Patent Application
20080251211
1. Technical Field
The present invention concerns an apparatus for producing corrugated cardboard. The improvement offered by the present invention is compactness of whole the plant and easiness of handling the product corrugated cardboard for the subsequent processing steps by reasonable disposition of the components of the apparatus for producing corrugated cardboard.
2. Prior Art
The process for producing corrugated cardboard currently practiced in production of “single wall” product consisting of three layers comprises the following steps:
The corrugated cardboard consisting of five layers called “double wall” is manufactured by stacking and adhering two above-mentioned single facer corrugated cardboards and a front liner material. In this case, in order to satisfy the mechanical properties required to the double wall corrugated cardboard, it is general to use a corrugated cardboard having relatively large corrugation called “A-flute” as the first single facer and the other having relatively small corrugation called “B-flute” as the second single facer.
The corrugated cardboard thus manufactured is, either the single wall or the double wall, continuously withdrawn and usually cut to pieces of suitable length and delivered in the stacked form. Sometimes, however, the product may be further processed by in-line processing such as printing, punching or box-making.
Of the technical problems residing in the corrugated cardboard production the most important is improvement in productivity, i.e., achievement of higher line speed, and this requirement is forever. The single wall product of the A-flute, which is the popular one produced with the highest productivity, can be produced at the line speed of maximum 400 meter per minute. The problem second to this is that concerning the quality of the product, such as no curing or clean surfaces.
The inventor, having made efforts in improvement in technology of corrugated cardboard production for many years, developed some technologies relating to both increase in the line speed and improvement in the product quality. One of the important developments is use of high temperature dry steam prepared by reheating low pressure steam as the heat source of converting water dispersion of starch powder (hereinafter referred to as “raw starch slurry”) applied on the tops of the corrugation (Japanese Patent Publication Sho.59-015066 and Hei.03-065365), and the other is the technology of blowing steam to the core sheet to moisten and heat it prior to application of the raw starch slurry (Japanese Patent Publication Hei.04-074181). He also disclosed another technology of moistening and heating the liner materials (Japanese Patent Publication Hei.06-011521).
In the above-noted technologies the apparatus for moistening is called “moistener”, and the apparatus for heating (and also moistening to some extent), “steamer”. The moistener has function of effecting steam of normal pressure and not so high temperature to the material of corrugated cardboard in the process of manufacturing for the purpose mainly of giving moist to the material so as to facilitate processing the core material to corrugated form, and to prevent excess absorption of water in the applied paste material by the core sheet at rapid rate and in large quantity. On the other hand, the steamer has the main purpose of blowing the heated and somewhat high temperature steam to heat the applied paste material for converting it to gel.
Recent proposal by the inventor is the technology of corrugated cardboard production, in which heating with the conventional heating plates is eliminated. The advance by the new technology is that, in producing decorative corrugated cardboards, surface scratch caused by friction between the board and the heating plates can be avoided in principle. The elimination of the heating plates was realized by preheating the material sheets and full utilization of the moisteners and the steamers (Japanese Patent Disclosure 2006-218841). Another advance is adoption of curing step during which the paste material permeates well and heating of the permeated paste material with superheated steam, instead of heating with the heating plates, to accelerate conversion to gel (Japanese Patent Disclosure 2007-30171).
From the viewpoint of plant formation of the apparatus for producing corrugated cardboard, it is a problem that the components carrying out the above-mentioned corrugated cardboard completion step (step 6) and the subsequent processing-preparation step (step 7) are very long and large. In a typical plant the array of the above-mentioned heating plates is 10 meter long, and the subsequent cooling canvas is at least 10 meter long. Addition of the other components of the plant necessary for the corrugated cardboard production to the above-discussed components results in a whole plant of 90 meters or longer. Based on the practical problem that possible space of building is usually limited, it is desirable that the apparatus for producing corrugated cardboard is more compact.
