APPARATUS FOR SEPARATING STACKED LIDS

Abstract: A method and apparatus for de-stacking of stacked cardboard lids (1) having a pressed rim bead. The lids (1) in a magazine (2) are lifted, preferably by a suction device (11). Superfluous lids (1a) accidentally carried up with the uppermost lid (1) are separated by deforming the rim bead. In one apparatus the deformation is carried out by a set of resiliently mounted conical rollers (23).

Description: SEPARATING STACKED CARDBOARD LIDS This invention relates to the separation of lids having beaded rims and more particularly large round lids pressed from cardboard, for example of the type used with drum-shaped bulk containers for detergent powders. While deep-drawn plastics lids for small containers, for example for foods, can be formed with projections, separations and similar de-nesting means, shaping of this kind is not possible in the case of rim beading which is pressed, crimped or otherwise formed from board, since shaping of the board causes additional irregularities in the two external surfaces of the board as well as dimensional variations. This results in the rim beads of stacked lids becoming wedged together. Manual separation of lids has hitherto been necessary prior to lids being placed mechanically on the containers to be closed. The object of the present invention is to make mechanical de-stacking and individual separation of lids possible. German Gebrauchmuster 1785233 describes a method and apparatus for separating material in the form of leaves or foils stored in a magazine, using a vacuum device for lifting the leaves past a constriction in the magazine. US Patent No 3,275,189 describes an apparatus for separating nested pocketed trays by deforming the trays under vacuum, and US Patent No 3,322,301 describes a similar device. None of these prior art devices are effective in the separation of lids having beaded rims with which the present invention is concerned. It has now been found that wedged lids can be separated by deformation, that is to say light radial compression of at least one zone of the external rim bead if said deformation is applied in a zone extending around part of the lid periphery. According to the first aspect of the present invention there is provided a method of separating stacked rounded lids formed with rim beading, particularly lids formed from board, characterised in that each uppermost lid is withdrawn from the stack by gripping of the flat central portion and the rim bead in which a second lid may be wedged is temporarily deformed in a zone or zones extending round the periphery of the lid. According to the second aspect of the invention there is provided an apparatus for carrying out the method of claim 1 comprising a magazine for stacked lids and a suction plate movable in the direction of the axis of the magazine for withdrawing each uppermost lid from the magazine, characterised in that during lifting the suction plate is rotatably driven on reaching a certain position and in this position there is arranged laterally of the suction plate at least one pressure roll pivotable against the rim beads of lifted lids for temporary deformation thereof. Thus, the deformation can be achieved for example by pressing one or more pressure rolls against the outside of the rim bead in order to cause localised deformation and at the same time rotating the lid between the rolls. Alternatively, the lid may be stationary and the rolls rotated around the lid. Localised compression of the rim bead causes outward deformation in advance of the roll so as to release the hold of the first lid on the second one. At the same time the wedged rim bead of the second lid is displaced from the deformed rim bead. This local deformation of the rim bead is temporary only and the applied force is insufficient to damage the rim bead. Advantageously, lids are removed from the stack vertically or diagonally upwards, being gripped by a suction means or suction plate, the open side of the rim bead being lowermost. Wedged lids lifted simultaneously fall back onto the stack when the hold between lids is released. The lid magazine can be inclined, the lids being removed by the suction means upwardly and at an angle of 10-30 to the horizontal. The rim beading of lids pressed from board is not usually accurately circular. For this reason and because of variations in lid diameter, magazines must have relatively large lateral tolerances. Thus, central gripping of each lid is impossible. Suction means and/or pressure rolls are therefore resiliently mounted or adapted to compensate for eccentric gripping of lids and to prevent damage to the rim bead by excessive roll pressure. Lid diameters are generally between about 20 and 35 cm and board is about 1 mm thick. The rim bead, for example, projects about 1 to 1.3 cm above the top or outside surface of the flat central lid portion and is curved with radius of approximately 0.5 to 0.8 cm. This curvature is continuous with an outside rim bead surface having approximately the shape of a conical frustum and extending about 0.5 cm below the lower or inside surface of the central lid portion. In vertical section the outside rim bead surface is at an angle of from 93 to 1000 to the central lid portion. In the plane of the central lid portion the groove formed by the rim bead is about 1.5 cm wide. These and similar groove configurations and complementary external shapes of the rim bead necessary to fit the lid to the container cause the lids when stacked to wedge together, contrary to what is required, either around the entire periphery or around parts thereof. In a preferred embodiment the pressure rolls are pressed against the rim bead such that the line of contact between the periphery of the rolls and the outside bead surface defines approximately the surface of a conical frustum. Thus the pressure rolls can be conical to complement the conicity of the outside bead surface and rotatable about axes parallel to the direction of travel of the suction means. More than one pressure roll may be arranged in one plane within the apparatus laterally of the path of travel of lids when gripped by their upper surfaces by the suction means. Resilient and movable suspension of the suction means, for