NO314048B1 - Detachable gripping and holding device designed for lifting large plates and method for releasing the holding device from large plate mounting position - Google Patents

Abstract

A releasable grip-and-hold device for panelling boards (28), pivotally mounted on the extreme end of a pivoted boom (18) of liftable/lowerable board-handling apparatus. Said device comprises a board-supporting frame (26) with hooks (32) for securely holding opposite board edges until the moment of release from the device in the mounting position of the board. The hooks (32) are formed on respective end sections (34) of said frame (26) and are connected to the frame (26) in a pivoted, spring-loaded manner. A wire (62) leads from a fixed point (60) on the supporting frame (26) at the pivot point (30) thereof, to a constructional element on the board-handling apparatus. When the boomwork (18) is pivoted, the wire (62) provides for the supporting frame (26) to be rotated 180 DEG from a stack of panelling boards (28) lying horizontally, and so that the supporting frame (26) with the panelling board (28) lying on top is sloping slightly in the longitudinal direction. This sloping position of the panelling board (28) resting on top of the supporting frame (26) via small pivoted supporting means (44), then bringing it into a displacing motion, so that it first pivots the supporting means (44) and then exerts a push force on the hooks (34), which pivot resiliently away in order to start the successive release of the panelling board (28) from its grip-and-hold device.

Description

RELEASEABLE GRIP AND HOLD DEVICE DESIGNED FOR LIFTING

OF LARGE PLATES AND PROCEDURE FOR RELEASE OF THE HOLDING DEVICE FROM THE MOUNTING POSITION OF THE LARGE PLATE

This invention relates to a releasable gripping and holding device designed to grip large plates, for example plasterboard, individually and hold the single plate during subsequent swinging/lifting, and comprising a plate support frame which is pivotally connected to a substantially horizontal axis to the end of a pivotable boom on a preferably drivable plate handling device, where mutually parallel, releasable gripping and holding devices comprising hooks, hook-like organs or the like are arranged along two opposite transverse side edges of the support frame, such as at least at one of the aforementioned transverse edges are each designed/arranged on end parts, which at their opposite end are pivotably mounted to the other support frame via a pivot shaft, thereby holding the plate firmly during its swing/lifting and placement in the mounting position, where it is released from the undersize frame's gripping and holding devices .

The invention also relates to a method for releasing a gripping and holding device of the type in question from a large plate that has been placed in the mounting position, where the support frame carries small, pivotable support members against which the underside of the plate rests when the support frame has been swung around said essentially horizontal axis from a position which corresponds to the stacking position of the large plate to a position which at least approximately corresponds to the mounting position of the large plate, and where all hooks are pivotable and spring-loaded.

The gripping and holding device comprises, in a known manner, a support and retention frame with peripherally positioned holding means which positionally fix the rectangular plate on the frame during the swinging and lifting, moving and handling from the plate stack (the plates can be stacked standing in a steeply inclined position or lying on top of each other) to the plate's mounting position, where the plate must be released from the frame as soon as it is brought into precisely set mounting position and fixed - at least temporarily - for later, complementary retrofitting.

It is known from FR 2538437, US 3467261 and Fl 885745 apparatus for handling large plates. None of the aforementioned publications show devices that grip, lift, place in mounting position and release the plates from the device in one operation without the plates having to be handled manually.

According to the present invention, it is intended to provide a gripping and holding device for plates, where, on the one hand, a secure retention of such plates is achieved individually during lifting, swinging movements and handling in general, and where, on the other hand, a reliable release of gripping and the holding device as soon as a plate has been brought into its precisely set mounting position.

In the case of a plate gripping and holding device of the kind specified in the introductory part of patent claim 1, the above-mentioned purpose is realized by the device being designed and arranged so that it exhibits the features that appear in the characterizing part of patent claim 1.

Such a gripping and holding device comprises, in a known manner, a support frame for the plate.

In the case of two or more straight, mutually parallel frame parts of the support frame, a hook-shaped gripping/holding device is arranged at both free ends, which hooks in the position of use are directed towards each other with the hook tips, the end parts of the parallel frame parts each having a hook - at least at one transverse side of the support frame is pivotably arranged about an axis parallel to the pivot axis of the support frame and is held in an upswing, effective gripping and holding position by a spring device that allows downward swinging to release a plate from the gripping and holding device at least at one of two opposite, retained plate side edges, the plate thereby being in reality detached from the gripping and holding device which only needs to be moved in a direction away from the rear hooks, in order to cancel their grip on the nearby, transverse plate edge.

