JP2010019332A - Manufacturing method and device of foam roller - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method of a foam roller capable of increasing the cell opening area to an area within a specified range by opening closed cells at the peripheral surface of a rubber foam body produced through the molding process of the foam roller and suppressing fluctuation of the opening area. <P>SOLUTION: The manufacturing method for a foam roller includes a foam roller molding process to shape a cylindrical rubber foam body using a die on the periphery of a core metal, and a cell opening process to cast a TEA-CO<SB>2</SB>laser beam onto the rubber foam body peripheral surface of the molded roller so as to at least open the cell surface of the rubber foam body. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a foaming roller manufacturing method and a foaming roller manufacturing apparatus in which a rubber foam is formed on the outer periphery of a metal core. More specifically, the present invention relates to a manufacturing method and manufacturing apparatus for various urethane foam rollers such as a toner supply roller, a developing roller, a charging roller, and a transfer roller, which are appropriately used in an electrophotographic image forming apparatus.

  The rubber foam of the foaming roller includes an open cell body in which cells separated by a partition communicate with each other and a closed cell body in which each cell does not communicate and is independent. Also, there are those in which a skin layer is formed on the outer peripheral surface of the rubber foam and those in which the skin layer is not formed and cells on the outer peripheral surface of the rubber foam are opened. The roller of the image forming apparatus has an open cell body in which the external shape change of the rubber foam due to the temperature change is small, and an outer peripheral cell having a large surface frictional resistance is opened in order to obtain a conveyance force for printing paper and toner. Many having a rubber foam are used.

  As a method for manufacturing a foam roller having an open cell body and having cells on the outer peripheral surface of a rubber foam, a molding method in which the manufacturing process can be shortened relatively easily is used. That is, a rubber raw material is cast into a mold, and foamed and opened in a curing step of the rubber raw material. Here, the open cell body of the rubber foam is formed by a competitive reaction between the curing of the rubber raw material and the bubble formation, and it is necessary to manage the manufacturing conditions precisely in order to obtain a certain stable cell diameter. In addition, the opening of the cell on the surface of the rubber foam is the surface roughness of the mold that comes in contact with the rubber raw material directly through the mold release agent, the rubber raw material and the mold release agent as the molding cycle is repeated. Is strongly affected by mold dirt and the like accumulated on the mold surface. For this reason, there are cases where the number of unopened cells increases, or defects such as unevenness of the opening in which the cell opening area varies depending on the location of the rubber foam, and it is not easy to stably obtain a high-quality foaming roller. .

Thus, a cell opening method on the surface of the foaming roller that solves such defects as opening unevenness has been proposed. For example, there is a method of piercing and punching a jig having a large number of needles on the surface of a rubber foam (see, for example, Patent Document 1). Further, there is a method in which a skin layer on the surface of a flexible polyurethane foam is irradiated with plasma to open a cell (for example, see Patent Document 2). There is also a mold release agent that is coated with a fluororesin (see, for example, Patent Document 3).
JP 2001-114926 A JP 2002-039162 A JP 09-274373 A

  However, the conventional method of piercing the needle described above is a method of mechanically tearing the cell, and the foamed rubber foam can be made open, but the so-called ablation process for selectively removing a part of the foam surface is difficult. It is. Therefore, the cell opening cannot be enlarged to an area within a predetermined range so as to suppress variation in the cell opening area of the rubber foam. In addition, when the temperature of the needle is raised above the melting temperature of the rubber foam and stabbed into the rubber foam, the cell foam expands as the rubber foam in contact with the needle melts or softens. In some cases, the rubber material adheres, and it is possible to stably obtain a certain opening ratio (referred to as the opening ratio of the cell outer peripheral surface of the foam in the rubber foam outer surface area, hereinafter referred to as the opening ratio). difficult.

  The method of opening the cell by irradiating the skin layer of the polyurethane foam with plasma is to continuously irradiate high-energy density plasma ejected from a plasma torch. Control of plasma irradiation is limited to the movement of the workpiece and the plasma torch, and it is difficult to control the plasma irradiation time in the form of fine pulses. Especially when the cell partition of rubber foam is thin, the foam roller surface including the partition melts due to the variation in the thickness of the cell partition, the outer diameter of the foam roller is reduced, the surface is wrinkled, and the cell opening is reversed. If a part is closed, a stable aperture ratio may not be obtained. In addition, when the mold release layer of the mold is coated with a fluorine resin, the rubber material may locally remain in the mold when the number of molding is repeated, which may cause unevenness of the cell opening.

