Positive-drive spiral conveyor and belt

[0001] The invention relates generally to motor-driven conveyors, in particular to screw conveyors, in which the conveyor belt is driven by means of contouring along a spiral path around a rotary drive tower.

[0002] Conveyor belts are often used to convey products, such as food products and other materials, through cooled or heated environments. Screw conveyors in which the conveyor belt travels along a spiral path curling around a central tower, drum or cage are used in freezers and ovens to provide a long, space-saving conveyor path.

[0003] Some screw conveyors are constructed with a spiral path supported on a central, non-rotating tower. The conveyor belt is driven around the spiral path by means of chain drive wheels in one place outside the spiral path. The maximum tension in the belt that occurs just before it is coupled to the chain drive wheels can be quite large for such a long belt. In order to reduce the maximum belt tension, assisted screw conveyor systems are used. In these assisted systems, the conveyor belt is driven by frictional contact between the inner edge of the belt and the faster rotating outer surface of the rotary drum around which the belt is spirally wound. Since the belt is driven along the entire spiral path, the maximum belt tension is reduced. However, some tension is still needed for effective frictional engagement between the drum and the belt edge. In addition, coupling

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Friction causes wear to the edges of the belt and the outer surfaces of the drum. Because a large portion of the rotational energy needed to drive the drum is lost to friction, the engine and power requirements can be quite high. And, because the assisted systems are sensitive to friction between the outer surface of the drum and the inner edge of the belt, the correct tension and reinforcement settings vary between installations.

[0004] Propeller-driven screw systems, in which the drive structure on the outside of the rotating cage engages with the structure on the inside of the conveyor belt, are used to overcome some of the disadvantages of assisted systems.

Because there is a shape coupling between the regularly spaced drive structure on the cage and the regularly spaced edge structure on the inside edge of the belt, there is no slippage as in assisted systems. No additional tension is needed and friction losses are reduced. But one of the problems associated with propeller-driven screw systems is clean coupling and detaching of the belt from the drive structure on the cage.

[0005] US 5,310,045 discloses a low tension helical conveyor belt system comprising a conveyor belt and a screw conveyor in accordance with the preamble of claims 1 and 8. Drive assistance is provided between the drive cage or drive shaft and the plastic conveyor belt by ridges formed essentially vertically on rods or caps on rods of the cage. These ridges interact with the grooves located in the inner edge elements of the tape or with gaps between successive

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EP 2 593 385 B1 with edge elements.

[0006] As claimed in the first aspect, a conveyor belt is provided, 1.

of the present invention as illustrated in [0007] In an additional aspect, a helical conveyor is provided, claim 8.

of the present invention as illustrated in [0008] One version of the conveyor belt having the features of the invention includes a series of rows of belt modules, interconnected between successive rows along hinge joints defining hinge axes extending perpendicular to the direction of conveyance from the first side edge of the rows to the opposite second edge side rows. The hinged joints have slack in the transfer direction to allow the rows to fold together on the first side edge when the first side edge is on the inside of the transfer path bend. The first side edge has a driving surface. Teeth protrude outwards from the first edges of the lateral rows to the distal ends. The guiding surface on each tooth is oriented so that it guides the end of the outer drive element between the teeth so that the drive element is in contact with the drive surface of the next row to drive the conveyor belt in the transfer direction.

[0009] In another aspect of the present invention, one version of the screw conveyor comprises a rotatable cylindrical drive tower that has an outer periphery extending from the bottom up. The tape entry level is near the bottom for the upward spiral or near the top for the downward spiral. Parallel drive members extend along the length around the perimeter of the tower

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EP 2 593 385 B1. Each has a ridge protruding radially outward from the lower end to the upper end. The lower ends of the ridges are indented a first distance upwards from the entry level of the tape for the upward spiral, or the upper ends of the ridges are indented a first distance down from the entry level of the tape for the downward spiral. The conveyor belt moves up or down in the conveying direction along the helical conveying path around the outer periphery of the rotary cylindrical drive tower. The conveyor belt comprises a plurality of rows of belt modules having an upper side and a bottom side and articulated to each other between successive rows along articulated joints defining hinged axes extending perpendicular to the direction of conveyance from the first side edge of the rows to the opposite second side edge of the rows. The hinged joints have slack in the transfer direction to allow the rows to fold together on the first side edge when the first side edge is on the inside of the spiral transfer path. The first lateral edge of each row includes a drive surface and a series of outwardly extending teeth with guide surfaces oriented so as to guide the lower ends of the ridges in an upward spiral or the upper ends of the ridges in a downwardly spiral between teeth, so that these ridges are arranged in drive contact with the drive surfaces to drive the conveyor belt in the conveying direction along a helical conveying path.

