Coil Spring Forming with Servo-Driven Roller Slip Prevention
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Solution Overview
Problem
In coil spring manufacturing, the rotating body fails to rotate if the frictional force between the wire rod and the rotating body's outer surface does not exceed the maximum static frictional force, leading to wire rod slipping and potential damage, especially when using wire rods with lower strength or smaller diameters, which can result in low-quality coil springs or difficulties in forming.
Innovation Solution
Adjusting the rotary drive source to set the circumferential speed of the rotating body's outer surface close to the feed speed of the wire rod, eliminating the need for the wire rod to withstand high frictional forces, thereby allowing precise coil spring formation with various wire rod strengths and sizes, including those with low strength or small diameters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the rotating body is configured to rotate in accordance with the movement of the wire rod through frictional force, then the frictional resistance is reduced and quality deterioration is suppressed, but the wire rod must have high strength to endure until the rotating body starts rotating
Solution Approach 1:
The rotating body is pre-driven by a drive source to rotate before the wire rod is fed. This preliminary rotation eliminates the need for the wire rod to generate sufficient frictional force to start the rotating body's motion, thereby removing the requirement for high wire rod strength while maintaining reliable coil spring formation
Solution Approach 2:
The friction-based mechanical coupling between the wire rod and rotating body is replaced by a direct drive mechanism. The drive source directly rotates the rotating body, substituting the frictional force transmission mechanism and eliminating the strength requirement on the wire rod
2Shape
If the wire rod is pressed against the rotating body outer circumferential surface to form coils, then coil shaping is achieved, but wire rod slipping occurs when frictional force is insufficient
Solution Approach 1:
The rotating body is pre-rotated by the drive source before wire rod contact. This ensures the rotating body maintains rotational motion without slipping, providing stable coil shaping while eliminating the reliability issue of slip prevention that would otherwise require high frictional force
3Reliability
If high frictional force is generated between the wire rod and rotating body, then the rotating body rotates reliably, but the wire rod requires excessive strength to withstand the frictional force
Solution Approach 1:
The friction-based force transmission system is replaced with a direct drive system. The drive source directly applies torque to rotate the rotating body, eliminating the need for high frictional force between the wire rod and rotating body while ensuring reliable rotation
Solution Approach 2:
The requirement for high wire rod strength to generate frictional force is extracted and removed from the system. The drive source independently provides the necessary rotational force, separating the rotation function from the wire rod's mechanical properties
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 prevents wire rod slipping and damage, enabling precise coil spring formation even with wire rods of lower strength or smaller diameters, and eliminates the need for excessive frictional force, ensuring high-quality coil springs can be manufactured without strength limitations.
Implementation Method 1
a frictional force is generated between an outer circumferential surface of the rotating body and the wire rod so as to rotate the rotating body around an axis of the rotating body
Data Source
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AI summary
A method of manufacturing a coil spring and a coil spring manufacturing apparatus (1) are provided that enable precise forming of a coil spring even when various kinds of wire rods are used as a wire rod (M). This is based on the premise that the wire material (M) being fed out is serially pressed against a rotating roller outer circumferential surface (5a) to form the wire rod (M) into a coil shape. Under this premise, as the wire rod (M) is fed out, a rotating roller (5) is rotationally driven by a rotary drive force of a servomotor (20) such that a portion pressed against the wire rod (M) on the rotating roller outer circumferential surface (5a) moves toward the advancing side of the wire rod (M).