Title:
Ultrasonic crimping apparatus, crimping member, ultrasonic crimping method and arm production method
Kind Code:
A1


Abstract:
The ultrasonic crimping apparatus of the invention includes: a supporting section that supports a crimped object having a crimped section with a through hole formed therein; a crimping member in a bar shape that is smaller toward a front end thereof and larger toward a rear end thereof; a driving section that causes the crimping member to be inserted in the through hole, first from the front end thereof; an ultrasonic application section that applies ultrasonic wave to the crimping member, thereby causing radial displacement of the crimping member; and a crimping control section that causes the crimping member to be inserted into the through hole of the crimped object, while causing application of ultrasonic wave to the crimping member, thereby causing the crimped section of the crimped object to be crimped.



Inventors:
Matsumura, Takayoshi (Kawasaki, JP)
Ishikawa, Naoki (Kawasaki, JP)
Kira, Hidehiko (Kawasaki, JP)
Application Number:
11/698058
Publication Date:
03/27/2008
Filing Date:
01/26/2007
Assignee:
FUJITSU LIMITED (Kawasaki, JP)
Primary Class:
Other Classes:
G9B/5.148
International Classes:
B21D39/00; G11B21/16
View Patent Images:



Primary Examiner:
JONES, DAVID B
Attorney, Agent or Firm:
KRATZ, QUINTOS & HANSON, LLP (WASHINGTON, DC, US)
Claims:
What is claimed is:

1. An ultrasonic crimping apparatus comprising: a supporting section that supports a crimped object having a crimped section with a through hole formed in the crimped section; a crimping member in a bar shape that is smaller toward a front end thereof and larger toward a rear end thereof; a driving section that causes the crimping member to be inserted in the through hole of the crimped object supported by the supporting section, first from the front end of the crimping member; an ultrasonic application section that applies ultrasonic wave to the crimping member, thereby causing radial displacement of the crimping member; and a crimping control section that causes the crimping member to be inserted into the through hole of the crimped object, while causing application of ultrasonic wave to the crimping member, thereby causing the crimped section of the crimped object to be crimped.

2. The ultrasonic crimping apparatus according to claim 1, wherein the supporting section supports a crimped object having a plurality of crimped sections with a plurality of through holes formed in the crimped sections such that the through holes are aligned to enable the crimping member to be inserted into the through holes simultaneously, and the crimping control section causes the crimping member to be inserted into the through holes, while causing application of ultrasonic wave to the crimping member, thereby causing the crimped sections to be crimped simultaneously.

3. The ultrasonic crimping apparatus according to claim 2, wherein the crimping member has a maximum thickness area that is uniform in thickness over a predetermined length and that has a maximum thickness to be inserted into the through holes, and the crimping control section causes the driving section to make the crimping member inserted into the through holes until the maximum thickness area of the crimping member is inserted through the through holes.

4. The ultrasonic crimping apparatus according to claim 1, wherein the crimping member has a first section and a second section that are formed alternatively in the crimping member in a longitudinal direction, when ultrasonic wave is applied to the crimping member, the first section having minimum radial displacement of the crimping member, the second section having maximum radial displacement of the crimping member and further having a uniform thickness area where thickness of the crimping member is uniform over a predetermined length.

5. A crimping member that crimps a crimped object having a crimped section with a through hole formed in the crimping section, and that is inserted through the through hole and thereby crimps the crimped section, wherein: the crimping member is in a bar shape that is smaller toward a front end thereof and larger toward a rear end thereof; and the crimping member has an ultrasonic vibrator that is disposed at the rear end of the crimping member and that vibrates in response to application of a voltage of a frequency equal to ultrasonic wave.

6. The crimping member according to claim 5, wherein the crimping member has a maximum thickness area that is uniform in thickness over a predetermined length and that has a maximum thickness to be inserted into the through hole, the maximum thickness area being formed at the rear end of the crimping member.

