| CLAIMS 1. A semi-automatic electromechanical apparatus for testing and checking a water-cooled MIG-, TIG-, and plasma-welding torch with co-axial cable comprising, in' combination: I. means for integral verification of the leakages of water in the cooling circuit of the torch and of the flow efficiency; II. means for verification of gas leakages or temporary absence of gas in the gas circuit; III. means for verification of the functionality of the pushbutton control; IV. means for verification of the dispersions towards the secondary circuit of the pushbutton-control cable; V. means for verification of accidental contact between the pilot cable of the plasma-welding torch towards the current-carrying cable; and VI. means for verification of the integrity of the copper plait of the current-carrying cable and the pilot cable; said means for integral verification of the leakages of water in the cooling circuit and for verification of gas leakages or temporary absence of gas in the gas circuit being pneumatic means; said means for verification of the functionality of the pushbutton control, for verification of the dispersions, for verification of the accidental contact, and for verification of the integrity of the copper plait being electrical means. 2. The apparatus according to the preceding claim characterized in that said pneumatic means comprise: - an inlet flow switch (FL5) , designed to detect the minimum passage of 10 1/min, as well as to close the contacts for turning on a pair of LEDs (Z2); ., - an air/gas-inlet flow meter (FL2), designed to determine an amount of passage defined according to the user manual in the testing circuit, equipped with a regulation valve and connected to the outlet of said flow switch (FL5) ; - a first manometer (Nl) , connected to the outlet of said air/gas flow meter (FL2) ; - a first pressure switch (Ul) calibrated at 0.4 bar, connected to the outlet of said air/gas flow meter (FL2) ; - three attachment-selection taps, each of which is connected to the outlet of said air/gas-inlet flow meter (FL2) and is designed to be connected to a purposely provided test connector (BT) by means of a corresponding attachment of a known type for insertion in series of the torch; - a water-inlet flow meter (FLl) , equipped with a regulation valve, connected to the outlet of said flow switch (FL5) , designed to detect the minimum passage of 10 1/min, as well as to close the contacts for turning on said pair of LEDs (Z2) ; - a non-return valve (VA) , connected to the outlet of the water-inlet flowmeter (FLl) for safeguarding its fluid tightness over time; - a second pressure switch (U2) calibrated at 1.8 bar, connected to the outlet of said non-return valve (VA) ; - a second manometer (N2) , connected to the outlet of said non-return valve (VA) ; at the outlet of said non-return valve (VA) and downstream of said second pressure switch (U2) and said second manometer (N2) there being connectable the delivery line -to the torch by known fast-coupling means/ - a discharge tap (RS) , which can be connected to the return line of "the torch; - a first, four-way, distributor (Dl) , which, being connected to the outlet of the non-return valve (VA) , to the pressure switch (U2) , to the manometer (N2) and to the delivery attachment, is designed to distribute the air in these elements; - a second, six-way, distributor (D2), which, being connected to the outlet of the air/gas flow meter (FL2), to the pressure switch (Ul) , to the manometer (Nl) , and to the attachment-selection taps (Rl, R2, R3) , is designed to distribute the air in these elements; - a further air/gas flow meter (FL3) , which, being connected to the outlet of said test connector (BT) , is designed to detect the flow of air at outlet from the nozzle of the torch to be tested; and - a further flow switch (FL4) , which, being connected to the outlet of said further air/gas flow meter (FL3) , is designed to detect a minimum passage of air of 10 1/min. 3. The apparatus according to the preceding claim, characterized in that it comprises means for light signalling of a fault, which are connected to the pressure switch (Ul, U2) and preferably comprise at least one LED. 4. The apparatus according to Claim 1 characterized in that said electrical means comprise a first 24-Vdc low-voltage circuit (Cl) , designed to signal visually, by means of LEDs, the good state of the pushbutton-control cable, and a second circuit (C2), appropriately connected to the first circuit (Cl) , there circulating in said second circuit, in the event of fault, a high current, approximately 210 A, at a low voltage, approximately 1.2 V, to measure the state of the copper plait. 