US2462558A

US2462558A - Tension control means for running webs

Info

Publication number: US2462558A
Application number: US540444A
Authority: US
Inventors: Joseph S Scheuermann; Thomas N Carter
Original assignee: Cameron Machine Co
Current assignee: Cameron Machine Co
Priority date: 1944-06-15
Filing date: 1944-06-15
Publication date: 1949-02-22
Anticipated expiration: 1966-02-22

Description

22, 1949. J; s. SCHEUERMANN ET AL 5 TENSION CONTROL MEANS. FOR RUNNING WEB Filed June 15, 1944 4 Sheets-Shoat 1 INVEN TORS .1 Wm

Feb. 22, 1949. J. 5. SCHEUERMANN ETAL 2,462,555

TENSION CONTROL MEANS FOR RUNNING WEB vFiled Juns 15, 1944 4 Shoots-Sheet 2 h 1949- J. s. SCHEYUERMANN ETAL 2,452,558

TENSION CONTROL MEANS FOR RUNNING WEB Filed June is, 1944 4 Sheets-Sheet s IHIIIIIHM...

INVENTORS' Jase 4k J. Malawian/z By Hands/W (hr/(r Feb. 22, 1949.

J. S. SCHEUERMANN ET AL TENSION QON'I'ROL MEANS FOR RUNNING WEB 4 Sheets-Sheet 4 Filed June '15. 1944 INVENTORS xplziJz/wurrmann INTO/WE Y 7710mm AZ far/er Patented Feb; 22, 1949 TnNsroN coN'rnoL MEANS FOR RUNNING wens Joseph S. Scheuermann and Thomas N. Carter, Chicago, Ill., asslgnors to Cameron Machine Company, Brooklyn, N. Y., a corporation or New York Application June 15, 1944, Serial No. 540,444

4 Claims.

The present invention relates primarily to machines employing tension control for a, tensioned running web of flexible material such as paper, and has for its main object and feature 'theprovision of means for more accurately and quickly controlling the tension of the web than has heretofore been possible under the varying conditions that arise during the operation of the machine. In the accompanying drawings the invention is disclosed in several concrete and preferred forms in which:-

Fig. 1 is a somewhat diagrammatic view in side elevation showing the invention applied to two types of machines, one, an unwinding mechanism for a web of flexible material and, another, a winding machine for said web;

,Fig. 2 is a horizontal sectional view substantially on the planes of irregular line 2-2 of Fig. '1, showing part of the unwinding mechanism;

Fig. 3 is a horizontal sectional view substantially on the plane of line 3-3 of Fig. 1, showing part of the winding machine;

Fig. 4 is a sectional view of one type of fluidactuated operating devicejsuch as may be used either in connection with the brake rod of the brake of the unwinding me'chanisnror with the "clutch rodof the slip-friction drive of the winding machine; and

Figs. 5, 6 and 7 are vertical sectional views through a valve-mechanism that may be used in connection with either or other forms of the invention. Fig. 5 shows the position of the parts when they are in equilibrium; Fig. 6 shows the position of the parts when the intake valve is open and the outlet valve is closed; and 'Fig. '7 shows the position of the parts when the outlet valve is open and the inlet valve is closed.

A'indicates an unwinding mechanism such as a mill roll stand, and Bis a, winding machine. C is a processing machlnesuch as a printing press which acts on web W in its passage from A to B. It will be understood that it is not necessary to have a battery of machines such as A, B and C in order to practice the invention; the arrangement shown is merely a. convenient, way of exemplifying that the invention can be embodied in different machines.

Web W, in unwinding from a roll of wound material or mill roll MR. in machine A, passes over two guide rollers l and II, and intermediate tension-control roll I2, which latter engages a blght or loop in the web formed between rollers l0 and -II. Tension-control roll I2 is mounted on .a reciprocatory carriage l3. It indicates a power device that exerts a force on carriage l3 in opposition to that exerted by the web on roll l2. Power device I4 is here a weight suspended on the free end of flexible connection I'B, passing over sheave H, the other end 02 con- 5 nection l6 being secured to bell-crank l8, pivoted at IS on the framework, said bell-crank being connected by means of link 20 to reciprocatory carriage l3. Web W, in passing to winding machine B, travels over a series of instrumentalities similar to those just described in connection with machine A, and it will be suflicient to say that such elements in machine B as correspond with those of machine A are given the same reference char acters with an added exponent.

In machine A, supporting shaft 2|, carrying mill roll MR, is controlled by a variable brake 22', the braking effect of which, in accordance with well-understood practice, is controlled by the movement of reciprocatory carriage [3. In

machine B, winding shaft 23, on which web W is wound, is driven by a variable slip-friction drive or clutch 24, the force exerted by the clutch being, i in accordance with well-understood practice, controlled by the movement of reciprocatory carriage 26 I3 The object of these arrangements is to obtain, as near as possible, constant tension on the web. For a full description of the general construction and function of the tension-control devices above referred to, U. S. Patent No. 2,331,765

30 can be consulted.

Webs traveling from or to machines of the type indicated at A or B, 'move at a prodigious rate of speed, and it is therefore, highly desirable, in order to'malntain high speeds, that variations in tension of the web from the desired one, shall be accurately and quickly corrected. This is true whether the web tension becomes excessive or whether slack develops in the bight engagedby tension-control roll I 2 or I2 In the one instance,

40 the web may'snap and, in the other, the slack may continue to develop so fast that the machine may lose control of the web. The connections heretofore used to transmit the movement of carriage [3 or I3 to variable-speed control devices, such as variable brake 22 or variable clutch 24, have generally been mechanical elements, and it has been found that an undesirable time-lag ocours in overcoming the inertia of such mechanical elements, thereby tending .to prevent a prompt correction of a variation in web tension. It is therefore proposed to eliminate, as much as possible, mechanical connections and to utilize fluidpressure, preferably in gaseous form, in'controlling the brake or the clutch. 25, or 25 indicates a fluid-actuated operating device, which can be moved up or down in be of any suitable construction, but which is here in the form of a casing 26 divided by a flexible diaphragm 21. Connected to said casing at one side of the diaphragm is a

duct

28 or 28 leading from a source of supply of fluidpressure (not shown). Connected to said diaphragm is a slidable member 28 pivotally connected to a-pivoted lever 80 that engages, in the case of machine A, a brake-control rod 3I or, in the case of machine B, a clutch-control rod 3I Interposed in

duct

28 or 28 is a valve-

mechanism

32 or 32 which valve-mechanism (Figs. 5, 6 and '7) is here constructed as follows: The valve casing is divided into a high-pressure chamber 83, connected to the source of supply, and a lowpressure chamber 34, connected to fluid-actuated

operating device

25 or 25 as the case may be. 35 is an inlet valveto open or close port 35 between the high and low-pressure chambers, said inlet valve being urged into its closed position by spring 31. 38 is an outlet valve to open or close port or exhaust 39. Valves 35 and 38- are connected by means-of a valve stem" so as to move in unison. M is a movable valve seat, having port 39, associated with said outlet valve 38. 42 and 43' are two controllers, for said valve-mechanism, acting in opposition to each other. One of these, 42, moves in response to movements of carriage I3 or I3 The other, 43, is a flexible dia ragm, the edges of which are anchored in the casing as shown, which engages movable valve seat 4I within low-pressure chamber 34 of the valvemechanism and is thus responsive to fluid-pressure in fluid-actuated

operating device

25 or 25, as the case may be. Controller 42 consists here of a plunger 44 movable in guide 45 and bearin against spring seat 46, between which latter and movable valve seat 4i, 9. spring 41 is interposed. The means for operating controller 42 from reciprocatory carriage I3 or I3 as the case may be, consists of a cam lever 43 on the framework. The free end of cam lever 48 or 48 rests with its came face on tension-control roll I2 or I2 or other member of carriage I3 or I3 so that movements of said carriage will lift or lower-the cam lever. Plunger .44 of controller 42 engages the upper surface of the cam leverand it will conformity with the movements of said cam lever, whereby the tension of spring 41 will be varied.

As explained in Patent No. 2,331,765, previously referred to, carriage I3 of machine A has, during the unwinding operation, a progressive movement of traverse in slot I3II from a position adjacent one end of said slot to a position near the other end thereof, 1. e. from left to right-in Fig. 1. This progressive movement of traverse compensates for the progressive decrease in load MR on supporting shaft or mill roll spindle 2|. Or, to put it differently, the progressive decrease in diameter of the wound material constituting web roll or mill roll MR will produce a progressive change in the tension of the web which is compensated for by the progressive traverse of carriage I3 in slot I3II. It is not intended by the foregoing tougive the impression that the traverse movement of ca age I3 is uninterruptedly in one direction; the tension in reason of decreases or increases in tension due to causes other than decrease in diameter of web roll MR, and therefore-carriage I3 may reciprocate or move back and forth to increase or decrease the brake pressure. Nonetheless, during the unwinding operation, carriage I3 will probe apparent that said plunger will 48 or 48 pivoted at 49 or low-pressure chamber gressively traverse slot I30. When carriage I3 is in the position. shown in Fig. 1, the pressure exerted by the brake is at its greatest, and the movement of carriage I3 from left to right in Fig. 1 will lower plunger 44 and relax spring 41, thereby decreasing the brake pressure; the opposite movement will have the contrary effect. In thecase of machine B, the wound material on winding shaft 23 progressively increases as the winding operation proceeds and this is compensated for by progressive traverse movement of carriage I3 in slot I30 also from left to right in Fig. 1, and reciprocatory movements of carriage I3 will compensate for fluctuations in tension of the web. When carriage I3 is in the position shown in Fig. 1, the pressure exerted by clutch 24 is at its lowest. The movement of carriage I3 from left to right in Fig. 1 will raise plunger 44' and increase tension of spring 41, thereby increasing the pressure of clutch 24; the opposite movement willhave the contrary effect. In comparing the difference in action of machines A and B, it will be noted that, in machine A, carriage I3 moves from a point near pivot 49 of cam lever 48 and that, in so doing, the size of the bight extending between rolls I0 and II is decreased, or the length of the paper path between said rolls is shortened; in machine B, on the contrary, carriage I3 moves from a point furthest away from pivot 49' of cam lever 48', and consequently the size of the bight extending between rolls Ill and II' is increased or the length of the paper path between said rolls is increased. In both instances, the force exerted by weights I5 or I5 remains constant regardless of the position of carriage I3 or I3.

When the fluid-pressure in fluid-actuated

operating device

25 or 25 is such as to operate the variable speed-control device (brake 22 or clutch 24) to give the required constant web tension in any position of carriage I3 or I3, the force exerted by spring 41 of controller 42 against valve seat 4I, and the fluid-pressure exerted against diaphragm controller 43 plus the force of spring 31 on inlet valve 35 will be equalized. The parts of the valve-mechanism will therefore be in'the position shown in Fig. 5, and inlet valve 35 and outlet valve 38 will both be in closed position. If the force exerted by the fluid-pressure in

fluidactuated operating device

25 or 25 is insufficient to properly actuate brake 22 or clutch 24 to maintain the constant tension on the web, then the movement of carriage I3 or I3 will, through the connections described, actuate plunger 44 of controller 42 to increase tension of spring 41 to overcome the force exerted by diaphragm contrailer 43 and spring 31. This will cause valve seat M to be lifted (Fig. 6), carrying with it both outlet valve 38 and inlet valve 35. It will be observed, however, that outlet valve 38 remains in its closed position, although inlet valve 35 is moved to its open position. Fluid under pressure will therefore flow from high-pressure chamber 33 to 34 and thence to fluidactuated operating

device

25 or 25 until equilibrium is restored and the parts reassume the position shown in Fig. 5. On the other hand, if the fluid-pressure in fluid-actuated" operating

device

25 or 25 is in excess of that required to properly actuate brake 22 or clutch 24 to maintain the constant tension on the web, then the fluid-pressure acting on diaphragm controller 43 will overcome the action of spring 41 and will move valve seat 4| away from outlet valve 38 and port or exhaust 38 will be open while inlet port 38 remains closed (Fig. '7) The result is that fluid-pressure from a4eaccs fluid-actuated

operating device

25 or 25 will drain back into low-pressure chamber 34 and out through exhaust 39 until pressure has been reduced to enable spring 41 to close port 39 by moving valve seat 4| against outlet valve 38, where 5 upon the parts will reassume the position shown in Fig. 5.

As previously explained in the foregoing, it will be understood that, at the beginning of the unwinding operation of machine A, the load is greatest and that, as the flexible material or web unwinds, the load becomes less and less. In accordance with well-understood practice, brake 22 should therefore at first exert a powerful braking efiect which becomes less and less as the unwinding of the web proceeds. In the case of machine B, the force exerted by clutch 24 is least at the beginning of the windingoperation and increases as the wound material accumulates on the winding shaft. In both instances, the traverse of carriage l3 or 13 as the case may be, will, in the manner and in association with the means previously described, maintain constant tension on the web.

As pointed out above, the avoidance of time- 5 lag is an important consideration in correcting variations in tension of the web. It has been found that provision can be made in the valvemechanism to give itwhat might be called a hair trigger action. This is accomplished (Fig. 5) by providing a small leak 50 from high-pressure chamber 33 to low-pressure chamber 34, the efiect of which is to constantly tendto activate the valve-mechanism without substantially affecting fluid-actuated operating device 25 or 25'. This 35 tends to overcome any initial reluctance of the. valve elements to move and thus tends to prevent or minimize timelag, and this is accomplished while maintaining the fluid-pressure in 25 or 25' substantially unafiected. Or, to state the matter. more in detail: leak 50 constitutesa by-pass in the valve-mechanism casing, around inlet valve 35, that afiordsa slight continuous flow of fluidpressure notwithstanding changes in position of the valve elements in response to the action of controllers 42 and 43. Assuming the parts of the valve-mechanism to be in the position shown in Figure 5, the slight leak through by-pass will eventually (in the absence of other factors such as variatlonsin web tension) build up a.slight 50 pressure above that required in low-pressure chamber 34 and in 25 or 25. This will act on controller 43 to open to a very slight extent port 39, so that there will be a passage of fluid-pressure from high-pressure chamber 33 to exhaust port 39. the exhaust through 39 balancing the leak through 5D and thereby maintaining the fluid-pressure in fluid-actuated device 25 or 25' substantially unaffected- This has been found to render,the valve elements more sensitive than would otherwise be the case. in that port 39 tends to remain slightly open, and the valve elements adjacent said port will therefore not tend to be too firmly engaged. Good results have been obtained with a leak having a diameter of .00175 of an inch. It is, of course, not intended to limit the leak to this particular size, as different machines or operating conditions might require different treatment; To provide for this, there is shown in 'Fi G an adjustable needle valve 5| device and to the action of the first-mentioned controlling leak 50. In some cases, a similar result can be obtained by providing a leak 52 (Fig. 7) from low-pressure chamber 34 to atmosphere, and this leak likewise can be controlled by an adjustable'needle valve 53.

- Weclaim:

1. In a machine employing tension control 01" movement of traverse, as well as by reciprocations, of a reciprocatory carriage having a roll that engages a bight in said running web, and

, in which both the movement of traverse and the riage in opposition to that exerted by the web on .said roll, means to vary the effectiveness of said speed-control device in response to a progressive change, as well as to fluctuations, in tension of the web including: a fluid-actuated operating device connected to control the speed-control device, a duct leading from a source of supply of fluid under pressure to said fluid-actuated operating device, valve-mechanism interposed in said duct to control the passage of fluid from the source of supply to the fluid-actuated operating device or from the fluid-actuated operating device to an exhaust, two controllers for said valvem'echanism acting in opposition to each other, and means to operateone of said controllers in response to movements of said carriage and to the action of the other controller to admit or cut ofi fluid-pressure from said source of supply to said fluid-actuated operating device, the other of said'controllers being responsive to fluid-pressure in said fluid-actuated operating device and to the action of the first-mentioned controller to open or close said exhaust.

2. In a winding machine for a running web reciprocations, of a reciprocatory carriage having a roll that engages a bight in said running web, and'in which both the movement of traverse and the reciprocations of the carriage are controlled by said web under tension acting on said roll and by a power device for exerting a force on the carriage in opposition to that exerted by the web on said roll, means to vary the effectiveness of said slip-friction drive in response to a progressive change, as well as to fluctuations, in tension of the web including: a fluid-actuated operating device connected to control the slipfriction drive, a duct leading from a source of supply of fluid under pressure to said fluid-actuated operating device, valve-mechanism interposed in said duct to control the passage of fluid from the source of supply to the fluid-actuated operating device or from the fluid-actuated operating device to an exhaust, two controllers for said valve-mechanism acting in' opposition to each other, and means tooperate one of said controllers in response to movements of said carriage and to the action of the other controller to admit or cut off fluid-pressure from said source t of supply to said fluid-actuated operating device, the other of said controllers being responsive to fluid-pressure in said fluid-actuated operating controller to open or close said exhaust.

3. In unwinding mechanism for a web of flexible material in which the shaft that supports the unwinding tensioned web is controlled by a varimoans able brake the load on which is progressively decreased, and -in which the eflectiveness of said brake is varied by a movement of traverse, aswell trolled by said web under tension acting on said roll and by a power device for exerting a force on the carriage in opposition to that exerted by the web on said roll, means to vary the effectiveness of said brake in response to a progressive change, aswell as to fluctuations, in tension of the web including: a fluid-actuated operating device connected to control the brake, a duct leading from a source of supply of fluid under pressure to said fluid-actuated operating device, valve-mechanism interposed in said duct to control the passage of fluid from the source of supply to the fluid-actuated operating device or from the fluid-actuated operating device to an exhaust, two controllers for said valve-mechanism acting in opposition to each other, and means to operate one of said controllers in response to movements of said carriage and to the action of the other controller to admit or cut of! fluid-pressure from said source of supply to said fluid-actuated operating device, the other of said controllers being responsive to fluid-pressure in said fluid-actuated operating device and to the action of the first-mentioned controller to open or close said exhaust.

4. In a machine employing a fluid-actuated operating device, and having a duct leading from a source or supply of fluid under pressure to said fluid-actuated operating device; valve-mechanism interposed in said duct to admitthe passage of actuating fluid from said source of supply to said fluid-actuated operating device, or from said fluid-actuated operating device to an exhaust, said valve-mechanism including: a casing, inlet and outlet valve elements, and two controllers, for said valve elements, acting in opposition to each other, one of which controllers is responsive to fluid-pressure in the fluid-actuated operating device. and said casing having a by-pass around one of said valve elements aflording a slight continuous flow oi fluid-pressure notwithstandin changes in position of thevalve elements in response to the action of the controllers.

JOSEPH S. SCHEUERMANN. THOMAS N. CARTER.

REFERENCES crr n The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name mtg 894,018 Krichbaum July 31, 1908 954,089 Goss Apr. 15, 1910 1,885,851 McKee Nov. 1, 1932 2,014,541 Wappat Sept. 17, 1935 2,259,809 Freeman Oct. 21, 1941 2,304,784 Donaldson Dec. 15, 1942 2,331,765 Carter Oct. 12, 1943 2,343,181 Heinz Feb. 29, 1944