With the in-depth integration of intelligent manufacturing and energy-efficient manufacturing, energy consumption should be taken as an important indicator to meet the development philosophy of ...low-carbon manufacturing while continuously pursuing manufacturing efficiency. The intelligent estimation of energy consumption for machined parts is the basis for establishing an energy-efficient intelligent manufacturing system. STEP-NC is one of the practical schemas to implement an intelligent manufacturing mode in the CNC machining field. Hence, this paper proposed an estimation methodology of energy consumption based on the STEP-NC program to realize the estimation of the staged and overall energy consumption for parts. Firstly, the influencing factors of energy consumption are analyzed in detail and the data model of energy consumption is extended to the STEP-NC standard accordingly. Secondly, the energy consumption estimation methodology based on the machining feature was constructed, and the mapping relationship between STEP-NC program and the estimation method was established. Finally, the energy consumption estimation framework with the STEP-NC program as input is developed while the validity of the methodology is verified by practical machining experiments. By comprehensive analysis, the methodology shows promising results in efficiency and application prospect, which lays a foundation for further intelligent energy-efficient research.
This study proposes a method for extracting the machining region machined by swarf machining and hole drilling from a Standard Triangulated Language (STL) data exported from 3D CAD and automatically ...generating a tool path. First, a method is proposed for extracting the machining region and obtaining geometric features, such as slope, curved surfaces, holes, and pockets, from the STL data exported from 3D CAD. The STL data uses only triangular mesh data and drops all information, which is necessary for extracting the removal volume for the machining and geometrical characteristics. Then, a half-edge algorithm is proposed that clarifies the connection relationship between planes by integrating triangular meshes of the same plane in a model in STL data and realizes automatic extraction of machining regions through the analysis of shape data. Subsequently, a method is proposed to determine the 5-axis indexing posture and generate a tool path according to the geometrical features of the machining region. A machining experiment was conducted to validate the effectiveness of the proposed method. As a result of the machining experiment, it was confirmed that the tool path automatically generated from the STL data exported from 3D CAD can be machined without any problems and with a practical level of accuracy.
•A multi-granularity NC program optimization approach for energy efficient machining which includes the granularity of a group of NC programs for a setup and the granularity of a NC program.•On the ...first level of granularity, the execution sequence of the NC programs for the setup of a part is optimized to reduce the energy consumed by the cutting tool change among the NC programs.•On the second level of granularity, the execution sequence of the features in the same NC program is optimized to reduce the energy consumed by the cutting tool's traveling among the machining features.•Experiments on the practical cases show that the optimization results are promising and the approach has significant potential of applicability in practice.
NC programs are widely developed and applied to various machining processes. However, the lack of effective NC program optimization strategy for the machining energy efficiency has been crippling the implementation of sustainability in companies. To address this issue, a multi-granularity NC program optimization approach for energy efficient machining has been developed and presented in this paper. This approach consists of two levels of granularities: the granularity of a group of NC programs for a setup where the features are machined on a single CNC machine with the same fixture and the granularity of a NC program. On the former level of granularity, the execution sequence of the NC programs for the setup of a part is optimized to reduce the energy consumed by the cutting tool change among the NC programs. On the latter level of granularity, the execution sequence of the features in the same NC program is optimized to reduce the energy consumed by the cutting tool's traveling among the machining features. Experiments on the practical cases show that the optimization results from this approach are promising and the approach has significant potential of applicability in practice.
At present some CAD/CAM systems allow to create strategies or macros to accelerate the process of creation NC programs. The article deals with the development of experimental strategies in the ...CAD/CAM system. These strategies allow to remove repetitive tasks and allow to accelerate the process of creation the NC programs for machine tools. Feature analysis contained basic types of features and additional attributes of features. This feature analysis is based on possibilities of CAD/CAM system.
