JPH0990811A - Fixing roller and manufacture thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fixing roller high in safety, low in cost and simple in constitution by forming a drawing part after a heat pipe is embedded in a cylindrical core bar drawing work is applied to both end parts of the core bar and hermetically sealing the heat pipe in the core bar. SOLUTION: The heat pipe 2 is inserted in the core bar 1 provided with a hole for a heat pipe 1a by an extrusion molding method. Thereafter, the drawing work is applied to both ends of the bar 1 so as to form the drawing part (journal part) 1b. At this time, the aperture part of the hole 1a of the bar 1 used when the pipe 2 is inserted is perfectly closed and the pipe 2 is hermetically sealed. When the drawing part 1b is formed by conducting a drawing work, the end part of the pipe 2 is crushed and the other part expands, so that a gap between the pipe 2 and the hole 1a is eliminated. Thus, the explosion accident of the heat pipe that the pipe 2 blown up because the fixing roller abnormally generates heat and the adverse effect thereof is exerted on the outside is prevented from occurring.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is used in an electrophotographic image forming apparatus such as a copying machine or a printer, and a fixing roller in a heat roller fixing device for fixing an unfixed toner image using a heat roller pair, and The present invention relates to a manufacturing method thereof.

[0002]

2. Description of the Related Art Conventionally, a heat roller fixing device is composed of a fixing roller and a pressure roller provided so as to face the fixing roller so as to be in pressure contact with the fixing roller. In this fixing roller, a halogen heater or the like is incorporated in a hollow cylindrical core metal, and on the surface of the core metal, for example, fluororesin such as PFA or PTFE, silicone rubber, fluororubber, a mixture of fluororubber and fluororesin, or a mixture thereof. On the other hand, the pressure roller (not shown) is provided with an elastic layer of silicone rubber, fluororubber, a mixture of fluororubber and fluororesin, etc. on the core metal. Further, a non-adhesive layer such as a PFA tube is provided if necessary. By the way, in the heat roller fixing device, it is desired to raise the temperature in a short time after the power is turned on, and this is required particularly in a low speed type device. As a countermeasure for this, the core metal can be thinned to reduce the heat capacity, but since the heat generation distribution of the heater appears on the surface as it is, another problem that it is difficult to make the temperature distribution uniform occurs.

Further, when images are continuously formed, heat is taken by the transfer paper and the surface temperature of the fixing roller is lowered. If the amount of heat generated by the heater is controlled by detecting the decrease in the surface temperature at this time, the temperature rises too much when the transfer paper is not passing, causing hot offset of the toner, wrinkles of the transfer paper, and even the release layer. Problems such as peeling occur. As a countermeasure, there is a method in which a plurality of heaters having different light emission distributions are built in the fixing roller, and a plurality of temperature detecting means are provided at different positions in the fixing roller longitudinal direction to control the temperature. There are problems such as an increase in the number of points, complication of control, an increase in cost and a decrease in reliability due to an increase in the number of parts.

Therefore, in JP-A-4-139481 and JP-A-4-360185, a heat pipe is incorporated in the fixing roller to make the temperature distribution uniform. In the former Japanese Patent Application Laid-Open No. 4-139481, in a fixing roller in which a plurality of heat pipes are embedded in a thick wall of a hollow cylindrical core metal having a heater inside, the fixing roller is improved by improving the internal structure of the heat pipe. By improving the temperature distribution and further providing the temperature detecting means in the non-sheet passing portion of the fixing roller, the release layer on the surface of the fixing roller is less likely to be scratched or worn. JP-A-4-3601 of the latter
In Japanese Patent Laid-Open No. 85, the heater power is also reduced by making the heat pipe parallel to the axis of the fixing roller and making the length of the heat pipe and the heat generating portion of the heater shorter than the paper passing area. . There are various advantages in using the fixing roller using the heat pipe in the heat roller fixing device.

