Method for manufacturing a plastic hollow product using water soluble resin
OwnerJames J. Mauroinventor
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Abstract
A method for manufacturing a plastic hollow product with complicated geometry using water soluble resin. The method includes the steps of making a half shell of the core out of the water soluble resin, joining the half shells together into a piece by solvent welding, ultrasonic welding, vibration welding, or the like, overmolding the core with water resistant resin, and dissolving the core away from the overmolded product by spraying hot water thereto. The injection conditions such as injection time, injection speed, and injection pressure are varied in the respective zone which is divided into several divisions by same distance in the injection cylinder. Therefore, injection procedure is performed in a stepwise manner to make a hollow product.
Claims14
A method for manufacturing a plastic hollow core product using water soluble resin, which comprises the steps of:
- making first and second half shells of a high temperature resistant core by an injection molding process which employs an elongated injection cylinder having an inlet end and an outlet end, whereby for preparing each half shell said injection molding process comprises of:
- (1) heating the elongated injection cylinder to cause a temperature gradient along the elongated injection cylinder wherein the temperature at the inlet end is lower than the temperature at the outlet end;
- and (2) introducing water soluble resin through said injection cylinder and into a first mold cavity in a stepwise manner such that injection time, injection speed, and injection pressure through the elongated injection cylinder can be regulated;
- joining said half shells together into one piece by spreading a solvent on the contacting surfaces of said half shells and then drying the joined core for approximately 1 to 24 hours while applying pressure of approximately 30 to 140 psi thereon;
- making an overmolded core product by positioning said core into a second mold cavity, and thereafter injecting under high pressure a water resistant resin around said core by a process which employs the elongated injection cylinder, whereby the step of injecting said water resistant resin comprises of:
- (1) heating the elongated injection cylinder to cause a temperature gradient along the elongated injection cylinder wherein the temperature at the inlet is lower than the temperature at the outlet;
- and (2) introducing said resistant resin through said injection cylinder and into the second mold cavity in a stepwise manner such that injection time, injection speed, and injection pressure through the elongated injection cylinder can be regulated and then cooling the overmolded core product;
- and
- dissolving said water soluble resin from said overmolded core product with hot water.
Dependencies are inferred from the claim text.