GB2128963A

GB2128963A - Sheet inverting device

Info

Publication number: GB2128963A
Application number: GB08230250A
Authority: GB
Inventors: Albert Ralph Clark; William August Ernst; James Edward Self; Svetislav Mitrovich
Original assignee: Mead Corp
Current assignee: Mead Corp
Priority date: 1982-10-22
Filing date: 1982-10-22
Publication date: 1984-05-10
Also published as: GB2128963B

Abstract

A sheet inverter (for reversing direction of travel of sheets) includes input and output transport conveyors (40, 68) and a sheet receiving tray (90). Sheet deflectors (114) are provided to deflect portions of a sheet (100) as it leaves the input transport conveyor (40) and moves into the tray (90), thus increasing its beam strength. A reversal drive arrangement, including a drive roller (122) within a vacuum plenum, contacts a sheet supplied to the tray (90) and moves the sheet into engagement with the sheet output transport conveyor (68). By adding beam strength to a sheet entering the tray, a second sheet may be supplied to the tray prior to complete removal of the previously inverted sheet. <IMAGE>

Description

SPECIFICATION Sheet inverting device The present invention relates to a sheet handling device and, more particularly, to a device for inverting a sheet carried by a sheet transport conveyor. It is common that inversion devices are required in various types of sheet processing systems and a number of devices have been developed which perform this sheet inversion process. In one such device, a sheet of paper is diverted from a belt conveyor onto a guide member by means of vacuum rollers cooperating with and spaced along the guide member. After the sheet has been completely removed from the beit, the direction of rotation of the vacuum rollers is reversed and the sheet returned to the belt such that the edge of the sheet which was previously the trailing edge now becomes the leading edge.Such an inverter device is somewhat limited in possible applications in that successive sheets carried by the belt must be widely spaced apart in order to provide sufficient time for a sheet to be removed completely from the sheet guide and returned to the belt prior to the application of the next succeeding sheet to the inverter device.

In a second type of inverter device, a vacuum transport receives sheets stripped from a conveyor. After a sheet has been completely removed from the conveyor and is positioned on the vacuum transport, the direction of movement of the vacuum transport is reversed so that the sheet is reapplied to the conveyor with the trailing edge of the sheet becoming the leading edge. As with the first device, this device is limited in the speed it which it can invert sheets in that a sheet must be completely removed from the inverter prior to the application of the next successive sheet to the inverter. Additionally, the second inverter device requires that a mechanically actuated deflector finger assembly be moved into contact with the sheet at its leading edge to deflect the sheet away from the conveyor.It will be appreciated that in certain instances such mechanical deflection may cause damage to the leading edge of the sheet.

In a third, generally similar type of sheet reversing device, a sheet is transported into a thin, rectangular sheet receiving pocket by a roller arrangement. The document is then withdrawn from the pocket by the roller arrangement such that the leading edge of the sheet emerging from the pocket is the edge that was trailing during insertion. Movement of a sheet within the rectangular pocket may be controlled pneumatically.

A roller arrangement for withdrawing a sheet from the pocket may preferably corrugate the sheet in a direction perpendicular to its direction of movement such that the beam strength of the sheet is increased. The sheet therefore does not tend to be carried around the sheet driving rollers. Such a device is limited in that a sheet must be completely removed from the rectangular pocket before the next successively presented sheet may be inserted into the pocket. Additionally, the leading edge of a sheet moving into the pocket strikes the end of the pocket and, as a consequence, the leading edge of a sheet may be damaged.

Accordingly, it is seen that there is a need for a simple sheet inverter device which is capable of handling the inversion of a succession of sheets at a high rate of speed, with the sheets being presented rapidly to the inverter device.

The invention provides a device for inverting a sheet including a sheet input transport means for transporting a sheet along an input path, and a sheet output transport means for transporting a sheet along an output path extending beneath the input path in a direction generally opposite to the input path. A sheet supporting surface is defined intermediate the input and output paths and is positioned for receiving a sheet which has been discharged by the sheet input transport means. A reversal drive means engages a sheet deposited on the surface by the sheet input transport means and moves the sheet into engagement with the output transport means. A deflector means is positioned adjacent the sheet input transport means for deflecting a portion of a sheet transported by the sheet input transport means.The sheet is distorted by the deflector means into a nonplanar shape to provide beam strength for the sheet as it leaves the sheet input transport means.

