Ultrasonic welding method, structure welded by ultrasonic welding method, and ultrasonic welding device

An ultrasonic welding machine comprising:

• an anvil on which two or more thermoplastic resin members are placed;
• a tool horn having a pressing surface, the pressing surface descending and being pressed onto upper surfaces of the two or more thermoplastic resin members while vibrating ultrasonically in a direction not perpendicular to but along the upper surfaces;
• a press configured to cause the pressing surface of the tool horn to descend and press onto the upper surfaces of the two or more thermoplastic resin members;
• and
• a controller configured to control, in accordance with a sinking amount of the tool horn, ultrasonic vibration of the tool horn and pressing of the tool horn by the press,
• the controller being configured to control welding of the two or more thermoplastic resin members by controlling the tool horn so as to apply a pressing force that presses the upper surfaces of the two or more thermoplastic resin members, while keeping the tool horn vibrating ultrasonically, to melt a vicinity of the upper surfaces of the two or more thermoplastic resin members, and configured to stop the descending of the tool horn and cause the tool horn to ascend when the sinking amount of the tool horn reaches a predetermined sinking amount, thereby forming a welded structure part on an unwelded structure part, and welding the two or more thermoplastic resin members in an overlap structure including the welded structure part arranged on the unwelded structure part.

A structure obtained by welding two or more thermoplastic resin members placed on an anvil, using a tool horn configured to vibrate ultrasonically in a direction not perpendicular to but along upper surfaces of the two or more thermoplastic resin members, wherein

• the structure has an overlap structure including a welded structure part arranged on an unwelded structure part,
• the welded structure part is formed by applying, to the upper surfaces of the thermoplastic resin members, ultrasonic vibration energy in the direction not perpendicular to but along the upper surfaces of the thermoplastic resin members so as to melt a vicinity of the upper surfaces of the thermoplastic resin members, the welded structure part corresponding to an area extending from the upper surfaces of the two or more thermoplastic resin members, through an interface, which is a target of welding, between the two or more thermoplastic resin members, to a predetermined depth not reaching lower surfaces of the two or more thermoplastic resin members,
• the unwelded structure part corresponds to an area to which the ultrasonic vibration energy is not applied, the unwelded structure part extending from the predetermined depth, not reaching the lower surfaces of the two or more thermoplastic resin members, to the lower surfaces, and
• a surface state of the lower surfaces of the structure having the overlap structure including the welded structure part arranged on the unwelded structure part is kept unchanged before and after the welding.