EP0044933A2 - Traversing device for a cutter for a synthetic-filament cable - Google Patents

Abstract

In a cutting machine for synthetic filament cables, the filament cable (3) is shifted back and forth before entering the pair of cutting rollers (1, 2), i.e. traversed. This invention now provides a teaching of how this traversing movement has to be carried out by the cable guide (5) which is guided back and forth with a grooved drum (10) so that the fiber number line of the cut fiber liner, i.e. optimal, will. In particular, the mathematical formula for the form of the development of the guide groove (9) of the groove drum (10) is given.

Description

The present invention relates to a traversing device for a cutting machine for a synthetic filament cable with a pair of cutting rollers defining a cutting line and consisting of a cutting roller and a pressure roller, the cutting roller having a helically wound cutting edge on its surface, and with a material line in front of the cutting line in the running direction of the material lying, parallel to the cutting line traversing cable guide, on which the filament cable is guided on both sides as a wide band, and which carries out the traversing movement by engaging in the jacket-side guide groove of a rotating groove drum.

A cutting machine for a synthetic filament cable, often also called a cutting convertor, is used to convert the endless filaments of the synthetic filament cable into staple fibers suitable for processing in worsted spinning. In terms of spinning technology, it is desirable that all fibers do not have the same fiber length, but that the fiber length within a certain range varies. One speaks of fiber display lines in this context, and one differentiates in practice between the fiber number display line and the fiber weight display line.

The fiber display line is the diagram of the fiber length as a function of the percentage of fibers in the fiber structure, calculated in terms of number or weight. The considerations of the present invention all relate to the fiber count line. It has now been shown that the best spinning properties are achieved when cutting synthetic filament cables if the fiber count line of the cut fiber material fulfills a very specific law; namely if the fiber number display line has a substantially linear course, similar to the course e.g. certain natural fibers, e.g. certain types of wool. The course of the fiber number line of a cut fiber cable can now be influenced in various known ways, e.g. by using a multi-speed cutting roller with different pitch of the knives, e.g. according to Japanese Patent Application No. Sho 37-14431, or by using a traversing device for the filament cable as in the preamble of the present invention. The first-mentioned, known method has the disadvantage that only a limited adaptability is available, since only the inclination of the number of fibers can be determined by the cable entry width and thus different cutting rolls are also required for different middle stacks. For this purpose, such cutting rollers with different pitch of the knife or knives are complicated and expensive.

In the solutions known from practice according to the preamble of this invention, the use of a grooved drum for the movement of the traversing device is proposed, in which the shape of the development of the guide groove either corresponds to a sinusoidal curve or. has a linear course, possibly with a different slope. These known forms of processing the guide groove have the disadvantage that the fiber number display line obtained with them deviates too much from the optimally aimed for fiber number display line with a linear course. The consequence of these unfavorable fiber count lines is poor product quality.

The object of the present invention is to eliminate the disadvantages of the previously cited prior art in a traversing device for a cutting machine according to the above-mentioned preamble and to propose a grooved drum for the traversing device by means of which the cutting of the filament cable into fibers with an optimal, linear fiber number curve ensures becomes. This object is achieved with a traversing device according to the features of claim 1.

Further advantageous embodiments are described in claims 2 to 5.

• Fig. 1 die Traversiervorrichtung in einer schematischen, stark vereinfachten Darstellung.
• Fig. 2 drei Abwicklungen a bis c von Formen der Führung der Nutentrommel nach dem Stand der Technik.
• Fig. 3 die den drei Abwicklungen a bis c der Fig. 2 entsprechenden Faseranzahlschaulinien A bis C sowie die der Form der Führungsnut nach Fig. 4 entsprechende Faseranzahlschaulinie D mit linearem, optimalem Verlauf.
• Fig. 4 die Abwicklung der Form der Führungsnut nach der Erfindung graphisch für einen bestimmten Spezialfall, bei welchem die gewünschte, kürzeste Stapellänge L_min gleich der mit einer bestimmten Schneidwalze minimal erreichbaren Stapellänge ist.
• Fig. 5 eine Variante der erfindungsgemässen Traversiervorrichtung mit zwei durch eine einzige Nutentrommel angetriebenen Traversiervorrichtungen für zwei zugeführte Filamentkabel.
• Fig. 6 eine weitere Variante der erfindungsgemässen Traversiervorrichtung mit zwei je durch eine eigene Nutentrommel angetriebenen Traversiervorrichtungen für zwei zugeführte Filamentkabel.

