Plate bending apparatus

Claim 1

An apparatus for bending a plate, comprising: a bending press having a die forming a part of bearing points for supporting a plate to be bent, a movable bottom of said die disposed below said bearing points and movable relative thereto to limit the penetration of a bent edge of said plate to establish a predetermined depth of bending and thereby determining a bending angle for said edge of said plate, and a bending punch disposed above said die and including: an upper section displaceable by a hydraulic press, a lower section directly below said upper section having a bending edge bearing upon said plate between said points, an electrical pressure gauge having a piezoelectric quartz crystal interposed between said sections, and guide means between said sections for laterally supporting and guiding said upper section on said lower section whereby a plate-bending force applied to said plate by said punch is registered by said electrical pressure gauge; a computer connected to said electrical pressure gauge for comparing bending forces registered by said gauge with predetermined forces required for a specific plate material to attain a predetermined bending angle as said punch penetrates into said die; and a control unit connected to said computer and to said movable bottom for displacing said movable bottom to limit the depth of which said plate is bent by said punch to a value determined by said computer to obtain said predetermined bending angle for said plate and said material.

Claim 2

An apparatus for bending a plate, comprising: a bending press having a die forming a part of bearing points for supporting a plate to be bent, a movable bottom of said die disposed below said bearing points and movable relative thereto to limit the penetration of a bent edge of said plate to establish a predetermined depth of bending and thereby determining a bending angle for said edge of said plate, and a bending punch disposed above said die and including: an upper section displaceable by a hydraulic press, a lower section directly below said upper section having a bending edge bearing upon said plate between said points, an electrical pressure gauge having a piezoelectric quartz crystal interposed between said sections, and guide means between said sections for laterally supporting and guiding said upper section on said lower section whereby a plate-bending force applied to said plate by said punch is registered by said electrical pressure gauge; a computer connected to said electrical pressure gauge for comparing bending forces registered by said gauge with predetermined forces required for a specific plate material to attain a predetermined bending angle as said punch penetrates into said die; and a control unit connected to said computer and to said movable bottom for displacing said movable bottom to limit the depth of which said plate is bent by said punch to a value determined by said computer to obtain said predetermined bending angle for said plate and said material.