JPH08206384A - Device for informing user that the under thread of a sewing machine is going to run out - Google Patents

Abstract

PURPOSE: To previously inform that the under thread is going to run out by providing a marked conductive matter near the end of under thread, and detecting it with a current application sensor. CONSTITUTION: When winding under thread 22 on a bobbin, a marking of conductive material is provided at the place about 1.5m from the commencement of winding. This bobbin is charged in a bobbin case 23, and sewing is made. When the under thread 22 is consumed, and the marked section of the conductive material becomes tangled with the upper thread 21 and makes perforations and it contacts with the sensor terminal 9 of a needle plate 1, a current application sensor (composed of a current application sensor body 29 and the sensor terminal part 8), and issues an alarm. By doing like this, a worker presses a reset push button switch 26, and interrupts the sewing in proper work process before the under thread 22 runs out, and replaces the under thread. This way, the continuation of the wasteful sewing work can be prevented, and the loss of work time can be prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for indicating when a bobbin thread of a lockstitch sewing machine equipped with an energization sensor is running out.

[0002]

2. Description of the Related Art In a conventional lockstitch sewing machine, there is no practical device for indicating that the bobbin thread is about to run out, and there is no device for notifying that the bobbin thread is about to run out.

[0003]

Since the lockstitch sewing machine creates perforations of the upper thread on the cloth in the same state as when only the upper thread is properly sewn with the lower thread, there is no need for the lower thread. Does not notice that the bobbin thread has run out and continues the wasteful sewing work. In addition, some materials have needle holes and cannot be re-sewn, resulting in many economic losses.
The present invention solves these problems, and catches the conductive material marked near the end of the lower thread with an energization sensor to notify in advance that the lower thread is running out.

[0004]

[Means for Solving the Problems] As means for solving the problems, a needle plate (1), a feed dog (11), and a presser foot (1
4), an energization sensor (sensor terminal portion (8), energization sensor body (29)), a conductive substance for marking the lower thread, etc. are required.

The needle plate (1) catches the conductive material marked on the lower thread, and is a wiring hole for passing a terminal connecting wire 5 mm above the edge 30 ° above the needle plate in order to incorporate the energization sensor terminal portion. (2) is made, and the width is 2.5 between the needle hole (3) and the central feed dog groove (5) to the wiring hole (2).
An L-shaped wiring groove (7) having a depth of 1 mm is formed, and the center feed tooth groove (5) and the right feed tooth groove (6) are located 1 mm before the wiring groove (7).

The feed dog (11) has a central feed dog (12).
Then, the right feed dog (13) is shortened so as to match the center feed dog groove (5) and the right feed dog groove (6) of the needle plate (1) of the present invention. Further, the conventional one may be cut into short pieces to fit the feed dog groove of the present invention.

The presser foot (14) of the conventional shape is used, but a bottom surface of about 5 mm ² closer to the support post than the needle drop portion (15) is a 0.8 mm depression (16), and its surface has a thickness of 0.5 mm. The insulating film resistant to friction is applied so that the sensor terminal (9) and the metal on the bottom surface of the presser foot do not come into contact with each other and do not energize.
Further, a special presser foot such as a three-roll presser foot which is not always used can be used by applying an insulating film resistant to friction on the surface corresponding to the depression (16).

The sensor terminal portion (8) is composed of a sensor terminal (9) and a terminal connecting wire (10). The sensor terminal portion (8) is entirely sealed with an insulator (19) except for a part of the sensor terminal, and the needle plate (1).
The wiring groove (7) has the same L-shape as that of the wiring groove (7), and the wiring groove (7) is fitted to the same level as the needle plate (1).

The sensor terminal (9) is made of a material having good electrical conductivity and resistance to friction, and is arranged side by side in parallel at intervals of 0.4 mm, and the needle plate (1) is provided only 2 mm in front of the needle hole (3). )
It is 0.3 mm higher than the surface of, and only this higher part is exposed from the insulator (19). Terminal connection wire (10)
From the wiring hole (2) to
Connect to 9).

In the current sensor body (29), the conductive material marked on the lower thread is the sensor terminal (9) of the needle plate (1).
When it comes into contact with, the circuit will flow and a current will be activated to make a sound (alarm) to inform the operator. In the present invention, the circuit shown in FIG. 10 is used.

The power source for operating the energization sensor is a 6V power source (18) for illuminating the working lamp of the sewing machine, which is emitted from the sewing machine motor.
Connected to the power supply line (17).

A conductive material is marked near the end of the bobbin thread wound on the bobbin (this is the starting portion when the bobbin thread is wound on the bobbin). The point to be marked is generally about 1.5 m from the end of the lower thread, and the length to be marked may be about 1 cm.

When the bobbin thread disappears and the portion marked with the conductive material comes out of the bobbin case and touches the sensor terminal (9) of the needle plate (1), the circuit is connected and an alarm sound is produced.

[0014]

With the above construction, when this device is used, the bobbin thread is about to run out, and about 1.5 m is left, that is, the place (20) where the conductive substance is marked becomes the sensor terminal (9) of the needle plate (1). Upon contact, the energization sensor operates and an alarm sounds.

