Abstract:
A carriage for guiding a cutting, beveling or welding torch on the surface of a metal work piece has a chassis which is transported along a main path on the work piece by a magnetic wheel assembly driven by a reversible motor mounted on the chassis. A rack and pinion assembly mounted on the chassis is driven by another reversible motor mounted on the chassis to transport a torch holder along a path perpendicular to the main path. A remote controller electrically connected to the drive motors is manually operable to simultaneously permit forward or backward transport of the chassis, right or left transport of the holder and variation of the angular velocity of the chassis motor and the rack and pinion motor so as to accurately trace any cutting path on the work piece with the torch. The elevation of the torch above the work piece and the angle of incidence between the torch and the work piece are manually adjustable.

Description:
This application is a continuation of application Ser. No. 09/576,340 filed on May 22, 2000, now abandoned. 
    
    
     BACKGROUND OF THE INVENTION 
     This invention relates generally to cutting, beveling and welding torches for carbon steel workpieces and more particularly concerns carriages for transporting and guiding such torches along a desired path on a workpiece. 
     Known torch carriages permit variation of the direction and speed of travel of only the carriage along the workpiece. Thus, the torch can only follow the carriage path and any variation in the work path from the carriage path can be accounted for only by reorienting the carriage on the workpiece. It is not presently possible to trace any desired path on a workpiece in a single remotely controlled operation of the carriage. 
     It is, therefore, an object of this invention to provide a torch carriage which enables an operator to accurately trace the torch along any narrow path on a workpiece. It is also an object of this invention to provide a torch carriage which enables an operator to remotely guide the travel of the torch along the desired workpiece path. An additional object of this invention is to provide a torch carriage which enables an operator to control the direction of travel of the torch in two dimensions. Still another objection of this invention is to provide a torch carriage which enables an operator to control the speed of travel of the torch in a direction transverse to the direction of the carriage. Another object of this invention is to provide a torch carriage capable of performing on vertically or horizontally oriented flat or arcuate workpieces. A further object of this invention is to provide a torch carriage which is capable of accurately tracing a narrow linear or nonlinear path on the outside or inside wall of a tubular workpiece. Yet another object of this invention is to provide a torch carriage which is firmly magnetically engaged with the workpiece regardless of its shape or orientation. Still another object of this invention is to provide a torch carriage which is easily disengaged from magnetic engagement with the workpiece. A further object of this invention is to provide a torch carriage which enables an operator to adjust the elevation or distance of the torch from the workpiece surface. Yet another object of this invention is to provide a torch carriage which enables an operator to adjust the angle of the torch with respect to the workpiece suitable so as to create a “bevel” on the workpiece. And it is an object of this invention to provide a torch carrier which permits selection of the transverse carriage and torch speeds so as to provide a miter angle on a workpiece. 
     SUMMARY OF THE INVENTION 
     In accordance with the invention, a carriage is provided for guiding a cutting, beveling or welding torch on the surface of a metal workpiece. The carriage has a chassis which is transported along a main path on the workpiece by a wheel assembly. The wheels of the assembly magnetically maintain engagement with the workpiece. A reversible motor mounted on the chassis drives the wheels so as to transport the chassis forward or backward along the main path. A rack and pinion assembly mounted on the chassis transports a torch holder along a path perpendicular to the main path. Another reversible motor mounted on the chassis drives the pinion of the rack and pinion assembly so as to transport the holder to the left or to the right along the perpendicular path. A remote controller electrically connected to the drive motors is manually operable to simultaneously permit forward or backward transport of the chassis and right or left transport of the holder, respectively, so as to accurately trace any cutting path on the workpiece with the torch. The remote controller has one toggle switch for selecting from the forward, off and backward operating conditions of the wheel assembly motor and another toggle switch for selecting from the left, off and right operating conditions of the rack and pinion motor. The controller is further manually operable to vary the angular velocity of the chassis motor and the rack and pinion motor, for example, by use of rheostats electrically connected to the motors. One mechanism, such as another rack and pinion assembly, is provided for manually adjusting the elevation of the torch above the workpiece and another mechanism is provided for manually adjusting the angle of incidence between the torch and the workpiece. A lift assembly permits manual disengagement of the magnetic wheel assembly from the workpiece. In a preferred lift assembly, an axle is journalled on the chassis for rotation about a longitudinal axis perpendicular to the main path of the chassis and a lever extends radially from the axle for a distance sufficient to permit engagement of the lever with the workpiece. A knob or crank on the lever facilitates manual rotation of the axle to engage the lever against the workpiece and pry the wheels from the workpiece. In order to limit deflection of the torch transport rack in relation to the chassis, at least two cams are spaced apart and rotatable to take up slack between the chassis and the torch transport rack. Set screws lock the cams in their selected angular position. A shield mounted on the chassis in the space between the wheel assembly and the torch holder protects the carriage components from the heat of the torch. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Other objects and advantages of the invention will become apparent upon reading the following detailed description and upon reference to the drawings in which: 
     FIG. 1 is a top plan view of a preferred embodiment of the cutting/welding torch carriage; 
     FIG. 2 is a cross-sectional view taken along the line  2 — 2  of FIG. 1; 
     FIG. 3 is a front elevation view of the carriage of FIG. 1; 
     FIG. 4 is a cross-sectional view taken along the line  4 — 4  of FIG. 3; 
     FIG. 5 is a side elevation view of the carriage of FIG. 1; 
     FIG. 6 is a cross-sectional view taken along the line  6 — 6  of FIG. 5; 
     FIG. 7 is a top plan view of a preferred embodiment of a remote controller for the carriage of FIG. 1; and 
     FIG. 8 is an electrical schematic diagram illustrating the power and control circuits of the carriage of FIG.  1 . 
    
    
     While the invention will be described in connection with a preferred embodiment, it will be understood that it is not intended to limit the invention to that embodiment. On the contrary, it is intended to cover all alternatives, modifications and equivalents as may be included within the spirit and scope of the invention as defined by the appended claims. 
     DETAILED DESCRIPTION 
     Turning first to FIGS. 1 through 6, a carriage C carries a cutting or welding torch, which is used to cut, bevel or weld vertical or horizontal plate or pipe (not shown). 
     The carriage C consists of a frame or chassis  11  which is transported by a wheel assembly  13  with front and rear wheels  15  and  17 . The carriage C is held to the pipe or plate by the permanent magnets (not shown) located in the wheels  15  and  17  of the carriage C. An in line 90-volt D.C. reversible drive motor moves the carriage in a forward or reverse direction. Alternatively, the motor  19  can be non-reversing if a transmission  20  is employed. The current can be varied to the DC drive motor  19  to increase or decrease the velocity of the carriage C. 
     A torch holder assembly H is mounted on and carried by the chassis  11 . The torch holder assembly includes a torch arm block  23  which is mounted on the chassis  11  and supports a torch arm  25  which extends through the block  23  in a direction transverse to the direction of movement  27  of the carriage C. The torch arm  25  is longer than the carriage C is wide. A rack  29  extending long the length of the torch arm  25  engages with a pinion  31  on the shaft  33  of the torch arm motor  21 . The arm  25  is seated on rollers  35  so that the operation of the rack and pinion  29  and  31  drives the torch arm  25  to the left or right in response to the rotation of the torch arm motor shaft  33 . Thus, the direction of motion  37  of the torch arm  25  is perpendicular to the direction of motion  27  of the carriage C. The torch arm  25  extends through nylon bushings  41  and  43  which are spaced apart by an aluminum spacer  45 . Screws  47  secure the bushings and spacer  41 ,  43  and  45  in place. Tension cams  51  and  53  which support the rollers  35  on which the torch arm  25  moves, assure a firm sliding engagement between the chassis  11  and the torch arm  25  so as to minimize the possibility of deviation of these components. In order to assure that the slack between the chassis  11  and the torch arm  25  is securely taken up, tension adjustment screws  55  and  57  are used to lock the cams  51  and  53  in place after they have been rotated to properly position the rollers  35 . 
     The torch holder assembly H further includes a torch support  61  which is mounted on and extends transversely from one end of the torch arm  25 . A torch holder  63  is mounted on the torch support  61 . The torch holder can also be rotated in a clockwise or counterclockwise direction, preferably by use of a ratchet lever  69 , to create up to a maximum 40-degree forward or backward bevel on the work piece. As shown, the torch holder  63  is configured so as to hold the torch T in an upright or reference position in relation to the plane of the carriage wheels  15  and  17 . As shown, the torch holder  63  is engaged on the torch support  61  by use of a sleeve  65  rotatably mounted on a post  67  on the end of the torch holder  63 . Thus, the angular relationship of the torch T to the plane of the work piece on which the carriage C is transported can be varied by rotating the sleeve  65  on the post  67 . To this end, the ratchet lever  69  is mounted on the torch holder  63  to lock the torch holder  63  in selected angular relationship to the torch support  61 . In a preferred arrangement, by pulling and turning the ratchet lever  69 , the sleeve  65  is released for rotation to its desired angular position on the post  67 . Release of the ratchet lever  69  locks the holder  63  and the support  61  in this angular relationship. A 12-volt in line DC reversible gear motor  21  moves the torch holder  63  left or right  37 , perpendicular to the direction of movement  27  of the carriage C. The current can be varied to the torch arm or gear motor  21  to increase or decrease the velocity of the torch holder  63  on the perpendicular path  37 . 
     In addition to permitting variation in the angular relationship of the torch T to the work piece, the torch holder assembly H also permits variation of the distance between the torch T and the work piece. To this end, a rack  71  on the outer wall of the torch T engages with a pinion  73  connected to an adjustment knob  75  on the torch holder assembly H. Thus, by manual operation of the adjustment knob  75 , the distance of the torch T from the work piece can be upwardly or downwardly varied. As is best seen in FIG. 3, the torch T typically employs an oxygen valve  77 , an acetylene valve  79  and a mixing control valve  81  as part of the torch T. 
     A motor control box R shown in FIG. 7 remotely controls the functions of the carriage C. The motor control box R provides control of the speed and direction of the carriage C and speed and direction of the torch holder  63  in a direction  37  perpendicular to the carriage direction  27 . The box R has a case  83  containing the control circuitry hereinafter described in relation to FIG.  8 . On the face of the case  83 , a three-position toggle switch  85  is used to control the clockwise or counterclockwise rotation of the DC drive or carriage motor  19 . The center position of the three-position toggle switch  85  terminates DC current to the drive motor  19  and serves as an “off” position of the switch  85 . Moving the three-position toggle switch  85  of the motor control box R to left or right or forward or reverse position applies current to the in line 90-volt DC drive motor  19  to cause the carriage C to move in a forward or reverse direction. A rheostat  87  allows adjustment of the DC current to the DC drive motor  19  to control the DC drive motor speed and, therefore, the speed of the carriage C. Rotating the rheostat  87  clockwise or counterclockwise to increase or decrease the current to DC drive motor  19  causes the motor  19  and, therefore, the carriage C to go faster or slower. A three position momentary toggle switch  89  controls the direction of the DC in-line gearmotor or torch arm motor  21 . The center position of the three position momentary toggle switch  89  is the “off” position for the gearmotor switch  89 . Pushing the three position momentary toggle switch  89  to the right or left applies DC current to the 12-volt in line DC gear motor  21  and causes the 12-volt in line DC gearmotor  21  to rotate the pinion  31 . As the pinion  31  rotates, it moves the torch arm  25  left or right in the torch arm block  23 , thus moving the torch T perpendicular to the direction of carriage movement  27 . T Another rheostat  91  allows adjustment of the DC current to the gear motor  21  to control the gearmotor speed and, therefore, the speed of the torch arm  25 . Rotating the rheostat  91  clockwise or counterclockwise to increase or decrease the current of the DC gearmotor  21  causes the gearmotor  21  and, therefore, the torch arm  25  to go faster or slower. The motor control box R has a power cord  93  for connection to a 120 volt A.C. power source (not shown). As shown, the remote control box arm may also be provided with a master switch  94  permitting all of the circuits to be simultaneously energized or de-energized. There are five leads in the output cable  95  from the motor control box R. Two of the leads serve the 90 volt DC circuits and two serve the 12 volt DC circuits. The fifth lead connects the carriage C to earth ground. 
     The electrical circuits of the prototype device are illustrated in FIG.  8 . The input from a 120 V AC source is connected through the single pole, single throw master switch S 1  or  94  to a transformer T 1 . The carriage motor  19  is connected to the primary site of the transformer T 1  and controlled by the double pole, double throw, three position drive motor switch S 3  or  85 . The speed of the carriage motor is varied by the machine speed rheostat R 14  or  87 . The torch arm motor  21  is connected to the secondary side of the transformer T 1  and controlled by the three pole, double throw, three position torch arm switch S 2  or  89 . The speed of the torch arm motor  21  is varied by use of the torch arm speed rheostat R 1  or  91 . In the prototype circuit, the circuit components are connected as shown in FIG.  8  and identified in the following schedule of components: 
     
