1. Field of the Invention
This invention relates to conveyor belts and, more particularly, to modular plastic conveyor belts formed of rows of plastic belt modules pivotally interlinked by transverse pivot rods.
2. Discussion of the Related Art
Because they do not corrode, are lightweight, and easy to clean, unlike metal conveyor belts, plastic conveyor belts are used widely, especially in conveying food products. Modular plastic conveyor belts consist of molded plastic modular links, or belt modules, that can be arranged side by side in rows of selectable width. A series of spaced apart link ends extending from each side of the modules include aligned apertures to accommodate a pivot rod. The link ends along one end of a row of modules are interconnected with the link ends of an adjacent row. A pivot rod journaled in the aligned apertures of the side-by-side and end-to-end connected modules forms a hinge between adjacent rows. Rows of belt modules are connected together to form an endless conveyor belt capable of articulating about a drive sprocket.
In many industrial applications, conveyor belts are used to carry products along paths including curved segments. Belts capable of flexing sidewise to follow curved paths are referred to as side-flexing, turn, or radius belts. As a radius belt negotiates a turn, the belt must be able to fan out because the edge of the belt at the outside of the turn follows a longer path than the edge at the inside of the turn. In order to fan out, a modular plastic radius belt typically has provisions that allow it to collapse at the inside of a turn or to spread out at the outside of the turn.
Apertures slotted in the direction of travel of the belt are commonly provided in the link ends on at least one side of the modules to facilitate the collapsing and spreading of the belt.
The requirement of following a curved path causes problems not found in straight-running belts. As one example, radius belts, especially if tightly tensioned or running fast and lightly loaded, tend to rise out of the conveyor support around a turn. As another example, because belt pull is concentrated in the outer portion of the belt as it rounds a turn, outer link ends are more likely to fail unless otherwise strengthened or bolstered.
There are other problems with some common belt designs. For example, stresses can be molded into the plastic modules during the manufacturing process. Sharp, as opposed to curved, junctions between molded features on a belt module are more likely to form concentrated stress regions. When such modules make up a conveyor belt, operation of the belt increases the stress in those regions. In a radius belt, in which the pulling load is unevenly distributed across the width of the belt as it rounds a turn, the problem is exacerbated. One way to solve the problem is to add more material to the belt, but that makes the belt heavier, increases the production cost due to the larger molding cycle and closes in some of the desirable open area that allows for drainage or air flow.
Another problem with some structures of radius belts is compression of the modules transverse to the direction of belt travel. A radius belt bricklayed to a width of, for example one meter, may compress by three to four millimeters as the belt rounds a turn, which can cause the belt to come out of the conveyor support. Belts having a corrugated configuration as shown in U.S. Pat. No. 5,372,248 to Horton are especially susceptible to bending and compression of this type.
What is needed is a modular radius conveyor belt that is resistant to compression and that improves the engagement of the belt to the drive sprocket.
The present invention meets the above-described need by providing an endless conveyor belt formed of plastic belt modules and capable of following a curved path. The modules include first and second module surfaces, i.e., a top, product-conveying surface and a bottom, sprocket-driven surface. An intermediate section extends across the width of each module transverse to the direction of belt travel. The intermediate section is formed in part by a web and in part by a thin, corrugated strip having a pair of essentially parallel walls. The corrugated strip forms a series of regularly spaced alternating ridges and valleys along each wall. Link ends extend outward from the ridges on each wall of the corrugated strip. Each link end has a leg portion attached at a ridge of the strip and a thick distal portion at the end of the link end distant from the corrugated strip. Transverse holes in the link ends extending from respective walls of a module are aligned to accommodate a pivot rod. When the link ends of consecutive rows of side-by-side modules are intercalated, the pivot rod serves as a hinge pin in a hinged joint between consecutive interlinked rows. To permit the belt to follow a curved path, the pivot rod opens in at least one of the link ends extending from one of the walls of the corrugated strip, which are slotted longitudinally in the direction of belt travel.
