Rigid, floating cutting device

OBJECT OF THE INVENTION

0001The present invention relates to a cutting apparatus which will be termed rigid floating, for application in any pressure cutting process in which the linear cutting pressure is less than 10⁷ N/m and the tolerance in the cutting direction is greater than 0.2 mm, which signifies that with this apparatus it is possible to cut, among other things, sandwich-type panels of different compositions.

0002In more specific terms, these can contain layers of fabric, polyurethane foams, fibreglass, paper, etc., with different thickness.

0003A typical example of a sandwich employed in the manufacturing technologies of roof linings is that constituted by the following layers: paper, fibreglass, adhesive, polyurethane foam, adhesive, fibreglass, plastic film and fabric.

0004It is also possible to use this apparatus to cut other types of materials like plastics or metals with low hardness.

0005The cutting apparatus is specially suitable for use in the automobile industry, specifically in the production of motor vehicle roof linings, wherein simultaneously with the moulding of the roof the trimming of the surplus material thereof takes place, in the same machine and in the same operation.

0006The object of the invention is to be able to absorb the possible misalignments, wear, or imperfections of moulds and working machines, that is to absorb possible deviations in position of moulds, blades and presses within certain limits. This is because in any machine of the aforementioned type there is no "zero" tolerance, and however to achieve an adequate cut a perfect alignment of the elements which intervene is required, for which reason it is necessary that at least one of them be capable of adjustment until managing to fit completely on the other.

BACKGROUND OF THE INVENTION

0007In the field of practical application of the invention and up to the present time, three forms of cutting are known with a movement predominantly normal to the surface of the piece to be cut:: pressure cutting, cutting by shearing and impact cutting.

0008Pressure cutting is <b>characterised in that</b> the piece is held between blade and striking plate until the pressure applied by both reaches the value sufficient to cut the piece. In said cutting action blade and striking plate are gradually brought together until in the final instant in which the cutting becomes effective, direct contact takes place between the two.

0009In cutting by shearing, blade and striking plate have a relative movement such that the material is compelled to separate without there being substantial compressive forces present, and without the blade coming to rest directly on the striking plate at any time, in a manner similar to how a pair of scissors would work. It is also applied in cutting machines and moulds.

0010Impact cutting could be considered a variant of pressure cutting insofar as the configuration of mould and cutting elements is concerned. However in this case the speed with which the mobile part of the mould moves during the cutting operation is much greater so that the cutting force is applied only by the blade, whereby the striking plate simply serves to support the piece in the cutting area.

0011The cutting apparatus of the invention is applicable to pressure cutting systems, which in many cases of cutting and conforming linings is preferred over the other two systems because of its greater simplicity in implementation and reliability. However pressure cutting, to be effective, requires a very precise alignment between striking plate and blade, which limits its use and needs frequent and specialized operations of maintenance and alignment.

0012As an example can be cited <patcit id="pcit0001" dnum="US3269234A"><text>US 3 269 234</text></patcit> in which an automatic cutting machine and method for compensation of misalignment are disclosed.

0013Another example of the state of the art is <patcit id="pcit0002" dnum="GB1104390A"><text>GB 1 104 390</text></patcit>.

DESCRIPTION OF THE INVENTION.

0014The cutting apparatus of the invention comprises the features of claim 1 and is applicable to pressure cutting systems.

0015The cutting apparatus which the invention discloses centres its characteristics on the fact that the striking plate admits certain relative movements of alignment apart from the actual cutting movement. This implies a matching of the moving part to the fixed part, as well as self-alignment with time during the useful life of the cutting tool, and when the tool is exchanged between different machines.

0016In more specific terms it has been foreseen that the striking plate is floating, as a consequence of being mounted or resting on an elastic support.

0017Specifically forming part in the apparatus, as well as the steel blade, there is a striking plate also of steel, of sufficient thickness so as to retain its shape in the face of the action of the blade and the profile of which corresponds with that of the edge of said blade, but with the special particularity that the striking plate, in this case, is rigid and retains its shape and is mounted, simply resting or with the inclusion of an insulating layer, on an elastic support, preferably an elastomer, which permits through its own deformation that the striking plate adapts its position in order to match the profile of the cutting blade, correcting the defects or misalignments that may exist between the components of the mould and in the machine itself.

0018The striking plate must have a thickness of more than 4 mm, to avoid deformations in the same, that is to obtain the sufficient degree of rigidity therein, while the support must have sufficient elasticity to absorb the cutting pressure and distribute it evenly along the whole length of the striking plate, at the same time that its hardness has to be adequate to allow sufficient force to be transmitted to make the cut with deformations in the elastomer of less than 2 mm.

0019In more specific terms, the striking plate will be made of alloy steel for wear-resistant tools of the group F-500 (according to Spanish IHA standards), with surface hardness of between 40 and 60 HRc, or another material with similar mechanical properties.

0020The striking plate runs the whole cutting line and is formed by consecutive segments of at least 200 mm each, and whose width will lie between 4 and 100 mm.

0021The elastic support or elastomer will be of a thickness between 2 and 8 millimetres and have a Shore A hardness of between 75 and 95.

0022Between striking plate and elastic support it will be possible to include heat lagging with a thickness of between 0.5 and 2.5 mm, resistant to temperatures up to at least 250° C.

