Title of Invention

VOLTAGE TRACKING DEVICE FOR ROBOTIC WELDING STATION FOR VEHICLES

Abstract

A voltage tracking device for robotic welding station for vehicles comprising a PLC with timer connected to a robot controller, a welding controiier connected to the robot controller, a welding transformer whose primary is connected to the weiding controller and secondary is connected to a welding gun, a voltage step down transformer whose primary winding ends are connected across the primary winding ends of the welding transformer and secondary winding ends are connected to the PLC through a relay and the relay's normally open contact, the PLC being further connected to an audio visual indicator. The audio visual indicator comprises a hooter and a lamp or a hooter and liquid crystal display.

Full Text

FORM 2 THE PATENTS ACT, 1970 As amended by The Patents (Amendment) Act of 1999 and As amended by The Patents (Amendment) Act of 2002 COMPLETE SPECIFICATION (SEE SECTION 10, RULE 13) TITLE Voltage tracking device for robotic welding station for vehicles APPLICANTS Tata Motors Limited, Bombay House, 24 Homi Mody Street, Hutatma Chowk, Mumbai -400001, Maharashtra, india, an Indian Company . INVENTOR Under Section 28(2) Adii Keki Bala, Tata Motors Limited, Manufacturing Division CVBU, Pimpri, Pune - 41101B, Maharashtra, india, an Indian National The following specification particularly describes the nature of this invention and the manner in which it is to be performed : original 982/mum/2003 GRANTED 20-09-2004 FIELD OF INVENTION This invention relates to a voltage tracking device for robotic welding station for vehicle. PRIOR ART In an assembly line in automobile industry, side frames, underframe and roof of vehicles are weided together at certain predetermined spots at the framing station. The remaining spots on the vehicles are welded at the robotic welding station which comprises a PLC (Programmable Logic Controller) connected to a robot controller, a welding controller connected to the robot controller and a welding transformer whose primary is connected to the welding controller and secondary is connected to a welding gun i.e. robot The PLC decides when welding is to be carried out and gives a command to the robot controller. On receipt of the command, the robot controller gives a command to the weiding controller which in turn gives a voltage signal to the welding transformer. The weiding transformer is a step down transformer and steps down the voltage and feeds it to the welding gun which does the welding at the remaining predetermined spots on the vehicles. In such a welding station there are chances of vehicles passing by without being fully welded i.e. all the remaining spots being weided and the welding cycle getting over as if weiding had been fully completed. Since the station is unmanned and fully automatic it is not possible to check whether all the remaining spots in the vehicles have been weided and the fault goes undetected. If welding is not carried out at all the remaining predetermined spots joints between the above parts of the vehicles may become weak which is undesirable. This results in rework i.e. rewelding by repeating the cycle. 2 OBJECTS OF THE INVENTION An object of the invention is to provide a voltage tracking device for robotic welding station for vehicles, which ensures that welding has been carried out at all the remaining predetermined spots in the vehicles going past the station thereby avoiding rework of the vehicles i.e. rewelding by repeating the cycle. Another object of the invention is to provide a voltage tracking device for robotic welding station for vehicles, which is simple in construction and easy to operate. Another object of the invention is to provide a voltage tracking device for robotic welding station for vehicles, which is economical. DETAILED DESCRIPTION OF INVENTION According to the invention there is provided a voltage tracking device for robotic welding station for vehicles comprising a PLC with timer connected to a robot controller, a welding controller connected to the robot controller, a welding transformer whose primary is connected to the welding controller and secondary is connected to a welding gun, a voltage step down transformer whose primary winding ends are connected across the primary winding ends of the welding transformer and secondary winding ends are connected to the PLC through a relay and the relay's normally open contact, the PLC being further connected to an audio visual indicator. The following is a detailed description of the invention with reference to the accompanying sole Fig 1 which is a block diagram of a voltage tracking device for robotic welding station for vehicles according to an embodiment of the invention. 