[0010] In another version, the screw conveyor comprises a drive tower that extends from the bottom up and rotates about a vertical axis. The parallel drive members extend longitudinally from the bottom to the top of the drive tower. Each of the driving elements has a ridge protruding outwards,

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EP 2 593 385 B1 whose distance from the vertical axis varies from the bottom up the drive tower. The conveyor belt is driven by contouring on a spiral path around the drive tower by the crests of the drive elements engaging the inner edge of the belt.

BRIEF DESCRIPTION OF THE DRAWINGS [0011] These features of the invention, as well as its advantages, will be better understood with reference to the following description, attached claims and accompanying drawings, in which:

FIG. 1 is a schematic side view of a screw conveyor system with the features of the invention;

FIGURES 2A and 2B are profile and main views of the lower segment of the driving tower drive members of FIG. 1; and FIG. 2C shows a top view of the screw conveyor belt entering the lower segment of the drive tower drive members of FIG. 1;

FIGURES 3A and 3B are profile and main views of the intermediate segment of the driving tower drive members of FIG. 1; and

FIGURES 4A and 4B show views from the profile and from the front of the upper segment of the driving elements of the drive tower of FIG. 1;

FIGURES 5A and 5B are axonometric views from above and below of the inner edge of the side-bent conveyor belt module having the features of the invention;

FIG. 6 is an axonometric view of the inner edge of another version of the side-bent conveyor belt module having the features of the invention;

FIG. 7 is an axonometric view of the inner edge of yet another version of the side-bent conveyor belt module having the features of the invention;

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FIG. 8 is an axonometric view of the inner edge of yet another version of the side-bent conveyor belt module having the features of the invention;

FIG. 9 is a top view of the inner edge of another version of the laterally bent conveyor belt and the periphery of the drive tower having the features of the invention;

FIG. 10 is an axonometric view of a portion of the inner edge of the conveyor belt constructed of the modules of FIGURES 5A and 5B;

FIG. 11 is a side view of another helical conveyor that uses a modular conveyor belt as in FIGURES 5-8;

Fig. 12 is an oblique view of a portion of the screw conveyor drive member shown in FIG. 11;

FIG. 13 is a cross-sectional view of the drive element of FIG. 12, taken along lines 13-13;

FIG. 14 is a side view of a portion of the screw conveyor of FIG. 11, which shows the drive tower at the belt entry level;

FIG. 15 is an enlarged view at the entry level of the screw conveyor belt of FIG. 11, which shows the initial coupling of the conveyor belt to the drive means;

FIG. 16 is a side view, superimposed on a force diagram, of a different version of a helical drive tower with spiral drive rods around the perimeter of the tower used with conveyor belts made of modules as in FIGURES 5-8; and

Figures 17 and 18 are oblique views of two other versions of drive towers with outwardly extending bottom aprons used with conveyor belts made of modules as in FIGURES 5625PL00

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8.

DETAILED DESCRIPTION [0012] The screw conveyor is shown schematically in FIG. 1. The screw conveyor comprises a drive tower 10 in the form of a cylindrical drum or cage, which is driven to rotate about a vertical axis 12. The rotary tower has a plurality of parallel, substantially vertical drive elements 14 arranged at regular intervals around its periphery 16. Each element propulsion extends longitudinally between the lower 18 and upper 19 parts of the tower. The conveyor belt 20 runs along a multi-level spiral path around the tower. This path is defined by a spiral guide or by the guide at the bottom and stacking plates mounted on the belt. The inner edge of the belt is form-coupled to drive elements that drive the belt up the tower as it rotates. The belt travels around various lifting, passive and feeding wheels of the chain link 22 during its course from the exit at the top of the tower back to the entrance at the bottom. The tower 10 is mounted in its lower part to the base 24 and is rotated by means of a motor and gears (not shown).

[0013] Each of the drive members 14 comprises a substantially vertical rail 26, which is attached in the lower part 18 to the lower ring 27 of the drive tower 10, and a ridge 28 that projects out of this rail, as shown in FIGURES 2A and 2B. Shown is the ridge formed on the cap 32 that covers the outer surface 34 of the rail along almost its entire length. As shown in FIG. 2C, flaps 36 hold the rail cap. Instead of creating it on the overlay, the ridge could be welded directly to the rail or formed uniformly with it.

