It is convenient for beginners of FRP to understand the forming process of vacuum bag. This article illustrates the simple process of vacuum resin guide for carbon fiber parts of automobile, hoping to be helpful to you.
In fact, there is not much difference between the requirements of vacuum pumping and hand pasting for most of the FRP shell formed by vacuum bag. However, the flange of the vacuum mold is relatively larger (such as 15cm), which is convenient for the butyl tape to bond and seal the vacuum bag.
Vacuum operation steps
Step 1: clean the surface of FRP mold and apply mold release agent; first, stick the sealing tape to the flange of the mold, considering that: 1. The flange of the mold is large enough, and subsequent operation is not hindered. 2. Prevent scattered carbon fiber debris, which may cause air leakage when sealing at flange edge.
Paste the sealing tape step 2: cutting the carbon fiber cloth
Carbon fiber cloth shall not be cut too small, and the burrs to be cut in the later period shall be fully considered. You can also cut the carbon fiber cloth in advance. If it's not easy to calculate, you can cut a piece first, try to lay it, and then cut it in order according to the size.
The third step of cutting carbon fiber cloth: laying carbon fiber cloth
For the laying of multi-layer carbon fiber cloth, you can use set spray glue, which is easy to bond and lay to the surface of the mold. Don't spray too much, because it is easy to have potential risks of poor combination.
Try not to pull the texture of the first layer of carbon fiber cloth askew when laying carbon fiber. You know the principle of selling a piece of leather!
Step 4: lay the release cloth
The demoulding cloth will not stick to the product. After the parts are solidified and formed, it can be easily torn off, and a woven pattern mark similar to the cloth pattern is formed on the back of the product.
Step 5: lay the diversion net
The main function of the guide net is to promote the resin flow and disperse the epoxy resin in the whole product layer quickly and effectively.
Step 6: lay the spiral pipe, place the rubber inlet and outlet
The spiral pipe of resin injection seat is the conveying and dispersing channel of resin. Because it is a spiral open type, when the resin flows in one direction, it will quickly disperse to the flow guide net and the whole carbon fiber cloth layer.
Arrange resin guide pipe step 7: lay and stick vacuum bag film
Because of the simple structure and long gelation time of epoxy resin, it is not necessary to worry about the additional diversion of resin. Find a symmetrical position at will, and arrange a rubber inlet and a rubber outlet respectively. The vacuum bag should be cut larger and sealed carefully to avoid bridging and piercing the vacuum bag. Vacuum! Ensuring air tightness is paramount.
Step 8: connect vacuum pump and resin collector with vacuum tube
When PVC hose is used to connect the vacuum equipment and resin collector, it can be cut into an inclined angle, so that the hose can be pushed into the vacuum nozzle in the vacuum bag, and then sealed with butyl tape.
The resin collector shall pay attention to these positions, and it is easy to cause slight air leakage due to the lack of pressure on the sealing tape.
Vacuum pump step 9: vacuum leakage test
Fold the rubber inlet pipe in half and test the overall vacuum tightness to determine whether it meets the requirements of resin vacuum pumping.
PVC vacuum pipe carefully look for the leakage point, correct and reseal. Once the vacuum degree meets the requirements of the parts, subsequent operations can be carried out.
Step 10 of vacuum test: weigh and mix epoxy resin and curing agent correctly
Epoxy resin configuration note that the epoxy resin and curing agent must be accurately measured and evenly mixed, or the product may soften or the resin is always in the sticky state.
11 steps of vacuum epoxy resin: Vacuum introduction of epoxy resin
Due to the relatively simple structure of the part, the flow diversion speed of the vacuum epoxy resin will be very fast, and the visual inspection of this small part is generally 15-20 minutes enough to complete the flow diversion.
12 steps of introducing vacuum resin: wait for the epoxy resin to cure and remove auxiliary materials
After the completion of the epoxy resin diversion, the rubber inlet and air outlet can be cut off, waiting for the epoxy resin to cure completely; generally, the curing can be completed after heating 60-80 ℃ for 3 hours. It takes more than 24 hours to cure at room temperature. After curing, the vacuum auxiliary materials shall be stripped after demoulding.
13 steps of carbon fiber part demoulding: cutting and polishing the parts
After cutting the carbon fiber parts, it is recommended to polish them with sandpaper by water grinding; the reason why dry grinding is not recommended is that the grinding dust is pressed into the surface pinhole, because it will be cleaned up very well.
Step 14: repair the pinhole on the surface of carbon fiber parts
It is difficult to completely eliminate the pinholes on the surface of epoxy resin parts, because this is the reason that carbon fiber cloth has weaving staggered points, twill cloth is relatively better than plain cloth.
For the surface pinhole treatment of automobile carbon fiber parts, you can use epoxy resin glue to fill or spray 2K varnish for sealing. Varnish anti UV effect will be better, but the strength is not as high as epoxy resin, which is more suitable for you, I will weigh it according to the actual situation.
This is the case of carbon fiber. A simple car carbon fiber case is basically vacuumized. Of course, not all the vacuum parts are the same operation, because the structure of the parts is different from the actual requirements, and the specific operation is slightly different, but the basic routines are almost the same.
Source: FRP experience