Improving the Performance of Hard-Alloy Deforming Broaches Using Modified Technological Lubricants
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S, POWDERS, PASTES
Improving the Performance of Hard-Alloy Deforming Broaches Using Modified Technological Lubricants S. Ye. Sheykina, *, I. Yu. Rostotskyia, **, V. T. Protsyshynb, V. V. Melnichenkoa, S. F. Studenetsa, D. V. Efrosinina, and Ya. V. Melnichenkoa a
Bakul Institute for Superhard Materials, National Academy of Science of Ukraine, Kyiv, 04074 Ukraine State Research Institute for Crude Oil Refining and Petrochemical Industry “MASMA,” Kyiv, 03680 Ukraine *e-mail: [email protected] **e-mail: [email protected]
b
Received September 11, 2019; revised September 30, 2019; accepted October 5, 2019
Abstract—The performance of hard-alloy deforming broaches when machining shaped holes in parts made of 38Kh2MYuA steel by deforming broaching was increased. This result was achieved by using the developed effective technological oil and antifriction titanium nitride coating on the working surfaces of the tool, which decreased axial pulling forces and yielded low roughness values. This approach ensures processing without gripping under normal contact pressures up to 4 GPa. Keywords: process oil, deforming pulling, gripping, running ability DOI: 10.3103/S1063457620040085
INTRODUCTION In Ukraine, tubular products with both a smooth hole surface and with screw threads are currently of great demand. Therefore, the task of developing an industrial technology for shaping and strengthening the inner surface of such products is urgent. The dimensions of parts can vary over a wide range: length can be up to 6 m, and the hole diameter can vary within 5–125 mm or more. The existing technological processes of shaping the inner surface of this type can include cutting operations (boring, countersinking, cutting broaching), plastic deformation (radial forging, deforming broaching (DP, mandrel), and electrochemical processing. Taking into account that the length of products can reach several meters, their blade processing is rather laborious, and the dimensions and cost of the tool (cutting broaches) are significant. The radial forging process requires the use of expensive high-precision equipment that is not produced in Ukraine. The Lothar Walter, Shillien, Hart, Weatherby, and Bergara Barrels Factory companies use broaching to form screw grooves in holes (Fig. 1). This technology yields a significant strain hardening, increases the resource of the finished product, and provides high productivity, a high coefficient of material utilization, and energy saving. The implementation of this technique does not require the use of special equipment. Its use in manufacturing tubular products with both a round hole and a shaped one would solve many existing problems [1]. Construction alloyed steels 38Kh2MYuA or 38KhN3MFA (HRC 28–32) are used for the manufacture of such products. Figure 2 shows the contact pressure in the zone of interaction of the tool with the workpiece surface in the broaching of a 38Kh2MYuA workpiece with the wall thickness of 10 mm and with a hole 40 mm in diameter, calculated by the finite element method using the A
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