JP2009051072A - Mold - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a mold capable of forming a flat elastic layer even if gas appears on the injection side of a molding material. <P>SOLUTION: The mold is equipped with a cylindrical mold 2, a first edge mold 3 closing one opening of the cylindrical mold 2 and having a sprue 16 through which the molding material flows, a second edge mold 4 closing the other opening of the cylindrical mold 2 and having a vent 36 and an edge mold jig 5 mounted on the first edge mold 3 at the time of thermal molding and characterized in that the housing recess 60 provided to the outside opening 17 of the sprue 16 and the discharge hole extended from the housing recess 60 are provided. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a molding die, and more particularly to a molding die capable of forming a flat elastic layer even when gas appears on the injection side of a molding material.

  A roller 50 having an elastic layer 52 on the outer peripheral surface of a shaft 51 as shown in FIG. 6 is widely used in various fields. For example, printers such as laser printers and video printers, copiers, facsimiles, and complex machines of these types have various images provided with various rollers such as developing rollers, fixing rollers, and conveying rollers according to their functions. A forming apparatus, for example, an image forming apparatus using an electrophotographic method is employed.

  Such a roller 50 is normally manufactured by forming the elastic layer 52 on the outer peripheral surface of the shaft 51 using a molding die. As a molding die used for molding the elastic layer 52, for example, as shown in FIG. 8, a cylindrical die 101 and an injection formed through and attached to one end of the cylindrical die 101 An example is a molding die 100 including a one-end mold 103 having a hole 104 and an other-end mold 102 attached to the other end of the cylindrical mold 101.

  When a molding material is injected into the molding die 100 from the injection hole 104, gas may appear in the injected molding material. Then, when the elastic material is formed by thermoforming the molding material in which the gas appears, bubbles derived from the appeared gas are generated in the elastic layer and / or the elastic layer around the bubble is depressed and formed. Concave portions are generated on the surface and inside of the elastic layer.

  As a means of preventing the appearance of gas during injection of the molding material, the molding material is not directly injected into the injection hole 104, but is once diffused in the circumferential direction before the injection hole 104 and then injected. A method of injecting into the hole 104 is known. For example, as shown in FIG. 9, as a molding die capable of carrying out this method, a cylindrical die 101, an injection hole 104 that is attached to one end portion of the cylindrical die 101 and is formed to penetrate therethrough, and Molding die comprising one end mold 106 having a liquid reservoir 105 defined on the front side of the injection hole 104 and the other end mold 102 attached to the other end of the cylindrical mold 101. (For example, refer to FIG. 1 and FIG. 3 of Patent Document 1).

  However, even when the elastic layer 52 is molded using a molding die having such a liquid reservoir 105, a depressed portion may still be formed in the elastic layer 52 on the one end mold 106 side.

JP 2003-191244 A

  An object of the present invention is to provide a molding die capable of forming a flat elastic layer even when gas appears on the injection side of the molding material.

As means for solving the problems,
According to a first aspect of the present invention, a cylindrical mold, a first end mold having a sprue that closes one opening of the cylindrical mold and through which a molding material flows, and the other end of the cylindrical mold A second end mold that closes the opening and has a vent; and an end mold jig that is attached to the first end mold during heat molding; A molding die having a storage recess continuously provided and a discharge hole extending from the storage recess.

  The molding die according to the present invention includes an end mold jig that is mounted when the elastic layer is molded, and the storage recess and the discharge hole communicate with each other from the outer opening of the sprue when the elastic layer is molded. Even if gas appears near the sprue when the molding material is injected, the gas is discharged to the outside through the housing recess and the discharge hole together with the molding material surrounding it due to thermal expansion of the molding material. Therefore, according to this invention, even if gas appears on the injection side of the molding material, it is possible to provide a molding die that can form a flat elastic layer.

  The molding die according to the present invention is a kind of injection molding die for molding the elastic layer on the outer peripheral surface of the shaft body, and more accurately after the molding material is filled in the cavity of the molding die. Is characterized in that an end mold jig is mounted on the first end mold when the molding material is heat-molded, and the housing recess and the discharge hole are communicated with the outer opening of the sprue. The molding die according to the present invention is suitably used, for example, for manufacturing the roller 50 shown in FIG. The roller 50 includes a shaft body 51 and an elastic layer 52 formed on the outer peripheral surface of the shaft body 51.

  Therefore, the molding die according to the present invention may be any mold in which the housing recess and the discharge hole are sequentially arranged in the outer opening of the sprue during the heat molding, and the storage recess and the discharge hole are formed. The embodiment is not particularly limited. In the present invention, for example, (1) the storage recess and the discharge hole or the first end mold together with the storage recess and the discharge hole are connected to the outer opening of the sprue. A mode in which both of the grooves to be formed are formed in the end mold jig, (2) the first end metal mold together with the housing recess and the groove for forming the discharge hole or the discharge mold together with the end mold jig (3) A storage recess is formed in the end mold jig, and a discharge hole or a groove that forms the discharge hole together with the end mold jig is formed in the first end mold. (4) An aspect in which the housing recess is formed in the end mold jig, and a groove that forms the discharge hole together with the discharge hole or the first end mold is formed in the end mold jig. These modes can be selected as appropriate.

  Hereinafter, the “mode in which the housing recess and the groove that forms the discharge hole together with the first end mold are formed in the end mold jig” of the mode (1) will be described.