5. The apparatus according to the preceding claim, characterized in that the first circuit (Cl) comprises: - supply means, which include an auxiliary supply transformer (TL2), the d.c. current of which is rectified by a diode-bridge card and are connected to a low-voltage line; - two relays connected in parallel: a first relay (CRl) , designed to activate a preferably coloured LED, via a contact of a normally open type, and a second relay (CR2) , designed to supply a power transformer (TLl) of the second circuit (C2) via a further contact of a normally open type; - two pressure switches (Tl, T2), appropriately calibrated for signalling possible obstructions due to an accumulation of air in the circuits; - a plurality of manual selectors (Sl, S2, S3) connected in parallel, each of which is designed to be connected to a PLASMA attachment (Al) of a MECHAFIN type present in the second circuit (C2) and is equipped with nine radial pins and a power fitting at the centre, said attachment being used for TIG- and PLASMA-welding torches: a first selector (Sl) , which is designed to select, according to the model of torch, a return signal from the torch inserted in said PLASMA attachment (Al) , and can be switched, thanks to the pins present in the attachment itself, so that the selector (S2) will supply a signal that can be switched in the nine pins of the attachment, which enters the wiring of the torch, passes through the pushbuttons and/or the safety contacts, and returns in another pin of the PLASMA attachment (Al) , according to the wiring of the torch, - a second selector (S2) , designed to provide the supply for all the LEDs, and a third selector (S3) , designed to select the return signal for closing the first and second relays (CRl, CR2) so as to energize the coils of the latter; a plurality of visual warning means, preferably coloured LEDs, each of which is designed to signal a fault: a first, preferably green, LED (V) for signalling the integrity of the pushbutton-control cable, - a second, preferably yellow, LED (G) for signalling an overpressure in the cooling circuit, - a third, preferably blue, LED (B) for signalling the inefficiency of closing of the safety contacts and of other contacts, - a fourth, preferably red, LED (R) , designed to signal an accidental contact of one of the two wires of the pushbutton control of the torch with respect to the current-carrying cable or to the parts connected thereto; and - at least one transistor (Ql) , designed to amplify the dispersions between the power transformer (TLl) of the second circuit (C2) and the auxiliary transformer (TL2) of the first circuit (Cl) ; in the event of a fault, the current traverses the resistance between the base and the emitter of said transistor (Ql) and passes from the first circuit (Cl) to the second circuit (C2) , causing turning-on of the LED (R) . 6. The apparatus according to the preceding claim, characterized in that the second circuit (C2) comprises: a power transformer (TLl) ; a further transformer (TA) , designed to transduce the possible short circuit between a first terminal (T7) and a second terminal (PO) of said second circuit (C2); a digital ammeter (AD) , connected to said transformer (TA) for reading the amperage between said first and second terminals (T7, PO); a plurality of further manual selectors connected in parallel, designed to be connected to the PLASMA attachment of a MECHAFIN type (Al) : a first selector (S4) and a second selector (S5) , designed to select the pilot circuit of the plasma-welding torch; and a plurality of attachments of a known type different from one another, designed to be connected to the torch to be tested and to the test connector (BT) : a EURO attachment (A2) used for MIG-welding torches, a DINSE attachment (A3) used for TIG-welding torches, as well as the PLASMA attachment (Al) of a MECHAFIN type, used for TIG- and PLASMA-welding torches. 7. The apparatus according to the. preceding claim, characterized in that, as an alternative to the single transistor (Ql) , a pair of transistor is provided connected in parallel. 8. The apparatus according to Claim 6, characterized in that it comprises a plurality of pushbuttons : - a first pushbutton or test pushbutton (pi) to be connected in parallel to auxiliary connectors (AUX) and to the fixed contacts of the known attachment of the EURO type (A2) of the second circuit (C2), as well as to the second and third selectors (S2, S3) of. the first circuit (Cl) to destine to the pins of the MECHAFIN attachment (Al) the right connection of the pushbutton of the torch to be tested; - a second pushbutton (p2) for carrying out a check on an accidental contact between the pilot cable of the plasma-welding torch towards the current-carrying cable, designed to disconnect the brushes with which the first and second