Patent ID: 6941848

Claim:
A method of producing a bar notch ( 3 ) in a side of a side member ( 1 ) and a cross member notch ( 4 ) on an end of a cross member ( 2 ) using an apparatus having a triangular knife head, a guide for slidably supporting said triangular knife head therewithin, said guide being movable in a horizontal direction, a table, a rest disposed on said table, a second guide disposed on said table, and a second guide member slidably disposed on said second guide and slidable in a direction crosswise to the rest, the method comprising the steps of: preliminarily shearing or punching said side member ( 1 ) at a first depth (d) from a side surface ( 1 ′) of said side member ( 1 ), preliminarily shearing or punching said cross member ( 2 ) at said first depth (d) from a side surface ( 2 ′) of said cross member ( 2 ), and secondarily shearing or punching said side member ( 1 ) at a second depth (D) from said side surface ( 1 ′) of said side member ( 1 ) to produce said bar notch ( 3 ) wherein said bar notch ( 3 ) includes a plane bottom ( 5 ), which is parallel with said side surface ( 1 ′) in the side member and two equally long, oblique sides ( 6 ), which have oppositely direct equal inclinations in relation to the bottom ( 5 ) having an angle of less than 90°, and secondarily shearing or punching said cross member ( 2 ) at said second depth (D) from said side surface ( 2 ′) of said side member ( 2 ) to produce said cross member notch ( 4 ), wherein the cross member notch has a plane end ( 7 ) in a cross member ( 2 ) and two inclined sides ( 8 ), wherein said first depth (d) of said preliminary shearing or punching of said side member ( 1 ) is less than but similarly oriented to said second depth (D) of said secondary shearing or punching of said side member ( 1 ), and wherein said first depth (d) of said preliminary shearing or punching of said cross member ( 2 ) is less than but similarly oriented to said second depth (D) of secondary shearing or punching of said cross member ( 2 ), whereby said side member can be joined with said cross member by the bar notch ( 3 ) fitting into said cross member notch ( 4 ).