  As an example of this aspect (1) in the molding die according to the present invention, for example, as shown in FIG. 1, a cylindrical die 2 into which a shaft body is inserted and one end portion of the shaft body are held. The first end mold 3 having the sprue 16 through which the molding material flows and the other end of the shaft body are held and the cylindrical mold 2 is closed. A second end mold 4 having a vent 36 that closes the other opening, and a storage recess that is attached to the first end mold 3 at the time of thermoforming and is connected to the outer opening of the sprue 16. 60 and an end mold jig 5 having a discharge hole groove (not shown in FIG. 1) extending from the storage recess 60.

  As shown in FIG. 1, the cylindrical mold 2 is a hollow cylindrical body having openings at both ends, and has a uniform outer diameter and inner diameter. When the elastic layer 52 is formed in the cylindrical mold 2, the shaft body 51 is inserted along the axial direction thereof. The cylindrical mold 2 is preferably adjusted to have a surface roughness on its inner surface, and is particularly preferably a mirror surface. The outer diameter, inner diameter, axial length, etc. of the cylindrical mold 2 are adjusted according to the elastic layer 52 to be molded.

  As shown in FIGS. 1 and 2, the first end mold 3 includes a cylindrical end mold body 10 having a holding hole 12 for holding a shaft body 51, and an end mold body 10. It has a disk-shaped flange 11 that projects in the circumferential direction from one end and closes the opening of the cylindrical mold 2, and the flange 11 has a thickness smaller than the depth of the holding hole 12 and its thickness direction. And a sprue 16 penetratingly formed. In other words, the first end mold 3 has a columnar end mold body 10 having a holding hole 12 provided with a flange-shaped flange 11 that closes one opening of the cylindrical mold 2. And the thickness of the collar part 11 is adjusted to be smaller than the depth of the holding hole 12. The first end mold 3 also has a function of determining the contact position of the injection nozzle when the molding material is injected by the end mold body 10.

  As shown in FIGS. 1 and 2, the end mold body 10 is opened at one end thereof, and has a bottomed holding hole 12 for holding a shaft body 51, and a cylindrical body having a shared central axis. It is useful for holding one end of the shaft body 51 and determining the contact position of the injection nozzle. The end mold body 10 is adjusted in the axial length, outer diameter, etc., and the depth, diameter, etc. of the holding hole 12 in accordance with the shaft body 51 to be held. For example, the diameter of the holding hole 12 is adjusted to about 100 to 105% with respect to the outer diameter of the shaft 51 to be held, or the depth of the holding hole 12 is relative to the total length of the shaft 51 to be held. When adjusted to about 3 to 9%, the deviation between the central axis of the shaft body 51 and the central axis of the formed elastic layer 52 is reduced, the outer diameter accuracy of the formed elastic layer 52 is increased, and the elasticity is increased. This is preferable in that the deflection of the layer 52 can be suppressed.

  As shown in FIGS. 1 and 2, the flange portion 11 protrudes in the circumferential direction from one end portion of the end mold body 10 and has a central axis coaxial with the center axis of the end mold body 10. And one opening of the cylindrical mold 2 is closed. The flange portion 11 is adjusted to a thickness smaller than the depth of the holding hole 12. In other words, when the flange 11 is the molding die 1, the outer end surface 14 positioned outside the flange 11 is formed with the flange 11 of the end mold body 10 more than the holding hole bottom surface 13 of the holding hole 12. Located on one end side. When the thickness of the flange portion 11 is adjusted in this way, the axial length of the sprue 16 to be described later is shortened, the remaining amount of the molding material remaining in the sprue 16 is reduced, and the burr formed in the sprue 16 is broken. Can be prevented. Therefore, the thickness of the collar part 11 should just be adjusted as mentioned above, specifically, it is adjusted to about 6 to 25% with respect to the depth of the holding hole 12, and more specifically, It is adjusted to about 1.5 to 2.5 mm. The outer diameter of the flange portion 11 is adjusted to be substantially the same as the opening diameter of the opening in the cylindrical mold 2. As for the collar part 11, the surface roughness of the inner side end surface 15 does not need to be adjusted.

  As shown in FIGS. 1 and 2, the sprue 16 is formed to penetrate in the thickness direction of the flange portion 11 and functions as a passage when the molding material is injected. Since the flange portion 11 has the above thickness, the axial length of the sprue 16 is shortened, the remaining amount of the molding material remaining in the sprue 16 is reduced, and the burrs formed in the sprue 16 are prevented from breaking. Can do. Four sprues 16 are formed at equal intervals on the circumference of a certain distance from the center of the flange portion 11.

  The shape of the vertical cross section (cross section when cut along a plane including the central axis of the flange 11) in the sprue 16 is not particularly limited, and is a substantially rectangular shape extending from the outer end face 14 side to the inner end face 15 side. 1 may be substantially square, but preferably has a trapezoidal shape extending from the outer end face 14 side to the inner end face 15 side, as shown in FIGS. That is, the opening diameter of the inner opening 18 is larger than the opening diameter of the outer opening 17 in the sprue 16. The cross-sectional shape orthogonal to the axis of the sprue 16 may be circular or elliptical. Further, the inner surface of the sprue 16 may be curved in a concave shape or a convex shape.

