DE2254616B2 - Method for drawing a crystalline body of predetermined cross section from a melt film - Google Patents

Description

Tube or in the form of a plate with a double axle [nung.

Embodiments are explained He _f-making to the figures of. It shows

F i g · 1 is a partially sectioned vertical view of an im Furnace equipment used in the context of the invention,

F i g. Fig. 2 is a partially sectioned vertical view, on a larger scale, of a crucible, one of Shaping part and a heat exchanger arrangement, as they are in the establishment of F i g. 1 for growing crystals in a twisted, tubular hollow body are provided with a rectangular cross-section,

Fig. 3 is a top view of part of the molding part according to FIG. 2,

FIG. 4 is a partial view of the device of FIG to illustrate the initial stage of the formation of a twisted, tubular hollow body with a rectangular cross-section,

F i g. 5 the crystal growth with the aid of the device of FIG. 2 and 3 formed bodies,

F i g. 6 is a partial view of a crucible and a molding similar to FIG. 2, this one Case, however, for crystal growth a <; s rod of circular Cross-section of a circular bore that is spirally guided in the longitudinal direction having,

F i g. 7 is a top view of the molding part of FIG. 6,

F i g. 8 by growing crystals with the aid of the device the F i g. 6 and 7 formed bodies.

F i g. 9 is a view of a crucible and a molding similar to FIG. 6, but here for the Crystal growth of a coiled, tubular hollow body with a circular cross-section,

FIG. 10 shows the crystal growth obtained with the aid of the apparatus of FIG. 9 formed body,

F i g. 11 is a sectional view shown in detail a device for growing crystals of a tabular body with two-axis curvature,

F i g. 12 is a sectional view in one section taken along line 12-12 of FIG. 11 laid cut,

Fig. 13 is a top plan view of the crystal growth tabular body having two-axis curvature used shaping part and

Figure 14 is a larger scale perspective view of the crystal grown with the aid of the apparatus of FIG. 11 to 13 educated Body.

Identical parts are provided with the same reference numbers in the drawings.

In Fig. 1 shows a furnace 2, consisting of a housing 4 and a heating device in FIG In the form of a high-frequency coil 6, which is fed from an adjustable hole frequency source (not shown) will. The coil can be moved all the way up or down on the housing and it Means are provided to them in an arbitrarily rooted way To hold the height. On the housing 4 are two ventilated lines 8 and 10 for the supply and discharge of a possibly to create an ent- fio speaking housing atmosphere required gas connected. The housing is partially closed against flow, and albeit graphically in the details is not shown. so the Gchaausc is of course constructed in such a way that the interior of the housing to the <> 5 Introducing a batch of the feed and / to attach an additional seed to one of the following still to be described pulling device is accessible.

Pie batch of ingredients is placed in a crucible 12 included (see Fig. 2) by a heat exchanger 14 and attached to the base of the foot Carrier 16 is held in a desired position. In connection with the furnace is a pulling device 18 provided, to which a pull rod 20 belongs, which is provided with a clamping device 22, which is used to hold a seed crystal 24 The pull rod 20 is passed through a suitable seal 26, so that the main part of the pulling head in FIG Way outside the oven. Although this is in the drawings in the structural details is not shown, it should be noted that the pulling device is designed so that the pull rod 20 both a rotary movement as well as a reciprocating translational movement can be issued. Pullers of this type are known in the art of crystal growth and their structural design therefore does not belong to the subject matter of the invention. The respective training of the pulling device is in Within the scope of the invention is irrelevant, provided that this device is only suitable, the desired rotary movement and translational movement. The pulling device is preferably constructed as this is shown in U.S. Patent 3,552,931. Here are individually controllable drive means for the Resolution of the rotary movement and the translational movement provided.

