JPS6144639B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention relates to sheet materials such as corrugated cardboard sheets (hereinafter simply referred to as sheets) that are continuously fed at high speed.
This invention relates to a control device for a rotary cutter for automatically cutting wood into desired dimensions.

[Conventional technology and problems]

To explain the mechanical aspects of an example of the conventionally used rotary cutter as described above, as shown in FIGS. A reduction gear section 4 is attached. A direct current 5 for driving the rotor 2 is coupled to the reduction gear section 4, and the direct current motor 5 is connected to a tachogenerator 6 for detecting its rotational speed and the rotation angle of the motor 5, that is, the rotation angle of the rotor 2. A pulse generator PG _B is provided for detecting. On the other hand, the sheet X is fed at a substantially constant speed through the pair of rotors 2, and is constantly in contact with one side of the sheet X to be cut with a predetermined pressure.
A wheel 7 is provided which is driven by the travel of the sheet X, and another pulse generator P _A is coupled to the shaft 8 of the wheel 7 in order to detect the amount of rotation thereof, that is, the amount of travel of the sheet X.

Further, a cutting completion sensor 9 such as a proximity switch is provided which detects when the blade 1 of the rotor 2 moves a predetermined distance ₁ in the rotational direction from the cutting point P of the sheet X by the blade 1 of the rotor 2 and generates a cutting completion signal C. ing.

With such a rotary cutter, the sheet X is accurately cut into a predetermined length. In other words, in order to cut to a fixed length, the cutting length is determined every time the blade 1 of the rotor 2 passes a predetermined position after cutting is completed, that is, every time the cutting completion sensor 9 generates the cutting completion signal C.
_The number of pulses corresponding to the difference L = L ₀ - B ₀ between L ₀ and the circumferential length B ₀ of the rotor 2 is read into the register, and the number of pulses φ _A (i.e. (represents the travel distance of seat X)
As the rotor 2 rotates, the pulse generator PG _B
While subtracting the difference φ _A −φ _B between the generated pulse φ _B (i.e., representing the amount of rotation of rotor 2) from the above L (i.e., subtracting R = L ₀ − B ₀ − (φ _A − φ _B ) ), the voltage corresponding to the difference R is V _c =f(R)
and the voltage obtained by frequency-voltage (F/V) conversion of the output of the pulse generator PG _A , that is, the voltage V _A representing the traveling speed of the sheet X, the difference V ₀
A fixed length cutting control device is used which gives =V _A -V _c as a speed command to the control circuit of the motor 5 only when V ₀ >0. Note that when V _A ≦V _c , that is, when V ₀ ≦0, V ₀ =0 is given as the speed command, and the motor 5 is stopped.

In the fixed length cutting control device as described above, the difference between the cutting length calculated in terms of the number of pulses and the circumference of the rotor 2 with respect to the speed voltage V _A of the sheet X is L = L ₀ -
The speed of the motor 5 is determined by adding or subtracting the voltage V _c corresponding to the value obtained by subtracting the difference between the actual travel distance φ _A of the seat X and the actual rotation amount φ _B of the rotor 2 from B ₀ .
In other words, the rotational speed of rotor 2 is the cutting length L ₀ and the circumference
The speed of the sheet _X is compensated for according to the difference between B ₀ and the difference between the actual traveling distance φ _A of the sheet Subtracting the difference _{φ A - φ B between} the traveling distance of _the sheet In other words, the speed of rotor 2 is synchronized with the speed of sheet X by setting V ₀ =V _A , and during this period φ
_{Sheet _} Can be cut to length.

However, in the fixed length cutting control device as described above, the cutting length L ₀ is longer than the circumferential length B ₀ and the moment when L=L ₀ −B ₀ is read after cutting is completed, V ₀ =V _A −
When V _c <0, the control circuit of the motor 5 has V ₀
= 0 is given as the speed command, and the motor 5 suddenly stops, resulting in an excessive load on the motor.
There is a problem in that the blade 1 of the rotor 2 interferes with the cut sheet or the supplied sheet and causes overlap.

