Sewing machine, sewing unit with such sewing machine and method for operating sewing machine

Abstract

To develop a sewing machine capable of accurately sewing workpieces having different thicknesses and / or different numbers of layers in a flexible manner.SOLUTION: The sewing machine has a needle plate (3a) and a workpiece presser foot (13) for performing a stroke movement for pressing a workpiece on the needle plate (3a) during a sewing procedure. A driven stroke amplitude adjustment device (17) serves to set the stroke amplitude of the stroke movement of the workpiece presser foot between a top dead center and a bottom dead center. A driven stroke level adjustment device serves to set the stroke level of the stroke movement of the workpiece presser foot (13) relative to the needle plate (3a). A control / regulation device (11) is in signal communication with the stroke amplitude adjustment device (17) and the stroke level adjustment device. Furthermore, there is provided a possible operating method for the sewing machine. This provides a sewing machine capable of accurately sewing workpieces having different thicknesses and / or different numbers of layers in a flexible manner.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a sewing machine. Furthermore, the invention relates to a sewing unit comprising such a sewing machine and to a method of operating such a sewing machine. [Background technology]

[0002] Sewing machines are known from DE 10 200 04 133 A1 and DE 10 200 04 14 A2. A sewing unit comprising a sewing machine is known from DE 10 200 04 14 A1. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] EP 3 556 923 B1 [Patent Document 2] EP 3 088 591 B1 [Patent Document 3] EP 3 088 587 B1 Summary of the Invention [Problem to be solved by the invention]

[0004] The object of the present invention is to develop a sewing machine which is capable of accurately sewing workpieces of different thicknesses and / or different numbers of layers in a flexible manner. [Means for solving the problem]

[0005] According to the invention, this object is achieved by a sewing machine having the features set forth in claim 1.

[0006] According to the present invention, it is recognized that designing a sewing machine with a driven stroke (or lifting) amplitude adjustment device and a driven stroke (or lifting) level adjustment device makes it possible to specify the stroke amplitude and stroke level of the workpiece presser foot, respectively, in a particularly independent manner. Thus, the sewing machine can be designed so that the stroke amplitude and stroke level of the workpiece presser foot can be specified independently by one stroke amplitude adjustment device and another stroke level adjustment device. Such specification of one stroke amplitude and specification of the other stroke level can be performed independently. The stroke path of the workpiece presser foot during the sewing operation can be specified over a very wide range. As long as the movement of the workpiece presser foot, i.e., the stroke or lifting motion of the workpiece presser foot, is linked or synchronized with the movement of the stitch-forming tool of the sewing machine, intermittent or periodic stroke or lifting motion of the workpiece presser foot is possible, which conforms to the adjusted "stroke amplitude" and "stroke level" parameters, respectively. The stroke amplitude adjustment device can include a lifting cam, which can be particularly designed as a cam disc, and / or a plate gear, which can also be particularly designed as a cam disc. The stroke level adjustment device can include a lifter cam. The pressure action of the workpiece pressure foot can take the form of pressing against the workpiece. Alternatively or additionally, the pressure action of the workpiece pressure foot can be such that the workpiece pressure foot does not contact the workpiece, but simply acts to prevent the workpiece from undesirably escaping upward within the stroke dimension.

[0007] The drive of the stroke amplitude adjustment device and / or the stroke level adjustment device can be designed as a stepper motor.

[0008] The stroking motion of the workpiece foot may be continuous and / or oscillating.

[0009] The sensor according to claim 2 enables controlled operation of a stroke drive of a sewing machine, the stroke drive comprising a stroke amplitude adjustment device and a stroke level adjustment device. This sensor can measure, in particular, the distance from a component of the workpiece presser foot to the throat plate. In particular, direct measurement of the actual stroke of the workpiece presser foot on the throat plate is possible. Alternatively, this sensor can measure the actual position of a gear or a gear or a component of this gear used during the stroke displacement of the workpiece presser foot. Alternatively or additionally, an encoder, in particular a stepper motor encoder, for the sewing drive and / or for the drive of the stroke amplitude adjustment device and / or for the drive of the stroke level adjustment device can be provided as a sensor for detecting the actual stroke position of the workpiece presser foot. This sensor can be designed as an optical sensor and / or a capacitive sensor.

[0010] The actual position of the workpiece presser foot on the throat plate can be detected by a sensor when the workpiece is being pressed by the workpiece presser foot, and can also be detected by detecting the motor current of the workpiece presser foot drive.

[0011] The spring preload of the workpiece presser foot as claimed in claim 3 allows the foot to be inserted as intended (assuming it is applying pressure to the workpiece while holding it down), so that the foot of the workpiece presser foot is not positioned at an undesirable depth relative to the throat plate.

[0012] A setting device as claimed in claim 4 allows the specification of the force associated with the insertion process. The stroke level adjustment device can simultaneously take over the function of such a setting device.

