Spiral conveyor and spiral conveyor drum drive

Abstract

The spiral conveyor has a drum (110) that extends from a base (112) to a top (114) and has a transition height. The drum (110) includes a plurality of drive bars (120), each having a drive side parallel to an axis of rotation (a) of the drum (110). The drive sides extend longitudinally from the transition height to a top (114) of the drum (110). The drive bars (120) are spaced apart circumferentially around the drum (110). The drum (110) includes a plurality of transition members (130), each transition member (130) including a drive surface. At least a portion of each drive surface is angled relative to the axis of rotation (a) of the drum (110) such that, over an infeed distance, the circumferential location of the drive surface of each transition member (130) advances by a collapse distance of a corresponding modular belt.

Description

[Technical field]

[0001] The present invention relates to spiral conveyors, and more particularly to a direct drive drum for a spiral conveyor system. [Background technology]

[0002] Conveyor belts that run in a spiral path (so-called "spiral conveyors") are often used to transport goods in climate-controlled environments for extended periods of time, for example, spiral conveyors are used to transport food products in freezers, proofing rooms, etc.

[0003] Some previous spiral conveyors were driven at a location in the belt path outside the spiral, which requires very high belt tension near the drive location to pull the belt through the spiral. To reduce belt tension, other spiral conveyors have been driven using an overdrive arrangement in which the conveyor belt follows a spiral path around a central drum, which drives the belt by friction with the inner edge of the belt. The central drum is driven (i.e., the belt is allowed to slip) at a speed greater than the belt speed. In this way, the belt is driven along the entire spiral path around the central drum, eliminating the need for high maximum belt tension at the drive location. However, overdrive systems for spiral conveyors can cause significant wear on the driven edge of the conveyor belt and the outer surface of the drum, due to the constant slippage of the belt on the drum. Furthermore, a second drive must be used to determine the belt speed, in addition to the friction drum.

[0004] Furthermore, the coefficient of friction between the drum and the belt is difficult to predict, as it depends on factors such as the belt material, the cage bar material, temperature, humidity, surface roughness, surface shape, contact pressure, and speed. Another influence on the coefficient of friction comes from the goods being conveyed. For example, when conveying food products such as marinated meat, fat and other drips may come into contact with the drum, in which case the coefficient of friction between the drum and the belt drops significantly. In a more specific example, a steel drum and a polypropylene belt have a coefficient of friction of about 0.3, but the inflow of fat-like material from the meat being conveyed between the drum and the belt can reduce the coefficient to below 0.1. The driving force that the drum exerts on the belt drops in proportion to the change in the coefficient of friction. Ultimately, such a change in driving force is likely to cause production interruptions due to belt lift, belt breakage, or both.

[0005] On the other hand, the friction between the belt and its support can change over time. Here, it is very likely that debris from the product being transported on the belt will contaminate the support. In most cases, the friction between the belt and the support increases over time. At some point, the friction between the belt and the drum used to drive it may no longer be sufficient to overcome the friction between the belt and the support. This can cause production stoppages.

[0006] Other spiral conveyor systems use positive drives, where a rotating drum contains drive bars on its circumference that directly engage structures on the inside edge of the driven conveyor belt. Such positive drive systems do not depend on slippage or friction between the drum and belt, and therefore do not suffer from the disadvantages of overdrive systems. However, positive drive systems have a problem where the conveyor belt contacts the drum (the "infeed"). At the infeed, as the inside edge of the belt collapses into the turning radius of the drum, there is a momentary difference between the pitch of the drive bars on the drum and the pitch of the structures on the inside edge of the belt. This difference in pitch can cause chatter, sudden increases in belt tension, etc., which can lead to belt breakage.

[0007] From US 2017 / 0022012 A1 and related patent application publications US 2018 / 0290833 A1 and US 2019 / 0308817 A1, positive drive systems, also known as direct drive systems, for spiral conveyor belts are known in which drive elements engage and drive as well as support the modular conveyor belt, in particular in the form of profiled ribs and cage bars forming part of a drive drum. The drive drum may also include a continuous circumferential ring extending between the terminal ends of the ribs and the inlet end of the drum, thereby connecting the drive elements and providing a belt support surface.

[0008] WO 2013 / 142136 A1 discloses a similar positive drive system in which combined drive and support elements engage, drive and support a modular conveyor belt, with additional support elements being disposed between the combined drive and support elements.

[0009] A technical problem encountered with such known positive or direct drive systems, when used to drive modular conveyor belts ("modular" in this context means composed of a plurality of individual belt modules), is that they do not allow sufficient slippage between the drive drum and the conveyor belt, resulting in unwanted tension in the modular conveyor belt, particularly when the modular conveyor belt changes direction or changes in belt travel.

