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LEATHER-SPLITTING MACHINE AND RELATED WORKING METHOD

D e s c r i p t i o n

The present invention relates to a leather-splitting machine (merely referred to in the particular field as "splitting machine"), as well as to a leather working method to be carried out by said splitting machine.

It is known that the so-called splitting machines are used for dividing/cutting leather, hide or similar materials into layers so as to obtain semifinished products to be then sent to subsequent working stations

(for manufacture of shoe vamps, for example) .

Generally, a splitting machine has a work station at which the hide or leather piece is moved close to, or pushed against a blade operating frontally on the hide piece (which is divided lengthwise, i.e. in the thickness direction) .

After being submitted to the cutting action (in the thickness direction) , ^• • the two hide pieces slide respectively along the two sides of the blade and are unloaded from the machine.

Still in the leather working field, but in a quite different technical sector, suitable die cutting machines are known that carry out working operations on leather but not in the thickness direction. In fact, these die cutting machines operate on top of the leather piece in order to define differently-sized cloths with given edges using one or more blades that are substantially perpendicular to the leather itself.

While the just described known art has been adopted for many years and with many different improvements, it still has some drawbacks.

In fact, due to the features of the material to be worked (and the reduced thicknesses that are to be reached for the semifinished products) the blades must have a reduced transverse size or thickness and for that reason they are rather delicate and suffer from many problems in terms of wear.

In addition, wear of the blades, and therefore in particular of the cutting edges of same, involves decay- in the working quality and also makes it necessary to resort to frequent replacements of said blades, which will bring about an increase in costs and reduction in productivity.

A problem that is particularly felt in splitting machines resides in that the high friction value between the blade and leather (or better, between the two blade faces extending on opposite sides starting from the blade edge, and the leather pieces obtained by splitting) involves generation of many stresses both on the blade and on the leather piece being worked giving rise to working inaccuracies, high wear and ultimately high management costs.

Accordingly, it is an object of the present invention to conceive a leather-splitting machine (or splitting machine) and a related working method that are able to overcome the above mentioned performance limits.

The present invention particularly aims at conceiving a splitting machine in which adhesion of the leather

piece to the blade edge and/or the blade faces is opposed and prevented as much as possible.

The present invention also aims at producing a splitting machine that has a great resistance to wear (which "wear" in turn ^"* is intended as abrasive wear, adhesive wear between blade and leather, or fatigue wear) .

It is another aim of the invention to conceive a splitting machine that can obtain the above mentioned performance improvements also retroactively, i.e. on already operative machines through simple and quick modifications .

It is a still further aim of the invention to conceive a splitting machine that can operate with different types of blades, i.e ^" . fixed or movable blades (or combinations of fixed and movable blades), regrindable blades or blades of the "throwaway" type.

The features of the present invention can apply to splitting machines to be used in different sectors, i.e. suitable for the footwear sector, for leather goods, shoes, garments, furniture manufacture, for the automotive industry and for the tanning and leather working sector.

The foregoing and further aims are achieved by a splitting machine and ^' a related leather-working method in accordance with the present invention, which has the features shown in the appended claims and an embodiment of which is hereinafter illustrated by way of non- limiting example, with the aid of the accompanying drawings, in which:

- Figs. Ia, Ib, Ic, Id, 2a, 2b, 2c and 2d show diagrammatic views of different types of blade for a splitting machine in accordance with the invention; and

- Fig. 3 is a diagrammatic view of another part of a splitting machine in accordance with the invention.

The splitting machine in accordance with the invention substantially comprises at least one blade 2 which is adapted to divide a ^" leather or hide piece P in the thickness direction, and suitable actuating means 3 that in turn can be operatively activated on the leather piece P (being worked) to push it towards the blade 2.

Advantageously, the splitting machine in accordance with the invention further comprises high-frequency vibration-inducing means 4 that can be operatively activated on the blade 2 and/or the actuating means 3.,

Conveniently, if several blades are present in the splitting machine, said inducing means 4 can be activated on one or more of said blades .

