Method of making a printing head for an ink jet printer

Abstract

The method of making a print head of the type that includes a piezoelectric transducer positioned within a metal housing having an annular channel in its inner surface that is sealed by a thin metal diaphragm to form an annular ink chamber. The transducer is in mechanical engagement with the inner surface of the diaphragm. The sudden removal of a voltage applied to the transducer expands the disk to reduce the volume of the ink chamber, rupture the meniscus, and force a droplet of ink from the printing orifice. The housing is formed with an internal taper which permits a groove to be cut readily either by a casting or by a tool entering from the larger end of the central opening in the housing. An aluminum mandrel is tapered to match the taper on the inner surface of the housing and provided with an annular groove that corresponds to the groove in the housing. The mandrel is plated with nickel that will later form the diaphragm. The housing and mandrel are then plated with indium. The mandrel is then forced into the central opening of the housing and subjected to ultrasonic energy, or maintained under pressure at an elevated temperature, to form a cold weld. The mandrel is removed by dissolving it in a caustic solution.