US2759301A

US2759301A - Method and apparatus for surface grinding metal strip

Info

Publication number: US2759301A
Application number: US368374A
Authority: US
Inventors: Le Roy R Valette; William C Safford
Original assignee: Crucible Steel Company of America
Current assignee: Crucible Steel Company of America
Priority date: 1953-07-16
Filing date: 1953-07-16
Publication date: 1956-08-21
Anticipated expiration: 1973-08-21

Description

LE ROY R. VALETTE ETAL I 2,759,301

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METHOD AND APPARATUS FOR SURFACE GRINDING METAL STRIP Filed July 16, 1953 16 Sheets-Sheet 3 mm IQUZb INVENTORS. LE/Po y/P. VALETTE BY VV/LL IAM C. SAFFOED.

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METHOD AND APPARATUS FOR SURFACE GRINDING METAL STRIP Filed July 16, 1953 16 Sheets-Sheet 4 INVENTORS.

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METHOD AND APPARATUS FOR SURFACE GRINDING METAL STRIP Filed July 16, 1953 16 Sheets-Sheet 6 lumullul l m INVENTORS. LEPoY 1?. l ALETTE.

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METHOD AND APPARATUS FOR SURFACE GRINDING METAL STRIP Filed July 16, 1955 16 Sheets-Sheet 9 INVENTORS. L: For A. Mqusrrzz. BY M/ILL/AM CSAFro/w.

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METHOD AND APPARATUS FOR SURFACE GRINDING METAL STRIP l6 Sheets-Sheet 10 Filed July 16, 1953 LJI v:

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METHOD AND APPARATUS FOR SURFACE GRINDING METAL STRIP Filed July- 16, 1953 l6 Sheets-Sheet l2 INVENTORSI :Por R. l/ALETTE. BY WILL/AM CSnrmea.

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Aug. 21, 1956 LE ROY R. VALETTE EAL METHOD AND APPARATUS FOR SURFACE GRINDING METAL STRIP Filed July 16, 1953 16 Sheets-Sheet l5 Ls .WLEfrE. BY VI/ILLIAM CYSxu-meo.

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ATTORNEYS.

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ATTORNEYS.

METAL STRIP l6 Sheets-Sheet 15 LE ROY R. VALETTE ETAL METHOD AND APPARATUS FOR SURFACE GRINDING Aug. 21, 1956 Filed July 16, 1953 IN V EN TOR-5'. VAL ETTE LIA M C.5Ar'raea.

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United States Patent -METHOD AND APPARATUS FOR SURFACE GRINDIN G lVLETAL "STRIP Le Roy R. Valette, Pittsburgh, and William 'C. Safiord, Industry, Pa., assignors to Crucible Steel Company of America, Pittsburgh, Pa., a corporation of New Jersey Application July 16, 1953, Serial No. 368,374

16 Claims. (Cl. 515) This invention pertains to improvements in grinding apparatus for the surface grinding and removal of surface defects from metal strip, such, for example, as long lengths of steel strip of sufiicient thinness to permit of coiling onto reels, and in widths which may vary from a few inches up to 50 or 60" or more.

In the hot rolling of a metal breakdown into long lengths of relatively thin strip, surface defects, such as slivers, are often produced as a result of the rolling operation. Such defects are not removed by subsequent pickling and cold rolling, but are carried through as surface defects of the finished cold rolled product. In the pro duction particularly of high grade alloy steel strip, such, for example, as the 18-8 chromium-nickel or the straight chromium staindless varieties, such as are employed for trim in the automotive, building industries, etc., it is essential that the cold rolled and finished product have a smooth, unmarred surface of high luster, entirely free from all surface defects. It is accordingly frequently necessary in order to obtain a surface of this character in the finished cold rolled product, that all surface portions of the hot rolled strip be subjected to roughing and finishing grinds, prior to finish cold rolling.

