JP4510574B2 - Rubber roller manufacturing method and molding die - Google Patents

Description

  The present invention relates to a method for manufacturing a rubber roller and a molding die, in which a liquid rubber material is injected into a molding die and cured in various rubber rollers used in office automation equipment such as a printer and a copying machine. .

  Generally, a rubber roller manufactured by injecting a liquid rubber material into a molding die is composed of at least three members: a cylindrical pipe mold and pieces attached to both ends thereof. At least one of the end pieces is provided with one or more injection ports for injecting the liquid rubber material. Generally, when there are a plurality of injection ports, there is a material reservoir for distributing the liquid rubber material to the plurality of injection ports before the injection port. This material reservoir may have its function in the molding die itself, or when the molding die is set in the apparatus for injecting the liquid rubber material, the molding die and the liquid rubber material are injected. It may be formed between the devices. At this time, the shape of the liquid reservoir is generally a cylindrical shape because a concave surface is provided on the outer end face of the end piece to form a material reservoir, or conversely, a concave surface is provided on the apparatus side for injecting the liquid rubber material to form a material reservoir. (For example, see Patent Documents 1 and 2).

When the liquid rubber material is injected into the mold cavity, the liquid rubber material is injected and injected into the material reservoir, and the liquid rubber material is injected into the mold cavity through a plurality of injection ports. At this time, if the material injection speed is increased by shortening the production tact, etc., there is a possibility that air may be involved. That is, the liquid rubber material injected into the liquid reservoir spreads in the circumferential direction on the outer end face of the end piece, reaches a plurality of injection ports, and is fed into the mold cavity. The air in the reservoir does not escape and the material entrains the air. This air entrainment becomes a concave defect on the surface of the rubber roller when it is molded and cured.
Japanese Patent Laying-Open No. 2003-039452 (Claim 9, FIG. 1) JP 2003-191244 A (Claim 4, FIG. 1)

  Accordingly, an object of the present invention is to provide a rubber roller manufacturing method and a molding die with less entrainment of bubbles.

The present invention consists of at least 3 members of the frames to be fitted into the pipe mold body and both ends thereof, a plurality of inlets for injecting a rubber material into the forming metal mold cavity, a rubber material is arranged in front the inlet the rubber roller shaft body disposed within the molding die with the wood charge reservoir you distributed to multiple infusion inlet, injecting the rubber material of the liquid within the molded metal mold cavity, a rubber roller to mold cured In the manufacturing method, the material reservoir portion has a width of 1 to 1.5 times that of the injection port, and a cross-sectional area gradually decreases toward the injection port. A ring-shaped groove is formed, and a central convex portion having a middle and high conical shape is formed inside the groove, and the central convex portion forms an inner wall surface of the groove to form the pipe mold. A first inclined surface having a first inclination angle with respect to the central axis, and an upper end of the inner wall surface; And an inclined toward the Luo center second inclined surface having a second inclined angle with respect to the pipe mold center axis, once inclined groove portion the flow direction of the rubber material in the material reservoir After spreading in the circumferential direction, the problem was solved by injecting the rubber material from the groove into the inlet .

Further, the first inclination angle is 2 ° or more and less than 60 °, the second inclination angle is 30 ° or more and less than 80 °, and the central convex portion is a separate member from the piece, The problem has been solved by the fact that the central convex portion is a pre-hardened steel member .

  According to the rubber roller manufacturing method of the present invention, the material flow direction is once expanded in the circumferential direction in the material reservoir portion, and the shape of the material reservoir portion in the vicinity of the material injection port has a cross-sectional area toward the injection port. Since the ring shape is reduced, the material is injected while pushing out air in the liquid reservoir, and the retention of the liquid rubber material is reduced, so that a rubber roller with less air entrainment can be formed. In particular, when the liquid rubber material is injected from the lower part of the mold in a state where the mold is set up by making the material flow direction extending in the circumferential direction an acute angle with respect to the mold central axis, the injection path of the liquid rubber is always Since it goes upward, the air in the liquid reservoir is smoothly pushed out, and the entrainment of air is further reduced.

