Open weft picking channel

Technical field

The invention relates to an open weft picking channel made by profile dents of a beat-up reed of a pneumatic weaving machine with built-in auxiliary jets whose outlet apertures reach into the width of the weft picking channel and in which at least a part of the weft picking channel has a constant profile.

Background of the Invention

In pneumatic weaving machines, the weft is inserted into the shed of warp threads by means of a main jet situated on its entry side. In the shed, the weft is led through a picking channel consisting either of orifices or of profile dents of a beat-up reed. In modern high-speed weaving machines, auxiliary jets acting on the face of the weft in process of picking are arranged along the length of the weft picking channel. The profile dents of the beat-up reed are fitted with a pair of protrusions creating a bounded weft picking channel open in the direction of the fabric being produced.

An open weft picking channel consisting of profile dents of a beat-up reed has been disclosed for instance in the CS patent Nr. 219 281 showing several shape modifications of the dents. The protrusions of the profile dents of the beat-up reed create here an open weft picking channel shaped substantially as a lying U. In the area of the projection of the auxiliary jets, the profile dents thus shaped are replaced by dents of a different shape with the upper protrusion only.

and the weft picking channel is in this section bounded only by two sides, i. e., by the upper side and by the back beat-up side. In a variant, they are replaced by only flat beat-up dents.

In another variant, the profile reed with an open weft picking channel has in the area of the projection of the auxiliary jets situated alternately flat dents and dents fitted with the upper protrusion. Consequently, the cross section of such weft picking channel is constant, with the lower side or possibly also the upper side, consisting of reed dents, being omitted only in the area of the auxiliary jets.

The drawback of this solution consists in the relatively long distance between the auxiliary jets and the weft picking channel involving low efficiency of the picking system and due to this also an increased consumption of the picking medium.

The patent DE No. 3,740,666 has disclosed a solution in which a short section of the entry side of the weft picking channel is conicaily narrowing and is followed by a parallel-shaped section throughout the whole (remaining) length of the weft picking channel. This modification of the profile dents is adapted to the main picking machanism consisting of two main jets situated over each other and permitting the weft mixing or the colour change. Due to the variability of the entry axis of the picking weft, the entry side of the weft picking channel is extended so as to form a funnel for drawing in the wefts into the parallel operating section.

Such solution relates only to the design of the main jets improving the entry of the picking medium into the weft picking channel; here, as well, the distance between the auxiliary jets and the weft picing channel is considerably long, and the solution is thus afflicted with drawbacks similar to those of the

previous ones.

A still another solution of the weft picking channel of a pneumatic weaving machine has been disclosed in the CS AO No. 219 512. The upper and the back wall of the weft picking channel consist of profile dents with upper nose-shaped protrusions. The lower part of the weft picking channel wall consists of an auxiliary body with auxiliary jets, and the back surface of the auxiliary body carries warp threads of the lower shed strand. Said back surface is saw-like shaped, and the mouths of the auxiliary jets are situated in the front faces of the saw-like protrusions. The upper side of the weft picking channel, consisting of the protrusions of the reed dents, is parallel to the direction of the pick weft.

In variants, the upper side of the body comprising the auxiliary jets can have various shapes in the sections of the saw-like protrusions.

This solution is confronted with some problems from the point of view of the air streaming through the weft picking channel whose lower side is full while the other sides consist alternately of dents and of gaps between them.

In the embodiment described in the CS AOn No. 210 296, said body with auxiliary jets is by means of an excentric mechanism arranged adjustably with respect to the protrusions of the reed dents so as to partly close the weft picking channel at the pick moment.

The drawback of this solution consists in the switching over of the lower shed which increases the risk, in particular in the selvedge sections, of the warp thread of the upper shed getting caught into the picking recess of the glider. Besides, the yarn remains in the weft picking channel and thus unfavourably

effects the picking medium, especially with thick yarns. In the weft picking channel, the yarn is explosed not only to the effect of air pressure but also to increased abrasive wear on the channel bottom

In still another known embodiment, described in the CS patent No. 198 232, a better beat-up of the weft into the binding point of the fabric in process of manufacture is aimed at by the reed being arranged in such a manner that the dents and the protrusions out of which the weft picking channel is made have in the temple area flat dents and then the profile ones, or the profile dents regularly alternating with the flat ones independently of the position of the auxiliary jets.

