JPS6211607Y2 - - Google Patents

Description

[Detailed description of the invention] This invention provides a model of a dental prosthesis, a sprue, and a discharge gate made of a material that can be melted and flowed out, such as wax, in a pressure flask, and then embeds these in plaster, and after the plaster hardens, the wax is removed. A plaster mold surrounding a cavity shaped like a dental prosthesis is created by melting and pouring out the material, then heat-softened synthetic resin is injected and press-fitted through the sprue hole, and after the resin has cooled and hardened, a pressure flask is opened and the plaster mold is crushed. The present invention relates to a dental plaster-type pressure relief device used to obtain a resin tooth prosthesis.

When injecting resin into this type of plaster mold, it is actually very difficult to set the injection conditions because the plaster mold is weak in strength. Conventionally, injection conditions could be controlled according to the internal pressure of the plaster mold. Expensive computers are used and costs are inevitably high.

SUMMARY OF THE INVENTION An object of the present invention is to provide a pressure relief device that makes it possible to control the internal pressure of a plaster mold without using an expensive computer, thereby eliminating the above drawbacks.

The feature of this invention is that a pressure relief chamber is provided in the plaster-shaped prosthesis-shaped cavity through a vent hole, and the pressure relief chamber stores a piston pressed by an elastic device that can freely adjust the pressure. A resin extraction hole is provided in the chamber,
When the internal pressure of the plaster mold reaches a predetermined pressure, the resin is discharged from the extraction hole to prevent destruction of the plaster mold, and the resin in the pressure relief chamber flows back due to the pressing force of the piston to compensate for shrinkage. In order to facilitate the backflow of resin, an electric heater is installed in the pressure relief chamber.

Next, embodiments based on the features of the present invention will be described with reference to the accompanying drawings.

1 is a pressure-resistant flask that can be divided, and a plaster mold a
is stored.

2 is a dental prosthesis cavity formed in a plaster mold a, and a sprue hole (not shown) and a discharge gate hole 3 communicate with each other.

b is a pressure relief chamber communicating with the discharge gate hole 3, and is preferably made of metal, but may be made of other materials.

4 is a piston stored in the pressure relief chamber b, and is pressed by the bullet 5.

Reference numeral 6 denotes a resin extraction hole formed on the side of the pressure relief chamber b.

7 is a screw for adjusting the pressing force of the ammunition 5.

Reference numeral 8 denotes an electric heater mounted on the peripheral wall of the pressure relief chamber b.

9 is a resin denture.

When the softened pressure chamber b is heated by the heater 8, a softened high-strength synthetic resin other than acrylic resin is injected and press-fitted into the cavity from the sprue hole through the resin injection port (not shown) by an injection molding machine. 2 and then injected into the pressure relief chamber b through the discharge gate 3 to fill it.

Furthermore, the resin continues to be filled into the pressure relief chamber b by moving the piston 4 backward while resisting the pressing force of the bullet 5, but when the internal pressure of the plaster mold a increases and reaches a predetermined pressure, the resin continues to be filled in the pressure relief chamber b. The resin is discharged from the extraction hole 6 to suppress the internal pressure of the plaster mold a, and when the resin completely fills the cavity 2 and begins to harden, the heater 8 is pressed by the piston 4 due to the restoring force of the bullet 5. The resin in the pressure relief chamber b, which continues to maintain a molten state due to the heating, flows back into the cavity 2 from the discharge gate hole 3 to correct the shrinkage.

Note that the predetermined pressure can be freely set by adjusting the screw 7.

Furthermore, although a case is shown in which a spring is used for the elastic device 5, an appropriate elastic means such as rubber may be used.

Therefore, in the present invention, the internal pressure of the plaster mold a is adjusted by moving the piston 4 back and forth, and the discharge of the resin from the extraction hole 6 prevents the internal pressure from rising above a predetermined pressure, thereby eliminating the risk of destruction of the plaster mold a. removed.

Further, as the piston 4 moves forward, the resin in the pressure relief chamber b flows back, thereby reliably correcting the shrinkage, so that a product with high precision and a dense surface can be efficiently obtained, which has great practical effects.

[Brief explanation of the drawing]

The drawing shows an embodiment of the present invention and is a sectional view. a... Plaster mold, b... Relaxing pressure chamber, 2... Dental prosthesis cavity, 3... Discharge gate, 4... Piston, 5
...Ammunition, 6...Drilling hole, 7...Screw.

Claims (1)

[Scope of utility model registration request] In a pressure relief device for a plaster mold for obtaining a resin dental prosthesis by injection molding a resin into a plaster mold surrounding a prosthesis-shaped cavity and crushing the plaster mold, A pressure relief chamber is provided, and a piston pressed by a bullet is stored in the pressure relief chamber, and a resin extraction hole is provided in the pressure relief chamber. When the internal pressure of the plaster mold reaches a predetermined pressure, the resin is discharged from the extraction hole and the plaster is removed. A pressure relief device for a plaster mold for manufacturing a resin dental prosthesis, which prevents destruction of the mold and compensates for shrinkage by causing the resin in the pressure relief chamber to flow back due to the pressing force of a piston.