FR2480317A1 - DEVICE FOR LAUNCHING THE FRAME FOR AN AIR JET WORKING MACHINE - Google Patents

Abstract

THE INVENTION RELATES TO A WEFT LAUNCHING DEVICE FOR AN AIRJET Loom. ACCORDING TO THE INVENTION, IT INCLUDES AIR GUIDING ORGANS 3 THROUGH RESPECTIVE OPENINGS AND AIR GUIDING RIGHTS 4 WHICH CONSTITUTE A THROAT 4A FOR GUIDING THE AIR THROUGH OR IS THROWN A WEFT WIRE FROM FROM AN INSERTION TUBING, EACH AIR GUIDING ORGAN HAVING A SLOT5 THROUGH WHERE THE WEFT WIRE EXIT FROM THE OPENING, AND BEING SPACED FROM ADJACENT PARTS SO AS TO CANCEL FRACTIONS OF LEAKING AIR CURRENT THROUGH THE SLOTS OF THE AIR GUIDING MEMBERS BY MEANS OF THE FRACTIONS OF THE AIR CURRENT LEAKING THROUGH THE SPACES BETWEEN THESE ORGANS, THUS OBTAINING A SAVING OF PRESSURIZED AIR BY PREVENTING THE WEFT WIRE FROM FLYING AND COMING OUT OF THE GUIDANCE THROAT DURING LAUNCHING OF THE WEFT. THE INVENTION APPLIES IN PARTICULAR TO THE TEXTILE INDUSTRY.

Description

i

  The present invention relates to an improvement

  to a device for launching the frame for a trade

  weaving machine, of the type having a main tubing

  or inserting the weft and a number of auxiliary tubing o the launch of the weft is accomplished by driving the weft yarn from the weft insertion tubing, mainly under

  the influence of the air jets of the auxiliary tubes.

  In connection with the launch in the weft in air jet looms, it is well known that there are typically two kinds of weft launching devices as will be described hereinafter. One (hereinafter referred to as "the first traditional device for launching the weft") is as follows: a jet of air ejected from a main pipe is converged towards the axis of a guide groove of the frame defined by a number of tapered air guide openings of placed bodies

  in a succession of air guides, which are aligned

  Closely in the direction of insertion of the weft, thus a stream of air formed in the guide groove of the weft is introduced to one side of the loom opposite the main pipe. A weft yarn injected by the main manifold at the same time as the air jet is driven by the stream of air thus formed to accomplish the launch of the weft. In these cases, the air stream formed in the guide channel of the weft

  can be favored by the air effect of a tubular auxiliai

  re placed between two adjacent air guiding members which are placed near the side of the trade opposite to the

  main tubing, if necessary.

  Another (hereinafter referred to as "the second traditional weft launching device") is as follows: a number of U-shaped air guide members are aligned relatively spaced along the direction of the launch of the the weft in order to close the three channels of a guide groove of the weft, and moreover a certain number of auxiliary tubes are placed at appropriate intervals along the guide groove of the frame to eject, angularly, jets air flow to the inner surfaces of the U-shaped air guiding members, the main-tube air jet serving merely to inject or push the weft yarn outwardly into the guide groove of the b weft, while the air jets of the auxiliary tubes serve to drive the weft yarn thus injected into the entire guiding groove of the weft. In this device, when the weft yarn injected by the main pipe reaches the proximity of an auxiliary pipe which is closest to the main pipe, the auxiliary pipe ejects a jet of air to blow the weft yarn in the distance, towards the side of the loom which is opposite to the main pipe, and such air jet itself comes out of the guide groove of the frame by the alignment games in the air guiding members, so the weft yarn is entralné

  a predetermined distance along the banks of the sur-

  internal faces of the U-shaped air guiding members. Such action is in turn transmitted to the tubing

  next auxiliary to complete the launch of the frame.

  As is apparent from the above, with the first conventional weft launching device, as the guide groove of the weft is formed by the radially nearly closed air guide openings of the guide members of the weft guide. air that are placed in succession, the air jet of the main manifold can be used to drive the weft yarn to the side of the loom opposite the main manifold. However, the air flow caused by the air jet at the outlet of the main pipe is subjected in succession to convergent actions due to the tapered guide openings

  of air, there is thus accumulation of resistance to

  due to the convergence of the air flow. Moreover, we do not

  can avoid air leakage through the alignment games.

  air guiding members. As a result, the rate of flow of the air stream gradually decreases in the guide groove of the weft and therefore, the first traditional weft launching device is not considered suitable for weaving.

of a wide fabric.

  With the second traditional device for launching the weft, it is possible to obtain a saving of the quantity of air in the main pipe. In addition, the weft entraining action is due to a number of auxiliary tubings and therefore this second traditional weft launching device is suitable for weaving a wide fabric. However, the air stream for driving the weft yarn is formed along the bottom of the inner surface of each U-shaped guide member, where the flow velocity of the air stream decreases rapidly undergoing resistance. to the flow of the lower inner surface section of the air guiding member. As a result, the total rate of flow of the air stream in the guide groove of the weft is lowered and consequently the

  direction of advance of the weft thread becomes unstable, provocative

  as well as a bad launch of the frame for example, because it can be taken in the game between the

  guiding members. In addition, the air jets of the tubu-

  auxiliaries inevitably come out of the throat of

  guiding the weft while retaining significant energy

  aunt as described above, and moreover the air reflected on the inner surface of the U guide members diffuses or dissipates, this air can not be used to drive the weft yarn. Consequently, he

  it is necessary to increase the number of tubing

  res to compensate the air in an amount corresponding to the air dissipated above, which necessarily increases the

amount of compressed air required.

  In view of the foregoing, it has already been proposed to solve the problems encountered in the second traditional device for launching the above weft by replacing its air guiding members with the air guiding members used in the process. first traditional above mentioned device launching the weft

  on the basis of the idea that the action of

  Weft threads are mainly accomplished under the influence of the air jets of the auxiliary tubing as disclosed in U.S. Patent Application No. 149,083 entitled "Weft Picking Device of Air Jet".

Type Weaving Loom "-.

  A device for launching the weft of an air jet loom according to the invention comprises a certain number of air guiding members aligned in the direction of the launching of the weft. The air guiding members are formed of respective and straight air guiding apertures without any conicity, these air guiding apertures constituting a guiding groove of the frame by o a weft yarn originating from a tubing insertion of the frame is launched. Each air guide member has a slot where the weft yarn exits the air guide opening. Each air guiding member is spaced from adjacent members to cancel leakage of the airflow fraction through the slot of the air guiding member by leakage of a fraction of the air stream. air through the spaces between the air guiding members so that the weft yarn is prevented from leaking out of the guide groove of the weft through the slot

of the air guiding member.

  With this arrangement, it becomes possible to significantly reduce the diameter of the air guide opening of each guide member to obtain greater air savings, by pocketing the weft thread voleter and s fly away from the guide groove of the

  frame during the launch of it.

  The invention will be better understood and other purposes, features, details and advantages thereof

  will appear more clearly during the description

  following explanatory diagram with reference to the accompanying schematic drawings given solely by way of example illustrating an embodiment of the invention and in which: - Figure 1 is a front elevational view of a preferred embodiment of a device for launching the weft of an air jet loom according to the invention; - Figure 2 is a cross-sectional view

  enlarged in the direction of the arrows, substantially

  line II-II of Figure 1; FIG. 3 is a cross-sectional view of the essential part of the device & launch of the frame of FIG. 1, illustrating a state of launch of the frame; and FIG. 4 is an illustration showing an experimental result obtained by one of the various experiments that have been performed in the permited process.

  to lead to the present invention.

