Universal shot-peening machine developed

Citation

(2002), "Universal shot-peening machine developed", Anti-Corrosion Methods and Materials, Vol. 49 No. 4. https://doi.org/10.1108/acmm.2002.12849dab.003

Universal shot-peening machine developed

Universal shot-peening machine developedKeywords: Peening, Surface preparation, Fatigue

USF Vacu-Blast International, part of the USF Surface Preparation Group, reports that it has developed a self-contained, "universal" shot-peening machine (Plate 2), capable of processing an extensive range of fan blades, discs and shafts from most aero-engines in current service in both the civil and defence aviation sectors. The machine is said to improve the fatigue resistance of these critical parts, in line with aero-engine manufacturers' specifications, and can be used for both production and repair/overhaul applications.

Plate 2 The "universal" shot-peening machine developed by USF Vacu-Blast International for aero-engine components. The special "slot tool" can be clearly seen through the access door

According to USF the new peener incorporates a sophisticated process control system and has been designed primarily to process defined areas of aero-engine turbine blade "roots" and their associated turbine disc blade slots, which are subject to both wear and fretting fatigue during service. The machine can accept blades of up to 1,000mm long and 250mm wide and discs of up to 1,100mm diameter and 350mm wide, and can also be used to peen other parts measuring up to 1,100mm in diameter by 600mm wide.

The processing enclosure measures 2,500mm x 2,000mm x 1,850mm high, and features a two-axis manipulator with an array of up to six peening nozzles. Three or four axes nozzle manipulation can be incorporated, if required. The nozzles are universally adjustable and can be strategically positioned to provide total coverage of parts of differing sizes and shapes. The parts are located in custom-designed work fixtures on a powered precision indexing turntable, itself fitted to a roll-in/roll-out rack-and-pinion-driven work carriage, which is loaded outside the enclosure by electric hoist. A special feature of the machine is a "slot tool" designed to ensure the efficient peening of disc blade slots of up to 280mm long. This operates independently of the main peening nozzles.

The machine's "Vacutrol II" Windows-based control system governs all processing parameters – nozzle selection and tracking path, slot tool operation, peening pressure and duration, shot flow rate, shot size and air purge – and utilises individual programs, which relate to the particular part being processed. The programs are input initially on a simple teach basis via a state-of-the-art man-machine interface (MMI), and are then recalled automatically when required either by typing in a part number or scanning a bar-code.

The machine can use different sizes of steel shot, according to the aero-engine manufacturer's specification, and incorporates in-cycle shot size and shape classification to ensure that only high quality media is returned to the peening nozzles through the integral continuously cycling generator-reclaimer "power-pack". Spent shot is recovered from the processing enclosure via a Vacu-Blast Waffle Floor pneumatic recovery system. This is incorporated into the base of the machine and conveys spent media pneumatically back to the power-pack and thence to the classifier for recycling. Degraded shot, dust and debris are directed to a free-standing dust collector. The recovery system has been specially designed to comply with the recent Rolls-Royce requirement for handling "S550" grade steel shot, in addition to the more universally used smaller sizes of shot-peening media.

Other features claimed of the new peener include high-efficiency "active" acoustic insulation to reduce operating noise levels, a "fast dump" media discharge valve to speed up shot size changes, and an improved specification "Magnavalve" unit to control shot flow rates to within ± 1 per cent of the specified rate.

For further information contact: USF Vacu-Blast International. Tel: +44 (0)1753 526511; Fax: +44 (0)1753 538093; E-mail: info@vacu-blast.co.uk; Web site: www.surfacepreparation.com