The invention is explained in more detail below with the aid of exemplary embodiments and the drawings. It shows:

• Fig. 1 shows the traversing device in a schematic, greatly simplified representation.
• Fig. 2 three developments a to c of forms of guiding the grooved drum according to the prior art.
• 3 shows the number of fiber lines A to C corresponding to the three developments a to c of FIG. 2 and the fiber number line D corresponding to the shape of the guide groove according to FIG. 4 with a linear, optimal course.
• Fig. 4 shows the development of the shape of the guide groove according to the invention graphically for a specific special case in which the desired, shortest stack length L _{min is} equal to the minimum stack length achievable with a particular cutting roller.
• 5 shows a variant of the traversing device according to the invention with two traversing devices for two supplied filament cables driven by a single grooved drum.
• 6 shows a further variant of the traversing device according to the invention with two traversing devices, each driven by its own grooved drum, for two supplied filament cables.

In Fig. 1, 1 denotes the cutting roller and 2 the pressure roller of a pair of cutting rollers known per se. At their contact line, where the filament cable 3 drawn between them is cut into staple fibers, the two rollers 1 and 2 define a cutting line f. The cutting roller 1 has on its surface helically wound cutting edges p which run parallel to one another and at an equal distance and with a pitch angle α.

The filament cable 3, which moves in the direction of the arrow m and is fed or conveyed by appropriate means, not shown, as a broadly designed cable, consists in front of the pair of rollers 1/2 of a very large number of endless filaments which are connected to one another in the cable assembly lie strictly parallel. After leaving the pair of rollers 1/2, or the cutting line f, the cable 3a now consists of staggered, trapezoidal (at least in the 1st approximation) coulter 4a, 4b, 4c etc., which are in principle completely separated from one another and thus the cable 3a should take every cohesion. In reality, however, the cut cable 3a also remains somewhat cohesive, so that even after the cutting operation it is present as a broad, coherent nonwoven fabric and can be transported further.

In order to obtain an inclination of the fiber number line, the filament cable 3 must make a traversing movement in relation to the pair of rollers 1/2. It is now known to carry out the traversing movement of the filament cable 3 by means of a cable guide 5 located at a distance a from the cutting line f (viewed in the transport direction of the filament cable 3). The cable guide 5 consists essentially of a horizontal rod 6 which has two side guides 7, e.g. in the form of a short pencil. The distance between the two side guides 7, which can be adjustable (not shown), is chosen so that the filament cable 3 on the bar section lying between the two side guides 7 in a wide-ranging form, i.e. as a closed cable, is fed on both sides. The filament cable 3 must therefore be guided laterally in such a way that it follows every lateral displacement of the cable guide 5, but without being compressed on the side guides.

The lateral displacement of the cable guide 5 is carried out according to a known method by engaging the rod 6, e.g. by means of a roller 8 connected to it, into the jacket-side guide groove 9 of a rotating groove drum 10. However, it should already be noted here that instead of a grooved drum 10, any other type of curve guidance, articulated polygons, etc. is conceivable in the context of this invention.

The present invention is now based on the knowledge that the traversing movement is not only useful for the above-mentioned purpose, but that it also has a decisive influence on the shape of the number-of-fibers line of the cut fibers.

2 a) to c) show three developments of the shape of the guide groove 9 of the groove drum 10, which are known from practice.

2 a) shows a sinusoidal course of the guide groove, FIG. 2 b) a simple linear course, while in FIG. 2 c) the case is shown in which the speed of the traversing movement at the reversal points of the movement compared to the average traversing speed should be increased. These three forms of guide groove 9 are known everywhere in practice and are used primarily in connection with traversing thread guides for the placement of a longitudinally oriented fiber web, such as a yarn or a sliver, on the surface of a bobbin. Such slot shapes were therefore particularly with regard to the problems of coil formation (e.g. the need to avoid material accumulation at the coil edges, which is why a higher Ge speed of the thread guide at the reversal points, as is shown in FIG. 2 c) is developed) and allows to overcome such problems. However, these groove shapes have so far also been used in the cutting machine forming the subject of this invention, without taking into account that the traversing of the filament cable 3 must meet completely different requirements here. The lateral displacement of the filament cable 3 always causes a correction of the length of the cut fibers obtained by the distance between two knives following one another on the cutting roller surface, with which the fiber number line of the cut fiber material is influenced.

FIG. 3 shows the three fiber number display lines A to C corresponding to the shapes of the guide groove according to FIGS. 2 a) to c) compared with the experience-based optimal number of fiber display line D with a linear course. As can be seen, all curves A to C deviate more or less markedly from the optimal course D. This is inevitably reflected in the quality of the products made with the corresponding cut fibers.

The present invention now gives a clear teaching about the shape of the guide groove 9, which corresponds to a fiber number line with a linear course D as in FIG. 3. In order to achieve this, the shape of the settlement should lie in a plane of the guide groove 9 according to the formula of claim 1.

bestimmt. Das bedeutet, dass die mittlere Stapellänge H verschieden von L sein kann und somit z.B. auf einer 88er-Schneidwalze (L = 88) je nach Kurvenform beliebige mittlere Stapellängen zwischen 70 und 90 mm geschnitten werden können. Es ist iedoch vorteilhaft, wenn H =

im näheren Bereich von

gewählt wird.In Fig. 4, the formula of claim 1 for a specific special case, namely when the desired shortest stack length L _{min should be} equal to the minimum stack length achievable with a particular cutting roller and the Desired average stack length H equals the cutting roller stack length L, graphically constructed. However, H does not have to be equal to L, because the average stack length H is not determined by the cutting roller, but by

certainly. This means that the average stack length H can be different from L and thus any average stack length between 70 and 90 mm can be cut on an 88-size cutting roller (L = 88), depending on the shape of the curve. However, it is advantageous if H =

in the closer range of

is chosen.

The two lines p ₁ and p ₂ , which in the direction of transport of the material include an angle α = cutting edge pitch angle and are represented by the arrow m (corresponding to the illustration in FIG. 1), represent two knives mounted next to one another on the surface of the cutting roller, the distance between them is denoted by T.

The shape of the guide groove has now been graphically constructed in FIG. 4 for the special case in which the minimum fiber length L _{min is} equal to the knife distance T (L _min = T). This corresponds to the case in which the fibers are cut perpendicular to the cutting edges at a specific moment of the traversing movement.

If H and L _{min were} given or selected, then L _max is automatically known. Furthermore, in Fig. 4 with f the cutting line between the pair of cutting rollers 1/2 and with line g the position of the cable guide 5 is shown. The distance between the lines f and g is denoted by a (according to the formula of claim 1).

The construction of the curve b as a function of the central angle ϑ of the unwound drum surface is based on the graphical representation, wherein ϑ only varies between 0 and 180 ⁰ , so that only half of the unwound drum surface or the development of the guide groove 9 is shown. The other half is of course a mirror image.

The formula for b given in claim 1 now allows the shape of the development of the guide groove to be calculated without having to rely on a graphic representation. The relationships between the shown graphical construction of the curve b = f (ϑ) according to the example of FIG. 4 and the mathematical formula of claim 1 are clearly evident to every mathematician and need not be explained further here.

Of course, the shape of the development of the guide groove 9 can also be constructed or calculated both graphically and arithmetically in the event that L _min > T applies.

The shape of the number of fibers corresponding to the shape of the guide groove 9 calculated according to the formula of claim 1 or graphically constructed according to the example of FIG. 4 then has a linear course, as represented by D in FIG. 3.

If now, as in the example in FIG. 1, a single filament cable 3 is fed to the cutting roller pair 1/2, it is clear that the length of the cut fibers varies depending on the position of the cable guide 5: the cable guide 5 is in its extreme left position , then the longest fibers are cut (see FIG. 4), while when the cable guide 5 reaches the extreme right position, the shortest fibers are formed. In other words: although the fiber count line of the fibers in the cut filament cable 3a is optimal, ie linear, the spatial distribution of the fibers in the longitudinal direction of the cable 3a is extremely periodic, with a periodicity which corresponds to that of the traversing movement of the cable guide 5. In order to eliminate this disadvantage, it is advisable to feed more than a single filament cable, for example two together via different, phase-shifted, traversing cable guides, to the cutting roller pair 1/2. This automatically results in a so-called doubling effect, in which a zone of a first filament cable with short fibers is overlapped with a zone of a second filament cable with long fibers. Virtually fibers of different lengths are thus present in each cross section of the overlapped filament cable.

