Centralized joint for plasma arc cutting torches

Abstract: A joint for plasma arc cutting torches comprising a fixed female element, to be applied to the generator, and a movable male element, being connected to the torch, which can be fitted into said fixed element and is provided with a ring (5) which can be screwed on said fixed element, and a sleeve (11) engaging said ring, means (15, 16), which can be disengaged by a tool, being provided for engaging said sleeve in order to prevent its rotation.

Description: The present invention provides a joint for plasma arc cutting torches comprising a fixed female element, to be applied to the generator, and a movable male element, being connected to the torch, which can be fitted into said fixed element and is provided with a ring which can be screwed on said fixed element, wherein said joint comprises a sleeve engaging said ring and some means, which can be disengaged by a tool, engaging said sleeve in order to prevent its rotation. In particular, the female element comprises a ring to be fixed to the generator which the torch is connected to, and a sleeve, which can freely rotate relative to said fixed element and engage, by means of facets, teeth or the like, the torch ring which is thus made integral, by rotating, with said sleeve. The joint further comprises a pin, being pressed by a spring, for engaging said sleeve in order to prevent its rotation, it being possible for the user to disengage said pin by means of a tool. The invention falls within the field of cutting and welding torches, in particular TIG and plasma torches. In order to connect the torches to their current generator, standardized joints are used comprising a female threaded element which is fixed to the frame of the generator and into which a male element is fitted being connected to the torch, said male element being then blocked in its position by screwing a threaded ring on the fixed element. As mentioned above, at present these joints are standardized and they are the same both for TIG-welding torches and for plasma arc cutting torches. However, this situation is dangerous, since TIG-welding torches operate at relatively low voltage, not higher than 113 peak volts, whereas plasma torches can operate at much higher voltages, reaching even about 400 volts. It is clear then that the use of a single standardized joint for the two kinds of torches may cause dangerous situations, since the wrong kind of torch may be applied to a joint out of inexperience or by mistake. US-A-3 194 588 discloses a joint suitable for plasma are cutting torches, comprising a fixed female element, to be applied to the generator, and a movable male element being connected to the torch, which can be fitted into said fixed element and is provided with a ring which can be screwed on said fixed element. On said fixed element the joint is provided with a sleeve engaging said ring, means being provided, which may be disengaged by a tool (screwdriver) for engaging said sleeve in order to prevent its rotation. female threaded element which is fixed to the frame of the generator and into which a male element is fitted being connected to the torch, said male element being then blocked in its position by screwing a threaded ring on the fixed element. Whereas fitting a plasma torch on a TIG joint does not involve particular drawbacks but the non-operation of the equipment, fitting the TIG torch, having low voltage insulation, on a joint for plasma torches through which a much higher voltage is supplied, causes a considerably dangerous situation for the user. For this reason it is convenient to provide different joints for these two kinds of torches and, in particular, such a joint for plasma torches to exclude the possibility of connecting TIG torches. Preferably, however, this joint shall be compatible with the ones currently used, in order to make it possible to fit it also on already existing equipment. Furthermore, this joint may be manufactured by slightly modifying existing dies, without, therefore, having to make some new ones, with a clear advantage for the manufacturing firm. The above stated problem is solved by the joint of the invention, which is characterized by its particular configuration allowing it to be fitted on existing equipment. Moreover, the joint of the invention shares a lot of components with the present TIG-plasma joints, thus it being possible to manufacture said components by using the already existing dies. The present invention will now be described in detail, by way of non limiting example, with reference to the accompanying drawings in which: Figure 1 is a perspective view of a joint for plasma arc cutting torches according to the invention; Figure 2 is a perspective view of the fixed or female element of a joint according to the invention; and Figure 3 is a sectional view of the fixed element of a joint as shown in Figure 2. With reference to Figure 1, a joint for plasma arc cutting torches according to the invention comprises a male element, being connected to the torch by means of a cable 2, and a female fixed element 3, which is connected to the generator. Each element 1 and 3 is provided with a plurality of electrical connectors 4 being connected when male element 1 is fitted into female element 3. Male element 1 is provided with an inwardly threaded ring 5, which is screwed on a corresponding thread 6 of the fixed element, in order to firmly join elements 1 and 3. The front of ring 5 has two flat portions 7. With reference to Figures 2 and 3, the fixed element 3 of the joint comprises a body 8, which is fitted on the wall 9 of the generator, a ring 10 and a sleeve 11, being coaxial with body 8. The fixed ring 10 is provided with a tooth 12 which fits into a corresponding seat in the wall 9 of the generator in order to prevent said ring 10 from rotating. A nut 13, being screwed on a thread of body 8 and tightening against wall 9 and ring 10, blocks the joint in its position. Sleeve 11, which is fitted on ring 10, may rotate around the axis of the joint and is inwardly provided with a pair of flat walls 14 corresponding to flat portions 7 on ring 5. When joint element 1 is fitted on female element 3, ring 5 engages sleeve 11 and, as it gets screwed on thread 6, it leads said sleeve 11 into rotation. Outer ring 10 is provided with a seat through which a pin 15 slides, said pin 15 being pressed by a helical spring 16 to engage teeth 17 on sleeve 11. Pin 15 projects circumferentially relative to sleeve 11 (see Figure 3) and the projecting portion is accessible through a hole 18 at the front of ring 10, said hole permitting to insert a tool, such as a point or the like, schematically shown at 19, by which it is possible to operate on pin 15 by pushing it inwards, thus disengaging teeth 17. The use is as follows. The joint female element 3 is fitted on the generator, by inserting body 8 into the hole of wall 9, external ring 10 leaning against the wall and tooth 12 fitting inside the provided seat. Nut 13 is screwed on body 8 and is tightened, thus blocking the whole in position. In order to connect the torch the user fits the joint male element into fixed element 3, ring 5 penetrating into sleeve 11, flat portions 7 being in contact with sleeve walls 14. At this point ring 5 and sleeve 11 can slide relative to each other, but they are bound to rotate by the engagement between walls 7 and 14. Spring 16 presses pin 15, thus fitting it between teeth 17 on the edge of sleeve 11, this way preventing said sleeve and said ring 5 from rotating. However, in order to fix the two joint elements 1 and 3 and connect them firmly, ring 5 needs to be screwed on thread 6 and, to this purpose, the user must fit tool 19 into hole 18, thus pushing pin 15 back in order to disengage teeth 17 of sleeve 11. Said sleeve 11 can then rotate freely and, as a consequence, the user can screw ring 5 on thread 6. As soon as it is released, pin 5 gets back to its former position by engaging teeth 17 again and stopping the rotations of sleeve 11, thus preventing joint element 1 from being removed. In order to remove said element 1 it is necessary to use tool 19 to push pin 15 back and release the sleeve, permitting said sleeve and ring 5 to rotate in the opposite sense, in order to unscrew the ring and disengage it from thread 6. As mentioned above, this solution offers several advantages. As a matter of fact, a joint is provided which, though mostly comprising the same components which are currently used for manufacturing TIG joints, and therefore being cheap to produce, offers a high degree of safety, since sleeve 11 with flat walls 14 prevents TIG torch joints from being fitted, said joints lacking flat portions 7. Furthermore, the need to use a tool for fitting up and removing the movable joint element prevents it from being used by unskilled people. Different embodiments of the joint may then be included within the scope of the invention as set forth in the following claims. In particular, the engagement between ring 5 and sleeve 11 may also be performed in some different ways, for example by providing the two elements with projections and cavities respectively, so as to ensure an engagement which permits sliding but prevents the reciprocal rotation of the parts. The dimensions, as well as the materials used, may change according to the requirements of use.

