CLIAMS:We Claim:
1. A cooling system for X-Ray generator of automatic gauge control for closed loop thickness control at the exit of hot rolled strips , comprising
generator assembly comprising generator tank having insulating oil;
said insulating oil having means for indirect cooling involving water body surrounding the generator tank alongwith copper tube for circulating chilled water for cooling of the tank enabling stabilizing the generator tank temperature to a fixed value irrespective of the rate of rolling.

2. A cooling system for X-Ray generator as claimed in claim 1 wherein level of said water body is variable.

3. A cooling system for X-Ray generator as claimed in anyone of claims 1 or 2 wherein level of the water body is determined considering influence of hot rolled metal.

4. A cooling system for X-Ray generator as claimed in anyone of claims 1 to 3 comprising means to regulate the volume of coolant by regulating water flow therethrough.

5. A cooling system for X-Ray generator as claimed in anyone of claims 1 to 4 wherein said X-ray generator comprises voltage multiplier and X-Ray tube assembly immersed in insulating oil in said generator tank.

6. A cooling system for X-Ray generator as claimed in anyone of claims 1 to 5, wherein the X Ray generator is adapted to operate upto at 150KV with the temperature of generator block at constant and below 60°C.

7. A cooling system for X-Ray generator as claimed in anyone of claims 1 to 6 adapted such that all possible high voltage discharge path is blocked to avoid any generator component failure.

8. A cooling system for X-Ray generator as claimed in anyone of claims 1 to 7, which is free of water/moisture ingression to the insulating oil inside the tank.

Dated this the 15th day of May, 2014

Anjan Sen
Of Anjan Sen & Associates
(Applicants Agent)
,TagSPECI:FILED OF THE INVENTION

The present invention relates to a cooling system for X-Ray generator used in X-Ray thickness gauge for the Automatic Gauge Control for desired close loop thickness control in hot rolling of flat products in steel plants. More particularly, the present invention is directed to providing a cooling system for X-Ray generator adapted to arrest measurement drift due to rise in temperature of the tube and for preventing voltage multiplier failure at the exit of hot rolling finishing stand, thus ensuring precise thickness control of the rolled products.

BAKGROUND OF THE INVENTION

In hot rolling of flat products, Thickness Gauge plays pivotal role for the close loop thickness control. At Hot Strip Mill of the applicants, X-Ray thickness gauge is used to generate the input signal for the Automatic Gauge Control with accuracy of ±10µ and response time as close as 4 millisecond. To achieve the same a very precise & controlled X-Ray is required which in turn significantly depends upon the temperature of voltage multiplier and X-Ray tube assembly. While operating up to 150 KV, oil immersed tube assembly is heated gradually also the whole assembly is under influence of hot strip at around 900°C. To stabilize the temperature to a fixed value irrespective of the rate of rolling, suitable cooling arrangement should come into effect. Any variation of X-Ray generator temperature significantly changes ionization current and in turn affects thickness measurement. As the generator assembly is immersed into high insulating oil, any moisture/water droplets can make short path for high voltage discharge and there by failure of multiplier components.

In conventional practice, to keep the temperature of generator block at constant and below 60°C, a copper tube with chilled water circulation was immersed in the insulating oil. As the generator works on 150 KV, mere change in insulation of oil, due to moistures/ingression of water droplets blow off the generator.

Due to improper cooling arrangement, failure rate of generator was very high. Also due to temperature variation, drift in measurement and in turn gauge failure occurred frequently. Temperature profile of the insulating oil tank was assessed for the drift in measurement. During failure of generator, after opening the insulating oil tank multiple arc path(dark patches) was found. After analyzing the insulating oil, traces of water was detected.

There has been therefore a need in the art of gauge thickness control using X-ray generator based signal generator for automatic closed loop thickness control of hot rolled sheets to provide a cooling system which would ensure precise thickness measurement by desired temperature control and reliable operation of the X-Ray generator in a safe and reliable manner.

OBJECTS OF THE INVENTION

The basic object of the present invention is directed to provide a cooling system for X-Ray generator used in X-Ray thickness gauge for close loop thickness control in hot rolling of flat products in steel plants to ensure desired precise control of thickness of rolled products.

A further aspect of the present invention is directed to a cooling system for X-Ray generator used in X-Ray thickness gauge for close loop thickness control in hot rolling of flat products adapted to arrest temperature rise of voltage multiplier and X-Ray tube assembly within safe limit to ensure desired thickness control.

