JP4761035B2 - Magnet roll - Google Patents

Description

  The present invention relates to a magnet for a magnet roll that is mounted on a copying machine, a printer, or the like, and more particularly to an improvement in a magnet for a magnet roll having a substantially sectoral cross section that is bonded to a shaft. Moreover, this invention relates to the magnet roll comprised using the said magnet for magnet rolls. Furthermore, this invention relates to the metal mold | die for shape | molding the said magnet for magnet rolls.

  As a developing roll for visualizing an electrostatic latent image formed on a photosensitive drum such as a copying machine or a printer, a magnet roll having a magnet on the peripheral surface of a shaft is widely used. For example, in the jumping method, toner is blown out by the magnetic force of a magnet roll, and this is adhered to the photosensitive drum. In the brush system, a mixture of magnetic powder (carrier) typified by iron powder and toner is conveyed to a photosensitive drum by the magnetic force of a magnet roll. In either case, toner is supplied to the photosensitive drum by the magnetic force of the magnet roll and fixed on paper or the like, whereby characters, images, etc. corresponding to the electrostatic latent image are printed and visualized.

  Various types of magnet rolls are known. For example, as the magnet roll for the jumping method, there are those composed of four poles, a pumping pole, a transport pole, a developing pole, and a collecting pole. As a magnet roll for a brush system, there is one composed of five poles obtained by adding a peeling pole to the aforementioned four poles.

  And the magnet for magnet rolls which produces these 4 poles or 5 poles magnetic poles is divided roughly into the following two types. First, a hollow cylinder is integrally formed around the shaft, or a hollow cylinder is formed, and the shaft is fixed to the center. Second, for example, a mixture of magnet powder and a binder is formed into a fan-shaped cross section. The magnet roll is configured by adhering a plurality of magnets for a magnet roll having a sectional fan shape around the shaft.

  However, in the case of an integrated structure such as the former, it is difficult to form a plurality of magnetic poles and it is difficult to cope with the characteristics. As miniaturization of copying machines and printers progresses, the diameter of the magnet roll tends to decrease, and a high magnetic force is required. In particular, the development electrode (main electrode) used for conveying the toner to the photosensitive drum has severe requirements. With the magnet for a magnet roll having an integrated structure, it is almost impossible to form a developing electrode that can sufficiently meet the requirements.

  Under these circumstances, various types of magnet rolls having the latter structure (a structure in which a plurality of fan-shaped magnet roll magnets are bonded together) have been proposed and improved (for example, Patent Document 1 and Patent Document 2). See).

  For example, Patent Document 1 proposes a magnet for a magnet roll (magnet piece) that defines a contact area of the outer diameter of the shaft and is processed to be applied with high accuracy. Specifically, a magnet piece in which the entire arc on the inner peripheral side of the magnet piece contacts the outer periphery of the shaft, and 0.01% to 25% of the arc length on the inner peripheral side of the magnet piece contacts the outer periphery of the shaft. Combined with a magnet piece.

Patent Document 2 proposes a structure in which a side surface of a magnet for a magnet roll and a part of a shaft contact surface are processed to provide an adhesive reservoir. Specifically, in a magnet roller formed by bonding a plurality of magnet pieces, the width is 1 to 10 mm from the end in the longitudinal direction with respect to at least one surface selected from the side surface and the inner peripheral surface of the magnet piece. At least one magnet piece provided with a substantially radial groove having a depth of 0.5 mm to 5.0 mm and a depth of 0.5 mm to 2.0 mm is bonded and fixed to the shaft.
JP 2003-163112 A JP 2004-273960 A