  In the sprue 16 having a trapezoidal longitudinal section, the opening angle (angle θ in FIG. 2B) from the outer end face 14 side to the inner end face 15 side is preferably preferably 1 to 10 °. 9 ° is more preferable, and 5 ° to 7 ° is particularly preferable. The opening angle of the sprue 16 is an angle at which the extension lines on both side surfaces of the sprue 16 intersect in the cross-sectional view of the first end mold 3 passing through the central axis of the sprue 16 as shown in FIG. θ. The portion with the smallest diameter of the sprue 16, for example, the outer opening 17 of the sprue 16 opened on the outer end face 14, preferably has a diameter of 1 to 10 mm (including a major axis or a diagonal distance). It is particularly preferred to have a diameter of 5 mm (including long axis or diagonal distance). By forming the sprue 16 in such a shape, when the roller is removed from the molding die 1, the burr that remains and hardens in the sprue 16 is integrated with the roller to form the first end die. 3, it is possible to prevent a part of burrs from remaining in the sprue 16, and the cleaning time of the first end mold 3 can be greatly shortened. Further, by making the sprue 16 in such a shape and / or size, the molding material is gently and smoothly injected from the sprue 16, and insufficient filling of the molding material, generation of bubbles in the molding material, and / or It is possible to prevent air bubbles from being caught in the molding material.

  As shown in FIGS. 1 and 2, the second end mold 4 is used when the molding material is injected or the molding material instead of the sprue 16 functioning as a passage when the molding material is injected. The vent 36 is formed with a vent 36 that functions as a gas or molding material discharge path when the is hardened, and is configured in the same manner as the first end mold 3. That is, the second end mold 4 projects in a circumferential direction from a columnar end mold main body 30 having a holding hole 32 for holding the shaft body 51, and one end of the end mold main body 30, A disk-shaped flange 31 that closes the opening of the cylindrical mold 2, and the flange 31 has a thickness smaller than the depth of the holding hole 32 and a vent 36 formed so as to penetrate therethrough. Have. In other words, the second end mold 4 includes a columnar end mold body 30 having a holding hole 32 provided with a flange-shaped flange 31 that closes one opening of the cylindrical mold 2. And the thickness of the collar part 31 is adjusted to be smaller than the depth of the holding hole 32.

  As shown in FIGS. 1 and 2, the vent 36 preferably has a trapezoidal shape extending from the outer end surface 34 side to the inner end surface 35 side, that is, the outer opening in the vent 36, similar to the sprue 16. The opening diameter of the inner opening 38 is preferably larger than the opening diameter of the portion 37. The opening angle of the vent 36 is particularly preferably adjusted to be smaller than the opening angle θ of the sprue 16. Thus, when the opening angle of the vent is reduced, it becomes easy to generate an internal pressure of the molding die at the end of injection of the molding material, and it is effective to suppress molding defects such as remaining weld lines.

  The cylindrical mold 2, the first end mold 3 and the second end mold 4 are each made of a material having a certain degree of strength and heat resistance at the temperature when the molding material is heat-cured. Examples of such materials include copper, copper alloy, brass, bronze, aluminum, aluminum alloy, steel, various types of plated iron, iron alloy, stainless steel, and the like. The cylindrical mold 2, the first end mold 3 and the second end mold 4 are preferably formed of the same material.

  The end mold jig 5 is used when a molding process for molding the elastic layer 52 (that is, a heating process for heating the molding material) is performed. That is, the end mold jig 5 will be described later in a cavity 6 (see FIG. 5) including a cylindrical mold 2, a first end mold 3, a second end mold 4, and a shaft body. When injecting the molding material, it is not mounted on the first end mold 3 but is mounted on the first end mold 3 after injecting the molding material and before performing the heating step. The end mold jig 5 functions to remove the gas appearing on the sprue 16 side of the molding mold 1 and is substantially the same as the first end mold 3 as shown in FIGS. It has a cylindrical body with the same diameter.

  As shown in FIG. 1 and FIG. 3, the end mold jig 5 is attached to the surface in contact with the bottom surface of the first end mold 3 when mounted on the first end mold 3. An annular storage recess 60 that communicates with the outer opening 17 of the sprue 16 is provided. Therefore, the storage recess 60 once receives the molding material that is thermally expanded during heat curing and flows out of the cavity 6, and transfers the molding material to the discharge hole groove 61 described later. The storage recess 60 is positioned below the outer openings of all four sprues 16 and communicates with these sprues 16.

  As shown in FIG. 3, the storage recess 60 has an annular shape centered on the central axis of the end mold jig 5. When the storage recess 60 has an annular shape, the molding material that surrounds the gas is quickly transferred to the discharge hole described later without disturbing the thermal expansion of the molding material injected into the cavity 6, and the gas that appears. Can be effectively removed, and a desired elastic layer 52 can be formed. That is, as shown in FIG. 9, if the storage recess 60 is not a ring but a circular recess, the thermally expanded gas cannot be effectively discharged out of the molding die 1, and the gas in the cavity 6 cannot be discharged. Cannot flow back and the initial object of the present invention cannot be achieved.

  The storage recess 60 only needs to have a width that allows communication with the sprue 16, but is the same as the opening diameter of the outer opening 17 of the sprue 16 in that gas can be efficiently removed together with the molding material. It is preferable to have a width larger than the width or its diameter. This width may be uniform in the depth direction, gradually increased, or gradually decreased.

