JP2001353389A - Sewing machine depending on revolution number to correct stitches - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sewing machine capable of correcting the change in the length of a stitch depending on the number of revolutions. SOLUTION: This sewing machine is provided with a pulse generator 13 detecting the number of revolutions and the angular position of a sewing machine shaft 12 to generate pulses and an arithmetic and logic unit controlling the setting of a stitch regulating device 7 through a regulating means 9, and the stitch regulating device corrects the length of a stitch to the preset stitch length on the basis of an operation result according to the number of revolutions of the sewing machine. Moreover, the correcting method is filing a corrected value depending on the number of revolutions in a data memory 18 in the form of a table and allowing the value to be read by the arithmetic and logic device 15.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to at least one feed means, a stitch adjusting device, an adjusting device for a stitch adjusting device, and a pulse for generating a pulse by detecting a rotation speed and an angular position of a sewing machine shaft. The present invention relates to a sewing machine including a generator and an arithmetic unit that controls settings of a stitch adjusting device via an adjusting unit.

[0002]

2. Description of the Related Art According to DE 32 16 993 C3 (U.S. Pat. No. 4,495,877), which is the basis of the generic concept of claim 1, machining is performed to improve the positioning accuracy of the needle at the end point of the seam. It is known to detect the difference between the target feed amount of the feed means and the actual feed amount by using a detection device that responds to the passage of an edge of an object, and to consider the difference when calculating the set value of the stitch adjustment device. I have. Such a sensing device having at least two sensors arranged at a distance from each other is not only complicated in construction, but also for sewing curved edges of a workpiece, for example, in sewing shirts. In this case, the detection process is inaccurate due to the rotating motion of the processing unit, and the accuracy of the measurement result is reduced.

[0003] The main cause of the error seen between the set feed amount of the workpiece and the actual feed amount is the feed amount of the workpiece in one stitch forming process as the rotation speed of the sewing machine increases. It has been clarified that the stitch length is gradually increased as a result, and as a result, the stitch length is gradually increased.

To take this feed behavior into account, in the sewing machine known from US Pat. No. 4,548,143, the number of remaining stitches is dependent on the number of revolutions of the sewing machine at the time when the edge of the workpiece is detected. Is calculated. This measure is intended to ensure that changes in the stitch length depending on the rotational speed do not make the measurement results inaccurate. However, such a method of compensating for stitch length changes depending on the number of revolutions is a method for controlling a predetermined end point of one stitch, and the stitch length part amount is set when the last stitch. It is only applicable to those methods that are only considered.

German Patent No. 3617204C
Japanese Patent Application Publication No. JP-A-2005-11564 discloses an apparatus for measuring an actual feed length of a cloth feed. This type of measuring device and the attached signal processing device are relatively complicated in construction, and disturbances such as vibrations may not only deteriorate the accuracy of the measurement result, but also form the last stitch. In principle, the actual stitch length is measured when the rotation speed is much higher than the actual stitch length and the deviation between the target value and the actual value of the stitch length is much larger than the last stitch formation. A length shift occurs.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to provide a sewing machine capable of correcting a change in stitch length depending on the number of revolutions.

[0007]

In order to solve this problem, the present invention is characterized in that a stitch adjusting device can be loaded with a correction value depending on the number of revolutions.

[0008] The present invention is directed substantially to high rotational speeds.
Change the effective stitch length with respect to the set stitch length,
This is based on the idea that the set value of the stitch adjustment device is directly corrected by appropriately modifying the set value. Thus, no change in stitch length occurs, and therefore no additional measures need to be made to correct for the change in stitch length again. This provides accurate results in all stitch sections where stitch counting is performed.

According to a second aspect of the present invention, in the case of a sewing machine having a device for controlling a predetermined end point of a stitch at an interval from an edge of a workpiece, when sewing the remaining stitches after edge detection, it depends on the number of rotations. By compensating for stitch length variations according to the invention, particularly strong disturbances are eliminated. In this way, the actual stitch length of the remaining seam stitches will be very close to the calculated stitch length, thereby achieving relatively accurate needle positioning at the seam end point.

