US3791188A

US3791188A - Method of die-forming parts with improved grain structure

Info

Publication number: US3791188A
Application number: US00192289A
Authority: US
Inventors: E Deussen
Original assignee: Individual
Current assignee: Individual
Priority date: 1971-10-26
Filing date: 1971-10-26
Publication date: 1974-02-12
Anticipated expiration: 1991-02-12

Abstract

A method of die-forming parts so that, in their final shape, they have a substantially continuous grain structure, whereby a cylindrical blank is shaped into a spherical part by drawing the grain line ends together in two polar areas, and the spherical part is reshaped into a ring of final dimensions without breaking any of the grain lines.

Description

PATENIEDFEH 12 19M 3,791,188

SHEET 1 BF 2 INVENTOR:

IPATENTEDIFEBIZ I574 37 1 sum 2 0F 2 INVENTORI E'WHL. DEUSSEN BY: W AGE T BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to methods of dieforming metal parts and in particular to a method of die-forming metal parts in such a way that the grain lines in the final part remain uninterrupted, the part being shaped in a non-cutting cold-forming method to final dimensions without requiring any subsequent machining on a lathe, planer, or mill, and without requiring any subsequent heat treatment.

2. Description of the Prior Art Normally, machine parts which receive their form through forging or through material-removing machining operations have a grain structure which is interrupted in many places. Such an interrupted grain structure can represent major problems in some cases of machine parts, the interruptions leading to hardening cracks, fatigue fractures and the like. It would be possible to avoid such shortcomings if a solution can be found to produce these machine parts'in such a way that their grain lines remain unbroken. Of course, a prerequisite for such a condition is that the blank piece, too, has an unbroken fiber structure.

The only shape which can be produced with a substantially unbroken grain structure is a sphere. It is known to obtain such a structure in the production of spheres, by inserting a cylindrical blank into the forging dye in such a manner that the grain direction of the which it is to be shaped, and that the grain orientation of the blank is perpendicular to the direction of compression. Using these particular dimensions for the blank and observing the perpendicular grain orientation, one obtains a spherical part which has a practically unbroken fiber structure, rendering it superior to other spherical parts. In thisforming method, the grain v line ends are virtually drawn together in a single point,

blank extends in the direction of compression. However, due to the fact that the grain lines in the end faces of the blank are broken, the forged sphere will also have broken, grain lines in one of its axes and because the blank is usually of a somewhat greater volume than the volume of the fully closed forging die, the finished sphere will have a small so-called equator" which has to be removed by grinding. Such a grinding operation, however, results in an interruption of the grain structure, leading to situations where, under heavy shock load conditions, the balls chip on their surface, or split into two halves.

SUMMARY OF THE INVENTION It is a primary objective of the present invention to suggest a method of die-forming machine parts where the grain structure remains unbroken and where the method is easy to perform and requires no additional work operations.

Inorder to attain this objective, the invention proposes a method where the blank is initially formed to a spherical shape with substantially uninterrupted grain lines, whereupon the spherical intermediate part is reshaped into the desired end shape without interrupting the substantially continuous grain structure. It should be understood that the spherical intermediate part can also be used as an end product, in cases where it is desired that the end product is a sphere. The purpose of the method of the invention is in each case to obtain parts whose improved grain structure gives them superior resistance characteristics over similar parts whose grain structure is broken.

In a further development of the invention, it is suggested that the blank used to produce the spherical intermediate part has the same volume as the sphere into or at least into a very small area, so that the resistance of the sphere is not impaired. The spheres obtained with this new forming method are definitely superior to those where a grinding operation is necessary to produce the final form as'in the case mentioned further above.

A further suggestion of the invention provides that the spherical'intermediate part is inserted into a forging die which has a recessed forging punch and where the sphere is reshaped into a sleeve or a ring or any similar final shape. Again, the grain structure remains unbroken after this reshaping operation, so that the sleeve or ring obtained has exceptional resistance characteristics and therefore is not subject to prematrue aging or fatigue failure.

BRIEF DESCRIPTION OF THE DRAWINGS Further special features and advantages of the invention will become apparent from the description following below, when taken together with the accompanying drawings which illustrate, by way of examples, several steps embodying the method of the invention, represented in the various figures as follows:

FIG. 1 shows the forging die with a blank inserted therein;

FIG. 2 shows a spherical part as obtained by using the tool shown in FIG. 1;

FIG. 3 shows an opened forging die in which an intermediate spherical part is to be reshaped into a sleeve;

FIG. 4 shows a sleeve such as may be obtained by using the tool of FIG. 3;

FIG. 5 shows an open ring as an alternate end product obtainable by using the tool of FIG. 3;

FIG. 6 shows another opened forging die where an intermediate spherical part is to be reshaped into a ring of different cross-section; and

FIG. 7 shows the tool of FIG. 6 in its closed position.

DESCRIPTION OF THE PREFERRED EMBODIMENTS In order to produce the sphere l of FIG. 2, a cylindrical blank 2 is inserted into the forming die of FIG. 1 and so oriented between the die parts 4 and 5 that the grain lines 3 of the blank are oriented perpendicularly to the direction of compression. The volume of the blank is the same as the volume of the space contained between the closed die parts 4 and '5. The sphere 1 (FIG. 2) obtained in the first forming operation has no equator and the grain lines 3 are drawn together into very small areas 6 and 7 at opposite poles of the sphere 1 so as to produce a body of substantially continuous grain structure.

As is shown in FIG. 3, the sphere 1 can be reshaped in a forging die 8 by means of a punch 9 which squeezes the intermediate sphere into the final shape of either a cap sleeve 10 with a closed end portion 11 (FIG. 4) or a ring 12 (FIG. 5). The lines 3 in FIGS. 4 and 5 indicate the preserved continuity of the grain structure of the final parts.

In FIGS. 6 and 7 are shown the different methods and steps for reshaping the intermediate sphere 1 into a ring 19, by using a forging die consisting of two

die parts

13 and 14 which carry in opposite alignment two

pressure spheres

15 and 16. The intermediate sphere l itself is held in position between two

brackets

17 and 18 which, as the die deforms the sphere l by closing, are retracted outside the die stroke. The sphere l is so oriented in the forging die of FIG. 6 that the two poles 6 and 7 on which the grain lines 3 meet are aligned with the compression axis of the die. As can be seen in FIG. 7, the reshaped part has its previous poles 6 and 7 compressed into a narrow web 20 between the pressure spheres l and 16 so that, for all practical purposes, all the grain lines inside the reshaped part 19 are continuous and unbroken. This ring is subsequently reshaped into its final form in a further forging operation, the latter not being a part of this invention.

It should be understood that, whenever it is desired that the sleeve or the rings 12 have final dimensions as required by the drawing, it is a necessary prerequisite that the intermediate spherical part have exactly the same volume as the final part. Following the forging operation described above no additional machining is necessary, except for possible surface grinding or polishing operations. Furthermore, no subsequent heat treatment is necessary, as the required degree of hardness is obtainable by using this constantvolume forming method.

I claim:

1. A method of die-forming parts so that, in their final shape, they have a substantially continuous grain structure, comprising the steps of:

sizing a cylindrical blank with parallel, longitudinal grain lines to a volume corresponding to that of the final part desired;

inserting the blank into a forging die having two hemispherical die halves in such a way that the direction of the grain lines is perpendicular to the direction of die closing; and

shaping the blank into a spherical part by closing the die, thereby joining the ends of the grain lines of the blank in two narrow polar areas of the sphere. 2. A die-forming method as defined in claim 1, further comprising the steps of:

introducing the spherical part into a ring-forming die;

and reshaping the spherical part into a ring by closing the ring-forming die in such a manner that the center portion of the sphere is displaced radially outwardly to form the ring without interrupting any grain lines in the ring. 3. A die-forming method as defined in claim 2, wherein;

the ring-forming die has a cylindrical bottom part and a cylindrical recessed punch concentrically aligned with the latter; and the step of reshaping involves the displacement of the sphere volume into the shape of a cylindrical sleeve with a closed end portion across the lower sleeve face. 4. A die-forming method as defined in claim 1, further comprising the steps of:

introducing the sperical part into a ring-forming die which includes two pressure spheres oppositely aligned in the mating die parts, and holding means for positioning the spherical part in axial alignment between the closing pressure spheres; orienting the spherical part so that the grain junction poles are in alignment with the movement axis of the pressure spheres; and reshaping the spherical part by closing the ringforming die until the two pressure spheres are in near contact with one another and the previously separate grain junction poles are substantially united in a narrow compressed web portion in the center of the ring. 5. A die-forming method as defined in claim 4, wherein;

the ring-forming die has a closed volume which is equal to the volume of the spherical part so as to produce a ring part without a peripheral bead.

Claims

1. A method of die-forming parts so that, in their final shape, they have a substantially continuous grain structure, comprising the steps of: sizing a cylindrical blank with parallel, longitudinal grain lines to a volume corresponding to that of the final part desired; inserting the blank into a forging die having two hemispherical die halves in such a way that the direction of the grain lines is perpendicular to the direction of die closing; and shaping the blank into a spherical part by closing the die, thereby joining the ends of the grain lines of the blank in two narrow polar areas of the sphere.

2. A die-forming method as defined in claim 1, further comprising the steps of: introducing the spherical part into a ring-forming die; and reshaping the spherical part into a ring by closing the ring-forming die in such a manner that the center portion of the sphere is displaced radially outwardly to form the ring without interrupting any grain lines in the ring.

3. A die-forming method as defined in claim 2, wherein; the ring-forming die has a cylindrical bottom part and a cylindrical recessed punch concentrically aligned with the latter; and the step of reshaping involves the displacement of the sphere volume into the shape of a cylindrical sleeve with a closed end portion across the lower sleeve face.

4. A die-forming method as defined in claim 1, further comprising the steps of: introducing the sperical part into a ring-forming die which includes two pressure spheres oppositely aligned in the mating die parts, and holding means for positioning the spherical part in axial alignment between the closing pressure spheres; orienting the spherical part so that the grain junction poles are in alignment with the movement axis of the pressure spheres; and reshaping the spherical part by closing the ring-forming die until the two pressure spheres are in near contact with one another and the previously separate grain junction poles are substantially united in a narrow compressed web portion in the center of the ring.

5. A die-forming method as defined in claim 4, wherein; the ring-forming die has a closed volume which is equal to the volume of the spherical part so as to produce a ring part without a peripheral bead.