  By the way, in a magnet roll having a structure in which a plurality of fan-shaped magnet roll magnets are bonded together, there are many points to be improved such as prevention of adhesive sticking out, securing of bonding accuracy, and securing of adhesive strength. In order to solve these problems, the invention described in Patent Document 1 and the invention described in Patent Document 2 have been proposed. For example, in the invention described in Patent Document 1, one of magnets for a magnet roll is proposed. It is necessary to greatly change the shape of the part, and a plurality of types of molds are required for molding, which makes the manufacturing complicated and may cause a decrease in yield. Moreover, in the magnet piece which made the range which contacts a shaft 0.01% or more and 25% or less of circular arc length, the contact area with respect to a shaft is small, and it may become difficult to maintain a stable attachment state. Furthermore, if the shape of the magnet piece is greatly changed, there is a possibility that it may become an obstacle to securing the magnetic characteristics of the magnet piece, and there is a possibility that the performance improvement of the magnet roll may be hindered. Furthermore, when a magnet for a magnet roll having a small contact area with the shaft as described in Patent Document 1 is produced by injection molding or extrusion molding, the die corresponding to the contact portion is particularly easily worn. As a result, the dimensional accuracy of the magnet for the magnet roll, particularly the accuracy in the height direction, tends to become unstable, and it becomes difficult to obtain the stability of the magnetic properties of the magnet roll. Also, when the shape of the shaft contact part is produced by post-processing such as grinding, the amount of grinding becomes considerably large, requiring labor and time, and if the grinding powder is not sufficiently removed after grinding, It also becomes.

  On the other hand, the invention described in Patent Document 2 provides a technique for reducing the overflow of the adhesive onto the surface of the magnet roller, and a certain degree of effect can be expected in terms of preventing the adhesive from protruding. However, no consideration is given to the bonding accuracy, and it must be said that this is insufficient. When attaching magnet roll magnets to the shaft, if there is a slight deviation in the dimensions of the molded magnet roll magnets, the magnet roll magnets will stick together due to the wrinkling, making accurate assembly difficult, Inconveniences such as insufficient adhesion strength of the floated magnet and easy peeling occur.

  The present invention has been proposed in view of the above-described conventional situation, can ensure the accuracy of bonding to the shaft, can ensure adhesive strength, and can prevent the adhesive from protruding. It aims at providing the magnet for possible magnet rolls, and also aims at providing a magnet roll. Further, the present invention does not require a significant change in shape, is advantageous in terms of productivity, magnetic characteristics, and the like, and is also effective in preventing mold wear and product contamination, and a magnet for magnet rolls. An object is to provide a magnet roll. Still another object of the present invention is to provide a molding die capable of molding a magnet for a magnet roll that can secure the bonding accuracy and adhesive strength.

In order to achieve the above-mentioned object, the magnet roll of the present invention is a magnet roll in which a plurality of magnet roll magnets having a sectional fan shape divided in the circumferential direction are bonded and integrated around the shaft. At least one of the plurality of magnet roll magnets has an arc surface along the peripheral surface of the shaft, the arc surface abuts on the peripheral surface of the shaft having a substantially circular cross section, and the arc surface The shaft side edge along the longitudinal direction of the shaft on both sides is chamfered, and further, a notch is formed at the outer circumferential side edge along the longitudinal direction of the shaft.

  In the present invention, as described above, the shaft side edge of the magnet for magnet roll is chamfered. And when the magnet for magnet rolls is adhere | attached on the surrounding surface to a shaft, some space is formed in this chamfering process part, and it functions as a buffer which absorbs the dimensional error of the magnet for magnet rolls. Therefore, even when a slight error occurs in the size of the magnet for the magnet roll due to wear of the mold or the like, an accurate bonding state is realized, and the magnet for the magnet roll does not float.

  The space also functions as a space for accommodating the adhesive, and when the magnet for the magnet roll is bonded, the excessive adhesive is accommodated in the space, and inconveniences such as the adhesive sticking out are eliminated. In addition, since the adhesive is accommodated in the space, it contributes to the improvement of the adhesive strength, and sufficient adhesive strength is secured in the adhesion of the magnet for the magnet roll to the shaft.