As in Fig. 2 is the heat exchanger Cylindrical design and has an iodine wall 28 which is firmly connected to the carrier 16. At the top At the end of the heat exchanger is open so that the crucible 12 can be introduced, which is in a relation is carried on the heat exchanger concentric arrangement of several pins 30. The crucible is there of a material that does not react with the melt and does not dissolve in it, d. H. so from one Resistant to the batch of molten feed material. Inside the crucible 12 is a generally with the reference numeral 32 designates a shaping part mounted, which includes a disk 34 which is attached to the crucible by a ring 36, and a Rod 38 attached to and supported by disk 34. The disc 34 serves at the same time also as a heat shield and to cover the crucible. The rod 38 consists of one of the molten ones Input wettable material. This rod has a rectangular cross-sectional shape and has a rectangular one Bore 40, the cross-sectional area of which is so large that it is suitable for the molten feed material, which is at 37 is shown, has no capillary action. In this connection it should be noted that the bore 40 does not have to extend the entire length of the rod, but must terminate above its lower end surface came so that a blind hole or cavity which extends from the upper end surface 44 downward. This latter area is flat, extends essentially in the horizontal direction uriii ends in the manner shown with sharp inside and outside of R <i, id cards. The rod 38 ends near the bottom of the crucible, but still above it, and has several small capillaries 46 on. which extend in the longitudinal direction of the wall and open into the upper and lower end surfaces of the rod. The capillaries are sized so that a column of melt due to the capillary action therein rises and the capillary in question fills up to the upper surface 44, as long as the capillaries with the lower

Immerse ren ends in the melt in the crucible. It should be noted that the height is up to which can rise a column of molten substance in a capillary, from the equation

h = 27cos ψΙarg

calculated, where h denotes the height of rise of the column, measured from the surface · of the melt in cm, T the surface tension in dynes / cm. ψ the contact angle, d the liquid density, r the inner radius of the capillary in cm and g the gravitational constant in cm / sec ² . For example, one can calculate that a column of molten aluminum oxide in a capillary provided in a molybdenum part corresponding to the rod 38 with a diameter of about 0.75 mm as a result of the capillary action up to a height of a little more than 11 cm above the surface of the The melt located in the crucible would increase.

It will now be described how with the help of the in F i g. 1 to 3 illustrated device made of a ceramic material, a practically monocrystalline tube is Herge, which characteristically has a rectangular cross-section and an axial twist. First, a crystal seed 24 (which has the same composition as the feed material) is clamped in the clamping device 22, the pull rod 20 being aligned in the axial direction with the rod 38 of the mold arrangement. If the crucible is then filled with a protective gas, the high-frequency coil 6 is put into operation to melt the charge. The capillaries are filled as a result of Kapillaranstiegswirkung with the molten mass from the Schmelzvorral 27 in the crucible and the power consumption of the high-frequency coil is such that the upper mold surface is brought to a temperature of 44 about 10 to 40 ⁰ C above the melting point of the seed crystal lies. The column of melt in each of the capillaries has a concave meniscus, the meniscus edge terminating at surface 44 at substantially the same level. It should be noted that the crystal nucleus can have any suitable shape and, for example, can be designed as a round or rectangular rod or tube. The crystal nucleus is preferably itself produced according to the method described, so that its cross-sectional shape corresponds to the formation of the surface 44, as shown in FIG. 4 is shown. The seed crystal is then guided down until it rests against surface 44 and is left in this position long enough for part of the seed to melt and form a liquid film 48 which extends over surface 44 and thus connects to the in the capillaries located melt produces. The temperature gradient in the longitudinal direction of the seed and the temperature of the surface 44 are factors which have an influence on how white the tube melts and how thick the film 48 is. In this context it should be noted that the tube acts as a heat sink and that the temperature of the tube at progressively higher points is influenced by the height of the coil 6 and the heat exchanger 14, but also by the power consumption of the coil. In practice, these parameters are chosen so that the initially formed film 48 has a thickness of about 0.1 mm. As soon as the film 48 establishes the connection with the melt located in the capillaries, the pulling device 18 is actuated to pull up the nucleus 24 as it moves away from the surface 44, without initially triggering a rotary movement. The pulling speed is set so that the film adhering to the tube as a result of the surface tension now crystallizes out at the interface of the solid tube and the liquid film due to a temperature drop occurring during pulling (it should be noted that this interface is essentially flat and extends parallel to surface 44). The drawing speed must also be such that the surface tension can cause the film to spread over the entire surface 44 (but this only applies if the initially formed film does not cover the entire surface). When the crystal nucleus moves away, crystal growth begins on all cables along the horizontal extent of the film, so that a tubular, monocrystalline extension or extension forms on the nucleus, this continuation being characterized by an inner and outer shape with a rectangular cross-section . The film used up by the crystal growth is replaced by new molten mass, which is supplied through the capillaries 46. As soon as the film 48 has completely covered the area 44 and has started to grow at all points along the film, the pulling device is actuated to rotate the pull rod at a precisely set angular speed without its upward movement being interrupted. The crystal nucleus now rotates with the pull rod, while the crystal growth continues at the same time. The continuous feed of solids