[0013] The advantages of the sewing unit according to claim 5 correspond to those already described above for the sewing machine. A sewing unit with a sewing machine is basically known from DE 10 200 04 133 A1. In addition to the sewing machine, the sewing unit can also comprise a workpiece holder, which defines a sewing area in which the workpiece is sewn by the sewing machine. Such a workpiece holder can be designed as a clamp. Alternatively or additionally, such a workpiece holder can be designed as a workpiece holder frame.

[0014] A further object of the present invention is to provide an operating method that can be carried out on a sewing machine according to the present invention.

[0015] The operating method according to claim 6 is characterized in that the stroke level exactly follows the target value specification, independently of the absolute value of the specifically specified stroke amplitude.

[0016] The operating method according to claim 7 is characterized in that the stroke amplitude precisely follows the target value specification, independently of the absolute value of the specifically specified stroke level.

[0017] The method of operation as claimed in claim 8 provides for adaptation of the stroke level to changing demands during the stitching movement while keeping the stroke amplitude the same.

[0018] The operating method according to claim 9 provides for adaptation of the stroke amplitude to changing sewing requirements during the sewing movement without changing the stroke position of the workpiece presser foot in the bottom dead center region.

[0019] The operating method according to claim 10 allows the workpiece presser foot to be lifted by a stroke level adjusting device. An additional lifter drive device can be omitted. The stroke amplitude specified at the start of this operating method can also have the value 0.

[0020] When the workpiece presser foot is raised by this operating method, the maximum stroke amplitude can be further specified by the stroke amplitude adjusting device.

[0021] These methods of operation can also be combined: for example, if different stroke amplitudes and / or different stroke levels are specified, it can be ensured that in each case, after the specified value for the first parameter is changed, the complementary parameters "stroke level" and "stroke amplitude" remain within predetermined tolerance limits, i.e. do not change in an undesirable way.

[0022] Exemplary embodiments of the invention will now be described in more detail with reference to the drawings. [Brief explanation of the drawings]

[0023] [Figure 1] 1 is a perspective view of a sewing unit including a sewing machine and an xy workpiece holder for driving movement of a workpiece held in position along two horizontal dimensions. [Figure 2] FIG. 1 is a perspective view of an assembly of drive components of a sewing machine for driving a workpiece presser foot, including a drive stroke amplitude adjustment for setting the stroke amplitude of the stroke movement of the workpiece presser foot, and a drive stroke level adjustment for setting the stroke level of the stroke movement of the workpiece presser foot. [Figure 3] 3 is a perspective view of the drive components of FIG. 2, seen from the opposite direction to FIG. 2. [Figure 4] 4 is a perspective view showing a cross section of the drive part on the workpiece presser foot side of the drive part assembly of FIG. 2, again seen from the direction IV in FIG. 2. FIG. [Figure 5] 5 is a perspective view of the drive unit of FIG. 4, again seen from diagonally below in the opposite direction to that of FIG. 4. FIG. [Figure 6] 1 is a longitudinal cross-sectional view through a workpiece presser foot and adjacent drive components of the drive component assembly, taken along a cutting plane perpendicular to the drive shaft and adjustment shaft of the drive component assembly. FIG. [Figure 7]7 is a cross-sectional view taken along a cutting plane parallel to the cross-sectional view of FIG. 6, for explaining a cam disk of the stroke amplitude adjusting device. FIG. [Figure 8] FIG. 8 is a cross-sectional view similar to FIG. 7 for illustrating a cam disk of the stroke level adjusting device. [Figure 9] FIG. 10 is a schematic diagram for explaining setting parameters of an adjusting device of a driving part assembly. [Figure 10A] 2 and 3, showing the drive assembly with the stroke "Y" set by the stroke amplitude adjustment device at the momentary "top dead center" position (part 1). [Figure 10B] 2 and 3, but showing the drive assembly in its momentary "top dead center" position with the stroke "Y" set by the stroke amplitude adjustment device. [Figure 11A] FIG. 11 is a first view of the drive assembly of FIG. 10 again at stroke position "Y," this time in the instantaneous "bottom dead center" position. [Figure 11B] FIG. 11 is a second view of the drive assembly of FIG. 10 again at stroke position "Y," this time in the instantaneous "bottom dead center" position. [Figure 12A] 12 is a view similar to FIGS. 2 and 3 again showing the drive component assembly at stroke amplitude position "Y" and a stroke level position of the stroke level adjustment device, which is larger than that of FIGS. 10 and 11, again at top dead center (part 1); [Figure 12B] 12 is a view similar to FIGS. 2 and 3 again showing the drive component assembly at stroke amplitude position "Y" and a stroke level position (part 2) of the stroke level adjustment device, again at top dead center, which is larger than that of FIGS. 10 and 11; [Figure 13A] FIG. 13 is a first view of the drive assembly of FIG. 12 shown in an instantaneous "bottom dead center" position. [Figure 13B] FIG. 13 is a second view of the drive assembly of FIG. 12 shown in an instantaneous "bottom dead center" position. [Figure 14]14 is a view similar to FIG. 9, illustrating schematically the application of a stroke action of the workpiece presser foot controlled by the drive component assembly, first to the instantaneous positions of FIGS. 10 and 11, and then to the instantaneous positions of FIGS. 12 and 13. [Figure 15A] 11 is a view similar to FIG. 10 showing the drive component assembly at stroke amplitude position "X" at instantaneous "top dead center" position (part 1); [Figure 15B] FIG. 11 is a second view similar to FIG. 10 showing the drive component assembly at stroke amplitude position "X" at the instantaneous "top dead center" position. [Figure 16A] 16A / B are diagrams (part 1) showing the drive component assembly of FIG. 15 in a momentary "bottom dead center" position. [Figure 16B] 16A / B are views (part 2) of the drive assembly of FIG. 15 in a momentary "bottom dead center" position. [Figure 17] 15 and 16 are views similar to FIG. 14 and illustrating, in a simplified manner, further application of the stroke action of the workpiece presser foot by the drive component assembly, first in the instantaneous positions of FIGS. 10 and 11, and then in the instantaneous positions of FIGS. 15 and 16. [Figure 18A] FIG. 4 is a view similar to FIG. 2 or 3 showing the drive component assembly with the workpiece presser foot in the raised position (part 1); [Figure 18B] FIG. 4 is a view similar to FIG. 2 or 3 showing the drive component assembly with the workpiece presser foot in the elevated position (part 2); [Figure 19] 14 and 17, showing the application of the stroke action of the workpiece presser foot with the drive assembly in the positions of FIGS. 10 and 11 on the one hand and in the lift position of FIG. 18 on the other hand. [Figure 20A]4 is a view similar to FIG. 2 or FIG. 3 showing the drive part assembly in the position of the stroke amplitude adjustment device on the one hand and the position of the stroke level adjustment device on the other hand (part 1), in which the workpiece presser foot is placed on the throat plate and is preloaded against it by the bearing spring. [Figure 20B] 4 is a view similar to FIG. 2 or FIG. 3 showing the drive part assembly in the position of the stroke amplitude adjustment device on the one hand and the position of the stroke level adjustment device on the other hand (part 2), in which the workpiece presser foot is placed on the throat plate and is preloaded against it by the bearing spring. DETAILED DESCRIPTION OF THE INVENTION

