JPH08309664A - Manufacture of diamond grinding wheel and magnetic head - Google Patents

Abstract

PURPOSE: To provide a method for manufacturing a diamond grinding wheel and a magnetic head whereby generation of cracking and chipping is reduced to improve a yield rate. CONSTITUTION: The first diamond abrasive grain 20 of 20μm to 30μm grain size and the second diamond abrasive grain 21 to 5μm to 10μm grain size are mixed by ratio of 15 to 25wt.% the second diamond abrasive grain 21 relating to the first diamond abrasive gain 20, to bind the abrasive grains by a binding agent 22.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a diamond grindstone for processing a magnetic head or the like used in a magnetic recording / reproducing apparatus and a method for manufacturing the magnetic head.

[0002]

2. Description of the Related Art In recent years, with the downsizing of magnetic recording devices and the increasing density of magnetic recording, precision machining has been performed on magnetic heads.

Hereinafter, a conventional magnetic head will be described first, and then a conventional magnetic head manufacturing method and a diamond grindstone will be described with reference to the drawings. FIG. 3 is a perspective view of a conventional magnetic head. In FIG. 3, 1 is a slider made of ceramics, 2 is a coil bobbin wound, 3 is a back bar, and 4 is a head structure composed of a recording / reproducing head and an erasing head. The head structure 4, which is the main part of such a magnetic head, is made of ferrite and glass as described later.

Next, a method of manufacturing the magnetic head will be described. 4A to 4C are views showing the processing of the gap bar of the head structure in the conventional magnetic head manufacturing method, and FIGS. 5A and 5B are head structure in the conventional magnetic head manufacturing method. 6A and 6B are views showing the joining and processing of the gap bar, and FIGS. 6A and 6B are views showing the cutting and lapping of the head structure in the conventional magnetic head manufacturing method.

First, in FIG. 4 (a), 5 is a core bar made of ferrite, the groove 6 is ground with a diamond grindstone, and the gap facing surface 7 is ground with diamond abrasive grains. 8 is made of ferrite I
This is a V-shaped core, and one surface of the I-shaped core 8 is polished. Then, S having a high softening point temperature is formed by sputtering.
A film 9 of iO ₂ is formed on the gap facing surface 7 of the core bar 5 and the polished surface of the I-shaped core 8, respectively. Further, a low melting glass film 10 is formed on each film 9 of the core bar 5 and the I-shaped core 8. Then, the glass film 10 of the core bar 5 and the glass film 10 of the I-shaped core 8 are butted against each other to form a magnetic gap.

Next, in FIG. 4B, reference numeral 11 is a gap bar having a magnetic gap, and a track regulating groove 12 is formed by grinding with a diamond grindstone in order to form a track width of the magnetic head on the upper surface. Then, the plurality of track regulating grooves 12 having the track width of the gap bar 11 are filled with mold glass.

Next, in FIG. 4 (c), 13 is a cup-shaped diamond grindstone, and the portion of the gap bar 11 filled with the mold glass and the lower portion are ground to respective dimensions.

Next, in FIG. 5A, 14 is a recording / reproducing gap bar, 15 is an erasing gap bar, and the gap bar 15 is a recording / reproducing gap bar 14.
It is formed by a process similar to. Then, after grinding the surfaces of the gap bars 14 and 15 on the opposite sides of the magnetic gaps of the I-shaped core 8, the diamond bars of resinoid bond are used for polishing. Then, the polished I-shaped cores 8 are back-to-back and bonded with an adhesive.

Next, in FIG. 5B, 16 is a magnetic head bar, and in FIG. 5A, the gap bars 14 and 15 are shown.
After joining, the depth of the magnetic gap and the back side were ground and polished using a diamond grindstone or the like, respectively.

Next, in FIG. 6A, 17 is a diamond grindstone for cutting the magnetic head bar 16, and 18 is a magnetic head chip cut by the diamond grindstone 17.

Next, in FIG. 6B, reference numeral 19 is a cut surface of the magnetic head chip 18. Magnetic head chip 18
A fine diamond abrasive grain is interposed between the cutting surface 19 of and the rotating surface plate, and the head structure 4 is formed by lapping. Then, the head structure 4 forms a magnetic head as shown in FIG. 3 through a washing process, a bonding process to the slider 1, a lapping process of a sliding surface, and an assembling process of the back bar 3.

