EP0789097A1 - Method and apparatus for measuring warp tension in a weaving loom - Google Patents

Abstract

A method of measuring warp tension in a loom entails leading the warp over a deflecting agent and a spring loaded tensioner which is caused to swivel about a pivot by warp action. A force sensor is attached to the tensioner to measure the force, F(M), transferred to it. This force is essentially the same over the swivel arc depending on the run of the warp and the geometrical arrangement of the deflecting agent, tensioner and pivot point. Also claimed are: (i) the apparatus for implementing the method comprising the deflecting agent (3), tensioner (15), pivot (16) and force sensor (25) which has a surface which deflects under pressure and at least one measuring element fixed to the face, wherein the force sensor and tensioner are so located to one another that the normal to the pressure-receiving surface and line of action of the force F(M) point in the same direction; and (ii) a loom using the apparatus which is then followed by a warp beam.

Description

The invention relates to a method for measuring the tension of a warp in a weaving machine according to the preamble of claim 1 and a device for carrying out the method according to claim 4.

The warp threads are more or less deflected by the heald frames within a weaving cycle, so that tension fluctuations occur in the warp threads. To compensate for the fluctuations, i.e. To keep the tension in the warp threads as constant as possible, the spring-loaded tensioning tree performs a swiveling movement.

An analysis of the forces acting on the spanning tree shows that the resulting force and the partial forces change during the swiveling movement.

It proves to be disadvantageous that large deviations occur even at relatively small swivel angles, which in regulations have to be compensated for with considerable additional effort.

The invention seeks to remedy this. The invention, as characterized in the claims, achieves the object, a method and an apparatus for measuring to create the tension of a warp, whereby the deviations are kept within narrow limits and the measured values are provided with little effort for direct inclusion in a regulation.

The invention is explained below with reference to the accompanying drawings.

Fig. 1

Ein schematisch dargestellter Verlauf der Webkette und des Gewebes in einer Webmaschine;

Fig. 2

eine schematische Darstellung der auf das Spannorgan einwirkenden Kräfte;

Fig. 3

eine erste Ausführungsform einer erfindungsgemässen Vorrichtung;

Fig. 4

eine zweite Ausführungsform einer erfindungsgemässen Vorrichtung;

Fig. 5

eine dritte Ausführungsform einer erfindungsgemässen Vorrichtung und

Fig. 6

eine vierte Ausführungsform einer erfindungsgemässen Vorrichtung.

Show it:

Fig. 1

A schematically illustrated course of the warp and the fabric in a weaving machine;

Fig. 2

a schematic representation of the forces acting on the clamping member;

Fig. 3

a first embodiment of a device according to the invention;

Fig. 4

a second embodiment of a device according to the invention;

Fig. 5

a third embodiment of a device according to the invention and

Fig. 6

a fourth embodiment of a device according to the invention.

1 shows the course of the warp threads and the fabric in a weaving machine and the elements of the weaving machine interacting with them. A device 4 for tensioning the warp 2 runs from a warp thread 2 unwound by a warp thread 1 controlled by a warp let-off device (not shown) controlled by a warp beam 1 (not shown) A plurality of healds 5 and through a reed 6 to the binding point 7. After the binding point 7, a fabric 8 runs over a breast tree 9, a fabric take-off device 10 to a fabric tree 11, where the fabric 8 is wound up.

The device 4 in question contains a support tree 14 which is arranged in the weaving machine in a fixed or pivotable manner and a tensioning boom 15 which is connected to the support tree 14 and can be pivoted about an axis 16 about the stationary support tree or with the support tree. The spanning tree 15 is low in mass, i.e. tubular and supported in a plurality of bearings within the weaving width. Embodiments of the device 4 according to the invention are described with reference to FIGS. 3 to 6. The weaving machine is designed in such a way that the tensioning tree, in the position perpendicular to its pivot axis, assumes a basic position of 0 ° within the pivoting range and can be pivoted by +/- 25 ° with respect to this basic position, the sign + a pivoting movement in the warp direction and the sign - Indicates a pivoting movement against the warp direction.

In the method according to the invention, a partial swiveling area of the tensioning tree is determined based on the textile-technical data and the yarn-specific data within the swiveling range, which is required to maintain the tension of the warp. The absolute amount of this partial swivel range and its geometrical position within the swivel range mainly depends on the elasticity of the warp yarn, but in practice is in the range from 0 ° to 20 °, advantageously in the range from 0 ° to 15 °.

By dividing the swivel movement in the swivel range, a force profile can be determined for a force F _M directed in the warp direction, the change of which is kept within narrow limits. This force F _M is measured at one of the bearing points. A force transducer, which is aligned with the line of action of the force F _M , thus generates an essentially constant signal, which is included in the control. The swiveling range corresponding to the yarn properties can thus be determined within the swiveling movement of the tensioning tree in order to generate the required warp tension F _K in the warp.

