DEVICE FOR DISPENSING PAPER SECTIONS OF PREDETERMINED LENGTH

This application claims priority to German patent application number 10 2017 110 518.2, filed May 15, 2017, the contents of which are incorporated herein by reference.

The invention relates to a device for dispensing paper sections of predetermined length in accordance with the pre-characterizing clause of claim 1.

A device for dispensing paper sections as well as a knife for a device of this type are known from DE 20 03 354 A. This prior art device comprises a perforating device, which divides the paper web into individual sheets and comprises a rotatably supported knife with a perforating cutting edge, as well as a slotted roller that rotates synchronously with the knife and has a slit to accept the knife. The cutting edge of the knife is embodied with a sawtooth shape. Additionally, the knife comprises a plurality of grooves, into which engage the ridges of a counterpart when the knife is moving into the immediate vicinity of the slotted roller and is moving past it in a rotating manner. The knife passes the slotted roller in a rotating manner, so that the radially outer part of the knife engages into the slit and the knife's cutting edge perforates the entire width of the paper web, with the exception of those parts of the paper web that are situated opposite the grooves. The unperforated portions of the paper web possess sufficient tensile force to allow the user to pull the paper web from the dispenser using a gentle steady pulling force.

DE 28 14 792 A1 relates to a device for issuing paper sections of a predetermined length and comprises a device for separating the paper section from the paper web wound onto a paper roll and for allowing easy access to the paper web following the dispensing of the separated paper section, whereby the device is operated by pulling on a paper end. The device consists of at least one cutting roller, which has a width that corresponds to at least the width of the paper web, and which features a cutting line that at least partially encloses an angle α—different from zero—with the generatrix of the cutting roller. The cutting roller comprises a fixed knife, which substantially extends over the entire width of the roller and protrudes from the roller shell. Associated with the cutting roller is a pressure roller, which has a slit-shaped opening that matches the knife arrangement. The two rollers are coupled to each other by means of geared wheels, which possess a partial circle diameter that corresponds to the roller diameters, and which effect a synchronous movement of the roller in such a way that the paper web—stretched tightly across the slit-shaped opening—is perforated by a knife, whereby during the course of this cutting process the knife penetrates into the slit-shaped opening.

The knife comprises a cutting edge that is embodied sawblade-like. According to this prior art, a cutting line of the knife forms an angle α with the generatrix of the cutting roller, whereby the angle corresponds to the constant angle of inclination of the helical line. Pulling the end of the paper web results in a rotation of the cutting roller by way of frictional contact. The knife engaging the paper web, which has been stretched tight with the help of the deflection roll, marks the start of the separation process of the paper section from the subsequent paper web. This separating process is not completed before the end of the knife engages with the paper web and a sufficiently large piece of the following paper web protrudes from the dispenser and is easily accessible by hand for the subsequent paper dispensing process.

EP 1 153 565 A1 relates to a mechanism for cutting and providing sections of a tape material, in particular paper towels, comprising at least one cylinder, which in a support structure is free to rotate about one axis and drags along an end section of at least one web, whereby arranged in the cylinder is/are one or several movable knife/s, which may protrude from the cylinder for cutting the end section of the paper web, whereby the knifes are connected to a shaft that is free to rotate about one axis, e.g. oriented parallel to the longitudinal axis of the cylinder. The shaft comprises at least one first means, which protrudes from one side of the cylinder and is free to rotate about an angular portion of a circumference. The rotational movement is effected by at least one second means, which shifts along a direction parallel to the longitudinal axis of the movable knife and rotates about the axis, whereby the rotation-translation movement of this second means is synchronized to the rotational movement of the cylinder. The rotational movement of the cylinder is initially started by pulling on the paper web for a distance equivalent to half a rotation, whereby subsequently the second half rotation is caused by a tension spring, which is connected between a side wall and a geared wheel that is connected to the axle of the cylinder. A knife with a sawtooth geometry is used for cutting the paper.

