CN106192170B

CN106192170B - Reed for air-jet loom

Info

Publication number: CN106192170B
Application number: CN201610620414.3A
Authority: CN
Inventors: F·拉波利尼; G·普雷维塔利; F·莫兰蒂; B·布里诺里
Original assignee: Itema SpA
Current assignee: Itema SpA
Priority date: 2015-05-26
Filing date: 2016-05-26
Publication date: 2020-05-05
Anticipated expiration: 2036-05-26
Also published as: ITUB20150706A1; EP3098338B1; JP6839932B2; HK1231528A1; JP2017020153A; TR201810261T4; EP3098338A2; CN106192170A; EP3098338A3

Abstract

A reed for an air jet loom, comprising a plurality of side-by-side dents, each dent having a wide central recess (C) separating the upper and lower parts of the dent to form the launch channel of the reed, said central recess (C) being defined at least by a lower wall (L2), a bottom wall (L3) and an upper wall (L4), two inner curved connecting surfaces (R2, R3) connecting said walls to each other, an outer curved connecting surface (R1) connecting said lower wall (L2) with said dent lower outer wall (L1), said outer curved connecting surface (R1) having one end tangent to said lower wall (L2) and the other end forming an angle with said dent lower outer wall (L1) different from 0 °.

Description

Reed for air-jet loom

Technical Field

The present invention relates to a reed for an air jet loom, and more particularly to a reed capable of reducing the amount of compressed air required to pass a weft yarn through a shed.

Background

It is known that in air-jet weaving machines the weft thread is inserted into the shed without the aid of mechanical elements, and is transported along the shed only by means of a jet of air, usually compressed air. The generation of the air jets comprises a main nozzle system, usually placed on the left side of the machine, which provides the weft yarn with an initial acceleration, and a secondary nozzle system, which is uniformly arranged along the shed, which is required to maintain a suitable speed of the weft yarn as it passes through the length of the shed.

It is also known that, in order to provide a rapid weft-conveying air flow, i.e. an air flow that is geometrically well-defined and sufficiently concentrated, the launch channel is formed inside the reed by providing a suitably shaped recess in the enlarged central area of the single reed dent defined by the upper and lower circular portions or "noses" of the reed dent; the side-by-side recesses of the plurality of parallel dents forming the reed thus define a launching channel in which the weft yarn moves.

As described above, the specific shape of the central recess of the single dents is the same as the sectional shape of the shooting channel, which seriously affects the manner of weft yarn conveyance and the amount of compressed air consumption required for correctly conveying the weft yarn.

In fact, the emission channels formed in the reed are channels that are "open" outwards, all coinciding with the gaps between the individual dents and eventually towards the fabric being woven, so that a significant part of the compressed air flow used to convey the weft yarn is dispersed through or in front of the reed, without being used to convey the weft yarn, thus reducing the efficiency of the use of compressed air.

According to one main feature of the patent (figure 1), the dimensions of the connecting radius (R) of the upper inner corner of the U-shaped recess, which is the area where the weft yarn moves along the launch channel, are smaller than the connecting radius (R) of the opposite lower corner of the U-shaped recess, which is the area where the weft yarn moves along the launch channel, and the absolute value of this connecting radius is small, less than 1mm, preferably less than 0.5mm.

A second important feature of the reed is that the jargon of the textile field is simply defined as a "nose" and does not have a symmetrical structure, according to the projecting part of each dent defining the upper and lower U-shaped recesses; in a first embodiment of the reed (FIG. 1), the width W3 of the lower nose is about 75% of the width W1 of the upper nose, both measured from the bottom wall 342 of the central U-shaped recess.A width W13 of the lower nose is even reduced to about 25% to 55% of the width W11 of the upper nose in another embodiment (FIG. 2); both widths are also measured from the bottom wall 842 of the central U-shaped recess in this embodiment.

A third feature of the present patent is that, in order to divert the air jet inside the weft yarn launching channel, the walls defining the U-shaped recess have a moderate inclination of about 10 ° in the direction of weft yarn progression transverse to the reed dent plane, thus reducing the leakage of compressed air passing through each reed dent of the reed at each reed dent.

EP 245520 (toyota) subsequently discloses again the same second embodiment of the cited toyota patent, wherein however some dimensional limitations are specified (fig. 3), which will be discussed in more detail, determining a preferred configuration of the lower wall of the U-shaped recess of the dent.

Disclosure of Invention

Under the structure of the prior art, considering that the cost of compressed air is the main production cost of an air jet loom factory at present, in order to further reduce the consumption of the compressed air, the inventor solves the problem of further optimizing the shape of the central U-shaped concave part of the reed dent of the air jet loom without damaging the weft yarn conveying efficiency.

The solution of this problem and the achievement of the above-mentioned object is achieved by means of a reed for an air jet weaving machine, the U-shaped central recess shape of the dents of which is defined by the features of claim 1 other preferred features of the reed according to the invention are defined by the dependent claims.

