Warp knitting machine with pattern

A warp knitting machine with bearded needles (5) and a pattern press comprises a driven press bar (10) having individual press elements thereon. These are so controllable that during the working stroke (47) of the press bar (10) at choice there is provided a press contact onto the hooks (19) of the corresponding bearded needles (5) or not. Every pressing element (46) is provided with a piezoelectric bending transducer ((42) attached at one end whose free end (45) in the direction of the needle bed may either move from a first position during the working stroke 47 into a press contact and in a second position in which the press element 46 or a power transmitting element located forwardly thereof in the direction of the needle bed may be displaced. In this manner, it is possible to provide a safely constructed pattern press suited for high velocity operation.

FIELD OF THE INVENTION
 The invention is directed to a warp knitting machine with bearded needles
 and a pattern press comprising a driven press bar and individually
 steerable press elements thereon which, as desired during the working
 stroke of the press bar may either exercises press contact with the hooks
 of the appropriate bearded needles or not.
 In the known warp knitting machines of this type (DE-PS 445 428) the press
 contact is achieved therein that a press bar carried by a lever is moved
 towards the bearded needles wherein a pin shaped press element carried by
 the press bar acts upon the hooks of the bearded needles. With the
 assistance of harness cords the pressing elements parallel to the needle
 shafts can be lifted so far that the bearded needles can freely move away.
 In DE 44 18 714 (U.S. Pat. No. 5,533,366) there is provided a warp knitting
 machine having guide bars wherein the guides are provided with the free
 ends of a plurality of piezoelectric bending transducers, wherein one end
 of the bending transducers is affixed to the guide bar. By electrical
 control of the bending transducers, the guides are caused to take one of
 two positions determined by stops. This allows the patterning of the
 goods.
 The task of the invention is to improve the patterning press of a warp
 knitting machine of the prior art.
 The invention solves this problem wherein each pressing element is provided
 to a piezoelectric bending transducer attached to one end thereof, the
 free end of said transducers, in the direction of the needle bed is
 displaceable from a first position during the working stroke so that press
 contact occurs, and in a second position in the pressing element or a
 force transmitting element provided in series therewith in the direction
 of the needle bed, is deviated.
 In the first position the working stroke of the pressing element is carried
 over to the hooks of the bearded needles, in the second position on the
 other hand because of the displacement, the press element for example, a
 force transmitting element in series therewith to and after provided force
 transmitting element moves sidewardly past the bearded needle. The return
 path of the free end of the bending transducer is exceedingly short. This
 allows for a high working speed since a piezoelectric bending transducer
 follows steering commands exceedingly rapidly. The complexity of
 construction is low. Bending transducers can be provided next to each
 other with very small separation so that it is possible to provide each
 bearded needles with its own bending transducer.
 A particularly simple construction results from the piezoelectric bending
 transducers being attached to the press bar and carrying the pressing
 element at their free end.
 A preferred alternate embodiment exists therein that the piezoelectric
 bending transducer is affixed to the press bar and its free end is coupled
 with a pressing element in the form of a lever wherein, the lever is
 carried by the press bar. By use of the lever the bending transducer is
 not subjected to the pressing force. Thus, it may be constructed in a
 weaker and thus narrower manner.
 It is also desirable that the press element is in the form of a guided
 slider. The piezoelectric bending transducer is attached to the press bar
 and the free end thereof in the first position interacts with the slider
 and in the second position is displaced relative to the slider. The use of
 such slider permits the hooks of the bearded needles to be contacted very
 accurately.
 In a similarly desirable alternative it is provided that the press element
 as a guided slider, the piezoelectric bending transducer is attached to a
 carrier affixed to the machine and its free end is provided with a
 protrusion which grips into a longitudinal groove of a lever born by the
 press bar and this, in the first position, interacts with the slider and
 in the second position is displaced with respect to the slider. Also in
 this modification the bending transducers are not subjected to the force
 of the pressing force. Since they are attached to a carrier rigidly
 attached to the machine, the electrical conduit lines do not create any
 problems. Since they are attached to a carrier attached to the machine,
 the electrical conduit lines do not exercise any bias during the working
 stroke. Preferably the pressing element is a sliding element guided in a
 longitudinal slot. These slots allow very accurate interaction with the
 bearded needles.
 It is an equally desirable alternative to provide that the slider is
 swingable about an axis parallel about the needle bed.
 It is also useful to provide the sliders with return stop onto which cams
 attached to the press bar can grip. These unidirectional acting return
 stops serve their function without influencing the switching action of the
 bending transducer.
 It is also advantageous that the slider is covered with a friction
 resistant sliding coating. This supports the rapid to and fro movement of
 the slider.
 It is advantageous to provide that the guides for several sliders are
 collected together in a single guide segment. Thus, repairs can be readily
 carried out by removal and replacement of such segments.
 It is also desirable to provide a plurality of parallel piezoelectric
 bending transducers in a transducer segment which carries stops
 determining the first and second position of the free ends. These stops
 enable exceedingly accurate positioning.
 It is further desirable that the pressing elements and/or the bending
 transducers are provided with polymeric caps. This reduces noise and
 abrasion.
 It is further desirable to provide these polymeric caps with a side wall
 protruding beyond the front face. This side wall serves as a secure
 separation between neighboring pressing elements.

