Position: A belt scale for measuring the weight of material being transported on a conveyor belt includes a pair of independent weigh beams, each having a cantilevered deflection section, the beams being uniquely mounted to extend inwardly of the stringers in such a way that the universal belt scale can be used with a variety of belt widths and belt loading situations. The neutral axis of the deflection section is preferably positioned in substantially the same plane as the roll supporting the belt. Alternative embodiments of a mounting allows the position of the weigh beam to be adjusted relative to the idler assembly. Alternative embodiments of an adjustable pivot allow the full scale capacity of the belt scale to be varied. The universal belt scale may also include varying the sensitivity of the weigh beam, for more accurate weighing control.
1. A universal belt scale for weighing material being transported on a conveyor belt, comprising:
a pair of opposite stringers extending parallel to one another;
a pair of cantilever beams, each having a neutral axis and being mounted at a first end to one of said stringers and supporting at a support location spaced from the first end an idler assembly, said idler assembly including a carry roller rotatably supporting a conveyor belt;
sensing means coupled to cantilever beams for measuring the deflection of the cantilever beams responsive to a weight of material being conveyed by the belt;
said cantilever beams being mounted to the stringers independently of one another to isolate each said cantilever beam from each other; and
said neutral axis of said cantilever beams lying in a first plane, the idler assembly being mounted to the beams to position a top of the carry roller in said first plane so that the sensing means accurately senses the weight of material on the belt without being appreciably affected by external factors unrelated to the weight of the material on the belt.
2. Claim 1 wherein the sensing means comprises a pair of strain weighing sensors coupled to each side of the cantilever beams for measuring the deflection of the beams to determine the weight of material being transported by the belt, the position of the carry roller in the neutral axis of the beams allowing the strain weighing load cells to measure the deflection of the beams without being affected by a force normal to the beams caused by friction between the carry roller and the belt.
3. Claim 1 wherein an entire weight of the idler assembly is supported by the beams and the beams extend inwardly of the stringers to allow the beams to deflect without interference with the stringers so that accurate measurements of the weight of material being conveyed can be obtained.
4. Claim 3 wherein the cantilever beams are capable of supporting a variety of different idler roller assemblies.
5. Claim 1 wherein a mounting member is mounted to an inside surface of each stringer, the cantilever beams forming an integral part of the mounting members, the mounting members extending toward the inside of the stringers such that deflection of the cantilever beams will not be impeded by the stringer and the weight of the material on the belt can be accurately measured.
6. Claim 5 wherein the mounting members connect the cantilever beams to the stringers such that an entire weight of the idler assembly is supported by the mounting members.
7. Claim 6 wherein each of the mounting members comprises a stringer mounting surface for securing the mounting member to a top surface of the stringer, an upward extension section extending upward from the stringer mounting surface, the cantilever beam extending horizontally from the upward extension section, a riser section extending downwardly from the cantilevered section, and an idler assembly support section extending perpendicularly from the riser section for securing the idler assembly to mounting member, the mounting members positioning the cantilevered sections inboard of the stringers such that deflection of the cantilever beam is unimpeded by the stringer and the weight of conveyed material can be determined.
8. Claim 7 wherein a first strain sensor is coupled to a top surface of the cantilevered section for measuring tensile stress in the cantilever beams when the belt transports material, and a second strain sensor is coupled to a bottom surface of the cantilevered section for measuring compressive stress, the first and second strain sensors providing an accurate means for measuring the deflection of the cantilevered section so that the weight of material being transported by the belt can be precisely determined.
9. Claim 7 wherein the strain weighing load cell is mounted between the upward extension section and the riser section to measure movement of the riser section relative to the upward extension section and thus the deflection of the cantilever beams so that the weight of material being transported by the belt can accurately be determined.
10. Claim 6 wherein the mounting member includes a means for adjusting the carry roller to correspond to said first plane such that the universal belt scale can be used with roller assemblies of varying sizes.
11. Claim 10 wherein the means for adjusting a height of the carry roller comprises an upper riser section and a lower riser section, the upper and lower riser sections having a plurality of spaced apertures such that the position of the lower riser section can be adjusted relative to the upper riser section to position the idler assembly in said first plane so that the deflection of the cantilever beams can accurately be measured.
12. Claim 10, further comprising a stack assembly mounted between the cantilever beams and the idler assembly, the stack assembly adjustably supporting the idler assembly such that the carry roller of a variety of idler roller assemblies can be positioned to correspond to said first plane to increase the accuracy of the sensing means.
13. Claim 1 wherein the carry roller is an only roller on the idler assembly and the idler assembly forms part of a weigh feeder.
