CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of, and priority to, U.S. Provisional Application No. 63/294,206 filed on 28 December 2021.

The aforementioned application is incorporated by reference herein in its entirety, and is hereby expressly made a part of this specification.

TECHNICAL FIELD

The present disclosure relates to vulcanizing presses and, in particular, to vulcanizing presses for splicing together sections of steel cord reinforced conveyor belts and methods of operating such presses.

BACKGROUND

Vulcanizing presses for steel cord reinforced conveyor belts are widely used in the mining industry for forming continuous conveyor belts, e.g. for splicing different sections of conveyor belting together. The most common forms today utilize compound heating elements comprised of silicon, ceramic or resistance wire heating elements which may be fragile, and which may not provide uniform heat distribution to the conveyor belt surfaces.

Maintaining the appropriate curing conditions in a vulcanizing press for conveyor belts is crucial to ensure finished conveyor belts are strong and durable enough to withstand the load and stresses of the conveyor system, particularly in high-tension or high-impact applications. Curing conditions include the pressure, temperature, confinement geometry, and other factors.

Monitoring and maintaining the correct temperature and pressure at surfaces of the conveyor belt in a vulcanizing press is important for ensuring the quality and durability of the finished product. For example, too much pressure can cause the belt material to be squeezed too tightly, causing material distortion for structural weakening, while on the other hand, too little pressure can result in a weak bond that may fail under the weight and stresses of the conveyor system. Similarly, temperatures kept too low may prevent full curing, and excessively high temperatures (maintained over a long time) may lead to overcuring. While using a high-quality, consistent belt material may improve strength and durability, such improvements may not be sufficient and may require increased material costs.

Temperature in a vulcanizing press for conveyor belts may be monitored using thermocouples or other temperature sensors that are installed between the platen or press faces and the conveyor belt cover surfaces. If the temperature becomes too high, heating is turned off to avoid overcuring or other damage. In some cases, measuring and controlling temperature in such ways may be expensive (due to equipment procurement, maintenance, and replacement costs), labor intensive, and ad-hoc.

Pressure in vulcanizing presses is typically maintained using air, water, glycol, or oil-filled pressure bags that constrain the vulcanizing cavity during the vulcanization process. In some cases, such pressure bags may be prone to leakage and may require outboard pressure sources to function. Rupture of such bag can also represent an occupational hazard.

Improvement is desired.

SUMMARY

There are increasingly pressing calls for improved vulcanizing presses for conveyor belts due to pressures building up in the mining industry. Greater efficiencies are being demanded of mining operations to reduce climate impact and to aid in cost-effective procurement of raw materials for global economies transitioning to greater electrification, including heavy use of batteries, and to alternative industrial processes. A growing emphasis on societal impacts of mining has led to increased demand for lower waste and improved worker safety and welfare. Accordingly, there is now a great desire to provide a vulcanizing press that is lighter in weight, more rugged, easier to deploy, safer to operate, and is suitable to produce faster, more reliable and more uniform vulcanization to produce higher quality splices. It is desired that such improvements enhance the ability to rapidly manufacture steel cord conveyor belt splices in the field, e.g. on a mining site.

Various aspects described herein may provide for a vulcanizing press that is comprised of fewer assemblage components allowing for easier deployment and setup, that is lighter and therefore more portable, that is more rugged in overall construction, that that does not utilize pressure bags containing air or hydraulic fluid to provide for vulcanizing cavity pressurization thereby increasing reliability and operator safety, that provides for continuous pressure indication in each of its sections during the vulcanization cycle, that provides for the more uniform generation and distribution of heat to the belt surfaces, that provides for the eddy current heating of the steel cords internal to the conveyor belt carcass to thereby decrease overall vulcanization cycle time, that more accurately measures conveyor belt cover temperatures during the vulcanizing process without the use of thermocouples or the like, that more accurately measures the internal steel cord carcass temperature during the vulcanizing process without the use of thermocouples or the like, and/or that uses heating elements electrically energized at low voltage and high current to thereby increase reliability and operator safety.

In an aspect, the disclosure describes a method of operating a vulcanizing press for forming a conveyor belt. The method of operating also includes while the conveyor belt is being pressed between a pair of platens of the vulcanizing press, providing an electrical signal to circuitry connected to a conductive plate of the vulcanizing press that is capacitively coupled to a reference circuit via the conveyor belt; determining an indication of a capacitance of the conveyor belt based on a response of the circuitry to the electrical signal, and determining a cure state of the conveyor belt based on the indication.

In an aspect, the disclosure describes a vulcanizing press for forming a conveyor belt. The vulcanizing press also includes a pair of platens configured to receive the conveyor belt therebetween for pressing against the conveyor belt; a conductive plate capacitively coupled to a reference circuit via the conveyor belt while the conveyor belt is being pressed between the pair of platens; circuitry connected to the conductive plate to supply electrical power to the conductive plate, the circuitry being configured to: determine an indication of capacitance of the conveyor belt based on a response of the circuitry to an electrical signal supplied to the circuitry while the conveyor belt is being pressed between the pair of platens; and determine a cure state of the conveyor belt based on the indication.

