SE444282B - SCREW MACHINE FOR PAPER COATS WITH CONTROL DEVICE FOR SYNCHRONIZING A MOTOR DRIVE CUTTING PLATE CUTTING PLATE AND MOTOR DRIVE COATING ROLLS - Google Patents

Description

vrïïffåë so 81 a Ä The invention is described in more detail below with reference to the accompanying drawing.

Pig. 1 is a perspective view of the entire cutting machine according to the invention. V Pig. 2 is an enlarged front view of the screen mechanism.

Pig. 3 is a similar view of a variant of the screen mechanism.

Pig. 4 is a block diagram of a first embodiment of the control unit according to the invention.

Pig. 5 is a block diagram of a second embodiment thereof.

Pig. 6 is a block diagram of a third embodiment of the control unit according to the invention.

According to Figs. 1 and 2, a moving web 1 is cut into blanks by means of a cutting unit denoted by 2 in general.

The cutting unit 2 comprises a knife blade 3 and a base 4, which are located opposite each other and between which the web 1 is fed, and a mechanism S with gears and crank arms for interlocking the knife blade 3 with the base 4. Upstream of the cutting unit 2 there are a pair feed rollers 6 for feeding the web 1 in the direction of the cutting unit 2.

The cutting unit 2 is now described in detail. There are two pairs of driven shafts 7a, 7b and Ba, 8b, so are separated from each other and of which the shafts 7a, 8a are located above the web and the shafts 7b, 8b below it. The main gears 9a, 9b are fixedly mounted on the ends of the driven shafts 7a, 7b, while driven gears 10a, 10b are fixedly mounted on the ends of the driven shafts 8a, 8b. Similarly, driving gears 12 are attached to the ends of a driving shaft 11. The driving gears 12 engage the upper gears 9a, 10a, which engage each of the lower gears 29b, 10b.

Crank arms 13a, 13b, 14a, 14b are mounted on the ends of each of the shafts 7a, 7b, 8a, 8b. Knife blade 3 and under- mi. The 'sin-nja' layer 4 is pivotally mounted at one end of each of the crank arms 1a and 13b by means of pins 15. At its other end, the blade and the substrate are each provided with a guide slot 16, which extends axially for receiving a slide 17, which is pivotally mounted by means of a pin 15 on the respective crank arm 14a (14b). The upper surface of the base 4 facing the knife blade 3 is curved. The crank arms are set in such a way that the crank arms 13a, 13b will not move in phase with the crank arms 14a, 14b. As the shafts 7a, 7b, 8a, Bb rotate, the point at which the blade 3 is in contact with the substrate 4 is moved from one end to the other end for cutting the web 1.

A first motor 18 for driving the cutting unit 2 is connected to the driving shaft 11. To the first motor 18 a pulse generator PGA is connected for generating a pulse signal 4%, which is proportional to the angle of rotation of the first motor, together with a roof generator 19 for generating a voltage VF, which is proportional to the speed of the first motor .

The feed rollers 6 are driven by a second motor 21 via speed-changing gears 20. The motor 21 is similarly connected to a pulse generator PGB for generating a pulse signal 4%, which is proportional to the angle of rotation of the motor 21, and to a roof generator 22 for generating a voltage VF, which is proportional to the motor 21 speed.

In the vicinity of the cutting unit 2 a sensor 23 is arranged, which senses the crank arm 13a and emits a detection signal, each time the cutting unit 2 has completed cutting. The sensor 23 can be of photoelectric, magnetic or any other type.

Pig; 3 shows another example of the cutting unit 2.

The substrate 4 is supported on sliding elements 24 such as rollers. A rod 26 is pivotally mounted at one end on a pin 25 which is attached to a stationary part such as a machine frame (not shown). The rod 26 is provided with a slot 26a at its other end and with a further slot 26b in the middle of its length. , .. u ȃ xx .. in; .v, -. -. A pin 27 attached to the base 4 slidably fits into the slot 26a, while a pin 28, which is attached to the gear wheel 9b at an eccentric position, slidably fits into the slot 26b.

