JPH0529122B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention relates to a magnet roller, which is a resin magnet used in a magnetic brush developing roller used in copying machines, printers, etc., and a method for manufacturing the same. [Prior art] Magnet rollers conventionally used in copying machines and other equipment have generally been made of isotropic or anisotropic sintered magnets or resin magnets pasted or press-fitted onto a core metal. It was spot on. or,
In recent years, the injection molding method has been used to produce
A large number of applications have been filed, including JP-A No. 56-108207, in which polar anisotropic orientation integral molding is performed internally by applying Patent Publication No. 28287 and JP-B No. 56-5045. However, in bonding sintered magnets in the conventional example, there were problems such as easy chipping, troublesome bonding, and high cost. Furthermore, sintered integrally molded magnets also have problems such as poor yields and poor dimensional accuracy due to quenching cracks and warping, as well as problems such as being heavy and requiring high costs due to secondary processing. Further, even when bonding resin magnets with rubber or plastic, there are still problems such as high cost due to adhesion, secondary processing, etc. For this reason, in recent years, one-piece molded magnets made of resin magnets have also appeared. However, isotropic materials currently lack magnetic force. Therefore, many attempts have been made to make magnetic rollers anisotropic. [Problems to be solved by the invention] However, since radial orientation is impossible with long, solid or hollow magnetic rollers,
Integration by applying polar anisotropic orientation or bipolar orientation, which has been attempted in motor rollers, is generally performed. A schematic cross-sectional view of the polar anisotropically oriented product is shown in FIG. In order to achieve polar anisotropic orientation in this manner, a device in which a large number of magnetic poles are arranged around the molded product is used, which makes the device complicated and increases manufacturing costs. Furthermore, as shown in FIG. 11, the magnetic powder near the surface is mainly oriented and the magnetic powder in the center is not oriented, so there is a problem that the surface magnetic flux density distribution is not sharp and its value is small. Further, a schematic cross-sectional view of the bipolar oriented product is shown in FIG. 10, and the manufacturing process thereof is shown in FIG. In the case of polar anisotropic orientation as described above, in order to effectively use most of the volume of the magnetic roller, it is possible to improve the magnetic efficiency and increase the degree of orientation even in the mold unless the magnetic roller is multipole. It is possible. However, in the case of bipolar orientation multipolar magnetization, since orientation is performed using a uniformly parallel magnetic field as shown in FIG. 9, a molded product as shown in FIG. 10 is obtained. For this reason, in areas where the energy of each magnetic powder in the magnet roller requires a high value as surface magnetic flux, the energy of each magnetic powder in the magnet roller is not all in a straight line, but is located a little far from the magnetic pole position on the magnet. In terms of position, the direction of the magnetic path differs from the position where the surface magnetic flux density is required, so as a result, although the magnetic efficiency is similar to radial orientation and the degree of orientation is high, the vector is shifted. The distribution decreases, and when magnetizing, the deviated part is not a magnetic path, so the vector is shifted, and each magnetic powder is not fully magnetized to the maximum value of magnetic force that it can exert, so even if it looks good at first glance, the result is has the disadvantage that the magnetic force is considerably inferior to that of polar anisotropic orientation. The present invention has been made in view of the above-mentioned problems, and its object is to provide a magnet roller with strong magnetic force and low manufacturing cost, and a method for manufacturing the same. [Means for Solving the Problems] The above-mentioned object of the present invention is to provide a magnet roller comprising a molded article molded and oriented from a resin material containing magnetic powder. The peripheral portion of the roller has a plurality of magnetic poles constituting three or more magnetic pole pairs consisting of a pair of opposing magnetomotive poles and a final magnetization pole, and the magnetic poles are formed by a straight line connecting the magnetomotive pole and the final magnetization pole of each magnetic pole pair. are arranged so that they are substantially parallel to each other on the cross section, and adjacent magnetic poles have different magnetic properties, and the magnetic powder is located at the center of the magnetic peak of each magnetic pole in the periphery of the cross section of the magnet roller. The magnet is oriented in a direction in which the magnets and magnets converge, and the magnet is oriented in a central portion of the cross section of the roller so as to be substantially parallel to a straight line connecting the magnetizing pole and the final magnetizing pole of each pair of magnetic poles. This is achieved by a roller and its manufacturing method. A schematic sectional view of one embodiment of the magnetic roller of the present invention is shown in FIG. In this embodiment, the magnet roller has a cylindrical shape, and on its circumferential surface there is a magnetic peak of an N pole (magnetizing pole) and an S pole (final magnetizing pole).