[0010] When the direct drive drum forces the conveyor belt from a linear belt movement in a circumferential direction, i.e., around the direct drive drum as in a spiral conveyor system, the individual belt modules of the modular conveyor belt are forced to move closer together towards their (inner) ends that are supported close to the direct drive drum, and to move apart towards their (outer) ends that are further from the direct drive drum. Thus, during this "collapse phase", the distance between the individual belt modules of the conveyor belt must change, while the distance between the individual drive elements of the drive drum (drive elements that engage the conveyor belt at or between its individual belt modules) remains constant. As the individual belt modules are forced together and apart at the same time, movements occur within the modular conveyor belt and between the modular conveyor belt and the direct drive drum. Furthermore, with some direct drive solutions, there is a risk that the drive elements located on the conveyor belt will not properly mate with the corresponding drive elements located on the drum. This creates unexpected forces that can damage the belt and / or the drive bars. Over time, such damage can lead to failure of the entire spiral system.

[0011] When the modular conveyor belt changes from a circular belt travel to a linear direction as it leaves the direct drive drum during the disengagement phase, the individual belt modules must realign and move out of contact with the outer surface, particularly the drive elements of the direct drive drum which also generate tension. The exit tension may also be too low and need to be increased slightly.

[0012] Therefore, there is a long-felt need for a positive drive spiral conveyor having an infeed that cleanly engages the belt. Summary of the Invention

[0013] In a first aspect, it is an object of an embodiment of the present invention to provide a direct drive drum for better control of tensions generated within a modular conveyor belt, and in particular to allow more engagement tolerance during the collapse phase of the modular conveyor belt.

[0014] This object is achieved by providing a spiral conveyor according to independent claim 1 or a spiral conveyor according to independent claim 11. Particularly advantageous embodiments of the invention result from the dependent claims.

[0015] In some embodiments, the invention may be embodied as a spiral conveyor having a rotating cylindrical drum. The drum extends from a bottom to a top. The drum has a transition height where the modular belt is fully engaged with the drum. The drum includes a plurality of drive bars. Each drive bar has a drive side parallel to the axis of rotation of the drum. The drive sides extend in length from the transition height to the top of the drum for an ascending conveyor and from the transition height to the bottom of the drum for a descending conveyor. The drive bars are spaced apart around the circumference of the drum.

[0016] The drum includes a plurality of transition members, each transition member having a drive surface, at least a portion of the drive surface of each transition member being angled relative to the axis of rotation of the drum such that over the infeed distance, the circumferential location of the drive surface of each transition member advances through the collapse distance of the corresponding modular belt, and at a transition height of the drum, the circumferential location of each drive surface is aligned with a corresponding circumferential location on the drive side of the corresponding drive bar.

[0017] The spiral conveyor further includes a helical support on the circumference of the drum, the helix angle of the helical support being selected such that the helical support extends 1 / 4 to 2 times the circumference of the drum over the infeed distance.

[0018] In some embodiments, the spiral conveyor includes a plurality of parallel support bars. At least one support bar is disposed between each adjacent pair of drive bars on the circumference of the drum. Each support bar extends from at least the transition height up in the ascending conveyor and down in the descending conveyor. In some embodiments, each support bar extends from a corresponding transition member to an outfeed height of the drum. In some embodiments, the outfeed height is lower than the top of the drum in the ascending conveyor or higher than the bottom of the drum in the descending conveyor. In some embodiments, the inner edge of the modular belt contacts the drive bars and the support bars between the transition height and the outfeed height.

[0019] In some embodiments, the spiral conveyor further includes a modular belt driven on a spiral path around the drum by a plurality of drive bars that engage a plurality of teeth on an inner edge of the modular belt. In some embodiments, each tooth of the plurality of teeth has a drive surface configured to contact a drive side of the drive bar. The drive surfaces may be disposed at an angle of greater than or equal to 1° and less than or equal to 5° relative to a radius of the drum. In some embodiments, the modular belt moves radially inward of the drum and the distance between adjacent teeth decreases over the infeed distance.

[0020] In some embodiments, the invention may be embodied as a spiral conveyor having a drum. The drum has a periphery extending from a bottom to a top. The drum has a transition height adjacent the bottom for an ascending spiral and adjacent the top for a descending spiral. The drum has a plurality of parallel drive bars. Each drive bar has a drive side that extends lengthwise on the drum periphery between the transition height and the top of the drum for an ascending spiral and between the transition height and the bottom of the drum for a descending spiral.

[0021] The drum has a plurality of transition members, each having a drive face having a length around the circumference of the drum, each drive face being circumferentially aligned with a corresponding drive side of the drive bar at a transition height, and at least a portion of each drive face being angled relative to the axis of rotation of the drum such that, over the infeed distance, the circumferential location of the drive face advances by at least the collapse distance of the modular belt.