7. The crimping member according to claim 5, wherein the crimping member has a first section and a second section that are alternatively formed in the crimping member in the longitudinal direction, when ultrasonic wave is applied to the crimping member, the first section having minimum radial displacement of the crimping section, the second section having maximum radial displacement of the crimping section and further having a uniform thickness area where thickness of the crimping member is uniform over a predetermined length.

8. An ultrasonic crimping method comprising the steps of: preparing a crimping member in a bar shape that is smaller toward a front end thereof and larger toward a rear end thereof and is displaced radially in response to application of ultrasonic wave; and inserting the crimping member, first from the front end thereof, into a though hole formed in a crimped section of a crimped object while applying ultrasonic wave to the crimping member, thereby crimping the crimped section of the crimped object.

9. The ultrasonic crimping method according to claim 8, wherein the crimping member has a maximum thickness area that is uniform in thickness over a predetermined length and that has a maximum thickness to be inserted into the through hole, the maximum thickness area being formed at the rear end, the crimped object has a plurality of crimped sections with a plurality of through holes formed in the crimped sections, the through holes are aligned so that the crimping member can be inserted into the through holes simultaneously, and the crimping member is inserted, first from the front end thereof, into the through holes until the maximum thickness area of the crimping member passes through the though holes, thereby crimping the crimped sections simultaneously.

10. A method of producing an arm of a disk apparatus, the arm including: a carriage whose front end is rotatably moved along and above a surface of a disk in a radial direction of the disk; and a suspension that extends from the front end of the carriage and whose rear end is fixed to the front end of the carriage and whose front end is provided with a head that accesses the disk, the head being positioned so as to access the disk, the method comprising the steps of: preparing a crimping member that is smaller toward a front end thereof and larger toward a rear end thereof and is displaced radially in response to application of ultrasonic wave; aligning a first through hole formed in the front end of the carriage with a second through hole formed in the rear end of the suspension; and inserting the crimping member into the aligned first and second through holes first from the front end of the crimping member, while applying ultrasonic wave to the crimping member, thereby crimping the suspension onto the carriage.

11. A crimped object comprising: a crimped section with a through hole formed in the crimping section, wherein the crimped section is crimped by inserting a crimping member into the though hole first from a front end of the crimping member, while applying ultrasonic wave to the crimping member, thereby crimping the crimping section, the crimping member being in a bar shape that is smaller toward the front end thereof and larger toward a rear end thereof and is displaced radially in response to application of ultrasonic wave.

Description:

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an ultrasonic crimping apparatus that crimps a crimped object with a crimped section by using ultrasonic wave, a crimping member, an ultrasonic crimping method and an arm production method for producing an arm of a disk apparatus.

2. Description of the Related Art

Amid the advanced information-oriented society, the amount of information is steadily increasing. In such circumstances, development of a recording format and a recording apparatus of super-high recording density is long awaited. Especially, a disk apparatus in which information access is preformed by applying light or a magnetic field onto a rotating disk is attracting attention because of its information-rewritable capacity. Thus, research and development for a larger-capacity and miniaturized disk apparatus is vigorously conducted.

Typically, a disk apparatus has plural disks and plural heads for performing information access to the respective disks in order to improve recording capacity as well as speed up information access. In such a disk apparatus, it is important to suppress unevenness in access precision of the respective heads and thus to make the floating quantity of the heads from the respective disks uniform.

In a typical method of moving a head, a head is adhered onto the front end of the respective suspensions that are each fixed to a carriage, which is caused to rotate above and along a surface of a disk, thereby moving the heads integrally. Japanese Patent Laid-Open No. 2004-127491, for example, discloses the technique that a suspension is fixed to a carriage by using an ultrasonic horn with a bulb attached to its end.

FIG. 1 illustrates a carriage assembly and how to fix a suspension to a carriage.

A carriage assembly 10 is composed of a carriage 11 that rotates above and along a surface of a disk, and a suspension 12 with a head 13 adhered onto its end. Through holes 11a and 12a are formed respectively in a front end of the carriage 11 and a rear end of the suspension 12. Crimping of the through holes 11a and 12a fixes the suspension 12 to the front end of the carriage 11. Although FIG. 1 shows a single suspension, in fact, plural suspensions are fixed to the carriage and the head 13 is adhered onto each of the suspensions.