In an aspect, the disclosure describes a method of operating a vulcanizing press for forming a conveyor belt. The method of operating also includes while the conveyor belt is being pressed between a pair of platens of the vulcanizing press, energizing a conductive plate in thermal communication with the conveyor belt to heat the conveyor belt by resistive heating of the conductive plate to cause press vulcanization (e.g. rubber vulcanization or other treatment of an elastomer by applying heat and pressure), and providing an electrical signal to circuitry connected to the conductive plate. The method of operating also includes determining an indication of resistance of the conductive plate based on a response of the circuitry to the electrical signal; and determining a temperature of the conveyor belt based on the indication. In an aspect, the disclosure describes a vulcanizing press for forming a conveyor belt. The vulcanizing press also includes a pair of platens configured to receive the conveyor belt therebetween for pressing against the conveyor belt; a conductive plate in thermal communication with the conveyor belt to heat the conveyor belt by resistive heating of the conductive plate; and circuitry connected to the conductive plate to supply electrical power to the conductive plate, the circuitry being configured to: energize the conductive plate while the conveyor belt is being pressed between the pair of platens to heat the conveyor belt to cause press vulcanization; determine an indication of resistance of the conductive plate based on a response of the circuitry to an electrical signal supplied to the circuitry while the conveyor belt is being pressed between the pair of platens; and determine a temperature of the conveyor belt based on the indication.

In an aspect, the disclosure describes a vulcanizing press for forming a conveyor belt. The vulcanizing press also includes a pair of platens configured to receive the conveyor belt between opposing non-flat surfaces of the pair of platens for pressing against the conveyor belt, the nonflat surfaces being shaped to deform into flat surfaces when the conveyor belt is pressed between the pair of platens at a predetermined clamping force; a clamp assembly for clamping the conveyor belt between the pair of platens at the predetermined clamping force, and a heater for heating the conveyor belt while the conveyor belt is clamped between the pair of platens at the predetermined clamping force to cause press vulcanization of the conveyer belt between the flat surfaces.

In an aspect, the disclosure describes a platen for a vulcanizing press for forming a conveyor belt by pressing the conveyor belt against the platen at a predetermined clamping force under heating. The platen also includes a non-flat surface for pressing against the conveyor belt and shaped to deform into a flat surface when the conveyor belt is pressed against the non-flat surface at the predetermined clamping force.

In an aspect, the disclosure describes a method of operating a vulcanizing press. The method of operating also includes receiving a conveyor belt between opposing non-flat surfaces of a pair of platens of the vulcanizing press; clamping the conveyor belt between the pair of platens to deform the non-flat surfaces into flat surfaces pressing against the conveyor belt, and heating the conveyor belt while the conveyor belt is clamped between the pair of platens to cause press vulcanization of the conveyer belt between the flat surfaces.

In an aspect, the disclosure describes a vulcanizing press for forming a conveyor belt. The vulcanizing press also includes a pair of platens configured to receive the conveyor belt therebetween for pressing against the conveyor belt; and a conductive plate in thermal communication with the conveyor belt to heat the conveyor belt by resistive heating of the conductive plate while the conveyor belt is being pressed between the pair of platens to heat the conveyor belt to cause press vulcanization, the conductive plate comprising a plurality of slits to form a meandering current path on the conductive plate to allow resistive heating by power supplied to the conductive plate at substantially above 1250 A.

In an aspect, the disclosure describes a non-transitory computer-readable medium having stored thereon machine interpretable (or processor executable) instructions which, when executed by a processor, cause the processor to perform one or more computer-implemented method(s) of operating a vulcanizing press for forming a conveyor belt.

In an embodiment, such a method includes, while the conveyor belt is being pressed between a pair of platens of the vulcanizing press, causing an electrical signal to be provided to circuitry connected to a conductive plate of the vulcanizing press that is capacitively coupled to a reference circuit via the conveyor belt; determining an indication of capacitance of the conveyor belt based on a response of the circuitry to the electrical signal, and determining a cure state of the conveyor belt based on the indication.

In an embodiment, such a method includes, while the conveyor belt is being pressed between a pair of platens of the vulcanizing press, energizing a conductive plate in thermal communication with the conveyor belt to heat the conveyor belt by resistive heating of the conductive plate to cause press vulcanization, and causing an electrical signal to be provided to circuitry connected to the conductive plate.

In an embodiment, such a method includes determining an indication of resistance of the conductive plate based on a response of the circuitry to the electrical signal; and determining a temperature of the conveyor belt based on the indication.

Embodiments can include combinations of the above features.

Further details of these and other aspects of the subject matter of this application will be apparent from the detailed description included below and the drawings.

DESCRIPTION OF THE DRAWINGS

Reference is now made to the accompanying drawings, in which:

FIG. 1A is a cross-sectional end view of a vulcanizing press, in accordance with an embodiment; FIG. IB is a top plan view of the vulcanizing press of FIG. 1A, in accordance with an embodiment;

FIG. 1C is a side cross-sectional view of the vulcanizing press of FIG. 1A, in accordance with an embodiment;

FIG. 2 is a cross-sectional end view of the vulcanizing press while engaged with a conveyor belt, in accordance with an embodiment;

FIG. 3A is a side view of an assembly of five press sections of a vulcanizing press, in accordance with an embodiment;

FIG. 3B is a top plan view the assembly of FIG. 3A, in accordance with an embodiment;

FIG. 4A is a side elevation view of conductive plates, in accordance with an embodiment;

FIG. 4B is a top plan view of the conductive plates, in accordance with an embodiment;

FIG. 5 is a side elevation view of a two-component platen, in accordance with an embodiment;

FIG. 6 is a schematic view of circuitry coupled to the plates, in accordance with an embodiment;

FIG. 7 is a plot of a characteristic cure curve, in accordance with an embodiment;

FIG. 8A is a plot showing variation of torque on a cure meter over time, in accordance with an embodiment;

FIG. 8B is a plot showing variation of pressure on a cure meter over time, in accordance with an embodiment;

FIG. 9A shows plots illustrating variation of material properties with cure time, in accordance with an embodiment;

FIG. 9B shows plots illustrating variation of permittivity with cure time, in accordance with an embodiment;

FIG. 9C shows plots illustrating variation of permittivity with stiffness, in accordance with an embodiment;

FIG. 10 is a flow chart of a method of operating a vulcanizing press for forming a conveyor belt, in accordance with an embodiment;

FIG. 11 is a flow chart of a method of operating a vulcanizing press for forming a conveyor belt, in accordance with an embodiment; FIG. 12 is a flow chart of a method of operating a vulcanizing press for forming a conveyor belt, in accordance with an embodiment; and

FIG. 13 illustrates a block diagram of a computing device, in accordance with an embodiment of the present application.

