JPH0240940Y2 - - Google Patents

Description

[Detailed description of the invention] This invention relates to a needle thread supply device in which a required length of needle thread is paid out from a bobbin spool in advance for each stitch formation by a payout body that reciprocates in synchronization with a thread take-up. The purpose is to prevent mistakes in threading the needle thread onto the body.

Examples of this invention will be described below with reference to the drawings.

Regarding the mechanical configuration, the sewing machine is not shown in detail, but it has a main shaft that rotates in conjunction with a drive source, a needle bar that fixes the sewing machine needle with needle thread T and moves up and down in conjunction with the main shaft, and a needle bar that serves as a needle thread supply source. The needle thread T between the bobbin spool and the sewing machine needle is supported, and the needle thread T is repeatedly tensioned and relaxed by being linked to the main shaft, and the timing curve shown in Fig. 3 with the needle bar top dead center set at 0 degrees ( This is a known device that includes a balance 1 that reciprocates between two positions according to a balance curve.

The holding means 2 and 3 are electromagnets that are arranged relatively apart from each other in the front and the front in the needle thread supply direction from the thread take-up to the thread take-up 1 on the needle thread path between the thread take-up 1 and the needle thread take-up and are connected to each other. (SOL.1) 4 and electromagnet (SOL.2) 5, and a pair of holding plates 2 which are joined by excitation and separated by de-excitation.
a, 2b and 3a, 3b, and when these holding plates are joined, the needle thread T is held immovably, and when they are separated, the needle thread T is movably released.

The guide plates 6, 7 are spaced apart from each other on both sides of the needle thread path between the two holding means 2, 3, and are fixedly arranged vertically.
Openings 6a and 7a are formed in the middle, respectively. A long groove 8a is formed in the upper part 8 of the sewing machine frame so as to face the gap between the guide plates 6 and 7.

The feeding body 9 includes a rocking body 11 whose middle portion is rotatably supported on a shaft 10 fixed to the machine frame, and a rocking body 11.
A protrusion made of a rubber material is supported in the upper part so as to be rotatable about an axis 12 parallel to the axis 10, and is always fixed to the oscillator 11 by a coil spring 13 stretched between the oscillator 11 and the oscillator 11. The openings 6 of both guide bodies 6 and 7 are made up of an extended arm 14 that applies an elastic force in the clockwise direction in FIG.
a, 7a. The extending arm 14 is
As shown in FIG. 4, the upper end surface 14a is sloped downward to the right to form a T-shape in the upper part, and the right corner is connected to the thread hooking part 1.
4b. Further, as shown in FIG. 3, when the needle thread T is relaxed by the thread take-up 1, the feeding body 14 bends and increases the needle thread path between the two holding means 2 and 3. During the tension period of T, the oscillator 1 is moved against the cam surface 15a of the cam body 15 that rotates in synchronization with the thread take-up so as not to bend the needle thread path.
The follower 11b provided at the lower part of the machine frame 1 is brought into pressure contact with the machine frame by the elastic force of a coil spring 16 stretched between the machine frame and the machine frame. The strength of the coil spring 13 is set to be weaker than the tension of the needle thread T when both the holding means 2 and 3 clamp the needle thread T while the needle thread path is being bent by the feeding body 9, and the coil spring 16 is Set stronger than the coil spring 13.

The base tension 17 is disposed between the bobbin winding and the holding means 2 so as to always provide a constant passage resistance to the needle thread T. The rotating body 18 is rotatable in proportion to the amount of needle thread T being fed out from the bobbin winding when the needle thread T is fed out from the bobbin winding in conjunction with the operation of the feeding body 9.
Place it between 3.

The base tension 19 as a resistance imparting device is similar to the base tension 17. Between the thread guides 20 and 21, which are installed separately on the needle thread path between the base tension 19 and the holding means 3, a coiled base is loosely fitted into the shaft of the machine frame, and the base end is A free end (thread hook part) 22a of a thread absorbing spring 22 as a thread absorbing device made of a fixed spring member is arranged. The elastic force of the thread absorption spring 22 is weaker than the sum of the resistance of the needle thread T due to the base tension 19 and the thread guide 21, and when the electromagnet is demagnetized, the elastic force of the thread absorption spring 22 is weaker than the sum of the resistance of the needle thread T caused by the holding means 3 and the thread guide 20 when the electromagnet is demagnetized. The elastic restoring force is set to be stronger than the sum of the passing resistances of T, and this elastic restoring force causes the yarn absorption spring 22 to constantly
The needle thread T crosses the path of the needle thread T when it is stretched straight between the threads 21, rotates by a certain angle clockwise in FIG. 1, and then stops.