The pivotable mounting of the outer end part with hook of two or more frame parts at at least one transverse side of the support frame and the said end part's spring-loaded tilting inclination towards the active position where the parallel end parts appropriately assume a slightly upwardly inclined position from the pivot point to the adjacent hook, in combination with hooks at both transverse sides of the frame, enables gripping and holding of one plate from a stack, swinging of the plate and handling it in the held position until it is brought into precisely set mounting position and secured.

Preferably, the end portions of the frame parts of the undersize frame which carry the hooks are all pivotable and resiliently returnable in operative position, which facilitates the gripping of a plate from a stack and also the release of the plate in a fixed mounting position, but this pivotability at both transverse sides of the support frame is not critical to the implementation of the invention's main function.

The pivotable, spring-actuated hook-bearing end parts which are located at one transverse side of the support frame can advantageously be provided with a control and deflection means for the respective pivotable end part. In an advantageous embodiment, this body can take the form of a curved leaf spring-like element attached to the pivotable, hook-equipped frame dividing end portion which, with the respective hook in an upward position (for example in the mounting position of the plate) curves downwards (convex in the upward direction). When its free end hits a wall when a plate is brought into mounting position, the control element is deflected in the direction of movement and it pulls the hook-bearing end part with it, which consequently swings springily downwards and lifts its grip on the plate edge. The plate is then in reality freed from the plate handling device's gripping and holding device, because the latter can be moved straight forward by said boom until the plate is stopped by a wall or the like at its front edge, after which the boom can be moved in the opposite direction.

The support frame can be provided with, in the upwardly directed position of the gripper and holding hooks, also upright, small support members, each of which can have an upwardly convex support surface against which the plate's underside rests against during the various plate handling operations. These small support members can pivot/tilt to a limited extent when the plate is being placed in precisely set mounting position and their curved bearing surface is gentle on the plate and facilitates the release of the plate from the gripping device in the p1a te mounting position.

By proceeding as stated in the characterizing part of patent claim 13, based on a device as stated in patent claims 1 and 9, a simple and reliable release of a large plate in the mounting position from the gripping and holding device according to the invention can be achieved.

At a plate thickness of approx. 13 millimeters can each be notched, with the dimension parallel to the plate edge surface being approx. 15 millimetres, and the chin tip part can have a free-ended finger-like extension of approx. 1.5 millimeters and which forms an (obtuse) angle with the surface of the primary chin.

The primary hook surface starts approximately perpendicularly from a rectilinear end part of a frame part which is part of the support frame, and where the hook is formed on the outer free end of the frame part, which has an upper and a thus parallel, lower edge surface. The outer end of said lower edge surface and the upper end of the chin surface are connected to each other via an arc-shaped transitional edge surface, which is convexly curved in the direction away from the pivot point of said frame part's chin-bearing end portion. The small finger-like extension hook can run at least approximately tangentially to said convexly curved transition edge surface. This so-called secondary extension hook must have a very insignificant extent in relation to the primary hook's effective extent, which is dependent on the thickness of the actual plate dimension.

As mentioned, each pivotable hook-bearing end part of the support frame is assigned a spring which, among other things, functions as a return spring that allows the hook-bearing end part to swing down when a ceiling plate is released from the gripping and holding device according to the invention when the plate is brought into the mounting position. Respective springs pull the respective pivotable end part in the use position slightly upwards to a slightly sloping position where the chin is slightly higher than the end part's pivot point. Such a position favors the gripping and holding ability of the composite hook (primary hook with secondary hook) just opposite the adjacent plate edge.

An example of a preferred embodiment is explained in more detail below with reference to the accompanying drawings, where: Fig. 1 in side view shows a drivable plate lifting and handling device which, at the outer, free end of an articulated, pivoting boom, carries a gripping and holding device designed in accordance with the invention; Fig. 2 shows the situation in fig. 1 on a significantly larger scale; Fig. 3 shows - compared to fig. 1 - apparatus, device and plate in positions where the gripping and holding device with the plate is swung 180° about the horizontal axis of the boom end, and where the handling device's boom has lifted/swinged the plate into a horizontal position at a relatively short distance from the ceiling in a room; Fig. 4 shows largely the same situation as in fig. 3, but with the plate in a position somewhat closer to the ceiling, and where the plate-releasing (slight) inclined position has caused oscillation of the small, pivotable support members and swing away of the pivotable, spring-loaded hooks as a result of the displacement of the large plate towards the lowest point of the support frame, whereby the upper transverse edge of the plate has had the opportunity to be pulled out by the hooks placed on the left, after which the plate is in reality free; Fig. 5 shows the curved steering and movement-deflecting spring element attached to a hook against a wall just below the ceiling; Fig. 6 corresponds to fig. 5, but shows the pivoting of the end portions; Fig. 7 shows an enlarged partial view of the one in fig. 6 showed situation; Fig. 8 is a side view, partly in vertical section, where the plate in question is to be mounted in the extension of an already mounted ceiling plate; and Fig. 9 shows an immediately following phase in the one in Fig. 8 showed situation;

