JP3359386B2 - Guide device for driving magnetic head - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a guide device in a linear direction, and more particularly to a guide device for a linear actuator for driving a head in an information recording / reproducing device such as a magnetic disk device, an optical disk device, a magneto-optical disk device and a floppy disk device. It is.

[0002]

2. Description of the Related Art Among information recording / reproducing apparatuses conventionally used, for example, a structure of a linear actuator for driving a magnetic head incorporated in a head disk assembly of a magnetic disk device is shown in FIG. To
A head arm 22 having a plurality of magnetic heads 21 attached to the movable portion 20;
And a carriage 23 provided with rolling elements 1 for performing movement
And a coil 24 forming a drive source, and a guide portion 25 has a guide rail 2 attached to a housing 26 for guiding the magnetic head 21 to the magnetic disk 30. When a magnetic force is generated in a magnetic circuit (not shown) formed behind the coil 24 of the movable portion 20 and the coil 24 is energized, a Lorentz force is generated between the coil 24 and the magnetic circuit. As a result, the movable section 20 is moved in the direction of the arrow, and the magnetic head 21 at the tip of the movable section 20 is guided to a predetermined track on the magnetic disk 30.

On the other hand, the guide device composed of the rolling element 1 and the guide rail 2 is made of a steel material such as high-carbon chromium bearing steel. However, the rolling property of the rolling element 1 is poor.
There was a problem that reproducibility when the movable portion 20 reciprocated on the guide rail 2 (the consistency between the trajectory of the center of the rolling element 1 and the return trajectory) was not obtained, and the wear was severe.

Therefore, in recent years, the linear actuator 10
The importance of the guide accuracy has been emphasized, and a guide device using ceramics such as alumina, zirconia, or silicon nitride for one of the guide devices has been proposed. (JP-A-59-129633, JP-A-60-2202)
The guide device having such a structure is used not only for the information recording / reproducing device but also for various processing devices and molding devices. For example, a compression molding of metal or ceramic powder is performed. Alternatively, a guide device including a transfer rail and a rolling element that rotates on the transfer rail is used in a hot isostatic pressing device for compression firing. Further, a bogie having rollers on a processing board is provided in devices in various fields, such as a guide device that moves on a guide rail and guides a workpiece to a next processing step.

[0005]

However, in the guide device shown in FIG. 1, of the rolling elements 1 and the guide rails 2,
On the other hand, even with a guide device using ceramics, it has been difficult to improve rolling properties and reduce wear due to friction.

That is, since there is no lubricant or a material having a lubricating action interposed between the contact surfaces of the rolling elements 1 and the guide rails 2, even if the surface of the guide rails 2 is formed smoothly. However, it was difficult to reduce wear and improve the rolling properties.

For example, in a guide device having a guide rail 2 made of alumina ceramic, even if the guide surface 2a of the guide rail 2 is mirror-finished, there are irregularities on the guide surface 2a and a high carbon chromium bearing steel When the rolling element 1 is rotated on the guide rail 2, the hardness of the high carbon chromium bearing steel is inferior to that of the alumina ceramic.
The outer peripheral surface 1a of the rolling element 1 is roughened by the convex portion of the guide surface 2a,
There was a problem of wearing.

When a guide device in which the guide rails 2 are formed of silicon nitride is used, adhesion occurs between the contact surfaces of the rolling elements 1 and the guide rails 2 to increase the coefficient of friction and impair the rolling performance. At the same time, there is a problem that both the outer peripheral surface 1a of the rolling element 1 and the guide surface 2a of the guide rail 2 are worn.

On the other hand, in the guide device in which the guide rail 2 is formed of zirconia ceramics, the outer peripheral surface 1a of the rolling element 1 is not only worn out but also in the same manner as the guide device formed of alumina ceramics. Due to the increase in frictional heat accompanying the high speed, a considerable temperature is reached at the contact surface between the outer peripheral surface 1a of the rolling element 1 and the guide surface 2a of the guide rail 2, so that a phase transformation occurs in the zirconia ceramics forming the guide rail 2. In addition, there is a possibility that a crack may occur on the guide surface 2a.

Further, if the abrasion powder generated by the abrasion adheres to the outer peripheral surface 1a of the rolling element 1 and the guide surface 2a of the guide rail 2, not only the stable guidance of the movable section 20 is not possible, but also the reproducibility of the movable section 20 is improved. If information is recorded or reproduced while the wear powder is damaged and adheres to the magnetic disk 30, the wear powder is caught in the gap between the magnetic head 21 and the magnetic disk 30, and the magnetic head 21 or the magnetic disk 30 There was a danger of scratching.

Thus, today's information recording / reproducing devices include:
As the frequency of movement of the movable section 20 has increased, higher durability has been required, but no guide device has satisfied such performance.

