The present invention relates to an apparatus for cutting sheetlike material, such as gasketing material. In particular, it relates to an apparatus comprising a frame, attachment means for attaching a sheetlike material to the frame, a cutter mechanism movably disposed in the frame for cutting the sheetlike material, and drive means.

To make openings of various sizes and shapes in sheetlike materials, particularly in materials intended to be used as gaskets, has become an often repeated work stage, for instance in various service and maintenance jobs at power stations. When the pipe system for a power station or other plant has been designed, all factors facilitating the maintenance have been taken into consideration. The maintenance staff has exact information about the thicknesses and the diameters of the gaskets needed, and a required amount of gaskets of certain sizes are kept in store. It is, however, expensive to keep in store gaskets of every size needed for the pipe connections. Depending on the materials used, the gaskets may also harden when stored, or change shape, why it is not possible anymore to use them for the intended purpose.

For that reason, gaskets are often made directly on the site of installation by cutting from the sheet material a gasket of the size needed at any given time, whereby unnecessary storing is avoided. However, the cutting of the gasket is then the problem. The dimensions of the gasket needed are transferred to the surface of the gasket material by means of a template or the like, whereafter a gasket in accordance therewith is cut.

Various appliances for cutting gaskets have been developed wh ch are mainly hand-operated and therefore difficult to

handle. The cutters can, for instance, be provided with various knives that rotate and cut at the same time. The problem with these cutters is that it is usually possible only to cut the sheet to half of its thickness, whereafter the sheet has to be turned and the cutting is finished by cutting it from the other side. The accuracy to size has to be very high, especially when circular gaskets are cut. Cutting with hand-operated devices is slow and errors of measurement occur easily, which results in great material losses.

Gaskets can also be made by punching, but in that case an individual tool is needed for each gasket size, which restricts the use of punching at the site of installation.

It is an object of the present invention to eliminate the above problems and provide a new and improved apparatus for cutting sheetlike material. It is a specific object of the invention to provide an apparatus which is better suited than the apparatus of the prior art for cutting gasket material, especially for making circular gaskets.

The above objects of the inventions are attained by an apparatus according to the invention having the characteristic features set forth in the appended claim 1.

In the apparatus according to the invention, a revolving device for rotating the sheetlike material around its attachment point when cutting the sheetlike material, for instance into circular shape, is connected to the attachment means for the sheetlike material. The attachment means are preferably formed by a vertical shaft disposed at the attachment point and two anchor plates rotating in a horizontal plane on the vertical shaft. The material to be cut is preferably locked at its middle between the anchor

plates so that the anchor plates, when rotating, rotate the sheetlike material in a horizontal plane around the vertical shaft. The revolving device is preferably connected to the drive means by power transmission means. A coupling which, when the revolving device is subjected to an excessive frictional force, for instance when the material being cut is too thick or the cutting knife is blunt, is released and stops the revolving device can be disposed in the power transmission means.

In a preferred embodiment of the invention, the cutter mechanism is fastened to a guide plate which is movably disposed in the frame. The guide plate can be moved in relation to the attachment point of the material to be cut, away from it or towards it, depending on the size of the piece to be cut. Longitudinal guides which guide the motion of the guide plate are disposed in the frame. A guide beam which is disposed transverse to the direction of motion of the cutter mechanism and/or parallel with the cut to be made in the sheetlike material is attached to the upper part of the guide plate on the frame. The guide beam, which is movable by moving the guide plate, serves as a base for the material to be cut during the cutting operation.

In the cutter mechanism according to the invention, a knife mechanism is preferably used in which the knife performs a vertical reciprocating cutting motion. The cutting operation can be controlled by adjusting the vertical motion. A knife opening, large enough for the knife of the cutter mechanism to go through, is made in the guide beam, which serves as cutting base for the material being cut.

The front edge of the cover of the frame is provided with a scale which shows the distance of the knife opening of the guide beam from the point of the attachment of the

material being cut at any given time. The scale thus shows for instance the radius of the gasket, when a circular gasket is being cut. The guide beam is provided with reading means, such as a guide wire or a line formed in the beam, extending from the knife opening to the edge of the guide beam towards the scale, by means of which the knife opening of the guide beam and the knife can be positioned at the right distance from the attachment point of the sheetlike material. =..

In a preferred embodiment of the invention, the knife of the cutter mechanism is movably connected to a guide plate disposed in the frame so that the knife, when cutting, reciprocates vertically performing substantially a sawing motion. The knife is then fastened to a slide connected to the guide plate and reciprocates vertically along the surface of the guide plate. For accomplishing the reciprocating motion, a rotating elliptic wheel, parallel to the surface of the guide plate, is preferably disposed beneath the slide, against which wheel the slide is pressed for instance by a spring force. The rotary movement of the elliptic wheel is then transmitted as a vertical reciprocating motion to the slide and the knife attached to it. Two or several wheels mounted on bearings are preferably attached to the guide plate for guiding the movement of the slide.

In an embodiment of the invention, in which the drive means is arranged to rotate the revolving device by means of drive shaft, gear box and power transmission means, the drive shaft is additionally arranged to go through the guide plate and rotate the elliptic wheel locked to the drive shaft in the direction of the guide plate.

In order to ensure an even cut, the material being cut is

preferably supported at the cutting point also from above, for instance by means of two support wheels. The support wheels can be arranged to press the material on both sides of the cutting knife against the cutting base.

It is possible to make the cutting apparatus according to the invention quite small and it can, if desired, be put into a rectangular, sound-proof protecting casing, having substantially the following dimensions: length 1100 - 1300 mm, width 150 - 170 mm and height 140 - 160 mm. The protecting casing can be provided with separate supports and wheels to make it easier to move and handle it. When gasket materials of large size are to be cut, separate adjustable side supports can be attached to the protecting cover.

The invention provides a simple cutter for gaskets, by means of which gaskets of various sizes can easily be cut.

The cutting knife can be easily and accurately adjusted at the distance from the center of the gasket required at any given time so that a gasket accurate to size is achieved.

By help of the drive means the reciprocating motion of the knife of the cutter as well as the rotation of the material being cut is easily controlled.

Exemplary embodiments of the invention will now be described with reference to the accompanying drawings, in which:

FIG: 1 is a side view of a cutting apparatus according to the invention; FIG. 2 is a top view of the cutting apparatus shown in

FIG. 1; FIG. 3 shows the cutting apparatus of FIG. 2 provided with a turning support member;

FIG. 4 is a side view of the cutting apparatus shown in

FIG. 3 during a cutting operation; FIG. 5 is a top view of the cutting apparatus shown in

FIG. 4; FIG. 6 is a vertical sectional view of the means for attaching and rotating a sheetlike material according to the invention; FIG. 7 shows in detail a knife mechanism according to the invention as seen from the side in a direction substantially at right angles to the direction of movement of the sheetlike material; FIG. 8 shows similar to FIG. 7 another knife mechanism according to the invention; FIG. 9 shows in detail a support wheel arrangement as seen from the side substantially in the direction of the movement of the sheetlike material; FIG. 10 is a side view of a knife suited for a knife mechanism according to the invention; and FIG. 11 shows similar to FIG. 10 another knife suited for an apparatus according to the invention.

FIGS. 1 and 2 show an apparatus 10 according to the invention in a side view as well as a top view, before the sheetlike material is attached to the apparatus. The apparatus comprises a frame 12 with its cutter mechanism 14, a revolving device 16 for the material to be cut and drive means 18 such as an electric motor or the like. The power is transmitted through a drive shaft 20, a gearbox 22 such as a worm gear unit, and other necessary power transmission means 24, such as a cogged belt. The drive means 18 can be controlled for instance by a foot switch

(not shown in the figure) . The drive shaft 20 transmits the power needed, usually at a reduced speed, through the gearbox 22 by means of the power transmission means 24 to the revolving device 16.

The cutter mechanism 14 comprises, as can be seen from FIGS. 1 and 2, a guide plate 26 moving along longitudinal guides 25 in the frame and a guide beam 28 attached to its upper part, which serves as a cutting base for the sheetlike material during the cutting operation. The cover parts 12' of the frame 12 of the apparatus can for instance be made of ground steel plate.

The cutting knife 30 is arranged to protrude from the knife opening 32 formed in the guide beam 28. A guide wire 36 is disposed between the knife opening 32 and one edge 34 of the guide beam. The guide wire indicates by means of the stationary scale 38 on the frame, which can be seen through an opening 32 formed in the edge of the guide beam, the exact distance of the knife 30 protruding from the knife opening 32 to the attachment point of the material being cut. Instead of a scale and a guide wire, some other measurement means known per se, such as an IR distance meter, can be used.

The guide plate 26 and the guide beam 28, which are attached to each other, can be moved lengthwise in the frame 12 in the direction indicated by the arrow "a" of FIG. 2 guided by the longitudinal guides by means of wire wheels 40, 42, 44, conveying wires 46, 46' and a mechanical turning handle 48. The conveying wires 46 and 46' are attached to the turning handle 48, by means of which the cutter mechanism can thus be moved in the lateral direction of the apparatus.

For the cutting operation, the material to be cut is attached to the revolving device 16 between anchor plates 50, 50' to be rotated around a shaft 52. The shaft forms the central attachment point of the sheetlike material.

FIG. 3 shows the apparatus shown in FIG. 2, in which the guide beam 28 is moved closer to the attachment point 52 of the sheetlike material than in the figures shown earlier. A longitudinal support member 54, which at its one end 56 is attached to the frame so that said end 56 forms an axle around which the support member can be turned, is additionally disposed on the apparatus. In FIG. 3 the support member is being turned in the direction of the arrow "a", whereby the attachment member fastened to the other end 58 of the support member will meet the attachment point 52 of the sheetlike material. During the cutting operation, this end 58 is lightly locked to the attachment point 52 by a locking member 60.

A support wheel assembly 62, movable along the support member, is attached to the underside of the support member, which prevents the material being cut, such as a gasket, from coming off from the surface of the guide beam during the cutting operation. In FIG. 3, the support wheel assembly moves in the direction of arrow "b" until it is in the right position on the guide beam near the knife opening 32 to support the material being cut. Making use of the scale 38 and the guide wire 36, the guide beam is locked in the desired position by means of a locking member 64.

FIGS 4 and 5 show the apparatus according to FIGS. 1 and 2 when a circular gasket 66 is being cut. By using the scale 38, the guide beam 28 with cutter mechanism has been moved to its right place as regards the diameter of the gasket to be cut. The sheetlike gasket material 68 has been placed on the revolving device 16 and been attached by means of the anchor plates 50 and 50*' at the attachment point 52. The longitudinal support member 54 has been disposed on the material to be cut 68 so that the wheels 64 and 64' of the wheel assembly are positioned on both sides of the cutting

knife 30 pressing the gasket material 68 downwards against the upper surface 70 of the guide beam 28. A locking tube 72, which is attached to the revolving device, has been disposed at the other end 58 of the support member.

The revolving device 16 rotates the material 68 being cut in the direction of arrow "a" of FIG. 5. The unbroken line 74 illustrates the cut-out part of the gasket material and the broken line 76 the part still to be cut.

FIG. 6 shows the revolving device 16 more in detail. The shaft 52 of the revolving device is rotatably supported at its lower end in a beam 78 of the frame by means of a thrust bearing 77 and a shaft nut 77' and at its upper end by means of a locking member 72<' in the locking tube 72, which as can be seen in FIG. 4 is fastened to the end 58 of the longitudinal support member 54. The anchor plates 50 and 50' are disposed on the vertical shaft 52 and the members 80 and 82 rotating the anchor plates. The latter 82 is driven by the drive means 18 through power transmission means, such as a cogged belt 24, as shown earlier. The rotating member 82 in its turn rotates the rotating member 80. Between said rotating members, a coupling 84 provided for instance with a compression spring, which is released when the resistance force is excessive and prevents the driving power from being transmitted from the rotating member 82 to the rotating member 80. The gasket material 68 to be cut is placed on the shaft 52 between the top and bottom anchor plates 50 and 50'. The anchor plates are pressed against each other by means of a locking member 86.

