JPH0753088Y2 - roll - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a developing roller or the like used in an electrophotographic copying machine or the like.

[Conventional technology]

As one of the developing methods in an electrophotographic copying machine, there is a magnetic one-component developing method with triboelectric charging. As shown in FIG. 3, in this magnetic one-component developing method, a toner containing a small amount of pigment and iron powder is supplied from the toner supplying device 4 to the outer peripheral surface of the developing roller 8 having the cylindrical magnet 7 built-in for development. By adsorbing the adsorbed toner on the surface of the roll 8 and rotating the developing roll 8 with the cylindrical magnet 7 fixed, the layer forming blade 5 is pressed against the outer peripheral surface of the developing roll 8 at a constant pressure.
By frictionally charging the photosensitive drum 1a with an electrostatic latent image previously charged by a charging device by the attraction and repulsive force of the magnetic force of the cylindrical magnet 7 and the electric attraction force. It is a method of developing. In FIG. 3, 12 is a magnetic pole.

The structure of the developing roll used in the magnetic one-component developing method is shown in FIG. That is, the developing roll 8 has a cylindrical roll body 11 made of a non-magnetic material, and a cylindrical magnet 7 having magnetic poles SNSN ... Center shaft 13 that extends through the center of is extended to the left and right, and flange parts 10
a is provided, and the left and right openings of the roll body 11 are closed by the flange 10a. In this case, the flange part 10
The a is attached to the roll main body 11 by a method such as press-fitting caulking or press-fitting adhesion.

[Problems to be solved by the device]

However, when the electrophotographic copying machine incorporating the developing roll 8 as described above is left in a warehouse or the like for a long period of time, the pressure of the layer forming blade pressed against the developing roll 8 causes the development as shown in FIG. As a result of being added to the same position of the roll 8 for a long time, the flange portions 10a at both ends are inclined (twisted) as shown by the broken line in the figure. Therefore, the flange 10
When the electrophotographic copying machine in which a is twisted is operated, there is a problem that the developing roll 8 is shaken and the copied image becomes unclear.

The present invention has been made in view of such circumstances, and an object thereof is to provide a roll capable of eliminating a shaft shake and obtaining a good copy image.

[Means for Solving the Problems]

In order to achieve the above-mentioned object, the roll of the present invention is a roll in which substantially disc-shaped flange portions each having a rotation shaft portion are fitted in the left and right openings of a cylindrical roll body. A cylindrical joint portion is extended from an outer peripheral edge portion of the portion to a substantially central portion between the flange portions with a predetermined gap between the joint portions.

[Action]

That is, this roll uses only the disc-shaped outer peripheral surface of the substantially cylindrical flange portion as in the conventional example, and is not fixed to the inner peripheral surface of the roll main body by adhesion or the like, and From the outer peripheral edge of the disk-shaped flange portion, the cylindrical joint portion is extended to approximately the center portion between the both flange portions, with a predetermined gap between the joint portions, and Not only the outer peripheral surface, but also the outer peripheral surface of the cylindrical joint extending from this is used to fix and support the portion of the inner peripheral surface of the roll main body except for the approximately central portion, with a wide area of the flange. I am trying to do it. Therefore, compared with the conventional example, the portion to be joined to the inner peripheral surface of the roll body becomes very wide, and the force applied to the outer peripheral surface of the cylindrical roll body due to the great increase in this contact area is, so to speak, above. Since the forces are dispersed, the “twisting” as in the conventional example does not occur. As a result, axial blurring does not occur and a good copy image can be obtained.

Next, this invention will be described in detail based on embodiments.

