Although the structure of folding cartons varies widely and has not yet reached the national standard, they are all suppressed by the creases of printed cartons or cardboards, and then passed to the user for folding and packaging by the user. The structural design of the folding carton is flat, and we customarily refer to the folding carton design as a box. It has been found that the box is formed by a number of closed planes in accordance with certain rules, and each closed plane basically corresponds to a functional surface of the carton behind the box, so that each separate face of the carton can be divided into A box piece part, in the folding carton structure CAD system studied by the author, the essence of the carton structure design is that the different box piece parts are assembled into a box piece by the flattening technology.
I. The basic principle of legality
The basic idea of ​​the splicing technique is to compose complex objects with simple regular-shaped geometry. The splicing algorithm differs greatly depending on the entity representation and data structure chosen for each system. From the topological point of view, the merging operation classifies the points of the participating objects and finds the set of points that constitute the result of the operation.
Cartridges are flat graphics, which are simpler than 3D solid modeling. The box piece parts are subjected to operations such as axisymmetric transformation, centric symmetry transformation, mirroring, rotation, and shifting, and are positioned and modified by copying, copying, deleting, enlarging, reducing, etc. The box piece parts are connected into a box through a common edge. sheet.
II. Box piece parts
1. Composition and division of box parts
The box piece part is a basic unit that constitutes the box piece and is an entity of the basic idea of ​​"constituting a box piece by a box piece part." A box piece part is a closed plane pattern enclosed by a strip edge, and the lines constituting the box piece part can be divided into border lines and non-boundary lines, and the border lines are further divided into connectable edges and non-connectable edges. All boundary lines make up the closed outer boundary of the cassette parts. Only the connectable sides can be shared by the two cassette parts to form the connection of the two cassette parts. When the cassette parts are not connected to the cassette, Peripheral is a single solid line, representing the contour cutting line. After the cassette is inserted, the common edge of the two cassette parts corresponds to the indentation line in the actual cassette.
The box of the folding carton can be regarded as being composed of a box cover, a box body, and a box bottom, and the folding carton is further subdivided, and each independent face of the carton can be divided into a box piece part, and the box piece is split into The basic principle of the box-sheet part is that each independent plane after being boxed is split into a box-piece part, and for some two or more surfaces that are closely related in structure, they can also be combined into one box-piece. Considering the parts, the study found that the main change structure of the folding carton is the lid and the bottom of the box. There is no change in the box. Therefore, the lid, box, and box bottom can be seen as separate parts of the box, that is, the general folding. The carton can be regarded as being formed by different box lids and box bottoms assembled by the box body, as shown in Fig. 1 (a) main swinging wing and inserting tongue, due to the latching structure between the two parts, in terms of structural dimensions There are strict restrictions, so it is divided into a box piece part, (b) Because the window is opened, the two sides of the window are treated as the same box part. According to this rule, the folding carton box sheet can be divided into the hierarchical structure as shown in FIG. 2 , and the function surface of the carton is separated, that is, the carton is divided into various parts. Make the unpacked parts into a parts library so that they can be called directly during the cartridge design process. When creating a cassette library, care should be taken that the cassette part must be parametric, ie the geometric parameters that make up the cassette part must be adjusted automatically as needed.
2. Cartridge piece assembly
When the box piece is assembled into the box piece, only one side of a piece of the box piece is determined to be connected to one side of other box piece parts, and the shape of the box piece cannot be uniquely determined, and the box piece part must be transformed (eg: axis Symmetrical transformations, centrosymmetric transformations, rotations, shifts, etc.), determining their relative positions, etc. As long as the first part is determined, after each subsequent part is selected, it is determined sequentially whether or not it needs to be converted and the distance between the end of the edge of the part that is to be connected to the box piece and the starting point of the side to which it is connected, and finally the unique composition can be determined. Box slice illustration. Take Figure 3 as an example to briefly introduce the process of assembling the parts of the cassette, (a) call the adhesive edge in the part library, (b) perform axisymmetric transformation of the adhesive edge as required, (c) from the library of cassette parts One part of the box is called out. (d) The parts of the box are moved together with the glued edge. (e) The stitching is completed. The common edge is changed from a single solid line to a single dotted line to indicate the inner indentation line.
The flattening technology is applied to the carton structural CAD system. The user can not only store the assembled cassettes in the cassette library as required, but also can directly call the cassettes in the cassette library to modify them.
The application of spelling in the folding carton structure CAD system is of far-reaching significance. It can not only accurately realize the structural design of the folding carton and ensure the product design quality, but also provides the conditions for the next carton design. , Reduced its dependence on designers, reduced labor intensity, opened up a new era of computer technology in carton structural design, greatly shortened the design cycle, saved costs, and enhanced the market competitiveness of enterprises and designers. .
(Author/Luo Guanglin Zhang Xiaohui Yu Jiang)
Ningbo Ruichang Commodity Packaging Co.,Ltd , http://www.nbrcpackaging.com