JP2010243278A - Hardness measuring method of elastic body roller - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a hardness measuring method of an elastic body roller having higher accuracy, based on the actual use of the elastic body roller. <P>SOLUTION: The hardness measuring method of the elastic body roller provided with an elastic body layer on the outer periphery of a core metal includes processes for setting a shaft of a rotatable cylindrical member parallel with a shaft of the elastic body roller; inserting the cylindrical member into the elastic body layer so that the elastic body layer is deformed by the cylindrical member, while the parallelism of the two axes is maintained ; rotating the cylindrical member in subordinate manner with respect to the rotating elastic body roller, while the elastic body roller is rotatated with a fixed shaft interval between the cylindrical member and the elastic body roller; electrically converting a load applied to the cylindrical member, and measuring the hardness. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a method for measuring the hardness of an elastic roller. In particular, the present invention relates to a method for measuring the hardness of an elastic roller having an elastic layer used in an image forming apparatus such as a copying apparatus, an image recording apparatus, a printer, or a facsimile.

  An elastic roller having an elastic layer is often used in contact with another member as in the case of being used as an electrophotographic roller. For example, the toner supply roller is used in contact with a toner carrier at a constant axis interval in the developing device. In this case, the toner supply roller is required to have two functions, that is, a function of supplying toner to the toner carrier and a function of peeling off undeveloped toner from the toner carrier.

  The hardness of the elastic roller having the elastic layer has a large influence on the image. For example, when the toner supply roller having high hardness is in contact with the developing roller, damage to the toner is large, and the image is fogged. (For example, refer to Patent Document 1). Further, when there is unevenness in hardness in the circumferential direction of the elastic roller, the image is shaded.

  Conventionally, as a method for measuring the hardness of an elastic roller having an elastic body layer, Asker A, C, or the like is used for those having high to medium hardness. In addition, a low hardness elastic roller such as a toner supply roller having an elastic layer of urethane foam is measured by an original measuring method such as Asker F or measuring hardness at a constant deformation (for example, Patent Documents). 2).

  In addition, many of the elastic rollers are not only used with a constant pressure or a fixed amount of intrusion with other members, but are often used while rotating the axial distance between the elastic roller and the other members as a constant interval. Up to now, the hardness measurement in the circumferential direction of the elastic roller has been set as the hardness by measuring the load per unit penetration amount by letting the plate-shaped jig penetrate a certain amount into the elastic layer without rotating, and measuring the load per unit penetration amount. For example, see Patent Document 1). However, as an actual method of using the elastic roller, for example, the toner supply roller is inserted into the toner carrier at a constant axial interval and is rotated. Therefore, in spite of actual changes in penetration and hardness due to outer diameter fluctuation, these have not been taken into account in the conventional hardness measurement method.

Japanese Patent No. 3881719 JP 2001-290363 A

  An object of the present invention is to provide a more accurate method for measuring the hardness of an elastic roller in line with the actual use of the elastic roller.

The method for measuring the hardness of an elastic roller according to the present invention includes:
In the hardness measurement method of the elastic body roller provided with the elastic body layer on the outer periphery of the core metal,
A step of making the axis of the rotatable cylindrical member parallel to the axis of the elastic roller;
Intruding the cylindrical member into the elastic layer so that the elastic layer is deformed by the cylindrical member while maintaining the parallelness of the two axes;
A step of rotating the cylindrical member passively with respect to the rotating elastic roller while rotating the elastic roller with a constant axial distance between the cylindrical member and the elastic roller;
A step of measuring hardness by electrically converting a load applied to the cylindrical member;
It is characterized by having.

  Further, the elastic layer is a foamed elastic layer.

In the step of intruding the cylindrical member into the elastic layer,
When the average radius of the elastic roller before the hardness measurement is 100%, the radial distance of the elastic roller after the cylindrical member enters is 65% or more and 95% or less of the average radius of the elastic roller. As described above, the distance between the two shafts of the cylindrical member and the elastic roller is set.

Further, the means for measuring the hardness by electrically converting the load applied to the cylindrical member continuously converts the pressure when the cylindrical member enters the elastic roller into an electric signal through the load cell. Means to measure,
The load is measured at least at eight points or more on the outer circumference of the elastic roller.

  Further, the hardness measurement is performed at three or more axial positions of the elastic roller.

  The elastic roller evaluation method according to the present invention is characterized in that the elastic roller used in the image forming apparatus is evaluated using the hardness measurement method.

