Asynchronous coupling force of dual forging manipulator frequently results in poor forging and even equipment failure. In this paper, a synchronous control strategy in dual forging manipulator systems (DFMS) is proposed to stabilize its operation. Kinematic model of the hanging system and finite element model of the forgings are established to investigate the relationships of tension, forging deformation and deformation rate. The rigid-flexible coupling model of DFMS is further established and simulated concerning hydraulics, mechanics and controls. A correction based on the independent feedback state difference is concerned, simulated results show good agreements with experimental data, validating the dead zone compensation algorithm of the proportional valve. Moreover, by the control strategy, the vertical synchronous error of the pincers end is rather small as ± 0.125 mm. The methodology presented in this paper represents a fundamental step towards the cooperation of DFMS and the press to realize collaborative operations.

Purpose: This study aims to investigate the causes of leakage in radial oil seals under dynamic eccentricity, elucidate the influence of operating parameters on leakage failure and develop methods for predicting and preventing such leakage. Design/methodology/approach: Based on the principle of cam motion and considering viscoelasticity, develops a motion model of the compression and release of the shaft seal and proposes a method to determine its failure. In addition, this study quantifies the leakage gap and formulates a quantitative calculation model to accurately determine the location and shape parameters of the leakage gap. Findings: Leakage gaps predominantly occur during the release phase of the shaft seal. Their presence can be identified by comparing the descending times of the seal and the shaft during this phase. An increase in rotation speed and eccentricity heightens the likelihood of gap formation, with both the dimensions and leakage rate of the gap increasing as these factors escalate. Eccentricity, in particular, has a more pronounced effect on gap formation. Originality/value: This study clarifies the failure mechanisms of radial oil seals under dynamic eccentricity and introduces a criterion for identifying leakage gaps, providing valuable theoretical guidance for the design and optimization of radial oil seals. Peer review: The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-05-2024-0192/.

With the increasing demand for lightweight construction machinery, it is of great significance to study non-metallic materials that can replace steel plates to make hydraulic oil tanks (HOTs). To explore the feasibility of making HOTs with three materials—cross-linked polyethylene (XLPE), polypropylene (PP), and nylon (PA)—this paper takes 28 L and 115 L volumes commonly used in construction machinery, such as forklifts and loaders, as the design volume and obtains non-metal HOT products of good forming quality by regulating the process parameters. Based on the test methods and evaluation bases of the fuel tank in the national standard, the normal-temperature pressure test, high-temperature pressure test, and low-temperature impact test are designed according to the working conditions of the HOTs. Finally, the non-metallic HOT products are tested. The results show that the rotational molding of XLPE material is the easiest, and products of all sizes can be molded, but the mechanical properties and thermal stability of the products are poor. The low-temperature impact resistance of PP products is poor. PA material can be used to create small HOTs, and the product performance is excellent. This research serves as a valuable reference for the non-metallic and lightweight design of HOTs.

This paper aims to study the natural heat dissipation capacity of a hydraulic tank during its miniaturization revolution. A theoretical model of heat dissipation was built up on the basis of experimental analysis. Then, the natural heat dissipation power was deduced and shown to be relevant. Influencing factors were analyzed, which were the oil height proportion, design proportion, volume, material type, and wall thickness. The results showed that the heat dissipation power is proportional to the height of the oil in the tank. The power increases with the height proportional coefficient k2, while it first decreases and then increases with the length proportional coefficient k1. The lengthwise coefficient obviously has a more significant effect. The influence degree of reduction methods on natural heat dissipation is in the following order: length reduction > equal proportion reduction > height reduction > width reduction. Additionally, when the thermal conductivity λ is greater than 10 W/(m·K), the material and wall thickness of the tank slightly influence the heat dissipation capacity; otherwise, the influence is evident.