1. Repair FRP defects and damages during processing or use and maintenance. Such as pores, delamination, degumming, inclusions, poor glue, rich glue, incomplete resin curing, fiber bending, wrong paving sequence, fiber voids generated during hand lay-up and curing molding; scratches generated during mechanical processing and assembly The structural abnormalities caused by scratches, bumps, collisions, degumming, fiber breaks, non-straight holes, over tightening, etc., which do not meet the design requirements, should be repaired.
Repairable defects are the outstanding features of FRP and fiberglass cementitious composite materials. These repairs are almost all done by hand. The connection of FRP, whether it is mechanical or glued, is to a large extent repairing and repairing FRP. Enhanced measures.
The repair of FRP can be divided into surface damage repair and structural damage repair. The repair of surface damage is more than the repair of structural damage. The repair process is the same as that of FRP molds and other products. The repair process is shown in Figure 11-19.
Use a saw blade or a grinding wheel to carefully scrape the surface wrinkles, and shovel a V-shaped gap at the break of the gel coat; blow off the dust with compressed air, clear with acetone; fill it carefully with a brush dipped in gel coat resin, etc., and make it as flat as possible or slightly higher On the original surface; coat the surface and cover the plastic film; after the resin is completely cured, use sandpaper to sand in the order of fineness.
For minor defects or damages, non-reinforced plates can be used to repair, and for larger damages, reinforced plates are used to repair, but in fact a mixed form is adopted. For large cracks and fractures, a combination of resin injection and reinforcement should be used. First clean the cracks with acetone, remove the protruding burrs, air dry, inject the resin glue, and patch the FRP. For the fractured part, the glass fiber reinforced plastic reinforcement plate should also be riveted and reinforced with bolts.
Putty and cement are indispensable materials in the molding and maintenance of FRP. Putty, also known as cement, is also a kind of cement, and one of the main components of cement is filler. The main purpose of putty is to make filling materials, adhesives, reinforced thermal insulation materials, and decorative materials.
Putty, as the main material for FRP repair, includes polyester resin putty, epoxy resin putty and some resin coating putty.
(1) Requirements for filling putty
1) It has good scratching properties, dry curing properties and sanding properties.
2) It has good filling properties and small shrinkage.
3) The adhesion to the substrate (the repaired FRP material) is better, and the putty layer should have a certain mechanical strength.
4) For repair parts that need to be painted, it is required to have low paint absorption and good adhesion to the painted layer.
(2) Putty preparation
1) Put the putty that has not been mixed with initiator on a flat plate and add initiator according to the prescribed amount.
2) Stir thoroughly with a scraper to make it evenly mixed.
3) Because putty is a fast curing material. The amount and operating time should be accurately estimated to avoid excessive mixing and waste.
4) The flat plate of the mixed putty can be a veneer, a metal plate or a glass steel plate, and it can be cleaned with acetone or paint thinner.
(3) Putty coating and scraping
1) Because the resin putty shrinks after curing, it is necessary to scrape more.
2) The scraper should be inclined about 45°.
3) Putty should be moderately soft and hard, if it is too hard, it is easy to produce holes, and if it is too soft, it is easy to sag.
4) When adding putty when the putty is used up in the middle, the scraper should be pulled from the front slightly.
5) Scrape putty on the rounded corners slowly to avoid forming cavities.
(4) Sanding putty
1) Dry abrasive cloth (paper) should be used after fully removing moisture. Emery cloth (paper) with scattered sand particles should not be used, because this kind of emery cloth (paper) will scratch other parts and make the sanding effect worse.
2) Water sandpaper must be polished with water. There should be no obvious heat during sanding.
3) Water sheet or rubber should be used as a pad to improve the efficiency and quality of polishing. The rounded corners should be polished with a tube as a pad.
4) Be careful when polishing, and observe the finish by using the hand feel and the reflection of light.
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