JPH08146802A - Method for forming crown-shaped or inverted crown-shaped structure and fixing roller manufactured by this method - Google Patents

Abstract

(57) [Abstract] [Purpose] It is suitable for energy saving because it eliminates significant deformation due to internal stress that occurs when forming a structure in which a cylindrical core body is coated with organic matter into a crown shape or an inverted crown shape. A thin type fixing roller is provided. [Structure] A cylindrical body 1 in which a core is coated with an organic substance is heated to melt the organic substance to form a film, and then the core is cooled with a temperature distribution in the axial direction.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a crown-shaped or inverted-crown-shaped structure in which a cylindrical core is coated with an organic material, and more particularly to a fixing roller used in an image forming apparatus such as a copying machine, a facsimile, a printer or the like. The present invention relates to a forming method and a fixing roller of an image forming apparatus formed by this method.

[0002]

2. Description of the Related Art A fixing roller used in a fixing device of an image forming apparatus has an axial center outer diameter outside both ends in order to prevent jamming of copy paper and wrinkling of thick objects such as envelopes. It is processed and formed into an inverted crown shape (stepping type) slightly smaller than the diameter.

Generally, the fixing roller is formed by coating a cylindrical cored bar of a heat conductor such as metal with a fluororesin having a good releasability. In most cases, an aluminum core bar, which is a lightweight and good conductor of heat, is used as the core bar. The fluororesin film has a thickness of about 20 μm in order to ensure smooth flatness.

Conventionally, the above-mentioned processing of the above-mentioned inverted crown shape of the fixing roller is a method of increasing the cutting allowance at the axial center part of the core bar at the time of cutting machining, or the both end parts of the core bar. A method of inserting a frustoconical jig into the inside and performing swaging is adopted.

In recent years, as one of the energy-saving measures, there is a measure to make the fixing roller core metal thin to improve the heat transfer and to reduce the waiting time from the time when the image forming apparatus is turned on until the actual image formation. Has been adopted. However, if the core metal is made thinner as described above, chattering will occur during machining and it will be difficult to obtain sufficient machining accuracy.In addition, after swaging, the coating will be applied and the fusion coating will be formed by heating. Then, it was unavoidable that the internal stress generated at the time of processing caused remarkable deformation.

[0006]

SUMMARY OF THE INVENTION The object of the present invention is to solve the above-mentioned problems that occur during the production of a crown-shaped or inverted crown-shaped cylindrical structure coated with an organic material, especially a fixing roller, and is suitable for energy saving. Another object of the present invention is to provide a method for forming a thin-walled structure, and a fixing roller formed by this method.

[0007]

In order to form the above-mentioned surface coating, the following method is generally used.

(I) Powder electrostatic coating (ii) Wet spray coating (iii) Fiber winding (iv) Heat shrinkable tube extrapolation In either of these methods, heat treatment such as firing is subsequently performed, and particularly, In the methods (i) to (iii), a temperature above the melting point of the resin is applied.

[0009] As is generally the case with thermoplastic resins, particularly fluorine-based resins have significant stress that shrinks when they are cooled after melting, and when melted and cooled on a flat plate, they deform so that they warp convexly to the metal surface side. .

On the other hand, when the fluorine resin is uniformly applied to the cylindrical aluminum and baked, the straightness and the roundness do not cause any problems in actual use. This is because the stress during cooling shrinkage is uniformly applied in the radial direction. On the contrary, when the stress is unevenly applied,
It means that some deformation occurs.

The present invention is based on the above-mentioned recognition, and positively utilizes the above-mentioned phenomenon at the time of cooling shrinkage of a resin to form a crown-shaped structure or an inverted crown-shaped structure. Is to eliminate.

Therefore, according to the present invention, the above object is to coat the core of the cylindrical structure with an organic substance, heat the organic substance to melt the organic substance to form a coating, and to form a temperature distribution in the axial direction of the core. It is solved by a forming method of holding and cooling.

Further, according to the present invention, the above object is to coat a core with an organic substance, heat the core to melt the organic substance to form a film, cool this, and then distribute the temperature in the axial direction of the core. It is solved by a forming method of heating and cooling by holding.

Further, according to the present invention, a thin aluminum cylinder is coated with a fluororesin, which is heated to melt the fluororesin to form a film, and then a temperature distribution is provided in the axial direction of the aluminum cylinder. The above problems are solved by a fixing roller which is cooled and formed into an inverted crown shape.

