The Iron Age 1942-12-24: Vol 150 Iss 26

DECEMBER 24, 1942 THE DENISON ENGINE 1158 DUBLIN ROAD DEC 1942 Advantages are many Presses. Typical example the Denison line Press DLSC2 for straightening and countless assem- bling Exact tonnage for each task available without adjustments tonnage and stroke limits may set desired. control lever governs ram movement with pound-by-pound accuracy. Release control lever brings ram full daylight opening, pre-set, Fully self-contained with all working parts easily accessible. round-cornered and stream- lined for safety ample toe-room. Hand-lever foot-pedal control, both. 25, 50, 100 and 150-ton units. Write for Bulletin 109 ‘ COLUMBUS, OHIO — WIN! The and rush two new forwards... but teamwork good better than before. The who make replacements Whiting Victory Cranes are They keep production Victory Cranes roiling despite bottie- necks and shortages. WHITING a Smooth—quiet-running—durable experienced engineers, who ..these are standards that every Victory Crane Whiting Cranes have been measure its job. for nearly sixty years. They are the Corporation, 15601 Lathrop standards which every Whiting Harvey, Victory Crane built, despite restric- tions materials and construction. All changes, matter how in- operators, hookers-on, repair- consequential, must approved others. Copies request. New Handbook for crane operators \_ OFFICES CINCINNATI, DETROIT, LOS ANGELES, NEW YORK, PHILADELPHIA, PITTSBURGH, ST. LOUIS. AGENTS OTHER PRINCIPAL DECEMBER 24,1942 This Weekin... VAN DEVENTER President and Editor BAUR Vice-President and General Manager Editorial Managing Editor, LIPPERT Markets ROWAN the Scrap for Keeps Technical Editor, OLIVER Associate Editors Art Editor, WINTERS Editorial Assistants BUTZNER BARMASEL icles BENEDETTO BUTTERS Technical Artic Belt Life Shortened High Tension Washington Chicago tri Mills Cleveland Detroit Aircraft Rivets Headed How Choose Electroplating Carbide Tool Crib System Used Warner OSGOOD MURDOCK San Francisco Editorial Correspondents FRAZAR RAYMOND KAY New Equipment: Finishing Boston Los Angeles HUGH SHARP JOHN McCUNE Milwaukee Birmingham Toronto, St. Louis BACON Features Assembly Line DIX, Manager, Reader Service Washington ° ° ° West Coast Advertising Hottenstein, 1012 Otis Bldg., Chicago Dear Editor Raymond Kay, 2420 Ave., Los Angeles, Cal. Leonard, 100 East 42nd New York Peirce Lewis, 7310 Woodward Ave., Detroit Ober, 100 St., New York Fitzgerald 428 Park Bldg., Pittsburgh Warren, Box 81, Hartford, Conn. News and Markets Johnson, Market Research Hayes, Production Manager. Baur, Typography and Layout. This Industrial Week News Industry Personals and Obituaries Machine Tool Activity Non-Ferrous Metals Scrap Markets Iron and Steel Scrap Prices Comparison Prices Finished Steel Prices Warehouse Prices ° ° Member, Audit Bureau Circulations Member, Associated Business Papers Indexed the Industrial Arts Index. Pub- lished every Thursday. Subscription Price North America, South America and Possessions, $8; Foreign, $15 year. Single copy, 35 cents Cable Address ° ° Owned and Published CHILTON COMPANY (Incorporated) Executive Editorial and Offices Advertising Offices Chestnut and Sts. 100 East 42nd St. Philadelphia, Pa. New York, OFFICERS AND DIRECTORS Index Advertisers JOS. HILDRETH, Vice-President GEORGE GRIFFITHS, Vice-President EVERIT TERHUNE Vice-President BAUR, Vice-President WILLIAM BARBER, Treasurer JOHN BLAIR MOFFETT, Secretary JULIAN CHASE, THOMAS KANE, HARRY DUFFY CHARLES HEALE { \ 73 100 105 | i | IP AL pik — ALLOY FOR THE WAR MATERIEL BUILDERS strip and stacks sheet bars—Allegheny Ludlum Stain- less and Electrical steels—how well the United Nations will make use these vital alloys—and how well Hitler and the Axis would like have similar stockpiles great amount the United States enjoys. illustrated, these alloy steels are the hot-rolled state. still raw material. great deal careful and often highly involved processing—hot and cold-working, annealing, pickling finishing—must ready take their places the war lines. But one day soon —correct the exact physical, chemical electrical properties required them—these alloy steels will take their places the planes, tanks, guns and ships the fighting fronts. And always, most essential and important place. High-alloy steels are not ordinary materials. They are not produced, nor can they used, ordinary fashion. Above all, they must not wasted through faulty selection, undue scrap losses, too high per- centage rejects and spoilage, any other reason that would prevent fabricator from getting the maxi- mum amount war matériel from every ton alloy steels uses. both your and our re- sponsibility, and want help any way possible. Complete tech- 26—THE IRON AGE, December 24, 1942 nical and fabricating data avail- able all Allegheny Ludlum grades, and you need it, the per- sonal assistance our Technical Staff well. PITTSBURGH, PENNSYLVANIA | | . business papers America, representing every line special- ized industrial activity have enlisted for the duration. They have organized support the national drive for the recovery dormant industrial scrap the same manner that the newspapers America organized support the house house canvass for domestic scrap. Unlike the house house campaign, which had necessity dramatized “now operation, the collection dormant industrial scrap must week week, month month effort which will last for the duration. For long the war lasts, will have look our industries supplement from their non-used store equipment, the deficit scrap iron and steel needed keep our steel mills running maximum capacity. One thing should made plain the start. The accumulations domestic scrap which are now evidence some our towns and cities must not taken reason for the lack need industrial scrap. This domestic scrap serves most useful purpose. But its best use with admixture the higher grade heavy melting scrap which most industrial equipment composed. Steel mill efficiency increased mixing the two kinds together, and steel mill efficiency DECEMBER 24, 1942 what are after win this war. This business paper campaign, sponsored the industrial and business press America, will reach down into every potential source ESTABLISHED 1855 industrial scrap this