[0012]

SUMMARY OF THE INVENTION In view of the above-mentioned problems, the present invention has been made in consideration of the above-mentioned problems, and in a guide device for driving a magnetic head comprising a guide rail and a rolling element, a rolling element is made of high carbon chromium bearing steel, cast iron, or structural steel. The guide rail is made of a steel material such as, for example, having a hardness of 19 GPa or more, a bending strength of 350 MPa or more, a coefficient of thermal expansion in the range of 7.5 to 8.1 × 10 ^-6 / ° C., and titanium carbide, titanium carbide and titanium nitride. Or a sintered body containing one of titanium carbide and alumina as a main component, and the surfaces of the rolling elements and the guide rails that abut each other have a center line average roughness (Ra) of 0.0
The thickness is set to 5 μm or less.

[0013]

According to the present invention, one of the guide rail and the rolling element, which constitute the guide device of the linear actuator for driving the head, is formed of the above-mentioned sintered body. Compatibility can be improved.

Therefore, in the guide device of the present invention, the amount of wear of both the rolling element and the guide rail can be significantly reduced, and the rolling performance can be improved. Moreover, since the amount of deflection of the guide rail can be reduced, the reproducibility of the movable portion of the linear actuator can be further improved.

[0015]

Embodiments of the present invention will be described below. However, the same parts as those of the conventional example are denoted by the same reference numerals.

FIG. 1 is a diagram showing a linear actuator for driving a magnetic head provided with a guide device according to the present invention. The linear actuator 10 comprises a movable section 20 and a guide section 25. The movable section 20 includes a plate arm 22a having magnetic heads 21, 21 mounted on a plate 22a arranged at equal intervals, a carriage 23 having a rolling element 1 for moving the movable section 20, and a driving source. The guide portion 25 has a structure in which the guide rail 2 is attached to the inner wall surface of the housing 26 in order to guide the movable portion 20 to move.

The linear actuator 10 includes a coil 2
4 A magnetic force is generated by a magnetic circuit (not shown) arranged at the rear, and a voltage is applied to the coil 24 to generate a Lorentz force. The Lorentz force moves the movable section 20 to move the magnetic head 21 to the magnetic head. It is designed to guide to a predetermined track on the disk 30.
As shown in FIG. 2, the guide device including the rolling elements 1 and the guide rails 2 includes two ball bearings attached to the guide rail 2 having a pentagonal cross section in a C-shape. The structure is such that the moving body 1 is pressed.

The rolling element 1 is not limited to a ball bearing, but may be a roller. Even in the mounting structure of the rolling element 1, the rolling element 1 arranged in parallel with a bogie is moved by an object that guides movement. A guide device having guide rails 2 arranged in parallel along the arrangement of the guide rails 2 may be used. However, a linear actuator 10 such as an information recording / reproducing device
When high movement accuracy is required for the
It is desirable to adopt the structure shown in FIG. Also, the cross-sectional shape of the guide rail 2 may be a shape having a polygonal shape or a round shape depending on the mounting structure of the rolling element 1.

On the other hand, in the above guide device, the rolling element 1 is formed of a steel material such as high carbon chromium bearing steel, cast iron, or structural steel, and the guide rail 2 is made of titanium carbide, titanium carbide and titanium nitride, or titanium carbide and alumina. Of these, it is formed of a sintered body mainly composed of one kind. Therefore, guide rail 2
Since the amount of flexure is small even when the weight of the movable part 20 is added to the linear actuator, the linear actuator 10 including the guide device constituted by this combination can obtain excellent reproducibility of the movable part 20, No off-track of the head 21 occurs.

Further, since the rolling element 1 is formed of a steel material, the rolling element 1 can be easily processed. Since the steel materials having different hardnesses are rotated and moved on the sintered body, the rolling property can be improved.

When the rolling element 1 is a ball bearing,
If the ball 1b interposed between the outer ring 1c and the inner ring 1d is formed of the above-mentioned sintered body, the outer ring 1c can be rotated more smoothly.

The sintered body is made of titanium carbide (TiC) or a sintered body containing titanium carbide (TiC) and titanium nitride (TiN) as main components. It is contained in the range of 80 to 100% by weight of the whole. Further, 10% by weight of the total
Or less, preferably 7.5 wt% or less of Ni, C
It is desirable to contain metal components such as o and Mo. These metal components serve as sintering aids. However, if the content of the metal components is more than 10% by weight, the rolling elements 1 made of steel material are likely to adhere to each other. Of 1
The range is 0% by weight or less, preferably 7.5% by weight or less.

