Method and apparatus for the production of bent sheet metal pieces

• US 6,065,323 A
• Filed: 05/26/1998
• Issued: 05/23/2000
• Est. Priority Date: 05/27/1997
• Status: Expired due to Term

• Current Assignee: AMADA COMPANY, LIMITED AND CREA S.R.L.
• Original Assignee: Amada Company Limited, CREA SRL (NMC Health Plc)
• Inventors: Prunotto, Gianpaolo, Arduino, Alberto
• Primary Examiner(s): Larson, Lowell A.
• Application Number:
  US09/084,016
• Time in Patent Office: 728 Days
• Field of Search: 72/383, 72/379.2
• US Class Current: 72/379.2
• CPC Class Codes: B21D 11/20 Bending sheet metal, not otherwise provided for
• CPC Class Codes: B21D 5/02 on press brakes without making use of clamping means

Abstract

A method and apparatus for the production of bent sheet metal pieces (12) is disclosed. In the method or apparatus, a cut (14) is made in a sheet of sheet metal (10) that defines the perimeter of piece (12) to be obtained. The cut (14) is interrupted at preselected points to form a series of microjoints (16) that keep the plan development of the piece (12) united with the stiffening frame (18) constituted by the remaining part of the metal sheet (10). At least one window (36, 38) is formed in the stiffening frame (18) in order to allow a pair of bending tools having a length greater than the length of the bend to form a bend (20, 22) on the piece (12) without interfering the stiffening frame (18) while the bend is being formed.

Claims

1. A method of forming a sheet metal piece in a metal sheet so that said sheet metal piece is joined by a micro joint to a stiffening frame of said metal sheet, the method comprising the steps of:

forming a window in an area of said stiffening frame adjacent to said sheet metal piece, the window extending from a position corresponding to the end of a flap of said sheet metal piece and along a side of said flap by a length that is at least equal to a width of said flap where a dimension of said window being based upon a dimension of a punch and die pair that are selected from a set of available punch and die pairs based upon a comparison of a length of the selected punch and die pair and the length of at least one bend line of said flap; and

bending said flap with said selected punch and die pair, wherein said selected punch and die pair rotates about a bending line.

2. The method of claim 1, wherein said micro joint is formed between an area of said sheet metal piece corresponding to a single face of said bent sheet-metal piece and an area of the stiffening frame facing that area of said sheet metal piece.

3. A metal sheet produced by the process recited in claim 1.

4. A method of manufacturing a sheet metal piece, said sheet metal piece having a bent flange, the method comprising the steps of:

(a) cutting a metal sheet to form said sheet metal piece so that said sheet metal piece is joined to a stiffening frame in said metal sheet by a micro joint;

(b) selecting one of a set of available tool pairs that has a length that is at least equal to the length of at least one bend line of said flange, each of said set of available tool pairs including a punch and a die that rotate about a bending line;

(c) forming a window in an area of said stiffening frame adjacent to said sheet metal piece and extending from a location corresponding to the end of a flap of said sheet metal piece and along a side of said flap by a length that is at least equal to a width of said flap and a dimension of said window being based upon a dimension of said selected tool pair;

(d) bending said sheet metal piece along a bending line using said selected tool pair; and

(e) separating said bent sheet metal piece from said stiffening frame.

5. The method of claim 4, wherein the steps of cutting and forming are combined.

6. The method of claim 5, wherein the length of the punch and die is greater than the length of the bending line.

7. The method of claim 6, wherein the window is rectangular, and a sum of the length of the bending line and the length of the window in the direction of the bending line is greater than the length of the punch and die.

8. The method of claim 6, further comprising forming a second window at the other end of said flap.

9. A method of producing at least one sheet metal piece, comprising the steps of:

comparing a length of at least one bend in said at least one sheet metal piece with the lengths of available tool pairs, each of said available tool pairs including a punch and a die that rotate about a bending line;

selecting one of a set of available tool pairs in a bending press that has a length that is at least equal to the length of the at least one bend;

making a cut in a metal sheet that follows a path that defines the perimeter of at least one sheet metal piece, the cut being interrupted at preselected points to form a series of micro joints that join said at least one sheet metal piece with a stiffening frame in said metal sheet, the cut also defining a window in said stiffening frame adjacent to a flap in said at least one sheet metal piece, a dimension of said window being based upon a dimension of said selected tool pair;

bending the flap of the at least one sheet metal piece with the selected one of a set of available tool pairs while the at least one sheet metal piece remains joined to said stiffening frame by said micro joints; and

separating the at least one sheet metal piece from the stiffening frame by one of the steps of cutting and breaking said micro joints.

10. The method of claim 9, wherein said window has a first dimension along said bend that forms a free space within said stiffening frame having a length that is one of equal to and greater than the length of the selected available tool pair.

11. The method of claim 9, wherein said window has a second dimension perpendicular from said bend that is one of equal to and greater than the width of said flap.

12. The method of claim 9, wherein said cut also defines another window on an opposite side of said flap.

13. The method of claim 12, wherein each of said windows is quadrangular.

14. An apparatus for a sheet metal piece having a bent flange from a metal sheet, comprising:

a cutting apparatus for cutting the metal sheet to form said sheet metal pieces in said metal sheet so that said sheet metal piece is joined to a stiffening frame of said metal sheet by a micro joint and for forming a window in an area of said stiffening frame adjacent said sheet metal piece and located on an extension line of a bending line of said sheet metal piece; and

a first control device that controls the cutting apparatus so that the cutting apparatus forms the window in the stiffening frame; and

a second control device that includes a bending tool selecting means that selects a bending tool from a plurality of bending tools and a window dimension calculating means that calculates a dimension of said window based upon a dimension of a selected bending tool, each of said bending tools including a punch and a die that rotate about a bending line.

15. The apparatus of claim 14, wherein the bending tool selecting means compares a length of one of a plurality of available bending tools with a length of said bending line and selects a bending tool that has a length that is greater than said bending line.

16. The apparatus of claim 14, wherein the second control device includes a bending tool data memory that stores the lengths of the available bending tools.

17. The apparatus of claim 14, wherein the second control device includes a sheet metal piece data memory that stores data regarding the shape and dimensions of said sheet metal piece.

18. The apparatus of claim 14, wherein the bending tool selecting means selects a bending tool such that a sum of the length of said bending line and the width of said window in the direction of said bending line is at least equal to the length of said selected bending tool and wherein the cutting apparatus cuts a window with a width in the direction perpendicular to the direction of the bending line that is greater than a length of a flange to be formed by a bending operation.

19. The apparatus of claim 14, wherein the cutting apparatus comprises a laser cutting machine.

20. The apparatus of claim 14, wherein the bending apparatus comprises a press brake.