Cutting device

Cutting device for cutting strips from a band of material (8). The cutting device is provided with an elongate upper knife (1) and a lower knife (2) that is movable in longitudinal direction along the elongate upper knife (1), for cutting the material (8) by the movement of the lower knife (2) along the upper knife (1). The elongate upper knife (1) can be swiveled to at least substantially abutting contact with the lower knife (2), wherein the swiveling comprises at least a component transverse to the elongate upper knife (1). The upper knife (1) can be swiveled to against the lower knife (2) by means of an electromotor, in particular a servomotor (5), wherein the upper knife (1) exerts a force on the lower knife (2).

BACKGROUND OF THE INVENTION

The invention relates to a cutting device for cutting strips from a band of material, according to the preamble of claim1.

Such a cutting device is known for instance from FR-A-2.729.336. Here a cutting device is being described with a swivable cover with a downwardly extending knife beam. The knife beam is swiveled downward to onto the material to be cut. A wheel-shaped lower knife is moved along the knife beam with the aid of a slide to cut the material. The lower edge of the knife beam is located under the upper edge of the wheel.

SUMMARY OF THE INVENTION

It is an object of the invention among other things to provide an alternative cutting device for cutting strips from a band of material, in particular a band of unvulcanised rubber, more in particular reinforced with a cord, with which the cut strips more often comply with the requirements made by the tyre manufacturers than the strips that are cut by the known cutting device.

For this purpose the present invention provides a cutting device for cutting strips from a band of material, in particular a band of unvulcanised rubber, comprising the features of claim1. By using an electromotor, in particular a servomotor, that can be swiveled to against the lower knife, wherein the upper knife exerts a force on the lower knife, wherein position and force can be controlled, it can be ensured that the cut of the knives is a straight cut. Because of this it is ensured that the long sides of the cut strips meet the requirements of tyre manufacturers. Here it is advantageous when the electromotor is a controllable electromotor, wherein preferably the cutting device is provided with a feedback device to keep the force with which the upper knife pushes against the lower knife at least substantially constant. A simple feedback device is realised when the feedback device is provided with a torque meter, in particular a current meter.

In one embodiment of a cutting device according to the invention the cutting device comprises a feed conveyor for conveying a band of material in the direction of the upper knife and the lower knife, wherein in particular the discharge end of the feed conveyor adjoins the lower knife.

A structurally simple embodiment of a cutting device according to the invention with which a cut strip can be realised, is obtained when the upper knife can be swiveled until it contacts the upper surface of the discharge end of the feed conveyor, wherein the cutting face of the upper knife adjoins the cutting face of the lower knife. A reproducible and accurate cut can be realised when the feed conveyor is provided with a pretensioning device for pretensioning the feed conveyor in the direction of the upper knife that has been swiveled until it contacts the discharge end. Here it is advantageous when the pretensioning device comprises an elastic element, in particular a spring. When the upper knife is provided with a roll element, it can be ensured that during contact of the upper knife with the band of material no undesired forces are exerted on it.

In an embodiment of a cutting device according to the invention the cutting device comprises a discharge conveyor to discharge a cut strip from the upper knife and lower knife.

In the known cutting device, and comparable cutting devices, the cut strip, after being cut, falls on the discharge conveyor. Because of this falling undesired changes in position and shape may occur in the strip, which changes have to be made undone or reduced by later operations. This drawback is at least partially resolved by the invention in that the upper face of the discharge conveyor and the upper edge of the lower knife are at least substantially positioned in one plane. Because of this changes in position and shape as a consequence of falling do not occur. Because of this later operations can be omitted or simplified.

A further improvement of the positioning of the cut strip on the discharge conveyor is obtained when the discharge conveyor is provided with a movable conveyor plane for discharging the strip, and with a holding magnet to hold the strip on the conveyance plane. Here it is advantageous when the operation of the cutting device is controlled such that the band of material is cut only when the band of material that is placed on the discharge conveyor is fixed with respect to the discharge conveyor by the magnet. In an advantageous embodiment of a cutting device according to the invention the holding magnet is arranged with its height movable with respect to the conveyance plane.

In a further preferred embodiment of a cutting device according to the invention the cutting device is provided with a displaceable transfer device for seizing the band of material on the feed conveyor and for transferring the band of material beyond the upper knife and lower knife to onto the discharge conveyor. Seizing and transferring the band of material in this way is more advantageous than pushing the band of material from the feed conveyor toward the discharge conveyor, known in some cutting devices, for as a consequence of this pushing changes in shape may occur in the band of material. Here it is advantageous when the transfer device is provided with a magnet beam for seizing the free end of the band of material.

