JP5865062B2 - 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 provides a mold cap for manufacturing a roller that is capable of manufacturing a roller with which the elastic layer is less likely to be broken when the cap is removed after molding of the elastic layer of the roller and the end surface of the elastic layer is clean, and for manufacturing the roller. The present invention relates to a method for manufacturing a mold and a roller.

  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. 5A, 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 64 is held. And a cap 50 to be used. In this state, the raw material 66 is injected into the mold and cured, and the core metal 64 and the elastic layer 68 are integrally formed as shown in FIG. The mold is removed from the molding roller member 70 thus obtained (FIG. 5C), both ends of the elastic layer 68 are cut (FIG. 5D), and the finished roller 72 is moved. Is obtained (FIG. 5E).

  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. 4. The cap 50 includes a cap body 52 that closes an end of the mold body, and a protrusion (insertion opening) 54 that holds the cored bar 64 on the inner periphery 56. Have. As shown in FIG. 5B, the raw material 66 is introduced into the outer periphery 58 of the protrusion 54. And as shown in FIG.5 (D), patent document 1 cuts | disconnects the elastic body layer 68 in the part which floated from the metal core 64 resulting from the protrusion part 54, and does not damage the metal core 64. FIG. It describes that cutting is easy. In the cap described in Patent Document 1, as shown in FIG. 4, 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 section.

JP 2005-224946 A

  However, according to the study of the present inventor, after the elastic body layer is formed, such a cap 50 is removed, and as a result, as shown in FIG. It was found that the portion of the elastic layer 68 that was in contact with the protruding portion 54 might break. As shown in FIG. 5D, when the elastic layer 68 is partially cut off from the cored bar 64, the end surface of the elastic layer 68 is clean even in the finished roller as shown in FIG. 5E. There is a possibility that it cannot be formed.

  Therefore, in view of the above problems, the present invention provides a mold for producing a roller capable of producing a roller in which the elastic layer hardly breaks and the end face of the elastic layer is clean when the cap is removed after molding of the elastic layer of the roller. An object of the present invention is to provide a cap, a roller manufacturing die, and a method for manufacturing the roller.

  When the present inventor diligently studied to achieve the above-described object, when the protrusion of the cap has a straight cross-section, the elastic body may adhere to the protrusion at the time of demolding. The idea is that if the taper shape becomes narrower, the elastic body is less likely to adhere to the projecting portion during demolding. And when this inventor performed roller manufacture after making a prototype of the cap which has such a taper-shaped protrusion part, it discovered that the said objective could be achieved and came to complete this invention.

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 outer diameter of the protrusion gradually decreases from the cap body side toward the protrusion tip ,
The outer peripheral portion of the tip of the protruding portion has a curved surface that protrudes outward,
The outer peripheral diameter of the protrusion is gradually reduced at a constant rate from the cap main body side end to the tip outer periphery .

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 outer diameter of the protrusion gradually decreases from the cap body side toward the protrusion tip ,
The outer peripheral portion of the tip of the protruding portion has a curved surface that protrudes outward,
The outer peripheral diameter of the protrusion is gradually reduced at a constant rate from the cap main body side end to the tip outer periphery .

The method for producing a roller of the present invention is a method for producing a roller having a cored bar and an elastic layer disposed on the outer periphery of the cored bar,
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;
Removing the molding roller member from the mold, cutting both ends of the elastic layer, and obtaining a finished roller;
It is characterized by having.

  According to the present invention, since the outer peripheral diameter of the protruding portion of the cap gradually decreases from the cap body side toward the leading end of the protruding portion, the elastic layer is broken when the cap is removed after the elastic layer of the roller is molded. It has become possible to produce a roller that is less likely to occur and has a clean end face of the elastic layer.

It is sectional drawing of the cap 10 used for the metal mold | die for roller manufacture according to this invention. 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. 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 protruding portion 14 extends from the cap body 12, holds the cored bar 42 at the inner periphery 16, and introduces the raw material 44 of the elastic layer 46 into at least a part of the outer periphery 18.

  The characteristic configuration of the present invention is that, in the mold 30 and the cap 10, the outer peripheral diameter R of the protrusion 14 gradually decreases from the end 20 on the cap body side toward the protrusion 22. With this configuration, the outer periphery 18 of the protrusion 14 is easily peeled off from the elastic layer 46 as compared with the case where the protrusion has a straight cross section as shown in FIG. 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.

  Moreover, it is preferable that the front-end | tip outer peripheral part 24 of the protrusion part 14 makes an outward convex curved surface like this embodiment. Thereby, the outer periphery 18 of the protrusion part 14 becomes easier to peel 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. Here, in the case where the protruding portion 14 has a tapered shape that becomes thinner toward the tip 22, when the cap 10 is manufactured by resin injection molding, the protruding portion tip 22 is thinner than the thick cap body side end 20. The resin has less sink marks. For this reason, the protrusion 22 does not have a sufficiently tapered shape and tends to be in a state close to a straight shape. Therefore, it is preferable that the shape of the tip outer peripheral portion 24 of the protruding portion 14 is designed to be a curved surface in consideration of such resin sink.