  According to the present invention, a more accurate hardness measurement method is provided in accordance with the actual use of an elastic roller than the conventional method of measuring hardness with a constant penetration amount without taking into account the outer diameter fluctuation of the elastic roller. can do.

It is the schematic which shows an example of the hardness measuring method of this invention. It is sectional drawing which shows the penetration | invasion to the elastic body layer of a cylindrical member. It is the schematic seen from the elastic body roller longitudinal direction which shows the conventional hardness measuring method. It is the schematic seen from the elastic body roller axial direction which shows the conventional hardness measuring method.

The present invention is a method of measuring the hardness of an elastic roller provided with an elastic layer on the outer periphery of a metal core,
A step of making the axis of the rotatable cylindrical member parallel to the axis of the elastic roller;
Intruding the cylindrical member into the elastic layer so that the elastic layer is deformed by the cylindrical member while maintaining the parallelness of the two axes;
A step of rotating the cylindrical member passively with respect to the rotating elastic roller while rotating the elastic roller with a constant axial distance between the cylindrical member and the elastic roller;
A step of measuring hardness by electrically converting a load applied to the cylindrical member;
And a method for measuring the hardness of the elastic roller.

  The inventors of the present invention have made it difficult to measure the hardness of the elastic roller, which is effective for evaluating the elastic properties of the elastic roller, taking into account changes in the amount of penetration and hardness due to the outer diameter deflection of the elastic roller. I found a way. The hardness measurement method of the elastic roller in the present invention is a member of an image forming apparatus such as a toner supply roller, as compared with the conventional hardness measurement method with a constant penetration amount that does not take into account the outer diameter fluctuation of the elastic roller. It is in line with the actual use when used as. As a result, it has been found that the measurement value obtained by the method of the present invention has a good correlation with the image evaluation result obtained by the image shaper. Hereinafter, although an embodiment of the present invention is described, the present invention is not limited to this.

(About the hardness measurement method according to the present invention)
First, a method for measuring the hardness of an elastic roller according to the present invention will be described with reference to the drawings.

  FIG. 1 is a schematic view showing an example of a method for measuring the hardness of an elastic roller in the present invention. The elastic body roller 1 includes a core metal 2 and an elastic body layer 3 provided on the outer periphery of the core metal 2. The elastic roller 1 is attached to a roller rotation mechanism (not shown) of the hardness measuring device 6. The cylindrical member 4 is caused to enter the elastic body layer 3 of the elastic body roller 1 and the elastic body roller 1 is rotated, so that the cylindrical member 4 is driven and rotated. The load applied to the cylindrical member 4 during this rotation is electrically converted by the load cell 5 to measure the hardness. In addition, the unit comprised from the cylindrical member 4, the jig 8, and the load cell 5 is represented as the hardness measuring device 6 here.

  In the hardness measurement method according to the present invention, the hardness at one location may be measured for one elastic roller 1 which is a measurement object, or as shown in FIG. You may measure the hardness in several places simultaneously. When simultaneously measuring the hardness at a plurality of locations, a plurality of cylindrical members 4 may be inserted into the elastic roller 1 with a mechanism (not shown) connecting a plurality of load cells 5 to measure the hardness. When higher accuracy is required, it is preferable to measure the hardness at least at three or more measurement points in the axial direction of the elastic roller.

  FIG. 2 is a sectional view in a plane perpendicular to the axes of the elastic roller 1 and the cylindrical member 4 of FIG. As a method for measuring the hardness of the elastic roller 1 in the present invention, first, as shown in FIG. 2, the cylindrical member 4 is arranged so that its axis is parallel to the axis of the elastic roller 1. The interval with the shaft of the elastic roller 1 is reduced. The cylindrical member 4 is inserted so that the elastic body layer 3 is deformed, and is fixed so that the axial distance A between the shaft of the cylindrical member 4 and the shaft of the elastic roller 1 is a predetermined distance. A method for setting the axis interval A to a predetermined interval is not particularly limited. For example, there is no time for enumerating, such as a mechanism that allows both shafts to be sandwiched and the distance between both shafts to be adjusted by screw rotation.

