Self-lubricating hinge assembly made from composite material and operating under high dynamic loads

Abstract

This assembly includes a ball joint assembled in a casing, and receiving an axle capable of sliding and/or rotating therein. The ball joint is formed from the winding of a fabric of small thickness ranging between 20 μm and 150 μm and mixed with a resin comprising fillers. The fabric has the form of strips having a width ranging between 5 mm and 200 mm; the strips being crossed in several layers.

Claims

1. A self-lubricating joint assembly operating under high loads in dynamic state and comprising a ball joint assembled in a casing, said ball joint receiving an axle capable of sliding and/or rotating in the ball joint, wherein the ball joint includes a core comprising a winding of a fabric of thickness ranging between 20 μm and 150 μm mixed with a resin comprising fillers, said fabric having the form of strips having a width ranging between 5 mm and 200 mm, said strips being crossed at a crossing angle ranging between 10° and 90° in several layers by filament winding, and wherein both an inner periphery and an outer periphery of the core are coated with a self-lubricating material.

2. The assembly of claim 1, wherein the fabric thickness ranges between 20 μm and 130 μm.

3. The assembly of claim 1, wherein a crossing angle of the crossing strips ranges between 30° and 86°.

4. The assembly of claim 1, wherein the fabric comprises synthetic fabric.

5. The assembly of claim 1, wherein the resin comprises epoxy, ester vinyl, polyester, phenolic, or polyimide.

6. The assembly of claim 1, wherein the fillers comprise PTFE, MoS2, or graphite.

7. The assembly of claim 6, wherein the fillers amount to between 5 and 70% of the volume.

Description

BRIEF DESCRIPTION OF THE DRAWING FIGURES

(1) The invention is discussed hereafter in further detail by means of the accompanying drawings, among which:

(2) FIG. 1 is a longitudinal cross-section view of the joint assembly formed by a self-lubrication sphere or ball joint engaged in a self-lubricating cage and made of fabric deposited by crossing according to the features of the invention to obtain a better homogeneity.

(3) FIG. 2 is a view corresponding to FIG. 1 after an axle has been installed in the ball joint bore.

DETAILED DESCRIPTION

(4) As indicated, FIG. 1 shows a self-lubricating ball joint or joint sphere (1) engaged in a cage (2) or casing. The bore (1a) of the ball joint (1) is intended to receive an axle (3) able to rotatably slide therein.

(5) The bore of the ball joint and its periphery are coated with a self-lubricating material (4). The desired aim is to avoid any seizing effect.

(6) According to the invention, the self-lubricating ball joint (1) is made from the winding of a synthetic fabric of small thickness ranging between 20 μm and 150 μm and advantageously between 20 μm and 130 μm.

(7) The fabric, which appears in the form of strips, is mixed with a resin of epoxy, ester vinyl, polyester, phenolic, polyimide, or other type.

(8) The resin comprises fillers of PTFE, MoS2, graphite or other type by on the order of from 5 to 70% of the volume.

(9) The aim is to obtain a product which is homogeneous across its entire thickness.

(10) The fabric strips have a width ranging between 5 mm and 200 mm and are wound on a mandrel of determined diameter, according to the filament winding technique.

(11) The strips are wound and crossed in several layers, the crossing angle ranging between 10° and 90° and advantageously between 30° and 86°. For example, the winding appears in the form of 9 plies of 100 μm as opposed to a winding according to the state of the art in the form of 3 plies of 300 μm.

(12) It should be noted that the fabric intended to be mixed with the resin may be made of taffeta, satin, twill or a cloth without excluding other fiber textures.

(13) Reference should be made to the following tests in the case of a joint in the form of a self-lubricating composite ball joint, according to the features of the invention and according to the state of the art (bearing E1 and bearing E2).

(14) Protocol

(15) Nature of the axle: 16 NC 6 CT Ra: 0.4

(16) Bearing nature:

(17) Type of bearing: Ball joint Ø35×Ø55×25

(18) Motion: Alternated rotation over 90°

(19) Pressure calculated in projected area: 40 MPa

(20) Sliding speed: 6 mm/s

(21) Criterion for Stopping the Test

(22) Friction coefficient >0.25

(23) Wear >0.5 mm

(24) Number of cycles reached: 365,000 cycles

(25) TABLE-US-00001 Test results Bearing according Crossed winding to the invention: Width of the fabric strip: 30 mm, thickness 0.10 mm Wear = 0.35 mm F < 0.1 Number of cycles: 365,000 cycles Bearing E1: Winding at 90° Width of the fabric strip: 1,200 mm thickness 0.30 mm Wear = 0.5 mm F < 0.2 Number of cycles: 2,500 cycles Bearing E2: Winding at 90° Width of the fabric strip: 1,200 mm thickness 0.30 mm Wear > 0.5 mm F < 0.25 Number of cycles: 3,000 cycles

(26) The advantages well appear from the description, and the following should in particular be underlined and reminded: a better dynamic load behavior due to the crossing of the fabrics, a better static load behavior due to a better homogeneity of the material, the impossibility of a seizing between the ball joint and the axle.