JPH05312211A - Bearing for fixing device - Google Patents

Abstract

PURPOSE:To provide a bearing for a fixing device which enables stable fixing. CONSTITUTION:Instead of directly inserting a shaft 5a of a heating roller/ pressure roller 5 into an inner ring 8a of a rolling bearing 8, a bushing 11 having a keyway 11b is fixed to the inner ring 8a of the rolling bearing 8, and the shaft 5a having a key 5b is inserted into the fixed bushing 11. Accordingly. abrasion due to sliding between the shaft 5a and the inner ring 8a as well as excessive load generation on the shaft 5a and the bearing 8 due to excessively tight fitting between the shaft 5a and the inner ring 8a is never caused, and the heating roller/pressure roller 5 are respectively smoothly rotated to apply specified pressure to toner on a recording paper sheet so as to realize stable fixing.

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 a copying machine / printer by electrophotography.

[0002]

2. Description of the Related Art In image formation by electrophotography,
Transfer the toner image formed on the photoconductor to recording paper,
The transferred toner image is fixed on the recording sheet to complete the process. Usually, the fixing device has a structure shown in the sectional view of FIG. 3, and a toner image 2 is formed on a recording paper 1 in the drawing. A heating roller 3 and a pressure roller 3 of the fixing device rotate in the directions of arrows A and B, respectively, and sandwich the recording paper 1 therebetween to feed the recording paper 1 in the direction of arrow C. Since the heater 4 having the heating filament 4a is provided at the axis of the heating roller 3 to heat the heating roller 3, the surface of the heating roller 3 is heated to an appropriate temperature for heat-sealing the toner image 2. Has been done. The surface of the heating roller is coated with a film such as Teflon so that the molten toner does not adhere to it. The pressure roller 5 is made of silicon rubber or the like having heat resistance and appropriate elasticity, and a pressure is generated between the pressure roller 5 and the heating roller with the recording paper 1 sandwiched therebetween. The toner 2 on the recording paper 1 is melted by the heating by the heating roller 3 and penetrates between the fibers of the recording paper 1 by the pressure between the pressure roller 5 and the toner to be fixed. In order to obtain sufficient fixing strength, the pressure between the pressure roller 5 and the heating roller 3 needs to have a large value. Therefore, as the bearings of the pressure roller 5 and the heating roller 3, rolling bearings are used instead of sliding bearings as described below.

FIG. 4 is a sectional view taken along the line XX in FIG. As shown in FIG. 4, the bearing 7 of the pressure roller 5
Is mounted on a substrate 6 and supports a shaft 5a of the pressure roller 5 by a rolling bearing 8. Similarly, the bearing 9 of the heating roller 3 supports the shaft 3a of the heating roller by means of a rolling bearing 10. Although not shown, the bearing 9 is adapted to generate a pressure required for fixing between the bearing 9 and the pressure roller 5 by a pressure generating mechanism such as a spring.

In the conventional fixing device described above, the bearing 7 is used.
Is the outer ring of the rolling bearing 8 and the bearing 9 is the rolling bearing 10
The outer ring is fixed, but in that case, it is necessary to make the fit between the inner ring of the rolling bearing and the shaft a "tight fit". That is, in FIG. 4, the shaft 3 of the heating roller 3 is
"fitting" between a and the inner ring 10a of the rolling bearing 10,
The "fitting" between the shaft 5a of the pressure roller 5 and the inner ring 8a of the rolling bearing 8 needs to be "tight fit". However, in the fixing device, the temperatures of the heating roller 3 and the pressure roller 5 are 180 to 200 ° C., so that the bearing portion of the conventional fixing device has a “clearance fit” at room temperature.
Then, the bearing dimensions were designed so that when the temperature rises to a predetermined temperature, the "tight fit" is achieved.

