JP2006289970A - Method for manufacturing magnet block and its die - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a magnet block capable of suppressing the occurrence of air bubbles, and a die for use in the method. <P>SOLUTION: The die 36 provided with an upper die 42, to which a recessed part 46 is formed, and a lower die 44, to which a recessed part 48 is formed, is used for the method for manufacturing the magnet block 20. Notched parts 50A, 50B are formed to the lower die 44 of the die 36 along the edge parts 48a, 48b of the recessed part 48. When a cavity C is formed by fitting the upper die 42 and the lower die 44 to each other, groove parts 52A, 52B externally extended along a parting face S from the cavity C are formed by the notched parts 50A, 50B. When a molten resin 54 is injected and filled into the cavity C to which such groove parts 52A, 52B are formed, air in the cavity C can easily escape from the parting face S part to the outside of the die 36 by flowing in the directions of the groove parts 52A, 52B. Consequently, it is possible to obtain the magnet block 20 in which the occurrence of the air bubbles is suppressed. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method of manufacturing a magnet block that constitutes a magnet roll used in an electrophotographic developing device such as a copying machine, a facsimile machine, and a printer, and a mold thereof.

  Conventionally, the metal mold | die used for a magnet roll is disclosed by the following patent document 1 and patent document 2, for example. These publications show a pair of upper and lower molds having mold holes extending parallel to the longitudinal direction of the magnet roll to be molded.

  In addition, since the magnet roll is required to have a plurality of functions such as developer transport, development, and peeling, it is necessary to form a plurality of magnetic poles in the circumferential direction. Therefore, apart from the integrally formed magnet roll described above, a magnet roll in which a plurality of magnet blocks are attached to a shaft is disclosed in Patent Document 3 below.

  Then, in order to produce this magnet block by injection molding, the inventors formed the lower mold 104 that forms the inner peripheral curved surface and both side planes of the magnet block and the outer peripheral curved surface of the magnet block as shown in FIG. A mold 100 composed of the mold 102 was made as a prototype.

  Here, since the magnet block is a long body whose length is extremely longer than the cross-sectional dimension, it is very important to have a stable magnetic characteristic in the longitudinal direction. However, when a magnet block is manufactured using the mold, the magnetic characteristics in the longitudinal direction of the magnet block may be locally deteriorated. Further, in a magnet block in which such a local decrease (drop) in magnetic characteristics has occurred, there is a case where unevenness of image density is caused when used in a copying machine or the like.

The reason why the magnetic properties are reduced in this way is that bubbles are generated in the magnet block as a result of mixing the molten resin and the air in the cavity when the molten resin is injected and filled into the cavity. Conceivable. Therefore, a gas vent is provided at the other end in the longitudinal direction of the mold so as to face the gate opening provided at one end in the longitudinal direction of the mold, so that the molten resin injected from the gate port can be smoothly discharged. By reaching to the back, the situation where the molten resin and the air in the cavity were mixed with each other was suppressed.
Japanese Patent Laid-Open No. 11-77783 JP-A-11-170291 Japanese Patent Laid-Open No. 11-150017

  However, even if such a degassing portion is provided, the generation of bubbles cannot be sufficiently suppressed, and as a result, the local drop in magnetic properties in the longitudinal direction of the magnet block has not been improved. Thus, the inventors have intensively researched and found a new technology that can further suppress the generation of bubbles in the magnet block.

  That is, an object of the present invention is to provide a method for manufacturing a magnet block in which the generation of bubbles is suppressed, and a mold thereof.

  The method for manufacturing a magnet block according to the present invention is used to manufacture a magnet block of a magnet roll having a shaft and a plurality of magnet blocks, and includes a first recess extending along the longitudinal direction of the manufactured magnet block. A first mold that forms an outer peripheral curved surface of the magnet block by the first recess, and a second recess that extends along the longitudinal direction of the magnet block to be manufactured. A second die that forms the inner curved surface and both side surfaces of the magnet block by the edge, the edge parallel to the longitudinal direction of the first recess of the edges of the first recess, and , At least one of the edges of the second recesses parallel to the longitudinal direction of the second recesses is separated from the cavity formed by the first and second recesses. A method of manufacturing a magnet block using a mold in which a notch that forms a groove extending outward along the wing surface is formed along the edge, wherein the first mold and the second mold And a step of forming a cavity by injection, filling a cavity with a molten resin containing magnetic powder, and solidifying the molten resin injected and filled into the cavity.

  In this magnet block manufacturing method, a mold including a first mold in which a first recess is formed and a second mold in which a second recess is formed is used. Of the edge of the first recess, the edge parallel to the longitudinal direction of the first recess and the edge of the second mold edge parallel to the longitudinal direction of the second recess At least one of them has a notch along the edge. When the cavity is formed by combining the first mold and the second mold, a groove that extends outward from the cavity along the parting surface is formed by the notch. The inventors have intensively researched that when the molten resin is injected and filled into the cavity in which such a groove is formed, the air in the cavity flows in the direction of the groove and easily escapes from the parting surface portion to the outside of the mold. I found it at the end. Therefore, the situation where the molten resin and the air in the cavity are mixed is suppressed. As a result, the generation of bubbles is suppressed in the molded product obtained by solidifying the molten resin injected and filled in the cavity.

  Moreover, you may further provide the step of removing the part corresponding to the groove part of the molded article obtained by solidification of molten resin. When the molten resin enters the part corresponding to the groove part, the part corresponding to the groove part of the molded product is removed.

  Moreover, the notch part may be formed over the substantially full length of the edge part. In this case, a long groove is obtained, and as a result, the effect of suppressing bubbles is obtained over substantially the entire length of the edge.

