JP2515857Y2 - Drying cloth with adjusted air permeability - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to a drying cloth which is hung in a single line form in a drying section of a paper machine.

(Prior Art) In the drying section of a paper machine, a needle dryer made by polymerizing and monomerizing a fibrous web on a textile dryer canvas or a textile base cloth, which is woven with warp and weft, is generally used. . The drying cloth of the present invention refers to both of them. The drying cloth runs on the heating cylinder along with the wet paper one after another to dry and transport the wet paper.

In the conventional drying device, the single run type drying method, in which one drying cloth is wound around the upper and lower heating cylinders, has been generalized because it can handle high speeds, and especially the front side of the drying group, that is, the wet side. Used in.

In the single run method, the machine speed is good up to about 800 m / min, but when it exceeds 1000 m / min or more, the wet paper leaves the canvas at the entrance of the lower cylinder, and it is easy for flaps and wrinkles to occur again. Therefore, auxiliary means are needed to stabilize the running. That is, by installing a blow box (FIG. 2), a negative pressure is generated in the nip portion P between the canvas and the drying cylinder, and the wet paper is attracted to the drying cloth to stabilize the traveling. The details of the blow box are described in JP-A-63-6192 and others.

(Problems to be solved by the device) However, it is very difficult to control the suction degree of the blow box in the width direction, and the paper quality, the basis weight, the machine speed,
It must be adapted to various conditions such as moisture content, and in some cases the sheet may bulge away from the drying cloth at the widthwise ears.

This is because the vacuum pressure in the ears is easily reduced due to the mechanical structure, and although it is considered from the viewpoint of the device, it is not perfect. Also, as the use progresses, dirt substances tend to adhere to the surface of the drying cloth, and the air permeability tends to decrease, but this degree is worse in both ears than in the center. Therefore, the suction degree of the blow box becomes imbalanced.

(Means for Solving the Problem) The present inventor has devised a solution to this from the aspect of a drying cloth (hereinafter referred to as a canvas), and changes the air permeability in the width direction of the canvas so that the air permeability of the canvas is changed. Was solved by making both ends larger than the central part.

(Function) Since the air permeability in the width direction of the canvas is larger than that in the center of the ear, the force of sucking the wet paper through the canvas is large even if the suction of the blow box is low, and the wet paper and the canvas are closely attached. The running of the wet paper web is sufficiently stable. Also, since the suction force is great even when the tail passes through the paper, it can be securely held by the carrier rope or the like.

(Example) The present invention will be described below with reference to the drawings.

FIG. 1 shows a canvas 1 of the present invention, which is made of woven fabric or needle nonwoven fabric. FIG. 2 shows a part of a single run dry group having a blow box 7. The wet paper web 5 runs under the canvas 1 in the upper heating cylinder and around the canvas in the lower cylinder along with the canvas. In the vicinity of the nip P in which the wet paper sheet enters the lower cylinder, there is a tendency for air pressure to swell to the outside, which causes flapping and wrinkling of the sheet. Therefore, the blow box 7 sucks the air in the nip portion to form a negative pressure to prevent this phenomenon.

Both ends 3 and 3 of the canvas have a higher air permeability than the central part 2. The width of 3 is generally about 30 to 100 cm, and the air permeability is set about 10 to 20% higher than the center. However,
It is not limited to this condition.

The methods for increasing the air permeability are as follows: (1) The warp density of the woven fabric is adjusted by reducing the warp density at both ends. (2) Use a thin warp.

However, in both cases (1) and (1), the strength of the selvages should not be reduced in consideration of the material of the warp. (3) Central part 2
Resin is coated only on the part to block the texture a little.

In the case of a non-woven fabric, the air permeability is adjusted by using a woven fabric whose air permeability is adjusted as a base fabric, or after laminating webs, the air permeability is increased by punching holes at both ends with a laser beam.

The air permeability of both ears can be increased by using various other methods.

(Effect of the device) As described above, the present invention enables the wet paper to be reliably adsorbed to the canvas at the point where it moves to the lower cylinder, and even at high speeds of 1000 m / min or more, wet paper ballooning, fluttering and wrinkling can be prevented. This eliminates the occurrence of this and makes it easier to adjust the degree of vacuum in the blow box and stabilizes the running of the wet paper web. In addition, it makes it easy to pass through the tail, which helps improve operability.

[Brief description of drawings]

FIG. 1 is an explanatory view of a drying cloth of the present invention, and FIG. 2 is an explanatory view showing a part of a single run type drying group. 1: Drying cloth, 2: Central part, 3: Both ends, 5: Wet paper, 6: Heating cylinder, 7: Blow box

Claims (1)

(57) [Scope of utility model registration request] 1. A drying cloth for hanging in a single run system, wherein the cloth has an air permeability that is larger than the central portion at both ends in the width direction.