Further, in the formation of the above-mentioned fixing roller, the film is melted to form a film and then cooled, and then the aluminum cylinder is provided with a temperature distribution in the axial direction and heated and cooled to form an inverted crown shape. The above-mentioned problems can be solved by the roller.

[0016]

According to the invention of claim 1, a cylindrical core body, for example, an aluminum cylinder is coated with an organic substance such as a fluororesin, and this is heated to melt the organic substance to form a film. Cool with a temperature distribution in the direction. In this case, since the core is formed by grinding a straight tube,
Even if it is thin, processing is easy. Further, since the coating of the organic substance is a coating on a straight tube, any of powder coating, wet spraying, fiber winding, and heat shrinkable tube can be used, and the coating can be easily formed.

Further, since the crown shape or the inverted crown shape is generated only by controlling the temperature distribution, the formation of the core body and the coating film described above are facilitated.

A suitable fixing roller is formed by using an aluminum cylinder as the core and using a fluororesin such as PFA or PTFE as the coating layer. For example, PFA as a fluororesin has a melting point of around 310 ° C. and is usually baked at 380 ° C., but PFA is 310 ° C.
When the temperature becomes below, it solidifies, and there is a temperature change point at 170 to 180 ° C., and the stress becomes maximum during that time.

On the other hand, aluminum has a melting point of 6
It is 50 ° C., and is annealed and softened by heat treatment at 200 ° C. or higher, but is stable at 200 ° C. or lower. Therefore, the coating structure once formed can be stably used in the range of normal temperature to 180 ° C., which is the range of use of the fixing roller.

According to the second aspect of the present invention, since the material is once fired and cooled, and then reheated and cooled, the processing is easy even if the surface polishing step is performed therebetween.

In both of the above inventions, an aluminum cylinder is used as the core body, and a fluorine resin such as PFA or PTFE is used as the coating layer, whereby a suitable fixing roller having an inverted crown shape of a thin cored bar can be obtained. . The copy paper made with this fixing roller is prevented from wrinkling,
A good quality copy image is achieved.

[0022]

Embodiments of the present invention will be described below with reference to the drawings.

A cylindrical body 1 shown in FIG. 1 comprises an aluminum core metal 2 and a fluororesin coating layer 3 coated on the outer periphery thereof. FIG. 2 shows the cylindrical body before being formed into an inverted crown shape, and has the same outer diameter D ₁ in the axial direction. FIG.
Shows a cylindrical body 1 ′ after being processed and formed into an inverted crown shape, which has an outer diameter D ₂ at the center in the axial direction with respect to an outer diameter D _{1 at} both ends. In this case, D ₁ > D ₂ .

Next, an example of processing and forming the fixing roller according to the present invention will be described.

Example 1: Wall thickness 0.4 mm, outer diameter 20 mm
Grinding φ aluminum cylinder, surface roughness Rz = 6.0
After finishing to less than μm, fluororesin PFA (MP612 made by Mitsui DuPont Fluorochemicals) was electrostatically coated. Then, in a cylindrical coaxial furnace 4 shown in FIG.
Bake for minutes. The film thickness of the fluororesin after firing is 20 μm. In the cylindrical coaxial furnace 4, a heater H ₁ is provided at the center in the axial direction.
And the heater H ₂ , the heater H ₃ , and the heater H ₄ are sequentially arranged at both ends around the heater H ₁ as shown.

After the firing, the heaters H ₃ and H ₄ were cut off, and the input was controlled so that the heater H ₁ was cooled at 10 ° C./min and the heater H ₂ was cooled at 20 ° C./min. . This control is performed until the actual temperature of the structure becomes 200 ° C. or lower, and the sample No. Got 1.

Example 2: Thickness 0.4 mm, outer diameter 20 mm
Carbon-dispersed PFA in a φ grinding aluminum cylinder
The fiber (1200d / 6f) was wound, heated and melted in a firing furnace, allowed to cool and cooled as it was, and the surface was tape-polished to be smooth to obtain a 20 μm coating film. While the cylinder was held by a chuck and rotated, only the vicinity of the central portion was heated by a high frequency induction heating device 5 (200 Hz: manufactured by High Frequency Nestle) shown in FIG. Switch to cooling at the ultimate temperature of 340 ° C,
The sample No. was cooled at 10 ° C. per minute. 2 was obtained.