Grinding units heretofore employed for such purposes have in general been of the single-stand variety in which the strip is fed from a payoff reel between a pair of driven rolls, about one of which an abrading belt passes, the opposite roll serving as a backing up roll, thus to surface grind one side of the strip, which passes thence onto a windup reel. Grinding units of this character are expensive and cumbersome in operation due to the fact that each pass through the grinding unit requires unreeling and reeling the strip, and transporting the reeled unit back to the payoff reel for each successive pass through the grinder. Frequently a half dozen such passes are required properly to surface grind and finish each side of the strip, or a total of approximately a dozen or so passes in all.

In contrast to the above, the improved grinding apparatus of the present invention comprises a multiplicity of grinding units arranged seriatim, through which the strip is progressively and successively fed, from a payoff reel disposed at the entrance to the multi-stand grinding as sembly and thence onto a coiling reel at the delivery end thereof. in accordance with various aspects of the invention, the grinding units may be of the conventional abrading belt variety or may comprise a series of abrading rolls or a combination of abrading rolls and abrading belts, and may be arranged to surface grind one or both sides of the strip as it passes through the multi-stand grinding assembly aforesaid.

The initial abrading stands of the sequence may thus be arranged to provide roughing grinds and the remainder of the sequence, finishing grinds of varying degrees of impression, so that in a single pass through the multi-stand sequence, the strip is both rough and finish ground, and thus emerges ready for pickling and cold rolling. If both sides are surface ground concurrently, the strip need be unreeled and reeled but once; while if only one surface at a time is ground, only two unreeling and reeling operations are involved.

By the provision of a sufficient number of the grinding stands in sequence, for example, six in accordance with the preferred embodiment of the present invention, the abrading elements in certain of the stands may normally be disengaged from the strip while the remainder are grinding, so that in the event one of the stands which is effecting the grinding requires disengagement for repairs or for changing an abrading belt, one of the normally idle stands may be engaged during the interim, thus to assure uniformity in the grinding operation throughout the en tire strip length. The apparatus of the invention thus provides extreme flexibility of operation in this respect, and also in the respect that one, two or more or all stands may be caused to engage the strip during a given grinding operation, depending on the extent of surface grind-- ing required for that particular length.

Each of the grinding units, in the preferred embodiment thereof, comprises in tandem, a pair of entry pinch rolls, an abrading roll or contact roll carrying an abrading belt, together with an associated pressure roll, and an exit hold-down roll, these rolls being positioned for rotation about horizontal axes. To facilitate the threading of the leading strip end of a coil through the grinding unit, one of the pinch rolls is mounted for retraction with respect to its opposed pinch roll; and likewise the pressure roll is mounted for retraction with respect to its opposed abrading roll. After the strip end is threaded through the grinding unit, these rolls are advanced into their operative positions for resiliently pressing the strip against the opposed pinch and abrading rolls, respectively. In the preferred embodiment, this retraction and advance ment of the pinch and pressure rolls is rapidly effected by means of hydraulic cylinder and piston assemblies.

Also in the preferred embodiment the pressure and abrading rolls are disposed slightly above the pass line of the entry pinch and exit hold-down rolls, in order arcuately to flex the strip over the pressure roll, thus to provide a substantially tangential area of contact between the abrading roll and the strip surface contiguous thereto, thus to assure uniform surface grinding of all portions of the strip.

Fine or micrometer adjustments are provided in the mounting for the pressure roll of each grinding unit, for adjusting the same relative to the associated abrading roll in accordance with the thickness of strip being ground, and also for purposes of axially aligning the pressure roll, in absolute parallelism with the associated grinding roll. Various novel features are embodied in the mounting and adjustments of the pressure roll, as will more fully appear hereinafter in the detailed description relative thereto.

The entry pinch rolls of each grinding unit are further provided with disengageable braking means, for applying braking action thereto as the trailing end of a coil of strip being ground, passes off the payoff reel and successively thence through the grinding units, the so-braked pinch rolls serving thus to maintain tension on the strip between the successive grinding units and the windup or recoiling reel.