The reversal drive means may include means defining an opening in the surface, roller means mounted in the opening for contacting the lower surface of a sheet supported on the surface, and means for supplying a partial vacuum to the opening to hold a sheet against the roller means. The reversal drive means may further include means for rotating the roller means in a direction such that a sheet engaged thereby is transported toward the sheet output transport means.

The device may further include means defining at least one vacuum port in the surface and means supplying a partial vacuum to the vacuum port, whereby movement of a sheet on the surface over the vacuum port is retarded by the partial vacuum. A plurality of such vacuum ports may be provided in the surface with a partial vacuum supplied to each of the vacuum ports. A sheet retarding roller may be mounted in each of said vacuum ports and connected to a clutch arrangement which permits free rotation of said braking wheels as said sheet is transported toward the sheet output transport means, while preventing rotation of the braking wheel in the opposite direction.

A method of inverting a sheet according to the present invention comprises the steps of: (a) providing a sheet supporting tray having a first end thereof open to receive a sheet and to permit subsequent removal of the sheet therefrom; (b) moving a sheet along an input sheet path towards the first end of the tray while supporting the sheet in a plane parallel to the direction of movement of the sheet until the sheet extends over the tray at the first end of the tray; (c) deflecting a portion of the sheet out of the plane as the sheet extends over the tray so as to provide the sheet with beam strength; and (d) thereafter, removing the sheet from the first end of the tray in a direction substantially opposite to the direction of movement of the sheet into the tray.

The step of deflecting a portion of the sheet may include the step of deflecting the lateral edges of the sheet generally upward to curve the sheet laterally thereacross.

The method may further comprise the step of supplying a partial vacuum to an opening in the tray adjacent the first end thereof for attracting the trailing edge of the sheet to the tray as the sheet leaves the input sheet path.

The step of removing the sheet from the first end of the tray may include the step of rotating one or more rollers mounted in the opening such that the sheet contacts the roller or rollers and is transported out of the first end of the tray.

The method may also include the step of supplying a partial vacuum to a port in the tray remote from the first end thereof to attract the leading edge of the sheet to the tray as the sheet leaves the input sheet path.

Accordingly, it is seen that it is an object of the present invention to provide a device and method for inverting a sheet in which the sheet is deflected into a nonplanar shape as it leaves a sheet transport and passes into a sheet receiving tray, thereby providing the sheet with beam strength; to provide such a device and method in which a reversal arrangement is provided for transporting a sheet out of the tray; and to provide such a device and method in which sheets may be reversed without a substantial time delay between presentation of successive sheets.

The invention will now be further described, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a perspective view of one embodiment of the sheet inverting device, showing delivery of a sheet thereto; and Figures 2a-2e are views of the sheet inverting device illustrating its method of operation.

Reference is made to Fig. 1 which illustrates the sheet inverting device of the present invention. A sheet input transport is provided for transporting a sheet along an input path in a direction indicated by arrow 72. The sheet input transport means includes belts 40, extending around roller 44, which cooperates with vacuum plenum 46. Plenum 46 defines a plurality of holes 74 between the belts and receives a partial vacuum supplied thereto via a vacuum line (not shown). The partial vacuum draws sheets downward against belts 40 so that the sheets are engaged by the belts and move therewith.

A sheet output transport means includes belts 68 (Figs. 2a-2e) which extend around rollers 78, 82, 84, and 108, for transporting a sheet along an output path in the direction of arrow 86. The direction of the output path is generally opposite to and extends beneath the direction of the input path.

Positioned adjacent the sheet input transport means and the sheet output transport means is a sheet supporting tray 90 which defines the sheet supporting surface 64 and which includes a pair of side walls 92 and 94.

