Method for aligning sheet in feeder of sheet processing machine

Abstract

To provide a method for adjusting position of sheet in a feeder of a sheet processing machine which increases productivity of the machine.SOLUTION: In order to convey a sheet in a conveyance direction (6) by a first drive roller (12) and a first counter pressure roller cooperating with the first drive roller (12) and by a second drive roller (14) and a second counter pressure roller cooperating with the second drive roller (14) to a sheet conveyance device and to adjust position to a side at that time, in a first step, the sheet is sandwiched between the first drive roller and the first counter pressure roller and between the second drive roller and the second counter pressure roller, and a carriage (21) on which the first drive roller (12) and the second drive roller (14) are supported is caused to travel together with the sandwiched sheet in a first direction transverse to the conveyance direction (6), thereby adjusting the position of the sheet to the side.SELECTED DRAWING: Figure 5b

Description

Technical Field

[0001] The present invention relates to a method for adjusting the position of a sheet in a feeder of a machine for processing sheets, the method comprising conveying the sheet in a conveying direction to a sheet conveying device by a first driving roller and a first opposing pressure roller cooperating with the first driving roller, and by a second driving roller and a second opposing pressure roller cooperating with the second driving roller, and performing a lateral position adjustment therebetween.

[0002] Such a method is described in European Patent Application Publication No. 1110888. In the prior art method, a large gap is required between consecutive sheets, which reduces productivity.

[0003] An object of the present invention is to provide a method for adjusting the position of a sheet in a feeder of a machine for processing sheets, which increases the productivity of the machine.

[0004] This problem is a method for adjusting the position of a sheet in a feeder of a machine for processing the sheet, the method comprising conveying the sheet in a conveying direction to a sheet conveying device by a first driving roller and a first opposing pressure roller cooperating with the first driving roller, and by a second driving roller and a second opposing pressure roller cooperating with the second driving roller, and adjusting the position laterally during this conveyance, wherein in a first step, the sheet is sandwiched between the first driving roller and the first opposing pressure roller and between the second driving roller and the second opposing pressure roller, and the carriage on which the first driving roller and the second driving roller are supported is run in a first direction transverse to the conveying direction together with the sandwiched sheet, thereby adjusting the position of the sheet laterally; in a second step, after the sheet has been captured by the sheet conveying device and before the carriage provided with the first driving roller and the second driving roller is run back in a second direction opposite to the first direction, the first opposing pressure roller is lifted from the sheet on the first driving roller and the second opposing pressure roller is lifted from the same sheet on the second driving roller; and in a third step, while the carriage is already being run back in the second direction, the method is characterized in that the non-sandwiched sheet still remains in the region between the first driving roller and the first opposing pressure roller and in the region between the second driving roller and the second opposing pressure roller.

[0005] When the method according to the invention is used, the spacing between successive sheets can be reduced. Thereby, the productivity of the machine is improved.

[0006] The improved form will be apparent from the description of the following embodiments and the accompanying drawings.

Brief Description of the Drawings

[0007]

Fig. 1a

Fig. 1b

Fig. 2a

Fig. 2b

Fig. 3a

Fig. 3b

Fig. 4a

Fig. 4b

Fig. 5a

Fig. 5b

Fig. 6a

Fig. 6b

Fig. 7

Fig. 8

Fig. 9a

Fig. 9b

Fig. 9c

Fig. 10

Fig. 11

[0008] In FIGS. 1a and 1b, the position adjusting device 1 is shown in a side view (FIG. 1a) and a plan view (FIG. 1b). The position adjusting device 1 belongs to the feeder 2 of the machine 3 for processing sheets. The machine 3 is a digital printing press having a printing station called an image forming section 4. The feeder 2 conveys a sheet 5 to be printed in the image forming section 4 in a conveying direction 6 to the image forming section 4. In this case, the sheet 5 travels in a conveying gap 8 formed by these guide plates 7 between the guide plates 7 parallel to each other. The sheet 5 is moved in the conveying direction 6 by a series of conveying devices 9. Each conveying device 9 consists of two roller pairs, and these roller pairs are arranged offset from each other in a direction transverse to the conveying direction 6. The roller pairs come into contact with the sheet 5 during conveyance, and for this purpose, windows through which the roller pairs are engaged are machined in the guide plates 7.

