JPH09222815A - Fixing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To shorten startup time, obtain a reinforcing effect of reinforcing members, and improve workability of a fixing roller by specifying a shape of an outside edge part where the reinforcing members engage with an inner wall of the fixing roller. SOLUTION: Reinforcing members 3a and 3b formed in a ring shape having a cylindrical flat part 5 in an outside edge part, and are formed in a dimension such as its cylindrical flat part 5 and an inner wall of core metal 1a can engage with each other in an integrally fastened-fitted condition, and are also fixed to a fixing roller 1 by performing spot welding 6 on plural places of the cylindrical flat part 5. Falling-down and falling-off of the reinforcing members 3a and 3b can be prevented, and even if pressurizing force is large, the reinforcing members 3a and 3b do not move inside the fixing roller 1, and they are effective not only in preventing a shaft directional collapse of the fixing roller 11 but also in preventing deflection. A temperature rise in the fixing roller 1 is not hindered, and deformation and damage at machine work time or heated time are eliminated, and productivity, durability and stability of the fixing roller 1 can be improved.

Description

Detailed Description of the Invention

[0001]

The present invention relates to a fixing device for an image forming apparatus.

[0002]

2. Description of the Related Art Recently, a fixing device having a short rise time has been desired from the viewpoint of power saving, and it is achieved to achieve this.
As one of the means, a fixing roller in which the core metal of the fixing roller is formed of a thin metal and has a small heat capacity and a short rise time is being used. As shown in FIG. 10, such a fixing device has a fixing roller 1 having a heater 10 therein, and a pressure roller 2 in pressure contact with the fixing roller 1. The material of the core metal 1a of the fixing roller 1 is , Al, Fe, etc., which are well balanced in terms of thermal conductivity, mechanical strength, and cost, are used, and the wall thickness is about 0.3 to 0.8 mm.
The outer diameter of the core metal 1a is about 20 to 40 mm.

In the above-mentioned one, the fixing roller 1
Since the core metal 1a of 1 is thinned, the mechanical strength is insufficient, and as shown in FIG.
As exaggeratedly shown in FIG. 12, crushing of the cross-section occurs, and these deformations cause improper fixing or damage of the fixing roller 1 when extreme deformation occurs. Also,
The outer diameter accuracy of the fixing roller 1 is required to be high in order to ensure the fixing property and the transportability, and it is extremely difficult to machine a thin-walled metal core pipe having a low mechanical strength, especially the outer diameter turning, There is a problem that the fixing roller 1 is easily deformed by the tool pressure during grinding and cutting of the roller 1 and the productivity is significantly impaired. Therefore, as a measure for solving this problem, as shown in FIG. 13, a reinforcing member 3 ′ formed in a ring shape in the fixing roller 1 and a support rod 9 supporting the reinforcing member 3 ′ are provided in the fixing roller 1. A roller provided inside the fixing roller 1 with an increased mechanical strength is disclosed in JP-A-61-59381 and is publicly known.

However, in the above-mentioned one, it causes a large increase of the heat capacity and delays the temperature rise of the fixing roller 1, and the support rod 9 for preventing the bending of the fixing roller 1 is the heater 10. There is a problem in that the heat generated from the fixing roller 1 is blocked, and the fixing roller 1 has uneven temperature. As a measure for solving this problem, although not shown, it is proposed to remove the support rod and fix the ring-shaped reinforcing member to the fixing roller in a tight fit state.

[0005]

The above-mentioned reinforcing member which is fixed to the conventional fixing roller in a tightly fitted state requires high precision and requires a high degree of skill in the loading operation. The rise occurs not only during actual use, but also during mechanical processing (cutting, grinding, etc.) of the fixing roller, when coating the Teflon resin that is the heat-resistant release layer on the surface of the fixing roller, and when coating the inner surface of the roller. When the fixing roller is thermally expanded, the tight fitting state of the reinforcing member may loosen and fall off, and when the pressure roller is pressed, if the applied pressure is large, cracks occur as shown in FIG. (A) causes breakage, or a gap is formed in a part of the contact surface between the fixing roller and the reinforcing member, and a thrust force for moving to either end is generated, so that the reinforcing member acts as a fixing roller. Reinforcing effect by sliding on the inner circumference and moving Since the fixing roller is deformed and the fixing roller is deformed, the fixing roller has a problem that the fixing roller has low cost and sufficient mechanical strength, and a fixing device that does not deform cannot be easily obtained.

Therefore, an object of the present invention is to solve the problems of the conventional fixing device as described above, to improve the workability of the fixing roller because the rising time is fast and the reinforcing effect of the reinforcing member is obtained. The present invention is to provide a fixing device which can be manufactured at low cost without deformation of the fixing roller and has sufficient mechanical strength and durability.

