Conveyor for a treatment unit

Abstract: The injection-moulded links of an endless conveyor belt (4), especially designed for moving products through a treatment unit, comprise a number of flat link portions (8) with recesses (10) defined by pulling arms (9), said link portions (8) having slits (12) and said recesses (10) being adapted to receive link portions of an adjacent link so that a pivoting pin (7) passing through the pulling arms and the slits can connect both link portions. Prefer­ ably at least one semi-circular end wall of the slits of the uttermost link portions is at an angle that corresponds to the curvature radius of the drums of the conveyor wherein the conveyor belt is to be mounted.

Description: The invention relates to a treatment unit as defined in the preamble of claim 1. Known units of the type as referred to above, which are i.a. known as cooling towers for bakery products, employ metal strip conveyor belts which are mounted on conveyor chains. A conveyor belt for use in a treatment unit as defined in the opening paragraph is disclosed in GB-A-1.359.185. This known conveyor belt comprises a series of parallel transverse rods, and a plurality of open-work belt sections extending between and pivoted to the transverse rods, each belt section being of cranked or wavy form having a series of longitudinally extending components spaced apart transversely of the belt and joined at their ends by two rows of transversely extending cross components, and adjacent belt sections longitudinally of the conveyor belt intermeshing with one another at the transverse rods. The belt sections of this known conveyor belt are plastics mouldings, their cross components are tubular, and the transverse rods extend through the tubular cross components, wherein the cross components of adjacent belt sections longitudinally of the belt engaging and intermeshing with one another at a common transverse rod. When the conveyor belt is intended to make a curve one row of cross components is made appreciably broader than the other row, that is measured in the lengthwise direction of the conveyor belt, and the apertures in the components are of oblong cross-section elongated in the lengthwise direction of the belt. The invention aims to provide an alternative treatment unit comprising a conveyor belt which is different from the known conveyor belt. To this end the present invention provides a treatment unit according to the opening paragraph comprising the features of the characterizing part of claim 1. In a preferred embodiment the exterior sleeves are connected through bends to the connecting point of a link portion and an outer pulling arm. In a further preferred embodiment the longitudinal wall facing away from the exterior sleeve abuts the opposite exterior sleeve in an interior curve. The link portions preferably comprise grooves at the bottom, extending in the direction of travel of the conveyor belt, which grooves have a depth of more than half the thickness of the link portions, and a length extending up to or near the edge of the link portions which faces away from the pulling arms. This is important with respect to maintaining the conveyor belt and keeping it clean. The invention will be elucidated hereinafter on the basis of the drawing, in which by means of an example an embodiment of a unit according to the invention is represented. In the drawing: fig. 1 shows a top view of the left portion of the treatment unit, fig. 2 shows a top view of the right portion of the treatment unit, fig. 3 shows a longitudinal view of fig. 2, fig. 4 shows, on a larger scale, a top view of a portion of a conveyor belt of the unit of figures 1-3, fig. 5 shows, at about real size, a horizontal cross-section through an outer link portion, fig. 6 shows, at about real size, a vertical cross-section through a link of the conveyor belt of fig. 4, fig. 7 shows a bottom view of fig. 6, fig. 8 shows a longitudinal view of a chain crown for a driving or turning wheel, fig. 9 shows, at a larger scale than in figures 1-3, a schematic top view of a driving and tensioning means, and fig. 10 shows a longitudinal view of fig. 9. The unit represented in figures 1-3 has two freely rotatable drums 1 and 2 with a diameter of 1.6 m of which the vertical centre lines 3 are spaced apart at at least 40 m. A conveyor belt 4 (fig. 4) with a length of approx. 