Abstract:
A device ( 10 ) for feeding bulk material items ( 12 ) from a large mass into a randomly re-alignable, individually portioned disentangled position within the reach of a robot ( 18 ). A vision system comprising a camera ( 26 ) or a sensor records the number, position and alignment of the separated bulk material items ( 12 ). A processor ( 56 ) processes the sensor signals and generates control commands in actuators. The entire surface area of a one-piece oscillating conveyer surface ( 16 ) is supported by an oscillating conveyor arm ( 44 ). The surface lies on top of the arm and is horizontally displaceable in the x- or the x- and y-direction, extending together with the oscillating conveyor arm ( 44 ) and projecting in a freely supported manner from a storage zone ( 40 ) across a distribution zone ( 42 ) up to one front end of a selection zone ( 28 ) for the bulk material items ( 12 ). An oscillating motion (S) is generated in the z-direction with a continuously increasing amplitude (A) in the x-direction. The oscillating motion (S) alternates or is at least partially synchronous and co-ordinated with a forward feed or reverse transport of the bulk material items ( 12 ) in the x- or x- and y-direction.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     The invention relates to a device and a method for feeding bulk material items from a mass multiply arranged one above the other in a store into a randomly re-alignable, individually distributed and disentangled position within the reach of a robot, the device comprising a substantially horizontally arranged oscillating conveyor surface with means for the forward feed or reverse transport of the bulk material items in the x-direction or in the x- and y-direction of the space coordinates, means for exciting an at least partial oscillation of the oscillating conveyor surface in the z-direction of the space coordinates, a vision system with a camera or a sensor for individual detection of the number, position and alignment of the individual bulk material items, and a processor for processing the sensor signals and generating control commands to actuators.  
         [0002]     In the industrial production and fitting of consumer goods, more or less complicated mass-produced parts are frequently provided in bulk material form for further processing. For the following processing and/or fitting operations, the bulk material items are required to be disentangled, separated and in a position which is aligned in a defined manner. Vibrating spiral conveyors, in which mechanical baffles are provided along a conveyor spiral, are often used for this purpose. These align the bulk material items along their conveying direction or eliminate them so that only correctly aligned bulk material items arrive at the discharge site. An additional mechanical apparatus can arrange the separation and fine positioning of the bulk material items which can be controlled and removed by a handling system or a robot owing to these preparatory operations.  
         [0003]     The arrangement and design of baffles has to be specifically optimised for each type of bulk material item. The flexibility of the spiral conveyor has been further improved in the last 10 to 15 years by the use of active baffles (sensor/actuator) and replaceable baffles/positioning stations but these cannot yet meet the current demands from industry for flexible self-correcting feeds which can be programmed for different bulk material items.  
         [0004]     A plurality of known flexible feed systems consist of one unit which mechanically processes the bulk material items such that they are recognised by a vision system known as an image processing system (machine vision) and can be removed by a robot. Bulk material items which are not recognised migrate back into the provided bulk material and reappear at a later instant.  
         [0005]     In a known device for flexibly feeding bulk material items  12  according to  FIG. 1 , these are partially processed in a store  14 . The bulk material items  12  leave the store  14  on a conveyor surface  16  and migrate in the direction of a robot  18  with a pivoting arm  20 , which has a gripper tool  24  for bulk material items  12 , which can be rotated about this shaft  22  and is fastened at the end face to a height-adjustable shaft  22 .  
         [0006]     A camera  26  determines, in a selection zone  28  which is shown by dotted lines, the exact position of the bulk material items  12  in the desired preferred position. With the aid of transmitted data, a robot controller  30  calculates the coordinates and correspondingly triggers the actuators of the robot  18 , which grasps the bulk material items  12  that are arranged in the mentioned desired preferred position, in the speed of seconds. The removed bulk material items  12  are placed on a conveyor belt  34  and supplied for further processing and this is indicated by an arrow  32 .  
         [0007]     The bulk material items  12  which are not grasped by the robot  18 , on the other hand, are recycled in the store  14  and guided again in random arrangement into the selection zone  28  by way of the conveyor surface  16  with further bulk material items  12  stored in the store.  
         [0008]     All the bulk material items  12  contained in the store  14  have to be replaced at periodic intervals, so defective bulk material items  12  do not remain in constant rotation.  
