Textiles: knitting – Needles – Shanks
Reexamination Certificate
2000-02-09
2001-10-09
Worrell, Danny (Department: 3741)
Textiles: knitting
Needles
Shanks
Reexamination Certificate
active
06298693
ABSTRACT:
CROSS REFERENCE TO RELATED APPLICATION
This application claims the priority of German Application No. 199 05 668.4 filed Feb. 11, 1999, which is incorporated herein by reference.
BACKGROUND OF THE INVENTION
This invention relates to a transfer needle for loop-forming machines making flat textile knitwear.
For making, for example, patterned knitwear, circular knitting machines with cylinder needles and dial needles may be used. Dependent on the pattern, individual loops are transferred from the cylinder needles to the dial needles and conversely. For this purpose special needles are used which have loop transfer elements and are designated as transfer needles.
German Patent No. 42 31 015 discloses transfer needles configured as compound needles which have a slide extending longitudinally along the needle shank and serve for opening and closing a hook (head) carried by the needle shank. A transfer spring secured to the side of the compound needle defines with the needle shank an intermediate space through which the hook and the shank of another needle may pass. The transfer spring is held only at one of its ends on the needle shank. For a suitable configuration of the intermediate space between the transfer spring and the needle shank the latter is provided with a recess which intersects the slide as well as the shank.
The intersecting faces of the slide and the shank each form guide faces which are to facilitate the penetration of another needle into the intermediate space.
German Patent No. 1,560,996 discloses a transfer needle which is configured as a latch needle rather than a compound needle. Accordingly, it has a solid needle shank without a slide element. To effect loop transfer, the latch needle has a laterally bent shank. That part of the shank which extends from the hook and which is designated as the main shank is of stepped structure having a high and a low portion. Starting from the low portion, a groove extends over the needle back to the high shank portion in which the groove is entirely open towards the side face of the needle.
A lateral bent portion of the shank is, however, in many instances undesirable.
German Patent No. 31 45 708 discloses a transfer needle for flat knitting machines. The needle has a transfer spring on its side for transferring the loops. The spring is a leaf spring and is affixed at one of its ends to the needle shank. The other, free end of the leaf spring forms, together with the needle shank, an intermediate space into which another needle may penetrate with its hook and shank. The leaf spring as well as the needle shank are, at their respective underside, provided with an oblique guide face which is intended to facilitate the penetration of another needle into the intermediate space between the transfer spring and the needle shank. The guide face provided on the shank is substantially planar and extends from the needle back to the outer side face of the needle.
Particularly the transfer spring of the transfer needle is exposed to substantial dynamic loads during operation. For the loop transfer first the hook and one part of the shank of another transfer needle enters the intermediate space in the vicinity of the free end of the transfer spring. This event may already cause the free end of the transfer spring to be pushed away laterally from the needle shank at which the transfer spring is secured. If such an occurrence takes place in a narrow needle guide channel where the transfer spring lies against the channel flanks, the transfer spring may undergo substantial local bending deformations which lead to high stresses. If such an occurrence causes breakage of the spring, the transfer needle becomes useless, and the knitting machine has to be stopped for servicing.
SUMMARY OF THE INVENTION
It is an object of the invention to provide an improved transfer needle of the above-outlined type whose service life is lengthened.
This object and others to become apparent as the specification progresses, are accomplished by the invention, according to which, briefly stated, the transfer needle for loop forming machines includes an elongated needle shank having a needle back, an outer side face and a top face opposite the needle back; a transfer spring attached to the needle shank and defining an intermediate space therewith; and a lateral recess provided in the needle shank and forming part of the intermediate space. The recess is defined by a guide face extending from the needle back to the outer side face of the needle shank. The guide face includes a first length portion bordering the outer side face of the needle shank and extending toward the needle back; and a second length portion bordering the needle back and extending toward the outer side face of the needle shank. The first and second length portions of the guide face meet in an obtuse angle which is open toward the transfer spring.
Thus, the transfer needle according to the invention has at its side face a recess which is covered by a transfer spring. The transfer spring is, at one of its ends, connected with the needle shank and has a preferably pointed tongue which lies in a depression of the needle shank. The recess positively defines a guide face at the needle shank along which a penetrating hook of another needle may slide. The guide face extends along the recess from the needle back to the lateral needle face, while its angle formed with the needle back changes. Stated differently, the guide face has a first portion adjoining the needle back and a second portion adjoining the lateral needle face, and the two portions form an obtuse angle with one another, whereby the guide face is concave. This measure prevents an excessive weakening of the needle shank in the region of the recess. This measure also permits an enlargement of the depth of the recess compared to conventional configurations without causing an excessive weakening of the needle shank. Also, the displacement/time relationship concerning the excursion of the transfer spring may be positively affected, and a spring breakage is prevented which could otherwise occur as a result of dynamic loads on the transfer spring, particularly in the region of its free end. The service life or service expectancy of such a transfer needle is thus lengthened.
The transfer needle according to the invention may be configured such that the guide face forms, in vicinity of the needle back, a small angle with the principal direction of motion of a penetrating transfer needle. In this manner a penetrating transfer needle is relatively slowly deflected laterally and is relatively gradually accelerated. Thus, not only the transfer spring but also the penetrating transfer needle is gently handled.
Due to the particular configuration of the guide face, in the transfer needle according to the invention a smooth transition from the upper side (top face) of the needle to the outer side face thereof for forming the loop support edge is not affected. The depth of the penetration space, however, may be enlarged. The recess may be configured such that it terminates at the side face of the transfer needle. By virtue of this arrangement, in this region the loop supporting edge may configured without a profile change caused by the recess. This ensures that the loops glide gently and without damage over the loop supporting edge.
The concave shape of the guide face may be obtained in various ways. For example, the guide face may be at least partially arcuate in the longitudinal direction of the transfer needle. Additionally, the guide face may be at least partially arcuate or kinked at least once in a direction defined by the penetrating motion of another transfer needle. The curvature may be circular, parabolic or of any other shape. In any event, the recess may be deeper than it has been possible heretofore without adversely affecting the loop supporting edge or the stability of the loop forming region of the transfer needle. It has been found that the depression, compared to transfer needles having a linear guide face could be deepened by 0.1 mm at the hei
Groz Beckert KG
Kelemen Gabor J.
Venable
Worrell Danny
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