A crimping apparatus 20 that performs crimping to the carriage assembly 10 is composed of an ultrasonic horn 22, a vibrator 21 and a moving mechanism (not shown) for moving the ultrasonic horn 22 toward the carriage assembly 10. The ultrasonic horn 22 has a bulb 23 that is formed at its end and is larger than the through holes 11a and 12a respectively of the carriage 11 and suspension 12. The vibrator 21 applies ultrasonic wave to the ultrasonic horn 22, thereby causing the ultrasonic horn 22 to contract and expand in the longitudinal direction.

At first, the carriage 11 and the suspension 12 are held such that the respective through holes 11a and 12a are aligned. The bulb 23 of the ultrasonic horn 22 is then positioned to the aligned through holes 11a and 12a. Subsequently, the vibrator 21 applies ultrasonic wave to the ultrasonic horn 22, thereby causing the ultrasonic horn 22 to contract and expand in the longitudinal direction. Then, the ultrasonic horn 22 is moved toward the carriage assembly 10 to insert the bulb 23 into the through holes 11a and 12a respectively of the carriage 11 and the suspension 12. Consequently, the through holes 11a and 12a are crimped, thereby fixing the suspension 12 to the carriage 11.

However, according to the technique disclosed in Japanese Patent Laid-Open No. 2004-127491, as the bulb 23 is forcibly inserted into the through holes 11a and 12a, the suspension 12 of a thin plate is likely to be deformed. Accordingly, the suspension 12 may be fixed to the carriage 11 in the state of being bent with respect to the carriage 11, leading to fluctuations in the floating amount of the head 13 from the disk and resulting in degraded precision of information access.

Such a problem is not limited to the case in which a suspension with a head adhered thereon is fixed to a carriage, but also generally applied to a crimping apparatus that crimps a crimped object having a crimping section.

SUMMARY OF THE INVENTION

The present invention has been made in view of the above circumstances, and provides an ultrasonic crimping apparatus, a crimping member, an ultrasonic crimping method and an arm production method that can securely crimp a crimped object while suppressing deformation of the crimped object.

An ultrasonic crimping apparatus according to the invention has:

a supporting section that supports a crimped object having a crimped section with a through hole formed in the crimped section;

a crimping member in a bar shape that is smaller toward a front end thereof and larger toward a rear end thereof;

a driving section that causes the crimping member to be inserted in the through hole of the crimped object supported by the supporting section, first from the front end of the crimping member;

an ultrasonic application section that applies ultrasonic wave to the crimping member, thereby causing radial displacement of the crimping member; and

a crimping control section that causes the crimping member to be inserted into the through hole of the crimped object, while causing application of ultrasonic wave to the crimping member, thereby causing the crimped section of the crimped object to be crimped.

According to the ultrasonic crimping apparatus of the invention, the crimping member is inserted into the through hole of the crimped object, first from the smaller front end than the rear end, while being displaced radially. Accordingly, the through hole of the object is gradually enlarged radially, which prevents deformation of the crimped object.

In the ultrasonic crimping apparatus according to the invention, the supporting section may support a crimped object having a plurality of crimped sections with a plurality of through holes formed in the crimped sections such that the through holes are aligned to enable the crimping member to be inserted into the through holes simultaneously, and

the crimping control section causes the crimping member to be inserted into the through holes, while causing application of ultrasonic wave to the crimping member, thereby causing the crimped sections to be crimped simultaneously.

The above feature of the ultrasonic crimping apparatus enables precise and efficient crimping of plural crimped sections.

Additionally, the crimping member may have a maximum thickness area that is uniform in thickness over a predetermined length and that has a maximum thickness to be inserted into the through holes, and

the crimping control section causes the driving section to make the crimping member inserted into the through holes until the maximum thickness area of the crimping member is inserted through the through holes.