0023The join between the striking plate and the elastomer or elastic support is free, simply support, the movement of these being guided by the channel in which they are housed and restricted in the direction parallel to that of cutting by a fastening which maintains both elements within said channel.

0024The fastening to impede the striking plate from leaving the channel and allow the movement thereof at the same time, will be possible to implement in different ways, always through at least one of the sides of the striking plate.

0025An optional embodiment consists in mounting the blade in a similar form, leaving the striking plate fixed. In this case it is the blade that adapts its position to that of the striking plate as the cut takes place.

DESCRIPTION OF THE DRAWINGS

0026To complete the description that is being made and with the object of assisting in a better understanding of the characteristics of the invention, in accordance with a preferred example of practical embodiment of the same, accompanying this description as an integral part thereof, is a set of drawings wherein by way of illustration and not restrictively, the following has been shown: <ul id="ul0001" list-style="none"><li><figref idref="f0001">Figure 1</figref>. - It shows a schematic representation in side elevation of a rigid and floating cutting apparatus embodied in accordance with the object of the present invention, in which the blade appears separated from the striking plate.</li><li><figref idref="f0001">Figure 2</figref>. - It shows a similar representation to that of the previous figure, in the working position, that is with the blade pressed against the striking plate with the elastic support deformed in the end position of the cutting travel.</li><li><figref idref="f0001">Figure 3</figref>. - It shows a detail in cross section of an example of practical embodiment for the fastening of the striking plate to the mould.</li><li><figref idref="f0002">Figure 4</figref>. - It shows, according to a representation similar to that of the previous figure, a variant of embodiment for said fastening.</li><li><figref idref="f0002">Figure 5</figref>. - It shows schematically the relative movements of the blade and of the striking plate for a perfect alignment between the two.</li></ul>

PREFERRED EMBODIMENT OF THE INVENTION

0027In the light of the figures described, especially of <figref idref="f0001">figures 1 and 2</figref>, it can be observed how in the cutting apparatus which the invention discloses, there participate a blade preferably of steel (1), with a cutting profile (2) which can adopt any configuration in accordance with that foreseen for the piece to be obtained, said blade (1) intended to fall on a striking plate (3), also preferably of steel, for which a blade-receiving profile is defined which complements that of the blade in question, as is perfectly observed in <figref idref="f0001">figure 1</figref>, so that when the blade (1) advances toward the striking plate (3) it makes contact with the latter, applying force progressively until reaching the limit situation shown in <figref idref="f0001">figure 2</figref>, that is, until the cutting profile of the blade is perfectly coupled on the equivalent profile of the striking plate, and so that is this way the piece is totally cut.

0028To obtain this effect the striking plate (3) rests on an elastic support (4), preferably an elastomer which deforms as the blade (1) is pressed against the striking plate (3).

0029As previously stated, the striking plate (3) needs to have sufficient thickness to prevent it from suffering any type of deformation on receiving the action of the blade (1), specifically a thickness greater than 4 mm, while the elastomer (4) has to have a spring constant sufficient to absorb the cutting pressure and to distribute it evenly over the whole striking plate with a deformation less than 2 mm.

0030The most suitable values for the aforesaid parameters have been stated previously.

0031In the detail in cross-section of <figref idref="f0001">figure 3</figref> a first example of practical embodiment has been represented for the fastening of the striking plate (3) to the mould (5), specifically inside a channel (6) of the latter, in which example said channel (6) is of considerably more width than the striking plate (3), so that after the emplacement inside said channel (6) of the elastomer (4) and in the event of the insulating material (7), the securing is carried out with the collaboration of a wedge (8) press-fitted in the space of the channel (6) left free by the striking plate (3).

0032Nevertheless and as shown in <figref idref="f0002">figure 4</figref>, the striking plate (3) can be of the same width as the channel (6), so that said striking plate (3) with the elastomer (4) and the lagging (7) is secured to the mould by means of a fastening screw (9) located laterally with respect to the striking plate (3), the same as occurred with the press-fitted wedge (8) of the example of the previous figure.

0033From the structure described a number of advantages arise which can be synthesized in the following aspects: <ul id="ul0002" list-style="dash" compact="compact"><li>The apparatus allows the same tool to be used in different machines without the need for prior adjustments.</li><li>Additional manual work is not necessary to achieve good alignment, of the cutting tools when these are replaced, repaired or employed in different machines.</li><li>The pieces obtained can be mounted directly as they leave the moulding-cutting machine avoiding subsequent reworking operations.</li><li>Excessive or abnormal wear is substantially reduced in both the blade (1) and the striking plate (3), by achieving that in all the cycles the cutting force is distributed evenly along the whole cutting line and thereby preventing the force being concentrated in particular areas of the edge of the blade or of the striking plate. It is possible to make replacements without having to make alignments.</li><li>Its maintenance is simple, not requiring very specialized operatives.</li><li>Cutting faults can be resolved on the working machine itself.</li><li>The cutting quality is notably enhanced, assuring that said cut is produced under a wider range of circumstances.</li><li>It allows working with different values of cutting force which allows either working with different materials using the same tool or doing partial or marked cuts if so desired.</li></ul>