US3774271A

US3774271A - Sheet guiding and width-control apparatus

Info

Publication number: US3774271A
Application number: US00067383A
Authority: US
Inventors: F Depuy; N Santore
Original assignee: Mount Hope Machinery Ltd
Current assignee: Mount Hope Machinery Ltd
Priority date: 1970-08-27
Filing date: 1970-08-27
Publication date: 1973-11-27
Anticipated expiration: 1990-11-27

Abstract

Apparatus for guiding an indefinite length of sheet or web material, such a cloth, in a predetermined path, and also for controlling the width of stretchable material. In one form, a pair of scroll rolls are driven at differentiable speeds in response to the lateral positions of one or both edges of the sheet, to guide it laterally into a desired path and to retain its proper width. For guiding non-stretchable material, one roll is driven at a predetermined speed, and the speed of the other is controlled by the position of one edge of the sheet. A guider control system is also provided in which the exhaust rate from fluid-operated motors driving a pair of rotatable sheet-stroking means is adjusted by edge-sensing means to control the relative speeds of the rolls. This control system can also be used with selvage uncurlers of a rotary disk type. Another guider control system employs a constant-speed motive means to drive one or both sheet-stroking means through variablespeed drive means at relative speeds controlled by the sheet-edge sensing means. The drive means may comprise variable-speed transmissions or clutches.

Description

1 1 SHEET GUIDING AND WIDTH-CONTROL APPARATUS Inventors: Francis A. Depuy; Nicholas T.

Santore, both of Taunton, Mass.

Assignee: Mount Hope Machinery Company,

.laem n M ss Filed: Aug. 27, 1970 Appl. No.: 67,383

[52] US. Cl 26/66, 26/63, 226/15 [51] Int. Cl D06c 3/06 [58] Field of Search 226/15, 16, 17; 26/63, 66; 60/67, 105

[56] References Cited UNITED STATES PATENTS 1,678,925 7/1928 Tackaberry 226/15 1,680,190 8/1928 Wikle 226/15 2,123,064 7/1938 Rosch 60/67 2,124,339 7/1938 Schellens 60/67 UX 2,144,550 1 1939 Sheppard 60/67 x 2,688,176 9/1954 Birch, Jr... 26/63 2,823,443 2/1958 Umstott 26/63 3,022,235 2/1962 Brown et a1. 60/105 X 3,243,978 4/1966 Gowin... 26/63 X 3,419,944 1/1969 Santore 226/15 X FOREIGN PATENTS OR APPLICATIONS 1,867 1867 Great Britain 26/63 Nov. 27, 1973 Primary Examiner-Robert R; Mackey Attorney Rich and Ericson [5 7 ABSTRACT Apparatus for guiding an indefinite length of sheet or web material, such a cloth, in a predetermined path, and also for controlling the width of stretchable material.

In one form, a pair of scroll rolls are driven at differentiable speeds in response to the lateral positions of one or both edges of the sheet, to guide it laterally into a desired path and to retain its proper width. For guiding non-stretchable material, one roll is driven at a predetermined speed, and the speed of the other is controlled by the position of one edge of the sheet.

A guider control system is also provided in which the exhaust rate from fluid-operated motors driving a pair of rotatable sheet-stroking means is adjusted by edge-sensing means to control the relative speeds of the rolls. This control system can also be used with selvage uncurlers of a rotary disk type.

Another guider control system constant-speed motive means to drive one or both sheet-stroking means through variable-speed drive means at relative speeds controlled by the sheet-edge sensing means. The drive means may comprise variable-speed transmissions or clutches.

8 Claims, 9 Drawing Figures AlR SUPPLY f? employs a I 5 Sheets-Sheet 1 Patented Nov. 27, 1973 I 122129323153 3 FRANcrs A. D E P01 Mano: I 51041035 & fig avvegs Patented Nov. 27, 1973 3,774,271