This solution requires a design modification of a sliding inserting jet and of a suction jet that is difficult to realize in case of the colour change. The auxiliary jets are situated at a long distance from the weft picking channel with the ensuing low efficiency of the pick system and increased picking medium consumption.

The last known embodiment, disclosed in the US patent No. 5,323,814, has in the area of the weft picking channel the sides slanted in such a manner as to direct the air stream towards the centre of the weft passage. The slanting is carried out in at least a part of the thickness of each dent, while the shape of the weft picking channel remains constant and paralel with the picked weft.

The drawback of this solution, common also to most of the preceding ones, consists in the considerably long distance between the auxiliary jets and the weft picking channel reducing the efficiency of the pick system acting on the front of the weft being picked, involving the risk for the weft being incorrectly picked through the whole length of the weft picking channel, and increasing the consumption of the picking medium.

Disclosure of the invention

Said drawbacks are to a large extend eliminated by the open weft picking channel of varying cross section according to the invention whose principle consists in that the outlet apertures of the picking medium of rod-like jets are situated under the lower outline of the constant profile of the weft picking channel

The advantage of the embodiment of the open weft picking channel according to the invention consists in the possibility substantially to increase the dynamic pressure of the picking medium at the expected motion path of the weft without increasing the picking medium pressure in the auxiliary jets.

Preferably, at all times, more than one dent following in the direction of the weft pick after the auxiliary jet has the lower outline of the weft picking channel below the level of the outlet aperture of the auxiliary jet, thus ensuring a better air stream passage into the operating section of the weftpicking channel and improving the air streaming in the operating section of the weft picking channel while the weft is carried by the shed.

The lower outline of the weft picking channel of the profile dents after the auxiliary jet is narrowing in the direction of the weft pick in the direction towards the constant profile of the weft picking channel, thus still more improving the air streaming coming from the auxiliary jets and passing through the weft picking channel.

Preferably, in the section of the narroving profile of the weft picking channel according to the previous embodiment, the lower edges of the profile

dents are slanted into one slanting plane converging in the direction of the constant profile. This slanting of the lower edges provides for undisturbed streaming of the picking medium through the weft picking channel.

For reliable weft insertion into the shed, the constant profile dents occupy in each case at least one third of the distance between two auxiliary jets

The advantage of the open weft picking channel according to the invention consists in the reduced consumption of the picking medium as well as in increased reliability and speed of the weaving process. Directing the auxiliary jets more into the direction of the weft pick, defined by the shape of the weft picking channel and the positioning of the auxiliary jets, also increases the uniformity of the picking medium streaming. Another effect consists in the reduction of the batten weight and, consequently, of its inertia forces.

Brief descriptions of the drawings

The object of the invention is shown in the accompanying drawings in which Figs. 1 and 2 show in cross section two embodiments of a beat-up reed with various fixing in the batten of a weaving machine, with alternately attached auxiliary jets. Fig. 3 is a front view of the beat-up reed with an open weft picking channel according to the invention, and Fig. 4, 5, 6 and 7 show profile dents with various profile creating a proportionally variable weft picking channel.

Examples of Embodiment out the Invention

A beat-up reed 1 with profile dents 2 is by means of a wedge 3 fixed in a wedge-shaped groove 4 of a batten 5. Adjustably fixed to the batten 5 from the

side of the fabric 6 being produced are bodies 7 having adjustably fixed thereon auxiliary jets 8. Inserted between the dents 2 are warp threads ? passing through the guide eyes of healds 10.

