Machine Tool Temperature Compensation for Inhomogeneous Workpieces
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Solution Overview
Problem
Existing machine tools struggle with processing workpieces that have temperature deviations from a predefined processing temperature, particularly those with inhomogeneous temperature distributions, leading to inaccuracies and long waiting times for tempering, and current compensation methods fail to account for local heat effects and material variations.
Innovation Solution
A machine tool equipped with temperature sensors, such as thermal imaging sensors, to determine actual temperature distributions and deformations, coupled with a control unit that calculates and compensates for these deviations by adjusting processing paths and dimensions in real-time, considering expansion coefficients and fixation influences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If workpieces are tempered to pre-defined normal temperature to eliminate temperature influence, then manufacturing precision is improved, but production time increases due to long waiting time for temperature equalization
Solution Approach 1:
The patent applies preliminary action by pre-calculating temperature-induced deformations using finite element analysis before machining begins. The system determines the temperature distribution and resulting deformations in advance, then compensates for these deformations by adjusting the tool path and cutting parameters before the actual machining operation, eliminating the need for time-consuming tempering processes.
Solution Approach 2:
The patent utilizes parameter changes by dynamically adjusting machining parameters (tool path coordinates, cutting speeds, feed rates) based on the measured temperature distribution and calculated deformations. The control system modifies the nominal tool path parameters to compensate for thermal expansions and contractions, allowing machining to proceed at the current temperature state rather than requiring temperature equalization.
2Measurement precision
If thermal imaging sensors are used to determine temperature distribution, then measurement precision is improved for inhomogeneous temperature fields, but device complexity increases
Solution Approach 1:
The patent replaces mechanical contact temperature measurement methods with thermal imaging sensors that use infrared radiation detection. This substitution allows non-contact, full-field temperature measurement across the workpiece surface, capturing inhomogeneous temperature distributions without the complexity of multiple point measurements or physical contact with the workpiece.
Solution Approach 2:
The patent creates a thermal image copy or map of the workpiece temperature distribution, which is then processed through finite element analysis to determine deformations. This copying approach allows the system to work with a digital representation of the temperature field rather than requiring direct physical measurement at every point, simplifying the overall measurement and compensation process.
3Device complexity
If conventional temperature compensation methods are used with single-point sensors, then device complexity is reduced, but manufacturing precision deteriorates due to homogeneous view assumption that ignores local heat effects
Solution Approach 1:
The patent segments the temperature measurement into multiple zones or regions across the workpiece surface using thermal imaging. Instead of treating the workpiece as a homogeneous entity with a single average temperature, the system divides the temperature field into discrete measurement points and zones, allowing local heat effects and inhomogeneous distributions to be captured and compensated for in each region independently.
Solution Approach 2:
The patent applies local quality by determining temperature-induced deformations specifically for each measurement point or zone rather than applying a uniform compensation across the entire workpiece. The finite element analysis calculates local deformations based on local temperature distributions, and the tool path compensation is adjusted locally to account for regional thermal expansions and contractions, improving precision for inhomogeneous temperature fields.
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 high-precision processing of workpieces with temperature deviations by dynamically adjusting processing paths, reducing waiting times and improving accuracy by accounting for actual temperature-induced deformations and material properties.
Implementation Method 1
at least one temperature sensor that is configured to determine one or more actual temperature values of the workpiece
Implementation Method 2
Deviations from this homogeneous normal temperature influence dimensions of the workpiece due to temperature-influence including local or overall deformations (e.g. expansions)
Data Source
Figure 1a~1b
Figure 2
Figure 3~5
AI summary
The invention pertains to a machine tool for processing a workpiece (2) having a temperature (52) that deviates from a pre-defined processing temperature (51), the machine tool comprising a base to position the workpiece on, at least one processing means for processing the workpiece (2), one or more actuators for moving the processing means relative to the base, a control unit for controlling the actuators, the control unit comprising a data storage for storing nominal data providing nominal dimensions of the workpiece at the pre-defined processing temperature, and at least one temperature sensor (5A, 5B) that is configured to determine one or more actual temperature values of the workpiece, wherein the at least one temperature sensor is configured to generate temperature data based on the determined actual temperature values and to provide the temperature data to the control unit, the control unit is configured to calculate actual dimensions of the workpiece based on the nominal dimensions and on the provided temperature data and to control the actuators to process the workpiece according to the calculated actual dimensions, wherein the machine tool comprises one or more fixations (19) for fixing a position and orientation of the workpiece on the base, the machine parameters comprise information about the fixations, the nominal data comprises one or more expansion coefficients of the workpiece, and the control unit is configured to calculate the actual dimensions of the workpiece also based on the expansion coefficients of the workpiece and on the information about the fixations.