JP3869024B2 - Manufacturing method and manufacturing apparatus for injection molded magnet roll - Google Patents

Description

上記成形条件で通常の射出成形法と本発明の射出成形法によりマグネットロールを作製し、成形サイクルタイムと出来上がった成形体の反りの大きさを測定した。反りの測定は図１４に示すようにマグネットロールＭの両端部を支持し、反りの全くない基準棒と基準面との距離をｄ１とし、測定するマグネットロールＭの基準面からの距離をｄ２としたときに、これら距離相互の差（ｄ１−ｄ２）を求めてこれを「反りの大きさ」とした。結果を表１に示す。
【００３６】
【表１】

この表に示されているように、本発明方法によれば成形のサイクルタイムを大幅に短縮化しても反りの小さいマグネットロールが作製可能となる。
【００３７】
「比較試験２：冷却時間と反りの関係について」
比較試験１と同一の条件で、冷却時間（保圧・計量・冷却の時間の総和）を変えて成形体の反りの大きさを調べた。結果を表２に示す。
【００３８】
【表２】

表２において「変形極めて大」と記載したものは、エジェクトピンによって押された部分が「くの字」状に変形してしまい正確な測定ができなかったことを示している。
表２より、本発明の製造方法により作製したマグネットロールは短い冷却時間であっても、その反り量は極めて小さい。したがって従来の射出成形法に比べて冷却時間の大幅な短縮が可能であり、この表からも本発明は生産性に極めて優れていることが確かめられた。尚、本発明でも８０μｍ前後の反りが発生しているのはキャビティ内で冷却固化する際に、温度の不均一が生じ、成形体内部に熱収縮の差ができたためと推測される。
このように本発明は、金型内で固化した成形体を成形体長手方向に引き出すか、あるいは押し出すことによって金型から成形体を離型させることにしたので、成形体の長手方向に垂直な方向からエジェクトピンで成形体を押すことによって成形体を金型から離型させる従来の射出成形法に比べて、成形体の反りを大幅に低減させることが可能である。そして成形体が充分に冷却しない段階であっても、成形体に反りを発生させることなく、あるいはその反り量が実用上問題とならない範囲内に抑えた状態で成形体を金型から取り出すことができるので、成形サイクルの大幅な短縮化も可能となる。
【００３９】
【発明の効果】
本発明の製造方法は、従来の射出成形法に比べて次の諸点で優れている。
▲１▼成形体は当該成形体の長手方向に沿って引き出すか、又は押し出すことによって金型から取り出すために離型時の反りが発生しにくい。また、金型から取り出す成形体の冷却時間は従来の射出成形法の冷却時間に比べて大幅に短縮できるため、生産性の飛躍的な向上がはかれる。
▲２▼本発明ではキャビティ内周面にはパーティング面が存在しない筒状金型を用いていることから、従来の射出成形金型の問題点であったパーティング面の集中磨耗がなくなり金型寿命が長くできる。
▲３▼筒状金型内面にバリ防止用の「肉盗み」としての切り欠き面が存在しないので磁極配置に制限がなく、磁界パターン設計の自由度が高まる。
【００４０】
成形空間内面の表面荒さはＲ_max 値で１Ｓ以下であり、また成形空間の内径寸法の長手方向ばらつきが２０μｍ以下である場合、成形体と筒状金型との摩擦抵抗は低く抑えられ、筒状金型からの成形体の離型は容易であり、また取り出した成形体の表面も平滑である。
【００４１】
また、移動させる側の金型である可動型の端部形成部位に、成形体の抜き取り方向に向かって僅かに縮径する逆勾配を与えたり、あるいは端部形成部位内面に僅かな突起を設けた場合、この逆勾配や突起による引っ掛かりによって成形体は可動型の移動に追随するので成形体を可動型の移動に追随させるための特別な他の工夫は不要となる。
【図面の簡単な説明】
【図１】 マグネットロールの外観を示す斜視図
【図２】 本発明の参考例において金型内に磁石材料を射出充填した段階を示す断面説明図
【図３】 同参考例において、成形体を伴いながら可動型を固定型に対して型開きした状態を示す断面説明図
【図４】 同参考例において、エジェクトピンにより可動型から成形体を押出し、且つこの成形体をロボットアームで把持した状態を示す断面説明図
【図５】 同参考例において、ロボットアームで把持された成形体から可動型を引き取った状態を示す断面説明図
【図６】 同参考例において可動型の軸端部分に逆勾配を与える例を示す断面説明図
【図７】 本発明の代表的実施例において金型内に磁石材料を射出充填した段階を示す断面説明図
【図８】 同実施例において、成形体を伴いながら可動型を固定型に対して型開きして成形体を固定型から引き出す状態を示す断面説明図
【図９】 同実施例において、エジェクトピンにより可動型から成形体を押出した状態を示す断面説明図
【図１０】 同実施例において可動型の軸端部分に逆勾配を与える例を示す断面説明図
【図１１】 本発明における金型の磁極配置を示す横断面図
【図１２】 励磁源として永久磁石を用いた場合の金型の横断面図
【図１３】 励磁源として電磁石を用いた場合の金型の横断面図
【図１４】 マグネットロールの反りの比較試験方法を示す説明図
【図１５】 従来の射出成形法において金型内に磁石材料を射出充填した段階を示す断面説明図
【図１６】 従来の射出成形法において金型を型開きした状態を示す断面説明図
【図１７】 従来の射出成形法においてエジェクトピンを突き出して成形体を取り出す様子を示す断面説明図
【図１８】 従来の金型の磁極配置を示す横断面図
【符号の説明】
ａ１ 割型 ａ２ 割型
Ｍ マグネットロール Ｍ１ 主部
Ｍ２ 軸部 Ｍ３ 軸部
Ｍ２１ 第１軸部 Ｍ２２ 第２軸部
１ 可動型 ２ 固定型
３ 成形空間
３ａ 成形空間 ３ｂ 成形空間
４ エジェクトピン ５ ホットゲート
６ ロボットアーム
７ａ，７ｂ，７ｃ，７ｄ 磁性材 ８ 非磁性材
１１ 可動型 １２ 固定型
１３ 成形空間
１３ａ 成形空間 １３ｂ 成形空間
１４ エジェクトピン １５ ホットゲート
２０ 成形空間 ２１ 永久磁石
２２ バックヨーク ２３ 非磁性
２４ 冷却水路
３０ 成形空間 ３１ ヨーク
３２ コイル ３３ バックヨーク
３４ 非磁性材部 ３５ 冷却水路[0001]
[Industrial application fields]
  The present inventionIsMagnet rollers used for developing rolls, cleaning rolls, and transport rolls in electrophotographic developing devices such as copying machines, facsimiles, and printers.Made of leThe present invention relates to a manufacturing method and a manufacturing apparatus thereof.
[0002]
[Prior art]
CopyIn an electrophotographic developing apparatus such as a machine, a facsimile, or a printer, a developing roll, a cleaning roll, and a magnet roll such as a transport roll are used. In addition to these, the use object of the magnet roll is expanding.
  As magnet rolls used for these applications, those using sintered magnets have been known for a long time, but in recent years, synthetic resins or low-melting-point metals have been used from the viewpoint of ease of molding and shape flexibility. Magnet rolls produced by molding a magnetic material in which magnetic powder is blended with a binder are becoming mainstream. Such a magnet roll is conventionally produced by an injection molding method (for example, Japanese Patent Publication No. 63-41203) or an extrusion molding method (for example, Japanese Patent Laid-Open No. 55-165606).
