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EP-4737051-A1 - METHOD FOR LASER CUTTING AT LEAST TWO PARTS OUT OF A SHEET METAL AND CREATING A RESIDUAL SHEET PORTION FROM WHICH FURTHER PARTS CAN BE CUT

EP4737051A1EP 4737051 A1EP4737051 A1EP 4737051A1EP-4737051-A1

Abstract

Method for laser cutting a sheet metal (1) extending in a cutting plane (1a) and delimited by a peripheral edge (1b), comprising the step of: a) cutting at least two parts (100) out of the sheet metal (1) by moving a laser beam in the cutting plane (1a) along a closed cutting path (P) which begins and ends at a lead in/out point (100b) and follows a contour (100a) of the respective part (100); b) cutting the sheet metal (1) by moving the laser beam in the cutting plane (1a) along a cutting line (L) to divide the sheet metal (1) into: - a scrap sheet portion (3) which contains the lead in/out points (100b), and - a residual sheet portion (2), separate from the scrap portion (3), out of which further parts can be cut, wherein the cutting line (L) is positioned in the cutting plane (1a) so that it has: - at least a first segment (L1) extending between the contours (100a) of two of the at least two parts (100), and - two second segments (L2) associated to a respective part (100) and extending between the peripheral edge (1b) of the sheet metal (1) and the contour (100a) of the respective part (100).

Inventors

  • MENDOZA, ROBERTO
  • Zingg, Markus

Assignees

  • Bystronic Laser AG

Dates

Publication Date
20260506
Application Date
20241031

Claims (13)

  1. Method for laser cutting a sheet metal (1) extending in a cutting plane (1a) and delimited by a peripheral edge (1b), the method comprising the step of: a) cutting at least two parts (100) out of the sheet metal (1), the at least two parts (100) being delimited by a respective contour (100a) and being spaced apart in the cutting plane (1a), each part (100) being cut out of the sheet metal (1) by moving a laser beam in the cutting plane (1a) along a closed cutting path (P) which begins and ends at a lead in/out point (100b) and follows the contour (100a) of the respective part (100); b) cutting the sheet metal (1) by moving the laser beam in the cutting plane (1a) along a cutting line (L) to divide the sheet metal (1) into: - a scrap sheet portion (3) which contains the lead in/out points (100b), and - a residual sheet portion (2), separate from the scrap portion (3), out of which further parts can be cut, characterized in that the cutting line (L) is positioned in the cutting plane (1a) so that it has: - at least a first segment (L1) extending between the contours (100a) of two of the at least two parts (100), and - two second segments (L2), each second segment (L2) being associated to a respective part (100) and extending between the peripheral edge (1b) of the sheet metal (1) and the contour (100a) of the respective part (100).
  2. Method according to claim 1, wherein: - the first segment (L1) connects the cutting paths (P) associated with two of the at least two parts (100), - each second segment (L2) connects the peripheral edge (1b) of the sheet metal (1) to the cutting path (P) associated with the respective part (100).
  3. Method according to claim 1 or 2, wherein the first segment (L1) is connected to at least one of the two second segments (L2) by a connecting section (C) of the cutting path (P).
  4. Method according to any of the previous claims, wherein: - the cutting line (L) has a total length given by the sum of the lengths of the first segment (L1) and the second segments (L2), - the method comprising a cutting line positioning step c) before the cutting step b), wherein the position of the cutting line (L) is defined by minimizing the total length of the cutting line (L).
  5. Method according to claim 4, wherein the cutting line positioning step c) comprises the sub-steps of: c1) identifying a bundle of segments (B1, B2) for each first and second segments (L1, L2) to be defined, c2) computing the length of each segment of each bundle of segments (B1, B2), c3) selecting the first and the second segments (L1, L2) from the respective bundle of segments (B1, B2) such that the total length of the cutting line (L) is the smallest.
  6. Method according to any of the previous claims, wherein the first segment (L1) extends linearly along a first direction (D1-D1) and the second segments (L2) extend linearly along a respective second direction (D2-D2), the first direction (D1-D1) and the second direction (D2-D2) being parallel.
  7. Method according to claim 6, wherein the first direction (D1-D1) and the second direction (D2-D2) are coincident.
  8. Method according to any of the previous claims, comprising a set-up step d) before the cutting step b), wherein: - in the set-up step d) the position of a piercing point (O) in the cutting plane (1a) is computed for each first and second segments (L1, L2), the piercing points (O) being arranged on the scrap sheet portion (3) outside of the respective first or second segments (L1, L2), - in the cutting step b) the laser beam is moved in the cutting plane (1a) starting from the piercing points (O) to cut the respective first or second segment (L1, L2) of the cutting line (L).
  9. Method according to claim 8, wherein: - each piercing point (O) is connected to the associated first or second segment (L1, L2) by a respective bridging section (T) directed transversely to the associated first or second segments (L1, L2), - in the cutting step b), for each first and second segments (L1, L2), the laser beam is moved in the cutting plane (1a) starting from the respective piercing point (O) along the respective bridging section (T) and then along the respective first or second segment (L1, L2) at first in a first direction of movement (V 1) toward one of the parts (100) then in an opposite second direction of movement (V2) toward the other part (100) or the peripheral edge (1b) of the sheet metal (1).
  10. Method according to claim 8 or 9, wherein: - the piercing point (O) associated with the first segment (L1) is in a first middle region (M1) between the respective two parts (100), - the piercing points (O) associated with the second segments (L2) are in a second middle region (M2) between the respective part (100) and the peripheral edge (1b) of the sheet metal (1).
  11. Method according to the any of previous claims, wherein the first segment (L1) and the second segments (L2) of the cutting line (L) have at least one end portion (EP) which is spaced from the contour (100a) of the respective part (100) by a safety distance (D).
  12. Method according to any of the previous claims, wherein: - at least one of the two parts (100) is partitioned in a first part portion (1001) and a second part portion (1002) separate from the first part portion (1001), the first part portion (1001) and the second part portion (1002) being defined by the contour (100a) of the respective part (100) and a partitioning segment (100c), the partitioning segment (100c) separating the first part (1001) from the second part (1002), - the cutting path (P) of each part (100) which is partitioned into the first part portion (1001) and the second part portion (1002) comprising the partitioning segment (100c).
  13. Computer program product comprising instructions which, when the program is executed by a computer unit of a laser cutting machine, cause the laser cutting machine to carry out the method according to any of the previous claims.

