JPH06105506A - Manufacture of coreless coil - Google Patents

Abstract

PURPOSE:To make it possible to assemble a coreless coil in a superior manner by reducing the disconnection of wires. CONSTITUTION:Initially, coil pieces 40 are substantially subjected to round molding by energization. After the round molding, the coil pieces 40 are attached at predetermined intervals to positioning pins 64 that project from a jig 62. Jigs 68, on the internal periphery of which a coated jig 66 is disposed, are fitted around the coil pieces 40. The jigs 60 and 68 are made of brass, and the jigs 62 and 66 are made of teflon. In this state, thermosetting resin is poured on the coil pieces, and all of the coil pieces are heated by a heating device such as an oven. Pressing forces designated by arrows F3 and F4 act on the coil pieces 40 because of a difference in coefficient of linear expansion between the jigs, whereby, as a whole, the coil pieces are subjected to round molding. Simultaneously, the thermosetting resin cylindrically sets, so that a coreless coil is obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a method of manufacturing a coil in a brushless motor, and more specifically, to a method of manufacturing a coreless coil suitable for a brushless motor for rotating a disk medium such as a hard disk.

[0002]

2. Description of the Related Art In a brushless motor, a coreless coil is sometimes used for reasons such as reduction of iron loss and reduction in size and weight. FIG. 5 shows an example of a brushless motor using a coreless coil. This figure shows the right half of the axial section. . In the figure, a shaft 16 is rotatably attached to a shaft 10 through bearings 12 and 14 and has a substantially U-shaped cross section that also serves as a bearing holder. The shaft 10 is continuous with the motor base 18 at the bottom, and this motor base 18 is
It is fixed to a D chassis (not shown).

Next, a disk holder 20 is formed on the lower outer periphery of the hub 16, and a hard disk 22 is fitted from above the hub. The hard disk 22 is further held by clampers 24 and 26. Access to the hard disk 22 is made on both sides by the head 28.

Next, a coreless coil 30 is provided at the bottom of the motor base 18 with an appropriate clearance with respect to the hub 16. Also, inside the hub 16,
A magnet 32 is arranged to face the coreless coil 30 with an appropriate clearance. Coreless coil 30
Is formed by resin-molding the coil piece 30A as shown in FIG. 6, and has an advantage that iron loss does not occur because it does not have a core (iron core).

When a current is passed through the coreless coil 30 while controlling the energization direction, the magnetic field generated by the coreless coil 30 and the magnetic field generated by the magnet 32 act to rotate the hub 16. As a result, the hard disk 22 rotates with respect to the head 28. The head 28 is shown in FIG.
Move left and right to access the desired track.

Such a coreless coil is conventionally manufactured by the method shown in FIG. # 7-in FIG.
A cross section along line # 7 is shown in FIG. First, the flat plate coil piece 40 of FIG. 9A is formed by winding the copper wire 42 using a winding frame or winding the copper wire 42 in an air core. Then, the coil piece 40 is set in the molding jigs 44 and 46 by the mold shown in FIG.

Then, when the jig 46 is pressed against the jig 44 as indicated by an arrow FA in the figure, the coil piece 40 follows the surface shape of the jigs 44 and 46 and is shown by a chain line in FIG. As shown in FIG. Next, as shown by an arrow FB, the jig is filled with a mold resin and a thermosetting process is performed to mold the coil piece 40, whereby the coreless coil 30 as shown in FIG. 6 is obtained.

[0008]

However, in the conventional method of manufacturing a coreless coil as described above, it is not possible to satisfactorily perform the R-molding of the coil piece, and disconnection may occur. As a result, the production efficiency is reduced, which is disadvantageous in terms of cost. The present invention focuses on these points, and an object thereof is to provide a method for manufacturing a coreless coil that can reduce disconnection and satisfactorily assemble.

[0009]

SUMMARY OF THE INVENTION One of the present inventions is a cylindrical shape obtained by combining a first step of subjecting a coil piece to a rough R-forming in a state where a temperature is raised and a material having a different linear expansion coefficient. In the jig, in which the pressing force is generated due to the difference in linear expansion coefficient when heated, the coil piece after the R molding obtained in the first step is arranged in a cylindrical shape and filled with a thermosetting resin. And a second step of performing later R molding and resin molding by heating.

