JPS6363995B2 - - Google Patents

Description

Detailed Description of the Invention (a) Technical Field of the Invention The present invention relates to a magnetic disk device, and more particularly to a magnetic disk device whose surface is coated with a multilayered or mixed layered lubricant film of at least two types of lubricants. The present invention relates to an apparatus configuration capable of always maintaining the thickness and lubricating properties of the lubricating film of a magnetic disk in a steady state.

(b) Background of the Technology In recent years, in magnetic disk devices, attempts have been made to increase the recording density by making the magnetic film of the magnetic disk thinner, lowering the flying height of the magnetic head, etc. In addition to the above-mentioned lower flying height of the magnetic head, the magnetic head is in contact with the surface of the magnetic disk when stopped, and as the rotational speed increases, the magnetic head is slightly floated, so-called CSS.
As the adoption of the Contact Start Stop (Contact Start Stop) method progresses, head crushing such as wear and damage on the magnetic head and magnetic disk surface is likely to occur due to contact sliding at the time of starting and stopping rotation. Generally, special surface treatments such as applying a lubricant or coating with a lubricant film are carried out.

(c) Prior art and problems By the way, as the recording density of magnetic disk devices increases, lowering the flying height of the magnetic head becomes more and more important, and the lubricating film applied to the surface of the magnetic disk is gradually becoming thinner. requires an extremely thin lubricating film of around 100 Å with excellent lubrication durability. On the other hand, magnetic disk drives are increasingly becoming sealed types in order to prevent head crashes caused by dust intrusion. However, in such a sealed magnetic disk device, the temperature inside the sealed device increases due to air friction (windage loss) caused by the high speed rotation of the magnetic disk.
Normally, the internal atmosphere is cooled by a self-circulating air cooling system, but depending on the usage conditions, a temperature rise of about 60 to 70 degrees Celsius is unavoidable, and this temperature rise may cause the surface of the magnetic disk to rise. There is a disadvantage that the lubricating film applied to the surface evaporates and disappears, deteriorating its lubricating properties, and there is a strong demand for a lubricating film with excellent heat resistance that can eliminate this disadvantage.

Incidentally, in response to these demands, common lubricants conventionally used to form a lubricant film on the surface of a magnetic disk include paraffin, higher alcohol, higher fatty acid, esterified product of higher fatty acid, etc. hydrocarbon-based lubricants, or their fluorides, such as fluorocarbon-based oils, silicone-based oils consisting of Si--Si bond groups, and molybdenum disulfide, tungsten disulfide, graphite, and graphite fluoride. There are solid lubricants consisting of these, and these are used singly or in combination. Among the above lubricants, hydrocarbon-based lubricants, especially the lubricating film formed by higher fatty acids and their esters, have excellent lubricating properties and are therefore effective in improving lubrication durability. On the other hand, 60~
It has the drawback of poor heat resistance, such as gradual evaporation and loss of lubricity in a high temperature atmosphere of 70°C. Furthermore, lubricating films formed from fluorocarbon oils, silicone oils, and the like have excellent heat resistance but poor lubricating properties. Furthermore, since solid lubricants such as molybdenum disulfide are in the form of fine powder, they are generally used in combination with liquid or semi-solid grease-like lubricants, but the particle size of the lubricants is on the order of microns. Therefore, it is difficult to make a thin film.

Therefore, it is not only extremely difficult to obtain an ultra-thin lubricant film with excellent lubrication durability and heat resistance for high recording density, but also magnetic disks coated with such a lubricant film cannot be used as sealed magnetic discs. When used in a disk device, head crash problems were inevitable, making it difficult to perform high-density recording or reproduction.

(d) Purpose of the Invention In view of the above-mentioned conventional situation, the present invention is based on the principle that a substance under evaporating conditions does not evaporate in an atmosphere of saturated vapor of the substance, and is based on the principle that a substance under evaporation conditions does not evaporate in an atmosphere of saturated vapor of the substance. To suppress evaporation and loss of a lubricant film on the surface of a magnetic disk during rotational driving, especially a lubricant film coated in multiple layers with at least two types of lubricants, or a lubricant film coated with a mixture of these lubricants. It is an object of the present invention to provide a novel magnetic disk device that can always maintain the lubricating film in a steady state with good lubrication properties.

(e) Structure of the Invention According to the present invention, this object is to provide a magnetic hub unit that is integrally supported by a hub mechanism portion whose surface is coated with a lubricating film in a multilayered or mixed layered form with at least two types of lubricants. In a magnetic disk device configuration in which a disk is hermetically sealed within an airtight storage lid, a lubricant that is most likely to evaporate due to temperature rise among at least two types of lubricants forming the lubricant film coated on the surface of the magnetic disk is placed in the airtight device. This is achieved by providing a magnetic disk device characterized by having an evaporation source made of a lubricant that is easy to lubricate.

(f) Embodiment of the Invention An embodiment of the present invention will be described in detail below with reference to the drawings.

The figure is a sectional view of a main part conceptually showing such an embodiment. In the figure, 1 has a first lubricating film made of behenic acid, which has lower lubricity than myristic acid, which is a type of higher fatty acid, and has a relatively high melting point, on the front and back surfaces, and myristic acid, which has excellent lubricity, on the top surface. A magnetic disk formed by coating a two-layered lubricant film (not shown) with a second lubricant film made of acid to a total thickness of about 100 Å, 2 is a magnetic disk in which a plurality of magnetic disks 1 are integrated. A hub mechanism section 3 is supported and attached to the rotating shaft 6 of the rotary drive mechanism 5, 3 is a center ventilation hole of the hub mechanism section 2, and 4 is in communication with the center ventilation hole 3 to circulate between each magnetic disk 1. A filter 7 is attached to the inner wall surface of the central ventilation hole 3 so as to cover each of the four ventilation holes. Further, reference numeral 8 denotes an airtight storage lid that seals the magnetic disk 1 on the base portion 11, and the inner wall surface 9 of the lid is processed to have an uneven surface or a porous surface, for example. Among the lubricants that make up the two-layered lubricant film coated on the surface of the magnetic disk, myristic acid, which evaporates most easily when the temperature rises (e.g. 60 to 70°C) and has excellent lubricity, An evaporation source lubricant film 10 is attached to the evaporation source lubricant film 10 on which a lubricant is deposited by vapor deposition or the like.