14. Claim 1 wherein the cantilever beams are coupled to the stringers by means of a mounting bracket which comprises a foot portion coupled to a top of the stringer and a pair of vertical support members extending upwardly of the foot portion, said cantilever beams being coupled to a top of the vertical support members at a proximal end and supporting the idler assembly at a distal end, said sensing means comprising a strain sensor coupled to a surface of the cantilever beams for measuring the deflection of the cantilever beams.
15. Claim 1, further comprising a variable means defined by the cantilever beams for varying a sensitivity of the cantilever beams depending on the weight of material to be conveyed by the belt.
16. Claim 15 wherein the variable means comprises an aperture defined by each said cantilever beam, said aperture being located adjacent the sensing means, a diameter of the aperture being adjustable to vary a cross sectional area of the cantilever beams adjacent a sensing means to vary the resistance to bending of the cantilever beams.
17. a pair of opposite stringers extending parallel to one another;
cantilever beams coupled to each stringer at a mounting location, said cantilever beams supporting an idler assembly at respective support locations on the cantilever beams;
sensing means coupled to the cantilever beams for sensing deflection of the cantilever beams responsive to weight of material being conveyed by the belt; and
means for adjusting a distance between the mounting location and the support location on each of said cantilever beams to adjust an effective length of the cantilever beams according to a particular size and weight of a particular idler assembly being supported by the beams such that the sensing means are capable of accurately determining the weight of material being transported by the belt.
18. Claim 17 wherein effective lengths of the cantilever beams can be adjusted to accurately weight the material being transported regardless of a specific type of material being transported, a size of the idler assembly being supported by the beams, or rates of speed at which the belt may travel.
19. Claim 18, wherein the sensing means comprises a strain sensor mounted to a top side of each cantilever beam such that when the cantilever beams deflect as a result of weight on the belt, the strain sensors measure the deflection so that the weight of the material on the belt can be calculated.
20. Claim 19 wherein a plurality of strain sensors are coupled to each cantilever beam at different locations.
21.a pair of opposite stringers extending parallel to one another;
a pair of cantilever beams each having a neutral axis, one of said cantilever beams being coupled to each stringer, said cantilever beams supporting an idler assembly which includes a carry roller rotatably supporting a conveyor belt, said cantilever beams supporting said idler assembly so that a top of the carry roller is positioned in a coplanar relationship with respect to a neutral axis of the beams such that a weight of material transported by the belt can be accurately measured;
sensing means coupled to each cantilever beam for sensing deflection in the beams and determining the weight of material being conveyed by the belt; and
said cantilever beams being mounted to said stringers and extending inwardly thereof to support said idler assembly at locations inboard of the stringers such that the beams can deflect without interference from the stringers to allow said carry roller to be positioned between said stringers, the cantilever beams being the sole means for supporting the idler assembly such that the weight of material on the belt can be accurately measured by the sensing means without being affected by additional support structures.
22. The belt scale according to claim 21 wherein the top of the carry roller is positioned in a coplanar relationship with respect to a neutral axis of the beams such that the weight of material transported by the belt can be accurately measured.
23. Claim 21 wherein the idler assembly is supported without a need of a cross member coupled between the stringers.
24. A method of installing a universal belt scale on an existing idler assembly of an operating belt conveyor system while the belt is moving, comprising the steps of:
securing a pair of independent weigh beams to opposite stringers, each said weigh beam having a mounting surface at a first end being secured to a top side of one said stringer;
securing each said independent weigh beams to an existing, operating idler assembly by means of a hinged plate adjustment bracket, each said weigh beam having a lower support portion for securing to the existing idler, said hinged plate adjustment bracket coupling the idler assembly to the support portion;
removing a preexisting mounting means previously used to secure the idler assembly to said stringers; and
adjusting the hinged plate adjustment bracket to vary a position of the idler assembly relative to the weigh beam to provide clearance between the idler assembly and the stringers and to position a roll of the idler assembly in substantially the same plane as a neutral axis of the weigh beam.
25.a pair of opposite stringers extending parallel to one another and providing a primary structural support for a belt conveying means;
a pair of vertically oriented upstanding members coupled independently to each stringer;
a cantilever beam extending from each said upstanding member for supporting an idler assembly which includes a carry roller rotatably supporting a conveyor belt, said cantilever beam creating a moment arm having a length determined by a position on the cantilever beam where the idler assembly is supported and a pivot point on the upstanding member about which the moment arm rotates, the length of the moment arm defining a full scale capacity of the belt scale;
sensing means coupled to a side of each said upstanding member for sensing a moment arm force exerted on the cantilever beam from a weight of material being conveyed by the belt;