Tri-metal bearing supports tri-directional ten tonne load

Citation

(1998), "Tri-metal bearing supports tri-directional ten tonne load", Aircraft Engineering and Aerospace Technology, Vol. 70 No. 3. https://doi.org/10.1108/aeat.1998.12770cab.042

Tri-metal bearing supports tri-directional ten tonne load

Tri-metal bearing supports tri-directional ten tonne load

Keywords Bearings, Consarc, Criptic-Arvis

An unusual bearing has been supplied by Leicester-based Criptic-Arvis, manufacturer of plummer blocks, bearing housings and plain bearings, to Consarc Engineering, a leading designer and manufacturer of vacuum furnaces.

The single bearing has to support a three metre long, ten tonne electrode which is melted into a crucible in a Consarc VAR furnace. An electric arc is struck between the vertical electrode and the crucible and has to be accurately maintained in both strength and position to ensure a quality melt.

An unusual bearing has just been supplied by Criptic-Arvis to Consarc Engineering

This means that the electrode has to be moved in both x and y horizontal planes to keep it central within the diameter of the crucible while a ram provides movement in the z-axis, pushing the electrode though the bearing as melting proceeds. All movements are electronically controlled through servo motors to ensure the required positioning and melt rate.

The control system also has to contend with eccentricity in the electrode and non-linear weight reduction as the melt progresses. The crucible is water cooled and if the arc moves off centre it could burn through the crucible wall.

The bearing is a large self-aligning plain type comprising rings of different materials. The tri-metal housing features a steel ring, chrome plated and polished and an SAE660 leaded bronze ring. These are separated by an adjustable brass shim stack of 21 leaves each 0.07mm thick.

Bore is 430mm diameter and 140mm wide, while the housing is 564mm diameter. It is lubricated with dry-slide to control the drag on the electrode. Criptic-Arvis has the capability to machine such housings from blocks up to a metre cube and up to two tonnes in weight. This enables in-house production of the male and female spherical components of these large self-aligning bearings.

Consarc Engineering designs and manufactures vacuum furnaces for a wide range of metal production including brazing, melting, heat treatment and processing. It employs some 70 people at Bellshill, Scotland, and sells worldwide into the aerospace industry where high temperature materials are processed.

A typical electrode could consist of a high yielding material as used in aircraft undercarriage housings. Other furnaces from the company are used in the solution heat treatment of single crystal turbine blades, brazing of metals such as Inconel and diffusion bonding of titanium turbine fan blades.

Managing director Eric Remic says the company is a subsidiary of USA-based Consarc Corporation and has a blue-chip base of customers throughout the UK, Europe, Asia and the Far East. Besides a range of standard furnaces, Consarc Engineering manufactures custom designs for specialised applications from full production units to laboratory scale products.

Criptic-Arvis manufactures its own product range of plummer blocks, bearing housings and plain bearings and offers stock items as well as many special items. Established in 1981, the company's service complements the high volume bearing manufacturers by producing small batches at competitive prices and offering a customised service. In 1991, it was one of the first UK bearing companies to attain BS 5750 registration and is now certified to ISO 9002.

It uses CAD in design and also offers a digitising service for reverse engineering. Sales director John Wright says this service is proving increasingly popular as companies often cannot find documentation or drawings of damaged or worn components. When machines move from company to company, and companies fail or merge, the transfer of documentation is often partial, or even overlooked. Digitising provides a fast, precise computer model of a component plus documentation for CNC machining and for customer reference.

This service is ideal where cast-iron plummer blocks crack or break, claim the company. Criptic-Arvis can offer a mild steel replacement, either flame cut or CNC machined, which saves the tooling and mould costs of manufacturing another casting. It also takes less time.

Details from Criptic-Arvis Ltd, Croft Grange Works, 16 Bridge Park Road, Thurmaston, Leicester LE4 8BL, UK. Tel: +44 (0)116 260 9700; Fax: +44 (0) 116 264 0147.