5 Sheets-Sheet 2 FRANCIS A. Dz w NlcuousTisAu-rone 39 M g 22km fliibflizeys Patented Nov. 27, 1973 1 3,774,271

5 Sheets-Sheet 3 Izwezzi'ln sz FRANCIS A.DEPUY NlcuoLAsT SAN-rose y M &m

fli'i ozfizeys 5 Sheets-Sheet 4 Patented Nov. 27, 1973 m2 Ohm MGM 1220 31202 FRANCIS A. spew Nlcuousl'snn'rani @WQ 3Q Patented Nov. 27, 1973 v 5 Sheets-Sheet 5 I zweni'ow: Fnmcls A. D2901 NwncmsT smron M X SHEET GUIDING AND WIDTH-CONTROL APPARATUS BACKGROUND AND BRIEF DESCRIPTION OF THE INVENTION US. Pat. No. 3,419,944, issued Jan. 7, 1969 to Nicholas T. Santore for Combined Web Guider and Selvage Uncurler," and assigned to the same assignee as this application, describes and claims guiding apparatus which is especially useful for handling fragile or stretchable goods which must not be subjected to heavy longitudinal tension. That apparatus employs selvage uncurlers of the rotary disk type, which comprise pairs of opposed inclined wheels with interengaged circular rows of teeth. Two uncurlers engage opposite edge portions of a traveling length of sheet material, and are driven independently by a pair of variable-speed motors to control the relative amounts of lateral pull that the uncurlers exert on the sheet. The uncurlers are normally driven at equal speeds while the sheet continues in its proper path. The lateral positions of each edge of the sheet are detected by sensors, which act through speed control means to decrease the relative rate of rotation of either uncurler toward which the sheetmay tend to wander, with the result thatthe lateral pull toward the uncurler is reduced. Since the other uncurler maintains its normal speed it exerts a greater pull and restores the sheet to the normal path and proper width, at which time the uncurlers are caused to resume equal speeds.

The control system described by US. Pat. No. 3,419,944 employs bleed valves to control independently the pressure supplied to the two air motors, and thus control their speeds. The sensors are fingers which rest against the opposite edges of the sheet, each controlling the rate of bleeding from one of the valves according to the position of a corresponding edge. Although this system functions satisfactorily, there are two respects in which improvement is desired. First, an increase in the load imposed on the motors by the sheet, as for example by a change in the feed rate or back tension of the sheet, results in a substantial drop in uncurler speed. Secondly, the air bled from the system by operation of the controlling bleed valves does no useful work, and is wasted.

It is the general object of the present invention to improve sheet guiding and width-control apparatus of a type which acts to regulate the position and width of the sheet by controlling the relative speeds of a pair of rotatable stroking means, such as disks or rolls, which engage opposite edge portions of the sheet. Further objects and advantages of the invention will appear as the following description proceeds.

According to one aspect of the present invention, the stroking means are driven by fluid motors which are supplied with fluid at a predetermined pressure; their relative speeds are controlled by valves which affect the rate of fluid exhaust from the motors, and which are adjusted by edge-sensing means. In applications to stretchable sheet material, I may use sensing means at both edges of the sheet, to control independently the exhaust rates and thus the speeds of two variable-speed motors each driving one of the sheet-stroking means, thereby not only to guide'but also to control the width of the sheet. In guiding non-stretchable material, however, only one edge can be guided, and I prefer to drive one motor at aconstant speed, and control the other motor through a single sensing means and exhaust valve.

The individual exhaust valves are fully opened when the controlling sheet edge is running inward from its proper path, so that the corresponding motor has a minimum exhaust restriction, and runs at its top speed. This affords the sheet-stroking means a maximum of outward lateral pull on the sheet, causing the errant edge of the sheet to return to the proper track. To limit the top speed of the motors, l prefer to interpose adjustable throttling valves in the fluid exhaust conduits. A shift of a sheet edge outwardly from its path causes the sensing means to progressively close the corresponding exhaust valve, slowing the driving motor to reduce the outward lateral pull of the corresponding sheet-stroking means, and thereby permit the edge to draw inwardly to the proper track.

A particular advantage of the improved control system is that it tends to maintain a more uniform motor speed as the load imposed on the sheet-stroking means by the longitudinal cloth tension varies. This is the result of controlling motor speed by adjusting the rate of fluid flow, as opposed to adjusting the pressure of the fluid supply; an increased load merely raises the pressure drop across the motor, and therefore increases the driving torque to compensate, with no substantial loss of speed. Another advantage of the system is that all of the pressure fluid supplied to the system passes through the motor and performs. useful work, improving the cost efficiency of operation of the guider.

