JP5837814B2 - Roller manufacturing mold cap, roller manufacturing mold and roller manufacturing method - Google Patents

Description

  The present invention relates to a roller manufacturing die cap, a roller manufacturing die, and a method of manufacturing a roller. In particular, the present invention relates to a roller manufacturing die cap, a roller manufacturing die, and a roller manufacturing method capable of sufficiently suppressing the occurrence of burrs on the end face of the central portion of the core metal.

  In an electrophotographic image forming apparatus such as a copying machine, a facsimile, or a laser beam, as a developing roller, a charging roller, a toner supply roller, a transfer roller, a cleaning roller, a paper feeding roller, a pressure roller for fixing, a roll shape The conductive elastic member, that is, a conductive roller is frequently used.

  These rollers generally have a structure in which an elastic layer made of a rubber material or a resin material is supported on the outer periphery of a resin or metal shaft (core metal), and in particular, the elastic layer has a low hardness. Many rollers made of polymer elastic foam are used. Among them, the most commonly used is a polyurethane foam roller having an elastic layer formed of polyurethane foam.

  A general manufacturing method of such a roller will be described with reference to FIG. As shown in FIG. 6 (A), a roller mold 62 is fitted into a cylindrical mold body 60 and both ends thereof, and both ends of the mold body 60 are closed and the core metal 63 is held. And a cap 50 to be used. In this state, the raw material 68 is poured into the mold and cured, and the core metal 64 and the elastic layer 69 are integrally formed as shown in FIG. 6 (B). The mold is removed from the molding roller member 70 thus obtained (FIG. 6C), both ends of the elastic layer 69 are cut (FIG. 6D), and the finished roller 72 is moved. Is obtained (FIG. 6E).

  Patent Document 1 describes a roller manufacturing die including a cap having a fitting opening for inserting and supporting a cored bar from an end thereof to at least a cutting position of an end of an elastic layer. An example of the cap of Patent Document 1 is shown in FIG. 5. The cap 50 includes a cap main body 52 that closes an end of the mold main body, and a projecting portion (fit inlet) 54 that holds a cored bar 64 on the inner periphery 56. Have. As shown in FIG. 6B, the raw material 68 is introduced into the outer periphery 58 of the protrusion 54. In Patent Document 1, as shown in FIG. 6D, the elastic body layer 69 is cut at a portion floating from the core metal 63 due to the protruding portion 54, so that the core metal 63 is not damaged. It describes that cutting is easy. In the cap described in Patent Document 1, as shown in FIG. 5, the thickness of the protrusion is constant from the end on the cap body 52 side to the tip of the protrusion, and the protrusion has a straight cross-sectional shape. Here, in Patent Document 1, the metal core has a shape having a constant outer diameter from the central portion to the end portion, but in FIG. 6, the outer diameters are smaller at both end portions 66A and 66B than the central portion 64, and therefore the central portion. An end drawing type cored bar 63 having end faces 67 at both ends is shown.

  Further, in Patent Document 2, when a cap holds an end drawing type cored bar as shown in FIG. 6, an end portion (reference numeral 65 </ b> A in FIG. 6A) and an end face (FIG. 6A). A state in which the reference numeral 67) in (E) is covered with a cap is shown in FIG.

JP 2005-224946 A JP 2006-264143 A

  However, according to the study of the present inventor, when a roller is manufactured as shown in FIG. 6 using the cap 50 shown in FIG. 5, as shown in FIG. Although it is in contact with the end surface 67 of the core metal central portion 64, it has been found that the resin may penetrate between them and the elastic body layer may be formed up to the end surface 67 of the core metal central portion 64. Generally, when a roller having such an end-drawing type cored bar is mounted on an image forming apparatus, the cored bar ends 66A and 66B are attached to the apparatus and fixed to the apparatus at an end surface 67 at the center part of the cored bar. . Therefore, if burrs are generated on the end surface 67 at the central portion of the core bar in this way, when the roller is mounted on the image forming apparatus and rotated, the roller is laterally displaced, leading to deterioration in image quality. Further, even if the burrs on the end face 67 are cleaned after the elastic layer is formed, the number of manufacturing steps increases, and additional equipment such as a cleaning device is required, resulting in high costs.

