Title of Invention

" AN ELECTRONIC SYSTEM FOR MEASUREMENT OF GAP BETWEEN THE ROLLS OF A HOT REVERSIBLE BLOOMING MILL IN STEEL PLANTS"

Abstract The invention provides an electronic system for measurement of gap between the rolls of a hot reversible blooming mill in steel plants characterised in that the system comprises two encoders acting as opto-electronic transducers v/hich are mechanically coupled by a coupler to the extension shaft of a DC motor for producing signal pulses of number correspending to the degree of rotation of the extension shaft ,and supplying the same in tv/o channels to tv/o buffer stages meant; for shaping the signal pulses received in said tv/o channels to one Electronic Processing Unit meant for processing the shaped signal pulses received from the said tv/o buffer stages, and supplying the output signals to each of tv/o Digital Display Units, one Analogue Dial Indicator, one Alarm Unit, one Data Acquisition System and one Diagnostic Test Routine, v/hich are connected to the output of the Electronic Processing Unit, v/hich is configured and designed around 8085 Microprocessor with interfaces IC 8253 having three counters/timers v/hich can measure upto 1 MHz clock pulses and IC 8255 having thrree 8 bit ports which can be defined as input and output ports and output interface of 4-20 mA, Reference: Figures l, 2 and 3 of the accompanying drawings
Full Text The present invention relates to an electronic system for measurement of gap between the rolls of a hot reversible blooming mill in steel plants.
The two rolls in a hot blooming mill are rotatable both in clockwise and anti-clockwise directions for conducting the rolling operations in both directions, i.e. in the forward and backward. Hence these mills are called reversible mills. It is required to measure and control the gap between the rolls at a correct level continuously during the rolling operations to produce the required size and shape of the rolled products. For this purpose, the roll gap is adjusted by driving a screw by a DC motor through a gear assembly
In the existing system for measurement of roll gap the shaft of a dial indicator having a long arm and a short arm like a clock is coupled to the extension shaft of a. DC motor through a reducer gear mechanism of complex construction, containing many mechanical parts, which is damaged frequently because of heavy vibrations and jerking transferred to it from the rolls rotating rapidly in reversible directions. It requires considerable time to repair or replace the damaged gear mechanism with loss of production in the mill. Moreover, there being no electrical output available from the existing dial indicator, it is not possible to provide the digital measure of the roll gap at a distance and computerised data acquisition for the mill control purpose.
The object of the present invention is to provide an electronic system to eliminate the use of the complex reducer gear mechanism of the dial indicator of the existing system.
The other object is to provide both analogue and digital indications of the roll gap, and data acquisition system for controlling the mill operation
In the invented system an incremental Optical Shaft Encoder acting as opto-electronic transducer is coupled directly to the extension shaft of the DC motor without using the reducer gear mechanism of the existing system, for sensing the position of the rolls. The electrical pulses obtained at the output of the encoder is supplied to a buffer stage for shaping and processing of the pulses which are then supplied to an electronic Processing Unit (EPU) for converting the pulses into data corresponding to the roll gap and displaying the data on the dial of an analogue indicator as well as two digital display units. The EPU provides also necessary signals for actuating alarms in case of
any malfunctioning of the system,diagnostic test routines for fault finding and data acquisition for control of the mill operations.
Thus the invention provides an electronic system for measurement of gap between the rolls of a hot reversible blooming mill in steel plants, characterised in that the system comprises two encoders acting as opto-electronic transducers and being mechanically coupled by coupler to the extension shaft of DC motor to produce signal pulses of number corresponding to the degree of rotation of extension shaft and supplying the same in two channels, two buffer stages for shaping the signal pulses received in two channels, one electronic processing unit (EPU) for processing the shaped signal pulses received from the two buffer stages, and supplying the output signals to each of two digital display units, one analogue dial indicator, one Alarm unit, one Data Acquisition System (DAS) and one Diagnostic Test Routine (DTR), which are connected to the output of the EPU
The invented system is described fully and particularly in a unrestricted manner with
reference to the accompanying drawings in which
Figure-1 is a schematic sectional side view of a blooming mill with an encoder mounted