According to another aspect of the invention, a novel sheet guider incorporates a pair of scroll rolls, corresponding to a scroll roll of a type which is known per se, but divided into two parts. These rolls are driven at controllably-difl'erentiable speeds to guide the sheet by exerting variable opposed lateral pulls upon it. It is conventional to form a scroll roll by wrapping the surface of a cylinder with wire helices which have opposite threads on the two ends of the roll; and to rotate this roll against the surface of cloth in order to spread it laterally, and also improve its feel or hand by flexing it. I drive two divided scroll rolls in the' same direction of rotation but at differentiable speeds, under the control of sheet edge-sensing control means which adjust the speed ratio of the rolls in a manner to guide the sheet, and to control the width of stretchable sheet material.

According to still another aspect of the invention, control of the relative speeds of a pair of rotatable sheet-stroking means is obtained by driving one or both of them through van'able-speed drive means comprising variable-speed transmissions or clutches. The speed ratio of one or two variable-speed transmissions, or the engagement of one or two clutches, is controlled in response to the edge sensing means. In one form, an edge-sensing finger is arranged to control a valve, which regulates a fluid pressure acting on a servomechanism connected for adjusting a variable-speed transmission, or which controls the engagement of clutches. In another form, the edge-sensing finger is arranged to engage alternate contacts corresponding to edge-position deviation limits, thereby selectively to energize an electrical pilot motor which controls the speed ratio of a transmission, or selectively to control the engagement of clutches.

DESCRIPTION OF THE DRAWINGS While the specification concludes with claims particularly pointing out the subject matter which we regard as our invention, it is believed that a clearer understanding may be gained from the following detailed description of preferred embodiments, referring to the accompanying drawings, in which:

FIG. 1 is a fragmentary view in elevation, and partially in section, of a first form of the improved guiding apparatus;

FIG. 2 is a sectional end view of a portion of the apparatus;

FIG. 3 is a sectional view on an enlarged scale of an edge-position sensor and exhaust valve forming a part of the apparatus of FIG. 1;

FIG. 4 is a view in elevation of a pair of scroll rolls forming parts of the apparatus of FIG. 1;

FIG. 5 is a schematic plan view of a second form of the guiding apparatus;

FIG. 6 is a fragmentary view in elevation, and partially in section, of another form of the improved apparatus; 7

FIG. 7 is a schematic view of an alternative spee control system;

FIG. 8 is a schematic view showing another alternative speed control system; and

FIG. 9 is a fragmentary view in elevation of another embodiment.

Referring to FIGS. 1-4, a first form of the guiding apparatus includes a pair of scroll rolls 100, 102, each of which comprises a hollow cylinder wound with a

wire helix

105 or 106. The rolls are partially wrapped by an indefinite length of web or sheet material 104, which is fed in the direction shown by the arrows in FIGS. 1 and 2 by other means (not shown), forming portions of any conventional processing range in which the improved guider is to be used. The

helices

105 and 106 have opposite threads on the two rolls, so that when rotated in the same direction as the sheet moves, each helix tends to draw the sheet laterally outwardly in opposition to the other. For rolls intended to rotate in the illustrated direction, the roll 100 has a right-hand thread helix, while the roll 102 has a left-hand thread helix.

The

rolls

100 and 102 are supported on an axle 108, which extends in a direction normal to the length of the sheet and is rotatably mounted in stationary bearings 111 near its ends. The ends of the roll 102 are affixed by a pair of annular disks 110 upon the shaft 108, and one of these disks is keyed at 1 12 to the shaft. The roll 100 is free to rotate on the shaft 108, being supported at one end by a disk 113, and at the other by an attached drive collar 114, in which

bearings

116 and 118 are secured by retaining rings 120. The disk 113 may provide a plain bearing as shown, or may include a roller thrust bearing. Thrust is applied axially to the roll 100 by means of a compression spring 138, acting between a cup 140 mounted on the shaft 108 and a disk 142 at one end of the collar 114. Thrust bearings may be provided to reduce the friction applied by this spring loading arrangement, if desired.

The collar 114 has a drive sheave 122 secured to it by a set screw 125. The roll 100 is driven by a variablespeed air motor 124, or other fluid motor, through a sheave 126 and a drive belt 128, which is trained around the sheave 122. The shaft 108 has a sheave 130 secured to one end, and is driven by a variable-speed air motor 132, or other fluid motor, through a sheave 134 and a belt 136. The speed ratios of both belt drives 128 and 136 are the same, so that the speeds of the

rolls

100 and 102 will be in the same ratio as those of the

motors

124 and 132.

The

motors

124 and 132 are supplied with air pressure through a branched conduit 144, in which an ad- 5 justable pressure-regulating valve 146 is placed. An exhaust conduit 148 extends from the motor 124 through an adjustable-orifice valve 150 for the purpose of limiting the maximum speed of this motor, and thence through an exhaust control valve 152, which is shown in detail in FIG. 3. Similarly, an exhaust conduit 153 extends from the motor 132 through an adjustableorifice valve 156 to limit the maximum speed of this motor, and thence through an exhaust control valve 154 which is identical with the valve 152. The

exhaust valves

152 and 154 are supported on a transverse bar 156, and the spacing between them is adjustable by means of hand-cranks 158 and 160 to accommodate sheets of various widths.

Referring to FIG. 3, one of the exhaust control valves 152 is shown in detail. The valve includes a block 162 having a threaded bore 164 for mounting the valve. A hollow housing 166 is affixed to the block for mounting the remaining elements. The exhaust conduit 148 extends through a passage 168 in the valve block into communication with a bleed passage 170, whose outlet area is controlled by a conical valve element 172. This element is borne by an edge-sensing finger 174 adapted to engage one edge of the sheet material 104. The valve element 172 is flexibly mounted on the finger by means of a compression spring 190 to permit the element to seat accurately even though there might be some misalignment between the finger and the bleed orifice. The finger 174 is provided with mounting ears 176, which are pivotally supported on cone points 178 threaded into the housing.

In the illustrated form the finger 174 is biased toward the edge of the sheet 104, and away from seating engagement of the valve element 172 in the bleed passage 170, by means of a tension spring 180 secured at one end in a rivet 182 mounted on the finger. The remaining end of the spring is received through an opening 184 in an adjusting screw 186, which is threaded through a block 188 affixed to the housing 166. The screw 186 may be set to apply an amount of tension to the spring 180 appropriate to the width and stiffness of the particular sheet material being processed. However, as the air pressure in the exhaust orifice tends to open the valve by unseating the element 172, it may be satisfactory to omit the tension spring and rely solely on this exhaust pressure to bias the finger against the edge of the sheet.

The edges of the sheet 104 are shown in FIGS. 1 and 3 in normal position, in a desired track. Under these circumstances, the valve element 17 2 of each

valve

152 and 154 assumes a normal position, controlling the rate of exhaust from each of the

air motors

132 and 124 so that they run at a normal rate of speed. This speed is set by the regulating valves such that the

rolls

100 and 102 are driven with a linear surface velocity somewhat in excess of the rate of sheet feeding, perhaps 10 to 20 percent greater. This causes the rolls to exert a moderate and equal lateral spreading action on the goods, sufficient to hold it to the proper width and to remove any wrinkles that may develop. Because of the helical configuration of the roll surfaces, an increase in the speed would apply additional lateral spreading action to the goods, tending to pull the edges outwardly, while a reduction in speed would allow the edges to relax and contract in an inward direction.

Assuming that the left edge of the sheet 104 tends to shift to the right in FIG. 1, the finger 174 of the valve 152 will tend to tilt clockwise as seenin FIG. 3, increasing the area of the exhaust orifice 170. This will increase the speed of the motor 124 and the roll 100, tending to draw the left-hand portion of the sheet toward the left, and thus restore the left edge to its original track. In the event that the deviation of the left edge toward the right was occasioned by a decrease in the width of the goods, a similar increase in the speed of the motor 132 and the roll 102 will be instigated by the valve 154, and this will correspondingly draw the right-hand portion of the goods toward the right. Thus both edges will be drawn outwardly to their original tracks, and the width of the cloth will consequently be held to the proper dimension. If, on the contrary, the displacement of the left edge of the cloth to the right was occasioned by a bodily motion of the goods to the right without a change in width, the right edge will pivot the finger 174 of the right hand valve 154 in a direction to reduce the area of the exhaust orifice leading from the motor 132, correspondingly reducing the speed of this motor and of the roll 102. This reduction in the speed of the roll 102 relative to that of the roll 100 will allow the sheet to be drawn bodily to the left as seen in FIG. 1, without changing its width appreciably, until it is returned to the proper track.

Thus it will be seen that the exhaust control valves 152-and 154 act independently to hold the two edges of the sheet individually in their proper tracks, so that the apparatus serves both to correct lateral bodily displacements of the sheet as a whole, and also to correct deviations in width.

Because the speeds of the motors of the apparatus are controlled by adjusting the rate of flow of motive fluid from them, rather than the supply pressure, variations in the load imposed by the tension in the goods 104 do not substantially change the speeds of the motors. An increased loadresults in an increase in pressure drop across the motors, which tends to compensate by increasing their torque output and thus maintaining their original speeds. Correspondingly, a reduction in tension load reduces the pressure drop across the motors and the torque declines accordingly, to hold a uniform speed. There is normally some variation in the applied tension in many processing operations, and if this is allowed to cause a substantial variation in the speeds of the scroll rolls, random variations in the width of the goods would result.

An application of the same edge-responsive control system is shown in FIG. 5, in which a guider employs selvage uncurlers 14 like those described by the aforementioned U.S. Pat. No. 3,419,944. Each of these uncurlers comprises a pair of opposed wheels between which the sheet 104 passes, and of which the front ones carry circular rows of radially-extending teeth 16, while the rear wheels have similar rows of teeth 12 intercalated between the teeth 16. These teeth are formed of a flexible material such as rubber. The wheels are mounted in brackets 36 for rotation on axes which are inclined laterally and longitudinally of the sheet 104, in a manner to engage the

teeth

12 and 16 around limited arcuate sectors, which are centered at about the points y in FIG. 5. The teeth, rotating as shown by the arrows, first interengage at a point somewhat inside the edges of the sheet approaching the uncurlers, and disengage near the departing edges.

The speed of rotationof each uncurler 14 governs the amount of lateral pull that it applies to the sheet 104. The front wheels of the uncurlers are driven by the

fluid motors

124 and 132, and the lower wheels are driven by the interengagement of the

teeth

12 and 16, so that both wheels of an individual uncurler run at the same speed. The

motors

124 and 132 are supplied in common with air or other working fluid by a branched conduit 144, the pressure being controlled by a regulating valve 146 as before. The exhaust conduit 148 of the motor 124 has an adjustable-orifice valve 150 to limit its maximum speed, and leads into an exhaust control valve 152 like that of FIGS. 1 and 3, having a movable finger 174 engaging one edge of the sheet 104. Similarly, the exhaust conduit 153 of the motor 132 has an adjustable-orifice valve 156 and an exhaust control valve 154. The

valves

152 and 154 are mounted on arms 52, and their spacing is adjustable to equal various sheet widths by loosening screws 56 which mount the arms on brackets 36. This apparatus operates on substantially the same principles as that of FIGS. 1-4. The speed of each uncurler is individually governed by the location of a corresponding edge of the sheet, and the lateral pull exerted on the sheet by each uncurler is a function of its rotational speed. The edges are independently guided in tracks determined by the locations of the

valves

152 and 154.

The two embodiments thus far described are particularly suitable for handling stretchable goods, in that they hold each edge in a given track independently of the other, and therefore impose width control on the sheet. For handling goods which are not substantially stretchable but have a stable width, it is appropriate to guide only one edge of the sheet. The lateral position of the unguided edge is determined by the width of the goods. The guiders of FIGS. 1 or 5 can be adapted to this mode of operation simply by omitting either one of the edge-sensing means 152 or 154, and regulating the speed of the

corresponding motor

124 or 132 at a substantially constant value by appropriate settings of the pressure-regulating valve 146 and the

corresponding orifice valve

150 or 156. The remaining edge-sensing means 152 or 154 continues to control the speed of its

connected motor

124 or 132 in accordance with the previously-explained principles of operation.

Another construction suitable for guiding nonstretchable sheet or web material is illustrated in FIG. 6. This apparatus employs scroll rolls and 102 like those of FIGS. 1-4, and other parts of a similar nature are also numbered alike.

The shaft 108 and the roll 102 are driven at a substantially uniform speed with respect to that of the sheet 104, by motive means which include a drive shaft 200, a belt 202, and sheaves 204 and 206, the latter being fixed on the shaft 108 adjacent to the sheave 130. The shaft 200 may be driven by any convenient driving component, roll, or motor (not shown) which may be available as a component of the sheet-processing range in which the guiding apparatus is used. The belt drive ratio should be chosen to drive the roll 102 at a linear surface velocity somewhat greater than the velocity of the sheet 104, perhaps 10-20 percent greater. This insures moderate spreading of both edges of the sheet at all times, and allows the speed of the roll 100 to be reduced below that of the roll 102, when necessary for guiding purposes, without being lower than the velocity of the sheet. Wrinkling could result if either of the

rolls

100 or 102 were to be driven slower than the sheet is fed.