[0014] In the bottom segment 38 of each drive element,

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The ridge 28 comprises a constant height area 40 and a tapered area 42. A constant height area begins at the bottom of the rail and extends upward to the conical area. The height of the ridge 28 increases from the height h2 in the area of ​​constant height to the maximum height h1 at the upper end of the converging area. In other words, the distance of the ridge 28 from the vertical axis 12 (FIG. 1) of the drive tower increases from a fixed distance to a greater distance at the upper end of the converging area. The area of ​​constant height of the lower segment 38 is deviated from the vertical at an angle α.

conveyor conveyor [0015] The deviation from the vertical orientation and the small height h2 of the ridge at the bottom of the lower segment of the drive tower facilitates climbing conveyor belt 20 onto the rotary tower as shown in FIGURES 2B and 2C. The band 20 is shown as a modular plastic band made of a series of rows of band modules 44 conventionally connected in a row arrangement (not shown) with rows of hinged rods. As the band travels tangentially to the rotary tower 10, one of its inner edges 46 may contact one of the ridges 28. As the belt is directed closer towards the drive tower, the ridge eventually slides off the inner edge and enters a gap of 48 between adjacent rows of belt. The angular orientation of the ridge in the lower segment helps in bringing the tape into proper engagement as it runs along its inclined spiral path 50. Before the belt reaches the converging area 42 of the lower drive segment 38, the ridge assumes a position just before (in the running direction) the inner edge of the belt row. In this position, the driving element is coupled to the inner edge of the belt for driving it by contouring along a spiral path 50 without slipping. In convergent area 42, the height of the ridge gradually increases

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Up to its maximum height h1. This gradual increase further helps in transferring the belt to full form engagement with the rotary tower as indicated by the maximum height 14 'drive element.

[0016] The ridge 28 extends outward to a maximum height h1 in the intermediate segment 52 of each drive member 14. In this intermediate segment, the distance of the ridge from the vertical axis 12 (FIG. 1) is constant. The intermediate segment is located on the perimeter of the drive tower just above the bottom segment 38, as shown in FIGURES 3A and 3B. The intermediate segment makes up the greater part of the tower height and, consequently, provides the majority of drive coupling to the conveyor belt. The intermediate segment may be vertical as shown or offset from vertical. Just before the strip exits the upper part 19 of the tower 10, the ridge height narrows from the maximum height h1 to zero in the upper part, as shown in FIGURES 4A and 4B. This narrowing occurs in the upper segment 54 of each drive element 14. The upper part of each rail is attached to the upper edge 56. The decreasing height of ridge 28 or its distance from the vertical axis of the drive tower in the upper segment allows gradual and smooth detachment of the belt from the driving elements of the rotary tower.

[0017] Thus, the screw conveyor of FIGURES 1-4 drives the conveyor belt by means of shape coupling without assistance along a spiral path by means of driving elements which engage with the inner edge of the belt by means of a ridge which changes its height from the bottom upwards rotating propeller tower.

[0018] The belt edge module 60, shown in FIGURES 5A and 5B, can be used to construct a laterally bent conveyor belt with a different edge structure from that of the belt 20 of FIG. 2C. The edge module 60 has tooth 62

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In the shape of a tent attached to the recess 64 in the side edge 66 of the tape. This tooth is pressed into the recess 64 from the upper side 68 of the module. The head of the screw 70 screwed into the corner of the projection 72, extending from the tooth base 74, grips the bottom side 69 of the module on the inside corner of the cavity to attach the tooth to the module. This tooth can be detached from the module by removing the screw. The projection 72 also partially covers the opening of the module pivot rod to help hold the hinge rod within the band. In this version of the edge module, instead, the tooth could be inserted from the bottom side 69 and held in the same way. Thus, these teeth may extend upward from the upper side 68 or downward from the lower side 69. A tent-shaped tooth has a pair of guide surfaces 78, 79 that converge at a distance from the distal end 80 of the tooth.