DE 36 90 545 T1 relates to a dispenser for rolls of flexible tape material, comprising a feed roll and a cutter blade. The cutter blade consists of a series of teeth, which are arranged some distance from each other along the length of the blade. In this prior art, four pairs of teeth are present along the length of the blade, whereby these pairs of teeth are separated by cut-outs. Employing this shape of cutting edge allows the cutting action that is performed on the web of the flexible band material when it is supplied via the feed roll to result in a straight cut that extends in parallel to the axis of the feed roll, but this leaves three small sections of the web uncut, which correspond to the width of the sections and to the length of the sections still on the circumferential surface of the feeder roll.

By leaving these small uncut sections of the web, which across the width of the web contain a section between each other, serves to maintain the continuity of the web, when the web has essentially already been cut but still remains within the confines of the dispenser chassis before reaching the dispensing outlet. When the web is pulled further out of the dispenser housing by the future user of the now determined sheet length, the future user applies a low level of pulling force, which very easily separates the spaced-apart uncut sections, which are formed by the configuration of the cutting blade and the spacing between the slits arranged in the circumferential surface of the feed roll.

U.S. Pat. No. 2,601,956 A relates to a device for dispensing paper sections of a predetermined length that comprises a device that is actuated by pulling the end of the paper web. The device comprises a pressing element that bears upon a circumferential surface of the paper roll and is in spring-loaded contact with the circumferential surface. A free end of the pressing element is oriented in the direction of movement of the paper roll.

DE 40 04 124 A1 relates to a device for dispensing web sections from a delivery roll. The device comprises a spring-loaded pressing element that bears upon a circumferential surface of the paper roll. A free end of the pressure element is oriented in a direction opposite to the direction of movement of the paper roll.

Due to the paper roll's moment of inertia, prior art devices without a pressure spring are susceptible to the problem that the paper roll continues to turn because of its inertia after the paper section withdrawal has ended, so that a jam of the paper web before entering the device for separating the paper web sections can not be ruled out.

Prior-art embodiments with spring-loaded pressing elements face the problem that when exchanging the paper roll, the spring-loaded pressing element must be actuated by service personnel in order to remove a spent paper roll and to insert a new paper roll. This entails the risk that the pressing element is not returned to its original position

Starting from this basis, the objective of the present invention is to further develop a device of the type mentioned above in a way so that paper webs of high strength and elasticity can be cut and dispensed in a reliable and trouble-free manner.

In particular, paper jams in the device are to be prevented by simple means and the exchange of paper rolls is to be simplified.

This objective is met by the invention for example with the features of claim 1.

The device comprises a pressure spring that bears upon the circumferential surface of the paper roll, whereby a free end of the pressure spring is oriented in a direction opposite to the direction of movement of the paper roll.

In comparison to the prior art, the use of a pressure spring realizes the advantage that a jam of the paper web prior to its entry into the device for separating the paper sections can be avoided, since the paper web issuing from the paper roll is kept under tension by the pressure spring.

The pressure spring is embodied rod-shaped and is connected pivotally with a part of the housing of the device. This allows the pressure spring to be pivoted from a vertical operating position into a horizontal service position to release the paper roll.

It is further intended that the length of the pressure spring is such that in its pivoted position, the end of the pressure spring projects beyond the edge of the housing of the device, which prevents the cover of the housing from closing. This means that the housing can only be closed if the pressure spring is in its operating position.

Especially preferred is an embodiment in which the end of the pressure spring is in contact with the circumferential surface of the paper roll approximately tangentially. On the one hand this realizes an effective stop of the paper roll after the withdrawing process and on the other hand the forces acting upon the paper roll are low enough to not negatively affect the withdrawal of a paper section from the device.

In order to allow a frictionless relative movement between the surface of the paper roll and the end of the pressure spring, it is intended that the end of the pressure spring is rounded. In the horizontally pivoted state, the rounded end prevents the housing cover from closing, since part of the edge of the side wall of the cover extends along the pressure spring and is blocked by the rounded end.

The pressure spring preferably consists of flat spring steel.

Further details, advantages, and features of the invention are not only found in the claims, the characteristic features listed therein—individually and/or in combination—but also in the following description of the figures.

