Real-time wear monitoring of hob cutters is of great significance to the quality and efficiency of gear hobbing. To achieve this goal, a strategy based on statistical analysis is proposed in this ...paper. First, vibration signals during the entire life cycle of a hob cutter are collected. Then, a feature iterative integration method is proposed to integrate the initial features of vibration signals. The integrated features have obvious stages, reflecting the different wear status of hob cutters. Next, a probability tabular cumulative sum control chart method is established to monitor the wear status of hob cutters in real time. Finally, the verification results of two different data sets prove the effectiveness and transferability of the proposed methods.
•Monitor hob cutter wear status in real time based on statistical analysis.•Collect vibration signals during the entire life cycle of a hob cutter.•Feature iterative integration method.•Probability tabular cumulative sum control chart method.
In the process of large module gear hobbing of high-order modification tooth profile, the cutting edge curve is different according to the variation of rake angle, which has a great influence on ...tooth profile accuracy. Thus the 2-degree envelope method is applied to the gear hobbing process to obtain the hobbing contact trace between the tooth surface and the base worm of the hobbing cutter. The cutting edge curve is calculated based on the different rake angles of the hobbing cutter. The shape and the slope of the cutting edge are analyzed, which provides the reference for the design and measurement of hobbing cutter edge. In the end, a modified gear profile is hobbed and measured to verify the above design method.
The aim of the work is to create a computer program in the 3D CAD system T Flex CAD allowing the creation of parametric models for the design and construction of a modular hob cutter for the selected ...gearing. The thesis includes the analysis of the problem of hob cutters for the production of spur gearing with an involute profile, the analysis of the initial surface and the shape of the tool cutting edge for the involute surface, the determination of the basic profile of the cutting edge of the hob cutter (geometry of the basic worm, geometry of the cutting edge) and the calculation of the design parameters of the tool. The individual calculations will be programmed in the 3D CAD system T Flex CAD, which will allow to generate a specific 3D model of the hob cutter based on the change of input requirements for the production of a given spur gear (module, engagement angle, tooth inclination angle), with the possibility of displaying the required tool in a 2D view in its base, normal and side planes, which will be in the form of a standard technical drawing. This paper presents the preparation (unification calculations, introduction) before the final version of the computer program for the creation of the parametric tool models.
Teeth hob cutter is widely used in cutting through hard rock. Cutter wear is inevitable during the strata with a large quartzite content, and excessive wear can lead to a decrease in tunneling ...efficiency and increase construction risks. Therefore, the importance of predicting the teeth hob cutter wear accurately and arranging the cutter change plan can never be overemphasized. In this paper, the rock breaking mechanism of teeth hob cutter was first analyzed. Based on this, combined with the theory of metal tribology theory, the wear prediction model for teeth hob cutters in high-content quartzite strata was derived. To verify the accuracy of the prediction model, the teeth hob cutter wear data for two cases were measured, which were collected from a cross-river shield tunnel project in Guangdong, China. Based on the observed wear data, it is found that the relative error of predicted wear and actual measurement was below 10%. The result shows that the prediction model can accurately reflect the real wear situation of teeth hob cutter in high-content quartzite strata.
High-speed dry hobbing is an emerging green technique for gear hobbing owing to its high productivity and environmental friendliness. However, severe friction occurs and heat instantaneously ...accumulates in the cutting region due to the adoption of high cutting speed and the lack of metalworking fluids, which causes serious hob wear. This investigation is concerned with the thermal performance and heat-loading quantitative method of hob cutter in high-speed dry hobbing. According to the multiple-edge and intermittent cutting behavior, the temporal dynamic characteristics of hob cutter are analyzed. Based on the complex 3D chip geometry produced in high-speed dry hobbing, the calculation method for heat-production (the amount of generated cutting heat) of hob tooth is proposed. Considering the coupling effects of heat conduction, heat convection, and heat radiation, the prediction model for heat-loading quantity (the bearing capacity of cutting heat) of hob tooth is developed. With the help of the developed method, the interrelation between the thermal performance of hob cutter and material removal volume, cutting conditions, coating material, respectively, are investigated. The predictive method developed in this work provides a methodology for process parameter optimization and hob cutter manufacturing of high-speed dry hobbing.
