In this paper, we take the vertical tool changer device as an example to study the reliability of the manipulator in the heavy tool case. Firstly, introduce the structure of the vertical tool changer ...device, and do a simple instruction for the functions of the main components; Secondly, analyze the mechanical properties of the manipulator theoretically, find out the maximum force in the tool changer processing and build a virtual platform of the automatic tool changer to simulate the processing and test the performance of the tool changer; Finally, analyze the performance of the manipulator by finite element method in the heavy tool case. The analysis result shows that the maximum stress is less than the allowable stress: when the manipulator grasps heavy tool, so it is safe in the tool changer processing.
In order to reduce non-cutting time and improve machining efficiency, the macro program of automatic tool changer (ATC) has been designed firstly, which was based on the macro theory and parameter ...settings. Then, the machining simulation environment of the automatic tool changing was established, based on which, the digital simulation of automatic tool changing process is realized by mapping of the practical changing tool process in the virtual machining environment. The simulation results effectively verify and improve the macro program performance.
To enhance machining efficiency, tool change time has to be reduced. Thus, for an automatic tool changer attached to a machining center, the tool change time is to be reduced. Also the automatic tool ...changer is a main part of the machining center as a driving source. The static attributes of the automatic tool changer using the commercial code, ANSYS Workbench V12, were tried to interpret. And the optimum design of automatic tool changer arm was proposed by performing the multi-stage optimum design. The shape optimization of the automatic tool changer was proposed and the result was verified to obtain acceptable improvements. It is possible to obtain an optimized model in which the maximum deformation, maximum stress, and mass are reduced by 10.46%, 12.89% and 9.26%, respectively, compared with those of the initial model. Also, the results between conventional method by the design of experiments and proposed method by the multi-stage optimum design method were compared.
The discrete systems in a machining centre, such as the automatic tool changer and automatic pallet changer, play important roles in improving productivity in machining automation. However, system ...configuration and sequential logic programming still require considerable skill and are handled on a case by case basis. A simulation-based verification environment could improve system performance, reduce ramp-up time and cost, and avoid false setup and system deterioration. In this study, we developed a simulation model as well as a visualisation of a disk-type automatic tool changer (ATC) to assist with ATC mechanical design and PLC logic verification. Our simulation model was based on an object-oriented modelling approach, and consisted of model blocks corresponding to essential components such as the motor, gear set, cam-follower, and proximity sensors. We tested the model in a real-time simulation that used the software component of an actual machine tool controller in the simulation loop to evaluate the real-time calculation performance and the feasibility in a real application such as logic and configuration verification. The results related to the feed drive motion with limit sensor action in the ATC turret operation showed that our approach was practical and met the real-time requirements.
The main features of the tool magazine drive in a type of vertical machining centers with computer numerical control are analyzed. On this basis, an algorithm for optimal tool position searching has ...been presented. A control device using Verilog hardware description language has been developed. The approach offered achieves autonomous control of this drive and reduces the requirements to the respective CNC system. Experimental results of the synthesized control device and practical applications of the implemented tool magazine drive are presented and discussed. This research and the results obtained can be used in modernization of the considered machine tools.
The papers deals with description of a generating method for structural configuration of machining centers, considering in detail a vertical machining center with three axes. Starting from a ...structural configuration of an existing machining center the basic structural configuration is established. A tree-graph corresponding to this structure is generated. It consists of a sequence of structure elements connected by joints. By combining the elements and joints, one can obtain all possible variants of configurations. Applying some criteria the optimum variant is obtained.
The paper examines the minimisation of the tool change waiting time of numerically controlled machine tools equipped with rotating tool magazines and buffering tool changers. The tool order in the ...various magazine operation concepts is optimised with the primary objective of minimising waiting time caused by tool change and magazine rotation. Other issues such as the total tool magazine travel are also considered. Numerical experiments are conducted and an industrial case is analysed. It was found that the optimisation is most beneficial if the magazine is large, cutting times short and the tool usage frequency distribution non-uniform. Waiting time savings of 50%–70% are typical compared to the case of random tool order in the magazine. A considerable reduction of idle times and magazine travels was reached in the industrial application described. The corresponding problem in the case of unbuffered tool change was studied in the earlier Part 1 of the paper.
This paper proposes a novel leakage flux cancellation technique suitable for series-parallel combined resonant circuits with asymmetric rotary transformer used for ultrasonic spindles drive. An ...asymmetric rotary transformer is utilized in the ultrasonic spindle in order to realize automated tool change. However, an asymmetric rotary transformer is likely to occur much leakage fluxes in secondly core due to asymmetric core structures. This large leakage inductance affects a drive circuit using a series-parallel combined resonant circuit, and the resonant characteristics in the drive circuit become very steep. In this state, the resonance circuit does not realize the desired function when the drive frequency fluctuates or the error of resonance parameters occurs. Therefore, this paper proposes a novel leakage flux cancellation technique used for ultrasonic spindle drive. The effectiveness of the proposed method is discussed from the theoretical analysis and experimental test.
A tool magazine and automatic tool changer (ATC) is used to store and change tools in a machining center, which plays an important role in automatic manufacturing. Therefore, the stability and ...reliability of a tool magazine and ATC are very important to a machining center. Failures of a tool magazine and ATC would increase the maintenance time and repair cost. So the operational reliability for a tool magazine and ATC becomes a hotspot research. The tool-pulling force of a tool magazine and ATC would be obvious when the tool changing arm draws a tool holder out of a tool pocket and the tool-pulling force can reflect the degree of the lock springs failure which is one of the main reason for tool falling failure. To calculate the operational reliability of springs in the ATC and get ATC running status, the mathematical models between tool-pulling force and parameters of springs are built. Then, tool-pulling force test is conducted by using a special device and the test data are fitted by the linear equation. According to the correspondence between the mathematical models and coefficients of the linear fitting, the loading of springs is obtained. Then, the operational reliability of the single spring is calculated by the stress strength interference model and the operational reliability of springs set is calculated by reliability calculation method of series system.
The purpose of this paper is to generate all possible design configurations of machining centres with tool change mechanisms. A methodology is proposed for synthesizing the mechanisms of machining ...centres with required topology and motion characteristics. Machining centres with tool change mechanisms up to eight links are synthesized. For machining centres with a two degrees of freedom table, the mechanisms with seven and eight links have three and 17 different design configurations, respectively. The results of this work provide a systematic approach for synthesizing spatial open-type mechanisms with motion requirements.