[0024] The sewing unit 1, shown generally in Figure 1, comprises a sewing machine 2 for sewing two workpiece items.

[0025] The sewing machine 2 sews a workpiece (item to be sewn) by forming at least one stitch in the seam forming area 3. Around the seam forming area 3, the sewing machine 2 has a throat plate 3a on which the workpiece is placed.

[0026] The workpiece is transported to the seam forming area 3 during seam formation by a workpiece holder 4 in the form of a workpiece clamp having a one-piece lower clamping portion 5 and two-piece upper clamping portions 6a, 6b. The upper clamping portion 6a, shown in the upper left corner of Figure 1, is shown raised from the lower clamping portion 5 of Figure 1, while the other upper clamping portion 6b is shown lowered onto the lower clamping portion 5 of Figure 1 to clamp the workpiece.

[0027] The clamping portions 5, 6 of the workpiece holder 4 enclose a substantially rectangular sewing area 7 within which a seam can be formed in the workpiece using the sewing unit 1.

[0028] Depending on the design of the sewing unit 1, instead of the above-described workpiece clamp with clamping parts 5, 6, other clamping systems, in particular interchangeable clamping systems, can also be used.

[0029] In the following, to make it easier to understand the positional relationships, the figures are described using a Cartesian coordinate system xyz. The x and y coordinates define the plane in which the workpiece is placed. The y coordinate extends parallel to the arm 8 of the sewing machine 2. The z coordinate extends perpendicular to the x and y plane in which the workpiece is placed.

[0030] Typical xy sewing area sizes vary depending on the design of the sewing unit 1 (extension in x direction, extension in xy direction): 150mmx100mm, 220mmx100mm, 250mmx160mm, 300mmx200mm.

[0031] To move the sewing area 7 relative to the seam forming area 3, the workpiece holder 4 is provided with an x-drive with an x-guide 9 and a y-drive with a y-guide 10. The x-drive can be operated independently of the y-drive. A control / regulation device 11 of the sewing unit 1 serves this purpose.

[0032] A clamp drive 12 having independent drive elements 12a, 12b (FIG. 1 shows the drive element 12b assigned to the upper clamp part 6b) serves to raise and lower the upper clamp parts 6a, 6b. The clamp drive 12 is also in signal communication with the control / regulation device 11.

