Patent Publication Number: US-10758992-B2

Title: Handling apparatus for performing a TIG weld with regulation of speed of the fed wire

Description:
BACKGROUND 
     The subject matter of the present disclosure relates to a handling apparatus for performing a TIG weld and arc welding kit, namely a set of tools that is used to perform a manual arc welding operation. 
     A known arc welding kit comprises a welding mask and a welding tool. The welding tool comprises an electrode. During welding operations, an electric arc develops between the electrode and the welding area. 
     In a first type of arc welding, the SMAW (Shielded Metal Arc Welding), the electrode itself melts due to the heat developed by the electric arc, thus becoming the filler material in the weld. In a second type of arc welding, the TIG (Tungsten Inert Gas), the electrode is solid, and the filler material is provided separately. 
     With more detail, the kit comprises a set of sensors which can detect the main operating parameters of a welding process, namely the voltage (V), the current (A), the welding speed (W) and their combination to calculate the heat input. The welding mask can be provided with a display device so that these parameters can be shown to a welder, thereby providing him with a possibility of correcting the welding in real time. An example of this welding mask is the one shown in the U.S. Pat. No. 6,242,711 81. 
     A disadvantage of the known welding kit is that it merely provides the welder with the welding parameters. However, this does not guarantee that the welder can adapt and correct a welding that is being performed improperly. In other words, the welding operation itself still relies heavily on the manual skill of the operator. This is particularly true with respect to the welding voltage, since it is mainly determined by the distance of the electrode from the weld area. 
     SUMMARY 
     An embodiment of the invention therefore relates to a handling apparatus for performing a TIG weld. Such handling apparatus comprises a main body for holding a filler rod. The handling apparatus also comprises a feeding device attached to the main body and configured to advance the filler rod during welding. A control unit is configured to act on the feeding device and to regulate the speed of the filler rod. 
     In an embodiment, this may be advantageous in helping the welder to spread more evenly the filler material during the TIG weld. Therefore, this gives more aid to the welder in case of a TIG weld, which is one of the most difficult type of weld. 
     Another embodiment of the present invention relates to an arc welding kit. The kit comprises the above described handling apparatus. The kit also comprises a welding tool with a main body and a handle attached to the main body so that it can be held by a welder. The kit also comprises a non-consumable electrode for performing a TIG weld. The electrode is attached to the main body. An adjusting device is associated with the electrode for moving the electrode forward/backward with respect to the main body of the welding tool. The control unit is also connected to the adjusting device, and is configured to act on the adjusting device for maintaining a substantially constant distance between the electrode and a weld area. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Further details and specific embodiments will refer to the attached drawings, in which: 
         FIG. 1  is a schematic representation of an arc welding kit according to an embodiment; 
         FIG. 2  is a side sectional view of a component of the kit of  FIG. 1 ; 
         FIG. 3  is a front sectional view of the component of  FIG. 2 ; 
         FIG. 4  is a side sectional view of a component of the kit of  FIG. 1 , according to a different embodiment; 
         FIG. 5  is a side sectional view of a handling apparatus for performing a TIG weld according to an embodiment; 
         FIG. 6  is a top sectional view of the handling apparatus of  FIG. 5 ; 
         FIG. 6A  is an enlarged view of a detail of  FIG. 6 ; 
         FIG. 7  is a front sectional view of the handling apparatus of  FIGS. 5 and 6 ; 
         FIG. 8  is a front view of a further component of the kit of  FIG. 1 ; and 
         FIG. 9  is a schematic representation of the functioning of the kit of  FIG. 1 . 
     
    
    
     DETAILED DESCRIPTION 
     The following description of exemplary embodiments refer to the accompanying drawings. The same reference numbers in different drawings identify the same or similar elements. The following detailed description does not limit the invention. Instead, the scope of the invention is defined by the appended claims. 
