US2827810A - Mandrel structure for rolling tubes - Google Patents

Description

March 25, 1958 B. BROWNSTEIN 2,827,810

MANDREL STRUCTURE FOR ROLLING TUBES Filed March 12, 1954 5 Sheets-Sheet 1 IN V EN TOR. Eenj am in Bro wn stein w; M g-M HIS R/VE rs March 25, 1958 B. BROWNSTEIN 2,327,310

I MANDREL STRUCTURE FOR ROLLING TUBES I Filed March 12, 1954 5 Sheets-Sheet 2 ELF;

.IN V EN TOR. Benjamin Bro wnsfein M, km HIS A OR/VEYS I March 25, 19.58 B. BROWNSTEIN 2,827,816

MANDREL STRUCTURE FOR ROLLING TUBES Filed March 12, 1954 5 Sheets-Sheet 4 L il u- Y I I I INVENT F g ,2 Benjamin Browns! "M km,

1415 AT R/VE rs March 25, 1958 B. BROW STEIN 2,827,810

MANDREL STRUCTURE FOR ROLLING TUBES Filed March 12, 1954 5 Sheets-Sheet 5 INVEN TOR. Benjamin Brawnsfe n Uniteci States Fatent MANDREL STRUCTURE FOR ROLLING TUBES Benjamin Brownstein, Ellwood City, Pa.

Application March 12, 1954, Serial No. 415,897

1. Claim. (Cl. 73.-103).

This invention relates to apparatus for rolling tubes and includes improved mandrel structure andaccessoryequipment which is preferably but not necessarily used with the mandrel.

During the rolling of tubes, at 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 intime 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 pe-. ripheral 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, theintense heat, particularly in multi-stand mills where there is less opportunity for. the mandrel to cool, and weight of the mandrel cause it tosag. Accordingly, a.v 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 provide accessory equipment to operate it and to increase further the life ofthe 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 whichthe 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 mandrelbetween mill stands and prevent sagging thereof as the rolling operation proceeds.

lnone form, my mandrel has stepped portions atone 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 eflective length of the mandrel may also be preserved. A table advances the mandrel to and'from arolling mill and automatically rotates the mandrel in response to its movement to distribute the wear on all sides of the man-. drel. 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 they rolls of the mill, the support alternately withdraws from and reengages the mandrel.

The accompanying drawings illustrate a presently preferred embodiment wherein:

Figure 1 isa plan view of my mandrel;

Figure 2vis' a sideview of the mandrel DfFig re land also. illustrates the mandrelafter it has been reconditioned in accordance with] thepresent invention;

Figures 3 and 4 are side and end views, respectively, of a collar used on the mandrel;

Figures. 5 and 5d are pla'nviewsof a tableeand sup porting conveyor Whichadvance the mandrel to and from a rolling mill;

Figure 6 is a, side view .of the, table and supporting conyeyor;

Figure 7 isVanenlargedfragmentary view of the table and supporting conveyor in whichthe. overhead racks are removed for purposes of illustration;

Figures 8, 9, andj10 .are sectionsof Figure7 on the lines VIII-V111,, iX.-IX, X.X, respectively;

Figure 11 is a section ofFigureQonthe lineXIX[;

Figure 12 is a sidevieW 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 ISiIlustrates a diagrammatic circuit for operating the mandrel. support.

The mandrel- Referring principally to. Figures 1 through 4, my mandrel.20 is solid or tubularand has stepped portions 21 of vprogressively decreasing diameters .in a, direction to: wardv the forward end of the mandrel... The mandrel also has. a headportion spacedfrom the stepped portions which in the embodiment shown takes the form of a split coupler 22 uniting the enlarged ends 23 and24, 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 abearing area 28 and an end 29 of square cross-section.

A plurality of collars 39 are juxtaposed on the mandrel between the stepped portions and the head portion and bear against the latter. The collars may-be split longitua dinally to facilitate fitting on the mandrel. The upper part 31 has a lug 32 which interfits with a similar butoppositely directed lug 33 of the lower part 34. Eachcollar has a conical extension35 and each collar, except collar 39a, 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. Setscrews 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 operations and then retracts those 'partsto 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 49 and lower tracks 41 on which wheels .42 of a pairof 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 5 2 inFigure 7. The table includes a platform 53 linked at opposite ends to the chains 43 and 44 by lugs 54 and which, therefore, 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 arframe 56 .havinga bear- .the opening 89 to to the shaft 94'pivotally engages a piston rod. 99 of fluid-actuated cylinder 10%.

ing 57 and adapted to house means for at least partially rotating the mandrel 20 about a longitudinal axis in re sponse to its movement to or from the rolling mill. A shaft 58 journaled for rotation'in the bearing 57 has a socket 59 at oneend to receive the square end 29 of the mandrel extension and a concentric gear 60 at the other end. An additional shaft 61 ismounted transversely of the platform 53 and is carried at its terminals by bearings62 (Figure 9) and inwardly of the terminals by bearings 63, all of which are supported by the platform 53.

'Between bearings 63, the shaft 61 has a worm gear 64 engageable with the concentric gear 60 on shaft 58. Between the bearings 62 and .63 at each end, the shaft 61 has a fixed ratchet 65 straddled by ratchet arms 66 and 67. The ratchet arms are adapted for relative movement with the shaft 61' and are pinned together at their corresponding extremities. Pin 68'carries a'freelypivoting pawl 69 which is urged against the ratchet 65.by a spring 70. 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 gears 73 are keyed.

.Fixed overhead racks 74 engage gears 73.

'Forwardly of theplatform 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; diameter of the mandrel decreases toward the leading end, the cross-arms at that end are correspondinglyhigher to maintain the mandrel in a desired plane. 7 To this end,

adiustable screws 78 position the brackets 76 at aproper elevation with respect to the cross-arms 75. 7

Figures 5a 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 33 and 84 inwhich V-shaped rollers 85 are journaled. The shafts 86 of the rollers are interconnected at one side of the table 79by' gears 37 and shaft 86a is conventionally driven. A support 88 extends above the rollers 85 and has an opening 39 of sufiicient diameter to admit the mandrel 2% but insufiicient 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 reduce wear on the mandrel passing therethrough." I I 7 e i While only one mandrel, table and supporting con- 7 veyor are shown and described, it is understood that, as 7 indicated by the broken-away'portions of Figure 10, severarmandr els, tables, and supporting conveyors can be used. The mandrels are placed paralleltoeach other and operated as a unit. The unit is moved transversely across the entrance of the inlet'table to bring the desired mandrel in linewith the opening "89. In this way one mandrel may be used while another is cooling. 1

The mandrel support i L' ing the forward and. return'strokesfby the table andsupport conveyor, and also to counteract the tendency of'a mandrel to sag when in .the rnilldue. to the intense heat and weight of the mandrel, .1 provide a mandrel support between stands. Figures 138.I1d.1.4: illustrate two rnill stands, generally shown at 92 and 93, whichembody such asupportl- A shaft 94 is journal-ed at the rear of stand 92 in bearings 95. A bracket-96 fixed: to thes haft'94 carries an idler roller 97 on a stub sha ftr A bracket 98 also. fixed simnanto the shaft 94, shafts rot and 1012 are am;

Because the naled for rotation at the entrances of the mill stands 92 and 93, respectively. Shaft 101 carries a fixed bracket at any desired pointby 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. by the lever 106- operates a reversing electrical switch 110. With oneexception, 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 nonreversing instead of reversing. Movement of the link 198a away from the switch 111 opens it.

'As illustratedin Figure 15, switch 110, having electrical feed lines 112, is connected by lines'1l3and'11'4 to a solenoid 115 which reciprocates the valve stem of a fourway 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 oppositesides of the piston in the cylinder 190.

Operation 7 In an overall operation, a heated tubular ingot, thick walled tube, orlike article is taken from soaking pits, for

V continues its forward movement until the foremost collar I example, and directed down skids 121 onto the inlet 30 reaches the mating recess 9tl in.the support 88 where the mandrel is brought to. a stop and remains stationary for the duration of the rolling operation. a

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 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, thennandrel support cooperates was 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 s upport is an accessory of the supporting conveyor and not the mill. 7 The forward movement of the mandrel also serves to introduce the tubular ingotinto the mill stand 92 where the rollers 122 begin rolling the tubular ingot on the mandrel in a conventional manner. As the leading end 7 lever 106011" shaft 101 to pull the link'10S away from.

of the embryonic'tube approaches the stand 92 it lifts the follower fand'bracket 103 thereby causing the the reversible switch 11 .59. Since switch 111 is closed at this time, tripping'switch 110, as described, operates valve. 7 116 throught'ne solenoid 115. This causes the fluid to.

fiow to cylinderfltltlthrough-pipe 119 andout pipe 120,

thereby lowering the pistonrod'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 105a and the V bracket 103a. 7 Since. this merely opens the non-reversing switch 111, there is no change. the tube being rolled passes follower 105, bracket 103 7 76 drops to its original position,'thus again reversing; the

Movement of the link 108 At this time also,

In the usual rolling mill, the mandrel travels along with the'tube as it is rolled.

As the trailing end of 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 110 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 100 is through pipe 120 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 52 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 74 and turn the ratchet arms 66 and 67 about the shaft. As shown in Figure 11, the teeth of the ratchet 65 so slant as 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 cut off 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 am'al 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.

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 claim.

I claim:

For use with an inlet table having a support member provided with a mandrel receiving opening, a solid mandrel of one-piece construction having cylindrical elongated stepped wear surface portions, each succeeding portion being of decreasing diameter, a head portion on the mandrel spaced from the stepped portions, a plurality of removable stop collars juxtaposed on the mandrel at an unused portion between the head portion and the stepped portions and individually removable to expose the unused portion to the extent that the mandrel is shortened each time it is reconditioned, said stop collars being of sufiiciently large diameter to prevent their passage through said receiving opening thereby effectively stopping against said support member and the stop end portion of said stop collars having a tapering bearing surface adapted to engage said support member.

References Cited in the file of this patent UNITED STATES PATENTS 424,213 Kellogg Mar. 25, 1890 1,052,848 Schilling Feb. 11, 1913 1,386,115 Jenkins Aug. 2, 1921 1,770,649 Kirkrnan July 15, 1930 1,890,803 Coe Dec. 13, 1932 1,950,929 Olson Mar. 13, 1934 1,952,841 Coe Mar. 27, 1934 2,212,688 Jones Aug. 27, 1940 2,263,744 Smith Nov. 25, 1941 2,356,734 Bannister Aug. 29, 1944 2,569,104 laenchen Sept. 25, 1951 2,686,444 Reichl Aug. 17, 1954 FOREIGN PATENTS 604,013 Germany Oct. 12, 1934

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