  Further, in Patent Document 2, it is illustrated that the raw material is injected in a state where the end portion of the central part of the core metal is covered with the cap, and the elastic body layer is formed. No consideration is given to preventing the occurrence of burrs on the end face of the gold central part.

  Therefore, the inventors further studied and found that merely covering the end portion of the central portion of the core metal with the cap does not necessarily sufficiently suppress the occurrence of burrs on the end surface of the central portion of the core metal. That is, even if the end of the central part of the core metal is covered with the cap, if the contact pressure between the end of the central part of the core metal and the cap is not sufficient, the resin will still soak into the end surface and burrs will occur. is there.

  Therefore, in view of the above problems, the present invention provides a roller manufacturing die cap, a roller manufacturing die, and a roller manufacturing method capable of sufficiently suppressing the occurrence of burrs at the end surface of the central portion of the core metal. With the goal.

  As a result of intensive studies by the inventor to achieve the above-described object, the inner diameter of the protruding portion of the cap covering the end of the central portion of the core metal and the outer diameter of the central portion of the core metal are designed to satisfy a predetermined relationship. Then, when the contact pressure between the end of the central portion of the core metal and the cap when the core metal is held by the cap is appropriately secured, it has been found that the above object can be achieved and the present invention has been completed. It was.

That is, in view of the above problems, the gist of the present invention is as follows.
The die cap for manufacturing a roller of the present invention is used in a die for producing a roller having a cored bar and an elastic body layer disposed on the outer periphery of the cored bar, and the cored bar is disposed inside the cored cap. A cap provided at the end of a cylindrical mold body for
A cap body that closes an end of the mold body;
A substantially cylindrical protrusion that extends from the cap body, holds the cored bar on the inner periphery, and is introduced with the raw material of the elastic layer on at least a part of the outer periphery;
The projecting portion has a first portion having a first inner diameter R1 that holds the end portion of the core metal having a smaller diameter than the central portion of the core metal, and a first portion that is larger than the first inner diameter R1 that covers the end portion of the central portion of the core metal. A second portion having two inner diameters R2,
And the outer diameter R of the central portion of the core metal, the smaller the second inner diameter R2 than the outer diameter R of the central portion of the metal core, the difference (R-R2), Ri der least 0.15 mm,
The difference (R′−R1) between the outer diameter R ′ of the cored bar end and the first inner diameter R1 smaller than the outer diameter R ′ of the cored bar is 0.08 mm or more and 0.12 mm or less. Oh, wherein the Rukoto.

  Further, (R-R2) is preferably 0.21 mm or less, and it is more preferable that the outer peripheral diameter R3 of the protrusion gradually decreases from the cap body side toward the protrusion tip.

The mold for producing a roller of the present invention is a mold for producing a roller having a cored bar and an elastic layer disposed on the outer periphery of the cored bar,
A cylindrical mold body for arranging the cored bar inside;
A cap body that closes an end of the mold body, and a substantially cylindrical shape that extends from the cap body, holds the cored bar on the inner periphery, and introduces the raw material of the elastic layer into at least a part of the outer periphery A cap having a protrusion, and
The projecting portion has a first portion having a first inner diameter for holding a core metal end having a smaller diameter than the central portion of the core metal, and a second inner diameter larger than a first inner diameter covering the end portion of the central portion of the core metal. A second part having
And the outer diameter R of the central portion of the core metal, the smaller the second inner diameter R2 than the outer diameter R of the central portion of the metal core, the difference (R-R2), Ri der least 0.15 mm,
The difference (R′−R1) between the outer diameter R ′ of the cored bar end and the first inner diameter R1 smaller than the outer diameter R ′ of the cored bar is 0.08 mm or more and 0.12 mm or less. Oh, wherein the Rukoto.

  Further, (R-R2) is preferably 0.21 mm or less, and it is more preferable that the outer peripheral diameter R3 of the protrusion gradually decreases from the cap body side toward the protrusion tip.