The present invention is composed of at least 3 members of the frames to be fitted into the pipe mold body and both ends thereof, a plurality of inlets for injecting a rubber material into the forming metal mold cavity, a rubber material is arranged in front the inlet the rubber roller shaft body disposed within the molding die with the wood charge reservoir you distributed to multiple infusion inlet, injecting the rubber material of the liquid within the molded metal mold cavity, a rubber roller to mold cured In the manufacturing method, the material reservoir portion has a width of 1 to 1.5 times that of the injection port, and a cross-sectional area gradually decreases toward the injection port. A ring-shaped groove is formed, and a central convex portion having a middle and high conical shape is formed inside the groove, and the central convex portion forms an inner wall surface of the groove to form the pipe mold. A first inclined surface having a first inclination angle with respect to the central axis, and an upper end of the inner wall surface; And an inclined toward the Luo center second inclined surface having a second inclined angle with respect to the pipe mold center axis, once inclined groove portion the flow direction of the rubber material in the material reservoir After expanding in the circumferential direction, the rubber material is injected from the groove into the injection port . Next, the present invention will be described in more detail with reference to preferred embodiments.

  There is no particular limitation on the method of expanding the material flow direction in the circumferential direction once in the material reservoir and reducing the cross-sectional area of the shape of the material reservoir near the material inlet toward the inlet. There is a method in which a ring-shaped groove is formed on the outer end face of the end piece, and a plurality of the inlets are created from the bottom of the groove. At this time, the ring-shaped groove is inclined so that the cross-sectional area decreases toward the back. Further, the shape of the end piece may be processed so that the outer end face itself of the end piece has a convex portion that becomes the inner side of the ring groove. Moreover, you may attach the another member which has a convex part shape used as the inner side of a ring groove to the outer side end surface of this end piece. Preferably, a ring shape is formed on the outer end face of the end piece, and another member having a convex shape may be attached depending on the mold configuration.

  The ring shape of the material reservoir is not particularly defined, but the width is preferably 1 to 1.5 times that of the injection port, and the ring-shaped cross-sectional area is gradually reduced toward the injection port. There is no particular restriction on the taper angle when reducing the cross-sectional area of the ring shape, but it is preferably 2 ° or more in consideration of air extrudability and releasability of the liquid reservoir. Considering the size of the liquid reservoir, it is preferably less than 60 °.

  In addition, as a method of making the material flow direction extending in the circumferential direction an acute angle with respect to the mold center axis, there is no particular limitation, but the shape of the convex portion inside the ring groove is a conical shape with a middle middle height, Correspondingly, another member is prepared in the molding die, and the shape thereof is a mortar shape having a concave central portion. By combining these, the material flow direction becomes an acute angle with respect to the central axis of the die. Further, instead of the mold-specific member having a concave mortar shape, a central concave mortar shape may be provided at a contact portion with the molding die in the apparatus for injecting the liquid rubber material. At this time, the angle with the central axis is preferably 80 ° or less in consideration of air extrudability. Further, when the angle with the central axis is small, the molding die itself is disadvantageously long, and is preferably 30 ° or more.

  An embodiment in which the method for producing a rubber roller of the present invention is applied to molding of a developing roller for electrophotography will be described with reference to the drawings. As shown in FIG. 1, as shown in FIG. 1, a pipe mold body 2 having a cylindrical shape having an inner diameter of φ16 mm and a length of 250 mm, an upper piece 1 and a lower piece 3 fitted to both ends of the mold body, Then, a molding die constituted by four parts of the touch piece 4 for forming a material pool by combining with the lower piece and inserting an injection nozzle when injecting the liquid rubber material was used. The material of the molding die is prehardened steel. The bottom piece has a bottom diameter of 18mm, a depth of 5mm, and a slope of 5 ° on the outer edge, and a hole with a pitch diameter of 14mm and a diameter of 2mm is equally distributed around the bottom of the recess as a material injection hole. 8 places are opened. In addition, the upper piece is provided with four φ2 mm holes at equal distributions for air bleeding and material overflow. The shape of the touch piece is an R surface at the contact point with the lower piece, the lower piece side end face is horizontal, a φ4mm through hole is in the center, and a taper for inserting the injection nozzle in the center of the outer end face. A hole is provided.

