Title of Invention	POWER TRACKING DEVICE FOR INDUCTION HARDENING MJACHINE
Abstract	A power tracking device (1) for induction hardening machine comprising a controlled rectifier (2) connectable to a three phase high voltage source of the order of 440 V; a controlled inverter (3) connected to the said controlled rectifier; a tank circuit (4) comprising an inductor (5) and capacitor (6) in parallel configuration connected to the said controlled inverter; a control circuit (7) connected to the said controlled rectifier and the said controlled inverter; a PLC (Programmable Logic Controller) (8) connected to the normally open contactors in series (13 and 14) of relays (15 and 16) connected to the outputs (9 and 10) of a pair of corresponding voltage comparators (11 and 12) and the said PLC further connected to one of the inputs (17 and 18) of each of the voltage comparators (11 and 12) and to the control circuit, the other input (19) of one of the voltage comparators being connected to the control circuit and the other input (20) of the other voltage comparator being connected to a reference voltage source (21) and the PLC being further connected to an audio/visual indicator(22).

Title of Invention

POWER TRACKING DEVICE FOR INDUCTION HARDENING MJACHINE

Abstract

A power tracking device (1) for induction hardening machine comprising a controlled rectifier (2) connectable to a three phase high voltage source of the order of 440 V; a controlled inverter (3) connected to the said controlled rectifier; a tank circuit (4) comprising an inductor (5) and capacitor (6) in parallel configuration connected to the said controlled inverter; a control circuit (7) connected to the said controlled rectifier and the said controlled inverter; a PLC (Programmable Logic Controller) (8) connected to the normally open contactors in series (13 and 14) of relays (15 and 16) connected to the outputs (9 and 10) of a pair of corresponding voltage comparators (11 and 12) and the said PLC further connected to one of the inputs (17 and 18) of each of the voltage comparators (11 and 12) and to the control circuit, the other input (19) of one of the voltage comparators being connected to the control circuit and the other input (20) of the other voltage comparator being connected to a reference voltage source (21) and the PLC being further connected to an audio/visual indicator(22).