Regarding the configuration of the electric circuit The feeding detection device 27 generates one pulse every time the rotating body 18 rotates by a certain angle. The position detecting device 28 is arranged in relation to the main shaft, and immediately after the feeding body 9 starts to swing counterclockwise after swinging clockwise in FIG. The rotation angle of the main shaft until just before the end of the relaxation period T is detected, and a position signal for the period H is generated. The counter 29 is reset by a position signal from the position detection device 28 and counts clock pulses from the feedout detection device 27. The setting device 30 consists of a digital switch that is set using a dial, and is set according to the length of needle thread T required to form one stitch (which varies depending on conditions such as the thickness of the fabric, the width of the needle, and the feed pitch). This is used to set the length of the needle thread T to be fed out, and a different digital code is generated corresponding to the set length. This digital code is related to the number of clock pulses from the payout detection device 27 which correspond to the rotation angle of the rotating body 18 which is proportional to the payout amount.

Comparison circuit 31 compares the output values of counter 29 and setting device 30, and generates an H match signal when both match. The operating circuits 32 and 33 receive the H signal and are opened to excite the electromagnets 4 and 5.
Upon receiving a low level (hereinafter referred to as L) signal, the electromagnets 4 and 5 are closed so as to be demagnetized. The flip-flop FF is reset by the position signal from the position detection device 28 to set the Q terminal output to L, and the match signal from the comparator circuit 31 changes the Q terminal output from L to H.
to be reversed.

Note that G is an OR gate circuit, and I ₁ and I ₂ are inverters.

Regarding the operation: When the sewing machine is driven, the thread take-up 1 rises to tension the needle thread T between the holding means 3 and the needle or stitch, and then descends to relax it, and this process is repeated. Further, during the above-mentioned needle thread relaxation period by the thread take-up 1, the swinging body 11 of the feeding body 9 moves forward in the clockwise direction in FIG. 1 in conjunction with the cam body 15 and returns in the counterclockwise direction.

When the rocking body 11 moves forward, the extending arm 14 also moves together due to the elastic force of the coil spring 13.
As shown in FIGS. 4 and 5b, the needle thread T is bent between the openings 6a to increase the needle thread path between the holding means 2 and 3. Note that during this period, the output of the position detection device 28 is L, so one electromagnet 4 is demagnetized and the other electromagnet 5 is energized, which causes the holding means 2 on the supply source side to release the needle thread T and unwind it. Side holding means 3
holds the needle thread T so that it cannot pass through, so the oscillator 1
1 moves forward, needle thread T of a length corresponding to the increase in the above-mentioned path is let out from the bobbin winding between the holding means 2 and 3.

When the needle thread T is paid out from the bobbin by the above action, the rotating body 18 rotates counterclockwise in FIG.
As a result, the feedout detection device 27 generates a number of clock pulses proportional to the rotation angle. These clock pulses are counted by a counter 29, and the counted value is inputted to one input section of a comparator circuit 31. When the count value of the counter 29 matches the output of the setting device 30, a matching signal of H is output from the comparison circuit 31, and the Q terminal output of the FF changes from L to H.
The electromagnet 4 is excited and the holding means 2 is reversed.
holds the needle thread T so that it cannot pass through, and the needle thread T is removed from the bobbin winder.
prevent it from being rolled out. At this time, the other holding means 3 continues to hold the needle thread T since the output of the position detection device 28 does not change. Therefore, after the needle thread T of the length set by the setting device 30 is let out from the bobbin winder, the needle thread T is held by both the holding means 2 and 3 so that it cannot pass through. 11, when the rocking body 11 moves forward thereafter, the coil spring 13 is stretched by the tension of the needle thread T between the holding means 2 and 3, and the feeding arm 14 continues to stop at that position. According to this, the follower 11b of the oscillator 11 is always connected to the coil spring 1.
The acting force of 6 ensures reliable contact with the cam surface of the cam body 15, and prevents the needle thread T from being drawn out more than necessary or causing thread breakage.