According to another aspect of the present invention, there is provided a first step of subjecting a coil piece to a required R-forming in a state where a temperature is raised, and the first step on the FPC having a predetermined wiring pattern and a land portion formed thereon. A second step of mounting a required number of the obtained R-shaped coil pieces and bending the FPC into a cylindrical shape after mounting to perform resin molding is also included.

[0011]

According to one aspect of the present invention, first, the coil piece is roughly R-formed in a state where the temperature is raised by, for example, energization or blowing. Next, the R-shaped coil pieces are cylindrically arranged in a molding jig in which materials having different linear expansion coefficients, such as brass and Teflon, are combined. Then, after the thermosetting resin is filled, heat treatment is performed. Then, due to the difference in linear expansion coefficient, the coil piece is pressed and further R-shaped, and the thermosetting resin is cured.

According to another aspect of the invention, the required R-forming is performed on the coil piece while the temperature is rising. The coil piece after molding has an F formed with necessary wiring patterns and lands in advance.
It is attached to a PC. Then, after the FPC is bent into a cylindrical shape, resin molding is performed.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the method for manufacturing a coreless coil according to the present invention will be described below with reference to the accompanying drawings. It should be noted that the same reference numerals are used for the components that are the same as or correspond to the above-described conventional technique. <First Embodiment> First, a first embodiment of the present invention will be described with reference to FIGS. FIG. 7 described above
The coil piece 40 shown in (A) is first roughly R-shaped by the jig shown in FIG. In the figure, the R molding jig is a jig 5 having a concave shape and a surface having a first curvature.
0, a jig 5 having a convex surface with a second curvature
2 and. The coil piece 40 is arranged between these jigs 50 and 52. Then, the jigs 50 and 52 are moved in the direction of arrow F2 to press the coil piece 40 while energization by the power source 54 or heating with warm air shown by arrow F1.

As a result, the coil piece 40 is shown in FIG.
As shown in FIG. The degree of curvature does not necessarily have to be the final dimension. In this way, since the coil piece 40 is pressed while being heated, the occurrence of wire breakage is satisfactorily reduced. In addition, there is almost no return after molding.

Next, the coil piece 40 roughly R-shaped as described above is R-shaped by the jig shown in FIGS. 2 and 3. 2 is a cross-sectional view of the jig plane, and a cross section taken along line # 3- # 3 in FIG. 2 is shown in FIG. In these figures, a cylindrical jig 60 is provided at the center.
Is prepared, and a jig 62 is provided so as to cover the outside thereof. The jig 60 is made of a material having a relatively small linear expansion coefficient such as brass, and the jig 62 is made of a material having a relatively large linear expansion coefficient such as Teflon. There is. From the jig 62,
Positioning pins 64 for attaching the coil pieces are provided so as to project at predetermined positions.

A coil piece 40 that has been subjected to the above-described R shaping.
Are attached to the positioning pins 64 protruding from the jig 62 at predetermined intervals. Then, the jig 68, which is provided by covering the jig 66 on the inner peripheral side, is fitted around the coil piece 40. A material having a relatively large linear expansion coefficient such as Teflon is used for the jig 66, and a material having a relatively small linear expansion coefficient such as brass is used for the jig 68. Has been.

In this state, the thermosetting resin is injected into the space between the jigs 62 and 66, and the whole is heated by a heating device such as an oven. Then, first, on the inner diameter side, since the jig 62 has a larger linear expansion coefficient than the jig 60, the size of the jig 60 hardly changes.
The jig 62 expands greatly. Therefore, the jig 62 expands to the outside, that is, the coil piece 40 side, as shown by the arrow F3 in FIG.

On the other hand, on the outer diameter side, since the jig 66 has a larger linear expansion coefficient than the jig 68, the size of the jig 68 hardly changes, but the jig 66 expands greatly. Become. Therefore, the jig 66 is pushed inward, that is, toward the coil piece 40 side, as shown by an arrow F4 in FIG.

By the action of these jigs 60, 62, 66, 68, the coil piece 40 is pressed in the directions of the arrows F3, F4, and R shaping is performed as a whole. At the same time, the thermosetting resin solidifies into a cylindrical shape, so that the coreless coil shown in FIG. 6 can be obtained in a good size and shape.

Next, after molding, the coreless coil is removed from the jig. At this time, since the jigs 62 and 66 on the coil side are both formed of Teflon, there is no inconvenience such as the thermosetting resin adhering to the jigs 62 and 66. After that, natural cooling (or forced cooling) is performed, and the jig described above returns to a desired dimension after cooling. As a result, a coreless coil having a desired size can be obtained and can be easily removed from the jig.