[0009] The position adjusting device 1 has a first roller pair 10 and a second roller pair 11. The first roller pair 10 consists of a first driving roller 12 and a first opposing pressure roller 13, and the second roller pair 11 consists of a second driving roller 14 and a second opposing pressure roller 15. In FIG. 1b, for the sake of clarity of the drawing, the opposing pressure rollers located above the conveying device 9 as well as the first opposing pressure roller 13 and the second opposing pressure roller 15 of the position adjusting device 1 are not shown, and the first opposing pressure roller 13 and the second opposing pressure roller 15 can be confirmed in FIG. 7.

[0010] The drive roller located below the conveying device 9 and the drive rollers 12, 14 of the position adjusting device 1 are driven by electric motors. Both drive rollers of each conveying device 9 are driven by one common motor. In contrast, the first drive roller 12 of the position adjusting device 1 is rotationally driven by the first motor 16, and the second drive roller 14 is rotationally driven by the second motor 17. When the first drive roller 12 and the second drive roller 14 rotate in synchronization with each other, they cause the sheet 5 to be fed in the conveying direction 6, and in this case, the sheet 5 is not rotated in the sheet conveying plane 18. The sheet conveying plane 18 is defined by the guide plate 7.

[0011] When the sheet 5 is positioned inclined relative to the conveying direction 6, it is necessary to rotate the sheet 5 about a vertical axis perpendicular to the conveying plane 18, that is, it is necessary to correct the inclined position of the sheet 5. To cause this rotation, the first drive roller 12 and the second drive roller 14 are rotated out of synchronization with each other. For example, the first drive roller 12 is rotated at a lower speed than the second drive roller 14, or depending on the required rotation direction of the sheet 5, the second drive roller 14 is rotated at a lower speed than the first drive roller 12. In order to be able to selectively rotate the first drive roller 12 and the second drive roller 14 synchronously or asynchronously, the first motor 16 and the second motor 17 are adjusted and drive-controlled with respect to each other by a control device.

[0012] A control device not shown in the drawings acquires information regarding the position of the sheet 5 from a pair of optical sensors 19 or a line sensor 20, and drives and controls both motors 16 and 17 based on these signals. In a certain printing job, as shown in FIG. 1b, when the sheet 5 is conveyed with its longer sheet edge forward in the landscape mode, the signal of the sensor 19 is used. The sensor 19 is a reflection light switch. In another printing job, when the sheet 5 is conveyed with its shorter sheet edge forward in the portrait mode, the signal of the line sensor 20 is used. Therefore, in both modes, it is guaranteed that the position adjustment of the sheet 5 is performed based on the longer sheet edge, which is important for the subsequent processing of the sheet 5.

[0013] The first drive roller 12 and the second drive roller 14 are rotatably supported on the carriage 21 so as to be coaxially aligned with each other. The carriage 21, together with the two drive rollers 12 and 14, is supported so as to be position-adjustable in a direction transverse to and in the reverse direction of the conveyance direction 6. The position adjustment movement 22 of the carriage 21 is shown by a bidirectional arrow in FIG. 1b and is used to laterally position-adjust the sheet 5. The drive device 23 that drives the position adjustment movement 22 of the carriage 21 is symbolically shown in FIG. 1b, which is highly schematic, and will be described in more detail later with respect to FIG. 6.

[0014] The first opposing pressure roller 13 and the second opposing pressure roller 15 are rotatably supported within the support 24 and can be brought into contact with the first and second drive rollers 12, 14 by the stroke motion 25 of the support 24, and can be separated from the first and second drive rollers 12, 14 again. As will be described in detail later with reference to FIG. 7, since the support 24 is rotatably supported, the stroke motion 25 is a turning motion. The periodic stroke motion 25 performed in the conveyance cycle of the sheet 5 is driven by a drive device (not shown in the drawings). This drive device may be a pneumatic working cylinder, a linear drive device, a solenoid, or a motor-driven cam transmission. The position adjustment device 1 is followed in the conveyance direction 6 by a sheet conveyance device 26 which is a component of the image forming section 4. The sheet conveyance device 26 comprises one or more conveyance rollers that cooperate with the conveyor belt or tablet chain of the image forming section 4. The conveyor belt or tablet chain supports the sheet 5 during printing, for example by inkjet, and circulates on an annular track.