DETAILED DESCRIPTION

The following disclosure relates to a vulcanizing presses and methods of operating the same. In particularly, there are disclosed vulcanizing presses especially well-suited for the manufacture of steel cord conveyor belt splices or joints. In various embodiments, a vulcanizing press is provided that is comprised of fewer assemblage components allowing for easier deployment and setup, that is lighter and therefore more portable, that is more rugged in overall construction, that does not utilize pressure bags containing air or hydraulic fluid to provide for vulcanizing cavity pressurization thereby increasing reliability and operator safety, that provides for continuous pressure indication in each of its sections during the vulcanization cycle, that provides for the more uniform generation and distribution of heat to the belt surfaces, that provides for the eddy current heating of the steel cords internal to the conveyor belt carcass to thereby decrease overall vulcanization cycle time, that more accurately measures conveyor belt cover temperatures during the vulcanizing process without the use of thermocouples or the like, that more accurately measures the internal steel cord carcass temperature during the vulcanizing process without the use of thermocouples or the like, and/or that uses heating elements electrically energized at low voltage and high current to thereby increase reliability and operator safety.

Aspects of various embodiments are described in relation to the figures.

FIG. 1A is a cross-sectional end view of a vulcanizing press 10, in accordance with an embodiment.

FIG. IB is a top plan view of the vulcanizing press 10 of FIG. 1A, in accordance with an embodiment.

FIG. 1C is a side cross-sectional view of the vulcanizing press 10 of FIG. 1A, in accordance with an embodiment.

Referring to FIGS. 1A-1C, the vulcanizing press 10 comprises specifically one press section. A vulcanizing press may comprise more than one section depending on the longitudinal length of the conveyor belt to be formed and/or a splice thereof to be manufactured. A steel cord conveyor belt 12 is held within a vulcanization cavity created by edge bars 14A, 14B. This serves to transversely constrain the vulcanization of uncured rubber (not shown for clarity). Longitudinal constraint may be effected by the cured parent belt ends themselves. Vertical constraint may be effected by top plates 16A for heating as well as the bottom plates 16B for heating.

The plates 16A, 16B are in thermal contact or thermal communication with surfaces of the conveyor belt 12. For example, such thermal communication may be effected through an intermediate thin non-stick sheet (not shown for clarity). The plates 16A, 16B may be seen to be constrained vertically by an upper thermal insulating pad 18A and a lower thermal insulating pad 18B

The plates 16A, 16B may be sandwiched between upper and lower traverse bars defined by respective upper and lower platens 20A, 20B, which may be comprised of aluminum or the like. The pair of platens 20A, 20B are disposed on opposing sides of the conveyor belt 12 and are configured to receive the conveyor belt 12 between opposing non-flat surfaces 28A, 28B thereof for pressing against the conveyor belt 12. The plates 16A, 16B may be proximal to the conveyor belt 12 relative to the pair of platens 20A, 20B. The non-flat surfaces 28A, 28B may be arcuate surfaces extending between opposite ends of the pair of platens 20A, 20B to extend laterally across the conveyer belt 12.

A clamp assembly may clamp the conveyor belt 12 between the pair of platens 20A, 20B at a predetermined clamping force. The clamp assembly may include a first clamp 30A and second clamp 30B disposed at the opposite ends of the pair of platens 20A, 20B to clamp the pair of platens 20A, 20B against each other at the predetermined clamping force. Each of the first and second clamps 30A, 30B may be formed by a corresponding tie bolts 22A, 22B and tie nuts 24A, 24B that tie together the opposing ends of the platen 20A, 20B. Engagement of the tie bolts 22A, 22B with the tie nuts 24A, 24B may allow the non-flat surfaces 28A, 28B to be drawn towards each other.

The vulcanizing press 10 may have sensors 32A, 32B for generating data indicative of the clamping force. In some embodiments, the sensors 32A, 32B may be a pair of strain gauges mounted on the pair of platens 20A, 20B to generate data indicative of deformation of the pair of platens 20A, 20B. In some embodiments, the clamping assembly may be configured to cause varying of pressing of the platens 20A, 20B against the conveyor belt 12 in response to an input by the control system 34. For example, the clamping assembly may include an actuator for such purposes.

Upper fulcrum spacer bars 26A (at left and right ends of the vulcanizing press 10) rest or are disposed on top of edge bars 14A, 14B and which contact the a (bottom) surface of the platen 20A. Similarly, lower fulcrum spacer bars 26B (at left and right ends of the vulcanizing press 10) are disposed on the bottom of edge bars 14A, 14B and which contact a (top) surface of the platen 20B. The ends of the platens 20A, 20B may pivot on the fulcrum bars 26A, 26B. Synchronous tightening of tie nuts 24A, 24B may place the platens 20A, 20B under tension/compression and effect deformation thereof.

