JPH10339317A - Sheet carrying roller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce costs, surely grip a paper, and light a weight by forming fine projections like dots on an outer peripheral surface of a cylindrical base body made of metal material, and arranging a nickel phosphorus plating layer having the thickness within a specified value on at least surface of the projections. SOLUTION: A sheet carrying roller 1 is provided with a cylindrical base body 2 made of metal materials such as austenite stainless steel, aluminum alloy, and fine projections like dots are formed on an outer peripheral surface of the base body 2. The surface roughness of the outer peripheral surface of the base body 2 is preferably set to 5 μm and less, it is more preferably set to 3 μm and less. The fine projections 3 are arranged in a zigzag shape or in a checkered shape. Electroless nickel - phosphorus plating is carried out on the surface of the cylindrical base body 2 having the fine projections 3 so as to form a nickel - phosphorus layer having the thickness of 1 to 25 μm. And then, heat treatment is carried out thereon so as to provide the sheet carrying roller 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a roller for conveying a sheet material such as paper or plastic in an image forming apparatus.

[0002]

2. Description of the Related Art In image forming apparatuses such as various printers, electronic copiers, facsimile machines, and XY plotters, cassettes or the like are used to record various information including characters and figures on sheet materials such as paper and plastic. A transport device is provided which separates a large number of sheet materials accommodated in a stacked state one by one, feeds them into the apparatus main body, and transports the sheet materials to a recording area.

As a recording means system adopted for the image recording means of the image forming apparatus, there are an ink jet system, a wire dot system, a thermal system, a laser beam system and the like. An ink-jet type image forming apparatus will be described as an example of these recording methods with reference to FIG. The recording head 11 mounted on the carriage 10 performs printing on the sheet material S by discharging ink according to image information. Since the carriage 10 is connected to the lead screw 13, the carriage 10 reciprocates along the guide shaft 14 in a direction perpendicular to the paper by rotating the lead screw 13 by a drive source (not shown). Ink is ejected onto the sheet material S by driving the energy generating means (an electromechanical transducer such as a piezo element, a device which ejects droplets by heat generated by irradiation of an electromagnetic wave) of the recording head 11 with the movement of the carriage 10. Recording.

The means for conveying the sheet material S to the recording head 11 includes a sheet conveying roller 12 disposed on the back side of the sheet material S and a pinch roller 16 for pressing the roller. The sheet transport roller 12 is rotated by receiving power from a drive source (not shown) in order to apply a transport force to the sheet material S. Further, the pinch roller 16 is a driven roller made of metal, and both ends of the rotating shaft are urged by the leaf spring 15 and pressed against the sheet conveying roller 12.

In order to satisfy such demands, the conventional sheet conveying roller 12 is provided with a ring-shaped rubber member 12b made of natural rubber, chloroprene rubber, or the like, as shown in FIG. And a rubber roller whose surface is roughened by polishing is often used. However, although this rubber roller has the advantages of good frictional force (grip force) and wear resistance and low cost, the rubber is deformed with the lapse of time due to repeated use, and the dimensional accuracy (outer diameter dimensional tolerance, flexible ) Is reduced, so that accurate feeding accuracy cannot be obtained and the weight is large.

[0006]

Other sheet conveying rollers include a solid metal shaft having a surface sprayed with metal or a metal shaft having a surface coated with diamond abrasive grains by electrodeposition. Are used, each of which has excellent gripping force and wear resistance, but has the disadvantage that it is expensive, the accuracy is not so high, and the weight is large.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to eliminate the drawbacks of the prior art, and to provide a low-cost, high-dimensional accuracy, reliable gripping paper sheet, and a lightweight sheet conveying roller.

