Introduction to HP-RTM Molding Process (Second Half)

2. Pressing process

1) Placement of preform

The brackets placed on the preform are stacked neatly, and the fiber preform is picked up by a mechanical arm with a suction cup. Transfer the preform to the open RTM molding mold, close the RTM injection mold, and lock the RTM molding mold with a locking mechanism.

2) Resin transfer injection

Under the condition that the injection cavity is always sealed, the mold is vacuumed, and the elastic resilience of the double rubber sealing ring is used to increase the mold closing gap. And the liquid low-viscosity resin is injected into the sealed injection mold at high temperature (mold temperature ≥150℃) from the bottom center of the mold under the action of high pressure injection machine.

A high-precision high-temperature injection machine is used to accurately measure and control the proportion of each component material in the resin system (main resin, curing agent, internal release agent, etc.), and the resin enters the mixing head of the injection machine under the action of high pressure metering pump, and the high pressure offset mixing in the mixing head, and the evenly mixed resin is quickly injected into the high-temperature mold cavity.

After the injection, the mold is completely closed. During the closing process, the mold is further squeezed and injected with the resin to fill and infiltrate the carbon fiber reinforced material, and it is quickly cured under high temperature and pressure.

3) In-mold spraying technology

After the curing of HP-RTM resin is finished, the closing gap of the mold is controlled again, and low viscosity mold surface resin is injected into the reserved side holes and flow channels, and the mold is completely closed again, and the gelcoat resin is extruded to fill the mold as much as possible, and a uniform resin film is sprayed on the surface of the product.

4) Demoulding and mold cleaning

After the resin curing of gelcoat is finished, the hydraulic press is opened from slow to fast, and the mechanical arm and its adsorption device are used to adsorb and fix the parts, the ejecting mechanism is opened to ejection the parts, and the ejecting parts are tightly adsorbed on the suction disc of the mechanical arm, and the residual resin flash in the mold is cleaned at the same time.

5) Cooling and shaping of parts

After demoulding, a mechanical arm and a suction cup are used to transfer the molding parts that are still in a high temperature state to the cooling tooling, and the parts are tightly adsorbed by vacuum, so that the parts are quickly cooled to room temperature.

6) Apply release agent

After demoulding, the mold is cleaned by brush, air pump, air nozzle, etc., the residual resin and fiber in the mold are removed, and the mold is wiped clean. The release agent is evenly coated on the surface of the mold to prepare for the next cycle of production.

3. Downstream process

Trim the contour of the workpiece

Transfer the cooling shaped composite sample to the machining center, in order to ensure the machining accuracy of the workpiece, the workpiece is directly moved to the machining tooling, and the robot and the machining tool are used to cut the excess flying edge and process edge of the workpiece.

2) Processing and dimensional inspection of the connecting structure of the parts

After the end of the cutting process, it is also necessary to process the connection and matching structure of the parts, such as the machining process of the positioning hole and the flatness of the matching surface, etc., the cutting tool needs to be replaced according to the situation to ensure the processing accuracy of the parts. After machining, it is also necessary to replace the inspection tools, check the dimensional tolerance of the parts, and get the composite parts that meet the requirements of use after the inspection.

HP-RTM molding process application

Automotive structural parts

Volvo's new XC90 crossover SUV is the first model to be produced on Volvo's new global "Scalable Vehicle Platform Architecture," or SPA, with a fully automated HP-RTM production line. In BMW i3 car body Life module structure of 34 pieces of carbon fiber composite materials, 13 of which are manufactured by HP-RTM process, BMW 7 series cars, body of 16 pieces of composite material technology, a total of 4 kinds of composite material molding technology, of which 3 pieces use HP-RTM process.

Battery box cover

New energy vehicle battery box cover, HP-RTM process is the most concentrated and most mature many domestic composite companies have battery box HP-RTM production line layout, and some companies have achieved mass production and delivery.

Sports and leisure

Carbon Fiber Composite (CFRTP) electric scooters - "The car in the pocket."

In order to achieve an "ultra-lightweight" and "strong" body, the main frame is made of carbon fiber thermoplastic composite (CFRTP), which is 10 times stronger than iron and 1/4 lighter, and the CFRTP frame with a plate thickness of only 3.3mm supports the whole. At the same time, due to the high elasticity of the body itself, the tires are soft and hold the road well.

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