A SKIN CUTTING MACHINE HAVING A ROTATING BELT AND MEANS FOR EXTRACTING THE CUT SKIN FROM THE HAIR SIDE

Abstract: The skin-cutting machine comprising a rotary belt and extraction device according to the invention comprises a bearing structure on which the following are disposed: a group for moving the blade on the belt, a group for advancing the skin toward the inlet and calibrating the thickness of the cut, and a group for extracting the top part of the skin after cutting, the extraction group comprising a movable mat hav­ ing its front coupling end disposed in the rear part of the cutting blade and extending across the entire useful operat­ ing width of the machine, a number of pressure rollers being mounted above the movable mat and at least some of them being driven in rotation, the top pan of the cut skin being insertable between the mat and the rollers, means being pre­ sent for connecting the motor of the group for advancing the skin towards the machine inlet to the motor for advancing the mat and the pressure rollers so as to bring about relative and corresponding speeds, means also being present whereby the portion of skin between the mat and the pressure rollers is pulled towards the exterior, so as to widen the side areas of the skin portion during cutting.

Description: The invention relates to a machine for cutting skins and comprising a rotary belt and a means for extracting the hair side of the cut skin. The skin-processing operations include cutting them in the thickness direction and thus separating the top or "hair" side of the skin from the bottom side of the skin or "split". This operation is performed by machines called cutting-machines and comprising a blade on a looped belt driven in rotation, in front of which the skin is placed and gripped between a top roller, usually motor-driven, and a bottom roller which may also be driven if required, thus keeping the skin in position in front of the blade during cutting and advancing the skin in controlled manner. The "split" side of the cut skin thereupon falls to the bottom of the machine into a collecting vessel or on to a belt which moves it to a collecting area, whereas the "hair" side of the skin, which is particularly delicate, is extracted from the machine by at least two employees, who check the correct tension during extraction so as to obtain the maximum regularity of cut and avoid damage to the hair on the extracted skin. This operation is particularly onerous for the employees and therefore there is a need to provide a cutting machine which automatically extracts the hair side of the skin after cutting, without use of labour. To this end it has been proposed to couple a conveyor means to the cutting-machine outlet so as to receive the hair side of the skin after cutting it and transfer it to a storage area. However, this embodiment, which uses apparatus outside the machine and independent thereof, cannot extract the skin in controlled manner by pulling it with the required strength and in the required direction during each phase, and consequently results in defective cutting and is useless in many cases, e.g. for cutting particularly thin, valuable skins. The problem is therefore to provide a cutting machine which automatically extracts the hair side at a speed of advance such that the group for insertion into the machine is adjusted to the extraction group, the tension being controlled during the entire cutting operation. These results are achieved by the invention, which provides a machine for cutting skins and comprising a rotary belt and an extraction device, which comprises a bearing structure on which the following are disposed: a group for moving the blade on the belt, a group for advancing the skin towards the inlet and calibrating the thickness of the cut, and a group for extracting the top part of the skin after cutting, the extraction group comprising a frame disposed at the side where the skin comes out during cutting and bearing a movable mat having its front coupling end disposed in the rear part of the cutting blade and extending across the entire useful operating width of the machine, a number of pressure rollers being mounted above the movable mat and at least some of them being driven in rotation, the top part of the cut skin being insertable between the mat and the rollers, means being present for connecting the motor of the group for advancing the skin towards the machine inlet to the motor or motors for advancing the mat and the pressure rollers so as to bring about relative and corresponding speeds, means also being present whereby the portion of skin between the mat and the pressure rollers is pulled towards the exterior, so as to widen the side areas of the skin portion during cutting. In a preferred embodiment of the invention, the motor for advancing a skin towards the machine inlet is a hydraulic motor, and the movable mat and the driven pressure roller or rollers have a single common hydraulic motor, hydraulically supplied in series with the motor for advancing the skin to the machine inlet, the outlet line of the motor for advancing the skin to the machine inlet being the supply line for the motor actuating the movable mat and the driven pressure rollers. In the extraction group of the cutting machine according to the invention, at least the side rollers between the pressure rollers are driven in rotation, the side rollers having a peripheral speed which is greater than the speed of advance of the movable mat. The movable mat in the extraction group is made up of a number of portions side by side and driven in one unit by the associated traction motor and forming a single surface for bearing and conveying the skin. The pressure rollers in the extraction