From an operating point of view, the vibration-inducing means 4 is adapted to generate vibrations and/or oscillations and/or deformations (preferably elastic deformations) of the blade 2 and/or the actuating means

3; preferably, these vibrations and/or oscillations and/or deformations that are induced on the blade 2 and/or the actuating means 3, will have a frequency higher than or equal to 20,000 Hz or in other words will have a frequency that is comparable with that of the ultrasonic waves (generally indicated as being of about 20, 000 Hz) .

In any case, it is also possible, to the aims of the present invention, -to use lower stress frequencies of the blades (and/or the actuating means), such as frequencies of some ten (or also some hundred) hertz: 5 to this aim use of different types of inducing means 4 will be appropriate, as better specified in the following.

Coming back to the inventive concept of the present

■10 invention, it will be recognised that induction of high-frequency (and preferably ultrasonic-frequency)

. vibrations enables the adhesion effects between the

_; leather piece being worked and the parts of the splitting machine coming into contact with said leather

15 to be minimised; in other words, since the blade 2 (and/or the actuating means) is submitted to a vibratory state the mean period of which is less than the time necessary for the leather piece to generate adhesion to the surfaces of the machine pieces, those

20 phenomena of microscopic dragging that to a macroscopic level cause "sticking" of the leather piece to the different machine parts are not generated. This has a particularly advantageous influence on the edge of blade 2 and also on the blade faces extending from the

25 edge.

From a structural point of view, blade 2 can be a fixed blade (or it can also be a regrindable blade or a "throwaway" blade) relative to a machine body, or it 30 can be movable relative to a machine body. A particularly significant example of "movable blade" is represented by a common ^' belt blade wrapped on two flywheels driven in rotation.

35 With reference to the drawings, it is possible to

notice that blade 2 has an extension axis 2a (that for example, in the case of a fixed blade is simultaneously parallel to the blade edge and perpendicular to the movement direction of leather P) , while the vibration- inducing means 4 can act along at least one first operating axis 4a parallel to the main extension axis 2a of blade 2.

In this first embodiment, the blade edge is urged to move transversely of the movement/feeding direction of leather P under working; in this manner the efficiency of the cutting action is increased and the likelihood of the leather piece adhering to the blade close to the blade edge is greatly reduced.

Depending on operating requirements (on the type of leather to be worked or the feeding rate and so on) , it is conveniently possible that the vibration-inducing means 4 ^' be also active along at least one second operating axis 4b transverse, and preferably perpendicular, to the extension axis 2a of blade 2 and coplanar to the latter.

Still depending on current requirements, the vibration- inducing means 4 may also act along a third operating axis 4c emerging from a lying plane of blade 2.

Obviously, within the scope of the present invention the operating axes 4a and/or 4b and/or 4c can be combined with each other in any manner, following any amplitude combination and/or vibration step.

At the same time, the number and arrangement of the vibration-inducing means 4 can be selected depending on current requirements.

For instance, with reference to Fig. Ia, it is possible to notice the presence of a single vibration-inducing element 4 which acts on one end of blade 2 to impart an oscillation/vibration thereto along axis 2a parallel to the blade edge.

Looking instead at Fig._ Ib, it is possible to see the presence of a vibration-inducing element 4 acting on a blade face to cause vibration/oscillation of same according to a wave form modifying the planar character thereof.

Finally, in Fig. Ic it is possible to notice the presence of a vibration-inducing element still acting in the blade plane, but according to an axis perpendicular to the blade edge (which therefore will give rise to a winding course of the blade edge itself) .

As already said, the number and/or positioning of the high-frequency vibration-inducing means 4 can be of any type; for instance, two (or more) inducing elements can be located at different points of blade 2, and it is possible to cause operation of same in phase accordance, phase opposition or with an adjustable offsetting (possibly, the amplitudes of the stresses transmitted to the blade itself can also be adjusted and/or selected) .

A non-limiting example of the above is visible in Fig.

Id, where two inducing elements are opposed along an axis parallel to axis 2a of the blade and can operate in phase opposition, following a scheme according to

^■ which while an inducing element "pushes" blade 2, the other inducing element "pulls" it.

It will be appreciated that the resultant frequency and amplitude to which blade 2 is caused to oscillate/vibrate come from the oscillation frequencies/amplitudes imparted by the inducing means 4, from their phase relation and/or amplitude and from the frequencies of the blade 2 itself.

