back up slightly but in either case 30 34 and 35-, respectively, through the discharge devices 66 and 61, respectively, which are prefer the arcing or flashing between the work pieces will ably of the grid controlled gaseous type. Con be initiated and maintained because the balance duction in tube 66 is controlled by an impulsing of the system is so adjusted for the particular transformer 68 the primary of which is connected work at hand that the interval between the pieces will be maintained to produce optimum flashing. It the arc lengthens to the point where it is about to become extinguished or if it is extinguished the current in primaries of the transformers 3i] and 3| decreases to such value that valve 28F passes much more current than valve 28R so that motor l 9 rotates in a direction to again move the platen I I toward the platen In. In this manner the work pieces in the welding machine are automatically moved relative to each other in such manner that optimum ?ashing between the pieces is main tained. Under certain conditions it may be desirable to back off the platen ll under manual control during the time that the switch 25 and the cir across the supply line Ll, L2 through the resist ance shown and, similarly conduction in tube 61 is ‘controlled by an impulsing transformer 69, the primary of which is also connected across the line Ll, L2 through the resistance shown. In parallel with the primary of transformer 68 is a variable reactor having a coil 10‘ which is ?xed physically with respect to normally stationary parts of the welding machine and a soft iron core ll arranged to be moved further into the coil 10 upon movement of the platen ll toward the platen 10. As the core 'Il moves toward the center of the coil 10' the reactance of the coil-10 diminishes thereby bringing the output of the transformer 63 closer in phase with the anode cuits are otherwise conditioned for automatic op 50 cathode voltage across tube 66 causing this tube to conduct more current which is induced in the eration. For this purpose I may provide a double secondary of transformer 33 upon the flow of cur poled switch 51 one contactor of which connects of valve 28F highly negative thus extinguishing rent through the primary of transformer I3. In parallel with the primary of transformer 69 is a platen at the start of the complete Welding cycle. For -controlling according to the latter method transformer primary circuit the magnetizing cur rent flowing in this circuit furnishes suf?cient contact B of resistor 38 to lead 44 to drive the grid this valve. The other contactor of switch 51 55 variable reactor having a ?xed coil 12 and a soft iron core 13 which is arranged to be moved connects lead 53 with contact D of ‘resistor 48 toward and away from the center of coil 12 by through a variable resistance 58 to drive the grid a manually engageable lever 14 and it will be of valve 28R highly positive thus conditioning this understood that as the lever is moved to the valve for maximum conduction. Upon completion of the ?ashing phase of the 60 left, bringing core 13 closer toward the center of coil 12 the value of the reactance of coil 12 will welding cycle it is necessary that the work pieces diminish thereby bringing the output of trans be rapidly brought into pressure engagement with former 69 more closely in phase with the anode each other and for this purpose I may employ a cathode voltage across tube 61 to increase con dumping valve 58 also connected to the cylinder l5 and operative, when its operating solenoid 60 65 duction in this tube. The mechanical linkages and the parameters of the electrical circuits are’ is energized, to rapidly conduct a large volume of so adjusted that with the platen ll fully re hydraulic fluid under pressure to the outer end moved from the platen Ill and the lever 14 also of cylinder [5 all in a manner more fully ex removed to its right position the valves 28F and plained in the above mentioned co-pending ap 26R conduct equal current so that the armature plication. The energization of solenoid 69 may of motor 19 is locked and the mechanical parts be either time-controlled or controlled in accord of the machine are at rest. It should be noted ance with the position attained by the movable that upon closing of the device M in the welding platen as related to the initial position of the 2,404,620 7 8 energy for translation through transformers 30 and 3| and tubes 66 and 61 to develop su?icient potentials across resistors 34 and 35 to effect this mode of operation, it being understood that re sitory electrical condition in the work circuit in control of the relative conduction in said devices whereby the speed and direction of movement position of the parts we may assume that the core 13 is in the center of coil 12 while the core 3. Apparatus according to claim 1 further in cluding means responsive to the strength of cur ‘H is o? to the right of the center of the coil l O 10. Now if the lever 14 is moved to the left the reactance of coil 12 is diminished decreasing the potential across resistor 35 and consequently decreasing the current being passed by valve 28R. The forward component of the current rent ?owing through said transformer, control of said movable control element of said follow sistors 34 and 35 of Figure 2 are connected into 07 up valve is controlled so as to effect automatically the current modulating circuits for armature 23 optimum ?ashing between adjacent edges of said in the manner shown in Figure 1. In the stated work pieces. then furnished armature 23 overbalances and the armature rotates in the proper direction to move platen II to the left. Upon such move ment reactance of coil 10 is diminished, the ulti circuits intermediate said responsive means and the control elements of said devices, said con trol circuits being operative upon increase of transformer current to increase conduction in one of said devices while decreasing conduction in the other and vice versa whereby optimum ?ashing between adjacent edges of said work pieces may be automatically maintained. mate effect of which is to diminish the current , 4. Apparatus according to claim 1 further in cluding means responsive to the value of a tran sitory electrical condition in the work circuit in control of the relative conduction in said devices passed by valve 28F and in this manner a balance may be maintained whereby the movement of the platen H follows precisely the movement of the whereby optimum ?ashing between adjacent lever 74. By providing switch 