Crimping the plural crimped sections finally at the maximum thickness area that has uniform maximum thickness suppresses fluctuations in crimped state among the crimped sections.

Preferably, the crimping member has a first section and a second section that are formed alternatively in the crimping member in a longitudinal direction, when ultrasonic wave is applied to the crimping member, the first section having minimum radial displacement of the crimping member, the second section having maximum radial displacement of the crimping member and further having a uniform thickness area where thickness of the crimping member is uniform over a predetermined length.

As the uniform thickness area is formed in the side section of the maximum radial displacement, the crimped section is efficiently crimped.

Additionally, a crimping member according to the invention crimps a crimped object having a crimped section with a through hole formed in the crimping section, and is inserted through the through hole and thereby crimps the crimped section, wherein:

the crimping member is in a bar shape that is smaller toward a front end thereof and larger toward a rear end thereof; and

the crimping member has an ultrasonic vibrator that is disposed at the rear end of the crimping member and that vibrates in response to application of a voltage of a frequency equal to ultrasonic wave.

Gradual crimping of the crimped object prevents deformation of the crimped object.

The crimping member according to the invention may have a maximum thickness area that is uniform in thickness over a predetermined length and that has a maximum thickness to be inserted into the through hole, the maximum thickness area being formed at the rear end of the crimping member.

As the maximum thickness area is formed at the rear end of the crimping member, it is possible to evenly perform precise crimping to the crimped object with the plural through holes.

Preferably, the crimping member has a first section and a second section that are alternatively formed in the crimping member in the longitudinal direction, when ultrasonic wave is applied to the crimping member, the first section having minimum radial displacement of the crimping section, the second section having maximum radial displacement of the crimping section and further having a uniform thickness area where thickness of the crimping member is uniform over a predetermined length.

Provision of the uniform thickness area in the second section enables efficient crimping of the crimped object.

An ultrasonic crimping method according to the invention has the steps of:

preparing a crimping member in a bar shape that is smaller toward a front end thereof and larger toward a rear end thereof and is displaced radially in response to application of ultrasonic wave; and

inserting the crimping member, first from the front end thereof, into a though hole formed in a crimped section of a crimped object while applying ultrasonic wave to the crimping member, thereby crimping the crimped section of the crimped object.

The ultrasonic crimping method of the invention prevents deformation of the crimped object, thereby performing precise crimping of the crimped object.

Further, in the ultrasonic crimping method, the crimping member may have a maximum thickness area that is uniform in thickness over a predetermined length and that has a maximum thickness to be inserted into the through hole, the maximum thickness area being formed at the rear end, the crimped object has a plurality of crimped sections with a plurality of through holes formed in the crimped sections, the through holes are aligned so that the crimping member can be inserted into the through holes simultaneously, and the crimping member is inserted, first from the front end thereof, into the through holes until the maximum thickness area of the crimping member passes through the though holes, thereby crimping the crimped sections simultaneously.

The above method enables precise crimping of the crimped object even with plural through holes formed therein.

A method of producing an arm of a disk apparatus according to the invention, the arm including: a carriage whose front end is rotatably moved along and above a surface of a disk in a radial direction of the disk; and a suspension that extends from the front end of the carriage and whose rear end is fixed to the front end of the carriage and whose front end is provided with a head that accesses the disk, the head being positioned so as to access the disk, the method including the steps of:

preparing a crimping member that is smaller toward a front end thereof and larger toward a rear end thereof and is displaced radially in response to application of ultrasonic wave;

aligning a first through hole formed in the front end of the carriage with a second through hole formed in the rear end of the suspension; and

inserting the crimping member into the aligned first and second through holes first from the front end of the crimping member, while applying ultrasonic wave to the crimping member, thereby crimping the suspension onto the carriage.

In manufacturing a disk apparatus, it is required to fix a suspension with a head formed at the front end thereof accurately to the front end of the carriage. According to the arm production method of the invention, it is possible to prevent deformation of the suspension, thereby securely fixing the suspension to the carriage. Therefore, a disk apparatus in which the arm production method of the invention is applied can accurately access a disk.

Incidentally, the arm production method described above is of only the basic mode in order to avoid redundancy. However, the arm production method is not limited to the above description, but can be applied to various modes corresponding to the modes of the ultrasonic crimping apparatus.

Additionally, a crimped object according to the invention including:

a crimped section with a through hole formed in the crimping section,

wherein the crimped section is crimped by inserting a crimping member into the though hole first from a front end of the crimping member, while applying ultrasonic wave to the crimping member, thereby crimping the crimping section, the crimping member being in a bar shape that is smaller toward the front end thereof and larger toward a rear end thereof and is displaced radially in response to application of ultrasonic wave.

As mentioned above, the present invention prevents deformation of the crimped object and enables secure crimping of the crimped object.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates how to fix a suspension to a carriage.

FIG. 2 shows a hard disk apparatus manufactured by applying one embodiment of the present invention.

FIG. 3 is an exploded perspective view of a carriage and a suspension.

FIG. 4 is a side view of the suspension and the carriage.

FIG. 5 is a schematic diagram of an ultrasonic crimping apparatus of the embodiment.

FIG. 6 is a graph showing amplitudes of an ultrasonic horn of the embodiment.

FIG. 7 shows the analysis result of radial displacement in the ultrasonic horn.

FIG. 8 illustrates a principle of crimping processing by using the ultrasonic horn.

FIG. 9 is a schematic view illustrating a part of the front end of an ultrasonic horn of a second embodiment.

FIG. 10 illustrates crimping processing using the ultrasonic horn of the second embodiment.

DETAILED DESCRIPTION OF THE INVENTION

Embodiments of the present invention will be described below with reference to the attached drawings.

FIG. 2 shows a hard disk apparatus 100 manufactured by applying one embodiment of the present invention.

The hard disk apparatus 100 shown in FIG. 2 is used by being connected to or incorporated in a host apparatus typified by a personal computer.

A housing 101 of the hard disk apparatus 100 accommodates: a magnetic disk 200 for recording information therein; a spindle motor 110 for rotating the magnetic disk 200; a magnetic head 120 (see FIG. 4) for approaching and facing a surface of the magnetic disk 200; a carriage assembly 130 that has the magnetic head 120 adhered onto the front end thereof and moves above and along the surface of the magnetic disk 200 around an arm shaft 131 thereof; a voice coil motor 140 for driving the carriage assembly 130; and a control circuit 150 for controlling the operation of the hard disk apparatus 100. The hard disk apparatus 100 serves for recording information to and reading information from the magnetic disk 200 by using the magnetic field of the magnetic head 120.

The magnetic disk 200 has linear trucks formed on the surface thereof which are divided into plural sectors along the circumferential direction of the trucks. In the hard disk apparatus 100, a series of logic addresses are assigned to the respective sectors.

The carriage assembly 130 further has a carriage 132 driven by the voice coil motor 140 and a suspension 133 with the magnetic head 120 adhered onto the front end thereof. The carriage 132 and the suspension 133 are connected to each other at a joining section 134.

Incidentally, the hard disk apparatus 100 is mounted with plural magnetic disks 200, front and back surfaces of which are each accessed by the respective magnetic heads 120. In other words, the hard disk apparatus 100 has the plural suspensions 133 which each have the magnetic head 120 attached to the front end thereof and assigned to each of the front and back surfaces of the magnetic disks 200. The plural suspensions 133 are connected to the carriage 132, so that the plural magnetic heads 120 are moved integrally.

In writing information to the magnetic disk 200, a host apparatus (not shown) sends to the hard disk apparatus 100 information to be recorded in the magnetic disk 200 together with a logic address for a writing position. The logic address is converted by the control circuit 150 into a physical address constituted by: a cylinder number representing which truck of the plural trucks on the magnetic disk 200 is a target; a head number representing which magnetic head of the plural magnetic heads is a target; and a sector number representing which sector of the plural sectors on the trucks is a target. The control circuit 150 also drives the spindle motor 110 to rotate the magnetic disk 200 as well as the voice coil motor 140 to move the carriage 132 to a position above the truck represented by the cylinder number of the physical address. The magnetic head 120 is moved, relative to the rotating magnetic disk 200, to a position above the sector represented by the sector number of the physical address, so that the magnetic head 120 is positioned above the magnetic disk 200.