As the driving shaft 11 rotates, the substrate 4 will move back and forth, so that the point of contact between the blade 3 and the substrate 4 will move from one end to the other for cutting the web 1.

A first embodiment of the control coupling will be described below with reference to Fig. 4. It is intended to control the motor 21 for the feed rollers 6 in such a way that these are driven synchronously with the cutting unit 2.

Depending on a cut-off signal from the sensor 23, values Lo and Bo, which are set in a setting step 31, are fed to a calculation unit 32, which also receives the pulse signal tower PGB and performs the calculation Bo-Lo-4ä + Ûë. The result M of the calculation in the form of a digital signal from the calculation unit 32 is converted into an analog error signal VC by means of a digital / analog converter 33. The value Lo is a value which is proportional to the length to which the web is to be cut, while Bo is a value, which is proportional to the number of revolutions of the first engine 18, i.e. the distance over which the tip of the crank arm 13a is moved during a working process of the cutting unit 2.

A frequency / voltage converter 34 then converts the pulse signal to a reference voltage VA, which is proportional to the frequency of the pulse signal Ck. An operational amplifier 35 receives the reference voltage VA and the error voltage VC and outputs a difference (difference) voltage V0 (= A-VC) between 52553 SPå fifl ï fl9fl f-V. Depending on an cut-off signal from the sensor 23, a value Co counter 36, which subtracts the pulse signal Qš from Co. The count result- N (= Co-Qš) is output as a digital signal. The value Co is a preset value which is proportional to the angle over which the feed rollers 6 are rotated during the period from the end of the notch to its stop. The value Co is determined in such a way that the load on the motor is reduced to a minimum. The value N is applied to a digital / analog converter 37, which emits a stop voltage VB. The latter is set to a value which is equal to or greater than the maximum value of the reference voltage VA, when the cut-off signal occurs.

The stop voltage VB is limited in an input selector 38 by means of the reference voltage VA to obtain a limited voltage VD, which is the smaller voltage of the reference voltage VA and the stop voltage VB. The input selector 38 selects and outputs the higher voltage of the limited voltage VD and the difference voltage Vo. A speed command unit 39 compares the voltage VE from the input selector 38 with a feedback voltage VF from the roof generator 22 and adds or subtracts any difference between them to or from the VE for controlling the motor 21 of the feed rollers 6 via a motor control unit 40.

The first embodiment of the control clutch described above operates in the following manner.

When the sensor 23 emits a cut-off signal at or after completion of cutting, the calculation unit 32 and the counter 36 each read their of the values Lo, Bo and Co and start calculating Bo-Lo-4å + 4è and Co-4. The input selector 38 compares the difference voltage Vo with the limited voltage VD and emits a voltage VE. The voltage VE deviates depending on o B ^ -Lo $ .0 or 70. 1) 'if: ao-Lo so. When the cut-off signal is output, the signal M from the calculation unit 32 is negative (since Bo-Lo S0 and ÖA and ÖB are equal to zero) and the error signal VC is negative. The differential voltage Vo (= A-VC) is therefore higher than the reference voltage VA. Since the stop voltage VB is set to a higher value than the maximum value of the reference voltage VA at the time when the cut-off signal is emitted, the voltage VD will also be equal to the reference voltage VA. The input selector 38 will therefore select and output the differential voltage V0, so that the motor 21 for the feed rollers will be constantly driven with the differential voltage Vb. av _, z) om: ao-Lo> o _ ”° s.

