Title of Invention

"AN IMPROVED SENSOR LOOP FOR DETECTING AND ARRESTING LONGITUDINAL CONTINUOUS CUT IN STEEL CORD REINFORCED RUBBER CONVEYOR BELTS AND METHOD OF CONSTRUCTING THE SAME"

Abstract An improved sensor loop for detecting and arresting longitudinal continuous cut in rubber conveyor belts, being embedded in the rubber cover of the conveyor belts, and operable as a part of an electronic control system, such as herein described, characterised in that the sensor loop comprises a pair of separate endless loops (1, 2) of substantially rectangular configuration, each endless loop being made of a steel rope (1') which is pre-bent in a zig-zag/wavy pattern, and that the two ends (a, b) of the steel rope (1') forming an endless loop are joined by braiding strands (a", b') thereof.
Full Text The invention relates to an improved sensor loop for detecting and arresting longitudinal continuous cut in steel cord reinforced rubber conveyor belts and to a method of constructing the same.
The invention relates more particularly to a sensor loop which is embedded in the rubber cover of a conveyor belt having steel cord reinforcement in the longitudinal direction only.
The sensor loop according to the invention being of substantially rectangular configuration in the horizontal plane is embedded in the rubber cover of a conveyor belt in a manner so as to cover substantially the entire width of the conveyor belt by the longer sides of the sensor loop. A plurality of such sensor loops are embedded in the conveyor belt at preselected intervals along the length of the belt.
The function of the sensor loop, forming part of an electronic control system, is to permit transmission of an electromagnetic signal from a transmitter to a receiver, one/two pairs of said transmitter and receiver being installed underneath the conveyor belt one on each side of a location in the conveying path of belt, which is identified to be vulnerable to damages resulting in a longitudinal cut in the belt. When a longitudinal cut takes place in the part of the belt lying at the said vulnerable region of the conveying path and extends upto the location of the belt where the nearest sensor loop is embedded, the longitudinal sides of the sensor loop lying there are also cut, disrupting thereby the transmission of the electromagnetic signal from the transmitter to the receiver of that pair of transmitter and receiver of the electronic control system, installed ahead of the said vulnerable
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region of the conveying path in the direction of movement of belt, leading to stoppage of further movement of belt automatically by means of the electronic control system.
EP 1419982 discloses a conveyor belt with a rip detection sensor, having novelty lying in transponders (42, 44). The endless loop (36) (illustrated in Fig. 2) is formed of straight conductors (38, 42).
W002/40384 discloses a fault monitoring and sensing system, in which an electrically conductive fault responsive component extending between the two side portions of the belt is used, in the form of a loop having two end-connecting portions connected to the fault sensing circuit, and being in series with at least one capacitor and in parallel with at least one capacitor.
GB 121 6069 discloses a supervision apparatus for conveyor belts of rubber or similar material, in which electrically conductive inserts are embedded in the belt, and each insert includes two conductors, lying closely side by side or co-axially, and extending approximately over the whole width of the belt, forming part of an open-current loop or open-inductive loop. A contact is established between the two conductors of each insert when the belt is damaged.
The abovementioned prior arts are not relevant to the present invention, which relates to a sensor loop for detecting and arresting longitudinal continuous cut in rubber conveyor belts, comprising two endless loops each made of a steel wire which is pre-bent in a zig-zag/wavy pattern having the free ends of the steel wire joined by braiding of the strands thereof, instead of by soldering or brazing as conventionally done. The loops of the present invention
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are not connected directly to the electronic control system or arty components. The movement of the belt is stopped automatically when the steel wire forming a loop is broken.
The conventional sensor loop used for protecting the conveyor belt against longitudinal continuous cut suffers also from the following two main drawbacks: -
(a) the two free ends of the steel cord forming the loop
being joined together by soldering or brazing makes the joint
relatively hard and brittle, and therefore liable to be broken by
flexing of the conveyor belt during performing the conveying
operations; and
(b) the four corners of the rectangular shaped sensor loop
formed by sharp bends of the steel cord are relatively fragile and
therefore broken by the flexing of the conveyor belt during
performing the conveying operations.
The object of the prevent invention is to provide an improved sensor loop for preventing longitudinal continuous cut in rubber conveyor belts, in which the said drawbacks of the conventional sensor loop are removed to a large extent, if not completely.
The improved sensor loop according to the invention is of substantially rectangular configuration and comprises a pair of endless loops placed one inside the other with a predetermined gap left between the adjacent sides thereof and produced from steel ropes, which are pre-bent in a zig-zag/wavy pattern, the two free ends of each said steel rope forming an endless loop being joined by braiding the strands thereof, instead of soldering or brazing the
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free ends as is done in the conventional sensor loop.
Thus the invention provides an improved sensor loop for detecting and arresting longitudinal continuous cut in rubber conveyor belts, being embedded in the rubber cover of the conveyor belts, and operable as a part of an electronic control system, such as herein described, characterised in that the sensor loop comprises a pair of separate endless loops of substantially rectangular configuration, each endless loop being made of a steel rope which is pre-bent in a zig-zag/wavy pattern, and that the two free ends of the steel rope forming an endless loop are Joined by braiding strands thereof.
The invention provides a method of constructing an improved sensor loop for detecting and arresting longitudinal continuous cut in rubber conveyor belts, comprising (a) bending a steel rope in a zig-zag/wavy pattern, (b) forming a loop with the rope of substantially rectangular configuration, (c) unbraiding the two free ends of the rope into two separate strands at each free end, (d) cutting off one of two strands at each free end, (e) braiding the two strands left one at each free end, (f) zinc coating and rubberising the endless loop formed, and (g) selecting two endless loops, one being of bigger dimensions than the other, to form the improved sensor loop.
The invention is described fully and particularly, in an unrestricted manner, v/ith reference to the accompanying drawings of the provisional specification and the complete specification, in which -
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Figure 1 is a schematic view of one embodiment of the improved sensor loop embedded in the rubber cover of a rubber conveyor belt with the longitudinal sides of the sensor loop lying along the width of the conveyor belt;
Figure 2 is a schematic layout of the electronic control system used with the sensor loop for detecting and arresting longitudinal continuous cut in a rubber conveyor belt; and
