CN100368185C - Rapid RTM manufacturing method for resin-based advanced composites - Google Patents

Abstract

The invention discloses a rapid RTM manufacturing process of resin-based advanced composite materials, which belongs to the composite material manufacturing process. The process steps: a. use CAD/CAM software and RP technology to prepare the required prototype; b. use the prototype to reproduce the corresponding room temperature vulcanized silicone rubber mold; c. Prefabrication, mold closing, sealing; e resin degassing; f placing the mold in a high-pressure water tank; g closing the high-pressure water tank, filling the high-pressure water tank with degassed water; h injecting resin into the mold with high pressure; i The high-energy focused ultrasonic device works to make it heat up and solidify; j after the curing is completed, turn off the ultrasonic; k release the air and water, and open the high-pressure water tank; l move the mold out of the high-pressure water tank, and take the composite material part out of the mold; m pair the composite Parts of material are cleaned and inspected. The method can quickly obtain the mold, quickly cure the resin, have less energy consumption, high production efficiency, and can obtain high-quality products.

Description

Rapid RTM manufacturing method for resin-based advanced composites

1. Technical field

The present invention relates to rapid RTM manufacturing methods for resin-based advanced composite materials. The difference from the general RTM process is that it uses silicone rubber as the mold material, uses RP (rapid prototyping) technology and silicone rubber mold technology to quickly manufacture RTM molds, and adopts high-energy focused ultrasound-high-pressure water tank curing process for rapid curing. It belongs to the field of composite material manufacturing technology.

2. Background technology

Resin-based advanced composite materials reinforced with high-performance glass fibers, carbon fibers, and aramid fibers have a series of advantages such as high specific strength, high specific stiffness, material designability, fatigue resistance, and wear resistance, but there are also high raw material costs. , The disadvantage of complex preparation process. High manufacturing costs are the main reason why advanced composite materials are expensive.

RTM process is an important method to manufacture complex and irregular parts of advanced composite materials. The specific process is to place fiber prefabricated parts in the inner cavity of the mold, inject resin into the mold, and then heat the resin to make it solidify to obtain the required parts. The RTM process is a promising low-cost manufacturing process.

For high-performance aerospace composites, fiber preforms are generally textile preforms with a high fiber volume fraction. At this time, the RTM process requires a higher resin injection pressure, which is 1-7 atmospheres. The rigidity of the mold must be adapted to it, which puts higher requirements on the mold material, making the processing of the mold laborious and laborious. The resin in the mold is cured. At present, the method of heating the mold is mainly used to transfer heat to the resin to heat up and solidify. The heating speed is slow and the energy consumption is large.

Silicone rubber, room temperature vulcanized, can be molded quickly and is suitable for making complex molds, so it has become a commonly used rapid mold (RM) material. Moreover, silicone rubber is a good ultrasonic sound-transmitting material. After the high-energy ultrasound is focused, the energy density in the focused area is very high, the thermal effect is obvious, and the focused ultrasound has a strong penetrating ability. In medicine, high-energy ultrasound is used to penetrate the human skin and focus on the cancerous parts of the body. After 0.2-2 seconds of continuous irradiation, the lesion area will be heated by 65-80°C to kill cancer cells.

Focus the high-energy ultrasound on the resin, and the resin in the focused area will heat up and solidify within a short time. Silicone rubber is a good ultrasonic sound-transmitting material. High-energy focused ultrasound can penetrate the silicone rubber mold, irradiate and scan the resin in it, and make it heat up and solidify.

3. Contents of the invention

The invention provides a fast RTM manufacturing process for manufacturing resin-based advanced composite materials that can quickly obtain required molds, fast-cure resin, consume less energy, and be low-cost.

Concrete steps of the present invention are:

a. Use CAD/CAM software and RP (rapid prototyping) technology to prepare the required prototype.

b. Use the prototype and silicone rubber soft mold technology to reproduce the corresponding room temperature vulcanized silicone rubber mold.

c. Coat the inner surface of the mold with release agent.

d. Place the fiber prefabricated part in the mold, close the mold and seal it.

e. Resin degassing. If curing agent is needed for resin curing, it is necessary to add curing agent and mix evenly.

f. Place the mold in a high-pressure water tank, connect the mold gate to the resin injection pipe, and connect the riser to the exhaust pipe;