thereon ; Figure-2 is a block diagram showing the main functional unit of the invented system; Figure-3 is the circuit diagram of the buffer stage used,
Refining to Fig. 1 encoder (1) is connected mechanically to the shaft (2) of motor (3) by means of coupler (4) The shaft of motor is coupled to driving screw (5) through gear assembly (5A) and washer (6)„The top roll (7) and bottom roll (8) are fitted between chuck (9) above and block (10) below at a gap (11) between the rolls, which is adjusted by driving the screw with the motor through the gear assembly. The motor is totally enclosed and mounted at the mill top. Its forward motion increases the roll gap and backward motion decreases the roll gap.
Referring to Fig. 2 two encoders (1A and 1B) have been coupled to the extension shaft of the motor to provide signal pulses in two channels (A and B), which are shaped by two buffer stages (12A and 12B). The shaped pulses from the output of the buffer stages are supplied to electronic processing unit (EPU) (13)
When the shaft of the encoder is rotated by the motor electrical pulses are generated, the number of which is proportional to the degree of rotation of the encoder shaft. The
number of pulses generated per rotation of the encoder shaft is 500. The encoder is provided with a built in direction logic. Apart from the pulses generated corresponding to the degree of rotation of encoder shaft, compensation pulses are generated at the time of change of direction of rotation of the encoder shaft. The compensation pulses are either added to or subtracted from the pulses generated by the rotation of the encoder shaft depending on upward or downward movement of the rolls.
Referring to Figs. 2 and 3, the buffer stages for the two channels A and B carrying respectively the output signals of encoders 1A and 1B provide shaped output pulses separately for the upward and downward movement of the top roll corresponding to an increase and decrease of the gap between the rolls
EPU (13) is configured and designed around 8085 Microprocessor and is provided with interfaces IC 8253 and IC 8255, and control circuitry. IC 8253 has three counters / timers which can measure upto 1 MHz clock pulses. IC 8255 has 1 MHz three 8 bit ports which can be defined as input or output ports. A 4-20 mA output interface is provided as a part of EPU.
The signals of A and B channels of encoders are processed in the buffer stage. The output of the buffer stage contains two channels of pulses. One channel for up-count when the rolls are moving in the forward direction and the other channel is for down count when the rolls are moving in the reverse direction The up count pulses are counted in a one counter of IC 8253 The down count pulses are counted in the second counter of same IC 8253. At every instant the difference between the present count and the previous count of the last instant is found in both the counters. The net up count value is added to the net count value and the net down count value is subtracted from the net count value. The net value of the counts thus obtained is multiplied by a predetermined factor to obtain the gap between the rolls, which is displayed in the two digital display units (14 and 15)
EPU provides also a command signal to dial indicator (16) for driving the pointer arms of the dial indicators by actuating a stepper motor housed in the dial indicator, which has two arms, one being long and the other being short,one full rotation of the long arm corresponds to a gap between the rolls equal to 100 mm, Twelve rotations of the long arm cause one rotation of the short arm. The dial of the indicator is graduated in 100 divisions and has therefore a least count of 1 mm.
EPU supplies signals to Alarm Unit (17) having four programmable relay outputs, for use as a stand-by limit switch actuated by the position of the rolls. EPU provides also an analogue output signal to interface the Data Acquisition System (DAS) (18) for control of the blooming mill operations and a Diagnostic Test Routine (DTR) (19) for finding the fault developed in the system
The indications of EPU are calibrated against the direct measurement of the gap between the rolls.
The gap between the rolls has been measured by using both the invented and the existing systems. The test results are presented in Table-I from which it is noted that the results of the two systems are in close agreement
The invented system has however the following advantageous features over the existing system: -
1. The use of the complex gear mechanism of the dial indicator has been eliminated to prevent frequent damage of the same and consequent loss in production.
2. Both digital and analogue indications of the roll gap are provided.
3. Data Acquisition System (DAS) is provided for control of mill operations and Diagnostic Test routine (DTR) is provided for fault finding.
Table-I
Comparative Results of Measurements Using the Invented System and the Existing System
(Table Removed)