       
         
               
               
               
             
           
               
                   
                   
               
             
             
               
                   
                 C1 = 
                 1000uf63VDC 
               
               
                   
                 C2 = 
                 .0047uf 
               
               
                   
                 C3 = 
                 10uf 50VDC 
               
               
                   
                 C4 = 
                 .001uf 
               
               
                   
                 D1 = 
                 1AMP FULLWAVE BRIDGE 
               
               
                   
                 F1 = 
                 3AMP SLOBLOW 
               
               
                   
                 IC1 = 
                 MC33033P MOTOR CONTROLLER 
               
               
                   
                 1C2 = 
                 LM317T VARIABLE REGULATOR 
               
               
                   
                 Q1 = 
                 IRF510 
               
               
                   
                 Q2 = 
                 IRF510 
               
               
                   
                 Q3 = 
                 IRF510 
               
               
                   
                 R1 = 
                 10K ROCKER POT 
               
               
                   
                 R2 = 
                 8K 1/4W 
               
               
                   
                 R3 = 
                 5K 1/4W 
               
               
                   
                 R4 = 
                 10K 1/4W 
               
               
                   
                 R5 = 
                 4.7K 1/4W 
               
               
                   
                 R6 = 
                 2.7K 1/4W 
               
               
                   
                 R7 = 
                 240 OHM 
               
               
                   
                 R8 = 
                 1K 1/4W 
               
               
                   
                 R9 = 
                 .25 OHM 
               
               
                   
                 R10 = 
                 47 OHM 
               
               
                   
                 R11 = 
                 47 OHM 
               
               
                   
                 S1 = 
                 SPST SWITCH 
               
               
                   
                 S2 = 
                 3PDT 3POSITION 
               
               
                   
                 T1 = 
                 F-374P TRANSFORMER 
               
               
                   
                 C5 = 
                 .22uf 25OV 
               
               
                   
                 C6 = 
                 .1uf 250 V 
               
               
                   
                 C7 = 
                 .1uf 400 V 
               
               
                   
                 D2 = 
                 1N4005 DIODE 
               
               
                   
                 D3 = 
                 1N4005 DIODE 
               
               
                   
                 D4 = 
                 IN5406 DIODE 
               
               
                   
                 D5 = 
                 IN5406 DIODE 
               
               
                   
                 PUT = 
                 2N6027 TRANSISTER 
               
               
                   
                 R12 = 
                 47K 1/2W 
               
               
                   
                 R13 = 
                 3.3K 1/2W 
               
               
                   
                 R14 = 
                 50K 2W POT. 
               
