US2227789A - Rotary tin plate shears - Google Patents

Description

Jan. 7, 1941., w. w. MAGFARREN ROTARY TIN PLATE SHEARS INVENTQR.

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Jan. 7, 1941.

W. W. MACFARREN ROTARY TIN PLATE sHEARs Filed June 2, 1936 5 Sheets-Sheet 2 om mn wa mm MQ @ma /mz/W 5 Sheets-Sheet 3 Filed June 'l 2.. 193s i 1122.122212 :III: Yi

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Jan. 7, 1941.

W, W. MACFARREN ROTARY TIN PLATE sHEArvfs Filad June 2, 1936 5 Sheets-Sheet 4 Patented Jan. 7, `11.941

UNITED STATES PATENT OFFICE ROTARY TIN PLATE SHEABS Walter W. Macfarren, Los Angeles, Calif. Application June 2, 1936, Serial No. 83,174

15 Claims. (Cl. 164-68) My invention relates to rotary shears, and may be used for the automaticA shearing of any material in the form of thin sheets, webs. or strips, as for instance, paper, card board, brass, aluminum,

or steel. The present invention is specifically designed for the shearing of rolled steel tin plate stock, or tin plate, from coils.

The machine is designed to shear strip steel from 12" to 32" in width, and of gauges from i0 .007" to .015", and to cut therefrom sections of any fractional lengths between the limits of 12" and 48", and varying by as little as .005".

The speed of operation may be varied from 100 ft..per minute (feed) or less, to 2000 ft. per minute, or more, depending on the length of the cut sections, as will hereinafter appear.

In previously issued patents for rotary ilying shears, I have shown machines designed to operate with the peripheral speed of the knives substantially equal to the linear speed 'of the strip being cut. This'isy synchronous operation.

In Patent No. 1,994,107, I have shown special electrical and mechanical controls for synchro,- nizing the above named speeds. In various other co-pending applications, particularly Ser. No. '73,790 andvSer. No. 96,501 I have shown rotary shears using various degrees of asynchronism, or -unequal speeds between the knives and the strip,

to a limited degree.

Inthe present invention, due to the thin material to be operated on, and its light weight and flexibility, I make us/e of this asynchronous meth- Vod to a considerable degree. 'I'he present invention also makes use of a loop" between the primary and the secondary feeding means, in a man ner similar to my co-pending application Ser. No. 96,501, except that here the primary feeding means is a leveller. The present invention also makes use of pinch rolls of varying radius for varying the feed of the material, in a manner similar to those shown in my co-pending application Ser. N0. 96,501.

The present invention also makesl use of multiple shear knives as shown in my co-pending ap- 45 plication Ser. No. '13,790 but in this case the knives are all rigidly mounted on the shear drums, and used in a novel manner to cut Vsections of diiiere'nt lengths as will appear later. In the drawings,

Fig. l is an end elevation of the shear proper.

Fig. 2 is a plan view of the same partly in section, and with the upper portion omitted.

Fig. 3 is an elevation, partly in section, of the receiving side of the machine.

55 Fig. 4 is adiagramA showing the coll, the leveller, the loop, the pinch rolls, the shear drums,

v and the receiving and discharge conveyors.

Fig. 5 is an venlarged vertical section through the 'pinch rolls and the knife drums. 5

Fig. 6 is a diagram of. the drive for the discharge rollers. i

Fig. 'l is an end view of a special knife gauge, and

Fig. 8 is a table or data sheet showing the various cuts, speeds, feeds, gears, et cetera. 'lo For a preliminary general survey, referring to Fig. 4, the strip 2 is drawn from the coil i by the leveller 3, which may be of any usual construction, and which should be driven by its own variable speed motor. The guides or chutes 4 extend l in a reversed curve from the last leveller rollv to the lower end of a belt conveyor 5, comprising the upper 4pulley 5, the lower pulley 1, the intermediate idler pulleys 8.. and the belt 9.

