CA1228799A - Cutting edge correction - Google Patents

Abstract

Abstract Given the method, the pairs of circular knives (4,5) of a longitudinal cutter apparatus are displaced on rails (7) proceeding transversely relative to the web, being displaced thereon by prescribable positioning distances from an outer, apparatus-fixed bench mark up to a carriage-fixed bench mark. In order to be able to take the alterred position of the cutting edge (19) which may have arisen under given circumstances due to re-grinding into consideration, the distance of the cutting edge (19) from an edge (69) fixed to the carriage of a circular knife is measured by means of position sensors (80) and is input into the control as part of the positioning distances. The carriage (6) is thereby po-sitioned at a different location such that the cutting edge (19) again lies at the proper location despite the re-grinding.

Description

'7991 METHOD FOR CONTROLLING THE POSITION OF THE CUTTING EDGES AT A LONG-TUDINAL CUTTER MEANS FOR WEBS OF PAPER AND THE LIKE AS WELL AS
CORRESPONDING LONGITUDINAL CUTTER APPARATUS
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The invention relates to a method of the type corresponding to the preamble of claim 1 and also relates to a corresponding longitudinal cutter apparatus.

Such a method and such a longitudinal cutter apparatus are known from the German Letters Patent 21 42 117. The carriages with the circular knives are thereby shifted by the conveyor means into predetermined positions which correspond to the desired width of the sub-webs to be produced from a wide paper roll. As long as the position of the cutting edges of the circular knives remains invariable relative to the carriage, this positioning can be arbitrarily repeated and the widths of the sub-webs can be set with the tolerance given by the working precision of the conveyor means.

The circular knives, however, must be reground from time to time since the stress and the wear due to the paper webs passing through with speeds up to 2500 meters per minute are considerable. This is particularly true for the driven, so-called ledger [or: bottom] blade which is de-signed pot-like, whereby the shearing interaction with the flat, so-called top cutter occurs at the end face of the edge of the pot. During regrounding, this pot edge is ground off so that the pot becomes "lower".
It can thereby definitely be a matter of amounts of 1 to 2 mm.

When the positioning is restricted to bringing the carriages to a spew cilia location and the position of the cutting edge relative to the carriage has changed, this dislocation enters into the width of the sub-webs produced, these thus deviating from their rated dimension by corresponding amounts.

This is inadmissible in many instances. It is known to compensate the change in the position of the cutting edges due to the grinding with shims. This method wastes time and is subject to error because the needed shims must be determined by means of measurements to be undertaken at every pair of blades and errors due to tolerances remain.
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The object of the invention is to create a method and a longitudinal cutter apparatus wherein a positioning of the cutting edges at the Sue-cuter knives is possible even after a regrinding thereof in a simpler fashion without shims and, nonetheless, with greater reliability.

This object is achieved in terms of its methodological aspect by means of the features recited in the characterizing part of claim 1.

As in the known embodiment, the positioning of the carriages thus ensues by means of setting the interval between an outer, apparatus-fixed bench mark and a carriage-fixed bench mark. The position of the cutting edge changed by the regrinding, however, is acquired by means of a measure-mint and taken into consideration in the control, so that the carriage is not placed at a different position such that the position of the cutting edge again assumes its rated position and the width of the sub-webs produced is not influenced by the regrinding.

This all ensues by means of a measurement given [a] position of the cutting edge changed after the regrinding, so that errors as can occur in the selection of the correct shims and tolerances that may arise no longer play any part.

The inventive solution of the object in terms of its apparatus-related aspect is reflected in claim 2.

A simple formation of the carriage-fixed bench mark which is easy to acquire by means of external measuring devices can, in accord with claim 3, be given by means of an edge at the carriage which, in accord with claim I, can be formed by a special measuring piece.

In the embodiment of claim 5, the measuring means comprises outer, stayshunner position sensors past which both the edge of the reground air-cuter knives as well as the edge at the measuring piece forming the carriage-fixed bench mark travel and generate pulses when a blade carriage is displaced. These pulses can be employed for deeming the spacing [between] the two said edges.

