US1997997A - Mandrel for tube rolling mills - Google Patents

Description

April 16, 1935. A. P. DlEscHER 1,997,997

I MANDREL FOR TUBE ROLLING MILLS Filed March 5, 1933 s sheets-sheet 1* zz zo z3 FIG 2.

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MANDREL FOR TUBE ROLLING MILLS Filed March 5, 1933 5 Sheets-Sheet 2 l@k z FI G. 4 za I @www Mmmffm A TTOF/VEY April 16, 1935.

A. P. DIESCHER MANDREL FOR TUBE ROLLING MILLS Filed March 5, 1933 3 Sheets-Sheet 5 Sw NM wh R. bv Q .5 @www Patented pr. 16, 1935 REL FR TUBE RELING MILLS August P. Biescher, Pittsburgh, Pa., assigner to Diescher Tube Mills,

lino., Pittsburgh, Pa., a

it) Claims.

My invention relates to apparatus for treating tubular blanks, and particularly to mandrels for use in treating tubes of relatively large diameters by means of cross-rolling.

In reducing the wall thickness and increasing the length of tubes in a cross-rolling mill, it is advisable to employ a mandrel the outside diameter of which is smaller than the inside diameter of the finished tube. When the tubes are of relatively large internal diameter it will be appreciated that the weight of a solid mandrel of the necessary diameter may be such as to damage lthe relatively thin walls of a completed tube which encloses it when they are delivered from. the crossrolls.

A hollow mandrel of sufficient wall thickness to resist the forces exerted by the cross-rolls upon the tubular blank would be lighter than a solid mandrel, but its weight would still be excessive in connection with the handling of the completed large tube with the mandrel in the interior thereof.

In accordance with the present invention, I provide a relatively light tube, orv cylindrical shell, the wall thickness of which is ysufilcient to withstand all of the stresses to which an elongator mandrel may normally be subjected in handling but is not sucient to withstand the forces of cross-rolling vthat tend to crush the mandrel during the elongation of a tubular blank; and I provide in the interior of the hollow shell a reinforcing plug which may rotate with the hollow shell but is retained in its longitudinal position between the cross-rolls for receiving the forces of the latter as the tubular blank and the hollow shell pass therethrough. y

The hollow cylindrical shell may therefore ad- Y vance through the rolls and rotate with the tubular blank during its elongation,'while the reinforcing plug in the interior thereof remains in its longitudinal position but may rotate with the shell. By means of this arrangement, I am enabled to provide a mandrel member to move with the tube of suiiiciently light construction to be easily handled and to avoid damaging, by reason of its Weight, the highly heated thin walls of tubes of large diameter as they emerge from the crossrolls.

The details of my invention will be described in connection with the accompanying drawings, in which,

Figure l is a plan view of a portion of an elongator in operation upon a tubular blank having a mandrel constructed in accordance with my in- (ei. rsu-its) vention, the blank and mandrel being in horizontal section and parts being broken away.

Fig. 2 is an enlarged longitudinal sectional view oi a portion of the mandrel of Fig. l.

Figs. 3 and 4 are views similar respectively to Figs. 1 and 2 of a modification.

Fig. 5 is a longitudinal sectional view of a portio of a mandrel of further modied construction.

Fig. 6 is a ytransverse sectional view taken on line VI-VI oi Fig. 5.

Fig. 7 is a similar view on line "VE-VII of Fig. 5. Fig. 8` is a front end elevation of the mandrel of Fig. 5.

mandrel 4 therein.

The mandrel l comprises a relatively light cylindrical shell 5 that is provided Witha conical head 6 which is screw-threaded into an end piece l and fastened therein by Ymeans of a suitable rivet 8. The end piece l is secured to the shell 5 by means of the rivet B and rivets 9.

A reinforcing plug il! is located in the interior of the shell 5 for the purpose of resisting the crushing forces exerted by the cross-rolls upon the tubular blank 3 and shell 5 as they pass through the elongator. The plug I vcomprises a hollow cylindrical member l and secured to the forward l having tapered ends end of a tubular rod i2 which retains the assembly of the plug Il) in its illustrated longitudinal position,

The member i i has a close or running t with the interior of the shell and may rotate with the latter. The rod l2 may be secured at its left-hand end, not shown, by any suitable vmeans such, for example, as a thrust bearing which will restrain the rod l2 and the plug IllV from longitudinal movement to the right as viewed in Fig.- 1, but which will permit the rotation of these parts with the shell 5.

