Blade-holder device, cutting or perforating device comprising the blade-holder device, and machine

Abstract

The blade-holder device comprises a support extending in a longitudinal direction. On the support at least one seat for a blade is provided, the seat extending in the longitudinal direction along the support. The seat is configured to receive and retain a blade oriented with its cutting edge extending in the longitudinal support direction. The device further comprises at least one locking clamp constrained to the support with a wedge system for locking the blade.

Description

BLADE-HOLDER DEVICE, CUTTING OR PERFORATING DEVICE COMPRISING THE BLADE-HOLDER DEVICE, AND MACHINEDESCRIPTIONTECHNICAL FIELD

[0001] The present invention relates to machines and devices for processing web materials, such as for example (but not exclusively) webs of cellulosic material such as paper, tissue paper, layers of non-woven fabric, plastic film and the like.BACKGROUND ART

[0002] In many industrial sectors the need exists to carry out cuts or perforations on web materials which are continuously supplied along a supply path. For example, in the field for processing paper tissue, for producing toilet paper rolls, paper towel and similar products, there arises the need to provide perforation lines on a single- or multilayer paper web continuously supplied towards a rewinder. To produce cellulosic products made of sheet, the need arises to cut a continuous web material into single sheets which are then supplied to a converting machine, for example an interfolding machine.

[0003] Cuts and perforations are carried out with special devices, which have a rotary blade-holder, on which one or more cutting or perforating blades are arranged, cooperating with a stationary blade (also generally referred to as “anvil-blade”), usually supported on a stationary, i.e., non-rotating, blade-holder device.

[0004] US5, 125,302 discloses a perforating device for rewinders, wherein a plurality of straight blades are carried by a rotary roller or blade holder and cooperate with a helical stationary blade (anvil blade).

[0005] In some paper converting machines, especially tissue paper converting machines, blade devices are provided for cutting web material into single sheets, separated from each other, rather than joined along perforation and tear-off lines. For example, cutting devices with rotary blades and stationary anvil blades are used in interfolding machines to produce folded and interfolded sheet packs. In certain embodiments of these machines cutting is carried out with a rotary blade-holder which supports a plurality of blades with constant pitch, which cooperate with a stationary anvilblade. Cutting units of this type, in the context of interfolding machines, are disclosed for example in EP2379435B1, EP2502738B1.

[0006] Cutting devices similar to those in the paper converting industry, but smaller in size, are also used in the packaging industry, in particular for machines that package products made by the paper converting lines. These packaging machines wrap a group of products using a packaging sheet obtained starting from a continuous plastic or paper web unwound from a reel. This continuous web needs to be cut transversely into individual sheets. To this end, cutting units are used, consisting of a rotary blade holder that supports one or more blades, co-operating with a stationary blade or anvil blade carried by a stationary blade-holder device. The blades of the rotary blade holder, cooperating with the stationary anvil blade, can carry out a scissor cut, i.e., where the contact point between the blade and anvil blade moves from one end to the other of the cutting edges of the blades and anvil blade. To this end, the rotary blades or the anvil blade have a helical shape. A cutting unit for packaging machines is for example disclosed in EP 1052209.

[0007] The continuous interaction between rotary blades and stationary blades (anvil blades) causes wear and may also cause breakage of the blades. Therefore, a need exists, to provide systems that allow for the safe mounting of stationary and movable blades, but also for their easy removal for replacement or adjustment in order to recover wear.

[0008] Various systems for fitting and locking fixed or rotary blades in the cutting or perforating devices are known. A particularly efficient system for locking the blades of a perforating or a cutting device is disclosed in WO2023 / 232895. This prior art device is an improvement with respect to other prior art devices but can be further improved, for example to be more compact, or more efficient in tightening the blade.SUMMARY

[0009] According to an aspect, herein described is a blade-holder device for a blade for cutting or a blade for perforating a web material which fully or partly overcomes the drawbacks of the prior art.

[0010] The device comprises a support extending in a longitudinal direction. At leastone seat for a blade is provided on the support , the seat extending in the longitudinal direction along the support. The seat is configured to receive and retain a blade oriented with the cutting edge thereof extending in the longitudinal support direction. The blade may be straight or helical, for example. The device further comprises at least one locking clamp constrained to the support.