               
                   
                 R15 = 
                 10K 1/2W POT. 
               
               
                   
                 R16 = 
                 22K 1/2W 
               
               
                   
                 R17 = 
                 47 OHM 1/2W 
               
               
                   
                 R18 = 
                 470 OHM 1/2W 
               
               
                   
                 R19 = 
                 4.7K 1/2W 
               
               
                   
                 R20 = 
                 4.7K 1/2W 
               
               
                   
                 S3 = 
                 DPDT 3 POSITION 
               
               
                   
                 SCR = 
                 2N6509 SCR 
               
               
                   
                   
               
             
          
         
       
     
     Many variations of these circuits will be obvious to those skilled in the art. The circuits shown are offered as a workable example. One suggested variation is the use of a rocker switch in place of the torch arm rheostat  91  so that the torch speed will vary according to the pressure applied to the rocker switch. 
     Preferably, the carriage C includes a mechanism for facilitating disengagement of the magnetic wheels  15  and  17  from the work piece. As best seen in FIGS. 2,  3  and  6 , the underside of the chassis  11  is provided with lifting blocks  101  in which a lifting block axle  103  is journaled. A lift lever  105  extends radially from the axle  103  and is long enough to engage against the work piece. A knob  107  on the end of the axle  103  is rotatable by the operator to cause the lever to engage against the work piece and pry the wheels  15  and  17  from the work piece. 
     The carriage is provided with a cover  111  having a handle  113  at one end to facilitate carrying and manipulation of the carriage C. To assure that the unit is not damaged by the heat of the torch T, a heat shield  115  mounted on spacers  117  is disposed between the carriage C and the torch T. Furthermore, as shown, to facilitate changes of the torch T and/or other components of the torch holder assembly H, the torch support  61  may be slidably engaged on the end of the torch arm  25  and a set screw  119  used to secure the torch support  61  in place on the arm  25 . 
     In a prototype of the carriage C, the carriage motor  19  was a 50-60 Hz, 110 v dc, 7500 rpm in-line motor. The torch arm or gear motor  21  was a 12/24 v dc in-line gear motor with a 218.4:1 ratio. 
     In operation, the carriage C is mounted on the pipe or plate close to the point where the pipe or plate is to be cut. The DC output lead  95  of the motor control box R is plugged into the device with the toggle switch  85  in the “off” position. The AC input lead  95  is plugged into a 120-volt power source. The three-position toggle switch  85  is moved to the left and then to the right to make sure the carriage C will move in the forward and reverse directions. The three-position toggle switch  85  is returned to the center or “off” position. The three position momentary toggle switch  89  is moved to the right and left to make sure the torch arm  25  will move left and right  37  perpendicular to the line of travel  27  of the carriage C. The torch T is lighted and adjusted to a distance from the work piece as required. The three position momentary toggle switch  89  is moved to the right and left until the torch T is located at the point where the pipe or plate is to be cut. The pipe or plate is preheated to the desired temperature. The three position toggle switch  85  is moved to the left or the right to start the carriage C moving in the desired direction  27 . The oxygen valve  77  of the torch T is rotated or flipped to the position necessary to cut, bevel or weld the work piece. As the carriage C moves on the work piece, the three position momentary toggle switch  89  is pushed to the right or left as necessary to move the torch T onto the desired path. When the operation is complete, the oxygen valve  77  is rotated or flipped to the “off” position and the three-position toggle switch  85  is moved to the center or “off” position to stop the movement of the carriage C. 
     Thus, it is apparent that there has been provided, in accordance with the invention, a cutting, beveling or welding torch carriage that fully satisfies the objects, aims and advantages set forth above. While the invention has been described in conjunction with a specific embodiment thereof, it is evident that many alternatives, modifications and variations will be apparent to those skilled in the art and in light of the foregoing description. Accordingly, it is intended to embrace all such alternatives, modifications and variations as fall within the spirit of the appended claims.