US1077014A - Process and apparatus for piercing and rolling tubes. - Google Patents

Description

R. 0. STIEPEL. PROCESS AND APPARATUS FOR PIERGING AND ROLLING TUBES APPLICATION FILED JULY 3, 1912.

Patented 0013.28, 1913.

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RALPH CHARLES STIEFEL, or ELLWOOD CITY, PENNSYLVANIA.

PROCESS AND APPARATUS FOR PIERCING AND ROLLING TUBES.

To all whom it may concern Be it known that I, RALPH CHARLES STIEFEL, of Ellwood City, Pennsylvania, have invented certain new and useful Improvements in Processes and Apparatus for Piercing and Rolling Tubes, of which the following is a specification, accompanied by drawings.

The invention relates particularly to piercing solid steel and other billets in the heated state and rolling them out into tubes by means of cross rolling bodies and a mandrel bar.

The prime object of the inventionis to ac-' complish the piercing and rolling out of the heated billet in a single continuous and progressive operation with least loss of time consistent with a proper action upon the billet, thereby preventing such loss of heat of the, metal as would result in injury and commercially satisfactory way of making tubes from iron or steel billets by a continuous operation, itis the customary, and probably most approved, practice to first pierce the solid billet in a piercing mill, and then remove the pierced billet to a rolling mill,

and there roll out andelongate the'tube and reduce its wall thickness as required. In this practice a loss of time occurs when no actual work is beingperfornied on the billet, and considerable cooling of the metal inevitably occurs. Either reheating of the billet is necessary before the completion of the rolling operation, or else the cooling of the metal results in great wear and tear in 40 tools and machinery, the expenditure of ex cessive power and the production of undue and injurious strains in the metal of the billet and in the finishing rolls. Additional treatment, such as annealing, may become. necessary by reason of such strains in the billet.

The present invention provides for the piercing of the billet and cross rolling of the tube continuously and progressively in ing sets of "pairs of cross rollin bodies, the forces applied to the metal being such that the tubeis satisfactorily and rapidly formed without undue strains or undue ,wear and tear on. the 5 apparatus employed. I

Specification of Letters Patent.

Patented Oct. 28, 1913.

Application filed m a, 1912. Serial No. 707,502.

The invention will be readily understood from the following'description, and certain other features not heretofore mentioned will be apparent therefrom.

In the drawings, Figure 1 is a diagrammatic longitudinal sectional plan view of one preferred arrangement of rolling bodies and mandrel bar for carrying out the improved process without expansion of the tube; Fig. 2 is a side elevation of the same arrangement; Fig. 3 is a view similar to Fig. 1, showing the arrangement where expansion as well as elongation of the tube is desired.

The housings, bearings, guides, driving connections, 'etc., which can manifestly be added in a great variety of forms without affecting the invention, are omitted,- as in many of the-patents in this art, for the sake of clearness of presentation.

' The terms billet and tube are employed in this specification to a large extent interchangeably; and by the term roll pair or pair of rolls I do not mean to exclude groups of three or more rolls set around and actin upon the same cross section of the billet in place of two oppositely acting rolls. I r

In Figs. land 2, four pairs of overlapped disk-shaped rolls are shown acting pro-gres sively, and 'to a large extent simultaneously,

upon the billet or tube. The longitudinal or feeding component of the cross rolling motion is produced by raising the "axes of the rolls which arehorizontal somewhat above the plane of the axis of the pass, which is horizontal. The succeeding pairsof rolls have their axes raised progressively, so as to give progressively increasing longitudinal feeding action. The rolls are shown slightly inclined from the ass, asv seen in the plan view, to allow su cient clearance between the billet and the inactive side of each roll.

It will be understood that other-shapes and arrangements of roll pairs may be used to give the same'cross rolling and longitudinal feeding components of motion as the rolls shown. The formv selected. for illustration is that which I prefer.

In Fig.1, the axes of the rolls are shown in full, but the rolls are ea ch s ect ioned, as follows: At the portion in contact with the billet, the roll is sectioned in the plane of the axis of the pass, as atthe lin 15-6 of roll is sectioned on the plane of the axis of the roll, as shown by the line 34 of Fig. 2. The section is, thefefore, taken on the line 34c5-6. The rolls B, C, D, E, F, G and H are similarly sectioned. The arrows in Fig. 2 show the direction of rotation of the rolls and the tube. The circles drawn in dash and dotlines correspond approximately with the path of mot-ion of the center of the contact surface of the roll against the billet.