The belt 136 and sheave 134 serve to drive the sheave 126 and roll 100 through a variable-speed drive or transmission 208 of a conventional commerciallyavailable type. The speed ratio of the drive 208 is adjustable from values of less than lzl to more than lzl, by angular positioning of a control shaft 210. A reversible servo-motor 212 serves to position the shaft 210 in response to control signals received from a single edgeposition sensing element or valve 154, whose finger 174 follows one edge of the sheet 104.

The control system is so arranged that a displacement of the right-hand edge of the sheet 104 to the left, as viewed in FIG. 6, moves the shaft 210 in a sense to reduce the speed ratio of the drive 208, thereby slowing the roll 100 with respect to the roll 102. This results in a net lateral pull on the sheet 104 toward the right, until it is restored to the proper track. Conversely, a displacement of the sheet to the right in FIG. 6 increases the speed ratio of the drive 208 and drives the roll 100 faster than the roll 102, pulling the sheet toward the left into its proper position.

A fluid pressure control system is shown in FIG. 7 for controlling the speed ratio of the drive 208 in response to the position of the finger 174, in accordance with the foregoing principles. Air pressure is supplied to a conduit 220 through an adjustable pressure-regulating valve 222 and a flow-limiting orifice valve 224. The supply conduit 220 is connected to a passage 168 in a schematically-illustrated control valve 154, which is similar to the valve 152 shown in FIG. 3 except that the passage 168 is connected both to a bleed orifice 170 and to a pressure-signal conduit 226. The extent to which the bleed orifice 170 is opened by the valve element 172 depends upon the position of the sheet edge and the finger 174, with the result that a signal pressure delivered to the conduit 226 is directly proportional to the edge position. A displacement of the sheet edge to the right in FIGS. 6 or 7 tends to close the orifice 170 and increase the signal pressure, while a leftward movement lowers the pressure, both in proportion to the amount of displacement from the normal edge position.

This signal pressure is delivered to a conventional, commercially available pneumatic servo-motor 212A, which angularly positions the shaft 210 in a manner to reduce the speed ratio of the drive 208 in response to a reduction in the signal pressure in the conduit 226, or to increase the speed ratio if the signal pressure rises. A pressure reduction reflects a leftward displacement of the sheet 104, and the consequent decline in the speed of the belt 128 and roll 100 allows the sheet 104 to be drawn to the right by the roll 102. Conversely, a pressure increase, arising from a deviation of the sheet edge toward the right, increases the speed of the belt 128 and the roll 100, and draws the sheet 104 leftward into its proper position. The

valves

222 and 224 should be adjusted so that the signal pressure will produce a 1:1 speed ratio of the

rolls

100 and 102 when the right edge of the sheet is in the desired track.

An alternative electrically-operated control system is shown in FIG. 8, in which parts similar to those of FIG. 7 are similarly numbered. An edge-sensing switch replaces the valve 154. A switch lever or finger 230 is pivotally mounted at 232, and is biased by a compression spring 234 against one edge of the sheet 104. The finger is electrically conductive, and is connected to a voltage source 236. It bears a contact 238, which is engageable with either of two

contacts

240 and 242 when the sheet edge devicates sufficiently far to left or right. The spacing between these contacts defines tolerance limits of edge displacement, between which no control action takes place and the sheet may wander freely. It will be understood that the spacing between the contacts may be chosen to bring about any desired compromise between the amount of lateral edge wandering that is tolerable in a given application, and the frequency of control actuation or hunting that may be considered acceptable.

The

contacts

240 and 242 are electrically connected by

leads

244 and 246, respectively, with a conventional, commercially-available electrical servo-motor 212B. The servo-motor is so arranged and connected that energization of the contact 240 results in a repositioning of the shaft 210 which reduces the speed ratio of the drive 208, and energization of the contact 242 increases the speed ratio. Therefore a leftward motion of the sheet edge to the tolerance limit established by the contact 240 causes a reduction in the speed of the belt 128 and the roll 100, which in turn permits the roll 102 to draw the sheet toward the right as viewed in FIGS. 6 and 8. An excessive deviation of the sheet toward the right closes the contact 242 and increases the speed of the belt 128 and the roll 100, pulling the sheet leftward.

