JPH0232391B2 - SHISHUNUIMISHINNOSOKUDOSEIGYOSOCHI - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention stores data regarding the amount of movement of an embroidery frame sequentially for each stitch on a floppy disk, etc.
In particular, regarding an embroidery sewing machine that forms stitches by moving an embroidery frame using a driving means such as a stepping motor based on movement amount data read out for each stitch,
The present invention relates to a speed control device for an embroidery sewing machine that controls the driving speed of a motor connected to a main shaft based on read movement amount data.

Conventionally, in embroidery sewing machines, while the needle is located above the fabric, the rotation angle θ0 of the main shaft that allows the needle to pass above the throat plate, as shown in Fig. 8, is determined by a constant number proportional to the amount of movement of the embroidery frame. Previously, the stepping motor was driven by generating drive pulses with a certain period, but in such devices, the period of the drive pulse is constant, so even if the sewing speed of the sewing machine changes, the stepping motor does not move. time does not change,
Therefore, when the amount of movement of the stepping motor increases, the needle may penetrate the fabric before the movement is completed and come off the specified position, forming an undesired stitch or causing the needle to penetrate the fabric. There were disadvantages such as the cloth moving while being pricked, causing damage to the cloth and breakage of the needle.

Therefore, if the sewing speed of the sewing machine is slowed down and the amount of movement of the stepping motor is small, the waiting time for the needle to penetrate the fabric after the movement of the embroidery frame is completed becomes longer, reducing sewing efficiency. There were flaws.

An object of the present invention is to eliminate the above-mentioned conventional drawbacks and improve sewing efficiency by controlling the driving speed of the sewing machine motor to increase in inverse proportion to the amount of movement of the embroidery frame.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. Reference numeral 1 denotes a table having a flat upper surface 1a;
A sewing machine 2 is placed on the upper surface 1a so that the bed surface 2a is located on the same plane, and the main shaft (not shown) of the sewing machine 2 moves the needle 3 up and down in conjunction with a motor M installed on the same axis. . The motor M is driven by a servo circuit system so that its driving speed can be controlled, as will be described later. Reference numeral 4 denotes a support frame, in which an embroidery frame 5 for holding a stretched cloth is removably supported. The embroidery frame 5 is operated in conjunction with a pair of stepping motors XSTM and YSTM arranged below the table 1, and moves on the upper surface 1a of the table 1 in the Y direction along the axial direction of the main shaft of the sewing machine and in the direction crossing the Y direction. It is possible to move in the composite direction with the direction.

Reference numeral 6 denotes a floppy disk reading means, which has an insertion portion 6a that allows a floppy disk FP (FIGS. 4 and 6) to be attached and removed, and reads data from the inserted floppy disk FP. Reference numeral 7 denotes an operation panel, which is equipped with key switches for reading data from the floppy disk FP, setting the sewing speed of the sewing machine, controlling movement of the support frame 5, and the like.

Next, the control circuit of the present invention will be explained.

As shown in Figure 4, this control circuit controls the data read from the floppy disk FP.
A digital processing system DS that performs digital calculations using a CPU (central processing unit), and a stepping motor XSTM based on the output signal from the digital processing system DS.
It consists of a stepping motor drive special circuit DR that drives the YSTM at a constant speed for a predetermined number of steps, and a servo drive system SB that drives the motor M by servo (analog) control.

The control operation of the CPU in the digital processing system will be explained based on the flowchart of FIG. 5. First, it is determined whether the needle 3 has reached the uppermost position. This determination is made based on a detection signal from a well-known rotation angle detection means, not shown, which is arranged in relation to the main shaft and machine frame of the sewing machine 2. When the needle reaches the highest position, the embroidery frame 5
The next movement amount data, that is, the movement amount data after the next needle drop XJ, YJ (J represents the number of the needle drop point) are read from the floppy disk FP and XJ
Compare the amount of movement between and YJ, and set the larger value as LJ as the movement amount parameter. Next, the embroidery frame is determined using two known constants a1 and a2: the amount of movement a1 (cm) of the embroidery frame 5 corresponding to one drive pulse in the stepping motors XSTM and YSTM, and the number a2 of drive pulses generated per second. Value ωJ = a1a2π/LJ that is inversely proportional to the movement parameter LJ of 5.
is calculated, and then the value of ωJ is stored in a latch register for output to a D/A (digital/analog converter) in synchronization with the timing when the needle 3 penetrates the cloth.

