Abstract:
A torch cable in which both the electrical connection and the pneumatic connection can be made concurrently in one motion by coupling the end of the torch cable to the exterior of the supply unit. The coupling further includes a quick disconnect feature. The torch cable coupling is simple and inexpensive, using standard off-the-shelf components. The end of the cable comprises various components that are overmolded to form an electrically insulative body, e.g., made of urethane rubber compound. This molded body incorporates strain relief, is water resistant, protects the electrical plug, and stabilizes the electrical contacts. Gas, power and control are combined in one assembly. The pneumatic quick disconnect coupling is used as a latching mechanism for the entire assembly. The torch cable can be disconnected from the supply unit by simply releasing the quick disconnect coupling and then pulling the end of the torch cable away from the supply unit. The pneumatic connector and the electrical plug form keying means by their orientation.

Description:
BACKGROUND OF THE INVENTION 
   This invention generally relates to welding or heating systems. In particular, the invention relates to plasma arc cutting units. 
   Plasma arc cutting is a process in which an electric arc is used to cut a metallic workpiece. Generally, plasma arc cutting uses an electric arc between an electrode and the metal to be cut. The arc creates a plasma that cuts the metallic workpiece. Plasma cutters are often used in applications such as building maintenance (structural or HVAC) where they are carried from job to job, and thus are preferably highly portable. 
   A typical prior art plasma arc cutter includes a. power supply, an air supply and a plasma torch. A plasma torch is used to create and maintain the arc and the plasma jet that perform the cutting. A plasma cutting power supply receives an input voltage (from a power line or generator) and provides an output voltage to a pair of output terminals, one of which is the electrode and the other of which is connected to the workpiece. There are numerous types of known plasma arc cutting power supplies, such as magnetic power supplies, inverter power supplies, phase control power supplies, and choppers or secondary switchers. A typical plasma cutting power supply includes one or more of each of the following: input power lines, transformers, converters/inverters, output power lines, and controllers, which cooperate to provide power to the electrode for maintaining the arc. 
   An air supply is used with most plasma cutters to help start the arc, control the torch, and cool the torch. For example, U.S. Pat. No. 4,791,268 to Sanders et al. describes a plasma torch controlled with air. A movable electrode is the cathode and a fixed nozzle is the anode. A pilot current is provided to the cathode and anode, which are forced into contact by a spring. After electrical current begins to flow from the electrode to the nozzle, gas or air supplied to the torch counteracts the spring force and moves the electrode away from the nozzle. This breaks the electrical contact between the electrode and the nozzle and creates the pilot arc. Also, as the electrode moves away from the nozzle, it opens a nozzle orifice (connected to the air supply), and a plasma jet is created. 
   The plasma jet causes the arc to transfer (at least in part) to the work piece, thus initiating cutting. Electronics in the power source sense when the arc has transferred and then supply a main cutting current of greater amperage after the transfer has occurred. Also, the torch tip is disconnected (electrically), interrupting the pilot current path. Thus, the current is used to cut the workpiece, and follows a path including the positive terminal, the workpiece and the electrode. 
   Plasma arc torches are widely used in the cutting or marking of metallic materials. A plasma torch generally includes an electrode and a nozzle having a central exit orifice mounted within a torch body, electrical connections, passages for cooling and arc control fluids, a swirl ring to control fluid flow patterns in the plasma chamber formed between the electrode and nozzle, and a power supply. The torch produces a plasma arc, which is a constricted ionized jet of a gas with high temperature and high momentum. Gases used in the torch can be non-reactive (e.g. argon or nitrogen), or reactive (e.g. oxygen or air). 
   One known configuration of a plasma arc torch includes one or more cables connecting the torch to the power supply to provide the torch with electrical current and gas. The connection of the cable(s) to the power supply must be rugged to handle the strain placed on the cable as it is manipulated in order to place the plasma arc torch in a suitable position to cut or mark a workpiece. 