jo wax continues. so that a tube-like extension is formed. Because of the rotational movement that the seed crystal performs with respect to surface 44, and because of the adhesion of the film to the growing body due to surface tension are the successive ones However, increases according to the speed of rotation of the tension rod in an angular position offset against each other around the pull axis. The growth continues until the melt supply is sufficient is exhausted that a sufficient supply to the film 48 can no longer be maintained, or until the body has reached a desired length. In the latter case, the growth is stopped by the pulling speed is increased to such an extent that the crystal body becomes detached from the melt film.

It should be noted that the pulling speed and the film temperature in the course of crystal growth can be varied. However, the pulling speed and the temperature must not be that high not be so high that the tube is pulled away from the melt film. When growing crystals on a pipe body for example, alpha alumina becomes an initial axial pull rate of about 2.5 mm per minute is preferred, after which the speed is increased to about 5 mm per minute the film has spread enough to cover the entire end face of the process described above se heated mold assembly to cover. The Ziehge speed of the tube and the film temperature be The thickness of the film is right, which in turn determines the spread of the film. An increase the temperature of the surface 44 (and thus also the film temperature) and an increase in the drawing speed age have an effect in each case in a change in strength; of the film.

In Fig. 5, the shape of a substantially monocrystalline body 52 is shown, which is shown in the above be described manner by growing crystals by means of the apparatus of FIG. 2 and 3 was formed. The Filrr

strength is in adaptation to the growth rate of the growing crystal and the corresponding Speed of the axial feed movement of the pull rod is relatively low and is in the In most cases about 0.1 mm, so that for a growth of the body by about 1 cm, about ten volumes of the film are required. Trot /, this high degree of change in the melt film, however, the film thickness remains due to the constant supply of capillaries to the melt essentially constant.

The angular speed of the rotation of the body around the pulling axis must be limited so that in no shear is generated in the film and surface tension forces which prevent the wetting of the cause growing solids through the film and the adhesion at the interface, not impaired will.

The F i g. 6 and 7 show one for producing a rod body with one extending in the longitudinal direction Spiral hole (Fig. 8). In this arrangement ao, the shaping part 32 has a circular rod 38.4 with a circular trough 54 in the upper end surface 44 <4 and with a large number extending in the longitudinal direction extending bores 46Λ with capillary dimensions. The resulting from the crucible and the mold »5 standing arrangement of the F i g. 6 is received in the furnace housing in the heat exchanger, so that the The axis of the rod 38 with the axis of the tension rod 20 in Hucht lies. If a crystal nucleus is received in the jig 22, it forms on the surface 444 a film, and crystal growth is initiated in substantially the same manner as this above for the crystal growth of the rectangular tubular body of FIG. 5 has been described. If the film now spans the trough or recess 54 and there is a growth at all points in the horizontal Total expansion of the film, the growing body has a circular cross-section, which is characterized by a hole the size of which corresponds to the trough 54. When turning the growing Body, the successive increments then have the same cross-sectional shape, however the hole created by the absence of a melt film at the location of the well 54 in a Angular position is offset around the growth axis. The crystalline body formed in this way is in F> g. 8 shown. It is essentially a straight rod 58 with a cylindrical one Outer surface for which a bore 60 extending in the longitudinal direction is characteristic. the coaxial is coiled to the central axis of the rod.

In Fig. 9 there is shown an apparatus similar to that of FIGS. 6 is the same, but its rod 383 is circular Has trough or recess 62 which is formed centrally with respect to its film-bearing surface. the Melt is fed to this area through several capillaries 46 β. The ones from the crucible and from the mold existing device is built into the furnace in such a way that that the rod 38b is displaced sideways with respect to the pull rod 20, i.e. H. is arranged eccentrically. The seed crystal however, is arranged in the jig 22 so that its lower end is in the direction of escape of the rod 38ß lies. This can be achieved by the fact that the crystal nucleus in one to the axis of the tension rod 20 eccentric arrangement clamped in the jig. If you take with this arrangement in the manner described above before a crystal growth, wherein the growth nucleus 24/4 and the growing In this case, however, the crystal is guided around an axis (indicated by the broken line 66 in FIG. 9) which is offset from the axis of the rod 38ß, one obtains a body with the one shown in FIG. 10 shown shape. This body 69 of FIG. 10 is essentially tubular Hollow body with an elliptical cross-sectional shape, which is designed as a helix or helix.

Of course, the growing body can also with the help of the device of FIG Axis of the rod 38/4 eccentric axis are guided around. In this case it is so The body formed around a hollow helix is the same as that of FIG. 10, except that the through hole is now is not coaxial, d. H. in the cross-sectional view, this hollow helix is essentially the same Shape like the stick in FIG. 8th.

In the F i g. 11 to 14, a housing 70 is shown, which is designed so that an arm 72 can be supported therein which has a clamping device at one end 74 for holding a seed crystal 76 carries. In the support structure for arm 72 is a sleeve 78, which extends through and is secured in the wall of the furnace housing, as well as furthermore a shaft 80 which is received in the sleeve 78 in a rotatable arrangement. The arm 72 is on that inside end of the shaft 80 attached. The opposite end of the shaft 80 is fitted with a reversing electric motor 82 connected, the rigid with the aid of suitable (not shown) holding means is stored. The shaft 80 extends in the horizontal direction and is from the central axis of the Heat exchanger, the crucible and the mold existing and from a rod attached to the bottom of the housing 86 carried arrangement 84 offset to the side. The assembly 84 has a shape that has one of the shapes shown in FIG. 13 in engages disc 34 shown in the top view, which in turn carries a vertically arranged rod 38C, which has four longitudinal surfaces, one of which is a pair of surfaces (reference numerals 88 and 90) straight and is parallel, while the other two surfaces (92 and 94) are also arranged in parallel extension but one of these surfaces is concave and the other is convex. The bar 38C is also with a plurality of capillaries 46C which open into its upper end surface 44C. The arrangement 84 is so in Mounted on the stove with the rod 38C in the direction of escape of the seedling 76 is when the arm 72 is in a selected one shown in FIG. 11 position shown downwards is. If a melt film has been formed on surface 44C in the manner described above, see the arm 72 is guided upwards by actuation of the motor 82, one for crystal growth Appropriate heat management is provided. The growing crystal body takes a cross-section shape. that corresponds to the formation of the surface 44C Since the germ is also an arcuate movement because of the Schwenkbe movement of the arm 72 bahn describes how it is shown in Fig chene curve 96 is indicated, the successive crystal growth approaches form a continuation; which is curved according to the curved trajectory of the crystal nucleus. Fig. 14 shows the shape de formed crystal body 98. As the illustration ζ can be seen, this has in its cross-sectional shape a relatively wide concave or convex side wall before 100 and 102. which in their size · and shape de lateral marginal edges 92 and 94 correspond and they

409 548/3

: wipe two flat, parallel side surfaces 104 extend, which in turn correspond in size and shape to the side frames 88 and 90. The body is as well curved in the longitudinal direction. The body thus corresponds to a segment of a sphere.

An even more complicated shape is also possible. For example, a rotary movement of the seed crystal with the pulling motion of the device of FIG. 11 to 13 can be combined, making it is achieved that the crystal body on the one hand that of the F i g. 14 similar, but also in the direction of growth is coiled. Another possible modification is to change the direction of rotation of the Reverse the seedling once or several times or intermittently during the course of the crystal growth Provide rotational movement of the cultivation germ.

The following exemplary embodiment relates to the application of the method according to the invention with the aid the device of FIG. 1 to 4.

Embodiment

A molybdenum crucible with an inside diameter of about 38 mm, a wall thickness of about 5 mm and an inside depth of about 32 mm is placed in the furnace as shown in FIG. 1 and 2 is shown. In the crucible is a mold assembly generally shown in FIG. 2 and 3 introduced the structure shown. The external dimensions of the surface 44 of the rod 38 amount to 15.9 6.4 mm, the internal dimensions of the surface 44, ie the cross-sectional dimensions of the bore 40 are 12.7 3.2 mm. The length of the rod 38 is so dimensioned that its upper end protrudes about 1.5 mm above the crucible. The four capillaries each have a diameter of about 0.8 mm. The crucible is filled with practically pure, polycrystalline alpha-aluminum oxide, and a tubular body 24 made of monocrystalline alpha-aluminum oxide, which was also formed beforehand by crystal growth, is clamped in the clamping device 22. The tubular body 24 is straight and its cross section corresponds to the shape and size of the end face 44 of the rod 38. This tubular body is clamped in the device 22 in such a way that it is aligned with the tension rod 20 in the axial direction. The air is sucked out of the furnace housing 4 through the lines 8 and 10 and replaced by an argon atmosphere, a pressure of 1 atmosphere being set, which is maintained during the growth period. Thereafter, the high frequency coil 6 is energized and operated such that the alumina contained in the crucible is melted (the melting point of aluminum oxide is about 2050 ⁰ C) and that the surface is brought to a temperature of about 2O70 ° C 44th If the melt 27 has formed from the solid aluminum oxide, columns of this melt rise in the capillaries 46, which are thereby filled. After a sufficient dwell time to establish a temperature equilibrium, the pulling device is put into operation and operated so that the seed tube body comes into abutment against the upper surface 44 of the mold assembly, whereupon it remains in this position long enough for the lower end of the tube body melt and thereby form a film 48 which completely covers the surface 44 and provides the connection with the columns of the melt portions located in the capillaries. After about 60 seconds, the growth germ 24 is drawn off in the vertical direction at a rate of c ", va 2.5 to 5 mm per minute Film advances so that the growing crystal corresponds in its cross-sectional area and shape to the area 44. The surface tension of the film causes new portions of the melt to flow out of the capillaries, whereby the

ίο Volume of the film remains constant. Has pulling the If the tubular body lasted for about 2 minutes, the pulling device is used to initiate a rotary movement of the pull rod is actuated, and the rotary movement is carried out at an angular speed of about 2 ° per minute

> 5 minutes continued. The speed of the translational Pulling movement remains the same at about 5 mm per minute. Without prejudice to the rotational movement that the If the growth nucleation is carried out, the crystal growth stops in the entire extent of the film, but the

ao growing crystal as the growth proceeds a torsional deformation, so that it now appears twisted, as shown in FIG. 5 is shown. The growth is sustained without the speed of translational movement or now the pulling movement is changed until the crystalline extension on the seedling reaches the desired length has increased, whereupon the speed of the translational pulling movement abruptly to about 25 mm is increased per minute, so that the growing body is now detached from the film 48. Then one lets cool the oven and the seed 24 is removed from the jig 22 again. It shows that the extension formed on the tubular body has a cross-sectional configuration that corresponds to the shape corresponds to the end face 44 of the mold assembly, the wall thickness being approximately 1.5 mm. aside from that the extension is characterized by a spiral twist. The crystal grown is essential monocrystalline and represents a crystallographic extension of the crystal lattice of the seed tube body 24 represents.

It should be emphasized that if the working temperature (which in this context is to be understood as the average temperature of the film 48) is kept constant at a value close to but still slightly above the melting point of the material to be grown, the drawing speed can be varied within certain limits (which is from the respective working temperature), without this resulting in a noticeable change in cross-section of the grown crystal. Accordingly, in keeping constant the pulling speed and the working temperature may be varied considerably (based on the melting point of the alumina, for example, as 15 to 30 ° no less) without the cross-section of the grown crystal would substantially change hierbe. ¹

Essentially the same working conditions as in the above embodiment can also be used

will hold if with the devices of FIG. 6th 7 and 9 and 11 to 13 formed by crystal growth practically table monocrystalline aluminum oxide bodies and if one uses the procedural methods described above for the crystal Cultivation of bodies of the in F i g. 8, 10 and 14 shown th type were described. Also bodies with others Cross-sectional shape, such as solid rods or tubular bodies with ash-edged, square or square tubes

triangular shape. Rods with several, located in the Longitudinally extending bores, etc., can be formed with the rotational deformation according to the invention will. If the rod 38 of FIG. 2 and 3 by a rod with two or more round ones Axle bores replaced in place of bore 40. «> can produce a shallow crystal by growing crystals using the procedure of the above embodiment Rod can be formed from monocrystalline aluminum oxide, which has two or more axis bores.

A major advantage of the invention is that it also applies to crystalline substances other than just aluminum oxide Can apply. The applicability of the invention is not limited to the same melting substances and also extends to the crystal growth of substances that are in a cubic, solidify rhombohedral, hexagonal or tetragonal crystal structure, so inter alia. Ruby, spinel, beryllium oxide, Barium titanate, yttrium aluminum garnet, lithium niobate. Uthium fluoride and calcium fluoride. For this an- ao whose substances the procedure is essentially the same as described above for alpha alumina, only that in this case because of the different melting points and because of the different, With regard to the material to be grown, the crystal nuclei selected have different working temperatures required are. In addition, it may also prove necessary to adjust certain of the device make small changes, for example to the effect that for the crucible and for the shape depending on the nature of the reaction and the respective melting point of the melting material, other materials must be chosen.

From Laue back-radiation diagrams, which were recorded in the crystal growth carried out in accordance with the invention, it can be seen that the crystal growth usually includes one or two crystals, sometimes three or four crystals, which grow together and in the longitudinal direction through a grain size / e are separated from each other by a small angle (mostly below 4 ^C in the C-direction). To distinguish it from a polycrystalline crystal growth, this type of growth can be referred to as "essentially monocrystalline", with the proviso that the crystal body can consist of a single crystal or of two or more crystals, for example a bicrystal or tricrystalline, which grow together in the longitudinal direction, but are separated from one another by a grain boundary with a relatively small angle (ie less than about 4 °).

The term "end face" is understood to mean the effective film-bearing face of the shaping part; the term "capillary" is intended to include passages of very different cross-sectional shapes and thus include, for example, rectangular bores or annular spaces.

The claimed method permits the growth of essentially monocrystalline bodies Complicated shaping for different purposes, for example the manufacture of ceramic Bourdon tubes as used in the manufacture of pressure transducers for high temperature purposes be, and the arched body with a wing-shaped cross-section, which when executed from a high temperature-resistant material suitable as a turbine blade.

