US2356734A - Tube mill - Google Patents

Description

B. BANNISTER TUBE MILL Aug. 29, 1944.-

Filed Aug. 14, 1941 3 Sheets-Sheet 1v Qmm@ .H -m E N v Q le n [n I|\ Q B K www@ wmb HNS m. yb

B. BANNlsTER y TUBE MILL Aug. 29,1944.

Filed Aug. 14, 1941 s lsheets-sheet 2 Aug. 29, 1944. a. BANNISTER TUBE MILL Filed Aug. '14, 1941 3 `Sheets-Sheet 3 *Ill QQME

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Patented Aug. 29, 1944 TUBEMILL- Bryant Bannister, Mount Lebanon, Pa., assigner to National Tube Company, a corporation of New Jersey 'Application August 14, 1941, serial No. 406,894

9 claims. (ci. so-11) The present invention relates to a tube-mill layout for the manufacture of seamless pipe.

' The manufacture of seamless pipe comprises,

` in general, the steps of piercing a solid cylin drical billet, reducing the wall and elongating the pierced billet, and nally planishing and sizing the pipe so produced, to the desired dimensions: One specific method which is employed comprises piercing the billet, rolling the billet in a continuous-type mill wherein a series of grooved rolls compress the metal against a mandrel which floats through the mill with the billet, stripping the rolled tube from the mandrel, and reheating thetube, after which it is reduced to nal size.

The mandrel referred to above forms an internal support for the tube, and it is not mounted nor attached to anything. Consequently, said to oat through the mill.

One object of the present invention is to simplify very greatly the production of seamless tubes by eliminating many of the operations now employed, thereby effecting a substantial reduction in operating costs, as well as a reduction in the cost of installation required to produce pipe.

Another object of the invention is to improve itis a continuous-type sizing or sinking mill immediately following the continuousr mill. In order to employ only this limited equipment, thereby eliminating a bar-stripper, reheating furnace, and extensive tables, conveyors and the like, there is employed, in accordance with the present invention, a mandrel in conjunction with the continuous rolling mill, which mandrel is inserted through the pierced billet, and on which the billet is rolled,.but which is restrained or held from floating freely through the mill. The mandrel, however, is permitted to move forward, during the rolling of the tube, a distance approximating twice the distance between adjacent roll centers in the continuous mill. Since the alternate roll stands are disposed with theirrolling planes at right angles to each other, this limited mandrel movement precludes the rolling of the pipe on any one position of the mandrel more than once. l

This mandrel control arrangement permits the continuous mill to strip the rolled tube from thev the quality of the pipe produced, by the elimiy nation of reheating with its consequent tendency to pit the surfaces, and the avoidance -of variable temperatures in the pipe during processing, which variable temperatures cause irregularities in dif ameter and wall thickness.

In accordance with the practice which has become accepted as being standard, after the pipe has been rolled on the floating mandrel through the continuous mill, it is' necessary to employ a. stripping 'die or other means to effect the stripping of the rolled pipe from the mandrel. Following this operation, the stripped pipe has cooled to such an extent that it is necessary to reheat the pipe before it is sent to the sizing mill or to the sinking-sizing mill, where it is brought to substantially final dimensions. This procedure increases the installation and operating costs quite substantially.

Furthermore, there is required considerably more handling than is necessary to produce the desired result-s, as it is not practicable to arrange the units of the equipment is alignment with each other, which may be stated to be a further object and advantage of ,the present improved system. 3

Generally speaking, inthe practiceoi the present invention, there are employed a billet-heating furnace, a continuous-typerolling mill and mandrel, thus projecting the forward end of the tube into the tandem sinkingmill which then continues to strip the tube from the mandrel after the back end has passed the last stand of the continuous rolling mill, thus rendering unnecessary an extra roll stand to round up the tube which has been rolled by the mill into an oval shape, which has been caused by the action of the rolls of the mill as the wall-thickness of the pipe has been reduced. The extra rounding stand is essential when the mandrel oats through the mill with the pipe.

The present invention permits the placement of a sizing or sinking mill immediately in line with, and only a few feet removed from, the last stand of the continuous mill. As this continuous mill is operated at highl roll speed, the tube enters the sizing mill at a temperature sufciently high,'without recourse to reheating, to permit' Y sizing or sinking to a much smaller diameter.