country. will endeavor, through both editorial and advertising pages, impress upon each reader the vital necessity doing his part providing percent the steel needed beat the Axis. what means—50 percent. For every battleship, tank, shell and gun made this country one-half scrap. Scrap poor word for this precious material. For what call scrap, the steel industry, actually better, many instances than the virgin material. purer iron start with. This campaign the business and industrial papers America, both editorial and advertising will contribution the cause victory our publishers. The only rewards that hope from will the satisfaction doing needed job and the anticipation its help toward victory. But both these rewards are beyond price. The steel-producing industry, the metal working and fabricating industry have already done magnificent job this connection. our hope that may stimulate and help you even better one. industry indeed needs have success achieved along this line more than our own. 7 7 | | The doughboy stays his post come hell high water. knows his duty and does it. shirk that duty would mean defeat, even death—and disaster for all us. But cannot carry the fight alone. must have guns, ammunition, supplies. That our job! Unnecessary means lost ships, guns and shells —lost just surely they were destroyed our enemies battle. Stand our fighters—stay the job until the fight won! INLAND STEEL CO. DEARBORN ST., CHICAGO, ILL. Sales Offices: Milwaukee, Detroit, St. Paul, St. Louis, Kansas City 8, the important points which must considered the design gearing for aircraft engines the fact that, because the gears are light weight and the supporting struc- ture light and flexible, the effect elastic deflections under running loads must corrected. When multiple pinion planetary systems are used, Fig. some method pinions must employed. necessary hold the pinion bearing stud spacing +0.0005 in. and the normal pitch the gears +0.0002 in. The rims behind the teeth all the gears must flexible assist further with the equalizing action but carefully pro- portioned provide uniform bear- ing along the length the teeth. Fig. shows the type finish required for successful operation one the small pinion gears shown Fig. The root radius completely ground with surface roughness about micro-in. Finish the tooth flank about micro-in. r.m.s. Note that the sharp edges the ends the gear teeth are broken. This important order prevent fatigue failure from possible nicks the sharp edges. edge operation subsequent polishing must carefully and correctly performed order ac- complish its object. section through correctly hardened and ground pinion shown Fig. Note the heavy uniform case which runs from 0.035 in. with mini- mum surface hardness Rockwell and the full radius the roots the teeth. cross-section through incorrectly ground pin- anufacture ircraft Gears ° Wright Aeronautical Corp. engine gears are fragile and light con- struction, but are highly loaded. Balance load distribu- tion partly assured designed-in flexibility. Some the problems heat treatment and machining these gears within extremely close tolerances are discussed this article, which abstracted from paper recently presented before the American Gear Manufacturers Association. ion the type used the plane- tary reduction gear shown Fig. and demonstrates possible The radius the root the teeth has been ground deeply remove the hardened surface and properly blended with the flank one the teeth. Removal the hardened case this manner in- vites failure because the lowered endurance limit the material the surface the radius, which very highly stressed region. Improper blending the radius and flank invites failure because surface discontinuity. Tooth Modifications Necessary Design methods have been ar- rived over period time which permit build gear with rea- sonable certainty that can made work. Mathematically these methods are not complex be- cause the final answer obtained testing. Making gear set work generally involves modifications tooth form, supporting structure and gear tooth backing structure correct for elastic and tempera- ture deformations encountered service. These modifications are nearly always completed without increasing the weight and some cases are accomplished removing metal and thereby reducing weight. Some teeth, for example, require slight dropping off the involute the tip and others the flank. Some require both produce barrel type form. some cases necessary modify the pres- sure angle produce full bear- ing under operating conditions. has been well established that involute spur gear teeth the type commonly used aircraft engines can made work wide range pitch line velocities pressure the center the tooth contact area 135,000 per sq. in. the basis the Herz formula. (See Appendix.) Some well developed gears are op- erating excess this pressure. The range diametral pitch numbers commonly used from 12. this range would hardly attempt design gear THE IRON AGE, December 24, 1942—29 ° ° j ° ° ° | propeller reduction gear for deg. pressure angle and have face width 0.872 radial aircraft engine. the planetary type, in. The internal driving gear has 135 teeth and the consisting stationary central gear, small pinions carried the propeller shaft, and large in- ternal gear surrounding the pinions. The large internal gear driven crankshaft speed and the pinion carrying frame the propeller shaft 9/16 engine speed. The pinions the propeller shaft have teeth each 10.4 diametral pitch, with face width more than in. Some years ago, the stub tooth form was common use because its great static strength. How- ever, the trend definitely toward full depth teeth greater flexibility appears ad- vantageous the correction unavoidable deflections under op- erating conditions and the slight imperfections which are bound occur the machining process. further advantage the full depth tooth that the larger overlap permits more modification tooth form without destroying the rolling action. The thickness the supporting rim behind the teeth spur type gear can made approximately equal the thickness the teeth the roots. Modification the form and thickness the support- ing rim may necessary order produce proper tooth bearing. These