CoA. Memos: Manufacturing and Production (1963-1965)
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Item Open Access Hydraulic test rig(College of Aeronautics, 1964-08) Healey, M.Hydraulic Test Rig The rig comprises a grinding wheel head spindle driven by a motor and carrying an inertia load made up of detachable steel discs. On the opposite end of• the shaft to the motor is mounted a radial diffraction grating and a d.c. tachogenerator (see Fig. 1). Three motors are currently available, all with there own mounting brackets for easy changing: a) Vickers-Sperry, 6 axial pistons motor type MF-3906-30. b) Boulton Paul; 9 radial pistons with shaped cam track. c) Hartmann Rol-vane H.T.10 (Telehoist). Two types of spool valve are available: a) Dowty Moog, Series 22 b) Pegasus type 120. A manifold block is available to make the two Moog valves interchangeable. The Bolton Paul and Telehoist motors both have double ended shaft so that a tachometer can be mounted direct onto the motor. The tacho used in a Servo tech. (5 rads/sec./volt). The other tacho (mounted on the test rig) is an Evershed-Vignoles (7.9 rads/sec./volt). The Evershed is about 50% less noisy … [cont].Item Open Access An autocode programme to determine the flatness of a surface table using the least square mean plane criteria(College of Aeronautics, 1964-06) Scarr, A. J.Introduction The calculations involved in determining the flatness of a surface table from measurements made with instruments such as a block level or auto collimator can be lengthy, particularly where a large number of ordinates are taken. A solution to this problem is presented in this note in the form of an Autocode programme which will cater for up to 100 ordinates. The datum from which the variations in the flatness of the surface table are determined is the least squares mean plane. This may be defined as being that plane which makes the sum of the squares of the errors relative to it a minimum … [cont.].Item Open Access Machine tool laboratory: appendix A to progress report no. 2 on the investigation into grinding of nickel chrome alloy EPK31 produced by Henry Wiggins(College of Aeronautics, 19) Purcell, J.Introduction The work on the comparative tests of the effectiveness of coolants has continued. A wide range of soluble type coolants and straight oil coolants have been evaluated. The results of these tests are presented in a similar manner to that used in Progress Report Nos. 1 and 2, as Appendix A to Progress Report No. 2. From communications and inquiries in reference to the progress reports it may be that the clarity of the results could be improved to this end, more detailed attention to this is here included. Explanation of test results sheet headings. The Test Numbers, Wheel Type (specification Coolant, are all self explanatory. Grinding conditions This has been fully included in the progress reports, it is as follows: Table speed constant at 65 feet per minute Depth of cut constant at 0.001 ins. Gross feed constant at 0.042 ins. per table stroke Grinding wheel diameter maximum 7 ins. minimum 63/4 ins. Grinding wheel width 0.75 ins. constant. The grinding wheel specification and coolant are the variables, other conditions will be varied when initial testing is completed. The surface area ground. This heading means the area of surface ground under the standard conditions. per redress of the grinding wheel. All tests which achieve 75% of the previous test are repeated twice more. All products which achieve good results will be retested, and full calculations will be made. Full details and copies of results of any test are available on request. Surface finish The surface finish produced at each test is measured on the Taylor Hobson Talisurf. CLA is recorded, no trace record is made. This will be done when the most efficient products are retested. Where necessary brief remarks on a performance are included. These will be expanded and presented in greater detail when the final tests are made.Item Open Access An annotated bibliography of presentation of information in aircraft cockpits(College of Aeronautics, 1965-08) Fox, J. G.; Andrew, I. D. C.; Ferguson, I.INTRODUCTION In the preparation of, this bibliography only data which has been published after 1940 has been considered. The choice of this 'cut-off' point seemed, reasonable on two counts: it begins a period when cockpit displays become more varied and steadily become more complex so that the pilot's normal capacities increasingly become a limiting factor in the efficiency of the system: and it was in the early 'forties' that man's capacities first began to be related explicitly to equipment design. It would however have been presumptious to consider that no work before 1940 had any relevance; that some current principles could not be supported or rejected on the basis of pre-war research or practice. But it is unlikely that the pursuit of earlier work would have added anything to the information given by Nickles (1958) in A. History of Aircraft Cockpit Instrumentation1221:19LE. This admirable review is concerned primarily in showing how each instrument evolved and its purpose, how information was displayed in the cockpit and the mechanical principles employed. But it also considers the empirical solution to implicit ergonomic problems in this area, tracing the manner in which instruments were combined, simplified and arranged for better presentation. In some measure it warns against the presumption of ignoring early data for it points out that the 'recently' evolved principle of grouping instruments in horizontal or vertical arrays to ease the visual task of the pilot was suggested by Doolittle in his 'fog flying' experiments in 1929 … [cont.].Item Open Access The relevance of the mechanics of metal cutting to machinability(College of Aeronautics, 1965-08) Enahoro, H. E.; Welsh, M. J. M.INTRODUCTION The process of metal cutting is a subject of great importance to the makers and users of machine tools. Extensive research has gone into the subject but has still