US2074714A - Method of sizing round bars, wire, tubes, and the like - Google Patents

Description

March 23, 1937- P. B. ABRAMSEN 2,074,714

METHOD OF SIZING ROUND BARS, WIRE, TUBES, AND THE LIKE Filed Aug. 25, 1934 ,3 Sheets-Sheet 1 INVENTOR Pmfi. s l m & BM.

March 23, 1937. I P. B. ABRAMSEN 2,074,714

METHOD OF SIZING ROUND BARS, WIRE, TUBES, AND THE LIKE Filed Aug. 25, 19:54 5 Shets-Sheet 2 ,Flg. 2.

\J; v P 11230 2 I H J I a 21 x 129 ll 39 0 I 41 O J8 50 l INVENTOR 6 paw m March 23, 1937. ABRAMSEN 2,074,714

7 METHOD OF SIZING ROUND BARS, WIRE, TUBES, Am THE LIKE Filed Aug. 25, 1934 3 Sheets-Sheet 3 INVENTOR J PM 6.

JLLO WW Patented Mar. 23, 1937 UNITED STATES ME'rnon or SIZING ROUND nsna wmn, TUBES, AND THE LIKE Potter B. Abramsen, Dormont, Pa., assignor of one-half to Gustaf L. Fisk, Pittsburgh, Pa.

Application August 25, 1934, Serial No. 741,411

2 Claims.

This invention relates to the rolling a d sizing of round material within predetermined limitsof uniformity and accuracy. More particularly, this invention relates to a new mode of effecting a 5 reduction in the cross-section of such material, and novel apparatus for performing the desired rolling operation. This application is a continuation-impart of application Serial No. 661,920,

filed March 21, 1933.

As rolling of such material has heretofore been carried on, the reduction in cross-section of the rounds has been brought about in successive mill stands having the opposed grooved rolls mounted on parallel axes. The rounds, as delivered from the last mill stand, are generally not quite true because the accuracy of roundness depends upon both the true roundness of the groove in the opposed rolls of the mill and the proper spacing of these rolls. Accordingly, one or more passes through cross rolls is required to finish the shaping of the material.

I have discovered that it is not necessary to complete the reduction of the cross-section of the material by hot rolling in the mill stands. A cold rolling pass between opposed grooved rolls mounted on non-parallel axes will, under certain conditions, effect a reduction in round material. The opposed rolls must be driven in opposite directions. The rolls must be mounted on axes arranged at such angle relative to the direction of travel of the material sufliciently greater than 45 that simultaneously with the reducing action the material is rotated, with the result that the action of the rolls progresses along the material in spirals of length more than four times the diameter thereof, and preferably about eleven times the diameter.

This cold rolling procedure is to be contrasted with the usual practice using grooved rolls mount- 40 ed on parallel axes. 'In the latter type of mill stand, the pass imparts to the material its own contour; and if there is any inaccuracy in the roundness of the contour of the pass this inaccuracy shows up in the rolled product. In ac- 4 cordance with my improved procedure using grooved rolls mounted on non-parallel axes, the sizing action of the rolls starts when the material engages in the grooves adjacent the rim ofxthe latter; and as the sizing action progresses, the

50 contact between the material and the groove gradually shifts to the center of the latter and then toward the opposite rim. While the contact between the material and the groove is progressing in the manner just described, the material is 5 rotating to cause the contact between the groove and the material to progress along a spiral path on the material. The result is that a given portion of the surface of the material comes in contact with varying portions of the groove; and inaccuracies in the latter have a negligible effect 5 upon the roundness of the product.

If within rather narrow tolerances a pair of rolls is furnished for each cross-section desired, a product can be obtained, by exercising great care in setting the rolls both as to their spacing and 10 as to the angularrelation between the axes of the rolls and the direction of travel of the work, which will meet the usual requirements as to roundness and finish. As a practical matter, however, it is not only tedious to thus carefully 15 adjust the rolls, but it is also desirable that a given pair of rolls may, by adjusting the spacing and by change in the above-mentioned angularity of the rolls, be used for sizing a small range of cross-sections. In accordance with this more 20 flexible practice, the necessary variations in the spacing of the rolls result, even when compensation is made by way of change in the angularity of the rolls, in imperfections in the surface of the product which call for a smoothing and finishing 5 operation. This smoothing and finishing operation may be performed by a unit similar to the sizing unit, but with the rolls oriented to bring the axes at a small angle relative to the direction of the work as is customary for cross rolls used in 30 straightening and smoothing operations. In the unit used for the smoothing and finishing operation, the rolls will be provided with grooves of but slight concavity, and the rolls will be rotated in the same direction. 35

This method, calling for both a reduction in the cross-section of the material by a cold rolling pass between opposed grooved rolls and a smoothing and finishing operation, results in an im-' proved product, as the sizing-action takes place 40 progressively along a spiral whose length is more than four times its diameter and preferably about eleven times its diameter, whereas the smoothing and finishing operation is efiected in a short spiral, namely a spiral of length about equal to the diameter thereof. The relatively short spiral rolling following the long spiral rolling brings about suflicient compensation for any imperfections imparted to the surface of the product by the sizing operation as to result in a high degree of accuracy of roundness of the surface of the product.

