JPH0121251B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION This invention relates to a shedding method for a loom, and in particular to an improvement in a shedding method that creates a dwell difference between upper and lower warps and creates a tension difference between the upper and lower warps due to a difference in shedding amount during beating. be.

It is widely known that in order to weave a high-quality woven fabric without reeds, it is effective to apply an appropriate tension difference between the upper and lower warps during beating. Conventionally, two methods have been generally employed to provide such a difference in tension between the upper and lower warps.

The first method is the warp maximum shedding amount difference method, in which the upper and lower warp yarns have the same dwell but have a difference in their maximum shedding amounts. This is shown in FIG. In the figure, the opening amount of the warp yarns A and B is plotted on the vertical axis, and the crank angle is plotted on the horizontal axis, which corresponds to the warp line on the loom. The textile structure cited is 1/1. Dwell of upper and lower warps with DA
In DB, the maximum opening amount is shown as HA and HB, and the opening amount when hitting the reed is shown as HA' and HB'. In the case shown, DA=DB
And since HA<HB, HA'>HB' and (HA'-HB') is the difference in opening amount when hitting the reed. As a result of such an opening difference, an appropriate tension difference occurs between the upper and lower warp yarns during weft beating, and the purpose of preventing the formation of reeds is achieved.

However, in this method, since the maximum opening amount of the upper warp threads is small, the tension of the upper warp threads at the time of maximum opening is naturally low.
Therefore, the handling of the warp threads becomes poor. In other words, the upper warp does not follow the movement of the heald frame quickly,
It takes time to form a complete shed. This leads to a corresponding reduction in the time available for weft insertion, which is not desirable in terms of stabilizing weft insertion. On the other hand, if the maximum shedding amount HA is increased in order to make the upper warp thread tension at maximum shedding appropriate, the maximum shedding amount HB of the lower warp threads must also be increased due to the above-mentioned relationship HA < HB. As a result, the lower warp tension at maximum opening becomes too high, which is undesirable.

The second method can be called a dwell difference method, in which the maximum opening amount of the upper and lower warp threads is the same, but the dwells are made to differ. This is shown in FIG. In the case shown, DA<DB and HA=
Since HB, HA′>HB′ and (HA′−
HB') is the difference in shedding amount during weft striking, and as in the case of Fig. 1, an appropriate tension difference is obtained between the upper and lower warps during weft striking. Moreover, since the maximum shedding amount HA of the upper warp threads is equal to the maximum shedding amount HB of the lower warp threads, the tension of the upper warp threads at the time of maximum shedding is also sufficiently high, and the warp handling is also improved. That is, the drawbacks of the warp maximum shedding amount difference method as shown in FIG. 1 are solved.

However, in this method, the lower warp yarns with a long dwell DB are exposed to high tension for a long time in the maximum open state, so the fatigue of the warp yarns is so severe that it is easy to cause warp breakage.

The purpose of this invention is to reduce the risk of warp thread breakage, which is a drawback, while maintaining the superiority of the warp dwell difference method over the maximum shedding amount method as described above.

In the invention for this purpose, at the time of shedding, a maximum opening amount sufficient to improve yarn handling is given to both the upper and lower warp threads, and then the opening amount of at least one of the warp threads is returned to the level necessary for weft insertion. , to move on to the next opening movement.

Some embodiments of this invention are shown in FIGS. 3-6. The solid line in the figure shows the case according to this invention,
The dashed line shows the case using the conventional dwell difference method.
The textile structure is 1/1 in the case of Figs. 3 to 5, and 2/1 in the case of Fig. 6.

In the case shown in Figure 3, only for the lower warp,
Once the opening amount is set to the maximum, the opening amount is returned to the amount necessary for weft insertion, and that opening amount is maintained for a certain period of time.

In the case shown in Fig. 4, only for the lower warp,
Once the opening amount is set to the maximum, it is gradually returned to the opening amount necessary for weft insertion.

In the case shown in Figure 5, for the upper warp, once the shedding amount is set to the maximum, the shedding amount is gradually returned to the amount necessary for weft insertion, and for the lower warp, the shedding amount is once set to the maximum amount and then the opening amount necessary for weft insertion is returned. The opening amount is returned to the original opening amount and maintained at that opening amount for a certain period of time.

In the case shown in FIG. 6, both the upper and lower warp threads are once set to the maximum shedding amount, then returned to the shedding amount necessary for weft insertion, and maintained at that opening amount for a certain period of time.

The method of return, such as which of the upper and lower warp threads should be returned, whether both should be returned, whether they should be returned in stages, or whether they should be returned in a gradual manner, should be combined as appropriate depending on the conditions such as the type and thickness of the warp threads. Just set it.

The shedding motion of the warp threads is normally provided by a cam that is linked to the main shaft of the loom, and the one shown in FIG. 7 is an example of a cam used to perform the shedding as shown in FIG. 5. The dashed line is used in the conventional dwell difference method (1/1).

As is clear from the above, in this invention, the upper and lower warp yarns are given the maximum shedding amount for the time being, which improves the handling, and if necessary, the shedding amount is then returned to the amount required for weft insertion, so that the warp yarns can be left open for a long time. Under the excellent condition that no tension is applied, an appropriate tension difference can be applied between the upper and lower warp yarns during weft beating to prevent the occurrence of reed marks.

[Brief explanation of drawings]

FIG. 1: A diagram showing the aperture according to the conventional maximum aperture difference method. FIG. 2; Diagram showing an aperture according to the conventional dwell difference method. Figures 3 to 6; Diagrams showing apertures generated by the dwell difference method. FIG. 7: A side view showing an example of a cam used in the opening method of the present invention. DA, DB...Dwell, HA, HB...Maximum opening amount HA', HB'...Aperture amount when hitting laterally.

Claims (1)

[Scope of Claims] 1. A method of applying a tension difference between the upper and lower warps due to a difference in shedding amount during weft beating by a dwell difference between the upper and lower warps, which is sufficient to once improve thread handling for both the upper and lower warps at the time of shedding. A shedding method for a loom, characterized in that after giving a maximum shedding amount, the shedding amount of at least one warp thread is returned to a level necessary for weft insertion, and then the next shedding movement is started. 2. The opening method according to claim 1, wherein the opening amount is returned to the above level from the maximum opening amount at once, and the level is then maintained for a certain period of time. 3. The opening method according to claim 1, wherein the opening amount is gradually decreased from the maximum opening amount to the above level.