Cutting head for sheet-like products, particularly fabrics for the clothing industry

Abstract: A cutting head for fabrics for the clothing industry, includes a body (4) which can move in a direction which is substantially parallel to the plane of arrangement of the products to be cut and supports a cutting blade (8) which oscillates transversely with respect to the plane; the head has electromagnetic means (A, B) which act directly on the blade to cause its controlled oscillation.

Description: The present invention relates to a cutting head for sheet-like products, particularly fabrics for the clothing industry. Machines for cutting flexible sheet-like products with a mechanically actuated cutting head are known. The head supports a cutting blade which is subjected to a reciprocating motion by means of mechanical transmission means which are in turn connected to an electric motor of preset power. Each type of machine has to be provided with an adapted motor having technical characteristics adequate to the physical and qualitative characteristics of the material to be cut, as well as to the thickness and number of layers of the products being processed. These known types of machine are not free from disadvantages. For example, in order to vary the cutting characteristics of the head, such as the frequency, the extent and the power of the blade's motion, it is necessary to provide adjustment devices which are rather complicated and difficult to maintain. The moving mechanical parts furthermore require frequent maintenance in order to prevent the failures and wear to which they are normally subject. These facts negatively affect the operating expenses of the machines as a whole, and contribute to increase the final cost of the product. Finally, the damage which notoriously arises from the sound pollution and from the vibrations produced by mechanically actuated machines should not be underestimated. From GB-A-2 168 642 a cutting apparatus is known which comprises all the features mentioned in claim 1. The driving mechanism of this known apparatus comprises eccentric members suitable for transforming the rotary motion of a motor into linear reciprocating motion of the cutting blade and therefore it suffers the typical disadvantages of the conventional driving mechanisms. From US-A-4 306 356 a punching machine is known which has an electromagnetic driving mechanism including a solenoid assembly enclosing a fixed core and a movable core captive to a plunger carrying the punch. The structure of the solenoid assembly is such that the movable core is only partially permeated by the electromagnetic field thus resulting in a reduced efficiency. Moreover, the control means for the driving mechanism is responsive to the movement of the housing with respect to the workpiece and cannot be adjusted at will. The aim of the present invention is to eliminate the disadvantages described above by providing a cutting head which, by virtue of its peculiar characteristics, has considerable flexibility and readiness in use, reduced operating costs, limited power losses and, the greatest reliability and safety in use. Within the scope of the above aim, a particular object of the invention is to reduce the number of mechanical moving parts to be subjected to adjustment. A further object is to provide a cutting head having component parts that can be obtained easily and can furthermore be rapidly assembled without requiring constructive complications. This aim, these objects and others which will become apparent hereinafter are achieved by a cutting head for sheet-like products, particularly fabrics for the clothing industry, according to claim 1. Other particular embodiments of the invention are set out in claims 2-9. Further characteristics and advantages of the invention will become apparent from the description of a preferred but not exclusive embodiment of the cutting head, illustrated only by way of non-limitative example in the accompanying drawings, wherein the only Figure is a transverse sectional view of a cutting head which is movably supported parallel to a plane of arrangement of the products to be cut and is connected to an electronic control unit. With reference to the above figure, the cutting head according to the invention, generally indicated by the reference numeral 1, is adapted to be associated with an element M of a per se known machine, which can move bidirectionally in a direction which is parallel to the plane of arrangement G of the products to be cut, following a path which is defined by the cutting plane. In particular, the head can be removably fixed to the element M by means of an anchoring head 2 which is fixed by means of bolts 3 or of other equivalent elements. The head 1 furthermore comprises an upper fixed body 4 and a lower slider 5 which can move in a direction which is substantially perpendicular to the plane of arrangement G of the products P, along guides 6 which are rigidly associated with the plate 2. Conveniently, a stop element 7 for a cutting blade 8 which protrudes beyond the anchoring plate 2 is provided at the free end of the slider 5. The blade 8 thus follows the movements of the slider 5 so as to interact with the products P to be cut. Advantageously, according to the invention, there are electromagnetic means which act directly on the blade 8 to cause its controlled oscillation. Said electromagnetic means comprise a fixed element, which is rigidly associated with the body of the head and is generally indicated by A, and a movable element, which is mounted on the slider 5 and is generally indicated by B. In particular, the fixed element A is enclosed within the upper body 4, which has a cylindrical symmetry, and comprises a central core 9, which also has a cylindrical shape and is provided with an axial through cavity 10. A substantially torus-like permanent magnet 11 is inserted between the body 4 and the core 9, and its constant internal diameter defines, together with the outer diameter of the core 9, an annular interspace 12. Advantageously, the permanent magnet 11 can be made of highly stable ferromagnetic materials, such as for example those belonging to the series of rare earths or lanthanoids. The movable element B is formed by a support 13 made of insulating material having a substantially cylindrical shape, on which a certain number of turns n of a conductor made of copper or the like is wound so as to define a solenoid 14. The assembly constituted by the solenoid 14 wound on the support 13 has such dimensions as to slide freely and within the annular cavity 12 coaxially thereto. The support 13 is furthermore rigidly fixed to the end of the slider 5 which is opposite to the blade 8 in a position which is approximately coaxial to said blade. The number of turns n, the diameter Φ of the conductor and the diameter D of the solenoid 14 can be determined as a function of the required power, by means of calculations which are within the capabilities of any expert in the field. Conveniently, the terminals of the solenoids 14 are connected, by means of conductors 15, 16, to a source of electric current L. If the energization current is alternating, the magnetic field generated by the solenoid 14 varies in a cyclic manner in direction and intensity, causing an oscillation in the slider 5 which in turn causes a reciprocating motion of the blade 8 with a frequency which is equal to that of the current and an extent which is variable according to the frequency and the cutting resistance opposed by the products P. In order to adjust the operating parameters of the head, there is an electronic control unit 17 which connects the movable electromagnet 10 to the electric power supply line L. The control unit 17 has, inside it, per se known circuits for adjusting the frequency and the current, as well as possible external indication elements, such as a digital display 18, and actuation means such as buttons or keys 19. The electric parts of the head can of course be provided with the usual safety devices provided for the equipment of machine tools. Elastic means, constituted by a spring 20 which is anchored to the slider 5 so as to support it in a position of equilibrium, can be interposed between the fixed part and the movable part of the electromagnetic means. Finally, in order to accurately guide the movable part with respect to the fixed part there is a central rod 21 which is rigidly associated with the slider and can slide within the axial cavity 10 of the core 9, with the optional interposition of a sliding sheath 22 made of antifriction material. Adjustable abutments, made of shock-absorbing material, can be provided in the wall of the core which faces the slider, in order to avoid unwanted overrunning strokes. From what has been described above, the operation of a cutting head according to the invention is apparent and can be summarized as follows. The element M of the cutting machine is moved by per se known motor means, pulling the head 1 along the plane of arrangement G along the contour of the products P to be cut. The control unit is adjusted beforehand so as to select the most appropriate values for the frequency and intensity of the solenoid's energization current. During the movement of the head, the blade oscillates about its equilibrium position, exploiting the principle of electromotive forces typical of electric motors. From what has been described above, it is apparent that the invention achieves the intended aim and objects; in particular, the extreme constructive simplicity, as well as the great economy and the safety in operation of the device are stressed. In practice, the materials employed, so long as compatible with the contingent use, as well as the dimensions, may be any according to the requirements and to the state of the art. Where technical features mentioned in any claim are followed by reference signs, those reference signs have been included for the sole purpose of increasing the intelligibility of the claims and accordingly, such reference signs do not have any limiting effect on the scope of each element identified by way of example by such reference signs.