left most of the phenomena unexplained. Tool life is the main interest and before any real improvement in this factor can be made, the basic metallurgical factors governing the interaction between tool and workpiece must be better understood. Such improvement can be effected through control of the wear process since both tool and workpiece are metallic and machining is a process of metal flow which is associated with a serious wear problem. The absence of exact knowledge has however hampered empirical and mathematical approaches to the problem. Basically all machining operations are considered as either oblique or orthogonal cutting, the former requiring three dimensions to specify the geometry of the cutting part of the tool and the latter two. The basic metal cutting process to be considered is that which is common, in one form or another, to all metal cutting operations using a tool, that of the wedge-shaped tool in fig. 1 (a-j) (1). Analyses of cutting have been mainly concentrated on the relatively simple case of orthogonal or two-dimensional cutting. Here the tool is so set that its cutting edge is perpendicular to the direction of relative motion between tool and workpiece and generates a plane parallel to the original work surface. In doing this the tool removes a layer of material termed the chip. One of the major objectives of metal cutting theory is the determination of machining forces, chip geometry, tool life, energy consumption and surface finish from a knowledge of the physical properties of the workpiece and tool material and the cutting conditions alone. If this could be achieved, lengthy chip measurements, delicate dynamometry, tedious and costly tool life tests and surface finish measurements might be dispensed with.Item Open Access Large scale metrology(College of Aeronautics, 19) Scarr, A. J.INTRODUCTION It has been recognised in industry that the measurement of large components to high orders of accuracy presents a particularly difficult problem. This fact has been emphasised by a survey carried out by the N.P.L. (Ref. 1) in which a number of engineering firms in Great Britain were asked to declare the size of several prepared test pieces ranging in diameter from 15 inches to 80 inches. In general terms the result of this investigation showed that, under industrial conditions using conventional equipment, it was not possible V declare the size of large components to an accuracy of better than - 30 parts in a million under workshop conditions and - 15 parts in a million under inspection conditions. The survey also showed that above 20 inches the accuracy of determination of internal diameters was somewhat higher than for external diameters. The purpose of this paper is to indicate the main problems associated with measuring large sizes and to describe the experimental work undertaken at the College of Aeronautics in the design and testing of a new type of stick micrometer for internal diameters and micrometer frame for external diameters.Item Open Access Flow along tool-chip interface in orthogonal metal cutting(College of Aeronautics, 1965-07) Enahoro, H. E.; Oxley, P. L. B.In recent papers it has been suggested that over part of the toolchip contact zone the chip does not slide but sticks to the tool, chip flow taking place by shear within the body of the chip. Sticking contact is inconsistent with steady state cutting and in this paper a slip-line field model of chip flow is presented which does not include sticking contact and which is consistent with the relevant experimental observations.Item Open Access A systems approach to the design of procedures necessary for the organisation of student training flights(College of Aeronautics, 1964-08) College of Aeronautics, (Cranfield)The project was designed to familiarise the group with the use of system design techniques. The objective was to synthesis a system which would be suitable for providing training flights for students at The College of Aeronautics, Cranfield.Item Open Access A preliminary evaluation of a new control-knob design for electronic equipment(College of Aeronautics, 1964-08) Andrew, I. D. C.; Ferguson, I.; Talbot, R. J.Two experiments were carried out using five subjects to compare performance using standard and flush fitting rotary controls for electronic equipment. It vas found that the flush knob could be rotated more quickly through several revolutions, but a given setting accuracy was achieved less quickly using this flush knob. Some of the more general advantages and disadvantages of the flush knob are outlined. It should be noted that the primary objective of this study was to provide the participants with some experience in carrying out Human Factors studies and the time allowed was not such as to permit a comprehensive evaluation of the new knob design.Item Open Access Preliminary report on the analysis of the stresses in a die-bolster combination(College of Aeronautics, 1964-08) Oxley, P. L. B.; Welsh, M. J. M.An analysis is presented of the stresses in a carbide die-steel bolster combination. Results from a computer treatment of this analysis are given in tabular and graphical form. Suggestions are made as to the choice of interface diameters, and a nomogram is drawn enabling the maximum allowable interference to be selected.Item Open Access An interface design for a shock-tube system(College of Aeronautics, 1964-08) Beevis, D.; Leamon, T. B.; Lovesey, E. J.; Neale, J. G.; Strank, R. H. D.A linear display of lights and a mimic diagram arrangement of switches are suggested for the proposed high pressure shock tube control panel to enable the operator to follow a safe and reliable operating procedure.Item Open Access Horizontal band-saw(College of Aeronautics, 1964-05) Foot, R. M.; Boardman, G. E. T.; Dailey, B. R.; Baller, E. G. A.; Noble, C. F.The effect of various parameters on the performance of the band saw when cutting mild steel-with a 10 t.p.i. raker-set blade were established over a limited range. These are discussed fully in the ‘conclusions'. With