Sewing – Elements – Thread cutting – severing or breaking
Patent
1990-05-31
1992-05-19
Schroeder, Werner H.
Sewing
Elements
Thread cutting, severing or breaking
112254, D05B 6500, D05B 4700
Patent
active
051137747
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention pertains to a thread cutting device for sewing machines with a thread catcher. The thread catcher being actuated by an axially moveable drive mechanism to perform a first movement step catching the needle thread and the shuttle thread, and a second movement step whose direction is opposite to the first movement step in which the threads are pulled out and fed to a stationary cutting blade. A thread tensioning mechanism is provided for the needle thread and a releasing member for opening the thread tensioning mechanism during the thread pull operation. The releasing member being actuated by a cam rigidly attached to the drive mechanism.
BACKGROUND OF THE INVENTION
A thread cutting device, in which an axially displaceable drive mechanism catches the needle thread and the shuttle thread in one of its directions of movement and pulls them out and feeds them to the cutting blade in its other direction of movement, has become known from a realized sewing machine design. To control the releasing mechanism for the thread tension, a cam actuating the release mechanism is fastened on the drive mechanism. Even though this measure ensures a very simple drive of the tensioning mechanism, it causes opening of the thread tensioning mechanism during the movement of the drive mechanism in both directions of movement. This leads to difficulties in catching the loop under critical thread conditions and also to unequal thread ends after the cutting process.
SUMMARY AND OBJECTS OF THE INVENTION
It is an object of the present invention to design the releasing mechanism for thread tensioning in a thread cutting device with a thread catcher actuated by an auxiliary moveable drive mechanism which performs a first movement step catching the needle thread and the shuttle thread and a second movement step whose direction is opposite to the first movement step wherein the threads are pulled out and fed to a stationary cutting blade. A thread tensioning mechanism is provided for the needle thread and a releasing member for opening the thread tensioning mechanism during the thread pull operation. The releasing member being actuated by a cam rigidly attached to the drive mechanism so that the thread tensioning mechanism is opened only during the afterpull of the needle thread.
According to the invention, a thread cutting device is provided for sewing machines with a thread catcher. The thread cutting device being actuated by an axially moveable drive mechanism. The thread catcher performs a first movement step catching the needle thread and the shuttle thread and a second movement step whose direction is opposite to that of the first movement step in which the threads are pulled out and fed to a stationary cutting blade. A thread tensioning mechanism is provided for the needle thread and a releasing member is provided opening the thread tensioning mechanism during the thread pull operation. The releasing member can be actuated by a cam rigidly attached to the drive mechanism. A one way coupling is provided for the releasing member which is in action during the second movement step of the drive mechanism, the one way coupling being provided between the drive mechanism and a linkage connected to the releasing member.
With the control according to the present invention, the thread tensioning mechanism now remains closed during the penetration of the thread catcher into the needle thread loop, so that the stability of the loop is preserved when it is being caught by the thread catcher. The thread tensioning mechanism is opened only at the beginning of the afterpull of the needle thread and closes only when no more thread is pulled.
An embodiment of simple design of the one-way coupling is provided according to the invention in which the one-way coupling has a lever yielding in one direction. The lever pivoting during the first movement step of the drive mechanism and remaining rigid during the second movement step of the drive mechanism.
The measure according to the invention in which the c
REFERENCES:
patent: 3141432 (1964-07-01), Reeber et al.
patent: 3173392 (1965-03-01), Hedegaard
patent: 3386402 (1968-06-01), Ross
patent: 4254725 (1981-03-01), Hager et al.
patent: 4365568 (1982-12-01), Ross
patent: 4455957 (1984-06-01), Vollmar
patent: 4471707 (1984-09-01), Astrupgaard
patent: 4611547 (1986-09-01), Kuramato
patent: 4694765 (1987-09-01), Diehl
Dusch Albert
Walter Karl-Heinz
Lewis Paul C.
Pfaff Industriemaschinen GmbH
Schroeder Werner H.
LandOfFree
Thread cutting device on a sewing machine does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Thread cutting device on a sewing machine, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Thread cutting device on a sewing machine will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2412243