The belt is driven by the engagement of the sprocket tooth with the curved outside surface of the link ends. The link end engaged by the sprocket tooth is subjected to a compressive force rather than an undesirable tensile force. Thus, the link ends provide pull strength, resistance to belt, sprocket wear, and sprocket drivability. As an alternative, a central portion of a link end disposed in the middle of the belt modules may also engage with a tooth on the drive sprocket. Because the mid modules do not have to collapse fully, they may be formed with a thicker and fully straight cross-rib.
Each wall of the corrugated strip forms a series of arched recesses with the leg portions of the link ends. The recesses are large enough to provide room for a thick link end of an interlinked module of an adjacent row to collapse into the recess or to rotate as belt rows fan out going around a turn. Because the recesses along one wall overlap in a transverse direction with the recesses along the other wall, additional space for collapsing is provided.
The invention is illustrated in the drawings in which like reference characters designate the same or similar parts throughout the figures of which:
Referring now to the drawings, FIGS. 1 to 7 show a first embodiment of a portion of a modular belt 20 of the present invention. The portion of the modular belt 20 shown is formed from molded plastic modules 23, 26 and 29. For reference, the direction of belt travel is indicated by arrow 32; however, the belt of the present invention may be conveyed in either direction. A pivot rod 35 connects adjacent belt modules by passing through openings in the modules disposed transverse to the direction of belt travel.
As shown in
The first link ends 41 include a leg portion 59 connected to an intermediate section 62 and extending to a distal head portion 65. In a similar manner, the second link ends 44 include a leg portion 68 connected to the intermediate section 71 and extending to a distal head portion 74.
With respect to the orientation shown in FIGS. 2 to 4, the intermediate section 38 formed of the stiffening web 47 and the corrugated portion 50 is comprised of an upper surface 77 extending to and meeting with opposed left and right walls 80 and 83 which, in turn, meet with a lower surface 86 of the module. The left wall 80 is comprised of an upper wall 89, which is part of the stiffening web 47, and extends downwardly to a curved wall 92 which forms into a lower vertical wall 95. The curved wall 92 and the lower vertical wall 95 are part of the corrugated portion 50 of the intermediate section 38. The lower vertical wall 95 extends to the lower surface 86 of the module which, in turn, extends to and meets with the right vertical wall 83.
As shown in
An opening 107 is defined between spaced apart sides 110, 113 of adjacent link ends. At a distal end 116, the ends of adjacent links form the mouth 119 of the opening 107. At the opposite end 122, the opening 107 terminates in the multi-level surface defined by the web 47 and corrugated portion 50 as described above. The top level of the surface (best shown in
In
Returning to
The plurality of second link ends 44 extend from and touch the belt module 26 in the opposite direction from the first link ends 41. The second link ends 44 have the same overall shape as the first link ends 41 (except for the last link end 45) and are designed to fit into the openings between the first link ends 41 such that adjacent belt modules can be intercalated and pivotally connected by the pivot rods 35.
The first and second link ends are respectively spaced apart at a first width and each link end is a second width wide, so that the first width is more than 0.01 inches greater than the second width. In an exemplary embodiment, the first and second link ends each comprise a head portion and a leg portion, wherein the legs of adjacent link ends are spaced apart at a first width and each link end leg is a second width wide, and wherein the first width is more than 0.01 inches greater than the second width.
Notably, a plurality of spaces, that extend from a top surface of the belt to a bottom surface of the belt, are bound by a front wall of the web, an outer end of the first link end, and the side walls of the second link ends in a series of intercalated belt modules, wherein at least some of the spaces of the intercalated belt modules have diameter greater than zero and an area greater than zero at least when the belt follows a curved path.
As shown in
The last link end 45 of the belt module 26 includes a second opening 140 disposed around opening 137 to provide for countersinking a head (not shown) at the end of the pivot rod shaft 138.
The back surface of the last link end 45 includes a rounded surface 143 that provides clearance for pivoting an adjacent link end 45.
