EP0061773B1 - Severing device for typewriting and printing apparatus - Google Patents

Description

The invention relates to a separating device for writing and printing units for separating sections of web-shaped recording media, comprising a stationary knife extending transversely across the web width of the recording media and a cooperating with it, which can be rotated back and forth by a drive device about a knife axis parallel to the stationary knife Rotary knife, which has a cutting edge running at an angle to the knife axis, wherein in the direction of advance behind the rotary knife and parallel to it, a take-off roller is rotatably mounted, which intermittently acts on the recording medium in such a way that it stands still during the cutting movement of the rotary knife and during the reverse rotation of the Rotary knife removed the separated web section (DE-A-2 336 028).

A separating device is known from German utility model 7 408 722, which is used for separating documents in a cash register. In this separating device, the rotary knife is made from a round rod which has a flat surface which extends at least approximately through the rod axis, so that the rotary knife has the shape of a semi-cylindrical rod. The cutting line forms the cutting line between the flat surface and the outer surface of the round rod.

Such a rotary knife may be suitable for cutting through relatively narrow strips of paper, such as are used in cash registers. In contrast, such a rotary knife would not be suitable for severing wide paper webs and in particular of continuous form sets, such as those used in writing and printing units. In order to achieve a shear effect between the cutting edge of the rotary knife and the cutting edge of the stationary knife, the cutting edge of the rotary knife must run at a certain angle to the knife axis. This angle must be steeper, the stronger the paper web that is to be severed in order to keep the force required for severing or the torque to be transferred to the diameter relatively small. In order to allow such a course of the cutting edge on a rotary knife of the known type suitable for cutting wide paper webs, the rotary knife would have to have a considerable diameter. This in turn increases the mass of the rotary knife considerably, so that large torques must be applied in order to rotate the rotary knife quickly back and forth. It should be borne in mind that the cutting process must also take place very quickly in accordance with the high writing speed of the writing and printing units.

German utility model 7 408 722 says nothing about how the cut documents are removed from the separation point. In the case of fast-working writing and printing units, however, it is necessary to remove the separated sections immediately from the separation point and, if necessary, to stack them automatically. As a rule, this requires means for holding the sections to be separated off during the separation process and a conveying device for removing the separated section.

From DE-A-2 336 028 a separating device of the type mentioned at the outset is already known, which is used for cutting individual sheets of paper from a fed paper web of a copy paper roll in a copying machine. In this separating apparatus, the rotary knife of two discs, three strip-shaped blade between which are arranged at equal angular distances, each consisting of two at an obtuse _'angle mutually inclined sections with rectilinear cutting edges consists. The paper web to be cut is passed between the knives of the rotary knife. During the cutting process, the paper web is clamped between two stationary knives so that it cannot slip. The cut paper sheet is removed from a take-off device, which comprises a permanently driven take-off roller and a pressure roller that can be pressed against it. During the cutting process, the pressure roller is lifted off the take-off roller, so that the section to be separated remains at rest during the cutting process. The rotary knife is moved back and forth for the cutting process. This movement is done with the help of two magnets and one. the lever engaging the knife. In this separating device, too, the rotary knife is relatively heavy due to its construction, so that a relatively large amount of force is required to operate it. In addition, the separating device known from DE-A-2 336 028 appears unsuitable for being combined, for example, with a conventional typewriter or a conventional printer.

From FR-A-401 623 a separating device is also known which comprises two coaxially inserted hollow cylinders, each having diametrically opposite openings and one of which forms the stationary knife with one edge of its openings, while the other, opposite the first Cylinder rotatable cylinder that forms a rotary knife with a spiral cutting edge. Because of its construction, this solution also seems unsuitable for being combined with a conventional writing or printing device.

The invention is based on the object of specifying a separating device of the type mentioned at the outset which also enables the cutting through of broad web-shaped recording media, in particular multilayer continuous form sets with a relatively low expenditure of force, for safe removal of the separated ones Sections guaranteed and, if necessary, can also be subsequently combined with conventional writing and printing units.

This object is achieved in that the - viewed in the feed direction of the recording medium - arranged behind the recording point rotary knife is formed by a hollow cylinder, the jacket of which has diametrically opposite openings which form a passage for the recording medium over a length corresponding to the web width extend of the hollow cylinder and one of which is delimited on one longitudinal side by a spiral cutting edge, and in that the stationary knife, the rotary knife and the take-off roller are arranged in a frame which is detachably connectable to the writing mechanism and which drives a drive motor which drives the rotary knife and the take-off roller via a gear wearing.