The plates 16A, 16B may form a heater for heating the conveyor belt 12 while the conveyor belt is clamped between the pair of platens 20A, 20B. The plates 16A, 16B may be conductive and configured to receive electrical power to heat the conveyor belt 12 by resistive heating of the plates 16A, 16B while the conveyor belt 12 is being pressed between the pair of platens 20A, 20B to heat the conveyor belt 12 during press vulcanization. The vulcanizing press 10 may include circuitry connected to the pair of conductive plates 16A, 16B to supply electrical power thereto. For example, the circuitry may be part of a control system 34. The control system 34 may be connected to a power supply (not shown for clarity). For example, a mine site may provide about 25 kW of power via each available electrical supply circuit to the power supply. The upper plate 16A has electrical connection studs 36A, and the lower plate 16B has electrical connection studs 36B.

In various embodiments, circuitry may include processor(s), computer-readable memory with instructions thereon, traces on printed circuit boards, user interfaces, and/or other analog or digital computing or circuit elements.

FIG. 2 is a cross-sectional end view of the vulcanizing press 10 while engaged with the conveyor belt, in accordance with an embodiment.

As shown in FIG. 2, the slight curved profile (shown exaggerated for clarity) of the non-flat surfaces 28A, 28B may be deformed under tension/compression as a varying force is applied at their ends. In particular, the non-flat surfaces 28A, 28B may be shaped to deform into flat surfaces shown in FIG. 2 when the conveyor belt 12 is pressed between the pair of platens 20A, 20B at a predetermined clamping force. Advantageously, pillowing or misshaping of the conveyer belt 12 (pulley and carry cover layers) may be avoided without the use of pressure bags or other form of distributed force applied across the platens 20A, 20B.

For example, if a platen is modelled as a beam clamped at both ends and assuming a load concentrated in the middle, the deflection may be defined as (3rd order equation):

Wx ¹ y ⁼ (3F — 4x) y 48EI ^{k 7} with a maximum deflection at load of

WL

192E1

For example, if a platen is modelled as a beam clamped at both ends with a uniformly distributed load q, the deflection at position x may be defined as (4th order equation):

The profiles of the non-flat surfaces 28A, 28B may be adapted so that their shapes compensate for such deflections, leading to effectively flat surfaces for engaging with the conveyor belt 12 under loading.

The sensors 32A, 32B may be used to aid operators/erectors of the vulcanizing press 10 to synchronously adjust an initial applied tension (when the splice vulcanization cavity contains uncured rubber) so as to achieve the desired flatness of surfaces of the platens 20A, 20B engaged with the conveyor belt 12. For example, the sensors 32A, 32B may be strain gauges that may be used to provide an indication of deformation of the platens 20A, 20B. Such a deformation may be associated with a clamping force. At a particular clamping force, it is understood that the non-flat surfaces 28A, 28B may be flattened due to pressure applied thereto by the conveyer belt 12 under clamping. The deformation may vary as the cure state of the conveyer belt 12 changes and as such the clamping force may be varied to maintain a desired flatness of the platens 20A, 20B.

In some embodiments, a determination of the predetermined clamping force (i.e. the desired deformation of the platens 20A, 20B) may be achieved by an optical instrument. The upper traverse bar and lower traverse bar may be equipped with respective two-sided optical reflectors. These may be precision mounted on one side of the traverse bar so as to change their angle of incidence reflection as the traverse bar deforms from its normal shape under tension. This may be accomplished via the fixed curvature shape of the surface of the reflector and its vertical displacement caused by traverse bar deformation under tension. To indicate the tension via the reflectors action, a battery powered tension display module (not shown for clarity) may be temporarily affixed to each end of traverse bars. This module may contain a low-power laser as a coherent pinpoint light source and an optical graticule that indicates the reflected laser beam from the reflectors. As alluded to previously, for a specific conveyor belt width (and the consequent location of the edge bars and fulcrum spacer bars), along with the belt thickness, there may be a concomitant initial tension that is to be applied synchronously to each traverse bar end. This may be easily ascertained by the laser beam deflection as seen on the optical graticule by each operator as they tighten down their respective tie nuts. Thereafter, if vulcanization cavity pressure is to be monitored during vulcanization, the modules may be left in situ and the reflected beams may indicate further traverse bar deformation due to the expansion of the rubber during curing/vulcanization and the pressure resulting therefrom. Precise control over the vulcanization pressure during rubber curing may be achieved without the need for pressure bags or the like.

The plates 16A, 16B may form a heater for heating the conveyor belt 12 while the conveyor belt is clamped between the pair of platens 20A, 20B at the predetermined clamping force to cause press vulcanization of the conveyer belt between the flat surfaces. The plates 16A, 16B may be energized by the control system 34 to heat the conveyor belt 12 by resistive heating so as to cause press vulcanization while the conveyor belt 12 is being pressed between the pair of platens 20A, 20B

The pair of plates 16A, 16B may be capacitively coupled to a reference circuit, e.g. to each other via the conveyor belt 12 and/or ground, while the conveyor belt 12 is being pressed between the pair of platens 20A, 20B since the rubber in the conveyor belt 12 may serve as dielectric disposed between the pair of plates 16A, 16B and between the pair of plates 16A, 16B and the ground. The control system 34 may determine this capacitance by providing a probe signal and using circuitry to measure this capacitance or an indicator of this capacitance. For example, a time constant associated with capacitor discharge may be used to estimate the capacitance. The capacitance (or an indicator thereof) can then be related to a cure state of the conveyor belt 12. This may be provided to a user through an interface and/or be used to control heating and pressing of the conveyor belt 12, e.g. heating may be stopped the conveyor belt 12 is fully cured. Advantageously, real-time or near real-time monitoring of the vulcanization process may be achieved. The resistivity of the plates 16A, 16B may be temperature dependent. Such a resistivity may be determined by control system 34 by using a probe signal and evaluating its response. The temperature of the plates 16A, 16B may then be determined based on the resistivity of the plates 16A, 16B. Such a temperature may be closely related to a temperature of the conveyor belt 12. For example, it may be used as a surrogate or may be used in calculations to determine the temperature of the conveyor belt 12 since the material properties between the plates 16A, 16B may be known. FIG. 3A is a side view of an assembly of five press sections of a vulcanizing press 110, in accordance with an embodiment.