[0022] The spiral conveyor includes a modular belt configured to advance in a conveying direction along a spiral conveying path around the circumference of the drum, up on the ascending conveyor and down on the descending conveyor. The modular belt has a plurality of teeth spaced along the length of the modular belt on an inner edge. Each tooth of the plurality of teeth is configured to engage a transition member and a drive member bar of the drum. In some embodiments, each tooth of the plurality of teeth has a drive surface configured to contact the drive bar. In some embodiments, the drive surface is disposed at an angle of greater than or equal to 1° and less than or equal to 5° relative to the radius of the drum.

[0023] In some embodiments, the modular belt moves radially inward of the drum and the distance between adjacent teeth decreases over the infeed distance.

[0024] In some embodiments, the spiral conveyor includes a helical support around the circumference of the drum, the helix angle of the helical support being such that the helical support extends from ¼ to 2 times the circumference of the drum over the infeed distance.

[0025] In some embodiments, the spiral conveyor further includes a plurality of parallel support bars. Each support bar is disposed between two drive bars around the circumference of the drum and extends upward from a corresponding transition member on the ascending conveyor and downward from a corresponding transition member on the descending conveyor. In some embodiments, each support bar extends from a corresponding transition member to an outfeed height of the drum. In some embodiments, the inner edges of the modular belts contact the drive bars and the support bars between the transition height and the outfeed height.

[0026] For a better understanding of the nature and objects of the present invention, reference should be made to the following detailed description taken in conjunction with the accompanying drawings. [Brief description of the drawings]

[0027] [Figure 1A] FIG. 1 is a perspective view of a spiral conveyor system configured as an ascending conveyor. [Figure 1B] FIG. 1C is a perspective view of the spiral conveyor system of FIG. [Diagram 2] FIG. 13 is a perspective view of another spiral conveyor configured as a descending spiral. [Figure 3A] 1 is a drum according to an embodiment of the present invention. [Figure 3B] FIG. 3B shows the drive bar, support bar and transition piece of the drum of FIG. 3A separated from the drum. [Figure 3C] FIG. 13 is a detailed view showing the transition piece and a portion of the drive bar and support bar. [Figure 4] FIG. 3B shows the drum of FIG. 3A with a conveyor. [Diagram 5] FIG. 13 is a detailed view of a portion of the conveyor at the infeed section of the drum. [Figure 6A] FIG. 13 is another detailed view showing a portion of the conveyor in the infeed section of the drum. [Figure 6B] FIG. 6B is another detailed view showing the conveyor in a higher infeed section than the conveyor of FIG. 6A. [Figure 6C] FIG. 13 is another detail view showing the conveyor fully engaged with the drum above the transition height. [Figure 7A] FIG. 2 is a top view of a portion of a conveyor according to the present invention with the inner portion collapsed. [Figure 7B] FIG. 7B is a top view of the conveyor section of FIG. 7A, where the conveyor is not collapsed. [Figure 8] FIG. 13 is a side elevation view of an assembly of transition pieces. [Figure 9A] FIG. 2 is a top view of a tooth of a belt module showing the drive face angle. [Figure 9B] FIG. 9B is a top view of the tooth of FIG. 9A, showing the tooth width. [Figure 10A] FIG. 2 is a top schematic view of the drum portion and belt at the outfeed of the conveyor belt. [Figure 10B] FIG. 13 is another top schematic view of the drum portion at the outfeed. [Figure 11] FIG. 13 is a side elevational view of a portion of a drum according to another embodiment of the present invention. [Figure 12] FIG. 11 is a side elevational view of a portion of a drum according to another embodiment of the present invention. [Figure 13] FIG. 13 is a top view of the drum of FIG. 12. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0028] In a first aspect, the invention may be embodied as a spiral conveyor 100 having a rotating cylindrical drum 110 (see, for example, FIG. 3A). The drum 110 is rotatable about a vertical axis of rotation a and extends from a bottom 112 to a top 114. The drum may rotate in either a clockwise or counterclockwise direction (as viewed from above the drum). The drum may be configured to drive a conveyor belt along a helical (i.e., spiral) path such that the belt moves upwards, as in the configuration shown in FIGS. 1A and 1B (the "up" conveyor), or may be configured to drive the conveyor belt downwards, as in the configuration shown in FIG. 2 (the "down" conveyor). The up conveyor may be arranged to rotate clockwise or counterclockwise. Similarly, the down conveyor may be arranged to rotate clockwise or counterclockwise. For clarity and convenience, unless otherwise specified, embodiments of the invention will be described with reference to a clockwise up conveyor. This is not intended to be limiting, and the concepts described may be used with conveyor systems having counterclockwise and / or descending configurations.

[0029] The axis of rotation is a geometric imaginary axis of rotation, a geometric intermediate axis that passes through the center of each of the (imaginary) upper and lower circular regions of the drum and extends over the entire height of the drum. For example, the axis of rotation (or axis of rotation a) may not be a mechanical part or element if the drum is attached to, supported by, and / or driven by a turntable (e.g., characterized by a circumferential gear rim), a drive disk, or a gear. However, the drum may have an axis of rotation in the form of a mechanical part used to support and / or drive the drum, e.g., having one or more bearings, sprockets, and / or gears attached to one or both ends of the axis of rotation.