The problem that the plant is long and large is particularly significant in the technology of producing corrugated cardboard, in which use of the heating, plates is eliminated, proposed by the inventor (the above-mentioned Japanese Patent Disclosure 2006-218841). In the embodiment or utilizing heating with superheated steam instead of the heating plates (the above-mentioned Japanese Patent Disclosure 2007-30171), the period necessary for holding the incomplete corrugated cardboard in the laminated state is somewhat shorter, and therefore, the apparatus for holding the material is not so long and large. However, the whole plant is still long enough that requires some remedy.
The completed corrugated cardboard may be further processed by subsequent in-line processing steps. In general, however, it is easy to practice the steps for corrugated cardboard production and the subsequent steps separately, and therefore, it is often practiced to cut the product into pieces of a certain size and the certain number of thus obtained pieces of the determined size are stacked, and the stacks are delivered to the subsequent steps such as box-making. For this purpose, it will be inconvenient for operation, if the product corrugated cardboards are not placed in the position near the floor level. Thus, it is usual that the steps after lamination of the single facer and the front liner material are carried out on the floor level of the plant. Typical distribution of the apparatus components is as shown in
The object of the present invention is to solve the above discussed problem that whole the plant will be long and large and to provide a compact and easy-to-operate apparatus for producing corrugated cardboard, which begins with preparation of the single facer corrugated cardboard to go to lamination of it with a front liner material, and to eliminate the step of carry down the product corrugated cardboard.
The apparatus for producing corrugated cardboard according to the present invention comprises, as shown in whole in
The following explains the apparatus for producing corrugated cardboard according to the invention in detail. The respective components of the apparatus comprise the elements described below:
The component (I) for processing the core material to the corrugated core, continuously laminating the corrugated core and a back liner material with a paste to form a single facer corrugated card board comprises, in a preferred embodiment, as shown in
Then, the component (II) for continuously laminating the single facer corrugated cardboard and the front liner material with paste to form an incomplete corrugated cardboard to form an incomplete corrugated cardboard comprises, in a preferred embodiment, as also shown in
The component (III) for obtaining completed corrugated cardboard by heating the incomplete corrugated cardboard to complete adhesion with the paste comprises, in a preferred embodiment, as shown in
The component (IV) for cutting and stacking to deliver the product to subsequent processing steps comprises, as also shown in
Usually, the component is equipped with a roller conveyer to deliver the stacked corrugated cardboard pieces to the next processing steps.
Alternatively, in such cases as mass-production of boxes of the same size, an in-line punching device for punching the produced double facer corrugated cardboard to determined shapes and sizes may be installed instead of the cutter and the stacker. The component (IV) of the present invention may include such an embodiment.
The superheated steam-blowing nozzles (P) disposed in the heating zone (Y) and the accessories thereof are disclosed in detail in the above-mentioned Japanese Patent Disclosure 2007-30171. They are, however, shown in
As shown in the graph of
If the internal core (corrugated material) has high water-absorbing property, only the water in the raw starch slurry applied is absorbed by the paper, and as the result, water content of the paste material becomes insufficient and gelling or paste formation is not appropriately realized. Thus, desired adhesive power cannot be obtained. (adhesion under insufficient paste formation) On the other hand, if the core is of low water-absorbing property, then permeation of the raw starch slurry into the core is difficult, and the result of this is one-side gelling and adhesion occurs under the condition that the paste resides only on the surface. (adhesion of surface only)
The latter phenomenon tend to occur in the case where a strongly sized paper called “reinforced internal core” is chosen as the internal core of the AF with the intention to strengthen the double wall corrugated cardboard. Such a trouble is often experienced in cases where the corrugated cardboard just after a couple of hours since production, which apparently seems completely adhered, is handled with hands. The product may easily decompose into sheets with terrible noise. Only when the permeation of the raw starch slurry is appropriate and it is properly gelled, desirable adhesion (permeation adhesion) may be achieved.
It will be understood from the graph of
Because the apparatus for producing corrugated cardboard according to the present invention eliminates use of heating plates, this apparatus can be conveniently used for production of so-called decorative corrugated cardboard. In that case, one or more of apparatus for carrying out the decorative printing or processing on the front liner material, such as that selected from the group of flexo-printer, gravure-printer, and embossing press (none of them are shown in the drawings) as desired. These apparatus may be usually installed on the first floor near the means for supplying the front liner material.
