US1018365A - Making carbon-steel car-wheels. - Google Patents

Description

UNITED STATES PATENT OFFICE.

WINFIELD S. POTTER, OF NEW YORK, N. Y.

MAKING CARBON-STEEL CAB-WHEELS.

No Drawing.

T 0 all whom it may concern.

Be it known that I, WINFIELD S. POTTER, a citizen of the United States, residing in the borough of Manhattan, city, county, and State of New York, have invented certain new and useful Improvements in Making Carbon-Steel Car-Wheels; and I do hereby declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same.

Thepurpose of my invention is to produce a carbon steel car wheel in a thor' oughly wrought condition throughout and of a uniform very fine-grained and suitably hard and dense structure, particularly in the flange and tread portions of the wheel, the manufacture being so conducted as to avoid in the preliminary and in the final forming operations, various laminations and other irregularities of structure in the steel which tend to cause breakage and irregular or rapid wear of the wheel in service.

In the usual procedure adopted for the manufacture of wrought carbon-steel car Wheels, the ingot or primary cast shape from which the manufacture is initiated is cast in the ordinary manner, so that usually blow holes, slag inclusions and other defects are present to a greater or less extent in the ingot after freezing.

In so far as I am aware, the manufacture of wrought steel car wheels has been heretofore so conducted that the steel is very coarsely re-grained by the use of very high temperatures prior to each portion ofjthe forming operation, and, in the forming operation itself, the steel is laminated by elongation, flattening, etc., of the coarse grains, and the elongation of any blow holes and other casting defects that are present, so that the resulting structure presents throughout its mass corresponding surfaces of greater or less extent which have relatively weak cohesion, one with the other. In the practice of my invention, I avoid these difficulties, myimproved wheel when brought to its final form and dimensions being substantially devoid of laminations and weak cleavage surfaces, and in a condition of great strength, the tread and flange portions particularly being in astate of maximum hardness consistent with the necessary toughness and shock-reslstance.

Specification of Letters Patent. Application filed December 16, 1911. Serial No. 666,237. Y

' may be employed.

Patented Feb. 20, 1912.

My improved wheel is, therefore, capable of enduring service longer than other steel wheels and with a more uniform wearing of its tread and flange portions.

In carrying out my invention, the carbon steel, while still molten, is suitably cleansed by reducing agents and by means of fluxes, and is held in the ladle prior to casting until the impurities have floated out of the metal. The ingot is then cast of a size to produce several Wheel blanks and may be of the usual tapered form. The'castingis so conducted as to avoid porosity in the main body portion of the ingot, that-is to say, in that portion which is to be cut up into wheel blanks. To this end, the metal is preferably poured into molds having tos which retain the steel longer molten in t e upper than in the lower ortion of the mold, so that the impurities of the steel accuinulate in that portion or part of the upper portion of the ingot which is to be rejected by cropping after the first stage of the forming operation. To this end, a mold having a suitable refractory top portion --Or the ingot may be with my U. S. Patent No. 967830, dated August 16', 1910. en the ingot has been cast, as above or in any other suitable manner to avoid porosity, it is permitted to freeze, and isthen stripped of the mold, while still hot, and is placed in the heating furnace or soaking pit. At the time of stripping the ingot, and when it is introduced into the soaking pit, it has frozen and cooled to a temperature in the average of about 1100 C. In the soaking pit, the ingot is equalized at a temperature between about 850 C. and 1250 0., but preferably between 1050 C. and 1150 C. to eliminate irregularities of composition occurring during freezing and cooling. Great care is to be exercised at this.juncture to avoid any coarse re-graining of the steel, and, to this end, after the ingot has been soaked within the temperature range referred to and has been equalized through cast in accordance out, it is withdrawn from the soaking pit,

for the reason that to retainit therein after the irregularities of composition have been removed tends to bring about the coarse regraining referred .to. So also, the retain: ing of the ingot within the soaking pit after the irregularities of composition have been removed has the further tendency to bring about, to a greater or less extent, an

