The Iron Age 1937-07-01: Vol 140 Iss 1

CHILTON COMPANY (Incorporated) Chestnut and 56th Sts., Philadelphia, Pa. 239 West 39th Street, New York, 7 Owned and Published OFFICERS AND DIRECTORS FRITZ FRANK, Executive Vice-President FREDERIC STEVENS, Vice-President ERNEST WILLIAM BARBER, Treasurer JOHN BLAIR MOFFETT, Secretary JOHN H. VAN DEVENTER JULIAN CHASE THOMAS L. KANE CHARLES BAUR CARROLL BUZBY FAHRENDORF FRITZ FRANK President VAN DEVENTER Editor Managing Editor Editor Emeritus Machinery Editor Art Bditor Metallurgical Editor Associate Editors RICCIARDI OLIVER JURASCHEK Consulting Editor Washington Editor Resident District Editors Pittsburgh Chicago Cleveland Detroit Editorial Correspondents London, England Cincinnati FRAZAR Boston Hamburg, Germany Milwaukee San Francisco SANDERSON Asa JR. Toronto, Ontario Birmingham ALLISON Roy EDMONDS Newark, N. J. St. Louis TURNER Buffalo Editorial and Executive Offices 239 WEST 39TH STREET, NEW YORK, BAUR, General Advertising Manager DIX, Manager Reader Service Member, Audit Bureau Circulations Member, Associated Business Papers Indexed in the Industrial Arts Index. Published every Thursday. Subscrip- tion Price: United States and Pos- sessions, Mexico, Cuba, $6.00; Can- ada, $8.50; Foreign, $12.00 a year. Single copy, 25 cents. Cable Address, ““Tronage, N. Y.’’ ADVERTISING STAFF Emerson Findley, 621 Union Bldg., Cleveland B. L. Herman, Chilton Bldg., Chestnut & 56th Sts., Philadelphia, Pa. H. K. Hottenstein, 802 Otis Bidg., Chicago H. E. Leonard, 239 W. 39th St., New York Peirce Lewis, 7310 Woodward Ave., Detroit C. H. Ober, 239 W. 39th St., New York W. B. Robinson, 428 Park Bidg., Pittsburgh D C Warren, P. O. Box 81, Hartford, Conn. RON Contents 1937 Get the Roosevelts Mixed Honeycomb Metal Wing Features New Airplane Modern Vertical Core Ovens The Control Electrically Driven Machinery Bath Tubs Annealed Huge Furnace Climax Molybdenum's New Laboratory New Equipment Statistics Metal-Working Activity Rate Activity Capital Goods Automotive Industry Washington News NEWS Plant Expansion and Equipment Buying New Industrial Literature Products Advertised Index Advertisers Copyright 1937 Chilton Company (Inc.) 20—THE IRON AGE, July 1937 find scale, inside out! It's difficult tell just how clean pipe inside. Only service will tell scale was left in, and then too late avoid trouble. One way Bethlehem Pipe. During the making use two separate operations which remove virtually every flake scale, leaving Bethlehem Pipe clean, inside and out. STEEL COMPANY THE IRON AGE ... JULY 1937 Vol. 140, No. Get the Roosevelts Mixed HROUGH case mistaken identities, THE IRON AGE gave credit editorial published its June issue President Roosevelt for something that was said Col. Theodore Roosevelt, Jr. The quotation appeared editorial titled, Makes Strange and was from address delivered Elks convention which the massacre workers Illinois coal mine was condemned the following words: few weeks ago, southern atrocious massacre occurred contained our annals. Men were killed, not cleanly killed, but brutally killed, and the time which speak, there shadow conviction the murderers sight. blot this kind our escutcheon can wiped out but one manner and one manner only, and that due process law. are exist nation, must law-abiding. the law depends our society. Destroy law and the country reverts barbarism over night. Destroy law and will back the days slavery, rapine and pillage, when the strong oppress the weak, when interest triumphs overhonor. Without law, our civilization crumbles. Our government arranged such fashion that provides method whereby who compose can change were correct saying that the speech was delivered Assistant Secretary the Navy, but Theodore Roosevelt, Jr., was Assistant Secretary that time and not Franklin Roosevelt. apologize Col. Theodore Roosevelt, Jr., for having taken from him the credit for such clear-cut expression what must have been and still quite universal opinion. President Roosevelt must have been pleased our attributing that lan- guage him, for any man should proud have made such statement under the circumstances. ESTABLISHED 1855 | WILLIAM SHERMAN Detroit Editor, The Iron Age WORKING inside the limited space air- plane wing, Barkley- Grow Corp., Detroit, has fabricated all- metal honeycomb structure great strength and lightness support its new eight-passenger, bi-motored metal plane. Departures from conventional practice aircraft wing structural design have made possible great simplification stampings, riveting, assembly and finally putting the metal covering the wings. New rivet “squeezing” equipment devised and built take advantage this possibility easy and rapid construction. Because this new duction low cost and its in- vulnerability gun-fire and shrap- nel, has aroused the interest both commercial and military aviation groups. The first wing this type was designed Barkley, who entered aviation mechanic for the Wright brothers. More than year ago one these wings was built under contract for tests the Navy Department. After com- pletion these tests and successful tests before officials the Bureau Air Commerce, work was begun the first complete airplane. The craft, now the air, very prob- ably will shipped General Aviation Corp., Denmark, which planes Europe under license. comparison with other air- planes, especially other all-metal types, the Barkley-Grow plane interesting also because refine- ments the fuselage structure, unique one-piece construction which provides stiff union fuselage and wing, and improvement aero- dynamical performance through the combined use two types landing flaps airbrakes. The wing has neither conven- tional spars (beams) nor ribs (fore and aft formers). Instead tubes, cells, which provide the equivalent eight spars. The wing best described, therefore, aluminum alloy sheet coated each side with pure alumi- num guard against corrosion and maintain pleasing appearance. 