         [0009]     U.S. Pat. No. 5,687,831 describes a device for feeding bulk material items, which contains a substantially horizontal conveyor surface. The bulk material items are transported to a selection zone, where the arranged and aligned bulk material items are located by means of a video camera, grasped by a robot and transferred to a fitting system. The bulk material items which are not removed are guided back to the beginning of the conveyor surface by means of a recirculation system for a renewed passage. During the return, the position and alignment of the bulk material items is changed such that they are aligned as favourably as possible during the next passage and can possibly be selected and removed in the selection zone. The device according to U.S. Pat. No. 5,687,831 can probably process a wide variety of bulk material item shapes but it is constructionally relatively complex and requires a substantial overall volume for the arrangement of the conveying surface, the selection zone and the recirculation system.  
         [0010]     In a device for flexibly feeding bulk material items according to U.S. Pat. No. 6,056,108, a flexible membrane is arranged for the transport of flexible bulk material items, on which membrane a selection zone is defined. In this region, the position of the bulk material items is analysed by a mechanical vision system. The sensor signals are converted in a processor to control commands which selectively trigger the transmission of a pulse to specific points of the flexible membrane, so the position of at least some bulk material items is changed in the selection zone and is brought into a desired positive alignment. These bulk material items with the desired alignment are selected and removed from the membrane by a robot.  
         [0011]     A feed device for the bulk material items to a robot according to WO,A1 00/69240 comprises a selection zone of an apparatus which is accessible to the robot for randomly changing the position and/or alignment and an apparatus with a parts recirculation element for recirculating the bulk material items which are not grasped. The apparatus for randomly changing the position and/or alignment of the bulk material items is a vibration platform simultaneously designed as a selection zone. In a first relative position of the recirculation element and vibration platform, the platform can be loaded with bulk material items of the recirculation element. In a second relative position, the bulk material items which drop from the vibration platform can be caught by the recirculation element. During operation of the device for feeding bulk material items for a robot, at least six steps are carried out one after the other in a continuous endless process. In a first step, the vibration platform is loaded with bulk material items from the parts recirculation element. In a second step, bulk material items dropping from the vibration platform are caught by the recirculation element. In a third step, the position and/or alignment of the bulk material items on the vibration platform is randomly changed. In a fourth step, the position and alignment of the bulk material items is detected and the data transmitted to the robot, which in a fifth step grasps bulk material items in a favourable position and alignment and conveys them away. In a sixth step, the number of bulk material items remaining on the vibration platform is determined and depending on the result, returned to the first or second step.  
         [0012]     The object of the present invention is to provide a device and a method of which Improve and simplify the feeding of bulk material items from a store to a robot.  
       SUMMARY OF THE INVENTION  
       [0013]     The object is achieved according to the device of the present invention in that a one-piece oscillating conveyor surface is supported by an oscillating conveyor arm, which oscillating conveyor surface with first or with first and second means is supported so as to be horizontally displaceable in the x-direction or in the x- and y-direction and extends from a storage zone over a distribution zone to the front end of a selection zone for the bulk material items and projects freely, together with the oscillating conveyor arm, the storage, distribution and selection zone having an edge, and third means for generating the oscillating motion in the z-direction are connected to the oscillating conveyor arm. Special and further embodiments of the device according to the invention are set forth hereinbelow.  
         [0014]     The oscillating conveyor arm is substantially board-shaped and generally elongate in design, consists of an adequately mechanically rigid, resilient material, and can oscillate freely at one end in the region of the distribution and selection zone within the edge and thus throw up the bulk material items for realignment. The forward feed and a possible reverse transport of the bulk material items take place in that the one-piece oscillating conveyor surface which is supported by the oscillating conveyor arm can be moved with the first means linearly in the x-direction of the free end of the selection zone, or with first and second means in a planar manner in the x-direction of the front end of the selection zone, and in the y-direction perpendicularly thereto. In both cases, a targeted conveying direction is possible owing to corresponding means of the first or first and second means. The oscillating conveyor arm is generally rigidly mounted in the region of the storage zone, but, in the case of smaller systems, can also be displaceably mounted in the x- or x- and y-direction owing to the smaller mass of the oscillating conveyor arm and can be rigidly connected to the oscillating conveyor surface. In larger systems, an oscillating conveyor arm which is movable in the x- or x- and y-direction could lead to unreliable oscillations of the machine table because of the larger mass.  
