Vehicle and structure shield with improved hard points

The invention relates to a device for feeding sheets which separates sheets of paper or card from a stack and feeds them one by one from the device in a direction parallel to the plane of the sheets. The sheet feeder can be part of a paper processing machine, e.g. creasing, perforating or cutting between a pair of rollers, or simply delivering single sheets to a separate device for further processing. The nature of subsequent operations is not the subject of the present invention.

[0002] The sheets fed through the feeder can be made of paper or cardboard, e.g. in a density range of 50 g / m2.² up to 500 g / m²or from similar material like thin plastics. For simplicity, and without restrictions, the material will be referred to as "paper" below.

BACKGROUND OF THE INVENTION [0003] Paper feeders are known in which conveyor means are used, such as a belt or roll for drawing a single sheet from the bottom of a stack of sheets that rests on a feeder platform. Separating the bottom sheet from the stack is difficult due to the friction exerted by the next sheet in the stack from above and the fixed parts of the feeder platform from below. In order for the sheet to be ejected from the stack, the clamping force between the sheet and drive elements must be higher than these friction forces. This occurs both when the bottom sheet is loaded through the entire stack, and only on several sheets.

[0004] The friction between the movable sheet and the stationary parts of the feeder platform results in seizures on the surface of the paper. This is a particular problem due to the increasing use of digital printing on a smooth surface.

[0005] In some sheet feeders, suction drums are used to increase the nip between drive elements and paper. The surface of such a drum is perforated, and the air pump sucks air from the inside of the drum so that the paper adheres to its surface. The air pump can also direct the air flow to the stack edge so as to assist in separating the sheets from the stack. However, air pumps increase the weight and complexity of the sheet feeder as well as the cost of its operation and noise levels.

[0006] The sheet feeder should allow the sheets to be delivered as quickly as possible up to the maximum working speed of any device for further processing. It should be able to provide only one sheet at a time, since a feed error consisting of two sheets can, at best, disrupt further processes and, in the worst case, cause a deadlock, resulting in a costly delay in the production process. U.S. Patent No. 3,664,660 discloses a sheet feeder according to the preamble of claim 1.

Summary of the invention [0007] A first object of the invention is a sheet feeder comprising:

Feeder platform for stacking sheets for feeding; feeder block; a drive belt for frictionally retaining the bottom of the bottom sheet in the stack and forcing it to move in the feed direction below the feeder block; a feed block consisting of a friction shoe protruding from the bottom of the feeder block towards the drive belt so as to define a gate between it and the first face just above the gate, the first face defining a plane inclined at a first angle to the feeding direction, and the friction shoe does not intersect the face of the first face.

[0008] The sheet feeder according to the invention is characterized by feeding single sheets quickly and reliably over a wide range of paper thicknesses and stack heights. It works quietly because it does not use an air pump, and reduces the surface scratches of the sheets.

[0009] The first angle may be less than 45 ⁰, and preferably have a value of from 25 ⁰ up to 30 ⁰.

[0010] The feed block may also comprise a second end face above the first face, the second face being inclined to the feeding direction at a second angle that is greater than the first angle.

[0011] The feed block may further comprise a bottom surface that is below the first face and faces the drive belt, the friction shoe protruding from the bottom of the feeder block below the lower surface. Preferably, the bottom surface of the feeder block defines a plane that is substantially parallel to the feeding direction. The feed block further comprises a curved surface that provides a smooth transition from the first face to the bottom face. A suitable material for the feeder block is aluminum or aluminum alloy; and at least the first face of the feeder block may be anodized.

[0012] The friction shoe preferably has a bottom surface of the block that is substantially parallel to the feeding direction. It may further comprise a front face of a block that adheres to the upper end of the bottom surface of the block, wherein the front face of the block is inclined at an angle smaller than 45.⁰ to the direction of feeding, where it adheres to the bottom surface of the block.

[0013] In a preferred embodiment of the sheet feeder according to the invention, a pair of drive belts is disposed on opposite sides of the feeder axis, and the pair of feeder blocks is aligned with the respective drive belts.

