FR2707202A1 - Immobilisation device for a rotary cutting-out cylinder - Google Patents

Abstract

The present invention relates to a device for fastening a cutting-out sleeve for a cutting-out cylinder mounted so that it can rotate on a drive shaft (3, 3'). This device is characterised in that it includes -a holding core (10) integral with the shaft (3, 3') of the cylinder, the external surface of which has at least one frustoconical region, - a cutting-out sleeve (11), the internal surface of which is pressed onto the external surface of the holding core (10) via a frustoconical contact surface, - means for supplying pressurised fluid which are capable of creating a fluid pressure at the said frustoconical contact surface, making it possible to bring about a slight temporary deformation of the cutting-out sleeve (11) in order to incease the diameter thereof, so as to promote its positioning relative to the holding core (10).

Description

 The present invention relates to a device for immobilizing a cutting sleeve on a rotary cutting cylinder.

 The rotary cutting of a cardboard blank is usually carried out by means of rotary cylinders with parallel axes, the external surfaces of which are engraved, and between which the cardboard blank to be cut is pressed. Each of the cylinders is rotatably mounted on bearings held relative to the frame of the cutting machine by bearing boxes whose ends of the axes comprise drive gears. The cylinders used for this type of cutting, the dimensions of which depend on those of the cardboard blank to be cut, are usually of large volume and weight. However, when it is desired to switch from a given product to be cut to a different product, it is necessary to replace the cutting cylinders with other suitable cylinders comprising new engravings. Such replacement of the cutting cylinders involves significant costs, in particular because of the volume of metal to be replaced.

 In order to avoid this drawback, it has been proposed to produce the engraved parts of the cylinders on removable sectors, so as to avoid, during a change of engraving, to change the entire cylinders, which makes it possible to save important matter. However, for such a cutting system to remain effective, it is necessary to adjust the sectors on the cylinders in a particularly precise manner, so that the cost price of such cutting cylinders always remains very high.

 It has also been proposed to carry out the etching on a cylindrical sleeve, which is held at its ends and in its middle part by circular flanges fixed on a core integral with the drive shaft. Sleeves of this type have the disadvantage, despite the large thickness that one is forced to give them, of being deformable under the effect of the significant pressures exerted from one cylinder on the other during of the cutting operation. It has thus been found that these significant efforts have the effect of causing, during rotation, an ovalization of the engraved sleeves, which is detrimental to the quality of the cutting work carried out.

 Another drawback of this type of device is that it makes it necessary to provide, between the flanges which support the sleeve and the internal wall of the latter, games intended for their assembly and which create an inaccuracy in the positioning of the two cutting cylinders one with respect to the other, imprecision which results in a reduction in the quality of the cutting carried out.

 The object of the present invention is to remedy these drawbacks by proposing a device for fixing an engraved sleeve for a rotary cutting cylinder, which ensures positive maintenance of this sleeve over almost its entire internal surface, so that no ovalization cannot occur during operation. In addition, the present device makes it possible to maintain the cutting sleeve relative to the cylinder core which is both free from any operating clearance and easy to remove when it is desired to disassemble the cutting sleeve.

The present invention thus relates to a device for fixing a cutting sleeve for a cutting cylinder rotatably mounted on a drive shaft, characterized in that it comprises
a retaining core secured to the cylinder shaft, the external surface of which comprises at least one frustoconical zone,
a cutting sleeve, the cylindrical external surface of which has a cutting imprint, and the internal surface of which is applied to the external surface of the retaining core, by means of a frustoconical contact surface complementary to the frustoconical surface of the retaining core, and
means for supplying pressurized fluid capable of creating a fluid pressure at the level of said frustoconical contact surface, making it possible to cause a slight temporary deformation of the cutting sleeve, in order to increase the diameter thereof, so as to favor its positioning with respect to the retaining core, these means for supplying fluid can be interrupted to allow fixing by shrinking of the cutting sleeve on the retaining core.

 The fixing device according to the present invention thus makes it possible to use cylindrical cutting sleeves of almost any thickness since said sleeve is held, at all points on its internal surface, by the retaining core, which avoids it any deformation even in the case where, during operation, it is subjected to significant forces on the part of the other cutting cylinder.

 Furthermore, the present invention allows, after use, and by reapplying the fluid pressure, to deform the cutting sleeve, so as to allow the disassembly of the latter and its replacement by a new suitable sleeve.

