GB1602480A - Method for controlling a cross-cutter and digital regulating system for performing the method - Google Patents
Method for controlling a cross-cutter and digital regulating system for performing the method Download PDFInfo
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- GB1602480A GB1602480A GB2577578A GB2577578A GB1602480A GB 1602480 A GB1602480 A GB 1602480A GB 2577578 A GB2577578 A GB 2577578A GB 2577578 A GB2577578 A GB 2577578A GB 1602480 A GB1602480 A GB 1602480A
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- 230000001105 regulatory effect Effects 0.000 title claims description 110
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- 230000001276 controlling effect Effects 0.000 title claims description 14
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- 238000013178 mathematical model Methods 0.000 claims description 14
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- 238000012544 monitoring process Methods 0.000 claims description 6
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Classifications
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B26—HAND CUTTING TOOLS; CUTTING; SEVERING
- B26D—CUTTING; DETAILS COMMON TO MACHINES FOR PERFORATING, PUNCHING, CUTTING-OUT, STAMPING-OUT OR SEVERING
- B26D5/00—Arrangements for operating and controlling machines or devices for cutting, cutting-out, stamping-out, punching, perforating, or severing by means other than cutting
- B26D5/20—Arrangements for operating and controlling machines or devices for cutting, cutting-out, stamping-out, punching, perforating, or severing by means other than cutting with interrelated action between the cutting member and work feed
- B26D5/30—Arrangements for operating and controlling machines or devices for cutting, cutting-out, stamping-out, punching, perforating, or severing by means other than cutting with interrelated action between the cutting member and work feed having the cutting member controlled by scanning a record carrier
- B26D5/32—Arrangements for operating and controlling machines or devices for cutting, cutting-out, stamping-out, punching, perforating, or severing by means other than cutting with interrelated action between the cutting member and work feed having the cutting member controlled by scanning a record carrier with the record carrier formed by the work itself
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- Life Sciences & Earth Sciences (AREA)
- Forests & Forestry (AREA)
- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Paper (AREA)
- Controlling Rewinding, Feeding, Winding, Or Abnormalities Of Webs (AREA)
Description
(54) METHOD FOR CONTROLLING A CROSS-CUTTER AND DIGITAL
REGULATING SYSTEM FOR PERFORMING THE METHOD
(71) We, JAGENBERG-WERKE AG, of Postfach 1123, 4000 Düsseldorf 1 Germany, a German company, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:
The invention relates to a method of controlling the drive motor of two knife drums which are coupled to each other and are associated with a cross-cutter for material webs, with a digital regulating system arranged to generate a control function in dependence on measured values of process quantities. and to a digital regulating system for performing this method.
A differential transmission with an adjustable differential ratio is usually provided between the drive motor and the two knife drums, which are coupled to each other, in known cross-cutters for material webs. The said differential transmission ensures that the knife drums can be accelerated and decelerated in the course of one rotation for the purpose of adjusting the sheet length and to ensure synchronism between knife drums and material web. The differential transmission must have very large dimensions and represents a substantial cost factor in the manufacture of a cross-cutter.
A method of the kind described hereinbefore is disclosed in a paper by Klaus Bender, entitled "Synthesis of analog computers for the optimum regulation of end values", published in Karlsruhe in 1973. In this method the drive motor operates directly on the two knife drums and is controlled by means of a digital regulating system.
The regulating problem in the present control system is an end value problem.. A system must therefore be capable of being changed into a fresh state not only in the best possible way but it must also be possible for this condition to be precisely set at a given and defined time. It is a particularly critical feature that the end condition is not an inoperative condition.
The knife drum and material web represent two moving bodies which are to meet at a precisely defined time. The knife drum must be moved precisely so that the shear blades coincide with the intended cutting place in the material web in order to obtain the specified sheet length and must therefore also accurately assume the actual velocity of the material web in order to achieve a good cutting quality. The cutting location is defined by the specific design of the machine and for this reason the end time or cutting time is unequivocally defined by the movement of the material web. The fact that both position and speed of the knife drum must be controlled means that at least two variation quantities must be variable in the control function generated by the regulating system so that the two end conditions can be set up.
A linear acceleration characteristic and therefore a paraboloid velocity characteristic is uniformly provided over the entire transition interval for the knife drum in the initially-described method. The two variation quantities a() and a of the control function u = a" + a1 t can themselves be influenced up to the cutting time; a genuine closed-loop control circuit is therefore involved.
