JPH10235059A - Cloth thickness detecting device for sewing machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To detect a cloth thickness without being influenced by the displacement of a presser bar in a one for detecting the cloth thickness in relation to the rocking of a detecting lever by vertically moving the detecting lever in interlocked with the operation of the presser bar, and supporting it by a support member independent to the vertical chamber of the presser bar by a thickness change. SOLUTION: A U-shaped cloth thickness base 20 is arranged as a support member is arranged so as to nip the lower thickness of the arm part 1a of a frame 1, and a presser bar 6 is inserted vertically through the cloth thickness base 20. A compression spring 63 is interposed around the presser bar 6 between a presser bar guide bracket 50 and the upper part of the cloth thickness base 20, and the cloth thickness base 20 is energized down by the spring force. When a work cloth is advanced into a throat plate 9 and the presser foot 5, a potential operating plate 21 is rotated through a cloth thickness link 23 according to the rotation, and a voltage signal corresponding to the cloth thickness is outputted from a potentiometer through the rotation of a potential contact shaft 25a making contact with the operating plate 21.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cloth thickness detecting device for detecting a cloth thickness.

[0002]

2. Description of the Related Art A cloth is sandwiched between a needle plate and a presser foot provided at the lower end of a presser bar, and the thickness of the cloth is detected by detecting the displacement of the presser bar which moves up and down in accordance with the thickness of the cloth. For example, in a sewing machine described in JP-A-57-59592, which is configured to feed out a necessary amount of yarn based on a cloth thickness,
If the front and rear ends of the presser foot that presses around the needle drop when the cloth has a step, the presser bar is displaced due to the inclination of the presser foot, and the cloth thickness at the needle drop is detected to be thicker than it actually is. Therefore, before and after the step, there is a problem that unnecessarily thread is fed out and sewing failure occurs.

[0003] A solution to such a problem is disclosed in, for example, Japanese Patent Publication No. 2-40354.
This device has a detection lever that has a tip that contacts the surface of the cloth on the needle plate and is urged to the cloth surface by a torsion coil spring, and swings around one axis according to the cloth thickness, A support member that supports this detection lever is fixed to the sewing machine side.

Therefore, the cloth thickness can be detected in relation to the swing of the detection lever without being affected by the inclination of the presser foot, that is, the displacement of the presser bar.

Further, if the support point of the detection lever is located far away from the needle plate, the detection accuracy is reduced. Therefore, the detection lever is provided at an upper position not far from the needle plate. That is, a support member having a support point is fixedly arranged at an upper position not far from the needle plate.

[0006]

However, in the apparatus disclosed in Japanese Patent Publication No. 2-40354, even if the presser foot is raised, only the detection lever pivots upward and separates from the cloth. As such, the support member is fixed,
In addition, since the fixing member is fixed at an upper position that is not far from the needle plate, the supporting member hinders the setting and taking out of the cloth and the replacement of the presser foot.

Accordingly, the present invention can accurately detect the thickness of the cloth without being affected by the displacement of the presser bar at the time of sewing. On the other hand, if the support member is in the way when setting or removing the cloth or replacing the presser foot, the present invention can be used. It is an object of the present invention to provide a sewing machine cloth thickness detecting device capable of improving workability without using the same.

[0008]

According to a first aspect of the present invention, there is provided a sewing machine cloth detecting apparatus, wherein a tip of the sewing machine is in contact with a surface of a cloth on a needle plate, and a single axis is supported according to the cloth thickness. In a sewing machine cloth thickness detecting device capable of detecting the cloth thickness in relation to the swing of the detecting lever, the detecting lever is moved up and down in conjunction with the lifting operation. Further, it is characterized in that the presser bar is pivotally supported by an independent supporting member with respect to a change in lifting and lowering of the presser bar due to a change in cloth thickness.

According to the cloth thickness detecting device for a sewing machine of the present invention, the detection lever is pivotally supported by the independent supporting member against the change of the lifting and lowering of the presser bar. The cloth thickness is detected in relation to the swing of the detection lever without being affected by the displacement of the rod. In addition, since the support member that supports the detection lever is interlocked with the operation of the presser foot, when the presser foot is lifted, the support member rises, and the support member does not disturb the setting and removal of the cloth, and the replacement of the presser foot. Etc. will be performed.

According to a second aspect of the present invention, in order to achieve the above object, in addition to the first aspect, the detection lever is urged against the cloth surface by a compression or tension spring. And

According to the sewing machine cloth detecting device of the present invention, since the detecting lever is urged against the cloth surface by the compression or tension spring, an excessive force is applied to the tip of the detecting lever from below. When acted, it is 2-4035
No. 4, the detection lever is urged to the cloth surface by a torsion coil spring as described in
The force acting on the detection lever escapes favorably.

[0012]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a front configuration diagram showing an overlock sewing machine (two-needle, four-thread lock sewing machine) to which the present invention is applied.