In
The outer ends 104 of the link ends 41 and 44 are radiused in a smooth rounded surface 146. The rounded surface 146 preferably comprises a rounded surface having a constant radius and provides a driving surface for engagement with the drive sprocket 149, as described herein.
Also, the curvature of the outer ends 104 of the link ends enables the links to clear the web 47 when the adjacent modules collapse along the edge. The clearance enables the link ends to extend under the web 47 into the space defined by the corrugated portion 50 (best shown in
Turning to
The belt module 200 includes link ends 206, 207 which are supported by an intermediate section 208. The link ends 206 have a slot 209 disposed transverse to the direction of belt travel indicated by arrow 211. Link ends 207 have a transverse opening 213 that corresponds to the shaft 138 of pivot rod 35.
As shown in
As shown in
The link ends 207 have the transverse opening 213 capable of receiving the pivot rod 35. Link ends 206 have the transverse slot 209 that is oblong and extends in the direction of belt travel such that the pivot rod 35 can move inside the slot 209 to pivot and facilitate collapsing.
The engagement of the face 236 on the central portion 215 with the tooth 148 on the drive sprocket 149 (shown in
Turning to
As an option, the belt module 300 includes a plurality of openings 331 that provide for reducing the weight and material cost for the belt and provide open areas for cleaning the belt. The vertical openings 331 in the link ends 306 are shown in
Turning to
In
For belts having a pitch greater than or equal to 1.5 inches, the openings created in the belt grid may allow for fingers to penetrate the grid.
In the present invention, for belts having pitches greater than or equal to 1.5 inches, extending the upper wall 489 outward from the cross-rib 438 reduces the size of space 400. The upper wall 489 is sized so that when the belt 420 is fully extended lengthwise the space 400 has critical opening widths or diameter less than 10 mm. Critical opening width or diameter is defined as the distance of the opening across its smallest dimension.
The extended upper wall 489 is sized to reduce the size of the opening yet allows the belt 420 to collapse without obstruction. The curvature of the link end from the top surface provides for nesting of the link end beneath the upper wall 489.
In
Accordingly, a radius belt 420 suitable for larger pitch (≧1.5″) radius belt applications has been disclosed. The belt 420 has an extended cross-rib 438 that reduces the space 400 to less than 10 mm width so as to prevent fingers of a user from penetrating the belt grid.
While the invention has been described in connection with certain preferred embodiments, it is not intended to limit the scope of the invention to the particular forms set forth, but, on the contrary, it is intended to cover such alternatives, modifications, and equivalents as may be included within the spirit and scope of the invention as defined by the appended claims.
The present application is a continuation of U.S. patent application Ser. No. 10/969,983, filed Oct. 22, 2004, which is a continuation of U.S. patent application Ser. No. 10/429,031, filed May 5, 2003, now U.S. Pat. No. 6,896,126, which is a continuation of U.S. patent application Ser. No. 10/282,068, filed Oct. 29, 2002, now abandoned, which is a continuation of U.S. patent application Ser. No. 09/874,589, filed Jun. 5, 2001, now U.S. Pat. No. 6,523,680, which is a continuation-in-part application claiming priority to U.S. patent application Ser. No. 09/579,090, filed May 25, 2000, now U.S. Pat. No. 6,330,941 and entitled “Radius Conveyor Belt,” all of which are incorporated herein by reference in their entireties.
Number | Date | Country | |
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Parent | 10969983 | Oct 2004 | US |
Child | 11907618 | Oct 2007 | US |
Parent | 10429031 | May 2003 | US |
Child | 10969983 | Oct 2004 | US |
Parent | 10282068 | Oct 2002 | US |
Child | 10429031 | May 2003 | US |
Parent | 09874589 | Jun 2001 | US |
Child | 10282068 | Oct 2002 | US |
Number | Date | Country | |
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Parent | 09579090 | May 2000 | US |
Child | 09874589 | Jun 2001 | US |