FR2489204A1 - Band blade machine for slitting sheets of leather, plastic etc. - has blade and sharpening assembly horizontally adjustable in fixed main frame - Google Patents

Abstract

Machine for slitting sheet material e.g. leather, plastic, etc. into several, separate thinner layers, has a work table from which the sheet material is advanced by a pair of gripping feed rolls. The leading edge of the sheet is presented against the cutting edge of an endless band knife which is driven to move continuously in the plane in which the slitting cut is to be made. The cutting edge is continuously resharpened by passing between a pair of grinding wheels, positioned along the path of the band. The machine is now constructed as two main assemblies. The first assembly is rigidly fixed w.r.t. the machine foundation and includes the work table and relatively adjustable feed rolls, together with their driving system. The second main assembly is movable in a horizontal plane w.r.t. the first main assembly. It comprises a support bed for the band knife sub-assembly, with its drive and adjustments, as well as the blade-sharpening sub-assembly with its drive and adjustments. Very precise control of slitting consistency is achieved. The sheet material is presented to the blade by the first assembly which is rigidly mounted on the machine foundation. The second assembly complete can move only in a horizontal plane w.r.t. the first assembly, providing a rigid datum for all sub-adjustments.

Description

 The subject of the invention is a machine for slitting, in particular leathers and skins, non-woven textile products, rubber boots, plastics in sheets or rolls.

 The object of the invention relates to the technical sector of the treatment and mechanical transformations of hides and skins in particular.

 The slitting operation consists in separating into several layers, in their thickness, the materials or products worked.

 The machines known for carrying out this operation generally comprise and essentially a frame, a plan or work table on which the materials or products to be slit are presented flat, a device for driving said products or materials upstream of the cutting line, by means of two cylinders, one placed above the plane in which is the stretched strand of a cutting blade, flexible, endless, mounted on two flywheels of which at least one is motor and tensioner, the said upper cylinder being posfltionnd, relative to the plane of the stretched strand of the blade, in an adjustable manner according to the desired slitting thickness. The second cylinder which is placed below the plane of the stretched strand of the blade, is generally composed of independent cylindrical elements or rings, the said rings being aligned by the support against a metal ruler, the said rings being further supported and entrained by a cylinder with peripheral rubber lining, and driven in ro tation. The element or ring cylinder, which consists of sdpard elements, but mounted together, has the role of applying constant pressure to the products to be slit regardless of the thickness variations of the materials or products presented for slitting. .On the other hand, in addition to various adjustment systems, the slitting machines are usually equipped with a sharpening system of the endless blade, consisting of two grinding wheels each of which acts on one of the two faces in bevel constituting, at their intersection, the cutting edge of the blade.

 Except for certain adjustments, the elements of these machines are mounted fixed relative to each other.

 Known splitting machines have notable drawbacks.

 A first major drawback is that the conditions for slitting materials or various products: slitting thickness, density, structure, * o., Require changes in position between the edge of the cutting blade and the training plane, that is to say the fictitious plane passing through the axes of the driving and Dements cylinders. These modifications to the position of the edge of the cutting blade are effected by displacement of said blade relative to the members which support, guide, drive it, and which control its position and ensure sharpening. .It is then necessary to operate a series of compensating adjustments, in order to find, for a new position of the cutting edge, a suitable position for the grinding wheels, which constitutes a long, delicate and empirical operation.

 Another disadvantage of known slitting machines is that it is difficult for the operator to keep constantly in ddptt permanent sharpening, the position of the cutting edge or line at the appropriate level with respect to the thickness of the blade. This is explained if we consider that one of the bevelled faces is formed on the upper part along one edge of the blade, by a first grinding wheel. The other bevel face is formed by a second grinding wheel, on the lower part along the same edge of the blade.

 The sharpening actions of the two grinding wheels must be carefully set in order to ensure the quality of the blade and to keep the widths of the faces of the two bevels substantially constant and, consequently, so as to maintain the position of the cutting edge, relative to the thickness of the blade. These sharpening actions are at the initiative of the operator, who has no precise means of assessment, so that there are certain risks of adjustment.