[0033] Furthermore, the sewing machine 2 has a workpiece presser foot 13, the foot 14 of which (see FIG. 2) includes a passage sleeve for the sewing machine's sewing needle 15. Instead of such a workpiece presser foot 13 designed as a walking foot, it is also possible to use a presser foot with a plate-shaped foot instead of a passage sleeve, depending on the design of the sewing machine 2.

[0034] The workpiece presser foot 13 is designed to perform intermittent stroke movements to press the workpiece down onto the throat plate 3a, particularly during the sewing procedure.

[0035] 2 and 3 show the stroke drive 16 of the workpiece presser foot 13 in detail.

[0036] The stroke drive unit 16 has a stroke amplitude adjustment device 17 for setting the stroke amplitude HA of the stroke movement of the workpiece presser foot 13 between top dead center OT (see also FIG. 9) and bottom dead center UT. Furthermore, the stroke drive unit 16 has a stroke level adjustment device 18 for setting the stroke level HN of the stroke movement of the workpiece presser foot 13 relative to the throat plate 3a.

[0037] These stroke movement parameters, namely the stroke amplitude HA and the stroke level HN, are clearly shown in Figure 9. Figure 9 shows the sinusoidal vibration stroke H of the workpiece pressure foot 13 (not shown) as a function of time t.

[0038] The stroke amplitude HA=X is shown by a solid line. A smaller stroke amplitude HA=Y is shown by a dashed line. The adjustment between these two exemplary stroke amplitudes X and Y is carried out by a stroke amplitude adjusting device 17. For this purpose, the stroke amplitude adjusting device 17 comprises a stroke gear 19 in the form of a plate gear (see FIGS. 2 and 3). The stroke gear 19 is driven via a cam 20, which in turn is driven by an upper shaft 21 of the sewing machine, which extends in the arm 8. The sewing machine is shown diagrammatically in cross section in FIG. 2. The upper shaft 21 is driven by the sewing machine drive. On the driven side, the stroke gear 19 acts on a stroke shaft 22 of the stroke drive 16, which in turn acts on a presser foot rod 25 of the workpiece presser foot 13 via a lever 23 and an articulated chain 24.

[0039] The stroke gear 19 is adjusted via an amplitude adjustment shaft 26 which is adjusted via an adjusting lever 27 (see FIG. 7) and a cam disc 28 which is driven by a stepping motor 29 for setting the stroke amplitude of the stroke amplitude adjustment device 17. The preload spring on which the cam disc 28 acts is shown in FIG. 2, as well as in the other corresponding figures, in the released state, i.e. without preloaded operating state.

[0040] The stroke level adjustment device 18 serves, on the one hand, to specify the respective stroke level HN and, on the other hand, to raise the workpiece presser foot 13, in particular at the start and end of a sewing procedure.

[0041] The stroke level adjustment device 18 includes a lifter shaft 30 (see particularly FIG. 4) which cooperates with the presser foot rod 25 to lift the workpiece presser foot 13 via a lifter lever 31 on a positioning cam 32.

[0042] The shafts 22, 26, and 30 extend parallel to the upper shaft 21 along the y direction.

[0043] The stroke drive 16 of the workpiece presser foot 13 is guided via a linear guide 33 .

[0044] The stroke drive unit 16 is prevented from twisting by a slide block 34 and a Z guide 35 shown in Figure 4, which are fixed to the frame of the sewing machine 2. Another Z guide 36 for the presser foot rod 25 is also shown in Figure 4.

[0045] A pressure bracket 37 articulated to the lifter lever 31 keeps the preload of a compression spring 38 between the pressure bracket 37 and the presser foot rod 25 constant unless a positive Z force is exerted by the workpiece on the foot 14 of the workpiece presser foot 13. Such a positive Z force exerted on the foot 14 causes a corresponding compression of the compression spring 38, allowing the workpiece presser foot 13 to flex in response to such positive Z force and insert toward the spring bushing 39. In practice, a combination or spring assembly of compression springs functions as the compression spring 38, as can be seen, for example, from the cross-sectional view of FIG. 6.

[0046] The lifter shaft 30 of the stroke level adjustment device 18 is operatively connected to a stroke level cam disc 41 (see in particular FIG. 8) via an adjustment lever 40 at the end of the lifter shaft 30 opposite the lifter lever 31. A comparable cam disc is known from US Pat. No. 5,649,999.

[0047] The stroke level cam disc 41 is driven via a stroke level servomotor or lifter servomotor 42, which is also designed as a stepper motor. The stroke level cam disc 41 has several functions depending on the direction of rotation in which it is driven. During rotation in one direction, a change in the stroke level HN occurs, which can be accompanied by a change in the preload of the compression spring 38. The stroke level adjusting device 18 therefore simultaneously functions as a setting device for specifying the preload of at least one compression spring 38. During rotation of the stroke level cam disc 41 in the opposite direction of rotation, the workpiece presser foot 13 is lifted.