FIG. 3B is a top plan view the assembly of FIG. 3A, in accordance with an embodiment.

The vulcanizing press 110 is an assemblage of five press sections 10A, 10B, 10C, 10D, 10E wherein there is shown upper cable 40 for electrical power delivery (only one is shown as will be made clearer later) and which is connected to a first upper heating plate via an electrical connection stud. For visual clarity, previously described individual parts of the press sections are not labelled. Also shown are a plurality of upper heating plate interconnect blocks and an upper interconnect loop cable connected to the last upper heating plate, via electrical connection studs. Also shown is lower cable 40 for electrical power delivery (additional cables for the same purposes may be provided but are not shown in FIGS. 3A-3B for visual clarity) and which is connected to a first lower heating plate via an electrical connection stud 36 (not numbered in FIGS. 3A-3B for visual clarity).

Also shown are a plurality of lower heating plate interconnect blocks 42 and a lower interconnect loop cable 40 connected to the last lower heating plate, via electrical connection studs 36. These electrical interconnect blocks 42 may serve to series connect the upper heating plates, and may also serve to series connect the lower heating plates.

As shown in FIG. 3B, the five leftmost upper heating plates are series connected along the left side of the press via interconnect blocks 42 between electrical connection studs 36. Upper loop interconnect cable 40 may connect the last leftmost upper heating plate to the last rightmost upper heating plate. Thereafter, as can be seen, the five rightmost upper heating plates may be series connected along the right side of the press via interconnect blocks 42. Accordingly, all ten of the upper heating plates may be electrically connected in series and then to an electrical power supply system. It should be noted that the cables 40 may be comprised of large gauge flexible copper stranded wire typically rated in the range of 500 A to 3000 A, e.g. similar to welding cables and the like. It should also be noted that the interconnect blocks 42 may likewise be comprised of copper for low resistance and serve not only electrically connect the heating plates in series, but may also serve to provide a large amount of longitudinal mechanical rigidity to the press assemblage as shown. For example, the interconnect blocks 42 may be substantially rigid to form substantially rigid interconnections between the press sections. Each interconnector block 42 may comprises two connectors to connect to two separate heating plates, e.g. the connectors may be or may include two receptacles.

FIG. 4A is a side elevation view of conductive plates 16, in accordance with an embodiment.

FIG. 4B is a top plan view of the conductive plates 16, in accordance with an embodiment.

For example, the assembly of plates 16 may be a heating plate similar to plates 16A, 16B and may define electrical connection studs 36 at its comers. The plates 16 may comprise two plates that at least span a width of the conveyor belt 12 and defined a gap 52 therebetween, e.g. each plate may have a length 48 of approximately half of a width of the conveyor belt 12. The plates 16 may be disposed adjacent to, and spaced apart from, each other. The plates 16 may be comprised of a sheet of suitable conductive material or metal having a high resistivity compared to copper, such as stainless steel or the like. Each plate may define a resistance less than 20 milliohms or about 10 milliohms.

Compared to conventional heating element configurations, the slitted plate construction may allow a greater choice of material for the plates 16. As such, advantageously, the plates 16 may, conveniently and cost-effectively, be made resistant to (unacceptable levels of) damage from corrosion, and be made to provide high strength under repeated cycling.

In each of the plates 16 there is a bolt relief and fulcrum spacer block recesses 50.

As shown in FIGS. 4A-4B, the conductive plates 16 (each) comprise a plurality of slits to form a meandering current path thereon (between electrical connection studs 36) to allow resistive heating by power supplied to the conductive plate at substantially above 1250 A. In some embodiments, the power may be supplied at a current of at least 700 A. In various embodiments, the power supplied to the conductive plate via the control system 34 may be supplied at substantially below 32 V, or below or about 20 V. For example, in some embodiments, power may be supplied at 1500 A and 32 V. Advantageously, such high currents and low voltages may enhance operational safety and, if suitably varied in time (e.g. by modulation), may create time-varying (pulsating) magnetic fields that lead to or cause substantial inductive or eddy current heating in conductive cords or cables embedded in a body of the conveyor belt 12. Advantageously, a more uniform heating of the conveyor belt 12 may be achieved.

Each slit of the plurality of slits may extend 90-95% between opposing ends its plate (see length 46). These transverse slits serve to increase the overall electrical resistance of the leftmost heating plate between its terminal electrical connection studs 36 and likewise between electrical connection studs 36 in the rightmost heating plate. To aid in stiffening the heating plate mechanically, the transverse slit widths may be kept small during manufacture and may be produced in the plate via laser or plasma or waterjet cutting or even precision punching. In various embodiments, the plurality of slits may then be backfdled with a suitable high strength, moderately flexible and high temperature insulating material, e.g. elastomeric epoxy. Such an insulating material disposed in the plurality of slits may be adhered to the plate therein. Advantageously, a desired low resistance may be achieved while maintaining high rigidity. It is found particularly advantageous that each slit of the plurality of slits open between 1 mm and 5 mm on its plate (see width 56).