In addition to the above components, molybdenum carbide (M
o ₂ C), chromium carbide (Cr ₃ C ₂ ), and tungsten carbide (WC),
It can be contained in the range of not more than% by weight, and by including these components, sinterability can be improved and toughness and strength can be further improved.

As described above, since the sintered body containing the above components in a predetermined amount has a hardness of 19 GPa or more, a bending strength of 350 MPa or more, and has high toughness, the amount of deflection with respect to the weight of the movable part 20 is reduced. However, wear of the guide surface 2a can be reduced. In addition, the titanium carbide contained in the sintered body has a lubricating action and is very compatible with steel.
Therefore, the wear of the outer peripheral surface 1a of the rolling element 1 moving on the guide rail 2 can be reduced, so that it is optimal as a material for forming the guide rail 2.

Also, since the sintered body mainly containing titanium carbide and titanium nitride contains titanium nitride,
Excellent corrosion resistance. Therefore, a highly reliable guide device can be provided such that it does not corrode even in a humid environment.

Next, another embodiment of the sintered body according to the present invention will be described.

Other sintered bodies used in the guide device of the present invention include titanium carbide (TiC) and alumina (Al ₂ O ₃ ).
The alumina content in this case is in the range of 70 to 10% by weight of the whole, and the content of titanium carbide is 20 to 80% by weight of the whole.
Range.

Here, the content of titanium carbide is 20% by weight.
The reason for this is that if the content is less than 20% by weight, the effect of the lubricating action is low, so that smooth rolling properties cannot be obtained. And, as the content of titanium carbide increases, the lubricating action increases, so that the contact state with the steel material can be further improved, smooth rolling properties can be obtained, and the rolling element 1 and the guide rail due to friction can be obtained. 2 can also reduce the amount of wear. Moreover, by increasing the content of titanium carbide, the hardness, strength, and toughness of the sintered body can be further improved, and the sintered body becomes optimal as a material for forming the guide rail 2.

As the sintering aid for binding the above main components, zirconia (ZrO ₂ ), molybdenum oxide (Mo)
Components such as ₂ O ₃ ) and magnesia (MgO) must be contained in the range of 2 to 10% by weight of the whole. This is because if the content of the sintering aid is less than 2% by weight, it is difficult to sinter the alumina particles and the titanium carbide particles, which are the main components, and if the content is more than 10% by weight, characteristic deterioration occurs. This is because there is fear.

In order to produce the above sintered body, the above-mentioned raw materials are prepared and pulverized to prepare a secondary raw material, and the secondary raw material is formed by a method such as mechanical pressing or extrusion molding. By firing at a temperature of ° C., a sintered body can be obtained. Note that hot isostatic pressing (HIP) may be performed to further increase the density and increase the strength. Then, the obtained sintered body is subjected to cutting,
Guide rail 2 of specified dimensions as a cylinder or prism
The desired guide rail 2 can be manufactured by polishing the surface on which the rolling element 1 rotates as a final finish.

At this time, the surface roughness of the guide surface 2a of the guide rail 2 needs to be 0.05 μm or less in center line average roughness (Ra), and the guide rail 2 having a surface roughness in this range is required. When the rolling element 1 made of steel material is rotationally moved above,
Outer peripheral surface 1a of rolling element 1 and guide surface 2a of guide rail 2
, The rolling element 1 can be smoothly rolled, and the movable portion 20 can be stably guided.

However, the surface roughness of the outer peripheral surface 1a of the rolling element 1 made of a steel material in contact with the guide rail 2 is desirably 0.05 μm or less in terms of center line average roughness (Ra).

The sintered body of the present invention obtained in this way has a hardness of 19 GPa or more and a bending strength of 35 GPa.
Since it is a sintered body having excellent wear resistance and strength of 0 MPa or more, having high toughness and having a self-lubricating action,
When the rolling element 1 made of steel is rotationally moved on the guide rail 2 formed of the sintered body, the wear of the guide surface 2a can be reduced, and the wear of the steel material as the mating material can be reduced. . Further, since the amount of deflection of the guide rail 2 with respect to the weight of the movable portion 20 can be reduced, the movable portion 2
The smooth movement of 0 and the reproducibility can be improved, and the life is long.

The coefficient of thermal expansion of the sintered body of the embodiment of the present invention is about 7.5 to 8.1 × 10 ^-6 / ° C., but within this range, the guide rail 2 expands due to frictional heat. Even so, there is no problem in the positioning reproducibility of the movable section 20.

(Experimental Example) Here, a ball-on-disk type friction and wear tester was used to examine the wear resistance and slidability of the combination of the sintered body and the steel material constituting the guide device of the present invention. Tests were performed using

Examples of the present invention include a sintered body containing titanium carbide and titanium nitride as main components, a sintered body containing titanium carbide as a main component as a dispersed particle phase, and chromium carbide and nickel as a binder phase; And a plate-shaped body made of a sintered body containing alumina and titanium carbide as main components is prepared. As comparative examples, alumina ceramics, silicon nitride ceramics,
A plate made of zirconia ceramics was used, and a ball made of high carbon chromium bearing steel SUJ2 was prepared as a mating material of each sample.

