JPS6149994B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a sewing machine that performs zigzag stitches by swinging the needle bar using a cam mechanism that is linked to the rotation of the main shaft. This invention relates to a stop control device for a zigzag sewing machine.

Conventionally, when forming a zigzag stitch along the edge of a cloth W having a corner E as shown in FIG. 7, for example, in order to change the cloth feeding direction at the corner E, the sewing machine is It is necessary to stop the sewing machine at the needle down position, rotate the fabric around the needle that has penetrated the fabric, align the edge of the fabric W with the fabric feeding direction, and then drive the sewing machine again to form the stitches. In sewing machines that do not have position stopping means, the needle may stop without penetrating the fabric, and the next scheduled needle drop point may be shifted when turning the fabric, and even in sewing machines that have position stopping means, When the sewing machine is stopped, such as when performing four-point zigzag stitches, the needle drop point P ₁ is located inward from the outer end needle drop point P.
This causes disadvantages such as not being able to obtain the desired stitches and deteriorating the quality of the product.For this reason, the worker manually fixes the needle to the main shaft until it reaches the specified outer end needle drop point P. This requires turning the pulley, and in sewing machines with fixed position stopping means, the power must be turned off once for this operation, resulting in a drawback that work efficiency is significantly reduced.

The object of the present invention is to eliminate the drawbacks of the above-mentioned conventional devices.

Embodiments of the present invention will be described below with reference to the drawings. In FIG.
A well-known electromagnetic clutch motor 3 having an electromagnetic clutch and an electromagnetic brake is placed below the workbench 2, and a pulley 4 fixed to the main shaft (not shown) of the sewing machine 1 is connected to the electromagnetic clutch motor 3. A needle position detection means is connected to the drive pulley 5 via a belt 6 and is located between the main shaft and the sewing machine frame for detecting the rotation angle of the main shaft corresponding to the lower position of the needle and generating a lower position signal (H level). Place ND. A pedal 9, which is rotatably supported on a horizontal support shaft 8 below the workbench 2, is in a driving state in which the electromagnetic clutch motor 3 is driven in relation to the forward pressing operation. At the same time, in connection with the release operation, a stop signal is generated to stop the electromagnetic clutch motor 3.

Inside the machine frame of the sewing machine 1, a plurality of needle swing cams 11 (a second
) is arranged so that one rotation of the needle oscillating cam 11 performs one cycle of zigzag stitches. In other words, in the case of two-point zigzag stitching, the needle oscillating cam 11 rotates once for every two rotations of the main shaft, and stitches at four points In the case of zigzag, a reduction mechanism (not shown) is arranged in relation to it so that the oscillating cam 11 makes one rotation for every six rotations of the main shaft.
As described in Japanese Patent No. 6784, a cam selection mechanism (not shown) and a needle oscillation mechanism (not shown) that swings the needle 7 by a cam change on the outer peripheral surface of the selected needle oscillation cam 11 are used as the needle oscillation cam 11. Place in relation to. A fixed magnet M is fixed to the outer circumferential surface of the cam 11 on each stylus at a rotation angle corresponding to the needle down position at a predetermined needle drop point, and the magnetism of the magnet M is detected to cause the stylus cam 11 to rotate. A magnetically sensitive element H that generates a rotational signal in relation to the sewing machine frame is fixedly arranged on the sewing machine frame (FIG. 2). 10 is an electric circuit (second
It is a control box that accommodates the electromagnetic clutch motor 3 and pedal 9, which is fixed below the workbench 2.
to be electrically connected.

Next, to explain the electric circuit of this example, in FIG. 2, CNT is an adder circuit,
The lower position signal of the needle position detecting means ND is digitally added, and the added value is cleared in connection with the generation of the rotation signal of the magnetically sensitive element H inputted via the amplifier AP. DS is a digital switch that can be manually operated and generates a different digital code depending on the manual operation position, and COD is an adder circuit.
This is a matching circuit in which the output signal becomes H level when the added value of CNT and the digital code of the digital switch DS input via the encoder EC are equal. The output signal of the coincidence circuit COD is input to one input terminal of the AND gate G, and the lower position signal of the needle position detection means ND is input to the other input terminal.
VC is a speed control circuit composed of a discrete IC, which energizes or deenergizes the solenoid CS of the electromagnetic clutch and the solenoid BS of the electromagnetic brake in relation to the generation of the drive signal of the pedal 9, and controls the amount of the front depression of the pedal 9. is sufficient to cause the spindle to rotate at a speed proportional to , and to deenergize the solenoid BS in relation to the H level of the output terminal of the AND gate G when a stop signal is generated, and cause the solenoid BS to stop the rotation of the spindle. It is energized for a certain time Δt (Figs. 5 and 6).