Fig. 10 shows the support frame alone seen from above.

Reference is first made to fig. 1-4, where in fig. 1 shows a plate lifting and handling device which comprises a carriage 10 with running wheels 12, an upright boom work column 14 mounted on the carriage 10, which at the top carries a telescopically extendable/shortenable boom 18 pivotable about a horizontal pivot axis 16. Between a point 20 on the boom 18, which is significantly closer to its pivot axis 16 than its outer end, and a lower point 22 on the boom column 14, a piston cylinder 24 is fitted, which initiates the boom 18's pivoting movements about the pivot axis 16.

Between the boom's outer, free end and a support frame 26 for the large single plate 28 which is to be lifted, swung and moved with the aid of the handling device, a link 30 centrally located in relation to the support frame 26 with a horizontal axis ensures the pivotability of the support frame 26 in relation to the boom 18. The support frame 26 is equipped with a gripping and holding device according to the invention, which includes gripping and holding hooks 32 directed towards each other. most figures, are considered one of the support frame 26's two long sides, because they extend parallel to the boom 18.

According to fig. 1 and especially fig. 2, each hook 32 is formed at the end of an end portion 34 or an end part of a longitudinal frame part, the support frame being thought of in a known manner to be built up of interconnected, longitudinally and transversely running frame parts, which are located in largely the same plane.

Each end part 34 on at least one transverse edge is rotatably connected at its end opposite the hook 32 to the associated frame part of the support frame about a horizontal shaft 36. The hooks 32 located to the right can be rigidly connected to their associated frame part, but that provides a more flexible support frame, especially when gripping and retaining a plate, when all gripping and holding hooks 32 are pivotably arranged in the manner shown.

A return spring 38 is arranged for each end part 34 with hook 32. This return spring in the form of a tension spring allows end part 34 with hook 32 to be swung down with the hook 32 only when the plate is to be released from the gripping and holding device.

Each chin tip can be extended with a short finger 40 which can have an orientation, see fig. 7, where its longitudinal direction runs roughly tangentially to an arc-shaped end surface 32a on the hook-bearing end part 34 of the lower support frame 26, which is pivotably suspended at the end of the boom 18 about said horizontal axis 30.

The chin-bearing end parts 34 at one (left) transverse side edge of the support frame 26 are each provided with a control and movement deflection element 42 for the pivotable, chin-bearing end part 34, in order to initiate the pivoting movement of the end part 34 when the free, furthest-protruding end/end portion of the - movement deflecting control element comes into contact with, for example, a vertical wall surface 50, fig. 5 - 7, and cooperates with this during the continued linear advancement of the support frame 26 with the plate 28.

Of important components, the support frame 26 also carries four or more (two are visible in the side views according to the drawing figures) small pivotable support members 44, whose individual pivot point 46 is parallel to the support frame 26 pivot point 30.

According to, for example, fig. 5, each of the small pivoting/tilting support members 44 has an upwardly convexly curved support surface 44a for a plate 28.

A ceiling and an immediately adjacent vertical wall are denoted by 48 and 50 respectively, while the floor in the same room is denoted by 52, fig. 3.

The control and movement deflection element 42 can advantageously have a rounded, for example hook-shaped end 42a, which helps to promote the element 42's deflection ability. The rounding at the end of the control and movement deflection element thereby ensures that the element, when it hits a wall 50 or other vertical surface/edge, is set in an end-part guiding, downward-swinging displacement movement along said surface/edge.

In fig. 9, adjacent side edge surfaces 28b and 28c of the plates 28 and 28a are brought together and form a joint 54.