Three magnetic pairs consisting of magnetic peaks are provided, and the north and south poles are magnetized alternately on the circumferential surface. And the S pole and N pole of each magnetic pair
The straight lines connecting the poles are parallel on the plane of FIG. However, the positional relationship of this magnetic pair may be arranged so as not to be parallel depending on the object. Further, its shape is not limited to a cylindrical shape, but can be any cylindrical shape. As shown in Figure 1, the ferromagnetic powder between the north and south poles of this magnetic pair is oriented almost parallel to the line connecting the north and south poles in the center of the molded product, and the Near the poles and south poles, that is, near the circumferential surface, they are oriented so as to converge toward the center of the magnetic peaks of the north and south poles. Because of this orientation, a strong magnetic force is generated toward the center of each pole, resulting in a sharp magnetic peak as shown in FIG. The size of these magnetic peaks does not have to be the same as shown in Figure 6.
It may be made to have a different size as desired. Conventionally known materials can be used for the magnetic roller of the present invention. The method for manufacturing a magnetic roller of the present invention, which can be used to manufacture a magnetic roller having the above configuration, includes a) a cavity for molding the magnetic roller, and the outer circumference of the axial cross section of the cavity has the A magnetizing pole is arranged on one outer periphery of the cavity, and a final magnetizing pole that pairs with the magnetizing pole is arranged on the other outer periphery, and the starting and final magnetizing poles of each pair of magnetic poles pass through the center of the cavity. Prepare a molding mold arranged so that the lines of magnetic force are almost parallel, b) Inject a resin material containing magnetic powder for molding a magnet roller into the mold, and the magnetic powder in the resin material: Being magnetically oriented by the magnetic poles arranged on the outer periphery of the cavity, the magnetic powder in the vicinity of the starting and ending poles in the cavity is oriented in a direction converging toward the center of the magnetic peak of each magnetic pole. c) obtaining a roller-shaped molded product in which the magnetic powder at the center of the magnetic powder is oriented substantially parallel in response to the substantially parallel magnetic flux generated from each of the magnetic pole pairs; c) the roller-shaped molded product obtained in the step; The method is characterized by comprising a step of magnetizing so that adjacent magnetic poles are different from each other. Note that the magnetization step c) is performed by directly magnetizing the roller-shaped molded product obtained in step b) so as to obtain the desired magnetic pole arrangement, or by magnetizing the roller-shaped molded product obtained in step b). This can be done by once demagnetizing the item and then re-magnetizing it to obtain the desired magnetic pole arrangement. Note that when demagnetization is not performed in the magnetization step b), there is an advantage that the demagnetization step can be omitted. In addition, if a large, expensive, and powerful magnetizing device is required to directly magnetize the roller-shaped molded product obtained in step a), a method of demagnetizing and then re-magnetizing is used. This is useful in that good magnetic properties can be obtained in the final product without using a powerful magnetization device. When magnetizing a roller-shaped molded product, for example, as shown in Figure 6, the magnetic pole and the magnetization flux are aligned so that the magnetic flux for magnetization is applied along the orientation of the magnetic powder. Magnetization is performed by aligning the magnetic poles. Hereinafter, the magnet roller of the present invention will be explained in more detail by mentioning its manufacture. 2 to 4 and 6 schematically show each step of the manufacturing example, and FIG. 8 schematically shows the mold used in the manufacturing. Further, FIGS. 9 and 10 illustrate a conventional magnetic roller. Figure 2 is a drawing of the cavity in the mold used in the manufacturing example. In the figure, 1 and 4 are magnetic poles made of ferromagnetic material facing each other with the cavity in between. This is for guiding the magnetic flux from the magnetic field generating coils shown at 24 and 18 in FIG. 8 through the molding machine platens shown at 25 and 20 to the mold cavity. Further, 7, 8, 9 and 10, 11, 12 are magnetic poles that are integrated with the magnetic poles 1 and 4 above,
