US2458110A - Apparatus for producing seamless tubes - Google Patents

Description

1949- E; c. SLEEMAN 2,458,110

APPARATUS FOR PRODUCING SEAMLESS TUBES Filed Nov. 7, 1944 s Sheets-Sheet '1 Jan. 4, 1949. c, SLEEMAN 2,458,110

APPARATUS FOR PRODUCING SEAMLESS TUBES 3 Sheets-Sheet 2 Filed Nov. 7, 1944 1; t n 28 3D 34 d 46 :2 f 3 42 If 40 l 5 4 r "f c v B s I" 1L :15-

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Patented Jan. 4, 1949 APPARATUS FOR PRODUCING SEAMLESS TUBES Earl 0. Bloom, Detroit, Micln, assignor to Detroit Seamless Steel Tubes Company, Detroit, Mich a corporation of Michigan Application November 7, 1944, Serial No. 582,309

'1 Claim. 1

This invention relates to an improved method 7 and apparatus for producing seamless tubes of ferrous and non-ferrous metals in a roll mill.

In the manufacture of seamless tubes there are several methods and types of apparatus now in use for performing the operations required vis: reducing the diameters, reducing the wall thickness, increasing the length and smoothing the outer and inner surfaces.

One method consists in passing a heated pierced seamless tube back and forth two or three times between a pair of rotating round rolls provided with grooves that form a substantially round opening and over a short round plug that is located in the opening. The plug is mounted on the end of a mandrel bar which is fixed relative to the longitudinal movement of the tube. Passing the tube through the rolls and over the plug produces a tube having a reduced diameter, a reduced wall thickness, and an increased length. The tube is then passed between another pair of rotating rolls that have their axes crossed and over a longitudinallyflxed, short, round plug 10- cated in the space between the rolls. This performs the operation of smoothing the outer and inner diameters. This method is limited and produces uncontrollable defects in the finished tube in that there is a tendency of the tube to overflll the groove, causing fins and laps to be formed on the outer surafce, formation of tears and scratches on the inner surface due to the sliding action between the tube and plug,' a reduction of the feed of the tube between the rolls due to the resistance of the plug, a limited number of passes that can be made due to the loss of heat in the tube, and excessive wear on the-plug.

Another method consists in placing the heated pierced seamless tube on a solid round mandrel M bar, then passing the tube and bar between a. pair of rotating rolls havingtheir axes crossed and simultaneously passing the tube and mandrel bar between a pair of rotating discs positioned between the rolls and above and below the tube. The peripheral speed of the discs is considerably greater than that of the rolls' and their direction of travel is opposed to that of the rolls and the rotation of the tube. This method and apparatus is also limited and produces uncontrollable defects in the finished seamless tube. Such defects cause the formation of scratches and other marks on the outer surface of the tube due to the opposed action of the discs on the rotating and forward feed'of the tube, excessive wear on the periphery of the discs due to the difierence in speed, and difficulty in keeping the discs in coriii rect position in relation to the rolls and to the pass line along which the tube and mandrel bar travel. This is particularly true when producing tubes of small diameters which require discs oi narrow width.

A further method consists in placing the heated pierced seamless tube on a solid round mandrel bar and passing the tube and bar between a group of three rotating rolls having their axes crossed. .The rolls are equally spaced around the tube and bar and form a working pass which produce a seamless tube. This method is unsatisfactory for producing finished seamless tubes or small diameters and thin walls. The relation of the outside diameter of the tube to the maximum roll diameter being approximately one to five it is apparent that to produce a small outside diameter tube it is impractical to mount the roll-s due to their restricted diameters. Due to the unsupported portions of the tube circumference in the pass the amount of wall thickness reduction is also limited. Large reductions cause the tube to bulge outwardly between the points of support and restrict it from rotating and feeding forwardly.

It is an object of the present invention to overcome the above listed difficulties and to provide new and useful apparatu which will produce finished seamless tubing in a manner which will not result in any of the defects as are produced with the methods and apparatus now in use.

Another object of the invention is to provide apparatus which will reduce the diameter of the tube, reduce the wall thickness. increase the length of the tube, and produce smooth outer and inner surfaces by a single pass of the tube through the apparatus.

- working passes in close proximity along the line of travel of the tube and the mandrel bar and to rotate and draw the mandrel bar and tube through the rolls by the rotation of the rolls in peripheral frictional engagement with the tube.

Other objects and advantages of the invention will be more apparent from the following description taken in connection with the accompanying drawings in which:

Fig.1;is a top plan view of that portion of a roll-mill; which embodies the present invention;

Fig. 2 is a side elevation of P18. 1; V Fig. 3 is an end view of the apparatus shown in Figs. 1 and 2;

Fig. 4 is an enlarged-fragmentary viewtaken on line -il of Fig. 3;

- amen-1o f I members 42, M, and 46 are arranged adjacent the working stations A, B, and C respectively and are positioned between the rolls as indicated in Fig. 5 is a view similar to Fig. 4 but taken on line 5--5 of Fig. 3;

Fig. 6 is a sectional view taken on line 8-8 of Fig. 4;

Fig. 7 is a sectional view taken on line 'l--I of Fig. 4;

Fig. 8 is a sectional view taken on line 88 of Fig. 4;

Fig. 9 is a sectional view taken on line 8-9 of Fig. 4;

Fig. 10 is a sectional. view taken on line iii- 40 of Fig. 5;

. Fig. 11 is a sectional view taken on line ll-ll of Fig. 5;

Fig. 12 is a sectional view taken on line [2-42 of Fi 5;

Fig. 13 is a sectional view taken on line |8l3 of Fig. 4; and

Fig. 14 is a sectional view taken on line il-H of Fig. 4.

Referring to. the drawings, only that portion diameters and required wall thickness of the tube.

Inoperation, 9. pierced seamless tube T, heated to the proper temperature, is placed in the end guide 38. A solid or hollow mandrel'bar 50, having a length greater than the finished seamless tube T, is pushed through the pierced tube T in the direction shown by the arrow D in Fig. 4 until its end is in line with the end of the guide 40 and retained in that position. The pierced seamless of the apparatus essential to'the invention has been illustrated. The drive mechanism, associated shafts, gears, etc., of roll mills, well known in the art, have been omitted and the operation of the device illustrated will be readily understood.

Four rotatable shafts 28, 22, 24, and 26 have been arranged around a central point which is the pass line X through which the tube to be formed passes longitudinally. The axes of the shafts 20, 22, 26, and 26 are positioned at angles of ninety degrees to each other around the longitudinal axis of the pass line X. The axes of the shafts 20 and 22 are positioned diametrically opposite and are each provided with axially spaced rolls 28 and 30. The axis of the shaft 28 extends at an angle to the axis of the pass line X and the axis of the shaft 22 extends at an angle to the axis of the pass line X but in a direction opposite to that angle between the shaft 22 and the pass line X.

The axes of the shafts 2B and 26 are positioned diametrically opposite and are each provided with a roll 32. The axes of the shafts 2d and 28 extend at an angle to the axis of the pass line X and each in oppositely extending directions. The axes of the shafts 2'0, 22, 24, and 26 may be radially adjustable and the diameters of the rolls 28, 30, and 32 are of a diameter to engage the outer periphery of the tube being worked upon when the shafts are disposed in proper position. The rolls 32 are positioned between the axially spaced rolls 28 and 30.

By this arrangement it will be noted that there have been provided three working stations, designated at A, B, and C, with the rolls contacting the outer periphery of the tube T at diametrically opposite points of the tube T. The rolls 28 form the working station A, the rolls 38 form the working station 0, and the rolls 32 form the working station B.

The rolls are each provided with a cylindrical surface 34 and a conical surface 38 both of which are coaxial withthe axis of its respective shaft.

Tubular end guides 38 and 48 are provided for receiving and guiding the tube T through the working stations. oppositely disposed guide tube T is then pushed in the direction of the arrow D between the conical surfaces 30 of the rolls 28 at the working station A.

The pierced tube T on reaching point M is gripped :by the diametrically opposed rolls 28. The rolls are rotating'at the same peripheral speed and the rotation and gripping action causes the tube to rotatein the direction indicated by the arrow E. Due to the angularly related axes of the shafts and rolls, sometimes referred to in the art as askew, and the rotation of the rolls,

the tube is fed toward the left in a direction indicated by the arrow D.