group are borne at the front end of an oscillating frame mounted on the frame bearing the mat, adjustable means being present for loading the pressure rollers against the movable mat, and means for stopping the oscillating frame at the minimum permitted position of approach of the rollers to the mat. The means for loading the pressure rollers comprise loadable screw springs. The means for pulling the skin towards the exterior comprise helical raised portions on the surface of the outer rollers between the pressure rollers, in opposite directions relative to the two sides of the machine and the slope relative to the skin in the contact position, so that when the rotor rotates, they produce a component which thrusts the skin towards the exterior during the extraction phase. In an alternative embodiment, the means for pulling the skin towards the exterior comprise external rollers having a conical shape, widening towards the exterior, between the pressure rollers, so that when the roller rotates, they cause the peripheral part of the skin to be pulled faster than the central part and produce a component thrusting the skin towards the exterior during the extraction phase. The frame bearing the mat and the pressure rollers is movably mounted on the sides of the frame bearing the machine and can be moved from an operating position when the mat is adjacent the blade on the belt, to a position remote therefrom giving access to the belt for maintenance; to this end, means are present for moving the frame bearing the mat and the pressure rollers. In an embodiment of the invention, the mat-bearing frame is mounted on the top part of the machine frame via bearings rotating around a common horizontal axis, at least one controllable actuator being present and adapted to rotate the frame around the aforementioned axis between a lowered operating position and a raised position giving access to the belt for maintenance. In another optional embodiment, the mat-bearing frame is mounted on the bottom part of the machine frame via bearings rotatable around a common horizontal axis, at least one controllable actuator being present and adapted to rotate the frame around the last-mentioned axis between a raised operating position and a lowered position giving access to the belt for maintenance. In another alternative embodiment, the mat-bearing frame is mounted on a side part of the machine frame on bearings rotatable around a vertical axis, at least one controllable actuator being present and adapted to rotate the frame around the last-mentioned axis between an operating position adjacent the blade on the belt and a laterally rotated position giving access to the belt for maintenance. Other details will be clear from the following description with reference to the accompanying drawings in which: Fig. 1 is a general view, in section along plane I-I of Fig. 3, of a cutting machine comprising an extraction group according to the invention, which is movable by being raised; Fig. 2 shows the cutting machine in Fig. 1 when the extraction group is raised for maintenance; Fig. 3 shows the machine in Fig. 1 in plan view, in section along plane III-III in Fig. 1; Fig. 4 is a general view of a cutting machine comprising an extraction group according to the invention, the group being removable by rotation to the side; Fig. 5 shows the machine in Fig. 4 is plan view and in section along plane V-V in Fig. 4; Fig. 6 is a general view of a cutting machine comprising an extraction group according to the invention, the group being removable by tilting downwards; Fig. 7 shows an enlarged detail of the extraction group; Fig. 8 is a section along plane VIII-VIII of Fig. 7; Fig. 9 is a view in the direction IX in Fig. 7; Fig. 10 shows a detail of the extraction group in Fig. 7, seen in the direction X; Fig. 11 shown the hydraulic actuating circuit of the cutting machine, and Fig. 12 is a diagram of a skin to be cut. The cutting machine according to the invention, as diagrammatically illustrated in Figs. 1 and 2, comprises a bearing frame having two sides 1 supporting a bottom bridge 2 and a top bridge 3 comprising calibrating rollers 5 and 6, at least one roller, usually the top one, being motor-driven so as to advance a skin "P" towards a blade-bearing group 4 comprising an annular blade driven in rotation and adapted to cut the skin in the thickness direction while the skin is being held between the calibrating rollers 5, 6 on the bottom and top bridge respectively. The bottom of the machine is formed with a suitable recess for a conveyor belt 7 for removing the "split" side of the skin, which falls on to the belt after cutting. An extraction group 8 is disposed behind the blade 9 borne by the blade-bearing group 4 and comprises a conveyor mat 10 wound between end rollers 11 and 12 and a tensioning and guide roller 13, and also comprises a top pressure group 14, the entire device being supported on an internal bearing frame 15. In the form shown in Figs. 1, 2 and 3, frame 15 has a pair of sides 16 extending upwards and pivotably connected to the cutting-machine sides 1 by a bearing shaft 17. An actuator 18 connected to sides 16 is used for rotating the extraction group from an operating position shown in Fig. 1 to a raised position shown in Fig. 2 and giving access to the cutting machine for cleaning and maintenance operations. Fig. 4 shows an alternative means of holding the extraction group on the cutting machine, where the frame 15 is connected to a bracket bearing 19 held by a shaft 20 borne by a pair of side supports 21. An actuator 22 connected e.g. to bracket 19 as shown in Fig. 5, comprises a piston comprising a rack 23 engaging a toothed wheel 24 and is used for rotating the extraction group from