[0011] The blade can be single-block, consisting of a single element, or it may comprise a plurality of portions aligned to each other.

[0012] Depending on the length of the blade, the device may comprise a plurality of locking clamps aligned with each other along the seat for the blade.

[0013] The device further comprises an elastic member constrained to the support and configured to push the locking clamp towards the seat for the blade and generate a clamping force on the blade positioned in the seat. A wedge-shaped element is arranged between the elastic member and an inclined surface of the locking clamp. The wedge-shaped element has a variable thickness along a sliding direction, and the locking clamp is movable along the sliding direction with respect to the support. The elastic member is arranged to press the wedge-shaped element against the inclined surface of the locking clamp. The movement of the locking clamp in the sliding direction causes a sliding of the inclined surface of the locking clamp along the wedge-shaped element and a resulting tightening and release the locking clamp with respect to the seat for the blade.

[0014] In advantageous embodiments, each clamp may comprise a greater number of elastic members and respective inclined surfaces and wedge-shaped elements, which acts simultaneously on the clamp, as will be described below with reference to a non-limiting embodiment. For example, two, three, four or more wedge-shaped elements and respective elastic members may be provided for a single clamp.

[0015] In advantageous embodiments, the sliding direction is oriented according to the longitudinal support direction and therefore substantially parallel to the cutting edge of the blade. However, the possibility of configuring the device so that the sliding direction is orthogonal to the cutting edge of the blade cannot be ruled out.

[0016] In certain embodiments, the elastic member may be constrained to the supportthrough a pin that passes through the locking clamp and the wedge-shaped element and it is fixed to the support. This allows to obtain a particularly compact and efficient configuration.

[0017] For example, the elastic member may be positioned so as to surround the pin. It may consist of one or more Belleville washers, a compression helical spring or multiple helical springs, one or more annular elastic bodies, for example made of polymeric material, or other. The type of elastic member may may be selected for example also as a function of the force required for clamping the blade.

[0018] For example, the pin may have a first end fixed to the support and a second end forming a head which retains the elastic member and the wedge-shaped element on the support. The elastic member may be arranged between the head of the pin and the wedge-shaped element. The first end of the pin may be threaded and screwed into a threaded hole, such as for example a threaded blind hole, made in the blade support.

[0019] In order to obtain a particularly compact embodiment, the wedge-shaped element may be housed in a seat formed in the locking clamp and having a bottom forming an inclined surface of the locking clamp. For example, the seat may be slot-shaped, that is it can be elongated, for example in the sliding direction.

[0020] If a fixing pin is provided, said pin may pass through the bottom of the seat.

[0021] In advantageous embodiments, the locking clamp comprises a seat for an operating tool, the seat being superimposed to a through hole in the locking clamp for introducing a stem of the operating tool. For example, the seat for the operating tool may comprise two substantially flat surfaces which are parallel and opposite to each other and extending transversely to the sliding direction.

[0022] The support may comprise a sliding seat, wherein the locking clamp is guided in a sliding manner, for a more controlled movement of the clamp. For example, the sliding seat is arranged side by side and adjacent to the seat for the blade, and the locking clamp may comprise a protrusion housed in the sliding seat and a lateral projection forming a pressure surface adapted to press on the blade housed in the seat for the blade. When a sliding seat and a pin which constrains the elastic member to the support are provided, the pin may be fixed in the sliding seat.

[0023] According to a further aspect, a cutting or perforating device is provided, comprising a rotary blade-holder device for at least one rotary blade and a stationary blade-holder device for a stationary blade cooperating with a rotary blade, wherein at least one of said rotary blade-holder and said stationary blade-holder device is configured as described above.

[0024] Further advantageous features and embodiments of the support outlined above are described below and defined in the attached claims.

[0025] According to a further aspect, herein a cutting or perforating device is provided, comprising a rotary blade-holder device for at least one rotary blade and a stationary blade-holder device for a stationary blade cooperating with a rotary blade. Characteristically, at least one of said rotary blade-holder device and said stationary device is a blade support device as defined above.

[0026] Advantageously, the stationary blade and the rotary blade are arranged for carrying out a scissor cutting. To this end, one of said stationary blade and the rotary blade has a helical shape and the other preferably has a straight shape, in order to carry out a scissor cut.

