JPH0640625A - Control method for web guide device - Google Patents

Abstract

PURPOSE:To facilitate the control of the quantity of flotation in a web guide device whose peripheral face opposite to a web is provided with a plurality of air blowing out holes and slits by controlling the quantity of flotation of the web based on pressure between the web and the peripheral of the device and pressure inside the device. CONSTITUTION:In a web guide device 2 which floats up a film and the web 3 of a thin steel belt or the like by blowing out air for carrying and leading them, the air supplied through a duct 4 from a fan 6 is blown out through a plurality of holes and/or slits which are formed on the peripheral face of the device. In this case, a valve 5 to regulate the quantity of blown out air is interposedly provided in the duct 4, and its opening is controlled by a computing element 1, which is provided with measuring holes for the internal pressure Pi and back pressure Pb in the web guide device 2, and the number of revolutions of the fan 6 and the valve 5 are controlled on the measured internal pressure Pi and back pressure Pb so that pressure parameter [ (Pi-Pb)/Pb ]<1/2> may be kept constant, and the quantity of flotation can be thereby controlled to be constant.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a web guide device for levitating and transporting a web of paper, film, thin steel strip or the like. More specifically, the web guide device accurately controls the web flying height. The present invention relates to a control method of a web guide device that can be performed.

[0002]

2. Description of the Related Art In a web guide device for levitating and transporting a web, the blowout pressure and air volume of air necessary for levitating the web from the guide device have been conventionally set mainly by the following three methods. . The discharge pressure and air volume are set so that the required levitation is ensured even at the maximum web tension. Set the discharge pressure and air volume according to the normal tension of the web. The web tension and flying height are monitored, and the pressure and air volume at each tension are controlled.

[0003]

However, when the pressure and the air volume are set by the above, that is, when the pressure and the air volume are set in accordance with the maximum tension of the web, the flying height at the low tension becomes too large. However, this method has a problem in that the energy efficiency is poor, and that the flying height fluctuates due to tension in this method. Also, when setting the pressure and air volume according to the normal tension as in the above, there is a problem that the web does not float at a high tension, the web contacts the relevant device, and the fluctuation of the flying height is unavoidable. there were. When controlling the web tension and flying height as described above, a tension detection sensor and a flying height measurement sensor must be installed in addition to the relevant device.
Further, in order to control the flying height, it is necessary to control the internal pressure or the flow rate by the rotation speed of the fan or the damper. When performing such control, it is necessary to grasp and control the three relationships of tension, flying height, and internal pressure as shown in FIG. Therefore, the present invention provides a method for controlling a web guide device in which the floating amount of the web is always an appropriate value even if the tension of the web changes, and it is an object of the present invention to solve the above-mentioned conventional problems.

[0004]

Therefore, the present invention provides a guide device for a web having a plurality of holes and / or slits for blowing air on the peripheral surface facing the web, between the web and the peripheral surface of the apparatus. The present invention is characterized in that the amount of levitation of the web from the device is controlled based on the pressure (back pressure) and the internal pressure of the device (internal pressure). To do.

[0005]

In the present invention, the relationship between the pressure parameter and the flying height is on one straight line even if the tension changes. In this case, the opening degree of the damper is controlled so that the pressure parameter is constant, and the flying height is controlled to be constant. Therefore, the flying height is determined by one regression line in any tension state, so that the flying height can be easily controlled.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will now be described with reference to the embodiments of the drawings. In FIG. A web guide device, 3 is a web, 4 is a duct for supplying air to the web guide device, 5 is a valve for controlling the air volume in the duct 4 based on the result of the arithmetic unit 1, and 6 is for supplying air. A fan and web guide device 2
A plurality of holes and / or slits for blowing air are formed on the peripheral surface facing the web 3. Further, the web guide device 2 includes an internal pressure Pi and a back pressure Pb of the web guide device.
Measuring holes (not shown) are provided so that the pressure of air can be measured by these holes.

Here, between the internal pressure Pi, the back pressure Pb and the flying height h,

[Equation 1] It is known that there is a relationship of K: constant. Therefore, in the present invention, the pressure parameter, that is,

[Equation 2] Is calculated by the arithmetic unit 1 so as to be kept constant, and the rotation amount of the fan 6 or the valve 5 is controlled based on the result, whereby the flying height h can be controlled to be constant. FIG. 2 shows the relationship between the pressure parameter and the flying height of the web guide device used in the embodiment according to the present invention. As is clear from FIG. 2, even if the tension changes from T _{1 to} T ₃ , the relationship between the pressure parameter and the flying height is on one straight line. In this case, the opening degree of the damper 5 is controlled so that the pressure parameter is constant, and the flying height is maintained constant. Further, FIG. 3 shows a graph of the flying height when the tension is changed, but as is clear from FIG. 3, according to the present invention, it is always constant when the tension is changed. The flying height is obtained.

[0008]

As described in detail above, according to the web guide apparatus of the present invention, the flying height is determined by one regression line in any tension state, so that the flying height can be easily controlled. It has an excellent effect.

[Brief description of drawings]

FIG. 1 is a system diagram of a web guide device according to an embodiment of the present invention.

FIG. 2 is a diagram showing a relationship between a flying height and a pressure parameter according to an embodiment of the present invention.

FIG. 3 is a diagram showing a relationship between a change in tension and a change in flying height and time according to the embodiment of the present invention.

FIG. 4 is a diagram showing the relationship between the flying height and the internal pressure.

[Explanation of symbols]

 1 calculator 2 web guide device 3 web 4 duct 5 valve 6 fan

Claims (1)

[Claims] 1. A guide device for a web having a plurality of holes and / or slits for blowing air on the peripheral surface facing the web, wherein the pressure between the web and the peripheral surface of the device (back pressure) and the inside of the device. A method for controlling a web guide device, characterized in that the flying height of the web from the device is controlled based on the pressure (internal pressure).