JP2007007391A - Sewing machine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sewing machine, improved to automatically switch the sewing machine to the thickness of cloth. <P>SOLUTION: This sewing machine includes: a housing having a base plate; a top arm; and a strut for integrating the base plate with the top arm. A metallic presser presses a cloth piece near a stitch forming position. The metallic presser driven by a movable rod is capable of moving between the lift position for releasing the cloth piece and the pressing position for the cloth piece to be pressed. When the metallic presser moves between these positions, the distance of at least one movable rod part from a reference structure fixed to the housing stably changes. The position sensor detects the position of the metallic presser in the pressing position. A control system makes signal connection thereto. The system sets an adjustment variable for the sewing machine depending upon the output value of the position sensor. As a result, the obtained sewing machine automatically performs switching to the thickness of variable cloth piece. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The invention relates to a sewing machine according to the so-called preamble part of claim 1.

  A general type sewing machine is known, for example, from US Pat. As soon as there is some change in the fabric to be sewn with this type of sewing machine, the sewing machine must be readjusted manually or the sewing machine must be programmed, which is time consuming.

DE3043141A1

  The object of the present invention is to improve a sewing machine of the type mentioned at the outset so that the sewing machine is automatically switched with respect to the thickness of the fabric.

  According to the invention, this object is achieved by a sewing machine having the features of claim 1.

  The invention starts from the experience that the critical parameter relating to the thickness of the workpiece is the thickness of the fabric that is compressed during the sewing operation. The compressed thickness of the fabric is measured by the hold-down foot press position detected by the position sensor. It is based on the position of the rod assembly that represents that position of the presser foot. The presser foot is a presser foot that keeps the fabric in the vicinity of the stitch formation position, or a feeder foot that keeps the fabric in the press position while the fabric is being fed. Thus, the automatically detected compressed fabric thickness in the vicinity of the stitch formation position is converted into a given adjustment variable by the control system depending on the compressed fabric thickness. The sewing machine automatically adapts to the detected compressed fabric thickness. There is no need for manual readjustment or manual program conversion. This reduces the set time when switching workpieces. Furthermore, incorrect adjustments are avoided. Using the adjustment variables provided by the control system, a safe dough supply is obtained with the presser foot, ie the minimum pressure applied to the dough by the presser and / or feeder.

  A position sensor according to claim 2 provides an easy distance measurement. Alternatively, the position of certain parts of the locally movable rod assembly can be determined without the need for relative distance measurements.

  A sensor of the type according to claim 3 or 4 takes into account the sensor itself for distance measurement.

  The position sensor according to claim 5 is elegantly integrated into the rod assembly. Such a position sensor device takes into account that in known sewing machines, the pressure at which the pressing part acts on the housing part depends on the height of the presser foot at the pressing position, i.e. on the compressed fabric thickness. ing.

  The light sensor according to claim 6 is embodied as a distance sensor or a sensor that locally determines the absolute position of the part, for example a light barrier or a light curtain.

  With the control system according to claim 7, the sewing speed of the sewing machine can be adapted to the compressed fabric thickness. The sewing speed is kept relatively close to the maximum possible sewing speed for certain fabric thicknesses that reduce the total sewing time.

  The control system according to claim 8 allows the thread tension to be optimally adapted to the respective workpiece thickness and ensures proper stitch formation even when the material thickness is increased.

  The control system according to claim 9 ensures a safe feed at the same time with minimal feed lift. In particular, the minimum required lifting height is always ensured in this way, for example during ventilation of the lift cylinder applied in this context, saving time when operating the sewing machine and easily positioning the workpiece be able to.

  The control system according to claim 10 allows the stitch length to be optimally adapted to the fabric thickness.

  Details of the invention will become apparent from the following description of an embodiment in conjunction with the drawing.

  1-3 show the realistic reproducibility of the partially disassembled sewing machine 1 apart from the control components. 4 and 5 show a schematic view of the sewing machine 1 and show the connection of the mechanical parts of the top feeder device, indicated generally at 2. The basic design of the sewing machine 1 is similar, so only the substantially important parts of the present invention will be described below.