600 m. extends through said unit. The products are supplied to the unit at drum 1 in a low position A. The conveyor belt 4 and the products possibly positioned thereon are then conveyed, while steadily rising, through a lowermost path portion B at the front of the unit, subsequently around the drum 2, and then obliquely through a lowermost path portion C at the rear of the unit so as to arrive at the second floor or level. In this way, the following floors or levels are also passed, in order to finally arrive at the high discharge position D of drum 2. A roll 5 is mounted at position D so as to guide the conveyor belt 4 to a vertical path portion E. At a level below the lowermost path portion B, a subsequent roll 6 is disposed perpendicularly below the roll 5, for guiding the conveyor belt 4 to a path portion F which ends at position A and connects there by means of a roll (not shown) to the lowermost path portion B so as to make the conveyor belt 4 endless. The manner in which the conveyor belt 4 is supported in the various path portions is not relevant to the invention. The unit may also comprise more than two drums or similar guidings and the path of the conveyor belt may also comprise S-shaped track portions. However, the manner in which the conveyor belt itself is devised is essential to the invention and therefore it will be elucidated on the basis of figures 4-7. Fig. 4 shows five links of a conveyor belt 4 comprising pivoting pins 7, in the position in which the central pivoting pin 7 intersects the vertical centre line 3 of the drum 1 in fig. 1. The three links on the left of fig. 4 are therefore arranged in a curve along the drum 1 and the two links on the right are so to speak incorporated in an obliquely rising path portion C. In the represented embodiment, a link consists of six link portions 8 which each comprise two buckled pulling arms 9. Two pulling arms 9 of one link portion 8 define a recess 10 which is wide enough to receive a link portion of an adjacent link with clearance. Therefore the distance between said two pulling arms is slightly greater than the width of a link portion 8. For the sake of strength, the pulling arms 9 of one link portion 8 are connected by a rib 11, connecting the two buckling points of the pulling arms 9 of one link portion 8. Without this provision, the pulling arms might bend and eventually break. Said rib 11 is positioned so close to the link portion 8, that the link portions, comprising a slit 12 for receiving the pivoting pin 7, can sufficiently move back and forth in said recess. As the semi-circular end walls of the slits 12 of the four interior link portions 8 are simply perpendicular to the side walls of said link portions and therefore parallel to the centre lines of the pivoting pins 7 in the straight path portions, the pulling forces in the straight track portions of the conveyor belt are substantially transferred to the pivoting pins 7 by said four link portions 8. The semi-circular end walls of the slits 12 of at least one of the exterior link portions 8 are not perpendicular to the side walls, but they have centre lines which are at such an angle to the centre lines of the pivoting pins 7 that these centre lines intersect at a point which at given times substantially coincides with the vertical centre lines 3 of the drums 1 and 2. This is indicated in fig. 5 by angle α. The consequence of this detail is that the pulling force in the 180° curve portions of the conveyor belt about the drums 1 and 2 is substantially transferred to the uppermost link portion 8 and the pivoting pin 7, both in figure 7. Two adjacent pulling arms 9 of the two neighbouring link portions 8 are connected by a sleeve 13 in which a pivoting pin 7 can be received. The ends of a pivoting pin 7 are fixed into bores of outer sleeves 15 by means of a screw or pin 14, which sleeves are connected via bends 16 to the connecting point of a link portion 8 and an outer pulling arm 9. These bends can either be massive or comprise a hole 17, as shown. This does not only save material, but it also provides a better (cooling) air circulation. The longitudinal wall facing away from the outer sleeve 15 of the bend 16 is positioned so, that it will face the oppositely disposed outer sleeve 15 in the inner curve (left bottom side of fig. 4). In this way pressing forces are compensated, so that the conveyor belt cannot "break out". Connecting two neighbouring link portions 8 by a sleeve 13 has the advantage that the length of the space 18 between the link portions 8, engaging drive wheels 20 driven by motors 37 and resembling chain wheels of a driving and tensioning means 21, can be chosen wider. So as to be able to also use the conveyor belt in oppositely rotating units with e.g. S-curves, it is devised symmetrical, i.e. with semi-circular end walls in either outer link part 8 at an angle α and also having a bend 16 on either end. Grooves 19 are made in the bottom of the link portions 8. It appears from figures 6 and 7 that those grooves 19 have such dimensions that they are connected to a slit 12. Therefore they have a depth of more than half the thickness of the link portion 8 and such a length that the semi-circular side walls of the slits are interrupted, resulting in the set of three visible planes 22 represented in fig. 7. Consequently, the pivoting pins 7 have to remove combinations of crumbs and fat particles deposited thereon only over a shorter path. A further elucidation to the driving and tensioning means 21 will be given on the basis of figures 8-10. Such a means 21 is merely represented in fig. 3 in the lowermost path portion B, but it is standard procedure to also provide the superposed path portions B and also the path portions C of the unit with such a means. Each driving and tensioning means 