The method for manufacturing a roller according to the present invention is a method for manufacturing a roller having a central part, a cored bar having a cored bar end smaller in diameter than the central part, and an elastic body layer disposed on the outer periphery of the central part of the cored bar. Because
Introducing the raw material of the elastic layer in a state where the cored bar is disposed in the mold body of the roller manufacturing mold;
Forming the elastic layer in the mold in a state where the cap of the mold is arranged, and obtaining a molding roller member;
The molding roller member is taken out from the mold, and both ends of the elastic layer are cut so that the end face of the boundary between the core metal end and the central portion of the core metal is exposed, and the finished roller is Obtaining a step;
It is characterized by having.

  According to the present invention, the inner diameter of the protruding portion of the cap covering the end portion of the central portion of the core metal and the outer diameter of the central portion of the core metal are designed to satisfy a predetermined relationship. It has become possible to sufficiently suppress the generation of burrs.

It is sectional drawing in the separation state of the cap 10 used for the metal mold | die for roller manufacture according to this invention, and a part of core metal 42 hold | maintained at this cap. It is sectional drawing in the state which hold | maintained the metal core 42 of the metal mold | die 30 for roller manufacture according to this invention. (A)-(F) are sectional drawings explaining each process of the manufacturing method of the roller according to this invention. In an Example and a comparative example, it is a graph which shows the relationship between the difference (R-R2) of the outer diameter R of the center part of a metal core, and the 2nd inner diameter R2 of a cap, a Paris incidence, and runout accuracy. It is sectional drawing of the conventional cap 50 used for the metal mold | die for roller manufacture. (A)-(E) are sectional drawings explaining each process of the manufacturing method of the conventional roller.

  Hereinafter, the present invention will be described in more detail by describing embodiments of the present invention with reference to the drawings.

  FIG. 2 shows a roller manufacturing die (hereinafter simply referred to as “die”) 30 according to an embodiment of the present invention. Moreover, the cap 10 used for this metal mold | die 30 concerning one Embodiment of this invention is shown in FIG. The metal mold 30 is a metal mold for manufacturing a roller 40 (FIG. 3 to be described later) having a metal core 42 and an elastic body layer 46 disposed on the outer periphery of the metal core 42. The mold 30 includes a cylindrical mold body 28 and caps 10 that are fitted and inserted at both ends thereof, close both end portions 28 </ b> A of the mold body 28, and hold the core metal 42. Here, “the cap closes both ends of the mold body” does not mean that both ends are completely closed by the cap, but for injecting the raw material of the elastic layer as described later. It is allowed to provide a groove. The mold body 28 is for placing the cored bar 42 inside. As shown in FIG. 1, the cap 10 has a cap body 12 and a substantially cylindrical protrusion 14. The cap body 12 has a function of closing the end 28 </ b> A of the mold body 28. The projecting portion 14 extends from the cap body 12, holds the core metal 42 on the inner periphery 16, and introduces the raw material 45 of the elastic body layer 46 into at least a part of the outer periphery 18.

  The protrusion 14 has a first part 20 having a first inner diameter R1 and a second part 22 having a second inner diameter R2 larger than the first inner diameter R1. That is, a step is given to the inner peripheral shape of the protrusion 14. In the first part 20, the cored bar end 44 </ b> A having a smaller diameter than the central part 43 of the cored bar 42 is held. Moreover, in the 2nd site | part 22, as shown in FIG. 2, 43 A of center parts of the metal core 42 are covered.

  The characteristic configuration of the present invention not only simply covers the end portion 43A and the end face 47 of the central portion of the core metal with the protruding portion 14 as described above, but also the outer diameter R of the central portion 43 of the core metal 42 and the second of the cap. The difference (R−R2) from the inner diameter R2 is 0.15 mm or more. Note that the various dimensions of the cap, including the second inner diameter R2, hereinafter refer to the dimensions of the cap 10 alone, in which the cap 10 is not attached to the mold body 28 and the cored bar 42 is not held. . Further, in this specification, the “end portion of the central portion of the core metal” means the outer peripheral portion of the core metal covered with the second portion 22 of the cap 10 in the central portion of the core metal, and “the end surface of the central portion of the core metal” "" Means a stepped portion at the boundary between the cored bar end part and the cored bar central part produced by the cored bar end part having a smaller diameter than the central part.