Reference is made to FIG. 2, which shows a schematic representation of the assignment of the elements and forces relevant to the method according to the invention in two pivot positions within a partial pivot range.

From the geometric arrangement of the deflecting tree 3 and the tensioning tree 15 which can be pivoted about the axis 16, the course of the weaving chain results, which is shown in FIG. 2 as a line drawing, namely when the tensioning tree 15 assumes the basic position or a pivoted position.

As can be seen from FIG. 2, the resulting force F _R lies on the perpendicular line of the line and changes in size and direction. Because of these changes, the force F _{R is} unsuitable for a measurement. In the method according to the invention, a force F _M to be measured is determined on the basis of the geometric arrangement and the lines, the change in the direction of the connection R _ST between Supporting tree and spanning tree are constant and almost constant in size.

When determining F _M , it is assumed that the warp force F _{K is} constant. The value of F _R is therefore only dependent on the angle α.

.It follows: ${\text{F}}_{\text{R}}\text{= f (α)}$

.

The value of the angle β changes with the pivoting. This change is dependent on both the change of the angles α and ϕ.

.Therefore: $\text{β = f (α, ϕ)}$

.

Since the angle ϕ should remain constant over the partial swivel range, it follows $${\text{F}}_{\text{M}}{\text{= F}}_{\text{R}}\text{· Cos β.}$$

ergibt sich: $$\begin{array}{c}\begin{array}{c}{\text{F}}_{\text{R}}{\text{(α}}_{\text{1}}{\text{) · cos β (α}}_{\text{1}}{\text{, ϕ) = F}}_{\text{R}}{\text{(α}}_{\text{2}}{\text{) · cos β (α}}_{\text{2}}\text{, ϕ)}\\ \text{oder}\frac{{\text{F}}_{\text{R}}{\text{(α}}_{\text{1}}\text{)}}{{\text{F}}_{\text{R}}{\text{(α}}_{\text{2}}\text{)}}\text{=}\frac{{\text{cos β (α}}_{\text{2}}\text{, ϕ)}}{{\text{cos β (α}}_{\text{1}}\text{, ϕ)}}\end{array}\end{array}$$

Under the condition $${\text{F}}_{\text{M}}\text{= const.}$$

surrendered: $$\begin{array}{c}\begin{array}{c}{\text{F}}_{\text{R}}{\text{(α}}_{\text{1}}{\text{) · Cos β (<figure-callout id="1" label="α" filenames="imgf0001.png" state="{{state}}">α</figure-callout>}}_{\text{1}}{\text{, ϕ) = F}}_{\text{R}}{\text{(α}}_{\text{2nd}}{\text{) · Cos β (α}}_{\text{2nd}}\text{, ϕ)}\\ \text{or}\frac{{\text{F}}_{\text{R}}{\text{(α}}_{\text{1}}\text{)}}{{\text{F}}_{\text{R}}{\text{(α}}_{\text{2nd}}\text{)}}\text{=}\frac{{\text{cos β (α}}_{\text{2nd}}\text{, ϕ)}}{{\text{cos β (<figure-callout id="1" label="α" filenames="imgf0001.png" state="{{state}}">α</figure-callout>}}_{\text{1}}\text{, ϕ)}}\end{array}\end{array}$$

With this equation, the angle ϕ can be determined for a given swivel range.

Finally, the swivel range for the spanning boom is determined so that the basic position is within the partial swivel range. Thus, the warp tension can be determined largely correctly by measuring the force F _M regardless of the position of the tensioning boom and the measured value can be directly included in the control of the warp let-off.

3 shows a first embodiment of a device 4 according to the invention. The spanning tree 15 is mounted at its ends in a lever 21 which is arranged on the stationary supporting tree 14 and can be pivoted about the axis 16. A spring 22 is provided in order to produce the tensioning effect on the warp 2. The clamping tree 15 is provided with trunnions 23, which are each rotatably arranged in a bearing bush 24. A force transducer 25 is integrated in the bearing bush 24 such that the normal runs in the center of the pressure receiving surface and through the center of the bearing bush. The bearing bush 24 is arranged in the lever 21 so that the normal is congruent with the line of action of the force F _M. The bearing bush 24 can be fixed in the bore of the lever 21 by means of a set screw, pin or the like.

In the embodiment shown in FIG. 4, the spanning tree 15 is supported on a rolling basis. For this purpose, a bearing block 31 is provided. The bearing block 31 is arranged on a shaft 32 which is under spring action and can be pivoted about the axis 16. There are two rollers 33 with journals 34 which are mounted in the bearing block 31. A roller 33 is assigned a force transducer 35, which is arranged in the bearing block 31 and is connected to the bearing journal 34 in a force-transmitting manner, such that the normal in the center of the pressure receiving area is congruent with the line of action of the force F _M.