In FIG. 1, reference numeral 1 denotes a sewing machine frame, and a needle bar 4 having left and right sewing needles 2 and 3 at a lower end is attached to an arm portion 1a of the frame 1 so as to be vertically movable. . The needle bar 4 moves up and down in conjunction with the main shaft 13 of the sewing machine. The arm 1a of the frame 1 is also provided with a presser bar 6 having a presser bar clamp 50 and a presser foot 5 at the lower end so as to be vertically movable. The presser bar 6 is urged downward by a presser bar spring (compression spring) 51 provided around the presser bar 6 between the frame 1 and the presser bar holder 50.

An upper looper 7 and a lower looper 8 are provided in the bet portion 1b of the frame 1. The upper looper 7 and the lower looper 8 and the left sewing needle 2 or the right sewing needle 3 cooperate with each other. An overlock stitch is formed on the object to be sewn.

At the upper part of the frame 1, from the left side to the right side in the figure, a feeding part 32 for feeding the needle thread 15 to the left sewing needle 2, a feeding part 33 for feeding the looper thread 17 to the upper looper 7, and a lower looper 8 looper thread 18
Are provided, respectively. These feeding portions 32, 33, and 34 are provided with stepping motors (yarn feeding devices) 36a, 36, respectively.
Since the same mechanism is provided with b and 36c, the configuration will be described with the feeding portion 32 of the left needle thread 15 as a representative.

A stepping motor 36a is fixed to the frame 1. A delivery roller 37 is fixed to an output shaft of the stepping motor 36a. Auxiliary rollers 38 and 39 are opposed to the delivery roller 37, and an auxiliary roller mounting plate is provided. 40 is rotatably mounted. The auxiliary roller mounting plate 40 is rotatably mounted on one end of an auxiliary roller lever 41, and an auxiliary roller spring 42 is hung on the other end of the auxiliary roller lever 41. That is, the auxiliary rollers 38 and 39 are constantly pressed against the feeding roller 37 by the urging force of the auxiliary roller spring 42. A yarn guide 100 is provided in the vicinity of the feeding roller 37, and the needle guide 100 pulls a needle thread (left needle thread 15 in the feeding section 32) drawn from a thread spool (not shown). Feeding roller 37
You will be guided not to get out of the way.

As described above, the feeding portion 3 of the left needle thread 15
When the stepping motor 36a is driven to rotate, the feeding roller 37 and the auxiliary rollers 38 and 3 are driven.
The needle thread 15 is paid out in cooperation with the needle thread 9. The feeding section 33 of the upper looper thread 17 and the feeding section 34 of the lower looper thread 18 have the same configuration.

As shown in FIG. 2, between the feeding portion 32 of the left needle thread 15 and the feeding portion 33 of the upper looper thread 17, a feeding portion 35 for feeding the right needle thread 16 to the right sewing needle 3 is provided. It is arranged. The supply roller 44 of the supply section 35 of the right needle thread 16 does not have a dedicated driving source. That is, the feed roller 44 is connected to the left needle thread 15 via the gears 43a, 43b, and 43c.
Of the left needle thread 1
The right needle thread 16 is paid out by rotating according to the rotation of the feeding roller 37 of No. 5. The mechanism of the auxiliary roller and the like are the same as those described above.

The looper balance 14 has three thread hooks 1
4a, 14b, and 14c.
The lower looper thread 18 described above is hung on 14c,
The above-mentioned upper looper yarn 17 is hung on the yarn hooking portions 14b and 14c. And these thread hooking parts 14a, 14
The b and 14c swing between a position shown by a solid line and a position shown by a dotted line in the figure in conjunction with the main shaft 13 to tighten the upper looper thread 17 and the lower looper thread 18.

In the thread path between the looper balance 14 and the upper looper 7, a thread breakage detecting mechanism 52 for the upper looper thread is provided.
In the yarn path between the looper balance 14 and the lower looper 8, a yarn breakage detecting mechanism 53 for the lower looper yarn is provided. Since the thread breakage detection mechanisms 52 and 53 are the same mechanism, the configuration will be described with the thread breakage detection mechanism 52 for the upper looper thread as a representative.

The detection mechanism 52 comprises a movable portion 56 and a photo sensor (thread break sensor) 55. Movable part 5
As shown in FIGS. 3 and 4, reference numeral 6 includes a spring guide 57 which has a hollow cylindrical shape and has one end closed by a closing plate 57c. The spring guide 57 houses the torsion spring 54 therein and is fixed to the mounting plate 60 by a screw 59 inserted from the closing plate 57c side. The spring guide 57 also has a large cutout 57a formed at the end of the body on the side of the mounting plate 60, and a hole 57b formed in the closing plate 57c. Of the spring 54 protrudes from the hole 57b at the opposite end of the spring 54. On the outer peripheral side of the spring guide 57, a hollow cylindrical shielding body 58, which is prevented from falling out by the shielding plate 57c, is rotatably set. A small notch 58a is formed in the body of the shielding body 58 at a position corresponding to the notch 57a.
The threading end 54a protrudes from 8a. A shielding plate 58b protruding outward is also provided on the body of the shielding body 58.
The photo sensor 55 is provided at a position where the photo sensor 55 can be shielded by the shielding plate 58b.

