Abstract:
The invention relates to a conveyor system ( 1 ) designed as a belt conveyor system and comprising a conveyor belt ( 5 ) that loops around the conveyor roller ( 2 ) at least partially, wherein the conveyor roller ( 2 ) is mounted on at least one side via a bearing pot ( 6 ) having, at least over a loop region of the conveyor belt ( 5 ) a radius substantially equal to or somewhat smaller than the radius of the conveyor roller ( 2 ) in the axial end region of the conveyor roller ( 2 ), wherein the conveyor belt ( 5 ) is wider than the length of the conveyor roller ( 2 ) in the axial direction and wherein the conveyor belt ( 5 ) is disposed on the conveyor roller ( 2 ) such that the gap ( 7 ) between the conveyor roller ( 2 ) and the bearing pot ( 6 ) is covered by the conveyor belt ( 5 ).

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention relates to a conveyor system. 
     2. Description of the Related Art 
     Drift conveyors, such as conveyor belts, usually have a plurality of conveyor rollers rotatably supported in a frame of the drift conveyor. Some of these conveyor rollers have an antifriction bearing in the interior of the roller for the rotatable support of the conveyor roller. In other designs, an antifriction bearing is arranged on the frame of the drift conveyor, and the conveyor rollers only have an axle neck, which is supported in the antifriction bearing. 
     Such rollers are mass-produced articles so that even slight improvements in the manufacture of the conveyor rollers would lead to considerable economies of scale. 
     In directly or indirectly (such as via a conveyor belt) driven conveyor rollers, moreover, the gap between the stationary frame and the rotating conveyor roller is a danger spot. 
     A possibility for supporting a conveyor roller which also contributes to removing the danger spot is disclosed, for example, in German Patent Specification DE 33 08 262 C1. In this document, a conveyor roller is disclosed wherein the drum shell axially projects beyond an axle. The conveyor roller is supported in a bearing profile via a block-like bearing element, which protrudes into the projecting drum shell. By these means, the gap between the stationary and rotating parts is covered by the projecting drum shell. In the conveyor roller shown, the axle is welded into a circular metal sheet part having a central hole, and the metal sheet part, in turn, is welded into the drum shell. 
     The manufacture of such a conveyor roller involves a relatively large amount of work and cost. 
     It is therefore the object of the invention to provide a conveyor system having a conveyor belt, wherein the danger spot between the conveyor roller and neighboring stationary parts has been removed, and also to create a design for the support of a conveyor roller in such a conveyor system, which is cost-effective to manufacture. 
     SUMMARY OF THE INVENTION 
     One aspect of the invention relates to a conveyor system configured as a belt conveyor system, and comprising a conveyor belt which is at least partially wrapped around the conveyor roller, wherein the conveyor roller at least on one side is supported in a bearing cup having a radius which, at least in an angle of wrap of the conveyor belt, is essentially equal to or slightly smaller than the radius of the conveyor roller in the axial end region of the conveyor roller, wherein the conveyor belt is wider than the length of the conveyor roller in the axial direction, and wherein the conveyor belt is arranged on the conveyor roller in such a manner that the gap between the conveyor roller and the bearing cup is covered by the conveyor belt. 
     The angle of wrap depends on the degree of redirecting of the conveyor belt on the conveyor roller. If the conveyor roller is used as a return roller at the end of a conveyor belt, the angle of wrap can be 180° or more. In the case of a conveyor roller which is used between the ends of a conveyor belt, the angle of wrap can be just a point on the circumference in cross-section, or can be in the form of a line extending in the longitudinal direction of the conveyor roller. The bearing cup is used to mount the conveyor roller in a frame of the conveyor system. Herein, the gap which would arise between the frame and the conveyor roller in conventional bearings is displaced toward the roller center of the conveyor roller. Surprisingly, it has become apparent that depending on the configuration of the conveyor cup, or the conveyor roller, the relative movement between the conveyor belt, which is carried across the surface of the conveyor cup in a sliding manner, does not lead to undesirable wearing of the conveyor belt. This can be explained by the fact that, in particular with a larger diameter of the conveyor roller in the roller end region of the conveyor roller with respect to the diameter of the bearing cup, the belt tension is negligible in the region of the bearing cup. This effect can also be seen if the radius of the bearing cup in the region of wrap is essentially equal to the radius of the conveyor roller in the roller end region, if the conveyor roller has a crowned configuration, that is it has a greater diameter in the center region of the roller than in the roller end region. Independently of the configuration of the radii or diameters of the bearing cup and the conveyor roller, wear phenomena can be reduced or even eliminated also by a particularly smooth surface finish of the bearing cup and/or a suitable choice of materials for the bearing cup and the conveyor belt. Preferably, the bearing cup is made of steel. Herein, the conveyor roller is supported by one bearing cup on each of both sides. 