the operating position to the position giving access for maintenance, as shown in Fig. 6 by a continuous line and a chain-dotted line respectively. Fig. 6 shows an alternative embodiment in which the extraction group is supported underneath by a frame 24 pivotably connected to sides 1 by supports 25; a pair of actuators 26 acting on levers 27 connected to frame 24 give access to the cutting machine for maintenance by tilting the extraction group downwards. Fig. 7 is a more detailed view of the extraction group, which comprises frame 15, by means of which the rear guiding roller 12 and the front guiding roller 11 of frame 10, borne at the front end of the group, are conveyed towards blade 9. Frame 15 bears the supports 28 of the top pressure group 14 which, as can be seen more clearly from Fig. 9, comprises three frames 29 rotatably mounted on a common shaft 30 which in turn is borne by supports 28. Co-operating end and central rollers 31, 32 respectively are rotatably mounted at the front end of frames 29. Each frame 29 has a load element 33 borne by a cross-member 34 and comprising a spring 35 whose load can be calibrated via a ring nut 36 which acts via a movable joint sleeve 37 on frame 29 so as to adjust the load of rollers 31, 32 against the conveyor mat 10. A bracket 38 projects from the rear of frame 29 and an adjustable screw 39 can abut against it, the screw being borne like element 33 by cross-member 34, so as to adjust the minimum distance of rollers 31, 32 from mat 10. The rear guide roller 12 of mat 10 is driven by a hydraulic motor 40 connected thereto by a geared transmission group 41. Motor 40 also controls rollers 31 via gearwheel 42 and transmission chains 43 and 44, whereas the intermediate roller 32 is left idle and is used only to press skin P against mat 10. Advantageously, rollers 31 have helical surface raised portions 45 facing in a direction such that when they rotate they transmit a component thrusting the skin transversely towards the exterior during the extraction phase so as to keep the skin in a state of sufficient tension towards the exterior to guarantee regular cutting, in the same way as is manually done by the employees on cutting machines which do not have an extraction group. The same result, in an alternative embodiment of the invention, can be obtained if the end rollers 31 are given a conical cross-section widening towards the exterior of the machine, so that the peripheral areas of the skin are pulled faster than the central part and a thrust component towards the exterior is transmitted to the skin during rotation. As shown in Fig. 8, the conveyor mat 10 is made up of two portions 10a, 10b actuated together by the common shaft of the rear rollers 12. Each portion of mat 10 has a tensioning roller 13, whose external bearing can be moved in a direction substantially parallel to the direction of motion of the belt, by an actuator 46 acting on a lever 47 holding the roller bearing as diagrammatically shown in Fig. 7, so as to ensure that the roller is centred during motion. The transmission ratio between roller 12 and rollers 31 is such that the speed of advance of the mat is less than the peripheral speed of rollers 31, so that when the skin is extracted its peripheral areas are pulled at a higher speed than the central area, as diagrammatically indicated in Fig. 12, where arrows F1, F2 show the various cutting routes required in the central area and the peripheral areas of the skin in order to take account of the greater length of the peripheral parts of the skin due to the convex shape of the animal's belly. This prevents the skin from creasing or piling up and thus possibly influencing the thickness of the skin when cut or causing irregularities in the advance and possibly damaging the chamfer of the skin, resulting in defects in the cut surfaces. The motor for driving the rollers for advancing the skin in the cutting machine is advantageously a hydraulic motor and is hydraulically connected to the motor for driving the conveyor mat 10 and the rollers 31. The corresponding hydraulic circuit is shown in Fig. 11. As shown by the drawing, the hydraulic circuit comprises a pump 48, drawing from a reservoir 49, which supplies a motor 50 for driving the rollers on bridges 2 and 3 and advancing the skin for insertion into the machine, via a group of guide valves 51. The return duct 51 of motor 50 constitutes the supply for the motor 40 driving the mat 10 and the rollers 31 via a valve group 53, which comprises a valve 54 guiding the motor 40 and a valve 55 for driving the actuator 18 or 22 or 26 and moving the extraction group from the operating position to the maintenance position in the various embodiments described by way of example. This method of collecting and supplying the motors in the machine enables the extraction speed to be made dependent on the speed of inserting the skin into the machine, which may vary with the extent to which the skin is slowed up by the employees who are responsible for inserting the skin and who manually adjust the cutting process by holding the skin when necessary to obtain maximum regularity in the cut. Under these conditions, when the skin-inserting motor 50 is slowed down the result is a corresponding slowing-down of motor 40 in the extraction group, thus preventing the extraction group, which advances at constant speed, from excessively pulling the cut skin and spoiling the cut. This ensures maximum regularity of cutting, so that the machine can be used either for skin before tanning or "in pelts" or for skin after tanning or "in blue", which is more delicate and thinner. Many variants can be introduced without thereby departing from the scope of the invention in its general features.

