JP3165523B2 - Compacting mold for rotary transformer core and rotary transformer core - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a disk-shaped rotary transformer core having a plurality of concentric annular grooves for arranging coils, and a dust mold used for manufacturing the core.

[0002]

2. Description of the Related Art As shown in FIG. 3, a rotary transformer has a plurality of disk-shaped and concentric annular grooves 2 for disposing coils, each of which has a winding 3 facing each other, one of which is fixed, and the other is fixed. It rotates to form a transformer. Conventionally, a rotary transformer core used for this rotary transformer has been manufactured by press-molding ferrite powder with a compacting mold, sintering, and machining. FIG. 4 is a cross-sectional view illustrating a state around a mold of a powder compacting apparatus and a compact, showing a state at the time of conventional compacting, and showing a left half from a center line. The compacting body 9 of the rotary transformer core is formed by lowering the lower punch 6 and the flat upper punch 7 which are equally tapered to the inner and outer wall surfaces of the annular groove 11 for arranging the coil of the rotary transformer core with the die 5 and the center. The powder was compacted by moving up and down between 8 points. After the pressing is completed, the lower punch 6 is raised,
The green compact 9 is pushed up, and the lower surface of the green compact 9 is
The lower punch 6 descends and is released. When this green compact 9 is extruded onto the upper surface of the die 5, the green compact 9 is released from the pressure and expands.
For this reason, it is difficult to release the mold from the lower punch 6, and as shown in FIG.
There is a problem that cracks 10 are generated in the gap between the ridges and partial drop-off occurs. In particular, when the number of grooves is increased, this tendency is remarkable and there is a problem that the yield of products is reduced.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems and to provide a compacting die for a rotary transformer which does not cause cracks or partial dropping on a sintered rotary transformer core. Molded by mold,
An object of the present invention is to provide a rotary transformer core having a shape in which cracks and partial falling-off do not occur in a step after the powder compacting.

[0004]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention relates to a conventional rotary transformer core and a green compact molding die for a rotary transformer core, which are formed after pressing is completed and immediately before release. Expands and becomes difficult to be released from the lower punch, so that cracks are generated in the annular groove portion for arranging the coil of the green compact and the mountain width portion between the grooves, or a part of the compact is dropped. In order to improve the releasability of the body, the shape of the lower punch of the mold is designed so that the taper angles of the inner and outer walls of the annular groove for arranging the coils of the rotary transformer core are different from each other. Provided is a rotary transformer core and a compacting die for a rotary transformer core having a structure in which cracks and partial falling-off do not occur in powder molding and subsequent sintering and grinding processes.

That is, the present invention relates to a rotary transformer core compacting die for forming a disk-shaped rotary transformer core having a plurality of concentric annular grooves for coil arrangement, and further comprising a coil arrangement for the rotary transformer core. Angle of the taper of the mold part forming the center-side wall of each annular groove of the rotary transformer core,
And a compacting mold for a rotary transformer core, wherein the compacting mold for the rotary transformer core has a structure in which the angles of the extraction taper of the mold portions forming the outer wall of the annular groove are different from each other. In the mold, the angle of the taper of the mold forming the center wall of the annular groove of the rotary transformer core gradually increases from the center to the outside, and the mold forms the outer wall of the annular groove. A compacting die for a rotary transformer core, characterized in that the angle of the taper of the portion is gradually reduced from the center side to the outer side, and a concentric circle formed by the compacting mold described above. In a disk-shaped rotary transformer core having a plurality of annular coil-arranging grooves, a center-side wall of the annular groove of the coil-arranging annular groove portion of the rotary transformer core is provided. It is formed by a rotary transformer core characterized by a structure in which the angle of the extraction taper and the angle of the extraction taper of the outer wall of the annular groove are different from each other, and the compacting die for the rotary transformer core described above. In a disk-shaped rotary transformer core having a plurality of concentric annular grooves for disposing coils, the angle of the taper of the center-side wall of the annular groove of the rotary transformer core gradually increases from the center side to the outside. Get bigger,
A rotary transformer core characterized in that the angle of the taper of the wall outside the annular groove is gradually reduced from the center to the outside.

[0006]

A rotary transformer core having good releasability and free of cracks and the like is formed by using dies having different shapes of inner and outer wall surfaces of the annular groove portion for arranging the coil of the compacting die of the rotary transformer core. Since the green compact is manufactured, a reliable rotary transformer core with little variation in appearance quality and electric characteristics without cracks or falling off can be manufactured.

