The article describes a new method for integrated processing which combines high-energy heating by high frequency currents (HEH HFC) and abrasive grinding. Research clearly showed that implementation of integrated processing may lead to 2 . . . 2.5-fold increasing of the processing performance. It was established experimentally that the proposed integrated treatment results in increasing of the microhardness and the level of residual compressive stresses in the surface layer. This increases the contact-fatigue strength of steel parts up to 10% . . . 16%.
Purpose: In the present work, different combinations of fits and accuracies, in relation to the profiles of mating parts, have been analysed in order to assess the degree of the engagement of transmissions that contain intermediate rolling elements. The aim of this work is to determine which fits have decreased accuracy, but nevertheless provide a minimum manufacturing clearance for the transmission engagement in order to reduce the cost of parts production. Methods and materials: Considering the normal probabilistic distribution law in relation to the obtained dimensions of the manufacturing equipment, a combination of fits were selected using the incomplete interchangeability method, taking into account the peculiarities of the cycloid engagement in transmissions with intermediate rolling elements (IRE). Results: Having studied various combinations of fits of parts that are engaged in transmissions with intermediate rolling elements and a free cage (IREFC), a combination of fits for a “ring, rolling-element cam” were determined, in which a technological clearance of 3 µm is formed in the engagement. At the same time, cycloid disk profiles are manufactured according to the 9th tolerance grade, which reduces the laboriousness and cost of the production. Discussion. When reducing the manufacturing accuracy of cycloid disks, it is possible to obtain both very ample clearances and significant negative allowances. For example, having manufactured a ring with the H9 fit, rolling elements with h6 and a cam with js9, the maximum manufacturing clearance can reach 0.086 mm, while the clearance limits vary from 0.025 mm to 0.061 mm. Additionally, if mating parts are manufactured using a combination of K9-h6-js9 fits, a negative allowance varying from 0.014 mm to 0.026 mm will emerge in the engagement. Both described cases are unacceptable because both ample clearances and large negative allowances will negatively influence the working capacity of the mechanism. However, it is possible to select a combination of fits using the 9th tolerance grade of the basic parts, by which the parts will contact in the range from a small negative allowance of 1 µm to a clearance of 3–4 µm. Furthermore, if this is considered, taking into account the machine settings, it is possible to obtain parts according to the 9th accuracy tolerance grade and, at the same time, provide a clearance in the engagement that is almost equal to zero. Moreover, such a combination of fits is relevant for any transmission with IRE. This is a positive result because it reduces the laboriousness when manufacturing parts and, at the same time, provides high accuracy of the mechanism. Conclusions: It has been established that when lowering the accuracy of manufacturing transmission parts with IRE, both clearances and negative allowances may occur in the engagement, depending on the combination of fits. At the same time, it is possible to select such a combination of fits, by which the parts manufactured according to the 9th tolerance grade, will provide almost zero clearance of the engagement of the transmission. In this way, it is possible to reduce the cost of manufacturing the parts for gears with intermediate rolling elements and, at the same time, maintain a high accuracy of the transmission mechanism.
Abstract. The paper examines the process of surface hardening of steel 45 with the help of high energy heating by high frequency currents with simultaneous shower water cooling. We theoretically justified and experimentally proved a possibility of liquid phase forming in the course of heating not on the surface, but in the depth of the surface layer. IntroductionSurface hardening of steel workpieces with concentrated energy sources is characterized by high rates of heating (tens of thousands of degrees a second) [1 -7]. Under these conditions the heating of steel is carried out up to the melting temperature for the completion of the austenitizing process. While using the surface sources of heating (laser or plasma) the maximum values of temperatures are definitely observed on the surface of material proper [8,9]. But for three-dimensional energy sources (electron beam, high frequency currents) this fact is not obvious. It is explained, first of all, by the physical nature of a three-dimensional source, i.e. by the law of energy distribution throughout the depth of a heated layer. A possibility of melted metal micro-volumes to form in the depth of material at heating with an electron beam in the atmosphere is shown in paper [10]. Ledeburite structure typical for the heat treatment of cast irons was registered in these areas during surface hardening of hypereutectoid steel.At heating of steels in air medium by a concentrated electron beam the emitted energy distribution in material is similar to that of high energy heating by high frequency currents (HEH HFC) [11]. In this case during the surface hardening with HEH HFC one can also expect a possibility of liquid phase local volumes emergence in the depth of material.The objective of this research is to determine the most heat-stressed layer during high energy heating of steel workpieces by high frequency currents with simultaneous shower cooling.
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