EP0294576A1 - Synthetic projectile and operating device in looms - Google Patents

Abstract

The plastic projectile with an assigned projectile opener has a projectile clamp (17) with arcuate sections (24a, 24b). The projectile opener (31) exerts forces on these sections both transversely (4a, 4b) and longitudinally (50a, 60a) to the firing direction for simultaneous opening and positioning with respect to these two directions. The projectile opener does not touch a through opening (19) of the plastic housing (8). This eliminates the problem of wear and tear when positioning on the plastic housing earlier. A projectile opener made of abrasion-resistant, impact-resistant plastic enables oil-free operation and the highest fabric quality.

Description

The invention relates to a gripper projectile with a projectile clamp and a plastic housing and with at least one assigned projectile opener for opening and positioning the projectile during thread transfer in weaving machines.

Plastic projectiles have been known for a long time. Compared to the steel projectiles that are still mostly used, they allow in principle higher input performance thanks to their lower weight. However, the lower mechanical strength of the plastic parts used leads to new problems in terms of strength, wear, service life and service intervals. A big problem arises here in particular when opening and centering the projectile during thread transfer. The projectile clamp must be spread open by a projectile opener transversely to the weft direction and positioned exactly along the weft direction for thread transfer so that no thread losers occur. This has so far been achieved with a metallic projectile opener, which spreads the metallic projectile clamp across the shot direction (and thus also centers in this direction) and through a center hole in the projectile housing, onto which the flanks of the projectile opener run and thus the projectile in the shot direction position. This principle was used for steel projectiles as well as for projectiles with plastic housings. With the plastic housings, however, high wear and deformations occur at the contact points of the center hole. The positioning becomes poor and thread loosening inevitably occurs. This results in high service costs and the service life of the plastic projectiles is unsatisfactorily short, especially at high machine speeds.

In order to be able to meet high quality demands on the fabric produced, oil stains must never get into the fabric. With a metallic projectile opener, which has to spread the metallic projectile clamp, minimal oil lubrication is essential. It is difficult and expensive to meter them precisely and to prevent oil traces from getting into the tissue. Solutions are therefore sought without using oil.

It is an object of the present invention to find a solution to the problems mentioned and to create a plastic projectile with an associated opening and positioning device, which enables higher insertion rates with high fabric quality, with high operational reliability and low service requirements.

This object is achieved according to the invention in that the projectile clamp of the plastic projectile has two arcuate sections which correspond to curved side surfaces of the projectile opener, whereby the projectile opener exerts forces on the projectile clamp both transversely and longitudinally to the weft direction for simultaneous opening and positioning with respect to these two directions, and that the plastic housing has a through opening, the limitation of which does not touch the projectile opener during the opening process.

Advantageous designs can have arcuate sections in the form of circular sectors. This results in favorable geometric conditions and simple manufacture. The circle sectors can have opening angles of at least 90 ° each and thus result in a balanced pressure distribution over a relatively large area during the opening and centering process. Advantageously, the arcuate sections can also be in the direction of movement of the projectile opener, i.e. perpendicular to the shooting path, the corresponding inner flank or outer flank of the projectile opener and be slightly rounded.

With a projectile opener made of abrasion-resistant, impact-resistant plastic assigned to the projectile, oil-free operation can be achieved. With the previous center hole in the plastic housing, this is not possible because of the then unfavorable plastic-plastic friction pairing.

• Fig. 1 einen Teil eines bisherigen Greiferprojek­tils mit Oeffner und Zentrierfunktion;
• Fig. 2 einen Teil eines erfindungsgemässen Projek­tils mit Oeffner und Zentrierfunktion;
• Fig. 3 eine schematische Darstellung der auftreten­den Kräfte beim Oeffnen und Zentrieren am bogenförmigen Abschnitt der Projektilklammer;
• Fig. 4a, b ein Greiferprojektil und dessen Projektil­klammer; halb geöffnet durch einen Projek­tilöffner;
• Fig. 5a, b, c die hintere Hälfte eines Projektils von oben und in zwei dazu senkrechten Schnitten mit einem Projektilöffner.

The invention is explained in more detail below on the basis of exemplary embodiments in conjunction with the drawing. It shows:

• Figure 1 shows a part of a previous gripper projectile with opener and centering function.
• 2 shows a part of a projectile according to the invention with an opener and centering function;
• Figure 3 is a schematic representation of the forces occurring when opening and centering on the arcuate portion of the projectile clamp.
• 4a, b a gripper projectile and its projectile clamp; half opened by a projectile opener;
• 5a, b, c the rear half of a projectile from above and in two sections perpendicular thereto with a projectile opener.

The previous embodiment of FIG. 1 shows a plastic housing 8 of the projectile with a center hole 9 and two projectile clamp legs 7a, 7b. A projectile opener, not shown, passes through a variable area 11 during the opening and centering actuation, which is delimited by contact surfaces 14a, 14b of the projectile clamp legs on the one hand and by sections 12, 13 of the centering hole 9 on the other. When the clip is opened, the projectile opener first exerts forces 4a, 4b on the legs 7a, 7b. In the further course of the opening movement, the projectile opener runs onto the segments 12, 13, with the application of forces 2 and 3, onto the plastic housing. This positions the projectile.

2, however, no forces are exerted on the relatively sensitive plastic housing 8. The clamp legs 17a, 17b each have an arcuate section 24a, 24b. A through opening 19 in the housing 8 is not touched anywhere by the projectile opener, not shown. The projectile opener covers only an area 21 during its actuation, which is essentially limited solely by the arcuate sections 24a, 24b. In addition to the forces 4a, 4b transversely to the firing direction, the projectile opener also simultaneously exerts forces 5a and 5b and 6a and 6b along the firing direction X on the arcuate sections 24a, 24b.

These forces are shown schematically for one side (a) in FIG. 3, with a circular sector as an arcuate section 24a and an opening angle 2α. This opening angle is advantageously chosen to be relatively large, For example at least 90 °, with which the force components 50a and 60a can be chosen to be correspondingly large in the positive and negative firing direction X (proportional to sine α).

4a shows an entire plastic projectile with projectile opener 31; 4b shows the projectile clip 17. The plastic housing 8 is connected to the clip 17 with a connecting pin 23 behind the projectile head 22. The projectile opener 31 is moved in the direction 36, running onto the clamp sections 24a, 24b and opening the clamp 27 with clamping pieces 27a, 27b for receiving a thread 26 fed by a thread feeder (not shown). The projectile oiler 31 holds the projectile for thread take-over over the arcuate sections 24a, 24b exactly in the prescribed optimal position.

5a, b, c show the opening and centering function of arcuate sections 24a, 24b and projectile opener 31 from different sides, in plan 5a and in two orthogonal sections A-A, B-B. The arcuate sections 24a, 24b are here also slightly rounded perpendicular to the firing path X and adapted to the corresponding flanks of the projectile opener. 5c shows the inner flank 33 and the outer flank 34 and FIG. 5b the side flanks 32a, 32b of the projectile opener, which run in the direction of movement 36 onto the arcuate sections 24a, 24b.

In contrast to the earlier centering hole 9 (from FIG. 1), the functionless through opening 19 is completely uncritical and also easy to manufacture. It does not have to have a precise shape and position. Your area and especially the wall thickness of the plastic cover 8 can be small here. Correspondingly more space is then available for the optimal dimensioning of the clip and the other parts of the projectile.

In a particularly advantageous embodiment, a projectile opener 31 made of abrasion-resistant, impact-resistant plastic is used, with which oil-free operation is possible.

With the present invention, thanks to significantly improved positioning, less play between the projectile and the racquet was achieved before the launch. This, in turn, reduces the impact load and wear on the plastic housing during firing, thus increasing performance with regard to this function. Overall, in addition to increased fabric quality and reliability of the looms, the lifespan was increased by a multiple.

Claims (5)

1. Gripper projectile with a projectile clamp and a plastic housing and with at least one assigned projectile opener, characterized in that the projectile clamp (17) has two arcuate sections (24a, 24b) which correspond to curved side surfaces (32a, 32b) of the projectile opener, which means that the projectile opener (31) exerts forces on the projectile clamp both transversely (4a, 4b) and longitudinally (50a, 60a) to the firing direction for simultaneous opening and positioning with respect to these two directions, and that the plastic housing (8) has a through opening (19), the Limit never touches the projectile opener during the opening process. 2. Projectile clamp according to claim 1, characterized in that the arcuate sections are formed by circular sectors. 3. gripper projectile according to claim 2, characterized in that the circular sectors have an opening angle of at least 90 °. 4. Gripper projectile according to claim 1, characterized in that the arcuate sections are also adapted and slightly rounded in the direction of movement of the projectile opener, ie perpendicular to the firing path (X), the corresponding inner flank (33) or outer flank (34) of the projectile opener. 5. gripper projectile according to claim l, characterized in that the associated projectile opener consists of abrasion-resistant, impact-resistant plastic.

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