[0007]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a front cross-sectional view of the vicinity of a powder compacting mold used in the method of the present invention, showing a state after completion of pressurization. The rotary transformer core press-molds and sinters the granulated ferrite powder containing, for example, raw materials such as iron oxide, nickel oxide, copper oxide, and zinc oxide at a fixed mixing ratio, and sinters the same. Both sides are ground to obtain a rotary transformer core. Hereinafter, a description will be given using an example of compacting a rotary transformer core having four channels.
Like the rotary transformer core 1 shown in FIG. 2, the inclination of the wall 12 on the center side of the annular groove 2 is 9 degrees, 10 degrees from the center side.
Degrees, 11 degrees, and 13 degrees, gradually increasing outward. The inclination of the outer wall 13 of the annular groove 2 is gradually reduced toward the outside at 8, 6, 4, and 3 degrees from the center side. A powder compacting die for a rotary transformer core set to form this core was prepared. As shown in FIG. 1, the ferrite powder is filled in the die 5 using a compacting apparatus equipped with the compacting die, and then compacted by the lower punch 6 and then compacted by the lower punch 6. The body 9 is pushed out of the die 5. At that time, the green compact 9 is pushed upward along the taper of the outer wall 13 surface of the annular groove 2 portion of the lower punch 6 while expanding, and is released from the mold. Therefore, a good green compact without cracks or falling off was obtained. When a rotary transformer core having an outer diameter of 50 mm and the number of coil grooves of 4 channels was manufactured by the conventional method using the mold of the present embodiment, about 10% of falling off and cracks in the mountain width portion occurred. By using this mold, it was possible to manufacture a rotary transformer core having a good appearance without any falling off or cracking. Also, the electrical characteristics of the rotary transformer were maintained at the same level as before. Furthermore, as for the draft taper of the inner and outer walls of the groove, the appropriate draft taper size differs depending on the powder material,
The same effect was obtained as a result of performing an example having a large number of grooves with a tapered cutout adapted to various raw material powders.

[0008]

As described in the above embodiments, according to the present invention, a rotary transformer core capable of coping with multi-channels and not generating cracks or partial dropouts after powder compaction and before polishing is completed. A compacting die for a rotary transformer core that can be supplied by a rotary transformer core can be provided.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a state in which a rotary transformer core is formed using a powder molding die of the present invention, and shows a left half from a center line.

FIG. 2 is a sectional view showing an example of the rotary transformer core of the present invention, showing a right half from a center line.

FIG. 3 is a cross-sectional side view of a disk-shaped rotary transformer core in which wound coils are arranged.

FIG. 4 is a cross-sectional view showing a state in which a rotary transformer core is being formed using a conventional compacting mold, and shows a left half from a center line.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Rotary transformer core 2 (annular) groove 3 Winding 4 Center line 5 Die 6 Lower punch 7 Upper punch 8 Medium core 9 Green compact 10 Crack 11 (Circular) groove 12 Medium core side wall 13 Outside wall

Claims (4)

(57) [Claims] 1. A rotary transformer core compacting die for forming a disk-shaped rotary transformer core having a plurality of concentric annular grooves for disposing coils, wherein the annular groove portion for disposing the coils of the rotary transformer core is provided. In the mold to be molded, the angle of the extraction taper of the mold part forming the center wall of each annular groove of the rotary transformer core and the angle of the extraction taper of the mold part forming the outer wall of the annular groove are different. A powder compacting die for a rotary transformer core, which has a different structure. 2. The powder compacting die for a rotary transformer core according to claim 1, wherein an angle of a taper of a die portion forming a wall of the rotary groove on the center side of the annular groove is outside the center side. As you go,
A compacting mold for a rotary transformer core, wherein the angle of a taper of a mold portion forming an outer wall of an annular groove is gradually reduced from a center side to an outer side. 3. A disk-shaped rotary transformer core having a plurality of concentric annular grooves for disposing a coil formed by the powder compacting die according to claim 1, wherein the annular coil for disposing the coil of the rotary transformer core is provided. A rotary transformer core having a structure in which the angle of the taper of the center of the annular groove in the groove portion and the angle of the taper of the outer wall of the annular groove are different from each other. 4. A disk-shaped rotary transformer core having a plurality of concentric annular grooves for arranging coils formed by the powder compacting die for a rotary transformer core according to claim 2. It is configured such that the angle of the extraction taper of the wall on the center side of the groove gradually increases as going from the center side to the outside, and the angle of the extraction taper of the wall outside the annular groove gradually decreases as going from the center side to the outside. Rotary transformer core with a unique structure.