  To facilitate the understanding of the present invention

  First of all, the results of experiments made by the inventors will be referred to in order to reduce the amount of air required to launch the frame on the basis of the weft launching device disclosed in the patent application. US Pat. No. 149,083. The experiments described hereinafter show the reduced diameter effect of the air guide openings of the air guiding members. The experiments were carried out so that a weft thread is injected through a main pipe into a guide groove of the weft defined by the air guide opening of each air guide member, ci being aligned in succession along the direction of the insertion of the weft, by decreasing the average diameter Dl of the tapered opening A for guiding the air (Tp: taper) of each air guiding member of Figure 4, at 18 mm, 16 mm and 14 mm in the experimental coniions which follow taper (Tp) (with respect to the axis of the guide groove of the weft on the cross-section containing the axis) : 70, thickness of the air guiding element: 2.9 mm distance between air guiding elements: 0.8 mm, auxiliary tubing: opening diameter of the tubing, '1.0 mm, no alignment 10 cm; and direction of air ejection: 120 (compared to

  the axis of the guide groove of the frame).

  In the experiments mentioned above, good launches of the weft were made even with the variation of the average diameter of the air guide opening of each guide member. However, other experiments have revealed that if the average diameter D 'is decreased to 12 mm, there is a slight displacement of the moving weft yarn so that it can be taken up by a slot B, and if the the average diameter D 'is further decreased to 10 mm, its driving end can exit through the slot B, which makes it impossible to launch the frame. Line L of FIG. 4 indicates the location of the leading end of the weft yarn, drawn by observing from the ctté of the loom opposed to the main manifold when there is

fluttering of the weft thread.

  By studying the aforementioned volumetric arrangement of the leading end of the weft yarn, the effect of the taper (Tp) formed on the surface of the air guide opening of the guide member is considered as being the cause of this volettement of the leading end of the weft thread. As the conicities (T 1) are inherently formed to converge, in succession, the flow of air passing through the openings A aligned in succession for guiding the air, it can of course be considered that the current of air passes through the entire air guide groove, repeating its contraction and expansion. It will be understood that if the diameter D 'of the air guide opening decreases, the cross-sectional area of this opening decreases sharply according to the square of the decreased amount & of the diameter D'. As a result, it can be seen that for a diameter of the air guide opening of 12 mm in the above experiments, the effect of repeated contraction and expansion of the air flow extends to the entire extent of the guiding groove of the frame, thereby causing the free end or leading end of the weft thread to move in displacement in this guiding groove. As a comparison with the experimental results above, other experiments were then carried out under the experimental conditions mentioned above, except that a straight air guide opening was used without taper (Tp), instead of

  the tapered aperture A for guiding the air, which opens

  The right angle of each air guiding member is defined by a generally circular inner surface which is perpendicular to a plane parallel to each air guiding member as indicated by reference numeral 4 on FIG. revealed that if the average diameter of the air guide opening in the above-described values of more than 12 mm, there is a sharp decrease in the weft of the weft yarn; if the same diameter is 12 mm, the action of the weft thread is

  good enough if the same diameter is 10 mm, the

  is lying. the frame is possible while the end

  The nante of the weft thread seems to fly out of the guide groove of the weft; and if this same diameter is 7 mm, the driving end of the weft yarn is flying out of the guide groove of the weft, the launch of the weft becoming

then impossible.

  Further consideration of this phenomenon of the outwardly flying quill wire revealed the following facts: although the diameter of the air guide opening of each guide member can be freely decreased, the width E As a result, the cross-sectional area ratio between the slot B and the air guide opening A increases sharply with the decrease in the width of the slot B. diameter of the opening A of each air guide. This increases the ratio of the fraction of the air flow exiting the air guiding aperture through slot B, so that the leading end of the detrame wire flies out of the guide groove through slot B under the influence of the fraction of the above air stream that has passed through slot B. In addition, it is assumed that the relative increase of the above fraction of the outgoing air stream is greater than that of the fraction of the air stream coming out of the alignment clearance of the air guiding members due to the omission of the conicity (Tp) of the guiding opening

of the air of each organ.

