EP0785901B1 - Cartridge and roller for a consumable ribbon, receiving apparatus, and rotational roller coupling method - Google Patents

Abstract

PCT No. PCT/FR95/01340 Sec. 371 Date Feb. 19, 1997 Sec. 102(e) Date Feb. 19, 1997 PCT Filed Oct. 12, 1995 PCT Pub. No. WO96/11872 PCT Pub. Date Apr. 25, 1996A roller for a wound ribbon such as a printer ink ribbon may be rotationally coupled by pushing the projections or teeth of a wheel on a drive spindle into a soft material defining part of the bore in the roller. A spring blade prevents the wheel from freely rotating and provides a snap-in feeling. The roller may be part of a cartridge having members for locking the rollers in a position in which the ribbon tension is optimized. The roller and spindle may be coupled in any relative angular position, and the rollers may thus be locked. Release is automatic when the cartridge is full engaged. The ribbon may therefore be more readily installed in an optimized matter.

Description

The present invention relates to a tape cassette consumable.

The present invention also relates to a roller for winding a ribbon from one of its ends in such a cassette.

The present invention also relates to an apparatus consumer of ribbon, such as a printer, in particular a counter printer.

The present invention also relates to a method for rotationally coupling such a roller with a support mandrel and drive this roller.

The ribbon in question may be an ink ribbon which the machine consumes as it prints documents by a thermal printing process.

Counter printers are called printers editing including tickets, reservation documents and others tickets for passengers on airplanes or others means of transport.

In this type of printer, the ink ribbon is relatively wide and the lines are printed according to the width of the ribbon, and printing is done by lines successive across the width of the ribbon perpendicular to the direction of travel of the ribbon and the document to print. But the invention is by no means limited to this configuration.

Ribbon consuming devices include general two rotary mandrels to support a roll of unwinding the new ribbon and respectively a roll of collection of used ribbon. It is necessary to carry out a rotational coupling between the collecting roller and the corresponding mandrel, which is motor, so that the roller collection is driven in the direction that the ribbon is pulled towards the roller.

In many cases, it is also necessary to ensure a rotary coupling between the unwinding roller and the corresponding mandrel, for example so that the mandrel transmits to the roller a braking torque corresponding to a predetermined tension of the ribbon. It can also be expected, after a first use of all or part of the length of the ribbon, the possibility of rewinding the ribbon on the unwinding roller to carry out a new use of ribbon, which will provide print quality still suitable. To perform such rewinding, the wire feed chuck must also have a motorization in fast reverse.

When installing a new ribbon, the operations are facilitated if the ribbon is contained in a cassette. he it is also possible that the new ribbon and the two rolls are positioned on a charger, made for example in cardboard, which gives the rollers and tape the position precise allowing direct dragging of the assembly in the tape consuming device, by simple translation of the assembly parallel to the axes of the rollers.

But even with these simplifying means, the operator must still perform the rotational coupling between each roll and its core while maintaining the strip along a sufficiently precise route for a region of the ribbon between the two rollers fits between a head and a printing table. However, to achieve the two rotating couplings, it is often necessary to rotate the rollers slightly to find the position in which engagement is possible, and this slight rotation of the rollers can only be done in the sense of relaxation of the ribbon region to be placed between the print head and the print table, which complicates engagement and creates initial conditions for unfavorable operation.

EP-A-0 036 928 describes a device consuming tape whose mandrels have a conical shape to be fitted by friction in the rollers of a cassette.

The object of the invention is to remedy these drawbacks and in particular to allow better engagement of the ribbon new, and to provide improved initial conditions for the use of the ribbon in the ribbon consuming apparatus.

According to the invention, the interchangeable cassette comprising a carcass supporting in rotation two rollers on each from which a ribbon is wound from one of its ends, each roller having an axial bore for be pluggable onto a mandrel of a consumer device ribbon, at least a first of the rollers comprising means in rotation with the corresponding mandrel, is characterized in that the rotating coupling means include a soft material defining at least part of the bore of the first roller, this soft material being intended to be deformed or penetrated by coupling means conjugates belonging to the ribbon consuming apparatus.

