Disc Cutter Research Articles

Prediction of TBM Disc Cutter Wear and Penetration Rate in Tunneling Through Hard and Abrasive Rock Using Multi-layer Shallow Neural Network and Response Surface Methods

Prediction of TBM Disc Cutter Wear and Penetration Rate in Tunneling Through Hard and Abrasive Rock Using Multi-layer Shallow Neural Network and Response Surface Methods

Prediction and analysis of slurry shield TBM disc cutter wear and its application in cutter change time

Disc cutter is mainly used in cutting through hard rock. Disc cutter wear is inevitable during tunnel boring machine (TBM) tunneling, and excessive wear can lead to a decrease in tunneling efficiency and increase construction risks. Therefore, the importance of predicting the disc cutter wear accurately and arranging the cutter change plan can never be overemphasized. In this study, disc cutter wear data and replacement records for three shield chamber openings were analyzed, which were collected from a water conveyance tunnel project in Guangdong, China. It was found that the normal wear failure accounted for approximately 76.19%, while the abnormal wear failure accounted for 23.81%, and the range of tools to be replaced due to normal wear continues expanded as the tunneling distance increased. Based on the observed wear data, it is found that the wear rate of edge tools is much lower than that of center tools, which does not conform to the normal wear rules. Subsequently, a new disc cutter wear prediction model was developed considering energy conversion and uneven thrust distribution for explaining this problem. The determination method of the energy conversion coefficient k and thrust distribution coefficient b was proposed, and they had been obtained from the wear data in the first replacement. On the other hand, the proposed model has higher accuracy in both cutter wear and cutter change range prediction compared with the existing models. However, the prediction accuracy of the proposed model will decrease with the increase of the tunneling distance, so the undetermined coefficients k and b need to be updated in a timely manner.

Correction to: Numerical simulation and experimental studies of rock‑breaking methods for pre‑grooving‑assisted disc cutter

Correction to: Numerical simulation and experimental studies of rock‑breaking methods for pre‑grooving‑assisted disc cutter

Prediction Model of Tunnel Boring Machine Disc Cutter Replacement Using Kernel Support Vector Machine

During tunneling processes, disc cutters of a tunnel boring machine (TBM) usually need to be frequently and unexpectedly replaced. Regular inspections are needed to check disc cutters’ status, which significantly reduces the work efficiency and increases the cost. This paper proposes a new prediction model based on TBM operational parameters and geological conditions that determines whether disc cutter replacement is needed. Firstly, an evaluation criterion for whether the cutters need to be replaced is constructed. Secondly, specific parameters related to the evaluation criterion are analyzed and 18 features are established on tunneling monitoring information. Then, the mapping model between the cutter replacement judgement and the established features is built based on a kernel support vector machine (KSVM). Finally, the data obtained from a Jilin water transport tunnel project is utilized to verify the performance of the proposed model. Test results show that the new model can obtain an average accuracy of 90.0% and an average F1 score of 86.2% on field data prediction based on data from past tunneling days. Therefore, the proposed data-predictive model can be used in tunneling to accurately predict whether disc cutters need to be replaced before human judgment, and thereby greatly improve tunneling safety and efficiency.

Research on the mechanism and performance of free-surface rock breakage by a disc cutter

To reveal the mechanism of free-surface rock cutting by a disc cutter and study the effect of cutting parameters on rock cutting performance, a numerical model of rock breakage by a disc cutter is established with the particle flow code (PFC). The numerical model of rock breakage by a disc cutter has been verified by rock breaking tests and can satisfactorily reproduce the rock cutting process. Hence, a numerical model was used to further study the rock breaking mechanism and effects of cutting parameters. The obtained results show that the penetration force first linearly increases and then instantaneously declines. The crushing zone gradually formed with increasing penetration force, and after that, the main crack within the rock rapidly extended to the free surface, which resulted in a decline in the penetration force. The formation of the crushing zone and main crack propagation were influenced by compression stress and tension stress, respectively, and the dissipation of energy was mainly in the stage of crushing zone formation. The peak penetration force has a linear relationship with breaking depth. The specific energy first increases and then decreases with increasing breaking depth, and the minimum value is in the range of 20–25 mm. With increasing tip width, the peak penetration force linearly increases, and the specific energy first increases and then decreases. The optimal rock breaking performance was obtained when the tip width was approximately 1 mm. Compared with the traditional rock breaking method, the preslotting method can significantly reduce the cutter load. When the breaking depth is 20 mm, the peak penetration force under the condition with a preslotting depth of 5 mm decreases by over 87% compared to that without preslotting. The preslotting method provides a potential approach for efficiently breaking hard and extremely hard rock.

Numerical simulation and experimental studies of rock-breaking methods for pre-grooving-assisted disc cutter

Numerical simulation and experimental studies of rock-breaking methods for pre-grooving-assisted disc cutter

Breakage Monitoring of Executive Body Cutters in Continuous Miner According to Mechanical Vibration Parameters. Part 1. Research Methodology

Vibromonitoring is the most methodologically developed and technically equipped with recording tools and data processing approach. However, in the sources of scientific and technical information about mining it is presented much less than other monitoring methods. One of the promising ways to solve this problem, in particular monitoring the breakage of cutting disc cutters of an executive body, is to use parameters of natural oscillations of the parts of gearboxes that occur during impulse loading due to such breakages. It should be noted that in the technically complex equipment of the mining industry, in particular in mining machines, there are many sources of vibration, the vibtaions of which are superimposed on each other. And it is not always possible to isolate and identify the required informative signal with the source. With this in mind the paper presents a research methodology on the possibility of monitoring the breakage of the executive body cutters on the example of the continuous miner “Universal 600” according to the parameters of natural vibrations of the executive body cutting discs arising from the breakage of the cutters. The place of registration of these vibrations is determined – the gearbox handles, on the output shafts of which cutting discs are placed. The frequency of such vibrations is set equal to ~5 Hz. The possibility of using the AGAT-M vibration analyzer with M/AC102-1A vibration sensors as a means of further research has been substantiated in the paper. The paper considers an option of placing vibration sensors on non-rotating gear housings of the executive body drive. An algorithm for recording vibration parameters has been developed, which makes it possible to separate its sources.

Impact-sliding behavior of Ni-based coating prepared on tunnel boring machine disc cutter material produced using a plasma transferred arc welding process

The working condition of the disc cutter of the tunnel boring machine (TBM) is extremely harsh and is severely worn during the rock-cutting and tunneling process. Reducing the wear rate of the cutter and extending the service life of the cutter are essential to improving the economic costs and safety of the TBM. This article explores the feasibility and effectiveness of using surface coatings to improve the wear resistance of the cutter ring. NiCrBSi/WC coatings with different current intensities were prepared on the disc surface using plasma surfacing technology. The wear performance of the coating was evaluated using a bespoke impact-sliding device that fits the actual working conditions, and the wear mechanism was studied in detail. According to the “tadpole-like” wear scar characteristics of the coating after the impact-sliding wear experiment, the wear scar zone can be divided into two regions: the impact region and the sliding region, which are consistent with the actual wear characteristics of the cutter ring. In addition, the wear behavior of the coating noticeably changed under each experiment parameter, and the evolution process of the impact-sliding wear of the gage cutter at each position can be well reproduced. When the impact angle was 45°, the wear depth and wear volume of the coating were significantly smaller than those of the uncoated samples. This is mainly due to the metallurgical bond between the Ni-based alloy zone (binder phase) and the spherical WC particles (hard phase) on the surface of each specimen. When impacted by the tribo-ball, the WC particles can undergo plastic deformation and relaxation through the Ni-based alloy zone under the applied force, thereby obtaining excellent impact and sliding resistance. When the impact angle was 60°, the impact dominates, causing the impact force to increase. Furthermore, compared with the uncoated specimens, the wear depth and wear volume of the coated specimens significantly increased, indicating that the anti-impact ability was seriously degraded in such situation. In summary, the powder composition and preparation process parameters should be reasonably selected according to the impact angle, and the impact-sliding wear experiment can effectively evaluate the impact and sliding wear performance of different coatings. This approach has an important directive function in the promotion and application of cutter ring coatings.