  Furthermore, in the magnet for magnet rolls of the present invention, it is only necessary to have the chamfered shape. For example, it is not necessary to greatly change the shape of the magnet for magnet roll, so that productivity and magnetic characteristics are not deteriorated. When the shape of a part of the magnet for the magnet roll is largely changed as in the invention described in Patent Document 1, a plurality of types of molds are required, which causes a decrease in productivity. Then, since only the chamfering process is performed on the edge of all magnet roll magnets, it is not necessary to change the mold according to the shape. In addition, since only a few magnet parts are deleted, the magnetic characteristics are hardly affected.

  As described above, the magnet for a magnet roll according to the present invention has advantages in terms of securing bonding accuracy, preventing adhesive sticking out and securing adhesive strength, and suppressing reduction in productivity and magnetic properties. In addition, it is also useful for wear countermeasures. The magnet for a magnet roll is formed by, for example, extrusion molding or injection molding. However, when the magnet to be molded has corners, mold wear, product contamination, and the like are likely to occur. In particular, when the shaft contact area is small, such as the magnet for magnet roll described in Patent Document 1, the wear of the mold at the corresponding part is particularly large and disadvantageous. Since the magnet for a magnet roll of the present invention has a chamfered shape as described above, a mold for molding used in, for example, extrusion molding or injection molding can also be chamfered, which can cause mold wear and product contamination. Occurrence is suppressed.

  In the magnet for a magnet roll according to the present invention, the shaft side edges along the shaft longitudinal direction on both sides of the arcuate surface are chamfered, and the outer edges are also cut along the shaft longitudinal direction. If a notch is formed to have a chamfered shape, there is no corner at the corresponding position, which is more preferable from the viewpoint of mold wear and contamination. This is defined in the invention described in claim 6 of the present application, and further characterized in that a notch is formed in the outer peripheral side edge along the longitudinal direction of the shaft.

  When manufacturing the magnet for the magnet roll, it is possible to perform chamfering as post-processing in order to obtain the chamfered shape, but this is disadvantageous from the viewpoint of manufacturing cost and production capacity because post-processing increases the number of processes. Moreover, there is a possibility that problems such as processing powder causing foreign matter may occur. From such a viewpoint, it is advantageous to give a chamfered shape to the magnet for magnet roll at the time of molding. The molding die according to claim 9 of the present application is for giving a chamfered shape to the magnet for magnet roll at the time of molding, has a substantially fan-shaped cross section, and is bonded to the peripheral surface of the shaft to form a magnet roll. A magnet mold for forming a magnet for a magnet roll, having a circular arc surface corresponding to the peripheral surface of the shaft, and a portion corresponding to a shaft side edge along the longitudinal direction of the shaft on both sides of the circular arc surface Has a chamfered shape.

  According to the present invention, it is possible to ensure the bonding accuracy of the magnet for the magnet roll to the shaft, and to prevent the adhesive from protruding while ensuring the adhesive strength. Further, according to the present invention, since it is not necessary to greatly change the shape of the magnet for the magnet roll, the magnetic characteristics and the like are hardly deteriorated, mold wear and product contamination are prevented, and productivity is improved. It is also possible.

  Hereinafter, embodiments of a magnet for a magnet roll and a magnet roll to which the present invention is applied will be described in detail with reference to the drawings.

  First, the structure of the developing roll in which the magnet roll is incorporated will be described. As shown in FIGS. 1 to 3, the developing roll 1 is configured by incorporating a magnet roll 3 in a cylindrical sleeve 2. The sleeve 2 is formed of aluminum, for example, and is formed as a cylindrical body having a length sufficient to accommodate the magnet roll 3. Further, a gap having a predetermined interval is formed between the sleeve 2 and the inner peripheral surface and the outer peripheral surface of the magnet roll 3 accommodated therein.

