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 painting station for vehicle
APPLICANTS
Tata Motors Limited, Bombay House, 24 Homi Mody Street, Hutatma Chowk, Mumbai - 400001, Maharashtra, India, an Indian company
INVENTOR
Under Section 28(2)
Adil Keki Bala, Tata Motors Limited, Manufacturing Division CVBU, Pimpri, Pune 411018, Maharashtra, India, an Indian national
The following specification particularly describes and ascertains the nature of this invention and the manner in which it is to be performed :

FIELD OF INVENTION
This invention relates to a voltage tracking device for robotic painting station for vehicle.
PRIOR ART
In automobile industry vehicles are painted at a robotic painting station which comprises a PLC (Programmable Logic Controller) connected to a robot controller, a painting controller connected to the robot controller and a painting gun i.e. robot connected to the painting controller. The PLC decides when paint is to be applied on a vehicle and gives a command in the form of electrical pulses to the robot controller which in turn gives an electrical signal to the painting controller. The value of the electrical pulses corresponds to the quantity of paint to be applied on the vehicle. On receiving the electrical signal, the painting controller supplies paint to the painting gun, which applies the paint to the vehicle. In such a painting station there are chances of vehicles passing by without paint being applied over the entire vehicle surface and the painting cycle getting over as if painting had been fully completed. Since the station is unmanned and fully automatic it is not possible to check whether

vehicles have been fully painted and the fault goes undetected. This results in rework i.e repainting of the vehicles by repeating the cycle.
In another version of the robotic painting station the painting controller is connected to the painting gun through a flow meter and a control system is connected across the flow meter. The flow meter generates electrical pulses corresponding to the actual quantity of paint flowing into the painting gun therethrough and feeds them to the control system which compares the incoming electrical pulses with reference electrical pulses being generated therein corresponding to the painting command signal of the PLC. If the number of pulses received by the control system is not equal to the number of reference pulses, the control system feeds additional quantity of paint to the flow meter to compensate for the deficiency in the quantity of paint flowing through the flow meter thereby making up for the deficiency of paint. In case there are no incoming electrical pulses at all from the flow meter the control system feeds the entire quantity of paint to the flow meter corresponding to the painting command signal of the PLC. The control system is complex in construction and very expensive thereby

rendering the painting station complicated in construction and expensive,
OBJECTS OF THE INVENTION :
An object of the invention is to provide a voltage tracking device for robotic painting station for vehicle, which ensures that the vehicles going past me station are fully painted thereby avoiding rework of the vehicles i.e repainting of vehicle by repeating the cycle.
Another object of the invention is to provide a voltage tracking device for robotic painting station for vehicle, which is simple in construction and easy to operate,
Another object of the invention is to provide a voltage tracking device for robotic painting station for vehicle, which is economical.

DETAILED DESCRIPTION OF INVENTION
According to the invention there is provided a voltage tracking device for robotic painting station for vehicle comprising a PLC (Programmable Logic Controller) with timer connected to a robot controller, a painting controller connected to the robot controller and a painting gun connected to the painting controller through a flow meter, the PLC and the flow meter being looped together by an input line which rs connected fo the PLC and afeo to the ffow meter and 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 Figure 1 which is a block diagram of a voltage tracking device for robotic painting station for vehicle according to an embodiment of the invention.
The device 1 of the invention comprises a PLC with timer markeq 2 connected to a robot controller 3. 4 is a painting controller connected to the robot controller. 6 is a painting gun i.e. robot

connected to the painting controller through a flow meter 7. The PLC and the flow meter are looped together by an input line 8 which is connected to the PLC and also to the flow meter. The PLC is further connected to an audio visual indicator marked 9.
The timer in the PLC is set for a particular period of time i.e. time interval corresponding to painting duration. The PLC decides when paint is to be applied and gives the painting command to the robot controller in the form of a set number of electrical pulses corresponding to the quantity of paint to be fed to the painting gun. Simultaneously, the timer in the PLC goes on. The robot controller gives a corresponding electrical signal to the painting controller. On receiving the electrical signal, the painting controller supplies the paint to the painting gun via the flow meter and the painting gun does the painting of the vehicle (not show). The flow meter generates electrical pulses corresponding to the actual quantity of paint flowing into the painting gun therethrough and feeds them to the PLC which compares the incoming pulses with the set number of pulses given by it to the robot controller, at the end of the time interval. If the number of pulses

received by the PLC is equal to the set number of pulses given by the PLC, it is an indication that required quantity of paint flow to the painting gun had taken place after the PLC had given the painting command to the robot controller and painting had taken place. The PLC will only then give the next painting command to the robot controller. If the number of pulses received by the PLC is not equal to the set number of pulses given by the PLC, it is an indication that required quantity of paint flow to the painting gun had not taken place after the PLC had given the painting command to the robot controller and proper painting of the vehicle had not taken place. The PLC then actuates the audio visual indicator thereby alerting an operator at a nearby station to stop Ihe painting cycle. The device of the invention Ihus ensures that all the vehicles going past the painting station are fully painted thereby avoiding rework of the vehicle i.e. repainting by repeating the cycle. The device of the invention is also simple in construction and easy to operate. The cost of the device is negligible and it is, therefore, 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.

WE CLAIM
1) A voltage tracking device for robotic painting station for
vehicle comprising a PLC (Programmable Logic Controller) with timer connected to a robot controller, a painting controller connected to the robot controller and a painting gun connected to the painting controller through a flow meter, the PLC and the flow meter being looped together by an input line which is connected to the PLC and also to the flow meter and the PLC being further connected to an audio visual indicator.
2J A voltage tracking device as claimed in claim 1, 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 painting station for
vehicle substantially as herein described particularly with reference to Fig 1 of the accompanying drawings.

Dated this 18 th day of September 2003.