  In the present invention, by adopting the above configuration, when the cored bar 42 is held by the cap 10 as shown in FIG. 2, the contact pressure between the end 43A of the central part of the cored bar and the second portion 22 of the cap 10 is reduced. It can be secured sufficiently. As a result, it is possible to sufficiently suppress the occurrence of burrs on the end surface 47 of the central portion of the core metal of the roller 40 manufactured by the cap 10 and the mold 30. Therefore, when the roller 40 is mounted on the image forming apparatus and rotated, the roller is not laterally displaced, and the image quality can be ensured. Moreover, it is not necessary to clean the end face 47 of the cored bar central portion 43 after forming the elastic body layer, and the cost is not increased.

  On the other hand, the difference (R−R2) between the outer diameter R of the central portion 43 of the cored bar 42 and the second inner diameter R2 of the cap is preferably 0.21 mm or less. According to the inventor's study, if the contact pressure between the end portion 43A of the core metal central portion and the second portion 22 of the cap 10 is set too high in order to suppress the occurrence of burrs on the end surface 47 of the central metal core portion, Since the first portion 20 and the second portion 22 are deformed, the coaxiality of the cored bar 42 in the state shown in FIGS. 2 and 3A is deteriorated, and as a result, the runout accuracy of the finished product roller is deteriorated. Turned out to be. Therefore, the inventors further examined and found that the coaxiality of the cored bar 42 is not deteriorated if (R-R2) is 0.21 mm or less.

  Therefore, by setting the difference (R−R2) between the outer diameter R of the central portion 43 of the cored bar 42 and the second inner diameter R2 of the cap to be in the range of 0.15 to 0.21 mm, the end surface of the central part of the cored bar It is possible to maintain high roller deflection accuracy while suppressing the occurrence of burrs at 47.

  As in the present embodiment, in the mold 30 and the cap 10, it is preferable that the outer peripheral diameter R3 of the protruding portion 14 gradually decreases from the end portion 24 on the cap body side toward the protruding portion tip 26, as in the present embodiment. In addition, it is more preferable to gradually decrease at a constant rate. According to the inventor's study, when a cap 50 having a straight cross section is used as shown in FIG. 5, the cap 50 is elastic when the cap 50 is removed after the elastic layer is formed as shown in FIG. 6C. It has been found that a part of the body remains adhered to the outer periphery of the protruding portion 54 and that the portion of the elastic layer 68 that is in contact with the protruding portion 54 may break. As shown in FIG. 6D, when the elastic body layer 69 is cut at a portion floating from the core metal 63, the end face of the elastic body layer 69 is also obtained in the finished roller 72 as shown in FIG. May not form cleanly. Therefore, as in the present embodiment, when the protruding portion 14 has a tapered shape that becomes thinner toward the tip, the outer periphery 18 of the protruding portion 14 is easily peeled off from the elastic body layer 46. Therefore, from FIGS. 3B to 3C described later, the elastic layer 46 is less likely to be broken when the cap 10 is removed after forming the elastic layer 46 of the roller, and the roller 40 with a clean end surface of the elastic layer 46 is provided. It can be manufactured.

  In the present embodiment, a preferable case is shown in which the outer peripheral diameter R3 of the projecting portion 14 is continuously decreased from the end portion 24 on the cap body side toward the projecting portion tip 26, that is, always gradually decreasing. However, for example, when the outer peripheral diameter R3 decreases stepwise without increasing once from the end 24 on the cap body side toward the protruding portion tip 26, the outer peripheral diameter R3 gradually decreases. In this case, the effect of suppressing breakage of the elastic layer can be obtained.

  The length (projection height) of the second portion 22 of the projecting portion 14 in the core metal axis direction is preferably 3 to 10% with respect to the width R of the roller center portion. If it is 3% or more, the raw material is more difficult to ooze out to the end face 47 of the core metal central portion 43 when the raw material 45 is injected. Further, if it exceeds 10%, the lateral width of the elastic body layer 46 of the roller cannot be secured sufficiently.