         [0015]     A desired bending region is preferably formed in the oscillating conveyor arm between the storage and the distribution zone and this takes place owing to at least one transversely extending weakening groove and/or hole. A weakening groove is expediently arranged at the bottom, two weakening grooves can be arranged located at the bottom next to one another or one above the other, the latter only if the oscillating conveyor surface which is supported on the oscillating conveyor arm is sufficiently load-bearing in the region of the groove. More than two grooves are arranged correspondingly. Two or more holes can likewise be arranged next to, or one above the other, also in combination with grooves. The geometric cross-sectional shape of the grooves and holes is not of substantial significance. Instead of the formation of at least one groove and/or one hole, the oscillating conveyor arm can be designed to form a weakening line in two parts, the two parts being connected to at least one spring, preferably by way of one or more leaf springs, for example made of spring steel. The formation of a weakening line causes the oscillating conveyor arm to act practically like a hinge and to have a much lesser spring action. The spring constant of the oscillating conveyor arm with respect to this “axis of rotation” is determined in practice by the spring of a lifting cylinder for the excitation of oscillation in the z-direction.  
         [0016]     The first and second means acting in the x- and optionally also in the y-direction of the coordinate system on the oscillating conveyor surface, or on the oscillating conveyor arm, as well as the third means acting, preferably in a spring-mounted manner, on the oscillating conveyor arm, are in practice, for example, pneumatic or hydraulic lifting cylinders which are known per se with a piston and piston rod, but electrical linear or stepping motors can also be used. Because of the rapid working cycle in fractions of seconds, spindles with a rotor would be more problematic, for example.  
         [0017]     In the time span between detecting the position and alignment of the bulk material items in a favourable position and grasping by the robot, the oscillating conveyor surface must neither move in the x- nor y-direction, because otherwise the coordinates calculated by the processor on the basis of the sensor signals for grasping favourably arranged bulk material items would no longer be correct. Likewise, during this time period, the oscillating motion in the z-direction has to be stopped. This generally takes place with means damping the oscillating motion in the z-direction at the oscillating conveyor arm, expediently with a damping cylinder which is known per se, a rubber ball or a rubber bellows.  
         [0018]     A sensor for measuring the deflection and frequency of the oscillating conveyor arm is expediently arranged therebelow. From the measured values which are determined, the processor can calculate the inherent frequency of the oscillating conveyor arm with the components fastened thereto, and the amplitude for each position on the oscillating conveyor surface, and evaluate them for industrial processes. The inherent frequency of the oscillation in the z-direction is also influenced by the design of weakening grooves and/or holes in the desired bending region. The energy required to generate an oscillating motion can thus be reduced and the process be made more efficient than in a frequency other than the inherent frequency which is basically also possible.  
         [0019]     The front end edge of the selection zone, which ends the forward feed movement of the bulk material items, is preferably also designed so as to be automatically removable, in particular as a slide, door or flap.  
         [0020]     The front end edge of the storage zone can also similarly be expediently removed if a new batch of different bulk material items is to be fed. The oscillating conveyor surface can thus be rapidly and easily emptied, even automatically in all zones, including the store. The removable part of the edge is also expediently designed here as a slide, door or flap.  
         [0021]     To individualise the sliding and/or rolling resistance of the bulk material items, the oscillating conveyor surface can be replaced; it consists, for example of a polyamide. Furthermore, the oscillating conveyor surface can be roughened or textured in design or have a coating, in particular a woven or nonwoven fabric to change its static friction. On the other hand, the oscillating conveyor surface, apart from optimum static friction, also has to have low abrasion, in other words be as mechanically wear-resistant as possible.  
         [0022]     According to a special embodiment, the oscillating conveyor arm with the oscillating conveyor surface is designed to be transparent, at least in the region of the selection zone, and a backlight is arranged below this zone.  