Next, the conventional diamond grindstone 17 will be described. 6A for cutting the magnetic head bar 16 has a diameter of 52 mm and a thickness of 0.21 mm, the conventional diamond grindstone 17 has a size of 52 mm and a thickness of 0.21 mm. The resin is bonded with a binder made of resinoid bond material. The diamond grindstone 17 has a diamond abrasive grain size of 20 μm to
30 μm, Concentration of diamond abrasive grains (JIS B 4131) is 125, that is, 1100 mg
The diamond abrasive grains having a ratio of / cm ³ are bonded with a binder.

[0013]

As described above, in the conventional diamond grindstone and magnetic head manufacturing method, in each of the processing steps for forming the head structure 4, grinding,
Machining with a diamond grindstone is performed for processing such as polishing and cutting. However, the diamond grindstone 17
Since the diamond abrasive grains that compose the above are formed with single abrasive grains of 20 μm to 30 μm, repeated use of the diamond grindstone 17 causes a phenomenon of clogging due to wear of the diamond abrasive grains and grinding debris attached to the diamond grindstone 17 to cause clogging. The phenomenon occurs frequently. When this crushing phenomenon or clogging phenomenon occurs, the workability of the work deteriorates and the cutting resistance increases, causing heat to be generated, and the generated heat is locally stored in the work, and due to thermal expansion, etc. It causes cracks such as small cracks and chipping of minute chips. If cracks or chippings are present near the sliding surface of the magnetic head on which the magnetic recording medium slides,
There is a problem in that the yield is lowered because the magnetic recording medium is damaged during sliding and the reliability is deteriorated.

The present invention solves the above problems.
An object of the present invention is to provide a diamond grindstone and a method for manufacturing a magnetic head, in which the occurrence of cracks and chippings is reduced and the yield is improved.

[0015]

To achieve this object, the diamond grindstone of the present invention has a particle size of 20 μm to 30 μm.
The first diamond abrasive grain of μm and the grain size of 5 μm to 10
It is characterized in that the second diamond abrasive grains having a diameter of μm are mixed with the first diamond abrasive grains at a ratio of 15 to 25% by weight and are bonded by a binder.

The magnetic head manufacturing method of the present invention is to process a magnetic head chip using a diamond grindstone.

[0017]

Function: The diamond grindstone of the present invention has a particle size of 20 μm.
First diamond abrasive grains of ~ 30 μm and grain size of 5 μm
Since the second diamond abrasive grains having a size of 10 μm are mixed, heat is easily dissipated and chips are easily released, and the phenomenon of crushing and clogging is reduced, and stable grinding and polishing capabilities can be provided.

Further, in the method of manufacturing a magnetic head of the present invention, the machined surface such as cutting, grinding and polishing is uniformly performed,
The quality can be easily maintained.

[0019]

An embodiment of the present invention will be described below with reference to the drawings. 1 (a) is a front view of a diamond grindstone according to an embodiment of the present invention, FIG. 1 (b) is an enlarged partial sectional view of a diamond grindstone according to an embodiment of the present invention, FIG. 2 (a) and FIG. 2 ( FIG. 6B is a schematic view for explaining a state of the diamond grindstone according to the embodiment of the present invention when the diamond grindstone is in use. Note that, in one embodiment of the present invention, the same reference numerals as those in the conventional example are basically the same, and thus detailed description thereof will be omitted.

1 (a), 1 (b) and 2 (a),
In FIG. 2B, 17 is a diamond grindstone of this embodiment. The diamond grindstone 17 of this embodiment is used when the magnetic head bar 16 is cut, and the diamond grindstone 17 is composed of an abrasive grain layer having a diameter of 52 mm and a thickness of 0.21 mm, and the grain size of the abrasive grain layer is 20 μm to 20 μm. 30 μm of first diamond abrasive grains 20 and particle size of 5 μm to 10 μm
The second diamond abrasive grain 21 of the former to the latter one
It is mixed at a ratio of 5 to 25% by weight, and the both are bound by a binder 22 such as a resinoid bond material made of resin or the like. The first diamond abrasive grain 20 and the second diamond abrasive grain 21 have a concentration of 125, that is,
It is bound at 1100 mg / cm ³ . And the binder 22
Holes 23 are formed inside.