The hollow member Il is mounted, upon a reduced portion of the rod l2 and is suitably keyed thereto by a key- I3. The member Il is secured upon the rod l2 by means of a bushing nut I4 screw-threaded on the forward end of the rod I2 and prevented from rotation by a suitable rivet l5. The interior of the tubul ar rod l2 is provided with a tube I6 that is spaced from the interior wall of the rod i2 and is secured to the forward end of the latter by means of interior screwthreaded bushings l1 and I8. The tube I6 serves as an inlet for water for cooling the interiorl of the conical head 6 and of the hollow shell 5 of the mandrel 4 andthe walls of the tapered member Il. The space around the tube I6 within the tubular rod I2 affords a. passage having an outlet through a radial tube I9 for a suitable lubricant for the interior surface of the shell 5 whereby the latter may move over the reinforcing plug I0 without undue friction therebetween which might otherwise be caused by the pressure exerted upon the plug I0 by the shell 5 because of the forces exerted by the cross-rolls I and 2.

In the operation of an elongator employing my improved mandrel, a tubular blank is provided with a hollow shell 5 and a plug I0 is inserted within the shell 5 against the mandrel head 6 at any suitable point in the travel of the blank and mandrel to the cross-rolls. It is preferable that the thrust block or other device for retaining the rod I2 and the connected plug I0 in their longitudinal positions be so arranged that it may advance with the plug iii and the shell 5 and tubular blank 3 until the plug I0 is in its working position between the cross-rolls as illustrated in Fig. 1.

When the tubular blank 3 enters the cross-rolls it is drawn longitudinally therethrough and rapidly rotated and the mandrel shell 5 which is closely engaged by the tubular blank 3 moves in the same directionv as the latter, but not necessarily at the same rate. The plug IIJ, however, re-

mains in position between the cross-rolls in the zone in which forces are exerted by the crossrolls in reducing the Wall thickness of the blank 3 upon the mandrel 4. It will be appreciated that no wall-reducing forces are exerted upon the portion of the completed tube that has passed through the cross-rolls and is beyondthe plug I0.

During the cross-rolling operation water is supplied through the tube I6 and it flows intothe forward portion of the shell 5 beyond the plug. It is desirable that the water be supplied under such pressure and at such rate that itsvolume beyond the plug will increase more rapidly than the space beyond Vthe plug I0 in order that it will be under pressure to insure a satisfactory rapid return flow.

The cooling water returns along the shell 5 and through a series of inclined openings 20 in the wall of the hollow member II to cool the latter. This cooling effect is increased by the rotation of the plug I0 since any water entering the openings 20 in the forward end of the plug will flow around at least a portion. of the interior of the hollow member II before it flows out through the p openings 29 at the rear of the member II. The returning cooling water continues to the trailing end of the mandrel shell, whereupon it may be either cooled and recirculated or disposed of in any suitable manner.

In case such operation appears desirable, the direction of flow of cooling water may be reversed, the ,water being supplied through the shell 5 surrounding the tube I2. This arrangement insures an adequate supply of cooling water to the plug I0 at all times since it flows through .the openings 20 before passing to the forward end of the mandrel. Water will not return until it reaches a level in the forward end of the mandrel that permits it to flow into the forward end of the tube I6.

The cross-rolling operation continues until the entire blank 3 has passed through the cross-rolls to the delivery side of the elongator.

If the elongating apparatus is of the type in which the mandrel is returned to its starting point by passing around the elongator in the manner described, for example, in my copending application Serial No. 602,145, led March 31, 1932, it will be necessary that the plug I8 be Withdrawn after the elongation of each tube and for such distance from the cross-rolls on the entry side thereof as will permit a fresh mandrel shell to be placed into position to enter the crossrolls. The plug may then be advanced into the forward end of the fresh mandrel shell at any suitable time before the tubular blank enters the cross-rolls. All of these parts are then advanced into the cross-rolls.

In the event that the elongating apparatus is of the type wherein the mandrel is stripped from the completed tube by drawing it back through the cross-rolls after each elongation, the plug I0 must be withdrawn along with the mandrel shell for such distance as is suiiicient to permit the next tubular blank or billet to be disposed in the elongator inlet between the mandrel head or point and the elongator. In withdrawing the mandrel shell in this manner the plug Il) will necessarily be carried with it after the mandrel head has engaged the forward end of the rod I2 to the forward end of which is connected to the stem 22 by means of a washer 25 and an internal bushing 26.