In wire electrical discharge machining (WEDM) that can perform 2-D or 2.5-D machining, 3-D complex shape machining is also possible via the addition of a rotary axis on the NC table. Several examples ...of pin-shaped machining using a rotating shaft like spindle have been previously reported. Alternatively, machining using a rotary axis as an indexing device has also been reported. In these machining processes, the rotary axis is not servo controlled. Conversely, a spiral groove is formed on the outer circumference of the round bar by gripping the round bar workpiece on the rotary axis and performing machining in synchronization with the
x
- and rotary axes. In this machining, the gap control in electrical discharge machining is performed along the
x
- and rotary axes. Furthermore, complicated shape machining becomes possible by adding a 2-axis rotary axis of rotation and tilt. When the
x
-axis is synchronized with the rotation and tilt axes, a spiral groove with a variable groove width is formed. In this case, servo control is synchronized with the three axes, and machining proceeds. In this study, we performed spiral groove shape machining through WEDM with the addition of 1-axis or 2-axis rotary axes, consequently verifying the machining accuracy. Moreover, two types of NC program were used for machining, direct input and CAM output, and the accuracy was compared. The results revealed that the groove width was wider in the direct input program. Therefore, there was a possibility that the wire could bend during machining and tilt along the direction of the apparent widening of the groove width. Thus, it is necessary to consider the deflection of the wire in WEDM with a rotary axis, which is different from the conventional one, to realize precision machining.
It has been proved that error compensation is an effective approach to improve machining accuracy of a machine tool cost efficiently. In this paper, the framework of an error compensation software ...system, which can realize software error compensation via numerical control (NC) programs reconstructing, is investigated. And the algorithms relating to error prediction are discussed in detail, such as positioning movement error compensation, linear interpolation movement, and circular interpolation movement error compensation. To realize the error compensation, NC program is reconstructed according to the predicted errors during virtual machining before it is fed to the actual machining. Two controlled machining experiments were carried out. The results show that error compensation methods via reconstructing NC programs can improve the movement accuracy of a computer numerical control CNC machine tool obviously.
In order to realize autonomous machining, it is necessary not only to automate the preparation tasks for machining but also to verify the machining results during the process. Therefore, this study ...realized the automation of planning for on-machine measurement, where measurement is conducted at the necessary time during the machining process based on process planning. Furthermore, when a machining abnormality is detected based on the measurement results, the proposed system automatically judges whether to stop machining or to re-machine the affected region. In the proposed system, measurement is conducted after the machining of a region that has an influence on the next machining process according to the association chart, which shows the subordination relationships of the geometrical constraints among removal volumes. If measurements indicate excess cutting, the system immediately stops machining because it is impossible for the workpiece to be modified. If measurements indicate incomplete cutting, the system re-machines the affected region and continues the machining process by recursively applying the NC program for the target removal volume. A case study was conducted in order to validate the proposed method of automated planning of on-machine measurement and re-machining. The result showed that the proposed system can automatically determine whether to stop or continue machining according to the measurement results.
One of the complex optimization problems arising in technical applications is the cutting path problem for CNC sheet metal cutting machines. This problem is to optimize the tool path for the CNC ...technological equipment when cutting a fixed set of parts allocated on sheet metal. The time of cutting process is one of objective functions for the optimization problem. This objective function depends on six parameters of cutting process: 1) cutting speed; 2) lengths of the cutting tool path; 3) speed of idling motion of tool; 4) length of idling motion; 5) number of piercings; 6) time of one piercing. When programming NC program, speed of cutting is defined by the user of the CAM (Computer-Aided-Manufacturing) system and considered as a constant. However, this is actually not the case. Consequently, the problem of exact calculation of objective function is arisen. In order to solve this problem, the correction coefficients for the cutting speed value defined by the user must been calculated. Obviously, these coefficients will vary for different thicknesses and grades of metal. The paper presents the results of investigates, which made it possible to find the functional dependences of the cutting speed for the CNC laser cutting machine (CO2) on the number of NC program commands for the following metal grades: 1.0114 (thickness Δ = 1-10 mm) and AWAIMg3 (Δ = 1-5 mm).The statistical materials of experiments were processed by using software "Mathcad". The received results show that the actual average value of cutting speed is monotonically decreasing function depended on number of NC program commands. In addition, the calculation of the actual cutting speed provides not only an accurate calculation of the value of the objective function, but also, as a result, the correct finding of the optimal tool path
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