As described above, according to the first embodiment, the temporary R forming is first performed on the coil piece in the heated state. Then, the molded coil piece is subjected to molding in a heated state and resin molding at the same time by using a jig utilizing the difference in linear expansion coefficient. For this reason, the occurrence of wire breakage is satisfactorily reduced, and the productivity is also improved.

<Second Embodiment> Next, a second embodiment of the present invention will be described with reference to FIG. In this embodiment, an FPC (Flexible Printed Circu) as shown in FIG.
it) 70 is used. Required wiring patterns such as star and delta are formed in the FPC 70.
The connection points between the ends of the coil pieces (start and end of winding)
Land portions 72 are formed.

The coil piece 40, which has been R-shaped to have a predetermined curvature by the method shown in FIG. 1, is attached to such an FPC 70 by using a double-sided tape, an adhesive or the like (see arrow F5 in the figure). Then, the end of each coil piece 40 is soldered and fixed to the corresponding land portion 72. In this way, when the FPC 70 having the coil pieces 40 attached thereto in a predetermined number is bent as shown by an arrow F6 in the figure to connect the end portions 70A and 70B to each other, and the resin molding is performed,
The coreless coil shown in FIG. 6 is obtained. Connection with a drive circuit (not shown) is performed by the lead portion 74.

According to this embodiment, since the connecting wire between the coil pieces is connected by the FPC, the connecting process and the molding process are greatly simplified, and the disconnection of the connecting wire is prevented. Further, there is an advantage that the crossover wire and the gap do not hit when the motor is incorporated.

<Other Embodiments> The present invention is not limited to the above embodiments, and includes the following, for example. In the above embodiment, the number of coil pieces is six, but the number may be changed as necessary. The wiring pattern of the FPC that connects the coil pieces may be appropriately set, such as star or delta, as necessary. Also,
The land portion that connects this wiring pattern and the end of each coil piece may be appropriately changed in circuit design. Materials other than brass and Teflon may be used as the materials having different linear expansion coefficients. The motor to which the coreless coil manufactured by applying the present invention is applied is not particularly limited, but a spindle motor or the like that rotationally drives a disk medium such as a hard disk is suitable.

[0026]

As described above, the method of manufacturing a coreless coil according to the present invention has the following effects. (1) Since the coil piece is roughly R-shaped in advance, the coil piece is attached to a jig that presses by utilizing the difference in linear expansion coefficient, and the heat treatment is performed after filling the thermosetting resin. Occurrence of disconnection is satisfactorily reduced, and productivity is also improved. (2) Since the coil pieces are subjected to the required R-molding, and they are attached to the FPC to form a cylindrical shape and then resin-molded, the connection processing between the coil pieces and the molding processing are greatly simplified and The disconnection of the crossover wire is also prevented.

[Brief description of drawings]

FIG. 1 is a first method of manufacturing a coreless coil according to the present invention.
It is explanatory drawing which shows one of the processes of an Example.

FIG. 2 is an explanatory view showing one of the steps of the first embodiment.

FIG. 3 is an explanatory view showing an end face taken along line # 3- # 3 of FIG.

FIG. 4 is an explanatory view showing one of the steps of the second embodiment of the present invention.

FIG. 5 is an explanatory diagram showing an example of a brushless motor using a coreless coil.

FIG. 6 is an explanatory diagram showing an example of a coreless coil.

FIG. 7 is an explanatory diagram showing a method of manufacturing a conventional coreless coil.

[Explanation of symbols]

40 ... Coil pieces, 50, 52, 60, 62, 66, 68
... jig, 54 ... power supply, 64 ... positioning pin, 70 ... FP
C, 70A, 70B ... End portion, 72 ... Land portion, 74 ... Lead portion.

Claims (2)

[Claims] 1. A cylindrical jig in which a first step of roughly R-forming a coil piece in a state where a temperature is raised is combined with a material having different linear expansion coefficients, and the linear jig has a linear expansion coefficient when heated. The coil piece after the R molding obtained in the first step is arranged in a cylindrical shape in a jig that generates a pressing force due to the difference of
And a second step of performing molding and resin molding. 2. A first step of subjecting a coil piece to a required R-forming while raising a temperature, and an R obtained by the first step on an FPC having a predetermined wiring pattern and a land portion formed thereon. Attach the required number of coil pieces after molding,
And a second step of bending the FPC into a cylindrical shape after mounting and resin-molding the FPC.