APPARATUS FOR TRANSFERRING OBJECTS

Abstract: A conveying apparatus comprises an elongate beam (26), which supports a conveying means (31) and is vibrated by electromagnetic vibrators (16) operatively connected between the beam and an elongate support member (6). Each end of the support member is supported by a resilient mounting (7) and a reaction mass (15) is located on the support member at a position between the mountings. An electromagnetic vibrator is arranged between one of the resilient mountings and the reaction mass and another electromagnetic vibrator is arranged between the other resilient mounting and the reaction mass. The beam comprises two planar members (27, 28) arranged at right angles to one another, one member (27) serving to support the conveying means (31) and the other member (28) serving to support the armatures (24) of the electromagnetic vibrators.

Description: Apparatus for Transferring Objects This invention relates to the transfer of objects, and more particularly the invention is concerned with a conveyor apparatus in which the objects are transferred on a vibrating conveyor surface. An example of a conveyor of this type is disclosed in Applicant's GB Patent No. 2223998B which describes the conveyance of objects by a conveying surface having a multiplicity of extremely thin, short flexible fibres packed as an ultra high density pile in a backing. The fibres are inclined with respect to the backing so that when the surface is vibrated the objects are transferred in the direction of fibre inclination. This type of conveyor possesses soft handling characteristics and is particularly suitable for transferring nuclear fuel pellets where damage to the sides or corners of the pellets must be avoided or at least minimised. For efficient operation of the conveyor apparatus it is desirable that the beam or platform on which the conveying surface is supported vibrates in a linear direction and any tendency of the beam to rock is eliminated or at least minimised. Because of the hazardous characteristics of certain types of nuclear fuel pellets transferred by the conveyor apparatus, it is sometimes necessary to locate the apparatus within a shielded enclosure, such as a glovebox. Therefore, the conveyor apparatus should be compact, mechanically simple and should facilitate maintenance operations. According to the invention there is provided apparatus for transferring an object, said apparatus comprising a beam of elongate form, the beam supporting a conveying means on which the object is transferred, a base means, an elongate support member supported at each end thereof by resilient mounting means mounted on said base means, and vibrator means operatively connected between said support member and said beam for imparting vibrations to the beam, and wherein a reaction mass is supported by the said support member and is located thereon at a substantially intermediate position between said resilient mounting means. Preferably said vibrator means comprises first and second electromagnetic devices, said first electromagnetic device being arranged between one of said resilient mounting means and said reaction mass and the second electromagnetic device being arranged between the other resilient mounting means and the reaction mass. The beam may comprise first and second substantially planar members arranged substantially at right angles to one another, and wherein said first planar member supports the conveying means and extends over and adjacent to the reaction mass. Each electromagnetic device may comprise an armature and an induction coil, the armature being secured to said second planar member. Preferably the base means comprises a first plate lying in a first plane and the support member includes a second plate lying in a second plane arranged substantially at right angles to the first plane and wherein the reaction mass and the induction coil are secured to said second plate. Advantageously, the resilient mountings, the reaction mass and electromagnetic devices are substantially in alignment with one another. In a preferred embodiment the conveying means comprises a cushion element for supporting the object thereon, the cushion element comprising a multiplicity of fibres arranged at an inclined orientation with respect to the beam, whereupon vibration of said beam causes the object to move along the cushion element in the direction of fibre orientation. Embodiments of the invention will now be described with reference to the accompanying drawings, in which: Figure 1 is a cross-sectional side elevation on the line I-I in Figure 2 of a conveyor unit, shown foreshortened, according to a preferred aspect of the invention; Figure 2 is a plan view of the conveyor unit shown in Figure 1 with parts omitted for clarity; Figure 3 is a cross-sectional end view of the conveyor unit on a line III-III in Figure 1; Figure 4 is a cross-sectional end view on a line IV-IV in Figure 1, and Figure 5 is a partial plan view showing an electromagnetic actuator for imparting vibrations to the conveyor unit. Referring now to the drawings, a conveyor unit 1 is shown and comprises an elongate base plate 2 of rectangular cross-section. Each end of the base plate 2 is secured to support means 3 by two clamping screws 4. Appropriate adjustment of four jacking screws 5, two at each end of the base plate 2, enables the conveyor unit 1 to be levelled. An elongate reaction mass support member 6 is supported at each end by two vibration isolation mountings 7. Each mounting 7 incorporates a resilient rubber bush and is supported on the base plate 2. The support member 6 comprises a vertical plate 8 and transversely arranged angle bars 9 welded to each end surface of the plate 8. Each of the angle bars 9 comprises a horizontal member 10 which is located so that the upper horizontal surface thereof is above the horizontal centre line of the vertical plate 8. The under surface of the horizontal member 10 is machined to seat the upper surfaces of the mountings 7. As seen in Figure 3, the angle bars 9 are secured to the mountings 7 by dome-head screws 11, each of which passes through the centre of the mounting and is screwed into a mounting plate 12. A clamping device 13 secures the mounting plate 12 to the base plate 2. Fixed by two screws 14 to the vertical plate 8 at a position mid-way between the two mountings 7 is a reaction mass .15. Alternatively, the reaction mass 15 may be integrally formed with the support member 6. Arranged on each side of the reaction mass 15 is an electromagnetic vibration actuator 16. As seen in Figures 4 and 5, each electromagnetic actuator 16 comprises a mounting plate 17, secured to the vertical plate 8 by a done-head screw 18, and a support plate 19. Two resilient cantilever springs 20 extend between each mounting plate 17 and support plate 19 and are attached thereto by respective clamping bars 21, 22 secured by screws. An electromagnetic induction coil 23 is mounted on the mounting plate 17 and a laminated armature 24 extends from the support plate 19 in a position such as to define a required air gap between the coil 23 and the armature in the de-energised state of the coil and in the stationary position of the support plate 19. A beam 26, having a length greater than that of the base plate 2, is in the form of an elongate angle bar. The beam has horizontal and vertical planar members 27, 28 respectively, the latter being attached to the support plate 19 of each of the electromagnetic actuators 16 by means of a dome-head screw 29. Interposed between the vertical member 28 and the support plate is a packing piece 30. The horizontal member 27 extends over and in close proximity to the reaction mass 15 and the two electromagnetic devices 16. Secured to and extending along the upper surface of the beam 26 is a conveyor means 31. Typically, the conveyor means 31 comprises two side plates 32, 33 which carry a shallow v-shaped support plate 34. On the upper surface of the support plate 34 is a cushion element 35 upon which objects, for example, a nuclear fuel pellet 36, can be transferred. The cushion element 35 comprises a multiplicity of extremely fine synthetic fibres, for example, nylon 66, set in a glass fibre reinforced vinyl base layer. Preferably the fibres are packed to form an ultra high density pile in the base at an angle of inclination with respect to the beam 26 of between 70° and 80°. The packing density of the fibres is of the order of 80 x 10 fibres per square metre, and each fibre is between 43 to 45 microns thick and projects up to 2.5 mm above the base layer. The cushion element 35 may be secured to the support plate 34 by a suitable adhesive, or by use of a magnetic strip attached to the support plate and having an adhesive backing to which the cushion element can be attached. It will be apparent that the conveyor means 31 could take other forms. For example, the cushion element 35 may lie in a horizontal plane and extend over substantially the entire surface of the horizontal member 27 of the beam 26. By arranging the horizontal member 27 of the beam 26 to be in close proximity to the reaction mass 15 and attaching the vertical member 28 to the electromagnetic actuators 16 enables the distance between the centre of gravity of the beam and the conveyor means 31 and the centre of gravity of the reaction mass to be kept to a minimum. In use of the conveyor unit 1, the electromagnetic actuators 16 are energised by an electrical supply of half-wave alternating current. This current causes the armature 24 to be attracted to the induction coil 23 against the tension of the springs 20 during the positive half cycle of the electric current, with a consequent reduction in the air gap between the induction coil 23 and the armature 24. During the negative half cycle when no current exists, since it has been half-wave rectified, the armature 24 returns under tension in the springs 20 to a point where the air gap has increased from that existing at the de-energisation position. The movement of the armature 24 is repeated during the next half cycles of the electric current and causes vibration of the beam 26. Because of the inclination of the fibres in the cushion element 