Die set for tearing sheet material and method for tearing sheet material
AssigneeNHK Spring Co., Ltd.
InventorKoichi IMOTO
Life of this patent
Estimating the term…
Abstract
A die set includes a first die unit which fixes a first portion of a sheet material and a second die unit which fixes a second portion of the sheet material. A fulcrum portion is formed at a position facing the sheet material. The fulcrum portion has a first support surface and a second support surface extending in an oblique direction toward a weakened portion. The first support surface generates a tensile force to tear off a part near one end of the weakened portion while the amount of movement of the second die unit relative to the first die unit is small. The second support surface generates a tensile force to tear off a part near the other end of the weakened portion as the amount of relative movement of the second die unit increases.
Claims4
A die set comprising:
- a first die unit which fixes a first portion of a sheet material;
- a second die unit which fixes a second portion of the sheet material and moves relative to the first die unit in a thickness direction of the sheet material;
- and
- a fulcrum portion located to face the sheet material, which is brought into contact with the sheet material when the first die unit and the second die unit move relative to each other in the thickness direction of the sheet material, and generates a tensile force to tear the sheet material, wherein
- the fulcrum portion includes:
- a first support surface which is located at a position to generate a tensile force to tear a part near one end of the weakened portion when an amount of movement of the second die unit with respect to the first die unit is small, and
- a second support surface which is located at a position to generate a tensile force to tear a part near the other end of the weakened portion when an amount of movement of the second die unit with respect to the first die unit increases.
A method for tearing a sheet material, comprising:
- fixing a first portion of the sheet material by a first die unit;
- fixing a second portion of the sheet material by a second die unit;
- and
- moving the first die unit and the second die unit relative to each other in a thickness direction of the sheet material, thereby bringing the sheet material into contact a fulcrum portion and generating a tensile force to tear a weakened portion of the sheet material by the fulcrum portion,
- the method further comprising:
- generating, while an amount of movement of the second die unit relative to the first die unit is small, a tensile force on the weakened portion to tear a part near one end of the weakened portion by the first support surface of the fulcrum portion;
- and
- generating, as the amount of movement of the second die unit relative to the first die unit increases, a tensile force on the weakened portion to tear a part near an other end of the weakened portion by the second support surface of the fulcrum portion.
Dependencies are inferred from the claim text.