The design of a hydrostatic lubrication arrangement for the horizontal and transverse slides of a no. 3 archdale vertical milling machine

The Department of Production and Industrial Administration of The College of Aeronautics has made a detailed analysis into the performance of numerically controlled machine tools, and this shows that when these machines are operating under light cutting loads, the total envelope tolerance is about 0.003 ins. Further investigation into the source of the errors showed that about 80 per cent of this error was due to mechanical mechanisms in the machine tool. The electronic equipment operated inside a total band of 0.0004 ins. over small distances, and 0.0006 ins. over 10 inches. This situation appeared to justify a comprehensive survey into the methods which may be used to improve the mechanical performance of these machines. After due consideration had been given to a number of possible alternatives, it was decided to fit hydrostatic lubrication to the slides, nut and screw arrangement, and the thrust bearings used on the X and Y axes of an existing No. 3 Archdale Milling Machine. The Z axis was not included in the redesign, because analysis showed that a new head casting would have been necessary. It was thought that this additional expense was not justified and that the data obtained from an examination of the performance given by the X and Y axes would show whether the system could be used with advantage in the design of new machines. The paper gives details of the calculations used to establish the dimensions of the new features fitted to the machine to satisfy the target performance conditions which appeared to be possible and are given in the introduction. The authors would like to express their appreciation to James Archdale and Co. for making a machine available for this investigation, to the Staveley Research Department, and in particular to Mr. Graham, Mr. Harris, Mr. Huntley) M r. Cummings and Mr. Hayward

The stability of honeycomb sandwich panels in shear

This abstract presents the results obtained by theoretical and experimental methods for the buckling of honeycomb sandwich panels in shear. Details of the specimens analysed are shown in Figs. 1 and 2. The test rig is shown in Fig.3, and the accuracy with which uniform shear was obtained is illustrated in Fig.4. The experimental results are given in Fig. 5, where buckling and failing shear stresses are plotted against the ratio panel width "b" to panel thickness "d". No consistent effect attributable to the difference in face thickness for the panel series A and B is shown by these results. Comparison between theory and experiment is shown in Figs. 6 and 7. The results for buckling agree substantially with plate theory for the case of simply supported edges. Corrections of plate theory to allow for shear flexibility of the filling can virtually be neglected. Discrepancies between theory and experiment for b/d <80 are probably due to an insufficiently accurate allowance for plasticity

Thermal stresses in thin cylindrical shells, stiffened by plane bulkheads, for arbitrary temperature distributions

A study has been made of the thermal stresses reulting near the joint of a cylinder and internal bulkhead due to arbitrary temperature distributions in the configuration and to the consequent compatability forces and moments at the joint. The method is general enough to permit the inclusion of joint thermal resistance but certain limitations are placed on the form of the axial temperature distribution in the cylinder. An approximate method to determine the transient temperatures for completely general heating programmes is also proposed

The influence of turbulence on the structure and propagation of enclosed flames

Although it has long been established that burning rates can be appreciably increased by turbulence, the actual extent of this increase and the precise mechanism involved are still far from clear. The object of the present research was to examine the effects of turbulence on burning velocity and on the physical structure of the flame surface under flow conditions similar to those experienced in turbojet afterburner systems

Push-pull fatigue properties of wires in an iridium - 5% tungsten alloy

Introduction This memorandum reports a series of tests to determine the fatigue properties of an iridium - 5% tungsten alloy at 600°c and 700°C. A previous memorandum, Memo. Mat. 61, reports the fatigue properties at room temperature of the same alloy

Human factors problems in the design of vibration isolation systems: a contribution to the evaluation problem of passenger car suspension systems

1.0 Introduction In Appendix 1 of this report general procedures for the design and evaluation of vibration isolation, systems. are reviewed. It is shown that in general., a: vibration isolation system is adequate only when it enables a human operator to meet the objectives of some system by performing a task well enough and for long enough. If the vibration intrudes too far upon the operator's performance and endurance the system of which he is a part will not meet its objectives. There still remain examples today where inadequate vibration isolators limit the performance of a system. The agricultural tractor is one of these. It is not uncommon to see a tractor driver supplementing the tractor tyre spring by using his own vibration isolators - his legs

Drum atomisation studies

Studies have been made into the behaviour of rotating drums as a means of atomisation and fuel injection for gas turbine engines. Radial holes in the wall of the drum discharge liquid continuously, forming jets which atomise on contact with the surrounding air. The effects of rotational speed, drum diameter, liquid flow rate and hole proportions have been investigated using water and kerosine. The flow and atomisation characteristics have been established and are discussed in terms of application to the gas turbine. It is apparent that savings in complexity, weight and hence cost of fuel systems may be achieved with drum atomisers, but these may be offset to some extent by the increased costs of full scale annular combustion chamber development

'Short' S.C.7 turbo-skyvan Mk.2 Economics of the crop-spraying role

Short Eros. and Harland Ltd. have carried out a brief preliminary study of the Turbo-Skyvan for crop-spraying and have derived payload data and operating costs on a provisional basis. Further studies have been carried out by the College to assess the Turbo-Skyvan on the basis of economic comparison with typical available aircraft operating on agricultural work and this report deals with the detail of these comparisons. Conclusions are that under European small-field conditions 3 , the Skyvan only becomes competitive when advantage is taken of its versatility to provide a single operator with a number of roles, one of which would be cropspraying, thereby increasing utilisation to more realistic figures (1500 and 2000 hrs/yr. have been investigated, in addition to the average 'crop-spraying only' utilisation of 400 hrsiyr). Under Afro-Asian operating conditions, with larger fields and greater areas ', the above comments are still substantially true but, when the higher utaisations are considered, the Skyvan is cheaper to operate and has a higher application capacity than its assumed competitors

Farnham rolls investigation

The object of this experiment was to investigate the possibility of obtaining pre-setting data for the 1 Farnham Rolls'. The experiment was carried out by applying certain deflections and measuring the resulting radii of curvature. Thus curves of curvature against deflection were produced for different sheet widths, and from these curves attempts to produce a conical frustum with prescribed radii were made. The results obtained can not be applied to conical parts, but this test served to indicate that it is possible to obtain pre-setting data for various applications

Test report no. PLBO/11 comparison of PERPRO grade WK8/T0354 against grade CLV when machining Meehanite

Tools of grade 14K8/T0354 and CLV were tested at 300 f.p.m. cutting speed, 0.10 in. depth of cut and 0.010 in/rev. feed to 0.030 in. flankwear. The two bars of Meehanite used for the tests gave different results but in each case the performance of CLV was slightly better than that of WK8/T0354; this difference was more pronounced with the less easy to machine material