   The cable(s) used to connect the torch to the power supply can be a single integral cable having a gas hose located in the middle of the cable and electrical conductors and fillers arranged symmetrically around the gas hose. A jacket material is extruded over the gas hose, electrical conductors and fillers. A strain relief mechanism can be attached to the jacket to handle loads applied to the cable. The jacket, gas hose, electrical conductors and fillers are anchored together over a barb-type fitting. A clamp, which acts as the strain relief mechanism, is applied to grab and hold the jacket to prevent relative axial motion (or twisting) of the cable components. The stress through the cable is absorbed by the clamp and transferred to the chassis of the power supply through a mechanical connection. 
   Cables with a clamp designed to prevent axial motion or twisting of cable components are disclosed in the prior art. The cable used in one plasma arc torch system is connected to the power supply by a threaded quick disconnect connector. A quick disconnect connector is advantageous in that it simplifies torch removal but is expensive to make. In another example of an integral cable with a clamp for preventing axial motion (or twisting) of cable components, stress is absorbed by the chassis of the power supply through a tool-tightened nut. A tool-tightened nut is advantageous in that it is inexpensive. 
   U.S. Pat. No. 6,4120,631, assigned to Hypertherm, Inc., discloses a plasma arc torch for piercing or cutting a workpiece. The plasma arc torch system includes a torch body, a power supply and a cable with two ends. One end of the cable is connected to the torch body, while the other end of the cable is attached to a strain relief system to couple the cable to the power supply. The strain relief system includes a positive axial restraint component for restraining axial movement of the cable relative to the power supply and a positive rotational restraint component for restraining rotational movement of the cable relative to the power supply. The positive axial and rotational restraint components are independent components arranged in a spaced relationship to each other. In one embodiment, the positive axial restraint component comprises a quick disconnect pneumatic connection attached to the cable and a quick disconnect pneumatic connection receptacle (which receives the pneumatic connection and itself is coupled to a supply of gas or air) positioned inside the power supply housing. The positive rotational restraint component comprises a shaped boot attached to the torch cable and a mating receptacle formed in the power supply housing. The shaped boot and the mating receptacle are designed to prevent rotation of the torch cable when the shaped boot is inserted in the mating receptacle. The electrical connection between the torch cable and the supply unit is independent of the quick disconnect pneumatic connection. Both the electrical connection and the quick disconnect pneumatic connection are located inside the housing. 
   There is a need for a torch cable in which both the electrical connection and the pneumatic connection can be made concurrently in one motion by coupling the end of the torch cable to the exterior of the supply unit. As used herein, the term “torch cable” includes both a cable having one end plugged directly into a supply unit and having a torch connected at the other end as well as a cable having one end connected to the supply unit via one or more extension cables and having a torch connected to its other end. In the latter case, the cable carrying the torch and the one or more extension cables, when connected in series, form a “torch cable”. 
   BRIEF DESCRIPTION OF THE INVENTION 
   The invention is directed to a torch cable in which both the electrical connection and the pneumatic connection can be made concurrently in one motion by coupling the end of the torch cable to the exterior of the supply unit. The coupling further includes a quick disconnect feature. The torch cable coupling is simple and inexpensive, using standard off-the-shelf components. The end of the cable comprises various components that are overmolded to form an electrically insulative body, e.g., made of urethane rubber compound. This molded body incorporates strain relief, is water resistant, protects the electrical plug, and stabilizes the electrical contacts. The invention allows gas, power and control to be combined in one assembly. In one embodiment of the invention, the pneumatic quick disconnect coupling is used as a latching mechanism for the entire assembly. The torch cable can be disconnected from the supply unit by simply releasing the quick disconnect coupling and then pulling the end of the torch cable away from the supply unit. The pneumatic connector and the electrical plug form keying means by their orientation. The pneumatic connector on the supply unit can be either self-closing or straight through when the torch cable is uncoupled. 
   One aspect of the invention is a torch assembly comprising a torch cable and a torch coupled to one end of the torch cable, the torch comprising an electrode, and the torch cable comprising: a fitting having a passageway; a hose having a passageway for guiding gas from the passageway of the fitting to the torch; a plurality of insulated wires adjacent and external to the hose, at least some of the wires being electrically coupled to the electrode of the torch; a plurality of electrical connectors respectively electrically coupled to the wires; an electrically insulative support structure that supports the plurality of electrical connectors in a spaced and individually electrically isolated relationship; a sheath surrounding the hose along at least a portion of the hose&#39;s length, the insulated wires passing between the hose and the sheath; and an electrically insulative body proximal to the other end of the torch cable. The body holds the support structure and the fitting in a fixed spatial relationship. 
   Another aspect of the invention is a system for coupling one end of a torch cable to a supply unit that supplies both power and pressurized gas, the torch cable in turn carrying power and pressurized gas from the supply unit to a torch coupled to the other end of the torch cable. One end of the torch cable comprises first pneumatic connection means and first electrical connection means, while the supply unit comprises second pneumatic connection means designed to couple with the first pneumatic connection means, second electrical connection means designed to couple with the first electrical connection means, and a panel to which the second pneumatic connection means and the second electrical connection means are mounted. The one end of the torch cable further comprises a molded body of electrically insulative material in which respective portions of the first pneumatic connection means and the first electrical connection means are embedded and held in a fixed spatial relationship with mutually parallel axes. This parallelism allows the first pneumatic connection means and the first electrical connection means to be respectively coupled to the second pneumatic connection means and the second electrical connection means during the same movement of the molded body toward the panel. 
   A further aspect of the invention is a system for coupling one end of a torch cable to a supply unit that supplies both power and pressurized gas, the torch cable in turn carrying power and pressurized gas from the supply unit to a torch coupled to the other end of the torch cable. One end of the torch cable comprises a body of electrically insulative material, a fitting having a passageway and an outer periphery surrounded by a first portion of the body, a first coupling element having one end coupled to the fitting and having a passageway in fluid communication with the passageway of the fitting, and an electrical plug having an outer periphery surrounded by a second portion of the body. The supply unit comprises a panel, a second coupling element mounted to the panel that couples with the first coupling element, and an electrical socket mounted to the panel that receives the electrical plug. The body supports the fitting and the electrical plug in a fixed spatial relationship that allows the first and second coupled elements to be coupled to each other and the electrical plug to be plugged into the electrical socket during the same movement of the body toward the panel. 
   Yet another aspect of the invention is a system for coupling one end of a torch cable to a supply unit that supplies both power and pressurized gas, the torch cable in turn carrying power and pressurized gas from the supply unit to a torch coupled to the other end of the torch cable. One end of the torch cable comprises a body of electrically insulative material, a fitting having a passageway and an outer periphery surrounded by a first portion of the body, a first coupling element having one end coupled to the fitting and having a passageway in fluid communication with the passageway of the fitting, and an electrical socket having an outer periphery surrounded by a second portion of the body. The supply unit comprises a panel, a second coupling element mounted to the panel that couples with the first coupling element, and an electrical plug mounted to the panel that is received by the electrical socket. The body supports the fitting and the electrical plug in a fixed spatial relationship that allows the first and second coupled elements to be coupled to each other and the electrical plug to be plugged into the electrical socket during the same movement of the body toward the panel. 
   A further aspect of the invention is a torch assembly comprising a torch cable and a torch coupled to one end of the torch cable, the torch comprising an electrode, and the torch cable comprising: a fitting having a passageway; a hose having a passageway for guiding gas from the passageway of the fitting to the torch; a plurality of insulated wires adjacent and external to the hose, at least one of the wires being electrically coupled to the electrode of the torch; a plurality of electrical connectors respectively electrically coupled to the wires; an electrically insulative frame having a plurality of cavities in which the electrical connectors are respectively inserted in mutually spaced and electrically isolated relationship; a body in which the fitting, the frame and portions of the insulated wires are embedded and restrained from relative movement; and a sheath surrounding the hose along at least a portion of the hose&#39;s length, the insulated wires passing between the hose and the sheath. 
   Another aspect of the invention is a method of quickly connecting the power and gas lines of a torch to a supply unit, comprising the following steps: manufacturing a torch cable in which the power and gas lines are inside a sheath, and a first power coupling element connected to the power line and a first gas coupling element connected to the gas line are spaced apart from each other by a predetermined distance and have parallel axes; manufacturing a panel of the supply unit so that a second power coupling element in electrical communication with a power supply and a second gas coupling element in fluid communication with a gas supply are spaced apart from each other by a predetermined distance and have parallel axes; and engaging the first power coupling element with the second power coupling element and the first gas coupling element with the second coupling element by a single continuous movement of the end of the torch cable toward the panel. 