To solve this problem, the speed command given to the motor control circuit after cutting is not V ₀ = 0, but the motor 5 is set at a position where the rotor 2 has rotated by a sufficient angle so that the load on the motor 5 is not excessive. It is conceivable to make it stop. In other words, after completion of cutting, the speed command V ₀ given to the motor control circuit is set to the reference voltage V _R indicating the stop position of the rotor.
, the signal indicating the actual position of the rotor 2 or motor 5 is fed back from the state of V ₀ =V _R , and the voltage corresponding to that signal is the reference voltage V _R
Position control using a servo loop that stops the motor 5 at a point equal to
It is disclosed in the specification of No.

However, the stop control in the above U.S. patent is such that the shear is always stopped at a predetermined position every time switching is completed, and the shear is continuously fed at high speed, like the rotary cutter targeted by the control device of the present invention. It is difficult to easily apply this method to control in which a combination of acceleration, deceleration, and stopping of the rotor must be automatically selected and performed due to the relationship between the cut length of the sheet and the circumferential length.

This invention was made in view of the above circumstances,
The purpose of this is to control the rotor to rotate a predetermined angle after cutting, then stop, and then accelerate again, decelerate and then accelerate again, or accelerate and then decelerate, based on the relationship between cutting length and circumference. To provide a control device for a rotary cutter which can automatically select and perform operations and can smoothly stop or decelerate a rotor without placing an excessive burden on a motor.

[Means for solving problems]

This invention was made to solve the above problems, and each time the rotor blade of the rotary cutter passes a predetermined position after cutting is completed, the cutting length L ₀ of the sheet and the circumference B of the rotor are set in advance. Difference L from ₀
= L ₀ - B ₀ Read the number of pulses corresponding to this L
R= _{L 0 −B 0 −} (φ _A −φ
_B ), converting this R into a voltage to obtain a compensation voltage V _c =f(R), compensating the speed voltage V _A representing the traveling speed of the seat with the compensation voltage V _c ,
In a rotary cutter control device equipped with a fixed length cutting control circuit that generates a first speed command voltage V ₀ =V _A −V _c of a control circuit of a motor that drives a rotor; the polarity of the first speed command voltage V ₀ and determine that V ₀ ≦0
a polarity discrimination comparator which generates a signal _{S N} indicating that when a stop control circuit having a reversible counter for subtracting the number of pulses φ _B representing the amount of rotation of the rotor from the reversible counter, and a D/A converter for converting the content of the reversible counter into a direct current voltage V _B proportional to the content of the reversible counter; ;The above polarity discrimination comparator detects the above signal S _N
The present invention is characterized by comprising a switching circuit that applies V ₀ to the motor control circuit when the comparator does not generate the signal _SN , and V _B to the motor control circuit as the final speed command voltage _VR when the comparator generates the signal SN.

In this application, the symbol L ₀ represents the cutting length and the number of pulses corresponding to the cutting length, and B ₀ represents the circumferential length and the number of pulses corresponding to the circumferential length. Furthermore, the term "after the cutting is completed" includes the moment when the cutting is completed.

〔Example〕

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a control device for a rotary cutter according to the present invention will be described below with reference mainly to FIG.