[0019] In FIG. 6 shows another version of a tooth extending from the inner edge of the tape module. In this module, prism-shaped tooth 82 with a diamond in the base extends radially outward from the inner edge 84 of module 86. The diamond-shaped tooth is integrally formed with the module and has four guide surfaces 88A-D and two vertical drive surfaces 89A, 89B . It should be obvious that the tent-shaped tooth 62 of FIGURES 5A and 5B could be integrally formed with the edge module, and the diamond-shaped tooth of FIG. 6 could be made as a separate element that can be attached to the module. Another tape module with an integrally formed tooth is shown in FIG. The tape module 130 has a prism-shaped tooth 132 with a truncated triangle in the base protruding radially outwardly from the inner edge 134 of the module. The guide surfaces 136, 137 converge from the upper and lower surfaces of the module. The base of the triangular prism acts as

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Drive surface 138. The belt module 140 of FIG. 8 contains tooth 142 in the form of a cylindrical oval. This tooth has rounded guide surfaces 145, 146 with opposing driving surfaces 146, 147 lying between them.

[0020] Part of a conveyor belt 90 made of modules having an inner edge as in FIGURES 5A and 5B, is shown in FIG. 10. This part of the belt represents the modules connected to each other in rows 92 by means of hinge rods 93 in articulated joints 94 extending perpendicular to the direction of conveyance 96. The belt pitch is the distance between successive hinges. The holes 98 for the hinge rods are elongated in the conveying direction, so as to provide sufficient play in the conveying direction, so that the side edge 100 of the tape collapses on the inside of the bend, while the opposite outer edge widens so as to follow its longer path on outer radius. Because the belt 90 may have low tension when climbing the helical drive tower, the rows may fold together as shown in FIG. 10 The rear guide surfaces 79 of the teeth 62 deflect from their distal ends 80 towards the drive surfaces 102 facing the successive rear modules 102. The front guide surfaces 78 of the teeth 62 deflect from their distal ends 80 in the opposite direction to the rear facing surfaces 102 on the subsequent front modules. Opposite surfaces 103 at the edges of the belt can be used as driving surfaces if the belt is operating in the opposite direction.

[0021] The helical drive tower 104 is shown in FIG. 11 with a conveyor belt 90 following a spiral path 106 around the periphery of the tower. The vertical drive elements 112 extend from the top 114 to the bottom 115

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EP 2 593 385 B1 parts of the tower. The drive elements are preferably positioned at intervals equal to the total multiple of the belt pitch in the target obtain optimal operating characteristics. But they can also be spaced at intervals with incomplete tape divisions or unevenly at different integer divisions of the tape pitch. The ridges 116 protrude radially out of the spaced apart drive elements 112 from the top ends 118 of the ridges to the bottom ends 119. In this example, the conveyor is an upward spiral rotating in direction 108 with a spiraling ascending direction 110. Initially, the belt engages with the tower at the entry level 120 of the tape, which is located below the lower ends of 119 ridges. The tape runs around the tower on a slightly inclined path for about 90 ° or similar, or on a circumferential arc of any length necessary to assemble the inner edge of the tape, before rising to the level of the lower ends 119 ridges 116.

[0022] As shown in FIGURES 12 and 13, the lower end 119 of the ridge 116 is tapered. The drive element 112 is a flat belt with a ridge protruding outward along most of its length. The grooves 121 in opposite edges of the belt enter the edges of the peripheral structure 122 forming the perimeter of the tower.

[0023] The coupling of the conveyor belt with the rising spiral is shown in FIGURES 14 and 15. FIG. 14 shows the bottom row of conveyor belt engaging the tower below the bottom ends 119 of ridges 116. The bottom ends of the ridges are offset vertical distance 124 above belt entry level 120. In this offset part of the tower, the inner edge of the tape runs along the tower in frictional contact with the periphery of the tower to allow the inner edge of the tape to fold. Finally tape 90

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EP 2 593 385 B1 rises to the lower ends 119 of the ridges 116. The distal end 119 of the ridge 116 first contacts the tooth 62 extending upwards from the upper side 68 of one of the rows of tape in one of three places: (a) the front guide surface 78 ; (b) a rear guide surface 79; or (c) distal end 80. If the initial contact is on the front guide surface 78, the lower end 119 of the ridge tends to fall down the front guide surface and push the rear row away from the front row so that the ridge fits between the rows in position to drive the front row by contouring. If the lower end 119 of the ridge 116 first contacts the rear guide surface 79, the lower end slides down the surface leading to the gap between the row and the next rear row to a position enabling the front side 126 of the ridge 126 to exert motive force on the surface drive 102 (FIG. 10) of this row. If the lower end of the ridge initially contacts the upper distal end 80 of tooth 62, then the ridge may slide down on each guide surface, depending on the friction and any tension of the belt.