   Yet another aspect of the invention is a system comprising: a torch cable comprising power and gas lines, a sheath surrounding respective portions of the power and gas lines, a first power coupling element connected to the power line, a first gas coupling element connected to the gas line, and means for supporting the first power coupling element and the first gas coupling element in a fixed spatial relationship spaced apart from each other by a predetermined distance; and a supply unit comprising a panel, a second power coupling element in electrical communication with a power supply and mounted to the panel, and a second gas coupling element in fluid communication with a gas supply, the second power coupling element and the second gas coupling element being in a fixed spatial relationship spaced apart from each other by the predetermined distance. The first and second power coupling elements and the first and second gas coupling elements are arranged so that the first power coupling element can be engaged with the second power coupling element and the first gas coupling element can be engaged with the second coupling element by a single continuous movement of the end of the torch cable toward the panel. 
   Other aspects of the invention are disclosed and claimed below. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a block diagram representing a prior art plasma arc cutting system having an integral compressor. 
       FIG. 2  is a drawing showing a cross-sectional view of a conventional plasma arc torch. 
       FIG. 3  is a drawing showing an isometric view of a prior art plasma arc torch mounted to a portion of the power supply housing or cover, indicated by hatching. 
       FIG. 4  is a drawing showing various components of a quick disconnect plasma torch system in accordance with one embodiment of the present invention. The cable of the plasma torch is shown in proximity to, but not yet coupled to, an electrical receptacle and a quick disconnect pneumatic connector located on a panel of the supply unit. 
       FIG. 5  is a drawing showing the components of  FIG. 4  in a coupled state. 
       FIG. 6  is a drawing showing the components of  FIG. 4  in a coupled state, but with the molded body on the end of the torch cable removed. 
       FIG. 7  is a drawing showing a sectional view of the torch cable partly shown in  FIG. 6 , the section being taken through the air hose and sheath. 
       FIG. 8  is a drawing showing the ends of the air hose and sheath with a plurality of insulated wires exiting the annular space between the hose and sheath. In accordance with one method of manufacture, a fitting will be inserted in the end of the hose, the electrical connectors crimped onto the ends of the wires will be inserted in a plug, and the plug and fitting will be overmolded to form a body that holds the plug and fitting in place. 
       FIGS. 9 and 10  are drawings showing side and end views respectively of the fitting that is inserted into the air hose and is later coupled to a pneumatic connector. The end view of  FIG. 10  is taken from a vantage point to the right of the fitting as seen in  FIG. 9 . 
       FIG. 11  is a drawing showing a side view of a pneumatic connector that is coupled to the torch cable fitting and forms part of the quick disconnect coupling. A pair of rolling elements (e.g., balls or rods) incorporated in the quick disconnect pneumatic connector on the supply unit are indicated by dashed lines. 
       FIG. 12  is a drawing showing a side view of a pin assembly of the type used in the disclosed embodiments of the invention to provide electrical connections for power and control. 
       FIG. 13  is a drawing showing a sectional view of a crimpable portion of the pin assembly of  FIG. 12 , the section being taken along line  13 — 13  indicated in  FIG. 12 . 
       FIG. 14  is a drawing showing a side view of a socket assembly of the type used in the disclosed embodiments of the invention to provide electrical connections for power and control. This socket assembly is designed to receive and couple with the pin assembly depicted in  FIG. 12 . 
       FIG. 15  is a drawing showing an end view of the socket assembly of  FIG. 14 . The end view of  FIG. 15  is taken from a vantage point to the left of the socket assembly as seen in  14 . 
       FIG. 16  is a drawing showing a sectional view of a crimpable portion of the socket assembly of  FIG. 14 , the section being taken along line  16 — 16  indicated in  FIG. 14 . 
       FIG. 17  is a drawing showing a front view of a plug incorporated in the torch cable end in accordance with one embodiment of the invention. 
       FIG. 18  is a drawing showing a front view of a flanged receptacle housing that is mounted to a panel on the supply unit for the same embodiment of the invention. 
   

   Reference will now be made to the drawings in which similar elements in different drawings bear the same reference numerals. 
