GB2235702A

GB2235702A - Thread-breakage detector for spinning and doubling frames

Info

Publication number: GB2235702A
Application number: GB9019484A
Authority: GB
Inventors: Bernhard Schonung; Alfred Glock
Original assignee: SKF Textilmaschinen Komponenten GmbH
Current assignee: SKF Textilmaschinen Komponenten GmbH
Priority date: 1989-09-08
Filing date: 1990-09-06
Publication date: 1991-03-13
Also published as: IT9021411A0; JPH03104944A; FR2651801A1; DE3929895A1; GB9019484D0; DE3929895C2; JPH072621Y2; IT1246267B; FR2651801B1; CH681814A5; IT9021411A1; JPH0589470U

Abstract

The fitting of traditional thread-breakage detectors either involves considerable labour and expense or the devices themselves hamper the operation of the frame. A thread-breakage detector is disclosed which comprises a screened insulating housing (1) with a pair of electrodes (2), conducting members (3) and AC amplifiers (4) inside. Fitting and locking of the housing (1) to the thread guide (6) in the proximity of the thread is made possible by a clamping device (5). After one fitting operation the thread-breakage detector is automatically moved whenever the thread guide (6) is readjusted to the centre of the spindle, enabling maintenance work on the 90 thread-breakage detector to be kept to a minimum. <IMAGE>

Description

1..._ f-- - - 4 THREAD-BREAKAGE DETECTOR FOR SPINNING AND DOUBLING FRAMES

This invention refers to a thread-breakage detector for spinning and doubling frames with one pair of open electrodes located in close proximity to the running thread and provided with totally electrostatically screened conducting members connected to corresponding AC amplifiers.

It serves-to monitor the running thread and, should this break, signals the fact to a display and cut-off device.

There are already various contact-free thread-breakage detectors or sensors as, for instance, that described in DE-A-37 20 602. By comparison with others, the thread-breakage detector illustrated there has the advantage that it is open to the thread and requires no addition,-il threading.

Among the disadvantages of familiar thread-breakage detectors, however, is the fact that they are awkward to fit onto spinning frames and have to be exactly adjusted to the thread position. Both the manufacture and the fitting of thread-breakage detectors pose problems. With some 600 to 1000 spinning points on each machine to be so equipped, the manufacture, fitting and adjustment of thread-breakage detectors is unjustifiably costintensive by comparison with the results.

The subject of this invention is a thread-breakage detector of the type mentioned at the outset which can be fitted universally and in a spacesaving way, and is also simple to retrofit to existing frames. Advantageously it should be capable of being fitted with precision to each spinning point. Its construction and fitting should preferably make for a long service life and minimum maintenance, avoiding as far as possible accumulations of dirt or fly.

The invention is characterised in that the electrodes, conducting members and AC amplifiers are protected inside a screened, insulated housing, that this housing_is-rigidly fixed by means of a clamping device on a thread guide in such a way that, once fitted, it can always be jointly adjusted together with the thread guide, and that the screening of the housing is open on the side of the electrodes in the direction of the thread.

A thread-breakage detector according to the invention may employ a cheap, small, metallised plastics housing as a component of the thread-breakage detector. The latter and its housing can be precisely fitted in its operating position close to the thread; this operating position is maintained even after the thread guide has been raised several times. Furthermore, the locking on the thread guide obviates the need for renewed adjustment of the thread-breakage detector once the thread guide has been set to the middle of the spindle. The joint adjustment of thread guide and screw-fitted thread-breakage detector can be supported on the thread board by means of an adapter in which the housing of the thread- breakage detector is capable of sliding. In addition, the adapter enables just one housing to be used for many types of frame. The minimisation of the thread-breakage detector and of the amount of fitting it requires by 1 t means of a small housing avoids encumbrances to staff operating the frame and prevents troublesome dirt from accumulating on the electrodes.

The pairwise arrangement of the electrodes in connection with downstream AC amplifiers avoides possibly disadvantageous electrical features of the arrangement by comparison with thread-breakage detectors with enclosed electrodes between which the yarn has to be threaded. The common accommodation of the electrodes,-conducting members and AC amplifiers in the housing of the thread-breakage detector reduces costs, simplifies fitting and provides the most favourable signal-to-noise ratio. The response sensitivity of the thread-breakage detector is adjustable.

In the accompanying drawings:

Figure 1 shows a thread-breakage detector retro-fitted to a thread guide and thread board of a spinning frame, and Figure 2 shows details of the thread-breakage detector and a pigtail thread-guide.

