Hydrostatic Profiled Rail Guide Cu/Sn Alloy Coating

Resolve Bottlenecks,
Find Innovative Solutions
Generate Solutions

Solution Overview

Problem

Existing hydrostatic profile rail guides face challenges in maintaining consistent performance and emergency running properties due to manufacturing-related contamination and surface inaccuracies in the Cu/Sn alloy coatings, which affect the hydrostatic support and sliding properties.

Innovation Solution

A method involving a Cu/Sn alloy coating with a secondary copper coating applied galvanically to the guide carriage, followed by grinding to ensure precise surface quality and thickness, providing excellent sliding properties and emergency running capabilities even when hydrostatic pressure is lost.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a Cu/Sn alloy coating is applied to the guide carriage, then good hydrostatic pocket surface properties are achieved, but manufacturing contamination and surface inaccuracies occur

Engineering Contradiction:
Improvehydrostatic support performanceVSAvoidsurface quality and layer thickness accuracy
Core Design Contradiction:
ReliabilityVSManufacturing precision

Solution Approach 1:

A copper undercoating is applied to the guide carriage before the Cu/Sn alloy coating. This preliminary copper layer serves as a foundation that improves adhesion and provides a more uniform base for the subsequent alloy coating, reducing surface inaccuracies and contamination effects

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The copper undercoating acts as an intermediary layer between the steel guide carriage and the Cu/Sn alloy coating. This intermediate layer facilitates better bonding and creates a more stable substrate, reducing the impact of manufacturing variations on the final surface quality

Inventive Principle:
Principle #24Intermediary (Mediator)

2Manufacturing precision

If the first coating is ground to remove surface inaccuracies, then surface quality is improved, but layer thickness is reduced

Engineering Contradiction:
Improvesurface qualityVSAvoidcoating layer thickness
Core Design Contradiction:
Manufacturing precisionVSQuantity of substance

Solution Approach 1:

The copper undercoating is applied in advance to establish a uniform base layer. This preliminary layer compensates for the thickness reduction that will occur during grinding of the Cu/Sn alloy coating, ensuring that sufficient functional thickness remains after surface finishing

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

A composite coating structure is created with a copper undercoating layer and a Cu/Sn alloy top layer. This composite structure combines the advantages of both materials: the copper provides excellent adhesion and uniformity, while the alloy provides the required hydrostatic surface properties, with the total thickness optimized to account for subsequent grinding

Inventive Principle:
Principle #40Composite materials

3Reliability

If hydrostatic pressure is lost, then the bearing gap cannot be maintained, but emergency running properties are needed

Engineering Contradiction:
Improveemergency running capabilityVSAvoidhydrostatic support duration
Core Design Contradiction:
ReliabilityVSDuration of action of moving object

Solution Approach 1:

The Cu/Sn alloy coating with specific tin content (10-14 wt%) is applied in advance to provide emergency running properties. This coating acts as a protective cushion that enables the guide carriage to continue moving along the guide rail even when hydrostatic pressure is lost and the bearing gap collapses

Inventive Principle:
Principle #11Beforehand cushioning (Prior cushioning)

Solution Approach 2:

The chemical composition of the coating is optimized by controlling the tin content within a specific range (10-14 wt%). This parameter change transforms the coating properties to provide both hydrostatic support during normal operation and excellent sliding properties for emergency running when pressure is lost

Inventive Principle:
Principle #35Parameter changes

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 ensures consistent hydrostatic support and improved emergency running properties by maintaining a constant bearing gap and providing excellent sliding properties on steel guide rails, despite potential production impurities and surface inaccuracies.

Implementation Method 1

The pocket surfaces formed on the guide carriage are provided with a first coating consisting of a Cu/Sn alloy. The first coating is galvanically applied with high precision with the required surface quality

Methodology Applied
Scientific EffectGalvanic deposition: Electrodeposition

Implementation Method 2

The first coating is then ground so that some of the layer thickness of the applied coating is removed. Surface and layer thickness inaccuracies caused by the galvanic application process are eliminated by grinding

Methodology Applied
Scientific EffectAbrasion: Abrasion

Implementation Method 3

The pocket surfaces of the guide carriage and the rail running surface of the guide rail delimit a hydraulic gap or bearing gap through which hydraulic fluid that is provided under pressure in the pressure pockets can flow out in order to hydrostatically support the guide carriage on the guide rail

Methodology Applied
Scientific EffectHydrostatic pressure: Pressure Gradient

Implementation Method 4

The first coating according to the invention is a tin-bronze which has excellent sliding properties on the lateral surface of the steel guide rail, which is often ground. Consequently, an emergency running property is guaranteed even if the hydrostatic pressure is lost

Methodology Applied
Scientific EffectLubrication: Lubrication

Data Source

PatentEP2992231B1Hydrostatic profiled rail guide
Publication Date: 2018.04.11 SCHAEFFLER TECHNOLOGIES AG & CO KG
  • EP2992231B1 patent drawingFigure 1~2
  • EP2992231B1 patent drawingFigure 3
  • EP2992231B1 patent drawingFigure 4

AI summary

The invention relates to a hydrostatic profiled rail guide, having a guide carriage (2) which is arranged on a guide trail (1) so as to be longitudinally slidable and is hydrostatically mounted on said guide rail, wherein the guide carriage has pressure pockets and pocket surfaces arranged around the pressure pockets, and wherein the guide rail on the faces thereof facing towards the pressure pockets has rail running surfaces (7) for hydrostatic mounting of the guide carriage on the guide rail, wherein the pocket surfaces formed on the guide carriage have a first coating that consists of a Cu/Sn alloy.