[0030] 3B and 6A, the drum has a transition height Ht, above which the conveyor belt is fully engaged by the drum in the ascending conveyor (below which the belt is fully engaged due to the descending spiral). Below the transition height, the belt of the ascending spiral conveyor transitions from a straight configuration as it approaches the drum, to partial engagement as the belt first contacts the drum and begins to collapse, and eventually to full engagement where the belt completely collapses at the transition height.

[0031] A plurality of drive bars 120 define an outer cylindrical circumference of the drum 110. Each drive bar 120 of the plurality of drive bars has a drive side 122 that is parallel to the axis of rotation a (shown in FIG. 1B). The drive bars 120 are arranged to form a cylinder. Each drive bar is spaced apart from an adjacent drive bar on the circumference of the drum 110. The drive side of the plurality of drive bars has a length that extends from the transition height Ht (for an ascending spiral) to the top of the drum or from the transition height to the bottom of the drum (for a descending spiral).

[0032] The drum may engage with the modular conveyor belt by the drive bars engaging with the teeth of the modular belt. The teeth of the modular belt may extend inward (radially) from the edge of the belt. The drum engages with the conveyor belt by the drive side of each drive bar engaging with the teeth of the belt, for example by pressing against the teeth. The modular belt is made up of individual belt modules, with adjacent belt modules connected to each other. In radial or spiral (modular) conveyor belts, the interconnection of the belt modules is such that the belt modules can rotate relatively at least to some extent in the direction of belt travel. For example, adjacent belt modules may be connected by intercalating link ends, which are connected by pivot rods extending through slots in the link ends, which allow the pivot rods to move to some extent in and against the direction of belt travel, thereby forming a somewhat flexible connection, i.e., allowing the belt modules to move relative to each other.

[0033] In some embodiments, the spiral conveyor does not include a corresponding modular belt. In other embodiments (such as, for example, the embodiment of FIG. 4), the spiral conveyor includes a modular belt having a plurality of teeth configured to engage the drive bar (i.e., the drive surface of the drive bar). With reference to FIGS. 5 and 6A, the drum 210 and corresponding modular belt 290 are configured such that the belt teeth 292 are spaced apart from one another by Z, such that there is a tooth every two or more belt modules, i.e., every fourth module, when Z=4, for example. For example, the spacing may be configured such that the belt has a tooth every third module, every twelfth module, or any integer value in between (i.e., 3≦Z≦12). In some embodiments, Z is selected to be a value between 2 and 20 modules (2≦Z≦20). In one example, when Z=2, the conveyor belt includes a tooth every second module, i.e., each module with teeth is separated from an adjacent module with teeth by a module without teeth. In some embodiments, the teeth are spaced apart by 5-15 belt modules.

[0034] Conveyor belts having spacing between toothed modules (i.e., Z>2) advantageously allow the belt to be manufactured from modules having the same or different pitches. For example, belt modules may be selected to provide tooth spacing that matches a given drive bar spacing. Among many advantages, this allows the conveyor belt to be configured for retrofitting to an existing drum configuration. For example, the radius of an existing drum and the number of drive bars may be known. Based on this information (and optionally other considerations, such as helical gradient, belt width, etc., as described below), a configuration of conveyor belt modules, including tooth spacing, may be selected. Conveyor belts may be configured using belt modules of the same or different pitches to match or closely match the designed drive bar spacing. In an illustrative example, for a given drum having a configuration with 57 drive bars, a suitable configuration of belt modules may have a tooth every seventh module, with six of the modules having a collapsed pitch of 30.9 mm and one of the modules having a collapsed pitch of 35 mm. Alternatively, the same drum may be configured with 30 drive bars and the belt may be configured with teeth every 12 modules, with 2 of the modules having a collapsed pitch of 30.9 mm pitch, 8 of the modules having a collapsed pitch of 35 mm pitch, and 2 of the modules having a collapsed pitch of 38.5 mm pitch. It should be noted that these values ​​are only intended to illustrate the concept of tooth spacing using various belt modules and rounded values. In this manner, if each tooth of the modular belt is spaced by two or more belt modules (i.e., Z>2), at least one module of the two or more belt modules may have a different pitch than the pitch of at least one other belt module of the two or more belt modules.

[0035] The ability to design conveyor belts with custom tooth spacing to use existing drums is advantageous because problematic friction-based spiral systems can be retrofitted as direct drive systems using existing drums, dramatically reducing the cost and time required to convert a system.

[0036] Each tooth 292 of the plurality of teeth may have a drive surface 294 configured to contact the drive side 222 of the drive bar 220 (see, e.g., FIGS. 6A-6C). In some embodiments, the drive surface 294 is disposed at an angle γ relative to the radial direction of the drum. In some embodiments, γ is selected to be greater than or equal to 2° and less than or equal to 5° (see, e.g., FIG. 9A). In some embodiments, γ is selected to be greater than or equal to 0° and less than or equal to 15°.