  Moreover, the notch part may be partially formed along the edge part, and may extend from the opposite side to the side by which the molten resin is injection-filled. Even if it is such a notch part, the bubble suppression effect equivalent to the notch part formed over the full length of the edge part can be acquired.

  Further, the width of the cutout portion at the first position may be wider than the width at the second position on the side where the molten resin is injected and filled from the first position.

  Moreover, the notch part may contain the part which the width | variety increases gradually toward the opposite side from the side in which molten resin is injection-filled.

  Moreover, it is preferable that the depth is substantially uniform about the direction which goes outside from a cavity. In this case, since the shape of the notch part which forms a groove part becomes simple, manufacture of a metal mold | die becomes easy.

  Moreover, it is preferable that the groove depth is gradually increased or gradually decreased with respect to the outward direction from the cavity.

  Moreover, it is preferable that the groove depth is 0.1 mm or less.

  Moreover, it is preferable that a groove part has a 1st groove part adjacent to a cavity, and a 2nd groove part deeper than a 1st groove part while being located outside rather than a 1st groove part.

  Moreover, it is preferable that the depths of the first and second groove portions are substantially uniform with respect to the outward direction from the cavity. In this case, since the shape of the notch part which forms a groove part becomes simple, manufacture of a metal mold | die becomes easy.

  Moreover, it is preferable that the groove depth of at least one of the first and second groove portions is gradually increased or gradually decreased with respect to the outward direction from the cavity.

  The first groove portion preferably has a groove depth of 0.05 mm or less, and the second groove portion preferably has a width in the range of 0.02 mm to 1 mm.

  A magnet block mold according to the present invention is used to manufacture a magnet block of a magnet roll having a shaft and a plurality of magnet blocks, and has a first recess extending along the longitudinal direction of the manufactured magnet block. A first mold that forms an outer peripheral curved surface of the magnet block by the first recess, and a second recess that extends along the longitudinal direction of the magnet block to be manufactured. And a second die that forms the inner curved surface and both side surfaces of the magnet block, and an edge parallel to the longitudinal direction of the first recess of the edges of the first recess, and a second die At least one of the edges parallel to the longitudinal direction of the second recess is removed from the cavity formed by the first and second recesses along the parting surface. Notches forming the groove extending, characterized in that it is formed along the edge.

  The magnet block mold includes a first mold in which a first recess is formed and a second mold in which a second recess is formed. Of the edge of the first recess, the edge parallel to the longitudinal direction of the first recess and the edge of the second mold edge parallel to the longitudinal direction of the second recess At least one of them has a notch along the edge. When the cavity is formed by combining the first mold and the second mold, a groove that extends outward from the cavity along the parting surface is formed by the notch. The inventors have intensively researched that when the molten resin is injected and filled into the cavity in which such a groove is formed, the air in the cavity flows in the direction of the groove and easily escapes from the parting surface portion to the outside of the mold. I found it at the end. Therefore, the situation where the molten resin and the air in the cavity are mixed is suppressed. Therefore, in the magnet block obtained by solidifying the molten resin, the generation of bubbles is significantly suppressed.

  Moreover, the notch part may be formed over the substantially full length of the edge part. In this case, a long groove is obtained, and as a result, the effect of suppressing bubbles is obtained over substantially the entire length of the edge.

  Moreover, the notch part may be partially formed along the edge part, and may extend from the opposite side to the side by which the molten resin is injection-filled. Even if it is such a notch part, the bubble suppression effect equivalent to the notch part formed over the full length of the edge part can be acquired.

  Further, the width of the cutout portion at the first position may be wider than the width at the second position on the side where the molten resin is injected and filled from the first position.

  Moreover, the notch part may contain the part which the width | variety increases gradually toward the opposite side from the side in which molten resin is injection-filled.

  Moreover, it is preferable that the groove depth is substantially uniform in the direction from the cavity toward the outside. In this case, since the shape of the notch part which forms a groove part becomes simple, manufacture of a metal mold | die becomes easy.

  Moreover, it is preferable that the groove depth is gradually increased or gradually decreased with respect to the outward direction from the cavity.

  Moreover, it is preferable that the depth of a groove part is 0.1 mm or less.

  Moreover, it is preferable that a groove part has a 1st groove part adjacent to a cavity, and a 2nd groove part deeper than a 1st groove part while being located outside rather than a 1st groove part.

  Moreover, it is preferable that the groove depths of the first and second groove portions are substantially uniform with respect to the outward direction from the cavity. In this case, since the shape of the notch part which forms a groove part becomes simple, manufacture of a metal mold | die becomes easy.

  Moreover, it is preferable that the groove depth of at least one of the first and second groove portions is gradually increased or gradually decreased with respect to the outward direction from the cavity.

  The first groove portion preferably has a groove depth of 0.05 mm or less, and the second groove portion preferably has a groove depth in the range of 0.02 mm to 0.1 mm.

  ADVANTAGE OF THE INVENTION According to this invention, the manufacturing method of a magnet block with which generation | occurrence | production of a bubble is suppressed and its metal mold | die are provided.

  Embodiments of a magnet block manufacturing method and its mold according to the present invention will be described below in detail with reference to the accompanying drawings. In addition, the same code | symbol is attached | subjected about the same or equivalent element, and the description is abbreviate | omitted when description overlaps. In addition, the present invention is not limited to the following embodiment, and is merely an embodiment.

  FIG. 1 is a schematic perspective view of a developing roll 10 according to an embodiment of the present invention, and FIGS. 2 and 3 are a sectional view taken along line II-II and a sectional view taken along line III-III, respectively, of the developing roll 10 shown in FIG. FIG.