[0003]
Normally, both ends of the magnet roll in the longitudinal direction require a shaft for rotating or fixing the magnet roll. Depending on how the shaft is formed, an injection molding method is used. The choice has been made between adopting an extrusion method. For example, an extrusion molding method is used for a cylindrical magnet body that penetrates a metal shaft, or a cylindrical magnet body that is processed at both ends to attach a metal short shaft, while the entire shaft including the shaft portion is used. The injection molding method is employed for integrally molding with a magnetic material containing magnetic powder.
[0004]
Since the magnet roll is long, when it is produced by an injection molding method, a mold (split mold) that is split in two in parallel to the longitudinal direction is used. For example, the manufacturing method includes a molding space b formed by abutting the fixed mold a1 and the movable mold a2 that are split in two along the axis of the target molded body M as shown in FIGS. The molten magnet material is filled and cooled and solidified in the mold (FIG. 15). After solidification, the mold is divided into two (FIG. 16), and a plurality of eject pins c, c,. And the magnet roll M is released from the mold and taken out (FIG. 17). Thereafter, the magnet roll is produced by repeating the cycle of closing the mold again and filling the next molten magnet material.
[0005]
[Problems to be solved by the invention]
However, this method has a problem that the productivity is low because the molded body must be sufficiently cooled before the molded body is taken out. If the cooling time is shortened in order to increase the productivity, the magnet roll will be insufficiently cured, and the warpage that occurs during ejection will increase, making it unusable as a magnet roll. Further, when the heating temperature of the mold is lowered in order to shorten the cooling time, there arises a problem that the surface property of the molded body is deteriorated or the filling property is deteriorated so that the moldability is deteriorated. For these reasons, it has been extremely difficult to increase the productivity of magnet rolls formed by injection molding.
[0006]
In addition, the mold has a parting surface p parallel to the longitudinal direction of the magnet roll, but when the molten magnet material is injected into the mold, the molten magnet material easily enters the parting surface, The parting surface exposed to the cavity (molding space) (edge on the cavity side of the parting surface) is scraped by high-hardness magnetic powder contained in the magnet material and is subject to wear and crushing easily. There is also a problem that is generally short.
[0007]
Furthermore, there is a problem that burrs are easily generated along the parting surface, which adversely affects the magnetic properties of the magnet roll.
Further, as a countermeasure against burrs, as shown in FIG. 18, a notch surface d called “meat stealing” is often provided at a portion where the parting surface p of the mold is present. When there exists, there exists a problem that arrangement | positioning of the excitation source in the metal mold | die provided corresponding to the magnetic pole of a magnet roll is restrict | limited. For example, in FIG. 18, magnetic materials e1, e2, e3, and e4 as excitation sources or magnetic paths exist around the forming space b with a nonmagnetic material f interposed therebetween, but the magnetic material e3 is indicated by a virtual line. Can't move on. As described above, the conventional mold has a problem that the magnetic pole cannot be set freely and the magnetic pole arrangement is limited.
