KR810000751B1 - Apparatus for web caliper control - Google Patents

Abstract

Appts. for adjusting the thickness of a paper web (5) passing through a multi-roll calender comprises separate headers supplying hot and cold fluid held under uniform pressure and temp. in each header to nozzles(11) spaced along and directed towards a roll(6). Valves supplying each nozzle are controlled so that a reduction in the flow from one header is accompanied by an increase in the flow from the other so that total flow remains constant. The arrange permits more rapid & precise thickness control with only the temp. being varied. There is a separate mixing chamber between the headers and each nozzle.

Description

Web thickness adjusting device

1 is an air supply system for controlling the major surface portion dimensions of a calender roll at a plurality of major surfaces positioned at even intervals along the length of a calenderroll for the purpose of adjusting the thickness of the web. Schematic perspective view.

2 is a perspective view of a partially cut away portion of the air distribution manifold, ie the assembly of FIG. 1, comprising a header for hot or cold air, a plurality of nozzles, and a corresponding mixing chamber and a valve device connected thereto.

3 is a cross-sectional view of the FIG. 2 assembly showing a device for mixing and distributing hot and cold air.

4 is a partial cross-sectional view taken along line IV-IV of FIG.

5 is a partial cross-sectional perspective view of a portion of the valve structure used in the apparatus of FIGS. 1-4.

6 is a cross-sectional view of a variant embodiment of the air distribution assembly.

7 is a cross-sectional view of another variant embodiment of an air distribution assembly.

FIG. 8 is an operational explanatory diagram of an entire system connected to a calender roll to control web thickness in cooperation with the fluid supply system and other various thickness transducers, transducer computers, and control components shown in FIG.

The present invention relates to a device for adjusting the thickness of a web through a calendar roll and to a calendar comprising such a device.

According to the prior art, hot air or cold air is applied to each longitudinal section of the calender roll from a hot air plenum or cold air plenum in response to a change in the paper web passing through the calender. It is known that the air temperature at the plenum, and the cold air plenum, and the wall of the air supply system connected thereto approaches room temperature while little air is supplied. Thus, with caliper calibration, nozzles that must deliver controlled temperatures of air are at least inadequate for a period of time until the hot or cold air supply system is in equilibrium with the air temperature passing through it. To discharge. This type of operation hinders the rapid calibration of web thicknesses, resulting in poor quality web products.

In the case of the conventional practice, the caliper control made by changing the diameter of a calender roll hits one main surface of the roll with hot or cold air and changes the diameter of the roll by the air collision speed to obtain the necessary effect. It was done in a way. However, the roll diameters on both sides of the corrected main surface were frequently disturbed. The way to correct this was to collide with the main surface portion of the roll to be calibrated, in some cases only cold or hot air. The speed of air changed according to the judgment of driving. According to this conventional method, no air is applied to the roll other than the main surface calibration period.

It is an object of the present invention to provide a method and apparatus which can be more precisely controlled to fit a desired thickness or caliper in the treatment of webs, especially paper webs; To provide a device that responds better to the caliper sensitive mechanism; By continuously flowing air at a standard temperature to keep the main surface of the calender roll uniform, eliminating the need to apply compensating air, ie calibration air, to both sides of the main surface portion of the roll to be calibrated; It is intended to provide a way in which the major surface correction of the roll can be properly made so that the thickness of the web is uniform over the entire length of the roll by only changing one parameter, the temperature of the air coming out of the nozzle.

According to the present invention there is provided an apparatus that can be used with multiple roll calenders and to control the thickness of the web through the calenders, which are arranged at regular intervals to form nozzle rows and, in use, their widths. Multiple nozzles capable of releasing fluid at regular intervals of web portions located throughout the chamber, mixing chambers connected to each nozzle, respective headers for hot and cold fluids, when hot or cold fluids are used Means for maintaining the fluid in the header at approximately uniform pressure and respective predetermined temperature conditions, and a distribution valve connected to each mixing chamber to variably connect each mixing chamber to the two headers individually.

The present invention also provides a method of adjusting the thickness of a web passing through a multiple roll calender which (a) provides for the separate supply of hot and cold fluid media at a uniform pressure in a header adjacent the calender roll. Multiple nozzles capable of holding and (b) forming a jet of fluid medium to impinge these jets into the roll at regular intervals in the length of the roll, and (c) to distribute the hot and cold air in the header, respectively. Various mixtures are formed from 100% cold air to 100% hot air for the nozzles, and the mixture is discharged from the nozzles at a suitable volume and at a pressure common to all nozzles, and (d) hot at each nozzle. Adjust the ratio of fluid to cold to match the diameter of the calender roll to match the diameter of the web through the calender roll. Improving uniformly in the direction.

