Sewing machine

A sewing system is proposed, which has a sewing head with thread tightener, a presser foot, a lower thread roll with a shuttle for guiding the lower thread and transport or transfer means for the further transporting of the workpiece to be processed. Separate drives are associated with these individual elements and these drives are synchronously controlled by a control device.

The present invention refers to a sewing device in accordance with the 
preamble to claim 1. 
A sewing device of this type is already known from Federal Republic of 
Germany OS. No. 20 18 338. In that sewing device, the upper part of the 
needle drive unit is physically separated from the lower part with the 
bobbin or loop drive unit; no mechanical connecting members are present 
between upper part and lower part and the passage space for the sewing 
material is thus increased. In order to coordinate and synchronize the 
operation of the two drive units of the upper and lower parts of the 
sewing device, a plurality of electric control or regulating means are 
provided. With each drive unit of the upper and lower part there are, in 
their turn, associated a plurality of synchronized electric motor drives 
which displace the two drive units of the upper and lower part in 
synchronism along the X and Y axes, synchronized electric motor drives 
being, in addition, provided to turn the drive units of upper and lower 
parts in synchronism around the Z axis of the needle. In this connection 
the electric motor drives are, on the one hand, synchronized pairs of X 
and Y axis stepping-motor drives and, on the other hand, synchronized 
circumferential stepping motors with gear transmissions. The large number 
of electric drives required, as well as the expensive electric control or 
regulating devices resulting therefrom constitute a disadvantage. 
From Federal Republic of Germany patent No. 10 11 265 there is also known a 
sewing device with electromagnetic drive in which the individual movements 
are effected by decentral electromagnets. The electromagnet for the needle 
drive is fed via a sawtooth generator and an upward and downward movement 
of the needle bar is produced via the armature. A corresponding 
electromagnetic drive is provided in the lower part of the sewing device 
for the movement necessary for zigzag sewing. These electromagnetic drives 
are, however, still not capable of assuring sufficient synchronism for 
oscillating movements within the frequency range necessary for a sewing 
device operating with high operating speed, since disturbing variables, 
such as residual magnetism, impair the precision. Such a sewing device, in 
particular, cannot satisfy the conditions of an industrial sewing device. 
In the sewing device known from Federal Republic of Germany OS No. 29 18 
460 the individual gear units are developed as modules which are connected 
in force- and/or form-locked manner With each other Via a central drive 
unit. This is merely a modified structural design of the traditional 
sewing device with only a single central drive, one particular advantage 
of the gear modules residing in the rapid convertibility. The structural 
size of this sewing device remains, however, in the same order of 
magnitude as previous sewing devices, due to the use of shafts, cams, 
drive belts and the like. 
Similar disadvantages are present in the sewing device according to Federal 
Republic of Germany patent No. 29 03 031 which also has only a single 
drive unit which, via shafts, drive belts and the like, jointly drives the 
individual elements of the upper part and the lower part of the sewing 
device. 
In all the above-described sewing devices known from the prior art, 
electric drives having the disadvantages indicated in each case are thus 
exclusively employed. In addition, sewing devices operated by compressed 
air are known from Federal Republic of Germany OS No. 30 18 892 and from 
U.S. Pat. No. 3,812,801. The sewing device for medical operations in 
accordance with Federal Republic of Germany 0S No. 30 18 892 is not a 
sewing device in the true sense, since only one needle motion mechanism is 
formed via pneumatic pistons. Further elements of a traditional sewing 
device are not present. The sewing device of U.S. Pat. No. 3,812,801 has a 
traditional electromechanical drive for the movement of the needle. From 
this, the zigzag movement of the swingable upper part of the sewing device 
is derived via a pneumatic attachment. 
The sewing devices known from the prior art also have the substantial 
disadvantage that, with respect to their force transmission range the 
individual elements cannot be adapted to the type of material, the number 
of layers of material, the methods of manufacture selected or the like and 
changed in operating condition. 