selectors (S4, S5) of the second circuit (Cl) are equipped from said first terminal (PO) deriving from the transformer (TLl) , and to switch said brushes to a further terminal (2) of the first circuit (Cl) deriving from the transformer (TL2), it thus being obtained that, once the pilot circuit of a torch has already been selected via the selectors (S4, S5) , a contact between the pilot cable and the current-carrying cable, connected to the terminal (PO) of the MECHAFIN attachment (Al) will turn on the LED (R) owing to the contact between the terminal (PO) and the pin of the attachment provided for- testing of the torch, selected by the selectors (S4, S5) ; and - a third pushbutton (p3) , which is the pushbutton of the torch to be tested. 9. The apparatus according to Claim 5, characterized in that the fourth LED (R) has the anode connected to the emitter of the transistor (Ql) , whilst the cathode is connected to the auxiliary transformer (TL2) . 10. The apparatus according to Claim 8, characterized in that the transistor (Ql) has the collector connected to the second circuit (C2) via the second pushbutton (p2) in a resting position so that a possible contact between the transformer (TL2) and said circuit (C2), or else between the transformer (TL2) and said terminal (T7) to the test connector (BT) , will cause turning-on of the LED (R) . |
TORCHES WITH CO-AXIAL CABLE OF VARIOUS LENGTHS
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The present invention relates to the sector of MIG-, TIG-, and plasma-welding torches, and more specifically to an innovative apparatus for verifying the state of efficiency of said torches, with particular reference to control of the fluid tightness of the pipes and verification of the wiring.
At present, both in the production and above all in the repair of welding torches there are used separately: water pumps for verification of the pipes; multimetres for measuring the continuity of the various wiring; and gases and expendable materials used for testing.
The above traditional methodologies raise problems, such as deposits and residue of water in the cooling circuits, lack of guarantee against any drawbacks that may derive from parts that cannot be visually inspected, and the considerable time taken for traditional testing and troubleshooting .
The main purpose of the invention is to overcome said drawbacks by means of a single apparatus that is able to provide guarantees of precision, reduction of the working times, and execution of all the checks required.
The present invention enables verification, with a single apparatus using compressed air and electric power, of the state of welding torches, executing all the measuring operations that verify good functionality thereof.
This eliminates the need to use the welding generator, gas and water, thus reducing considerably the times for checks and the amount of expendable materials linked thereto and moreover enabling verification of the parts that cannot be inspected visually, with the result that a higher degree of precision and guarantee is achieved.
The above has been obtained, according to the invention, by providing a single apparatus comprising, in combination: means for verification of the integrity and good operation of the gas-supply circuit and of the corresponding controls, means for checking the integrity and good operation of the electrical circuit and of the
. corresponding controls, as well as means for checking the
; integrity and good operation of the cooling-water circuit and corresponding controls. A better understanding of the invention will emerge from the ensuing detailed description, with reference to the attached plates of drawings, which illustrate a preferred embodiment thereof purely by way of non-limiting example . In the drawings:
Figure 1 illustrates an example of MIG-MAG welding according to the known art;
Figure 2 illustrates the pneumatic part of the invention; and Figure 3 illustrates the electrical part of the invention.
The torch is an accessory of the welding machine, from which it receives all the necessary supplies for normal operation. With reference to Figure 1, MIG-MAG welding is an arc-welding process: this means that the base metal and the deposited metal are molten by an electric arc.
The principle of MIG-MAG welding and operation of the torch are substantially the following: the electric arc 1 strikes between the piece to be welded and a metal wire 2, which advances continuously to replace the metal that melts. The wire functions as electrode and as deposited metal; it is wound on a spool and supplied to the torch by a roller wire-feed unit 4, which pushes it in a wire-guide liner that forms " part of the co-axial cable (or harness of cables) 5 as far as the torch 6.
