JPH0572878B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION A. Field of Industrial Application The present invention relates to a method of coupling a nozzle tube of an inkjet nozzle of an inkjet printing machine to a vibrating element (hereinafter referred to as a piezoelectric element) for operating the nozzle tube.

B. Prior Art There are various types of inkjet printing machines, one example of which is shown in FIG.

In this inkjet printing machine, a printing paper cassette 1 is set vertically in the printing machine, and printing paper 2 is taken out from this cassette and sent around a rotating printing head 3, where it is subjected to predetermined printing. , is sent further upward.

The print head 3 includes a plurality of ink jet nozzles 4 arranged radially outward from its center of rotation. Then head 3 rotates,
The nozzles 4 perform desired printing on the paper 2.

The inkjet nozzle 4 is, for example, a cylindrical nozzle tube 5 made of glass or plastic with a tapered jet tip, as shown in FIG.
A cylindrical piezoelectric element 6 is bonded to the outer periphery of the cylindrical piezoelectric element 6 with an adhesive 7 such as epoxy resin. Piezoelectric element 6
are on the outer peripheral surface and inner peripheral surface of the cylindrical piezo material 8,
Electrodes 9 electrically insulated from each other as shown in 9c.
a and 9b, and lead wires 10a and 10b are connected to these electrodes. The electrodes 9a and 9b are made of nickel metal or the like. When a voltage is applied between the electrodes 9a and 9b, the piezo material 8 contracts and ink is ejected from the nozzle tip.

C. Problems to be Solved by the Invention When solid ink is used, the nozzle tube 5 is heated, and therefore the epoxy resin adhesive 7 in contact with it is also heated. The adhesive 7 then expands when the printing press is in operation and contracts when it is not in operation.

However, in the conventional inkjet nozzle 4 as shown in FIG. 3, the epoxy resin adhesive 7 is directly attached to the electrode plating layer 9b on the cylindrical inner peripheral surface of the piezoelectric element 6, so that the adhesive 7 is When the temperature becomes low, the epoxy resin material of the adhesive and the piezoelectric element 6
Due to the difference in thermal expansion coefficient between the piezo material 8 and the piezo material 8 (the epoxy resin material has a higher low-temperature shrinkage rate than the piezo material), the electrode plating layer 9b is pulled by the epoxy resin adhesive 7 and peeled off from the piezo material 8. It may be done. This brings about various adverse effects on the performance of the piezoelectric element 6, such as a change in impedance due to a decrease in capacitance, a change in resonance frequency, and a decrease in mechanical strength.

D. Means for Solving the Problems The present invention aims to solve the problems of the prior art as described above.

To this end, the present invention provides a method for bonding with an adhesive between a nozzle pipe of an inkjet nozzle of an inkjet printing machine and a piezoelectric element that operates this nozzle pipe. The bonding between the adhesive and the piezoelectric element is achieved by applying a coating of a material with relatively low adhesion to the adhesive in the area and creating a bond between the coating and the nozzle tube with the adhesive. Provided is a coupling method that avoids deterioration of various properties of the piezoelectric element due to differences in thermal expansion coefficients between the piezoelectric elements.

The adhesive can be an epoxy resin, and the coating applied to the piezoelectric element can be a fluororesin (an example is known under the trade name "Teflon").

Since fluororesin has low adhesion to adhesives, it will not be pulled by the shrinkage of the adhesive, and therefore deterioration of various properties of the piezoelectric element can be avoided.

Hereinafter, a more specific explanation of the present invention will be continued with reference to FIG. 1, which shows a piezoelectric element configured such that the adhesive of the present invention can be carried out.

E. Embodiment In FIG. 1, parts corresponding to the parts of the conventional ink jet nozzle shown in FIG. 3 are indicated by the same part numbers as in FIG. 3.

As in the case of FIG.
Also in the figure, a cylindrical piezoelectric element 6 is installed around the outer periphery of the cylindrical nozzle pipe 5 of the inkjet nozzle 4, and is bonded to the nozzle pipe 5 with an epoxy resin adhesive 7.

The difference between the present invention and the prior art is that the piezoelectric element 6
In addition, a coating 11 of a material having low adhesion to the adhesive 7, for example, a fluororesin, is applied.

In the embodiment of FIG.
It is attached to the entire surface of the
It may be applied only to the area that is in contact with the piezoelectric element 6, that is, the area that covers the inner peripheral surface electrode 9b of the piezoelectric element 6.

F. Effects According to the present invention, as described above, a coating with low adhesiveness is applied to at least the area of the piezoelectric element that comes into contact with the adhesive, so that when a temperature change occurs, the piezoelectric element and the adhesive bond together. The properties of the piezoelectric element will not be deteriorated by the adhesive due to the difference in thermal expansion coefficient between the adhesives.

It should be noted that the embodiment of the present invention described with reference to FIG. Needless to say.

For example, although fluororesin is mentioned as the material for the coating 11, other materials having similar functions are known in the art, and the structure of the piezoelectric element,
The material of the adhesive, the manner of its adhesion, and therefore the overall configuration of the inkjet nozzle may also be different from that shown in FIG. 1 within the scope of the invention.

Furthermore, although the present invention has been described herein in connection with an inkjet nozzle, it may be useful in general to solve problems such as those related to adhesion between other materials or parts having different coefficients of thermal expansion. It will be understood that it can also be applied.

[Brief explanation of the drawing]

FIG. 1 is an axial sectional view of an inkjet nozzle in which a nozzle tube and a piezoelectric element are bonded together by the method of the present invention, and FIG. 2 is a perspective view of an inkjet printing machine.
FIG. 3 is an axial cross-sectional view of an inkjet nozzle bonded between a nozzle tube and a piezoelectric element using a prior art method. 4: Inkjet nozzle, 5: Nozzle pipe,
6: piezoelectric element, 7: adhesive, 8: piezoelectric material, 9
a, 9b: electrode, 11: fluororesin coating.

Claims (1)

[Scope of Claims] 1. A method of bonding between a nozzle pipe of an inkjet nozzle of an inkjet printing machine and a vibrating body element that operates this nozzle pipe by means of an adhesive, at least By applying a coating of a material with relatively low adhesion to the adhesive in an area adjacent to the nozzle pipe, and bonding with the adhesive between the coating and the nozzle pipe,
A method for joining a nozzle tube of an inkjet nozzle and a vibrating element, characterized in that deterioration of the vibrating element due to a difference in thermal expansion coefficient between the adhesive and the vibrating element is avoided. 2. In the method of combining claims 1,
A method for joining a nozzle tube of an inkjet nozzle and a vibrating body element, characterized in that the adhesive is an epoxy resin and the material of the coating is a fluororesin.