Hybrid Machine Tool for Thermal-Accurate Laser Cladding
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Solution Overview
Problem
Laser build-up welding in machine tools faces challenges with low dimensional accuracy and significant thermal expansion issues due to temperature changes, leading to unacceptable dimensional variations in workpieces.
Innovation Solution
A machine tool with a build-up welding head, temperature control device, and integrated sensor system for precise temperature and position measurement, allowing for automatic tool changing and storage, and a method for creating a production log to anticipate and manage thermal conditions during the manufacturing process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If laser cladding is used to manufacture workpieces, then material can be deposited to create complex geometries, but dimensional accuracy deteriorates with tolerances of 1 mm or more
Solution Approach 1:
The manufacturing process is divided into multiple passes with intermediate machining operations. The workpiece is built up in layers through laser cladding, then periodically machined to remove excess material and achieve precise dimensions. This segmentation allows the benefits of additive manufacturing while correcting dimensional inaccuracies at each stage.
Solution Approach 2:
The system performs preliminary laser cladding to build up material to near-final dimensions, then uses automated machining to achieve precise tolerances. The machining operations are planned in advance as integral parts of the manufacturing process, not as separate corrective steps.
2Productivity
If continuous laser cladding is performed without interruptions, then productivity increases, but workpiece temperature rises causing thermal expansion and dimensional inaccuracy
Solution Approach 1:
The manufacturing process alternates between laser cladding phases and machining phases in a periodic cycle. During cladding, material is deposited to build up the workpiece; during machining, the workpiece is cooled and dimensions are corrected. This periodic alternation prevents excessive temperature accumulation while maintaining overall productivity.
Solution Approach 2:
The system maintains continuous productive action by combining laser cladding and machining in an automated sequence without manual intervention. The transition between cladding and machining is seamless, with the workpiece remaining in the machine throughout the process, ensuring continuous useful work is performed while managing thermal effects.
3Ease of operation
If automated tool changing is implemented, then ease of operation improves, but device complexity increases
Solution Approach 1:
The tool holder is designed with universal compatibility to accommodate both laser cladding tools and machining tools through standardized interfaces (SK, HSK). The same tool holder and spindle system performs multiple functions - laser cladding, milling, drilling, turning - eliminating the need for separate dedicated equipment for each operation.
Solution Approach 2:
The system merges laser cladding functionality and machining functionality into a single integrated machine tool. The tool magazine, automatic tool changer, and spindle system handle both types of tools, combining what were previously separate processes into one unified system that reduces overall device complexity despite the added automation.
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
Enables precise and dimensionally accurate workpiece manufacturing by predicting and controlling thermal effects, reducing thermal expansion issues and improving manufacturing accuracy.
Implementation Method 1
laser cladding is primarily used as a manufacturing process for coating objects with desired finishes or for near-net-shape repair welding
Implementation Method 2
The material to be welded is liquid and typically has a temperature exceeding 1500 °C
Implementation Method 3
The coefficient of thermal expansion of iron is 10−5 /°C. A temperature gradient of, for example, 300°C between the manufacturing temperature (approximately above 300°C) and the operating temperature (approximately room temperature) leads to a dimensional change of 3 x 10−3 or 3‰
Implementation Method 4
the welded material does cool relatively quickly (in the case of iron/steel) to below red heat (below 500 °C), but relatively high workpiece temperatures are still reached
Data Source
Figure 1~2
Figure 3~4a
Figure 4b~5
AI summary
The invention relates to a machine tool (10) comprising a machine controller (19), a machine frame (11), a work table (13), a tool holder (14), preferably of a standardized design, multiple translational and/or rotational axes (12a, 12b) for adjusting the relative position of the work table (13) and the work holder (14), a tool magazine (16) for one or more material-removing, in particular machining tools (15), a tool-change mechanism for automatically transporting tools between the tool holder (14) and the tool magazine (16), a deposit-welding head (20) that can be inserted into the tool holder (14) and a storage device (25) for storing the deposit-welding head outside the tool holder (14).