When the cut-off signal is output, the signal M from the calculation unit 32 is positive, since Bo-Lo> 0 and 49A and ÖB A are still equal to zero. The fault voltage VC is therefore also positive. The differential voltage Vo (= VA-VC) will therefore be lower than the reference voltage VA. Since the limited voltage VD is equal to the reference voltage, the input selector 38 selects the reference voltage. The second motor 21 will thus be driven with the reference voltage VA. The content N (= Co-4) in the counter 36 and thus the stop voltage VB will decrease over time, until the latter becomes less than the reference voltage VA. The voltage VD will thus be equal to the stop voltage VB and not equal to the reference voltage VA. Since the input selector 38 now selects the stop voltage VB, the speed of the second motor 21 will decrease. This results in a reduction of the pulse signal Éæ from the generator PGB and thus of the signal M (= Bo-Lo-Qš + Qš) from the calculation unit. The fault voltage VC will therefore decrease gradually, so that the differential voltage Vo (= VA-VC) will increase. If the differential voltage Vo does not become positive, before the stop voltage VB becomes equal to zero, the other motor 21 will stop when VB becomes zero, but will restart and be driven by the differential voltage Vo from the time when Vo becomes positive. If the differential voltage Vo becomes equal to or greater than the stop voltage VB, before VB becomes equal to zero, the motor 2l will be driven by Vo from the time when Vo has become equal to VB.

The control clutch described above ensures that the feed rollers driven by the second motor 21, when the motor 21: is controlled by the differential voltage Vo, will be controlled in such a way that they rotate synchronously with the cutting unit 2. Then - M and thus VC is equal to zero. The reason will be described in the vase below. i ._ If the cutting unit 2 operates at a higher speed than the feed fa »ew = ß ° ßf * the rollers 6, the pulse signal QÄ will be larger than the pulse vf of the signal Éë, so that the calculation result (H = Bo-Lo-4å + Û%) and 2 å thus the fault voltage VC will be less than zero. The differential voltage Vo will therefore be greater than the reference voltage VA with the fault voltage Vt (Vo = VA - (- | VC |) = VA + | VJ).

As a result, the inheritance of the feed rollers 6 "will increase and the pulse signal $ B will increase, so that the signal M will return to zero. The rollers 6 are therefore immediately returned to synchronization with the cutting unit 2.

If the cutting unit 2 then operates at a lower speed than the rollers 6, the pulse signal (ha will be less than ÖB, so that M and thus VC will be greater than zero. The difference voltage Vo (= VA-VC) from the amplifier 35 will therefore A. As a result, the speed of the rollers 6 will decrease, thereby reducing the pulse signal. $%, So that M (= Bo-Lo-4Ä + @ å) will be kept at zero, so that the rollers 6 are returned to synchronization with the cutting unit. 2. to be less than the reference voltage V When the cutting unit has completed a cutting process, while being kept synchronized with the feed rollers, the sensor 23 emits another cutting end signal and the control coupling will start working for another cutting period.

Pig. 5 shows a further embodiment of the guide coupling, in which the motor 18 for the cutting unit 2 is controlled in relation to the motor 21 for the rollers 6.

The control circuit shown in Fig. 5 differs from that shown in Fig. 4 in that the counter 36 receives the pulse signal Qk and not Qa and performs the calculation Co-QR. that the converter 34 receives the pulse signal @% and does not go, that the speed command unit 39 receives a feedback voltage VF from the tachogenerator 19 and not 22, that the calculation unit 32 receives Ck and .Q% at other terminals and carries it through Lo-Bo - $ g + ¶à expressed calculation and that m0t ° fStYfe fl h @ Ce fl 40 drives the motor 18 and not the motor 21. With this mode of operation, Co is a preset value, which is proportional to the angle over which the crank arms are turned during the period from the end of the cut to its Stop.

The second embodiment of the control clutch operates in the following manner.