[0037] The drive bars of the drum are configured to directly engage the modular conveyor belt elements so as to advance the conveyor belt by the drive bars pushing against the modular belt elements, thereby providing a positive drive (e.g., substantially no slippage) rather than a friction drive (overdrive).

[0038] The drum 110 has a plurality of transition members 130. Each transition member 130 of the plurality of transition members includes a drive surface 132. Each transition member 130 is disposed on the circumference of the drum 110. At least a portion of the drive surface 132 of each transition member 130 is disposed at an angle α with respect to the axis of rotation (see, for example, FIG. 3C). The angle is measured with respect to a normal axis in the tangential plane of the drum. At least a portion of the drive surface 132 of each transition member 130 is configured to engage with teeth of a modular belt, which may cause a section of the belt proximate the transition member to advance at a speed faster than the rotational speed of the drum, thereby causing a local module of the belt to collapse. The angle α of at least a portion of each drive surface 132 is configured such that the circumferential location of the drive surface advances an infeed distance i (the vertical distance from the entry height to the transition height of the conveyor belt) by the "collapse distance" of the corresponding modular belt. For example, in some embodiments, α is between 1° and 45°. 7A and 7B, the collapse distance is the difference between the distance Lstr between adjacent teeth of the modular belt in the expanded (tensioned) state and the distance Lcoll between adjacent teeth in the contracted state. In this way, each transition member is able to collapse (a localized portion of) the belt for at least a portion of the in-feed distance.

[0039] 6A-6C show the behavior of the belt on the infeed distance of the drum in an exemplary embodiment of the invention. In FIG. 6A, the belt is seen to be at or near the entry height (where the belt enters the spiral system). It can be seen that the belt is not collapsed (e.g., distance remains between at least some of the belt modules) and that the teeth 292 of a particular belt module are located generally in front of the drive surface 232 of the transition member 230. At this stage, the belt continues to collapse on itself as it begins to follow the curvature of the drum. FIG. 6B shows that the belt is generally completely collapsed, but has small irregularities or other inconsistencies in its configuration (e.g., portions where modules are at mismatched angles with other modules because they are not collapsed evenly with other portions along the belt width). At this stage, the teeth of the local belt module begin to engage the drive surface of the corresponding transition member, for example, at the portion of the drive surface that is at an angle α with respect to the axis of rotation of the drum. 6C shows the belt at the transition height (Ht), where the teeth have moved from the drive face of the transition member 230 to the drive side 222 of the drive bar 220. In the illustrated embodiment, a portion of each drive bar (i.e., starting at the transition height) is integral with the corresponding transition member. At this stage, the belt has completely collapsed and is in a generally regular curved pattern around the circumference of the drum, which allows the belt to provide a smoother, more predictable motion over the remaining height of the drum.

[0040] In some embodiments, the minimum values ​​for the transition piece configuration may be determined mathematically. For example, with reference to Figures 7A-9B, where Lcoll is the distance between adjacent teeth of the collapsed belt, Lstr is the distance between adjacent teeth of the stretched belt, Wt is the width of each tooth, Fsafe is the entry cam safety factor, and Tsafe is the tooth gap safety factor, then: Xecmin=Lstr-Lcoll+Fsafe (1) Cmin = Wt + Tsafe (2) Yecmin=Lstr+Esafe (3) Xecmin is the minimum distance of the entry cams, Cmin is the minimum distance in teeth between two entry cams, and Yecmin is the minimum distance between the lower entry cams.

[0041] Over the infeed distance, the conveyor belt may move radially inward while the modules collapse (i.e., the distance between the teeth decreases). In some embodiments, the transition members and / or drive bars may be tapered over at least a portion of their respective heights, e.g., angled radially relative to the vertical axis such that the diameter of the drum changes over the height. FIG. 11 is a partial view of an embodiment of a drum 300 in which a portion of the transition member 330 tapers at an angle such that the diameter of the drum is wider at the bottom of the drum than at the transition height. In an embodiment of a drum 400, partially depicted in FIGS. 12 and 13, the transition member 430, or a portion of the transition member, is tapered such that the drum is wider at the bottom (diameter db at the bottom of the drum > diameter dh at the drive height) until just above the normal position of the transition height. In other embodiments, the transition members and drive bars are not tapered over their respective heights.

[0042] The transition members 130 and drive bars 120 are configured such that the circumferential location of each drive surface 132 of the plurality of transition members 130 lines up with the circumferential location of the corresponding drive side 122 of the drive bar 120 at the transition height. In this manner, the teeth transition to be driven by the drive bar when the conveyor belt is fully engaged with the drum. It should be noted that the interface 136 between the drive surface 132 and the corresponding drive side 122 may be smoothed by chamfering the interface, radiusing, or similar relief at the interface. Embodiments having such smoothed interfaces should also be considered within the scope of the present invention. For example, a transition member having a chamfered interface with a corresponding drive bar would be considered to have an angle over at least a portion of the infeed distance (even though the portion of the transition member over the infeed distance is chamfered).

