US1496038A - Process of rolling steel rings - Google Patents

Description

June 3 1924. l 1,496,038

C. C. VENABLE PROCESS OF ROLLING STEEL RINGS original Filed Feb. 8, 1921 2 Sheets-Sheet` l JH Itozne we June 3, 1924. 1,496,038

C. C. VENABLE PROCESS4 OF ROLLING STEEL RINGS Original Filed Feb. a,l 1921 2 sheets-sneu 2 (g J/ J om@ C. UWM

@5&1 CHW/JU 9 M Patented .lune '3, 1924.

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CHARLES c. VENABLE, or WASHINGTON, DISTRICT. oF c oLUMBIA, ASSIGNOE BY Y HESNE ASSIGNMENTS, To THE WELDLESS EoLLEn liuNef COMPANY, A CORPORA- TION F OHIO.

PROCESS 0F ROLLING STEEL RINGS.

` Application mea February s, 1921, serial No". 443,367. neiiewed November 13,1923.

To all whom 'it may ooflwem:

Be it known that I, CHARLES C. VENABLE, a citizen of the United States, residing at the city of Washingtom District of Columbia, have invented certain new and useful Improvements in Processes of Rolling Steel Rings; and I do hereby declare the follow- A ling to be a full, clear, and exact description section have been rolled to a similar rectanof the same, reference being had to the accompanying drawings, formingvpart of this specification.

This invention relates to the manufacture of metal annular bodies or rings by the rolling of a cast. or forged blank of approximately the same weight as the finished ring but of relatively smaller diameter.

- The object \0f the present invention is to provide a process'whereby it is possible to roll small finished rings of irrgular shape.

from annuli. A further object of the invention is to provide a process, the use of which will eliminate the format-ion of annular grooves on the various faces of a rolled ring, such grooves or draws usually occurring on the wall faces of the ring.

A further object of the invention lies in the provision of a process in the practice of which each pressure point `on the top or bottom face of 'the biscuit vwill be in the. wall face of the corre.

same plane as'the Sponding reentrantA angle of the finished ring. fl'

It has long been knownthat metals whether vof uniform structure such as copas iron or steelv may' be greatly elongated by being passed -through a pair of driven rolls, the space between such rolls being less 'l than the thickness of the ingot or blank,l

outer roll formed as a separable mold and having the inner roll which is mounted on a movable axis, drive the plastic metal into the cavity in the larger roll, so that'when yper or aluminum or of fibrous structure such the annular body is completely formed, it will exactly fill@ the mold, but as far as I know no practical process has ever been 'known that would permit the rolling of an annular body of steel between a mandrel anda rollwhere the blank was free to expandv lengthwise of `the axis of the roller, although small-` rings of rectangular cross gular cross section with the formation on both wall faces ofdraws which are'elimivnated by machining the vvrolled ring to size,

the angle of pressure and the distance be tween the two rolls, which distance is commonly known as the pass The spreading may thus be keptlat a very low figure by having a relatively large pass and a low angle of pressure, annular rolling being par.- ticularly suitable tol small'side expansion as the langle of approach may be kept at a very low figure, say three degrees or less,

and the angle of pressure will be'correspondingly `low as it is a function of lthe angle of approach. A y

In rolling rings of copper or aluminum the metal has been found to flow so as -to take care of slight irregularities, but with fibrous materials such as iron and steel, the

strength of the metal is very different with the grain and transversely thereof, and for this reason it vhas been found practically impossible to successfully roll annularshapes of iron or steel,save where the finished shape was rectangular in cross section, yand even in this formationv a very considerable amount of metal is required to be machined off from the rolled ring. l

Inwiew of the enormous cost of labor at the present time, it has Abecome more an more desirable to forge steel blanks and to roll them out to finished shape for such in all of the reentrant angles to such extent that the cost of a rolled ring of this form isgreaterthan the cost of casting the piece and machining it, although it is true that a rolled ring machined down to proper size is materially better than a ring tained by casting. As far as l known however, Athe rolling of small steel rings of irregular shape has never been performed, except eaperimentally, and then only in the works of the company with which 1 am connected.

Careful study of the imperfections in the rolled rings indicates that in irregular shapes such as a flanged ring, the Harige being relatively small will cool considerably quicker during the rolling process than will the body of the blank, thus causing almost linvariably 'a draw on both wall faces of the flange, as well as a similar imperfection in the reentrant angle where the flange joins the body, the latter being caused1 by the drawing of metal from the heated body to the relatively cooler ange.

Other annular concavities or draws are formed elsewhere on the rolled ring, normally occurring on the wall faces of the body, probably due to the spreading of the metal on the inner or bottom face against the mandrel and on the outer or top face against the roll, each causing the metal to flow in a direction parallel to the axis of the rolls, that is, sideways of the cross section of the blank. During this action, the central strata of the metal between the two rolled faces is slipping backward in the direction of rotation of the rolls, while the'outer and inner faces are being pushed forward, thus causing a backward slippage of the central portion of the body due to the di'erence in length between the outer and inner faces, which as might be expected, causes end grooves or draws in each of the Wall faces of the rolled ring.