The angularity of the axes of the sizing rolls with relation to the direction of travel of the material is, I have discovered, of critical importance. While it is well known that when cross rolls rotated in engagement with round material are disposed with their axes at a small angle with relation to the direction of travel of the mate rial, the eii'ect is to straighten the material, the effect of grooved rolls mounted on axes arranged at an angle greater than 4'5 relative to the direction of travel of the material has not heretofore been understood and made use of. I have discovered that this angle must be sufficiently, greater than 45 so that when simultaneously with the reducing action, the material is rotated, the action of the rolls progresses along the material in long spirals. With a small angle a smoothingand l6 finishing action can be obtained; but a reduction in the cross-section of the material cannot be effected with suflicient dependability to be used in regular commercial production of round material. The best and most reliable results are obtained when this angle between the axes of the rolls and the direction of travel of the material is increased to between about 70 and 75, and preferably between 72 and 75.

In contrast to the usual smoothing and straight- I ening operation, this sizing operation is performed by driving the opposed rolls in opposite directions. This is a cold rolling operation, and the hardness of the material is increased more than can be obtained by cold drawing through a die;

I and this increase in hardness minimizes tearing of the metal in automatic thread forming machines. The longer the spiral in which the rolls act upon the material, the greater the increase in hardness caused thereby. The working of the metal,

5 instead of causing harmful effects, is just enough to give good machining properties.

For a better understanding of my invention, reference may be had to the drawings illustrating certain embodiments which the same may assume, it being understood that these drawings are for the purpose of illustration and are not intended as limiting my invention. In these drawings- Figure 1 is a schematic plan view of apparatus for sizing and smoothing round bars, wire, and

the like;

Figure 2 is an enlarged plan view of the'unit for sizing the material, the mounting for the upper roll being shown in horizontal section;

Figure 3 is a diagrammatic plan view of the roll pass, the material being indicated in chain line;

Figures 4a and 411 show, partly in elevation and partly in vertical section, the upper and lower rolls of the unit shown in Figure 2, the two rolls being shown in separate figures so that each view may be taken parallel to the axis of the respective roll; and v Figure 5 is a diagrammatic plan view of an jarrangement of successive roll stands organized in: accordance with my invention.

The preferred arrangement of apparatus in ac-5= cordance with my invention is shown in Figurev l The successive lengths of material are transferred from the storage rack 8 to the conveyor rollsl; for feeding into the pass between the sizing rolls ll. This pass, which will be described in greater detail in connection with Figure 2, effects, in ac- V cordance with my preferred embodiment, the requisite reduction in cross-section; and the material. passes on through the guides l2 to the straightening and smoothing rolls It. It will be noted that inherently the sizing unit and the smoothing unit are the same except that the smoothing rolls are directly driven, are driven in the same direction, and are so oriented that the angle between the direction of travel of the work and the axes of the smoothing rolls is substantially complementary to this angle in the sizing unit. As the second unit is a smoothing and tinishing unit, the rolls, of course, have a much shallower groove; or, in other words, are more nearly cylindrical. The material deposited on the table ll after passing through the second unit,isof uniform diametersand cylindrical; within narrow limits.

It will be noted more particularly from Figure 3 that the opposed sizing rolls I0 have grooves of less sharply curved concavity than the grooves in the rolls of the usual mill stand. In other words, the arc of curvature of the groove of each roll is substantially longer than the radius of the work itself. In progressing through the pass the material engages in each groove adiacent the rim of the latter, the contact between the work and the groove gradually shifting to the center of the latter and then toward the opposite rim, so that the rolls contact spirally'with the work, and constantly shift-the contact between the work aand the roll transversely of the groove. Accordingly, the work does not bear the imprint of slight inaccuracies in the grooves in the rolls.

As has been above indicated, it is preferable 'to provide in such apparatus an adjustment of the mounting of each roll so as to make it possible to change the angle between each axis and the direction of travel of the work. In Figures 2, 4d and 417, I have shown in detail one manner in which adjustment of the roll pass may be eflected. It will be understood that this disclosure is applicable both to the sizing unit and to the smoothing and finishing unit, as will be evident from Figure 1. The upper roll i0 is Journaled in anti-friction bearings ll mounted in housings ll capable of vertical sliding movement along vertical tracks I9 on the edges of slots in a head 2|. The bearing housings it are resiliently suspended from the head 2| by bolts 22 supported by washers 23 on springs 24 received in recesses in the head 2|. A double wedge 28 slidable horizontally relative to the head 2| is operable by a screw 26 to simultaneously vary the vertical position of the housings ll along the tracks It.

The head 2i is provided with lower flanges 28 for supporting the same in adjusted position. In order to change the angle of the axis of the upper roll II, the bolts 29 are loosened to loosen the clamp II; and the head 2| can be revolved about the center of the roll pass to change the angle of the roll axis relative to the direction of travel of the work. It is apparent, therefore, that this arrangement of the appar'atus makes provision both for slightly raising and lowering the upper roll it, and also "for shifting slightly the angularity of its axis.

Asdriving motor 32 is connected through reucing gearing 33 to the outer end of a ,drive shaft M. The inner end of the drive shaft 34 onejend of theKshaft 36 which carries the up- |l., Similarly, a motor 38 is connected thrizaugh reduction gearing 39 tovthe outer end of a drive shaft ll whichis similarly connected through a flexible coupling 4| to one end of the shaft on which the lower roll "I is carried. The motor 38 and gearing are arranged so as to drive the lower roll it in the opposite direction from the upper roll Ill. The operation of the pair of rolls is to advance the material and at the same time impart rotation thereto about its own axis.

No vertical adjustment of the lower roll l is required as the spacing between the rolls can ter may be tightened to hold fast the flange 48 by means of bolts If the bolts 5i are loosened, the base 45 may be turned to adjust the angularity of the axis of the lower roll H).

In carrying out a sizing operation in accordance with my preferred practice, the material I is delivered to the apparatus as round bars or the like requiring a small reduction in cross-section. For instance, billets or other shapes may be passed through breakdown rolls and then through roughing mills, the material being passed back and forth through these roughing mills until the same has been rolled to a shape roughly approximating roundness. The material having been thus reduced roughly to the desiredcross-section, is stacked on the storage rack 8; and is then transferred one length at a time onto the tracks 9 for feeding into the sizing unit. After the sizing operation is completed the material passes into the smoothing and finishing unit which delivers the finished product onto the table IS. The sizing operation and the smoothing and finishing operation are both cold rolling operations; and the finished product exhibits a smooth and fairly bright surface, the latter approaching the truly cylindrical almost as closely as material which has been centerless ground.

In Figure 5 is shown a layout of sizing units for successively acting upon the material so that a substantial reduction in cross-section may be effected. The units a, b, c and d are adjusted to bring the rolls of each successive roll pass slightly closer together; and moreover, the angle between the travel of the work and the roll axes is increased for each successive sizing unit. The increase in this angle equalizes the speed of rotation of the material as it passes through the successive passes. In other words, the angle between thebar travel and the roll axes in each pair of rolls will be greater than the corresponding angle of the preceding pair of rolls.

An important feature of my invention is that rolling in the manner taught in this specification gives a true round. In contrast to the usual procedure of rolling between opposed grooved rolls having their axes substantally parallel, the material revolves in the pass between the opposed grooved rolls at the same time that it is traveling through the pass. allel axes are employed, the accuracy of roundness depends upon the true roundness of the groove in the rolls of the mill. When following the procedure taught herein, any part of the surface of the round comes in contact with varying portions of the groove of the roll l0, inasmuch as the material is revolving as it travels through the pass. In fact, if the grooves in the rolls Ill when first installed are not true, these grooves will wear accurately to the correct shape. It is obviously an advantage over former rolling practice to use rolls whose tendency is not to lose their accuracy but rather to become more accurate with wear.

'The use of opposed grooved rolls for simultaneously reducing the cross-section of material and for causing rotation of the material as it travels through the pass between the rolls simplifies the equipment necessary for rolling to an accurate round shape and size. At the same time, the cost of necessary equipment is substantially reduced. Moreover, the reduction of the cross section of the material simultaneously with the rotation of the material as it travels through the pass between the opposed grooved rolls improves the roundness of the material over that produced by ordinary grooved rolls mounted on parallel axes.

As the term "groove is used in the claims, the same is to be undl :stood as a term of description and not of limitation; and may be of such shape as is appropriate for the proper shaping of the round.

While I have described in detail a preferred embodiment of my invention and the preferred process of operation, it is to be understood that.

When rolls mounted on parthe invention is not so limited but may be other- 40 wise embodied and'practiced within the scope of the following claims.

I claim:

1. In a method of rolling substantially round material, the steps consisting in hot rolling bar stock approximately to size, then sizing the stock by a cold pass betweencross rolls acting along a spiral whose length is more than four times its diameter, and thereafter straightening the sized stock by a cold pass between cross rolls acting along a spiral whose length is about equal to its diameter.

2. The method of rolling substantially round material as claimed in claim 1 in which the cross rolls effecting the sizing of the stock are driven in opposite directions and the cross rolls effecting the straightening of the sized stock are driven in the same direction.

' PE'I'IER B. ABRAMSEN.

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