WO2004078469A2

WO2004078469A2 - Device for forming creases in paper or cardboard

Info

Publication number: WO2004078469A2
Application number: PCT/GB2003/005625
Authority: WO
Inventors: Graham Harris
Original assignee: Graham Harris
Priority date: 2003-03-06
Filing date: 2003-12-22
Publication date: 2004-09-16
Also published as: GB2399056A; WO2004078469A3; AU2003295149A8; AU2003295149A1; GB0305076D0

Abstract

A device for creasing card comprises a rotary drum (2) and two wheels (4, 6) mounted adjacent to the drum (2), such that a sheet of card may be fed first between the drum (2) and one of the wheels (6) then between the drum (2) and the other of the wheels (4). A crease is formed in the card between a rib (22) on the drum (2) and a groove (16) in each of the wheels (4, 6) or between a groove in the drum (2) and a rib on each of the wheels (4, 6). The provision of two wheels (4, 6) helps to reduce cracking and improve the straightness of the crease. A resilient creasing strip (20) for a creasing device has a front surface along which is a creasing rib (22) and a rear surface along which is a locating rib (24) for locating the strip (20) in a pre-existing circumferential groove (12) in the drum (2) of the creasing device. The creasing strip (20) may further comprise a pad (26) at each end, by which the strip may be adhered to the drum (2) of the creasing device.

Description

TITLE

Cover creasing device

DESCRIPTION Technical field

The invention relates to devices for forming creases in paper or card. It has particular but not exclusive application to the cover feeder of a stitching machine, in which the cardboard cover of a booklet is creased to form a sharply defined spine before being folded around the contents of the booklet and stitched into place with staples.

The invention is relevant to the creasing of various weights and thicknesses of paper and card but is particularly suitable for heavier weights. The remainder of this specification uses the term "card" as an abbreviation for paper or card.

Background of the invention

In a conventional cover creaser, a steel drum of large diameter has a V-shaped groove around its circumference. A smaller, steel wheel has a creasing rib around its circumference. The drum and the wheel are adjacently mounted for rotation with their axes vertical so that a sheet of card lying in a vertical plane can be fed between the counter-rotating drum and wheel and will be creased between the rib of the wheel and the groove of the drum. Downstream from the creasing device, the card is folded along the crease around the contents of a booklet, whereby the crease forms a sharply defined spine. It has been found that the steel rib of the cover creaser tends to cause undesirable cracking along the crease when it is folded. Also, the rib and the groove hold the card between them at essentially a single point, which allows the crease sometimes to deviate from a straight line.

International patent application WO 00/55080 describes a creasing device, which is not a cover creaser but does avoiding cracking along the crease by using a resilient ring in place of a steel rib. The resilient ring may be readily replaced when it is worn or when the width or depth of the crease needs to be changed. It is not practical to apply a resilient ring to the drum of the known cover creaser because the drum is mounted on a shaft, which does not permit a ring to be passed over the end of the shaft and or the drum to be easily removed from the shaft.

The invention In a first aspect, the invention provides a device for creasing card, comprising a rotary drum and two wheels mounted adjacent to the drum, such that a sheet of card may be fed between an outer surface of the drum and an outer surface of one of the wheels then between the outer surface of the drum and an outer surface of the other of the wheels, to form a crease in the card between a rib on the drum and a groove in each of the wheels or between a groove in the drum and a rib on each of the wheels.

By feeding the card successively past two wheels, the crease is formed by the first wheel and reinforced by the second wheel. Thereby the definition of the crease is improved without increasing the pressure between the wheel and the drum, which would be likely to worsen the problem of cracking. In fact, using two wheels is found to substantially eliminate craclάng. Moreover, two wheels give two points of contact between the drum and the respective wheels. Thereby the card is effectively held on course-through-the-dev- ice-and-the-resulting- Grease-is-a-true-straight-line-defined- by the - two points of contact. In the case where the rib is on the drum and the grooves are in the wheels, then the provision of two wheels has a third advantage. Because the crease in this case is pushed outwards from the drum, the card tends to buckle away from the drum as it is fed around the circumference of the drum. The two wheels help to hold the card in contact with the surface of the drum.

In a preferred embodiment, the creasing device further comprises a frame on which the drum is rotatably supported, a first wheel support on which a first one of the wheels is rotatably supported and second wheel support on which a second one of the wheels is rotatably supported; wherein the first wheel support is secured to the frame such that the distance between the first wheel and the drum can be adjusted; and wherein the second wheel support is secured to the first wheel support such that the distance between the second wheel and the drum can be adjusted. It is important for reliable operation of the device that the correct pressure should be exerted on the card as it passes between the drum and the wheels. This is achieved by adjusting the distance between each wheel and the drum. In accordance with the invention, rather than adjusting each wheel independently, the second wheel may be adjusted relative to the first. Having correctly positioned the first wheel, it is much easier to make a fine adjustment to position the second wheel in relation to the first than to position the second wheel from scratch. This makes the device easy to set up and maintain without the services of a skilled engineer, which is an important consideration in everyday use by a printer.