modifications can deter- mined only after testing. The pin- ions used the planetary reduction shown Fig. were initially developed means photoelastic 30—THE IRON AGE, December 24, 1942 and brittle paint tests. Compara- tively slight modifications were necessary after engine testing. Spur Gears Favored With very few exceptions, all air- craft engine gears are the spur type. Helical gears have not found much favor aircraft engines. Should the ultimate quiet run- ning gears ever demanded, provisions will have made absorb end thrust, which the present objectionable feature. Her- ringbone gears many assembly problems and difficult handle because di- mensional changes the support caused temperature and deflec- tion. Spiral gears have not been used aircraft engines because they not stand under the high rubbing speeds with the lubricants available. noise not great importance because exhaust propeller noises far exceed gear noises intensity, and emphasis placed performance and reliability with minimum weight. However, sun stationary gear has 105 teeth. take-off power, each these pinions carries load hp. and each tooth operates under maximum contact pressure 120,000 per sq. in. The tangential load each tooth 372 The torque transmitted the propeller the complete gear 74,800 in.-lb. because the high speed which aircraft gears generally operate, the elements accuracy such involute form, normal pitch, and concentricity must closely main- tained. Distortion during heat treatment has been the greatest manufactur- ing problem facing the makers aircraft engine gears. Aircraft weight restrictions and compact design requirements result gear blanks such section and form that the least variation size, steel, furnace temperature steps processing produce warpage. Many experiments with heat-treat- ing methods and equipment did not completely eliminate distortion and was necessary find means correcting gear teeth after hard- ening. The most practical process available grinding. Approxi- mately per cent all aircraft engine gears are finish ground. Grinding Corrects Distortion Aeronautical Corp. was among the first use gear grinding high production method and has followed this pro- cedure closely since its inception. Both generating and formed wheel type grinders are used. believed that the overall cost com- pares favorably with that un- ground gears when all operations required produce similar gears other methods are considered. important that all operations prior finish grinding suffi- ciently accurate that substantially uniform stock removed the final operation. Grinding opera- tions must performed with care and skill avoid burning crack- ing the case. This done coolants, correct wheel speeds, selection the correct grade wheels, elimination side wheel grinding large areas and control case carbon content and hardness. Tooth form modifications are easily made with certain types grinders. Finish important considera- tion connection with highly loaded gears. All tooth surfaces must free from cutter wheel marks and blend with adjoining surfaces without sharp edges. particular advantage gear grind- ing the possibility refining the tooth finish the root fillet where the bending stresses are greatest. This especially true pinions where the cutters hobs produce generating ridges which 2—Type finish required insure service durability re- duction gear pin- ion. are the source possible tooth failure. important operation con- nection with the finishing many aircraft engine gears that breaking the edges the ends the teeth, mentioned connec- tion with Fig. The edges must broken and blended along the entire tooth profile well the root fillet. This involves consider- able bench work and for the pinion Fig. the standard time for cutting and grinding teeth 9.2 min. and that for burring and breaking edges 5.8 min. This indicates that per cent the time required produce the gear teeth consumed the hand op- 3—Section through correctly hardened and ground reduction gear pinion. eration breaking the edges. The break-edge operation done with pencil wheel thin disk special high speed motor head. For final finish and blending, the edge brushed with Tampico wheel polishing jack. cup type holder used prevent any surface but the edge from being brushed. There are some gears which can- not ground because their design and which require double set-up for roughing and finishing. The surfaces important gears this nature are finished lapping. Ground gears are lapped slightly remove the “fuzz” produced the grinding wheel. Both helical 4—Section through improperly ground pinion. Case hardened material has been removed the root. THE IRON AGE, December 24, ° ° 3 2 4 ‘ 7 = 4 é ae + 3 and internal type lapping machines are used. 100 Per Cent Inspection order minimize the possi- bility any defective gears get- ting into service, most aircraft engine gears are inspected 100 per cent. One the most important parts this inspection Magnaflux check. The in- dustry was one the first use inspection gear teeth. Minute flaws the material and grinding checks revealed this method resulted number re- jections when was first adopted but has led the improvement materials and processes that have today gears much superior those produced prior the general 32—THE IRON AGE, December 24, 1942 adoption Magnaflux inspection. check equipment and ma- chine set-ups, the involute form and normal pitch gear teeth are checked the final finishing opera- tion. many instances permanent records are kept determine the effect shop variations after defi- inspection, gear teeth are checked for size, surface finish, and for roll both adjustable and non-adjust- ABOVE IG. through plate type cam with driving gear and hub. The light sec- tions make this very difficult part heat treat. LEFT 6—Section through cam and gear showing small shaper cutter required because restricted clearances. able type fixtures. final check the gears and, fact, all aircraft engine parts the so-called “green run,” which running the completed engine from low load full speed and power. After this run, all parts are inspected for possible flaws be- involves approximately hr. fore final assembly, test ment. Nitrided Gears Nitralloy steel has several ad- vantages for production