Full Text	FORM 2 THE PATENTS ACT, 1970 (39 of 1970) COMPLETE SPECIFICATION (SEE SECTION 10, RULE 13) TITLE Power tracking device for induction hardening machine APPLICANTS Tata Motors Limited, Bombay House, 24 Homi Mody Street, Hutatma Chowk, Mumbai - 400001, Maharashtra, India, an Indian company INVENTOR Under Section 28(2) Joshi Prasanna Hanamant, Tata Motors Limited, Manufacturing Division CVBU, Pimpri, Pune 411018, 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 : FIELD OF INVENTION This invention relates to a power tracking device for induction hardening machine. PRIOR ART induction hardening of components such as crank shaft, shifter fork or ring gear is carried out in an Induction hardening machine which comprises a controlled rectifier connectabie to a three phase high voltage source of the order of 440 V, a controlled inverter connected to the controlled rectifier, a tank circuit comprising an inductor and capacitor in parallel configuration connected to the controlled inverter, a control circuit connected to the controlled rectifier and controlled inverter and a PLC (Programmable Logic ControHer) connected to the control circuit. The job to be hardened is held mechanically within the inductor at the centre thereof. The PLC determines the power to be supplied to the inductor and the extent to which the job is to be heated and gives a command in the form of a voltage signal to the control circuit which in turn gives a corresponding signal to the controlled rectifier and controlled inverter. The controlled rectifier and controlled inverter generate the high frequency voltage to be fed to the tank circuit. During operation of the machine, the high frequency current flowing through the inductor induces a voltage in the job. This voltage sets up a large current in the job thereby heating the job and hardening it. Due to reasons such as malfunctioning of the controlled rectifier and / or controlled inverter or change in the impedance of the tank circuit or misalignment of the job within the inductor or change in the air gap between the inductor and the job the power delivered to the job at times falls below the requisite level and the job is not heated to the desired temperature and the desired level of hardening of the job is not achieved. OBJECTS OF INVENTION An object of Invention is to provide a power tracking device for induction hardening machine which ensures heating and hardening of job to the desired level. Another object of the invention is to provide a power tracking device for induction hardening machine which is simple in construction and easy to operate. Another object of the invention is to provide a power tracking device for induction hardening machine which is economical. DETAILED DESCRIPTION OF THE INVENTION According to the invention there is provided a power tracking device for induction hardening machine comprising a controlled rectifier connectable to a three phase high voltage source of the order of 440 V, a controlled inverter connected to the controlled rectifier, a tank circuit comprising an inductor and capacitor in parallel configuration connected to the controlled inverter, a control circuit connected to the controlled rectifier and controlled inverter, a PLC (Programmable Logic Controller) connected to the outputs of a pair of voltage comparators through normally open contactors and relays and further connected to one of the inputs of each of the voltage comparators and to the control circuit, the other input of one of the voltage comparators being connected to the control circuit and the other input of the other voltage comparator being connected to a reference voltage source 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 Fig 1 which is a block diagram of a power tracking device for induction hardening machine according to an embodiment of the invention. The power tracking device 1 as illustrated in Fig 1 of the drawings comprises a controlled rectifier 2 connectabie to a three phase high voltage source of the order of 440 V (not shown). 3 is a controlled inverter connected to the controlled rectifier. 4 is a tank circuit comprising an inductor 5 and capacitor 6 in parallel configuration connected to the controlled inverter. 7 is a control circuit connected to the controlled rectifier and controlled inverter. 8 is a PLC (Programmable Logic Controller) connected to the outputs 9 and 10 of a pair of voltage comparators 11 and 12 through normally open contactors 13 and 14 and relays 15 and 16, respectively. The PLC is further connected to one of the inputs 17 and 18 of the voltage comparators 11 and12, respectiveiy and to the control circuit. The other input 19 of one voltage comparator 11 is connected to the control circuit and the other input 20 of the other voltage comparator 12 is connected to a reference voltage source 21. The PLC is further connected to an audio/visual indicator marked 22. A job 23 to be heated and hardened is held mechanically within the inductor at the centre thereof in known manner using known means. The PLC determines the power to be supplied to the inductor and the extent to which the job is to be heated and hardened and gives a command in the form of a voltage signal to the control circuit. The control circuit gives a corresponding command to the controlled rectifier and controlled inverter which in turn generate the required power and feed it to the tank circuit. Simultaneously, the voltage signal from the PLC to the control circuit also appears at the inputs 17 and 18 of the voltage comparators 11 and 12. A voltage signal corresponding to the command given by the control circuit to the controlled rectifier and controlled inverter is also fed to the input 19 of the voltage comparator 11 by the control circuit. The voltage comparator 11 compares the incoming voltage signals. Due to reasons such as malfunctioning of the controlled rectifier and / or controlled inverter or change in the impedance of the tank circuit or misalignment of the job within the inductor or change in the air gap between the inductor and the job if the difference between the input signals from the PLC and control circuit differ beyond a set value, the voltage comparator 11 gives out a signal which actuates the relay IS. The relay 15 in turn closes the corresponding contactor 13 and allows a voltage to flow to the PLC. The PLC senses this voltage and stops the cycle and activates the audio/visual indicator thereby alerting an operator to rectify the fault. Due to malfunctioning of the PLC if the voltage signal given by the PLC falls below a reference voltage set in the reference voltage source 21 the voltage comparator 12 gives out a signal which actuates the relay 16. The relay 16 in turn closes the corresponding contactor 14 and allows a voltage to flow to the PLC. The PLC senses this voltage and stops the cycle and activates the audio/visual indicator thereby alerting an operator to rectify the fault. The device of the invention thus ensures that if there is any malfunctioning of the induction hardening machine x \it is immediately detected enabling corrective messures to be taken thereby enabling the machine to deliver the required level of power to the job to be heated and hardened. This ensures heating and hardening of the job to the required level. 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. WE CLAIM 1. A power tracking device (1) for induction hardening machine comprising a controlled rectifier (2) connectable to a three phase high voltage source of the order of 440 V; a controlled inverter (3) connected to the said controlled rectifier; a tank circuit (4) comprising an inductor (5) and capacitor (6) in parallel configuration connected to the said controlled inverter; a control circuit (7) connected to the said controlled rectifier and the said controlled inverter; a PLC (Programmable Logic Controller) (8) connected to the normally open contactors in series (13 and 14) of relays (15 and 16) connected to the outputs (9 and 10) of a pair of corresponding voltage comparators (11 and 12) and the said PLC further connected to one of the inputs (17 and 18) of each of the voltage comparators (11 and 12) and to the control circuit, the other input (19) of one of the voltage comparators being connected to the control circuit and the other input (20) of the other voltage comparator being connected to a reference voltage source (21) and the PLC being further connected to an audio/visual indicator(22). 2. A power 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 power tracking device for an induction hardening machine substantially as herein described with reference to Fig 1 of the accompanying drawings. Dated this 18th day of September 2003