Typically, the position of the first wheel support is adjusted by changing the angle of a strut that connects it to the frame. In one embodiment of the invention, the position of the second wheel support can be adjusted by similarly changing its angle relative to the first wheel support. However, in a preferred embodiment, the second wheel support can be adjusted by displacing it linearly relative to the first wheel support. For example, the second wheel support may be secured to the first wheel support with a dovetail joint to allow relative linear displacement parallel to the length of the joint. Linear adjustment generally allows simpler and more accurate adjustment mechanisms than angular adjustment.

Preferably, a screw thread is used for controlling the linear displacement to adjust the distance between the second wheel and the drum. In one example, the screw thread is non-rotatably fixed to the second wheel support and a nut on the screw thread engages the first wheel support in such a way that the nut cannot move along its axis, whereby rotation of the nut causes the screw thread to move along the axis of the nut, carrying with it the second wheel support. Clearly, the layout of the adjustment mechanism may be reversed so that the screw thread is fixed to the first wheel support. Alternatively, the screw thread may be fixed to the nut but rotatable in a threaded bore in the wheel mounting.

In a second aspect, the invention provides a resilient creasing strip having two ends, a front surface along which is a creasing rib and a rear surface along which is a locating rib for locating the strip in a circumferential groove in the drum of a creasing device. By using a strip with ends instead of an unbroken ring, the resilient creasing rib can be applied to the drum in situ and does not require removal of the drum from its shaft. As the drums of existing cover creasers already have a circumferential groove, the locating rib of the strip is a convenient means for ensuring that the resilient creasing rib is truly circumferential, i.e. that it lies in a plane perpendicular to the axis of the drum, and therefore will result in a straight crease.

The creasing strip may further comprise flanges extending laterally at each end of the strip to form a pad, by which the strip may be adhered to the drum of the creasing device. It is found sufficient to adhere the strip only at its ends and that around the circumference of the drum the strip is firmly held in the groove of the drum by its own tension. This facilitates set-up of the device and replacement of the strip.

The invention further provides a device for creasing card, comprising a rotary drum having a circumferential groove around its outer surface; a wheel having at least one circumferential groove around its outer surface; and a resilient creasing strip as previously defined, the locating rib of the strip being located in the groove of the drum; wherein the wheel is mounted adjacent to the drum, such that a sheet of card may be fed between the outer surface of the drum and the outer surface of the wheel, to form a crease in the card between the creasing rib of the creasing strip and the groove in the wheel.

Typically, the groove in the drum has a triangular cross-section and the locating rib of the creasing strip has a corresponding triangular cross-section.

The wheel may have a plurality of circumferential grooves of different widths in order to allow different widths of crease to be formed in a single creasing device. The drawings

Fig. 1 is a plan view of a cover creasing device in accordance with the invention. Fig. 2 is a partial, vertical section on the line A-A in Fig. 1.

Fig. 3 is a front view of a resilient strip for use in the cover creasing device of Fig. 1. Fig. 4 is a side view of the wheels and wheel mountings shown in Fig. 1. Fig. 5 is a sectional plan view on line B-B of Fig. 4.

Figs. 1 and 2 illustrate the relationship between a drum 2, a first wheel 4 and a second wheel 6 of a cover creasing device according to the invention. The drum 2 is conventional and has a central hole 8 for mounting on a vertical shaft (not shown) of a stitching machine in order for the drum 2 to be rotated by rotation of the shaft. As seen in Fig. 2, the drum 2 is not solid but to reduce its weight is generally I-shaped in vertical cross-section. The drum has a cylindrical outer surface 10 with a circumferential groove 12 of V-shaped cross-section, which is used in a conventional cover creaser to receive the card as it is creased under pressure from an adjacent steel wheel.

The first and second wheels 4,6 are the same as each other. Each wheel 4,6 has a smaller diameter and thickness than the drum 2. The wheel 4,6 has a cylindrical outer surface 14 in which are formed circumferential grooves 16 of rectangular cross- section and of differing widths. The wheels 4,6 are mounted so as to be freely rotatable about a vertical axis, with the outer surface 14 of each wheel close to the outer surface 10 of the drum 2 and one of the grooves 16 of each wheel aligned with the groove 12 of the drum 2.