They are arranged substantially facing each other across a cylindrical cavity space indicated by 14. That is, magnetomotive poles 7, 8, and 9 from which lines of magnetic force flow and final poles 10, 11, and 12, into which lines of magnetic force flow, are lined up facing each other.
2 form a magnetic pole pair, and each magnetic pole is arranged so that the line connecting 7 and 10, the line connecting 8 and 11, and the line connecting 9 and 12 are almost on the same plane and are almost parallel. . Here, each magnetic pole is constructed of a ferromagnetic material as is conventionally known. Also 2, 3,
5 and 6 are spacers made of non-magnetic material. When current is applied to the magnetic field generating coils 18 and 24 in the configuration shown in FIG. The magnetic pole 1 is divided into 7, 8, and 9 magnetic poles (magnetomotive poles), and the flow flows into the 14 cavities according to the permeance distribution between the gaps, as shown at 13 in Figure 2. The flow converges at magnetic poles 10, 11, and 12 (final magnetic poles). That is, magnetic fluxes that are substantially parallel to each other in the same direction are generated within the cavity except in the vicinity of each magnetic pole. The magnetic flux passes through the magnetic pole 4, passes through the stationary platen shown at 25 in FIG. 8, and passes through the tie bar shown at 19, forming a closed loop. With the magnetic flux forming a closed loop as described above, when molten resin magnet material (ferromagnetic powder and binder) is injected into the 14 cavities, magnetic powder 15
The orientation of the magnetic field occurs according to the flow of the magnetic field lines shown in FIG. Since the lines of magnetic force spread within the cavity as shown in FIG. 2 and converge at the magnetic pole portion, the magnetic powder is also oriented in a converged state at the magnetic pole portion as shown in FIG. 3. Because of this orientation, the magnetic powder inside the molded product is effectively used and the lines of magnetic force are concentrated at desired positions of the molded product, so that a magnetic roller with a high surface magnetic flux density and strong magnetic force can be obtained. When the magnetic powder is cooled and solidified while maintaining its orientation as shown in FIG. 3, and taken out, a molded article shown in FIG. 4 is obtained. At this time, the distribution of surface magnetic flux density of the molded product shown in FIG. 4 becomes as shown in the upper part of FIG. 5. Next, the molded product shown in Fig. 4 was demagnetized by a conventionally known method, and the orientation was fixed as it was.
Only the magnetism is removed. Next, as shown in FIG. 6, the molded product as shown in the magnetized state shown in FIG. 1 is obtained by sequentially re-magnetizing it using a magnetizer mainly consisting of a yoke 16 and a magnetizing coil 17. The distribution of surface magnetic flux density at this time is shown in the lower part of FIG. Since the distance between the N and S poles of each magnetic pair of the molded product is different, in order to make the magnetic peaks of all the poles on the circumferential surface the same, it is necessary to change the material or cross-sectional area of the yoke of the magnetizer. (or by changing the magnitude of the current used)
The number of oriented ferromagnetic powders may be adjusted by changing the width of the portion where ferromagnetic powders are oriented between the north and south poles. Alternatively, the magnitude of the magnetic peak may be intentionally varied by adjusting the number of oriented ferromagnetic powders. The reason why magnetization is easily and reliably carried out using the magnetizer shown in Figure 6 is that the orientation in the molded product follows the flow of the magnetic field lines between the north and south poles, as shown in Figure 1. This is because the magnetic pairs are independent and clearly defined, and it is unlikely that a clear magnetic peak can be obtained with a conventional bipolar alignment product as shown in FIG. Four-pole and six-pole plastic magnetic rollers were prepared in the same manner as described above, and evaluated. Note that the orientation of the four poles was performed as shown in FIG. Rating is maximum surface magnetic flux density 900
[G] Compare the above with the typical specifications generally required for a developing roller for a copying machine, which is 60% or less width at half-life. The half-life time widths are A and B shown in Figure 12.
It is expressed by the following formula using . Width at half-life = (A/B) x 100 [%] (The larger this value is, the wider the waveform is.) As test 1, the 4-pole magnetic roller of the present invention, the conventional polar anisotropically oriented product, and the 2-pole The oriented products were tested, and as Test 2, the 6-pole magnetic roller of the present invention, the conventional polar anisotropically oriented product, and the bipolar oriented product were tested, and the results are shown in Tables 1 and 2.
All samples were made using a well-known plastic magnet material mixed with 90wt% strontium ferrite, and the mold temperature was 110%.
Two types of magnetic rollers with a diameter of 20 mm and 14 mm were manufactured by injection molding at a molding temperature of 280 °C.