All embodiments known from the Prior Art for this purpose come into con-side ration as position sensors, for example inductive or magnetic sensors, micro switches mechanically actuated by the edges, photoelectric and pneumatic sensors, etc.

After the blades have been built in, the distance of the cutting edge of the reground (or new) ledge [or: bottom] blade from the edge forming :.` ' 'it , ,, , ' ~lZ~79~
the carriage-fixed bench mark is determined at every pair of blade carriages in an operating cycle preceding the positioning in that the blade carriages are conducted past the position sensors respectively intended for them.

The problem thereby arises that the control must be able to unequivocalallocate the pulses arising when passing the cutting edge and the measuring edge to a specify pair of blade carriages.

The feature of claim 6 serves this purpose. It enables the pulses of the different pairs of blade carriages to be separated from one another. The blade carriages are entrained along the rails by the conveyor means. On the basis of the specified design, the pairs of blade carriages do not reach the allocated position sensors simultaneously but at specific in-tervals. In this fashion, the signals of the individual position sensors can be separated from one another and be allocated respectively to a spew cilia pair of blade carriages. The signals which appear in a defined displacement range of the conveyor means can only derive from a defined pair of blade carriages.

It is most expedient to have the intervals increase by identical amounts in accord with claim 7.

An exemplary embodiment of the invention is schematically illustrated in the drawing.

JIG 1 shows a vertical longitudinal section through the essential part of the apparatus;
FIG 2 shows an elevation according to FIG 1 from above, partially in section and given omission of the upper deflection drum;
FIG 3 shows a schematic view of the conveyor means;
FIG 4 shows a side view of a single ledger or: bottom] blade carriage;
FIG 5 shows a view according to FIG 4 from the left with an additionally indicated position sensor;
FIGS 6 and 7 show schematic sectional views of the locking means con-twined in the blade carriage;
FIG 8 shows a single blade pair emphasized in enlarged scale;
JIGS 9 through 11 show an enlargement of the region in FIG 8 indicated with dot-dash lines given various regrinding conditions of the ledger [or: bottom] blade;
FIG 12 is a schematic illustration of the pulses for the control of the conveyor means.

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the paper web 1 runs butter two deflection drums [or: rollers] 2,3 which en- seated in the machine frame M, running vertically in the indicated direction through the apparatus and being longitudinally cut there. The supply reel and the sub-reels onto which the sub-webs produced by the longitudinal cuts are rewound are not shown.

The division of the web ensues by means of interacting circular knives,namely the so-called ledger [or: bottom] blade 4 and the top cutter 5.
The ledger [or: bottom] blade 4 is seated at a ledger [or: bottom] blade carriage referenced 6 overall which is guided at a rail connected to the machine frame M and extending transversely across the web width.
A conveyor rod 8 is displaceable in longitudinal direction in the rail 7, the ledger [or: bottom] blade carriage 6 being connectable as desired to said conveyor rod 8 in order to displace it along the rail 7 into a desired position which corresponds to the location of the cut in the web 1. The design of the ledger [or: bottom] blade carriage 6 shall be explained in greater detail with reference to FIGS 4 through 7.

The ledger [or: bottom] blade 4 is driven in the indicated sense, whereas the top cutter 5 does not have a drive but is merely loosely entrained.
It is seated at the top cutter carriage referenced overall with 9 which, just like the ledger [or: bottom] blade carriage 6, is displaceable by a conveyor rod 10 along a rail 11 secured to the machine frame M which extends transversely across the web width. A pneumatic piston/cylinder unit issue disposed on the ledger [or: bottom blade carriage 12, the piston 13 thereof being extendible perpendicular to the web 1 against the ledger [or: bottom] blade carriage 6 against the action of a spring 14. Seated at the front end of the piston rod 15 is a further piston/
cylinder unit 16 who's axis extends parallel to the axis of the ledger [or: bottom] blade 4 and whose piston is displaceable such against the action of a spring 18 that the top cutter 5 is upwardly entrained act cording to FIG 2.

