Ball Joint Aspherical Surface Injection Molding
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Solution Overview
Problem
The conventional manufacturing process for ball joints is complex and reduces productivity due to separate processing and assembly of components, which can lead to quality issues and limited torque performance when using ball studs with only spherical surfaces.
Innovation Solution
A ball joint design where a ball stud with a spherical head portion is integrated with a cap and socket, allowing the ball seat to be formed by injection molding, creating a sealed space and controlling torque through aspherical surfaces, thereby simplifying the manufacturing process and improving productivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the ball seat is manufactured separately and then assembled into the socket using complex assembly processes such as caulking, then the ball joint can be manufactured with conventional methods, but the productivity is lowered
Solution Approach 1:
The ball seat and socket are merged into a single integrated component manufactured through injection molding. The ball seat is formed as an integral part of the socket body, eliminating the need for separate manufacturing and assembly processes. This combining approach resolves the contradiction by simultaneously improving ease of manufacture (simpler process) and productivity (fewer assembly steps).
Solution Approach 2:
The socket is designed to perform multiple functions: it serves as both the structural housing and the ball seat support structure. The injection-molded socket integrates the ball seat formation function directly into its structure, allowing a single component to fulfill multiple roles that previously required separate parts and assembly operations.
2Ease of manufacture
If a ball stud with only a spherical surface is used for injection molding of the ball seat, then the manufacturing process can be simplified, but excessive torque is generated during rotation due to contact throughout the spherical surface
Solution Approach 1:
The spherical surface of the ball stud is modified by introducing an asymmetric aspherical portion that creates a localized contact area rather than uniform contact throughout the sphere. This asymmetric feature reduces the contact area between the ball seat and ball stud, thereby reducing friction and torque during rotation while maintaining the injection molding processability.
Solution Approach 2:
Instead of modifying the entire spherical surface uniformly, the invention applies a localized aspherical portion at a specific location on the ball stud. This local modification creates the desired reduced contact area effect only where needed, preserving the overall spherical geometry for manufacturing purposes while improving rotational characteristics.
3Manufacturing precision
If machining is performed on the spherical head portion to create a spherical surface, then the ball stud can be formed, but a protruding portion with a vertex is generated that interferes with the ball seat inner side surface
Solution Approach 1:
The aspherical portion is designed with an asymmetric geometry that deliberately avoids creating a vertex or protruding portion at the center. By offsetting the contact area and using non-uniform curvature, the design eliminates the interference problem with the ball seat inner side surface while maintaining adequate spherical surface accuracy for proper rotation.
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 design simplifies the manufacturing process, reduces costs, and enhances productivity by allowing for the formation of a ball seat with controlled torque through injection molding, eliminating the need for separate processing and assembly steps.
Implementation Method 1
a ball seat forming process in which the ball seat is formed by injection molding
Data Source
Figure 1~2(b)
Figure 3~4
Figure 5(a)~5(d)
AI summary
The purpose of the present invention is to provide a ball joint and a method for manufacturing the same, the method injection-molding a ball sheet using a ball stud having a spherical head portion, which has a non-spherical surface formed thereon, thereby simplifying the manufacturing process and improving productivity. In order to implement the purpose, a ball joint according to the present invention comprises: a ball stud (100) provided with a spherical head portion (110); a ball sheet (200) surrounding the outer peripheral surface of the spherical head portion (110) and allowing the ball stud (100) to play within an operating angle range; a cap (300) covering the spherical head portion (110) to form a sealed space between the cap (300) and the outer peripheral surface of the spherical head portion (110); and a socket (400) having an inner space, into which the spherical head portion (110), the ball sheet (200), and the cap (300) are inserted.