Gas auxiliary injection molding method of car roof handle

Abstract

The invention belongs to the technical field of car parts and particularly relates to a gas auxiliary injection molding method of a car roof handle. The method comprises the following steps that 1, molten plastic is injected into a die cavity through two or more pouring gates, and after injection of a die is full, pressure is maintained; 2, inert gas is injected into the molten plastic in the diecavity through two or more gas inlets, pressure of the injected inert gas is larger than storing pressure of injection molding, a part of the molten plastic in the die cavity returns to the pouring gates, and the hollow state is formed; and 3, the pressure is maintained, cooling is carried out, the die is opened, and a product is taken out.

Description

technical field

[0001] The invention belongs to the technical field of auto parts, and in particular relates to a gas-assisted injection molding method for an auto ceiling handle. Background technique

[0002] Gas-assisted injection molding (hereinafter referred to as "gas-assisted molding" or GAIM), as a relatively new polymer processing technology, was not widely used industrially until the end of the last century. Compared with conventional injection molding (CIM), gas-assisted molding has the advantages of saving raw materials, shortening molding cycle, reducing clamping force and good dimensional stability of parts. Usually in the gas-assisted molding process, it is necessary to use high-pressure inert gas as the penetrating gas to push and compress the polymer melt until the melt fills the entire mold cavity, and then the melt is gradually cooled and solidified under the pressure of the gas. After the temperature of the part drops to the demoulding temperature, the mo...

Examples

Embodiment 1

[0047] The 3 gates and 2 air inlets set in this embodiment are as follows: figure 1 As shown, molten polypropylene is injected into the mold cavity through gate 1, gate 2 and gate 3. The melt temperature is 230°C and the mold temperature is 60°C. After the mold is fully injected, hold the pressure for 2s. Close gate 1 and gate 3, then open air inlet 4 and air inlet 5, nitrogen is injected into the cavity melt through air inlet 4 and air inlet 5, and the nitrogen pressure in air inlet 5 is adjusted to 8MPa , the nitrogen pressure at the inlet 4 is 5MPa, the nitrogen temperature at the two inlets is 0°C, the gas injection time is 3s, the nitrogen pushes the fluid to flow, and the excess fluid flows back to the injection molding system from the gate 2, the plastic in the mold The melt is formed into a hollow state, and the pressure is kept for 6s, and then the mold is cooled in liquid nitrogen at -180°C, the mold is opened, and the product is taken out.

Embodiment 2

[0049] The 3 gates and 2 air inlets set in this embodiment are as follows: figure 1 As shown, the molten polypropylene is injected into the mold cavity through gate 1, gate 2 and gate 3. The melt temperature is 230°C, the mold temperature is 60°C, and the mold is filled with pressure for 6 seconds. Close gate 1 and gate 3, then open air inlet 4 and air inlet 5, nitrogen is injected into the cavity melt through air inlet 4 and air inlet 5, and the nitrogen pressure in air inlet 5 is adjusted to 8MPa , the nitrogen pressure at the inlet 4 is 5MPa, the nitrogen temperature at the two inlets is 0°C, the gas injection time is 3s, the nitrogen pushes the fluid to flow, and the excess fluid flows back to the injection molding system from the gate 2, the plastic in the mold The melt is formed into a hollow state, and the pressure is kept for 6s, and then the mold is cooled in liquid nitrogen at -180°C, the mold is opened, and the product is taken out.

Embodiment 3

[0051] The 3 gates and 2 air inlets set in this embodiment are as follows: figure 1 As shown, molten polypropylene is injected into the mold cavity through gate 1, gate 2 and gate 3. The melt temperature is 230°C and the mold temperature is 60°C. After the mold is fully injected, hold the pressure for 2s. Close gate 1 and gate 3, then open air inlet 4 and air inlet 5, nitrogen is injected into the cavity melt through air inlet 4 and air inlet 5, and the nitrogen pressure in air inlet 5 is adjusted to 8MPa , the nitrogen pressure at the inlet 4 is 5MPa, the nitrogen temperature at the two inlets is 30°C, the gas injection time is 3s, the nitrogen pushes the fluid to flow, and the excess fluid flows back to the injection molding system from the gate 2, the plastic in the mold The melt is formed into a hollow state, and the pressure is kept for 6s, and then the mold is cooled in liquid nitrogen at -180°C, the mold is opened, and the product is taken out.