The electrical energy for the arc 1 is supplied by a generator 7, whilst the welding current reaches the wire through the contact tip 8 of the torch 6. The latter is normally connected to the positive pole of the generator 7, whilst the piece to be welded is connected to the negative pole: the circuit closes when the arc 1 strikes.
The protective gas 9, which has the purpose of protecting the wire 2, the arc 1, and the weld bath 11 from the ambient air, comes out of the nozzle 10 that surrounds the contact tip 8.
The protective gas may be inert, i.e., not participate in the processes that take place in the bath 11, or else be active. Precisely according to the type of gas used (inert or active) , the welding process is referred to as MIG (Metal Inert Gas) or else MAG (Metal Active Gas) welding.
Another currently known arc-welding process is the so-called TIG (Tungsten Inert Gas) welding.
In this case, unlike the foregoing processes, the electrode is not consumable, and the deposited metal, if necessary, is supplied manually by the operator. In the case of TIG welding, the weld zone is again protected by inert gas, and the electric arc strikes between the metal parts to be welded and the tungsten electrode . For all the welding techniques so far described it is preferable to provide for cooling of the torch.
The plasma-welding torch is similar to the ones referred to above but serves for cutting sheet metal. Its characteristic is that of being supplied by a temporary 200-Vdc voltage present between the current-carrying cable and the pilot cable. In the current-carrying cable an approximately 2000-3000-V high-frequency circuit enables development of a pilot arc sufficient to keep it active during the cutting process. These known welding apparatuses, as also those for cutting of sheet metal, such as for example the plasma-welding torch, require periodic maintenance and checks on their state of efficiency and conservation, both for guaranteeing the quality of the welding processes and for guaranteeing the safety of the workers that use them. In the light of what has been said above, the present invention is substantially constituted by a single apparatus comprising, in combination:
I. means for integral verification of the leakages of water in the cooling circuit of the torch and flow efficiency; II. means for verification of gas leakages or temporary absence of gas in the gas circuit; III. means for verification of the functionality of the pushbutton control; IV. means for verification of the dispersions towards the secondary circuit of the pushbutton-control cable;
V. means for verification of accidental contact between the pilot cable of the plasma-welding torch towards the current-carrying cable; and
VI . means for verification of the integrity copper plait of the current-carrying cable and the pilot cable. The pneumatic part comprises:
- an inlet flow switch FL5, designed to detect the minimum passage of 10 1/min, as well as to close the contacts for turning on a pair of LEDs designated by Z2;
- an air/gas inlet flow meter FL2, designed to determine an amount of passage defined according to the user manual in the testing circuit, equipped with a regulation valve and connected to the outlet of said flow switch FL5;
- a first manometer Nl, connected to the outlet of said air/gas flow meter FL2;
- a first pressure switch Ul calibrated at 0.4 bar, connected to the outlet of said air/gas flow meter FL2;
- three attachment-selection taps, each of which is connected to the outlet of said air/gas inlet flow meter FL2 and is designed to be connected to a purposely provided test output or connector BT, which is preferably tapered, by means of a corresponding attachment of a known type, for insertion in series of the torch:
- a first tap Rl, which can be connected to the torch by means of a EURO A2 attachment of a known type;
- a second tap R2, which can be connected to the torch by means of a W A4 connector of a known type;
- a third tap R3, which can be connected to the torch S- by means of a known PLASMA Al attachment of a MECHAFIN type;
- a water-inlet flow meter FLl, equipped with a regulation valve, connected to the outlet of said flow switch FL5, designed to detect the minimum passage of 10 1/min, as well as to close the contacts for turning on a pair of LEDs designated by Z2;
- a non-return valve VA, connected to the outlet of the water-inlet flow meter FLl for safeguarding its fluid tightness over time;
- a second pressure switch U2 calibrated at 1.8 bar, connected to the outlet of said non-return valve VA;
- a second manometer N2, connected to the outlet of said non-return valve VA; at outlet from said non-return valve VA and downstream of said second pressure switch U2 and said second manometer N2 the delivery can be connected to the torch by known fast-coupling means;