[0005]

However, as shown in FIG. 4, there is a conventional fixing roller of the type in which the heat pipe insertion opening 1a is opened at the end of the core metal 1, as shown in FIG. When the temperature rises abnormally due to thermal runaway,
It was necessary to braze the heat pipe insertion opening 1a in order to prevent damage to the outside due to the rupture of the heat pipe 2. Also, as shown in FIG. 5, there is also a type in which a heat pipe 2 is built in a cored bar pipe 5 and journal portions 3 having a reduced diameter are provided at both ends thereof for mounting bearings and gears. Since the thick cored bar 5 including the scraped amount of the journal part 3 is used or the journal part 3 is joined to the thin body part by welding, pressure welding, press fitting, etc. Therefore, there are problems that the cost becomes high and that the number of steps such as centering for positioning at the time of joining is required.

Further, in order to fix the heat pipe in the fixing roller, it is necessary to heat the pipe after inserting the heat pipe to expand the heat pipe to plastically deform it or to enclose high clay grease. Since the temperature is raised to the vicinity where the heat pipe bursts, there are problems that stress remains in the weak part of the heat pipe, shortening the life, and reducing the thermal conductivity due to the presence of grease. Therefore, the present invention solves the above-mentioned conventional problems, and has a journal portion whose both ends are thinned by a thin cored bar containing a heat pipe, good heat conduction performance, no thermal stress remains, An object of the present invention is to provide a fixing roller having a high safety, a low cost and a simple structure, and a manufacturing method thereof.

[0007]

According to the first aspect of the present invention,
In a fixing roller having a hollow cylindrical cored bar for disposing a heater, a heat pipe embedded in a thick wall of the cylindrical cored bar, and both ends of the cylindrical cored bar. And a drawing process for sealing the heat pipe formed in the above in a core metal. According to a second aspect of the present invention, in a fixing roller in which a plurality of heat pipes are embedded in a thick wall of a cylindrical cored bar having a hollow interior for disposing a heater, the cylindrical cored bar is provided. After the heat pipe is embedded in the core metal, both ends of the cored bar are drawn to form drawn parts, and the heat pipe is sealed in the cored bar. According to the invention of claim 3, the length of the heat pipe is equal to or more than the length of the cylindrical cored bar excluding the throttled portion, and the end of the heat pipe is squeezed together with the cored bar to form the throttled portion. It is in the method of manufacturing the roller.
According to a fourth aspect of the present invention, in the fixing roller, the diameter of the hole for burying the heat pipe is larger than the diameter of the heat pipe, and the inner diameter D1 of the portion of the cylindrical core metal for burying the heat pipe is It is formed so as to be smaller than the inner diameter D2 of the portion other than the above, and is formed so as to project into the hollow portion. After burying the heat pipe, a cylindrical mold having a diameter D satisfying D1 <D ≦ D2 is inserted into the hollow portion and squeezed. The method for manufacturing a fixing roller comprises fixing the heat pipe by deforming the portion where the heat pipe is embedded.

[0008]

Embodiments of the present invention will be described below with reference to the drawings. In FIG. 1, a heat pipe 2 is inserted into a core metal 1 having a heat pipe hole 1a formed by extrusion molding, and thereafter, both ends are subjected to a drawing process to obtain a drawn part (journal part).
1b is formed. At that time, the opening of the hole 1a of the core metal 1 when the heat pipe 2 is inserted is completely crushed, and the heat pipe 2 is in a sealed state. A method of manufacturing the fixing roller according to claim 2 will be described. The length L1 of the heat pipe 2 before drawing the fixing roller shown in FIG. 2A is the length of the portion of the core metal 1 shown in FIG. It is larger than L2.

As a result, as shown in FIG. 2B, when the drawing process is performed to form the drawn portion 1b, the end portion of the heat pipe 2 is crushed, and the other portions of the heat pipe 2 are expanded and heat is applied. The gap between the pipe 2 and the heat pipe hole 1a can be eliminated.

An embodiment based on claim 3 will be described. As shown in FIG. 3 (a), the cored bar 10 is formed thin so as to reduce the temperature rise time, but the portion where the heat pipe hole 10a is located protrudes into the hollow portion. To form a convex portion 10b, and the hole 10a
Is slightly larger than the outer diameter of the heat pipe 2. At the time of manufacturing, the heat pipe 2 is inserted into the heat pipe hole 10a. Then, the convex portion 10 of the core metal 10
Assuming that the inner diameter of b is D1 and the inner diameters of other portions are D2, as shown in FIG. 3B, the inner diameter is larger than the inner diameter D1,
A cylindrical mold 6 (shown by a broken line) having an inner diameter D smaller than D2 is inserted into the hollow portion of the cored bar 10 and a squeezing step is performed. Thereby, the hole 10a for the heat pipe
The heat pipe 2 is crushed by the cylindrical mold 6 to eliminate the void. The outer diameter D of the cylindrical mold 6 at this time is D1
In the range of <D ≦ D2, it is determined by the ratio of voids.