In the preferred embodiment there is also interposed between the payoff reel and the first grinding unit of the sequence, a levelling unit of novel construction, comprising a series of lower rolls, having opposed thereto in intercalated or staggered relation, a series of upper rolls, together with a pair of entry pinch rolls and a pair of entry guide rolls, the latter being rotatable about the vertical axes for centering the strip in the leveller. The opposed intercalated rolls serve to straighten the strip as it is fed therethrough. The upper levelling rolls are ar- Patented Aug. 21, 1956 ranged to beindividually elevated and depressed relative to their associated lower rolls, and the same is true of the upper entry pinch roll. The levelling and pinch rolls are arranged to be motor driven. For feeding an advancing strip end through the leveller and into the first grinding unit, the upper pinch and leveling rolls are depressed and all rolls are driven. After the strip is fed completely through the apparatus from the payoff reel onto the recoiling reel, the upper rolls of the leveler are either elevated away from the strip, or are thereafter arranged to function merely as idler rolls, since the power applied for driving the recoiling reel suffices to feed or pull the strip through the entire grinding line from the payofi? reel, and since also the resulting tension thus applied to the strip thereafter suffices for straightening or flattening purposes. For thus controlling the tension on the strip, the payoff reel motor is arranged for optional driving or regenerative braking, and is regeneratively braked after the leading strip end has been 'fed onto the recoiling reel and driving power applied thereto.

Other important features of the invention reside in special provisions for safety and operation and adjustment of the several units and for individual and integrated driving and control means for the several units, whereby efficiency and safety are greatly enhanced.

Further objects and advantages of the invention will more fully appear from the following description taken in connection with the accompanying drawings which show, by way of example, a presently preferred embodiment and certain modifications of the invention.

Referring to the-accompanying drawings inwhich the same reference characters indicate the's'ame parts in the various views:

Figures 1 and 2 jointly constitute a somewhat diagrammatic view of one embodiment'of the invention, showing the general arrangement of certain features 'of a grinding line assembly in side elevation and associated main control panel shown in plan view;

Fig. 3 isa side elevational View of the payotf (unit A) or reel uncoiler at the input 'or entry e'ndof the machine;

'Fig. 4 is an end elevational view'of'the unit shown in Fig. 3, as viewed from the strip reel end;

5 is a cross-sectional view taken at line S'-Sof Fig. 3;

Fig. 6 is a cross-sectional view taken at line 6- 6 of i Fig. f7is a somewhatdiagrammatic view showing the end of the strip passing from the coil of strip to the pinch rolls of the leveller;

Fig. 8 is a plan view and Fig. 9 '21 front end' elevation of the levellingunit B of theFigures 1- 2 apparatus;

'Fig. 10 is a longitudinal sectional elevation of line 10- 10 of Fig. 8; v

Fig. 11 is an enlarged fragmentary side' elevationof the Figures 8 and 9 apparatus, as viewed from the left in Fig. 8;

Fig. 11a is a cross-sectional view taken at =-line 11a11a of Fig. 11 showing further'details;

Fig. 12 is a plan view of one of the limit switches shown in Fig. 11;

Fig. 13 is a perspective view of one of the cams and mount of the Figure 11 limit switches;

Fig. 14 is a side elevation of one'of theg'rin ding units, such as C1, of Figure 1 with the housing'broken away to show the interior mechanism; while"Fig. '15 is a front elevation of the Figure 14 apparatus, again with'the housing in section to show the interior'con'struetion;

Fig. 16"is asectional plan as' taken substantially at 16-16of Fig. 14;

Fig. 17 is a sectional plan view as'taken substantially at 17-17 of Figure while Fig. 18 is a fragmentary end section as taken substantially at 18 18 of Fig. 17;

Fig. 19 is a longitudinal elevation ofthe'furne and dust removal system for the grinding units C1-C6 forming ll part of the apparatus shown in Figures l-2; Fig. 20 is a sectional elevational view taken at 20-20 of Fig. 19, and Fig. 21 is a fragmentary plan view of one of the fume ducts of the apparatus shown in Fig. 19, for removing fumes and dust from one of the grinding units;

Fig. 22 is a side elevational view of the windup (unit F) or recoiler at the output end of the machine;

Fig. 23 is an end elevational view of the unit shown in Fig. 22 as viewed from the drive and braking end;

Fig. 24 is a fragmentary side elevational view showing certain other features of said unit;

Figs. 25-28, inclusive, are somewhat diagrammatic side elevational views showing various alternative modifications of the grinding unit assemblies according to the invention;

Fig. 29 is a diagrammatic layout of the hydraulic control system of the apparatus, for actuating various hydraulic .piston and cylinder assemblies employed in the apparatus as described below; and

Fig. 30 is a corresponding diagrammatic layout of the direct-current electric control system of the apparatus, for controlling the various direct-current, energized motors, solenoids, etc., asdescribed-below.

GENERAL DESCRIPTION Referring now to the drawings and more particularly to Figs. 1 and 2: the apparatus therein comprises in general a payoff reel unit A, a leveller unit B, a sequence of six-grinding units individually designated C1C6, inclusive, arranged seriatim or :in tandem as shown, a scrubber D, a wiper unit'E and a windup reel unit F. In addition to these main units there are provided suitable electric, hydraulic and pneumatic motors, together with controls therefor grouped at stations located at convenient positions adjacent theentry end of the apparatus, 'at each grinding unit and at the deliveryend, all being integrated to facilitate operation. The control stations are disposed as follows: Main stations I and II are located adjacent the delivery and entryends, respectively, and a series of stations III are located adjacent respective of thegrinder units C1-C6, inclusive.

The payoff reel unit A comprises apayoft reel .22, for mounting a coil of-strip 23'on'the'rcel shaft, which is coupledto a motor Zlaoptionally operated as a motor or draggenerator, and thus adapted'eithcr to drive'or brake'the shaft. A blocker hoist 24-is provided. adjacent the payoff "reel shaft to facilitate"mountingit-hecoil..23 on the reel shaft as explained below.

Next in the sequenceisthe strip lcveller unit B-whieh comprises a: guide roll-29, a pair of spaced apart vertical centering rolls 30, an upper series 33 and a lower series 32 of'levelling rolls'between which the strip S'passes for straighteningzpurposes. These rollsare arranged to be'driven or'idled as desired at various-stages of-thc grinding operation, having associated therewith'for: such purposes adrive motor' el coupled to the rolls. Likewise, the upper series of ro'lls 33 are mounted in bearing blocks,

vertically displaceable in: guidewaysnbynmeansa 'of suitable electric motors43a to behe-reinafter described, for raising the upper rolls off the'strip' once it has been fed through the assembly 'line. Driven pinch= rolls 55-56 aref-provided for feeding the strip to the levelling rolls-and are separable by fluid motorsSS to permit free passage.

Next in the sequence is the series of grinding units C1-C6, each of which comprises in substance a :pair' of entrance pinchrolls, suchas 86'87,"between which the strip isfed, and the upper 'roll beingprovide'd with fluid actuated brake means to producea dragon the strip, and the lower roll being retractable, at certain conditions of operation; as above' mentioned. Beyond the pinch rolls, in the direction of the strip path, area pair of rolls 89 and 92, one of 'which'comprises' an abrading roll'or an abrading belt contact roll, su'ch as"92, the opposite roll 89 functioning as a backing up or, pressure roll. In certain modifications of the invention, the upper roll is the abrading roll or abrading belt contact roll, while the lower or pressure roll is arranged for vertical displacement toward and away from the strip, thus to be elevated and engage the strip during grinding, and to be dropped well below the strip pass line to facilitate feeding the leading strip end of a new coil through the grinding unit. At the exit of each grinding unit there is mounted a holddown roll, such as 91), the function of which in conjunction with the entrance pinch rolls 36-37 is to flex the strip arcuately over the backing up roll, thus to provide a tangential line of contact transversely of the strip between the strip surface being ground and the upper abrading contact roll engaging the same for grinding purposes.

