US2778253A - Apparatus for rolling tubes - Google Patents

Description

Jan. 22, 1957 B. BROWNSTEIN APPARATUS FOR ROLLING TUBES 5 Sheets-Sheet 1 Original Filed March 12, 1954 mm H INVENTOR. Ben 0min Browns/em BY i 7 J11) fl g M TORNE Y5 mm mm 3 om mm mm mm Jan. 22, 1957 B. BROWNSTEIN 2,778,253

APPARATUS FOR ROLLING TUBES Original Filed March 12, 1954 5 Sheets-Sheet 2 i 5 E i K Mu 000 ME ON uh On mm m mm Jan. 22, 1957 B. BROWNSTEIN 29 3 APPARATUS FOR ROLLING TUBES Original Filed March 12, 1954 5 Sheets-Sheet 3 1111 E) 20] o T! E l 0' a 7 4O) A V" I E q -44 g g v 'IIII 1 5 IN VEN TOR. Ben 0min Bro wnsle/n H /S ORNE Y5 1957 B. BROWNSTEIN APPARATUS FOR ROLLING TUBES 5 Sheets-Sheet 4 Original Filed March 12, 1954 IN VEN TOR.

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Jan. 22, 1957 B. BROWNSTEIN 2,

APPARATUS FOR ROLLING TUBES Original Filed March 12, 1954' 5 Sheets-Sheet 5 INVENTOR. Ben 0mm Browns/em "M, )4 mm APPARATUS FOR ROLLING TUBES Benjamin Brownstein, Ellwood City, Pa.

Original application March 12, 1954, Serial No. 415,897. Divided and this application January 10, 1955, Serial No. 480,750

2 Claims. (Cl. 80--11) This invention relates to apparatus for rolling tubes and includes a mandrel and accessory equipment which is preferably but not necessarily used with the mandrel.

During the rolling of tubes, a mandrel is not only subjected to elevated-temperatures, for example in excess of 2000 F., but also to enormous radial compressive forces and longitudinal tensional forces which are exerted by the mill rolls on the sides of the mandrel. This results in distortion and considerable wear on the mandrel which in time must therefore be discarded.

The rolls of adjacent mill stands are commonly placed around the circumference of the mandrel at stations 90 degrees apart. As a result, substantially the same peripheral areas of the mandrel constantly receive the brunt of the forces exerted by the mill rolls. Additionally, when the mandrel contacts a hot tubular ingot in a rolling mill, the intense heat, particularly in multi-stand mills where there is less opportunity for the mandrel to cool, and weight of the mandrel cause it to sag. Accordingly, a thin wall is formed at the bottom of a tube being drawn over the mandrel and a correspondingly thicker wall at the top, thereby resulting in a tube which must be rejected.

The present invention provides a mandrel having a materially prolonged useful life and also provides accessory equipment to operate it and to increase further the life of the mandrel and counteract a tendency of the mandrel to sag. More particularly, the present invention provides a mandrel which, having become so worn that it would be otherwise discarded, may be very simply reconditioned to produce a new mandrel equally as effective as it was originally. The accessory apparatus of my invention with which the mandrel is preferably used further prolongs the life of the mandrel, even between such reconditioning operations, by distributing the wear about the entire periphery of the mandrel. I also provide novel auxiliary equipment to support the mandrel tates Patent between mill stands and prevent sagging thereof as the rolling operation proceeds.

In one form, my mandrel has stepped portions at one end and a plurality of removable collars adapted to fit around the mandrel and bear against a head portion. By so machining the mandrel as to preserve the stepped portions and removing one or more collars to compensate for any resulting decreased length of the mandrel, the effective length of the mandrel may also be preserved. A table advances the mandrel to and from a rolling mill and automatically rotates the mandrel in response to its movement to distribute the wear on all sides of the mandrel. Within the rolling mill, a support engages the mandrel between mill stands, and in response to the rolling of a tube around the mandrel and through the rolls of the mill, the support alternately withdraws from and re-engages the mandrel.

