JPH07274469A - Voice coil motor coil fixing method - Google Patents

Abstract

PURPOSE:To provide a voice coil motor coil fixing method which requires a less number of assembling processes and assures stable quality. CONSTITUTION:An arm body 1 consisting of a thermosetting resin and an almost polygonal coil 4 are integrated by providing a recess or a hole for inserting a heater terminal to a coil built-in part 3 of the arm body 1 and then a part of the coil built-in part 3 of the arm body 1 is thermally clamped to the side surface of coil.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a coil fixing method for a voice coil motor used in magnetic disk devices, optical disk devices and the like.

[0002]

2. Description of the Related Art In recent years, magnetic disk devices and optical disk devices have been reduced in price and downsized, and accordingly, a drive device for positioning a magnetic head and an optical head on a target track on a disk has a simple structure. Therefore, a rotary voice coil motor with a small layout area has been adopted.

First, the structure and operating principle of a rotary voice coil motor (hereinafter referred to as VCM) in a magnetic disk device will be described as an example. As shown in FIGS. 7, 8 and 9, the VCM includes an upper yoke 23, a lower yoke 24,
Magnet 25a for generating a magnetic field of N pole, magnet 25b for generating a magnetic field of S pole, coil 4 having a substantially polygonal shape, arm body 1
The rotary bearing 26 holds the rotary body 26 and the suspension 22 for mounting the arm 1 and the magnetic head 21 on the rotary bearing 26, and the yoke set screw 27 fixes the upper and lower yokes.

When the magnetic head 21 moves to a desired data track on the disk 20, the direction and magnitude of the current flowing through the coil 4 is controlled by a VCM control circuit (not shown), and the current i is supplied to the coil 4. A magnetic field corresponding to is generated. Magnetic fields of different polarities are generated at the overlapping portions a and b of the coil 4 and the magnet 23a and the magnet 23b, so that the coil 4 is repelled or attracted in the same rotation direction,
The magnetic head 21 can be moved to a target data track by rotating the arm body 1 carrying the coil 4 around the rotary bearing 26. In order to obtain a sufficient thrust, it is desirable that the coil 4 be as close to the upper yoke 23 and the magnets 25a and 25b as possible. In consideration of the shape accuracy of each component, the coil 4 is generally a magnet 25a and a magnet 25.
It is arranged with a gap of about 0.3 mm between b and the upper yoke 23.

The material of the arm body 1 is required to be light in order to move the magnetic head 21 to a target track at high speed, and to have high rigidity so as not to resonate with the moving operation. For this reason, the arm body 1 was conventionally formed by machining an aluminum die-cast molded product,
In recent years, for low cost, the molding temperature is lower than that of aluminum, the molding is easy, the shape accuracy after molding is good, and the one formed by injection molding of thermoplastic resin which does not require machining is adopted. .

For the coil 4, a wire is used in which a copper wire is coated with an insulating material and an adhesive that is welded by heat and a solvent. The coil 4 is formed by using a jig for defining the inner shape of the coil 4 and the thickness of the coil 4, and applying an adhesive agent while blowing hot air on the wire material with a winding machine or applying a solvent. It is formed by welding and winding a predetermined number of turns. Detailed description and figures are omitted.

Next, a method of fixing the coil 4 to the arm body 1 will be described. In the conventional method, a method is generally used in which an aluminum-based die-cast or a thermoplastic resin is used and an epoxy adhesive is used. Here, the coil 4 is bonded to the thermoplastic resin arm body 1. Will be described.

As shown in FIG. 9, an arm assembly 5 made of a thermoplastic resin comprises an arm body 1 and a coil 4. 2 between the coil assembly portion 3 of the arm body 1 and the outer shape of the coil 4.
The clearance of 0.1 mm to 0.2 mm is set so that the shape tolerance of the two parts does not cause a problem that the coil 4 is not incorporated in the arm body 1. Further, the coil assembly portion 3 of the arm body 1 is provided with adhesive agent reservoirs 30a to 30d so that the adhesive agent can be easily applied.

Next, the bonding process will be described including a jig. First, as shown in FIG. 10, the arm body 1 and the coil 4 are set on the bonding jig 32. The arm body 1 is a rotary bearing 26.
The positioning is performed by the mounting hole 2 and the positioning pin 11a, the outer shape of the coil mounting portion 3 and the positioning pins 11b and 11c, and the coil 4 is positioned by the inner shape of the coil mounting portion 3 of the arm body 1. The adhesive application is performed by a device called a dispenser 34, which can control the application amount constant. In FIG. 10, the robot 13 is provided with a dispenser 3
In the example shown in FIG. 4, the adhesive application terminals 35a to 35d from which the adhesive flows out are positioned by the robot 13 on the adhesive reservoirs 30a to 30d of the arm body 1. The control box 12 controls the positioning of the adhesive application terminals 35a to 35d and the application amount of the adhesive.