A still further aspect of the present invention is directed to a cooling system for X-Ray generator used in X-Ray thickness gauge for close loop thickness control in hot rolling of flat products which would avoid temperature variation and resulting drift in measurement and in turn avoid gauge failure while rolling hot strips.

A still further aspect of the present invention is directed to a cooling system for X-Ray generator used in X-Ray thickness gauge for close loop thickness control in hot rolling of flat products wherein failure of generator due to change in insulation of oil, due to moistures/ingression of water droplets blow off the generator is avoided.

A still further aspect of the present invention is directed to a cooling system for X-Ray generator used in X-Ray thickness gauge for close loop thickness control in hot rolling of flat products which would stabilize the temperature of X-Ray thickness gauge to a fixed value irrespective of the rate of rolling.

A still further aspect of the present invention is directed to a cooling system for X-Ray generator used in X-Ray thickness gauge for close loop thickness control in hot rolling of flat products which would avoid significantly changes in ionization current to ensure precise thickness measurement with desired accuracy.

SUMMARY OF THE INVENTION

The basic aspect of the present invention is thus directed to providing a cooling system for X-Ray generator of automatic gauge control for closed loop thickness control at the exit of hot rolled strips , comprising
generator assembly comprising generator tank having insulating oil;

said insulating oil having means for indirect cooling involving water body surrounding the generator tank alongwith copper tube for circulating chilled water for cooling of the tank enabling stabilizing the generator tank temperature to a fixed value irrespective of the rate of rolling.

A further aspect of the present invention is directed to a cooling system for X-Ray generator wherein level of said water body is variable.

A still further aspect of the present invention is directed to said cooling system for X-Ray generator wherein level of the water body is determined considering influence of hot rolled metal.

A still further aspect of the present invention is directed to said cooling system for X-Ray generator which comprises means to regulate the volume of coolant by regulating water flow therethrough.

Yet another aspect of the present invention is directed to said cooling system for X-Ray generator wherein said X-ray generator comprises voltage multiplier and X-Ray tube assembly immersed in insulating oil in said generator tank.

A further aspect of the present invention is directed to said cooling system for X-Ray generator, wherein the X Ray generator is adapted to operate upto at 150KV with the temperature of generator block at constant and below 60°C.

A still further aspect of the present invention is directed to said cooling system for X-Ray generator adapted such that all possible high voltage discharge path is blocked to avoid any generator component failure.

Advantageously also, said cooling system for X-Ray generator according to the present invention is free of water/moisture ingression to the insulating oil inside the tank.

The objects and advantages of the present invention are described hereunder in greater details with reference to the following accompanying non limiting illustrative drawings.

BRIEF DESCRIPTION OF THE ACCOMPANYING FIGURES

Figure 1: is the schematic front view and top view of the X-Ray generator tank showing the conventional cooling arrangement of the X-Ray generator involving a copper tube with chilled water circulation immersed in the insulating oil.

Figure 2: is the schematic front view and the top view of the cooling system for X-Ray generator according to the present invention involving a water jacket around the generator cooled with chilled water carrying tube wound on the outside.

DETAILED DESCRIPTION OF THE INVENTION WITH REFERENCE TO THE ACCOMPANYING FIGURES

The present invention is directed to a cooling system for X-Ray generator used in X-Ray thickness gauge for the Automatic Gauge Control for desired close loop thickness control in hot rolling of flat products in steel plants. More particularly, the present invention is directed to providing a cooling system for X-Ray generator adapted to arrest measurement drift due to rise in temperature of the tube and for preventing voltage multiplier failure at the exit of hot rolling finishing stand, thus ensuring precise thickness control of the rolled products.

Reference is first invited to the accompanying Figure 1 that schematically illustrate the front view and top view of the X-Ray generator tank showing the conventional cooling arrangement involving a copper tube with chilled water circulation immersed in the insulating oil. In this conventional X-ray thickness gauge, to keep the temperature of generator block at constant and below 60°C, a copper tube with chilled water circulation was immersed in the insulating oil. But, due to improper cooling arrangement, failure rate of generator was very high. Also due to temperature variation, drift in measurement and in turn gauge failure occurred frequently. Temperature profile of the insulating oil tank was assessed for the drift in measurement. During failure of generator, after opening the insulating oil tank multiple arc path(dark patches) was found. After analyzing the insulating oil, traces of water was detected. As the generator works on 150 KV, mere change in insulation of oil, due to moistures/ingression of water droplets blow off the generator.