Conveniently, the splitting machine may comprise, as being part of its actuating means, a shaped support 3a (a so-called "fixed ruler") and a thrust roller 3b facing said shaped support 3a and defining, in cooperation therewith, a passage for the leather piece being worked.

This fixed ruler 3a has a lying axis 3c preferably transverse to a feeding direction of leather P under working; in this case it is advantageously possible for the vibration-inducing means 4 to operatively act on the fixed ruler 3a and/or the thrust roller 3b along a stress axis 4a parallel or transverse to the lying axis 3c.

As previously seen in connection with possible relations between blade 2 and the inducing means 4, different combinations (all falling within the scope of the present invention) are also possible as regards inducing of high-frequency vibrations/oscillations of the fixed ruler and/or the thrust roller.

For instance, with reference to Fig. 2a, there is only one vibration-inducing element 4 which acts on one end of the fixed ruler 3a to impart an oscillation/vibration to the latter along the lying axis of same.

On the contrary in Figs. 2b and 2c it is possible to notice the presence of a vibration-inducing element 4 acting on one face of the fixed ruler 3a to cause vibration/oscillation of same transversely of the lying axis.

As shown in Fig. 2d 'by way of example, two inducing elements are positioned at different points of the fixed ruler 3a, which elements can operate in phase accordance, phase opposition or with an adjustable offsetting (possibly, the amplitudes of the stresses transmitted to the blade itself can also be adjusted and/or selected) .

In more detail, in Fig. 2d, the two inducing elements are opposed along an axis parallel to the lying axis of the fixed ruler and can operate in phase opposition, following a scheme according to which while an inducing element "pushes" the "fixed ruler, the other inducing element "pulls" it.

It will be recognised that the resultant frequency and amplitude to which the fixed ruler is caused to oscillate/vibrate come from the oscillation frequencies/amplitudes imparted by the inducing means 4, from their phase relation and/or amplitude and from the frequencies of the fixed ruler itself.

In order to generate ultrasonic frequencies, the vibration-inducing means can be ultrasonic wave generators which generally comprise:

- an ultrasonic-frequency generator;

- one or more transducers associated with the ultrasonic frequency generator and adapted to convert the electric energy into mechanical energy, which

transducers generally are piezoelectric elements;

- one or more signal amplifiers (generally referred to in the particular field as "boosters"), associated with said one or more transducers and adapted to amplify and/or increase a gain of a signal correlated with said ultrasonic frequency; and

- ducting and diffusion means operatively acting downstream of the signal amplifier and directing the amplified ultrasonic frequency onto the piece of the splitting machine 1 in accordance with the invention.

On the contrary, if different frequencies are wished to be induced, the inducing means 4 may comprise electromagnetic inductors, vibrating masses or electric motors (or more generally, everything adapted to transmit an oscillatory mechanical stress to the blade 2 and/or the actuating means 3) .

It is also an object of the present invention to provide a leather-working method that can be typically obtained through use of the splitting machine described above and claimed in the_ appended claims, which method substantially comprises a first movement step (with suitable actuating means) to move the leather piece towards a blade, and a subsequent division or cutting step to split the leather piece in the thickness direction on the blade itself.

Advantageously, the present method further comprises a step of inducing high-frequency vibrations on the blade and/or the actuating means, and this method can be carried out by a splitting machine in accordance with the present description.

The invention enables achievement of important

advantages.

First of all, it will be appreciated that the parts of the splitting machine that can be submitted to vibration (i.e. one or more blades and/or the "fixed ruler") enable sliding of the leather piece being worked, avoiding occurrence of jamming or instantaneous increases in the friction/adhesion values; in this manner leather cutting takes place more quickly and in a more accurate manner.

At the same time, it will be recognised that optimisation of the , contact between the splitting machine parts and the leather piece being worked enables mechanical wear of the machine pieces to be reduced and the operating life of said machine to be extended; this in particular occurs for the so-called regrinding blades and the "throwaway" blades.

In addition, the just mentioned performance improvements are also achieved on the product being worked which is therefore more precise and less submitted to localised decays (and therefore more valuable although of a lower production cost) .