By taking into account the correction values which depend on the rotational speed, in particular in connection with the measure according to claim 3, ie the correction values which depend on the rotational speed are filed in a data memory in the form of a table and are processed by the arithmetic unit. By the action of reading,
As soon as the rotational speed starts to change, it is possible to immediately introduce a suitable stitch length setting correction value for this. Accordingly, German Offenlegungsschrift 38049
Instead of reducing the speed to a lower value a few stitches before the end of the seam, as disclosed in US Pat.
As disclosed in US Pat. No. 5,037,098, it is possible to continuously reduce the rotational speed to zero, while ensuring that the actual lengths of all the remaining stitches correspond to the set stitch lengths. You.

By means of the measure according to claim 4, the adjustment characteristics of the generally non-linear stitch adjusting device are detected numerically and are taken into account together as a correction value for the stitch length, so that the accuracy of the stitch length control and the stitch length control are improved. The positioning accuracy at the seam end point is further improved.

[0012]

BRIEF DESCRIPTION OF THE DRAWINGS The invention will now be described with reference to an embodiment illustrated in the drawings. In the sewing machine 1, reference numeral 2 denotes a substrate, and reference numeral 3 denotes an arm (upper casing). A vertically movable needle bar 4 having a needle 5 is supported in the head of the arm 3. Needle 5 cooperates with a looper (not shown) in a known manner.

A feed 6 is arranged in the substrate 2. Feed 6 corresponds to German Patent No. 3216 mentioned at the outset.
Feed 25 in a sewing machine disclosed in Japanese Patent Application Publication No. 993C3
It corresponds to. Similarly, the drive of the feed 6 corresponds to the drive of the feed 25 of the above-mentioned publication, and has a stitch adjusting device 7 configured as a link-type stitch adjuster in this known sewing machine. The stitch adjusting device 7 has an adjusting shaft 8 attached thereto, and the adjusting shaft 8 corresponds to the adjusting shaft 42 in the known sewing machine. The adjusting shaft 8 is directly connected to a stepping motor 9 used as adjusting means.

In order to drive the sewing machine, a positioning motor 10 provided with a control unit 11 and disposed in the substrate 2 is used. The positioning motor 10 drives the drive shaft 12 for the feed 6 in a manner not particularly shown in detail. A pulse generator 13 is disposed on the positioning motor 10, and the pulse generator 13 is configured to detect an edge of a workpiece by a light-blocking sensor device.
(Lichtschranke) is used to detect the rotational speed of the sewing machine 1 and the angular position of the drive shaft 12 when a light beam of (Lichtschranke) passes.
In the drawing, only the sensor 14 arranged in the head of the arm 3 is illustrated in the light blocking type sensor device. Further, the pulse generator 13 is also used for performing a stitch count in a known manner by detecting that the drive shaft 12 has completely rotated.

The control device has an arithmetic unit 15. The arithmetic unit 15 includes a processor 16, an I / O element 17,
And at least one EPROM 18. The arithmetic unit 15 is connected to the operation panel 19.

The graph of FIG. 1 shows how the stitch length S (in mm) increases with an increase in the rotation speed n (rotation speed / minute) of the sewing machine when the setting of the stitch adjusting device 7 is unchanged. For example, when the stitch length S is from 2 mm in the lower rotation speed range of 1 rotation / minute to 500 rotations / minute, it is approximately 2.0 at n = 6000 rotations / minute.
This indicates that the length is increased up to 5 mm. This feed characteristic generally occurs in all sewing machines, but may vary depending on the type of sewing machine.

In order to compensate for the change in stitch length depending on the rotation speed, which is illustrated in the actual value curve Si, for each type of sewing machine and for any series of sewing machines, each stitch length S Correction value K1 required at each rotation speed n
Is detected by measurement. The corrected target value Ss must be obtained by changing the setting of the stitch adjusting device 7 based on the correction value KI. In this target value Ss, the stitch length St actually performed always corresponds to the set stitch length Se over the entire rotation speed range. This correction value K1 is filed in the EPROM 18 in a table format.