The element 42 is resilient and flexible. The chin tip extending finger 40 can have the same properties, particularly when the chin-bearing end part 34 swings down when mounting the carried/handled plate 28 to abut against the free transverse side edge surface 28b of an already mounted plate 28a, fig. 8, where the curved chin end surface 32a which ends in the chin tip in combination with the springy, flexible chin tip extending finger 40 in controlling cooperation with the plate edge surface 28b initiates a sufficient downward swing of the chin bearing end part 34 about the pivot axis 36, to release the handled plate 28 leading edge 28c from hook 32 with securing finger 40.

When installing a plate 28 in the ceiling 48, the underframe 26's gripping and holding device picks up a plate 28 from a stack of horizontal plates lying on top of each other, fig. 1 and 2. In this position, the support frame 26 is turned 180° about the axis 30 in relation to the plate-supporting position according to fig. 3-9.

When the support frame 26 with the hooks 32 facing downwards, fig. 2, is lowered onto the uppermost plate 28 in the stack, the hook-carrying end parts 34 of the support frame 26 swing springily upwards, whereby the hooks 32 are moved somewhat outwards in the longitudinal direction of the frame 26 and then downwards, after which they will grab hold of opposite side edges of the plate 28 when the support frame 26 is raised by means of the piston cylinder driven boom 18.

To swing the support frame 26 from the one in fig. 1 shown, large plate gripping position at the stack of plates 28 lying horizontally on top of each other, where the support frame 26 is located above the plate 28 that is taken from the stack, it is, for example fig. 1, arranged a very elongated, flexible rope-like element, for example in the form of a wire. This rope-like cable element and its effect in combination with the boom's 18 swinging movements are described in more detail later. For now, it should only be mentioned that the length of the wire and attachment points are so coordinated in relation to the swinging movements of the boom structure 18 that the support frame 26 with one large plate 28 is swung approximately 180°.

The plate thickness can be, for example, 13 millimetres, and it is then natural to choose a chin height of approx. 15 millimeters and a chin tip-extending finger length of 1.5 millimeters. With these hook dimensions in relation to an assumed plate thickness, a secure grip on a plate 28 is achieved.

Held by such a gripping and holding device, the plate 28 is swung somewhat over 180° about the axis 30 to the slightly downward-sloping position which can be seen in particular from fig. 4.

Fig. 4 shows the plate 28 in a position where it is mainly in the mounting position, i.e. in the position where the plate 28 is desired to be released from the gripping and holding device, i.e. from the hooks 34, as at both transverse edges of the support frame 26 in fig. . 4 are pivotable and spring-loaded.

The longitudinally slightly downward sloping position (from left to right) in the direction of the plate handling apparatus 10,14 is created after the support frame with the plate was first positioned in a horizontal position, where the plate 28 rested on the small, pivotable support members 44 which then assumed positions directed perpendicularly on the plane of the support frame/plate.

The relatively insignificant tilting of frame 26 with overlying plate 28 and intermediate support members 44 creates a displacement movement component in plate 28 in its plane. With fixed hooks 34, the plate 28 would be retained and said movement component counteracted. In the case of pivotable spring-loaded hooks 34 at both transverse edges of the support frame 26, two different release movements will now occur which complement each other, and each of which is a binding prerequisite for the other to be able to be carried out.

Said movement component, which acts in the plane of the large plate 28, initiates an extraction of the left edge part of the large plate 28 from the hook parts 32, 40, which initial extraction movement when supported together by the left transverse edge 2 6 will simultaneously produce a pressure effect in the plane of the plate 28, aimed at the hooks 34 at the support frame's right transverse edge. The pivoting, springy hooks 34 at the right transverse edge will thereby swing down with their outer, free hook portion 32,40. This swinging down of the right hooks allows the plate 28 to shift diagonally downwards to the right, so that the left edge part of the plate 28 is completely pulled out by the adjacent hooks 34, whereby the plate 28 is in reality completely freed from the gripping and holding device according to the invention.

In fig. 4-7 illustrates how the control and movement deflection element 42,42a causes a downward swing of the respective hook-bearing, spring-loaded end part 34 while utilizing the control and movement deflection element 42,42a's stop and sliding displacement possibility downwards along the side wall 50, fig. 6 and 7, in which sliding displacement the curved chin end surface 32a also participates.

When a plate 28 together with the support frame 26 has been rotated 180°, the plate 28 is in a supported position where it rests on at least four limited swivel/tilt small support members 44 with upwardly convexly curved bearing surfaces 44a and individual pivot axes 46 on the support frame 26.

