US3731915A

US3731915A - Feed roll abrasion roller

Info

Publication number: US3731915A
Application number: US00196691A
Authority: US
Inventors: J Guenther
Original assignee: Xerox Corp
Current assignee: Xerox Corp
Priority date: 1971-11-08
Filing date: 1971-11-08
Publication date: 1973-05-08
Anticipated expiration: 1990-05-08
Also published as: JPS4855741A; NL7213337A; GB1389426A; AR194272A1; JPS5612585B2; DE2249475A1; CA966518A; BR7207646D0; BE791064A; IT970223B; FR2160088A5

Abstract

An apparatus in which an abrasive member is positioned in rubbing engagement with a moving separating and advancing means of a sheet forwarding mechanism to retain a preselected frictional force between the separating and advancing means and successive single sheets for permitting the efficient separation and advancement thereof. The foregoing abstract is neither intended to define the invention disclosed in the specification, nor is it intended to be limiting as to the scope of the invention in any way.

Description

United States Patent 1 Guenther [451 May 8,1973

[54] FEED ROLL ABRASION ROLLER [75] Inventor: Joachim Guenther, Webster, NY.

[73] Assignee: Xerox Corporation, Stamford,

Conn.

22 Filed: Nov. 8, 1971 [21] Appl. No.: 196,691

[52] U.S.Cl. ..271/36,27l/21,271/5l [51] Int. Cl. ..B65h 3/06 [58] Field of Search ..27l/36, 37, 38, 39, 271/40, 41, 21, 22, 23, 51, 52,19, 24, 42, 64

[56] 3 References Cited UNITED STATES PATENTS 984,273 2 1911 Hebert ..271 37 1,668,967 5/1928 Labombarde ....27l/37 1,956,475 4/1934 Robinson ..271/39 X Primary Examiner-Ev0n C. Blunk Assistant Examiner-Bruce H. Stoner, Jr. Attorney-James J. Ralabate et a1.

[57] ABSTRACT An apparatus in which an abrasive member is positioned in rubbing engagement with a moving separating and advancing means of a sheet forwarding mechanism to retain a preselected frictional force between the separating and advancing means and successive single sheets for permitting the efficient separation and advancement thereof.

The foregoing abstract is neither intended to define the invention disclosed in the specification, nor is it intended to be limiting as to the scope of the invention in any way.

9 Claims, 1 Drawing Figure PATENTEDMY 81m 3.731.915

- INVENTOR JOACHIM GUENTHER ATTORNEY FEED ROLL ABRASION ROLLER BACKGROUND OF THE INVENTION This invention relates to an apparatus for maintaining a sheet forwarding mechanism in condition to efficiently separate and advance a sheet from a stack of sheets, and more particularly concerns an apparatus for engaging the moving separating and advancing means of the sheet forwarding mechanism to retain a preselected frictional force between the separating and advancing means and each successive sheet to be forwarded therefrom.

It is customary to provide a sheetmaterial, such as paper, for typical copiers used in business offices. Generally the paper is of a predetermined size which advances through the copier, one sheet at a time, for suitable processing therein. Inasmuch as copies may be made at high speed, it is advantageous to stack a usable supply of paper in a sheet forwarding mechanism and to automatically advance one sheet of paper at a time to the sheet processing apparatus of the copier.

A conventional sheet forwarding mechanism is equipped with a tray member that supports a stack of sheets, separator elements at the forward end of the tray member, and a feeding mechanism having one or a plurality of rotatable feed rolls for separating and advancing the paper. The feed rolls engage the surface of the sheet to be separated and advanced from the stack. As the feed roll rotates, a frictional force is applied to the sheet of paper which separates and advances the sheet from the remainder of the stack. The surface of the feed roll engaging successive sheets must have a coefficient of friction which is sufficiently high to separate and advance successive sheets therefrom. Generally, if the coefficient of friction of feed roll surface is within a preferable range, the feed roll will operate efficiently. However, after prolonged usage the feed roll surface gradually becomes progressively smoother. This results in a progressive decrease in the coefficient of friction thereof, and, inasmuch as the normal force applied thereto during each sheet forwarding cycle is substantially constant, an ensuing reduction in the frictional force exerted on the sheet results. When the frictional force decreases beneath a critical value, the feed roll will sporadically slip on the surface of the sheet and no longer efficiently separate and advance successive sheets therefrom. Heretofore, the typical natural rubber feed roll was capable of separating and advancing about 20,000 sheets before sufficient slippage occurred between the feed roll and sheet to prevent the efficient separation and advancement thereof.

