Abstract:
The economical packaging device for large-sized thin glass panes stacked horizontally on each other for long-distance transport includes a first shock-absorbing packaging case for a stack of raw glass panes that are cut to predetermined dimensions and stacked horizontally oriented with interleaving layers between adjacent panes, which satisfies the mechanical requirements for external freight traffic, and a second shock-absorbing packaging case for a stack of subsequently processed substrate glass panes that are stacked horizontally oriented with interleaving layers between adjacent panes, which satisfies the mechanical requirements for internal transport within a glass processing or working operation. To further reduce breakage risk the second shock-absorbing packaging case has outer dimensions selected so as to be receivable in a shock-absorbing manner in the first shock-absorbing packaging case for additional packing during external transport of the substrate glass panes.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     1. The Field of the Invention  
         [0002]     The present invention relates to a packaging device for horizontally stacked large-sized thin glass panes, especially display or window glass panes.  
         [0003]     2. Related Art  
         [0004]     In the case of the present invention the term “large-sized thin glass panes” means glass panes with a thickness on the order of 1 mm, especially display glass panes with a thickness of less than 1 mm, and a size with dimensions of 1500 mm×2500 mm and also dimensions of 1100 mm×1300 mm. The packaging device according to the invention is mainly suitable for thin glass panes with smaller sizes, but provides an economical solution to the packaging problem.  
         [0005]     During manufacture of comparatively thick large-sized flat glass panes up to a size of 1500×1000×8 mm, especially of improved flat glass panes for the home construction area, flat glass is cut to form raw glass panes of the required size and subsequently processed to form so-called substrate glass panes, whose edges are processed and which are polished. The flat glass panes are assembled in containers of different types. The raw glass panes are typically removed manually from a conveyor system, optically checked and subsequently from 5 to 10 panes are stacked in a container for transport to subsequent processing steps.  
         [0006]     For protection of the sensitive surfaces from damage, for example due to scratching, and dirt a great variety of materials—so-called interleaving materials—are placed between the flat glass panes in different ways. The flat glass pane stacks are subsequently manually wrapped with additional material—preferably paper—as needed. These packets are subsequently placed in available disposable or reusable containers. This happens horizontally or vertically arbitrarily according to choice. The packets of flat glass panes secured by means of a strap system are subsequently transport-ready. Motion of the flat glass panes in the packet is prevented in part alternatively to straps, also with additional filling material. The packets are manually opened by the customer for further processing and after that the glass stack is unpacked piecewise—partially automatically.  
         [0007]     Different bonded and un-bonded materials can be currently used for the interleaving layers.  
         [0008]     Un-bonded materials are provided either directly on the glass or on support materials, which then function jointly as separating means. The disadvantages of these un-bonded interleaving layer materials are that they are not simply and reliably manually removable—also they are not free of visible residue—or this process must involve further effort and difficulties, for example it must include a washing process. These un-bonded materials are, for example, PMMA balls and powder or even natural materials, such as cork. Furthermore they wander increasingly due to the spaces formed during production, where they have negative effects during subsequent processing.  
         [0009]     The bonded materials may be categorized as either in strip form or flat form.  
         [0010]     Interleaving layer strips are often provided with adhesive layers, which either electrostatically or adhesively adhere to the glass. The disadvantage consists in the chemical reactions occurring between the glass and the adhesive or adherent layer. Electrostatic adherence on one side of a layer of material can only be attained by an expensive bonding material. Adherence on both sides is not desired, since the later separation from the glass is difficult. Rigid strips are also known, which are not fixed to the glass and are held in position within the stack purely in a form-fitting manner, for example by flanging the lateral edge, as described in U.S. Pat. No. 3,837,636. However it is very difficult to automate this latter type of interleaving layer structure. A minimum material thickness must be selected in order to obtain the required stiffness to prevent warping during or after application, which considerably reduces the packing density of the stack.  
         [0011]     Special papers, which can be adjusted or fit to the dimensions of the glass panes and are placed loosely on them, are used especially as flat bonded materials. The effort involved in finishing or dressing these materials is a disadvantage. Also considerable volumes and masses of residual material, which must be thrown out, arise disadvantageously during unpacking. In addition the risk of harmful inclusions in the paper increases with the maximum covered glass surface area. Chemical reactions by undefined ingredients in the paper caused, e.g. by humidity, are not prevented.  
         [0012]     Additional possibilities result from adherent plastic foils, which are laminated over the entire surface. Products are obtained, which are residue free, however not automatically removable. These products are provided with additional desirable properties, such as UV protection or extreme scratch resistance. It is not necessary to separate the flat glass when these products are used, which would result in additional costs.  