  Further, as in the present embodiment, it is more preferable that the outer peripheral diameter R of the protruding portion 14 gradually decreases at a constant rate in a portion 26 between the cap body side end portion 20 and the distal end outer peripheral portion 24. This is because the elastic layer 46 is less likely to break when the cap 10 is removed.

  In this embodiment, it is preferable that the outer peripheral diameter Rmax at the cap body side end 20 of the protrusion 14 is in a range of 160 to 170% of the inner diameter R1 of the protrusion 14. By setting it to 160% or more, the cap body side end 20 of the protrusion 14 can be made sufficiently thick, so that the strength of the protrusion can be sufficiently secured and a tapered shape can be easily formed, and at the time of injection molding This is because sinking occurs greatly, and the effect of making the tip outer peripheral portion 24 of the protruding portion 14 a curved surface can be obtained more significantly. Moreover, it is because the flow path of the raw material 44 of an elastic body layer can fully be ensured by setting it as 170% or less.

  In the present embodiment, the outer peripheral diameter Rmin at the tip 22 of the protruding portion 14 is preferably in the range of 100 to 110% of the inner diameter R1 of the inner diameter R1 of the protruding portion 14, and more preferably 100% of R1. . This is because there is a possibility that the taper shape cannot be sufficiently formed unless the content is 110% or less. As in this embodiment, the tip 22 of the protrusion 14 can be most reliably formed into a tapered shape by making the outer diameter R equal to the inner diameter R1.

  Furthermore, it is preferable that the outer peripheral diameter Rmid of the protruding portion 14 at the boundary portion between the portion 26 gradually decreasing at a constant rate and the distal end outer peripheral portion 24 is in the range of 150 to 160% of the inner diameter R1 of the protruding portion 14. . This is because the strength for holding the cored bar 42 can be sufficiently secured by setting it to 150% or more. By setting it to 160% or less, there is not much sinking at the boundary portion during injection molding. This is because it becomes difficult to form a tapered shape at the outer peripheral portion of the tip, and the effect of making the outer peripheral portion 24 of the tip into a curved surface in consideration of it is more prominent.

  In the present embodiment, the inner periphery 16 of the protrusion 14 that holds the core metal 42 is configured to protrude through the inside of the cap body 12 without passing through the root of the protrusion 14. At this time, when the outer diameter of the projecting portion to the inside is R2, the projecting portion 14 at the boundary portion between the portion 26 gradually decreasing at a constant rate and the distal end outer peripheral portion 24 as shown by a broken line in FIG. It is preferable that the outer peripheral diameter Rmid is equal to R2. In general, R2 is in the range of 150 to 160% of R1.

  It is preferable that the front-end | tip outer peripheral part 24 is a curved surface which has a fixed curvature radius, and it is preferable that this curvature radius shall be in the range of 0.4-0.6 mm. When the thickness is 0.4 mm or more, taking into account the resin sink, the elastic layer 46 is less likely to break when the cap 10 is removed, and when the thickness is 0.6 mm or less, it gradually decreases at a constant rate. This is because the boundary between the portion 26 and the tip outer peripheral portion 24 can be smoothly connected.

  The length (protrusion height) of the protruding portion 14 in the core metal axis is 75 to 75 of the 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 within a range of 110%, usually about 6 to 9 mm.

  In the present embodiment, the outer peripheral diameter R of the projecting portion 14 has been shown to be preferably continuously reduced from the end 20 on the cap body side toward the projecting portion tip 22, that is, always gradually reduced. Is not limited to this. For example, if the outer peripheral diameter R is gradually reduced, such as when the outer peripheral diameter R decreases stepwise without increasing once from the end 20 on the cap body side toward the protrusion tip 22, The effects of the present invention are exhibited.

  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 44 is introduced in a state where the core metal 42 is disposed in the mold body 28 of the mold 30 (FIG. 3A). At this time, both ends of the mold main body 28 are closed by the cap 10 that holds the cored bar 42, but the raw material 44 is connected via a communication means inside and outside the mold such as a known groove provided in the cap 10. Make an injection. 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 main body 28 is further removed (FIG. 3D), thereby removing the molding roller member from the mold 30. . When the cap 10 is removed from the mold, the outer peripheral diameter R of the protrusion 14 of the cap 10 gradually decreases from the end 20 on the cap body side toward the protrusion tip 22, so that the outer periphery 18 of the protrusion 14 is an elastic layer. Since it becomes easy to peel from 46, it becomes difficult to produce a fracture | rupture in the elastic body layer 46. FIG. Thereafter, a coating layer may be formed by appropriately performing a surface treatment on the elastic layer 46.

  Finally, both ends of the elastic body layer 46 are cut (FIG. 3E), and a finished product roller 40 having a cored bar 42 and an elastic layer 46 disposed on the outer periphery of the cored bar 42 is provided. Is obtained (FIG. 3F). At this time, in FIG. 3E, the elastic body layer 46 is cut at a position where it floats from the cored bar 42 due to the protruding portion 14 of the cap. Thereby, it can cut | disconnect easily, without damaging the metal core 42. FIG.