  As shown in FIGS. 1 to 3, the developing roll 10 includes a long cylindrical metal sleeve 12, a magnet roll 14 disposed inside the sleeve 12, and end openings 12 a and 12 b of the sleeve 12. It is comprised with a pair of flange 16A, 16B fixed by fitting.

  Furthermore, the magnet roll 14 is composed of a round bar-shaped shaft 18 made of a high-strength material such as metal, and five long magnet blocks 20 (20A to 20E) fixed to the outer peripheral surface 18a of the shaft 18. It is configured.

Each magnet block 20 is a plastic magnet or rubber magnet composed of magnetic powder (ferrite-based or Nd-Fe-B-based) and resin (rubber-based or plastic-based). The sectional shape of each magnet block 20, as shown in FIG. 3, the first and arc A _1, the first arc A ₁ and same curvature having substantially the same curvature as the outer peripheral surface 18a of the shaft 18 second and arc a ₂ is larger curvature radius than the first arc a ₁ has a central and opening angle, straight line connecting the first corresponding end points of the arc a ₁ and the second arc a ₂ 2 The shape is formed by the line segments L ₁ and L ₂ . A curved surface in which the first arc A ₁ extends in the longitudinal direction of the magnet block 20 is an inner peripheral curved surface 20 a of the magnet block 20, and the second arc A ₂ also extends in the longitudinal direction of the magnet block 20. The curved surface is the outer peripheral curved surface 20b of the magnet block 20, and a pair of planes in which the _two line segments L ₁ and L ₂ extend in the longitudinal direction of the magnet block 20 are both side planes 20c and 20d of the magnet block 20. It has become.

And each magnet block 20 is being fixed to the outer peripheral surface 18a of the shaft 18 with the adhesive agent which is not shown in figure in the inner peripheral curved surface 20a. Incidentally, both the first opening angle of the arc A ₁ of each magnet block 20 cross section also has a 60-degree, five magnet block 20A~20E is fixed so as to be adjacent to each other. That is, the shaft 18 is not completely surrounded by the magnet block 20, and the block missing portion 22 where the magnet block 20 does not exist is formed around the shaft 18. Note that the polarities of the magnet blocks 20A to 20E on the outer peripheral curved surface 20b are arranged such that the N poles and the S poles are alternated as indicated by the reference signs N and S in FIG.

  A gap having a predetermined distance d is formed between the outer peripheral surface 14 a of the magnet roll 14 formed by the outer peripheral curved surface 20 b of the magnet block 20 and the inner peripheral surface 12 c of the sleeve 12.

In addition, the shape and magnetic force of each magnet block 20 can be appropriately changed according to the required magnetic flux density and magnetization pattern. For example, with respect to the shape of the magnet block 20, the first opening angle of the arc A ₁ of the cross section of the magnet block 20 is not limited to 60 degrees, can be increased or decreased for each magnet block as required.

  The magnet roll 14 described above is disposed in the sleeve 12 and is rotatably supported by a pair of flanges 16A and 16B located at both ends of the sleeve 12. Here, the flange 16A and the flange 16B are formed with holes 24A and 24B, respectively, along the central axis thereof. Bearings 26A and 26B (rotatingly supporting the shaft 18 are provided inside the holes 24A and 24B, respectively. For example, a sintered oil-impregnated bearing is attached.

  When the developing roll 10 is installed in the developing device, the magnet roll 14 is held so as not to rotate, and only the case 28 covering the magnet roll 14 is held rotatably around the shaft 18. In this state, a gear or the like is attached to the shaft portion 30 of the flange 16B, and the shaft portion 30 is rotationally driven by a motor or the like, whereby the rotation control of the case 28 of the developing roll 10 is performed.

  Next, a method for producing the magnet block 20 described above will be described with reference to FIGS. Here, FIG. 4 is a schematic plan view showing a mold used when manufacturing the above-described magnet block 20, and FIG. 5 is a cross-sectional view taken along the line α-α of the mold shown in FIG. FIG. 6 is a diagram showing a procedure for manufacturing the magnet block 20 using the mold shown in FIGS. 4 and 5.

  As shown in FIG. 4, the metal mold 36 used for manufacturing the magnet block 20 is opposed to the gate member G and the gate member 38 through which the gate port G along the extending direction of the magnet block 20 is formed. The iron block 40 is disposed at a position, and an upper die (first die) 42 and a lower die (second die) 44 interposed between the gate member 38 and the iron block 40. As shown in FIG. 5, the sectional shape of the cavity C formed by the upper mold 42 and the lower mold 44 substantially corresponds to the sectional shape of the magnet block 20.

  A concave portion (first concave portion) 46 corresponding to the outer peripheral curved surface 20b of the magnet block 20 described above is formed on the lower surface 42a of the upper mold 42 in the longitudinal direction of the magnet block 20 to be produced (X direction in FIGS. 4 and 5). It is formed along. On the other hand, on the upper surface 44a of the lower mold 44, a concave portion (second concave portion) 48 corresponding to the inner peripheral curved surface 20a of the magnet block 20 and the both side planes 20c and 20d is provided in the longitudinal direction of the magnet block 20 that is also produced. It is formed along.

