Guide bar arrangment for warp knitting machine having bending tranducers

A guide bar arrangement for a warp knitting machine has at least one guide bar, which is axially displaceable by means of a displacing arrangement and is carried, suitably on an axially rigid holding arrangement attached to a swinging shaft, through the intermediation of a compensating arrangement. The compensating arrangement and the displacement arrangement include bending transducers, which are attached at one end thereof on the holding arrangement (a lever 19 holding rails) and on the other end thereof on the guide bar and are bendably deformed under the influence of a direct current control signal. This leads to a simple construction of the guide bar arrangement with little frictional loss.

FIELD OF THE INVENTION 
The invention is directed to a guide bar arrangement for a warp knitting 
machine wherein the guide bar is axially displaceable by a displacement 
arrangement and is held by an axially non-displaceable holding means 
suitably attached to the swinging shaft via an intermediately placed 
compensating arrangement. 
BACKGROUND OF RELATED ART 
In a known guide bar arrangement of this type, DE GM 185 710 0, the 
displacement arrangement comprises a pusher rod controlled by a cam plate 
against which the guide bar is held by means of a return spring. The 
smoothing arrangement, which enables the displacement of the guide bar 
with respect to levers attached to the swinging beam, is provided by a 
plurality of guide bolts which are held in axial bearings provided in 
roller bearing boxes. 
In order to drive the warp knitting machine at greater speeds, the guiding 
by the axial bearings must be substantially free of play. This leads to a 
larger amount of friction and a corresponding consumption of energy, which 
is converted into heat and thus to an undesired expansion of the guide 
bar. The high frictional forces also considerably bias the transfer 
elements of the displacement arrangement and also cause friction. At high 
working speeds, larger acceleration and deceleration forces also come into 
play. 
An object of the present invention is to provide a guide bar arrangement of 
the foregoing type having a substantially simpler construction and only 
negligible frictional losses. 
SUMMARY OF THE PRESENT INVENTION 
In accordance with the illustrative embodiments demonstrating features and 
advantages of the present invention, there is provided, a guide bar 
arrangement for a warp knitting machine having a swinging shaft. This 
arrangement includes a guide bar and a displacing arrangement for axially 
displacing the guide bar. Also included is a holding means having an 
intermediating compensating arrangement for supporting the guide bar. The 
holding means is axially fixed and attached to the swinging shaft. The 
compensating arrangement and the displacement arrangement include a 
plurality of bending transducers, each having one end attached to the 
holding means and another end attached to the guide bar. The bending 
transducers are deflectable under the influence of an electrical control 
signal. 
An improved smoothing arrangement and displacing arrangement can thereby be 
formed with bending transducers which are attached at one end thereof in 
the holding means and the other end thereof carrying the guide bar and are 
deformed under the influence of a control signal. In such an arrangement, 
it is no longer necessary to utilize the various elements of the 
displacement arrangement (for example pattern cam disk, pattern chain, 
setting motor and the like). Also unnecessary are all of the axial 
bearings of the smoothing arrangement. Rather all of the functions of the 
displacement arrangement and the compensating arrangement may be taken 
over by the bending transducers. 
The number of required bending transducers is determined by the machine 
production level or the expected requirements of servicing. Even with two 
bending transducers, a parallelogram is formed together with the holding 
means and the guide bar in such a manner that even with deformation of the 
bending transducers, the guide bar is still held parallel to the holding 
means. 
The change in height of the guide bar during the conventionally occurring 
displacement arrangement is so small that for practical purposes, it can 
be ignored. In practice however, a larger number of bending transducers 
are utilized, on the one hand to give the guide bar a higher stability 
despite axial movement and on the other hand to provide the bending 
deformation with a sufficient displacing force. 
It should be noted that the displacing force is held to be substantially 
less than was utilized heretofore since it is unnecessary to utilize a 
return spring in order to achieve a force transferring contact between the 
displacing arrangement and the guide bar. Furthermore, it should be noted 
that the additional mass on the guide bar due to the bending transducers 
is substantially less than the additional mass thereto provided by the 
axial bearings so that a higher rate of working speed may be obtained. 
It is particularly advantageous if the holding means on the lever attached 
to the swinging shaft comprises a holding rail and that the bending 
transducers are distributed over the entire length of the guide bar. By 
utilizing a holding rail, the bending transducer groups may be located at 
a comparatively small distance from each other so that the holding points 
of the guide bar are comparatively close. This permits the guide bar to 
have a smaller cross-section and thus to be provided with a lower mass 
which again leads to a higher working speed. 
It is further advantageous to provide the bending transducers in mutually 
attached groups which are provided with a common header for fastening onto 
the holding means and a common footing for fastening onto the guide bar. 
In this manner, it is possible to insert and remove groups of bending 
transducers, which is very useful for assembly and repair. 
