JPH0647796B2 - Paper thickness profile controller - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to improvement in controllability of profile control in a paper thickness profile control process device of a paper machine.

(Prior Art) An outline of a papermaking process will be described with reference to FIG. The raw material pulp P merges with the return raw material from the white water silo 3 through the seed box 1 and the seed valve 2, and is supplied to the head box 5 by the pump 4. The raw material in the head box is discharged in a sheet form on the wire part 8 from the gap of the slice lip 6, squeezed by the press part 9, heated and dried by steam in the dry part 10, and then passed through the calender 11 and reeled. It is wound up on 12 and becomes a product. Reference numeral 7 is a plurality of (for example, 60) slice bolts for operating the gap of the slice lip.

Reference numeral 13 is a B / M meter that scans the product in the paper width direction to measure the basis weight, moisture content, and paper thickness of the paper. Based on these measurement values, the absolute dry basis weight, moisture content, and paper thickness of the paper The profile measurement values PV ₁ , PV ₂ and PV ₃ are calculated by dividing the paper widthwise direction into a plurality of points, for example 360 points.

Profile measurement value P of absolutely dry basis weight of each point calculated
The difference between V ₁ and the set value SV ₁ is control-calculated by the profile control device 14, and the slice opening 7 corresponding to the measurement point is operated by the operation output MV ₁ to adjust the lip opening to obtain the absolute dry basis weight profile of the product. The feedback control is performed so that is equal to the set absolute dry basis weight profile.

Similarly, the difference between the profile measured value PV ₂ and the set value SV ₂ of the moisture content at each point calculated is the profile controller 1
The feedback control is performed such that the moisture content profile matches the set profile by operating the heater output in the profile control device realized by the infrared heater 101 corresponding to the measurement point by the control calculation by the operation output MV _2. Be seen.

Similarly, the difference between the profile measured value PV ₃ and the set value SV ₃ of the paper thickness at each point obtained by calculation is the profile control device 14
The control output is calculated by the operation output MV _3, and the roll gap is adjusted by operating the operation end of the calender corresponding to the measurement point, and feedback control is performed so that the paper thickness profile of the product matches the set profile.

A man-machine interface 15 communicates with the control device 14 and has a profile display function.

The present invention relates to improvement of paper thickness profile control among the three types of profile control.

FIG. 5 is a partially enlarged view of the calender roll 11, which is an actuator for manipulating the thickness of the paper. The calender roll 111 pressing the paper 16 output from the calender is spaced at a constant interval (for example, 60 mm) along the paper width direction P. The actuators 17 ₁ , 17 ₂ , 17 ₃ ... Are arranged opposite to the rolls.

There are various types of actuators, such as a type in which electromagnetic waves are supplied to a roll by a coil to expand the portion by heat from an eddy current, and an expansion and contraction type in which hot air and cold air generating nozzles are used.

FIG. 6 shows a correspondence relationship between a plurality of paper thickness measurement points (for example, 360 points) n and a plurality of zones m which each actuator takes charge of. The measurement points of are mechanically assigned.

In this example, three measurement points are assigned to one zone. The relationship between zones and measurement points is as shown in the table below.The average value of the measured values in each zone is used as the measured value in that zone, the deviation from the set profile is calculated, and the operation amount of that zone is calculated by the control calculation based on this deviation. Is calculated.

FIG. 7 is a functional block diagram of a paper thickness profile control system, 18 is a position correspondence and deviation processing function, 19 is a velocity type PI calculation function for deviation calculated for each zone,
20 is a non-interference algorithm processing function that compensates for interference between adjacent operation ends, 21 is an optimum paper edge output signal processing function that predicts and estimates the measurement value of the paper edge portion and generates an apparent operation output, and 22 is all This is an output average value optimization processing function that performs bias processing on each operation output signal so that the average value of the operation output becomes constant.

(Problems to be solved by the invention) With such a configuration, the profile control of the paper thickness in the steady state is executed, but recently, the number of actuators has increased to meet the demand for fine profile control (for example, 100
Book), therefore the width of one zone is becoming narrower.

For this reason, even if the operation amount for one zone is changed, the change in paper thickness is small. As a result, the control gain is insufficient at the time of starting to make the paper, at the start after the paper is cut, and it takes a long time to settle the profile.

An object of the present invention is to provide a paper thickness profile control device capable of solving such a problem by a simple means.

(Means for Solving the Problem) The present invention that achieves such an object is to provide a plurality of actuators attached to a calender roll as operating ends based on a deviation between a measured value and a set value of a paper thickness profile of a paper machine. And a roll gap for controlling the paper thickness profile, which has the following configuration.

That is, after the settling position correspondence table (table) in which the paper thickness profile measuring points in the paper width direction corresponding to each operation end of the actuator are defined, and a plurality of operation ends of the actuator are zoned, and each zone is supported. And a pre-settling position correspondence table in which paper thickness profile measurement points in the paper width direction are set.