The threading end 5 of the spring 54
As shown in FIG. 1, a looper thread from the thread hooking portion 14c of the looper balance 14 is hung on 4a,
The looper thread hung on the threading end 54a is
It is passed through the eye of the looper.

Therefore, when the tension of the looper yarn changes,
The threading end 54a of the spring 54 on which the looper thread is hooked and the shielding body 58 rotate, and the photosensor 55 is shielded or opened by the shielding plate 58b.

The needle thread balance 19 is a plate cam on which the above-described left needle thread 15 or right needle thread 16 is hung. The plate cam 19 rotates in conjunction with the main shaft 13 and tightens the needle threads 15 and 16 by the cam shape.

The feed adjusting knob 26 is rotatably attached to the frame 1.
A feed adjusting cam 27 is attached. One end of a feed adjustment link 28 is connected to the feed adjustment cam 27, and the other end of the feed adjustment link 28 is connected to a feed mechanism (not shown). And feed adjustment knob 2
By rotating 6, the amount of horizontal movement of the feed dogs 61 and 62 (see FIG. 4) is adjusted.

An opening is formed in the feed adjusting link 28, and an operating portion of a slide volume (feed set value sensor) 29 attached to the frame 1 is inserted into the opening. Then, a voltage corresponding to the position of the operating portion, that is, a voltage corresponding to the position of the feed adjusting link 28 is output from the slide volume 29, and the feed set value is known.

A fan-shaped shield plate 30a is attached to the main shaft 13 which is belt-linked to a main motor 92 of the sewing machine (not shown in FIG. 1; see FIG. 7). The photosensors 30b are provided at positions where the photosensors 30b can be shielded by the shielding plate 30a. Therefore, when the main shaft 13 rotates, the photosensor 30b is shielded or opened by the shielding plate 30a, and the main shaft 13 is rotated.
Is detected. That is, these shielding plates 30a,
The spindle sensor 30 is constituted by 30a and the photo sensors 30b, 30b.

The upper surface of the bet portion 1b of the frame 1 is shown in FIG.
As shown in FIG. 2, a needle plate 9 is attached. A sub-feed dog 61 is provided below the needle plate 9 on the front side of the needle drop B, and the main feed is provided on the back side of the needle drop B. Teeth 62 are provided. The needle plate 9 has the sewing needles 2 and
In addition to the three needle holes 9a, openings 9b for the main and sub feed dogs 61 and 62 are provided.

Referring back to FIG. 1, an upper knife 10 is attached to an upper knife arm 11 which moves up and down in conjunction with the main shaft 13, and a lower knife 12 is disposed below the upper knife 10. Have been. The lower knife 12 is fixed to a lower knife holder (not shown), and the lower knife holder is attached to the frame 1 so that the position can be adjusted in the left and right directions in the figure. Then, the upper knife 10 and the lower knife 12 that move up and down cooperate to trim the ends of the work cloth fed by the above-described main / sub feed teeth 61 and 62.

Next, the configuration of the cloth thickness detecting device G will be described with reference to FIGS. A U-shaped cloth thickness base (supporting member) 20 is disposed so as to sandwich the lower meat 1c of the arm portion 1a of the frame 1, and the holding bar is provided on the cloth thickness base 20 so as to penetrate vertically. 6 has been inserted. That is, the cloth thickness table 20 is supported by the presser bar 6 so as to be movable in the vertical direction, and the vertical movement range is restricted by the U-shaped portion sandwiching the lower meat 1c.

A cloth-thickness spring (compression spring) 63 is interposed around the presser rod 6 between the presser bar holder 50 and the upper portion 20a constituting the U-shaped portion of the cloth thickness base 20. The cloth thickness table 20 is lowered by the cloth thickness table spring 63 (the needle plate 9).
Side), the upper portion 20a of the cloth thickness base 20 is pressed against the lower meat 1c.

The upper portion 20a of the cloth thickness base 20 is provided with a projection 20b projecting rearward. The projection 20b is loosely fitted in a vertically long guide groove 1d formed in the frame 1. ing. In addition, the presser bar holder 50 also includes a protrusion 50b protruding rearward, and this protrusion 50b also
It is loosely fitted in the guide groove 1d. By inserting the projections 20b and 50b into the guide groove 1d, the rotation of the cloth thickness base 20 and the presser bar holder 50 is restricted. Further, as shown in FIG. 3, the cam portion 64a of the lifting lever 64 is in contact with the lower surface of the protrusion 20b of the cloth thickness base 20.