  The present invention relates to a method for producing a foam roller that opens an unopened cell on the outer peripheral surface of a rubber foam produced in the foaming roller molding step, suppresses variation in the opening area, and expands the cell opening to a predetermined area. An object is to provide a manufacturing apparatus.

  The present invention provides a foaming roller manufacturing method and manufacturing apparatus capable of solving such conventional problems.

(1) A method for producing a foam roller according to the present invention includes a foam roller molding step in which a cylindrical rubber foam is molded on the outer periphery of a core metal, and a rubber foam outer peripheral surface of the molded foam roller. A cell opening step of irradiating at least the cell surface of the rubber foam with pulse irradiation of CO ₂ laser light.

(2) Further, the foaming roller manufacturing apparatus according to the present invention shapes the laser beam generated by the TEA-CO ₂ laser oscillator into an irradiation surface shape of the rubber foam outer peripheral surface of the foaming roller, and rubber foaming of the foaming roller. Laser beam irradiating means for guiding laser light to the outer peripheral surface of the body, roller rotating means for gripping the cored bar portion of the foaming roller and rotating about the cored bar of the foaming roller, and the roller rotating means for the foaming roller The roller moving means for moving in the axial direction, the laser light irradiating means, the roller rotating means and the roller moving means are interlocked to sequentially irradiate laser light over the entire outer peripheral surface of the rubber foam of the foam roller. And a control means.

  (3) In addition, the foaming roller manufacturing apparatus according to the present invention limits the irradiation of the laser foam outer peripheral surface between the laser irradiation means and the rubber foam outer peripheral surface of the foaming roller. A plurality of slits having a width of 0.5 to 2.0 times the average cell diameter of the rubber foam, or the average cell diameter of the rubber foam. A plurality of circular holes having a diameter of 0.5 to 2.0 times exist.

  (4) The non-irradiation width between the slits is 0.5 times or more the average cell diameter of the rubber foam, and the non-irradiation width between the circular holes is 0. 0 of the average cell diameter of the rubber foam. It is characterized by being 3 times or more.

  (5) Moreover, the manufacturing method of the foaming roller which concerns on this invention manufactures a foaming roller using the manufacturing apparatus of the foaming roller in any one of said (2) thru | or (4), It is characterized by the above-mentioned.

  (6) Moreover, the foaming roller which concerns on this invention is manufactured by the manufacturing method of the foaming roller as described in said (1) or (5).

According to the present invention, by irradiating the surface of the rubber foam with TEA-CO ₂ laser light, unopened cells on the outer peripheral surface of the rubber foam generated in the molding process of the foaming roller can be opened. Variations can be suppressed and the cell opening can be enlarged to a predetermined area. As a result, it is possible to stably produce a foaming roller having a high surface frictional resistance and excellent transporting force for printing paper and toner.

The foaming roller manufacturing method according to the present invention includes a foaming roller molding step in which a cylindrical rubber foam is molded on the outer periphery of a core metal, and a TEA-CO ₂ laser on the outer peripheral surface of the molded foamed rubber foam. A cell opening step of irradiating light with a pulse to open the cell surface of the rubber foam.

  In the foaming roller molding step, the foamed roller molded product is prepared by a known method. For example, a metal core is supported by mold pieces attached to both ends of a cylindrical cavity of a molding die, and, for example, a foamed urethane rubber raw material mainly composed of polyisocyanate, polyol, water, catalyst, etc. is stirred and mixed with a casting machine. To do. The raw material is poured into a mold cavity and heated for a predetermined time to form a rubber foam around the core metal, and the rubber foam integrated with the core metal is removed from the core metal co-molding mold. To obtain a molded product of a foam roller.

  As the raw material of the rubber foam, various urethane raw materials of so-called flexible urethane foam can be applied. For example, polyester, polyether, polycarbonate and other polyols, and polyisocyanates include diphenylmethane diisocyanate (MDI), tolylene diisocyanate (TDI), naphthalene diisocyanate (NDI), hexamethylene diisocyanate (HDI), isophorone diisocyanate (IPDI). Xylylene diisocyanate (XDI) and the like are used alone or in combination, and are used together with a catalyst, a foaming agent, a foam stabilizer and the like. Examples of the foaming method include a water foaming method using water as a foaming agent, or a mechanical floss method in which fine air is mixed in the raw material.