In addition to positioning of the magnetic head 120, the control circuit 150 applies electric current carrying write information to the magnetic head 120 represented by the head number of the physical address.

The magnetic field in accordance with the electric current is generated by a coil provided in the magnetic head 120. The magnetic flux in accordance with the magnetic field is directed to the magnetic disk 200, so that the magnetization of the direction according to the write information can be formed on the magnetic disk 200 and the write information is recorded in the magnetic disk 200.

In reading information recorded in the magnetic disk 200, the host apparatus (not shown) sends to the hard disk apparatus 100 a logic address of a recording position where information is recorded. Subsequently, the control circuit 150, as in writing information, drives the spindle motor 110 to rotate the magnetic disk 200 and the voice coil motor 140 to move the carriage 132, so that the magnetic head 120 is positioned above the magnetic disk 200.

The reproduction signal in accordance with the magnetic field generated by magnetization is produced and is converted into digital data to be sent to the host apparatus via the control circuit 150.

Based on the above mentioned mechanism, information access is performed with respect to the magnetic disk 200.

It should be noted that a distance (i.e., the floating quantity) between the respective magnetic disks 200 and the respective magnetic heads 120 should be controlled so as to be uniform for obtaining accurate access of the magnetic head 120 to the magnetic disk 200. For this reason, the respective suspensions 133 are required to be fixed precisely to the carriage 132.

Hereafter, detailed explanation will be made on how to fix the suspension 133 to the carriage 132.

FIG. 3 is an exploded perspective view of the carriage 132 and the suspension 133.

As shown in FIG. 3, the carriage 132 is constituted by: the arm shaft 131; a trunk section 1321 extending from the arm shaft 131; and a stem section 1322 branching from the trunk section 1321. The ends of the stem section each have a joining section 134B that the suspension 133 is connected to and has a through hole 132a formed therein.

Meanwhile, the suspension 133 has a joining section 134A that is connected to the carriage 132 and has a through hole 133a formed therein. A ridge 135 is formed around the circumference of the through hole 133a.

In assembling the carriage 132 and the suspension 133, the magnetic head 120 is first adhered onto the front end of the respective suspensions 133, followed by insertion of the ridge 135 of the suspension 133 into the hole 132a of the carriage 132. According to the example shown in FIG. 3, the six suspensions 133 are fixed to the carriage 132 in the following manner: the first suspension is inserted so as to be disposed under the top level of the stem section 1322; the second two suspensions are inserted such that they sandwich the second level of the stem section 1322; the third two suspensions are inserted such that they sandwich the third level of the stem section 1322; and the last suspension is inserted so as to be disposed on the bottom level of the stem section 1322.

FIG. 4 is a side view of the suspension 133 and the carriage 132.

As shown in FIG. 4, the plural suspensions 133 are connected to the carriage 132 such that the magnetic heads 120 face one another. Further, the ridge 135 of the suspension 133 is formed such that the circumference of the ridge 135 and the through hole 132a of the carriage match. FIG. 4 shows the state where the suspension 133 is temporarily fixed to the carriage 132 by positioning the through hole 133a on the through hole 132a.

Subsequently, the suspension 133 and the carriage 132 are supported by an ultrasonic crimping apparatus 300 for crimping the through holes 133a onto 132a.

FIG. 5 is a schematic diagram of the ultrasonic crimping apparatus 500 of the embodiment.