operations,

but moderate duration, so

ases within the mass which correspondin y forces apart the crystals of the steel an thereby decreases their cohesion. When the ingot has been brought, in the soaking pit, to the desired condition and has been removed therefrom, it is reduced to parallel shape, 5. e. to a bloom of substantially uniform cross-section throu hout its length, and is then cut into wheel b anks of the required weight, preferably without heating it above 1150 C. For example, the bloom may be cut by one or more rotating cutting disks into suitable wheel blanks. Instead of cutting these blanks of a length and diameter ap roximating the ultimate diameter of the nis'hed wheel, I prefer, in the first instance, to roll or otherwise work the ingot, when bringing it to parallel form, down to a considerably lesser cross-section, so that in cutting oif a blank of the requisite weight therefrom, the blank will be correspondingly longer than the ultimate average thickness of the wheel. By this expedient, I am enabled to more accurately cut the ingot into blanks of the desired weight. The blank is then worked in its outer portions, for example, it is placed in a suitable die, closely fitting its margin and is then subjected to heavy pressure and is thoroughly worked in its outer portions particularly, the die being of such a character as to prevent any substantial amount of stretching in this tread portion. The purpose of this preliminary working of this outer or tread portion of the blank, while at the same time preventing elongation or stretching of said tread portion, is to avoid any such lamination in the finished product as would be due to internal flaws in the blank. That is to say, the thorough workin of the outer or tread portion of the evolution of blank at this stage of the operation has the effect of consolidating the metal in the tread portion and eliminating any possible internal flaws or cleavage surfaces therein. The blank is then removed from the die and reheated for further forming. By a suitable rolling or pressing operation the central part of the innermost portions of the blank are suitably worked to bring them into the desired wrought condition in so far as this can be accomplished in one heating, or during one or more re-heatings, and the blank as a whole is finally brought to the desired form throughout, either in a single operation or a plurality of pressing orrolling operations. During any of the reheating the re-heating is to be so conducted as to avoid any coarse re-graining of the steel after its initial working; moreover the re-heating operations should be of that neither the temperature of the re-heatin nor its duration shall have the effect of ringing about a feeble cohesion between the grains of the newest steel, particularly in the tread and flange portions of the blank. The standard practice, therefore, as just indicated, should preferably exclude a re-heating of the tread portions -of the blank at any time above 1150 C. or thereabout. If, however, the exigencies of the case require that, in order to suitably form the hub and web of the wheel, the entire blank should be reheated for a short time above 1150 C. (say 1200 C.), it will then be desirable to cool the tread portion of the blank, before submit ting it to any further forming -o eration, to a temperature below 650 0., an then to re-heatit for the next succeeding forming operation to the forming temperature (say 950 C. to 1150 C.), in order to suitably regrain the steel inthe tread portion before the tread portion is further worked.

The final working of the tread portion for the production of the greatest density and strength of metal should begin at an initial temperature throughout below 950 C. and is preferably finished at a tempera ture below 850 C. Thereafter, the tread and flange portions should not again be reheated to temperatures above 850 C. or thereabout. However, for the final working, the tread portion maybe heated toa temperature above 950 C. provided it is thoroughly worked at temperatures below 950 0. as the metal cools. At the termination of the final working, the finished wheel may be immediately cooled, as hereinafter described, or it may be placed in a furnace having a temperature range, for example from 750 to 850 C., but preferably about 800 (1., for a short time sufliciently to substantially equalize the temperature throughout the wheel, and the wheel is then taken from the furnace and subjected to a cooling and hardening operation.

The cooling and hardening operation may be carried out by first rapidly cooling from about 800 C. to below 550 C. (as for example, to 500 C.) equalizing the temperatures in the wheel at about 400 C. to 650 C. according to the hardness or temper desired and to remove strains, and then evenly and gradually cooling the wheel to atmospheric temperature. The rapid cooling may be carried out by immersing the entire wheel in any other suitable manner appropriate to rapidly extracting the greater partof the heat of the wheel. The re-heating of the wheel for equalizing the temperatures thereof at about 500 C. or 550 O. 'f the wheel has been cooled much below 500 C. is conducted in so gradual a manner and with such care as to avoid strains or cracks. Or, the rapid cooling of the wheel after it has been equalized at a temperature of about 800 C. may be executed'by supporting the wheel from its central opening on a shaft oil or in molten lead; or in by which it is rotated, and during this rotation, subjecting it continuously or intermittently to a shower of water until its temperature is reduced to from 400 0. to 650 0. in its various parts; whereupon its temperatures are e ualized and for ashort time held at 400 to 650 0. according to the composition of the steel and the hardness desired. The wheel is then gradually or slowly cooled to atmospheric temperature.