[0048] The holding action of the workpiece pressure foot 13 can be performed as an actual holding down of the workpiece. Alternatively or additionally, the holding action of the workpiece pressure foot 13 can be performed such that the workpiece pressure foot 13 does not contact the workpiece, but merely prevents the workpiece from undesirably escaping upward, i.e., in the positive Z direction. The stroke movement of the workpiece pressure foot results in intermittent, and in particular periodic, holding down of the workpiece.

[0049] The positive Z distance between the workpiece presser foot 13 and the throat plate 3a at the bottom dead center of the stroke travel can be set via an adjustable stop which can be fixedly arranged on the frame and can be designed to be adjustable relative to the frame between different stop positions.

[0050] The higher this z-position of the workpiece pressure foot 13 at the bottom dead center of its stroke travel is set via the stop, the more compressed the compression spring 38 will be as long as the pressure bracket 37 remains at the z-position. The additional compression of the compression spring 38 increases the initial pressure that the compressed workpiece must exert against the workpiece pressure foot 13 to displace the workpiece pressure foot 13 in the positive z-direction against the compressive force of the compression spring 38. By setting the z-position of the pressure bracket 37, this initial pressure that the workpiece must overcome against the workpiece pressure foot 13 can be set at the bottom dead center of its stroke travel. This can be accomplished by the stroke level adjustment device 18, lifter shaft 30, and lifter lever 31, as already described above.

[0051] The Z distance between the workpiece presser foot 13 and the needle plate 3a can be specified in the range of 0 mm to 5 mm, for example, in the range of 0 mm to 2 mm, or in the range of 0 mm to 1 mm via a stop body.

[0052] The sensor 43 of the sewing machine 2 serves to detect the actual stroke position of the workpiece presser foot 13 on the stitch plate 3a. The sensor 43 can be designed as an inductive and / or optical sensor, in particular for measuring the distance from parts of the workpiece presser foot 13 to the stitch plate 3a. Alternatively, the sensor 43 can be of a capacitive design, for example, for measuring the actual position of parts of the stroke drive 16 or of a stroke displacement gear of the workpiece presser foot 13. Alternatively or additionally, the sensor 43 can also be designed as an encoder of at least one drive part of the stroke drive 16, in particular of the stepper motors 29 and 42.

[0053] The measurement accuracy of the distance measured by the sensor 43 can be at least 0.1 mm, 0.1 mm or more, 0.05 mm or more, for example, 0.01 mm.

[0054] The actual position of the drive components of the stroke drive 16 can also be obtained by detecting the motor current of at least one of the components of the stroke drive 16, in particular the stepper motor 29 or 42, with a sensor.

[0055] 2 to 8 show the stroke drive 16 or its components in the basic position. The stroke amplitude HA is 0 and the stroke level HN is also 0 or at a minimum. The workpiece presser foot 13 is therefore in a non-raised position relative to the throat plate 3a.

[0056] 10 is a diagram similar to FIG. 2A, showing the stroke drive 16 with stroke amplitude HA=Y and an instantaneous position of stroke level HN equal to stroke amplitude HA, with the workpiece presser foot 13 at "top dead center OT." This corresponds to instantaneous position "A" in the stroke diagram of FIG. 14, which, like FIG. 9, illustrates application of the stroke drive to the sewing unit 1. In this case, the stroke level HN is set so that the first layer of the single-layer workpiece NG1 is between the foot 14 of the workpiece presser foot 13 and the throat plate 3a.

[0057] In the instantaneous position of the stroke drive components in FIG. 10, the cam disc 28 of the stroke amplitude adjusting device 17 and the cam disc 41 of the stroke level adjusting device 18 are shifted accordingly, and the described stroke parameters HA, HN (HN1) are present.

[0058] Figure 11 shows the instantaneous position "B" of the stroke drive 16, which is also shown in the diagram of Figure 14. The stroke amplitude Y and stroke level HN1 are again present. The workpiece pressure foot 13 is at bottom dead center UT. In the instantaneous position of Figure 11, the cam positions of the two cam discs 28, 41 have not changed compared to the instantaneous position of Figure 10.

[0059] 12A / 12B again show the instantaneous position of the stroke drive 16 at stroke amplitude Y, but now with the stroke level HN2 enlarged and the workpiece presser foot 13 at top dead center OT. Figure 14 therefore shows the instantaneous position "C". The enlarged stroke level HN2 makes it possible to accommodate, under the workpiece presser foot 13, in addition to the single-layer workpiece NG1, two further layers of workpiece NG2 which are located above it and which are sewn to the workpiece NG1 during the sewing procedure.