Such support members 44, each of which has a horizontal pivot axis, represent support elements from which the plates 28 can easily be released in the mounting position after the plate has been released from the pivotable hook-bearing end parts. By considering fig. 6 in connection with fig. 5, it is possible to ascertain the pivotability of a support member 44 by placing a plate 28 in the mounting position in contact with the ceiling surface 48 and with the leading edge surface in contact with the adjacent wall surface 50.

As mentioned at the outset, it is sufficient that the hooks 32 at one transverse edge of the support frame are pivotable. The chin-bearing end parts 34 at the left transverse side edge of the support frame 26 can be individually pivotable downwards about a horizontal axis 36 and assigned returning, rebounding tension springs 38, and each one of them preferably equipped with a steering and movement-deflecting spring element 42 with a rounded outer end and preferably with a hook tip-extending, flexible finger 40. The right hook-bearing end portions 34 of the support frame 26 may be rigidly connected to the rest of the frame 26, because a supported, supported plate 28 which is released from the gripping and holding device's left hook devices 32,34, 36,38, is practically released from the gripping device already. By placing such a supported plate with free (left) leading edge 28c, see fig. 8, in contact with a wall 50 at the top of the ceiling 48 or against the transverse edge 28b of an already mounted plate 28a, only a rectilinear displacement movement of the support frame 26 is required to cancel the grip on the plate 28. However, it is most advantageous that all the hook-bearing end parts 34 are individually pivotable.

Each of the individual tension springs 38 ends is attached to an attachment ear 56 on the support frame 26 and an attachment ear 58 on its pivotable, hook-bearing end part 34.

In what follows, a wire 62 will be mentioned in conclusion which has a first fixed attachment point 60 on the support frame 26 and a second fixed attachment point 66 on the plate handling apparatus 10,14 column-like construction part 14, at the top of which the boom 18 is pivotably arranged.

The horizontal pivot axis 30 of the support frame 26 is created by a pin attached to the boom end which is rotatably supported between two bearing lugs 68 attached to the support frame 26 and which preferably has the form of two parallel disc segments which form a cord/track disc in which the wire 62 is controlled, from the first fixed attachment point 60 on the support frame 26 between the bearing tubes 68, until it has entered the cavity in the square tube which forms the boom structure 18. For the guidance of the wire 62, guide discs (not shown) can be arranged, and in the area of said second fixed attachment point 66 for the wire 62, the latter is assigned a tension spring or gas spring 64 which is to prevent the wire 62 from being worn off at the wrong angle of rotation for the frame 26.

The length of the wire 62 and the choice of the attachment points are based on construction and/or experience. During the swinging movements of the boom about the axis 16 by means of the hydraulic/pneumatic piston-cylinder 24, the support frame 26 with the plate 28 (from the plate stack in Fig. 1) will be forcibly swung, first to a horizontal intermediate position under the ceiling 48 and then to a slightly downward-sloping release position, fig. 4. The release of the plate 28 from the support frame 26 gripping and holding device is described above.

Claims (13)