Figure 3-illustrates a method of joining the two free ends of a pre-bent steel cord forming an endless loop.
Referring to Figure 1, the invented sensor loop comprises a pair of endless loops (1, 2), disposed one inside the other, each loop (1, 2) being made of a steel rope prebent along the length thereof in a zig-zag pattern.
In a particular embodiment of the invented sensor loop, embedded in conveyor belt (5), the outer loop (1) is of length 1700 mm and breadth 320 ram, the inner loop (2) is of length 1650 mm and breadth 280 mm, the gap (3) between the outer (1) and inner (2) loops is 25 mm, the sides (4) of each zig-zag part of steel rope are of length 50 mm, the steel rope used is of diameter 1.7 mm and the two free ends of the steel rope are joined by splicing over a length of 300 mm for each loop (1, 2).
The loops are embedded in a horizontal plane with their longitudinal sides lying along the width of a conveyor belt (5) of breadth 1750 mm and thickness 4.25 nan.
Referring to Figure 3, Figure 3(A) shows the two free ends (a and b) of steel rope (1') forming an endless loop (1) of the improved sensor loop; Figure 3(B) shows unbraided strands
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(a' and a") at one free end (a), and unbraided strands (b' and b") at the other free end (b) of steel rope (1'); and Figure 3(C) shows the joint (C) formed by first cutting off the strands (a' and b"), and braiding the remaining strands (a" and b') at the free ends (a and b) respectively of steel cord (1').
The joint (C) thus formed by braiding the strands of the two free ends of a steel cord and without soldering or brazing of the free ends of the steel cord is flexible, and hence is not liable to be ruptured by flexing of the conveyor belt during performing the
conveying operations.
After constructing an endless loop by joining the free ends of a steel cord in the method described with reference to Figure 3, the loop is zinc coated and rubberised to ensure adequate bonding of the loop with the rubber cover of conveyor belts, in which the sensor loop is embedded.
Referring to Figure 2, the electronic control system used for preventing longitudinal continuous cut in a conveyor belt (5) using the improved sensor loop comprises a chute (6) for feeding the materials to be conveyed at a region (7) of the conveying path which is identified to be a vulnerable region to cause longitudinal cut in the belt; a first pair of transmitter (8) and receiver (9) for transmitting an electromagnetic signal from transmitter (8) to receiver (9) via the sensor loop (10) embedded in the conveyor belt (5) when sensor loop (10) is moved to the location of the transmitter and receiver pair (8,9), disposed underneath the conveyor belt (5) at the left-hand side of said vulnerable region (7); a driven drum (11) for driving the conveyor belt (5) in the direction of arrows (12 and 13);a second set of transmitter (14) and receiver
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(15), disposed underneath the conveyor belt at the right-hand side of said vulnerable region (7), for transmitting an electromagnetic signal from transmitter (14) to receiver (15) via the sensor loop (10) when the sensor loop (10) is moved to a position near the pair of transmitter (14) and receiver (15) by the conveyor belt driven by drum (11) in the direction (12); a non-driven drum (16) fitted with a plurality of pulse signal emitting source (17) along the periphery thereof emitting pulse signals of strength relative to the distance of a sensing loop therefrom; a proximity switch (18) positioned adacent to the non-driven drum (16) for picking up the pulse signals from sources (17); a processor unit (19) for processing the signal inputted into it from each of said transmitters (8, 14), receivers (9, 15) and proximity switch (18) and thereby detecting the occurrence of a rupture of the sensing loop and stopping further movement of the conveyor belt (5) by disabling the driven drum (11) by operating switch (21), and stopping further flow of materials in chute (6) by operating key (20). In this way the occurrence of a continuous cut ia the conveyor belt is prevented by the system shown in Figure 2.
The performance of the system shown in Figure 2 by embedding the invented sensor loop in the conveyor belt (5) has evaluated in the mining environments, above and underneath the ground surface, and compared against the average performance of the corresponding system operated by embedding a conventional sensor loop in the conveyor belt. The following advantages have been obtained by using the invented sensor loop :-
(i) the length of longitudinal cut in the conveyor belt is reduced appreciably;
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(ii) the frequency of unnecessary stoppage of the conveyor belt during its production run arising from breakage of the steel rope forming the sensor loop by flexing of the conveyor belt even when there is no longitudinal cut in the conveyor belt, is almost totally eliminated;
(iii) the efficiency of conveyor belt performance is increase significantly; and
(iv) the maintenance cost of the conveyor belt is reduced drastically.
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We claim :-
1. An improved sensor loop for detecting and arresting
longitudinal continuous cut in steel cord reinforced rubber conveyor
belts, being embedded in the rubber cover of the conveyor belts,
and operable as a part of an electronic control system, such as
herein described, characterized in that the sensor loop comprises a
pair of separate endless loop (1, 2) of substantially rectangular
configuration, each endless loop being made of a steel rope (1')
which is pre-bent in a zig-zag/wavy pattern, and that the two free
ends (a, b) of the steel rope (1') forming an endless loop are
joined by braiding strands (a", b') thereof.
2. The improved sensor loop as claimed in claim 1,
wherein the braided strands are each of length 300 mm.
3. The improved sensor loop as claimed in claims 1 and 2,
wherein each endless loop is zinc coated and rubberised.
4. An improved sensor loop for detecting and arresting longitudinal continuous cut in rubber conveyor belts, substantially as herein described.
5. A method of constructing an improved sensor loop for detecting and arresting longitudinal continuous cut in steel cord reinforced rubber conveyor belts as claimed in any one of the preceding claims, comprising (a) bending a steel rope in a zigzag/wavy pattern;(b) forming an endless loop, using the rope, of substantially rectangular configuration; (c) unbraiding the two free ends of the rope into two separate strands at each free end; (d) cutting off one of the two strands at each free end; (e) braiding the two strands left one at each free end; (f) zinc coating and
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rubberising the endless loop formed; and (g) selecting two endless loops, one being of bigger dimensions than the other, to form the improved sensor loop.
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6. A method of constructing a sensor loop for detecting
and arresting longitudinal continuous cut in steel cord reinforced
rubber conveyor belts, substantially as herein described.
7. A method of embedding the sensor loop for detecting
and arresting longitudinal continuous cut in steel cord reinforced
rubber conveyor belts as claimed in any one of the preceeding
claims, comprising embedding a pair of endless loops of different
dimensions, with the longitudinal sides thereof lying along the
width of the conveyor belts so as to cover substantially the entire
width of the belts, the endless loop of smaller dimensions being
placed inside the endless loop of bigger dimensions leaving a pre
determined gap between the adjacent sides of the said two endless
loops, at required intervals along the length of the conveyor belts.