Fig. 3 shows a generally flat strip 20 of a resilient material such as nitrile rubber. Extending along the length of the strip 20 and projecting from a front surface of the strip 20 is a creasing rib 22 of the resilient material, which has a generally rounded front edge, as seen in cross-section in Fig. 2. Extending along the length of the strip 20 and projecting from a rear surface of the strip 20 is a locating rib 24 of the resilient material. The locating rib 24 has a V-shaped cross-section to match the cross-section of the groove 12 in the drum 2, also as seen in Fig. 2. At each of its ends, the strip 20 is widened by laterally extending flanges to form a pad 26.

When setting up the creasing device, the resilient strip 20 is stretched around the drum 2 with the locating rib 24 of the strip 20 seated in the circumferential groove 12 of the drum. Adhesive is applied to the rear surface of the pad 26 at each end of the strip 20 and the pads 26 are stuck to the outer surface 10 of the drum. The tension of the strip 20 is sufficient to hold the locating rib 24 in the groove 12 without the need for adhesive along the length of the strip 20 between the pads 26. This facilitates removal of the strip 20 by peeling away just the pads 26 if the strip needs to be replaced because it is worn or a differently profiled strip is required.

Although shown shortened in Fig. 3, the strip 20 is long enough to extend exactly once around the circumference of the drum 2 so that the ends of the strip 30 meet and the creasing rib 22 forms a continuous circuit of the drum 2. The creasing rib 22 projects into one of the grooves 16 of the adjacent wheels 4,6, depending on the width of crease required. Optionally, different strips 20 having creasing ribs 24 of different widths can be provided to complement the different widths of groove 16 in the wheels 4,6.

The mounting of the wheels 4,6 is illustrated in Figs. 1, 4 and 5. A first wheel support 30 has an upper limb 31 and a lower limb 32. The first wheel 4 is mounted via a first axle 33 for free rotation on the underside of the lower limb 32 of the first wheel support 30. A strut 34 is accommodated in the gap between the upper and lower limbs 31,32 of the first wheel support 30 and is secured to the upper limb 31. The strut 34 is in turn secured to the frame (not shown) of the stitching machine.

The second wheel 6 is mounted via a second axle 36 for free rotation on the underside of a second wheel support 38. Means (not shown) may be provided for adjusting the vertical position of the wheels 4,6 so as to bring different ones of the grooves 16 into alignment with the creasing rib 22 on the drum 2. The first and second wheel supports 30,38 are connected to one another by a dovetail joint, seen in cross-section in Fig. 4. The dovetail joint 40 allows the second wheel support 38 to be linearly displaced relative to the first wheel support 30 along the length of the joint 40, as seen in Fig. 5 and indicated by the arrows 42 in Fig. 1. The dovetail joint 40 prevents the second wheel support 38 from moving upwards, downwards or away from the first wheel support 30.

The relative displacement of the first and second wheel supports 30,38 may be adjusted using adjustment means generally indicated at 44. The adjustment means 44 comprise a threaded pin 46, which is fixedly attached to the second wheel support 38 and extends from the support 38 in a direction parallel to the length of the dovetail joint 40. A nut 48 has an internally threaded bore, which engages the threaded pin 46, and a knurled outer rim 50. Part of the rim 50 of the nut is located between two shoulders 52 of the first wheel support 30. In the illustrated embodiment, the shoulders 52 are provided on a boss 54 that is fixedly screwed into the first wheel support 30 but alternatively the shoulders 52 could be integral with the first wheel support 30 or fixed to it in another manner. The shoulders 52 allow the nut 48 to be rotated by hand using the knurled rim 50 but constrain the nut 48 so that it cannot move along the threaded pin 46. Therefore, as the nut 48 is turned clockwise or anti- clockwise, the pin 46 is drawn forwards or backwards through the nut 48, carrying the second wheel support 38 with it and displacing the second wheel support 38 relative to the first wheel support 30. A knob 56 having an internally threaded blind bore is screwed onto the end of the threaded pin 46 and may be used to clamp the nut 48 in a desired position.

The cover creasing device is set up for use in the following manner. First the resilient strip 20 is adhered to the drum 2 as previously described. Next, the first wheel 4 is positioned relative to the drum 2 by adjusting the angle between the strut 34 and the frame (not shown) as indicated by the arrows 58 in Fig. 1. The first wheel 4 is correctly adjusted when the gap between the outer surface 14 of the first wheel 4 and the outer surface 10 of the drum 2 is such that the correct pressure will be exerted on a piece of card fed between the creasing rib 22 of the resilient strip 20 and the selected groove 16 of the first wheel 4. If necessary, the first wheel 4 can be adjusted vertically to ensure that the groove 16 is exactly aligned with the creasing rib 22.

