US2879676A - Manufacture of spinning nozzles - Google Patents

Description

March 31, 1959 M. BUR'KHARDT ETAL MANUFACTURE OF SPINNING NOZZLES Filed Feb. 24, 1953 v V, x% 1 INVENTORS MAX BURKHARDT EMIL GRAFRIED BY GRETELORE RAUNECKER ne Hum Maw R0 CAL ATTORNEYS United 2,879,676 MANUFACTURE OF SPINNING NOZZLES Max Burkhardt, Hanan (Main), Emil Grafried, Grossanheim (Main), and Gretelore Raunecker, Hanan (Main), Germany, assignors to W. C. Heraeus G.m.b.H., Hanan ma Wholly synthetic filaments, more particularly filaments of polyamides and similar poly-condensates and other polymer substances, are generally produced by forcing the ready-prepared substance in a molten or plastic state through spinning apertures, the substance then solidifying to form filaments when cooling down. This procedure places much higher requirements upon the spinning elements than the methods known in the manufacture of rayon filaments and of viscose wool. The temperatures lie up to 200 higher, and the pressures exceed those of the earlier methods. The spinning apertures, which may for example have, at the outlet side of the spinning disc, a diameter of one tenth, or a few tenths, of a millimetre, must retain their accurate dimension at these relatively high temperatures and pressures. Although the spinning apertures are additionally exposed at these high pressures and temperatures, to constant friction by the extruded synthetic resin substance, they must retain their high gloss and must not become rough. These qualities of the surface of the spinning apertures must also not get lost during cleaning with concentrated acids.

In order to comply with these high requirements, it has already been proposed to provide spinning discs consisting of acid-resistant steels, equipped with insertion pieces of precious metals in which fine bores are drilled to form the spinning passages. Furthermore, it has already been proposed to provide the spinning apertures with a chromium coating. This latter suggestion, however, is extremely difficult to carry out in practice, as will be readily appreciated by those skilled in the art.

When using preformed insertion pieces of precious metal, the diameter of the spinning apertures cannot be reduced below a certain limit, and more particularly it is impossible to produce in this manner spinning apertures of certain desirable shapes, for example, long spinning apertures of fine cylinder shape. The present invention has for an object to enable spinning nozzles suitable for the production of wholly synthetic filaments to be produced having spinning passages of any shape required by the spinning technique and which, at the same time, may be produced directly with the desired high-gloss polish.

With this object in view, according to the invention, the spinning passages are provided in the spinning discswhich, in a known manner, may consist, for example, of steel plates of 6 to 10 mms. thicknessby the following method: I

First a core is made having the shape of the spinning aperture to be produced. On this core there is deposited a layer of hard metal resistant to nitric acid and having a thickness of, for example, 0.5 to 3 mms., which may be done by a known method. We have found particularly suitable hard base metals, such as chromium or chromium alloys, the metal being preferably galvanically deposited on the core. If the core does not consist of metallic material, a thin intermediate metal layer is first applied, for example, by vapour deposition in a vacuum, whereafter the hard chromium coating is gales atef r" 2,879,676 Patented Mar. 31, 1959 plied to the core may also itself be deposited by other 3 methods, e.g., by high vacuum vapour. deposition, cathode sputtering, or gas decomposition.

The material for the core is so selected that it may be removed. chemically without damage to the metal deposited thereon. Preferably the core is made of an iron-nickel alloy; this alloy may readily be removed from ashell of chromium by being dissolved in nitric acid.

The shell body thus obtained is then inserted into a corresponding aperture provided in the spinning disc and may, if desired or necessary, be further secured therein by known methods, such as pressing, swaging, soldering or brazing; a firm seal at the edge may also besensured by additional galvanic deposition of'metal', for example of chromium. If the core, the shape of which corresponds to the desired spinning aperture, is not of a's'lim cone shape, it is advisable'to grind the shell body externally to a slim cone shape and to insert it intoa correspondingly shaped aperture of the spinning disc, thereby ensuring aparticularly firm seating.

In order that the invention may be more readily understood, it will now be described by way of example with reference to the accompanying drawing, in which:

Fig. 1 is a cross-section of a small portion of a spinning disc.

Fig. 2 is a similar section of the core for a spinning nozzle.

Fig. 3 similarly shows the core with the shell deposited thereon, and

Fig. 4 is a view similar to Figure 1 showing the corresponding part of the completed spinning disc equipped with a nozzle.

Referring now to the drawing, a spinning disc A, of which a small portion is shown in Figure 1, and having a thickness of 6 mms. is desired to be provided with spinning apertures having the shape shown in Fig. 2. The spinning apertures in this example have a hyperboloidal section. The diameter may, for example, be

a 1 mm. at the point of entry, the aperture being reduced at the outlet point to an approximately cylindrical passage having a diameter of 0.12 mms.

According to the invention, first a core as shown at B in Fig. 2, is made of a metal soluble in nitric acid, for example of an iron-nickel alloy. On to this core a hard chromium layer C (Figure 3) having the thickness of 2 mms. is then galvanically deposited. This layer is ground down externally along the circumference D to produce a slim cone fitting into the conical aperture of the spinning disc A (Figure 1).

Finally, the shell C is, after the core B has been removed by being dissolved in nitric acid, inserted according to Figure 4, into the conical recess of the spinning disc A having a thickness of 3 to 6 mms. and, if necessary or desired, may be additionally secured and sealed by one of the above-mentioned methods.

In this manner spinning apertures may be produced without difiiculty having a cylindrical passage with a diameter of as little as 0.1 mm. or even less, a problem which cannot be solved with drilled precious metal insertions. Moreover, the inner surface of the spinning passages will be produced directly with a high-gloss polish provided only that the core, which can be readily machined or otherwise worked from its outer side, is made with a high polish. This method also is not limited to the use of precious metals thus permitting the utilisation of the very great hardness and chemical resistance of chromium. It should be particularly stressed that the illustrated form of the spinning aperture is only given by way of example and that, in fact, the new method makes it possible for the spinning apertures to be produced having any of a variety of shapes desirable for reasons of the spinning technique and constituted, for example, by a combination of cylindrical and conical parts, or having a vertical section composed of curves of different nature. The fine spinning passages may also be arranged to project beyond the :outer surface of the spinning discs thus ensuring further advantages in special cases.

We claim:

1. A method for the manufacture of spinning nozzles, wherein spinning apertures have a hyperboloidal section, comprising making cores having the desired hyperboloidal shape of the spinning apertures to be produced, depositing on each of the cores 2. layer of chromium of snflicient thickness to form a shell wherein the outer surface may e sh p d o a desired f m i din the surfa e i t h l to a u a nt o nisa term, em n the cores from the shells by dissolving the same, providing spinning discs having openings of conical form suitably shaped for receiving the shell bodies, inserting the ground chromium shell bodies into the openings of the discs, and securing said shell bodies in said openings.

2. A method for the manufacture of spinning nozzles,

wherein spinning apertures have a significantly curved section, comprising making cores having the desired curved shape of the spinning apertures to be produced, depositing on each of the cores a layer of chromium of sufficient thickness to form a shell wherein the outer surface may be shaped to a desired form, grinding the outer surface of the shells to a regular continuous conical form, removing the cores frornthe shells by dissolving the same, providing spinning discs having openings of conical form suitably shaped for receiving the shell bodies, inserting the ground chromium shell bodies into the openings of the spinning discs, and securing said shell bodies in said openings.

References Cited in the file of this patent UNITED STATES PATENTS 1,604,216 Brainin Get. 26, 1926 1,654,936 Jones Jan. 3, 1928 1,672,644 Hoffman et al. June 5, 1928 1,708,715 "r-'--"."--..'---'r'" re--,Qr' 1. 1 1 6 9 r Ave 44 2 0 8 0 Prunes A r .2 3,408,713 Webb s Oct. '1, 1946 2,422,612, Home June 17, 1947' 2361,64!) Hallberg .Feb. 15, 1949

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