Modular curve-top conveyor belt

Abstract

A conveyor belt constructed of rows of belt modules having convexly curved product-supporting surfaces. When articulating about sprockets, the product-supporting surfaces from row to row form a continuous circular arc that allows the edge of a transfer plate or a scraper to be positioned close to or against the belt's product-supporting surfaces.

Description

TECHNICAL FIELD The invention relates generally to power-driven conveyors and more particularly to modular conveyor belts with curved top surfaces. BACKGROUND Modular conveyor belts with curved top surfaces in each belt row are used to enable tight transfers of products off the ends of the belts onto transfer plates. The top surfaces of the individual belt rows are convexly curved so that the belt exhibits a constant curvature as it wraps around sprockets at its exit from a carryway. Because the curvature is constant, another conveyor can be positioned close to the top surface to receive conveyed products from the belt. Or a transfer plate can be positioned close to the top surface to strip conveyed products from the belt at the exit end of the carryway. The gap between the edge of the transfer plate and the top surface of the belt remains constant as the belt articulates about the sprockets. With a conveyor belt having a planar top surface, the gap between a transfer plate and the top surface continually increases and decreases as the belt articulates about sprockets. Thus, the transfer of products from the belt onto the transfer plate is not as smooth as with the curve-top belt. Not only does the curve-top belt enable smooth product transfer, but it is easier to scrape clean because a fixed scraping edge can be positioned against the belt rounding the sprockets. Spiral belt conveyors are especially useful for conveying food products through freezers or ovens because they produce a long conveying path with a small footprint. Because the vertical distance between consecutive belt tiers on the helical path about the drive drum is small, airflow through a heavily loaded spiral belt can be largely obstructed. And airflow can be important for uniform heating or cooling of conveyed products. So many spiral belts have large open areas, but at the expense of support area on the productsupporting belt surface. Less support area means higher pressures against the undersides of the conveyed products. If the undersides are soft, as for bread or doughs, the support areas of the belt can cause undesirable indentations to form in the product undersides. Increased support area, which decreases open area and airflow, is often necessary. And even with rigid products, such as baked cookies and frozen dough, crumbs and pieces of dough can get caught in the large open areas, which scrapers can't access. Thus, there is a need for a curve-top conveyor belt that provides both sufficient airflow and increased product support and is easy to clean with a scraper. SUMMARY One version of a conveyor belt module extending in length in a conveying direction from a first end to a second end, laterally in width from a first side to a second side, and in thickness from a top to a bottom and embodying features of the invention comprises a set of first hinge elements spaced apart laterally along the first end across intervening first gaps and a set of second hinge elements spaced apart laterally along the second end across intervening second gaps laterally offset from the first gaps. Each of the first and second hinge elements includes a pair of laterally spaced arms, each extending in the conveying direction from an interior end to an outer end, a nose connected between the outer ends of the pair of arms, a crossbar connected between the interior ends of the arms, and links connected between the interior ends of the arms of the first hinge elements and the interior ends of the nearest arms of the second hinge elements. The first and second hinge elements and the links define a convex product-supporting surface at the top of the conveyor belt module that has a peak between the first and second ends of the conveyor belt module. The crossbars are recessed below the convex product-supporting surface to aid the flow of air at or the draining of fluids from the product-supporting surface of the conveyor belt module. One version of a conveyor belt embodying features of the invention comprises rows of side-by-side conveyor belt modules, each row extending in length in a conveying direction from a first end to a second end and laterally in width from a first side to a second side and in thickness from a top to a bottom. Each row includes a set of first hinge elements spaced apart laterally along the first end across intervening first gaps and a set of second hinge elements spaced apart laterally along the second end across intervening second gaps laterally offset from the first gaps. Each of the first and second hinge elements includes a pair of laterally spaced arms, each extending in the conveying direction from an interior end to an outer end, a nose connected between the outer ends of the pair of arms, a crossbar connected between the interior ends of the arms, and links connected between the interior ends of the arms of the first hinge elements and the interior ends of the nearest arms of the second hinge elements. The offset in the conveying direction between the crossbars of the first hinge elements and the crossbars of the second hinge elements decreases from the first side toward the second side until the crossbars and the links converge into alignment to form a linear lateral spine extending from a point between the first and second sides to the second side. The first hinge elements of a row interleave with the second hinge elements of an adjacent row to join the rows together at hinge joints. The first and second hinge elements and the links of each row define a convex product-supporting surface at the top of the row that has a peak between the first and second ends of the row The crossbars are recessed below the convex product-supporting surface to aid the flow of air at or the draining of fluids from the product-supporting surface of the conveyor belt. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a top plan view of a portion of a curve-top conveyor belt embodying features of the invention. FIG. 2 is a side elevation view of the curve-top conveyor belt of FIG. 1 articulating about sprockets and being scraped clean by a scraper. FIG. 3 is an isometric view of an inside-edge conveyor belt module of the conveyor belt of FIG. 1. FIG. 4 is a top plan view of the inside-edge portion of the conveyor belt module of FIG. 3. FIG. 5 is a side elevation view of the conveyor belt module of FIG. 3. FIG. 6 is an isometric view of an outside-edge module for the conveyor belt of FIG. 1. FIG. 7 is a top plan view of the outside-edge portion of the conveyor belt module of FIG. 6. DETAILED DESCRIPTION A conveyor belt 10 suitable for use in a spiral conveyor is shown in FIG. 1. The belt 10 is constructed of a series of rows 12 of a single belt module or of multiple side-by-side belt modules. For narrow belts, each row 12 can comprise a single module; for wider belts, two or more modules form each row in a bricklay pattern with the other rows. Hinge elements 14,15 at opposite ends of each row 12 are interleaved with hinge elements of adjacent rows and connected at hinge joints 16 at which the belt can articulate. Rod holes through each of the interleaved hinge elements are aligned to form a lateral passageway at each hinge joint 16. A hinge rod 18 received in the lateral passageway connects the adjacent rows 12 together. The rod holes at one or both ends of the rows are elongated in a conveying direction 20 to allow the rows to collapse together. As shown in FIG. 1, the belt rows 12 at the right-hand side of the drawing traveling along a straight path are maximally separated across the entire width of the belt. In a turn, as at the left-hand side of FIG. 1, the rows 12 collapse together at the inside of the turn and are maximally separated at the outside of the turn where the path length is greater. FIG. 1 depicts the belt 10 traveling toward the left as viewed in the figure and tangentially entering a helical path in a spiral conveyor. But the belt 10 is bidirectional and can be run in either direction. Straight-running belts with nonelongated rod holes and some of the other features to be described can also be made. Further details of the conveyor belt 10 of FIG. 1 are shown in FIG. 2. The belt 10 is shown exiting a carry way 22 at a belt exit end 23 and articulating about sprockets 24 on its way to a lower belt return. The top product-supporting surface 26 is convexly shaped. The convex surface 26 has a peak 28 between first and second opposite ends 30, 31 of each belt row 12. The convex shape of the top surface 26 is an arc of a circle so that, as the belt 10 articulates about the sprockets 24, the top surface of the belt assumes a longer continuous circular arc about the sprockets. For that reason, a fixed scraper 32 can be positioned with its scraping edge 34 against the top surface 26. Similarly, a transfer plate (not shown) could be positioned close to the top surface 26 of the belt 10 slightly higher up toward the carry way 22 to strip products from the belt as they exit the carryway at the belt exit end 23. Or another conveyor can be positioned close to the belt 10 at the belt exit end 23 to receive products. An inside-edge conveyor belt module is shown in FIG. 3. The belt module 40 extends in length in the conveying direction 20 from a first end 42 to a second end 43, laterally in width from a first side 44 to a second side 45, and in thickness from a top 46 to a bottom 47. When the inside-edge belt module 40 is used in a wide conveyor belt in which there are two or more bricklaid modules per belt row, its width from the first side 44 to the second side 45 alternates from row to row. The width of the belt module 40 is changed by cutting the module along a line parallel to the conveying direction 20 inward of the second side 45 and removing the separated hinge elements 14,15. Of course, it's possible to mold modules of different widths. The conveyor belt module 40 has a set of first hinge elements 48 spaced apart laterally along the first end 42 across intervening first gaps 50. Similarly, a set of second hinge elements 49 are spaced apart laterally along the second end 43 across second gaps 51. The first gaps 50 are laterally offset from the second gaps 51. As better shown in FIG. 4, each of the first and second hinge elements 48, 49 has a pair of laterally spaced arms 52 that extend in the conveying direction 20 from an interior end 54 to a nose 56 at an outer end 55. The nose 56 is connected between the outer ends 55 of the pair of arms 52. A crossbar 60 is connected between the interior ends 54 of the two arms 52. Links 62 are connected between the interior ends 54 of the arms 52 of the first hinge elements 48 and the nearest arms of the second hinge elements 49. Near the first side 44 of the belt module 40, the links 62 are oblique to the conveying direction 20. The first and second hinge elements 48, 49 and the links 62 define a product-supporting surface 26 at the top of the module 40. The crossbars 60 are recessed below the product-conveying surface to aid the flow of air at and the draining of fluids from the product-supporting surface of the conveyor belt module 40. The top surface of the crossbars 60 is concavely curved in FIG. 3 but could be flat instead. And, although the belt 10 in FIG. 1 has a lot of open area, the dimensions of each of the openings 66 through the thickness of the belt are small enough to lessen the tendency of the bottom surfaces of less rigid products to sag into the openings. That reduces the formation of indentations in the bottom surfaces of less rigid products. Furthermore, as shown in FIG. 5, the product-supporting belt surface 26 is convexly curved with a peak 68 between the first and second ends 14,15. The convex shape of the product-supporting belt surface 26 forms a circular arc. The diameter of the sprocket 24 in FIG. 2 determines its curvature, which is related to the lesser curvature of the belt's convex product-supporting surface 46 such that the product-supporting surface of the belt 10 forms a continuous circular arc around the sprockets 24. Belt-edge structure 67 forming the first side 44 of the inside-edge belt module 40 is flat at the top and recessed below the level of the product-supporting surface 26. A ramp 69 declines from the product-supporting surface 26 to the top of the belt-edge structure 67. The recessed belt-edge structure 67 allows sideguards, for example, to be mounted along the first side 44 of the module 40. A protrusion 70 extends laterally outward of the first side 44 of the belt module 40, as shown in FIGS. 3 and 4. The protrusions 70 along the first sides 44 of the belt rows 12 in FIG. 1 are engaged and driven in the conveying direction 20 up or down a cylindrical drive drum along a helical path by vertical drive bars 72 on the periphery of the drum in a spiral conveyor system. The drum's vertical drive bars 72 are spaced apart an integral multiple of the distance between consecutive protrusions 70 on the collapsed inner first side 44 of the belt 10. Belts without the protrusion 70 at the first sides 44 can be used in friction-driven spiral-conveyor systems or in radius (side-flexing) conveyors. An outside-edge conveyor belt module 74 is shown in FIG. 6. The outside-edge belt module 74 extends laterally in width from a first side 75 to a second side 77. Like the insideedge module 40 of FIGS. 3-5, the outside-edge module 72 has a similarly curved convex top surface 76. Also, like the inside-edge module 40, the outside-edge module 74 can be cut to width for bricklaying. Alternatively, the inside- and outside-edge modules 40, 74 may be molded as a single wide module for use in narrow belts with only that single module forming each row. In that case, each wide module includes an inside-edge portion as represented by FIG. 3 unitarily formed with outside-edge portion as represented by FIG. 6. As FIGS. 6 and 7 show, belt-edge structure 79 at the second side 77 of the outsideedge belt module 74 is flat at the top and recessed below the level of the product-supporting convex surface 76. Ramps 81, 83 decline from the convex surface 76 to the top of the beltedge structure 79. The recessed belt-edge structure 79 allows sideguards, for example, to be mounted along the second side 77 of the module 74. The noses 78 of the first and second hinge elements 14,15 of the outside-edge module 74 are identical and broader at their tip ends than the noses 56 at the tip ends of the first and second hinge elements near the first side 44 of the inside-edge module 40 of FIG. 4. The inside-edge module's noses 56 accommodate the tight collapse of the conveyor belt 10 (FIG. 1) at the inside of a turn. The noses of the first and second hinge elements 14,15 closest to the first side 44 have outermost portions 80 that are recessed below the top surface 46 to fit beneath module structure of an adjacent module for a tight inside-edge collapse. As shown in FIG. 3, the first and second hinge elements 14,15 nearest the second side 45 of the inside-edge module 40 are identical to the two-arm hinge elements of the outside-edge module 74 of FIG. 6. The first and second hinge-elements 14,15 of the inside-edge module 40 and the dimensions of the first and second gaps 50, 51 change gradually from hinge element to hinge element across the width of the module to allow the belt 10 to fan out in turns. And all the two-arm hinge elements of both the inside-edge and outside edge modules 40, 74 are chamfered at their noses. 5          As better shown in FIG. 7, the crossbars 60 are recessed below the top surface 76 of the outside-edge module 74. The links 62', which do form part of the top surface 76 are laterally aligned with the crossbars 60 to form a linear lateral spine across the module's width. The links 62' and the first and second hinge elements 14,15 are identical to those at the second side 45 of the inside-edge module 40 of FIG. 3. The outside-edge module 74 of 10 FIG. 7 is further characterized by single-arm hinge elements 82 along the first and second ends.