In order to clearly understand the process to bedescribed it is well to define the various term used in the art. The blanks are invariably annulanwith a central hole known as the bore which is the smallest diameter of the hole. The largest diameter of the blank taken as a whole is the overall diameter and half of the difference between the `overall diameter and the bore diameter is called the radial thickness of the blank. Any plane passing through the axis of the blank will cut the blank or biscuit forming a cross section known as a'projection wall section, the

incense greatest height vof which is the radial thickness and the dimension at right angles there.

to is known as the axial width of the blank. The outer faces of the blank are called the top faces to distinguish them from the inner or bottom faces which contact with the mandrel while the top faces contact with the movable roll. The side faces are called wall faces, that part of the wall face nearest to the top face being known as the outer wall face, while the one offset therefrom nearest to the axis of rolling is the inner wall face. .The side of the blank nearest to the rolling machinery isfknown as vthe rear right angles thereto in accordance with the usual meaning of the term. The draft is the anglel of relief formed on the side or wall and is measured in terms of degrees of inclination, usually 3, 5, or 7. The length of draft is measured along the longer leg of the angle considered as a right triangle and the depth is measured at right angles v thereto or along the shorter leg of such triangle. rlhe length of the draft is determined by the diameter-of the finished ring at that point and it increases proportionately with such diameter, that is the greater the amount of rolling required, the greater the length of the draft and consequently the greater the depth of the draft as well.

fn the drawings,-

'Figure 1 is a midsection of an annulus;

Fig. 2 is a similar view ofthe ring as rolled from the annulus illustrated in Fig. 1;

Fig. 3 is a midsection of an incorrectly formed blank; Fig. 4 is a midsection of the rolled section obtained from the blank of Fig. 3;.

Fig. 5 is a midsection of a correctly forme blank;

Fig. 6 is a midsection of a finished ring 'ready for machining into an internal ring gear;

Fig. 7 is la-'section of 'a forged ring blank; I

Fig. 8 is asimilar section of the rolled ring obtained therefrom and suitable for machining into a driving bevel gear; and

Fi 9 is a diagrammatic view ofI a setup ger rolling the ring shown in Fig. 6.

Fig. 10 is section of a blank for. rolling a ring of rec angular cross section.

A In Figure 1; is shown an annulus consistingl of a body 11 having auf outwardly extending flange'12, the latter having a top face 1,3 beveled at. a forging angle of 5,

while the body has a top face14 beveled at av somewhat greater angle. The bottom faces 15 and v16 are similarly beveled at angles of 5 and 7 but the side `or wall faces are left flat to correspond with the wall faces of the ring desired. Upon rolling this blank, however, the resulting ring, as shown infFigure 2, is found to be defective due to the deelldraws 20 and 21 formed at the' apex of t etwo reentrant dihedral angles and by the formation of the annular grooves 22 and 23 in the front and rear wall faces.

The faulty shape of the rolled ring is due to improper design of`the forged annulus. In the annulus the volume of the flange being considerably less than the volume of the body causes a higher percentage of heat reduction in the flange to that in the body, so that during the rolling process the flangein cooling first has its wall faces chilled, and then since the great mass of the body is stil/l hot, metal is drawn from the center of the relatively cool flange, thereby developingthe concave faces 20 and 23 on the 'flange and also the similar draw 21 at the junction of the flange and body. The draw 22 appears to be directl due to the spreading of the metal on the bottom face 16 and the top face 14 of the bod in a longitudinal direction causing a simu taneous backward slipping of the central portion of the body, due to the difference in the peripheral length of faces 14 and'16, this -condition not only forming the draw 22, but likewise contributing to the formation of the annular concavity 21.

In the experimental work in developing this invention, it was found that a considerable shortening of the flange, (see Fig. 3), a reduction to onethird its volume, 'and the relieving of the face C' D by a draft of 5 the entire distance from C to D', removed entirely the draw 20, since this reduction maintained the heat in the flange for a considerably longertime, and also allowed for the formation of the flange with a minimum contact with the upper roll. The draft angle 'bottom face H- G of the body is of 7 of face 15 which had previously been 7 was now changed to 20 which reduced'the contact in rolling, but was not sufficient relief to eliminate the draw of the metal at 721; but with an increase of draft (as shown in Fig. 5) in this counterbore to 45 the draw 21 4was entirely eliminated, and with the formation of a relief angle or draft'atthe corner B of 7 the finished ring was found to be perfect in all respects, the blank now having the form shown in,Figure 5, wherein the outer to face B-C is sloped at an angle of 5 whio is Othe present nor-mal drop forging top face practice; the inner top face D-E 1s provided with a draft of 7 owing to its coming first into contact with the top roll 30; the front inner wall of face F-Gr. is flat except for the reliefE-F of 7; the

`which is the usual drop forging practice;

the inner wall face K-H is flat, but the rea-r bottom face M-K is relieved to theextent of 45 which allows the rear wall face A-M to be flat.