As shown in FIGS. 11 and 12, when the adhesive 36 is applied to the adhesive reservoirs 30a to 30d, the adhesive 36 flows into the gap 37 between the arm body 1 and the coil 4, and the cure (drying) described later is performed. A sufficient fixing force can be obtained by being cured in the process. The curing step is performed by storing the arm assembly 5 still set in the bonding jig 32 in a drying oven in which the temperature inside the oven is kept constant. The curing time is generally 30 minutes to 2 hours. Although illustration is omitted, the coil 4 and the arm body 1 are displaced from each other in the height direction during the curing, and the coil 4 is V-shaped.
After the CM is assembled, a weight is placed on the coil 4 so that the coil 4 does not come into contact with the upper yoke 23 and the magnets 25a and 25b to cause a malfunction, so that the positional displacement of the arm body 1 and the coil 4 in the height direction is prevented. There is.

[0011]

However, in the method of fixing the arm body 1 and the coil 4 by the above-mentioned adhesion, the adhesion cure for positioning the arm body 1 and the coil 4 in the curing process after the adhesive application. Not only does the tool 32 need to be provided in the same number as the arm assembly 5 during the curing process,
It requires man-hours for the curing process.

Also, during the curing process, if the adhesive 36 flows out and jumps out from the lower surface of the arm body 1 and hardens, or the adhesive 36 is applied too much and rises above the upper surface of the arm body 4 and hardens. The cured adhesive 36 comes into contact with the upper yoke 23 and the magnets 25a and 25b, which causes malfunction of the arm assembly 5.

Further, in the magnetic disk drive, the gas generated from the adhesive 36 may deteriorate the protective film or the magnetic film of the magnetic disk 20 to cause a fatal quality problem that data cannot be read or written. Yes,
It was a method with many drawbacks.

Therefore, an object of the present invention is to provide a method for fixing a coil of a VCM which does not use an adhesive, does not require a curing step, and has stable quality.

[0015]

In order to achieve the above object, in the coil fixing method of the present invention, an arm body made of a thermoplastic resin and having a polygonal coil assembly portion and a coil are provided. Is partially fixed to the side surface of the coil by thermocompression bonding.

[0016]

Embodiments of the present invention will be described below with reference to the drawings. 1 is a perspective view showing an arm assembly in a first embodiment of the present invention, FIG. 2 is a perspective view showing an arm assembly in a second embodiment of the present invention, and FIG. 3 is an embodiment of the present invention. FIG. 4 is a perspective view of a crimping device and a crimping jig used in FIG. 4, FIG. 4 is a sectional view showing a state in which the arm body and the coil are incorporated in the crimping jig, and FIG. It is sectional drawing which shows a state. Description of the same parts as those of the conventional example will be omitted.

The first embodiment shown in FIG. 1 has a structure in which the coil assembly portion 3 of the arm body 1 made of a thermoplastic resin holds the outer shape of the coil 4. In FIG. 1, the coil assembly portion 3 of the arm body 1 is provided with thermocompression bonding portions 3a to 3d, and the side surface of the coil 4 on the outer shape side is thermocompression bonded and fixed. The width of the coil assembly portion 3 is set to be wide enough to secure the strength. On the other hand, the width of the thermocompression bonding portions 3a to 3c must be narrower than the width of the coil assembly portion 3 in order to reduce the amount of heat applied to the thermocompression bonding portions 3a to 3c as much as possible and to shorten the thermocompression bonding time. In order to realize this, the thermocompression bonding portions 3a to 3c are formed in a concave shape with respect to the outer shape of the coil incorporating portion 3 so that the heater terminal 14a can be inserted. Further, the thermocompression bonding part 3d has a hole for inserting the heater terminal 14a in the arm body 1, and
Similar to a to 3c, the width of the thermoplastic resin is set to be appropriate for thermocompression bonding. Thermocompression bonding parts 33a to 33d
The height of the is set beforehand so that the thermoplastic resin is not pushed out to the upper and lower surfaces of the arm body during the thermocompression bonding and pops out from the upper and lower surfaces to cause a malfunction.

The second embodiment shown in FIG. 2 has a structure in which the coil assembly portion 3 of the arm body 1 made of a thermoplastic resin holds the inner shape of the coil 4. In FIG. 1, the coil assembly portion 3 of the arm body 1 is provided with thermocompression bonding portions 3a to 3c, and although not shown, a non-penetrating hole and a thermocompression bonding portion are provided on the lower surface side near the assembly hole 2. The side surface of the coil 4 on the inner shape side is fixed by thermocompression bonding. The thermocompression bonding parts 3a to 3c have a hole for inserting the heater terminal 14a in the arm body 1, and like the first embodiment, the width and height of the thermoplastic resin are suitable for thermocompression bonding. Is set to

Next, the first embodiment will be described in more detail including a thermocompression bonding process and a jig. First, as shown in FIG. 3, the arm body 1 and the coil 4 are set on the thermocompression bonding jig 10. Thermocompression bonding heats the heater terminals 14a to 14d,
This is performed by the heater unit 14 having a function of applying an appropriate pressing force to the thermocompression bonding portions 3a to 3d. FIG. 3 shows an example in which the heater unit 14 is incorporated in the robot 13, and the heater terminals 14a to 14d are positioned by the robot 13 on the side surfaces of the thermocompression bonding portions 3a to 3d of the arm body 1. The temperature and position of the heater terminal 14a are controlled by the control box 12.
In FIG. 4, the heater terminals 14b and 14d are attached to the thermocompression bonding portions 3b and 3d.
It is an AA sectional view showing the state where it was positioned to the d side part.

Thereafter, the heater terminal 14d moves in the direction of the arrow in FIG. 5 and presses the thermocompression bonding portion 3d against the side surface of the coil 4 with an appropriate pressing force to soften the thermoplastic resin. As a result, the gap 37 set so that the coil 4 can be installed in the coil assembly portion 3 of the arm body 4 is filled with the softened thermoplastic resin. After that, the heater terminal 14d moves in the direction opposite to the direction of the arrow in FIG. 5, the resin of the thermocompression bonding portion 3d cools and solidifies, and the coil 4 is fixed to the arm body 1. At this time, the solidified thermoplastic resin fills the details of the uneven portion of the wire section of the coil 4 as shown in FIG. 6, so that a sufficient fixing force can be obtained. Further, the time required for solidifying the thermoplastic resin can be suppressed within a few seconds by setting the volume of the thermocompression bonding portion 3d small, and it is possible with the thermocompression bonding jig 10 set in the robot 13. Is. Therefore, a plurality of thermocompression bonding jigs 10 are not required.

The thermocompression bonding temperature of the thermoplastic resin is 35 in the case of polyether imide containing 20% to 30% of glass fiber.
0 ° C. to 360 ° C., and in the case of polyphenylene sulfide containing 40% of glass fiber, about 280 ° C. is appropriate.

[0022]

According to the method of fixing the voice coil motor of the present invention, the coil is fixed to the arm body made of thermoplastic resin by thermocompression bonding without using an adhesive. This eliminates the need for a curing process to dry the adhesive,
No jig is needed to position the coil and arm during the curing process. This significantly shortens the process and reduces the jig manufacturing cost.

Also, during the curing process, the adhesive flows out, and then pops out from the upper and lower surfaces of the arm body and is solidified, so that the adhesive does not come into contact with the upper yoke and the magnet and the arm body does not malfunction. Further, in the magnetic disk device, no gas is generated which would be a problem when an adhesive is used, which remarkably contributes to the improvement of reliability.

[Brief description of drawings]

FIG. 1 is a perspective view showing an arm assembly of a voice coil motor according to a first embodiment of the invention.

FIG. 2 is a perspective view showing an arm assembly of a voice coil motor according to a second embodiment of the present invention.

FIG. 3 is a perspective view showing an example of a thermocompression bonding device and a thermocompression bonding jig.

FIG. 4 is a cross-sectional view showing an arm body and a coil set on a thermocompression bonding jig.

FIG. 5 is a cross-sectional view showing an arm body and a coil before thermocompression bonding.

FIG. 6 is a cross-sectional view showing an arm body and a coil after thermocompression bonding.

FIG. 7 is a plan view showing a magnetic disk device.

FIG. 8 is a perspective view showing a voice coil motor of the magnetic disk device.

FIG. 9 is a perspective view showing an arm assembly according to a fixing method using an adhesive.

FIG. 10 is a perspective view showing an example of a bonding device and a bonding jig.

FIG. 11 is a cross-sectional view showing an arm body and a coil before bonding.

FIG. 12 is a cross-sectional view showing an arm body and a coil after adhesion.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Arm body 2 Assembly hole 3 Coil assembly part 3a, 3b, 3c, 3d Thermocompression bonding part 4 Coil 5 Arm assembly 10 Thermocompression bonding jig 14 Heater unit 14a, 14b, 14c, 14d Heater terminal 20 Disk 22 Suspension 21 Magnetic head 23 Upper yoke 24 Lower yoke 25a Magnet 25b Magnet 26 Rotating bearing 30a, 30b, 30c, 30d Adhesive agent reservoir 32 Adhesive jigs 35a, 35b, 35c, 35d Adhesive coating terminal 36 Adhesive

Claims (2)

[Claims] 1. A method for fixing a coil in an arm assembly, which comprises an arm body made of a thermoplastic resin and having a polygonal coil assembly portion, and a coil engaged with the coil assembly portion. A coil fixing method for a voice coil motor, characterized in that a part of the incorporated portion is thermocompression bonded to the side surface of the coil. 2. A recess or a hole is provided in the coil mounting portion, a heater terminal is inserted into the recess or the hole, and a part of the coil mounting portion is thermocompression bonded to the coil side surface. 1. A method for fixing a coil of a voice coil motor according to 1.