The ultrasonic crimping apparatus 300 is constituted by: a supporting section 310 for supporting the carriage 132; a motor 320 for driving and rotating a pole screw 330; the screw 330 rotated by the motor 320; a transmission section 340 for changing rotation of the screw 330 to linear movement and transmitting the linear movement to an ultrasonic horn 350; the ultrasonic horn 350 to be vibrated by application of ultrasonic wave; a vibrator 360 for applying ultrasonic wave to the ultrasonic horn 350 in the longitudinal direction; an oscillator 370 for oscillating the vibrator 360; and a control section 380 for controlling a whole of the ultrasonic crimping apparatus 300. The supporting section 310 corresponds to an example of the supporting section of the invention, while the ultrasonic horn 350 corresponds to an example of the crimping member of the invention. In addition, the vibrator 360 corresponds to an example of the ultrasonic application section and the ultrasonic vibrator of the invention. Further, a combination of the motor 320, the screw 330 and the transmission section 340 corresponds to an example of the driving section of the invention, while the control section 380 corresponds to the crimping control section of the invention.

The ultrasonic horn 350 in a tapered bar shape, which is larger toward its rear end and smaller toward its front end, is attached so as to face the supporting section 310.

Now, explanation of FIG. 5 is temporarily stopped for describing vibration of the ultrasonic horn 350.

FIG. 6 is a graph showing amplitudes of the ultrasonic horn 350.

The abscissa in the graph shown in FIG. 6 is associated with a distance from the root of the ultrasonic horn 350, while the ordinate is associated with an amplitude of the ultrasonic horn 350. The amplitude in vibration direction (in the longitudinal direction of the ultrasonic horn 350) is plotted with white dots, while the radial amplitude is plotted with black dots.

As the ultrasonic horn 350 is gradually tapered, application of ultrasonic wave to the ultrasonic horn 350 in the longitudinal direction causes the ultrasonic horn 350 to contract and extend in vibration direction as well as displace in radial direction even though the displacement amount is approximately as small as one-tenth of the amount of the amplitude in the vibration direction. Further, sections of minimum displacement and sections of maximum displacement are formed alternatively in the ultrasonic horn 350 in the longitudinal direction (see FIG. 7).

FIG. 7 shows an analysis result of radial displacement in the ultrasonic horn 350.

Closely hatched portions indicate vibration with large radial amplitude. The darker the hatched portion is, the larger the radial amplitude is. In the longitudinal direction, there are formed in the ultrasonic horn 350 three side portions P1, P2 and P3 of maximum displacement in radial direction.

FIG. 8 illustrates a principle of crimping processing by using the ultrasonic horn 350.

As shown in FIG. 8A, insertion of the front end of the ultrasonic horn 350 into a through hole H and application of the ultrasonic wave to the ultrasonic horn 350 in the longitudinal direction causes the front end of the ultrasonic horn 350 to displace also in the radial direction, which pushes and enlarges the through hole H.

Subsequently, the ultrasonic horn 350 is further moved into the through hole H up to a position where the thickness of the through hole H and that of the ultrasonic horn 350 match. Then, the though hole H is further pushed and enlarged by radial displacement of an approximately middle portion of the ultrasonic horn 350.

Then, the ultrasonic horn 350 is further inserted into the though hole H up to the root portion thereof which is the largest portion of the ultrasonic horn 350, where the through hole H is further pushed and enlarged by radial displacement of the root portion.

In this way, the ultrasonic horn 350 gradually pushes and enlarges the though hole H in radial direction.

Now, description will continue referring back to FIG. 5.

In fixing the suspension 133 to the carriage 132, the carriage 132 to which the suspension 133 is temporarily fixed is first supported by the supporting section 310, and then the front end of the ultrasonic horn 350 is positioned in a position where the through holes 133a and 132a respectively of the suspension 133 and the carriage 132 face each other.

After positioning of the ultrasonic horn 350, the control section 380 gives instruction to drive the motor 320 and the oscillator 370.

Driving of the motor 320 and rotation of the screw 330 causes the ultrasonic horn 350 to be moved toward the suspension 133 and the carriage 132 by the transmission section 340, and then the front end of the ultrasonic horn 350 to be inserted into the though holes 132a and 133a.

Subsequently, the oscillator 370 oscillates the vibrator 360, which applies ultrasonic wave to the ultrasonic horn 350.