  Further, when the average radius R1 (not shown) of the elastic roller 1 before the hardness measurement is 100%, the radial distance R2 (see FIG. 2) of the elastic roller 1 after entering the cylindrical member 4 is the elastic roller 1. It is preferable to set the cylindrical member 4 in the elastic roller 1 so that the average radius R1 is 65% or more and 95% or less. Hereinafter, the ratio of the radial distance R2 of the elastic body roller 1 after entering the cylindrical member 4 to the average radius R1 of the elastic body roller 1 before the hardness measurement is referred to as an intrusion rate (%). When the penetration rate exceeds 95%, the influence of the outer diameter fluctuation of the elastic roller 1 and the surface shape, for example, unevenness, is large, and the effect of evaluating the hardness of the elastic layer 3 may not be sufficiently exhibited. On the other hand, if it is less than 65%, the deformation of the elastic layer 3 is large, and the elastic roller 1 may be damaged by this hardness measurement. Further, the influence of the deflection of the cored bar 2 of the elastic roller 1 may be increased. Furthermore, the hardness of the elastic body layer 3 and the impact resilience are large, and the numerical value of the hardness of the elastic body roller 1 may appear small. More preferably, it is 75% or more and 90% or less. More preferably, the intrusion rate is the same as that of a member that enters and abuts when the elastic roller is actually used.

  The cylindrical member 4 is connected to a load cell 5 which is a hardness detector via a jig 8 connected to both ends of the shaft. The jig 8 is usually manufactured using a metal such as a general steel material or a stainless steel material. One end of the cylindrical member 4 is connected to both ends of the shaft of the cylindrical member 4 in such a configuration that a smooth slippage of the cylindrical member 4 can be secured. The other end is connected to the load cell 5. The configuration of the jig 8 is not particularly limited as long as the jig 8 has a structure capable of transmitting information on the load applied to the cylindrical member 4 to the load cell 5 without excess or deficiency. Information regarding the load applied to the cylindrical member 4 transmitted by the jig 8 is detected by the load cell 5, continuously converted into an electric signal, transmitted to a recording device (not shown) by the cable 7, and recorded.

  As the rotational speed of the elastic roller 1 at the time of measurement, an appropriate rotational speed corresponding to the characteristics required according to the purpose of use of the elastic roller 1 that is a measurement object may be selected, and preferably the elastic roller 1 The rotation speed is 5 rpm or more and 60 rpm or less. If it exceeds 60 rpm, noise accompanying rotation may be easily detected as hardness. On the other hand, if it is less than 5 rpm, the measurement time becomes long.

  The load measurement may be performed by measuring the required number of points at a necessary location in accordance with the rotational speed of the elastic roller 1. However, it is preferably at least 8 points on the outer circumference of the elastic roller 1 in the circumferential direction. If the number of points is less than 8, the amount of data is too small, and unevenness in hardness on the outer periphery of the elastic roller 1 (hereinafter referred to as peripheral hardness unevenness) may not be accurately measured. More preferably, it is 50 points or more. Further, since the rotation speed is not stable at the initial stage of rotation of the elastic roller 1, it is preferable to use at least the data after the second round. In addition, although the place of eight or more points in the circumferential direction may be an arbitrary position on the circumference of the elastic roller, it is preferably a place where the circumference of the elastic roller is measured at a substantially uniform angle.

  The recording device that records the electrical signal from the load cell 5 is not particularly limited as long as it can record the hardness over a predetermined measurement time, and is suitable for the present invention from among known recording devices. What is necessary is just to select and use. For example, “PCD-300A” (trade name) manufactured by Kyowasha and the like can be mentioned.

  The measured load data may be recorded continuously as analog data, or the load data detected by the load cell 5 and converted into an electrical signal may be recorded in the recording device as non-continuous digital data. Good. Further, the digital data may be recorded in the recording device periodically or aperiodically.

  The load may be converted as necessary. For example, the load is divided by the contact area between the cylindrical member 4 and the elastic layer 3 to be converted per unit contact area, or the load is divided by the intrusion volume into the cylindrical member 4 and the elastic layer 3. It may be converted per unit penetration volume.

(About the elastic roller rotating mechanism according to the present invention)
The elastic roller rotation mechanism (not shown) is not particularly limited as long as it can rotate the elastic roller 1 around the central axis at a predetermined constant rotation speed. Therefore, what is suitable for the present invention may be selected and used. For example, motor rotation is generally applicable.