     Reference throughout the specification to “one embodiment” or “an embodiment” means that a particular feature, structure, or characteristic described in connection with an embodiment is included in at least one embodiment of the subject matter disclosed. Thus, the appearance of the phrases “in one embodiment” or “in an embodiment” in various places throughout the specification is not necessarily referring to the same embodiment. Further, the particular features, structures or characteristics may be combined in any suitable manner in one or more embodiments. With reference to the attached drawings, with the number  1  is indicated an arc welding kit according to an embodiment of the present invention. 
     The welding kit  1  comprises a welding tool  2 , which is configured to be held by a welder. 
     The welding tool  2  comprises an electrode  3 . In one embodiment, which is used to perform a SMAW (shielded metal arc weld), shown in  FIGS. 2 and 3 , the electrode  3  is consumable. In other words, in this embodiment the electrode  3  becomes the filler material of the weld. In a second embodiment, shown in  FIG. 4 , the electrode  3  is non-consumable, thus it is used to perform a TIG (Tungsten Inert Gas) weld. 
     With additional details, the welding tool  2  comprises a main body  20 , configured to support the electrode  3 . The main body  20  is, in an embodiment, axial-symmetric, and develops mainly along a longitudinal axis “A”. A handle  21  for the welder supports the main body  20 . 
     The main body  20  has a seat  20   a  in which the electrode  3  is installed. As shown in  FIGS. 2 and 4 , the welding tool  2  is provided with bearings  22 , which are attached to the main body and located in proximity of the seat  20 , so that they can support the electrode  3  and allow it to move forward and backward. In other words, the electrode  3  can move forward and backward inside the seat  20   a  by sliding on the bearings  22 . 
     Also, the welding tool  2  comprises an adjusting device  4  associated with the electrode  3 , in order to move the electrode forward/backward with respect to the main body  20 . The adjusting device  4  comprises a wheel  23  having a central axis “C” disposed transversally and, in an embodiment, perpendicularly, to the longitudinal axis “A” of the electrode  3 , which is parallel to the axis of the main body  20 . Indeed, the main body  20  is provided with a port in which the wheel  24  is inserted. 
     In operation, the rim of the wheel  23  is in contact with the electrode  3  so that the electrode  3  can be moved along the longitudinal axis “A” by a rotation of the wheel along the central axis “C”. The adjusting device  4  also comprises a motor  24 . Such motor  24  is, in an embodiment, electric. In an additional embodiment, the motor is an electromagnetic motor, and is installed on the wheel  23  in order to actuate the wheel  23  and through it, the electrode  3 . 
     With particular reference to the SMAW welding tool  2  of  FIG. 2  please note that, in use, the wheel  23  advances overtime since the electrode  3  is consumed during welding. Therefore, the rotation speed of the motor  24  provides an overall forward movement to the electrode, and varies the rotation speed in order to adjust the distance of the tip of the electrode  3  as will be explained in a following part of the disclosure. 
     On the other hand, in the TIG welding tool  2  of  FIG. 4  the electrode  3  is not consumed during welding. Therefore, the wheel  23  is moved only to adjust the distance of the electrode  3 . 
     Also, in the embodiment of  FIG. 4  a source of inert gas is present (not shown in the drawings) in order to shield the tip of the electrode  3  and the weld area from atmospheric oxygen. This source of inert gas is by itself known to the person skilled in the art, thus will not be described in detail. The kit  1  comprises a voltage sensor  5  which is configured to detect a welding voltage “Vw” between the electrode  3  and the weld area, that is function of the distance between the end of the electrode facing the work piece and the weld area of the work piece. The voltage sensor  5  is also configured to emit a voltage signal “Vs”, which is representative of a value of the welding voltage “Vw”. Such voltage sensor  5  can be of any type known to the person skilled in the art, and therefore will not be described in detail. 
     The kit  1  also comprises a control unit  6 . In the following part of the disclosure, the control unit  6  will be described by subdividing it into a plurality of modules. Such subdivision is done for ease of description only, and in no way, should be considered as reflecting the physical structure of the control unit  6  itself. Rather, each module can be implemented as an electronic circuit on a suitable hardware support, as a software routine, subroutine or library or as both. Each module may reside on a local unit or may be distributed over a network. Also, the modules can communicate with each other either via a suitable wired or wireless protocol. 