By means of coupling by deformation of material tender, as in EP-A-00 36 928, the advantage of no longer need to give the rollers an angular position precise to couple them in rotation relative to the mandrels. But in addition, once the coupling is achieved, the deformation soft material creates a mechanically reliable coupling. The soft material of the rollers is capable of ensuring coupling with a wide variety of means provided on the chucks. It may in particular be projections or a or several claws which deform the soft material or penetrate the tender material sufficiently that the rotation coupling is reliable.

The soft material may for example consist of cardboard or in a flexible plastic material which may be an elastomer. The coupling means are thus very economical to produce and several types of rollers can be accepted by one same mandrel.

It is advantageous for the cassette to include means disengageable to prevent each roller from turning in the sense of tape relaxation.

Before mounting the cassette, these means maintain the two rollers in a position where the ribbon is stretched in the region where he must position himself in relation to a position of use, i.e. for example between a head and a printing table. Thanks to the means of coupling according to the invention, requiring no position predetermined rollers relative to the mandrels, placing in place of the cassette can be done optimally, after which we disengage the disengageable means to allow the rollers spin under the action of the mandrels.

This declutching can be ensured automatically at the end inserting the cassette, for example by means of a member provided on the device and actuating the disengageable means at the end of the cassette insertion.

According to a second aspect of the invention, the roller for a cassette according to the first aspect, provided with a bore and comprising a relatively rigid tube and means for rotational coupling with a drive mandrel belonging to a device capable of receiving the cassette, is characterized in that the coupling means in rotation include a soft material attached to the tube and defining a at least part of the roller bore.

According to a third aspect of the invention, the apparatus ribbon consumer, comprising two cores, one of which less is motor, to receive two unwinding rolls and respectively to collect the ribbon consumed by the device, the motor chuck comprising means for rotationally coupling with the corresponding roller, is characterized in that the coupling means include claw means designed to locally deform or penetrate a soft material defining at least part of the bore of the corresponding roller, whatever the angular position in which said corresponding roller is engaged on the motor chuck.

The invention also relates to the combination of an apparatus according to the third aspect and a cassette according to the first aspect.

According to a fourth aspect of the invention, the method for mount two rollers, each supporting one end of a ribbon, in a device consuming this ribbon, in engaging two mandrels of the apparatus each in a bore center of one of the rollers while coupling in rotation at least one of the rolls of ribbon with one corresponding chucks, is characterized in that by the fitting is made to penetrate a projection provided on the mandrel in a soft material defining at least one part of the roller bore.

Preferably, by fitting the roller onto the mandrel, a rotating mounted coupling member is rotated on the mandrel and comprising at least two projections successive of which one is pushed by the leading edge of the roller, as a result of which the other protrudes, initially erased, in turn comes to interfere with the roller penetrating into the tender material constituting at least one part of the roller bore.

Other features and advantages of the invention will emerge further from the description below, relating to non-limiting examples.

• la figure 1 est une vue schématique en perspective montrant une cassette conforme à l'invention prête à être mise en place dans une imprimante conforme à l'invention, représentée avec arrachements.
• la figure 2 est une vue en perspective de la cassette de la figure 1 ;
• la figure 3 est une vue en perspective partielle de l'un des mandrins ;
• la figure 4 est une vue en élévation de l'un des mandrins de l'imprimante, avec coupe partielle de la cassette installée dessus ;
• les figures 5 et 6 sont des vues de détail illustrant le procédé selon l'invention, pendant l'opération de couplage entre le rouleau de ruban et le mandrin, et respectivement à l'issue de cette opération ;
• la figure 7 est une vue de face, schématique et partielle, de la cassette, visualisant les moyens de verrouillage débrayables des rouleaux ;
• la figure 8 est une vue en perspective éclatée d'un deuxième mode de réalisation de la cassette ; et
• la figure 9 est une vue analogue à la figure 1 et illustrant la mise en place d'un ruban neuf à l'aide d'un chargeur jetable.

In the accompanying drawings:

• Figure 1 is a schematic perspective view showing a cassette according to the invention ready to be placed in a printer according to the invention, shown with cutaway.
• Figure 2 is a perspective view of the cassette of Figure 1;
• Figure 3 is a partial perspective view of one of the mandrels;
• Figure 4 is an elevational view of one of the mandrels of the printer, with partial section of the cassette installed thereon;
• Figures 5 and 6 are detailed views illustrating the method according to the invention, during the coupling operation between the ribbon roll and the mandrel, and respectively at the end of this operation;
• Figure 7 is a schematic and partial front view of the cassette, showing the disengageable locking means of the rollers;
• Figure 8 is an exploded perspective view of a second embodiment of the cassette; and
• Figure 9 is a view similar to Figure 1 and illustrating the establishment of a new ribbon using a disposable charger.

In the example shown in Figure 1, the printer 1 includes in a housing 2, two mandrels 3 supported in rotation in the housing 2 along axes of rotation parallel. Each mandrel 3 is intended to be fitted in two tubular rollers 4 supported in rotation according to parallel axes in the carcass 6 of a cassette 7 which can be mounted interchangeably in box 2 of the printer 1. In the carcass 6, an ink ribbon 8 is wrapped from a first end on one of the rollers 4 and from the other end on the other roll 4. From each roll 4, the ribbon 8 follows a path 9 to the end of a respective nozzle 11 defined by the carcass 6. Between the two nozzles 11, a region 12 of the ribbon 8 is exposed for use. Printer 1 includes in addition to a print head 13 which, when the cassette, engages in a space 14 between the exposed region 12 of the tape 8 and a closure wall 16 which has the carcass 6 facing region 12.

A printing table 17 located in front of the head 13, and different guides 18, define a path for paper 19 or other medium to be subjected the impression. When the cassette 7 is placed, the region exposed 12 of the ribbon 8 is placed between the path for the paper 19 and the print head 13, as illustrated by the mixed line 12a, one of the spouts taking position 11a.

In Figure 2, the cassette is more visible detailed and on the opposite side to that shown in Figure 1. The cassette comprises two flanges 21 fixed to each other by side half-walls 22 which release two windows 23. These allow, without exceeding the bulk maximum available in the printer, wind up more tape on each roll 4. The autonomy of use of the cassette is increased. At the end of each nozzle is mounted a rotary cylinder 24 which allows to guide the ribbon 8 without deterioration.

The front face of the cassette 7 includes a grip 26 to facilitate the extraction of the cassette when its ribbon 8 is used.

In FIG. 4, the carcass 6 is only shown in the upper half of the figure. Each roll 4 includes at its end before thinning limited by a shoulder 27 which abuts against the inner face of the flange 23 adjacent. At its rear end, each roller 4 comprises a locking toothed wheel 28 whose function will be exposed later and which abuts against the inner face on the other flange 23. Thus, the rollers 4 are trapped between the two flanges 23 against any displacement axial with respect to the carcass 6, with the exception of a set of operation.

As shown in Figures 4, 5 and 6, each roller 4 has a cylindrical axial bore 29 defined on the most of its length by a material tube substantially rigid plastic 31. The tube 31 defines also the entire outer surface of the roller 4 as well as, in one piece, the locking disc 28. A its rear end turned in service towards the inside of the case 2 of the printer, the tube 31 has a clearance interior 32 in which is fixedly fitted a ring in soft material 33. The radially inner face 34 of the ring 33 is cylindrical and forms the rear end of bore 29. The soft material of ring 33 can be consisting of a soft or flexible plastic, or by an elastomer.

Each mandrel 3 has an outer surface cylindrical 36 over a certain length from a tapered free end 37, and a rear shoulder 38 which limits the penetration of the rollers 4. Recesses 39 separated by axial stiffening ribs 41 and 42 extend between the shoulder 38 and the outer wall cylindrical 36. The ribs 41 and 42 have edges radially outer which extend the cylindrical surface 36 to ensure the centering of the rear region of the roller 4. The two ribs 41, diametrically opposite and located at angular mid-distance between the two ribs 42, have in in addition to a support function for coupling means 43 angular with the roller 4. Each rib 41 has at a short distance from the shoulder 38 a notch 50 in its radially outer edge 44. The notch 50 is formed between a recess 46 on the side of the rear shoulder 38, and two successive recesses 47 and 48 on the other side. The recesses 47 and 48 are separated by a surface 49 forming a fixing plate for a fixed part of a blade spring 51. The free end 52 of the blade 51 points towards the offset 46. A caster 53 is freely mounted pivoting on one of the lateral faces of each rib 41, along an axis 54 having a tangential orientation by relative to the axis 56 of the mandrel, very close to the shoulder 38. Roulette 53 has sharp teeth 57 regularly distributed around its periphery so that some of them (57b and 57c in Figure 5) protrude into notch 50 between recesses 46 and 47, and others (57a for example, in Figure 5) protrude radially outward relative to edge 44 and more generally relative to the cylinder defined by the surface 36 of the mandrel 3. The free end 52 of the spring 51 interferes with the path of the teeth 57 in the notch 50.

