Laser Hardening of Rotational Workpieces Without Surface Gaps
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Solution Overview
Problem
Existing methods for surface hardening of large rotationally symmetrical workpieces, such as rolls and cones, face challenges in achieving homogeneous hardening due to the limited area of action of focused laser beams, leading to time-consuming processes and incomplete coverage of large surfaces.
Innovation Solution
A method involving a laser device that rotates the workpiece and moves along its longitudinal axis to maintain constant intensity of high-energy radiation, allowing for either intermittent or continuous coverage of the surface, ensuring homogeneous hardening by adjusting the displacement or speed of the laser to prevent gaps and optimize energy distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a focused laser beam is used for surface hardening, then the hardness penetration depth is improved, but the area of action is limited and hardening of large surfaces becomes time-consuming
Solution Approach 1:
The workpiece surface is divided into multiple annular zones that are hardened sequentially during rotation. The laser beam focuses on specific annular regions, creating segmented hardening zones that can be precisely controlled in terms of depth and width, while the rotational movement enables coverage of the entire surface area.
Solution Approach 2:
The hardening process transitions from a static linear scan to a rotational annular path, adding a rotational dimension to the laser-workpiece interaction. This enables the laser to cover the entire circumferential area of the workpiece surface while maintaining focused energy concentration, thereby increasing the effective hardening area without sacrificing penetration depth.
2Productivity
If the laser device is moved along the longitudinal axis only, then the area of action is limited, but the intensity of radiation remains constant
Solution Approach 1:
The patent combines two motion modes: rotational movement of the workpiece about its longitudinal axis and axial translation of the laser device along the same axis. This merging of rotational and translational motions allows the laser to cover both the circumferential and longitudinal extents of the workpiece surface, achieving complete coverage without gaps while maintaining constant radiation intensity through proper synchronization of the two motions.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enables quick, efficient, and homogeneous surface hardening of large areas, maintaining consistent hardness penetration and reducing the formation of traces or gaps, thereby extending the lifespan of tools like shape rolls and crusher cones.
Implementation Method 1
Martensitic transformation hardening by the action of concentrated high-energy laser radiation is known. In laser hardening, the outer layer of carbon-containing ferrous materials (C content >0.3%) is heated up so quickly that the cooling down takes place as self-quenching by the surrounding cold layers of material.
Implementation Method 2
the cooling down takes place as self-quenching by the surrounding cold layers of material
Data Source
AI summary
The invention relates to a surface-hardened, rotationally symmetrical workpiece, to a hardening method and to a hardening apparatus. The proposed hardening apparatus comprises a machine frame on which two coaxially arranged rotary bearings designed to support a rotationally symmetrical workpiece are arranged, at least one rotary bearing being operatively connected to a drive device to generate rotation of the workpiece; and at lease one laser apparatus for generating focussed, high-energy radiation is arranged on said rotary bearing, said laser apparatus being movable in the axial direction, and the radiation being directed toward the workpiece.