JP7159709B2 - Magnet roll manufacturing equipment and molds used in the manufacturing equipment - Google Patents

Description

The present invention relates to a magnet roll manufacturing apparatus for manufacturing a magnet roll used in a developing roll used for transporting a magnetic developer, and a mold used in the manufacturing apparatus.

In an electrophotographic apparatus, an electrostatic recording apparatus, or the like, an electrostatic charge image is formed on an image carrier such as a photoreceptor or dielectric, and a magnetic developer containing toner is conveyed to a development area by a developing roll to form the electrostatic charge image. is developed, and the resulting toner image is transferred to paper and fixed to form an image. A magnet roll having a plurality of fixed magnetic poles on its outer peripheral surface is used as the developing roll. Various magnet rolls and manufacturing methods and apparatuses thereof have been conventionally proposed (Patent Documents 1 to 3, etc.).

FIG. 6 is a cross-sectional view showing a general configuration of a developing roll. The developing roll 40 includes a magnet roll 41 made of a cylindrical permanent magnet, a shaft 42 coaxially fixed to the center of the magnet roll 41, a cylindrical sleeve 43 accommodating the magnet roll 41 and the shaft 42, Flanges 44, 44 fixed to the inside of both ends in the longitudinal direction of the sleeve 43, bearings 45, 45 fitted inside the flanges 44, 44, and a seal 46 provided on the end face of one flange 44. have.

The magnet roll 41 is composed of a bonded magnet obtained by solidifying a kneaded material of magnetic powder and binder resin, and a plurality of magnetic poles extending in the axial direction are formed on the outer peripheral surface of the magnet roll 41 . There are various shapes of the magnet roll 41. Patent Documents 1 and 2 disclose a magnet roll 41 having a circular cross section. A magnet roll 41 having a C-shaped cross section is disclosed.

The sleeve 43 is made of a non-magnetic metal material such as an aluminum alloy or non-magnetic stainless steel. The shaft 42 and the sleeve 43 are relatively rotatable via bearings 45 , 45 .

In the developing roller 40 having such a configuration, the magnet roller 41 and the sleeve 43 rotate relative to each other, so that the magnetic developer is attracted to the outer peripheral surface of the sleeve 43 to form a magnetic brush. A developer is transported to visualize an electrostatic charge image.

WO99/38174 JP-A-2001-15315 Japanese Patent Application Laid-Open No. 2003-100511

Magnet rolls made of bonded magnets are generally manufactured by extrusion molding or injection molding. Compared to injection molding, extrusion molding has advantages such as continuous processing, short processing time, and low cost of molds, so extrusion molding is often used.

Patent Literature 1 discloses an extrusion molding device for manufacturing a magnet roll. A molten kneaded material of the magnetic powder and the binder resin is conveyed through the mandrel into a mold, which is a molding space. The mold has an elongated center shaft (in Patent Document 1, refers to a portion of the mandrel with a constant diameter within the molding space) for molding the inner peripheral surface of the magnet roll to be manufactured. A magnetic field generating member is arranged in the mold. The melted and kneaded material of the magnetic powder and the binder resin that has been transported is molded into a magnet roll having a desired shape as it passes through the mold (molding space), and is shaped by the application of a magnetic field from the magnetic field generating member. A plurality of magnetic poles extending in the axial direction are formed on the outer peripheral surface.

The extrusion molding apparatus disclosed in Patent Document 1 has the following drawbacks. A center shaft that forms the inner peripheral surface of the magnet roll must have a certain length or longer. As a result, the center shaft may bend or tilt at the start of work or at the time of replacement of the manufactured magnet rolls, resulting in product defects. Therefore, in order to eliminate the defect of the center shaft, it is necessary to disassemble the mold components, including the mandrel, heater, etc., and correct the bending or inclination of the center shaft. Therefore, this correction process takes a long time. In addition, since the temperature inside the mold is lowered when the mechanism including the heater is removed, the molten kneaded material is solidified, making it difficult to perform the decomposition process. Alternatively, since the temperature of the kneaded material is lowered when reassembling and extruding, it takes time to raise the temperature again. For this reason, there is a problem that the manufacturing efficiency is greatly reduced when the center shaft is bent or inclined.

