Coil Spring Wire Linear Weakening for Clean Torsion Cutting
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Solution Overview
Problem
Existing methods for manufacturing coil springs, particularly those with large winding ratios, often result in burr formation and require high cutting forces, making it difficult to achieve clean cuts and potentially damaging the spring geometry and environment.
Innovation Solution
A method involving the creation of a predetermined breaking point on the wire surface through linear weakening, using techniques like notching or laser treatment, to reduce cutting forces and ensure a clean separation process, allowing for larger winding ratios and more efficient cutting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If torsion cutting is used to separate coil springs from wire, then burr-free cuts can be obtained, but it requires high cutting forces and is limited to small winding ratios
Solution Approach 1:
The patent applies preliminary action by creating a linear weakening (notch) on the wire surface at the intended cutting position before the actual torsion cutting process. This notch concentrates stress and initiates crack propagation, allowing the torsion cut to proceed with significantly reduced cutting forces while maintaining burr-free cut surfaces. The weakening is created by rolling or pressing a tool against the wire to produce a localized stress concentration point.
Solution Approach 2:
The patent applies local quality by creating a localized weakening only at the specific cutting position on the wire, rather than uniformly treating the entire wire. The linear weakening (notch) is confined to a small region at the intended separation point, concentrating the effect where needed while leaving the rest of the wire intact for spring formation. This localized modification enables reduced cutting forces without affecting the overall wire properties.
2Manufacturing precision
If torsion cutting is used for coil springs with large winding ratios, then clean cuts can be achieved, but the torsional force cannot be optimally concentrated at the cutting position
Solution Approach 1:
The patent applies preliminary action by pre-creating a linear weakening (notch) at the intended cutting position before torsion cutting. This notch serves as a stress concentrator that initiates crack propagation, allowing the torsion force to be effectively concentrated at the desired cutting position even for springs with large winding ratios. Without this preliminary weakening, the torsional force would be insufficient to concentrate properly at the cutting location for large winding ratio springs.
3Device complexity
If conventional cutting methods are used, then the process is simpler, but burrs are generated on the cut surface
Solution Approach 1:
The patent applies preliminary action by creating a linear weakening (notch) on the wire surface before the cutting process. This preliminary step modifies the wire's stress distribution so that subsequent cutting (whether torsion or other methods) produces burr-free surfaces. The notch concentrates stress at the cut line, ensuring clean separation without burr formation while adding only one preliminary operation to the process.
4Manufacturing precision
If high cutting forces are applied to achieve clean cuts, then burr-free surfaces can be obtained, but the spring geometry and environment are adversely affected
Solution Approach 1:
The patent applies preliminary action by creating a linear weakening (notch) at the cutting position before the actual cutting process. This preliminary modification allows subsequent cutting to proceed with significantly reduced forces, as the notch already concentrates stress and initiates crack propagation. This eliminates the need to apply high cutting forces that would otherwise damage spring geometry and increase environmental impact from noise and energy consumption.
Solution Approach 2:
The patent converts the potential harm of creating a notch (which might be seen as a defect) into a benefit by using the notch as a stress concentrator that enables clean, low-force cutting. The localized weakening that initially seems harmful actually facilitates the cutting process by concentrating stress where needed, reducing overall cutting forces, and preventing damage to spring geometry and environment.
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 burr-free cuts with reduced cutting forces, expanding the applicability of torsion cutting to higher winding ratios and improving the geometry and environmental impact of the spring manufacturing process.
Implementation Method 1
at least one laser beam can be radiated onto the wire surface to generate the weakening
Data Source
Figure 1~2
Figure 3A~3B
Figure 4A~4C
AI summary
The invention relates to a method for producing coil springs by spring winding by means of a numerically controlled spring winding machine, wherein a wire is fed by a feeding device of a forming device of the spring winding machine under the control of an NC control program and is formed into a coil spring by means of tools of the forming device, and a finished coil spring is then severed from the fed wire by means of a cutting device. Before the finished coil spring is severed, a linear weakening is produced in the region of the surface of the wire at least at two diametrically opposite segments of the wire circumference at a defined severing position along the wire. In one embodiment, two notching tools (152, 154) are used for this purpose, which superficially notch the wire from opposite sides without cutting through the wire. The finished coil spring is then severed from the fed wire at the severing position, e.g., by means of a torsion cut.