The piston cylinder unit 12 serves for the control of the adjustment ofthe top cutter 5 against the ledger [or: bottom] blade 4 [and] the piston/
cylinder unit 16 [serves] for producing the seating of the top cutter 5 against the end edge 19 of the ledger [or: bottom] blade 4 which forms the cutting edge, whereby a prescribed cutting pressure is observed. The control ensues by means of a solenoid valve 20 allocated to every top cutter carriage 9, said solenoid valve, when actuated, allowing come pressed air from the feed line 21 to proceed via the line 22 behind the piston 13 of the piston/cylinder unit 12, whereby the top cutter 5 act coding to PIG 1 is displaced toward the right. When the displacement has been carried out, the channel 23 formed in the piston 13 and in the ' .'' :. :'' :. .', 'I' ,:,'~' piston rod 15 comes into communication with the compressed air feed line 22 and the piston/cylinder unit 16 receives compressed air so that the top cutter 5 is drawn against the end face 19 of the ledger [or:
bottom] blade 4. The actuation thus ensues in a sequence which prevents the top cutter 5 from striking against the circumference of the ledger [or: bottom] blade 4.

The solenoid valve 30 which is allocated to every blade pair 4,5 or, respectively, to every carriage pair 6,9 serves for the initiation of the locking or, respectively, unlocking of the carriages 6,9 at the appertaining rails 7,11. The compressed air is advanced via the line 26.
The locking and unlocking means explained in yet greater detail in con-junction with FIGS 6 and 7 is of such a nature that it either releases the carriages 6,9 at the rails 7,11 and simultaneously couples with the conveyor rod 8,11 [sic] or uncouples therefrom and locks to the rails 7,11. The actuation of the locking and unlocking fixture occurs by means of the solenoid valve 30 via the lines 27,28 simultaneously at the carriages 6,9, so that both carriages 6,9 can be simultaneously moved.

Numbers of carriages 6,9 allocated to one another are respectively present corresponding to the number of longitudinal divisions] of the paper web 1 that are desired. In the schematic illustration of the conveyor means of FIG 3 which is referenced 40 overall, five pairs of carriages are pro-voided, whereby the top cutter carriages 9 are merely indicated by means of the locking and unlocking fixtures 50 and the top cutters 5.

The conveyor rods 8,10 are displaced in longitudinal direction by a motor operator 41 via worm gearings 42 and ball caster spindles 43. The worm gearings 42 of both conveyor rods 8,10 are connected to one another via an articulated shaft 44, so that the conveyor rods 8,10 and, thus, the carriages 6,9 are always displaced by identical amounts a the rails 7,11 (FIG 1).

A pulse generator 45 which resolves the transport motion of the conveyor rod 8 into discrete pulses is situated at the worm gearing 42 ox the conveyor rod 8 for the ledger [or: bottom] blade 4. Every counted pulse thus corresponds to a specific transport path of the blades.

At the beginning of the positioning, the conveyor rod 8 is pulled back against a Nero dead stop which represents an apparatus-fixed bench mark.
The carriages 6 are thereby situated in their starting position which are established by the spacing of index bores 47 in the conveyor rod 8.
The cogs of the locking and unlocking fixtures 50 engage into these index bores 47, the design of said fixtures still to be explained in - .: :,. : ::::
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detail with reference to FIGS 6 and 7. no their starting position, however, the carriages are uncoupled from the conveyor rod 8 and are fixed to their rail 7. When, for example, the first carriage from the loft according to FIG 3 is to be brought into a specific position, then it is uncoupled from the rail 7 and coupled to the conveyor rod 8 by means of engagement into the appertaining index bore 47 of the conveyor rod 8. The motor operator 41 is then actuated until, proceeding from the seating against the zero dead stop 46, a specific plurality of pulses of the pulse generator 45 has been traversed and the conveyor rod 8 has covered a corresponding distance. The carriage 6 has then reached its desired position and is uncoupled from the conveyor rod 8 and coupled to the rail 7. This procedure is executed such for all carriages 6 that the conveyor rod 8 executes only a single stroke for the positioning of all carriages 6. All carriages 6 are coupled on in the starting position and are "left standing" in their preselected rated position during the stroke.