SUMMARY OF THE INVENTION The present invention has been made in view of such circumstances, and enables the center shaft to be easily adjusted when the center shaft is bent or tilted, and these defects can be easily corrected. To provide a magnet roll manufacturing apparatus capable of suppressing a significant decrease in manufacturing efficiency without the need to remove a mechanism including a heater when adjusting a center shaft, and to provide a mold used in the manufacturing apparatus. .

A manufacturing apparatus for a magnet roll according to the present invention is a manufacturing apparatus for manufacturing a magnet roll by passing a melted kneaded material of a magnetic powder and a binder resin through a mold, wherein the mold is a flow through which the kneaded material flows. and a center shaft inserted into the flow channel, the center shaft being separable into a plurality of portions along the flow direction of the kneaded material, and the kneaded material among the plurality of portions. The most downstream part of the article is characterized by being removable to the outside of the mold.

In the mold of the magnet roll manufacturing apparatus according to the present invention, the center shaft inserted into the flow path through which the molten kneaded material of the magnetic powder and the binder resin flows extends in the flow direction (axial direction). It can be separated into multiple parts, and the most downstream part of the kneaded material can be removed to the outside. Therefore, when a problem such as bending or tilting of the center shaft occurs, the problem can be easily corrected by removing and adjusting the most downstream portion (tip portion). At this time, since it is not necessary to disassemble the entire mold, the temperature inside the mold does not drop, and correction can be performed while maintaining a constant and appropriate temperature. Therefore, the manufacturing efficiency of the magnet roll does not decrease so much.

In the apparatus for manufacturing a magnet roll according to the present invention, the mold includes a center support through which the flow path passes to support the center shaft, and a position of the center support in a direction intersecting the flow direction of the kneaded material. and an adjusting member that adjusts the movement to the

In the mold of the magnet roll manufacturing apparatus according to the present invention, there is a center support that supports the center shaft and moves in a direction intersecting the flow direction (axial direction) of the kneaded material by external adjustment. is provided. When a problem such as bending or tilting of the center shaft occurs, the problem can be easily corrected by adjusting the center support from the outside with an adjusting member. At this time, since it is not necessary to disassemble the entire mold, the temperature inside the mold does not drop, and correction can be performed while maintaining a constant and appropriate temperature. Therefore, the manufacturing efficiency of the magnet roll does not decrease so much.

The magnet roll manufacturing apparatus according to the present invention is characterized in that the center shaft is made of a non-magnetic material.

In the magnet roll manufacturing apparatus according to the present invention, the center shaft is made of a non-magnetic material. Therefore, there is no adverse effect when forming a plurality of magnetic poles on the outer peripheral surface of the manufactured magnet roll.

An apparatus for manufacturing a magnet roll according to the present invention is characterized by comprising an extruder for extruding and supplying a melted kneaded product of magnetic powder and binder resin to the mold.

In the magnet roll manufacturing apparatus according to the present invention, a melted kneaded product of magnetic powder and binder resin is extruded and supplied from an extruder to a mold. Therefore, a magnet roll is manufactured by a series of extrusion processes.

The mold according to the present invention is a mold through which a molten kneaded material of a magnetic powder and a binder resin, which are raw materials of the magnet roll, is passed when manufacturing a magnet roll, and in which the kneaded material flows. and a center shaft inserted into the flow channel, the center shaft being separable into a plurality of portions along the flow direction of the kneaded material, and the kneaded material among the plurality of portions. The most downstream part of is removable to the outside.

The mold according to the present invention includes a center support through which the channel passes through to support the center shaft, and an adjusting member that moves and adjusts the position of the center support in a direction intersecting with the flow direction of the kneaded material. It is characterized by having

According to the present invention, when a problem such as bending or tilting of the center shaft occurs, the problem can be easily corrected without removing the entire mold. Since there is no need to disassemble the entire mold, correction can be performed while the temperature inside the mold is kept constant, thereby suppressing a decrease in manufacturing efficiency.