Suitably, the bending transducers are piezoelectric transducers which have 
an active layer of piezoelectric material in strips either on one side or 
on both sides. Such bending transducers may be readily activated by a 
control potential and react very readily to such control potentials. It is 
thus possible to operate with conventional high working speeds and even 
achieve yet higher working speeds. However, the invention may include the 
use of other bending transducers, for example, electromagnetic or 
magnetostrictive or otherwise activated transducers. 
It is preferred to provide the strip-shaped carrier with a protrusion at 
its foot end extending beyond the active layer. This non-activatable layer 
increases displacement of the guide bar so that the displacement path of 
several millimeters may be achieved. 
It is advantageous to make the strip carriers of a carbon fiber composite, 
that is, a polymer filled with carbon fibers. This yields a particularly 
light, but stable construction to the bending transducer. 
It is particularly advantageous if the provision of the control current 
causes the bending transducers to move from a neutral position either to 
the left or the right, as desired. Thus, if there is applied a positive 
control potential and another time a similar negative control potential to 
the bending transducer, there are provided three equidistant positions of 
the guide bar so that, for example, a tricot base fabric can be knitted. 
By utilization of different potentials, it is also possible to provide 
different displacement movements. 
In a preferred embodiment, the strip formed carriers are made out of an 
electrically isolating material and on both sides are provided with a 
coating comprising an inner electrode, an active layer and an outer 
electrode, wherein the inner electrode is connected to the power source 
and the outer electrode to ground. Such a bending transformer has the 
further advantage that it may be safely touched since the outermost 
electrodes are grounded. 
It is also advantageous to provide a displacement control arrangement, 
which provides the control current to the bending transducers in 
predetermined size as well as in accordance with the predetermined 
program. In this manner, the displacement arrangement can be so carried 
through that no excessive acceleration or deceleration occurs. Further 
details may be found in Applicants' copending application DE P 44 11 528.8 
(corresponding to U.S. Ser. No. 08/412,167) which is incorporated herein 
by reference. 
It is furthermore advantageous to provide stops to limit the displacement 
path of the guide bar. It is possible to achieve displacement targets very 
rapidly, however it is still advantageous to provide definite end points. 
Furthermore, these stops can be moved by a drive means such as a setting 
motor. It is thus possible to drive the guide with very different 
displacement steps. 
In a further embodiment of the invention, the guides themselves may be 
displaceable by piezoelectric deflecting transducers carried by the guide 
bars and individually influenceable by control potentials. In this manner, 
guide bar may be both displaceable by bending transducers and equally acts 
as a jacquard controlled guide bar because of deflecting transducers.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
FIG. 1 shows the working area (1) of a warp knitting machine having a 
needle bar (2) carrying needles together with the appropriate sliders on 
slider bar (3), a stitch comb bar (4) and a knock-over bar (5) over whose 
upper edge finished fabric (6) may be pulled. Two guide bars (7 & 8) with 
guides (9 & 10), respectively form the fabric ground. A guide bar (11) 
having jacquard control guides (12) provides the patterning. 
The several guide bars have interposed bending transducers (13, 14 and 15) 
that are held by a holding means, shown herein as holding rails (16, 17 
and 18) and swing lever (19). These latter are held fast on swinging shaft 
(20) and may be moved to and fro in the direction of arrow (21) wherein 
the-guides (9, 10 and 12) may be moved from the illustrated overlap 
situation into the underlap position and back again. 
Under the term "bending transducers," there are included in the first 
instance elements made out of a bendable material which, under the 
influence of an outside force, suitably electrical or mechanical is 
deformed through bending. For the presently required purpose, these 
elements are preferably in strip form. 
Referring to FIGS. 2 and 3, holding rail (18) stretches over the entire 
length of right-hand guide bar (8). Eight piezoelectric bending 
transducers (15) are put together in groups (22 and 22a), which have a 
header (23 and 23a) and a footing (24 and 24a), respectively. The 
piezoelectric bending transducers (15) are connected with the header (23) 
and the footing (24). Screws (25) which grasp through holes (26) serve to 
attach the header (23) to the holding rail (18). Screws (27) grip through 
holes (28) and serve to affix the footing (24) to the guide bar (8). The 
latter generally carry leads (29), which are attached by means of screws 
(30) and themselves carry a plurality of guides (10). 
Two signal leads (32 and 33) are attached to control arrangement (31) over 
which the electrical potential of a control signal may be led to the 
depending transducers (15) as is further illustrated in FIGS. 5 and 6. The 
holding rail (18) is grounded at (34). By providing the control potential, 
the lower ends of the bending transducers (15) are displaced in one or the 
other direction so that the guide bar (8) can provide a displacement (X1). 
Stops (35 and 36) serve to limit the extent of travel of the displacement 
movement and thus provide an exact setting for guides (10) during their 
swing through the needle gaps between the needles. 
In FIG. 3, a composite displacement (X) is illustrated. The stops (35 and 
36) can be further displaced by the setting motors (drive means 37 and 38) 
receiving signals through leads (39 and 40) connected to the control 
arrangement (31) . 