' the mandrel being withdrawn far enough to permit the' pierced billet to be dropped into the charging trough just ahead ofthe mill. The

mandrel then is advanced toward the'mill, passing through the pierced billet and into the roll 'passes of,the mill.` As the mandrel advances, a

collar on the rear end of the mandrel engages the billet, pushing it forward to enter the mill.

The movements are controlled so that, as the billet enters the rst roll stand, the forward end of the bar or mandrel is at the last roll stand of the mill. At this point, the rolls grip the pierced billet and draw it into the mill. At this stage, the forward movement of the mandrel is restricted so that it moves forward slowly, traveling only a few feet while the billet is being rolled.

Where the mill is producing small diameter pipe, the mandrels are small and several are employed in rotation. While one mandrel bar is being rolled upon, others are circulated through a cooling bath and returned one at a time to the mill. Large mills are able to employ one mandrel, which is water-cooled, such a mandrel remaining in service until wear necessitates its removal.

With the foregoing considerations in mind, at-

. 33, and delivers the fluid through a pipe 35 into a tention may be given to the accompanying drawings which illustrate diagrammatically the foregoing considerations.

In the accompanying drawings:

Figure l .is a general arrangement of a tube mill;

Figure 2 illustrates the apparatus in starting position, with a pierced billet ready to receive the mandrel, and with the mandrel control mechanism in starting position for beginning the operation;

Figure 3 illustrates the condition when the billet is ljust entering the continuous mill: the mandrel being almost at the end travel;

of its rapid forward' four-way. valve 31. A pipe 39 connects the valve 31 to the cylinder IIVand enters the cylinder in front of the piston head 2l. A pipe il connects the valve to the sump 33. l

The cylinder II opens at its rear end into a pipe 93, which branches into two lines 35 and ill. Branch 35 contains a quick-acting valve (I9, and branch 31 includes a constant volume valve 5I, the orifice of which is small compared with that of the valv'e 39, so that ow of uid is largely through valve 99, unless this valve is closed. The branches 35 and 91 connect' through pipe 53, which leads tothe sump when valve 31 is in the position shown in Figs. 2 and 3.

The operation becomes clear from through 6.

Asshown in Figure 2, at the start of the operations, the valve 31 is open so that uid is being delivered from the sump 33 through the pipe 39 and into the cylinder II in front of the Piston head 2i. The valve 49 is open so as to relieve pressure behind the piston head 2l. Therefore, the pressure of the uid entering the cylinder II through pipe 39 moves the piston head back Figures 2 through the-cylinder II, forcing the uid behind Figure 4 illustrates the conditions when the A rolled tube is just leaving the continuous mill and is passing through the sizing or sinking mill, with the mandrel being in its fully extended position, and being shown as having moved forward only a short distanceduring the passage of the tube-billet through the continuous mill;

it out through pipe B3 and branches 35 and 41, valves 49 and 3|, and back to the sump through pipe 53. l

This action thrusts the mandrel bar I3 through the pierced billet I5 and when the collar 29 in the mandrel I3 engages the billet and brings it to the first stand of rolls in the continuous mill I1, the valve 49 is closed and the -uld passes through the small orice of the constant volume valve See Fig. 3.-

This retards the outward movement of the mandrel I3 which is secured at one end by the socket Figure 5 shows the sized tube just leaving the sizing mill, the mandrel b`ar having returned to its lretracted position and released ;v

'Figure 6 ispsimilar to. Figure 1, completing the operating cycle, with a new billet ready to be run through the mills and a new mandrel bar in position. The view shows, also, means for releasing and replacing the mandrel bars;

Figure 7 is a diagrammatic detail of the man-.

drel bar handling mechanism; and

Figures 8,.9, and 10 are successive diagrammatic views of the rolling of the tube, the -views showing the relative 'movement between the mandrel'.

bar and tube during the rolling operation.

Referring more' particularly to the drawings, the reference' numeral II represents a means for actuating a mandrel bar I3 for pushing a pierced billet I5 through a continuous reduction mill I1, the resulting tube passing through a sinking-mill I9, the respective mills being disposed in tandem alignment.