An improved cooling system for X-Ray generator of thickness gauge has thus been provided by way of the present invention which eliminate the above stated limitations of the conventional X-ray gauge and ensure arresting temperature rise/variation to ensure correct thickness measurement at the exit of hot strip mill.

Reference is now invited to the accompanying Figure 2 that show the schematic front view and the top view of the cooling system for X-Ray generator according to the present invention involving a water jacket around the generator cooled with chilled water carrying tube wound on the outside.

A detailed cooling arrangement for the X-Ray generator has been designed to stabilize the tank temperature and to eliminate all possibilities of water/moisture ingression to the insulating oil. The copper tube inside the oil tank was removed and a water body placed surrounding the generator tank which is in turn is cooled with chilled water circulated through copper tubes wound outside the tank. The temperature profile of the oil tank was monitored after statuary generator heating. The level of the water body was determined considering influence of hot rolled metal. As indirect cooling for the insulating oil is incorporated, volume of coolant increased suitably by regulating water flow. The measurement drift was observed for different rolling rate. As all possible high voltage discharge path is blocked, no component failure was observed during substantial period of trial of the invented system.

It is thus possible by way of the present invention to developing a cooling system for X-Ray generator for X-Ray thickness gauge employed for automatic gauge control for desired close loop thickness control of hot rolled strips, which is capable to arrest temperature variation of generator tank to ensure correct thickness measurement of hot rolled strips in a reliable manner avoiding generator/component failure with longer operating life.
We Claim:
1. A cooling system for X-Ray generator of automatic gauge control for closed loop thickness control at the exit of hot rolled strips , comprising
generator assembly comprising generator tank having insulating oil;
said insulating oil having means for indirect cooling involving water body surrounding the generator tank alongwith copper tube for circulating chilled water for cooling of the tank enabling stabilizing the generator tank temperature to a fixed value irrespective of the rate of rolling.

2. A cooling system for X-Ray generator as claimed in claim 1 wherein level of said water body is variable.

3. A cooling system for X-Ray generator as claimed in anyone of claims 1 or 2 wherein level of the water body is determined considering influence of hot rolled metal.

4. A cooling system for X-Ray generator as claimed in anyone of claims 1 to 3 comprising means to regulate the volume of coolant by regulating water flow therethrough.

5. A cooling system for X-Ray generator as claimed in anyone of claims 1 to 4 wherein said X-ray generator comprises voltage multiplier and X-Ray tube assembly immersed in insulating oil in said generator tank.

6. A cooling system for X-Ray generator as claimed in anyone of claims 1 to 5, wherein the X Ray generator is adapted to operate upto at 150KV with the temperature of generator block at constant and below 60°C.

7. A cooling system for X-Ray generator as claimed in anyone of claims 1 to 6 adapted such that all possible high voltage discharge path is blocked to avoid any generator component failure.

8. A cooling system for X-Ray generator as claimed in anyone of claims 1 to 7, which is free of water/moisture ingression to the insulating oil inside the tank.

Dated this the 15th day of May, 2014

Anjan Sen
Of Anjan Sen & Associates
(Applicants Agent)

ABSTRACT

TITLE: A COOLING SYSTEM FOR X-RAY GENERATOR OF AUTOMATIC GAUGE CONTROL OF HOT ROLLED STRIPS.

The present invention relates to a cooling system for X-Ray generator used in X-Ray thickness gauge for the Automatic Gauge Control for desired close loop thickness control in hot rolling of flat products at the exit of hot rolling finishing stand in steel plants. More particularly, the present invention is directed to providing a cooling system for X-Ray generator adapted to arrest measurement drift due to rise in temperature of the tube generator assembly comprising generator tank with insulating oil having means for indirect cooling involving water body surrounding the generator tank alongwith copper tube for circulating chilled water for cooling of the tank enabling stabilizing the generator tank temperature to a fixed value irrespective of the rate of rolling. Moreover, the system also prevents voltage multiplier failure and water/moisture ingression to the insulating oil inside the tank, thus ensuring precise thickness control of the rolled products in a reliable manner.
(Figure 2)