[0015] Hereinafter, with reference to FIGS. 1a to 6b, the function of the position adjustment device 1 will be described. This position adjustment device 1 is shown in side view and plan view in each operating stage, similar to FIGS. 1a and 1b.

[0016] In the operating stage shown in FIGS. 1a and 1b, the first sheet 5 among the sheets 5 conveyed successively in the conveyance direction 6 has not yet reached the position adjustment device 1. The sheet 5 is illustrated by a dashed-dotted line in FIG. 1b. The sheets 5 are conveyed by the conveying device 9 at a small interval from each other.

[0017] In the operating stages shown in FIGS. 2a and 2b, the leading edge 28 of the first sheet 5 has already reached the position adjusting device 1. The sheet 5 is sandwiched between the drive rollers 12, 14 and the counter-pressure rollers 13, 15 of the position adjusting device 1. The carriage 21 is located at the central neutral position 27 with respect to its position adjusting movement 22. The motors 16, 17 are driven and controlled such that the first drive roller 12 rotates at the same speed as the second drive roller 14. The leading edge 28 of the sheet 5 has reached the left sensor 19 or the target area of the sensor 19 in the conveying direction 6, activating this sensor 19. This is indicated by a cross in the drawing. At this point, the leading edge 28 has not yet reached the right sensor 19 in the conveying direction 6.

[0018] In the subsequent operating stages shown in FIGS. 3a and 3b, the leading edge 28 reaches the right sensor 19 in the conveying direction 6, activating this sensor 19. Both sensors 19 are located on a virtual line perpendicular to the conveying direction 6. From the time difference between the activation of the left sensor 19 (FIG. 2b) and the activation of the right sensor 19, the control device connected to the sensors 19 can calculate the inclination position of the sheet 5 taking into account the known spacing between the sensors 19 relative to each other.

[0019] FIGS. 4a and 4b show an operating stage in which the sheet 5 is positionally adjusted both orthogonally and laterally relative to the conveying direction 6. To positionally adjust the leading edge 28 perpendicular to the conveying direction 6, the second drive roller 14 rotates faster than the first drive roller 12. As a result, the sheet 5 is rotated about a vertical axis perpendicular to the plane of the drawing in FIG. 4b, and in this embodiment, this rotation is performed counterclockwise. For this purpose, the control device drives and controls the first motor 16 and the second motor 17 with the required speed difference depending on the calculated inclination angle.

[0020] At the same time, the line sensor 20 detects the position of the side edge portion 29 of the sheet 5 and notifies the control device of the measurement result. In response to the signal from the line sensor 20, the control device drives and controls the drive device 23, whereby the drive device moves the carriage 21 in the first direction 30. Together with the carriage, the first roller pair 10, the second roller pair 11, and the sheet 5 sandwiched between both roller pairs 10, 11 are moved in the first direction 30 until the line sensor 20 notifies the control device that the side edge portion 29 has reached the required target position 31 (see FIG. 5b).

[0021] Figures 5a and 5b show the operating stage in which the first sheet 5 has achieved the position adjustment necessary for printing the sheet 5 within the image forming section 4. The leading edge 28 is position-adjusted to be orthogonal to the conveying direction 6, and the side edge 29 is located at the lateral target position 31. At this point, the sheet 5 is still positioned between the driving rollers 12, 14 and the opposing pressure rollers 13, 15, and the section behind the sheet 5 is still sandwiched between both roller pairs 10, 11. Now, the control device drives and controls the driving device (not shown) of the support 24, so the support 24 performs an upward movement 34. Due to this upward movement 34, the first opposing pressure roller 13 and the second opposing pressure roller 15 are lifted from the sheet 5. By lifting the opposing pressure rollers 13, 15, the clamping of the sheet 5 is released, and the sheet 5 is released from the position adjustment device 1 and is already captured by the sheet conveying device 26 at this time. After the sheet 5 is sandwiched between at least one conveying roller of the sheet conveying device 26 and a conveyor belt (or alternatively a tablet chain) at its leading edge, the trailing edge of the sheet 5 is indeed still positioned between the driving rollers 12, 14 and the opposing pressure rollers 13, 15, but the trailing edge is not clamped. Subsequently, the control device activates the driving device 23, whereby the driving device runs the carriage 21 back to the neutral position 27 in the second direction 32. This occurs during the "loose" overlap of the sheet 5 between the driving rollers 12, 14 of the position adjustment device 1 and the opposing pressure rollers 13, 15, as can be confirmed from Figure 5b. The fact that the carriage 21 moves back to the central neutral position 27 together with the driving rollers 12, 14 is already carried out at a stage where the section behind the sheet 5 is still in an opposing position with the position adjustment device 1 or its roller pair 10, 11, which can minimize the interval 33 between consecutive sheets 5. Thereby, advantageously, a high sheet conveying cycle is achieved. The first motor 16 and the second motor 17 already rotate at the same rotational speed again in the operating situations shown in Figures 5a and 5b, that is, they rotate synchronously with each other.

