Advancements in Precision Forging Technology
Precision forging is a manufacturing process that creates components with exceptional strength, intricate shapes, superior surface quality, and precise tolerances. A critical factor in achieving flash-free precision forging is the meticulous preparation of the forging blanks. In the production of steel components, the most prevalent method for preparing these blanks is through billet shearing.
During the die forging process, the forged blank undergoes transformations to attain a specific geometric configuration through one or multiple forging stages. For elongated components—those where the length exceeds the cross-sectional dimension—this process typically involves several steps, including the redistribution of the blank's mass, shaping the cross-section, and final forming. In traditional shape forging, excess material often results in burrs that must be removed prior to the final stages of forging.
Recent advancements in hot forging techniques for steel have significantly transformed shape processing technologies. Innovations in forging dies and equipment, along with enhancements to the forging process itself, have led to improvements in both economic efficiency and product quality. Among these advancements, the importance of burr-free forging is increasingly recognized.
Precision forging offers a cost-effective alternative to traditional methods for creating complex geometries. For instance, components like connecting rods, which would typically require extensive machining to achieve precision, can now be produced through precision forging, achieving tolerances in the range of IT8 to IT10. The elimination of burrs in this process not only removes the need for additional burring operations but also conserves the metal that would otherwise be wasted in the creation of those burrs. Achieving this requires a forging process that aligns closely with the characteristics of the final parts, including quality preforming techniques like cross wedge rolling, using thicker materials in closed dies, and ensuring accurate cross-sectional dimensions for final precision forging.
For effective burr-free die forging, it is essential to work with blanks that are small in size, accurately shaped, and maintain a consistent volume. Typically, forged blanks are produced from steel bars using cutting equipment designed for blanking. Compared to traditional sawing, this shearing technique offers higher speed and precision, leading to better material utilization by eliminating kerf waste.
To maintain cutting accuracy, it is vital to assess the quality and dimensions of the blanks post-blanking. Adjustments to production parameters, such as the cutting gap and speed, are necessary to ensure a flat cut surface that is perpendicular to the axis of the steel bar. The integration of an exciter at the cutting edge can enhance multiple process parameters simultaneously, improving the surface quality of the cut while minimizing the angle of inclination to below one degree, thus reducing surface waviness. This type of cutting device is particularly advantageous for producing forged blanks that require straightness and defect-free shear planes.
A research initiative conducted by a leading institute examined the impact of a trimming tool shaker on the quality of cut surfaces. The study focused on the influence of low-frequency vibrations on the trimming process, exploring various excitation methods including piezoelectric, hydraulic, and mechanical vibrations.
Initial tests demonstrated that employing hydraulic excitation during the cutting process significantly improved the quality of the cut surface, which in turn enhanced the quality of the forged cross-section.
Key adjustments to the cutting gap—defined as the horizontal distance between the cutting edges—are crucial for optimizing the quality of the cut. Factors influencing the cutting gap include the rigidity of the cutting machine, the diameter of the steel bar, and the material's tribological properties. An increase in the cutting gap often leads to a decline in the flatness of the cut surface, highlighting the need for careful calibration.
In collaboration with a renowned research institute, rigorous testing was conducted to identify the optimal cutting gap for achieving a flat cross-section. This research utilized digital analysis to develop a methodology for determining the appropriate cutting gap for hydraulically excited cutting machines. Future efforts aim to create dedicated modules for specific machines, while also developing universal equipment solutions for broader applications. The collaboration received support from leading manufacturers of cutting machines, allowing for the establishment of general principles regarding the expansion of cutting gaps. This knowledge may simplify future adjustments and enhance overall performance in precision forging applications.
