With the rapid development of the transportation network, the demand for passenger buses is increasing. The requirements for the safety and comfort of passenger cars are also increasing. The beauty and luxury of interior parts have also become one of the important symbols of high-end luxury passenger shuttles. Mold for vacuum forming buses should be designed carefully.
According to the material of plastic vacuum forming, it can be divided into two types: plastic sheet forming and soft skin plastic sheet forming. The material is mainly ABS sheet. There is a small number of parts produced with plexiglass (PMMA) sheet.
The inner panels on the left and right sides of the passenger bus’s cab, the top inner panel, the rear inner panel, as well as some electrical box covers and other covers are made of ABS sheets. Now there is also a trend of replacing ordinary ABS sheets with composite ABS sheets. Composite ABS sheet is to add a layer of foamed polypropylene or polyvinyl chloride material on the sheet, and roll them together to form a sheet with skin texture or feel like leather. The sound cover of the instrument panel that requires transparency, and the ventilation grille outside the body that requires anti-aging, are generally made of plexiglass.
Now take vacuum forming the inner panel of a passenger car as an example to briefly describe the process of thermoforming. The size of the part is 1200*1000*250mm, and the size of the ABS sheet used should be 1400*1200*4mm.
First of all, it is necessary to confirm the color and texture of the board, it is very important for decoration. The first thing passengers feel about when they get on the car, is the environment inside.
Then check if the board is taken out from the freshly opened packaging bag, if not, the board needs to be dried in the drying room. If the sheet is wet, bubbles will form on the surface of the sheet during heating. The appearance quality will deteriorate. And in severe cases, the sheet will be cracked during the forming process.
At the same time, the mold will be installed on the blister machine, the position and frame to be adjusted, and the rising process and time of the mold will be preset. The top of the mold cannot exceed the working platform of the blister machine.
Heat the mold to about 60℃. The plastic sheet is placed on the automatic feeding device, and the machine sends the board to the table of the blister machine. The pressing frame presses the board from top to bottom. Then the heating mechanism is moved to the top of the workbench to heat the plate.
Generally heated to about 120 ℃, and time is 2 to 3 minutes. If it is advanced equipment, you can also set the regional temperature of the heater, and increase the heating temperature appropriately where the stretching is large. After heating, the heating mechanism is removed, and the mold starts to move upwards at the same time. Then vacuum forming starts.
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