In the cell opening step, a laser beam generated by a TEA-CO ₂ laser oscillator is used as the laser beam irradiated to the rubber foam outer peripheral surface of the foamed roller molded product.

The laser beam is applied to the rubber foam outer peripheral surface of the foam roller in a pulsed manner. The TEA-CO ₂ laser can irradiate a pulse of 1 μsec, and the irradiation area can be simultaneously irradiated over a relatively wide area, not a spot with a small irradiation area such as a YAG laser.

  The opening of the cell due to laser light irradiation is thought to be due to a minute heat capacity difference between the cell skeleton (cell formation area inside the skin layer) and the cell thin part (skin layer), and the number of irradiation pulses, irradiation interval, irradiation time, etc. By appropriately selecting the irradiation conditions, the cell opening diameter can be homogenized. Further, deformation of the rubber foam can be suppressed and wrinkles generated on the rubber foam surface can be reduced.

  Furthermore, by the irradiation of the laser beam, the cell thin portion on the surface of the rubber foam is ablated, the cell non-opening portion is opened, the opening area of the portion where the cell is opened is enlarged, and the cell opening ratio is increased. For example, as shown in FIG. 2, by applying laser light to the cell opening insufficient portion 41b on the surface of the rubber foam 41, the cell opening ratio is improved like the cell opening sufficient portion 41a, and the cell opening diameter is homogenized. can do.

  The foaming roller manufacturing apparatus shown in FIG. 1 can be used for the cell opening step.

  First, the foaming roller 4 is placed on the roller rotating unit 3 on the roller moving unit 5 and the cored bar portion is supported. Then, the roller rotating unit 3 is activated to rotate the foaming roller 4 in the circumferential direction. . Thereafter, the surface of the foaming roller 4 is irradiated with the laser 1. The laser beam 1 is irradiated by moving the rotating foam roller 4 from one end of the rubber foam in the axial direction to the position of the other end in the axial direction of the rubber foam by the roller moving means 5, thereby The laser beam 1 is sequentially pulsed while scanning.

  The pulse irradiation of the laser beam 1 is performed in conjunction with the laser beam irradiation unit, the roller rotating unit 3 and the roller moving unit 5 by a control unit (not shown). Specifically, the control means may be a known control technique. FIG. 5 is a conceptual diagram of the control means. The integrated controller includes a rotation driver for the rotation means, a movement driver for the movement means, and an irradiation driver for the laser light irradiation means. And electrical signals can be input / output. A rotation motor of a servo motor with an encoder is connected to the rotation driver, a movement motor of a servo motor with an encoder is connected to the movement driver, and a laser oscillator is connected to the irradiation driver. As the integrated controller, a personal computer or a sequencer is used, and by appropriately transmitting a pulse signal to each driver of rotation, movement, and irradiation, the rotation direction, rotation speed, and number of rotations of the rotation unit are changed. By controlling the movement speed and movement amount, the irradiation pulse speed and the number of irradiation pulses of the irradiation means, the rotation of the rubber foam and the movement in the axial direction and the laser irradiation are linked, and the laser is applied to the entire outer peripheral surface of the rubber foam. Irradiate light. Usually, feedback control capable of highly accurate control is used for each means of rotation and movement.

  For the irradiation with the laser beam 1, for example, a laser irradiation apparatus 100 shown in FIG. 4 can be used.

The laser irradiation apparatus 100 of FIG. 4 uses a TEA-CO ₂ (Transversally Excited Atmospheric Pressure-CO ₂ ) laser optical system as laser irradiation means. The direction of the laser beam from the laser oscillator 101 is changed by the reflection mirror 103, the unstable portion of the laser output density at the outer edge of the laser beam is removed by the primary light shielding mask 102, and the rectangular irradiation surface shape is condensed by the cylindrical lens 104. To be shaped. Further, the shaped laser beam 1 is irradiated to the rubber foam outer peripheral surface of the foaming roller 4 directly or via the light shielding mask 2.