It will be understood that the actuating means II may be any one loi' several types, as has been pointed out above herein, and the control which will be described hereinafter likewise'is intended to illustrate simply a control which will be operative to serve the intended purpose.

In the illustrated embodiment of the invention, the 'actuating-device is a cylinder containing a hydraulic piston which is made up of a, piston head 2| and a piston rod 23, the rod 23 terminating -a socket-25 for receiving the ball end 21 of t e mandrel bar I3. The mandrel bar I3 has a push collar 29 adjacenttothe ball 21.

The control system is illustrated as compris- 25. The result is that the forward movement of the mandrel I3 is much less in itsspeed than is the movement of the billet I5 through the mill.

This results in the mill I1 stripping the now elongated billet from the mandrel, the forward movement of which mandrel is controlled so that it reaches its maximum extension just as the end of the tube is leaving the continuous mill. It will be observed that the tube enters the sinking mill I9 before it' entirely leaves the continuous mill I1, and it will be noted that the mandrel I3 having reached its farthest point of extension b eppnd the mill I1, the tube will be supported substantially throughout its entire length as it moves through the mill I9.'

When the tube has cleared the last stand of4 the continuous mill Il, the valve 31 is turned so as to connect the pipe 39 with the sump, and

pipe 53 with the pump 3I. Simultaneously valve that a suitable lifting means SII, which may be a.

the min l1.

-4'9 is opened so that the pump 3| now forces fluid into the cylinder I I behind the piston head 2| so as to retract quickly the mandrel I3. See Fig. 4.

The return of this mandrel, as well as its outward movement, is in line with the center line of As-the bar I3 returns to startingr positiomit is quickly disconnected from the socket 25 bysuitabole means, which means may be such as those shown in Figure 7.' It will be seen cylinder 66 is actuated, which lifts a mandrel I3 up between guides 61 onto anincline, which drops the bar into place in socket 25. Referring to Figures 8, 9 and -10, it will be noted that the continuous mill .I 1 is made up of a plurality of stands of rolls, each stand being positioned at 90 with respect to the preceding and succeeding' stands, so that the billet will be rolled on subplane occupies the long diameter of the oval and does not contact the mandrel I3.

Figures 8, 9, and 10 show clearly the relative movement of the billet and mandrel bar'I during passage through the mill. As the billet I5 enters the first stand of rolls 55, the mandrelbar I3 has passed a considerable distance through the mill. The billet I 5 as it enters the mill is pressed against the mandrelbar I3, as shown at contact 59. When this rst contact has been made, the further forward movement of the mandre'l bar I3 is controlled so that no portion of this bar shall move a distance greater than twice the dis'tance between the center lines of sequential stands of vertical rolls. That is to say, in Figure 9, when the billet `I5 has been rolled to form the tube I5", the original contact line 59 will have moved only to the designated location at`59a,

and when the'tube I5 is leaving the last stand of rolls, the original contact line 59 has reached only the location indicated by 59h. That is to say, the bar has moved a distance not quite equal to that between the center linesof adjacent horizontal roll stands, it being understood that the roll stands are equally spaced. Consequently, this limited mandrel movement precludesV the rolling of the billet I5 into the tube I5' on any one `portion of the mandrel'more/than once.

` From the foregoing, it will be seen that after the tube has been rolled completely in the continuous mill the sinking mill continues to .strip' the rolled tube from a portion of the mandrelcontinuous projecting beyond the last stand of mill rolls. Y

It will be seen, accordingly, that the present invention permits the arrangement of the continuous rolling mill and the sinking mill to be placed in tandem alignment, and that the movement of the mandrel bar likewise is in alignment with the mills. It will be seen further that the arrangement of the present invention eliminates reheating the work, and eliminates also the customary stripping stand which has been necessary heretofore lThe immediate and direct passage of the tube from the continuous mill to the sinking mill prevents substantial loss of heat from the work during such passage; and because the work enters the sinking mill before it entirely leaves the continuous mill, and since the mandrel bar is not withdrawn until substantially the rear end of the work is ready to enter the sinking mill, the Work is supported during substantially its entire course of travel through the mills. However, it will be evident that it is not essential that the Vrolled tube be supported by the mandrel after it has cleared the continuous mill, since a supporting trough normally is provided betwee continuous mill and sinking mill for this purpose. Also, the control mechanism for the mandrel acts to start the mandrel Ibar re- Also, the control mechanism for the mandrel 4 limits the forward motion of the-mandrel so that it cannot at any time enter the first stand of rolls in the sinking mill.

