JPH11165329A - Manufacture of magnet roll - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eliminate a problem due to a clearance generated between an outer surface of a slide die and an inner surface of a main mold by stabilizing a magnetic force in a lengthwise direction and reducing a warpage. SOLUTION: The magnet roll is formed by using a mold having a main forming die 5, an end forming die and a slide die. After the formation, the slide die is projected into a forming space, thereby removing the roll out of the mold. In this case, an injection cast resin magnet composition is cooled by a plurality of cooling blocks 16, 17, 18 and 19 disposed adjacent to a plurality of magnetic field orienting means 9 disposed at a predetermined interval along an outer periphery of the die 5 and adjacent to the plurality of a magnetic field orienting means 9 brought into contact with the outer periphery of the die 5, and brought into contact with an outer periphery of the die 5 to provide a temperature difference to the blocks 16, 17, 18 and 19.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a magnet roll used in an electrophotographic developing device such as a copying machine, a facsimile, a printer, and the like, and a magnet roll used for other purposes.

[0002]

2. Description of the Related Art When manufacturing a magnet roll,
In general, an injection molding method is used in which a resin magnet composition is injected into a split mold including a fixed mold and a movable mold that can be separated from the fixed mold to form a magnet roll. . However, in this method, in order to stabilize the magnetic properties in the longitudinal direction and reduce the warpage, the mold temperature is set to 110 to 130.
The temperature was set to ° C, and the temperature was gradually reduced. In spite of the fact that the cooling is performed over a long period of time in this way, a difference occurs in the amount of warpage of each compact, stabilizing the longitudinal magnetic force (zone magnetic force) necessary for high image quality, The effect is not enough to reduce the warpage.

Therefore, for example, as shown in Japanese Patent Application No. 8-335463 previously proposed by the present applicant, a cylinder provided with an injection port for injecting a molten resin magnet composition at one end. The magnetic force (zone magnetic force) in the longitudinal direction of the magnet roll formed by using a mold composed of a main mold having a cylindrical shape and a slide mold for forming a shaft movably disposed in the main mold. To stabilize and reduce warpage. However, in this proposed method, the clearance between the outer surface of the slide die and the inner surface of the main die greatly contributes to the coaxiality of the molded product, and galling occurs between these two dies, that is, the slide die and the main die. This causes practical problems such as generation of burrs and the like. The galling means that the sliding surface is scratched.

[0004] The above problem is caused by a change in the clearance between the outer surface of the slide die and the inner surface of the main mold due to thermal expansion, particularly when the mold temperature is high. In order to solve this, it is preferable to cool the main mold at 100 ° C. or lower. However, magnet rolls are often non-equipolar due to their required characteristics, and the volume of each cooling block arranged between the poles is different. Therefore, the cooling efficiency of the molded body having a larger contact area was higher as the molded body had a larger contact area, resulting in warpage and instability of the magnetic force in the longitudinal direction (zone magnetic force). For example, FIG. 12 shows a graph of the magnetic flux density distribution of the formed magnet roll, and the magnetic flux density fluctuates within the vertical range H in the longitudinal direction.

[0005]

SUMMARY OF THE INVENTION In view of the above situation, the present invention is intended to stabilize the magnetic force (zone magnetic force) in the longitudinal direction, reduce the warpage, and reduce the outer surface of the slide type. And a practical problem caused by a clearance generated between the mold and the inner surface of the main mold.

[0006]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides a resin magnet composition containing a magnetic powder and a binder as main components, which is injected and injected into a molding space formed by a mold. After applying a plurality of magnetic fields by a plurality of magnetic field orienting means, respectively, in the method of manufacturing a magnet roll to take out from the mold, as the mold, a main mold for forming a roll body of the magnet roll, An end forming die disposed at one end of the main forming die to form one of the shafts formed at both ends of the magnet roll; and an end forming die formed to form the other shaft. The magnet roll is formed using a slide mold slidably disposed in the main mold, and the magnet roll is formed by projecting the slide mold into the molding space after this molding. A plurality of magnetic heads arranged so as to be taken out of the mold, adjacent to the plurality of magnetic field orienting means arranged at predetermined intervals along the outer peripheral surface of the main mold, and in contact with the outer peripheral surface of the main mold. The cooling resin block is used to cool the resin magnet composition injected and injected, and to provide a temperature difference between these cooling blocks. Therefore, by cooling the main mold by the cooling block, the dimensional change of each part of the mold due to thermal expansion can be suppressed low, and in particular, a large change in the clearance between the outer surface of the slide mold and the inner surface of the main mold is suppressed. You can do it. Moreover, by providing a temperature difference to each cooling block, the cooling efficiency of the resin magnet composition cooled by the cooling block having a small contact area with the main mold can be increased, and the resin magnet composition can be spread over the entire area. It becomes possible to cool uniformly.

The cooling temperature of the cooling block is 100 ° C.
It is optimal to set the temperature difference between 2 and 10 ° C. below, and the cooling temperature of the cooling block having a small contact area with the main mold is lower than the cooling temperature of the cooling block having a large contact area. By setting, the resin magnet composition is uniformly cooled over the entire area.

[0008] By forming at least one of the cooling blocks from a non-magnetic material having a higher thermal conductivity than the magnetic-field-orienting member forming member, the cooling efficiency of the cooling block can be increased.

The cooling block forms a flow passage in which a cooling medium flows, and water that is easy to handle is used for the cooling medium.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 3 shows a magnet roll formed by injecting a resin magnet composition into a mold. This magnet roll 1 has a diameter reduced at both ends of a roll body 2 having a circular cross section. The shaft portions 3 and 4 are formed so as to protrude, and are integrally formed using a resin magnet composition. Although not shown, a cut-out portion for positioning or driving force transmission may be formed in the one shaft portion 3 or 4 or both shaft portions 3 and 4 for implementation. In addition, as the magnet roll 1, the roll part 2
The present invention can be similarly applied to a case where is not a cylinder but a polygonal column, or a case where the axis center of the roll portion 2 and the axis centers of the shaft portions 3 and 4 are intentionally decentered.

The resin magnet composition (hereinafter, referred to as a resin magnet) constituting the magnet roll 1 is mainly composed of a magnetic powder and a binder for bonding the magnetic powders together, and a silane for strengthening the bonding. A mixture containing a trace amount of a series or titanate type coupling agent, a lubricant to improve the flowability, a stabilizer to prevent the thermal decomposition of the binder, etc. It can also contain a flame retardant, reinforcing agent, etc. if necessary. In the magnetic powder, ferrite,
Rare earth system (SmCo system, NdFeB system), MnAIC
System, alnico system, SmFeN system, etc.
As the binder, a thermoplastic resin, a thermosetting resin, a low melting point alloy, or the like can be used.

The magnet roll 1 is used as a developing roll and a cleaning roll in an electrophotographic developing device such as a copying machine, a facsimile, a printer, and the like, but can be used for other purposes.

Next, the apparatus for manufacturing the magnet roll 1 will be described. As shown in FIGS. 1 to 4, a cylindrical fixed-side main forming die 5 for forming the roll body 2 of the magnet roll 1 is formed. An end forming die 6 disposed at one end of the main forming die 5 for forming the shaft portion 4 of the magnet roll 1, and disposed in the main forming die 5 so as to be able to move back and forth. In addition, with the injection of the molten resin magnet (hereinafter, referred to as a molten resin magnet) into the molding space 8 formed by the main mold 5, the resin magnet moves backward and moves to the end of the magnet roll 1, A slide mold 7 for forming the shaft 3 constitutes a mold for forming a magnet roll. In order to magnetize and orient the magnetic particles during the period from the start of injection of the molten resin magnet into the molding space 8 and the solidification of the molten resin magnet provided in the main molding die 5. And a magnetic field orientation means 9.

As shown in FIG. 4, the magnetic field orienting means 9 comprises four permanent magnets 10, 11, 12, 13 arranged at set intervals along the outer peripheral surface of the main mold 5. ing. The permanent magnets 10, 11, 12, 13
Are supported by a tip yoke 14 made of a soft magnetic material.
The rear ends of the first, second, and 13 are supported by a substantially cylindrical back yoke 15 made of a soft magnetic material. One of the permanent magnets 10, 11, 12, 13
Is larger than the other permanent magnets 10, 11, and 13, but the size relationship is not limited to this. Four magnetic poles are formed on the magnet roll 1 formed using the four permanent magnets 10, 11, 12, and 13. However, two, three, or five or more permanent magnets may be provided. Good. In addition to using a permanent magnet as the magnetic field orienting means 9, various existing structures such as an electromagnet can be adopted. The molten resin magnet is supplied from a not-shown injection cylinder or the like into the molding space 8 through the injection port 10 shown in the figure. The magnetic field orientation means 9
Is an electromagnet, as shown in FIG.
After the injection of the molten resin magnet is completely injected, the magnetization and orientation may be performed, and the start timing can be freely changed.

Further, between the adjacent permanent magnets 10 and 11 or 11 and 12 or 12 and 13 or 13 and 10
The cooling block 16 or 17 is made of a material having a higher thermal conductivity than the permanent magnet, for example, aluminum.
Or 18 or 19 is disposed in contact with the outer surface of the main mold 5. These cooling blocks 16, 1
Only specific ones of 7, 18, and 19 may be made of a material having high thermal conductivity. The cooling block 16 or 17
Or 18 or 19, cooling water passage 16A or 17A
Or, 18A or 19A is formed and the molten resin magnet injected into the main mold 5 is cooled by cooling blocks 16, 17, and
It is configured to be cooled by 18 and 19. FIG. 1 shows the cooling water passage 16A or 17A or 18A or 19A.
Put cooling water from one end and drain from the other end as shown in
In addition to the circulation system in which the discharged cooling water is returned to the cooling block side again through the cooling device, the cooling water supplied through the cooling device may be discharged to the outside without returning to the cooling device side. Further, it is desirable that the cooling water passages 16A, 17A, 18A, and 19A in the cooling block and the cooling block main bodies 16, 17, 18, and 19 be subjected to rust prevention treatment.

The cooling block 1 located between the large permanent magnet 12 and the adjacent permanent magnet 11 or 13
7 and 18 are smaller than the other cooling blocks 16 and 19, and the contact area between the cooling blocks 17 and 18 and the main mold 5 in contact with each other is reduced. In particular, the cooling block 17 has the smallest contact area. Therefore, the cooling capacity of the cooling block 17 or 18 is reduced.
Or, the cooling capacity of the molded product is lower than that of the cooling device of the embodiment 19, and the cooling of the compact is partially different. This tendency becomes more remarkable when the angle between the poles formed by the permanent magnets is small (not shown). Therefore, the cooling blocks 16, 17, 18, 1
9 is set to 100 ° C. or lower, and the surface temperature of the cooling block 17 or 18 having a small contact area with the main mold 5 is set to be 2 to 10 ° lower than the surface temperature of the other cooling block 16 or 19. By setting C lower, the cooling efficiency of the cooling block 17 or 18 is increased so that the molded body can be uniformly cooled. Specifically, as shown in FIG.
Temperature detection sensors 20, 21, 22, 23 for detecting the surface temperatures of 6, 17, 18, 19, and cooling block 1
Temperature setting means 24, 25, 26, 27 for setting the surface temperatures of 6, 17, 18, 19;
Cooling device driving means 28, 29, 30, 31 for driving a cooling device such as a heat exchanger for cooling the cooling water flowing in the inside of each of the temperature detection sensors 2, 17, 18, 19;
A drive signal or a drive stop signal is output to the cooling device drive means 28, 29, 30, 31 based on the detection information from 0, 21, 22, 23 and the setting information from the temperature setting means 24, 25, 26, 27. Temperature control means 32 for controlling the temperature of each of the cooling blocks 16, 17, 18, and 19 so as to match the set temperature. The location where the surface temperature of the cooling blocks 16, 17, 18, 19 is detected is optimally in contact with the main mold 5, but may be another surface or the cooling blocks 16, 1 may be used.
The internal temperatures of 7, 18, and 19 may be detected, and the surface temperature may be calculated from the internal temperatures. 6A shown in FIG.
Is an annular cooling water passage formed in the end portion forming die 6, which receives cooling water from above as shown by an arrow, flows out from below, and returns it to the cooling device side. In addition, the cooling water passage of the end molding die 6 may be omitted. Also, a cooling water passage is formed in the slide die 7 to control the surface temperature of the slide die 7. Although the cooling blocks 16, 17, 18, and 19 are cooled by cooling water flowing inside, the cooling air is directly blown by a cooling air generator that generates cold air, and the cooling blocks 16, 17, 1, 1 are cooled.
8 and 19 may be cooled.

The surface temperature of the cooling blocks 17 and 18 is set to be 2 ° lower than the surface temperature of the other cooling blocks 16 and 19.
C (Example 1), 5 ° C. (Example 2), 10 ° C. (Example 3) Reduced temperature, that is, the cooling block 1 on the high temperature side
The surface temperature of the cooling blocks 6, 18, and 19 was 70 ° C., and the surface temperature of the cooling block on the low temperature side, that is, the cooling block 17 having the smallest contact area with the main mold among the cooling blocks was 68 ° C. (Example 1). , 65 ° C (Example 2)
Also, the surface temperature of the cooling blocks 16 and 19 on the high temperature side is set to 70
° C, and the surface temperature of the cooling blocks 17 and 18 on the low temperature side is 60 ° C (Example 3). Each of the magnet rolls is formed, and the warpage direction, the amount of warpage, and the magnetic force variation in the longitudinal direction of the formed magnet rolls. (The difference between the maximum value and the minimum value of the magnetic force in the longitudinal direction) was measured. In addition, as a comparative example, all the cooling blocks 16, 17, 18, and 19 were set to the same surface temperature, and the above three items were measured.

[0018]

[Table 1]

As is clear from Table 1, cooling block 1
The warpage directions are almost the same when a temperature difference of 2 ° C. to 10 ° C. is applied than when the surface temperatures of 6, 17, 18, and 19 are all the same. Good results were obtained with both variations in magnetic force. FIG. 9 is a graph showing the amount of warpage with respect to the temperature difference for each surface temperature of the cooling blocks 16, 17, 18, and 19. From this graph, it can be seen that the cooling blocks 16, 17, 1
The surface temperatures of 8 and 19 in the range of 50 ° C. to 80 ° C. show good results with respect to warpage. Also, in FIG.
This is a graph showing the relationship between the amount of warpage and the variation in the zone magnetic force (the variation in the magnetic force in the longitudinal direction of the magnet roll). As the amount of the warpage increases, the variation in the zone magnetic force also increases. As a result of measuring the magnetic flux density of the magnet roll formed as described above, the magnetic flux density in the longitudinal direction was able to be made substantially uniform as shown in the graph of FIG. FIG. 12 shows a cooling block 16 as a comparative example.
This shows the case where the temperature control of 17, 18, and 19 was not performed (the same surface temperature was set), and it can be seen that the magnetic flux density fluctuated within the vertical range H in the longitudinal direction.

Next, a method of forming the magnet roll 1 will be described. As shown in FIG. 1, after driving the actuator 33 for moving the slide die 7 to move the slide die 7 to the forward position, the molten resin magnet is injected into the die through the injection port 34. Start the infusion. Examples of the actuator 33 include an air compressor, a hydraulic cylinder, a pneumatic cylinder, a screw screw,
A rack and pinion gear, a linear motor, or the like can be used. Next, as shown in FIG. 2, the molding space 8 is filled with the molten resin magnet while the slide die 7 is retracted to the retracted position by the combined force of the injection pressure of the molten resin magnet and the driving force of the actuator 33. . The actuator 3
When a hydraulic cylinder is used as 3, the working oil is leaked while being squeezed to apply a braking force to the backward movement of the slide die 7, so that the molten resin magnet is filled into the molding space 8 without gaps. It becomes possible. However, a braking force applying means for applying a braking force by friction or the like may be provided to apply the braking force when the slide die 7 moves backward. Further, the slide mold 7 may be retracted while applying a braking force by the actuator 33 in accordance with the injection injection speed of the molten resin magnet. Further, when the molten resin magnet is filled, the driving by the actuator 33 may be stopped. When the injection of the molten resin magnet is completed,
The magnetic particles are magnetized and oriented by the magnetic field orientation means 9 until the molten resin magnet is solidified.

After the injected and injected molten resin magnet is solidified, as shown in FIG. 3, the end mold 6 is moved away from the main mold 5 and then the slide mold 7 is advanced.
The magnet roll 1 is detached. The main mold 6 may be moved away from the end mold 7.

The cooling water passages 16A, 17A, 18A, 1
9A may be configured as shown in FIGS. That is, in FIG. 6, the hollow pipe 35 is disposed in a large groove formed from one end to the other end to form cooling water passages (17A and 19A in the figure), and the cooling water supplied through the hollow pipe 35 is provided. Water is applied to the outer surface of the hollow pipe 35 and the inner surface M of the groove.
And is discharged to the outside through a cooling water passage formed between them. In FIG. 7, two cooling water passages 17A, 17A are provided for one cooling block, for example, 17.
Is formed, and cooling is performed by increasing the volume of the cooling water passage. FIG. 8 shows a case where the supply port for supplying the cooling water and the discharge port for discharging to the outside are provided on the same side. The cooling water passage may have a flat inner surface, a projection may be provided on the inner surface to enhance the cooling effect, or a spiral shape.

In the above embodiment, the shaft portion and the roll portion are integrally formed. However, the present invention is also applicable to a shaft insert type magnet roll formed by inserting a metal or synthetic resin shaft. Can be adapted.

[0024]

According to the first aspect of the present invention, the magnet roll formed by the slide die is pushed out in the longitudinal direction and taken out to stabilize the magnetic force (zone magnetic force) in the longitudinal direction and reduce warpage. While the main mold is cooled by the cooling block, the dimensional change of each part of the mold due to thermal expansion can be kept low, and especially the clearance between the outer surface of the slide mold and the inner surface of the main mold is large. Since the change can be suppressed, generation of galling and generation of burrs can be prevented. Moreover, by providing a temperature difference between the cooling blocks, the cooling efficiency of the resin magnet composition cooled by the cooling block having a small contact area with the main mold can be increased. The magnet composition can be cooled uniformly over the entire area,
It is possible to further stabilize the magnetic force (zone magnetic force) in the longitudinal direction and further reduce warpage.

According to the second aspect, when the cooling temperature of the cooling block is set to 100 ° C. or less and the temperature difference is set to 2 to 10 ° C., both the amount of warpage and the variation in the longitudinal magnetic force are reduced. Good results can be obtained.

According to the third aspect, at least one or more of the cooling blocks is made of a non-magnetic material having a higher thermal conductivity than the member for forming the magnetic field orientation means, so that the cooling efficiency of the cooling block can be increased. For example, if a cooling block having a small contact area with the main mold is made of a non-magnetic material having a high thermal conductivity, a temperature difference can be minimized and energy can be saved. Moreover, by using a non-magnetic material having a high thermal conductivity only for a specific cooling block, the cost of manufacturing the cooling block can be minimized.

According to the fourth aspect, by using water that is easy to handle safely even if it touches the cooling medium,
Not only can the used water be discharged without purification, but also the water pipe is laid everywhere, so that the required amount of cooling medium can be easily obtained at any time.

[Brief description of the drawings]

FIG. 1 is a sectional view of a mold showing a state immediately before the start of injection of a molten resin magnet.

FIG. 2 is a cross-sectional view of a mold showing a state in which injection of a molten resin magnet is completed.

FIG. 3 is a sectional view of a mold showing a state where a formed magnet roll is detached.

FIG. 4 is a cross-sectional view when the mold is cut in a direction orthogonal to the longitudinal direction.

FIG. 5 is a block diagram showing surface temperature control of a cooling block.

FIG. 6 is a sectional view of a mold showing another embodiment of the cooling water passage.

FIG. 7 is a sectional view of a mold showing another embodiment of the cooling water passage.

FIG. 8 is a sectional view of a mold showing another embodiment of the cooling water passage.

FIG. 9 is a graph showing the relationship between the temperature difference and the amount of warpage.

FIG. 10 is a graph showing the relationship between the amount of warpage and the variation in zone magnetic force.

FIG. 11 is a graph showing a magnetic flux density distribution of the magnet roll of the present invention.

FIG. 12 is a graph showing a magnetic flux density distribution of a conventional magnet roll.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Magnet roll 2 Roll main body part 3, 4 shaft part 5 Main molding die 6 End molding die 6A Cooling channel 7 Slide die 8 Molding space 9 Magnetic field orienting means 10, 11, 12,
13 permanent magnet 14 tip yoke 15 back yoke 16, 17, 18, 19 cooling block (cooling block main body) 16A, 17A, 18A, 19A cooling water passage 20, 21, 22, 23 temperature detecting sensor 24, 25, 26, 27 temperature Setting means 28, 29, 30, 31 Cooling device driving means 32 Temperature control means 33 Actuator 34 Inlet 35 Hollow pipe M Inner surface

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification symbol FI // B29L 31:32

Claims (4)

[Claims] After applying a magnetic field of a plurality of poles to a resin magnet composition containing a magnetic powder and a binder as main components by a plurality of magnetic field orienting means, respectively, into a molding space formed by a mold. In the method for manufacturing a magnet roll that is removed from a mold, the mold includes, as the mold, one of a main molding die for forming a roll body of the magnet roll and one of shaft portions formed at both ends of the magnet roll. It comprises an end molding die disposed at one end of the main molding die to form a shaft, and a slide die slidably disposed within the main molding die to form the other shaft. A magnet roll is formed by using a mold, and after this molding, the slide die is protruded into the molding space so that the magnet roll is taken out of the die. The resin magnet composition injected and injected by a plurality of cooling blocks adjacent to the plurality of magnetic field orientation means arranged at predetermined intervals along the peripheral surface and in contact with the outer peripheral surface of the main mold. And a temperature difference between the cooling blocks. 2. A cooling temperature of the cooling block is set to 100 °.
C, and the temperature difference is set to 2 to 10 ° C., and the cooling temperature of the cooling block having a small contact area with the main mold is set lower than the cooling temperature of the cooling block having a large contact area. The method for manufacturing a magnet roll according to claim 1, wherein: 3. The method according to claim 1, wherein at least one of the cooling blocks is made of a non-magnetic material having a higher thermal conductivity than the magnetic-field-orienting member forming member. 4. The method according to claim 1, wherein the cooling block forms a flow path in which a cooling medium flows, and water is used as the cooling medium.