22—THE IRON AGE, July 1937 Honeycomb Features New multi-spar cellular type with highly stressed metal covering, generally Construction consists the assem- bly number spanwise webs flanged for assembly purposes, and lightened means punched, flanged holes. Bottom and top covering, Alclad sheet*, riveted the internal structure. This arrangement produces uniform- tapered tubes cells extending outward the wing tip. Fully cantilever, this wing structure has supports outside the air- stream, all bending, drag and torque loads being carried the internal structure and metal covering. High cost aircraft, even with some degree quantity produc- tion all-metal types, has invar- iably been attributable great part difficulties encountered fabricating. many cases where the structure designed for the best possible strength-weight ratio, plans call for parts difficult form and assemble, often with tubular vide the equivalent Metal Wing ane rectangular tubes, eight spars. cells, plane the new type manu- factured Barkley- Grow Aircraft Detroit Eight-Passenger which require welding riveting almost inaccessible locations. Depending upon the size and kind, structure, the number joints made (welded, riveted fastened some other means) varies upward 75,000, according one estimate. thé Barkley wing design, ease stamping parts and assembling has been attained along with high overall strength-weight ratio for the structure. All parts can made with comparatively simple equipment—a low- production shops and boon for the high-output plant. Barkley-Grow factory, the north end the Detroit Municipal Air- port, webs and other similar parts are laid out templates, then stamped out with power press and flanged either power-driven hand-operated brakes. Rivet holes, center-punched the tem- plate, are drilled afterward. Then the metal webs are assembled stands ready for riveting. apparent from the accom- panying diagram that the honey- formation, even though is, anally, series closed sections, permits riveting the open because all flanges are bent outward. For this part riveting, therefore, the problem not one accessibility, but speed and good riveting the thin sheets. For assembling these flanged webs form the honey- comb, cross-handled air-driven riveter used. Two sizes rivet- ers are adapted this work, the largest, weighing being used near the root the wing panel where the section deep. easily handled the operator since suspended with counterweight from monorail and operated thumb control. One thousand rivets have been set with this equipment hr., min., average four rivets per minute. After the internal structure riveted and properly alined with stiffeners attached, the metal cov- ering put on. Here, appar- ent the photographs and the diagram, the problem rivet closed sections without bucking each rivet, slow and tedious proc- ess common this type work. Since the only possible direction travel for riveting machine this cellular wing spanwise (along the passageways between the webs), Barkley-Grow devised method and equipment accom- plish this. Eighteen-inch widths Alclad sheet are applied the wing chordwise (from front rear) the required spanwise traverse the riveter prac- tical value. This equipment consists large jaw-like frame which slides over the sheets riveted. the work end the jaws air- driven piston operates horizontally against rocker arm bellcrank which pushes down header, squeezing the rivet against seat. The mechanism can swiveled either side reach rivets not line with the center machine. This riveter weighs 125 and also suspended with counterweights from monorail. With it, one operator can set three rivets while two men with hammer and block drive and head single rivet. The jaws this riveter are made cast steel, heavy section and great strength being required avoid deflection when 1650 the force required upset the rivets, exerted 19% in. from the THE IRON AGE, July 1937—22 ‘ 4 4 the internal structure riveted and properly alined with stiffeners attached, the metal covering put on. | ersandringsare bulb section alumin- Hall Aluminum Co. chargers 5000 ft. altitude. The landing speed 62.3 m.p.h. with flaps operating. Through un- usual and exclusive combination split-type flaps, airbrakes, and slotted type, unusually quick takeoffs and rapid climb can ob- tained. This undoubted ad- vantage, now that many fields serving large cities are being re- classified and their use restricted slower planes which are capable clearing easily any obstruction the vicinity. the Barkley- Grow plane differential control makes possible operate the slotted flaps alone for take-off pur- poses, thus greatly improving take- off characteristics. intended that the Barkley-Grow type, with its 8-place seating arrangement, will used high-speed, high- frequency service for feeder lines from small cities large air- line terminals. also designed club plane for private owners executives corporations. easily adapt- able for military use. Design the new plane and tests have been directed Maier, former Army engi- neer. Commander Grow, concern and Mr. Barkley vice- president. THE IRON AGE, July 1937—25 q ] 1 back the jaws. Air pressure for the piston units varies from 100 but the rivet squeezer oper- ates set stroke, with the piston moving constant speed regard- less air pressure. The set-stroke operation insures against piercing rupturing the skin. Constant- speed squeezing gives the rivet ma- terial time yield and relieve itself strains, and this method avoids possibility metal fatigue from hammering. addition, has been shown that squeezed rivets not distort rivet holes, important factor working ~ for riveting opera- tion consists jaw-like frame which slides over the sheets riveted. Mechanism can swiv- eled either side reach rivets not line with center the machine. with thin aircraft material. The sheet used the wing varies thickness from 0.020 0.040 in. Barkley-Grow have patents pend- ing this special riveting equip- ment. The fuselage structure presents unique application extruded fuselage used. Thus the body honeycomb formation, this diagram shows, permits riveting the open because all flanges are bent outward. assembling the flanged webs form the honeycomb, cross- handled air riveter used. 24—THE IRON AGE, July 1937 the plane hollow tube, without internal support except for light stringers, fore and aft, and light rings intervals carry shearing loads. These serve also places for riveting the metal covering which actually carries most the stresses. All the stringers and rings are bulb section aluminum