- a discharge tap RS, which can be connected to the return line of the torch;
- a first four-way distributor Dl, which, being connected to the outlet of the non-return valve VA, to the pressure switch U2, to the manometer N2, and to the delivery attachment, is designed to distribute the air in these elements;
- a second six-way distributor D2, which, being connected to the outlet of the air/gas flow meter FL2, to the pressure switch Ul, to the manometer Nl, and to the attachment-selection taps Rl, R2 and R3, is designed to distribute the air in these elements;
- a further air/gas flow meter FL3, which, being connected to the outlet of said test connector BT, is designed to detect the flow of air at outlet from the nozzle of the torch to be tested; and
- a further flow switch FL4, which, being connected to the outlet of said further air/gas flow meter FL3, is designed to detect a minimum passage of air of 10 1/min. According to the present invention, to make the integral verification of the leakages of water in the cooling circuit of the torch and of the flow efficiency referred to in point I, the procedure is described in what follows. Keeping the discharge tap RS closed, via the regulation valve with which the water-inlet flow meter FLl is equipped, a certain amount of air is introduced into the delivery pipe until the nominal operating pressure indicated by a manometer N2 is obtained. At this point, by closing said regulation valve, if the cooling circuit is intact, the pressure within the torch, indicated by the manometer N2, must remain constant, whereas, if there are leakages, said pressure will decrease. By re-opening the discharge tap RS the air that has remained in the cooling circuit will be vented into a purposely provided containment tray W with possible deposits of previous residual liquids.
At this point, it is envisaged to keep the discharge tap RS open and to open the valve of the flow meter FLl, there thus being obtained circulation of a few litres of air per minute (to be defined according to the type of torch) , displayed by the flow meter FLl: according to the invention, if the cooling circuit of the torch is not free, an overpressure is created inside it, which is detected both by the manometer N2 itself and by a pressure switch U2 calibrated at 1.8 bar, designed to signal the fault visually by light-warning means, preferably comprising at least one coloured LED.
The check just described, in addition to being particularly simple to make, also presents the advantage that the air, having a smaller density than water, finds the possible ways of escape more easily; hence even extremely small leakages are identified.
In other words, the first element in which air flows is the flow switch FL5. From this, the air is then distributed to the air/gas-inlet flow meter FL2 and to the water-inlet flow meter FLl.
It is important to make sure that connected to the outlet of the non-return valve VA are also fast-coupling means, designed to be connected to the inlet pipe of the cooling circuit of the torch.
By closing the discharge tap RS and repeating the operation, there derives therefrom a pressure of accumulation in the cooling circuit that is displayed by the second manometer N2.
By reclosing the water-inlet flow meter FLl, it is possible to detect a possible leakage, which is displayed by the second manometer N2.
Present between the flow switch FL5 and the flow meters FLl and FL2 is a union wye.
According to the present invention, to carry out a check on gas leakages or temporary absence of gas referred to in the foregoing point II, the procedure is described in what follows.
By selecting the type of attachment desired and introducing into the gas circuit a certain amount of air via the gas/air-inlet flow meter FL2 and by resting the nozzle of the torch to be tested in the test connector BT, it is possible to verify visually, via the gas/air-outlet flow meter FL4, what is the amount of air coming out thereof, thus identifying the presence of leakages or otherwise. The amount of air detected by the flow meter FL3 depends upon the model of torch to be tested and in particular upon the length of said torch. The value of the amount of air detected is compared with the values appearing in a table that can be annexed to a user manual.
If the amount of air detected by the flow meter FL3 is the same as that introduced by the flow meter FL2, this indicates that there are no leakages.
Possible obstructions will be indicated by the pressure switch Ul by light-signalling means, preferably comprising at least one coloured LED.
