Among the RV users or intended users we came into contact with, they asked the most questions about the body: Is the outer panel of the body aluminum plate or glass fiber reinforced plastic, and is there a skeleton? Then let's talk about the wallboard structure of the RV. Almost all the wallboard we can see is a sandwich composite structure. This term comes from western countries. How much do they eat every day? Sandwiches are the mainstay, and the wallboard structure of the RV is very similar to sandwiches. Just turn two pieces of bread into aluminum plate or glass fiber reinforced plastic, and turn ham and vegetables sandwiched between them into various materials with sound insulation, insulation and waterproof functions. In China, we call it the sandwich panel, which is the same, but with a different name.
Generally speaking, most of the wallboard of RV has a skeleton, just like we build a house, especially the side wallboard plays a load-bearing role, which determines the load-bearing, strength, waterproof and thermal insulation of the whole RV after molding. As mentioned above, RV wallboard is made of sandwich composite structure. Since it is a sandwich structure, we should not only pay attention to the materials on both sides of the wall, but also pay attention to the core. When it comes to wallboard, the main thing is the self-propelled C-type RV. The wallboard on both sides is nothing more than FRP and aluminum plate, and the sandwich material is the key, because it has too many filling materials, different prices and good quality.
Here, we should walk out of a misunderstanding. We often think that aluminum plate is superior to FRP, which is obviously one-sided. Glass fiber reinforced plastic and aluminum plate at the same price have their own advantages and disadvantages, but aluminum plate and glass fiber reinforced plastic at different prices are not comparable. At present, there are some integrated abrasives and some integrated abrasives in common automobile bodies in China, but the forehead needs to be redesigned. Most of the exterior walls of some carriages are aluminum plates, and only the foreheads are made of glass fiber reinforced plastic. The reason is that the strength of FRP external wall panels is good, which can prevent the roof from being damaged in hail weather and avoid leaving traces of hail damage, while the aluminum materials of other side walls can give full play to their advantages of good texture and easy repair.
●EPS？ Expanded polystyrene
▲EPS foam+wood skeleton
Having said that, let's take a look at the internal structure of the board of directors. The RV was also a sandwich composite structure in its early manufacture, but the skeleton in the composite structure was a wooden frame filled with EPS (Expanded Polystyrene). Later, more and more manufacturers gave up the manufacturing process of EPS+ wood because this method has serious defects. If water seeps into the room through the edge of the roof or window, eps foam will be absorbed and lead to wood deformation and corruption. Therefore, wallboard has lost its bearing capacity, and if it is not found in time in the early stage, it may lead to considerable damage and expensive maintenance costs.
●XPS？ polystyrene
▲XPS (polystyrene)
XPS (polystyrene) is the most popular filler that we can see in many RV wallboard at present, and XPS (polystyrene) is increasingly used as a substitute for thermal insulation materials. XPS is a little more expensive and heavier than EPS, but it doesn't absorb water. XPS has a closed-cell structure, which means it has a smooth and uniform surface. So, how can this material be visually distinguished? XPS is usually blue, green or pink. XPS is relatively compressive and hard, so it needs less reinforcement.
●PU polyurethane
▲ The yellow material is PU (polyurethane)
▲ Schematic diagram of bonding between carriage plates.
▲ The appearance of adhesion between actual carriage plates.
PU (polyurethane) is now also used in the manufacture of RV wallboard. PU (polyurethane) is often not used alone, but is sealed between sandwich panels together with other materials, which is common in the joints between plates. Highly compressed PU polyurethane is very stable and corrosion resistant. Strong screws are also provided, which is very important for corner connection between roof, wall and floor. Usually, a combination of screws and sealant is used for encapsulation.
▲XPS material floor
In fact, PU and XPS have little difference in thermal insulation performance, which is also suitable for RTM foaming (RTM refers to a resin pouring process) that some manufacturers rely on, and is also widely used in some luxury European-style RVs. In fact, it is a special-shaped material of XPS foam, which has better thermal insulation performance, so the price is often higher. Today, more and more manufacturers begin to use "wood-free technology" for advertising, such as brands owned by Nisman and Heim. Strictly speaking, wood-free technology is not completely without wood structure, and sometimes some wood reinforcement materials are used in the structure, especially at the compression point. The combination of XPS and high compression PU strip is adopted by more and more touring cars as reinforcing materials, and the shell of the roof and floor is usually made of hail-proof and corrosion-resistant FRP.
●PE？ polyethylene
▲PE？ Polyethylene material
PE？ Polyethylene is very soft and easy to process. Although PE is relatively heavy and its thickness is relatively small, it can provide good thermal insulation and sound insulation. In terms of price, PE is slightly higher, which is a bit like XPS and does not absorb water. PE is usually dark gray to black, which is often used in the lining of B-type campers to achieve good heat insulation effect, and some users of self-modified RVs also like it.
●FEF？ Flexible foam material
FEF？ Flexible foam material is a relatively new thermal insulation material, and it is more and more used to modify recreational vehicles. It is generally used in high-end campers in batches, such as Volkswagen California T6 camper and Mercedes-Benz Kyle Polo, which are popular in Europe in recent years. The so-called flexible foam material (FEF) has high flexibility, the best insulation performance and very light weight. This material does not absorb water, but also has the function of noise reduction and provides a protective coating to prevent the invasion of bacteria and mold.
▲PVC structural foam board
Summary: Different insulating materials have different properties, and the best material combination that meets all requirements has not been found yet. However, we can find that the traditional board made of wood and EPS foam is gradually becoming a thing of the past and will gradually withdraw from the historical stage. Whether made in Europe, America or China, the most common intermediate materials of sheet are XPS and PU, or their mixture. Of course, some cars also use PVC foam board, which is relatively low in cost and easy to process, and is also a good profile. We don't have to worry about whether the glass fiber reinforced plastic or the aluminum material is good for the exterior panel of RV. Let's just say they have their own advantages and disadvantages. In the final analysis, the decisive factor is not the surface, but the internal "core". (Text /2 1rv? Wang Hailong)
Note: The above information is obtained through various inquiries and may be incomplete or biased. If you have any questions, readers can raise them and we will correct them in time.
This article comes from car home, the author of the car manufacturer, and does not represent car home's position.