21 comprises a motor 37 that rotatably drives a shaft 23. Five chain crowns 24, together forming a drive wheel 20, are mounted on said shaft 23. According to fig. 8 such a chain crown 24 comprises a set of eight cavities 25 of which the pitch corresponds to the centre distance of the pivoting pins 7 in a straight path of the conveyor belt, so that blunt teeth 26 disposed between the cavities 25 are able to engage in the spaces 18 of the conveyor belt 4 so as to drive it. A turning wheel 27 with the same exterior as the drive wheel 20 is freely rotatably mounted on a second shaft 28. Further guide means 29 are provided so as to have the conveyor belt 4 follow two horizontal loops, and a tensioning roll 30 which is borne on a shaft 31 which can be slid far into a slit 32 of the frame and which is tensioned by springs 33. The special characteristic of the tensioning and driving means 21 is that a number of small rolls 34 is disposed between the wheels 20 and 27 which project slightly above the path B in order to position the products which have gone off course, such as loaves of bread, again correctly perpendicularly to the direction of travel of the conveyor belt 4. The most favourable position for treatment could be disrupted during the motion of the breads through curves about the vertical drums 1 and 2. The small rolls 34 have such a centre distance that they clean one another even if the smallest bit of dirt adheres to one of them, which is even enhanced by the fact that they are all driven in the same direction by transfer means 35 branched from the motor 37. The number of small rolls 34 has obviously also been chosen so, that the products to be treated cannot tilt. Crumbs and the like are collected in a tray 36 which can be emptied on a regular basis. Within the framework of the claims other embodiments than merely the ones represented in the drawing are also possible, particularly units having more than two drums in which the path can include S-shaped track portions.

Claims: Treatment unit comprising at least two guiding drums (1, 2), each being rotatable about a vertical line (3), an endless conveyor belt (4) provided with links and pivoting pins (7), for moving products along a path through the treatment unit, said path following a curve of a definite grade value in a slightly tilted plane along the guiding drums (1, 2), support members for the remaining, also slightly tilted, path portions, the arrangement being so that the products can be supplied at the one drum (1) in a low position and discharged at the other drum (2) in a high position or vice versa, said conveyor belt (4) returning from the high position to the low position via a vertical and a horizontal path portion, and driving and tensioning means (21) for the conveyor belt (4), said links consisting of a material that can be rolled or obtained by injection moulding of a synthetic material, each link comprising a number of flat link portions (8) with recesses (10) defined by pulling arms (9), each link having a pivoting pin (7) which is able to move in the plane of the conveyor belt (4) through slits (12) of the link portions (8) of an adjacent link disposed in the recesses of the first link, and said driving means (21) comprising at least one drive sprocket wheel (20) of which the teeth (26) are received in the space between two link portions, the adjacent pulling arms (9) of two neighbouring link portions being connected by a sleeve (13), the pivoting pin (7) of each link being received by and tightly secured to all sleeves of this link, at least one end of each pivoting pin (7) being secured in an exterior sleeve (15) connected on its inside to an outer pulling arm (9), the end wall of the slit (12) of at least one of the exterior link portions (8) having a semi-circular wall, characterized in that the end wall of this slit has a centre line making an angle with the centre line of the pivoting pin (7) which it receives such that these centre lines in the curve substantially coincide with the vertical centre line (3) of the respective guiding drum (1, 2). Treatment unit according to claim 1, characterized in that, the exterior sleeves (15) are connected through bends (16) to the connecting point of a link portion (8) and an outer pulling arm (9). Treatment unit according to claim 1 or 2, characterized in that the longitudinal wall facing away from the exterior sleeve (15) abuts the opposite exterior sleeve in an interior curve. Treatment unit according to any one of the preceding claims, characterized in that at the bottom side of the link portions grooves (19) are located, extending in the dirction of travel of the conveyor belt, the grooves (19) having a depth of more than half the thickness of the link portions (8), and a length extending up to or near the edge of the link portions which faces away fom the pulling arms (9).

Inventors: KAAK STEPHANUS WILLIBRORDUS, KAAK, STEPHANUS WILLIBRORDUS
Applicants: KAAK STEPHANUS W, KAAK, STEPHANUS WILLIBRORDUS
Application year: 1990
Main classification: B65G21
IPC codes: B65G17, B65G23, B65G15, B65G21