JPH04146793A - Fabric feed control device for sewing machine - Google Patents

Abstract

PURPOSE:To obtain good thread tension, neither needle thread tension nor bobbin thread tension, by providing a control means exciting an actuator to drive a fabric feed system via the timing command from the second timing sensor when a judging means judges the rotation of a main spindle by the manual rotation of a hand pulley. CONSTITUTION:When the rotation signal is obtained from a rotation sensor 79 detecting the rotation of a sewing machine motor 32, a judging means 75 judges that a main spindle 24 is driven by the sewing machine motor 32. When no rotation signal is obtained from the rotation sensor 24 and only the timing signal from the second timing sensor 88 is fed to a CPU 94, the judging means 75 judges that the main spindle 24 is driven by the manual rotation of a hand pulley 25. An I/O interface 84 is connected to a control means 77 controlling the drive of a fabric feed system 48 via a bus 69. Stable thread tension is obtained at any feed quantity and sewing speed, and beautiful seams can be formed.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a cloth feed control device for a sewing machine, and more specifically, the present invention relates to a cloth feed control device for a sewing machine. In a sewing machine having a directly driven cloth feed mechanism, the cloth feed control allows the workpiece cloth to be fed at an appropriate timing and achieves good thread tension even when sewing is performed by manually rotating the hand pulley. It is related to the device.

Conventional technology In sewing machines that perform straight stitches, zigzag stitches, and various other pattern stitches, the cloth feed mechanism that moves the feed dog back and forth to feed the workpiece cloth in the desired direction is implemented using a stepping motor that is separate from the main shaft drive motor. A directly driven sewing machine has been proposed, for example, in Japanese Patent Laid-Open No. 139694/1983.

Furthermore, as shown in Japanese Patent Application Laid-Open No. 63-105790, a pair of engaging bodies are used to restrain and release the upper thread in the thread path from the thread spool to the thread take-up at a predetermined timing in synchronization with the rotation of the upper shaft. A sewing machine has also been proposed that is equipped with a thread passage control device that controls the approach and separation of the engaging body, and is capable of obtaining good automatic thread tension of the upper thread.

Therefore, by combining the cloth feeding mechanism that is directly driven by the stepping motor, a pair of engaging bodies, and a thread passage control device, a sewing machine that can sew multiple patterns and also has automatic upper thread tension can be realized. will be done. By the way, in the sewing machine according to the above combination, the timings of vertical movement of the thread take-up and sewing needle, binding and release of the needle thread, and fabric feeding are as follows.
No matter what amount the fabric is fed, it is executed at a predetermined rotational phase in synchronization with the rotation of the upper shelf. However, since the stepping motor that drives the cloth feeding mechanism is rotated by pulses of a constant frequency, when the cloth is fed at a predetermined rotational speed of the upper shaft, the end time of cloth feeding is determined by the processing cloth. The larger the feed amount is, the slower it becomes.

For this reason, when the feed amount of the work cloth is large (for example, 4+i
m or more), part of the cloth feeding operation is performed during the upper thread release period, and therefore the upper thread is sufficiently tightened in conjunction with the feeding operation and the lifting operation of the thread take-up while being restrained by the engaging body. . After the engaging body releases the needle thread, the amount of thread necessary for forming the next stitch is let out from the thread spool, and good thread tension is obtained.

However, if the feed amount is small, as shown in Figure 9, the feeding operation ends with the upper thread being restricted, which causes the upper thread to be tightened too much, resulting in an extremely poor quality of the stitches. There is. Furthermore, when the rotational speed of the upper shaft is lower than the medium speed, it is pointed out that there is a problem in that the quality of the stitches deteriorates regardless of the feed amount.

As a solution to this problem, the present applicant came to propose the invention related to Japanese Patent Application No. 1-34201. This is a sewing machine that combines the cloth feeding mechanism directly driven by the above-mentioned stepping motor, a pair of engaging bodies, and a thread passage control device. In response to the output from and the data from the stitch pattern data storage means, part of the work cloth transfer is executed during the upper thread release period by the surface engaging body, and the larger the cloth feed amount, the more the transfer operation start timing becomes. The apparatus includes a timing determining means for determining the start timing so as to have an earlier start time, and a command means for instructing the feed control means to start transferring the work cloth at the start timing determined by the timing determining means.