Claims: Cutting head for sheet-like products, particularly fabrics for the clothing industry, comprising a body (4) movable in a plane parallel to the arrangement plane of said products (P), a cutting blade (8) movably mounted on said body (4) for oscillating in a transverse direction with respect to said plane, driving means operatively connected to said cutting blade (8) to promote its controlled reciprocating motion, characterized in that said driving means are electromagnetic means comprising a stationary element (A) attached to said body (4) and a movable element (B) directly connected to said cutting blade (8), said stationary element (A) including a substantially cylindrical ferromagnetic core (9) arranged inside a substantially torus-like shaped permanent magnet (11) so as to define an annular interspace (12), said movable element (B) including a substantially cylindrical electromagnet (14) freely and coaxially movable within said interspace (12), said electromagnet (14) being connected to a source of alternating current by means of an electronic control unit (17) suitable for varying the intensity and frequency of the energization current. Cutting head according to claim 1, wherein said body (4) is rigidly associated with an anchoring plate (2) which supports sliding means extending in a direction perpendicular to said arrangement plane. Cutting head according to claim 2, wherein said sliding means comprises guides (6) fixed to said anchoring plate (2) and a slider (5) movable along said guides (6). Cutting head according to claim 3, wherein said slider (5) comprises means (7) for removably securing said cutting blade (8). Cutting head according to claim 4, wherein elastic means (20) are provided for keeping said slider (5) in an equilibrium position with respect to said plate (2). Cutting head according to claim 4, wherein said movable electromagnet (14) is attached to one end of said slider (5) opposite to said cutting blade (8). Cutting head according to claim 4, wherein said movable electromagnet (14) is formed by an insulating support (13) on which a conductor is wound so as to define a substantally cylindrical solenoid. Cutting head according to claim 1, wherein said permanent stationary magnet (11) is made of highly stable ferromagnetic material. Cutting head according to claim 8, wherein said ferromagnetic material is chosen amongst the rare-earth series.

Inventors: PERON ALBERTO, PERON, ALBERTO
Applicants: PERON ALBERTO, TAMIELLO ALESSANDRO, PERON, ALBERTO, TAMIELLO, ALESSANDRO
Application year: 1991
Main classification: A41H43
IPC codes: B26D5, B26F1