According to the invention, the advantage lies in the fact of not using gas and of obtaining an immediate measurement . Description of the electrical part
The electrical part includes two circuits: a first 24-Vdc low-voltage circuit Cl, designed to signal visually, by means of LEDs, the good state of the pushbutton-control cable, and a second circuit C2 appropriately connected to the first one, in which, in the event of fault, a high current (approximately 210 A) circulates at low-voltage (approximately 1.2 V) to measure the state of the copper plait .
The first circuit Cl comprises:
- supply means, which include an auxiliary supply transformer TL2, the d.c. current of which is rectified by a diode-bridge card (not illustrated) and which are connected to a low-voltage line;
- two relays connected in parallel: a first relay CRl, designed to activate a preferably coloured LED, via a contact of a normally open type, and a second relay CR2, designed to supply a power transformer TLl of the second circuit C2 via a further contact of a normally open type;
- two pressure switches Tl, T2, appropriately calibrated for signalling possible obstructions due to an accumulation of air in the circuits;
- a plurality of manual selectors Sl, S2, S3 connected in parallel, each of which is designed to be connected to a PLASMA Al attachment of a MECHAFIN type present in the second circuit C2 and is equipped with nine radial pins and a power fitting at the centre, said attachment being used for TIG- and PLASMA-welding torches:
- a first selector Sl, designed to select, according to the model of torch, a return signal from the torch inserted in said PLASMA Al attachment, which can be switched, thanks to the pins present in said attachment, so that the selector S2 will supply a signal that can be switched in the nine pins of the attachment, enters the wiring of the torch, passes through the pushbuttons and/or the safety contacts, and returns into another pin of the PLASMA Al attachment, according to the wiring of the torch; - a second selector S2, designed to provide the supply for all the LEDs; and
- a third selector S3, which is designed to select the return signal for closing the relays CRl and CR2 thus energizing the coils of the latter;
- a plurality of LEDs, preferably coloured, each of which is designed to signal a fault: a first LED V, preferably green, for signalling the integrity of the pushbutton-control cable, a second LED G, preferably yellow, for signalling an overpressure in the cooling circuit, a third LED B, preferably blue, for signalling the inefficiency of closing of the safety contacts and of other contacts, a fourth LED R, preferably red, designed to signal an accidental contact of one of the two wires of the pushbutton control of the torch with respect to the current-carrying cable or to the parts connected thereto;
- at least one transistor Ql, designed to amplify the dispersions between the power transformer TLl of the second circuit C2 and the auxiliary transformer TL2 of the first circuit Cl; in the event of fault, ■ the current traverses the resistance between the base and the emitter (preferably approximately 15 K) of said transistor Ql, and passes from the first circuit Cl to the second circuit C2, causing turning-on of the LED R. As regards the pins of the torches, each manufacturer ' connects said pins (pushbuttons and/or safety contacts) according to the generator to be used, and hence the pushbuttons and/or safety contacts can be on any pin, for example between the first pin and the ninth, between the first pin and the seventh, between the fourth and the third, etc.
According to the invention, it is possible to envisage as an alternative to the single transistor Ql a pair of transistors connected in parallel. According to the invention, a plurality of pushbuttons are provided:
- a first pushbutton or test pushbutton pi to be connected in parallel to auxiliary connectors AUX and to the fixed contacts of the known attachment of a EURO A2 type present in the second circuit C2, as well as to the selectors S2 and S3 in order to destine to the pins of the MECHAFIN Al attachment the right connection of the pushbutton of the torch to be tested;
- a second pushbutton p2 for verifying accidental contact between the pilot cable of the plasma-welding torch towards the current-carrying cable, designed to disconnect the brushes with which the selectors S4 and S5 are equipped from one terminal PO deriving from the transformer TLl and to switch said brushes to a terminal 2 of the circuit Cl deriving from the transformer TL2, it thus being obtained that, since the pilot circuit of a torch has already been selected via the selectors S4 and S5, a contact between the pilot cable and the current-carrying cable, connected to the terminal PO of the MECHAFIN Al attachment, will turn on a LED R owing to the contact between the terminal PO and the pin of the attachment provided for testing of the torch, selected by the selectors S4 and S5; and
- a third pushbutton p3, which is the pushbutton of the torch to be tested.