In this figure, in order to simplify the explanation, the magnetic head, head actuator, etc. whose configuration is not particularly different from the conventional one are omitted.

As described above, if the structure is such that the easily evaporable evaporation source lubricating film 10 is attached to the inner wall surface 9 of the airtight storage lid 8 in the magnetic disk device, air friction (windage loss) caused by the high speed rotation of the magnetic disk 1 can be applied. ) is circulated along the inner wall surface 9 of the airtight housing lid 8 as shown by the arrow in the figure, heating the evaporation source lubricating film 10 attached to the inner wall surface 9. lubricant vapor consisting of myristic acid is generated. The generated lubricant vapor flows from above and below into the central ventilation hole 3 of the hub mechanism section 2 along with the hot air flow, passes through a filter 7, and removes dust such as lubricant, large particles of lubricant vapor, etc. The clean lubricant vapor flows out between the magnetic disks 1 through the communicating small ventilation holes 4, and is repeatedly circulated within the airtight housing lid 8 so as to surround the magnetic disks 1. At this time, the temperature inside the airtight housing lid 8 is
The temperature is around 60-70℃.

The two-layer structure of the lubricant film on the surface of each rotating magnetic disk 1 is caused by the vapor pressure of the lubricant vapor mainly consisting of myristic acid, which selectively evaporates due to the temperature increase due to air friction during high-speed rotation. , the vapor pressure of the circulating lubricant vapor made of myristic acid surrounding the lubricant film on the surface of each magnetic disk 1 becomes approximately in equilibrium, and the evaporation of the lubricant film on the surface of each rotating magnetic disk 1 is prevented, and the It becomes possible to easily maintain a steady state with good lubrication properties. By the way, if there is no conventional evaporation source lubricating film, magnetic disk 1 can be removed by CSS operation after 200 hours.
Head crushes such as scratches occur on the surface of the
The coefficient of friction of the lubricant film was 0.45 or more, and the lubricant film was scattered and disappeared. However, when the magnetic disk 1 was rotated at high speed in a lubricant vapor atmosphere as described above, even if the CSS operation was repeated 100 times, No head crush such as scratches was observed on the surface of the magnetic disk 1, and the friction coefficient of the lubricant film on the surface of the magnetic disk 1 was 0.15 to 0.18, indicating that the lubrication characteristics from the beginning of high-speed rotation were maintained well without any change. It was confirmed that

In the above embodiment, the lubricant is coated not only on the front and back surfaces of the magnetic disk 1 in the airtight container 7 but also on other functional parts, but the lubricant film is extremely thin. It does not particularly impair the functionality of the device. Furthermore, in this embodiment, an example has been described in which an evaporation source for generating lubricant vapor is provided in the form of a lubricant film 10 on the inner wall surface 9 of the airtight housing lid 8, but the present invention is not limited to this. Instead, it may be placed at a suitable location within the sealing device, or may be placed with a heater if necessary. Furthermore, the evaporation source for generating lubricant vapor disposed in the sealing device is not limited to myristic acid as described in this embodiment, but for example, the lubricant film on the surface of the magnetic disk 1 to be
A two-layer lubricant film consisting of a first lubricant film made of cerotic acid and a second lubricant film made of stearic acid laminated on top of the first lubricant film, or a lubricant made of cerotic acid and a lubricant made of stearic acid in equivalent amounts. In the case of a mixed layered lubricant film mixed with stearic acid, it is sufficient to use a lubricant made of stearic acid, which is the most easily evaporated of the two lubricants and has excellent lubricity, and the same effect can be obtained. . Furthermore, easily evaporable higher aliphatic alcohols, higher fatty acid esters, fluorinated oils, etc. are also applicable.

(g) Effect of the invention As is clear from the above explanation, according to the structure of the magnetic disk device according to the present invention, even if the inside of the sealing device becomes high temperature, it can be coated with at least two types of lubricants. This has the excellent advantage that the evaporation and loss of the lubricant film on the surface of the magnetic disk can be easily suppressed, and the thickness and lubricating properties of the lubricant film can always be maintained in a good steady state. This type of magnetic disk device, especially the low flying height of the magnetic head, CSS
It is extremely advantageous to apply this method to a sealed magnetic disk device employing the above method.

[Brief explanation of drawings]

The drawing is a sectional view of a main part conceptually showing an embodiment of a magnetic disk device according to the present invention. In the drawings, 1 is a magnetic disk coated with a lubricant film made of at least two types of lubricants, 2 is a hub mechanism, 3 is a central ventilation hole, 4 is a small ventilation hole, 5 is a rotational drive mechanism, 6 is a rotating shaft, 7 is a filter, 8 is an airtight housing lid, 9 is an airtight housing lid 8
, 10 is an evaporation source lubricating film, and 11 is a base portion.

Claims (1)

[Claims] 1. In a magnetic disk device in which a magnetic disk whose surface is coated with a multi-layered or mixed-layer lubricant film of at least two types of lubricants is sealed in an airtight storage lid, the magnetic disk is 1. A magnetic disk device characterized in that an evaporation source of a lubricant that evaporates most easily due to temperature rise among at least two types of lubricants constituting a lubricant film coated on a disk surface is provided.