Sliding Shaft Resin Coating to Prevent Vacuum Voids
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Solution Overview
Problem
The formation of vacuum voids in resin coating layers on sliding shafts used in vehicle steering devices is a challenge, particularly when using polyamide 610 as the base resin, which has high viscosity and low throwing power, leading to defects and strength degradation.
Innovation Solution
Incorporating an antistatic agent such as carbon black or metal oxide into the powder coating material to inhibit charging and agglomeration, allowing for the formation of a continuous resin coating layer without thick application, thereby preventing vacuum voids.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If polyamide 610 is used as the base resin to improve heat resistance, then heat resistance is improved, but the resin has high viscosity and low throwing power making it difficult to form a continuous coating layer
Solution Approach 1:
The patent changes the physical and chemical parameters of the powder coating material by incorporating antistatic agents (carbon black or metal oxide) to modify the electrical properties. This reduces electrostatic charge accumulation on the shaft surface, allowing the high-viscosity polyamide 610 resin to flow and form a continuous coating layer despite its poor throwing power.
Solution Approach 2:
The patent creates a composite powder coating material by combining polyamide 610 base resin with antistatic agents (carbon black or metal oxide). This composite structure maintains the heat resistance of polyamide 610 while adding electrical conductivity properties that prevent charge accumulation, enabling successful coating formation.
2Manufacturing precision
If the shaft is immersed repeatedly in powder coating material to increase coating thickness and achieve continuity, then coating continuity is improved, but vacuum voids are easily formed in the resin coating layer
Solution Approach 1:
The patent applies antistatic agents to the powder coating material before the coating process. This preliminary action prevents electrostatic charge accumulation that would otherwise cause powder agglomeration and uneven deposition, allowing a continuous coating to be formed in a single immersion without repeated dipping that would create voids.
Solution Approach 2:
By changing the electrical parameters of the coating system through antistatic agents, the patent modifies the deposition behavior of the powder. The reduced electrostatic charge allows for more uniform powder distribution and adhesion during a single immersion, forming a continuous layer without the need for multiple immersions that trap air voids.
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 use of antistatic agents like carbon black or metal oxide enables the formation of a continuous, void-free resin coating layer on sliding shafts, enhancing the strength and heat resistance of the coating, suitable for high-temperature environments like engine rooms.
Implementation Method 1
in a fluidized bed, the powder coating material is placed in a floating and fluidized state by blowing air or the like
Implementation Method 2
the powder coating material is deposited, and allowed to melt and flow, on the outer circumferential surface of the male shaft or the inner circumferential surface of the female shaft
Implementation Method 3
the resultant is cooled thereafter, resulting in forming a resin coating layer on the deposited surface
Implementation Method 4
Incorporating an antistatic agent such as carbon black or metal oxide into the powder coating material to inhibit charging and agglomeration
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
In a sliding shaft, an outer circumferential surface 21a of a male shaft 21 is coated with a resin coating layer 27 formed by a fluidized bed powder coating method using a powder coating material containing a base resin and at least either a carbon black or a metal oxide as an antistatic agent. A steering device includes this sliding shaft as an intermediate shaft transmitting steering force.