example by means of a universal joint or other joint means permitting lateral displacement of the suction means at right angles to the direction of lid travel with minimal bearing friction, is advantageous for compensating eccentric gripping of lids. The lids which in this part of the lift stroke are rotated by the suction means are centered together with the suction means by the rolls and are locally deformed. It is also possible for the suction means, normally made of rubber or of a similar flexible material, to be adapted to have a resilient zone at right angles to the direction of lid travel for providing at least temporary displacement of the gripping surface of the suction means on the lid and thus of the lid itself as lateral pressure is applied by one pressure roll or as the result of the centering action of several rolls spaced regularly about the periphery of lid and elastically pressed against the lid. Compensation of eccentricity can also be provided by arranging the pressure rolls in a ring or cage mounted resiliently, that is to say adapted for lateral movement in one plane. In a preferred embodiment for non-damaging handling of lids, the individual rolls are simultaneously pivoted from the side to bear with limited force against the rim bead of the lid. Means acting to limit the force of compression such as springs, pneumatic cylinders and the like prevent damage which might otherwise be caused by pronounced eccentricity or by variations in the dimensions and shape of the rim bead. Additional resilient suspension and/or construction of the suction means is advantageous. In such a construction having three conical rolls pivotable against the lid one rotation of the lid will generally suffice to release the hold between a first lid and a second simultaneously lifted lid. The use of a sensor device to detect whether one or more lids are held by the suction means is possible. The signal from said sensor device can cause rotation of the suction means to continue and the rolls to be pivoted into position. If only one lid is lifted from the stack the signal from the sensor device causes rotation of the suction means not to be actuated and the rolls not to be pivoted into position. Instead of conical rolls, rolls pressing laterally against the lower edge of the rim bead and co-operating with a second roll lying against the curvature of the rim bead may also be used. The invention will now be described in further detail by reference to the accompanying schematic drawings which show particular embodiments of the invention and in which Figure 1 shows an apparatus for lifting and separating individual lids, Figure 2 shows a conical roll pressing against the rim bead of a lid, Figure 3 shows an alternative arrangement of the pressure rolls; Figure 4 shows an apparatus with an inclined magazine. In Figure 1 a magazine (2) is shown in which lids (1) lie in a vertical stack on plate (3) which is raised to bring the uppermost lid approximately to a predetermined position. A suction plate (11) is mounted on a lower rod (12) connected through the universal joint (13) with an upper rod (14). To prevent undesired oscillations of the suction plate the lower rod (12) can be elastically held in a central position by springs, not shown. Rod (14) is rotatably mounted within a beam (15) which is upwardly movable by means of sliding guides (16) on rails (17), upward movement being obtained by a lifting means (18). The latter is arranged on an arm (19) which is rotatable about a column (20). The rod (14) can be driven by a motor (21) and driving means (22). In use the suction plate (11) is lowered to the indicated position (lla). By means of a vacuum the uppermost lid (1) is gripped by the flat central portion. The suction plate (11) is then raised to the position shown in full lines. A number of other lids, whose rim beads have wedged together in the stack, may be lifted simultaneously. Whilst in this position the suction plate (11) is rotated by means of the motor (12) and the rim bead of the lifted lid is locally deformed by the rolls (23), the zone of deformation extending around the lid periphery as a result of rotation of the lid (1). The hold between lids is thus released and undesired simultaneously lifted lids (la) fall back onto the stack. he suction plate (11) is raised still further and by rotation of arm (19) is pivoted laterally for example into position (llb). In this position vacuum is interrupted and the lid may be conveyed by means of a suitable chute, not shown, for positioning on a container. The pressure rolls (23), of which there are preferably three, are located on arms (24) and are pivoted or pushed against the rim bead. The pressing action is resilient, for example, by means of springs or pneumatic drive means (25) such that no damage occurs even with lids (1) gripped eccentrically to the rolls (23) or having rim beads with varying shape or diameter. The rolls (23) can also have, in addition to the resilient pressure means, an elastically deformable surface and, for example, contain a layer of foamed rubber beneath a closed surface. In the example shown in the drawings both the universal joint suspension of the suction plate (11) and the resilient pressing action of the rolls (23) contribute to compensate eccentricity. In the indicated position of rest (23a) the rolls (23) have been pivoted away from the path of the lids. In the apparatus there is provided, for example in association with the mounting for the suction plate (11), a sensor device (26) in the form of a probe capable of differentiating inductiwely whether one or more lids (1) are present under the suction plate. Other suitable sensing means may also be used. The sensor device initiates rotation of the suction plate (11) and rolls (23). For the purpose of pressing the rolls into position the travel motion of the suction plate can be slowed down or interrupted for as long as is necessary. Figure 2 shows the rim region of three wedged lids (1). The rim beads (31) differ slightly in shape as a result of being wedged together. Conical roll (33) presses against the outside surface (32) of the top lid held by the suction plate (11) not shown in this Figure. When roll (33) moves around the periphery of the