The figures show:

FIG. 1 shows a front view of a device for dispensing paper sections of a predetermined length without the covering hood,

FIG. 2 shows in a sectional view the device of FIG. 1 along a section line A-A, with paper roller, cutting roller, and pressure roller,

FIG. 3 shows a lateral view of the device of FIG. 1, from the left, with gearwheel transmission and return spring,

FIG. 4a) shows a lateral view of the gearwheel transmission with return spring of FIG. 3 in its neutral position,

FIG. 4b) shows in a sectional view the roller arrangement in its neutral position,

FIG. 5a) shows a lateral view of the gearwheel transmission in the knife-entry position,

FIG. 5b) shows in a sectional view the roller arrangement in the knife-entry position,

FIG. 6a) shows a lateral view of the gearwheel transmission in the engaged-knife position,

FIG. 6b) shows in a sectional view the roller arrangement in the engaged-knife position,

FIG. 7a) shows a lateral view of the gearwheel transmission in the knife-withdrawal position,

FIG. 7b) shows in a sectional view the roller arrangement in the knife-withdrawal position,

FIG. 8 shows a lateral view of the device of FIG. 1; seen from the right, with hand wheel,

FIG. 9 shows a perspective representation of a pressure roller,

FIG. 10 show a perspective representation of the cutting roller with knife,

FIG. 11a) shows a top view onto the knife, and

FIG. 11b) shows a lateral view of the knife.

FIG. 1 shows a front view of a device 10, referred to as a paper dispenser hereinafter, for dispensing paper sections of a predetermined length. The device comprises a housing 12 with a rear wall 14 to be mounted to a wall (not illustrated), as well as a covering hood 16. From the rear wall 14 extend holding elements 18, 20 for accommodating a paper roll 22. From the paper roll 22 issues a paper web 24, which is accommodated in a device 26 for separating and dispensing paper sections. The device 26 comprises a right-side wall 28 as well as a left-side wall 30, which are connected to the rear wall 14. The side walls 28, 30 are connected on the front side via a brace 32. From the brace 32 extends along the vertical direction a pressure spring 34, which is in contact with a surface 36 of the paper web 24 or the paper roll 22 and prevents creasing of the paper web 24. The pressure spring is pivotably mounted around a hinge 38 and can be pivoted laterally to the right or the left to facilitate exchanging the paper roll 22. The length of the pressure spring is such, that the pressure spring 34 in its laterally pivoted position prevents the covering hood 16 from closing.

FIG. 2 shows a sectional view of the paper dispenser 10 along the section line A-A. The device 26 comprises a cutting roller 40 with a fixed knife 42 that extends along the longitudinal axis of the cutting roller as well a pressure roller 44 with a slit-shaped opening 46, which extends along the longitudinal direction of the pressure roller 44, and into which the knife 42 can engage during a synchronous movement of the rollers 40, 44. Each of the rollers 40, 44 is supported in the side walls 28, 30 by shaft journals 48, 50. At their ends, each of the shaft journals 48, 50 features geared wheels 52, 54 or 56, 58, which serve to couple the rollers 40, 44.

Deflecting rollers 60, 62 are provided for guiding the paper web, each of which is supported on an axle 64, 66, which extend between the side walls 28, 30.

The paper web 24 is deflected by the deflecting rolls 60, 62 and is guided along a circumferential section 72 around the pressure roller 44 by circumferential guide elements 68, 70. One end 74 of the paper web 24 is guided through a withdrawal opening 76 in the covering hood 16 and may be grasped by a user. To ensure that the end of the paper web 74 is guided into the withdrawal opening 76, a guide element is provided in the area of the withdrawal opening 76 and extends along the pressure roller 44 between the side walls 28, 30.

The guide elements 68, 70 are connected in the area of the cutting roller 40 by guide lands 71 that extend in the circumferential direction and are arranged spaced apart. The guide lands 71 serve to guide the paper web 30 in the region of the guide elements 68, 70, where the knife 42 engages into the opening 46 of the pressure roller 44.