We will now explain how the means work described so far, this description including that of method according to the invention.

As shown in Figure 5, regardless of the position angle of the wheel 53, there is always a tooth 57a which protrudes beyond edge 44 and that is the first encountered by the leading edge of roller 4 being fitted on the mandrel 3. This tooth 57a will serve as a stop for the rotary coupling operation. In effect, when the roller 4 is pushed further to the left from the position shown in figure 5, to finish to put it in place, the leading edge of the roller 4 pushes the tooth 57a, which causes the wheel 53 to rotate and therefore the penetration of the next tooth 57b into the soft material of ring 33 and even, as shown in the Figure 6, the next tooth 57c. These teeth constitute claws which penetrate into the soft material of the ring 33 to ensure then, when the roller 4 is in place (Figure 6) a rotational coupling between the roller 4 and the mandrel 3 around the axis 56.

When roulette 53 spins as stated above high under the thrust of roller 4 being engaged, a click occurs every time a tooth 57 crosses the free end 52 of the leaf spring 51, with bending then relaxation of the latter. These clicks give a feeling of engagement for the person putting in place The tape.

Once roller 4 is in the service position on the mandrel 3 (figure 6) there is a tooth 57d which projects in the notch 50 and which abuts against the free end of the blade 51 on the side preventing easy rotation of the wheel 53 in the direction corresponding to the release of the roller 4 relative to the mandrel 3 and to the movement of teeth 57c then 57b radially inward. So the cassette is firmly held in place in the position where the tape 8 has an optimal path relative to the head printing. When all the tape 8 of the cassette has been consumed, the removal of the cassette will be accompanied again at least one click, this time corresponding to disengage.

As shown in Figure 7, the locking means disengageable include in addition the toothed discs 28 (one per roller), two pawls 58 each cooperating with the teeth of one of the discs 28 to prevent rotation of the roller 4 corresponding to the relaxation of the exposed region 12 of the ribbon 8. The two pawls 58 are opposite one another. the other and made in a single leaf spring with a actuation region 59 which brings them together. From either side of region 59, the blade has a bend 61 and a counter bend 62 in a region where it passes between two bosses 63 and 64 from the carcass. Each elbow 61 and counter elbow 62 defines a shoulder 66. The two bosses 63, located between the two shoulders 66, prevent the spring leaf from follow a joint movement of the two discs 28 in a one way or the other, and therefore prevent the rollers 4 from both turn in the same direction. So when the two pawls are in the active position shown in solid line in Figure 7, each roller 4 cannot rotate that in one direction, contrary to that allowed with the other roller 4 (see arrows F), and corresponding to an increase in the tension of the exposed region 12 of the ribbon 8.

When manufacturing the cassette, a voltage is given to ribbon 8 and in particular to its exposed region 12, and this tension is maintained during the transport, storage and installation of the cassette thanks to the disengageable locking means, which remain active throughout this period.

However, the actuation region 59 is placed in look of an orifice 67 of the rear flange of the carcass. When installing the cassette (Figure 1), a body actuator 68 of the printer engages in orifice 67 and moves the actuation region 59 (FIG. 7) to the position shown in phantom. Each couple of bosses 63, 64 then forms a pivot and the pawls 58 take the withdrawal position also shown in mixed line, in which they are released from the teeth of discs 28. The rollers 4 are then free to rotate in the same sense as is necessary for one to collect the used ribbon while the other unwinds the ribbon still not used. For this, one of the mandrels 3, receiving the roller of collection, is connected to a drive motor while the other, receiving the unwinding roll, is connected to a braking system ensuring a certain tension of the exposed region 12 of ribbon 8 during printing. The couple and the braking torque are transmitted by the rotational coupling means 33, 53 which have been described more high.