  The storage recess 60 only needs to have a depth at which the molding material can be received once. However, if the storage recess 60 is too shallow, the gas may not be removed together with the molding material. The gas originally present in the housing recess 60 may flow back into the cavity 6. Accordingly, the storage recess 60 is appropriately determined in consideration of the volume of the cavity 6, the opening diameter of the outer opening 17 of the sprue 16, and the like, for example, adjusted to a depth of 1 to 3.5 mm and 1 to 3.0 mm. It is preferable that the depth is adjusted.

  Although the bottom shape of the storage recess 60 is not particularly limited, as shown in FIGS. 1 and 3B, a shape having no corners such as a semicircle, an ellipse, or a U shape is formed at the bottom. It is preferable in that the molding material hardly remains and the remaining molding material or a cured product thereof can be easily removed.

  When the end mold jig 5 is mounted on the first end mold 3, the end mold jig 5 extends from the storage recess 60 to the surface that contacts the bottom surface of the first end mold 3. The discharge hole groove 61 extends in the radial direction to the outer peripheral surface of the. When the end mold jig 5 is attached to the first end mold 3, the storage recess 60 and the end mold are formed by the bottom surface of the first end mold 3 and the discharge hole groove 61. A discharge hole communicating with the outer peripheral surface of the mold jig 5 is formed. Accordingly, the discharge hole groove 61 discharges the gas to the outside of the end mold jig 5 together with the molding material which is thermally expanded at the time of heat curing and received in the storage recess 60. The discharge hole groove 61 is indicated by the outer opening 17 of the sprue 16 when the end mold jig 5 is attached to the first end mold 3 (its virtual position is indicated by a broken line in FIG. 3A). 2) are formed at intervals of a central angle of 180 ° so as to cross the middle in between. If the discharge hole groove 61 is formed so as to cross the middle between the outer openings 17, the gas can be easily removed together with the molding material. In the present invention, the discharge hole groove 61 does not need to cross the middle between the outer openings 17, and may be formed so as to cross an appropriate position between the outer openings 17.

  As shown in FIG. 3B, the discharge hole groove 61, that is, the discharge hole, particularly preferably extends in the horizontal direction. If the discharge hole groove 61 extends in this direction, the gas can be efficiently removed together with the molding material even if the amount of the molding material to be removed is small. That is, when the discharge hole groove 61 extends downward, the molding material is heated until it hardens to increase the fluidity, and from the inside of the cavity 6 through the sprue 16, the storage recess 60, and the discharge hole due to gravity. A large amount of molding material flows out to the outside. As a result, the molding material injected into the cavity 6 may be insufficient, and a serious problem may occur that the predetermined elastic layer 52 is not formed on the second end mold 4 side.

  The discharge hole groove 61 has only to have a diameter capable of discharging the molding material. However, the discharge hole groove 61 has the same diameter as the depth of the storage recess 60 or its diameter in that gas can be efficiently removed together with the molding material. Preferably it has a diameter larger than the depth. This diameter may be uniform in the extending direction, gradually increased, or gradually decreased.

  The cross-sectional shape perpendicular to the extending direction of the discharge hole groove 61 is not particularly limited, and examples thereof include a semicircular shape, a semielliptical shape, and a U shape. When the cross-sectional shape is semicircular, semi-elliptical, U-shaped or the like, the molding material hardly remains in the discharge hole groove 61, and the remaining molding material or a cured product thereof can be easily removed. . In this example, the cross-sectional shape is a semicircle.

  The end mold jig 5 has an insertion portion 62 that is inserted through the end mold main body 10 in the axial direction thereof. The insertion portion 62 is adjusted to have an inner diameter slightly larger than the outer diameter of the end mold body 10. When the end mold jig 5 is formed longer than the end mold body 10, the insertion portion 62 does not need to penetrate and may be an insertion hole having a bottom portion. In the present invention, when the end mold jig 5 is mounted on the molding die 100 shown in FIG. 8, for example, the through hole 62 may not be formed.

  The end mold jig 5 is made of a material having a certain degree of strength and heat resistance at a temperature when the molding material is heat-cured. Examples of such materials include copper, copper alloy, brass, bronze, aluminum, aluminum alloy, steel, various types of plated iron, iron alloy, stainless steel, and the like. The end mold jig 5 is preferably formed of a softer material than the material of the first end mold 3.

  Next, an example of a molding method for molding the elastic layer 52 on the outer peripheral surface of the shaft body 51 using the molding die 1 (hereinafter sometimes referred to as a molding method according to the present invention) will be described.

  The molding method according to the present invention includes a cylindrical mold 2, a first end mold 3 and a second end mold 4, a first end mold 3 and a second end mold. The molding material is injected into the cavity 6 formed by the shaft body 51 held in the cylindrical mold 2 by 4 through the sprue 16, and the molding material injected into the cavity 6 is heated and cured. An example of the roller 50 having the elastic layer 52 formed by the forming method according to the present invention is a roller 50 shown in FIG.

  In the molding method according to the present invention, first, the shaft body 51 is prepared. The shaft 51 includes, for example, a metal such as iron, aluminum, stainless steel, brass, or an alloy thereof, a resin such as a thermoplastic resin or a thermosetting resin, and carbon black or metal powder as a conductivity-imparting agent for the resin. Using a material such as a conductive resin blended with a body or the like, it is produced in a desired shape by a known method. When the shaft body 51 is required to have conductivity, in addition to the metal and the conductive resin, the surface of the insulating core body formed of the resin or the like is plated by a regular method so that the shaft body 51 is Can be produced. Among the above materials, a metal is preferable and aluminum or stainless steel is particularly preferable from the viewpoint that conductivity can be easily imparted.