[0014] A pair of feeder blocks may be mounted on one support, which in turn is mounted on the sheet feeder frame. The structure may include means for adjusting the height of at least one of the feeder blocks relative to the bracket or adjusting the height of the bracket relative to the frame.

[0015] Another object of the invention is a sheet feeder, which consists of: a feeder platform for supporting a stack of sheets to be fed; feeder block; and drive means that frictionally hold the bottom sheet in the stack and cause the sheet to move in the feed direction at the first speed through a gate defined between the feeder block and the drive means; the sheet feeder further comprises a pair of counter-rotating pre-gate acceleration rollers for clamping the sheet and pushing it out of the gate with a second speed that is higher than the first speed. The second speed may be at least twice as high as the first speed and is preferably about five times higher than the first speed.

[0016] The increase in the speed at which the sheets are transported causes the gates to open between successive sheets, which improves handling thereof behind the sheet feeder.

[0017] A third object of the invention is a sheet feeder comprising: a feed platform platform for holding a stack of sheets to be fed; feeder block; drive means that frictionally hold the bottom sheet in the stack and cause the sheet to move in the feeding direction through a gate defined between the feed block and the drive means; wherein the feeder platform is inclined to the horizontal and includes a set of feed rollers, each of which can rotate freely about a substantially horizontal axis.

[0018] Due to the possibility of the sheets moving on the freely rotating rolls in the areas where they do not contact the drive elements, the sheet feed is more confident and reduces the scratching of the surfaces.

The sheet feeder may further comprise at least one guide plate arranged in a vertical and transverse plane with respect to the set of rollers. The roller unit determines the plane of the feeder platform, which is tangent to the tops of the rollers. The lower edge of the guide plate passes below the plane between adjacent roller pairs.

[0020] A further object of the invention is a sheet feeder comprising: a feed platform to keep a stack of sheets to be fed; feeder block; drive means that frictionally hold the bottom sheet in the stack and cause the sheet to move in the feeding direction through the gate defined between the feeder block and the drive elements, the drive elements being part of the detachably mounted assembly in the feeder platform. This enables easy and quick replacement of worn parts of drive elements, such as belts or rollers.

[0021] Preferably, the drive element assembly comprises means at one end of the assembly for axially assembling the assembly in the feeder platform, and at the other end of the assembly - means for attaching the assembly to the feeder platform. Axially mounted elements may include jaws on the drive assembly to hold the bar on the feeder platform or vice versa. The drive assembly may also include a first gear to engage with a second gear below the feeder platform, which supplies power to the drive means.

Drawings [0022] Figure 1 is a side view of a paper creasing machine which houses a sheet feeder according to the invention.

Figure 2 is a plan view of part of the apparatus shown in Figure 1. Figures 3, 4 and 5 are a top view, a side view and a front view, respectively, of the drive assembly and the device feed block shown in Figure 1. Figure 6 schematically shows a side guide of the device shown in Figure 1.

Figures 7, 8 and 9 respectively show a side view, a top view and a front view of a feeder block and a mounting bracket of the apparatus shown in Fig. 1.

Figures 10 and 11 show side views of the feeder block and friction block respectively of the device shown in Fig. 1 with the preferred dimensions indicated.

Detailed Description [0023] Figure 1 shows a device 2 for creasing, perforating or cutting paper sheets from a stack. The stack of paper to be machined (not shown) is placed on the feeder platform 4 supported by the side guides 6. The sheet feeder according to the invention takes individual sheets of paper from the bottom of the stack and delivers them to the body 8 of the device 2 along the platform plane of the feeder 4. machining processes such as creasing, perforating or cutting in the device 2, the sheets are collected as the output stack in the output container 10. Alternatively, the treated sheets can be individually fed on rolls to other devices for further operations.

[0024] The control panel 12 allows the operator to control operating parameters of the device 2, such as speed, in the usual manner. The emergency switch 14 is located in a distinguished and easily accessible place.

