Abstract:
An apparatus having approximately parallel conveyors ( 2, 2 ′) for transporting and rotating an article (G) has multiple longitudinally arranged omnidirectional rollers ( 24 ), each omnidirectional roller ( 24 ) having multiple individual rollers ( 240 ) arranged about its periphery. The conveyors ( 2, 2 ′) extend in a transporting direction (T), bear against the bottom of the article (G), and rotate the article about an axis perpendicular to the article bearing plane. At least one conveyor can be driven at a speed different from the other conveyor to transport and rotate the article on the conveyor. The bearing portion of article (G) is subject to direction-dependent coefficients of friction with the transporting direction (T) having a static or sliding coefficient of friction that is higher than the rolling coefficient of friction in the direction perpendicular (S) to the transporting direction (T).

Description:
TECHNICAL FIELD 
   The invention relates to an apparatus for rotating an article. The apparatus is suitable, in particular, for transporting and rotating containers, for example boxes. 
   PRIOR ART 
   DE-A-39,15,246 discloses an apparatus which is intended for conveying articles and in which the articles are rotated in a controlled manner about an axis perpendicular to the conveying path as they are conveyed. Rotatable carriers, on which the articles which are to be rotated are arranged, are provided for this purpose. 
   DE-A-199,48,704 uses a turntable in order to rotate stacks of paper as they are transported. 
   EP-A-0,472,984 discloses a conveying and rotating apparatus with two conveying belts arranged one above the other. A round article which is to be rotated is transported on the bottom conveying belt which is provided with carry-along elements. Provided on the top conveying belt are downwardly projecting guide tracks which retain the article in position. Also provided are two lateral belts, which act on two opposite locations of the round article. The articles are rotated by virtue of the two lateral belts being driven at different speeds. 
   These apparatuses have the disadvantage that they have to be adapted to the shape and size of the articles which are to be transported. 
   Furthermore, DE-A-30,16,940 and EP-0,399,264 disclose apparatuses with lateral conveying belts which clamp in the articles which are to be rotated and rotate the latter by virtue of different conveying speeds. 
   These apparatuses mentioned above all have the disadvantage that they likewise have to be adapted to the respective size and shape of the articles. In addition, it is necessary for the static and sliding friction and the contact pressure to be optimized in each case in order that the articles can be rotated in a sufficiently precise position. 
   Transporting tables which can rotate articles are also known. The transporting tables are predominantly used in order to rotate the article in the desired direction at crossover points and branching locations. This is disclosed, for example, in DE-A-1,198,735 and U.S. Pat. No. 3,552,541. Further tables with omnidirectional rollers are described in U.S. Pat. No. 5,082,109, FR-A-2,798,122 and DE-A-2,202,256. 
   Such omnidirectional rollers have been known for some time now, for example in U.S. Pat. No. 3,363,735, U.S. Pat. No. 3,621,961, JP-2000335726 and DE-A-502,510. 
   DESCRIPTION OF THE INVENTION 
   It is an object of the invention to provide an apparatus which allows as precisely positioned rotation as possible and can be used for articles of different shapes and sizes. 
   This object is achieved by an apparatus having the features of patent claim  1 . 
   The apparatus according to the invention for rotating an article has means for bearing a base surface of the article which is to be transported, these means being arranged in a bearing plane. The article is rotated about an axis running perpendicularly to this bearing plane. At least two conveyers which extend in the transporting direction and run at least more or less parallel to one another are provided. At least a first of these conveyors can be driven, with the result that at least that part of the article which rests on the associated means is transported in the transporting direction by it. This first conveyor has a transporting speed which is different from that of the other conveyors. The means for bearing the article form a constituent part of the conveyors. These means have direction-dependent coefficients of friction in respect of the bearing plane, these coefficients of friction being greater, in particular, in the transporting direction than in the direction which is perpendicular thereto, and runs in the transporting plane. Static or sliding friction takes effect in the transporting direction; rolling friction is active perpendicularly thereto. 
   Since the articles merely have to be positioned on the conveyors, and there is no need for any further rotary means adapted specifically to the shape and size of the articles, the apparatus can be used for different articles without any changes in design. Since the articles do not have to be clamped in-between mounts, it is possible for difficult articles to be reliably transported and rotated. In addition, the force which is necessary for rotation is minimized. 
   It is further advantageous that the apparatus requires only a relatively small number of elements and is thus straightforward and cost-effective to produce. 
   Using the same means, the articles can be both transported efficiently along a path and also rotated simultaneously, with sufficient positional accuracy, about an axis perpendicular to the transporting plane. This allows low-friction rotation. In addition, the time taken to transport the article is not delayed by its rotation. 
   The efficiency of the transporting and/or of the rotation operation may additionally be increased by at least two of the conveyors being driven, with the result that, in addition to the difference in speed which is necessary for the rotary movement, there is a common speed component which transports the article forward as it is rotated. The conveyors thus serve as longitudinal conveyors and as rotary conveyors. 
   It is also possible, however, for just one of the conveyors to be driven and thus merely for rotation to be carried out. It is further possible for one of the conveyors to move the article in the forward direction and for another conveyor to move it in the rearward direction, with the result that the article is rotated on the spot. In these two cases, the article is transported forward by other, known means, for example, slides, lateral conveying belts or conveying means which are adjacent to the conveyors according to the invention. 
   Each conveyor preferably has a plurality of such means, the means being arranged individually or in groups one behind the other in the transporting direction and having rollers. Each of these rollers preferably has an axis of rotation which, at least in the state in which the roller is in contact with the base surface of the article, runs at least more or less parallel to the transporting direction. The roller is preferably freely rotatable about this axis of rotation. 
   In a preferred embodiment, the rollers are retained in cages which can be rotated about an axis perpendicular to the transporting direction. These cage/roller structures are preferably omnidirectional rollers. 
   In another preferred embodiment, the contacting means are individual longitudinal rollers which are arranged one behind the other in the transporting direction on a strand-like pulling means. 
   The positional accuracy can be increased by aligning means which are arranged downstream of the longitudinal and rotary conveyors in the transporting direction. Such aligning means are, for example, lateral guides and/or separately driven and moveable stopper elements. 
   Further advantageous embodiments can be gathered from the dependent patent claims. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The subject matter of the invention is explained hereinbelow with reference to preferred exemplary embodiments which are illustrated in the attached drawings, in which: 
       FIG. 1  shows a perspective view of a first embodiment of the apparatus according to the invention; 
       FIG. 2  shows a detail of the apparatus according to  FIG. 1  with boxes arranged thereon; 
       FIG. 3  shows a perspective view of part of the apparatus according to  FIG. 1  with omnidirectional rollers and a drive illustrated; 
       FIG. 4   a  shows a perspective view of an omnidirectional roller; 
       FIG. 4   b  shows a view of the omnidirectional roller according to  FIG. 4   a  from above; 
       FIG. 4   c  shows a side view of the omnidirectional roller according to  FIG. 4   a;    
       FIG. 5  shows a perspective view of a second embodiment of the apparatus according to the invention; and 
       FIG. 6  shows a perspective view of the essential parts of a third embodiment of the apparatus according to the invention. 
   

   METHODS OF IMPLEMENTING THE INVENTION 
     FIG. 1  illustrates a first exemplary embodiment of the apparatus according to the invention. Two longitudinal and rotary conveyors  2 ,  2 ′ are arranged on two spaced-apart side panels  10  of a framework  1 . These longitudinal and rotary conveyers  2 ,  2 ′ extend along a transporting direction T which is illustrated by an arrow. The corresponding rotary and transporting planes for the articles G which are to be transported and rotated, and are illustrated in  FIG. 2 , thus preferably run horizontally. 
   The longitudinal and rotary conveyors  2 ,  2 ′ are followed by a horizontal conveyor  3 . The latter may be arranged on the same or a different framework  1 . An aligning means, in this case a stopping means  4 , is preferably provided in the region of the horizontal conveyor  3 . 
   In the example illustrated here, each of the longitudinal and rotary conveyors  2 ,  2 ′ is formed by a plurality of omnidirectional rollers  24  which are arranged individually one behind the other in the transporting direction T. It is also possible, however, for them to be arranged in groups one behind the other. Such omnidirectional rollers  24  are known from the prior art. Just one possible embodiment thereof will be described here. As is illustrated in  FIGS. 4   a  to  4   c , they have a cage  241  in which convex elongated rollers  240  are retained. The rollers  240  are distributed uniformly over the circumference of the cage  241  and can be rotated freely about axes of rotation D. For the apparatus according to the invention, as is illustrated here, use is preferably made of double-row omnidirectional rollers, in the case of which the rollers  240  of the two rows are offset by an angle in relation to one another. This ensures that the article rests on a roller  240  in each rotary position of the cage  241 . The omnidirectional rollers  24  used here have direction-dependent coefficients of friction in respect of the bearing plane, these coefficients of friction preferably being greater in the transporting direction T than those in a direction S which is perpendicular thereto. It is also possible, for example, for two straightforward omnidirectional rollers to be arranged such that they are turned at an angle one beside the other on a common axis of rotation. 
   As can be seen in  FIG. 3 , the omnidirectional rollers  24  arranged one behind the other, and/or their cages  241 , are arranged on a respective shaft, which defines the axis of rotation K for the cages. These axes of rotation K run parallel to the bearing plane, but perpendicular to the transporting direction T. The shafts are driven together. Each conveyor  2 ,  2 ′ has a dedicated drive. The shafts of each conveyor  2 ,  2 ′ are connected to one another via a common drive means, in this case a circulating drive chain  23 . The chain  23  engages in a plurality of gear mechanisms  22 , which are each connected to one of the axes K. The chain  23  and the gear mechanisms  22  are preferably arranged in the side panels  10 . Each chain  23  is connected to a dedicated drive motor  20 , which is illustrated in  FIG. 1 . Each conveyor  2 ,  2 ′ thus has a dedicated drive. 