[0043] It should be noted that the drive bar and its corresponding transition member may be an integrated part, e.g., made from a single piece and joined (e.g., by welding, brazing, etc.) into a single piece, or may otherwise constitute an integrated part. In some embodiments, the drive bar and its corresponding transition member may be made from separate pieces that interface at the transition height. In some embodiments, the drive bar and its corresponding transition member may be made from two or more separate components that interface at a location other than the transition height.

[0044] Some embodiments of the spiral conveyor 200 include a spiral support 240 around the circumference of the drum (see, e.g., FIG. 4). The spiral support 240 is configured to support the conveyor belt across the drum 210. The spiral support 240 has a twist angle β that is configured such that the belt travels a particular circumferential distance over a given height. The spiral conveyor may be configured such that the conveyor belt makes a quarter to half revolution (i.e., 90° to 720°) around the drum over the infeed distance. In some embodiments, the conveyor may be configured such that the corresponding belt travels 200°, 210°, 220°, 230°, 240°, 250°, 260°, 270°, 280°, 290°, 300°, 330°, 360°, 390°, 420°, 450°, 480°, 510°, 540°, 570°, 600°, 630°, 660°, or 690° or more of the circumference of the drum over the in-feed distance. In some embodiments, the conveyor is configured such that the belt travels between 260° and 270° of the circumference of the drum over the in-feed distance.

[0045] The spiral conveyor 100 may further include a plurality of support bars 140. The support bars 140 may be arranged in parallel on the circumference of the drum 110. The support bars 140 may be spaced apart between the drive bars 120. For example, each support bar may be arranged between two drive bars, with the drive bars and support bars alternating on the circumference of the drum. In other embodiments, the ratio of support bars to drive bars may not be 1:1. For example, two (or more) support bars may be arranged between adjacent drive bars. Each support bar 140 has a length that extends at least above (in the case of an ascending conveyor) or below (in the case of a descending conveyor) the transition height. In some embodiments, each support bar extends above or below (as applicable) a corresponding transition member.

[0046] Each support bar 140 forms part of the peripheral structure of the drum and has a belt bearing surface 142 that is directed radially outwardly away from the drum axis of rotation, thereby contacting and supporting the edge of the modular conveyor belt. The belt bearing surface may form part of the outermost surface of the drum. The support bars can have different cross-sectional shapes, for example rectangular or rod-shaped. The length of the support bar (length along the longest or longitudinal axis) is several times its width or diameter, for example the ratio of length:width or length:diameter is between 5:1 and 100:1. In some embodiments the ratio is between 10:1 and 100:1. In some embodiments the ratio is between 10:1 and 25:1. The width or diameter of the support bar may range from 30 mm to 150 mm, but may be smaller or larger than these widths. The length of the support bar may be up to 8 m or more, depending on the height of the drum. The support bar may have one or more edges that do not function as part of the belt bearing surface, for example chamfered edges, radiused edges, etc. The shape of the support bar may be the same as or different from the shape of the drive bar.

[0047] In some embodiments, the support bar 140 extends to an outfeed height, Ho, of the drum 110. The outfeed height is the height at which the conveyor belt begins to leave the drum. In other words, the outfeed height is the height at which the belt moves from full engagement to partial engagement of the drum. For example, the outfeed height may be lower than the top of the drum (e.g., the top of the drive bar) on the upward spiral and higher than the bottom of the drum (e.g., the bottom of the drive bar) on the downward spiral. In some embodiments, the outfeed height is lower than the top of the drum on the upward conveyor (higher than the bottom of the drum on the downward conveyor). Thus, the support bar does not extend as far as the drive bar. The support bar ends at the outfeed height, allowing the teeth of the conveyor belt to pass over both ends of the support bar on the upward conveyor (or below the downward conveyor) (see, for example, Figures 10A-10B). In Figure 10A, the direction of movement is indicated by arrow T. Over the distance between the transition height and the outfeed height, the inner end of the modular belt may be supported by the drive bar and the support bar. In some embodiments, the trailing edge of each support bar is notched to allow the teeth of the modular belt to pass without interference from the support bar. Support bar interference may be determined as follows: TIFF2024537349000002.tif2778 where hcorr≦0 indicates no interference and hcorr>0 indicates the need for correction. In the above, RA is the radius of the innermost extension of the belt teeth (points labeled A in the diagram), RB is the radius of the outermost trailing edge of the support bar (points labeled B in the diagram), αB is the angle between points A and B, and b is the belt width. If a correction is indicated (e.g. hcorr is positive), the value of hcorr indicates the height of the correction. In other words, hcorr indicates the amount by which the support bar should be shorter than the drive bar.