Progressive glazing" of the feed roll surface is the primary factor in reducing the coefficient of friction thereof. Glazing of the feed roll surface is usually produced by contamination or waste material becoming embedded therein. In office copiers, such as xerographic machines, the contaminants usually are in the form of paper fibers, e.g., titanium dioxide, a paper whitener, and/or toner particles. When, due to glazing, the coefficient of friction has decreased below the critical value, the feed roll starts to slip and eventually fails to perform the sheet separation and advancement function satisfactorily.

Another problem associated withfeed rolls fabricated from natural rubber is the deleterious deterioration thereof. Feed roll deterioration is due, primarily, to the reaction of the natural rubber with ozone which is normally present in xerographic copiers requiring high electrostatic fields in the operation thereof. Although the amount of ozone produced is relatively low, it nevertheless is sufficient, after a period of time, to harm the feed roll.

Accordingly, it is a primary object of the present invention to improve the efficiency of a sheet forwarding mechanism byextending the useful life of the separating and advancing means thereof.

SUMMARY OF THE INVENTION Briefly stated, and in accordance with the present invention, there is provided an apparatus for maintaining about a preselected frictional force between the separating and advancing means of a sheet forwarding mechanism and each successive sheet to be forwarded thereby.

In accordance with the present invention, the apparatus includes an abrasive member mounted movably in a support member. The support member is adapted to move the abrasive member into rubbing engagement with the outer surface portion of the separating and advancing means. In this way, the abrasive member maintains the outer surface potion of the separating and advancing means substantially free from contamination and at about a constant roughness to retain the preselected frictional force between each successive sheet and the separating and advancing means. This insures that each sheet is efficiently separated and advanced during the useful life of the mechanism.

BRIEF DESCRIPTION OF THE DRAWINGS Other objects and advantages of the present invention will become apparent upon reading the following detailed description and upon reference to the drawings, in which the FIGURE illustrated is a perspective view depicting the apparatus for maintaining the separating and advancing means of the sheet forwarding mechanism at substantially a constant roughness.

While the present invention will be described in connection with a preferred embodiment, it will be understood that it is not intended to limit the invention to that embodiment. On the contrary, it is intended to cover all alternatives, modifications and equivalents as they be included within the spirit and scope of the invention as defined by the appended claims.

DETAILED DESCRIPTION OF THE INVENTION With continued reference to the drawing, a sheet forwarding mechanism is illustrated as having an abrasive member therein for maintaining a preselected frictional force between the feed rolls thereof and successive sheets to be forwarded thereby. The abrasive member continuously engages the surface of the feed rolls to remove contaminants and maintain the roughness substantially constant during the operation of the sheet forwarding mechanism. This, in turn, insures that there is no slippage and successive sheets are separated and advanced from the sheet forwarding mechanism.

The sheet forwarding apparatus, indicated generally by the reference numeral 10, includes a tray member,

designated generally at 12, for holding a stack of sheet material, a pair of feed rolls l4 and 16 for separating and advancing successive single sheets from the stack, a registration member 18 for aligning the forwarded sheet,

forwarding rolls

20 and 22 for advancing the sheet after alignment. Feed rolls 14 and 16 are mounted in cooperating relationship with one another in front of tab members 24 and 26 which assist in separating the forwardly moving paper from the remainder of stack 28. Feed rolls l4 and 16 advance the uppermost sheet of stack 28 over tab members 24 and 26, and between