The grain size of the first diamond abrasive grain 20 is set to 20.
The reason why μm to 30 μm is set is that the sharpness and the roughness of the cutting surface are appropriate when the particle size of the first diamond abrasive grain 20, which is the main force for cutting, is this size. If the abrasive grains are larger than 30 μm, the grinding ability is increased, but the surface roughness becomes rough, which causes cracks and chipping. When the abrasive grains are 20 μm or less, the reverse occurs, and the grinding ability is reduced.

The process of wear of the diamond grindstone 17 will be described. If the cutting of the magnetic head bar 16 is continued from the cross-sectional state of the diamond grindstone 17 shown in FIG. 1B, the tip of the first diamond abrasive grain 20 that comes into contact with the magnetic head bar 16 is first worn and the cutting is further continued. As shown in FIG. 2A, the tip of the second diamond abrasive grain 21 serves as a blade to contact the magnetic head bar 16 to start cutting. Then, this second diamond abrasive grain 21
The tip of the diamond also continues to wear together with the first diamond abrasive grains 20.

Next, how the second diamond abrasive grains 21 fall off will be described with reference to FIG. As shown in FIG. 2 (b), the second diamond abrasive grains 21 will be in the first state when the cutting is continued.
Since the surface area that is bonded to the binder 22 is smaller than that of the diamond abrasive grain 20, the bonding force is weak and the diamond abrasive grains fall off relatively early. That is, the first diamond abrasive grain 20 is a binder 22.
Since the surface area of the second diamond abrasive grain 21 is large enough to withstand the cutting resistance because it has a large surface area bound to the binder 2
The cutting force becomes larger than the bonding force of 2, and the second diamond abrasive grains 21 fall off.

If the second diamond abrasive grains 21 fall off before the first diamond abrasive grains 20,
The place where the second diamond abrasive grain 21 has fallen off is the hole 2
Therefore, the holes 23 facilitate the escape of heat and chips generated between the diamond grindstone 17 and the magnetic head bar 16. Then, the holes 23 cause the first diamond abrasive grain 20 or the second diamond abrasive grain 21 to newly form a blade. This is repeated in sequence, and diamond whetstone 1
7 can have stable grinding and polishing ability. The excellent heat dissipation can prevent cracking and chipping.

Thus, the diamond grindstone 1 of the present invention
No. 7 is the first diamond abrasive grain 20 having a grain size of 20 μm to
30 μm, the diameter of the second diamond abrasive grain 21 is 5 μm
-10 μm, second for the first diamond abrasive 20
The cracks and chipping are prevented by mixing the diamond abrasive grains 21 of No. 1 in the proportion of 15 to 25% by weight. Next, what will happen if this condition is not satisfied will be explained.

First, the case where the grain size of the second diamond abrasive grain 21 is smaller than 5 μm will be described. First diamond abrasive grain 20 and second diamond abrasive grain 2 during cutting
No. 1 wears while grinding and polishing together. Then, when a cutting resistance larger than the bonding force of the binder 22 is generated in the second diamond abrasive grain 21, the second diamond abrasive grain 21 falls off. By the way, the second diamond abrasive grain 2
Since the grain size of No. 1 is smaller than 5 μm, the shape of the pores 23 generated by the dropping of the second diamond abrasive grains 21 becomes small. Therefore, in the hole 23, the diamond grindstone 17
The function of radiating heat generated between the magnetic head bar 16 and the magnetic head bar 16 and releasing chips is reduced. Therefore, the grinding and polishing ability of the diamond grindstone 17 is reduced. Then, heat generated between the diamond grindstone 17 and the magnetic head bar 16 is accumulated, and the accumulated heat causes a crack when the magnetic head chip 18 is cut. Cracks and chipping occur.