Drawings

Further characteristics and advantages of the reed for an air-jet loom according to the invention will become clearer in the following detailed description of a preferred embodiment, which is given by way of non-limiting example only, as illustrated in the accompanying drawings, wherein:

figure 1 is a front view of the central part of a dent of a known type according to a first embodiment of patent EP0691430 (toyota).

Figure 2 is a front view of the central part of a dent of a known type according to a second embodiment of patent EP0691430 (toyota).

Figure 3 is a front view of the central part of a dent of a known type disclosing a special embodiment of the dent of figure 2 in EP 245520 (toyota).

Fig. 4 is an enlarged view of the center portion of the dents according to the present invention.

Figure 5 is a further enlarged detail view showing in detail the dents of figure 4.

Detailed Description

The inventor has started from the state of the art already presented in the background of the invention section of this specification, i.e. the consumption of compressed air for transporting a weft thread in a reed passage decreases with decreasing distance of the weft thread from the secondary nozzle, especially the closest prior art to the invention as shown in fig. 3, said distance being the distance between the blowing point 18 of the secondary nozzle 17 and the bottom wall 22 of the U-shaped central recess of the dent, in fact, the weft thread moves along a launch passage close to said bottom wall 22, more precisely along the upper end of said bottom wall 22.

At the same time, the blowing point 18 must be kept outside the U-shaped central recess at a certain minimum distance from the reed, so that the secondary nozzle 17 does not cause defects in the weft or warp threads.

In order to reduce the distance between the blowing point 18 of the secondary nozzle and the bottom wall 22 of the U-shaped central recess, the transverse dimension of the lower nose 20 of the dent is greatly reduced according to the known preferred solution, in other words, the extension length B of the lower nose 20 with respect to the bottom wall 22 of the U-shaped central recess is considerably lower than the corresponding extension length a of the upper nose 19 beyond the dent.

According to the prior art disclosed in patent EP 245520, shown in figure 3, the shape of the wall 23 of the dent, i.e. the lower wall of the U-shaped central recess, must be such that the sum of the radii CR and DR of the curved connecting

surfaces

25 and 29 is defined to be less than the distance B, preferably greater than 1.5mm, so that, according to this definition, the lower wall 23 of the dent is formed with a flat portion α located between the curved connecting

surfaces

25 and 29, the presence of which, as described in the above-cited patent, effectively prevents the air flow from the secondary nozzle from diffusing outside the firing channel and thus stabilizes the weft yarn along the desired path position, substantially reducing the number of false wefts.

However, the inventors have carried out studies on reeds for air-jet looms starting from the state of the art and have found that the above-mentioned solution, although providing satisfactory performance, does not improve further, in fact, in order to further reduce the distance B by further reducing the air flow delivered to the secondary nozzle 17, it is noted that the effect of weft stabilization by the flat portion α of the lower surface 23 of the launch channel soon becomes insufficient, in this case, it is further assumed that the dispersion effect caused by the curved surface 29 of radius DR is dominant.

To overcome this limitation, the inventors assume that a lower wall of a center recess of a reed dent having a completely different shape is provided, abandoning the conventional shape in which an arc-shaped connecting surface is tangent to a straight portion of the wall to define a center recess that has been provided so far, and propose a curved profile having one end tangent to the flat portion α and the other end forming a corner of an outer wall of the reed dent instead of an outer arc-shaped connecting surface of a lower nose of the reed dent (i.e., a portion indicated by reference numeral 29 shown in prior art fig. 3).

Figure 4 shows a new dent construction according to the invention comprising lower and upper inner arched connecting surfaces R2 and R3, respectively, the shape of which is known, i.e. they are tangent to one end of the flat wall adjacent to the dent central recess C, connecting to the flat wall. In particular, the lower arcuate connecting surface R2 is tangent to the lower wall L2 and the bottom wall L3, while the upper arcuate connecting surface R3 is tangent to the lower wall L3 and the upper wall L4 preferably the arcuate connecting surfaces R2 and R3 are circular arcs whose respective radii R2 and R3 are of lesser magnitude, for example greater than or equal to 1 mm; preferably, the radius R3 of the upper curved connecting surface R3, which substantially defines the weft yarn path region, is slightly larger than the radius R2 of the lower curved connecting surface R2.

As expected above, the curved connecting surface R1, which connects the lower wall L2 of the central recess C of the reed dent with the lower outer wall L1 of the same reed dent, also has a circular arc-shaped profile, but its radius R1 is obviously greater than the radius R2 and r3. defined above, and in fact the value of the radius R1 of the curved connecting surface R1 is so high that the following relation is always satisfied:

r1+r2＞B

in addition, the radius r1 of the curved connecting surface is only tangent to the inner wall L2 of the dent central recess C and not to the dent outer wall L1, forming an angle different from 0 DEG and thus forming an edge with respect to the outer wall L1.

