EP1377513B1 - Thread detector - Google Patents

Abstract

The invention relates to a thread detector (F) for detecting thread path/halt conditions and/or thread tension. Said detector is provided with a deflector assembly for re-directing the thread, said assembly transmitting the stress on the thread to at least one transducer device (W), which generates a signal and responds to mechanically transmitted stresses. The deflector is also provided with at least one electronic evaluation circuit (6) for deriving output signals, (i1, i2) and with thread guides (8), which are located upstream and downstream of the deflector assembly and define the course of the thread. The deflector assembly comprises a first and second deflector (D1, D2) that lie one behind the other in the course of the thread, one of Which transmits the stress from the thread tension and the other the stress from the path/halt conditions to a respective transducer device (W). The deflectors having first and second re-direction surfaces (9, 10), positioned transversely in relation to the thread axis, which together form an angle of <180°, (when viewed from the thread axis), whereby said re-direction surface share the deflection of the thread.

Description

The invention relates to a thread detector according to the preamble of patent claim 1.

An example of a place of use of such a thread detector is the thread path between a weft thread delivery device and the shed of a weaving machine. For Control operations of all kinds become information about the current Thread tension of the resting or running thread and additional weft monitor information needed over thread running / stopping conditions.

From DE 43 23 748 A it is known to perform both functions by means of a single thread detector to be fulfilled, in which the thread has a piezo element via a single deflector acted upon, which is connected to a control unit for signal transmission. The braking force is, for example, measured by means of the permanently measured thread tension a weft brake adapted to the weft insertion conditions and from a strong drop in thread tension a weft break (weft monitor function) derived.

In the weft thread detector known from DE 31 10 462 A for the weft thread monitoring function the thread tension is also scanned, by means of a single deflector and a single one, for example piezoelectric Converter. An equivalent weft monitor for both functions is also out US 4,228,828 A is known.

In the thread detector known from EP 0 357 975 A, a single one is used by one Deflector-applied sensor of a weft monitor also serves as the thread tension sensor used to control a thread brake.

DE-A-100 00 232 relates to a measuring device for thread tension measurement by a thread.

Further prior art for thread tension measurement is contained in EP 0 605 550 A, EP 0 574 062 A, US 3 300 161 A, W097 / 13131.

Clear and meaningful output signals for the two functions (thread tension measurement and scanning of thread running / stopping conditions) are with a single Deflector can only be obtained with relatively high electronic effort, which is too high Costs of the thread detector and its susceptibility to faults, because the prerequisites for monitoring the thread running / stopping conditions are different from the requirements for measuring the thread tension.

The invention has for its object a thread detector of the aforementioned Way of creating the information required in other ways and determined better adapted to the respective conditions, with less mechanical Derives load for the thread, inexpensive and reliable to manufacture and a very wide range of applications (for different types of thread processing Systems or weaving machines and delivery devices and all used in practice Thread qualities) is able to cover.

The object is achieved with the features of claim 1.

Each deflector feels the thread with regard to a special requirement and for the task assigned to him (thread tension measurement and / or running / stopping conditions) optimally. For this reason alone, every deflector can with a relatively simple converter device tailored to the respective function cooperate. If one function fails, the other function remains unaffected receive. Since the two deflectors divide the thread deflection among themselves and like a single positive thread guide, a kind of two-dimensional thread guide, act, the mechanical load on the thread is moderate and sufficient an overall deflection that is significantly less than the sum of the deflections in two completely separate devices for one function each. By the angle less than 180 ° between the deflection surfaces can be any deflection surface despite a small deflection angle from the thread load a force component to press the thread against the other deflection surface, which improves responsiveness without unduly stressing the thread. Due to the selected geometry, each deflector takes just as much of that Thread loading as appropriate for the function assigned to it.

The two deflectors are expedient in the thread path directly and without contact adjacent, so that generated on at least one deflection surface from the load Force as effective as possible directly on the deflecting surface of the other deflector becomes. In addition, the mutual proximity of the deflectors has the advantage that they act together as a single two-dimensional thread guide and the current one Stabilize the thread effectively, which is favorable for the scanning accuracy.