 In a particularly advantageous embodiment of the invention, the internal surface of the cutting sleeve is cylindrical and the device comprises a fixing element, intended to take place between the cutting sleeve and said retaining core, the external surface of which is cylindrical and of the same diameter as the internal diameter of the cutting sleeve, and the internal surface comprises at least one conical part of the same conicity as that of the external surface of the retaining core, so as to be fixed by hooping on that -this.

 In another embodiment of the invention, the retaining core comprises, at each of its ends, a cylindrical or conical bearing ended by a shoulder which receives a raceway in the form of a crown, this device comprising means to apply and to keep in contact one of the ends of the cutting sleeve against an internal flank of one of the raceways. This embodiment is particularly advantageous in that it makes it possible to index, that is to say to position precisely, the cutting sleeve relative to the retaining core, in the longitudinal direction, that is to say along the direction of the axis xx 'of the cylinders.

 In another embodiment of the invention, the device comprises a wedging element, bearing both on the large base of the fixing element and on the retaining core or on an element integral with that -ci, whose length, that is to say the dimension parallel to the axis xx 'of the cylinders, ensures the longitudinal positioning of the fastening element relative to the retaining core. This embodiment allows a particularly precise positioning of the cutting sleeve relative to the retaining core. I1 also allows, after disassembly, to automatically reposition the cutting sleeve relative to the retaining core in the longitudinal direction.

An embodiment of the present invention will be described below, by way of non-limiting example, with reference to the attached drawing in which
Figure 1 is a schematic view in vertical and longitudinal section of a cutting assembly equipped with a device for immobilizing a sleeve for a rotary cutting cylinder according to the invention.

 Figure 2 is a partial schematic view in longitudinal section of an embodiment of the invention.

 FIG. 3 is a detailed view in longitudinal section of an embodiment of a cutting cylinder according to the invention.

 Figure 4 is a schematic partial cross-sectional view of an alternative embodiment of the invention.

 In FIG. 1, a rotary cutting device consists of two 1.1 'cutting cylinders which are rotatably mounted around longitudinal shafts 3.3' of axis xx ', which respectively engage in rolling bearings 5.5 '.

The shafts 3,3 'are linked together in rotation by two gears in engagement 7,7', so that the cylinders 1,1 'rotate in opposite directions. The shaft 3 comprises a second gear 8 intended to ensure the rotational drive of the entire device.

 The cylinders 1 and 1 ′ have, at each of their ends, cylindrical flanges, or raceways 9, 9 ′ which, in known manner, are in contact with one another so as to maintain a rigorous constant gap between the external surfaces of the two cylinders 1, 1 '.

 The cutting cylinder 1 consists of a retaining core 10, integral with the shaft 3, which has a frustoconical external surface, and of an external cylindrical sleeve 11, or cutting sleeve, consisting of a hardness metal high in which the shape of the cut to be made has been engraved on its external face. The cutting sleeve 11 has a cylindrical external surface, and a frustoconical internal surface of the same conicity as that of the retaining core 10, so that it can be blocked thereon. The periphery of the retaining core 10 is hollowed out by three circular grooves 17 which are in communication by a channel 19 and which can be connected to means for supplying pressurized hydraulic fluid. O-ring seals 21 are arranged at each end of the retaining core 10, in appropriate circular grooves. To ensure the positioning and fixing of the cutting sleeve 11 on the retaining core 10, the pipe 19 is supplied with fluid under pressure, which has the effect of causing a deformation of the cutting sleeve 11 which expands under the effect of the pressure force of the fluid, so that it is then possible to push it back on the frustoconical part of the retaining core 10 on the one hand in order to adjust it to the desired position and on the other hand so ensure its locking by shrinking when the supply of pressurized fluid is removed.

 This ensures that the cutting sleeve 11 is fixed without play to the retaining core 10, which considerably increases the precision of the work carried out for the device.

 Of course, when, after the cutting operation, it is desired to disassemble the cutting sleeve 11 to replace it with a new sleeve, the fluid pressure in the channel 19 is again applied, and the expansion of the cutting sleeve 11 is applied, which occurs under the effect of this pressure, makes it possible to recover the latter.

 In such a method of attachment, the cutting sleeve 11 is held at all points on its surface by the retaining core 10, which allows it to be given a relatively small thickness, without this having any drawbacks in terms of rigidity, as was the case in the interchangeable sleeves of the prior art.

 The present invention thus makes it possible to achieve, compared to the previous solutions mentioned above, quite remarkable gains in material, while retaining good rigidity of the cutting sleeve.

 In an alternative embodiment of the present invention, shown in Figure 2, the cutting sleeve 11 has a cylindrical internal surface whose diameter is such that it allows to introduce between this surface and the external surface of the retaining core 10 a fixing element 15, consisting of a sleeve of cylindrical external surface, of the same diameter as the internal surface of the cutting sleeve 11, and of frustoconical internal surface, of the same conicity as that of the retaining core 10, so that the fixing element 15 can be introduced between the cutting sleeve 11 and the retaining core 10.

 The cutting sleeve 11 is fixed relative to the retaining core 10, as described below. First of all, the fixing element 15 is introduced between the retaining core 10 and the cutting sleeve 11, then the latter is positioned in the longitudinal direction, that is to say along the axis xx 'of the shaft 3 then the pressurized fluid is sent through the pipe 19, which has the effect of causing a deformation of both the fastening element 15 and the cutting sleeve 11, which expand under the effect of the fluid pressure force, so that it is then possible to push the fixing sleeve 15 in an additional amount in the direction of the arrow F. The hydraulic pressure and the assembly consisting of the cutting sleeve are then eliminated 11 and the fixing element 15 then contracts, so that they are fixed on the retaining core 10 by shrinking.

 There is shown in detail in Figure 3 an embodiment of the present invention. In this figure, the cutting element 1 comprises a frustoconical retaining core 10, linked to the drive shaft 3, the small base 12 of which is located on the external part of the cylinder 1 (on the right in FIG. 3), that is to say on the side opposite the rotational drive gears of the cutting sleeve 1.

The retaining core 10 ends, at each of its ends, by a shoulder 23 extended outwards by a cylindrical surface 25 and 31. A first raceway 9a, consisting of a cylindrical ring, is adjusted on the cylindrical surface 25 and is supported on the shoulder 23 to which it is fixed by means of screws 22, regularly distributed over the periphery thereof. The device comprises a cutting sleeve 11 and a fixing sleeve 15, the internal conicity of which is the same as that of the retaining core 10, and which ensures the immobilization of the cutting sleeve 11 relative to the latter. To cooperate effectively, as we know, the etched parts of the two cutting sleeves 11 must be rigorously positioned relative to each other, on the one hand, in the longitudinal direction, and on the other hand, angularly.

 To ensure the longitudinal positioning of the cutting sleeve 11, it is applied against the internal flank of the first raceway 9a, in contact with the shoulder 23, using pressure means which are described below.

 To ensure the angular positioning of the cutting sleeve 11, a hole 26 is produced in the edge thereof, which is fitted onto a key 27 which is fixed by a screw 29 in the thickness of the raceway 9a.

 To secure the shrink sleeve 11 and the fixing element 15 by hooping on the retaining core 10, a series of circular grooves 17 have been provided on the internal face of the fixing element 15 which are in communication, via a pipe 19, produced in the retaining core 10, with a supply of pressurized fluid and in particular a hydraulic fluid, not shown in the drawing. O-ring seals 21 are arranged in circular grooves provided at the ends of the retaining core 10 and are intended to prevent external leakage of the fluid under pressure. One could of course also dig the circular grooves 17 in the retaining core 10.

 The shoulder 23 located on the external side of the core 10 (on the right in the drawing of FIG. 3) is extended towards the outside by a cylindrical bearing 31. This cylindrical bearing 31, receives an intermediate part 32 which includes a central bore adjusting to the cylindrical surface 31, and a frustoconical external face 34, the small base 30 of which is disposed on the external side. This intermediate piece 32 is fixed to the retaining core 10 by means of a series of screws 33, regularly distributed over the periphery of the intermediate piece 32. A second raceway 9b, of external dimensions identical to those of the raceway bearing 9a, and which has a frustoconical internal bore, complementary to that of the intermediate part 32, is fitted thereon, and is held there by a series of fixing screws 35. The raceway 9b comprises, at the level of the fixing element 15, a series of longitudinal cylindrical recesses 37 in which the posterior cylindrical parts of a series of respective adjustment pins 39 fit. Each pin 39 extends from the internal side of the cylinder 1, (left in the drawing), by a base 41, followed by a cylindrical part 43 and a stud 45. An elastic system, for example an O-ring 47, is arranged on the cylindrical part 43, so that its upper part, under the action exerted by the raceway 9b when it is tightened with the screws 35, applies the cutting sleeve 11 against the internal flank of the raceway 9a.

 As shown in FIG. 3, an adjustment ring 49 takes place on the stud 45. This ring 49 is applied by the cylindrical door 43 against the fixing element 15. By varying the thickness, or length of this ring 49 , that is to say on its dimension in the direction of the axis xx ′, the positioning of the fixing element 15 can be adjusted relative to the retaining core 10 and thereby adjust the outside diameter of the cutting sleeve 11.

 It is also possible, as shown in FIG. 4, to replace the one-piece fixing element 15 by a series of segments 15 ′ whose external surface is cylindrical and of the same external diameter as the internal diameter of the cutting sleeve 11, and which are arranged in longitudinal grooves 16 of the retaining core 10 which are inclined relative to the longitudinal axis xx 'of each cylinder.

Claims (12)

 1.- Device for fixing a cutting sleeve for a cutting cylinder rotatably mounted on a drive shaft (3.3 '), characterized in that it comprises  a retaining core (10) integral with the shaft (3.3 ′) of the cylinder, the external surface of which comprises at least one frustoconical zone,  - a cutting sleeve (11), the cylindrical external surface of which comprises a cutting imprint, and the internal surface of which is applied to the external surface of the retaining core (10), via a contact surface frustoconical complementary to the frustoconical surface of the retaining core (10) and,  - means for supplying pressurized fluid capable of creating a fluid pressure at the level of said frustoconical contact surface, making it possible to cause a slight temporary deformation of the cutting sleeve (11), in order to increase the diameter thereof ci, so as to favor its positioning relative to the retaining core (10), these fluid supply means being able to be interrupted to allow fixing by shrinking the cutting sleeve (11) on the retaining core.  2.- Device according to claim 1 characterized in that peripheral housings (17) are provided at said frustoconical contact surface, these housings (17) being in communication with said inlet of pressurized fluid.  3.- Device according to one of claims 1 or 2 characterized in that the internal surface of the cutting sleeve (11) is cylindrical, and the device comprises at least one fixing element (15,15 '), intended to take place between the cutting sleeve (11) and said retaining core (10), the external surface of which is cylindrical and of the same diameter as the internal diameter of the cutting sleeve (11), and the internal surface comprises at least one conical part of the same taper as that of the external surface of the retaining core (10), so as to be fixed by wedging thereon.  4.- Device according to claim 3 characterized in that the fixing element consists of a frustoconical sleeve (15).  5.- Device according to claim 3 characterized in that it comprises a series of fastening elements consisting of segments (15 ') which are arranged regularly on the periphery of the cylinder in longitudinal grooves (16) of the core of holding (10) and which are inclined relative to the longitudinal axis (xx ') of the cylinder.  6.- Device according to one of the preceding claims characterized in that the peripheral housings (17) are hollowed out in the retaining core (10).  7.- Device according to one of claims 1 to 5 characterized in that the peripheral housings (17) are hollowed out in the fixing element (15).  8.- Device according to one of the preceding claims characterized in that the retaining core (10) comprises, at each of its ends, a cylindrical or conical bearing (25) terminated by a shoulder (23) which receives a path bearing (9,9a, 9b) in the form of a crown, this device comprising means for applying and keeping in contact one of the ends of the cutting sleeve (11) against an internal flank of one of the raceways (9a).  9.- Device according to claim 8 characterized in that the application means consist of the other raceway (9b).  10.- Device according to one of claims 8 or 9 characterized in that the application means comprise at least one deformable element (47) disposed between the free end of the cutting sleeve (11) and said other path bearing (9b).  11.- Device according to claim 10 characterized in that it comprises a wedging element (49), bearing both on the large base of the fixing element (15,15 ') and on the core of holding (10), or on an element integral with the latter, the length of which, that is to say the dimension parallel to the axis of rotation (xx '), makes it possible to ensure the longitudinal positioning of the fixing element (15,15 ') relative to the retaining core (10).  12.- Device according to claim 11 characterized in that the wedging element consists of a ring (49) held by a pin (38), parallel to the axis (xx ') of the cylinder (1) which s 'engaged under the internal face of the cutting sleeve (11) and whose length is adjusted to determine the position of the fixing element (15,15') relative to the retaining core (10).