JP3327261B2 - Manufacturing method of rotary transformer - Google Patents

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 rotary transformer used in a rotary magnetic head device such as a video tape recorder and a digital audio tape recorder.

[0002]

2. Description of the Related Art A rotary transformer is a connection means for transmitting a signal obtained by a rotary magnetic head provided on a rotary side to a fixed side circuit in a rotary magnetic head device such as a video tape recorder or a digital audio tape recorder. Widely used as.

Conventionally, as a rotary transformer of this type, for example, as shown in FIG. 6, a pair of cylindrical magnetic cores 51 and 52 having different outer diameters are coaxially arranged to face inward and outward. A vertical rotary transformer is known.

This rotary transformer comprises a magnetic core 51 attached to the fixed side, ie, a stator, and a magnetic core 52 attached to the rotating side, ie, a rotor, and is provided on opposing surfaces of these magnetic cores 51, 52, respectively. Annular coils 55 and 56 are arranged in the concentric winding grooves 53 and 54 thus formed. Then, the rotary transformer includes the magnetic cores 51 and 52.
For example, by the electromagnetic coupling between the coils 55 and 56, for example, a rotary magnetic head connected to one magnetic core 51 and a reproducing circuit connected to the other magnetic core 52 are connected,
Transmits video signals, digital audio signals, etc.

By the way, in order to manufacture a rotary transformer, magnetic powder such as ferrite is pressed using a mold or formed into a cylindrical core by injection molding. The grooves 53 and 54 and the lead grooves (not shown) for leading the terminals of the coils 55 and 56 are formed by grinding.

After the firing, the winding grooves 53 and 54 and the extraction grooves are ground because the core is distorted or deformed due to a difference in heat conduction during the firing. These winding grooves 5
3, 54 and the lead groove are integrally molded by injection molding,
When firing is performed thereafter, the winding grooves 53, 5 are fired.
4 and the size of the lead groove fluctuate remarkably, making it impossible to secure a specified size. Therefore, the winding grooves 53 and 54 and the lead groove have to be formed by grinding after firing. Further, since the winding grooves 53 and 54 and the lead-out groove have a large deformation amount due to firing and a considerable amount of grinding is required, it is preferable to process after firing.

In the rotary transformer, the terminals of the coils 55, 56 led out of the winding grooves 53, 54 through the lead grooves are connected to the device side by molding resin on one side surface of the magnetic cores 51, 52 with resin. Molded portions 57 and 58 are provided, and terminals of the coils 55 and 56 are wound around terminals 59 and 60 attached to the molded portions 57 and 58 for connection.

A rotary transformer using a molding technique is disclosed in, for example, JP-A-62-1285.
As disclosed in JP-A-07-07, there has been proposed a rotary transformer in which an annular coil is molded and the molded body is fitted and disposed in a winding groove.

However, it is necessary to manufacture the mold portions 57 and 58 in a step different from the step of manufacturing the magnetic cores 51 and 52. For this reason, the number of manufacturing steps increases, and the productivity deteriorates.
In addition, the molding portions 57 and 58 are formed with the magnetic cores 51 and 52.
Since it is necessary to perform an operation of attaching the device to the device, the operation is also required. On the other hand, the rotary transformer disclosed in the above-mentioned publication also has a disadvantage in improving productivity because the molded body is a separate member.

[0010]

As described above, since the above-mentioned rotary transformer requires firing,
It is necessary to perform the groove processing of the winding groove and the lead groove after firing, and not only there are many troublesome operations, but also many manufacturing processes,
The productivity cannot be improved.

Further, in the above-mentioned rotary transformer, since a mold body is manufactured in a separate step separately from the magnetic core, a step for manufacturing the mold body is required, and improvement in productivity cannot be expected.

The present invention has been proposed in view of such conventional circumstances, and an object of the present invention is to provide a method of manufacturing a rotary transformer capable of manufacturing a highly accurate rotary transformer with high productivity.

[0013]

In order to achieve the above-mentioned object, the present invention provides, on one surface, a concentric winding groove,
A lead-out groove for leading out a terminal of the coil provided in the winding groove is provided, and a through hole for leading out the terminal of the coil is provided in the collar portion, and a wiring is provided on the back side of the terminal of the coil on the device side. In the method for manufacturing a rotary transformer having a magnetic core provided with a terminal for connecting the magnetic core, a material obtained by kneading a spinel-formed magnetic powder and a polymer material is used, and the terminal is connected to the collar portion. It is arranged in a mold used for injection molding in advance so as to be provided at a predetermined position, and thereafter, the winding groove, the drawing groove, the collar portion, the through hole, and the terminal are simultaneously injection-molded integrally. It was done.