The pinch rolls Ill are adjacent to the pulley go t, and the shear drums I5 and 20 carry the cutting knives 40. '111e cut sections are discharged by the knives onto the small rollers 2l. and from thence pass on to a conveying belt 25. The belt conveyor 5 is preferably driven from the leveller l, and the operation will be described in more detail later.

The base of the machine is a bed plate i8, upon which are mounted two housings 30 and 35, which are secured to the bed plate is by root nous ls. 3

Each of the housings 30 and 35 is provided with accurately aligned upper and lower bores 22, in which are mounted the main roller bearings 23 for the knife drums I5 and 20.

The housings 30 and 35 are of the general form 35 of an elongated 0 and have nobearing boxes, the bearings 23 being rigidly mounted directly in the bores 22. This construction is rigid, economical, and accurate.

The knife ydrums i5 and 2li may be duplicates 0 except as to length and are preferably made of forged steel with integral trunnions, and accurately machined all over. Both drums l5 and 20 are provided with extensions 26 to carry the connecting gears 2l, which maf have straight spur teeth as shown, or may be of the construction shown in my cov-pending application Ser. No. 73,790 with double helical teethand special means for eliminating backlash.

The gears 21 are each keyed to their drums, 50 and clamped by a nut 28 against a spacer 29, as shown. Outside the nut 28 on the upper drum I5, there is mounted a pulley y wheel 3| to be driven by a belt.

For the speciiic design of machine illustrated in the table Fig. 8, two pairs of cutting knives are used, both pairs being used when cutting sections from 12" to 24" long, and only one pair being used when cutting sections from 24" to 48" long.

It is obvious however, that for a larger machine, or even for the design shown, four pairs of knives might be used to advantage, and in Fig. 5 I have so shown it. For vthe present ma-V chine, the use of four pairs of knives would enable the machine to cut sections synchronously down to 9" long, and asynchronously down to 6" long.

For a machine of say twice the size, and having four pairs of knives, sections could be cut from one foot to eight feet long, using the principles of action herein described. In Fig. 5 the diameter of the knives from tip to tip is 11% (the gears 21 having the same pitch diameter). The knife periphery is therefore 36.14", butin the table Fig. 8 I have used an even three feet.

Each knife 46 is mounted in a milled slot 32, these various slots being exactly parallel to the drum axis both radially and longitudinally. The

knives 46 are made of hardened steel and ground on both sides 33 and 34, and on both edges 36 and 31 (Fig. 7).

'I'he edges 36 and 31' are oppositely beveled as shown, an amount suicient to keep them within the circle described by their cutting Aedges (or corners). The slots 32 are slightly wider than the knives 46, so the latter will enter easily. The cutting side 33 of the knives 46 is always set against the working side 38 of the slots 32, so that if the slots are accurately formed, as they must be, the cutting edge of each knife is exactly registered with the axis of its drum.

The knives 46 are held in the slots 32 by a line of hollow set screws 4|, there being 12 of these for each knife as shown in Fig. 2. These set screws remain permanently in place, and can be tightened or loosened by a half turn. Clearance spaces 43 are milled for the set screws 4|.

The bottoms 42 of the slots 32 are bevelled to t the edges 36 and 31 of the knives 46, and small liners 44 are used to position the knives radially. These liners 44 will vary in thickness to suit the variations in knife width caused by wear and'grinding, and in Fig. 7 I have shown a gauge |36 suitable for determining this thickness. This is simply a, hardened steel bar having a groove which correctly fits the assembly of knife and liner. Knives and liners thus gauged will ilt the drums exactly, without` adjustment, and therefore the knives may be quickly changed, or applied.

Reverting to Fig. 2, the gears 21 are enclosed by a casing 46 secured to the housing 35. The bearings 23 are held by retainers 41 and 48, and bronze washers 49 are secured to the ends of the drums I5 and 26, and bear against the inner retainers 41. The upper drum I5 is mounted to prevent endwise motion in its bearings, and the lower drum 26 is mounted to permit a slight motion endwise.

