Method for producing seamless bimetal block

A method for producing a seamless bimetal block, comprising the steps of:

• providing a first metal block and a second metal block, the first metal block including a bottom portion and a sidewall portion, the bottom portion having a flat surface, the sidewall portion extending upward from a periphery of the flat surface, wherein the flat surface and the sidewall portion of the first metal block, and the second metal block are roughened;
• providing a mold including a lower mold and a mold cover, and placing the first metal block into the lower mold with the sidewall portion abutting one side of an inner surface of the lower mold so that the lower mold, the bottom portion, and the sidewall portion jointly define a bonding space, a volume of the second metal block being less than a volume of the bonding space, a height of the second metal block being less than a height of the sidewall portion;
• forming a bonding unit made of a polymer material in the bonding space and on the flat surface, the bonding unit including a bonding body, a first sharp portion, and a second sharp portion, the bonding body being in contact with the flat surface, and having a first welding surface that is adjacent to the sidewall portion and located below a top surface of the sidewall portion, and a second welding surface that is located below the first welding surface, the first sharp portion being located on the first welding surface, the second sharp portion being located on the second welding surface;
• and
• disposing the second metal block on top of the second sharp portion located on the second welding surface, covering the lower mold with the mold cover to press the second metal block, and performing an ultrasonic welding to melt the first sharp portion and the second sharp portion so that the mold cover fully closes the lower mold and so that the first sharp portion and the second sharp portion which are molten fill interspaces between the first metal block, the second metal block, and the bonding body, the first metal block and the second metal block being joined together to obtain the seamless bimetal block.