JP2000070582A - Reserve feed controller for sewing machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a reserve feed controller capable of sewing while almost vertically stringing a needle into fabric even when a fabric feeding direction is converted while maintaining the rotation of a sewing machine at any arbitrary speed. SOLUTION: In this reserve feed controller for sewing machine is provided with a feed converting means for converting the fabric feeding direction backward or forward by driving a driving member 4 to be electrically operated while having a pedal 7 for commanding the speed of the sewing machine corresponding to stepping operation, reserve feed switch 6 for generating a signal for instructing the inversion of the fabric feeding direction through the operation and driving member 4. This device is also provided with a rotating angle detecting means 12 for detecting the rotating angle of the main shaft of a sewing machine 1, speed detecting means for detecting the speed of the sewing machine, and control means for controlling the driving member 4 at the timing included in the prescribed rotating angle range of an upper shaft while changing the speed of the sewing machine into prescribed speed based on the operation of the reserve feed switch 6.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reverse stitch control device for a sewing machine which prevents diagonal stitches in a cloth by turning on or off a reverse stitch switch for performing reverse stitching.

[0002]

2. Description of the Related Art Conventionally, a button switch provided on a sewing machine head is pressed during sewing by a pedal front depression (also referred to as a toe depression) operation, so that the electric power of the magnet or the like is maintained for an arbitrary number of stitches. The cloth driving direction is reversed by operating the mechanical drive means, so that a so-called reverse stitch is formed. Further, when the predetermined stitch formation is completed, the sewing machine pedal is stepped backward (also referred to as heel stepping), so that the electric driving means is automatically operated for a predetermined number of stitches to reverse the cloth feeding direction, A so-called stop stitch was formed.

[0003] Usually, in this reverse sewing, a feed amount setting cam called a ginkgo cam and a feed conversion mechanism comprising a link mechanism and the like are operated by the electric drive means to set the feed amount to a minus value. This is achieved by converting a feed dog which is performing a forward feed motion in conjunction with the above-mentioned feed motion into a reverse feed motion based on the minus feed amount.

Due to the structure of the feed conversion mechanism, when the electric driving means is operated, the feed conversion mechanism is switched from the previous normal feed set position to the reverse feed set position beyond the zero feed position. Then, the feed dog is instantaneously displaced in the front-rear direction from the previous feed motion position, and then the feed motion in the reverse direction is performed in conjunction with the main shaft.

In general, due to the structural characteristics of the feed conversion mechanism, the instantaneous displacement of the feed dog in the front-rear direction corresponds to the main shaft corresponding to a predetermined range before the needle point enters the needle hole of the needle plate. In the range of the rotation angle, the displacement amount becomes maximum.

Accordingly, when the feed conversion mechanism operates within this rotation angle range, the feed dog is displaced greatly in a timely manner with the needle piercing the cloth, so that the cloth is rapidly sent and the cloth is damaged by the needle. Or the needle penetrates while the cloth is being sent abruptly, so that the needle penetrates diagonally with respect to the cloth, and the pitch of the upper and lower threads appearing on the front and back of the cloth as shown in FIG. Differently, the seams were unsightly and could reduce the commercial value.

As shown in FIG. 12, usually, after the electric driving means such as the magnet is started to be electrically energized,
An operating member such as the plunger is gradually displaced, and it takes a time (Δt) until the feed dog is actually brought into the reverse feed state by the feed conversion mechanism connected to the operating member.

At the time of reverse stitching by the manual switch operation, the sewing machine speed is determined by the operation amount of the operator's stepping on the front of the pedal. Therefore, the switch operation may be performed while the sewing machine is driven at a speed lower than the stop sewing speed. . In this case, as shown in FIG. 12, the elapsed time of the time Δt may be a time when the needle point N is pierced into the cloth W above the needle plate P, and as described above, the cloth may be damaged or the diagonal sewing may be performed. Problem appears.

Therefore, it is extremely difficult for the operator to perform the reverse stitching by operating the manual switch so as not to cause the above-mentioned inconvenience, and the working efficiency has been significantly reduced.

Similarly, the same can be said when the manual switch is operated so as to end the reverse stitching.

For this reason, when the sewing machine is driven within the predetermined speed, the back tack switch is operated so that the back tack solenoid completes its operation and the feed dog ends when the needle tip does not pierce the cloth. The upper shaft rotation angle (back-tack switch accepting section) at which the on / off signal of No. 6 can be input has been set.

For example, as shown in FIG. 13, when the rotation speed of the sewing machine is a predetermined speed, for example, 1000 rpm or less, the upper shaft angle at which the needle completely descends from the upper surface of the needle plate, as shown in FIG. To the upper axis angle beyond the top dead center, and if an ON or OFF signal from the back tack switch enters this angle range,
When the time Δt, which is the time from when the back tack solenoid 4 is energized to when the feed conversion mechanism enters the reverse feed state, elapses, the position of the needle tip becomes T1, so that the needle does not stick into the cloth.

[0013]

However, the time at which the needle pierces the cloth varies depending on the thickness of the cloth to be sewn, and the Δt varies depending on the feed pitch or the voltage applied to the back tack solenoid. Would. For example, if the cloth becomes extremely thick, as shown in FIG. 12, the needle tip may pierce the cloth when the time Δt has elapsed as described above. In addition, when the feed pitch is long or the voltage is low, the Δt is long, and the time when Δt has elapsed may be the time when the needle tip pierces the cloth.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has as its object to sew a sewing machine by piercing a cloth almost vertically into a cloth even if the cloth feeding direction is changed while the sewing machine is rotating at an arbitrary speed. It is an object of the present invention to provide a reverse stitching control device capable of performing the above.

[0015]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, a first aspect of the present invention provides a pedal for commanding the speed of a sewing machine in accordance with a depression operation, and a reverse stitch for generating a signal for instructing a reverse of a cloth feed direction by the operation. A switch and a feed conversion unit that has a drive member that is electrically operated and that converts a cloth feed direction to a reverse direction or a forward direction by driving the drive member.
A rotation angle detection unit that detects a rotation angle of a main shaft of the sewing machine, a speed detection unit that detects a speed of the sewing machine, and a speed of the sewing machine that is changed to a predetermined speed based on an operation of the reverse stitch switch, and Control means for driving the driving member of the feed conversion means at a timing included in the rotation angle range of the upper shaft.

According to the first aspect of the present invention, the control means determines whether or not the reverse stitching switch is on or off.
Since the speed of the sewing machine is changed to a predetermined speed and the driving member of the feed converting means is operated at a timing when the rotation angle of the sewing machine is included in a predetermined angle range, the cloth feeding direction of the cloth feeding is changed. Even if the cloth feed direction is changed by turning the reverse stitch switch on or off during the rotation of the sewing machine, the angle at which the needle that moves up and down with the rotation of the sewing machine penetrates the cloth becomes substantially vertical, and the thread is pulled in the cloth. Even if the material to be sewn becomes thicker, sewing can be performed almost vertically.

Here, specifically, the control means includes, for example, a CPU (Central Processing Unit), a RAM (Ra
It can be configured by a digitally controllable control circuit or the like including an ndom access memory (ROM) and a read only memory (ROM), and may also be used as a control circuit for controlling other parts of the sewing machine. The feed conversion means (for example, an electromagnetic solenoid) is connected to the feed conversion mechanism, and drives the driving member (for example, a plunger) to change the cloth feeding direction to the reverse direction or the forward direction.

According to a second aspect of the present invention, in the reverse sewing control device for a sewing machine according to the first aspect, when the driving of the driving member for changing the cloth feeding direction is completed, the speed returns to the speed of the pedal command from the speed of the predetermined condition. The configuration is such that control is performed.

According to the second aspect of the invention, the same effect as that of the first aspect of the invention can be obtained, and the speed of the sewing machine changed to the predetermined speed by the control means is increased by the drive speed. Since the operation is controlled so as to return to the speed of the pedal command after the operation of the member is completed, only when the feed direction of the cloth feed based on the on / off of the reverse stitching switch is changed, that is, the drive member operates. Only during this time, the speed of the sewing machine becomes the predetermined speed. Thus, for example, if the predetermined speed is lower than the speed of the pedal command before the reverse stitching, the speed of the sewing machine decreases only while the drive member operates, and after the operation, the speed is changed to the speed of the pedal command. Otherwise, the speed returns to the previous speed, so that the cycle time of reverse stitching can be shortened.

According to a third aspect of the present invention, in the reverse sewing control device for a sewing machine according to the first aspect, the sewing machine further comprises a pitch detecting means for detecting a cloth feed pitch, and the control means is configured to output the cloth feed pitch based on an output of the pitch detecting means. The predetermined speed is set.

When the pitch of the cloth feed changes, the operation time of the feed converting means for changing the cloth feed direction changes. That is, if the pitch of the cloth feed increases, a load is applied to the feed conversion means, and the load on the feed conversion means increases the operation time of the drive member.

According to the third aspect of the invention, the same effect as that of the first aspect of the invention can be obtained, and by operating from the cloth feed pitch detected by the pitch detecting means, An operation time of the drive member for changing the feed direction of the cloth feed is set, the drive member is operated at the predetermined speed set based on the operation time, and at a speed suitable for the pitch at this time. The direction of the cloth feed can be changed.

According to a fourth aspect of the present invention, there is provided the reverse sewing control device for a sewing machine according to the first aspect, further comprising a cloth thickness detecting means for detecting a cloth thickness, wherein the control means is configured to detect a cloth thickness based on an output of the cloth thickness detecting means. Thus, the predetermined speed is set.

According to the fourth aspect of the invention, the same effect as that of the first aspect can be obtained, and
Since the feed direction of the cloth feed can be changed at the predetermined speed set in accordance with the cloth thickness detected by the cloth thickness detecting means, the feed direction of the cloth feed at a speed adapted to the cloth thickness of the work to be sewn. Conversion can be performed.

According to a fifth aspect of the present invention, in the reverse sewing control device for the sewing machine according to the first aspect, the feed conversion means is an electromagnetic solenoid, and a solenoid voltage detection means for detecting an amount of voltage applied to the solenoid is provided. The control means sets the predetermined speed based on an output of the solenoid voltage detection means.

According to the fifth aspect of the invention, the same effect as that of the first aspect of the invention can be obtained.
An operation time of a plunger (drive member) of the solenoid is set from an amount of voltage applied to the solenoid detected by the solenoid voltage detection means, and at a predetermined speed set based on the operation time of the plunger,
Since the plunger of the solenoid can be operated, at the predetermined speed adapted to the response time of the solenoid (operation time of the solenoid) from receiving the operation command of the plunger in the solenoid until the end of the operation of the plunger, The plunger of the solenoid can be operated to change the feed direction of the cloth feed.

According to a sixth aspect of the present invention, there is provided a cloth thickness detecting means for detecting a cloth thickness.
A control means is provided for controlling the drive member of the feed conversion means to be operated at a timing included in the changed rotation angle range by changing the predetermined rotation angle range.

According to the sixth aspect of the invention, the same effect as that of the first aspect can be obtained,
The control unit varies a predetermined angle range of the sewing machine rotation angle in accordance with a detection output of the cloth thickness detection unit, and operates a driving member of the driving unit at a timing included in the varied angle range. , It is possible to reduce the sewing cycle time.

[0029]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a first embodiment of the present invention will be described with reference to FIGS.

As shown in FIG. 1, a sewing machine 1 having a reverse stitch control device according to the present invention has a sewing machine motor 2 for driving the sewing machine and a feed conversion mechanism (not shown) for changing the feed direction of the feed dog. Back-tack solenoid that is connected to and operates on the
TSOL: feed conversion means) 4, a photosensor for detecting the position of the plunger (drive member) of the back tack solenoid 4, or a plunger position detector 5 comprising a non-contact or contact type limit switch or the like.
Back-tack switch (BTSW in the drawing) 6 for giving an instruction signal to start or end reverse stitching; foot pedal 7 for changing the rotation speed of the sewing machine according to the amount of front depression; cloth for detecting the cloth thickness A thickness detector (cloth pressure detecting means) 8, a pitch detector (pitch detecting means) 9 which is arranged in the feed conversion mechanism and detects a cloth feed pitch, and a sewing machine main shaft (upper shaft) which is rotated by driving the sewing machine motor 2. ) Is roughly composed of a rotation angle detector (rotation angle detection means) 12 composed of an encoder arranged in relation to the upper shaft so as to detect the rotation angle, a control box 10, and the like.

The back tack solenoid 4 is provided in the sewing machine bed 1a. As shown in FIGS. 6 and 7, the back tack solenoid 4 is provided on a feed adjusting body 54 constituting a link mechanism 53 of a cloth feed section 52 for operating a feed dog 51. Are connected,
The plunger 43 advances and retreats in the reciprocating movement space S formed in the cylindrical coil 42 in the U-shaped yoke 41,
By changing the position of the fulcrum 55 of the cloth feeder 52 that moves the feed dog 51 and changing the trajectory of the feed dog 51, the cloth feed direction is changed.

That is, the back tack solenoid 4 is controlled based on a reverse stitch start signal input to the back tack solenoid 4 from a control circuit (control means) 11 described later.
The coil 42 is excited, and the plunger 43 advances in the direction of arrow A to be pulled out, and pulls the connecting rod 46 via the connected connecting link 44 and rotating link 45. The position of the fulcrum 55 of the cloth feeder 52 connected to the connecting rod 46 is changed to change the trajectory of the feed dog 51, and the cloth feed direction of the workpiece to be sent is reversed.

When a reverse stitching end signal from the control circuit 11 is input to the back tack solenoid 4,
Based on this signal, the plunger 43 returns in the direction opposite to the arrow A, and the cloth feeder 5 is connected via the connected connecting rod 46.
The position of the fulcrum 55 of the second link mechanism 53 is returned, and the cloth feeding direction is changed to the forward direction.

The control box 10 includes a CPU (Central Pr
Ocessing Unit), RAM (Random Access Memory) RO
The control circuit 11 includes an M (Read Only Memory), an interface (not shown), and the like. The control circuit 11 includes a sewing machine motor 2, a back tack solenoid 4,
The back tack switch 6, the foot pedal 7, and various detectors (plunger position detector 5, cloth thickness detector 8, pitch detector 9, rotation angle detector 12, etc.) provided on the sewing machine 1 are connected.

In addition to the control circuit (control means) 11, the control box 10 includes a head selector 13 for detecting the type of the sewing machine head and a back tack solenoid voltage detector (for detecting the voltage supplied to the back tack solenoid 4). The head selector 13 and the back tack solenoid voltage detector 15 are connected to the control circuit 11, respectively.

The control circuit (control means) 11 has a function of reading a signal from the rotation angle detector 12, detecting the motor rotation speed, that is, the rotation speed, and controlling the motor rotation speed based on the signal.

The back tack switch 6, when pressed by an operator, generates an ON or OFF signal for reverse stitching and is input to the control circuit 11 of the control box 10. The control circuit 11 changes the cloth feeding direction. To the back tack solenoid 4.

The rotation angle detector 12 detects that the upper dead center of the needle bar that moves up and down becomes 0 degree at the rotation angle of the upper shaft rotated by the sewing machine motor 2. At the rotation angle, an allowable section in which the back tack switch 6 can be received (hereinafter referred to as a back tack switch receiving section) is detected in advance.

The back tack switch acceptance section is
When the sewing machine is driven at a predetermined speed, if the ON / OFF signal of the back tack switch 6 is input during this section, the motion of the feed dog due to the movement of the back tack solenoid 4 causes the inside of the cloth to move. This is the range of the upper axis angle at which diagonal sewing and breakage of the cloth can be prevented.

In this embodiment, for example, the range is from the upper axis angle (start angle: 112 degrees) to the upper axis angle (end angle: 262 degrees).

It should be noted that the back tack switch receiving section at this upper axis angle can be widened by increasing the energizing voltage to the back tack solenoid 4 to shorten the moving time of the plunger 43.

The position of the plunger 43 can be detected by the plunger position detector 5 in a fully pulled state and a fully returned state.

The cloth thickness detector 8, for example, detects the amount of rise of the cloth presser from the needle plate when the work on the sewing table is pressed by the cloth presser, thereby detecting the thickness of the work to be sewn. It is configured to be able to detect, and outputs the detected cloth thickness signal to the control circuit 11. The cloth thickness detector 8 may be one that irradiates the cloth with light and detects the thickness in a reflective or transmissive manner.

The pitch detector 9 detects the pitch of the cloth feed by detecting the position of a pitch changing operation rod (not shown) provided in the cloth feed section with a photo sensor or the like. Note that the pitch changing operation rod changes the locus of the cloth feeding by changing a predetermined fulcrum of the cloth feeding section 52 to perform the cloth feeding, and is a known technique.

The head selector 13 is for selectively inputting the type of the sewing head to be used, that is, the type of the sewing machine. Specifically, it is based on the input setting from a panel or the like by an operator, the selection setting of a dip switch or the like, or the setting for automatically identifying the head.

The input of the head selector 13 is used to read out the thickness data of the needle plate according to the sewing machine head type and use it as basic data of cloth thickness measurement or to detect an angle range under predetermined conditions described later. It is possible to

Back tack solenoid voltage detector 15
Detects the voltage sent to the back tack solenoid 4 and outputs the signal to the control circuit 11.

In order to prevent the needle from performing diagonal stitching due to the movement of the cloth associated with the back tack solenoid 4 when performing reverse stitching, the timing at which the needle stabs the cloth from the rotation angle corresponding to the back tack switch receiving section. During the rotation to the rotation angle corresponding to, the back tack solenoid 4
The movement to the forward end or the backward end may be completed.

The time from when the needle tip touches the cloth to when the needle tip comes out of the cloth must be shorter than the time required for the back tack solenoid 4 to move the distance from the center of the needle hole to the end of the needle hole.

When the cloth becomes thicker, the time from the end rotation angle of the back tack switch receiving section to the time when the needle is put on the cloth becomes shorter, so it is necessary to change the rotation speed of the sewing machine.

It is necessary to change the rotation speed of the sewing machine based on the cloth feed pitch signal output from the pitch detector 9. For example, if the cloth feed pitch is larger than the initially set cloth feed pitch, a load is applied to the back tack solenoid 4, and when the back tack solenoid 4 is operated in a state where the pitch is large, the back tack solenoid is operated. The response time from the receipt of the command to start or finish the reverse stitching by the back tack 4 to the end of the operation of the plunger 43 of the back tack solenoid 4 becomes longer.

That is, when the cloth feed pitch changes, the moving amount of the sewing object also changes, and the operation time of the back tack solenoid 4 also changes.

Further, as described above, the back tack solenoid 4 is controlled by the voltage applied to the back tack solenoid 4.
Plungers move forward and backward differently.

For this reason, the control circuit 11 includes the cloth thickness detector 8,
Pitch detector 9, back tack solenoid voltage detector 1
By reading the signal detected from 5, the lower limit rotation speed and the upper limit rotation speed of the rotation speed of the sewing machine, which are the rotation speeds of the predetermined condition at the time of reverse stitching, are determined.

The reverse stitching control process of the reverse stitching control device having the above configuration will be described with reference to FIGS.

In FIG. 3, when performing reverse stitching, the user sets the back tack switch 6 in step S1.
When the button (denoted as BTSW) is pressed and an ON signal for starting reverse feed stitching is input, the process proceeds to step S2.

In step S2, the rotation state of the sewing machine is checked based on the output from the rotation angle detector 12. At this time, if the sewing machine is stopped, the process proceeds to step S3, in which the back tack solenoid 4 (denoted as BTSOL) is turned on, and the cloth feeding direction is changed to the reverse feeding.

On the other hand, if the sewing machine is rotating, the cloth thickness at that time, the solenoid voltage detection, and the sewing pitch are detected (steps S4 to S6), and the lower limit rotation speed A and the upper limit rotation speed are determined based on these detections. Set the speed B (step S
7) Yes.

Step 7 is a subroutine. As shown in FIG. 8, when voltage detection or feed pitch detection is performed (step S71), the detected solenoid voltage data and feed pitch data are read out (step S7).
2) The movement time Ts of the back tack solenoid 4 to the front and rear ends is read from a table (hereinafter referred to as a first table) stored in advance (step S73). Subsequently, or when the solenoid voltage or the cloth pitch is not detected in step S71, a rotation angle tn corresponding to the time at which the needle tip pierces the cloth is detected in advance by the detected cloth thickness data (the second table and the second table). Is performed (step S74), and the rotation angle t that pierces the cloth is determined from the end rotation angle of the back tack receiving section.
Until n, the speed at which the motor can rotate during the movement time Ts is obtained by calculation (step 75).

Next, the data of the needle hole radius used for the used sewing machine head is read out from the output of the head selector 13 (step S76), and the plunger of the back tack solenoid 4 is driven by the needle at the same solenoid voltage and pitch under the same conditions. The solenoid drive time Tr required to move by a distance corresponding to the radius of the hole is read from a table (third table) stored in advance (step S77). Further, the upper shaft rotation angle sn corresponding to the time required for the needle tip to move the detected cloth thickness distance is read from a table (hereinafter referred to as a fourth table) stored in advance (step S78). Then, a speed at which the rotation angle sn can be rotated by the solenoid drive time Tr is obtained by calculation (step S79), and this is set as the upper limit rotation speed B.

In step S8, the rotation speed of the sewing machine at this time is compared with the set lower limit rotation speed A. If the rotation speed of the sewing machine is lower than the lower limit rotation speed A, the process proceeds to step S9.

In step S9, it is determined whether or not the upper shaft angle of the sewing machine is in the back tack switch accepting section.
Then, the back tack sewing is performed by turning on the back tack solenoid 4 to change the cloth feed in the reverse direction.

On the other hand, if the rotation speed of the sewing machine is higher than the lower limit rotation speed A in step S8, the process proceeds to step S11.

In step S11, the rotational speed of the sewing machine is compared with the upper limit rotational speed B calculated in step S7. If the rotational speed is higher than the upper limit rotational speed B, the process proceeds to step S3, where the back tack solenoid is operated. In step 4, a process of turning on the sewing machine is performed, and reverse stitching is performed.

In step S11, if the rotation speed of the sewing machine compared with the upper limit rotation speed B is lower than the upper limit rotation speed B, the process proceeds to step S12.

In step S12, the sewing machine motor 2 is subjected to a process of lowering the sewing machine rotation speed to the lower limit rotation speed A, and the process proceeds to step S13 to confirm the processing. That is, in step S13, the output signal output from the rotation angle detector 13 is read, and it is determined whether the sewing machine rotation speed has decreased to the lower limit rotation speed B.
If the rotation speed has decreased to the lower limit rotation speed B, the process proceeds to step S1.
Move to 4.

In step S14, it is determined whether or not the upper shaft angle of the sewing machine is in the back tack switch accepting section.
Then, in step S15, the back tack solenoid 4 is turned on, and the process proceeds to step S16.

In step S16, when it is read that the plunger 43 has been pulled out based on the signal from the plunger position detector 5, the process proceeds to step S17, and the speed of the foot pedal 7 command is transmitted to the sewing machine motor 2. Is performed.

Next, control processing of the reverse stitching control device when the reverse stitching is completed will be described with reference to FIG.

In step S18, when the user releases the back tack switch 6, the control circuit 11
Is in the state where the off signal has been input to step S19.
Move to

In step S19, the rotation angle detector 12
Check the rotation status of the sewing machine by the output of. At this time, if the sewing machine is stopped, the process proceeds to step S20, in which the back tack solenoid 4 is turned off, the cloth feeding direction is changed to the normal direction, and the control of the reverse stitching is completed.

On the other hand, if the sewing machine is rotating, the cloth thickness at that time, the solenoid voltage detection, and the sewing pitch are detected (steps S21 to S23), and the cloth thickness detector 8 which performs these detections, the solenoid voltage Based on the output signals from the detector 15 and the pitch detector 9, a lower limit rotation speed A and an upper limit rotation speed B are set in the same manner as in Step 7 (Step S24).

In step S25, the rotation speed of the sewing machine at this time is compared with the set lower limit rotation speed A. If the rotation speed of the sewing machine is lower than the lower limit rotation speed A, the process proceeds to step S26.

In step S26, it is determined whether or not the upper shaft angle of the sewing machine is in the back tack switch accepting section.
27, the back tack solenoid 4 is turned off, the cloth feeding direction is changed to the forward direction, and the reverse stitching control processing is ended.

On the other hand, if the rotation speed of the sewing machine is higher than the lower limit rotation speed A in step S25, step S28
Move to.

In step S28, the rotational speed of the sewing machine is compared with the upper limit rotational speed B calculated in step S24. If the rotational speed is higher than the upper limit rotational speed B, the process proceeds to step S20 and the back tack solenoid 4 Is performed, and the reverse stitching control is terminated.

In this step S28, if the rotation speed of the sewing machine compared with the upper limit rotation speed B is lower than the upper limit rotation speed B, the process proceeds to step S29.

In step S29, the sewing machine motor 2
Output the deceleration signal to the sewing machine,
Then, the process proceeds to step S29, and the confirmation is performed.

That is, in step S30, it is determined from the output of the rotation angle detector 12 whether or not the sewing machine rotation speed has decreased to the lower limit rotation speed A. If the rotation speed has decreased to the lower limit rotation speed A, the process proceeds to step S31. Move to

In step S31, it is determined whether or not the upper axis angle of the sewing machine is in the back tack switch receiving section.
Then, in step S32, the back tack solenoid 4 is turned off, and the process proceeds to step S33.

In step S33, the operating position of the plunger 43 of the back tack solenoid 4 that has been turned off is detected by the plunger position detector 5, and the plunger 43 is detected based on the signal from the plunger position detector 5.
When it is read that the state has returned from the pulled-out state at the time of the ON operation to the fully returned state, the flow shifts to step S34.

In step S34, the sewing machine motor 2
Then, processing for returning to the speed of the foot pedal 7 command is performed, and the reverse sewing control is terminated.

FIG. 5 shows the back tack switch (BTSW in the figure) 6, the upper shaft rotation angle, the back tack solenoid (BTSO in the figure) in the reverse stitching processing as described above.
L) 4, rotation speed of sewing machine, back tack solenoid 4
4 shows a timing chart showing the movement of the plunger 43, the timing of each operation, and the operation timing.

In the chart of “upper shaft rotation angle”, even if the back tack switch of the upper shaft rotation angle is received and the back tack solenoid 4 is turned on, the needle interlocking with the upper shaft rotates on the cloth. "Back-tack solenoid" indicates sections that do not touch diagonally and sections other than that
Is a chart showing the ON / OFF of the back tack solenoid operation, and the chart of “Back tack solenoid operation (BTS
OL movement) chart is for back tack solenoid 4
4 shows the movement of the plunger 43 included in FIG.

First, when the back tack switch 6 is turned on, the rotation speed of the sewing machine starts to decrease to a lower limit rotation speed which is a predetermined rotation speed. In other words, the timing at which the rotation speed of the sewing machine is reduced is when the back tack switch 6 issues a reverse stitching ON command. With the rotation speed of the sewing machine reduced to the lower limit rotation speed, wait until the rotation angle of the upper shaft enters the back tack switch acceptance section, and when the back tack switch acceptance section is reached, input an ON signal to the back tack solenoid 4 Is performed, and the back tack solenoid 4 is turned on.

After the back tack solenoid 4 is turned on, the plunger 43 of the back tack solenoid 4 is turned on.
Operates, and after the operation of the plunger 43 is completed,
That is, after the plunger 43 is completely pulled and the cloth feeding direction is reversed, the rotation speed of the sewing machine is increased to the original rotation speed, and reverse sewing is performed.

As shown in the chart, while the sewing machine speed during the reverse sewing is returning to the original speed, the back tack switch 4 is kept on, and the plunger 43 of the back tack solenoid 4 is pulled out. It remains in the state.

When the reverse stitching is to be ended, first, the back tack switch is turned off.

When the back tack switch 4 is turned off, the rotation speed of the sewing machine starts to decrease to the lower limit rotation speed, the rotation speed of the sewing machine reaches the lower limit rotation speed, and the rotation angle of the upper shaft is in the back tack switch acceptance section. Then, an off signal is output to the back tack solenoid 4.

When an off signal is input to the back tack solenoid 4, the plunger 4 of the back tack solenoid 4
3 returns to the original position, and when it has completely returned, the rotation speed of the sewing machine increases and returns to the original speed.

As described above, according to the reverse feed stitching control device of this embodiment, the control circuit 11 controls the rotation speed of the sewing machine to the lower limit rotational speed (the rotational speed under a predetermined condition) based on the on / off operation of the reverse feed switch 6. ) And the plunger 43 of the back tack solenoid 4 is operated at the timing when the rotation angle of the sewing machine is included in the back tack switch receiving section (angle range of the predetermined condition) to change the cloth feeding direction of the cloth feeding. Even if the cloth feeding direction is changed during rotation of the sewing machine, the angle at which the needle touches the cloth in the cloth is within a predetermined inclination angle, and the thread is not drawn in the cloth, and the cloth is almost vertically. You can sew. Further, even when the material of the sewing material becomes thick, the sewing can be performed substantially vertically.

When the reverse sewing is started, the rotation speed of the sewing machine changed to the lower limit rotation speed increases after the operation of the plunger 43 is completed and returns to the original rotation speed. Only when changing the feed direction of the cloth feed based on the OFF, the rotation speed of the sewing machine becomes the lower limit rotation speed, and the sewing can be performed at the original rotation speed during the reverse sewing, and the cycle time of the reverse sewing can be shortened.

In the above-described lower limit rotation speed control (rotation speed under predetermined conditions), the change in the rotation speed of the sewing machine for rotating the upper shaft, the back tack switch receiving section of the upper shaft rotation angle, and the start of the operation of the back tack solenoid. The optimum relationship with the time until the end can be obtained by performing a sewing test under various conditions.

In the above embodiment, the plunger position detector 5 is used to detect the movement of the plunger of the back tack solenoid 4. However, the present invention is not limited to this, and a timer may be used instead. That is, when increasing the rotation speed of the sewing machine, it is only necessary that the respective operations of the forward and backward movement of the plunger 43 have been completed.
A predetermined time is counted by the timer, and if the counted time is a movement time for the plunger 43 to be pulled or returned in advance, the operation of the plunger 43 is considered to be completed. The use of the timer in this way is less expensive and less costly than using the plunger position detector 5 constituted by a sensor or the like.

In the above embodiment, the upper limit rotation speed and the lower limit rotation speed of the sewing machine are set using all of the cloth thickness detector 8, the pitch detector 9, and the solenoid voltage detector 15. The present invention is not limited to this, and the upper and lower limit rotational speeds A and B including the rotational speed under a predetermined condition may be set using one of these detectors.

Further, in the above embodiment, in order to detect the position of the needle connected to the upper shaft,
A rotation angle detector 12 for detecting an upper shaft rotation angle is provided. Instead, a motor encoder that is directly attached to the sewing machine motor 2 and detects the rotation speed of the sewing machine motor 2 can be easily used. It is also conceivable to provide a detection bar on the needle bar instead of the rotation angle detector 12 and provide a sensor for detecting the position of the detection bar to detect the position of the needle.

The signals detected by the cloth thickness detector 8, the pitch detector 9, and the back tack solenoid voltage detector 15 may be configured to be input to the control circuit 11 from the operation panel.

In this case, setting items using the operation panel include setting items for the cloth thickness of the sewing object to be sewn, setting items for the rotation speed of the sewing machine, and a back tack switch receiving section for the rotation angle of the upper shaft. There are a setting item, a setting item of the cloth feed pitch, a setting item of the operation time of the back tack solenoid 4 from when the operation signal is sent to the end of the operation, a setting item of the voltage sent to the back tack solenoid 4, and the like.

Next, a second embodiment will be described with reference to FIGS.

The second embodiment is different from the first embodiment in that it is determined whether or not to change the rotation speed of the sewing machine according to the detection output of the cloth thickness detecting means. In the description of the second embodiment, only the parts that are different from the first embodiment will be described.
Further, the control when the reverse stitching switch is turned on is the same as the control when the reverse stitching is turned off, and thus the control when the reverse stitching is turned off is omitted.

In the second embodiment, in FIG.
If the sewing machine is rotating in step S2, the process proceeds to step S4a.

In step S4a, it is compared whether the cloth thickness set by the cloth thickness detector 8 is smaller than a predetermined value, for example, 3.0 mm. When the cloth thickness is smaller than 3.0 mm, the process proceeds to step S4b, and when the cloth thickness is 3.0 mm or more, the process proceeds to step S5 to detect the solenoid voltage.

In step S4b, the rotational speed detecting means 1
Sewing machine rotation speed (drive rotation speed) by 2 outputs
Is detected, and the rotation speed of the sewing machine becomes lower than a predetermined value, for example, 10
If it is more than 00 rpm (this numerical value can be set differently depending on the cloth thickness and material), step S
Go to Step 3 and if less than 1000 rpm Step S8
Proceed to.

In FIG. 10, the time required for the needle 61 to move from the top dead center position to a position immediately before piercing the cloth 62 is represented by X.
From this position, the tip of the needle penetrates the cloth 62 and the needle plate 6
The time required to reach the upper surface of the third needle hole 64 was W seconds.

In the second embodiment, when the cloth thickness is smaller than 3 mm and the rotation speed of the sewing machine is 1000 rpm or more, the back tack solenoid is turned on and off without any restriction when the back tack switch is pressed. This is because the rotation speed of the sewing machine is 1000 rpm or more and the cloth thickness is 3
mm, the time Wa seconds from immediately before the tip of the needle pierces the cloth to the time when the needle penetrates the cloth is smaller than the back tack solenoid operating time Z seconds (Wa <Z), so that the cloth is horizontally moved by the back tack solenoid. Also, the angle at which the needle pierces the cloth is within a predetermined inclination angle, and sewing can be performed almost vertically.

On the other hand, when the cloth thickness is smaller than 3 mm,
When the rotation speed of the sewing machine is less than 1000 rpm, W
a '> Z. For this reason, in step S8, the back tack switch is received only within a predetermined angle range (back tack switch receiving section) of the upper shaft, and the back tack solenoid operation is completed before the needle pierces the cloth (during X seconds). I have.

In the second embodiment, in addition to the effects of the first embodiment, for example, when the cloth thickness is 3 mm or less, the back tack switch is accepted without changing the rotation speed of the sewing machine. When the cloth thickness is 3.5 mm and the rotation speed is 2000 rpm, the sewing machine rotation speed is set to 500 rpm.
After decelerating to m, the back tack switch is accepted. As described above, since it is determined whether to change the rotation speed of the sewing machine in accordance with the thickness of the cloth, the productivity of high-mix low-volume production is significantly increased.

Further, the cloth thickness detector 8 according to the first and second embodiments can detect the thickness of the workpiece by detecting the amount of lowering of the presser foot. Instead of
For example, it is conceivable to provide a selection switch for selecting a cloth thickness and a cloth type, and to input a cloth thickness and a cloth type for each sewn product and control the sewing machine based on the input signal.

[0109]

According to the control device for reverse stitching of the sewing machine according to the first aspect of the present invention, even if the cloth feeding direction is changed during the rotation of the sewing machine, the needle penetrates the cloth substantially vertically in the cloth. The thread can be sewn almost vertically in the fabric even when the thickness of the fabric to be sewn is increased without causing the thread to be drawn in the fabric.

According to the control device for reverse stitching of the sewing machine according to the second aspect of the present invention, the same effect as that of the first aspect of the invention can be obtained, and the speed of the sewing machine changed to the predetermined speed can be reduced. Since it increases after the operation of the driving member is completed, the speed of the sewing machine becomes the predetermined speed only when changing the feed direction of the cloth feed based on ON / OFF of the reverse stitching switch, and the cycle time of the reverse stitch can be shortened. it can.

According to the control device for reverse stitching of the sewing machine according to the third to sixth aspects of the present invention, reverse stitching can be performed at a suitable speed based on the detection output from each detecting means. The cycle time can be shortened.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a sewing machine to which a reverse stitch control device according to the present invention is applied.

FIG. 2 is a block diagram of a control box in FIG. 1;

FIG. 3 is a flowchart illustrating control when a reverse stitch switch is turned on in the sewing machine to which the present invention is applied.

FIG. 4 is a flowchart illustrating a control of the sewing machine when the reverse feed stitching switch is turned off, in combination with the flowchart of FIG. 3 in the sewing machine.

FIG. 5 is a timing chart for explaining the operation of the reverse stitching control device of FIG. 1;

FIG. 6 is a schematic side view of a cloth feeding unit that changes a cloth feeding direction by a back tack solenoid.

FIG. 7 is a schematic plan sectional view of a back tack solenoid.

FIG. 8 is a flowchart of a subroutine of step 7 in the flowchart of FIG. 3;

FIG. 9 is a flowchart illustrating control when a reverse stitch switch according to the second embodiment is turned on.

FIG. 10 is a view for explaining the relationship between the cloth and a needle penetrating the needle hole.

FIGS. 11A and 11B are diagrams illustrating a seam formed by inserting a needle into a cloth when the cloth feeding direction is reversed; FIG.
Is a seam provided when the needle enters perpendicularly to the fabric, and (b) is a seam formed by inserting the needle obliquely.

FIG. 12 is an explanatory diagram showing the operation of the back tack solenoid and the timing of the hand.

FIG. 13 is a timing chart for explaining a conventional back tack switch reception section and operation timing of the back tack switch.

[Explanation of symbols]

 Reference Signs List 1 sewing machine 2 sewing machine motor 4 back tack solenoid 5 plunger position detector 6 back tack switch 8 cloth thickness detector 9 pitch detector 10 control box 11 control circuit 12 rotation angle detector 15 solenoid voltage detector 52 cloth feed unit

Claims (6)

[Claims] 1. A sewing machine comprising: a pedal for commanding a sewing machine speed in accordance with a stepping operation; a reverse stitch switch for generating a signal for instructing the cloth feeding direction to be reversed by an operation; and a drive member which is electrically operated. A feed conversion means for changing the cloth feed direction to a reverse direction or a forward direction by driving the sewing machine, in a reverse stitch control device of the sewing machine, a rotation angle detection means for detecting a rotation angle of a main shaft of the sewing machine, and a speed of the sewing machine. Speed detecting means for detecting, based on the operation of the reverse stitching switch, changing the speed of the sewing machine to a predetermined speed, and, at a timing included in a rotation angle range of a predetermined upper shaft, the driving member of the feed conversion means. A reverse-sewing control device for a sewing machine, comprising: control means for driving; 2. The sewing machine according to claim 1, wherein when the driving of the driving member for changing the cloth feeding direction is completed, control is performed so as to return from the predetermined speed to a speed of a pedal command. Reverse stitch control device. 3. The apparatus according to claim 1, further comprising a pitch detection unit configured to detect a cloth feed pitch, wherein the control unit sets the predetermined speed based on an output of the pitch detection unit. Sewing machine reverse stitch control device. 4. A cloth thickness detecting means for detecting a cloth thickness, wherein the control means, based on an output of the cloth thickness detecting means,
The reverse sewing controller according to claim 1, wherein the predetermined speed is set. 5. The apparatus according to claim 1, wherein the feed conversion means is an electromagnetic solenoid, and further comprises a solenoid voltage detection means for detecting an amount of voltage applied to the solenoid, and the control means, based on an output of the solenoid voltage detection means, The reverse sewing controller according to claim 1, wherein a predetermined speed is set. 6. A cloth thickness detecting means for detecting a cloth thickness, wherein the predetermined rotation angle range is varied according to the detection of the cloth thickness detection means, and at a timing included in the varied rotation angle range. A reverse-sewing control device for a sewing machine, further comprising control means for controlling a drive member of the feed conversion means to operate.