bluuebunny/crossref_metadata_2025 huggingface dataset:
An Experimental Crank Press
Authors: Seed E. C. , Swift H. W.
Published: October 2007

An account is given of the technical problems which arose in the design of an experimental single-action, double-sided crank press of tie-rod construction which has been built for use in the deep-drawing researches carried out in the University of Sheffield.

This press was required to have a specified capacity of 20 tons during the second half of the down-stroke and 50 tons during the last inch of the down-stroke. To cover the drawing speeds of industrial practice, a variable speed of 5–60 strokes per min. and a variable stroke of 3–10 inches were specified, and to maintain a close control over the speed, the slowdown at any speed over the whole range was limited to 10 per cent. An air cushion and also an automatic means for stopping the press at top dead centre after each stroke and for interrupting the stroke at any prescribed point in order to obtain partially drawn pressings for examination and measurement were incorporated.

Speed variations are obtained through a transmission system consisting of a substantially fixed speed electric motor with a fixed gear to the flywheel, and a variable gearbox between the flywheel and the main gears of the press. It is shown that, from the functional points of view this is the most satisfactory system of power supply and transmission for a variable speed press.

Two safety devices are embodied in the press: a shear plate in the ram to protect the crankshaft and a shearing pin in the first reduction gear wheel to protect the gearing. The design of these devices is described in an Appendix.
Relations between Roll-force, Torque, and the Applied Tensions in Strip-rolling
Authors: Hill Rodney
Published: October 2007

Expressions are derived for the roll-force P, and torque G, in strip-rolling under tension, as functions of the pressure distribution on the rolls and of the radius of the deformed arc of contact. By consideration of various artificial distributions of pressure the ratio G/P is shown to depend only slightly on the precise shape of the friction hill, and a linear relation is deduced between G/P and T/P, where T is the difference of the front and back tensions. This is confirmed by experiments on annealed mild-steel strip and it is found also that T/P is approximately equal to the angular arc-of-contact when the torque is zero (Steckel rolling).

A more detailed investigation of the effects of tension, based on the simplest possible hypothesis, indicates that a back tension, Tb, increases the torque per roll by , while a front tension, T f, decreases it by , where r is the fractional reduction in strip thickness and R is the undeformed roll-radius. The theory indicates also that the roll-force decreases linearly with both front and back tensions. Experimental data confirm the theoretical predictions of linearity, and show that the formula for the effect on torque is accurate over a wide range of tensions.
Flexural Stresses in Curved Beams of I- and Box-section
Authors: Anderson C. G.
Published: October 2007

A mathematical and experimental investigation is made of the stresses resulting from the flexure of curved beams of I- and box-section. It is shown that the flanges, if unsupported, distort under the influence of radial stress-components, and are less effective in carrying the circumferential bending stresses than would appear from ordinary methods of calculation. The distortion is accompanied by transverse bending stresses which, in certain circumstances, may be of greater magnitude than the circumferential stresses, and which at the inner radius combine with the circumferential stresses to introduce critical stress conditions. The distortion effects may be limited by using thick, narrow flanges, by ample fillets between the flanges and the webs, by radial gussets and by suitable disposition of the webs in box-sections. Formulae and charts for the estimation of stresses are presented in convenient form for design purposes.
Standardization of Steam Turbo-Generating Plant
Authors: Robinson I. V.
Published: October 2007

“Standardization” is taken to cover (1) simplification of a range of components ; (2) standardization of capacities and of operating conditions; and (3) standardization of station arrangement. The paper deals with aspects of (2) and (3), and notes on auxiliary plant, including condensers, are added. A warning note is sounded, lest standardization should lead to stagnation.

Reference is made to the possibilities of hydrogen-cooling as a means of reducing windage losses and the maximum indivisible weight of stator to be handled.
Industrial Design and its Relation to Machine Design
Authors: Conway H. G.
Published: October 2007

The paper deals with improvement in “machine” design in relation to function (specification, durability, and performance), manufacturing cost (processing, redesign, and collaboration with suppliers), and styling. Conscious attempts at improvement in appearance should, in the author's opinion, be the last stage in the general process of improved machine design.

In regard to styling the author stresses the importance of appearance, the functions of the specialist “industrial” designer dealing with appearance and utility in co-operation with the “mechanical” designer, and the need for training of engineering designers in “composition” (by which is meant “what not to do” rather than creative artistry, which springs perhaps from an intuitive rather than an instructed apprehension). Incidentally, the need to consider the buyers' tastes of the moment is the greater for products that do not outlast contemporary fashions.