     Furthermore, an embodiment of the conveyor system is preferred, in which the bearing cup, in the angle of wrap, has a radius smaller by between 0.3 mm and 2.5 mm than the radius of the conveyor roller in the axial end region of the conveyer roller. 
     A further advantageous embodiment relates to a conveyor system, wherein the bearing cup, in the angle of wrap, has a roughness depth of, for example, Ra 3.2 or Ra 6.3, wherein the roughness height of Ra 6.3 is particularly preferred. 
     Preferably, such a conveyor system has a configuration, wherein the conveyor roller has a crowned configuration, wherein the roller center diameter in the central region of the conveyor roller is between 1 mm and 2 mm, more preferably about 1.5 mm, larger than the roller end diameter of the conveyor roller in a roller end region. The term roller end region refers to the region of the axial ends of the conveyor roller. The term crowned as used in the present case, comprises both a rounded convex configuration of the surface and a preferred configuration, wherein the conveyor roller has two essentially conical regions, which flair beginning from the roller end regions to the center of the conveyor roller and are joined in the central region of the roller by an essentially circular-cylindrical region, wherein the axial length of each of the three regions preferably essentially corresponds to a third of the roller length. 
     Furthermore, such a conveyor system is preferred, wherein at least one bearing, on which the conveyor roller is rotatably supported, is received in the bearing cup. Such a bearing can be a sliding bearing. Preferably, the bearing is formed as an antifriction bearing, and more preferably as a self-aligning ball bearing. Herein, the conveyor roller is preferably supported on both sides by a self-aligning ball bearing in a bearing cup on each side. 
     A further advantageous embodiment relates to such a conveyor system, wherein the conveyor roller is rotatably supported by an axle pin that is arranged on the conveyor roller in a manner resistant against rotation and axial displacement and has a bearing region projecting beyond the roller end region of the conveyor roller in the axial direction and has a bearing diameter corresponding to an inner bearing ring of the antifriction bearing in this region. 
     Furthermore, a configuration of a conveyor system is preferred, wherein the axle pin is fixed in the conveyor roller by means of a shaft-hub assembly, further including a elastically deformable expansion element and a hub, wherein the axle pin has an axle region with an axle cross-section essentially corresponding to a hub cross-section of a corresponding hub region of the hub in such a manner that the axle pin arranged in the hub is fixed in the radial direction with respect to the hub, wherein the axle pin has an axle rotation locking region and the hub has a hub rotation locking region, wherein the axle rotation locking region and the hub rotation locking region are configured in such a manner that the axle pin arranged in the hub is fixed against rotation in the circumferential direction with respect to the hub, and wherein the expansion element is arranged on the axle pin, has an outer peripheral region and is configured in such a manner that the outer peripheral region has an outer diameter in the relaxed state of the expansion element that is larger than an inner diameter of a corresponding inner peripheral region of the hub, wherein the expansion element, while the axle pin is arranged within the hub, is elastically deformed in such a way that the outer peripheral region of the expansion element is displaced from the relaxed position of the expansion element in the axial direction of the axle pin and wherein the axial displacement of the outer peripheral region of the expansion element is coupled to a reduction of the outer diameter of the outer peripheral region of the expansion element in such a manner that the reduced outer diameter of the expansion element corresponds to the inner diameter of the corresponding inner peripheral region of the hub against which it is in pre-stressed contact. 