  Further, as shown in FIG. 5, the molding apparatus used for material injection and curing is a two-component material pump 16. A material supply unit consisting of material mixing 15, injection syringe 14, injection motor 14b, three-way valve 13, injection The material injection portion is composed of a nozzle 12, and the curing portion is composed of a heat plate 10, a lower heat plate 10b, a mold retainer 11, and a mold retainer cylinder 11b.

( Reference Example 1)
As reference example 1, as shown in FIG. 2, a conical prehardened steel member 3b having a bottom surface of φ12 mm, a height of 2 mm, and an inclination angle of 15 ° is attached to the central portion of the concave portion on the outer end surface of the lower piece, and the material reservoir 6 The developing roller was molded using a molding die in which the ring shape was formed. At this time, the width of the ring-shaped liquid reservoir immediately before the injection port is 3 mm, which is 1.5 times that of the injection port (injection hole) 7. For forming the developing roller, a shaft body 5 (made of free-cutting steel SUM23L) having an outer diameter of φ8 mm and a length of 270 mm is arranged inside the mold, and an injection nozzle is pressed against the touch piece to form a liquid silicone rubber material of 40 cc. Injection injected into the mold. The injection speed at this time was 10 cc / second at the maximum, and 40 cc of liquid silicone rubber material was injected and injected into the mold cavity in 10 seconds by varying the injection speed. The liquid silicone rubber material used for molding is a two-component mixed thermosetting silicone rubber having a viscosity of 150 Pa · s. Moreover, carbon black is blended in order to give conductivity. After injection of the liquid silicone rubber material, the molding die was put into a 110 ° C. hot plate for 5 minutes to cure the rubber material, and after cooling to 30 ° C., the rubber roller was taken out of the molding die.

(Example 1 )
As shown in FIG. 3 as Example 1 , a conical pre-hardened steel member having a two-step inclination angle with a bottom surface of φ12 mm, a height of 2.5 mm, a bottom surface inclination angle of 10 °, and a tip end of 80 °. It was attached to the center of the recess on the outer end face of the lower piece, and a ring shape of the material reservoir 8 was formed. In addition, a mortar-shaped recess was provided at the center of the lower piece side end face of the touch piece, and the angle of the material flow direction spreading in the circumferential direction by the combination of the touch piece and the lower piece was set to 80 ° with respect to the central axis. As in Reference Example 1, a liquid silicone rubber material was injected and injected to form a rubber roller. In molding, the same molding die as in Reference Example 1 is used for the convex member attached to the lower piece, the pipe type other than the touch piece, and the upper and lower pieces, and the rubber material and the molding conditions are the same as in Reference Example 1.

(Comparative Example 1)
As Comparative Example 1, as shown in FIG. 4, a convex member was not attached to the central part of the concave portion on the outer end surface of the lower piece, and the touch piece was the same as that of Reference Example 1, with a flat state. At this time, the shape of the liquid reservoir 9 is a conical column shape having a lower surface of 8.7 mm, an upper surface φ of 18 mm, and a height of 4 mm, and does not have a ring shape. The same as liquid silicone rubber material was injected injected in Reference Example 1, it was molded rubber roller. In molding, the pipe mold, the upper and lower pieces, and the touch piece use the same molding die as in Reference Example 1, and the rubber material and molding conditions are the same as in Reference Example 1.