many aircraft engine gears. Today, about per cent the gears the en- gine are this material. One the important advantages tralloy that its use makes pos- sible surface hardening the teeth which would utterly impractical carburize and quench. The sur- face hardness does not drop after brief service frequently happens with carburized case. Our plane- tary gear systems are generally constructed with carburized pin- ion running between stationary gear and driving gear because the “sun” gear and surrounding gear are usually large and thin com- plicated section. There are some exceptions this practice where possible advisable for other reasons carburize two members the gear grain Fig. All gears are made from forgings with carefully controlled flow lines order secure maximum strength. has been well estab- lished that steel parts are some- what weaker under repeated load- ing and impact across the forging flow lines than the direction flow lines that gears made bar stock are not apt satis- factory. Forgings are normalized and annealed before machining. Gear blanks are usually finished grinding size before carburizing. Because the generally fragile and irregular sections aircraft engine gears, the major portion are quenched dies. very difficult part heat treat and finish the cam shown sec- tion Fig. Center bearing, cam track and gear concentric and The relation cam lobes and gear teeth must main- AF, ere i tained because engine timing requirements. Note the uneven distribution metal the web and rim parts and the cuplike shape which makes uniform quenching problem. The restricted cutter size necessary for forming the teeth shown Fig. Another example gear quite difficult heat treat satisfactorily that shown Fig. With this part the problem maintain the required concen- tricity between the internal splines and the gear teeth. Compare this gear with Fig. which shows section through automotive type transmission gear. Note its bulk and solid construc- tion. The mean value the maxi- mum contact pressure between the teeth the gear set which this gear part probably consid- erably lower during service opera- tion than the pressure most gears. The maximum pressure may higher but will exist for short periods only. Weight the gear not important. must not noise generator. The mean bending stress the teeth during service operation ably considerably lower than the similar figure for aircraft gears that full radius the tooth root particular advantage. The improvement effected this radius does not become great unless many high stress are applied given tooth service. For the same reason, finish the roots be- tween the teeth not particularly important. Many truck and bus gears are carburized and hardened SAE-3312 with ground spur teeth. Some pas- senger car gears are made SAE- 3312 and carburized but the major portion are deep out carburizing. Elimination the carburizing treatment tion with heavier results considerably less distortion. Core hardness higher than for air- craft gears. The majority automotive are finished shaving and the procedure shape hob the teeth with undercut tuberance type tool allowing ap- proximately 0.003 0.004 in. tooth thickness for shaving. The shaving tool finishes the working surface the tooth, the root and fillet remaining produced the shaper cutter hob. Most trans- mission gears are either solid shafts are the bulky propor- tions shown that they can solidly mounted during the machin- 7—Section through gear with splines. Such gear most difficult heat treat and finish satisfactorily. 8—The heavy sections automotive transmission gear present problem from the point view distortion heat treating. Fig. through aircraft engine gear that might shaved. ing operation. This rigidity tends eliminate error which might occur going from one operation another. are frequently asked why aircraft engine gear teeth are not shavetl. believe that gear grind- ing has many advantages con- nection with the type gearing must produce. Furthermore, before shaved gears can widely used aircraft engines, many de- tails manufacturing procedure will have worked out and the resulting gears proved engine test. Some the points which need clarification are: 1—If gears which cannot ground are shaved, will the undercut necessary clear the tip the shaving tool cause reduction load carrying ability? 2—Can distortion heat treat kept small enough permit shaving and can hardening sub- sequent shaving done with- out further distortion? 3—Will the cost controlling and inspecting preparatory opera- THE IRON AGE, December 24, 1942—33 | | ” 1g. 1g. ile ire ric in- tions exceed the possible time saved shaving? 4—Will existing furnace equipment and heat-treating methods pro- duce surfaces free from decarbu- rization view the hardness required withstand the loads? The demand for gear grinders the present war emergency necessitated the production ex- pansion program has made neces- sary seriously consider shaving all aircraft gears where there reasonable possibility success. This being done conjunction with various cooperative vendors and have doubt that many new and useful methods will spring from this work. example gear which could probably shaved shown Fig. This gear similar that Fig. with the important exception that there require- ment for close APPENDIX tween the teeth internal splines. Since these gears serve similar purposes, one obvious an- swer the problem shaving aircraft gears would redesign parts facilitate the process. This would tremendous job un- der any circumstance and impos- sible the moment. will, doubt, proceed over period time has the process rede- sign facilitate manufacture the automotive industry. The basic Herz formula was developed determine the maximum contact pressure between pair elastic rolling cylinders. One the things which can gotten from the formula the maximum contact pressure be- tween the two cylinders the center the contact area. This equation can modified applicable the surfaces pair gear teeth contact given below. sin PD, PD, Where Tangential load per inch tooth face a PD, PD, Pitch diameter pinion Modulus elasticity material Pressure angle Pitch diameter gear (external type) Maximum pressure center contact area The equation given the conventional one for com- pressive stress between the mating teeth two gears contaet the pitch line. The equation admittedly does not account for any stresses which may generated the gear teeth because the relative sliding action. Expe- rience has indicated that maximum pressure value 125,000 lb. per sq. in. can safely used for the initial design the supports for the gear system are properly constructed, teeth suitably modified account for deflec- tions and the gear have high strength core and case hardened teeth. Using the above formula and the maximum pressure value given, will found that deg. pressure angle in. pitch diameter pinion mesh- ing with in. pitch diameter gear with teeth conven- tional form can made carry tangential load 700 lb. per inch length there sufficient bending strength the teeth. find the Lewis formula satisfactory for calculation the bending strength gear teeth. One form this formula is: Safe load pounds per inch faee Strength core material. well known, the Lewis formula was developed the basis beam uniform strength which has the same bending strength the tooth its weakest sec- tion, which the root. The load was assumed act nor- mal the working surface the tooth the tip. For pitch diameter pinions bearing against large gears, find that the formula gives very good indi- cation the static strength the tooth when the ultimate strength the material. For repeated load- ing, which the normal case with gear teeth, modify the strength factor account for the reduction stress concentration the root the tooth accomplished use the full radius and substitute for the en- durance limit the material. Use the full radius in- creases the bending strength tooth approximately times that tooth with conventional root form. The critical stress most aviation engine gears tooth contact pressure and not bending stress. velocity correction factors have been found necessary any pitch line speeds have employed date. This probably true because gear rim sections are made flexible and tooth spacing accurately held. Belt Life Shortened High Tension ONCLUSIVE evidence that the life rubber transmission belting and V-belts greatly in- fluenced the tension factor, and that increase the tension over that recommended for the belt oper- ation will result failure the belt long before should break down furnished data from series tests conducted the Goodrich Co. Three grades the present war- time construction transmission belting were used series ac- celerated tests which were run per in. per ply, 720 lb. total for the tension, the recommended figure, and per in. per ply, total 864 tension, 4-in. pulleys. Belts were all in. wide, 34—THE IRON AGE, December 24, 1942 ft. length, spliced ft. endless lengths. Belt No. ran for hr. before breakdown while under the tension, and increased its life 230 hr. before failure when the tension was used. Belt No. ran for hr. the lb. tension, and for 263 hr. before failure Belt No. ran for hr. under tension, and the service life be- fore failure jumped hr. under the lb. tension. Conclusions reached are that increase lb. per in. per ply over the recommended tension results the belt giving only approximately one-third its useful service life. Similar conclusions were drawn from tests conducted one style V-belts used domestic washing machine. The accelerated test con- sisted dead load suspension with the driver sheave 25% in. out- side diameter and the driven sheave in. outside. First three belts under tension 125 lb. averaged hr. life before failure. Sec- ond three, under tension aver- aged 27.4 hr., while the last three, under averaged hr. giving these test results, the Goodrich Co. points out that because their short, highly accel- erated nature, they are not index life actual service, and were made only get data the ratio tension belt life. have any direct evaluation real service, tests should made for much longer periods, the report concludes. ; | i | HI | | European Adaptations Wide Strip Mills adaptation the contin- uous wide-strip mill developed America European con- ditions has been Europe and, according the Eng- lish Jron and Coal Trades Review, was the subject report the Rolling Mill Committee the Ver- ein Deutscher Eisenhuttenleute, re- printed Stahl und Eisen March 26. The report’s introductory re- marks point out that nearly all strip rolling processes wide strip first hot rolled from slab, and this product then cold rolled into continuous wide sheet. differ- entiate between these two opera- tions, the hot-rolled product des- ignated the report wide strip, and the mill producing hot wide strip mill, and the fin- ished cold rolled product called continuous wide sheet, and its mill cold wide sheet mill. These terms are used throughout the re- port these connotations. Considerations which taken into account, the article says, designing wide strip mill operate local conditions, include the tonnage and size the finished product; the balance between hot and cold rolling operations; initial cost; marginal products,which in- clude ranges just outside the or- iginal objective; the suitability the roughing finishing trains for individual jobs; roll diameter and barrel sizes; minimum and maxi- mum widths which can economi- cally rolled; general layout and composition, including number stands, intermediate heating ar- rangements, coil weights, and American development, and not feasible individual countries Europe because insufficient demand. German report devices for modifying continuous mills suit European conditions reviewed herein. stitching welding prior pick- ling. Before proceeding discussion the mill proper, the author fully considers the effect slab weights and the determination final gage and tolerances. The report then describes the characteristics various prototype designs mill and compares their capacities and practical efficiencies. The standard mill with which the various strip mill layouts are com- pared here the continuous wide- strip mill, the first prototype this type mill. The general lay- out this mill shown Fig. Its very high capacity is, course, offset the high first cost the mill, and although simpler layout may adopted, the cost does not drop direct proportion the re- duction capacity. addition the general dia- grammatic layout the mill, Fig. also includes diagram the rolling schedule, time diagram for fixing the slab sequence and hence the performance per unit time, and diagram showing the variations energy consumption. The short- est slab sequence the roughing train indicated the distance and the shortest strip sequence the finishing train the dis- tance This determines the maxi- mum capacity the mill, which according the final strip gage and the delivery speed, may amount 135 tons per hr. per in. strip width. This output per hour much lower than that which can calculated from Fig. Energy Consumption When the mill run capacity and there uniform strip se- quence, the peak energy consump- tion values are not much higher than the average consumption indicated the values and Similar conditions rule when roll- ing single strip, for which aver- age energy consumption cated The finishing stands are driven d.c. motors, and three-phase motors and flywheels stands. Intervals rolling each stand permit energy stored the flywheels. Nevertheless, condi- tions the last stand should carefully studied view the great length the strip has attained this point. some cases may prove practicable install more powerful three-phase motor with- out flywheel this stand. single stand through which the ma- terial reversed serves for rough- ing. This stand can either the THE IRON AGE, December 24, 1942—35 4 l- l- n- ce, es. Rolling program Finishing stands End coiler Roughing train Finishing stands stands two-high four-high reversing stand with “run-through” rolls. these mills, the rating the rough- ing train determines the capacity the mill. the train used the continuous mill—that is, six stands and scale breaker, shown Fig. 1—the output per hour the whole plant about per cent that the continuous mill. The coil weight, however, drops about per cent with the same rolling time per strip and same final strip gage. true the number stands re- duced three, but the cost the Furnaces Roughing stand Roughing stand Finishing stands matic layout continuous wide strip mill, rolling time and power con- sumption diagrams. electrical equipment, reversing program adopted, high. the stock enters the mill the remote side, the number passes the roughing train will odd, against even for the scheme shown Fig. therefore made, but the data are sufficient show that the substitution continuous roughing train single revers- ing stand does not bring any ad- vantage, largely owing the re- sulting reduction capacity. When selecting single stands, also for the finnishing train, should remembered that construction Finishing stands End coiler Semi-con- mill with two-high re- roughing Roughing stand and Finishing stands 36—THE IRON AGE, December 24, 1942 ishing stands and drive this stand must com- parable the stands the con- stand with three-phase drive chosen, the same three-phase drive that employed stand the continuous train cannot installed without alteration, since the rolling intervals reversing program are much shorter, and hence less time allowed for the flywheeds store energy. Quite apart from this, the number stands reduced and the number passes the roughing train cor- respondingly increased, the length strip the last pass will deter- mine the horsepower rating. medium width sheet mills early design, which may taken basis for comparison, 600 h.p. 700 h.p. per in. strip width sufficient with flywheel energy about four five times the stand- ard rating per cent reduction speed per second. compari- son, the required output motor strip mill must about 2000 h.p. 2500 h.p. per in. strip width, with correspondingly low- flywheel Use Existing Roughing Train existing train for roughing wide strip mill. the capacity this train low, may have very adverse effect the capacity semi-continuous mill the type shown Fig. and great care must taken incorporating existing train the. planned layout new strip mill. The installa- tion semi-continuous mill usually considered means reducing production costs, but due regard must also paid the re- duction output per hour and the lower coil weights obtained. re- ducing the coil weight, smaller number stands may used the finishing train, while retaining the same final gage sheet. the comparison made below, assumed before that the total rolling time the same the continuous mill; this signifies shorter slab, and hence shorter coil lengths, order make for the longer rolling stages conditioned other factors the mill. semi- continuous mill with two-high re- versing roughing stand and five fin- ishing stands shown Fig. already stated, the output per termined the capacity the roughing unit (distance A). Yet should noted that semi-contin- uous mills the roughing train Rolling-time diagram Power consumption ( ( \ ( | | Rolling-time diagram ° ° ° Power consumption driven the highest practicable speed, while the roughing train the continuous mill sufficient time available for the roughing passes. The coil weight this semi- continuous mill with five finishing stands about per cent that with the continuous mill, and the output about per cent. Energy consumption about two and three-quarter times the average value, disadvantage the semi-continuous type which has important bearing main course, obtained introducing flywheel. The rolling time the roughing train (A) much longer than the finishing train (B), and may seem feasible reduce the rolling speed the latter make the roll- ing times the same the two trains, and thus arrive uniform load throughout. Reducing the speed the finishing stands per cent will reduce the output per hour about per cent, and the coil weight around half, since, spite speed reduction, the total rolling time taken here basis comparison with the continuous strip mill cannot exceeded. When the strip reheated the course the rolling program, entirely different state affairs obtained. Various methods have been proposed for such intermedi- ate heating, but the present only the hot coiler has proved prac- tical. These furnaces serve less for reheating the material being rolled than for maintaining uniform temperature. The best known these hot coilers that used the Steckel mill. Germany plant these lines has been built, but cannot put into service under present conditions. Steckel Mill Fig. shows the same plant Fig. amplified hot coilers each side the finishing stand, con- verting the mill the Steckel type. heat losses are prevented the hot coiler, sufficient feed the strip into the coiler the proper temperature. this, the mate- rial its passage from slab coil- commences with gage about 0.5 0.6 in., and rolled down coiler thickness. The time taken this can here made longer than the total rolling time the continuous mill. Fig. the con- ditions are made nearly possi- ble the same those ruling the continuous mill, selecting the same weight and thickness slab Furnace Roughin Rolling program Roughing stand End coiler Finishing stand 3—Strip with stands only. Roughin Finishing stand and the same final gage Fig. Fig. also shows that the hourly capacity the mill determined that the finishing stand. Since the roughing stand not running capacity, thicker slab can ob- viously used the Steckel mill. Even ingot slabs from the point view thermal conservation can rolled down wide strip. The coil weight can taken great as, and even greater than, the continuous mill. the other hand, longer rolling time required the Steckel mill, that the output drops about per cent. The thinnest gage strip which can rolled the Steckel mill heavier than the final gage obtain- able the continuous mill, owing the distance the hot coilers from the rolls and the lower rolling speed, the maximum ft. per sec. being dictated reversing operations. The heavier final gage Roughing Finishing stand Roughing higher output, which cer- tain circumstances may rise much per cent that the continuous mill. Practical experi- ments alone will determine the final gages obtainable for different widths; these may roughly esti- mated 0.1 in. in. width and 0.08 in. in. width. Power con- sumption comparable that single-stand mills. The advantages the hot coilers are here offset the disadvantage that all finishing passes must carried out with the same pair rolls. This can, how- ever, overcome frequently changing the rolls, which may done min. min. per roll. Réchling Mill the Réchling mill, hot coilers are inserted between the stands the finishing train. The layout and principle this method have al- ready been described these col- mill. This the same plant that shown Fig. am- plified hot coilers each side the finishing stand. Finishing — = stands Power consumption THE IRON AGE, December 24, 1942—37 Rolling-time diagram Ix------ A-----.. { ) Power consumption y Rolling-time diagram Furnaces Roughing stand Finishing stands End coiler mill. this mill, hot coilers between Roughing the stands the finish- stand ing train. Finishing sta nds Roughing stand Finishing stands Power consumption umns, the general scheme being re- capitulated Fig. The strips leaving the roughing train are roll- the first pair rolls the finishing train and then coiled the following hot coiler. After few additional revolutions, the strip again uncoiled and passed through the second stand, this proc- ess being repeated the subse- quent stands. Again here, the Steckel mill, the material must have adequate temperature the first hot coiler. Owing the com- paratively high conservation heat, the number stands can reduced, and hence also the cost the plant. Fig. shows five finish- ing stands permit direct com- parison with the semi-continuous mill Fig. where again rough- ing done only one stand. scale breaker provided, and the degree reduction the indi- Furnaces Roughing stands Coiling Reversing Uncoiling Reversing vidual finishing stands correspondingly increased. this per cent that the continuous mill can obtained, although the output reduced about per cent. Contrary the semi-continu- aus mill, the capacity here not determined that the roughing train, but that the finishing train; nevertheless, rolling times the two trains should made the same far possible. reducing the number fin- ishing stands from five four, the operating data for this mill are modified follows: The capacity then about per cent, and the coil weight about per cent the cor- responding figures for the continu- ous mill. These figures can still further improved the last pass the roughing train made such that the fore end End ° ° ° Rolling program Roughin Finishing Stands Finishing stands 38—THE IRON AGE, December 24, 1942 1G. Semi-con- tinuous mill with hot coiler behind the first stand, five- stand finishing train. reaches the first finishing stand be- fore the other end leaves the rough- er. comparing this mill with the semi-continuous mill, due weight should given the higher coil weight and the reduction cost. introducing hot coilers the rolling train, various layouts may obtained; the principal these are shown Figs. and dis- advantage the continuous finish- ing train that the beginning the strip finished rolling few seconds, while the other end does not emerge for some time. Since the material being meanwhile, rolling conditions for the rear end are different from those ruling for the fore end, thus causing variations gage. seems reasonable, therefore, run the strip into hot coiler after leaves the roughing train, effect heat equalization and then pass the strip the finishing stands heat-stabilized condition. the finishing stands, the whole length strip then rolled under uni- form conditions, doing away with the disadvantage thermal in- equality. some strip after leav- ing the roughing stands cannot conveniently coiled owing thickness, the hot coiler should then placed after the first even the second stand the finish- ing train. Fig. hot coiler shown be- hind the first stand five-stand finishing train. The first finishing stand must run high speed commensurate with the rate de- livery from the roughing stand, and the strip then passed the second finishing stand speed lower than the continuous train, the speed through subsequent stands being also correspondingly reduced, well the delivery speed the end the train. This naturally reduces the output the finishing train, the introduction the hot coiler cutting down the delivery speed and increasing the total roll- ing time the finishing train. the fully continuous mill, the finishing train determines the ca- pacity the whole plant, the addi- tion hot coiler will reduce this figure, but this