[0048] The materials of the drive bars, support bars, transition members, and / or conveyor belt may be the same or different from the materials of the other components. Suitable materials may be metals (e.g., steel, aluminum, etc.), polymers (polyethylene, ultra-high molecular weight (UHMW) polyethylene, polypropylene, polyoxymethylene (POM), polyamide (PA), polytetrafluoroethylene (PTFE), polyethylene terephthalate (PET, polyester), polyurethane, etc.), composites, or other materials. Some suitable materials may be modified to enhance properties that may be beneficial in certain applications. For example, some materials may be infused with wax and / or other lubricants, coated with low friction coatings, or otherwise modified to lower friction losses. This may be beneficial, for example, in a descending spiral configuration, to allow the conveyor belt to utilize gravity to move downward along a downward spiral path. In some embodiments, the materials of some or all components are selected differently to exploit their respective functions. For example, the support bar may be made of a low friction material (e.g., polyethylene with a self-lubricating additive) so that the conveyor belt it supports can move upward (and possibly downward) more easily. In another example, the drive bar may be made of steel for increased durability. In another example, the drive bar may be made of a polymer with the drive side made of steel. In another example, the infeed portion of the spiral conveyor (e.g., transition member and / or part of the drive bar, etc.) may be made of a durable material and the remaining portions of the belt engaging components (e.g., drive bar, support bar, etc.) may be made of a low friction material. In yet another example, the drive bar may have a core made of a first material (e.g., steel) and a cap made of another material (e.g., UHMW polyethylene). Other combinations of materials may be used for the drive bar, support bar, transition member, belt module, or other components of the drum and / or conveyor belt.

[0049] As noted above, in some cases, existing drums may be retrofitted and function as described herein. For example, in drums used in existing friction drive systems, the drum may have a closed sheet of material (e.g., metal) covering the outer periphery. To retrofit such drums, the drive bars and other components (e.g., transition pieces, support bars, etc.) according to the present invention may be attached to the closed metal sheet. For example, the drive bars may be bolted, welded, or otherwise joined to the surface of the metal drum. In other cases, the closed sheet of material may be removed or partially removed to allow for the addition of the components of the drum of the present invention.

[0050] In this disclosure, the terms "conveyor belt," "modular belt," and "modular conveyor belt" are terms that are generally used interchangeably to describe a conveyor belt that is composed of a plurality of interconnected belt modules. Although the present invention has been described with respect to one or more specific embodiments, it will be understood that other embodiments of the present invention can be made without departing from the scope of the present invention.

Claims

1. A rotating cylindrical drum (110, 210, 300, 400) extending from a bottom (112) to a top (114) and having a transition height (Ht) at which a modular belt (290) is fully engaged by said drum, The drum is a drum having a plurality of drive bars (120, 220), each having a drive side (122, 222) parallel to the drum's axis of rotation (a), extending longitudinally from the transition height (Ht) to the top of the drum on an ascending conveyor or from the transition height (Ht) to the bottom of the drum on a descending conveyor, the drive bars (120, 220) being spaced apart around the circumference of the drum; a spiral support (240) around the circumference of the drum; The drum is a plurality of transition members (130, 230, 330, 430), each having a drive surface (132, 232), at least a portion of the drive surface (132, 232) of each transition member being angled (α) with respect to the drum rotation axis (a) such that, over an infeed distance, the circumferential position of the drive surface (132, 232) of each transition member advances by at least a collapse distance of a corresponding modular belt (290); The modular belt (290) has a plurality of teeth (292) spaced along the length of the modular belt (290) at an inner edge; The collapsed distance is the difference between the distance (Lstr) between adjacent teeth (292) of the modular belt (290) in a stretched state and the distance (Lcoll) between adjacent teeth (292) of the modular belt (290) in a fully collapsed state, at the transition height (Ht) of the drum, a circumferential location of each drive surface is aligned with a circumferential location of the drive side (122, 222) of a corresponding drive bar (120, 220); A spiral conveyor (100, 200) wherein the helix angle (β) of the spiral support (240) is such that the spiral support (240) extends from ¼ to 2 times the circumference of the drum over an infeed distance.

2. further comprising a plurality of parallel support bars (140); At least one support bar (140) is disposed around the circumference of the drum between each adjacent pair of drive bars (120, 220); 2. The spiral conveyor (100, 200) of claim 1, wherein each support bar (140) extends upward from at least the transition height (Ht) on the ascending conveyor and extends downward from at least the transition height (Ht) on the descending conveyor.

3. 3. The spiral conveyor (100, 200) of claim 2, wherein each support bar (140) extends from a corresponding transition piece (130, 230, 330, 430) to an outfeed height (Ho) of the drum.

4. 4. The spiral conveyor (100, 200) of claim 1, further comprising a modular belt (290) driven on a spiral path around the drum by the plurality of drive bars (120, 220) engaging a plurality of teeth (292) on an inner edge of the modular belt (290).

