JPH02142595A - Feed releasing sewing machine - Google Patents

Abstract

PURPOSE:To enable a cloth to be inserted and drawn out from between a cloth holder and a needle plate without providing a large device by reversing controllably a drive shaft until a feed tooth is located below the upper surface of the needle plate according to the detection of a detecting signal in a releasing phase where a needle thread is released from a needle thread catching means according to the generation of a stop signal. CONSTITUTION:A holding rod 48 is set to a releasing position by operating a holding lever 59 to insert a cloth between a holder 20 and a needle plate 18, and a holding lever position detecting means 51 outputs a holding lever position detecting signal according to the ascent of a holding rod embracing body 49. A phase detected by a drive shaft rotational phase detecting means 79 according to the detecting signal is judged whether or not it is above a needle in a phase after a needle thread is released from a needle thread catching means. If it is the upper dead point phase of the needle, a sewing machine motor 57 is reversed so that the phase is controlled to a phase in which the needle is above and the upper end of a feed tooth is sunk from the needle plate 18 without any troubles in the insertion of the needle. Also, similar control is performed in the withdrawal of cloth after the completion of sewing.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a sewing machine equipped with a control means for controlling a feed dog of a needle thread catching means to a position below the upper surface of the throat plate after the needle thread is released.

(Prior art and problem to be solved by the invention) Generally, when attaching or detaching workpiece cloth to a sewing machine, the presser foot is raised to the upper release position by operating the presser foot lifter when the needle is at the upper stop position. be exposed.

The control phase in an electronic sewing machine for controlling the stop position of the needle is determined based on the motion curves of each part of the sewing machine as shown in FIG. The horizontal axis in the figure represents the rotation angle of the drive shaft with the top dead center phase of the needle as zero degrees. The vertical axis represents the amount of displacement,
Zero on the vertical axis indicates the top position of the throat plate.

A is the movement curve of the tip of the needle, AO is the needle top dead center, Al
is the needle bottom dead center. B is the vertical movement curve of the upper end of the feed dog, Bl is the feed dog rising start position where the upper end of the feed dog rises and coincides with the upper surface of the throat plate, and B2 represents the position where the upper end of the feed dog descends and coincides with the upper surface of the throat plate. ; Feed dog lowering start position. C is the needle thread supply amount curve by the thread take-up, and D is the hook needle thread required amount curve.

As is clear from the hook needle thread requirement curve, the bottom dead center A of the needle
The phase in which the needle thread is captured by the needle thread capturing means when rising from I is DI, and the phase in which the needle thread is released is B2, which is the phase immediately before the counted dead center phase AO.

Conventionally, the upper stop position for attaching and detaching the workpiece cloth is after the dead center of the needle thread because it must be after the release phase B2 of the needle thread by the needle thread catching means in order to pull out the needle thread.

As is clear from the figure, in this release phase D2, the feed dog is at a substantially raised feed position above the throat plate, so the amount of rise of the presser foot raised by lifting the presser foot is reduced by the amount of rise of the feed dog. Become. For this reason, when inserting extremely thick cloth, it interferes with the feed dog and the actual pressing force is reduced.

For this reason, Japanese Patent Publication No. 63-46711 proposes a feed dog lowering device that lowers the feed dog from the upper surface of the throat plate to a position lower than the conventional darning position in conjunction with the presser foot lifting operation.

However, implementing this proposal requires a large-scale device including a presser foot lifter, a feed dog lowering device, a feed dog return device, and a means for connecting these devices.

Therefore, in the present invention, by adding a simple device to the conventional sewing machine, it is possible to insert the cloth when the needle is raised.
It is an object of the present invention to provide a device for controlling a feed dog to a position where it does not interfere with workpiece cloth during take-out.

(Means for Solving the Problems) Therefore, in the present invention, a needle connected to a drive shaft connected to a drive source moves up and down, a needle thread catching means that cooperates with the corrosive needle, and a needle thread catching means that synchronizes with the up and down movement of the needle. a stitch forming means consisting of a thread take-up driven by the needle; a feed dog that moves up and down in synchronization with the up and down movement of the needle and moves back and forth to feed the cloth in cooperation with the presser foot; A detection means for detecting a rotational phase of the drive shaft detects a rotational phase, and a detection signal of a release phase in which the needle thread is released from the needle thread catching means in response to generation of a stop signal causes the drive shaft to be controlled by the feed dog. and a control means for controlling the reverse rotation until the plate is located below the top surface of the plate.

The reverse rotation control is performed by detecting means for detecting a release operation of the presser foot to set the presser foot to the upper release position when the needle stops in the upper position after the needle thread is released from the needle thread catching means. It is also possible to configure a control means that controls the reverse rotation based on the detection signal.

(Example) Next, an example of the present invention will be described in detail with reference to the drawings.