Of the edges of the recess 48 of the lower mold 44, the notches 50A and 50B are respectively provided on both edges 48a and 48b parallel to the longitudinal direction of the recess 48 (X direction in FIGS. 4 and 5). edge 48a, over the entire length of the 48b are formed with a uniform width _{W 1.} The groove width is preferably 2 mm or more and 20 mm or less, for example. This is because if the groove width is less than 2 mm, bubbles may not be sufficiently removed and bubbles may be mixed into the molded product. On the other hand, when the groove width exceeds 20 mm, no further improvement in bubble removal can be obtained. The notches 50A and 50B allow the cavity C to have a parting surface S (a mating surface between the upper die 42 and the lower die 44, which is parallel to the XY plane in FIGS. 4 and 5). ) Are formed over the entire length of the cavity C from the cavity C to the outside of the mold. Double-pole-away portion 50A, 50B are both formed from the cavity C as the groove 52A in the direction toward the outward (Y direction in FIG. 4 and FIG. 5), the groove depth of 52B becomes uniform depth D ₁ ing. That is, the depth _{D 1} of the from the upper surface 44a of the notch 50A, 50B of the lower die 44 are the same at any position in the Y direction. Since the notches 50A and 50B having such a cross-sectional shape are simple in shape, the lower mold 44 can be easily manufactured.

  Next, a procedure for manufacturing the magnet block 20 using the mold 36 described above will be described. When the magnet block 20 is manufactured, as shown in FIG. 6A, the upper mold 42 and the lower mold 44 are arranged so that the lower surface 42a of the upper mold 42 and the upper surface 44a of the lower mold 44 face each other. At the same time, the lower surface 42a of the upper mold 42 and the upper surface 44a of the lower mold 44 are fixed to each other so that the cavity C is formed.

  Then, as shown in FIG. 6B, the cavity C is filled with a molten resin 54, which is a raw material of the magnet block 20, from a gate port G provided at a substantially central portion of the cavity C cross section. Thereafter, a predetermined pressure holding process and a cooling process are performed to solidify the molten resin 54 to form a resin molded product 56 to be the magnet roll 20 as shown in FIG. At this time, the outer peripheral curved surface 20 b of the magnet block 20 is formed by the concave portion 46 of the upper mold 42, and the inner peripheral curved surface 20 a and the both side planes 20 c and 20 d of the magnet block 20 are formed by the concave portion 48 of the lower mold 44. If the eaves portions 58A and 58B of the resin molded product 56 corresponding to the grooves 52A and 52B of the cavity C are formed, they are removed by cutting or polishing. The manufacture of the magnet block 20 is completed by the above procedure. The magnet block 20 thus obtained is attached to the shaft 18 after magnetizing a predetermined magnetic pole on the outer peripheral curved surface 20b. In addition, you may make it the aspect which applies a magnetic field to the molten resin injection-filled in the cavity C suitably.

  Then, when the magnet block 20 is manufactured using the mold 36 by the method as described above, the upper mold 102 in which the concave portion 106 corresponding to the outer peripheral curved surface 20b of the magnet block 20 is formed as shown in FIG. In the case of using the conventional mold 100 that is formed of the inner peripheral curved surface 20a of the block 20 and the lower mold 104 formed with the concave portions 108 that form both side planes 20c and 20d and that forms the cavity C without the groove portions 52A and 52B. The inventors have newly found that bubbles are less likely to be generated in the magnet block 20.

  This is because, in the manufacturing process of the magnet block 20 described above, when the molten resin 54 is injected and filled into the cavity C, the molten resin 54 is used when compared with the case where the metal mold 100 is used. It is considered that this is because the air that was in the cavity C when injection-filling 54 is easy to escape from the parting surface S portion to the outside of the mold 36. More specifically, in the mold 36, the molten resin 54 injected from the gate port G causes the air in the cavity C to flow out of the gas vent F (the contact surface portion between the upper mold 42 and the lower mold 44 and the iron block 40. In addition, a part of the air also flows in the direction of the grooves 52A and 52B and flows out of the mold through the parting surface S from the grooves 52A and 52B due to the injection pressure of the molten resin 54. It is thought that it is to do. And since such groove part 52A, 52B is formed over the full length of the cavity C, since a long groove part is obtained and it is easy to escape air from any position regarding the longitudinal direction of the cavity C. The effect of suppressing bubbles is obtained over the entire length of the magnet block 20.

  On the other hand, in the conventional mold 100, since the groove portion described above is not formed in the cavity C, most of the air in the cavity C escapes from the gas vent F when the molten resin is injected and filled. Some of them are entrained in the molten resin and become air bubbles and remain in the molded product. As a result, the molten resin 54 introduced into the cavity C is likely to contain air that affects the magnetic characteristics of the developing roller 10.

  As described in detail above, when the mold 36 according to the present embodiment is used, a situation in which the molten resin 54 and the air in the cavity C are mixed with each other is suppressed, and as a result, the melt injected and filled into the cavity C is suppressed. In the molded product 56 obtained by solidifying the resin 54, the generation of bubbles is suppressed. Accordingly, the generation of bubbles is also suppressed in the magnet block 20 using the molded product 56. In addition, in the magnet block 20 in which the generation of bubbles is suppressed in this way, improvement in uniformity of magnetic characteristics and suppression of reduction in mechanical strength are realized.

Above the groove 52A, the groove depth _{D 1} of the 52B is preferably at 0.1mm or less, and even more preferably within the range of 0.03Mm～0.08Mm. Here, the groove depth _{D 1} is more than 0.1mm the visor portion 58A, the thickness of 58B becomes too thick, the workability of the removal is poor. Note that by design as the groove depth D ₁ is 0.05mm or less, the molded article 56 as described above, since the situation in which the eave portion 58A, 58B is suppressed from occurring significantly, the removal process is omitted, The manufacturing efficiency of the magnet block 20 is greatly improved.