In the embodiment shown in Figure 8, which does not will be described only for its differences with that of FIGS. 1 to 7, the cassette is produced more economically by two end flanges 71 connected to each other by rods spacers 72 forming a cage. The two guide cylinders 24 are trapped between the flanges 71 through rings 73 forming a bearing. Rollers 74 are fully made of soft material 75, these are simple tubes made of cardboard. In particular, the carton 75 defines the bore 29 of the rollers 74. For their mounting in rotation in the flanges 71, these each have two circular lights 76 in each of which is fitted with a plastic ring 77 having a certain axial length, to limit the coefficient of friction and pressure experienced by each roller 74 at each of its ends during its rotation.

When placing this cassette, it is the end of the cardboard roller which causes the roller 53 to rotate Figures 3 to 6, thus causing the penetration of teeth such as 57b and 57c, not in a ring 33 specially provided for this purpose as in Figure 6, but in the box constituting the entire roll 74.

For the sake of simplification, no means are provided disengageable locking mechanism to keep the ribbon in tension until the cassette is placed in the printer.

In the example shown in Figure 9, the device according to the invention, and the method according to the invention, are implemented even more economically, no longer with a cassette but simply with two pre-positioned cardboard rolls 84 on a disposable charger 86 also made of cardboard and which comprises different walls parallel to the axis of the rollers 84. These walls position the two rollers 84 along an axis corresponding to that of the mandrels 3, and position the regions 9 and 12 of the ribbon 8 in accordance with the planned route for them in printer 1. A plastic strapping 87 ensures the cohesion of the whole.

To renew the ribbon 8 in the printer 1, after having removed the ribbon and the used rollers, we engage the feeder into printer 1 with mandrel fitting 3 in the cardboard rollers 84. The coupling is caused by rotation thanks to the casters 53 as said about of Figure 8, the teeth of the caster entering the cardboard rollers 84. Then remove the hoop 87 at by means of one or more tabs 88 which allow tear the strapping 87 along one or more lines attenuation 89 provided for during manufacture. We can then remove the cardboard magazine 86 and discard it (or save the box for recycling).

We understand that thanks to the invention the same printer can receive very different refills others, provided the rollers have a soft part suitably located.

Of course, the invention is not limited to the examples described and represented.

Rather than being carried out by claws, the coupling in rotation could be achieved by splines or the like protrusions capable of deforming the soft material, but without the pierce with claws.

The invention is applicable to all devices consuming ribbon. In the field of printers, it is not limited to counter printers.

Claims (25)