Improvement in product design may be brought about by the employment of specialist consultants (who are in continual contact with new materials and ideas); by managements' readiness to improve, and to encourage, rather than frustrate, the creative instinct in designers and engineers; by team concentration upon redesign of particular machines; by training young engineers to be product-conscious; and by the introduction of non-specialist technical literature dealing with design in the broadest sense and with the exploitation of new materials and processes.
Electronic Engine Indicators with Special Reference to Some Recent American Designs
Authors: Vinycomb R. K.
Published: October 2007

For internal combustion engines, the mechanical indicator has been largely superseded by “single-point” systems or by electro-mechanical transducers in conjunction with electronic instruments. After dealing briefly with the history of engine indication and some early electronic devices for this purpose, the paper outlines the characteristics of an ideal indicator.

Most commercially-available indicators now use a variable-capacitance “pick-up”. Three contemporary systems (two American and one British) of this type are described, with details of the pick-ups, basic circuits, and performance under practical operating conditions. This is followed by a description of a radically different type of pick-up developed in the United States. It uses a catenary-shaped diaphragm and a variable-resistance sensitive element. The improved performance realized by this pick-up is explained by reference to its unique design.

In conclusion, the characteristics of all four of the systems described are examined with respect to the ideal indicator.
The Heat Unit
Authors: Griffiths Ezer
Published: October 2007

This paper gives the history of various calories and British thermal units which have been in use.

International agreement has now been reached that the joule (107 ergs) should be the fundamental unit of heat. The advantages of this unit are that it is (1) independent of the intrinsic properties of any particular substance, (2) independent of the temperature scale, and (3) easily realizable in terms of the electrical units.

Calorimetric apparatus nowadays is calibrated by electrical heating and the electrical units are known with high precision. Since the international system of electrical units has now been superseded by the absolute system, it is necessary to express in absolute units the various heat units formerly defined in terms of international electrical units.

The international steam table calorie defined as 1/860 of an international watt hour, when expressed in absolute joules, becomes 4.1868. The other calorie which is defined in terms of the international electrical units is the thermochemical calorie. This, in absolute joules, becomes 4.1840.

Table 1 shows conversion factors to joules.
The Design and Development of the Twin Centaurus Power Plant for the Bristol “Brabazon”
Authors: Norton J. L.
Published: October 2007

The adaptation of eight “Centaurus” engines, grouped in pairs, to drive airscrews presenting only four disks to the air stream in the Bristol “Brabazon”, is described, including their submersion within the wing thickness, and special cooling arrangements. The reasons chosen for the layout of the power plant are given.

Description of the design of the dual-reduction gear includes the primary and auxiliary drives, free wheels, and propeller shafts. The operating system of the propellers is briefly reviewed.

The plant used and programme for testing, including fire precautions and detection and an actual engine fire test, are described.
The New Factory
Authors: Bulger J. G.
Published: October 2007

The building of a new factory is a major project, and the co-ordination of all interests, mechanical, civil, electrical, and administrative, connected therewith forms the subject of the paper.

Special attention is drawn to the appointment of the project manager, his terms of reference, his authority, and his responsibility, upon which is based the organization for co-ordination. Stress is laid on the personal attitude of all concerned, who must sink personal feelings, jealousies, or bias, in favour of the satisfactory conclusion of the project.

A broad plan, prepared by the permanent staff of the company should give as much information as possible to the project manager, who preferably will not be a permanent member of the staff himself. The project manager and his committee will formulate the final plan, and carry the project through to conclusion, but not finality.

Time spent on the site selection is time well spent, since the site is permanent. Attention must be paid to position, labour, foundations, process water disposal, fuel and water, power, housing, and amenities. Considerations of plant, plant layout, buildings, site layout, and services are of considerable importance, many points common to all industries being covered by the paper. Planned progress is essential.

There is no finality to the building of a new factory. The development is handed over by the project manager to the production staff.
The Effect of Speed and Feed on the Mechanics of Metal Cutting
Authors: Chao B. T. , Bisacre G. H.
Published: October 2007

When the cutting speed or feed of a metal cutting tool is increased, the most striking effect is on the rate of tool wear, but there are other changes which take place at the same time. These are changes in the geometry of the chip, tool forces, and tool build-up and surface finish. An attempt is made in this paper to form a logical theory to explain these variations in the mechanics of the process. The problem of tool wear is not attempted.

A series of tests has been conducted on mild steel and copper, over a wide range of speed, feed, and tool angle; and a theory has been developed. The results arrived at are:—

(1) That local temperature in the chip plays an important part in affecting the friction at the chip tool interface.

(2) For many purposes effects due to speed and feed can be treated as functions of the product of speed and feed.

(3) Temperature does not affect the shear strength of the metal directly.

(4) The extent of built-up edge prevailing can be put as a function of the product of speed and feed.
Further Mechanical Aids for the Foundry
Authors: Beech A. S.
Published: October 2007

New mechanical and semi-mechanical devices put into practice in the foundry between 1942 and 1949 are described. They include in the mass-production shop, the moulding machine, brake block production and a modern knocking-out station, sand preparation and reconditioning and a multiple-belt storage hopper. Mechanization in the jobbing foundry is also discussed.
Some Fatigue Tests on Aluminium-alloy and Mild-steel Sheet, with and without Drilled Holes
Authors: Phillips C. E. , Fenner A. J.
Published: October 2007

This paper describes fatigue tests, under pulsating direct stress, of aluminium-alloy and mild-steel panels, with and without central holes, approximately 0·1 inch in thickness and up to 12 inches in maximum width.

Comparison of the results of tests on panels of similar shapes but of different sizes shows that larger panels are relatively weaker.

The influence on the fatigue strength of varying the size of a drilled hole in a wide panel has been explored over a range of hole-diameters from to of the net width. While, in general, the presence of a hole causes a marked reduction in fatigue strength, the smallest holes result in only a slight reduction.
The Design of Flexible Disk Misalignment Couplings
Authors: Wolff P. H. W.
Published: October 2007

This paper gives the results of calculations which were undertaken, in the first instance, to determine the increase in operating range of a disk coupling with skew misalignment which would be obtained by tapering the disks. The results of later investigations concerning the stresses due to “umbrella” deflexions, the vibration frequencies of tapered disks, and the torque buckling of disks of constant thickness, are also presented.

All the results have been obtained by integration of the general differential equation for disk bending.
Extension of the Simple Plastic Theory to Take Account of the Strain-hardening Range
Authors: Roderick J. W. , Heyman J.
Published: October 2007

In the simple plastic theory commonly used for mild steel it is assumed that after yielding has occurred in either tension or compression, straining can continue indefinitely at constant stress. Such an assumption has been found satisfactory for low carbon steels having a plastic range corresponding to eight to ten times the strain at yield, but for steels of greater strength this range is often considerably shorter, and it becomes necessary to take into account the strain-hardening range beyond.

To obtain experimental data, four steels were selected, varying in carbon content from 0·28 to 0·89 per cent, and having widely different stress-strain relations. For each steel a number of simply supported beams of square section were subjected to a symmetrical two-point loading; tension specimens were prepared from the unyielded ends of these beams and tested in a spring-loaded autographic testing machine to determine upper and lower yield stresses. In addition, two tension specimens from each steel were tested in a lever type of machine, and the stress-strain relations through the plastic range and the initial stages of the strain-hardening range were obtained with the aid of a “Gerard” extensometer***. This information gave good support to the theoretical work, whereby the behaviour of these steels in flexure can be correlated with the tensile properties.
The Design of Large Pumping Installations for Low and Medium Heads
Authors: Wauchope G. A. , Humphreys H. P.
Published: October 2007

This paper is concerned with the factors involved in the selection of the most suitable designs of pumping installations, particularly of the larger sizes, and, in the first place, discusses the effects of the different types of pump on the construction of the pumping station. It goes on to demonstrate the relative advantages of different designs over the wide range of specific speeds available.

Methods of determining the most suitable hydraulic characteristics in three typical cases are examined and the effects of these factors on the first cost and running and maintenance costs are considered. As most selections are usually a compromise between the ideal hydraulic characteristics and those available from the pump and prime mover, the relative merits of constant-speed, variable-speed, and variable-pitch impellers are discussed. Certain aspects of the methods in use for priming pumps are considered and the chief causes of pressure surges in pipe-lines are briefly outlined.

The paper concludes with a discussion of the various factors which may decide whether it is desirable that the plant shall be automatically operated, centrally controlled, or individually controlled.
Some Problems of Fluids for Hydraulic Power Transmission
Authors: Bingham A. E.
Published: October 2007

The connexion between aircraft, land, and marine hydraulics is emphasized, especially in regard to the working fluid and the sealing problems. The ideal fluid which would suit all cases does not, as yet, exist. The properties, advantages, and disadvantages of a number of well known, and a few lesser known, fluids are discussed. The fluids include those based on petroleum, castor, water-glycol, halogenated, and synthetic compounds.

The properties covered include viscosity and density, and their variation with temperature and pressure; chemical and toxic effects; bulk modulus or compressibility; water miscibility, and the significance of cloud, pour, and boiling points.

The fire hazard, and its difficulties of assessment in relation to the usual recorded properties and conditions, is noted.

Thermal conductivity, dielectric strength and storage conditions are also considered.

Some of the information, of which much hitherto has been widely scattered, has been derived from recent research, and an attempt has been made to arrange the data in rational form.
Some Factors Affecting Wear on Cemented Carbide Tools
Authors: Trent E. M.
Published: October 2007

Evidence has been obtained that, in extremely severe conditions of friction, fusion occurs at the surface of friction between cemented carbides and steel. It is shown that steel will fuse with tungsten carbide at a temperature between 1,300 and 1,325 deg. C. (2,372 and 2,417 deg. F.). A theory is put forward to account for the “cratering” wear on cemented carbide tools containing free tungsten carbide. According to this theory, a fused layer of an alloy between tungsten carbide and steel is formed at the friction surface and is carried away by the chip. Titanium-tungsten carbide does not fuse with steel so readily, and hence is worn away much less rapidly than tungsten carbide in steel-cutting at high speeds. Micro-examination of worn tool surfaces shows that the type of wear is consistent with this theory. The conditions existing at the tool-work surface are discussed and the type of temperature distribution in the tool near the cutting edge is estimated. It is shown that the temperature distribution near the cutting edge can control the extent of cratering, the “built-up” edge, and deformation of the tool. In the light of the theory, some of the basic properties required in a tool material are discussed.
High-temperature Alloys in Relation to Gas-turbine Design
Authors: Buckle K. L.
Published: October 2007

In order to achieve a thermal efficiency in the gas turbine comparable with that realized in steam practice, a higher turbine-entry temperature is necessary.

Limiting discussion to the combustion and expansion sections of the gas turbine, the paper first indicates that the use of metals in high temperature and stress conditions necessitates a new approach to component design. The phenomena of creep and fatigue assume major importance whilst pure temperature effects, such as expansion and thermal shock, are additional problems. These properties are defined and an indication is given of their significance in the design of combustion chambers, turbine wheels, and blades.

Susceptibility to heat treatment, intended to induce the desired high-temperature properties, is another important factor to be considered in material selection, as are fabrication characteristics. Since the latter govern both detail and general design, the merits of forging, casting, and welding are outlined when applied to high-temperature alloys.

The paper concludes with a survey of the problems likely to be encountered with future materials, particularly ceramics, whilst suggesting that increased efficiency may be obtained by further research on established alloys or by design innovations such as cooling.
Basic Engineering Standards and Their Place in Design
Authors: Adams G. C.
Published: October 2007

In this paper standardization in design is considered. The argument is developed tat the detailed design of the parts of a mechanism demands a logical approach. The designer should state on the drawing, in the simplest possible terms, what he really wants. The necessary range of basic (or abstract) engineering standards, both for him to achieve this aim and to provide for economic production, are given.

The basic standards cover definitions, geometric analysis, ultimate standards of size, basic sizes, limits and fits, measurement, surface texture, drawing practice, standard forms (for example, screw threads), and standards of design. Their nature and scope are examined in general terms and some of the main compromises necessary are discussed.

The necessity is shown for a sound framework, wide enough to cover the normal needs of all engineers. The dangers of a parochial outlook are stressed and the needs of both small and large producers are emphasized. These standards are shown to be the essential preliminary to sound standardization of articles, which should be a natural by-product of sound design. Their main economic value, however, is that they affect every article which the engineer designs.

At the present time there is only a partial framework and much disagreement on details. To standardize articles before agreement has been reached on the approach to detailed design of the articles, leads to difficulties in standardization and sometimes to bad standards. Several good solutions can be propounded for most problems, and many different ones are in local use. A single, wide, and all-embracing plan which can be used by everyone is needed. Education and explanation can then lead to general use, to the lasting advantage of the engineering industry.
Leakage of Air through Labyrinth Glands of Staggered Type
Authors: Kearton W. J. , Keh T. H.
Published: October 2007

A simplified theory is presented for the flow of air through a single orifice or constriction. This theory is then extended to cover the flow of air through a labyrinth gland having several constrictions of equal area. Experiments are made over a wide range of pressure ratios to determine the coefficient of discharge for a single annular constriction having a small clearance. It is found that the curve has the same general characteristics as that for a circular sharp-edged orifice. The discharge coefficients are then used to calculate the critical ratio of inlet pressure to outlet pressure for a labyrinth gland. The results obtained agree well with experiments on a stationary labyrinth gland of the staggered type in which the number of constrictions may be varied from one to fourteen.

The theoretical pressure distribution is derived and compared with experimental values under conditions where the pressure drop across the last constriction is either less or greater than the critical value. Finally, the coefficients of discharge are obtained experimentally for the final constriction and for the preceding n-1 constrictions in a gland having n constrictions. It is concluded that the carry-over effect in a staggered gland is small.
Design and Operation of a Large Heat Transfer Installation
Authors: Brearley N.
Published: October 2007

Jacketing by a transfer medium of the condensing vapour kind is a suitable method for heating many process units to temperatures of about 300 deg. C. (572 deg. F.) when fine control is necessary. The mixture of diphenyl and diphenyl oxide known as Dowtherm “A” has a good relation between vapour pressure and temperature for such a purpose. In the paper the other relevant properties are discussed.

The principle of operation of a circulating system and the design of an installation of vaporizing and auxiliary equipment having a rated output of 11,000,000 B.Th.U. per hr. are described with reference to the special problems presented by Dowtherm owing to its inflammability, high freezing point, searching nature, scouring properties, and possibility of degradation.

Preliminary work on two possible alternative materials with lower freezing points and less propensity to leakage is briefly mentioned.
The Mechanism of Work-hardening of Metals
Authors: Mott N. F.
Published: October 2007

The most striking feature of the deformation of metals is the formation of slip lines. Recent investigations suggest that, when formed at low temperatures, each slip line is the result of a displacement of the material along a single lattice plane through a distance of about a thousand atomic diameters. Moreover, there is much evidence that the steps on the surface which appear as slip bands attain their full height in a small fraction of a second, though their length may thereafter increase slowly. At higher temperatures and at slow rates of strain the slip bands appear, under the electron microscope, as clusters of lines about a hundred atomic diameters apart. The origin of slip lines, the reason for this clustering and the cause of work-hardening are discussed. The two conceptions used in the discussion are the dislocation line and the vacant lattice site.

Slip lines are believed to have their origin in a certain arrangement of dislocation lines of frequent occurrence in the interior of the crystal. These are known as Frank-Read sources; their relation to recent work on the growth of crystals is shown. Where a slip line terminates dislocations must remain in the crystal; to the internal strains round these is ascribed work-hardening, much as in Taylor's theory of 1934†. It is now, however, possible to explain what it is that stabilizes the dislocations and prevents them from moving back when the stress is released.

Finally, vacant lattice sites are shown to be formed in a cold-worked material. If the temperature is high enough for them to diffuse, they soften the material round the slip band and allow the observed clusters to form. They also play a part in producing the observed “fragmentation” of cold-worked material.
Effects of Inertia on Flow of Steam through Nozzles and Blading of Axial-flow Turbines
Authors: Kearton W. J.
Published: October 2007

A method is given for calculating the radial distribution of pressure in a steam turbine with long blades, the conditions for radial equilibrium, for continuity, and for energy balance being satisfied simultaneously. An example, illustrating the application of the method, shows that if there is pure impulse at the root of the blade, an appreciable degree of reaction may be reached at the outer end of the blade. It is shown that if the steam flow is to be parallel to the axis of the turbine then the variation of nozzle outlet angle with change of radius depends on the steam velocity at the inner radius. An alternative theoretical analysis of the problem is given which yields quickly the radial distribution of pressure where the nozzle outlet angle is uniform. This analysis is extended to give the degree of reaction at the blade tip in terms of that at the blade root.

The paper concludes with a brief note showing that in geometrically similar turbines operating with the same blade speed, but different speeds of rotation, the radial distribution of pressure is the same.
The Design and Operation of Dunston “B” Generating Station with Particular Reference to 50-megawatt Turbo-alternators Unitized with Reheater Boilers
Authors: Howell A. , Jackson J. B.
Published: October 2007

Two 50-megawatt turbo-alternators unitized with reheater boilers were commissioned at Dunston “B” generating station towards the end of the year 1950, and ranked as the most efficient generating plant owned by the British Electricity Authority during the year 1951.

In Part I of the paper are shown the changes in design compared with the original plant which was commissioned seventeen years previously.

In Part II plant staffing and staff training are discussed and details of operating experience are given, including methods adopted for overcoming the initial plant troubles and the procedure eventually evolved for starting-up and shutting-down, and, in particular, the method adopted to permit full load to be achieved in hours from starting-up.

Performance and “outage” figures for 1951 are discussed and analysed and results of tests are tabulated, including load throw-off tests and monthly performance tests for the two Units 5 and 6.

It is concluded that unitized generating plant can be controlled so closely as to achieve test conditions and performance in commercial operation, but that attention needs to be drawn to detailed improvements in design and workmanship. In particular, the need is stressed for more care in making joints and tightening bolts for high-pressure work.

Future economies and improvements proposed as a result of experience are mentioned.
Contemporary Methods of Watch Production
Authors: Fell R. A. , Indermuhle P.
Published: October 2007

There is at present no written matter in the English language on watch production, the industry having died out in Britain some thirty years ago. The aim of this paper is to provide the engineer who is not a specialist in the subject with a background knowledge of the methods used in the production of watch components and the special difficulties encountered in watch manufacture.

In the first part of the paper the historical development of the watch and the general principles of design are briefly reviewed. A fifteen-jewelled man's wrist-watch with lever escapement is taken as a typical example, in which the features commonly encountered are examined in more detail and the small size of the pinions and pivots is emphasized.

The latter part of the paper is devoted to the techniques used in the production of the components (the plates and bridges, turned parts, wheels and pinions, escapement, and balance); their final assembly; and the oiling, springing, and timing, of the finished watch. A general note on the three main categories of watches is amplified by figures illustrating the performance actually attained by a wrist-watch of the highest grade.
The Problem of Fuel-oil Ash Deposition in Open-cycle Gas Turbines
Authors: Bowden A. T. , Draper P. , Rowling H.
Published: October 2007

The loss of power due to the deposition of fuel-oil ash on the turbine blades at present limits the use of boiler fuels in open-cycle gas turbines, and therefore prevents the more widespread application of this form of prime mover in the marine and industrial fields.

The nature and occurrence of the ash-forming constituents are discussed, followed by consideration of the possibilities of removal of these from the oil. There appears to be no solution along these lines nor by removal of the ash from the gas stream. The basic factors controlling deposition of ash are still not fully understood and therefore further experimental work is required. However, a method which gives a considerable reduction in deposition has been discovered. In this, combustion of the fuel droplets is controlled so that each droplet burns down and leaves the combustion chamber as a hard, dry, carbon particle containing an appreciable proportion of the ash. The combustion loss due to this unburnt carbon is less than 1 per cent. Long-term engine tests are now required to assess the practical use of the method.

Another means of reducing deposition which appears to offer considerable promise is the use of various additives to the fuel or gas stream. Of those tested the oxides of silicon, zinc, and magnesium were the most effective.
Design Features of Certain British Power Stations
Authors: Whetman S. D. , Powell A. E.
Published: October 2007

The paper, of which the following is a summary, is a Supply Section paper of the Institution of Electrical Engineers, and was presented for discussion at a Joint Meeting of that Institution and the Institution of Mechanical Engineers on 5th March 1953 at the Institution of Electrical Engineers, London. The paper in full, together with a full report of the discussion, will be published by the Institution of Electrical Engineers.
Design of Precision Grinding Machines
Authors: Asbridge G. H.
Published: October 2007

In this paper are put forward the basic principles under which all grinding machines, irrespective of size or type, must be constructed. The chief problems facing the designer of precision grinding machines are discussed, together with the essential elements and physical components. The choice of solutions which seem to offer the most promising future developments is suggested. The factors affecting the design of grinding machines—cost, ease of maintenance, and the influence of the user—and the essential elements—rigidity, accuracy, and constancy, are discussed. Mechanical and hydraulic traverse mechanisms are compared and a brief description is given of a typical hydraulic system. Although mechanical methods of traverse have been giving way to hydraulic systems, the author considers that with the improved electrical control gear available there may be a reversion to mechanical traverse mechanisms on account of their simplicity and reliability.

The influences of the wheel-head and wheel-head spindles are discussed. The two lines of approach that wheel-head design and wheel-head speeds will follow during the next few years is suggested. Work-head and work-head drive arrangements are described; followed by the main features of universal machines and machines arranged for automatic operation.

Finally, methods and mechanisms are described for obtaining concave and convex camber with roll-grinding machines.
Nuclear Reactors and Power Production
Authors: Hinton Christopher
Published: October 2007

This lecture deals with the design and construction of nuclear reactors, and particularly of types suitable for the generation of power. To introduce this a detailed description is given of the British Experimental Pile (BEPO) at Harwell. This is a typical ‘thermal’ reactor on a small scale, using natural uranium as fuel and graphite as moderator; it is air-cooled and the shielding and control arrangements illustrate general practice. There follows an account of some of the engineering and construction problems met in the erection of the Windscale piles, and the solutions achieved.

The problems involved in designing power-producing reactors are discussed. The choice of materials in the reacting core is restricted by nuclear physical considerations; large absorbers of neutrons cannot be used. There is a conflict between the demand for high temperatures to give satisfactory thermal efficiency and the limitations imposed by the metallurgical properties of the fuel elements and by the coolants employable. The safety aspect of design is considered and the influence of the coolant described; certain types of reactor can be designed to be inherently safe even in the event of a coolant failure but with others there is the risk of reaching a supercritical condition, and the effect of this is discussed.

The possible reactors may be divided into two groups: those which use ‘thermal’ neutrons and are similar in principle to BEPO, and those which use ‘intermediate’ or ‘fast’ neutrons and have a much smaller core size. Within each group are alternatives provided by differences in fuel, moderator, and coolant. A number of these are reviewed with general indications of their size, and some of the more detailed problems associated with their design are considered. The large reduction in core size resulting from the use of ‘fast’ neutrons leads to acute problems of heat transfer and, though the fuel investment is much less, the fissile material content of the fuel used must be much higher. One or two possibilities for the more distant future are briefly mentioned.

