bluuebunny/crossref_metadata_2025_split huggingface dataset:
Transfer Moulding
Authors: Freund M. 
Published: October 2007

Since the early days of the commercial plastics moulding industry, injection moulding principles have been successfully applied. Compression moulding technique has achieved a high economic standard by the design of multiple-impression moulds, and when transfer moulding technique has been applied it has mainly been for technical reasons. Recent developments, however, make it possible to use transfer moulding on a large scale, and it can now compete with the orthodox compression moulding in economy and efficiency. Existing machines can be used for the transfer method, but special presses adapted or built for this purpose will give a better service. Consideration of the engineering fundamentals of the transfer moulding process will contribute to the economy of tooling; the tooling is influenced by the presses used, and the plastics moulding engineer will have to co-ordinate all production items for successful competition with compression moulding. The strength of the finished mouldings, too, is influenced by the manufacturing method. Further developments in machines, tooling, and methods are necessary if conventional moulding methods are to be replaced entirely in mass-production applications.
Aircraft Wheel Brakes
Authors: Robson D. A. L. 
Published: October 2007

In designing brakes for the landing run, account should be taken of aerodynamic forces acting on the aircraft that reduce the ground reaction in addition to helping to retard the aircraft. There are good grounds for designing brakes with a limiting torque, because most British tail-wheel type aircraft will nose over if the brake drag exceeds about 0·2–0·3 times the aircraft weight, and with tricycle landing gear the loads imposed on the nose-wheel structure during severe braking may be critical; furthermore, the danger from bursting a tyre, owing to locking the wheel, cannot be ignored. Calculations made for a hypothetical aircraft indicate that little is gained by designing for a brake drag in excess of about 0·3 times the aircraft weight. Brakes are used both for steering and limiting the speed of the aircraft when taxi-ing, and in consequence, a very large amount of energy may have to be dissipated by them. Shoe brakes are standard equipment on German aircraft, and are also widely used in America, but use on British aircraft is confined to the smallest types. British designers have used expander-tube brakes almost exclusively, but disk brakes—popular in America—are now receiving close attention in this country. The British system of brake control is to use finger operation, with a differential mechanism coupled to the rudder control, but in most other countries foot pedals are employed. The British system necessitates power operation almost always, but direct operation is possible when foot pedals are used. Pneumatic power transmission for brake operation has been widely used on British aircraft, but most other countries have adopted hydraulic operation.
The Production of Small Worm Gears for Experimental Work
Authors: Gunner A. M. 
Published: October 2007

Small worm gear drives are a common feature in the design of many types of apparatus, and the following description of the methods used for producing them in an experimental establishment may be of interest. Quantities are small, one or two to each pattern being the general rule, but there is certainly no lack of variety. The worms and wheels most often called for range in size up to 1½ inches and 6 inches diameter respectively, while pitches vary from 10 to 60 d.p. (diametral pitch). Addendum and dedendum proportions of 1/ PN and 1·25/ PN have been standardized, and a pressure angle of 20 deg. is adopted throughout. The gears are designed as hollow-faced helical (spiral) gears, and all calculations are based on the normal pitch. This is to enable standard hobs and cutters to be used for the worms. The shaft angle is usually 90 deg., but the angle of crossing may be varied up to 10 deg. either way on the particular machine employed for cutting the wheels. For many applications, backlash must be reduced to the very minimum consistent with smooth running; and to avoid the extreme accuracy of workmanship which an exact centre distance would necessitate, provision is usually made for adjustment of the worm. Although the Reinecker tangential feed method of worm wheel generation by a single-point tool —representing one tooth of a hob—is generally known, very little information on cutter forming is available. The method outlined was developed at the Admiralty Research Laboratory. Given the use of a modern worm grinder (not available), it should be possible to profile-relief grind these cutters after hardening.
An X-Ray Method of Measuring Poisson's Ratio
Authors: Hanstock R. F. , Lloyd E. H. 
Published: October 2007

The paper describes the measurement of Poisson's ratio in metals by an X-ray diffraction method. The specimen, which is a small tensile test piece, is examined at various loads by a high-angle “back-reflection” X-ray technique. At any load (the value of which need not be known) X-ray patterns are obtained for various angular settings of the specimen relative to the incident X-ray beam, and, for each setting, the shift of the diffraction lines from their original position gives the strain in a direction normal to the reflecting crystallographic planes. The strains corresponding to various angular settings of the specimen, for any one load, give a linear graph when plotted against a simple function of the orientation of these crystallographic planes, and from this graph the value of Poisson's ratio is directly obtained. Experimental results are quoted for the aluminium alloy known as “Hiduminium RR.56”. The results obtained for various elastic loads are consistent within the experimental error, the resulting value of Poisson's ratio being 0·36. It is concluded that the method described is capable of an accuracy at least as good as that of the ordinary mechanical method, and that it has the additional advantage of providing values which apply to a single set of crystallographic planes in a polycrystalline metal.
Fuel Systems for the Aero-Gas Turbine
Authors: Watson E. A. 
Published: October 2007

The purpose of the paper is to give an account of the problems associated with the development of the fuel systems of those aero-gas turbines with which the author has been principally associated. While, therefore, it cannot claim to cover all aero-gas turbines, the general problems involved are common to all the turbine units under development, so it is hoped that the paper will be of general, as well as specific, interest. Even so, the author has found very great difficulty in compressing some six years of very intensive work carried out by a large team of engineers into the space of one paper. Much important work has been omitted and other work compressed into small space, but it is hoped that it has been possible to give a fairly comprehensive treatment of certain particular developments while at the same time making clear the fundamental principles on which these have been based. The paper is divided into two sections, the first dealing with the supply of the fuel in the appropriate quantity, and the second covering the atomization of the fuel preparatory to its evaporation and combustion. As far as possible, the two sections will be treated as separate entities, although they are very closely interrelated, since the type of atomizer has an important bearing on the fuel system. In studying the paper, therefore, it may (for example) be necessary to refer to certain items in the second section before the first can be fully appreciated.
Some Recent Developments in the Technique of Radio Valve Manufacture
Authors: Davies J. W. , Gardiner H. W. B. , Gomm W. H. 
Published: October 2007

There are many points in the construction of thermionic valves of general interest to the engineer, and the purpose of this paper is to bring some of these points to the knowledge of mechanical engineers in other fields than valve manufacture. It is not possible to cover all the aspects, but mention will be made to a few of the later developments that besides being of interest may find useful application in other spheres. The principles of construction, the materials used, and the forms and types of various components—cathodes, grids, and anodes—are touched upon. The joining of glass and metal is dealt with, and notes on the machines used are given. The paper ends with particulars of the assembly processes, and tables showing the various types of join in common use and their application in valve manufacture.
The Tensile Yield Strength of Certain Steels under Suddenly Applied Loads
Authors: Warnock F. V. , Brennan J. B. 
Published: October 2007

Dynamic tensile yield stresses are determined for eight steels, including one mild steel, two plain carbon steels, two carbon manganese steels, one heat-treated alloy, and two cast steels. The dynamic loads are applied by means of an impact machine of the falling weight type. An attachment is fitted to this machine to enable the peak load to be reached in 3 milli-seconds (0·003 second). Supplementary tests, in which the time to reach the peak load is 1 milli-second, are carried out on three of the steels. Electrical resistance strain gauges mounted directly on the specimens are used to record the loads. Comparison with static values reveals an increase in yield stress of from 21 to 36 per cent for the carbon steels under dynamic loading. This increase diminishes with increase in static yield strength. The annealed cast steels behave in a similar manner to the carbon steels, but the heat-treated alloy steel shows no appreciable increase in yield strength with increase in rate of loading. Comparison is also effected with some results of other investigators. A theory is put forward to account for the variation in sensitivity of yield strength to load rate. A division of tensile tests into three main types, on a basis of rate of loading, is suggested for future work.
The Mechanical Differential Analyser: Its Principles, Development, and Applications
Authors: Rose H. E. 
Published: October 2007

In the physical sciences differential equations are encountered which are either extremely difficult or impossible to solve by formal methods. For the evaluations of such equations a number of numerical and graphical methods have been developed, together with electrical and other analogues for their direct assessment when the numerical or graphical methods are not practicable. Each analogue will evaluate but one type of equation; the differential analyser—which is not an analogue in this sense but a machine for performing mathematical operations—will, however, evaluate any differential equation (within the capacity of the machine) and present the solution in graphical or tabular form. In the paper the mechanization of integration and other algebraic operations are discussed, and a “non-linear” vibration problem is used as an example of the setting-up and operation of the machine for the solution of a differential equation. Points of special interest in the design and construction of these machines are discussed together with an account of the existing machines. A number of problems of special interest that have been solved by use of the machines are considered and possible lines of development are discussed.
The Calculation of Roll Force and Torque in Cold Strip Rolling with Tensions
Authors: Bland D. R. , Ford Hugh 
Published: October 2007

From an approximate theory, equations are derived for roll force and torque with and without front and back tensions applied to the strip. Where tensions are applied the calculations for each pass take about an hour; without tensions, and with the use of curves given in this paper, they can be carried out in ten minutes. The accuracy of the calculations without tensions is within about 15 per cent. At the end of the paper there is a discussion of the energy relationships in rolling. At present this should be considered as speculative in character.
The Calculation of Compressible Fluid Flow by the Use of a Generalized Entropy Chart
Authors: Kestin J. , Oppenheim A. K. 
Published: October 2007

Calculations of the flow of gases in pipes or ducts of varying cross-sections are important in the design of turbines and compressors, nozzles for various applications, exhaust or radiator ducts, thrust augmenting devices, etc. Provided certain simplifying assumptions are made, there is no difficulty in writing down the basic equations, but when the velocities are comparable to that of sound and compressibility effects cannot therefore be neglected, the solution of the transcendental equations present difficulties which hinder a clear discussion of the physical phenomena. Here the problem is solved by the use of a generalized entropy chart, off which results may be directly read. For example, if the conditions in the reservoir from which the gas is assumed to be discharged are known, the complete conditions at any given cross-section may be read off when two parameters at the section considered are specified. The parameters may include the velocity, pressure, density, temperature, local Mach number, local velocity of sound, area of cross-section, mass flow per unit area, momentum per second, etc. The method is not confined to isentropic flows and may be applied to such problems as the flow in straight pipes or convergent and divergent nozzles including losses by either friction or condensation shocks. The co-ordinates of the chart are: dimensionless entropy σ = ( s— s0) J/R and dimensionless enthalpy ι = h/h0 = T/T0 where the meaning of the symbols is given later. All other variables are expressed in terms of these two co-ordinates and tables for several values of the ratio of specific heats are included to facilitate the drawing of such charts. The method does not aim at presenting new facts, but its usefulness lies in the provision of a comprehensive graphical means of calculating one-dimensional flow of compressible fluids. The charts lend themselves to the construction of a mechanical device for simplifying their use, such as a portable scale with sliding curves.
Chart for the Investigation of Thermodynamic Cycles in Internal Combustion Engines and Turbines
Authors: Gilchrist J. M. 
Published: October 2007

The development of the internal combustion turbine engine has reawakened interest in the study of thermodynamic problems associated with internal combustion engines. Graphical solutions find favour because ( a) widely varying mixtures of gases are used in modern engines, ( b) the specific heats of the gases vary with temperature and pressure, and ( c) the complete combustion of hydrogen, carbon, etc., cannot occur at high temperatures owing to dissociation. In the paper it is shown by suitable selection of scales how the temperature-internal energy graph may be used to indicate enthalpy, and, for engine expansions, the work done and the energy supplied. In turbines and turbo-compressors the heat drop, velocity change, losses, etc., are given by readings from the temperature and internal energy graph. The method is applied to a general cycle which embraces the Otto, Diesel, Atkinson, Humphrey, etc., cycles. To determine the work done and efficiency calculation is eliminated entirely. An indicator diagram taken from an oil engine is examined and the heat exchange for arbitrarily chosen parts of the cycle estimated. Internal combustion turbine cycles are discussed and the advantages of stage reheating and inter-cooling demonstrated. Energy-mixture strength tables, for temperature intervals of 200 deg. C. (360 deg. F.), are supplied for mixtures between 100 per cent weak and 20 per cent rich.
The Distribution of Load in Screw Threads
Authors: Sopwith D. G. 
Published: October 2007

The distribution of load along the length of a nut is not uniform owing to the strains set up in the bolt and nut under load. These strains are analysed and the load distribution along the thread helix deduced. It is shown that the load may be taken as concentrated at mid-depth of the threads. In the normal bolt and nut case the maximum intensity of loading occurs at the bearing face of the nut, and may be from two to four or more times the mean, depending on the thread form, the proportions of the members, and the degree of lubrication; the maximum intensity is almost independent of the length of nut (unless yielding occurs). Possible methods of improving the load distribution are discussed—differential pitch, tapered threads, and the use of a softer material for the nut. The load distribution in the turnbuckle case is more favourable than in the bolt and nut case, and can theoretically be made uniform by suitably boring out the inner and shaping the outer member; this condition can be approached in practice by the use of “tension nuts”. The effect of yielding on the load distribution is discussed. Experimental confirmation of some of the results is included.
District Heating
Authors: Stubbs A. 
Published: October 2007

This paper regards district heating as a service intended to satisfy the space heating and domestic hot-water requirements of the public. It sets out a complete scheme for a large town of 250,000 people in such a manner as to show the values of the parts as well as the value of the whole. The build-up of the district heating load is conveniently set out under the headings: ( a) industrial and commercial, ( b) community, and ( c) housing, whilst the engineering and economic features are related to the consumers, the sub- and main-distribution, and generation. District heat is low-grade energy, and its generation is properly associated with the generation of electricity which is high-grade energy. In taking advantage of combined generation of heat and electricity, consideration is given to the already highly organized state of the electricity supply. The conclusion deals with the costs and overall fuel economy and does not deal with improved amenities which, in the opening part of the paper, are taken for granted.
Modernization of a Coal-Discharging Depot
Authors: Shoosmith G. T. 
Published: October 2007

The paper describes the modernization of a coal-discharging depot originally equipped with hydraulic transporters. The steps taken to enable the jetty to withstand a greatly increased loading are given, and the crane rail girders of special fabricated type are described. The relative merits of various types of unloader are discussed, and the reasons given for adopting electric luffing cranes. The principal features of the special electric cranes installed are described, together with the reasons for adopting certain unusual features, and the provisions made for ease of maintenance and interchangeability of mechanical parts. The system of electrical control adopted is described. The design and operation of grabbing cranes is compared with that of normal cargo cranes. The question of load balancing for cranes is considered and calculations given of speed, acceleration and power consumption for similar cranes without any balancing, and with varying degrees of balancing of the load. The effect of varying height of lift on power consumption is shown graphically. The importance of low inertia of the moving parts of high-speed cranes is emphasized, together with comments on the methods which can be adopted to achieve this end. The design of crane ropes and sheaves and the effect of the reverse bending of crane ropes is discussed briefly, and figures are given of rope life with various designs of grabbing cranes. The importance of high rope-diameter/sheave-diameter ratio is stressed. A brief description is given of a special form of crane weighgear used for the first time on the new cranes at the depot. The question of grab design is discussed briefly, with particular reference to coal handling, and results are given of different designs of grabs dealing with various classes of coal under normal operating conditions. An outline is given of the method of erecting the new cranes without interrupting the working of the depot.
Cinematography in Engineering
Authors: Bulleid H. A. V. 
Published: October 2007

The cinematograph has become indispensable to the modern engineer, and is widely employed as an analytical, recording, and educational medium. Of these, the first only is dealt with in this paper; the others involving, in addition to an essential engineering precision, the artistic and technical resources of film construction. The author deals with the analytical aspect in relation to apparatus, detailing minimum equipment and scope; straight records, with a standardized set-up; special records, with data on camera speed; complex images and multiple exposures; high-speed cinematography, and notes on special apparatus; low-speed cinematography, including animation; special methods for recording hidden transients; X-ray, infra-red, and micro-cinematography, and simpler alternatives. The last section describes typical cases in which, for a variety of reasons, cinematography is not the best analytical tool to use. The paper concludes with sections on the marking, developing, recording, and printing of film records, and describes suitable methods and apparatus for analysing the results. Ten excerpts from 16 mm. films illustrate some of the more important applications described.
Invention and Sifting Out Engineering Facts
Authors: Bailey E. G. 
Published: October 2007

The subject of invention is discussed with a view to increasing the number and value of inventions. The relation between research and invention is explained with a plea that research should be so conducted that more valuable inventions will be forthcoming. The various incentives to invent are listed, and the usual important steps actually required in making inventions are enumerated in a manner that will enable others to follow them. The important steps in reducing an invention to practice are given for the guidance of those interested. Some illustrations from the author's experience show how simple is the process of inventing when there is an incentive. The present trends and future needs for invention in different fields are discussed under the headings of ( a) products and processes, ( b) communications, ( c) transportation, and ( d) power and heat. The sifting out of facts in the engineering field results in only the good and useful surviving. The question is posed as to why facts within the area of human relations cannot be dealt with in a similar manner.