lid or when the lid is rotated against the roll the local deformation at each zone of contact causes the hold to be released and the wedged rim beads fall from or are displaced from the groove (34) formed by the rim bead. Roll (33) is rotated only by contact with the outside bead surface (32) and does not require to be independently driven. Figure 3 shows a different arranGcmcnt- of the rolls, wherein a cylindrical roll (43) presses against the bottom edge of the outside bead surface (32) whilst a second roll (44) bears down on the rim bead 31 and acts as an abutment means. In the apparatus shown in Figure 4 the magazine is inclined at an angle of about 150 to the horizontal and lids are removed obliquely at the same angle. The inclined stack of lids (1) rests against two rolls (51) slowly rotatable in bearings (52,53) by drive means not shown. This in itself provides a measure of loosening in the stack. However, advance of lids by means of plate (3) and placement of the suction plate (11) on the uppermost lid can re-establish wedging between the lids. Thus there are provided in this apparatus pressure rolls (23) which are elastically pressed against the rim bead of the removed lid. Use is also made of three pressure rolls regularly spaced around the periphery of the lid. Because the lids (1) from the inclined magazine cannot be gripped accurately by their centres by suction plate (11) eccentricity must likewise be compensated in this arrangement. At least in that region of the path of travel of the suction plate (11) in which the pressure rolls (23) are pressed against the rim bead of lid (1), the lid (1) and the suction plate (11) must be centerable between the pressure rolls (23) without excessive force on the bead rim being exerted for example by the bottom pressure rolls. The apparatus is therefore provided with a counterweight (not shown) which is effective in at least this position of the suction plate and which can, for example, be located in the housing (54) wherein are further located the drive means for providing the travel motion of the suction plate (11) and rotation when the rolls (23) are pressed against the lid. In this embodiment, simultaneously removed lids also fall back on to the stack. The top end of rolls (51) is arranged such as to continue affording support to the falling lids. The pressure rolls (23) may also be arranged as an extension of rolls (15). The suction plate (11) is withdrawn to the position (llc) as shown. At this point the lid is released by interruption of the vacuum. The lid falls onto the chute (55) and moves to a station (not shown) for placing on containers.

Claims: CLAIMS: 1. A method of separating stacked rounded lids formed with rim beading, particularly lids formed from board, characterised in that each uppermost lid is withdrawn from the stack by gripping of the flat central portion and the rim bead in which a second lid may be wedged is temporarily deformed in a zone or zones extending round the periphery of the lid. 2. An apparatus for carrying out the method of claim 1 comprising a magazine (2) for stacked lids (1) and a suction plate (11) movable in the direction of the axis of the magazine for withdrawing each uppermost lid (1) from the magazine (2), characterised in that during lifting the suction plate (11) is rotatably driven on reaching a certain position and in this position there is arranged laterally of the suction plate (11) at least one pressure roll (23,33,43) pivotable against the rim beads of lifted lids (1) for temporary deformation thereof. 3. An apparatus according to claim 2, characterised in that the suction plate (11) and/or the pressure roll(s) (23,33,43) are resiliently mounted for compensation of eccentric gripping of the lid (1) by the suction plate (11). 4. An apparatus according to either claim 1 or 2, characterised in that the pressure roll (23,33) is pressed against the rim bead such that the line of contact between the roll periphery and the outside surface (32) of the rim bead approximately describes the surface of a conical frustum, 5. An apparatus according to claim 4, characterised in thatt the pressure rolls (23,33) are rotatable about axes parallel to the direction of travel of the suction plate (11) and are conical, the conicity thereof being complementary with the outside surface (32) of the rim bead. 6. An apparatus according to claim 2 or 3, characterised in that at least one pressure roll (47) is downwardly pressable against the rim bead (31) and at least one further pressure roll (43) is laterally pressable against the bottom edge of the outside surface (32). 7. An apparatus according to any one of claims 4 to 6, characterised in that at least three pressure rolls (23,33) laterally pivotable against the outside surface are spaced regularly around the periphery of the lid or suction plate (11). 8. An apparatus according to any one of claims 2 to 7, characterised in that the suction plate (11) in a predetermined position in which the pressure rolls (23,33,43) are pivotable against the periphery of the lid is provided with a drive means (21,22) for at least one complete revolution. 9. An apparatus according to any one of claims 2 to 8, characterised in that the suction plate (11) in the position in which it is most remote from the magazine (2) is laterally pivotable and that there is provided laterally of the path of travel of the suction plate a guide chute onto which the lid falls when vacuum in the suction plate is interrupted. 10. An apparatus according to any of claims 2 to 8, characterised in that the magazine is arranged in an inclined position and comprises two rolls (51) rotatable in the same direction against which the outer surfaces of the rim beads of lids (1) rest and the suction plate (11) is movable in the inclined position, being held by means of a resilient mounting and counterweight in a central position between pressure rolls (23) resiliently pressed against the rim bead of the lid removed by the suction plate (11). 11. An apparatus according to claim 1 substantially as hereinbefore described in the accompanying drawings.

Inventors: MEHLHAUS, ULRICH, SEITZ, WILLI
Applicants: UNILEVER NV, UNILEVER PLC
Application year: 1980
Main classification: B65B43
IPC codes: B65B7