The object of the present invention is to optimize the degree of freedom of 
the individual elements in a sewing device of the above-mentioned type, 
particularly for manufacture in the garment industry, in order to be able 
to adapt, and change in operating condition, the force transmission ranges 
of the individual elements independently of each other to the type of 
material, the number of layers of material, the manufacturing method 
selected and the like and furthermore to keep the weight and volume of the 
drives as small as possible. 
This object is achieved in a sewing device according to the preamble to 
claim 1 by means of the characteristic features set forth in that claim. 
With the sewing device of the invention, the drives of the individual 
elements can be controlled independently of each other within their force 
transmission ranges so that each individual element of the sewing device 
can be adapted and changed in operating condition to the type of material 
to be worked, the number of layers of material, the manufacturing methods 
selected, for instance the stitch geometry, and the like. For this 
purpose, each moving element of the sewing device has a separate hydraulic 
drive specifically tailored for said element, whereby a plurality of 
independent movements of the individual elements with respect to each 
other is possible. The courses of the movements of the individual elements 
are synchronously controlled and adapted to each other by means of the 
hydraulic pulse generator as control unit. Thus a central control of a 
plurality of sewing devices developed in accordance with the invention is 
also possible. 
In view of the separate drives for each individual element of the sewing 
device, the individual elements such as sewing head, underthread roller, 
looper, transport means and the like can be positioned flexibly, 
independently of the other elements. Thus, for instance, a change in 
direction of a seam is possible without changing the position of the 
material to be worked. Thus three-dimensional sewing articles can be 
produced. By the arrangement of the individual elements and their separate 
drives a rapid change of the elements is possible, so that the sewing 
device can be converted rapidly to other manufacturing methods and a rapid 
change of different stitch geometries is possible. 
Every sewing workplace can be optimally equipped, in accordance with the 
specific sewing task, with the sewing device of the invention since there 
is no impairment as a result of elements of the sewing device which are 
not required for the specific sewing work process. 
It is particularly advantageous that the individual elements be driven 
directly without mechanical deflection of the direction of movement. Since 
each individual element has its own individual drive, precise 
adjustability of the required forces, for instance for different types of 
material, is possible. Since disturbing influences of moments of rotation 
are excluded, the operating output of the sewing device is rapidly 
reached, it being possible to reach, from the standpoint of the drive, 
large speed ranges, for instance numbers of strokes of the needle of 
0.6.multidot.10.sup.4 /min. The individual drives can be adapted by 
construction to the different elements so that no unnecessary energy is 
consumed. Since flexible connecting lines can be used for the supplying of 
the individual drives (see claim 2), the individual elements have maximum 
freedom of positioning. Since mechanical parts are substantially 
superfluous, the sewing device is extremely quiet and vibrationless. 
The sewing device of the invention can be provided with an intelligent 
control system whereby, for instance, the replacement of the needle and of 
the upperthread roller or the underthread roller can be controlled 
automatically independently of the material being worked or as a function 
of the desired type of stitch. By the use of the pulse hydraulics which 
operates in the frequency range of up to 50 kHz, it is possible, by 
suitable structural development, to produce weld connections by 
ultrasonics as well as cutouts such as buttonholes.

ln FIG. 1, the movements of the individual elements of the sewing device 
are shown by directional arrows which are arranged above and below the 
work plane 1 of the sewing device. The stroke movement 2 of the needle 10 
takes place in the direction of the y-axis perpendicular to the work plane 
1. The deflection movement 3 of the needle 10 transverse to the direction 
of sewing in accordance with the z-axis takes place parallel to the work 
plane 1 in the direction of the x-axis. The tensioning movement 4 for the 
upper thread 40 takes place perpendicular to the work plane 1. The 
presser-foot movements 5V and 5H take place perpendicular to the work 
plane 1 in the direction of the y-axis and parallel to the work surface 1 
in the direction of the z-axis. The rotary movement 6 of a puller drive 19 
takes place as additional transport movement for the sewing material. 