1. Releasable gripping and holding device designed to grip large plates (28, 28a) individually and retain the individual plate during subsequent lifting/swinging, and comprising a plate support frame (26) pivotally connected about a substantially horizontal axis (30) to the end of a pivotable boom (18) on a preferably drivable plate handling device (10,12,14,16,20,22,24), where mutually parallel, releasable gripping and holding devices comprising hooks (32), hook-like organs or the like, which at least at one of the mentioned transverse edges each is designed/arranged on end parts (34), which at its opposite end is pivotably mounted to the other support frame (26 ) via a swing shaft (36), thereby holding the plate (28) firmly during its swing/lifting and placement in the mounting position, where it is released from the support frame's (26) gripping and holding devices, kara characterized in that the releasable gripping and holding device is provided with coercively acting transmission means (62,64) which, from a first gripping position for the gripping and holding device in the case of horizontally/vertically stacked plates (28), when the boom structure (18) swings, leads support the support frame (26) through a swing angle about the aforementioned essentially horizontal axis (30), which swing causes the support frame (26) to lie below the plate (28). 2. Releasable gripping and holding device according to claim 1, characterized in that said transmission means comprise at least one very long, rope-like, tensile element, for example in the form of a steel wire rope (62), which is attached at one end to the support frame (26) in a fixed point (60) at the essentially horizontal axis (30) of this frame (26), which steel wire rope (62) extends along and preferably inside the boom structure (18) in order, with its other end, to be fixed in another fixed point (66) on the upright structural part (14) of the plate handling apparatus which carries the boom (18), preferably under the intermediate connection of a tension spring (64) or similar elastically yielding extendable/shortenable element with damping function. 3. Releasable gripping and holding device according to claim 1, characterized in that the swiveling hooks (32) have means (32a, 42, 42a) which, upon impact against a stationary surface, for example on a wall (50), initiate downward swinging of the respective hook (32) pivotable, spring-loaded end part (34) of the support frame (26), for the release of the plate (28, 28a) from the hooks (32). 4. Releasable gripping and holding device according to claim 1, characterized in that each swiveling hook (32) has an arc-shaped or curved outer end edge surface (32a) which starts from the hook surface and extends from the tip of the hook to the straight outer end edge of the swiveling end part (34). 5. Releasable gripping and holding device according to claim 1, characterized in that at least the swiveling hooks (32) are provided with a finger (40) emanating from the tip of the hook which at least has an approximately tangential course in relation to the hook's (32) curved end edge surface (32a). 6. Releasable gripping and holding device according to claim 4 or 5, characterized in that the swiveling hooks (32) on one or both transverse edges of the support frame (26) are provided with a steering and direction of movement deflecting, preferably flexible, elongated element (42) which extends forward in front of the chin (32) in the longitudinal direction and is attached to the chin-bearing end part (34) and has a curvature in the supporting and carrying position of the support frame (26) which follows an upwardly convex curved course, and which is designed to is slidably displaced along a surface/edge (50) which it may encounter during the support frame's (26) essentially horizontal displacement movements, and by its sliding displacement to pull with it and swing down the hook-bearing, pivotable end part (34). 7. Releasable gripping and holding device according to claim 6, characterized in that the guiding and movement direction deflecting element (42) for the hook-bearing, pivotable end part (34) of the support frame (26) has an outer, for example hook-like end rounding (42a). 8. Releasable gripping and holding device according to any one of the preceding claims, characterized in that each hook-bearing, pivotable end part (34) of the support frame (26) is assigned a return tension spring (38) which has an end attachment ear (58) on said pivotable end part (34) and an end attachment ear (56) on the support frame (26). 9. Releasable gripping and holding device according to any one of the preceding claims, characterized in that the support frame (26) carries small, pivotable support members (44) against which the underside of the plate (28) rests when the support frame (26) has been pivoted about said essentially horizontal axis (30) from a position corresponding to the stacking position of the plate (28) to a position at least approximately corresponding to the mounting position of the plate (28). 10. Releasable gripping and holding device according to claim 9, characterized in that each pivotable support member (44) is provided with a convexly curved support and support surface (44a) outwards from the pivot point (46) towards a part of which curved surface (44a) of the plate (28) flat bottom surface rests 11. Releasable gripping and holding device according to any one of the preceding claims 2-10, characterized in that the essentially horizontal pivot axis (30) between the support frame (26) and the end of the boom (18) is created by means of a transverse bolt attached to the boom end, which is stored between a pair of bearing lugs (68). 12. Releasable gripping and holding device according to any of the preceding, characterized in that in the lifting position with plates (28) from the horizontal plane, the pivot shaft (36) which connects the pivotable end part (34) to the support frame (26), is placed at a higher level than the chin (32) which constitutes the extreme point of the releasable gripping and holding device 13. Method for releasing a gripping and holding device as designed in claim 9 from a large plate (28) which has been brought into mounting position, and where all end parts (34) are pivotable and spring-loaded, characterized in that the support frame (26) with the overlying large plate (28) in or in the immediate vicinity of the mounting position of the plate (28) and with the plate (28) resting on top of the upright, pivotable support members (44), is placed in a slightly inclined position, so that the plate (28 ) is set in a displacement movement which causes swinging of the support members (44) in the same direction as the support frame (26) slopes downwards, which swing of the support members (44) with the overlying large plate (28) causes the hitherto gripped and fixed plate edge portion to be pulled out by the pivotable, spring-actuated end parts (34) at one transverse edge of the support frame (26), as it set the large plate (28) in displacement motion via its opposite p flat edge will exert a pushing force against the pivotable, spring-actuated end parts (34) at the other, opposite transverse edge and swings these end parts (34) springily away from their active position, so that the aforementioned plate edge extraction from the hooks (32) can find place.