Metal deforming – With temperature modification of tool or of specified... – Distinct temperature modifications at distinct locations of...
Reexamination Certificate
1998-07-14
2001-01-30
Larson, Lowell A. (Department: 3725)
Metal deforming
With temperature modification of tool or of specified...
Distinct temperature modifications at distinct locations of...
C072S364000
Reexamination Certificate
active
06178800
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of Invention
This invention is directed to methods and apparatuses for heating workpieces that are to be forged into metal parts. More particularly, this invention is directed to methods and apparatuses for heating workpieces (also known as billets, blanks or cuts) in such a way that different portions or “zones” of the workpieces are at different temperatures.
2. Description of Related Art
Many metal parts have distinct but integral portions that are of different configurations. An example is a part having a reduced portion at one end and an upset portion at the other end. Certain of these parts, including parts having reduced and upset end portions, must be manufactured, using present manufacturing processes and equipment, in separate and distinct steps-one step to form each distinct portion.
For example, it is known to form parts having a reduced portion at one end and an upset portion at the other end by first cold extruding a workpiece to form the reduced portion, and subsequently warm forging the workpiece to form the upset end. The reduced and upset end portions have not been formed by a single process, because (1) the upset end portion cannot be formed by cold extrusion and (2) both portions cannot be formed by a single warm forging stroke. As to the latter point, if a manufacturer attempted to manufacture such a part by a single warm forging stroke, the upset end of the workpiece would form first. Excessive tonnage (or compressive force) would then be exerted on the workpiece because the punch would be trying to force the already-upset workpiece into a reduced portion of the die cavity. This excessive force would result in underfilling of the reduced end portion (
FIG. 6
) of the part, while the upset end portion would have excess material or flash (FIG.
7
).
It would obviously greatly increase productivity and reduce the cost of producing parts having distinct but integral portions of different configurations if the processing steps and/or equipment required to form the parts are reduced and/or simplified, e.g., if such parts can be produced in a single forging apparatus by a single forging stroke.
In this regard, parts having a flanged middle and concave recesses at the ends thereof have been produced in a single warm forging stroke by using a workpiece which has been heated such that its end portions have a temperature greater than the temperature of its center portion. However, certain parts having integral portions of other distinct and separate configurations cannot be formed by a single warm forging stroke using a workpiece which has been heated such that its end portions have a higher temperature than its middle portion, including parts having upset end portions and reduced end portions, as discussed above.
Accordingly, there is a need in the art for methods and apparatuses that enable manufacturers to form parts having integral portions of different configurations in a single process step using a single press.
SUMMARY OF THE INVENTION
This invention provides methods and apparatuses for heating workpieces that are to be formed into parts having integral portions of different configurations, such as upset ends and reduced ends. The workpieces are heated such that the portions of the workpieces which correspond to the portions of the parts having different configurations differ in temperature. Because the respective workpiece portions have different temperatures, these workpiece portions will deform in sequence during the warm forging process, i.e., the portion at the higher temperature will deform first. Thus, to form parts having upset portions and reduced portions, the portion of the workpiece corresponding to the reduced portion of the finished part can be heated to a higher temperature, and that portion of the workpiece will deform first (forming the reduced portion first). This substantially eliminates the problem of underfill on the reduced portion and flash on the upset portion as discussed above.
Certain embodiments of this invention include a plurality of heating assemblies. The workpieces are advanced through the heating assemblies in a series of discrete steps, or increments, i.e., each workpiece is in a first position for a set period of time, then moved to a second position for the set period of time, etc. The heating assemblies are spaced and located such that one portion of the workpiece is in one heating assembly and the other portion of the workpiece is either in another heating assembly or is not in any heating assembly during each step or increment. Further, one portion of each workpiece is exposed to N heating steps, while the other portion is exposed to M heating steps, where M<N, such that the first portion is at a higher temperature than the second portion.
In certain embodiments of this invention, a workpiece holding assembly is provided to periodically engage and retain the workpieces in a desired position relative to the heating assemblies. This workpiece holding assembly may include a clamping finger assembly including at least one clamping finger, and may be activated by a pneumatic cylinder.
Some embodiments of this invention include a pusher assembly which advances the workpieces through the heating assemblies. The pusher assembly may be activated by, for example, a pneumatic cylinder. Preferably, the operation of the workpiece holding assembly is synchronized with the activation of the pusher assembly such that the clamping finger assembly of the workpiece holding assembly is raised when a workpiece is being moved by the pusher assembly and is lowered into a clamping position when the workpiece stops.
REFERENCES:
patent: 2507817 (1950-05-01), Ropp et al.
patent: 2669647 (1954-02-01), Segsworth
patent: 2953794 (1960-09-01), Klooz
patent: 3007181 (1961-11-01), Felber
patent: 3885411 (1975-05-01), Szeliga
patent: 4222260 (1980-09-01), McDermott
patent: 58-25837 (1983-02-01), None
Edmonds Kevin
Stenger Jeffery
Larson Lowell A.
MSP Industries Corporation
Oliff & Berridg,e PLC
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