Next, a position signal is output from the position detection device 28 during the period from immediately after the oscillating body 11 starts to move backward from the state shown in FIGS. 4 and 5 b until just before the relaxation period of the needle thread T by the balance 1 ends. Although the electromagnet 5 is demagnetized via the inverter _I2 , the electromagnet 4 continues to be excited via the gate G, so the holding means 3 releases the needle thread T while the holding means 2 continues to hold the needle thread T. Therefore, the needle thread T let out between the holding means 2 and 3 is pulled out between the thread guides 20 and 21 by the demagnetization of the electromagnet 5 and the elastic return force of the thread absorption spring 22, and the needle thread T between the holding means 2 and 3 is stretched.

Further, since FF is cleared by the position signal from the position detection device 28, when the output of the position signal stops thereafter, the electromagnet 4 is demagnetized and the needle thread T is released from being held by the holding means 2, and the electromagnet 5 is The needle thread T is again clamped by the holding means 3 by energization.

Next, when the thread take-up 1 starts to rise from this state, the needle thread T between the thread guides 20 and 21 resists the action force of the thread absorbing spring 22 and reaches the base tension 1.
9 toward the thread take-up 1, the holding means 3 and the needle thread T between the stitches are tensioned, and the stitches are tightened and knotted. Thereafter, the above operation is repeated every time the balance 1 moves back and forth.

By the way, the needle thread T to the feeding arm 14 is passed from above the sewing machine frame 8 through the opening 8a to the guide plate 6,
However, even if the feed-out arm 14 moves forward to bend the needle thread T, the feed-out arm 14
Since the upper end surface 14a intersects the guide plates 6 and 7,
There is no possibility of threading mistakes with respect to the feeding arm 14. That is, when the sewing machine is stopped in the state shown in FIGS. 4 and 5 b, the guide plates 6 and 7 are removed from the opening 8a.
The needle thread T drawn in between them once rides on the upper end surface 14a of the feeding arm 14, but when the feeding arm 14 moves back to the state shown in FIG.
slides down along the slope and faces the thread hooking part 14b.

As described above, this device tilts the free end surface of the feeding body forward in the insertion direction and toward the thread hooking part, and at one position of the feeding body, the needle thread insertion path is opened, and at the other position, the insertion path is closed. Because the needle thread is set to a length that allows the needle thread to be inserted into the opposite side of the threading part of the feeding body, no matter where the feeding body is located, this prevents mistakes in threading the thread on the feeding body, and the needle thread is always This has the effect of accurately dispensing the amount of needle thread necessary for stitch formation and improving the quality of the stitches.In addition, by simply pressing the middle part of the needle thread against the free end surface of the dispensing body, the dispensing body moves at least once. During the movement, the needle thread is self-propelled by force on the free end surface and guided to a position where it engages with the thread hook, which also has the effect of simplifying the setting of the needle thread.

[Brief explanation of the drawing]

Fig. 1 is a perspective view of the needle thread supply device, Fig. 2 is a block diagram of the electric circuit, Fig. 3 is a time chart, Figs. 4 and 5 are explanations of operation, and Fig. 4a is Fig. 5a.
4b corresponds to FIG. 5b, respectively.

Claims (1)

[Claim for Utility Model Registration] Action allows the needle thread to pass through, non-action makes the needle thread impassable, and the needle thread is separated from the front and back in the direction of feeding on the needle thread path between the needle thread supply source and the thread take-up. Two holding means 2 and 3 are arranged, and the needle thread path between both holding means can be oscillated between one position and the other position in synchronization with the needle bar, and the needle thread can be oscillated below the free end surface thereof. Threading part 14 on one side of the direction
fixed guides disposed opposite to each other on both sides of the needle thread passage path, with moving paths 6a and 7a for the feeding body provided in the intersecting direction of the needle thread insertion path and the needle thread supply path; The needle thread required for stitch formation is fed out from the bobbin spool every time one stitch is formed by controlling the operation/inaction of both holding means in synchronization with the speed of the needle bar. In the needle thread supply device of the sewing machine, the free end surface of the feeding body is tilted forward in the insertion direction and toward the thread hooking part, and the needle thread insertion path is released at one position of the feeding body, and the insertion path is closed at the other position. A needle thread supply device for a sewing machine, characterized in that the needle thread supply device is set to a length that can be closed.