A variable speed Amotor 45 is mounted above the machine, and rests on a pair of square tubular members or beams 56, which extend from housing 36 to housing 35 .and are secured to both of them. The motor 45 is preferably an exact duplicate of the leveller motor for reasons which will appear later, and has a pulley 5| which drives a belt 52 engaging the pulley 3|. A pair of idler pulleys 53 also engage the belt 52, and are mounted on pins 55 supported by a bracket 54, which 1n turn is secured to the beams 56.

It is to be noted that in operation, the motor 45 is set by usual controls for a desired speed, and that the knife drums I5 and 26 rotate at a substantially constant speed at all times when cuts are being made.

The pinch rolls I6 each comprise a tubular shaft 56, a drive member 51 for the. same,l two end collars 58, three intermediate spacers 59, and four or more pneumatic rubber tires 6|. The tires 6I are of the doughnut variety, as made for airplanes and small cars, and a size close to the size given herein is commercially available. The shafts 56 are mounted in ball or roller bearings 62, which are held in sliding boxes 63, which latter are adjustable vertically in guides 64 formed in the housings 36 and 35.

The boxes 63 are adjusted toward or away from each other by four screws 65 and 66, in such a manner that the surfaces of the tires 6I which contact the strip 2 are maintained at a constant level with reference to the knife drums I5 and 26. In other words the delivery of the strip from the pinch rolls is at a constant level.

There are two sliding boxes 63 for each housing 36 and 35, one for the lower and one for the upper pinch roll |6. Each box 63 has two threaded openings or integral nuts through which the screws 65 and 66 pass, and for each box 63 these threads are right and left hand. For the upper box 63 of housing 36 (Fig. 2) the near threads are R. H. and the far threads L. H. For the ylower box the near threads are L. H. and the far threads R. H. 'The screws 65 and 66 are threaded to correspond. e

A pair of brackets 61 connected by ribs 66 are secured to one of the beams 56, and beneath each bracket 61 there is secured a bearing box 12 containing two helical gears 69 and a worm 1|. One of the gears 69 is mounted on each of the upper ends of the screws 65 or 66, and the worm 1I engages both gears 69 and is mounted on a shaft 13 supported in bearings 14 in the boxes 12. Each gear 66 is held by a nut 16 so that the weight of the pinch rolls I6, and the sliding boxes 63, is hung on the screws 65 and 66. The worm 1I and the gears 69 may be R. H. or L. H., as convenient.

The left end of the shaft 13 is supported in a bearing bracket 11 mounted on the upper section of the gear box 66, and an indicator 16 is provided, to register with graduations on the face of the hand wheel 15. By the above described mechanism, the pinch rolls I6 are moved toward or away from each other in such a way as to change their working radii R in Fig. 5.

This action results in more or less of the strip 2 being fed to the knives 46, as will be readily understood. Applicant believes that the feeding action will be directly proportional to the radius -of the upper drum I5, and a fourth shaft 83 directly below the shaft 62. The right Vend 0f shaft 86 is inserted in a counterbore 84 in the left trunniony of drum I5, and keyed thereto. Its left end is supported by a bearing 35. The shaft 8| is supported in bearings 66. The shaft 82 is tubular and is mounted in bearings 81. Theshaft 88 is also tubular and moimted in bearings 88.

'I'he pinch `rolls I8 are driven from shafts 82 and 83 by spindles 88. Each spindle 88 has a small integral spur gear 19 at each end.

I'he right end of each spindle 88 `engages a driving member 51 in one of the-tubular shafts 58, the said member lbeing provided with internal gear teeth loosely engaging the teeth of the gear 18 on the spindle 98. 'Ihe member 51 is keyed or otherwise secured to the shaft 56 to drive it. A similar drive member 88 is loosely set in the left end of each shaft 82 and 88, and these members 89 have a square end 9| which may engage a square hole 82 in a plate 98, secured by bolts 94 to a flange 95 on each shaft 82 and 83.