reduction cannot very large, since the overall utiliza- tion factor the continuous mill itself low. the other hand, hot coiler the semi-continuous lay- out permits the rolling time the roughing train more closely adapted that the finishing train, that here the overall ca- pacity not much reduced the hot coiler (Figs. and 6). heat as Rolling-time diagram m u = = a Rolling-time diagram Roughing Power consumption supplied the hot coiler, the coil weight can correspondingly in- creased and also the same high de- livery speed obtained con- tinuous mill can realized. not expensive add hot coiler, while offers the advantage in- suring uniform heat distribution. planning wide-strip mill, consideration must given number prerequisites and factors which are discussed some detail. Apart from the width the strip, the final gage required funda- mental importance fixing the di- mensions and layout such mill. Other important factors are the final coil weight and gage tolerances the strip. The variety prod- ucts which can rolled mill this kind permit the fullest utilization its capacity should also considered. comparison the various rolling schedules made Table showing the re- spective coil weights, capacity per hour and first cost the plant compared with continuous mill with six finishing stands taken standard. The data given this TABLE Comparison Various Systems Strip Rolling No. Type Mill Coil Weight PerHr. Cost Continuous mill with three roughers and six Semi-continuous mill with one rougher and six Semi-continuous mill with one rougher and Single stands, one rougher and one finisher. Steckel mill, one rougher and one 100 48.5 mill with five finishing stands and after each the first three finish- mill with four finishing stands and hot after each first and second finishers. 60-65 mill with five finishing stands and hot coiler after the first table are naturally only approxi- mate. selecting particular lay- out for strip mill, the closest Aircratt Rivets Headed Uniformly EPLACING human judgment automatic equipment the most logical solu- tion the problem maintaining high quality fabrication despite the influx new workers, particu- larly women, who can only develop sense mechanical values through long experience. One in- stance this situation comes connection with the driving rivets with small air tools the assembly aircraft fuselage sec- tions. Green operators tend over drive rivets and flatten the heads under drive and only par- tially head the aluminum rivet. they may proceed cautiously and waste time withdrawing the gun, after series blows, ob- the effect the head. ‘Time-Air” the name given new product developed the Mur- ray Corp. America, Detroit, for positively assuring the proper riv- eting time cycle. Attached the handle portable riveting gun, the device can controlled either automatically manually. lim- its the number blows delivered the plunger predetermined amount each time, tently producing rivet bucktails uniform height and diameter and avoiding re-hitting over-hitting, which requires drilling out and re- placement rivets. The device in- corporates air cut-off and bel- lows arrangement which assures uniform driving pressure until the last blow delivered the cycle. Time cycles are set turning small knurled head screw. Pressure can regulated for thin soft material turning another knurled screw. The standard trip-up cycle initiated fully depress- ing the trigger the device with the little finger while the regular gun trigger depressed with the index finger. When the operator pulls the trigger slightly back, the hammer operates long trigger held this position, thus permitting trim-up occasion- ally cycle. The Chicago Pneumatic Tool Co., New York, has purchased manufac- turing and selling rights the Murray Time-Air device and will place the market shortly. The design credited Murray re- search director Alfred Haberstump and his associates, Lowell Freeman, Alfred Comstock and Henry Polie. analysis necessary the basis the capacity and width strip required. the handle the air gun assures predetermined number blows drive each rivet. Close-up the de- vice (below), showing the auxiliary trigger for initiating the air timer. THE IRON AGE, December 24, 1942—39 l- its le- lly di- his pat How Choose Electroplating Equipment Much literature devoted the chemistry and metallurgy electroplating, but little known regard- ing the equipment available. Herein, the author com- pletes his analysis plating barrels, with data oblique barrels, contacts, anodes, etc. Last week, attention was given generalities regarding barrel construction and technique, and particular details horizontal barrels. two types. One the rubber steel cylinder solid wall type. These units are built either the single mul- tiple types. The cylinders have diamond button type con- tacts the bottom the cylinder which are connected star ring the inside the bar- rel. one type barrel only three the energized buttons are contact with the work and cur- rent while plating going or- der obviate any deposition metal the inactive buttons that get into the solutions. The other cylinder the perfo- barrels are made rated wall type bakelite rub- ‘ber, round hexagon shape, with pin disk type contacts. The solid-wall oblique barrel useful primarily for its flexibility and because its applicability very small parts which would pass through the perforations the horizontal barrel. Properly con- structed, rubber, composition 40—THE IRON AGE, December 24, 1942 ribbed, and easy clean. Thus, can used for variety solu- tions and after thorough cleaning, can changed over from some types plating others with com- paratively little inconvenience. Its capacity the “utility” sizes limited about lb. work. The maximum current carrying capacity this type oblique bar- rel about amp. Where larger output very small pieces re- quired, the practice add addi- tional oblique barrels the instal- lation. The most practical loads are from per cent the cubic contents. The perforated wall oblique cyl- inder greater ca- some cases. This type bar- rel has plating efficiency and yields uniformly plated product comparable the output the horizontal barrel. may have current capacity 100 amp. and used for building sub- stantial deposits (of copper, fo