HRP921274A2 - Electrical conductor - Google Patents

Description

Background of the invention

The invention relates to conveyor belts in which electrical conductors, sensors, antenna frame, etc. should be installed, as well as systems using such belts. In particular, the present invention relates to an improved guide, antenna frame, sensors, etc. that can be used in such bands.

Generally, an electrical conductor, such as a wire, is formed in the form of a closed circuit, such as a node, and is embedded in an elastomeric conveyor belt. Brass-clad high-strength steel wires and copper ropes (as described in English Patent 1,384,499) are used for this purpose. The strip may have one or more conductors extending transversely across the width of the strip spaced apart along the length of the strip. These conductors are mostly in an unexcited state, i.e., without current flow until they pass in front of the detector, in the form of a coil that induces a current flow in the compliant node. The detection system is used to control or detect the induced current flow in the conductive loop. This information can be used to control the movement of the tape, as an indication of the position of the tape, or it can be used to indicate the occurrence of tearing or tearing of parts of the tape.

It is common knowledge that heavy duty conveyor belts are susceptible to tearing or splitting along their length. If the belt is not stopped within a short period of time after a portion of the belt tear occurs, the belt tear continues for a very long length of the belt causing extensive damage to the belt and major repairs to the belt and/or conveyor system. By stopping the belt quickly, damage can be minimized, thus reducing costs and downtime of the belt during repairs. therefore, it is important that the integrity of the detection system is maintained at a high level. However, over time, one or more guides may fail.

The guide can cancel for various reasons. The guide in the belt is continuously bent during the operation of the belt. This causes changes in the direction of the belt, the support rollers as well as the load itself, which is placed on the belts, transferred and unloaded. This continuous buckling, bending, stretching, compression, etc. leads to the eventual failure of the conductor due to fatigue of the material.

Another cause of failure lies in the surrounding environment. The conveyor belt can be subjected to various environmental changes. Water, for example, either in a liquid or vapor state can come into contact with the conductor. The linings of the support rollers on which the tape rests can be the cause of the appearance of porosity and/or the development of fine cracks or fissures during operation, which allows the penetration of moisture. Water that penetrates to the conductor can corrode it, thus weakening it at the cross-section and possibly breaking it. To make the problem more complex, it should be pointed out that many strips were used in areas of environments where acidic conditions prevail (low pH). Because of this, the moisture that penetrates through the tape to the conductor can be acidic in nature. This increases the likelihood that the conductor will corrode and eventually fail.

If damage appears on the tape, it will spread until one of the conductors breaks. The detector system will then detect a broken conductor and stop the tape. However, if the guide fails, as described in the previous text, the detector system will stop the conveyor, not distinguishing the malfunction from actual belt damage. In order for the drive to continue, the guide must be replaced, if possible, or the detection system must be adjusted so that it does not control the lane zone in which the broken guide is located, or the entire detection system must be turned off. The last two operations result in reduced or no tape protection in places where damage can occur by tearing parts of the tape causing much damage before the defect is detected.

Description of the drawing

The text below represents a brief description of the drawing:

Fig. 1. shows a simplified perspective view of the conveyor belt damage detection system;

Sl. 2 shows a partial and enlarged view of an electrical conductor according to one aspect of the invention;

Sl. 3 shows a partial view of the strip 52 in which the electrical conductor of FIG. 3 of one type of configuration is located;

Sl. 4 shows a cross-sectional view of a conductor according to one embodiment of the present invention;

Sl. 5 shows a cross-sectional view of the second conductor according to another embodiment of the present invention;

Sl. 6 shows, in part, the method of installing the guide during the manufacture of the tape.

Description of the invention

According to one aspect of the present invention, a conveyor belt is provided which has a corrosion resistant metal conductor, sensor, frame antenna, etc. embedded in the belt to form a closed current junction. According to another aspect of the invention, the conductor has a conductive core of a first metal and an outer sheath of solid fibers and/or ropes of a second metal. The conductive core is made of metals with good conductive characteristics such as copper, brass, aluminum, etc.

The conductor will be subjected to frequent bending and twisting during operation, and therefore must have good fatigue resistance, the ability to resist weakening or damage from these repeated cycles. However, the characteristics of high fatigue resistance and high conductivity (low electrical resistance) are generally mutually exclusive.

Because of this, the conductor further comprises a greater number of solid fibers and/or ropes that have a higher resistance to fatigue than the conductive core. These solid fibers and/or ropes are wrapped around the conductive core to increase the resistance of the conductive core to fatigue and bending, twisting, etc., which occur during conveyor belt operation. It is further recommended that these outer solid fibers be corrosion resistant in order to extended the life of conductors in corrosive environments as already explained.

According to a further aspect of the present invention, the solid fibers should be selected to be elastically conductive. Because the conductive core generally has poor fatigue characteristics, it will eventually experience surface cracks. these cracks can deepen until the conductive core is completely broken. If, however, the outer solid conductors have any conductivity they will be able to bridge the breaks, allowing current to continue to flow through the conductor. This will increase the electrical resistance of the conductive core, but will allow the conductor to continue to operate until the number and resulting crack width increase the resistance to a level where they become inoperative for their intended role. As the resistance of the conductor increases and the number of cracks increases, the devices will be able to determine which conductor needs to be replaced before it fails completely. This can allow control devices to determine whether the guide has failed due to internal causes such as fatigue or external causes such as the occurrence of a section of ribbon tearing. The latter occurrence should cause the system to shut down, while the former occurrence should require the system to bridge the conductor or frame to the antenna and keep the system operating.

One conductor that could be made according to the present invention would comprise a plurality of stainless steel wires wrapped around a stainless steel core. However, this would lead to a conductor having a large overall outer diameter.

One conductor, which is made according to the present invention, contains a number of stainless steel wires as a solid conductor, wrapped around a copper core, forming a rope or cable. Stainless steel has good fatigue resistance and is resistant to corrosion while having a slightly lower electrical conductivity. The copper core can be a single solid wire or a certain number of individual copper wires twisted together to form a copper rope. As used herein, the term "wire" or "fiber" refers to a single parallel wire, and the term "rope" to a group of wires twisted, braided, or run in parallel to form a unit. The term cable refers to a structure comprising two or more ropes, or a combination of at least one rope with at least one wire.

The electrical conductor is embedded in a conveyor belt having an elastomeric body with a load-receiving surface or liner, as well as a parallel surface abutting the bearing rollers or liner with a reinforced layer placed on the elastomeric body. The electrical conductor can be installed either in the layer that carries the load, or in the layer that rests on the rollers, it can be placed between the reinforced layers or between the reinforced layer and any covering - load-bearing or adjacent.

The electrical conductor can be extended along the direction of movement of the tape or one or more conductors can extend transversely to the width of the tape, whereby the conductors are arranged in relation to each other at a distance along the length of the tape, i.e. the direction of movement. Electrical conductors are placed inside the strip along predetermined tracks. This can include paths in the form of nodes, rectangles, ovals, polygons, figures of eight, etc.

To facilitate bending, twisting and stretching, the conductor may be shaped to have a continuously repeating sinusoidal waveform within the strip. Although a sine waveform can have a three-dimensional shape, i.e. be aligned or in one plane only. Instead of a repeating sine wave, the conductor may be shaped according to any other wave pattern, such as a rectangular waveform, a sawtooth waveform, etc. The conductor, thus shaped, is placed in predetermined paths as already described (rectangle, ellipse, eight etc.). The tape with the built-in guide can then be introduced into or added to the positioning system, as well as/or into the detection system.

The present invention provides tapes and/or systems that contain guides that can bend or twist together with the tape during conveyor operation. In addition, the invention foresees conductors that are resistant to corrosive environments in some facilities, such as in mining. In this case, the invention overlooks a tape or system, which has an extended operating life and improved electrical and/or magnetic integrity of the conductor, requiring less interruptions for repairs and providing increased safety.

The improved electrical conductor can be used not only in new strip constructions, but is also suitable as a replacement for existing conductors that have been damaged and/or become inoperable in operation.

In addition, the conductor described has a relatively small diameter or cross-section, which makes it advantageous for use with tapes that have a relatively small thickness. the smaller thickness of the conductor allows it to be installed in the layer of tape that rests on the support rollers whose thickness is, for example, 6 mm or less.

The invention can be used with any type of reinforced elastomeric tape. This includes tapes with textile reinforcement as well as tapes with rope reinforcement. However, belt edge damage detection systems are typically used with rope-reinforced belts, due to the high cost of replacement and their use in critical applications. In addition, belts with reinforced ropes are subject to long longitudinal wear when damage occurs in the form of belt tearing or edge cracking.

With reference to Fig. 1, a tape damage detection system 10 is shown. The elastomer conveyor belt, known as an endless conveyor belt, rests on a number of rollers 14 (of which only the two end ones are shown) which carry the belt 12 and ensure its movement. The motor 16 provides the driving force for turning one end support roller 14 which drives the belt 12 in the direction indicated by the arrow 18. It is understood that the motor can also drive the belt in the opposite direction.

In the strip 12, a large number of conductors 20 are installed, in the form of antenna frames, sensors, etc. in the elastomeric layer 22, precisely in the direction of movement (arrow 18). The conductors 20 are shown in a simplified schematic form and are placed in tracks in the shape of the letter eight (eights). The guide can be used with a tape edge damage detection system that applies magnetic or electric fields, depending on the type of detection system used. The conductors 20 in such a system are generally used to generate current flow in the nodes when they are subjected to an electric or magnetic field. The damage to the edge of the tape will possibly extend until one of the conductors 20 is broken. A break in a conductor causes an interruption in current flow that interrupts the electromagnetic field that creates the circuit. Two coils or detectors 24, transmitter-receiver type, are coupled to the conductor 20 and can detect the cessation of the electromagnetic field, i.e. damage to the tape. The detector 24 provides a signal that controls an electronic circuit 26 that processes the signal and forms a signal that indicates tape damage. The damage signal can activate an alarm, audible and/or visual, whereby the operator can manually stop the belt conveyor and/or can produce a command signal 28 that is fed to the motor control block 30 for automatically shutting down the motor 16, thereby stopping the belt 12 transporter. Various detection systems have been used to control conductor breaks 20. For example known is the Tape Damage Detector described by the U.S. Patent No. 3,742,477, then a security control device, which is described in U.S. Pat. Patent No. 3,831,161 and a method and apparatus for extending the operating range of a condition control system, which is described in U.S. Pat. Patent No. 4,017,826, which assumes three examples which are incorporated herein by reference. It is understood that the guide described here can be used on other various detection systems. For example detector 24 can detect a change in resistance, magnetic flux, capacitance, or electrostatic field as well as electromagnetic field through strip 12.

Electronic control circuit 26 may monitor the signal received from detector 24 to determine which conductors or antenna frame 20 have begun to fail due to wear. If the signal from each conductor 20, i.e. the antenna frame, is written into the memory when the tape 12 is new or when a new conductor 20 is installed, the electronic control circuit 26 can perform a comparison of the received signal from a place on the tape and the original signal written in the memory. Over time the received signal will decrease as more and more of the stainless steel wire carrying the highly conductive core of the conductor will take over the role of signal generation, indicating that the conductor 12 has begun to fail at that location. The electronic control circuit 26 can produce a signal at some predetermined allowable value, which will indicate the potential failure of a particular conductor 20. By determining the potential failure of a conductor, the control circuit 26 can automatically bypass that conductor and leave it out of control, if desired to prevent unnecessary tape stop caused by internal damage to the conductor 20 and not by a tape defect.

The guide 20 can extend completely over the entire width of the strip 12 so that it reaches the very edge of the strip or it can be away from the edge depending on the type of detection system and the specific requirements.

Fig. 2 shows an enlarged partial view of one way of making an electrical conductor. The conductor 40 consists of a number of stainless steel wires 42 wrapped around a copper core. The conductor 40 is shaped in the form of a sinusoid in the plane. Although the period "T" of the sinusoid can be varied depending on the application, the conductors 40 are made so that the repetition period has a length of about 19 to 22 mm, with an amplitude-to-amplitude bandwidth A of about 8 mm to about 10 mm. The sinusoidal conductor is then shaped into various track shapes.

The conductor 20 or 40 can be wound so that it has a figure eight shape, as shown in Fig. 1 or some other shape. Fig. 3 shows another way of performing the shape of the node where the conductor 50 is curved sinusoidally and formed into a rectangular node and embedded in the belt 52 of the conveyor.