forwarding rolls

20 and 22, until the leading edge potion of the forwarded sheet engages registration member 18. This is achieved by a suitable endless belt or chain drive 30 which rotates cam 32 in the direction of arrow 34. Sector gear 36 is resiliently maintained in engagement with cam 32 by means of a suitable spring member 38. Cam 32 drives sector gear 36 in an oscillating fashion as indicated by arrow 37. Sector gear 36 meshes with pinion gear 40 to rotate pinion gear 40 in counter clockwise and clockwise directions. Since pinion gear 40 and feed rolls 14 and 16 are secured to common shaft 42, feed rolls 14 and 16 rotate in conjunction with pinion gear 40 as indicated by arrow 44. Feed rolls 14 and 16 are in intermittent rotation, and are adapted to engage the uppermost sheet of stack 28 disposed in tray member 12. Tray member 12 includes a pivotable base plate 46 on which the stack 28 is disposed. Base plate 46 is adapted to pivot so that the uppermost sheet of stack 28 engages feed rolls l4 and 16. Drive 30 rotates shaft 48 having cam 50 mounted thereon. Cam 50, in turn, drives cam follower 52, which is mounted on a common shaft 54 with tab members 24 and 26. Tab members 24 and 26, thereby, pivot in synchronism with feed rolls l4 and 16 to engage and disengage the uppermost sheet of stack 28 at the appropriate time, i.e., shaft 54 rotates in both a clockwise and counter clockwise direction as indicated by arrow 56. Forwarding roll 22 is rotated by a suitable drive (not shown). Cam 58 drives cam follower 60, which, in turn, causes connecting link 62 having shaft 66 and shaft 68 affixed thereto, to pivot in the direction of arrow 64. In this way, shaft 66, which has forwarding roll 20 mounted thereon, is adapted to move forwarding roll 20 into and out of en'- gagement with an advancing sheet passing over forwarding roll 22. The advancing sheet moves between the closely spaced forwarding rolls 20 and 22, and the leading edge potion engages registration member 18, Registration member 18 is adapted to move in upwardly and downwardly directions, as indicated by arrow 39. Link 62 pivots to move forwarding roller 20 downwardly into engagement with the advancing sheet, and simultaneously therewith, registration member 18 downwardly to disengage the leading edge potion of the advancing sheet therefrom. The sheet is, thereupon, transferred from the sheet forwarding apparatus 10. It will be appreciated that the operation of the sheet forwarding apparatus is controlled by driving means 30, which, in turn, is controlled by a suitable timing apparatus to insure the proper sequential advancement of the forwarded sheets.

Upon inspection of the FIGURE, it will be seen that tray member 12 includes a gate member 13 mounted pivotably thereon at one end thereof via hinge pin 15.

Gate member 13 is adapted to pivot about 3 or 4 in substantially a counter clockwise direction into engagement with feed rolls 14 and 16.

Having observed the details of the operation of sheet forwarding mechanism 10, attention may now be given to the specific subject matter of the present invention, an apparatus, designated generally at 70, for engaging feed rolls 14 and 16 to maintain surfaces 14a and 16a, respectively, at a substantially constant roughness and to remove contaminants therefrom. This, in turn, insures that the frictional force between successive sheets and feed rolls l4 and 16 remains at about the preselected value. Apparatus 70 includes a support member, indicated generally at 71, and an abrasive member, designated generally at 78. Support member 71 has a shaft 72 mounted in sheet forwarding apparatus 10, and a pair of coupling members 74 and 76 attached pivotably to shaft 72. Coupling members 74 and '76 have abrasive member 78 interposed therebetween and mounted rotatably therein. Abrasive member 78 includes shaft 77 interposed between and mounted rotatably on coupling members 74 and 76. Shaft 77 comprises a cylindrical member 80 having frictional means 82, such as a coating of sandpaper, affixed thereon. In addition, biasing means 84, for example, a coil spring, is adapted to prevent cylindrical member 80 from rotating in one direction while permitting cylindrical member 80 to rotate in the other direction. Coil spring 84 has one end thereof attached to coupling member 74 and is wound about shaft 77 with the other end thereof attached to cylindrical member 80. Spring 84 is prewound and yieldingly prevents feed rolls 14 and 16 from rotating abrasive member 78 in one direction. However, abrasive member 78 is free to rotate in the opposed direction. In this manner feed rolls l4 and 16 abrasively slide over sandpaper coating 82 to remove contaminants therein and maintain the roughness thereof substantially constant. Spring coil 84 is prewound such that cylindrical member 80 rotates freely when feed rolls 14 and 16 rotate counter clockwise to buckle the uppermost sheet of stack 28 for separation thereof while it yieldingly prevents rotation of cylindrical member 80 when feed rolls l4 and 16 rotate in a clockwise direction to advance the uppermost sheet of stack 28 therefrom.

Furthermore, it will be appreciated that coupling members 74 and 76 are mounted pivotably on shaft 72. In this manner, coupling members 74 and 76 having cylindrical member 80 interposed therebetween are pivoted in substantially a downwardly direction under the force of gravity to locate sandpaper coating 82 in engagement with surface portions and 16a of feed rolls l4 and 16, respectively. When feed rolls l4 and 16 rotate in a clockwise direction, surface portions 14a and 16a thereof are moved across the substantially stationary sandpaper coating 82. Sandpaper coating 82 abrades surface portions 140 and 16a of the respective feed rolls 14 and 16 and prevents glazing of these surfaces. Moreover, the deleterious deterioration of the feed roll caused by ozone is minimized by the continuous removal of material therefrom by abrasive member 78.

By way of example, the feed rolls are preferably an elastomer such as natural rubber, synthetic rubber or Mearthane, and have a coefficient of friction preferably ranging from about 2.36 to about 2.97. Preferably, the sandpaper coating 82 affixed to cylindrical member 80 minimizes the amount of material removed from the natural rubber feed roll while insuring that the coefficient of friction is maintained substantially constant. An appropriate grit sandpaper must be judiciously selected. An inappropriate selection such as type 325 sandpaper coating causes a diameter decrease of about 0.014 inches in the feed rolls after forwarding 25,000 sheets, or 0.070 inches thereof after forwarding 125,000 sheets. in addition, when type 325 sandpaper was used, small rubber particles tended to abrade from the feed rolls and interfere with the operation of the sheet forwarding apparatus. Whereas a suitable selection such as a type 600 sandpaper coating maintained the coefficient of friction at about 2.97 after forwarding approximately 50,000 sheets without any recordable change in the diameter of the feed roll. After forwarding 100,000 sheets the coefficient of friction was only reduced by about 4 percent and the diameter of the feed roll decreased only by about 0.008 inches. This clearly indicated that feed roll glazing could be prevented through the utilization of an abrasive member for removing contamination from the feed roll in order to maintain the roughness thereof substantially constant, i.e., the coefficient of friction is maintained substantially constant at a preselected value. As hereinbefore indicated, the biasing means or coil spring 84 is prewound, in this way, when feed rolls l4 and 16 rotate in a counter clockwise direction to buckle the uppermost sheet of stack 28, the spring is unwound and there is no rubbing action on feed rolls l4 and 16. However, when feed rolls 14 and 16 rotate in a clockwise direction, to advance the uppermost sheet from stack 28, coil spring 84 is wound and yieldingly prevents cylindrical member 80 from rotating. Thus, under these circumstances, there is a rubbing action between sandpaper coating 82 and feed rolls 14 and 16. The characteristics of the spring, in order to insure that the cylindrical member 80 is free to rotate when feed rolls l4 and 16 buckle the sheet and prevent rotation when feed rolls 14 and 16 advances the sheet, are as follows: preferably coil spring 84 should have an inner diameter of 0.371 inches; a wire diameter of 0.020 inches; and a free length of 0.130 inches with about four turns. The spring depicted in the drawing is right handed. While the invention has been described in connection with a coil spring, one skilled in the art will appreciate that the invention is not necessarily so limited and that other suitable means such as a retractable stop pin may be provided for preventing the cylindrical member from rotating in one direction while permitting the cylindrical member to rotate in the opposite position.

In recapitulation, the present invention maintains a preselected frictional force between the feed rolls and each successive sheet to be advanced by removing contamination such as paper fibers and/or toner particles embedded therein and maintaining the roughness thereof substantially constant. Moreover, due to the intermittent rubbing of the surface of the feed rolls, ozone is less likely to penetrate the surface thereof and damage the feed rolls. Hence the apparatus. of the present invention has been found to substantially increase the useful life of natural rubber feed rolls.

Thus, it is apparent that there has been provided in accordance with the present invention, apparatus that fully satisfies the object, aims and advantages set forth above. While the invention has been described in con- 5 junction with specific embodiments thereof, it is evident that many alternatives, modifications and variations will be apparent to those skilled'in the art in light of the foregoing description. Accordingly, it is intended to embrace all such alternatives, modifications and variations as fall within the spirit and broad scope of the appended claims.

What is claimed is:

1. An apparatus for forwarding successive sheets from a stack of sheet material in a storage compartment, including:

means for separating and advancing successive sheets from the stack, said separating and advancing means having an outer surface portion thereof contacting each successive sheet to be forwarded therefrom;

a support member mounted movably in the storage compartment;

a cylindrical member mounted rotatably on said support member, said support member being pivotable to gravity urge said cylindrical member toward said separating and advancing means positioning said cylindrical member in rubbing engagement therewith; and

biasing means for yieldingly preventing said cylindrical member from rotating in one direction while permitting said cylindrical member to rotate in the opposed direction, the rubbing of said cylindrical member against said separating and advancing surface when said cylindrical member is substantially prevented from rotating maintaining the roughness of said separating and advancing means substantially constant to retain about a preselected frictional force between said separating and advancing means and each successive sheet permitting continuously efficient separation and advancement thereof.

2. An apparatus as recited in claim 1, wherein said cylindrical member includes frictional means for sliding abrasively over the outer surface portion of said separating and advancing means when said biasing means yieldingly prevents said cylindrical member from rotating.

3. An apparatus as recited in claim 2, wherein said frictional means includes a sandpaper coating disposed on the outer peripheral surface of said cylindrical member.

4. An apparatus as recited in claim 2, wherein said cylindrical member maintains the coefficient of friction of said separating and advancing means preferably in the range of from about 2.35 to about 2.97.

5. An apparatus for maintaining the peripheral surface portion of a rotatable feed roll used in a sheet forwarding mechanism at about a preselected surface finish, including:

a movable support member cooperating with the sheet forwarding mechanism;

a cylindrical member mounted rotatably on said support member, said support member being pivotable to gravity urge said cylindrical member toward the feed roll positioning said cylindrical member in rubbing engagement therewith; and

biasing means for yieldingly preventing said cylindrical member from rotating in one direction while permitting said cylindrical member to rotate in the opposed direction the rubbing of said cylindrical member against said feed roll when said cylindrical member is substantially prevented from rotating maintaining the roughness of the feed roll substantially constant to retain about a preselected frictional force between the feed roll and each successive sheet permitting continuously efficient separation and advancement thereof.

6. An apparatus as recited in claim 5, wherein said cylindrical member includes frictional means for sliding abrasively over the outer peripheral surface of the feed roll when said biasing means prevents said cylindrical member from rotating.

7. An apparatus as recited in claim 6, wherein said frictional means includes a sandpaper coating disposed on the outer peripheral surface of said cylindrical member.

8. An apparatus as recited in claim 6, wherein said cylindrical member maintains the coefficient of friction of the feed roll preferably in the range of from about 2.35 to about 2.97.

9. An apparatus for seriatim feeding of sheets from a stack of sheet material housed in a storage compartment, including:

a support member mounted movably in the storage compartment;

an abrasive roller mounted rotatably on said support member, said support member being movable to position said abrasive roller in continuous engagement with the outer surface portion of said separating and advancing means; and

means for controlling the rotation of said abrasive roller relative to said separating and advancing means, said control means being adapted to substantially prevent said abrasive roller from rotating in one direction while permitting said abrasive roller to rotate in the opposed direction, said abrasive roller, when substantially prevented from rotating sliding abrasively over the outer surface portion of said separating and advancing means, thus maintaining the roughness of said separating and advancing means substantially constant to retain about a preselected frictional force between said separating and advancing means and each successive sheet permitting continuously efficient separation and advancement thereof.

Claims

1. An apparatus for forwarding successive sheets from a stack of sheet material in a storage compartment, including: means for separating and advancing successive sheets from the stack, said separating and advancing means having an outer surface portion thereof contacting each successive sheet to be forwarded therefrom; a support member mounted movably in the storage compartment; a cylindrical member mounted rotatably on said support member, said support member being pivotable to gravity urge said cylindrical member toward said separating and advancing means positioning said cylindrical member in rubbing engagement therewith; and biasing means for yieldingly preventing said cylindrical member from rotating in one direction while permitting said cylindrical member to rotate in the opposed direction, the rubbing of said cylindrical member against said separating and advancing surface when said cylindrical member is substantially prevented from rotating maintaining the roughness of said separating and advancing means substantially constant to retain about a preselected frictional force between said separating and advancing means and each successive sheet permitting continuously efficient separation and advancement thereof.

5. An apparatus for maintaining the peripheral surface portion of a rotatable feed roll used in a sheet forwarding mechanism at about a preselected surface finish, including: a movable support member cooperating with the sheet forwarding mechanism; a cylindrical member mounted rotatably on said support member, said support member being pivotable to gravity urge said cylindrical member toward the feed roll positioning said cylindrical member in rubbing engagement therewith; and biasing means for yieldingly preventing said cylindrical member from rotating in one direction while permitting said cylindrical member to rotate in the opposed direction the rubbing of said cylindrical member against said feed roll when said cylindrical member is substantially prevented from rotating maintaining the roughness of the feed roll substantially constant to retain about a preselected frictional force between the feed roll and each successive sheet permitting continuously efficient separation and advancement thereof.

9. An apparatus for seriatim feeding of sheets from a stack of sheet material housed in a storage compartment, including: means for separating and advancing successive sheets from the stack, said separating and advancing means having an outer surface portion thereof contacting each successive sheet to be forwarded therefrom; a support member mounted movably in the storage compartment; an abrasive roller mounted rotatably on said support member, said support member being movable to position said abrasive roller in continuous engagement with the outer surface portion of said separating and advancing means; and means for controlling the rotation of said abrasive roller relative to said separating and advancing means, said control means being adapted to substantially prevent said abrasive roller from rotating in one direction while permitting said abrasive roller to rotate in the opposed direction, said abrasive roller, when substantially prevented from rotating sliding abrasively over the outer surface portion of said separating and advancing means, thus maintaining the roughness of said separating and advancing means substantially constant to retain about a preselected frictional force between said separating and advancing means and each successive sheet permitting continuously efficient separation and advancement thereof.