   DETAILED DESCRIPTION OF THE INVENTION 
   The present invention is concerned with the coupling of a plasma arc cutting torch or an arc welding torch to a power supply unit and structures for accomplishing such coupling. The invention is not limited in any sense to a particular torch or to a particular power supply unit. For the sake of illustration, a known plasma arc cutting system will be described with reference to  FIG. 1  and a known plasma arc torch will be described with reference to  FIG. 2 . However, it should be appreciated that the quick disconnect feature of the present invention can be used in other plasma arc cutting systems with other plasma arc torches as well as in arc welding systems. 
     FIG. 1  (taken from U.S. Pat. No. 6,194,6130) shows a known plasma cutter  100  having an air compressor  114  disposed in a housing  120 . Plasma cutter  100  includes a power source  102  that provides power to a cutting power supply  104  and air power supply  112 . Power source  102  may include a transformer core and a primary winding shared by the compressor and cutter, with separate secondary windings. 
   Power source  102  may include, in alternative embodiments, a secondary winding that provides power to the compressor and cutter power circuit (using either the same or different secondary taps), or a shared transformer and rectifier, with power from the rectifier feeding (directly or indirectly) power to the cutting power circuit  104  and the compressor  114 . Power source  102  may include, in another alternative embodiment, a separate transformer (core and windings), but a common connector to utility or engine power (such as a standard 110 Vac plug). The cutting power supply  104  provides cutting power on a pair of lines  107  and  108  to a plasma torch  106 . Cutting power supply  104  is controlled by a controller  110 . Feedback may be provided from cutting power supply  104  and/or output lines  107  and  108 , and/or torch  106  to the controller  110 . The feedback may be used to regulate the cuffing power supply  104 , and can include voltage, current, power, and functions thereof, a trigger signal (e.g., from torch  106 ), and user-selectable or fixed setpoints. The term “trigger signal” includes any signal from the user indicating an intention to cut or the completion of a cut, and can be from the torch or the control panel (not shown). 
   Air power supply  112  provides power to a compressor  114 . Air power supply  112  is also controlled by controller  110 , and common control signals and feedback signals are used to control air power supply  112  and cutting power supply  104 : Compressor  114  provides air via an air hose  116  to the torch  106 . Feedback may be provided from the output of the air power supply  112 , or from within the air power supply  112 , to controller  110  to control or regulate air power supply  112 . Additionally, feedback signals from torch  106  (such as a trigger signal) and/or cutting power supply  104  may also be used to regulate air power supply  112 . 
   Typically, the power supply provides continuously variable current output within a range, e.g., from about 20 to 40 amperes. This range can be lower or higher depending on the torch system, the thickness the workpiece and the desired cutting speeds. The variable power supply allows for wide variations in cutting speeds for a given thickness of metal. 
   A typical plasma arc torch comprises a torch body connected to the power supply by a cable. The power supply is enclosed by a housing. The cable is connected to the power supply by a strain relief system. The cable provides the torch body with a plasma gas from a gas source and electrical power from the power supply to ignite and sustain a plasma stream. In some embodiments, air is used as the plasma gas, but other gases can be used to improve cut quality on metals such as stainless steel and aluminum. A workpiece lead (not shown) provides a return path for the current generated by the power supply and is typically connected to a workpiece (not shown) by a clamp (not shown). 
     FIG. 3  (taken from U.S. Pat. No. 6,4120,631) illustrates in simplified schematic form a plasma arc torch representative of any of a variety of models of torches. The torch has a body  118  that is generally cylindrical with an exit orifice  120  at a lower end  122 . A plasma arc  124 , i.e., an ionized gas jet, passes through the exit orifice  120 . The torch is used to pierce and cut metal, such as mild steel or other electrically conducting materials, in a transferred arc mode. In cutting mild steel, the torch operates with a reactive gas, such as oxygen or air, or a non-reactive gas, such as nitrogen or argon, as the plasma gas to form the transferred plasma arc. 