The angle between the deflection surfaces should be at least essentially 90 °. This ensures clean guidance of the running thread.

Is at least the deflecting surface of a deflector in the direction of orientation Deflection surface of the other deflector transverse to the thread axis with respect to the Staggered thread path, then the degree of displacement determines the deflection of the thread in the thread detector. The deflecting surfaces are preferably both Deflectors offset from the straight thread path, so that the thread each exerts the necessary loads on both deflection surfaces for scanning.

An inclined angle at least of the deflection surface of a deflector is particularly important in relation to a plane that is defined by the fictitious straight thread path and the actual thread path is defined. This inclination is set so that from the Thread loading on the inclined deflection surface is a sliding force component to the deflecting surface of the other deflector is generated. This will make the deflection surface of the other deflector not only with the reaction force from the deflection of the Thread, which can be low there, but also due to the sliding force component applied. This arrangement allows a relatively small overall Set the total deflection angle for the thread, which is gentle on the thread.

An inclination angle of about 70 ° with respect to the plane mentioned is for one Deflection surface cheap. With a 90 ° crossing of both deflectors, this is then Oblique angle with respect to the same plane of the other deflector is approximately 20 °. This Angles can be varied. The deflector, its deflecting surface, is expedient forms the inclined angle of approximately 70 ° with the plane for thread tension measurement responsible. Because the thread tension can be more sensitive determine if the thread is a significant part of the resulting from the thread tension Exerts a load on this deflector. For monitoring the thread run / stop conditions a smaller angle of inclination is sufficient at the other deflector, because those to be sampled for meaningful information on the run / stop conditions Loads are dominant from friction and vibration loads, for which the contact pressure of the thread can be less or differently oriented than for the thread tension measurement.

Technically simple, reliable and for practically all thread qualities deflectors in the form of rods or tubes are suitable. Same outside diameter are useful but not mandatory. Ceramic material has the advantage of high wear resistance and a certain internal damping with low Weight.

The deflectors, which operate separately, are each arranged on a transducer element, that is stationary supported. It is useful to use the deflectors with their To attach the foot area to the transducer element, so that the loads on the thread be transmitted with a priced lever arm and unadulterated. Especially Piezoelectric or photo-elastic transducer elements are expedient because these Deliver meaningful useful signals with moderate control effort. alternative could also use inductive, triboelectric or other transducer elements or strain gauges directly on the deflectors.

The construction effort remains low if every piezoelectric transducer element in a film chip is integrated, which is also at least part of the evaluation circuit contains.

A fluoroscopic photo-elastic transducer element changes its optical properties depending on its deformation or its internal state of tension. The intensity of the emerging light varies within a wide range and delivers meaningful signals that are easy to pick up and optoelectronic are evaluable.

The photoelastic transducer element is expediently a plate made of a transparent one Plastic such as polycarbonate (or an optical glass) that is at least one-sided, preferably both ends, clamped and almost exclusively from the deflector Torsion is applied. This material is largely in a stress-free state isotropic and becomes with increasing internal tension, e.g. a torsional stress, anisotropic. This change is due to the optoelectronic scanning device followed and as an output signal, for example, representative of the thread tension delivered, and without any significant reinforcement or conditioning effort. The optical axis of the scanner should be the plate penetrate perpendicular to their surfaces.

With isochromatic light, e.g. Red light from an LED, becomes the photo-elastic element X-rayed, with polarizing elements on the input and output sides with one another crossing polarization axes are used to set a position in which almost no light is emitted when the element is not under load and with increasing internal tension the intensity of the emerging light after a Function increases, which even linearizes with simple control technology can be. The variation in the intensity of the emerging light can e.g. with a Photo transistor can be tapped.

An embodiment of the thread detector with a base body is structurally simple, a storage for the converter devices and the deflectors as well as the thread guides contains. The deflectors should cross each other without contact. The Storage advantageously has an inclined position about the thread axis, so that the load on the thread on the at least one deflector increased contact pressure against the deflection surface of the other deflector and the response behavior of the thread detector increases, so that overall a small deflection angle in Thread detector can be selected.