The outer surface of the rubber roller molded in Example 1, Reference Example 1 and Comparative Example 1 was visually observed to confirm the presence or absence of a recess due to air entrainment. As shown in Table 1, according to the present invention, the recess due to entrainment of air was confirmed. It can be confirmed that the occurrence of

2 is a schematic view of a molding die used in Reference Example 1. FIG. 5 is a schematic view of a cross section of a liquid reservoir of a molding die used in Reference Example 1. FIG. 2 is a schematic view of a cross section of a liquid reservoir of a molding die used in Example 1. FIG. 6 is a schematic view of a cross section of a liquid reservoir of a molding die used in Comparative Example 1. It is the schematic of the apparatus used for shaping | molding of the rubber roller of an Example , a reference example, and a comparative example.

Explanation of symbols

1. Upper piece 2. 2. Pipe mold body Lower piece 4. Touch piece 5. Rubber roller shaft 6. 6. Liquid reservoir cross-sectional shape shown in Reference Example 7 Inlet 8. 8. Liquid reservoir cross-sectional shape shown in Example 1 10. Liquid reservoir cross-sectional shape shown in Comparative Example 1 Hot plate 10b. Lower heating plate 11. Mold presser 11b. Mold presser cylinder 12. Injection nozzle 13. Three-way valve 14. Injection syringe 14b. Injection motor 15. Material mixing16. Material pump

Claims (8)

Composed of at least 3 members of the frame to be fitted pipe mold body and its both ends, forming metal mold and a plurality of inlets for injecting a rubber material into the cavity, a plurality of the rubber material is provided in front the inlet Note the rubber roller shaft body disposed within the molding die with the wood charge reservoir you distributed to the inlet, injecting the rubber material of the liquid within the molded metal mold cavity, in the manufacturing method of the rubber roller of molding by curing ,
The material reservoir has a ring-shaped groove in which the connection portion with the plurality of injection ports has a width of 1 to 1.5 times that of the injection port and the cross-sectional area gradually decreases toward the injection port. And a central convex portion having a middle and high conical shape is formed inside the groove, and the central convex portion forms an inner wall surface of the groove, and is formed with respect to the central axis of the pipe mold. A first inclined surface having an inclination angle of 1, and a second inclined surface inclined from the upper end of the inner wall surface toward the center and having a second inclination angle with respect to the center axis of the pipe mold,
A method of manufacturing a rubber roller , wherein the flow direction of a rubber material is once expanded in a circumferential direction inclined to the groove portion in the material reservoir portion , and then the rubber material is injected from the groove portion into the injection port. 2. The method of manufacturing a rubber roller according to claim 1, wherein the first inclination angle is 2 ° or more and less than 60 °, and the second inclination angle is 30 ° or more and less than 80 °. The rubber roller manufacturing method according to claim 1, wherein the central convex portion is a separate member from the piece. The rubber roller manufacturing method according to claim 3, wherein the central convex portion is a pre-hardened steel member. Composed of at least 3 members of the frames to be fitted pipe mold body and its both ends, forming metal mold and a plurality of inlets for injecting a rubber material into the cavity, a plurality of the rubber material is provided in front the inlet Note the rubber roller shaft body disposed within the molding die with the wood charge reservoir you distributed to the inlet, injecting the rubber material of the liquid within the molded metal mold cavity, the molding die of the rubber roller to mold cured In
The material reservoir has a ring-shaped groove in which the connection portion with the plurality of injection ports has a width of 1 to 1.5 times that of the injection port and the cross-sectional area gradually decreases toward the injection port. And a central convex portion having a middle and high conical shape is formed inside the groove, and the central convex portion forms an inner wall surface of the groove, and is formed with respect to the central axis of the pipe mold. A first inclined surface having an inclination angle of 1 and a second inclined surface inclined from the upper end of the inner wall surface toward the central portion and having a second inclination angle with respect to the central axis of the pipe mold. A molding die for a rubber roller. The rubber roller molding die according to claim 5, wherein the first inclination angle is 2 ° or more and less than 60 °, and the second inclination angle is 30 ° or more and less than 80 °. The rubber roller molding die according to claim 5 or 6, wherein the central convex portion is a separate member from the piece. The rubber roller molding die according to claim 7, wherein the central convex portion is a pre-hardened steel member.

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