5 shows an embodiment of a device according to the invention, in which a support part 41 is pivotally arranged in the bearing block 31 instead of a roller. The support part 41 has trunnions 42 which are rotatably mounted in the bearing block 31 and a semicircular recess 43, the radius of which is adapted to the outer diameter of the clamping tree 15, so that the recess 43 is positively connected to the clamping tree. A force transducer 35 is arranged in the support part 41 in such a way that the normal of the pressure receiving area runs through the center line of the radius of the recess 43.

FIG. 6 shows an embodiment of the device according to the invention, in which the tensioning boom 15 is supported on a rolling basis. For this purpose, a support member 51 is attached to the shaft 32 and an arrangement 52 with two rollers 53 is provided, which is adjustably mounted on the support member 51. On the supporting part 51, a curved receiving part 54 for the arrangement 52 is fastened, the radius of curvature of which lies on the center line of the tensioning boom 15 supported on the rollers 53 of the arrangement 52. The arrangement 52 has a cage 55 in which the rollers 53 are rotatably mounted. The cage 55 is designed such that it lies positively on the receiving part 52. A roller 33 is assigned a force transducer 34 which is arranged in the cage 55 and is connected to the bearing journal of the roller in such a way that the normal of the pressure receiving surface runs through the axis of rotation of the roller 33.

The arrangement 52 is adjustably arranged on the receiving part 54 in order to adjust the normal of the pressure receiving surface to the force F _M to be measured, so that the normal of the pressure receiving surface and the line of action of the force F _{M are} congruent. A screw 56 is provided to fix the set position.

In the method, a force F _{M is} measured which, depending on the course of the warp 2 and on the geometric arrangement of the deflecting element 3, the tensioning element 15 and the pivot axis 16, has approximately the same size over the pivot range.

As a result, the warp tension can be largely correctly determined by measuring the force F _M regardless of the position of the tensioning element and the measured value can be directly incorporated into the control of the warp let-off.

Claims (13)

Method for measuring the tension of a warp in a weaving machine, wherein the warp is guided over a deflection element and a spring-symmetrical, rotationally symmetrical tensioning element, which is pivoted about an axis under the action of the warp and where a force acting on the tensioning element is caused by a Tension member force-transmitting connected force transducer is measured, characterized in that the force F _{M is} measured, which, depending on the course of the warp and on the geometric arrangement of the deflecting member, the tensioning member and the pivot axis over the pivot range substantially the same size. A method according to claim 1, characterized in that the force F _{M is} measured, the line of action of which includes an angle ϕ of less or greater than 90 ° with a plane connected to the center line of the tensioning element and the pivot axis, and that the force is measured during the to-and-fro movement becomes. Method according to one of claims 1 or 2, characterized in that the clamping member is pivoted in selectable partial pivoting ranges of, for example, 15 ° and that the line of action of the force F _M to be measured is determined for each partial pivoting range. Device for carrying out the method according to one of claims 1 to 3, with a deflecting member (3), a clamping member (15) which can be pivoted about an axis (16) and a force transducer (25, 35) which has a flexible pressure receiving surface and Has at least one measuring element which is connected to the pressure receiving surface, characterized in that the force transducer (25, 35) and the tensioning element (15) are arranged relative to one another such that the normal in the center of the pressure receiving surface and the line of action of the force F _M are directed essentially the same. Apparatus according to claim 4, characterized in that the force transducer (25, 35) and the tensioning member (15) are arranged in relation to one another such that the normal and the line of action are congruent. Device according to one of claims 4 or 5, characterized in that the clamping member (15) is supported in bearing points and that at least one bearing point is provided with a force transducer (25, 35). Device according to one of claims 4 to 6, characterized by a spring-acting member (21, 51) which can be pivoted about the axis (16) and an arrangement (24, 52) for receiving the tensioning member (15), the force transducer (25, 35) is integrated in the arrangement (24, 52) and the arrangement (24, 52) can be adjusted with respect to the link (21, 51) in the circumferential direction of the tensioning element (15) to the force transducer (25, 35) to align with the line of action of the metering force F _M. Apparatus according to claim 7, characterized by adjusting means to adjust the arrangement (24, 52) with respect to the line of action of the force F _M to be measured. Device according to one of claims 7 or 8, characterized in that the arrangement comprises a bearing bush (24) which is arranged in the link (21) and comprises a means for fixing the bearing bush (24) against rotation and that the force transducer (25) in the bearing bush (24) is integrated. Device according to one of claims 7 or 8, characterized in that the arrangement (52) consists of a cage (55) and two rollers (33) and that the force transducer (35) is connected to a roller (33) in a force-transmitting manner. Device according to one of claims 4 to 6, characterized by a bearing block (31) with two rollers (33) on which the tensioning element (15) is supported and that the force transducer (35) is connected to a roller (33) in a force-transmitting manner. Device according to one of claims 4 to 6, characterized by a bearing block (31) with a roller (33) and a support part (41) on which the tensioning element (15) is supported and that the force transducer (35) in the support part (41) is arranged. Weaving machine with a device according to one of claims 4 to 11, characterized in that the device is arranged downstream of a warp beam (1) in the weaving course.

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