[0008]
The present invention has been made in view of these problems, and suppresses the occurrence of warping of the magnet roll, shortens the molding cycle, and further increases the life of the mold, and the magnetic pole of the magnet roll. The present invention proposes a method of manufacturing a magnet roll and a manufacturing apparatus thereof that can increase the degree of freedom of arrangement.
[0009]
[Means for Solving the Problems]
  The present invention is to inject a predetermined amount of a magnetic material mixed with magnetic powder and a binder for binding and solidifying the magnetic powder into a mold for forming a target molded body, and reduce the diameter of the reduced diameter shaft to both ends of the columnar body. In a manufacturing method of an injection-molded magnet roll for molding a magnet roll having a shape protruding from a portion, a fixed mold that is a main mold for molding a portion including a substantially full length of a columnar body portion and one end side shaft portion of the molded body, Using a mold composed of a movable mold that is a sub mold for molding the remaining part including the other end side shaft portion of the molded body, the movable mold and the fixed mold are clamped to form a molding space, and the fixed The magnet material is injected into the molding space through a mold, the filled magnet material is cooled and cured, and when the mold is opened, the molded body is moved integrally with the movable mold, thereby removing the molded body from the fixed mold. Pull out in the longitudinal direction to release the mold, During or after the movement of the movable mold, the molded body is pushed out from the movable mold and released from the mold, and the diameter of the movable mold is reduced slightly toward the shaft end portion forming portion in the drawing direction of the molded body. A developing roll, a cleaning roll, and a transport roll in an electrophotographic developing device such as a copying machine, a facsimile machine, or a printer, characterized in that a mold is attached to the movable mold when a mold is opened. The manufacturing method of the injection-molded magnet roll used for is provided.
[0010]
  In addition, the present invention injects a predetermined amount of a magnetic material mixed with magnetic powder and a binder for binding and solidifying the magnetic powder into a mold for forming a target molded body, and reduces the diameter of both ends of the columnar body. In a method of manufacturing an injection-molded magnet roll for molding a magnet roll having a shape projecting from a shaft portion, a fixed die that is a main mold for molding a portion including the substantially full length of the columnar body portion and one end side shaft portion of the molded body, , Using a mold composed of a movable mold that is a sub mold for molding the remaining portion including the other end side shaft portion of the molded body, forming the molding space by clamping the movable mold and the fixed mold, A magnet material is injected into the molding space through a fixed mold, the filled magnet material is cooled and cured, and the molded body is moved integrally with the movable mold when the mold is opened. Is pulled out in the longitudinal direction to release the mold, During or after the movement of the movable mold, the molded body is pushed out from the movable mold and released from the mold, and the molded body is made to follow the movement of the movable mold on the inner surface of the movable end portion of the movable mold. A developing roll and a cleaning roll in an electrophotographic developing device such as a copying machine, a facsimile machine, a printer, etc., characterized in that a slight protrusion is provided and a molded body is attached to the movable mold when the mold is opened. A method for producing an injection-molded magnet roll used for a transport roll is also provided.
[0011]
  In these manufacturing methods, a magnetic circuit is built in the fixed mold, and the magnetic powder in the magnet material injected into the molding space can be magnetically oriented by the magnetic field generated by the magnetic circuit.
[0012]
  The present invention also provides an apparatus for manufacturing an injection-molded magnet roll for forming a magnet roll having a shape in which a reduced-diameter shaft portion protrudes from both ends of a columnar body. A fixed mold that is a main mold for molding a portion including a portion, a movable mold that is a sub mold for molding a remaining portion including a shaft portion on the other end side of the molded body, and a mold clamping and a mold Means for opening, means for injecting a magnetic material mixed with magnetic powder and a binder for binding and solidifying the magnetic powder into the molding space through a fixed mold, and means for cooling and hardening the magnet material filled in the molding space And an eject pin for removably moving the molded body from the movable mold by reciprocating in the longitudinal direction of the molded body with the tip facing the movable shaft end molding space, and the molded body is integrated with the movable mold when the mold is opened. By moving it from the fixed mold The shape is pulled out in the longitudinal direction and released, and during or after the movement of the movable mold, the molded body is pushed out from the movable mold by the eject pin and released from the mold. A developing roll, a cleaning roll, and a transport roll in an electrophotographic developing device such as a copying machine, a facsimile machine, and a printer, characterized by being given a reverse gradient that is slightly reduced in diameter in the drawing direction of the molded body An apparatus for producing an injection-molded magnet roll to be used is also provided.
[0013]
Furthermore, the present invention relates to an injection molded magnet roll manufacturing apparatus for molding a magnet roll having a shape in which a reduced diameter shaft portion is protruded from both ends of a columnar body. A fixed mold that is a main mold for molding a portion including a portion, a movable mold that is a sub mold for molding a remaining portion including a shaft portion on the other end side of the molded body, and a mold clamping and a mold Means for opening, means for injecting a magnetic material mixed with magnetic powder and a binder for binding and solidifying the magnetic powder into the molding space through a fixed mold, and means for cooling and hardening the magnet material filled in the molding space And an eject pin for removably moving the molded body from the movable mold by reciprocating in the longitudinal direction of the molded body with the tip facing the movable shaft end molding space, and the molded body is integrated with the movable mold when the mold is opened. By moving it from the fixed mold The shape is pulled out in the longitudinal direction and released from the mold. During or after the movement of the movable mold, the molded body is pushed out from the movable mold by the eject pin and released from the mold. A developing roll, a cleaning roll, and a transport in an electrophotographic developing device such as a copying machine, a facsimile machine, and a printer, characterized in that a small protrusion is provided to cause the molded body to follow the movement of the movable mold. An apparatus for producing an injection-molded magnet roll used for a roll is also provided.
