Textiles: knitting – Feeding – Traversing guides – straight machine
Reexamination Certificate
1999-01-13
2001-01-09
Worrell, Danny (Department: 3741)
Textiles: knitting
Feeding
Traversing guides, straight machine
C066S12500A, C066S146000
Reexamination Certificate
active
06170301
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a method of producing a knitted article on a flat knitting machine, and to a flat knitting machine for producing a knitted article.
There are a plurality of knitted articled in which threads of different elasticity are processed together. For example in supporting or compression hosiery the wearing comfort is obtained by a textile base thread of low elasticity and the definite supporting and compression force is provided by the clamping force of an elastic thread. The elastic threads can be composed of different materials, such as elastomers or rubber mixtures. They can be spun also from other threads. Depending on the material and the construction of the threads their elasticity differs when the pulling forces act on them by the thread guide of the knitting machine. For a uniform knitting image it is necessary, during supply of threads with different elasticity for the loop formation to the needles of a knitting machine to monitor that the threads of higher elasticity are inserted with lower tension in the needle hooks and distributed uniformly over the total knitted article width. Moreover, it is necessary to monitor that the both threads of different elasticity form a stitch of the same shape and size.
For round knitting machines, an arrangement has been developed which supplies the threads of higher elasticity to the thread guide with stress which is specific for it and the knitted article to be produced. The device has two parallel shafts which are driven in the same direction and on which the coil with the elastic thread lies with its periphery. The shafts are coupled with the drive of the knitting machine through a toothed belt. The rotary speed and thereby the peripheral speed of the shafts have a fixed ratio to the rotary speed of the knitting machine. In the event of high knitting speed, many threads are wound from the coil, and in the event of the low knitting speed correspondingly lower number of threads is wound from the coil. In the flat knitting machines this device however can not be used since there in one knitting row, stitches of different sizes can be formed and also the width of the individual stitch row can be different. A supply of thread with higher elasticity alone in dependence from the knitting speed is here not possible.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to provide a method of producing a knitted article with a uniform supply of two threads having different elasticities to a needle, which can be used with a flat knitting machine and provides a completely uniform stitch image.
In keeping with these objects and with others which will become apparent hereinafter, one feature of present invention resides, briefly stated in a method of the above mentioned general type in for which each stitch to be formed the length of the thread with a higher elasticity supplied to a needle is calculated from the length of the thread of lower elasticity to be supplied and the data about the material properties of the thread of the higher elasticity, and a feeding device for the thread of the higher elasticity is controlled in correspondence with the calculated thread length to be supplied.
In accordance with this process for each stitch in particular the length of the elastic thread to be supplied is determined in dependence on its material properties as well as the supplied length of the thread of the lower elasticity. Thereby always an optimal thread supply for all pattern types and thread types is provided.
In accordance with a preferable embodiment of the method, an average factor is calculated from the data about the material property of the thread of the higher elasticity, it is multiplied with the length of the thread of the lower elasticity to obtain the length of the thread of the higher elasticity to be supplied.
The thread with the higher elasticity must be inserted with a substantially lower tension into the needle hook than the thread with the lower elasticity. This tension is provided in that the lower thread quantity corresponding to the average factor, than the thread of the lower elasticity, is supplied for the stitch formation. Moreover, the knitting direction can be taken into consideration, in that more threads of higher elasticity is supplied when the knitting direction is back from the feeding device for the thread of the higher elasticity and forward when the knitting direction is to the feeding device. In this way an optimal tension of the thread with the higher elasticity is guaranteed independently from the knitting direction.
The information required for calculation of the length of the thread of the higher elasticity to be supplied via the supplied length of the thread of the lower elasticity can be determined for example by a measuring device. The supplied length of the thread of the lower elasticity can be however also calculated from the data supplied by a machine control unit related to the corresponding stitch size of the thread of the lower elasticity, the stitch sequence, and the number of the stitches in the corresponding stitch row. A measuring device can be dispensed with. The both threads of different elasticities can be supplied with a common thread guide or also by separate thread guides without substantially changing the method.
The present invention also deals with a flat knitting machine which has at least one needle bed for performing the inventive method, and which has a coil for the thread of the lower elasticity, a feeding device of the thread of the higher elasticity, at least one thread guide for the both threads of different elasticities, a machine control unit and a computing and control unit for determination of the length of the thread of the higher elasticity to be supplied and for controlling the feeding device for the thread of the higher elasticity.
The feeding device, similarly to the feeding devices of the elastic threads in round knitting machines, can have two parallel feeding rollers of identical diameters which are driven in the same direction, and on which a coil with the thread of the higher elasticity lies with its periphery.
The feeding device can be provided with an electric motor which is coupled with the computing and control unit, whereby the peripheral speeds of the feeding rollers can be regulated in correspondence with the calculated length of the thread of the higher elasticity to be supplied.
Between the coil for the thread of the lower elasticity and the thread guide, in a known manner a thread tensioner can be arranged for a tension equalization in the event of abrupt speed changes of the thread guide. Moreover, a thread breakage sensor can be provided for the thread of the higher elasticity.
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.
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patent: 5353610 (1994-10-01), Barea
patent: 5931023 (1999-08-01), Branch et al.
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patent: 40 32 402 A1 (1992-04-01), None
Schmid Franz
Stoll Thomas
H. Stoll GmbH & Co.
Striker Michael J.
Worrell Danny
LandOfFree
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