JPH01215199A - Manufacture of bobbin for voice coil - Google Patents

Abstract

PURPOSE:To keep roundness and to preclude possibility in deformation in a specific direction by applying braiding or cross spiral winding to lots of fibers or thin tapes onto an outer circumference of a core whose cross section is circular and fixing them by a resin to form a cylinder and cutting off the cylinder so as to obtain a bobbin. CONSTITUTION:Lots of fibers 32 or thin tapes are braided or wound crossingly in spiral onto the outer circumference of the core rod 31 whose cross section is circular, they are fixed by a resin 33 to form a cylinder 35, the cylinder 35 is cut off to a required length to obtain a bobbin 43. Thus, the lots of fibers 32 or thin tapes are formed into a cylinder and solidified by the resin 33, then no orientation of the material exists in the state of the bobbin 43. Thus, there is no possibility of deformation in a specific direction and the fibers 32 and the resin 33 are formed as a composite, then strength is obtained and roundness is endured.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method of manufacturing a bobbin used for a voice coil of a speaker.

[Conventional technology and its issues]

The voice coil of a speaker is generally manufactured as follows. First, as shown in FIG. 5A, the bobbin 12 is fitted onto the outer periphery of the cylindrical jig 11. The bobbin 12 is usually made of paper, but aluminum foil or the like may be used in some cases. The cylindrical jig 11 is used to maintain the roundness of the voice coil, position it, etc. when manufacturing the voice coil and assembling it into a speaker, and cannot be removed after it is assembled into the spinaker. be. Next, as shown in Figure B, the coil 13 is formed by winding the coated wire on the bobbin 12 in an aligned manner, and the lead portion 14 of the coil 13 is pulled out in the axial direction. The voice coil 16 fitted into the cylindrical jig 11 is completed by bonding the tape 15 so as to press down the lead part 14 near the lead part 13.

Note that the outer peripheral surface of the bobbin 12 is coated with an alcohol-soluble adhesive in advance, and when a self-bonding coated wire coated with an alcohol-based solvent is wound thereon and dried by heating, the bobbin 12 and the coil 13 are bonded together. are becoming integrated.

Now, the bobbin used for such a voice coil is conventionally manufactured in the following manner. That is, as shown in Figure 6, using two bobbin tapes 20a and 20b, one tape 20a is spirally wound so that both side edges are butted, and the other tape 20b is wrapped on top of it so that both side edges are butted. After spirally winding the butts so that the butts are shifted by half a pitch, and bonding them together with an adhesive (not shown) to form the double tube 21, cut this to the required length and attach the bobbin 12.
This is the method of obtaining.

However, the bobbin manufactured by this method has directional properties because the tape is wound diagonally, and has the disadvantage that it is easily deformed in a specific direction. Furthermore, because the double-walled tube with spirally wound tape is cut perpendicular to the axis, the tape ends at an acute angle, which has the disadvantage of making it easy to peel off.

In addition, there are also 22 punched strips as shown in Figure 7.
Wrap it around the outer periphery of a cylindrical jig (not shown) so that both ends are butted together, and then wrap the strip 22 as shown in Figure 8.
The bobbin 12 is also formed by applying an adhesive tape 24 so as to press down the abutting portions 23 of both ends of the bobbin 12 . The purpose of using a strip with rounded corners as shown in Figure 7 is to prevent the corners from turning up.

However, bobbins manufactured using this method tend to be misaligned in the axial direction at the abutting portions 23 of both ends, as shown in Figure 9, and when such misalignment occurs, the corners of the strips turn over, causing defects. . In addition, when using aluminum foil as a strip, simply wrapping it around a cylindrical jig tends to cause small bends, making it difficult to form into a smooth cylindrical shape, which requires roll forming. This has the disadvantage of high cost.

Since the voice coil is placed in a narrow cylindrical gap inside the speaker, there is a possibility that the bobbin material may turn over or become deformed.
The reduction in roundness is strictly limited.

[Means for solving problems and their effects]

An object of the present invention is to provide a new method for manufacturing a voice coil bobbin in order to solve the above problems.

In order to achieve this object, the present invention involves braiding or crisscrossing a large number of fibers or thin tape around the outer periphery of a mandrel having a circular cross section, and then hardening it with resin to form a cylindrical body. The bobbin is obtained by cutting the bobbin to the required length.

In this way, a large number of fibers or thin tapes are gathered in a cylindrical shape in a criss-crossed state and hardened with resin, so there is no directionality in the material in the bobbin state, so it deforms in a specific direction. Since it is a composite of fibers and resin, it has strength and can maintain roundness.

Note that "cross spiral winding" here means winding the fibers or tape in such a way that they intersect with each other between the inner and outer layers, and includes the case where one of the inner and outer layers is spirally wound and the other is longitudinally wound. .

〔Example〕

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

Figures IA to F illustrate an embodiment of the invention.

In the figure, reference numeral 31 denotes an upright mandrel with a circular cross section, at its lower part there is provided a part for braiding a large number of fibers 32 around the outer periphery, and at its upper part, liquid resin 33 is applied to the braided material.
There is a part where resin 3 is applied and impregnated, and the upper part is coated with resin 3.
A drawing die 34 is provided to make the amount of resin deposited uniform and to keep the outer diameter constant, and a heater 35 is provided above the drawing die 34 to heat and solidify the resin. When the resin solidifies, a cylindrical body 36 in which fibers and resin are integrated is completed. Further, on the upper part, a coating wire adhesive 3 is applied to the outer periphery of the cylindrical body 36.
7 is provided, a heater 38 for heating and drying the adhesive is provided above the section, and a heater 38 for heating and drying the adhesive is provided above it.
A lower chuck 39 that grips a portion slightly below the upper end of the cylindrical body 36, a cutter 40 that cuts the cylindrical body 36, and an upper chuck 41 that grips the vicinity of the upper end of the cylindrical body 36 are sequentially provided. A cylindrical jig 42 is arranged on the extension of the axis of the cylindrical body 36 to mount the manufactured bobbin thereon.

As the fiber 32, for example, aramid fiber (trade name: Kevlar) is used, and as the resin 33, for example, polyimide or epoxy resin is used. Further, as the adhesive 37, the same alcohol-soluble adhesive as the conventional one is used.

In the state shown in FIG. 1A, the lower chuck 39 grips the cylindrical body 36, and from this state, the lower chuck 39 and the mandrel 31 are simultaneously moved upward and the braiding machine (not shown) is rotated. As a result, &I&Il of fiber 32,
Coating, impregnating, squeezing, and heating solidification of the resin 33 and coating and drying of the adhesive 37 are performed simultaneously. When the cylindrical body 36 has risen by the length of one bobbin, the lower chuck 39 and the mandrel 31 are stopped from rising and the braiding machine is stopped from rotating. Now the state is as shown in Figure B. Next, as shown in Figure C, after gripping the upper end of the cylindrical body 36 with the upper chuck 41, the cutter 4
0 is rotated around the cylindrical body 36 and the cylindrical body 36 is cut to obtain a bobbin 43. Also, pull down the mandrel 31 to the same position as A in the figure. In order to facilitate the pulling down of the mandrel 31, it is preferable that the mandrel 31 has a slight taper so that the outer diameter becomes smaller toward the upper end.

Next, the upper chuck 41 is raised to fit the bobbin 43 into the cylindrical jig 42 as shown in the figure, and the lower chuck 39 is opened. Furthermore, the upper chuck 41 is opened as shown in the figure E, and the lower chuck 39 to the position A in the figure. Next, as shown in FIG.
grasp. After that, the cylindrical jig 4 equipped with the bobbin 43
2 is sent to the next process, for example, a coil winding process, and a new cylindrical jig is placed, returning the state to A in the figure.

Bobbins are manufactured one after another by repeating the above operations. Note that the application of the adhesive 37 may be performed before the resin is completely solidified, that is, when it is in a semi-solidified state, and the application and drying of the adhesive 37 may be performed as necessary, and may be omitted. be.

Figures 2 and 3 each show other embodiments of the present invention. The embodiment in Figure 1 shows the case where the fibers are braided, but these embodiments show the case where the fibers are cross-spirally wound. In the embodiment shown in Fig. 6-2, a large number of fibers 32 are first spirally wound in one direction around the mandrel 31 at the lower mandrel 45, and then the same fibers 32 are spirally wound in the opposite direction at the upper mandrel 46. In the embodiment shown in FIG. 3, first, a large number of fibers 32 are vertically attached around the mandrel 31 at the lower mandrel 45, and then the fibers 32 are spirally wound in one direction at the upper mandrel 46. . The subsequent steps are the same as the embodiment shown in FIG.

In each of the above embodiments, the fibers are braided or spirally wound, but it is also possible to use a thin tape instead of the fibers.

In addition, after winding the coil around the bobbin attached to the cylindrical jig,
Heat treatment may be performed, but if the thermal expansion coefficients of the bobbin and coil differ at this time, the integrity of the two may deteriorate or deform. It is preferable to make a cut 47 in the axial direction in the bobbin 43.

In this way, the bobbin can follow the thermal expansion of the coil, so the above problem can be solved. Since the bobbin manufactured by the method of the present invention is hardened with resin, the cut 4
7 will not deform.The work of making the cut 47 can be done when attaching the bobbin cut from the cylindrical body to the cylindrical jig (when going from IC to D in Figure). .

〔Effect of the invention〕

As explained above, according to the present invention, it is possible to obtain a bobbin in which a large number of fibers or thin tapes are assembled in a cylindrical shape in a crossed state and hardened with resin, and this bobbin is made of resin and fibers. Or, since it is a composite with tape, it has moderate strength and can maintain its roundness by itself.
It has excellent advantages such as there is no risk of deformation in a specific direction because the material has no directionality.

[Brief explanation of the drawing]

Figures IA to F are explanatory diagrams showing a method for manufacturing a voice coil bobbin according to one embodiment of the present invention, Figures 2 and 3 are explanatory diagrams showing other embodiments of the present invention, and Figure 4 1 is a perspective view showing an example of a bobbin manufactured according to the present invention,
5A to 5C are explanatory diagrams and diagrams showing the voice coil manufacturing method.
6 is an explanatory diagram showing an example of a method for manufacturing a conventional voice coil bobbin, FIG. 7 is a plan view of a strip used in a conventional voice coil bobbin, and FIG. 8 is an example of a conventional voice coil bobbin. FIG. 9 is a perspective view showing problems with the bobbin. 31: Mandrel, 32: Fiber, 33: Resin, 34: Drawing die, 35: Cylindrical body, 37: Adhesive, 39: Lower chuck, 40: Cutter, 41: Upper chuck, 42: Cylindrical jig, 43 : Bobbin. Figure-1Δ Figure-Old Figure-IC Figure-10 Figure-IE Figure-IE Figure-2 Figure-3

Claims (1)

[Claims] 1. A large number of fibers or thin tapes are braided or crossed spirally wound around the outer periphery of a mandrel with a circular cross section, and then hardened with resin to form a cylindrical body, and the cylindrical body can be used as needed. A method of manufacturing a bobbin for a voice coil, the method comprising obtaining a bobbin by cutting the bobbin to a desired length. 2. The method according to claim 1, characterized in that the adhesive for the coated wire for the coil is applied before or after the resin is solidified.