[0014]
  Also in these manufacturing apparatuses, a magnetic circuit is built in the fixed mold, and the magnetic powder in the magnet material injected into the molding space can be magnetically oriented by the magnetic field generated by the magnetic circuit.
[0015]
  Moreover, the thing which suppressed the dispersion | variation in the longitudinal direction of the internal diameter dimension of shaping | molding space to 20 micrometers or less is desired.
[0016]
  Furthermore, the surface roughness of the inner surface of the molding space is R _max A value set to 1 S or less is preferable.
[0017]
  In particular, the inner surface of the molding space is preferably mirror-finished.
[0019]
[Action]
  In the production method of the present invention,A movable mold that is a fixed mold that is a main mold for molding a portion including the substantially full length of the columnar body portion of the molded body and the one end side shaft portion, and a sub mold for molding the remaining portion that includes the other end side shaft portion of the molded body. Using a mold composed of a mold, the movable mold and the fixed mold are clamped to form a molding space, the magnet material is injected into the molding space through the fixed mold, and the filled magnet material is cooled and hardened to form a mold. When opening, by moving the molded body integrally with the movable mold, the molded body is pulled out from the fixed mold in the longitudinal direction and released, and the molded body is removed from the movable mold during or after the movement of the movable mold. Extrude and release.
[0020]
When the magnetic circuit is built in the mold, a magnetic field is applied to the magnet material in the molten state, and the magnetic powder in the magnet material is oriented in a predetermined direction. The mold used in the present invention has no parting surface parallel to the longitudinal direction of the molded body unlike the conventional mold, and there is no notch surface for preventing burr generation, so the magnetic pole arrangement is limited. There is no.
[0021]
Roughness of the inner surface of the molding space is R_maxWhen the value is 1 S or less and the longitudinal variation of the inner diameter dimension of the molding space is 20 μm or less, the frictional resistance between the molded body and the cylindrical mold is kept low, and the molded body is separated from the cylindrical mold. The mold is easy, and the surface of the molded body taken out is smooth.
[0022]
In addition, if the end forming portion of the movable molded body is given a reverse gradient that is slightly reduced in diameter in the drawing direction of the molded body, or if a slight protrusion is provided on the inner surface of the end forming portion, this reverse The molded body follows the movement of the movable mold due to the catch by the gradient or the protrusion.
In the present invention, the molded body solidified in the mold is drawn out or pushed out in the longitudinal direction of the molded body, so that the molded body is released from the mold. Compared with the conventional injection molding method in which the molded body is released from the mold by pressing the molded body with a pin, the warpage of the molded body can be greatly reduced. Even when the molded body is not sufficiently cooled, the molded body can be taken out from the mold, so that the molding cycle can be greatly shortened.
[0023]
【Example】
  Examples illustrating the details of the present inventionReference examplesBased on Magnet roll targeted by the present inventionIsFor those used for developing rolls, cleaning rolls, transport rolls, etc. used in electrophotographic developing devices such as copying machines, facsimiles, printers, etc.Yes.
  The magnet material used in the present invention is a mixture of magnetic powder and a binder for binding and solidifying the magnetic powder. As the magnetic powder, ferrite-based, rare-earth-based (SmCo-based, NdFeB-based), MnAlC-based, alnico-based SmFeN-based materials can be selected, and as the binder, thermoplastic resins, thermosetting resins, low melting point alloys, and the like can be used.
[0024]
  FIG. 1 shows an example of a magnet roll produced by the production method of the present invention. As shown in FIG. 1, a magnet roll M (hereinafter also referred to as a molded body M) has a configuration in which shaft portions M2 and M3 having a reduced diameter are formed at both ends of a cylindrical main portion M1, and the whole is integrated by a magnet material. Molded. Examples belowReference examplesThen, this magnet roll will be described as an example, but the present invention isThe main part M1 is polygonal, etc.Applicable to other types of magnet rollsThe
[0025]
  2 to 5 arereference2 shows an outline of an example molding cycle. A mold for forming the magnet roll M is composed of a movable mold 1 and a fixed mold 2. The movable mold 1 is a cylindrical mold having a molding space 3a for molding a part including the substantially full length of the main part M1 of the molded body M and the one end side shaft part M2, and means that the molded body is molded with almost the entire length. It can be defined as the main mold. The movable mold 1 as the main mold is integrally formed by machining, and there is no parting surface on the inner peripheral surface of the molding space 3. Further, the longitudinal variation in the inner diameter dimension of the molding space is suppressed to 20 μm or less, and the surface roughness of the inner surface of the molding space is R_maxThe value is set to 1 S or less, and a mirror finish is applied as necessary. thisThe goldThis is because the molded product M is taken out from the mold by pulling out or extruding the molded product M in the longitudinal direction, so that it is necessary to reduce the frictional resistance between the molded product M and the inner surface of the mold. In order to facilitate removal of the molded body M from the mold, it is also preferable to form a draft at the inner surface portion of the mold corresponding to the position where the main portion M1 of the molded body M is formed.
