Common vacuum forming machine

Vacuum forming process of carbon fiber composite

by:Mengxing     2021-04-09

In the production process of carbon fiber composite materials, the vacuum liposuction method can produce large and simple products at low manufacturing costs, and obtain better quality. Combining the traditional vacuum bag molding method and the resin transfer molding method, using two pre-drilled hoses to guide the resin into the vacuum bag to quickly impregnate the fiber, which can greatly shorten the filling time and effectively reduce manufacturing cost. Use resin vacuum diffusion molding to make polymer composite laminates. With the pressure difference generated by vacuuming, the resin is quickly poured into the vacuum bag to impregnate the fiber.

Vacuum forming process

   Introduction to Vacuum Liposuction

The traditional vacuum bag molding process is to pre-impregnate the fiber with resin, and after drying and gelling, control the resin to reach the stage of drying and not sticking to the hands. This stage is called stage B (, and then use this prepreg. The laminated sheet is placed in a vacuum bag, heated and pressurized to harden into a product. The process of fiber prepreg resin is the main factor causing the high manufacturing cost. In view of this, in order to effectively reduce the cost and maintain the vacuum The advantage of the excellent quality of the bag method is that the filling process of the resin injection molding method is combined with the traditional vacuum bag method to replace the original prepreg fiber step, and a new concept of resin vacuum injection is proposed to manufacture large flat members. The method currently used is to make the resin into a film, place it under the fiber, place it in a vacuum bag, heat it to melt the resin and impregnate the fiber. But this method requires the resin to be made into a film, which does not melt at room temperature, and can be used as a material Therefore, it is limited. Another effective device is to lay a layer of special resin distribution medium on the top and bottom of the fiber stack, and the resin can quickly and freely flow through the entire resin distribution medium when filling the mold, and then vacuumize it. The bag is squeezed downwards so that the fibers are impregnated with resin.

The resin vacuum injection manufacturing process is to pre-place the fiber laminate in a vacuum bag, then vacuum, and guide it by two pre-drilled hoses. The pressure difference generated by the vacuum is used to quickly make The resin is poured into the vacuum bag to impregnate the fiber, and then the inlet and outlet are closed to keep the vacuum bag in vacuum, allowing atmospheric pressure to produce a squeezing effect on the impregnated fiber laminate, and finally solidify and form at room temperature or high temperature.

  Vacuum introduction method

   1. Resin configuration and degassing: The resin and hardener are separately prepared in a weight ratio of 100:35 and placed in a conical flask. Then use a degassing device to vacuum to remove the gas originally in the reagent. Because the viscosity of the resin is too high, turn on the heater of the electromagnetic heating stirrer (the temperature is maintained at about 80°C), and turn it off after heating for about 30-45 minutes. But it should be noted that the hardener should not be heated.

2. Pre-place the laminate in the vacuum bag: arrange the fiber laminates in order, place them in the vacuum bag in order, then place the resin tube and the vacuum resin outlet on the laminate, and finally put silica gel and The vacuum tape seals around the vacuum bag. Pay attention to pressing the vacuum tape and the vacuum bag tightly.

  3. Preheating: Place the mold and vacuum bag on the platform of the hot press, and apply a preheating temperature of 70°C. At this time, the resin conduit and the vacuum resin outlet are matched according to the vacuum injection system.

  4. Filling the mold: Pour the degassed resin and hardener into the beaker carefully, stir evenly, put it into the injection pressure tank, and wait for the mold to be filled. At this time, it should be noted that the pressure tank cover does not need to be closed. The mold filling is to use the vacuum to make the pressure difference between the bag and the outside, and the compressed resin enters the vacuum bag through the tube. Before filling the mold, open the vacuum pump to draw out the air in the bag before filling the mold, open the resin inlet, and start filling the mold. After the resin enters the duct, start to calculate the filling time and observe the flow field. Wait until the resin is completely wetted. After the laminate is finished, let the resin continue to flow and let the air bubbles flow out at the outlet, close the vacuum resin outlet, but do not close the resin inlet, keep it for a period of time, let the resin continue to enter, and finally wait until the resin is stable and no longer enters , Close the resin inlet to complete the mold filling.

  5. Curing and demoulding: Place the laminated finished product filled with moulds at room temperature for curing. After the finished product is cured, open the vacuum bag and take out the finished product, which is complete.
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