However, the contents of the components forming the sintered body according to the embodiment of the present invention and the surface roughness of the plate-like body are as shown in Table 1.

Then, in a dry state without lubrication, a ball made of high carbon chromium bearing steel SUJ2 was brought into contact with the surface of the plate-like body of each sample by applying a load of 0.5 kg, and the relative sliding speed was set to 0. The experiment was performed by rotating the plate-like body of each sample so as to be 17 m / s, and the friction coefficient between the two and the wear amount thereof were measured.

Table 1 shows the results.

[0040]

[Table 1]

As can be seen from Table 1, in the comparative examples of Nos. 4 to 6, the coefficient of friction was as large as 0.45 or more.
Except for the comparative example, the amount of wear was large. In contrast, in Examples Nos. 1 to 3 of the present invention, the coefficient of friction was 0.45.
Since it can be kept lower and the amount of wear can be reduced, it can be seen that it is excellent in wear resistance and slidability. Further, in the embodiment of the present invention, the wear amount of the mating member can be reduced, so that the life can be extremely extended.

(Experimental Example 2) Next, the sintered bodies (No.
Using 3), the surface roughness of the guide surface is set to 0.
Guide rails finished to 01, 0.02, 0.05, and 0.07 μm were prepared, and the wear amount of the ball bearing when the ball bearing made of high carbon chromium bearing steel was rotated was measured. The outer peripheral surface of the ball bearing is finished to have a center line average roughness of 0.05 μm.

As a result, the wear amount can be reduced as the center line average roughness of the guide surface is reduced, and when the center line average roughness is set to 0.01 μm, the wear amount of the ball bearing is reduced most. I was able to. Also, it was found that the wear amount of the ball bearing can be reduced if the surface roughness of the guide surface is at least 0.05 μm in center line average roughness. The same result was obtained not only for the sintered body of No. 3 but also for all of the sintered bodies of the examples of the present invention.

In the above embodiments, the guide device for the linear actuator for driving the head incorporated in the information recording / reproducing apparatus is described. However, the present invention is not limited to these structures and applications. It is needless to say that it is composed of the rolling elements 1 and the guide rails 2 and can be applied to a guide device arranged in an industrially used device such as various processing devices and forming devices.

[0045]

According to the present invention, of the guide device for driving a magnetic head comprising a guide rail and a rolling element, the rolling element is formed of a steel material such as high carbon chromium bearing steel, cast iron, or structural steel. With a hardness of 19 GPa or more, a bending strength of 350 MPa or more, and a thermal expansion coefficient of 7.5 to 8.1 ×.
It is in the range of 10 ⁻⁶ / ° C., and is formed of a sintered body containing titanium carbide, titanium carbide and titanium nitride, or titanium carbide and alumina as a main component, and the rolling element and the guide rail are in contact with each other. By setting the surface to have a center line average roughness (Ra) of 0.05 μm or less, it is possible to obtain a smooth rolling property of the rolling element made of a steel material, and it is possible to greatly reduce the wear amount of both members. Therefore, it is possible to provide a long-life magnetic head driving guide device. Moreover, since the amount of deflection of the guide rail can be reduced, excellent reproducibility of the rolling elements can be obtained. Therefore, the linear actuator provided with the guide device of the present invention can realize a high-speed moving body and can maintain high accuracy even when the frequency of use is increased. This can contribute to higher processing speed and higher information recording density.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a linear actuator including a guide device of the present invention.

FIG. 2 is a partially enlarged sectional view showing an operation state of the guide device according to the present invention.

[Description of Signs] 1 ... rolling element 1a ... outer peripheral surface 2 ... guide rail 2a ... guide surface 10 ... linear actuator 20 ... movable part 21 ... magnetic head 22 ... head arm 23 ... carriage 24 ... coil 25 ... guide part 26 ... housing

Claims (1)

(57) [Claims] 1. A guide rail with a magnetic head drive guide apparatus comprising a rolling element for rotational movement on the guide rails, the rolling elements are formed of steel, the guide rail
A hardness of 19 GPa or more, a bending strength of 350 MPa or more,
And forming a sintered body having a thermal expansion coefficient contains <br/> titanium carbide in the range of 7.5~8.1 × 10 ^-6 / ℃,
Centering on the contact surfaces of the rolling elements and guide rails
In particular, the line average roughness (Ra) is set to 0.05 μm or less.
A guide device for driving a magnetic head .