 The slitting machine according to the invention overcomes these drawbacks by providing significant improvements as will appear from the following description.

 According to a first characteristic of the machine, its supporting structure is designed to separate the organs of said machine into two distinct assemblies, namely - a fixed assembly carrying devices for presenting, positioning and driving the products, devices placed on either side of the cutting line, which are separately and separately adjustable with respect to this cutting line constituted by the cutting edge of the upper strand stretched with an endless blade.

 - Uh assembly movable in the horizontal plane, with respect to the fixed part, comprising a blade support bench equipped with all the elements for guiding, positioning, driving, sharpening this blade, including the cutting edge formed at the intersection of two sharp bevel faces, in an immutable position in the horizontal plane, relative to the bench, the said movable assembly being movable relative to the fixed assembly of the structure, to modify the distance between the plane drive which is the fictitious plane passing through the axes of the driving and demented cylinders supported by the fixed part, and the cutting edge of the blade positioned immutable in the horizontal plane with respect to the mobile part.

 Another characteristic is in the Sit that the fixed assembly, resting on the ground, includes two vertical support batiks, braced to ensure parallelism, rigidity and stability, the said vertical supports carrying two guide rules parallel on which are placed the upper bridge and 1 lower support member, which ensure the presentation of the materials or products in front of the cutting blade and their drive 9 at the desired speed; the lower support member, carrying the ring cylinder or cylinder with elements comprising all the members necessary for positioning said cylinder, for guiding it, for maintaining it and for supporting it due to the presence of a cylinder coated rubber of determined hardness; the upper deck, carrying the driving cylinder comprising all the elements necessary for positioning said cylinder, for guiding it, for supporting it; the upper bridge and the lower support member are positioned on either side above and below the upper stretched strand of the cutting blade according to the characteristics of the slitting 9 to be produced, this by maneuvering means and positioning linked to the two parallel guide rules and integral with the frames.

 According to another characteristic, the mobile assembly, adjustable in position, comprises, mounted on a longitudinal bench, the support and drive blade cutting members such as flywheels with their rotation control devices, the blade tensioning members by movement of the flywheel axis, the blade guide members, the cutting edge position detection members to determine the advance of the blade as it wears and as the two bevelled edges are sharpened blade, the intersection of which forms the cutting edge; the bench resting on two boxes linked to the vertical support frames of the fixed structure and positioned parallel to the axes of the drive cylinder of the upper deck and of the cylinder with elements of the lower support, this positioning being modifiable, according to a movement parallel to it -same, thus ensuring rapid, precise and controllable adjustment of the distance between the drive plane and the cutting edge of the blade.

 The adjustment of this distance therefore takes place without modifying the relative positions of the blade guides, of the cutting edge detection device, of the sharpening devices, relative to the sharpened edge of the cutting blade. The interval between 1, edge of the cutting blade and the drive plane can therefore, because of this structure, be modified instantly, without additional adjustments, at best under slitting conditions. The lower this interval, the more precise the slitting will be; it being understood that below a certain value, the penetration of the material into the machine becomes more difficult.

 The breakdown of the slitter into two distinct sets, one fixed, carrying the support and product drive elements, the other mobile and adjustable relative to the first, carrying the cutting blade and all the elements that relate to this, also determines the possibility of controlling the barrel sharpening action. The automatic disengagement of the grinding wheels when stationary and their automatic action against the blade is obtained by the stop cylinder.

 The cutting edge of the blade having an immutable position relative to the support thereof, a proximity detection, mounted on the mobile assembly, positioned opposite one of the faces of the bevel of the blade, is able to report any abnormal displacement of the cutting line relative to the section of the blade in the vertical plane. Indeed, the ideal conditions of slitting corresponding to a given position of this cutting line in the thickness of the blade, too great an action of a sharpening wheel compared to the other can bring about the displacement of the cutting edge, the increase in the length of one of the faces of the sharpened bevel of the blade, in conjunction with the decrease in languor of the other face, this bringing about a modification of the working conditions and the degradation of the quality of the job.