Referringnow particularly to Figure 9l showing the set-up for rolling the internal gear shown in Fig. 6, the blank or annulus 31 is placed upon the mandrel 32 and is Y.

pushed rearwardly until the inner rear wall face H-K abuts the shoulder 33 of the mandrel at which time also the rear wall face A-M will be in contact with .the flange 34 which revolves with the mandrel and may be an integrall part thereof if so desired.

' The top roll30 is now lowered into contact rear outer wall of the body. 4It is quite essential that these conditions should obtain; that is, that the plane of the shoulder of the mandrel should correspond with the plane of the corresponding wall face of the finished ring and that'the plane of the-shoulder of the roll should correspond with the plane of the corresponding wall face of the finished ring. If this were not true, the

blank will be given a torsional strain which will create astress and consequent weakness in the rolled section. lt should be borne in mind, however, that where either the roll or the mandrel is rounded asis the case in Figure 9, that the point of the shoulder should be considered as the meeting point of the shoulder and periphery as if they met in a sharp angle.

The sleeve 37 is mounted to revolve'in a reciprocating carriage and during the rolling operation the carriage is moved towards the mandrel which enters a` recess in the sleeve with ,the latter in ver close proximity to, but not actually touc ing the outer side of the top zroll. As the top roll 1s brought nearer arid nearer to the mandrel the Acircumference of the blank is increased land the .rollingis continued until the blank, which is now the finished ring, 1s 1n contact.

with the three faces of the top roll, the four faces of the mandrel and the. single face o f the sleeve at which time the diameter of the ring will be the correct size since no draws are formed, due to the presence of the rehef angles. Without these drafts, draws would be formed no matter how great the pressure of the topv roll and sleeve and it-will be found that where these draws are present there will be'less area inthe cross section of the completed ring and'eonsequently when the top roll is lowered to its extreme point draft the diameter of the ring will be considerably l smoother, but as stated, in practice it is uunecessary for the reason-that an appreciable amount of machining is desirable, say a sixteenth of an inch and that if the inished blank were reduced to within a thirty-second or less of the ground size, the operation would be more expensive, due to the length of time it would take to secure the perfect set in the grinding machine.

Figure 7 shows a biscuit or blank correctly designed for rolling the rear axle drive gear shown in Figure 8. rlhe faces 43 and 44 are slightly beveled to permit rolling and the corresponding faces 45 and 46 of the blank preserve the' chosen angles. The faces 47, 48, 49 and 50 are exactly parallel tothe ground finished. faces of the gear and the corresponding faces in the blank 51, 52, 53 and 54 exactly correspond in direction to the faces of the nished ring. As will be noted from the dotted lines in Figure 7 representing the set-up, the top roll and the mandrel are both grooved to the Aproper shape of the finished ring and no side pieces such as the ange 34 and the sleeve 37 are required. There is no tendency for the metal to squeeze out between the mandrel and top roll where the faces are correctly beveled to the finished shape unless excess metal is present.

It' will `be understood that the annulus must contain the same weight of metal as the .iinished ring but when an annulus has been designed for any size ring or annulus 'the change to a different size lpresents no difficulty whatsoever since to roll a larger diameter ring, for example, from the blank of Fig. it is merely necessary to draw a cross section of the blank on a sheet of paper and divide such cross section by a line parallel to the axis of rolling, such a line being 41 of the ligure. Now by splitting the cross` section on this line and by'inserting a Macnee the volume 'of metal corresponding .to such area shall be'the required additional weight of metal a new cross section is formed which will be the accurate cross section of a blank which will roll the new size larger diameter ring. To roll a smaller size ring the same procedure is followed, but in this case after severing the cross section a rectangular area is removed such, for example, as that between the lines 41 and 42 of Fig. 7. By now joining the two remaining sections the new cross section is formed. lt will be noted that neither of these vtwo operations affects any of .the angles of the annulus since the wall faces of the added or subtracted area are flat, that is, they are normal or perpendicular to the axis of rolling.'

'What l claim is:

1. The art of eliminating draw in a rolled ring which consists in taking an annular blank having its wall faces relieved by the provision of drafts on each edge of said faces and rolling the blank circumferentially.

2. The art of eliminating draw in a rolled ring which consists in taking an annular blank having a body and a peripheral' flange with 'an obtuse Areentrant angle between the flange and the body and rollin said blank circumferentially. f

3. rlhe art of eliminating draw in a rolled ring which consists in taking an annular blank having a body and an outwardly extending peripheral flange with a reentrant angle between said flange and body, ,rendered obtuse by relieving the wall face forming one wall of said reentrant angle and rolling said blank circumferentially.

4.- The art of eliminating draw in a rolled ring which consists in taking a blank of smaller diameter than the size of the linished ring but of substantially equal weight, and having its outer and finner faces parallel to that desired for the finished faces ofv the-rolled ring and in rolling said blank ring. Y

CHARLES C. VENABLE.

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