Figure 2 Process chain result
The investigation strategy over appears that hobbing is best for green-machining, whereas the conclusion drawn for difficult- wrapping up of the gears is that sharpening works best. Producing adapt pounding isn't an choice since both gears on the shaft are as well near together, i.e.—insufficient space for the break of the pounding worm. In this occasion a unused or elective fabricating prepare for control gears does not however exist, due, maybe, to the moderately long holes between mechanical “breakthroughs” particular to a develop industry such as adapt fabricating. Without a doubt, equip fabricating development requires critical venture; e.g.—machine instruments. The most recent development in machining gears may be the capacity to sharpen fabricating parts with a near-grinding quality by means of “power honing.” Upon total assessment of the in- put handle chain, one more optimization potential can be found within the single fabricating handle. This may be accomplished by utilizing virtual generation strategies such as fabricating.
The approach for process optimization of gear hobbing begins with start- ing parameters—just like the process parameters and limitations of the actual process design. Potential limitations may be machine tool parameters such as maximumrevolutions-per-minute for the tool or workpiece spindle, or gear design restrictions like maximum-feed- mark deviations. Yet despite these default values and given restrictions, the soft- ware calculates every possible tool design capable of achieving these requirements.
The design of the gear shaft shows two power gears arranged close together, directly on the shaft; one gear is an interfering element for the manufacture of the other. The tool design is started with the general geometric boundary conditions for the tool. The results are no restrictions concerning the tool outside diameter for Gear No. 2 and a maximum tool outside diameter for Gear No. 1. A geometric calculation leads to a maximum outside diameter for Gear No. 1 of 45 mm. The outside diameter for Gear No. 2 can be chosen freely. The calculation is started with momentary process design (Fig. 2—red signs).For example, Gear No. 1:
It has a hob outside diameter of da = 45 mm; number of threads z0 = 1; and number of gashes ni = 9. In the chart the limits for variation are shown. The number of threads were varied from one to three; the hob diameter from 40 to 45 for Gear No. 1, and from 60 to 100 mm for Gear No. 2. The number of gashes is varied from 7 to 19, and 11 to 21.
The result revealed by the simulation is that the single-threaded variant is always the most productive. The reason—especially for Gear No. 1—is the lower helix angle for the thread at a lower number of threads. A higher helix angle results in a longer way of entry for the tool. Also, the larger the outside diameter process, the more productive the process. The larger, outside diameter of the single tooth is thicker and therefore more reconditioning cycles can be realized. In general, with the investment for one tool, more workpieces can be produced. As mentioned, the tool outside diameter for Gear No. 1 is limited by Gear No. 2. The maximum-outside-diameter is also limited by the machine tool, as both gears have to be produced in one step, on one machine tool.
The number of gashes should be as high as possible from the technological side. A higher number of gashes leads to lowergenerated cut deviations. From the productivity aspect a certain number of reconditioning cycles becomes possible, so the single teeth should not be too thin. Especially for Gear No. 1, this tool design—with number of gashes at ni = 11—is quite a low number when compared with Gear No. 2, with its number of gashes almost doubled at ni = 21. The remaining teeth will be quite thin, with the small outside diameter of da0 = 45 mm.
The simulation for Gear No. 1 leads to a tool design similar to the real-time process, so the use and functionality of the actual process design could be proven. In general, the simulation enables a very fast design of the tool by avoiding longlasting iteration cycles. In contrast to only experience-based tool design, the calculation has a robust basis.
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