JPS6269896A - Texture improving apparatus of twin wire type papermaking machine - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to a device for improving the formation of paper in a twin-wire paper machine that makes paper by sandwiching paper raw material between upper and lower wires. .

(Prior Art) FIG. 3 shows an example of a conventional twin wire former, which is said to have good fiber dispersion and therefore good paper formation. The paper raw material liquid 2 ejected from the head box 1 lands on the lower wire 3 and forms the forming board 4, a plurality of foils 5,
Dehydration is performed in a vacuum foil box 6 or the like, and the concentration of the raw material gradually increases. Furthermore, the raw material is top unit 1
The upper wire 19 whose running direction has been reversed by the top lead-in roll 8 of No. 8 is sandwiched between the upper and lower wires 19 and 3 on the lead-in box 9.

The sandwiched raw material is dehydrated by pressing pressure generated by the wire tension of the upper wire 19 on a plurality of shoes 10 installed. Further push roll 11
After the dewatering progresses, the wet paper is transferred to the lower wire 3 in the transfer suction box 13, dehydrated in the suction box 14 and the suction couch roll 15, and is big-amplified by the suction pickup roll 16 and transferred to the next press process. be done. The upper wire 19 and the lower wire 3 are endless, and are changed direction and cleaned by the wire turning rolls 12 and 17 in preparation for the next dehydration.

According to research conducted by the present inventors, the formation of this type of twin-wire former is due to pressure cavities generated in the raw material due to the part where the raw material is sandwiched between the two wires and the pressing pressure after the sandwiching. The pressure gradient (hereinafter referred to as pressure gradient) has a large influence, and if this pressure gradient is set appropriately, the raw material liquid will be decelerated and accelerated in the advancing direction without stirring, and the formation will be greatly improved. I found out what I can do. The pressure gradient for this deceleration and acceleration depends on the machine speed, basis weight, raw material composition, concentration in that state, etc.
Hereinafter, these will be referred to as operating conditions. ), its appropriate value changes.

FIG. 4 is an enlarged view of the shoe 10 portion. Conventionally, as shown in the figure, the shoe body 20 is composed of a shoe body 20 and its support body 21, and the shoe body 20 is fixedly attached to the support body 21. Since the radius of curvature of the arc formed from the wire guide surface made up of the plurality of shoe bodies 20 is always constant, the pressing pressure P is determined by P = - (T: wire tension, R: radius of curvature), so the wire The tension T was adjusted to make the pressing pressure P a predetermined pressure. However, there is a limit to the circumference of the wire tension δ, and as mentioned above, the radius of curvature of the wire guide surface created by the shoe body 20 is constant, so if operating conditions change due to paper change etc.
The above-mentioned pressure gradient was outside the appropriate value range and there was a tendency for the condition to deteriorate.

(Problems to be Solved by the Invention) As mentioned above, in the wire part of the conventional twin wire paper machine, the radius of curvature of the wire guide surface formed by a plurality of shoes is constant, so the operating conditions The problem was that when there was a change in the pressure, an appropriate pressure gradient could not be set, resulting in poor formation.

The present invention has been made with this point in mind, and it is an object of the present invention to provide a device that can always set an appropriate pressure gradient and can significantly improve the formation.

(Means for Solving the Problems) Therefore, the present invention provides a formation improving device installed in a wire part of a twin-wire paper machine in which papermaking raw materials run between two wires, which A means for solving the above-mentioned problems is provided by means that are connected to each of the shoe blades and can arbitrarily change the radius of curvature of the arc of the shoe blade during operation.

(Function) The curvature of the wire guide surface created by the plurality of shoes can be changed as desired in whole or in part, and the pressure gradient between the two wires, which changes depending on the operating conditions, is always maintained at an appropriate value. .

(Example) Embodiments of the present invention will be described below based on the drawings.

FIG. 1 is a partially omitted sectional view showing the overall structure of a shoe portion according to this embodiment. Portions other than those shown in the drawings are the same as the conventional device shown in FIG. 3, so their explanation will be omitted here.

In FIG. 1, reference numeral 21 denotes a support disposed near the confluence of the two upper and lower wires 26 and on the downstream side. Shoeplay I! 23 are arranged in parallel in the width direction of both wires 26. As shown in FIG. 2, the shoe blade 23 is supported by a bracket 25 in which a blade moving device 24 such as a pneumatic/hydraulic cylinder or a flexible tube is housed. The lower part of the bracket 25 is fitted and fixed to the upper surface of the support body 21 .

When the protrusion amount of these shoe blades 23 is individually changed by the blade moving device and the curvature of the wire guide surface formed by the shoe blades 23 is changed, the wrap angle of the upper and lower wires is also changed. Become. In order to adjust the ramp angle, a push roll 27 that can move up and down and back and forth is arranged downstream of the plurality of shoe blades 23.

In this embodiment having the above configuration, when the operating conditions change, the radius of curvature of the arc formed by the plurality of shoe blades 23 can be changed by individually moving each shoe blade 23 in the radial direction. , to maintain the pressure gradient between the two wires at a proper value. A blade moving device 24 consisting of an air cylinder, a hydraulic cylinder, a flexible tube, etc. is attached to each shoe blade 23, so that by adjusting the pressure supplied to it, each shoe blade 23 moves in the radial direction. The radius of curvature of the arc formed can be set arbitrarily. Since the supply pressure can be adjusted externally, even during operation it is possible to:

(1) The radius of curvature of the arc formed by a plurality of shoe blades can be set arbitrarily.

(2) The curvature of the arc formed by a plurality of shoe blades can be made into a combination of compound curvatures.

(3) The pitch of the shoe blade can be set arbitrarily.

In this example device, the raw material concentration in the wire part is 0.8 to 3.
．． 5%, the radius of curvature R of the arc formed by a plurality of shoe blades is preferably 1 to 5 m, and the wire tension T is 10 to 30 PCI. The pressure gradient between the two wires can always be maintained at an appropriate value, so that good formation can be maintained.

Although the plurality of blade moving devices mentioned above act individually, they are managed so that they can be controlled in total by a control device (not shown), and can be controlled even in response to changes in operating conditions during normal operation. , it is also possible to make it possible to follow immediately.

(Effects of the Invention) As described above in detail, according to the present invention, the shoe blades can be moved in and out independently, and the curvature of the curved surface formed by the plurality of shoe blades can be changed entirely or partially. Since it can be changed, it is possible to always set the pressure gradient in the dewatering section of the wire part to an optimal value, and the formation of papermaking can be further improved.

[Brief explanation of drawings]

Fig. 1 is a partially omitted cross-sectional view of a soil improvement device showing an embodiment of the present invention, Fig. 2 is a cross-sectional view showing the support structure of a single shave blade of the same device, and Fig. 3 is a twin-wire paper machine wire. A schematic side view of the part, and FIG. 4 is a sectional view showing a conventional shoe. Description of main parts of the figures 21 - Support 23 - Shoe blade 24 - Blade moving device

Claims (1)

[Claims] This is a formation improvement device that is installed in the wire part of a twin-wire paper machine where papermaking raw materials run between two wires, and is connected to a plurality of shoe blades, each of which adjusts the radius of curvature of the arc of the shoe blade. A formation improvement device for a twin-wire paper machine characterized by having a means that can be changed arbitrarily during operation.