this limited survey it was not found possible to establish the optimum conditions of operation.Item Open Access Estimating the charge size in explosive forming of sheet metal(College of Aeronautics, 1964-05) Noble, C. F.A method is given for estimating the charge size for the explosive forming of sheet metal components. The method is applied to a number of relatively simple shapes and good agreement is shown with experimental results.Item Open Access Test report no. PLBO/13: VTn curves for tools of grade SIP, RD107 and RD110 when machining EN9(College of Aeronautics, 1964-08) College of Aeronautics, (Cranfield)Summary Tools of SIP, RD107 and RD110 were tested at 300, 420 and 600 fpm cutting speed with .10 in depth of cut and .010 in/rev feed on EN9 to .030 in flankwear in order to find the constants in the expression VTn = C for the three grades. The values of ‘n’ were found to be .51, .53 and .46 and the values of C to be 4550, 4720 and 3620 for SIP, RD107 and RD110 respectively. It was found that at 600 fpm the crater wear of SIP was about a third of the wear of the other two grades.Item Open Access A new approach to the mechanics of metal cutting(College of Aeronautics, 1964-09) Oxley, P. L. B.Introduction A number of equations have been derived for predicting the shear angle (0 in Fig. 1) in orthogonal metal cutting. The best known of these is due to Merchant (1) who by assuming that the value of shear angle would be such as to give a minimum expenditure of work obtained the relation … [cont.].Item Open Access The application of the numerical method of evaluating the efficiency of grinding wheels and coolants for grinding nickel chromium alloy to specification E.P.K.31 (Henry Wiggin Ltd.) also the evaluation of surface residual stresses induced into the material by grinding: progress report no. 2(College of Aeronautics, 1963-12) Purcell, J.SUMMARY The material is presenting phenomena which though met and recognised previously the significance to the grinding process was on these previous occasions not critical. With this material, instead of a wheel life variation of 0.5% maximum there can be 3096 to 40% reduction in expected wheel life. A detailed explanation of this element of wheel face life will be included in the fine_ report when repeatable test results to substantiate the parley will be available. The test on soluble type coolants have not as yet been as successful as one would have hoped and it is intended to ask the supplier if an improvement can be made from the knowledge gained by the test here reported. The workpiece in all cases where soluble coolants were used remained cool, but with the very limited number of oil coolants some temperature rise in the workpiece is experienced. This temperature rise is not very critical if the workpiece is of sufficient surface area to allow cooling to take place more rapidly. The test piece used in the laboratory is 2.5 ins x 6 ins. long, and is now 0.5 ins. thick (originally 1.0 ins). The calculation is made and included for wheel specification Carborundum 5A 46/54 0.8 V.50 using Fletcher Miller Product M7/63 This is the first result which has given a performance life long enough to make these calculations and is included to enable any firm who must use results immediately to make use of our work. While not wishing to depreciate this product or to appear over enthusiastic I shall be surprised if improved life is not achieved but this fuller calculation will allow further appreciation of the numerical methods we are using.Item Open Access An investigation into high precision control of the relative angular position of two shafts over a range of speeds and ratios(College of Aeronautics, 1964-05) Healey, M.SUMMARY The paper sets out to describe how a servo mechanism may be applied to generative gear grinding machines and an appropriate specification is drawn up. The system involves separate motor drives to the two shafts, the angular positions of which are monitored with radial diffraction gratings. One of the signals is frequency divided to achieve the speed ratio between the two shafts, the resultant similar frequency signals being phase compared, any difference producing an error signal thus completing the servo loop. Hydraulic motors are used as prime movers. The transfer functions of the loop are developed and compared with measured open loop results. It is clearly shown that with the components at present available the loop cannot be made stable. The specification of more appropriate hardware is discussed and future work outlined, but the conclusion is reached that this system cannot be used for its primary purpose on a generative gear grinding machine.Item Open Access Test report no. PLBO/7 evaluation of PERPRO tools grade RD 92 machining EN 9(College of Aeronautics, 1963-12) College of Aeronautics, (Cranfield)Four tips of RD 92 were tested at 600 fpm cutting speed, 0.010 in./rev. feed and 0.10 in. depth of cut to 0.030 in. flankwear. Two tips gave a tool life of 56 min., but with severe crater wear. The other two tips gave a shorter life - one failing after 30 min. cutting as a result of the breakdown of the crater lip.Item Open Access The synthesis of a production information system(College of Aeronautics, 1965-06) College of Aeronautics, (Cranfield)Summary This report outlines a proposed information flow system, capable of giving Management the information necessary to effectively control the Production Organisation of Barretts shoe factory in Northampton. The report specifies the functions of each member of the system and assigns responsibilities to these functions and defines the information required to perform them. The system was designed using the philosophy and techniques of Systems Design.Item Open Access Project P. 15(College of Aeronautics, 1964-07) Beavis, D.; Strank, R. H. D.; Leamon, T. B.Summary System synthesis and analysis procedures were used to arrive at various conclusions about separation of functions, allocation of functions and, interface designs in a power station.