By this arrangement, the spindles 88 are of ample length to give the required vertical adjustments of the pinch rolls I8, and are concealed and out of the way. s t

The shaft 88 carries four spur gears A, C, E, and G, all loosely mounted ,on the shaft, and driven bylaw clutches 86 and 91, which latter are keyed to shaft 88 and are shifted by shifters (not shown) on the vertical shafts I8| and |82, which are in turn operated respectively by levers |85 and |86. (Fig. 3.)

Similar clutches 88 and 88, are mounted on the hollow shaft 82, and operated from similar vertical shafts |83 and |84.

The shaft 8| carries seven spur gears B -M- D-K-F-I-H, all keyed to the shaft. The shaft 82 carries four spur gears N-L-J-I88. Theshaft 83 carries a gear I I8 of equal size to the gear |88, and which meshes with,` and is driven thereby, so that the two shafts 82 and 88 always rotate at the same speed, andl in opposite directions to drive the pinch rolls I8. v These gears have the following dimensions:

Gear No. Diam. Pitch L symbol teeth pitch diam. R'P'M Speeds Y Inches 80 8 10 100.00 60 8 7% 133.33 58 6 9% 100.00 47 6 7% 123. 40 57 6 9% 100.00 48 6 8 118.75 54 46 `9 100.00 5l 6 8% 110.00 53 8 6% v 27 g lg 81. @-75. 117-72. 20--67.0lr

1 Z9 g gig/ 102. 12b-95.2741. 70-84.94

0 70 8 8% 133.33-1Z!.40118.75-110.00 66 6 1l G6 6 11 With the shear drums i2 and 28 assumed to run at 5100 R. P. M. the gears ACE and Gr will have the same speed, and the shaft I8| will run at l33.33-l23.i0-118.75 or 110 R. P..M., depending on which gear is driving. The above four speeds may be transferred Idirectly to the pinch roll drive shafts 82 and 83, by means of equal 'gearsthe equal gears M and N, and the H80 and iiil. v

The idylle primary speeds above may also be reduced ay' the gears K and r. to 102.95-952'1-9mo and 882.04 P.` M. for shafts 82 and 83. And also, these speeds may be reduced by the gears I and .l to 81.22-15.17-7228- and 67.01 R. P. M. As shown there are thus available twelve speeds for the pinch rolls I8, varying by gradual steps from 67.01 to 133.33 R. P. M.

As shown bythe table Fig. 8, the differences motor.

in these speeds from step to step are covered ^by the variations in' the working radius R of the pinch rolls I8, so that in effect, any speed may be had between 67.01 and 133.33 R. P. M. Or, in other ywords, the correct rate of feed for the strip 2 may be obtained to cut sections from 12" to 48" long, -as shown by the table.

At the delivery side of the machine I provide a pair of brackets III and ||2 secured respectively to the housings 38 and 35, and which may be connected by integral ribs H3, as indicated in dotted lines in Fig..1. The brackets III and II2 carry the shaft Ill and its pulley IIS. They also carry the small discharge rollers 2|, and the driving rollers ||6 therefore, and one end of the shaft |28. V

Thedrlving rollers I I6 are short-about 4" face (see Fig. 2) and are provided with rubber rings or sheaths II1, which bear against the small rollers 2| and drive them. 'I'he rollers II6 are in turn driven by a pair of rollers I|8 on the shaft |28, the same having rubber sheaths IIS,

- which bear against and drive the covers ||1 of rollers H8.

The shaft I 28 passes through the housing 38, and carries a small sprocket |2| at its left end (Fig. 2), which may be driven from a. sprocket 'I per minute when the knife drums I5 and 28 rotate at 180 R. P. M., in order to insure a free discharge of the cut sections. 1

'I'he belt conveyor 25 is similar to the one covered by my cci-pending application Ser. No. 96,501 and may be driven from its delivery end, or from a point between its This conveyor may be operated in three different ways, as follows: l

1. At the same speed as the delivery rollers 2|, which will deliver the cut sections side by side, without overlap. 'I'his is not advised.