Claims: A machine for cutting skins and comprising a rotary belt and an extraction device, characterised in that it comprises a bearing structure (15) on which the following are disposed: a group (4) for moving the blade (9) on the belt, a group for advancing the skin towards the inlet and calibrating the thickness of the cut, and a group for extracting the top part of the skin after cutting, the extraction group (8) comprising a frame disposed at the side where the skin comes out during cutting and bearing a movable mat (10) having its front coupling end (11) disposed in the rear part of the cutting blade (9) and extending across the entire useful operating width of the machine, a number of pressure rollers (14) being mounted above the movable mat and at least some of them being driven in rotation, the top part of the cut skin being insertable between the mat (10) and the rollers (14), means (41) being present for connecting the motor (50) of the group for advancing the skin towards the machine inlet to the motor (40) or motors for advancing the mat (10) and the pressure rollers (14) so as to bring about relative and corresponding speeds, mean (31) also being present whereby the portion of skin between the mat and the pressure rollers is pulled towards the exterior, so as to widen the side areas of the skin portion during cutting. A machine for cutting skins and comprising a rotary belt and extraction device according to claim 1, characterised in that the motor (50) for advancing a skin towards the machine inlet is a hydraulic motor, and the movable mat (10) and the driven pressure roller or rollers (14) have a single hydraulic motor, hydraulically supplied in series with the motor (50) for advancing the skin to the machine inlet, the outlet line of the motor for advancing the skin to the machine inlet being the supply line for the motor actuating the movable mat and the driven pressure rollers (14). A machine according to claim 1, characterised in that at least the side rollers between the pressure rollers (14) are driven in rotation, the side rollers having a peripheral speed which is greater than the speed of advance of the movable mat (10). A machine according to claim 1, characterised in that the movable mat (10) is made up of a number of portions side by side and driven in one unit by the associated traction motor (40) and forming a single surface for bearing and conveying the skin (P). A machine according to claim 1, characterised in that the pressure rollers (14) are borne at the front end of an oscillating frame (29) mounted on the frame (15) bearing the mat, adjustable means being present for loading the pressure rollers (14) against the movable mat, and means for stopping the oscillating frame (29) at the minimum permitted position of approach of the rollers to the mat. A machine according to claim 5, characterised in that the means (33) for loading the pressure rollers comprise loadable screw springs (35). A machine according to claim 1, characterised in that the means for pulling the skin towards the exterior comprise helical raised portions (45) on the surface of the outer rollers (31) between the pressure rollers, in opposite directions relative to the two sides of the machine and the slope relative to the skin in the contact position, so that when the rotor rotates, they produce a component which thrusts the skin towards the exterior during the extraction phase. A machine according to claim 1, characterised in that the means for pulling the skin towards the exterior comprise external rollers having a conical shape, widening towards the exterior, between the pressure rollers (14), so that when the roller rotates, they cause the peripheral part of the skin to be pulled faster than the central part and produce a component thrusting the skin towards the exterior during the extraction phase. A machine according to claim 1, characterised in that the frame (15) bearing the mat (10) and the pressure rollers (14) is movably mounted on the sides of the frame (1) bearing the machine and can be moved from an operating position when the mat is adjacent the blade on the belt, to a position remote therefrom giving access to the belt for maintenance. A machine for cutting skins and having a rotating belt and an extraction device according to claim 9, characterised in that means (18) are present for moving the frame (15) bearing the mat and the pressure rollers. A machine for cutting skins, comprising a rotary belt and extraction device according to claims 9 and 10, characterised in that the mat-bearing frame is mounted on the top part of the machine frame via bearings rotating around a common horizontal axis, at least one controllable actuator (18) being present and adapted to rotate the frame (15) around the aforementioned axis between a lowered operating position and a raised position giving access to the belt for maintenance. A machine according to claims 9 and 10, characterised in that the mat-bearing frame (15) is mounted on the bottom part of the machine frame via bearings rotatable around a common horizontal axis, at least one controllable actuator (18) being present and adapted to rotate the frame around the last-mentioned axis between a raised operating position and a lowered position giving access to the belt for maintenance. A machine according to claims 9 and 10, characterised in that the mat-bearing frame (15) is mounted on a side part of the machine frame (1) on bearings rotatable around a vertical axis, at least one controllable actuator being present and adapted to rotate the frame around the last-mentioned axis between an operating position adjacent the blade on the belt and a laterally rotated position giving access to the belt for maintenance.

Inventors: FACCHI, RAFFAELE
Applicants: S.P.A. LUIGI RIZZI & C.
Application year: 1987
Main classification: C14B1
IPC codes: C14B1