A cutting mechanics model of constant cross-section type disc cutter and its application based on dense core theory

The rock-cutting mechanism and force prediction model of disc cutter considering the effect of dense core are proposed in this study. According to the working characteristics of disc cutter and rock breakage theory, the contribution of dense core in the complex process of rock-cutting by disc cutter is investigated in detail. Based on the Mohr-Coulomb failure criterion of the rock, a theoretical analytical expression of dense core length is derived, and a cutting mechanics model of constant cross-section (CCS) type disc cutter is established; thus, the quantitative relationship between normal force and rolling force of a disc cutter and rock mechanical characteristics, cutter geometric parameters and cutting parameters is obtained. This model incorporates the size of a dense core. A rich full-scale linear cutting machine (LCM) database is developed from the literature and the theoretical force is compared with the experimental force. The results show that the proposed theoretical model can accurately predict 93% of the average disc cutter force acting on the rock uniaxial compressive strength (UCS) ranging from 8.4 to 355.6 MPa. As the rock UCS increases, the model prediction ability is significantly improved. In addition, the results comparison and performance evaluation between the proposed model and existing classical models prove that the proposed model is reasonable and reliable. Finally, the effects of model parameters (penetration, rock compressive strength, cohesion, internal friction angle and blade angle) on forces and efficiency of rock-cutting by disc cutter are also discussed. The results illustrate that the rock breakage regularity of disc cutter obtained based on theoretical model is consistent with that of actual engineering. The developed force prediction model for CCS-type disc cutter is a very practical tool for engineers in TBM excavation project.

Statement of Retraction: Modelling and Simulation of Surfacing Welding Remanufacturing for Tunnel Boring Machine Disc Cutter

Statement of Retraction: Modelling and Simulation of Surfacing Welding Remanufacturing for Tunnel Boring Machine Disc Cutter

Stability analysis and experimental research on ultrasonic cutting of wave-absorbing honeycomb material with disc cutter

To address the problem of the poor stability of ultrasonic machining of wave-absorbing honeycomb material, this study takes ultrasonic cutting of wave-absorbing honeycomb material with a disc cutter as the research object and establishes a multi-degree-of-freedom mathematical model of the cutting system based on the relative positions of the tool, the wave-absorbing honeycomb material, and the motion characteristics of the tool. On this basis, modal analysis of the disc cutter and the honeycomb cell wall plate is carried out to draw the Lobe diagram of ultrasonic cutting stability, the process experimental parameters are determined to accord to the solved stability Lobe diagram, and machining stability verification experiments are carried out. The experimental results show that the machining parameters in the stable zone of the Lobe diagram result in a neat and clean surface, less fibre pullout, a complete outer substrate, and less tool wear than those in the critical and unstable zones, thus verifying the correctness of the theoretical model and the stability Lobe diagram.

Improvement of a Technology of Use of a Road Milling Machine for Opening Cracks in Asphalt Concrete Pavements

The article presents improved technology of opening temperature origin cracks in asphalt and concrete pavements. The technology is based on the newly developed original design of a road milling machine with an automatically ranging width of an additional set of disc cutters and a diameter of a center plate. It is proposed to use it as part of an automatic system for milling (grooving) cracks of temperature origin in asphalt concrete pavements of highways. Dominant factors influencing the efficiency of road repairs in the process of milling the road pavement having cracks caused by temperature exposure with their broad unpredictable distribution relative to the axis of the main crack have been identified. The article also includes calculations of the total elongation of a curved part of an external surface of a disc-shaped element required for the identification of controllably changing axial overall dimensions of an assembled road milling machine. The calculations, as well as the efficiency and working ability of the proposed road milling machine, have been proved by experimental studies.

Application of Soft Computing Techniques to Estimate Cutter Life Index Using Mechanical Properties of Rocks

The wear of cutting tools is critical for any engineering applications dealing with mechanical rock excavations, as it directly affects the cost and time of project completion as well as the utilization rate of excavators in various rock masses. The cutting tool wear could be expressed in terms of the life of the tool used to excavate rocks in hours or cutter per unit volume of excavated materials. The aim of this study is to estimate disc cutter wear as a function of common mechanical rock properties including uniaxial compressive strength, Brazilian tensile strength, brittleness, and density. To achieve this goal, a database of cutter life was established by analyzing data from 80 tunneling projects. The data were then utilized for evaluating the relationship between rock properties and cutter consumption by means of cutter life index. The analysis was based on artificial intelligence techniques, namely artificial neural networks (ANN) and fuzzy logic (FL). Furthermore, linear and non-linear regression methods were also used to investigate the relationship between these parameters using a statistical software package. Several alternative models are introduced with different input variables for each model, to identify the best model with the highest accuracy. To develop these models, 70% of the dataset was used for training and the rest, for testing. The estimated cutter life by various models was compared with each other to identify the most reliable model. It appears that the ANN and FL techniques are superior to standard linear and non-linear multiple regression analysis, based on the higher correlation coefficient (R2) and lower Mean square error (MSE).

Experimental investigation on wear behaviors of TBM disc cutter ring with different cooling methods

The cutter ring of the TBM disc cutter is the main tool that directly contacts and cuts the rock. The cutter ring is prone to wear during the tunneling process, and the lower wear life will drastically reduce the tunneling efficiency and increase the construction cost. The working temperature of the cutter ring is an important factor affecting its wear resistance. TBM cutter cooling measures do not produce satisfactory results when tunneling in hard rock environments. When the cooling is not timely, the working temperature of the disc cutter ring will reach more than 400℃. Therefore, this paper carried out the cutter ring and rock wear experiment with water and air as the cooling medium. After analyzing the influence of different cooling methods on the weight loss, the working temperature and the wear mechanism, the result is obtained as follows: (1) The working temperature under water mist cooling is the lowest, and its wear loss is reduced by 65.2% compared with the non-cooling state. Under 30 m/s air flow rate cooling condition, the weight loss dropped by 22.5%. (2) The hardness of the cutter ring material will gradually decrease as the temperature rises. As the working temperature increases, the ploughing wear mechanism with plastic characteristics will appear. (3) The lubrication of water and the drop in the vertical force load after the rock absorbs water are also important factors to reduce the wear of the cutter ring.

A simulation method for free-form milling of cylindrical gears with disc cutters

Free-form milling is a flexible gear machining method that allows the use of general disc cutters to machine various gear types on a 5-axis machine tool. This paper proposes a two-dimensional simulation method for free-form milling of cylindrical gears with disc cutters. A mathematical model for free-form milling of cylindrical gears with disc cutters is constructed. By analyzing the spatial positional relationships between the cutter and the workpiece, the instantaneous contact line is derived and projected onto the gear end face; then, the intersection of the projected curves is used to obtain the final profile. This calculation method enables rapid simulation of the actual cutting conditions on the gear end face, which helps determine the machining interference and analyze the tooth profile accuracy during the gear machining process. The method proposed in this paper can also be used to analyze the sensitivity of geometric position errors of the machine tool axes.

Full-scale linear cutting tests to study the influence of pre-groove depth on rock-cutting performance by TBM disc cutter

To improve the tunnelling performance of tunnel boring machines in hard rock and extremely hard rock environments, abrasive water jet assisted rock breaking is a possible solution that has currently attracted considerable attention. In this approach, the depth of the pre-cut groove is a key factor affecting the performance of assisted rock breaking. To study the influence of the pre-groove depth on assisted rock breaking performance, a full-scale linear cutting test of pre-grooved rock was conducted with a disc cutter. The influence of the pre-groove depth on the rock breaking effect under the same-trajectory mode (SM) and different-trajectory mode (DM) of assisted cutting was explored, and the mechanism of assisted rock breaking with different groove depths was revealed. Compared with the complete cutting mode (CM), the results showed that the normal force (FN), rolling force (FR), side force (Fs), and specific energy (SE) under SM decrease as the groove depth increase. Under DM, the FN, FR, and SE decrease as the average groove depth on both sides increase, and the Fs decreases as the minimum groove depth increases. In SM and DM, the cutting SE first decreased rapidly and then tended to decrease slowly as the groove depth increased, indicating the existence of an optimal groove depth. The rock fracture patterns under SM and DM are more prone to tensile failure, which significantly reduces the rock cutting force and SE of the disc cutter. These results can provide inspiration for the design and construction of new types of tunnel boring machines that are assisted by abrasive water jet pre-grooving.

Dynamic Rock-Breaking Process of TBM Disc Cutters and Response Mechanism of Rock Mass Based on Discrete Element

Rock-breaking efficiency of full-face rock tunnel boring machine (TBM) is closely related to the performance of the disc cutter and the characteristics of the rock mass. In the point of view of mesomechanics, the particle flow code (PFC) is used to establish a numerical model of the rock mass and the disc cutter, and the process of TBM disc cutter intrusion into the rock mass is analyzed. The dynamic response mechanism and crack evolution process of the rock mass under the action of the disc cutter are studied on the basis of micromechanics, and the relationship between the rock mass crack, penetration, and cutting force during the intrusion of the disc cutter is revealed. The sensitivity analysis is carried out on the confining pressure conditions and the influence parameters of the disc cutter spacing. The results show that the rock breaking by disc cutter undergoes the transformation characteristics of compaction, shearing, and tension failure modes, and the failure process of the rock mass is the joint action of tension and shear. In the whole process of rock breaking, the disc cutter has the phenomenon of repeated loading-unloading alternation and leaping rock breaking; after the penetration of the disc cutter reached 9.0 mm, penetration creaks begin to appear on the surface of the rock mass; the penetration was obviously reduced with the increase of confining pressure, and it is mainly the penetration cracks on the surface; after the disc cutter spacing reaches 100.0 mm, there is no penetration crack between the two disc cutters. The research conclusion can provide a reference for the disc cutter optimization design.

Pose Determination of the Disc Cutter Holder of Shield Machine Based on Monocular Vision.

The visual measurement system plays a vital role in the disc cutter changing robot of the shield machine, and its accuracy directly determines the success rate of the disc cutter grasping. However, the actual industrial environment with strong noise brings a great challenge to the pose measurement methods. The existing methods are difficult to meet the required accuracy of pose measurement based on machine vision under the disc cutter changing conditions. To solve this problem, we propose a monocular visual pose measurement method consisting of the high precision optimal solution to the PnP problem (OPnP) method and the highly robust distance matching (DM) method. First, the OPnP method is used to calculate the rough pose of the shield machine’s cutter holder, and then the DM method is used to measure its pose accurately. Simulation results show that the proposed monocular measurement method has better accuracy and robustness than the several mainstream PnP methods. The experimental results also show that the maximum error of the proposed method is 0.28° in the direction of rotation and 0.32 mm in the direction of translation, which can meet the measurement accuracy requirement of the vision system of the disc cutter changing robot in practical engineering application.

Experimental and numerical study on the indentation behavior of TBM disc cutter on hard-rock precutting kerfs by high-pressure abrasive water jet

Experimental and numerical study on the indentation behavior of TBM disc cutter on hard-rock precutting kerfs by high-pressure abrasive water jet

Rock‐Breaking Laws of Disc Cutters with Different Height Differences in Hard Rock Strata

When shield machine traverses through hard rock mass, disc cutters will be abraded to different degrees. Excessive height difference exists between adjacent disc cutters, which critically affects the rock‐breaking efficiency. Relying on a shield section of hard rock mass in Qingdao, the disc cutter abrasions are measured on site, and the reason for low construction efficiency is analysed. Subsequently, the discrete element method is used to study the rock‐breaking law under different height differences of disc cutters. The ultimate cutter height difference for rock breaking is obtained. According to this, the cutter adjustment scheme is proposed to reduce the cutter height differences on site. Comparing shield tunnelling parameters before and after the cutter adjustment, it is found that the construction efficiency is significantly improved. The results are of great significance for improving the rock‐breaking efficiency and increasing advancing speed of shield in hard rock mass.