  The foregoing has led to the idea that, in order to cancel the harmful fraction of the outgoing air stream through slot B, it is effective to increase the appropriate amount of outgoing air stream fraction by the set of alignment of the air guiding members. Based on this idea, experiments were undertaken so that each set of alignment guide members. increased air conditions such that the thickness of the air guiding member is 2.9 mm; the alignment pitch of the auxiliary tubes is 10 mm; and the direction of air ejection of the auxiliary pipes is between 120 and 150 relative to the axis of the guide groove of the frame. The results of the experiments are illustrated in Table 1 as well as the result of the above experiments concerning the air guiding members with the straight air guide openings without any taper.

Table 1.

  Diameter of Distance (mm) Diameter of state of launching of the opening between the gold- the opening of the guiding frame ganes of guiding the tubing of the air of the auxiliary air (mm_) (mm) 12 0.8 1.0 Reasonably good 0.8 1.0 Launch of the possible weft although seeming to fly towards _____ _ outside by the slit B 7 0.8 1.0 Launch of the impossible frame 1.6 1, 0 No problem although it seems to be drawn towards the window.

1,2 1,2

7 1.6 1.0

  7 1.6 1.2 Excellent 6 1.2 1.0 Launch of the weft possible although the weft thread contacts the inner surface of the air guide opening ii iii- i

Note from Table 1.-

  Thickness of the air guiding element: 2.9 mm Auxiliary tube No alignment: 10 cm

  5. Air ejection direction: 12-15.

24 8 0 3 1 7

  The complete examination of the experimental results described above led to the following conclusion: in the device for launching the weft constituted by combining the tapered openings for guiding the air of each air guiding member, the main tubing, and the auxiliary tubings, the lower limit of the diameter of the air guide opening is close to 12 mm. In order to further reduce the air guide opening of each guide member while achieving a good launch of the weft, it is necessary to omit the conicity Tp of 1 air guide opening and more establishing the width of each alignment set between the air guiding members so that an appropriate amount of the fraction of the air stream is leaking. through it, the lower limit of the diameter of the air guide opening of each member can then be

near 6 mm.

  Note that the present ivenvImo was anidagée in all the processes described above and on the basis of the above-mentioned first traditional device for launching the weft where an air jet of the main pipe is guided as far as possible through the entire guiding groove of the weft formed by the air guiding apertures which are defined by a series of radially nearly closed air guiding members and the air stream due to the air jet of the air. main tubing is favored by the air jet of an auxiliary tubing close to the air guide groove, thereby further increasing the amount of compressed air for the launch of the

frame.

  Given the above, in the device for launching the weft according to the invention, in order to reduce the dianeter of the air guide opening of each guide member to the point where the launch of the weft derives impossible in traditional devices for launching the -frame with the tapered openings guiding the air guiding members for saving air consumption, the taper of the air guide opening of each organ is omitted and further each air guide alignment set is set to a large and appropriate value, allowing a fraction of the air stream to leak through these sets. It should be noted from the foregoing that an effective launching of the weft can be accomplished with the aid of such an air leak, which makes it possible to obtain a significant saving of the air although a certain amount of leak

air is permitted.

  Referring now to FIGS. 1 to 3, there can be seen a preferred embodiment of the weft launching device of an air jet loom.

according to the invention.

  The device for launching the weft comprises a device 2 for guiding the weft which consists of a certain number of air guiding members 3. Each member 3 has a generally straight section 3a and a section

  generally curved 3b which starts from the right section.

  These sections Sa and 3b form a generally annular section which defines, on its inner peripheral surface 3p, a generally circular opening for guiding

  the air 4, with moreover a slot 5 communicating with the

  air guiding pitch for a weft yarn 12

  in the opening 4 of the air guide can come out.

  The opening 4 is formed straight without any conicity.