On the side of the upper portion 20a of the cloth thickness base 20, a potentiometer operating plate 21 is rotatably mounted with a shaft 65 as a fulcrum. The lower portion of the cloth thickness base 20 extends downward,
A cloth contact (detection lever) is provided below the extension portion 20c.
Reference numeral 22 is attached rotatably around a shaft 66. The near side portion of the potentiometer plate 21 and the near side portion of the cloth contact 22 are connected by a cloth thickness link 23.

At the front end of the cloth contact 22 in FIG. 2, a cloth contact portion 22a protruding downward is provided.
The cloth contact portion 22a is formed in the opening 5
a. A tension spring 67 (see FIG. 3) is hung on the potentiometer plate 21.
The tension link 67 urges the cloth thickness link 23 downward, whereby the cloth contact portion 22a of the cloth contactor 22 is pressed.
Is in contact with the work cloth near the region position E on the upper surface of the needle plate 9 (see FIG. 4). The position of the region E is located between the sub-feed teeth 61, 61 and inside the horizontal feed trajectory of the sub-feed tooth 61 as in the present embodiment. Ideal. Then, the cloth contact portion 22a
Is formed in an R shape facing the cloth feeding direction, in which the work cloth is easily guided (the work cloth easily enters).

As shown in FIG. 1, a potentiometer mounting plate 70 is fixed to the arm portion 1a of the frame 1, and the potentiometer mounting plate 70 is raised when a presser described later is lifted. A stopper 71 that contacts the rear end of the potentiometer operating plate 21 is formed. The potentiometer (cloth thickness sensor) 24 is also mounted on the potentiometer mounting plate 70. As shown in FIGS. 1 and 2, a potentiometer contact 25 is fixed to a rotating shaft 24 a of the potentiometer 24, and the potentiometer 25 is eccentric with respect to the rotating shaft 24 a. At the position, a potential contact shaft 25a protrudes. As shown in FIG. 2, a tension spring 68 is hung on the potentiometer 25.
a is always in contact with the potentiometer operating plate 21.

Accordingly, when the work cloth enters between the needle plate 9 and the presser foot 5, the cloth contact 22 rotates according to the cloth thickness, and the cloth link 23 moves up and down with this rotation. With this vertical movement, the potentiometer operating plate 21 rotates, and the potentiometer contact shaft 25a in contact with the potentiometer operating plate 21 rotates the potentiometer 24 with the rotation axis 24a of the potentiometer 24 as an axis. The rotation of the potentiometer 25 follows the rotation of the plate 21 and the rotation of the potentiometer contact 25 causes the potentiometer 24 to move away from the needle drop B by a distance x, that is, the cloth contact portion 22a moves to the work cloth. A voltage corresponding to the cloth thickness of the work cloth at the contact position (cloth thickness detection position) is output.

An input side of a CPU (microcomputer) 80 is connected to the photo sensor (thread break sensor) 55 for outputting thread break information and the spindle sensor 30 for outputting spindle phase information. On the input side of the CPU 80, a potentiometer (cloth thickness sensor) 24 for outputting cloth thickness information is connected via an A / D converter 82, and a slide volume (feed) for outputting feed setting information. (Set value sensor) 29 is connected via an A / D converter 83. Further on the input side of the CPU 80,
A key matrix (stitch selection means) 81 having a start / stop switch for starting / stopping the sewing machine and a pattern selection switch for designating the type of sewing pattern (stitch) is connected.
Input to 0.

On the other hand, the main motor 92 of the sewing machine and the stepping motors 36a and 36 are provided on the output side of the CPU 80.
b and 36c are driving circuits 91, 88a and 88, respectively.
b, 88c.
A drive command is given from 0.

The CPU 80 further has a ROM 9 in which a control operation procedure is stored in the form of a program and fixed data.
3. A RAM 94 for temporarily storing detected data (especially cloth thickness data in the present embodiment), data used for calculation, calculation results, and the like is connected.

The CPU 80 is provided with a predetermined sewing control means (not shown) for executing the left-over-three-thread overlock sewing based on the predetermined input signal. This sewing control means can, of course, execute overlock stitching other than the left-needle three-thread overlock stitching, or a predetermined overlock width such as wide winding stitching, full winding stitching, and decorative stitching.

The CPU 80 is also detected by the cloth thickness sensor 24 based on the distance x (which is known in advance) between the cloth thickness detection position and the needle drop B and the cloth feed amount, and is sequentially stored in the RAM 94. The cloth thickness data at the needle drop B is specified from the cloth thickness data thus obtained, and the cloth thickness data and the key matrix 8 are specified.
The needle thread 15 (16) and the upper looper at a predetermined phase timing from the spindle sensor 30 based on the selected pattern information from the sewing pattern selection switch 1 and the feed setting information (feed pitch) from the feed set value sensor 29. A thread feeding amount acquisition means 80a for individually calculating the thread feeding amounts of the thread 17 and the lower looper thread 18;
From the drive circuits 88a, 88b, and 8 at a predetermined phase timing to feed out the obtained thread payout amount.
8c is provided.