65 with an operat edges of the work pieces may be automatically ing coil the operator may at any time either be 25 maintained, a manual control lever, means to fore, during or after the actual welding cycle establish an electrical condition variable in ac transfer the control of the movement of the cordance with changes of position of said lever, platen II from “manual” to “automatic” or vice and switching means operative to effect utiliza versa. For example, it is contemplated that a tion of either said value or said condition at the control button for such actuating coil may be will of the operator to control the relative con mounted directly on the lever 14 so that at any duction in said devices. time upon release of the lever and button the con 5. In electric ?ash-butt welding apparatus trol will automatically shift to “automatic.” having means to move the work pieces toward This is advantageous since in many cases it is and away from each other as well as means to desirable to preheat and initiate ?ashing under 35 conduct welding current thereto, the combina manual control after which automatic control tion of means to control said means to move of the ?ashing would normally be more desir able. comprising a control element the direction and speed of movement of which determines the di While in the embodiments speci?cally described rection and speed of the relative movement be above I have taken as the controlling reference tween said work pieces, a direct current motor condition the strength of current ?owing in the for driving said control element, an electric valve primary winding of the welding transformer it for controlling the flow of current through the should be understood that with suitable and obvi armature in one direction, a second electric valve ous modi?cation the condition may as well be a for controlling the ?ow of current through said measure of the voltage appearing across the work 1, armature in the opposite direction, and means pieces or a measure of the current ?owing in to control the conduction in said ?rst valve with the secondary winding of the welding transform respect to the conduction in said second valve er or any combination of these three factors. whereby the direction and intensity of the cur The above speci?cally described embodiments - rent ?owing through said armature is controlled. of the invention should be considered as illus- . 6. Apparatus according to claim 5 further characterized in that said means to control the relative conduction in said valves comprises means responsive to the value of a transitory electrical condition in the work circuit whereby trative only as obviously many changes may be made therein without departing from the spirit or scope of the invention. Reference should therefore be had to the appended claims in de termining the scope of the invention. optimum ?ashing between adjacent edges of said Work .pieces may be automatically main What I claim is: tained. 1. In electric-?ash-butt welding apparatus '7. Apparatus according to claim 5 further having a welding power transformer, a normally ?xed platen and a movable platen adapted to characterized in that said valves are of the con hold work pieces, a hydraulic cylinder to move 60 trolled gaseous type connected in inverse par said movable platen, and a follow-up valve in allel in a current supply circuit interconnecting control of the flow of ?uid under pressure to an alternating current source and said arma opposite ends of said cylinder; the combination ture, said means to control the relative conduc of means to move a movable control element of tion in said valves comprising means applying said follow-up valve comprising a direct cur rent motor, and means to energize the arma alternating grid potentials to the control ele ments of said valves, and means applying con ture of said motor in alternate directions and trolled direct current potential components to with controlled intensity comprising a source of the control elements of said valves. alternating current and a circuit interconnect 8. Apparatus according to claim 5 further ing said source and armature, said circuit in 70 characterized in that said valves are of the con cluding in series therein a pair of controlled elec trolled gaseous type connected in inverse par tric discharge devices connected in inverse par allel in a current supply circuit interconnecting allel relation. ' 2. Apparatus according to claim 1 further in cluding means responsive to the value of a tran an alternating current source and said arma ture, said means to control the relative conduc 75 tion in said valves comprising means applying , 2,404,620 9 alternating grid potentials to the control ele ments of said valves, and means applying con trolled direct current potential components to the control elements of said valves, the values of said direct current components of biasing po tentials being variable in accordance with the value of a transitory electrical condition in the work circuit whereby optimum flashing between adjacent edges of said Work pieces may be au tomatically maintained. 9. In electric ?ash-butt welding apparatus 10 establishing an electrical condition variable in accordance with variations in the interval be tween said work pieces, a manually engageable element, and means to control the energization of the other of said devices comprising means establishing an electrical condition variable in accordance with variations in the position of said element. 10. Apparatus according to claim 9 further characterized in that said ?rst and second men tioned electrical devices each comprises a con trolled gaseous discharge device connected in having means to retain the work pieces to be inverse parallel for controlling the ?ow of cur joined and to conduct current thereto as well rent from an alternating current source, said as means to move said pieces toward and away from each other, the combination of an electri 15 ?rst and second mentioned means to control comprising means to condition said devices for cal device in control of said means to move conduction at variable points during the re operative when energized to effect a force tend spective half cycles of anode-cathode voltage ing to move said pieces away from each other, a applied across the respective devices by said second electrical device operative when ener source. gized to effect a force tending to move said pieces toward each other, means to control the energi zation of one of said devices comprising means JOSEPH H. COOPER.