Finally, as is clearly shown in the accompanying drawing (figure 5), the lower wall L2 of the dent central recess C is offset from the upper wall L4 opposite thereto, in order to facilitate the entry of the air flow coming from the secondary nozzle into the firing channel to improve the delivery of the weft thread according to the prior art teachings in geometry, however, in the embodiment shown, the two offset walls L2 and L4 are formed, with the two offset walls L2 and L4 having a slightly greater angle, in particular an angle of 12 ° to 14 °, compared to the prior art, with the best results obtained according to the air consumption rate for the weft thread delivery.

First, the curvature of the curved connecting surface R1 is small due to the large radius value R1 of this surface, so that the first section tangent to the straight lower wall L2 actually has the same effect on the weft yarn stability in the firing channel as the extended straight lower wall L2, so that the weft yarn stability is greatly improved, the critical value for the length of the straight lower wall 86l 25 indicated in the prior art no longer exists as long as the value of the radius R1 is sufficiently large, and the length of said lower wall L2 can also be below said critical value without actually adversely affecting the weft yarn stability.

By choosing the radius value R1 of the larger curved connecting surface R1, the straight lower wall L2 can be completely eliminated and then the curved connecting surface R1 can be directly connected with the curved connecting surface R2. The tangents of these curved surfaces at their intersection points (in this case the inflection points) of course preferably satisfy the inclination condition with respect to the upper wall L4, which has been defined previously with respect to the straight lower wall L2.

The second desired advantage of this shape is the reduction of the width B of the bottom projection of the reed dent relative to the bottom wall L3 of the central recess C as is clear from figure 5, the value of the width B of the reed dent of the present invention is actually much smaller on an enlarged scale compared to the width B 'of the reed dent obtained by extending the arc-shaped connecting surface R1 through a larger arc until intersecting the outer lower wall L1' of the reed dent.

Finally, a third advantage of the reed dent shape of the present invention is to reduce the width of the reed dent central recess C opening from the width K 'to the width K (fig. 5), which is just the width of the reed dent opening obtained by the arc-shaped connecting surface R1 covering a larger arc until it intersects (intersects by tangency, shown by the dashed line) with the outer lower wall L1' of the reed dent.

It should be understood that the reduction of the width of the opening of the dent central recess C from K' to K can also be achieved by eliminating the end portion of the curved connecting surface R1, i.e. showing an almost vertical slope, on the one hand, the reduction of the width of the opening of the dent central recess C in correspondence with the opening of the launch channel does not therefore cause a significant reduction of the input air flow in said launch channel, on the other hand, it reduces the interference of the lower nose of the dent with the weft during the shed opening and closing step, thus reducing possible defects of the fabric.

It is to be understood, however, that the invention is not limited to the precise arrangements disclosed, which are merely exemplary of embodiments of the invention, and that various other modifications may occur to those skilled in the art without departing from the scope of the invention, as defined solely by the appended claims.

Claims

1. Reed for an air jet weaving machine, comprising a plurality of side by side reed dents, each reed dent having a wide central recess (C) separating the upper and lower parts of the reed dent to form the launch channel of the reed, said central recess (C) being defined at least by a lower wall (L2), a bottom wall (L3), an upper wall (L4), two curved inner arc-shaped connecting surfaces (R2, R3) connecting the lower wall, bottom wall and upper wall to each other and an outer arc-shaped connecting surface (R1) connecting the lower wall (L2) with the outer wall (L1) of the lower part of the reed dent, characterized in that one end of the outer arc-shaped connecting surface (R1) is tangent to the lower wall (L2) and the other end of the outer arc-shaped connecting surface forms an angle different from 0 ° with the outer wall (L1) of the lower part of the reed dent.

2. Reed for air-jet looms according to claim 1, characterised in that the outer arched connecting surface (R1) and the inner arched connecting surface (R2) of the lower wall (L2) defining the central recess (C) are arcs of a circle with radius R1 and R2, respectively, whose radii satisfy the following relation:

r1+r2>B

wherein B is a width of a lower portion of the dent protruding laterally with respect to a bottom wall (L3) of the central recess (C), coinciding with a wider portion (nose) of the lower portion of the dent.

3. Reed for air-jet looms according to claim 2, characterized in that the lower wall (L2) and the upper wall (L4) of the central recess (C) of the dent diverge from each other towards the opening of the central recess (C) by an angle of 12 ° to 14 °.

4. Reed for air-jet looms according to claim 2, characterised in that the inner arched connecting surfaces (R2, R3) defining the bottom wall (L3) of the central recess (C) are arcs of a circle with radius R2 and R3, respectively, whose radii satisfy the following relation:

r2≤r3。

5. reed for air-jet weaving looms according to claim 4, characterized in that the values of the radii r2 and r3 are equal to or greater than 1 mm.