A modification of the apparatus of FIGS. 1 or 5 for use with non-stretachable material includes a driving connection between one of the rolls or 102, or one of the uncurlers 14, and a range-driven shaft like the shaft 200 of FIG. 6, or other motive means whose speed is regulated at a substantially constant value relative to the rate of sheet feeding. The remaining roll or uncurler may be driven by its

connected motor

124 or 132, under the speed control of a single edge-

sensing element

152 or 154; or it may be driven by a fluid or electric variable-speed motor, under speed control by the edge-sensing means 154 of FIG. 7, or the edgesensing means 230-246 of FIG. 8.

An embodiment shown in FIG. 9 utilizes a rangedriven shaft 200 like that shown in FIG. 6, in combination with electricallyoperable normally-engaged

clutches

250 and 252. Parts similar to those of preceding embodiments are similarly numbered. Both of the

rolls

100 and 102 are normally driven at a constant speed, somewhat greater than that of the sheet 104, by the shaft 200 through a drive belt 202, sheaves 204 and 206, and the

clutches

250 and 252. A belt 136 is driven by a sheave 130 connected to the input shaft of the clutch 250, and drives a sheave 134 connected to the input shaft of the clutch 252. The latter clutch drives the roll 102 through the shaft 108, while the clutch 250 drives the roll 100 through a belt 128 trained on sheaves 126 and 122. The

clutches

250 and 252 are normally engaged, but may be independently disengaged by energizing them through

leads

246 or 244, respectively. These leads are connected to an electrical edge sensor 230 like that shown in FIG. 8, and the connections are arranged so that a displacement of the tinger 230 to the left in the drawing energizes the lead 246, while a displacement to the right energizes-the lead 244. A displacement of the sheet 104 to the right in the drawing will thus disengage the clutch 252, mo-

mentarily interrupting the drive of the roll 102, and allowing the roll 100 to draw the sheet toward the left. A deviation of the sheet 104 to the left, on the other hand, disengages the clutch 250, momentarily interrupting the drive of the roll 100 and permitting the roll 102 to draw the sheet back into the proper path.

An alternative control arrangement adapted for controlling the width of stretchable sheet material may employ single electrical contacts each cooperating with a separate edge-sensing finger disposed at either edge of the sheet (not shown). Each contact is connected to one of the

clutches

250 and 252, and the contacts are so arranged that an outward movement of the left edge of the sheet in FIG. 9 temporarily disengages the clutch 250 and the roll 100, while an outward displacement of the right-hand edge temporarily disengages the clutch 252 and the roll 102. The resulting system is sensitive both to lateral bodily displacements of the sheet and to increases in its overall width. A lateral displacement without a change in width energizes only one contact, which disengages the roll toward which the sheet has shifted. An increase in overall width, on the other hand, causes both

rolls

100 and 102 to become disengaged, discontinuing the spreading action of both rolls until such time as the sheet width contracts to the proper value. However, the system would not respond to a decrease in overall width of the sheet, since in that case both

rolls

100 and 102 would continue to rotate at their original speeds. For that reason, this alternative arrangement is feasible only where the rolls are run at a speed sufficiently greater than the sheet, and exert sufficient spreading action, to ensure that the overall width of the sheet will at no time become less than the desired value.

What we claim is:

1. Apparatus for guiding a longitudinally-traveling indefinite length of sheet material, comprising:

a pair of rotatable means having peripheral surface portions constructed and arranged for engaging and stroking the opposite edge portions of the sheet laterally outwardly away from the longitudinal centerline of the sheet;

drive means constructed and arranged for driving said rotatable means with differentiable linear surface velocities, said drive means including means for supplying pressure fluid, variable-speed fluidoperated motive means connected to receive pressure fluid from said supply means and drivingly connected with said rotatable means, and at least one adjustable exhaust valve means connected to control the rate of fluid exhaust from at least a portion of said motive means, thereby to control the relative surface velocities of said rotatable means; and sheet edge-sensing means constructed and arranged for detecting the lateral position of at least one edge of the sheet and operatively connected for adjusting said exhaust valve means to control the relative surface velocities of said rotatable means in response thereto; said edge sensing means maintaining a predetermined ratio between the surface velocities of said rotatable means while the sheet travels in a predetermined path, and being operative to adjust the ratio between the surface velocities of said rotatable means in response to a movement of at least one edge of the sheet away from said predetermined path, said adjustments in i0 velocity ratio being made in a sense to guide the sheet in said predetermined path.

