Plasma arc torches are commonly used for cutting, marking, gouging, and welding metal workpieces by directing a high energy plasma stream consisting of high temperature, high momentum ionized gas particles toward the workpiece. A typical plasma arc torch is commonly connected to a power supply through a torch lead, which generally provides a conduit for the delivery of both fluid (i.e., gas, liquid) and power and/or electrical control signals between the power supply and the plasma arc torch. The torch lead is often secured to the power supply using a quick disconnect such that the torch lead may be quickly and easily removed from the power supply. Additionally, the torch lead is also connected to a torch head of the plasma arc torch, wherein such a connection is typically fixed within a handle of the plasma arc torch and is not readily releasable.
Although torch leads are typically available in a variety of lengths according to requirements of a specific operation, a longer torch lead often causes more difficulty in operating the plasma arc torch. For example, a longer torch lead is heavier and more likely to become entangled with an object located between the power supply and the workpiece than a shorter lead. Additionally, longer torch leads are generally more expensive than shorter leads. Accordingly, the length of a torch lead is preferably kept to a minimum sufficient length.
Occasionally, a particular operation may require the torch to be operated at a considerable distance away from the power supply, a distance much greater than that for other operations. Although the operator may simply choose a torch lead that is long enough for all of the operations, the longer torch lead, as described earlier, will likely make the operation of the torch more difficult. Alternatively, the operator may instead purchase and maintain in inventory multiple torch lead and torch head assemblies, each of which is a different length. The operator may then switch between the torch lead and torch head assemblies as the need arises. However, the costs associated with purchasing and then maintaining multiple torch lead and torch head assemblies on-site are relatively high. Indeed, such costs are even higher if a separate power supply is required for each of the assemblies.
On other occasions, a particular operation may require the use of a plurality of plasma arc torches, each of which possesses one or more different characteristics such as operating amps, among others. For example, a first plasma arc torch may be required for a first operation such as gouging, and a second plasma arc torch may be required for another operation such as cutting. However, the torch leads connected to the first and second plasma arc torches may not both be adapted for connection to the same power supply. If so, the operator may choose to maintain two separate plasma arc torch systems on-site (i.e., the first plasma arc torch and first power supply, and the second plasma arc torch and second power supply) and switch between the two systems as the need arises. However, the costs associated with maintaining more than one complete plasma arc torch system on-site are relatively high. Alternatively, the operator may instead choose to replace an existing torch lead with a compatible torch lead. The operator may replace the torch lead in its entirety by removing a series of connections and fittings, such as electrical wires and compression fittings, and then reattaching a new torch lead through the same set of connections and fittings. With plasma arc torches of the known art, however, replacing the torch lead or the torch head is relatively time-consuming and rather cumbersome.
Additionally, in some applications it is necessary to splice signal wires into existing torch leads. An example is when a user has purchased a torch for use on a fully automated cutting system, wherein the torch and lead is provided with no trigger control on the torch since there is normally no desire to require a person in the loop to activate the trigger switch. Start and stop signals are provided to the plasma system via some external controller signaling the plasma system logic directly. If that user later tries to use this same torch and plasma cutting system on a less sophisticated motion control system (for instance one that only provides simple pattern cutting) the motion control system typically does not interact with the plasma cutting system. In such a situation, a person in the loop is required to provide a start/stop signal via a remote trigger switch that must be spliced into the torch lead. Once the remote trigger is installed it is then difficult to reinstall the torch on a fully automated cutting system, since there is now an open switch in the control loop.