In addition, the metal mold | die 36 demonstrated above can also be suitably changed into the metal mold | die 36A shown in FIG. 7, and the metal mold | die 36B shown in FIG. That is, in the mold 36A, double-pole-away portion 50A of the lower mold 44, 50B are both groove 52A in the direction toward the outward from the cavity C (Y direction in FIG. 7), the groove depth _{D 1} of the 52B gradually It is formed to increase. In the mold 36B, double-pole-away portion 50A of the lower mold 44, 50B are both groove 52A in the direction toward the outward from the cavity C (Y direction in FIG. 8), the depth _{D 1} of the 52B gradually decreases It is formed to do. Even if the magnet block 20 is manufactured using the mold 36A and the mold 36B, the same or equivalent effect as the above-described mold 36 can be obtained. In this case, the grooves 52A, 52B groove depth _{D 1} of the is preferably 0.1mm or less, and even more preferably within the range of 0.03Mm～0.08Mm.

  Next, a mold 60 having a different form from the mold 36 described above will be described with reference to FIG.

  The mold 60 shown in FIG. 9 is different from the above-described mold 36 in the cross-sectional shape of the groove portion, and the other portions are the same or equivalent. That is, in the mold 60, similarly to the mold 36, a recess (first recess) 66 corresponding to the outer peripheral curved surface 20 b of the magnet block 20 is formed on the lower surface 62 a of the upper mold (first mold) 62. The magnet block 20 is formed so as to extend along the longitudinal direction (X direction in FIG. 9). The upper surface 64a of the lower mold (second mold) 64 has an inner circumferential curved surface 20a and both side planes. Recesses (second recesses) 68 corresponding to 20c and 20d are formed along the longitudinal direction of the magnet block 20 that is also produced.

  Of the edges of the recess 68 of the lower mold 64, the notches 70A and 70B are respectively provided on the edges 68a and 68b parallel to the longitudinal direction of the recess 68 (X direction in FIG. 9). , 68b is formed over the entire length. The notches 70A and 70B allow the cavity C to enter the parting surface S of the mold 60 (the mating surface of the upper mold 62 and the lower mold 64 parallel to the XY plane in FIG. 9). Grooves 72A and 72B extending from the cavity C to the outside of the mold are formed over the entire length of the cavity C.

Each groove 72A, 72B has a first groove 72a groove depth adjacent the cavity C is _{D 2,} the groove depth is located outward from the first groove 72a is _D 3 (> _{D 2} ) Second groove portion 72b. Therefore, the corresponding notches 70A, for even 70B, the first notch portion 70a and the depth from the upper surface 44a of the lower mold 44 is _{D 3} depth from the upper surface 44a of the lower die 44 is _{D 2} And a second cutout portion 70b.

  In the mold 60 having such groove portions 72A and 72B, in addition to the effects similar to those of the mold 36 described above, when the eaves portion is generated in the molded product 56, the eaves portion can be easily removed. Can be done. That is, in the eaves portion of the molded product 56, the eaves portion corresponding to the first groove portion 72a (the base portion) is significantly reduced in thickness, so that the eave portion attached to the magnet block 20 can be easily formed. Can be removed. In addition, if such a groove part is the cross-sectional shape which can make the base part of an eaves part thin, it does not necessarily need to be the groove part of the 2 step | paragraph structure mentioned above, and it changes into the groove part of a multistage structure as needed May be.

Groove depth _{D 2} of the first groove portion 72a described above is preferably 0.05mm or less. Here, the groove depth D ₂ is greater than 0.05 mm, the thickness of the eaves portion becomes thicker, meaning that the two-stage configuration wanes. Because on the contrary, by designing such groove depth D ₁ is 0.05mm or less, the molded article 56 as described above, a situation in which eaves occurs is significantly suppressed, the removal process is omitted, The manufacturing efficiency of the magnet block 20 is greatly improved. The first groove 72a, since it flowed gas by the distance to the second groove 72b, the groove depth D ₂ is required for flowing the gas to the mold outside along the parting surface S groove 52A of a one-stage configuration, it is possible to design narrower than the groove depth D ₁ of the 52B. Incidentally, the groove depth _{D 3} of the second groove 72b is preferably in the range of 0.02Mm～1mm.

In addition, the metal mold | die 60 demonstrated above can also be suitably changed into the metal mold | die 60A shown in FIG. That is, in the mold 60A, double-pole-away portion 70A of the lower mold 64, both 70B, the groove depth _{D 3} of the groove depth _{D 2} and the second groove 72b of the first groove portion 72a is out of the cavity C It is formed so as to gradually increase in the direction toward the direction (Y direction in FIG. 10). Even if the magnet block 20 is produced using the mold 60A, the same or equivalent effect as that of the mold 60 described above can be obtained. Further, an aspect in which only one of the first groove portion 72a and the second groove portion 72b is gradually increased, the groove width of both the first groove portion 72a and the second groove portion 72b, or either one of them. Even in an aspect in which the groove width gradually decreases, an effect similar to or equivalent to that of the mold 60 described above can be obtained.

  Moreover, in the metal mold | die demonstrated above, as shown in the top view of FIG. 4, only the aspect in which the notch part was formed by uniform width over the full length of the edge parts 48a and 48b of the recessed part 48 is shown. However, the notch is not limited to such an aspect, and may be an aspect as shown below.