  By making the laser light irradiation part and the laser light non-irradiation part adjacent to each other by the light shielding mask 2, the laser non-irradiation part, that is, the non-heating part, restricts deformation of the rubber foam due to the ablation of the laser light irradiation part. Thereby, the wrinkles which generate | occur | produce on the rubber foam surface can be reduced compared with the case where the light shielding mask 2 is not used.

  FIG. 3 shows an example of a light shielding mask 2 that can be used in the present invention. In the present invention, any of the light shielding masks 2a, 2b, 2c, and 2d can be used. Depending on the laser light irradiation conditions such as the rotation speed, movement speed, and laser light pulse irradiation speed of the foam roller, the light shielding mask 2a, It is appropriately selected from 2b, 2c and 2d.

  The light shielding mask 2a has a slit-shaped irradiation window 2a1 that is inclined with respect to the direction of the foaming roller axis. The light shielding mask 2b has a slit-shaped irradiation window 2b1 parallel to the axial direction of the foaming roller. The light shielding mask 2c has a slit-shaped irradiation window 2c1 orthogonal to the direction of the foam roller axis. The light shielding mask 2d has a circular irradiation hole 2d1.

  The slit widths of the irradiation windows 2a1, 2b1, and 2c1 of the light shielding masks 2a, 2b, and 2c are preferably 0.5 times or more and 2 times or less of the average cell diameter of the rubber foam. The diameter of the irradiation window (circular hole) 2d1 of the light shielding mask 2d is preferably 0.5 times or more and 2 times or less the average cell diameter of the rubber foam. When the slit width of the irradiation windows 2a1, 2b1 and 2c1 and the diameter of the irradiation window 2d1 are less than 0.5 times the average cell diameter of the rubber foam, the processing time is extended or the opening of the rubber foam cell is insufficient. There is a case. Conversely, when the slit widths of the irradiation windows 2a1, 2b1 and 2c1 and the diameter of the irradiation window 2d1 exceed twice the average cell diameter of the rubber foam, the surface of the rubber foam may be roughened.

  The non-irradiation width between the slits of the irradiation windows 2a1, 2b1 and 2c1, 0.5 times the average cell diameter of the rubber foam, and the distance between the irradiation parts between the circular holes of the irradiation window 2d1 are the average cell diameter of the rubber foam. If it is 0.3 times or more, the occurrence of wrinkles on the surface of the rubber foam can be suppressed, which is preferable.

  Here, the average cell diameter of the rubber foam is obtained by cutting the rubber foam in a direction perpendicular to the axis, and cutting the maximum diameter of each cell in the vicinity of the outer periphery of the rubber foam. This was calculated by selecting 10 possible cells, measuring the diameter of the cells with an optical microscope, adding the diameters of the cells, and dividing the result by the number of added cells. Further, the cell opening ratio (%) is obtained by measuring and adding the opening lengths of all the cells between 10 mm on the straight line in the axial direction of the rubber foam surface with an optical microscope, and dividing the added value by the measurement range length. It is calculated by multiplying.

  The shape of the laser irradiation window of the light shielding mask is not limited to the shape of the irradiation windows of the light shielding masks 2a, 2b, 2c, and 2d shown in FIG. 3, and it is sufficient that laser light passes, and the processing of the light shielding mask is easy. Not only a round hole and a long hole but an ellipse, a polygon hole, etc. may be sufficient.

  FIG. 4 shows an example in which the light shielding mask 2 is used. However, when the ratio of the thickness of the cell skeleton of the rubber foam to the thin portion of the cell, that is, the heat capacity of the cell skeleton is sufficiently larger than the heat capacity of the thin portion of the cell. Even when the light shielding mask 2 is not provided, since the degree of ablation of the cell skeleton portion relative to the thin cell portion is slight, the cell opening ratio of the rubber foam 41 can be increased.

In FIG. 4, a TEA-CO ₂ laser oscillator capable of performing laser irradiation of a relatively large area at a time by short pulse irradiation is exemplified as the laser irradiation means. However, a laser beam having the same function may be used, and an excimer laser oscillator Is also applicable.

  The foaming roller obtained by the production method according to the present invention can be used for a toner removing / supplying roller, a developing roller, a charging roller, a transfer roller and the like used in an electrophotographic apparatus. The toner removing / supplying roller is a roller that contacts the developing roller and removes old toner remaining on the developing roller by rubbing and simultaneously supplies new toner onto the developing roller.

