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Fig. 11. Experimental set up.
Fig. 12. Experimental validation of stability lobes in the SVDH mass-spindle speed plane.
5. Conclusion
The use of SVDH to drill small-diameter deep holes enables pro-ductivity to be improved by eliminating the retreat cycles. The main difficulty is to choose the adequate cutting parameters to obtain self-excited vibrations which enable the fragmentation of the chips.
To achieve this goal, a dynamic model of the global system composed of spindle–SVDH–tool is developed. The structural com-ponents of the system were modeled using a specific rotor-beam element, taking into account the speed-dependent gyroscopic effects and centrifugal forces. The interface models were identi-fied by the receptance coupling method and then integrated into the global spindle–SVDH–tool model.
Adequate cutting conditions are determined by integrating the model-based tool tip transfer function into an analytical chatter vibration stability approach. Specific stability lobe diagrams are elaborated, taking into account the effective dynamic properties of the studied system. The torsional–axial coupling of the twist drill is modeled based on Bayly’s approach and integrated into the overall system dynamics in order to investigate drilling stability. The stability lobes established indicate modifications of self-excited operating zones, allowing increased drilling operation productivity for specifics combinations of SVDH rigidity and mass.
The results of such a stability analysis for the model are compared to experimentally determined stability boundaries for validation purposes. Taking into account the torsional–axial cou-pling of the drill allows refining the stability prediction of the global system during a drilling operation.
Engineering Design of A Gang Drilling Machine Equipped with Jig and Fixtures to Make A Prototype Machine in Birdcage Production
Eddy Widiyono, Winarto, Rivai Wardhani, and Liza Rusdiyana
Abstract—This paper is dealing with the engineering design of a gang drilling machine with jig&fixtures to make a prototype machine. This effort has been done in order to solve the problem which aroused in small business enterprises producing birdcages. The problem was how to minimize the production time in making a lot of holes that have same distance and straightness. Hopefully, the prototype machine can help the small business enterprises to increase their production rate.The design engineering process has been carried out by variant approximation on dowel pin modular fixtures in order to simplify fixtures design. CAD CAM software has also been used as fixtures synthesized method including geometric analysis and three dimensional fixtures assembling. The resulting prototype machine can be well operated and based on the running test, it can be concluded that the greater the motor rotation the greater the power needed. As for teak wood, at 250 rpm motor rotation the power needed is 26.5 watt, and at 400 rpm the motor needs power of 43.6 watt while at 600 rpm the motor needs power of 600 watt. The power consumption is also depends on the type of material, the better the mechanical properties of the materials, the higher the power consumption. For cast iron, the 400rpm motor rotation needs power as high as 569.7 watt. This prototype of gang drilling machine needs power of 350 watt to make five holes on teak wood while ordinary drilling machine needs total power of 1350 watt.
Keywords—birdcage, fixtures, gang drill, jig, small business
I. INTRODUCTION
The management of fixtures system in machining remain relatively stagnant especially the progress of technology development. This condition governs to the needs of scientifically-based management of model formalization which can give significant contribution to the development of fixture systems [1].