         [0023]     The object is achieved according to the method of the present invention in that an oscillating motion is generated in the z-direction with a programmable amplitude which is continuously increasing in the x-direction, and therefore correspondingly increased speed and acceleration of the bulk material items, which oscillating motion takes place alternatingly or at least partially simultaneously and coordinated with a forward feed or reverse transport of the bulk material items in the x- or in the x- and y-direction, wherein, during the time period of a snapshot by the vision system until removal of bulk material items by the robot, all movements of the oscillating conveyor surface in the x- or in the x- and y-direction are stopped and the oscillating motions in the z-direction are damped or stopped. Special and further method variants are described hereinbelow.  
         [0024]     Owing to the oscillating amplitude of the oscillating conveyor arm increasing in the z-direction and the co-oscillating oscillating conveyor surface with correspondingly increased speed and acceleration of the bulk material items, the degree of reorganisation and individualisation in the direction of the front end of the selection zone also increases continuously and this has positive effects for the practical course of the method.  
         [0025]     The oscillating amplitude which is increasing in the x-direction is preferably generated by transmitting a programmable oscillating motion, in particular with a frequency of 5 to 30 Hz, to an oscillating conveyor arm which is freely projecting outside a storage zone and which is supporting the entire surface area of an oscillating conveyor surface. The one-piece oscillating conveyor surface according to the invention also allows the feeding of small and flat bulk material items which would jam or even disappear on transfer from one oscillating conveyor surface to another.  
         [0026]     The forward feed movement of the oscillating conveyor surface which is supported over the entire surface area by the oscillating conveyor arm or connected thereto, in the x- or in the x- and y-direction, and the corresponding reverse transport movement preferably take place with different acceleration. In the case of transport in the direction of the front end of the selection zone, the acceleration to the forward movement takes place so slowly that the bulk material items do not slide or only a little. The acceleration to the return transport movement, on the other hand, takes place so quickly in this transport direction that the bulk material items remain in place due to their inertia or only displace slightly. Both movements take place within fractions of seconds. In addition to the resulting forward feed direction, the bulk material on the oscillating conveyor surface is separated and distributed randomly in a random position owing to this rapid back and forth movement of the oscillating conveyor surface. A forward feed of a plurality of centimetres per second can thus be achieved, in the selection zone region, the bulk material items are present in an adequate number and adequately distributed for the gripper of the robot.  
         [0027]     If too many bulk material items should be in the selection zone, instead of a forward feed movement, a reverse movement can be achieved in that the slower movement in the x- or x- and y-direction takes place toward the storage zone, and the faster one toward the selection zone.  
         [0028]     A forward feed movement of the bulk material items can also be achieved in that a forward feed movement is jerkily interrupted and, because of the kinetic energy of the bulk material items, they are made to slide, for example by a hard stop, the reverse movement, on the other hand, is interrupted more slowly. Obviously, combinations of the two forward feed or reverse transport variants is also possible.  
         [0029]     All the movements of the oscillating conveyor surface in the x-, y- and/or z-direction are preferably controlled and coordinated by the processor, preferably according to signals of the camera or another sensor by way of the number, position and/or alignment of bulk material items in the selection zone. The forward feed or reverse transport of the bulk material items can be determined by movements of the oscillating conveyor surface in the x- or x- and y-direction, the random change of the alignment of these bulk material items, by the amplitude and frequency of the oscillating movement in the z-direction.  
         [0030]     Faulty bulk material items are generally not aligned even after numerous working cycles such that they are recognised and grasped by the robot with the same probability as the others, and this leads to an accumulation of the “poor” bulk material items in the region of the selection zone. When this proportion of “poor” bulk material items in the selection zone, established with the aid of signals from the camera or another sensor, is exceeded, the processor preferably controls an actuator for automatic opening of the front end edge, whereby all bulk material items located in the selection zone are removed, “good” and “poor”. Expediently, the front edge is only opened after reduction or stopping of the feeding of bulk material items from the storage zone, so the proportion of eliminated “good” bulk material items can be reduced.  
