Patent Application
20060123877
1. Field of the Invention
The present invention relates to a heading die. More particularly, the present invention relates to a hot-forging heading die used in metalworking to form a “head” on the end of a steel rod, such as in the manufacture of ejector pins.
2. Description of the Related Art
Heading dies have long been used in cold and hot forging metalworking processes to form an enlarged “head” on the end of a metal rod that will define an element of the finished part. For example, a number of components used in the construction of injection molds, such as ejector pins, core pins, return pins, valve pins, and sleeves, as well as many non-molding industry parts such as screws, bolts, rivets, etc., are typically configured to have an elongated body with a head at one end to limit travel, orient the component or provide a finished or partially formed end for further machining processes.
The typical construction of a heading die comprises a hardened steel ring with a cylindrical carbide insert. Pre-forming the internal configuration during the manufacture of the carbide insert and/or normal machining methods are used to create an axial bore completely through the insert, the rod or body of the part passing through this bore during the forging process. The heading cavity is created by machining a suitably sized counterbore (concentric with the axial through bore) that will ultimately form the head during the cold or hot forging process. The prior art heading dies used for this purpose have a cavity on only one side of the die. Accordingly, when the insert became chipped, otherwise damaged or worn beyond acceptable tolerances, the die became unusable, necessitating its complete replacement by a new die.
The present invention overcomes the shortcomings of prior art constructions by providing a die configuration that includes two heading cavities formed in opposite ends of the carbide insert. The heading die of the invention comprises a hardened steel ring with a cylindrical carbide insert, as known in the art. The through bore and first cavity are likewise finished or created according to normal machining and metal-forming methods. The die is then inverted during the machining process and a second cavity formed in the opposite end of the insert. The second cavity can be identical to the first cavity or manufactured to provide the shape for an alternate head configuration.
This double-cavity construction of the present invention increases the utility and economy of the heading die. More specifically, the cost per cavity is reduced by nearly fifty percent compared to the prior art since a single carbide insert is used for both cavities. The only additional machining is for the second heading cavity since the through hole for the stem (rod) of the part has to be machined completely through the carbide insert even in a single cavity die.
Referring first to
The insert 14 undergoes a suitable machining process to create an axial bore 20 that extends entirely through the length if the insert 14. A first heading cavity 22 is then machined in the upper end surface 16 of the insert 14. As illustrated in the drawing, the first heading cavity 22 is concentric with the axial bore 20, so that both the first cavity 22 and axial bore 20 are concentric with the outer diameter 30 of the insert 14.
After the first heading cavity 22 is properly formed, the heading die 10 is inverted in the during the machining process, so that the lower end surface 18 of the insert 14 is accessible for the final machining operation. In particular, a second heading cavity 24 is machined in the lower end surface 18 of the insert 14. As with the first heading cavity 22, the second heading cavity 24 is concentric with the axial bore 20 and the outer diameter 30 of the insert 14. It is generally desirable for the second heading cavity 24 to have the same geometry as the first heading cavity 22 to facilitate maximum utility during the manufacturing process, as described in more detail below.
In its finished form, the heading die 10 is suitable for use in a cold or hot forging metalworking process wherein a metal rod or sleeve used to form a part having an elongated body portion 32 and an enlarged head portion 34, as shown in
The foregoing discussion and the illustrated embodiment of the invention have been in the context of the use of the heading die in conjunction with the manufacture of an ejector pin. However, it will be apparent to those skilled in the art that various changes and modification can be made without departing from the concepts of the present invention, allowing it to be used in the manufacture of numerous products. For example, while the heading die 10 is shown to have first and second cavities with identical shapes, it may be desirable under some circumstances to have a different geometry for the second cavity. It is therefore intended to encompass within the appended claims all such changes and modification that fall within the scope of the present invention.