FIG. 3 shows a lateral view of the paper dispenser 10 and illustrates the geared wheel 52 of the cutting roller that is connected to the shaft journal 48, as well as the geared wheel 56 of the pressure roller 44 that is connected to the shaft journal 50. The geared wheels 52, 56 form a gear unit with a 1:1 transmission ratio and effect a synchronous motion of the rollers in such a way that the paper web 24, which has been stretched tightly along the circumferential surface 72 of the pressure roller 44, is cut or pierced by the knife 42 when the paper end 74 is being pulled, whereby during this cutting operation the knife 42 penetrates into the slit-like opening 46.

The geared wheel 52 is coupled to the lateral wall 30 via a tension spring 80 in a way so that a pulling movement acting on the paper end 74 in the direction of the arrow 82 in accordance with FIG. 2, effects a rotation of the pressure roller 44 in the direction of the arrow 84, on account of a frictional engagement between the paper web 24 and the circumferential surface of the pressure roller. Due to the coupling of the geared wheels, the geared wheel 48 is moved in the direction of the arrow 86, which results in a tensioning of the tension spring 80. After half a rotation of the pressure roller 44, the tension spring has reached its maximum tension, so that during continued pulling of the paper end 74 the tension spring 80 contracts, which effects an automatic further conveyance, which in turn guides a new paper end from the opening 76.

FIGS. 4 to 7 show individual positions of the cutting roller 40 relative to the pressure roller 44 when a pulling motion acts on the paper end 74.

FIGS. 4a) and 4b) show the geared wheels 48, 50 and the rollers 40, 44 in a neutral position, in which the tension spring 80 is relaxed. In this, an effective line 88 of the tension spring 80 extends substantially perpendicular to a line 90 that connects the shaft ends 48, 50. The paper web 24 is in contact with the pressure roller 44 along its circumferential surface and is pulled tight in the area of the slit-shaped opening 46.

FIGS. 5a) and 5b) show the geared wheels 48, 50 as well as the rollers 40, 44 in a knife-engaging position, e.g. after a rotation of approximately 25°, whereby the knife 42 penetrates the paper web and enters into the slit-shaped opening 46, which starts the separation process. In this position, the knife 42 comes into contact with the paper web. Pulling the paper end 74 even further results in an at last sectional separation (perforation) of the paper section by the penetration of the knife 42 into the slit-like opening 46.

FIGS. 6a) and 6b) show the geared wheels 46, 50 and the rollers 40, 44 in the engaged-knife position, in which the knife 42 is completely accommodated in the slit-like opening 46.

Pulling the paper end 74 results in the tension spring 80 being further tensioned, whereby pursuant to FIG. 7a) and FIG. 7b) the knife 42—after a rotation of approximately 120°—is no longer engaged in the slit-like opening 46 (knife withdrawal position).

Pulling the paper end 74 serves to further tension the tension spring 80, until the rollers 40, 44 have completed half a rotation. After the effective line 88 of the tension spring 80 has crossed the centre of the geared wheel, the contraction of the tension spring 80 results in an automatic further conveyance of the paper web 24, together with the separated paper section. Subsequently, the paper section 74 can be separated from the paper web 24 along the perforated cutting line.

FIG. 8 shows a lateral view of the paper dispenser 10 from the right side and shows the geared wheels 54 and 58, which are in an engaged position. A hand wheel 92 is coupled to the geared wheel 58 for the pressure roller 44. The hand wheel 92 facilitates a manual operation of the pressure roller 44 for threading the paper web 24, e.g. after the paper roll 22 has been exchanged.

The geared wheel 58 of the pressure roller 44 interacts with a locking lever 94, which is pivotably mounted on a rod 96. The locking lever locks the geared wheel 58 along the direction of the arrow 94.

FIG. 9 shows a perspective representation of the pressure roller 44 with the shaft 50 and the slit-shaped opening 46. The slit-shaped opening 46 extends along the longitudinal direction of the pressure roller 44 all along the latter's longitudinal extent. The slit-shaped opening 46 comprises four sections 98, 100, 102, 104, which are separated by bridges 106, 108, 110 extending in the radial and the circumferential direction.

