This invention relates to the field of textile machines, and in particular to supply sets which, in said machines, draw the textile thread by friction, sending it toward a take-up bobbin. At the current state of the art, said supply sets as disclosed in DE 2 054 151 A, which corresponds to the preamble of claim 1, are composed of two like coaxial gearwheels that are equipped with n teeth and engage frontally. The teeth are shaped in a particular way, known to one skilled in the art, and have the characteristic that they exhibit an inclined or curved profile, such that each pair of mutually engaging teeth forms a V-shaped groove that is open toward the outer truncated circumferences of said gearwheels.
The textile thread is made to follow a path between a supply spindle and a take-up bobbin, in such a way that the thread grips tightly along a certain arc on said gearwheels; it is held between a number of V-shaped grooves corresponding to this gripping arc, arranges itself in a zig-zag pattern on said gearwheels, and is thus drawn, under the action of friction alone, by the rotation of the set of this supply device that is composed of the two wheels described above.
By varying the axial distance between the two frontally engaging gearwheels, the opposing teeth of each pair form V-shaped grooves with different distances from the vertices of the axes of rotation of the wheels themselves, but the thread that is to be drawn is arranged tangentially to said wheel and to the projections that are arranged on the teeth of said wheels in accordance with a constant diameter of rotation. Thus, by varying the relative positions between the two wheels that comprise a supply set, a drawing effect of greater or lesser magnitude is obtained, and this varies the angle at which the thread is arranged on the zig-zag path on the teeth and thus varies the intensity of the friction.
At present, this kind of variation can be achieved only using supply devices that are of different geometries or by placing the two wheels that comprise a set different distances apart.
The intention of inventor of this invention was to provide a supply set which would solve this problem and would offer quick and flexible maneuverability without requiring the use of spacers or different supply units.
To accomplish this, he developed a supply set according to claim 1 that was composed of two like gearwheels that have shapes and geometric characteristics which make it possible to vary the axial distance between the two wheels simply by varying their relative positions just by turning them.
A more detailed description of a preferred embodiment of the invention will now be given, also referring to the attached drawings, where:
Fig. 1 shows how textile thread 8, which comes from a supply station 7, is wound onto a take-up bobbin 6 after being drawn by friction by a supply set 5 under the action of above-described gripping arc α. This arc can be modified using known techniques by moving a pulley 10 over an arc 11 in the direction indicated by the arrows.
Fig. 3 shows the shape of the profile, in section, of wheels 1, 1' that comprise a supply set 5 according to the invention, in which teeth 3, which are arranged at diametrically opposed positions that are shown better in Figs. 2 and 3, have two projections 3c, 3d that have different axial heights h1, h2, whereby said heights can be ≥ 0.
Also recesses 4, which are visible in Fig. 2 and with which said projections 3c, 3d are made to mate, have differing depths p1, p2, which can be ≥ 0 and which are better depicted in Figs. 4 and 5. These latter figures also show how two wheels 1, 1' which comprise a set are arranged a certain distance apart and how they are arranged after they have completed a relative rotation that has caused projections 3d, which have a greater height h2, to mate with recesses 4 of lesser depth p2.
In accordance with the configurations depicted in Figs. 4 and 5, the thread is arranged, in its drawing arc α on supply set 5, in a zig-zag pattern between the different adjacent teeth, in the two cases following the paths indicated in Figs. 6 and 7, respectively.
As indicated, angle β that is formed by the different segments of the zig-zag varies, and consequently the drawing effect that is imparted to the thread by the set and is greater in the case shown in Figs. 4 and 6 than in Figs. 5 and 7 also varies.
As can be deduced, the diameter of the meshing arc remains constant, but the thread is always arranged tangentially to projections 3c, 3d, the distances between which and the center of rotation remain constant.
The embodiment that is described above and is shown in the figures refers to the case where n teeth 3 and an equal number of recesses 4 are both subdivided into only two groups that have differing axial projections and, respectively, different depths, with teeth 3 and recesses 4 alternating in such a way that said two projections 3c, 3d and two recesses 4, which have differing heights h and depths p, are arranged consecutively. Other embodiments are possible, however, in which both the projections and the recesses are subdivided into a larger number of groups that have similar characteristics and dimensions, such that it is possible, by appropriately arranging the elements that constitute the different groups, to obtain a larger number of combinations of projections and recesses that can produce different configurations with different axial distances between frontally opposing wheels 1, 1'.
This produces the technical result desired by the inventor, i.e., that of providing a supply set that is composed exclusively of two like gearwheels and is able to operate under different operating conditions that can be achieved simply by rotating the two wheels to a predetermined extent and locking them in the desired position.