JP2886086B2 - Rotary transformer core intermediate product and method for manufacturing rotary transformer core using the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotary transformer core intermediate product and a method for manufacturing a rotary transformer core using the same.

[0002]

2. Description of the Related Art As shown in FIG. 5, a flat type rotary transformer, which is a kind of a rotary transformer used for a rotary magnetic head such as a VTR, has one side (principal plane) of a flat disk-shaped core 1 formed of ferrite. A plurality of concentric grooves 2
Is formed, and the winding 3 is mounted in the groove. A center hole 1a is formed at the center of the core 1. The back side of the core 1 is a flat surface. Two rotary transformers having such a configuration are prepared, and their main planes face each other as shown in FIG. 6, and are arranged rotatably with their axes aligned. That is, the lower rotary transformer 4a is fixed to the lower cylinder 5, and the upper rotary transformer 4b is lined up with the output shaft 6 of the motor.
It rotates with it. Thus, transmission and reception of electric signals are performed between the two systems.

By the way, in order to manufacture the core 1 having the above structure, as shown in FIG. 7, a ferrite powder is press-formed into a donut disk shape having a center hole 1a to manufacture a rotary transformer core intermediate product 7. The figure is drawn with the back surface (the side opposite to the main plane) facing upward.

Then, the ferrite powder is fired. At this time, as shown in FIG. 8, one intermediate product 7 is placed on a ceramic dish called a setter 8, and furthermore, A plurality of the setters 8 on which the intermediate products 7 are placed are installed on a large tray 9 and the entire tray 9 is passed through a heating furnace (a plurality of such trays 9 are also stacked) to be about 1000 to 1200 ° C. To heat and sinter.

[0005]

However, in the above-described conventional manufacturing method, since one intermediate product 7 is mounted on the setter 8, a wasteful space is generated on the intermediate product 7. Would. Further, when heating the intermediate product 7,
At the same time, the setter 8 and the tray 9 are also heated, and the heat capacity of the intermediate product 7 with respect to the total heat capacity required for heating (the heat capacity required to heat the intermediate product 7, the setter 8, and the tray 9) is reduced. Therefore, the heating efficiency is deteriorated.

Further, since there is a useless space above the intermediate product 7 disposed on the setter 8 as described above, the intermediate product cannot be efficiently disposed in the space in the heating furnace, and the firing process is performed at once. The number of intermediate products 7 that can be produced is small, and the working efficiency is deteriorated.

On the other hand, in order to solve the above problem, it is conceivable to place a plurality of intermediate products 7 on the setter 8, but in this case, except for the intermediate product arranged at the uppermost end, it is exposed to the outside. The surface is small (approximately the side peripheral surface), and firing failure occurs due to insufficient heat. In addition, although outgassing occurs in the intermediate product 7 due to firing, outgassing is poor if the exposed surface is small,
Phenomena such as a different shrinkage ratio at each part occur, and cracks, warpage, and the like occur accordingly. Therefore, a defective product is manufactured, and the yield is reduced.

The present invention has been made in view of the above-mentioned background, and has as its object to solve the above-mentioned problems, to allow a plurality of core intermediate products to be laminated, and to be fired at once. Increasing the number of cores to improve manufacturing efficiency, and enabling cores (intermediate products) to be placed in previously wasted spaces, effectively using heating energy for core firing Rotary transformer core product with high yield and rotary transformer using the same, which can minimize the occurrence of defective products such as firing failure and cracks due to insufficient heat capacity An object of the present invention is to provide a method for manufacturing a core.

[0009]

In order to achieve the above object, a rotary transformer core intermediate product according to the present invention comprises:
Finally, a number of small projections were integrally formed on the back surface of the disk-shaped core body opposite to the main plane on which the winding was mounted.

In the method for manufacturing a rotary transformer core according to the present invention, a plurality of intermediate products of the rotary transformer core having the above-described configuration are prepared, and are stacked so as to face in the same direction. Next, after heating and baking in that state, at least the rear side was polished to remove the small projections.

