PALLETS

Abstract: A pallet (l2) for an automated transportation apparatus includes resilient restraining means (l4) protruding from an upper load carrying surface (l3) to prevent sliding movement of an article on the surface.

Description: This invention relates to pallets and is particularly concerned with pallets for transporting articles in automated transportation apparatus. To avoid confusion the use of the term article in this specification is intended to include an article itself or an article holding device which is sometimes used to enable unstable articles to be transported. EP-A-0128999 discloses a prior transportation system and pallet and is concerned particularly with constructional features of the pallet which has a generally planar upper load carrying surface. One of the problems with such a pallet is that accelerations resulting from the stop-start nature of pallet movement cause instability especially in respect of lateral sliding movement of the articles on the pallets, even in the case of normally stable articles. The problem is not entirely overcome by the use of holding devices for inherently unstable articles since the holding device itself is of course subject to the accelerations so that it too is unstable at least as far as lateral sliding movements are concerned. Another problem concerns the need to cater for different sized articles and for articles having a wide variety of different shapes. A pallet for transporting articles in an automated transportation apparatus according to the precharacterising part of claim 1 is disclosed in the DE-C-3444320 and includes a load carrying plate with a plurality of circular holes housing axially movable pins each having an inner end in contact with a sheet of compressible foam material urging the pins to a protruding position. Individual pins within surface areas of articles on the load carrying plate are depressed to a position substantially flush with the surface and articles are thus restrained at least within certain limits by adjacent protruding pins. The use of circular pins in the prior device provides line contact only with articles on the plate and consequently may provide little lateral restraint especially in respect of small articles. Accordingly a pallet for transporting articles in an automated transportation apparatus includes a plurality of resilient restraining means protruding from an upper load carrying surface and adapted to be depressed to a position substantially flush with the surface by an article placed on the surface whereby the article is restrained against sliding movement by protruding restraining means outside the surface area of the article, characterised in that said restraining means are arranged in a rectangular grid pattern with sides of each grid defined by individual elongated restraining bars with intermediate bars common to adjacent grid areas, slots disposed in the surface for slidably locating the restraining bars and spring means within the slots and urging the restraining bars to the protruding position. The ends of individual restraining bars may be pointed in plan so as to interlock at the corners of the grid. The slots in cross section may have an inverted T-shape and the restraining bars may have a T-shape arranged with the enlarged portion located in the lowermost portion of the slot so as to limit protrusion of an upper portion of the restraining bar to a predetermined amount. The spring means may be located between facing surfaces of the restraining bar enlarged portion and an adjacent surface of a pallet base plate and the slots may be formed between edges of a plurality of rectangular blocks attached to the pallet base plate. The invention will now be described by way of example only and with reference to the accompanying drawings in which, Figure 1 is a schematic plan view of a pallet for transporting articles in an automated transportation apparatus, Figure 2 is a fragmentary view of the part of the pallet of Figure 1 enclosed within area A of Figure 1 on an enlarged scale, and Figure 3 is a fragmentary sectioned view taken along lines B-B of Figure 2. A pallet 12 for use in an automated transportation apparatus has an upper load carrying surface 13 provided with restraining means comprising a plurality of individual spring loaded restraining bars 14 arranged in a grid pattern. The restraining bars 14 normally protrude about 2.0mm above the surface 13 to provide lateral restraint against sliding movement of an article on the load carrying surface 13. As schematically illustrated in Figure 1, a small generally stable article 15 can be located between the restraining bars 14 of a single square of the grid whereas a larger generally stable article 16 will depress the restraining bars 14 lying within its surface area (indicated by broken lines in Figure 1) to a position substantially flush with the surface 13 so that lateral restraint is still provided by adjacent protruding restraining bars 14 surrounding the component 16 externally of its surface area. In the case of unstable articles requiring holding devices such as apertured blocks (not shown) it will be apparent that the devices can be sized to cover one or more of the grid squares so that again lateral restraint to prevent sliding is provided by the protruding restraining bars 14 surrounding the holding device. Similarly, also, restraining bars 14 lying within the surface area of the holding device will be depressed flush with the surface 13. Referring now to Figures 2 and 3 it will be seen that load carrying surface 13 of pallet 12 is provided by an upper surface of a plurality of square blocks 17 secured to a base plate 18 by a centrally located bolt The edges of the blocks 17 are recessed at 20 in order to form in combination with adjacent blocks 17 or shaped edge plate 21, inverted T-shaped slots 22 arranged in a grid pattern comprising a plurality of equally sized squares. The edge plates 21 are of generally inverted 'L' shape and are bolted to the edges of the base plate 18 to form the slot 22 that defines the outer extremity of the grid. The restraining bars 14 are located in the T-shaped slots 22. As shown in Figure 3, the restraining bars 14 in cross section are also T-shaped and arranged with the enlarged portion 14 a located in the lowermost portion of the slot 22 with freedom for vertical sliding movement and an upper portion 14 b which extends through the slot 22 and is capable of protruding from the upper surface 13 by about 2.00mm as indicated at 26. Two compression springs 23 are located in recesses 24 in the lowermost surface of the restraining bars 14 and act against the facing surface of the base plate 18 to normally retain the retaining bar 14 with the upper end 14 b protruding above surface 13 by the aforementioned predetermined amount. As shown in Figure 2, each square of the grid is defined by four individual spring loaded restraining bars 14, with intermediate bars 14 being common to adjacent grid squares. The ends of all of the restraining bars 14 are pointed as at 14 c so as to interlock neatly at the corners of the grid squares. The grid arrangement is well suited to identifying pallet areas for computer control and, by ensuring that the restraining bars 14 are made to be easily distinguishable from the surface 13 e.g. by a black anodic treatment, a good image is presented for computer vision systems. This means that during operation a controlling computer system can easily identify a required grid area and can carry out a visual analysis of that area. Attachment means (not shown) are provided on the base plate 18 in order to attach the pallet 12 to a power driven transportation apparatus such as a conveyor system. One particular pallet construction consists of a one hundred square (i.e. 10 x 10 matrix) grid with a nominal size for each grid square of 50mm x 50mm in a pallet of 500mm x 500mm overall size. Thus, this invention provides, in an automated transportation apparatus, a pallet which provides automatic lateral restraint for a wide variety of articles or article holding devices having widely differing shapes and sizes, thereby resulting in an extremely flexible transportation apparatus. Whilst one embodiment of the invention has been described and illustrated it will be understood that modifications may be made without departing from the scope of the invention as defined by the appended claims. For example, the two compression springs 23 associated with each restraining bar 14 may be replaced by other suitable means such as a single leaf spring or by an insert of resilient material such as rubber; and the bolts 19 may be inserted through the base plate 18 so as to provide an uninterrupted upper load carrying surface 13.

Claims: A pallet for transporting articles in an automated transportation apparatus including a plurality of resilient restraining means protruding from an upper load carrying surface and adapted to be depressed to a position substantially flush with the surface by an article placed on the surface whereby the article is restrained against sliding movement by protruding restraining means outside the surface area of the article, characterised in that said restraining means are arranged in a rectangular grid pattern with the sides of each grid defined by individual elongated restraining bars (14) with intermediate bars common to adjacent grid areas, slots (22) are disposed in the surface for slidably locating the retraining bars and spring means (23) within the slots for urging the restraining bars to the protruding position. A pallet as claimed in Claim 1, further characterised in that the ends of individual restraining bars (14) are pointed (14 c ) in plan so as to interlock at the corners of the grid. A pallet as claimed in Claim 1 or Claim 2, further characterised in that said slots (22) in cross section have an inverted T-shape and said restraining bars have a T-shape arranged with the enlarged portion (14 a ) located in the lowermost portion of said slot so as to limit protrusion of an upper portion (14 b ) of the restraining bar to a predetermined amount. A pallet as claimed in Claim 3, further characterised in that said spring means (23) is located between facing surfaces of said restraining bar enlarged portion (14 a ) and an adjacent surface of a pallet base plate (18). A pallet as claimed in Claim 4, further characterised in that said slots (22) are formed between edges of a plurality of rectangular blocks (17) attached to the pallet base plate (18).

Inventors: BALLARD, RICHARD LESLIE, GODDARD-WATTS, MARK, HALLETT, DAVID NORMAN
Applicants: WESTLAND GROUP PLC
Application year: 1987
Main classification: B23Q1
IPC codes: B65D19, B23Q1, B25B11