JP2018080065A - Manufacturing method of glass tube - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing method of a glass tube, the manufacturing method being capable of improving a quality of a relatively large-sized glass tube.SOLUTION: A manufacturing method is provided in which a molten glass Ga is formed into a cylindrical shape by flowing down the molten glass Ga along a compact 20, a formed cylindrical shaped molten glass Ga is heated in a heating furnace 30 to make it a softened state, then a glass tube G is formed by solidifying it through a slow cooling, the glass tube G is formed to a predetermined tube diameter and a length with an inside of the glass tube G vacuumed when the formed glass tube G is cut into a predetermined length, the glass tube G is sealed at a predetermined cut position P, and the glass tube G is cut (wrenched off).SELECTED DRAWING: Figure 1

Description

  The present invention relates to a technology of a glass tube manufacturing method, and more specifically, manufacturing of a glass tube capable of manufacturing a glass tube having a relatively large size such as an outer diameter exceeding 50 mm with high dimensional accuracy. It relates to method technology.

Conventionally, various methods, such as the Danner method, the bellows method, and the downdraw method, are known in the manufacturing method of a glass tube. Among these production methods, for example, when producing a relatively large glass tube having an outer diameter exceeding 50 mm, the Dunner method is formed by bending the tube from the vertical direction to the horizontal direction. The bellows method and the downdraw method are often employed because they are easily affected by their own weight.
Here, when manufacturing such a large-sized glass tube, the glass tube before cutting which is still in a softened state due to a change in atmospheric pressure in the glass tube which occurs when the formed glass tube is cut to a desired length. The outer diameter and the wall thickness of the glass tube were likely to fluctuate, and this caused the quality of the glass tube as a final product to deteriorate.

Therefore, a technique for dealing with such a problem is disclosed in, for example, “Patent Document 1”.
That is, in the “Patent Document 1”, a plug is inserted into the tube from the lower end portion of the glass tube to close the inside of the glass tube, and gas is supplied into the tube from the upper end portion of the glass tube through the pipe. Thus, a technique relating to a method of manufacturing a glass tube is disclosed, in which the pressure in the glass tube is controlled so that the pressure difference between the outside and the inside of the glass tube is constant.
Moreover, in the above-mentioned “Patent Document 1”, instead of inserting a plug into the glass tube, a method of surrounding the end of the glass tube with a cutting chamber (pressurizing chamber) together with a cutting device, and cutting the end of the glass tube A method of providing the device in the water tank together with the apparatus is also disclosed as another embodiment.

JP-A-2-296740

According to the method for manufacturing a glass tube in the “Patent Document 1”, even when a large-sized glass tube is manufactured, it becomes possible to greatly suppress fluctuations in the atmospheric pressure in the glass tube at the time of cutting, The quality of the glass tube as the final product can be improved.
However, in such a glass tube manufacturing method, an apparatus for inserting and holding the closing plug into the glass tube becomes large, which causes an increase in equipment cost.
Similarly, when the end portion of the glass tube is surrounded by a cutting chamber (pressurizing chamber) together with the cutting device, or when the end portion of the glass tube is provided in the water tank together with the cutting device, the cutting device or the glass tube after cutting is similarly applied. Since it is necessary to arrange an unloading device or the like in the cutting chamber (pressurizing chamber) or the water tank, the entire facility becomes large and causes an increase in facility cost.

  The present invention has been made in view of the above-described problems of the present situation. A glass tube having a relatively large size is formed, and the formed glass tube is cut at a predetermined cutting location. Glass that is a manufacturing method, can be used to improve the quality of the glass tube as a final product by suppressing the fluctuation of the atmospheric pressure in the glass tube at the time of cutting without providing a large-scale apparatus separately. It is an object to provide a method for manufacturing a pipe.

  The problem to be solved by the present invention is as described above. Next, means for solving the problem will be described.

  That is, in the method for producing a glass tube according to the present invention, the molten glass is formed into a cylindrical shape by flowing down the molten glass along the formed body, and the formed cylindrical molten glass is heated by a heating furnace. A glass tube is formed by solidifying while gradually cooling after being softened, and after the formed glass tube is drawn out to a predetermined length, the glass tube is cut at a predetermined cutting location. It is a manufacturing method of a pipe | tube, Comprising: When pulling out the said glass tube, it carries out, attracting | sucking in the said glass tube.