Below the work plane 1 there operates with the rotary movement 7 the 
looper drive 20 for the underthread 84, which is pulled by means of the 
looper drive 20 through the loop formed by means of the needle 10 from the 
upper thread 40. The rectangular movement 8 of a lower transport drive 21 
behind the needle 10 and the rectangular movement 9 of a lower transport 
drive 23 in front of the needle 10 take place in each case in closed 
rectangular movements parallel to the work plane 1 and vertical to it 
respectively, i.e. in the direction of the y- and z-axes. The movements 2 
to 9 shown characterize the maximum degree of freedom of the sewing device 
which is necessary for complex stitch geometries, for instance faggot 
stitch. The most frequent seam forms and stitch geometries, however, 
require only a partial region of the movements 2 to 9 shown. 
The sewing process requires substantial synchronism of the individual 
movements 2 to 9. Corresponding to the specific sewing task, the 
individual movements 2 to 9 must take place synchronously in a 
predetermined ratio as a function of the stroke 2 of the needle 10, which 
serves as guide variable. In general, the ratio of the movements 2 to 9 of 
the elements with respect to each other can be indicated as follows: 
The reciprocation 2 of the needle 10 corresponds to the movement of 
rotation 7 of the looper drive 20, the vertical presser-foot movement 5V, 
the horizontal presser-foot movement 5H, the tensioning movement 4 of the 
upperthread 40 and the rectangular movement 8 of the lower transport drive 
21 behind the needle 10. To the upward and downward reciprocation 2 of the 
needle 10 there furthermore correspond the deflection movement 3 of the 
needle 10 which effects the zigzag movement, multiplied by a factor the 
rectangular movement of the lower transport drive in front of the needle 
10, multiplied by another factor and the movement of rotation 6 of the 
puller drive 19 multiplied by still another factor, dependence on the 
diameter of the puller 31. 
An individual drive 15 to 23 is provided for each of the above-indicated 
elements having the movements 2 to 9, so that the elements can be moved 
independently of each other. For the synchronizing of the individual 
drives 15 to 23 with each other a control device 11, 12, 33 is provided 
which may be of electronic or hydraulic construction. The drives 15 to 23 
are adapted, by means of the control device 11, 12, 33, to the forces to 
be transmitted by the movements 2 to 9 of the individual elements, which 
forces are influenced as a function of the properties of the material, for 
instance the thickness and the material of the fabric and the 
manufacturing method selected, for instance the stitch geometry. In this 
connection, there is a large force transmission range for the upward and 
downward reciprocation 2 of the needle 10, depending on the number of 
layers of material and the types of material, for the rectangular movement 
9 of the lower transport drive 23 in front of the needle 10, depending on 
the length and/or the weight of the sewing material to be sewn, and for 
the upper transport drive 23 formed on the upper presser foot 32. A small 
force transmission range is necessary for the tensioning movement 4 of the 
upper thread 40 by the bobbin case opener 39, the vertical presser-foot 
movement 5V, the rotary movement 7 of the looper drive 20, the zigzag 
movement-producing deflection movement 3 of the needle 10, the rectangular 
movement 8 of the lower transport drive 21 behind the needle 10, and the 
rectangular movement 6 of the puller drive 19. 
FIG. 2 shows the control of the various individual drives by means of a 
hydraulic pulse generator 11 which is driven by an electric or hydraulic 
motor 12. The hydraulic pulse generator 11 converts a continuous hydraulic 
stream 13 fed to it into a plurality of pulsating hydraulic streams which 
flow in the lines 14 shown in FIG. 3. For the lines 14 flexible hose 
connections are used. The individual pulses fed to the drives 15 to 23 
which are converted by the pulse generator 11 in accordance with the 
required speed of rotation are infinitely adjustable over a frequency 
range of 0 to 50 kHz and over any amplitude. The continuous flow of the 
hydraulic streams 13 can be produced either via a commercial hydraulic 
system decentrally for an individual sewing device or centrally for a 
plurality of sewing devices. The needle drive 15 effects the upward and 
downward reciprocation 2 of the needle 10 carried out perpendicular to the 
work plane 1 and is developed as a double-acting hydraulic cylinder. The 
drive 16 for the deflection 3 of the needle 10 which effects a zigzag 
movement is also developed as double-acting hydraulic cylinder. The 
deflection movement 3 of the needle 10 is effected via the zigzag drive 
16, which is fastened on the housing for the needle drive 15. The zigzag 
drive 16 for the deflection movement 3 moves the needle drive 15 for the 
reciprocation 2 of the needle in accordance with the stitch geometry 
selected. By means of the presser drive 17, the vertical presser foot 
movement 5V takes place perpendicular to the work plane 1, the pressing-on 
of the presser foot 32 being effected by the hydraulic system pressure and 
the release of the pressure foot 32 by a spring. A single-acting cylinder 
is used for the presser drive 17. The presser drive 18 effects the 
horizontal presser-foot movement 5H for the upper transport drive 22 and 
is--in the same way as the transport drives 21 and 23 for the rectangular 
movements 8 and 9 of the underthread 84--developed as a double-acting 
hydraulic cylinder. For the puller drive 19, a hydraulic motor developed 
as stepping motor is provided. For the looper drive 20, a hydromotor for 
looper drive (step stitch) and a double-acting hydraulic cylinder for the 
looper movement (chain stitch) are used. 
