US3194044A - Rolled bars and method for manufacturing - Google Patents

Description

y 1965 N. H. POLAKOWSKI ETAL 3,194,044

ROLLED BARS AND METHOD FOR MANUFACTURING Filed March 14. 1958 2 Sheets-Sheet 1 FIG. Z FIG. 2

INVENTORS Na 511C olakowskz BY Za erzce fijcfmziii .242 form: 1 5

y 3, 1965 N. H. POLAKOWSKI ETAL 3,194,044

ROLLED BARS AND METHOD FOR MANUFACTURING Filed March 14, 1958 2 Sheets-Sheet 2 INVENTORS flaialzs liIPaZa/eowskz BY Lawrence 5,6'clmzzz'i MQ QZMWYM United States Patent 3,194,044 RGLLED BARS AND METHOD FOR MANUFAtJT'URlNG Natalis H. Poialrowski, Wilmette, and Lawrence B. Schmitt, Chicago Heights, Ill., assignors to La Salle Steel Company, Hammond, Ind, a corporation of Delaware Filed Mar. 14, 1958, Ser. No. 721,547

4 Claims. (Cl. 72-404) This invention relates primarily to the technological process for finishing metal, and more particularly to the reduction in the cross-sectional dimension of metal bars in the production of finished bars.

The invention which will hereinafter be described is applicable preferably to bars in the form of rounds, but many of the concepts are applicable to the finishing of fiats, squares, and the like bars of other continuous shapes. However, it can also be employed in related processes involving the production of semi-finished bars and sections.

To the present, one of the principal finishing processes for reduction in cross-sectional dimension of metal bars is effected by the process of advancing the bars through a die in a drawing or extrusion operation to work the metal while effecting a reduction in the cross-sectional area of the bars. Another commercial process resides in the advancement of the bars through a series of rollers arranged in pairs to effect a gradual reduction in crosssectional dimension with working until the desired dimension is reached in the final pass through the last of the series of the bars of roller dies.

In drawing, smaller sizes up to about -78 inch diameter steel bars and up to about inch in' diameter in softer, non-ferrous metals are commonly drawn on a machine known as a buP-blocii or bull frame and where the raw, hot rolled metal is advanced from coils and drawn through a fixed die with the aid of a powerful drum on which the reduced material is Wound. The finished metal is thus in the form of a continuous coil which is afterwards straightened and cut to suitable lengths.

Although somewhat larger sections than those indicated above are ocasionally processed in the form of coils, still larger sizes are too stiif for this purpose and they are drawn to the finished dimension on draw benches which normally accommodate bars up to about 30 feet in length. Each bar is drawn individually through a die to effect reduction in cross-sectional area. For feeding the bar to the die, its front end has to be either forced into and through the tapered portion of the die by the use of special retractable devices, usually hydraulically operated, or, in the alternative, the leading end portion of the bar has to be pointed in a separate machining or swaging operation to reduce the bar in diameter over a length up to about 1 foot in the leading end portion to enable the end portion to be freely inserted through the die so that its free end will project several inches beyond the other side of the die. A powerful, reciprocating gripper then engages the projecting end portion to pull the remainder of the bar through the die, thereby to reduce its diameter while increasing its hardness by working.

The draw process for metal reduction is intermittent and the substantial inertia of the reciprocating gripper carriage coupled with the relatively short length of the draw bench limits the miximum drawing speed to about 150 feet per minute. Since the carriage must return to its starting position after each draw, the actual average operating speed of these machines seldom exceeds about 190 feet per minute and is usually much slower.

The drawing process is thus considered to be relatively slow. It involves a certain loss of production from the standpoint of scrap since at least the front end portion of the bar which is marred by the gripper has to be cut off and discarded in the fabrication of the finished product. Further, the draw bench is not particularly well adapted for use in a continuous production line since the bars have to be transported over some distance from the pointing machines in advance of drawing and to the end trimming and straightening equipment after drawing.

For the present, cold rolling of bars has been found to be somewhat limited in its application. It is used mostly for the processing of bars of polygonal shape, such as square or flats, as in copper bars used as electrical conductors. Although rounds have been cold rolled for effecting reduction in cross-sectional area and for finishing, the process has been largely superseded by drawing, at least in the more recent period. The main reason for virtual abandonment of cold rolling in favor of drawing as a method of producing and finishing round bars resides further in the difiiculty in adapting the rolling process to the economical and efiicient manufacture of a rolled round of satisfactory shape and size tolerances while maintaining the bar sufficiently free from certain peculiar surface defects which the rolling operation is prone to introduce. The nature of these defects will become apparent from the following considerations.

In order to obtain a smooth surface and an nearly perfectly round cross-section, the fed bar had to be gradually reduced in sections by passage of the bar through a series of successive roll stands in which the axes of the rolls are preferably not parallel but instead are staggered with the axis of one stand being arranged at an angle of about with adjacent stands; otherwise it would be dificult to control the changes in cross-section as the bar is being reduced. Reduction is taken in such a way as to under-fill the grooves at all times with the intention of tapering off the degree of underfilling to the vanishing point towards the finishing or final roll stand. The ideal condition would be attained if in the last pass the metal were present in an amount exactly to fill the grooves but not to overfill the grooves, thus producing a section identical with the circular space formed by the grooves in the two mating rollers.

It will be apparent that his ideal condition can seldom be made available in a commercial operation. The reason is that both the cross-sectional dimension and the hardness of the hot rolled feed stock varies from batch to batch and even between individual bars within a single batch of material. These normal variations have serious repercussions in the rolling process.

Let it be assumed that a rolling mill has its rolls grooved to obtain a desired shape in finished bars at a predetermined screw-down setting with a hot rolled material of normal dimension and hardness. When a bar having even a slightly larger initial cross-section is advanced into the rolls, the rolls will be pushed apart and overfilling of the grooves will simultaneously occur. The excess metal will flow not only in the direction of rolling but it will also fiow sidewise into the space between the roller surfaces beyond the grooves. Thus, the issuing metal will not only exhibit an excessive cross-sectional dimension but it will also carry a flash or fin which extends outwardly from its opposite sides. On the other hand if the cross-section of the feed end is less than the nominal and the mill setting remains unchanged, a deficiency of metal will exist and the metal will be incapable of filling up the grooves and thus a product will be secured having two parallel lands or flats on opposite sides.

These lands will extend continuously along the bar.

This phenomenon will result in the production of bars which are out of round and generally undersized in the direction normal to the land surfaces. These three conditions are illustrated in FIGURES 1, 2 and 3 of the drawmg.

operation.

'3 V 2 Those skilled in the'art will appreciate that corrections of the roll pass adjustment in the finishing mill stand cannot compensate completely for size variations of this character. 'It will be appreciated further that making continuous changes in the large numberof successive stands would be impracticable in a mass production An additional objection levied against the rolling of rounds is to be found in the'fact thatin order to make 10 the'bars of various diameters, an extensive change of rolls is required each time that a size is changed. Sometimes asmany as from 3 to 10 or more roll'stands or passes are employed for size reduction and finishing.

In view of these adverse circumstances, rolling of round bars, especially of steel and other hard metals, has

been virtually abandoned in favor of the draw die.

Nevertheless, rolling represents a process which, in many respects, is basically more desirable than drawing because 7 FIGURE 7 is asectional elevational view through the bar taken along the line '77 ofFIGURE 4;

FIGURE 8 is a sectional view of the finished bar taken 7 along the line 38 of FIGURE 4;

FIGURE 9 is a sectional elevational view through the cut-elf section, and r it is capable of being adapted to a'continuous operation as distinguished from the intermittent operation of a' draw bench. Rolling can be performed at a much faster rate than drawing because of the absence of heavy reciprocat ing elements and mechanisms, and because the bar need not be pointed or otherwise especially: handled for advancement through the die nor especially. gripped by any kind of jaw or holder. In addition, the frictional losses in drawing are considerably higher than the frictional losses in rolling, such that less energy is expended per acter of the fins produced is such asto enable complete disposal of the excess metal and to enable clean and complete removal of the formed fins from the surface of the metal with a minimum amount of effort and preferably in anoperation which is continuous with the rolling operation to produce a finished bar of the desired crosssection. i j I It has been found that the dimensional accuracy de- Isired-can be obtained to a greater degree when rolling with flash to form rib's of a predetermined character, in

, 'accordance with the. practice of this invention, than when unit quantity of rolled metal products. 'It is evident that in order to make rolling practical as an operation for" finishing metal bars, and particularly massive metal bars, it will be necessary to provide means whereby variations in size, dimension and hardness will not interfere with the production of a clean, round, finished bar of the desired dimension free of fins and lands.

It is an object of this invention to produce and to provide a rolling method for producing smooth and round finished metal bars without fins and without lands independently of normal variations which may be expected to occur in the character and size of the feed stock.

' attempting to rollwithout flash. The shape and size of the fins that are formed are controlled by the contour of the rolls and preferably in such manner as to provide their narrowest dimension at the cut-ofi along the surface -of the rolled round so as to enable the removal of the fin cleanly and completely from the metal in cooperation with the last roll pass, and primarily as a function thereof to utilize the force available from the rolling step to adj i vancethe metal past the abrading or cut-"01f .knives by which the fins are removed without damage to the metal. ',;In accordance with the practice of this invention, the roll parts are constructed 'tojreceive any amount of ex- More specifically, it is an object of this invention to' provide a rolling process for size reduction and finishing of metal bars, especially rounds, which is not limited by tnormal variations in the size of the bars being fed; which is not limited by normal variations in, the character of the. metal being 'fed; which does not require additional steps in the preparation of the metal bar for rolling; which does not entail the-significant waste of. material in producing the finished metal bar; which is capable of being adapted for continuous operation; which does not produce a finished bar "having lands or ribs in the sides, and. which takes less energy to effect reduction by comparison with an equivalent reduction in a drawing operation. 7

These ,and other objects and advantages of this invention will hereinafter appear and for purposes of illustration, but not of, limitation, an embodiment of the inven-' tion is shown in the accompanying drawing, in which FIGURE 1 is a schematic cross-sectional view representing an ideal filling of the grooves of the rolls in a final pass;

FIGURE 2 is a cross-sectional view similar to that of FIGURE lillustrating overfilling with the resultant de-. 1' velopment of fins and with the resultant production of an oversized bar;

FIGURE 3 is a'sectional view similar to that of FIG-v URE 1 illustrating underfilling wherein lands .are formed by the unfilled portions of the grooves in the rolls of the finalpass;

arrangementshown in FIGURE 4;

FIGURE '6 is a sectional or FIGURE-4;

view taken along the line 6 6 I cess metal from the feed for disposition in the fin while maintaining the desired cut-off. After the last roll pass and cut-off, the metal can be advanced continuously or in'a separate operation through straightening rolls, alone V or in combination with a'polishing step, to obliterate any traces on the bar surface of the removal of the fin by cut-off or by scraping.

1 eHaving briefly set forth the concepts ofthis invention,

description will now be made of the practice of this invention in'processing a hot rolled steel bar by advancement of a barltl through a series of rollsIZ for efiecting. a reduction in cross-sectional area in a rolling operation to produce a product'14 of the desired size and with perfectly smooth surfaces.

The bar of hot rolled steel, having a dimension of 1 inch and a length of feet, is advanced continuously into a mill l formed of a plurality of cooperating bars of grooved rolls 12 arranged in tandem in the mill. A

pinching and/or feeding in' roller, represented'by the numeral '18, may be installed at the entrance end of the mill to'a'ssist the mill rolls in gripping the bar.

Asthe bar 10 is advanced between succeeding rolls 12 until it reaches the last roll Zt) which is grooved to 'the desired cross-sectionaldimension, 'and' which requires less metal in cross-section for filling than is in' the metal fed 'into' the last pass, a portion'of the excess metal which will not flow in the rolling direction will be caused to flash (iii laterally between the meeting edges 22 and 24 of the g "rollsections 26' and '28, respectively. 'The edges may FIGURE/4 is aside elevation'aliviewschematically illustrating the reduction of a metal bar by rolling in accordance with the teachings of this invention; 7

FIGURE 5 is a top plan view of a portion of the be intentionally spaced 'to permit such flow from the grooved portions of the rolls with the inner edge spacing 'being' designed to be of lesser dimensionthan theremainder to permit complete displacement of the excess 'metal into the-area between the roll parts and beyond the grooves. The excess metal'forms fins 30 extending outwardly from diametrically opposed portions of the finished metal bar issuing from the last roll pass with the inner end portion 32 of each of the fins being preferably formed to a considerably smaller thickness than the remainder to enable a more convenient removal of the fins by a scraping operation or by cut-off knives.

The shaving or side-trimming device 34 is mounted adjacent the exit end of the mill coaxially with the bar being rolled. The device may be fixed in any suitable manner to the mill delivery table or equivalent element. It will consist principally of a fixture in which side-trimming cutters or knives 36 are mounted with their cutting edges inclined towards the oncoming metal. The spaced relation between the cutting edges is adjusted to correspond to the diameter desired in the finished bar or the shortest distance between the bases of the fins 30 being removed.

It is desirable to' embody means such as set-screws 49 for adjustment of the cutters for a limited movement in the direction radially of the axis of the bar while employing resilient means such as springs or pneumatic or hydraulic actuating devices, to urge the cutters toward the bar surface or toward their inner position of adjustment.

The pressure of the springs or hydraulically actuated devices should be sufiiciently low to avoid scraping of the round surface of the bar, but sufficient to maintain the cutters in the desired adjusted position for removal of the thin flash.

It is desirable further to embody means within the cutter device to enable radial adjustment of the cutters in the direction toward and away from the axis of the bar for use of the cutters with finished bars of various diameters.

In view of the relatively small axial force required for advancing the bar through the trimming device, it is possible to make use of the forces normally made available by the mill itself, since the rolls are capable of exerting a sizable force on the bar in the direction of its movement. After emerging from the trimming device, the bar can be fed directly to a straightening or polishing machine installed at the end of the rolling machine, thereby to enable continuous operation for processing bars advanced through the elements in end-to-end relation.

Instead of arranging the trimming device as a continuous operation in alignment with the roll stands, the trimming or cut-off device may be located separate and apart from the rolling machine for removal of the fins.

Lubrication will present no problem by comparison with a drawing operation to achieve an equivalent reduction since the frictional forces are considerably less in rolling than in drawing and the surfaces of the rolls and of the metal bar are much more accessible. Thus, lubricant can be easily applied to the surfaces being worked and it can be collected for reuse in a conventional manner.

It will be apparent from the foregoing that means have been provided for effecting a reduction in cross-sectional area of round shafting in a manner which will substantially insure a product of the desired dimension notwithstanding variations which might be expected normally to occur in the dimension or in the hardness of the metal fed into the mill. It will be apparent further that the product that is secured will be free of flats or ribs which are characteristic of underfilling and overfilling, respectively, in rolling processes which have previously been employed.

The concepts described can be embodied in a continuous, low-cost operation because no special processing is required in the preparation of the bars for feeding to the roll pairs; the steps for reducing and subsequent shaving or deflashing can be arranged in a single integrated operation without any manual or even automatic auxiliary operations in between, and the bars can be advanced in end-to-end relation into the rolls for providing an uninterrupted line of bars in process.

It will be evident further that a number of other important technological advances have been made possible by the practice of this invention.

(1) The force needed to remove fins is so small as to enable utilization of any force capable of being provided by the roll pairs acting upon the bar during advancement therebetween, thereby to avoid the necessity for the use of special independently power driven removal means and equipment.

(2) The force required to cut off or remove the fins is so small as to require very little pressure on the tool normal to the bar surface, with the result that the removal means can be resiliently urged in the direction towards the bar to effect the desired engagement without objectionably marking the bar. This makes it possible to eliminate steps for defining the inner position of adjustment of the removal means since, under such circumstances, the work itself can function as the stop.

(3) Since the amount of metal in the portions of the fins 30 cut from the surface is so small in crosssection, use can be made of shaving tools having their cutting edges formed into concave sectors 42 of a radius of curvature not less than the radius of the bar and tangent to the latters surface and which can be oscillated or otherwise moved with respect thereto while remaining tangent to the bar surface at the root of the fin at all times.

(4) Scrap will be represented chiefly by the small amount of metal removed in the fins as compared to the substantial percentage that is removed or cut off in drawing and the much larger percentage resulting from imperfect bars in rolling operations which have previously been employed.

(5) Other processing equipment such as conventional straighteners and/ or polishers can be arranged in endwise alignment with the rolling means and removal means to operate with the reduction step as a continuous operation to produce a finished metal bar.

It will be understood that changes may be made in the details of construction, arrangement and operation without departing from the spirit of the invention, especially as defined in the following claims.

We claim:

1. The method of rolling metal bars to achieve a reduction in cross-sectional area comprising the steps of engaging the surfaces of the bars with a series of grooved rolls arranged in pairs to engage opposite sides of the bars as the bars are advanced linearly therebetween to effect reduction in the cross-sectional areas of the bars, engaging the opposite surfaces of the elongate bars with a final pair of grooved rolls defining a cross-section therebetween corresponding to the final cross-section of the bar with the lateral edges of the said final pair of grooved rolls having a spaced relationship therebetween which is a minimum at their inner edges and increases from the inner edges outwardly whereby the flash formed by the excess metal displaced by the grooved rolls extends outwardly from the opposite surfaces of the bar with a minimum thickness adjacent the surfaces of the rolled bar and with increasing thicknesses outwardly therefrom, and severing the flash from the bar at the point of minimum thickness adjacent the finished surface of the bar.

2. The method as claimed in claim 1 in which the means for removing the flashing is arranged in endwise alignment with the final roll pairs to form a continuous operation therewith.

3. The method of rolling metal bars to achieve a reduction in cross-sectional area comprising the steps of engaging the surfaces of the bars with a series of grooved rolls arranged in pairs to engage opposite sides of the bars as the bars are advanced linearly therebetween to effect reduction in cross-sectional areas of the bars, engaging the opposite surfaces of the elongate bars with a final pair of grooved rolls defining a cross-section therebetween corresponding to the final cross-section of the bar with the 'lateraledges of said final pair of grooved rolls having a spaced relationship .therebetween which is, a

minimum at their inner edges and increases from the .inner' edges outwardly whereby the flash formed by the .excess of metal displaced by the grooved rollsextends outwardly from the opposite surfaces of the bar with a minimum thickness adjacent the surfaces of the rolledbar and with increasing thicknesses outwardly therefrom,

and severing the flash from the'bar at the point 01 minimum thickness adjacent the finishedsurface of the bar ,and which includes the steps of straightening and polishthe last roll" pair with the thickness ,of thefins being naring the bars' after'the fiashinghas been removed and in a a continuous operation with the rolling and removal steps;

4.-In a machine for takin'ga reduction in cross-sectional area of a round bar ina'rolling operation having a plurality of grooved rolls arrangedin pairs in tandem and removal means aligned with the rolls for engaging the surfaces'of the bar upon issuance from the last roll pair to remove the 'fins, the improvement wherein the a last of the roll pairs is grooved to form a .circle'therebetween of the desired 'diameterfor the finishe'drbar' and .with a spaced relation between the meeting surfaces'of the roll pair increasing from a minimum at the inner edge I of the grooves to'a larger spaced relation outwardlythereof and into which the metal over and above thatneces-' sary to fill the grooves may HOW to locate the excess metal,

in fins extending outwardly from the bars issuing from rower at the surface of'the bar than in the remainder and in which the removal means is aligned with therolls for engaging the surfaces of the bar upon issuance from the last roll pair to remove the fins at the inner edge of thinnest c'Loss-section adjacent the surface'of the bar,

a and in which the; removal means comprises circular knife elements concentricallyarranged' about the outer surfaces of the bar, means constantly urging the knives in the'direction towards the bar, and means for moving theknive's in a circular path aboutthe bar. 1 r v h 7 References Cited hy the Examiner UNITED STATES PATENTS FVHITMOREA. WILTZ,1Primqry Examiner. NEDWIN BERGER, Examiner.

Claims (1)

1. THE METHOD OF ROLLING METAL BARS TO ACHIEVE A REDUCTION IN CROSS-SECTIONAL AREA COMPRISING THE STEPS OF ENGAGING THE SURFACES OF THE BARS WITH A SERIES OF GROOVED ROLLS ARRANGED IN PAIRS TO ENGAGE OPPOSITE SIDES OF THE BARS AS THE BARS ARE ADVANCED LINEARLY THEREBETWEEN TO EFFECT REDUCTION IN THE CROSS-SECTIONAL AREAS OF THE BARS, ENGAGING THE OPPOSITE SURFACES OF THE ELONGATE BARS WITH A FINAL PAIR OF GROOVED ROLLS DEFINING A CROSS-SECTION THEREBETWEEN CORRESPONDING TO THE FINAL CROSS-SECTION OF THE BAR WITH THE LATERAL EDGES OF THE SAID FINAL PAIR OF GROOVED ROLLS HAVING A SPACED RELATINSHIP THEREBETWEEN WHICH IS A MINIMUM AT THEIR INNER EDGES AND INCREASES FROM THE INNER EDGES OUTWARDLY WHEREBY THE FLASH FORMED BY THE EXCESS METAL DISPLACED BY THE GROOVED ROLLS EXTENDS OUTWARDLY FROM THE OPPOSITE SURFACES OF THE BAR WITH A MINIMUM THICKNESS ADJACENT THE SURFACES OF THE ROLLED BAR AND WITH INCREASING THICKNESSES OUTWARDLY THEREFROM, AND SEVERING THE FLASH FROM THE BAR AT THE POINT OF MINIMUM THICKNESS ADJACENT THE FINISHED SURFACE OF THE BAR.

Images