   The torch body  118  supports an electrode  92  having an insert  136  in its lower end and a nozzle  126  spaced from the electrode  92 . The nozzle  126  has a central orifice that defines the exit orifice  120 . A swirl ring  128  is mounted to the torch body  118 . In one embodiment, the swirl ring  128  has a set of radially offset (or canted) gas distribution holes  130  that impart a tangential velocity component to the plasma gas flow causing it to swirl. This swirl creates a vortex that constricts the arc and stabilizes the position of the arc on the insert  136 . 
   In operation, the plasma gas flows through a gas inlet tube  132  and the gas distribution holes  130 . The gas flows into the plasma chamber  134  and out of the torch through the exit orifice  120 . A pilot arc, which ionizes the gas passing through the exit orifice, is first generated between the electrode  136  and the nozzle  126 . The arc then transfers from the nozzle to a workpiece  138 . The particular construction details of the torch body, including the arrangement of components for directing gas flow and providing electrical connections, can take a wide variety of forms. 
   A commercially available plasma arc torch assembly  10  is shown in  FIG. 3 . The torch assembly  10  comprises a torch cable that penetrates an opening in a wall or panel  34  of the power supply housing and is fastened to that wall by means of a pair of nuts  2  and  4  coupled to a threaded section  20  on opposing sides of panel  34 . A strain relief system  18  is integrally formed with the threaded section  20 , the integrally formed part having a bore through which the torch cable passes. The outer sheath  16  of the cable is joined to one or both of sections  18  and  20 . The outer sheath  16  is made of electrically insulative, flexible and water impermeable material. The outer sheath  16  surrounds a flexible air hose  22 . The end of the air hose  22  receives a pneumatic connector  24  that couples to another connector (not shown) for supplying pressurized gas. Two sets of insulated wires pass through the annular space between the sheath  16  and hose  22 . One set  26  of insulated wires terminate at electrical connectors in a plug  28  that will be plugged into a first receptacle (not shown) that communicates with a power circuit (such as power circuit  102  in  FIG. 1 ) for providing power to the torch, while another set  30  of insulated wires terminate at electrical connectors in a plug  32  that will be plugged into a second receptacle (not shown) that communicates with a controller (such as controller  110  in  FIG. 1 ). 
   The other end of the torch cable is connected to a torch  12  comprising an electrode (not shown in  FIG. 3 , but see  FIG. 2 ), a nozzle  6 , and a trigger  8 . Another strain relief system  14  relieves strain in the area where the torch  12  meets the cable. The electrode inside the torch  12  receives power via insulated wires  26 , while operation of the trigger  8  produces control signals that reach the controller via insulated wires  30 . 
   When repairing or replacing the torch or the cable that couples the torch to the power supply, it is important that the cable can be quickly disconnected from the power supply. In addition, operators often wish to disconnect the torch from the power supply for convenience during storage or transport of the system. The torch cable shown in  FIG. 3  requires three separate operations for disconnection, to wit, unplugging of power plug  28  from its receptacle; unplugging of control plug  32  from its receptacle; and unscrewing of nut  4  that fastens the torch cable assembly  10  to the wall or panel  34 . 
   The present invention is directed to a torch cable assembly that can be disconnected in one simple operation. This is achieved by building the end of the torch cable so that the electrical and pneumatic connectors have a fixed spatial relationship and can be coupled to the supply unit simultaneously with one motion, as seen for example, in  FIGS. 4 and 5 . In this embodiment, a quick disconnect pneumatic connector or coupling element  42  is mounted to a wall or panel  40  of the supply unit. The end of pneumatic connector  42  located inside the supply unit is connected (by means not shown in  FIG. 4 ) to a source of pressurized gas. The quick disconnect pneumatic connector  42  receives a mating pneumatic connector  54  disposed on the end of the torch cable. Connectors  42  and  54  may comprise respective parts of a ball locking-type coupling, in which case connector  42  comprises a sleeve  44  that is axially slidable between locking and releasing positions. Typically, the release movement is toward the panel  40 , but the sleeve could also be a rotatable type to unlock the coupling. A lever or button could also be used to unlock the coupling. The coupling is preferably self-locking when the connector  54  is fully inserted into connector  42 . The connector  42  further comprises a plurality of rolling elements  55  (two of which are indicated by dashed circles in  FIG. 11 ). For example, the rolling elements may be balls or circular cylindrical rods. The rolling elements  55  seat in a circumferential raceway  56  formed on the outer periphery of the pneumatic connector  54 . The pneumatic connector  54  is a hardened steel part. The interference of the rolling elements  55  latches the connector  54  inside the connector  42 . At the same time, this latches the electrical plug to the electrical socket, as described below. 