In the present invention, a winding groove and a terminal of a coil provided in the winding groove are formed on a molded body obtained by injection molding a material obtained by kneading a magnetic powder kneaded with a polymer material by firing and spinning. Since the lead-out groove to be led out is integrally formed, it is used as it is as a magnetic core without firing.

The magnetic powder constituting the magnetic core includes, for example, Mn-Zn ferrite which has been baked and turned into a spinel,
Metal oxide powders such as i-Zn ferrite and Ni-Cu-Zn, metal powders such as iron and nickel, and metal alloy powders such as carbonyl iron and sendust can be used, and these may be used alone. , May be used as a mixture of two or more. Among them, metal oxide powders of Mn-Zn ferrite and Ni-Zn ferrite are particularly preferable.

On the other hand, a thermoplastic resin is preferable as the polymer material. Such thermoplastic resins include, for example, polypropylene, polyethylene, polyamide, polycarbonate, polybutadiene terephthalate, polyphenylene sulfide, polystyrene, acrylonitrile butadiene styrene resin, acrylonitrile styrene resin, polyethylene terephthalate, polymethyl methacrylate, polyacetal, polytetrafluoroethylene ,
Polyvinyl acetate, polyvinyl butyral, vinyl chloride vinyl acetate copolymer, polychlorotrifluoroethylene,
Diallyl phthalate resin, polyisobutylene, polyurethane, polyvinyl alcohol, polyvinyl chloride, polyvinylidene chloride, polyvinyl fluoride, styrene butadiene,
Thermotropic type liquid crystal resin and the like can be mentioned.

Further, it is preferable to mix a lubricant and a plasticizer with the kneaded product comprising these materials in order to improve the fluidity during molding.

Examples of the lubricant include cadmium stearate, cadmium laurate, cadmium ricinoleate, cadmium naphthenate, cadmium 2-ethylhexoate, barium stearate, barium laurate, barium ricinoleate, barium naphthenate,
Barium ethylhexoate, calcium stearate, calcium laurate, calcium ricinoleate,
Metal soaps such as zinc stearate, zinc laurate, zinc ricinoleate, zinc 2-ethylhexoate, lead stearate, dibasic lead stearate, lead naphthenate, tin stearate, and magnesium stearate are included. Among them, barium stearate, calcium stearate, zinc stearate, lead stearate, and magnesium stearate are more preferable.

Examples of the plasticizer include phthalic acid-based lubricants such as dibutyl phthalate, dioctyl phthalate, diisodecyl phthalate, butyl lauryl phthalate, ditridecyl phthalate and butyl benzyl phthalate; and tricresyl phosphate and trioctyl phosphate. Phosphoric acid lubricants and the like can be mentioned.

A coupling agent may be used for the purpose of improving the adhesion between the magnetic powder and the thermoplastic resin.
Suitable coupling agents include, for example, titanate-based coupling agents, silane-based coupling agents, and the like.

In the magnetic core obtained by injection molding, since the magnetic powder is uniformly pressed in all directions in the mold, the generation of residual stress is small, and the distribution of the packing density becomes uniform, and the magnetic core is cracked. Is suppressed. Injection molding is a molding method that enables the production of very fine shapes, and is therefore suitable for molding a core having a complicated shape.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A method for manufacturing a rotary transformer according to the present invention will be described below with reference to the drawings.

The example shown here is an example in which the method of the present invention is applied to a vertical rotary transformer in which cylindrical magnetic cores having different outer diameters are arranged coaxially and in close proximity to each other inside and outside. In the present embodiment, a description will be given by taking a magnetic core disposed inside of these magnetic cores as an example.

The magnetic core 1 is, for example, a stator attached to the fixed side of the drum, and is formed by injection molding a material obtained by kneading spinel-formed magnetic powder and a polymer material. As shown in FIGS. 1 and 2, a coil 2 is formed on the outer peripheral surface 1a of the cylindrical member.
, A short ring groove 4 for disposing a short ring 6, and a lead groove 5 for leading out the terminals 2a and 2b of the coil 2 are integrally formed and provided.

The winding groove 3 is for disposing a coil 2 made of, for example, an annular shape or a coil made of a simple wire. The winding groove 3 has a substantially U-shaped cross section on the outer peripheral surface 1 a of the magnetic core 1. It is formed in an annular shape. The winding groove 3 is
The same number of channels as required at predetermined intervals along the axial direction of the magnetic core 1 are provided.

