Improvements in or relating to sewing machines having lubricated needle bars, especially high-speed industrial sewing machines

摘要

689,672. Sewing machines. DURKOPPWERKE AKT.-GES. July 16, 1951 [July 17, 1950], No. 16774/51. Class 112. [Also in Group XXXIV] In order to prevent transfer of lubricant from the needle-bar to the work, the needle-bar is made hollow, the bore communicating with the outer surface at the lower end, and forms one element of a pump arranged to create a reduction of air-pressure in the needle-bar bore to draw oil into it. In the embodiment shown, the upper bearing 1 for the hollow needle-bar 2 is closed at the top so as to form a pump with the needle-bar, the outlet of the pump being through a lateral bore in the bearing pin of the crosshead 8, communicating with the needlebar bore, and radial holes in that pin and the eye of the link 9; the holes in the pin and eye coincide during the upstroke of the needle and are out of register during the down stroke to create a suction to draw into the needle-bar bore through radial apertures any oil collecting in a circumferential groove 3, this oil passing up through wicking in the needle-bar bore and being discharged into the head of the machine. The upper end of the lower needle-bar bearing 1SP1/SP is sharp-edged to scrape off most of the oil on the needle-bar surface.