The unique properties and shortcomings of pulp molding products

2. Structure design of paper molded products Pulp molded products as a new material used in buffer packaging time is short. At present, its structural design is still in the experience design stage, the design of pulp mold products should be based on the appearance size of the packaged product, the size of the outer container to be reasonably determined.

Pulp molded products in each side must consider its damping effect, so the convex to achieve the purpose of buffering, so that it on each surface of the section line are broken lines, to improve the strength of the paper die. The strength of the paper die is inversely proportional to its buffering performance. The more convex ribs are added, the greater the strength is, but at the same time its buffering performance decreases.

Pulp mold products have a smooth surface (with the surface of the molding mold) and a rough surface, the shape and size of the smooth surface to be packaged products are consistent with the surface; The rough surface should be able to implement good support and fixation in the outer packaging of the product (such as cartons, etc.).

Pulp molding products are formed by vacuum adsorption process, and the absolute thickness and thickness difference of each part are limited by the forming conditions. Under normal circumstances, the absolute thickness of the pulp mold products is 2 ~ 5mm, which requires us to ensure the overall dynamic buffer performance by setting the cavity on the appropriate part, and set a certain number of reinforcement to ensure its overall strength, although the thickness of each part of the pulp mold products can be controlled by adjusting the opening rate of the corresponding part of the molding mold. But too large thickness difference in the molding and drying process is difficult to ensure the quality of pulp molding products. When forming, the dryness of the wet paper mold blank is about 10%, and the slurry still has a certain fluidity, which is easy to produce fiber flow in the vertical direction, causing local fiber flocculation phenomenon, affecting the molding quality, especially for the pulp mold products with larger vertical size, this situation is more serious. Therefore, it is necessary to design a certain slope in the vertical direction of the pulp mold product, which is also conducive to the demudding of the wet paper mold blank. Under normal circumstances, its slope design is 2o ~ 5o. At the surface corner of the pulp molding product, it is necessary to avoid right Angle or acute Angle contact, otherwise, it is easy to produce stress concentration phenomenon here, and the reasonable treatment method is to use rounded corner transition.

In the structural design of pulp molding products, the edge structure should be properly considered, and the edge structure of paper molding products has a boundless structure, a flanging structure and a double edge structure. The boundless structure is suitable for disposable tableware and some industrial internal packaging products with light weight and low strength requirements; Flanging structure and double edge structure are mostly suitable for industrial inner packaging products, which can improve the overall strength of paper mold products, buffer performance and beautify the appearance of products.

The mold design of the pulp molding products is the key to the entire production process. First of all, it must meet the structural requirements of the pulp molded products and the above molding process conditions (that is, the impact of pulp molding on the molding mold, dehydration and drying process), and then it must meet the requirements of mold design and manufacturing.

The molding process of paper molding products mainly includes vacuum adsorption molding method and grouting molding method. Vacuum adsorption molding method is the most commonly used molding method in the production of paper pulp molding products. In this process, the final paper pulp molding products can become qualified products after many times entering and leaving the mold. The molds used in pulp molding include adsorption molding molds, finishing molds and die-cutting molds.

1. Adsorption molding mold The structure of adsorption molding mold is composed of punch, concave die, mesh die, mold base, mold back cavity and gas chamber, etc. The mesh mold is the main body of the mold. Because the mesh mold is woven from a diameter of 0.15mm wire mesh (metal or plastic), the mesh number is generally between 40 and 65 mesh. It cannot be independent of the molding mold and must be attached to the surface of the mold to form. The mold back cavity is a mold that maintains a certain thickness with the mold working face and is completely synchronized with the shape of the mold working face. The cavity formed between the back part and the mold seat, that is, the convex and concave die, is a shell with a certain wall thickness. The working face of the die and the back cavity are connected by a uniform small hole. The die is mounted on the formwork of the forming machine by the die holder. The other side of the template is equipped with an air chamber, which is communicated with the back chamber, and the wall of the air chamber is provided with two channels for compressed air or vacuum extraction.