On the other hand, the short ring groove 4 is provided with a short ring 6 made of an insulating wire or the like for preventing mutual interference between the coils 2 provided in the winding groove 3, generation of noise, change in inductance, and the like. And provided between the winding grooves 3. The short ring groove 4 is also formed in an annular shape as a groove having a substantially U-shaped cross section, similarly to the winding groove 3.

The lead-out grooves 5 are for leading out the terminals 2a, 2b of the coils 2 arranged in the respective winding grooves 3 to the drum side, and a part of each of the winding grooves 3 to the drum of the magnetic core 1. Is provided along the axial direction to the one end edge side which is the mounting side of the. That is, the lead groove 5 is formed as a vertical groove deeper than a part of each winding groove 3 and deeper than the bottom of the winding groove 3 to a portion reaching one edge side along the axial direction of the magnetic core 1. In addition, the lead groove 5 is formed up to a portion which reaches a flange portion 7 described later provided at one axial end portion of the cylindrical magnetic core 1.

To ensure that the magnetic core 1 is attached to the drum, an annular flange formed at one edge in the axial direction so as to protrude outward from the cylindrical outer peripheral surface 1a. A part 7 is provided. The flange 2 has a terminal 2 of the coil 2 guided out of the lead-out groove 5.
Terminals 8a and 8b for connecting a and 2b to wiring provided on the device side are provided. These terminals 8a, 8
b is provided in the vicinity of the outer peripheral edge of the brim portion 7 so as to be erected in the thickness direction, and the tip of the b protrudes from the attachment surface 7a to the drum.

The collar 7 has terminals 2a, 2b of the coil 1
Through holes 9a and 9b are provided at positions close to the terminals 8a and 8b. Therefore, the terminals 2a and 2b of the coil 1 are led out through the respective through holes 9a and 9b toward the mounting surface 7a on the drum, and are connected to the terminals 8a and 8b on the mounting surface 7a on the drum. Note that these coils 1
The terminals 2a, 2b and the terminals 8a, 8b are connected by soldering or the like.

The collar 7 is provided with a mounting hole 10 for fixing a bolt for simplifying the operation of mounting the magnetic core 1 on the drum and improving reliability. This attachment hole 10 is also formed so as to penetrate in the thickness direction of the collar portion 7 like the through holes 9a and 9b.

Incidentally, the magnetic core 1 constructed as described above is manufactured as follows.

First, an injection molding material in which ferrite or the like that has been baked and turned into a spinel is kneaded in a binder is injected into a mold to perform injection molding.

At this time, the winding groove 3, the short ring groove 4, the drawing groove 5, the flange 7, the through holes 9a and 9b, and the mounting hole 10 are integrally formed at the same time. Also, terminals 8a, 8
b is previously arranged in the mold so as to be provided at a predetermined position of the collar portion 7 during molding.

[0034] Injection molding is a technique capable of producing very fine and complicated shapes, so that the above-mentioned complicated shapes can be easily formed. In particular, injection molding is effective for forming a vertical groove like the drawing groove 5 in the magnetic core 1 having the flange-shaped flange portion 7 as in this example. Therefore, simplification of the manufacturing process such as groove processing and hole processing can be expected, and the productivity can be greatly improved.

Next, the coil 2 is disposed in the winding groove 3 without firing the magnetic core 1 after the injection molding, and the short ring 6 is disposed in the short ring groove 4.

Then, the terminals 2a and 2b of the coil 2 are guided along the lead-out groove 5, and the ends thereof are inserted into the through holes 9a and 9b provided in the collar portion 7, and the mounting surface of the collar portion 7 to the drum is provided. It is guided to the side 7a and wound around the terminals 8a and 8b for soldering.

Next, after finishing the winding process and the lead process, the outer diameter R and the height H of the magnetic core 1 are ground to predetermined values.

As a result, the outer peripheral surface 1a of the magnetic core 1 and both ends in the height direction are ground to have a predetermined outer diameter and a predetermined height. At this time, the coil 2 itself disposed in the winding groove 3 is also ground along with the grinding of the outer peripheral surface 1a of the magnetic core 1, and as shown in FIG. 3, the outer peripheral surface 1a of the magnetic core 1 and the coil 2 are disposed. The coil portion provided, that is, the ground surface of the coil 2 is substantially flush. Therefore, the facing distance between the magnetic core 1 and the other magnetic core 11 arranged to be opposed is reduced, and the characteristics as a rotary transformer are improved.

In this embodiment, since the magnetic core 1 is not fired after injection molding, the amount of distortion and deformation generated in the magnetic core 1 is small, and the magnetic core 1 can be accurately ground with a small amount of grinding. Accordingly, the outer diameter R and the height H of the magnetic core 1 can be made highly accurate, and the grinding operation time can be greatly reduced.