[0026]
An eject pin 4 for extruding the molded body M is provided at a position adjacent to the position where the shaft portion M2 is formed on the movable mold 1 so as to be able to protrude into and out of the molding space 3a. The shaft portion M2 of the magnet roll M has a configuration in which a first shaft portion M21 and a second shaft portion M22 having different diameters are connected to each other. However, as shown in FIG. 6, corresponding to the movable mold 1 that forms the first shaft portion M21. A reverse gradient that slightly reduces the diameter in the drawing direction (right side in the drawing) of the molded body M is given to the location, and when the movable mold 1 is opened from the fixed mold 2, the molded body M is the movable mold 1. I try to keep up with the move. Although not shown, instead of providing a reverse gradient, a protrusion with a slight protrusion height may be formed on the inner surface of the corresponding portion of the movable mold 1 forming the first shaft portion M21.
[0027]
On the other hand, the fixed mold 2 is provided with a molding space 3b for molding the remaining other end side shaft portion M3 of the molded body M, and in the molding space 3 formed by joining the movable mold 1 and the fixed mold 2 to each other. A hot gate 5 for injecting molten magnet material is provided. The position where the hot gate 5 is provided is not limited to the illustrated example, and may be the outer peripheral position of the shaft portion M3.
[0028]
Manufacture of a magnet roll using a mold having such a configuration is performed in the following procedure.
A1) A cylindrical movable mold 1 and a fixed mold 2 are clamped to form a molding space 3, and a magnet material is injected into the molding space 3 and the filled magnet material is cooled and cured. (See Figure 2)
A2) While holding the molded body M integrally, the movable mold 1 is opened with respect to the fixed mold 2, and the shaft M3 is released from the fixed mold 2. (See Figure 3)
A3) The eject pin 4 is inserted into the molding space 3a from one end of the movable mold 1, the molded body M in the movable mold 1 is extruded in the longitudinal direction by a predetermined length, and the extruded molded body is a robot arm which is a gripping means. 6 to hold. (See Figure 4)
A4) The entire molded body M is released from the movable mold 1 by pulling the movable mold 1 from the molded body M to the left side in the figure while maintaining the gripping state of the molded body M by the robot arm 6. (See Figure 5)
Hereinafter, the magnet roll M is produced one after another by repeating the cycle of A1 to A4.
[0029]
  7 to 9 areRepresentative of the present inventionThe outline of the molding cycle of an example is shown. A mold for forming the magnet roll M is composed of a movable mold 11 and a fixed mold 12.BookExamples are described abovereferenceContrary to the example, the fixed mold 12 is a main mold, and the movable mold 11 is a sub mold.
  That is, the fixed mold 12 is a cylindrical mold having a molding space 13b for molding a part including the entire length of the main part M1 of the molded body M and the one end side shaft part M3, and the movable mold 1 and the fixed mold 2 are joined. A hot gate 15 for supplying molten magnet material is provided in the molding space 3 formed in this manner. The variation in the longitudinal direction of the inner diameter dimension of the molding space 13b is suppressed to 20 μm or less, and the surface roughness of the inner surface of the molding space 13b is set to 1S or less in R value, and the mirror finish is applied if necessary.referenceSimilar to the example.
[0030]
  On the other hand, the movable mold 11 has a configuration in which a molding space 13a for molding the remaining other-end side shaft portion M2 of the molded body M is provided, and is molded at a position adjacent to the shaft portion M2 formation position of the movable mold 11. An eject pin 14 for extruding the body M is provided in the molding space 13a so as to be able to appear and disappear.
  As shown in FIG. 10, the corresponding part of the movable mold 1 that forms the first shaft portion M <b> 21 includesreferenceSimilar to the example, a reverse gradient is given in which the diameter is slightly reduced in the drawing direction of the molded body M (right side in the figure). SaidreferenceIn the example, since the contact portion between the molded body M and the movable mold 1 has a relatively wide range, the molded body M and the movable mold 1 can be connected to each other without providing a reverse gradient at a location corresponding to the first shaft portion M21. Although it is possible to follow the mold opening operation of the movable mold 1 by the contact resistance,TypicalIn the case of the embodiment, since the contact portion between the movable mold 11 and the molded body M is only the shaft portion M2, the reverse gradient provided on the first shaft portion M21 is extremely important.
[0031]
Manufacture of a magnet roll using a mold having such a configuration is performed in the following procedure.
B1) The movable mold 11 and the cylindrical fixed mold 12 are clamped to form a molding space 13, and a magnet material is injected into the molding space 13 and the filled magnet material is cooled and cured. (See Figure 7)
B2) With the shaft M2 of the molded body M being held, the movable mold 11 is opened with respect to the fixed mold 12, and the entire length of the molded body M is pulled out from the fixed mold 12 in the longitudinal direction, and the molded body M is fixed. Release from 12. (See Figure 8)
A3) The eject pin 14 is inserted into the molding space 13 a from one end of the movable mold 11, and the shaft portion M <b> 2 held by the movable mold 11 is pushed out in the longitudinal direction to release from the movable mold 11. (See Figure 9)
[0032]
  in this wayreferenceExamplesTypicalIn the embodiment, the molded body M is released from the mold by extruding the molded body M cooled and hardened in the cylindrical mold in the longitudinal direction of the molded body M or pulling it out. Since there is no parting surface on the inner surface of the cylindrical mold, there is no partial wear on the inner surface of the mold and the mold life can be extended. Further, since the molded body M is taken out from the mold by being extruded or pulled out in the axial direction, the molded body M is hardly warped at the time of mold release.