The article considers the technology of producing and processing of gear wheels. It provides some requirements for gear units, in particular, for gear wheels and their production. The paper analyzes ...the effectiveness of various techniques for cutting the gear teeth, as well as the effectiveness of various modern tools used for gear-tooth milling. The article mentions that it is possible to increase the effectiveness of the tool due to simultaneous processing of two or three tooth spaces. It requires the use of full-duplex (tandem) and triplex interlocking disk milling cutters. The results of these studies are confirmed by the description of a number of practical examples implementing these reporting provisions upon use of the equipment described in the paper.
The article shows the possibility of designing and manufacturing using multi-coordinate grinding and sharpening machines with CNC for workable worm mills for machining straight-slotted slots. Screw ...backing provides the necessary values of the rear side corners, and the ability of CNC machines to achieve the required accuracy and manufacturability of the tool. The lack of such tools consists in the increase of the diametrical sizes in comparison with the classically used ones. A positive effect when using the principles of screw backlash is the shaping of the cutting edges of the teeth in a checkerboard pattern, which significantly reduces the cutting forces. The use of techno-logical 3D models as a result of the design allows, at the design stage, to evaluate the arising design flaws and to make the necessary corrective actions into the initial data of the tool.
The algorithms of constructing geometrically accurate real computer 3d models are developed. The special feature of these algorithms is that they reproduce a technological process of manufacturing ...components. The examples of constructing spur and helical gear sets, bevel gears, Archimedes and globoid gear pairs are given. The accuracy of construction is estimated. The construction inaccuracy doesn’t exceed a part of μm, which enables one to use the models as computer samples for production accuracy control and the algorithms as a basis for programs of components production with the help of the programmed control machine tools.
The programs for implementation of the suggested algorithms are developed. The programs enable one to vary numerous model parameters and take into consideration teeth forms.
The applicability of programs for the analysis of geometric properties of the models is shown. The model of a worm wheel root surface is received. The kinematic surface formed in the globoid gear is examined. The author presents the model of milling of a gear wheel, where the impact of cutting parameters on the tooth form of a manufactured wheel is examined.
The models are constructed in the AutoCAD package. These programs are AutoLisp-based.
One of the most wide spread and efficient spline shafts manufacturing methods is their cutting by the means of generating process by hob cutters. In this case, hob cutter’s theoretical profile, ...taking in to account its inadaptability to manufacture, traditionally is approximated by the section(s) of one or two circles. In some cases this approach do not provides necessary accuracy or increase complexity of the manufacturing process. Alternative to the traditional approximation approach is theoretical profile substitution by the circle involute section. Absence of the methods for circle involute parameters evaluation makes this work relevant. There is approach suggested for this kind of substitution, based on equality of theoretical profile’s and substituting curve’s curvature radii in rated points. Methods and algorithms for substituting circle involute parameters and substitution accuracy evaluation are suggested. Given evaluation result shows more than 20 times higher approximation accuracy in comparison with the circle section substitution.
Spur-typed cutters with multiple cutting angles are important tools frequently used in the manufacture of many machine elements. Due to their complex geometry, the production of these cutters ...involves milling and several grinding processes. Such a complex manufacturing process, coupled with the need for expensive manufacturing tools, makes the cutters costly.
Undercutting is a phenomenon that causes weakness at the root of a gear. Engineers use shifted gears, modified tooth profiles, or changes in the pressure angle to overcome undercutting in gears. However, in this paper, by utilizing the undercutting phenomenon, a novel design of straight-sided hob cutter with multiple pressure angles is proposed for the manufacture of spur-typed cutters. With the simultaneous application of multiple pressure angles, this tool design concept significantly simplifies the manufacturing process. The effects of cutting angles, the degree of undercutting, and the width of the top land of the cutter are studied. The concepts and results proposed in this paper are beneficial as design guidance for tool designers and manufacturers.
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