US2781178A

US2781178A - Constant web tension unwinding mechanism

Info

Publication number: US2781178A
Application number: US344520A
Authority: US
Inventors: Jr Richard Leb Bowen
Original assignee: Individual
Current assignee: Individual
Priority date: 1953-03-25
Filing date: 1953-03-25
Publication date: 1957-02-12
Anticipated expiration: 1974-02-12

Description

Feb. 12, 1957 Filed March 25, 1953 R. LE B. BOWEN, JR

CONSTANT WEB TENSION UNWINDING MECHANISM 2 Sheets-Sheet l R Q g \x INVENTOR.

@ B:- Richurd'LeBoron Bowen,Jr.

KN BY & K1 3%3 Mflm \0 N ATTORNEY 1957' R. LE B. BOWEN, JR

CONSTANT WEB TENSION uuwmomc MECHANISM 2 Sheets-Sheet 2 Filed March 25, 1953 JNVENTOR. Richard LeBoron Bowen, Jr.

ATTORN EY CONSTANT WEB TENSION UNWINDING MECHANISM Richard LeB. Bowen, Jr., Pawtucket, R. 3.

Application March 25, 1953, Serial No. 344,520

9 Claims. (Cl. 242-75) This invention relates to a constant web tension unwinding mechanism and more particularly to a mechanism for maintaining a constant speed on the web unwinding mecham'sm through a variable speed transmission responsive to the change in brake speed which reacts to control the pressure on the brake.

One of the objects of the present invention is to provide a constant braking force in a web unwinding mechanism.

Another object of the present invention is to provide a braking force mechanism which inherently will permit the accurate duplication of the braking force.

Other objects of the present invention will be pointed cutin part and become apparent in part in the following specification and claims.

The present application is related in the mental concept of web control as expressed in my co-pending applications Serial No. 313,889, filed October 9, 1952, now Patent No. 2,758,472, dated August 14, 1956, and Serial No. 327,003, filed December 19, 1952.

Uniform or constant tension is a prerequisite to uniformity of product in many web processing machines such as textiles, paper, imitation leather, printing and the like. Especially is this true in coating machinery where the tension on the web effects the nature of the application of the coating being applied to the cloth. Thus, when a supply roll of cloth is placed in a machine the cloth should be drawn ed at a constant speed and at a given tension so that as the diameter of the supply roll decreases the speed or linear travel of the cloth is maintained constant. However, the tension on the cloth increases as the drag on the supply roll increases because the decreasing diameter produces more revolutions per minute. It is necessary, therefore, to decrease the drag or friction on the supply roll shaft if the tension on the cloth is to be maintained constant. Past devices have failed to automatically control the drag and thereby regulate the tension accurately in accordance with the changing tension produced as the supply roll decreases in diameter.

This failure was due in part to the nature of the braking mechanism which consisted of the conventional mechanical arrangement of a brake drum and a shoe provided with a brake lining. The coefiicient of friction between the drum and shoe varied due to the heating caused by the period of operation and the unevenness of the parts and oil, dust accumulation so that the brake slipped and grabbed. There was no way of determining a brake setting for future use. The present invention contemplates an oil pump the pressure of which is always determinable and which will minimize the disadvantages of a brake drum and shoe.

Referring to the drawings in which similar characters of reference indicate coresponding parts in all the figures:

Figure 1 shows an embodiment of the present invention in diagrammatic form, for the sake of clarity and simplicity and presents the mechanism as applied to an unwinding device. 7.

2,781,178 Patented Feb. 12, 19 57 ice Figure 2 is a diagrammatic form of mechanism which is another modification of the mechanism illustrated in Figure 1.

Referring to the drawings and particularly to Figure 1, wherein a strip or web of material 11 is being withdrawn from a beam 12 by means of a drum 16. Beam 12 is secured to an axle 13 which has fixed to it bevel gear 14 which meshes with bevel gear 15 fixed to 'a shaft 20 of a continuously variable speed transmission, generally indicated by reference character 17. A second shaft 21 of variable speed transmission 17 is operatively connected to a gear pump generally indicated by reference character through a shaft 36, sprocket 33 fixed to shaft 36, sprocket 32 fixed to shaft 21 and chain 34 con-' necting sprockets 32, 33. A reservoir 38 is provided and is operatively connected to gear pump 35 through suction line 37 and discharge line 40. A discharge valve 41 inserted in line controls the power exerted by the gear pump 35. A pressure gage 42 inserted in line 40 gives a relative indication of this power.

The variable speed transmission 17 comprises a pair of parallel shafts 20 and 21 rotatably mounted in a housing 22. Each shaft 20, '21 carries a pair of coned disks 23, 24, respectively, forming expansive V pulleys which are splined to said shafts. Coned disks 23, 24 are opera- 7 tively connected through edge-active belt 25 and may be simultaneously and oppositely adjusted to provide variable speed by the simultaneous adjustment of levers 26 and 27 which are operatively connected to coned disk 23, 24 and pivotally separated by lever 28. The ends of levers 26, 27 are fixed to threaded shaft 36 by means of threaded bearings 31, 32. The rotation of threaded shaft 30 simultaneously and oppositely moves disks 23, 24 on shafts 20, 21, thereby varying the speed of rotation-of shaft 20 relative to shaft 21.

Threaded shaft 39 is operatively connected to a reversible electric motor 44 by means of sprocket 47 forming part of a slip clutch 29 mounted on shaft 30, sprocket 46 fixed to motor shaft and chain 48 connecting sprockets 46,47.

The discharge line 40 is in communication with a pressure switch, as for example, a Bourdon tube 52 which controls the operation of motor 44 through a switch 43. Current is supplied to motor 44 through wires and 51. A switch 53 is used for reversing motor 44. It has one single pole normally closed circuit and one single pole normally open circuit. In operation when a roll of material is being unwound the normally closed circuit of switch 53 connects wire 54 with the contact of switch 43. Thus when switch 43 is closed by the action of Web 11, current flows through line 50, and through line 51, switch 43, switch 53, line 54, to motor 44. The reversing action of the switch 53 will be explained later. In this initial arangement of switch 53, wire 55 is open.

In operation, web 11is being withdrawn from beam 12 by drum 16, which is driven at a constant speed by means,

not shown, and thus withdraws Web 11 at a constant" As beam 12 is unwound, its-diameter" decreases and its speed of rotation increases. This increase in speed is transmitted to pump 35 through bevel linear velocity.

gears 14, 15, shaft 20, cones 23, belt 25, cones 24, shaft 21, sprockets 32, 33, chain 34 and shaft 36.

As soon as the pump receives the increase in'speed, the

-17, and thus is a'modification of Figure 1.

web.

When the beam 12 is completely unwound, the variable speed transmission 17 has shifted to one limit in that threaded bearings 31, 32 on threadedlshaft, 30 are'atjthe approximate minimum distance from each other. For a fresh beam the transmission should. be. at" the opposite limit with the bearings 32., 32at the approximate maximum distance from eachcther. To eifect'this, hand wheel 56 fixed to shaft 21 is turned and reversing switch 53 is manually actuated, breaking contact in wire 54 and making contact 'in wire 55, thereby running the motor in the opposite direction frorn'that stated above and setting-the transmission at the. opposite limit. After the transmission has been reset,'the new beam may be put in. It is necessary to-turn thehandwheel -56 to reset the transmission, since the relative distances of the coned disks cannot be changed unless the belt 25. is in motion.

threaded shaftfiii remains stationary. The torque applied to shaft 39 by slip clutch 29 makes one pair of disks, either 23 or 24, grip the belt 25 tightly. Only if belt 25 is moving can the relative positions, of the two pairs of disks, 23,24 be changed.

Figure 2 diagrammatically depicts'a modified form of mechanism for controlling the variable speed transmission Here there is a governor generally indicated by 1 20 which controls the current to an electric motor '44 which changes the speed of the transmission.

Governor 120 consists of a rotatable shaft 121 to which is fixed connector 122 and on which is slidably mounted fiange123. Arms 124 are pivotally mounted to connector 122, and links125 connectarms 124 with flange 123. When flange 123 rises, a circuit is completed from Wire 51 to wire 54 through contact 126, wire 51 being connected to the metallic governor as at 127. Shaft 121 is operatively connected to shaft 36 of pump 35 by means of sprockets 13%, 131, and chain 132. a

. As previously described, when beam 12 unwinds, shafts 20, 21, shaft 35 and pump 35 tend to increase in speed; Since shaft 121 of governor 120 is operatively connected to shaft 36, the governor will also increase its speed of rotation. As .the speed increases, arms 124 are thrown outward by centrifugal force, and flange 123 rises to complete a circuit through contact 126. This closes the electrical circuit and current is supplied to motor-44 through wires 50 and 51. To reset the mechanism after a beam has been unwound, reversing switch 53 and hand wheel 56 are used as described for Figure l.