     The control unit  6  comprises a data acquisition module  7 , which is configured to acquire the above-mentioned voltage signal “Vw”. 
     The control unit  6  also comprises a memory module  16 , which is configured to store a target voltage value “Vt”. 
     The control unit  6  also comprises an input module  17  configured to set said target voltage value “Vt” in said memory module  16 . In a particular embodiment of the invention the input module  17  can be a QR code reader. In this way, the voltage “Vt”, as well as any other parameter related to the welding process, can be read by the input module  17  on a suitably encoded QR code. 
     The control unit  6  also comprises a processing module  8 , which is configured to output an actuation signal “Sa” function of at least the voltage signal “Vs”. Also, the processing module  8  is configured to retrieve the target voltage value “Vt” and to compare it with the welding voltage value “Vw”. The actuation signal “Sa” is therefore at least in part directly proportional to the result of such comparison. With additional detail, the processing module  8  may be programmed with a PID (Proportional, Integral and Derivative) logic. Therefore, the actuation signal “Sa” may be the sum of a part directly proportional to the difference between “Vw” and Vt”, of a part proportional to the derivative of such difference and of a part proportional to the integral of such difference. Any possible combination can be used, depending on the chosen control strategy. The processing module  8  can also be configured to supply a voltage difference signal “Dv” representing the result of the difference between “Vw” and “Vt”. 
     The control unit  6  also comprises an actuation module  14  connected to the adjusting device  4 . The actuation module  14  is configured to operate the adjusting device  4  as directed by the actuation signal “Sa”. In particular, the actuation module  14  operates the motor  24  which rotates the wheel  23 . Optionally, the welding kit also comprises a welding mask  9 . Such welding mask  9  is configured to be worn by a welder during a welding process as a standard safety mask. In particular, the welding mask  9  comprises a darkened window  10  from which the welder may observe the welding process without being blinded by the intense light. 
     Additionally, the welding mask  9  is provided with a welding velocity sensor. The welding velocity sensor  11  is configured to detect a welding velocity “Wa”, and to emit a welding velocity signal “Ws” representing a value of the welding velocity “Wa”. 
     According to an embodiment of the invention, the welding velocity sensor  11  comprises a first optical sensor  12 A. The first optical sensor  12 A is in particular arranged so that, during welding operation it faces the weld area. As shown in  FIG. 8 , the first optical sensor is, in an embodiment, placed on the external surface of the welding mask  9 , over the darkened window  10 . The welding velocity sensor  11  also comprises a reference frame sensor  12 B, in an embodiment. This reference frame sensor  12 B can be any kind of sensor which is able to detect a motion within a fixed frame of reference. For example, the reference frame sensor  12 B can be an inertial sensor located on any point of the welding mask  9 . 
     With more detail, in the embodiment shown in  FIG. 8  the reference frame sensor  12 B is a second optical sensor. The reference frame sensor  12 B is therefore, in an embodiment, arranged to face a fixed reference scene in the environment, as for example the work piece part from the weld area, and placed. In an embodiment, it is placed beside the first optical sensor  12 A. In an embodiment of the invention, the sensors  12 A,  12 B are imaging cameras. 
     With additional detail, the first optical sensor  12 A is configured to detect the velocity of the welding pool relative to itself. Also, the reference frame sensor  12 B is configured to detect the velocity of the above mentioned fixed reference scene. According to one embodiment, the welding velocity sensor also comprises a velocity computing module  13  which is configured to compute the welding velocity “Wa” as a difference between the velocities detected by the second  12 B and the first optical sensor  12 A. Alternatively, the first optical sensor  12 A and reference frame sensor  12 B both transmit the respective velocities to the control unit  6 , in particular to the data acquisition module  14 . 