 These characteristics and others will emerge from the description which follows.

To set the subject of the invention without however limiting it, in the accompanying drawings
Figure 1 is a schematic cross-sectional view of the machine according to the invention, in which only the fixed assembly has been illustrated.

 Figure 2 is a schematic cross-sectional view of the machine according to the invention, in which only the mobile assembly has been illustrated.

 Figure 3 is a schematic front view of the machine, in which there is illustrated the fixed assembly in solid lines and the movable assembly in broken lines.

 Figure 4 is a schematic plan view of the machine, in which there is illustrated the fixed assembly in solid lines and the movable assembly in broken lines.

 Figure 5 is a schematic view of the movable assembly in plan and section, seen along line 5-5 of Figure 2, that is to say in the slitting plane.

 Figure 6 is a schematic view of the mobile assembly in ptan and in section, considered along line 6-6 of Figure 2, that is to say in the axis of the connecting devices and adjusting the mobile assembly with fixed assembly.

 Figure 7 is a plan view and section on a larger scale illustrating the connecting and adjusting devices of the movable assembly with the fixed assembly.

Figure 8 is a sectional view of a larger scale trant one of the operating devices of the upper strand of the rear part tounée
Figure 9 is a sectional view of a larger scale with the rear part turned at 90, one of the sharpening devices of the cutting blade.

 Figures 10 and 11 are schematic views illustrating the two sharpening devices respectively in the working position and in the rest position.

 Figure 12 is a partial sectional view on a large scale, illustrating the device for detecting the cutting edge of the blade.

 FIG. 13 is a partial sectional view on a large scale, showing the device for detecting the distance of the upper bevel of the blade.

 Figure 14 is a schematic view illustrating the conventional adjustment of positioning of the cutting edge in a given slitting job.

 Figure 15 is a schematic view illustrating the positioning adjustment of the cutting edge according to the invention.

 In order to make the object of the invention more concrete, it is now described in a nonlimiting embodiment illustrated in the figures of the drawings.

 The slitting machine illustrated diagrammatically essentially comprises a fixed assembly and a mobile assembly.

 The fixed assembly includes, with regard to the main elements of its overall structure, two battis li and Id, braced by beams 2, keeping them parallel. Two rules 3q and 3d, clamped on the front faces of the frames 1g - 1d serving as guidance, on the upper bridge 4 carrying the driving cylinder 5, according to well known conventional arrangements, as well as on the lower support 6, carrying the cylinder with elements 7 positioned and guided, according to well-known arrangements, comprising ring-guide rule 8, rubber-coated support cylinder 9, work table 10 (FIG. 1).

 The lower support 6 is positioned by two adjustable stops lld and Ilq linked to rules B and 3d. The upper bridge 4 is positioned by two adjustable and synchronized devices 4d and 4 connected to stops 12q and 12d, with motorized control by 12h gearmotor group (Figure 3).

 The driving cylinder 5 and the rubberized support cylinder 9, the latter driving the cylinder with elements 7 by friction, are rotated for feeding the products into the machine, by a motor-rod group 65 of a good type. known, comprising two transmission shafts 65a - 65b connected to the cylinders 5 and 9 by constant velocity couplings 66 (Figure 3).

 The mobile assembly mainly comprises a longitudinal bench 13, mounted on two boxes 14g and 14d, connected and braced between them by a beam 15, thus forming a rigid and non-deformable assembly (Figure 3).

 The bench 13 rests on the faces 16d and 16g of the two astis Id and li (Figure 1) and is positioned relative to the latter by two operating devices 17d and 17q of the screw and screw wheel type, with nuts and screws , one end of which is immobilized by the supports 18d and 18 fixed to the astis ld and li. The operating devices 17d and 17g are linked in synchronism by a connecting shaft 18, and manually controlled from the outside of the machine by a shaft 19 equipped with an operating handwheel 20. These arrangements are evident from the figures. 6 and 7.