[0033]
  Further, in the present invention, since a cylindrical mold having no parting surface on the inner peripheral surface is used, there is an advantage that there is no restriction on the arrangement of magnetic poles when performing magnetic field orientation molding. FIG. 11 shows the cross-sectional structure of the mold around the molding space when the magnetic circuit is built in the cylindrical mold. Here saidreferenceReference numerals corresponding to the examples are attached, and the magnetic circuit is built in the movable mold 1. Around the molding space 3, magnetic materials 7a, 7b, 7c. Serving as excitation paths such as permanent magnets and electromagnets and a magnetic path for magnetic flux generated from these sources. 7d is spaced apart with the nonmagnetic materials 8, 8. Since there are various functions required for the magnetic poles formed on the surface of the magnet roll, and the magnetic patterns thereof are also various, it is ideal that the magnetic poles can be arranged freely. As shown in FIG. 18, conventional molds for injection-molded magnet rolls have a parting surface p parallel to the longitudinal direction of the molded body, or a notch surface d called “meat stealing”. For this reason, the magnetic pole formation position is limited. However, in the present invention, as shown in FIG. 11, there is no parting surface in the mold for forming the main part M1 of the molded body M, so the magnetic pole arrangement is free. For example, it is optional to move the magnetic material 7c to the virtual line position.
[0034]
12 and 13 show cross-sectional views of a mold incorporating a magnetic circuit.
FIG. 12 shows an example when a permanent magnet is used as an excitation source, and FIG. 13 shows an example when an electromagnet is used as an excitation source. In FIG. 12, 20 is a molding space, 21 is a permanent magnet, 22 is a back yoke, 23 is a non-magnetic material part, and 24 is a cooling water channel. In FIG. 13, 30 is a molding space, 31 is a yoke, 32 is a coil, 33 is a back yoke, 34 is a nonmagnetic material portion, and 35 is a cooling water channel.
In the present invention, since there is no parting surface or notch surface for stealing meat on the inner surface of the mold, the arrangement positions of the permanent magnet 21 and the yoke 31 can be freely set, and the magnetic field pattern can be designed freely. Although not shown, an excitation source combining a permanent magnet and an electromagnet can also be used.
[0035]
Next, the results of a comparative test conducted by the present inventor for confirming the effect of the present invention will be described.

Magnet rolls were produced by the normal injection molding method and the injection molding method of the present invention under the above molding conditions, and the molding cycle time and the warpage of the finished molded body were measured. As shown in FIG. 14, the measurement of the warp supports both ends of the magnet roll M, the distance between the reference bar having no warp and the reference surface is d1, and the distance from the reference surface of the magnet roll M to be measured is d2. Then, the difference between these distances (d1−d2) was obtained, and this was set as the “size of warpage”. The results are shown in Table 1.
[0036]
[Table 1]

As shown in this table, according to the method of the present invention, a magnet roll with a small warp can be produced even if the molding cycle time is greatly shortened.
[0037]
"Comparison test 2: Relationship between cooling time and warpage"
Under the same conditions as in Comparative Test 1, the cooling time (total pressure holding, weighing, and cooling time) was changed to examine the warpage of the molded body. The results are shown in Table 2.
[0038]
[Table 2]

In Table 2, “deformation is extremely large” indicates that the portion pressed by the eject pin is deformed into a “<shape” shape and accurate measurement cannot be performed.
From Table 2, even if the magnet roll produced with the manufacturing method of this invention is short cooling time, the curvature amount is very small. Therefore, the cooling time can be greatly shortened as compared with the conventional injection molding method, and this table confirms that the present invention is extremely excellent in productivity. In the present invention, the warp of about 80 μm is presumed to be caused by a temperature non-uniformity during cooling and solidification in the cavity and a difference in thermal shrinkage inside the molded body.
Thus, in the present invention, the molded body solidified in the mold is drawn out or pushed out in the longitudinal direction of the molded body, so that the molded body is released from the mold, so that it is perpendicular to the longitudinal direction of the molded body. Compared with the conventional injection molding method in which the molded body is released from the mold by pushing the molded body with the eject pin from the direction, the warpage of the molded body can be greatly reduced. Even when the molded body is not sufficiently cooled, the molded body can be taken out from the mold without causing the molded body to be warped or in a state where the amount of warpage is suppressed within a practical range. As a result, the molding cycle can be greatly shortened.
[0039]
【The invention's effect】
The production method of the present invention is superior to the conventional injection molding method in the following points.
{Circle around (1)} Since the molded body is pulled out along the longitudinal direction of the molded body or is taken out from the mold by pushing it out, warpage at the time of mold release hardly occurs. In addition, since the cooling time of the molded body taken out from the mold can be greatly shortened as compared with the cooling time of the conventional injection molding method, the productivity can be dramatically improved.
