Important Factor Affecting The Application Of Carbon Fiber Roller
The appearance quality and fabrication accuracy of carbon fiber rollers are important factors that affect their application role.
In addition to the strength and large proportion of weight reduction effect that is better than steel, the appearance quality and fabrication accuracy of carbon fiber tubes are also important factors that affect their application role. The common production methods of carbon fiber round and square tubes are fiber surround method and molded-hot pressed can process, but the outstanding drawback of using these processes is that the appearance quality of the produced tubes is not good enough, and the shaped tubes made by prepreg layered pocket pressing process also have the same appearance drawback problem. The quality of the exterior not only affects the appearance of the pipe's finish, but also affects the size of the pipe and the mechanical equipment, so improving the quality and accuracy of the pipe is a major difficulty in the production of carbon fiber pipe.
A few solutions for this type of problem are summarized:
1. The causes of shortcomings.
Carbon fiber pipe fittings of the finished product's appearance of the shortcomings of the primary wrinkles, stripes and rich glue and other problems, tracing the occurrence of these problems is mainly concentrated in the prepreg layer of this link, in the use of carbon fiber composite material prepreg layer, if you can not exert sufficient tension pressure prepreg laminated block, it will make the lay on the composite material prepreg layer is relatively loose, the overall thickness will also exceed the thickness of the target pipe products. Therefore, in the molding process, the general treatment is to press to compress the layers of composite material and make the remaining resin flow out, but this pressurization will bring two kinds of shortening force. First, the carbon fiber composite material laminated block in the compression, the thickness of the tube will be thinner, the outer diameter becomes smaller, the perimeter is also reduced accordingly, the fiber along the ring is bound to relax, the carbon fiber is pressed to produce zigzag, folding; Second, in the carbon fiber tube molding process often requires the use of some auxiliary materials on the prepreg laminated block blank, such as breathable felt and vacuum bags, these auxiliary materials in the compression will also Cause wrinkles and stripes, curing will be embossed on the appearance of the composite material, and eventually form wrinkles.
2. Pre-compaction combined with temperature control.
The experience of the root of the summary, to solve the shortcomings of carbon fiber pipe appearance is an important step in the carbon fiber prepreg laying process, the combination of pre-compaction and appropriate temperature control. The detailed operating principle is in the process of laying material, each laying after a few layers, at a certain temperature and pre-compaction, exerting a certain pressure to compact the layers of fiber, this timely pre-compaction can prevent the fiber relaxation of the layers of the pile, in a certain pressure and temperature and other process conditions, to remove the remaining resin, air bubbles and low boiling point material in the prepreg blank, so that the blank dense and fundamentally reach the intended thickness. The pre-compacted blanks do not need to be glued during the curing process, and the resin content of the carbon fiber composite material and the thickness of the pipe can be controlled.
3. Use suitable mold material
Carbon fiber composite material pipe is not strictly controlled by the accuracy of the inner diameter scale, but has high requirements for the outer diameter, and the selection of the mold has a large impact on the outer diameter scale. For the fiber surround process or rolled process, because the fiber around the compression force, the requirements of the set of shape simply adhere to the same, so the selection of the original material in the core mold, it is better to select a metal material with outstanding rigidity, such as steel and hard aluminum, steel density and hardness are greater than hard aluminum, but the coefficient of thermal expansion of steel is not as hard aluminum. The high performance carbon tube products are cured at high temperature, if the hard aluminum core mold is used, the curing internal pressure that occurs through the thermal expansion of hard aluminum can progress the density and mechanical properties of the carbon tube. Therefore, in the process of encircling the high performance carbon tube, the core mold should be used hard aluminum. In order to help improve the quality of pipe forming, the principle of selecting the core mold is to use the elastic material with a large coefficient of linear expansion to make the mold, with a small coefficient of linear expansion of steel as an auxiliary mold, forming through the elastic material to transfer pressure and apply pressure, the experiment proves that this approach works ideally.
4. Using the uniform pressure of heat shrinkable sleeve
In addition to the above methods, the heat shrinkage process can also be used to improve the appearance of carbon fiber tubing quality and production accuracy. In high temperature curing, the heat shrink material can be useful to transfer the pressure of the hot press tank and evenly eliminate the impact of the vacuum bag and the wrinkles of the breathable felt on the carbon fiber composite material. For example, the heat shrinkage characteristics of the heat shrinkage sleeve is used to evenly compress the composite material. When the carbon fiber composite material prepreg is heated, the resin softens and the heat shrinkage tube will be shortened and deformed after reaching a certain shortening temperature, and the composite material stack block is compacted in the process of uniform caliber reduction. After the heat shrinkage process, the carbon fiber composite material tube is encapsulated and then cured, and the heat shrinkage tube is stripped and peeled off after the curing process. The detailed selection of what kind of heat shrink material, need to be based on the shortening temperature of the material, shortening rate and temperature resistance and several other parameters for comprehensive consideration. The technical staff of the emphasis, in the use of heat shrinkage process should be done to prevent the following two problems: First, the heat shrinkage when the heat shrinkage tube rupture; Second, the shortening will cause the outer layer of fiber dislocation. Therefore, we must control the temperature, heating must be uniform, try to make the shortening process becomes slow, reduce the intensity of shrinkage.
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