         [0031]     The advantages of the present invention can be summarised as follows: 
        Owing to the design of an oscillating conveyor arm freely projecting from the storage zone into the distribution and selection zone, with a substantially horizontal oscillating conveyor surface, oscillations in the z-direction can be generated with increasing amplitude and speed in the conveying direction. This simplifies and improves the continuous separation, and where necessary, disentanglement of the bulk material items in the conveying direction and increases the efficiency of the recombination to the new random alignment of the bulk material items.     The inherent frequency of the machine configuration, which is favourable in terms of energy, with the oscillating conveyor arm, can be used for the oscillating motion in the z-direction.     The one-part design of an oscillating conveyor surface which is also resting exchangeably on an oscillating conveyor arm allows efficient conveying of the bulk material items in the forward feed or reverse transport direction, the selection zone can be quickly supplied with new bulk material items or freed of excessive bulk material items.     The elimination of “poor” bulk material items from the selection zone can be carried out efficiently and with low losses of good bulk material items.     The device can be easily and automatically emptied of all bulk material items for the purpose of adaptation to another product or cleaning of the device.       
 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0037]     The invention will be described in more detail with the aid of embodiments shown in the drawings, which are also the subject of dependent claims.  
         [0038]     In the drawings:  
         [0039]      FIG. 1  shows a known device for feeding bulk material,  
         [0040]      FIG. 2  shows a plan view of the oscillating conveyor region of a device for feeding bulk material items in accordance with the present invention,  
         [0041]      FIG. 3  shows a cross-section along the line III-III of  FIG. 2 ,  
         [0042]      FIG. 4  shows a view of a plan of the region according to  FIG. 2 ,  
         [0043]      FIG. 5  shows a partial longitudinal section through an oscillating conveyor arm with an oscillating conveyor surface in the desired bending region,  
         [0044]      FIG. 6  shows a variant of  FIG. 5 ,  
         [0045]      FIG. 7  shows a further variant of  FIG. 5 ,  
         [0046]      FIG. 8  shows a cut-open view of a large device for feeding bulk material items,  
         [0047]      FIG. 8   a  shows a cross-section in the region of the oscillating conveyor arm,  
         [0048]      FIG. 9  shows a plan view of the region according to  FIG. 2 ,  
         [0049]      FIG. 10  shows a detailed embodiment of  FIG. 4 ,  
         [0050]      FIG. 11  shows a characterisation of a conveying principle in the starting position,  
         [0051]      FIG. 12  shows the arrangement according to  FIG. 11  after reaching a stop,  
         [0052]      FIG. 13  shows an arrangement according to  FIG. 11  after ending the reverse movement,  
         [0053]      FIG. 14  shows an excitation of the oscillating arm by continuous rectangular signals, and  
         [0054]      FIG. 15  shows a cut-open view of a small device for feeding bulk material items. 
     
    
     DETAILED DESCRIPTION  
       [0055]      FIG. 2  shows a plan view of a conveyor surface  16  with an edge  38 . The one-part conveyor surface  16  is functionally divided into a storage zone  40 , a distribution zone  42  and a selection zone  28 , the transition from zone to zone not being sharp, as shown by lines, but flowing within a region and without interruption on the surface, in particular between the distribution zone  42  and selection zone  28 . The conveying direction of the bulk material items  12  is designated by the space coordinate x. In particular in the case of a broad oscillating conveyor surface  16 , the forward feed of the bulk material items  12  may not only take place in the x-direction, but also in the x- and y-direction.  
         [0056]      FIG. 3  shows the arrangement of a freely projecting oscillating conveyor arm  44  in the rest position, which bears an easily replaceable layer  46  which forms the oscillating conveyor surface  16  and can be displaced relative to the oscillating arm  44 , at least in the x-direction, in the present case the layer is made of a polyamide plate. The oscillating conveyor arm  46  is board-shaped in design and consists of elastically resilient material with high mechanical strength, for example made of an aluminium plate of 100×30×1 cm. In the transition region from the storage to the distribution zone, a semi-cylindrical transverse groove is recessed on the underside, which groove leaves a material thickness of 0.3 cm at the weakest point. The oscillating conveyor arm  44  which is rigidly mounted at one end is arranged with play between a fixed edge  38  which projects at the bottom and top and thus protects the bulk material items  12  which are arranged on the oscillating conveyor surface  16  from being thrown off when the board-shaped oscillating conveyor arm  44  oscillates in the z-direction in the manner of a springboard.  
