Abstract:
A flat knitting machine has at least one needle bed, a carriage which slides along the needle bed which has at least one cam with needle section means and stitch cams, a sinking element which cooperates with the stitch cams and is arranged movably on the stitch cams, the sinking element being controllable independently from the stitch cams and together with the stitch cams forms sinking surfaces of different size and/or form depending on its position.

Description:
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. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a view schematically showing a knitting cam of an inventive flat knitting machine at a side facing a needle bed; 
     FIG. 2 is a detailed view of a stitch cam with a sinking element of the knitting cam of FIG. 1, in a first adjustment position of the sinking element; 
     FIG. 3 is a view substantially corresponding to the view of FIG. 2, in a second adjustment position of the sinking element; 
     FIG. 4 is a view showing a section taken along the line IV—IV through an arrangement of FIG. 3; 
     FIG. 5 is a view substantially corresponding to the view of FIG.  2  and showing a stitch cam with a sinking element of a second embodiment; 
     FIG. 6 is a view substantially corresponding to the view of FIG.  2  and showing a stitch cam with a sinking element in accordance with a third embodiment; 
     FIG. 7 is a view substantially corresponding to the view of FIG.  2  and showing a stitch cams and a sinking element for stepless influence of the stitch size; 
     FIG. 8 is a view showing a section taken along the line VIII—VIII through the arrangement of FIG.  7 . 
    
    
     DESCRIPTION OF PREFERRED EMBODIMENTS 
     A knitting cam  100  shown in FIG. 1 has a needle driving out part  110  which cooperates with a limiting part  120 . Moreover, a forwardly running needle sinker  130  and a rearwardly running needle sinker  140  are provided on the knitting cam  100 , as considered in a movement direction identified with the arrow  150 . The needle sinker  130  is therefore outside operation. Moreover, the knitting cam  100  has two sinking elements  160  and  170 , which cooperate with the needle sinkers  130 ,  140  as will be described herein below. 
     The arrangement  1  shown in FIG. 2 corresponds to the needle sinker  140  and the sinking element  170  of FIG.  1 . The needle sinker is here identified with reference numeral  2  and the sinking element is identified with reference numeral  3 . The sinking element  3  is supported on the needle sinker turnably around a turning point  40 . By acting in direction of the arrow  11 , the sinking element  3  is turned to its inner end position. A sinking surface  8  which is available on it is thereby set outside operation. The feet  10  of the not shown needles which participate in the knitting process slide along a plane  5  of the needle sinker  2 , until they reach a sinking position corresponding to the proper stitch size under a small sinking surface on the needle sinker  2 . In this sinking position the needle feet  10  are positively guided by a surface  7  on the needle sinker  2 , whereby a high uniformity of the stitch size is achieved. The smaller sinking surface  6  provides an optimal stitch pattern for R-R knitting. 
     FIG. 3 shows the arrangement  1  of FIG. 2, when the sinking element  3  is turned by acting in direction of the arrow  12  to its outer end position. Now the sinking surface  8  closes on the sinking surface  6  of the stitch cam  2  and thereby expands it. Due to the expanded surface  6  and  8 , now several needle feet  10  can be simultaneously held in the deepest sinking position. Thereby an optimal stitch pattern for a single-surface smooth knitting is obtained. 
     As can be seen in the section shown in FIG. 4, the sinking surfaces  8  of the stitch cam  2  and the sinking surfaces  8  of the sinking element  3  are located in different planes. This makes possible, in cooperation with not shown needle selection device and also not shown knitting cam with pressing cam technique, to achieve that each individual knitting needle can be preset so that it must be sinking over the small sinking surface  6  or over the wide sinking surface  6  plus  8 . Needle feet  10  which abut with half foot height against the stitch cam  2  are sinking on the small surface  6 , and the needle feet  10  which abut against the whole foot height on the stitch cam are sinking on the surface  6  plus  8 . In this manner it is possible in the knittings in which within one knitting row in exchange of a single-surface binding type to a double-surface binding type occurs, to form each stitch in the optimal form. 