Hot or cold air supplied to a web thickness control connected to multiple roll calenders can be stored and delivered by plenums, ducts, etc., which can be used to supply each supply system within these plenums or ducts. To the individual mixing chamber. One said mixing chamber is provided with respect to each nozzle of the nozzle manifold arrange | positioned toward a nozzle in the longitudinal direction of a calender roll. The device is capable of releasing a mixture of hot and cold air mixed corresponding to the average thickness at which the web is formed. The device responds to variations in web thickness by, in some cases, impinging a mixture of most hot air or most cold air through the nozzle to the target portion of the roll requiring partial change.

Each nozzle is connected directly to and supplied by a mixing chamber connected to a hot air plenum or a cold air plenum, for example via a distribution device such as a distribution valve. In order for the distribution of hot and cold air to any mixing chamber to be carried out by a relatively simple device, it is desirable to keep the plenums at their respective uniform temperatures and the overall common pressure. With this arrangement, all the nozzles in the manifold continuously discharge air at a substantially uniform flow rate, with each individual nozzle as indicated by the corresponding caliper sensitive device that the thickness of the web deviates from a predetermined value. The temperature of the air coming from will change.

Hereinafter, the present invention will be described in more detail with reference to the accompanying drawings.

1 schematically shows the elements of a fluid supply system which form part of the overall system for automatic web thickness control shown in FIG. 8. 1 shows a web 5 passing through a web thickness sensitive device 8 through calender rolls 6 and 7. In the embodiment shown in FIGS. 1, 2 and 3, the fluid (usually air) dispensing device 10 is arranged in the longitudinal direction of the calender roll 6, and their nozzles 11 ) Projects in the radial direction with respect to the side of the roll 6. The nozzles 11 are arranged at even intervals along the length of the roll 6 so that all fluids exiting it change the temperature of the corresponding diameter portion of the cylindrical surface of the roll 6 which rotates within the protruding portion of each nozzle. Let's go. The distribution device 10 is composed of a plurality of mixing chambers 14 each having one nozzle 11 at its discharge end. The mixing chamber 14 is separated from each other by a vertical wall 15 extending between the outer vertical wall 16 and the inner vertical wall 17.

In the case of the valve arrangement shown, the mixing chamber 14 is connected to the horizontal wall or orifice plate 22 at the bottom by a horizontal wall or orifice plate 18 at the top and from the intermediate chamber 17a of the high temperature chamber. This is separated from the low temperature intermediate chamber, that is, the secondary chamber 21.

The dispensing apparatus 10 also extends along the entire length of the dispensing apparatus and is connected to several secondary chambers 17a through a number of holes 26 formed one for each hot air secondary chamber 17a. An air header 25. The cold air header 28 separated from the hot air header by the wall 29 has a plurality of holes 31 formed one for each of the cold air secondary chambers 21.

The purpose of discharging hot and cold air into the mixing chamber 14 is to provide a constant volume of air into the mixing chamber at all times regardless of the ratio of hot and cold air in the air discharged from the secondary chamber into the mixing chamber. To control the flow from the mixing chamber to the mixing chamber. In general, such an operation will reduce the amount of cold air introduced into the mixing chamber as the amount of hot air introduced into the secondary chamber 17a increases when attempting to increase the temperature of the air discharged from the nozzle. When cooler air is required from the nozzle 11, it is sufficient to increase the flow rate of the cold air from the mixing chamber 12 and reduce the hot air from the secondary chamber 17a.

The adjustment of the air temperature discharged from the nozzle 11 is made by means of a valve device of the type most clearly shown in FIGS. 3 and 5, in which the walls 18 and 22 of the valve device coaxially bore. This opening is adapted to receive an assembly 32 consisting of a pair of cylindrical end closure valve elements 34 and 35 respectively supported in the longitudinal reciprocating valve shaft 33 and in the holes in the walls 18 and 22. .

The valve element 34, 35 is typically a valve element 34 shown in FIG. 5, which extends from the hermetic end 36 and becomes narrower away from the hermetic end 36. It consists of a cylindrical side wall 39 forming 37. The valve elements 34 and 35 are arranged along the rod 33 and in their neutral position a portion of the notch 38 between the teeth of the two elements protrudes into each secondary chamber 17a and 21. Therefore, the same amount of hot and cold air flows from each of the secondary chambers 17a and 21 into the mixing chamber 14. As the valve assembly moves in either direction or the other, the notches formed in the valve element 34 (or valve element 35) are exposed into each adjacent secondary chamber 17a (or secondary chamber 21). Notches in other valve elements are less exposed to each adjacent secondary compartment. Although the valve assembly moves from either secondary chamber to the fully locked position, the amount of air exiting the nozzle 11 through the mixing chamber 14 is maintained at a constant volume.

As one part of the device of the present invention for automatically and individually modifying the position of each valve assembly, at the end of the rod 33 is a small hydraulic spring restoring cylinder Pisoton unit 41. The unit 41 is provided with a restoring spring capable of exhibiting elasticity against a pressure of about 5-30 psi applied to the unit. Since unit 41 preferably reacts extremely sensitive to changes in signal pressure, unit 41 is preferably designed to be as frictionless as possible. It has been found that air cylinders with a stroke length of about one inch are satisfactory for valve motion.