[0011]

As described above, according to the first aspect of the present invention, after the heat pipe is embedded in the cylindrical cored bar, both ends of the cored bar are drawn to form the drawn part. And because the heat pipe is sealed in the core metal, the processing process can be simplified, and the heat pipe explosion accident that the heat pipe ruptures due to abnormal heat generation of the fixing roller and external damage is also prevented. It is possible to obtain a low-cost and safe fixing roller. Further, since the core metal is integrally processed, reliability is improved without any accident such as disengagement due to defective joint of the conventional journal portion.
Further, even when the grease is sealed so that the air layer is not left in the core metal, the leakage can be completely prevented. Claim 2
According to the invention described, the length of the heat pipe is equal to or greater than the length of the cylindrical cored bar excluding the throttled portion, and the end portion of the heat pipe is squeezed together with the cored bar to form the throttled portion. In addition to the same effect as the first aspect, it is possible to completely eliminate the voids generated in the vicinity of the end portion of the heat pipe and improve the thermal efficiency. According to the invention of claim 3, the diameter of the hole for burying the heat pipe is made larger than the diameter of the heat pipe, and the inner diameter (D1) of the portion of the cylindrical core metal for burying the heat pipe is other than that. Inner diameter of part (D
It is formed so as to project into the hollow portion so as to be smaller than 2), and after burying the heat pipe, D1 <
Since a mold having a diameter D of D ≦ D2 is inserted and ironed, and the heat pipe is fixed by deforming the portion in which the heat pipe is embedded, the heat pipe life due to heat stress is obtained in addition to the same effect as in claim 2. It is possible to avoid the deterioration of grease and leakage of grease.

[Brief description of drawings]

FIG. 1 is a sectional view of a fixing roller showing an embodiment of the present invention.

FIG. 2 is a cross-sectional configuration diagram showing a method of manufacturing a fixing roller according to claim 2.

FIG. 3 is a cross-sectional configuration diagram illustrating a method of manufacturing a fixing roller according to claim 3.

FIG. 4 is a cross-sectional configuration diagram showing a conventional fixing roller.

FIG. 5 is a cross-sectional configuration diagram showing a conventional fixing roller having a journal portion.

[Explanation of symbols]

 1 Cylindrical core metal 1b Drawing part (journal part) 2 Heat pipe 6 Cylindrical mold

Claims (4)

[Claims] 1. A fixing roller having a hollow cylindrical cored bar for arranging a heater, comprising: a heat pipe embedded in a thick wall of the cylindrical cored bar; And a drawing process for sealing the heat pipes formed on both ends of the cored bar in the cored bar. 2. A fixing roller in which a plurality of heat pipes are embedded in a thick wall of a cylindrical cored bar having a hollow interior for arranging a heater, wherein After burying the heat pipe, both ends of the core metal are drawn to form drawn parts,
A fixing roller comprising a heat pipe sealed in a core metal, and a method for manufacturing the fixing roller. 3. The length of the heat pipe is equal to or greater than the length of the cylindrical cored bar excluding the narrowed part, and the end part of the heat pipe is squeezed together with the cored bar to form the narrowed part. The fixing roller according to claim 1, and a method for manufacturing the fixing roller. 4. In the fixing roller, the diameter of the hole for burying the heat pipe is made larger than the diameter of the heat pipe, and the inner diameter D1 of the portion of the cylindrical core metal for burying the heat pipe is other than that. Inner diameter of part D2
It is formed so as to project into the hollow portion so as to be smaller than that, and after the heat pipe is buried, D1 <
Insert and squeeze a cylindrical mold with a diameter D such that D ≦ D2,
A fixing roller and a method of manufacturing the fixing roller, characterized in that the heat pipe is fixed by deforming a portion where the heat pipe is embedded.