drawn the Hall Aluminum Co. This section has great strength and provides flanges for riveting. The arrangement simpler than using stringers and rings built from sheet stock angles and gives unobstructed interior, opposed the type fuselage which bulkheads are used carry shear loads. Wherever castings are required, the landing gear, tail wheel support and control system, mag- nesium alloy and aluminum alloy are used. The plane, which steam heated from the engine exhausts, pow- ered two supercharged Pratt Whitney Wasp, Jr., engines rated 450 hp. takeoff. Maximum speed 224 m.p.h., attained with super- WEB ‘ — EE oven, starting about ft. above the loading station and extending up- ward about hr. the cycle. Most the hot gases must pass through this section. Beyond one hour very little heat introduced the oven, the recirculated gases traveling upward around the head shaft and down into the heater which located about the height the top the cooling section the oven. The gas drawn into the heater, reheated, and passed back the oven, the gas flow being parallel the chain travel. Fig. diagram which shows the circulation cooling air and recirculated gas the oven. The heater semi-external, that radiant heat from the heat- escapes directly into the oven. The cooling section the oven comprises the last hour the cycle. Cool air drawn through the Explosion downtake shaft fan and dis- charged into the outside atmos- phere. This cooling air travels the opposite direction the chain travel and forced pass around the cores series baffles. Pro- visions are also made for passing cooling air across the trays during the last half the cooling cycle, when additional cooling required due heavier loading exceed- ingly warm weather. The cool air entering the cooling section keeps the discharge the oven cool. Fig. shows heating and cool- ing curve, one thermocouple being buried the center the core, the other being buried one-quarter inch from the surface the core. Chain Travel The travel the chain inter- mittent, thus permitting the trays stationary, and the same Temperature Safety Vents time level while being loaded. This also permits the very effective use baffles that they may lo- cated that point the oven where the trays come stop. 4-hour cycle the trays are sta- tionary for min. and sec. Fif- teen sec. are required for one tray move out the way and another move into loading position. The control the chain travel ob- tained limit switch actuated the trays and repeating electrical timer which can set for any de- sired cycle. The firing the oven done with two high-pressure inspirating type gas burners, using 1100 B.t.u. natural gas fuel. Control the gas the burners accomplished full floating valve, actuated potentiometer controller, the thermocouple from which the oven temperature con- Stack Coo showing the circu- lation cooling air Hand and recirculated gas Operated the oven. Dampers PLAN Auxiliary Cooling Air | RIGHT 2—Heating and cooling curves showing performance new oven. THE IRON AGE, July 1937—27 EE EEE | | | | | | 100 125 150 200 225 250 Time, minutes Modern Vertica ore Ovens MAUCH Foundry Engineer, Saginaw Malleable Division, General Motors Corp. DUE increased pro- duction and also the in- became necessary provide addi- tional core baking capacity. Be- cause limited floor space, and other good reasons, decided build either horizontal vertical oven. was also desirable design the oven for particular core which had sufficient tonnage keep the oven operating full capacity all times, yet have sufficiently flexible that other cores could baked should see fit. Some factors influencing the de- sign the oven were follows: desired bake and cool 320 differential housing cores per hour. These cores weigh about each and because they have large body and small diameter tube they are prone burn the tube section before the body baked; moreover, the sand used for making them has fineness number about 102, which makes the cores very difficult bake without cracking. that time these cores were being baked box-type batch ovens, and not our entire satisfaction. Preliminary experiments were 26—THE IRON AGE, July 1937 conducted determine the correct baking and cooling cycle, and was found that 3-hr. bake 400 deg. and 1-hr. cool would produce properly baked core which could handled without gloves. Inasmuch, sufficient tonnage could produced keep the oven full arranging core making equipment around the oven, was decided that vertical type oven would most desirable for our purpose. Oven Description The oven occupies floor space ft. ft. and extends ft. above and ft. below the floor level. That part the oven above the roof the building enclosed sheet metal penthouse. in. diameter head shaft supports two 120-in. pitch diameter sprockets, around which the chains holding the carriers travel. There are carriers the chains, carriers from the loading station the unloading station. These car- riers are located in. centers the chains order clear the head shaft. Each carrier contains two shelves which are in. apart, the shelves being in. wide and 100 in. long, capable holding differential housing cores. The con- struction the carriers makes pro- vision for the insertion addi- tional trays the event that the type cores baked this oven should change. Also the open construction the trays permits good circulation hot gases around the cores. The distance between the uptake and downtake ft. the clear, allowing ample room for the placing core benches both sides the loading station. The oven divided into two sections, heating and cool- ing, the heating section comprising three hours the chain travel, and the cooling section one hour the chain travel. The two compart- ments are separated baffle, however, the actual seal between the two sections obtained main- taining the correct static balance the oven. Any air drawn from the cooling section the oven into the heating section increases the spill, thus lowering the fuel efficiency, and also causes cracking the cores cooling too rapidly just be- low the baking temperature. Heated gases are introduced the oven through series ports arranged along the length the trolled being located the heating section slightly above the intake the combustion chamber. thermocouple