A tapered nozzle 21 has a screw-threaded connection to the interior of the hollow stem 22 and is in alignment with the pipe 24. Between the bushing 26 and the rearward end of the nozzle 21 is a series of radial openings 28 that extend through the stem 22 and communicate with the hollow interior of the tapered member II. lIfhe nozzle is also provided with radial openings 29 adjacent its screw-threaded connection to the stem 22.

In the operation of this form of my invention,

water is supplied through the pipe 24 and it is forced forwardly through the nozzle 21 toward the forward end of the mandrel. In addition a certain amount of water flows radially through the radial openings 28 for the purpose of cooling the interior of the member II. Water also flows radially through the openings 28, this portion of the water flowing at the forward end of the stem 22 into the shell adjacent the forward end of the hollow member I I.

It is possible that during the operation of the cross-rolls the mandrel shell 5 may advance with the tubular blank 3 at such rate as compared to the rate of water supply that the water does not ll the rapidly increasing space in front of the member II. In such case water from the space in front of the memberll will not flow back through the front and rear openings' 20 of the member I I. It is important therefore in such case that means such as the radial openings 28 be provided in order to insure that a certain portion of the cooling water flows into the interior of the member I l. The nozzle 21 provides suflicient4 back pressure to the iiow of water through the pipe 24 that water will fiow radially through the openings 28 and also through the openings 29 for the purposes described above.

In case the forward end of the mandrel is not lled by the cooling water, the nozzle 21 will operate to so increase the velocity of the water that it will be thrown a considerably greater distance toward vthe forward end of the mandrel than 'would be the case if the water owed through a pipe of uniform bore.

Reference may now be had to Figs. 5, 6, 7 and 8 in which is illustrated a further modification. As in the form of my invention shown in Figs. 3 and 4, the member II is provided with a central stem 30 to which is connected a tubular rod 23. A pipe 24 is connected to the stern 30 in the manner de scribed in connection with the apparatus of Figs. 3 and 4.

The forward end of the stern 30 is provided with a bushing 3| through which projects a pipe 32 that is rigidly connected to a bushing 33 in the head of the mandrel. The pipe 32, which is provided with a series of radial openings 34 adjacent the head of the mandrel, has a loose telescoping iit with the pipe 24, these parts overlapping to such extent as to permit the movement of the mandrel shell during the operation of cross-rolling a tube without the tube 32 being completely withdrawn from the pipe 24.

'I'he mandrel head comprises a tubular bushing 36 that is secured to the forward end of the shell 5 by means of rivets 31 and an approximately conical nose portion 38 is screw-threaded to the bushing 33, the latter having a similar connection to the tubular bushing 36. As shown in Fig. 8 the nose portion 38 is provided with two recesses 39 whereby the nose 38 may be removed from or replaced upon the bushing 33. A screw 40 locks the nose 38 in its illustrated position.

In the operation of the latter form of my invention, water is supplied through the pipe 24 in the direction of the arrow in Fig. 5, water flowing into the pipe 32 and being discharged therefrom through the openings 34 at the forward end of the mandrel. Water also traverses the annular space between the pipe 24 and the pipe 32 and enters the annular space within the stem 30. The latter is provided with radial openings 4I through which water is forced into the interior of the hollow tapered member Il..

Water also iiows through the relatively small annular opening in the bushing 3l surrounding the pipe 32 and is discharged into the shell 5 adjacent the forward end of the member I I. 'I'he reiurn fiow of the cooling water is through the inclined openings 20 as in the other forms of my invention. If the rate of increase in the volume of the space within the mandrel shell in front of the member I I is faster than the rate at which water is supplied thereto. there may be liitle or no return flow through the openings 20 from such space. In such case, however, the arrangement whereby the water is transmitted to three portions of the mandrel insures that all of the essential parts of the latter will be cooled regardless of the relation of the rate of increase in space to that of the supply of Water. The openings 34 insure that the forward end of the mandrel will be cooled, and the openings 4I insure that water will be supplied to the interior of the member Il. The water flowing through the annular opening in the bushing 3| insures that some water will be directed to a portion of the shell adjacent the member II.

Mandrels constructed in variousforms in accordance with my invention permit the crossrolling of a tube of relatively large diameter upon a mandrel of such weight that it is easily handled and that the highly heated thin walls of the tube will not be damaged when the tube and the mandrel shell therein emerge from the cross-rolls. At the same time the strength of the mandrel shell reinforced by the plug contained therein is suiiicient to resist the crushing forces of the cross-rolls and to thereby insure that the elongation of the tubular blank will occur with the same efficiency and satisfactoryresults that would be secured if solid mandrels were employed.