   Referring again to  FIGS. 4 and 5 , an electrical socket is mounted to the panel  40 , while an electrical plug is incorporated in the end of the torch cable. The electrical socket comprises an electrically insulative frame  46  having an array of mutually parallel cavities  38  (see  FIG. 18 ), each cavity receiving a respective socket assembly  94  of the type shown in  FIGS. 14–16 . The frame  46  holds the socket assemblies in a mutually spaced apart and electrically isolated relationship. Each socket assembly  94  comprises a brass electrical connector and a stainless steel spring  99  that holds the brass connector inside a respective cavity of frame  46 . One end of the brass electrical connector comprises a ferrule  96  that forms a socket (seen in  FIG. 15 ), while the other end has a two pairs of crimpable wings  97  and  98  (wings  97  are seen in FIG.  16 ) which are crimped onto the uninsulated end of a respective one of a plurality of insulated wires  48 . Some of wires  48  are coupled to the power circuit, while others are coupled to the controller. The frame  46  is fastened to the panel  40  (see  FIG. 4 ) by means of a mounting flange  36  (see  FIG. 18 ) that extends generally perpendicular to the axes of the cavities  38 . 
   The electrical plug comprises an electrically insulative frame  52  having an array of mutually parallel cavities  38  (see  FIG. 17 ), each cavity receiving a respective pin assembly  70  of the type shown in  FIGS. 12 and 13 . The plug frame  52  holds the pin assemblies in a mutually spaced apart and electrically isolated relationship. The pin assembly  70  comprises a brass electrical connector and a stainless steel spring  92  that holds the brass connector inside a respective cavity of frame  52 . One end of the brass electrical connector comprises a pin  86  that is inserted in a socket of a mating socket assembly of the panel-mounted electrical socket, and two pairs of crimpable wings  88  and  90  (wings  88  are seen in  FIG. 13 ) which are crimped onto the uninsulated end of a respective one of a plurality of insulated wires  62 , as seen in  FIG. 8 . Some of wires  62  carry power to the torch, while other wires  62  transmit control signals, e.g., signals representing actuation of the torch trigger by the system operator. 
     FIG. 4  shows the end of the torch cable in proximity to but not coupled to the panel of the supply unit.  FIG. 5  shows the fully coupled state wherein both the pneumatic and electrical connections have been made by engaging the end of the torch cable with the receptacles  42  and  46  on the panel. The pneumatic connector  54  is fully inserted in the quick disconnect pneumatic connector  42 , while the pins of the electrical plug are fully inserted into the respective sockets inside the cavities of the socket housing or frame  46 . This can be accomplished with one motion of the torch cable end toward the panel. The cavities of plug frame  52  align with the cavities of socket frame  46  so that the pin assemblies of the former will be inserted into the socket assemblies of the latter when the plug is inserted into the socket with the correct orientation. The pneumatic connector  54  and the electrical plug form keying means by their orientation. 
   As best seen in  FIG. 4 , the end of the torch cable comprises a molded body  50  of electrically insulative material. The molded body holds the pneumatic and electrical connectors of the torch cable end in a fixed spatial relationship. The electrical plug is embedded in the molded body, whereas the pneumatic connector  54  is not embedded in the molded body  50 .  FIG. 6  shows the end of the torch cable with the molded body removed for the purpose of revealing the structure that is embedded in the molded body. The molded body will reach and be joined to the end of a cable sheath  60  made of electrically insulating material. The sheath  60  surrounds a flexible hose  72 , which protrudes out of the sheath by a certain distance, as best seen in  FIG. 8 .  FIG. 7  shows the hose  72  arranged generally concentrically inside the sheath  60 . The hose  72  carries pressurized gas from the quick disconnect gas coupling to the torch. The annular space between the hose and sheath is occupied by the insulated wires  62 , which run the length of the torch cable. In one exemplary construction, there are seven power wires and three control wires, giving a total of ten, as seen in  FIG. 7 .  FIG. 8  shows only six of the ten wires for the sake of economy and to avoid clutter in the drawing. However, the number of wires passing through the cable may be different than ten. Although not shown in  FIG. 7 , it is known to fill empty spaces between adjacent wires inside the sheath with a filler made, e.g., of rope to provide support. 