The control device of the illustrated embodiment includes a cutting completion sensor 9 that generates a cutting completion signal C every time the blade 1 of the rotor 2 of the rotary cutter (see FIGS. 2 and 3) passes.
(provided at an appropriate position in the rotation direction from the position where the blade 1 completely finishes cutting the sheet X), the above signal C
A timing signal generator 10 generates a timing signal α ₁ every time the desired cutting dimension L ₀ is input.
cutting dimension setting section 11 in which the circumferential length _B0 of the rotor 2 is set _digitally by a keyboard or the like; The first step calculates the difference L=L ₀ −B ₀ from L ₀ and B ₀ input as the number of pulses from the setting unit 12.
Operation unit 13, output of pulse generator PG _A φ _1A
The seat traveling distance detection circuit 14 performs necessary coefficient processing to generate the pulse number α _A representing the traveling distance _of the seat A rotor rotation amount detection circuit 15 that generates the number of pulses φ _B representing the amount of rotation, and a seat travel distance detection circuit that detects the travel distance of the seat X with respect to L=L ₀ −B ₀ inputted from the first calculation section 13. Rotor rotation amount detection circuit 1 according to the rotation of φ _A and rotor 2 supplied from 14
From the second calculation unit 16, which subtracts the difference φ _A −φ _B from φ _B supplied from 5, that is, R = L ₀ − B ₀ −(φ _A −φ _B ), A digital-to-analog (D/A) converter 17 converts the contents output every moment, that is, the number of pulses R, into a DC voltage proportional to this, and the output voltage of this D/A converter 17 is processed by a predetermined function. Compensation voltage V _c representing the above pulse number R = L ₀ −B ₀ −(φ _A −φ _B )
A function generator 18 that outputs = f [(L ₀ - B ₀ ) - φ _A - φ _B )] converts the output φ _1A of the pulse generator PG _A into a voltage proportional to its frequency and causes the sheet X to travel. Voltage proportional to speed, i.e. speed voltage V _A
A frequency-voltage (F/V) converter 19 that generates the voltage and a calculation that calculates the difference between the speed voltage V _A and the compensation voltage V _c and outputs the first speed command voltage V ₀ =V _A −V _c Standard length cutting control circuit 30 consisting of amplifier 20
has.

Furthermore, a polarity determination comparator 40 that determines the polarity of the first speed command voltage V ₀ , a stopping distance setting unit 51 that digitally sets a distance φ _S at which the blade 1 of the rotor 2 is stopped after cutting is completed, and the polarity determination comparator 40 that determines the polarity of the first speed command voltage V 0 The moment 40 generates the signal S _N indicating that V ₀ ≦ 0, read the above φ _S as the number of pulses, and then read the number of pulses φ _B supplied from the rotor rotation amount detection circuit 15 as the rotor 2 rotates. a reversible counter 52 that subtracts and outputs φ _S −φ _B ;
A D/A converter 53 converts the content φ _S −φ _B of the reversible counter 52 into a DC voltage proportional to this, and the output voltage of the D/A converter 53 is processed by a predetermined function to produce an output voltage V _B a stop control circuit 50 comprising a function generator 54 that generates =f(φ _S −φ _B );
Motor control for controlling the motor 5 by using V ₀ as the final speed command voltage _VR when the polarity discrimination comparator 40 does not generate the signal _SN , and V _B as the final speed command voltage _VR when the comparator 40 generates the signal SN A switching circuit 60 is provided which supplies the circuit 70. Note that since the generation of the signal S _N is based on the cutting completion signal C and the timing signal _α1 , the reading of the number of pulses φ _S to the reversible counter 52 and the start of subtraction of the number of pulses φ _B are performed, for example, by generation of the timing signal. It may also be arranged to be performed in synchronization with the signal generation from the device 10.

The operation of the control device of this embodiment having the above configuration will first be explained when the cutting length L ₀ is longer than the circumferential length B ₀ (third
In the figure, the case where L ₀ = L ₀₂ ), that is, L ₀ > B ₀ , will be explained with reference to the graph in Figure 4.
At the moment when the blade 1 of the rotor 2 passes the cutting completion sensor 9 at time t ₀₁ , the timing signal α ₁ is supplied to the first calculation unit 13 from the timing signal generator 10 which receives the cutting completion signal C from the sensor 9 as input. , _the first calculation unit 13 reads the cutting dimension L ₀ of the _sheet −B ₀ is calculated instantaneously.
This L=L ₀ -B ₀ is set in the second calculation section 16.

