PRIOR ART

The problem of cutting scrap material pieces into smaller pieces is well known. One reason for doing this is that smaller pieces are often easier to collect, handle, and transport. The outer dimensions of a metal sheet, from which work pieces have been cut, may be large, but the amount of material left is usually low, making the sheet unstable, difficult to handle and unnecessarily bulky.

Another reason for cutting the scrap into smaller pieces is that the prices paid by scrap dealers for recycling of the scrap are higher if the scrap pieces are in such dimensions that they are easy to handle. It is desirable that the outer dimensions of the pieces are no more than 300 mm by 300 mm.

As cutting large quantities of scrap into smaller pieces manually would be strenuous and time-consuming as well as space-demanding, an arrangement for automation of this is desirable. Several attempts of such an arrangement may be seen in the prior art.

GB1131823 A discloses a device for cutting corrugated sheets with a rotating disc that may be lowered and raised into and out of a cutting position. As the disc only cuts in one direction, the result will be strips of material, the length of which may be up to the width of the sheets fed into the device. If the length of the strips is larger than desired, the strips will have to be fed once more into the device, in the transverse direction, for cutting into smaller pieces. This is time consuming, and the narrow strips run the risk of jamming in the device, which is primarily designed for wide sheets. GB 2143441 A discloses a hoop material cutter, which is designed to handle narrow strips of material well. Due to the original dimensions of the hoop material, i. e. a narrow strip, it will need to be cut only in one direction in order to achieve the desired maximum dimensions in all directions. The hoop material cutter includes one fixed blade and one movable blade, between which the hoop material is fed for cutting. The length of the blade is decisive for the width of the material that may be fed through the cutter.

In the art it is also known scrap cutting devices with a cutting blade of a complex shape. The main disadvantage of this type of cutter is that the cost for the blade and for the sharpening thereof is very high.

PROBLEM

With regard to the prior art, a cutting apparatus is desired for efficiently cutting pieces of material, with large dimensions, into smaller pieces, regardless of the original outer dimensions.

SOLUTION The object of the present invention will be attained, if the initially mentioned cutting apparatus is characterized in that the cutting blades are arranged on a cutting unit, which is movable back and forth along one edge of the sheet of material.

Further advantages will be attained if the scrap cutting apparatus is given one or more of the features of claims 2-11.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will now be described with reference to the attached drawings. In the drawings:

Fig 1 is a perspective view of an apparatus according to the invention; Fig 2 is a perspective view of a cutting unit included in the apparatus according to the invention;

Fig 3 is a perspective view from an opposite side of the cutting unit of fig 2; and

Fig 4 is a detail view in perspective of cutting blades included in the cutting unit of figures 2 and 3.

DESCRIPTION OF A PREFERRED EMBODIMENT

The present invention will now be described with the use of such words as upper, lower, sideways, etc. These words refer to the preferred embodiment in its normal position of use, i. e. as it is shown in fig 1. The description of the preferred embodiment does not, however, exclude other embodiments where the components and features are arranged differently, but according to the same inventive idea.

Figure 1 shows a cutting apparatus 1 according to the invention in perspective. This particular embodiment of the cutting apparatus 1 is a scrap cutting apparatus. There are other embodiments and uses of the cutting apparatus 1, as will be discussed below.

The scrap cutting apparatus 1 includes a feeding device 2, which transports the scrap towards a cutting zone at the forward end of the scrap cutting apparatus 1. A cutting unit 3 is movable back and forth along the forward end of the scrap cutting apparatus 1, for cutting the scrap into smaller pieces.

The scrap is typically a large metal sheet, from which a number of work pieces have been cut with as little waste as possible. It will thus often resemble a lattice, where the amount of metal is limited in relation to its outer dimensions, and it is highly desirable to cut it into smaller pieces.

The feeding device 2 is, in the preferred embodiment, a transversal, mobile girder 9, provided with retainers 7 for feeding the scrap towards the cutting unit 3. The retainers 7 will clamp the scrap material, inserted into the feeding device 2. By a motion of the transversal girder 9, the scrap material will be fed, on a bed 8 of the scrap cutting apparatus 1, towards the cutting unit 3 in the direction of the arrow A. Drive belts 10 are arranged for moving the transversal, mobile girder 9 at intervals. Each time the mobile girder 9 moves forward, the scrap material will be fed a distance forward. In the preferred embodiment, this distance will be corresponding to the desired dimension of the cut smaller pieces and to the capacity of the cutting unit 3. The distance is variable and selectable in the preferred embodiment in a range from 10mm up to the length of the cutting blades in the cutting unit 3.

The bed 8 and the cutting unit 3 are supported by a frame 5, which includes a transversal beam 6 at the forward end of the scrap cutting apparatus 1.

