Textiles: weaving – Warp manipulation – Shedding
Reexamination Certificate
2001-12-19
2003-06-24
Calvert, John J. (Department: 3765)
Textiles: weaving
Warp manipulation
Shedding
C139S011000, C139S055100
Reexamination Certificate
active
06581646
ABSTRACT:
BACKGROUND OF THE INVENTION
On the one hand, this invention relates to a three-position shed-forming device, comprising a shed-forming element provided to be attached at at least one warp yarn on a weaving machine, one set of lifting means with a first and a second lifting means, which are movable up and down over a different lifting height respectively, and a selection device to selectively influence the shed-forming element, so that it may be carried along or not by a lifting means of the set.
On the other hand, this invention relates to a three-position shed-forming device, comprising two shed-forming elements, pulley block device provided for to transmit the movements of both shed-forming elements to at least one warp yarn on a weaving machine, a set of lifting means with a first and a second lifting means, which are movable up and down over a different lifting height respectively, and a selection device, by means of which each shed-forming element may be influenced selectively, so that it may be carried along or not by a lifting means of the set.
This invention more particularly relates to a three-position-jacquard machine, that is provided with a number of the shed-forming devices, indicated in the first and/or second paragraph in order to form a shed between the warp yarns, during the successive working cycles of the weaving machine, each warp yarn each time being brought into such a position with respect to the path of movement of the weft insertion means of the weaving machine, that these warp yarns and the weft yarns inserted into the shed form the fabric desired, according to the given weaving pattern.
With a three-position-jacquard machine the warp yarns may be brought into three possible positions. Moreover, if all these three positions may be realized at each weft insertion on the weaving machine (this means after each half cycle of movement of the blades), regardless of the previous position, this jacquard machine functions according to the open-shed principle.
In this patent application, the three different positions of the warp yarns are indicated as the upper, center and lower positions.
In the German patent DE 41 01 778 C1 a three-position-jacquard machine is described with shed-forming systems with two hooks working together, which are interconnected by means of a pulley block cord and a pulley block suspended in the down hanging loop of the pulley block cord, which is connected to one or more warp yarns via a harness cord. On selection, each hook may be carried along by a blade moving up and down. Two hooks working together are working together with blades moving in opposite phase respectively.
This machine has three-position shed-forming devices of which two of the hooks working together, when selected, are carried along by blades with a different lifting height respectively. By selecting one hook or the other of a pair of hooks working together the warp yarns may be brought into a center or an upper position via the pulley block. When none of the two hooks is selected, the warp yarns connected to the pulley block remain in their lower position, resting on the bottom plank. With these shed-forming devices the three different positions of the warp yarns cannot be reached after each half cycle of movement of the blades. If the blade with the highest lifting height is in its top dead center the upper or lower positions may be reached. If the other blade is in its top dead center the center of lower positions may be reached.
These shed-forming devices have the disadvantage that it is not possible to realize each of the “upper”, “center” or “lower” positions, after having realized the “lower” position after the next half cycle of movement of the blades. Another disadvantage of these shed-forming devices is, that they comprise a pulley block with a pulley block cord. The pulley block cords of a jacquard machine are subject to severe wear because of the friction among them. Moreover, replacing the pulley block cords is time consuming and causes fairly long machine stops.
The jacquard machine from DE-4101778C1 also has three-position shed-forming devices, the two co-operating hooks of which may be carried along by a first and a second blade respectively, each having a same lifting height. The first blade has two hooking on elements provided at a different height, whereas the second blade has only one hooking on element at the level of the upper hooking on element of the first blade. The upper hooking on element is situated near the curved upper extremity of a hook resting on the bottom plank when the first blade is in its bottom dead center. The lower hooking on element is then at a considerably lower level. Therefore one hook is lifted less high when it is carried along by the lower hooking on element than in case when it is carried along by the upper hooking on element. Therefore, depending on the hooking on element chosen, a hook may be brought into two different heights by the first blade, in order to bring the warp yarns in a center position or an upper position. The lower position is realized when both hooks remain in their lowest position on the bottom plank.
Also with these three-position shed-forming devices, the three different positions of the warp yarns cannot be reached after each half cycle of movement of the blades. When the second blade (with one hooking on element) is in its top dead center, only the “upper” and “lower” positions may be reached, when the first blade (with two hooking on elements) is in its top dead center however, the three positions “upper”, “center” and “lower” may be reached.
However, these shed-forming devices present the disadvantage that two controls of the selection device are needed, following each other very quickly, in order to select a hook in such a manner, that it is carried along by the lower hooking on element. A first control of the selection device is needed to bring the hook outside the carrier range of the upper hooking on element. A very short time thereafter, when the blade has been lifted a little, a second control of the selection device is needed to bring the hook within the carrier range of the lower hooking on element. These double controls are causing a considerable consumption of energy. The provisions for the energy supply must, of course, be adapted to that high consumption.
A second disadvantage is, that the hooks which are carried along by a lower hooking on element, are picked up by rising blades which are already fairly high above their bottom dead center and therefore are already in full movement. The non too soft contacts between the lower hooking on elements and the hooks will cause shocks in the jacquard machine as a result of which no high weaving speed can be obtained.
SUMMARY OF THE INVENTION
A first objective of this invention is to realize a three-position shed-forming device of the type with which it will be possible to realize each of the “upper”, “center” or “lower” positions after having realized the “lower” position for the warp yarns, after the next half cycle of movement of the blades, but without the disadvantages mentioned above of the known jacquard machines, more particularly without the use of pulley block elements and with the possibility to realize each position by only one control of a selection element. A further part of this objective is also to provide for a device with which a three-position open-shed-jacquard machine may be composed, using only one pulley block element.
A known three-position open-shed-jacquard machine is described in the European patent EP 0 399 930. In this jacquard machine each shed-forming device has two pairs of hooks. The hooks of each pair may be carried along by blades moving up and down respectively, after they have been brought into a carrier position by a selection device. The blades working together with a pair of hooks are movable in opposite phase. The hooks of each pair are interconnected by a first and a second pulley block cord respectively which, between the hooks, are passed round under the upper pulley block of a respective pulley
Calvert John J.
Creighton Wray James
Muromoto Jr. Robert H.
N.V. Michel Van de Wiele
Narasimhan Meera P.
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