Multi-layer Sliding Member for Rack-and-Pinion Steering
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Solution Overview
Problem
Multilayered sliding members used in rack-and-pinion type steering apparatuses face challenges with wear resistance and load bearing capability due to the environmental concerns associated with using lead or lead alloys as fillers, which are difficult to replace effectively with alternative materials.
Innovation Solution
A multilayered sliding member comprising a steel backing plate with a porous metal sintered layer coated with a synthetic resin composition containing specific amounts of barium sulfate, magnesium silicate, phosphate, and titanium oxide, enhancing wear resistance and load bearing capabilities without using environmentally harmful substances like lead.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If lead or lead alloy is used as a filler in PTFE sliding members, then wear resistance and load bearing capability are improved, but environmental contamination and pollution occur
Solution Approach 1:
The invention changes the chemical composition parameters of the filler material, replacing lead-based compounds with a specific combination of barium sulfate (5-30 wt%), magnesium silicate (1-15 wt%), phosphate (1-25 wt%), and titanium oxide (0.5-3 wt%). This parameter change maintains the desired wear resistance and load bearing capability while eliminating environmental contamination issues associated with lead.
Solution Approach 2:
The invention uses a composite filler system combining multiple inorganic materials (barium sulfate, magnesium silicate, phosphate, and titanium oxide) instead of a single lead-based filler. This composite approach synergistically provides wear resistance, load bearing capability, and environmental friendliness, resolving the contradiction between performance and environmental harm.
2Strength
If lead or lead alloy is used as a filler in PTFE sliding members, then load bearing capability is improved, but environmental pollution occurs
Solution Approach 1:
The invention modifies the filler composition parameters by eliminating lead and lead alloys entirely, replacing them with a specific formulation of barium sulfate (5-30 wt%), magnesium silicate (1-15 wt%), phosphate (1-25 wt%), and titanium oxide (0.5-3 wt%). This parameter change achieves the required load bearing capability without generating environmental pollution.
Solution Approach 2:
The invention employs a composite inorganic filler system that combines barium sulfate, magnesium silicate, phosphate, and titanium oxide in specific proportions. This composite material provides the necessary load bearing capability while being environmentally benign, thus resolving the contradiction between strength and environmental pollution.
3Object-affected harmful factors
If alternative fillers are used to replace lead, then environmental friendliness is improved, but wear resistance and load bearing capability deteriorate
Solution Approach 1:
The invention uses a composite filler system combining barium sulfate (5-30 wt%), magnesium silicate (1-15 wt%), phosphate (1-25 wt%), and titanium oxide (0.5-3 wt%) that synergistically provides both environmental friendliness and superior wear resistance. This composite approach overcomes the limitation of single alternative fillers that sacrifice performance for environmental benefits.
Solution Approach 2:
The invention optimizes the weight percentages of each filler component within specific ranges to achieve the desired balance between environmental friendliness and wear resistance. By carefully controlling these compositional parameters, the invention maintains high reliability while being environmentally benign.
4Object-affected harmful factors
If alternative fillers are used to replace lead, then environmental safety is improved, but load bearing capability deteriorates
Solution Approach 1:
The invention employs a composite inorganic filler system where barium sulfate (5-30 wt%), magnesium silicate (1-15 wt%), phosphate (1-25 wt%), and titanium oxide (0.5-3 wt%) work synergistically to provide both environmental safety and high load bearing capability, overcoming the deficiency of single alternative fillers.
Solution Approach 2:
The invention adjusts the compositional parameters of the filler materials within specific weight percentage ranges to optimize load bearing capability while maintaining environmental safety. This parameter optimization ensures that the alternative filler system meets the demanding load requirements without compromising environmental benefits.
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 solution provides improved wear resistance and load bearing capabilities, enabling smooth sliding of the rack bar in a rack-and-pinion type steering apparatus, outperforming traditional multilayered sliding members containing lead while being environmentally friendly.
Implementation Method 1
a porous metal sintered layer formed integrally on a surface of the backing plate
Implementation Method 2
Polytetrafluoroethylene resins (hereafter abbreviated as PTFE) which are used for the multilayered sliding members described in Patent Documents 1 to 3, are used extensively for sliding members such as bearings since they excel in self-lubricating properties
Data Source
Figure 1~3
Figure 4~6
AI summary
A multilayered sliding member 51 includes: a backing plate 52 formed of a steel plate; a porous metal sintered layer 53 formed integrally on the surface of the backing plate 52; and a sliding layer 54 constituted of a synthetic resin composition filling pores of, and coating the surface of, the porous metal sintered layer 53, the synthetic resin composition being composed of 5 to 30% by weight of a barium sulfate, 1 to 15% by weight of a magnesium silicate, 1 to 25% by weight of a phosphate, 0.5 to 3% by weight of a titanium oxide, and the balance of a polytetrafluoroethylene resin.