     The axle region and the hub region preferably have an essentially cylindrical configuration, which means that the corresponding surfaces can essentially be described as surfaces which are each created by the parallel displacement of a line extending parallel to the axis of the axle pin along any closed curve in space. By these means it is ensured that the axle region and the hub region can be easily pushed one into the other during assembly. The two regions are particularly easy to manufacture if they have an essentially circular-cylindrical cross-section. Cross-sectional shapes deviating from the circular-cylindrical shape have the advantage, however, that they simultaneously realize the function of the axle rotation locking region or the hub rotation locking region without having to press the hub and the axle pin one into the other or without having to provide additional components. The axial displacement of the outer peripheral region, which is coupled to a reduction of the outer diameter, describes a combined movement of the outer diameter having an axial component and a radial component. The displacement in the axial direction runs against the direction of insertion of the axle pin into the hub. By means of such movement extending at an oblique angle to the axis of the axle pin, fixing of the axle pin is effected in the hub. The terms shaft, hub and axle pin in the form used here refer to components transmitting torques as well as components that do not transmit a torque. 
     Furthermore, such a conveyor system preferably has a configuration, wherein the expansion element and the corresponding inner peripheral region of the hub are formed in such a manner that due to the coefficient of friction between the expansion element and the inner peripheral region and by means of a displacement angle between the displaced regions of the expansion element, having the outer peripheral region of the expansion element arranged at their radial ends, and the inner peripheral region of the expansion element, a self-locking effect of the expansion element is created in the hub. The displaced regions of the expansion element can be formed, for example, preferably as finger-like extensions, wherein their ends form the outer peripheral region and wherein the sides of the finger-like extensions, which face the outer peripheral region, are mounted on an expansion element base. In the context of the elastic deformation, such a finger-like extension is essentially deformed in the region of the point of attachment on the expansion element base, so that the remaining portion of the finger-like extension is pivoted as a displaced region of the expansion element about the displacement angle in an essentially undeformed state. Herein, the region of the finger-like extension which is referred to as the outer peripheral region, carries out the described combined movement in the axial and radial directions. The term self-locking means that, as a force is applied to the axial pin in the axial direction against an introduction direction of the axle pin, a normal force resulting from this force is created between the outer peripheral region of the expansion element and the inner peripheral region of the hub, which, taking the coefficient of friction between the outer peripheral region of the expansion element and the inner peripheral region of the hub into consideration, results in a frictional force which is greater than the force applied to the axle pin in the axial direction against the introduction direction of the axle pin (not taking the frictional force into account which is created by the spring force of the expansion element). By means of this configuration, the axle pin together with the expansion element can be pushed into the hub and is fixed in the inserted position in the hub in a direction against the introduction direction. Alternatively or additionally, fixing can be effected by selecting the material pairing between the material of the expansion element and the material of the hub in such a manner that the outer peripheral region of the expansion element can penetrate the surface of the inner peripheral region of the hub during expansion, so that the self-locking effect is replaced or reinforced by an interlocking engagement. Herein, the outer peripheral region of the expansion element is preferably formed with a sharp edge in such a manner that penetration into the surface of the inner peripheral region of the hub is facilitated. 
     Furthermore, such an embodiment of the conveyor system is preferred, wherein the expansion element is configured as a disk or preferably as a closed ring, wherein the expansion element has slots spaced in the circumferential direction, which extend from the outer peripheral region essentially radially in such a manner toward the inside, that the outer peripheral region is formed by the ends of a number of finger-like extensions mutually separated in the circumferential direction by slots. Herein, the expansion element preferably configured as a closed ring can have, for example, the basic shape of a washer, having slots directed from the outside toward the inside. Such a slotted washer has a substantially planar configuration in the relaxed state. It is also conceivable that the expansion element already has a plate-like basic shape in the relaxed state, wherein the plate edge has a substantially conical form. Such a configuration facilitates the insertion of the axle pin together with the expansion element into the hub. Preferably, in both cases, the slots essentially extend radially from the outside toward the inside or have an essentially V-shaped configuration. Other slot forms, such as recesses spiraling towards the inside, are also conceivable. 