[0015]

EXAMPLE When winding a bobbin around a bobbin, 1.
Mark conductive material around 5m. When the bobbin thread is sufficiently wound, load it into the bobbin case and start sewing. When the bobbin thread is gradually consumed, the place where the conductive material is marked (20) is entangled with the upper thread to make a perforation, and when the sensor terminal of the needle plate (1) is contacted, current flows in the circuit of the energization sensor, and the energization is performed. The sensor activates and sounds an alarm. The operator pushes the reset push button switch (26) to interrupt the sewing in an appropriate working process before the lower thread is exhausted and replace the lower thread.

[0016]

The following three points can be mentioned as the effects of the invention. Prevents the wasteful work time from being lost by not realizing that the bobbin thread has run out and continuing wasteful empty stitching work. It prevents the loss of the needle thread, damages the needle hole to those that cannot be re-sewn, such as empty stitching and leather / coating materials, and prevents economical loss. In a stitch sewing machine that cannot be continuously sewn, an alarm sound immediately stops sewing in a well-separated process, and the bobbin thread is replaced early to prevent re-sewing due to insufficient bobbin thread during the process.

[Brief description of drawings]

FIG. 1 is a plan view of a needle plate.

FIG. 2 is a plan sectional view of a sensor terminal portion.

FIG. 3 is a side sectional view of a sensor terminal portion.

FIG. 4 is a vertical cross-sectional view of a needle hole of a needle plate and a tip of a sensor terminal.

FIG. 5 is a perspective view of a feed dog.

FIG. 6 is a perspective view of a presser foot.

FIG. 7 is a bottom view of the presser foot.

FIG. 8 is a cross-sectional view showing a state in which a portion of the lower thread on which a conductive material is marked contacts the sensor terminal.

FIG. 9 is a diagram showing a system of the present invention.

FIG. 10 is a comparator alarm circuit diagram in the main body of the energization sensor.

[Explanation of symbols]

1 Needle plate 2 Wiring hole 3 Needle hole 4 Left feed tooth groove 5 Central feed tooth groove 6 Right feed tooth groove 7 Wiring groove 8 Sensor terminal part 9 Sensor terminal 10 Terminal connection wire 11 Feed tooth 12 Central feed tooth 13 Right feed dog 14 Presser foot 15 Needle drop portion 16 Recess 17 Power line 18 6V power supply 19 Insulator 20 Place where conductive material is marked 21 Upper thread 22 Lower thread 23 Bobbin case 24 Motor 25 Red warning light 26 Reset push button switch 27 Power switch 28 29 Electricity sensor body 30 Needle 31 Sewing machine table 32 Upper cloth 33 Lower cloth

Claims (1)

[Claims] (A) A wiring hole (2) having a diameter of 3 mm or less is formed at a position 30 ° to the right of the needle plate (1) and 5 mm before the edge. (B) 2.5 mm in width and 1 mm in depth from between the needle hole (3) of the needle plate and the center feed dog groove (5) to the wiring hole (2)
Make an L-shaped wiring groove (7). (C) Of the three feed dog grooves on the needle plate (1), the center feed dog groove (5) and the right feed dog groove (6) should be located 1 mm before the wiring groove (7). (D) The feed dog (11) has a central feed dog (12),
The right feed dog (13) is shortened to fit the feed groove of the present invention. Further, the conventional one may be cut short so as to fit the feed dog groove of the present invention. (E) The presser foot (14) has a conventional shape,
About 5 mm ² of the bottom surface closer to the support post than the needle drop portion (15) is 0.
An 8 mm depression (16) is formed, and an insulating film having a thickness of 0.5 mm is applied to the surface thereof. Use an insulating film that is resistant to friction. (F) Special presser foot such as three winding presser foot
It is also possible to apply an insulating film resistant to friction to the surface corresponding to 6) for use. (G) The L-shaped sensor terminal portion (8) is fitted into the wiring groove (7) of the needle plate (1). The sensor terminal portion is composed of a sensor terminal (9) and a terminal connecting wire (10), and the entire sensor terminal (9) is sealed with an insulator (19) except for a part thereof. The thickness should be the same level as the upper surface of the needle plate when it is fitted into the wiring groove (7) and bonded. (H) The sensor terminals (9) are made of a material that has good electrical conductivity and is resistant to friction, and are arranged side by side in parallel at 0.4 mm intervals.
Only 2 mm in front of the needle hole (3) is exposed 0.3 mm higher than the surface of the needle plate (1) from the insulator (19). (I) The terminal connecting wire (10) is drawn out from the wiring hole (2) of the needle plate (1) and connected to the energization sensor body (29). (E) The current sensor body uses a current which flows when the conductive material marked on the lower thread comes into contact with the sensor terminal (9) and makes a sound (alarm sound) to inform the operator. (L) The power supply to activate the energization sensor is a 6V power supply (18) for illuminating the work lamp of the sewing machine that is emitted from the motor of the sewing machine, and this is the energization sensor body (29).
Connected to the power supply line (17). (O) Mark a conductive material near the end of the bobbin thread about 1.5 m (longer if necessary) and make a warning sound when the sensor terminal (9) is touched and the circuit of the current sensor is connected. A device that informs that the bobbin thread of the sewing machine configured as described above is running out.