The tread and flange portions of the wheel may be given a.harder and stifier temper than the central portions, if desired, by cooling said tread and flange portions rapidl to a lower temperature than that to wh1c the central portions are cooled (as, for ex ample, by cooling the tread and flange portions to a temperature of about 400 0. and the central or hub and web p01 tions to about 650 0), and then partially equalizing the temperatures within the wheel by permitting a gradual flow of the heat from thehotter central portions to the peri hery of -the Wheel, until the tread and ange portions have received the desired temper heat. Thereupon the outward flow of heat from the central portions may be checked by the use of the water-spray or by rotating the wheel with its tread and flange in a bath of molten lead, or by any other suitable means of determining the extent of the reheating, and for finally cooling the tread and flange-portions, which should be gradually cooled to atmospheric temperature; from the temper heat.

By the designation carbon steel as used in this specification, I 'intend the steels knownto the trade by'that name, including such steels as contain moderate' quantities of other ingredients but not to such a degree as to change the laws concerning the crystallography and critical points of the steel greatly from the corresponding properties of pearlitic or carbon steels.

The expression wrought condition, here:

inafter used in the claims, denotes a state of the steel which results from a compression which may be accom anied by a molding of the metal while it as high temperatures, and which increases the cohesion between its so that the metal consists of grains smaller than before the pressure was applied and which smaller grains have one with the other an increased cohesion.

Having thus described my invention what I claim is: o Y

1. The method of making a carbon steel car wheel, which comprises casting the ingot so as to avoid porosity, and of a size to produce several wheel blanks; permitting the ingot, after freezing, to cool to a temperature not above 1150 0.; soaking the ingot at temperatures between 1050 C. and

1150 0. to eliminate irregularities of composition occurring during freezing and coolmg; reducing the ingot to substantially un1- form cross-section throu hout its length and cutting it vinto wheel lanks; thoroughly working the outer portion of the blank at temperatures between 1050 C. and 1200 0. and thereafter stretching the tread portion; forming the hub and web of the Wheel; reducin the tread portion throughout to a fine-grained dense condition by thoroughly .and finally working it at temperatures below 950 0.; cooling the tread portion durin such final working to below 850 0.; quickly cooling to below 550 0. after the final working; equalizing, to remove strains, at about 500 0.; and finally cooling evenly and gradually; substantially as described.

2. In the manufacture of carbon steel car wheels, the method of producing a blank in condition for subsequent Working, which comprises casting an ingot in such manner as to avoid porosity, and, after freezing, cooling the ingot to a temperature of about 1150 0.; soaking the ingot at temperatures between 1050 0. and 1150 0. to eliminate irregularities of composition occurring during freezing and cooling; reducing the ingot to a bloom of substantially equal cross section throughout its length and cutting it up into blanks; substantially as described.

3. In the manufacture of carbon steel car wheels, the method of avoiding such lamination in the tread portions as may be due to feeble cohesion between the grains thereof,'which comprises working said tread portions to form in oneor more working op- -erat1ons, each working operation of said tread portion being preceded by a heat of moderate duration at temperatures within ;the range of 950 0. to 1200 0.; substantially as described.

4. In the manufacture of carbon steel car wheels, the method of avoiding such lamination in the tread portionsas are due to the expansion of internal flaws therein,v =which comprises preliminarily working the :tread portion of the blank at temperatures within the'range of 1050 0. to 1200 0., and

thereafter stretching said tread portion; substantially as described. grains and which also crushes the grains,

5. In the manufacture of carbon steel car Ewheels, the method of avoiding such lamination in the tread portions as may be due 5 to internal flaws and as may be due to feeble cohesion between the grains, which comprises bringing the tread portion of the blank to a wrought condition prior to such ielongation. or stretching of said portion as would produce internal cleavage surfaces .therein, and then working and thereby stretching the tread portion in one or more working operations, each working operation being preceded by a heat 'ofmoderate duration at temperatures within the range of 950 C.'tO 1200 0.; substantially as described.

6. In the manufacture of carbon steel car wheels, the method of imparting a continuous fine-grained dense condition to the tread portion thereof, which comprises thoroughly working the tread portion of the blank at temperatures within the range of 1050 C. to 1200 (1.; then forming the hub and web portions; and finally working the tread portion throughout at temperatures below 950 (1., substantially as described.

7. In the manufacture of carbon steelcar wheels, the method of imparting a finegrained dense condition free from lamination to the tread portion thereof which comprises thoroughly working the tread portion of the blank at temperatures within the range of 1050'C. to 1200" (1.; then forming the hub and web -portions; finally working the tread portion throughout at temperatures below 950 C.; and cooling the treadportion during final working to below 850 C.; substantially as described.

8. In the manufacture of carbon steel car wheels, the method of imparting a finegrained dense condition to the tread portion thereof which comprises thoroughly working the tread portion of the blank at temperatures within the range of 1050 C. to

1200 G; then forming the hub and web portions; finally working the tread portion throughout at temperatures below 950 (1; cool ng the tread portion during final forming to below 850 (1; and thereafter quickly cooling to 550 (1; substantially as described.

9. In the manufacture of carbon steel oar Wheels, the method of imparting a finegrained dense condition to the tread portion thereof which comprises thoroughly work.- ing the tread portion of the blank at temperatures Within the range of 1050 C. to 1200 (1; then forming the hub and web portions; thoroughly working the tread portion at temperatures below 950 (3., cooling the tread portion during final forming to below 850 C.; thereafter quickly cooling to 550 C.; equalizing at about 500 (1; and then cooling evenly and gradually; substantially as described.

10. In the manufacture of carbon steel car Wheels, the method of forming the tread portion, which comprises preliminarilyworking the'tread portion of the blank at temperatures within the range of 1050 C. to 1200 C., further forming and thereby stretching said tread portion, and thereafter reducing the tread portion throughout to a fine-grained dense condition by thoroughly working it at temperatures below "950 C.; substantially as described.

11. In the manufacture of carbon steel car workingit at temperatures below 950 (1.;

and cooling the tread portion during final working to a temperature below 850 0.; substantially as described. 7

12. The method of making carbon steel car wheels, which comprises producing an ingot substantiall devoid of porosity, and from which the lrregularities of composition occurring during freezing and cooling have been eliminated; cutting the ingot into blanks; preliminarily working the tread portion of the blanks at temperatures within the range of 1050 C. to 1200 (1, forming and thereby stretching said tread portion; forming the hub and web of the wheel; and finally reducing the tread portion to a fine-grained dense condition by working it at temperatures below 950 (3.; substantially as described. 13. The method of making carbon steel car wheels, having a continuous and fine- Y grained and tempered tread portion, which comprises preliminarily reducing the tread portion of the blank to a wrought condition prior to any considerable elongation or stretching of said tread portion; completing the forming and thereby stretching the tread portion in one or more working opera tions at temperatures below 1150 (3., each working operation-being preceded by a heat of moderate duration at temperatures within the range of 950 C. to 1200 C; equalizing at a temperature between 7 50 C. and 850 C.; rapidly cooling the tread portion and bringing its various parts to the desired temper heats; and finally'gradually cooling from the temper heats, thereby obtaining a graduated temper in the tread portion of the wheel; substantially as described.

. 14. In the manufacture of carbon steel car wheels, the method of re-graining the tread portion of the blank in those instances where said tread portion during the forming of the hub and web has been re-heated to above 1150 (l, which comprises rapidly cooling the tread portion to about 650C. and then re-heating it at the temperature necessary for its further formation; sub stantially as described.

In testimony whereof I afiix my signature, in presence of two witnesses.

WINFIELD S. POTTER. Witnesses:

M. A. BILL, MINERVA LoBnL.