Claims: A joint for plasma arc cutting torches, comprising a fixed female element (3), to be applied to the generator, and a movable male element (1), being connected to the torch, which can be fitted into said fixed element and is provided with a ring (5) which can be screwed on said fixed element, on said fixed element the joint being provided with a sleeve (11) engaging said ring (5), characterized in that a pin (15) is provided, subjected to the action of resilient means (16) which presses it to engage teeth (17) on said sleeve (11) in order to prevent its rotation, said pin being disengageable by means of a tool (19). A joint according to claim 1, characterized in that said pin projects circumferentially relative to said sleeve (11), the body of the joint female element, (10) being provided with a hole(18) through which a tool (19) can reach said pin in order to move it, opposing the force exerted by said spring (16), and can disengage said sleeve (11). A joint according to claim 2, characterized in that said sleeve (11) on the joint female element (3) and said ring (5) on the joint male element have matching configurations, for permitting said ring (5) to slide but not to rotate relative to said sleeve (11). A joint for plasma arc cutting torches according to claim 2, characterized in that it comprises: a fixed ring (10); a body (8) with an external thread (6) to be fixed to generator wall (9), inside said ring (10); a sleeve (11) being provided inside ring (10), for rotation around the axis of said body (8), said sleeve having teeth on its inward edge; a pin (15), which is subjected to the action of resilient means (16) pressing it to engage teeth (17) on the inward edge of said sleeve (11); a ring (5) which is fitted on the joint male element (1) and may be screwed on said fixed element (3), said ring having means (7) engaging, by rotating, said sleeve (11).

Inventors: GIUSEPPE ZIGLIOTTO, GIUSEPPE, ZIGLIOTTO
Applicants: TRAFIMET SPA, TRAFIMET S.P.A.
Application year: 1996
Main classification: H01R13
IPC codes: H01R13, H01R43, H05H1