Now that the first wheel 4 is correctly positioned, the second wheel 6 should automatically be close to its correct position. Fine adjustment of the gap between the second wheel 6 and the drum 2 can be effected by first unscrewing the clamping knob 56 to release the nut 48 then turning the nut 48 to move the second wheel mounting 38 towards or away from the drum 2, as indicated by the arrows 42 in Fig. 1. When the second wheel 6 is in its correct position, the clamping knob 56 can be re-applied.

In use, the shaft of the stitching machine (not shown) is driven to rotate the drum 2 in the anti-clockwise direction, as viewed in Fig. 1. A sheet of card is fed between the drum 2 and the second wheel 6, as indicated by the arrow 60 in Fig. 1, and is pressed between the outer surface 10 of the drum and the outer surface 14 of the second wheel. Continued rotation of the drum 2 draws the card between the drum 2 and the wheel 6, causing the wheel 6 to rotate by frictional contact with the card and forming a linear crease in the card as it passes between the creasing rib 22 of the resilient strip 20 on the drum and the groove 16 in the second wheel 6.

After leaving the second wheel 6, the sheet of card then remains in contact with the drum 2 and passes between the drum 2 and the first wheel 4, where the crease is reinforced as it passes between the creasing rib 22 of the resilient strip 20 on the drum and the groove 16 in the first wheel 6. Finally, the creased sheet of card emerges from the device along the line indicated by arrow 62 in Fig. 1. Downstream processes may include folding the card along the crease and wrapping it around an insert to form a booklet.

Claims

1. A device for creasing card, comprising a rotary drum (2) and two wheels (4,6) mounted adjacent to the drum (2), such that a sheet of card may be fed between an outer surface (10) of the drum (2) and an outer surface (14) of one of the wheels (6) then between the outer surface (10) of the drum (2) and an outer surface (14) of the other of the wheels (4), to form a crease in the card between a rib (22) on the drum (2) and a groove (16) in each of the wheels (4,6) or between a groove in the drum (2) and a rib on each of the wheels (4,6).

2. A creasing device according to claim 1, further comprising a frame on which the drum (2) is rotatably supported, a first wheel support (30) on which a first one of the wheels (4) is rotatably supported and second wheel support (38) on which a second one of the wheels (6) is rotatably supported; wherein the first wheel support (30) is secured to the frame such that the distance between the first wheel (4) and the drum (2) can be adjusted; and wherein the second wheel support (38) is secured to the first wheel support (30) such that the distance between the second wheel (6) and the drum (2) can be adjusted.

3. A creasing device according to claim 2, further comprising means for changing the angle of the second wheel support (38) relative to the first wheel support

(30).

4. A creasing device according to claim 2 or claim 3, further comprising means for displacing the second wheel support (38) linearly relative to the first wheel support (30).

5. A creasing device according to claim 4, wherein the second wheel support (38) is secured to the first wheel support (30) with a dovetail joint (40) to allow relative linear displacement parallel to the length of the joint.

6. A creasing device according to claim 4 or claim 5, further comprising a screw thread (46) for controlling the linear displacement to adjust the distance between the second wheel (6) and the drum (2).

7. A creasing device according to claim 6, wherein the screw thread (46) is non- rotatably fixed to the second wheel support (38) and wherein a nut (48) on the screw thread (46) engages the first wheel support (30) in such a way that the nut (48) cannot move along its axis, whereby rotation of the nut (48) causes the screw thread (46) to move along the axis of the nut (48).

8. A resilient creasing strip (20) having two ends, a front surface along which is a creasing rib (22) and a rear surface along which is a locating rib (24) for locating the strip (20) in a circumferential groove (12) in the drum (2) of a creasing device.

9. A creasing strip according to claim 8, further comprising flanges extending laterally at each end of the strip (20) to form a pad (26), by which the strip (20) may be adhered to the drum (2) of the creasing device.

10. A device for creasing card, comprising: a rotary drum (2) having a circumferential groove (12) around its outer surface

(10); a wheel (4,6) having a circumferential groove (16) around its outer surface (14); and a resilient creasing strip (20) according to claim 8 or claim 9, the locating rib (24) of the strip being located in the groove (12) of the drum; wherein the wheel (4,6) is mounted adjacent to the drum (2), such that a sheet of card may be fed between the outer surface (10) of the drum and the outer surface (14) of the wheel (4,6), to form a crease in the card between the creasing rib (22) of the creasing strip (20) and the groove (16) in the wheel (4,6).

11. A creasing device according to claim 10, wherein the groove (12) in the drum (2) has a triangular cross-section and the locating rib (24) of the creasing strip (20) has a corresponding triangular cross-section.

12. A creasing device according to claim 10 or claim 11, wherein the wheel (4,6) has a plurality of circumferential grooves (16) of different widths.

13. A creasing device according to any of claims 10 to 12, further comprising a second wheel (4,6) mounted adjacent to the drum (2) as defined in any of claims 1 to 7.