JP3023308B2 - Fixing roll for electrophotographic equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a fixing roll for an electrophotographic apparatus, and more particularly, to a fixing roll for an electrophotographic apparatus in which a heat pipe is embedded in a cored bar.

[0002]

2. Description of the Related Art Conventionally, in a so-called electrophotographic apparatus for forming an image on a sheet by using toner or the like, a heat roll fixing system is generally adopted. The fixing roll used in this method is provided with a halogen heater and the like in a hollow core, and a release layer made of a fluororesin or the like on the outer surface of the core, and heat-presses toner and the like on paper. It is established. In addition, when a large amount of copying is performed at a high speed, heat is deprived of the paper, and the surface temperature of the fixing roll partially decreases. Therefore, it has been considered to embed a so-called heat pipe in which a heat medium liquid (for example, water) is sealed in a metal core of a fixing roll in parallel with its axis. With this heat pipe, the surface temperature of the fixing roll can be made uniform.

[0003] The closer the heat pipe is to the core metal, the better the surface temperature of the fixing roll can be made uniform. Therefore, conventionally, a method of fixing a heat pipe to a hole formed in a metal core by shrink fitting or the like has been adopted.

[0004]

However, if the heat pipe is fixed to the fixing roll by shrink fitting or the like, the heat pipe cannot be removed from the cored bar. On the other hand, since the release layer provided on the outer surface of the core metal gradually peels off,
The cored bar has a certain life (for example, in some copiers,
About 300,000 A4 sheets). For this reason, the heat pipe must be discarded together with the core metal, even though it is still usable.

It is also conceivable to form a release layer again on the outer surface of the core metal and reuse it. However, in order to form a release layer of a fluororesin or the like, it is necessary to heat to a high temperature of about 400 ° C. . When the heat pipe is heated to such a high temperature together with the metal core, the vapor pressure of the heat medium liquid becomes extremely high, and the heat pipe is broken. As described above, in a fixing roll using a heat pipe, there is no waste in replacing parts, and the maintenance cost of an electrophotographic apparatus using the fixing roll cannot be sufficiently reduced.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a fixing roll for an electrophotographic apparatus capable of favorably reducing the maintenance cost of the electrophotographic apparatus.

[0007]

Means for Solving the Problems and Effects of the Invention The invention according to claim 1, which has been made to achieve the above object, comprises: a hollow cylindrical core metal having a release layer made of a fluororesin on its outer surface; A heat pipe embedded in the core metal in parallel with the axis of the core metal, and a fixing roll for an electrophotographic apparatus , comprising:
It is embedded and fixed in the core metal by the used soldering.
It is characterized in that it can be extracted from the core metal at the time of melting . Fixing roll operating temperature <solder melting point
<Temperature at which the above heat pipe undergoes plastic deformation

[0008] In the present invention thus configured, the heat pipe is removably embedded in the cored bar. For this reason,
When the core has reached the end of its life, even though the heat pipe is still usable, the heat pipe can be withdrawn from the core and only the core replaced. Further, it becomes possible to form a release layer again on the outer surface of the cored bar after removing the heat pipe and reuse it. Therefore, in the fixing roll for an electrophotographic apparatus according to the present invention, it is possible to eliminate waste of component replacement and satisfactorily reduce the maintenance cost of an electrophotographic apparatus using the fixing roll.

Further, in the present invention, since the heat pipe is embedded and fixed to the metal core by soldering, the heat pipe can be easily brought into close contact with the metal core via solder. In addition, solder has extremely excellent thermal conductivity.
For this reason, the surface temperature of the fixing roll can be made extremely excellent and uniform. Also, since the heat pipe can be extracted from the core by melting the solder,
The attachment and detachment of the heat pipe is very easy.

Accordingly, in the present invention, as well as even better homogenize the front surface temperature, it is possible to further facilitate heat pipe detachably. The melting point of the solder is
Since the temperature is higher than the operating temperature, solder
Can be prevented from melting. In addition, the melting point of solder
Is lower than the temperature at which the top pipe is plastically deformed.
The plastic deformation of the heat pipe during melting can also be prevented . According to a second aspect of the present invention, in addition to the configuration of the first aspect of the present invention, the heat pipe is formed of a copper tube tempered to ＨH or more, and the solder has a melting point of 240 to 300 ° C. It is characterized by:

In general, an electrophotographic apparatus is often used by heating a fixing roll to 180 to 200 ° C. Therefore, in consideration of the overshoot of the fixing roll temperature and the tolerance of the temperature sensor, it is desirable to set the melting point of the solder to 240 ° C. or higher in order to prevent the melting of the solder during use of the electrophotographic apparatus. Further, in order to suppress the thermal deformation of the heat pipe even when heated to 240 ° C. or more, and to prevent the attachment and detachment of the heat pipe and the flow of the solder from being hindered, the heat pipe is tempered to 1 / 2H or more. It is desirable to be constituted by a copper tube made. Furthermore, to prevent the heat pipe from being plastically deformed by heating,
The melting point of the solder is 300 ° C or less (more preferably, 270 ° C
The following is desirable.