FIGS. 4 and 5 show the left-hand guide bar arrangement of FIG. 1 with guide 
bar (11) and holding rail (16) . Furthermore, groups (41) of bending 
transducers (13) are connected at their upper end with header (42) and at 
their lower end with footing (43) which, similarly to what is shown in 
FIGS. 2 and 3, are connected with holding rail (16) by means of screws, 
for example screws (44). 
The bending transducer (13) comprises, as shown in FIG. 6 a strip-formed 
carrier (45) of electrically insulating material, for example, reinforced 
glass fibers. On one side of carrier (45) there is a layer comprising: 
inner electrode (46), the piezoelectrically activated layer (47), and 
outer electrode (48). On the other side of carrier (45) is a layer 
comprising: inner electrode (49), piezoelectrically active layer (50), and 
outer electrode (51). 
The two inner electrodes (46 and 49) are connected with signal leads (32 
and 43). The two outer electrodes (48 and 51) are grounded via the 
potential of the mass of the machine, whereby the header (42) and the 
holding rail (16) and are grounded. For this purpose the header (42) is 
provided with comb-like grooves (52) in which the upper end of the bending 
transducers (13) can be slid and there clamped or affixed by other means. 
The strip-formed carrier (45) possesses a protrusion (53) extending beyond 
the active layers (47) and (50) and whose lower end is set in a slit in 
footing (43). 
Commencing at a neutral position of bending transducer (13), upon the 
application of a control potential to the inner electrode (46), the 
footing (43) moves to the left and by the provision of a control potential 
to the right inner electrode (49) it moves to the right. The displacement 
distance is substantially proportional to the loading on the bending 
transducer and thus is proportional to the applied DC voltage potential. 
By successive applications of equal potentials, displacements of equal 
size will occur, which without any difficulty may be set to be equal to 
one or a plurality of the spacings between the needles. In this manner, it 
is possible to control the displacement in a pattern conforming manner. 
Furthermore, as is shown in FIG. 7, in the course of a work cycle A, the 
control potential in volts DC follows a curve (k) in which: segment (a) 
corresponds to the overlap displacement; segment (b) follows the 
swing-through into the underlap position; segment (c) shows the underlap 
displacement itself; and segment (d) shows the swing back of the guide bar 
(11) into the overlap position. The individual segments may run in 
straight lines, however in between them advantageously, there are 
transition steps. In this way at the beginning one seeks a modification of 
the acceleration of guide bar (11) and modification of the deceleration at 
the end of the cycle. There are here no excessive counter forces so that 
there is provided a trouble free mode of proceeding. 
The guides (12) are attached to carrier strips (54) on piezoelectric 
deflecting transducers (55), which in turn are affixed to header (56). 
This is attached to guide bar (11) by means of screws (57). Electrical 
leads (58) are connected to control arrangement (31). In this way guides 
(12) may be displaced in the manner of a jacquard control. With respect to 
further specific questions of such jacquard control with piezoelectric 
bending transducers, reference is made to Applicant's prior German patent 
applications, namely P 42 26 899 (U.S. Ser. No. 08/1 04,369); P 43 16 396, 
P 44 14 876 (U.S. Ser. No. 08/426,887), and P 44 18 714 (U.S. Ser. No. 
08/412,167), whose disclosure is incorporated herein by reference. The 
construction of the piezoelectric bending transducers described in the 
foregoing applications may be similarly utilized for bending transducers 
(13 through 15) of the present application. 
This structure may also apply as well to the provision of a second bending 
transducer in the region of the extension (43 of FIG. 1) which can bend in 
a direction opposite to that of the first bending transducer. By means of 
the second bending transducer, the lower end of the strip-formed carrier 
is displaced parallel to itself during the bending formation. The loading 
of the carrier on the attachment point on the guide bar side is therefore 
minimal. 
FIG. 8 illustrates the upper end of the bending transducer (59). A 
strip-formed carrier (60) is made of a synthetic material strengthened 
with carbon fibers, which makes it electrically conductive. On one side, 
it carries a layer of piezoelectrically active material (61) having an 
outer electrode (62) and on the other side there is coated a 
piezoelectrically active layer (63) having an outer electrode (64). The 
outer electrode (62) is connected with signal line (32) and the outer 
electrode (64) with signal line (33). The electrically conductive carrier 
(60) is grounded at point (34). Such a bending transducer can be very 
light in weight, and still be made with very high stability. 
It is to be appreciated that various modifications may be implemented with 
respect to the above described preferred embodiments. For example, in many 
cases it is sufficient if the holding means comprises the swinging lever 
(19). The holding rails (16, 17 and 18) may no longer be required. 
Obviously, many other modifications and variations of the present invention 
are possible in light of the above teachings. It is therefore to be 
understood that within the scope of the appended claims, the invention may 
be practiced otherwise than as specifically described.