[0022] Figures 6a and 6b illustrate the operating stage in which the position adjusting device 1 is prepared for the next position adjusting cycle. The carriage 21 is located at the central neutral position 27, and the drive rollers 12, 14 attached to the carriage 21 are also located at the neutral position. At the corresponding intermediate position, the support 24 provided with the opposing pressure rollers 13, 15 is also located. The centering device used to return the support 24 to the intermediate position will be described in more detail later with reference to FIGS. 7 to 9c.

[0023] The drive device for rotating the support 24 is drive-controlled such that the support 24 performs the mounting movement 35. As a result of this mounting movement, the opposing pressure rollers 13, 15 are preferably mounted on the drive rollers 12, 14 within the gap between the already position-adjusted sheet 5 and the sheet 5 to be position-adjusted next. This mounting movement 35, together with the upward movement 34 in the reverse direction, forms the stroke movement 25. When the opposing pressure rollers 13, 15 are mounted on the drive rollers 12, 14 within the sheet cavity and the leading edge of the sheet 5 to be position-adjusted next enters the roller pair 10, 11, the sheet 5 to be position-adjusted next is smoothly clamped. The motors 16, 17 and thus the drive rollers 12, 14 rotate at the same rotational speed.

[0024] The successive position adjustment of the next sheet 5 is performed in the same manner as already described based on the first sheet 5.

[0025] FIG. 7 shows a cross-sectional view of the position adjusting device 1 as seen from a perspective corresponding to the conveying direction 6. Here, the drive device 23 for driving the position adjusting movement 22 for laterally adjusting the sheet 5 is shown in more detail. The drive device 23 is a linear motor having a primary part 36 and a secondary part 37. The primary part 36, which can also be called the stator, is arranged on the stationary frame 38 and is formed as a base having windings. The secondary part 37, which can also be called the rotor, is arranged on the carriage 21 and is configured as a permanent magnet in the form of a magnetic plate.

[0026] As can be seen from FIG. 1b, the motors 16, 17 of the drive device 1 are each coupled to the drive rollers 12, 14 via one shaft 39, 40. A first shaft-hub coupling 41 that couples the shaft 39 to the first drive roller 12 so as to transmit torque and is axially movable, and a second shaft-hub coupling 42 that couples the shaft 40 to the second drive roller 14 so as to transmit torque and is axially movable are shown in FIG. 7.

[0027] Since the structures of both shaft-hub couplings 41, 42 arranged symmetrically with respect to the mirror plane are equal, this structure applied to both shaft-hub couplings 41, 42 will be described below in the example of the first shaft-hub coupling 41. A bush 45 is rotatably supported on a side wall 43 of the carriage 21 that protrudes downward via one or a plurality of rolling bearings 44 (as shown in the figure). The shaft 40 is axially movably supported within the bush 45 via a linear guide 46. Therefore, the bush 45, which is supported immovably axially within the carriage 21, can move relative to the shaft 40 and the motor 17 together with the carriage 21 during the position adjustment movement 22 of the carriage 21. Since the drive roller 12 is fixed immovably axially on the bush 45, the linear guide 46 enables the movement of the drive roller 12 in the direction of the geometric axis of rotation 47 relative to the shaft 40 and the motor 17. The linear guide 46 is shown in FIG. 7 in a significantly simplified manner and will be described in more detail later with respect to FIGS. 10 and 11.