Further, for any series of sewing machines, the adjustment characteristic of the stitch adjustment device 7 independent of the rotation speed is detected by measurement. That is, the stitch length setting value of the stitch adjustment device 7 obtained when the adjustment angle step of the adjustment shaft 8 is constant is detected. This stitch length setting is generally non-linear, and may vary widely over a wide range, especially when the feed direction is changed. To correct this non-linearity, a correction value K2 is detected for each stitch length setting value. The setting of the stitch adjusting device 7 must be changed by the correction value K2 so that the change in the set stitch length S is the same if the angle setting of the adjusting shaft 8 is the same. That is, the change in the set stitch length S must be the same for each angle step that can be performed by the stepping motor 9. The correction value K2 that does not depend on the rotation speed is also filed in the EPROM 18 in the form of a table.

When the sewing machine 1 operates, the arithmetic unit 15
Correction value K1 assigned to set stitch length S
And the correction value K1 assigned to the actual rotation speed n
The stepping motor 9 reads the data from the PROM 18 and calculates a correction adjustment amount from these correction values. The stepping motor 9 adjusts the stitch adjustment device 7 based on the correction adjustment amount so that the stitching actually performed at any arbitrary rotation speed is performed. The length St corresponds to the set stitch length Se.

If the stitch length changes depending on the number of revolutions, by correcting this change, it is possible to always form each stitch having the same stitch length. Also, if the stitch count performed by the pulse generator 13 is used, very accurate stitch length control can always be performed even when the stitch length is long.

In particular, when forming one stitch end stitch, the needle 5 must be accurately punctured at a pre-calculated position, and the target value and the actual value of the workpiece feed amount must be compared in advance. There is no. In this way, the predetermined end point of one stitch can be controlled much more easily than in the case of the sewing machine described in DE 32 16 993 C3 mentioned at the outset. The accuracy is further improved. This is because the difference between the target value and the actual value of the feed amount is detected by correcting the change in the stitch length depending on the rotation speed and the adjustment characteristic of the stitch adjusting device 7. This is because no error occurs as in the case of the known sewing machine.

[Brief description of the drawings]

FIG. 1 is a graph showing a stitch length characteristic curve depending on a rotation speed.

FIG. 2 is a diagram illustrating a sewing machine illustrated together with a block circuit diagram of a control device.

[Explanation of symbols]

 5 Needle 6 Feed 7 Stitch adjustment device 9 Stepping motor (adjustment means) 12 Drive shaft (sewing machine shaft) 13 Pulse generator 14 Sensor 15 Operation device 18 Data memory

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Roter Brühl Germany DE 67731 Ottabach Egertalstrasse 31 (72) Inventor Edgar Butzen Germany DE 66849 Landstuhl Richard Wagner Strasse 6 ( 72) Inventor Karl Ludwig Manuel Germany Day 66849 Land Stur Linkstrasse 2F Term (Reference) 3B150 AA01 AA05 CE01 CE27 DE14 DE27 GD03 GD22 GD25 GF02 JA02 JA03 JA07 LA16 LA85 LA88 LB01 MA15 NA15 NB05 NC03 NC06 QA06

Claims (4)

[Claims] At least one feed means (6), a stitch adjusting device (7), an adjusting device (9) for the stitch adjusting device (7), and the rotational speed and angular position of the sewing machine shaft (12). A pulse generator (1) that detects
3) and a calculating device (15) for controlling the setting of the stitch adjusting device (7) via the adjusting means (9). A sewing machine characterized in that the sewing machine can be loaded. 2. A device for controlling a predetermined end point of a seam at a distance from an edge of a workpiece, said device comprising a sensor (14) disposed in front of a needle (5). (14) starts the process for positioning the needle (5) at the seam end point when the edge of the workpiece has passed, and the arithmetic unit (15) uses the needle (5) and the sensor (14).
2. The sewing machine according to claim 1, wherein the number of remaining stitches is detected depending on an interval of the sewing machine and an angular position of the sewing machine shaft detected at the time of detecting the edge. Stitch adjusting device with correction value dependent on rotation speed (7)
Wherein the load of the sewing machine is performed at least while forming the remaining stitches. 3. The correction value according to claim 1, wherein the correction value depending on the rotation speed is filed in a tabular form in a data memory and can be read out by an arithmetic unit. sewing machine. 4. The data memory (18), wherein the value of the adjustment characteristic of the stitch adjustment device (7) relating to the stitch length is:
4. A file according to claim 1, characterized in that a correction value dependent on the rotational speed and a value relating to said stitch length of an adjustment characteristic can be linked to one another in a computing device (15). The sewing machine according to any one of the above.