'Ihe foregoing and other advantages will be apparent to those skilled in the art of construc-v out the latters annular extent as the shell progresses forwardly over the plug.

2. A mandrel adapted for use in a tube rolling mill, comprising a rod anchored at its outer end for rotation on its axis and against longitudinal movement, a plug having a cylindrical outer face attached to said rod and adapted to be held thereby in the working pass of a mill, and a long cylindrical blank-supporting shell slidably mounted for longitudinal movement upon said plug which is formed to reinforce said shell throughout the latters annular extent as the shell progresses forwardly over the plug.

3. A mandrel adapted for use in a tube rolling mill, comprising a rod held against longitudinal movement, a plug having a cylindrical outer face attached to said rod and adapted to be held thereby in the Working pass of a mill, and a long cylindrical blank-supporting shell slidably mounted for longitudinal movement upon said plug and provided at its forward end with a tapered head for entering the shell into a tubular blank, said plug being formed to reinforce said shell throughout the latters annular extent as the shell progresses forwardly over the plug.

4, A mandrel adapted foruse in a tube rolling mill, comprising a rod held against longitudinal movement, a plug having a cylindrical outer face attached to said rod and adapted to be held thereby in the working pass of a mill, and av long cylindrical blank-supporting shell slidably mounted for longitudinal movement upon said plug and having its forward end closed by a tapered head for entering the shell into a tubular blank said plug being formed to reinforce said shell throughout the latters annular extent as the shell moves forwardly over the plug.

5. A mandrel adapted for use in a tube rolling mill, comprising a, tubular rod anchored at its outer end against longitudinal movement, a plug having a cylindrical outer face attached to said rod and adapted to be held thereby in the working pass of a mill, a long cylindrical blank-supporting shell slidably mounted for longitudinal movement upon said plug and having its forward end closed, said plug being formed to reinforce said shell as the latter moves forwardly over the plug andpbeing provided with openings for the flow of cooling fluid t-hrough it and through said tubular rod.

6. A mandrel adapted for use in a tube rolling mill, comprising a tubular rod anchored at its outer end for rotation on its axis and against longitudinal movement, a plug having `a cylindrical outer face attached to said rod and adapted to be held thereby in the working pass of a mill, and a long cylindrical blank-supporting shell slidably mounted for longitudinal movement upon said plug and provided with an end-closing head which is tapered for entering the shell into a tubular blank, said plug being 'formedto re- I inforce said shell as the latter moves forwardly over the plug and being provided with openings for the ow of a cooling fluid through it and through said tubular rod and to the closed end of said shell.

'1. Av mandrel for use in a. tube rolling mill, comprising a long cylindrical shell adapted to advance longitudinally within a tubular blank during passage of the blank through the mill, a reinforcing plug Within said shell having a cylindrical outer face, and a rod extending within the shell and held at its outer end against longitudinal movement, said plug being attached to said rod and held thereby against longitudinal movement positioned in the working pass of the mill while the shell advances longitudinally.

8. A mandrel for use in a tube cross-rolling mill, comprising a long cylindrical shell adapted to rotate and advance longitudinally within a tubular blank during passage of the blank through the mill, a reinforcing plug within said shell having a cylindrical outer race, and a rodV extending within the shell and held at its outer end against longitudinal movement, said plug being attached to said rod and held thereby against longitudinal movement positioned in the working pass of the mill while the shell advances longitudinally, said plug being free to rotate with said shell.

9. A mandrel for use in a tube cross-rolling mill, comprising a long cylindrical shell adapted to rotate and advance longitudinally within a tubular blank during passage of the blank through the mill, a reinforcing plug within. said shell having a cylindrical outer face, and a rod extending within the shell and held at its outer end against longitudinal movement but free to rotate, said plug being attached to said rod and held thereby against longitudinal movement positioned in the working pass' of the mill while the shell advances longitudinally.

10. A mandrel for use in a tube rolling mill. comprising a long cylindrical shell adapted to advance longitudinally within a tubular blank during passage of the blank through the mill, a reinforcing plug within said shell having a cylindrical outer face, and a rod extending within the shell and held at its outer end against longitudinal movement, said plug being attached to said rod and held thereby against longitudinal movement positioned in the working pass of the mill while the shell advances longitudinally, and said rod and plug being provided with a passageway for supplying lubricant to the exterior of the plug.

AUGUST P. DIESCHER.

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