[Example 1]
Examples of the present invention will be described below, but the present invention is not limited to these examples. “Part” is based on mass.

  As raw materials for the rubber foam of the foaming roller, the following A-based raw materials and B-based raw materials were used.

  As the A-based material, a mixture of the following compounds in advance was used.

90 parts of polyether polyol (trade name: “FA-908”, manufactured by Sanyo Chemical Industries) 10 parts of polymer polyol (trade name: “POP-31-28”, manufactured by Mitsui Takeda Chemical Co., Ltd.) Amine catalyst (trade name: “TOYOCAT-ET”, manufactured by Tosoh Corporation) 0.10 parts Tertiary amine catalyst (trade name: “TOYOCAT-MR”, manufactured by Tosoh Corporation) 0.30 parts Water (foaming) Agent) 2 parts 1 part of silicone foam stabilizer (trade name: “L5366”, manufactured by Nippon Unicar Co., Ltd.).

  In addition, 22 parts of isocyanate (trade name: “Coronate 1025”, manufactured by Nippon Polyurethane Industry Co., Ltd.) was used as the B-based material.

  First, a metal core having electroless nickel plating applied to a steel bar was supported by mold pieces attached to both ends of a cylindrical cavity of a mold. Next, A-type and B-type raw materials were charged into the casting machine, stirred with the mixing head of the casting machine, and cast and cured into the molding die preheated to 60 ° C. Thereafter, the mold was removed, and the end of the roller was cut off to obtain a foamed roller molded product. As a result of examining the foaming state of the rubber foam of the obtained foamed roller molded product, the cell opening diameter distribution and the cell opening ratio were as shown in Table 2.

Thereafter, using the foaming roller manufacturing apparatus shown in FIG. 1 and the TEA-CO ₂ laser irradiation apparatus shown in FIG. 4, the rubber foam surface of the foamed roller molded product was irradiated with laser light. As the TEA-CO ₂ laser irradiation apparatus 100, “IMPACT 2500” (trade name, manufactured by Shinozaki Seisakusho Co., Ltd.) was used. The size of the laser beam at the exit of the laser oscillator 101 was 9 mm long × 8 mm wide, and this was passed through the primary shading mask 102 to cut the size of the laser beam into 8 mm long × 7 mm wide. Further, the size of the laser beam 1 in contact with the surface of the rubber foam with the cylindrical lens 104 is adjusted so as to be condensed to 8 mm in length × 2 mm in width, and the length direction of the laser beam is parallel to the axial direction of the foaming roller 4. It was made to become. The shading mask 2 having an irradiation window range larger than the size of the laser beam 1 is concentric with the center of the axis of the foaming roller 4 as shown in FIG. 4, and the distance to the surface of the rubber foam is 5 mm. Arranged. As the light shielding mask 2, the light shielding mask 2a shown in FIG. The slit width of the irradiation window 2a1 of the light shielding mask 2a was 900 μm, which was 1.5 times the average cell diameter of the rubber foam.

  Under the laser irradiation conditions shown in Table 1, when the surface of the rubber foam was irradiated using the manufacturing apparatus shown in FIG. 1, there was opening unevenness as shown by 41b in FIG. 2 before the laser irradiation. On the other hand, after the laser irradiation, the opening unevenness decreased as shown by 41a. Moreover, as shown in Table 2, both the cell aperture diameter distribution and the cell aperture ratio after laser irradiation were greatly improved. In addition, no change in the outer shape of the foam roller before and after laser irradiation and no occurrence of wrinkles on the surface of the foam roller were observed. The foaming roller obtained in this example showed high performance when used as a toner removal / supply roller.

[Example 2]
The amount of tertiary amine catalyst (trade name: “TOYOCAT-ET”, manufactured by Tosoh Corporation), which is a foaming catalyst for foaming urethane, of the rubber foam raw material of the foaming roller is reduced from 0.10 parts to 0. Molding was performed using the same raw materials and the same conditions as in Example 1 except that the amount was reduced to 0.07 parts. As a result, a foamed roller molded product having a skin layer formed on the surface of the rubber foam was obtained.