[0060] In instantaneous position "C" of Figures 12A / 12B, the cam disc 41 is rotated counterclockwise compared to the position of Figures 10 and 11. The position of the stroke amplitude cam disc 28 is unchanged compared to Figures 10 and 11.

[0061] Figures 13A / 13B show the workpiece presser foot 13 in instantaneous position "D" in Figure 14, i.e. at stroke amplitude Y, stroke level HN2 and bottom dead center. Compared to Figures 12A / 12B, the positions of the cam discs 28 and 41 are unchanged.

[0062] During the transition between the instantaneous positions "B" and "C," the stroke level adjustment device is continuously transitioned from the stroke level HN1 to the larger stroke level HN2 by driving the stepper motor 42. This transition takes place during half a period of the stroke movement of the workpiece presser foot 13 between bottom dead center (position "B") and top dead center (position "C"), as shown in FIG. 14. In order for the stroke amplitude to remain unchanged during the transition from the stroke level HN1 to the larger stroke level HN2 and to remain equal to the value Y in each case, a readjustment of the stroke amplitude adjustment device 17 may be necessary, since the stroke amplitude may depend on the respective position of the stroke level adjustment device 18. The same applies to the readjustment of the stroke level after a change in the stroke amplitude.

[0063] In views similar to Figures 10 and 11, Figures 15 and 16 show a stroke drive 16 with a stroke amplitude HA=X, which is greater than the stroke amplitude Y for the instantaneous position of, for example, Figure 10. Figures 15A / 15B show the workpiece presser foot 13 at top dead center OT, and Figures 16A / 16B show the workpiece presser foot 13 at bottom dead center UT.

[0064] FIG. 15 shows the instantaneous position "E" illustrated in FIG. 17, and FIG. 16 shows the instantaneous position "F" again illustrated in FIG.

[0065] For example, in comparison with the instantaneous position of the stroke drive 16 in Figure 10, in the instantaneous position in Figure 15 the cam disc 28 of the stroke amplitude adjustment device 17 is displaced, in particular rotated clockwise, which causes a corresponding change in the stroke amplitude from stroke Y to the larger stroke X.

[0066] In the application example of FIG. 17, the parameter combinations HA=Y and HN=HN1 are initialized in a manner equivalent to the starting position of the application example of FIG. 14. In this case, instead of the single-layer workpiece NG1, two thinner workpiece portions NG1 and NG1' are sewn together. Then, between the final instantaneous position "B" and the initial instantaneous position "E" in the application example of FIG. 17, the stroke amplitude of value Y is shifted to a larger value X, and the stroke level is also shifted from value HN1 to a larger value HN2. In this subsequent application situation in the application example of FIG. 17, instead of the workpiece NG1, a further workpiece NG3 can be sewn onto the workpiece NG1', which is thicker than the workpiece NG1. During this sewing procedure, the foot 14 of the workpiece presser foot 13 is inserted to some extent into the workpiece NG3 in the region of the bottom dead center (position "F"), but this insertion can be compensated for by the compression spring 38 being spring-loaded inward accordingly. In particular, the stroke level and / or stroke amplitude can be increased so that fuzzy or soft workpieces are not pushed up in an undesirable manner via the workpiece pressure foot 13 during x-transport and / or y-transport via the workpiece clamp.

[0067] 18A / 18B show that the stroke drive 16 is in the momentary "lift" position. The stroke level adjustment device 18 is now moving to the "lift" position, i.e., momentary position G shown in FIG. 19. The stroke level is now at L, i.e., the lift stroke level. The initial sewing state in the application example of FIG. 19 corresponds to the situation of FIG. 17 with stroke level HN1 and stroke amplitude Y. To achieve momentary position G, the stroke amplitude is changed to a larger value.

[0068] 20A / 20B show the instantaneous positions of the stroke drive 16 and the workpiece presser foot 13 during insertion of the workpiece presser foot 13 into the spring bushing 39 or into the spring guide 44. The foot 14 presses against the throat plate 3a with a pressure or preload force determined by the compression spring 38. In the instantaneous positions of FIGS. 20A / 20B, the stroke amplitude HA is set to 0 and the stroke level HN is set to <0.

[0069] With particular reference to Figures 14, 17 and 19, the following operating methods can be implemented in combination with the above-mentioned application examples.

[0070] In the first operation method of the sewing machine 2 of the sewing unit 1, the stroke amplitude HA is specified by the stroke amplitude adjusting device 17. Furthermore, the target stroke level HN Soll The sensor 43 determines the actual level HN for the specified stroke amplitude HA. Ist The stroke level adjusting device 18 checks the actual stroke level HN Ist and target stroke level HN Soll The difference between HN Ist -HN Soll is adjusted until it is within the specified tolerance limits. In particular, the following applies:

[0071] (HN Ist -HN Soll ) 2 / (HN Ist +HN Soll ) 2 ≦10%.