  In other words, the inner peripheral surface 3p of the above-mentioned generally annular section consisting of sections Sa and 3b is perpendicular to a vertical plane V parallel to each air guiding member 3 as can be seen on Figure 3. The air guiding members 3 are aligned in the direction of the launch of the frame and each air guiding member is spaced a predetermined distance from the adjacent members. Each air guiding member 3 is fixed

  on a support 6 by securely fixing the lower part

  of the straight section Sa in the throat of the support using an adhesive. The air guide openings of the members in succession constitute a groove 4A for launching the weft by o the weft thread 12 injected by a main pipe 11 moves and is thrown into the crowd of the warp yarns 13. It is necessary to note that the average diameter of the air guide opening 4 is set to a value lower than the value below which the launching of the frame is impossible in a device for launching the frame using the guide members air having respective tapered or conical air guide openings, i.e. less than 12 mm as previously described. In addition, the distances of the spaces formed

  between adjacent air guiding devices (ie

  the alignment sets of the air guiding members) are set to values to prevent the weft yarn from flying out through the slot 5 under

  the influence of the air leak through the sets of

  3. In other words, the alignment sets are set to cancel the air stream fractions leaking through the slots 5 of the air guiding members by means of the air guide members. the fractions of current

  of air leaking through the alignment games. Each set of

  preferably represents not less than 0.8 mm and preferably of the order of 0.8 to 1.6 mm, with the exception of the clearance between the air guiding members between which is placed the tubing auxiliary. The support 6 is fixed in the groove of a support 9 of the comb at the same time as the lower frame of a comb 1. The support 9 is fixedly mounted on the upper section of a rosemary sword 8, which is fixed on a rotary shaft 7 to be able to oscillate in forward and backward directions. The shaft 7 is rotatably supported on a frame 17 of the loom. The mark 15 in Figure 2 denotes the folding of a woven fabric 16. The air guiding support 6 is divided into a number of parts. An auxiliary tubing support 18 is secured using small screws on the end surface of each workpiece, which surface faces the side of the loom opposite the main tubing 11, except for the corresponding surface of the tubing. piece that is placed furthest from the main tubing. An auxiliary pipe 20 in the form of a tube is supported on the support 18 so as to be placed between the straight sections 3a of the adjacent air guiding members 3. As a result, a number of auxiliary tubes 20 are aligned along the guide groove of the weft 4A lying parallel to the air guiding members 3. The hollow interior of the auxiliary tubing 20 communicates with a tube 21 the tube 21 is fixed to the support 18 and extends downwardly along the comb holder 9. A flexible tube 22 is connected at one end to the air introduction tube 21 and at its other end to the air outlet of an air regulating valve 24 mounted firmly on an elongated post 23 which extends between the two opposite sides of the chassis 17 of the trade. An air inlet of the valve 24 is connected to a source of high pressure air (not shown). The valve 24 is constructed and arranged so that a valve member 25 is usually biased in the direction (downwardly in FIG. 2) to open the valve to supply pressurized air to the tube 22 through the action of a spring (not shown) disposed in the valve 24. The member 25 thus biased, solicits, by its lower end section, an oscillating lever 27, one end of which is pivotally attached by an axial pin 26, to the body of the valve 24. A cam follower 28 is rotatably attached to the other end of the lever 27. The roller 28 is arranged to contact the cam surface of a rotary cam 30, which is fixedly mounted on a

  rotating shaft 29 which rotates once per function cycle

  of the loom, that is to say for a movement

24803 1 7

  to and from the comb 1. The cam 30 has a lobe 30a. As a result, the cam follower 28 contacts the lobe 30a, the valve member 25 is urged upwardly by the lever 27 to open the valve 24 to allow the pressurized air to flow to flexible tube 22. It should also be noted that the cam 30 is constructed so that its lobe 30a contacts the roller 28 when the weft thread 12 injected by the main tubing has it next to the corresponding auxiliary tubing 20 Each auxiliary tubing 20 is closed at its top and has an opening 32 on its upper side wall. The apex of each auxiliary tubing 20 is conical and rounded in shape. The opening 32 is formed so that its axis is on a horizontal plane containing the axis G of the guide groove 4A of the frame and crosses the axis 4G at a predetermined angle S. Consequently, the air ejection direction line N of the auxiliary pipe 20 intersects angularly l Vaxe G of the guiding throat of the weft and is directed towards the inner surface of the air guiding opening 4 of the air guiding member 3 which is closer to the side of the loom opposite to the main pipe than the auxiliary pipe 20. It is preferable that the air guiding members placed downstream of each auxiliary pipe 20 have on their air guiding opening surfaces,

  cut portions 33 having the shape of a rounded groove.

