There are actually many materials for the body of refrigerated trucks, such as stainless steel, aluminum alloy, glass fiber panel, etc. The choice of material depends on the needs of the plant.
FRP, it has the advantages of heat insulation and impermeability. Some insulation box composite panels are not heavy, not easy to deform, and the sheet structure is tight. The insulation performance of such refrigerated trucks is excellent, while fiber glass panel on the suface of the sandwich panels has no such water permeability, but its rigid polyurethane foam has large closed cells and strong water resistance.
Process production of refrigerated truck box:
1. Let the composite board fully solidify
The composite board(FRP sandwich panel) molding process is at room temperature, under the action of curing agent and accelerator, the resin molecular functional group is cross-linked and formed step by step. Before the reaction, the raw material resin molecule is a linear macromolecule with more functional groups on the molecule-no Saturation bond.
During the reaction process, under the action of the styrene cross-linking agent, they cross-link each other to form a body-shaped macromolecule, so that the entire structure becomes a body-shaped structure, that is, a thermosetting plastic is formed. The subsequent curing process takes a long time at room temperature. If the curing period does not meet the requirements during the production process, that is, the curing degree is not enough, and the inside of the molecule is partially thermoplastic.
Thermoplasticity is characterized by being melted or softened by heat and plastically deformed. Make the size larger than the original size, that is, the panel size is larger than the mold size.
Due to the limitations of the mold, the panel larger than the mold cannot be stretched, and it is easy to wrinkle. As the temperature rises and the time increases, the degree of post-curing of the thermosetting resin molecules increases, and the molecules undergo cross-linking reactions to form a body structure. The board is solidified and the composite board is not easy to stretch, which is the root cause of the wrinkle of the refrigerated compartment board.
Based on this, in the quality control process, the composite board must undergo a one-week post-curing treatment after curing to ensure that its curing degree meets the requirements of the national regulations and reduce quality problems.
2. Lower the molding temperature and extend the molding time
The refrigerated compartment board composite board is a kind of reinforced plastic. The resin is produced according to the formula of the Dutch DSM company, and its performance and heat distortion temperature are better. If you blindly increase the heat distortion temperature, it will increase the cost, which is of little significance. According to this, during the molding of the box panel, the original molding temperature is reduced by 5 to 6°C. In order to make it fully molded, the molding time can be extended by 10 minutes.
3. Avoid displacement of embedded parts
The embedded parts in the compartment plate are the structural parts for the connection of the compartment plate and are indispensable. The requirement neither affects the structural strength nor wrinkles. In this regard, improvements have been made in the size and structure of the embedded parts, that is, the size of the embedded parts is slightly smaller than the original design by 2 to 3 mm.
In order to make up for the defects caused by this, reinforcement materials can be used as a cushion to enclose the embedded parts and fill the space formed by the small embedded parts. After solidification, it will be integrated with the compartment board. This not only solves the problem caused by the displacement of the embedded parts, but also enhances the structural strength.
4. Ensure the accuracy of cutting
Equipment maintenance personnel must carry out regular maintenance and overhaul of composite board cutting equipment, and regular inspection and calibration of measuring instruments. The cutting equipment must have high accuracy and meet the accuracy requirements. If the key meter does not meet the requirements, it must be repaired or replaced.
For the human factors of blanking errors, it is necessary to strengthen the training of employees in accordance with the requirements of the ISO9002 quality system. Quality inspectors must strengthen inspections.
5. Pave the composite sandwich board
The composite sandwich board is spread out first, and the two ends of the composite sandwich board are clamped and compressed with a pre-made clamp. After the refrigerated compartment board is arranged, the clamp is removed before the press is pressed.
In this way, since the foam board is pressed on the composite board, the composite board on the bottom surface is no longer warped. The above composite board, because its area is larger than the size of the box board, can be fixed on the mold with tape. After this treatment, observe the formed box board, the outer edge of the composite board is flush with the outer edge of the box board, and the size of the surrounding edges is basically uniform.