Science Becomes Servant to the Engineer!
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Control, and Special Production Processes Once the Perquisite of Laboratories, Have Been Adapted to Meet the More Rugged Demands of Everyday
Manufacture
RECENTLY developed is an intake manifold for multi-cylindered engines, so designed as to increase the efficiency of the unit by precise control of the fuel-mixture volume as introduced into the cylinders. In addition, it ensures thorough mixing and heating Of the fuel, and sets up turbulence which restricts the precipitation of fuel on the manifold walls. The invention has been tested in use by a large transport company, which obtained 10 m.p.g. as against 81 m.p.g. with the ordinary type of manifold. Road tests indicated a reduction of 27 per cent, in the amount of fuel consumed at 20 m.p.h., and of 17.7 per cent. at 30 m.p.h.
A new American device is a tension gauge for estimating the tension load on flexible elements, such as cables, rods, wires, strips, etc. Small, compact and. efficient, it withstands a good deal of misuse, possesses no intricate mechanisms, and is built to yield a direct reading of the tension load of the member being examined. It can be employed by the ordinary mechanic or handy man without special training and without the necessity of using graphs, charts or conversion tables. Only 1 lb. in weight and low in cost, it may be used with one hand, and possesses additional interesting features.
Die-forged Crankshafts Automobile crankshafts are being successfully forged in dies in a 2,500ton press with a 14-in, stroke, operating at 50 strokes a minute. A German development is the " splitting " process of drop forging, in which a section suit:•!sle for drop forging is simply split from the billet of raw material, instead of the blank being drawn roughly to the shape of the die. By this method it is claimed that complicated forms can be built up with a reduction in the time spent on machining.
Hardening of steel bars from the rolling temperature in the mill is already being successfully carried out, and research is now being pursued to see if it be possible to temper in the mill, so that both hardened and tempered bars can be produced in a single-operation series. So far, from the economic point of view, the results appear to be favourable, the tests being carried out on bars of low-alloy chromium-vanadium steel. The impact strength of stock with a tensile strength of about 60 tons per sq. in. exceeded that of bars tempered in the normal manner. Tempering was carried out by induction heating.
Investigation of the best form of electrode tip for spot welding of mild steel, shows this to be a truncated cone with a base angle of 30 degrees. Chromium-copper electrodes have been found to last longer than those of cadmium copper.
Steels of virtually every type, including stainless steel, as well as certain non-ferrous metals and alloys, are being , successfully welded by the oxy-acetylene pressure method. In this, flat, clean surfaces are pressed together uhder a A 30
pressure of approximately 3,000 lb per sq. in., whilst a narrow region on each side of the joint is heated with multiflame torches to approximately 1250 degrees C. The metal is then upset to a regulated extent, thus forming an excellent weld.
A new process is designed to prepare the surface of cast iron, whether in the machined or non-machined condition, so that a good bond' is obtained in the later lead-tin alloy coating process. The casting is first dipped in an oxidizing bath, which converts the surface impurities to oxides. It is then immersed in a reducing bath maintained at 105 to 120 degrees C., so as to eliminate the oxide without exposing any additional graphite. This is succeeded by a rinsing in boiling water, and dipping for 15 to 60 seconds in 10 per cent, hydrochloric acid. A zinc ammonium chloride flux is applied to the surfaces to be coated. A lead-tin alloy containing only 5 per cent, of tin can be successfully applied after this treatment. A good lead coating for steel is obtained by hot dipping at 365-375 degrees C., the bath being covered with flux consisting of an 1-in, layer of zinc-ammonium chloride. The adhesion of the coating is improved if the lead contains 0.55 per cent. zinc.
A titanium-bearing steel has been introduced which is capable of being enamelled in a light colour without a ground coat, whilst still having an excellent finish. It also possesses good deepdrawing properties.
Supersonic Testing Device
Vital inspection by means of supersonic measurement is being made with the new Sonigauge, an instrument that measures the thickness of metal within the 0.02-in. to 0.4-in, range with an accuracy of 2 per cent, when only a single face of the metal is accessible. The instrument comprises a simple variable-frequency electronic oscillator connected to a quartz crystal. This is placed on the metal surface and applies high-frequency mechanical vibrations to it.
A new method of deep drawing oilsump pans has been developed. It is now possible to draw a 5i-in. deep pan in a single operation by improving the die design and the lubricants. An alloy suitable for facing castings or for weld rods for hard facing purposes contains about 1 to 4.5 per cent. carbon, 20 to 30 per cent, chromium, about 7 to 20 per cent. molybdenum, about 13 to 17 per cent. nickel, and about 10 to 30 per cent. cobalt. This alloy has a high rigidity at elevated temperatures.
An iron cement for repairing broken, cracked, or defective metal castings, making joints, seams and loose parts secure, and stopping leaks, has been developed. In powder form, it is mixed with water as used. No heat is needed. It can be applied with a putty knife or similar tool, and hammered into cracked or broken parts. After metallizing, it has the same thermal expansion and contraction properties as iron itself, so that it assures a permanently tight joint, irrespective of changes in temperature.
A new metallic flux with lower melting temperature than soft silver solder on initial heats has been introduced. When activated, it will work at temperatures rather higher than 60:40 solder, reducing distortion and material hardness and stresses.
Tubes Descale Themselves !
Another advance is a new selfdescaling tubing. This is constructed with a metal strip bonded to it from end to end, the thermal coefficient of this strip being lower than that of the tubing material, so that any accumulated scale is caused to crack when the tube expands under heat. The cracking of coatings in metallizing caused by expansion of the base metal during application is being overcome by a new device the syphon air blast. This comprises an aluminium ejector tube that can be mounted on a lathe carriage, bench or spray booth, and delivers 60 cubic ft. of air per minute with an air requirement of 4.5 c.f./min.
A simple method of colouring steel, copper, brass, bronze, zinc, nickel, tin, gold, silver, aluminium, magnesium and other metals and alloys through immersion in a chemical bath has been invented. A wide range of colours with iridescent or matte effects is obtainable.
A new fully automatic detecting device has been introduced in the United States for safeguarding the connecting rod and main bearings of an oil engine against wear or scaling. It comprises a a trip lever installed under each connecting-rod throw, a dump valve to be attached to the servo-motor of any standard hydraulic governor, a lug for each connecting-rod bearing cap, a control box containing • an air-pressure reducing valve and tell-tale light, and copper tubing for various connections.
A new electrolytic iron powder has an iron content of more than 99 per cent., the surface oxide being exceptionally low. This, combined with the general absence of impurities, makes it ideal for use in powder metallurgy and as an invaluable chemical reagent. It is available in any standard mesh from 8 to 325, and can be produced to any specified analysis. According to processing, its bulk density varies from 2 to 2.6 grams per cubic cm.
Designed for the repair of leaks in pipes, hose, or tanks from I in. to 30 ft. in diameter, a high-quality newly invented steel band of / in. width has a tensile strength of more than 2,300 lb. per sq. in. It can be applied with a 44--lb. tool, without shut-down or dis
connection. A new automatic tubeformer squares, burrs, flares and beads ferrous and non-ferrous-tubing of it in, to 3 ins, outside diameter with exact uniformity of finish. A new electric-arc torch provides a flame of 9,000 degrees F., for use with any a.c. or d.c. welder for 'welding, preheating, soldering, brazing or hard-surfacing.
A new phosphate-type finish for iron and steel provides unusual protection against rust, and is economical and simple to use. It is an ideal base for organic finishes, as the crystalline surface of the microscopically porous coat provides a practically chip-proof paint or lacquer finish.
New-type Coated Electrode A novel mineral-coated electrode is designed to prevent underbead cracking in the welding of high-tensile-steel plate, and has proved useful for welding high-carbon, cold-roiled and high.' sulphur steels. It has a less penetrating are than so-called hot rods, and produces a weld-metal of high tensile strength, equal in ductility and X-ray soundness to metal produced by downhand electrodes.
Cylinder life in internal-combustion engines is claimed to be increased from four to 20 times and piston ring life from three to four times as a result of coating with a porous chromium film. The chromium withstands corrosive acids produced from engine fuel during combustion. Moreover, it possesses the lowest coefficient of friction of any structural metal, is approximately as hard as natural ruby, and heat is conducted away through it 40 per cent. faster than through cast iron or steel. The porous structure prevents oil from running off; the pores, which are, in effect, tiny oil reservoir, are produced by reversing current at the last plating operation.
Tungsten welding electrodes containing 99.9 per cent, pure tungsten have been introduced. They are designed for use in hydrogen, helium and argon arc welding, and are particularly applicable to the rapid altering of dies. They are made in seven standard diameters of 12-in. lengths. A method of annealing stainless-steel exhaust manifolds to remove the stresses set up by welding has been developed.
A new method of evaluating surface roughness, involving the employment of quickly produced plastic replicas of variable transparency, has been developed, and tests indicate that this method is specially suitable for evaluating surfaces having a high degree of finish.
A new development is the steel piston-pin plug drawn from sheet steel and replacing plugs machined from solid aluminium rod, used in the ends of the piston pins of engines.
Gas pickling of metals is being more widely used, and has many characteris
tics making it highly adaptable to continuous processes. It does away with the need for disposing of waste pickling liquors.
A new swarf separator comprises a circular tank in which the effluent from the grinding machine flows across a sloping trough and thence down a tilted spout, which causes the liquid to make a circular motion and deposit the swarf on the outer perimeter of the tank.
Speedier Tube Cutting
The use of a plain wood V-shaped block, bound on the sides by a piece of canvas and topped off with a snap fastener, has greatly speeded up the multiple cutting of tubing. Important increases in tool life are being obtained, irrespective of the method in which refrigeration is employed by sub-zero treatment of high-speed steels followed by an adequate tempering treatment to relieve the tremendous internal stresses set up by the process. It is believed that refrigeration of — 100 degrees F. or lower is necessary to produce a marked change ill high-speed steel.
Increasing interest is being shown in the visnal examination of light metal casting using X-rays in combination with a fluorescent screen. Known as fluoroscopic inspection, this obviously rapid process is still technically inferior to radiography in sensitivity, but has already shown its usefulness for preselecting or sorting of castings tr radiographed. L.S.