According to the method for manufacturing a glass tube having such a configuration, a large-scale apparatus is not separately provided.For example, the air pressure in the glass tube at the time of cutting can be changed by a simple configuration including a vacuum pump and a piping member. It is possible to suppress and improve the quality of the glass tube as the final product.
Specifically, for example, even if the gas in the glass tube expands due to heating by a heating furnace and the atmospheric pressure in the glass tube rises, the glass in the glass tube is forcibly sucked to lower the atmospheric pressure. The pressure difference between the outside and the inside of the tube can always be kept substantially constant, the fluctuation of the atmospheric pressure in the glass tube at the time of cutting can be suppressed, and the quality of the glass tube as the final product can be improved.

  Moreover, in the manufacturing method of the glass tube which concerns on this invention, it is preferable to cut | disconnect the said glass tube, after sealing the inside of the tube of the said glass tube including the said cutting part.

  According to the method of manufacturing a glass tube having such a configuration, for example, when cutting a large-sized glass tube, as in the conventional case, the atmospheric pressure in the glass tube located on the upper side of the cut portion fluctuates and the glass tube It is possible to prevent the outer shape and the thickness of the glass tube from fluctuating and cause a deterioration in the quality of the glass tube to be cut thereafter, and the quality of the glass tube as the final product can be maintained.

  Further, in the method for manufacturing a glass tube according to the present invention, in the glass tube, a heating region extending to both ends of the glass tube with the cut portion as a center is heated to be in a softened state, and then the cutting is performed. It is preferable to cut the glass tube by twisting at a location.

  According to the method of manufacturing a glass tube having such a configuration, the lower end portion of the glass tube positioned above the cut portion and the upper end portion of the glass tube positioned below are sealed by their softened parts. In addition, since the glass tube can be twisted (cut) at the cutting point, it is not necessary to provide a sealing device for sealing the inside of the glass tube, and the equipment cost can be reduced. Can do.

  Further, in the method for manufacturing a glass tube according to the present invention, the heating region is heated by a plurality of burners arranged along the heating region, and the plurality of burners are configured such that the length of the flame can be varied. It is preferred that

According to the method for manufacturing a glass tube having such a configuration, for example, by setting the heating power of each burner so as to gradually increase as it approaches the cutting location, the distribution of the amount of heat applied to the glass tube is as follows: It tends to gradually decrease as the distance from the cut portion increases.
As a result, when the glass tube is twisted, in the glass tube, since the softening gradually proceeds from the both sides that are separated from the cutting portion toward the cutting portion, the glass tube is stably cut at the cutting portion. Can be cut.
In addition, when the glass tube is twisted, the outer diameter size of the glass tube is gradually reduced, but by changing the length of the flame of each of the plurality of burners, the thermal power of the burner to the outer peripheral surface of the glass tube is reduced. Can always be kept constant.

  Moreover, in the manufacturing method of the glass tube which concerns on this invention, when cut | disconnecting the said glass tube, it is preferable that the said glass tube is press-contacted by a some guide roller in the said cutting | disconnection location.

According to the method of manufacturing a glass tube having such a configuration, when cutting the glass tube, the cutting portion of the glass tube is regulated at a predetermined position by the plurality of guide rollers, and at the cutting portion, The glass tube can be cut stably.
For example, when the glass tube is cut by twisting, the cutting location of the glass tube is held at a fixed position, so that the torque for twisting the glass tube is stably generated at the cutting location. Can be made.
And the cutting part of a glass tube is press-contacted by a plurality of guide rollers, and the cutting part in the softened state and the surrounding part will be forcibly pushed toward the axis of the glass tube, The twisted portion of the glass tube is more reliably sealed by the pushed-in portion.

As effects of the present invention, the following effects can be obtained.
That is, according to the method for manufacturing a glass tube according to the present invention, even when a relatively large size glass tube is formed and the formed glass tube is cut at a predetermined cutting location, a large-scale apparatus is used. Is not provided separately, and with a simple configuration, fluctuations in the atmospheric pressure in the glass tube at the time of cutting can be suppressed, and the quality of the glass tube as the final product can be improved.

