TECHNICAL BACKGROUND OF THE INVENTION

The present invention relates to an anvil drum for a rotary cutting apparatus having a rotary axis, comprising an axle on each axial side of the anvil and concentric with said axis, each of said axles being adapted to receive a bearing, and an anvil surface substantially concentric with said rotary axis.

It also relates to an anvil assembly provided with such an anvil drum and said bearings.

Such a rotary cutting apparatus is known from US-B-6 244 148, having the drawbacks that it is costy and cumbersome to disassemble it for maintenance, e.g. for re- grinding the anvil drum.

Another rotary cutting apparatus is known from US-A-4 770 078, which suffers from the same drawbacks.

The object of the present invention is to reduce the time and cost for performing maintenance of the known rotary cutting apparatus.

This has been achieved by an anvil drum as initially defined, wherein a reference portion, is provided, said reference portion comprising an axial reference surface coaxial to said axis and a radial surface perpendicular to said axis, and in that at least one connection means is provided for connecting a cover member on each axial side of the anvil so as to cover said bearing, respectively.

It has also been achieved by a an anvil assembly as initially defined, each cover member being provided with a blind opening adapted to be arranged coaxially with respect to said axis.

Hereby is achieved a possibility of protecting the bearings from grinding liquid during re-grinding thereof.

Advantageously, said connection means, comprises at least one axial threaded opening arranged in said radial surface, and a screw member, said radial surface being adapted to receive said cover member while leaving said axial surface free.

Suitably, said axle is provided with a peripheral axial surface, a central axial open- ing and an annular chamfer at said opening.

Preferably, said opening is a through hole. Alternatively, a blind hole may be provided in each axle.

Suitably, said cover member (68) is provided with at least two radially arranged centring screws, for centring the blind opening of the cover member in relation to said axial reference surface.

Advantageously, said cover member comprises a circular-cylindrical mantle, having a first and a second end and a lid covering said first end, the lid comprising said blind opening, and wherein said second end is adapted to abut said radial surface.

DRAWING SUMMARY

In the following, the invention will be described more closely with reference to the annexed drawings, in which

Figure IA is a front view of a first variant of a rotary cutting apparatus having a frame;

Figure IB is a magnification in-part of Fig. IA, parts of the frame being omitted;

Figure 1C is a rear view of the frame shown in figure IA, however in an open state;

Figures 2A and 2B are front and rear perspective views of a second variant of a ro- tary cutting apparatus;

Figure 2C illustrates an open state of the frame shown in figures 2 A and 2B.

Figures 3 A and 3C are front perspective views of a third variant of a rotary cutting apparatus;

Figure 4A illustrates the anvil shown in figures IA to 3B;

Figure 4B is a cross-section of the anvil shown in figure 4A;

Figure 4C is a magnification in-part of Fig. 4A;

Figure 5A illustrates the anvil shown in figure 4A provided with end caps; and

Figure 5B is a cross-section of the anvil with end caps shown in figure 5 A;

Figure 6 is a variant of the anvil and end caps shown in figure 5 A; and

Figure 7 is a further variant of the anvil and end caps shown in figure 5 A.

DETAILED DESCRIPTION

Figure IA shows a rotary cutting apparatus 2 comprising a frame 4 attached to a basement 6 by means of screws 8. A rotary cutting device 10 is removably attached

to the frame 4 by means of plates 12 securing cutter bearing housing 14 on either sides of a cutter drum 16 provided with at least one knife member 17.

An anvil 18 with an anvil drum 19 and having a substantially horizontal axis A-A (see also figure 4a) is arranged vertically above the rotary cutting device 10 and an axially peripheral surface 43 of the anvil drum 19.

A pair of levers 20 are rotatably arranged about a hinge 22, comprising an axle 23 journalled in bearings 24, the axle 23 having a substantially horizontal axis B-B and being attached to the frame 4 by means of screws 25a and a pair of L-shaped bars 25b, connected to a lid 26 of the frame by means of screws 25c. The lid 26 is connected to the frame 4 by means of four screws 26a, 26b, 26c, 26d (the latter being hidden).

The levers 20 are arranged on either sides of a vertical plane through the axis B-B of the anvil 18. Two pneumatic cylinders 27a are arranged substantially parallel to the hinge axis B-B and said rotational axis A-A and opposite to a vertical plane through the axis A-A. The cylinders 27a are adapted to co-operate with the levers 20, respectively, for turning them about the hinge 22. As can be seen in the figures, the horizontal axis (B-B) of said levers is arranged, seen in a vertical plane, above the rotary axis (A-A).

Figure IB shows furthermore that the inter-connection of the jacks 27a with the levers 20 comprises a link 27b provided with double hinges 28a, 28b, respectively. The pneumatic cylinders 27a are adapted to apply a substantially vertical force on the levers 20, respectively, via the links 27b, resulting in a rotation about the hinges 22 such that the levers 20 will perform an arc-shaped movement.

The anvil 18 is provided with a bearing housing 30, on either sides of the anvil drum 19. Each bearing housing 30 is provided with a coaxial opening 32 for allowing access to the interior of the bearing housing 30, and with a screw 34 covering an oil

filling hole 35 (see figure 4b). The bearing housing 30 is also provided with a radially directed threaded opening 36 (see figure 4a) for receiving a screw 38 in order to attach the bearing housing 30 to the lever 20.

During operation, the cylinders 27a will press the anvil drum 19 towards and against the knife member 17 of the cutter drum 16. Even though the levers 20 perform an arc shaped movement, it is so small that the movement of the anvil drum 19 towards and against the cutter drum 16 will be substantially vertical.

Figure 1C shows the rotary cutting apparatus 2 in an open state for allowing removal and maintenance of the anvil 18. This has been performed by attaching a detachable handle 39 to one of the L-shaped bars 25b, loosening the screws 26a, 26b, 26c and 26d and turning the lid 26 about the hinge 22.

In the position shown, a lifting device (not shown) can be attached to the openings 32 of the anvil 18 for lifting it away from the frame 4. After attachment of the lifting device to the anvil 18, the screws 38 (see Fig. IB) are loosened such that the anvil 18 is released from the levers 20.

Pneumatic cylinders have generally the characteristics that in the beginning of the movement of the piston, the force is not easily controllable, since the generated force will not be linear with respect to the applied pneumatic pressure in the cylinder. In order to overcome this problem, springs 39a are arranged to act on the end of the lever opposite to that of the hinge 22. The springs 39a will also counter balance the weight of the anvil 18, such that a minimum pressure is required for the anvil drum 19 to come into contact with the cutter drum 16 during use. The springs 39a will also prevent the anvil from colliding with the cutter drum 16, hereby avoiding damages of the knife member 17 and/or the axially peripheral surface 43 of the anvil drum 19.

Figures 2A and 2B show in front and rear perspective views of a second variant, according to which the anvil 18 is arranged underneath the cutter drum 16. In this embodiment, the cylinders 27a and the levers 20 are arranged underneath the anvil 18. The cylinders 27a thus subject a force directed substantially vertically upwards (see arrow) to the anvil 18 towards and against the knife member 17 of the rotary cutting device 10.

Also in this case springs 39a are provided for the same purpose as mentioned above.

The frame 4 forms an opening 4a, 4b on each side of a vertical plane through the axis A-A of the anvil 18.

Furthermore, the horizontal axis (B-B) of the levers is arranged, seen in a vertical plane, below the rotary axis (A-A).

As shown in figure 2C, the anvil 18 according to this variant is removed for service by placing a table or a wagon beneath the frame 4, unscrewing and removing the screws 38 for releasing the anvil from the levers 20 and then moving the anvil 18 it in a direction across the axis A-A through the frame opening 4a to the table or wagon. A lifting device now can be attached to the openings 32 of the anvil 18 for lifting it away for maintenance.

Figure 3 A to 3C show a third variant, according to which the anvil 18 and the levers 20 (omitted in figure 3B for better understanding) are arranged underneath the ro- tary cutting device 10, whereas the cylinders 27a are arranged above the anvil 18, in fact also above the cutting device 10, even though it would be possible to arrange the cylinders 27a at the same vertical level as the cutting device 10, i.e. beside it.

The piston rod 27b for of the cylinders 27a are each provided with a holding mem- ber 27c, shaped for receiving a horizontal crossbar 70 at two separate horizontal positions. The crossbar is connected to a pair of vertical bars 72, each of which being connected to one of the levers 20. A pair of guiding members 27d for guiding and

constituting stop members for the piston rods 27b. The guiding members 27d are rotatably connected to the frame 4 by means of a hinge 27e

When the cylinders are moved upwardly the anvil 18 will be moved towards and against the knife member 17 of the rotary cutting device 10, i.e. the anvil 18 will be subjected to a pulling force, as opposed to the force according to the first and second variants, according to which the applied force is a pressing force.

In this variant, the levers 20 are arranged on separate hinges 22a (hidden), 22b, each being provided with an axle 23a (hidden), 23b, the levers 20 being secured thereto by means of a nut 23c (hidden), 23d, respectively. The axles 23a, 23b are aligned with one another in order to form a common rotational axis B-B. The bearing housings 30 are provided with axially directed openings for receiving screws 40 in order to attach the bearing housing 30 to the lever 20.

Furthermore, the horizontal axis (B-B) of the levers is arranged, seen in a vertical plane, at about the same level as said rotary axis.