Every procedure making use of a digital regulating system or of a digital computer gives rise to a scanning problem because of the sequential mode in which the individual computing steps are performed. Measured values can be transferred from the process to the computer only at discrete times, namely the scanning times, to be processed in the succeeding scanning interval an to be transferred to the process at the next scanning time before new measured values are taken up. As a rule the scanning intervals are selected with constant timing, i.e. they are derived from an independed oscillator or clock, namely as briefly as necessary and possible but at least equal to the necessary computing time for each solution step.
If such on-line solving of the synthesis equations of the regulating system cannot be performed owing to the complexity of the system, the synthesis equations can also be solved off-line and the off-line solution can be transferred to the function generator of the regulating system. These function generators call for a very large memory capacity if the regulation is to have a high degree of accuracy.
According to one aspect of the invention, there is provided a method of controlling the drive motor of two knife drums which are coupled to each other and are associated with a cross-cutter for material webs, with a purely digital regulating system arranged to generate a control function in dependence on measured values of process variables, such as position and velocity of the material web, the scanning points for the measured values of the process variables, such as position and velocity of the material web and position and velocity of the knife drums being defined by positions of the material web and the control function being generated by means of function generators and multipliers.
In a preferred method, very accurate control of the driving motor for the cross-cutter is made possible with the least possible expenditure in terms of memory space in the digital regulating system. the scanning points are defined by marks on the material web.
Advantageously
The scanning points are not specified by a clock, independently of position and velocity, but are derived from the position of the material web. A new scanning point occurs whenever a specific defined distance is traversed. Equidistant location points are provided in place of equidistant times. The scanning points coincide with pre-defined location points on the material web. Accordingly, it is not possible for the scanning points to have intermediate values. Each scanning point is associated with a solution, which can be computed with any degree of accuracy by off-line means and can be stored in a register of relatively small capacity so that the computing time is reduced.
Given a preselected accuracy a preferred method permits shorter scanning intervals thus leading to improved dynamics, a higher material web velocity and therefore a higher output. Alternatively, a higher degree of accuracy can be obtained with a given maximum output.
Quantifying errors are also eliminated since there are no intermediate values.
Advantageously, only the positions of knife drum and material web are detected as process variables by counting of distance increments. This eliminates the problematical detection of the substantially variable drum velocity.
In a particularly advantageous further embodiment of the method according to the invention, the entire interval between consecutive cuts of the regulating system is subdivided into individual phases the length of which takes the form of a geometrical series (1Xbm) and standardization of the measured values is altered in proportion to the phase length in each phase. A further and substantial reduction of memory capacity can thus be achieved. It is convenient to select b = 2 as the basis for the geometrical series.An increase of accuracy in calculating the control function can be achieved with this further embodiment of the method according to the invention because the function values of the function generators provided in the regulating system have very large values close to the cutting point but exhibit a substantially narrower dynamic range reduced phase length.
Furthermore, in generating the control function a mathematical model of distance may be simulated in the regulating system by the use of partial products and this model can be used for the precise control of the knife drum drive. This results in a substantial reduction of sensitivity of the regulating system to disturbances close to the cutting point. The use of partial products in generating the control function makes the simulation of the mathematical model of the distance much simpler than in such a model of conventional construction.
Conveniently, position regulation of the knife drum is performed in the digital regulating system. In this case only a conventional speed and current regulated drive is required.
The set points for the advance motion of the material web can also be specified in the digital regulating system. To this end the optimum set point can be computed by the digital regulating system in dependence on the sheet length.
Finally, run-up to speed of the cross-cutter can be controlled by the digital regulating system and additional superordinate functions can be performed by the digital regulating system. Such functions include, for example, monitoring of cutting errors and correction by adaptation, sheet counting, format control, where appropriate from cut to cut or independently of the desired cutting quantity without interruption. as well as signalling and/or documenting of operating states.