DESCRIPTION OF THE PREFERRED EMBODIMENTS
 The warp knitting machine in accordance with FIG. 1 comprises a machine
 frame 1 and a main shaft 2 which drives a needle bed 4 with bearded
 needles 2 via a lever 3, a sinker bar 7 with closing knockover sinkers 8
 via lever 6, a press bar 10 with a piezoelectric bending transducer
 control arrangement 11 via lever 9, and guide bars 13 and 14 with guides
 15 via level 12. A sensor 16 generates a rotational angle signal
 corresponding to the rotational angle which is led to the pattern provider
 17. This provides signals the control instructions corresponding to the
 desired pattern via conduit 18 to the bending transducers control
 arrangement 11. In consequence thereof a selection of press elements 20
 are pressed against the hooks 12 of needles 5, as will be described in
 detail hereinbelow.
 In the bending transducer arrangement 21 as shown in FIG. 2, strip formed
 piezoelectric bending transducers 22 are affixed at one end 23 and
 connected with press bar 10 which moves in the direction of working stroke
 24. The free end 25 of bending transducer 22 is rigidly connected with a
 press element 26. When the press element 26 find itself in the first
 position during the working stroke 24, it impinges upon hook 19 of needle
 5 and closes the hook space so that subsequent thereto, with the
 assistance of sinker 8, a stitch is knocked over. When free end 25 is
 moved slightly into the direction of the needle bed, that is to say,
 perpendicular to the plane of the drawing, the press element 26 moves
 between neighboring needles 5 without touching these. The transducers 22
 are affixed together into segments 27 which also carry stops 28, which
 clearly define the first and the second positions of free end 25.
 In the embodiment shown in FIG. 3 the transducer control arrangement 31
 comprises a transducer 32 which again is affixed at end 33 and connected
 with a press bar 10. The free end 35 of the deflector 32 is connected with
 a press element 36 in the form of a lever. This lever, via bearing 37,
 which is displaced towards spring end 33 is carried by press bar 10. In
 this arrangement, transducers 32 do not transfer any pressure forces
 during the working stroke 34. Furthermore, the path of the free end 35 is
 increased by the left translation at the free end. Thus, one merely
 requires smaller and weaker deflectors 32. Also here, in the first
 position of the transducer 32, press element 36 presses on the hook of
 needle 5, whereas press element 36 in the second position of the free end
 of the transducer 32 moves past the needle 5.
 In the embodiment shown in FIG. 4 the piezoelectric transducer control
 arrangement 51 comprises a transducer 42 which, at its end 43 is rigidly
 attached to press bar 10. Thus, the free end 44 can take up two positions
 which are determined by the stops 45. In the first position a press
 element 46 in the form of a slider element is pushed against the hook 19
 of needle 5. In the second position the free end 44 slips sideways past
 the press element 46 when the press bar 10 performs the working stroke 47.
 The press elements 46 are located in longitudinal slots of a guide segment
 48 which is held in a carrier 49 rigidly attached to the machine. On the
 press bar 10 there is provided a cam 50 constructed as a ledge which
 operates with a return stop 51 on each slider 46 in order to bring this
 back on the starting position on the backward stroke.
 In the embodiment of FIG. 5 the bending transducer control arrangement 61
 at its end 62 is clamped to a carrier 63 rigidly attached to the machine.
 The protrusion 65 at free end 64 grabs into a longitudinal slot 66 of a
 lever 67 which is rotatable about a pivot 68. In the first position of the
 free end 64 of the 62, during the working stroke 70 the left face 69 of
 lever 67, meets the pressing element 71, constructed as a slider, that is
 again led into the guide slot of guide element 72. On the other hand, in
 the second position the lever 66 bypasses the press element 71.
 Transducer control arrangement 81 of FIG. 6 is different from that of FIG.
 2 in that a lever is utilized as press element 82 which is swingable about
 an axis 83 affixed in the machine which runs parallel to the needle bed,
 that is to say, perpendicular to the plane of the drawing.
 FIGS. 7 and 8 show an arrangement similar to FIG. 4. A plurality of
 piezoelectric bending transducers 92 are collected and held together in a
 bending transducer element 93 which may be taken from and affixed to press
 bar 1 as a complete unit. For a plurality of press elements 95 there are
 always provided guide segments 96 which similarly are provided as a single
 unit.
 As is shown in FIG. 8, the free ends 97 of the bending transducer 92 can
 move between two stops 98 and 99, so that they will take either position
 "a" or position "b". Each bending transducer 92 is provided with a
 polymeric cap 100, which comprises a side wall 102 protruding beyond front
 face 101. This side wall 102 in position a enables a press element 95 to
 move with it. The side wall 102 ensures that there is always sufficient
 separation between neighboring press elements.
 FIGS. 9 and 10 again show the working area of bearded needle 5. Press
 element 110 is constructed as a sliding element which is led in slot 110
 of guide segment 112. This guide segment is affixed to an item rigidly
 affixed to the machine. The press element 110 has a polymeric cap 113 at
 its forward end, which protects the needle material and also reduces
 machine noise. FIG. 10 shows the first, third and fifth press elements 110
 having reached the press point and performing the pressing contact. On the
 other hand, the second and fourth press elements 110 remain in their at
 rest position and do not perform a pressing contact.
 FIGS. 4 to 6 show that the construction parts necessary for the guidance of
 slider pieces in particular, carrier 49, may be readily located between
 needle bar 4 and press bar 10.
 In the embodiments of FIGS. 2 and 3 the press elements are minimally
 displaced to the sides so that they move past the bearded needle 5.
 On the other hand, in the embodiments of FIGS. 4 through 6 there a force
 transfer change results between the press bar and the press elements
 comprising a plurality of force transmission elements. Under these
 circumstances the pressing element is not displaced sidewards, but by
 means of one of the previously mentioned force transfer elements for
 example, bending transducers 42 or lever 67, are prevented from press
 contact
 position, in which said free end is positioned so as not to contact said
 corresponding one of said pressing elements.