A meandering path may be achieved by a first slit of the plurality of slits extending from a first end of a plate towards a second end thereof, and a second slit of the plurality of slits adjacent to the first slit extending from a second end of the plate towards the first end.

The thickness 54 of the plate is chosen such that between the length of the meandering electric current path effected by the transverse slits in the plate and the bulk resistivity of the metal chosen, the product is equal to the desired overall resistance of a singular heating plate. It is found particularly advantageous for the plates 16A, 16B to have a thickness 54 of less than 5 mm or between 1-5 mm.

The heating plate electrical connection studs 36 may also be comprised of copper and may be press fit into the heating plate according.

In various embodiments, the number of slits and/or the inter-slit distance (see width 58) may be varied for a given plate dimension to achieve a desired resistance, e.g. 10 milliohms.

FIG. 5 is a side elevation view of a two-component platen 120, in accordance with an embodiment. An arcuate plate 62 may define a non-flat surface 28. The arcuate plate 62 may be integrally coupled to a body 60 of a platen 120, e.g. by being held together by fasteners 64 such as rivets, nuts and bolts, welded/brazed joints, or via adhesive coupling (via an adhesive). The arcuate plate 62 may be removably coupled to the body 60. The arcuate plate 62 may be machined or otherwise manufactured separately from the body 60. Advantageously, this may reduce manufacturing costs and may allow changing of non-flat surfaces used in platens of the vulcanizing press, e.g. to accommodate a variety of conveyor belts.

FIG. 6 is a schematic view of circuitry coupled to the plates 16A, 16B, in accordance with an embodiment.

Multiple functions may be provided by the heating plates of the vulcanizing press and their interactions with the conveyor belt 12 undergoing vulcanization. There may be an upper heating control unit 70A typically supplied via three phase electrical line power as shown. The upper heating control unit 70A may comprise a high-frequency buck converter 71A connected to circuitry for DC rectification, e.g. by use of diodes, although AC output may also be possible in some applications. In some embodiments, the buck converter 71A may be modulatable via one or more processor(s) and/or computing elements, which may perform measurement and feedback functions in order to effect delivery of continuous DC or pulsating (modulated) DC at low voltage, e.g. 16V, but at high current, e.g. 1500A, in such a case able to deliver up to 24KW (or more) of heating power across a series connection of heating plates as previously described. The low voltage may contribute significantly to an increase in press operator safety. Further contributing to press operator safety may be the fact that there is galvanic isolation between the supply line power and the output of the control unit 70A.

The output of upper heating control unit 70A may be connected via electrical power delivery cables 73A to upper heater 74A. The control unit 70A may be able to determine the temperature of heater 74A by measuring the overall resistance RTC associated with the top cover heater 74A during a modulated off state of power delivery, e.g. by sensing an indication of the resistance. Such an indication may be a sensed current in response to supplied fixed voltage power, or a sensed voltage in response to supplied fixed current power. Thereby, there may be provided a correlated indication of top cover temperature of the conveyor belt 12 during the vulcanization process.

A lower heating control unit 70B may be substantially similar the upper heating control unit 70A. In some embodiments, the control units 70A, 70B may in communication with each other in order to effect a precise vulcanization cycle (communication means are not shown for clarity), e.g. to obtain improved estimates of temperatures of the conveyor belt 12.

The output of tower heating control unit 70B may be connected via electrical power delivery cables 73B to tower heater 74B. The tower heating control unit 70B may comprises a high-frequency buck converter 7 IB connected to circuitry for DC rectification. In like manner, the control unit 70B may be able to determine the temperature of the conveyor belt 12 by measuring the overall resistance RBC associated with the bottom cover (pulley cover) heater 74B during a modulated off state of power delivery, by sensing an indication of the resistance. Such an indication may be a sensed current in response to supplied fixed voltage power, or a sensed voltage in response to supplied fixed current power. Thereby, there may be provided a correlated indication of bottom cover temperature of the conveyor belt 12 during the vulcanization process.

The heaters 74A, 74B may serve to heat the vulcanizing splice cavity from the top and bottom cover surfaces of the conveyor belt 12, respectively.

The heating control units 70A, 70B may be configured to control power supplied to the plates 16A, 16B. In various embodiments, the heating control units 70A, 70B may be configured to controllably supply or generate pulsating DC outputs (or AC as the case may be) at a suitable frequency in order to cause energization of the plates 16A, 16B of the heaters 74A, 74B so as to produce an overall magnetic field 78. The overall magnetic field 78 may be viewed as a superposition of substantially identical time-varying magnetic fields 78A, 78B attributable to respective heaters 74A, 74B (and specific conductive elements thereof, and especially the conductive plates 16A, 16B). The time-varying magnetic fields 78A, 78B may be of a substantial magnitude due to the large current densities involved, which may be enabled by tow resistance of the conductive plates 16A, 16B. The time-varying magnetic fields 78A, 78B may induce eddy currents (e.g. surface eddy currents) in steel cords embedded in the conveyor belt carcass. Advantageously, the steel cords may then also directly provide heating to the inside of the vulcanizing splice cavity, thereby aiding the vulcanization process in the curing of rubber, and thereby reducing the overall vulcanization cycle time and increasing the quality of the cured splice.

