Analysis of tilting table with parallel kinematics

The paper deals with the investigation of a workpiece moving unit with parallel kinematics. The subject of the study is the choice of the positions, installation location of actuator of the workpiece moving unit, table, how it affects the operation of the structure. This study is extremely important because the position of the actuators determines the functionality of the structure, i.e., we can predefine the position of the actuators so that the system can perform the desired movements. The possible installation locations of the actuators will be determined using combinatorics. Screw theory will be used to calculate the degree of freedom of the mechanism.

State of the art of DSRW test equipment subjected to side loads and equipment proposal for static testing at natural scale

Dry Stone retaining walls, DSRW, are low-cost traditional structures made of stones aimed to stabilize, support backfill and avoid soil erosion. They have massively been used as foundation of dwellings by vulnerable population located in the steeped hills surrounding some Latin-American cities. These walls are built following ancient techniques that are neither well studied nor formally established. Millions of people live in these conditions in seismic zones generating a high-risk situation. Experimental and numerical studies are needed in order to evaluate the reliability of low-cost DSRW and to validate or improve traditional techniques. The objective of this ongoing research is to design and construct a full-scale testing equipment to assess DSRW performance against lateral out-of-plane seismic forces. The methodology consists in the following steps: (1) Review of state-of-art of experimental testing of DSRW, (2) Analysis of failure modes of similar constructions (3) Conceptual and structural design of optimum full-scale testing equipment, (4) Construction planning (blueprints and budget) and (5) Construction and operation. Testing equipment found in technical literature can be classified into two groups according to the applied force: dynamic and static. Forces in dynamic tests are the result of acceleration imposed to the specimen, e.g. shaking tables and centrifuge machines. Forces in static testing are applied by hydrostatic pressure, lateral earth pressure, and specimen´s weight. Applied forces in dynamic tests simulate seismic forces well. On the other hand, it is a high cost solution and requires very specialized staff for operation and maintenance. Static alternatives are more affordable but seismic forces are roughly simulated by static forces. In this work a tilt table is proposed to test full-scale specimens. In this test, the specimen is built in a horizontal table that is slowly rotated. In this way, a static out-of-plane force acts in each particle of the specimen. The magnitude of the total force is the specimen´s weight multiplied by the sin of the rotating angle. Static test results could be conservative but they could give a good approach to understand DSRW damage accumulation process and failure. Two equipments were proposed: (1) tilting table for monotonic static test and (2) tilting table for cylic test. We compare costs, required area, construction feasibility, and operation manageability. We conclude that both of them are straightforward solutions to assess DSRW performance against out-of-plane lateral forces.

Effect of tilting angle on the dynamics of tilting table driven by worm and worm wheel

The dynamics of tilting table behaves differently during five-axis machining due to the constant changes of the position of its center of mass which leads to different forces acting on parts of the transmission system. In this research, the lumped parameter method is used to model the dynamics of tilting table driven by worm and worm wheel in the tilting direction, where the varying stiffness of the transmission system at different tilting angles is considered. The impact testing experiments of tilting table system with tilting angles from 0° to 90° are also performed to verify the analytical model. The results from sensitivity analysis show that the three stiffnesses have a great effect on the variation of system natural frequency in the tilting direction, including the equivalent tangential meshing stiffness of worm and worm wheel, the torsional stiffness of worm wheel shaft, and the axial stiffness of worm supporting bearings. Moreover, the variations of system natural frequency with the three stiffnesses at different tilting angles are further investigated.

Research on Rotary and Tilting Table Five-Axis Milling Post-Processing Software Star-Fpost

Based on the MIRON UCP800 rotary and tilting table five-axis machine, this paper studies the mathematical model of Five-Axis machining and derives the algorithm formula of Six-Coordinate axis vector into five-axis AC rotary and tilting table. The Post-Processing process of turning the source file to the machine tool path code is fulfilled by using coordinate transformation matrix; with reading the cutting location file line by line, a dedicated five-axis milling post-processing software through adapting the Keyword-Triggered method is developed by using object-oriented program in the paper. First completing construction of Five-Axis machine tools mode in the VERICUT simulation environment, then manufacturing the whole shaft by ternary simulation of impeller machining in NX, and the simulation results shows that the function of Post-Processing software Star-Fpost. The software can provide the actual processing of information for MIKRON UCP800 five-axis machine tools.