Next, the case where the grain size of the second diamond abrasive grain 21 becomes larger than 10 μm will be described. Considering the frequency with which the second diamond abrasive grains 21 fall during cutting, the particle diameter of the second diamond abrasive grains 21 is 5 μm.
It is smaller than 10 μm. This is because the surface area of the second diamond abrasive grains 21 is large and the bonding force of the binder 22 is also large, and the second diamond abrasive grains 21 do not easily fall off even if cutting resistance occurs. Therefore, if the cutting of the magnetic head bar 16 is continued with the cutting resistance increased, the diamond grindstone 17 and the magnetic head bar 1
The heat generated between the magnetic head chip 16 and the magnetic head 6 accumulates in the magnetic head bar 16, and the accumulated heat causes a crack in the magnetic head chip 18 at the time of cutting, causing cracks and chipping on the cut surface of the magnetic head chip 18. Let them do it.

Next, the case where 25 wt% or more of the second diamond abrasive grains 21 are mixed in the first diamond abrasive grains 20 will be described. Both the first diamond abrasive grains 20 and the second diamond abrasive grains 21 during cutting are worn while grinding and polishing. However, since the second diamond abrasive grains 21 having a smaller grain size than the first diamond abrasive grains 20 are many, the cutting surface has a fine texture, but the grinding and polishing ability itself of the diamond grindstone 17 is low. Then, if the diamond grindstone 17 having low grinding and polishing ability is continuously cut, the diamond grindstone 17 is blunted,
The heat generated between the diamond grindstone 17 and the magnetic head bar 16 is accumulated in the magnetic head bar 16, and the accumulated heat causes a crack in the magnetic head chip 18. Cracks and chipping also gradually occur on the cut surface.

Next, a description will be given of what happens when the second diamond abrasive grains 21 are mixed in the first diamond abrasive grains 20 in an amount of less than 15% by weight. During the cutting, the tips of the first diamond abrasive grains 20 and the second diamond abrasive grains 21 wear while grinding and polishing. Then, when a cutting resistance larger than the binding force of the binder 22 of the second diamond abrasive grains 21 is generated, the second diamond abrasive grains 21 fall off but the second diamond abrasive grains 21 mixed are small, The number of voids 23 generated when the second diamond abrasive grains 21 fall off is reduced. Then, a crushing phenomenon or a clogging phenomenon in which chips are attached to the diamond grindstone 17 is likely to occur. The cutting resistance applied to the magnetic head bar 16 increases,
Frictional heat is generated between the diamond grindstone 17 and the magnetic head bar 16, and this frictional heat causes a crack in the magnetic head chip 18 at the time of cutting, causing cracks and chipping on the cut surface of the magnetic head chip 18. It causes it.

For the above reasons, the diamond grindstone 17 of the present invention comprises the first diamond abrasive grain 20 having an abrasive grain of 20 μm to 30 μm and the second diamond abrasive grain 21 having an abrasive grain of 5 μm to 10 μm. It is necessary to mix the diamond abrasive grains 20 at a ratio of 15 to 25% by weight and bond them with the binder 22. As a result, the phenomenon of crushing and clogging is reduced, and cracks and chipping are reduced in processing such as grinding, polishing, and cutting.

Next, a method of manufacturing the magnetic head of the present invention will be described. The processing of the head structure of the magnetic head is similar to that shown in FIGS. 4A to 4C, 5A and 5B, and 6A and 6B of the conventional example, This is different from the conventional example in that the diamond grindstone 17 of the present invention is used for processing in at least one of the steps. In the processing of the groove 6 of FIG. 4A, the groove 6 to be ground is wide, so that the diamond grindstone has a first diamond abrasive grain 20 and a second diamond abrasive grain 21 of the present invention which are metallized with a resinoid bond material. Used in combination with. Processing of the track regulating groove 12 of FIG. 4B and magnetic head bar 16 of FIG. 6A
To cut the magnetic head chip 18, the diamond grindstone 17 having a diameter of 52 mm and a thickness of 0.21 mm in this embodiment is used.
To use.