1 is a sectional view showing the overall configuration of a magnet roll manufacturing apparatus according to the present invention; FIG. 1 is an external perspective view of a mold in a magnet roll manufacturing apparatus according to the present invention; FIG. FIG. 3 is a cross-sectional view showing a detailed configuration of a mold in the magnet roll manufacturing apparatus according to the present invention; FIG. 4 is a perspective view showing a center support that the mold has; 4 is an enlarged cross-sectional view taken along line AA of FIG. 3; FIG. FIG. 2 is a cross-sectional view showing a general configuration of a developing roll;

Hereinafter, the present invention will be described in detail based on the drawings showing its embodiments. FIG. 1 is a cross-sectional view showing the overall configuration of a magnet roll manufacturing apparatus according to the present invention. A magnet roll manufacturing apparatus 10 (hereinafter also simply referred to as a manufacturing apparatus 10) is configured by connecting a mold 1 and an extruder 2 to each other. Using this manufacturing apparatus 10, the magnet roll 41 used for the developing roll 40 shown in FIG. 6 is manufactured by extrusion molding. That is, a melted kneaded material of magnetic powder and a binder resin (hereinafter also referred to simply as a melted kneaded material) is conveyed from an extruder 2 to a mold 1, and the conveyed melted kneaded material is passed through the mold 1. The magnet roll 41 is manufactured by being formed into a desired shape by passing through.

First, the configuration of the mold 1, which is a feature of the present invention, will be described. FIG. 2 is an external perspective view of the mold 1, and FIG. 3 is a sectional view showing the detailed configuration of the mold 1. As shown in FIG. Note that FIG. 2 shows a configuration excluding a heater 21, which will be described later.

The mold 1 includes a mold base 11, a flow path forming mold part 12, a mold outer yoke 13, and a mold A tip cap 14 is provided, and these are integrally fixed with screws.

The mold base 11, the flow path forming mold portion 12, the mold outer yoke 13, and the mold front end cap 14 are all cylindrical. The mold base 11 and the flow path forming mold portion 12 have substantially the same outer diameter, and the mold outer yoke 13 and the mold tip cap 14 have substantially the same outer diameter. The outer diameter of the portion 12 is larger than the outer diameters of the mold outer yoke 13 and mold tip cap 14 . The inner diameter of the flow path forming mold part 12 is the largest at the base end (the right end in FIG. 3), gradually decreases toward the center, and remains constant from the center to the tip. The inner diameter of the mold base 11 is substantially equal to the inner diameter of the base end of the flow path forming mold portion 12 . The inner diameter of the mold outer yoke 13 is larger than the inner diameter of the mold base 11 . The inner diameter of the mold front end cap 14 is approximately equal to the inner diameter of the front end portion of the flow path forming mold portion 12 .

A thin-walled cylindrical flow path forming pipe 15 and a die 16, which serve as flow paths for the melted and kneaded material, are fitted into the communicating hollow portions of the flow path forming mold part 12, the mold outer yoke 13, and the mold tip cap 14. is A flow path forming pipe 15 is provided on the base end side of a center support 18, which will be described later, and a die 16 is provided on the tip side thereof. The flow path forming pipe 15 extends to the tip of the flow path forming die portion 12 . The outer diameter of the flow path forming pipe 15 is slightly smaller than the inner diameter of the tip portion of the flow path forming die portion 12 . The die 16 extends to the mold tip cap 14 and has an outer diameter slightly smaller than the inner diameter of the mold tip cap 14 . The molten kneaded material, which is the raw material of the magnet roll 41, is conveyed from the flow path forming pipe 15 into the die 16 from the upstream side (base end side) to the downstream side (tip side). (see arrow in Figure 3). The shape of the inner peripheral surface of the die 16 defines the shape of the outer peripheral surface of the magnet roll 41 to be manufactured.

A long cylindrical center shaft 17 extending in the axial direction is inserted through the passage forming pipe 15 and the die 16 . The center shaft 17 is made of a non-magnetic material such as stainless steel having good thermal conductivity. The shape of the peripheral surface of the center shaft 17 defines the shape of the inner peripheral surface of the magnet roll 41 to be manufactured. The center shaft 17 is composed of a shaft distal end portion 17a, which is a portion on the distal end side, and a shaft base portion 17b, which is a portion on the proximal end side. A tip portion of the shaft tip portion 17 a protrudes from the opening of the mold tip cap 14 to the outside. The length of the shaft tip portion 17a is about 100 mm when the length of the manufactured magnet roll 41 is about 80 mm. The shaft base portion 17 b extends over the entire hollow portion of the flow path forming mold portion 12 , and its base end is supported and fixed to the mold base 11 .