2. Apparatus as recited in claim 1, said drive means being operable normally to drive said rotatable means with a surface velocity in excess of the velocity of travel of the sheet thereby to tend to spread the sheet laterally, and being operable to reduce the velocity of at least one of said rotatable means to a value which remains at least equal to the velocity of the sheet in response to a movement of the edge of the sheet engaged by said one rotatable means laterally outwardly from a predetermined path.

3. Apparatus as recited in claim 1, said fluid-exhaust valve means being formed with an exhaust passage, and including a movable valve element valving said exhaust passage, said edge-sensing means being operable to adjust the area of said exhaust passage in response to a movement of an edge of the sheet laterally from said predetermined path.

4. Apparatus as recited in claim 3, said edge-sensing means being operative to adjust the area of said exhaust passage in proportionate response to displacement of an edge of the sheet from said predetermined path.

5. Apparatus as recited in claim 1, said drive means further including at least one adjustable flow control valve serially connected with said motive means and said exhaust valve means for limiting the rate of fluid exhaust from said motive means, thereby to limit the maximum velocities of said rotatable means in a fullyopen position of said exhaust valve means.

6. Apparatus as recited in claim 1, said motive means including a pair of variable-speed fluid-operated motors each drivingly connected with one of said rotatable means;

a pair of said adjustable exhaust valve means each connected to control independently the rate of exhaust from one of said pair of motors;

said edge-sensing means being constructed and arranged to detect the positions of each edge of the sheet and to adjust said exhaust valve means independently, each in response to the position of a corresponding edge of the sheet, whereby said apparatus guides both edges of the sheet and thereby controls its width.

7. Apparatus as recited in claim 1, said drive means being constructed and arranged to drive one of said rotatable means at a predetermined surface velocity; and said exhaust valve means and motive means being operable to control the surface velocity of the other of said rotatable means at a value less than, equal to, or higher than said predetermined velocity, in response respectively to positions of an edge of the sheet engaged by said other rotatable means laterally outwardly of a predetermined path, in said path, or laterally inwardly of said path.

8. Apparatus as recited in claim 1, said rotatable means comprising a pair of rotary selvage uncurlers one arranged to engage each edge portion of the sheet and comprising rotatable wheel means for stroking the edge portions outwardly away from the longitudinal centerline of the sheet when rotated in a direction such that portions of the wheel means engaging the sheet have components of linear velocity extending in the direction of sheet travel.

Claims

1. Apparatus for guiding a longitudinally-traveling indefinite length of sheet material, comprising: a pair of rotatable means having peripheral surface portions constructed and arranged for engaging and sTroking the opposite edge portions of the sheet laterally outwardly away from the longitudinal centerline of the sheet; drive means constructed and arranged for driving said rotatable means with differentiable linear surface velocities, said drive means including means for supplying pressure fluid, variablespeed fluid-operated motive means connected to receive pressure fluid from said supply means and drivingly connected with said rotatable means, and at least one adjustable exhaust valve means connected to control the rate of fluid exhaust from at least a portion of said motive means, thereby to control the relative surface velocities of said rotatable means; and sheet edge-sensing means constructed and arranged for detecting the lateral position of at least one edge of the sheet and operatively connected for adjusting said exhaust valve means to control the relative surface velocities of said rotatable means in response thereto; said edge sensing means maintaining a predetermined ratio between the surface velocities of said rotatable means while the sheet travels in a predetermined path, and being operative to adjust the ratio between the surface velocities of said rotatable means in response to a movement of at least one edge of the sheet away from said predetermined path, said adjustments in velocity ratio being made in a sense to guide the sheet in said predetermined path.

5. Apparatus as recited in claim 1, said drive means further including at least one adjustable flow control valve serially connected with said motive means and said exhaust valve means for limiting the rate of fluid exhaust from said motive means, thereby to limit the maximum velocities of said rotatable means in a fully-open position of said exhaust valve means.

6. Apparatus as recited in claim 1, said motive means including a pair of variable-speed fluid-operated motors each drivingly connected with one of said rotatable means; a pair of said adjustable exhaust valve means each connected to control independently the rate of exhaust from one of said pair of motors; said edge-sensing means being constructed and arranged to detect the positions of each edge of the sheet and to adjust said exhaust valve means independently, each in response to the position of a corresponding edge of the sheet, whereby said apparatus guides both edges of the sheet and thereby controls its width.