  The sewing machine 1 has a C-shaped housing 3. It has a base plate 4 and a top arm 5. In order to complete the C shape, the column (standard) 6 connects the base plate 4 and the top arm 5. The arm shaft 7 is accommodated in the arm 5 (see FIG. 4) and is driven by a motor (not shown). The vertical movement of the needle bar 8 having the sewing needle 9 and the movement of the top feeder device 2 are caused by the rotation of the arm shaft 7 by mechanical connection. Due to the operation of the top feeder device 2, its kinematic design is clearly seen in FIGS. 4 and 5, and the arm shaft 7 is coupled to the eccentric disc 10 so as not to rotate. A connecting rod 11 is coupled to the eccentric disk 10, and the rod 11 is coupled to the link 12. The link 12 rotates around an axis parallel to the arm shaft 7 by a link joint 13 fixed to the housing. The link 12 is connected to another connecting rod 14 by the opposite end of the connecting rod 11. The rod 14 comprises a permanent magnet 15, which creates a magnetic field with magnetic field lines extending substantially perpendicular to the base plate 4.

  FIG. 4 shows the top feeder device 2 in the position of pressing a piece of thick fabric 16 to be sewn. Hereinafter, it is referred to as a first presser position. In the first presser position, a Hall sensor 17 is in the vicinity of the permanent magnet 15. The sensor 17 is provided on an extension arm 18 fixed to the housing. The hall sensor 17 is connected to the central control system 20 via the signal line 19.

  The connecting rod 14 having the magnet 15 is connected to the upper corner of the triangular lever 21 in FIG. 4 by the opposite end of the link 12. The lower left corner of the triangular lever 21 is connected to the presser 22. The presser 22 functions to press the fabric near the stitch formation position. A compression spring 24 is held between the lower left joint of the triangular lever 21 and the upper housing cover 23 in FIG. 4, and its pre-load is adjusted by a spring load set screw 25. The spring load set screw 25 is driven by a motor. This drive mechanism is connected to the control system 20 via a signal line 26. The lifting height is adjusted by a spring-loaded set screw 25 as an adjustment member that drives the motor. The lower right corner joint of the triangular lever 21 in FIG. 4 is connected via a connecting rod 27 to a feeder 28 for the fabric to be sewn.

  The top feeder device 2 is a movable rod assembly for movement by the operation of the presser 22 and the feeding device 28. In operation, the presser foot 22 and the feed device 28 contribute to the release of the dough for its top feed by alternating elevation from the presser position to the lifted position. In the sewing machine 1, the lift positions of the presser foot 22 and the feeding device 28 are set by motor drive adjustment wheels 29. The adjusting wheel 29 is connected to the control system 20 via a signal line 30.

  In the sewing machine 1, the thread tension of the first sewing thread is adjusted by the motor drive adjusting member 31. This is connected to the control system 20 via a signal line 32. In the sewing machine 1, the thread tension of the second sewing thread is adjusted by the motor drive adjusting member 33. This is connected to the control system 20 via a signal line 34.

  In the sewing machine 1, the stitch length is adjusted by a motor drive adjusting member in the shape of the stitch length adjusting wheel 35. This is connected to the control system 20 via a signal line 36.

  The control system 20 is connected to a motor control system 38 via a signal line 37. The motor control system 38 is in signal connection with the drive motor for the arm shaft 7 (not shown).

  Adjustment variables for the spring loaded set screw 25, lift adjustment wheel 29, thread tension adjustment members 31, 33, stitch length adjustment wheel 35 and motor control system 38 are set as follows.

  During the top feed, the presser 22 and the feed device 28 are alternately moved between the presser position and the raised position by the top feeder device 2. At the presser position, the positions of the presser 22 and the feeding device 28 depend on the thickness at which the fabric is compressed. The first press position according to FIGS. 1, 2 and 4 shows, for example, two layers of relatively thick fabric 16 which is hardly compressed.