Further, the cup type diamond grindstone of the present invention is used for the grinding process of FIGS. 4 (c) and 5 (b).
However, since the cutting force is prioritized in any of the processes, a single abrasive grain diamond grindstone having an excellent cutting force may be used in this step in some cases. The cup-shaped diamond grindstone of the present invention is used for the polishing process of FIG. At this time, it is preferable to increase the ratio of the second diamond abrasive grains 21 within a predetermined ratio. Further, in the polishing process of FIG. 6B, the fineness of the surface is prioritized.
Lapping is performed by interposing fine diamond abrasive grains between 9 and the surface plate.

Next, the magnetic head bar 16 shown in FIG. 6A will be described in detail by taking an example of cutting it into the magnetic head chips 18. The diamond grindstone 17 of this embodiment used when cutting the magnetic head bar 16 has a spindle rotation speed of 30,000 rpm and a feed speed of 1.0 mm / min.
Under the condition of seconds, the magnetic head bar 16 having a height of 2 mm is repeatedly cut at a cutting pitch of 0.62 mm to form a plurality of magnetic head chips 18.

The diamond grindstone of the conventional example and the diamond grindstone 17 of the present invention were used for cutting under the same conditions, and the difference in the occurrence of cracks and chippings was examined. The evaluation of cracks and chippings is made by observing from the front and both side surfaces of the magnetic head chip 18 at a magnification of 200 times using an optical microscope, counting all the cracks that have occurred, and chipping is a side wrap in a post process. The generation rate was examined by counting those having a major axis of 30 μm or more that cannot be removed by processing or the like.

The crack and chipping occurrence rates examined in this way were 2.30% and 0.
80%, whereas in the present embodiment, each is 0.
It was 60% and 0.05%. In this way, the diamond grindstone 17 of this embodiment is used for cutting the magnetic head bar 16.
Is used, the yield is improved.

As described above, in the method of manufacturing the magnetic head of the present invention, in the processing of FIG.
Diamond abrasive grains 20 and second diamond abrasive grains 21
Fig. 4 which is obtained by bonding resin with a resinoid bond material.
By using the diamond grindstone 17 of the present invention in the processing of (b) and FIG. 6 (a) respectively, the occurrence rate of cracks and chippings is reduced in each processing, and the yield is extremely improved.

[0037]

As described above, in the diamond grindstone of the present invention, the first diamond abrasive grains having a particle size of 20 μm to 30 μm and the second diamond abrasive grains having a particle size of 5 μm to 10 μm are used. The phenomenon and clogging phenomenon are reduced, and stable grinding and polishing ability is provided, and cracks and chipping can be reduced.

In the method of manufacturing the magnetic head of the present invention,
Since the magnetic head chip is formed by using the diamond grindstone composed of the first diamond abrasive grains and the second diamond abrasive grains, the occurrence rate of cracks and chippings can be reduced and the yield can be extremely improved.

[Brief description of drawings]

FIG. 1A is a front view of a diamond grindstone according to an embodiment of the present invention, and FIG. 1B is an enlarged partial sectional view of a diamond grindstone according to an embodiment of the present invention.

2 (a) and 2 (b) are schematic diagrams for explaining a state of a diamond grindstone according to an embodiment of the present invention during use.

FIG. 3 is a perspective view of a conventional magnetic head.

4A to 4C are views showing processing of a gap bar of a head structure in a conventional magnetic head manufacturing method.

5A and 5B are views showing joining and processing of a gap bar of a head structure in a conventional method of manufacturing a magnetic head.

6A and 6B are views showing a cutting process and a lapping process of a head structure in a conventional method of manufacturing a magnetic head.

[Explanation of symbols]

 6 Grooves 12 Track Restriction Grooves 16 Magnetic Head Bar 17 Diamond Grindstone 18 Magnetic Head Chip 19 Cutting Surface 20 First Diamond Abrasive Grains 21 Second Diamond Abrasive Grains 22 Binder 23 Voids

Claims (2)

[Claims] 1. A first diamond abrasive grain having a grain size of 20 μm to 30 μm, and a second diamond abrasive grain having a grain size of 5 μm to 10 μm with respect to the first diamond abrasive grain.
A diamond grindstone characterized by being mixed at a ratio of up to 25% by weight and bonded by a binder. 2. A method of manufacturing a magnetic head, wherein a magnetic head chip is processed with the diamond grindstone according to claim 1.