         [0013]     In addition, there are mixed materials, as described in GB 1 366 264, which are sprayed e.g. in liquid/plastic form to form strips and subsequently hardened or bonded to one or both sides by subsequent local heating. Also U.S. Pat. No. 5,607,753 discloses combinations, such as e.g. powdered strips acting as separating-interleaving layers.  
         [0014]     However, as a group, these known materials leave traces or residues behind on the glass surface, which are difficult to remove.  
         [0015]     DE 101 40 003 A1 discloses a method for large-sized, but comparatively thick, glass panes (of the order of about 10 mm), which avoids the above-described disadvantages.  
         [0016]     Generally, in spite of the above-described known methods, the problem of packaging of thin glass (glass thickness of the order of 1 mm), especially of display glass of larger sizes, for marketing has still not been satisfactorily solved, in so far as no standard solution has been advanced. Even for external packing, i.e. for packing suitable for long-distance transport, no structure has been found that satisfies all requirements. Interleaving materials for intercalated layers between the glass panes are known and are scalable for larger sizes. The classical method of transporting flat glass, in which the flat glass is transported in a vertical orientation in wood frames or racks or gently tilted in metal frames or racks, which are adjusted to the larger sizes, finds application here. Raw glass panes in the polished state, i.e. substrate glass panes, in the smaller sizes are packed in a packing box so that they do not touch each other using spacers according to the above-described state of the art, in order to avoid destructive scratching of the surface.  
         [0017]     However the insertion of spacers is no longer possible with increasing size of the thin glass panes, since the bending of the panes would be large enough so that the necessary spacing corresponding to the maximum bending would lead to inefficient storage space utilization. If great bending occurs during transportation according to current practice due to braking events and bumping, a high probably of destruction of the thin glass panes would exist.  
         [0018]     There is thus a need to scale raw glass packaging for larger sizes, i.e. to adjust the current packaging practice to increasingly large sizes. As described above, generally it is not possible to use the current packaging methods for substrate glass of larger sizes. The development of new packaging solutions is thus necessary.  
         [0019]     Currently the general transport standard in the flat glass industry is the vertical or gently inclined transport of glass panes. High stability of the glass pane for standing on a cut edge provides the basis for this transport method. Application of this method to display glass with substantially smaller thickness makes strong clamping of the glass pane with the rear wall of the packaging device necessary, in order to prevent fanning out of the thin panes at their base and to guarantee that the thin glass panes stand upright. The vertical or gently inclined orientation must be produced by a suitable additional attachment device. Additional effort must then be performed, in order to place the thin glass panes completely parallel to each other. With increasing numbers of panes in the arrangement an attachment to the rear wall, which guarantees that the thin glass panes stand vertically on the base plate becomes increasingly difficult to guarantee. A higher force must be applied with increasing numbers of pieces, which leads to an increased breakage risk. The breakage risk thus increases enormously, when the thin glass panes are not perpendicular to the cut edge.  
         [0020]     These problems have stimulated further research to find new solutions for packaging of, among others, large-sized display glass.  
         [0021]     In the current era of globalization typically raw glass panes are only manufactured in one country and the subsequent processing to form substrate glass panes, which is very labor intensive, typically occurs in another low-wage country, from where it is sent to the consumer, i.e. the glass processing operation, e.g. a display manufacturer. Thus the packaging for the raw glass panes must meet the requirements for freight traffic, typically by means of trucks or sea freight, including the associated loading devices, for example a forklift truck.  
       SUMMARY OF THE INVENTION  
       [0022]     It is an object of the present invention to provide a packaging device for stacked, large-sized thin glass panes of the above-described type, so that they can be transported in large arrangements with large numbers of thin large-sized glass panes through the entire logistics chain from the raw glass pane manufacturer to the subsequent glass working plant for producing substrate glass panes and from there to the glass processing plant in a dirt-free and scratch-free manner, while avoiding the above-described breakage risk.  
         [0023]     According to the invention the packaging device for large-sized thin glass panes stacked horizontally on each other comprises  
         [0024]     a first shock-absorbing packaging case for a stack of raw glass panes that are cut to predetermined dimensions and stacked horizontally with interleaving layers, which has a mechanical stability according to mechanical requirements for external freight traffic; and  
         [0025]     a second shock-absorbing packaging case for a stack of subsequently process substrate glass panes that are stacked horizontally with interleaving layers, which has a mechanical stability according to mechanical requirements for internal transport within a glass processing or working operation;  
         [0026]     wherein the second shock-absorbing packaging case has outer dimensions selected so as to be receivable in an shock-absorbing manner in the first shock-absorbing packaging case for external transport of the stack of substrate glass panes.  