[0027] According to still a further aspect, a machine for processing a continuous web material is provided, comprising a path for supplying the web material and a cutting or perforating device as defined above.BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The invention will be clearer from the description and the attached drawings, which illustrate an embodiment provided by way of non-limiting example of the invention. More particularly, in the drawings:Fig.l is a schematic of a rewinding machine with a perforating unit which may comprise a blade-holder device according to the present disclosure;Fig.2 is a schematic of an interfolding machine with two cutting units which may comprise a blade-holder device according to the present disclosure;Fig.3 is a top view, according to line III-III of Fig.4, of a locking clamp;Fig.4 is a cross-section according to IV-IV of Fig.3;Fig.5 is an enlargement of a detail of the locking clamp in the section of Fig.3,in the locked blade position;Fig.6 is a cross-section according to VI- VI of Fig.5;Fig.7 is a section similar to Fig.5 with the locking clamp in the vacant blade position;Fig.8 is a section according to line VIII- VIII of Fig.7; andFig.9 is a section according to line IX-IX of Figs.3 and 4.DETAILED DESCRIPTION

[0029] Fig.l schematically shows a rewinder 1 provided with a perforating unit 3. The rewinder 1 is shown by way of example of a generic machine for converting or transforming a continuous web material N. The structure of the rewinder 1 is shown purely by way of example and may vary in a manner known to persons skilled in the art.

[0030] Generally, the rewinder 1 may be a peripheral rewinder, preferably an automatic and continuous peripheral rewinder, that is, capable of producing automatically and without downtime, in rapid sequence rolls R of wound web material N.

[0031] The rewinder 1 may comprise a winding head 5 provided with a plurality of motor-driven winding rollers 7, 9, 11, 13 and other members known to those skilled in the art. Embodiments of rewinding machines are disclosed for example in EP2621844, EP0694020, EP2655227. In other embodiments, not shown, the rewinder may be a central rewinder, i.e., a rewinder in which the winding motion is imparted to the rolls from the centre of a spindle or winding core. In yet further embodiments, the rewinder machine may be a combined peripheral and central rewinding machine, in which the winding motion is transmitted partly by contact friction between the outer surface of the roll being formed and peripheral rewinding members (such as rollers or belts) and partly through a pair of drive centers or other members that engage the roll axially.

[0032] Although in the present context the perforating unit 3 is described combined with a rewinder 1, which produces rolls of wound material, in other embodiments the perforating unit 3 may be combined with one or more machines for processing a web material to produce different articles. For example, the perforating unit 3 may be associated with a machine for producing packages formed from a continuous web material that is perforated and zig-zag folded.

[0033] The perforating unit 3 comprises a rotary blade-holder device for a plurality of rotary blades. Hereinafter, the rotary blade-holder device will be referred to as the rotary “blade-holder” and is indicated with 15. The rotary blade-holder 15 is supported on a load-bearing structure 17, for example comprising two opposite sides 17 between which the blade holder 15 is arranged. The blade holder 15 rotates around a rotation axis A-A. The blade holder 15 is provided with a set of perforating blade assembly. Generally speaking, the set of perforating blade assembly may also comprise a single perforating blade. In preferred embodiments, the blade holder 15 is provided with a plurality of perforating blades. In the illustrated example, the blade holder 15 is provided with four perforating blades 19, preferably spaced apart by the same angular pitch around the rotation axis A-A of the rotary blade-holder 15. However, a blade holder may also be provided having a larger number of blades A larger number of blades, for example six or eight blades.

[0034] In the illustrated embodiment, the perforating unit 3 comprises a second rotary blade-holder 15B, which is provided with a second rotary blade assembly 19B. The two rotary blade-holders 15, 15B may be used alternatively, possibly depending on the type of product to be produced, by feeding the web material N to be perforated through the one or the other of alternative paths, indicated in Fig.l with solid and dashed lines, respectively.