         [0057]     The oscillating conveyor arm  44  which is projecting a long way according to  FIG. 4 , with the displaceably supported oscillating conveyor surface  16 , can oscillate freely as shown by the double arrow z, with the oscillating conveyor surface co-oscillating. The oscillating conveyor arm is rigidly anchored in the region of the store  14  or the storage zone  40  ( FIG. 2 ), but can also be displaced in the x- or x- and z-direction according to a variant. In the transition from the storage zone  40  to the distribution zone  42  ( FIG. 2 ), as already mentioned, a bending zone  48  is formed, which can be more narrowly localised by suitable weakening measures in the form of grooves and/or holes and leaf springs connecting two parts ( FIG. 5  to  7 ).  
         [0058]     A level line  50  of the bulk material items  12  ( FIG. 2, 3 ) is drawn in in  FIG. 4 . This line shows the limitation of the bulk material items  12  which are lying one on top of the other in the store  14 ; it becomes lower toward the store exit, in the distribution zone  42 , the bulk material items  12  become more and more separated by the increasing oscillation amplitude and speed in the x-direction and are finally present individually in the selection zone  28 .  
         [0059]      FIG. 5  to  7  show the oscillating conveyor arm  44  with the oscillating conveyor surface  16 , which is displaceable thereon, in the region of a bending zone  48 . This bending zone  48  is better localised according to  FIG. 5  by a cross-sectional segment of a circle-shaped transverse groove  52  on the underside of the oscillating conveyor arm  44  and a hole  53 . According to  FIG. 6 , the oscillating conveyor arm  44  is designed in two parts and connected in the bending zone  48  to a leaf spring  51  made of spring steel and this leads to a weakening with a hinge effect. In  FIG. 7 , the localisation of the bending zone  48  takes place owing to three triangular transverse grooves  52  located at the bottom, which may be the same or different with respect to the cross-sectional region.  
         [0060]     The oscillating conveyor surface  16  according to  FIG. 5  is formed by a nonwoven fabric arranged on a plate  46  which can be displaced in the x-direction and according to  FIG. 6  by a displaceable plate  46  with transversely and/or diagonally extending millings  55 , which can also extend in a fluted manner.  FIG. 7  shows the oscillating conveyor surface  16  roughened in design. The plate-shaped layers  46  can be lifted off from the oscillating conveyor arm  44  and replaced, if necessary.  
         [0061]     According to a variant, not shown, for small systems, the oscillating conveyor arm  44  and the layer  46  for the oscillating conveyor surface  16  can be formed in one piece and consist of the same material, for example a polyamide.  
         [0062]     A device which is shown in  FIG. 8  for feeding bulk material items  12  has an oscillating conveyor surface  16  which is supported over the entire surface region by an oscillating conveyor arm  44 , the oscillating conveyor surface  16  in turn comprising a storage zone  40 , distribution zone  42  and selection zone  28 . A CCD camera  26  or another sensor, for example radar or ultrasound, monitors the selection zone  28  and is connected to a processor  56  by way of an only partially indicated electrical conductor  54 , the processor processing the received signals and triggering the various actuators in a targeted manner. Collisions of the robot gripper with bulk material items  12  are also detected and reported; the processor  56  initiates suitable measures.  
         [0063]     The oscillating conveyor arm  44  with the oscillating conveyor surface  16  is rigidly mounted in a manner which is known per se in the storage zone  40  and projects freely over the distribution zone  42  and selection zone  28 . In the bending zone  48 , a cross-sectionally rectangular transverse groove  52  is recessed in the oscillating conveyor arm  44 .  
         [0064]     The first means  58  for displacing the oscillating conveyor arm  44  in the x-direction are designed as pneumatically or hydraulically actuated lifting cylinders  58 , with the piston rod exerting an impact or tensile force.  
         [0065]     Optional second means  60  are similarly designed; they push or pull the oscillating conveyor surface  16  in the y-direction. The two movements take place in a coordinated manner, simultaneously or one after the other.  
         [0066]     Third means  62 , also designed as pneumatic or hydraulic cylinders, set the free part of the oscillating conveyor arm  44  into an oscillating motion, preferably with the inherent frequency of the relevant machine configuration. The impact pulse of the piston rod is transmitted elastically by way of a spring  64 , the lifting movement is thus coupled in a less rigid manner. This spring  64  substantially determines the spring constant of the oscillating conveyor arm  44  with the oscillating conveyor surface  16 , in the case of weakening of the bending zone  48 , in particular in the case of pronounced weakening.  