Problems to be Solved by the Invention As described above, in the sewing machine according to the above-mentioned application, a factor for determining the timing to start transferring the work cloth is determined from the output from the rotational phase detection means, and a good thread tension is automatically obtained by this. It is composed of

However, the rotational phase detection means for the upper shaft is provided on the rotating shaft side of the main shaft driving motor, and the motor and the upper shaft are connected so as to be able to be engaged and disengaged by a clutch built into the sewing machine. Therefore, when the operator manually rotates the hand pulley to sew, the clutch is activated and the mechanical connection between the upper shaft and the sewing machine motor is released, and the upper shaft rotates, but the rotation phase detection means on the motor side is kept inactive.

Therefore, when the hand pulley is turned by hand, no output is obtained from the rotational phase detection means, making it impossible to determine the timing to start transferring the workpiece cloth.

Therefore, in the sewing machine, if the feed of the work cloth is started immediately without timing the cloth feed, the cloth feed operation ends before the pair of engaging bodies are released, and therefore, the cloth feed operation ends before the pair of engaging bodies are released. The problem is that the tension of the thread becomes excessively strong, leading to upper thread tension, which makes it impossible to obtain good automatic thread tension.

In addition, in a sewing machine that is not equipped with the automatic thread tension device consisting of the pair of engaging bodies and the thread passage control device, but is equipped with a numerical dial-type thread tension disc, the thread take-up lever is placed at the highest point, as shown in FIG. If the cloth feeding ends before reaching the point, the upper thread will be paid out by that amount. Then, when the thread take-up reaches its highest point, the upper thread is further unwound. The reason is that the thread clamping force by the dial type thread tension disc is.

This is because the thread clamping force is not as strong as that of the thread pressing V roller of the automatic thread tension device. Therefore, with the dial type thread tension disc, contrary to the case of an automatic thread tension device, there is a problem that the lower thread tension becomes poor as a result of excessive upper thread being paid out.

OBJECTS OF THE INVENTION As mentioned above, the present invention is inherent in a sewing machine of the type that allows an operator to manually rotate a hand pulley to perform sewing as necessary, and that has a cloth feeding mechanism that is directly driven by a required actuator. This invention has been proposed in order to suitably solve the drawbacks of the above-mentioned hand pulley, and to obtain good thread tension by making it possible to feed the work cloth at an appropriate timing when sewing is carried out by hand-turning the hand pulley. The purpose of the present invention is to provide a cloth feeding control device that can perform the following functions.

Means for Solving the Problems In order to overcome the above problems and achieve the intended purpose, the present invention provides a hand pulley that allows rotation of the main shaft by hand rotation by an operator, and a sewing needle, and a sewing machine motor that rotates the main shaft through the main shaft. A needle bar that is reciprocally driven up and down, a thread take-up that is driven reciprocally by the sewing machine motor in synchronization with the needle bar, and a thread take-up that is installed in the thread path from the needle thread supply source to the take-up thread, and that is installed in the thread path from the needle thread supply source to the thread take-up, A sewing machine comprising: a thread tension applying means for applying a thread tension; a cloth feed mechanism that transfers the work cloth to the needle bar using a feed dog when the needle bar is approximately adjusted; and an actuator that directly drives the cloth feed mechanism. a first timing sensor that determines the timing to start cloth feeding to the actuator of the cloth feeding mechanism when the hand pulley is being driven by the sewing machine motor; a second timing sensor for feeding an actuator of the feed mechanism;

Discriminating means for determining whether the main shaft is driven by a sewing machine motor or by manually turning the hand pulley.

and a control means for energizing the actuator to drive the cloth feeding mechanism in response to a timing command from the second timing sensor when the determination means determines rotation of the main shaft by hand turning of the hand pulley. Features.

According to the present invention, when the main shaft rotates, the determining means determines whether the rotation of the main shaft is caused by the sewing machine motor or by the operator manually turning the hand pulley. Determine whether or not. If it is determined that the main shaft is being driven by the sewing machine motor, the first timing sensor gives timing to start cloth feeding to the actuator of the cloth feeding mechanism. Further, when the determining means determines that the main shaft is rotated by hand-turning the hand pulley, the second timing sensor gives timing to start cloth feeding to the actuator of the cloth feeding mechanism.

Embodiment Next, a preferred embodiment of the cloth feed control device for a sewing machine according to the present invention will be described below with reference to the accompanying drawings.

(Regarding the needle bar drive system) In FIG. 2, reference numeral 10 indicates an electronically controlled pattern sewing machine, and the head 14 of the arm portion 12 extending to the left
A support body 18 is pivotally supported on the inner machine frame via a pin 16 so as to be able to swing left and right by a required central angle, and a needle bar 22 having a sewing needle 20 at its lower end is movably raised and lowered on the support body 18. It is arranged. A main shaft 24 extends horizontally in the arm portion 12, and a fourth main shaft 24 extends horizontally.
As shown in the figure, it is rotatably supported on a bushing metal 15. A needle bar lifting crank 26 is connected to the left end of this main shaft 24 via a mechanism that will be described later with reference to FIG.
The crank 26 is connected to a needle bar holder 28 disposed on the needle bar 22.
is connected to. Further, a hand pulley 25 for manual rotation by the operator is fixed to the right end of the main shaft 24 extending outward from the sewing machine.

A sewing machine motor 32 is disposed below the pillar portion 30, and the rotation of the motor 32 is transmitted to the main shaft 24 via a timing belt 34 and a timing pulley 36.

Therefore, when the sewing machine motor 32 is driven, the main shaft 24 rotates in a desired direction, and the needle bar 22 is rotated through the crank 26.
is given vertical motion. A clutch mechanism 27 is interposed between the main shaft 24 and the timing pulley 36, and when the hand pulley 25 is operated, the clutch mechanism 27 operates to mechanically connect the main shaft 24 and the timing pulley 36. is now being released. Therefore, when the operator turns the hand pulley 25 by hand, the main shaft 24 rotates without receiving any load from the sewing machine motor 32.
Can be sewn onto processed fabrics.

(Regarding the needle bar swing mechanism and presser foot) Also, the pillar section 30
The sector gear 38 pivoted to.

It meshes with a pinion 42 of a stepping motor 40 for swinging the needle bar, and drives it to swing left and right at a required central angle. This sector gear 38 is connected to the support body 18 via the illustrated connecting rod 44. Therefore, when the stepping motor 40 is rotated in the forward and reverse directions, the support body 18 and the needle bar 22 move as the sector gear 38 swings.
It is driven to swing left and right via the connecting rod 44.

At the rear of the needle bar 22 in the head 14, a presser foot 11 is provided parallel to the needle bar 22 so as to be able to rise and fall freely, and a presser foot 9 is provided at the lower end of the presser foot 11.
9 is detachably attached.

The presser bar 11 is switched between a raised position and a lowered position by operating an operating lever 13 shown in FIG.

(Regarding the balance mechanism) As shown in FIG. 4, a sub-shaft 17 is rotatably supported inside the arm portion 12 in parallel with the main shaft 24. One end of a swing lever 19 is rotatably connected to the subshaft 17, and the swing lever 19 extends toward the left end surface of a balance crank 21 fixed to the main shaft 24. As shown in FIG. 3, a crank pin 23 protruding from the balance crank 21 is slidably inserted into a cam hole 29 formed in the swing lever 19 to give the lever 19 the required cam movement. It looks like this. A balance 98 is integrally formed on the upper part of the swing lever 19.

A thread holding portion 98a is formed at the upper end of the thread take-up 98. A connecting plate 31 is fixed to the left end of the crank pin 23, and a pivot pin 33 extends leftward from the connecting plate 31.
The above-mentioned needle bar raising/lowering crank 26 is rotatably connected to the needle bar.

The cam hole 29 of the swing lever 19 is, in particular, an arcuate hole that has the same radius as the rotation locus of the crank pin 23 and allows the pin 23 to rotate approximately 74 degrees from the vicinity of the uppermost position, as shown in FIG. 29a, and straight holes 29b extending from both ends of the circular arc hole 29a. Therefore, when the crank pin 23 rotates around the main shaft 24, the swing lever 19 moves between the uppermost position (maximum system pickup position) shown by the solid line in FIG. It is reciprocated up and down between the lowest position (maximum system relaxation position) shown in . Further, by the rotation of the crank 26, the needle bar 22 is driven up and down in a reciprocating manner in synchronization with the rotation of the main shaft 24.

Note that the balance 98 is held at the uppermost position from the time when the phase of the main shaft 24 is approximately 40'' until the eye of the sewing needle 20 reaches the upper surface of the throat plate 35. Therefore, during approximately the second half of the cloth feeding operation. , the thread take-up 98 is held at the uppermost position, and the upper thread 3
7, the maximum amount taken up by the system is ensured by the balance 98.

(About Cloth Feed Mechanism) In FIG. 2, the bed portion 46 is provided with a feed mechanism 48 that operates approximately in synchronization with the needle bar 22, and has a feed dog that feeds the work cloth (not shown) in the vertical and front-back directions. 50 is connected to this. The feed mechanism 48 basically consists of a feed table 52 that supports the feed dog 50, a vertical feed shaft 54 that gives the feed table 52 vertical movement, and a horizontal feed shaft 56 that gives the feed table 52 back and forth movement. configured. For example, the feed table 52 has a fork 52a formed at its front end, and a 1-shaped portion 52b formed at its rear end. The vertical feed shaft 54 is
An arm 58 is pivotally supported on the front side of the bed portion 46 so as to be able to swing around an axis, and is fixed to the feed shaft 54 and extends in an orthogonal direction. ing. Further, the horizontal feed shaft 56 is pivotally supported on the rear side of the bed portion 46 so as to be able to swing freely around the axis, and two arms 62, 62 extending from the feed shaft 56 in a perpendicular direction are attached to one of the feed bases 52. The character portion 52b is pivotally attached.

A swing shaft 64 that can swing freely around the shaft is disposed on the rear side of the vertical feed shaft 54, and a cam 66 fixed to the swing shaft 64 is connected to a cam 66 provided in a direction perpendicular to the vertical feed shaft 54. Crotch arm 6
8 is engaged. This swing shaft 64 is connected to a crank portion 24a formed on the main shaft 24 via a round door 0. Therefore, when the sewing machine motor 32 is driven, the main shaft 24 rotates and gives vertical motion to the needle bar 22, and the swing shaft 64 swings and rotates via the rod 70, and the cam 6
The feed dog 50 is driven vertically along the route 6→bifurcated arm 68→vertical feed shaft 54→feed table 52.

Further, a sector gear 72 is fixed to the right end of the horizontal feed shaft 56, and this sector gear 72 meshes with a pinion 76 of a feeding stepping motor 74 provided on the pillar portion 30. By driving the feeding stepping motor 74 in synchronization with the vertical movement of the feeding dog 50,
The feed dog 50 is driven forward and backward in its raised and lowered positions, respectively.

(Regarding the automatic thread tension device) The sewing machine of this embodiment includes an automatic thread tension device that includes a pair of engaging bodies that restrain and release the upper thread 37 and a thread passage regulating device. For example, in FIG. 4, the needle bar lifting crank 26
Immediately to the left of the main shaft 24 is a plate member 39 that forms part of the machine frame.
It is set perpendicular to. Further, at a position slightly forward of the main shaft 24 and on the left side of the plate member 39, a britension device 41 that provides passage resistance to the needle thread 37 is disposed. The britension device 41 includes a known thread tension disc 41a that provides a required thread passage resistance to the upper thread 37, but this may be omitted.

Of the needle thread supply path from the thread spool (not shown) to the eye of the sewing needle 20, the needle thread 37 from the thread spool to the thread holding portion 98a of the thread take-up lever 98 is restrained in synchronization with the movement of the main shaft 24. As shown in FIGS. 3 to 6, the mechanism for closing and releasing the thread is provided with a pair of engaging bodies 43 and 47 and a thread passage regulating device 45 that drives the engaging bodies between the approaching position and the separating position at a predetermined timing. It is being As shown in FIG. 6, a thread path regulating plate 43 is fixed to the left side of the plate member 39, and the lower ends of the movable plate 47 and the link arm 49 are attached to the plate member 39 by a stepped screw 5.
1 and are rotatably connected to a common pivot.

This movable plate 47 is located near the left of the yarn path regulating plate 43,
A movable wheel 53 rotatably supported on this is the yarn path regulating plate 43.
abuts against the regulating portion 43a from below.

The needle thread 37 can be pinched and restrained between them.

That is, as shown in FIG. 3, one end 47b of the movable plate 47
is connected to a tension spring 55 fixed to the machine frame and is elastically biased, pressing the movable ring 53 against the regulating portion 43a.

Further, the contact shaft 57 provided on the arm portion 47a of the movable plate 47 rests in contact with the lower contact portion 49a of the link arm 49. Note that an annular V-groove 53a is formed on the circumferential surface of the movable ring 53.

The regulating portion 43a engages with the V-groove 53a of the movable ring 53 from above (FIG. 6).

The upper thread 37 that has passed through the britension device 41 is bent into a U-shape at the regulating portion 43a of the thread path regulating plate 43, and reaches the top #98.
It extends to the sewing needle 20 via the thread holding portion 98a. The needle thread 37 bent by the regulating portion 43a is held between the regulating portion 43a and the V-groove 53a at two points and is strongly restrained. In particular, since the movable wheel 53 is driven in a direction parallel to the plane including the thread supply path of the needle thread 37 bent by the regulating portion 43a, and the needle thread 37 is clamped and restrained across the needle thread 37, the needle thread 37 is
The surface pressure that holds them together becomes sufficiently large. In other words, the movable wheel 53
Even when the pressing force is small, the upper thread 37 can be strongly restrained.

In order to synchronize with the rotation of the main shaft 24 and drive the movable wheel 53 pivoted on the movable plate 47 up and down to release and restrain the upper thread 37 at a predetermined timing, as shown in FIGS.
As shown in the figure, the main shaft 24 is located close to the right end of the sub-shaft 17.
A rotating cam 59 fixed to the front face is facing. This rotating cam 5
9 is formed with an elliptical cam groove 61, and the contact 63a of the first arm 63 fixed to the countershaft 17 is inserted into the cam groove 61.
is engaged in. Further, a second arm 65 shown in FIG. 3 is fixed to the left end of the countershaft 17, and a pin 65a protruding from the lower end of the arm 65 is inserted into a loose pin hole 49b drilled at the upper end of the link arm 49. Fitted and connected.

In the pair of engaging bodies 43, 47 and the thread passage regulating device 45 having the above configuration, when the rotary cam 59 rotates together with the main shaft 24 and the first arm 63 swings through the elliptical cam groove 61, the sub-shaft The second arm 65 swings via 17. Then, when the second arm 65 swings, the pin 65a
Due to the cooperation between the link arm 4 and the loose pin hole 49b,
9 swings around a stepped screw 51. As a result, the contact shaft 5 in contact with the lower contact portion 49a of the arm 49
7 is pushed forward, and the movable plate 47 rotates against the spring force of the tension spring 55. Therefore, the movable ring 53
3a, and the upper thread 37 is released from the restrained state.

Further, when the contact portion 49a of the link arm 49 moves backward,
The movable plate 47 is rotated by the restoring elasticity of the tension spring 55, and the movable ring 53 comes into contact with the restriction part 43a again, and the needle thread 37 is restrained between the restriction part 43a and the movable ring 53. in this way,
The upper thread 37 is released and restrained at predetermined timings. The timing at which the upper thread 37 is released or restrained is shown by a curve MC in FIG.

As is clear from FIG. 10, when the thread take-up lever 98 is tightening the needle thread 37 as it rises from the lowest position to the highest position, the needle thread 37 is restrained by the thread path regulating plate 43 and the movable ring 53, so that the needle thread 37 tightening will definitely be carried out. Furthermore, when the thread take-up 98 reaches the uppermost position and tightening of the upper thread 37 is completed, the upper thread 37 is supplied in conjunction with the cloth feed, so that the restriction by the thread path regulating plate 43 and the movable ring 53 is released. , the required amount of needle thread 37 is supplied from the thread spool toward the thread take-up 98. In this way, cloth feeding and needle swinging are completed with the upper thread 37 released, and by the time the sewing needle 20 reaches the throat plate 22, the upper thread 37 is restrained again, and the upper thread 37 is in a restrained state. The sewing operation is performed in , and a thread loop is formed on the bobbin thread bobbin side. Therefore, the necessary amount of needle thread 37 consumed for cloth feeding and needle swinging is reliably supplied, and since the needle thread 37 is restrained when forming the thread loop, unnecessary needle thread 37 is not supplied. There isn't.

(Regarding the first timing sensor) As shown schematically in FIG. 2, the rotating shaft of the sewing machine motor 32 is configured to control the cloth feeding start timing when the main shaft 24 is driven by the motor 32. A first timing sensor 78 is provided which feeds the 48 stepping motors 74. That is, a disc 80 with one slit in the radial direction is provided on the motor rotation shaft,
A photo interrupter 82 is placed across this slit disk 80.
is installed. The slit disk 80 is connected to the sewing machine motor 32 when the main shaft 24 is rotationally driven by the sewing machine motor 32.
The main shaft 2 rotates together with the main shaft 2 by manual operation of the hand pulley 25.
4, the motor side is separated by the clutch mechanism 27, so the disc 80 does not rotate. The photointerrupter 82 detects the light passing through the slit when the rotational phase of the slit disk 80 and the main shaft 24 make about 360°, and sends the CPU 94 shown in FIG.
2 provides a timing signal regarding the current position.

(Regarding the second timing sensor) As shown in FIG. 2, the sewing machine 10 is equipped with a second timing sensor that provides timing for starting cloth feeding to the stepping motor 74 of the cloth feeding mechanism 48 when the hand pulley 25 is being turned by hand. 88 are provided. For example, spindle 2
4 is provided with a disk 90 having one slit in the radial direction, and a photointerrupter 92 is provided with the slit disk 90 interposed therebetween. This photointerrupter 92 detects light passing through the slit when the rotational phase of the slit disk 90 and the main shaft 24 is approximately 360°,
A timing signal regarding the current position of the needle bar 22 is supplied to the CPU 94 shown in FIG.

Since this slit disk 90 is provided on the main shaft 24, it rotates both when the main shaft 24 is rotated by the sewing machine motor 32 and when it is rotated by the hand pulley 25, so that the current position of the needle bar 22 is outputs a timing signal related to For this reason, the sewing machine motor 32
During normal sewing in which the timing sensor 78 is driven, signals are output redundantly from the first timing sensor 78 and the second timing sensor 88. Therefore, in this case, the first
A process is performed in the control circuit in which the signal from the timing sensor 78 is used with priority over the signal from the second timing sensor 88.

(Regarding the Control Circuit of the Sewing Machine) Next, the control system of the sewing machine 10 will be described with reference to the block diagram shown in FIG. A pattern input device 97 is connected to the I10 interface 84 of the control circuit C, and the first timing sensor 78 and second timing sensor 88 . A rotation sensor 79 that detects the rotation of the sewing machine motor 32 is also connected.

Further, the sewing machine motor 32 is connected to the I10 interface 84 via a drive circuit 96, the needle bar swinging stepping motor 40 is connected to a drive circuit 81, and the feeding stepping motor 74 is connected to a drive circuit 67.

The machine/○ interface 84 also contains other elements necessary to operate the sewing machine 10, such as starting and starting the sewing machine 10.
Start/stop switch for selectively commanding stop, main shaft 24
A speed detector for detecting the rotational speed of the needle bar 22, a volume for adjusting the amount of swing of the needle bar 22, a volume for adjusting the amount of feed of the workpiece cloth, and a clock pulse generating means for synchronizing each movable part are provided. , illustration and description thereof will be omitted.

The engineering/○ interface 84 is connected to the CPU 94, ROM 71, RAM 73, etc. via a bus 69. This ROM 71 stores pattern data in which needle position data, that is, feed amount data and needle swing data for each stitching operation is stored for each of a large number of patterns such as characters and symbols, and also stores selected stitch pattern data. A control program is stored that controls the feeding stepping motor 74 based on the feeding amount data when reading and receiving a feeding start signal. The ROM 71 also stores a control program for controlling the driving of the sewing machine motor 32, a control program for controlling the start of the cloth feeding operation for determining the start timing of the cloth feeding operation based on the feed amount data and the speed signal, and the like. Further, the RAM 31 includes various types of memories that temporarily store the results of arithmetic processing performed by the CPU 94.

Further, the I10 interface 84 is connected to the determining means 75 via a bus 69. This determining means 75
is provided to determine whether the main shaft 24 is driven by the sewing machine motor 32 or by manually turning the hand pulley 25. for example,
The rotation sensor 79 detects the rotation of the sewing machine motor 32
When the rotation signal is obtained from the
It is determined that the main shaft 24 is driven by the sewing machine motor 32. Further, if the rotation signal from the rotation sensor 79 is not obtained and only the timing signal from the second timing sensor 88 is supplied to the CPU 94, the main shaft 24 is driven by hand-turning the hand pulley 25. The determining means 75 makes the determination.

The I10 interface 84 is also connected via a bus 69 to a control means 77 for controlling the driving of the cloth feeding mechanism 48 . This control means 77 controls the discriminating means 7.
5 is provided for energizing the stepping motor 74 in response to a timing command from the second timing sensor 88 and driving the cloth feeding mechanism 48 when the rotation of the main shaft 24 due to hand rotation of the hand pulley 25 is determined.

Effects of the Embodiment Next, the actual use of the cloth feed control device according to the embodiment will be explained. Prior to operation of the pattern stitch sewing machine 10, necessary sewing preparations such as thread hooking are performed. In other words, the needle thread 37 drawn out from a thread supply source (not shown) passes through the britension device 41 and then passes through the automatic thread tension device. The thread is bent into a U-shape by the regulating portion 43a of the thread path regulating plate 43, passes through the thread holding portion 98a of the thread take-up lever 98, and then passes through the eye of the sewing needle 2o. Then, the upper thread 37 is attached to the regulating portion 43 as described above.
a and the V-groove 53a in a releasably manner. The pattern input device 97 is also operated to input a desired pattern to be sewn. Next, when a start/stop switch (not shown) is operated and a start signal is input to the CPU 94,
According to a control program stored in ROM 71, sewing machine motor 32 is driven via drive circuit 96, and main shaft 24 rotates. Also, according to the feed amount data for each wrapping operation stored in the ROM 71, the feeding stepping motor 7
4 is driven via a drive circuit 67, and the feed dog 50 is moved up and down and back and forth. Furthermore, the stepping motor 40 for swinging the needle bar is driven by the drive circuit 81 in accordance with the needle swing data for each sewing operation stored in the ROM 71.
The needle bar 22 is swung in a direction perpendicular to the cloth feeding direction.

By the vertical movement and rocking movement of the needle bar 22 (sewing needle 20) and the vertical movement and back-and-forth movement of the feed dog 5o, which are controlled in advance in this way, the work cloth (not shown) is patterned in various ways according to the stitch pattern data. Since the sewing machine according to the embodiment is equipped with an automatic thread tension device having the above-mentioned structure, the pattern of The larger the feed amount and the rotational speed of the main shaft 24, the earlier the cloth feeding start timing becomes. For example, the main shaft 24
When the rotational speed of is constant, as the feed rate increases,
Cloth feeding starts early.

Further, when the feed amount is constant, as the sewing speed increases, the cloth feed start timing becomes earlier.

In other words, in the first half of any cloth feeding operation, the upper thread 37 is restrained by the thread path regulating plate 43 and the movable shaft 53, so that the upper thread 37 is moved in conjunction with the feeding operation by the feed dog 50 and the lifting operation of the thread take-up lever 98. Thread 37 is sufficiently tightened.

In addition, during the period in which the upper thread 37 is released, the second half of the cloth feeding operation is executed, so the upper thread 37 is moved to the thread spool by the amount of thread necessary for forming the next stitch in conjunction with the feeding operation. is supplied to the balance 98 from Furthermore, by the time the sewing needle 20 reaches the throat plate 35, the upper thread 37 is again restrained, and the sewing operation is performed with the upper thread 37 restrained.

Therefore, stable thread tension can be obtained at any feed amount and sewing speed, and beautiful stitches can be formed.

Next, the case where the operator manually turns the hand pulley 25 to perform sewing will be described with reference to the flowchart shown in FIG. After starting the sewing machine 10, first in step (hereinafter referred to as "S") 1, the first timing sensor 78
If it is the front foot (YES), the process moves to S2, and it is checked by the rotation sensor 79 shown in FIG. 1 whether the sewing machine motor 32 is rotating. This S
If 2 is R constant (YES), the process moves to S3, and as described in the above-mentioned Japanese Patent Application No. 1-34201, a timer is set in S4 based on the speed signal from the speed detector. and S
When the timer times up in step 5, the process moves to S7.
The stepping motor 74 is driven, and the cloth feeding mechanism 48 feeds the work cloth.

In this case, as described above, the automatic thread tension device consisting of the pair of engaging bodies 43, 47 and the thread passage regulating device 45 operates in a timely manner to restrain and release the upper thread 37, thereby obtaining a suitable thread tension. That's exactly what I did.

Further, if the result of checking in S2 as to whether the sewing machine motor 32 is rotating by the rotation sensor 79 is negative (No), the determining means 75 determines that the manual rotation mode using the hand pulley 25 is set. It is determined. Therefore, the process moves to the next step 86, where it is checked whether the second timing sensor 88 is turned on. If this result is negative (No), even if the operator rotates the hand pulley 25 by hand, the stepping motor 74 will not be driven and the fabric feeding mechanism 48 will not feed the work cloth. Therefore, at this time, the second timing sensor 88
The confirmation in S6 is repeated until the switch is turned ON. and,
Determine whether the second timing sensor 88 is ON in S6 (YES
), the process immediately moves to S7, the stepping motor 74 is driven, and the cloth feeding mechanism 48 feeds the work cloth.

That is, as shown in FIG. 8, when the hand pulley 25 is operated by hand, the cloth feed timing command is issued while the pair of engaging bodies 43 and 47 in the automatic thread tension device are open, so that the upper thread The flaws that lead to poor performance are suitably eliminated. In addition.

In the case of the dial-type thread tension disc mentioned earlier, the cloth feed timing command is issued near the time when the thread take-up lever reaches the top position, which solves the above-mentioned drawback of adjusting the bobbin thread tension. .

Effects of the Invention As described above, according to the fabric feed control device for a sewing machine according to the present invention, in a sewing machine equipped with a fabric feed mechanism that has a hand pulley and is directly driven by a required actuator, the operator can When sewing by turning the hand pulley by hand, the thread tension device can feed the work cloth at the appropriate timing when the upper thread is released, so there is no need to worry about lower thread tension or lower thread tension, resulting in a good sewing machine. There is an advantage that the thread tension can be adjusted.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a control system in which a cloth feed control device for a sewing machine according to the present invention is suitably implemented, FIG. 2 is a schematic configuration diagram of a pattern stitch sewing machine according to the present embodiment, and FIG. 4 is a schematic front view of the internal mechanism shown in FIG. 3; FIG. 5 is a sectional view taken along the line ■-■'' in FIG. Figure 6 shows VI-V in Figure 3.
7 is a sectional view taken along line I, and FIG. 8 is a flowchart when the operator performs sewing by manually turning the hand pulley. A diagram showing the relationship between the cloth feeding operation and the upper thread release period when the hand pulley is turned by hand, No. 9 @ is a time chart of the operation of each mechanism of the sewing machine, and Fig. 10 is the cloth feeding operation according to the prior art. FIG. 11 is a diagram showing the relationship between the movement of the thread take-up and the cloth feed in the dial-type thread adjustment plate according to the same prior art. 24... Main shaft 25... Hand pulley 32
... Sewing machine motor 48 ... Cloth feed mechanism 74 ...
Actuator (pulse motor) 75...discrimination means
77...Control means 78...First timing sensor 88...Second timing sensor Patent applicant Brother Industries, Ltd. Applicant's agent Patent attorney Homare Yamamoto z--H. 1゛ ゞFIG, 1 Control circuit IC FIG, 3 FIG, 4 1〇(1-FIG, 9

Claims (1)

[Scope of Claims] A hand pulley (25) that allows rotation of the main shaft (24) by hand rotation by an operator, and a sewing needle (20), and is reciprocated up and down via the main shaft (24) by a sewing machine motor (32). a thread take-up (98) that is reciprocated by the sewing machine motor (32) in synchronization with the needle bar (22); a thread tension imparting means (43, 45, 47) that is provided in the thread path leading to the upper thread (37) and applies a required thread tension to the upper thread (37);
When the needle bar (22) is approximately adjusted, feed the work cloth to the dog (50).
A cloth feeding mechanism (48) that transfers the cloth by
8), when the main shaft (24) is driven by the sewing machine motor (32), the timing of starting cloth feeding is determined by the actuator of the cloth feeding mechanism (48). (74); and a second timing sensor (78) that provides cloth feed start timing to the actuator (74) of the cloth feed mechanism (48) when the hand pulley (25) is being turned by hand. timing sensor (8
8), a determining means (75) for determining whether the main shaft (24) is driven by the sewing machine motor (32) or by manually turning the hand pulley (25); and this determining means (75) When the rotation of the main shaft (24) due to hand rotation of the hand pulley (25) is determined, the actuator (74) is energized by the timing command from the second timing sensor (88) to operate the cloth feeding mechanism (48).
) A control means (77) for driving a cloth feed control device for a sewing machine.