[0024] In a downward spiral, this operation is analogous. The tape entry level is above the tops of the ridges at the top of the tower. These ridges are indented below the entry level by a vertical distance sufficient to allow the inner edge of the tape to fold around the perimeter of the tower. The teeth for the tape in the downward spiral extend down from the bottom of the tape to engage the upper ends of the ridges. A belt conveyor constructed of modules as in FIG. 6 with guide surfaces 88A-D pointing both up and down, and drive surfaces 89A, 89B or, as in FIG. 8, with fillets and bottom guide surfaces

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145 and 144 and driving surfaces 146, 147 can be used in both downward and upward spirals and driven in both directions. The teeth in FIGURES 6 and 8 are symmetrical around their vertical and horizontal center lines. The two guide surfaces 136 and 137 of the triangular tooth 132 in the module of FIG. 7 enable the conveyor belt composed of such modules to be driven on its drive surface 147 in each upward or downward spiral.

[0025] Figure 9 shows a sideways curved conveyor belt with edge modules 150 that have a plurality of teeth extending radially outward from each row. Each of the teeth 152, 153 has a front, angled guide surface 154 and a rear drive surface 156 forming the shape of the saw teeth. Each drive member 158 on the periphery of the drive tower has a plurality of saw-shaped ridges 160 with front drive sides 162. The guide surfaces 154 guide the front driving sides 162 of the ridges into contact with the front drive surface 156. The ridges on the tower are slightly thinner than the teeth on the belt, so that they more easily fit together. And higher tooth density provides a drive tower with more coupling points available.

[0026] Although the drive members on the periphery of the drive tower shown in FIGURES 1-4 and in the drive tower shown in FIGURES 11-15 are generally vertical, these drive members can be tilted from the vertical as shown in FIG. 16. Propulsion tower 166 has ridges 168 on its propulsion elements tilted from the perpendicular at perimeter 170 of the tower to form a spiral arrangement. The conveyor belt 172 is shown in a state of operation as a spiral downward along the spiral path 174. This tape is made of edge modules having

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Keep pointing

Eliminates teeth as in FIG. 7, i.e. teeth with an inclined surface for the direction of conveying, preferably at the same angle as the deviation of the driving ridges from the vertical. Lower guide surface 136 leads the upper end 176 of the drive members to initial contact with the edge of the belt. The front edges of the ridge 178 engage the upper guide surfaces of the 137 edge modules, which act instead of the drive surfaces. The force plot superimposed on the tower of FIG. 16 shows that the total force FT exerted by the front side 178 of the oblique ridge 168 on the similarly oblique tooth surface 137 (shown enlarged) and acting in a direction perpendicular to this surface has a vertical component Fv that helps the inner edge of the conveyor belt.

this requires the additional holding structure that would be needed if the conveyor belt steps onto the propeller tower with vertical drive elements as in previous versions. And, in the case of the forward-tilted ridges of FIG. 16, the conveyor belt would move faster than the rotation of the drive tower. If the ridges were inclined the opposite way, the tape would move more slowly.

[0027] Two other versions of the drive towers are shown in

FIGURES 17 and 18. The drive tower 180 in FIG. 17 has a cylindrical upper portion 182 and an apron portion 184 that tapers outwardly from the vertical axis axis 186 of the tower towards the lower portion 188 of the tower. The drive tower 190 in FIG. 18 has an upper part 192 with a first diameter d1. Apron portion 194 includes a bottom portion 196 having a second diameter d2 that is larger than the first diameter d1 of the upper portion 192. A tapered portion 197 connects the lower portion 196 to the upper portion 192. (The drawings exaggerated the degree of convergence). Belt conveyor entering each of the drive towers from

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The apron from below has a certain amount of initial stress on the outer edge of the belt. When the inner edge of the conveyor belt begins to fold during its spiral upward motion towards the apron part of the tower, the diameter of the tower slightly decreases in the apron part to reduce the stress on the outer edge of the conveyor belt.

[0028] Thus, the screw conveyors of FIGURES 11-18 drive the conveyor belt by means of shape coupling without assistance along a spiral path by means of driving elements which engage with the inner edge of the belt by means of a ridge which is initially brought into the driving position on drive surface on the belt. And the screw conveyor system also allows the use of belts whose internal turning radius does not match the radius of the drive tower.

Laitram, LLC

Proxy:

76P35625PL00

EP 2 593 385 B1