According to another aspect of the invention, there is provided a digital regulating system for performing the method according to the invention, in which two knife drums are coupled to a controlled drive motor and arranged as a cross-cutter fo material webs, and three function generators are provided at the input of the system and contain solution functions F in the form of tables for solutions Di, the three generators function being connected to be driven by a counter which is arranged to be stepped in accordance with the position of the material web, the function generators being connected to multipliers for multiplying the output variables of the function generators by the measured values of the process variables and for generating the control function.The solutions Di correspond precisely to the scanning points, defined by the positions of the material web and their number is therefore limited. These solutions can be precisely off-line computed and are used without intermediate values for generating the control function.
Conveniently, only the solutions Di for one phase of the interval between consecutive cuts, which is subdivided into phases with lengths corresponding to a geometrical series (1/bren), is stored in each of the function generators. By these means it is possible to achieve an exceptionally high saving of register space.
Conveniently, an additional counter connected to the measured value of the material web position and two counters connected to the measured value of the knife drum position are also provided at the input. The velocities of the knife drum and of the material web can be derived by counting the distance increments of the knife drum and of the material web.
A preferred digital regulating system is based on the assumption that the knife drum drive has a double integral characteristic. Actual drives have such ideal characteristics only in rough approximation and end value regulating circuits of the kind described herein have a high degree of sensitivity to disturbances, particularly close to the cutting point. The sensitivity to disturbances can be substantially reduced if the digital regulating system contains a mathematical model of the distance in addition to the end value regulator.
Furthermore, it can advantageously contain a position regulator.
Conveniently, the digital regulating system contains a unit for computing the speed set point value for driving the material web and the digital regulating system can also contain a unit for controlling run-up of the cross-cutter.
The preferred digital regulating unit can perform cutting fault monitoring functions and correction by adaptation as well as similar functions by containing units for performing such additional superordinate functions.
The invention will be further described, by way of example, with reference to the accompanying drawings, in which:
Figure 1 is a diagrammatic view of the knife drum and material web to explain the system of coordinates for the measured process quantities;
Figure 2 is the block circuit diagram of a regulating system for controlling a cross-cutter;
Figure 3 is a graphic view comparing the conditions with equidistant times and equidistant locations as scanning points;
Figure 4 is a block circuit diagram of a regulating system according to Figure 2 with solution registers in place of constant solution functions in the function generators and with a counter for forming the number N,
Figure 5 is a block circuit diagram of a regulating system which is modified with respect to that shown in Figure 4 and in which only the distance increments of the knife drum and material web are counted;;
Figure 6 is a graphic view to explain the subdivision of the transition intervals of the regulating system into individual phases;
Figure 7 is a graphic view to explain the relationship between the individual phases according to Figure 6 for a geometrical series based on b = 2;
Figure 8 is a graphic view relating to the construction of the function generator with and without subdivision into phases;
Figure 9 is a block circuit diagram of the regulating circuit for the cross-cutter with a methematical model of the distance integrated into the digital regulating system;
Figure 10 is a block circuit diagram omf the regulating circuit according to Figure 9 with a position regulator additionally integrated into the digital regulating system; and
Figure 11 is a block circuit diagram of the regulating circuit according to Figure 10, in which the digital regulating system additionally performs superordinate functions.
A meterial web 1 and a knife drum 2 of a cross-cutter are shown diagrammatically in
Figure 1. It will be understood that a further knife drum, coupled to the top knife drum 2, will be situated beneath the material web 1 in the embodiment of the cross-cutter.
The material web 1 moves at a web velocity vl in the direction of the arrow I and the knife drum 2 moves at a knife velocity v2 in the direction of the arrow II. The last cut of the material web has taken place at Sa and the next cut is specified at Sb. The distance between S and Sb defines the sheet length x". The position of the material web 1 is defined by the residual web travel or by the web position xi, and the position of the knife drum 2 is defined by the residual knife travel or by the knife position X2. The shearing circle circumference of the knife drum 2 is X20 = 2 # R.
A paraboloid velocity characteristic of the knife drum is provided uniformly over the entire interval between consecutive cuts for the preferred method and for the associated digital regulating system. Dependent on measured values of the process variables the digital regulating system generates a control function. The two variation values ao and a1 of the control function u = aO + a1 t, where t is time, themselves can be influenced up to the cutting time and for this reason the system represents a genuine closed control loop.
