Thin-Walled Array Machining with In-Situ Freezing Clamping
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Solution Overview
Problem
Current machining methods for integrated thin-walled array structures face challenges in achieving high-performance clamping and machining efficiency due to weak rigidity, leading to low precision and surface integrity, with existing fixtures either being inflexible, costly, or prone to error accumulation and thermal stress.
Innovation Solution
An in-situ freezing machining method utilizing a system comprising a freezing device, auxiliary device, and refrigeration system to provide reliable support and thermal control through liquid nitrogen refrigeration, allowing for efficient clamping and machining by freezing water within the structure to match the workpiece surface and suppress thermal interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional fixtures (bespoke, box-joint, conformable, modular, or adsorption) are used for clamping thin-walled array structures, then clamping can be achieved, but machining precision and surface integrity deteriorate due to weak rigidity, clamping stress, or error accumulation
Solution Approach 1:
The patent changes the physical state of the clamping medium from solid (conventional fixtures) to liquid (water) that freezes during machining. This parameter change allows the clamping medium to transition from a rigid structure that causes stress to a fluid that adapts to the workpiece surface, then freezes to provide stable clamping without the drawbacks of conventional fixtures
Solution Approach 2:
The patent utilizes the phase transition of water from liquid to solid (freezing) during the machining process. The water is injected in liquid state to fill gaps and adapt to the workpiece surface, then freezes to provide rigid clamping support, and can be melted and removed easily after machining. This phase transition resolves the contradiction by providing both adaptability and rigidity at different stages
2Productivity
If bespoke fixtures are used for thin-walled parts, then machining efficiency is high, but flexibility is poor, cost is high, and technological cycle is long due to customization requirements
Solution Approach 1:
The water-based clamping system is self-adapting and requires no pre-customization. The liquid water automatically fills the gaps between the workpiece and fixture surface, conforming to any geometry without requiring bespoke design. This eliminates the need for customization while maintaining high machining efficiency
Solution Approach 2:
The water-based freezing clamping system serves multiple functions: it acts as a clamping medium, a cooling agent, and a support structure. This universal approach replaces multiple specialized fixtures with a single versatile system that can adapt to different workpiece geometries
3Adaptability or versatility
If conformable fixtures with lattice layout are used to match surface contour, then clamping adaptability is improved, but surface scratches and clamping stress occur reducing surface quality
Solution Approach 1:
The patent introduces water as an intermediary substance between the fixture surface and the workpiece. This intermediary allows the fixture to conform to the workpiece surface without direct rigid contact, preventing surface scratches. The water fills all gaps and contours, providing adaptability while protecting the workpiece surface
4Adaptability or versatility
If modular fixtures are used for clamping, then flexibility is high and standardization is achieved, but manufacture cost is extremely high, installation and adjustment time is long, and clamping precision deteriorates due to error accumulation
Solution Approach 1:
The patent replaces the complex mechanical modular fixture system with a fluid-based clamping system. Instead of using multiple mechanical components that accumulate errors, the liquid water provides continuous, error-free contact with the workpiece surface, freezing to provide precise clamping without mechanical error accumulation
5Ease of operation
If adsorption fixtures using air pressure are used for clamping, then contactless clamping is achieved, but surface wear, air leakage and other phenomena occur reducing clamping performance
Solution Approach 1:
The patent changes the state of the clamping medium from gas (air pressure) to liquid (water). The liquid water provides more stable and reliable clamping force compared to compressed air, eliminating air leakage issues. The water then freezes to provide even more reliable clamping performance while maintaining ease of operation
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 method ensures stable clamping and machining by leveraging the rigidity and low-temperature properties of ice, reducing machining deformation and thermal stress, thereby improving precision and surface quality while avoiding fixture installation errors and thermal issues.
Implementation Method 1
water filling and freezing are carried out in a cup array groove formed by the edge material for cup array and in the cup array
Implementation Method 2
refrigeration system mainly comprises a liquid nitrogen tank, a nozzle and refrigeration equipment
Data Source
AI summary
The present invention proposes an in-situ freezing machining method for an integrated thin-walled array structure. In the method, the area among cups is cut off first; then, the outer walls of a cup array are machined; and finally, water filling and freezing are carried out, and in-situ freezing machining of the inner walls of the cup array is carried out. Then, hoisting and turning over are carried out, and the area among cavities is cut off; then, the outer walls of a cavity array are machined; and finally, water filling and freezing are carried out, and in-situ freezing machining of the inner walls of the cavity array is carried out. The method realizes in-situ freezing clamping of workpieces, avoids error accumulation caused by repeated installation of a fixture, and can refrigerate efficiently, suppress ambient and cutting thermal interference, and ensure the stability of freezing fixture.