JPH10130027A - Production of glass preform material and apparatus therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To inexpensively produce glass preform materials in glass mold forming. SOLUTION: A plurality of grinding means 5 having grinding wheels 9 formed with hemispherical recessed parts 12 as grinding surfaces, motors for rotating these grinding wheels and lifting means 11 for lifting the grinding wheels and the motors are arranged at prescribed intervals. Polishing means 7 having polishing wheels 9 formed with the hemispherical recessed parts 15 as polishing surfaces are arranged at the same intervals as the prescribed intervals behind these grinding means. The apparatus is provided with feeding means for intermittently feeding glass blanks 3 at the same pitches as the intervals and produces the preform materials 2 by subjecting these glass blanks to respective grinding stages and polishing stages when the feed operation of these feeding means is held stopped.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technique for inexpensively producing a glass preform in glass molding.

[0002]

2. Description of the Related Art In a glass molding method, a predetermined volume of a preform material is charged into a closed space formed by a mold and a mold die, and a heating step, a pressing step,
The final product is obtained through a cooling step and the like.

[0003] In such a glass molding method, injection molding cannot be performed unlike a synthetic resin molding method. Therefore, it is necessary to form the preform material so that the volume thereof becomes accurate.

[0004] That is, since glass molding requires a preform material having almost the same volume as the volume of the closed space, it is necessary to precisely control the volume.

[0005] The shape of the conventional glass preform material is generally a sphere whose volume can be easily controlled.

[0006]

However, the above-mentioned spherical glass preform material is cut into a predetermined size from a glass lump, for example, a cubic glass material is cut with a wire cut, a hand saw, or the like, and the glass preform is cut. The top and ridge lines of the material are rounded by barrel polishing, etc., then the abrasive grains are gradually refined with a double-sided lapping machine, etc., and finally polished to obtain a spherical glass preform material of a predetermined size. It has gained. Therefore, there is a problem that the molding process requires time, labor, and the like, and the cost is high.

Accordingly, an object of the present invention is to reduce the cost of a glass preform material.

[0008]

In order to solve the above-mentioned problems, a method of manufacturing a glass preform material according to the present invention is to grind a glass material with a grindstone having a rotating body-shaped concave portion as a grinding surface. Thus, a glass preform having at least one surface having the same shape as the concave portion and having a predetermined volume is manufactured.

Therefore, according to the method for producing a glass preform material of the present invention, since the glass preform material is formed only by the grinding step, the molding processing time is short, and the preform material is inexpensive without any labor. Can be manufactured.

Further, the apparatus for producing a glass preform material according to the present invention comprises a grindstone having a rotating body-shaped concave portion as a grinding surface, a motor for rotating the grindstone, and elevating means for moving the grindstone and the motor up and down. And a grinding wheel rotated by the elevating means is brought into contact with the glass material, and the glass material is ground to obtain a preform material having at least one surface having the same shape as the concave portion.

Therefore, according to the apparatus for manufacturing a glass preform material of the present invention, the glass preform material can be manufactured only by the grinding step, the molding time is short, and the preform material is inexpensive without any labor. Materials can be manufactured.

[0012]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a glass preform material manufacturing method according to the present invention;

FIGS. 1 to 8 show a first embodiment of a method and an apparatus for manufacturing a glass preform material according to the present invention, which is applied to a case where a hemispherical glass preform material 2 is manufactured. Things.

An apparatus 1 for manufacturing a glass preform material comprises:
A feeding means 4 for feeding a glass material 3 which is a workpiece, and three grinding means 5, 5 for stepwise grinding the glass material 3 sent by the feeding means 4 to a predetermined shape and size;
5 and a polishing means 7 for polishing a preform material scheduled portion 6 having a predetermined size and shape by the plurality of stages of grinding means 5, 5, 5.

The glass material 3 is in the form of a flat plate and is appropriately fixed to the stage 8 of the feeding means 4. By intermittently feeding the stage 8 at a predetermined pitch p, the glass material 3 is moved at a predetermined pitch p. It is sent intermittently.

The grinding means 5 has a grinding wheel 9 as a processing head, a motor 10 for rotating the grinding wheel 9, and an elevating means 11 for raising and lowering the grinding wheel 9 and the motor 10.

The three grinding means 5, 5, 5 are glass material 3
Are arranged at a predetermined interval in the same direction as the feeding direction, and the predetermined interval matches the intermittent feeding pitch p of the stage 8 of the feeding means 4. The glass material 3 has a part facing the first grinding means 5a in a part facing the second grinding means 5b by this feeding operation, and a part facing the second grinding means 5b.
The parts opposing the third grinding means 5c are sent by this feeding operation so as to come to the parts opposing the third grinding means 5c.

The number of the preforms 2 that can be obtained from one glass material 3 can be increased by making the distance between the grinding means 5 as small as possible.

The elevating means 11 moves the grinding wheel 9 and the motor 10 in a direction perpendicular to the surface of the glass material 3, and the elevating operation of each elevating means 11 is controlled separately. The lifting means 11 may be moved up and down in conjunction with each other. In this case, since the descent speed and time of the grinding wheel are the same for each grinding process, it is necessary to control the rotation speed of each motor 10 and the like. Thus, it is preferable to optimize the grinding state in each grinding step.

The grinding wheel 9 is formed in a columnar shape, and a hemispherical concave portion 12 is formed in the lower end surface thereof, and its peripheral edge is formed to be relatively thin, and is directly attached to the motor shaft of the motor 10. I have. The roughness of the grinding wheel 9a of the first grinding means 5a is # 240-320, and the roughness of the second grinding means 5b
The roughness of the grinding wheel 9b is # 800, and the third grinding means 5
The roughness of the grinding wheel 9c of #c is formed at # 1500, and the ground surface is gradually smoothed in the process of grinding the glass material 3.

The depth of the concave portion 12 is slightly smaller than the thickness of the glass material 3.
When the polishing is completed, the preform material 2 is simultaneously separated from the glass material 3 at the same time. That is, the depth of the recess 12 is equal to the third grinding wheel 9c.
Recess 12c of the second grinding wheel 9b,
The depth of the recess 12c of the third grinding wheel 9c is slightly smaller than the thickness of the glass material 3. This is because the glass material 3 is slightly cut by grinding and polishing to become the preform material 2 as a final product, and therefore, a cutting allowance in each of the following grinding steps is left.

The polishing means 7 has almost the same configuration as the above-mentioned grinding means 5, and instead of the grinding wheel 9 of the grinding means 5, an abrasive, for example, CeO ₂ (cerium oxide) is made of a synthetic resin material such as epoxy. The grinding wheel 13 is directly attached to a motor shaft of a motor 14.

The grinding wheel 13 has substantially the same shape and size as the above-mentioned grinding wheel 9, and has a recess 15 formed on the lower end surface in the same manner as the grinding wheel 9. The glass material 3 is moved at right angles by the lifting means 16. Also, the concave portion 1 of the grinding wheel 13
5 has the same depth as the thickness of the glass material 3.

Such a polishing means 7 is disposed on the subsequent step side of the third grinding means 5c at the same interval as the feed pitch p of the feed means 4 from the third grinding means 5c.
As a result, the glass material 3 is fed by the feeding operation of the feeding means 4 for one pitch p so that the portion facing the third grinding means 5a comes to a position facing the polishing means 7 by this feeding operation. .

Thus, the glass material 3 is fed by the feeding means 4, and when the preform material scheduled portion 6a is located below the first grinding means 5a, the first grinding means 5a is driven, As the motor 10a is rotated, the grinding wheel 9a is lowered by the lifting / lowering means 11a, and the preform material scheduled portion 6a of the glass material 3 is ground. At this time, the lowering of the grindstone 7a by the elevating means 11a stops just before the apex of the concave portion 12a comes into contact with the upper surface of the glass material 3, and the depth of the concave portion 12a is made slightly shallower than the thickness of the glass material 3. Therefore, the preform material scheduled portion 6 a is not cut from the glass material 3.

Further, the descent of the grinding wheel 7a is stopped immediately before its apex contacts the upper surface of the glass material 3. When the apex of the concave portion 12a of the whetstone 7a, which is the center of rotation, comes into contact with the glass material 3, the preform material This is because a portion corresponding to the apex of the portion 6a is not ground and a portion called a so-called "navel" is generated.

The grinding wheel 9a (# 240-320)
Since the bottom edge is formed thin, the grinding resistance is small and the grinding process can be performed smoothly.

Then, the preform material scheduled site 6a is
After being ground to some extent close to the shape (hemisphere) of the preform material 2 which is the final product, the first
Finishes the grinding process.

Next, the glass material 3 is fed by the feeding means 4, and the preform material expected portion 6a is moved below the second grinding means 5b. At this time, a new preform material scheduled portion 6b is moved below the first grinding means 5a. Then, the second grinding means 5b and the first
The preform material planned portions 6a and 6b are ground by the grinding means 5a.

In the second grinding means 5b, the first grinding means
Since the grinding is performed by the grinding wheel 9b (# 800) finer than the grinding wheel 9a (# 240 to 320) of the grinding means 5a, the surface of the preform material scheduled portion 6a is further smoothed.

Further, the glass material 3 is fed by the feeding means 4.
To move the preform material expected portion 6a below the third grinding means 5c, and move the preform material expected portion 6b below the second grinding means 5b. At this time, the new preform material scheduled portion 6c is moved below the first grinding means 5a. Then, the preform material scheduled portions 6a, 6b and 6c are formed by the third grinding means 5c, the second grinding means 5b and the first grinding means 5a.
Are respectively ground.

In the third grinding means 5c, the second grinding means 5c is used.
In order to perform grinding with a grinding wheel 9c (# 1500) finer than the grinding wheel 9b (# 800) of the grinding means 5b,
The surface of the preform material scheduled portion 6a is further smoothed.

At the end of the third grinding step, the depth of the recess 12c of the third grinding wheel 9c is
Since the thickness of the preform material is slightly shallower than the thickness of the glass material 3, the preform material planned portion 6 a is not cut out from the glass material 3.

Next, the glass material 3 is fed by the feeding means 4, the preform material expected portion 6a is positioned below the polishing means 7, and the preform material expected portion 6b is moved to the third position.
And the preform material planned portion 6c is positioned below the second grinding means 5b. At this time, a new preform material scheduled site 6d
Is located below the first grinding means 5a. The planned preform material portion 6a is polished by the polishing means 7, and the preform material planned portion 6b is polished by the third grinding means 5c, the second grinding means 5b, and the first grinding means 5a.
Grind each of 6c and 6d.

In the polishing means 7, the surface of the preform material scheduled portion 6a is roughly polished in order to perform polishing with a finer grinding wheel 13 (CeO ₂ ) than the grinding wheel 9c (# 1500) of the third grinding means 5c. Can be mirrored.

Since the depth of the concave portion 15 of the grinding wheel 13 is formed to be the same as the thickness of the glass material 3, the preform material expected portion 6 a is cut off from the glass material 3 at the same time as the completion of the polishing step. It becomes the preform material 2.

In this way, the glass material 3 is intermittently forwarded by the feeding means 4 and, at the time when the feeding is stopped, the respective grinding and polishing steps are performed.
.. Are sequentially manufactured.

In the first embodiment, the concave portions 12 and 15 formed in the grinding wheel 9 and the polishing wheel 13, respectively.
Is shown as a hemisphere, but the present invention is not limited to this, and such a concave portion may have a shape of a rotating body, and may satisfy the shape of the preform material 2 to be manufactured. Should be fine.

Further, in the above-described embodiment, a description has been given of a case where the grinding step is performed in three stages. However, the present invention is not limited to this. Can also.

Further, in the above embodiment, a plurality of grinding steps and one polishing step are sequentially performed on one glass material. The first grinding step is performed by the first grinding means, the glass material is then fed by the feeding means, the second grinding steps by the plurality of second grinding means are performed simultaneously, and the glass material is fed by the feeding means. Alternatively, a large number of preform materials may be manufactured from one glass material at the same time, such as performing the third grinding step by a plurality of third grinding means simultaneously. Such a method can be applied to each embodiment described below.

FIGS. 9 to 11 show a second embodiment of the method and apparatus for manufacturing a glass preform material according to the present invention.

The difference between the second embodiment 1A and the first embodiment 1 is that the preform material is separated from the glass material not in the same time as the end of the polishing step but in another step. Since only the points described above are used, other parts are given the same reference numerals as those of the same parts in the method and apparatus for manufacturing a glass preform material according to the first embodiment. Therefore, the description thereof will be omitted.

Glass preform material manufacturing apparatus 1A
Means for feeding glass material 3A;
A grinding means 5,5,5 for grinding A, a grinding means 7 for grinding the ground glass material 3A, and a separating means 17 for separating the polished preform material planned portion 6A from the glass material 3A.

The separating means 17 has a cylindrical core drill 18, a motor 19 for rotating the core drill 18, and an elevating means 20 for elevating and lowering the core drill 18.

The inner diameter of the core drill 18 is formed to be the same as the inner diameter of the opening of the recess 15 of the grinding wheel 13.

The separating means 17 is provided on the subsequent side of the polishing means 7 from the polishing means 7 to the feed means 4.
Is arranged at the same interval as the feed pitch p of the glass material 3A, so that the glass material 3A is moved from the preform material scheduled portion 6A facing the polishing means 7 by the feed operation of one pitch p of the feed means 4. The paper is sent so as to come to a position facing the separating means 17 by the feeding operation.

The glass material 3A to be introduced into the glass preform material manufacturing apparatus 1A is a slightly thicker plate-like glass material than the glass material 3 used in the first embodiment, and is used in the polishing step. At the time of completion, the preform material scheduled portion 6A is not separated from the glass material 3A.

After the polishing step of the polishing means 7 is completed, the periphery of the preform material scheduled portion 6Aa facing the separating means 17 is cut off by the core drill 18 so that the preform material is cut. The intended material portion 6A is cut off from the glass material 3A, and a hemispherical preform material 2A is manufactured.

According to the second embodiment, each of the grinding wheels 9, 9, 9 and the recesses 12, 12, 1 of the polishing wheel 13 are formed.
The dimensional accuracy of the depth of 2, 15 and the thickness of the glass material 3A can be roughened.

In the second embodiment, the separating means is provided on the same side as the grinding means and the polishing means and the glass material. However, the present invention is not limited to this. It may be arranged on the opposite side.

FIGS. 12 to 15 show a third embodiment of the method and apparatus for manufacturing a glass preform material according to the present invention, which is applied to the case of manufacturing a spherical glass preform material. is there.

The difference between the third embodiment 1B and the second embodiment 1A is that the grinding step and the polishing step are performed on both surfaces of the glass material. In the drawings, the same reference numerals are given to the same parts as those in the method and apparatus for manufacturing a glass preform material according to the second embodiment, and description thereof will be omitted. In the third embodiment 1B, the first to third glass materials are interposed between the polishing step (hereinafter, referred to as “first polishing step”) and the cutting step in the second embodiment 1A. From the surface (lower surface) opposite to the surface (upper surface) on which the grinding process and the first polishing process were performed, and the same grinding as in the first to third grinding processes and the first polishing process for the preform material expected portion Process and polishing process.

First, a glass material 3B having a thickness almost twice that used in the second embodiment 1A is used.

Further, as a post-process of the first polishing means 7a, the fourth to sixth grinding means 5d, 5e, 5f combine the first to third grinding means 5a, 5b, 5c with the glass material 3B. The distance between each of the fourth to sixth grinding means 5d, 5e, and 5f and the distance between the fourth grinding means 5d and the first grinding means 7a are the same as those of the feed means 4. The interval is the same as the feed pitch p.

The grinding wheel 9d of the fourth grinding means 5d has a roughness of # 240-320, the roughness of the grinding wheel 9e of the fifth grinding means 5e has a roughness of # 800, and the grinding of the sixth grinding means 5f. The grindstone 9f has a roughness of # 1500.

Further, as a post-process of the sixth grinding means 5f, the second polishing means 7b is connected to the fourth to sixth grinding means 5f.
d, 5e, 5f, that is, on the lower surface side of the glass material 3B, the interval between the sixth grinding means 5f is arranged to be the same as the feed pitch p of the feed means 4; 2
Polishing means 7b is similar to the first polishing means 7a.
For example, a material in which CeO ₂ is contained in a synthetic resin material such as epoxy is used as the grinding wheel 13b.

The separating means 17 is arranged at the same interval as the feed pitch p of the feed means as a post-process of the second polishing means 7b.

After finishing the first to third grinding steps and the first polishing step on the upper surface of the glass material 3B as in the second embodiment 1A, the glass material 3B is
The preform material scheduled portion 6B on the lower surface side of the glass material 3B is ground and polished by the feeding means 4 intermittently by the sixth to sixth grinding means 5d, 5e, 5f and the second polishing means 7b.

That is, after the completion of the first polishing step, the glass material 3B fed by one pitch p by the feeding means 4 is:
The planned preform material site 6Ba is the fourth grinding means 5
d is located above the grinding wheel 9d, and the fourth grinding means 5
d is driven, the motor 10d is rotated, and the grinding wheel 9d is raised by the lifting / lowering means 6d, so that the preform material expected portion 6Ba of the glass material 3B is ground from the lower surface side.

Then, the preform material scheduled portion 6Ba
However, when it has been ground to some extent close to the shape (spherical shape) of the preform material 2B, which is the final product, the fourth grinding step ends.

Similarly, the glass material 3B is fed by the feeding means 4
, And the preform material planned portion 6Ba is sequentially ground by the fifth and sixth grinding processes.

After the completion of these grinding steps, the glass material 3B is further fed by the feeding means 4, and the preform material expected portion 6Ba is positioned above the second polishing means 7b, and the second polishing means 7b Is used to polish the preformed material scheduled portion 6Ba.

In the second polishing means 7b, the first polishing means
The same grinding wheel 13 as the grinding wheel 13a of the polishing means 7a
Since the polishing is performed by b (CeO ₂ ), the surface of the preform material scheduled portion 6Ba can be made almost mirror-finished.

The glass material 3B to be supplied to the apparatus 1B for manufacturing a glass preform material in the second embodiment.
Is a plate-like glass material having a thickness approximately twice that of the glass material 3B used in the second embodiment. At the end of the second polishing step, the preform material scheduled portion 6B is not cut off,
The preform material scheduled portion 6Ba is formed with annular grooves 21 and 21 that open upward or downward on both upper and lower surfaces thereof, and a thin portion 22 is formed between each deep portion.

After the polishing step of the second polishing means 7b is completed, the preform material planned portion 6Ba facing the separating means 17 is moved around the periphery of the preform material planned portion 6Ba by the core drill 18, that is, the thin portion 22 is formed. As a result, the preform material planned portion 6B is
B and the preform material 2B.

In this way, the glass material 3B is intermittently forwarded by the feeding means 4 and, at the time when the feeding operation is stopped, each grinding step and polishing step are performed, whereby the spherical glass preform is successively formed. Material 2B, 2
B are produced.

[0067]

As is apparent from the above description, the invention according to claim 1 is characterized in that at least one surface is ground by grinding a glass material with a grindstone having a rotating body-shaped concave portion as a grinding surface. The same shape as the concave portion, and, so as to produce a glass preform material having a predetermined volume, it is possible to mold the glass preform material only in the grinding process, molding processing time is short, The preform material can be manufactured at low cost without any trouble.

The invention according to claim 2 includes a plurality of grinding steps, in which the glass material is intermittently fed at a predetermined pitch, and the glass material is ground in each of the above-mentioned grinding steps when the feeding operation is stopped. In addition, the same shape as the concave portion of the grinding surface of the grindstone in the final grinding step of the above-mentioned grinding step, and, so as to produce a glass preform material having a predetermined volume, so that the glass is continuously fed forward A preform material can be manufactured.

The invention described in claims 3 and 4 is
After the grinding process, the preformed material that has been subjected to the grinding process is separated from the glass material.Therefore, it is not necessary to separate the preform material from the glass material at the same time as the completion of the grinding process. The dimensional accuracy such as the thickness and the thickness of the glass material can be roughened.

The invention described in claims 5 to 7 is:
Since the above-mentioned grinding process is performed on both sides of the plate-shaped glass material at the same portion, a glass preform material having a desired shape that is convex on both sides of the glass material can be obtained.

In the invention described in claims 8 to 13, since the final grinding step is a polishing step, a mirror-shaped preform material can be obtained.

According to a fourteenth aspect of the present invention, there is provided a grinding wheel having a rotating body-shaped recess as a grinding surface, a motor for rotating the grinding wheel, and a lifting means for lifting and lowering the grinding wheel and the motor. Then, the rotating grindstone is brought into contact with the glass material by the elevating means, and the glass material is ground to obtain a preform material in which at least one surface has the same shape as the concave portion, so that the glass preform material is ground. The preform material can be manufactured only by the process, the molding processing time is short, and the preform material can be manufactured at low cost without any trouble.

The invention according to claim 15 has a plurality of grinding means and a feeding means for feeding the glass material intermittently at a predetermined pitch, and when the feeding operation of the feeding means is stopped, each of the above-mentioned glass materials is removed. Grinding by the grinding means, the same shape as the concave portion of the grinding surface of the grindstone in the final grinding means of the above grinding means, and, so as to produce a glass preform material having a predetermined volume, continuous continuous feeding Thus, a glass preform material can be manufactured.

According to the present invention, after the glass material is ground by the above-mentioned grinding means to form a preform material scheduled portion having a predetermined shape, the preform material scheduled portion is removed from the glass material. Since the separation means is provided, it is not necessary to separate the preform material from the glass material at the same time as the completion of the grinding process, and the dimensional accuracy such as the depth of the concave portion of the grinding stone and the thickness of the glass material can be reduced. Can be.

In the invention according to claims 18 to 20, the grinding means is disposed on both sides of the glass material, and the glass material is ground on the same portion from both sides by the grinding means. It is possible to obtain a glass preform material having a desired shape that is convex on both sides of the glass material.

According to the present invention, since the final grinding means is a polishing means, a mirror-shaped preform material can be obtained.

The specific shape or structure of each part shown in each of the above embodiments is merely an example of the method of manufacturing the glass preform material of the present invention and the embodiment of the apparatus. However, the technical scope of the present invention should not be interpreted in a limited manner.

[Brief description of the drawings]

FIG. 1 schematically shows a first embodiment of a method and an apparatus for manufacturing a glass preform material of the present invention, together with FIGS. 2 to 8, and is a schematic side view of the entire apparatus.

FIG. 2 is a schematic side view showing a state in which a first grinding step is performed on a first preform material scheduled portion.

FIG. 3 is a schematic side view showing a state where a second grinding step is being performed on a first preform material scheduled portion.

FIG. 4 is a schematic side view showing a state where a third grinding step is being performed on a first preform material scheduled portion.

FIG. 5 is a schematic side view showing a state in which a polishing step is being performed on a first preform material scheduled portion.

FIG. 6 is a schematic side view showing a state in which a preform material is formed after a polishing step for a first preform material scheduled portion is completed.

FIG. 7 is an enlarged schematic side view showing a grinding state in a grinding step.

FIG. 8 is an enlarged schematic side view showing a polishing state in a polishing step.

FIG. 9 schematically illustrates a second embodiment of the method and apparatus for manufacturing a glass preform material of the present invention, together with FIGS. 10 and 11, and FIG. 9 is a schematic side view of the entire apparatus.

FIG. 10 is a schematic side view showing a state in which a cutting step is being performed on a first preform material scheduled portion after the polishing step.

FIG. 11 is a schematic side view showing a state where a first preform material planned site is cut off to obtain a preform material.

FIG. 12 schematically shows a third embodiment of the method and apparatus for manufacturing a glass preform material of the present invention, together with FIGS. 13 to 15, and is a schematic side view of the entire apparatus.

FIG. 13 is a schematic side view showing a state in which a cutting step is being performed on a first preform material scheduled portion after a second polishing step is completed.

FIG. 14 is a schematic side view showing a state in which a first preform material scheduled portion is cut off to obtain a preform material.

FIG. 15 is an enlarged schematic side view showing a second polishing step and a separation step.

