US2752651A

US2752651A - Centrifugal casting molds

Info

Publication number: US2752651A
Application number: US303882A
Authority: US
Inventors: Seeba Johann; Biefang Peter; Simonis Alfred
Original assignee: Eisenwerke Gelsenkirchen AG
Current assignee: Eisenwerke Gelsenkirchen AG
Priority date: 1951-08-13
Filing date: 1952-08-12
Publication date: 1956-07-03
Anticipated expiration: 1973-07-03

Description

4 Sheets-Sheet 1 Filed Aug. 12, 1952 V/TV J. SEEBA El AL July 3, 1956 ed Aug. 12, 1952 Inventors: 8A, ER EIEFAHGP July 3, 1956 CENTRIFUGAL CASTING MOLDS g 4 Inventory? J'oHAnrI SEEBAI PETER BIEHVYG- A'Ho ALFRED .Srmoms J. SEEBA ETAL 2,752,651 I July 3, 1956 J. SEEBA EIAL CENTRIFUGAL CASTING MOLDS 4 Sheets-Sheet 4 Filed Aug. 12, 1952 0am SEE MP ALFRED BY.

2,752,651 CENTRIFUGAL CASTING MOLDS Johann Seeba,

Gelsenkirchen, Gelseukirchen, many Application August 12, 1952, Serial No. 303,882 Claims priority, application Germany August 13, 1951 11 Claims. (Cl. 22-1135) Peter Biefang, and Alfred imonis, Germany, assignors to Eisenwerke Aktiengesellschaft, Gelsenkirchen, Ger= stresses on the mold wal However, the above mentioned grooves have serious disadvantages. Thus, when the molded article is re- Moreover, with molds having an inner surface provided with axially and circnmferentially extending grooves, the axially extending grooves gradually become wider and the circumferentially extending grooves gradually close shape for a long period of time and will not easily become closed up.

Yet another object of the present invention is to pro a mold grooves which will the inner mold surface.

silicon powder.

A still further object of the present invention is to provide on the inner surface of a centrifugal mold a patto an axis normal 2 tern of grooves which form between themselves areas capable of becoming automatically grouped in different ways to best suit the particular molding conditions.

An additional object of the present invention is to provide a process for easily and quickly forming grooves of the above type on the interior of the mold.

A still additional object of the present invention is to prevent the formation of cracks at those parts of a mold which are subjected to relatively high stresses.

to the longitudinal axis, these grooves preferably making an angle of between 40 and 50 with these axes. In a preferred form grooves are arranged in a honeycomb pattern.

The novel features which are considered as characteristic for the invention are set forth in particular in the appended claims. The invention itself, however, both tion;

Fig. 2 is a fragmentary, sectional view of inner surface of the mold of Fig. l, larged scale the grooves therein;

Fig. 3 is a fragmentary, developed view on an enlarged scale of the inner mold surface of a mold construction in accordance with the present invention;

Fig. 4 is a fragmentary, developed view on an enlarged scale of the inner mold surface of another mold constructed in accordance with the present invention;

Fig. 5 is a fragmentary, longitudinal sectional View through a mold of relatively small size constructed in accordance with the present invention; and

ig. 6 is a fragmentary, longitudinal sectional view through a mold of relatively large size constructed in accordance with the present invention.

a part of the showing on an ennormal thereto and prefer and 50 with these Patented July 3, 1956 of the invention, the' finer than the grooves 3. Although in the particular example shown the grooves 4 divide the area between the grooves 3 into triangles, it is also possible to provide additional grooves, similar to grooves 4, dividing these areas into four cornered areas or into haphazard areas. Instead, of a six cornered honeycomb arrangement as shown in Fig. 3, it is possible to use patterns having areas formed with a different number of corners, such as five or eight cornered honeycomb patterns, and it is not essential that all the sides of the areas formed by the honeycombpattern of grooves be straight. The grooves 4 cooperate with the grooves 3 to provide an inner mold surface capable of holding a powder in a uniformly distributed manner. The centers of the areas formed by grooves 3 are substantially. equidistant from the corners and sides of these areas so that a non-uniform stress in the inner mold surface is avoided to a great extent.

In Fig. 4 there is shown on an enlarged scale a developed view of the inner surface of a further embodiment of a mold constructed in accordance with the present invention. In this embodiment of the invention, three sets of parallel, equally spaced grooves intersect each other toform areas 5 in the shape of equilateral triangles, and, as is apparent from Fig. 4, none of the grooves are parallel to the longitudinal axis 1 of the mold. During operation of a mold constructed in accordance with Fig. 5, thehigh temperature acting on the inner mold surface will cause the latter to expand as a result of the stresses therein, and during such expansion, the triangular areas 5 will automatically group themselves to produce honeycombed six cornered patterns, such as 6, 7 and 8 of Fig. 4, depending upon the particular stresses produced in the mold during operation thereof. These various honey comb. patterns Will be best suited for the particular conditions within the interior of the mold. It is also possible for the triangular areas 5 to group themselves together to form an irregular honeycomb pattern. This particular form of the invention is particularly advantageous because it is very simple to form the areas 5 on the inner mold surface.

With conventional centrifugal molds, the larger stresses take place in the cylindrical part of the mold. However, it has been found that the molds constructed in accordance with the present invention, where the grooves are inclined to the longitudinal axis of the mold and an axis normal thereto, the cylindrical part of the mold remains undamaged for a long period of time, and the first cracks start to appear in those parts of the mold which are located next to the ends of the uniform cylindrical part.

In order to avoid the formation of cracks in these parts of. the mold which are subject to relatively high stresses, the constructions of Figs. 5 and 6 are provided. In these figures there are shown portions of two molds having formed therein

grooves

9 and 10 of the same construction as was described above in connectionwith Fig. 1. It has been demonstrated by experience that the above-described centrifugal casting molds of relatively small size, i. e. below 200-250 mm. diameter, tend to form predominantly longitudinally extending cracks in the highly stressed regions thereof, and the above-described molds of relatively large size, i. e. over 250-300 mm. diameter, tend to produce predominantly circumferential cracks in their highly stressed regions. mold, of Fig. 5: represents a mold of a relatively small size and is formed in its region of extremely high stresses with the longitudinal grooves 11, while the mold of Fig. 6 represents a mold of relatively large size and is formed in its. highly stressed region with the circumferential grooves 12.

Where the grooves on its inner surface of the mold, such as the

grooves

9 and 10, have a depth of approximately 0.2 mm., experience hasv shown that it is best to make the

grooves

11 or 12 with a depth of approximately 0.5 mm. Also, where these grooves, such as grooves9 and 10., are located. apart from eachother by a: distance;

The

of l-2 mm, as was described above, experience has shown that it is best to locate the grooves 11 or the grooves 12 apart from each other, by a distance of from 2 mm. to 10 mm. Thus, where the grooves 9 or the grooves it are located apart from each other by a distance of 1.5 mm, the grooves 11 or the grooves 12 would be located apart from each other by a distance of approximately 6 mm.

Centrifugal casting molds of the type described above may have their inner surfaces formed with the abovedescribed grooves in a number of different ways. For example, it is possible to turn the grooves into the inner surface of the mold with a machine tool. One of the most preferred ways of forming the indentations, on the inner surface of the mold is to use a knurled wheel having on its outer surface sets of ridges which intersect each other and are inclined to the longitudinal and transverse axes of the knurled wheel. This knurled wheel is pressed against the interior surface of the mold, and the mold and knurled Wheel are moved with respect to each other so that the knurled wheel moves with respect to the mold circumferentially about the inner surface thereof and moves axially with respect to the same, at the proper rate, so that the desired indentations are in this Way formed on the interior of the mold. The advantages resulting from this process of forming the grooves on the interior of the mold are not only in. its simplicity but also in the fact that the material of the mold is compressed by the knurled wheel so as to greatly strengthen the mold.

It will be understood that each of the elements, described above, or two or more together, may also find a useful application in other types of centrifugal molds differing from the types described above.

While the invention has been illustrated and described as embodied in centrifugal molds having on their inner surfaces grooves which are inclined to the longitudinal and transverse axes of the molds, it is not intended. to be limited to the details shown, since various modifications and structural changes may be made Wtihout departing in any way from the spirit of the present invention.

Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can by applying current knowledge readily adapt it for various applications without omitting features that, from the standpoint of prior art, fairly constitute essential characteristics of the generic or specific aspects of this invention. and, therefore, such adaptations should and are intended to be comprehended within the meaning and range of equivalence of the following claims.

What is claimed as new and desired to be secured by Letters Patent is:

1. An elongated, tubular, centrifugal casting mold having an. inner surface formed with a plurality of elongated, intersecting grooves whichare inclined to the longitudinal axis of the mold and an axis normal to the longitudinal axis and make an angle of between 40 and 50 with at least one of said axes.

2. An elongated, tubular, centrifugal casting mold having an inner surface formedwith a pluality of elongated, intersecting grooves which are inclined to the longitudinal axis of, the mold and an axis normal to the longitudinal axis and make an angle of between 40" and 50"- with both of said axes.

3. An elongated, tubular, centrifugal casting mold having an inner surface formed with a plurality ofgrooves arranged in a honeycomb pattern and all being inclined to the longitudinal axis of the mold.

4. An elongated, tubular, centrifugal casting mold having an inner surface formed with a plurality of grooves arranged in a inclined to the longitudinal axis of the mold, said inner surface. having the portions thereof located between said grooves formed with additional grooves finer than said' honeycomb pattern and all being first-mentioned grooves and dividing said portions into polygonal areas.

5. An elongated, tubular, centrifugal casting mold formed on its inner surface with three sets of parallel grooves, said sets intersecting each other and all pairs of adjacent grooves of said three sets of grooves being located apart from each other by equal distances, and said grooves forming between themselves areas on the inner surface of the mold having the shape of equilateral triangles, all of said grooves being inclined to the longitudinal axis of the mold and an axis normal to said longitudinal axis.

6. A centrifugal casting mold as defined in claim 5 and wherein all of said grooves are of the same depth.

7. A centrifugal casting mold as defined in claim 5 and wherein each pair of adjacent grooves of said three sets of grooves are located apart from each other by a distance of approximately 1.5 mm.

8. An elongated, tubular, centrifugal casting mold having a diameter of less than 250 mm., being formed on its inner surface with intersecting sets of grooves all of which are inclined to the longitudinal and axis of said mold and an axis normal to said longitudinal axis, and being formed at parts thereof which are subjected to relatively great stresses with an additional set of grooves substantially parallel to the longitudinal axis of said mold.

9. An elongated, tubular, centrifugal casting mold having a diameter of more than 250 mm., being formed on its inner surface with intersecting sets of grooves all of which are inclined to the longitudinal axis of said mold and an axis normal to said longitudinal axis, and being formed at parts thereof which are subjected to relatively great stresses with an additional set of circumferential grooves located about the longitudinal axis of said mold.

10. A centrifugal casting mold as defined in claim 8 and wherein said additional set of grooves are approximately 0.5 mm. deeper than said intersecting sets of grooves and located apart from each other by a distance of from 2 to 10 mm.

11. A centrifugal casting mold as defined in claim 9 and wherein said additional set of grooves are approximately 0.5 mm. deeper than said intersecting sets of grooves and located apart from each other by a distance of from 2 to 10 mm.

References Cited in the file of this patent UNITED STATES PATENTS OTHER REFERENCES Catalog Reed Knurls, by Reed Small Tool Works, Worcester, Mass., Catalog No. 62, Jan. 1, 1944,

pages

3 and 9, item 20 (AM, AF or WM).

Claims

1. AN ELONGATED, TUBULAR, CENTRIFUGAL CASTING MOLD HAVING AN INNER SURFACE FORMED WITH A PLURALITY OF ELONGATED, INTERSECTING GROOVES WHICH ARE INCLINED TO THE LONGITUDINAL AXIS OF THE MOLD AND AN AXIS NORMAL TO THE LONGITUDINAL AXIS AND MAKE AN ANGLE OF BETWEEN 40* AND 50* WITH AT LEAST ONE OF SAID AXES.