For the construction of the digital regulating system it is assumed that the knife drum drive has a double integral characteristic. The following system of equations is therefore obtained for the standardized and time-transposed synthesis equations of the digital regulating system in which the variables are throughout dimensionless; α0 + α1 . # + α2 . #2 + α3 . #3 = V*1 . x2* (t)
al + 2a2 X + 3a3 x2T2 = 1/2 v2 (t) α0 + α1 + α2 + α3 = 0
a1 + 2a2 + 3a3 = 1/2 k vt T = 1 - 2 xl (t)
The associated control function is defined as::
u* (t) = v*1 . (2α2 + 6 . α3 . #) when u (t) = 4 . b2 . u* (t) . m/sec a
The term * in the process quantities means that these process quantities occur in the system of equations in standardized form, i.e. dimensionless form, between +1 and -1. # represents the standardized time t. The other quantities including a and b are also dimensionless constants. Further details of the above-mentioned system of equations and of the control function are disclosed in the previously-mentioned paper by Klaus Bender, entitled "Synthesis of analog computers for the optimum regulation of end values", published in Karlsruhe in 1973.
Figure 2 shows the block circuit diagram of a regulating system for a cross-cutter drive which is constructed in accordance with the above-mentioned system of equations together with the equation for the control function. The measured values of the standardized web positions x1* are supplied at the scanning points to three function generators 3, 4 and 5. The solution functions F (xl), i.e. the solution functions F1 (x1), F2 (x1) and F3 (xl) of the function generators 3, 4 and 5 are computed by off-line means.The output quantity of the function generator 3, i.e. the function F1 (xt) is supplied to a multiplier 6 and is multiplied therein by the measured value of the standardized knife position x 5. The output quantity of the function generator 5, i.e. the function F3 (xl) is supplied to a proportional element 7.
The factor k of the proportional element 7 defines the ratio v 2/viD at the end time. The output quantities of the multiplier 6 and of the proportional element 7 are summated and
transferred to a further multiplier 8. The sum of the output quantities of the multiplier 6 and
of the proportional element 7 is multiplied by the measured value of the standardized web velocity vl in the aforementioned multiplier 8.
The output quantity of the function generator 4, i.e. the function F2 (x1) is multiplied in a multiplier 9 by the measured value of the standardized knife velocity v*. The output quantities of the multipliers 8 and 9 are summated and supplied to a further multiplier 10 in which the sum of the said output quantities is multiplied by the measured value of the standardized web velocity vl. The desired standardized control function u appears at the output of the multiplier 10.
Initially the functions F1 (xl), F2 (xl) and F3 (xt) are constant functions and could be solved by means of analog function generators. However, the accuracy of an analog solution would be insufficient for the accuracy required for controlling the knife drum. The function generators 3, 4 and 5 are therefore digitally embodies so that the function values Fi are entered in tabulator form into a memory but owing to the accuracy requirements this calls for digitalization into very fine steps. Nevertheless, the values of Fi and xiK as well as the products x9. F1 and v*2. F2 are basically subject to quantifying errors if equidistant times are selected as scanning points.The table or register must become very large in dependence on the required accuracy. The quantifying error is substantially eliminated if the scanning points for the measured values of the process quantities are defined in dependence on the web position x1 or of the standardized web position x*1.
Figure 3 is a graphic view comparing two regulating systems which operate with equidistant times (Figure 3a) and equidistant location points (Figure 3b) as scanning points.
Figure 3a illustrates scanning at equidistant times To~1, Tm, Tm+1. In this x*1, k is always the kth value of the web position * as obtained by digital measurement. Fi.k iS the solution function of the function generators 3, 4 or 5 when i = 1, 2 and 3 and k is equal to the kth value in digitalization. Ax*1 is a distance increment obtained from digital measurement of the web position x1, for example by means of a pulse transmitter.In the case illustrated in
Figure 3a a quantifying error of 10% is tolerated for the web position xl*. To this end it is necessary to provide at least 10 x*1 intermediate points between two scanning times Tm - Tom~1. Accordingly, 10 tanular values must be registered for the function Fi between the two scanning times. In addition to calling for a substantial register size the quantifying error becomes particularly serious close to the end time, i.e. close to the cut, because the functions F assume very large values at that position (singular characteristics, polar position of Fi).