The other magnetic core 11, which is disposed to face the outside, is manufactured by injection-molding the winding groove, the short ring groove, the lead groove and the like at the same time, similarly to the above-described magnetic core 1. Of course, the magnetic core 11 is provided with a winding groove and a short ring groove at positions facing the winding groove 3 and the short ring groove 4 provided on the one magnetic core 1 on the inner peripheral surface.

The magnetic cores 1, 11 manufactured as described above
As shown in FIG. 4, the magnetic core 1 provided on the inner side is mounted, for example, on the lower drum 12 on the fixed side while being regulated, and the magnetic core 11 disposed on the outer side is regulated on the upper drum 13 on the rotating side. Be attached.

Lower drum 1 of magnetic core 1 arranged inside
As shown in FIG. 5, the attachment to the second drum 2 is fixed by fastening a bolt 14 inserted into an attachment hole 10 provided in the flange 7 to a screw 15 provided in the lower drum 12.
For this reason, the work of attaching the magnetic core 1 to the lower drum 12 can be easily performed, and the attachment state is stabilized. On the other hand, the magnetic core 1 disposed on the outer side
Attachment is made by fastening a bolt inserted into an attachment hole provided in the collar portion to a screw portion provided in the collar portion.

As a result, the magnetic cores 1 and 11 are opposed to each other on the rotating side and the fixed side with a small gap therebetween, and the magnetic cores 1 attached to the upper drum 13 on the rotating side are arranged.
Video signals, digital audio signals, and the like are transmitted by electromagnetic coupling between the coils 1 and the magnetic core 1 attached to the fixed side.

In the rotary transformer constructed as described above, the outer diameter and height of the magnetic cores 1 and 11 are accurately determined and are mounted on the drums 12 and 13 with high accuracy. , 11 are extremely small, and an improvement in characteristics can be expected.

In the above description, the present invention has been described with reference to an example in which the present invention is applied to a vertical rotary transformer in which cylindrical magnetic cores having different outer diameters are arranged close to each other inside and outside. The present invention can also be applied to a flat type rotary transformer in which a plate-shaped magnetic core is opposed to each other with a small gap.

[0046]

As described above, the present invention uses a material obtained by kneading a spinel-formed magnetic powder with a polymer material, and injects a terminal for connecting the terminal of the coil to the wiring provided on the apparatus side in advance by injection molding. Placed in the mold used for
Since the winding groove, the lead groove, the collar, the through hole, and the terminal are simultaneously and integrally injection-molded, it is not necessary to perform difficult groove processing or the like. Since subsequent baking and processing for providing grooves and holes are not required, manufacturing is further facilitated.

Further, since the magnetic core having the winding groove, the lead groove, the brim portion, the through hole, and the like is integrally formed by injection molding, it is possible to expect an improvement in dimensional accuracy. The distance can be shortened, and the characteristics as a rotary transformer can be improved.

[Brief description of the drawings]

FIG. 1 is an enlarged sectional view showing one magnetic core (stator) constituting a rotary transformer to which the present invention is applied.

FIG. 2 is a plan view of the magnetic core.

FIG. 3 is an enlarged sectional view showing a winding groove provided in a magnetic core.

FIG. 4 is a cross-sectional view showing a state where the rotary transformer is mounted on a drum.

FIG. 5 is an enlarged sectional view of a main part showing a state in which a magnetic core (stator) is attached to a lower drum.

FIG. 6 is an enlarged sectional view showing an example of a conventional rotary transformer.

[Explanation of symbols]

Reference Signs List 1 magnetic core, 2 coil, 2a, 2b end of coil, 3 winding groove, 4 short ring groove, 5 drawing groove, 7 flange, 12 lower drum, 13
Upper drum.

Claims (1)

(57) [Claims] 1. A concentric winding groove and a lead groove for leading a terminal of a coil disposed in the winding groove are provided on one surface, and a lead portion for leading a terminal of the coil is provided in a flange portion. Piercing
The terminal of the above coil is provided on the device side with the through hole and the back side.
Magnetic core with terminals for connecting to
In the method for manufacturing a rotary transformer, the magnetic core comprises a spineled magnetic powder and a polymer material.
And the above-mentioned terminal is the above-mentioned collar part.
A mold used for injection molding in advance so as to be provided at a predetermined position
Arranged in the winding groove, the drawing groove, the collar,
Injection molding the through hole and the terminal at the same time
A method for producing a rotary transformer.