Coil Spring Tapered End Turns Force Line Control
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Solution Overview
Problem
Controlling the force line of a vehicle suspension coil spring is challenging, even for skilled professionals, and existing methods are not suitable for production by hot forming coiling machines.
Innovation Solution
A vehicle suspension coil spring design featuring taper portions at the end turn portions, which control the force line by varying the wire thickness along the length, allowing for precise adjustment of the force line position and inclination, and can be produced using both hot and cold forming coiling machines.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the force line is controlled by devising the shape of the effective portion and spring seat, then the suspension function can be optimized, but the manufacturing complexity and difficulty increase significantly
Solution Approach 1:
The patent applies local quality by creating a taper portion only at the end turn portions of the coil spring, while the effective portion maintains a uniform cylindrical shape. This localized modification of wire thickness (reducing it gradually from the end turn portion toward the effective portion) enables force line control without complicating the overall spring design or manufacturing process
Solution Approach 2:
The patent changes the physical parameter of wire thickness in the end turn portions by introducing a taper portion with gradually varying thickness. This parameter change (from uniform thickness to tapered thickness) modifies the stress distribution and force line position, achieving better suspension performance while maintaining simple manufacturing
2Productivity
If a long wire is used for cold working to produce multiple coil springs, then productivity increases, but it becomes difficult to form the required plastic working portion at the wire end before coiling
Solution Approach 1:
The patent applies preliminary action by forming the taper portion (plastic working portion) at the end of the wire before the coiling process. This pre-formed taper portion serves as a guide and structural element that facilitates the coiling operation, particularly when using a long wire for cold working to produce multiple springs sequentially
3Shape
If hot working is used to form the coil spring, then it is suitable for producing coil springs with large wire diameter, but the wire must be heated to high temperature requiring precise temperature control
Solution Approach 1:
The patent changes the physical state parameter by heating the wire to austenitizing temperature during hot working, transforming the material properties to enable forming. The taper portion is formed during this hot working process when the material is more ductile, allowing complex end turn geometry without excessive force or risk of cracking
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
The coil spring effectively controls the force line, enhancing its suspension function and can be efficiently produced using hot coiling machines, enabling desired performance in vehicle suspension systems.
Implementation Method 1
a wire that is heated to a high temperature (for example, an austenitizing temperature of steel)
Implementation Method 2
an effective portion of a cylindrical shape between the lower end turn portion and the upper end turn portion
Data Source
Figure 1
Figure 2~3
Figure 4~5
AI summary
A coil spring (2) for a vehicle suspension according to one embodiment includes a lower end turn portion (20), an upper end turn portion (21), and a cylindrical effective portion (22) between the lower end turn portion (20) and the upper end turn portion (21). In at least one of the upper end turn portion (21) and the lower end turn portion (20), a taper portion (25)(26) having a taper length and a taper thickness for controlling a force line (FL) of the coil spring (2) is formed. The taper portion (25)(26) is formed such that the thickness is reduced in a tapered way from a thickness varying portion (25a)(26a) provided in the middle of the end turn portion (20)(21) toward a distal end of the wire (4) along its length. The thickness varying portion (25a)(26a) is arranged at a position close to the force line (FL).