[0007]

SUMMARY OF THE INVENTION In order to achieve the above-mentioned object, the present invention provides a fixing device having a reinforcing member inside a fixing roller. Is formed in a ring shape having a cylindrical flat portion on the outer edge portion which engages with the inner wall of the fixing roller, and the fixing roller and the cylindrical flat portion are spot-welded. In the invention according to claim 2, spot welding is
It is characterized in that it is provided at a plurality of positions that are evenly divided with respect to the entire circumference. In the invention according to claim 3, the cylindrical flat portion is divided by providing a plurality of slits in the axial direction, and the spot welding between the fixing roller and the cylindrical flat portion is uniform over the entire circumference. It is characterized in that it is provided at a plurality of divided positions. Claim 4
The invention described in (1) is a fixing device having a reinforcing member inside the fixing roller, characterized in that a member for preventing the movement of the reinforcing member is provided inside the fixing roller. According to a fifth aspect of the present invention, there is provided a fixing device including a reinforcing member inside a fixing roller, wherein an outer edge portion of the reinforcing member engaging with the fixing roller is formed in a ring shape having a cylindrical flat portion, and fixing is performed. In the roller central portion, two reinforcing members are provided so that the cylindrical flat portions face in opposite directions.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION In the embodiments of the present invention shown in FIGS. 1 to 9, the same parts as those of the above-mentioned conventional ones will be referred to by the same reference numerals, and the description thereof will be omitted. The first embodiment of the present invention is as shown in FIG. 1. In the thin fixing roller 1, a release layer (not shown) formed of a heat-resistant release material such as Teflon is formed on the surface of the core metal 1a. The core metal 1a is made of Al, which has a good balance of thermal conductivity, mechanical strength, and cost.
Fe or the like is used, and the wall thickness is about 0.3 to 0.8 mm. The outer diameter of the core metal 1a is about 20 to 40 mm, and the reinforcing members are attached to the central portion and three end portions.
The material of the central reinforcing member 3a and the end reinforcing member 3b is the same as that of the cored bar 1a, or the coefficient of thermal expansion thereof is at least the same as or slightly larger than that of the cored bar 1a. In addition, 11 is a central heater having a heat generating portion corresponding to small-sized paper, 12 is an end heater that supplies heat to a portion other than the central heater, 13 is a heat insulating bush, 14 is a bearing, 15a, 15b is a fixing side plate, and 16 is a gear.

The temperature of the fixing roller 1 rises not only during actual use but also during mechanical processing (cutting, grinding, etc.) of the fixing roller 1.
Since it occurs when coating the Teflon resin, which is a heat-resistant release layer on the surface of the fixing roller 1, or when coating the inner and outer surfaces of the roller 1,
In order to prevent workability and productivity of the fixing roller 1 from being damaged, coming off, and moving of the fixing roller 1, the coefficient of thermal expansion of the reinforcing member is set to be the same as or slightly larger than that of the fixing roller 1.

As shown in FIGS. 2 to 4, the reinforcing member 3a (3b) is formed in a ring shape having a cylindrical flat portion 5 on the outer edge thereof, and the cylindrical flat portion 5 and the inner wall of the core metal 1a. The dimensions are such that and can be engaged with each other in a fitted state, and further, spot welding 6 is performed at a plurality of positions of the cylindrical flat portion 5 to fix the fixing roller to the fixing roller.

Further, the mounting position of the reinforcing member 3a (3b) to the fixing roller 1 is the central portion (a) of the sheet passing width, which is the position where the force is most applied when the pressure roller 2 is pressed against the fixing roller 1. , Three locations near the fixing roller front and rear support portions (bearing portions b) near both ends.

In such a structure, the reinforcing member 3a
(3b) can be prevented from collapsing or falling off, and the reinforcing member 3a (3b) does not move inside the fixing roller 1 even when the pressing force is large, so that the fixing roller 1 can be prevented from being crushed in the axial direction. The fixing roller 1 is effective in preventing flexure.
The temperature of the fixing roller 1 is not hindered, and the fixing roller 1 is not deformed or damaged during machining or when it is heated, thereby improving productivity, durability, and stability of the fixing operation. You can

The second embodiment differs from the first embodiment in that
By removing the reinforcing members 3b at both ends, as shown in FIG. 5, the fixing member 3a is attached only to the central portion of the fixing roller 1, and the both ends are subjected to the drawing process B so that the diameter is smaller than the central portion. is there. Even with this configuration, the strength of the fixing roller 1 that is almost the same as that of the first embodiment can be obtained, and the same quality can be obtained.