As the rotation and forward feed of the tube T continues, reductions in the outer and inner diameters occur and continues with no change in the wall thickness. until the tube T reaches the diametrically opposed points N. At this point a reduction of the outer diameter and wall thickness occurs. At the points N the inner diameter of the tube T, due to the pressure of the rolls, grips the round mandrel bar 50 and starts it rotating in the direction indicated by the arrow E at approximately the same rotating speed as that of the tube T at these points. The mandrel bar 50 also starts to feed forwardly in the direction of the arrow D due to the contact between the inner diameter of the tube T and the mandrel bar 58. I

As the metal in the tube T and the mandrel bar 50 continues to rotate and move forwardly from points N to points P, the outer diameter and wall thickness are progressively reduced, the inner diameter remaining the same. From points P to points It the inner and outer diameters and the wall thickness remain substantially the same. The inner and outer surfaces are smoothed and any irregularities in the wall thickness are corrected.

The tube T on leaving the first working station A, including points M, N, P, and R, assumes a substantially round form, the inner diameter being slightly greater than the diameter of the mandrel bar 50.

The action on the tube T at points M, N, P, and R causes the extruded portion of the tube T to have a considerably greater forward speed, due to its elongatiomthen that portion of the tube eritering the point M. Consequently that portion of the tube T leaving the working station A is moving longitudinally at a greater speed than that portion of the tube entering the working station A. It is therefore desirable to rotate the rolls 32 and 36 at a diiferent speed or at a different angular position with respect to the axis of the pass line X. This may be accomplished by either a difference in speed ofrotation, alteration of relative'axial angular relation or a 'combination of both to compensate for the increased forward travel of the elongated portion of the tube T.

-As that portion of the tube T enters the second working station B, it first comes in contact with points 8 on the conical surfaces 36 of rolls 32 and the inner periphery of the tube T is urged into contact with the mandrel bar 50 as indicated by the points U and at those points the conical surfaces further reduce the wall thickness and at diametrically opposite points engage the inner peripheryof the tube T with the outer periphery of the mandrel bar 50. The cylindrical surfaces 34 of the rolls 32 remain substantially the same throughout their rolling engagement with the outer periphery of the tube T and the wall thickness remain substantially the same. The inner and outer surfaces are again smoothed as by the surfaces 34 on rolls 28 and there is a further correction of any irregularities of the wall thickness.

The working station B includes the points illustrated on the drawings as points S, U, V", and W.

The continued longitudinal movement of the tube in its finished dimensions enters the third working station C. 'At this station the pressure is predetermined to exert only a rounding action to the elongated tube T. It will be noted that the pressure of the rolls 30 is insufficient to contact the inner periphery of the tube with the outer periphery of the mandrel bar 50. The cylindrical surfaces of the rolls 30 contact the outer periphery of the tube T, and the portion of the tube T leaving station C is cylindrical as illustrated in Fig. 13.

The method and apparatus herein described provides for the formation of a finished seamless tube in one pass through the device. The location and arrangement of parts permit the re quired cross rolling operations on a pierced seamless tube in three successive operations thereby producing a smooth finished seamless tube by reducing the, diameters, reducing the wall thick- 'ness, increasing the length and smoothing the of my invention or the method of formation, and

it is not my intention to limit its scope other than by the terms of the appended claim.

I claim:

A seamless tube rolling mill comprising, a pair of driven shafts arranged with their axes dia- I metrically opposed with respect to a pass line, a second pair of driven shafts arranged with their axes diametrically opposed with respect to said pass line and circumferentially spaced around said pass line from said first-named shafts, all said shaft axes being fixed against rotation about said pass line, the axes of said shafts being askew to each other and to the said pass line, two pairs of opposed rolls axially spaced and fixed on said first pair of shafts, and a pair of opposed rolls fixed to said second pair of shafts and disposed axially intermediate the said two pairs of rolls on said first shaft.

EARL C. SLEEMAN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name 1 Date 240,774 Seaman Apr. 26, 1881 401,144 Flagler Apr. 9, 1889 r 1,055,368 Stiefel Mar. 11, 1913 1,088,650 Brinkman Feb. 14, 1914 1,520,905 Lauren Dec. 30, 1924 1,800,891 Kocks Apr. 14, 1931 1,977,223. Abramsen Oct. 16, 1934 2,060,087 Klamp Nov. 10, 1936 FOREIGN PATENTS Number Country Date 259,623 Germany May 9, 19 3 3851940 Germany Nov. 30, 1923 424,211 7 Germany Jan. 19, 1926

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