In order to prevent the swiveling of the upper knife and the movement of the transfer device from adversely affecting each other, it is advantageous when the cutting device is provided with a device for synchronising the swiveling of the upper knife and for displacing the transfer device.

On the discharge conveyor cut strips are usually welded together, which welding is also known as splicing. In order to facilitate the positioning of the ends of strips that have to be spliced together in one embodiment of the cutting device according to the invention the feed conveyor is provided with a guide for guiding one edge of the band of material. An advantageous embodiment hereof is formed in that the guide of the plane of the feed conveyor comprises upright rollers. Here it is advantageous when the feed conveyor is adapted for moving the band of material in the direction towards and against the guide, in particular for this purpose the feed conveyor comprises conveyor rollers, the longitudinal direction of which forms an angle with the main line of the feed conveyor.

When the cutting device is provided with a device for measuring the length of the band of material, the result of the measurement can be used for the conveyance distance of the discharge conveyor to ensure that the ends of successive strips at least substantially adjoin each other.

A particularly simple way of splicing successive strips together is realised when the cutting device is provided with means for controlling the displacement of the transfer device so that the band of material is laid on the discharge conveyor so that the one edge of the band of material is in line with the guide. Such means can be formed in particular by a central spindle that is placed above the feed conveyor, from which spindle the transfer device is suspended and which spindle is located in the direction of forward travel of the feed conveyor. In an embodiment of a cutting device according to the invention in which the cutting device is provided with means for controlling the drive of the discharge conveyor so that the trailing end of an already cut strip becomes in line with the guide, the welding or splicing of strips can be realised accurately in a structurally simple manner.

A structurally simple cutting device can be realised when the feed conveyor is arranged pivotal about an at least substantially vertical axis with respect to the discharge conveyor, wherein the axis is located in the cutting line that is defined by the movable lower knife.

In an embodiment of a cutting device according to the invention or according to a further aspect of the invention the cutting device is provided with a splicer for splicing cut strips in a splicing location, said strips being located on a discharge conveyor, wherein the splicer is arranged displaceable with respect to the discharge conveyor. In known devices the splicing device is arranged in a fixed manner and the strips are conveyed in such a way that the splicing location will be exactly below the splicing device. The latter ensures that cutting, positioning and conveying the strips does in fact depend upon the splicing. By arranging the splicing device in a displaceable manner according to the invention, so that it can be moved to the location to be spliced, it can be ensured that all accompanying processes can be performed in a simpler and quicker way, wherein the accurate positioning is also at least maintained.

The aspects and features as described in this description and/or shown in the drawings can when possible also be applied individually. Those individual aspects, such as a movable lower knife, a swivable upper knife, the position of the upper side of the movable lower knife and the upper face of the discharge conveyor in one plane, performing the cutting of the band of material after the band of material has been fixed on the discharge conveyor, and other aspects can be the subject of divisional patent applications directed thereto. This holds true in particular for the features and aspects that are described as such in the sub-claims.

DETAILED DESCRIPTION OF THE DRAWINGS

InFIG. 1Ais depicted schematically a view in cross-section of a cutting device for cutting strips from a band of material, in particular a band of unvulcanised rubber, more particularly reinforced with a cord.

The cutting device is provided with an elongate upper knife1and a lower knife2that is movable along the elongate upper knife1. The lower knife2is a rotatable, at least substantially round, knife, that has a beveled cutting top3, which cutting top3is directed toward the upper knife1.

The elongate upper knife1can be swiveled to, at least substantially, abutting contact with the lower knife2, wherein the swiveling comprises at least a component transverse to the elongate upper knife1. In the embodiment as depicted inFIG. 1the upper knife1can be swiveled about a swivel axle4that extends parallel to the longitudinal direction of the upper knife1.

The swiveling of the upper knife1is effected by means of an electromotor, in particular a servomotor5, and this such that the upper knife1swivels to against the lower knife2, as can be seen subsequently inFIGS. 1Aup to and including1D. When the upper knife1abuts the lower knife2, the upper knife1exerts a force on the lower knife2. After the upper knife1abuts the lower knife2, the lower knife2is moved in longitudinal direction along the upper knife1for cutting material that is present between the upper knife and lower knife. Because of this a strip14,14′ (videFIGS. 4E and 4F) is cut off from the band of material8.

In the depicted embodiment the servomotor5is a controllable servomotor, that is provided with a feedback device6to keep the force with which the upper knife1pushes against the lower knife2at least substantially constant. The feedback device6comprises a torque meter, in particular a current meter, for measuring and on the basis thereof controlling the force with which the servomotor4pushes the upper knife against the lower knife. Although in the depicted embodiment the feedback device is provided in the servomotor, this feedback device may also be accommodated elsewhere.