5. The modular belt (290) has a plurality of belt modules, 5. The spiral conveyor (100, 200) of claim 4, wherein each tooth (292) of the plurality of teeth (292) is spaced apart by two or more belt modules.

6. 6. The spiral conveyor (100, 200) of claim 5, wherein at least one belt module of the two or more belt modules has a pitch that is different from the pitch of at least one other belt module of the two or more belt modules.

7. 5. The spiral conveyor of claim 4, wherein each tooth of the plurality of teeth has a drive surface configured to contact a drive side of a drive bar.

8. 5. The spiral conveyor (100, 200) of claim 4, wherein over the infeed distance, the modular belt (290) moves radially inward on the drum, decreasing the distance between adjacent teeth (292).

9. 4. The spiral conveyor (100, 200) of any one of claims 1 to 3, wherein at the transition height (Ht), the modular belt (290) is completely collapsed.

10. 5. The spiral conveyor (100, 200) of claim 4, wherein an inner edge of the modular belt (290) contacts the drive bar (120, 220) and the support bar (140) between the transition height (Ht) and the outfeed height (Ho).

11. A drum (110, 210, 300, 400) having an outer periphery extending from a bottom (112) to a top (114) and having a transition height (Ht) near said bottom (112) in an ascending spiral or near said top (114) in a descending spiral, The drum is a drum having a plurality of parallel drive bars (120, 220), each drive bar (120, 220) having a drive side (122, 222) extending lengthwise around the circumference of the drum between the transition height (Ht) and the top of the drum in an ascending spiral, or between the transition height (Ht) and the bottom of the drum in a descending spiral; a modular belt (290) configured to advance upwardly or downwardly in a conveying direction along a spiral conveying path around the periphery of the drum, the modular belt (290) having a plurality of teeth (292) spaced at an inner edge along the length of the modular belt (290); The drum is a plurality of transition members (130, 230, 330, 430), each having a drive surface (132, 232) having a length on the circumference of the drum, each drive surface (132, 232) circumferentially aligned with a corresponding drive side (122, 222) of a drive bar (120, 220) at the transition height (Ht), at least a portion of each drive surface (132, 232) forming an angle (α) with respect to the axis of rotation (a) of the drum such that the circumferential position of the drive surface (132, 232) advances by at least a collapse distance of the modular belt (290) over an infeed distance; The collapsed distance is the difference between the distance (Lstr) between adjacent teeth (292) of the modular belt (290) in a stretched state and the distance (Lcoll) between adjacent teeth (292) of the modular belt (290) in a fully collapsed state, A spiral conveyor (100, 200), wherein each tooth (292) of the plurality of teeth (292) is configured to engage a transition member (130, 230, 330, 430) and a drive bar (120, 220) of the drum.

12. further comprising a helical support (240) around the circumference of said drum; 12. The spiral conveyor of claim 11, wherein the helix angle (β) of the helical support (240) is such that the helical support (240) extends from 1 / 4 to 2 times the circumference of the drum over the infeed distance.

13. 12. The spiral conveyor of claim 11, wherein each tooth (292) of the plurality of teeth (292) has a drive surface (294) configured to contact a drive bar (120, 220).

14. 14. The spiral conveyor of claim 13, wherein each drive surface (294) forms an angle (γ) of between 1° and 5° relative to the corresponding drive side (122, 222) of the drive bar (120, 220).

15. 15. A spiral conveyor as claimed in any one of claims 11 to 14, wherein over the infeed distance, the modular belt (290) moves radially inward on the drum, decreasing the distance between adjacent teeth (292).

16. further comprising a plurality of parallel support bars (140); at least one support bar (140) is disposed around the circumference of said drum between each adjacent pair of drive bars (120, 220); 15. A spiral conveyor according to any one of claims 11 to 14, wherein each support bar (140) extends upward from at least a transition height (Ht) on the ascending conveyor and extends downward from at least a transition height (Ht) on the descending conveyor.

17. 17. The spiral conveyor of claim 16, wherein each support bar (140) extends from a corresponding transition piece (130, 230, 330, 430) to an outfeed height (Ho) of the drum.

18. Spiral conveyor according to any one of claims 11 to 14, wherein at the transition height (Ht) the modular belt (290) is completely collapsed.

19. 18. The spiral conveyor of claim 17, wherein an inner edge of the modular belt (290) contacts the drive bar (120, 220) and the support bar (140) between the transition height (Ht) and the outfeed height (Ho).

20. The modular belt (290) has a plurality of belt modules, 15. The spiral conveyor of any one of claims 11 to 14, wherein each tooth (292) of the plurality of teeth (292) is spaced apart by two or more belt modules.

21. 21. The spiral conveyor of claim 20, wherein at least one belt module of the two or more belt modules has a pitch that is different from the pitch of at least one other belt module of the two or more belt modules.

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