Prospects for the large-scale development of nuclear power are discussed, and it is argued that the replacement of coal-fired boilers by nuclear reactors as the heat source at power stations should, before many years have passed, be economically sound and is further justifiable as it would help to reduce the recurrent shortage of coal. A possible national scheme is outlined in which thermal reactors would be built in the first stage; these would produce supplies of fissile material as well as power, and this material would later be used in ‘breeder’ or ‘converter’ reactors in the second stage; these reactors should be self-sustaining in fuel after the initial charge.

An Appendix is included which gives a simple explanation of the underlying theory of atomic energy and of the terms used in the lecture.
Corrosion Aspects of the Vanadium Problem in Gas Turbines
Authors: Frederick S. H. , Eden T. F.
Published: October 2007

The effect of V2O5 and mixtures of V2O5 and Na2SO4 on turbine fouling and corrosion is discussed. Laboratory tests have shown that none of the commercially available alloys is immune from attack when these mixtures are molten, that is, at temperatures above 650 deg. C. Nickel base heat resisting alloys of the Nimonic type offer higher resistance to attack than the austenitic steels and some degree of protection is afforded by electro-deposited coatings of chromium.

Steels and heat resisting alloys are not attacked to any significant extent at temperatures below the melting point of the ash, but copper base alloys suffer considerable corrosion at temperatures as low as 500 deg. C.

A detailed investigation of the effect of additives on the corrosion rate of V2O5-Na2SO4 ashes indicates that corrosion can be considerably reduced, and that such a method of approach is promising. Suitable additions may be made by a mixture of oil or water soluble materials with the fuel, by suspension in the fuel, or by separate injection into the combustion chamber with the object of reducing corrosion and deposition.

Laboratory corrosion tests, using ash additives such as ZnO, Al2O3, and kieselguhr, have shown that the rate of attack can be greatly accelerated if the additive is present in certain critical proportions, but when this is exceeded, corrosion is considerably reduced. With MgO, however, no such increase in attack was noted. Rig tests have confirmed some of the beneficial effect of additives.
Measurement and Analysis of Rolling Loads in a Large Hot Plate Mill
Authors: Stewartson R.
Published: October 2007

Instruments for measuring rolling loads have been constructed for insertion between the screw and the top bearing chocks of a heavy plate mill. They have been accommodated in a limited space and designed to attempt the measurement of non-uniformly applied loads.

The load indications during the rolling of a varied programme for plates of different size have been analysed and compared with three roll-load formulae. That due to Sims seems to give the best agreement, and the majority of the calculations for reductions over 10 per cent lie within ±25 per cent of the measurements, whereas the other formulae show discrepancies often exceeding 50 per cent. For reductions less than 10 per cent all three formulae show similar trends, giving values in general very much lower than those obtained with the instruments.

Although the instruments have proved satisfactory for short trials, certain features will be modified in models which are now being designed with a view to more permanent installation.
Practical Training in Industry for the Graduate in Mechanical Engineering: Part IV
Authors: Pope J. A.
Published: October 2007

Engineering is not only a science but also an art. With the ever-increasing scientific content of an engineering graduate's training, less and less time is devoted to workshop practice, machine drawing, and design. The engineering graduate leaving the university today is much less an engineer than his counterpart was in 1910. In fact, universities do not produce engineers, they train students in engineering science and it is left to industry to complete the graduate's training.

The common pattern of training for the graduate engineer is direct from school to the university for three years followed, after graduation, by two years' practical training. The author suggests an alternative scheme of one year in industry after leaving school to be followed by three years in a university, the graduate's training being completed by a further year's training in industry. The scheme is called ‘the thick sandwich’. Its main advantages are that (1) the undergraduate knows what engineering is when he joins a university, (2) it will tend to produce men with a stronger bias towards the production side of the industry, and (3) men who commence their training in the shops will be, after graduation, more acceptable to the personnel of the engineering industry.
Technical Features of the New British Standard System of Limits and Fits
Authors: Conway H. G.
Published: October 2007

This paper discusses the new British Standard for limits and fits for Engineering (B.S. 1916), outlining in particular the technical features and explaining how the system has been built up. A brief historical review of other systems is made, their faults being referred to. The prospects of adoption of an equivalent system by the United States and a corresponding decision already taken by Canada are mentioned.

The paper goes on to discuss the theoretical requirements of a good tolerance system and then compares the new standard with the theoretical desiderata. The technical reason for each particular diameter step, tolerance value, or shaft or hole allowance is given, supplementing the necessarily bare data given in the standard itself.