  This makes it unnecessary to project the auxiliary tubing into the weft guiding groove 4A, thus preventing a false pitch of the weft at a weft yarn 12 taken by the auxiliary tubing 20

  The mode of operation of the device will be described below.

  above described description of launching the frame.

  When the comb 1 moves back, each air guiding member 3 of the guiding device of the weft 2 which moves with the comb 1 enters the shed 14 of the Els of

  shackle 13, pushing them towards the side. Almost simultaneously

24803 1 7

  Also, each auxiliary tubing 20 also enters the shed of the warp yarns, pushing them to the side by the upper section. From the moment when the chalk wires have come out of the groove 4A for guiding the weft, underpressed air is ejected by the main pipe i1 into the guide groove of the weft 4A, injecting the weft yarn 12 under the influence of the pressurized air thus ejected and the stream of air formed to begin the launch of the frame. Immediately before the leading end. the weft yarn does not reach the vicinity of each auxiliary pipe 20, the lobe 30a of the cam 30starts to contact the cam follower 28, so that the valve member 25 of the air regulating valve 24 is pushed by the lever 27. As a result, the valve 24 opens to let the pressurized air supply

  the auxiliary tubing 20 through the tube 22 and the tube 21.

  Then, the air jet is ejected through the opening 32 of each auxiliary tubing 20 in the predetermined direction. As a result, the weft yarn 12 is driven into the entire guiding groove of the weft 4A, successively being blown off by the air jets of the openings of the tubing to the blades 20 placed in succession, to accomplish the launching of the frame. Each auxiliary tubing 20 is arranged to stop the ejection of the air jet from

  the opening 32 of its tubing when the driving action

  the weft yarn is transmitted to the next auxiliary pipe 20, since the lobe 30a of the cam 30 is separated from the

cam follower 28.

  When the launch of the weft is completed, the high pressure air ejections of the main pipe 11 and the auxiliary pipe farthest from the main pipe 11 stops and the air guiding members 3 and the auxiliary tubing 20 are coming out

  of the crowd by the following advance movement of the comb 1.

  At this time, the weft thread 12 leaves the guide guide opening 4 of each guide member 3 through the slot 5 under the support action of the lower weft son constituting the crowd. Then, the wire 12 is beaten against the folding 15 by the comb 1 for

weave the fabric 16.

  The state of the launching of the above frame will be explained below with reference to FIG. 3. FIG. 3 shows the state of the launch of the frame in the condition having presented the most favorable result in a whole. wide variety of experiments undertaken by varying many factors of the experimental conditions. The experimental conditions for FIG. 3 were as follows: internal diameter D of the air guide opening of each air guiding member 3: 7 mm thickness T of the air guiding member 3 : 2.9 mm, distance C between the air guiding members 3: 1.6 mm, diameter d of the opening 32 of each auxiliary pipe 20: 1 mm, angle of intersection 4 of the line-of-direction N air ejection of the opening 32 of the tubing with respect to the axis of each guide opening of the ar 4: 150, and distance P between adjacent auxiliary tubing

: 100 mm.

  As can be seen in FIG. 3, the weft yarn 12 is attracted to and on the ejection direction line

  air N when approaching the proximity of the tubu-

  20. Then, the weft yarn 12 intersects the axis G along the direction line N and again advances with its direction of advance modified along the theoretical line of reflection R to cut the axis again. G. Then, the weft yarn 12 again changes its direction of advance to advance along the axis G as soon as it has again cut this axis G. Thus the light weight weft yarn 12 is arranged in a position (the center of the air stream formed in the weir guide groove) o the flow velocity of the air stream is the highest, and therefore it appears that this shape of the weft wire indicates the center of the airflow in the throat of

guiding the frame.

  Furthermore, with a previously proposed device for launching the weft (disclosed in US Patent Application No. 149,083), air guiding members having tapered or conical air guide openings are combined. to auxiliary tubings, the theoretical reflection ligia (indicated by the letter R 'in FIG. 3) of the air ejection direction line N

  is formed in a zigzag fashion, with steps gradually decreasing.

  Consequently, this has the effect of an effective and rapid convergence of the air current on the axis G. However, it will be noted by the shape of the reflection line R 'that the turbulence is produced in the current of air if the cross-sectional area of the guiding air aperture of

  each organ decreases. From this point of view, according to the invention

  In this case, the theoretical reflection line R with equal steps is slowly formed and consequently a stable center of the air flow can be formed with a narrow channel for guiding the tram. Finally, air agrees with the G-axis, showing that balanced air leaks take place radially through the alignment sets of a

  row of air guiding members.

  As will be appreciated from reading the foregoing, according to the present invention, in the launcher launcher of the air saving type where the weft yarn is launched into the guide groove of the weft defined by] s air guide openings of a series of air guiding members which are radially almost closed> under the influence of the air jets of the main and auxiliary ducts, the guiding opening air of each member is formed straight without any taper and furthermore the distance of each alignment set is set to allow an appropriate fraction of the air stream to leak. This allows the guiding air opening of the organ to decrease to a point that can not be used in traditional devices launching the frame, thus obtaining a greater air economy. Although there is some leakage in the weft launching device according to the invention, a stable weft transport action is performed, where the weft yarn floats in the weft guide groove. as shown in FIG. 3 by the aid of the leaked air, which is now weaker than the flight resistance of the weft yarn. By

  Therefore, it is possible to reduce the number of tubu-

  Auxiliary lures in comparison to the second traditional device for launching the t-slab above m entioned, and therefore the present invention can greatly improve the device launching the frame using the air guiding members radially almost

  closed, from an economic point of view.

  Of course, the invention is not limited to the embodiment described and shown which has been given by way of example. In particular, it includes all means constituting technical equivalents

  described means, as well as their combinations, if these

  ci are executed according to his spirit and implemented in the framework of the protection as claimed

Claims (7)

R E V E N D I C A T I 0 N S   1. Device for launching the weft pDur an air jet loom, characterized in that it comprises: a tubing (11) for inserting the weft for injecting a weft yarn (12) under the influence of its air jet a number of ur guide members (3) aligned in the direction of launch of the frame, said members being traversed by respective air guide openings (4) which constitute a groove (4A) for guiding the weft by o the weft thread coming from said tubing is launched, each guide member having a slot (5) through which the weft thread exits said air guide opening , an auxiliary pipe (20) arranged to eject an air jet into the guide groove of the frame to form a stream of air in said guide groove means for rendering the guide opening straight   air from each guide member, said means comprises   an inner peripheral surface (3p) of said air guiding member, said inner peripheral surface being perpendicular to a plane (V) parallel to said air guiding members; and means for spacing each air guiding member from adjacent members to cancel fractions of the air stream leaking through the slot of said air guiding member by receding air stream fractions. through the spaces between air guiding members so that the weft yarn is prevented from flying out of the guide groove of the weft by   said slot during the launch of the frame.   2. Device according to claim 1, characterized in that the average diameter of the above-mentioned air guiding opening of each air guiding member (3) does not represent more than 12 mm.   3. Device according to claim 1, characterized in that said spacing means comprises means for establishing the distance (C) between two adjacent air guiding members (3) on a range not representing less than 0.8 mm.   4. Device according to claim 3, characterized in that the aforementioned range is between 0.8 and 1.6 mm.   5. Device according to claim 1, characterized in that the auxiliary pipe (20) above is placed 1o between two adjacent air guiding members, said auxiliary pipe having an opening (32) whose axis intersects the axis (G) of the guide groove of the weft, to a angle between 12 and 150.   6. Device according to claim 5, characterized in that the diameter (d) of the opening of the tubing is between 1.0 and 1.2 mm.   7. Device according to claim 1, characterized in that each air guiding member (3) above has a generally straight section (3a) and a generally curved section (3b) defining on their inner peripheral surfaces (3p). , the right opening Precise air guide & (4).