EP0234397B1 - Numeric control of sewing machine operation - Google Patents

Description

The invention relates to a controller for driving the needle bar or needle bars and the sewing material transport or the sewing material transport on embroidery or quilting machines.

From the German patent 30 20 721 a speed control for the drive motor for the needle bar or needle bars on embroidery, quilting or sewing machines is known, in which the stitch lengths of several pending stitches are queried one after the other from an information carrier, stored serially and measured in cycles. Then the speed of the needle bar drive motor is adapted to the highest of the values measured in a series. The needle bar drive motor is designed as a three-phase motor, the speed of which is directly dependent on the frequency of a power supply, which in turn is controlled by the result of each cyclical measurement. The power supply for the needle bar drive motor is controlled by a frequency generated in a computer depending on the result of the cyclical measurement.

Also known is an embroidery, quilting or sewing machine, in which the upper thread and lower thread are linked by means of a hook or shuttle, while the needle is in the material, with a control of the stitch formation drives by means of a pattern information carrier, which has the required values for a contains sample good movement. With this known embroidery and quilting machine, the re-entry of the needle after it has left the material can be delayed as desired. The control generates the command to delay when the next following stitch length retrieved from the pattern information carrier exceeds a value that cannot be carried out for the good of a normal working cycle within the shift phase (German patent specification 32 06 731). The disadvantage of this known measure is the fact that the needle drive must be accelerated and decelerated constantly, although it represents the greater mass than that which is predetermined by the transport device for the sewing material.

Above all, however, the at least partially automated sewing process and the sewing device provided for it according to EU-OS 117 170 should be mentioned. The invention according to this prior publication is based on the following ideas and considerations: Works in the clothing industry, in the manufacture of hosiery and shoes, of leather articles, of upholstery products, in the area of articles for child care and even for furniture and decoration the staff with large series of completely identical operations using machines for sewing or piercing. This is particularly true in clothing manufacturing, where tasks are spread across a variety of work stations, each with one worker performing the same process. In each of these operations there is a section that requires special attention from the user of the machine, such as a seam end, a change of direction, or the creation of a collar end, which is a very significant nervous effort. The search for a relief from this effort has automated these repetitive processes. This previously known invention therefore relates to a method for at least partially automating a seam production, which is carried out by means of a sewing machine, which has a speed control by means of a step-by-step element and which is equipped with a timer, a sensor for the position of the seam speed control element and a sensor which interacts with a fabric, according to which one first carries out a recording phase of the independent sewing, in order to subsequently produce the seam in a repetitive manner . The sensor that interacts with the fabric is a seam length sensor that is used to measure the length of the fabric passing under the needle. The recording phase, after generally activating the timer, the seam speed control position transmitter and the seam length transmitter, includes storing the instantaneous value of each of these three parameters with each user controlled change in the position of the speed control element, whereas the playback phase consists of continuously recording the time and to record the distance of the seam after a general activation of the sensors. To control the position of the speed control element, the elapsed time is gradually compared with the stored time when the determined position of the speed control element is a zero speed position by reading its stored value, and the seam distance is compared with the stored seam distance when the detected position of the speed control is a non-zero speed position. The activation of the three sensors mentioned is controlled at the same time as the lowering of the machine's needle lifter. In simple terms, in other words, it is a question of recording and saving individual work processes within a clothing factory in the course of work preparation, and of allocating the stored work processes to the individual seamstresses. Here, an X-fold repeating sewing process is recorded and saved as part of a ready-made clothing shop and then made available to the seamstresses to make their work easier.

Finally, it should be mentioned in relation to the prior art that sewing machines are known, both for domestic use and for industrial use, which have a sewing head with thread tensioner, a presser foot, a lower thread roller with a gripper for guiding the lower thread and transport devices for further transport of the sewing material and optionally have additional sewing aids (DE-OS 32 22 716). The individual elements have separate drives that can be controlled synchronously by a control device. The control device can be constructed on a hydraulic basis or on an electronic basis. The aim of this measure is to separate the individual elements such as the sewing head, bobbin thread, looper and transport devices from the other elements, and to position them largely flexibly so that each sewing workstation is optimally equipped in accordance with the respective sewing tasks can be, ie there should not be any impairments caused by systems that are not required for the special sewing work station and sewing operation.