FIG. 2 is an external view of the sewing machine of the present invention, and the explanation will be made in addition to the mechanism explanatory diagram of FIG. 3. In FIG. 2, reference numeral 4 denotes a pattern selection means, on which a pattern display and a pattern number are displayed, and a desired pattern is selected by operating number keys 5 from 0 to 9. This selected number is displayed on the pattern display means 6. Note that the pattern display may be one in which the pattern itself is displayed using an LCD or the like.

A drive shaft 2 connected to a drive source (not shown) to transmit rotation is rotatably supported in the sewing machine frame 1, and a needle bar 3 connected to the drive shaft is connected to the sewing machine frame 1. It is supported so that it can move up and down. A needle 17 is fixed to the tip of the needle bar 3.

In FIG. 3, a needle bar crank 8 is fixed to one end of a crank 7 provided at the shaft end of the drive shaft 2, and one end of a crank rod 9 is rotatably fitted onto the shaft of the needle bar crank. ing.

The other end of the crank rod is rotatably fitted to the shaft of a needle bar holder 10 through which the needle bar 3 is inserted, and the needle bar 3 is attached to a needle bar support above and below the needle bar holder 10. 11 so that it can move up and down.

The needle bar support body is fitted onto a shaft 12 fixed to the sewing machine frame 1, and is supported so as to be movable only in the rotational direction, with vertical movement restricted.

One end of a connecting rod 13 is connected to the opposite side of the needle bar support 11 from the needle bar 3, and the other end of the connecting rod is connected to the needle bar amplitude stepping motor 14 fixed to the sewing machine frame l. It is connected to the output shaft 14a via a fixed arm 15 and a link 16.

A needle plate 18 is fixed to the sewing machine frame 1 below the needle bar 3. The needle plate 18 has a needle hole 18a through which a needle 17 fixed to the tip of the needle bar 3 is inserted.

Reference numeral 19 denotes a feed dog which protrudes and retracts from a feed dog groove 18b provided in the throat plate 18 and cooperates with the cloth presser foot 20 to move the cloth held therebetween in synchronization with the vertical movement of the needle 17.

The feed dog 19 is fixed to a feed table 21 connected to a horizontal feed shaft 32 driven by the drive 1111b2, and the amount of movement of the feed table 21 is adjusted by adjusting the amount of swing of the feed shaft 32. .

Reference numeral 22 denotes a feed adjuster, which is fixed to the shaft end of a feed adjustment shaft 23 that is rotatably supported on the sewing machine frame 1. By rotating the feed adjustment shaft, the feed adjuster 22 can be adjusted. Adjust the feed amount by changing the angle.

That is, the amount of transmission of the momentum of the longitudinal feed movement generated by the horizontal feed cam 45, which is an eccentric cam fixed to the lower shaft 29 connected to the drive shaft 2 and rotatably supported by the sewing machine frame 1, is adjusted. It is something.

An arm 24 is fixed to the other end of the feed adjustment shaft 23, and a link 27 is formed between the arm 24 and an arm 26 fixed to the output shaft of a feed adjustment stepping motor 25 fixed to the sewing machine frame l.
are connected via.

Reference numeral 28 denotes a hook which is a needle thread supplementing means, and is rotatably supported by the sewing machine frame 1 below the needle plate 18, and connected to the drive shaft 2 so as to synchronize with the vertical movement of the needle 17. A gear 30 fixed to the rotating lower shaft 29 and a hook gear 31 fixed integrally to the lower part of the hook 28 mesh with each other to transmit rotation.

Reference numeral 79 denotes drive shaft phase detection means, which includes a rotary plate 80 fixed to the drive shaft 2 and the sewing machine frame 1, as shown in FIG.
The photointerrupter 81 is fixed to the photointerrupter 81.

Since the phase detection by the drive shaft phase detection means 79 is the same as that of Japanese Patent Application Laid-open No. 55-73288 previously filed by the present applicant, a description thereof will be omitted.

Reference numeral 63 denotes a known balance, which is connected to the crank 7 and is configured to move up and down in synchronization with the up and down movement of the needle.

The feeding mechanism of the feeding dog 19 will be explained.

The horizontal feed shaft 32 is rotatably supported by a pair of tapered screws 33 and 34 screwed into the sewing machine frame 1, and arm portions 32a and 32b are formed at both ends of the horizontal feed shaft.

A bottle 39.40 is fixed to the tip of the arm by a screw 37.38 parallel to the horizontal feed shaft 32.

The feed base 21 is fitted into the bin 39.40 so as to be rotatable and movable in the axial direction of the bin 39.40. The lower part 21a of the feed table 21 is disposed on a vertical feed cam 41, which is an eccentric cam fixed to the lower shaft 29, and is always in contact with and driven by the vertical feed cam by a spring means (not shown). It is made to move up and down.