  The shaft body 51 may be coated with a primer layer on its outer peripheral surface as desired. The primer for forming the primer layer is dissolved in a solvent or the like as desired, and is applied to the outer peripheral surface of the shaft body 51 according to a conventional method, for example, a dip method or a spray method, and is cured. The primer is not particularly limited. For example, alkyd resin, phenol-modified silicone modified alkyd resin, oil-free alkyd resin, acrylic resin, silicone resin, epoxy resin, fluororesin, phenol resin, polyamide resin, Examples thereof include urethane resins and mixtures thereof. If desired, a crosslinking agent for curing and / or crosslinking the resin can be used. Examples of such a crosslinking agent include isocyanate compounds, melamine compounds, epoxy compounds, peroxides, phenol compounds, and hydrogen siloxane compounds. Etc. The primer layer is formed with a thickness of 0.1 to 10 μm, for example.

  In the molding method according to the present invention, as shown in FIG. 5, the molding die 1 is then assembled, and the shaft body 51 thus created is housed in the molding die 1. Specifically, one end portion of the shaft body 51 is inserted into the holding hole 12 of the first end mold 3 to hold the shaft body 51, and then the held shaft body 51 is the cylindrical mold 2. So that the flange 11 of the first end mold 3 is inserted into one opening of the cylindrical mold 2 so that the opening of the cylindrical mold 2 is closed. The other end of the shaft 51 is inserted into the holding hole 32 of the second end mold 4, and the flange 31 of the second end mold 4 is inserted into the other opening of the cylindrical mold 2. By inserting and closing the opening of the cylindrical mold 2, the molding mold 1 is assembled in a state in which the shaft body 51 is accommodated therein. In this state, the shaft body 51 is sandwiched between the holding holes 12 of the first end mold 3 and the holding holes 32 of the second end mold 4 at both ends, so that the predetermined end in the molding mold 1 is obtained. The position is fixed.

  In the molding method according to the present invention, an injection molding machine or a casting machine for injecting a molding material is prepared. The molding die 1 according to the present invention, in particular, the first end die 3 has a shape in which the end die body 10 protrudes from the outer end surface 14 of the flange portion 11 as described above. The shape of the injection nozzle in an injection molding machine, a casting machine or the like is produced so as to adapt to the shape of the first end mold 3. That is, the injection nozzle has a shape complementary to the shape of the first end mold 3, for example, as shown in FIG. 7, the end mold body 10 is inserted, and the end mold body 10 and the nozzle are inserted. The contact positioning recess 41 for determining the contact position with the tip 40 is formed at the center, and is formed into a ring shape having a molding material injection passage 42 formed through the peripheral wall 43. The injection path 42 is formed at a position corresponding to the position where the sprue 16 of the collar portion 11 is formed.

  Next, in the molding method according to the present invention, as shown in FIG. 7, the cavity 6 formed by the molding die 1 and the shaft body 51 is molded through the sprue 16 of the first end die 3. Inject material. Any method can be used as the method for injecting the molding material into the cavity 6 as long as it is a regular method. For example, the injection is performed by using an injection molding machine or a casting machine having an injection nozzle tip having the above-mentioned shape. And the like. At this time, as shown in FIG. 7, the first end mold 3 has a shape in which the end mold body 10 protrudes from the flange 11 of the cylindrical mold 2 and an injection molding machine. Alternatively, since the nozzle tip 40 of a casting machine or the like has a shape complementary to the shape of the first end mold 3, the injection path 42 of the nozzle tip 40 is accurately positioned with respect to the sprue 16. As a result, the first end mold 3 and the nozzle tip 40 can be brought into contact with each other. Therefore, the arrangement | positioning operation | work of the nozzle front-end | tip part 40 becomes easy, and leakage of the molding material at the time of injection | pouring of a molding material can be prevented.

  In the molding method according to the present invention, the elastic material 52 is then molded by heat-curing the molding material injected into the cavity 6. At this time, as shown in FIG. 1, the end mold jig 5 is mounted below the first end mold 3. A cylindrical end mold jig may be mounted above the second end mold 4. Then, the molding die 1 is preferably in an upright state and pressed with a predetermined pressure from the axial direction. While maintaining this state, the molding material is heated to a temperature at which it can be cured. Then, even if gas appears in the vicinity of the first end mold 3, the entire molding material is thermally expanded, and the molding material surrounding the gas in the vicinity of the first end mold 3 is the cavity. It flows in the direction of gravity where the pressure is lower than in 6. That is, the molding material is discharged to the outside of the molding die 1 through the storage recess 60 and the discharge hole while surrounding the gas. Therefore, the gas that appears in the vicinity of the first end mold 3 is removed from the cavity 6. If the end mold jig 5 is not provided with a discharge hole, the gas that has flowed into the housing recess 60 together with the molding material flows back into the cavity 6 due to the outflow of the new molding material, and is formed. A depression may be formed on the surface. However, according to the molding die 1, the gas existing in the housing recess 60 is discharged together with the molding material to the outside of the molding die 1 and flows back into the cavity 6 by the housing recess 60 and the discharge hole extending therefrom. There is no. Since the discharge hole extends in the horizontal direction, a small amount of molding material may be discharged when removing the gas that has appeared in the molding material and the gas present in the storage recess, and the second end metal The molding material is still filled in the vicinity of the mold 4.