The housing 1 of the thread-breakage detector is rigidly fixed to a thread guide 6 in its groove 8 by means of a clamping bracket 5. A thread 7 runs through the thread guide 6 close to the front of the housing 1 on which a pair of electrodes 2 are positioned beside one another and on towards a spindle 16. The distance between the thread-breakage detector and the thread 7 only has to be adjusted once. The thread guide 6 possesses an aid to adjustment in the form of the groove 8, which also 1 simplifies the fitting or exchange of the thread-breakage detector without the necessity for new adjustment. Neither the readjustment of the thread guide 6 to the centre of the spindle nor frequent raising of the thread board 10 affect the once-adjusted position of the thread-breakage detector as they would in the case of traditional detectors. The rigid securing of the housing 1 on the thread guide 6 guarantees the essential simplification of the thread-breakage detector and without whichthe great number (600.... 1000 depending on the frame type) of thread-guide readjustments possibly required would mean an unreasonable number of readjustments of the thread-breakage detectors. once the housing 1 of the thread-breakage detectors has been fitted,.the reaction time and/or response sensitivity of a large number of thread-breakage detectors can be controlled by a control device (not shown).

The exterior of the insulating housing 1 is, with the exception of its front, metallised. Contact between this layer and the earthed thread guide 6 and the thread board 10 provides good screening for the thread- breakage detector. After installation, the metallic thread board 10 also screens the thread-breakage detector from the top. Possible interference at the front of the housing 1 is electrically eliminated by the pair of electrodes 2 with their corresponding AC amplifiers (differential amplifiers) 4. The conducting members 3 for the electrodes 2 and the AC amplifiers 4 can be fitted to a common baseplate 13 with which they can be simply fitted into the housing 1 and then either cast or glued into place. One version provides for two openings 15 at the front of the housing into which 1 the electrodes 2 secured on the baseplate 13 snap into place with grooves 14 for the conducting members 3. The version shown provides for the guidance of the housing 1 on the thread board 10 of a machine-specific adapter 9 in which the housing 1 can be slid. on the back of the housing 1 or of the adapter 9 openings are provided at the side with mains lead cleats 11 for the evaluation wires 12 to prevent damage to the evaluation wires 12 during the pivoting of the thread board 10.

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Claims

Thread-breakage detector for spinning and doubling frames with one pair of open electrodes (2) located in close proximity to the running thread (7) and provided with totally electrostatically screened conducting members (3) connected to corresponding AC amplifiers (4) characterised in that the electrodes (2), conducting members (3) and AC amplifiers (4) are protected inside a screened, insulated housing (1), that this housing (1) is rigidly fixed by means of a clamping device (5) on a thread guide (6) in such a way that, once fitted, it can always be jointly adjusted together with the thread guide (6), and that the screening of the housing (1) is open on the side of the electrodes (2) in the direction of the thread (7).
2. Thread-breakage detector as claimed in Claim 1, characterised in that the clamping device (5) on the housing (1) is a bracket and the thread guide (6) is provided with a groove (8) for locking the bracket.
3. Thread-breakage detector as claimed in Claim 1 or 2, characterised in that a machine-specific, screened adapter (9) is fitted on a thread board (10) to guide the housing (1).
4. Thread-breaking detector as claimed in any preceding claim, characterised in that the housing (1) or the adapter (9) has rearward exit openings with mains lead cleats (11) for supply and evaluation wires (12).
5. Thread-breakage detector as claimed in any preceding claim, characterised in that the electrodes 21 1 (2), conducting members (3) and AC amplifiers (4) have a common baseplate (13) on which they can be inserted into the housing (1).
6. Thread-breakage detector as claimed in Claim 5, characterised in that grooves (14) are provided in the housing (1) for the conducting members (3), which grooves run from the electrodes (2) on the front of the housing (1) to the baseplate (13) in the housing 10 (1) -
7. Thread-breakage detector as claimed in any preceding claim, characterised in that openings (15) or gluing points are provided on the front of the housing (1) for securing the electrodes (2).
8. Thread-breakage detector as claimed in claim 3, characterised in that the electrostatic screening of the housing (1) is connected to ground via contacts with the thread board (10).
9. A thread-breakage detector substantially as herein described with reference to and as shown in the accompanying drawings.

Published 1991 at Ile Patent Office. State House. 66171 HiahHolborn. IA)ndonWC I R 417. Further copies may be obtained from