The proximal end of the shaft distal end portion 17a forms a recess 17c extending in the axial direction, and the inner surface of the recess 17c is threaded. A tip portion of the shaft base portion 17b is a small diameter portion 17d, and the outer surface of the tip side of the small diameter portion 17d is threaded. By screwing these screws together, the shaft distal end portion 17a and the shaft base portion 17b are normally connected to form an integrated center shaft 17. As shown in FIG. If necessary, by unscrewing these screws, it is possible to remove only the shaft tip portion 17a to the outside. That is, the center shaft 17 can be separated into a shaft tip portion 17a and a shaft base portion 17b in the axial direction, and the shaft tip portion 17a can be removed to the outside. When removing the shaft tip portion 17a to the outside, none of the mold base 11, the flow path forming mold portion 12, the mold outer yoke 13, and the mold tip cap 14 need to be removed (disassembled).

A hollow disc-shaped center support 18 is provided in a hollow portion slightly closer to the proximal end from the center of the mold outer yoke 13 . FIG. 4 is a perspective view showing the center support 18 of the mold 1. FIG. The installation position of the center support 18 corresponds to the connection position of the shaft tip portion 17a and the shaft base portion 17b, as shown in FIG. FIG. 5 is an enlarged cross-sectional view taken along line AA of FIG. The center support 18 is made of non-magnetic material such as stainless steel.

The outer diameter of the center support 18 is slightly smaller than the inner diameter of the mold outer yoke 13 . In the hollow portion of the center support 18, four wings 18b equally spaced in the circumferential direction at intervals of 90 degrees extend in the thickness direction (axial direction) of the center support 18 (Fig. 4). , see Figure 5). Cylindrical guide portions 18a, 18a are provided on the base end side and the tip end side of the hollow portion of the center support 18 in the flow direction (axial direction) of the molten kneaded material. The distal end portion of the flow path forming pipe 15 is inserted into the cylindrical guide portion 18a on the proximal end side, and the proximal end portion of the die 16 is inserted into the cylindrical guide portion 18a on the distal end side (see FIG. 3). The center shaft 17 (the small-diameter portion 17d of the shaft base portion 17b) is inserted through the central hollow portion of the wing portion 18b of the center support 18. As shown in FIG. The center support 18 thereby supports the center shaft 17 . The wing portions 18b of the center support 18 divide the passage of the molten kneaded material flowing from the passage forming pipe 15 to the die 16 into four.

Four screw holes 13a are formed in the outer yoke 13 of the mold at the same position in the axial direction as the position where the center support 18 is provided, and are equally spaced apart by 90 degrees in the circumferential direction. (See Figure 5). An adjusting screw 19 as an adjusting member is fitted in each screw hole 13a. Four recesses 18c are formed in the outer peripheral surface of the center support 18 at positions corresponding to the four screw holes 13a (see FIG. 4), and the adjusting screws 19 abut on the recesses 18c. . By adjusting the adjustment screw 19, the pressing force of the adjustment screw 19 applied to the center support 18 is changed, so that the movement of the center support 18 in the direction crossing the flow direction of the molten kneaded material is controlled. It's becoming Due to the movement of the center support 18, the center shaft 17 also moves in a direction crossing the axial direction (flow direction of the molten kneaded material). In this example, movement in four directions perpendicular to the flow direction of the molten kneaded material (up, down, left, and right in FIG. 5) is controlled. The adjustment margin at this time is about 0.5 mm on one side.

An orienting magnetic circuit 20 is provided in a hollow portion extending from the center to the tip of the mold outer yoke 13 so as to surround the die 16 . The orienting magnetic circuit 20 is composed of a magnetic field generating coil and an orienting yoke. The orienting magnetic circuit 20 is configured to apply a magnetic field to the molten kneaded material conveyed through the die 16 in order to form desired magnetic poles on the outer peripheral surface of the magnet roll 41 to be manufactured.

A heater 21 is installed on the outer peripheral surfaces of the mold base 11 and the flow path forming mold portion 12 . The heater 21 is configured to maintain the temperature inside the mold 1 at a predetermined temperature so that the supplied molten kneaded material maintains a desired viscosity.