In the above configuration, a case will be described in which, for example, the needle swing cam 11 that performs two-point zigzag stitch is selected. In FIG. 3, it is assumed that the sewing machine 1 is stopped in the needle down position at the needle drop point _P1 and a rotation signal is generated opposite the magnetically sensitive element H, and the digital switch is set to "1", for example. When the pedal 9 is pressed forward and a drive signal is input to the speed control circuit VC,
The speed control circuit VC drives the electromagnetic clutch motor 3. As the needle 7 moves up and down, the detection means ND alternately generates an upper position signal and a lower position signal, and the addition circuit
CNT adds the lower position signal and the needle 7 is at the needle drop point P ₁₁
When the second lower position signal is generated, the needle swing cam 11 rotates once, the magnetically sensitive element H generates a rotation signal, and the added value of the adder circuit CNT is cleared. Therefore, as shown in FIG. 5, the added value repeats "0" and "1" every time the lower position signal is generated.
When the hand 7 is located at point A before point _P1 , the added value "1" and the set value "1" of the digital switch DS match, so the output signal of the matching circuit COD is at H level, and in this state , when a lower position signal is generated at needle drop point P ₁ , the output terminal of AND gate G becomes H.
level, but since the drive signal for the pedal 9 is input to the speed control circuit VC, the main shaft does not stop. Even if the needle 7 passes the needle drop point _P11 and a stop signal is generated by releasing the pedal 9 at point B between points _P1 and _P2 , the addition value of the addition circuit is "0". The output signal of the coincidence circuit COD is at L level,
Therefore, since the AND gate G is at the L level, the motor 3 does not stop, and when the needle 7 reaches the needle drop point _P2 , the added value becomes "1", and the coincidence circuit is activated.
The output signal of COD becomes H level, and the output terminal of AND gate G becomes H level due to the output signal and the lower position signal, so the speed control circuit VC energizes solenoid BS for a time △t to control the electromagnetic clutch motor 3. The needle 7 stops while penetrating the fabric at the needle drop point _P2 . Furthermore, when the needle 7 passes the needle drop point P ₂ and the pedal 9 is released at point C between points P ₂ and P ₁₁ , the output of the matching circuit COD becomes H because the added value is "1". Although the level is
When the lower position signal is generated at needle drop point P ₁₁ ,
At the same time, the added value is cleared and becomes "0", so the output of the coincidence circuit COD becomes L level and the output terminal of AND gate G remains at L level, and when needle 7 reaches the needle drop point _P12 , the added value becomes "1" and the output of the AND gate G becomes H level, so as mentioned above, the speed control circuit VC stops the electromagnetic clutch motor 3, and the needle 7 stops while penetrating the cloth at the needle drop point _P12. . If you want to stop the hand 7 on the P ₁ and P ₁₁ sides, set the digital switch DS to "0".

Next, the needle swing cam 1 performs, for example, 4-point zigzag stitches.
The case where 1 is selected will be explained. digital switch
For example, set DS to "2". When the pedal 9 is operated to input a drive signal to the speed control circuit VC to drive the electromagnetic clutch motor 3, the added value repeats "0" to "5" every time the lower position signal is generated, as shown in FIG. Even if the operation of pedal 9 is stopped when needle 7 rises from needle drop point P ₄ and is located at point A, the additional value "3" is added because the setting value "2" of digital switch DS does not match, as described above. As shown, the rotation of the main shaft does not stop, and when the needle 7 reaches the needle drop point _P13 and penetrates the fabric, the added value and the set value of the digital switch DS match, so the speed control circuit VC controls the brake solenoid BS for a time △ The rotation of the main shaft is stopped by applying force by t, and the needle 7 penetrates the cloth at the needle drop point _P13 and stops.

Above, we have explained 2-point and 4-point zigzag stitches, but in general, multi-point zigzag stitches with 4 or more points are also explained.
By switching the needle oscillation cam and appropriately determining the set value of the digital switch DS, it is possible to stop the needle 7 at any desired needle drop point with the above configuration.