3 The device 1 of the invention comprises a PLC with timer marked 2 connected to a robot controller 3. 4 is a welding controller connected to the robot controller. 5 is a welding transformer whose primary 6 is connected to the welding controller and secondary 7 is connected to a welding gun marked 8.9 is a voltage step down transformer whose primary and secondary winding are marked 10 and 11, respectively. The primary winding ends of the voltage step down transformer are connected across the primary winding ends of the welding transformer. The secondary winding ends of the voltage step down transformer are connected to the PLC through a relay 12 and the relay's normally open contact 13. The PLC is further connected to an audio visual indicator marked 14. The timer in the PLC is set for a particular period of time i.e. time interval corresponding to duration of each instance of spot welding. The PLC decides when welding is to be carried out and gives a command to the robot controller. Simultaneously the timer in the PLC goes on. The robot controller gives a command to the welding controller which in turn gives a command in the form of a voltage signal to the welding transformer. The welding transformer steps down the output voltage from the welding controller and feeds it to the welding gun which does the welding on the vehicle (not shown). Simultaneously the voltage from the primary of the welding transformer is tapped to the primary of the voltage step down transformer and induced in the secondary thereof. The voltage is stepped down and fed to the relay. The relay's contact closes and allows a voltage to the PLC. The PLC senses this voltage at the end of the time interval corresponding to an instance of spot welding. This indicates that voltage had actually appeared across the welding transformer after PLC had given the weld command to the robot controller and welding had taken place. The PLC will only then give the next weld command to the robot controller. If no voltage appears across the welding transformer 4 after the PLC had given the weld command to the robot controller then the relay is not actuated and the contact remains open and no voltage flows to the PLC. The PLC senses the absence of voltage at the end of the time interval and actuates the audio / visual indicator thereby alerting an operator at a nearby station to stop the welding cycle. The device of the invention thus ensures that welding has been carried out at ail the remaining spots in the vehicles going past the welding station thereby avoiding rework, i.e. rewelding by repeating the cycle. The device of the invention is also simple in construction and easy to operate. The cost of the components of the device is low. Therefore, the device is economical. The audio visual indicator may be a hooter and lamp or LCD (liquid crystal display), it may comprise only visual indicator such as lamp or LCD or audio indicator such as hooter. Such variations of the invention are to be construed and understood to be within the scope of the invention. 5 WE CLAIM : 1. A voltage tracking device for robotic welding station for vehicles comprising a PLC connected to a robot controller a welding controller connected to the robot controller, a welding transformer whose primary is connected to the welding controller and secondary is connected to a welding gun. characterized in that said PLC is having a timer, a voltage step down transformer whose primary winding ends are connected across the primary wincing ends of the welding transformer and secondary winding ends are connected to the PLC through a relay and the relay's normally open contact, the said PLC being further connected to an audio visual indicator. 2. A voltage tracking device as claimed in claim i, wherein the audio visual indicator comprises a hooter and a lamp or a hooter and liquid crystal display. 3. A voltage tracking device for robotic welting station for vehicles substantially as herein described particular^ with reference to Rg 1 of the accompanying drawings. 6 Dated this isth day of September 2003

Documents:

982-mum-2003-abstract(20-09-2004).doc

982-mum-2003-abstract(20-09-2004).pdf

982-mum-2003-cancelled page(20-09-2004).pdf

982-mum-2003-claims(granted)(20-09-2004).doc

982-mum-2003-claims(granted)-(20-09-2004).pdf

982-mum-2003-correspondence(21-10-2005).pdf

982-mum-2003-correspondence-ipo(13-01-2004).pdf

982-mum-2003-drawing(20-09-2004).pdf

982-mum-2003-form 1(19-09-2003).pdf

982-mum-2003-form 19(28-10-2003).pdf

982-mum-2003-form 2(granted)(20-09-2004).doc

982-mum-2003-form 2(granted)-(20-09-2004).pdf

982-mum-2003-form 3(23-01-2004).pdf

982-mum-2003-form 8(28-10-2003).pdf

982-mum-2003-power of attorney(01-10-2003).pdf

982-mum-2003-power of attorney(23-01-2004).pdf

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