     Another advantageous embodiment relates to such a conveyor system, wherein the expansion element on the axle pin is preferably arranged on an axial end of the axle pin, and/or is attached on the axle pin by riveting, welding, screwing or any other type of connection. A radial play has the advantageous effect that the expansion element can expand independently of a precise rotation-symmetrical arrangement with respect to the axis of the axle pin, in a uniform manner during insertion into the hub. In this way, double fitting is avoided. 
     Furthermore, an embodiment of the conveyer system is preferred, wherein the axle pin region of the axle pin, which is received in the hub, has an essentially circular-cylindrically form and wherein the diameter of the axle pin region and a diameter of a corresponding hub receiving region of the hub form a sliding fit, a slight press fit or a press fit, which comprise, for example, the H7-g8 or H7-p8 fits. The circular cylindrical shape is particularly easy and therefore cost-effective to make. A sliding fit is particularly easily assembled. Due to the expansion element, an interference fit is not necessary to fix the axle pin within the hub. A slight press fit can be advantageous, however, if no or only small torques are to be transmitted since in this case an interlocking engagement, which is costly to make, can be avoided by means of a slight press fit. 
     A further advantageous embodiment relates to a conveyor system, wherein the diameter of the hub is essentially the same across the entire insertion length of the axle pin. In this embodiment, the axle region or the hub region is at least partially identical with the axle rotation locking region and the hub rotation locking region. Herein, a rotation lock is preferably achieved by means of a press fit. 
     Preferably such a conveyor system has a configuration, wherein a rotation locking region between the axle pin and the hub is formed as an interlocking engagement region. Preferably, such an interlocking engagement region is achieved by a feather key arranged as a separate element in a keyway of the axle pin and in a keyway of the hub. Other forms of interlocking engagement, such as a non-rotation symmetrical configuration of the corresponding cross-sections of the axle pin and the hub, for example, in the form of a spline profile, are also conceivable. 
     Furthermore, such a conveyor system is preferred, wherein the expansion element is of steel. Preferably, the expansion element is of hardened spring steel. Due to the hardness of spring steel, the expansion element can easily expand into the softer materials of the hub. Herein, the hub can be of non-hardened steel, aluminum or plastic material, for example, or can include such materials. With softer materials, such as plastic material or aluminum, it can suffice if the expansion element is of non-hardened steel or another metal, since these materials of the expansion element can also have sufficient elasticity and hardness with respect to their respective hub material. Other materials are also conceivable, which have sufficient elasticity and hardness. 
     A further advantageous embodiment relates to such a conveyor system, wherein the hub is made of an aluminum alloy. Aluminum or an aluminum alloy has the advantage, that this material is easily manufactured, for example, by means of continuous casting, or can be easily extruded. Herein, it is possible to make the hub together with a drum shell and any struts required between them in one processing step. 
     Individual, particularly preferred embodiments of the invention will be described in the following in an exemplary manner. The individually described embodiments in part have features that are not absolutely necessary for implementation of the present invention, but that are generally deemed advantageous. Thus, embodiments which do not have all the features of the embodiments described in the following will also be considered as falling under the teachings of the invention. It is also conceivable to selectively combine features described with reference to different embodiments. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  shows an isometric view of a conveyor system in a partial cutaway view; 
         FIG. 2  shows the conveyor system of  FIG. 1  in a front view in a partial-sectional view; 
         FIG. 3  is an enlarged view of the conveyor system of  FIG. 2 ; 
         FIG. 4  shows an assembly of the conveyor system having two bearing cups and a bearing roller with cutaway regions and a cross-sectional view of the conveyor roller; 
         FIG. 5  is an isometric view of a axle pin with an expansion element arranged on it; 
         FIG. 6   a  is an isometric sectional view of the expansion element; and  FIG. 6   b  shows detail A of  FIG. 6   a.    
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       FIG. 1  is an isometric view of a conveyor system  1  in a partial-sectional view. 
     Conveyor system  1  is formed as a belt conveyor.  FIG. 1  shows the return region of a conveyor belt  5  redirected by 180° via a conveyor roller  2 . Conveyor belt  5  is thus in contact with conveyor roller  2  with an angle of wrap of about 180°. 