FIG. 3 shows one embodiment of the sewing device together with its drive 
elements, not all the drive elements, however, being shown. The pulse 
generator 11 and the electric or hydraulic motor 12 are mounted within a 
frame 24 and are connected directly to one another. The pulse generator 11 
is connected via a control line 35 with a foot pedal 34 for the operating 
of the sewing device. Furthermore, the pulse generator 11 is connected via 
the plurality of hose lines 14 with the individual drives 15 to 23. 
Finally, the hydraulic stream 13 is fed from a hydraulic unit 33 via 
another hose line 13'. 
Above the frame 24, there is the sewing head 25 which is formed of a sewing 
head upper part 26 and a sewing head lower part 27, between which the 
workplane 1 is located. The sewing head upper part 26 is fastened to an 
upper bracket arm 28. The sewing head lower part is fastened to a further, 
lower bracket arm 29. The two substantially horizontally extending bracket 
arms 28, 29 are arranged on a vertical stand 30 which is fastened on the 
upper workplate of the frame 24. The hose lines 14 to the individual 
drives 15 to 23 extend through the stand 30 and the bracket arms 28, 29. 
FIG. 4 shows the sewing head 25, consisting of sewing head upper part 26 
and sewing head lower part 27 according to FIG. 3, in a larger, more 
detailed view. In accordance therewith, on the end of the upper bracket 
arm 29 there is flanged a housing 36 which receives the needle drive 15 
for the reciprocation 2 of the needle 10. In FIG. 4, behind the housing 36 
there is shown the housing 37 which receives the zigzag drive 16 for the 
deflection motion 3 of the needle 10. The hoses 14 leading to the 
hydraulic drives 15, 16 are fed within the stand 30 and the upper bracket 
arm 28 and emerge from it in order to be introduced from above into the 
housings 36, 37. 
Below the needle 10 there extends the presser foot 32, whose presser foot 
drives 17, 18 are in a housing 38 which is flanged to the bottom of the 
upper bracket arm 28. Further hoses 14 are conducted to the presser foot 
drives 17, 18 arranged in the housing 38. 
Above the housing 38 for the hydraulic presser foot drives 17, 18 a bobbin 
case opener 39 which effects the tensioning movement 4 for the upper 
thread 40 is mounted on the upper bracket arm 28. The upper thread is fed 
from a thread bobbin 41, via guide eyes 42 and the bobbin case opener 39 
as well as another guide eye 42, to the needle 10. 
Below the thread bobbin 41 and below the upper bracket arm 28, the puller 
drive 19 for the puller 31 is mounted within a housing 43. Another 
hydraulic line 14 is conducted to the hydraulic puller drive 19. The 
hydraulic puller drive 19 actuates the puller 31 for the rotary movement 6 
as additional transport movement of the sewing material. 
The housings 36, 37 for the hydraulic needle drives 15, 16, the thread 
bobbin 41 and parts of the housings 48 and 43 for the hydraulic presser 
foot drive 17 and the hydraulic puller drive 19 are arranged within a 
box-like cover 44, which thus encloses the entire sewing head upper part 
26. 