Claims

1. A conveyor belt module extending in length in a conveying direction from a first end to a second end and laterally in width from a first side to a second side and in thickness from a top to a bottom and comprising:a set of first hinge elements spaced apart laterally along the first end across intervening first gaps;a set of second hinge elements spaced apart laterally along the second end across intervening second gaps laterally offset from the first gaps;wherein each of the first and second hinge elements includes:a pair of laterally spaced arms, each extending in the conveying direction from an interior end to an outer end;a nose connected between the outer ends of the pair of arms;a crossbar connected between the interior ends of the arms;a plurality of links connected between the interior ends of the arms of the first hinge elements and the interior ends of the nearest arms of the second hinge elements;wherein the first and second hinge elements and the links define a convex productsupporting surface at the top of the conveyor belt module that has a peak between the first and second ends of the conveyor belt module; andwherein the crossbars are recessed below the convex product-supporting surface to aid the flow of air at or the draining of fluids from the product-supporting surface of the conveyor belt module.

2. The conveyor belt module as claimed in claim 1 wherein the crossbars are aligned with the links to define a linear spine extending laterally from the first side to the second side.

3. The conveyor belt module as claimed in claim 1 wherein the offset in the conveying direction between the crossbars of the first hinge elements and the crossbars of the second hinge elements is greater at the first side than at the second side.

4. The conveyor belt module as claimed in claim 3 wherein the crossbars of the first and second hinge elements are laterally aligned at the second side.

5. The conveyor belt module as claimed in claim 1 wherein the convex product-supporting surface defines an arc of a circle.

6. The conveyor belt module as claimed in claim 1 comprising a protrusion extending laterally outward of the first side of the conveyor belt module.

7. The conveyor belt module as claimed in claim 1 comprising:a set of third hinge elements spaced apart across third gaps along the first end between the second side of the conveyor belt module and the set of first hinge elements and wherein each of the third hinge elements has a single arm;a set of fourth hinge elements spaced apart across fourth gaps along the second end between the second side of the conveyor belt module and the set of second hinge elements and wherein each of the fourth hinge elements has a single arm;wherein the lateral dimension of the third and fourth gaps is less than the lateral dimension of the first and second gaps.

8. A modular conveyor belt comprising:a plurality of rows of side-by-side conveyor belt modules, each row extending in length in a conveying direction from a first end to a second end and laterally in width from a first side to a second side and in thickness from a top to a bottom and including: a set of first hinge elements spaced apart laterally along the first end across intervening first gaps;a set of second hinge elements spaced apart laterally along the second end across intervening second gaps laterally offset from the first gaps;wherein each of the first and second hinge elements includes:a pair of laterally spaced arms, each extending in the conveying direction from an interior end to an outer end;a nose connected between the outer ends of the pair of arms;a crossbar connected between the interior ends of the arms;a plurality of links connected between the interior ends of the arms of the first hinge elements and the interior ends of the nearest arms of the second hinge elements;wherein the offset in the conveying direction between the crossbars of the first hinge elements and the crossbars of the second hinge elements decreases from the first side toward the second side until the crossbars and the links converge into alignment to form a linear lateral spine extending from a point between the first and second sides to the second side;wherein the first hinge elements of a row interleave with the second hinge elements of an adjacent row to join the rows together at hinge joints;wherein the first and second hinge elements and the links of each row define a convex product-supporting surface at the top of the row that has a peak between the first and second ends of the row; andwherein the crossbars are recessed below the convex product-supporting surface to aid the flow of air at or the draining of fluids from the product-supporting surface of the conveyor belt.

9. The modular conveyor belt as claimed in claim 8 comprising a protrusion extending laterally outward of the first side of each row.

10. The modular conveyor belt as claimed in claim 8 wherein each of the rows comprises: a set of third hinge elements having a single arm extending from the spine and spaced apart across third gaps along the first end between the second side of the row and the set of first hinge elements;a set of fourth hinge elements having a single arm extending from the spine and spaced apart across fourth gaps along the second end between the second side of the row and the set of second hinge elements;wherein the first and third hinge elements of a row interleave with the second and fourth hinge elements of an adjacent row to join the rows together at the hinge joints.

11. The modular conveyor belt as claimed in claim 10 wherein the first and third hinge elements of each row have aligned holes along the first end of each row and wherein the second and fourth hinge elements of each row have aligned holes along the second end of each row and wherein the interleaved hinge elements of adjacent rows form lateral passageways through the aligned holes and wherein the modular conveyor belt includes hinge rods received in the lateral passageways to join adjacent rows together at the hinge joints.

12. The conveyor belt as claimed in claim 11 wherein the aligned holes along the first end of each row are elongated in the conveying direction to allow the conveyor belt to collapse at the inside of a turn.

13. The conveyor belt as claimed in claim 8 wherein the convex product-supporting surface of each row defines an arc of a circle.

14. The conveyor belt as claimed in claim 8 comprising first belt-edge structure at the first side of each row and second belt-edge structure at the second side of each row, wherein the first and second belt-edge structures are recessed below the level of the convex product-supporting surface.

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