2023年全國碩士研究生考試考研英語一試題真題(含答案詳解+作文范文)_第1頁
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1、3300 英文單詞, 英文單詞,1.7 萬英文字符,中文 萬英文字符,中文 5000 字文獻(xiàn)出處: 文獻(xiàn)出處:Brecher C, Brumm M, Krömer M. Design of gear hobbing processes using simulations and empirical data[J]. Procedia CIRP, 2015, 33: 484-489.Design of Gear Hobbing

2、Processes Using Simulations and Empirical DataC. Brecher, M. Brumm, M. KrömerAbstractGear Hobbing is one of the most productive manufacturing processes for pre-machining cylindrical gears. The process design as well

3、 as the tool selection is often based on experience or is limited to an iterative procedure. Existing methods for process and tool design are limited regarding the size of the gears and the process parameters.The objecti

4、ve presented in this paper is to support the process design by suggesting process parameters. To achieve this goal, a simulation for continuous gear hobbing was developed. By calculating planar intersections of transvers

5、e sections of both gear and tool, the generated chip geometries are determined. Due to the general approach of positioning tool and workpiece in the program, all continuous processes with defined cutting edges can be sim

6、ulated. The generated chip geometries are analyzed and characteristic values for each position of the tool are defined. Beside the chip geometries, other parameters such as working areas and the length of axis movements

7、are calculated too.Since the simulation process is time-consuming, it is not possible to calculate each hobbing process for different designs. Also, the simulation program cannot be implemented into the machine control d

8、ue to the needed computing capacity. Thus, a large amount of hobbing processes with varying gear geometries as well as different tools with the corresponding profiles are calculated in advance. By the use of regression a

9、nalysis, the results of these variations are transferred to approximation formulas afterwards, which are easy to calculate and to implement into other software products.To support the tool and process design, existing ho

10、bbing processes will be simulated with the help of the developed manufacturing simulation and the results will be stored in a database. By comparing the results of the approximation formulas with the values in the databa

11、se, it is possible to evaluate a given process.Keywords: Machining; Gear; Hobbing; Process; Design; Expert System; Simulation1. IntroductionFor designing gear hobbing processes, certain values are necessary that can be c

12、ompared and determined unambiguously. An established value for hobbing is the maximum chip thickness. Determining the chip thickness can be conducted according to different methods and formulas. A common and industrially

13、 as well as scientifically established way is the approximation formula for the maximum chip thickness according to HOFFMEISTER [18]. The approximation formula represents a simplified calculation that is based on empiric

14、al studies up to the module of mn = 4 mm. Investigations have shown that for gears of larger modules, the results according to HOFFMEISTER deviate from the actual chip thickness and underrate them [10].To define a reliab

15、le process design of large module gears, a dependable method for calculating the maximally occurring chip thickness in a process is necessary. For this purpose, a new formula for calculating the maximum chip thickness up

16、 to modules of mn = 30 mm will be created. In order to achieve this objective, a variation model will be set up. This allows determining approximation functions for different characteristic values by means of results of

17、a results of a geometrical penetration calculation. In recent past, HIPKE [17] developed a method for calculating process parameters for HSS hobs. The method is based on the average chip thickness and cutting length. Alt

18、ogether, the module range in these mentioned studies is mn < 10 mm. While HOFFMEISTER and HIPKE used gears up to mn = 4 mm, the formulas of MUNDT include gears with mn = 10 mm.Because none of theses studies provide a

19、comprehensive method for the full module range of currently used gears, the alternative is to design a process by the maximum chip thickness as well as experience. On this basis, an objective process design is nearly imp

20、ossible.2.2. Calculation Methods for the Chip Load in Gear HobbingTo calculate the chip thickness in gear hobbing, different methods can be used. A simple and effective option is the maximum chip thickness according to H

21、OFFMEISTER, (1).HOFFMEISTER approximates the real maximum chip thickness by exponential and potential functions with influence factors of tool, workpiece and process. These factors are the module mn, the number of workpi

22、ece teeth z2, the helix angle β, addendum modification factor xp, the axial feed fa, the cutting depth T as well as the number of gaps ni0 and the number of threads z0. The tool profile with pressure angle and the tool t

23、ip radius had been neglected in the investigations.Another method for calculating the chip thicknesses is using a process simulation software such as SPARTAPRO. The software was developed at the WZL of the RWTH Aachen Un

24、iversity, Fig. 2 [8].Fig. 2. Features of SPARTAproInput parameters are the geometrical information of the workpiece like module, number of teeth and outside diameter as well as the tool data and its profile geometry. Wit

25、h the given axial feed, a penetration calculation is executed and the undeformed chip geometries occurring in the hobbing process are determined. Afterwards, these geometries are analyzed and characteristic values such a

26、s the maximum and average chip thickness hcu,max and hcu,av, the specific chip volume V? and the maximum and average cutting length lmax and lav are calculated. The values are then displayed along the unrolled cutting ed

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