  In this state, it is heated to a temperature at which the molding material is cured. The heating temperature of the molding material is determined according to the molding material. For example, when an addition-curable liquid conductive silicone rubber composition described later is used as a molding material, the heating temperature can be set to 100 to 300 ° C., and the heating time can be set to 10 seconds to 1 hour. it can.

  In this way, the elastic layer 52 can be formed on the outer peripheral surface of the shaft body 51 to manufacture the roller 50 shown in FIG.

  The molding material used in the production method according to the present invention may be a rubber composition containing a rubber that is liquid at room temperature. Examples of liquid rubber include silicone or silicone-modified rubber, nitrile rubber, and ethylene propylene rubber ( Ethylene propylene diene rubber), liquid rubbers such as styrene butadiene rubber, butadiene rubber, isoprene rubber, natural rubber, acrylic rubber, chloroprene rubber, butyl rubber, epichlorohydrin rubber, urethane rubber, fluorine rubber and the like. These rubbers are preferably an addition-curing type because they are excellent in dimensional accuracy during heat molding.

  The rubber composition may contain various additives usually contained in the rubber composition in addition to rubber. Examples of the various additives include vulcanizing agents, vulcanization accelerators, and vulcanization accelerators. Auxiliary agent, vulcanization retarder, conductivity imparting agent, dispersant, foaming agent, anti-aging agent, antioxidant, filler, pigment, colorant, processing aid, softener, plasticizer, emulsifier, curing agent, Examples thereof include a heat resistance improver, a flame retardant improver, an acid acceptor, a heat conductivity improver, a release agent, and a solvent. These various additives may be commonly used additives or may be specially used additives depending on applications.

  The rubber composition may have a viscosity of, for example, 5 to 500 Pa · s at 25 ° C. in that it can be easily and uniformly injected into the molding die 1, and 10 to 200 Pa · s. It is particularly good to have a viscosity of

Specifically, as such a rubber composition, for example, (A) an organopolysiloxane containing at least two alkenyl groups bonded to a silicon atom in one molecule; and (B) a silicon atom in one molecule. An organohydrogenpolysiloxane containing at least two hydrogen atoms to be bonded; (C) an inorganic filler having an average particle diameter of 1 to 30 μm and a bulk density of 0.1 to 0.5 g / cm ³ ; Examples thereof include an addition-curable liquid conductive silicone rubber composition containing D) a conductivity imparting agent and (E) an addition reaction catalyst.

  According to the manufacturing method of the present invention, since the elastic layer 52 can be formed on the outer peripheral surface of the shaft body 51 using the molding die according to the present invention, gas is injected into the molding material injected into the cavity 6. Even when a small amount of the molding material appears, the gas can be discharged from the cavity 6 together with a small amount of the molding material, and the flat elastic layer 52 can be formed on the outer peripheral surface of the shaft body 51.

  The molding method according to the present invention is not limited to the above-described example, and various modifications can be made within a range in which the object of the present invention can be achieved. For example, in the molding method according to the present invention, if desired, it may be heated again (secondary heating) after the heat-curing, and the end portion of the molded elastic layer may be cut off if desired.

  The molding die according to the present invention is not limited to the above-described example, and various modifications can be made within a range in which the object of the present invention can be achieved. That is, in the molding die 1 as an example of the molding die according to the present invention, the storage recess 60 is connected to all the sprues 16, but in this invention, the storage recess is connected to all the sprues. For example, as shown in FIG. 4A, the housing recess has two sprues (the sprue 16 when the end mold jig is mounted on the first end mold). The virtual position may be divided into two pieces so as to be connected to each other. Furthermore, a plurality of storage recesses may be formed independently so as to be connected to only one sprue, or may be divided to be connected to three sprues. When a plurality of storage recesses are formed, it is preferable that the plurality of storage recesses have the same shape and volume.

  Further, the molding die 1 as an example of the molding die according to the present invention has two discharge hole grooves 61 (that is, two discharge holes). The number of grooves (that is, discharge holes) is not particularly limited, and may be one or three or more. For example, as shown in FIG. 4B, four discharge hole grooves 61 may be formed at a central angle of 90 °. In this case, the sprue 16 adjacent to each other at the virtual position of the sprue 16 (shown by a broken line in FIG. 4B) when the end mold jig 5 is mounted on the first end mold 3. And the discharge hole groove 61 are preferably positioned at an angle of 45 °.

  Further, a molding die 1 as an example of the molding die according to the present invention includes a first end mold 3 and a second end mold 4 having the same structure. In the molding die according to the above, it is not necessary that the first end die and the second end die have the same structure.

  Further, in a molding die 1 as an example of the molding die according to the present invention, a first end die 3 and a second end die 4 are inserted into both end openings of the cylindrical die 2. Thus, the cylindrical mold 2 and the first end mold 3 are fitted, and the cylindrical mold 2 and the second end mold 4 are fitted, so that the cylindrical mold 2 Although the opening portions at both ends are closed, in this invention, both ends of the cylindrical mold are in contact with the inner end surfaces of the flanges of the first end mold and the second end mold. The both end openings of the cylindrical mold may be closed by contact, and the outer edge of the flange portion of the first end mold and the second end mold may be, for example, a flange, an engaging convex portion, etc. And fitting means such as notches and engaging recesses are formed at both ends of the cylindrical mold, and these fitting means are fitted to form the cylindrical mold. Type Both end openings may be closed.

  Further, in the first end molds 3 and 5 constituting the molding die as an example of the molding die according to the present invention, four sprues 16 penetrate the flange portion 11 as shown in FIG. Although formed, in this invention, the number by which the sprue is formed to penetrate the collar portion of the first end mold is not particularly limited, and may be one or two or more.

(Example 1)
A molding die 1 shown in FIGS. 1 and 2 was prepared. The cylindrical mold 2 was formed into a cylindrical shape having a total length of 240 mm, an outer diameter of 35 mm, and an inner diameter of 20.7 mm using NAK55 (plastic mold steel, manufactured by Daido Steel Co., Ltd.). Each of the first end mold 3 and the second end mold 4 uses S50C (steel for machine structure, manufactured by Daido Amister Co., Ltd.), the thickness of the collar 2 mm, the diameter 20.7 mm, the end The outer diameter of the part mold body was adjusted to 10 mm, its length (excluding the thickness of the collar part) 45 mm, the depth of the holding hole (including the thickness of the collar part) 22.75 mm, and the inner diameter 7.5 mm. The sprue and vent are respectively adjusted to have an opening diameter of 2.7 mm at the inner opening and an opening diameter of 2.5 mm (opening angle θ6 °) at the outer opening, and 4 at regular intervals on a circumference of 8 mm from the center of the flange. Individually formed.

  The end mold jig 5 is a cylindrical body having an outer diameter of 35 mm and an axial length of 30 mm, in which an insertion portion 62 having an inner diameter of 10 mm is drilled using S50C (steel for machine structure, manufactured by Daido Amister Co., Ltd.). On the upper surface, a semicircular annular recess 60 having a width of 3 mm, a depth of 3 mm, and an inner diameter of 16.5 mm and two semicircular discharge hole grooves 61 having a width of 4 mm and a depth of 4 mm are formed. did. The two discharge hole grooves 61 have a central angle of 180 ° so that the end mold jig 5 is positioned at the substantially central portion of the two sprues 16 when the end mold jig 5 is mounted on the first end mold 3. Formed at intervals of As the end mold jig 63 attached to the second end mold, an outer diameter in which an insertion portion 62 having an inner diameter of 10 mm is drilled using S50C (steel for machine structure, manufactured by Daido Amister Co., Ltd.). It was molded into a cylindrical body having a length of 35 mm and an axial length of 30 mm. The inner surface of the cylindrical mold 2 was polished according to a conventional method.

  Further, the shaft body 51 (made by SUM22, diameter 7.5 mm, length 281.5 mm) subjected to electroless nickel plating treatment was washed with toluene, and a silicone primer (trade name “Primer No. 16”) was formed on the surface thereof. , Manufactured by Shin-Etsu Chemical Co., Ltd.). The shaft body subjected to the primer treatment was fired at a temperature of 150 ° C. for 10 minutes using a gear oven, and then cooled at room temperature for 30 minutes or more to form a primer layer on the surface of the shaft body 51.

Further, an addition curable liquid conductive silicone rubber composition was prepared as follows. That is, 100 parts by mass of dimethylpolysiloxane (A) (degree of polymerization 300) blocked at both ends with dimethylvinylsiloxy groups, and a hydrophobized fumed silica having a BET specific surface area of 110 m ² / g (Nippon Aerosil Co., Ltd.) Made by company, R-972) 1 part by mass, average particle size 6 μm, bulk density of 0.25 g / cm ³ diatomaceous earth (C) (Oplite W-3005S, manufactured by Hokuaki Diatomite Co., Ltd.) 40 parts by mass, and 5 parts by mass of acetylene black (D) (Denka Black HS-100, manufactured by Denki Kagaku Kogyo Co., Ltd.) was put into a planetary mixer, stirred for 30 minutes, and then passed once through three rolls. This is returned to the planetary mixer again, and methylhydrogenpolysiloxane (B) having Si—H groups at both ends and side chains as a crosslinking agent (polymerization degree 17, Si—H amount 0.0060 mol / g) 2. 1 part by mass, 0.1 part by mass of ethynylcyclohexanol as a reaction control agent and 0.1 part by mass of a platinum catalyst (E) (Pt concentration 1%) are added and stirred and kneaded for 15 minutes. The product was a silicone rubber composition.

  Next, a mold release agent (trade name “Dai Free”, manufactured by Daikin Industries, Ltd.) is applied to the inner surface of the formed mold 1, and as shown in FIG. 5, the first end mold 3 The molding die 1 was assembled by holding the shaft 51 in the cylindrical mold 2 with the holding hole 12 and the holding hole 32 of the second end mold 4. Next, as shown in FIG. 7, the nozzle tip 40 is attached to the first end mold 3, and the silicone rubber composition is added from the sprue 16 of the first end mold 3 to the second end mold 3. It poured until it began to flow out from the vent 36 of the end mold 4.