The accompanying drawings illustrate a presently preferred embodiment wherein:

Figure 1 is a plan view of my mandrel;

Figure 2 is a side view of the mandrel of Figure l and 2,7 78,253 Patented Jan. 22, 1957 also illustrates the mandrel after it has been reconditioned in accordance with the present invention;

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Figures 3 and 4 are side and end views, respectively,

of a collar used on the mandrel;

Figures 5 and 5a are plan views of a table and supporting conveyor which advance the mandrel to and froma rolling mill;

Figure 6 is a side view of the table and supporting conveyor;

Figure 7 is an enlarged fragmentary view of the table and supporting conveyor in which the overhead racks are removed for purposes of illustration;

Figures 8, 9, and 10 are sections of Figure 7 on the lines VIII-VIII, IX-IX, XX, respectively;

Figure 11 is a section of Figure 9 on the line XIXI;

Figure 12 is a side view of the inlet table to the rolling mill;

Figures 13 and 14 are plan and side views, respectively, of two mill stands embodying my mandrel support; and

Figure 15 illustrates a diagrammatic circuit for operating the mandrel support.

The mandrel Referring principally to Figures 1 through 4, my mandrel 20 is solid or tubular and has stepped portions 21 of progressively decreasing diameters in a direction toward the forward end of the mandrel. The mandrel also has a head portion spaced from the stepped portions which in the embodiment shown takes the form of a split coupler 22 uniting the enlarged ends 23 and 24, respectively, of the mandrel and a mandrel extension 25. A key 26 is inserted between the enlarged ends 23 and 24, and the sides of the coupler 22 are held together by bolts 27. The extension 25 has a bearing area 28 and an end 29 of square cross-section.

A plurality of collars 30 are juxtaposed on the mandrel between the stepped portions and the head portion and bear against the latter. The collars may be split longitudinally to facilitate fitting on the mandrel. The upper part 31 has a lug 32 which interfits with a similar but oppositely directed lug 33 of the lower part 34. Each collar has a conical extension 35 and each collar, except collar 30a, has a conical recess 36 to receive such an extension. This improves the interfitting of the collars on the mandrel and in the case of collar 30a spreads the bearing load against the coupler 22 throughout the thickness of that collar. Set screws 27a fix the collars to the mandrel.

The table and supporting conveyor Figures 5 through 11 illustrate a table for carrying the mandrel and a supporting conveyor which advances the table and mandrel to a rolling mill for a rolling operation and then retracts those parts to allow another heated tubular ingot to be positioned before the mill. The supporting conveyor includes suitable framework 37 comprising vertical posts 38 and beams 39 carried by the posts. The beams support upper tracks 40 and lower tracks 41 on which wheels 42 of a pair of roller chains 43 and 44 ride. The chains are of the endless conveyor type, each passing around spaced-apart sprockets, such as sprockets 45 and 46. The shaft 47 of the rearward sprockets is conventionally driven by a motor 48 through a gear reducer 49 and intermeshing gears 50 and 51.

The chains carry a table generally shown at 52 in Figure 7. The table includes a platform 53 linked at opposite ends to the chains 43 and 44 by lugs 54 and which, there fore, also travels the tracks 40 and 41. The platform 53 has a cross-arm 53a carrying a bearing 55 which receives the bearing area 28 of the mandrel extension 25.- The platform 53 also includes a frame 56 having'a bearing 57 and adapted to house means for at least partially rotating the mandrel 20 about a longitudinal axis in response to its movement to or from the rolling mill. A shaft 58 journaled for rotation in the bearing 57 has a socket 59 at one end to receive the square end 29 of the mandrel extension and a concentric gear 6.0 -at the other-end. An additional shaft 61 ismounted transverselyof. the. platform 53 and is carried at its terminals by bearings 62 (Figure 9) and inwardly of the terminals by bearings 63, allof which are supported by the platform 53. Between bearings 63,. the shaft :61 has a worm; gear fidxengageable with the concentric gear 60 on shaft 58. Between the bearings 62 and 63 at each end, the shaftsl has a fixed ratchet 65 straddled by ratchet arms 66 and 67. The ratchet arms are adapted for relative. movementwith the shaft 61 and are pinned together at their corresponding extremities. Pin 68 carries afreely pivoting pawl 69 which is urged against the ratchet 65- by a spring 749. A holder 71 pivoted to ratchet arm 67 houses one end of the spring. The outer ratchet arms 66 have integral annular flanges 72 to which i gears 73 are keyed. Fixed overhead racks 74 engage gears 73.

.Forwardly of the platform 53, the table 52- includes cross-arms '75 to support the mandrel 20 and mandrel extension 25. Each cross-arm includes a bracket 76- in which a pair of idler rollers 77 are journaled. The mandrel 20 rests on and between the rollers 77 and in this manner is rotatably mounted on the table. Because the diameter of the mandrel decreases toward the leading end, the cross-arms at that end are correspondingly higher to maintain the mandrel in a desired plane. To this end, adjustable screws 78 position the brackets 76 at a proper elevation with respect to the cross-arms 75.

Figures a and 12'illustrate an inlet table generally shown at 79 on which a heated tubular ingot rests before the mandrel is advanced by the table and supporting conveyor to introduce the tubular ingot and mandrel into the rolling mill. A base 81 fixed to a sub-base 82 has side frames 83 and 84 in which V-shaped rollers 85 are journaled. The shafts 86 of the rollers are interconnected at one side of the table 79 by gears 87 and shaft 86a is conventionally driven. A support 88 extends above the rollers 85 and has an opening 89 of sufiicient diameter to admit the mandrel 20 but insufiicient in diameter to pass the collars 30. A recess 90 corresponds in size to a collar and receives the foremost collar on the mandrel. The support 88 may also have idler rollers 91 journaled therein which coincide with the lower arc of the opening 89 to reduce wear on the mandrel passing therethrough.

While only one mandrel, table, and supportingconveyor are shown and described, it is understood that, as indicated by the broken-away portions of Figure 10, several mandrels, tables, and supporting conveyors can be used. The mandrels are placed parallel to each other and operated as a unit. The unit is moved transversely across the entrance of the inlet table to bring the desired mandrel in line with the opening 89. In this way one mandrel may be used while another is cooling.

T he mandrel support In order to support the mandrel along its length during the forward and return strokes by the table and support conveyor, and also to counteract the tendency of a mandrel to sag when in the mill due to the intense heat and weight of the mandrel, I provide a mandrel support between stands. Figures 13 and i4 illustrate two mill stands, generally shown at 92 and 93,. which embody such a support.

A shaft 94 is journaled at the rear of stand 92 in bearings 95. A bracket 96 fixed to the shaft 94 carries an idler roller 97 on a stub shaft. A bracket 98 also fixed to the shaft 94 pivotally engages a piston rod 99 of a fluid-actuated cylinder 100.

Similar to the shaft 94, shafts 101 and 102 are journaled for rotation at the entrances of the mill stands 92 and 93, respectively. Shaft 101 carries a fixed bracket 103' having a stub shaft 104 on which a follower 105 is mounted. A lever 106 is also fixed to the shaft 101 and has an arcuate slot 107 in which a link 1118 may be fixed at any desired point by a nut 109 which engages a threaded pin (not shown) extending from the link 108 through the slot 107. The slot 107 permits adjustment of the described parts to adapt them to mandrels and tubular ingots of varying diameters. Movement of the link 108 by the lever 106 operates a reversing electrical switch 110. With one exception, shaft 102 has parts similar to those of shaft 101. These parts are designated by the same reference numbers with the addition of the letter a. The exception is switch 111 which is non-reversing instead of reversing. Movement of the link 108a away from the switch 111 opens it.

