JP3010372B2 - Press felt for papermaking - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an open-end papermaking felt having an improved seam structure.

[Conventional technology]

The press felt for papermaking is preliminarily woven in a tubular weave in a bag weave, and the endless direction, that is, the weft direction is applied to the paper machine as the running direction of the felt on the paper machine. In some cases, the woven fabric is woven so as to have a length equal to the length in the running direction, and the both ends thereof are joined to form an annular felt, which is then put on a paper machine.

In both of the above methods, when the felt is applied to the paper machine, a means for sliding the felt support roll of the paper machine in a cantilever manner outside the machine stand and pulling the felt into the roll from the side of the roll is also adopted. However, in order to apply endless felt to a paper machine, the machine must have a unique structure.

In the case of open-ended felt, it is not necessary to make the roll of the paper machine cantilevered, and the felt used up to that point is cut in the horizontal direction, and one end of the new open-ended felt is connected to the cut part, and The new felt is drawn into the felt run of the paper machine by running the felt. Then, when the new felt is completely passed through the paper machine, the old felt is removed, and the new felt is joined at the open end.

Although the open-end felt facilitates insertion into a paper machine in this way, it also has the following disadvantages.

(1) The strength of the seam is 30 to 40% lower than that of the ground.

(2) Due to the low strength of the seam, it is currently difficult for the open-end type felt to maintain the same life as that of the conventional annular endless felt during normal use.

When inserting the open-end felt, if the space between the loop positions is widened so that the core wire can be easily passed,
The number of loops locked to the core wire is reduced, and the strength of the seam portion is reduced. However, even when the interval between the loop positions is reduced by improving the base fabric structure and controlling in the process, the time for passing the core wire is not different from that of the conventional open-end type felt.

The theoretical formulas cited for the improvement of the base fabric structure are shown below.
The weft in the woven fabric is in the running direction of the felt, and the warp in the woven fabric is in the width direction of the felt. Density) is expressed by the following equation.

Maximum warp density NK · max (book / inch) = [1 / warp diameter dK (mm)] x 25.4 For example, if the warp diameter is 0.52 mm, the maximum warp density is
At this time, the warp is tightly packed without any gap. As is apparent from the above equation, when the weft is straight due to warp bending, the maximum warp density has no relation to the diameter and density of the weft.

The maximum weaving number (maximum density) at the weft weaving limit is expressed by the following equation.

Maximum weft density NS · max (books / inch) = {1 / [dk + ds]} x 25.4 x 2 dk: warp diameter (mm) ds: weft diameter (mm): The above x2 indicates double weft (two layers) Due to the structure, for example, if the weft diameter is 0.43 mm and the warp diameter is 0.52 mm, the maximum weft density is 53.5 yarns / inch (the number of weft yarns is half this).
At this time, the center-to-center spacing between the wefts is dk + ds.
In order to take a warp structure, the maximum number of wefts is affected by the diameter of the warp.

On a machine, the number of warps is limited to some extent due to the thickness of the reed, and therefore the number of warps cannot be extremely increased even if the diameter of the warp is reduced. In contrast, weft yarns
Since the weft is simply driven by skipping the shuttle between the warped warps, it is relatively easy to increase the density to the weaving limit with a heavy loom.

[Problems to be solved by the invention]

In view of the above, it is an object of the present invention to greatly improve the seam strength of an open-end type felt, and to obtain a felt having a longer durability time than conventional endless felts and open-ended felts having a small number of loops. Is what you do.

[Means for solving the problem]

In an open-end felt obtained by needling a bat on a compression-resistant base cloth, the warp and weft threads of the base cloth are formed of monofilaments having a thickness of about 0.48 ± 0.05 mm, and the warp direction is If the weft has a double structure in one of the weft directions and a double structure in the warp direction, the weft will bend,
If there is a double structure in the weft direction, the warp bends, and
The warp has the maximum warp density NK · max (books / inch) = {1 / dk} x 25.4, and the weft has the maximum weft density NS · max (books / inch) = {1 / [dk + ds]} x 25.4x 2 Formula (where dk is the warp diameter (mm) and ds is the weft diameter (mm)), and each of them has a structure that has 80% or more of the maximum yarn density represented. [Example] An embodiment of the present invention will be described below.