Figure 3b represents that case in which the scanning points are defined as equidistant location points. The scanning points are defined simply by counting, for example of every 10 distance increments Axl* (scanning width AN). Since the scanning points N, N+1 etc. are defined a priori the function values will be sufficient only for the said scanning points N,
N+1 etc. Accordingly, only a tenth of the amount of memory space is required for each function generator compared with the case illustrated in Figure 3a. The solution function
Fi.k can be stored as step functions in the form of solutions Di,N where i = 1, 2, 3 and N is the number of the scanning point.Apart from the substantially reduced memory requirements the case according to Figure 3G is also free of quantifying errors, a feature which is most marked in terms of increased accuracy close to the cutting point.
Figure 4 shows the block diagram of a digital regulating system for a cross-cutter in which the process features, namely that the scanningpoints for the measured values of the process quantities are defined by positions of the material web, for example by means of marks on the material web, are also utilized for the construction of the function generators 3, 4 and 5.
The solutions Di of step curves in the form of register tables instead of the solution functions F are then stored in the function generators. In addition to the regulating system shown in
Figure 2 a counter 11 is also provided the input of which is supplied with measured values of the distance increments Axl of the web position x1. The number N of the locationdependent scanning points N appears at the output of the counter 11. The stored tabular registers for the solutions Din place of the constant function Fj are substantially smaller.
The input of the digital regulating system according to Figure 4 is therefore provided with three function generators 3, 4 and 5 which contain the solution functions Fi in the form of tables for the solutions Di and are driven by the counter 11 which is indexed in accordance with the conveying position x, of the material web. The function generators 3, 4 and 5 are connected to the multipliers 6, 8 9 and 10 for multiplying the output quantities of the functions 3, 4 and 5 by the measured values of standardized process quantities xl, x2, v, and v*.
Figure 5 shows a digital regulating system for a cross-cutter in which only the positions x2 and x, of the knife drum and material web can be measured as process quantities by counting distance increments Ax,* and Ax2. By contrast to the embodiment illustrated in
Figure 4 the multipliers 8 and 10 at the output of the regulating system are combined into a further multiplier 12. A squaring unit 13 is connected between the process quantity v,* and the multiplier 12. A further counter 14, connected to the measured value of the position x1 of the material web and two counters 15 and 16, connected to the measured value of the position x2 of the knife drum. are provided at the input of the regulating system.In this construction only the distance increment Ax2 of the knife position x2 traversed during the preceding scanning interval N ... N-l, i.e. during the location-dependent scanning interval
AN, is required as measured value and not the knife drum or knife velocity v2. Like the value of x this quantity can be obtained by the counter 15 which counts the distance increments Ax2. This obviates the problematic measurement of the substantially variable knife velocity v2. Mere counting of the distance increments (pulses) Ax,* and Ax2 of the web position (location) and knife position (angle) remain since the relatively slowly variable web velocity vT can be derived from the counter 14 which counts the web pulses due to the distance increments Ax, during a constant time AT. The counter 16 counts the distance increments Ax* in the form of pulses while the material web continues to move forward by
AN. The counter 15 counts the pulses from the knife drum in absolute terms. Altogether, no separate velocity measurement is necessary in the digital regulating system according to
Figure 5.
The tables for the solution values Di in the function generators 3, 4 and 5 of the regulating systems according to Figures 4 and 5 represent a relationship between the serial number N of the scanning point and the solution or function value Dj,N, they do not depend on the absolute value of the quantity xl*. The relationship between x*1 and N, i.e. the relationship expressing the number of distance increments A?1 which form a scanning interval N, is established by preceding standardization, the procedure for performing such standardization being known.
Figure 6 is a graph which discloses that the same numbers N occur with different standardization in different regions of the entire transition interval. If the entire interval between consecutive cuts is divided into individual phases the length of each of which takes the form of a geometrical series 1/bm and if the standardization in each phase varies in proportion with the phase length only a fraction of the tabulated values normally required will be sufficient for the function generators 3, 4 and 5.According to Figure 5 different standardization coordinates different scanning points N and therefore solutions Dj,N to a physical location x1 or different physical locations are coordinated to a scanning point N and therefore to a solution Dj N. The entire interval between consecutive cuts of the regulating system is therefore divided into individual phases the length of each of which takes the form of a geometrical series (1/by) and standardization of the measured values is altered in proportion to the length of each phase.