         [0067]     A front end part  66  (reject gate) of the edge  38  adjacent to the selection zone  28  can be actuated by a vertically acting pneumatic or hydraulic cylinder  68 , in the present case by lifting. The selection zone can thus be easily cleaned, and the removed bulk material items  12  fall into a cleaning container  70 .  
         [0068]     The edge  38  is completely or practically completely severed in the region of the bending zone  48  by a cut  49 . The edge  38  with the oscillating conveyor arm  44  and the oscillating conveyor surface  16  can thus be bent off or angled off. According to a variant, the edge  38  consists of flexible material.  
         [0069]     In the case of  FIG. 8 , the selection zone  28  of the oscillating conveyor surface  16  and oscillating conveyor arm  44  are transparent in design. Below the oscillating conveyor arm  44  is arranged a backlight  72 , and this, in particular, facilitates recognition of the alignment of the bulk material parts  12 .  
         [0070]     Finally, a sensor  74  which monitors the effective deflection of the oscillating conveyor arm  44  and therefore of the oscillating conveyor surface  16  is arranged under the oscillating conveyor arm  44 . If the desired value for the amplitude of the oscillating motion in the z-direction is exceeded, the third cylinder  62  returns to the basic position and a damping means  76  ( FIG. 10 ) in the form of a damping cylinder, travels upwards and stops the oscillating conveyor arm  44  very quickly and brings it into a defined horizontal position. This sensor  74  is also used to automatically detect the inherent frequency for an existing machine configuration. The oscillating conveyor arm  44  is briefly excited on switching on, the processor  56  analyses the sensor signal and determines the specific inherent frequency.  
         [0071]     The raised edge  38  in the front end region of the storage zone  40  is also designed as a liftable part  78  (purge gate), which is actuated by means, not shown. After this part  78  of the store  14  has been lifted, a product change with other bulk material items  12  can also be carried out automatically.  
         [0072]     The robot  18  with oscillating arm and gripper tool is merely indicated; it is designed according to  FIG. 1 .  
         [0073]      FIG. 8   a  shows a variant of an oscillating conveyor arm  44  with side guides  38 , in the section at the level of the spring  64 . The oscillating conveyor surface  16  is guided laterally with play into corresponding recesses  39 .  
         [0074]      FIGS. 9 and 10  show  FIGS. 2 and 4  in more detail and, in  FIG. 9 , loaded with bulk material items. The bulk material items  12  lie one above the other in multiple layers in the storage zone  40 , in the store  14  at the beginning of the oscillating conveyor surface  16 , so that as many bulk material items  12  as possible can be stored. Depending on their design, the bulk material items  12  are not interlocked, or else are more or less interlocked. The previous or new bulk material items  12  are poured in from an external container  80  and this is shown by an arrow  82 . Emptying after the lifting of the part  78  of the edge  38  is characterised by arrow  88 , and the bulk material items  12  fall into the container  80 .  
         [0075]     The distribution zone  42  which ends at the detection range of the camera  26  ( FIG. 8 ) shown by dashed lines, or at the selection zone  28 , begins at the exit of the storage zone  40 . In this distribution region  42 , the bulk material items  12  are prepared for entry into the selection zone  28 ; the bulk material items  12  transfer into a single position and separate owing to the rapid forward and reverse movements of oscillating conveyor surface  16  in the x-direction and the amplitude and speed of the oscillation in the z-direction increasing in the direction of the selection zone  28 .  
         [0076]     The selection zone  28 , where the bulk material items  12  are arranged spaced apart from one another separately, begins after the distribution zone  42 . Bulk material items  12 ′ with a “good” position and alignment suitable for being grasped by the robot  18  ( FIG. 1, 8 ) are drawn in white, non-graspable, “poor” bulk material items  12 ″ in an unsuitable alignment are drawn in black. Once the good bulk material items  12 ′ have been gripped, the remaining “poor” bulk material items  12 ″ are realigned by oscillations in the z-direction; prior to this and/or simultaneously, new bulk material items  12  are pushed up by the conveyor system. The vision system signals to the feeder when the bulk material items are to be realigned by vertical vibrations. This process is characterised by the two arrows  86 .  