Then, the correspondence between the paper thickness profile measurement points and the plurality of actuators is selectively changed using the both position correspondence tables according to an operator's instruction or a settling state of the paper thickness profile.

(Operation) A plurality of actuators attached to the calendar roll are driven by operation outputs calculated based on the deviation between the measured value and the set value of the paper thickness profile of the paper machine.

The post-settling position correspondence table is suitable for finely controlling the paper thickness profile and describes the profile measurement points corresponding to one operating end. The pre-settling position correspondence table is suitable for roughly controlling the paper thickness profile and describes the profile measurement points corresponding to the zoned operating ends.

If fine control is performed using the pre-settling position correspondence table at the start of operation, the time until settling is shortened and the loss of paper is reduced. After settling, the post-settling position correspondence table is used for fine control to obtain a more uniform paper thickness profile.

(Embodiment) An embodiment of the present invention will be described based on the functional block diagram of FIG. The same elements as those described with reference to FIG. 7 are designated by the same reference numerals, the description thereof will be omitted, and the description of the characteristic portion of the present invention will be added.

Reference numeral 23 is a sequence means, which changes the correspondence between the profile measurement points and the actuators by a command Y to the position correspondence processing function 18. It is activated by this command operator's manual operation input C ₁ or the signal C ₂ from the profile monitoring means 24.

That is, when the profile is not stable (the deviation is large) and the control gain is insufficient, the position correspondence is manually or automatically changed.

The following table shows an example of correspondence changes.

That is, the actuators in the adjacent zones are simultaneously operated by the operation output based on the deviation due to the group of the same measurement points. With such an operation method, the control resolution is reduced, but the control gain can be increased.

FIG. 2 is a flow chart showing a signal processing procedure for explaining the operation of the present invention. When the profile is stable, a control calculation with high resolution is executed by the same positional correspondence as shown in the table. If the profile is not stable, the control operation is changed to the correspondence relationship based on the table, and the control gain is increased.

Here, the table is referred to as a post-stabilization position correspondence table, and the table is referred to as a pre-settlement position correspondence table. The post-settling position correspondence table is suitable for finely controlling the paper thickness profile and describes the profile measurement points corresponding to one operating end. The pre-settling position correspondence table is suitable for roughly controlling the paper thickness profile and describes the profile measurement points corresponding to the zoned operating ends.

FIG. 3 shows a comparison of the control amount with the conventional control based on such a change in the correspondence relationship. In comparison with the change amount of the paper thickness in the conventional individual zone independent control shown in FIG. It can be seen that the amount of change in paper thickness significantly increases when simultaneously operating adjacent zones shown in B).

In the above embodiment, the simultaneous operation of adjacent zones has been described, but it is also possible to operate two or more zones at the same time.

Further, the input to the sequence means is, in addition to the input of the embodiment,
You can enter the factors that require a transient increase in the control gain, such as when the printer starts or when the paper runs out.

Further, the table defining the correspondence is a man-machine means 1
5, it is easy to make maintenance possible, and a versatile paper thickness profile control device corresponding to the brand can be realized.

(Effects of the Invention) As described above, according to the present invention, when the profile of the paper thickness is not stable (the deviation is large), the operation in which the resolution in the width direction is not good but a large control gain is obtained can be performed. It is possible and the profile settling time can be shortened. Therefore, it is possible to perform an operation in which the occurrence of waste paper can be reduced, and it is possible to contribute to the improvement of the controllability of the paper thickness profile control of the paper machine.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an embodiment of the present invention, FIG. 2 is a flow chart diagram showing a signal processing procedure for explaining the operation,
FIG. 3 is a characteristic diagram for comparing a control amount with a conventional control device, FIG. 4 is a conceptual diagram of a control device of a paper machine, and FIG. 5 is a configuration diagram of an actuator portion for paper thickness profile control,
FIG. 6 is an explanatory diagram showing the correspondence between the measurement points and the zones of the actuators, and FIG. 7 is a functional block diagram showing an example of the prior art of the paper thickness control system. 18 ... Position correspondence processing function, 19 ... Speed type PI calculation function, 20 ... Interference algorithm processing function 21 ... Optimal paper edge output signal processing function, 22 ... Output average value optimization processing function, 23 ... Sequence Means, 24 ... Profile monitoring means

Claims (1)

[Claims] 1. An apparatus for controlling a paper thickness profile by a roll gap by operating a plurality of actuators attached to a calendar roll as operating ends based on a deviation between a measured value and a set value of a paper thickness profile of a paper machine. , A post-settling position correspondence table (table) in which paper thickness profile measurement points in the paper width direction corresponding to each operation end of the actuator are set, and a zone is formed by a plurality of operation ends of the actuator,
Pre-settling position correspondence table (table) in which paper thickness profile measurement points in the paper width direction corresponding to each zone are defined
According to the operator's instruction or the settling condition of the paper thickness profile, the correspondence between the paper thickness profile measurement point and the plurality of actuators can be selectively changed using the both position correspondence tables. Characteristic paper thickness profile control device.