  The length (protrusion height) of the protruding portion 14 in the core metal axis is the first inner diameter R1 of the protruding portion 14 from the viewpoint of forming an appropriate tapered shape in the protruding portion 14 in order to prevent the elastic layer from being broken. It is preferable to be in the range of 75 to 110%, usually about 6 to 9 mm.

  The first inner diameter R1 of the protruding portion 14 is preferably set such that R′−R1 is 0.08 mm or more and 0.12 mm or less in relation to the outer diameter R ′ of the cored bar end portion 44A. This is because this range is the optimum range for maintaining the roller runout accuracy.

  In FIG. 1, the protrusion tip 26 has a shape having a thickness. However, it is also preferable that the tip of the protrusion 14 is not thick and the outer periphery of the tip is a curved surface protruding outward. Thereby, the tip end portion of the protruding portion 14 is more easily peeled off from the elastic body layer 46. Therefore, the elastic body layer 46 is less likely to be broken when the cap 10 is removed after the elastic body layer 46 of the roller is molded, and the roller 40 with a cleaner end face of the elastic layer 46 can be manufactured. Furthermore, the curved surface is preferably a curved surface having a constant radius of curvature, and the radius of curvature is preferably in the range of 0.4 to 0.6 mm.

  The mold body 28 only needs to have an opening at both ends formed in a shape that allows the cap 10 to be attached and detached. The material of the mold body 28 is a metal such as iron, copper, aluminum, stainless steel, ceramics, etc. Can be used. Stainless steel is preferably used from the viewpoint of strength, rust prevention, cost, and the like. The cap 10 can typically be formed by injection molding. The material is not particularly limited as long as it can withstand the heating at the time of molding, but from the viewpoint of releasability of the elastic layer 68 after molding, it is preferable to use polypropylene or the like.

  Next, a method for manufacturing a roller according to an embodiment of the present invention will be described with reference to FIG. The method for manufacturing the roller 40 according to the present embodiment is characterized in that the roller is manufactured using the cap 10 and the mold 30 described above. Specifically, the elastic layer raw material 45 is introduced in a state where the cored bar 42 is disposed in the mold body 28 of the mold 30 (FIG. 3A). At this time, both ends of the mold body 28 are closed by the cap 10 that holds the core end portions 44A and 44B. However, via a communication means inside and outside the mold such as a known groove provided in the cap 10. The raw material 45 is injected. Next, in a state where the cap 10 of the mold 30 is disposed, the elastic body layer 46 is molded in the mold 30 to obtain a molding roller member 48 (FIG. 3B).

  Next, the cap 10 is removed from the molding roller member 48 (FIG. 3C), and the mold body 28 is removed (FIG. 3D), so that the molding roller member 48 is removed from the mold 30. Take out. At this time, the use of the cap 10 sufficiently suppresses the generation of burrs on the end surface 47 in the central portion of the cored bar. Thereafter, a coating layer may be formed by appropriately performing a surface treatment on the elastic layer 46.

  Finally, both end portions of the elastic layer 46 are cut so that the end face 47 at the center portion of the core metal is exposed (FIG. 3E), and the core metal 42 and the elasticity provided on the outer periphery of the core metal 42 are disposed. A finished roller 40 having a body layer 46 is obtained (FIG. 3F). The cutting position may be between the position of the end face 47 at the central portion of the cored bar and the position corresponding to the tip 26 of the protruding portion in FIG. 3 (E). However, as shown in FIG. It is most preferable to cut at a position corresponding to the tip 26 of the portion. As a result, it is possible to more reliably manufacture a roller having no breakage on the end surface of the elastic layer 68.

  In the manufacturing method of the present invention, only the point of manufacturing using the cap 10 and the mold 30 is important, whereby the roller 40 in which the generation of burrs is sufficiently suppressed at the end face 47 of the core metal central part is manufactured. can do. Therefore, the other conditions such as the raw material injection process and the molding process of the elastic body layer can be appropriately set according to a conventional method and are not particularly limited. Further, the material and shape of the core metal 42 of the roller applicable to the present invention and the blending of the raw material 45 are not particularly limited, and a commonly used material can be appropriately used. Examples of the raw material 45 include polyurethane raw materials, and the elastic body layer 46 can be formed of polyurethane. As such a polyurethane raw material, a known polyisocyanate component and polyol component may be used. When imparting conductivity to the roller, an arbitrary conductive agent may be added to the raw material 45.