[0025] Figure 2 shows a top view of the sheet feeder of the creasing machine 2, showing the creasing machine 20, but without the output container 10. The feeder block (described below) that determines the sheet feed gate 26 is also omitted to show the details of the drive assembly 40. The stack of paper (not shown in Fig. 2) rests on the platform of the feeder 4, above the drive unit 40, which acts on the lowest sheet in the stack so as to feed it into the machine in the direction indicated by arrow 24. The drive mechanism of the sheet feeder will be explained in detail. below. In FIG. 2, it can be seen that the drive assembly 40 includes a pair of drive belts 42 whose upper surfaces lie substantially in the plane of the feeder platform 4.

Most of the platform surfaces of the feeder 4 are formed by the feed roller assemblies 22. The feed roller assemblies 22 are on either side of the drive assembly 40 for supporting the paper surface in the stack so as not to fall on the drive assembly. Each of the rollers 22 is mounted such that it can rotate freely about the axis with minimal resistance. The axes of the rollers 22 are substantially horizontal and perpendicular to the direction of movement of the sheets. Since the platform plane of the feeder 4 is deviated from the level, as shown in Fig. 1, the stack of paper placed on the platform of the feeder 4 will slide along the platform incline towards the sheet pickup gate 26.

[0027] It is possible to form the upper part of the platform of the feeder 4 as a removable extension 28, which at the user's request can be used so that it is possible to stack a stack of larger sheets. To limit the space occupied by the device 2, the extension can be retracted. The removable extension 28 includes further roller assemblies 22. Most of the feeder platform 4 surfaces are feed rollers 22. If there is a friction between the sheet and the roll, the freely rotating roll can simply rotate behind the movement of the sheet, avoiding scratches. sheet surface.

The sides of the stack on the grate of the feeder 4 are supported by a pair of side guides 6. The side guides 6 are essentially vertical plates arranged in a plane parallel to the feeding direction 24. The guides 6 can be moved transversely to the feeding direction along the transverse bars 30 (in Figure 2 only one is visible) to match the stacks of sheets with different widths. To release the guides 6 so that they can slide over the rods 30 and then lock them in a predetermined position, ordinary means can be used. Although in FIG. 2 both side guides 6 are maximally spaced in the same direction, during normal operation, both guides 6 may be at the same distance on opposite sides of the sheet feeder axis, that the sheets can be fed centrally to the drive assembly 40 and transported through the device without any deflection forces. To make it easier for the operator to set the guides 6, the indicator 32 is used, calibrated in appropriate units of distance from the axis. A known balancing mechanism (not shown) for aligning the guides symmetrically with respect to the axis may also be used.

[0029] Conventional side guides are often of L-shaped cross-section such that the edges of the bottom sheet in the stack rest on the horizontal portions of the inwardly oriented guides. The apparatus according to the invention preferably uses side guides 6 that do not have a horizontal part, which allows maximum contact of the bottom of the stack with the feed rollers 22. Figure 6 schematically shows the relationship between the bottom of the side guides 6 and the set of rollers 22. The guide rail mounting mechanism is not considered 6 or rolls. The rollers 22 in the assembly define a plane 34 that is tangential to the tips of the rollers. In this plane, the bottom sheet of the stack is supported. The lower edge of the lateral guide 6 comprises a series of notches 36 and frets 38, alternately. Each cut 36 preferably has the shape of a circular arc, which is coaxial with the axis of the respective roll 22 so as to provide a sufficient distance around the free rotation of the roll. Each threshold 38 may have an acute or blunt tip, provided that the point of the sill extends beyond the plane 34 between a pair of adjacent rolls.

[0030] Accordingly, the threshold assembly 38 allows the stack to be guided down to the bottom sheet of paper that rests in the plane 34. If the bottom edge of the side guide 6 were straight, it would have to be positioned above the plane 34 at a height sufficient to cover the tops of the rolls, so that at least the bottom sheet in the stack would have sufficient space to slide sideways under the guide 6. The cutouts do not necessarily have to be made by cutting; any useful process can be used, such as stamping or forming. The shape of the lower edge of the lateral guide 6 does not have to be as shown in the figures. It is essential that the guides 22 do not interfere with their rotation above the rollers 22, and between the adjacent pairs of rollers it passes below the plane 34.

[0031] Turning back to figure 2, it is also possible to see a pair of accelerator rolls 46 that are positioned one above the other and below the sheet feeder gate 26. A sheet of paper pulled through the gate 26 by means of drive belts 42 is fed between counter-rotating rollers which clamp the sheet and move it out of the gate 26 at increased speed.