5 and 6 each show an example of a cutting machine working with two filament cables (not shown) guided in two different planes. In Fig. 5 it is shown how a cable guide 11 and 12 is provided for each of the filament cables, which are essentially one above the other so that the two filament cables are guided in the overlapped state by the pair of cutting rollers (only the cutting roller 1 is shown), and how each cable guide 11 and 12 is caused to traverse by engaging the guide groove 13 of a common rotating groove drum 14, the guide groove 13 fulfilling the relationship of claim 1. If, intervene as in the example shown, the two cable guides 11 and 12 in two diametrically opposite points of the guide groove 13 of the grooved drum 14, one automatically gets a phase shift between the Traversierbewegungen the two cable guides 180 ^0th Other phase shifts are of course also easily conceivable.

6, on the other hand, shows the case in which the two cable guides 15 and 16 engage in two separate groove drums 17 and 18, the two groove drums 17 and 18 having the same dimensions and the same shape of the guide groove 15a, 16a, or different dimensions which can have shapes. Their mutual phase shift can also be chosen arbitrarily.

The traversing device according to the invention can of course also be used with more than two filament cables, advantageously in the overlapped state, the rule being that the larger the doubling, the better the distribution of the cut fibers in the cut cable 3a.

As far as the shape of the fiber count line is concerned, a single filament cable, which traverses with the device according to the invention, is sufficient to ensure an optimal, linear course of the same.

Claims (5)

1. traversing device for a cutting machine for a synthetic filament cable with a cutting line (f) defining, consisting of a cutting roller (1) and a pressure roller (2) consisting of a pair of cutting rollers (1/2), the cutting roller wound helically on its surface, in the same _D i punch has cutting edges running parallel to one another, and with a cable guide (5; 11, 12; 15, 16) lying in front of the cutting line (f) in the direction of travel of the material and traversing parallel to the cutting line (f), on which the filament cable ( 3) is guided on both sides as a wide belt and which carries out the traversing movement by engaging in the casing-side guide groove (9; 13) of a rotating groove drum (10; 14; 17, 18), characterized in that the shape of the development of the guide groove (9 ; 13) fulfills the following relationship:

where b = traverse path of the cable routing (5; 11.12; 15.16) a = distance between cable guide (5; 11.12; 15.16) and cutting line (f) α = cutting edge pitch angle L _max ⁼ maximum fiber length in the fiber structure (3a) L _min = minimum fiber length in the ^fiber bandage (3a) ϑ = central angle of the unwound drum surface L = Cutting roller stack length =

where T = distance between two knives placed side by side on the surface of the cutting roller (l) and G = number of cutting edge passes. 2. traversing device according to claim 1, characterized in that two filament cables are fed to the pair of cutting rollers (1/2) and cut in the overlapped state, that each filament cable in a cable guide (11, 12), in which it runs as a wide band, on both sides is guided, and that the two cable guides (11, 12) are essentially one above the other and by engaging in the guide groove (13) of a common, rotating groove drum (14), the guide groove (13) fulfilling the relationship according to claim 1, for Traversal can be arranged. 3. traversing device according to claim 2, characterized in that the two cable guides (11, 12) engage at two diametrically opposite points of the guide groove (13) of the groove drum (14). 4. traversing device according to claim 1, characterized in that two filament cables are fed to the cutting roller pair (1/2) and cut in the overlapped state, that each filament cable in a cable guide (15, 16), in which it runs as a wide band, on both sides and that the two cable guides (15, 16) are essentially one above the other and each by means of engaging in the guide groove (15a, 16a) of its own rotating groove drum (17, 18), the guide groove fulfilling the relationship according to claim 1, be prompted to traverse. 5. traversing device according to claim 4, characterized in that the two groove drums (17,18) have the same dimensions and the same shape of the guide groove (15a, 16a) and the cable guides (15,16) with a mutual phase shift of essentially one stroke of their traversing motion.

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