In addition, the upper position signal instead of the lower position signal of the needle detection means ND is added to the addition circuit CNT, and
After inputting the lower position signal to the AND gate G and adding the upper position signal, the solenoid BS may be energized by the speed control circuit VC in synchronization with the preceding position signal.

Furthermore, in electrically controlled sewing machines, the circuit corresponding to the speed control circuit VC in the above embodiment is usually configured with a discrete IC or a microcomputer, so that the main shaft rotates once the drive signal is stopped. It is also possible to easily reduce the speed and make the needle stop more secure.

In addition, when using a normal DC motor etc. as a drive motor, the speed control circuit VC in the above embodiment
may be omitted, and the output of the AND gate G may be used to operate a braking means as described in, for example, Japanese Patent Application No. 73424/1983 filed by the present applicant.

As described above, according to the present invention, in a sewing machine that performs zigzag stitches by swinging the needle bar using a cam mechanism that is linked to the rotation of the main shaft, a circuit that sequentially counts each stitch corresponding to one cycle of zigzag stitches is provided. At the same time, the numerical value can be set in advance, and when the counted value and the set value match, the brake means is activated to stop the rotation of the main shaft, thereby making it possible to stop the needle at a predetermined position corresponding to the stitch. , even when stitching the edges of the cloth using zigzag stitches, as in the past,
This has the effect of improving work efficiency by eliminating the need to manually rotate a pulley fixed to the main shaft at the edge of the fabric after stopping the rotation of the main shaft to move the needle. By doing so, accurate stitches can be continuously formed without shifting the stitches when changing the sewing direction, which has the effect of improving the quality of the product. Furthermore, since it is possible to stop the needle at any position corresponding to a stitch in multi-point zigzag stitching, it is possible to create a wide variety of sewing patterns by appropriately changing the setting of the stopping position.

[Brief explanation of the drawing]

Fig. 1 is a front view of the sewing machine of this embodiment, Fig. 2 is an electric circuit block diagram of the sewing machine of this embodiment, Fig. 3 is a diagram showing a two-point zigzag stitch, and Fig. 4 is a diagram showing a four-point zigzag stitch. 5 is a time chart for the zigzag stitch shown in FIG. 3, FIG. 6 is a time chart for the zigzag stitch shown in FIG. 4, and FIG. 7 is a diagram showing the conventional zigzag stitch. In the figure, 9 is a pedal, 11 is a needle swing cam,
M is a magnet, H is a magnetic sensing element, ND is a needle position detection means, CNT is an addition circuit, DS is a digital switch, COD is a matching circuit, VC is a speed control circuit,
BS is the electromagnetic brake solenoid, and CS is the electromagnetic clutch solenoid.

Claims (1)

[Scope of Claims] 1. A needle bar swinging mechanism that swings the needle bar in a direction crossing the cloth feeding direction, a main shaft that rotates around a fixed straight line to move the needle bar up and down, and a main shaft that can be rotated or stopped. In a zigzag stitch sewing machine having a motor connected to the main shaft, an operating means that generates a drive signal in connection with operation in one direction and a stop signal in connection with operation in the other direction, and an operation means arranged in relation to the main shaft and at the needle lower position. needle position detection means that detects a predetermined rotation angle of the main shaft corresponding to the rotation angle and generates a position signal; A needle oscillation cam connected to a needle bar swinging mechanism so as to displace the needle bar to a plurality of predetermined needle oscillation positions in relation to displacement of the outer peripheral cam surface in the center; a rotation detection means that generates a rotation signal at a predetermined rotation angle of the needle swing cam corresponding to the needle swing position at one end of the needle swing range set by the cam; A setting means that generates different setting signals, an addition circuit that adds the position signal of the needle position detection means and clears it in relation to the generation of the rotation signal of the rotation detection means, and an addition value of the addition circuit that is added to the setting value of the setting signal. a comparison circuit for generating a match signal in connection with the match; and an associated control circuit for driving the motor in connection with the generation of the drive signal and stopping the motor in connection with the generation of the stop signal and the match signal. The setting means is set to a value smaller than the number of needle swing positions associated with one rotation of the needle swing cam, and the needle is stopped at a desired position among the needle swing positions set by the needle swing cam. A stop control device for a zigzag sewing machine.