1. Interchangeable cartridge comprising a casing (6) rotationally supporting two rollers (4, 74) onto each of which a ribbon (8) is wound from one of its ends, each roller including an axial bore (29) so that it can be slid onto a spindle (3) of a ribbon-consuming apparatus, at least a first one of the rollers including means (33, 75) for rotational coupling with the corresponding spindle (3), characterized in that the rotational coupling means comprise a soft material (33, 75) defining at least part of the bore (29) of the first roller (4, 74), said soft material being intended to be deformed or penetrated by conjugated coupling means belonging to the ribbon-consuming apparatus.
2. Cartridge according to claim 1, characterized in that it contains disengageable means (28, 58) in order to prevent each roller (4) from turning in the direction of release of the ribbon (8).
3. Cartridge according to claim 2, characterized in that the disengageable means comprise, in the case of each roller, a pawl (58) interacting with a toothed wheel (28) integral with the roller (4), the two pawls (58) having an actuation region (59) which is exposed to the action of an actuating member (68) provided in the receiving apparatus (1).
4. Cartridge according to claim 3, characterized in that the two pawls (58) are produced opposite one another on either side of the actuation region (59) which is common to the two pawls and connects them to each other.
5. Cartridge according to claim 4, characterized in that the two pawls (58) and the actuation region (59) are made up of a single spring blade which is supported in the casing in two positions (63, 64) which form pivoting axes and are situated on either side of the actuation region (59).
6. Cartridge according to one of claims 1 to 5, characterized in that the soft material (33) is a flexible, synthetic material.
7. Cartridge according to one of claims 1 to 6, characterized in that the roller (4) contains a ring made of soft material (33) and fitted into a more rigid outer tube (31).
8. Cartridge according to one of claims 1 to 5, characterized in that the soft material is cardboard (75).
9. Cartridge according to claim 8, wherein each end of the roll is rotatably supported with respect to the casing, characterized in that at at least one of the ends of the roller a region of the roller (74) made of cardboard is rotationally supported in a ring made of plastic (77) slid into a plate (71) of the cartridge.
10. Cartridge according to claim 8 or 9, characterized in that the roller (4) is made of cardboard (75).
11. Roller for a cartridge according to one of claims 1 to 9, equipped with an axial bore (29) and comprising a tube (31) made of relatively rigid material and means (33) for rotational coupling with a support spindle (3) belonging to an apparatus (1) capable of receiving the cartridge, characterized in that the rotational coupling means comprise a soft material (33) which is fixed to the tube (31) and defines at least part of the bore (29) of the roller.
12. Roller according to claim 11, characterized in that the soft material (33) is located at one end of the bore.
13. Roller according to claim 11, charaterized in that the soft material is in the form of a ring (33) slid onto the relatively rigid tube (31).
14. Ribbon-consuming apparatus, comprising two spindles (3) at least one of which is a motor spindle, in order to receive two rollers (4; 74; 84) respectively for unwinding and for taking up the ribbon consumed by the apparatus, the motor spindle having means (53) for rotational coupling with the corresponding roller (4; 74; 84), charaterized in that the coupling means (53) comprise clawing means which are designed in order locally to deform or penetrate a soft material defining at least a portion of the bore of the corresponding roller (4; 74; 84) irrespective of the angular position in which the corresponding roller is engaged on the motor spindle (3).
15. Apparatus according to claim 14, characterized in that it is designed in order to receive a cartridge (7) rotationally supporting the two rollers (4), and in that it contains a member (68) capable, during engagement of the cartridge, of actuating disengageable means (28, 58) in the direction of disengagement, which means are provided on the cartridge, in order selectively to prevent the rollers (4) from turning in the direction of release of the ribbon (8).
16. Apparatus according to claim 14 or 15, characterized in that the coupling means (53) are set back relative to one free end (37) of the spindle and project radially relative to a centring surface (36) belonging to the spindle (3).
17. Apparatus according to claim 16, characterized in that the coupling means (53) are situated in the vicinity of a rear end of the spindle (3).
18. Apparatus according to one of claims 14 to 17, characterized in that the clawing means comprise a toothed wheel (53) fitted in rotation along a substantially tangential axis (54) of the spindle (3) in such a way that, in any angular position of the wheel before insertion of a ribbon roller (4; 74; 84), at least a first tooth (57a) of the wheel is in the position of a mobile means capable of being pushed by a roller (4; 74; 84) being inserted, and that another tooth (57b, 57c) is in claw position which, by rotation of the wheel (53), will penetrate the material (33, 75) of the roller (4; 74; 84) when the latter pushes the first tooth.
19. Apparatus according to claim 18, characterized by a spring blade (51) which is fixed to the spindle (3) and one free end (52) of which interferes with the teeth (57) of the wheel (53).
20. Apparatus according to one of claims 14 to 18, characterized by means (51) for slowing down the claw (57b, 57c) at least against its movement radially towards the interior.
21. Apparatus according to one of claims 14 to 18, characterized in that the coupling means (53) are designed in order to produce a ratchet motion of the roller (4; 74; 84) onto the motor spindle (3), by crossing a hard point when the roller is slid onto the motor spindle.
22. Apparatus according to one of claims 14 to 21, characterized in that the apparatus is a printer (1) consuming ink ribbon (8).
23. Combination of an apparatus (1) according to one of claims 14 to 22 and a cartridge (7) according to one of claims 1 to 10.
24. Method of fitting two rollers, each supporting one of the ends of a ribbon (8), into an apparatus (1) consuming this ribbon, by sliding two spindles of the apparatus each into a central bore (29) of one of the rollers while rotationally coupling at least one of the rollers (4; 74; 84) of ribbon (8) with the corresponding spindle roller (3), characterized in that, by sliding them in, a projection (57b, 57c) provided on the spindle (3) is made to penetrate a soft material (33) defining at least part of the bore (29) of the roller (4; 74; 84).
25. Method according to claim 24, characterized in that, by sliding the roller (4; 74; 84) onto the said corresponding spindle (3), a toothed coupling wheel (53) is made to pivot, which wheel is fitted so as to rotate on the spindle and has at least two successive teeth (57a, 57b) one of which (57a) is pushed by the leading edge of the roller, as a result of which the other tooth (57b), initially unused, in its turn interferes with the roller (4; 74; 84), penetrating the soft material (33) constituting at least part of the bore (29) of the roller (4; 74; 84).

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