   Referring to  FIG. 6 , the pneumatic connector  54  is in fluid communication with the hose  72  via a metal (e.g., brass) fitting  74 . The structure of the pneumatic connector  54  is shown in detail in  FIG. 11 , while the structure of the fitting  74  is shown in detail in  FIGS. 9 and 10 . The fitting  74  has a small-diameter end  80  and a large-diameter cup-shaped portion that starts from the opposite end. The small-diameter end is inserted inside the hose and is provided with wedge-shaped ridges on the outer periphery that facilitate insertion and resist removal. The hose is held on to the narrow end of the fitting  74  by a clamp  68  (more than one clamp can be used). The large-diameter end has a threaded bore into which a threaded end  57  of the pneumatic connector  54  (see  FIG. 11 ) is screwed, thereby coupling the pneumatic connector  54  to the fitting  74 . The connector  58  has a hexagonal flange  58  to facilitate tightening of the connector into the fitting using a tool. As best seen in  FIG. 10 , the fitting has a passageway  82  in the small-diameter section, which will be in fluid communication with the hose and the passageway of the pneumatic connector  54  when the latter is screwed into the large-diameter threaded bore  84  of the fitting. 
   Only the hexagonal flange of the pneumatic connector  54  is visible in  FIG. 6  because the threaded end  57  is inserted inside the fitting  74 , while the section on the other side of the hexagonal flange that carries the raceway  56  is inserted inside the quick disconnect pneumatic connector  42 , where it is engaged by the plurality of rolling elements  55  (only two of which are depicted in  FIG. 11 ). The interference of the rolling elements  55  with the raceway  56  latches both the pneumatic and electrical connections together. Both can be disconnected by the simple expedient of sliding the sleeve  44  (see  FIG. 4 ) toward the panel  40  and then pulling the pneumatic and electrical coupling elements incorporated on the end of the torch out of the pneumatic and electrical coupling elements mounted to the panel. 
   Referring again to  FIG. 6 , the fitting  74 , the electrical plug and insulated wires connected thereto, the end of the hose  72 , the clamp  68  and a nylon cable tie  66  (the cable tie is optional) will be placed in a mold that holds the plug and fitting in a predetermined spatial relationship to each other and to the hose. These parts of the assembly are then overmolded to form the molded body  50  seen in  FIGS. 4 and 5 . One suitable material for forming the molded body is a urethane rubber compound, but other materials having similar properties can be used. After the material of the molded body has cured, the pneumatic connector  54  (see  FIG. 11 ) is screwed into the large-diameter end of the fitting  74 , which is exposed and not enclosed by the molded body. Similarly, the front face of the electrical plug, with a plurality of pins protruding therefrom is exposed and not covered by the molded body, so that the plug can be coupled to the socket on the panel of the supply unit. 
   As seen in  FIG. 9 , the fitting  74  may be provided with one or more recesses that are filled with the material of the molded body so that the fitting is restrained from displacing or rotating relative to the molded body. The recesses may take the form of a plurality of axial grooves circumferentially distributed at angular intervals on the periphery of the fitting, which prevent rotation of the fitting relative to the molded body when filled with material during overmolding. Additional recesses  78  may be provided to prevent axial displacement of the fitting relative to the molded body when filled with material during overmolding. 
   While the invention has been described with reference to preferred embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for members thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation to the teachings of the invention without departing from the essential scope thereof. For example, instead of placing the electrical plug on the end of the torch lead and the electrical socket on the power supply unit, the electrical socket could be placed on the end of the torch lead while the electrical plug is mounted to the power supply unit. In addition, the fitting and quick disconnect connector could be formed as a monolithic structure. Therefore it is intended that the invention not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this invention, but that the invention will include all embodiments falling within the scope of the appended claims. 
   As used in the claims, the term “torch” is defined broadly to encompass plasma arc cutting torches as well as arc welding torches or guns.