Let's talk about the materials used for the body of refrigerated trucks, such as stainless steel, aluminum alloy, fiberglass, and so on. The choice of material depends on the needs of the merchant.

The glass steel plate has the advantages of heat insulation and water impermeability. Some insulation box composite plates are not heavy, not easy to deform, and the plate structure is compact. The thermal insulation performance of such refrigerated vehicles is excellent. The glass steel plate panel on the surface of the composite plate has no such water permeability, but its rigid polyurethane foam has large closed holes and strong water resistance.

1. Allow the composite board to fully cure

The composite board forming process is a step by step crosslinking reaction of resin molecular functional groups under the action of curing and promoting agents at room temperature. Before the reaction, the raw material resin molecules are linear macromolecules with many functional groups - unsaturated bonds - on the molecules.

During the reaction process, under the action of styrene crosslinking agent, they crosslink with each other to form bulky macromolecules, transforming the entire structure into a bulky structure, thus forming thermosetting plastics. The subsequent curing process takes a longer time at room temperature. If the curing period does not meet the requirements during the production process, that is, the degree of solidification is not enough, the molecules will exhibit partial thermoplasticity internally.

The characteristic of thermoplasticity is that it melts or softens when heated, resulting in plastic deformation. Make its size larger than the original size, that is, the panel size is larger than the mold size.

Due to the limitations of the mold, if the panel is larger than the mold and cannot be stretched, it is prone to wrinkling. As the temperature and time increase, the curing degree of thermosetting resin molecules increases, and the molecules undergo cross-linking reactions to form a body structure. The panel and box board are cured and formed, and the composite board is not easy to stretch. This is the fundamental reason for wrinkling of refrigerated compartment boards.

Therefore, in the quality control process, the composite board must undergo a one week post curing treatment after solidification to ensure that its curing degree meets the national requirements and reduce quality problems.

2. Reduce molding temperature and extend molding time

Refrigerated compartment panel composite board is a reinforced plastic with good performance and thermal deformation temperature. If we blindly increase the heat deformation temperature, it will increase costs and is not very meaningful. Based on this, during the molding of the box board, the molding temperature was reduced by 5-6 ℃ on the basis of the original molding temperature. In order to fully mold it, the molding time can be extended by 10 minutes.

3. Avoid displacement of embedded parts

The embedded parts in the box board are essential structural components for connecting and fastening the box board. Require neither to affect structural strength nor wrinkling. Regarding this, improvements have been made in the size and structure of the embedded parts, with the size of the embedded parts slightly smaller than the original design by 2-3mm.

To compensate for the defects caused by this, reinforced materials can be used as a cushion layer to surround the embedded parts and fill the space formed by the small size of the embedded parts. After curing, it can be integrated with the box board. This not only solves the problem of displacement caused by embedded parts, but also enhances the structural strength.

4. Ensure the accuracy of material cutting

Equipment maintenance personnel must perform regular maintenance and overhaul of composite panel cutting equipment, and regularly calibrate measuring instruments. The precision of cutting equipment should be high and meet the accuracy requirements. Key measuring instruments that do not meet the requirements shall be repaired or replaced.

Refrigerated truck manufacturers must comply with the ISO9002 quality system operation requirements for human factors causing cutting errors, strengthen employee training, and obtain a job certificate before being allowed to work. Quality inspectors must strengthen inspections.

5. Composite board leveling

First, lay out the composite board and use a pre made fixture to clamp and press both ends of the composite board tightly. After the refrigerated compartment boards are arranged, remove the fixture before pressing with the press.