The respective top cutters 5 at the carriages 9 are thereby also en-trained, so that these are also situated in their new positions ready for interaction with the ledger [or: bottom blades 4.

As may be seen from FIGS 4 and 5, the ledger [or: bottom] blade carriage 6 comprises a motor carrier 29 which [in turn] comprises a hose plate 31 extending parallel to the front of the rail 7 as well as a supporting plate 32 perpendicular thereto and to the supporting rail 7, these being additionally connected to one another by means of reinforcing angles 33.
The blade motor 35 is secured to the supporting plate 32 via screws 34.

At its front side distanced from the machine frame M, the rail 7 comprises, according to FIG 5, a circular cross-section guide rod 36 disposed at the right outside of the rail 7 and extending over the entire length thereof, a ball-type nipple 37 which is disposed in a cleat 38 at the underside of the base plate 31 being seated in said ball-type nipple.
A guide strip 39 projects at the opposite side, i.e. toward the left in FIG 5, a roller 51 pressing against the underside thereof, said roller 51 being seated in a carrying member 52 which is likewise secured to the underside of the base plate 31.

The carriage 6 is thus guided in longitudinal direction at the guide rod 36 and is supported against a rotation in accord with FIG 5 toward the right by means ox thy roller 51. So that the carriage 6, however, while rotating toward the left, does not lie against the front side of the rail 7 and drag along it, a further roller 54 is provided a a pedestal 53, said further roller 54 running on the front side of the conveyor :, $

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rail 7 and [being seated in part at the same time in front of the con-voyeur rod 8 disposed in the rail 7 which is longitudinally displaceable relative thereto and retaining said conveyor rod 8 in the recess 55 of the rail 7.

The locking and unlocking fixture referenced 50 overall is secured to the base plate 31, said fixture 50 being designed as a piston/cylinder unit comprising a cylinder 60 and a piston I comprising piston rods 61,61 protruding toward both sides. Two cylinder chambers 57,58 are formed in the cylinder 60 at opposite sides of the piston 56. The cylinder chamber 58 is outwardly limited by a piston 63 likewise guided in the cylinder 60 and penetrated by the piston rod 62 and carries a friction lining 64 at its front side which can lie against the front side of the rail 7.

The solenoid valve 30 already mentioned with reference to FIG 1 is a two-position valve via which a compressed air source 59 is selectively connectable to the cylinder chambers 57,58. In the position of FIG 6, the cylinder chamber 57 is connected and the piston 56 is pressed down, so that the index cog 65 engages into the index bore 66 of the conveyor rod 8. The locking and unlocking fixture 50 is connected to the conveyor rod 8 in this fashion and is entrained by the latter when it moves, so that the entire carriage 6 is correspondingly displaced.

In the position of FIG 7, the cylinder chamber 58 is connected to the compressed air source 9 and the piston 56 is pressed up. Simultaneously, the piston 63 is pressed down and presses the friction lining 64 against the front side of the rail 7. The roller 51 is supported against these forces. In this operating condition, the carriage 6 is fixed against the rail 7 via the friction lining So and the index cog 65 is released from the conveyor rail 8.

Governing different positions of the cutting edge 19 at a specific carriage 6 shall now be explained with reference to FIGS 8 through 12.
A pair of blades 4,5 has again been shown in FIG 8, whereby the cutting edge 19 is formed by the end face of the ledger [or: bottom] blade 4.
A measuring piece 67 is attached to the supporting plate 32 of the carriage 6, whereby the radial distance 68 of the outside surface from the axis of the ledger ion: bottom blade 4 is identical to the radius thereof. A reference edge whose position corresponds to the position of the cutting edge 19 is fashioned at what is the right-hand lateral face of the measuring piece 67 according to FIG 8.