[0072] The tolerance limit can be lower than 10%, for example 5%, 3%, 2%, or 1%, or even lower. The tolerance limit is usually higher than 0.01%. After setting, the sewing machine will operate with the stroke parameters set in this way.

[0073] In a further operating method, the stroke level HN is first specified via the stroke level adjustment device 18. Then, the target stroke amplitude HA Sollis specified, the actual amplitude HA that occurs for a specified stroke level HN Ist is measured by the sensor 43. The stroke amplitude adjusting device 17 then adjusts the difference HA Ist -HA Soll is adjusted until it is within the predetermined tolerance limits. Ist -HA Soll ) 2 / (HA Ist +HA Soll ) 2 For , the values ​​given above can again be applied as tolerance limits for the difference between the actual stroke level and the target stroke level. After adjustment, the sewing machine is operated with the stroke parameters thus set.

[0074] In a further method of operating the sewing machine 2, first, a first stroke level HN1 is set by the stroke level adjusting device 18. Then, a stroke amplitude HA is set by the stroke amplitude adjusting device 17. Next, the sewing machine 2 of the sewing unit 1 is operated along a first sewing path at the first stroke level HN1 and stroke amplitude. Next, a further stroke level HN2 different from the first stroke level HN1 is set by the stroke level adjusting device 18. Then, the sewing machine 2 of the sewing unit 1 is operated along a further sewing path at the further stroke level HN1 and stroke amplitude HA. This operating method has already been described with reference to FIG. 14.

[0075] In the further method of operating the sewing machine 2 of the sewing unit 1, first, a first stroke level HN1 is specified by the stroke level adjustment device 18. Furthermore, a first stroke amplitude HA=Y is specified by the stroke amplitude adjustment device 17. The sewing machine 2 is then operated along a first sewing path at the first stroke level HN1 and the first stroke amplitude Y. Then, a further stroke level HN2 different from the first stroke level HN1 is specified by the stroke level adjustment device 18. Furthermore, a further stroke amplitude HA=X different from the first stroke amplitude HA=Y is specified by the stroke amplitude adjustment device 17. The specification of the further stroke level HN2 and / or the extended stroke amplitude X is performed in such a way that the stroke positions "B" and "F" of the bottom dead center of the workpiece presser foot 13 remain constant within predetermined tolerance limits, regardless of the specified stroke amplitudes Y and X. The tolerance limits are related to the Z coordinate Z of the bottom dead center at positions "B" and "F". B , Z F Using (Z B -Z F ) 2 / (Z B +Z F ) 2 <10% can be applied. This tolerance limit can also assume other values, in particular values ​​less than 10%, as already explained with respect to the tolerance limits for the stroke level difference and the stroke amplitude difference. The sewing machine 2 of the sewing unit 1 is then operated along a further sewing path with a further stroke level HN2 and a further stroke amplitude X. This further application has already been explained in connection with FIG. 17.

[0076] In a further method of operating the sewing machine 2 of the sewing unit 1, first, at least one stroke level HN is specified by the stroke level adjusting device 18. Furthermore, at least one stroke amplitude HA is specified by the stroke amplitude adjusting device 17. Next, the sewing machine 2 is operated along at least one sewing path at the specified stroke level HN and the specified stroke amplitude HA. After operation, the workpiece presser foot 13 is raised by the stroke level adjusting device 18 to remove the workpiece.

[0077] Within the scope of the above-mentioned application, the preload of the compression spring 38 can also be set via the stroke level adjustment device 18, thereby achieving a defined insertion depth of the workpiece pressure foot 13 into the workpiece, particularly in the region of bottom dead center. This has already been explained with reference to FIG. 17, particularly in connection with position "F". [Explanation of symbols]

[0078] 1 sewing unit 2 sewing machines 3. Stitch formation area 3a Needle plate (stitch plate) 4 Workpiece holder 5, 6 Clamp section 6a, 6b Upper clamp part 7 Sewing area 8 Arm 9 x Guides 10 y guide 11 Control / regulation devices 12 Clamp drive unit 12a, 12b Drive parts 13 Workpiece presser foot 14 Foot 15 needles 16 stroke drive unit 17 Stroke amplitude adjustment device 18 Stroke level adjustment device 19 Stroke Gear 20 Cam 21 Upper Shaft 22 stroke shaft 23 Lever 24 Jointed Chain 25 Presser foot rod 26 Amplitude adjustment shaft 27 Adjustment lever 28 Cam disc 29 Stepping motor 30 lifter shaft 31 Lifter lever 32 Positioning Cam 33 Linear guide 34 Slide Block 35, 36 Z guide 37 Pressing bracket 38 Compression spring 39 Spring bush 40 Adjustment lever 41 (stroke level) cam disc 42 Stepping motor 43 Sensors 44 Spring guide G instantaneous position H Sine wave vibration stroke HA stroke amplitude HN Stroke Level NG1, NG1', NG2, NG3 workpieces OT Top Dead Center UT bottom dead center