[0011]

When a plurality of intermediate products of the rotary transformer are stacked so as to face in the same direction, the intermediate products vertically adjacent to each other are formed by a small projection in which the main plane of one intermediate product is formed on the back surface of the other intermediate product. Contact with. By this, between both sides,
A gap (space) corresponding to the height of the small protrusion is formed. When heating and baking in this state, heat is smoothly transmitted between the opposing surfaces of the stacked intermediate products via the gaps, so that each intermediate product is sufficiently and uniformly heated. In addition, a gas is generated from the inside of the intermediate product by heating, and the gas also escapes to the outside through the gap. Therefore, no crack or the like is generated.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of a rotary transformer core intermediate product according to the present invention and a method for manufacturing a rotary transformer core using the same will be described in detail with reference to the accompanying drawings. FIG.
Shows an embodiment of a rotary transformer core intermediate product according to the present invention. As shown in the figure, a donut disk-shaped core body 11 having a central hole 10 is formed of a magnetic material such as ferrite. And this core body 1
A cutout groove portion 12 that extends in the radial direction and has one end reaching the periphery of the core body 11 is formed on the main surface side 11a (the surface on which the groove for mounting the winding in the final product) is formed. .
In this state, no concentric grooves into which the coils are inserted and arranged are not formed. And the notch groove 12
Are arranged so as to cross the concentric grooves to be finally formed, and serve as a passage for drawing out the coil inserted into the grooves to the outside.

In the present invention, a number of small projections 13 are formed on the back surface 11b opposite to the main plane 11a. The small projections 13 have the same hemisphere,
If the shapes are different, it is preferable that at least the heights of the small projections 13 are all the same. Thereby, the upper end (apex) of each small projection 13 is located on the same plane. Furthermore, the rotary core intermediate product 15 formed in such a shape has relatively low strength before firing, and
As will be described later, the gap / space formed between the small protrusions 13 only needs to be a gas vent passage at the time of burning, so that the protrusion amount (height) is set small (for example, about 0.5 to 2 mm). ing. In order to manufacture the rotary core intermediate product 15 having such a shape, a ferrite powder is filled in a mold having a predetermined shape (a concave portion corresponding to a small protrusion is further formed in the shape of a conventional mold). It can be formed by press molding.

In the above-described embodiment, the small projection 13 formed on the back surface 11b is hemispherical. However, the shape is arbitrary. Good. However, in consideration of the contact resistance between the other rotary transformer core and the main plane, it is better to have a spherical tip as in this embodiment than to a sharp tip,
If the heights of the small projections vary, it is better to make the tip curved as in this embodiment, rather than rectangular or grain.

Next, an embodiment of a method for manufacturing a rotary transformer core according to the present invention will be described using the rotary transformer core intermediate product 15 described above. As shown in FIG. 2, a plurality (three in this example) of rotary transformer core intermediate products 15 having the above-described configuration are stacked and arranged on the setter 16. At this time, all the three rotary transformer core intermediate products 15 are oriented in the same direction (the back surface 11b is upward in the illustrated example).

Then, as shown in the figure, the rotary transformer core intermediate products 15 located at the uppermost and middle positions respectively correspond to the rotary transformer core intermediate products 1 located thereunder.
5 are supported by a large number of small projections 13. That is, the apex of the small protrusion 13 of the lower rotary transformer core intermediate product 15 and the upper rotary transformer core intermediate product 15
Contact with the main plane 11a. As a result, a gap 17 is formed between the main plane 11a and the back surface 11b of the vertically adjacent rotary transformer core intermediate product 15 by the height of the small protrusion 13. In this state, a plurality of trays are placed in a large tray (see FIG. 8) as in the prior art, and the trays are inserted into a heating furnace (1000-1200 ° C. atmosphere) in a stacked state.

Thus, each rotary transformer core intermediate product 15 stacked together with the setter 16 and the tray is heated and fired. At this time, in this example, the main plane 11a and the back surface 11b of each of the intermediate products of the rotary transformer core laminated through the gap 17 are exposed, so that they are exposed to the high temperature atmosphere in the heating furnace, and the heat circulation is good and uniform. Heated.
Further, the gas in the rotary transformer core intermediate product 15 tends to escape to the outside by firing, but since the gap 17 serves as a gas escape passage, the gas escape is performed smoothly.
Therefore, the gas is uniformly vented as a whole, and the gas is not uniformly shrunk to cause warpage or cracks, so that the yield is improved.

Since three rotary transformer core intermediate products 15 are mounted on one setter 16, the number of rotary transformer core intermediate products that can be fired at one time is three.
And production efficiency is improved. Further, as the number of the rotary transformer core intermediate products 15 increases, the ratio of the heat capacity of the rotary transformer core intermediate product 15 to the heat capacity required to heat the setter 16, the tray and the entire rotary transformer core intermediate product 15 also increases. Also, the thermal efficiency is improved.

