Composite inner cup and double-layer cup manufacturing method

A composite double-layer cup manufacturing method, comprising the steps of:

• S1) prefabricating the metal cup body:
• prefabricating the metal cup body, and forming an annular top convex ring at an opening of the metal cup body;
• S2) preparing a mold:
• setting up a female mold and a corresponding male mold, wherein the female mold has a mold cavity for holding the metal cup body, a cup rim space forming the cup rim portion is provided in the mold cavity corresponding to the top convex ring of the metal cup body, and a stepped bottom edge formed between the cup rim space and the mold cavity, wherein the male mold has a module arranged corresponding to the mold cavity, and a stepped pressing edge formed on the module corresponding to the cup rim space;
• S3) placing an upper ring and a lower ring:
• prefabricating the upper ring and the lower ring, wherein placing the lower ring on the bottom edge of the mold cavity, and placing the metal cup body into the mold cavity of the female mold, so that the top convex ring of the metal cup body is pressed against the lower ring, and then placing the upper ring on an inner end surface of the top convex ring;
• S4) closing the mold:
• closing the male mold to the female mold so that an underside of the top convex ring of the metal cup body is pressed against the lower ring and the upper ring is placed on an inner end surface of the top convex ring;
• S5) injecting molding:
• injecting plastic into the cup rim space through injection molding, allowing the plastic to melt and fuse together with the upper ring placed on the inner end surface of the top convex ring and the lower ring pressed against the underside of the top convex ring of the metal cup body, thereby integrally forming the cup rim portion, which encloses both the inner end surface and an outer side of the top convex ring to complete an inner cup;
• S6) prefabricating an outer cup:
• using a plastic material that is different from the metal cup body of the inner cup to make the outer cup;
• and
• S7) joining the two cups:
• placing the inner cup into the outer cup, and correspondingly combining the cup rim portion of the inner cup with the opening of the outer cup to complete the double-layer cup.