[0008]

In order to achieve the above-mentioned object, the present invention provides a cylindrical base made of a metal material, dot-like minute projections formed on the outer peripheral surface of the cylindrical base, and the projections. 1-2 formed at least on the surface of
And a nickel-phosphorus plating layer having a thickness of 5 μm. In the present invention, the outer peripheral surface of the cylindrical substrate has a surface roughness of 3 μm (R _z ) or less, and the nickel-phosphorus plating layer is H
It is desirable to have a hardness of v450 or more. Further, in the present invention, the height of the dot-like minute projections may be the same as the thickness of the nickel-phosphorus plating layer.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The details of the present invention will be described below with reference to the accompanying drawings. FIGS. 1A and 1B are perspective views showing a sheet conveying roller according to an embodiment of the present invention, and FIGS. 2A and 2B.
FIG. 3 is a plan view showing an arrangement of minute projections of the roller shown in FIG. 1, and FIG. As shown in FIG.
The sheet conveying roller 1 has a cylindrical base 2 made of a metal material such as austenitic stainless steel and an aluminum alloy, and dot-shaped minute projections 3 formed on the outer peripheral surface of the base. The base 2 may be in the form of a pipe {FIG.
It may be either reference {or solid {see FIG. 1 (b)}, but its outer peripheral surface needs to be smoothed, for example, by polishing. Specifically, the surface roughness of the outer peripheral surface (R _Z : ten-point average roughness according to JIS B 0601) is preferably 5 μm or less, more preferably 3 μm or less. Dot-shaped minute protrusion 3
Are arranged in a grid pattern (a) or a staggered pattern (b) as shown in FIG. The diameter (D) of the minute projections 3 (see FIG. 3) is preferably 0.2 to 0.8 mm, because if the diameter is small, the abrasion resistance is insufficient, and if the diameter is large, the grip becomes small. If the height (H) of the minute projections 3 is low, the gripping force is reduced, and if the height (H) is too large, the wear resistance is reduced. Therefore, the height (H) is preferably 0.05 to 0.2 mm. But the effect is enough. The arrangement interval (p) of the projections is 0.5 to 1 in terms of grip force.
mm is preferred. The microprojections 3 are formed by dot-printing a resist resin in the form of dots on the surface of the cylindrical substrate 2 and then immersing the substrate in an etching solution (hydrochloric acid, sulfuric acid, nitric acid, etc.) (or electrolytic etching may be used). You. In the case where the height (H) of the minute projections may be small, the etching step may be omitted, and only the thickness of the nickel-phosphorus plating may be applied. In this case, the roll material is SU
Steel such as M24 may be used, and rust prevention plating of the bearing shut portion may be shared. Here, screen printing can be performed by the apparatus shown in FIG. That is, the cylindrical substrate 2
Is in contact with the lower surface of the silk screen 20 having fine dot holes held by a support (not shown). Next, a doctor 21 is arranged on the upper surface of the silk screen 20, and a predetermined amount of a resist resin 22 is applied to a contact surface between the doctor 21 and the silk screen 20. Next, while rotating the cylindrical substrate 2 in a counterclockwise direction, the silk screen 20 is moved in the direction of the arrow (preferably, the peripheral speed of the substrate and the moving speed of the silk screen are equalized), so that the upper surface of the silk screen 20 is formed. The applied resist resin 22 is pressed by a doctor 21, passes through a dot hole (not shown) of the silk screen 20, and is applied to the outer peripheral surface of the cylindrical substrate 2 in a dot shape. The surface of the cylindrical substrate 2 having the fine projections 3 is made of electroless nickel
The nickel-phosphorous plating layer 4 is formed by performing phosphor plating (see FIG. 3), and then subjected to a heat treatment to obtain the sheet conveying roller of the present invention. This electroless nickel
Phosphorus plating is a method of chemically reducing metal ions with a reducing agent to deposit a plating film on a substrate. For example, acidic plating containing nickel sulfate, lactic acid, propionic acid, sodium hypophosphite, etc. (PH 4.5) ~ 5.5) by immersion along the plating (at a temperature of about 90 ° C). Generally, the nickel-phosphorus plating layer contains 2 to 15% of phosphorus in the precipitate. However, if the content of P is small, the wear resistance is reduced, and if the content of P is large, the coating becomes brittle.
Preferably, it has a composition of 8 to 10% by weight. The hardness as-plated is about Hv450-550,
Hardness of Hv700 or more can be obtained by heat treatment at 0 to 500 ° C.