We Claim :-
1. An electronic system for measurement of gap between the rolls of a hot reversible blooming mill in steel plants, characterised in that the system comprises two encoders (1A and 1B) acting as opto-electronic transducers and being mechanically coupled by coupler (4) to the extension shaft (2) of DC motor (3) to produce signal pulses of number corresponding to the degree of rotation of extension shaft (2) and supplying the same in two channels (A and B), two buffer stages (12A and 12B) for shaping the signal pulses received in two channels (A and B), one Electronic processing Unit (EPU) (13) for processing the shaped signal pulses received from the two buffer stages, and supplying the output signals to each of two digital display units (14 and 15), one analogue dial indicator (16), one Alarm unit (17), one Data Acquisition System (DAS) (18) and one Diagnostic Test Routine (DTR) (19), which are connected to the output of the EPU
2. The system as claimed in claim 1, wherein the EPU is configured and designed around 8085 Microprocessor with interfaces IC 8253 and IC 8255 and output interface of 4-20 mA.
3. The system as claimed in claim 2, wherein IC 8253 has three counters / timers which can measure upto 1 MHz clock pulses
4. The system as claimed in claim2, wherein IC 8255 has three 8 bit ports which can be defined as input and output ports
in claim 1,
5. The system as claimed/in claim 1, wherein the analogue dial indicator is graduated in 100 divisions and has a least count of 1 mm.
6. An electronic system for measurement of gap between the rolls of hot reversible
blooming mill in steel plants, substantially as herein described and illustrated in
the accompanying drawings.

Documents:

653-del-1999-abstract.pdf

653-del-1999-claims.pdf

653-del-1999-complete specifiction (granted).pdf

653-del-1999-correspondence-others.pdf

653-del-1999-correspondence-po.pdf

653-del-1999-description (complete).pdf

653-del-1999-drawings.pdf

653-del-1999-form-1.pdf

653-del-1999-form-19.pdf

653-del-1999-form-2.pdf

653-del-1999-form-3.pdf

653-del-1999-gpa.pdf


Patent Number 246301
Indian Patent Application Number 653/DEL/1999
PG Journal Number 08/2011
Publication Date 25-Feb-2011
Grant Date 23-Feb-2011
Date of Filing 29-Apr-1999
Name of Patentee STEEL AUTORITY OF INDIA LTD.,
Applicant Address RESEARCH & DEVELOPMENT CENTRE FOR IRON & STEEL, GOVT. OF INDIA ENTERPRISE, ISPAT BHAWAN, LODHI ROAD, NEW DELHI-110003, INDIA.
Inventors:
# Inventor's Name Inventor's Address
1 RAMESH CHANDRA THAKUR RDCIS,SAIL, RANCHI,INDIA.
2 DEVULAPALLI SURYANARAYANA MURTY RDCIS,SAIL, RANCHI,INDIA.
3 KUNDAN PRAKASH RDCIS,SAIL, RANCHI,INDIA.
4 DEEPANKAR SENGUPTA RDCIS,SAIL, RANCHI,INDIA.
5 GANTI MAHAPATRUNI DAKSHINA MURTY RDCIS,SAIL, RANCHI,INDIA.
6 SUDHAKER JHA RDCIS,SAIL, RANCHI,INDIA.
7 KOLLURU SRIRAMA MURTY BSP/SAIL, INDIA.
8 MITADRU RAY BSP/SAIL, INDIA.
PCT International Classification Number G01R/00
PCT International Application Number N/A
PCT International Filing date
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 NA