Innovative Forging Processes for Superior Hydraulic Cylinder Bottoms

In hydraulic cylinder system, cylinder bottom is an important structural component, its quality and performance are directly related to the stability and operation efficiency of the whole system. In the production of cylinder bottom, the traditional casting process often faces the problems of insufficient mechanical properties and poor fatigue resistance, which greatly limits its application in high-load working environment.

In order to solve this technical bottleneck, the feasibility of replacing the traditional casting process with die forging process is deeply studied in this paper, and the comprehensive performance of the cylinder bottom is significantly improved by optimizing the process parameters and mold design. This paper will introduce the process of this transformation and its effect in detail, hoping to provide valuable reference for related manufacturing enterprises.

The Role of Cylinder Bottom in Hydraulic Cylinder System

Cylinder bottom is an important part of automotive hydraulic cylinder system, its performance and quality directly affect the stability and mechanical performance of the whole cylinder system. As a connecting part between the cylinder and the tie rod, the role of the cylinder bottom is to carry the huge tensile stress and compressive stress, and transfer the oil pressure to the piston rod to promote its reciprocating movement. The reliability and robustness of the hydraulic system depends largely on the manufacturing quality and operating state of the cylinder bottom. However, the traditional cylinder bottom manufacturing usually adopts the casting process, which is low-cost, but the product is prone to defects such as porosity, porosity, cracks and so on, which greatly affects the overall performance of the cylinder bottom, especially when it is easily damaged under large loads and tensile stresses, resulting in the instability of the cylinder system.

Introduction and Advantages of Die Forging Process

In order to overcome the shortcomings of these casting processes, many domestic manufacturers have gradually introduced new die forging processes to replace traditional casting methods. Forging process through the plastic deformation of the metal material, giving it a more uniform internal structure and excellent mechanical properties, which not only improves the fatigue resistance and impact resistance of the product, but also effectively improves the mechanical properties and durability of the cylinder bottom. In this paper, a new casting and forging process for cylinder bottom castings is studied and proposed. Aiming at the defects of fracture and fatigue resistance of cylinder bottom castings, a scheme of free forging and die forging is proposed to optimize the design.

Numerical Simulation

Firstly, we analyze the fracture problem of the cylinder bottom castings provided by a company in actual use, and conclude that its low fatigue resistance is the root cause of the instability of the cylinder system. Therefore, the research team designed a set of free forging billet - die forging process, and developed a matching mold structure. After the die design is completed, the best billet making scheme is selected by numerical simulation of different billet making schemes, and the key process parameters such as billet preheating temperature, die preheating temperature and forging forming speed are determined. On this basis, a series of product trial production was carried out to verify the reliability of mold design and process selection.

Although the die forging process has effectively improved the overall performance of the cylinder bottom, some problems such as pits, oxide skin and decarburization are still found in the actual production. Therefore, this paper further optimized the process parameters, adopted the orthogonal experimental design method, carried out numerical simulation analysis on the forming maximum load, mold cavity wear and forging damage and other key indicators, and finally determined the optimal process parameter values. Including billet preheating temperature of 1160℃, mold preheating temperature of 300℃, forging forming speed of 40mm/s and friction factor of 0.2. Through the optimization of these parameters, the problems of pits and oxide skin on the forging surface are effectively solved, and the surface quality and mechanical properties of the product are further improved.

Multi-objective Optimization of Die Structure

Based on the optimization of process parameters, the response surface method was used to optimize the mold structure and blank size. It is found that four main structural parameters, such as die inclination, bridge height, skin thickness and forging blank diameter, have significant effects on forming load, die wear and forging damage. Through finite element numerical simulation, the optimal structural parameters of die inclination of 4°, flash bridge height of 3mm, skin thickness of 18mm and die forging blank diameter of 220mm were finally determined, and applied in actual production, and good production results were obtained. This series of optimization not only avoids casting defects, but also significantly improves product quality and overall mechanical properties.

Sum up

Through the in-depth research on the casting and forging process of the cylinder bottom in this paper, it not only provides a solid guarantee for the reliability of the cylinder system, but also provides a valuable technical reference for the relevant manufacturing enterprises in practice. In addition, this research result also has reference significance for the manufacture of other similar large-scale symmetrical forgings, and is expected to promote the further development and application of precision forging technology. It is hoped that the content of this paper will be helpful to everyone and provide inspiration for future process improvement.