Description

Technical field The present invention relates to a method for laser cutting at least two parts out of a sheet metal and creating a residual sheet portion from which further parts can be cut. The present invention also relates to a computer program which, when executed by a computer unit of a laser cutting machine, causes a laser cutting machine to carry out the above-mentioned laser cutting method State of the art Laser cutting is a well-known technology that uses a laser beam to vaporize materials, resulting in a cut edge. This laser cutting technology has been combined with computer numerical control in CNC machines to automate the cutting operations of parts from metal sheets. In order to reduce production waste and thus the environmental impact, laser cutting methods configured to separate the processed sheet metal into a scrap sheet portion and a residual sheet portion have been developed. In detail, with reference to Figure 1, these known laser cutting methods create the residual sheet portion by making an additional straight residual cut C, apart from at least one previously cut part W, which divides the processed sheet S into the residual sheet and scrap portions S 1, S2. The residual cut C is placed as close as possible to the cut workpiece(s)/part(s), maintaining a minimum safety distance so as not to damage it (them). Although these known laser cutting methods allow a portion of the cut sheet (i.e. residual sheet portion) to be recovered for re-use, they are far from optimal as they create extra skeleton for scrap metal between the part(s) and the residual cut. Moreover, these known laser cutting methods require a lot of time and energy to make the residual cut that separates the residual sheet portion from the scrap sheet portion. Scope of the invention In this context, the technical task underlying the present invention is to propose a method for laser cutting a sheet which overcomes the aforementioned drawbacks of the known art. In particular, it is an object of the present invention to provide a method for laser cutting a sheet metal which allows to increase the recovered residual sheet portion and reduces the time and energy required. In other words, it is an object of the present invention to provide a laser cutting method which, compared to the known ones, uses less time, less energy and generates less scrap out of the same cutting plan for the same sheet. Summary of the invention The method for laser cutting a sheet metal of the present invention, after cutting at least two parts out of the sheet metal by moving a laser beam along a respective closed cutting path which begins and ends at a lead in/out point and follows the part contour, comprises the step of dividing the sheet metal into a scrap sheet portion which contains the lead in/out points and a residual sheet portion form which further parts can be cut. In detail, the sheet metal is divided into scrap and residual sheet portions by moving the laser beam along a cutting line positioned to have at least one first segment extending between the contours of two parts and two second segments extending between the peripheral edge of the sheet metal and the contour of a respective part. Such positioning of the cutting line saves cutting work (i.e. cutting time and cutting energy) by taking advantage of the cuts made to cut the parts from the sheet. Specifically, such positioning of the cutting line makes it possible to separate the sheet metal into scrap and residual sheet portions by using (part of) the cuts previously made along the cutting paths to connect the first and second segments. Moreover, such positioning of the cutting line increases the area of the residual sheet by eliminating the aforementioned extra skeleton for scrap metal that remains between the parts and the residual cut when the known methods are used. It is therefore evident that the method according to the present invention uses less time, less energy and generates less scrap out of the same cutting plan for the same sheet metal as compared to the known methods. According to one embodiment, the first segment connects the cutting paths associated with two parts and each second segment connects the peripheral edge of the sheet metal to the cutting path associated with the respective part. Such first and second segments make it easier to separate the scrap sheet portion from the residual sheet portion. According to one embodiment, before cutting the sheet metal along the cutting line, the method comprises a cutting line positioning step wherein the position of the cutting line is defined by minimizing its total length (i.e. the sum of the lengths of the first and second segments). Advantageously, the cutting line positioning step permits the determination of the optimum cutting line position which minimizes the cutting time and energy. According to one embodiment, the cutting line positioning step comprises the sub-steps of: identifying a bundle of segments for each fi