In the present invention, the material of the heat pipe and the melting point of the solder are set as described above. For this reason, in addition to the effect of the invention described in claim 1 , the heat pipe can be prevented from being deformed when the heat pipe is attached and detached, and the heat pipe can be reused more favorably. There is an effect that the solder can be prevented from being melted during use.

[0013]

Next, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a cross-sectional view illustrating a configuration of a fixing roll (hereinafter, simply referred to as a fixing roll) 1 for an electrophotographic apparatus to which the present invention is applied. As shown in FIG. 1, a fixing roll 1 is provided inside a thick inner wall of a hollow cylindrical cored bar 3 made of a JIS No. 6000-series or 3000-series aluminum alloy and is parallel to the axis XY of the cored bar 3. Multiple cylindrical holes 5
And a heat pipe 7 is embedded in the cylindrical hole 5. Further, a release layer made of a fluororesin is provided on the outer surface of the cored bar 3. In addition, AA of FIG.
As shown in the sectional view of the line, the cylindrical hole 5 has 12 holes around the axis XY.
Three heat pipes 7 (omitted in FIG. 2) are buried in the respective cylindrical holes 5.

FIG. 3 is a partial sectional view showing the structure of the heat pipe 7. As shown in FIG. As shown in FIG. 3, the heat pipe 7
A tube 11 made of a phosphoric acid-deoxidized copper tube C1220T (refer to JIS H3300: oxygen-free copper tube C1020T may be used) and having a thickness of 0.5 mm made of 1 / 2H heat-treated material (or H-heat-treated material). A spiral groove 13 is formed on the inner surface of the tube 11. In the tube 11, a wick 15 formed by bending a phosphor bronze wire into a hairpin shape and twisting it (for example, Japanese Unexamined Patent Publication No.
No. 481), and water as a heat transfer fluid is sealed. The wick is not limited to this example, and a conventionally well-known wick such as a wire mesh wick can also be used. Further, the tube may be a smooth tube.

After the heat pipe 7 is inserted into the cylindrical hole 5 as shown in the sectional view of FIG.
The space between the inner wall 5a and the tube 11 is filled with solder 17 and fixed. The solder 17 is filled by inserting the heat pipe 7 into the cylindrical hole 5 with the fixing roll 1 standing upright and closing the lower end of the cylindrical hole 5, and then filling the gap between the cylindrical hole 5 of the fixing roll 1 and the heat pipe 7. The injection can be performed by injecting the molten solder. Alternatively, the injection can be performed by inserting the heat pipe 7 into the cylindrical hole 5 after injecting the molten solder into the cylindrical hole 5. In any case, by cooling the molten solder, the heat pipe 7 is fixed integrally with the fixing roll 1 via the layer of the solder 17. The solder 17 has a melting point of 240 to 300 ° C, more preferably 240 to 270 ° C.

In the fixing roll 1 configured as described above,
The heat pipe 7 can be easily extracted from the cylindrical hole 5 by melting the solder 17. For this reason,
The following effects are obtained. The release layer formed on the outer surface of the metal core 3 gradually peels off during use of the electrophotographic apparatus, and
Has a predetermined life, but the heat pipe 7 may still be sufficiently usable even when the core metal 3 reaches the life. Therefore, in such a case, the heat pipe 7 can be removed from the core 3 and only the core 3 can be replaced. Further, it becomes possible to form a peeling layer again on the outer surface of the cored bar 3 after extracting the heat pipe 7 and reuse it. Therefore, in the fixing roll 1, the maintenance cost of the electrophotographic apparatus using the fixing roll 1 can be satisfactorily reduced by eliminating waste of component replacement. In addition, how to remove the heat pipe 7 is as follows.
If the fixing roll 1 is set upright and heated, the solder 17 melts and falls, so the heat pipe 7 can be removed from the cylindrical hole 5 by pressing the heat pipe 7 with an appropriate jig after removing the solder 17. In order to facilitate attachment and detachment of the heat pipe 7, it is desirable that the gap between the cylindrical hole 5 and the heat pipe 7 is large, but it is desirable that the solder 17 be thinner because of its poor thermal conductivity as compared with copper. Therefore, it is desirable to make the gap as small as possible as long as it does not hinder the attaching / detaching operation.