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I to As derives from FIG 9, the CUttillg edge I and the reference edge 69 have a specific distance 70 from Qn2 another given a new ledger [or-bottom] blade 4.

When the ledger ion: bottom] blade 4 has then be reground, the distance72 between the edges 19,69 has become smaller by the amount 71 that has been ground off, as may be seen from FIG 10. The ground-off thickness 71 has been shown with exaggeration in FIG 10; in reality, it is a matter of amounts on the order of 1 to 2 mm.

In the condition. according to FIG 10, thus, the position of the cutting edge 19 relative to the reference edge 69 or, respectively, the carriage 6 has become different overall. If the carriage 6 were thus to be post-toned at the same location, the cut in the paper web would occur at a location which is wrong by the amount 71.

In order to prevent this, the amount 71 is automatically incorporated into the control. To this end, position sensors 80 which emit an elect tribal signal when they are reached or passed by the edges 19 or, resee-lively, 69 are provided right outside of the ledger [or: bottom blade 4 or, respectively, the measuring piece 80~ In the fashion to be seen from FIG 5, the position sensors 80 are attached immediately outside of the measuring piece 67, being attached stationary in the apparatus to a strip 87 proceeding continuously across the web width which is disposed on supports 86.

When, thus, the ledger [or: bottom blades 4 have been replaced or no-ground and have also been remounted on the carriages 6, the carriages 6 are conducted past the position sensors 80 in the direction proceeding from left to right in FIG 8. The signal 73 (19) shown at the top in FIG 12 thereby arises in the position sensor 80 when the cutting edge 19 passes and the signal 74 (69) arises when the reference edge 69 passes.
The signals are supplied via the line 75 to the microprocessor controller 100 of the apparatus. At the some time, the microprocessor controller 100 receives the signals of the pulse generator 45 at the drive of the con-voyeur rod 8 via the line 48. These signals are schematically indicated in the center in FIG 12 and are referenced 76. The pulse 73 (19~ now places a counter unit in the microprocessor controller 100 in operation, this being in turn shut off by the second pulse 74 (69~ and counting the pulse set 77 shown at the bottom in FIG 12 there between. The pulse sex 77 deriving upon initial installation of the apparatus is stored in the microproce son controller 100 for each and every carriage 6. After a no-placement or, respectively, a regrinding of the ledger [or: bottom]
blades 4, the pulse set 77 then deriving is again counted and compared ~L22~ 3 to the original pulse set 77. A deviation in the number of pulses corresponding to the distance 71 then derives, this being automatically input into the control of the motor operator Al. The motor operator 41 then does not position a specific carriage 6 in its original position which corresponds to FIG 9 and which would yield the deviation 71 of the position of the cutting edge lo from the desired cut line 90, but is positioned in the position shown in FIG if in which the cutting edge lo is again placed on the desired cut line 90.

The correction of the position of the cutting edge lo ensues automatically.
In order for the microprocessor controller lo to distinguish between the pulses referenced 73(19) and 74(69) in FIG 12 which axis when passing the position sensors 80 allocated to each and every carriage 6, the position sensors 6 are not all identically positioned relative to the carriages 6 in terms of their control-oriented initial positions but, as may be seen from JIG 3, are offset from the reference edge 69 of each and every carriage by the distances 81, By, ...85 toward the right, the distance 82 thereof being greater by a defined amount than the distance 81, the distance 83 being greater by the same amount than the distance 82, etc. When, thus, all carriages 6 are coupled to the conveyor rod 8 and this is steadily displaced toward the right in accord with FIG l, the pulses of the individual position sensors 80 successively arrive in the controller lo and do not overlap, so that the controller can allocate the various pulses to unequivocally defined carriages 6.

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Claims (10)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. In a method of positioning cutting edges of a pair of circular cutting blades of a longitudinal cutting device for webs of paper and the like, said cutting device having a frame with a pair of rails on each side of the web extending transverse to the direction of movement of the web, each of the pair of blades being mounted in a carriage releasably secured to the rails and transport means for moving the carriages along the rails to obtain the desired position from a bench mark on the frame of the device, the method including shifting each of the carriages for the blades a predetermined distance from the bench mark to obtain a fixed position of the coacting cutting edges from the bench mark and then locking the carriages in said position, the improvements comprising measuring the distance of the cutting edge of one blade from a bench mark of its carriage and using this distance to modify the predetermined distance of movement for the carriage to compensate for variations in the width of the one blade.

2. In a method according to claim 1, wherein the step of using the distance to modify the predetermined distance includes comparing the recently measured distance to a standard distance to obtain an offset, and utilizing the offset to vary the predetermined distance of movement for the carriage.

3. In an apparatus for longitudinally slitting and cutting a web of material, said apparatus having a pair of rails mounted on a frame on each side of the web to extend transversely to the direction of movement of said web; a bench mark on the frame; at least one cutting unit, each cutting unit having a first circular cutting blade and a second circular cutting blade with coacting cutting edges, a first carriage for mounting the first blade for rotation and being secured to one of the pair of rails and a second carriage mounting the second blade for rotation and being secured to the other rail of the pair of rails; and transport means for moving both the first and second carriages of each unit along their respective rails to position the coacting cutting edges a predeter-mined distance from the bench mark, the improvements comprising means for compensating for different axial thicknesses of the first cutting blade including a carriage bench mark on each first carriage, means for measuring the axial distance between the carriage bench mark and the cutting edge of the first blade and means for adjusting the distance of displacement of the first and second carriages by the transport means in response to changes in the axial distance to obtain the predetermined distance of the coacting cutting edges from the bench mark of the frame.

4. In an apparatus according to claim 3, wherein the carriage bench mark is formed by a reference edge on said first carriage.

5. In an apparatus according to claim 4, wherein the first carriage has a motor carrier for a motor to rotate the first blade, and wherein said reference edge is a measuring piece secured to the motor carrier of said first carriage, said measuring piece having the same distance from an axis of the first blade as the periphery of said blade.

6. In an apparatus according to claim 5, wherein the means for measuring the axial distance comprises a sensor stationarily disposed on a frame of the apparatus along a path of movement of the first carriage on said rail, said sensor emitting an electric signal as the cutting edge of the first blade and as the reference edge of the first carriage move thereby.

7. In an apparatus according to claim 6 having at least two cutting units each having a sensor for creating an electrical pulse when the cutting edge and reference edge of the carriage passes thereby, said sensors being mounted different distances on the frame so that with the carriages all positioned on the transport means and the transport means in its initial starting position, the edges of each carriage pass below its sensor at a different point of transport to enable a control means of the apparatus to separate the electrical pulses for each carriage and allocate them to the respective carriage.

8. In an apparatus according to claim 7, wherein the difference in the distance of travel for each carriage is an identical amount so that the pulses from the sensors are received in sequence as the trans-port means moves the carriages beneath their respective sensor.

9. In an apparatus according to claim 3, wherein the means for measuring includes a sensor mounted on the frame in the path of the first carriage being moved by the transport means, said sensor creating an electrical signal when the cutting edge of the first blade passes therebelow and when the bench mark on the first carriage passes thereby, said means for measuring including a pulse generator attached to the transport means for creating a plurality of pulses as the transport means moves the carriages from an initial position and a counter for receiving the pulses of the pulse generator said first of the electrical signals from the sensor starting the counter to count the pulses from the pulse generator and the second signal terminating the counting with the number of counted pulses determining the distance between the cutting edge and the bench mark of the carriage.

10. In an apparatus according to claim 9, wherein the means for adjusting determines the changes in the axial distance by comparing the counted pulses for the blade against a standard to create an error signal and uses the error signal to adjust the distance of displacement of the first and second carriages by the transport means from the bench mark of the frame.