On the other hand, the number of pulses φ _A representing the seat travel distance output from the seat travel distance detection circuit 14 by inputting the output pulses of the pulse generator PG _A as the seat X travels, and the pulses as the rotor 2 rotates. The number of pulses φ _B representing the amount of rotor rotation outputted from the rotor rotation amount detection circuit 15 by inputting the output pulses of the generator PG _B is also calculated by the second calculation unit 16 .
The second arithmetic unit 16 receives the input from the first arithmetic unit 13 and subtracts φ _A every moment from the set L=L ₀ −B ₀ and adds φ _B every moment. That is, the calculation L-(φ _A −φ _B ) is performed. The D/A converter 17 converts the content R of the second calculation section 16, which is calculated and changed every moment, into an analog voltage,
Input to function generator 18. The function generator 18 processes the output of the D/A converter 17 using a predetermined function determined mainly by design parameters to generate a compensation voltage V.
_c = f(R) = f [(L ₀ −B ₀ )−(φ _A −φ _B )] is output. It should _be noted that for some reason _the seat
increases R by the amount by which the seat X is retracted, and φ _B acts to decrease R by the amount by which the rotor 2 reverses.

This compensation voltage V _c is input to the operational amplifier 20 together with the speed voltage V _A of the sheet X obtained by passing the output φ _1A of the pulse generator PG _A through the F/V converter 19, and the first speed command voltage V ₀ = V _A −V _c is calculated.

Note that the term compensation voltage here refers to the speed command voltage that determines the speed of the drive motor 5 of the rotor 2 with respect to the substantially constant speed voltage V _A of the sheet X traveling at a substantially constant speed, and the cutting length L ₀ . It is used in the sense of compensating for the difference between the circumferential length B ₀ and the difference between the actual travel amount φ _A of the seat X and the actual rotation amount φ _B of the rotor 2 . In other words, if L ₀ = B ₀ , the motor 5 should be driven with a speed command (V ₀ =V _A ) equal to the speed voltage V _A of the seat X, so that φ _B follows φ _A. However, if L ₀ > B ₀ , the speed of motor 5 should be made slower than _{the speed} of sheet Motor speed needs to be increased.

Therefore, in the control device of the present invention, regardless of the driving speed of the rotor 2 between successive cutting operations, the sheet X travels L ₀ (i.e., φ _A = L ₀ ), the blade 1 of the rotor 2 is controlled to rotate by B ₀ (that is, φ _B =B ₀ ) (including the case where the rotor 2 is stopped midway. Also, the above equation for V _c The middle term (φ _A −φ _B ) also has the meaning of compensating for the speed difference between the two during the cutting period, that is, while the rotor 2 is driven at the same speed as the sheet X.

Then, at time t ₀₁ , L = L ₀ - B ₀ is the second
If L is large enough to satisfy V _A ≦V _c at the moment it is read into the arithmetic unit 16 , a signal S _N indicating that V ₀ = V _A −V _c ≦0 is sent from the polarity discrimination comparator 40 to the stop control circuit 50 . It is supplied to counter 52 and switching circuit 60. This moment reversible counter 52
reads the stopping distance φ _S of the blade 1 of the rotor 2 after cutting is completed, which is set in the stopping distance setting section 51 in advance. The reversible counter 52 subtracts the number of pulses φ _B supplied every moment from the rotor rotation amount detection circuit 15 from this φ _S . The content φ _S −φ _B of the reversible counter 52 is converted into an analog voltage by the D/A converter 53, and then processed by a predetermined function by the function generator 54, so that V _B =f(φ _S −φ _B ) to the switching circuit 60. The switching circuit 60 is
Since the signal S _N is supplied from the polarity discrimination comparator 40, the final speed command voltage V _R of the motor control circuit 70 is changed from the output V ₀ of the operational amplifier 20 to the output V _B of the stop control circuit 50 = f (φ _S − φ _B ), and the device enters the stop control mode (stop period; see Figure 4).