This will be described with reference to a press felt organization chart shown in FIG.

The warp 1 and the weft 2 composed of 1a, 1b,... 1n are woven on a loom on a loom to form a base fabric 3 having a double warp structure. The weaving width is set to an appropriate width corresponding to the width of the paper machine when installed on the paper machine.

Then, only the warp 1 is formed at the end of the base fabric 3. The warp only portion can be made by removing the weft from the base fabric after weaving, or by not driving the weft in advance. Every other warp 1a, 1c, 1e of only the warp 1 constitutes a loop 4a, 4c, 4e... N.
The folded ends 5a, 5c, 5e... N are passed through the weft 2 so as to form a predetermined texture. The folded ends 5a, 5c, 5e ... n are
The warp yarns 1a, 1c, 1e,... Constituting the loops 4a, 4c, 4e... N constitute end-to-end portions 5b, 5d, 5f. Also, the end 5n-1 of the warp 1n-1 and the warp
The butting portion 7 may be configured like the end 5n of 1n.

The aligning portion 6 and the abutting portion 7 are appropriately scattered so as not to gather at a specific position.

Similarly, the other end of the base fabric 3 is formed in the same manner as the loop 8a, 8b,... At the end of the warp 1, but the loop 8a is formed by the warp 1a having the loop 4a formed at one end, or is formed adjacent to the loop 8a. The loop 8a may be formed at the end of the warp 1b which did not make a loop at one end, or it may be alternately changed as appropriate, but in any case, every other warp is folded back and the loops 8a, 8b,
Are made and the folded portion is aligned with the end of the adjacent warp to make the aligned portion 6 or the end is joined to form the butted portion 7.

And loops 4 at both ends of the base fabric made as above
a, 4c,... 8a, 8b,... are alternately arranged in parallel from the edge of the base fabric, and the core wire 9 is inserted into the loop in the order of the loops 8a, 4a, 8b, 4c,. Be composed.

FIG. 2 shows a cross section of the base fabric. When the warp diameter is 0.52 mm, the maximum warp is 48.85 yarns / inch.

Next, a second embodiment will be described. This will be described with reference to the organization chart of the press felt shown in FIG.

A weft 2 consisting of 2a, 2b, 2c,..., 2n and a warp 1 weave the base fabric 3 having a double warp structure on a loom on a loom. In this case, the weft direction on the loom is the running direction of the felt on the paper machine. , Form a loop 4a, 4b, 4c,... At the end 5 and are folded back under the double structure, and a loop 8a is formed from the underside of the heavy structure at the other end. , 8b,
8c,... Are formed, and the folded back weft is further extended annularly and connected to the wefts 2a, 2b, 2c at the other end. That is, as shown in the cross-sectional view of the warp (FIG. 4), two loops are formed at both ends while the weft 2 makes two loops. All of these loops are formed on the loom, and the degree of uniformity of the loops is very high. Since the loops are alternately meshed in a straight state, the core wire can be relatively easily inserted. If the diameter of the weft is 0.50 mm and the diameter of the warp is 0.40 mm, the maximum density of the weft is 56.4 yarns / inch.

In both of the above embodiments, the basis weight or the void volume can be adjusted by changing the thickness of the warp yarn. The air permeability and water permeability of the felt can also be adjusted by increasing or decreasing the number of bats placed on the base cloth.

Specific examples of the comparison of the breaking strength between the felt according to the present invention and the felt according to the conventional method are shown below.

Example 1. A seam felt having the above-mentioned base fabric structure was applied to a pickup felt for making high-quality paper. Both the warp and the weft used 2,000-denier monofilaments, and the number of threads reached over 80% of the maximum yarn density, which is the weaving limit. The strength of the seam part of the finished felt, which needs nylon pads on both sides, is 193Kg per inch, which is almost twice as large as 190% of the conventional seam felt with a coarse base fabric structure that has a small number of insets. Increased. Further, the core wire insertion time of the loop portion was set to the same level as the conventional one. It is operated at a papermaking speed of 240 m / min using paper coated base paper (60 to 110 g / m2), and the life is on track in the fourth month.