A pin 43 is fixed to the intermediate portion between the center of swing of the horizontal feed shaft 32 and the tip of the arm, and one end of a feed prong 44 is rotatably fitted into the pin.

The two prongs of the two feed prongs are fitted onto the outer periphery of a feed cam 45, which is an eccentric cam fixed to the lower shaft 29, and a pin 46 is fixed to one of the two prongs. A square separator 47 is fitted into the bin, and the square separator is connected to the feed adjuster 2.
It fits into the adjustment groove 22a of No. 2.

The two feed prongs 44 move the horizontal feed shaft 32 to the pair of tapered screws 33 and 34 according to the inclination of the feed adjuster 22.
The feed table 21 is moved back and forth by swinging around the center.

Next, a device for detecting the upper release position of the presser foot lifter will be explained with reference to FIG.

Reference numeral 48 denotes a presser bar, which is supported by the sewing machine frame l so as to be movable up and down, and has the presser foot 20 attached to its tip.

Reference numeral 49 denotes a presser bar holder, which is fitted and fixed to the presser bar, and is normally pressed forward via the presser bar holder 49 by the bias of a presser spring 50 disposed between the sewing machine frame 1 and the sewing machine frame 1. A clamping force is generated between the presser foot 20 and the feed dog 19 by pressing the presser bar 48 downward.

Reference numeral 59 denotes a presser foot lifter, which is rotatably fitted into the stepped portion of a stepped screw 60 fixed to the sewing machine frame l, and when operated, comes into contact with the presser bar holder 49 and biases the presser spring 50. It is configured such that it rises against the pressure and is set at the release position.

Reference numeral 51 denotes a microswitch as presser foot lifting position detecting means, which is fixed to the sewing machine frame l, and the tip of the detector is disposed on the upper surface of the presser foot holder 49.

The presser foot lifting position detecting means 51 is configured such that when the presser foot bar holder 49 is set to the upper release position, the upper surface of the presser foot rod holder comes into contact with the detector and outputs a detection signal of a presser foot lifting operation.

Next, the control device will be explained with reference to FIG.

The pattern selection means 4 and the presser foot lifting position detection means 51
, the drive shaft rotation phase detection means 79 and the pattern display means 6 are connected to the central processing unit 52.

Reference numeral 53 denotes selected pattern storage means, and the pattern selection means 4
It is connected to the central processing unit 52 and stores the pattern selected by the user.

Design data storage means 54 is connected to the central processing unit 52 and stores stitch data of patterns selectable by the pattern selection means 4 and pattern display data.

Reference numeral 55 denotes a control data storage means, which stores release phase data, counted dead center phase data, and reverse rotation stop phase data of the needle thread catching means 28, and is connected to the central processing unit 52.

The needle bar amplitude stepping motor 14 and the feed adjustment stepping motor 25 are connected to the central processing unit 52 via a stepping motor drive circuit 56.

Reference numeral 57 is a sewing machine motor which is a driving source, and in this embodiment, a C servo motor is used because fine control is easy.
The motor is connected to the central processing unit 52 via a motor drive circuit 58.

Next, the operation of the sewing machine of the present invention will be explained with reference to the flowchart shown in FIG.

A desired pattern is selected by operating the numerical keys 5 of the pattern selection means 4. In order to insert the cloth, it is determined in step (a) whether or not the drive shaft 2 is stopped.

If the sewing machine motor 57 is not stopped but is rotating, the sewing machine motor 57 is stopped in step (b).

Next, in step (c), it is determined whether or not the presser foot lifter has been operated.

In order to insert the cloth between the presser foot 20 and the throat plate 18, the presser foot lifter 59 is operated to rise against the bias of the presser spring 50, and the presser foot bar 48 is set to the release position. .

As the presser bar holder 49 fixed to the presser foot bar rises, the presser foot lifting position detecting means 51 outputs a presser foot lifting position detection signal.

In response to the detection signal, in the next step (d), the stop position may be determined by the phase detected by the drive shaft rotation phase detection means 79 by the needle thread catching means 28 or the needle thread at the phase after the needle thread is released. It is determined whether or not it is in the upper position.

If the sewing machine motor 57 is not in the phase before release and in the needle upper position, the sewing machine motor 57 is driven in step (e) to the needle upper position after release, and in the case other than AO in FIG. 8, the sewing machine motor 57 is driven to the counted dead center phase.

If it is the counted dead center phase, in step (f), the sewing machine motor 57 is rotated in the opposite direction to the direction of rotation for stitch formation, so that the needle 17 is in the upper position and the feed dog 19 is in the upper position. Control is performed to a phase in which the upper end is recessed from the throat plate 18, which is a phase before B1 in FIG.

The raised position of the presser foot 20 when the presser foot is lifted is the raised position in which the needle 17 is lowered. Generally speaking, it is set to about 10 millimeters at maximum.