  When the molded product of the foaming roller was irradiated with laser light under the same conditions as in Example 1, both the cell opening diameter distribution and the cell opening ratio were greatly improved as shown in Table 2. In addition, no change in the outer shape of the foam roller before and after laser irradiation and no occurrence of wrinkles on the surface of the foam roller were observed. The foaming roller obtained in this example showed high performance when used as a toner removal / supply roller.

[Example 3]
Except for changing the light-shielding mask 2a of Example 1 to the elliptical irradiation windows 2b1 and 2c1 of the other light-shielding masks 2b and 2c, the apparatus and processed product of Example 1 were used, and laser light was applied to the entire surface of the rubber foam. When irradiated, the same effect as in Example 1 was obtained. Further, when the apparatus and processed product of Example 1 were used and the light shielding mask having the same diameter of the irradiation window 2d1 of the light shielding mask 2d as the width of the ellipse was used, the entire surface of the rubber foam was irradiated with the laser beam. The cell opening ratio slightly decreased to 80 (%), but the generation of wrinkles was further improved from that of an ellipse.

It is a perspective view of the laser irradiation state to the rubber foam surface of a foaming roller using the manufacturing apparatus of the foaming roller which concerns on this invention. It is the elements on larger scale which show the foaming state of the rubber foam surface of the foaming roller manufactured by the manufacturing method which concerns on this invention. It is a perspective view which shows the various light shielding masks used for the manufacturing apparatus which concerns on this invention. It is a schematic diagram of a TEA-CO ₂ laser irradiation apparatus used in the production method according to the present invention. It is a conceptual diagram of the control means used for the manufacturing apparatus which concerns on this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Laser beam 2 Shading mask 2a Shading mask 2a1 which has irradiation window inclined with respect to foaming roller axial direction Irradiation window 2b which inclined with respect to foaming roller axial direction Shading mask 2b1 which has irradiation window parallel to foaming roller axial direction Foaming roller axis Irradiation window 2c parallel to the direction Light-shielding mask 2c1 having an irradiation window perpendicular to the foaming roller axial direction Irradiation window 2d perpendicular to the foaming-roller axial direction Light-shielding mask 2d1 having a circular irradiation window 3 Circular irradiation window 3 Roller rotation Means 4 Foam roller 5 Roller moving means 41 Rubber foam 41a Open state before laser irradiation 41b Open state after laser irradiation 42 Core metal 100 Laser irradiation device 101 TEA-CO ₂ laser oscillator 102 Primary light shielding mask 103 Reflective mirror 104 Cylindrical lens

Claims (6)

A foaming roller molding process in which a cylindrical rubber foam is molded on the outer periphery of the core metal;
A cell opening step of irradiating the rubber foam outer peripheral surface of the molded foam roller with a pulse of TEA-CO ₂ laser light to open at least the cell surface of the rubber foam;
A method for producing a foam roller, comprising: Laser light irradiation means for shaping the laser light generated by the TEA-CO ₂ laser oscillator into an irradiation surface shape of the rubber foam outer peripheral surface of the foam roller, and guiding the laser light to the rubber foam outer peripheral surface of the foam roller;
Roller rotating means for supporting the cored bar portion of the foaming roller and rotating the cored bar of the foaming roller;
Roller moving means for moving the roller rotating means in the axial direction of the foaming roller;
Control means for sequentially irradiating laser light over the entire rubber foam outer peripheral surface of the foaming roller by interlocking the laser light irradiation means, the roller rotating means and the roller moving means;
A foaming roller manufacturing apparatus comprising: Between the laser light irradiation means and the rubber foam outer peripheral surface of the foaming roller, a light shielding mask for limiting the laser light irradiation to the rubber foam outer peripheral surface,
The light shielding mask includes a plurality of slits having a width of 0.5 to 2 times the average cell diameter of the rubber foam, or 0.5 to 2 times the average cell diameter of the rubber foam. The apparatus for producing a foam roller according to claim 2, wherein there are a plurality of circular holes having a diameter less than double. The non-irradiation width between the slits is 0.5 times or more the average cell diameter of the rubber foam,
The apparatus for producing a foam roller according to claim 3, wherein a non-irradiation width between the circular holes is 0.3 times or more an average cell diameter of the rubber foam.   The foaming roller manufacturing method according to claim 1, wherein the foaming roller is manufactured using the foaming roller manufacturing apparatus according to claim 2.   A foam roller manufactured by the method for manufacturing a foam roller according to claim 1.

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