As illustrated in Figure 15, switch 110, having electrical feed lines 112, is connected by lines 113 and 114 to a solenoid 115 which reciprocates the valve stem of a four-way reversible valve 116. Line 113 serially contains the non-reversing switch 111. Valve 116 has an inlet pipe 117 and an outlet pipe 118 for fluid such as air. Pipes 119 and 120 conduct the fluid from the valve 116 to opposite sides of the piston in the cylinder 100.

Operation In an overall operation, a heated tubular ingot, thickwalled tube, or like article is taken from soaking pits, for example, and directed down skids 121 onto the inlet table 79. The table 52 and supporting conveyor advance the mandrel 20 through the opening 89 of the support 88, through the heated tubular ingot, and between the rolls of the mill stands. At this time also, the mandrel contacts the roller 97 of the mandrel support which is normally in a raisedposition. The mandrel continues its forward movement until the foremost collar 30 reaches the mating recess 90. in the support 83 where the mandrel is brought to a stop and remains stationary for the duration of the rolling operation.

While the. mandrel support may, if desired, be used in a mill apart from the described table. and supporting conveyor, the cooperation between the mandrel support and the table and supporting conveyor in the present instance is here emphasized. In the usual rolling mill, the mandrel travels along with the tube as it is rolled. In contrast, as mentioned, the present mandrel is stationary during the rolling operation. Accordingly, to insure proper positioning of the mandrel within the mill as well as support it, the mandrel support cooperates with the table and supporting conveyor by maintaining the mandrel in a true pass line within the mill during the forward and return strokes of the conveyor. In this respect, the mandrel support is an accessory of the supporting conveyor and not the mill.

The forward movement of the mandrel also serves to introduce the tubular ingot into the mill stand 92 where the rollers 122 begin rolling the tubular ingot on the mandrel in a conventional manner. As the leading end of the embryonic tube approaches the stand 92 it lifts the follower 10S and bracket 103 thereby causing the lever 106 on shaft 101 to pull the link 168 away from the reversible switch 110. Since switch 111 is closed at this time, tripping switch 110, as described, operates valve 116 through the solenoid 115. This causes the fluid to flow to cylinder through pipe 119 and out pipe 120, thereby lowering the piston rod 99. This, in turn, pivots the shaft 94 and withdraws the roller 97 from the mandrel 20 and out of the path of the oncoming tube. When the leading end of the tube approaches stand 93 and rollers 122a, it similarly lifts follower a and the bracket 1il3a. Since this merely opens the non-reversing switch 111, there is no change. As the trailing end of the tube being rolled passes follower 105, bracket 103 drops to its original position, thus again reversing the switch 110. Because the circuit is open at switch 111, there still is no change. When the trailing end of the tube reaches stand 93, however, the follower 105a drops to its original position, thereby closing switch 111 and completing the circuit. Switch 118 being in a reversed position now operates the solenoid to reverse the position of the valve stem in valve 116, and the fluid flow to the cylinder ltlil is through pipe 32d and out pipe 119. The piston rod 99 therefore rises, rotates the shaft 94 in an opposite direction, and raises the roller 97 to its original position in which it supports the mandrel in a true pass line.

After the tube has been completely rolled and removed from the mandrel, the table 5'2 and supporting conveyor retract the mandrel from the rolling mill. In so doing, the gears 73 on the transverse shaft 61 engage the fixed racks i4 and turn the ratchet arms 66 and 67 about the shaft. As shown in Figure 11, the teeth of the ratchet 65 so slant a to engage the pawl 69 during this rotation. It will be apparent, however, that the teeth can slant in an opposite direction so that the ratchet and pawl engage on a forward movement of the table 52 instead of a rearward movement. In either case, the shaft 61 becomes locked with the ratchet arms and therefore also rotates, thereby causing shaft 58 to rotate as well by means of the intermeshing worm 64 and gear 60. Accordingly, on the next forward movement of the mandrel between the rolls of the mill stands, different peripheral areas of the mandrel directly receive the brunt of the forces exerted by the rolls. The amount the mandrel is rotated is not critical to my invention, but ordinarily the mandrel is rotated about 45 degrees. Thereafter, another heated tubular ingot is transferred to the inlet table and the operation as described is repeated.