Walls 92 and 94 are positioned on opposite sides of the surface 64 and extend substantially parallel to the output path. If desired, the side walls 92 and 94 may be inclined by an angle of approximately 5t with respect to vertical such that they converge toward surface 64. The side walls therefore tend to position a sheet laterally as the sheet moves onto surface 64, as more fully described below.

The reversal drive means preferably includes rollers 66, the tops of which are slightly above the level of surface 64. The rollers 66 engage a sheet deposited on surface 64 by the sheet input transport means and move the sheet into engagement with the sheet output transport means, including moving belts 68. Rollers 66 are mounted in openings 96, defined by plate 98. Plate 98 defines a portion of surfaces 64 and rollers 66 contact the lower surface of a sheet 100 supported on surface 64. Rollers 66, preferably formed on an elastomeric material, are mounted to be driven by shaft 1 02. Shaft 102 is driven by belt 104 extending between pulley 106 and roller 108. As a consequence, rollers 66 are driven in synchronism with belts 68.

Plate 98 defines the top of a vacuum plenum 110 to which a partial vacuum is supplied via vacuum line 11 2. This partial vacuum forces a sheet on surface 64 downward for secure engagement by rollers 66; as a consequence, a sheet on surface 64 is engaged by rollers 66 without the need for opposing pinch rollers. If desired, a vacuum roller of the type defining a plurality of holes in its surface, and having a partial vacuum supplied to an internal roller cavity, may be substituted for the rollers 66.

A deflector means, comprising a pair of sheet contacting members 114, is mounted on the top of plenum 46 and deflects a portion of the sheet 100 transported by the input transport means. As described more fully below, the deflector means distorts the sheet into a nonplanar shape to provide beam strength for the sheet. Each of the members 114 defines a sheet contacting edge 11 6 which is inclined at an angle, such as 5 , to the direction of sheet movement along the input path. The edges 11 6 are positioned to contact a sheet adjacent opposite lateral edges of a sheet as the sheet moves along the input path.

The input path of the sheet along the sheet input transport means is inclined downward with respect to the sheet supporting surface 64. The sheet supporting surfaces is inclined approximately 6 9" with respect to horizontal.

Additionally, the input path is inclined approximately 6 io with respect to horizontal. As a consequence, the input path and the output path define an included angle therebetween of approximately 1 3 Q'.

A plurality of vacuum ports 118 and 11 9 in the surface 64 communicate with vacuum plenums to which a partial vacuum is supplied via vacuum line 1 20. As a sheet of paper moves onto surface 64, its leading edge passes over vacuum ports 118 and 119. A partial vacuum is applied through ports 11 8 when 11 inch paper is inverted, while the partial vacuum is applied through ports 11 9 when 14 inch paper is inverted. Movement of the sheet is retarded by the application of a partial vacuum to the bottom surface of the sheet.In order to provide further retardation of the movement of a sheet as the sheet moves onto the surface 64, a plurality of elastomeric rollers 1 22 are mounted such that they extend partially through the openings 118 and 119, slightly above the level of surface 64. Rollers 1 22 are connected to unidirectional clutch mechanisms which permit them to rotate freely generally counterclockwise, as seen in Fig. 1, but prevents clockwise rotation of the rollers. As a consequence, movement of a sheet 100 to the right is limited when the sheet is engaged by the rollers 122, but movement of a sheet to the left, as indicated by arrow 86 in Fig. 1, is freely permitted.

The method of sheet inversion of the present invention is illustrated in Figs. 2a-2e.

The side walls 92 and 94 have been removed from the tray 90 in Figs. 2a-2e for purposes of clarity in illustrating the operation of the device. As seen in Fig. 2a, a sheet 100 is supplied by the sheet input transport means to the inverter device. The sheet 100 moves along the sheet input path toward the tray 90, while supported in a plane parallel to the direction of movement by the vacuum belt transport arrangement including belts 40.

The lateral edges of the sheet 100 are deflected upward by members 114 as the sheet moves over the edges 11 6 such that it is distorted into a nonplanar, generally curved cross-sectional configuration. As seen in Fig.