The CPU 80 further includes an inclination judging means 80c for judging the inclination of the cloth based on the cloth thickness data stored in the RAM 94. When a signal indicating that there is an inclination is received, the cloth thickness data at the needle drop B is calculated instead of the cloth thickness data corresponding only to the cloth thickness at the inclined portion.

Further, the CPU 80 determines a yarn break based on a signal from the yarn break sensor 55, and when it is determined that the yarn is broken, a stop command is issued to the stepping motors 36b and 36c corresponding to the looper yarn that has broken. Is provided.

Next, the operation of the overlock sewing machine thus configured will be described below. In the case of performing the three-needle overlock sewing with the left needle, the operator first hooks the left needle thread 15, the upper looper thread 17, and the lower looper thread 18 as shown in FIG.

Then, when the left needle three-thread overlock sewing is selected by the sewing pattern selection switch of the key matrix 81,
An arithmetic expression for calculating the thread feed amount corresponding to the left needle three-thread overlock stitch is read from the ROM 93 to the RAM 94. This arithmetic expression is individually provided for each of the needle thread 15, the upper looper thread 17, and the lower looper thread 18, and the thread delivery amount Q1 of the needle thread 15, the thread delivery amount Q2 of the upper looper thread 17, the lower looper thread The thread feed amount Q3 of No. 18 is expressed by the following equation. Q1 = F + D + A Q2 = F + D + A1 Q3 = F + D + A2 where F is feed pitch, D is work cloth thickness data,
A, A1, and A2 are correction values that change depending on the overlock width, stitch type, and the like.

The cloth thickness data D of the work cloth is obtained from the cloth thickness sensor 24, and the feed pitch F is obtained from the feed set value sensor 29.

Here, when the start switch of the start / stop switch of the key matrix 81 is turned on, the main motor 92 is driven, and the main shaft 13 is rotated.
Overlock stitching with three left needles is started. Then, the work cloth is trimmed by the cooperation of the lower knife 12 and the upper knife 10, and by the cooperation of the left sewing needle 2 and the upper and lower loopers 7, 8,
Overlock stitches will be formed at the ends of the cut and aligned work cloth.

At this time, even if the presser bar 6 moves up and down due to the displacement of the presser foot 5, the cloth thickness table 20 is pressed against the lower meat 1c by the cloth thickness table spring 63.
However, it is not affected by the vertical movement of the presser bar 6.

At this time, from the spindle sensor 30,
1 (a), two phase signals SY as shown in (b)
NC1 and SYNC2 are output. The CPU 80 includes:
When the falling edge a4 (210 °) of SYNC2 is detected, the cloth thickness data D from the cloth thickness sensor 24 and the feed pitch F from the feed set value sensor 29 are read at this timing. Note that 0 ° is the needle top dead center.

Here, the procedure for detecting the cloth thickness data and the procedure for calculating the thread payout amount using the cloth thickness data will be described below with reference to the flowchart shown in FIG. First, when the edge a4 (210 °) is detected as the phase in which the feed dogs 61 and 62 are lowered (Step 1), the cloth thickness data is read by the cloth thickness detecting device G (Step 2), and the cloth thickness stack (RAM 94) is read. ) the fabric thickness data stores as the latest fabric thickness data P ₀ (step 3). In this fabric thickness stack, as shown in FIG. 9, every time new fabric thickness data is read, the stored fabric thickness data is sequentially shifted. That is, the latest fabric thickness data is in P _0, fabric thickness data was last P ₀ is in P _1, fabric thickness data was last P ₁ is the P _2, such an operation is given needle It takes a few minutes.

In parallel with these operations, the feed pitch F from the feed set value sensor 29 is read (step 4).
From the distance x between the needle drop B and the cloth thickness detection position and the feed pitch F, the number of stitches N from the needle drop B to the cloth thickness detection position is obtained from the following equation (step 5). N = x / F

Then, the cloth thickness data P _N before N stitches is read from the cloth thickness stack (step 6). This cloth thickness P _N is the cloth thickness at the current needle drop B. That is, at the cloth thickness detection position before the needle drop B, the cloth position detected before is now at the needle drop B position by sewing the N needle, and this cloth thickness is at the needle drop point B. Cloth thickness.

The cloth thickness data P _N is not the cloth thickness detected by the displacement of the presser foot 5 but the cloth thickness detected at the cloth thickness detection position before the needle drop B, and the cloth thickness before and after the stepped portion. Even though the cloth thickness is not affected by the step portion, it is not the cloth thickness detected at the cloth thickness detection position at the present time but the actual cloth thickness detected at the cloth thickness detection position several stitches earlier, Highly accurate cloth thickness data is obtained regardless of the presence or absence of a step.

However, in the step portion, FIG.
As shown in (a), in the case of a particularly hard cloth, the slope 6
9, the actual cloth thickness of the inclined portion 69 is the thickness T of one sheet. However, since the cloth thickness detecting device G actually detects the cloth height, FIG. As shown in b), a value larger than the actual cloth thickness T is detected.

Therefore, in the present embodiment, the inclined portion 6
The following method is adopted to make the cloth thickness at 9 high precision. That is, the cloth thickness data P _N-1 of _one stitch of _N is read from the cloth thickness stack (step 7), and the read cloth thickness data P _N and P _N-1 are compared by the following comparison formula. Thus, the inclination of the work cloth is determined (step 8). P _N −P _N−1 > d where d is a cloth thickness difference detection constant (for example, 0.4 mm).

Here, if P _N -P _{N -1} <d, it is determined that the needle entry B does not have the inclined portion 69, and the high-accuracy cloth thickness data P _N and the data read in step 4 are read. The feed pitch F is substituted into each of the above-described arithmetic expressions to determine the thread feeding amounts Q1, Q2, and Q3, respectively (steps 9, 9).
11) Return to step 1.

On the other hand, if P _N -P _N-1 > d, it is determined that the needle entry B has the inclined portion 69, and the latest cloth thickness data P ₀ is used instead of the cloth thickness data P _N ( Step 10).
Thereby, as shown in FIG. 10C, the cloth thickness data becomes ideal with the error in the inclined portion 69 eliminated.

Then, the latest cloth thickness data P ₀ and the feed pitch F read in step 4 are read.
Are substituted into the above-described arithmetic expressions, and the thread payout amounts Q1, Q
2 and Q3 are obtained (step 11), and step 1
Return to

When the CPU 80 detects the rising edge a1 (20 °) of SYNC1, the CPU 80 drives the stepping motor 36a at this timing.
The needle thread 15 is paid out by the thread payout amount of the needle thread 15 calculated by calculation. In practice, the rotation angle of the stepping motor 36a capable of feeding out the yarn feeding amount is determined based on the diameter of the feeding roller 37 and the yarn feeding amount,
The stepping motor 36a is driven by the number of steps corresponding to the rotation angle.

Subsequently, when the CPU 80 detects the falling edge a2 (160 °) of SYNC1, the CPU 80 drives the stepping motor 36b at this timing, and the upper looper thread 17 of the upper looper thread 17 obtained by calculation is calculated. The thread is fed in the same manner as the needle thread 15 with the thread payout amount.

Subsequently, when the CPU 80 detects the falling edge a4 (210 °) of SYNC2, it drives the stepping motor 36c at this timing to replace the lower looper thread 18 with the lower looper thread 18 obtained by calculation. The thread is fed in the same manner as the needle thread 15 with the thread payout amount. Further, at the same time as this timing, the CPU 80 starts the operation after step 2 in FIG. 8 described above, and obtains the next thread payout amounts Q1, Q2, and Q3, respectively. By repeating the above operation, overlock stitches are formed at the ends of the cut and aligned work cloth.

In this embodiment, the needle thread payout phase is set to 20 ° and the upper looper thread payout phase is set to 160 °.
The reason why the lower looper yarn feeding phase is set to 210 ° will be described. FIG. 12 is a characteristic diagram showing a relationship between a tension change and a phase of each thread when the sewing machine according to the present embodiment is changed to a disc tension type thread tensioner and an overlock sewing is performed.

The valleys in the figure indicate that the tension is higher, and the above-mentioned feeding phase is performed after the tension of each yarn becomes maximum. In other words, by feeding each thread at these feeding phases, the fed thread is reliably consumed at the stitch.

As described above, in the present embodiment, the cloth thickness at the cloth thickness detection position before the needle drop B is detected and the memory 9 is detected.
4 and the cloth thickness data at the needle drop B is specified from the cloth thickness data stored in the memory 94 based on the distance x between the cloth thickness detection position and the needle drop B and the cloth feed amount F. Based on the thickness data, the thread payout amount necessary for the stitch is fed out by the thread payout devices 36a to 36c for each stitch, so that the cloth thickness at the needle drop B that determines the thread payout amount is:
This is not the cloth thickness detected at the current cloth thickness detection position but the actual cloth thickness detected at the cloth thickness detection position several needles earlier, and the cloth thickness detected by the displacement of the presser foot 5. Instead, the cloth thickness is detected at the cloth thickness detection position before the needle drop B, and the cloth thickness before and after the step is not affected by the step, so that only the necessary yarn amount is fed regardless of the step. You can do it.

Further, the inclination of the cloth is determined based on the cloth thickness data stored in the memory 94, and if the cloth is inclined, the cloth thickness data at the needle drop B is converted to only the cloth thickness at the inclined section 69. Since the corresponding cloth thickness data is changed and the thread payout amount required for the stitch is fed by the thread payout devices 36a to 36c for each stitch based on the changed cloth thickness data, the cloth inclined portion 69 is used. In this case, only the cloth thickness, not the cloth height, becomes the cloth thickness at the needle drop B, so that a beautiful seam can be formed even on the cloth inclined portion 69.

Next, the yarn breakage detecting mechanisms 52 and 53 described above
Will be described. During sewing, the looper balance 14 swings in conjunction with the main shaft 13, and the looper threads 17, 18 fed out by the stepping motors 36b, 36c are consumed at the stitches. Here, when the looper balance 14 is located near the position shown by the dotted line in FIG. 1, the tension of each of the looper yarns 17 and 18 increases, and each of the yarn breakage sensors 55 of the yarn breakage detection mechanisms 52 and 53 becomes It is shielded by the shield plate 58b (hereinafter referred to as closed, and the case not shielded is referred to as open). Normally, when regular sewing is performed, a change from open to closed or open occurs once during one revolution of the main shaft 13.

If a thread break occurs for any reason, the tension of the broken thread does not increase even when the looper balance 14 swings, so that the thread break sensor 55 remains open. Therefore, the CPU 80 determines that 1
If the signal of the turn-close is not input, it is determined that the thread break has occurred, and the stepping motor corresponding to the thread break sensor having no close input is stopped.

As described above, when a yarn break occurs, the stepping motor that feeds the yarn is stopped, so that the yarn is entangled with the yarn feed roller due to slack in the yarn path that occurs when the yarn is unwound. And the like can be prevented.

Since the thread breakage detecting mechanisms 52 and 53 are arranged at locations where the tension of the yarn greatly changes in the yarn path, even when the looper yarns 17 and 18 which are easily stretched are used, for example, the yarn breakage is detected. It can detect with high accuracy.

Next, the operation for setting or removing the work cloth, replacing the presser foot 5, etc. will be described below with reference to FIGS. When the operator rotates the presser lifting lever 64 in a predetermined direction (clockwise in FIG. 3), the cam portion 64a of the presser lifting lever 64 comes into contact with the projection 20b of the cloth thickness base 20, and the cloth thickness base 20 , Rises against the urging force of the cloth thickness base spring 63. Then, cloth thickness stand 2
No. 0 projection 20b abuts on the projection 50b of the presser bar holder 50, and together with the presser bar holder 50b, the presser bar 6
As a result, the presser foot 5 also rises.

As the cloth thickness table 20 rises, the potentiometer plate 21, the cloth thickness link 23, the cloth contactor 22 and the like also rise, and the potentiometer plate 21
0 abuts on the stopper 71. In this state, since the cloth thickness table 20 further rises, the potentiometer 21 rotates counterclockwise about the shaft 65 as a fulcrum against the urging force of the tension spring 67. Thereby, the cloth thickness link 23
Rise, the cloth contact 22 pivots upward with the shaft 66 as a fulcrum, and the cloth contact portion 22a separates upward from the presser foot 5.

As described above, in the present embodiment, the cloth contactor (detection lever) 22 is pivotally supported on the cloth thickness table (support member) 20 which is independent of the rise and fall of the presser bar 6. Therefore, at the time of sewing, the cloth thickness can be accurately detected in relation to the swing of the cloth contact 22 without being affected by the displacement of the presser bar 6, and the cloth thickness supporting the cloth contact 22 can be detected. Since the base 20 is interlocked with the operation of the presser foot, when the presser foot is lifted, the cloth thickness table 20 is also raised, and the cloth thickness table 20 is not obstructed, and the setting and taking out of the cloth and the presser foot 5 are performed. Can be exchanged.

Further, the cloth contact 22 is connected to the tension spring 67.
As described in Japanese Patent Publication No. 2-40354, when an excessive force acts on the cloth contact portion 22a at the tip of the cloth contactor 22 from below, it is detected. As compared with the case where the lever is urged against the cloth surface by a torsion coil spring, the force acting on the cloth contact 22 can be released better, and the cloth contact 22 can be prevented from being bent or damaged. Has become.

FIG. 13 is a perspective view showing another embodiment of the cloth thickness detecting device, and FIG. 14 is a left side view thereof. In this embodiment, the above-described potentiometer (cloth thickness sensor) 24 is attached to the thickness base 20 via an attachment plate 72. An arm 73 is fixed to the rotation shaft 24a of the potentiometer 24.
The cloth contact 22 is pressed downward by the urging force of a tension spring 74 having one end locked to the arm 73 and the other end locked to the cloth thickness base 20.

Therefore, when the cloth contact 22 swings about the shaft 66 as a fulcrum according to the thickness of the cloth, the arm 73 follows the swing.
At the same time, the rotation shaft 24a of the potentiometer 24 is rotated, so that the potentiometer 24 moves the work cloth at the position where the cloth contact portion 22 contacts the work cloth (cloth thickness detection position), as in the previous embodiment. Output a voltage corresponding to the thickness of the cloth.

It is needless to say that the same effect as that of the above embodiment can be obtained even with this configuration, and in addition, the potentiometer 24 is directly fixed to the cloth thickness base 20. Therefore, the number of parts can be reduced, cost can be reduced, and inertia damping and the like can be reduced, so that reliability can be improved.

Although the invention made by the inventor has been specifically described based on the embodiment, the present invention is not limited to the above embodiment, and various modifications can be made without departing from the gist of the invention. Needless to say, for example, in the above embodiment, the tension springs 67 and 74 are used as the springs for urging the cloth contactor 22 downward.
It is also possible to substitute a compression spring by slightly changing the configuration.

In the above embodiment, the cloth thickness sensor 24 is a potentiometer, but may be replaced with, for example, a Hall element, a magnetic sensor, a CCD linear sensor, a PSD displacement sensor, or the like.

In the above-described embodiment, the operation value is obtained by performing various operations. However, the operation value may be obtained from a data table.

The present invention can be applied not only to the overlock sewing machine described above, but also to other sewing machines, for example, to a lockstitch sewing machine and the like.

[0081]

As described above, in the sewing machine cloth thickness detecting device according to the first aspect, the detection lever is pivotally supported by the support member independent of the rise and fall of the presser bar. Since it is configured to detect the cloth thickness in relation to the swing of the detection lever without being affected by the displacement of the rod, it is possible to perform accurate cloth thickness detection that is not affected by the displacement of the presser bar. In addition, the supporting member supporting the detection lever is lifted in conjunction with the lifting operation so that the supporting member is raised, so that the supporting member does not interfere with the setting and removal of the cloth, and the presser foot. Since it is configured to be able to perform exchange and the like, it is possible to improve the operability of these.

The cloth thickness detecting device for a sewing machine according to the second aspect of the present invention, in addition to the first aspect, urges the detection lever against the cloth surface by a compression or tension spring, and applies an excessive force to the tip of the detection lever from below. When acted on, Japanese Patent Publication No. 2-40354
As described in Japanese Patent Application Laid-Open Publication No. H11-115, compared to the method in which the detection lever is urged against the cloth surface by a torsion coil spring, the force acting on the detection lever can be satisfactorily released. It is possible to prevent the detection lever from being bent or damaged.

[Brief description of the drawings]

FIG. 1 is a front configuration diagram illustrating an overlock sewing machine to which the present invention is applied.

FIG. 2 is a perspective view showing a cloth thickness detecting device of the sewing machine.

FIG. 3 is a left side view showing the cloth thickness detecting device.

FIG. 4 is a plan view showing a needle plate of the sewing machine.

FIG. 5 is a plan sectional view showing a thread breakage detection mechanism of the sewing machine.

FIG. 6 is an exploded perspective view showing the same thread breakage detection mechanism.

FIG. 7 is a block diagram showing a control system of the sewing machine.

FIG. 8 is a flowchart showing a cloth thickness detecting operation procedure and a thread payout amount acquiring operation procedure of the sewing machine.

FIG. 9 is an explanatory diagram showing one operation procedure of the above cloth thickness detection operation procedure.

10A and 10B show a cloth step portion, wherein FIG. 10A is a cross-sectional view, FIG. 10B is a cloth thickness data detected by a cloth thickness detection device, and FIG. 10C is a diagram showing an actual cloth thickness. It is.

FIG. 11 is a timing chart showing a calculation time for calculating a payout amount of each yarn and a payout time.

FIG. 12 is a diagram illustrating a change in tension of each thread with respect to a phase in a case where a one-needle three-thread overlock stitch is performed and a thread tensioner of a plate pressure type is used.

FIG. 13 is a perspective view showing another embodiment of the cloth thickness detecting device.

FIG. 14 is a left side view showing another embodiment of the cloth thickness detecting device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 5 Presser foot 6 Presser bar 9 Needle plate 20 Support member 22 Detection lever 22a Tip of detection lever 66 Support shaft 67, 74 Tension spring T Cloth thickness

 ──────────────────────────────────────────────────の Continuing from the front page (72) Inventor Yutaka Asaba 1 Juki Co., Ltd. 8-2-2 Kokuryo-cho, Chofu-shi, Tokyo

Claims (2)

[Claims] 1. A detection lever having a tip contacting a surface of a cloth on a needle plate and swinging about one axis according to the thickness of the cloth,
In a sewing machine cloth thickness detecting device capable of detecting a cloth thickness in association with the swing of the detection lever, the detection lever is moved up and down in conjunction with a press-up operation, and the presser bar is raised due to a change in the cloth thickness. A sewing machine cloth thickness detecting device, which is supported on an independent support member against a downward change. 2. A cloth thickness detecting device for a sewing machine according to claim 1, wherein the detecting lever is urged to the cloth surface by a tension or compression spring.