Figure 7 shows in diagrammatic form a case with the base b = 2 for the geometrical series, which is particularly advantageous in dual arithmetic where m = 4 phases P1, P2, P3, and P4. The residual phase RP is also stated. The entire range is therefore divided into phases in accordance with the geometrical series 1/2". The individual phases adjoin each other without overlap and gap and the scanning intervals become progressively shorter. It can be seen that for the scanning width selected for phase P4 a total of 64 tabulated values or solutions Dj are required for each function generator and of these the tabular values 5 to 8 are required in phase P4.
If the scanning width in the phase P3 is doubled by a change of standardization, i.e. if twice as many distance increments Ax are associated with a scanning interval AN it will be possible to utilize the tabulated values 5 to 8 instead of the tabulated values 9 to 16 in phase
P3. This also applies to phases P2 and P1 in relation to the preceding phase P3 and P2. The residual phase RP can also be subdivided by continued restandardization so that the tabular values 5 to 8 apply in place of the tabular values 1 to 4. A reduction of tabular values from 64 to 4 is therefore obtained in the example illustrated in Figure 7 and this applies to each of the three function generators 3, 4 and 5.
A very coarse subdivision is shown in Figure 7 in the interests of clarity. A substantially finer subdivision, for example 30,000 scanning intervals, is used in the practical embodiment of phase subdivision and restandardization. It can readily be seen that the saving of memory space is exceptionally high.
Figure 8 shows the characteristic of the solution Di with and without subdivision of the interval between consecutive cuts. The characteristic without subdivision is shown in broken lines. It will be seen that the solutions Di without subdivision assume very large values close to the cutting point and a very large dynamic range Di max - Dj min occurs. A wide dynamic range leads to inaccurate representation, more particularly of small values, due to the rounding-off error if a given digital word length displays the numbers. The dynamic range Di max - Dj min in all phases is the same small dynamic range obtained by subdivision. An increase of accuracy in computing the control functions can therefore be achieved by subdivision.
In deriving the above-mentioned synthesis equations it was assumed that the knife drum drive has a double integral characteristic. The control function u will then correspond to the acceleration b1 of the material web. The acceleration b1 will be a straight line, the web velocity v, a parabola and the web position x, will be a cubic parabola. Actual drives exhibit such ideal characteristics only in a rough approximation and for this reason end value regulating circuits for such drives have a high degree of sensitivity to disturbances, more particularly close to the cutting point. According to one further development, a mathematical model of this section of the interval is simulated in generating the control function, making use of partial products, and is used for precise guidance of the knife drum drive.To this end the digital regulating system 17 contains a mathematical model 19 of the section in addition to the end value regulator 18. Such a regulating circuit structure is illustrated in Figure 9. The supplementary indices s or i in the process quantities indicate the set points or measured values of these quantities.
According to Figure 9 the actual end value regulator 18 of the digital regulating system 17 acts on the mathematical model 19 of the section as well as on the current regulator 20 of the drive motor 21 for the knife drums to provide the set point current value i2S.
The knife position x2* at the output of the mathematical model 19 is proportional to the set point value x2 of this knife position and is supplied to a position regulator 22. The position regulator 22 receives the measured knife position value x2j from the output of the drive motor 21. The knife position x2 is also supplied to the end value regulator 18. The knife velocity v2* is proportional to the set point velocity v25 of the knife and is supplied from the output of the mathematical model 19 to the input of a speed regulator 23 as well as to the end values regulator 18. The speed regulator 23 receives the measured knife velocity value v2 from the output of the drive motor 21.The input of the speed regulator 23 is finally also supplied with the output quantity of the position regulator 22. The speed regulator 23 operates into the current regulator 20, the input of which is also supplied with the control function u*, which is proportional to the current set point value i2s, and with the measured current value i2i from the out put of the drive motor 21.
The set point value vl, of the web velocity is supplied to the drive motor 24 for the feed of the material web. The web position xl is picked off from the drive motor 24 and converted by means of a pulse transmitter 25 into the distance increment Ax1. This distance increment Axl for the web position xl is again supplied to the end value regulator 18. The mathematical model can be particularly easily integrated into the regulating system already described since partial products, by means of which the model can be particularly simply and accurately simulated, already occur kn the digital regulating system or in the end value regulator 18 when the control function u* is defined.The digital regulating system therefore provides not only the control function u* as the set point acceleration but also the knife position x, and the knife velocity v2* as the set point position or set point velocity. Precise guiding of the knife drum drive is thus made possible. A conventional position regulating circuit with a subordinate velocity and current control is used for the knife drum drive itself.
