JP3056817B2 - Fixing device for image forming device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fixing device for an image forming apparatus in which at least one heat pipe is built in a fixing roller.

[0002]

2. Description of the Related Art It is well known that a fixing roller is provided with a heat pipe for uniformly distributing heat to the whole, in addition to a heat source for heating such as a halogen lamp. As a method for incorporating the heat pipe, a fitting tolerance between a heat pipe and a hole provided in a core of a fixing roller for inserting the heat pipe is reduced, and after inserting the heat pipe into the hole, 350 mm is required. Conventionally, heating to about 400 [deg.] C., thereby plastically deforming the material of the heat pipe, and bringing the heat pipe into close contact with the fixing roller.

[0003]

In the above-described fixing roller with a built-in heat pipe, when the fluororesin or the silicone rubber, which is the release layer of the fixing roller, deteriorates, the heat pipe can still be used. Generally, the fixing roller is thrown away with the heat pipe built in, and this is inevitably disadvantageous in terms of cost.

An object of the present invention is to eliminate the above-mentioned disadvantages in a fixing roller having a built-in heat pipe.

[0005]

According to the present invention, an insertion hole for embedding a heat pipe is formed in a core of a fixing roller according to the present invention, and a space between the insertion hole and the heat pipe at room temperature is provided. The problem is solved by setting the tolerance so that a slight gap is formed, and when the temperature is returned to normal temperature after heating, the heat pipe can be taken out of the insertion hole.

In order to solve the above-mentioned problem, the present invention proposes that a heat pipe incorporated in a fixing roller has a larger linear expansion coefficient than a fixing roller.

According to the present invention, in order to solve the above-mentioned problem, both ends of a heat pipe built in a fixing roller are in contact with heat pipe stoppers provided at these both ends at room temperature. Suggest.

Further, according to the present invention, in order to solve the above-mentioned problem, the difference between the inner diameter of the hole provided in the fixing roller for inserting the heat pipe and the outer diameter of the heat pipe is set to 0.0.
It is proposed to form a gap with a length of 5 mm or more and fill the gap with a heat medium.

[0009]

The heat pipe incorporated in the fixing roller is made detachable. This is performed as follows. That is, the coefficient of linear expansion of the heat pipe is set to be larger than the coefficient of linear expansion of the core metal of the fixing roller, so that the heat pipe can be attached and detached at normal temperature. Adhere to the core metal. Alternatively, both ends of the heat pipe are brought into contact with the heat pipe stoppers provided at these positions at room temperature, and the heat pipe is prevented from expanding in the axial direction at the time of heating, and is converted into radial expansion. The pipe and the core of the fixing roller are brought into close contact with each other. Alternatively, a gap is formed by making the difference between the inner diameter of the hole provided in the core of the fixing roller and the outer diameter of the heat pipe 0.05 mm or more, and the gap is filled with a heat medium, so that the heat pipe can be attached and detached. And maintain thermal conductivity.

[0010]

1 and 2, an embodiment of the present invention will be described.

In the fixing device shown in FIGS. 1 and 2,
A fixing roller 1 and a pressure roller 2 are arranged so as to be rotatable while being pressed against each other. 3 is an inlet guide plate, 4 is an outlet guide plate, 5 is a separation claw, and 6 is a thermistor for controlling the heating temperature.

The core of the fixing roller 1 has an inner diameter of 10 to 20.
A halogen lamp 7 is provided in the center hole 1a as a heat source to heat the fixing roller from the inside. Further, a plurality of axial holes 1b are provided at substantially equal intervals in the core metal of the fixing roller, and heat pipes 8 are respectively embedded in these holes. These heat pipes 8 function to absorb variations in the distribution of the heating temperature of the halogen lamp 7 and, therefore, the temperature difference between the paper passing area and the non-paper passing area.

According to the present invention, a tolerance is set between the hole 1b and the heat pipe 8 inserted therein so that a slight gap is formed at room temperature. Is removable. Further, the materials of the heat pipe and the core metal are selected such that the linear expansion coefficient of the heat pipe 8 is larger than the linear expansion coefficient of the core metal of the fixing roller.
For example, it is preferable to use stainless steel or Fe as the core metal of the fixing roller and use Cu or Al as the heat pipe. In addition, both ends of the heat pipe 8 are lightly pressed at normal temperature by stoppers such as a seal 9 and a sealing screw 10 to stop. 11 is a side plate, 12 is a bearing, and 13 is a drive gear.

