Winding – tensioning – or guiding – Strand tensioning device – Clamp
Patent
1992-06-05
1994-11-29
Gilreath, Stanley N.
Winding, tensioning, or guiding
Strand tensioning device
Clamp
242154, B65H 5924, B65H 5934
Patent
active
053682440
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention refers to a thread brake, and more particularly, to a thread brake which permits automatic threading of a thread.
BACKGROUND OF THE INVENTION
In a thread brake, the thread passing through the brake is mechanically decelerated by means of squeezing and/or deflection. The thread brake constitutes a weak point in the thread path when threading is carried out for the first time or when it is carried out after thread breakage because the thread has to be threaded by hand in some cases through a plurality of thread brakes, and this is time-consuming and complicated. The advantages with regard to ease of handling and stop periods gained by an automatic threading device provided for other components along the thread path are substantially impaired by the manual threading operation in the thread brakes.
This applies to the lamella brakes according to U.S. Pat. No. 4,641,688 or DE-A-21 31 302, in the case of which two lamellae are resiliently pressed against each other or in the case of which one lamella is pressed against a fixed stop means, as well as to the known socalled deflection brakes in the case of which thread guide elements are manually aligned with respect to each other by folding two holding arms towards one another before the thread is threaded by hand.
In the case of a controlled thread brake known from CH-A-310 476, a brake element is pressed against a counter brake element consisting of a tensioned braking strip. The brake element is connected to a cam drive means and it is even adapted to be completely lifted off the counter brake element.
WO 90/11397 describes that cam-controlled thread tensioners and thread brakes with cam-controlled braking fingers are displaced to a threading position for the purpose of threading the thread. However, this arrangement does not comprise any air guide surfaces.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to provide an improved thread brake, which permits automatic threading of the thread. For carrying out the first threading operation or for carrying out a threading operation after thread breakage, the thread brake will be displaced to the threading position and a stream of air will be produced in the air guide passage, said stream of air threading the end of the thread automatically through the thread brake. The threading operation is carried out automatically with little expenditure of time. The stream of air can be produced either within the thread brake or outside thereof. The air guide surfaces prevent a lateral deviation of the stream of air as well as of the thread, and they guarantee that the free end of the thread flies through the thread brake rapidly and without getting entangled.
A preferred variation, the drive means is capable of adjusting the threading position on the one hand and of modulating the braking effect on the other. If desired, this can be done by remote control or automatically.
The case of the embodiment according to claim 5, the drive means displaces brake elements in both directions. This will be expedient with regard to a rapid start of operation after threading because the drive means will readjust the thread brake to a predetermined braking effect.
When a thread breakage detector detects thread breakage, the drive means will move the thread brake to the threading position. A pressure source will generate a stream of air which will thread the thread end. As soon as the thread breakage detector detects that the thread is present, the threading position will be given up and the pressure source will be deactivated. The thread brake is again ready for operation without delay.
The automatic threading operation is initiated upon actuation of the drive means. This can be done by remote control. Manual actuation is imaginable as well.
The air guide surfaces are provided for effecting automatic threading by means of the stream of air.
The brake elements are annular thread eyes provided with axial extensions which form a largely closed air guide passage. Th
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Jacobsson Kurt A. G.
Melillo Michele
Gilreath Stanley N.
Iro AB
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