As one embodiment of a system for supplying air to hot and cold air headers 25 and 28, FIG. 1 shows branch lines 45 and 46 directed to respective sub-systems for hot and cold air. A blower 44 is shown for supplying air under pressure. When the hot air is supplied to the header 25, the air is supplied to the heater 48 by the line 45 and through the line 49 to the header 25 for the hot air. In order to keep the header and the air in the header at a constant temperature during the period of inactivity, the hot air system has a recirculation line connected at one end of the header for the hot air and at the inlet of the line 45 to the heater 48. 51 is installed, through which air flows under the influence of the recirculation blower 52. Likewise, air is supplied by the track 46 to the cooler 55 and through the track 59 to the cold air header 28. In order to keep the temperature in the low temperature air header constant, the low temperature air may be recycled in the cooler and the header by the recirculation line 57 and the recirculation blower 58 installed in the line.

As shown, all the nozzles 11 extend radially towards the main surface of the calender roll 6, the calender roll 6 cooperates with the calender roll 7 to advance the web 5 downward in the direction of the arrow. Let's do it. The web leaves the calendar roll and passes through the injection device 8, which in turn uses the electronic device to continuously scan the entire width of the web in a backward and forward manner, thereby providing a computer 60 (known form). Collects web thickness information transmitted into The computer sends an electrical signal to the electronic pneumatic transducer 61. The air signal therefrom is received by a mechanical amplifier 62 which operates synchronously with the scanning device 8. The amplifier 62 has a number of control points 63 that are individually connected to respective corresponding air operated select valves 64, which valve 64 is configured to supply a modulated pressure signal through the pressure regulator 65 to the air cylinder. Transmission to the unit 41 allows the valve assembly 32 to be properly positioned relative to the valve orifice plate 18, 22. Since the pressure in the unit 41 must be reduced when adjusting the valve assembly, the track 66 bypasses the pressure regulator 65 so that air can escape from the cylinder 41 via the four-way selector valve 64. do. Air lines 67 and 68 are connected to separate devices, such as those connected to line 69, to operate each nozzle and valve assembly.

6 shows a variant embodiment of the air distributor 70 consisting of a plurality of walls forming the hot and cold air chambers 71, 72 and a manifold 73 to which the nozzles 74 are attached. The manifold forms a valve chamber 76 and within the valve chamber 76 a partial cylindrical valve element 77 can reciprocate in an arc direction around the point shaft 78, thereby providing a high temperature branch line of the manifold. 81 increases or decreases the air directed to the nozzle 74 while correspondingly reduces or increases the air directed from the cold branch line 82 of the manifold to the nozzle. The proportion of air exiting the branch lines 81 and 82 is automatically controlled by a lever 83 connected to the reciprocating compression rod 85 of the air cylinder 80 by a link 84, whereby the air cylinder 80 Is similar to the air cylinder 41 in the first embodiment. The hot and cold air mixture introduced into the nozzle 74 is automatically controlled by the apertures previously described with the distributor 10.

7 schematically illustrates another variant embodiment of an air distributor 90 consisting of a plurality of walls forming the hot and cold headers 86, 87 and individual mixing chambers 88 for each nozzle 99. Is shown. The mixing chamber is separated from the hot and cold headers by the wall 89 on which the holes 91 and 92 are formed, through which the hot air is introduced into the mixing chamber 88 from the hot header, Through 92, low temperature air is introduced from the low temperature header into the mixing chamber. By the orifice plate 95 in which the holes 96 and 97 having the same diameter as the holes 91 and 92 and having the same diameter are formed, the air passages from the headers 86 and 87 are formed. Adjusted. As shown, the spacing between the holes 96 and 97 is narrower than the spacing between the holes 91 and 92 by a distance corresponding to the diameter of one hole (hole 96 or hole 97). Therefore, when the orifice plate moves to change the air passage from the headers 86 and 87, the orifice plate 95 moves to gradually open another hole while gradually blocking one of the holes 91 and 92. do. The hot and cold air mixture introduced into the mixing chamber exits the distributor 90 through the nozzle 99.

Claims (1)

When the nozzles are arranged at regular intervals to form a row of nozzles, in use, a plurality of nozzles capable of releasing fluid at regular intervals in a wave portion located over the width thereof, a mixing chamber connected to each nozzle, a high temperature fluid and a low temperature fluid Separate headers, means for maintaining high and low temperature fluids in the header at substantially uniform pressure and respective predetermined temperature conditions in use, and each mixing chamber connected to each mixing chamber separately for each of the two headers. An apparatus for adjusting the thickness of a web passing through a calendar, the apparatus being used with a plurality of roll calenders, characterized in that it comprises a distribution valve for variable connection.

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