JP2000344534A - Glass rod production apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a glass rod production apparatus which is capable of stably manufacturing the glass rod to be used for glass joining of a pair of, for example, a pair of magnetic head cores to constitute a magnetic head without being affected by the quality of glass raw material and the shape and size of a crucible at high accuracy. SOLUTION: The position, in a second heater 3, of the nozzle tip part 2 of a drawing out nozzle 1, which extends downwardly perpendicularly and is disposed at the bottom end of the crucible 5 into which the glass raw material 6 is fed, is specified to put the glass drawn out of the nozzle tip 2 to a desired stable state, by which the variation of the diameter of the glass rod formed between rollers 9 and 10 is suppressed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for manufacturing a glass rod used when, for example, a pair of magnetic head cores serving as a magnetic head are glass-bonded.

[0002]

2. Description of the Related Art Conventionally, for manufacturing a magnetic head mounted on, for example, a video tape recorder (hereinafter, referred to as "VTR"), a glass rod formed in a rod shape is melted. So-called glass bonding (also referred to as "glass bonding" or "glass fusion") in which a pair of magnetic core halves are bonded and integrated is performed. This glass bonding is performed, for example, as shown in FIG. 5, by a pair of magnetic core half blocks 12, 1 serving as a magnetic core half.
3 is manufactured in advance, and the pair of magnetic core half blocks 12 and 13 are abutted. Thereafter, the glass groove 14 and the winding groove 1 formed in one magnetic core half block 12 are formed.
5, the glass rod 11 is penetrated in the longitudinal direction, and the glass rod 11 is heated and melted. Then, as shown in FIG. 6, the molten glass 16 is filled in the vicinity of the open end of the winding groove 15 and the joint portion where the depth of the glass groove 14 and the magnetic gap is zero, for fusion or embedding. By this, it is joined and integrated.

[0003] The glass rod used in the manufacturing process of such a magnetic head is formed in a rod shape in terms of controlling the amount of glass melting and the glass setting work efficiency. There are many ways.
A typical one of them is to heat a crucible containing a glass raw material by a heater, draw out the liquid glass melted by the heating from a small-diameter draw-out nozzle, and adjust a fixed wire diameter between a pair of rollers. The so-called "pull-down method" is used for manufacturing. In the glass rod manufacturing apparatus used in the conventional "pulling-down method", a heating device for heating the drawer nozzle is provided separately from the heater for the drawer nozzle.

[0004]

By the way, in recent years, VT
With the performance improvement of magnetic heads in the field of magnetic heads mounted on R and the like and the miniaturization of heads and the increase in the number of types of heads, the glass bonding requires "higher precision of glass rods independent of the distance between rods and the material". Is strongly required. However, in the conventional "pull-down method", when the glass is manufactured in a rod shape, the wire diameter of the glass rod varies among lots in which the raw materials are put into the crucible, and the wire diameter accuracy of the glass rod is remarkably reduced. At present, lots are sometimes manufactured. In addition, in order to sufficiently draw out the characteristics of the head, glass in which the coefficient of thermal expansion and the fusing temperature of glass are variously changed is required, but the crucible shape is changed depending on the material or the desired glass rod size, At present, there is a difference in the wire diameter accuracy of the glass rod by changing the crucible size. Therefore, when a glass rod having such a problem is actually used for glass bonding of a magnetic head, the yield related to the production of the glass rod is reduced, the inspection is abolished, and an extra part is required when the glass rod is fused. Glass or a shortage of glass causes a decrease in yield or the like, which has a large effect on the product value of the magnetic head. On the other hand, glass rods are used in large quantities for fusing or embedding magnetic head cores,
Considering the costs involved in manufacturing the magnetic head, it has become a significant problem that cannot be ignored. For this reason,
It is of course conceivable to solve such a problem by making mechanical improvements to the device. However, this leads to an increase in cost, which is not preferable.

The present invention has been made in view of the above circumstances, and in a so-called pulling-down method, a glass rod having a high wire diameter accuracy is stable throughout all lots without being affected by variations between lots and differences in materials. It is an object of the present invention to provide a glass rod manufacturing apparatus which can be manufactured by using the method.

[0006]

The present invention has been made as a result of intensive studies to solve the above-mentioned problems. As a result, the above-mentioned problems can be solved simply by adding simple improvements without mechanically improving the apparatus. It has been found that a high-precision glass rod that overcomes the above problem can be manufactured. In the conventional production of glass rods, setting the position of the drawer nozzle was not special. For this reason, every time a material is charged and a glass rod is manufactured, the accuracy of the diameter of the glass rod deteriorates due to the difference between lots, and moreover, each time the material or the desired glass rod size changes, the crucible shape is changed, By changing the diameter, the accuracy of the diameter of the glass rod was deteriorated. In order to achieve the above object, the present invention is directed to an apparatus for manufacturing a glass rod used when joining members to glass, the apparatus comprising: a crucible into which a glass raw material is charged; A drawer nozzle that extends vertically downward from the lower end of the drawer and draws out the liquid glass melted in the crucible from the nozzle tip, and covers the drawer nozzle, and the lower end is disposed further below the nozzle tip of the drawer nozzle. A heating means for heating the entire drawing nozzle, and a heating means disposed below the tip of the nozzle and opposed to each other so as to form a semi-solid glass having a predetermined wire diameter and sent out from the tip of the nozzle. The drawer nozzle is located at a position closest to the lower end of the heating means, and the liquid gas in that portion is located at the position closest to the lower end of the heating means. It constitutes a glass rod manufacturing apparatus that the temperature of the scan is disposed at a position to hold the set temperature.

As described above, according to the glass rod manufacturing apparatus of the present invention, the position of the tip of the nozzle from which the liquid glass is drawn is specified, whereby the shape of the glass rod pulled out from the nozzle and cooled to a semi-solid state is determined. Is stable, and it is possible to stably produce low-cost, high-quality glass rods without changing the shape or size of the crucible, regardless of the lot or material.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the glass rod manufacturing apparatus according to the present invention will be described below in detail with reference to the drawings. In addition, since the following description is a preferable specific example of the present invention, various technically preferable limitations are added, but the scope of the present invention is not limited to the following description, in particular, to limit the present invention. It is not limited to these embodiments unless otherwise stated. First, the overall structure of the glass rod manufacturing apparatus of the present invention will be described with reference to FIG. The crucible 5 supported by the cradle 8 comprises an enlarged diameter portion 5a into which the glass raw material 6 is charged, and a drawer nozzle 1 vertically connected to the lower end of the enlarged diameter portion 5a and extending downward. The nozzle tip 2 at the lower end of the drawer nozzle 1 is opened. Around the enlarged diameter portion 5a of the crucible 5, a first heater 7 of heating means for heating and melting the glass raw material 6 in the enlarged diameter portion 5a is provided. Around the drawing nozzle 1, a second heater 3 of a heating device for further heating the liquid glass 6a dropped from the enlarged diameter portion 5a to the drawing nozzle 1 side to a suitable set temperature is arranged. As shown, the lower end 4 of the second heater 3 is disposed at a position further lower than the nozzle tip 2 of the drawer nozzle 1. As shown, the glass 6b drawn out of the nozzle tip 2 and cooled into a semi-solid state passes through a gap between a pair of rollers 9 and 10 disposed immediately below the nozzle tip 2 and has a predetermined wire diameter d. Manufactured as a glass rod. Of course, the heating temperature of the first and second heaters 7, 3 and the rollers 9, 1
The gap between 0 and the like is formed so as to be adjusted to a desired state by a control adjusting means (not shown).

The glass rod manufacturing apparatus of the present invention has the above-mentioned structure, but is characterized in that the position of the nozzle tip 2 of the drawing nozzle 1 is specified.
The specific method will be described with reference to FIGS. 3 and 4 and Table 1 below.

[0010]

[Table 1]

Table 1 shows the standard deviation and the like of the glass rods manufactured under the conditions described in the vertical columns for Comparative Examples 1 to 6 and the examples. The contents described in the examples correspond to the present invention. This corresponds to an embodiment of a glass rod manufacturing apparatus. As shown in Table 1, the diameter of the glass melting tank for the Examples and Comparative Examples 1 to 6 (the diameter of the crucible 5) was 60.
mm and a constant shape. Also,
Internal diameter of drawer nozzle 1 8mm, lot pulling speed 2
m / min, target rod diameter of glass rod 0.530m
m, glass rod length 190 mm, etc. were all constant.
Further, those having constant thermal expansion coefficient, glass transition point temperature and glass yield point temperature of the used glass raw material were used.

Under the above conditions, the number of sampling measurements n = 1
Table 1 shows the measurement results of the wire diameters of the glass rods manufactured for Example and Comparative Examples 1 to 6 at 00, and are shown in FIGS. 3 and 4, respectively. The “nozzle position from the outlet” in Table 1 represents the distance a from the nozzle tip 4 to the lower end 4 of the second heater 3 in FIGS. 1 and 4, and specifically, a = 50 mm in the embodiment. The values corresponding to a in Comparative Examples 1 to 6 are 70 mm, 80 mm, and 90 m.
m, 40 mm, 30 mm, and 20 mm.

On the other hand, the drawer nozzle 1 is heated by the second heater 3. In the present embodiment, the set value (set temperature) of the heating temperature is set to 520 ° C. As shown in FIG. 1, the drawing nozzle 1 is uniformly heated by the second heater 3, but the liquid glass 6 a is cooled at the moment of being drawn out from the nozzle tip 2, so that the liquid glass 6 a at the nozzle tip 2 is cooled. The temperature 6a does not always match the set temperature depending on the position of the nozzle tip 2. That is, as shown in FIG. 4, in the case of Comparative Example 6, the dimension a up to the nozzle tip 2 is 20 mm, which is closest to the lower end 4 of the second heater 3. Therefore, the effective temperature of this portion is lower than the predetermined temperature of 520 ° C. of the second heater 3, and the temperature of the liquid glass 6 a at the nozzle tip 2 at this position is about 450 ° C. as shown in Table 1. FIG. 4 shows this state. When the above effective temperatures were measured for Comparative Examples 5, 4, 3, 2, 1 and the examples, as shown in Table 1, 480
° C, 500 ° C, 520 ° C, 520 ° C, 520 ° C, 520
° C, and only the comparative examples 1, 2 and 3 and the embodiment match the set temperature with the effective temperature. As described above, the second heater 3
Even if the drawer nozzle 1 is heated evenly by the
Since the lower end 4 of the heater 3 is open, the temperature in the second heater 3 near the lower end 4 decreases, the temperature of the liquid glass 6a at the nozzle tip 2 decreases accordingly, and the temperature reaches the set temperature. It will not be heated. If the glass 6b is not heated to the set temperature, the glass 6b drawn out of the nozzle tip portion 2 and rapidly cooled is semi-solidified, and the molding by the rollers 9 and 10 becomes unstable.

On the other hand, as described above, when the position of the nozzle tip 2 moves away from the lower end 4 of the second heater 3, the effective temperature of the liquid glass 6a at the nozzle tip 2 matches the set temperature. Nozzle tip 2 depending on the position of 2
Since the liquid glass 6a drawn out of the roller 6 is not rapidly cooled and drawn out while being heated by the second heater 3, the semi-solid state of the glass 6b sent to the rollers 9 and 10 does not become a desired state and the molding is not stable. Results.

As shown in Table 1, under the above conditions, n
The results of measuring the wire diameter d for = 100 are shown for the examples and comparative examples 1 to 6. Table 1 shows the wire diameter d.
The maximum wire diameter, the minimum wire diameter, the average wire diameter, and the standard deviation (variation) are described. FIG. 3 shows standard deviations of the embodiment and comparative examples 1 to 6. According to Table 1 and FIG. 3, in Comparative Example 6 where the position of the nozzle tip 2 is closest to the lower end 4 of the second heater 3 and Comparative Example 3 where it is farthest, a desired glass rod is not actually formed. On the other hand, the standard deviation of the comparative example 5 near the lower end 4 and the comparative example 2 far from the lower end 4 are poor, and it can be seen that a position with the smallest standard deviation exists at an intermediate position between them. In the present embodiment, the position of a = 50 mm in the example is the best condition.

As described above, when the position of the nozzle tip 2 is close to the lower end 4 of the second heater 3, the effective temperature of the liquid glass 6a at the nozzle tip 2 is lowered, and a stable glass rod is obtained. I can't. On the other hand, if it is far away, the effective temperature matches the set temperature, but it is not cooled to an appropriate temperature in the state where it is pulled out from the nozzle tip 2 and is further heated by the second heater 3, so that a stable glass rod is obtained in this case as well. Therefore, there is a position of a condition that is just right. This embodiment satisfies this condition, and the most stable glass rod can be manufactured if the nozzle tip 2 is disposed at a position of a = 50 mm in FIG.

Next, a method of setting up the glass rod manufacturing apparatus 1 so as to satisfy the above conditions and stably manufacturing the glass rod will be described with reference to the flowcharts of FIGS. In order to manufacture a glass rod using the apparatus for manufacturing a glass rod according to the present embodiment, the second heater 3 is previously heated to about the desired glass rod fusion temperature (flow chart 1). Then, the temperature distribution inside the second heater 3 is measured as described above (flow chart 2). Based on the temperature distribution result, a position close to the lower side of the second heater 3 on the drawer side is confirmed under the set temperature condition (flow chart 3). Then, the height of the receiving table 8 is set in advance so that the nozzle tip 4 of the extraction nozzle 1 of the crucible 5 comes to the aforementioned position (flow chart 4).
Thereafter, the glass raw material 6 is weighed (flowchart 5), put into the crucible 5 (flowchart 6), and the crucible 5 is set (flowchart 7). Then the first
Is heated (Flowchart 8), and the melting, stirring, and fining (bubble removal) steps are performed as needed (Flowchart 9). On the other hand, the interval and the rotation speed between the pair of rollers 9 and 10 are adjusted according to the desired wire diameter and length of the glass rod (flow chart 10). Thereafter, the heater 3 is heated (flowchart 11), and the glass material 6 having an appropriate viscosity is dropped from the drawing nozzle 1 (flowchart 12) and sandwiched between a pair of rollers 9 and 10 (flowchart 13). Rollers 9, 10
(Flow chart 14). The glass rod manufactured in this way is used after being cut into a predetermined length. As described above, the present invention sets the position of the drawer nozzle 1 to the position closest to the lower part on the drawer side while maintaining the set temperature of the second heater 3 without adding various control mechanisms and mechanical improvements of the apparatus. The above-mentioned "Improvement of glass rod accuracy regardless of lot-to-lot and material, crucible shape and crucible size"
Can be manufactured.

[0018]

According to the glass rod manufacturing apparatus of the present invention, the glass melting raw material drawn out from the drawing nozzle is rapidly cooled by setting the drawing nozzle at the position closest to the lower part on the drawing side while maintaining the set temperature of the heater. Thus, it is possible to stably produce a high-precision glass rod that is not affected by the distance between rods, the material, the shape of the crucible, and the size of the crucible. Therefore, when actually used for glass joining of a variety of magnetic heads, the yield related to the production of glass rods is reduced, inspection is eliminated, and furthermore, defects due to excess glass or shortage of glass during fusion are reduced. Can be done. As a result, since the glass rod is used in a large amount for fusing or embedding the magnetic head core, the cost for manufacturing the magnetic head can be significantly reduced.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view schematically showing an overall schematic structure of a glass rod manufacturing apparatus of the present invention.

FIG. 2 is a flowchart for explaining a method of manufacturing a glass rod by the glass rod manufacturing apparatus of the present invention.

FIG. 3 is an explanatory diagram showing a comparison of standard deviations between the embodiment of the present invention and Comparative Examples 1 to 6.

FIG. 4 is an explanatory diagram showing a comparison between the internal temperature of the heater (approximately the temperature at the nozzle tip) of the embodiment of the present invention and Comparative Examples 1 to 6.

FIG. 5 is a perspective view showing a state before a glass rod is set in a groove of a ferrite block in a conventional glass bonding (gap bonding) step during magnetic head processing.

FIG. 6 is a perspective view showing a state in which a ferrite block is filled with glass.

[Explanation of symbols]

1 ... Drawer nozzle, 2 ... Nozzle tip, 3 ... Second heater, 4 ... Bottom, 5 ... Crucible, 5a ... Expanded diameter section, 6 ... Glass raw material, 6a ... Liquid glass, 6b ...
Glass, 7 first heater, 8 cradle, 9 rollers, 10 rollers.

Claims (1)

[Claims] 1. An apparatus for manufacturing a glass rod used for joining glass members to each other, the apparatus comprising: a crucible into which a glass material is charged; and a crucible extending vertically downward from a lower end of the crucible. A drawer nozzle for drawing the liquid glass melted from the nozzle tip portion, and heating for covering the drawer nozzle and having a lower end disposed further below the nozzle tip portion of the drawer nozzle and heating the entire drawer nozzle. And a pair of rollers disposed below the nozzle tip and opposed to each other to form a semi-solid glass drawn out from the nozzle tip to a predetermined wire diameter. The position of the nozzle tip of the drawer nozzle is closest to the lower end of the heating means, and the temperature of the liquid glass in that portion is maintained at a set temperature. Glass rod manufacturing apparatus characterized by being arranged to.