The front cross-sectional schematic diagram which showed the whole structure of the manufacturing apparatus of the glass tube which concerns on one Embodiment of this invention. The enlarged front cross-sectional schematic diagram which showed the vicinity of the sealing device in the manufacturing apparatus of a glass tube.

Next, an embodiment of the invention will be described with reference to FIGS.
In the following description, for convenience, the vertical direction in FIGS. 1 and 2 is described as the vertical direction of the glass tube G manufacturing apparatus 1.
1 and 2, the direction of the arrow A is defined as the drawing direction of the glass tube G.

[Manufacturing equipment 1]
First, the configuration of a glass tube G manufacturing apparatus 1 (hereinafter simply referred to as “manufacturing apparatus 1”) that embodies the glass tube manufacturing method according to the present invention will be described with reference to FIG.

The manufacturing apparatus 1 in this embodiment is an apparatus which manufactures a glass tube continuously by a downdraw method.
Here, as a glass tube manufactured with the manufacturing apparatus 1, the glass tube G of comparatively large size that an outer diameter exceeds 50 mm is mentioned, for example.
More specifically, the glass tube G manufactured by the manufacturing apparatus 1 has, for example, an outer diameter of 125 mm to 200 mm, a wall thickness of 1 mm to 3 mm, and a product length (the total length of the glass tube G as a final product) of 1000 mm. It is a large-sized glass tube having a predetermined dimension of ˜4000 mm.

  The manufacturing apparatus 1 mainly includes a feeder 10, a molded body 20, a heating furnace 30, a sealing device 40, and the like.

The feeder 10 supplies molten glass Ga generated in a melting furnace (not shown) to a heating furnace 30 described later.
The feeder 10 includes a spout 11 filled with molten glass Ga supplied from an upstream melting furnace, an orifice plate 12 having an orifice 12a penetrating in the vertical direction and disposed at the lower end of the spout 11, and Above the orifice plate 12, the tube 13 is inserted from above into the molten glass Ga in the spout 11 and is arranged coaxially with the orifice 12a.

  And the molten glass Ga in the spout 11 is discharged | emitted to the exterior of the feeder 10 through the orifice 12a, and is supplied to the heating furnace 30 which is the next process.

Next, the molded body 20 will be described.
The formed body 20 is used as a bar jig for forming the molten glass Ga into a cylindrical shape (tube shape).
The molded body 20 is composed of a round bar-shaped refractory.
Moreover, the one end part of the molded object 20 is formed as the taper part 20a which gradually reduces in diameter as it goes to the front-end | tip.

The molded body 20 is disposed so as to penetrate the spout 11 in the vertical direction with the tapered portion 20a facing downward.
Further, the molded body 20 is disposed so as to be coaxial with the tube 13 and the orifice 12 a and to protrude downward from the orifice plate 12.
As a result, an annular gap portion 14 is formed between the outer peripheral surface of the molded body 20 and the inner peripheral surface of the orifice 12a.

  The molten glass Ga in the spout 11 is discharged to the outside of the feeder 10 while being formed into a cylindrical shape by flowing down through the gap portion 14 along the outer peripheral surface of the molded body 20.

By the way, a through hole 20 b is formed coaxially with the molded body 20 inside the molded body 20.
Further, the through hole 20b is connected to the vacuum pump 22 via the piping member 21 at the upper end portion thereof.

  Then, as will be described later, when the glass tube is manufactured by the manufacturing apparatus 1, the molten glass Ga (hereinafter referred to as “glass tube G” as appropriate) formed in a cylindrical shape stays in the glass tube. Thus, the gas heated to a high temperature can be sucked from the tapered portion 20a of the molded body 20 by the vacuum pump 22.

Next, the heating furnace 30 will be described.
The heating furnace 30 heats the glass tube G molded along the molded body 20 to a predetermined high temperature state and keeps it warm.
The heating furnace 30 is configured by a so-called muffle furnace.
Specifically, the heating furnace 30 includes, for example, a cylindrical muffle (partition wall) 31 and a plurality of heating wires 32, 32... Arranged along the inner peripheral surface of the muffle 31.