Next, as shown in FIG. 1, the end mold jig 5 is attached to the first end mold 3, the molding mold 1 is placed upright, and 200 kg / cm ² from the axial direction thereof. Pressed with the pressure of. While maintaining this state, the silicone rubber composition was heated and molded at 150 ° C. from the outside of the molding die 1 and held at the same temperature for 10 minutes to heat mold the silicone rubber composition. At this time, a molding material of about 2 cm ³ was discharged from the discharge hole of the end mold jig 5, and a plurality of gases were contained in the discharged molding material.

  Next, after the heat molding, the molding die 1 was allowed to cool and the molded product was taken out from the molding die 1. The roller I was prepared by cutting and removing the portion where the excess material such as burrs cured in the sprue 16 and the vent 36 was adhered. In this way, 10 rollers I were formed.

(Example 2)
Instead of the end mold 5, as shown in FIG. 4B, the same as in Example 1 except that an end mold jig having four discharge hole grooves 61 is used. Thus, 10 rollers II were formed. When the molding material was heated, about 2 cm ³ of the molding material was discharged from the discharge hole of the end mold jig 5, and a plurality of gases were contained in the discharged molding material.

(Comparative Example 1)
10 pieces in the same manner as in Example 1 except that the end mold jig 63 (no storage recess and no discharge hole groove formed) is used instead of the end mold jig 5. The roller III was molded.

(Comparative Example 2)
Instead of the end mold jig 5, a semicircular annular recess 60 having a width of 3 mm, a depth of 3 mm, and an inner diameter of 16.5 mm, and a discharge hole extending in the axial direction from the bottom surface of the storage recess 60 to the outside Ten rollers IV were molded in the same manner as in Example 1 except that an end mold jig having a circular section with a diameter of 3 mm was used. When the molding material was heated, about 4 cm ³ of the molding material was discharged from the discharge hole of the end mold jig, and the discharged molding material contained a plurality of gases.

(Comparative Example 3)
Example except that instead of the end mold jig 5, an end mold jig in which only a semicircular annular recess 60 having a width of 3 mm, a depth of 4 mm and an inner diameter of 16.5 mm was formed was used. In the same manner as in No. 1, ten rollers V were formed.

  The elastic layers 52 of the rollers I to V thus formed were visually confirmed. As a result, in all of the rollers I and II, it was not possible to confirm the presence of the depressed portion in the elastic layer on the first end mold 3 side, and a flat elastic layer was formed. On the other hand, in three of the ten rollers III, a plurality of depressions existed on the surface and inside of the elastic layer on the first end mold 3 side. In addition, in seven of the ten rollers IV, it was not possible to confirm the presence of the depressed portion in the elastic layer, but in all the rollers IV, the elasticity of the second end mold 4 side was confirmed. The layer length was insufficient. Further, in all the rollers V, a large number of depressions exist in the elastic layer on the first end mold 3 side.

FIG. 1 is a schematic sectional view showing an example of a molding die according to the present invention. FIG. 2 is a schematic view showing an example of a first end mold constituting the molding die according to the present invention, and FIG. 2A is a first end constituting the molding die according to the present invention. FIG. 2B is a schematic vertical sectional view showing an example of a first end mold constituting the molding die according to the present invention. FIG. 3 is a schematic view showing an example of an end mold jig constituting the molding die according to the present invention, and FIG. 3A is an end mold jig constituting the molding die according to the present invention. It is a schematic top view which shows an example of a tool, FIG.3 (b) is a schematic sectional drawing which shows the cross section of the AA line in Fig.3 (a). FIG. 4 is a schematic view showing another example of an end mold jig constituting the molding die according to the present invention, and FIG. 4 (a) is a storage recess constituting the molding die according to the present invention. FIG. 4B is a schematic top view showing another example of the two end mold jigs formed, and FIG. 4B is a view showing that four discharge hole grooves constituting the molding die according to the present invention are formed. FIG. 10 is a schematic top view showing another example of the end mold jig. FIG. 5 is a schematic sectional view showing a state in which the shaft body is housed in the molding die according to the present invention. FIG. 6 is a schematic perspective view showing an example of a roller. FIG. 7 is a schematic sectional view for explaining a contact state between the molding die and the nozzle according to the present invention. FIG. 8 is a schematic cross-sectional view showing an example of a conventional molding die. FIG. 9 is a schematic cross-sectional view showing another example of a conventional molding die.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Molding die 2 Cylindrical die 3 1st end part mold 4 2nd end part mold 5 End part mold jig 6 Cavity 10, 30 End part mold body 11, 31 Gutter part 12, 32 Holding hole 13, 33 Holding hole bottom surface 14, 34 Outer end face 15, 35 Inner end face 16 Sprue 17, 37 Outer opening 18, 38 Inner opening 36 Vent 40 Nozzle tip 41 Contact positioning recess 42 Injection channel 43 Circumferential wall 50 Roller 51 Shaft body 52 Elastic layer 60 Housing recess 61 Discharge hole groove 62 Insertion part 63 End mold jig 100 Molding die 101 Cylindrical mold 102 Other end part mold 103 One end part mold 104 Injection hole 105 Liquid Reservoir 106 One end mold

Claims (1)

A cylindrical mold, a first end mold having a sprue through which a molding material circulates and closing one opening in the cylindrical mold, and the other opening in the cylindrical mold are closed. A second end mold having a vent, and an end mold jig mounted on the first end mold at the time of heat molding,
A molding die comprising: a storage recess continuously provided in an outer opening of the sprue; and a discharge hole extending from the storage recess.

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