[0035] The perforating unit 3 further comprises a stationary blade, hereinafter referred to as “anvil blade” 21 carried by the support structure 17 and extending, similarly to the blade-holder 15, between two sides and supported by them. The anvil blade 21 is preferably fixed or stationary with respect to the support structure 17. As understood herein, the expression “fixed” or “stationary” is used to indicate that the anvil blade does not contribute to the rotation motion that generates the perforations of the web material N. This does not rule out that the anvil blade be provided with some movement. For example, the anvil blade 21 may be provided with a reciprocating translation motion parallel to the longitudinal extension thereof, in order to avoid the concentration of wear due to the serrated shape of the perforating blades 19. The anvil blade 21 may be provided with a translation and / or rotation movement so as to carry out an adjustment, and / or to select one or the other of multiple anvil blades present in the perforating unit 3, as better detailed below.

[0036] In order to obtain perforation lines, rather than complete cutting of the web material, the perforating blades 19, or the anvil blade 21, have a serrated, i.e., discontinuous, cutting edge with notches at which the web material remains intact, i.e., it is not cut, forming continuity points of the web material.

[0037] In the illustrated embodiment, the anvil blade 21 is carried by a stationary, i.e., non-rotating, blade-holder device, hereinafter referred to as “beam” and indicated with 22. The beam 22 extends in a direction approximately parallel to the rotation axis A-A of the blade-holder 15. In certain embodiments, as shown in the attached drawing, further additional anvil blades indicated with 2 IB, 21C may be provided, for example carried by the beam 22. The latter may be adjusted in an angular position with a step-by-step movement around an axis B-B, so as to position selectively one or another anvil blade 21, 2 IB, 21C in an operative position.

[0038] If the perforating unit 3 comprises two rotary blade-holders 15, 15B, this allows to alternatively use one or the other of the anvil blades 21, 2 IB, 21C in combination with the rotary blades 19 or 19B of the blade-holder 15 or of the blade holder 15B, selectively.

[0039] The presence of multiple stationary blades, i.e., perforation anvil blades 21, 2 IB, 21C may be useful for example to rapidly replace one worn out anvil blade with another anvil blade. In certain embodiments, the anvil blades 21, 2 IB, 21C may have different characteristics, for example serrations different from each other so as to allow to change the type of production, when this change also requires the change of the type of perforations.

[0040] The beam 22 may be supported on the sides of the load-bearing structure 17 by eccentric supports, so that a small rotation of the beam 22 approaches or moves away the blade 21, 2 IB, 21C adjusting the interference between the rotary blades 19 and the anvil blade 21, 2 IB, 21C.

[0041] The web material N is supplied along a path which extends between the rotary blade-holder 15 and the anvil blade 21, so as to be subjected to the action of the rotary blades 19 and of the anvil blade 21.

[0042] In order to obtain a gradual perforation action through the width of the webmaterial N, the anvil blade 21 may be helical and the blades 19 may be rectilinear, i.e., they may be arranged parallel to the rotation axis A-A of the blade holder 15. The anvil blade 21 is helical in the sense that the cutting edge thereof extends according to a helical line, arranged on an ideal cylindrical surface coaxial to the rotation axis A-A of the blade holder 15. A perforating unit 3 with a helical anvil blade and straight rotary perforating blades is disclosed in US 5,125,302.

[0043] In other embodiments, the arrangement is reverse, in the sense that the perforating blades 19 are helical, while the anvil blade is straight. In this case, the perforating blades 19 are helical in the sense that their cutting edges may extend each along to a helical line lying on a cylindrical surface coaxial to the rotation axis A-A of the blade holder 15.

[0044] What has been described above in relation to Fig.1 has the purpose of showing the context in which a cutting or perforating device according to the present invention may be inserted. The details of the device, which can be used also in machines of another type, will be described with reference to Figs. 3 to 10 below.

[0045] As indicated above, the device of the present invention may be used also for cutting, rather than perforating a web material. Before describing in detail embodiments of the cutting or perforating device, with reference to Fig.2 the structure of the cutting device of an interfolding machine will be briefly described below.

[0046] With reference to Fig.2, the interfolding machine 200 comprises a first path for supplying a first continuous web material N1 of tissue paper and a second path for supplying a second continuous web material N2 of tissue paper. Along the first path there is arranged a first cutting unit or cutting device 201, which comprises a first blade-holder device supporting rotary cutting blades, hereinafter referred to as “rotary cutting roller” 203. The rotary roller 203 is provided with rotary cutting blades 203 A that are angularly spaced apart. The first rotary cutting roller 203 forms a blade holder of the cutting unit 201. The rotary cutting blades 203 A cooperate with a first stationary blade 204, hereinafter referred to as “anvil blade”, carried by a stationary, i.e., nonrotating, blade-holder device 204A. In the illustrated example, the stationary anvil blade 204 is helical-shaped, while the rotary cutting blades 203 A are straight-shaped, parallel to the rotation axis of the blade holder or rotary cutting roller 203. However,a reverse arrangement, with a straight stationary anvil blade and helical rotary cutting blades may not be ruled out.

[0047] Along the second path, a second cutting unit 202, substantially mirror-symmetrical to the first cutting unit 201, is arranged. The second cutting unit 202 comprises a blade-holder device supporting rotary blades, hereinafter referred to as “rotary cutting roller” 205, which is provided with blades 205A that are angularly spaced apart. The rotary cutting roller 205 forms a blade holder of the cutting unit 202. The blades 205A cooperate with a stationary, i.e., non-rotating, blade-holder device 206A of a second stationary blade, hereinafter referred to as “anvil blade” 206.

[0048] In a known manner, the first blade holder, or rotary cutting roller 203, and the second blade holder, or rotary cutting roller 205, are provided with suction openings or with other retention means, for retaining on the surface of the respective cutting rollers 203, 205 the sheets obtained by cutting the first and the second continuous web material Nl, N2, and to transfer said sheets from the cutting rollers 203, 205 to interfolding rollers 209, 211. Said interfolding rollers 209, 211 rotate around respective rotation axes parallel to each other and parallel to the rotation axes of the cutting rollers 203, 205. The two interfolding rollers 209, 211 form an interfolding nip 213. In a known manner, the interfolding rollers 209, 211 fold and interfold the sheets coming from the cutting devices 201, 202 to form a stack of sheets P.

[0049] Each continuous web material Nl, N2 is guided around the respective rotary cutting roller 203, 205 and is fed between the cutting roller or a rotary blade-holder 203, 205 and the stationary anvil blade 204, 206. The cooperation of the rotary cutting blades 203 A with the stationary anvil blade 204 cuts the continuous web material Nl into single sheets, which are then transferred from the first cutting roller or rotary blade-holder 203 to the first interfolding roller 209. Similarly, the continuous web material N2 is guided around the second cutting roller or rotary blade-holder 205 and cut into sheets through the cooperation of the rotary cutting blades 205 A with the stationary anvil blade 206. The individual sheets are then transferred from the second cutting roller or rotary blade-holder 205 to the second cutting roller 211.

[0050] The interfolding machine 200 described so far in summary is per se known. There are other types of interfolding machines which include r only one path for feeding only one web material, and which are always provided with at least one cuttingunit.

[0051] The brief above description of Figs. 1 and 2 has the purpose of showing by way of non-limiting example some types of machines in which a perforating or cutting device according to the present invention can be inserted. Further examples may be machines for packaging tissue paper tissue products, in which perforating and cutting units are usually present which are entirely similar to what has been described so far. Embodiments of such types of packaging machines are disclosed by way of example in EPl 899228, EP2766266, EP3625132.

[0052] Figs. 3 to 8 show an embodiment of one of the rotary or stationary blade holder devices for the rotary blades or for the stationary blades (or anvil blades) described with reference to Figs. 1 and 2. Those skilled in the art will understand that the structure described below and shown in Figs. 3 to 8 can be used to fit either a rotary blade or a stationary blade, or anvil blade. Furthermore, such structure may be used for fitting either a straight blade or a helical blade. By way of example Figs. 3 to 8 illustrate an application to a helical-shaped blade (either rotary or stationary).

[0053] Given that the blade-holder device of Figs. 3 to 8 can generally be used in any of the cutting or perforating devices described above, the components of the device of Figs. 3 to 8 are indicated with reference numerals different from those used in Figs. 1 and 2, even if such components are equal or equivalent to those already mentioned with reference to Figs. 1 and 2.

[0054] The blade-holder device of Figs. 3 to 8 is indicated with in its entirety with 100. The blade-holder device 100 comprises a support 103 which extends according to a longitudinal direction. In the case of a rotary blade-holder device 100, the longitudinal extension direction of the support 103 is parallel to the rotation axis. A seat in which a cutting or perforating blade, here labelled 107, is mounted, is indicated with 105. In some embodiments, the blade 107 may be a continuous blade. In other embodiments, the blade 107 may be formed by a plurality of blade segments aligned with each other in the seat 105.