35 the fuel pellet 36 is transferred along the cushion element 35 during the positive half cycle of the electric current. During the return motion of the beam 26 the fibres of the cushion element slide under the fuel pellet 36. Suitably, the frequency of the electromagnetic actuators 16 may be between 50 and 100 Hz with, for example, a vertical peak-to-trough displacement of 0.5 mm. The vibration isolating mountings 7 effectively minimise the transmission of vibrations to the support means 3 so that surrounding equipment is not adversely affected. By including a secondary vibration isolation mounting for the sub-plate 2, the transmission of vibrations to the support means 3 can be almost eliminated. The mass ratio between the reaction mass 15 and the combined mass of the beam 26 and the conveyor means 31 is preferably 5 : 1 or less. Where high speed conveyance of objects is not required it is possible with the compact configuration of the conveyor apparatus in accordance with this invention to operate with a mass ratio as low as 3 : 1. An important feature of the conveyor unit design is that the distance between the centre of gravity of the beam 26 and the conveyor means 31 and the centre of gravity of the reaction mass 15 is minimised. This feature reduces any tendency of the beam 26 to rock as it vibrates and, in addition, contributes to achieving a compact conveyor unit . It will be appreciated that rocking of the beam is undesirable since this tendency introduces a vertical element into the vibration that would need to be absorbed by the vibration isolation mountings 7. Advantageously, the reaction mass 15, electromagnetic actuators 16 and vibration isolation mountings 7 are arranged substantially in alignment. This configuration helps to achieve a compact arrangement and the desired vibration characteristics. Access to the electromagnetic actuators 16 for maintenance purposes is readily achieved by simply unscrewing the two dome-head screws 29 and then removing the beam 26. The conveyor unit 1 may form a module in a series of similar units so that the cushion elements 35 form a continuous length of conveying surface. If a conveyor unit becomes defective for any reason, it can be removed from the supports 3 and replaced by a new unit. The soft handling characteristics provided by the cushion elements have particular advantage for transporting a wide variety of relatively light objects with fragile surfaces. Thus, the conveyor unit is particularly suitable for use in transferring nuclear fuel pellets where damage to the sides or corners of the pellets must be avoided or at least minimised.

Claims: Claims 1. Apparatus for transferring an object comprising a beam of elongate form, the beam supporting a conveying means on which the object is transferred, a base means, an elongate support member supported at each end thereof by resilient mounting means mounted on said base means, and vibrator means operatively connected between said support member and said beam for imparting vibrations to the beam, and wherein a reaction mass is supported by the said support member and is located thereon at a substantially intermediate position between said resilient mounting means. 2. Apparatus according to Claim 1, wherein the vibrator means comprises first and second electromagnetic devices, said first electromagnetic device being arranged between one of said resilient mounting means and said reaction mass and the second electromagnetic device being arranged between the other resilient mounting means and the reaction mass. 3. Apparatus according to Claim 2, wherein the beam comprises first and second planar members arranged substantially at right angles to one another, and wherein said first planar member supports the conveying means and extends over and adjacent to the reaction mass. 4. Apparatus according to Claim 3, wherein the electromagnetic device comprises an armature and an induction coil, the armature being secured to said second planar member. 5. Apparatus according to Claim 3 or 4 , wherein the base means comprises a first plate lying in a first plane and the support member includes a second plate lying in a second plane arranged substantially at right angles to the first plane and wherein the reaction mass and the induction coil are secured to said second plate. 6. Apparatus according to any one of Claims 2 to 5, wherein the resilient mountings, the reaction mass and the electromagnetic devices are arranged substantially in alignment with one another. 7. Apparatus according to any one of the preceding Claims, wherein the conveying means comprises a cushion element for supporting the object thereon, the cushion element comprises a multiplicity of fibres at an inclined orientation with respect to the beam, whereupon vibration of said beam causes the object to move along the cushion element in the direction of fibre orientation.

Inventors: GLENVILLE REGINALD PAUL, GLENVILLE, REGINALD, PAUL
Applicants: BRITISH NUCLEAR FUELS PLC, GLENVILLE REGINALD PAUL, GLENVILLE, REGINALD, PAUL
Application year: 1996
Main classification: B65G27
IPC codes: B65G27