     The processing module  8  is also configured to compute a velocity difference between the welding velocity “Wa” and a target velocity “Wt” value, said processing unit being configured to emit a velocity difference signal “Ow” representing the result of said velocity difference. 
     Optionally, the welding mask  9  comprises a visualization device  15 . Such visualization device  15  is arranged to be easily visible by the welder during the welding process. As shown in  FIGS. 1 and 8 , the visualization device  15  is placed inside the welding mask  9 , in an embodiment on one side of the darkened window  10 . 
     With more detail, the visualization device  15  is configured to acquire the above-mentioned velocity difference signal “Dw”, thus showing a representation of the velocity difference to the welder. Similarly, the visualization device  15  can be configured to acquire the voltage difference signal “Dv” mentioned above and to show a representation of the voltage difference to the welder. 
     In an embodiment, the visualization device  15  can be configured to show an operating parameter of the welding process, such as the voltage (V), the current (A), the welding speed (W), respectively between the electrode and the weld area, or their combinations. As shown schematically in  FIG. 8 , the visualization device comprises a plurality of LEDs  26 . These LEDs are arranged in a cross, and are configured to lighten in such a way as to indicate whether the welder should go faster or slower, or if he should get nearer or farther from the weld area, in an embodiment. 
     Referring specifically to  FIGS. 5 and 6 , the kit  1  can also comprises a handling apparatus  18  for a filler rod “R”. The handling apparatus  18  comprises a feeding device  19  configured to advance the filler rod “R” during welding. 
     With additional details, the handling apparatus  18  comprises a main body  27 , configured to support the filler rod “R”. The main body  27  is, in an embodiment, axial-symmetric, and develops mainly along a longitudinal axis “B”. A handle  28  for the welder is attached to the main body  27 . In an embodiment, the handle  28  surrounds the main body  27  of the handling apparatus  18 . 
     The main body  27  has a central seat  27 A in which the filler rod “R” is placed. As shown in  FIG. 5 , the handling apparatus  18  is provided with bearings  29 , which are attached to the main body  27  and located in proximity of the central seat  27 A, to support the filler rod “R” and allow it to move forward/backward. In other words, the filler rod “R” can move forward/backward inside the seat  27 A by sliding on the bearings  29 . 
     The feeding device  19  comprises a wheel  30  having a central axis “D” disposed transversally, and, in an embodiment, perpendicularly to the longitudinal axis “B” of the main body  27 . 
     In operation, the rim of the wheel  30  is in contact with the filler rod “R” so that it can be moved along the longitudinal axis “B” by a rotation of the wheel  30  along the central axis “D”. The feeding device  19  also comprises a motor  31 . Such motor  31  is electric, in an embodiment, and is installed on the wheel  30  in order to actuate the filler rod “R”. 
     In an alternative embodiment, not shown in the drawings, the feeding device  19  comprises an electromagnetic actuation device for the filler rodn “R” instead of the wheel  30  and the motor  31 . 
     If the handling apparatus  18  is used, the processing module  8  may be configured to emit a feeding velocity signal “Sv” to the actuation module  14 . The feeding velocity signal “Sv” is proportional to a feeding velocity value “Fv”, in an embodiment. The actuation module  14  is therefore also configured to operate the feeding device  19  of the handling apparatus  18  as directed by the feeding velocity signal “Sv”. 
     Also, as shown in  FIG. 6 a   , the handling apparatus  18  comprises a control interface  32  associated with the processing module  8 . The control interface  32  is configured to emit a command signal “Cv” to the processing module  8 , so that the welder can increase or decrease the feeding velocity signal “Sa”. 
     With additional detail, the control interface  32  comprises a button  33  placed on the handle  28 . Specifically, the button  33  allows the welder to adjust the feeding velocity continuously; however, the button  33  is designed as to give a tactile feedback in the form of “clicks” at predetermined intervals so that the welder can be made aware with a certain precision of the amount that the feeding velocity is being manually increased or decreased. 
     This written description uses examples to disclose the invention, including the preferred embodiments, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims.