US3245835A

US3245835A - Electrostatic cleaning method and apparatus

Info

Publication number: US3245835A
Application number: US314731A
Authority: US
Inventors: Gallino Robert
Original assignee: Lowe Paper Co
Current assignee: Lowe Paper Co
Priority date: 1963-10-08
Filing date: 1963-10-08
Publication date: 1966-04-12
Anticipated expiration: 1983-04-12

Description

April 12, 1966 R. GALLINO 3,245,835

ELECTROSTATIC CLEANING METHOD AND APPARATUS Filed 001:. 8, 1965 ATT NEYS United States Patent Jersey Filed Oct. 8, 1963, Ser. No. 314,731 Claims. (Cl. 134-1) The invention relates to a method and device for removing dirt from the surface of paper being processed, for example, in printing presses and the like.

In the printing trade, surface dirt which becomes attached to the paper stock is a considerable source of annoyance. The dirt or impurity may originate from the paper stock itself, from its packing, or may simply become attracted from the ambient atmosphere owing to static electricity elfects.

Various complicated methods and devices have been devised for reducing or removing surface dirt of this kind. These include complex vacuum devices and air blowers, electric generators, and the like. (Hitherto known solutions either require a source of carefully adjustable electric current, or they involve intricate mechanical-electrical devices which are costly and tedious to operate.

It is an object of the present invention to provide a method and device for removing or at least substantially reducing surface dirt in the printing trade and in similar applications, e.g., mimeographing and coating.

It is another object of the invention to avoid the drawbacks of previously known methods and devices, such as high expense, and complicated installation and use.

According to the invention, a film of plastic is laid across the paper being processed, either before or after the sheeting operation. The film is adapted to build up a static charge by frictional contact with the moving paper. The static charge produced by this expedient attracts the particles of dirt which are attached to the paper. Since the plastic film tenaciously clings to the traveling web, the surface dirt is collected and the printing press is then fed with material free from impurities.

In a preferred embodiment, a piece of plastic film is hung above the traveling paper web so that the static charge develops because of the relative movement between the stationary plastic film and the moving paper. In another embodiment, supply and take-up rolls of plastic film are provided in proximity to the paper feed, whereby the film may be moved in a direction opposite to that of the feed. Upon depletion of the supply roll, the plastic film can be re-used by switching the empty and full film rolls.

One of the important advantages of the invention is that the static charge continuously regenerates itself by the contact between the film and the paper. Furthermore, the film can be readily cleaned of the adhering dirt so that re-use is possible without added expenditure or time-consuming operations. Other objects and advantages of the invention will be appreciated and more fully understood with reference to the following detailed description, when considered with the accompanying drawing, wherein FIG. 1 is a schematic perspective view of one embodiment of the device for carrying out the novel method according to the invention;

FIG. 2 is a similar view of another embodiment of the invention; and

FIG. 3 is a schematic side elevation of a third embodiment of the device for carrying out the novel method of removing surface dirt.

In FIG. 1, a continuous paper web 10 is shown passing from the right-hand side of the drawing (supply) to the left-hand side (printing press or the like). A stationary block 12 is fastened to the machine frame or similar ele- 3,245,835 Patented Apr. 12, 1966 ment, and a supporting rod 14 extends from block 112 above the path of paper '10 substantially perpendicular to its direction of travel. A plastic film 16 is fastened to rod 14 in any conventional manner so that it hangs down and engages the surface of web 10. The frictional engagement between web 10 and film 16 produces a static charge due to the frictional drag of the ceramic clay coating on the paper. In operation, the surface dirt adhering to the untreated portion 10a of web 10 is caught by film 16 due to the static charge. The treated web portion 10b, beyond the range of contact with the film, will thus be substantially free from dirt.

FIG. 2 illustrates another embodiment of the invention. A continuous paper web 20 passes from the right to the left.

Stationary blocks

22 and 23 carry

rotatable shafts

24 and 25, respectively, which are adapted to hold a supply roll of film 27 and a take-up roll 28. Shaft 25 has a pulley 2.1 attached thereto from which it can be driven by conventional extraneous means (not shown) such as an electric motor. Additional rotatable shafts 24 and 25', held by stationary blocks 22' and 26, respectively, stretch the film so that an intermediate portion 26 remains in intimate contact with web 20. If desired, shafts 24' and 2-5 may be biased by conventional means toward the web so that sufficient, adjustable resilience will be provided between the frictionally engaging paper web and film. When all of the film has been transferred from roll 27 to roll 28, the rolls may be interchanged so that the film can be re-used.

A third embodiment of the invention is shown in FIG. 3, wherein a web of paper 30 moves in the same direction as a continuous film band 36 stretched over

rollers

37 and 38 which are rotatably mounted on

axles

34 and 35, respectively. By conventional means (not shown), film band 36 may be :made to run faster or slower than web 30. Adjustment of the engagement between film and paper, as well as regulation of the respective speeds, will alter the degree of dirt removal within prescribed limits, without physically damaging the paper surface.

Although the second embodiment discloses movement of the paper web and plastic film in opposite directions, the film may move in the same direction or be stationary, depending upon the speed difierential desired between the web and film. Movement in opposite directions has the added advantage that accumulated dirt is moved toward the supply portion of the web, rather than toward the treated, clean portion where it may adhere to the web again.

The plastic film used in accordance with the principles of the invention may the polyethylene, nylon, cellulose acetate, polyvinylidine chloride or the like. It has to be flexible enough to adhere to the paper web, and smooth enough not to roughen up the surface of delicate printing papers. In the embodiments of FIGS. 2 and 3, the atmospheric humidity prevailing at the site where the device is used can be elficiently compensated (for by judicious adjustment of the relative speed between the \film and the paper web.

Experiments have shown that best [results can be obtained by using a nylon fabric approximately 1 mil thick with 2 mils of polyethylene coating on each side.

Although schematically shown in connection with supply means for printing presses, the invention can be employed with a device attached to or forming part of paper manufacturing machinery as well. No major installation is required and the inventive device can be added with ease to any existing installation.

The foregoing disclosure relates only to preferred embodiments of the invention which is intended to include all changes and modifications of the examples described within the scope of the invention as set forth in the appended claims.

What is claimed is:

1. A method [for removing dirt particles from the surface of a web, which when rubbed against a given material produces in the latter material an electrostatic charge attracting dirt particles from the web to said given material, comprising the steps of: applying the end of a comparatively wide film of said given material across the full width of said web, with the sides of said film extending past the side edges of said web; producing relative motion between said web and said film in a direction transverse to the width of said web to rub said film against said web, whereby the static charge produced on said film by said rubbing causes the dirt particles to leave said web and adhere to said film; and maintaining said film in continuous and intimate contact with said Web during said motion so as to capture the dirt particles therebetween.

2. A method according to claim 1, wherein said relative motion is produced by holding said film stationary while said web travels therealong.

3. A method according to claim 1, wherein said relative motion is produced by moving said film at a speed different from that of the traveling web.

4. A method according to claim 3-, wherein both said web and said film move in the same direction, the speed of said film being greater than that of said web.

5. A device for removing dirt particles from the surface of a web or the like, comprising in combination, a

flexible and substantially smooth film having an end thereof extending across the entire width of said web and past the sides thereof, said film being of a material which when rubbed against said web becomes electrostatically charged to attract dirt particles firom said web, means for producing relative movement between said web and said film, to rub the latter over said web in a direction transverse to the width of said web, and means for holding said film in intimate and continuous contact with said web so that the dirt particles removed from said web due to the electrostatic charge on said film are trapped between said film and said web.

6. A device according to claim 5, wherein said means for producing relative motion consists of a structure for moving said web beneath said film and said holding means comprises a stationary rod-like member which carries said film and from which said film hangs down into engagement with said web.

7. A device according to claim 5, wherein said holding means comprises a pair of spaced-apart shafts, said film being in the [form of a strip wound on said shafts, and means vfor moving said film strip from one shaft to the other while contacting said web.

8. A device according to claim 7, wherein said holding means comprises a second pair of shafts, said film strip being guided between said shafts of the first mentioned pair over those of the second pair.

9. A device according to claim 8, wherein both said web and said film are moved in the same direction, the speed of said film being higher than that of said web.

10. A device according to claim 5, wherein said holding means comprises a pair of spaced-apart .axles, a roller on each of said axles, and wherein said film is in the form of a continuous endless strip wound around said rollers.

References Cited by the Examiner UNITED STATES PATENTS 1,947,748 2/ 1934 Van Wormer l5308 2,518,384 8/1950 Settergren 15-232 2,894,744 7/1959 Schulze 15--1.5 X 3,074,086 1/1963 Remer 151.5 3,099,856 8/1963 Eichorn et a1 15l.5 X

, FOREIGN PATENTS 1,175,749 11/1958 France.

601,456 8/ 1934 Germany.

47,998 6/1930 Norway. 340,456 9/ 1959 Switzerland.

CHARLES A. WILLMUTH, Primary Examiner.

WALTER A. SCHE'EL, Examiner.

Claims

1. A METHOD OF REMOVING DIRT PARTICLES FROM THE SURFACE OF A WEB, WHICH WHEN RUBBED AGAINST A GIVEN MATERIAL PRODUCES IN THE LATTER MATERIAL AN ELECTROSTATIC CHARGE ATTRACTING DIRT PARTICLES FROM THE WEB TO SAID GIVEN MATERIAL, COMPRISING THE STEPS OF: APPLYING THE END OF A COMPARATIVELY WIDE FILM OF SAID GIVEN MATERIAL ACROSS THE FULL WIDTH OF SAID WEB, WITH THE SIDES OF SAID FILM EXTENDING PAST THE SIDE EDGES OF SAID WEB; PRODUCING RELATIVE MOTION BETWEEN SAID WEB AND SAID FILM IN A DIRECTION TRANSVERSE TO THE WIDTH OF SAID WEB TO RUB SAID FILM AGAINST SAID WEB, WHEREBY THE STATIC CHARGE PRODUCED ON SAID FILM BY SAID RUBBING CAUSES THE DIRT PARTICLES TO LEAVE