The storage is even expediently adjustable in order to adapt to the respective To be able to carry out working conditions or thread qualities.

Fig. 1

eine Perspektivansicht eines Fadendetektors,

Fig. 2, 3, 4

drei Schemadarstellungen von Detailvariationen zum Fadendetektor der Fig. 1, und

Fig. 5

einer weitere Detailvariation in perspektivischer Schemaansicht.

Embodiments of the subject matter of the invention are explained with reference to the drawing. Show it:

Fig. 1

a perspective view of a thread detector,

2, 3, 4

three schematic representations of detail variations to the thread detector of FIG. 1, and

Fig. 5

a further detail variation in a perspective schematic view.

A thread detector F in FIG. 1 is intended for use in thread processing systems, for example for use in the thread path between a weft thread delivery device and a weaving machine. With the thread detector F you can choose here the thread tension measured and / or the thread running / stopping condition of the Weft thread to be monitored. Each function is carried out independently. If necessary, one of the two functions can remain unused without the other Impair function. Of course, both functions can be permanent be carried out side by side.

The thread detector F in FIG. 1 has a base body 1, in which in FIG molded receptacles 3 a storage 2 for two transducer assemblies W mounted is. A bridge-like holder 7 supports two thread guides 8 which pass through the thread path define the thread detector F. 4 with a surface of the holder 7 is designated, which are assumed to be a horizontal reference plane for easier explanation can.

In each transducer arrangement W, a transducer element 20 is stationary, e.g. on piezoelectric transducer element or a photoelastic transducer element. To the Transducer elements 20 are a first deflector D1 and a second deflector D2, respectively cantilevered on one side, e.g. in the form of a round bar or tube 5, for example made of ceramic material. The transducer elements 20 are connected to one electronic evaluation circuit 6 connected, from the output signals i1, i2 to be delivered. The evaluation circuit 6 can be accommodated in the base body 1.

Optionally, the transducer elements 20 are integrated in film chips, which at least already contain part of the evaluation circuit. The two deflectors D1, D2 are arranged one behind the other in the thread path, without each other to touch. Each deflector D1, D2 forms a deflecting surface 9, 10 for the supported by the thread guide 8 thread Y. The deflecting surfaces 9, 10 close with each other an angle β, which is illustrated by the bearing 2, e.g. one Angle of about 90 °. The thread Y is between the thread guides 8 on both deflection surfaces 9, 10 deflected.

Defines the actual, deflected and solid line path shown with the fictional, stretched and dash-dotted thread path one level E. At least the deflecting surface 9 oriented transversely to the thread axis is opposite the Level E inclined at an oblique angle χ, also symbolized by the angle α between the axis of the deflector D1 and the surface 4. The second Deflector D2 can be oriented vertically to surface 4 or, as shown, with a Crossing angle β of approximately 90 ° to the first deflector D1 also with the bearing 2 in Fig. 1 to the top right. The bank angle χ can for example by an adjusting device 22 in the base body 1 on the bearing 2 be changed as needed.

The deflector D1 with its transducer element W is useful for measuring the Thread tension. Deflector D2, on the other hand, is used to monitor the faderil / stop conditions. The first and second deflection surfaces 9, 10 share the overall deflection of thread. The deflection surface 9 are more strongly impacted by the thread Y than the deflecting surface 10.

2 to 4 illustrate different variants of the relative positioning the first and second deflectors D1, D2 in relation to the thread guides 8.

2, the first and second deflecting surfaces 9, 10 on both deflectors D1, D2 compared to the fictitious stretched thread path defined by the thread guide 8 offset, so that in the angular bend between the two deflection surfaces 9, 10 guided and deflected at both deflecting surfaces 9, 10 from its Load on the deflectors D1, D2 at least in the direction of orientation first deflection surface 9 directed sliding force component K to the other deflection surface 10 developed that increases the contact pressure on the other deflecting surface 10. On thread section 11 of the thread Y extending to the first deflection surface 9 2 upwards and slightly to the left, is deflected at the first deflection surface 9, then changes over to the second deflection surface 10. The thread Y is on the deflected the second deflecting surface 10 and against it also with the component K pressed, and runs with a running section 12 to the other thread guide 8th.