The present invention is based on the prior art discussed at the outset and aims to simplify control on the one hand and, above all, to even out the running of the machine, in order to achieve a higher working speed in this way. According to the invention, this object is achieved by those measures which are the content and subject of claim 1. This ensures that the needle in the subject matter of the invention runs at a predetermined, selectable speed, whereas the sewing material transport is tracked depending on the length of the respective components of the lockstitch, so as to make the running of the machine as uniform as possible and at the same time maximize the working speed achieve.

• Fig. 1 ein Blockschaltbild der Steuerung;
• Fig. 2 eine drei Stiche umfassende Stichfolge und die
• Fig. 3, 4 und 5 Weg-Zeit-Diagramme und zwar für die Nadel und für die X- und Y-Komponenten der Stiche nach der Stichfolge gemäß Fig. 2.

The invention is explained in more detail with reference to the drawing in connection with the control for a quilting machine. Show it:

• Fig. 1 is a block diagram of the controller;
• Fig. 2 is a three-stitch sequence and
• 3, 4 and 5 path-time diagrams for the needle and for the X and Y components of the stitches according to the sequence shown in FIG. 2.

The quilting machine, which is not shown in detail here, has a needle drive and a drive for the path components X and Y of the sewing material. The construction of the quilting machine corresponds to the conventional design. For driving the needles a drive motor M _{N is} provided, the speed of which is entered manually via a controller P depending on the respective sewing or step program. Two further drive motors M _X and M _Y serve to move the sewing material, one drive motor M _X for the forward and backward movement (X component) of the sewing material and the other drive motor M _Y for the lateral back and forth movement (Y -Component). Frequency-controlled asynchronous machines, field-regulated DC machines, stepper motors or pulse-controlled synchronous motors are suitable as drive motors. In the exemplary embodiment described above, it is assumed that AC drive machines are used here, the speed of which is directly dependent on the frequency of the supply voltage, which in turn is influenced by the control device. Such frequency controls are known and are offered on the market.

Each of the three drive motors M _N , M _X , M _Y is connected to a pulse generator G _N , G _X , G _Y , which feed their pulses to a computer CR during operational use, the number of pulses counting from a certain point in time corresponding adjustment path of the motors M _X , M _Y corresponds, or a predetermined period of time during which the needle travels a predetermined distance. The computer receives the comparison values necessary for it via an information carrier containing the step program, for example a punched tape or a magnetic tape, the respective program values of which are read by a reader L to the computer CR. The control variables determined by the computer are then partially fed in comparison with the counting pulses of the drive motor to the control elements RM _Y and RM _X , which in turn act on the drive motors M _X and M _Y assigned to them in the sense of a speed increase or speed reduction.

Fig. 2 illustrates a three stitches S₁, S₂, S₃ comprehensive sequence. The position O 'is selected as the starting position and the end position of the sequence corresponds to point C. The path components S _xn and S _yn assigned to the individual stitches S _n can be seen directly from the diagram in FIG. You can choose a positive value (moving forward) or a negative value (moving backwards) exhibit. Depending on the length of a stitch S _n and its position within the right-angled coordinate system XY, these path components are very different, both in terms of their size and their direction.

, die Summe dieser beiden Zeitspannen t_a und t_i entsprechen der Periode T. Die Zeitspanne t_a, während der die Nadel außerhalb des Nähgutes liegt und während der das Nähgut gegenüber der Nadel verschiebbar ist, ist also nur halb so lang wie jene Zeitspanne t_i, während der die Fäden verschlungen werden.The diagram of Fig. 3 illustrates the course of the needle N and it should be noted here that the drive motor M _N rotates at a constant speed depending on the step program to be carried out, so that the movement of the needle over time t shows a sinusoidal course and The time period T during which the needle makes a complete movement is referred to as the period. The speed of the motor M _N for the needle drive is set manually via a controller P and depends on the type of program to be carried out. In the time-distance diagram according to FIG. 3, line E illustrates the level of the sewing material and it can be seen from the position of this line E in the diagram that the time period t _a during which the needle is outside the sewing material is considerably less than the period of time t _i during which the needle is inserted into the sewing material and during which the actual stitch is formed, during which the upper and lower threads are intertwined, the means used for this purpose being known boats or grippers. The ratio of these two periods ${\text{t}}_{\text{a}}{\text{: t}}_{\text{i}}\text{= about 1: 2}$

, the sum of these two time periods t _a and t _i corresponds to the period T. The time period t _a during which the needle lies outside the sewing material and during which the sewing material can be displaced relative to the needle is only half as long as that time period t _i , during which the threads are entwined.