Position regulation of the knife drum can also be performed in the digital regulating system to which end the position regulator 22 is integrated into the digital regulating system 17 is illustrated in Figure 10.
It is here that the set point value v,5 of the knife velocity for the speed regulator 23 appears directly at the output of the position regulator 22. Only a conventional speed and current control drive of the knife drum is required with a digital regulating system constructed in this manner.
Furthermore, the set point value is advantageously specified in the digital regulating system for the feed of the material web. To this end a unit 26 for additional super-ordinate functions contains a unit 27 for specifying the set point value of the web velocity, which said unit is integrated into the digital regulating unit 17 which supplies the set point value vl5 of the web velocity to the drive motor 24 for the material web feed. A regulating circuit structure of this kind which corresponds to the regulating circuit structure according to
Figure 10 with the exception of the unit 26 integrated into the digital regulating system 17, is illustrated in Figure 11.Depending on the cutting format or on the sheet length the set point value vls of the web velocity can then be computed in optimum terms by the digital regulating system 17 with the integrated unit 26.
The run-up to speed of the cross-cutter can also be controlled by the digital regulating system by providing a corresponding unit for controlling the run-up in the unit 26. Finally, the digital regulating system 17 can perform additional superordinate functions if corresponding units are provided within the general scope of the unit 26 which is integrated into the digital regulating system 17. Such units include a unit 28 for optimizing, a unit 29 for adaptation, a unit 30 for monitoring and a unit 31 for format control, all within the unit 26. By means of such units the digital regulating system 17 can perform the superordinate functions of cutting fault monitoring and correction by adaptation, cut counting (sheet counter), format control, even from cut to cut, or in dependence on the desired sheet length without interruption and signalling and/or documentation of operating states.
WHAT WE CLAIM IS:
1. A method of controlling the drive motor of two knife drums which are coupled to each other and are associated with a cross-cutter for material webs, with a purely digital regulating system arranged to generate a control function in dependence on measured values of process variables, such as position and velocity of the material web, the scanning points for the measured values of the process variables, such as position and velocity of the material web and position and velocity of the knife drums being defined by positions of the material web and the control function being generated by means of function generators and multipliers.
2. A method as claimed in claim 1, in which the scanning points are defined by marks on the material web.
3. A method as claimed in claim 1 or 2. in which only the positions of the knife drum and material web are detected as process variables by counting of distance increments.
4. A method as claimed in any one of claims 1 to 3, in which the entire interval between
**WARNING** end of DESC field may overlap start of CLMS **.
Claims (20)
1. A method of controlling the drive motor of two knife drums which are coupled to each other and are associated with a cross-cutter for material webs, with a purely digital regulating system arranged to generate a control function in dependence on measured values of process variables, such as position and velocity of the material web, the scanning points for the measured values of the process variables, such as position and velocity of the material web and position and velocity of the knife drums being defined by positions of the material web and the control function being generated by means of function generators and multipliers.
2. A method as claimed in claim 1, in which the scanning points are defined by marks on the material web.
3. A method as claimed in claim 1 or 2. in which only the positions of the knife drum and material web are detected as process variables by counting of distance increments.
4. A method as claimed in any one of claims 1 to 3, in which the entire interval between
consecutive cuts of the regulating system is subdivided into individual phases the length of which constitutes a geometrical series of the form 1/bm and standardization of the measured values is altered in each phase proportional to the phase length.
5. A method as claimed in claim 4, in which b = 2 is used as basis for the geometrical series.
6. A method as claimed in any one of claims 1 to 5, in which a mathematical model of distance is simulated in the regulating system when the control function is simulated, with the use of partial products, and is employed for precisely controlling the knife drum drive.
7. A method as claimed in claim 6, in which the position of the knife drum is also regulated by the digital regulating system.
8. A method as claimed in claim 6 or 7, in which the set point for the advance of the material web is specified in the digital regulating system.
9. A method as claimed in any one of claims 6 to 8, in which the run-up of the cross-cutter is controlled by the digital regulating system.
10. A method as claimed in any one of claims 6 to 9, in which superordinate functions are additionally performed by the digital regulating system.