An improved sensor loop for detecting and arresting longitudinal continuous cut in rubber conveyor belts, being embedded in the rubber cover of the conveyor belts, and operable as a part of an electronic control system, such as herein described, characterised in that the sensor loop comprises a pair of separate endless loops (1, 2) of substantially rectangular configuration, each endless loop being made of a steel rope (1') which is pre-bent in a zig-zag/wavy pattern, and that the two ends (a, b) of the steel rope (1') forming an endless loop are joined by braiding strands (a", b') thereof.

Documents:


Patent Number 209244
Indian Patent Application Number 00687/CAL/2002
PG Journal Number 34/2007
Publication Date 24-Aug-2007
Grant Date 23-Aug-2007
Date of Filing 10-Dec-2002
Name of Patentee PHOENIX YULE LIMITED
Applicant Address "IDEAL PLAZA", 11/1, SARAT BOSE ROAD, KOLKATA-700 020.
Inventors:
# Inventor's Name Inventor's Address
1 WOLFGANG SCHNELL PHOENIX CONVEYOR BELT SYSTEM GMBH, PHOENIX CBS GMBH, HANNOVER STRASSE 88, 21079 HAMBURG,
2 TIMIR BARAN BHATTACHARJEE PHOENIX YULE LTD., P.O.GAYESHPUR, KALYANI, DIST. NADIA, PIN-741 234.
PCT International Classification Number B 65 G 43/02
PCT International Application Number N/A
PCT International Filing date
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 NA