The two time-distance diagrams according to FIGS. 4 and 5 assigned to the time-path diagram according to FIG. 3 illustrate the stitch components S _xn and S _yn .

If the first stitch S 1 is considered, which extends from O '- A (FIG. 2) and which has only one path component, namely the path component S _x1 , it can be seen from the diagrams associated with one another according to FIGS. 3 to 5 that during the first period t _a , 3, the sewing material must have traveled the path S _x1 in the X direction, whereas no movement is carried out in the Y direction. The same applies to the following stitches S₂ and S₃ or the path components assigned to these stitches. However, these stitches S₂ and S₃ are preceded by movements in both the X and Y directions. The time period available for the respective displacement movement in both the X and Y directions is always t _a , this is the time during which the needle, which is driven at a constant speed, lies outside the material to be sewn. Since - as already mentioned - the needle drive is constant, the time period t _a available for the respective displacement movement in both the X and Y directions is constant. However, since the distances to be covered during this constant time span are very different (see S _xn and S _yn in _FIGS . 2, 4 and 5), the speed of the adjustment of the sewing material, which is effected by the motors M _X and M _Y , is per Stitch very different. The angles α and β in the diagrams according to FIGS. 4 and 5 represent a measure of the respective speed at which this adjustment must be carried out.

So that the drive motors M _X and M _{Y can} travel the necessary distance depending on the position and length of the respective stitch during the time t _a available for the adjustment of the sewing material, they have to track the needle movement continuously. For this purpose, the time period t _a during which the needle is outside the sewing material corresponds to a pulse sequence of, for example, a hundred pulses. Each stitch component S _xn or S _yn is also assigned a pulse sequence, the number of which is proportional to the length of the respective path, for example the stitch component S _x1 is assumed here as a unit length, with a pulse sequence of one hundred pulses. During the first period of time t _a (O '- A), a hundred pulses thus arrive at the computer CR from the pulse generator G _{N of} the needle drive motor M _N. During this time, the information carrier, via the reader L, gives the computer CR a hundred pulses for the path component S _x1 .

The adjustment path in the X direction actually forced by the motor M _X is determined by the number of pulses coming from the pulse generator G _X. At each point in time t _x during the period t _a (FIG. 3), the number of pulses I _N and I _X arriving in the computer CR must be the same, in which case it is guaranteed that at point in time A on the time line t according to FIG. 3, that is, when the needle sticks into the sewing material, the motor M _X has adjusted the sewing material by the amount S _x1 relative to the needle. If at any time t _{x there are} differences in the number of incoming pulses I _N and I _X , the controller RM _{x is} activated via the computer CR and the speed of the motor M _{X is} thereby dependent on whether the difference is positive or negative is reduced or increased, so that by the end of the time period t _a , that is when the time A is reached, the sewing material in the X direction has completely passed through the path S _x1 provided for the stitch S ₁ . The same applies to the stitch S₁ also for the subsequent stitches S₂ and S₃, with these stitches or the movement of the stitches provided for these stitches in the directions X and Y in the computer also processes the incoming pulses from the encoder G _Y. be, but in the manner described.

It is entirely possible to assign different pulse numbers to the time span t _a and the unit path length of a stitch, for example a hundred pulses for the time span t _a and two hundred pulses for the unit _path length S _x1 . The pulse quantities continuously summed and compared with one another during the time period t _a must correspond to one another at the end of the time period t _a , that is to say the point A on the time line according to the time-distance diagram according to FIG. 3, that is, at the time A hundred pulses from encoder G _N and two hundred pulses from encoder G _{X have} arrived in the computer.

It can be seen from the diagrams according to FIGS. 4 and 5 that, for example, the path component S _{y3 is} approximately 2.3 times larger than the component S _x1 assumed here as the unit path _length , that _{This means} that the pulse sequence assigned to the path component S _y3 must therefore be 2.3 times larger than that of the standard path length, which is two hundred and thirty pulses here. The motor M _Y must therefore deliver two hundred and thirty pulses via its pulse generator G _Y to the computer CR during the time t _a given to it for this distance, which is given to it by the step program that is input via the reader L. At time t _y (see FIG. 3), when the needle has traveled half of its path outside the material to be sewn, fifty impulses having arrived at the computer CR via the pulse generator G _{N associated} with its drive motor M _N , the transmitter G _{Y of} the drive motor M _{Y a} hundred and fifteen pulses have arrived, which are specified by the step program. However, if there is a difference between the actually received number of pulses and the number of _pulses specified by the information carrier for the path S _y3 , the speed of the drive motor M _{Y is} increased or decreased via the controller RM _Y , so that it is ensured that at the end of the period t _a the material has covered the path component S _y3 . The X component S _x3 assigned to the stitch S ₃ is considerably shorter than the Y component, so that the material can be moved more slowly at the same time in the X direction. The difference in speeds results from the comparison of the angles α '' and β '', which represent a measure of the adjustment speed.