【table】

〔Effect of the invention〕

As explained above, the magnetic roller of the present invention has excellent performance because the magnetic peak of the surface magnetic flux density is sharp, that is, the width at half-life is small, and the value of the surface magnetic flux density is large. In addition, the magnetic powder in the center part also contributes to the generation of magnetic force, and the diameter can be made as small as there is enough magnetic force. Furthermore, the equipment used for manufacturing may be small and simple.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of the magnetic roller after magnetization, FIG. 2 is a sectional view of the vicinity of the cavity of the mold used for manufacturing the magnetic roller of the present invention,
Fig. 3 is a cross-sectional view of the resin magnet material injected and oriented into the cavity, Fig. 4 is a cross-sectional view of the magnet roller after being removed from the mold, and Fig. 5 is a graph of the magnetic flux distribution on the circumferential surface of the magnet roller ( (The upper part of Figure 5 shows the magnetic flux distribution after demolding, and the lower part shows the magnetic flux distribution after magnetization.) Figure 6 is a schematic diagram showing re-magnetization using a magnetizer, and Figure 7 The figure is a cross-sectional view of the magnetic field injection molding device with four magnetic poles in Figure 3, Figure 8 is a schematic diagram showing the magnetic field injection molding device and mold part used in the manufacturing example, and Figure 9 is a conventional 2-pole model.
A schematic diagram for explaining polar orientation, FIG. 10 is a sectional view of a magnet roller obtained by demagnetizing and remagnetizing a bipolar oriented product, FIG. 11 is a sectional view of a polar anisotropically oriented product, and FIG.
The figure is a diagram for explaining the width at half-life, and FIG. 13 is a partial view of the magnetic roller of the present invention installed in a developing machine. 1, 4... Magnetic pole, 2, 3, 5, 6... Magnetic pole (non-magnetic material), 7, 8, 9... Magnetic pole (magnetic pole), 10,
11, 12... Magnetic pole (final magnetic pole), 13... Flow of magnetic flux (magnetic field lines), 14... Cavity in the mold, 15... Magnetic powder, 16... Yoke, 17...
Magnetizing coil, 18, 24...magnetic field generation coil,
20...Movable side molding machine platen, 21...Fixed side mold, 23...Movable side mold, 25...Fixed side molding machine platen, 26, 27, 28...Magnetic pole.

[Claims]

1 In a case where a superconducting winding and a quench promotion heater are installed on a winding frame having flanges at both ends of the inner shell, the coil frame is divided into two or more pieces at least in the circumferential direction with a spacer on the inner surface of both flanges. A superconducting magnet characterized in that a circular plate-shaped quench promoting heater is disposed, and a superconducting winding is further wound around the outer periphery of an inner shell on the inner surface of the quench promoting heater with an insulating member interposed therebetween.

Claims (1)

The magnetic poles are arranged such that straight lines connecting the magnetizing pole and the final magnetizing pole in each pair of magnetic poles are substantially parallel to each other on the cross section, and adjacent magnetic poles have different magnetisms, and the magnetic powder is It is oriented in a direction that converges toward the center of the magnetic peak of each magnetic pole in the peripheral part of the cross section, and is oriented almost parallel to a straight line connecting the magnetizing pole and the final magnetizing pole of each magnetic pole pair in the central part of the cross section. A method for manufacturing a magnetic roller oriented so that the magnet roller is formed, the method comprising: a) having a cavity for molding the magnetic roller, sandwiching the cavity at the outer circumference of the axial cross section of the cavity, and forming one of the magnetic rollers; A magnetizing pole is arranged on the outer periphery, and a final magnetizing pole that pairs with the magnetizing pole is arranged on the other outer periphery, and the starting and final magnetizing poles of each pair of magnetic poles are arranged so that lines of magnetic force passing through the center of the cavity are almost parallel. a) a resin material containing magnetic powder for magnetic roller molding is injected into the mold, and the magnetic powder in the resin material is arranged on the outer periphery of the cavity; Under magnetic orientation by the magnetic poles, the magnetic powder near the starting and ending poles in the cavity are oriented in a direction converging toward the center of the magnetic peak of each magnetic pole, and the magnetic powder in the center of the cavity is c) obtaining a roller-shaped molded product oriented substantially parallel in response to the substantially parallel magnetic fluxes generated from each pair of magnetic poles; c) so that adjacent magnetic poles of the roller-shaped molded product obtained in the step are different; 1. A method for manufacturing a magnetic roller, comprising the step of magnetizing the roller.