The mold 75 shown in FIG. 15 is different only in the lengths of the above-described mold 36 and the lower mold, and the other parts are the same or equivalent. That is, in this mold 75, the notches 78A and 78B of the lower mold 77 are partially formed from the end surface 77b of the lower mold 77 on the gas venting section F side (that is, the side opposite to the side where the molten resin is injected and filled). Extended. More specifically, both edge portions 48a and 48b of the recess 48 of the lower mold 77 are notched from the end surface 77b of the lower mold 77 to a position H of the length L _B (<length L _A of the lower mold 77). The portions 78A and 78B are formed, and the notch portion is not formed from the position H to the end surface 77a on the gate port G side (that is, the side where the molten resin is injected and filled). Notches 78A, the width of the 78B is notched portions 50A, and has a uniform width _{W 1} as with 50B. The depth of the groove formed by the notches 78A and 78B is uniform in the direction outward from the cavity C (Y direction in FIG. 15), gradually increasing or decreasing, and two steps. Any of the configuration modes may be used (see FIGS. 5 and 7 to 10).

  Even with these notches 78A and 78B, it is possible to obtain the same bubble suppression effect as the notches 50A and 50B described above. That is, even if it is a groove part partially formed in the above-mentioned cavity C, the same effect is acquired by arrange | positioning the groove part to the degassing part F side. This is presumably because the air inside the cavity C flows to the gas vent F side during resin injection and is smoothly discharged outside the mold by the groove provided in that portion. Further, since the volume of the groove formed by the notches 78A and 78B is reduced compared to the case of the notches 50A and 50B, the amount of molten resin necessary for filling is reduced, Costs are being reduced. In addition, since the eaves portion of the molded product generated in the groove portion formed by the notches 78A and 78B is smaller than the case of the notches 50A and 50B, the labor and time required to remove the eaves are significant. Reduced to Further, when the cutout portion is formed in the mold by cutting, the cutout portions 78A and 78B have a shorter cutting length than the cutout portions 50A and 50B. Significantly reduced. In this embodiment as well, by designing the groove depth to be 0.05 mm or less, a situation in which the eaves portion is generated in the molded product is significantly suppressed, and the manufacturing efficiency of the magnet block 20 can be drastically improved.

In addition, the mold 80 shown in FIG. 16 is different in the shape of the above-described mold 36 and the lower mold, and the other parts are the same or equivalent. That is, the mold 80 has a width W on both edges 48a and 48b of the recess 48 of the lower mold 82, from the end surface 82a on the gate port G side of the lower mold 82 toward the end surface 82b on the gas vent F side. Cutout portions 83A and 83B in which ₂ gradually increases are formed. More specifically, notches 83A, the width _{W 2} at an arbitrary position _{P 1} (first position) of 83B is positioned _{P 2} is from its position _{P 1} to the gate port G side (second position) It is wider than the width W ₂ in. The depth of the groove formed by the notches 83A and 83B is uniform in the direction outward from the cavity C (Y direction in FIG. 16), gradually increasing or decreasing, and two steps. Any of the configuration modes may be used (see FIGS. 5 and 7 to 10).

  Even with these notches 83A and 83B, the same bubble suppression effect as that of the notches 50A and 50B described above can be obtained. Further, similarly to the notches 78A and 78B, the volume of the groove to be formed can be reduced, so that the amount of molten resin required for filling can be reduced also in the notches 83A and 83B. Furthermore, since the eaves portion of the molded product generated in the groove portion formed by the notches 83A and 83B can be reduced, labor and time required for removing the eaves portion are significantly reduced. In this embodiment as well, by designing the groove depth to be 0.05 mm or less, a situation in which the eaves portion is generated in the molded product is significantly suppressed, and the manufacturing efficiency of the magnet block 20 can be drastically improved.

The mold 85 shown in FIG. 17 is different in the length and shape of the notch portions of the mold 36 and the lower mold described above, and the other portions are the same or equivalent. That is, notches 88A and 88B are partially formed at both edges 48a and 48b of the recess 48 of the lower mold 87 of the mold 85, and the notches 88A and 88B are respectively uniform width portions 88a. And a variable width portion 88b. More specifically, uniform width portion 88a extends from the vent zone F side of the end face 87b of the lower mold 87, the width W ₃ being becomes uniform. On the other hand, the variable width portion 88b extends continuously from the end portion of the gate opening G side of the uniform width portion 88a, the width W ₄ toward the gate port G side is gradually reduced (that is, the gate port G side width W ₄ toward the degassing unit F side from is gradually increased). Therefore, the width _{W 4} at an arbitrary position of the uniform width portion 88a or variable width portion 88b _{P 3} (first position), the position _{P 4} (a variable-width portion 88b that is from its position _{P 3} to the gate port G side It is wider than the width W ₄ at the second position). In addition, the notches 88A, the length _{L c} of the end surface 87b of the 88B is shorter than the length _{L A} of the lower die 87. Note that the depth of the groove formed by the notches 88A and 88B is uniform in the direction outward from the cavity C (Y direction in FIG. 17), gradually increasing or decreasing, and two steps. Any of the configuration modes may be used (see FIGS. 5 and 7 to 10).

  Even with the notches 88A and 88B, the same bubble suppression effect as that of the notches 50A and 50B described above can be obtained. That is, even if it is a groove part partially formed in the above-mentioned cavity C, the same effect is acquired by arrange | positioning the groove part to the degassing part F side. Further, similarly to the notches 78A and 78B, the volume of the groove to be formed can be reduced, so that the amount of molten resin necessary for filling can be reduced also in the notches 88A and 88B. Furthermore, since the eaves portion of the molded product generated in the groove portion formed by the notches 88A and 88B can be reduced, labor and time required for removing the eaves portion are significantly reduced. In addition, when the cutout portion is formed in the mold by cutting, the cutout portions 88A and 88B have a shorter cutting length than the cutout portions 50A and 50B, and therefore labor and time required for the processing. Is significantly reduced. In this embodiment as well, by designing the groove depth to be 0.05 mm or less, a situation in which the eaves portion is generated in the molded product is significantly suppressed, and the manufacturing efficiency of the magnet block 20 can be drastically improved.