  The magnet roll 3 is configured by, for example, arranging a plurality of magnet roll magnets, here, magnet roll magnets 5, 6, 7, 8, 9 divided into five around the shaft 4 made of metal, and bonding and fixing them. Has been. Each of the magnet roll magnets 5 to 9 has a substantially sectoral cross-sectional shape, and by sticking them around the shaft 4, a magnet body having a cylindrical shape as a whole is configured.

  Each of the magnet roll magnets 5 to 9 is formed by extruding or injection molding a mixture containing a binder (plastic or rubber) and magnet powder. Here, the type of the binder is not particularly limited, and specifically, polyamide resin (nylon 6, nylon 12, etc.), polyolefin resin such as polypropylene and polyethylene, polycarbonate resin, nitrile rubber (NBR), chloroprene rubber Synthetic rubber, natural rubber or the like can be used. Examples of the magnet powder include ferrite magnet powder (for example, Sr-based ferrite powder and Ba-based ferrite powder) and rare earth metal magnet powder (for example, SmCo-based, NdFeB-based, SmFeN-based, etc.). What is necessary is just to select according to the characteristic requested | required from these.

  The magnet roll magnets 5 to 9 are each magnetized in the radial direction, and the outer peripheral surface side is set to the N pole or the S pole, and the N pole and the S pole are arranged alternately on the outer peripheral surface of the magnet roll 1. It is pasted together. These magnet roll magnets 5 to 9 function as a pumping electrode, a layer regulating electrode, a conveying electrode, a developing electrode, and a peeling electrode, and are attached to the sleeve 2 in a predetermined arrangement.

  The shaft 4 is made of a high-strength material such as metal and is longer than the magnet roll magnets 5 to 9 attached to the peripheral surface. Therefore, the magnet roll magnets 5 to 9 are attached to the peripheral surface. When attached, both ends are exposed. Both ends of the exposed shaft 4 are rotatably inserted into flanges 10 and 11 provided at both ends of the sleeve 2 through bearings 12 and 13. One end side of the shaft 4 extends through the flange 10 to the outside, but the other end side is abutted against the flange 11, and a shaft portion 11 a is provided on the flange 11 so as to extend the shaft 4. ing.

  Here, when the shaft portion 11 a is rotationally driven from the right flange 11 side in FIG. 3, the rotation is transmitted to the sleeve 2 via the flange 11. Therefore, the right side flange 11 is called a drive side flange and is formed of a nonmagnetic material (for example, aluminum, aluminum alloy, stainless steel, etc.) having excellent wear resistance. On the other hand, the left flange 10 in FIG. 3 is called a driven flange and has a function of holding the magnet roll 3 in the sleeve 2 and is formed of, for example, aluminum, aluminum alloy, stainless steel, resin material, or the like. The

  The above is the schematic configuration of the developing roll, but in the magnet roll of the present invention used for the developing roll, at least one of the magnet roll magnets 5 to 9 has a shaft-side edge that is chamfered. This is a major feature. Then, next, the shape of the magnets 5-9 for magnet rolls is explained in full detail.

  4 shows the shape of a magnet for magnet roll (here, magnet 5 for magnet roll) in which the shaft side edge is chamfered, (a) is a perspective view, (b) is a front view, (C) is a bottom view.

  As described above, the magnet 5 for the magnet roll is formed in a long shape so that the cross section has a substantially fan shape, and the inner peripheral surface 5a and the outer peripheral surface 5b are each an arcuate curved surface. Particularly, the inner peripheral surface 5 a is an arc surface having a curvature substantially equal to the curvature of the outer peripheral surface of the shaft 4. When the magnet roll magnet 5 is bonded to the shaft 4, the inner peripheral surface 5 a is the shaft 4. The surface contact state is made in a form along the outer peripheral surface.

  Since the magnet roll magnet 5 has a substantially sectoral cross section as described above, the longitudinal direction of the magnet roll magnet 5 (that is, the length of the shaft 4) is provided on both sides of the inner circumferential surface 5a and the outer circumferential surface 5b, which are arcuate surfaces. In the present invention, the edge part on the shaft 4 side (that is, the edge part along both sides of the inner peripheral surface 5a) is chamfered (here, so-called C chamfering). For example, a C surface 5c is formed.