Full Text

FORM 2
THE PATENTS ACT, 1970 (39 of 1970)
COMPLETE SPECIFICATION (SEE SECTION 10, RULE 13)
TITLE
Power tracking device for induction hardening machine
APPLICANTS
Tata Motors Limited, Bombay House, 24 Homi Mody Street, Hutatma Chowk, Mumbai - 400001, Maharashtra, India, an Indian company
INVENTOR
Under Section 28(2)
Joshi Prasanna Hanamant, Tata Motors Limited, Manufacturing Division CVBU, Pimpri, Pune 411018, 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 :

FIELD OF INVENTION
This invention relates to a power tracking device for induction hardening machine.
PRIOR ART
induction hardening of components such as crank shaft, shifter fork or ring gear is carried out in an Induction hardening machine which comprises a controlled rectifier connectabie to a three phase high voltage source of the order of 440 V, a controlled inverter connected to the controlled rectifier, a tank circuit comprising an inductor and capacitor in parallel configuration connected to the controlled inverter, a control circuit connected to the controlled rectifier and controlled inverter and a PLC (Programmable Logic ControHer) connected to the control circuit. The job to be hardened is held mechanically within the inductor at the centre thereof. The PLC determines the power to be supplied to the inductor and the extent to which the job is to be heated and gives a command in the form of a voltage signal to the control circuit which in turn gives a corresponding signal to the controlled rectifier and controlled inverter. The controlled rectifier and controlled inverter generate the high frequency voltage to be fed to the tank circuit. During operation of the machine, the high frequency current flowing through the inductor induces a voltage in the job. This voltage sets up a large current in the job thereby heating the job and hardening it. Due to reasons such as malfunctioning of the controlled rectifier and / or controlled inverter or change in the impedance of the tank circuit or misalignment of the job within the inductor or change in the air gap between the inductor and the job the power delivered to the job at times falls below the requisite level and the job is not heated to the desired temperature and the desired level of hardening of the job is not achieved.

OBJECTS OF INVENTION
An object of Invention is to provide a power tracking device for induction hardening machine which ensures heating and hardening of job to the desired level.
Another object of the invention is to provide a power tracking device for induction hardening machine which is simple in construction and easy to operate.
Another object of the invention is to provide a power tracking device for induction hardening machine which is economical.
DETAILED DESCRIPTION OF THE INVENTION
According to the invention there is provided a power tracking device for induction hardening machine comprising a controlled rectifier connectable to a three phase high voltage source of the order of 440 V, a controlled inverter connected to the controlled rectifier, a tank circuit comprising an inductor and capacitor in parallel configuration connected to the controlled inverter, a control circuit connected to the controlled rectifier and controlled inverter, a PLC (Programmable Logic Controller) connected to the outputs of a pair of voltage comparators through normally open contactors and relays and further connected to one of the inputs of each of the voltage comparators and to the control circuit, the other input of one of the voltage comparators being connected to the control circuit and the other input of the other voltage comparator being connected to a reference voltage source 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 Fig 1 which is a block diagram of a power tracking device for induction hardening machine according to an embodiment of the invention.

The power tracking device 1 as illustrated in Fig 1 of the drawings comprises a controlled rectifier 2 connectabie to a three phase high voltage source of the order of 440 V (not shown). 3 is a controlled inverter connected to the controlled rectifier. 4 is a tank circuit comprising an inductor 5 and capacitor 6 in parallel configuration connected to the controlled inverter. 7 is a control circuit connected to the controlled rectifier and controlled inverter. 8 is a PLC (Programmable Logic Controller) connected to the outputs 9 and 10 of a pair of voltage comparators 11 and 12 through normally open contactors 13 and 14 and relays 15 and 16, respectively. The PLC is further connected to one of the inputs 17 and 18 of the voltage comparators 11 and12, respectiveiy and to the control circuit. The other input
19 of one voltage comparator 11 is connected to the control circuit and the other input
20 of the other voltage comparator 12 is connected to a reference voltage source 21. The PLC is further connected to an audio/visual indicator marked 22.
A job 23 to be heated and hardened is held mechanically within the inductor at the centre thereof in known manner using known means. The PLC determines the power to be supplied to the inductor and the extent to which the job is to be heated and hardened and gives a command in the form of a voltage signal to the control circuit. The control circuit gives a corresponding command to the controlled rectifier and controlled inverter which in turn generate the required power and feed it to the tank circuit. Simultaneously, the voltage signal from the PLC to the control circuit also appears at the inputs 17 and 18 of the voltage comparators 11 and 12. A voltage signal corresponding to the command given by the control circuit to the controlled rectifier and controlled inverter is also fed to the input 19 of the voltage comparator 11 by the control circuit. The voltage comparator 11 compares the incoming voltage signals. Due to reasons such as malfunctioning of the controlled rectifier and / or controlled inverter or change in the impedance of the tank circuit or misalignment of the job within the inductor or change in the air gap between the inductor and the job if the difference between the input signals from the PLC and