     Conveyor roller  2  is rotatably supported between two bearing cups  6 . Bearing cups  6  are fixed on a frame in a rotation-resistant manner. In operation, conveyor roller  2  thus rotates relative to bearing cups  6  or relative to the frame of conveyor system  1 . 
     To support conveyor roller  2 , a bearing  61  is provided in each of stationary bearing cups  6 , configured as an anti-friction bearing, in particular a self-adjusting ball bearing in the present embodiment. Herein, conveyor roller  2  is supported by one axle pin  81  in each of bearings  61 . 
       FIG. 2  shows conveyor system  1  of  FIG. 1  in a front view in partial cross-section, and  FIG. 3  shows an enlarged view of conveyor system  1  of  FIG. 2 . Each of the figures shows the same embodiment of preferred conveyor system  1 . This is why the same reference numerals will be used for each of the same parts. 
       FIG. 3  shows axle pin  81  in a partial cross-section of conveyor system  1 . It can be seen that axle pin  81  has an axle pin region  812  received in a hub receiving region  821  of a hub  82 . In the preferred embodiment shown, axle pin region  812  is formed as an essentially circular-cylindrical body and is inserted in the hub receiving region  821  of hub  82  also formed as a circular-cylindrical hole. Herein, the tolerances of hub receiving region  821  and axle pin region  812  are dimensioned as a slight press fit. To ensure secure fitting of axle pin  81  within hub  82 , an expansion element  83  is provided in an axial end  811  of axle pin  81 , which preferably ensures a release-secure connection between axle pin  81  and conveyor roller  2 . 
     The cross-section of the preferred conveyor roller  2  is shown in  FIG. 4 . 
       FIG. 4  shows an assembly of conveyor system  1  having two bearing cups  6  and a conveyor roller  2  with cutaway portions and a cross-sectional view of conveyor roller  2 . 
     It is shown in  FIG. 4  that hub  82 , a conveyor roller shell of conveyor roller  2  and connecting webs between hub  82  and the conveyor roller shell are integrally formed. The manufacture of such a conveyor roller  2  can be carried out, for example, in the continuous casting method. A preferred material for conveyor roller  2  is aluminum or an aluminum alloy. It is also conceivable to manufacture conveyor roller  2  in any other form, such as assembled of several parts. A conveyor roller  2  manufactured in the continuous casting method has essentially the same cross-section over the entire length of conveyor roller  2 . A crowned shape of conveyor roller  2 , which is a preferred shape of conveyor roller  2 , is preferably created in a processing step by later turning the shell surface of conveyor roller  2 . 
     The crowned shape of conveyor roller  2  has the advantageous effect that a conveyor belt redirected or supported by conveyor roller  2  is centered and does not run off center from the conveyor roller in the axial direction. In the preferred embodiment having two bearing cups  6  in which conveyor roller  2  is rotatably supported, the crowned shape of conveyor roller  2  has the further advantage that the edge regions of conveyor belt  5  remain essentially stress free. 
     As can be seen from  FIG. 3 , bearing cup  6  has a slightly smaller diameter than adjacent roller end region  4  of conveyor roller  2 . This configuration, in addition to the crowned shape of conveyor roller  2 , contributes to a reduction of the friction between conveyor belt  5  and bearing cup  6 . 
     In a particularly preferred embodiment, bearing cup  6 , at least in the angle of wrap of conveyor belt  5 , is provided with a smooth surface, so that any undesirable friction can be further reduced. A preferred roughness height, with which bearing cup  6  is provided at least in this region, is Ra 6.3. 
     As can also be seen from  FIG. 3 , axle pin  81 , on the side opposite expansion element  83 , is provided with a bearing region  813 , which preferably also has a circular-cylindrical configuration and a diameter for forming a desired fit with bearing inner ring  62  of bearing  61 . Herein, bearing region  813  is preferably formed as a fixed bearing on one side of conveyor roller  2  and as a loose bearing on the other side of conveyor roller  2 . 
       FIG. 5  is an isometric view of axle pin  81  with an expansion element  83  arranged thereon. 
     As can be clearly seen from this figure, an axle rotation locking region  814  is provided on axle pin  81  which, in the preferred embodiment shown, is formed by means of a keyway in axle pin  81 , in which a feather key is inserted. In the embodiment shown it can be further seen, that, between bearing region  813  and axle region  815 , a collar having a greater diameter is provided, which serves as a stop in both directions. 
     It is also conceivable, instead of a feather key, to provide a press fit between axle pin  81  and hub  82 . Other embodiments are also conceivable, which ensure a rotation lock between hub  82  and axle pin  81 . In particular, for non-driven conveyor rollers  2  or with conveyor rollers which only need to transmit a small torque, a slight press fit is sufficient, which can also be created between axle pin  81  and hub  82  which is preferably made of an aluminum alloy. 
     Expansion element  83  is arranged on an axial end  811  of axle pin  81 . In the preferred embodiment shown, expansion element  83  is riveted onto axle pin  81 . It is also conceivable to attach expansion element  83  on the axle pin in a different way, such as by means of screwing, welding, etc. 
       FIG. 6   a  is an isometric sectional view of a preferred expansion element  83 , which is also shown in  FIG. 5 . 
     As shown in  FIG. 6   a , the basic form of preferred expansion element  83  essentially corresponds to the shape of a plate, wherein the edges of the plate have a conical configuration. In the center of expansion element  83 , a hole is preferably disposed, through which a rivet or a screw can be passed for attachment. 
     In the preferred embodiment shown, expansion element  83  is formed as a closed ring about the hole, from which finger-like extensions  33  extend toward the outside in a radial direction. In other words, slots  832  extend from an outer peripheral region  831  of expansion element  83  toward the inside and subdivide the circumferential region into partial regions. Slots  832  can have a V-shaped configuration as shown in the preferred embodiment shown, and can extend essentially radially toward the inside. Other embodiments are also conceivable, wherein slots alternatively or additionally extend from the inside toward the outside, so that the ring essentially has a zig zag shape. It is also conceivable to configure the ring not as a closed ring but as a ring that is completely interrupted in one place and has two open ends. 
     In the preferred embodiment shown, slots  832  essentially extend from the outer peripheral region  831  to a fold formed between the plate edge and the planar plate surface, toward the inside. It is also conceivable that the slots further extend to the center of expansion element  83  or are made shorter. 
       FIG. 6   b  shows a detail A of  FIG. 6   a.    
     In this figure, the position of finger-like extension  833  is shown in broken lines, in which the finger would be in a planar configuration of expansion element  83  in the relaxed state (in a fictive planar configuration). From this relaxed position, finger-like extension  833  can be displaced into the stressed position by an angle α, as is shown as a hatched area in  FIG. 6   b . In the preferred embodiment of plate-like expansion element  83 , the relaxed position would be between the two positions shown. In both cases it can be seen that expansion element  83 , in its relaxed position, has a diameter D I , which corresponds to the diameter of the inner peripheral region of hub  82 . Such a diameter D I  can be in the range of 31.3 mm, for example. Furthermore, expansion element  83 , in its relaxed state, has a diameter that is greater than diameter D I . Such a diameter D A  can be, for example, in the range of 31.7 mm. 
     As axle pin  81  is inserted into hub  82 , finger-like extensions  833  are displaced and come into pre-stressed contact with the inner peripheral region of hub  82 . The friction between outer peripheral region  831  of expansion element  83  and the inner peripheral region of hub  82  creates a frictional force that, if axle pin  81  should be pulled out of hub  82 , finger-like extensions  833  are pushed toward their relaxed position. Concurrently with this force, the pressure between outer peripheral region  831  and the inner peripheral region of hub  82  is increased, since the reverse displacement into the relaxed positions would be concurrent with an increase in the diameter. By means of this configuration it is ensured that the frictional force between outer peripheral region  831  and the inner peripheral region of hub  82  is preferably always greater than the force exerted on axle pin  81 . 
     This effect can be reinforced by giving outer peripheral region  831  a sharp edge, so that, in particular if the material of expansion element  83  is harder than the material of hub  82 , outer peripheral region  831  can penetrate the inner peripheral region of hub  82 . This effects, in addition to the frictional engagement, an interlocking engagement which creates a particularly strong anchoring effect of axle pin  81  within hub  82 .