[0055] As indicated above, both the seat and the blade may be straight or may extend helically around the longitudinal axis of the support 103.

[0056] The blade (or each blade segment) 107 is fixed in the seat 105 through one or more locking clamps 109. The position of the blade 107 is such that the cutting edge 107.1 thereof extends along the longitudinal extension of the seat 105 and of the support 103. If the blade 107 consists of multiple consecutive blade segments, a locking clamp 109 for each blade segment may be provided. However, this is not mandatory. For example, a number of locking clamps 109 greater than 1 for each blade segment may be provided. Or a locking clamp 109 may be used to lock multiple blade segments 107.

[0057] Each locking clamp 109 may be attached to the support 103 through one or more pins 111. In the illustrated embodiment, each pin 111 comprises a proximal end 111.1 and a distal end which forms a head 111.2. The proximal end may be threaded to engage a respective blind hole formed in the support 103.

[0058] Each pin 111 extends through a respective hole 113 made in the locking clamp 109. The holes 113 have an elongated shape, i.e., they are in the form of a slot, with a larger dimension parallel to the cutting edge 107.1 of the blade 107.

[0059] Each hole 113 is surrounded by an inclined surface 115 which forms the bottom of a seat 117, through which the respective pin 111 extends. A respective elastic member 119 associated with the corresponding pin 111 is housed in each seat 117. In the illustrated embodiment, each elastic member surrounds the respective pin 111.

[0060] Advantageously, in certain embodiments each elastic member 119 may comprise at least one Belleville washer 119.1. In the illustrated embodiment, each elastic member 119 comprises a plurality of Belleville washers 119.1. However, the use of different forms of springs, such as helical compression springs, or elastic members other than springs having an equivalent effect, is not excluded.

[0061] Each elastic member 119 is retained between the head 111.2 of the respective pin 111 and a washer consisting of a wedge-shaped element 121. The wedge-shaped element is an element which has a variable thickness in the elongation direction of the slot forming the hole 113. Therefore, in the illustrated example, the wedge-shaped element 121 has a variable thickness in the direction parallel to the cutting edge 107.1 of the blade 107. Each wedge-shaped element 121 has a central hole, through which the respective pin 111 extends.

[0062] As shown in Figs. 5 and 7, the wedge-shaped element has a lower surface 121.1, facing towards the proximal end 111.1 of the pin 111, and a upper surface 121.2 facing towards the head 111.2 of the pin 111.

[0063] The lower surface 121.1 is in contact with the inclined surface 115 and has an inclination equal to the inclination of the inclined surface 115. In this manner, a mutual movement between each pin 111 and the locking clamp 109 in the longitudinal direction 103 of the support (indicated by the double arrow F in Figs. 5 and 7) causes a sliding of the inclined surface 115 along the lower surface 121.1 of the wedge-shaped element 121. The wedge-shaped element 121 may preferably be made of a material different from that of the locking clamp 109. For example, it may be made of bronze or other material that facilitates the sliding of the inclined surface 105 along the lower surface 121.1.

[0064] Due to the inclination of the inclined surface 115 and the change in thickness of the wedge-shaped element 121 (and therefore the inclination of the lower surface 121.1 thereof), the mutual movement between the locking clamp 109 and the pins 111 causes compression or loosening of the elastic member 119, depending on the direction in which the movement occurs, and which serves alternately to tighten, i.e., to lock the blade 107 in the seat 105 and to release it, to allow the adjustment of the position or the replacement thereof, for example

[0065] This effect is particularly shown in Figs. 5, 6 and 7.8. In Figs.5 and 6, the mutual position between the wedge-shaped elements 121 and the locking clamp 109 is such to bring the elastic member 119 to the position of maximum compression, due to the sliding of each wedge-shaped element 121 towards the head 111.2 of the pin 111, caused by the thrust generated on the wedge-shaped element 121 by the inclined surface 115. In this position, the elastic members 119 generate a thrust of the locking clamp 109 against the blade 107 positioned in the seat 105. Therefore, in the position of Figs. 5 and 6, the blade 107 is clamped in the seat 105 by the clamp 109.

[0066] When the clamp 109 is displaced from the position of Fig. 5 to the position of Fig.7, i.e., from left to right in the drawing, each elastic member 119 can expand, due to the movement of the respective wedge-shaped element 121 toward the distal end 111.1 of the pin 111. As a result, the pressure exerted by the elastic members 119is reduced or completely eliminated. In the illustrated embodiment, the displacement according to arrow F and the inclination of surface 115 and of the wedge-shaped element 121 are such to bring to zero the force exerted by each elastic member 119 on the locking clamp 109, and therefore on the blade 108, and such to generate between a lower surface (that is facing towards the proximal end 111.1 of the pin 111) of the locking clamp 109 and the support 103, a space greater than the thickness of the blade 107.

[0067] In this manner, in the position of Figs.7 and 8, the blade 107 may be removed from its seat 105 and / or a different blade may be inserted into the seat. Upon correctly positioning the blade 107 into the seat 105, each clamp 109 may be displaced from the position of Figs. 7 and 8 to the position of Figs. 5 and 6, once again locking the blade on the support.

[0068] In order to control the movement according to the double arrow F of each locking clamp 109, in some embodiments, the locking clamp 109 may be provided with a shape that allows the engagement thereof with a special operating tool. The tool is shown in Figs. 4 and 9, and is indicated in its entirety with 131. In this example, the operating tool 131 comprises a handle 131.1, a wheel 131.2 rotatable around an axis X, and a cylindrical pin 131.3 with an axis Y parallel to the axis X. The axes X and Y are spaced apart from each other, i.e., the wheel 131.2 is eccentric with respect to the pin 131.3.

[0069] Each clamp has a seat 133 for the operating tool 131. The seat 133 may be arranged at the centre of the longitudinal extension of the locking clamp 109. In some embodiments, the seat 133 has two flat surfaces parallel to each other and at a distance equal to the diameter of the wheel 131.2. The two surfaces may be formed by respective dowels 135 fixed to the locking clamp 109 by means of screws 137. In other embodiments, the dowels may be omitted and the flat surfaces may be directly formed by the material which forms the locking clamp 109.

[0070] At the two flat surfaces, the locking clamp 109 has a through opening 139 aligned with a bushing 141 fixed to the support 103 and oriented with an axis thereof orthogonal to the longitudinal extension of the locking clamp 109. The bushing 141 has an inner diameter approximately equal to the outer diameter of the pin 131.3 of theoperating tool 131.

[0071] In order to move the locking clamp 109 in the direction F and therefore cause the tightening and loosening thereof, the operating tool 131 is engaged to the support 103 by inserting the pin 131.3 into the bushing 141 and the wheel 131.2 in the seat 133 between the two flat surfaces formed by the dowels 135. Due to the eccentricity between the axes X and Y, the rotation of tool 131 around the axis Y, obtained by rotating the pin 131.3 in the bushing 141, generates a thrust of the eccentric wheel 131.2 against one or the other of the two flat surfaces formed by the dowels 135. Due to the eccentricity between the wheel 131.2 and the pin 131.3 which forms the rotation axis of the operating tool 131, a translation movement of the locking clamp 109 along the direction F is obtained.

[0072] In the illustrated embodiment, the movement of the locking clamp 109 is guided in a sliding seat 145 formed in the support 103. The sliding seat 145 is arranged side by side and adjacent to the seat 105 for the blade 107. The locking clamp 109 may comprise a protrusion 109.1 housed in the sliding seat 145 and a side relief 109.2 forming a pressure surface adapted to press against the blade 107 housed in the seat 105 of the blade.

[0073] In some embodiments, above and below the blade 107 elastic elements 147 and 149 are arranged (see Fig.9), to dampen the vibrations of the blade 107. In particular, the elastic element 147 is positioned between the blade 107 and the seat 105 and the elastic element 149 is arranged between the blade 107 and the locking clamp 109.

Claims

CLAIMS1. A blade-holder device for a blade for cutting or perforating a web material, wherein the blade-holder device comprises:a support extending according to a longitudinal direction;at least one seat for a blade, formed in the support and extending in the longitudinal direction of the support; wherein the seat is configured to receive and retain a blade directed with a cutting edge extending in the longitudinal direction of the support;at least one locking clamp constrained to the support;an elastic member constrained to the support and configured to push the locking clamp towards the seat for the blade and generate a clamping force on the blade positioned in the seat for the blade;a wedge-shaped element arranged between the elastic member and an inclined surface of the locking clamp; wherein the wedge-shaped element has a variable thickness along a sliding direction, the locking clamp being movable along the sliding direction with respect to the support; wherein the elastic member is arranged to press the wedge-shaped element against the inclined surface of the locking clamp, the movement of the locking clamp in the sliding direction causing a sliding of the inclined surface of the locking clamp along the wedge-shaped element and a resulting clamping and release of the locking clamp with respect to the seat for the blade.

2. The blade-holder device of claim 1, wherein the sliding direction is directed according to the longitudinal support direction.

3. The blade-holder device of claim 1 or 2, wherein the elastic member is constrained to the support through a pin which traverses the locking clamp and the wedge-shaped element and it is fixed to the support.

4. The blade-holder device of claim 3, wherein the elastic member surrounds the pin.

5. The blade-holder device of claim 4, wherein the elastic member comprises one or more Belleville washers concentric to the pin.

6. The device of any one of claims 3 to 5, wherein the pin has a first end constrained to the support and a second end forming a head which retains the elastic member and the wedge-shaped element, the elastic member being arranged between the head of the pin and the wedge-shaped element.

7. The blade-holder device of one or more of the preceding claims, wherein the wedge-shaped element is housed in a seat formed in the locking clamp and having a bottom forming an inclined surface of the locking clamp.

8. The blade-holder device of claim 7, wherein the seat is slot-shaped with an extension in the sliding direction.

9. The blade-holder device of claim 7 or 8, when appended to at least one of claims 3 to 6, wherein the pin passes through the bottom of the seat.

10. The blade-holder device of one or more of the preceding claims, wherein the locking clamp comprises a seat for an operating tool whose seat is superimposed to a through hole in the locking clamp for introducing a stem of the operating tool.

11. The blade-holder device of claim 10, wherein the seat for the operating tool comprises two substantially flat surfaces which are parallel and opposite to each other and extend transversely to the sliding direction.

12. The blade-holder device of one or more of the preceding claims, wherein the support comprises a sliding seat in which the locking clamp is slidably guided.

13. The device of claim 12, wherein the sliding seat is arranged side by side and adjacent to the seat for the blade, and wherein the locking clamp comprises a protrusion housed in the sliding seat and a lateral projection forming a pressure surface adapted to press on the blade housed in the seat for the blade.

14. The device of claim 11 or 12, when dependent on at least one of claims 3, 4, 5, 6 and 9, wherein the pin is fixed in the sliding seat.

15. A blade-holder device for a blade for cutting or perforating a webmaterial, wherein support comprises:a support extending according to a longitudinal direction;at least one seat for a blade, formed in the support and extending in the longitudinal direction of the support; wherein the seat is configured to receive and retain a blade directed with a cutting edge extending in the longitudinal support direction;at least one locking clamp constrained to the support;a plurality of pins which pass through the locking clamp which have a proximal end constrained to the support and a distal end forming a head;for each pin, an elastic member and a wedge-shaped element, constrained to the pin and arranged between the head of the pin and the locking clamp, the elastic member pushing the wedge-shaped element towards the locking clamp;wherein the wedge-shaped element has a variable thickness along a sliding direction in which the clamp may slide with respect to the support; wherein each elastic member is arranged to press the wedge-shaped element against a respective inclined surface of the locking clamp; wherein the movement of the locking clamp in the sliding direction causes a sliding of the inclined surface of the locking clamp along the wedge-shaped element and a resulting clamping and release of the locking clamp with respect to the seat for the blade.

16. A cutting or perforating device, comprising a rotary blade-holder device for at least one rotary blade and a stationary blade-holder device for a stationary blade cooperating with a rotary blade, wherein at least one of said rotary blade-holder and said stationary blade-holder device is a blade-holder device according to one or more of the preceding claims.

17. The cutting or perforating device of claim 16, wherein the stationary blade and the rotary blade are arranged to carry out a scissor cutting, one of said stationary blade and said rotary blade having a helical shape and the other preferably having a straight shape.

18. A machine for transforming a continuous web material, comprising a supply path for the web material and a cutting or perforating device according to claim 16 or 17.

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