Abstract: A rotary cutting apparatus includes a pair of cutting tools each having a cutting blade along a tip end of its outer peripheral portion having a mountain-shaped cross section, and cuts a cylindrical material into pieces with a predetermined width by sandwiching the cylindrical material between the cutting blades so the cutting blades are respectively placed on inner and outer peripheries of the cylindrical material, and relatively rotating and moving the pair of cutting tools along an entire circumference of the cylindrical material. A second imaginary line connecting an axial center of the cylindrical material and an axial center of the inner peripheral-side cutting tool is shifted in a circumferential direction of the cylindrical material about the axial center of the cylindrical material with respect to a first imaginary line connecting the axial center of the cylindrical material and an axial center of the outer peripheral-side cutting tool.

Abstract: A rotary cutting apparatus includes a pair of cutting tools each having a cutting blade along a tip end of its outer peripheral portion having a mountain-shaped cross section, and cuts a cylindrical material into pieces with a predetermined width by sandwiching the cylindrical material between the cutting blades so the cutting blades are respectively placed on inner and outer peripheries of the cylindrical material, and relatively rotating and moving the pair of cutting tools along an entire circumference of the cylindrical material. A second imaginary line connecting an axial center of the cylindrical material and an axial center of the inner peripheral-side cutting tool is shifted in a circumferential direction of the cylindrical material about the axial center of the cylindrical material with respect to a first imaginary line connecting the axial center of the cylindrical material and an axial center of the outer peripheral-side cutting tool.

Abstract: An endless metal belt including a ring formed by laminating endless metal plates; and multiple elements continuously attached to the ring. Each of the elements has a body, a head connected to the body by a pillar, and slots formed between the body and the head on left and right sides of the pillar, respectively, for receiving the ring. The elements satisfy the equations (h/t)<1 and (S/h)>40, where h is a width of the slots, t is a plate thickness of the elements, and S is an area of the head.

Abstract: An endless metal belt including a ring formed by laminating endless metal plates; and multiple elements continuously attached to the ring. Each of the elements has a body, a head connected to the body by a pillar, and slots formed between the body and the head on left and right sides of the pillar, respectively, for receiving the ring. The elements satisfy the equations (h/t)<1 and (S/h)>40, where h is a width of the slots, t is a plate thickness of the elements, and S is an area of the head.

Abstract: An aluminum alloy material for the shutter of flat recording medium cassettes. The shutter is light in weight and smoothly slidable, has good corrosion resistance and durability, and protects itself against staining with fingerprints. The aluminum alloy contains 3.0-6.0% Mg (by weight) and one or more than one optional elements of Mn.ltoreq.1.5%, Cr.ltoreq.0.3%, Cu.ltoreq.0.5%, and Ti.ltoreq.0.1%, with the balance being aluminum and inevitable impurities, and has a tensile strength of 310-410 MPa and a yield strength of 250-370 MPa. The aluminum alloy material is formed from a rolled sheet of said aluminum alloy by coating the sheet with a plastic film not thicker than 5 .mu.m. The rolled sheet undergoes intermediate annealing at higher than the recrystallization temperature, final cold rolling, and stabilizing heat treatment.