Patent ID: 8028888

Claim:
A method of joining a plurality of members to one another, comprising: providing a plurality of members each having a planar shape with opposed major surfaces and a terminal edge extending between said major surfaces; piling the plurality of members on one another so that opposed major surfaces of adjacent members contact one another to form a stack so that the terminal edges of the members are superposed and are all oriented in the same direction; restraining the members from both sides thereof; providing a tool having a pressure roller that is harder than the members and having an axis of rotation that is arranged parallel to the axis of the stack; rotating the pressure roller about its axis of rotation and pressing, at an area of contact, a circumference of the pressure roller against the terminal edges of the superposed members so that the terminal edges of the superposed members are rubbed to cause friction heating which leads to cause a plastic flow, wherein at said area of contact, the terminal edges of the superposed members are pressed by said circumference of the pressure roller and moved in a relative direction that is directly opposite to the direction in which the pressure roller is rotating, and wherein said pressing of said circumference of the pressure roller and said movement of the pressure roller in a relative direction that is directly opposite to said rotational direction of the pressure roller at said area of contact along the terminal edges of the superposed members rubs and joins the plurality of superposed members together at substantially only the terminal edges thereof.