control circuit differ beyond a set value, the voltage comparator 11 gives out a signal which actuates the relay IS. The relay 15 in turn closes the corresponding contactor 13 and allows a voltage to flow to the PLC. The PLC senses this voltage and stops the cycle and activates the audio/visual indicator thereby alerting an operator to rectify the fault. Due to malfunctioning of the PLC if the voltage signal given by the PLC falls below a reference voltage set in the reference voltage source 21 the voltage comparator 12 gives out a signal which actuates the relay 16. The relay 16 in turn closes the corresponding contactor 14 and allows a voltage to flow to the PLC. The PLC senses this voltage and stops the cycle and activates the audio/visual indicator thereby alerting an operator to rectify the fault. The device of the invention thus ensures that if there is any malfunctioning of the induction hardening machine x \it is immediately detected enabling corrective messures to be taken thereby enabling the machine to deliver the required level of power to the job to be heated and hardened. This ensures heating and hardening of the job to the required level. 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.

WE CLAIM
1. A power tracking device (1) for induction hardening machine comprising a controlled rectifier (2) connectable to a three phase high voltage source of the order of 440 V; a controlled inverter (3) connected to the said controlled rectifier; a tank circuit (4) comprising an inductor (5) and capacitor (6) in parallel configuration connected to the said controlled inverter; a control circuit (7) connected to the said controlled rectifier and the said controlled inverter; a PLC (Programmable Logic Controller) (8) connected to the normally open contactors in series (13 and 14) of relays (15 and 16) connected to the outputs (9 and 10) of a pair of corresponding voltage comparators (11 and 12) and the said PLC further connected to one of the inputs (17 and 18) of each of the voltage comparators (11 and 12) and to the control circuit, the other input (19) of one of the voltage comparators being connected to the control circuit and the other input (20) of the other voltage comparator being connected to a reference voltage source (21) and the PLC being further connected to an audio/visual indicator(22).
2. A power 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 power tracking device for an induction hardening machine substantially as herein described with reference to Fig 1 of the accompanying drawings.

Dated this 18th day of September 2003

Documents:

985-mum-2003-claims(granted)-(14-01-2005).doc

985-mum-2003-claims(granted)-(14-01-2005).pdf

985-mum-2003-correspondence(14-01-2005).pdf

985-mum-2003-correspondence(ipo)-(06-02-2007).pdf

985-mum-2003-drawing(14-01-2005).pdf

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

985-mum-2003-form 19(03-11-2003).pdf

985-mum-2003-form 2(granted)-(14-01-2005).doc

985-mum-2003-form 2(granted)-(14-01-2005).pdf

985-mum-2003-form 3(18-09-2003).pdf

985-mum-2003-form 8(21-01-2004).pdf

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

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Patent Number

205266

Indian Patent Application Number

985/MUM/2003

PG Journal Number

40/2008

Publication Date

03-Oct-2008

Grant Date

23-Mar-2007

Date of Filing

19-Sep-2003

Name of Patentee

TATA MOTORS LIMITED

Applicant Address

BOMBAY HOUSE, 24 HOMI MODY STREET, HUTATMA CHOWK, MUMBAI,

Inventors:

#	Inventor's Name	Inventor's Address
1	JOSHI PRASANNA HANAMANT	TATA MOTORS LIMITED, MANUFACTURING DIVISION CVBU, PIMPRI, PUNE 411018,

PCT International Classification Number

C21D 9/60

PCT International Application Number

N/A

PCT International Filing date

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1			NA