In the control phase, the tip of the needle 17 is approximately 14 mm above the throat plate I8 (position A3), and the tip of the needle 17
The position is well above the bottom edge of the .

At the same time, the feed dog] 9 is recessed from the throat plate 18,
There is no problem in inserting cloth.

Furthermore, since the same control is executed for taking out the cloth after sewing is completed, the feed dog 1
A state is set that is not affected by the tip of 9.

Incidentally, in this embodiment, the control phase is a phase in which the feed dog 19 is sunk downward from the throat plate 18, but the feed dog 19 remains on the upper surface of the throat plate 18 to the extent that it does not affect the drawing of the cloth. It's okay to have one.

In this embodiment, when the sewing machine is stopped after the needle thread is released from the needle thread catching means 28, the drive shaft 2 is controlled to rotate in the reverse direction by operating the presser foot lifter 59. Regardless of the operation, when a stop signal is generated during rotation, the stop phase of the drive shaft 2 is always set so that the feed dog 19 is recessed from the upper surface of the throat plate 18 after the needle upper force reaches the position after the needle thread is released. It is also possible to use a device that rotates in the opposite direction up to the phase that is reached.

In addition, when the feed dog 19 is recessed from the upper surface of the throat plate 18, the presser foot lifter 59 is operated to release the thread tension device 61 (see Fig. 7) to loosen and take out the needle thread, and to remove it from the needle after it has not been cut. When a cloth is inserted and the presser foot lifter 59 is operated to hold the cloth under the cloth presser foot 20, the thread tension device 61 returns to hold the needle thread.

At this time, the balance 63 is in the lower position. In order to prevent the needle thread on the cutting side from coming out of the needle due to the rise of the thread take-up when the sewing machine is started, as shown in FIG. A thread unwinding lever 62 that releases the thread tension device 61 in conjunction with the thread tension lever 62 is integrally formed with a thread unwinding lever part 62a to prevent the thread from coming off by pulling out the needle thread in advance when loosening the thread.

Further, instead of the thread pay-out lever part 62a, a known needle thread supply device for supplying needle thread may be placed between the thread take-up lever 63 and the needle thread supply source and operated.

(Effects of the Invention) As described above, according to the present invention, the drive shaft is reversed after reaching the needle thread release phase required for cloth withdrawal (7).
Since Janome Sewing Machine Industry Co., Ltd. has the upper end of the feed dog in a lowered position that does not interfere with the attachment and removal of cloth, a large-scale device must be installed to insert and remove cloth between the presser foot and throat plate. It can be done without.

[Brief explanation of the drawing]

The drawings relate to embodiments of the present invention, and FIG. 1 shows a control block, FIG. 2 shows an external view of the sewing machine, FIG. 3 shows an explanation of the mechanism of the sewing machine, FIG. 5 is a flowchart explaining the operation, FIG. 6 is an explanation of the drive shaft phase detection means, FIG. 7 is an explanation of the thread pay-out lever, FIG. 8 is an explanation of the motion curves of each part of the sewing machine, and 57 Sewing machine motor as a driving source; 2 is a drive shaft; 17 is a needle; 28 is a hook as needle thread catching means; 20 is a presser foot; equipment and 5
The motor drive circuit 7 is a control means. Figure Figure Figure Figure

Claims (2)

[Claims] (1) Stitch forming means consisting of a needle that is connected to a drive shaft that is connected to a drive source and moves up and down, a needle thread catcher that cooperates with the needle, and a thread take-up that is driven in synchronization with the up and down movement of the needle. a feed dog that moves up and down in synchronization with the up and down movement of the needle and moves back and forth to feed the cloth in cooperation with the presser foot; and a drive shaft rotational phase detection means that detects the rotational phase of the drive shaft. , upon detection of a detection signal of a release phase in which the needle thread is released from the needle thread catching means in response to generation of a stop signal, the drive shaft is controlled to rotate in reverse until the feed dog is located below the upper surface of the throat plate. A feed release sewing machine consisting of a control means. (2) Stitch forming means consisting of a needle that is connected to a drive shaft connected to a drive source and moves up and down, a needle thread catching means that cooperates with the needle, and a thread take-up that is driven in synchronization with the up and down movement of the needle. a feed dog that moves up and down in synchronization with the up and down movement of the needle and moves back and forth to feed the cloth in cooperation with the presser foot; a presser foot lifter for setting the presser foot in an upper release position; presser foot lifting position detection means for detecting the release position of the presser foot; drive shaft rotational phase detection means for detecting the rotational phase of the drive shaft; and a drive shaft rotational phase detection means for detecting the rotational phase of the drive shaft; control means for controlling the drive shaft to reversely rotate in response to a detection signal of the presser foot release position from the presser foot lifting position detecting means when the drive shaft is stopped until the feed dog is located below the upper surface of the throat plate; A free-feed sewing machine.