(2) In the present invention, since a cylindrical mold having no parting surface is used on the inner peripheral surface of the cavity, the concentrated wear of the parting surface, which has been a problem of conventional injection molds, is eliminated. Mold life can be extended.
{Circle around (3)} Since there is no notch surface as a “thief” for preventing burrs on the inner surface of the cylindrical mold, there is no restriction on the magnetic pole arrangement, and the degree of freedom in designing the magnetic field pattern is increased.
[0040]
Roughness of the inner surface of the molding space is R_maxWhen the value is 1 S or less and the longitudinal variation of the inner diameter dimension of the molding space is 20 μm or less, the frictional resistance between the molded body and the cylindrical mold is kept low, and the molded body is separated from the cylindrical mold. The mold is easy, and the surface of the molded body taken out is smooth.
[0041]
In addition, the movable die end forming portion, which is the mold to be moved, is given a reverse gradient that is slightly reduced in diameter in the drawing direction of the molded body, or a slight protrusion is provided on the inner surface of the end forming portion. In this case, since the molded body follows the movement of the movable mold due to the reverse gradient and the catching by the protrusions, other special devices for making the molded body follow the movement of the movable mold become unnecessary.
[Brief description of the drawings]
FIG. 1 is a perspective view showing the appearance of a magnet roll.
FIG. 2 of the present inventionreferenceCross-sectional explanatory drawing showing the stage where the magnet material is injected and filled in the mold in the example
[Figure 3]referenceIn the example, a cross-sectional explanatory view showing a state in which the movable mold is opened with respect to the fixed mold while accompanying the molded body
[Figure 4]referenceIn the example, a cross-sectional explanatory view showing a state in which a molded body is extruded from a movable mold by an eject pin and this molded body is gripped by a robot arm.
[Figure 5] SamereferenceIn the example, a cross-sectional explanatory view showing a state in which the movable mold is taken from the molded body gripped by the robot arm
[Fig. 6]referenceCross-sectional explanatory drawing showing an example of giving a reverse gradient to the movable shaft end part in the example
[Fig. 7] of the present invention.TypicalSectional explanatory drawing which shows the step which carried out injection filling of the magnet material in the metal mold | die in an Example.
FIG. 8 is an explanatory cross-sectional view showing a state in which the movable mold is opened with respect to the fixed mold and the molded body is pulled out from the fixed mold with the molded body in the embodiment.
FIG. 9 is a cross-sectional explanatory view showing a state in which a molded body is extruded from a movable mold by an eject pin in the same embodiment
FIG. 10 is an explanatory cross-sectional view showing an example in which a reverse gradient is given to the movable shaft end portion in the embodiment.
FIG. 11 is a cross-sectional view showing a magnetic pole arrangement of a mold according to the present invention.
FIG. 12 is a cross-sectional view of a mold when a permanent magnet is used as an excitation source.
FIG. 13 is a cross sectional view of a mold when an electromagnet is used as an excitation source.
FIG. 14 is an explanatory diagram showing a comparative test method for warping of a magnet roll.
FIG. 15 is a cross-sectional explanatory view showing a stage in which a magnet material is injected and filled into a mold in a conventional injection molding method.
FIG. 16 is an explanatory cross-sectional view showing a state in which a mold is opened in a conventional injection molding method.
FIG. 17 is an explanatory cross-sectional view showing a state in which an eject pin is ejected and a molded body is taken out in a conventional injection molding method.
FIG. 18 is a cross-sectional view showing the magnetic pole arrangement of a conventional mold
[Explanation of symbols]
a1 Split type a2 Split type
M Magnet roll M1 Main part
M2 shaft M3 shaft
M21 1st shaft part M22 2nd shaft part
1 Movable type 2 Fixed type
3 Molding space
3a Molding space 3b Molding space
4 Eject pin 5 Hot gate
6 Robotic arm
7a, 7b, 7c, 7d Magnetic material 8 Non-magnetic material
11 Movable type 12 Fixed type
13 Molding space
13a molding space 13b molding space
14 Eject pin 15 Hot gate
20 Molding space 21 Permanent magnet
22 Back yoke 23 Non-magnetic
24 Cooling channel
30 Molding space 31 York
32 Coil 33 Back yoke
34 Non-magnetic material part 35 Cooling channel

Claims (9)

A predetermined amount of magnet material mixed with magnetic powder and a binder for binding and solidifying magnetic powder is injected into the mold to form the desired molded body, and reduced diameter shafts are provided at both ends of the columnar body. In the manufacturing method of the injection molded magnet roll for forming the magnet roll of the shape,
A movable mold that is a fixed mold that is a main mold for molding a portion including the substantially full length of the columnar body portion of the molded body and the one end side shaft portion, and a sub mold for molding the remaining portion that includes the other end side shaft portion of the molded body. Using a mold composed of molds,
A mold space is formed by clamping the movable mold and the fixed mold,
Injecting the magnet material into the molding space through the fixed mold, cooling and hardening the filled magnet material,
When the mold is opened, the molded body is moved integrally with the movable mold, so that the molded body is pulled out from the fixed mold in the longitudinal direction and released from the mold.
During or after the movement of the movable mold, the molded body is extruded from the movable mold and released .