In Fig. 3, the second deflection surface 10 is vertically aligned with that through the thread guide 8 defined stretched thread path arranged. The first deflection surface 9 is below the tilt angle χ tilted to the right relative to the plane E, so that the deflected tapering thread section 11 from the load on the first deflection surface 9 developed a rightward sliding force component K, which additionally presses against the second deflection surface 10.

4, the two deflectors D1, D2 are at an intersection angle with one another of about 90 °. The first deflector D1 is with the bank angle χ (for example 70 °) slanted to the right relative to plane E, so that the tapering thread section 11 on the first deflecting surface 9 the sliding force component K developed to the right to the second deflection surface 10 and the expiring Thread section 12 presses against the second deflection surface 10. The running thread section 12 is also due to the oblique position of the second deflector D2 redirected this.

5, as the transducer arrangement W, for example, the deflector D1 is a photo-elastic one Transducer element 20 indicated. This has the shape of a thin, elongated one Plate 13 and consists of photo-elastic material, such as plastic or optical glass, which, for example, largely in a voltage-free state is isotropic. With increasing internal tension, this material changes its optical Properties e.g. towards anisotropic, what about using fluoroscopy, for example isochromatic light can be converted into a clear output signal.

The intensity of the emerging light changes and can be scanned to initially towards the tension condition and thus indirectly towards the thread tension conclude.

The plate 13 is clamped stationary at 14 at both ends, for example. The Deflector D1 is attached to the plate 13 and cantilevered freely on one side, so that the Thread Y applied to him in the plate 13 produces pure torsion, i.e. inner Torsional stresses. Between the attachment of the deflector D1 and a clamping 14, an optoelectronic scanning device T is provided with which the Change in the optical properties of the plate 13 with fluoroscopy (or reflection) is tapped. The optoelectronic scanning device T has an optical one Axis 21 which penetrates the plate 13 approximately perpendicular to its surfaces 17. On one side of the plate 13 there is a light source 15 in the optical axis 21, e.g. placed a red light LED which e.g. emits at least quasi-isochromatic light

In front of the surface 17 of the plate 13 is a first polarizing element 16 with one in the Placed direction set linear polarization axis. At the opposite Surface 17 of plate 13 is a second polarizing element 18 placed so that its linear polarization axis is the polarization axis of the first polarizing element 16 crosses. In the light path behind the second polarizing element 18 is a Receiver 19 placed, for example a photo transistor. The relative positions of the Polarizing elements 16, 18, possibly also relative to the optical light transmission axis the plate 13, e.g. set so that in a de-energized state no light emerges from the plate 13 since the light waves, e.g. because of the birefringence effect the polarizing elements, extinguish. With increasing internal torsional tension in the plate 13, caused by the loading of the thread Y on the Deflector D1, the intensity of the emerging light grows according to a mathematical Function, e.g. with the square of the torque applied by deflector D1, what the receiver 19 registers. By comparison with the emitted Light, or directly, an output signal, e.g. i1, representative of the current thread tension supplied.

In the described embodiments, the two deflectors D1, D2 are included straight deflection surfaces formed transversely to the thread axis. The deflection surfaces could also be concave or convex curved. The two deflectors must also be used D1, D2 should not be immediately adjacent. There could be a small gap be set, or vice versa even a spatial overlap between the two Deflectors, e.g. through corresponding cutouts in the deflectors so that the whose two deflection surfaces 9, 10 are moved closer together than shown. The angle included between the two deflecting surfaces 9, 10 could also be used also be significantly smaller than 90 ° or larger than 90 °, but not larger than 180 °. A total deflection angle of ± 15 ° for the thread is sufficient for most thread qualities to precisely measure the thread tension and the thread running / stopping conditions to be able to monitor. Each function can be switched on or off individually become. The failure of one function affects the other function Not.

Claims (14)

1. Thread detector for detecting thread running/stop conditions and/or the tension in the thread, comprising a deflector assembly for deflecting the thread, at least one signal generating converter assembly (W) mechanically actuated by the deflector assembly and responding to loads exerted by the thread or the deflector assembly, at least one electronic evaluation circuitry (6) for deriving output signals (i1, i2), and stationary thread guides (8) arranged upstream and downstream of the deflector assembly, for defining a thread path through the thread detector, characterised in that the deflector assembly includes a first deflector (D1) and a second deflector (D2) arranged in the thread path one behind the other, that a respective converting assembly (W) is associated to each deflector, that the first and second deflectors (D1, D2) comprise first and second deflection surfaces (9, 10) each oriented crosswise to the axis of the thread, and that the deflection surfaces (9, 10) include an angle (β) smaller than 180° with each other seen in the direction of the axis of the thread, and share the total thread deflection among each other.
2. Thread detector as in claim 1, characterised in that the first and second deflectors (D1, D2) are placed closely adjacent and without contact in the thread path.
3. Thread detector as in claim 1, characterised in that the angle (β) at least amounts to about 90°.
4. Thread detector as in claim 1, characterised in that the deflection surfaces (9, 10) are offset with respect to a fictive stretched thread path defined by the thread guides (8) respectively in the direction of the orientation of the respective other deflection surface and crosswise to the axis of the thread.
5. Thread detector as in claim 1, characterised in that the fictive stretched thread path defined by the thread guides (8) and the actual thread path deflected over the deflectors (D1, D2) commonly define a plane (E), and that at least the deflection surface (9) of one of the deflectors (D1) is provided with inclination position angle (X) inclined by its orientation crosswise to the axis of the thread in and relation to the plane (E) such that the thread load exerted at this deflection surface (9) generates a sliding force component (K) in the thread which sliding force component (K) is directed against the deflection surface (10) of the other deflector (D2).
6. Thread detector as in claim 5, characterised in that the inclined position angle (X) of the deflector (D1) amounts to about 70°, and that, preferably, the other deflector (D2) deflection surface (10) includes an inclined position angle of about 20° with the plane (E).
7. Thread detector as in claim 1, characterised in that both deflectors (D1, D2) are round rods or tubes (5) having substantially equal outer diameters, that the rods or tubes (5) are supported at one end respectively, and that the rods or tubes (5), preferably, consist of ceramic material.
8. Thread detector as in claim 1, characterised in that each deflector (D1, D2) is arranged at a stationarily provided converter element (20) of its converter assembly (W).
9. Thread detector as in claim 8, characterised by a piezo-electric or photo-elastic converter element (20).
10. Thread detector as in claim 1, characterised in that the piezo-electric converter element (20) is integrated into a film chip.
11. Thread detector as in claim 9, characterised in that the photo-elastic converter element (20) is formed with a plate-shape from a transparent material like polycarbonate, that the plate-shaped converter element (20) at least at one side (14) is secured in a and is actuated by the deflector (D1) for torsion, and that an opto-electronic scanning device (T) is provided for the interior stress condition of the converter element, the scanning device (T) having an optical axis (21) penetrating the converter element (20) substantially perpendicular to the plate surface (17).
12. Thread detector as in claim 11, characterised in that the opto-electronic detection device (T) includes a light source (15), preferably for generating isochromatic light or red light, polarisation elements (16, 18) at both sides of the converter element (20), the polarisation elements (16, 18) having respectively crossing polarisation axes, and a photo-element serving as a receiver (19).
13. Thread detector as in at least one of the preceding claims, characterised in that a support (2) is provided in a base body (1), the support (2) having sockets (3) for the two converter assemblies (W), the sockets (3) being inclined to each other with an angle of about 90°, that two thread guides (8) are secured to the base body (1) for defining the thread path, that both deflectors (D1, D2) protrudes from the support (2) and extend crosswise through the thread path and cross each other with an angle smaller than 180°, preferably of about 90°, and that the support (2) has an inclined position relative to a plane (E) and about the thread axis, which inclined position is defined by the fictive stretched thread path between both thread guides (8) and the actual deflected thread path over both deflectors (D1, D2).
14. Thread detector as in claim 13, characterised in that an adjustment device (22) for the inclined position of the thread detector (F) is provided, preferably an adjustment device for the support (2) within the base body (1).

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