The strip on emerging from the last of the grinding units, e. g., C5, passes thence through a scrubber unit D for removing grit, sludge, grinding compounds and the like from the strip, and thence through a wiper unit E for removing excess scrubbing fluid, from whence the strip passes onto a driven windup reel 184 on which the ground strip S is wound into a coil 186.

PAYOFF UNIT A Referring now to Figs. 3-6, inclusive, the payoff reel unit A comprises a main frame 21 and a motor-drag generator 21a suitably connected through a reduction gear train Zib-Zic to a reel shaft 22a for driving or braking a payoff reel 22. The payoff reel is of the conventional expansible segment type actuated by a conventional hydraulic mechanism 22be, inc, for expanding and gripping the coil 23 of strip S to be surface ground. Adjacent the payoff reel there is provided (Fig. 1) a coil hoist 24 having mounted thereon a pair of hoist blocker rolls 24a, on which the coil 23 of strip S is rotatably supported preparatory to mounting 011 the reel 22. The coil hoist is raised and lowered by conventional hydraulic ram and cylinder means mounted below the floor line as described below. Adjacent the coil hoist is an inclined ramp 26 provided with elevatable floor chocks (not shown) for rolling the strip coil 23 onto the hoist blocker rolls. By a conventional hydraulic means, such as cylinders 25, Figs. 4 and 6, and pistons, as at 25a, operating therein as shown, the reel 22 can be moved axially in and out to receive the coil 23 from the hoist 24, and to line the coil up with the grinding line equipment. To this end the entire coiler assembly is slidably mounted on wear plates. as at 25b. one on each side, and is axially displaced in and out by oil pressure and discharge lines interchangeably connectible through a 4-way valve, as explained below, to the opposite end, respectively, of

cylinders

25, 25, thus to displace these cylinders relative to their associated pistons, which latter are pin connected, as at 250, to fixed supports, as at 25d.

An important safety feature of the invention embodied in this unit is the provision of an arcuate arm 27 (Figs. 3 and 4) which extends in a direction transverse the axis of a coil 23 and disposed intermediate its ends. The arm 27 comprises side plates between which are pivotally mounted a main roller 27a adjacent its forward end, intermediate rollers 27b and 27c in spaced relation along the arm and a pair of rollers 27d on a rear extremity disposed beyond the axis of a torque shaft 27:? to one end of which the arm is fixed. The rollers 27a27d, inclusive, have their axes generally parallel to the axis of reel 22 and are spaced apart along an arcuate path preferably having a larger radius than the radius of coil 23. The rollers are so disposed that when roller 27a engages coil 23 the other rollers are progressively spaced from said coil while the strip is being fed forward and serve to res-train outward movement of a loose strip end. The shaft 27c is suitably journaled on the frame 21 and adjacent its opposite end carries fixed thereto a crank arm 27] to the outer end of which is pivotally connected a piston rod 27g of a pneumatic motor designated 27h. This motor is operated by a suitable control valve, to be hereinafter referred to, conveniently positioned at the entry end.

LEVELER UNIT 3 From the coil 23 (Fig. 2) the leading end of the strip S thereof is fed to the levellcr unit B. The latter comprises, as shown in Figs. 7-10, inclusive, an entry guide roll 2-9, disposed as shown, for engaging the strip S when the coil 23 becomes reduced sufficiently in diameter during the unreeling operation. At the entrance of the leveller there is also provided a pair of oppositely disposed and vertically arranged guide rolls (Fig. 9), such as 38', for centering the strip transversely in the leveller.

Guide rolls 30 may be adjustably spaced, in accordance with the strip width, and may also be adjusted right or left as viewed in Fig. 9, at constant spacing. To this end, the rolls are journaled to bearing blocks, such as 31a, which in turn are secured to yokes, such as 31b, these yokes in turn being suitably bored as at 310, for slidable mounting on

guide bars

31d, 31e. The yokes are also tapped as at 31f, for threaded engagement with adjusting

shafts

31g and 31h, respectively. These shafts are threaded in opposite directions, as shown, shaft 31g in fact constituting a sleeve member rotatable on an extension of shaft 31h extending therethrough as at 311. Keyed to shaft Zili is a hand wheel 31k while keyed to shaft 31g is a second hand wheel 31m. Thus, if the hand wheels 31k and 31m are rotated concurrently in the same direction, the guide rolls 30 will be displaced toward or away from each other, whereas if the hand wheels are rotated in opposite directions at constant speed, the guide rolls will be adjusted right or left at constant spacing, as viewed in Fig. 9.

The leveller B comprises in addition to the elements aforesaid (Fig. 10), a set 32 of three driven bottom rolls 32a, 32b and 32c journaled at their opposite ends in oppositely disposed stationary bearing blocks 32d and File (Figs. 10 and i1), and a set 33 of two driven top rolls 33a and 33b. The roller 33a is journaled in oppositely disposed end blocks (Fig. 11a) 34a-34a and the roller 33b is similarly journaled in corresponding blocks Mfr-34b. The blocks 34a34ib at one end of the rollers are held together in a horizontal direction but permitted relative vertical movement by means of a dovetail connection designated 35 and the blocks 34a-34b are similarly held together by a like connection 35. The connected blocks 34a34b and 34a'34b' are supported in aligned position and vertically adjustable in oppositely disposed end guides 36a36b and 36a36b', respectively. The

rollers

33a and 33b are individually movable up or down by mechanism now to be described.

The bearing blocks 34a-34a are adjustably supported by respective shafts 3737' (Figs. 10 and 11a) having threaded portions engaged in cooperating threaded bores provided in worm wheels, such as 39, which are in driven engagement with worms, such as 39a, secured to a worm shaft 41. The worm wheels 39a and shaft 41 are suitably journaled in stationary end frames 42a and 4211. Similarly, the blocks 34b34b' are adjustably supported on shafts 3838 cooperatively adjustable by means of worm wheels, such as a, driven by worms, such as 39a, secured to worm shaft 42. The

worm shafts

42 and 41 are respectively driven by

motors

43a and 43b (Figs. 8 and 10) to which they are suitably drivingly connected as by means of chain and sprocket drives 43d43f and 430-43e, respectively.

In order to facilitate the control of the raising and lowering of the bearing blocks 34a and 34b, means are provided for simultaneously energizing the

motors

43a and 43b to raise such blocks, the latter being automatically stopped under the influence of pairs of limit-stop switches 44 and 45 (Fig. 11). The

switches

44 and 45 are respectively provided with switch levers 44a and 4501 which carry pivotally mounted on their outer ends cam rollers 44b and 45b in the path of movement of cam members 46 and 47, respectively, which are secured to the bearing blocks 34a and 34b, respectively. The cams 46 and 47, for example, are of the wedge variety and are ver- 7 tically adjustable by suitable screws, whereby the actuation of

switches

44a and 44b may be properly timed.

Conversely, motors 43a and 431) are automatically stopped by the downward movement of the bearing blocks 34a and 34b, respectively, by analogous mechanism including switches 40 and 49 having respectively switch arms 48a and 4911,

cam rollers

43b and 49b and cooperating

cams

50 and 51, respectively. Such cams are likewise adjustable vertically for timing the actuation of the switches 43 and 49.