Indications are given of the future extensions of the system which are likely to be made following international discussions in relation to tolerances for small diameters as used in the horological industry, tolerances for precision fits and fine quality gauges, and tolerances for large diameters up to about 6 feet. The practical difficulties in determining and using tolerances in diameters above 20 inches are considered in some detail, and a plea is made for discussion and information on this matter.
The Practical Application of the New British Standard System of Limits and Fits
Authors: Pearmain G. J.
Published: October 2007

This paper suggests methods by which the new British Standard system for limits and fits can be most efficiently applied in industry, and proposes a method of approach by which series of fits for various purposes can be selected from those shown in the British Standard. It refers particularly to Part II of the Standard which gives data on the application of various types of fit.

The choice of tolerances is discussed in relation to machine capabilities and fit requirements, and a series of fits for general engineering requirements is proposed. Methods of assisting the correct application of tolerances and fits in the design stage of a piece of equipment are suggested, and the use of methods of selective assembly is shown to be practicable, using standard limits. Assembly fits for ball and roller bearings are discussed, and it is suggested that a standard series of such assembly fits should be established.
An Experimental Investigation into the Effect of Fuel Addition to Intake Air on the Performance of a Compression-ignition Engine
Authors: Lyn W. T.
Published: October 2007

The investigation arose from a programme of research into the means of reducing combustion noise and engine roughness in a compression-ignition engine. Information on pre-flame reactions in spark-ignition engines from published literature indicates that these reactions, which yield active partial products of combustion that finally lead to the auto-ignition of the end gas, or ‘knock’, may reduce the ignition delay in a compression-ignition engine and contribute to the smooth running of the engine.

Preliminary tests with part of the fuel introduced with the intake air in the form of spray confirmed such a view. They showed how, by slow oxidation of the aspirated fuel, the compression pressure is increased and the ignition delay of the main fuel is reduced with consequent smoothing of the pressure diagram and elimination of combustion noise. The effects on combustion and performance under various loads and speeds are presented, it being found that overall thermal efficiency is improved at high load but made worse at low load.

Further investigations were then carried out on the various factors that may have effects on the result of introducing fuel with the intake air. Among these were the types of fuel used for the aspirated as well as the main charge, combustion chamber design, compression ratio, and timing of both parts of the charge. An analysis is made of the processes of combustion under such conditions and a theory advanced to account for the phenomena observed. It is concluded that the lean aspirated mixture does not proceed to complete combustion. The use of intake spray was found particularly effective when the main fuel was of low ignition quality.

The technique of using the slow oxidation of the aspirated fuel was then applied to study the ignition of various hydrocarbons in a compression-ignition engine. It is shown that the differences in ignition delay of various fuels lie chiefly in the chemical part of the delay while the physical part remains essentially constant in spite of widely different physical properties of the fuel. It is shown also that with the use of intake spray, the compression-ignition engine can run on any fuel irrespective of its cetane number and with only small differences in thermal efficiency.

Finally, the effect of some additives on the reactions of the aspirated fuel and the ignition of the main fuel were studied. The results showed that the reactions were suppressed by the addition of formaldehyde and tetraethyl lead and slightly accelerated by nitrogen peroxides. The indication was that the reaction is of the ‘low-temperature’ mode. This is discussed in relation to the recently published works on oxidation of hydrocarbons in general and the reactions leading to knock in the spark-ignition engine.
The Impact of Development and Research on Production and Design
Authors: Leedham L. H.
Published: October 2007

The paper deals with some technical activities which are of particular importance in relation to production, but which are not always recognized as having a direct bearing thereon. Simplification of product, functional development and production research provide means by which existing facilities may be made to yield greater output, that is, to increase production efficiency. They also make it certain that industry will in the future employ those processes which ensure the maximum economic gain.

The attitude of the mechanical engineer to production techniques as a part of design also receives consideration, together with the desirability of infusing designers and draughtsmen with a greater interest in new methods. The responsibility of industry in affording training for this purpose is also discussed.

The lack of adequate support for production research is emphasized, while attention is drawn to the difficulties of small firms in benefiting from the results of research and development work on new processes.
The Calculation of Mass Transfer Rates in Absorption, Vaporization, Condensation and Combustion Processes
Authors: Spalding D. B.
Published: October 2007

Mass transfer processes are shown to be capable of description in terms (a) of an equation, which is the same for all types of mass transfer, relating the mass transfer rate to the Reynolds number and other conditions; and (6) of a driving force, called the transfer number, which appears in the common equation but has a different form for each type of mass transfer. Transfer numbers for absorption, vaporization, condensation, and the combustion of carbon, metals, and liquid fuels are derived. The mass transfer rates predicted in combustion are compared with experimental data.