Patent Number: 050193260
Section: summary

BACKGROUND OF THE INVENTION 1. Field of the Invention The field of the present invention relates to a mechanical apparatus for handling pellets and the like, as well as examining the external appearance of the handled material. 2. Prior Art In general, pellets to be loaded into nuclear fuel rods are manufactured by molding green compacts of uranium dioxide and similar nuclear fuel powders into a cylindrical form, then sintering. Because defects may develop on the surface of the pellets during the manufacturing process, it is necessary that they be inspected. In the past, inspection of such pellets has been carried out by visual examination by inspection personnel. During this inspection, pellets with surface flaws are removed. With such a method, however, it is necessary that each sintered pellet be individually examined in order to obtain reliable results. Such an inspection method is quite laborious and considerably inefficient, and furthermore, places considerable demands on the inspection personnel. With this in mind, various types of imaging equipment for examining the surfaces of the pellets have been proposed. With such methods, however, elaborate pellet handling devices are required to handle the pellets. Thus visualization and throughput of the pellets at a sufficiently high rate has not yet been achieved. SUMMARY OF THE INVENTION With the above described limitations of the prior art in mind, an object of the present invention is to provide an apparatus which can rapidly and smoothly rotate a pellet or the like about its axis while otherwise maintaining it in a fixed position, then eject the handled object. Furthermore, it is another object of the present invention to provide an apparatus which can inspect the surface of the pellet or other object while it is rapidly handled. Further objects of the present invention will become clear through the description of the preferred embodiments. To achieve the above objectives, the present invention provides a pellet handling apparatus equipped successively with a cylindrical roller and a slotted transfer roller which can freely rotate in the same direction. Furthermore, along with a pellet supply unit which is provided to supply pellets between the above mentioned cylindrical roller and the slotted transfer roller, a pellet transfer unit is provided at the above mentioned slotted transfer roller. Similarly, the present invention provides an external inspection apparatus which includes a circumferential surface inspection unit added to the above described assembly by which means the external circumferential surface of a pellet placed between the above mentioned cylindrical roller and slotted transfer roller may be inspected. Also included is a defective pellet discard unit as part of the above mentioned pellet discard unit by which means pellets judged to be defective by the above mentioned circumferential surface inspection unit are discharged. Moreover, the present invention as recited in claim 3 provides an external inspection apparatus in which a direction switching assembly is included on the first part of the above mentioned pellet supply unit, whereby the direction in which the pellet is conveyed is switched from the axial direction of the pellet to a direction perpendicular thereto. Also provided is a drying--rough sorting apparatus which dries and sorts the pellets after the above described switch in direction, and on this drying--rough sorting apparatus, an end surface inspection unit by which means the ends of the sorted pellets may be inspected. On the last portion of the above mentioned pellet discard unit, a pellet gathering assembly is provided to collect the pellets. The above described direction switching assembly includes a buffer tray upon which the pellets are placed arranged along their axes in multiple columns, as well as a pickup unit by which means the pellets on the buffer tray are grasped on their circumferential surface and conveyed. The above described drying--rough sorting apparatus includes a revolving conveyer unit by which means the pellets are rotated about their longitudinal axes while they are conveyed in a direction perpendicular to their longitudinal axes and a drying unit mounted on the revolving conveyer unit, and mounted on the rear portion of the drying unit, a rough sorting apparatus by which means the circumferential surfaces of the pellets are imaged from above and sorted on the basis of said image. The above mentioned end surface inspection unit has an intermittently rotating conveyer disk with pellet receiving grooves in its outer circumferential surface. While received in the grooves, each end of each pellet is independently imaged, and on the basis of these images, the pellets are judged as acceptable or not acceptable by means of an end surface evaluation unit. The end surface inspection unit also includes a defective pellet discard unit by which means pellets judged defective by the end surface evaluation unit are discarded. The above mentioned pellet gathering assembly includes a pellet placing unit which places and lines up a plurality of the pellets aligned in a direction perpendicular to their longitudinal axes. The pellet gathering assembly also includes an end surface pickup unit by which means the placed and aligned pellets are grasped by their end surfaces and conveyed. For the pellet handling equipment of the present invention as claimed in claim 1, the pellets are supplied from the pellet supply unit and are placed between the cylindrical roller and the slotted transfer roller which rotate in the same direction, and the pellets are thereby caused to revolve in this position. When the slotted transfer roller rotates to the position where its transfer slot meets the pellet, the pellet is received by the slot. For the external inspection apparatus of the present invention as claimed in claim 2, the pellets are supplied from the pellet supply unit and are placed between the cylindrical roller and the slotted transfer roller which rotate in the same direction, and while the pellets revolve in this position, their circumferential surfaces are inspected by the circumferential surface inspection unit. Those pellets judged to be defective are then discarded by the pellet discard unit. For the external inspection apparatus of the present invention as claimed in claim 3, through the action of a direction switching apparatus, the direction in which the pellets are conveyed is switched from the axial direction of the pellets to a direction perpendicular to the circumferential surface of the pellets. The pellets are then dried and rough sorted by means of the drying--rough sorting apparatus, after which the ends of the sorted pellets are inspected by means of the end surface inspection unit. The pellets are then placed between the cylindrical roller and the slotted transfer roller which rotate in the same direction, and while the pellets revolve in this position, their circumferential surfaces are inspected by the circumferential surface inspection unit. Those pellets judged to be defective are then discarded by the pellet discard unit while those judged as suitable collected by the pellet gathering assembly. With the above mentioned direction switching apparatus, the pellets are aligned in multiple columns on buffer trays, and through the action of a circumferential surface pickup unit, the pellets on the buffer tray, one from each column, are grasped on their circumferential surface and conveyed. The previously mentioned drying--rough sorting apparatus includes a revolving conveyer unit over which the pellets proceed in a direction perpendicular to their longitudinal axes while rotating about their longitudinal axes. As the pellets are conveyed, they are dried by the drying unit, and then through the action of the rough sorting unit, their circumferential surfaces are imaged. On the basis of the obtained images, the pellets are sorted as acceptable and defective. In the previously described end surface inspection unit, the pellets are received in grooves in the intermittently rotating conveyer disk, and while received in the grooves, the ends of the pellets are imaged, and on the basis of the images, the pellets are judged as acceptable or not acceptable by means of an end surface evaluation unit. Those pellets judged defective are then discarded by a defective pellet discard unit. With the above mentioned pellet gathering, the pellets are lined up in a direction perpendicular to their longitudinal axes by the pellet placing unit, after which a plurality of the pellets are grasped by means of the end surface pickup unit by their end surfaces and conveyed.