[0005]

As described above, as the bearing of the conventional fixing device, the rolling bearing is adopted, and the "fitting" between the inner ring of the rolling bearing and the shaft is adjusted to a predetermined temperature. The bearing dimensions were designed so that it would be a "tight fit" when it reached. However, the "fit" between the shaft and inner ring when the specified temperature is reached due to variations in the processing of the bearing dimensions or due to a slight difference in thermal expansion results in a loose "tight fit" or "clearance fit". It may be. It becomes a loose "Shimari fit",
If a "clearance fit" occurs, slippage occurs between the inner ring of the rolling bearing and the shaft, the shaft wears significantly, and a failure occurs in which satisfactory fixing strength cannot be obtained. In order to avoid such an accident, if the "fitting gap" of the "clearance fit" at room temperature is made small or the tight "tight fit" is set, the "fitting" becomes tight due to expansion during heating. There is a problem that abnormal force is applied to the rolling bearing or the shaft to cause a failure such as a misalignment of the shaft center or a tilt of the shaft, wrinkles on the recording paper, and a satisfactory fixing cannot be obtained.

The present invention has been made to solve the above problems, and the bearings of a fixing device in which the inner ring of the rolling bearing and the shaft can operate without abnormality even if there are variations in the processing dimensions and thermal expansion of the heating roller and pressure roller shafts. Is intended to provide.

[0007]

In order to achieve the above object, the present invention provides a fixing device having a heating roller, a pressure roller, and a rolling bearing for axially supporting the heating roller and the pressure roller. A key is provided on each shaft of the roller and the pressure roller, and a bushing having a key groove to be fitted to the key and a hole to be fitted to the shaft is fixed to the inner ring of the rolling bearing, and fixed to the inner ring of the rolling bearing. The shafts of the heating roller and the pressure roller are inserted into the holes of the bushing formed.

[0008]

According to the present invention, the shafts of the heating roller and the pressure roller are not directly inserted into the inner ring of the rolling bearing, but the bushing having the key groove is fixed and fixed to the inner ring of the rolling bearing. The bushing has a structure in which a keyed shaft is inserted, so the shaft and inner ring slip and wear, and the "fitting" between the shaft and inner ring is tight, causing extra load on the shaft and bearing. There is nothing to do.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The entire structure of the fixing device of the present invention is the same as that of the conventional fixing device described with reference to FIGS. This will be described using 1. 1 shows a perspective view of the bearing portion of the pressure roller 5, the bearing portion of the heating roller 3 has the same structure. In FIG. 1, 8 is a rolling bearing having an inner ring 8a. A key 5b is provided in advance on the shaft 5a of the pressure roller 5. Reference numeral 11 is a bushing, which is the shaft 5a.
It has a hole 11a to be fitted with and a key groove 11b to be fitted with the key 5b. The "fitting" between the hole 11a of the bushing 11 and the shaft 5a is made to be a "clearance fit" at room temperature and at the time of heating. Also,
The interference margin is made large so that the "fitting" between the outer diameter of the bushing 11 and the inner ring 8a of the rolling bearing 8 is a "shrink fit" at room temperature and at the time of heating. In assembling the fixing device, the bushing 11 manufactured as described above is press-fitted into the inner ring 8a and fixed, and the shaft 5a is inserted into the hole 11a of the fixed bushing 11. As described above, since the outer diameter of the bushing 11 is tightly "tightly fit" with the inner ring 8a at both normal temperature and heating, the bushing 11 has a tight "tight fit". Due to variations, slippage does not occur between the bushing 11 and the inner ring 8a. Further, since the hole 11a and the shaft 5a are loosely "clearance fit", the rolling bearing or the shaft may be bent or tilted due to an abnormal force applied to the rolling bearing or the shaft due to variations in processing or variations in thermal expansion. Disappeared
Since the key 5b and the key groove 11b prevent rotation between the shaft 5a and the inner ring 8a, the shaft 5a or the inner ring 8a is prevented from being worn by the slip between the shaft 5a and the inner ring 8a.

In the above embodiment, the bushing 11 has a tight "tight fit" so that the outer diameter of the bushing 11 becomes "tight fit" with the inner ring 8a both at room temperature and at heating.
The outer diameter of 1 and the inner ring 8a may be "clearance fit", and an adhesive may be injected into the gap to fix both.