A sensor on the cutting unit 3, or on the bed 8, is provided to detect whether scrap material has reached the forward end of the scrap cutting apparatus 1, in which case the cutting unit 3 is activated. The cutting unit 3 is movable sideways along the forward end of the scrap cutting apparatus 1 by the action of an actuation means in the form of a drive belt 4. The drive belt 4 is arranged to move the cutting unit 3 sideways in steps corresponding to the desired outer dimension of the cut pieces in the transversal direction and to the capacity of the cutting unit 3. The length of the steps is selectable in a range from 1 mm up to the length of the blades of the cutting unit 3. A suitable length is decided with a view to the thickness of the material which is to be cut. The higher the thickness of the material, the less should be the length of the step before the cut is made. When the cutting unit 3 has been moved one step sideways, it is arranged, mechanically or electrically, to perform one cutting operation, provided that there is material to cut in the cutting unit 3. The result is that a smaller piece will be separated from the larger piece of scrap material on the bed 8. A chute 13 is arranged for the cut-off pieces to slide on, into a collection receptacle (not shown), which is placed in front of the cutting apparatus. When the cutting unit 3 has moved all the way along the edge of the scrap material on the bed 8, from one side of the scrap cutting apparatus 1 to the other side, cutting off pieces of material, it will revert to its original position by the action of the drive belt 4.

All the time when the sheet of material is cut, it remains in its position on the bed 8, only being fed forward as the smaller pieces are cut off its forward end. This means that the need for space around the cutting apparatus is limited.

The cutting unit 3 is also provided with a detector to ensure that there is material present in the cutting unit 3 before a cutting operation is performed. In the preferred

embodiment, when the cutting apparatus 1 is used for cutting scrap metal, large sections are often missing from the material, and there is no use in performing a cutting operation if no material is present in the cutting unit 3. The process of cutting up a sheet of material, with large areas of material missing, will be performed quicker if no unnecessary cutting operations are made.

In the preferred embodiment, the detector is a metal roll arranged with its axis transversal to the direction of movement of the cutting unit. Since the scrap material is assumed to be made of a metal in the preferred embodiment of the invention, the metal roll will be grounded as soon as it comes into contact with a piece of the metal. When the roll is grounded, a relay will emit a signal to the cutting unit 3, and as soon as the cutting unit 3 has moved one whole step as described earlier above, a cutting operation will be performed, and the material inside the cutting unit 3 will be cut from the sheet of material. In order to speed up the cutting process when large numbers of identical sheets of scrap material are cut, the cutting apparatus 1 may be programmed. This may be useful in processing scrap from manufacture in large series. The first time a sheet in the series is processed in the cutting apparatus 1, the apparatus 1 is placed in a "teach mode", where movements of the cutting unit 3 and of the feeding device 2 are recorded in a memory, until the whole sheet has been cut into smaller pieces. When the next sheet in the series is fed into the cutting apparatus 1, the recorded sequence of movements and cutting operations is repeated, but the parts of the sequence where no cutting operations are made, i. e. where large sections of material are missing, are performed at a notably higher speed. The cutting unit 3 does not have to move in steps in these sections. Hence, the time needed for cutting the second and following sheets is reduced, and the process becomes more time and cost efficient.

In figure 2 the cutting unit 3 is shown separately. The cutting unit 3 is provided with two separate sets 11, 12 of blades for cutting the scrap. The first set 12, comprising two blades 12a, 12b, arranged at approximately right angles to one another, are fixed relative to the cutting apparatus 1. In the preferred embodiment of the invention, the fixed set 12 of blades are arranged below the second set 11 of blades.

The second set 11 of blades is movable so that a cutting operation is performable in cooperation with the first set 12 of blades. The blades 11a, 1 lb of the second set 11 are arranged at approximately the same mutual angle as the blades 12a, 12b of the first set. The second set 11 is arranged so that the bladesl la, 1 lb overlap the blades 12a, 12b of the first set during the cutting operation of the cutting unit 3.

Fig 3 shows the cutting unit 3 from a different angle than in fig 2. From this angle all the blades 11a, 1 lb, 12a, 12b are clearly visible. Also, the actuation means 14 for lifting and lowering the second set 11 of blades and performing the cutting operation are visible. After the second set 11 of blades have been lowered sufficiently to perform the cutting operation, the actuation means 14 will lift them again in a controlled manner to their original position, so that the cutting unit 3 will be ready for a further movement step along the forward end of the cutting apparatus 1.

The cutting edges of the blades 11a, 12a and 1 lb, 12b, respectively, which cooperate during the cutting operation, are arranged at a slight angle, as seen in fig 2 and fig 3. Hence a linear motion downwards of the second set 11 of blades will result in a cutting operation. The cutting edges of the blades 11a, 12a and 1 lb, 12b, respectively, meet at a single point at each instant, thereby cutting through the scrap material, in a scissor-like manner, when the second set of blades is moved towards the first, fixed set of blades in such a cutting motion. From the aforementioned facts and fig 2 and fig 3 it is obvious that the cutting unit 3 is able to make cuts with a length corresponding to the length of the blades 11a, 1 lb, 12a, 12b. Hence, when the cutting unit 3 is moved sideways along the forward end of the scrap cutting apparatus, and along the edge of the scrap material, the movement is arranged, mechanically, electrically, or with the aid of a computer, to be performed stepwise with steps no longer than the maximum length of cut, i. e. no longer than the length of the blades 11a, 12 a, which are approximately parallel with the edge of the scrap material, provided that material to be cut is present in the cutting unit 3. Otherwise the cutting unit may move longer distances, as described above. However, as the purpose in the preferred embodiment of the apparatus is to comminute large pieces of scrap material, there are no demands on the precision in this application, and the length of the steps need not be precise, as long as they are less than or equal to the length of the blades 11a, l ib, 12a, 12b.

