US2765165A

US2765165A - Web tension control means

Info

Publication number: US2765165A
Application number: US296813A
Authority: US
Inventors: Thomas H Johnson
Original assignee: Harris Seybold Co
Current assignee: Harris Corp
Priority date: 1952-07-02
Filing date: 1952-07-02
Publication date: 1956-10-02
Anticipated expiration: 1973-10-02

Description

Oct. 2, 1956 T. H. JOHNSON 2,765,165

WEB TENSION CONTROL-.MEANS Filed July 2, 1952 4 Sheets-Sheet 1 INVEN TOR. 77mm Mbmvsm/ Arrow/5 m Oct. 2, 1956 T. H. JOHNSON WEB TENSION CONTROL MEANS Filed July 2, 1952 4 Sheets-Sheet 2 INVENTOR. man ms H Jofi/wow 4 Sheets-Sheet 3 T. H. JOHNSON I I ll um ll :H

WEB TENSION CONTROL MEANS Get. 2, 1956 Filed July 2, 1952 Oct. 2, 1956 Filed July 2. 1952 TliJOHNSON WEB TENSION CONTROL MEANS 4 Sheets-Sheet 4 IAWOQY c A 1 416 AL 65- 455 fi 17 INVENTOR.

62 OR 96 77-IOMA8 H lam/so United States Patent '0 2,765,165; WEB TENSION CONTROL MEANS Thomas H. Johnson, Hudson, Ohio, assignor to Harris- Seybold Company, Cleveland, Ohio, a corporation of Delaware Application July 2, 1952, Serial No. 296,813

10 Claims. 01. 271-23 This invention relates to web tension control means, that is to say means for controlling the tension of a paper or other flexible web traveling through a printing press or other web handling machine.

It is important to maintain approximately constant tension in the web traveling through the different portions of a printing press for example, and also to maintain equal tension in the various portions of the web in the path which it travels through the machine. Attempts heretofore to accomplish this result have employed manually operated means for adjusting rollers or other web engaging devices designed and positioned to exert pressure on the web. Such a means requires considerable time on the part of the operator, there is a lag in the application of the adjustment after the tension rises above or falls below the optimum, and it may necessitate stopping the press.

One of the objects of the invention therefore is the provision of automatically functioning means for controlling web tension.

Another object is the provision of tension control means comprising a pull roll or the like, the diameter of which may be expanded by the application of heat or contracted by the withdrawal of heat.

Another object is the provision of means for varying the temperature of such a roll comprising means for circulating fiuid through the roll and increasing or decreasing tlie temperature of the circulating fluid.

A further object is the provision of electrical means for controlling the temperature of the pull roll responsive to the operation of a tensiorneter disposed in contact with the moving web.

Other objects and features of novelty will appear as I proceed with the description of those embodiments of the invention which, for the purposes of the present application, I have illustrated in the accompanying drawings, in which Fig. 1 is an elevational view, partly in vertical section, of a pull roll and means for heating and circulating liquid therethrough in accordance with the invention.

Fig. 2 is a fragmental plan view illustrating a tank in which the "liquid is heated and a pump for circulating the liquid.

Fig. 3 is a view similar to Fig. 1, showing a modification.

Fig. 4 is a diagrammatic view showing in elevation a four color printing press equipped with my web tension control means.

Pig. 5 is a perspective view of a tensiometer which may be employed in connection with the invention.

Fig. 6 is a wiring diagram, and

Pig. 7 is a diagrammatic view of a different form of control means.

Referring first to Fig. 4, there is here shown at 10 a roll of paper from which a web 11 is drawn through sets of web directional rollers 12 and 13 and around 'a portion of the periphery of a pull roll 14, thence under a tensiometer 15, later to be described, and into a printing 2,765,165 Patented Oct. 2,1956

. press. Iii this instance the printing press is shown as embodying two impression cylinders 16 and 17, cylinder 16 cooperating with a first blanketand plate cylinder unit 18, 19 and a fourth unit comprising blanket and

plate cylinders

20 and 21. The second impression cylinder 17 receives the web from the lower side of cylinder 16, causes it to be printed by a second unit of blanket and

plate cylinders

22, 23 and by a third unit of blanket and

plate cylinders

24 and 25, after which it is directed back over impression cylinder 16 and thence under a second tensiometer 15', partially around a pull roll 26 and out to a s-heeter or folder not shown. Cooperating with each of the

pull rolls

14 and 26 is a traction roller 27 which is urged by suitable means into position to insure traction over the pull roll.

The present invention has to do with the

pull rolls

14 and 26, which may be identical, and with the equipment employed for regulating the temperature of those rolls and their consequent diameters. When in the length of web a between the pull roll 14 which may be said to be a pushing roll, and the printing press the tension falls below a predetermined optimum, the temperature of the pull roll 14 is lowered to decrease its diameter and its consequent rate of feed and hence increase the tension, while if the tension of the said length of web rises above the desired optimum the temperature of the pull roll 14 is increased so as to feed Web faster and relieve the tension.

In the case of the length b of the web, which is subject to the pull of roll '26, an opposite condition prevails, that is when the tension decreases, the diameter of roll 26 should be increased in order to speed up slightly the travel of this portion of the web. Accordingly, under this condition the invention calls for raising the temperature of the roll to increase its diameter. When the tension of the portion b of the web becomes too high the temperature of the roll 26 should be decreased to slow down the web feed, and this is accomplished by lowering the temperature of the roll.

In Fig. 1 side frame members of a printing press or other web handling machine are indicated at 30 and 31. Brackets 32 and 33 mounted on the frame members support the pull roll. This roll may comprise a fixed cylinder 34 at one end of which is a head 35 carrying a trunnion 36 that is mounted in bracket 32. In the other end of the cylinder there is a head 37 in the center of which is mounted a sleeve 38 which is fixed in bracket 33.

Surrounding cylinder 34 there is a cylindrical shell 40 which constitutes the visible part of the

pull roll

14 or 26 as the case may be. One end of shell 40 is closed by a plug 41 which is adapted to rotate upon trunnion 36, a ballbearing 42 being interposed between them. A liquid seal 43 is also interposed between the trunnion and the plug 41. At the opposite end of the roll the shell carries a hollow plug 44 which is integral with a gear 45 that meshes with a driving gear 46 which turns in synchronism with other parts of the press. Between the fixed sleeve 38 of the rotating plug and gear 44, 45, there is a ba'llbearing 47 and a liquid seal 48 similar to the bearing 42 and seal 43 at the opposite end of the roll.

The shell 40 may be made of metal or other material having a relatively high heat coefficient and possessing 'suflicient strength to carry the load imposed upon it.

Its length must be somewhat more than the width of web to be handled.

Cylinder 34 is spaced from shell 40 a distance sufiicient to provide an annular passage '50 for heated fluid. While a gaseous fluid may be employed i prefer to employ liquid. A light grade of oil is satisfactory for the purpose.

Outside the frame member 31 I provide a mounting plate 51 on which is supported a tank 52 to which a pair of

conductors

53, 54 are connected. Near its lower end the tank has an intake conductor which receives liquid from the discharge side of a gear pump 56, also mounted on plate 51. A conductor 57 is attached to the intake side of the pump;

Conductors

513, 54 and 57 Pass through sleeve 38 into the cylinder 34 and extend through fluid-tight connections in the cylinder so as to communicate with the annular space 50. Obviously, therefore, when the pump 56 is operating liquid will be taken from the space 50 by thepump and circulated through the tank 52 and back through

conductors

53 and 54 to space 50.

Plate 51 may carry a bracket 58 on which is supported an electric motor 59' which operates through a reducing gear'60 to turn the drive shaft 61"of the pump. Suitable means is provided for heating the fluid in tank 52, the means illustrated'cornprisingan electric heating elementsuch asan immersion calrod 62. A thermometer 63 may be installed in order that the operator may inform himself from time to time as to whether the heating and circulating systems are functioning properly. Current for the electric heating element is s upplied by an electric cable that extends from a saturable reactor indicated at 65, the output of which is regulated by an electric control system presently to be described.

In the modification illustrated in Fig. 3 of the drawing the pull roll comprises a shell 68 and an inner cylinder 69 spaced therefrom, these parts being in fixed relation to each other and to annular hubs 70 and 71. Thus no part of the pull roll is stationary as in the first described form. The annular space 72 between the shell 68 and the inner cylinder 69 is connected with the center space 73; of hub 70 and the similar space 74 of hub 71 by

drilled passages

75 and 76 respectively. Cylinder 69 has identical end plates 77 carrying identical bosses 78 which fit tightly within the annular hubs 70 and 71 to close off the spaces 73 and 74 7 These spaces are closed off at their outer ends by bosses 79 and 80 on the inner extremities of aligned shafts 8 1 and 82 which are rotatably mounted in the

frame members

30 and 31 respectively. These shafts have. flanges 83 and 8 which are secured to hubs 70 and 71 by studs 85; The rotating parts, including the aligned shafts 81 and 82 andthe pullroll. are drivenby a gear 86, which is keyed to. shaft 82. Axial passages 87 and 88, are formed in shafts 81 and 82 respectively, and thesepassages communicate. with fittings 89 and 90 which extend into and have rotating connection with fixed

hollow boxes

91 and 92.