After firing as described above, the entire tray is taken out of the heating furnace (actually, since the tray moves in the heating furnace at a constant speed, it is heated and fired while moving, and automatically after the firing process is completed). As shown in FIG. 3, the rotary transformer core intermediate product 15 baked is placed on a magnet table 20 as shown in FIG. 3. At this time, the main plane 11a is set downward. Then, since the rotary transformer core intermediate product 15 is a magnetic material made of ferrite, the rotary transformer core intermediate product 15 is attracted and held on the magnet table 20 by magnetic force.

In this state, the back surface 11b side of the rotary transformer core intermediate product 15 is cut and polished using the polishing grindstone 21. Thereby, the small protrusion 13 is cut off. Further, after the small projections 13 are completely removed, polishing is performed for a predetermined distance (polishing to a position indicated by a broken line in the drawing), and adjustment is performed so that the thickness is as specified. Then, the main plane 11a
On the side, a plurality of concentric grooves for inserting coils are formed. Thereby, a rotary transformer core is manufactured.

The polishing step is a process performed to adjust the thickness of the rotary transformer core to a specified value. That is, according to the present embodiment, the conventional manufacturing process can be used as it is, except that the rotary transformer core intermediate product having the predetermined shape is used and a plurality of the rotary transformer cores are stacked on the setter. That is, the present invention can be carried out without changing the manufacturing equipment used conventionally. Then, the number of rotary transformer cores that can be manufactured at one time can be increased, and the productivity is improved.

In the above-described embodiment, the number of intermediate products of the rotary transformer core to be laminated is three, but the number of laminated products is arbitrary. Further, in the above-described embodiment, the rotary transformer core intermediate product is laminated with the back surface facing upward.
When laminating the rotary transformer core intermediate product 15 as shown in FIG.

[0023]

As described above, in the rotary transformer core intermediate product according to the present invention, since the small projections are provided on the back side, when such intermediate products are stacked so as to face in the same direction, the small projections cause A gap is created between the opposing surfaces of the intermediate products adjacent to. The gap can be used as a passage for heat transfer during heating and as a passage for venting gas. Therefore, even if the sintering process is performed with the layers stacked, the occurrence of defective products such as cracks and warpage can be suppressed as much as possible.

Therefore, in the method for manufacturing a rotary transformer core according to the present invention, since the baking process can be performed in a laminated state using the rotary transformer core intermediate product of the present invention, the number of intermediate products that can be processed at a time, that is, the number of rotary transformer cores increases. The manufacturing efficiency is improved. In addition, since the layers can be stacked and arranged in this manner, the core (intermediate product) can be arranged in a part (space above the intermediate product) which was conventionally wasted space. Therefore, the heating energy can be effectively used for firing the core to improve the heating efficiency, and the occurrence of defective products such as defective firing and cracks due to insufficient heat capacity can be suppressed as much as possible. , And the yield is improved. Since the small protrusions formed on the back side are removed after firing, there is no problem in the product characteristics, and the removal processing can use the conventional polishing processing of the back surface after firing as it is. Also, there is no increase in the number of manufacturing steps.

[Brief description of the drawings]

FIG. 1 is a view showing a preferred embodiment of an intermediate product of a rotary transformer core according to the present invention.

FIG. 2 is a view showing one step in a preferred embodiment of the method for manufacturing a rotary transformer core according to the present invention.

FIG. 3 is a view showing another step in a preferred embodiment of the method for manufacturing a rotary transformer core according to the present invention.

FIG. 4 is a diagram showing another embodiment.

FIG. 5 is a diagram illustrating an example of a rotary transformer core.

FIG. 6 is a diagram showing an example of a conventional method for manufacturing a rotary transformer core.

FIG. 7 is a diagram showing an example of a conventional method for manufacturing a rotary transformer core.

FIG. 8 is a diagram showing an example of a conventional method for manufacturing a rotary transformer core.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Rotary core main body 11a Main plane 11b Back 13 Small protrusion 15 Intermediate product 21 Grinding stone

Claims (2)

(57) [Claims] 1. An intermediate product before firing of a flat disk-shaped rotary transformer core having a main plane having a groove in which a winding is finally mounted, and a back surface opposite to the main plane, Rotary transformer core intermediate product formed by integrally molding many small protrusions. 2. A plurality of intermediate products of the rotary transformer core according to claim 1, which are stacked so as to face in the same direction, heated and fired in that state, and at least the back side is polished. A method for manufacturing a rotary transformer core in which the small protrusion is removed.