According to the above-described structure, the gap between the hole 1b of the fixing roller at normal temperature and the heat pipe 8 expands more in the heat pipe 8 in the radial direction and in the axial direction than the hole 1b during heating. The heat pipe 8 is fixed
The heat transfer between the core metal and the heat pipe is performed satisfactorily with the metal core. When both ends of the heat pipe are stopped by the stopper, the expansion of the heat pipe in the axial direction is prevented at the time of heating, and the heat pipe is converted to its radial expansion, whereby the heat pipe is brought into close contact with the core metal. At normal temperature, the expansion returns to its original state, and a gap is formed again, so that the heat pipe 8 can be easily attached and detached. In this case, the hole 1b
It is necessary to select the tolerance of the gap formed between the heat pipe 8 and the heat pipe 8 in a range where the material of the heat pipe 8 does not undergo plastic deformation during thermal expansion.

Further, as another embodiment, the hole 1b
A gap formed between the heat pipe 8 and the heat pipe 8 is not lost due to thermal expansion at the time of heating, and a liquid can be sealed as a heat medium in this gap. Since the transfer of heat in this case is performed using the liquid as an intermediary, the gap is preferably narrow. Therefore, in the embodiment of the present invention, the difference between the inner diameter of the hole 1b and the outer diameter of the heat pipe 8 is 0.05 to 0.2 mm.
And the gap is filled with liquid. As the liquid, oils such as silicone oil are preferable in consideration of lubrication at the time of attachment and detachment. Hole 1 where heat pipe 8 is inserted
Both ends of b are sealed as follows. At one end, a sealing member is press-fitted and welded. At the other end,
After inserting the heat pipe, the liquid is injected, and the sealing pin is screwed in to seal. In this case, when a sealing material is used as a member for assisting the sealing of the sealing pin, a heat-resistant elastic material, for example, fluorine rubber or the like is used.

[0016]

According to the present invention, a heat pipe is fixed to a fixing pipe.
Since the heat pipe was removably mounted on the core metal, the heat pipe could be reused, and a low-cost fixing roller could be manufactured.

According to the present invention, when the coefficient of linear expansion of the heat pipe is set to be larger than the coefficient of linear expansion of the core metal of the fixing roller, the heat pipe detachably mounted with a gap may be attached to the core of the fixing roller when heated. It is in close contact with gold, and heat conduction between the heat pipe and the fixing roller is reliably performed.

According to the present invention, when the both ends of the heat pipe incorporated in the fixing roller are brought into contact with the heat pipe stoppers provided at these positions at normal temperature, the heat pipe at the time of heating is used. By preventing the expansion in the axial direction and converting the expansion into the radial direction, the heat pipe is brought into close contact with the core metal of the fixing roller, and heat conduction between the heat pipe and the fixing roller is easily performed. Become like

According to the present invention, when a diameter difference is provided between the heat pipe and the hole of the core metal of the fixing roller into which the heat pipe is inserted, and when the gap is filled with oil as a heat medium, the heat pipe is attached and detached. As much as possible, the thermal conductivity can be maintained.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a fixing device according to the present invention.

FIG. 2 is a cross-sectional view of the fixing device shown in FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Fixing roller 1a Halogen lamp insertion center hole 1b Heat pipe insertion axial hole 7 Halogen lamp 8 Heat pipe

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Atsushi Arai 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Co., Ltd. (72) Inventor Yutaka Fukuchi 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Co., Ltd. (72) Inventor Masahiko Sato 1-3-6 Nakamagome, Ota-ku, Tokyo (56) Inside Ricoh Co., Ltd. Reference: Shokai 58-38165 (JP, U) Shokai Sho56- 137163 (JP, U) (58) Field surveyed (Int. Cl. ⁷ , DB name) G03G 15/20 301

Claims (4)

(57) [Claims] In a fixing device of an image forming apparatus having at least one heat pipe built in a fixing roller, an insertion hole for embedding the heat pipe is formed in a core metal of the fixing roller. A tolerance is set so that a slight gap is formed at normal temperature between the heat pipe and the heat pipe, and the structure is such that the heat pipe can be taken out of the insertion hole when it returns to normal temperature after heating. A fixing device. 2. The fixing device according to claim 1, wherein a linear expansion coefficient of a heat pipe built in the fixing roller is larger than a linear expansion coefficient of a core metal of the fixing roller. 3. The heat pipe according to claim 1, wherein both ends of the heat pipe incorporated in the fixing roller are in contact with the heat pipe stoppers provided at the both ends at room temperature. Fixing device. 4. A gap is formed with a difference between an inner diameter of a hole provided in a core of a fixing roller for inserting the heat pipe and an outer diameter of the heat pipe being 0.05 mm or more, and a heat medium is formed in the gap. The fixing device according to claim 1, wherein the following condition is satisfied.