US Patent 7487783 Threading unit and method of threading

A threading unit for threading a thread through holes of a sheet-like flat member, including an upper block (2) and a lower block (3) mating with each other and each having formed therein a discontinuous vessel having apertures open on the respective mating surfaces. The upper and lower blocks, when joined together, have their discontinuous vessels connected to each other to complete a continuous vessel through which a thread is threaded. The upper and lower blocks are each split into a first upper piece (2A) and a second upper piece (2B) and a first lower piece (3A) and a second lower piece (3B), respectively, along the parting face. Each split has on its parting face a lengthwise cut half of the discontinuous vessel. The sheet-like flat member is sandwiched between the mating faces of the upper and lower blocks (2) and (3) with its holes coinciding with the apertures of the upper and lower blocks.