JPH0318917B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for reliably detecting thread breakage in a sewing machine.

[Conventional technology]

Thread breakage affects sewing efficiency in embroidery sewing machines and industrial sewing machines, so when a thread breakage occurs, it is immediately notified to the operator, and it is shown which sewing machine caused the thread breakage. . In this thread breakage detection method, a portion of the upper thread that is paid out above or below the thread take-up is hooked on a spring, and the upper thread is guided to the hook through the needle hole. When a thread breakage occurs, the tension of the needle thread is relaxed, the spring springs up, and contacts an electrode placed near the spring to notify the thread breakage.

[Problem to be solved by the invention]

Conventional thread breakage detection involves hooking the thread onto a spring placed above or below the thread take-up. For this reason, even if it is possible to detect thread breakage of the upper thread, it is impossible to detect thread breakage of the lower thread.

An object of the present invention is to make it possible to reliably detect thread breakage regardless of whether it is an upper thread or a lower thread.

[Means to solve the problem]

The lower thread, which is fed out to the front of the hook by a blade formed on the outer hook, is detected by a sensor installed on the hook stopper lever, and the upper thread, which is similarly hooked on the outer hook and sent out to the front of the hook by an outer hook blade, is removed. A sensor installed on a detection piece placed opposite to the outer circumferential surface of the hook detects the vibration or pressing force of the upper thread and lower thread that are periodically fed out by the rotation of the outer hook, and detects thread breakage. Make it detectable.

[Effect]

The bobbin thread is periodically paid out by the rotation of the outer hook by a sensor provided on the hook stopper lever, and the bobbin thread is similarly paid out by a sensor provided on a detection piece disposed opposite to the outer circumferential surface of the outer hook. To detect vibration or pressing force of each upper thread, and to reliably detect thread breakage of either the upper thread or the lower thread depending on the presence or absence of the vibration or pressing force. This detection means can be easily installed on existing sewing machines.

[Example] The present invention will be described below based on the illustrated example.

In the figure, reference numeral 1 denotes a bobbin case (inner hook) into which a bobbin on which a bobbin thread has been wound is inserted and supported, and this inner hook 1 is fitted into a rotating outer hook 2. The tip of a hook stopper lever 3 protruding from the sewing machine frame (not shown) is locked to a part of the inner hook so that the inner hook 1 always remains stopped when the outer hook 2 rotates. . This hook locking lever 3 is disposed so as to intersect with the upper front surfaces of the outer hook and the inner hook laterally, and a locking piece 31 protruding from the tip of this lever is inserted into a locking groove 11 formed at the upper front surface of the inner hook. It is locked. A sensor 41 is provided on the side of the engaging piece 31 of the hook locking lever. This sensor 41 detects the vibration when the outer hook 2 rotates and the blade 21 provided on the outer hook comes into contact with the bobbin thread fed out from the inner hook. Also, the upper thread is hooked on a part of the outer hook and fed out.
_N1 is a sensor 42 installed on a detection piece 6 provided on the sewing machine frame so as to face the outer circumferential surface of the outer hook, and detects the vibration or pressing force of the upper thread when it comes into contact with the detection piece. It is designed to be detected.

The sensors 41 and 42 are also configured to operate an alarm such as a warning light 53 or a bell 54 provided outside the sewing machine via the control circuit 5, as shown in FIG. The sensors 41 and 42 constantly detect the vibration of the thread when the thread is being normally fed out and the state in which the thread is broken. This is because when the upper thread and lower thread are being smoothly fed out, the outer hook rotates and the upper thread and lower thread are sequentially moved toward the outside of the front surface of the outer hook using the blades of the outer hook at a predetermined tension. It is pushed out and drawn out. The vibration or pressing force of the thread when it is pushed out by the outer hook blade 21 is detected by the sensors 41 and 42, and this signal is compared with that when the thread breaks in the control circuit 5 to determine whether or not the thread is broken. do.
That is, the control circuit 5 includes a control circuit 51 that compares the set value instructed by the setting device 55 and the novelty of the input signals from the sensors 41 and 42;
Power supply 56 and warning light 5 are controlled by output signals from
3. Alarm activation circuit 5 that operates the connection with the bell 54
2, the control circuit 51 is configured to detect a sensor input having a signal level below a set value by microcomputer program control and electronic circuitry. In normal operating conditions, the thread is periodically paid out by the rotation of the hook and comes into contact with the sensors 41 and 42, and the vibration or pressure of the thread is detected by the sensor, and this detected value is the level set value. It is as below. Therefore, there is no output from the control circuit 51 and the alarm activation circuit 52 does not operate. On the other hand, when the thread breaks, the sensor 41 or 42 detects vibrations and pressing force below a predetermined value, and the control circuit 5
1 determines that the thread is broken and issues a notification.

〔Effect of the invention〕

According to the present invention, sensors for detecting thread vibration or pressure contact force are provided on the hook stopper lever, which contacts the bobbin thread pushed out by the blades of the outer hook when the outer hook rotates, and on the detection piece, which is placed opposite to the outer circumferential surface of the outer hook. Therefore, when the outer hook rotates, the outer hook blade pushes out the upper thread and lower thread to the front of the hook.The presence or absence of vibration or pressure is detected when the upper thread and lower thread are fed out, and the presence or absence of vibration or pressure is detected by comparing the vibration or pressure when the thread breaks. It has the advantage of being able to reliably detect.

[Brief explanation of the drawing]

FIG. 1 is a front view, FIG. 2 is a plan view, FIG. 3 is an explanatory diagram, and FIG. 4 is an embodiment of the control circuit. 1 is an inner hook, 11 is a locking groove, 2 is an outer hook, 21 is a blade, 3 is a hook stopper, 31 is a locking piece, 41, 42
is a sensor, 5 is a control circuit, 6 is a detection piece, N1 is an upper thread, and N2 is a lower thread.

Claims (1)

[Claims] 1. The bobbin thread, which is fed out to the front of the hook using a blade formed on the outer hook, is brought into contact with the sensor provided on the hook stopper lever, and the upper thread, which is similarly hooked on the outer hook and sent out to the front of the hook by the outer hook blade, is brought into contact with the sensor provided on the hook stopper lever. is brought into contact with a sensor provided on a detection piece disposed opposite to the outer circumferential surface of the outer hook, and this detects the vibration or pressing force of the upper thread and lower thread that are periodically paid out by the rotation of the outer hook. is individually detected by the sensor,
A method for detecting thread breakage in a sewing machine, characterized in that thread breakage of upper and lower threads is detected.