Laser welding of steel with power modulation for hot-cracking prevention

US11045901B2 · kind B2 · utility

Assignee

• TRUMPF LASER- UND SYSTEMTECHNIK GMBH · DE

Inventors

• Nicolai Speker · Pleidelsheim, DE
• Marcel Schäfer · Ditzingen, DE
• Philipp Scheible · Mühlacker, DE
• Thomas Graf · Bern, CH
• Peter Stritt · Stuttgart, DE

Key dates

• Filing date: Sep 18, 2018
• Grant date: Jun 29, 2021
• Expiry date: Apr 16, 2039

Classification

• Technology area (CPC B): Performing Operations; Transporting
• CPC primary: B23K26/32
• WIPO field: Machine tools
• WIPO sector: Mechanical engineering

Abstract

A laser beam directed is moved relative to a workpiece to weld along a weld seam and form a weld pool in the area surrounding the laser beam. The weld pool has a characteristic oscillation frequency fco, and a laser power is modulated with a modulation frequency f and a modulation amplitude Π=1−Pmin/Pmax, where Pmin is minimal and Pmax is maximal laser power during a modulation period. For a normalized characteristic oscillation frequency Λco and a normalized modulation frequency Λ, Λ≥2.2*Λco, with Λ=f·df/ν, where ν is the feed rate of the laser beam, and df is diameter of a beam focal spot. Also, Λco=f,cotest·df,cotest/vcotest, where fcotest is a measured characteristic oscillation frequency, df,cotest the diameter of the beam focal spot, and vcotest is the feed rate of laser beam, all during a test measurement without modulation of the laser power.