Due to the known design of the rotary knife as a hollow cylinder, the rotary knife can have a relatively large diameter with low mass, so that the cutting edge forms a sufficiently large angle with the knife axis even with a relatively large axial length of the knife axis in order to have a good shear effect together with to ensure the stationary knife. Despite the large diameter of the rotary knife, there are no difficulties in guiding the record carrier since it passes through the rotary knife. The rotary knife serves at the same time to catch the separated section, so that it remains on the take-off roller until it is removed from the take-off roller after the separation process has ended. This eliminates the need for support elements or counter-pressure rollers, which would otherwise be required to hold the separated section. Due to the arrangement of the stationary knife, the rotary knife and the take-off roller in a frame which can be detachably connected to the writing mechanism and which carries a drive motor which drives the rotary knife and the removal roller via a gear, the separating device forms a closed unit which is designed to save space and optionally with the writing mechanism is connectable. Because of the design according to the invention, the separating device can be placed on conventional writing mechanisms without the writing mechanism itself having to be changed.

According to a preferred embodiment, the frame comprises two end shields in which the rotary knife and the take-off roller are rotatably mounted and which are connected to one another by a beam carrying the stationary knife. The connection between the separating device and the writing mechanism is facilitated, for example, by the fact that grippers, which are pretensioned in their closed position, are formed on each bearing plate, with which the separating device can be releasably fixed to the shaft of the platen roller of the writing and printing unit. These grippers thus form a snap or snap connection, with which the separating device can be easily attached to the writing device and can be removed again from it.

The drive motor is preferably fastened to one of the end shields and drives a shaft, which is mounted in both end shields and is directed parallel to the rotary knife, which in turn is in drive connection with the rotary knife via a gear mechanism arranged on the longitudinal ends of the rotary knife. As a result, the rotary knife is driven from both ends, so that twisting of the rotary knife is avoided during the cutting process.

In order to switch the direction of rotation of the drive motor after the cutting process and to stop the motor after the rotation of the rotary knife has ended, control surfaces can be provided on the shaft of the rotary knife, which interact with microswitches assigned to the shaft for controlling the drive motor.

Preferably, a freewheel is arranged in the gear connection between the drive motor and the take-off roller in such a way that it prevents torque transmission from the drive motor to the take-off roller during the cutting process. This gives the possibility in a simple manner to drive the take-off roller and rotary knife with the same drive motor and still achieve the desired intermittent drive of the take-off roller.

According to a preferred embodiment it is provided that a pulley is arranged on the shaft of the drive motor and the take-off roller, over which a crossed belt is guided, and that the freewheel is arranged in one of the pulleys.

In order to facilitate automatic threading of the leading edge of the record carrier coming from the writing point through the rotary knife, a guide surface which extends over the length of the openings and leads to the outlet end of the passage channel is preferably arranged in the hollow cylinder. The guide surface can be assigned a guide element which can be pivoted between the end shields about an axis parallel to the knife axis and which projects with its one longitudinal edge into the rotary knife and extends to a point above the take-off roller.

Since the take-off roller works without a counter-pressure roller and is intended to hurl the loose section lying loosely on it, it is expedient if the take-off roller is provided with a coating having a high coefficient of friction on at least part of its circumferential surface. This covering can be formed, for example, by some rubber rings, which are distributed at axial intervals over the length of the take-off roller.

• Fig. 1 eine teilweise schematische perspektivische Darstellung eines Schreibwerkes mit integriertem Schubtransport für einen Formularsatz sowie einer dem Schreibwerk zugeordneten Trennvorrichtung,
• Fig. 2 eine schematische Darstellung des Übersetzungsgetriebes für den Antrieb der Schreibwalze des Schreibwerkes und des Schubtransportes,
• Fig. 3 einen schematischen Teilschnitt durch das Schreibwerk mit aufgesetzter Trennvorrichtung senkrecht zur Achse der Schreibwalze,
• Fig. 4 eine Seitenansicht der Trennvorrichtung allein, und
• Fig. 5 eine teilweise geschnittene Frontansicht der Trennvorrichtung, wobei Teile der Trennvorrichtung weggebrochen wurden.

Further features and advantages of the invention result from the following description, which in connection with the accompanying drawings explains the invention using an exemplary embodiment. It shows

• 1 is a partially schematic perspective view of a writing mechanism with integrated push transport for a set of forms and a separating device assigned to the writing mechanism,
• 2 is a schematic representation of the translation gear for driving the platen of the writing mechanism and the thrust transport,
• 3 shows a schematic partial section through the writing mechanism with a separating device attached perpendicular to the axis of the platen roller,
• Fig. 4 is a side view of the separation device alone, and
• Fig. 5 is a partially sectioned front view of the separating device, parts of the separating device having been broken away.

1 shows a typewriter or printing unit, generally designated 10, with a machine frame 12, in which a platen roller 14 with its shaft 16 (FIGS. 2 and 3) is rotatably mounted. Parallel to the platen roller 14, a writing or printing head 18 can be moved back and forth in a manner known per se. The writing mechanism as such is known per se and is therefore not explained in detail.

An endless form set 20 (FIG. 3) is fed to the platen roller 14, which rotates around the platen roller 14 with a certain wrap angle and is labeled in a writing or printing area 22 by the print head 18, which can be moved transversely to the feed direction A of the continuous form set 20.

The endless form set 20 consists of several superimposed webs or layers and has a perforation on its two longitudinal edges. With this perforation for the transport of the continuous form set 20, a push transport cooperates, each of which comprises a spiked belt 24 for each perforation. The spiked straps are immediately in front of the platen roller 14, so that the form set 20 is pushed by the spiked straps 24 around the platen roller 14. The two spiked straps 24 are of identical design, so that only one is described with reference to FIG. 3.

The spiked belt 24 is formed by an endlessly revolving band, which is motor-driven via a drive shaft 26 and has on its outside a multiplicity of protruding spikes 28, the mutual spacing of which corresponds to that of the holes in the perforation of the form set 20.

The form set 20 runs into the push transport via a guide rod 30 upstream of the spine belt 24, the spikes 28 engaging in the holes in the perforation of the form set 20. For this purpose, the hold-down belt 24 is assigned a hold-down 32 with a guide surface 34, which is pivotally mounted in such a way that it can be tensioned against the toothed belt 24 by means of a spring 36 (FIG. 1), so that the set of forms 20 through the guide surface 34 against the drive belt 24 is pressed.

In the direction of travel A behind the guide surface 34, a pressure wheel 38 which can be driven synchronously with the spine belt 24 is rotatably mounted and has a plurality of cutouts 40 on its circumference, the mutual spacing of which in the circumferential direction of the pressure wheel 38 corresponds to the mutual spacing of the spikes 28. With the cutouts 40, the pressure wheel 38 engages over the spikes 28 and thus prevents the spikes 28 from slipping out of the perforation of the form set 20. The synchronous drive between the toothed belt 24 and the pressure wheel 38 is achieved in that a gear 42, which is connected to the drive shaft 26 of the toothed belt 24 in a rotationally fixed manner, meshes with a gear 44 seated on the shaft of the pressure wheel 38.

Since the outer webs of the form set 20 describe a larger path than the inner webs when wrapping around the platen roller 14, a reduction in the rotational speed between the platen roller 14 and the spike belt 24 is provided to avoid paper jams or tearing of the webs, which the platen roller 14 compared to the feed speed of the spine 24 rotates slightly faster. This results in a slight mutual displacement of the form set paths so that they lie flat on one another.

This coordination of the speeds of the spiked belt and the platen roller is achieved by a gear, which is shown schematically in FIG. 2. A gear 46 is connected in a rotationally fixed manner to the shaft 16 of the platen roller 14 and engages via an intermediate gear 48 with a gear 50 seated on the drive shaft 26 of the spiked belt 24. The drive of the spike belt 24 is thus derived from the platen roller 16.

The spine strap 24 is guided around a guide body 52 with a smooth support for the belt drum that is currently engaged with the perforation of the form set 20. The spines are formed by cylindrical or involute-shaped pins. The recesses 40 formed in the pressure wheel 38 are designed to be complementary to the shape of the pins or spikes 28, but are slightly larger in diameter than the spikes 28 in order to allow the spikes 28 to enter and exit the recesses 40 smoothly. The pressure wheel 38 is preferably made of plastic.

Between the spine 24 and the platen 14 and between the pressure wheel 38 and the platen 14 guide surfaces 54 are provided for guiding the form set from the spine 24 around the platen 14 to the writing area 22, with these guide surfaces 54 being the relatively short bridging path between the spikes 24 and the platen roller jacket closed will.

In the form set direction A, pressure rollers 56, 58 are assigned in front of and behind the writing area 22 of the platen roller 14, which hold the form set 20 against the peripheral surface of the platen roller 14. A height-adjustable guide plate 60 is arranged below the platen roller 14, which can be adjusted between the position shown in solid lines in FIG. 3 and the position represented by dash-dotted lines. In the upper position, the guide plate 60 ensures that the leading end of the form set 20 runs in automatically between the platen roller 14 and the upper pressure roller 58.