The sewing head bottom part 27 is enclosed in another cover 45 which is 
located below the work plane 1 formed of a work plate 1' for the 
supporting of the sewing material. Below the work plate 1' there is 
provided on a vertical extension 29' of the lower bracket arm 29, the 
hydraulic transport drive 21 for the lower transport device behind the 
needle. For the transport drive 21, a hose 14 is conducted through the 
lower bracket arm 29. On the free end of the lower bracket arm the 
hydraulic looper drive 20 for the underthread looper 46 is seated. 
In FIGS. 5 and 6 the hydraulic needle drives 15, 16 for the reciprocation 2 
and deflection movement 3 respectively of the needle 10 are shown. The 
housing 37 for the zigzag drive 16 is arranged firmly on the upper bracket 
arm 28. On the housing 37 there is arranged a swing frame 47 for a swivel 
shaft 48 in which the housing 36 for the needle drive 15 is swingably 
mounted. Between the two housings 36 and 37 an L-shaped support 49 is 
fastened to the swing frame 47 and L-shaped support 49 is provided in its 
lower part with two horizontal extensions 50 which are spaced apart from 
each other and between which the needle 10 is freely guided. The two 
extensions 50 bear on their outer sides stub shafts 51 on which two bell 
crank levers 52 are swingably mounted. The vertical arms of the bell crank 
levers 52 are provided at their ends with slots 53 into which there extend 
pins 54 which are arranged fixed in position on the outside of the housing 
36 of the needle drive 15. The horizontal arms of the bell cranks levers 
52 also have slots 55 into which a swivel shaft is engaged which is 
arranged on the free end of the piston rod 56 of the hydraulic zigzag 
drive 16. 
The hydraulic zigzag drive 16 is formed by a double-acting hydraulic 
cylinder 57 whose cylindrical space is divided by a sealing disk 58 into 
two chambers 59, 60. Within each chamber a piston 61, 62 is arranged on 
the piston rod 56 which passes through it. Each chamber 59, 60 has an 
inlet port 63, 64 and an outlet port 65, 66. 
A leakage oil port 67, 68 lies on each rear side of each piston 61, 62. 
The double-acting hydraulic cylinder 57 described operates as follows: 
Upon the entrance of pressure oil into the inlet port 63, the output port 
65 associated with the upper chamber 59 is closed. At the same time, the 
input port 64 associated with the lower chamber 60 is closed, but the 
associated outlet port 66 is opened. In this way, under the action of the 
pressure oil flowing into the upper chamber 59 the piston 61 and thus the 
piston rod 56 are raised. The bell crank lever 52 is swung in 
counterclockwise direction. The housing 36 of the needle drive 15 is swung 
to the left around the swivel pin 48 (FIG. 6), as a result of which the 
needle 10 is deflected to the left (x-axis). At the same time, the 
pressure oil is forced out of the chamber 60 by the piston 62 through the 
output port 66 until the upper edge of the piston 62, as control edge, 
closes off the outlet port 66. The pressure oil then still present in the 
chamber 60 serves as buffer. Pressure oil is now fed through the inlet 
port 64 to the lower chamber 60, and the outlet port 66 of the lower 
chamber is closed. At the same time, the outlet port of the upper chamber 
59 is opened and the inlet port 63 associated with it is closed. The 
piston 62 moves downward under the action of the pressure which builds up 
in the chamber 60 and at the same time, under the action of the upper 
piston 61, the pressure oil is forced out of the chamber 59 through the 
outlet port 65 until the latter is closed by the con edge of the upper 
piston 61. In this way, the bell crank 52 is swung in clockwise direction, 
i.e. the needle is deflected to the right (in FIG. 6). By this right-left 
deflection of the needle 10, the desired zigzag movement of needle 10 is 
produced. Through the corresponding leakage-oil ports 67, 68 the spaces 
lying on the rear of the pistons 61, 62 are vented and any leakage oil 
present is led off here. 
The needle drive 15 for reciprocation 2, which drive is arranged in the 36, 
operates in the same way with respect to the vertical upward and downward 
movement of the piston rod 56' as the hydraulic zigzag drive 16 for the 
deflection movement 3. In this way the desired vertical upward and 
downward movement of the needle 10 is produced, the needle being fastened 
to the lower end of the piston rod 56' via a needle mount 10'. To be sure, 
in the case of the zigzag drive 16 a stroke height adjustment is provided 
for the needle 10, constructed as follows: The outlet port 66 comprises 
three outlet ports 69 to 71 each of which leads out of the lower chamber 
60 and which are provided with shut-off valves. In the embodiment shown, 
the shut-off valve of the upper outlet port 69 is open, while the shut-off 
valves of the other outlet ports 70, 71 are closed. Thus, upon the upward 
movement of the piston 62, a pressure cushion is formed only when the 
outlet port 69 is reached by the control edge of the piston 62. The needle 
10 carries out a maximum stroke movement. If the shut-off valve of the 
upper outlet port 69 is closed and the shut-off valve of the lower outlet 
port 71 opened, the pressure cushion is built up already when the control 
edge of the piston 62 reaches the outlet port 71, so that the needle 10 
can only carry out a minimum stroke movement. 
All inlet ports 63, 64, outlet ports 65, 66 and outlet ports 69, 71 are 
connected to the hydraulic control device by corresponding hoses 14. 
FIGS. 7 and 8 show the looper drive 20 for the underthread looper 46. The 
transport drive 21 is not shown here since the same operating principle is 
used as in the case of the drives 15, 16 of the needle 10. The looper 
drive 20 has a housing 72 which is firmly connected to the lower bracket 
arm 29. Within the housing 72 there is mounted a horizontally arranged 
shaft 73 which bears at its free end, the underthread bobbin 74 which is 
developed in traditional manner and is arranged below the needle 10. The 
shaft 73 has, between its supports 75, two sealing disks 76 between which 
there is arranged a swing vane 77 which is rigidly connected to the shaft 
73. The swing vane 77 is mounted, sealed off on all sides, within a 
housing opening 78 of circular cross section, the lateral sealing being 
effected by the sealing disks 76. As shown in FIG. 8, the housing opening 
78 has on its bottom side a ridge-shaped nose 79 which rests in sealed 
manner against the shaft 73. On both sides of the sealing point, inlet 
ports 80, 81 are developed. In the central plane, at the 90.degree. and 
270.degree. positions of the swing vane 77, outlet ports 82, 83 are 
connected to the housing opening 78. 
The looper drive 20 described for the underthread looper 74 operates as 
follows: 
Upon the feeding of pressure oil through the inlet port 81, with the inlet 
port 80 closed and the outlet port 83 closed, a pressure-oil cushion is 
built up below the swing vane 77 so that the latter is swung in 
counterclockwise direction until its leading control edge closes off the 
outlet port 82. An oil cushion is built up in this case below the swing 
vane 77 so that the latter comes to a stop. The control is now reversed in 
the manner that the inlet port 80 is opened and the outlet port 81 is 
closed. At the same time, the outlet port 83 is opened and the outlet port 
82 is closed. Under the action of the pressure oil cushion which now 
builds up below the swing vane 77, the swing vane 77 is swung back in 
clockwise direction until its leading control edge closes the outlet port 
83. In this way, the underthread bobbin 74 is cyclically swung. The 
feeding and removal of the pressure oil to and from the ports 80, 81 and 
outlet ports 82, 83 is effected, controlled by the control device, by 
means of the connected pressure-oil hose 14. 
The presser foot drives 17, 18 and the transport drives 21 to 23 are 
developed in the same manner as the needle drives 15, 16 and looper drive 
20 described in detail above. The puller drive 19 is developed as a known 
hydromotor. The control lines shown for the pressure oil have been shown 
only in principle. As the specific embodiments in accordance with FIGS. 5 
to 8 show, actually the number of flexible hose lines 14 which are 
conducted to the individual drives 15 to 23 is much larger. 
The development of the individual hydraulic drives 15 to 23 makes it 
possible synchronously to control the individual movements via the pulse 
generator 11 from the control device 11, 12, 33 separately from each other 
via separate lines 14 so that the separate drives 15 to 23 can be adapted 
as desired to the forces and/or speeds to be transmitted by them.