located the delivery duct which actuates potentiometer controller, which turn actuates safety gas turn- down valve prevent the tempera- ture the hot gas delivered the oven from ever going any higher than desirable for good operating conditions. The temperature the oven held 400 deg. plus minus deg. Loading and Unloading Cores The cores are made roll-over core machines, one being located each corner the tray. Each oper- ator produces approximately cores per hour, and loads them his one-quarter the tray. The intermittent travel the chain permits the trays the most convenient loading position most the time. Suitable carrier guides are located the loading and un- loading stations prevent the car- riers from swaying. The cores are unloaded from the oven, inspected and sent directly the foundry for use. The core driers are left the trays and returned the coremakers the same se- quence which the cores are being produced. The oven fully protected with series the latest approved 28—THE IRON AGE, July 1937 safety devices prevent ex- plosion. Some the benefits derived from this new oven are follows: The fuel consumption about 600,000 B.t.u. per ton cores 1/3 lb. cores per cu. ft. gas which less than one-half that the batch type ovens. The heat storage the oven very low, the usual practice being start the oven one-half hour prior loading cores. This oven occupies 180 sq. ft. floor space and has capacity equivalent 4-4 compartment batch type ovens, occuping 1780 sq. ft. floor space. The baking the cores not dependent upon high heat head. This permits cores weighing one ounce baked with cores weigh- ing pounds without burn- ing off the small cores, and ac- complished producing very rapid circulation within the oven. result the rapid circulation the temperature the gases de- livered the oven about 430 deg. F., with oven temperature 400 deg. under maximum load condi- tions. addition producing very uniform baking conditions, this method heating also results marked core oil saving, inasmuch the maximum strength with the least amount core oil can ob- tained under these conditions. Much the gas usually prev- alent coreroom due the de- composition the core oil has been eliminated because the fact that the cores are taken from the oven cold. Production cores has been increased per cent over the old method with batch baking due the elimination waiting for racks, walking, poor turnover the equipment, rack changing, etc. The overall equipment turn- over cycle time has been from hr. This results considerable saving equip- ment, and also makes possible the much lower core in- ventory. cores due burning have been entirely eliminated, and breakage due trucking the green has been greatly reduced. The cracking cores due improper heating and cooling en- countered batch type oven has been materially improved. 10. Considerable trucking has been eliminated, inasmuch the coremakers load directly into the oven instead core racks, also the baked cores can sent directly the foundry used instead being trucked the cooling shed. 11. Less floor space needed for storage cores, the carriers the oven are utilized storage while the core room not oper- ating. | 3—Some the types cores being baked are shown this view the vertical oven. PART THE principal differ- ence between alternat- ing current contactors and direct current con- tactors the design the op- erating magnet. With a.c. current, the pull the contactor closing coil reverses direction each cycle, and each time that this re- versal occurs the flux passes through zero value, causing the contactor tend open. This tendency generally overcome The Control riven Machinery FRANCIS JURASCHEK Consulting Editor, The lron Age means additional short-cir- cuit shading coil, depending for its the main coil current, but out phase with the main coil flux about 120 degrees. Thus the time when the flux the zero value the main coil, the flux the auxiliary coil strong enough hold the contactor closed. Again, d.c. contactor coils have large number turns wire and hence high resistance; while a.c. coils have smaller number turns heavier wire, much bet- ter insulated. ° ° With d.c. coil the current the same whether the contactor open closed. The current a.c. coil, being determined the reac- tance the circuit, lower when the contactor open, because the air-gap the magnetic circuit. Consequently there will heavy inrush current the coil when the contactor first connected the supply line, some five ten times the normal value the cur- rent which will continue flow through the coil after the contactor has been definitely closed. The pilot device which handles the coil table in. hot strip mill, equipped with 237 squirrel cage motors, with speed adjustment frequency 4 7 THE IRON AGE, July 1937—29 AC. or D.C | Motor Driv ING Separate ABOVE IMPLIFIED dia- gram genera- tor-voltage method varying the speed direct current driving motors. RIGHT strip mill and two reels, each justable speed d.c. motor; with speed adjustments through generator voltage control. circuit must therefore designed pass this inrush current. Since the inrush current much higher than the normal current when the contactor closed, inadvisable interlock a.c. contac- tors, since anything happens prevent one contactor from closing, the coil the next contactor sequence will burn out. Likewise controlling a.c. contactors from remote point, this current inrush must considered selecting the size wire for the control circuit, that its resistance will less than that which would cause volt- age drop too great permit the contactor close. The contact mechanisms a.c. contactors are frequently immersed oil tank prevent arcing, heavy power circuits. Should the voltage high cause hazard used directly the push button master switches, the control circuit voltage may low- ered means control trans- former. Voltages higher than 550 are practically never used push button master controllers, and good practice keep control voltages lower than this, pos- 30—THE IRON AGE, July 1937 Control Relays. Shunt relays are similar a.c. contactors except that they are smaller and have lighter contacts. They may ar- ranged with various combinations normally open normally closed contacts, needed, and may equipped with magnetic