Singer Co. may pull out of the sewing machine business to concentrate on expanding its aerospace and military product lines, company officials said . . . A federal judge ordered Bankers Trust of New York to stop selling short-term securities on behalf of corporate clients . . . The combination of Lorimar Inc. and Telepictures Corp. has been renamed Lorimar-Telepictures Corp., the companies announced . . . Zymos of Sunnyvale, Calif., said its accountant, Touche, Ross & Co., is expected to qualify its opinion of Zymos' 1985 financial report "because of uncertainty that Zymos will have adequate financial resources." . . . Tyler Corp. of Dallas reported that it sold one of its operating subsidiaries, Thurston Aviation, to a group headed by professional golfer Arnold Palmer.