As is well shown in Figs. 10. 11 and 13, the earns 46 and 50 are adjustably mounted on a bracket 52 which is rigidly secured to the bearing block 34a for movement therewith and there being adjustment screws 53 and 54 for fixing the position of the cam 50 upon such bracket and similar adjustment means for cam 46. In a similar manner the

cams

47 and 51 are mounted on the bearing block 34b.

In addition to the aforementioned primary and secondary sets of leveller roll-s, there are also employed a pair of leveller pinch rolls (Figs. 7, 8 and 9), such as 55 and 56. The former is preferably mounted for rotation upon a fixed axis but the latter can be raised or lowered. The top pinch roll 56 is mounted in suitable bearing blocks, such as 5757. The latter can be raised or lowered by means of a power cylinder, as at 58, which may be actuated by any suitable fluid medium. Preferably there are two such cylinders 53, one for each side of the apparatus.

The sets of

rolls

32 and 33 and the pinch rolls 55-56 of the leveller unit are driven by means which will appear more fully below, for feeding the advancing strip end into the first grinder. When the strip gets into coiling position upon a winding reel, to appear hereinafter, the upper rolls are lifted to the position shown in Fig. 11 so as to clear the strip. The rolls of the leveller may or may not be continuously driven. Either the top and/or the bottom rolls can be power driven.

in the present embodiment the rollers of the leveller B (Fig. l) are all driven by an electric motor 62 (Figs. 3

and 4) which is connected by a suitable gear box 62a and shaft connector 621) to a reduction gear box 620 from which splined and universal jointed

shafts

62a, 62a and 62 serve to supply driving power to the three

shafts

32a, 32b and 326, and similarly

shafts

62g and 62h and 62i and 62 serve to drive the upper leveller rolls 33a and 33b and the pinch rolls 55--56, respectively. An electric motor 62l drives suitable lubrication means for supplying lubricant to the drive train of motor 62.

GRINDING (UNITS C1-C6) A typical grinding unit C1 is shown in Figs. 14l8 and will now be described. The strip is first directed between a pair of superimposed entry pinch rolls 86, 87. the upper of which is mounted in stationary bearing blocks, and the lower of which can be raised or lowered by a pair of suitable power cylinders, one for each end of roll 87, one of which cylinders is shown as at 88, actuated, for example, by pneumatic or hydraulic fluid. Power cylinders 88 communicate thrust to their respective bearing blocks 87a of roll 87 via piston rods 88a. In the modification shown in the drawings, no drive is applied to these pinch rolls. The web passes thence convexly over a bottom pressure roll 89, the top surface of which is somewhat above the bite of the pinch rolls 86, 87. Thence the web 27 is passed beneath a hold-down roll 90, the

rolls

86, 87, 89 and 90 being so positioned to cause the web 27 to travel convexly over the bottom pressure roll 89, thereby to present a convex surface substantially tangential to the opposed abrading element comprising in the modification, an endless belt 91 which is mounted to travel in a well known and conventional manner, upon three rolls consisting of a contact roll 92 which is opposed to and in vertical alignment with the bottom pressure roll 89, an idler roll 93 at the top of the three rolls, and a belt tension and takeup roll 94 which, in the form shown, is mounted upon one arm of a bell crank 95, the latter being centrally pivoted at 96. The outer extremity of the opposite arm 95a thereof is pivotally connected as at 99, to a piston 98, operating in a pneumatic cylinder, to thereby provide for automatic belt tensioning by pneumatic pressure continuously applied to the cylinder and thus to the piston. (Selective belt oscillation is provided as by an oscillating cylinder 80 and oscillation adjustment 81.) Thus, the danger of stretching the belt edges is substantially eliminated thereby adding greatly to the belt life.

The contact roll 92 preferably consists of a metal core having a rubber or rubber-like covering. The other rolls 93, 94 may be similarly covered if desired, but in the form shown are not.