At J is shown the mandrel bar lying along the axis jj of the pass and provided with a point M. The mandrel is supported against end thrust, but is free to turn against a suitable abutment L, and is of such length that the tube may pass clear from the last pair of rolls without striking the abutment.

The billet is first pierced under the cross rolling pressure of the rolls A and B, which for this purpose, as will be Well understood,

should have faces which converge and then diverge in the longitudinal plane of the pass, as is illustrated in Fig. 1. Also, as will be understood, the mandrel point should be in serted between the rolls and sustained at approximately the position shown. Under the cross rolling pressure of the rolls A and B, the billet is plerced and forced over the point of the mandrel bar, and as soon as its forward end reaches the second pair of rolls C, D, it is by them subjected to cross rolling pressure upon the mandrel bar and the wall thickness reduced. These rolls have rollin faces which are convex in the longitudmal plane of the pass and of such restricted extent lengthwise of the pass that they act to thin the wall and elongate the tube upon the mandrel bar, being aided in so doing by the fact that their component of feeding motion is reater than the preceding roll pair, so that t ey tend to feed the metal of the tube more rapidly forward.

By the term convex I do not mean to exclude the angular form, as shown in the rolls A and B, but I prefer the continuous curves illustrated.

As the billet still further progresses and reaches the third pair of rolls E, F, it is there subjected to cross rolling under convex surfaces, preferably with an increased component of longitudinal rolling movement or feed, in excess of that commensuratewith reduction of the cross sectional area of the tube, so that the tube is subjected to some longitudinal tension in the interval preceding these rolls. Preferably, also, the convexity of the rolls E, F, is somewhat less than the convexity of the rolls G, D, thereby mak ing less of a noticeable spiral depression or groove in the outer surface of the tube. At-

rounded oii' margins of their working faces,

preceding them and following the rolls E, F.

It is desirable that the successive pairs of rolls be approached closely to each other for several reasons, thereby decreasing the time and space intervals between the succeeding actions, and also increasing the duration of the simultaneous operation of adjacent pairs of rolls.

It will be seen that the piercing action is almost immediately followed by a progressive, and to a large extent simultaneous, cross rolling treatment of the billet in a plurality of succeeding roll pairs in a manner to elongate and thin the tube, and subsequently, and to a large extent simultaneously, the tube is subjected to continuous smoothing action. This last action also insures a slight looseness of the tube upon the mandrel bar, so that it may be readily re moved therefrom after it leaves the last roll air.

Manifestly, the number of pairs of convex elongating rolls, such as C, D, and E, F, which it is desirable to employ, will depend .upon the degree of elongation and reduction of wall thickness desired. Where the convexity of the last pair of these rolls is not very pronounced, one pairof smoothing rolls G, H, is sufiicient to substantially smooth and finish the tube.

It will be understood that the interval between the two rolls of a pair which determines the width of the pass and the consequent reduction of the external diameter of the tube by such pair will be diminished slightly in the succeeding pairs of rolls from C, D to G, H, the degree to which it is advisable to. reduce the wall thickness in a single pair of rolls depending, as the skilled operator will know, upon the temperature and also upon the toughness and quality of the metal undergoing treatment. The longitudinal tension produced by the disproportionate or excessive increase of the feed component, as explained, may be much lessened or entirely absent where expansion in the diameter, as well as elongation of the tube is desired or permissible. v

The continuous process of progressively and simultaneously piercing, elongating and expanding the billet and reducing the wall thickness of the tube is illustrated in Fig. 3.

Preferably the rolls C, D,-E' and F will be somewhat fiatteuand less convex than where there is, to be no expansion, and the longitudinal tension produced by disproportionate increase of the feeding component of succeeding roll pairs-may be much diminished ascompared with Figs. 1 and 2, or may be absent. The mandrel bar P should have successively enlarged cylindrical portions Q and R of diameter to approximately fill out and fit the expanded interior of the tube after it leaves the preceding pair of rolls as illustrated. In this expanding process, separation of the rolls of each pair will progressively increase to correspond with the increased external diameter of'the tube, allowing, however, for sufiicient rolling pressure upon and reduction of the metal against the mandrel bar as is desired in view of the temperature and quality of the metal being rolled.

. It will be understood that after the tube has been rolled, Whether with elongation only as in Fig. l, or elongation and expansion as in Fig. 3, the tube and mandrel bar may be removed from the pass line and the 'tube withdrawn from the mandrel bar.

Subsequently, that bar or another is again placed in the working position between the roll pairs ready for the piercing and rolling of the next billet.

lVhile all the rolls illustrated are disk-.

shaped, I wish to include by the expression rolls, when not otherwise qualified, barrel shapes, disk shapes, and other forms when arranged to cross roll and treat the metal as described.