  By forming the C surface 5c, it becomes possible to perform bonding with high accuracy, and there is no problem of floating. It is also effective in preventing the adhesive from sticking out and securing the adhesive strength.

  FIG. 5 shows a state in which C surfaces 5 c to 9 c are formed on the shaft 4 side edges of the magnet roll magnets 5 to 9 and bonded to the shaft 4. By forming the C surfaces 5c to 9c, a space s is formed in a portion where the magnet roll magnets 5 to 9 on the circumferential surface of the shaft 4 are in contact with each other. Therefore, for example, even when a dimensional deviation occurs in any of the magnets 5 to 9 for the magnet roll, it is absorbed by the space s and does not float when pasted. Further, the space s also functions as an adhesive reservoir, and excess adhesive is accommodated in the space s so that the adhesive does not protrude. At the same time, the adhesive accommodated in the space s exerts an adhesive force between the magnet roll magnets 5 to 9 and the shaft 4 to ensure a sufficient adhesive force.

  The shape of the magnet 5 for the magnet roll is not limited to the above, and the shape of the outer peripheral surface 5b is arbitrary as long as the surface on the shaft 4 side (inner peripheral surface 5a) is an arc surface. For example, the outer peripheral surface 5b may be a straight flat surface or a shape having irregularities. Even when the outer peripheral surface 5b is an arc surface, the arc shape of the inner peripheral surface 5a and the arc shape of the outer peripheral surface 5b do not necessarily have to be concentric. For example, if the center of the arc of the inner peripheral surface 5a and the center of the arc of the outer peripheral surface 5b are set at different positions, these arcs are not concentric circles. In any case, the same effect as described above can be obtained by forming the C surface on the end edge on the shaft 4 side. For example, the same applies to the case where the arc center C1 of the inner circumferential surface 5a of the magnet roll magnet 5 and the arc center C2 of the outer circumferential surface 5b are shifted to form a non-concentric circle as described above. A similar effect can be obtained by forming the C surface 5c along both sides of the surface 5a.

  In the C surfaces 5c to 9c, it is preferable to set the chamfering amount appropriately. When the chamfered shape is a C chamfered shape and the C surfaces 5c to 9c are formed as described above, the dimension t of the C surface 5c (to 9c) shown in FIG. 4B is set to 0.2 mm to 1.5 mm. It is preferable to set to. If the dimension t is less than 0.2 mm, a sufficient effect may not be obtained. On the other hand, if the dimension t exceeds 1.5 mm, there is a risk of reducing accuracy during bonding and assembly, and further, the deformation amount (reduction amount) of the magnets 5 to 9 for the magnet roll increases. There is concern about a decrease in magnetic properties.

  Further, the chamfering shape is not limited to the C chamfering shape, and for example, as shown in FIG. 7, it is possible to form an R chamfering shape and form the R surface 5d. In this case, the chamfering amount may be set in a range in which the radius of curvature r of the R surface 5d is 0.2 mm to 1.5 mm. Even in the case of the R chamfered shape as described above, the same effect as in the case of the C chamfered shape can be obtained.

  Whether the chamfering shape is the C chamfering shape or the R chamfering shape is arbitrary, but when the central angle θ shown in FIG. If it is small, it is preferable to use the R plane. For example, it is preferable to use the C plane when the central angle θ exceeds 50 ° and the R plane when it is less than 50 °. When C chamfering is performed on the magnet roll magnets 5 to 9 having a small central angle θ, the dimension of the arc surface between the C surfaces 5c becomes too small, and may not be stably attached to the shaft 4. . In addition, in the magnetic pattern of the magnets 5-9 for the magnet roll, when the position of the peak of the magnetic field is deviated from the center line of the outer peripheral surface, or when the shape of the magnets 5-9 for the magnet roll is asymmetrical, One may be the C plane and the other the R plane.

