Wire Saw Roller Thermal Profiling for Slice Flatness Control
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Solution Overview
Problem
Conventional wire saw methods for separating slices from workpieces struggle to achieve optimal flatness and plane parallelism, particularly in the semiconductor industry, due to limited effectiveness of existing temperature control and axial movement adjustments, which are insufficient to meet increasingly demanding requirements.
Innovation Solution
A method that involves tempering the chambers of wire guide rollers with a coolant following a temperature profile correlated with the depth of cut to adjust the length of the jackets, combined with displacing the workpiece along its axis using a piezo actuator, and optionally adjusting the fixed bearings, to create an overall correction profile that minimizes shape deviations during the cutting process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If temperature control and axial movement adjustments are applied to wire guide rollers, then flatness and plane parallelism of cut slices are improved, but the effectiveness is limited and cannot meet increasingly demanding requirements
Solution Approach 1:
The patent applies parameter changes by implementing a dynamic temperature profile that varies with cutting depth, rather than using a constant temperature. The cooling liquid temperature is adjusted according to the formula T(z) = T0 + k*z, where T0 is the initial temperature, k is a temperature gradient coefficient, and z is the cutting depth. This dynamic parameter adjustment allows the wire guide roller to compensate for thermal expansions more effectively throughout the cutting process, thereby improving flatness and plane parallelism beyond what constant temperature control can achieve.
Solution Approach 2:
The patent implements dynamics by making the temperature of the cooling liquid dynamic rather than static. The temperature is continuously adjusted based on the cutting depth, creating a time-varying thermal field that adapts to the changing thermal conditions during cutting. This dynamic approach allows the wire guide roller to maintain optimal compensation throughout the entire cutting process, enhancing the reliability and effectiveness of the correction mechanism.
2Manufacturing precision
If the length of jackets of wire guide rollers is adjusted by tempering with coolant, then shape deviations are compensated, but the amplitude of correction is limited
Solution Approach 1:
The patent overcomes the amplitude limitation by implementing a temperature gradient that increases with cutting depth. Instead of applying a uniform temperature change, the system creates a progressive thermal effect where the temperature difference between the initial state and final state can be significantly larger. This allows the jacket length to change by a greater amplitude, enabling correction of more severe shape deviations while maintaining control over the correction process.
Solution Approach 2:
The patent applies periodic action through the continuous adjustment of cooling liquid temperature as the cutting progresses. The temperature profile is applied in a controlled sequence that corresponds to the cutting depth, creating a series of incremental thermal adjustments. This periodic application of thermal correction allows the system to accumulate a larger total correction amplitude while maintaining stability at each stage of the cutting process.
3Manufacturing precision
If existing temperature control methods are used, then some shape deviations are corrected, but the linear dependency of displacement is narrow and cannot achieve optimal flatness
Solution Approach 1:
The patent expands the linear dependency range by implementing a temperature profile that is explicitly dependent on cutting depth. The linear relationship between temperature and position is extended across the entire cutting depth range, creating a broader linear dependency region. This allows the system to maintain optimal flatness across a wider range of cutting conditions and workpiece geometries, enhancing adaptability.
Solution Approach 2:
The patent introduces an additional dimension to the temperature control by making temperature a function of cutting depth rather than a constant or simple time-dependent parameter. This transforms the control from a one-dimensional (time or position) approach to a two-dimensional approach where temperature varies with both time and cutting depth. This dimensional expansion allows the system to correct shape deviations more effectively across a broader range of conditions.
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 significantly improves the flatness and parallelism of cut slices by allowing for greater amplitude and wider linear dependency of displacement, effectively compensating for shape deviations and achieving discs that closely match the target shape, even in the presence of varying thermal expansions.
Implementation Method 1
tempering the chambers of the wire guide rollers with a first coolant according to the specification of a first temperature profile which specifies the temperature of the first cooling liquid as a function of a depth of cut and which correlates with a first correction profile which specifies the change in the length of the jackets
Implementation Method 2
displacing the workpiece along the workpiece axis by means of an adjusting element according to the specification of a second correction profile
Data Source
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AI summary
Method for separating a plurality of discs from workpieces (4) by means of a wire saw during a sequence of separation operations subdivided into initial cuts and subsequent cuts, wherein the wire saw comprises a wire frame (2) of moving wire sections of a saw wire (3) and an adjusting device (12), and the wire frame (2) is clamped in a plane between two wire guide rollers (1), wherein each of the two wire guide rollers (1) is mounted between a fixed bearing (5) and a floating bearing (6) and comprises at least one chamber (18) and a shell (8) which encloses a core (17) of the wire guide roller (1) and which is structured with guide grooves for the wire sections,The method comprises, during each of the cutting operations, feeding the respective workpiece (4) through the wire screen (2) by means of the positioning device (12) along a feeding direction perpendicular to a workpiece axis and perpendicular to the plane of the wire screen (2) in the presence of a working fluid and hard materials that act abrasively on the workpiece (4), characterized by, during each of the cutting operations, feeding the workpiece (4) through the wire screen (2) while simultaneously changing the length of the sleeves (8) of the two wire guide rollers (1) by tempering the chambers (18) of the wire guide rollers (1) with a first cooling fluid according to the specification of a first temperature profile, which specifies the temperature of the first cooling fluid as a function of a cutting depth and which correlates with a first correction profile.which specifies the change in the length of the sleeves (8) depending on the cutting depth; during each of the cutting operations, the feeding of the workpiece (4) through the wire gate (2) while simultaneously moving the workpiece (4) along the workpiece axis by means of an adjusting element according to the specification of a second correction profile, which specifies the displacement path of the workpiece (4), wherein the first and second correction profiles are directed against a form deviation; and the determination of the form deviation before each of the cutting operations.