[0032] Accelerator rollers 46 move a sheet of paper into a creasing machine 20 where it is fed between a pair of counter-rotating rollers 48, one of which is shown in Figure 2. Drums 50 are mounted on rollers 48 whose friction surfaces clamp the sheet and pull it into a creasing machine. at the same speed at which he left the accelerator rolls 46. Rolling drums 48 are also mounted on shafts 48, which can be male and female, respectively, for creasing, perforating or cutting sheets in a known manner. The position of the drums 50, 52 on the respective shafts 48 can be varied to match the width of the sheets of paper and to the required arrangement of bends, perforations or cutouts. At the exit from the apparatus 20, the sheets are fed to the top of the output container 10 (figure 1),

The accelerator rollers 46 preferably move at high speed compared to the speed of the drive belts 42. For example, they can accelerate the paper sheets to a speed five times higher than the speed they give to the drive belts 42. The paper is basically continuously extracted from stack through the drive assembly 40 so that the front edge of one sheet follows the back edge of the previous sheet through the gate 26. Accelerating the sheets through the accelerator rolls 46 results in a gap between subsequent sheets, which is advantageous for further processing. For example, if instead of collecting sheets in the outlet container 10, they are delivered individually to the second device, it happens that it is necessary to feed them perpendicularly to the direction in which they leave the creasing machine.

[0034] Figures 3, 4 and 5 illustrate in more detail the removable drive unit 40 of the sheet feeder. The two drive belts 42 are placed at equal distances from the axle, on opposite sides. Each strip forms a continuous loop around the first and second drum 68, 70. A pair of first drums 68 is mounted on a common first shaft 69 below the feeder platform 4, above the gate 26. A pair of second drums 70 is mounted on a common second shaft 71 at a corresponding level, but slightly below the goal. The second shaft 71 has a gear 72 that is driven by a motor (not shown) and rotates both rollers 69, 71 and drives the belts 42. The rollers 69, 71 are rotated counterclockwise, as seen from Figure 4, so to drive the belts 42 along the feeder platform 4 towards and through the gate 26.

The drive unit 40 including the drive belts 42 is supported by a frame 54. The frame 54 has a latch 56 at one end and a fastening screw 58 at the other. Unscrewing the fastening screw 58 allows quick disconnection of the whole drive assembly 40 from the creasing machine 2 for example, for quick replacement of worn drive belts 42. The latch 56 includes a pair of adjustable jaws 57 that can respectively be seated and rotated on a pair of rods 59 forming part of the feeder platform structure 4. Alternatively, the rods 59 could be placed on a removable drive assembly 40 and the jaws 57 on the structure 60. The drive assembly can thus be detached from the grate of the feeder 4 by unscrewing one fastening screw 58, lifting the upper end of the assembly 40 so as to rotate the jaws 57 of the assembly around the rods 59,until the upper end is removed from the platform 4, and then pulling the assembly 40 along, essentially upwardly, so as to release the jaws 57 from the rods 59. The operation may be reversed to replace the drive assembly 40. When the drive assembly is in the up position assembly, the first gear 72 engages with a second gear (not shown) which is mounted below the feeder platform 4 and transfers the rotational power from the engine (not shown) to the drive assembly 40.which is mounted below the feeder platform 4 and transfers the rotational power from the engine (not shown) to the drive unit 40.which is mounted below the feeder platform 4 and transfers the rotational power from the engine (not shown) to the drive unit 40.

[0036] The picking of the paper sheets from the stack is controlled by a pair of feeder blocks 62 that are mounted by a bracket 64 on the sheet feeder frame such that each feeder block 62 is suspended above the respective drive belt 42. The friction block 66 projects from the bottom of each block dispenser 62 towards the respective drive belt 42, forming a gate 26 between them, which passes only one sheet at a time. The size of the gate 26 (i.e., the vertical spacing between the shoe 66 and the belt 42) can be adjusted manually by turning knobs 68 by rotating the screw connection between each of the feeder blocks 62 and the bracket 64, raising or lowering the feeder block 62. The spacing 26 is easiest to set to the value appropriate for the given thickness of paper to be processed, by sliding a sheet of paper between the friction shoe 66 and the drive belt 42, and then reducing the gap almost to stop the sheet. This ensures that no more than one sheet of paper will pass through the gate at once. The adjustment knobs 68 are easily accessible so that the size of the gate 26 can be tuned accurately during operation of the device.

