Method for generating optimal straight-line enveloping surface of free-form surface blade

Abstract

The invention discloses a method for generating an optimal straight-line enveloping surface of a free-form surface blade. The method for generating the optimal straight-line enveloping surface of the free-form surface blade comprises the steps of (1) carrying out offset on the blade, carrying out preprocessing on the blade through the method that shortening is carried out and then tangential extending is carried out so as to obtain a curved surface to be enveloped; (2) cutting out the curved surface to be enveloped through a plurality of planes to obtain free-form surface section lines, wherein the planes are arranged at equal intervals and are perpendicular to the axial direction of an impeller or a blade disk; (3) according to the free-form surface section lines, generating optimal enveloping straight lines of the free-form surface section lines through the residual allowance maximum minimizing method according to the position relation between endpoint connecting lines of the free-form surface section lines and the free-form surface section lines, and concavity and convexity of the free-form surface section lines; (4) using two endpoints of each of all the optimal enveloping straight lines as data points to generate two splines, using the two generated splines as directrixes to generate the optimal straight-line enveloping surface of a free-form surface. When the optimal straight-line enveloping surface generated through the method for generating the optimal straight-line enveloping surface of the free-form surface blade serves as a tool drive surface, uniformity of the working allowance can be ensured, the overcutting phenomenon can be avoided in the process of machining, and efficiency of rough machining is remarkably improved.

Description

technical field [0001] The invention relates to a method for generating an optimal ruled envelope surface of a free-form surface blade, belonging to the technical field of numerical control processing. Background technique [0002] With the development of CNC machining technology, a large number of free-form surface parts are used in aerospace, automobile manufacturing, shipbuilding and many other fields. The free-form surface components of these complex products have very high requirements on their manufacturing technology, especially for complex free-form surfaces with multiple constraints such as blades, and their efficient processing technology has become a hot and difficult research point in recent years. At present, for the rough machining of such parts, the method of plunge milling is adopted. Plunge milling is an efficient rough machining method. During machining, the tool is fed along the direction of the tool axis, and the cutting edge at the bottom is used for dr...

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Problems solved by technology

In the existing published literature "Four-coordinate Efficient Slotting and Plunging and Milling Process Method for Open Integral Blisk" and "Integral Impeller Plunging and Milling Rough Machining Algorithm", the former adopts the ruled envelope surface generation method based on the minimum area principle to generate The straight-grain envelope surface of the blade is used as the plunging and milling boundary. Although it can ensure the maximum material removal, the machining surface may leave an uneven allowance, resulting in a large difference in the allowance during the subsequent semi-finishing and finishing machining, which affects the parts. Surface processing quality; the latter adopts the method of generating the ruled envelope surface based on the principle of least squares to generate the ruled envelope surface of the blade as the plunging and milling boundary. Although it can ensure a relatively uniform machining allowance, it may Overcut will occur, which will lead to insufficient allowance for subsequent semi-finishing and finishing machining, and even lead to scrapping of parts in severe cases

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