2b, deflecting sheet 100 out of its plane of movement as it extends over the tray 90 provides the sheet with beam strength. This prevents the sheet 100 from bending in a direction perpendicular to its direction of movement as it passes out over the roller 44, unsupported by the belts 40. It will be appreciated that the lateral edges of the sheet must be deflected sufficiently to provide this deflection. For this purpose the members 11 4 extend upward by approximately T inch above the level of belts 40. If desired, greater sheet deflection may be provided.

As the leading edge of the sheet 100 contacts the surface 64, and the sheet continues to move off of the sheet input transport means, the leading edge of the sheet covers opening 118 or 11 9 and contacts rollers 122 extending through the covered openings. Because of the clutch mechanisms to which they are attached, rollers 122 do not rotate in a clockwise direction as seen in Figs. 2a-2e. As a result of the friction between the sheet 100 and the rollers 122, further movement of the sheet after it has left the input transport means is prevented.

As the trailing edge of the sheet 100 leaves the vacuum belt transport, the edge drops down onto the surface 64 in a position illustrated in Fig. 2c. It will be appreciated that the rate at which the trailing edge of sheet 100 falls onto surface 64 is a function of the weight and stiffness of the sheet and, also, of the partial vacuum supplied to the plenum 110 via vacuum line 112.

Rollers 66 are rotated by pully 106 mounted on shaft 102. Rotation of the rollers 66 occurs continuously in a counterclockwise direction as seen in Fig. 2c. As a consequence, as soon as the trailing edge of sheet 100 contacts the rollers 66 and is pulled against the rollers by the partial vacuum in plenum 110, the sheet is driven to the left, toward the belts 68. Simultaneously, the next successively presented sheet 100', shown in Fig. 2c, travels along the input path and contacts members 11 4. Since the beam strength of sheet 100' is substantially increased by deflecting it into a curved crosssectional shape as shown in Fig. 2d, sheet 100' can be moved into tray 90 before sheet 100 is completely removed from the tray without any contact between sheets 100 and 100'.

As sheet 100 is moved out of tray 90, it is engaged by the output transport means, including belts 68, as shown in Fig. 2e. It will be noted that the edge of each sheet which was previously trailing is, at this point the leading edge.

If the spacing between two sheets successively presented for inversion is undesirably close, the inverter device of the present invention tends to separate the sheets apart as they leave the inverter along the sheet output path.

As seen in Fig. 2d, the trailing edge of a sheet 100 covers the vacuum openings 96 during at least a portion of the time during which the next successive sheet 100' is supplied to tray 90. The closer together the sheets 100 and 100', the longer the time during which sheet 100 covers openings 96 as sheet 100' moves into tray 90. As a consequence, the time required for the trailing edge of the second sheet 100' to fall onto the rollers 66 increases as the spacing between sheets 100 and 100' decreases. Therefore, a substantially increased time for the trailing edge of sheet 100' to fall onto rollers 66, resulting from too close a spacing between sheets 100 and 100', allows a substantially greater period of time for the sheet 100 to travel away from the inverter device along the output path before the sheet 100' is supplied to the output path. The spacing between the two successive sheets is therefore increased.

It should be noted that the present invention is configured such that no mechanical paper stops are needed for registering either the leading or trailing edges of the sheets as they are reversed. Additionally, successively inverted sheets may be spaced very closely apart without coming into contact with each other during inversion.

While the method herein described, and the form of apparatus for carrying this method into effect, constitute preferred embodiments of the invention, it is to be understood that the invention is not limited to this precise method and form of apparatus, and that changes may be made in either without departing from the scope of the invention.

Claims

1. A sheet handling device including sheet input transport means for transporting a sheet along an input path, sheet output transport means for transporting a sheet along an output path in a direction generally opposite to said input path, said output path extending beneath said input path, and a sheet inverter for receiving a sheet from said input path and delivering the sheet to said output path in an inverted orientation, characterized in that said sheet inverter comprises:: means defining a sheet supporting surface intermediate said input and output paths and positioned for receiving a sheet which has been discharged by said sheet input transport means, reversal drive means for engaging a sheet deposited on said surface by said sheet input transport means, and for moving said sheet into engaement with said sheet output transport means, and deflector means, adjacent said sheet input transport means, for deflecting a portion of a sheet transported by said sheet input transport means, whereby said sheet is distorted into a nonplanar shape to provide beam strength therefor as said sheet leaves said sheet input transport means.