   It can be seen in  FIG. 2  how, by means of the apparatus according to the invention, an article G, in this case a box, is rotated and, at the same time, transported. This takes place by virtue of the two conveyors  2 ,  2 ′ being driven differently, with the result that they have different transporting speeds. This means that the cages  241  belonging to a common conveyor  2 ,  2 ′ are rotated at the same speed about the axis of rotation K, the cages  241  of different conveyors  2 ,  2 ′ having different speeds of rotation. Since the box rests on the rollers  241 , and the axes of rotation D of the latter, in this state of contact, run parallel to the transporting direction T, the box is rotated about an axis A perpendicular to the bearing plane and, at the same time, transported forward. The angle of rotation achieved depends on the relative speed of the conveyors  2 ,  2 ′. In this case, the box has been rotated through 90°. Corresponding control of the drive of the conveyors  2 ,  2 ′, however, make it possible to achieve any desired angles of rotation. 
   The article G can be aligned even more precisely following rotation. The stopping means  4  is provided for this purpose in  FIG. 1 . It has two parallel, preferably synchronously driven circulating conveying chains  40  and at least one stopping element  41  which is fixed to the conveying chain  40 . Two or more stopping elements  41  are preferably provided. The rotated article leaves the conveyors  2 ,  2 ′ following rotation and passes downstream onto the horizontal conveyor  3 , which in this case is formed by two parallel, preferably synchronously driven conveying belts. The stopping elements  41 , which are arranged in relation to one another at the desired angle of rotation for the article, serve as a stop for the incoming box and align the latter, if appropriate, to the full extent. 
   A different aligning method is illustrated in  FIG. 5 . Here, a lateral guide means  5  is provided as the aligning means. The guide means has in each case one lateral conveying belt  51  which is arranged on one side of the transporting path in each case and runs around a drive roller  50  and a deflecting roller. These two conveying belts  51  accommodate the box and align it further. Depending on the type of article, there is no need for the horizontal conveyors  3  in this case. It is also possible, however, to use the lateral guide means  5  together with the above described stopping means  4 . 
     FIG. 6  illustrates a further exemplary embodiment of the apparatus according to the invention. In this case, use is made, instead of omnidirectional rollers, of convex longitudinal rollers  25  which are fixed in position on a circulating strand-like pulling means  26 , for example a wire cable, but are freely rotatable about their longitudinal axis D. Only the top strand of the pulling means  26  is illustrated in  FIG. 6 . The pulling means  26  circulates in a known manner about a deflecting roller and is driven by a drive roller. As is illustrated here, each longitudinal and rotary conveyor  2 ,  2 ′ has exactly one pulling means  26 . It is also possible, however, for two or more pulling means  26  to be arranged one beside the other and to be driven together. As in the embodiments described above, the pulling means  26  of the two conveyors  2 ,  2 ′ are also provided with different transporting speeds for conveying the boxes G. Forward transportation takes place by the pulling means circulating in the transporting direction T. Rotation takes place by virtue of the relative speed between the two conveyors  2 ,  2 ′ and the freely rotatable longitudinal rollers  25 . Here too, the longitudinal rollers  25  thus have direction-dependent coefficients of friction in respect of the bearing plane, these coefficients of friction preferably being greater in the transporting direction T than those in the direction S which is perpendicular thereto. 
   The apparatus according to the invention thus allows straightforward rotation and transportation of articles, there being barely any need for the apparatus to be adapted to the shape and size of the articles. 
   LIST OF DESIGNATIONS 
   
       
       G Article 
       T Transporting direction 
       S Direction running in the transporting plane and perpendicularly to the transporting direction 
       A Axis of rotation of the article 
       D Axis of rotation of the roller 
       K Axis of rotation of the cage 
         1  Framework 
         10  Side panels 
         2  First longitudinal and rotary conveyor 
         2 ′ Second longitudinal and rotary conveyor 
         20  Drive motor 
         22  Gear mechanism 
         23  Drive chain 
         24  Omnidirectional roller 
         240  Roller 
         241  Cage 
         25  Longitudinal roller 
         26  Strand-like pulling means 
         3  Horizontal conveyor 
         4  Stopping means 
         40  Conveying chain 
         41  Stopping element 
         5  Lateral guide means 
         50  Drive roller 
         51  Lateral conveying belt
 
The entire disclosure of Switzerland Patent Application No. 01251/03 filed Jul. 17, 2003 is incorporated by reference.