By closing the contacts of the pushbuttons pi and p3, the coils of the two relays CRl CR2 are energized, it thus being obtained that the first relay CRl turns the LED V on, whilst the second relay CR2 supplies the power transformer
TLl of the circuit C2.
As an alternative to closing of the contacts of the pushbuttons, it is possible to insert in the auxiliary connectors AUX any pushbutton or else shortcircuit the • selectors S2 and S3.
By means of the auxiliary connectors AUX it is possible to test the pushbuttons of torches that are without attachments for control of the pushbutton ' and are only equipped with free wires that are to be connected to said auxiliary connectors.
In order to signal possible faults due to an accumulation of air during the flow tests, the two pressure switches Tl and T2 are calibrated at 0.4 bar and 1.8 bar, respectively. A possible fault brings about turning-on of the LED G.
The return signal from the torch comes to engage a pin of the MECHAFIN Al attachment selected by the selector Sl, according to the model of torch, and hence brings about turning-on of the LED B. Said LED B is connected to the brush of the selector Sl and is activated by Sl when closing of the safety contacts is not efficient.
,The second circuit C2 comprises: - a power transformer TLl;
- a further transformer TA, designed to transduce the possible short circuit between two terminals T7 and PO of said circuit C2;
- a digital ammeter AD, connected to said transformer TA for reading the amperage between the aforesaid terminals of the circuit;
- a plurality of further manual selectors, connected in. parallel, designed to be connected to the PLASMA attachment of a MECHAFIN Al type: a first selector S4 and a second selector S5, designed to select the pilot circuit of the plasma-welding torch;
- a plurality of attachments of a known type different from one another, designed to be connected to the torch to be tested and to the test connector BT: a EURO A2 attachment used for MIG-welding torches, a DINSE A3 attachment used for TIG-welding torches, as well as the PLASMAAl attachment of a MECHAFIN type used for TIG- and PLASMA-welding torches.
As has already been mentioned, circulating in the second circuit C2 is a high current at an extremely low voltage so that the reduction of the current-carrying copper cable, on account of fraying or oxidation of the copper fibres themselves, will cause a drop of voltage across the power transformer TLl proportional to the section and to the length of the current-carrying cables (copper plaits) used. The amperage across T7 and PO, and their consequent shortcircuiting, is then transduced by the further transformer TA and read by the digital ammeter ' AD connected thereto .
The second circuit C2 is connected to the power parts of said attachments, which are constituted substantially by a body having a central part, as in the case of the EURO or MECHAFIN attachments, or a radial part, as in the case of the DINSE attachment, made of insulating material.
A fault causes turning-on of said second circuit C2 and is caused by the passage of current that occurs between the pushbutton-control pins and the power circuit.
The anode of the red LED R is connected to the emitter of the transistor Ql, whilst the cathode is connected to the auxiliary transformer TL2, and the collector of said transistor Ql is connected to the second circuit C2 via the second pushbutton p2 in a resting position so that a possible contact between the transformer TL2 and said circuit C2 or else between the transformer TL2 and a terminal T7 at the test connector BT will cause turning-on of the red LED R.
The selectors S3 and S4 are designed to set up in the pins of the PLASMAAl attachment the connection of the pilot circuit of the plasma-welding torches.
By keeping the second pushbutton p2 in a resting position and repeating the verification referred to in point V above it is possible to determine the state of the pilot circuit. . In order to determine the state of the pilot circuit, it is sufficient to insert the torch into the apparatus, after the selectors S4 and S5 have previously been selected, and then shortcircuit the ends of the torch in the test connector BT.
By pressing the pushbutton p2, the brushes S4 and S5 are disconnected from the terminal PO deriving from the power transformer TLl and switched to the terminal 2 of the circuit Cl deriving from the transformer TL2. In this case, possible currents due to accidental contacts between the current-carrying cable and the pilot circuit, flowing in the transistor Ql, causing turning-on of the red LED R. Characteristics of the power transformer TLl Secondary: 1 V 210 A.