2. The device of claim 1 further characterized in that said input path is inclined downward with respect to said sheet supporting surface.

3. The device of claim 1 further characterized in that said surface is aligned with said output path.

4. The device of claim 2 further characterized in that said input path and said sheet supporting surface defines an included angle therebetween in the range of approximately 6 8" to 18 .

5. The device of claim 4 further characterized in that said included angle is approximately 13 > .

6. The device of claim 1 further characterized in that said reversal drive means comprises: means defining an opening in said surface, roller means mounted in said opening for contacting the lower surface of a sheet supported on said sheet supporting surface, means for supplying a partial vacuum to said opening to hold a sheet against said roller means, and means for rotating said roller means in a direction such that a sheet engaged thereby is transported toward said sheet output transport means.

7. The device of claim 1, further characterized by means defining at least one vacuum port in said surface, and means supplying a partial vacuum to said vacuum port, whereby movement of a sheet on said surface over said vacuum port is retarded by said partial vacuum.

8. The device of claim 6, further characterized by: sheet retarding roller means mounted in said vacuum port for contacting a sheet supplied to said sheet supporting surface, and clutch means, connected to said sheet retarding roller means, for permitting rotation of said sheet supporting roller means by a sheet in contact therewith as said sheet is transported by said reversal drive means into engagement with said sheet output transport means and for preventing rotation of said sheet supporting roller means by a sheet in contact therewith as said sheet is discharged by said sheet input transport means and received on said sheet supporting surface.

9. The device of claim 7 further characterized by means defining a plurality of vacuum ports in said surface and in which a partial vacuum is supplied to said plurality of vacuum ports.

1 0. The device of claim 1 further characterized in that said deflector means comprises a pair of sheet contacting members, each such member defining a sheet contacting edge inclined at an angle to the direction of sheet movement along said input path, said edges being positioned to contact opposite lateral edges of a sheet moving along said input path so as to deflect said lateral edges of said sheet.

11. The device of claim 9 further characterized in that each of said sheet contacting edges is inclined to the direction of sheet movement along said input path.

1 2. The device of claim 1 further characterized by a pair of side walls positioned on opposite sides of said surface and extending substantially parallel to said output path, said side walls being inclined such that they converge toward said surface to position a sheet laterally as said sheet moves onto said surface.

1 3. A method of inverting a sheet, comprising the steps of: providing a sheet supporting tray having a first end thereof open to receive a sheet and to permit subsequent removal of said sheet therefrom, moving a sheet along an input sheet path towards said first end of said tray while supporting said sheet in a plane parallel to the direction of movement thereof until said sheet extends over said tray at said first end of said tray, deflecting a portion of said sheet out of said plane as said sheet extends over said tray so as to provide said sheet with beam strength, and thereafter removing said sheet from said first end of said tray in a direction substantially opposite to the direction of movement of said sheet into said tray.

1 4. The method of claim 1 3 in which the step of deflecting a portion of said sheet includes the step of deflecting the lateral edges of said sheet generally upward to curve said sheet laterally thereacross.

1 5. The method of claim 1 3 further comprising the step of supplying a partial vacuum to an opening in said tray adjacent said first end thereof for attracting the trailing edge of said sheet to said tray as said sheet leaves said input sheet path.

16. The method of claim 1 5 in which the step of removing said sheet from said first end of said tray comprises the step of rotating a roller mounted in said opening such that said sheet contacts said roller and is transported out of said first end of said tray.

1 7. The method of claim 1 3 further comprising the step of supplying a partial vacuum to a port in said tray remote from said first end thereof to attract the leading edge of said sheet to said tray as said sheet leaves said input sheet path.

1 8. A sheet inverter device substantially as hereinbefore described with reference to the accompanying drawings.

19. A method of inverting a sheet substantially as hereinbefore described with reference to the accompanying drawings.