[0028] FIG. 7 further shows that the support 24 has a shaft portion 48, and the opposing pressure rollers 13, 15 are rotatably mounted on the shaft portion 48. For the sake of simplicity of the drawing, it is not shown that the opposing pressure rollers 13, 15 are fixed so as not to slide axially on the shaft portion 48. The support 24 is provided with a first centering surface 49 and a second centering surface 50, and these centering surfaces 49, 50 are formed in a wedge 51 attached to the shaft portion 48. The wedge 51 is disposed between a third centering surface 52 and a fourth centering surface 53, and the third centering surface 52 and the fourth centering surface 53 are formed in small rollers 54, 55. The small rollers 54, 55 are separately fixed and rotatably supported on, for example, a machine frame, separately from the support 24. Instead of the small rollers 54, 55, non-rotatable pins may be provided, and in this case, higher wear of the centering surfaces 49, 50, 52, 53 than when the small rollers 54, 55 are used can be expected. The central axes of the small rollers 54, 55 are oriented parallel to each other and perpendicular to the shaft portion 48. The centering surfaces 49, 50, 52, 53 together form a centering device 56 for centering the support 24 provided with the opposing pressure rollers 13, 15 at an intermediate position 57. This intermediate position 57 is aligned with the central neutral position 27 of the carriage 21 provided with the drive rollers 12, 14, as shown in FIG. 7.

[0029] In FIG. 8, the support 24 is shown alone together with a support portion not shown in FIG. 7. The shaft portion 48 is coupled to a shaft 60 via a first arm 58 at one end thereof and via a second arm 59 at the other end thereof. Through the first arm 58 and the second arm 59, a stroke motion 25 (FIG. 1a) is transmitted from the shaft 60 to the shaft portion 48, and in this case, the shaft portion 48 is pivoted about the rotational axis 61 of the shaft 60. The shaft 60 is rotatably supported in the machine frame via rotational bearings 67, 68 symbolically suggested in the drawing, and is driven such that the shaft 60 performs a rotational reciprocating motion 62 about the rotational axis 61 in the conveying cycle of the sheet 5.

[0030] The first arm 58 has a first joint 63 and a second joint 64, and the second arm 59 has a third joint 65 and a fourth joint 66. The joints 63, 64, 65, 66 are flexure joints 63, 64, 65, 66, and realize the lateral movement 69 of the support 24 provided with the opposing compression rollers 13, 15. To form the flexure joints 63, 64, 65, 66, both arms 58, 59 are defined and weakened at these locations. The lateral movement 69 is performed asynchronously and in parallel with the position adjustment movement 22 when the sheet 5 is laterally position-adjusted (Fig. 1b). The rotary bearings 67, 68 enable the vertical position adjustment of the support 24, that is, enable the vertical component of the turning movement performed by the support 24 around the rotary bearings 67, 68. The flexure joints 63, 64, 65, 66 enable the horizontal position adjustment of the support 24, that is, the lateral movement 69. In this case, the arms 58, 59 are elastically deformed within the flexure joints 63, 64, 65, 66.

[0031] Figs. 9a to 9c show the successive steps when the support 24 is position-adjusted by the centering device 56.

[0032] Figure 9a shows the first stage, in which the carriage 21 equipped with the drive rollers 12, 14 is located at the central neutral position 27, and the support 24 equipped with the opposing pressure rollers 13, 15 is located at the intermediate position 57. As a result, the first drive roller 12 and the first opposing pressure roller 13 are located on one line, and the second drive roller 14 and the second opposing pressure roller 15 are also located on one line. The opposing pressure rollers 13, 15 are pressed against the drive rollers 12, 14, whereby the sheet 5 is sandwiched between the rotating drive rollers 12, 14 and the rotating opposing pressure rollers 13, 15. The clamping force 70 of the rollers 12, 13, 14, 15 is symbolically shown by arrows in the figure. In the first stage described in this specification, the wedge 51 is located exactly in the center between the small rollers 54, 55, but there is no contact between the first centering surface 49 and the third centering surface 52, and there is also no contact between the second centering surface 50 and the fourth centering surface 53.

[0033] Figure 9b shows the second stage of the position adjustment process. In this stage, the carriage 21 equipped with the drive rollers 12, 14 moves towards the right as viewed in the conveying direction 6. The position adjustment movement 22 in the first direction 30 required for this is driven by a linear motor (drive device 23). In this case, the sheet 5 is moved based on the friction between the drive rollers 12, 14 and the sheet 5, and the support 24 having the opposing pressure rollers 13, 15 is moved based on the friction between the sheet 5 and the opposing pressure rollers 13, 15. Therefore, the support 24 performs a lateral movement 69 towards the right. The position of the wedge 51 changes relative to the small rollers 54, 55, but the wedge 51 does not contact the small rollers 54, 55. The lateral movement 69 is performed until the control device that drives and controls the drive device 23 of the carriage 21 is notified by the line sensor 20 (Figure 1b) that the side edge 29 of the sheet 5 has reached its target position 31 (Figure 5b). The centering surfaces 50, 53 are arranged so that the contact between these centering surfaces 50, 53 is excluded even in the further lateral movement 69 where the contact is maximum.