Example 3: Wall thickness 0.4 mm, outer diameter 20 mm
A φ-ground aluminum cylinder was spray-coated with a PTFE resin (DuPont, 857-305), uniformly heated to 380 ° C. for 30 minutes, and then cooled. Then, as shown in FIG. 6, the halogen lamp heater 6 coaxially adjusted to the center of the aluminum cylinder is used to heat the aluminum cylinder to 320 ° C.
The temperature was raised to. Then, the sample No. was cooled at 20 ° C. per minute. 3 was created.

By carrying out a comparative example to each of the above-mentioned examples,
The following results were obtained.

Comparative Example 1: An aluminum cylinder, its surface layer coating, and heating and firing were performed in the same manner as in Example 1, and then uniformly cooled in the axial direction. Got 4.

Comparative Example 2: Wall thickness 0.4 mm, outer diameter 20 mm
The surface of the φ aluminum cylinder was ground so that the center portion was reduced by 30 μm. In this case, a lot of chattering occurred. In addition to this, as in the third embodiment,
Fluorine resin is spray-applied and uniformly heated and cooled.
Sample No. Got 5.

Comparative Example 3: Using the same aluminum cylinder as in Example 3, jigs each having a taper inside were inserted from the respective ends, and swaged to form an inverted crown shape. Thereafter, in the same manner as in Example 3, the fluororesin is spray-coated, and then uniformly heated and cooled, and then the sample No. Got 6.

As described above, the sample Nos. Obtained in Examples 1 to 3 and Comparative Examples 1 to 3 were used. The outer diameter D ₁ of both ends of each roller 1 to 6 and the outer diameter D _{2 of the} central portion in the axial direction were measured, and then each roller was mounted on a Ricoh facsimile C31 and copied to confirm the image quality. The results are shown in the table below. In this table, the degree of crown d (mm) = (D ₁ −D ₂ ) / 2.

[0034]

【table】

As shown in the above table, all of Examples 1 to 3 according to the method of the present invention were free from paper wrinkles and good image quality was obtained, whereas Comparative Examples not according to the method of the present invention were obtained. In Nos. 1 to 3, paper wrinkles or image quality problems occurred.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view of a structure before applying the method of the present invention.

2 is a perspective view of the structure of FIG. 1. FIG.

FIG. 3 is a perspective view exaggerating the outer diameter difference of the structure after applying the method of the present invention.

FIG. 4 is a vertical cross-sectional view of a cylindrical coaxial heating furnace in which a structure is placed inside and local heat distribution is possible.

FIG. 5 is a vertical cross-sectional view of a high frequency induction heating device having a structure inside.

FIG. 6 is a vertical cross-sectional view of a structure in which a heating element is arranged inside.

[Explanation of symbols]

1 Structure before processing according to the present invention 1'Structure after processing according to the present invention 2 Aluminum core metal 3 Cloth layer 4 Cylindrical coaxial heating furnace 5 High frequency induction heating device 6 Halogen lamp heater D ₁ Outer diameter of both ends of structure Outside diameter of axial center of D ₂ structure H ₁ ~ H ₄ heater

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI technical display location C09D 127/12 PFG

Claims (4)

[Claims] 1. A method for forming a crown-shaped or inverted crown-shaped structure in which a cylindrical core body is coated with an organic substance, the cylindrical core body is coated with the organic substance, and the organic substance is melted by heating. Forming a coating film, and then cooling the core body with a temperature distribution in the axial direction. 2. A method for forming a crown-shaped or inverted crown-shaped structure in which a cylindrical core body is coated with an organic substance, wherein the cylindrical core body is coated with the organic substance and the organic substance is melted by heating. To form a coating, cool the coating, and then heat and cool the core with a temperature distribution in the axial direction. 3. A thin-walled aluminum cylinder is coated with a fluororesin, and this is heated to melt the fluororesin to form a film, and then the aluminum cylinder is cooled with a temperature distribution in the axial direction. , A fixing roller formed in an inverted crown shape. 4. A thin-walled aluminum cylinder is coated with a fluororesin, which is heated to melt the fluororesin to form a film, which is cooled and then has a temperature distribution in the axial direction of the aluminum cylinder. The fixing roller is characterized in that it is heated and cooled to form an inverted crown shape.