During this stop period, the motor 5 is V _R =V _B =f(φ
_S - φ _B ), but at the moment t ₀₁ when L = L ₀ - B ₀ is read into the second calculation unit 16, V _B
is set so that V _A ≦V _B with respect to the speed voltage V _A of the sheet X (φ _S is set large). In this way, at the cutting completion time _t01 , the blade 1 of the rotor 2 prevents the sheet X from moving forward,
In order to prevent the sheet
It is desirable that _A ≦V _S =f(φ _S ).

Thereafter, as φ _B advances due to the rotation of the rotor 2, the motor 5 is decelerated as V _B decreases, and φ _B =
At time t ₁ when φ _S occurs, V _R =V _B =0 and it stops, and is maintained at that position until the next time t ₂ .
In this way, depending on the value of L = L ₀ - B ₀ , the motor 5
Even when it is necessary to stop the motor 5, the motor 5 is first accelerated at V _R = V _B = f (φ _S ) and then slowly decelerated at φ _B = φ _S until V _R =0. Therefore, the load on the motor 5 does not become excessive.
Further, the advance of the sheet X is not hindered by the blades 1 of the rotor 2.

During this stop period (t ₁ to t ₂ ), the rotor rotation amount φ _B
does not increase, f[(L ₀ −B ₀ )−(φ _A −φ
_B )] decreases rapidly as φ _A advances, and at time t ₂ V _A
= V _c , and after this, V _A > V _c , that is, V ₀ > 0, and the signal S _N of the polarity discrimination comparator 40 is no longer output, so the final speed command V _R is V _R = V ₀ and the motor 5 is activated and accelerates as V ₀ increases. As φ _B begins to advance when the rotor 2 is started, the increase in V ₀ is somewhat slower than during the stop period, but at first the advance of φ _B is slower than φ _A , so V ₀ (=V _R ) increases, the motor 5 is accelerated, and when it reaches _t3 , L0 _{- φA} = _B0 - _φB , _Vc =0, and cutting is started. At _this time point _{t3 ,} L0 _{- φA represents} the distance that the sheet The design is such that the blade 1 bites into the sheet X at the time _t3 when the two become equal.

During the cutting period, that is, from the start of cutting t ₃ to the completion of the next cutting t ₀₂ , the relationship L ₀ −φ _A =B ₀ −φ _B , that is, V _c =0, is maintained (with the progress of φ _A) . _φB
), the motor 5 has V _R =V ₀ =V
_A , that is, the seat X is driven synchronously with a speed command voltage equal to the traveling voltage of the seat X. During this period, rotor 2
When the speed of sheet _{X deviates} from the _speed of sheet Control is then performed to cause the rotor speed to follow the sheet speed. Then, when φ _A = L ₀ and φ _B = B ₀ reach time t ₀₂ , cutting is completed, and as in the previous t ₀₁ ,
A cutting completion signal C is output from the cutting completion sensor 9, and the above operation is repeated thereafter. In addition, FIG. 4 shows the final speed command voltage V in the above control operation.
Changes in _R are shown by thick lines.

Next, even if L ₀ > B ₀ , when L=L ₀ −B ₀ is read into the second calculation unit 16, V _A ≦V _c , that is, V ₀ ≦
If it is not so large as to become 0, the signal S _N is not output from the polarity discrimination comparator 40, and the motor 5 is driven by V _R =V ₀ =V _A −V _c (<V _A ). That is, the motor 5 temporarily begins to decelerate as V ₀ decreases, but without stopping, it is accelerated again as V _c decreases due to the advance of φ _A , and V _c =0, that is, V ₀ = When V _A is reached, cutting is started in the same manner as above. In this case, the stop control circuit 50 is not involved in controlling the motor 5, and the motor 5 is controlled exclusively by the regular length cutting control circuit 30.

