JPH0665204B2 - Method of manufacturing rotary transformer core - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention transmits a signal detected by a rotation sensor in various control devices or detection devices, a rotary head of a video tape recorder, or the like to a stationary circuit portion, or On the contrary, the present invention relates to a core of a rotary transformer which is widely used as a means for transmitting a control or recording signal to a rotating portion.

(Prior Art) A core of a general rotary transformer is obtained by press-molding ferrite powder and firing it. Then, the annular groove for winding is formed by a mold during pressure molding. This conventional rotary transformer core shrinks during firing,
At this time, uniform shrinkage was difficult and the core was deformed. Therefore, as described in JP-A-54-9717, there is a method of forming an annular groove by grinding.

(Problems to be Solved by the Invention) As described above, in the method of obtaining each annular groove by grinding, each annular groove can be formed with high dimensional accuracy. However, dimensional variation of the inner diameter of the core occurs, workability when assembling the core into the cylinder is poor, or dimensional variation of the outer diameter of the core occurs, and the outermost annular groove and the outer diameter There was a problem that characteristic variations occurred due to dimensional variations between the two. Further, the dimensional variation between the innermost annular groove and the inner diameter due to the dimensional variation of the inner diameter, and the characteristic variation due to the dimensional variation were also the same.

As a countermeasure against this, the present inventor has previously filed that the grinding of the inner diameter of the core is performed at the same time as the grinding of the annular groove (Japanese Patent Application No. 59-197380). This method improves the dimensional accuracy of the inner diameter. be able to. However, the dimensional variation of the outer diameter was the same as before.

Here, it was impossible to grind the outer diameter of the core simultaneously with the grinding of the annular groove and the inner diameter, because the core was chucked at the outer peripheral portion.

Also, contrary to the above, it is possible to grind the outer diameter of the core and the annular groove at the same time, but it is also possible to grind the inner diameter at the same time, as is the case with the above. It was impossible because of King.

Of course, if the grinding process is performed twice, the above is possible, but it takes a lot of man-hours.

In view of the above, the present invention easily provides a rotary transformer core with good dimensional accuracy.

(Means for Solving the Problems) In the present invention, the inner diameter and the annular groove of the core are ground, and at the same time, a step is formed on the outer circumference of the core, or
The outer diameter and the annular groove of the core are ground, and at the same time, the step of forming a step on the inner circumference of the core is performed.

(Operation) The present invention is to grind either one of the inner diameter or the outer diameter of the core and the grind processing of the annular groove of the core, and at the same time, perform the grinding process on the other outer peripheral portion or inner portion of the inner diameter or the outer diameter. Although it is to simultaneously perform a grinding process to form a step in the peripheral portion, in the outer peripheral portion or the inner peripheral portion forming the step, the grindstone to be ground does not reach the back surface of the ground surface of the core, Since it stops midway, the core is chucked between the position where the grindstone stops and the back surface.

Therefore, it is possible to perform grinding with a single grinding process between the annular grooves on the inner surface of the rotary transformer core, between the outermost annular groove and the outer circumference, and between the innermost annular groove and the inner circumference with extremely high dimensional accuracy. Further, as a rotary transformer, the positions of the opposing annular grooves can be made accurate, and high performance can be achieved.

(Embodiment) FIG. 1 is a sectional view of an embodiment according to the present invention.
The drawings are cross-sectional views showing a manufacturing method according to an embodiment of the present invention. In this embodiment, a disc-shaped ferrite core 1 and a grindstone 2 are used.
Is used to form the concentric circular groove 3, the inner diameter 4, and the step 5 on the outer peripheral portion by grinding. At the time of processing, the core 1 is fixed by the chuck jig 6. Therefore,
In this embodiment, each annular groove 3 and the outermost annular groove 3a and the outer circumference 7 are
And between the innermost annular groove 3b and the inner diameter 4 are formed with high precision.

FIG. 3 is a sectional view of another embodiment according to the present invention. In this embodiment, a grindstone is used for the disk-shaped core 8 and the annular groove 9, the outer diameter 10 and the step 11 on the inner circumference are formed by grinding. Also in this embodiment, the dimensions between each annular groove 9 and the outermost annular groove 9a and the outer diameter 10 and between the innermost annular groove 9b and the inner circumference 12 are formed with high precision. At the time of this processing, the core is chucked on the back surface side of the ground surface of the inner peripheral portion.

(Effects of the Invention) The present invention forms the annular groove and the outer diameter and the inner diameter of the facing surfaces of the rotary transformer core with high accuracy, and the characteristic variation between the rotary transformer cores can be made extremely small. Also, even when incorporated as a rotary transformer, the opposing channel corresponds to high precision,
To achieve high performance of the rotary transformer,
Further, since the annular groove and the outer diameter and the inner diameter are machined by one-time grinding, it is possible to form the highly accurate rotary transformer core as described above without spending man-hours, which is extremely useful in industry. is there.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of one embodiment according to the present invention.
FIG. 3 is a sectional view showing a manufacturing method of an embodiment according to the present invention, and FIG. 3 is a sectional view of another embodiment according to the present invention. 1,8 …… Disk type ferrite core, 2 …… Whetstone, 3,3a, 3b,
9,9a, 9b …… annular groove, 4 …… inner diameter, 5,11 …… stepped portion, 6
…… Chuck, 10 …… Outer diameter.

Claims (1)

[Claims] 1. A method for manufacturing a rotary transformer core comprising a disk-shaped ferrite core having a through hole in the center thereof and a plurality of concentric annular grooves formed in the main plane thereof. Of the inner peripheral surface or the outer peripheral surface of the core is held in a portion that does not reach the main plane, and a plurality of annular grooves are ground on the main plane, and A method for manufacturing a rotary transformer core, characterized in that a step is ground on the main plane side and the inner peripheral surface or the outer peripheral surface which is not held is ground.