  Hereinafter, in order to further clarify the effects of the present invention, description will be made using examples and comparative examples. 11 and 12 are graphs showing the measurement results of the magnetic flux density in the longitudinal direction of the two magnet blocks. That is, the horizontal axis of the graphs of FIGS. 11 and 12 indicates the linear distance from one end of the magnet block, and the vertical axis indicates the magnetic flux density (mT). FIG. 11 shows data MB-1 of the example, and is measurement data of a magnet block manufactured using a mold similar to the mold 60 shown in FIG. FIG. 12 is data MB-2 of the comparative example, and is measurement data of a magnet block manufactured using a mold similar to the conventional mold 100 shown in FIG.

  More specifically, in the above examples and comparative examples, Sr ferrite (90 wt%) and polyamide resin (10 wt%) were used as the magnet block material.

And in the Example, the magnet block (plastic magnet) was injection-molded in the magnetic field using the metal mold | die similar to the metal mold | die shown in FIG. Incidentally, the groove depth _{D 2} of the first groove is 0.02 mm, the groove depth _{D 3} of the second groove was 0.05 mm. Demagnetization was performed after molding. A magnet block having an outer peripheral curved surface width of 15 mm, a radial thickness of 5 mm, an opening angle of 60 degrees, and a longitudinal length of 308 mm was produced. Thereafter, the magnet block was magnetized, and the magnetic flux density at a position 1.5 mm above the center position of the outer peripheral curve of the magnet block was measured along the longitudinal direction. A gauss meter was used for measuring the magnetic flux density.

  On the other hand, also in the comparative example, the same molding and measurement as in the example were performed using the same mold as the mold shown in FIG.

  From the graphs shown in FIG. 11 and FIG. 12, MB-2 has a sharp drop in magnetic flux density measured at three locations, whereas MB-1 has no such drop. . That is, the magnetic flux density (magnetic characteristics) in the longitudinal direction of the magnet block is clearly superior to that of MB-1. In addition, MB-2 was measured at two locations, such as a continuous noise-like waveform, although the amplitude was not as large as the steep drop described above. In MB-1, occurrence of such a noise waveform is also suppressed.

  Here, when the cross section of the place where the drop of the magnetic flux density of MB-2 was confirmed was observed, as shown in FIG. 13, large bubbles were confirmed near the center of the cross section. On the other hand, even when the cross section of MB-1 was observed, no conspicuous bubbles were confirmed as shown in FIG. From the above results, the causal relationship between the stability of the magnetic properties of the magnet block and the bubbles inside it was clarified, and it was found that the magnetic properties were improved in the magnet block 20 in which the generation of bubbles was suppressed. .

  The inventors also measured the magnetic flux density for a magnet block manufactured using a mold similar to the mold 75 shown in FIG. As a result, the same data as the example data MB-1 in FIG. 11 was obtained. From this, it was found that even the mold 75 shown in FIG.

  The present invention is not limited to the above embodiment, and various modifications are possible. For example, the cutout portion is not limited to an embodiment in which only the lower die is formed as long as the above-described groove portion can be formed, and may be an embodiment in which only the upper die is formed or an embodiment in which both the upper die and the lower die are formed. Good. In addition to providing a notch portion in which both groove portions have the same shape, for example, a notch portion in which one groove portion has a one-stage configuration and the other groove portion has a two-step configuration, or one groove portion. It is also possible to provide a notch that is uniform in width and gradually changes in width of the other groove. Furthermore, the notch is not limited to the form formed on both edges, and may be formed only on one edge as appropriate.

  Moreover, you may provide a notch part which a groove part changes the width | variety gradually along the direction in alignment with the longitudinal direction of a metal mold | die. Furthermore, a part or all of the inner surface of the groove part may be formed of a curved surface.

1 is a schematic perspective view of a developing roll according to an embodiment of the present invention. It is the II-II sectional view taken on the line of the image development roll shown in FIG. FIG. 3 is a sectional view of the developing roll shown in FIG. 1 taken along the line III-III. It is the schematic plan view which showed the metal mold | die used when producing the magnet block which concerns on embodiment of this invention. It is the alpha-alpha sectional view taken on the line of the metal mold | die shown in FIG. It is the figure which showed the procedure which produces a magnet block using the metal mold | die shown in FIG.4 and FIG.5. It is the schematic sectional drawing which showed the metal mold | die of a different aspect. It is the schematic sectional drawing which showed the metal mold | die of a different aspect. It is the schematic sectional drawing which showed the metal mold | die of a different aspect. It is the schematic sectional drawing which showed the metal mold | die of a different aspect. It is the graph which showed the measurement result which concerns on embodiment of this invention. It is the graph which showed the measurement result which concerns on a prior art. It is a cross-sectional photograph of the magnet block which concerns on an Example. It is a cross-sectional photograph of the magnet block which concerns on an Example. It is the schematic plan view which showed the metal mold | die of a different aspect. It is the schematic plan view which showed the metal mold | die of a different aspect. It is the schematic plan view which showed the metal mold | die of a different aspect. It is the figure which showed the metal mold | die which concerns on a prior art.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Developing roll, 14 ... Magnet roll, 18 ... Shaft, 20, 20A-20E ... Magnet block, 20a ... Inner curved surface, 20b ... Outer curved surface, 20c, 20d ... Both side plane, 36, 36A, 36B, 60, 60A 75, 80, 85, 100 ... mold, 42, 62, 76, 81, 86, 102 ... upper mold, 44, 64, 77, 82, 87, 106 ... lower mold, 46, 48, 66, 68, 106, 108 ... recess, 48a, 48b, 68a, 68b ... edge, 50A, 50B, 70A, 70B, 78A, 78B, 83A, 83B, 88A, 88B ... notch, 52A, 52B, 72A, 72B ... Groove, 54 ... molten resin, 56 ... molded product, 58A, 58B ... eaves, C ... cavity, F ... gas vent, G ... gate port, S ... parting surface.