technical field

[0001] The invention belongs to the technical field of auto parts, and in particular relates to a gas-assisted injection molding method for an auto ceiling handle. Background technique

[0002] Gas-assisted injection molding (hereinafter referred to as "gas-assisted molding" or GAIM), as a relatively new polymer processing technology, was not widely used industrially until the end of the last century. Compared with conventional injection molding (CIM), gas-assisted molding has the advantages of saving raw materials, shortening molding cycle, reducing clamping force and good dimensional stability of parts. Usually in the gas-assisted molding process, it is necessary to use high-pressure inert gas as the penetrating gas to push and compress the polymer melt until the melt fills the entire mold cavity, and then the melt is gradually cooled and solidified under the pressure of the gas. After the temperature of the part drops to the demoulding temperature, the mo...

Examples

Embodiment 1

[0047] The 3 gates and 2 air inlets set in this embodiment are as follows: figure 1 As shown, molten polypropylene is injected into the mold cavity through gate 1, gate 2 and gate 3. The melt temperature is 230°C and the mold temperature is 60°C. After the mold is fully injected, hold the pressure for 2s. Close gate 1 and gate 3, then open air inlet 4 and air inlet 5, nitrogen is injected into the cavity melt through air inlet 4 and air inlet 5, and the nitrogen pressure in air inlet 5 is adjusted to 8MPa , the nitrogen pressure at the inlet 4 is 5MPa, the nitrogen temperature at the two inlets is 0°C, the gas injection time is 3s, the nitrogen pushes the fluid to flow, and the excess fluid flows back to the injection molding system from the gate 2, the plastic in the mold The melt is formed into a hollow state, and the pressure is kept for 6s, and then the mold is cooled in liquid nitrogen at -180°C, the mold is opened, and the product is taken out.

Embodiment 2

[0049] The 3 gates and 2 air inlets set in this embodiment are as follows: figure 1 As shown, the molten polypropylene is injected into the mold cavity through gate 1, gate 2 and gate 3. The melt temperature is 230°C, the mold temperature is 60°C, and the mold is filled with pressure for 6 seconds. Close gate 1 and gate 3, then open air inlet 4 and air inlet 5, nitrogen is injected into the cavity melt through air inlet 4 and air inlet 5, and the nitrogen pressure in air inlet 5 is adjusted to 8MPa , the nitrogen pressure at the inlet 4 is 5MPa, the nitrogen temperature at the two inlets is 0°C, the gas injection time is 3s, the nitrogen pushes the fluid to flow, and the excess fluid flows back to the injection molding system from the gate 2, the plastic in the mold The melt is formed into a hollow state, and the pressure is kept for 6s, and then the mold is cooled in liquid nitrogen at -180°C, the mold is opened, and the product is taken out.

Embodiment 3

[0051] The 3 gates and 2 air inlets set in this embodiment are as follows: figure 1 As shown, molten polypropylene is injected into the mold cavity through gate 1, gate 2 and gate 3. The melt temperature is 230°C and the mold temperature is 60°C. After the mold is fully injected, hold the pressure for 2s. Close gate 1 and gate 3, then open air inlet 4 and air inlet 5, nitrogen is injected into the cavity melt through air inlet 4 and air inlet 5, and the nitrogen pressure in air inlet 5 is adjusted to 8MPa , the nitrogen pressure at the inlet 4 is 5MPa, the nitrogen temperature at the two inlets is 30°C, the gas injection time is 3s, the nitrogen pushes the fluid to flow, and the excess fluid flows back to the injection molding system from the gate 2, the plastic in the mold The melt is formed into a hollow state, and the pressure is kept for 6s, and then the mold is cooled in liquid nitrogen at -180°C, the mold is opened, and the product is taken out.

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