         [0027]     The packaging device according to the invention successfully transports large stacks of large-sized thin glass panes with a minimum breakage risk in an economical dirt-free and scratch-free manner over the entire logistical chain from the raw glass panes to the substrate glass panes processed from the raw glass panes and then to the glass processing operation. The system is economical because the first freight-traffic-stable packaging case for the raw glass panes can be also be used again for external shipping of the second packing case containing substrate glass panes. 
     
    
     BRIEF DESCRIPTION OF THE DRAWING  
       [0028]     The objects, features and advantages of the invention will now be illustrated in more detail with the aid of the following description of the preferred embodiments, with reference to the accompanying figures in which:  
         [0029]      FIGS. 1A and 1B  are respective schematic top and side views of a first packaging case for a stack of horizontally oriented, large-sized thin glass panes, in the form of raw glass panes;  
         [0030]      FIGS. 2A and 2B  are respective schematic top and side views of a second packaging case for a stack of horizontally oriented large-sized thin glass panes, in the form of substrate glass panes;  
         [0031]      FIGS. 3A and 3B  are respective schematic top and side views of a packaging device according to the invention for shipping substrate glass panes, formed from a combination of the first packaging case according to  FIG. 1  and the second packaging case according to  FIG. 2 ; and  
         [0032]      FIG. 4  is an exploded perspective view of the packaging device according to  FIG. 3 . 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0033]      FIGS. 1A  to  4  show the packaging device according to the invention for large-sized plate-shaped, rectangular thin glass panes, especially display glass panes or plates, comprising a combination of a raw-glass-pane or first packaging case and a substrate-glass-pane or second packaging case.  
         [0034]     In order to make stable economical transport of the glass panes even in large numbers possible, horizontal packing is used in principle, which allows a great number of glass panes, e.g.  200 , stacked one on the other to be transported without spacers. A “glass block” from a plurality of glass panes stacked without spacers has a great stability. Also horizontal packaging permits high density during storage, because the packaged arrangements or stacks themselves can be stacked over each other.  
         [0035]     In the packaging device according to the invention the glass panes thus rest with their large surfaces in contact with each other, only separated by thin interleaving layers, stacked over each other. Preferably a paper interleaving layer is used with raw glass panes and a protective foil is used with the substrate glass panes.  
         [0036]      FIGS. 1A and 1B  show one embodiment of a transport packaging case according to the invention for large-sized rectangular thin raw glass panes  1 , which have dimensions of 1920 mm×2245 mm.  
         [0037]     The transport packaging case has a rectangular frame  2  made of wood or metal, which permits horizontal transport of a large number of glass panes, e.g. up to  200 , i.e. a suitably large arrangement. This frame  2  is constructed in a conventional way like a grate or lattice, either from joined together wood pieces or from metal sections welded with each other ( FIG. 4 ). It has a smooth removable planar base  2   a  for stable support of the glass panes to prevent breakage, and has a lateral post  3  with a foot plate  3   a  at each corner. The lateral post height is determined by the maximum stack height of the raw glass plates. The foot plate  3   a  assists the stacking of the frames in storage and transport. Guiding openings  3   b  act to assist insertion of the fork fingers of a forklift stacker. The first or transport packaging case has a flexible rubber mat  4  acting as bottom support in order to absorb shocks or damp impacts during transport.  
         [0038]     Stable plastic side panels  5 , constructed preferably as hollow chamber panels and mounted in a framework  5   a  made of wood or metal with vertical crosspieces  5   b,  form the side cover or lateral closure of the packaging device. They are preferably removable to simplify the loading process and have eyes  5   c  on both ends for this purpose, with which they are hung on the lateral posts  3 . Shock-absorbing laterally spaced pads  6  comprising foam plastic are provided inside of the frame in order to protect the edges of the glass panes laterally from contact with the frame or the side panels  5 . For protection from damage the corners  1   a  of the glass stack remain free from contact with any element of the packaging. An interior attachment is provided, which rests on the glass block and is clamped in a conventional manner with the side walls  5  of the frame, in order to hold the stacked glass block fixed during partial loading for transport. An outer cover  7  is further provided for extended protection of the arrangement ( FIG. 4 ).  
         [0039]     The loading of the first or transport packaging case with raw glass panes typically occurs in accordance with  FIGS. 1A  and B.  
         [0040]     The raw glass panes cut from a continuous glass sheet are provided with a full-surface interleaving layer made of paper, are removed from the conveyor belt, preferably by means of a suction lifter, and are stacked separately from each other in the frame  2  with the covering side panels  5  removed. This process is typically completely automated. When the maximum load is reached, the side panels  5  are manually hung on the four lateral posts  3 . Subsequently the loaded packaging device or arrangement is moved by means of a forklift stacker to a storage place or a shipping place for external transport. Typically it is loaded into a container.  