In the direction of passage A, behind the platen roller 14, there is a support surface 62, which, however, is only used when the typewriter works without a separating device.

For the automatic operation of the writing mechanism 10, a separation device, generally designated 64, is assigned to it, which forms an independent unit and can be arranged directly above the writing roller 14, as is shown in FIG. 3.

The separating device 64 comprises a bearing frame with two lateral bearing plates or bearing cheeks 66, which are connected to one another by a cutter bar 68. At its lower end, each end shield 66 has a tong-shaped gripper with a fixed leg 70 and a movable leg 72. The movable leg 72 is pivotally mounted on the end shield 66 about an axis 74 (FIG. 4) and is tensioned by a spring 76 in the direction of the fixed leg 70. The two legs of the gripper have circular recesses with a radius corresponding to the radius of the platen roller shaft 16. The separating device is placed on the platen roller shaft 16 from above, the movable gripper leg 72 being deflected and snapping behind the platen roller shaft 16 under the action of the tension spring 76, so that the two grippers under the action of the tension springs 76 firmly hold the separating device 64 on the platen roller shaft Hold 16. By pivoting the movable gripper legs 72, the separating device 64 can be removed from the writing mechanism at any time.

The knife bar 68 carries a stationary but resilient knife 78 with a straight cutting edge (FIG. 3). This fixed knife 78 is assigned a rotary knife, generally designated 80, which is rotatably supported by a shaft 82 in the two end plates 66. The rotary knife 80 consists of a hollow cylinder which has two diametrically opposite openings 84, 86, which extend at least over a length of the rotary knife 80 corresponding to the width of the form set path 20 and define a passage for the form set path 20 through the rotary knife 80, such as this can be seen in FIG. 3. Thus, with the exception of the two closed cylindrical sections at the two ends of the rotary knife 80, only two elongated jacket sections 88 and 90 remain (see FIGS. 3 and 5). The edge of the casing section 88 delimiting the opening 86 is designed as a spirally curved cutting edge 92 which, when the rotary knife 80 rotates counterclockwise as viewed in FIG. 3, interacts with the cutting edge of the stationary knife 78 to shear off the form set web 20.

The knife 80, which can be rotated in both directions, is driven by a drive motor 94 which is flanged to a bearing plate 66. Here, a pinion 98 seated on the motor output shaft 96 drives a gearwheel 100, which is connected in a rotationally fixed manner to a shaft 102 which runs parallel to the rotary knife 80 and extends over the entire length of the separating device 64 and is supported in both end shields 66. The shaft 102 carries in the region of the ends of the rotary knife 80 a pinion 104, which meshes with a gear 106 connected to the rotary knife 80 at the respective end of the rotary knife. This makes it possible to drive the rotary knife 80 synchronously at its two ends in order to prevent the rotary knife 80 from twisting about its longitudinal axis, which would otherwise be possible due to the large openings 84 and 86 in the hollow cylinder.

Control surfaces 108 (only one of which is visible in FIG. 5) are formed on the end of the shaft 82 of the rotary knife 80 remote from the motor, which interact with limit switches 110 or the like in order to determine the direction of rotation of the drive motor 94.

In the direction of passage A, behind the rotary knife 80, a take-off roller 112 is arranged, which is directed parallel to the rotary knife and is rotatably mounted with its shaft 114 in the end shields 66. The take-off roller 112 is also driven by the drive motor 94. For this purpose, a first pulley 116 is rotatably connected to the output shaft 96 of the drive motor 94, which drives a pulley 120 seated on the shaft 114 of the take-off roller 112 via a crossed belt 118. In this case, a freewheel is built into the pulleys 120, which allows torque transmission from the drive motor 94 to the take-off roller 112 only when the drive motor 94 rotates the rotary knife 80 back to its starting position, ie viewed clockwise in FIG. 3, after the cutting process has ended. In contrast, the freewheel ensures that the take-off roller stands still when the drive motor 94 drives the rotary knife 80 during the cutting process. This ensures that a pull from the take-off roller 112 is only exerted on the section of the form set web 20 to be cut off when this section is completely separated from the form set web 20. When suddenly turning back the rotation knife 80 in its starting position and the simultaneous jerky drive of the take-off roller 112, the separated form set section lying loosely on the surface of the take-off roller 112 is then flung out of the separating device 64. In order to ensure good friction between the take-off roller 112 and the form set section resting on it, rings 122 made of rubber or another suitable material with a high coefficient of friction are arranged on the take-off roller 112 at axial intervals.

