US 4,675,043 AGranted

Apparatus for manufacture of tubular elements for ink jet printers

AssigneeIng.C. Olivetti & C., S.p.A.

InventorsRenato Conta, Remo Rocchi, Alessandro Scardovi

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Abstract

The apparatus for manufacturing the ink jet glass tubes includes a vertical mandrel which receives the tubes one at a time from a feeder and rotates them relative to a pair of gas nozzles for their heating. The tube is heated in an axially limited intermediary zone so as to form an hour-glass shaped profile. The profile of the tube is scanned by a television camera which generates two signals indicative of the internal diameter. These are compared electronically with a stored indication of the desired diameter and the two nozzles are rotated into an inactive position when this diameter is reached. The tube is cut along a plane so as to make the profile of the nozzle coincident with a reference profile by a device including an optical device connected to a cutting wheel to permit comparison of the hour-glass profile of the element with the reference profile. The severed end of the tube is then lapped and covered with a non-wettable material. The tubular element is bonded within a piezo-electric transducer, by locating the latter partially in a chamber, after fitting it over the tubular element, while a pump draws an epoxy resin through the chamber and into the space between the transducer and the tubular element.

An apparatus for shaping a nozzle of a tubular ejector of an ink jet printing device, the ejector being shaped from a tubular element having a diameter substantially equal to the diameter of the ejector and formed of a transparent material which can be brought to a viscous state by heating, the nozzle being formed of half an hourglass portion having a capillary orifice, said apparatus comprising:

a vertical axis, rotary mandrel having an axial cavity operable for gripping an upper end of one of the tubular elements;
means disposed above said mandrel for individually gravity feeding the tubular elements into the axis cavity of said mandrel;
a bearing element having a horizontal plane located beneath said mandrel in a fixed axial stopping position for stopping the axial movement of the tubular element fed into said mandrel, said bearing element capable of moving away from the stopping position to a position for allowing the tubular element to drop gravitationally from said mandrel;
a plurality of heating means equiangularly spaced about the vertical axis of said mandrel, said heating means being arranged to effect localized heating in a limited zone between said mandrel and said bearing element to bring material constituting an intermediate portion of the wall of the tubular element located within said zone to a viscous state while the tubular element is rotated by said mandrel, said heating means being located in a position to define a portion of the tubular element below said zone having a weight sufficient to cause transverse stresses on the tubular element which combine with gravitational forces to progressively reduce the cross-sectional area of the tubular element within said zone and form the hour-glass portion;
optical detector means sufficiently located with respect to said heating zone for detecting variations of luminance of the visual field in said zone during heating, and generating a measurement indicating when the inner diameter of the tubular element in a transverse plane of said zone reaches a desired value;
and
means for stopping the heating within said zone when the desired inner diameter of the tubular element is attained, said means controlled by said optical detector.

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Abstract

Claims7