By the same token, the feeding of the sheet of scrap material towards the cutting unit 3 by the feeding device 2 should be arranged not to exceed the length of the blades 1 lb, 12b, which are arranged approximately parallel with the feeding direction A. Fig 4 shows the two sets 11, 12 of blades separately. In this figure it is clear that the first, lower set 12 of blades is arranged in close vicinity of the second, upper set 11, so that the blades of the two sets 11, 12 will be able to pass close by one another, when the movable set 11 is moved by the actuation means 14 to perform the cutting. Since the blades 11a, 1 lb and 12a, 12b, respectively, in each set 11, 12 of blades are placed at an angle, cutting will be performed in two directions at the same time. The directions of cutting are transversal to one another, and in the preferred embodiment of the invention they will be approximately perpendicular.

Also, the mutual angles of the cutting edges of the upper and the lower sets 11, 12 are clearly visible in figure 4. Hence the cutting force will at each single moment be concentrated in one point in each direction of cutting, thereby ensuring an optimal performance of the cutting unit 3.

Finally, fig 4 shows clearly that there are two separate blades 11a, 1 lb, 12a, 12b in each set of blades. The blades 11a, 1 lb, 12a, 12b will be fairly easy to manufacture and sharpen, and in the preferred embodiment standard blades may be used, thereby reducing the cost for these parts of the scrap cutting apparatus 1.

ALTERNATIVE EMBODIMENTS

The cutting apparatus 1 which has been described may be varied in different aspects and adapted to different circumstances. Various features may be changed independently of one another, to form a large number of embodiments, as long as the basic concept of the invention remains the same.

For instance, the preferred embodiment has been envisaged to handle scrap metal, such as metal sheets, but other materials, such as plastics or wood, may be handled, with minor variations in the dimensions of the apparatus and of the quality of the cutting blades. The material detector would have to be adapted to the material, in a way that is obvious to the skilled person, so that other materials, which may be non-conducting, could be detected and hereby handled by the apparatus. Such detector means may be optical or mechanical sensors arranged on the cutting unit 3, on the bed 8, or both.

Also, the cutting apparatus may be used for other purposes than the cutting up of scrap material, especially since it is programmable. For instance it may be programmed to make one or more cuts in corners or in the front edge of the sheet of material that is handled by the apparatus 1. The purpose of this would be to manufacture a product or a part thereof, instead of comminuting sheets of scrap material. In this use of the apparatus, increased care would be taken to meet the precision requirements for the finished product. The actuation means for the movement of the different movable parts in the apparatus 1 may also be varied in ways that are obvious to the skilled person. For example, the drive belt 4 for moving the cutting unit 3 may be replaced with e. g. a linear motor, a hydraulic motor, an electric motor, a hydraulic piston, a lead screw, a rack, or a gear belt.

In the described embodiment, the cutting unit 3 is inactive when it returns to its original position, after having made cuts along the forward edge of the sheet of material. In certain embodiments the blades 11a, 1 lb, 12a, 12b are arranged to be rotatable, i. e. turnable, around an approximately vertical axis, so that the sheet of material may be fed forward and be cut when the cutting unit 3 moves in the opposite direction. This arrangement increases the total speed of the cutting operation. Also, when the cutting apparatus 1 is used for production, certain cuts are best performed when the cutting unit 3 moves in the opposite direction. In further embodiments, each set 11, 12 of blades comprises three blades. These embodiments allow three-sided cuts to be made in a sheet of material intended for production.

Also, if the cutting apparatus is used for scrap cutting, the embodiments with three blades in each set 11, 12 will allow for stepwise cutting in both directions of movement of the cutting unit 3. In such a use, only two of the blades in each set will cut through the material at each cutting operation, but the presence of the third blade, which is arranged at the back of the set, as seen in the direction of movement, will allow for the increased flexibility of use. When the direction of movement of the cutting unit 3 is changed, the blade that was previously at the back will now be at the front, as seen in the new direction of movement. Also the total speed of cutting a material sheet will be increased.

In the preferred embodiment, the blades of each set are arranged at approximately right angles with one another. In that case the actual lengths of the blades set the upper limits of the length of the movement of both the cutting unit 3 and of the feeding of the sheet of scrap material on the table. It would be possible to arrange them at different angles, provided that the lengths of the steps of movement of the cutting unit 3 and of the feeding of the transversal mobile girder 9 are adapted thereto. The maximum length possible for the steps of movement of the cutting unit 3 is decided by the projection of the blades 11a, 1 lb, 12a, 12b on the forward edge of the scrap material. Likewise the maximum feeding distance that is possible is decided by the projection of the blades 11a, 1 lb, 12a, 12b on the side edge of the scrap material.