  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 with a clean end surface of the elastic layer 46 can be manufactured. 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 44 are not particularly limited, and a commonly used material can be appropriately used. However, the present invention is effective when the elastic layer 46 is formed of polyurethane using a raw material that easily causes the elastic layer to adhere to the outer periphery of the protruding portion of the cap when the conventional method is used, for example, a polyurethane raw material. It is. As such a polyurethane raw material, a known polyisocyanate component and polyol component may be used. In order to impart conductivity to the roller, any conductive agent may be added to the raw material 44.

  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.

  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.

Example 1
By injection-molding polypropylene, as shown in FIG. 1, the outer peripheral diameter R of the protrusion gradually decreases from the end of the cap body at a constant rate, and the outer periphery of the tip has a cap shape that has a convex curved surface outward. Manufactured. Here, the outer diameter of the cap body was 20.45 mm, and the dimensions of each part were as shown below.
Outer diameter Rmax at the end of the cap on the cap body side: 11 mm
Outer diameter Rmin at the tip of the protrusion: 5.94 mm
Protrusion outer diameter Rmid: 9.5 mm
Protrusion inner diameter R1: 5.94 mm
The outer diameter R2 of the protruding part into the cap body: 9.5 mm
Curvature radius of tip outer periphery: 0.5mm
Length of projecting portion in the core metal axis direction: 8mm
Cap body core length: 20mm

( Reference example )
A cap having the same shape and dimensions as in Example 1 was manufactured, except that the outer peripheral portion at the tip of the protruding portion was not curved and only the portion had a straight cross-sectional shape. That is, Rmin
Is 9.5 mm (equal to R2) equal to Rmid in Example 1.

(Comparative example)
As shown in FIG. 4, a cap having a projecting portion having a straight cross-section was manufactured. The outer diameter R ′ of the protrusion is constant 9.5 mm from the end of the protrusion on the cap body side to the tip. Other dimensions are the same as in Example 1 and the reference example .

(Manufacture of conductive roller and evaluation of breakage)
A core metal having an outer diameter of 5.94 mm at the end and an outer diameter of 8.00 mm at the center is disposed in the mold main body, and the core metal end is held by the caps of Example 1, Reference Example, and Comparative Example. . At this time, as shown to FIG. 5 (A), the end surface of the boundary of the center part of a metal core and an edge part was made to correspond with the protrusion part front-end | tip of a cap. 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. It was observed whether the polyurethane foam layer was ruptured when the cap was removed. Thereafter, both ends of the elastic body layer were cut at a position where the elastic body layer was lifted from the cored bar to obtain a finished conductive roller.

In Example 1, Reference Example, and Comparative Example, 30 conductive rollers were manufactured, and the ratio of those in which the elastic layer was broken at the stage where the cap was removed is shown in Table 1.

As shown in Table 1, in most of the conductive rollers in the comparative example, the elastic layer was ruptured when the cap was removed, whereas in Example 1 and the reference example , rupture did not easily occur. Particularly in Example 1, the breaking rate was zero.

  In the comparative example, for the conductive roller that was broken when the cap was removed, the end surface of the elastic layer in the finished conductive roller was also broken.

  ADVANTAGE OF THE INVENTION According to this invention, the mold cap for roller manufacture which can manufacture the roller which is hard to produce a fracture | rupture in an elastic body layer at the time of cap demolding after shaping | molding of the elastic body layer of a roller, and the end surface of an elastic layer is beautiful, and roller manufacture The manufacturing method of the metal mold | die and 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 End part of projecting part on cap body 22 Protruding part distal end 24 Protruding part distal end outer part 26 Protruding part cap body Parts from the side end to the outer periphery of the tip 28 Mold body 28A End of mold body 30 Roller mold 40 Roller 42 Core metal 42A Core metal edge 44 Elastic layer raw material 46 Elastic body layer 48 Molding Roller member

Claims (3)

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 outer diameter of the protrusion gradually decreases from the cap body side toward the protrusion tip ,
The outer peripheral portion of the tip of the protruding portion has a curved surface that protrudes outward,
A roller cap mold cap , wherein the outer peripheral diameter of the protruding portion gradually decreases at a constant rate from the cap main body side end portion to the tip outer peripheral portion . 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 outer diameter of the protrusion gradually decreases from the cap body side toward the protrusion tip ,
The outer peripheral portion of the tip of the protruding portion has a curved surface that protrudes outward,
The roller manufacturing die , wherein the outer peripheral diameter of the protrusion gradually decreases at a constant rate from the cap main body side end to the tip outer peripheral portion . A method of manufacturing a roller having a cored bar and an elastic layer disposed on the outer periphery of the cored bar,
Introducing the raw material of the elastic layer in a state where the cored bar is disposed in the mold main body of the roller manufacturing mold according to claim 2 ;
Forming the elastic layer in the mold in a state where the cap of the mold is arranged, and obtaining a molding roller member;
Removing the molding roller member from the mold, cutting both ends of the elastic layer, and obtaining a finished roller;
A method for producing a roller, comprising:

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