2. At a slow uniform speed, say 1A to l/l" advance for each section cut from the strip, which will deliveru the sections overlapping.

3. With alternate stops and starts. During the new coil is being set in place (or at other times), the conveyor belt 25 can be advanced enough to leave room for a new pile, or the pile just formed can be. movedto a :desired point. This is the preferred method.

At 823 in Fig. 3 I have shown an oil pump which may bevdriven by gears |24 from the shaft 83 to pump oil to a reservoir |25, resting on the beams 58, andfrom which gravity oil feeds may be led to all points requiring lubrication.

Referring to the table Fig. 8, column 1 shows the lengths of the cut sections by inch steps, col. 2 shows the distance travelled (circumferentially) by the knives during the intervalsfgbetween cuts, or per cut, co1. 3 shows whether one or two pairs of knives are in use, col. 4 shows the asynchronous travel of the strip in inches or the amount the strip travels less (minus), or

ends by a separate stops the sections will form a pile, and when a per minute, at these. speeds, col. 9 shows the gears in use to give the pinch rolls the proper speed for the section lengths vbeing cut. col. 10 showsthe corrp nding R.. P. M. of the pinch rolls, col. 11 shows the advance of the strip to the knives in feet per minute, col. 12 shows whether the knives exert ai pull or a check on the passing strip, col. 13 shows the amount of this pull or check in thousandths of an inch, and col. 14 shows the eective diameter of the pinch rolls, or twice the working radius R of Fig. 5. The diameter is used as being easier to visualize.

Especial attention is directed to columns 12, 13, and 14, which show the guiding principles of the present invention. It is obvious that for a heavy rotary shear cutting heavy strip steel at high speeds, the strip speed and the knife speed should be substantially the same at the instant of cutting. If this is not so the cutting (feeding) speed must be reduced considerably. Generally speaking, asynchronism is bad. It is also obvious that for thin light sections, some degree of asynchronism-may be successfully used, even at high speeds, but the table Fig. 8 is the iirst time these conditions have been expressed in readily understandable figures, as far as applicant knows.

A machine designer can get more information from this table in a short time than he can obtain from pages of description.

In order to obtain the data in cols. 13 and 14, the following constants for this machine (as previously assumed) are used.

The maximum thickness to be cut is .015" (gauge). Assuming the cut is completed when the knives are at the vertical center line of the drums l5 and 20 as indicated in Fig. 5, the cutting angle, or the angle between the vertical center line and a radius drawn to the point where the knivesiirst grip the strip (when .015" apart) may be computed from the known thickness, and the known knife radius.

For .015" gauge and 5%" knife radius, the cutting angle is three degrees. The cutting chord, or the distance from the point of knife grip to the vertical center line is .30". The retarding chord (check) is double this, or .60" as the knives must open .015" after the cut is made, to let the strip pass on.

Now it will be evident that with synchronous knife and strip speeds, there will be neither a pull nor a check Such conditions are shown in the table Fig. 8 for 10" and 36" cut sections. And also, for a minus asynchronism, that is, the

strip moving at a lesser speed than the knives, a

pull will beproduced. The amount of this pull will be the constant cutting chord of .30" multiplied by the percentage of asynchronism. For a 12" cut this is .30X331/3% or .10".

Similarly for a plus asynchronism, the amount of the check will be the retarding chord of .60" multiplied by the percentage of asynchronism. For a 48" cut this is .60X331/3% or .20".

From this it will be seen that the percentage of asynchronism determines the maximum speed at which the shear may be successfully operated, which is just another way of repeating that these speeds should not be too far apart. However, a percentage, of asynchronism which would be im'- possible, or very undesirable on thicker material, may be freely and successfully used on such light -material as is now under discussion, because the cutting angle, and the cutting and retarding chords increase rapidly with increase in thickness.