  Further, as shown in FIG. 8, notches 5e may be formed not only on the end edge on the shaft 4 side of the magnet 5 for magnet roll but also on the end edge on the outer peripheral surface 5b side. This outer peripheral surface edge is a part where the mold wear is large like the shaft side edge, and when attaching the magnet for the magnet roll to the shaft, it is not the part of the shaft side edge, but the part where accuracy is required. Because. By forming the notch 5e on the outer peripheral surface 5b side, it becomes easier to ensure the accuracy at the time of attachment. However, if the notch amount T of the notch 5e becomes too large, the magnetic pattern on the outer peripheral surface of the magnet roll 3 may be adversely affected. Therefore, the notch amount T is preferably 3 mm or less.

  The C surface 5c, the R surface 5d, and the notch 5e may be formed by chamfering a die during extrusion molding or injection molding of the magnet 5 for magnet roll, or a magnet roll. After the magnet 5 is formed, it may be formed by chamfering later by machining (cutting or the like). However, when taking measures against wear, the former (formed by chamfering the mold) is preferable. If the mold used for molding is chamfered, the wear of the mold can be suppressed and the product contamination generated at the edge portion can also be suppressed.

  FIG. 9 shows an example of a molding die used for molding the magnet roll magnet. The molding die 11 of this example is an extrusion molding die, and by extruding a molding material (a mixture containing magnet powder and a binder) through the molding space 12, the molding die 11 corresponds to the shape of the molding space 12. A magnet for a magnet roll having a cross-sectional shape (for example, a substantially fan-shaped cross section) is formed.

  It is also possible to magnetize or orient the outer peripheral surface during the molding. In that case, the molding die 11 may be made of a non-magnetic cemented carbide or stainless steel, a magnetic pole may be disposed above it, and a magnetic field may be applied. It is shaped so that the peak of the magnetic field is located at the position of the alternate long and short dash line in the figure where the distance from the magnetic pole is closest, that is, at the approximate center of the sector.

  In the molding die 11, if the edge portions 13a and 13b on both sides of the shaft-side arcuate surface 13 are chamfered, for example, as shown in FIG. The corresponding edge portion is chamfered. Further, as shown in FIG. 9 (b), if the edge portions 14a and 14b on both sides of the outer circumferential surface side arc surface 14 are chamfered so as to have a chamfered shape, the corresponding edge portion of the magnet for magnet roll formed in the same manner. Becomes a chamfered shape.

  The molding is not limited to molding in which the magnetic field peak is located in the center, but may be performed so that the magnetic pattern is asymmetrical, and the length and shape of chamfers and notches are different on the left and right. May be.

  Next, specific examples of the present invention will be described based on experimental results.

<Comparative Example 1>
A magnet for magnet rolls was produced by extruding a mixture containing 90% by mass of ferrite magnet powder and 10% by mass of NBR. The produced magnet for magnet roll has a length of 300 mm and a cross-sectional shape of a substantially sector shape with a central angle θ = 60 °. At the time of molding, in the molding die having the same configuration as shown in FIG. 9, the edge portions 13a and 13b and the edge portions 14a and 14b were not chamfered, and extrusion molding was performed. Therefore, the magnet for magnet rolls molded in this example is not chamfered and corresponds to a comparative example. The shape of the magnet for magnet rolls in this example is shown in FIG. In the figure, the inner R indicates the radius of the inner circular arc surface, and the outer R indicates the radius of the outer circular arc surface (the same applies hereinafter).

<Comparative example 2>
A magnet for a magnet roll was produced by extruding the same mixture as in Comparative Example 1. The produced magnet for magnet roll has a length of 300 mm and a cross-sectional shape of a sector shape with a central angle θ = 45 °. During molding, extrusion molding was performed in a molding die having the same configuration as that shown in FIG. 9 without forming the edge portions 13a, 13b, 14a, and 14b of the molding space into chamfered shapes. Therefore, the magnet for magnet rolls molded in this example is not chamfered and corresponds to a comparative example. The shape of the magnet for magnet rolls in this example is shown in FIG.

<Example 1>
A magnet for a magnet roll was produced by extruding the same mixture as in Comparative Example 1. The produced magnet for magnet roll has a length of 300 mm and a cross-sectional shape of a substantially sector shape with a central angle θ = 60 °. However, at the time of molding, the molding die was partially changed from that of the comparative example, and the edge portions 13a and 13b were made horizontal as shown in FIG. 9A, and the C chamfered shape shown in FIG. The chamfering amount t in the C chamfered shape was 0.7 mm. The shape of the magnet for magnet rolls in this example is shown in FIG.

<Example 2>
A magnet for a magnet roll was produced by extruding a mixture similar to that in Comparative Example 1 and molding the mixture. The produced magnet for magnet roll has a length of 300 mm and a cross-sectional shape of a substantially sector shape with a central angle θ = 45 °. In molding, a molding die having the same configuration as that shown in FIG. 9A was used, but the edge portions 13a and 13b were formed as R surfaces, and the shaft side R chamfered shape was adopted. In the R chamfered shape, the radius of curvature r of the R surface was 0.3 mm. The shape of the magnet for the magnet roll of this example is shown in FIG.

<Example 3>
A magnet for a magnet roll was produced by extruding a mixture similar to that in Comparative Example 1 and molding the mixture. The produced magnet for magnet roll has a length of 300 mm and a cross-sectional shape of a substantially sector shape with a central angle θ = 60 °, but the inner and outer peripheral surfaces are non-concentric. For molding, a molding die shown in FIG. 9B (however, the center of the arc of the inner peripheral surface and the position of the center of the arc of the outer peripheral surface are different) is used. Was made into C chamfering shape. The chamfering amount t in the C chamfered shape is 1.5 mm. Further, a notch having a length of 1.5 mm was provided. The shape of the magnet for the magnet roll of this example is shown in FIG.

<Evaluation>
The produced magnet roll magnet was attached to the entire circumference of the shaft to produce a magnet roll. That is, in Comparative Example 1, Example 1 and Example 3 with a central angle of 60 degrees, six magnet roll magnets are used, and in Comparative Example 2 and Example 2 with a central angle of 45 degrees, eight magnets are used. A roll magnet was attached to the entire circumference to obtain a magnet roll. In addition, the magnetic poles on the surfaces of the adjacent magnet rolls were arranged so as to alternate with N, S, N. Using the produced magnet roll, the adhesive protruded and the bonding accuracy was examined. In addition, the life of the mold when the magnet for magnet roll was extruded was also examined.

As shown in FIG. 11A, the protrusion of the adhesive was performed by attaching magnet magnets M for the magnet roll around the shaft S to produce 100 magnet rolls, and the protrusion of the adhesive B was confirmed visually. Table 1 shows the number of magnet rolls in which the protrusion was confirmed. First, the bonding accuracy was evaluated by the presence or absence of lifting. That is, 3 magnet roll magnets (Comparative Example 1, Example 1 and Example 3) or 4 magnets (Comparative Example 2 and Example 2) before bonding were adsorbed to each other by the magnetic force of the magnet for magnet roll. . After making two sets of them, the two sets of magnets M for magnet rolls were adsorbed across the shaft S as shown in FIG. In that state, it was visually observed from the end portion, and the one in which the lift P of the magnet M for the magnet roll was not confirmed was regarded as acceptable. 100 magnet rolls were produced, and the number of passed magnet rolls is shown in Table 1. Next, a self-weight drop test was performed on the magnet rolls that passed the lifting evaluation. In the dead weight drop test, as shown in FIG. 11 (c), the shaft S is suspended in the vertical direction, and in this state, it is checked whether the magnet M for the magnet roll falls from the shaft S under its own weight. Those were accepted, and the numbers are shown in Table 1.