(About the cylindrical member according to the present invention)
The cylindrical member 4 is a cylindrical member made of a metal such as an aluminum alloy material, a general steel material, or a stainless steel material. The cylindrical member 4 incorporates a bearing and the like. When the cylindrical member 4 is inserted into the elastic roller 1 by a certain amount and the elastic roller 1 is rotated, the cylindrical member 4 is centered on its axis without slipping. Thus, it is configured so that it can be easily rotated. When the elastic roller 1 is used as a toner supply roller or the like, the outer diameter of the cylindrical member 4 is normally selected to be the same as the member to be pressure-bonded when incorporated into the cartridge, but is not particularly limited. In many cases, it is determined by the specifications of the image forming apparatus to be incorporated. In the measurement of uneven circumferential hardness in the present invention, for example, the outer diameter may be 16 mm and the length may be 50 mm. The outer diameter of the cylindrical member 4 may be an arbitrary outer diameter, and is preferably substantially equal to a member that actually enters and contacts the elastic roller 1. Usually, it is 10 mm-20 mm, Preferably it is 12 mm-18 mm. The axial length of the cylindrical member 4 may be selected according to the number of measurement points and the measurement area, and is usually 10 to 320 mm, preferably 20 to 100 mm.

(About the elastic roller according to the present invention)
Examples of the elastic material forming the elastic layer 3 of the elastic roller 1 according to the present invention include polyurethane, nitrile rubber, ethylene propylene rubber, ethylene propylene diene rubber, styrene butadiene rubber, butadiene rubber, isoprene rubber, and natural rubber. , Rubber raw materials such as silicone rubber, acrylic rubber, chloroprene rubber, butyl rubber, epichlorohydrin rubber, or monomers that are raw materials for producing these rubber raw materials (these monomers may also be referred to as rubber raw materials) What is necessary is just to select and use what can have the target characteristic from the elastic body obtained by using. It may be an elastic body obtained by using the rubber raw material alone or a rubber raw material combining two or more of these rubber raw materials.

  The elastic layer 3 is preferably a foamed elastic layer. A foamed elastic body roller having a foamed elastic body layer is often used by being pressure-bonded to another member, and the contact / intrusion pressure on the other member affects the image. Further, generally, the foamed elastic layer is more likely to have a circumferential variation due to the foamed state, and the hardness unevenness around the circumference is larger, so this hardness measurement method can be suitably used.

  Among the materials of the foamed elastic layer, polyurethane foam that forms a low-hardness elastic layer is preferable. There is no restriction | limiting in particular as a urethane raw material (rubber raw material) for forming a polyurethane foam, From the conventionally well-known urethane raw material, it can select suitably and can be used.

(About the elastic roller manufacturing method according to the present invention)
The manufacturing method of the elastic roller according to the present invention is not particularly limited, and a suitable method may be selected from known manufacturing methods. Specifically, the elastic body layer 3 is formed by covering the cored bar 2 made of a metal material such as iron or stainless steel and having a diameter of 4 to 10 mm and a length of 200 to 400 mm with a foamed elastic body. Can be manufactured. The outer diameter of the elastic body roller 1 is not particularly limited, and may have various outer diameters depending on the purpose. In general, the outer diameter may be 10 to 20 mm.

  In the method for measuring the hardness of an elastic roller according to the present invention, the pretreatment conditions and measurement atmosphere of the elastic roller 1 as a measurement object may be appropriately determined according to the purpose of the hardness measurement. For example, under low temperature / low humidity or high temperature / high humidity. Usually, the measurement is performed after performing a process in which the elastic roller 1 as a measurement object is conditioned in the measurement environment for a certain time, for example, 1 hour or more.

  The elastic roller evaluation method according to the present invention is to evaluate an elastic roller using the hardness measurement method, and when the elastic roller is used as a member of an image forming apparatus such as a toner supply roller, unevenness occurs. It is suitable for determining whether or not a good image with no image can be obtained. Normally, when there is uneven circumferential hardness on the elastic roller, the elastic roller does not uniformly contact a member that enters and abuts on the elastic roller, resulting in unevenness in the obtained image. In the method according to the present invention, the hardness is measured in consideration of the outer diameter blur of the elastic roller while rotating the elastic roller with a constant shaft interval, as in the actual use of the elastic roller, so that the accuracy is more accurate. Well, it is possible to measure circumferential hardness unevenness in line with actual use. Therefore, there is a good correlation between the obtained measurement value of the circumferential hardness unevenness and the image evaluation result, and the elastic roller is suitable as a member of the image forming apparatus without incorporating the elastic roller into the image forming apparatus. It can be easily determined from the measured value. The hardness measuring method according to the present invention is not limited to the measurement of the elastic roller used for the member of the image forming apparatus, and it goes without saying that it can be used when measuring the hardness of a general elastic roller.

  EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated concretely, this invention is not limited to these.