For this purpose 3 sheets of drawings

Claims (1)

Godparents—, ,. Method for drawing a crystalline body of predetermined cross-section from a melt tube using a shaping device which has at least one capillary passage for supplying the melt from a supply melt located at the lower end of the capillaries _to an upper horizontal end surface of the shaping part, the Endobeiflje limited by downwardly extending edge surfaces and is essentially the same as the defined cross-sectional area. so that it is located up to the edges of the melting point characterized in that during of pulling the crystalline body is rotated so fast around an axis that by offset successive Growth a twisted body arises. 2. The method according to claim 1, characterized in that the upper horizontal Endober pool a continuous inner edge rises and the crystalline body around eme to the end surface vertical axis is rotated. 3. The method according to claim 2, characterized in that that the crystalline body is peeled off from the melt film in a vertical direction. 4. The method according to claim 3, characterized in that the crystalline body along the vertical Axis of rotation is drawn. 5. The method according to claim 3, characterized. that the kiistallm- · body in a vertical Direction along one of the vertical axes of redness laterally offset axis is pulled. this known method is the shape Kit «» "" W ^ simplest germination training than ^ J '" ⁿ _r ^e " j5 £ weeping diameter. The wax π ^ ω »* ^ _{a crystal | wjm} turn ^ "Äfitsfilm between the growing- au «** ™ J ^ _{r the end of} the shaping part. the Koiper ^ uro ^ ^ _constantly ^{where d} '£ ⁵ ™ ^ J provided _the forming part ^ ^ he more m "^ th melting stock erKap. tares ^ ™ ^ corresponding pulling, 5 whole becomesUurcn ι _an ^ _axed body and weaknesses for α, of _{the F} , _ussi f ^^ £ J * Scben? dtf the film thanks to the ££ * '^^ surface tension over the total effect of the ^u ° _ebun £ _{stei! i} , ..;, "" whose around ^l . ^e '' _H | _{inie or} lines spreads. This marginal edge fangsrandl e or 1 _{dje intersection of the} dzw edge wera itenfläche _Se (n) of the FormEndflach ™ t of the _Q-angle, identical _{under these} gebungsteils gebuae '■ _beautiful. is under ^Fa ? _h , t _m 7def contact angle of the liquid ™ ^^ tg »g of the ^„ » _{h the} f.Ims chosen so that » _{edge edge} resp. Fluss.gke.t ^{a Η} ^ ~ _{ΗίηαεΓΐ} . _As cutting angle edges of the end ^surface J _n ^ _{surface (s} ) of the shaping between shear1 end ^ and f ^^^. ' _wave , _provided . ^S _for legal reasons. The crystal body of ^! «""F" ^ those of the edge channels. . given ^to grow in P ^{ass "n} S ^a" f ^^ ί "Form This ausb.ldung the Fo m ^ nd» ^e f | _krjstalliner ^Ra " ^{d came} 7. The method according to claim 1, characterized in that, used in the molding part w.rd. its upper horizontal end surface e.ne circular shape having outer edge edge. 8. The method according to claim!, Characterized that the crystalline body is rotated around a honzontal axis. 50 SÄ according to the Q " ^e _b ™ _uchten procedure. that ^^^^ nSe ^ dobtvnichc as one de the enamel. ^m ^ f ^^ " _{e acts (i.e.} , we. testing" therme warmth q |, ^ _6n that ⁱⁿ iJ ^ 5a _tu CofH aSst. and that the aches Τ-Ρ "" _η ^ _in \ ^U _{melting stock ni} ch is beeSßt and can be maintained at an average temperature of bef.ndl.chen from the average temperature in the Schmelzgefaß l temperature de
Melt is different. melt the body around ™ * ™ * ™ £ ^ growth to an upper horizontal end surface of the molded part, with the end surface through ^ ^rsct ^ .. ^d _n ^U [ ^C _r ' ⁿ _n ^al ^ _n ^OlgCnÜeS before by downwardly extending K.ntenflächcn 60 twisted K pe _{n, TCHT ri} _ limited and substantially the predetermined trf.ndung The g 'is ^{in the} tattet, _F Cross-sectional area is the same. so that there are stable bodies ^ _to chaffeη b P ^ mmMm 3 591 348. axis of rotation,