Plastic and nonmetallic article shaping or treating: processes – With step of making mold or mold shaping – per se
Reexamination Certificate
1998-11-18
2001-05-01
Fiorilla, Christopher A. (Department: 1731)
Plastic and nonmetallic article shaping or treating: processes
With step of making mold or mold shaping, per se
C264S234000, C264S629000, C264S645000
Reexamination Certificate
active
06224806
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a metallic mold for and a method of molding a cavity plate of an ink jet printer head, the cavity plate molded by the same and the ink jet printer head by using the cavity plate.
2. Description of the Related Art
There is an actuator of a head equipped in an ink jet printer, which expands and restores the capacity of many ink storing chambers formed inside the actuator using a piezoelectric element installed corresponding to each of the ink storing chambers, and which applies pressure to the ink inside the ink storing chamber. In this way, the actuator discharges the ink from an ink discharge or nozzle hole formed in each of the ink storing chambers to the external i.e., onto the recording sheet.
As one example of such an actuator, there is an actuator provided with: a cavity plate in which ink storing chambers and ink flow paths to supply the ink to the ink storing chambers are formed; and a nozzle plate which is fixed on the cavity plate and in which fine ink discharge holes are formed.
The cavity plate is produced by injection-molding ceramic such as alumina, and then applying a sintering process to it. In order to uniform the abilities to discharge the ink of all the ink discharge holes, the sizes of the ink storing chambers, the sizes of the ink flow paths and the sizes of the ink discharge holes are uniformed.
However, in the injection-molding process, since a metallic mold is used which is constructed by combining a pin member for forming the ink discharge holes and a corniform member for forming the ink flow paths, a gap is formed between the pin member and the corniform-formed member, resulting in one problem that a burr or flash is generated at the connection portion between these two members when the injection-molding process is finished.
Therefore, the burr or flash is removed by a polishing process. However, the sizes of the burrs or flashes are different from each other at the connection portions between the pin members and the corniform members respectively. Thus, it is difficult to uniform the sizes of the ink storing chambers and the ink flow paths, resulting in another problem that the abilities to discharge the ink of the ink discharge holes cannot be uniformed.
SUMMARY OF THE INVENTION
Given these circumstances, it is an object of the present invention to provide a metallic mold for and a method of molding a cavity plate, which can reduce the burr or flash in the injection-molding process, and a cavity plate which is produced by the molding method.
The above object of the present invention can be achieved by a mold for molding a cavity plate of an ink jet printer head. The cavity plate is adapted to be attached to a piezoelectric element member and has walls prescribing a plurality of ink storing chambers and a plurality of ink discharge holes. The mold of the present invention is provided with: a corniform block member including (i) a plurality of corniform convex portions to mold the ink storing chambers, each having an opening portion on a side of an attachment surface of the cavity plate to be attached to the piezoelectric element member, and (ii) a plurality of corniform concave portions to mold partition walls of the cavity plate for partitioning each of the ink storing chambers, the corniform convex portions and the corniform concave portions being alternatively disposed; and plurality of pin members to mold the ink discharge holes, which are continuous to the ink storing chambers such that the ink discharge holes have straight tubular portions respectively in predetermined lengths from the ink storing chambers to ink discharge tip portions at an ink discharge surface of the cavity plate on an opposite side of the attachment surface. The pin members include: (A) U shaped column portions, a cross section of each of which is in a U letter shape, to mold connection portions between the ink storing chambers and the straight tubular portions respectively, each of the U shaped column portions having (i) a half-cylindrical portion a cross section of which is in a half-circle shape and (ii) a prism portion a cross section of which is in a rectangular shape, at least whose length of one side is equal to a diameter of the half-cylindrical portion, the half-cylindrical portion and the prism portion being integrally formed; and (B) cylindrical portions to mold the straight tubular portions respectively. The U shaped column portions and the cylindrical portions are respectively formed continuously and integrally. The prism portion has an edge surface which contact with an edge surface of respective one of the corniform convex portions at a position corresponding to the connection portions in a condition where the pin members are assembled to the corniform block member.
According to the mold of the present invention, the corniform block member and the pin members are assembled to contact with each other. Then, when an molding process is performed in this assembled condition, the ink storing chambers are molded by the corniform concave portion such that each of the ink storing chambers has an opening portion on the side of the attachment surface. At the same time, the ink discharge holes are molded by the pin members such that each of the ink discharge holes has: the connection portion from the ink storing chamber to the straight tubular portion; and the straight tubular portion from the connection portion to the ink discharge tip portion on the side of the ink discharge surface. More precisely, by the cylindrical portions of the pin members, the straight tubular portions are respectively molded. And that, by the U shaped column portions of the pin members, the connection portions between the ink storing chambers and the straight tubular portions are respectively molded. At this time, in a condition where the pin members are assembled to the corniform block member, since the prism portion of the U shaped column portion has the edge surface, which contact with the edge surface of respective one of the corniform convex portions at a position corresponding to the connection portion, there is generated no or little gap between these contacted edge surfaces of the pin member and the corniform block member. Accordingly, after the molding process by using the mold of the present invention is performed, there is generated no or little burr or flash at the connection portion between the ink storing chamber and the ink discharge hole. Further, since the length of one side of the prism portion of the U shaped column portion is equal to the diameter of the half-cylindrical portion which is integrally formed with the prism portion, the connection portion and the straight tubular portion which are smoothly connected to each other can be obtained as the result of the molding process.
Consequently, such a cavity plate can be molded by using the mold of the present invention that the ink discharging abilities are uniform and stable over the plurality of ink discharge holes or ink nozzles.
In one aspect of the mold of the present invention, the edge surface of the prism portion has a width and a length equal to those of respective one of the corniform convex portions.
According to this aspect, since the prism portion of each of the pin members and the corniform convex portion of the corniform block are smoothly continued at the upper surface and the side surfaces of the corniform convex portion, after the molding process by using the mold of the present invention is performed, there is generated no or little burr or flash at the connection portion between the ink storing chamber and the ink discharge hole. Further, the connection portion and the ink storing chamber which are smoothly connected to each other can be obtained as the result of the molding process.
The above object of the present invention can be also achieved by a method of molding a cavity plate of an ink jet printer head. The cavity plate is adapted to be attached to a piezoelectric element member and has walls prescribing a plural
Inose Toshio
Kato Makoto
Brother Kogyo Kabushiki Kaisha
Fiorilla Christopher A.
Oliff & Berridg,e PLC
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