Figures 3 and 4 show a cross-section of two different conductors made according to one of the objectives of the present invention. Each conductor has a core of solid copper wire around which a number of stainless steel wires are wrapped or twisted. In each conductor, a greater number of cladding wires are in line contact with the copper core. This allows the stainless steel wires to carry part of the electrical signal ie current. This is particularly important in the event that the copper wire begins to eventually develop cracks as already explained and with this the failure process begins, the stainless steel wires provide the current paths to bridge these cracks and maintain the electrical integrity of the conductor. The conductors in Fig. 4 and 5 represent two types of conductors that can be produced according to the present invention. It should be emphasized that the example of each wire and the number of wires may vary depending on the tape, environmental conditions and the type of detection system used.

In Fig. 4, the copper core 60 is wrapped with a certain number of parallel stainless steel wires 62 placed closely together, with which the core 60 is in line contact. Each wire 62 is wrapped in the same direction. The copper core can have a diameter in the range of 0.01 mm to 0.15 mm, preferably in the range of 0.02 mm to 0.003 mm. The individual stainless steel wires 62 may have a diameter in the range of 0.02 mm to 0.08 mm with a preferred range of 0.02 mm to 0.025 mm.

In Fig. 5 the conductor has two layers of stainless steel wires wrapped around a copper core 82. The first or inner layer 82 of stainless steel wires 84 may be stacked or twisted in one direction while the second or outer layer 86 of stainless steel wires 88 may be stacked or twisted in the opposite direction to the inner layer 82.

As used herein, the direction of twist, lay, or helicity refers to the direction of twisting of the spirals of ropes or wires when held in a vertical direction. "Pitch length" or "pitch" is the axial length of helically wound wire required for the wire to make a 360° turn. The copper core in this case may have a diameter of about 0.07 mm to 0.15 mm with a preferred circumference of 0.035 mm to about 0.05 mm. The stainless steel wires 84 and 88 may have a diameter of about 0.02 mm to about 0.08 mm with a preferred girth of 0.02 to about 0.025 mm.

The helical shape is achieved by a number of stainless steel wires having a pitch length in the range of about 4 mm to 8 mm with a preferred range of 5 to 7 mm. The electrical resistance of each conductor should be less than 0.03 ohms per cm of length with a preferred range of 0.008 to 0.025 ohms per cm of length and less.

The guide can be embedded in the tape in several ways. Referring, for example, to Fig. 6, the construction of one non-vulcanized strip 90 can be seen. The strip 90 has an elastomeric system that forms a supporting layer 92 and an abutting layer 94 that is introduced into the compactor 96. Between the two layers 92 and 94, a rope 98 is inserted for reinforcement. strips 90. Each layer 92 and 94 has a layer of insulating adhesive 100 applied to the surfaces of the layers which are pressed against each other or against the rope. The conductive assembly 102 has an insulating layer 104, which may also be an adhesive, which electrically isolates the conductor from the rope 98 and secures it thereto. The textile layer 106 is placed between the insulating layer 104 and the conductor 108. The assembly of the tape is achieved by compression using a compactor 96 and then it is introduced into the press and finally vulcanized. The electrical conductor can also be installed in the field on site which is a constant practice. This normally involves cutting out the tire with the faulty guide and replacing it with a new one. The cut piece of rubber is then replaced with non-vulcanized rubber and then the area being repaired is treated with a mobile vulcanizing device.

Another way of installing the circuit that is described in V.S. Patent No. 4,621,727 as a conveyor belt damage sensor is provided herein for reference only. Although some representative embodiments and details are shown herein by way of illustration of the invention only, it is clear that various modifications and changes may be made by those skilled in the art without departing from the scope of the invention.