blow- outs for protection the circuits, and with magnetic interlocks, just like the larger contactors. Series accelerating relays have three coils, connected the secondary circuit slip-ring motor, short-cir- cuit step resistance defi- nite value motor current. Magnetic Overload Relays auto- matically open two lines three- phase whenever overload causes cur- value. They may reset hand, may reset themselves automatic- ally when the overload conditions has been corrected. Phase Failure Relays are used prevent the operation a.c. motor one the phases has been reversed, disconnected the blowing fuse. Voltage Relays, arranged open close definite voltage value, are sometimes required for the protection the driven machine. Thermal Overload Relays were developed give better protection motors, with nicer discrimination the matter opening the cir- cuit than afforded magnetic overload relays, fuses, circuit- breakers. Many forms such re- lays are available, all depending = LARK-SUNDH a.c. Automatic across the line motor with externally operated disconnect switch, and over- load protection. Used for squirrel cage motors. Freld 2 titi SHEEN TO wine q | J the heating effect excessive cur- rent Special Speed Controls Frequency Change. The speed squirrel cage slip ring motor may controlled varying the RIGHT eight-foot American radial drill driven Westing- house shunt wound, constant speed d.c. motor. Operated push button controls. combined voltage and frequency the primary circuit. Both voltage and frequency must varied to- gether the same ratio; as, obtain half-speed, one-half voltage and one-half frequency (as com- pared normal) must supplied. The usual method doing this too expensive for general use, con- sisting the use alternating current generator driven vari- able speed direct current motor. One important and extensive use for this system for the speed control steel mill roll tables, where each roll driven in- dividual squirrel cage motor. All the motors are connected com- mon generator, the output which varied the d.c. motor driving it. The speed the entire table thus controlled varying the volt- age and frequency applied each squirrel cage motor the same time. (See illustration.) Cascade. Two induction motors are connected cascade when their shafts are rigidly coupled together and the secondary winding the first motor electrically connected the primary winding the sec- ond motor. When both motors tend rotate the same direction, they are direct cascade; when they LEFT auto- matic starter for constant speed shunt compound wound motors. Used for non- reversing service. Equipped with overload protection. tend rotate opposite direc- tions, they are differential cas- cade. The change from one effect the other made reversing one phase the secondary the first motor. One motor must the slip ring type; the other may squirrel cage slip ring. With two motors cascade, four econom- ical operating speeds are available. Either motor alone may con- nected the line, the two may connected direct differen- tial cascade. Kramer and Scherbius Systems. According Harwood (“Control Electric “There are several methods controlling the speed slip ring motor which involve the use auxiliary ma- chines. The general principle the introduction counter-voltage into the secondary the motor, which increases the slip any given load and speed. The slip energy, which lost with resis- = > * best tance control, saved these methods, being either returned the line electrical energy, con- verted mechanical power and ap- plied the shaft the motor. “The principal methods gen- eral use are known the Kramer system and the Scherbius system. The Kramer system essentially constant horsepower drive. THE IRON AGE, July ° ° ° | requires rotary converter, auxiliary direct current motor, and auxiliary alternating current motor. The Scherbius system constant torque drive, requiring three-phase compensated commuta- tor motor and auxiliary squirrel induction motor. third method, known the frequency converter system (see ‘frequency change’ above) may built for either constant torque constant hp. “Because the auxiliary ma- regenerative braking accom- plished with ease and effectiveness, (e) The system may easily made self-protecting against overloads means differential series field the generator, and (f) Its use, where its characteristics are suit- able, results increased out-turn with lower maintenance costs than possible with any other drive. The elementary scheme (which requires minor variations for par- ticular services) shown the accompanying diagram. motor- the generator exciter. For ex- ample, currents only one amperes may varied the field the generator exciter control 7000 hp. main motor. Two excellent brief accounts the application this general sys- tem d.c. motor control many industrial processes are contained the General Electric Co., and booklet adjustable speed motor drive published Reliance Elec- tric Engineering Co. times there are apt hp. Century duction motor drives this Carborundum saw granite mill through V-belts. Century hp. squirrel cage motor operates the saw car- riage. chines required for any these generator set required addi- =r = systems their cost too high permit their use small sizes. Their principal applications are main rolling-mill drives the steel industry, where the power may from 500 several thousand horse- power. The control equipment re- quire very complicated.” Special Speed Controls Generator-Voltage Control. Con- trol direct current motor speeds and direction rotation vary- ing the generator voltage and re- versing its polarity has extensive industrial applications today. Some the advantages this system may summarized follows: (a) Speed adjustment covers range from zero maximum motor speed, (b) The motor may almost in- stantly reversed without shock, (c) Speed adjustments and reversing are accomplished through manipu- lation field currents very low values compared with the arma- ture currents, (d) The application 32—THE IRON AGE, July 1937 tion the main motor, and sep- arate source direct current supply (which may exciter attached the motor-generator set other source constant- potential direct current avail- able). The main motor field excited from this constant-potential source. The field the generator excited similar manner, ex- cept that its circuit contains re- versing switch “S” and field rheo- stat The generator armature electrically connected the armature the main motor. Since the generator output may varied from zero maximum either polarity, the speed the driven motor will follow the voltage, and its direction rotation will agree with the polarity. This control accomplished through adjustments the relatively small generator field current smaller units, while very large units, found steel mill work, the same end accomplished varying the field misunderstandings concerning the functions motors capable delivering more than one constant speed. will well, therefore, review briefly the definitions such motors formulated the National Electric Manufacturers Association (NEMA): Adjustable-Speed ad- justable-speed motor motor which the speed can varied over considerable range, but when once adjusted, remains practically unaffected the load; such shunt motor with control, designed for considerable range speed adjustment. Varying-Speed ing-speed motor motor which the speed varies with the load, ordinarily decreasing the load increases; for example, series motor, compound motor, series-shunt motor. Adjustable Varying-Speed Motor —An adjustable varying-speed mo- tor motor which the speed can varied gradually over considerable range, but which the speed, when once adjusted given load, will vary consider- able degree with changes the load. Multi-Speed speed motor motor which can operated any one several definite speeds, each being prac- tically independent the load; for example, direct current motor with two armature windings, induction motor with primary winding capable various pole groupings. The difference between regulation” and “speed control” should observed. Speed regu- lation refers automatic variation the rate armature rotation caused change the load the motor. The term “good” used with “speed regulation” indicates that motor will maintain set speed within desired allowable limits under load fluctuations. With “close” speed regulation motor will hold set speed with slight change spite considerable load variations. Speed control refers the changing the rate armature rotation external means, such the insertion resistance the armature field circuit. The subject the control electrically driven machinery one which growing almost from day day. The foregoing discussions have been confined principally description the means available today for such control, with brief descriptions the more common applications these means. Later this series there will several articles specifically devoted un- usual control application methods, particularly steel mills and metal working shops. these fields advances are now being made great importance; tending more and more automatic opera- tion more less independent the judgment the human attendant. these methods and devices be- come perfected, get further and further into Machine Age which the unavoidable errors human operators are superseded the infallibility technical appar- atus which the process itself furnishes its own means accu- rate and economic control. Phosphorus Structural Steels the April meeting the Iron and Steel Institute (British), Jones, United Steel Com- panies, Ltd., reviewed detail the properties the normalised and annealed conditions large va- riety carbon and low-alloy steels with low and high phosphorus con- tents with the object assessing the relative values different com- positions meeting the require- ments the British standard specification for high-tensile struc- tural steels (37 tons per sq. in.) and conferring other char- acteristics which are desirable steel for structural purposes. The results, according Mr. Jones, confirm the generally accept- conclusion that the carbon con- tent must kept low high-phos- phorus steels and that the addition phosphorus alone low-carbon steel will not produce the adequate tensile strength association with other properties necessary struc- tural steels, e.g., absence far possible notch brittleness, low- temperature brittleness, strain-age- embrittlement and air tendency, together with improved resistance corrosion. The tensile strength low-carbon steel can- not raised above tons per sq. in. the addition phosphorus without market deterioration the notched-bar impact value. the presence other alloy elements, phosphorus behaves precisely the same manner plain carbon steels, but the phos- phorus content which undesir- able properties appear may raised. this respect, chromium exerts the most marked influence. For other reasons, the presence copper advantageous. With the restriction the car- bon content imposed high phos- phorus contents, Mr. Jones stated that the alloy content must high- than would otherwise neces- sary, and order obtain tensile strengths over tons per sq. in., high silicon content (the harden- ing effect which does not depend its association with carbon) must also present. such steel containing 0.15 per cent phosphorus, satisfactory notched- bar impact figure not retained when the tensile strength reaches tons per The application phosphorus steel must, therefore, remain strictly limited purposes for which the highest tensile properties are not required, and this limited field for lower- tensile material its use may re- garded permissible rather than preferable. The limitations are avoided the use normal phosphorus content. The carbon content then longer re- stricted, and comparatively low alloy additions tensile strength tons per sq. in. may easily obtained without introducing any risk the disadvantages which may accompany the presence high phosphorus content. was also stated that evi- dence has far been found in- dicate that high phosphorus con- tent confers the steel any useful increase resistance corrosion. Such effects were observed high- phosphorus steels were ac- counted for the simultaneous presence alloy elements. The first formal contract for ex- hibit space building con- structed the New York World’s Fair has been signed the West- inghouse Electric Mfg. Co. THE IRON AGE, July 1937—33 Briggs Steel Bath Tubs Annealed Huge Atmospheric Furnace RECENT step for- ward the manufac- ture enameled press- steel plumbing ware that division the Briggs Mfg. Co., Detroit, has been the installation what the only furnace its kind and probably the world’s largest continuous counterflow annealing furnace the controlled Brief descriptions Briggs tyware” bath tubs and other plumb- ing ware have been presented THE AGE from time time, the last mention being the ar- ticle, “Bath Tubs Promise Steel Outlets,” Nov. 26, 1936, but little has been said until now about 34—THE IRON AGE, July 1937 WYLIE Industrial Engineer, Briggs Mfg. Co., Detroit the press operations necessary for bath tubs drawn from single sheet thin gage metal. The material ingot iron 0.015 per cent carbon content and 0.078 in. gage. the first press operation the blanks, which measure in., are drawn full depth in. max. (not uni- form for entire length tub) huge “Clearing” press capable exerting 1500 ton pressure the platen. second drawing op- eration required turn over the edges the sheet, draw out the corners more nearly square and corrugate the bottom form safety tread. between the draws necessary anneal the tubs stress relieve them prevent destruction the metal the second draw. And incidentally, the tubs must washed free grease before the anneal. Obviously, the annealing such large semi-formed tubs with wide flanges presented mean problem, nor did subsequent pickling opera- tions required when ordinary box furnaces were used. fact, this was the first procedure employed, but one that proved most unsatis- |—The con- tinuous annealing oven for Briggs steel bath tubs large housed separately building which was erected after the fur- nace was place. factory. the first place, pro- duction was limited this method. meant taking out and putting one tub time. Besides, was extremely difficult control the annealing temperature know when the material had actu- ally that temperature. When cold tub was put the furnace, for example, the tempera- ture the tub itself would fail reach the empty closed furnace temperature much 200 deg. F., largely due convection and radiation losses necessarily large door was opened. Obviously, the stampings oxidized during the annealing and pickling had done hoist-operated immersion. The tubs are rather unwieldy for conveyor methods. Problem Solved Continuous Furnace The solution the whole prob- lem seemed continuous-type furnace the controlled atmos- phere type. Clean-annealing au- tomatically eliminated the trouble- some pickling operation, and conveyorization through solved the production limitation. But one had had any experience with continuous type furnace such size, much less one with atmosphere that was combustible. fact, number furnace man- ufacturers that were asked quote the job turned the general de- sign down being impractical and dangerous. They had visions result the infiltration air. 2—The stepped roof con- struction the incline permits the use oil sealed slabs give ready access for conveyor maintenance. The bottom the furnace clears the ground ft. and under housed con- veyor type washing machine and atmospheric gas manufacturing equipment. The Surface Combustion Corp., which installed the present equip- ment, was the only firm that had any real confidence from the start that the job could done, except the Briggs company itself. Its management was ready make the necessary investment equip- ment, confident that disaster would not follow, and actual experience proved conception right. one time during the experi- mental operation the furnace, for example, power was unavoid- ably cut off. The conveyor stopped and the exhaust fan the common entrance and exit vestibule ceased work, but the furnace obviously remained hot for some hours. Air filtered into the furnace atmos- phere, but explosion followed. seems that the air and gas mix- ture burned quietly within the furnace the hot zone. other explanation Furnace Housed Separate Building The photographs the furnace the process construction give fair idea its size. large arate building just outside the press shop the Briggs Mack Avenue (main) plant Detroit. frame work was erected before the building proper could around The large cross-sec- tional area was necessitated the fact that the work suspended hooks from overhead mono- rail and carried through broad- side. From inside wall inside wall the furnace measures ft., and from top bottom ft. in. order conserve heat and entrap the reducing atmosphere upward convection the heated gases, the furnace designed half-A type hairpin form with the heating zone the dead end. The material moves conveyor approximate 30-deg. angle, levels out horizontal position, enters the heating zone, turns around and goes down parallel incline common vestibule. Al- together there are 240 ft. con- veyor within the furnace. Each tub weighs 115 lb. and the cycle time hr. min. present, tubs 8050 material are charged per hour, although the furnace has capacity for double this. Propane Gas for Fuel Fuel for both the reducing at- mosphere and the heating pro- pane gas, which used for various purposes throughout the plant. This petroleum gas, which has heat content 2500 B.t.u. per cu. ft., lends itself particularly THE IRON AGE, July 1937—35 well the radiant tube element method firing. This method, de- veloped the Surface Combus- tion Corp., consists diffusion combustion burner within tube, which results uniform tem- perature over the entire tube. the same time the products combustion are confined and not come into contact with the work. this particular furnace tubes are U-shaped and are located the floors and the side and end walls. There also set ver- tical tubes the middle the furnace the end the hairpin. Altogether there are radiant tubes, varying length, but the same section—4 in. inside diameter the combustion sec- tion and in. the exhaust por- tion. Tubes are made high chrome-nickel heat-resisting steel. Gas pressure oz. per sq. in., air pressure oz. The products combustion are aspirated from the tubes under oz. vacuum and are fed cen- tral header which discharges into power washer located for con- venience under the furnace. Steam used for heating the water, ob- viously, whereas the exhaust gases make for heat losses. Direct gas burners are also provided needed cold weather. The washer