         [0077]      FIG. 10  indicates by dashed lines the level line  50  of the bulk material items  12 . The arrows  90  in the z-direction show that the amplitude A ( FIG. 14 ) of the oscillation of the oscillating conveyor arm  44  with the oscillating conveyor surface  16  increases in the direction of the front end  66  of the selection zone  28 . The arrows  92  in the x-direction show that a forward and a reverse movement of the oscillating conveyor arm  44  is possible. Arranged next to the third cylinder  62  for generating the oscillations in the z-direction is a damping element  76 , in the present case designed as a damping cylinder.  
         [0078]      FIG. 11  indicates the starting position for the transport of a bulk material item  12  in the x-direction. A bulk material item  12  lies with a weight F g  on the oscillating conveyor surface  16  of an oscillating conveyor arm  44 . The coefficient of friction of the bulk material item  12  compared to the oscillation conveyor surface  16  is μ 0 . To displace the bulk material item  12 , a frictional force F R  has to be overcome. In the first means  58  for transport in the x-direction, a cylinder, two stop faces  94 ,  96  limit the lift of the piston, which is transmitted to the oscillating conveyor arm  44  by way of a piston rod  98 . In the starting position, the piston of the cylinder  58  lies on the stop face  94 .  
         [0079]     From this starting position, the cylinder  58  accelerates at a maximum g*μ 0  (g=acceleration due to gravity) in the x-direction pointing away from the cylinder  58 . The piston travels at full speed onto the stop face  96 . During travel onto the stop face, the bulk material item  12  slips on the conveyor surface by x W , the kinetic energy being destroyed. The delay during impact is substantially greater than g*μ 0  ( FIG. 12 ). After impact, the cylinder accelerates at a substantially greater acceleration than g*μ 0  in the reverse direction and travels back to the stop  94 . Because of the high reverse acceleration, the bulk material item  12  is only minimally pulled back, owing to inertia, it slips on the oscillating conveyor surface  12  ( FIG. 13 ). A forward feed of Δx results per work cycle.  
         [0080]     By reversing the sequence, the bulk material item  12  can also obviously move in the reverse direction.  
         [0081]     The amplitude A of the oscillating conveyor arm  44  in the z-direction in the region of the sensor  74  ( FIG. 8 ) is plotted in meters (m) over the time t in milliseconds (msec) in  FIG. 14 . Excitation by the third means  62  ( FIG. 8 ) takes place at regular time intervals with a rectangular signal (R). The deflection takes place in the rhythm Δt of the previously detected inherent frequency. The amplitude A of the oscillation S increases after each excitation. On reaching the desired value, the excitation is reduced or at least temporarily dispensed with. An exceeding of the desired value can be corrected by the damping element  76  ( FIG. 10 ).  
         [0082]     The increase shown in  FIG. 14  of the oscillating amplitude A is produced at the same position. These oscillation amplitudes A change when they are measured with respect to the x-direction inside or outside this position. A similar increase in the oscillation amplitudes A are established when they, without or with the same excitation, are measured at various positions more and more removed from the storage zone  50  with respect to the x-direction.  
         [0083]      FIG. 15 , in contrast to  FIG. 8 , shows a small device  10  for feeding bulk material items  12 . The essential components, which are specified in the previous figures, are retained on a base plate  100 . The oscillating conveyor arm  44  and the oscillating conveyor surface  16  are rigidly connected to one another. A linear guide  102  on the base plate  100  guides a slide  104  which is displaced in the x-direction by the horizontal lifting cylinder  58 , the first means, and has an axis of rotation  106  for the oscillating conveyor arm  44 . The lifting cylinder  62 , the third means in the z-direction, engages the oscillating conveyor arm  44  in a non-resilient manner by way of a pin on the oscillating conveyor arm  44  and excites, with about a 1 mm lift, the oscillation at an amplitude increasing in the direction of the free end. In the present case, the spring constant is established by the design of the bending zone  48  with the transverse groove  52 . The oscillating conveyor arm can also be moved in the x-direction with constructional measures which are known per se.