[0010]

The following examples further illustrate the present invention. (Example 1) Outside diameter 19 mm, inside diameter 17.3 mm, length 4
After polishing the outer peripheral surface of a 72 mm SUS304 pipe to a surface roughness of 3 μm (R _z ) or less, the resist resin is formed in a dot shape over a 214 mm length on the surface of the pipe by the apparatus shown in FIG. And then immersed in an etching solution to obtain dot-like (cross-cut) microprojections (D = 0.2 mm, H =
0.1 mm, P = 1 mm). This pipe was placed in a plating bath (components: nickel sulfate 21 g / l, lactic acid 28 g /
l, 2.3 g / l propionic acid, 21 g / l sodium hypophosphite, PH: 5.0, temperature: 90 ° C), electroless nickel-phosphorus plating, and heat treatment (300 C. × 1 hr) to obtain FIG.
A sheet conveying roller (A roller) shown in FIG. The thickness of the plating layer of this roller was 15 μm, and its hardness (Hv) was 750. The weight of this roller is about 1
It weighed 80 g and was almost equivalent to the price of a rubber roller described later. (Example 2) A606 having an outer diameter of 19 mm and a length of 240 mm
After polishing the outer peripheral surface of a 4-roll (solid body having shaft portions at both ends) to a surface roughness of 3 μm (R _Z ) or less, the roll surface is formed in a dot-like (staggered) manner in the same process as above. Arrangement) Micro projections (D = 0.8mm, H = 0.1m)
m, P = 0.08 mm). This roll is subjected to electroless nickel-phosphorus plating under the same conditions as above,
Then, by performing a heat treatment (400 ° C. × 1 hr),
A sheet conveying roller (B roller) shown in FIG. 1B was prepared. The thickness of the plating layer of this roller was 20 μm, and its hardness (Hv) was 980. The weight of this roller was about 230 g, and was almost equal to the price of a rubber roller described later. (Comparative Example) On the other hand, for comparison, a SUM having a length of 472 mm was used.
A sheet transport roller (C roller) having an outer diameter of 19 mm as shown in FIG. 6 was prepared by fixing a ring made of chloroprene rubber to the solid shaft. The weight of this roller is about 650 g. Table 1 shows the measurement results of the grip force, wear resistance, outer diameter dimensional accuracy, and deflection accuracy of each roller.

[0011]

[Table 1]

From Table 1, it can be seen that both the A roller and the B roller have high gripping force and abrasion resistance, and also have high accuracy. On the other hand, it can be seen that the rubber roller C has a good grip force, but has low dimensional accuracy and low deflection accuracy. The grip force is sandwiched between a φ20 (mm) driven (pinch roller) rubber roller that presses a predetermined A4 sheet at about 600 g, and a tension gauge that draws the A4 sheet when the conveyance roller is rotated. Was measured. The abrasion resistance was evaluated by measuring the grip force every 2,000 sheets by passing only the paper at a high speed using the same acceleration tester as the grip force measurement, and taking the number of sheets whose grip force was reduced by 20% as the abrasion resistance.

[0013]

As described above, according to the present invention, a rough surface having a specific surface roughness is formed on the outer peripheral surface of a metal shaft, so that it is lightweight, highly accurate, and has a large grip force. A low-cost sheet conveying roller can be obtained.

[Brief description of the drawings]

FIG. 1 is a perspective view illustrating a sheet conveying roller according to an embodiment of the present invention.

FIG. 2 is a plan view showing an arrangement of minute projections of the roller shown in FIG.

FIG. 3 is an enlarged sectional view of a portion A in FIG.

FIG. 4 is a sectional view of an apparatus for manufacturing the roller shown in FIG.

FIG. 5 is a schematic sectional view of a main part of the injection image forming apparatus.

FIG. 6 is a perspective view showing a conventional sheet conveying roller.

[Explanation of symbols]

 1 Sheet transport roller, 2 pipe, 3 micro projection

Claims (3)

[Claims] 1. A cylindrical base made of a metal material, a dot-shaped micro-projection formed on the outer peripheral surface of the cylindrical base, and a nickel having a thickness of 1 to 25 μm formed on at least the surface of the projection. A sheet conveying roller having a phosphor plating layer. 2. The outer peripheral surface of the cylindrical substrate has a surface roughness of 3 μm (R _Z ) or less, and the nickel-phosphorus plating layer has an Hv4
The sheet conveying roller according to claim 1, wherein the roller has a hardness of 50 or more. 3. The height of the dot-like minute projections is nickel-
2. The sheet conveying roller according to claim 1, wherein the thickness of the sheet is a phosphorus plating layer.