 A mobile carriage 21, suspended under one end of the bench 13, supports a motor shaft 22d, carrying a flywheel 23d, which is driven by an internal toothing controlled by an electric motor 24 (Figures 3 and 4). In contrast, the box 14q carries a shaft d fitted with a flywheel 23q.

 An endless blade 25 is mounted on the two flywheels 23d and 23q and the movable carriage 21 is biased by a hydraulic wheel 26 to ensure the tension of the endless blade 25 (FIG. 3).

 The upper strand of the blade 25 is guided by two counterblades 27 and 27a so that its movement takes place with a limited operating clearance (Figures 2, 3, 14, 15). The heel of the blade 25 is supported on a series of tungsten carbide-tipped keys 28 linked to a thrust plate 29, sliding prallele to itself in the main bench 13, and operated by three devices 30, 30d, 30q of the type screw-screw wheel with nut and screw (as seen in detail, Figure 8). The devices 30, 30d, 30a are linked in synchronism with each other by a transmission shaft 31 and maneuverable from outside the machine by a shaft 32 controlled in rotation by the geared motor group 33 (FIG. 5).

 The housings of the keys 28 in the thrust plate 29 are produced with precision so that the tungsten carbide faces of the keys 28 are in perfect alignment necessary to obtain rectilinear support at the upper strand of the blade in the end 25.

 FIG. 14 shows an example of configuration corresponding to a slitting job, for a given article, imposing for obtaining a correct result, a distance X, between plane of the driving rollers 5 and of elements 7, and the edge of the cutting blade 25. Starting from the position of the blade, characterized by the value X, the configuration on a conventional machine, for different articles requires, for example, a value X 'less than the value X. Obtaining of this value X ′ is produced in advance of the blade 25, determined by a displacement of a photoelectric positioning cell and in advance of the blade pushers 28.

 By the fact of this displacement of the blade 25 for passage of the blade aistance n a ia aistance A, ie aeDoraemenlspar in relation to its guides, increases, which decreases its good resistance between the counterblades 27 and 27a. Furthermore, the conditions for sharpening the two bevel blades will only be found by touching up the positions of the two upper and lower sharpening systems.

 In Figure 15, there is shown the position adjustment of the blade 25, on the machine object of the invention. The passage from the distance X to the distance X ′ is obtained by overall operation of the mobile part supporting the blade, relative to the fixed part supporting the drive cylinders 5 and elements 7. The overflow of the blade 25 outside its guides 27 - 27a is not changed, the grinding wheels, whose position is linked to the movable part, do not have to be changed. only the blade wear compensation adjustment remains, operated by the keys 28.

 A detection device by phokelectric cell 34, of a known type, that is to say comprising a transmitter 34a and a receiver 34b, detects the cutting edge of the blade (FIG. 12). This device mounted on a support 35 itself linked to the bench 13, determines the necessary advance maneuvers of the rear heel of the blade 25, pushed by the keys 28, by feeding the geared motor group 33. The cutting edge of the blade 25 is therefore ensured from an immutable position relative to the bench 13, because it is the cell which moves.

 Two grinding wheels 36a and 36b, mounted on two supports 37 and controlled in rotation by motors 38 and transmission by belts (Figure 2), ensure when they are ordered, the creation and maintenance of the two upper bevels 39 and lower 40 of the blade, bevels whose intersection defines the cutting edge of the blade (Figure 13).

The two supports 37 are of identical design and are arranged substantially symmetrically with respect to the blade 25. Each of these supports is operable by a device 41 of the screw and nut type, linked to an operating wheel 42 by a transmission 43 of the screw type - multiplier screw wheel (Figure 9). One end of the screw of the device 41 is linked to the piston 45 of a single-acting hydraulic cylinder 44, with return of the piston 45 by spring 46 (FIG. 9). The hydraulic cylinders 44 of the two supports 37 are clamped to upper 47 and lower 48 slides by brackets 55. A supply 44a by hydraulic group (not shown) at a given pressure, causes the springs 46 to be compressed and to be brought into abutment, of the two supports 37 in the context of the movement allowed to a stop 52 housed between a spacer 53 and a locking nut 54 in the position determined by the operating devices 41 (FIG. 9). Any interruption of electrical current in the power supply to the hydraulic unit causes the drop in fluid pressure and allows the relaxation of the spring 46 bringing
-9the release of the supports 37 and therefore the distance of the grinding wheels 36a and 36b in the rest position, relative to the two blade bevels 25, as illustrated in FIG. 11. Conversely, the pressurization of the hydraulic circuit acting on the piston 45, brings about the compression of the spring 46 and the displacement of the stop 52, thus ensuring the return to the working position, of the grinding wheels without it being necessary to intervene on the handwheels 42, as illustrated in FIG. 10.

 The upper 47 and lower 48 slides are one and the other mounted adjustable relative to the bench 13. The upper slide 47 is carried by a carriage 47a adjustable support by slide on the upper face of the bench 13, the trimming is operating by screw-nut device 49. The lower slide 48 is pivotally mounted on two hinges 50. linked to the front face of the bench 13. The pivoting operation of the lower slide 48 is ensured by operation of a screw-nut system 51 (Figure 2).

 Thus the upper grinding wheel 36a and the lower grinding wheel 36k can be positioned independently with respect to the edge of the endless blade, thus ensuring, according to the positions chosen by the adjustment systems 49 and 51, lengths of bevels more or less large according to the type of slitting to be done.

 The decomposition of the slitter according to the structure described above, allows the variation of the distance between the drive plane and the cutting edge of the blade without being modified in any way - keeping the blade 25 in constant overflow relative to the guide blade counter 27 and 27a, - the position of the cutting edge detection by photocell relative to the cutting edge, - the positions of the two grinding wheels 36a and 36b, relative to the two bevels forming the cutting edge.

 Parallel to the installation of the device 34 for detecting the edge of the blade 25 mounted on the bench 13 by means of the support 35, is clamped to the bench 13, a device for detecting the distance of the upper bevel 39 intended to control the correct maintaining the position of the cutting edge in the vertical plane (Figure 13).

 To this end, a support 56 bolted to the bench 13 has at one end a slide 56a linked. to a carriage 57 adjustable in height by operation of a screw 58 with knurled head 58a (possibly graduated) connected to the carriage and screwed into the support 56.

 An optoelectronic reflection detector 59 of the well-designed type is mounted on the carriage 57 opposite the reflecting face that constitutes the upper bevel 39. The proportion of reflected light flux is a function of the distance between the reference face of the optoelectronic detector and the face to be checked that constitutes the upper bevel 39 of the blade 25. For a given distance Y, the proportion of reflected light flux is 50% of the flux emitted and any modification of this distance, in one direction or the other, causes an increase or a decrease in the percentage of the reflected flow, and translated into electric current voltage, a reading bringing three pieces of information by indicator lights 60 - 61 - 62 to the control cabinet. We have for example 60 - correct position of the bevel , 61 - position of the bevel too high, 62 - position of the bevel too low.

 This information, locating the position of the bevel 39, in combination with the immutability of the cutting edge position in the horizontal plane controlled by the device 34, allows the slitter operator to accentuate or reduce the action of the grinding wheels. upper 36a or lower 36b thus ensuring the lability of position of the cutting edge relative to the two upper 25a and lower 25b faces of the blade 25 (FIG. 13). The permanence of this cutting edge height allows the constant maintenance of an essential component of the cutting conditions defined for a given job on a given product.

 The position in height of this cutting edge, in the thickness of the blade, therefore relative to the two faces of the latter, can be modified in one direction as in the other, according to the characteristics of the slitting , geometric characteristics or structural characteristics of the product to be split.

 The operation of the screw 58 by the knurled head 58a, causing a displacement in h-author of the carriage 57 carrying the optoelectronic reflection detector 59, makes it possible to define by reading the indicator lights 60 - 61 - 62, the action to be undertaken on one of the grinding wheels in relation to the other and to obtain the desired position once the "correct position" signal has been obtained.