Supporting the mandrel between the mill stands and rotating the mandrel as described materially prolong the useful life of the mandrel. However, due to the tremendous pressures and intense heat to which it is subjected, the mandrel eventually becomes too worn for continued service. In the present invention, when this occurs, instead of discarding the mandrel, it is reconditioned to provide a mandrel equally as effective as it was originally. Referring to Figures 1 and 2, to recondition my mandrel one or more of the collars 30 are removed, and the tip of the mandrel is out 01f a distance equal in length to the axial length of the removed collars. In the drawings this length is represented by x. The worn areas on the sides of a mandrel are then machined off so that the diameter of at least part of each stepped portion 21 is reduced to that of an immediately adjoining stepped portion, that is, all the stepped portions are machined back along the mandrel a distance equal to x. The number of collars removed depends on the axial length of the stepped portion which is machined away. This, in turn, is determined in part by the general condition of the mandrel, location of the worn spots, and the like. In any case, the same number of stepped portions always remains. Further, since the length of the mandrel from the foremost collar to the tip of the mandrel is always constant, it follows that the relative positions of the stepped portions 21 within a rolling mill are also always the same. In this manner, the mandrel can be reconditioned again and again until the machining reaches the head portion of the mandrel.

This is a divisional application of my copending application filed March 12, l954, entitled Apparatus for Rolling Tubes, and assigned Serial No. 415,897.

While the foregoing disclosure describes a presently preferred embodiment, it is understood that the invention may be practiced in other forms within the scope of the following claims.

I claim:

1. Apparatus for rolling tubes in a mill including a table, an endless chain secured to opposite sides of the table, corresponding tracks to guide the endless chains, a mandrel mounted on the table for rotation having a con centric gear at one end, a shaft mounted on the table transversely thereof having a worm gear engageable with the concentric gear, means to reciprocate the chains in their tracks whereby the mandrel is thrust forwardly and retracted, and means responsive to the movement of the table to rotate the shaft and thereby the mandrel whereby in each successive thrust different areas of the mandrel are directly subjected to the forces of the mill rolls.

2. Apparatus for rolling tubes in a mill including spaced-apart, substantially parallel endless conveyor chains, spaced-apart sprockets to receive each chain, means to reciprocate the chains in the direction of their lengths, a table secured at opposite sides to the chains, a shaft disposed longitudinally of the table and mounted thereon for rotation, cross-arms forward of the shaft extending from one chain to the other, a mandrel, means on the cross-arms to rotatably support the mandrel in a desired plane, a coupler to secure an end of the mandrel to an end of the shaft, a concentric gear on the shaft, 21 second shaft mounted on the table transversely thereof and having a worm gear engageable with the concentric gear, an annular flange concentric with the transverse shaft and adapted for relative movement therewith, ratchet means coupling the flange and transverse shaft together during rotation of the flange in a predetermined direction, a gear mounted on the flange, and a rack fixed with respect to the table and engageable with said gear on the flange whereby reciprocal movement of the table and chains rotates the flange and when in said predetermined direction also rotates said Worm gear and concentric gear on the longitudinally disposed shaft so that in each successive thrust of the mandrel different peripheral areas are directly subjected to the forces of the mill rolls.

References Cited in the file of this patent UNITED STATES PATENTS 954,880 Peters Apr. 12, 1910 1,263,251 Inshaw Apr. 16, 1918 1,386,115 Jenkins Aug. 2, 1921 1,890,803 Coe Dec. 13, 1932 1,928,811 Burns Oct. 3, 1933 1,950,929 Olsen Mar. 13, 1934 1,952,841 Coe Mar. 27, 1934 2,303,314 Anater Dec. 1, 1942 2,386,864 Inslee Oct. 16, 1945 2,686,444 Reichl Aug. 17, 1954 FOREIGN PATENTS 548,651 Germany Apr. 16, 1932

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