The application of ultrasonic wave to the ultrasonic horn 350 causes radial displacement of the front end of the ultrasonic horn 350, which pushes and enlarges the through holes 132a and 133a and causes the ridge 135 of the suspension 133 to be bent outward, so that the suspension 133 is fixed onto the carriage 132.

Subsequently, the ultrasonic horn 350 is further inserted into the through holes 132a and 133a up to a position where the thickness of the ultrasonic horn 350 and that of the enlarged through holes 132a, 133a match. Crimping is further secured by radial displacement of an approximately middle portion of the ultrasonic horn 350.

Further, the ultrasonic horn 350 is inserted into the through holes 132a, 133a up to the largest root portion of the ultrasonic horn 350, where fixing is strengthened by radial displacement in the largest root portion.

As described above, according to the embodiment, the though holes 132a and 133a respectively of the carriage 132 and the suspension 133 are pushed and enlarged by radial displacement of the ultrasonic horn 350, by gradually inserting the ultrasonic horn 350, from the smaller portion to the larger portion thereof, into the through holes 132a and 133a according to the enlarged thickness of the through holes 132a and 133a. Such gradual insertion of the ultrasonic horn 350 prevents deformation of the suspension in a thin plate, and thereby enables the uniform floating amount of the plural magnetic heads 120 from the respective magnetic disks 200.

Up to this point the description of the first embodiment has been given. Hereafter a description will be given of a second embodiment of the invention. The second embodiment is similar to the first embodiment except the shape of an ultrasonic horn. Thus, to avoid redundancy, only characteristic points of the second embodiment will be described below. In the following description, components having the same functions as those of the above-described components are denoted by the same reference characters.

As shown in FIG. 7, in the ultrasonic horn 350 according to the first embodiment, sections of minimum displacement is minimized and sections of maximum displacement are formed alternatively in the longitudinal direction. According to the second embodiment, crimping processing is performed in the sections of maximized displacement.

FIG. 9 is a schematic view illustrating a part of the front end of an ultrasonic horn 400.

In the ultrasonic horn 400 according to the second embodiment, uniform thickness areas 410, 420, and 430, whose thickness are respectively uniform over a certain length, are formed in the positions corresponding to P1, P2 and P3 side portions according to the first embodiment shown in FIG. 7. The uniform thickness areas 410, 420 and 430 correspond to an example of the uniform thickness area of the invention.

FIG. 10 illustrates crimping processing using the ultrasonic horn 400.

As shown in FIG. 10, the ultrasonic horn 400 is constituted by: a tapered portion 401 which is smaller toward the front end and larger toward the rear end; and a fixed thickness area 402 of the fixed thickness. The tapered portion 401 further has the uniform thickness areas 410, 420 and 430 formed therein.

As shown in FIG. 3, the ends of the stem section 1322 are branched from the carriage 132, and the respective ends of the stem section 1322 are mated with suspensions 133. Accordingly, the carriage 132 fixed to the suspensions 133 is supported by the supporting section 310 shown in FIG. 5, such that the plural through holes 132a formed in the ends of the stem section 1322 are aligned with the plural through holes 133a of the suspensions 133.

The plural through holes 132a, 133a of the carriage 132 and suspensions 133 are crimped first in the tapered portion 401, sequentially in the order of the uniform thickness areas 410,420 and 430. Lastly, in the fixed thickness area 402 at the root of the ultrasonic horn 400, the plural through holes 132a of the carriage 132 and the plural through holes 133a of the suspensions 133 are crimped simultaneously.

Provision of such uniform thickness areas 410, 420 and 430 in the ultrasonic horn 400 enables efficient and uniform crimping of the plural through holes 133a and 132a of the suspensions 133 and the carriage 132. Additionally, simultaneous and final crimping of the plural through holes 132a and 133a can suppress fluctuations in crimped status.

It should be noted that the above description is not limited to production of a carriage assembly (arm) of a magnetic disk apparatus, but also employed, for example, to production of an arm for a magneto-optical disk.