It will be apparent that as the pierced billet is rolled into a, tube in the continuous mill, the mandrel bar functions as an internal anvil upon which the metal of the billet is compressed by the rolls of the continuous mill.

'Ihe billets I5 are supp0rtedin a suitable trough in alignment with the mandrel bar I3 and continuous mill I' I, it having been received in the said trough, which is designated at I6 on the drawings, from the piercing mill, preferably without reheating;` although, if desired, the pierced billets may be reheated in a suitable furnace before being handled in accordance with the present invention.

I claim:

1. Apparatus for making seamless tubes, which comprises, in combination, acontinuous mill, a sinking mill, and means for delivering a, pierced billet into the continuous mill, the mills and delivering means being in alignment, the said delivery meansA including a semi-floating mandrel bar adapted to enter the billet and support the same during its conversion into a tube in the continuous mill, the mandrel continuing its forward movement duringworking'of the billet in the continuous mill, and means for retarding forward movement of the mandrel relative to the tube in the continuous mill, thereby causing the tube to be stripped from the mandrel in the mill` the said continuous mill and sinking mill being positioned sufficiently closely together to enable the tube to pass substantially" and with continuo-us movement into the snking'mill before it has entirely cleared the continuous mill.-

and the said mandrel forming a support for the tube after it has cleared the continuous mill until subtantially allof the tube has passed through the sinking mill, there being no interruptionto continuity of movement 'of the `tube between the continuous min and the sinking min.

2. Apparatus for producing seamless tubes. which comprises, in combination, aligned continuous and sinking mills and means in alignment with the said mills for delivering a pierced billet thereto, the said means including al semifloating mandrelbar adapted to push the said billet, and to preventthe'rolling of the tube on billet,l into the continuous mill and to support the resulting tube as it is formed in the milly through its entire passage through the mill, and means for controlling `the forward movement of.

the mandrel tofeiectI a differential in speed ,between the forward motion of the bar and the when the billet` has entered the sizing mill, the tube entering and passing through the sinking mill without vinterruption to movement of the tube between the continuous mill and the sinking mill. f

3. Mechanism for producing seamless tubes, which comprises a continuous mill anda sinking mill in closely adjacent and 'aligned relationship, means for introducing the pierced billet into the continuous mill and for supporting the billet through the mill as it is rolled into a tube, and controlling mechanism for the said means for limiting forward movement of the said means during actual rolling of the billet to a distance not more than twice the distance between the center lines of adjacent stands in the mill, the sinking mill being adapted to receive the resulting tube substantially immediately as it emerges from the continuous mill. Y

4.*Apparatus for making seamless tubes, which comprises, in combination, a continuous mill, a sinking mill in tandem alignment`with the continuous mill, means for delivering a pierced billet into the continuous mill, the delivering means being in tandem alignment with the mills, the said delivery means including an internal anvil for the pierced billet dellning an internal support for lthe billet against which the metal of the billet is compressed during rolling, the continuous mill and the sinking mill being positioned sufllciently closely together to enable the tube to pass substantially into the sinking mill before it has cleared entirely the continuous mill and means for retracting the said internal anvil from theAthus-rolled tube as the sinking mill acts upon the tube to draw the tube through the said sinking mill, the tube passing with a continuous and uninterrupted movement through the said mills.

5. Apparatus for making seamless tubes, which comprises, in combination, a continuous mill, a sinking mill, and mechanism for feeding a pierced billet therethrough, all of the foregoing units being in tandem alignment, the feeding means comprising a mandrel, anactuating bar for the mandrel, a connection between the mandrel and the bar, the said connection holding the mandrel in a semi-iloating condition, operating mechanism for the bar for causing the man drel to move into a pierced billet for feeding into the continuous milland for continuing forward movement of the mandrel as the billet moves through the continu-ous mill and is formed into a tube therein and control mechanism for retarding the forward movement of the mandrel as the billet passes through the continuous mill thereby eil'ecting a speed diierential between the mandrel and lthe'billet to allow the resulting tube to be stripped as formed from the mandrel, while the mandrel continues its forward movement to a point beyond the continuousmill and intermediate the continuous mill and the sinking mill, the sinking mill being sufliciently close to the continuous mill to allow direct and continuous passage .of the resulting tube from the continuous mill to the sinking mill, the said mandrel dening a support for vthe tube until substantially the -entire length of the tube has entered the sinking mill.

. 6. Apparatus for producing seamless tubes, which comprises, in combination, aligned continuous and sinking mills and means in alignment with the said mills for delivering a pierced billet thereto, the said means including a semiiioating mandrel bar adapted to push the said the resulting. tube as it is formed in the mill through its entire`passage through the mili, actuating -instrumentalities for the mandrel, mechanism for operating the actuating instrumentalities for selectively advancing and retracting the mandrel, meansremovably interconnecting the mandrel and actuating instrumentalities and mechanism -for removing a mandrel from the actuating instrumentalities at Icompletion of each cycle of passage of the billet and mandrel through the continuous mills and for replacing the said mandrel with a new mandrel for the next succeeding passage through the mills.

7. Apparatus for producing seamless tubes. which comprises, in combination, aligned lcontinuous and sinking mills and means in alignment with the said mills for delivering a pierced billet thereto, the said means including a semifloating mandrel bar adapted to push the said billet into the continuous mill and to support the resulting tube as it is formed in the mill continuous through its entire passage through the` mill, actuating instrumentalities for the man- 8. Apparatus for producing seamless tubes,

which comprises, in combination, aligned continuous and sinking mills and means in alignment with the said mills for delivering a pierced billet thereto, the said means including a semifloating mandrel bar adapted to push the said billet into the continuous mill and to support the resulting tube as it is formed in the mills through its entire [passage through the continuous mill, actuating instrumentalities for the mandrel, mechanism for operating the mandrel-actuating instrumentalities for selectively advancing and retracting the mandrel, means removably interconnecting the mandrel and mandrel-actuating instrumentalities, and mandrel-handling mechanismfor removing the mandrel from the mandrel-actuating instrumentalities at completion of each 'cycle of passage of the billet and mandrel through the mills and for replacing the said mandrel with a `new mandrel for the next succeeding passage through the mills, the mandrel-handling mechanism including a stand for receiving a plurality of mandrels, rocker-arm instrumentalities for receiving a mandrel. actuating means for the rocker-arm instrumen- 'talities, whereby operation of the actuating means causes alifting of the said rocker-arm billet into-the continuous mill and to support 75 instrumentalities to enable the rocker-arm instrumentalities to lpick up a mandrel out of its interconnection with\the mandrel-actuating instrumentalities, while` reverse operation of the actuating means deposits the removed mandrel nto the said. stand, d instrumentalities or placing successive fresh mandrels from the stand ontothe rocker-arm instrumentalities forA replacement of, the said successive mandrels into interconnection with the mandrel- `actuating instrumentalities.

9. Apparatus for producing seamless tubes, which comprises, in combination, aligned continuous and sizing mills and `means in alignment with the said mills for delivering a pierced billet thereto, the said means including a semifloating mandrel bar adapted to push the said billet into the said continuousmill and to supmentalities, and mandrel-handling mechanism for removingthe mandrel from the actuating instrumentalities at completion of each cycle of passage of the billet and mandrel through the mills and for replacing the said mandrel with a- Y new mandrel for the next succeeding passage A `through the mills, the mandrel-handling mechanism including a stand .for receiving a plurality of mandrels, rocker-arm instrumentalities for receiving a mandrel, actuating 'means for the rocker-arm instrumental-ities, whereby operation of the actuating means to cause a lifting o f the said rocker-arm instrumentalitiesto 4en able the said rocker-arm instrumentalities to pick up a' f mandrel out of the interconnection with the actuating instrumentalities, while reverse operation of the actuating means deposits the removed mandrel onto the said stand, lifting'mea'ns for lifting successive fresh mandrels from thel stand,

and a gravity feed for shifting each lifted man-v drel from the lifting means tothe rocker-arm instrumentalities for placement into the interconnection with the mandrel-actuating instrumentalities. v

BRYANT BANNISTER.'

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