Example 2. The seam felt having the base fabric structure was applied to the bottom felt of the first press. Both the warp and the weft use monofilaments of 2200 denier, and the number of threads is the same as in the above embodiment. When the nylon bat was needled on both sides and the warp strength was measured, the strength of the seam portion of the finished felt was 99.2% of the strength of the ground tissue.

In conventional coarse structures, the strength of the seam area is limited to 55% to 75% at the maximum with respect to the ground part, which is the largest neck that can not extend the life of seam felt.

According to the present invention, the weak point of the connecting portion (seam portion), which is lower in strength than the ground portion, has been successfully overcome. Nip pressure 90kg
When the machine was operated with the paper core of the paper under the machine conditions of 700 cm / min and the paper making speed of 700 m / min, there was no bending of the seam part and the running stability was excellent.

〔The invention's effect〕

The felt of the present invention is an open-end felt obtained by needling a bat on a compression-resistant base fabric, and the warp and weft yarns of the base fabric are formed of monofilaments having a thickness of about 0.48 ± 0.05 mm. The warp direction has a double structure in one of the weft directions, if there is a double structure in the warp direction, the weft bends, if there is a double structure in the weft direction, the warp bends, and The warp has the maximum warp density NK · max (books / inch) = {1 / dk} x 25.4, and the weft has the maximum weft density NS · max (books / inch) = {1 / [dk + ds]} x 25.4x 2 Formula (where dk is the warp diameter (mm) and ds is the weft diameter (mm)), each having a design with 80% or more of the maximum yarn density expressed. The loop density formed at the end of the cloth is woven in a circular shape as a sachet or woven in the longitudinal direction of the loom Even if they are misaligned, the density of the loop forming yarn is 1/2, that is, the former is 1/2 of the weft density, and the latter is 1/2 of the warp density. A loop is obtained at the maximum density when selected. When the loops with the maximum density are aligned in abutting state, the uniformity is good, the passage of the core wire is clearly regulated, and the work can be easily performed when the core wire is passed through the loop. By comparison, the core insertion time does not change much even though the felt itself is hard and dense. In the conventional seam structure, after joining the ends with the core wire, it was necessary to insert a filling yarn to fill the gap so that the seam mark did not stick to the paper, but in the loop near the maximum density, the seam mark was It is no longer necessary to insert a filling thread to prevent the thread from coming out. Therefore, the total loading time into the paper machine can be reduced by 1/3 compared to the conventional case, and when joined with a core wire, the loop density of the joint is large, and the breaking strength of this part is smaller than that of the felt shown in the conventional example. 70-100% can be increased.

[Brief description of the drawings]

FIG. 1 is a structural diagram showing a joint of the first embodiment of the felt of the present invention, and FIG. 2 is a cross-sectional view of the felt of the present invention. FIG. 3 is a structural view showing a joint portion of the second embodiment, FIG. 4 is a sectional view in the meridional direction, FIG. 5 is a sectional view in the weft direction, and FIG. 6 is a structural view of a conventional felt joint. . 1 ... warp, 2 ... weft, 3 ... base cloth, 4, 8 ... loop, 5 ... end, 6 ... pull-out section, 7 ... butting section

Claims (1)

(57) [Claims] 1. An open-end felt obtained by needling a bat on a compression-resistant base cloth, wherein the warp and weft threads of the base cloth are formed of monofilaments having a thickness of about 0.48 ± 0.05 mm. It has a double structure in one of the warp or weft direction, if there is a double structure in the warp direction, the weft bends, if there is a double structure in the weft direction, the warp bends, and A press felt for papermaking having a structure in which the warp is represented by the following formula (1) and the weft is represented by the following formula (2), and the number of yarns is equal to or greater than 80% of the maximum yarn density. Maximum warp density NK · max (books / inch) = {1 / dk} x 25.4 ... (1) Maximum weft density NS · max (books / inch) = {1 / [dk + ds]} × 25.4 × 2 …… (2) where dk: warp diameter (mm) ds: weft diameter (mm)