 The advantages are apparent from the description.

 The invention is in no way limited to that of its modes of application any more than to those of the embodiments of its various parts having more particularly been indicated; on the contrary, it embraces all its variants.

Claims (7)

-1- Slitting machine, in particular leathers and skins, non-woven textile products, rubbers, plastics in plates, which mainly comprises a supporting or built structure (ld - zig), a plan or work table (10 ) to present the materials or products for slitting, a device for driving said products or materials by means of two cylinders (5 - 7) mounted in front of a cutting blade (25) and one of which (5 ) is placed above and the other (7) below the plane in which the stretched strand of the said endless cutting blade is carried carried by two flywheels (23d - 23g) of which at least one and motor and tensioner, the spacing between the cylinder (5-7) being adjustable, a sharpening system consisting of two grinding wheels (36a - 36b) of which Facune acts on one of the two faces (39 - 40) in a bevel constituting, at their intersection , the cutting edge of the blade, said machine being characterized in that its carrying structure is designed to separate the organs of the di the machine in two distinct sets, namely: a fixed set carrying the presentation devices (10), positioning and positioning (5 - 7) of the products, devices placed on either side of the cutting line, which are adjustable separately and separately with respect to this cutting line formed by the cutting edge of the upper strand stretched with an endless blade (2S); an assembly movable in the horizontal plane, with respect to the fixed assembly, comprising a blade support bench (13) equipped with all the elements for guiding, positioning, driving, sharpening this blade, the edge of which a skirt formed at the intersection of two sharp bevel faces (39 40), has an immutable position in the horizontal plane, relative to the bench; the said movable assembly being movable relative to the fixed assembly of the structure to modify the distance between the drive plane which is the fictitious plane passing through the axes of the drive cylinders (5) and with elements (7) supported by 1 fixed assembly, and the cutting edge of the blade immutablely positioned in the horizontal plane relative to the movable part. -2- Slitting machine according to claim 1, characterized in that the fixed assembly resting on the ground, comprises two vertical frames kld - îg) braced by due beams (2) to ensure parallelism, rigidity and stability, the said frames carrying two guide rules (3d - 3g) parallel on which are placed the upper bridge (4) and the lower support (6) which ensure the presentation of the materials or products in front of the cutting blade (25) and their drive at the desired speed; the lower support (6), carrying the cylinder with elements (7), comprises all the members necessary for the positioning of said cylinder (7), for its guidance, for its maintenance and for its support due to the presence of a rubber coated cylinder (9) of determined hardness; the upper bridge (4), carrying the cylinder-trainer (5), includes all the elements necessary for positioning said cylinder, for guiding it, for supporting it; the upper bridge (4) and the lower support (6) being positioned respectively above and below the stretched upper strand of the cutting blade (25), depending on the characteristics of the slitting to be carried out, this by means of maneuver and positioning (lld - they), (4d - 4g), linked to the guidance rules (3d - 3g) and to stops (12d - 12g) controlled by geared motor group (12h), these means being integral frames (Id - zig). -3- Slitting machine according to claim 1, characterized in that the movable assembly adjustable in position, comprises, mounted on a longitudinal bench (13), the support and drive members of the cutting blade (25) such as flywheels (23d - 23g) with their rotation control device (24), means (26) for tensioning the blade by movement of a carriage (21) relative to the bench (13), members ( 27 - 27a) for guiding the blade, members (34) for detecting the position of the cutting edge, and members (37) carrying grinding wheels (36a - 36b) for sharpening the two bevelled faces ( 39 - 40j of the blade; the bench (13) resting on two boxes (14d - 14g) connected and braced between them by a beam (15) to form a rigid and non-deformable assembly by its connection with the frames (ld - ig) said bench (13) being positioned parallel to the axes of the driving cylinder (5) of the upper bridge (4) and of the element cylinder (7) of the lower support (6) and in a reg lable according to a movement parallel to itself, thus ensuring rapid, precise