In this way it is possible to drive the needle drive, which has a large mass, at a constant speed and to accelerate and decelerate the sewing material carrier or the sewing material transport device, which has a much lower mass compared to the needle drive, in accordance with the path lengths to be traveled, as a result of which the movement of the sewing material is optimally adaptable to the highest possible sewing speed. This highest possible sewing speed is determined from the type of quilting or sewing program and is set manually via the speed controller P for the drive motor M _{N of} the needle drive.

The control according to the invention is advantageously provided in new embroidery, quilting or sewing machines. However, it is entirely possible to design this control as a kit with which existing machines of this type can be retrofitted and equipped in order to design them for a higher working capacity.

If there is talk of constant time spans above, for example the time span t _a during which the needle lies outside the material to be sewn, this applies to a specific pattern which is currently to be produced on the embroidery, quilting or sewing machine. Depending on the size and design of the pattern and / or depending on the materials that are processed on the machine, this time period t _a can change, since the speed of the needle movement on the respective pattern to be manufactured or on the respective one is to be adapted to the materials to be processed, as has already been mentioned above.

The invention has been defined and explained with reference to the periods mentioned. In principle, it is possible to use distances as definition variables instead of time spans, because these two physical quantities are linearly dependent on each other as a conversion factor via the respective speed.

In the exemplary embodiment described, a ratio of 1: 2 was specified for the two time periods t _a and t _i . The invention can also be used successfully in machines in which this ratio is a different numerical value, for example 1: 3.

Claims (5)

1. Control system for the drive of the needle bar or needle bars and of the transport device or devices for the material to be sewn on embroidery or quilting machines, in which separate motors are provided for the needle bar and the transport device for the material to be sewn respectively, in which the control system incorporates impulse transmitters and storage units and the impulse transmitters (G_N, G_X, G_Y) are linked to the drive motors (M_N, M_X, M_Y) both for the needle bar and for the transport device for the material to be sewn and the pulses (I_N) from the impulse transmitter (G_N) of the needle bar drive motor (M_N), which occur between the emergence of the sewing needle from and its reinsertion into the material to be sewn, are added together in a computer (CR), that a sequence of impulses in proportion to the particular length of the stitch is allocated to each stitch to be performed or its directional components (X, Y) and this sequence of impulses, which is input into the computer (CR) by a reader (L) from an information carrier containing the sewing program, or its instantaneous total is compared with the number of impulses supplied by the impulse transmitter (G_X, G_Y) of the drive motor (M_X, M_Y) or drive motors of the transport device for the material to be sewn and with the number of impulses supplied by the impulse transmitter (G_N) of the drive motor (M_N) of the needle bar and, in the event of differences, the computer (CR) activates one or more regulators (RM_X, RM_Y), which increase or reduce the rotational speed of the drive motor (M_X, M_Y) or drive motors for the transport device for the material to be sewn, with the result that at the end of the constant time interval (t_a) the number of impulses supplied by the impulse transmitter (G_N) of the needle drive (M_N) and allocated to this time interval (t_a) corresponds with the number of impulses supplied by the impulse transmitter (G_X, G_Y) of the transport device for the material to be sewn and allocated to the length of the next stitch (S_n) to be performed.
2. Control system in accordance with claim 1, characterised by the fact that the transport device for the material to be sewn incorporates a separate drive (M_X, M_Y) for each component (X, Y) of the movement in a manner already known per se, and an impulse transmitter (G_X, G_Y) is allocated to each of these drives.
3. Control system in accordance with one of claims 1 or 2 characterised by the fact that frequency-regulated alternating-current or three-phase-current motors (M_X, M_Y) are provided for driving the needle or for driving the transport device for the material to be sewn.
4. Control system in accordance with one of claims 1 or 2, characterised by the fact that impulse-regulated stepping motors (M_X, M_Y) are provided for driving the needle or for driving the transport device for the material to be sewn in a manner already known per se.
5. Control system in accordance with one of claims 1 or 2, characterised by the fact that field-regulated direct-current motors (M_X, M_Y) are provided for driving the needle or for driving the transport device for the material to be sewn.

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