Considering that conventional experiment methods are time-consuming, laborious and expensive, on the premise of understanding the rock fragmentation mechanism of disc cutter cutting and laser drilling respectively, a novel simulation modeling method of rock breaking of tunnel boring machines (TBM) disc cutters assisted with the laser is proposed. The method includes two-step modeling features: 1) in the first step, a finite element model of laser drilling is established in ANSYS, and then the morphology of a single hole and fissures can be predicted using the birth and death element method; 2) in the second step, a rock finite element model with multiple holes is reconstructed in HyperMesh, where the holes with a given hole spacing n have the same shape as the first step; then, ANSYS/LS-DYNA is used to carry out the simulation analysis, thereby indirectly simulating rock breaking process of TBM cutters assisted with laser. Finally, to demonstrate the applicability of the method, a simulation case study is carried out and the obtained values such as cutting force, the amount of rock breaking, and specific energy consumption are according with theoretical expectations. It can be seen that this paper provides an economical and feasible solution for the study of laser-assisted rock breaking.

As H13 steel is a common material for cutters of Tunnel Boring Machine (TBM), the research on surfacing remanufacturing performance is of great value. In this paper, the phase composition of the surfacing layer of H13 steel after gas metal arc welding (GMAW) was analyzed by exploring the precipitation of hard phase in the molten pool, and the microstructure evolution of the surfacing layer was revealed. Then, we carried out simulation modeling analysis on H13 steel surfacing remanufacturing. Results show that: (1) the surfacing layer is combined with the base metal by physical metallurgy without obvious defects such as pores, inclusions and cracks in the surfacing layer; (2) the hardness of the surfacing layer is 60 HRC, which is about 1.5 times of that of the base metal; (3) the stress is mainly concentrated in the arc starting and ending points, followed by the external constraints on both sides of the surfacing layer; (4) the deformation of surfacing layer is slight, which does not affect the forming quality of base metal, while the deformation of base metal is relatively severe. This paper verifies the feasibility of H13 steel remanufacturing from experimental and simulation, providing theoretical basis for future engineering practice.

Linear guides are widely used in automation, aerospace production, and medical care. It is currently one of the most concerning issues how to monitor its surface quality in the manufacturing process automatically. Considering that it is difficult to achieve the automatic separation of complicated surface defects with mutual interference, a novel method is proposed to adaptively determine the center point of clustering and separates defects through using the density peaks and spectral multiple-manifold clustering(SMMC). First, for the extracted binary image of the surface defects, the principal component analyzer of mixed probabilities is used to estimate the local tangent space of each pixel. In addition, the similarity matrix between the local tangent space of each defect location is improved. Then, to overcome the problem that SMMC must manually determine the number of clusters, an improved method based on clustering by density peaks is presented to determine the clustering center point according to the similarity matrix. Finally, the pixels included in each principal component analyzer are assigned to different defect manifolds through SMMC. The surface defect locations ultimately achieve separation and detection. The experimental results show different defects with mutual interference on the surfaces can be automatically separated and more accurately detected.

Given that the heat treatment states of the base metal have a great influence on the surfacing repair layer, this paper carried out a feasibility study for the remanufacturing of the failed cutter rings of TBM disc cutters with uniform wear (hereinafter referred to as normally-worn ring) using the gas metal arc welding technology (GMAW). Firstly, this paper developed a heat treatment process route for H13 steel cutter rings. Secondly, the heat treatment process is numerically analyzed based on the developed route, and the rationality of the route is verified from the distribution characteristics of temperature, phase, and stress fields. Subsequently, heat treatment tests were carried out, and the physical and mechanical properties of the base metal samples prepared under laboratory conditions were evaluated respectively and systematically. Based on the comprehensive performance evaluation value calculated by the weighted comparative analysis method, it was clear that the comprehensive performance of the quenched base metal samples was 7.6% higher than that of the engineering cutter ring interior. Therefore, it is reasonable to replace the failed engineering cutter rings repaired under laboratory conditions with the prepared samples as economical alternatives. Finally, the remanufacturing of the base metal samples using GMAW was carried out, and then the remanufacturing performance of the base metal samples was analyzed. The study concluded that the comprehensive performance of the surfacing repair layer was slightly lower than that of the engineering cutter ring edge (4.1%), thus proving that the idea of surfacing remanufacturing of the normally-worn ring proposed in this paper was basically feasible.