Depending on the cut-off signal from the sensor 23, the calculation unit 32 and the counter 36 are supplied with the values Lo, Bo and Co and begin calculation of Lo-Bo- @ š + d% and calculation of Co-ik, respectively. The input selector 38 compares the differential voltage Vo with the limited voltage VD and outputs a voltage VE, which is different depending on whether Lo-Bo << 0 or Lo-Bo šO. l) If Lo-Bo <0 At the time when the cut-off signal is emitted, the signal M is negative (because Lo-Bo is zero) and the error signal VC is also negative. The differential voltage Vo (= VA-VC) will therefore be higher than the reference voltage VA. Since the voltage VD is the reference voltage VA, the motor 18 of the cutting unit will be constantly controlled by means of the differential voltage Vo. 2; if Lo-ao eo 'At the time when the cut-off signal is emitted, the signal M and thus the error signal V are positive. The differential voltage Vo (= VA-VC) will therefore be lower than the reference voltage VA. Since the voltage VD is the reference voltage VA, the input selector 38 selects the reference voltage. The motor 18 for the cutting unit will therefore be driven by means of the reference voltage VA. Meanwhile, the content N (= Co-4%) in the counter 36 and thus the stop voltage VB will decrease, until the latter becomes less than the reference voltage VA. Now the voltage VD will be the stop voltage VB and not VA. As the input selector 38 selects the stop voltage VB, the speed of the motor 18 will decrease. This causes the pulse signal $ Ä from the pulse generator PGA to decrease and thus the signal M (= Lo-Bo-4è + qà) from the calculation unit. The error signal VC will therefore decrease gradually and the difference signal vo (= VA-VC) will consequently increase. If the difference voltage Vo does not become positive, before the stop voltage VB becomes equal down FQWH .. V.,, _. 9 zero, the motor 18 will stop when VB becomes equal to zero, but it will start again and be driven by the differential voltage Vo from the time when Vo has become positive. If the difference voltage Vo becomes equal to or greater than the stop voltage V, before VB becomes equal to zero, the motor 18 will be controlled by means of the difference voltage Vo from the time when Vo becomes equal to VB.

The above-mentioned control coupling ensures that the cutting unit 2 driven by the motor 18, when the motor 18 is controlled by means of the differential voltage Vo, will be controlled in such a way that it operates synchronously with the feed rollers 6. Then M and thus VC is equal to zero. The reason will be described below.

If the rollers 6 rotate at a higher speed than the cutting unit 2, the pulse signal lock will be larger than the pulse signal Ck, so that the calculation result (M = Lo-Bo-4g + Ûà) and thus the error signal V will be less than zero. The difference voltage Vo will therefore exceed the reference voltage VA with the fault voltage VC (Vo = VA - (- | Vc |) = VA + | VC |). As a result, the speed of the cutting unit 2 will increase, so that the pulse signal iß will increase, until the signal M returns to zero. As a result, the cutting unit is immediately returned to synchronism with the feed rollers 6.

If the rollers 6 rotate at a lower speed than the cutting unit 2, the pulse signal Q> B will be smaller than 43A, so that the signal M and thus VC will be larger than zero. The difference voltage Vo (= VA-VC) will therefore be smaller than the reference voltage VA. As a result, the cutting unit speed will decrease. This reduces the pulse signal run, so that M (= Lo-Bo- @ ë + ¶) will be kept at zero. The cutting unit has therefore been brought back into synchronism with the feed rollers 6.

Pig. 6 shows a further embodiment of the control coupling, in which either the motor 18 for the cutting unit or the motor 21 for the feed rollers can be controlled in relation to the second motor. In this case, a switching device is included for selecting the control mode, ie. either the control method applied in Fig. 4 or the control method applied in Fig. S. Inputs to the calculation; . 1.7? in the unit 32, the converter 34, the counter 36 and the speed order unit 39 as well as the motor intended for control can be selected by means of a switch 41. In the pulse signal Öb or QR the calculation unit 32 and the counter 36 are supplied via a switch A1 or B1 on the switch 41. The pulse signal 4> A ene: on: is introduced into the calculation unit 32 and the converter 34 via a contact A2 or 82. The speed command unit 39 is supplied via a contact B3 or A3 with the signal from the roof generator 19 or 22. The signal from the motor control unit 40 is supplied to the motor 18 or 21 via a switch B4 or A4¿ On the switch 41 the contacts A1, A2, A3 and A4 are locked together. In the same way, the contacts B1, 82, B3 and 84 are locked together.

When the contacts A or B on the switch 41 are selected, the third embodiment of the control coupling shown in Fig. 6 will operate in the same way as the first or the second embodiment.