Claims

1. - a throat plate (3a), a workpiece presser foot (13) designed to perform a stroke movement to press a workpiece (NG) on said throat plate (3a) during the sewing procedure; - a driven stroke amplitude adjusting device (17) for setting the stroke amplitude (HA=X, HA=Y) of the stroke movement of the workpiece presser foot (13) between the top dead center (A, C, E) and the bottom dead center (B, D, F); a driven stroke level adjustment device (18) for setting the stroke level (HN) of the stroke movement of the workpiece presser foot (13) relative to the throat plate (3a); a control / regulation device (11) in signal communication with said stroke amplitude adjustment device (17) and said stroke level adjustment device (18); A sewing machine (2) having the same.

2. 2. The sewing machine according to claim 1, further comprising a sensor (43) for detecting the actual stroke position of said workpiece presser foot (13) on said stitch plate (3a).

3. 3. The sewing machine according to claim 1, further comprising a mount for the workpiece presser foot (13), the workpiece presser foot (13) being preloaded into its mounting position by a spring (38) in the mount.

4. 4. A sewing machine according to claim 3, characterized in that it comprises a setting device for setting the preload of the spring (38).

5. A sewing unit (1) comprising a sewing machine (2) according to any one of claims 1 to 4.

6. 5. A method of operating a sewing machine according to any one of claims 1 to 4, comprising the steps of: - specifying a stroke amplitude (HA) by means of said stroke amplitude adjustment device (17); - Target stroke level (HN Ｓｏｌｌ ) specifying - the actual stroke level (HN) that occurs for the specified stroke amplitude (HA) Ｉｓｔ ) detecting - the actual stroke level (HN Ｉｓｔ ) and the target stroke level (HN Ｓｏｌｌ and adjusting said stroke level adjustment device (18) until the difference between said stroke level adjustment device (18) and said stroke level adjustment device (18) is within a predetermined acceptable limit.

7. 5. A method of operating a sewing machine according to any one of claims 1 to 4, comprising the steps of: - specifying a stroke level (HN) by means of said stroke level adjustment device (18); - target stroke amplitude (HA Ｓｏｌｌ ) specifying - the actual stroke amplitude (HA) that occurs for the specified stroke level (HN) Ｉｓｔ ) detecting - the actual stroke amplitude (HN Ｉｓｔ ) and the target stroke amplitude (HN Ｓｏｌｌ and adjusting the stroke amplitude adjustment device (17) until the difference between the stroke amplitude and the stroke amplitude is within a predetermined tolerance limit.

8. 5. A method of operating a sewing machine according to any one of claims 1 to 4, comprising the steps of: - specifying a first stroke level (HN1) by means of said stroke level adjustment device (18); - specifying a stroke amplitude (HA) by means of said stroke amplitude adjustment device (17); - operating said sewing machine (2) along a first sewing path at said first stroke level (HN1) and stroke amplitude (HA); - specifying a further stroke level (HN2) different from the first stroke level (HN1) by means of said stroke level adjustment device (18); - operating said sewing machine (2) along a further stitching path at said further stroke level (HN2) and said stroke amplitude (HA).

9. A method of operating a sewing machine (2) according to any one of claims 1 to 4, comprising the steps of: - specifying a first stroke level (HN1) by means of said stroke level adjustment device (18); - specifying a first stroke amplitude (HA=Y) by means of said stroke amplitude adjustment device (17); - operating the sewing machine (2) along a first sewing path at said first stroke level (HN1) and said first stroke amplitude (Y); - specifying a further stroke level (HN2) different from the first stroke level (HN1) by means of said stroke level adjustment device (18); - specifying by means of the stroke amplitude adjusting device (17) a further stroke amplitude (HA=X) different from the first stroke amplitude (Y), the specification of the further stroke level (HN2) and / or the further stroke amplitude (X) being performed in such a way that the stroke position of the bottom dead center (B, F) of the workpiece presser foot (13) remains constant within predetermined tolerance limits, independently of the specified stroke amplitude (Y, X); - operating the sewing machine (2) along a further stitching path at said further stroke level (HN2) and said further stroke amplitude (X); A method comprising:

10. A method of operating a sewing machine (2) according to any one of claims 1 to 4, comprising the steps of: - specifying at least one stroke level (HN) by means of said stroke level adjustment device (18); - specifying at least one stroke amplitude (HA) by means of said stroke amplitude adjustment device (17); - operating said sewing machine (2) along at least one stitching path at said at least one stroke level (HN) and said at least one stroke amplitude (HA); - after actuation, lifting the workpiece presser foot (13) by means of the stroke level adjustment device (18) and removing the workpiece.

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