A mandrel 22 is fitted in the hollow portion of the mold base 11, and the tip of the mandrel 22 is fixed inside the large-diameter portion on the base end side of the shaft base 17b.

Next, the configuration of the extruder 2 will be described with reference to FIG. The extruder 2 has a barrel 32 having a hopper 31 on the base end side, a screw 33 arranged inside, and an adapter 34 installed at the tip of the barrel 32 . The mold base 11 of the mold 1 is connected to the outlet of the adapter 34 .

A process of manufacturing a magnet roll 41 made of a bond magnet using the manufacturing apparatus 10 having the above-described configuration, and a process of manufacturing a developing roll 40 as shown in FIG. 6 using the manufactured magnet roll 41 will be described below. do.

A kneaded material of a magnetic powder and a binder resin, which are raw materials, is charged from a hopper 31 into a barrel 32 . For example, nitrided rare earth magnetic powder is used as the magnetic powder, and elastomer resin is used as the binder resin. Needless to say, the magnetic powder and the binder resin are not limited to these types. A shearing force is applied to the raw material (kneaded material of magnetic powder and binder resin) put into the barrel 32 by rotating the screw 33, and the kneaded material is heated and melted at a temperature of about 150 to 230 ° C. to melt the gold. Transfer to mold 1.

The melted and kneaded material conveyed to the mold 1 is carried into the flow path forming pipe 15 through the mold base 11 and the hollow portion of the flow path forming mold portion 12 . Then, while traveling from the passage forming pipe 15 through the die 16 (arrow in FIG. 3), the melt-kneaded material is shaped so that its outer peripheral surface follows the shape of the inner peripheral surface of the die 16. The inner peripheral surface thereof is formed in a shape following the shape of the peripheral surface of the center shaft 17 to form a cylindrical shape. Here, when passing through the center support 18, the molten kneaded material is divided into four flow paths, which is suitable for removing air bubbles.

A magnetic field is applied to the cylindrical magnet body from the orienting magnetic circuit 20 to form a desired plurality of magnetic poles extending in the axial direction on the outer peripheral surface of the magnet body. Then, the radially anisotropic molded body is extruded from the mold 1 .

The extruded compact is cut into a predetermined length to obtain a magnet roll 41 made of a long cylindrical bonded magnet having a plurality of axially extending magnetic poles provided on the outer peripheral surface. A shaft 42 is coaxially fixed to the center of the magnet roll 41 . Flanges 44, 44 are fitted to both ends of the shaft 42, one end via a bearing 45 and a seal 46, and the other end via a bearing 45 only. The flanged magnet roll 41 is inserted through the sleeve 43 . Finally, both ends of the sleeve 43 are fixed to the flanges 44, 44 by caulking, and the developing roll 40 is produced.

When manufacturing the magnet roll 41, the center shaft 17 may be bent or tilted. Defects can be detected by inspecting the degree of eccentricity in the manufactured magnet roll 41, the magnetic field distribution on the outer peripheral surface, and the like. Since the center shaft 17 has a cantilevered structure on the proximal side, such a problem is likely to occur on the distal side. If the manufacturing is continued while the defect is left as it is, the manufacturing yield will be lowered due to the effect of the defect. Therefore, it is necessary to eliminate the defect.

In such a case, in the mold 1 of the present invention, the center shaft 17 can be separated into the shaft tip portion 17a and the shaft base portion 17b. Problems such as bending and inclination are corrected, and then the corrected shaft tip portion 17a is returned to its original position in the mold 1, so that the problems can be easily resolved. Further, at this time, since it is not necessary to disassemble the other components of the mold 1, the straightening process can be performed in a short time. In addition, since the other components of the mold 1 are not decomposed, the temperature inside the mold 1, which is kept constant by the heater 21, does not drop, and the magnetic powder and the binder resin remain in a molten state. Since the straightening process can be performed as it is, the manufacturing efficiency is not significantly lowered.