The movable die shaft end forming portion is given a reverse gradient that is slightly reduced in diameter in the drawing direction of the molded body, and the molded body is attached to the movable mold when the mold is opened. to,
A method for producing an injection-molded magnet roll used for a developing roll, a cleaning roll, and a transport roll in an electrophotographic developing apparatus such as a copying machine, a facsimile machine, or a printer . A predetermined amount of magnet material mixed with magnetic powder and a binder for binding and solidifying magnetic powder is injected into the mold to form the desired molded body, and reduced diameter shafts are provided at both ends of the columnar body. In the manufacturing method of the injection molded magnet roll for forming the magnet roll of the shape,
A movable mold that is a fixed mold that is a main mold for molding a portion including the substantially full length of the columnar body portion of the molded body and the one end side shaft portion, and a sub mold for molding the remaining portion that includes the other end side shaft portion of the molded body. Using a mold composed of molds,
A mold space is formed by clamping the movable mold and the fixed mold,
Injecting the magnet material into the molding space through the fixed mold, cooling and hardening the filled magnet material,
When the mold is opened, the molded body is moved integrally with the movable mold, so that the molded body is pulled out from the fixed mold in the longitudinal direction and released from the mold.
During or after the movement of the movable mold, the molded body is extruded from the movable mold and released .
A slight protrusion is provided on the inner surface of the movable mold shaft end forming portion so that the molded body follows the movement of the movable mold, and the molded body is attached to the movable mold when the mold is opened. and,
A method for producing an injection-molded magnet roll used for a developing roll, a cleaning roll, and a transport roll in an electrophotographic developing apparatus such as a copying machine, a facsimile machine, or a printer . 3. An injection-molded magnet roll according to claim 1, wherein a magnetic circuit is built in the fixed mold, and magnetic powder in the magnet material injected into the molding space is magnetically oriented by a magnetic field generated by the magnetic circuit. Method. In an injection molding magnet roll manufacturing apparatus for molding a magnet roll having a shape in which a reduced-diameter shaft portion protrudes from both ends of a columnar body,
A fixed mold that is a main mold for molding a portion including the substantially full length of the columnar body portion of the molded body and the one end side shaft portion;
A movable mold that is a sub mold for molding the remaining portion including the other end side shaft portion of the molded body;
Means for clamping and opening the movable mold and the stationary mold;
Means for injecting a magnetic material mixed with a binder for binding and solidifying magnetic powder into the molding space through a fixed mold;
Means for cooling and hardening the magnet material filled in the molding space;
An eject pin that has a tip facing the movable mold shaft end molding space and reciprocates in the longitudinal direction of the molded body to release the molded body from the movable mold,
By moving the molded body integrally with the movable mold when the mold is opened, the molded body is pulled out from the fixed mold in the longitudinal direction and released, and during or after the movement of the movable mold, the eject pin Extruding the molded body from the movable mold and releasing it,
The movable type shaft end portion forming portion is provided with an inverse gradient that slightly decreases in diameter toward the drawing direction of the molded body,
An apparatus for manufacturing an injection-molded magnet roll used for a developing roll, a cleaning roll, and a transport roll in an electrophotographic developing apparatus such as a copying machine, a facsimile machine, or a printer . In an injection molding magnet roll manufacturing apparatus for molding a magnet roll having a shape in which a reduced-diameter shaft portion protrudes from both ends of a columnar body,
A fixed mold that is a main mold for molding a portion including the substantially full length of the columnar body portion of the molded body and the one end side shaft portion;
A movable mold that is a sub mold for molding the remaining portion including the other end side shaft portion of the molded body;
Means for clamping and opening the movable mold and the stationary mold;
Means for injecting a magnetic material mixed with a binder for binding and solidifying magnetic powder into the molding space through a fixed mold;
Means for cooling and hardening the magnet material filled in the molding space;
An eject pin that has a tip facing the movable mold shaft end molding space and reciprocates in the longitudinal direction of the molded body to release the molded body from the movable mold,
By moving the molded body integrally with the movable mold when the mold is opened, the molded body is pulled out from the fixed mold in the longitudinal direction and released, and during or after the movement of the movable mold, the eject pin Extruding the molded body from the movable mold and releasing it,
A slight protrusion for causing the molded body to follow the movement of the movable mold is provided on the inner surface of the movable mold shaft end forming portion,
An apparatus for manufacturing an injection-molded magnet roll used for a developing roll, a cleaning roll, and a transport roll in an electrophotographic developing apparatus such as a copying machine, a facsimile machine, or a printer . 6. The injection molded magnet roll according to claim 4 or 5, wherein a magnetic circuit is built in the fixed mold, and magnetic powder in the magnet material injected into the molding space is magnetically oriented by a magnetic field generated by the magnetic circuit. apparatus. The manufacturing apparatus for an injection-molded magnet roll according to any one of claims 4 to 6 , wherein variation in the longitudinal direction of the inner diameter dimension of the molding space is suppressed to 20 µm or less. The apparatus for producing an injection-molded magnet roll according to any one of claims 4 to 7 , wherein the surface roughness of the inner surface of the molding space is set to R _max value of 1S or less. The apparatus for producing an injection-molded magnet roll according to any one of claims 4 to 8 , wherein the inner surface of the molding space is mirror-finished.

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