Textiles: knitting – Needles – Sliding latch
Reexamination Certificate
2000-03-27
2001-05-22
Worrell, Danny (Department: 3741)
Textiles: knitting
Needles
Sliding latch
C066S123000
Reexamination Certificate
active
06233977
ABSTRACT:
CROSS REFERENCE TO RELATED APPLICATION
This application claims the priority of German Application No. 199 13 822.2 filed Mar. 26, 1999.
BACKGROUND OF THE INVENTION
This invention relates to a compound needle particularly for use in loop-forming textile machines.
Knitting machines and similar loop-forming textile machines use compound needles whose hook may be closed by a closing element. The closing element is guided and controlled in such a manner that it may move onto and away from the needle hook for securely maintaining the threads captive in the needle hook. Further, the closing element can close the hook to allow the loop to glide on its exterior (knockover step). In case the closing element is displaced further outwardly beyond the hook, the loops transferred to the closing element may be taken over by other needles (loop transfer step).
Loop-forming textile machines must form the desired loops with the highest degree of reliability. Even only sporadic operational defects immediately spoil the quality of the produced fabric to an unacceptable extent. Further, the loop formation has to occur at a high speed to ensure an acceptable output rate. The loop-forming process, despite the high speed, must not be affected, to the greatest extent possible, by operational disturbances such as changing pulling forces exerted on the thread caused, for example by the predetermined pattern, non-uniform thread thickness or other influences.
Further, the compound needles should be exposed to as little wear as possible to ensure a reliable operation over a long service period, and to keep maintenance periods and down times relatively short.
U.S. Pat No. 1,673,634 discloses a compound needle having a divided closing element. The closing element is composed of two thin, resilient sheet metal closing element parts coupled to one another. The two closing element parts are, as a unit, longitudinally displaceably mounted in a closing element slot which is provided in the needle shank and which begins in the vicinity of the needle hook. The two free terminal leg portions of the closing element projecting from the closing element slot define a funnel which receives the tip of the needle hook when the closing element has been shifted to a position in the vicinity of the needle hook. For this purpose, the two free leg portions of the closing element are slightly bent away from one another. In addition, the leg portions are constructed such that they tend to resiliently move away from one another as they emerge from the closing element slot.
SUMMARY OF THE INVENTION
It is an object of the invention to provide an improved compound needle having a greater operational reliability than conventional compound needle structures.
This object and others to become apparent as the specification progresses, are accomplished by the invention, according to which, briefly stated, the compound needle includes a shank having an end; a hook formed on the shank at the shank end and having a hook tip; and a closing element slot provided in the shank and being defined by two parallel shank flanks. The closing element slot extends from a location adjacent the hook in a direction away therefrom. The compound needle further has an elongated closing element received in the closing element slot for longitudinal sliding motions therein. The closing element has a hook-closing position in which the closing element is situated in an immediate vicinity of the hook tip. The closing element is composed of at least two side-by-side disposed, resilient closing element parts each having a free terminal leg oriented toward the hook. The terminal legs are bent away from one another to define a funnel having an open end oriented toward the hook and a beginning spaced from the open funnel end. The closing element parts are bent away from one another from the beginning of the funnel in a rearward direction away from the hook for resiliently contacting respective slot flanks at contact locations. The contact locations are situated adjacent the beginning of the closing element slot when the closing element is in its hook-closing position.
The compound needle according to the invention has a divided or slotted closing element which is conventionally composed of two or more closing element parts. Embodiments are feasible in which the closing element is formed of a single slotted component.
The closing element parts or closing element regions separated by a gap are biased resiliently away from one another in the installed state. In this arrangement not only the leg portions which form the funnel are resiliently moving but also the parts or regions adjoining the funnel. This is achieved by a lateral resilient bulging of the closing element parts which at other locations are connected fixedly with one another or constitute a one piece component. In the region which adjoins the funnel, the closing element parts are, however, not connected with one another to ensure that they may move resiliently freely away from one another. The curvature of the two closing element parts is designed such that the zones thereof which immediately adjoin the funnel are in contact with the flanks of the closing element slot. The thus-obtained bilateral locations of contact form guiding or supporting locations for the closing element and thus center it in the closing element slot.
The guiding and supporting locations are situated very close to the free end of the closing element as a result of a suitable bend of the closing element parts. If the closing element is in the hook-closing position, the regions of the closing element which form the contact locations are situated in the zone of the beginning of the closing element slot. The contact locations of the closing element are situated such that when the closing element is in the loop transfer position, that is, it is shifted outwardly beyond the needle hook, at least portions of the contact locations project from the closing element slot. In an embodiment of the invention such contact locations of the closing element already reach the beginning of the closing element slot when the closing element assumes its knockover position. Preferably, however, these regions already reach the beginning of the closing element slot as the closing element assumes its hook-closing position.
By the particular bending of the closing element parts a small distance between the contact locations and the free end of the closing element is obtained. This makes possible an accurate guidance of the free end of the closing element and thus the formation of a very narrow funnel. An accurate guidance of the closing element at or in the compound needle makes possible a secure introduction of the hook tip into the funnel even if the funnel mouth is very narrow. Even in case of forces which are laterally exerted on the free ends of the closing element, for example, a lateral thread pull, the closing element legs which define the funnel are not deflected to such an extent that upon closing the needle hook they would collide with the hook tip; in this manner wear is reduced.
Further, a narrow funnel ensures a secure gliding of the loops over the hook during knockover which, similarly to a secure opening and closing of the closing element, enhances the operational reliability.
A further advantage is derived from the reduction of the funnel size by improving the guidance of the closing element in the closing element slot. A smaller funnel provides for a low-friction run of the closing element in the closing element slot, particularly when the funnel enters into the closing element slot upon withdrawing the closing element. This arrangement, in turn, makes possible to design the closing element slot to be relatively narrow, that is, the play between the closing element and the closing element slot can be minimized. A small play, in turn, increases the positioning reliability and thus the operational reliability of the compound needle.
By virtue of the bend in the closing element parts according to the invention, the closing element is centered in the c
Ruoff Klaus
Schuler Bernhard
Groz-Beckert AG
Kelemen Gabor J.
Venable
Worrell Danny
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