[Explanation of symbols]

1, 1A, 1B ... an apparatus for manufacturing a glass preform material,
2, 2A, 2B ... glass preform material, 3, 3A,
3B: glass material, 4: feeding means, 5: grinding means, 6,
6A, 6B: Preformed material planned site, 9: Grinding wheel,
10, 14 ... motor, 11, 16 ... elevating means, 12, 1
5 recess, 13 grinding wheel, 17 separating means, p
Predetermined pitch

Claims (26)

[Claims] 1. A glass preform material in which at least one surface has the same shape as the concave portion and has a predetermined volume by grinding the glass material with a grindstone having a rotary body-shaped concave portion as a grinding surface. And a method for producing a glass preform material. 2. The method according to claim 1, further comprising a plurality of grinding steps, wherein the glass material is intermittently fed at a predetermined pitch, and the glass material is ground in each of the grinding steps when the feeding operation is stopped. 2. A glass preform material having the same shape as the concave portion of the grinding surface of the grinding wheel in the final grinding step and having a predetermined volume is manufactured.
3. The method for producing a glass preform material according to item 1. 3. The method for producing a glass preform material according to claim 1, wherein, after the grinding step, the preformed material portion subjected to the grinding step is separated from the glass material. 4. The method for producing a glass preform material according to claim 2, wherein, after the grinding step, the preformed material portion subjected to the grinding step is separated from the glass material. 5. The method for producing a glass preform material according to claim 2, wherein said grinding step is performed on both sides of a plate-shaped glass material at the same site. 6. The method for producing a glass preform material according to claim 3, wherein said grinding step is performed on both sides of the same portion of the plate-like glass material. 7. The method for manufacturing a glass preform material according to claim 4, wherein said grinding step is performed on both sides of a plate-shaped glass material at the same site. 8. The method for manufacturing a glass preform material according to claim 2, wherein the final grinding step is a polishing step. 9. The method for producing a glass preform material according to claim 3, wherein the final grinding step is a polishing step. 10. The method according to claim 4, wherein the final grinding step is a polishing step. 11. The method for producing a glass preform material according to claim 5, wherein the final grinding step is a polishing step. 12. The method for manufacturing a glass preform material according to claim 6, wherein the final grinding step is a polishing step. 13. The method for manufacturing a glass preform material according to claim 7, wherein the final grinding step is a polishing step. 14. A grindstone having a rotating body-shaped concave portion as a grinding surface, a motor for rotating the grindstone, and a grinding means comprising lifting means for lifting and lowering the grinding wheel and the motor, wherein the grinding means comprises: An apparatus for manufacturing a glass preform material, characterized in that a grinding stone to be brought into contact with a glass material and the glass material is ground to obtain a glass preform material having at least one surface having the same shape as the concave portion. 15. A grinding machine comprising: a plurality of grinding means; and a feeding means for feeding a glass material intermittently and at a predetermined pitch, wherein the glass material is ground by each of the grinding means when the feeding operation of the feeding means is stopped. 15. The glass according to claim 14, wherein a glass preform material having the same shape as the concave portion of the grinding surface of the grindstone in the final grinding means of the grinding means and having a predetermined volume is manufactured. Equipment for manufacturing preform materials. 16. A method according to claim 1, further comprising the step of: cutting the glass material by the grinding means to form a preform material scheduled portion having a predetermined shape, and then separating the preform material scheduled portion from the glass material. An apparatus for producing a glass preform material according to claim 14. 17. A cutting means for cutting a preform material scheduled portion of a predetermined shape from a glass material after forming the preform material scheduled portion of a predetermined shape by grinding the glass material by the grinding means. An apparatus for manufacturing a glass preform material according to claim 15. 18. The method according to claim 15, wherein the grinding means is provided on both sides of the glass material, and the glass material is ground on the same portion from both sides by the grinding means. Equipment for manufacturing glass preforms. 19. The method according to claim 16, wherein the grinding means is provided on both sides of the glass material, and the glass material is ground on the same portion from both sides by the grinding means. Equipment for manufacturing glass preforms. 20. The method according to claim 17, wherein the grinding means is provided on both sides of the glass material, and the glass material is ground from both sides of the same portion by the grinding means. Equipment for manufacturing glass preforms. 21. The apparatus according to claim 15, wherein the final grinding means is a polishing means. 22. The apparatus for manufacturing a glass preform material according to claim 16, wherein the final grinding means is a polishing means. 23. The apparatus for producing a glass preform material according to claim 17, wherein the final grinding means is a polishing means. 24. The apparatus for producing a glass preform material according to claim 18, wherein the final grinding means is a polishing means. 25. The apparatus for producing a glass preform material according to claim 19, wherein the final grinding means is a polishing means. 26. The apparatus for manufacturing a glass preform material according to claim 20, wherein the final grinding means is a polishing means.