Further, in the mold 1 of the present invention, the center support supports the center shaft 17 and moves in the direction crossing the flow direction of the molten kneaded material by adjusting the pressing force of the adjustment screw 19 from the outside. 18. Therefore, in the event that the center shaft 17 bends or tilts, the problem can be easily corrected by adjusting the pressing force of the adjustment screw 19 applied to the center support 18 from the outside. At this time, since it is not necessary to disassemble the components of the mold 1 at all, the straightening process can be performed in a short time. In addition, since the components of the mold 1 are not decomposed, the temperature inside the mold 1, which is kept constant by the heater 21, does not drop, and the magnetic powder and the binder resin are corrected while maintaining the molten state. Since the processing can be performed, a large decrease in manufacturing efficiency does not occur. Further, by adjusting the pressing force of the adjusting screw 19, it is possible to prevent the center shaft 17 from bending, tilting, and other problems.

In the embodiment described above, the center shaft 17 is configured to be separable into two portions, the shaft tip portion 17a and the shaft base portion 17b. A certain configuration may be used. Even with such a configuration, the portion on the most advanced side (the most downstream side of the melted and kneaded material) can be removed to the outside.

In the above-described embodiment, the pressing force is adjusted from four locations equally distributed in the circumferential direction with respect to the center support 18, but the pressing force is not limited to four locations, and the pressing force may be adjusted from two, three, or five or more locations. It is good also as a structure which adjusts a pressure.

In the above-described embodiment, the center support 18 is provided corresponding to the connection position of the shaft tip portion 17a and the shaft base portion 17b, but the installation position of the center support 18 is not limited to this. It is preferable to provide the center support 18 at a position where the center shaft 17 is likely to bend or tilt.

In the above-described embodiment, the case of manufacturing the cylindrical magnet roll 41 having a circular cross section has been described. can be similarly applied. In this case, a die having a die with a portion of the area in the circumferential direction thicker than the other area is used.

In the above-described embodiment, the orienting magnetic circuit 20 for applying a magnetic field to the compact is composed of the magnetic field generating coil and the orienting yoke. A magnetic field may be applied to the compact by arranging the magnetic field on the compact.

It should be noted that the disclosed embodiments should be considered as examples and not restrictive in all respects. The scope of the present invention is indicated by the scope of the claims rather than the above description, and is intended to include all modifications within the scope and meaning equivalent to the scope of the claims.

REFERENCE SIGNS LIST 1 mold 2 extruder 10 magnet roll manufacturing device 11 mold base 12 channel forming mold section 13 mold outer yoke 13a screw hole 14 mold tip cap 15 channel forming pipe (channel)
16 die (flow path)
17 Center shaft 17a Shaft tip 17b Shaft base 17c Recess 17d Small diameter portion 18 Center support 18a Cylindrical guide 18b Wing 18c Recess 19 Adjusting screw (adjusting member)
20 magnetic circuit for orientation 21 heater 22 mandrel 40 development roll 41 magnet roll

Claims (4)

In a manufacturing apparatus for manufacturing a magnet roll by passing a molten kneaded product of magnetic powder and binder resin through a mold,
The mold has a channel through which the kneaded material flows, and a center shaft inserted through the channel,
The center shaft can be separated into a plurality of parts along the flow direction of the kneaded material,
A most downstream portion of the kneaded material among the plurality of portions is removable to the outside of the mold , and the mold includes a center support that is penetrated by the flow path and supports the center shaft. and an adjusting member for moving and adjusting the position of the center support in a direction intersecting the flowing direction of the kneaded material . 2. A magnet roll manufacturing apparatus according to claim 1, wherein said center shaft is made of a non-magnetic material. 3. The apparatus for manufacturing a magnet roll according to claim 1, further comprising an extruder for extruding and supplying a melted kneaded product of the magnetic powder and the binder resin to the mold. When manufacturing a magnet roll, in a mold through which a molten kneaded material of a magnetic powder and a binder resin, which are raw materials of the magnet roll, is passed, a flow path through which the kneaded material flows, and a flow path in the flow path and a center shaft inserted through the
The center shaft is separable into a plurality of parts along the flow direction of the kneaded material, and the most downstream part of the kneaded material among the plurality of parts is detachable to the outside. A mold characterized by comprising a center support through which a passage passes through to support the center shaft, and an adjusting member for moving and adjusting the position of the center support in a direction intersecting with the flow direction of the kneaded material. .

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