Patent Publication Number: US-7895873-B1

Title: Method and system for simultaneously forging two parts

Description:
BACKGROUND 
     Previously it was known for forging two separate parts to use two separate forging dies in two separate forging presses, or in a common forging press. A separate die for each part was employed with each die having a forging cavity receiving a billet in order to manufacture the two separate parts. It was also known to have a common die in a single forging press for forging two separate parts simultaneously in the common die, but with the respective cavities for the respective parts being side-by-side. 
     SUMMARY 
     It is an object to provide a new improved type of forging die for use in a single press for simultaneously forging two separate parts. 
     In a method or system for simultaneously forging parts, a forging die is provided with a bottom part and a top part, the forging die having a first forging cavity, a second forging cavity surrounding the first forging cavity, and a connecting opening between the first forging cavity and the second forging cavity. A billet is placed in a lower portion of at least one of the first forging cavity, the second forging cavity, and the connecting opening. Then, with a forging press, the forging die is closed so that the die bottom part and die upper part approach one another to cause material of the billet to spread throughout the first forging cavity, the connecting opening and the second forging cavity. The forging die is opened and a resulting unified forging part is removed formed of a first forging part, a second forging part surrounding the first forging part, and a connecting region. The first forging part and the second forging part are then separated at the connecting region. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a cross-sectional view of a forging system for simultaneously forging two parts in a common cavity resulting in an inner forging part and an outer forging part (part-in-part) surrounding the inner forging part; 
         FIG. 2  is a side view of a resulting inner forging part connected to the outer forging part after removal from the forging die of  FIG. 1 ; 
         FIG. 3  is a perspective view of the inner forging part and the outer forging part shown in  FIG. 2 ; and 
         FIG. 4  is an exploded view of the inner forging part after separation from the outer forging part. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     For purposes of promoting an understanding of the principles of the invention, reference will now be made to the preferred embodiment/best mode illustrated in the drawings and specific language will be used to describe the same. It will nevertheless be understood that no limitation of the scope of the invention is thereby intended, and such alterations and further modifications in the illustrated device and such further applications of the principles of the invention as illustrated as would normally occur to one skilled in the art to which the invention relates are included. 
       FIG. 1  is a cross-sectional view of a forging system generally illustrated at  10  employing a forging die  11  having a bottom die part  11 A and a top die part  11 B. The forging die  11  is mounted in a forging press  8  having a bottom press bed  8 A and a movable press ram  8 B. 
     Between the bottom die part  11 A and top die part  11 B a common forging cavity  9  for both an inner forging part and an outer forging part surrounding the inner forging part is located. A top part of the forging cavity  9  is provided in the top die part  11 B and a lower part of the forging cavity resides in the bottom die part  11 A. 
     The cavity  9  shown in  FIG. 1  is particularly designed for illustrating in this exemplary embodiment the manufacture of a pinion gear as the inner forging part and a cooperating ring gear as the outer forging part. The pinion gear and the ring gear are merely exemplary, and many other types of parts may be simultaneously forged with the forging process. 
     In  FIG. 1  the pinion gear cavity  12  (inner forging cavity) is formed by a shaft portion  12 B and a pinion gear portion  12 A having a centering projection  12 C. The ring gear cavity  13  (outer forging cavity) has a ring gear portion  13 A and a circumferential narrow connecting opening  13 B connecting the inner forging cavity  12  for the pinion gear with the outer forging cavity  13  for the ring gear. As also shown in  FIG. 1 , the shaft portion  12 B in the bottom die part  11 A is many times deeper than a lower portion of the outer forging cavity  13  in the bottom die part  11 A. 
     A circumferential excess material flow gap  14 A surrounds the ring gear cavity portion  13 A leading to a widened circumferential excess material exit region  15 A. 
     An ejector pin  16  is provided in the bottom die portion  11 A in an aperture  7  in the bottom of the bottom die portion  11 A. 
     A hot malleable billet of the material to be used in the forging (such as metal or other materials) may be a hot rolled bar stock that is cut into a short piece of a desired size. Alternatively, the hot malleable billet may be formed by other earlier forging operations of many different types. This billet is placed in the forging cavity  9  when the press ram  8 B opens the die (upper position). As the press ram  8 B descends, the heated malleable billet is compressed and flows throughout the cavity  9 , including in the narrow connecting opening  13 B, in the inner and outer cavities  12  and  13 , and through the excess material flow gap  14 A into the exit region  15 A. Thus the same billet is used for forging the inner forging part  18  (pinion gear  18 A with shaft  18 B) and the outer forging part  19  (ring gear). The two parts prior to separation as illustrated in  FIG. 2  are joined by a circumferential connecting web or region  19 C as a unified forging part  17 . A centering dimple  18 C is provided at the top of the pinion gear  18 A connecting to the lower pinion gear shaft  18 B. 
     The billet may be placed in the inner cavity  12 , outer cavity  13 , in the connecting opening  13 B, or any combination. 
       FIG. 3  shows a perspective view of the inner forging part  18  and the outer forging part  19  of the unified forging part  17  prior to separation creating a “part-in-part” configuration. 
       FIG. 4  shows the separation of the inner forging part  18  and outer forging part  19  by cutting away the inner flash ring  19 C (circumferential connecting web), which constituted scrap. Similarly an outer flash ring  19 B formed of excess material is cut away, which also constitutes scrap. Additional processing such as heat treating, cutting the gear teeth, etc. may now be performed depending on the type of part involved. 
     Although metal is described for the heated and malleable forging ingot, other types of material may also be employed as desired depending on the type of forging and the type of parts being manufactured. 
     In the prior art, the center section of the forging is normally pierced out and scrapped. With the present method and system, a smaller forging is formed in the center of a larger forging and the two forgings are thus produced at the same time. The two forgings as described above are then separated in the trimming and pierce operation. 
     With the present preferred embodiment, the process allows two parts to be forged together from one piece of steel and then are separated in the trimming and pierce operation. 
     While a preferred embodiment has been illustrated and described in detail in the drawings and foregoing description, the same is to be considered as illustrative and not restrictive in character, it being understood that only the preferred embodiment has been shown and described and that all changes and modifications that come within the spirit of the invention both now or in the future are desired to be protected.