As depicted inFIG. 1Athe cutting device comprises a feed conveyor7for conveying a band of material8in the direction toward the upper knife1and the lower knife2. The feed conveyor7is swivably bearing-mounted about a swivel axle9, and at the discharge end10thereof it is provided with a pretensioning device11. This pretensioning device11pushes the discharge end10of the feed conveyor7in the direction of the upper knife1. Because of this it is ensured that upon swiveling of the upper knife1into contact with the discharge end10, the band of material8is clamped between the upper knife1and the upper face of the feed conveyor7in a defined manner, because of which a good cut of the band of material8can be obtained. The upper knife1is provided with a roll element12to ensure that the upper knife1, when moving along the band of material8, does not cause undesired tensions and/or deformations in it and the band of material8is pushed onto the feed conveyor7.

The pretensioning device11comprises an elastic element, that, in the depicted embodiment, is a spring.

As depicted inFIG. 1Aall this is arranged such that the discharge end10of the feed conveyor7adjoins the lower knife2. When the upper knife1has been swiveled until it contacts the upper face of the discharge end10of the feed conveyor7, the cutting face of the upper knife1adjoins the cutting face of the lower knife2.

As depicted inFIG. 1Athe cutting device comprises a discharge conveyor13for discharging a cut strip14,14′ from the upper knife1and the lower knife2. In the embodiment depicted inFIGS. 1Aup to and including1F the upper face of the discharge conveyor13and the upper edge (the tip of the cutting top3) of the lower knife2lie in one plane. Because of this the cut off strip after cutting remains at the same height as the band of material where the latter is before cutting, which is favourable for the shape of the cut off strip. In other words, because the strip does not fall on the discharge conveyor, no undesired changes in shape occur.

In the embodiment as depicted inFIGS. 1Aup to and including1F the discharge conveyor13is provided with a movable conveyance plane for discharging the strip, and under the conveyance plane a holding magnet15is provided to hold the strip14,14′ on the conveyance plane. This holding magnet15is arranged with its height movable with respect to the conveyance plane.

As depicted among other things inFIG. 1Athe cutting device is provided with a displaceable transfer device for seizing the band of material8on the feed conveyor7and for transferring the band of material8to onto the discharge conveyor13. In the depicted embodiment the transfer device16is provided with a magnet beam17for seizing the free end of the band of material8. Here seizing/retaining and releasing the band of material again (reinforced with a cord) is facilitated in that the magnet beam17is mounted in a holder structure in a displaceable manner, as schematically indicated by the arrow inFIG. 1C.

In a manner that is known per se the cutting device is provided with a control unit (not depicted in the figures), such as for instance a computer or microprocessor, to control the mutual movements and the operation of the various components of the cutting device.

This control unit ensures among other things the synchronisation of the swiveling of the upper knife1and the displacement of the transfer device16,17.

The operation of the cutting device will be elucidated briefly on the basis ofFIG. 1.

InFIG. 1Athe situation is depicted in which a band of material8has moved up to the discharge end10of the feed conveyor7by the feed conveyor7. The upper knife1has been swiveled upward, and the transfer device has been brought into contact with the end of the band of material8in order to seize it. Subsequently the transfer device16moves to the left (as indicated by the arrow) and simultaneously the upper knife1is swiveled downward. When the transfer device16has reached the required position on the discharge conveyor13(FIG. 1B), the transfer device16is moved downward until the band of material has been placed on the upper face of the discharge conveyor13. The holding magnet15is moved upward, so that the holding magnet15fixes the band of material8in a position with respect to the discharge conveyor13. Subsequently the magnet beam17is moved upward within the bearing structure of the transfer device16(as depicted inFIG. 1C), so that the transfer device16releases the band of material8.

Meanwhile the upper knife1pushed the band of material8against the discharge conveyor7(FIG. 1D), wherein the discharge end10of the feed conveyor7is pushed downward somewhat against the action of the pretensioning device11. The transfer device16is moved to a waiting position in front of the upper knife1. Then the lower knife2is moved in longitudinal direction along the upper knife to make the cut and to form a strip (14, videFIG. 4E). When the cut is being made, the servomotor5with the feedback device6ensures that the force with which the upper knife1pushes against the lower knife2remains constant, so that the cut is most accurate. Because of the holding magnet15the cut off strip remains on the discharge conveyor in a defined manner.

After that the upper knife1is swiveled upward, the transfer device16is displaced to above the feed conveyor7(FIG. 1E), the strip is discharged by the discharge conveyor, and the holding magnet15moves to some distance under the upper face of the discharge conveyor13(FIG. 1F), after which the next strip can be cut off.

As depicted schematically in top view inFIG. 2Aand depicted schematically in side view (partly in cross-section) inFIG. 2B, the feed conveyor7is arranged pivotal about an at least substantially vertical axis18with respect to the discharge conveyor17. Here the axis18is located in the cutting line that is defined by the movable lower knife2. There the unity of feed conveyor7, discharge conveyor13and transfer device16is mounted on a frame19(FIG. 2B), which frame can have a relatively light weight in comparison with frames of known cutting devices. Because of the pivotal arrangement the cutting device can be most simply adapted to the various angles at which the band of material8has to be cut for a particular tyre to be manufactured.

The displacement of the transfer device16is controlled by means which comprise a central spindle20that is placed above the feed conveyor7and that is located in the direction of forward travel of the feed conveyor7. The transfer device16is suspended from said central spindle20. As depicted inFIGS. 2A and 2B, the transfer device is provided with a further magnet beam21for seizing/retaining the band of material8on behalf of the transfer of the band of material to the discharge conveyor13, although optionally this further magnet beam21may be left out.

As described above the discharge conveyor13comprises a holding magnet15for fixing the position of the strip with respect to the discharge conveyor13. This ensures that later processing of the strip, for instance splicing the strips to other strips, can take place in a more simple and accurate way. The cutting device comprises still further elements in order to perform this further processing in a more simple and accurate way, as will be elucidated hereinafter.

As depicted inFIG. 3the feed conveyor is provided with a guide22for guiding one edge23of the band of material8along a straight line24. In the depicted embodiment the guide22of the plane of the feed conveyor comprises upright rollers25. Here the feed conveyor is adapted for moving the band of material8in the direction toward and against the guide22. The feed conveyor may for instance be provided with conveyor rollers, the longitudinal direction of which forms an angle with the main line of the feed conveyor, so that the conveyor rollers direct the band of material toward the upright rollers25.

Because the central spindle20is located parallel to the direction of conveyance of the feed conveyor, it is ensured during the transfer of the band of material8by the transfer device16that the edge23of the band of material8is laid down on the discharge conveyor13so that said edge23becomes exactly in line with the line24on the discharge conveyor13(videFIG. 4C). Of course it is also possible to use measurement devices and feedback devices or other means for controlling the displacement of the transfer device so that the band of material is laid down on the discharge conveyor, so that the one edge of the band of material is in line with the guide.

The cutting device is furthermore provided with a device26(FIG. 3) for measuring the length of the band of material8i.e. the distance between the edge23(or the line24) and the opposite edge of the band of material8, which measurement device26may for instance comprise a camera, a laser, LEDs or the like in a manner that is known per se.

On the basis ofFIGS. 4Aup to and including4I the processes of cutting and splicing will be briefly elucidated.

InFIG. 4Athe starting position is schematically shown in top view. InFIG. 4Bthe transfer16has moved to above the end of the band of material8for seizing/retaining the band of material. InFIG. 4Cthe transfer device16has brought the band of material8along the cutting line to the discharge conveyor13and laid same down on it so that an edge23of the band of material8arrives on the line24.FIG. 4Ddepicts the situation in which the holding magnet retains the band of material8and the lower knife moves along the upper knife for cutting the band of material8so that the strip14is being formed. After that the strip14is discharged (FIG. 4E), wherein the discharge takes place along the measured length of the strip. Because of this the trailing end of the strip14will be positioned at least substantially on the line24.

Subsequently a next strip14′ is cut in the same way (FIGS. 4F,4G), and then discharged (FIG. 4H) along a length that has been measured for said strip14′. Here it is remarked that among other things by the transfer device, the holding magnet and the measured length, it is thus ensured that the trailing end of the previous strip14and the leading end of the next strip14′ will be positioned one against the other.

Above the discharge conveyor13a splicer27has been provided in a rest position. Said splicer27is not only adjustable in accordance with the angle at which the band of material is being supplied, but is also arranged displaceable in a direction parallel to the direction of movement of the discharge conveyor. This is contrary to known splicers which are arranged in a fixed manner.

After the next strip14′, based upon the measured width of said strip14′, has been discharged in the direction of the splicer27(FIG. 4H), the splicer27is moved such that it arrives exactly above the splicing location where the trailing end of the previous strip14and the leading end of the next strip14′ are positioned one against the other, after which the splicing is performed (FIG. 4I).

In this way a long succession can be formed of strips that are spliced together that may for instance be wound on a supply reel28or can be discharged directly for further incorporation into a tyre, such as a motor tyre or aircraft tyre.

The above description is included to illustrate the operation of preferred embodiments of the invention and not to limit the scope of the invention. Starting from the above explanation many variations that fall within the spirit and scope of the present invention will be evident to an expert, in particular as defined in the accompanying claims.