         [0041]      FIGS. 2A and 2B  show an embodiment of a second packaging case for stacked substrate glass panes  8 , which correspond to raw glass panes  1  as shown in  FIGS. 1A and 1B  with about 3 cm of their edges removed during edge working of the raw glass panes. The substrate glass panes  8  have a reduced size of namely 1860 mm×2185 mm. The edges of the raw glass panes are ground and the glass surface polished in addition to removal of glass from the edges during preparation of the substrate glass panes in a glass working operation.  
         [0042]     The second packaging device has a stable tank-shaped or pan-shaped plastic box  9 , preferably formed from hollow chamber panels, with sufficient stability for automatic internal transport. The dimensions of the plastic box, which are given for the selected embodiment shown in  FIG. 2B , are such that the rectangular cross-sectioned plastic box for shipping of the substrate glass panes can be inserted in the stable rectangular frame  2  of the raw glass pane or first packaging device according to  FIGS. 1A and 1B , as can be seen in further detail with the aid of  FIGS. 3A and 3B .  
         [0043]     The thickness of the outer wall of the plastic box is thus at maximum identical with the edge of the glass panes removed during the subsequent glass working steps used to make the substrate glass panes plus the insulating material thickness of the raw glass packaging case. Furthermore the weight of the box may not exceed the weight of the material of each stack removed during edge processing, so that the stability of the edge frame  2  is not endangered. The plastic box  9  can be sufficiently well cleaned and immersed for dust-free clean room processing.  
         [0044]     As in the case of raw glass packing according to  FIGS. 1A and 1B  shock-absorbing or shock-absorbing side pieces  10  (pads) of insulating material, preferably of clean-room-compatible (particle-free) material, are provided between the edges of the stack of substrate glass panes  8  and the inner wall of the plastic box  9 . The stack corners remain free of insulating material, i.e. for protection of the corner from damage the corners remain free of contact with any material. In the insulating-material-free edge zone the base or bottom  9   a  of the box  9  is visible in  FIG. 2B .  
         [0045]     Protective foils acting as interleaving layers are found between the substrate glass panes. That means that each substrate glass pane  8  is covered on both sides with a foil. The entire stack of the substrate glass panes is enveloped or covered with a foil, which guarantees dust-free packaging. This foil is placed in the plastic box  9  prior to the stacking of the glass pane.  
         [0046]     According to  FIG. 2A  the plastic box  9  is closed with a cover  9   b,  in order to guarantee, in so far as possible, a dust-free transport of the stack of glass panes.  
         [0047]     The stack of the substrate glass panes  8  in the plastic box  9  occurs in a similar manner as in the case of the raw glass panes. The internal transport of the plastic box occurs preferably automatically by means of a roller conveyor, including the placing of the plastic box in the raw glass packaging device, preferably with the side panels  5  and base plate removed.  
         [0048]      FIGS. 3A and 3B  together with the exploded perspective view of  FIG. 4  show the packaging device for shipping the stack of substrate glass panes  8 , comprising a combination of the raw-glass-pane package frame  2  according to  FIGS. 1A and 1B  with the substrate pane plastic box  9  according to  FIGS. 2A and 2B , which is received in the package frame  2 , which serves as the outer box.  
         [0049]     The stability of the inner box is designed for transport in the manufacturing between packing away of the substrate glass panes and their final packaging in the outer box. The transport stability for truck transport, sea freight and air freight is guaranteed by the substantially more stable outer box.  
         [0050]     This concept has cost advantages, especially on account of the further use of the raw-glass-pane packaging case, which is supplied anyway during the glass processing operation, as an outer packing for the substrate glass panes.  
         [0051]     The horizontal packaging lowers the storage costs because of the about 50% higher storage density provided by horizontal stacking.  
         [0052]     The disclosure in German Patent Application DE 10 2004 061 021.5-27 of Dec. 18, 2004 is incorporated here by reference. This German Patent Application describes the invention described hereinabove and claimed in the claims appended hereinbelow and provides the basis for a claim of priority for the instant invention under 35 U.S.C. 119.  
         [0053]     While the invention has been illustrated and described as embodied in a packaging device for stacked large-sized thin glass panes, it is not intended to be limited to the details shown, since various modifications and changes may be made without departing in any way from the spirit of the present invention.  
         [0054]     Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can, by applying current knowledge, readily adapt it for various applications without omitting features that, from the standpoint of prior art, fairly constitute essential characteristics of the generic or specific aspects of this invention.