[0034] Figure 9c shows the third stage, in which after the lateral position adjustment of the sheet 5, the carriage 21 and the support 24 are returned again. In this case, the support 24 is moved upward by the upward movement 34, and at this time the opposing pressure rollers 13, 15 are lifted from the sheet 5. Based on the upward movement 34, the second centering surface 50 contacts the fourth centering surface 53, so through this propulsion wedge action, the support 24 is pushed back to its intermediate position 57 toward the left, and the support 24 provided with the opposing pressure rollers 13, 15 performs a lateral movement 69 toward the left. When the support 24 reaches the intermediate position 57, the first centering surface 49 abuts against the third centering surface 52, and the second centering surface 50 abuts against the fourth centering surface 53, that is, the support 24 is centered.

[0035] The drive device 23 of the carriage 21 drives the position adjustment movement 22 of the carriage 21 in the second direction 32 until the carriage 21 reaches the central neutral position 27 in the third stage. This is done at least partially during the period when the sheet 5 is still loosely placed without the clamping force 70 being applied, between the rotating drive rollers 12, 14 and the lifted opposing pressure rollers 13, 15.

[0036] Thereafter, the cycle ends, and the next cycle for laterally position - adjusting the next sheet 5 starts with the lowering of the support 24. In this case, the support 24 performs the mounting movement 35 (Figure 6a), and the next sheet 5 is sandwiched between the drive rollers 12, 14 and the opposing pressure rollers 13, 15. By the mounting movement 35, the support 24 reaches from the position shown in Figure 9c to the position shown in Figure 9a.

[0037] In FIGS. 10 and 11, the shaft-hub coupling portion 41, which was shown in FIG. 7 in a significantly simplified manner, is shown in detail. FIG. 10 is a view having the line-of-sight direction X shown in FIG. 11, and FIG. 11 is a view along the cutting line XI-XI shown in FIG. 10. It can be confirmed that the clamping bush 71 is mounted within the bush 45. The clamping bush 71 is referred to as being arranged within its spring 72 in order to clamp the linear guide 46. The linear guides 46 are arranged equidistantly about the axis of rotation 47. Thus, in the illustrated example with three linear guides 46, one of the linear guides 46 is arranged every 120°. Each linear guide 46 consists of a running rail 73 located radially inward, that is, with respect to the axis of rotation 47, a running rail 74 located outward, and rolling elements 75 arranged between these running rails 73, 74. The rolling elements 75 run on the running rails 73, 74 during the position adjustment of the carriage 21. A retainer for holding the rolling elements 75 at a pre-defined distance from each other is not shown in detail in the drawing. The rolling elements 75 are formed as balls, and the linear guides 46 are sometimes particularly referred to as ball cage rail guides.

[0038] The springs 72 are each arranged within the hollow chamber 76 of the clamping bush 71 and are each supported while applying a preload to the radially inner wall and the radially outer wall of the hollow chamber 76. The outer running rail 74 is inserted into the inner wall of the hollow chamber 76, and the inner running rail 73 is inserted into the shaft 39. By the pressing of the spring 72 against the inner wall, the flexure joint 77 deforms elastically, and the flexure joints 77 each form a pair to support the inner wall. Thereby, the inner wall of the hollow chamber 76 deflects radially inward, and the inner diameter of the clamping bush 71 is elastically reduced. Thus, the unit consisting of the outer running rail 74, the rolling elements 75, and the inner running rail 73 respectively is compressed and preloaded.

[0039] In this example, a strip-shaped or belt-shaped corrugated spring is used as the spring 72. This spring extends linearly, unlike a typical corrugated spring which extends in a loop. The spring 72 is made of a thin spring steel plate. When the spring 72 is tightened, the "size" of the corrugated portion of this spring 72 is reduced.

[0040] The shaft 39 and the linear guide 46 inserted into the shaft 39 form a spline 76 that transmits torque together. In this case, the linear guide 46 forms the teeth of the spline 76. The torque transmitted from the first motor 16 to the linear guide 46 via the shaft 39 is transmitted from the linear guide 46 to the clamping bush 71, and then to the bush 45. The bush 45 is fixed on the clamping bush 71 and is rotatably supported in the carriage 21 via one or more rolling bearings 44. The clamping bush 71 can be called the first bush 71, and the bush 45 can be called the second bush 45.

Explanation of Signs

[0041] 1 Position adjusting device 2 Feeder 3 Machine 4 Image forming section 5 Sheet 6 Conveying direction 7 Guide plate 8 Conveying gap 9 Conveying device 10 First roller pair 11 Second roller pair 12 First driving roller 13 First counter pressure roller 14 Second driving roller 15 Second counter pressure roller 16 First motor 17 Second motor 18 Sheet conveying plane 19 Sensor 20 Line sensor 21 Carriage 22 Position adjusting movement 23 Driving device 24 Support 25 Stroke motion 26 Sheet conveying device 27 Neutral position 28 Front edge 29 Side edge 30 First direction 31 Target position 32 Second direction 33 Interval 34 Ascending motion 35 Mounting motion 36 Primary part 37 Secondary part 38 Frame 39 Shaft 40 Shaft 41 First shaft - hub coupling part 42 Second shaft - hub coupling part 43 Side wall 44 Rolling bearing 45 Second bush 46 Linear guide 47 Axis of rotation 48 Shaft part 49 First centering surface 50 Second centering surface 51 Wedge 52 Third centering surface 53 Fourth centering surface 54 Small roller 55 Small roller 56 Centering device 57 Intermediate position 58 First arm 59 Second arm 60 Shaft 61 Axis of rotation 62 Reciprocating motion 63 First flexure joint 64 Second flexure joint 65 Third flexure joint 66 Fourth flexure joint 67 Rotation bearing 68 Rotation bearing 69 Lateral motion 70 Clamping force 71 Clamping bush (first bush) 72 Spring 73 Inner running rail 74 Outer running rail 75 Rolling element 76 Hollow chamber 77 Flexible joint

Claims

1. 1. A method for aligning a sheet (5) in a feeder (2) of a machine (3) for processing sheets, comprising conveying the sheet (5) in a conveying direction (6) by a first drive roller (12) and a first counter-pressure roller (13) cooperating with the first drive roller (12) and by a second drive roller (14) and a second counter-pressure roller (15) cooperating with the second drive roller (14) to a sheet conveying device (26) and laterally aligning the sheet (5), In a first step, the sheet (5) is clamped between the first drive roller (12) and the first counter pressure roller (13) and between the second drive roller (14) and the second counter pressure roller (15), and a carriage (21) on which the first drive roller (12) and the second drive roller (14) are supported is caused to travel together with the clamped sheet (5) in a first direction (30) transverse to the conveying direction (6), thereby laterally adjusting the position of the sheet (5); in a second step, after the sheet (5) has been captured by the sheet transport device (26) and before the carriage (21) with the first drive roller (12) and the second drive roller (14) is caused to travel back in a second direction (32) opposite to the first direction (30), the first counter pressure roller (13) is lifted from the sheet (5) on the first drive roller (12) and the second counter pressure roller is lifted from the same sheet (5) on the second drive roller (14); In a third step, a return run of the carriage (21) in the second direction (32) is already performed while the sheet (5) which is no longer clamped is still located in the area between the first drive roller (12) and the first counter pressure roller (13) and in the area between the second drive roller (14) and the second counter pressure roller (15). A method comprising:

2. 2. The method according to claim 1, characterized in that the first drive roller (12) is driven in rotation by a first motor (16) and simultaneously the second drive roller (14) is driven in rotation by a second motor (17).

3. 3. The method according to claim 2, characterized in that, in order to perform a skew position correction of the sheet (5), the first drive roller (12) is driven by the first motor (16) at a speed different from the speed at which the second drive roller (14) is driven by the second motor (17).

4. 4. The method according to claim 2 or 3, characterized in that the carriage (21) is moved relative to the first motor (16) when moving in the first direction (30) and relative to the second motor (17) when moving in the second direction (32).

5. 5. The method according to claim 4, characterized in that the carriage (21) is moved in the first direction (30) and in the second direction (32) by a drive (23) configured as an electromagnetic linear motor.

Images