  The present invention can be applied to any roller used in an electrophotographic image forming apparatus, but can be used particularly for a conductive developing roller.

  In the present embodiment, the cap 10 is provided at both ends of the mold main body 28, and the both ends 43A and 43B of the central portion of the core metal are covered with the cap 10. However, the present invention is not limited to this. In the case where the generation of burrs need only be suppressed on one side of the end surface 47 at the central portion of the core metal, the cap 10 may be disposed only on one side.

  Next, in order to further clarify the effects of the present invention, the following examples and comparative examples are given, but the present invention is not limited to the following examples.

  A mold having a cylindrical mold body having an inner diameter of 20.3 mm and a length of 260 mm and caps according to the following examples and comparative examples was prepared. The cap was manufactured by injection-molding polypropylene so that the shape thereof was as shown in FIG. A combination of a metal mold and a metal core was prepared with the second inner diameter R2 of the second part of the cap and the outer diameter R of the central part of the metal core used corresponding to each cap as the dimensions shown in Table 1 below. . The outer diameter of the cap body was 20.45 mm. Further, the first inner diameter R1 of the first portion of the cap was 5.83 mm, and the outer diameter R ′ of the end portion of the cored bar was 5.94 mm. In addition, the outer peripheral diameter R3 of the protruding portion was 10.7 mm at the cap body side end portion and 9.5 mm at the tip end of the protruding portion. Furthermore, the length of the first part in the core metal axis direction was 8 mm, and the length of the second part in the metal core axis direction was 0.8 mm.

(Manufacture of conductive rollers)
The cored bar was placed in the mold body, and the end of the cored bar was held with the caps of the examples and comparative examples. Next, a polyurethane raw material having a specific gravity of 0.7 and comprising a polyol component system and an isocyanate component system was injected from a groove provided in the cap via an injection head using a high-pressure injector. The polyol component system and the isocyanate component system were impinged and mixed in the injection head at an injection pressure of 300 kg / cm ² and injected into the mold at a supply rate of 7 g / sec in a state of high-pressure foaming. Thereafter, the injected polyurethane foam material was cured to obtain a molded roller member in which a polyurethane foam layer was integrally formed on the outer periphery of the cored bar.

  The cap and mold body were removed from the molding roller member. When it was observed whether the polyurethane foam layer was ruptured when the cap was removed, no rupture occurred. Thereafter, both ends of the elastic layer were cut at a position corresponding to the tip of the protruding portion of the cap to obtain a finished conductive roller.

(Evaluation: Generation of burrs)
Regarding the finished conductive roller, it was visually observed whether burrs were generated on the end face of the central part of the core metal. The burr generation rate for each value of (R−R2) is shown in Table 1 and FIG.

(Evaluation: Roller runout accuracy)
With respect to the finished conductive roller, the runout accuracy of the roller was measured. The results are shown in Table 1 and FIG. The roller was rotated with the cored bar serving as a datum axis, and the value at which the surface at the center of the roller was displaced from a certain reference line was read with a laser, and the runout was measured.

  According to Table 1, in each of the five cases in which (R-R2) is 0.12 and 0.14 on average, one of them has a burr on the end face of the central part of the core metal, and the burr generation rate is 20%. there were. On the other hand, in each of the five examples in which (R-R2) is 0.16, 0.18, 0.20, 0.22 on average, there was no burr on the end face of the central part of the core metal. Therefore, as shown in FIG. 4, when (R-R2) is 0.15 mm or more, it is possible to sufficiently suppress the occurrence of burrs on the end surface of the central portion of the cored bar.

  The roller runout accuracy is preferably 0.030 mm or less according to the runout standard. From Table 1 and FIG. 4, when (R-R2) is 0.21 mm or less, the runout of the roller can surely be 0.030 mm or less, which is preferable.

  ADVANTAGE OF THE INVENTION According to this invention, the metal mold | cap for roller manufacture which can fully suppress generation | occurrence | production of the burr | flash in the end surface of a metal core center part, the metal mold | die for roller manufacture, and the manufacturing method of a roller can be provided.

