Hot Upset Forging Mold Shape Precision
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Solution Overview
Problem
Existing hot upset forging methods face challenges in achieving high shape precision, particularly for workpieces with a height-to-diameter ratio exceeding 3, where buckling and abnormal deformation are concerns.
Innovation Solution
A hot upset forging method involving a mold with specific relationships between the insertion hole and workpiece dimensions, including a similar shape configuration, height constraints, and diameter ratios to prevent buckling, along with multiple forging cycles using the same mold to achieve a final product with a height-to-diameter ratio of 3 or less, and optional chamfered portions to enhance stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a mold with height lower than workpiece is employed for hot upset forging of workpiece with h/d>3, then buckling is prevented, but shape precision deteriorates
Solution Approach 1:
The workpiece is preliminarily heated to austenite region temperature before insertion into the mold. This preliminary thermal preparation ensures the workpiece has appropriate plasticity and temperature uniformity before deformation, preventing abnormal deformation and buckling while enabling precise shape control during subsequent forging operations
Solution Approach 2:
The invention changes the temperature parameter by heating the workpiece to austenite region (727°C or higher) before forging. This parameter change transforms the material properties, enabling controlled plastic deformation and preventing buckling while achieving high shape precision in the final forged product
2Ease of manufacture
If free deformation portion is allowed to bulge out in radial direction, then plastic deformation is achieved, but abnormal deformation occurs
Solution Approach 1:
The mold is designed with differentiated local structures: a tapered portion at the insertion hole for controlled deformation initiation, and a parallel portion with precise dimensions for final shape control. This local quality differentiation enables the workpiece to undergo necessary plastic deformation while preventing abnormal bulging and ensuring high shape precision
Solution Approach 2:
The workpiece is preliminarily heated to austenite region temperature before insertion into the mold. This preliminary thermal preparation ensures the workpiece has appropriate plasticity and temperature uniformity before deformation, preventing abnormal deformation and buckling while enabling precise shape control during subsequent forging operations
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This method effectively prevents abnormal deformation along the entire workpiece length, ensuring high shape precision and reproducibility by controlling deformation within the mold and reducing buckling risks through precise mold and workpiece alignment.
Implementation Method 1
a large amount of plastic deformation has to be imparted to produce such forged products, necessitating upsetting of elongated material
Data Source
AI summary
Provided is a hot upset forging method enabling high shape precision to be obtained. The hot upset forging method includes inserting a workpiece (1), with a bottom face diameter d and a height h satisfying h/d>3, into an insertion hole provided passing through a mold (2) of a height H disposed on an anvil (4), and increasing the diameter of the workpiece (1) while decreasing the height of the workpiece (1) to form a forged material. The mold satisfies the following relationships (1) to (3). (1) A shape of the insertion hole and the cross-sectional shape of the workpiece are substantially similar shapes. (2) The height h of the workpiece (1)≦the height H of the mold (2). (3) A largest diameter dl of the workpiece 1, and the maximum inner diameter D of the insertion hole, in the height range of the workpiece (1), satisfy dl<D≦dl×1.5.