     The arrangement  60  shown in FIG. 5 corresponds to the arrangement  1  of FIGS. 2 and 3, but with the additional possibilities that the needles after reaching the sinking position can perform a definite unloading movement. The arrangement has again a stitch cam  2  and a sinking element  30  which is turnable to its inner end position around the point  40  and assumes the position shown in FIG.  2 . The sinking element  30  has however an additional guiding surface  9  which presses the needle feet  10  after sinking against the small sinking surface  6  of the stitch cam  2  again a little upwardly and thereby somewhat drives out the needles, whereby the tension in the knitting threads is reduced. A positive guiding surface  15  is provided on the stitch cam  2  to bring the needles to their immovable position. In cooperation with the not shown needle selecting device and also not shown cam, with pressing cam technique for each individual knitting needle it can be determined whether they must perform the unloading movement or not. The needle feet  10  which about only with half foot height against the stitch cam perform no unloading movement, while the needle feet which abut with the whole foot height against the stitch cam are engaged by the curved surface  9  and thereby perform the unloading movement. 
     When with this structural shape of the sinking element  30  it is turned to its outer end position (not shown), the selected needles can be sinking either on the small sinking surface  6  or on the wide sinking surface  6  plus  8 . 
     The arrangement  50  shown in FIGS. 6 and 7 makes possible the formation of stitches with another stitch size than the stitches formed with the sinking surface  6  of the needle sinkers  2 . The arrangement has also a stitch cam  2  with a small sinking surface  6 , as well as a positive guiding surface  7 . The associated sinking element  31  is again supported turnably about a rotary point  41 , and in FIG. 6 is shown in its inner end position by loading in direction of the arrow  11 ″. The needle feet which only with a half foot height against the stitch cam  2  are sinking against the small surface  6 . The sinking surfaces  6  and the surface  7  form a positive guide. The feet which abut against the whole foot height against the needle stitch cam  2  are sinking on the wide sinking surface  6  plus  8 . The positive guidance is formed by the surfaces  7  as well as a further surface  14  on the sinking element  31 . 
     FIG. 7 shows the sinking element  31  which is turned under the action in direction of the arrow  12 ″ to its outer end position. The feet of the needles which form a stitch side corresponding to the needle sinking position are located with the half foot height against the stitch cam  2  and are sinking over the surface  6 . The surfaces  6  and  7  form a positive guide for these needles. 
     The feet of the needles which must form a greater stitch than that which corresponds to the needle sinking position, abut with the whole foot height against the stitch cam  2 . Their path for sinking extends over the planes  5  and  6  formed by the stitch cam  2 , to the plane  13  formed on the sinking element  31 , and then to the surface  81 . This surface  81  is the sinking surface for the greater stitches and forms a positive guide with the guide stitch limiting surface  14  which can be formed on the sinking element  31 . 
     The sinking element  31  can be turned from its inner turning position shown in FIG. 6 to its outer position shown in FIG.  7 . This makes possible a stepless increase of the stitches which are formed on the sinking surface  81 , when compared with those which are formed on the sinking surface  6 . The adjustment of the sinking element  31  can be performed during the knitting process, so that it is possible to produce individual stitches of the stitch row in different sizes. 
     It will be understood that each of the elements described above, or two or more together, may also find a useful application in other types of constructions differing from the types described above. 
     While the invention has been illustrated and described as embodied in flat knitting machine, it is not intended to be limited to the details shown, since various modifications and structural changes may be made without departing in any way from the spirit of the present invention. 
     Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can, by applying current knowledge, readily adapt it for various applications without omitting features that, from the standpoint of prior art, fairly constitute essential characteristics of the generic or specific aspects of this invention. 
     What is claimed as new and desired to be protected by Letters Patent is set forth in the appended claims.