I claim the following:

1. The continuous process of piercing and elongating billets comprising piercing the billet by subjecting it to cross rolling between cross rolling bodies and a mandrel bar, and as theibillet advances on the mandrel bar progressively and simultaneously elongating the tube and reducing the wall thicknessby subjecting it to cross rolling pressure on the mandrel bar at a plurality of portions of its length between a plurality of pairs of convex cross rolling bodies with progressive increase of the ratios of feeding to cross rolling speed components.

2. The continuous process of piercing and elongating billets comprising piercing the billet by subjecting it to cross rolling between cross rolling bodies and a mandrel bar, and as the billet advances on the man drel bar progressively and simultaneously elongating the tube and reducing the wall thickness by subjecting it to cross rolling pressure on the mandrel bar at a plurality of portions ofits length between a plurality of-pairs of convex cross rolling bodies with progressive increase of the ratios of feeding to cross rolling speed components, and progressively and simultaneously smoothing the exterior surface of thetube by cross rolling pressure between surfaces that are substantially parallel with the axis of the pass. I

3. The continuous process of piercing and elongating billets comprising piercing the billet by subjecting it to cross rolling pressure between rolling bodies and a mandrel bar, and as the billet advances on the bar progressively and simultaneously subjecting it to cross rolling pressure by successive pairs of convex cross rolling bodies with progressive increase of the ratios of feedm Y to cross rolling speed components.

4. The continuous process of piercing and elongating billets comprising piercing the billet by subjecting it to cross rolling pressure between rolling bodies and a mandrel bar, and as the billet advances on the bar progressively and simultaneously subjecting drel bar progressively and simultaneously elongating the tube and reducing the wall thickness and also expanding the tube by subjectin it to cross rolling pressure on the mandrel Tar ata plurality of portions of its length between a plurality of pairs of convex crossrolling bodies, and passing the tube expanded by one pair of rolls ontoa larger diameter of the mandrel bar, where it is cross rolled by-the succeeding pair with an increase in the ratio of feeding to'cross rolling speed components. I

6. The continuous process of piercing and elongating billets comprising piercing thebillet by subjecting it to cross rolling between cross rolling bodies and a mandrel bar, and as. the billet advances on the mandrel bar progressively v and simultaneously elongating the tube and reducing the wall thickness and also expanding the tube iii) by subjecting it to cross rolling pressure on the mandrel bar at a plurality of portions of its length between a plurality of pairs of convex cross rolling bodies, passing the tube expanded by one pair of rolls onto a larger diameter of the mandrel bar, where it is cross rolled by the succeeding pair with an increase in the ratio of feeding to cross rolling speed components,'and progressively and simultaneously smoothing the exterior surface of the tube by cross rolling pressure between surfaces that are substantially parallel with the axis of the pass.

7. Apparatus for piercing and elongating billets, combining a mandrel bar, means for holding said bar-against 'endwise thrust, and a plurality of separate pairs of'cross rolling rolls arranged in series, one of the said pairs being set to act adjacent to the point of the mandiel bar and having rolling faces adapted for piercing a billet, and one or more. of theasucceeding roll pairs being adapted for reducing the Wall thickness and set to act upon the tubular portion of the piercecl'billet upon the said mandrel bar.

8. Apparatus for piercing and elongating billets, combining a mandrel bar, means for holding .said bar against endwise thrust, anda plurality of separate pairs of cross rolling rolls arranged in series, one of the said pairs being set to act adjacent to the point of the mandrel bar and having rolling faces adapted for piercing a billet, and one 0r.more of the succeeding roll pairs being adapted-for reducing the Wall thickness and set..to. act upon the tubular portion of the pierced billet upon the said mandrel bar,

{and .snioothing .rolls having rolling faces substantially fiat and parallel along the pass which are set to act upon the billet'as it progresses. along the said mandrel.

9. Apparatus for piercing and elongating billets, combining a mandrel bar, means storev holding said bar against endWise thrust,and

a plurality of separate pairs of crossrolling rolls' arranged in series, one of the said pairs being set to act ad acent to the point of the mandrel bar andzhaying rolling faces adapted for piercing a b1lli ,-3.llCl one. or.

the said mandrel bar having one or more portions of larger diameter between the later roll pairs for acting on expanded portions of the tube.

In testimony whereof I have signed this specification in the presence of two subscribing witnesses, this 29th day of June, 1912.

RALPH CHARLES STIEFEL.

Witnesses:

G. E. MoYnR, M. E. NOLAN

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