FIG. 10 shows a perspective representation of the cutting roller 40 with the fixed knife 42. The knife 42 comprises a knife edge 112 as well as a knife blade 114, which is accommodated in the cutting roller 40. In the illustrated embodiment example, the cutting roller 40 comprises two elements 116, 118, which possess a semi-circular cross-section, and in between which the knife blade 114 is clamped.

The knife edge 112 comprises four sections 120, 122, 124, 126, which are separated from each other by cut-outs 128, 130, 132. The individual sections 120, 122, 124, 126 of the knife edge 112 engage into the sections 98, 100, 102, 104 of the slit-shaped opening 46, whereby the bridges 106, 108, 110 engage into the cut-outs 128, 130, 132. The outer surface 134 of the cutting roller 40 is provided with circumferential grooves 136, 138, 140, which corresponding to the cut-outs 128, 130, 134. The circumferential grooves 136, 138, 140 engage into the guide lands 71 of the circumferential guide elements 68, 70, whereby the guide lands extend circumferentially and transversely to the longitudinal axis of the cutting roller 42, so that a section of the circumferential surface 134 of the cutting roller 42 together with the inner surface of the guide lands 71 forms a guide surface, which simplifies the guiding of the paper web, in particular during the threading process.

FIG. 11a) shows a top view onto the knife 42, comprising the knife edge 112 as well as the knife blade 114. The knife 42 is embodied as a stamped part.

FIG. 11b) shows a lateral view of the knife 42. The knife edge 112 is bent relative to the knife blade 114 by an angle α, with α in the range of 20°≤α≤60°, preferably α=30°. This ensures that the knife edge 112 enters the slit-shaped opening 46 at an optimum angle for cutting the paper web 24.

In accordance with an aspect of the invention with independent inventive merit, the outer sections 120, 126 possess a triangular cutting edge, whereby sections 142, 144 or 146, 148 of the cutting edge are embodied with an obliquely downward shape in the direction towards the lateral edges 150, 152 or the cut-outs 128, 132.

The invention's embodiment is characterized in that the cutting edges of the central sections 122, 124 have flanks 154, 156; 158, 160 that rise in the direction of the cut-outs 128, 130, 132, which serves to ensure that cutting edge sections 162, 164, 166, 168 of the longest possible length are formed adjacent to the cut-outs 128, 130, 132, whereby the cutting edge sections interact with the bridges 106, 108, 110 of the pressure roller to cut the paper web in a precise manner, which in turn facilitates a simple tear-off action.

With respect to the invention's embodiment of the knife edge 112, it should also be noted that because of the cut-outs 128, 130, 132 the paper web 24 is only subjected to a type of perforation, instead of being subjected to a complete continuous cut, so that even after the cutting process, the automatic advance due to the tension spring 80 is sufficient to transport the paper section 74 to be torn off out of the paper dispenser, without any risk of a paper jam. After the perforated paper section 74 has been dispensed through the opening 76, it may simply be torn off by a user, which separates the remaining strands in the paper web 24.

This requires only minimal pulling forces, whereby a further conveyance of the paper web 24 is prevented by the restoring force of the tension spring 80.

As a result of the invention's embodiment of firstly the knife edge 112 in interaction with the slit-shaped opening 46 with the sections 98, 100, 102, 104 as well as the bridges 106, 108, 110, and secondly by fine-tuning the spring tension of the tension spring 80, the invention's embodiment allows the cutting or rather perforating of paper webs of different density and strength. In particular, the invention's paper dispenser 10 is to convey paper webs with a density of 2×25 g per mm², i.e. paper webs that usually can only be used in electrically operated paper dispensers. In the prior art, mechanically operated paper dispensers are usually operated using thin paper webs with a density of 2×17 g per mm², i.e. single-layer paper.

DEVICE FOR DISPENSING PAPER SECTIONS OF PREDETERMINED LENGTH

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