Motor 44 could; be controlled by other electrical switches responsive to changes in speed, such as a centrifugal switcher the speed responsive switch shown by the Butterworth et al. Patent N0. 2,392,226;

In the mechanisms described above, the braking mecha nism hasconsisted'or a. gear pump, whose braking force is determined-by the amount of press maintained in the discharge line.

. this gear pump could be replaced byct'her mechanical it will. of course be understood that equivalents. a

fl-Having shown anddescribed preferred embodiments of the present invention, by way of examplerit should be the usual first shaft, second shaft, andspeed changing,

mechanism, said-first shaft being arranged for engage. ment'with sa d beam,'a gear pump, said second shaftbeing arranged for direct engagement with saidgear pump, a

' reversible electric; motor including an electrical circuit thereto, said speed changing mechanism being arranged for engagement with said reversible electric motor, and means for controlling said electrical circuit by said gear pump.

2. in a constant web tension unwinding mechanism, a beam carrying the web, said web travelling at a constant linear speed, a variable speed transmission comprising the usual first shaft, second shaft and speed controlling shaft,

' reversible electric motor comprising an electric 'circuit,. 7

said first shaft being arranged for engagement withsaid beam, a gear pump comprising a reservoir, a discharge 7 line and a suction line, a throttling valve located in said discharge line, a Bourdon tube connected to said discharge line, said second shaft being arranged for direct drive engagement with said" gear pump, 'a. reversible electric motor including an electrical circuit thereto, said speed controlling shaft having a slip clutch which is arranged for engagement with said reversible electric motor, a.

switch, in said electrical circuit for controlling the direction of rotation of said reversible electric motor and 'a trolling said electrical circuit. I

3. in aconstant web tension unwinding mechanism, a beam carrying the web, the web travelling at aconstant control switch forming part of said Bourdon tube for con linear velocity, a variable speed transmission comprising the two usual power transmitting shafts and speed changing mechanism, a driving connection between one of said shafts and said beam, a gear pump, comprising a reservoir, a discharge line and 'a suction line, a throttling valve locatedin'said discharge line, a pressure responsive electrical switch in the'discharge line, a direct driving connection between the second of said shafts and said gear pump, a reversible electric motor, a source of electric current, said electric motor being arranged. for engagement with said speed changing mechanism, said pressure responsive switch in circuit with said source and said motor. I

4. In a constant web tension unwindingmechanism, a

cam carrying the web, the web travelling at a constant linear velocity, avariable speed transmission comprising the two usual power transmittingshafts and speed changing mechanism, a driving connection between one' of said shafts and said beam, a gear pump comprising a reservoir, 7

a discharge line and a suction line, a throttling valve lo cated in said discharge line, a pressure responsive electric switch in the discharge line, a direct driving connection between the second of said shafts and said gear pump, a

reversible electric motor, a source of electric current, said electric motor being arranged for engagement with said speed changing mechanism, said pressure responsive switch in circuit with said source and saidmotor.

5. in a constant web tension unwinding mechanism, a beam carrying the web, said web travelling at a constant linear speed, a variable speed transmission provided with 'a first shaft, a second shaft, and speed changing mechanism, said first shaft being arranged for engagement with said beam, a gear pump-, said second shaft being arranged for direct engagement with said gear pump, a

said speed changing mechanism being arranged for engagement with said reversible'electric motor, and means responsiveto thespeed of rotation of said gear pump for controlling said electric circuit. 1

6. in a constant web tension unwindingmech-anism, a beam carrying'a web, said web travelling at a constant linear speed, a variable speed transmission provided with i a first shaft, a second shaft and speed changing mechanism, I

said first shaft being arranged for engagement with said earn, a gear pump, said second shaft being arranged for direct engagement with said gear pump, a reversible elec-- tric motor including an electric circuit thereto, said speed changing mechanism being arranged for engagement with Y said-reversible electric-motor, and means'forr-controlling said electriccircuit by said gear pump, said means including a normally open electric switch in said electric circuit. a I V 7.1m a constant web tension unwinding mechanism according to claim 6 wherein the engagement arrangement between said speed changing mechanism and said electric motor includes a slip clutch.

8. In a constant Web tension unwinding mechanism according to claim 6 wherein a pressure gauge and a throttling valve are positioned in the discharge line of said pump.

9. In a constant web tension unwinding mechanism according to claim 6 wherein a governor is connected to said gear pump and operates to close the said normally open electric switch.

References Cited in the file of this patent UNITED STATES PATENTS