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How are high-strength composite manhole covers made?

The composite material manhole cover is a kind of inspection manhole cover, and its characteristics are explained: the inspection manhole cover is compounded by a certain process using polymer as the matrix material, adding reinforcing materials, fillers, etc.
In fact, resin manhole cover (also called polymer glass fiber reinforced plastic manhole cover/composite material manhole cover) is a kind of manhole cover that uses glass fiber and its products (glass cloth, tape, felt, yarn, etc.) as reinforcing materials and synthetic resin as matrix material. It consists of unsaturated polyester resin, fillers, initiators, thickeners, low shrinkage additives, film mold agents, pigments and reinforcing materials, etc., and then is a new type of well cover product that is molded at high temperature.
Among the added materials, fiber reinforced materials (glass cloth, tape, felt, yarn, etc.) are the main ones, which are characterized by small specific gravity, large specific strength and specific modulus. For example, the composite material of carbon fiber and epoxy resin, its specific strength and specific modulus are several times larger than those of steel and aluminum alloy, and it also has excellent chemical stability, anti-friction and wear resistance, self-lubricating, heat resistance, fatigue resistance, resistance Creep, noise reduction, electrical insulation and other properties. The composite of graphite fiber and resin can obtain a material with an expansion coefficient almost equal to zero. Another feature of fiber reinforced materials is anisotropy, so the arrangement of fibers can be designed according to the strength requirements of different parts of the product. The aluminum matrix composites reinforced with carbon fibers and silicon carbide fibers can still maintain sufficient strength and modulus at 500 °C.
Composite manhole covers can be divided into BMC and SMC according to market demand, different production processes and materials:
BMC (DMC) materials are bulk molding compounds. It is often called unsaturated polyester bulk molding compound in China. The main raw material is a dough-like prepreg which is fully mixed by GF (chopped glass fiber), UP (unsaturated resin), MD (filler) and various additives. DMC materials were first used in the former West Germany and the United Kingdom in the 1960s, and then developed in the United States and Japan in the 1970s and 1980s, respectively. Because BMC bulk molding compound has excellent electrical properties, mechanical properties, heat resistance, chemical corrosion resistance, and adapts to various molding processes, it can meet the performance requirements of various products, and is widely used in automobile manufacturing, railway transportation , construction accessories, mechanical and electrical products and other fields.
SMC composites are sheet molding compounds. The main raw materials are composed of GF (special yarn), UP (unsaturated resin), low shrinkage additive, MD (filler) and various auxiliaries. It first appeared in Europe in the early 1960s, and around 1965, the United States and Japan successively developed this craft. In the late 1980s, my country introduced foreign advanced SMC production lines and production processes. SMC composite materials and their SMC molded products have excellent electrical insulation properties, mechanical properties, thermal stability, and chemical corrosion resistance. Therefore, the application range of SMC products is quite common. The current development trend is to replace BMC materials with SMC composites.
Now the application of our resin manhole covers plays a great role in our life, and the resin manhole covers stand out because of their self-cleaning function.
The use of resin manhole covers on the road has the characteristics of insulation, no noise, no recycling value and natural anti-theft. It is irreplaceable for cast iron manhole covers.
The resin manhole cover is made by a unique molding process, which makes the city look brand new. The service life is basically 20-50 years. The resin composite manhole cover formed by high temperature molding has the advantages of light weight and high strength, excellent fatigue resistance and damage safety. It has the advantages of simple molding, low grinding noise, good chemical corrosion resistance, good acid and alkali resistance and beautiful appearance, and the pollutants in the wastewater are further reduced.
Now on the market, the manhole covers produced by various composite manhole cover manufacturers are made of different materials, but several features are similar:
1. Strong anti-theft performance: Composite manhole covers are generally made of unsaturated resin, glass fiber and other materials through a special production process, and the products have no recycling value. Reinforcement is not so easy.
2. Service life: Through the use of high-performance resin, glass fiber and special production process formula, the penetration of the composite well cover in the glass fiber is ensured, and the adhesion between the two is greatly enhanced, so that the material will not be damaged under the action of cyclic load. Internal damage occurs, thus ensuring the service life of the product and the same advantages of other resin composite manhole covers, effectively eliminating the disadvantage of poor adhesion.
3. High temperature/low temperature resistance, good insulation performance and strong corrosion resistance: the product is corrosion-resistant, non-toxic and harmless. No metal additives. It can be used in complex and changeable, harsh and demanding places. The manhole covers produced by the Bester composite manhole cover manufacturers have been tested by the relevant national authoritative testing institutions, and have obvious acid and alkali resistance, corrosion resistance, anti-aging and many other indicators that meet the product quality standards.
4. Beautiful and practical, high-grade: according to the needs of high-end customers, we can make complex LOGO and a variety of colors on the surface of the same manhole cover personalized design, so that the pattern is delicate, the color is bright and clear. According to customer requirements, it can be made into various imitation stone appearances and colors that are the same as various stone pavements.
5. Strong bearing capacity: The bottom adopts a special design structure, and the continuous reinforcing fiber used is made of material to ensure that the fiber and glass fiber cloth are integrated, so that the product has a certain bearing capacity.
6. Environmental protection, non-slip, low noise: the manhole cover will not slip after the car is rolled, and there will be no adverse ear noise and pollution.
When installing a composite manhole cover, follow these four steps:
1. Before installation, the foundation of the manhole cover should be neat and firm, and the inner diameter, length and width should be determined according to the size of the manhole cover.
2. When installing the composite manhole cover on the cement road, pay attention to the wellhead masonry should be poured with concrete, and a concrete protection ring should be established on the periphery for maintenance for about 10 days.
3. When installing composite manhole covers on asphalt pavement, attention should be paid to avoid the construction machinery directly rolling the manhole cover and the well seat to avoid damage.
4. In order to maintain the beauty of the manhole cover and the clear handwriting and pattern, be careful not to stain the manhole cover when pouring asphalt and cement on the road surface.
development path:
(1) Its strength is second only to that of stone plastic manhole covers. It can carry more than 40 tons of vehicles.
(2) Its comprehensive performance is between the stone-plastic manhole cover and the concrete manhole cover, which is better than that of concrete; it can be used in occasions with high technical requirements for manhole covers.
(3) Its outstanding advantage is that it does not use steel skeleton reinforcement, but is reinforced with glass fiber composite, which belongs to GRC type products. Therefore, it has the advantage of being unaffected when the price of steel continues to rise. Because it does not contain a little iron, it is more anti-theft than stone plastic and fiber concrete manhole covers.
(4) Its curing speed is several times faster than that of fiber concrete, and it can be demolded in 8 hours. If it is produced in three shifts, it can be demolded three times in 24 hours. Although the amount of mold is more than that of stone plastic, it is only 1/6 of the fiber concrete manhole cover. It can also reduce mold investment. With an annual output of 10,000 sets of manhole covers, only 10 sets of molds are required.
(5) The composite manhole cover is ideal, more advanced, and incomparable with other molds (such as rubber molds, plastic molds, glass fiber reinforced plastic molds).
(6) In the continuous improvement and update of the composite manhole cover, various indicators have exceeded the industry standard of the Ministry of Construction, and basically reached the quality standard of my country’s manhole cover industry.

Ms.Serafina  +86 15102806197


Post time: Apr-23-2022