Claims (25)

Used to produce the magnet block of a magnet roll having a shaft and a plurality of magnet blocks,
A first mold having a first recess extending along a longitudinal direction of the magnet block to be manufactured, and forming an outer peripheral curved surface of the magnet block by the first recess, and the magnet block to be manufactured A second mold that has a second recess extending along the longitudinal direction of the magnet block, and a second mold that forms an inner peripheral curved surface and both side planes of the magnet block by the second recess, The edge parallel to the longitudinal direction of the first recess in the edge of the first recess, and the edge parallel to the longitudinal direction of the second recess in the edge of the second recess At least one of the first and second recesses is formed with a notch that forms a groove extending outwardly along the parting surface from the cavity formed by the first and second recesses, along the edge. Using the mold A method of manufacturing a net block,
Combining the first mold and the second mold to form the cavity;
Injecting and filling molten resin containing magnetic powder into the cavity;
And a step of solidifying the molten resin injected and filled in the cavity.   The method for manufacturing a magnet block according to claim 1, further comprising a step of removing a portion corresponding to the groove portion of the molded product obtained by solidification of the molten resin.   The manufacturing method of the magnet block of Claim 1 or 2 with which the said notch part is formed over the substantially full length of the said edge part.   The magnet according to claim 1 or 2, wherein the notch is partially formed along the edge and extends from a side opposite to a side on which the molten resin is injected and filled. Block manufacturing method.   The width | variety in the 1st position of the said notch part is wider than the width | variety in the 2nd position in the side by which the said molten resin is injection-filled from the said 1st position. The manufacturing method of the magnet block of description.   6. The magnet block according to claim 1, wherein the cutout portion includes a portion whose width gradually increases from a side on which the molten resin is injected and filled toward an opposite side thereof. Production method.   The said groove part is a manufacturing method of the magnet block as described in any one of Claims 1-6 whose groove depth is substantially uniform regarding the direction which goes outside from the said cavity.   The said groove part is a manufacturing method of the magnet block as described in any one of Claims 1-6 in which the groove depth is increasing gradually or decreasing gradually regarding the direction which goes outside from the said cavity.   The said groove part is a manufacturing method of the magnet block as described in any one of Claims 1-8 whose groove depth is 0.1 mm or less. The groove is
A first groove adjacent to the cavity;
The magnet block manufacturing method according to any one of claims 1 to 6, further comprising a second groove portion that is located outward from the first groove portion and deeper than the first groove portion.   The method of manufacturing a magnet block according to claim 10, wherein the first and second groove portions have substantially uniform groove depths in a direction outward from the cavity.   The method for manufacturing a magnet block according to claim 10, wherein at least one of the first and second groove portions has a groove depth that gradually increases or gradually decreases in a direction outward from the cavity. .   The groove depth of the first groove portion is 0.05 mm or less, and the groove depth of the second groove portion is in the range of 0.02 mm to 1 mm. The manufacturing method of the magnet block of one term. Used to produce the magnet block of a magnet roll having a shaft and a plurality of magnet blocks,
A first mold having a first recess extending along a longitudinal direction of the magnet block to be produced, and forming an outer peripheral curved surface of the magnet block by the first recess;
A second mold that has a second recess extending along the longitudinal direction of the magnet block to be produced, and that forms an inner circumferential curved surface and both side planes of the magnet block by the second recess;
The edge parallel to the longitudinal direction of the first recess in the edge of the first recess, and the edge parallel to the longitudinal direction of the second recess in the edge of the second mold At least one of the portions is formed with a notch that forms a groove extending outwardly from the cavity formed by the first and second recesses along the parting surface along the edge. The magnet block mold.   The magnet block mold according to claim 14, wherein the notch is formed over substantially the entire length of the edge.   The magnet block mold according to claim 14, wherein the notch is partially formed along the edge and extends from a side opposite to a side on which the molten resin is injected and filled. .   The width | variety in the 1st position of the said notch part is wider than the width | variety in the 2nd position in the side by which the said molten resin is injection-filled from the said 1st position. The magnet block mold described.   18. The magnet block according to claim 14, wherein the cutout portion includes a portion whose width gradually increases from a side on which the molten resin is injected and filled toward an opposite side thereof. Mold.   The mold of the magnet block according to any one of claims 14 to 18, wherein the groove has a substantially uniform groove depth in a direction from the cavity toward the outside.   The mold of the magnet block according to any one of claims 14 to 18, wherein a groove depth of the groove portion is gradually increased or gradually decreased with respect to a direction outward from the cavity.   The said groove part is a metal mold | die of the magnet block as described in any one of Claims 14-20 whose groove depth is 0.1 mm or less. The groove is
A first groove adjacent to the cavity;
The mold of the magnet block according to any one of claims 14 to 18, further comprising a second groove portion that is located outside the first groove portion and deeper than the first groove portion.   23. The magnet block mold according to claim 22, wherein the first and second groove portions have substantially uniform groove depths in a direction outward from the cavity.   The mold of the magnet block according to claim 22, wherein at least one of the first and second groove portions has a groove depth gradually increasing or gradually decreasing in a direction outward from the cavity. . The groove depth of the first groove portion is 0.05 mm or less, and the groove depth of the second groove portion is within a range of 0.02 mm to 1 mm. The magnet block mold according to one item.

Images