By their operation, the control units 70A, 70B may have parasitic capacitances to ground 80 on its output, which may be determined or sensed, e.g. based on a model thereof. These parasitic capacitances further influenced by mutual capacitances between the upper heating system and the top surface of the internal steel cord carcass and the tower heating system and the bottom surface of the internal steel cord carcass. The steel cord bulk may be an electrostatic short circuit, so the determining factors may only be the overall capacitances in parallel as modified by the dielectric constant of the intervening rubber. The plates 16A, 16B may also be capacitively coupled to each other via the conveyer belt 12. Such parasitic capacitances may each separately, or altogether, may be viewed as a capacitance to one or more reference circuit(s). During output off cycles, the control units 70A, 70B may inject a high frequency probe voltage into the upper and lower heaters 74A, 74B surfaces respectively, and may then be configured to sense or measure an indication of such capacitance(s), e.g. capacitance relative to the ground.

As the uncured or partially cured rubber in the vulcanizing splice cavity cures, its dielectric properties may accordingly change. By determining the indication, changes in dielectric properties may be determined, estimated, or inferred. As such a cure state of the rubber/elastomer may be determined, e.g. a temperature of the rubber, a percentage of cure, a material property of the rubber, or a qualitative stage of curing, or other description of the cure state. For example, the control units 70A, 70B may then determine splice temperature spread between the heaters 74A, 74B and the internal steel cord carcass. The heaters 74A, 74B may adjust their respective heating contributions accordingly in order to effect even or efficient splice vulcanization.

The control units 70A, 70B may be part of the control system 34.

Parasitic capacitance may be determined using bridge(s) such as Wheatstone bridge(s), and/or by using digital means. For example, parasitic capacitance may be determined or modelled by measuring discharge time after provision of the probe signal (to determine a time constant associated with capacitance).

FIG. 7 is a plot of a characteristic cure curve 90, in accordance with an embodiment.

The cure measurement may be measured using a cure meter. For example, the cure measurement may be a stiffness, viscosity, or a torque as may be determined by a rotational rheometer, associated with vulcanization. In some embodiments, rotational rheometers may confine a soft matter or fluid between a cone and a plate.

In some embodiments, in a rotational rheometer, torque may be applied to oscillate a biconical disk embedded in a confined conveyor belt/rubber specimen and a heated square cavity exerts a sinusoidal shear strain on the specimen. The force (torque) needed to oscillate the disk is directly proportional to the stiffness (shear modulus) of the specimen. As the specimen cures, its modulus may increase (e.g. modulus of rigidity and/or Y oung’s modulus), and torque recorded as a function of time, which may yield the characteristic cure curve 90.

Point A of the curve 90 may be preheat, point B may be application of initial torque, point D may be application of minimum torque, point E may be scorch time, point F may be 90%, point G may be maximum torque, and point H may be overcure reversion. Point C may be structure.

FIG. 8A is a plot showing variation of torque on a cure meter over time, in accordance with an embodiment.

FIG. 8B is a plot showing variation of pressure on a cure meter over time, in accordance with an embodiment.

For example, such variations have been disclosed in, and reproduced here based on, Wang, X., Feng, N., & Chang, S. (2013). Effect of precured degrees on morphology, thermal, and mechanical properties of BR/SBR/NR foams. Polymer composites, 34(6), 849-859.

FIG. 9A shows plots illustrating variation of material properties (stiffness and speed of light) with cure time, in accordance with an embodiment.

FIG. 9B shows plots illustrating variation of permittivity with cure time, in accordance with an embodiment.

FIG. 9C shows plots illustrating variation of permittivity with stiffness, in accordance with an embodiment.

For example, such variations have been disclosed in, and reproduced here based on, Tayebi, S., Pourkazemi, A., Patino, N. O., Thibaut, K., Kamami, O., & Stiens, J. (2022). A Novel Approach to Non-Destructive Rubber Vulcanization Monitoring by the Transient Radar Method. Sensors, 22(13), 5010.

Permittivity may be proportional to, or otherwise dependent on, capacitance of the conveyor belt (rubber) as a dielectric material. The cure time may be a cure state or associated with a cure state.

Correlations such as those shown in FIGS. 8A-8B, and FIGS. 9A-9C may be used to determine a cure state based on sensed parasitic capacitance as described previously.

FIG. 10 is a flow chart of a method 1000 of operating a vulcanizing press for forming a conveyor belt, in accordance with an embodiment. Step 1002 of the method 1000 includes, while the conveyor belt is being pressed between a pair of platens of the vulcanizing press, providing an electrical signal to circuitry connected to a conductive plate of the vulcanizing press that is capacitively coupled to a reference circuit via the conveyor belt.

Step 1004 of the method 1000 includes determining an indication of a capacitance of the conveyor belt based on a response of the circuitry to the electrical signal.

Step 1006 of the method 1000 includes determining a cure state of the conveyor belt based on the indication.

In some embodiments of the method 1000, the reference circuit is a ground circuit. As referred to herein, a ground circuit may refer to a ground node or a circuit that is connected thereto. A ground node may define a reference potential. In various embodiments, ground node may refer to a signal ground, a power ground, a chassis ground, a floating ground, and/or earth ground.

In some embodiments of the method 1000, the conductive plate is a first conductive plate of a pair of conductive plates of the vulcanizing press that are capacitively coupled to each other via the conveyor belt, and the reference circuit is a circuit of a second conductive plate of the pair of conductive plates.

In some embodiments of the method 1000, the pair of platens are disposed on opposing sides of the conveyor belt to press the conveyor belt, each conductive plate of the pair of conductive plates being disposed on a corresponding side of the opposing sides of the conveyor belt so as to receive the conveyor belt between the pair of conductive plates.

Some embodiments of the method 1000 further comprise, while the conveyor belt is being pressed between the pair of platens, heating the conveyor belt by energizing the conductive plate for resistive heating of the conductive plate so as to cause press vulcanization.

Some embodiments of the method 1000 further comprise controlling power supplied to the conductive plate based on a determined cure state of the conveyor belt to control heat supplied to the conveyor belt during press vulcanization.

In some embodiments of the method 1000, the conductive plate may be proximal to the conveyor belt relative to the pair of platens.

In some embodiments of the method 1000, the indication is indicative of permittivity of a dielectric material forming the conveyor belt. Some embodiments of the method 1000 further comprise varying pressing of the pair of platens on the conveyor belt based on a determined cure state of the conveyor belt.

FIG. 11 is a flow chart of a method 1100 of operating a vulcanizing press for forming a conveyor belt, in accordance with an embodiment.

Step 1102 of the method 1100 includes, while the conveyor belt is being pressed between a pair of platens of the vulcanizing press, energizing a conductive plate in thermal communication with the conveyor belt to heat the conveyor belt by resistive heating of the conductive plate to cause press vulcanization.

Step 1104 of the method 1100 includes, while the conveyor belt is being pressed between a pair of platens of the vulcanizing press, providing an electrical signal to circuitry connected to the conductive plate.

Step 1106 of the method 1100 includes, determining an indication of resistance of the conductive plate based on a response of the circuitry to the electrical signal.

Step 1108 of the method 1100 includes, determining a temperature of the conveyor belt based on the indication.

In some embodiments of the method 1100, the pair of platens are disposed on opposing sides of the conveyor belt to press the conveyor belt, the conductive plate is one of a pair of conductive plates, each conductive plate of the pair of conductive plates being disposed on a corresponding side of the opposing sides of the conveyor belt so as to receive the conveyor belt between the pair of conductive plates.

Some embodiments of the method 1100 further comprise controlling power supplied to the conductive plate based on a determined temperature of the conveyor belt to control heat supplied to the conveyor belt during press vulcanization.

In some embodiments of the method 1100, the conductive plate is proximal to the conveyor belt relative to the pair of platens.

Some embodiments of the method 1100 further comprise varying pressing of the pair of platens on the conveyor belt based on a determined temperature of the conveyor belt. In various embodiments, varying pressing of the pair of platens may be achieved automatically in response to the determined temperature, e.g. by use of a motor coupled to the control system 34, since such a temperature may represent a cure state.

FIG. 12 is a flow chart of a method 1200 of operating a vulcanizing press for forming a conveyor belt, in accordance with an embodiment.

Step 1202 of the method 1200 includes receiving a conveyor belt between opposing non-flat surfaces of a pair of platens of the vulcanizing press.

Step 1204 of the method 1200 includes clamping the conveyor belt between the pair of platens to deform the non-flat surfaces into flat surfaces pressing against the conveyor belt.

Step 1206 of the method 1200 includes heating the conveyor belt while the conveyor belt is clamped between the pair of platens to cause press vulcanization of the conveyer belt between the flat surfaces.

In some embodiments of the method 1200, clamping the conveyor belt between the pair of platens includes using at least one sensor to generate data indicative of clamping force.

In some embodiments of the method 1200, the at least one sensor includes a pair of strain gauges mounted on the pair of platens to generate data indicative of deformation of the pair of platens.

FIG. 13 illustrates a block diagram of a computing device 1300, in accordance with an embodiment of the present application.

As an example, the method 1000, the method 1100, the method 1200, the control system 34, the control units 70A, 70B, and/or other device(s) described or shown herein may be implemented using the example computing device 1300 of FIG. 13.

The computing device 1300 includes at least one processor 1302, memory 1304, at least one I/O interface 1306, and at least one network communication interface 1308.

The processor 1302 may be a microprocessor or microcontroller, a digital signal processing (DSP) processor, an integrated circuit, a field programmable gate array (FPGA), a reconfigurable processor, a programmable read-only memory (PROM), or combinations thereof.

The memory 1304 may include a computer memory that is located either internally or externally such as, for example, random-access memory (RAM), read-only memory (ROM), compact disc read-only memory (CDROM), electro-optical memory, magneto-optical memory, erasable programmable read-only memory (EPROM), and electrically-erasable programmable read-only memory (EEPROM), Ferroelectric RAM (FRAM).

Non-transitory computer-readable medium may be provided, e.g. in the form of the memory 1304. The medium may have stored thereon machine interpretable instructions which, when executed by a processor, cause the processor to perform one or more computer-implemented method of operating a vulcanizing press for forming a conveyor belt. Such a medium may form a vendible product for facilitate retrofit of existing or conventional vulcanizing presses.

The I/O interface 1306 may enable the computing device 1300 to interconnect with one or more input devices, such as a keyboard, mouse, camera, touch screen and a microphone, or with one or more output devices such as a display screen and a speaker.

The networking interface 1308 may be configured to receive and transmit data sets representative of the machine learning models, for example, to a target data storage or data structures. The target data storage or data structure may, in some embodiments, reside on a computing device or system such as a mobile device.

The embodiments described in this document provide non-limiting examples of possible implementations of the present technology. Upon review of the present disclosure, a person of ordinary skill in the art will recognize that changes may be made to the embodiments described herein without departing from the scope of the present technology. For example, more than two platens may be used, the platens may be non-identical, and a single heating plate or more than two heating plates may be used to extend laterally across the conveyor belt for vulcanization. Yet further modifications could be implemented by a person of ordinary skill in the art in view of the present disclosure, which modifications would be within the scope of the present technology.