11. A digital regulating system for performing the method of claim 1, in which two knife drums are coupld to a controlled drive motor and arranged as a cross-cutter for material webs, the three function generators are provided at the input of the system and contain solution functions Fi in the form of tables for solutions Dj, and three function generators being connected to be driven by a counter which is arranged to be stepped in accordance with the position of the material web, the function generators being connected to multipliers for multiplying the output variables of the function generators by the measured values of the process variables and for generating the control function.
12. A digital regulating system as claimed in claim 11, in which only the solutions Di for one phase of the interval between consecutive cuts, subdivided into phases the lengths of which correspond to a geometrical series of the type 1/bm, are stored in each of the function generators.
13. A digital regulating system as claimed in claim 11 or 12, in which an additional counter, connected to receive the measured value of the position of the material web, and two counters, connected to receive the measured value of the position of the knife drum are provided at the input.
14. A digital regulating system as claimed in any one of claims 11 to 13, containing a mathematical model of distance in addition to an end value regulator.
15. A digital regulating system as claimed in claim 14, further containing a position regulator.
16. A digital regulating system as claimed in claim 15, containing a unit for computing the speed set point for a drive motor associated with the material web.
17. A digital regulating system as claimed in claim 15, containing a unit for controlling run-up to speed of the cross-cutter.
18. A digital regulating system as claimed in claim 15, 16, or 17, containing units for performing additional superordinate functions.
19. A method of controlling the drive motor of two knife drums which are coupled to each other and are associated with a cross-cutter for material webs, substantially as hereinbefore described with reference to the accompanying drawings.
20. A digital regulating system for performing the method of claim 1, substantially as hereinbefore described with reference to any one of the embodiments illustrated in the accompanying drawings.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE19782812849 DE2812849C2 (en) | 1978-03-23 | 1978-03-23 | Method for controlling a cross cutter and digital control device for carrying out the method |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| GB1602480A true GB1602480A (en) | 1981-11-11 |
Family
ID=6035349
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB2577578A Expired GB1602480A (en) | 1978-03-23 | 1978-05-31 | Method for controlling a cross-cutter and digital regulating system for performing the method |
Country Status (2)
| Country | Link |
|---|---|
| DE (1) | DE2812849C2 (en) |
| GB (1) | GB1602480A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP1839858A3 (en) * | 2006-03-28 | 2011-03-30 | manroland AG | Folding apparatus of a printing press and method for operating the same |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE10213978A1 (en) * | 2002-03-28 | 2003-10-09 | Roland Man Druckmasch | Process for cross cutting a running web |
Family Cites Families (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB844486A (en) * | 1958-01-01 | 1960-08-10 | Cossor Ltd A C | Improvements in or relating to arrangements for controlling the lengths into which fed material is cut |
| US3181403A (en) * | 1962-08-03 | 1965-05-04 | Logic Systems Inc | Control system |
| US3232157A (en) * | 1963-06-21 | 1966-02-01 | Allis Chalmers Mfg Co | Digital control for shear |
| DE2020199B2 (en) * | 1970-04-25 | 1974-02-21 | Jagenberg Werke Ag | Cross cutter with controlled multi-motor drive for cutting sheets of the same length |
| GB1385053A (en) * | 1972-01-18 | 1975-02-26 | Masson Scott Thrissell Eng Ltd | Rotary drive controls |
| SE7601676L (en) * | 1975-02-18 | 1976-08-19 | Strachan & Henshaw Ltd | SYSTEM FOR CUTTING PRINTED PAPER OR FILM MATERIAL |
| DE2747022C2 (en) * | 1977-10-19 | 1985-05-15 | Siemens AG, 1000 Berlin und 8000 München | Circuit arrangement for the electrical direct drive of a rotating separating device |
-
1978
- 1978-03-23 DE DE19782812849 patent/DE2812849C2/en not_active Expired
- 1978-05-31 GB GB2577578A patent/GB1602480A/en not_active Expired
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP1839858A3 (en) * | 2006-03-28 | 2011-03-30 | manroland AG | Folding apparatus of a printing press and method for operating the same |
Also Published As
| Publication number | Publication date |
|---|---|
| DE2812849A1 (en) | 1979-09-27 |
| DE2812849C2 (en) | 1985-01-24 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PS | Patent sealed | ||
| PCNP | Patent ceased through non-payment of renewal fee |