In order to assist in controlling the tension of the strip 5, the pinch rolls 86, 87 are provided with suitable brake means in the form shown comprising a friction brake having a brake shoe for the top roll 86, as at 100, and a shoe for the bottom roll, as at 101. Suitable hydraulically actuated means may be employed for controlling the pinch roll braking means comprising, for example, a power cylinder and piston device, as at 102, having a piston rod 103, which pivotally engages a brake arm 104. The latter is operatively connected with the aforementioned brake shoes and 101. The pinch roll brakes are applied when the trailing end of the strip or web is about to clear the payoff reel. The tension upon the web can thus thereafter be maintained until the trailing end passes the last grinder. Two such braking means, one for each extremity of roll 86, may be employed.

A four-way valve 97a is provided for controlling the actuation of the power cylinder 97. As will be more particularly pointed out hereinafter, suitable manually controlled valves are provided respectively for controlling the braking of the top pinch roll and also for raising and lowering the bottom pinch roll; pressure meters are provided for indicating the pressure between the pinch rolls 86, 87 and also the pressure upon the pinch roll braking means; a pressure meter is provided for indicating the pressure on the bottom pressure roll 89.

The bottom pressure roll 89 is mounted for angular movement about a pivot, as at (Fig. 14). Means are provided for quickly disengaging the bottom pressure roll 89 from the strips comprising, a pair of oppositely disposed arms 106 pivoted on the aforementioned pivot point 105, said arms supporting a pair of bearing blocks 1.07 for supporting opposite extremities of the bottom pressure roll 89. Quick disengagement of the rolls 89, 92 is obtained by means of a knee type toggle linkage, indicated generally at 108 (Fig. 14) and comprising upper and

lower links

109 and 110, there being a

pair

109, 110 for each side of the apparatus. Referring to Fig. 15, it is seen that the link 109 comprises two parallel side plates 109a and 1091; of equal lengths secured at their extremities by pins which hold the same rigidly in spaced relationship. The upper extremities of the links 109 are pivotally secured, as at 111, to a yoke 107a which supports the bearing block 107. The lower extremities of links 109 are pivotally associated at the knee by means of pins, such as 112, with which the connection is made with the lower links 110 Whose lower ends are pivotally secured, as at 113, to eccentrics 114 (Fig. 18). The angular movement of such eccentrics raise or lower by equal amounts opposite extremities of the bottom pressure roll 89 by means of the linkage 108.

The eccentrics 114 preferably are formed integrally, one on each end of shaft 117 which is drivingly connected to a geared electric motor 118 (Fig. 15) through the intermediary of the following interconnection: A chain and sprocket drive 1180:, a shaft 119, a worm and wheel unit 120, a shaft 121 having therein a universal joint 122, and a second worm and wheel unit 123.

A rapid disengagement of the rolls 89, 92 is effected

Claims

1. IN AN APPARATUS FOR SURFACE ABRADING AN ELONGATED STRIP OF METAL, THE COMBINATIION OF: A PAYOFF REEL FOR ROTATIVELY SUPPORTING A COIL OF SAID STRIP; MEANS FOR DRIVING SAID PAYOFF REEL TO UNWIND SAID STRIP; LEVELLING MEANS ADJACENT SAID PAYOFF REEL FOR RECEIVING THE LEADING STRIP END FROM SAID COIL AND FEEDING SAID STRIP FORWARDLY WHILE LEVELLING THE STRIP; A TANDEM ARRANGED SERIES OF GRINDING UNITS FOR SUCCESSIVELY RECEIVING SAID LEADING STRIP END; EACH SAID GRINDING UNIT INCLUDING IN TANDEM, A PAIR OF ENTRY PINCH ROLLS, A DRIVEN ABRADING ROLL AND OPPOSED PRESSURE ROLL, AND A HOLD-DOWN ROLL, MEANS FOR RETRACTING SAID PRESSURE ROLL RELATIVE TO SAID ABRADING ROLL