employed degrease the tubs they come from the press room and before they are hung the 36—THE IRON AGE, July 1937 furnace conveyor. Furnace tem- peratures are controlled two Bristol potentiometer controllers, 1600 deg. being maintained the inlet the high temperature zone, and 1650 deg. the outlet. Only thin gage sheet metal wall separates the incoming and out- going work the incline and for about ft. the level portion the furnace. This permits heat interchange between incom- ing and outgoing work through radiation. matter fact, the work leaves the furnace practic- ally cold. this connection, interest- ing note that per cent less fuel required maintain the furnace temperature when the con- veyor loaded with tubs than when empty. The reason that so-called black body radiation becomes highly important when considered that full radiation down the furnace tunnel takes place over area 173 sq. ft., representing loss 34,600 B.t.u. per minute, equivalent 13.9 cu. ft. fuel. result this study, dummy sheets are hung the conveyor line during the pe- riod heating the furnace and these serve reflect the heat back into the hot zone. Insulation the furnace the preheating, heating zone consists Corundite ceiling slabs with in. top, in. and in. respec- tively N20 and Armstrong brick the side walls, and 12% in. similar brick the bottom. Surface Combustion type D-X machine supplies the reducing at- mosphere and the unit has ca- pacity 25,000 cu. ft. gas per hr., with pressure both air and propane. enters the furnace the partially burned gas has been cooled about deg. There are five distribution points through jets pipes the floor—three the level part the furnace and two down the 3—Semi- formed bath tubs entering and leaving the vestibule the Surface Combustion continuous annealing furnace. exhaust fan the hood pre- vents seepage toxic gas into the work room. incline. These last were added filtration air. typical an- alysis the gas within the fur- nace is: cent CO. 5.5 O, 0 “ce “ Circulating fans were provided first, but these were found unnecessary, owing the mix- ing effected the tubs the con- veyor line. first erected the furnace had entrance and exit doors, and some carbon monoxide got into the room appreciable proportions from certain amount diffusing outflow furnace atmosphere with carbon monoxide content high 10-12 per cent. Two things were done combat this toxic condition: the suggestion Briggs engineers, self-closing swing doors the bar-room type were added, and vestibule was constructed with exhaust hood and fan connection. The suction created exhausts any that might escape and also insures constant inflow air from the room into the vestibule, never the reverse. This exhaust fan now independent power line from the plant service, that its con- tinued operation assured. Insulation the conveyor from the furnace heat presented nice problem. The conveyor was built Mechanical Handling Systems and has all parts exposed the furnace made Hoskins metal (chrome-nickel alloy). I-beam monorails serve the supporting track and sectional alloy baffle plates are provided the hooks the point where they pass through slots the furnace roof. These plates slide along water- cooled base made hollow sec- tions welded plate. Altogether, 16-18,000 gal. hour plant sal- vage water pumped through this cooling system with the aid Wire Straightening and Cutting Machine Has Drive Haven, Conn., placing the market new “Dual Con- trol” Automatic Wire Straighten- ing and Cutting Machine, which takes wire from coil, straightens it, and cuts accurate lengths. the use two variable-speed units—ball bearing mounted and entirely-enclosed, high speed cut-off cam, and quick-acting clutch—is attributed the practical elimination marking swelling the wire, this being accomplished without the use intricate mechanism. The throughout. The variable-speed units provide infinite changes speed for the feed and cut-off and eliminate the necessity for stopping the machine for changing speeds. The two oper- ating handles are conveniently lo- cated the front the machine; one controls the feed and rough roll straightening units and the other operates the cut-off. The machine available number sizes. unit con- struction, the units comprising the preliminary straightening roll hous- ing, the feed roll unit, the rotary flier, the cut-off mechanism and variable speed units—all mounted welded steel base. The preliminary roll straightener removes the natural curve coil and rough straightens the wire be- fore the wire enters the standard five-die steel rotary flier which used for the finishing operation. The straightening dies can made hard iron, bronze, babbitt any other material suit the wire be- ing handled. The flier equipped with square-type straightening dies with patented guides between them, centrifugal booster pump. Lubri- cation the chain and plates mineral oil designed pri- marily for superheated steam ser- vice. Actual operating tempera- tures run around 400 deg. the seal. The photographs show stepped construction the incline portion the furnace. This necessary provide removable roof sections with oil seals facilitate maintenance the conveyor sys- tem, the same time giving gas- tight construction. which permit feeding the wire through the machine. The gear drive for the preliminary rough straightener and the feed roll units are entirely enclosed and run oil. Straightening flier, feed and straightening shafts are mounted Timken roller bearings and the drive shafts are mounted Norma Hoffmann ball bearings. Extension support brackets are new type. They are mounted steel pipe and are arranged that the cut lengths wire are held away from the machine and may thus removed readily with crane. The guide bar cover operated separate cam, independent the cut-off cam, and the guide bar itself stationary, being fastened the extension supports. The machine can furnished with front feed roll unit contain- ing single pair feed rolls, with double unit. Also, the vari- able-speed units may eliminated desired, make constant-speed machine. ‘ — a. ai straightening and cutting machine. With the variable- speed units, speeds may changed without stopping the machine. THE IRON AGE, July 1937—37 Climax Molybdenum Has REATLY expan