  The polyol component (polyol, foam stabilizer, catalyst, foaming agent) and polyisocyanate component having the composition shown in Table 1 were adjusted to a liquid temperature of 25 ° C. And both components were mix | blended with predetermined amount, and it stirred for 5 second with the stirrer. This was poured into a cavity of a molding die for an elastic roller, which was preliminarily adjusted to 40 ° C., in which a core metal 2 made of SUS304 and having a diameter of 5 mm and a length of 270 mm was attached at a predetermined position inside, and an electric furnace at 100 ° C. Cured for 20 minutes. Then, it took out from the metal mold | die and produced the elastic body roller 1 whose outer diameter is 16 mm. Further, for these elastic rollers 1, circumferential hardness unevenness was measured and image evaluation was performed.

  Roller No. In No. 1, the metal mold 2 was set up and cured so that the metal core 2 disposed on the metal mold was vertical. Roller No. In Nos. 2 and 3, the metal mold 2 placed on the metal mold 2 was turned sideways so as to be parallel to the electric furnace floor surface and cured. As a result, the roller No. 1, 2 and 3 were obtained. Also, roller No. No. 4 was obtained by adjusting the position of the core metal so that the outer diameter deflection was 0.2 mm, and molding and curing. The obtained elastic roller 1 was pretreated by being left to stand in an atmosphere of 25 ° C. and 50% RH for 1 hour.

1) Trade name, polyether polyol manufactured by Sanyo Chemical Co., Ltd., OH value = 23
2) Trade name, Toray Dow Corning Co., Ltd. silicone foam stabilizer 3) 4) Trade name, Tosoh Co., Ltd. tertiary amine catalyst 5) Trade name, Mitsui Chemicals Polyurethane Co., Ltd. isocyanate, NCO % = 48
6) Product name, isocyanate manufactured by Mitsui Chemicals Polyurethanes Co., Ltd., NCO% = 31.

[Example 1]
In the measurement method of the present invention, the pre-processed elastic roller was attached to the elastic roller rotating mechanism of the hardness measuring device 6. In this embodiment, three hardness measuring devices 6 are connected, and the penetration rate of the cylindrical member 4 with respect to the elastic body roller 1 is adjusted to be 85%. The rotatable cylindrical member 4 has an outer diameter of 16 mm and an axial length of 50 mm, and simultaneously measures the hardness of the elastic layer 3 at three locations in the axial direction of the elastic roller 1 while rotating the elastic roller 1 at 15 rpm. The measurement data was recorded at 30 Hz.

3 having a width of 50 mm at the center of the portion covered with the elastic body layer 3 and a width of 50 mm located at 10 mm to 60 mm from both ends of the elastic body layer 3 coating (may be referred to as an image left portion and an image right portion) The location was used as a location for measuring hardness. From the hardness measurement data of the elastic body roller, M1 is the maximum hardness value for one revolution of the elastic roller 1, M2 is the minimum hardness value for the one circumference, and A is the average hardness value for the one circumference. Based on the following formula (1), circumferential hardness unevenness B at each location was determined. The results are shown in Table 2.
B = 100 × (M1-M2) / A (1).

[Comparative Example 1]
In Comparative Example 1, as a conventional hardness measurement method, a hardness measuring instrument equipped with a plate-like jig 9 having a width of 10 mm, a length of 50 mm, and a height of 10 mm as shown in FIGS. It was measured. When the elastic layer 3 was pressed by the plate-shaped jig 9 at a speed of 10 mm / min, the load (g) required to deform 1 mm was measured and used as the conventional hardness. The conventional hardness was measured at 4 points in the circumference and 3 points in the axial direction, and the maximum value m1 of the hardness at the 4 points of circumference, the minimum value m2 at the 4 points of circumference, and the average a of the 4 points of the circumference, Based on 2), the conventional circumferential hardness unevenness b at each location was determined. The results are shown in Table 3.
b = 100 * (m1-m2) / a ... (2).

[Image evaluation method]
Image evaluation was carried out by changing the toner supply roller of the cartridge (magenta) for the laser beam printer to the rollers 1 to 4 described above. The laser beam printer used was “HP Color LaserJet 3600” (trade name) manufactured by Hewlett-Packard Company, which was used in an environment of a temperature of 15 ° C. and a humidity of 10%.