The injection pipe is connected to the resin injection equipment, and the exhaust pipe is connected to the vacuum pump.

g. Close the high-pressure water tank and fill the high-pressure water tank with degassed water.

h. Use resin injection equipment to inject resin into the mold through the resin injection pipe of the high-pressure water tank; the vacuum pump extracts the air in the mold. When the resin is injected, increase the water pressure to balance the high pressure of resin injection that the mold is subjected to and eliminate the deformation of the mold. After the resin is full, the resin injection equipment stops injecting. Reduce water pressure.

i. The high-energy focused ultrasound device inside the water tank works; with degassed water as the transmission medium, the high-energy focused ultrasound penetrates the silicone rubber, irradiates and scans the resin in the inner cavity of the mold, and makes it heat up and solidify. There are two ways of heat curing. Method 1: High-energy focused ultrasound acts on a certain part of the inner cavity of the mold to properly heat up the resin in the focused area; the focused area is then moved to an adjacent area, and the resin is heated to the same temperature; the focused area is scanned Inner cavity of the mold, so that all resins reach the same temperature; repeat the above process, make the resin in the inner cavity of the mold heat up according to the specified temperature change curve, until it reaches the curing temperature. Method 2: Continuously irradiate a certain area with high-energy focused ultrasound to heat up and cure the resin in this area; then move to the next area to heat up and cure the resin in this area until all the resin in the cavity of the mold is cured.

j. After the curing is completed, turn off the ultrasound. Cool molds and composite parts with deaerated water.

k. Release the air and water, and open the high-pressure water tank.

l. Move the mold out of the high-pressure water tank, and take out the cured composite material part from the mold.

m. Clean and inspect composite parts.

Before the resin is injected into the mold, it must be degassed and mixed with the curing agent evenly. The degassing steps are:

a. The resin is injected into a sealed container, which is made of sound-transmitting material; the resin occupies an appropriate volume of the container; if the resin is cured and a curing agent is required, an appropriate amount of curing agent must be added;

b. The sealed container is placed in the working water tank of the ultrasonic cleaner;

c. Vacuumize the sealed container so that the air pressure in the container is properly lower than the external atmospheric pressure;

d. Start the ultrasonic cleaning machine. Low-frequency ultrasound penetrates the container material, causing cavitation effects in the resin and curing agent. The resulting bubbles rise, collapse and the gas escapes. Ultrasonic work until the cavitation disappears. The curing agent and the resin can also be mixed evenly under the action of the acoustic impulse flow induced by the ultrasonic wave.

The positive effect that the present invention has has:

a. The required mold can be obtained quickly. CAD/CAM/RP technology can quickly obtain the required prototype, and room temperature vulcanized silicone rubber can quickly reproduce the corresponding mold;

b. It can quickly cure the resin. High-energy focused ultrasound passes through the silicone rubber and irradiates the resin. The strong thermal effect makes the resin heat up rapidly until it is cured. Curing time, energy consumption is much less than heating.

c. During the curing process of the resin, the temperature of the resin in each part of the cavity of the mold can be precisely controlled. By optimizing the curing process, the residual stress inside the cured composite part can be reduced.

d. Partial curing is possible. It is a very suitable curing technology for the so-called "co-injection RTM" process with different resins in the same mold.

4. Description of drawings

Figure 1 is a schematic diagram of a tank body of a high-pressure water tank.

Figure 2 is a schematic diagram of a high-pressure water tank.

Label names in the figure: 1. High-energy focused ultrasonic power supply; 2. High-pressure water tank body; 3. Resin injection equipment; 4. High-energy focused ultrasonic emitter; 5. Resin injection tube; 6. Cart; 7. Silicone rubber mold; 8. Exhaust pipe; 9. Three-coordinate motion platform; 10. Vacuum pump.

Figure 3 is a schematic diagram of the resin degassing device.

Label names in the figure: 11. Ultrasonic cleaning machine sink; 12. Resin; 13. Sealed container; 14. Exhaust pipe; 15. Vacuum pump;

5. Specific implementation

Figure 1 and Figure 2 are schematic diagrams of the high-pressure water tank body and the composition of the high-pressure water tank. That is, in the high-pressure water tank, the mold 7 is clamped on the dolly 6, and the dolly is fixed. The high-energy focused ultrasonic transmitter head 4 is installed on a three-coordinate motion platform 9 capable of X, Y, and Z three-axis motion, and the ultrasonic power supply 1 is installed outside the tank body 2 of the high-pressure water tank. The three-coordinate motion platform 9 moves according to instructions.

FIG. 3 is a schematic diagram of a resin degassing device, including an ultrasonic cleaner water tank 11 , a resin 12 , a sealed container 13 , a suction pipe 14 and a vacuum pump 15 .

Below in conjunction with above-mentioned accompanying drawing, give two embodiments, describe the specific implementation mode of the present invention:

Embodiment 1

In CAD/CAM software, carry out the three-dimensional modeling of the part prototype. And use RP (rapid prototyping) technology to make the corresponding prototype. Then remake the corresponding room temperature vulcanized silicone rubber mold. Apply silicone oil on the inner surface of the mold as a release agent. Place the carbon fiber three-dimensional prefabricated part in the mold, close the mold, and seal it. The mold is clamped on the trolley in the high-pressure water tank to fix the trolley. Connect the resin gate and riser of the mold to the resin injection pipe and the exhaust pipe of the high-pressure water tank respectively. Close the high-pressure water tank, fill it with degassed water, and adjust the water pressure to 1.5 atmospheres (assuming that the outside world is 1 atmosphere at this time).

Mix the epoxy resin with the anhydride curing agent (mass ratio: 10:7), and put it into a closed container, occupying half the volume of the container. The container is made of sound-permeable material ABS resin. Place the container in the working sink of the ultrasonic cleaner. Vacuumize the airtight container to 0.1 atmosphere. Turn on the ultrasonic cleaning machine, low-frequency ultrasonic waves penetrate the container wall, and act on the mixture of epoxy resin and curing agent. Cavitation occurs in it, the generated bubbles rise up, burst and the gas escapes. When the working time is up, turn off the ultrasonic cleaner. At this time, the epoxy resin and the curing agent are also mixed evenly under the action of the acoustic impulse flow caused by the ultrasound.

The epoxy resin that has been degassed and evenly mixed with an anhydride curing agent is used to fill the cavity of the mold with a high pressure of 7 atmospheres. The vacuum pump works to reduce the air pressure in the mold cavity. During the resin injection process, increase the water pressure in the high-pressure water tank to balance the high pressure of resin injection on the silicone rubber mold and reduce mold deformation. After the resin is full, the resin injection equipment stops injecting. Reduce the water pressure to 1.5 atmospheres. Start the high-energy focused ultrasonic system, use degassed water as the transmission medium, the high-energy focused ultrasonic head emits ultrasonic waves, pass through the silicone rubber mold, and irradiate the inner cavity of the mold to heat up the resin at the focus. Driven by the three-coordinate motion platform, the high-energy focused ultrasonic head sweeps the cavity space of the mold in sequence, and the focusing area makes all the resins in the cavity of the mold heat up to the same temperature. Repeat this process to gradually increase the temperature of the resin in the cavity of the mold according to the curing specification until it is cured.

Turn off the ultrasonic system, release water from the high-pressure water tank, and take out the mold. The formed part is removed from the mold, cleaned and inspected.

Embodiment 2

In CAD/CAM software, carry out the three-dimensional modeling of the part prototype. And use RP (rapid prototyping) technology to make the corresponding prototype. Then remake the corresponding room temperature vulcanized silicone rubber mold. Apply silicone oil on the inner surface of the mold as a release agent. Place the carbon fiber three-dimensional prefabricated part in the mold, close the mold, and seal it. The mold is clamped on the trolley in the high-pressure water tank to fix the trolley. Connect the resin gate and riser of the mold to the resin injection pipe and the exhaust pipe of the high-pressure water tank respectively. Close the high-pressure water tank, fill it with degassed water, and adjust the water pressure to 1.5 atmospheres (assuming that the outside world is 1 atmosphere at this time).

Mix the epoxy resin with the modified amine curing agent (mass ratio is 4:1), and put it into an airtight container, occupying half the volume of the container. The container is made of sound-permeable material ABS resin. Place the container in the working sink of the ultrasonic cleaner. Vacuumize the airtight container to 0.1 atmosphere. Turn on the ultrasonic cleaning machine, low-frequency ultrasonic waves penetrate the container wall, and act on the mixture of epoxy resin and curing agent. Cavitation occurs in it, the generated bubbles rise up, burst and the gas escapes. When the working time is up, turn off the ultrasonic cleaner. At this time, the epoxy resin and the curing agent are also mixed evenly under the action of the acoustic impulse flow caused by the ultrasound.

The epoxy resin that has been degassed and evenly mixed with the modified amine curing agent is used to fill the inner cavity of the mold with a high pressure of 7 atmospheres. The vacuum pump works to reduce the air pressure in the mold cavity. During the resin injection process, increase the water pressure in the high-pressure water tank to balance the high pressure of resin injection on the silicone rubber mold and reduce mold deformation. After the resin is full, the resin injection equipment stops injecting. Reduce the water pressure to 1.5 atmospheres. Start the high-energy focused ultrasonic system, use degassed water as the transmission medium, the high-energy focused ultrasonic head emits ultrasonic waves, pass through the silicone rubber mold, and irradiate the inner cavity of the mold to heat up the resin at the focus. Driven by the three-coordinate motion platform, the high-energy focused ultrasonic head scans the inner cavity of the mold layer by layer from bottom to top. The resin is cured in one place by heat, and then moved to the adjacent part, where it is cured by heat. Repeat this process to cure all the resin in the cavity of the mold.

Turn off the ultrasonic system, release water from the high-pressure water tank, and take out the mold. The formed part is removed from the mold, cleaned and inspected.

Claims (2)

1. A rapid RTM manufacturing method of resin-based advanced composite material, characterized in that it has the following steps: a. Use CAD/CAM software and rapid prototyping (RP) technology to prepare the required prototype; b. Use the prototype to reproduce the corresponding room temperature vulcanized silicone rubber mold; c. Coating release agent on the inner surface of the mold; d. Place the fiber prefabricated part in the mold, close the mold and seal; e. Resin degassing, if curing agent is needed for resin curing, curing agent needs to be added and mixed evenly; f. Place the mold in a high-pressure water tank, connect the mold gate to the resin injection pipe, and connect the riser to the exhaust pipe; the injection pipe is connected to the resin injection equipment, and the exhaust pipe is connected to the vacuum pump; g. Close the high-pressure water tank and fill the high-pressure water tank with degassed water; h. Use resin injection equipment to inject resin into the mold with high pressure through the resin injection pipe of the high-pressure water tank; the vacuum pump extracts the air in the mold, and when the resin is injected, the water pressure is increased to balance the high pressure of resin injection on the mold to eliminate After the mold is deformed and the resin is filled, the resin injection equipment stops the injection and reduces the water pressure; i. The high-energy focused ultrasound device inside the water tank works; with degassed water as the transmission medium, the high-energy focused ultrasound penetrates the silicone rubber, irradiates and scans the resin in the inner cavity of the mold, and makes it heat up and cure. There are two heating and curing methods: 1. High-energy focused ultrasound acts on a certain part of the inner cavity of the mold to heat up the resin in the focused area; the focused area is then moved to the adjacent area, and the resin is heated to the same temperature; the focused area scans the mold cavity, so that all the resin reaches the same temperature; repeat the above process, so that the resin in the cavity of the mold is heated up according to the specified temperature change curve until it reaches the curing temperature; method 2, high-energy focused ultrasound continuously irradiates a certain area, so that the resin in this area Heat up and solidify; then move to the next area to make the resin in this area heat up and solidify; until all the resin in the cavity of the mold is solidified; j. After the curing is completed, turn off the ultrasound. Use degassed water to cool molds and composite parts; k. Release the air and water, and open the high-pressure water tank; l. Move the mold out of the high-pressure water tank, and take out the cured composite material parts from the mold; m. Clean and inspect composite parts; 2. The rapid RTM manufacturing method of resin-based advanced composite materials according to claim 1, wherein the resin degassing step is: a. Put the resin into a sealed container, which is made of sound-transmitting material; the resin occupies an appropriate volume of the container; if the resin needs a curing agent for curing, it is necessary to add an appropriate amount of curing agent; b. The container is placed in the working water tank of the ultrasonic cleaner; c. Reduce the air pressure in the container to make it less than the external atmospheric pressure; d. Start the ultrasonic cleaning machine, the low-frequency ultrasound will produce cavitation effect in the resin and curing agent, the generated bubbles will rise and burst, and the gas will escape until the cavitation phenomenon disappears; the curing agent and resin can also be mixed evenly under the action of ultrasonic waves .

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