  The second presser position seen in FIGS. 3 and 5 has, for example, a layer of relatively thin fabric 39 that is hardly compressed. Depending on the quality of the fabric, a relatively thick fabric is also compressed in the hold down position and thus has a relatively thin stitch forming area thickness. For the sewing operation, how thick the fabric is when pressed by the presser 22 and the feeding device 28 is critical.

  The connecting rod 14 is a movable part of the top feeder device 2, and the distance from the extension arm 18 continuously changes between the raised position and the presser position when the presser 22 and the feeding device 28 are moved. For example, in a relatively thick fabric even when compressed in the first presser position, the permanent magnet 15 is in the immediate vicinity of the Hall sensor 17. Via the signal line 19, the Hall sensor 17 sends a signal to the corresponding control system 20 very close to the permanent magnet 15. The control system 20 then calculates or stores the set values for the spring load of the compression spring 24, the position of the presser 22 and the feeder 28 when raised, the thread tension, the stitch length and the sewing speed. Read them from the configured settings table. Next, these set values are set by the control system 20 via the signal lines 26, 30, 32, 34, 36 and 37, the spring load set screw 25, the lift adjusting wheel 29, the thread tension adjusting member 31 and the thread tension adjusting member 33. , To the stitch length adjusting wheel 35 and the motor control system 38.

  The permanent magnet 15 has a large distance from the Hall sensor 17 which produces a sensor signal corresponding to a thin compressed fabric thickness, with a fabric that is relatively easily compressible in the presser position or an inherently thin fabric.

  The closer the approach from the permanent magnet 15 to the Hall sensor 17 is, the thicker the compressed workpiece is, the higher the yarn tension adjusted by the yarn tension adjusting members 31, 33, for example.

  The thicker the cloth measured by the Hall sensor 17, the higher the positions of the presser 22 and the feeding device 28 that are set, and the safe feeding of the top feeder device 2 is guaranteed.

  The greater the measured thickness of the compressed fabric, the lower the speed of the arm shaft 7 set by the motor control 38, ensuring a safe feed and reliable sewing.

  The thicker the compressed fabric, the greater the loss of stitch length while sewing. Correspondingly, the stitch length in the case of thick compressed fabric increases with the corresponding value set by the stitch length adjusting wheel.

  Furthermore, the lifting height matches the predetermined fabric thickness. The lifting height of the presser 22 and the lifting height of the feeding device 28 can be selected so that the dough can be inserted and removed as appropriate. Therefore, when the lift cylinder as part of the top feeder device 2 is ventilated, the minimum lift height necessary to save time is selected. Furthermore, the fabric is easily positioned.

  As a result of the change in the distance between the extension arm 18 and the connecting rod 14, the distance between the hall sensor 17 and the permanent magnet 15 also changes periodically when the top feeder device 2 is operated. Whenever the presser 22 together with the feed device 28 is in the presser position, the distance between the Hall sensor 17 and the permanent magnet reaches an extreme value. This extreme value is determined by time-resolved detection of the corresponding output value of the Hall sensor 17 by the control system 20. The extreme values are clearly assigned to the presser positions of the presser 22 and the feeding device 28. It forms a dimensional figure for the thickness of the dough 16 or 39 which is compressed by the presser 22 and the feeder 28.

  Instead, the position sensor formed by the Hall sensor 17 together with the permanent magnet 15 in the embodiment described in FIGS. 1 to 5 is embodied by another type of sensor. For example, the position sensor is a capacitive proximity sensor, the extension arm 18 and the connecting rod 14 are part of a capacitor, and the capacitance is measured. The position sensor is a piezoelectric element arranged between a part (for example, a compression spring 24) thrust-connected to the presser 22 (for example, a compression spring 24) and a part of the sewing machine 1 (for example, the housing cover 23) fixed to the housing. . The piezoelectric element measures the pressure acting on the presser 22 or feed device 28 where the compression spring 24 is in the presser position. This pressure depends on how much the presser 22 or the feeder 28 in the presser position is lifted by the corresponding thick fabric underneath. In another embodiment, the position sensor is a light sensor, such as a light curtain.

  The application of the adjustment variable to the fabric thickness measured by the Hall sensor 17 is made without delay, especially because of the compressed fabric thickness that changes continuously during the sewing operation.