93 is a tank provided with baffies 9,4. and 95 to direct'the flow of liquid therethrough. Within the tank there is an. immersion type-electric heating element 96 of U form similar to the calrod '62 and. provided with like electric connections. A tubular conductor 97 is arranged to take liquid from the box 92 and carry it over to a pump 98 on the shaft of which there is a pinion 99 which meshes with a gear 100 pinned. to shaft 81. i The pump draws liquid from conductor 97 and delivers it through a conductor 101 to tank'93. A conductor 102 connected'with the outlet ofthe tank delivers liquid to box 91 from which it flows through passage 87 to space 73, through drilled passage 75 to annular space 72 and through drilled passage 76 and space 74 to passage 88 and back to box 92. Pump 98 therefore is adapted to maintain circulationthrough the pull roll and the tank, and since the temperature of the circulated liquid responds to the intermittent energization of the heating element 96, the diameter of the pull roll is varied to suit web tension conditions.

A tensiometer of well-known commercial form is illustrated in Fig. 5. It comprises a box 105 in which is mounted an electromagnet having a core with three

legs

106, 107 and 108 and an armature 109-pivotally mounted on aspring'110attached to. the armaturenear themiddle median position.

thereof. In an external recess at one end of the bottom of'the box there is a small roller 111 rotatably mounted in a bracket 112 which is attached to the free end of a leaf spring 113 that is secured to the box at the opposite end thereof. The mounting for this roller is so adjusted that the roller bears lightly on the web 11 running beneath it and normally forms a small dimple in the traveling web. Between the bracket 112 and one end of armature 109 there is a rod connection 114 by which means the slight movements of roller 111 perpendicular to the web'are communicated to the armature, causing the latter to tilt in one direction or the other and thus affecting the field of force between the

legs

107 and 106 on the one hand and 107 and 108 on the other hand.

In the Wiring diagram of Fig. 6 a supply of A. C. current comes from line wires 116 and 117.

Conductors

118 and 119 lead from these line wires to a winding 120 on magnet leg 107. Windings 121 and 122 on

magnet legs

106 and 108 are placed in a series circuit 123 containing the resistance winding of a potentiometer 124. The movable contact 125 of the potentiometer 124 is connected to the grid of a rectifier tube 126; the filament of which is connected with conductor 119 and with the winding of the potentiometer 124 by a wire 1 27. The plate of tube 126; is connected to the conductor 118; through a resistance 128 across which the input of a phase shifting bridge 129 is connected. The output of this bridge is connected to the primary coil of a transformer 1 30. The secondary of transformer 130 is center-tapped with the end terminals respectively connected to the grids of gas filled rectifier tubes such as

thyratron tubes

131 and 132 The common center-tap or terminal of the secondary of transformer 130 is connected with the filament of tube 131, the plate of tube 132 and to the power wire 116, while the plate of tube 131 and the filament of tube 132 are connected to each other and through the control winding 133 of the saturable reactor 65 to the power wire 117. The reactor 65, as previously described, controls the flow of current through the

heater

62 or 96, as the case may be.

Accordingly, when the tension in the length of web b contacted by tensiometer 15 falls below a predetermined optimum and the roller 111, sometimes called a dancer roll, descends to make a greater than normal dimple in the web, armature 109 is tilted from its median position so as to approach more closely leg 106 of the magnet core andrecede from leg 108. This alters the potential on the grid of rectifier tube 126, correspondingly varying its output thereby causing'a. current flow through the phase shifting bridge and. the primary of transformer 130. This causes a corresponding change in the potentials applied to the gas filled

rectifier tubes

131 and 132, thereby causing a flow of direct current through the control coil133 of the saturable reactor 65. The direction of this current flow, for the assumed condition of web tension of therun b is such that electric current is permitted to flow through the

heater

62 or 96, thereby expanding the diameter of the pull roll and thus increasing the tension of the traveling web. The dancer roll thus rises gradually and tilts the armature 109 back to its This alters the electrical characteristics of the circuit in a manner which reduces the current through the heater, as will now be apparent. When the low tension condition is overcome and the current -through the heater is reduced and it becomes desirable to lower the temperature of the circulating liquid to its normal running temperature, this occurs automatically partly because of the fact that the temperature of the hot liquid 'isabove room temperature and partly because the traveling web wipes heat from the roll.

When the opposite condition obtains, that is when the tension on the-web rises above the predetermined optimum andthe dancer roll rises tilting the armature 109 in the opposite direction, causing it to approach leg 108 more closely than leg 106, the electrical system functions to supply direct current to the control winding 133 in the reverse direction thereby substantially preventing passage of current through saturable reactor 65, so that the temperature of the circulating liquid falls quickly to a temperature somewhat below normal running temperature with the result that the diameter of the pull roll decreases and thus relieves the tension.

The circulation of liquid is continuous during the operation of the machine. A normal temperature for the pull roll is appreciably above room temperature, that is it may be 110 or 120 F., so that if a decrease in web tension is called for the control may function effectively to bring that about. On the other hand when an increase in tension is called for the temperature of the liquid may readily be raised above the normal of 110' or 120 F., sufficiently to quickly expand the pull roll and correct the condition.

The action of the described control is prompt and effective and holds the tension of the web within close limits, which of course promotes clean printing and good register and guards against web breakage and web feeding troubles.

The roll 26 is on the down stream side of the run 11, Whereas the roll 14 is on the up stream side of the run a. In other words roll 26 is a pulling roll while roll 14 may be said to be a pushing roll so far as the run a of the web is concerned. Increasing the diameter of roll 26 will take up slack in run b, while increasing the diameter of roll 14 will cause slack in run 11. Hence control of tension in the one case to take up slack must be effected by raising the temperature of roll 26, while in the other case it must be efi'fected by lowering the temperature of roll 14. The Wiring diagram of Fig. 6 illustrates the control as applied to roll 26. As applied to the roll 14, the diagram must be understood to be modified to the extent that the connections between the tensiometer and the resistor 124 would be reversed so that the direction of current through the resistor for a given armature movement would be reversed with respect to that for the tensiometer 15. Hence for a given movement of the armature 9, which in the case of tensiometer 15' would increase the current through the

heating coil

62 or 96, the result of the same movement in the case of tensiometer 15 would be to decrease the current through the heating coil. In other words in the case of the roll 14- a downward movement for example of the small roller 111 of tensiometer 15 will decrease the current through

heating coil

62 or 96 instead of increasing it as in the case of tensiometer 15.

This reversal of action as between

tensiometers

15 and 15 may be effected also if desired by employing mechanical means in tensiometer 15 to push upwardly on rod 14 when small roller 111 descends, as by interposing a lever between roller 111 and rod 114.

While the fully automatic control above described is highly desirable and is to be preferred in most cases, there may be some special instances in which it will be desirable to omit the tensiometer and the control system actuated thereby. In other words it may be desirable in such cases to rely upon thermostatic control means for maintaining a predetermined temperature of the fluid circulated through the expandible pull rolls. In that event a regulatable thermostatic control, such as is wellknown and understood in heating systems, may be employed for maintaining a selected temperature in the circulating fluid, which in turn maintains tension in the web approximately constant for any given set of conditions. A manual setting of the thermostat is provided in order to enable the operator to vary the fluid temperature as conditions may require or his judgment may dictate.

In Fig. 7 line wires are indicated at 140 and 141 6 running to a thermostat 138 which is regulatable through a considerable range, the setting means for which may be located in the head 142 or" the thermostat, the pointer 139 indicating the temperature for which the thermostat is set to close the heating circuit.

Branch wires

143 and 144 run from line wire down to the fitting 145 of the calrod heater 62. The usual relay means between the low voltage circuit of the thermostat and the line voltage for the heater is omitted from the drawing in order to simplify the disclosure.

As illustrated in the drawing the thermostat may be set at 110 for example. When the temperature in the tank 52 falls a degree or two below that point the line circuit is completed, the calrod is energized and the temperature of the fluid in the tank rises. When it reaches a temperature of 110 or a degree or two above that point the thermostat breaks the circuit and the circulating fluid cools until the electric circuit is again closed and the cycle repeated.