In a general electrophotographic apparatus, the fixing roll 1 is used while being heated to 180 to 200 ° C., and the melting point of the solder 17 is 240 ° C., which is sufficiently higher than this temperature. Therefore, it is possible to prevent the solder 17 from melting during use of the electrophotographic apparatus, and to reliably hold the heat pipe 7 in the cylindrical hole 5. The thickness of the copper pipe constituting the heat pipe 7 is 0.5 mm or more (here, 0.5 mm).
H or 1 / 2H tempered material, the swelling of the heat pipe 7 is suppressed to 0.1 mm or less (when the cylindrical hole 5 is φ6.25 mm) even when heated to 240 ° C. or more. For this reason, it is possible to prevent the heat pipe 7 from being deformed when the solder 17 is melted and the attachment and detachment of the heat pipe 7 being hindered and the flow of the solder 17 being hindered. Further, the melting point of the solder 17 is 300 ° C. or less. Therefore, it is possible to prevent the heat pipe 7 from being plastically deformed by heating when the solder 17 is melted. Therefore, the reuse of the heat pipe 7 can be performed more favorably.

Further, in the fixing roll 1, a space between the heat pipe 7 and the inner wall 5a of the cylindrical hole 5 is filled with a solder 17 having excellent thermal conductivity. For this reason, the function of the heat pipe 7 appears remarkably, and the surface temperature of the fixing roll 1 can be made extremely excellent and uniform. The effect of solder 1
This was confirmed by conducting a comparative experiment with a sample filled with heat transfer silicon instead of 7.

The fixing roll 1 used in the experiment had an outer diameter of 60 m.
m, length: 460 mm, cylindrical hole diameter: 6.25 mm, number of cylindrical holes: 3
A heat pipe 7 having an outer diameter of 6 mm and a length of 450 mm and filled with water is inserted and fixed in a cylindrical hole 5 of the fixing roll 1 while molten solder is injected into the cylindrical hole 5 of the fixing roll 1. did.

As shown in FIG. 5, a halogen heater 21 is provided on only one half of the center axis of the fixing roll 1. Thus, the fixing roll 1 was divided into a heating section heated by the halogen heater 21 and a non-heating section not heated. Next, the observation point A was set at a distance of 100 mm from the ends on the non-heating side and the heating side, respectively.
And B, the temperature difference between points A and B was measured 4 minutes after the halogen heater 21 was energized. The observation points A and B are individually provided on the surfaces of the three heat pipes 7 facing each other, and the temperature difference is measured for each of the heat pipes 7 to measure HP7a, HP7b, and HP7c, respectively.
And Table 1 shows the results.

[0021]

[Table 1]

As shown in Table 1, in this experiment, solder 1
6 fixing rolls 1 filled with the roll 7 (roll N
o. 1-6). In this fixing roll 1, it was found that the temperature difference between AB was as small as 2 to 5 ° C., and that the surface temperature could be extremely favorably uniform. Further, instead of the solder 17, paste-like heat transfer silicon was provided on the outer surface of the heat pipe 7, and two fixing rolls inserted into the cylindrical hole 5 were prepared (roll Nos. 1 'and 2'). In this fixing roll,
It was found that the temperature difference between A and B was 20 ° C. or more, and the surface temperature could not be uniformed very well. Thus, in the fixing roll 1, the solder 1 is placed between the cored bar 3 and the heat pipe 7.
By filling 7, the maintenance cost of the electrophotographic apparatus can be reduced, and the surface temperature can be made very uniform.

It should be noted that the present invention is not limited to the above-described embodiment at all, and can be implemented in various forms without departing from the gist of the present invention. For example, the melting point of the solder 17 may be higher than the operating temperature in the electrophotographic apparatus, and may be 220 to 240 ° C. However, as the melting point of the solder 17 is lower, the temperature of the electrophotographic apparatus needs to be more strictly controlled.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating a configuration of a fixing roll to which the present invention is applied for an electrophotographic apparatus.

FIG. 2 is a cross-sectional view taken along line AA of the fixing roll.

FIG. 3 is a partial cross-sectional view illustrating a configuration of a heat pipe of the fixing roll.

FIG. 4 is a cross-sectional view illustrating a configuration of a fixed portion of the heat pipe.

FIG. 5 is an explanatory diagram illustrating a configuration of a fixing roll used in an experiment.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Fixing roll for electrophotographic apparatus 3 ... Core metal 7 ... Heat pipe 17 ... Solder

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G03G 13/20 G03G 15/20

Claims (2)

(57) [Claims] 1. A hollow cylindrical metal core having a release layer made of a fluororesin provided on an outer surface thereof, and a heat pipe embedded in the metal core in parallel with an axis of the metal core. In the fixing roll for an electrophotographic apparatus, the heat pipe uses a solder that satisfies the following equation.
It is embedded and fixed in the core metal by soldering, and the solder melts.
A fixing roll for an electrophotographic apparatus, which can be sometimes extracted from the core metal . Use temperature of fixing roll <
Melting point <temperature at which the above heat pipe plastically deforms Wherein said heat pipe is formed by a copper pipe which is tempered above 1 / 2H, the solder is, for an electrophotographic apparatus according to claim 1, characterized in that it has a melting point of 240 to 300 ° C. Fixing roll.