Furthermore, if the cutting length L ₀ is shorter than the circumferential length B ₀ of the rotor 2 (L ₀ =L ₀₁ in Fig. 3), L =
Since L ₀ −B ₀ <0, L becomes the second
At the moment when it is read into the calculation unit 16, V _c becomes <0, and V _R
=V ₀ =V _A -V _c >V _A , the motor 7 is accelerated by 〓V _{c 〓} to become faster than the speed of the sheet and during cutting, again V _R =V ₀ =V _A (V _c =
0), and the rotor 2 is driven at the same speed as the sheet X. In this way, when L<0, the output V ₁ of the stop control circuit 40 is not involved in the control of the motor 7, and the motor 7 is exclusively controlled by the regular length cutting control circuit 3.
Controlled by 0.

〔Effect of the invention〕

As explained in detail above, according to the rotary cutter control device of the present invention, the combination of acceleration, deceleration, and stopping of the rotor is controlled based on the relationship between the cutting length and the circumference of sheets that are continuously fed at high speed. Not only can it be selected automatically and instantaneously, but it also allows the rotor to rotate sufficiently, especially when the cutting length of the sheet is longer than the circumference of the rotor and the rotor must be stopped once the cutting is complete. Since the motor is stopped from
Furthermore, the sheet does not become loose due to interference between the rotor blade and the sheet due to a sudden stop or deceleration of the rotor.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of an embodiment of a control device for a rotary cutter according to the present invention, Fig. 2 is a perspective view showing the mechanical structure of an example of a rotary cutter, and Fig. 3 shows the rotational phase of the rotor during control operation. An explanatory diagram showing an example and the relationship between the circumferential length and the cutting length, FIG. 4 is a graph showing the pulse count of each part and the change in voltage according to the pulse count when the cutting length is longer than the circumferential length. 1...blade, 2...rotor, 5...motor, 9...
... Cutting completion sensor, 10 ... Timing signal generator, 11 ... Cutting dimension setting section, 13 ... First calculation section, 12 ... Perimeter setting section, 14 ... Sheet travel distance detection circuit, 15 ... Rotor Rotation amount detection circuit, 1
6... Second calculation unit, 17... D/A converter, 19
...F/V converter, 20...Operation amplifier, 40...
... Polarity discrimination comparator, 50 ... Stop control circuit, 51 ... Stop distance setting section, 52 ... Reversible counter, 53 ... D/A converter, 60 ... Switching circuit, 70 ... Motor control circuit, PG _A , PG _B ...Pulse generator.

Claims (1)

[Claims] 1 Every time the rotor blade of the rotary cutter passes a predetermined position after cutting is completed, the difference L between the preset sheet cutting length L ₀ and the rotor circumference B ₀ =
Read the number of pulses corresponding to L ₀ - B ₀ , and from this L, the number of pulses φ A representing the amount of travel of the sheet as it travels, and the number of pulses φ _B representing the amount of rotation as the _rotor rotates, R = L ₀ −B ₀ −(φ _A −φ _B )
is calculated, this R is converted to a voltage, and the compensation voltage V _c
= f(R), and compensate the speed voltage V _A representing the running speed of the seat with the compensation voltage V _c to obtain the first speed command voltage V ₀ = V _A −V of the control circuit of the motor that drives the rotor. In a rotary cutter control device equipped with a fixed-length cutting control circuit that generates _c : Determine the polarity of the first speed command voltage V ₀ and set V ₀
A polarity discrimination comparator that generates a signal S _N indicating this when ≦0; Based on the passage of the rotor at the predetermined position, reads the number of pulses φ _S corresponding to a preset stopping distance of the rotor blade. In addition, a reversible counter for subtracting the above-mentioned pulse number φ _B representing the amount of rotation of the rotor, and D/ for converting the contents of this reversible counter into a direct current voltage V _B proportional to this.
A stop control circuit having a converter; V ₀ when the polarity discrimination comparator does not generate the signal _SN , and V _B when the comparator generates the signal _SN , the final speed command voltage V _R
a switching circuit that supplies the motor control circuit as;
A rotary cutter control device characterized by comprising: