Textiles: weaving – Weft manipulation – Weaving with stationary weft supply
Reexamination Certificate
2001-02-26
2002-04-09
Falik, Andy (Department: 3765)
Textiles: weaving
Weft manipulation
Weaving with stationary weft supply
Reexamination Certificate
active
06367515
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to a rapier loom comprising at least one rapier for driving a gripper which is held by fastening means and of which the center of gravity is situated above the top side of the rapier, further comprising a batten bearing a reed and fitted with guiding means comprising guiding surfaces for the rapier, which are associated with the side of the top side of the rapier away from the reed, with the bottom side of the rapier and with the side surfaces of a downward-pointing rib.
2. Description of the Related Art
A rapier loom of the initially cited kind is used by applicant in the rapier looms it is marketing at the present time. Its design corresponds essentially to that of U.S. Pat. No. 5,413,151. A guide element is mounted in extension of the rapier and a gripper is affixed at the longitudinal center of said element. The width of this guide element corresponds to that of the rapier and on its side away from the reed, the guide element is fitted with a downward pointing rib. The guide element and the rapier are guided by hook-shaped guiding means mounted on the batten and open to the reed. The hook-shaped guiding means are fitted with guiding surfaces associated with the top side of the guide element and of the rapier as well as with the bottom side of the guide element and of the rapier. Another guiding surface is associated with that side surface of the rapier and the guide element which is away from the reed. Further guiding surfaces guide the rib of the guide element in the transverse direction, as a result of which the guide element together with the gripper is guided omni-directionally. This design operates reliably. However a problem arises in that in this design, and in fact in any other design used in practice, strong wear takes place rapidly and entails replacing the guide element.
In another practical design, for instance known from U.S. Pat. No. 4,834,146, hook-shaped guide elements are mounted on the batten and almost wholly enclose the top and bottom sides of the rapier. The bottom side of the rapier is fitted with a longitudinal channel engaged by guidance of the hook-shaped guides as a result of which the rapier shall also be guided transversely. Because the hook-shaped guides almost completely enclose the rapier, the gripper is affixed laterally to the rapier. This lateral gripper affixation to the rapier entails substantial transverse stresses on the rapier, especially during decelerations/accelerations, and as a result relatively heavy wear materializes. Once a given degree of wear has taken place, this design requires exchanging the full rapier.
In order to circumvent the wear and other drawbacks of the design disclosed in U.S. Pat. No. 4, 834,146, the European patent document 0,709,505 A1 discloses replacing the hook-shaped guides with two different kinds of guides, one of said kinds of guides being associated with the top side of the rapier and the guides of the other kind being associated with the bottom side of the rapier. While this design allows grinding the guides of the two guide devices, the drawback remains that the gripper is mounted laterally and accordingly also the entailed transverse stresses.
In order to avert the transverse stresses of the design of U.S. Pat. No. 4,834,146 and of the European patent document 0,709,505 A1, the European patent document 0,715,009 A1 discloses guiding only the bottom side of the rapier by means of guide elements and to mount the gripper centrally on the top side of the rapier. The gripper elements engage a channel in the bottom side of the rapier. The gripper must be designed so that its center of gravity coincides with that of the rapier or shall remain below it. However this document fails to disclose how to configure a gripper so that its center of gravity shall coincide with, or be below, that of the rapier.
It is known also from U.S. Pat. No. 5,183,084 to allow a partly overlapping motion of a rapier with a gripper affixed centrally to its end with that motion by which the guides are inserted into the shed. This design employs two kinds of guide devices, one of which is fitted with only one guide for the bottom side of the rapier and the other with a guide for an upper side edge, a side surface and a guideway for the edge zone of the bottom side. In this design, the rapier is supported only at its bottom side across a large part of its displacement, and there is danger as a result especially when accelerating/decelerating, that the rapier shall rotate about its longitudinal axis, in particular when high speeds are desired.
SUMMARY OF THE INVENTION
The objective of the invention is to improve a rapier loom of the initially cited kind so that wear shall be reduced.
The invention solves this problem in that the guide surface of the guiding means associated with the top side of the rapier extends over more than one third the width of the rapier and in that the gripper fastening means are mounted offset relative to the longitudinal center plane of the rapier in the direction towards the reed.
The invention is based on the insight that the main cause of wear are forces generated in particular when accelerating/decelerating the gripper head of which the center of gravity is situated above the top side of the rapier, whereby said forces tend to rotate the rapier and if present a guide element extending the rapier and carrying the gripper, about the longitudinal axis. Accordingly the invention calls for guides opposing the rapier rotation which are designed with most advantageous possible leverage to act on the rapier in order to reduce the forces entailing rotation. In particular this shall be the guide acting on the rapiertop side, which shall advantageously act on the rapier if extending over more than a third the width of the guide element and of the rapier, possibly as much as half. In order that nevertheless the gripper position shall remain unchanged, the gripper fastener(s) shall be mounted in such shifted manner that adequate space is available for the guide to act.
In an advantageous embodiment of the invention, the rib is mounted a distance from the rapier's side surface which is away from the reed. Appropriately and furthermore, the guiding means shall be fitted with guiding surfaces on each side of the rib for the bottom side of the rapier. By shifting the rib toward the center of the rapier, a space of the bottom side of the rapier and/or of the guide element is created in particular on rib side away from the reed to which a guiding surface is associated which shall oppose rotation by means of an advantageous leverage and hence by means of comparatively low forces.
Further advantages and features of the invention are elucidated in the following description of illustrative embodiments and sub-claims.
REFERENCES:
patent: 4777989 (1988-10-01), Pezzoli
patent: 5806570 (1998-09-01), Speich
Bacon & Thomas PLLC
Falik Andy
Picanol N.V.
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