〔Example〕

FIG. 1 shows an embodiment in which the present invention is applied to a developing roll of a magnetic one-component developing method. That is, in the figure,
Reference numeral 25 is a cylindrical roll body made of non-magnetic resin, and has an outer diameter of 21 mm, an inner diameter of 17.8 mm and a length of 280 mm. In addition, the inside diameter of the cylindrical roll body 25 is 16
A cylindrical magnet 7 having a length of mm and a length of 260 mm is arranged. Metallic disc-shaped flange portions 21 are fitted inside the opening edges of both ends of the roll main body 25, and the outer center thereof is
A shaft portion 17 that extends outward is provided coaxially with the roll body 25 so as to project. Then, along the inner peripheral surface of the roll main body 25 from the inner and outer peripheral edge portions of both flange portions 21, a cylindrical joint portion.
18 'is extended to the center of the roll body 25,
It is joined to the inner surface of.

A load is applied to the central portion of the roll 20 while supporting the shaft portions 17 of both ends of the roll 20, and the amount of bending that occurs in the roll 20 at that time is measured, and the same amount of bending measurement is shown in FIG. The conventional roll 8 was used, and the result is shown in FIG. In FIG. 2, the horizontal axis represents the magnitude of the load and the vertical axis represents the amount of bending. According to this result, the amount of bending of the roll 20 shown by the broken line a is considerably smaller than the amount of bending of the roll 8 shown by the solid line b. Also, next, the load is set to 2 kg and the ambient temperature is set to 45 ° C., and the rolls 20 and 8 are set to 120 ° C. in that state.
Left for hours. Then, the flange portions 21,1 of both rolls 20,8
The amount of twisting shaft deviation of the shaft portion protruding from 0a was measured using a dial gauge. As a result, the axial deviation of the shaft portion 17 of the roll 20 is 40 μm, and the axial deviation of the central axis of the roll 8 is 100 μm.
It was m. From this, it can be understood that the roll 20 is less likely to bend than the roll 8 and the shaft portion 17 is less likely to be shaken.

As described above, in the roll 20, since substantially the entire circumferential surface of the roll body 25 is joined to the outer circumferential surfaces of the metallic flange portion 21 and the joining portion 18 ', the flange portion 21 is less likely to be displaced. Therefore, the shaft portion 17 protruding from the outer surface of the flange portion 21 is prevented from being eccentric with respect to the roll body 25. Therefore, when the roll 20 is used as a developing roll for an electrophotographic copying machine or the like, the axial deviation is reduced and a good copied image can be obtained.

[Effect of device]

As described above, in the roll of the present invention, the cylindrical joint portions from the outer peripheral edge portions of both disc-shaped flange portions are provided with a predetermined gap between both joint portions, and the two are formed between the flange portions. It extends almost to the center. Therefore, the force applied to the roll main body from the layer forming blade or the like that is pressed against the outer circumference of the roll main body is supported not only by the outer circumference of the flange portion but also by the joint portion extended from the flange portion. Since a portion of the inner peripheral surface of the roll main body excluding the substantially central portion is supported in a wide area, the above-mentioned force is dispersed. Therefore, for example, even if an electrophotographic copying machine incorporating this is left in a warehouse for a long period of time and long pressure is applied to the same position of the roll body for a long time, the pressure does not cause axial runout (pebbling) of the flange part. . Therefore, the developing roll is less likely to be shaken, and a stable and good copy image can be obtained. Further, since the joint area between the roll main body and the flange portion is large, the roll body does not laterally shift due to vibration or the like. Further, since the roll of this invention comprises the roll body and the flange portion, the number of parts is small,
In addition to simplifying the structure, inventory management and other management aspects are simplified.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view of an embodiment of the present invention, FIG. 2 is a linear diagram showing the result of comparison of the amount of deflection due to the load between the roll and a conventional roll, and FIG. 3 is a magnetic one-component developing method. 4 is a longitudinal sectional view of a conventional developing roll. 18 '... Joint part, 20 ... roll, 21 ... flange part, 25
...... Roll body

Claims (1)

[Scope of utility model registration request] 1. A roll in which substantially circular disc-shaped flange portions each having a rotation shaft portion are fitted in the left and right openings of a cylindrical roll main body, and a cylindrical shape is formed from the outer peripheral edge portions of the both circular disc-shaped flange portions. A roll characterized in that the joint portion is extended to a substantially central portion between the both flange portions in a state where a predetermined gap is provided between the both joint portions.