Regarding speeds, there is no apparent reason why, a shear of this design, cutting sheet steel of .015 gauge, will not operate smoothly at 2000 feet per minute when making synchronous cuts. as 18" or 36". For a 15" cut the pull is only .05", and for a 2l" cut the check is only .10". Similarly, for a 30" cut the pull is only .05, and for a 42" cut the check is only .10".

It is probable then, that sections'from 15" to 21" inclusive, and from 30" to 42" inclusive, may be cut almost as fast as for synchronous cuts. It is also probable that the other cuts tabluated which are outside this range, may have to be made at somewhat lower speeds, but for .015 gauge applicant believes a minimum speed `of 1000 feet per minute can be successfully used throughout the range of the table Fig. 8, of from 12 to 48".

AS shown in Figs. 1, 3, and 5 the path of the strip 2 between the Vpinch rolls I0 is at a level a little above the path of the strip between the knives 40. This setting is purposely made to constrain the strip 2 to travel in a slight reverse curve or non-rectilinear path between these points. When a pul1" occurs this reverse curve is straightened somewhat, and also the amount of play or torsional looseness between the driving ends of thespindles and the members 51 and 8S, is purposely made such that the periphery of the pinch rolls I0 may be freely advanced by the pull on the strip, without affecting any other parts. The amount of this play should be at least $41".

It is to be noted that the amount of the pull given in the table Fig. 8, column 13, will never be fullyrealized, because the strip will separate when cut about the way through, and this action will be assisted by the pull. While the check is double -the amount of the "pul1 for the same percentage of asynchronism, its effect" is practically negligible for thin material, as the strip 2 will merely bend or bow a small amount to take up the extra length. This bending action will be assisted and assured by the curved path of the strip between the pinch rolls andthe knives, as previously described.

However, `for a larger machine of the same type, and one to cut thicker material, I prefer to use la curved guide or guides, as indicated in dotted lines at |26 in Fig. 5. The upper curved surfaces of these guides constrain the strip 2 to take a slight initial bend before the cut occurs; and during the out, if a "checking" cut, this bend is merely increased to an amount sufficient to absorb the check.

Reverting now to Fig. 4, the koperation is as xfollows, assuming the vspeeds of the leveller and the shear to have been previously adjusted to a desired relation. The shear runs at as near to a constant (set) speed as its motor 45 will drive it, and the pinch rolls I0 run at an equally constant but different speed determined by the selective gears A-B-(B, etc.

The leveller 3 being in motion, the end of a coil of strip 2 is fed to it, and this end passes out and slides down the curved guid 4 until it is engaged by the belt 9, which carries it uphill and between the usual adjustable side guards- |21 to the pinch rolls I0. i ,A

At this time the roller is depressed and the circuit controlled by it through wires |28 and |29 is closed. This circuit leads to the armature of the leveller motor,.and includes enough resistance to cut down the set speed of the leveller motor from 3% to 5%.

When the pinch rolls I0 engage the strip 2, it

is fed to theknives and cut, and the loop I 3 in the strip 2 gradually rises to its lower level Il, and then to its normal or average level I 3, and

iinally to its high position I2, at which point or a' little above it, thI roller II is raised, the aforesaid resistance is t out, and the leveller motor speeds up to normal speed to drop the loop.

'Ihe loop I3 is thus automatically maintained by these slight changes in speed oi the leveller motor. In this connection, this loop could be dispensed with by the use of the special synchronizing controls covered by my Patent 1,994,107, but for a small machine I prefer the arrangement herein shown.

It will be noted that the power required by the leveller and by the shear is so small and so nearly equal that their motors may be duplicates. It is further evident that the same branch mains could supply both motors. Therefore the variations in line voltage would be the same, and would aiect both motors alike, and as' the loads on both machines are practically uniform (due to shear iiy wheel 3l), these two motors could probably be' made to run at speeds within 3% of each other, by the usual field resistances.