According to the present invention, to carry out a check on the functionality of the pushbutton control referred to in the previous point, the procedure is described in what follows.
To test the integrity of the pushbutton-control cable, it is envisaged to press the pushbutton of the torch so as to close a purposely provided low-voltage circuit (described hereinafter) , which issues a visual signal of the good state thereof via an appropriate coloured LED, preferably a green LED V. In the case of faults, the circuit activates a coloured (preferably red) alarm LED R.
The advantage is represented by the simplicity and effectiveness of the test and by the fact that the test can be repeated at any moment.
According to the present invention, to carry out a check on the dispersions towards the secondary circuit of the pushbutton-control cable referred to in the previous point IV, the procedure is described in what follows.
The above check is made automatically once the torch has been inserted into the adapter, or else by pressing the pushbutton: said check serves to signal a possible accidental contact between one of the two wires of the pushbutton control of the torch and the current-carrying cable or the parts connected thereto. If it were so, a small current having a value comprised between 20 mA and 10 A will flow towards it, and its presence will be signalled by a coloured, preferably red, LED R.
The above measurement is of great importance because on some types of generators the fault leads to damage of cards or other control apparatus .
According to the present invention, to carry out a check on an accidental contact between the pilot cable of the plasma-welding torch towards the current-carrying cable, referred to in the previous point V, the procedure is described in what follows.
This check is determined by pressing the pushbutton p2 and serves to detect a dispersion between the two elements in any point of the torch. Also in this case, a possible dispersion activates a coloured, preferably red,
LED R.
Once said pushbutton has been pressed, the transistor Ql will amplify even weak dispersions currents.
According to the present invention, to carry out a check on the integrity of the copper plait of the current-carrying cable and the pilot cable referred to in the previous point VI, the procedure is described in what follows .
The above operation enables verification of whether the cable carrying all the welding current is still intact; i.e., it has more or less all the characteristics for guaranteeing proper operation.
The operation of causing circulation in the second circuit C2, via a power transformer TLl, a high current at an extremely low voltage is simple, and is obtained by resting the contact tip 8 of the torch in a purposely provided test connector BT and by pressing the pushbutton p3; the measurement will be displayed by the digital ammeter AD, the value of which will be compared with the values of the measurements contained in a table, which are the measurements made at a previous date via a standard torch of a similar type.
In the case where the pushbutton p3 were not to function, the pushbutton pi can execute the functions of the pushbutton p3. Said test connector BT is equipped with a metal part insulated from the body, via which the transformer TLl is shortcircuited by resting the end portion of the torches.
The advantage is represented by the fact that it is possible to identify cables that during the welding process would have a short duration, and hence make a preventive replacement of said cables.
Technical description of the attachments
The attachments listed are of a known type.
EURO ATTACHMENT: this is an attachment used for (continuous wire) MIG-welding torches, which has a single body entirely made of brass with a thread for supporting the torch, connected to a shank for connection to the generator and through inserts provided for insulated contacts (pins), passage of the protective gas, and welding wire.
DINSE ATTACHMENT: this is an attachment used for TIG-welding torches, which has a single body made of brass with fast coupling for supporting the torch, a thread for connection of the generator cable, painted with insulating radial substrate. MECHAFIN ATTACHMENT: this is an attachment used for TIG- and PLASMA-welding torches and has a body made of PVC, including the thread for supporting the torch, with the conductive power part located at the centre, provided with a hole for enabling passage of gas; the contact pins are ■ arranged radially on the part made of PVC.
As has already been mentioned, the advantages of the present invention consist in the guarantee of precision, in the reduction of the working times, and in the possibility of carrying out all the checks with a single apparatus .
The present invention has been described and illustrated in a preferred embodiment, but it is evident that any person skilled in the sector may make technically equivalent modifications and/or replacements thereto, without thereby departing from the sphere of protection of the present industrial patent right.