Evaluation of density uniformity in image evaluation was performed according to the following criteria.
◯: A uniform image can be obtained Δ: Slight density appears in the period of the toner supply roller X: Gray level appears in the period of the toner supply roller

  As is apparent from the results in Table 2, a roller No. having a circumferential hardness unevenness B of 9% or less obtained by the measurement method of the present invention according to Example 1 was used. In No. 1, the image was uniform and the image evaluation was good. Roller No. When the ratio was 13% or less of 2, an image evaluation Δ was obtained, with a slight shading appearing on the left side of the image in the period of the toner supply roller. Roller No. When 3% and 4% were 16% or more, shading appeared in the period of the toner supply roller, and the evaluation was x. As described above, the image evaluation and the circumferential hardness unevenness B showed good coincidence. That is, in the measurement in the present example, when the circumferential hardness unevenness B was less than 10%, the uniformity of density in image evaluation was a good result.

  On the other hand, as is clear from the results in Table 3, the roller No. 3 in which the circumferential hardness unevenness b in the conventional measuring method according to Comparative Example 1 is 3% or less is all used. In the case of No. 1, the image evaluation was good. 4 was an image evaluation x. That is, the image evaluation and the circumferential hardness unevenness b did not match. Further, in the rollers 2 and 3, all the circumferential hardness unevenness b was 8% or less, but the image evaluation was divided into Δ and x, and similarly, the image evaluation and the circumferential hardness unevenness b did not match.

  Normally, since the density of the image is generated due to the presence of circumferential hardness unevenness, the density uniformity of the image should be good if the circumferential hardness unevenness is small, but it is sufficient between the conventional circumferential hardness unevenness b and the image evaluation. There was no coincidence. In the conventional measurement method, since the consistency between the image evaluation and the circumferential hardness unevenness b is low as a whole, there are some which have good consistency, but the overall consistency is x.

[Examples 2 to 5]
Roller No. with density uniformity of x level in image evaluation. No. 4, ○ level roller No. 1 was attached to the elastic roller rotating mechanism of the hardness measuring device 6 as in Example 1 after the pretreatment. The circumferential hardness unevenness B was measured in the same manner as in Example 1 except that the penetration rate of the cylindrical member 4 with respect to the elastic roller 1 was changed to the values shown in Table 4, and image evaluation was performed.

  In Examples 2 to 5, the image evaluation result and the circumferential hardness unevenness B showed good agreement. In particular, in Examples 3 and 4, the difference between the image evaluation ○ and the circumferential hardness unevenness B of the x level was large.

DESCRIPTION OF SYMBOLS 1 Elastic body roller 2 Core metal 3 Elastic body layer 4 Rotating cylindrical member (cylindrical member)
5 Load cell 6 Hardness measuring instrument 7 Cable 8 Jig 9 Plate-like jig A Axial distance R2 between the shaft of the cylindrical member and the shaft of the elastic roller The elastic roller between the two shafts when the cylindrical member enters the elastic layer Radius of

Claims (6)

In the hardness measurement method of the elastic body roller provided with the elastic body layer on the outer periphery of the core metal,
A step of making the axis of the rotatable cylindrical member parallel to the axis of the elastic roller;
Intruding the cylindrical member into the elastic layer so that the elastic layer is deformed by the cylindrical member while maintaining the parallelness of the two axes;
A step of rotating the cylindrical member passively with respect to the rotating elastic roller while rotating the elastic roller with a constant axial distance between the cylindrical member and the elastic roller;
A step of measuring hardness by electrically converting a load applied to the cylindrical member;
A method for measuring the hardness of an elastic roller, comprising:   2. The method for measuring the hardness of an elastic roller according to claim 1, wherein the elastic layer is a foamed elastic layer. In the step of allowing the cylindrical member to enter the elastic layer,
When the average radius of the elastic roller before the hardness measurement is 100%, the radial distance of the elastic roller after the cylindrical member enters is 65% or more and 95% or less of the average radius of the elastic roller. The method for measuring the hardness of the elastic roller according to claim 1, wherein a distance between two axes of the cylindrical member and the elastic roller is set. The means for measuring the hardness by electrically converting the load applied to the cylindrical member continuously converts the pressure when the cylindrical member is inserted into the elastic roller into an electric signal through the load cell and measures it. Means,
4. A method for measuring the hardness of an elastic roller according to claim 1, wherein the load is measured at least at eight or more locations in the circumferential direction of the outer periphery of the elastic roller.   The hardness measurement method for an elastic roller according to any one of claims 1 to 4, wherein the hardness is measured at three or more locations in the axial direction of the elastic roller.   An evaluation method for an elastic roller, wherein the elastic roller used in the image forming apparatus is evaluated using the hardness measurement method according to claim 1.

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