At the higher operating speeds it might be necessary or desirable to slow down both .the leveller vand ,the shearwhile a new strip was entering the pinch rolls. For this purpose a joint control ofthe two motors could be used.

It .will be understood that very fine adjustments as to the lengths of the cut sections may be obtained by manipulation of .the hand wheel tilt 15, which controls the working radii R of the pinch rolls. It lis of course evident that any lengths of cut sections between the inch lengths shown in .the table Fig. 8 may be obtained in this way, and it will be also evident that if the pinch rolls I 0, at the start of a table division,

as say 35'K', are too large to make an intermediate cutfof say 35%", the next geared speed can be used, as for a 36, cut, and .the working diameter of the pinch rolls reduced `from 11.13" to the dimension necessary. As previously shown, additional geared speeds may be easily incorporated in the design. v

In regard to the durability of the pneumatic tires 0i on the pin'ch rolls I0, 1000 feet per minute feed of the strip 2 is equal to 11.4 miles per hour. At .this speed, and for the light duty required, the tires 0I should give 20,000 miles of service, which is equal to 1754 hours, or 220 -hour days, or about a years service, as it is not probable the shear could be kept in constant operation at this speed. The foregoing description` is believed` to fully cover the present invention, and to show .that a machine constructed in accordance therewith is comparatively simple, and may i very accurate, reliable, and durable. Where sizesdimensions, gear ratios, or other similar data are given, it will be understood that such data is assumed, and given for illustrative illlliwses only, and is subject to wide variation to meet the conditions imposed by any speciiic design.

i claim as my invention:

i.` In a rotary shear for making transverse cuts on moving material in-'rthe form of a strip, a pair of equal diameter rotary knife carrying drums mounted on'xed centers and geared together, cutting mives carried thereby, means for feeding the strip .to the knives, means to drive lthe yieeding means to feed the stripv synchronously to the mecd of the knites, and other means to drive .the feeding means asynchronously to the speed of the knives.

2.I 'I'he combination of la leveller, a rotary shear in tandem relation thereto, and having cutting knives adapted to make transverse cuts on strip material fed to it by the leveller, a pair of variable speed pinch rolls for feeding the material .to the cutting knives. and means for forming and maintaining a, loop in the material between the yleveller and the said pinch rolls, the said loop being automatically controlled by variations in speed of the leveller.

3. In a rotary shear for making transverse cuts on moving material in the form of a strip, a pair of rotary knife carrying drums mounted on iixed centers and gearedtogether, cutting knives carried thereby, a pair of pinchrolls each provided wi'th one or more pneumatic rubber tires for 'contacting the strip and feeding the same to the knives, and means for varying the working radius of .the said pneumatic tires to vary the length of the strip so fed.

4. In a rotary shear for making transverse cuts on moving material in the form of a strip, a

pair of rotary knife carrying drums mounted on iixed centers and geared together, cutting knives carried thereby, a pair of pinch rolls each provided with one or more pneumatic rubber tires for contacting the strip Aand .feeding the same to tl'ie knives, and means for varying the working radius Aoi.' Ithe said tires to varythe length of strip so fed, comprising a screw down mechanism which may be operated to bring the pinch rolls closer to, or further from each other.

5. In a rotary shear for making transverse cuts on moving material in the form ofa strip, a pairl of rotary knife carrying drums mounted on iixed centers and geared together, cutting knives carried thereby, a pair of pinch rolls each provided with one orl more pneumatic rubber tires for contacting ,the strip and feeding the same to the knives, means for varying the working radius of the said .tires to vary the length of the strip so fed, in combination with a set of selective gears for varying the speed of the pinch rolls. L

6. In a rotary shear for making transverse cuts on moving ,material in the form of a strip,` a pair of rotary knife carrying drums mounted on fixed centers and geared together, cutting knives carried thereby. a pair of pinch rolls for feeding .thematerial to the knives, ,and a gear box containing four shafts, the iirst'shaft being driven at the same speed as the knife carrying drums, and the second shaft being driven from p a pair of rotary knife carrying drums mounted` on ixed centers and geared together, cutting knives carried thereby, a gear box containing selectively operated gears, a pair of final shafts in ytflrefsaid gear box, a pair'of pinch rolls for feeding the material to the cutting knives, and a spindle connecting each of the said nal shafts Vwith one of the saidpinch'rolls to permit of bodily adjustment of the latter.