In figure 3C is shown how the anvil 18 is allowed to be removed for service. First the guiding members 27d are turned about the hinge 27e, allowing the piston rods to be retracted to a position not visible in the figure, i.e. inside the frame 4. The crossbar 70 is released from the holding members 27c, allowing the vertical bars 70 to be moved downwards (see arrow), in turn causing the levers 20 to turn downwards about the axis B-B. Then the screws 40, the nut 23d and the corresponding lever 20 are released and removed . The anvil 18 is now allowed to be pulled out from the frame along axis A-A.

The springs 39a have the same purpose as those shown in figures 1 A-2C.

Figures 4A and 4B show the anvil 18 with its anvil drum 19 and bearing housings 30.

In figure 4b, the anvil drum 19 has been shown as solid with integrated axle 42. The axially peripheral surface 43 of the anvil drum is centred coaxially with the axis A-A during its manufacture. The drum 19 may however instead be hollow, e.g. in the form of a sleeve, attached to the axle 42, i.e. constituting a separate part.

The bearing housing 30 comprises an axially directed ring 44 with a radially, towards the axis A-A directed annular protrusion 46, and an inner and outer cover 48, 50 in the form of an annular plate, respectively, together with the axle 42 defining a space 51 for a toroidal bearing 52a and an oscillating bearing 52b, to be arranged on the peripheral axial surface 42a (see figure 4C) of the axles 42, respectively, for avoiding constrainment and to take up any misalignments. The space 51 is filled with lubrication oil through the opening 35, which is closed by the screw 34. As already described above, the housing 30 is also provided with a threaded opening 36 for receiving the screw 38 (see figure IB)

The plate 50 is coaxially provided with an opening covered with a sealing ring 53 provided with a central coaxial opening 54 for allowing access to a central, coaxial through-hole 56 through the anvil 18 along the axis A-A, i.e. the drum 19 and the two axles 42. The purpose of the through-hole 56 is to allow lifting of the anvil for maintenance thereof.

The anvil 18, i.e. the anvil drum 19 or the axles 42, is furthermore provided with an integral reference portion 60 provided with a radial surface 61 and an axial annular reference surface 62 concentric with the axis A-A.

The portion 60 is furthermore arranged with axially directed threaded openings 64 for receiving a screw 66 (see figures 5A-5B), respectively.

In figure 4C is shown at the end of the axle 42 provided with an interior chamfer 67, constituting a reference surface for allowing centring of the anvil 18.

During manufacture of the anvil, the chamfer surface 67 is made first, then the anvil surface 43, the outer axial surface 42a of the axle 42 and the reference surface 62. Hereby, all of said surfaces are coaxial with the axis A-A. The bearings 52a, 52b can now be coaxially mounted on the axle 42.

For regrinding purposes of the anvil 18 are shown in Figures 5A-5B a cover member 68 in the form of a circular cylindrical mantle 70 and a lid 72, preferably being an integral part of the mantle 70, is arranged outside and concentric with the bearing housing on each side of the anvil drum 19, such that it abuts the radial surface 61 of the reference portion 60, leaving the annular reference surface 62 accessible.

As already stated above, each axially directed threaded opening 64 is adapted to receive a screw 66 for connecting the cover member 68 to each axial side of the anvil drum 19, i.e. to cover the bearings 52a, 52b during grinding for protecting them dur- ing machining of the anvil surface 43.

The lid 72 is provided with a blind hole 76 to be utilised during grinding as a centring point of the anvil in relation to the axis of the re-grinding machine. It also serves to support the anvil during the re-grinding operation.

The centring screws 74 ensure that the blind hole 76 is aligned with the chamfer 67, i.e. that the cover member 68 is concentric with the axis A-A.

The surface 62 is thus used for centring the blind hole 76, such that it is centred in relation to the axis A-A. This is important for positioning the anvil 18 correctly in the re-grinding machine.

The cover protects the bearings 52 from the cooling liquid during machining, and thus allows the bearings to remain on the axle 42, in turn avoiding the risk for dam- aging the bearings during disassembly thereof, since they can remain on the axle 42, in turn saving time during the maintenance of the anvil 18.

Figure 6 shows a variant, according to which the centring screws 74 not only centres the cover member 68, but also connect the cover member 68 to the axial ends of the anvil drums for covering the axles 42. This is performed by tightening the screws 74 towards the bearing housing 30, or by providing the bearing housing with threaded openings for the centring screws 74. In addition, or alternatively, the cover member may be made of a magnetic material

In order to seal the second end 71b of the cover member, it is provided with a seal- ing ring 61.

Figure 7 illustrates a further variant according to which a circular-cylindrical shaft 90 is pushed into the opening 56 . The shaft is provided with a male thread 92 at both ends for receiving a female thread 94 in the inside of the lid 72 of each cover member 68, for connecting and centring the cover member to the axis A-A.

Alternatively, the shaft 90 is pointed in both ends, and conical openings are provided in the inside of the lid for guiding the pointed shaft, while tightening screws 66 according to figure 5B.

It should be noted that the sealing member shown in figure 6 may be utilised in any one of the described embodiments.