  Further, with respect to the magnet roll that passed the dead weight drop test, the magnet M for the magnet roll was adhered to the shaft S, and the deflection amount of the outer peripheral surface was measured with an optical displacement meter while the shaft S was rotated. Table 1 shows the number of magnet rolls that passed with an amount of shake of 400 μm or less. The mold life is visually observed for deposits (magnet pieces) on the magnet for magnet roll after molding, and in the molding of the last 100 magnet roll magnets, more than half (50) deposits exist. The total number of magnet roll magnets produced up to this point was defined as the mold life. The results are shown in Table 1.

  As is apparent from this table, it can be seen that by chamfering the shaft side edge of the magnet for the magnet roll, protrusion of the adhesive and lifting of the magnet for the magnet roll are eliminated, and a highly accurate magnet roll can be obtained. . Moreover, the mold life is greatly improved by the chamfering process.

It is the schematic diagram which looked at the image development roll from the center cross-section direction. It is a disassembled perspective view of a magnet roll. It is a schematic sectional drawing of a developing roll. The example of the shape of the magnet for magnet rolls is shown, (a) is a perspective view, (b) is an end view and an enlarged view of a chamfered part, (c) is a bottom view. It is the schematic diagram which looked at the magnet roll which bonded the magnet for magnet rolls shown in FIG. 4 from the center cross-section direction. It is an end elevation which shows an example of the magnet for magnet rolls which made the outer peripheral surface and the inner peripheral surface non-concentric and formed C surface. It is the end elevation which shows an example of the magnet for magnet rolls made into R chamfering, and the enlarged view of a chamfering part. It is an end elevation which shows an example of the magnet for magnet rolls which carried out the chamfering process of the shaft side, and provided the notch in the outer peripheral side. It is an end elevation which shows typically an example of a metallic mold, (a) shows the example which made the edge part of both sides of a shaft side circular arc surface into a horizontal surface, and made it chamfered, and (b) is an outer peripheral side arc. An example in which the edge portions on both sides of the surface are chamfered with a vertical surface is shown. (A)-(e) is a top view which shows the shape of the magnet for magnet rolls produced in each Example and the comparative example. It is a conceptual diagram which shows the evaluation method of the magnet roll produced by the Example and the comparative example, (a) protrudes of an adhesive agent, (b) floats, (b) shows an example of a self-weight drop test.

Explanation of symbols

1 developing roll, 2 sleeve, 3 magnet roll, 4 shaft, 5, 6, 7, 8, 9 magnet for magnet roll, 5a inner peripheral surface, 5b outer peripheral surface, 5c C surface, 5d R surface, 5e notch, 11 Mold for molding, 12 Molding space, 13a, 13b, 14a, 14b Edge part, 20 Magnet for magnet roll, 20a, 20b Notch

Claims (6)

A magnet roll in which a plurality of magnet roll magnets having a fan-shaped cross section divided in the circumferential direction are bonded around the shaft, and are integrated,
At least one of the plurality of magnet roll magnets has an arc surface along the peripheral surface of the shaft, the arc surface abuts on the peripheral surface of the shaft having a substantially circular cross section, and both sides of the arc surface The shaft side edge along the longitudinal direction of the shaft is chamfered,
Furthermore, the notch is formed in the outer peripheral side edge along a shaft longitudinal direction, The magnet roll characterized by the above-mentioned. The magnet roll according to claim 1, wherein the chamfered shape is a C chamfered shape . The magnet roll according to claim 2, wherein a chamfering amount in the C chamfered shape is 0.2 mm to 1.5 mm. The magnet roll according to claim 1, wherein the chamfered shape is an R chamfered shape. The magnet roll according to claim 4, wherein a radius of curvature of the R surface in the R chamfered shape is 0.2 mm to 1.5 mm. The magnet roll according to claim 1, wherein the cutout amount of the cutout is 3 mm or less.

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