In the embodiment shown in Fig. 2, the lower frame of the reed is a shaped one. Through the holes in its side wall there are inserted and with a screw 11 fastened the cylindrical bodies 7 with the auxiliary jets 8. The profile dents 2 are equipped with a protrusion 1_2 with a recess creating the profile of a weft picking channel 13. In the beat-up reed 1 according to the invention, the size of the recesses of the profile dents 2 changes from one profile dent to the other. thus modifying the resulting outline of the weft picking channel 13 along the length of the beat-up reed 1. By the recess depth of each dent 2 is defined the width of the weft picking channel which is constant throughout, while the back walls of the recess, forming the beat-up edge of the reed 1, lie in the same plane. The upper edge of the recess of each dent 2 lies in the reed 1 in the same height. The lower edges of the dents 2 creating the lower outline of the weft picking channel 13 lie in front of each auxiliary jet 8 in the same height and form in cooperation with the back and the upper edge the constant profile of the weft picking channel 13. The length of this constant profile of the weft picking channel 13 between two adjacent auxiliary jets 8 makes at least one third of the distance between the adjacent auxiliary jets 8. At the place of insertion of the auxiliary jet 8, the first dents 21 have no lower outline edge, the back beat-up edge being continuous up to the lower edge of the first dent 21 This provides for a room in the reed 1 to situate the auxiliary jet 8 into the width of the weft picking channel 13. The whole outline of the auxiliary jets 8 lies under the lower outline of the constant profile of the welt picking channel 13.

Behind the auxiliary jet 8 in the direction of the pick of a weft 16, the lower

edge of the second profile dent 22 forms the outline of the weft picking channel 13 below the level of an outlet aperture 14 of the auxiliary jet 8. Each following third dent 23 has its lower edge positioned somewhat higher until, after a length, these lower edges reach the lower outline of the weft picking channel 3 formed by the fourth dents 24 with a constant profile. The lower edges of the third dents 23 can be slanted in a slanting plane converging from the second profile dent 22 towards the constant profile of the weft picking channel 13.

Due to the fact that the upper edges of all dents 2 lie in a plane while the lower edges of the dents 2 after the auxiliary jet 8 lie higher and higher, they form the lower outline of the weft picking channel 13 narrowing in the direction of (towards) its constant profile. By means of pressure hoses 15, the auxiliary jets 8 are attached to a not represented source of pressure medium.

During the weaving process, the weft 16 is inserted by a not represented main pick jet into the weft picking channel 13 whose varying cross section is made by the profile dents 21, 22, 23, and 24. After its insertion into the weft picking channel 1_3, they create a stream of the picking medium of the timed auxiliary jet 8 acting in particular on the front of the weft 16 being inserted, and lead it in the upper inner corner of the weft picking channel 13.

The batten 5 swinging in a not represented weaving machine carries both the reed 1 and the auxiliary jets 8. The insertion of the weft 16 through the weft picking channel 13 takes place at a period when the healds 10 of a not represented harness mechanism shape the warp threads 9 into an open shed 17. Due to the fact that the outlet apertures of the auxiliary jets 14 are arranged in the width of the weft picking channel 13, the arrangement of the profile dents 2J . 22, 23, and 24 permits to direct the picking medium streams from these outlet

apertures __A under the upper outline edge of the weft picking channel 13 The fact that the lower edge of the weft picking channel 13 lies in a slanting plane directed towards the constant profile of the weft picking channel 1_3 made by the fourth profile dents 24, concentrates the picking medium, and its dynamic effect is better exploited. The weft 16 is thus pulled by a constant force regardless of its increasing distance from the auxiliary jet 8. The insertion of the weft 16 is uniform, and microloops due to the not uniform action of the picking medium along the length of the weft picking channel 13 are avoided. At the same time, the weft 16 in process of insertion is moved by the swinging motion of the batten 5 towards a binding point 18 representing the front of the fabric being produced. After the whole length of the weft 16 has been inserted, the back beat-up edge of the profile reed 1 beats the weft 16 into the binding point 18 whereupon it is covered by the warp threads 9 led in the eyes of the healds 10 fixed in not represented heald shafts. The dent 21 having assigned thereto auxiliary jets 8 in the profile reed 1, provide then for sufficient space for moving the warp thread 9 introduced between them during the changing of the shed 17.