Next, the servo drive system SB will be explained. The servo drive system SB is represented by a block diagram in FIG. 4, and the letters in the block represent the transfer function represented by Laplace transform using the parameter S. V is a manually operable variable resistor, which has a transfer function G3<1, and is used to reduce and adjust the driving speed of the motor M. DF is a circuit for improving the start-up characteristics of motor M,
A differentiator circuit consisting of a resistor and a capacitor is used to configure the transfer function to be R1+SG2. A is a servo amplifier and has linear amplification characteristics with a transfer function G4>1. Motor M is a first-order delay response function
It has G5/(1+TS), and T is the time constant of the delay in rising. As is already well known, this is 1-
It represents a rise characteristic such as exp(-t/T) (t is time). In this way, the CPU
When inputting the output ωJ of
TS), and is configured so that this value is directly proportional to the drive speed νJ of the motor M.

In addition, ωJ = a1a2π/LJ, and so that the product of G1 + SG2 and 1/(1 + TS) is almost constant,
In other words, if it is ideally set so that the rise delay is completely eliminated, then G3 (G1
+SG2)・G4・G5/(1+TS) can be regarded as a constant, so from now on, for convenience, the driving speed of the motor M will be expressed as νJ=K/LJ using a predetermined proportionality constant K.

The present invention has the above configuration, and its operation will be explained next.

In Fig. 3, P1 to P7 indicate needle drop points,
It is assumed that the stitches progress in this numerical order.

First, at point P1, the movement amount data from P1 to P2 is
Since X1, Y1 and X1 > Y1, based on the flow shown in Fig. 5, L1 =
It is set to L1.

Now, when the needle 3 comes out of the cloth at point P1, the stepping motor is activated based on the movement amount data X1 and Y1.
XSTM and YSTM are driven to move the embroidery frame 3 in the X-Y combination direction from point P1 to point P2. At this time, since X1>Y1, the movement in the Y direction is completed in a shorter time than the movement in the X direction. After the movement in the Y direction is completed (A1 in Fig. 9), when the hand 3 reaches the uppermost position (corresponding to approximately the midpoint between P1 and P2 in Fig. 3), the next movement amount data is generated based on the flow in Fig. 5.
X2 and Y2 are read from the floppy disk FP, and since X2>Y2, L2=X2,
From this L2, ω2=a1a2π/L2 is calculated. The calculated value of ω2 is temporarily stored in a predetermined register and is not immediately input to the D/A. Then X
When the movement in the direction is completed (B1 in FIG. 9), the needle 3 is located directly above P2, but at this time the needle 3 has not yet penetrated the fabric. When time T1 elapses from B1, the needle 3 penetrates the cloth, and in connection with this, the value of ω2 is transferred to the output register to the D/A, so ω2 = a1a2π/L2 is set in the servo drive system SB. Therefore, the driving speed of motor M ν2 = K/L2
becomes. Next, when the needle 3 comes out of the cloth, the stepping motor is activated based on the movement amount data X2 and Y2.
XSTM and YSTM drive to move the embroidery frame 5 from point P2.
Move in the X-Y composite direction towards point P3. At this time, since X2>Y2, the movement in the Y direction is
It is completed in a shorter time than the direction movement (Fig. 9 A2),
After that, when the needle 3 reaches the uppermost position (corresponding to the midpoint between P2 and P3 in Figure 3), the next movement amount data X3 and Y3 are read out from the floppy disk FP based on the flow in Figure 5. Due to X3>Y3
Letting L3=X3, due to this L3, ω3=a1a2π/L2
is calculated.

Now, in Fig. 3, since X1>X2, the time it takes to move the embroidery frame 5 from P2 to P3 by the stepping motors
2, and since the driving speeds of the stepping motors XSTM and YSTM are constant, the time from when the needle 3 comes out from point P2 to when the stepping motor XSTM stops is , the time from when the needle 3 comes out from point P1 until the stepping motor XSTM stops.
It is reduced to the value multiplied by X2/X1. However, P2-
Drive speed of motor M between P3 ν2=K/L2=K/
X2, and on the other hand, since the driving speed of motor M between P1 and P2 was ν1=K/L1=K/X1, P2
The driving speed ν2 of the motor M between -P3 is X1/X2 times faster than the driving speed ν1 between P1 and P2,
Therefore, the waiting time until the needle 3 penetrates the fabric after the stepping motor XSTM is stopped (B2 in Figure 9)
T2 is never longer than T1. Next, when the needle 3 penetrates the cloth, the servo drive system SB causes ω3=a1a2π/
Since L3 is set, the driving speed of motor M ν3=
K/L3, and as shown in Figure 3, since X2>X3, ν3/ν2 = Since the driving speed of motor M gradually increases in inverse proportion to the length, X3>X4>X5>
Even though the time required to move the embroidery frame 5 decreases due to the narrowing of the distance between X6 and the needle drop point, the needle 3 penetrates the fabric next after the stepping motor XSTM stops, as shown in Figure 4. The waiting time until T3,
T4, T5... will not increase.

In the above embodiment, a circuit DF with a transfer function of G1+SG2 is incorporated into the servo drive system SB in order to improve the start-up characteristics of the motor M, but such a circuit is omitted and the improvement of the start-up characteristics described above is described below. It is also possible to process it software in the CPU as shown below. In other words, the servo drive system
When focusing on the coefficient ωJ・(G1+SG2) of the SB response ωJ・G3・(G1+SG2)・G4・G5/(1+TS), S
= d/dt (t is time), ωJ = a1a2π/LJ to ωJ (G1 + SG2) = a1a2π (G1/LJ - G2/(LJ)2・dLJ/dt) However, LJ changes continuously with time. It is not an amount that changes, but changes discretely for each stitch, such as LJ → LJ + 1 → LJ + 2, etc.

Therefore, by detecting the time △t of one cycle of the motor M, dLJ/dt is calculated by the difference (LJ) - (LJ-1)/△t
Change it with From the above, the program flowchart is as shown in Figure 7, and GJ=a1a2π(G1/LJ−G2/(LJ) ²・(LJ)−(LJ−1)/△t) calculated by this flow. By converting it into an analog value using a D/A and inputting it to the servo drive system SB shown in FIG. 6, it is possible to obtain an improved start-up characteristic of the motor M that is almost equivalent to that shown in FIG.

As described above, according to the present invention, by inputting a value inversely proportional to the value of needle drop point movement amount data to the servo drive system via the D/A, Since the driving speed of the motor M is controlled according to the embroidery frame, the driving speed of the motor M is set to a high speed when the distance between the needle drop points is narrow, and the driving speed of the motor M is set to a low speed when the distance between the needle drop points is wide. This prevents the needle from penetrating the fabric before the embroidery frame stops, which prevents needle breakage and misalignment of the needle drop point, and also reduces the time it takes for the needle to penetrate the fabric after the embroidery frame stops, making it possible to Since the optimum sewing speed is set even for the embroidery stitches, the sewing efficiency can be improved.

[Brief explanation of drawings]

Figure 1 is a perspective view of the embroidery sewing machine, Figure 2 is a diagram of embroidery pattern "A", Figure 3 is an enlarged view of section Q in Figure 2, Figure 4 is a block diagram of the control circuit, and Figure 5 is a diagram of the embroidery pattern "A". FIG. 6 is a flowchart of the CPU program; FIG. 6 is a block diagram of the control circuit of another embodiment; FIG. 7 is a flowchart of the program of another embodiment;
The figure is a conventional time chart showing the relationship between the vertical movement of the needle and the driving of the stepping motor, and FIG. 9 is a time chart showing the relationship between the vertical movement of the needle and the driving of the stepping motor in this embodiment. be. DS...Digital processing system, SB...Servo drive system.

Claims (1)

[Claims] 1. A sewing machine 2 placed on a table 1, a motor M connected to the main shaft of the sewing machine that moves the needle up and down, and whose driving speed can be electrically adjusted; an embroidery frame 5 supported on a table so as to be movable in the X direction and the Y direction perpendicular to the X direction; and a storage means that sequentially stores data on the amount of movement of the embroidery frame in the X and Y directions for each stitch. FP, a readout means for reading out the movement amount data of the storage means for each stitch in connection with the detection of a specific rotation angle of the main shaft, and a readout means connected to the embroidery frame to allow the needle to separate from the fabric based on the read movement amount data. A driving means for moving the embroidery frame in the X and Y directions at a constant speed in relation to the lifting.
XSTM, YSTM, a comparison means that compares the magnitude of the X and Y direction movement based on the read X and Y direction movement amount data, and a comparison means that compares the movement amount based on the larger movement amount data by comparison of the comparison means. A speed control device for an embroidery sewing machine, comprising: a control means for calculating and setting a motor drive speed so as to be inversely proportional to the amount of the motor.