and controllable adjustment of the distance between the drive plane and the cutting edge of the blade (25). -4- Slitting machine according to any one of claims 1, 2, 3, characterized in that the movable assembly is positioned relative to the fixed assembly by two operating devices (17d - 17g) of the screw and wheel type of screws, one end of which is immobilized by supports (18d - 18g) fixed to the frames (Id - ig) and which are linked in synchronism by a connecting shaft (18) connected to an operating means (19 - 20) external to the machine. -5- Slitting machine according to claim 1, characterized in that the adjustment of the distance between the plane passing through the cylinders (5 and 7) and the cutting edge of the blade (25) takes place after detection by the member (34), by overall operation of the movable part supporting the blade relative to the fixed part supporting the cylinders (5 and 7), thus keeping constant the overflow of the blade outside its guides (27 - 27a ). -6- Slitting machine according to claims 1 and 5 together, characterized in that the device for detecting the cutting edge of the blade (25) is of the emitter (34a) and receiver (34b) type with photocell. -electric, fixed mounted on the bench (13); the wear of the blade (25), say the sharpening carried out on the two bevels (39 - 40) of the blade, causes, due to the information given by the edge detection device, the actuation of a motor-reduction unit (33), bringing by synchronized operation of three devices (30, 30d, 30g) connected together by a shaft (31) and to the group - (33) by a shaft (32), the displacement of a push plate (29) fitted with blade heel pushers (28) produced and fixed precisely to be rigorously aligned. -7- Slitting machine according to claims I and 3 together, characterized in that the grinding wheels (36a - 36b) are mounted on identical supports (37) arranged substantially symmetrically with respect to the upper blade strand (25) and flanged at (55) on upper (47) and lower (48) slides; the slide (47) being carried by a carriage (47a) sliding on the bench (13) and maneuverable by screw-nut device (49), while the slide (48) is pivotally mounted by two hinges (50) on the face front of the bench (13) and operable by screw-nut device (51), -8- Slitting machine according to claims 1, 3 and 7 together, characterized in that the connection points (55) of the wheel supports (37 ) with their respective slide (47-48), carry a single-acting hydraulic cylinder (44) whose piston (45) with return spring (46), is connected to an operating means (41 - 42) by a reduction gear (43); pressurizing the hydraulic cricuit bringing the compression of the spring (46) and the displacement of a stop (52) fixed on the means (41), between two elements (53 - 54) of the jack, in the direction where the grinding wheels (36a - 36b) are spaced from the blade (25); conversely, the depression of the hydraulic circuit ensures the relaxation of the spring (46) and the reverse displacement of the stop (52) in the direction where the grinding wheels (36a - 36b) are in contact with the bevelled faces of the blade ( 25), without it being necessary to intervene on the maneuvering means (42). -9- Slitting machine according to claims 1, 3, 7 and 8 together, characterized in that the movable lwensible has a device for detecting the position of the upper bevel (39) of the blade (25) of the optoelectronic reflection detector type ( 59), mounted opposite the bevel (39) on a carriage (57) connected to a support (56) integral with the bench (13); any change in the percentage of light flux reflected by the bevel (39) is translated into electric current voltage on indicator lights (60 - 61 62) indicating the position of the bevel (39), namely: (60) correct position, ( 61) position too high, (62) position too low; this information in combination with the immutability of position of the cutting edge in the horizontal plane, allows the servant to accentuate or reduce the action of the grinding wheels (36a - 36b) to ensure the stability of position of the edge cutting with respect to the faces (25a - 25b) of the blade (25). -10- Slitting machine according to claim 9, characterized in that the optoelectronic reflection detector (59) is mounted adjustable in height by connection of the carriage (57) and the support (56) using a slide (56a ) and a screw (58) linked to the carriage and screwed into the support (56); the operation of the screw (58) by its gripping head (58a), possibly graduated, bringing about a displacement of the carriage, makes it possible to define by reading the indicator lights (60 - 61 - 62), the action to be taken on one of the grinding wheels in relation to the other and to obtain the desired position.