' 8. In a rotary shear for making transverse cuts on moving material in the form of a strip, a pair of rotary knife carrying drums mounted on fixed centers and geared together, cutting knives carried thereby, a gear box containing selectively operated gears, a pair of hollow shafts in the said gear box, a pair of pinch rolls for feeding the material .to .the cutting knives, the said pinch rolls each being mounted on a hollow shat, and

, a spindle connecting each of .the hollow shafts in the gear box with one of the said hollow pinch roll shafts, the said spindle having most of its length within the said two hollow shafts.

9. In a rotary shear for making transverse cuts on moving material in the form of a strip, a pair of rotary knife carrying drums mounted on fixed centers and geared together,`cutting knives carried thereby, a series of small rollers adjacent to the knife drums and below thepdelivery point of the knives, a shaft driven from one of the said knife drums, and frictional driving connections between vthe s'aid shaft and the said rollers.

10. The combination with a leveller, of a' rotary shear arranged to receive the material as fed to it by the leveller, and cut it transversely into desired length sections, means for starting a loop in Ithe material between the leveller and the shear comprising a descending guide or chute to receive the material from the leveller, an inclined bel-t conveyor for receiving the front end of the strip from the said chute and carrying it to the shear, and means for automatically maintaining the said loop when formed.

Y 11. In a rotary shear for making transverse cuts on moving material in the form of a strip, a pair of rotary knife carrying drums mounted -on fixed centers and geared together, cutting knives carried thereby, a belt conveyor arranged to receive the cut sections as discharged by the cutting knives, and an intermittently opemtable drive for the said conveyor, whereby the belt may be stopped to allow the cut sections to form a pile thereon, and then started to convey the said pile to a desired point of discharge.

I.12. In a rotary shear for making transverse cuts on moving material in the form of a strip, a, pair of rotary knife carrying drums mounted on fixed centers and geared together, cutting knives carried thereby, a pair of pinch rolls for feeding the strip to the cutting knives, a gear box for driving the pinch rolls at variable speeds to vary the rate of strip feed, an elevated oil reservoir, and an oil pump within the gear box and driven by one of its shafts to keep the said reservoir supplied with oil, from whence it may be fed by gravity to point-s requiring lubrication.

13. In a rotary shear for making transverse cuts on moving material in the form of a strip, a pair of rotary knife carrying drums mounted on fixed centers and geared together, cutting knives carried thereby, and means for feeding the strip to the cutting knives comprising the combination of pinch rolls, speed varying gears to drive the same, Ithe said pinch rolls having continuous unbroken outer driving surfaces for all adjusted radii, and means' for varying the radii of the said pinch rolls by smaliamounts so as to .produce cut sections varying in length by a few thousandths of an inch.

14. The method of operating a rotary shear having a plurality of pairs of rigidly attached coacting shear knives, consisting in feeding the material to be cut to the knives with a degree oi' asynchronism proportioned to the numberof pairs of knives in use, in order to cutoff sections of desired length. A

15. The method of operating a rotary shear having two or more co-acting pairs of detachable shear knives, to cut olf sections of desired length from amoving strip, comprising the use of a single pair, or a plurality of pairs, of knives, feeding the strip to the knives with a degree of asynchronism to produce the cut lengths desired, and rotating the knives at a speed in proportion tocthe degree of asynchronism used.

WALTER W. MAOFARREN.

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