  As described above, the position detection for measuring the thickness of the compressed fabric has been described with reference to the presser 22 that holds the fabric. It is also possible to perform this measurement using the feeding device 28 in the cloth presser position.

  As far as the motor drive mechanism of the machine part is mentioned above, this is for example a pneumatic drive, a hydraulic drive or a stepper motor drive.

1 is a perspective view of a sewing machine with a control system schematically shown with some of the elements of the housing removed. FIG. FIG. 3 is a partially open front view of a sewing machine having a presser in a presser position on a thick fabric with the front cover removed and inserted. FIG. 3 is a view similar to FIG. 2 of a sewing machine having a presser in a presser position on an inserted thin fabric. It is the schematic of the top feeder apparatus of the position corresponding to it of FIG. FIG. 5 is a view similar to FIG. 4 of the sewing machine at the position of the corresponding top feeder device in FIG. 3.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Sewing machine 2 Top feeder apparatus 3 Housing 4 Base plate 5 Top arm 6 Strut 7 Arm shaft 8 Needle bar 9 Sewing needle 10 Eccentric disk 11 Connection rod 12 Link 13 Link joint 14 Connection rod 15 Permanent magnet 16 Material 17 Hall sensor 18 Extension arm 19 Signal line 20 Control system 21 Triangular lever 22 Presser 23 Upper housing cover 24 Compression spring 25 Spring load set screw 26 Signal line 27 Connecting rod 28 Feeder 29 Adjustment wheel 30 Signal line 31 Motor drive adjustment member 32 Signal line 33 Motor drive adjustment member 34 Signal line 35 Stitch length adjusting wheel 36 Signal line 37 Signal line 38 Motor control system

Claims (10)

Housing (3), base plate (4), top arm (5), strut (6) connecting base plate (4) and top arm (5), and at least one presser foot for pressing fabric (16, 39) 22, 28) sewing machine (1),
The presser foot (22, 28) can be moved by the movable rod assembly (2) between the lifted position for releasing the fabric (16, 39) and the presser position for pressing the fabric (16, 39).
At least one movable rod portion (14) of the movable rod assembly (2) is provided, and the distance from the reference structure (18) fixed to the housing (3) to the movable rod portion is set between the raised position and the pressing position. In sewing machines that change continuously between
A position sensor (17) is provided for detecting the position of the presser foot (22, 28) at the presser position,
A control system (20, 38) in signal connection (19) with the position sensor (17) is provided which sets an adjustment variable for the sewing machine (1) depending on the output value of the position sensor (17). Sewing machine.   2. The position sensor (17) according to claim 1, characterized in that a position sensor (17) is embodied for measuring the distance of the movable rod part (14) from the reference structure (18) fixed to the housing (3). sewing machine.   The sewing machine according to claim 2, characterized in that the position sensor (17) is a Hall sensor.   The sewing machine according to claim 2, wherein the position sensor (17) is a capacitive proximity sensor.   The position sensor (17) is a piezoelectric element arranged between the part (24) pushed and connected to the presser foot (22) and the part (23) of the sewing machine (1) fixed to the housing (3). The sewing machine according to claim 1, wherein:   The sewing machine according to claim 1 or 2, characterized in that the position sensor (17) is an optical sensor.   Control system (20, 38) embodied such that the speed of the arm shaft (7) is set as an adjustment variable for the operation of the sewing part or feed part (8, 9, 22, 28) of the sewing machine (1) The sewing machine according to any one of claims 1 to 6, wherein   8. The control system according to claim 1, characterized in that the set value of the tension of the yarn tensioning device (31, 33) is set as an adjustment variable. 9. sewing machine.   Sewing machine according to any one of the preceding claims, characterized in that the control system (20, 38) is embodied such that the raised position of the presser foot (22) is set as an adjustment variable.   10. Control system (20, 38) embodied such that the individual feed speeds of the stitch length adjusting device (35) of the feed device of the sewing machine (1) are set as adjustment variables. The sewing machine according to any one of the above.

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