Textiles: knitting – Independent-needle machines – Straight
Reexamination Certificate
2000-03-22
2001-06-05
Worrell, Danny (Department: 3741)
Textiles: knitting
Independent-needle machines
Straight
Reexamination Certificate
active
06240749
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a flat knitting machine with at least one needle bed and a carriage which is slidable along the needle beds and has at least one cam with needle selection device and stitch cams:
Sinking surfaces on the needle sinkers and the stitch cams position of the cam of a knitting machine determine the form and the size of a stitch. Depending on a knitting type, different stitch sizes and forms are desired. In double-surface R-R knittings, slim stitches of the finest stitch pattern are produced. This is achieved by a small sinking surface on the stitch cams. In single-surface smooth knittings, to the contrary, round stitches of the finest stitch pattern are produced. For producing these round stitches, wide sinking surfaces are required on the stitch cams, so that as many needles as possible are held simultaneously in the deepest sinking position. In this matter the tendency is reduced that the already pulled stitches are pulled from the preceding formed stitches by the produced pulling forces of substantially knit threads and thereby substantially reduce these stitches.
During high grade knitting, in the machine the stitch cams are exchanged when a new knitting must be produced with another binding type. In most cases, however needle sinkers are used which have a central sinking surface and thereby a compromise between the optimal stitch cams sinkers for R-R knitting and a single-surface smooth knitting is formed.
The form of the knitting surface can be also determined as to whether all needles are pulled simultaneously wide during sinking, or in the same needle sinking position they can be pulled differently wide.
In the patent document CH 448 358 a stitch cams is proposed which has two sinking surfaces for producing two different stitch sizes. The same needles which have a higher needle foot are sinking on one sinking surface and the needles with the lower needle feet are sinking on the different sinking surfaces. With the stitch cams, two different stitch sizes are produced, and each size ratio of the stitches are fixed relative to one another and not changeable.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to provide a flat knitting machine, in which an influence of the stitch form and/or size is possible by changing the sinking surfaces without exchanging of the stitch cams.
In keeping with these objects and with others which will become apparent hereinafter, one feature of present invention resides, briefly stated, in a flat knitting machine of the above mentioned general type, in which a sinking element with the stitch cams, which sinking element is arranged movably on the stitch cams, and which depending on the stitch cams is controllable and together with the stitch cams, depending on its position, forms sinking surfaces of different sizes and/or forms.
With this sinking element it is possible to obtain an optimal stitch pattern during both double-surface R-R knitting and during single surface smooth knitting. The stitch cams can be provided for example with a small sinking surface, which is active alone when an R-R knitting must be produced. On the sinking element also a surface can be provided which during a corresponding adjustment of the sinking element expands the sinking surface of the needle sinker so that a wide sinking surface is produced, which is optimal for producing a single-surface smooth knitting.
The adjustment to different bonding types is also possible in the inventive flat knitting machine in a simple manner. An exchange of a stitch cams is no longer required. However, a corresponding control of the sinking elements must be provided. Depending on the adjustment of the sinking element, a small or a wide sinking surface can be adjusted. Further advantages are produced when the needle sinkers and/or the sinking element has positive guiding surface for the needle feet. Thereby an uncontrolled needle movement which provides non uniformities in the stitch pattern are excluded.
The sinking element can have also a guiding surface for the needle feet, which after sinking of a stitch activates a drive of the needle in a definite distance from the sinking surface. Thereby the tensioning which acts on the knitted thread can be reduced. The different knitting bindings must be realized with different knitting yarns. When the forces in the knitting threads during the knitting process become too high, they are torn. A knitted article with such thread torn parts (“splinters”) is a reject. Due to the guiding surface on the sinking element, it is however now possible, shortly after reaching the deepest sinking point, to drive the needles in a desired manner by a small distance and thereby to reduce the thread tension in the pulled-in stitch loop. During high knitting speeds a tearing of the knitting threads is prevented by these features.
The sinking element can also have a guiding surface for the needle foot, with which the pulling-in depth of predetermined needles relative to the pulling-in depth of the needle sinker-sinking surface is changeable. Thereby stitches can be formed, which have a size difference to corresponding stitches which are formed by the needle sinker-sinking surface. Therefore, a stepless adjustment of the stitch size difference by a stepless adjustment of the pulling-in depth of the predetermined needles can be performed.
For the adjustable arrangement of the sinking elements on a cam there are different possibilities. In a preferable embodiment of the present invention the sinking element is turnably arranged on the needle sinker.
It is especially advantageous when the sinking element is adjustable during the knitting process. The stitch form and size can be therefore adjusted without holding the machine during the knitting process. When the cams moreover operate in accordance with the pressing cam technique, it is also possible to definitely adjust the sinking surfaces for each individual stitch.
The novel features which are considered as characteristic for the present invention are set forth in particular in the appended claims. The invention itself, however, both as to its construction and its method of operation, together with additional objects and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings.
REFERENCES:
patent: 579199 (1897-03-01), Wakeman
patent: 2440496 (1948-04-01), Weinstein
patent: 4774818 (1988-10-01), Ploppa et al.
patent: 5367892 (1994-11-01), Shima et al.
patent: 5475990 (1995-12-01), Schmid et al.
patent: 5992183 (1999-11-01), Shima
patent: 448 358 (1968-03-01), None
Schmid Franz
Stoll Thomas
H. Stoll GmbH & Co.
Striker Michael J.
Worrell Danny
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