Although the pulse signal $ B in the second embodiment is fed from the pulse generator PCB, the current web speed can be sensed by means of a measuring wheel located between the feed rollers and the cutting unit, so that it rotates under friction with the moving web.

In the above-mentioned control coupling, the values Lo and Bo are determined in such a way that the cutting unit will be brought into synchronism with the web speed no later than before the next cutting begins. x Although the cutting unit 2 in the particularly suitable embodiment is driven directly by the motor 18, it can be driven via speed changing means such as a universal joint or the like to ensure more precise cutting. A sensor of another type for sensing the beginning of the cutting process can also be used. Furthermore, a speed compensator may be provided before or after the transducer 34 for more accurate cutting. As a result of the invention, a cutting machine with higher productivity is obtained, while the advantages of the cutting machine of the flat plate type are maintained, i.e. simple knife mounting and high cutting accuracy.

Claims (4)

10 15 20 25 30 35 v ._ .aggr- '_ = 1 ° 40§xï & ¶ Cutting machine for cutting a continuous web of materials (- for blanks of the desired shape and size, comprising a cutting mechanism with eu: xnivbiaa and a pad in the device and transmission means for operating the blade and the pad in such a relationship that the blade touches the pad at a point traveling from one end of the pad to its opposite end, and feed rollers for feeding the web to the cutting mechanism, characterized by a first motor (18) for operating the cutting mechanism (2), a second motor (21) for operating the feed rollers (6), control elements for controlling either the first (18) or the second (21) motor in relation to the second of the two motors, so that the suitably sufficient length of the web (1) for a cut is fed to the cutting mechanism (2) during an entire operation of the cutting mechanism and this is kept synchronized with the web speed at least during the time period from the beginning to the end of the cutting process. 2. A machine according to claim 1, characterized by a switch (41) for selecting the motor (l8,2l) to be controlled by the control elements. Machine according to claim 1 or 2, characterized in that the control elements comprise a first generator (PGA) for generating pulses (WA), the number of which is proportional to the traversed angle of rotation of the first motor (18), a second generator ( PGB) for generating pulses (08) whose number is proportional to the length of the applied path (1), a converter (34) for converting the pulses (øA or 03) from the first (PGA) or the second (PGB) the pulse generator to a reference voltage (VÄ), a step (31) for setting a first value (LO) which is 10 15 20 25 30 EÜ- * äfqfch; '§§¶àš% @ ¶§E; šát l proportional to the length to which the web (1) is to be cut, and a second value (Bo) which is proportional to the number of revolutions of the first motor (18) during a * V¿ operation of the cutting mechanism (2), a sensor (23) son "w emits a signal each time the mechanism terminates a cutting process, a calculation unit (32) receiving the first (Lo) and the second (Bo) value from the setting step (31) depending on the signal from the sensor (23) and performs a calculation (Bo-Lo-øA + øB or Lo-Bo-øB + QA) to obtain a signal (M) proportional to the calculation result, a difference generator (35) which subtracts the signal from the calculation unit (32) from the reference voltage (VA) from the converter (34) to obtain a signal proportional to the difference between these signals, an input selector (38) for selecting the higher value signal the transformers (34) and the differential generator (35), and a motor control stage (39, 40) for controlling the second (21) and the first (18) motor according to the signal from .. -, _ \., _ ;. __k ~; ¿. e nun-_ »b-» š-wv Gevxs- fi imlß fi- l ', ~. «' - iii-e 2. ' the input selector (38). Machine according to claim 3, characterized in that the setting step (31) sets a third value (Co), which is proportional to the number of revolutions of the second (21) or the first (18) motor during the period from the end of the cutting process until the the second or first motor has stopped, and that a counter (36) is arranged which receives the third value (Co) depending on the signal from the sensor (23) and performs a count (Co-GB or Co-øA) to form a stop voltage (VB) which is reduced by means of the reference voltage (VA). wherein, the input selector (38) selects the signal with a higher value * »~ of the signal from the differential generator (35) and the stop voltage (V) reduced by -_, the reference voltage (V). A B ¿(