Claims (26)

1. An endless conveyor belt with a certain direction of movement, indicated by the fact that it has: a) elastomeric body that has a bearing layer and a layer parallel to it that rests on the support rollers; b) tape reinforcement layer placed inside the elastomeric body; and c) a conductor, placed inside the strip along a predetermined path, which forms a closed circuit; wherein said conductor has a greater number of solid fibers or ropes than the first metal, wrapped around the conductive core of the second metal, and the solid conductors have a greater fatigue resistance of the material than the conductive body, in order to increase the fatigue resistance of the conductive body. 2. Tape according to claim 1, characterized in that the solid conductors are electrically conductive. 3. Tape according to claim 2, characterized in that the solid conductors are resistant to corrosion. 4. The strip according to claim 3, characterized in that the conductor has the shapes of a repeating waveform only in one plane along said path. 5. The tape according to claim 3, characterized by the fact that it has a larger number of conductors, each of which is placed inside the tape along a predetermined path and forms a closed circuit, while all conductors are placed at a distance from each other along the direction of movement of the tape. 6. Tape according to claim 5, characterized in that said guides are arranged in the tape straight to the direction of movement of said tape. 7. Tape according to claim 6, characterized in that said conductive core is made of copper and said solid fibers or ropes are made of stainless steel. 8. A strip according to claim 7, characterized in that each conductor is a repeating sine wave, formed in only one plane along said predetermined path. 9. Tape according to claim 7, characterized in that the copper core of each conductor is helically wrapped with a larger number of internal stainless steel wires, which are also wrapped with a larger number of external stainless steel wires. 10. Tape according to claim 7, characterized in that the copper core is helically wrapped with stainless steel wire. 11. Tape according to claim 3, characterized in that the reinforcing layer consists of at least one string with a large number of steel ropes. 12. Tape according to claim 3, characterized in that said reinforcing layer has at least one textile layer. 13. Tape according to claim 1, characterized in that said conductor is embedded in a layer that rests on the support rollers. 14. Tape according to claim 1, characterized in that said conductor is installed between said reinforcing layer and said bottom layer that rests on the support rollers. 15. Tape according to claim 1, characterized in that said reinforcing layer has at least two reinforcing sub-layers and wherein said conductor is embedded between two reinforcing sub-layers. 16. Conveyor belt located within the belt damage detection system, which represents an endless conveyor belt with an elastomeric body that has a bearing layer for the load and a layer parallel to it that abuts the support rollers, then a reinforcement layer placed between the said bearing and abutting layer of the body of the tape, as well as a large number of conductors embedded inside the body of the tape, wherein said conductors represent closed circuits, then a means for moving said tape in a given direction, detector means arranged at predetermined intervals from said tape intended to control the continuity of said conductors, as well as control means that respond to the output signals from the detector and form a signal indicating a break in the continuity of at least one conductor, characterized in that said conductor has: a plurality of stainless steel wires wrapped around a copper body, wherein it is performed in the form of a repeated sine wave in one plane ; what each guide is; placed inside the lane on a predetermined track that extends transversely to the lane's direction of travel. 17. Guide according to claim 16, characterized in that the diameter of the guide is less than 1.0 mm. 18. Conductor according to claim 16, characterized in that the electrical resistance of the conductor is less than or equal to 0.065 ohms/cm. 19. Conductor according to claim 16, characterized in that the copper core consists of one solid wire. 20. Conductor according to claim 16, characterized in that the copper core consists of a large number of longitudinal copper wires. 21. Tape according to claim 16, characterized by the greater number of stainless steel wires of the inner and outer layers, wherein the wires of the inner layer of stainless steel are guided on the surface of the copper core, and the wires of the outer layer of stainless steel are placed over the periphery of the inner layer stainless steel wires. 22. Tapes according to claim 16, characterized in that said control means provide an indication corresponding to said output signal for said wear detector of said conductor. 23. Tapes according to claim 22, characterized in that the control means include a means for memorizing the signal from the said conductor, as well as means for comparing the recorded signal with the received signal, and also means for automatically bridging the said conductor when the received signal reaches a predetermined level. 24. A system for detecting defects on a conveyor belt moving along a closed path, characterized by having detector means placed along the path of the belt movement, as well as an elastomeric conveyor belt having installed electrically conductive conductors or an antenna frame for conducting signals transversely through the belt for time of normal tape operating conditions and to interrupt the signal through them when the tape or conductor is damaged where the antenna frame is made of a number of wires made of stainless steel. 25. The system according to claim 24, characterized in that said stainless steel wires are wrapped around a conductive core. 26. The system according to claim 25, characterized in that said conductor or antenna frame has the shape of a repeated sine wave in a single plane.