The third embodiment differs from the first embodiment in that
As shown in FIG. 4, the circumference of the fixing roller 1 is evenly divided, and spot welding 6 is applied to a plurality of places to reinforce the reinforcing member 3a (3).
b) is attached. The spot welding points are not limited to the four points shown in FIG. 4, but may be a plurality of points and may be positions equally divided with respect to the circumference of the fixing roller 1.

In such a structure, when the fixing roller 1 is rotated, compressive stress acts on the spots on the inner surface of the fixing roller 1 and the outer surface of the flat portion of the reinforcing member immediately before passing through the nip position, and the fixing roller 1 Although a tensile stress acts when passing the horizontal position with respect to 1 and a shear stress acts at other positions, cracks occur on the peripheral surface of the reinforcing member 3a (3b) because such stress is evenly received. And will not be damaged.

The fourth embodiment differs from the first embodiment in that
As shown in FIG. 6, the cylindrical flat portion 5 of the reinforcing member 3 a (3 b) is provided with a plurality of slits 7 that divide the reinforcing member 3 a (3 b) evenly in the axial direction, and the cylindrical flat portion 5 divided by the slits 7. Each of the central portions of the fixing roller 1 and the fixing roller 1 are spot-welded 6 and the reinforcing member 3a (3b) is fixed to the fixing roller 1.
It is attached to.

In such a structure, the reinforcing member 3a
The mechanical strength of (3b) can be maintained and the strength of the fixing roller 1 can be increased, and the reinforcing member 3a (3
Reinforcing member 3a when loading b) onto the inner surface of the fixing roller 1
The outer diameter accuracy of (3b) can be set more gently than that without a slit, and the thrust load resistance can be reduced to facilitate the loading work, and the cylindrical flat portion 5 divided into a plurality of parts can be fixed. The adhesion with the inner surface of the roller 1 can be easily ensured, the spot welding 6 can be reliably performed, and the reinforcing member 3a (3b) can be manufactured by drawing a sheet metal, so that the reinforcing member 3a (3b) can be manufactured. It is possible to obtain the fixing roller 1 that can be manufactured at low cost, has high accuracy, increases mechanical strength, is significantly improved in productivity, and is low in cost.

The fifth embodiment differs from the first embodiment in that
A stopper member 8 for preventing movement of the reinforcing member 3a (3b) is provided on the bending side 5'of the cylindrical flat portion 5 of the reinforcing member 3a (3b) as shown in FIGS.

The material of the stopper member 8 is preferably the same as that of the core metal 1a in view of thermal expansion, and it is formed so as to be a part of an arc according to the curvature of the inner surface of the fixing roller 1 and spot welded 6 '. And is fixed to the fixing roller 1. It is sufficient that the thickness of the stopper member 8 is equal to or less than the thickness of the core metal 1a, and a plurality of stopper members 8 are provided at even positions with respect to the circumference of the fixing roller 1.

In such a case, when the fixing roller 1 is pressed and rotated, the reinforcing member 3a (3b) is prevented from moving in the bending direction of the cylindrical flat portion 5 due to the thrust force. The spot welding process for mounting the reinforcing member 3a (3b) can be simplified and the temperature rise of the fixing roller 1 is not hindered.

The sixth embodiment differs from the fifth embodiment in that
Using the fixing roller 1 whose both ends are drawn (B), the stopper member 8 is removed, and the two reinforcing members 3c and 3d are
As shown in FIG. 9, the fixing roller 1 is mounted on the central portion of the fixing roller 1 so that the cylindrical flat portions 5 face each other and face each other outward. In such a case, when the two reinforcing members 3c and 3d are loaded in the central portion of the fixing roller 1, one by one is inserted from both ends of the fixing roller 1 from the bending side of the cylindrical flat portion 5. It can be done easily.

In such a case, the thrust force of the reinforcing members 3c and 3d generated by the pressure of the pressure roller 2 can be offset, and the reinforcing members 3c and 3d do not move, so that the spot The process of welding 6 can be omitted and the mounting process can be simplified.

[0023]

As described above, according to the invention described in claim 1, in the fixing device, the ring having the cylindrical flat portion at the outer edge portion where the reinforcing member engages with the inner wall of the fixing roller. Since the fixing roller and the cylindrical flat portion are spot-welded, the rise time is fast, the reinforcing effect of the reinforcing member is obtained, and the workability of the fixing roller can be improved. The roller is not deformed, the cost is low, and a fixing device having sufficient mechanical strength and durability is obtained. According to the second aspect of the present invention, since the spot welding is provided at a plurality of positions that are evenly divided with respect to the entire circumference, the strength of the fixing roller is significantly improved, and the reinforcing member is provided to the fixing roller. Can be reliably loaded, and there is an effect that the reinforcing member does not move or break. In the invention according to claim 3, the cylindrical flat portion is divided by providing a plurality of slits in the axial direction, and the spot welding between the fixing roller and the cylindrical flat portion is uniform over the entire circumference. Since it is provided in multiple divided positions, the strength of the fixing roller is greatly improved, and the processing and mounting of the reinforcing member is reliable and easy, and the reinforcing member does not move or break. The fixing roller is not deformed at a low cost, and a fixing device having sufficient mechanical strength and durability can be obtained.
According to the invention of claim 4, in the fixing device, since the member for preventing the movement of the reinforcing member is provided in the fixing roller, the strength of the fixing roller is significantly improved, and spot welding is not necessary, so that the processing step is performed. The fixing member can be securely attached to the fixing roller, the reinforcing member does not move or break, the fixing roller does not deform, and the cost is low. There is an effect that a fixing device having a desired strength and durability can be obtained. According to a fifth aspect of the invention, in the fixing device, the outer edge portion of the reinforcing member that engages with the fixing roller is formed in a ring shape having a cylindrical flat portion, and two reinforcing members are provided in the central portion of the fixing roller. Since the cylindrical flat parts are provided in opposite directions, the strength of the fixing roller is significantly improved, and spot welding is not required, which reduces the number of processing steps and prevents the reinforcing member from moving or being damaged. There is an effect that the fixing roller is not deformed, does not occur, is low in cost, and a fixing device having sufficient mechanical strength and durability can be obtained.

[Brief description of drawings]

FIG. 1 is a schematic vertical sectional view of a first embodiment of the present invention.

FIG. 2 is a vertical cross-sectional view of the reinforcing member of the first embodiment.

FIG. 3 is a front view of the reinforcing member of the above-described first embodiment.

FIG. 4 is a perspective view of a reinforcing member according to the first and third embodiments of the above, and is a view showing a position of spot welding.

FIG. 5 is a schematic vertical sectional view of a fixing roller according to a second embodiment of the above.

FIG. 6 is a perspective view of a reinforcing member according to a fourth embodiment of the above.

FIG. 7 is a longitudinal sectional view of an essential part of a fifth embodiment of the above.

8 is a vertical cross-sectional view taken along line YY of FIG.

FIG. 9 is a schematic vertical sectional view of a fixing roller according to a sixth embodiment of the present invention.

FIG. 10 is a schematic longitudinal sectional view of a conventional fixing device.

FIG. 11 is a diagram showing a bending state of the above fixing roller.

FIG. 12 is a diagram showing a collapsed state of the above fixing roller.

FIG. 13 is a schematic vertical sectional view of a fixing device having the same reinforcing member.

FIG. 14 is a view showing a damaged state of the reinforcing member of the above.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Fixing roller 2 Pressure roller 3a, 3b, 3c, 3d Reinforcing member 4 Outer edge 5 Cylindrical flat part 6 Spot welding 7 Slit 8 Stopper member

Front Page Continuation (72) Inventor Jun Yura 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Co., Ltd.

Claims (5)

[Claims] 1. In a fixing device having a thin fixing roller and a pressure roller that comes into pressure contact with the fixing roller, and a reinforcing member is provided inside the fixing roller, the reinforcing member engages with an inner wall of the fixing roller. A fixing device, wherein the fixing roller is formed in a ring shape having a cylindrical flat portion at an outer edge portion, and the fixing roller and the cylindrical flat portion are spot-welded. 2. The fixing device according to claim 1, wherein the spot welding is provided at a plurality of positions that are evenly divided with respect to the entire circumference. 3. The cylindrical flat portion is divided by providing a plurality of slits in the axial direction, and the spot welding between the fixing roller and the cylindrical flat portion is divided into a plurality of portions evenly divided with respect to the entire circumference. The fixing device according to claim 1, wherein the fixing device is provided at a position. 4. A fixing device having a thin fixing roller and a pressure roller that comes into pressure contact with the fixing roller, and a reinforcing member inside the fixing roller, wherein movement of the reinforcing member is prevented in the fixing roller. A fixing device comprising a member. 5. An outer edge portion of a reinforcing member engaging with the fixing roller in a fixing device having a thin fixing roller and a pressure roller in pressure contact with the fixing roller and having a reinforcing member inside the fixing roller. Is formed in a ring shape having a cylindrical flat portion, and two reinforcing members are provided in the central portion of the fixing roller with the cylindrical flat portions facing in opposite directions, respectively.