JPS6348714B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an inkjet nozzle and, more particularly, to a new and improved method of manufacturing an inkjet nozzle in a computer-coupled inkjet printer.

Generally, the inkjet nozzle in the head of an inkjet printer is constructed with fine holes having a diameter of about several tens of microns. It is desirable that the inkjet ejected from this inkjet nozzle be in a laminar flow state without turbulence. Therefore, this inkjet nozzle has a straight part with a constant diameter at the tip of the nozzle, and a monoplane hyperboloid shape toward the rear. A shape with a wide expanse is considered ideal.

Conventionally, as shown in Figure 1a, the conventional method for manufacturing such an inkjet nozzle is to use ruby, sapphire, etc. as a base material, and then polish it to form a spherical surface with a radius of curvature of about 100 microns. A is provided, then a microscopic hole b of several tens of microns is formed using a laser beam, etc., and finally, a thin wire is inserted into this microscopic hole and the inner surface of the microscopic hole b is finished in the presence of diamond abrasive grains, etc. A method is known, but in this method, when forming the microscopic hole b using a laser beam, the central axis of the laser beam tends to oscillate with respect to the central axis of the spherical surface a, and the microscopic hole b
When finishing the inner surface, there was a problem that the periphery easily chipped off.

In addition, a method of forming micropores by electroforming is known, but when this method is used, fine depressions extending radially on the inner peripheral surface of the micropore are formed as shown in Figure 1b. There was a problem in that a striped pattern consisting of the grooves c was easily formed, and it was almost impossible to form a constant diameter area (straight part) for forming a laminar ink jet, and even if it was possible, it was extremely short.

Furthermore, as another method for manufacturing this inkjet nozzle, as shown in FIG. There are known methods such as forming micropores (e) and forming micropores by etching from both sides of the base material as shown in Figure d, but in this case, the reproducibility of the nozzle shape is poor and productivity suffers. The problem was that it was inferior.

Moreover, the shape of the micropores obtained by the above-mentioned conventional nozzle manufacturing method is far from the ideal shape for the above-mentioned inkjet nozzle, and therefore it is difficult to create a steady inkjet. It was hot.

The present invention provides a new and improved method for manufacturing an inkjet nozzle having a desired shape that could not be achieved using the conventionally known methods described above. A concave portion whose depth reaches at least the thickness of the sheet and extends upward from the bottom in the shape of a monoplane hyperboloid is formed, and then the convex portion protruding from the back side of the sheet is removed by grinding to form an orifice with fine holes. Step of obtaining a backsheet, b. Forming micropores in the metal sheet with a constant diameter equal to or slightly smaller than the minimum diameter of the micropores in the backsheet using a punch press method, and then forming a burr protruding on the backside of the sheet. and (c) aligning the fine holes in both sheets and laminating and integrating both sheets by diffusion welding.

The present invention will be explained in detail below based on FIGS. 2 to 4.

The method for manufacturing an inkjet nozzle of the present invention includes:
As mentioned above, this method consists of the steps of obtaining an orifice back sheet, a step of obtaining an orifice sheet, and a step of laminating and integrating the above two sheets, and instead of forming the nozzle on a single plate as in the conventional method. This method attempts to form an inkjet nozzle having a desired shape by laminating two metal sheets together.

First, the process of obtaining an orifice back sheet will be explained based on _{FIG .} 30〜
This figure exemplifies the process of drilling a fine hole 2 of 60 μm and having a monoplane hyperboloidal expansion in the thickness direction, and in the figure, 3 is a die, 4 is a punch, and 5 is a holding plate.

In order to form microholes 2 in a sheet 1, first, as shown in FIG.
Note that the die 3 used here may have a simple opening like a normal die, but as shown in the drawing, it has a concave inner surface that is suitable for the expansion and deformation of the sheet 1 during plastic working. Place 6
Using the die 3 provided with this is effective in increasing the dimensional accuracy of the target microhole.

After the sheet 1 is fixed on the die 3, the punch 4 is driven through the opening 7 of the holding plate 5 to plastically work the sheet 1, as shown in FIG. The tip shape of the punch 4 used here needs to match the inner surface shape of the target microhole 2, and the depth of the recess 8 on the front side of the sheet 1 formed by this plastic working is It is necessary that the thickness be the same as or slightly deeper than the thickness _t1 of the sheet 1.

As a result of the plastic working, a convex portion 9 is formed on the back side of the sheet 1, as shown in FIG.
This sheet 1 is then ground using, for example, a conventionally known lapping machine to remove the convex portions 9, thereby forming the desired fine holes 2 with high dimensional accuracy.

In addition, in manufacturing the above-mentioned orifice back sheet, there is a method of drilling micro holes using a cutting tool,
Alternatively, a method using electroforming can be considered, but in the former case, it is extremely difficult to control the minimum diameter, and it is also difficult to process burrs/burrs, making it difficult to control the shape and dimensions of the tip of the micropore. On the other hand, in the latter case, radially extending stripes are likely to form on the inner peripheral surface of the micropores, and the material is nickel,
This is also not practical as it is limited to copper and the like. However, when using the method of the present invention described above, the process can be performed without any special skill by going through the two steps of plastic working with a punch press and grinding.
Micropores with high dimensional accuracy can be formed extremely easily.