[0037] An alternative configuration (not shown) is possible in which the vertical position of the bracket 64 is adjustable relative to the machine frame, preferably by means of a control knob similar to those shown. Preferably, at least one of the feeder blocks 62 should be adjustable relative to the support so that independent adjustment of both feeder blocks 62 is possible, for example if the drive belts 42 are worn at different speeds.

[0038] The face 70 of each feeder block 62 faces up towards the feeder platform 4. When the stack of sheets 65 is laid on the platform of the feeder 4, as schematically illustrated by the dots and bars in Figure 4, the stack slides over the feed rollers. 22 on the inclined surface of the feeder platform 4 until the front edges of the sheets in the stack 65 rest against the front face 70 of the feeder block 62. The face at least in part forms an acute angle with the plane of the feeder platform 4, which allows the bottom sheets in the stack to slide further from the upper sheets, and deforms at least the bottom portion of the stack 65 to the wedge shape. The next sheets in the stack are therefore slightly offset in relation to the other along the feed direction 24, which starts the process of their separation,⁰to the feeder platform, more preferably at an angle of 25⁰ up to 30⁰. The second, upper portion 73 of the end face, which gently passes into the lower portion 72, does not have to be inclined at such a sharp angle. The angle between the upper part 73 and the platform of the feeder 4 can be from 45⁰ up to 90⁰but a value between 60 is preferred⁰ and 70⁰.

[0039] The shapes of the feeder block 62 and friction block 66 are shown in detail in Figs. 7 to 9, and their particular dimensions in the solutions shown are indicated in Figures 10 and 11.

[0040] It is believed that the geometry close to the gate is the most important for obtaining a reliable sheet feeder, i.e. one that quickly and continuously feeds one sheet at a time through the gate without jamming. The bottom of the feeder block 62 is defined by the bottom surface 74, which is substantially parallel to the surface of the drive belt 42. The bottom surface 74 is fluidly connected to the lower side 72 of the end face 70 via the curved transition surface 76. As best seen in FIG. 9, the lower part Each delivery block 62 takes the shape of two side walls 78 with a recess 80 between them. The bottom surface 74 of each feeder block 62 therefore has a pair of concealed surfaces on the respective side walls 78. The friction shoe is mounted in a recess 80 between the side walls 78 so⁰) It should be noted that the shoe 66 does not intersect the plane 86 which is defined by the lower part 72 of the front face 70 of the feed block as indicated by the dashed line in fig. 7.

[0041] It is possible that the lower part 72 of the front face 70 of the feeder block is slightly curved, rather than completely straight, and thus does not define the actual plane over its entire length. In this case, said plane 86, which is not cut by the friction shoe 66, is tangential to the lowest part of the lower part 72, before it passes into the bottom surface 74 via the curved surface 76.

[0042] The friction shoe 66 is made of an elastic material such as rubber or a preferred polyurethane. It has been found that the polyurethane has a Shore A hardness of the order of 65, 80 or 90. Since the shoe 66 is rather flexible than completely stiff and the geometry of the gate is essential, it must be possible to securely mount the friction shoe 66 in the recess 80. 66 is fastened in two places to secure it against rotation.

At each point of attachment by the friction shoe 66, a horizontal hole passes with a metal (e.g. steel) sleeve 88 that has an internal thread. Through the openings in the opposite side walls 78 of the feeder block 62, four bolts 90 are passed, which are screwed into each end of each sleeve 88 to secure the friction shoe 66 against displacement.

[0043] The blocks of the feed 62 may be made of any rigid material, e.g. aluminum or aluminum alloy. Preferably, the surfaces of the feeder blocks 62 - and especially the end faces 70 that are in contact with the stack of paper - should be anodized so that their finish is smooth and durable.