Bolt Head Knurling for Exposed Metal Plate Fixing
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Solution Overview
Problem
Conventional fixing structures for metal plates and bolts to synthetic resin members often result in resin covering the upper surface of the metal plate, reducing connection reliability and increasing component size due to insert molding of both edges with the resin.
Innovation Solution
A fixing structure featuring multiple ribs extending from the outer edge of the bolt's head portion towards its center, with a knurled circumferential surface, allowing the metal plate to be securely fixed without insert molding both edges with the resin, and preventing resin coverage of the upper surface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If both edges of the metal plate are formed together with the synthetic resin member by insert molding to be fixed to the synthetic resin member, then the metal plate is securely fixed to the synthetic resin member, but the upper surface of the metal plate is covered by resin which lowers connection reliability between the metal plate and the LA terminal
Solution Approach 1:
The invention divides the fixing function into two separate mechanisms: (1) the head portion of the bolt is fixed to the synthetic resin member through insert molding, and (2) the metal plate is fixed to the head portion through fixing portions (ribs) that penetrate into the metal plate. This segmentation allows the metal plate's upper surface to remain exposed while maintaining secure fixing.
Solution Approach 2:
The invention extracts the metal plate fixation function from the insert molding process itself. Instead of fixing the metal plate directly through insert molding of its edges, the fixation is achieved through separate fixing portions on the bolt's head portion that penetrate into the metal plate, allowing the upper surface to remain accessible.
2Stability of the object's composition
If both edges of the metal plate are formed together with the synthetic resin member by insert molding, then the metal plate is fixed to the synthetic resin member, but the metal plate needs to be larger than the dimension required to locate the LA terminal, leading to an increase in size of the electric components
Solution Approach 1:
The fixing mechanism is segmented into the bolt's head portion being molded with the resin, and separate fixing portions (ribs) that penetrate the metal plate. This allows the metal plate to be smaller since it only needs to accommodate the LA terminal and the fixing portions, not extended edges for molding.
Solution Approach 2:
The fixing portions extend in the thickness direction of the metal plate rather than requiring lateral extension of the metal plate edges. This dimensional change allows secure fixing without increasing the metal plate's planar dimensions, thus reducing overall component size.
3Strength
If the head portion of the bolt is fixed to the synthetic resin member through insert molding, then the bolt is securely fixed, but torque can be transmitted to the metal plate causing bolt separation
Solution Approach 1:
The circumferential surface of the head portion is given a locally different quality through knurling or grooves, creating high-friction zones that prevent torque transmission to the metal plate while maintaining secure fixing to the resin member through the insert-molded portions.
Solution Approach 2:
The knurled or grooved surface structure is pre-formed on the head portion before assembly, creating a permanent high-friction interface that proactively prevents torque transmission and bolt separation before the problem can occur during 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 approach enables a downsized connector with improved connection reliability by exposing the metal plate's upper surface, reducing component size, and enhancing positional accuracy during molding, while preventing torque transmission and bolt separation.
Implementation Method 1
both edges 252, 253 of a metal plate 205 and a head portion 203 of a bolt 201 formed together with a synthetic resin member 207 by insert molding
Implementation Method 2
the circumferential surface of the head portion is knurled
Data Source
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AI summary
A downsized fixing structure for fixing a metal plate and a bolt to a synthetic resin member which can prevent an upper surface of the metal plate from being covered by a resin, is provided. The fixing structure includes : a bus bar, i.e. the metal plate; the bolt having the head portion and the shank portion passed through a through hole provided at the bus bar; and a housing (9), i.e. the synthetic resin member, to which the bus bar and the bolt are fixed. Fixing portions projecting from a surface of the head portion of the bolt adjacent to the shank portion of the bolt are arranged to penetrate into the metal plate to be fixed thereto. A circumferential surface of the head portion of the bolt is knurled. The head portion is formed together with the housing by insert molding.