Next, the process of obtaining an orifice sheet will be explained based on FIG. 3 _.
This example illustrates the process of forming micropores 12 having a constant diameter _d3 of 30 to 60 μm in a sheet 11 made of stainless steel with a diameter of 50 to 100 μm.

That is, in order to form micropores 12 having a constant diameter in the sheet 11, the sheet 11 is first placed on the die 13 as shown in FIG.
to fix the position. Next, when the punch 14 is inserted and pulled out as shown in FIG. By grinding the protruding burr 19 using a lapping machine or the like, a fine hole 12 having a constant diameter with high dimensional accuracy is formed as shown in FIG. At this time, due to the material of the sheet 11, the conditions of the punch press, etc., a slight sagging 20 occurs at the end peripheral edge of the fine hole 12, and its diameter _d4 is slightly larger than _d3 .
The existence of this sag 20 can be effectively utilized as will be described later.

Various methods can be considered for manufacturing the above-mentioned orifice plate, such as the drilling method, laser beam method, electric discharge machining method, electron beam method, and etching method. With other methods, it is difficult to form the inner surface of the micropores with a constant diameter and a smooth surface. but,
When using the method of the present invention described above, fine holes with high dimensional accuracy can be easily formed using the two steps of punching and grinding using the punch press method, without requiring special skill.

The orifice back sheet 1 and the orifice sheet 11 obtained as described above are assembled by a conventionally known diffusion welding method after aligning the respective fine holes 2 and 12, as shown in FIG. ,
The inkjet nozzle manufacturing method of the present invention is completed by laminating and integrating the inkjet nozzles.

With regard to the alignment of the micro holes 2 and 12 performed prior to this diffusion welding, it is important to note that the micro holes 2 and 12 are aligned in the orifice sheet 1 and the back sheet 11, respectively.
It is relatively easy to align the inkjet nozzles when they are provided one by one, but usually the head of an inkjet printer has a plurality of inkjet nozzles, and in this case, it is necessary to accurately align all the micropores. Although alignment is extremely difficult, a deviation of about ±2 μm does not disturb the laminar flow state of the ink jet so _much. Therefore, it is desirable to form the hole diameter _d3 of the fine holes 12 of the orifice sheet as small as 1 to 2 μm to facilitate the above-mentioned alignment. The presence of the sag 20 at the upper edge of the fine holes in the orifice sheet makes it possible to make the seam between the two fine holes 2 and 12 relatively smooth, so that a steady state of the ink jet can be easily achieved.

In manufacturing an inkjet nozzle according to the method of the present invention, when forming fine holes in the orifice back sheet and the orifice sheet by the punch press method, the inner peripheral surface of each fine hole is Punch friction marks may be formed, and such friction marks are extremely effective in maintaining laminar flow conditions of the ink jet formed through the nozzle.

As explained above, in the method of the present invention, a desired inkjet nozzle is formed by combining the micropores provided in each of two metal sheets, and the micropores are formed in each metal sheet individually. Since it is a combination of simple metal processing techniques that are known in the art and do not require much skill, the present invention allows inkjet nozzles that are close to the ideal shape to be manufactured with high dimensional accuracy and with good reproducibility. Since the length of the straight portion of the nozzle tip having a constant diameter that does not cause turbulence in the ink jet can be easily achieved by simply controlling the thickness of the metal sheet, its practical value is therefore very great.

[Brief explanation of drawings]

1A to 1D are cross-sectional views illustrating the shapes of ink jet nozzles formed by conventionally known methods, respectively. 2a-d are cross-sectional views showing the process of forming an orifice back sheet according to the present invention; FIGS. 3a-d are cross-sectional views showing the process of forming an orifice sheet; FIG. FIG. 3 is a sectional view showing the shape of an inkjet nozzle manufactured according to the method. 1,11...metal sheet, 2,12...microhole, 3,13...dice, 4,14...punch,
5, 15... Push plate, 6... Recess, 7, 17...
Opening, 8... recess, 9... protrusion, 19... burr,
20...Dare.

Claims (1)

[Claims] 1 a. Using a punch press method, a recess is formed in the metal sheet, the depth of which reaches at least the thickness of the sheet, and which extends upward from the bottom in the shape of a monoplane hyperboloid, and then protrudes from the back side of the sheet. A step of obtaining an orifice back sheet having micro holes by grinding away the convex portions, b. Forming micro holes with a constant diameter equal to or slightly smaller than the minimum diameter of the micro holes in the back sheet in the metal sheet by a punch press method. (c) Aligning the fine holes in both sheets and laminating and integrating the two sheets by diffusion welding. A method of manufacturing an inkjet nozzle, comprising: