Case Study - HPB4³ - Major Machine Elements
The finished design has to be able to meet all three conflicting requirements of the cost, quality and time triangle. The specification has already been discussed but cost has to be controlled if the machine is to be offered competitively against other horizontal boring machines. The demand for machining large spindle housings continues to be high; this is the key driver in a challenging project schedule; the machine has to be delivered for installation in under a year from the start of the design process.
Structure
The machine base is made conventionally from cast iron but it is unconventionally split at the centre of the tee. The split would ordinarily be considered a weakness, but techniques developed by Cranfield Precision using solid, large area, compressed epoxy bonded interfaces have already been shown to be successful. The long machine beds on the Cinetic Landis LT3 crank grinder have been made in jointed sections without degrading the straightness performance of the long traverse axis.
Bed and Bridge Casting Design Lowest Mode Shapes
The site where the machine is to be installed cannot be excavated deep enough for the inclusion of a supporting concrete slab. This means that the machine base has to be self stiff and preferably, in operation supported only by three kinematic feet. A full FEA analysis has been carried on the individual machine castings to ensure that the bed has sufficient stiffness without having an excessive cross-section. The design target was to make the first mode no less than twice the maximum frequency that could be excited by rotation of the spindle. The iterative design approach using FEA has achieved 47 Hz which is only slightly short of the 50 Hz target with the spindle running at its maximum of 1500 rpm.
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Cranfield Precision operates to ISO9001 quality standard and is accredited by Lloyds Quality Register.
A Division of Cinetic Landis Ltd.
Registered in England
Registration Number 05577045
Registered Office: Cross Hills, Keighley, West Yorkshire, BD20 7SD