FIG. 2 shows another embodiment of the present invention. A key 5b is provided on the shaft 5a of the pressure roller 5 as in FIG. 1, but the method of fixing the bushing 11 to the inner ring 8a is different from that in FIG. Bushing 11
Is a hole 11a that is fitted with the shaft 5a by "clearance fit",
The point that there is a key groove 11b that fits with the key 5b is the same as in FIG. 1, but the bushing 11 has a flange 11c.
And has a screw hole 11d. FIG. 2 shows the bushing 11.
As shown in (b), it is inserted into the inner ring 8a, the stopper plate 12 is applied, and the inner ring 8a is fixed with screws 13. The shaft 5a is inserted into the bushing 11 thus fixed. See also FIG.
As shown in (b), the outer diameter of the bushing 11 has a taper 1
1e is provided, and when the screw 13 is tightened through the stopper plate 12, the taper 11e has a wedge effect and the inner ring 8 is provided.
Since it bites into a, the fixing between the taper bushing 11 and the inner ring 8a is further improved.

As described above, in the bearing of the fixing device of the present invention,
Instead of directly inserting the heating roller and pressure roller shafts into the inner ring of the rolling bearing, fix the bushing with the key groove to the inner ring of the rolling bearing, and fix it to the fixed bushing.
Since the shaft with a key is inserted, the shaft and inner ring slip and wear, and the "fit" between the shaft and inner ring
It is tight and does not generate extra load on the shaft and bearing.

[0013]

As is apparent from the above embodiments, according to the present invention, the shafts of the heating roller and the pressure roller are not directly inserted into the inner ring of the rolling bearing, but a bushing having a key groove is used for the rolling bearing. Since it has a structure in which it is fixed to the inner ring of the shaft and the shaft with a key is inserted into the fixed bushing, the shaft and the inner ring slip and wear, and the "fit" between the shaft and the inner ring becomes tight. Since the heating roller and the pressure roller rotate smoothly and a predetermined pressure can be applied to the toner on the recording paper without generating extra load on the shaft and the bearing, stable fixing can be performed.

[Brief description of drawings]

FIG. 1 is a perspective view of a bearing of a fixing device according to a first exemplary embodiment of the present invention.

2A is a perspective view of a bearing of a fixing device according to a second embodiment of the present invention, and FIG. 2B is a sectional view of a bearing of the fixing device according to the second embodiment of the present invention.

FIG. 3 is a sectional view of a fixing device of an electrophotographic apparatus.

FIG. 4 is a sectional view of a fixing device having a conventional bearing.

[Explanation of symbols]

 3 heating roller 3a heating roller shaft 5 pressure roller 5a pressure roller shaft 5b key 8 rolling bearing 8a rolling bearing inner ring 11 bushing 11a bushing hole 11b bushing key groove 11c flange 11d screw hole 11e taper

Claims (5)

[Claims] 1. A fixing device having a heating roller, a pressure roller, and a rolling bearing for axially supporting the heating roller and the pressure roller, wherein keys are provided on respective shafts of the heating roller and the pressure roller. A bushing having a key groove to be fitted to a key and a hole to be fitted to the shaft is fixed to the inner ring of the rolling bearing, and the shaft of the heating roller and the pressure roller is fitted to the hole of the bushing fixed to the inner ring of the rolling bearing. Bearing of the fixing device with the inserted. 2. The fitting between the shafts of the heating roller and the pressure roller and the holes of the bushing is a "clearance fit" at room temperature and at the time of heating, and the outer diameter of the bushing and the inner ring of the rolling bearing are fitted together. When the temperature is room temperature and heating
The bearing of the fixing device according to claim 1. 3. The fitting of the inner ring of the rolling bearing and the outer diameter of the bushing into a "clearance fit", and the adhesive is injected into the gap of the "clearance fit" to attach the bushing to the inner ring of the rolling bearing. The bearing of the fixing device according to claim 1, which is fixed. 4. A bushing is provided with a flange and a screw hole, the bushing is inserted into an inner ring of a rolling bearing, and then a screw is screwed into the screw hole of the bushing via a stopper plate.
The bearing of the fixing device according to claim 1, wherein the inner ring is sandwiched between the stopper plate and the bushing. 5. The bushing according to claim 4, wherein an outer peripheral surface of the bushing is a tapered surface, the bushing is inserted into an inner ring of the rolling bearing, and the bushing is fixed to the inner ring of the rolling bearing by a wedge effect of the tapered surface of the bushing. Bearing of fixing device.