DESCRIPTION OF SYMBOLS 10 Mold cap for roller production 12 Cap body 14 Protruding part 16 Inner circumference of projecting part 18 Outer part of projecting part 20 First part 22 Second part 24 End part of projecting part on cap body 26 Projecting part tip 28 Mold body 28A End of mold body 30 Roller mold 40 Roller 42 Core 43 Central part of core 43A, 43B End of central part of core 44A, 44B End of core 45 Raw material of elastic layer 46 Elastic body Layer 47 End face of core metal part 48 Forming roller member

Claims (7)

End of a cylindrical mold body used for a mold for manufacturing a roller having a cored bar and an elastic body layer disposed on the outer periphery of the cored bar, and for arranging the cored bar inside A cap provided on the section,
A cap body that closes an end of the mold body;
A substantially cylindrical protrusion that extends from the cap body, holds the cored bar on the inner periphery, and is introduced with the raw material of the elastic layer on at least a part of the outer periphery;
The projecting portion has a first portion having a first inner diameter R1 that holds the end portion of the core metal having a smaller diameter than the central portion of the core metal, and a first portion that is larger than the first inner diameter R1 that covers the end portion of the central portion of the core metal. A second portion having two inner diameters R2,
And the outer diameter R of the central portion of the core metal, the smaller the second inner diameter R2 than the outer diameter R of the central portion of the metal core, the difference (R-R2), Ri der least 0.15 mm,
The difference (R′−R1) between the outer diameter R ′ of the cored bar end and the first inner diameter R1 smaller than the outer diameter R ′ of the cored bar is 0.08 mm or more and 0.12 mm or less. roller manufacturing mold cap, wherein Rukoto Oh.   2. The die cap for manufacturing a roller according to claim 1, wherein a difference (R−R2) between an outer diameter R of a central portion of the core metal and the second inner diameter R <b> 2 is 0.21 mm or less.   3. The roller manufacturing die cap according to claim 1, wherein an outer peripheral diameter R <b> 3 of the protrusion gradually decreases from the cap main body side toward the tip of the protrusion. A mold for producing a roller having a cored bar and an elastic layer disposed on the outer periphery of the cored bar,
A cylindrical mold body for arranging the cored bar inside;
A cap body that closes an end of the mold body, and a substantially cylindrical shape that extends from the cap body, holds the cored bar on the inner periphery, and introduces the raw material of the elastic layer into at least a part of the outer periphery A cap having a protrusion, and
The projecting portion has a first portion having a first inner diameter for holding a core metal end having a smaller diameter than the central portion of the core metal, and a second inner diameter larger than a first inner diameter covering the end portion of the central portion of the core metal. A second part having
And the outer diameter R of the central portion of the core metal, the smaller the second inner diameter R2 than the outer diameter R of the central portion of the metal core, the difference (R-R2), Ri der least 0.15 mm,
The difference (R′−R1) between the outer diameter R ′ of the cored bar end and the first inner diameter R1 smaller than the outer diameter R ′ of the cored bar is 0.08 mm or more and 0.12 mm or less. Oh roller production mold, wherein Rukoto.   The die for roller manufacture according to claim 4, wherein a difference (R-R2) between an outer diameter R of the central portion of the core metal and the second inner diameter R2 is 0.21 mm or less.   6. The roller manufacturing die according to claim 4, wherein an outer peripheral diameter R <b> 3 of the protruding portion gradually decreases from the cap main body side toward the protruding portion front end. A method of manufacturing a roller having a central part and a cored bar having a cored bar end smaller in diameter than the central part, and an elastic body layer disposed on the outer periphery of the central part of the cored,
Introducing the raw material of the elastic body layer in a state where the cored bar is disposed in the mold main body of the roller manufacturing mold according to any one of claims 4 to 6;
Forming the elastic layer in the mold in a state where the cap of the mold is arranged, and obtaining a molding roller member;
The molding roller member is taken out from the mold, and both ends of the elastic layer are cut so that the end face of the boundary between the core metal end and the central portion of the core metal is exposed, and the finished roller is Obtaining a step;
A method for producing a roller, comprising:

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