In-situ freezing machining method for integrated thin-walled array structure

An in-situ freezing machining method for an integrated thin-walled array structure, wherein the method is realized based on an in-situ freezing fixturing system which is composed of a freezing device, an auxiliary device and a refrigeration system;

• the freezing device comprises an in-situ freezing fixturing shell and an insulation lid;
• the in-situ freezing fixturing shell has the function of heat preservation and is provided with a refrigeration tube inside, and refrigeration is realized through flow of liquid nitrogen in the refrigeration tube;
• and the insulation lid is used for heat preservation in the freezing process;
• the auxiliary device comprises clamps, a template and locators, wherein the template is arranged in the in-situ freezing fixturing shell, the locators and the template are used for locating a blank, and the clamps are used for clamping the edge of the blank;
• the refrigeration system comprises a liquid nitrogen tank, a nozzle and refrigeration equipment, wherein the refrigeration equipment is connected with the refrigeration tube in the in-situ freezing fixturing shell to control the flow of liquid nitrogen into the in-situ freezing fixturing shell so as to realize the control of the refrigeration power;
• and the nozzle is connected with the liquid nitrogen tank to realize local spraying of liquid nitrogen for machining;
• the in-situ freezing machining method comprises the following steps:
• step 1:
• in-situ freezing machining of cup array
• fixing the in-situ freezing fixturing shell on a machine tool platform, wherein the template, the clamps and the locators are fixedly connected in the in-situ freezing fixturing shell, and hoisting the blank onto the template, wherein the template is provided with a cup slot matched with the cup array, and the surface of the template is coated with a water layer;
• locating the side surface of the blank by the locators, and compressing the edge of the blank by the clamps;
• machining the cup array by a cutter:
• first, cutting off the area among cups in the cup array, and reserving edge material for cup array to form a cup array groove;
• second, carrying out rough machining and finish machining of the outer walls of the cups;
• finally, carrying out rough machining of the inner walls of the cups;
• cleaning up chips, filling water in the cup array groove and the cup array, covering the in-situ freezing fixturing shell with the insulation lid, starting the refrigeration equipment, and controlling the in-situ freezing fixturing shell to refrigerate and freeze the water;
• after freezing, removing the insulation lid, carrying out in-situ freezing machining of the inner walls of the cups in the cup array by the cutter, and during machining, keeping the refrigerating effect of the refrigeration equipment and the in-situ freezing fixturing shell all the time to prevent melting of ice caused by ambient thermal interference;
• after completing in-situ freezing machining, melting the ice and draining waste water;
• and during the process of cutting off the edge material for cup array, to avoid dents on the surface of the substrate caused by the clamps, removing the clamps and the locators, freezing the water layer into an ice layer under the refrigeration conditions of the refrigeration equipment and the in-situ freezing fixturing shell, clamping a workpiece by using the freezing stickiness of the ice layer, and completing cutoff of the edge material for cup array;
• step 2:
• in-situ freezing machining of cavity array
• hoisting and turning over, and inserting the cup array into the cup slot of the template, wherein the surface of the template is coated with a water layer;
• locating the workpiece by the locators, and compressing the workpiece by the clamps;
• machining the cavity array by the cutter:
• first, cutting off the area among cavities in the cavity array, and reserving edge material for cavity array to form a cavity array groove;
• second, carrying out rough machining and finish machining of the outer walls of the cavities;
• finally, carrying out rough machining of the inner walls of the cavities;
• cleaning up chips, filling water in the cavity array groove and the cavity array, covering the in-situ freezing fixturing shell with the insulation lid, starting the refrigeration equipment, and controlling the in-situ freezing fixturing shell to refrigerate and freeze the water;
• after freezing, removing the insulation lid, carrying out in-situ freezing machining of the inner walls of the cavities in the cavity array by the cutter, and during machining, keeping the refrigerating effect of the refrigeration equipment and the in-situ freezing fixturing shell all the time to prevent melting of the ice caused by ambient thermal interference;
• after completing in-situ freezing machining, melting the ice and draining waste water;
• and during the process of cutting off the edge material for cavity array, removing the clamps and the locators, freezing the water layer into an ice layer under the refrigeration conditions of the refrigeration equipment and the in-situ freezing fixturing shell, clamping the workpiece by using the freezing stickiness of the ice layer, and completing cutoff of the edge material for cavity array;
• at this point, the machining of the integrated thin-walled array structure is completed.