Having thus described my invention, I claim:

1. In a tension control for the tension of a web traveling through a printing press, means for feeding the web through the press at printing speed comprising a pull roll the diameter of which increases with increased temperature and decreases with a drop in temperature, means for maintaining the temperature of said roll at all times at no less than a predetermined point above room temperature, and means responsive to changes in web tension for varying the temperature of said pull roll above or below said predetermined point to vary the consequent diameter of the roll.

2. In a tension control for the tension of a web traveling through a printing press, means for feeding the web through the press at printing speed comprising a hollow pull roll, the diameter of which increases with increased temperature and decreases with a drop in temperature, means for circulating fluid through said pull roll, means for maintaining the temperature of said fluid at all times at no'less than a predetermined point above room temperature, and means responsive to changes in web tension for varying the temperature of said fluid above or below said predetermined point to vary to consequent diameter of the roll.

3. In an automatic control for the tension of a web traveling through a printing press, means for feeding the Web through the press at printing speed comprising a pull roll the diameter of which increases with increased temperature and decreases with a drop in temperature, a traction roller biased toward said pull roll and means responsive to changes in web tension for varying the temperature of said pull roll and the consequent diameter of the roll.

4. 'In an automatic control for the tension of a web traveling through a printing press, means for feeding the web through the press at printing speed comprising a hollow pull roll the diameter of which increases with increased temperature and decreases with a drop in temperature, means for circulating fluid through said pull roll, and means responsive to changes in web tension for varying the temperature of the said fluid when the tension of the web is below or above a predetermined value.

5. In an automatic control for the tension of a paper web traveling through a printing press, means for feeding the web through the press at printing speed comprising a pull roll the diameter of which increases with increased temperature and decreases with a drop in temperature, and means responsive to changes in web tension for varying the temperature of said pull roll above room temperature and the consequent diameter of the roll.

6. In an automatic control for the tension of a web traveling through a printing press or other web handling machine, a hollow pull roll the diameter of which increases with increased temperature and decreases with a.

drop in temperature, means for circulating fluid through said pull roll, means for heating said fluid, to difierent temperatures above room temperature, and means responsive to changes in web tension for operating said heating means to raise or lower the temperature of the said fluid when the tension of the web is below or above a predetermined value.

7. In an automatic control for the tension of a web traveling through a printing press or other Web hand-ling machine, a pull roll the diameter of which increases with increased temperature and decreases with a drop in temperature, a tensiometer in operative relation with the web betweensaid pull roll and said printing press or other web handling machine, means for heating said. pull roll comprising an electric heating unit, a saturable reactor for supplying current to said electric heating unit, and electrical means responsive to the operation of said tensiometer for controlling the action of said saturable reactor, whereby current through the said heating unit is increased or decreased when the tension in the web is below or above a predetermined value and whereby the tension is maintained 'at all times close to said predetermined value.

'8. In an automatic control for the tension of a web traveling through a printing press or other web handling machine, a hollow pull roll the diameter of which increases with increased temperature and decreases with a dropin temperature, a traction roller cooperating therewith, a tensiorneter in operative relation with the web between said pull roll and said printing press or other web handling machine, means for circulating fluid through said pull roll, means for heating said fluid to different temperatures above room temperature comprising a tank in said fluid circulating means and an immersion type electric heating element in said tank, a saturable reactor for supplying current to said heating element, and electrical means responsive to the operation of said tensiometerfor controlling the action of said saturable reactor, whereby current through said heating element is increased or decreased when the tension in the web is below or above a predetermined value, and whereby the tension is maintained at all times close to said predetermined value.

9. In an automatic control for the tension of a web traveling through a printing press or other web handling machine, a hollow pull roll the diameter of which increases with increased temperature and decreases with a drop in temperature, -a tank, a conductor for fluid'flowing from the pull roll to the tank, a second conductor for fluid flowing from the tank to the pull roll, .a pump in one of said fluid conductors, an electric heating element in said tank, and means responsive to changes in web tension for varying the current to said heating element.

10. "In an automatic control for the tension of a web traveling through a printing press or other web handling machine, a hollow pull roll the diameter of which increases with increased temperature and decreases with a drop in temperature, a tank, a conductor for fluid flowing from the pull roll to the tank, a second conductor for fluid flowing from the tank to the pull roll, a pump in one of said fluid conductors, means for heating the fluid in said tank, and means responsive to changes in web tension for varying the action of said heating means and the consequent diameter of said pull roll.

References Cited in the file of this patent UNITED STATES PATENTS Italy June -11, 1935