FIG. 7 shows a cutter mechanism 14, which is adapted to be used in the apparatus according to the invention for bringing about a reciprocating motion. The knife 30 is attached to a slide 88, which in its turn is movably

connected to the guide plate 26. The slide 88 is guided laterally at both sides thereof by two wheels 90 mounted on bearings. Two springs 91 which tend to pull the slide downwards are attached to the lower part of the slide. Underneath the slide there is disposed in the guide plate an elliptic wheel 92, the rim 94 of which, when the elliptic wheel is turned into its vertical position, forces the slide upwards and when the wheel is turned into its horizontal position, permits the springs 91 to pull the slide 88 to its lower position. The knife 30 will thus reciprocate vertically when the elliptic wheel rotates.

In FIG. 7, a portion of the cover 28 of the guide beam 70, a portion of the material 68 being cut and a portion of the cut part 74 of the material and a portion of the uncut part 76 can be seen.

FIG. 8 shows another preferred cutter mechanism 14, which differs from the ones shown earlier in that the springs 91 pulling the slide 88 downwards are attached to a beam 93, which in its turn is attached to the slide. The springs are thus indirectly connected to the slide. Further the mechanism differs from the embodiment shown in FIG. 7 in that the elliptic wheel is in indirect contact with the slide. The elliptic wheel is arranged to press the slide indirectly through a wheel 95 mounted on a bearing.

FIG. 9 shows a wheel assembly 62 which is suited for pressing the gasket material downwards while it is being cut using an apparatus according to the invention. The wheel assembly 62, which comprises two wheels 64 and 64' rotating on the material being cut and pressing the material downwards, is positioned directly above the opening 32 in the guide beam 28 so that the wheels are positioned on both sides of the opening. The wheels are

connected to a longitudinal support member 54 by means of forklike member 96, as can be seen in FIG. 4. The cutter knife 30 protrudes from the opening 32 between the wheels pushed by the slide 88. In FIG. 9, the wheels are disposed on the inside of the fork but of course they can, if desired, be disposed on the outside of the fork.

The knife 30 shown in FIG. 7 is bevelled and straight- edged. FIGS. 10 and 11 shows two alternative curved knife types. The cutting part 30' of the knife shown in FIG. 10 is convex, and the cutting part of the knife shown in FIG. 11 is concave. The best suited type of knife in each case is chosen according to the material to be cut and its thickness.

In the beginning of the cutting operation to be performed using apparatuses shown i FIGS. 1 - 11, the diameter of the gasket needed is measured and the cutting knife is placed in its right position by moving the guide beam by help of the scale and by turning the handle. When a circular gasket is cut, the guide beam is locked in its place. A hole is formed substantially in the middle of the gasket material and the gasket material is placed on the shaft of the revolving device between the anchor plates and locked there. The point of the knife is pushed through the gasket material and the wheels of the wheel assembly are disposed on the material to be cut on both sides of the cutting knife, and the longitudinal support member is locked in its place above the cutter mechanism. The cutter is put in motion, for instance by starting the drive mechanism by a foot switch. The outer periphery of the gasket is cut first, after which the guide beam is moved into a new position nearer to the attachment point of the gasket, and the cutting operation is repeated by cutting a circular opening in the gasket. By means of the apparatus according

to the invention, gaskets of various sizes, from small gaskets having a diameter of 45 mm to large gaskets having a diameter of up to 1400 mm, can easily be cut accurately to size at the site of installation.

It is obvious to a person skilled in the art that the different embodiments of the invention can be modified within the scope of the appended claims. By means of the apparatus it is for instance possible to cut gaskets of other than circular shapes by moving the guide beam during the cutting operation, whereby gaskets of any desired shape can be obtained.