In order to enable the leading end of the form set path to be carried out automatically by the rotary knife 80 after a separating process, a guide plate 124 which is parallel to the axis and extends over the length of the openings 84, 86 and which leads the leading end of the form set path 20 to the opening is arranged in the rotary knife 80 84 leads and cooperates with a guide grid 126 which is pivotally mounted on the two bearing plates 66 about an axis 128 and extends from the opening 84 of the rotary knife 80 to above the take-off roller 112.

It can be seen that the separating device is very compact in its construction and enables the cutting of wide and narrow form set paths. Despite its large diameter, the rotary knife can be accelerated very high due to its small mass, so that the separation process can be carried out very quickly in adaptation to the high writing speeds of modern writing mechanisms. The cut-off part of the form set is held by the rotary knife 80 until it has been removed from the separating device 64 by the take-off roller 112.

It should also be added that the rotary knife in the separating device has been omitted in FIG. 1 for greater clarity.

Claims (9)

1. A means in typing and printing mechanis- mus for cutting sections of sheet-like recording media (20), comprising a stationary knife (78) extending across the width of said recording medium (20) and a rotary knife (80) interacting with said knife (78) and being rotatable to and fro by a drive means about a knife axis (82) which is parallel to said stationary knife (78), said rotary knife (80) having a cutting edge (92) extending angularly with respect to said knife axis,a take-up roller (112) being rotatably supported in feed direction behind said rotary knife (80) and parallel thereto, said take-up roller intermittently acting onto said recording medium (20) such that said take-up roller is out of operation during the cutting movement of said rotary knife (80) and removes the cut-off sheet section during the backward rotation of said rotary knife (80), characterized in that said rotary knife (80) located behind the recording position when regarded in feed direction of said recording medium (20) is formed by a hollow cylinder, the jacket (2) of said hollow cylinder having diametrically opposed perforations (84, 86) extending along a lengthwise extent of said hollow cylinder corresponding to the sheet width and forming an opening for the passage of said recording medium (20), one of said perforations being defined on one longitudinal side by a spiral cutting edge (92), and further characterized in that said stationary knife (78), said rotary knife (80) and said take-up roller (112) are located within a frame which is releasably connectable to said typing mechanism (10), said frame carrying a drive motor (94) driving said rotary knife (80) and said take-up roller (112) throuh a gear means.

2. A cutting means as set forth in claim 1, characterized in that said frame comprises two bearing plates (66) rotatably supporting said rotary knife (80) and said take-up roller (112) and being connected to each other by a beam (68) carrying said stationary knife (78).

3. A cutting means as set forth in claim 1 or 2, characterized in that each bearing plate (66) has gripping means (70, 72) biased in their closing position, said gripping means being adapted to releasably fasten said cutting means (64) to the shaft (16) of the platen (14) of said typing and printing mechanism (10).

4. A cutting means as set forth in any of claims 1 to 3, characterized in that said motor is fixed to one of said bearing plates (66) and drives through a gear drive means (98, 100) a shaft (102) supported by both bearing plates (66) and directed parallel to said rotary knife (80), said shaft being in driving connection with said rotary knife (80) through a gear drive means (104, 106) each provided at the longitudinal end portions of said rotary knife (80).

5. A Cutting means as set forth in any of claims 1 to 4, characterized in that the shaft (82) of said rotary knife (80) has control surfaces (108) which interact with microswitches (110) associated to said shaft (82) so as to control said drive motor (94).

6. A cutting means as set forth in any of claims 1 to 5, characterized in that an idle running gear is provided in the gear connection between said drive motor (94) and said take-up roller (112) such that a torque transmission from said drive motor (94) to said take-up roller (112) is avoided during the cutting operation.

7. A cutting means as set forth in claim 6, characterized in that a belt pulley (116, 120 respectively) is provided on each the shaft (96) of said drive motor (94) and the shaft (114) of said take-up roller (112), a crossed belt running around the pulleys (116, 120) and further characterized in that said idle running gear is provided in one of said belt pulleys (116,120).

8. A cutting means as set forth in any of claims 1 to 7, wherein a guide face (124) extending along the lengthwise extent of said perforations and leading to the outlet end of said opening is provided within said hollow rotary knife (80), characterized in that a guide element (126) swiveling between said bearing plates (66) about an axis (128) which is parallel 'to the knife axis is associated to said guide face (124), said guide element projecting with its one longitudinal edge into said rotary knife (80) and extending up to a point above said take-up roller (112).

9. A cutting means as set forth in any of claims 1 to 8, characterized in that said take-up roller (112) is provided at least along a part of its circumferential face with a coating (122) having a high coefficient of friction.

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