  The heating furnace 30 is suspended at the lower end of the spout 11 so as to be coaxial with the molded body 20 and simultaneously surround the tapered portion 20a of the molded body 20, the orifice plate 12, and the like.

  By having such a configuration, the molten glass Ga flowing down from the feeder 10 along the molded body 20 becomes a glass tube G and continues to pass through the heating furnace 30. At this time, the glass tube G is heated to a predetermined high temperature state by the heating furnace 30, and the high temperature state is maintained.

Here, the “predetermined high temperature state” is a “softened state” in which the outer diameter of the glass tube G can be easily changed simply by changing the internal pressure of the glass tube G (atmospheric pressure in the tube). means.
Then, such a softened state extends over the glass tube G from the lower surface of the orifice plate 12 (the upper end portion of the heating furnace 30) to the point beyond the end portion on the outlet side (lower side) of the muffle 31. It is maintained in the “softening region B”.

Next, the sealing device 40 will be described.
The sealing device 40 draws out the glass tube G formed while the molten glass Ga flows down along the molded body 20 in a predetermined direction (in the present embodiment, in the direction of arrow A and downward). The glass tube G is cut (twisted) after sealing at a predetermined “cutting point P” (cutting point P in FIG. 1).
The sealing device 40 will be described in detail later, but a pair of pipe drawing rollers 41 and 41 arranged in parallel in the vertical direction along the glass tube G, and a pair of pipe drawing rollers 41 and 41 arranged in parallel in the vertical direction. And a plurality of (two in this embodiment) sealing guide rollers 43 and 43 disposed at the center in the vertical direction of the combustion mechanism 42.

Then, the glass tube G suspended from the tapered portion 20a of the molded body 20 is drawn downward by a predetermined length by the pair of tube drawing rollers 41 and 41, and then the predetermined “cutting point P by the combustion mechanism 42. ”And the vicinity thereof are again heated to the“ softened state ”, and backlash in the diameter direction is regulated by the sealing guide roller 41.
In this state, the glass tube G is twisted at the “cutting point P” by the pair of tube drawing rollers 41 and 41. At this time, the glass tube G is twisted (cut) after the inside of the tube is sealed by the vicinity including the “cutting portion P” that has become the “softened state”.
By having such a configuration, in this embodiment, for example, when cutting a large-sized glass tube G as in the prior art, the atmospheric pressure in the glass tube G located above the “cutting point P” fluctuates. As a result, it is possible to prevent the glass tube G from being changed in outer shape and thickness, and subsequently causing a deterioration in the quality of the glass tube G to be cut, thereby maintaining the quality of the glass tube G as a final product. Can be planned.

  As described above, in the manufacturing apparatus 1 according to the present embodiment, the molten glass Ga is formed into a cylindrical shape by flowing down the molten glass Ga along the molded body 20, and the formed cylindrical molten glass Ga is obtained. The glass tube G is formed by solidifying while slowly cooling after being heated by the heating furnace 30 and the formed glass tube G is formed into a predetermined length by a pair of tube drawing rollers 41 and 41. Then, the glass tube G as the final product is manufactured by twisting (cutting) the glass tube G at a predetermined “cutting point P”.

[Sealing device 40]
Next, the configuration of the sealing device 40 will be described in detail with reference to FIG.
The sealing device 40 is mainly configured by a tube drawing roller 41, a combustion mechanism 42, a sealing guide roller 43, and the like.

The tube drawing roller 41 draws the glass tube G downward (in the direction of arrow A) and twists the glass tube G while sealing the glass tube G at a predetermined cutting location (cutting location P in FIG. 2). is there.
The tube drawing roller 41 includes a plurality of rotating rollers 41A, 41A, a support frame 41B that pivotally supports the rotating rollers 41A, 41A,..., And a first drive mechanism that rotationally drives each rotating roller 41A. (Not shown) and a second drive mechanism (not shown) for rotating the plurality of rotating rollers 41A, 41A,... Through the support frame 41B as a whole.

Each rotating roller 41A is made of, for example, a truncated cone-shaped member, and is disposed so as to circumscribe the outer peripheral surface of the glass tube G while the axial direction is substantially horizontal.
Further, the plurality of rotating rollers 41A, 41A,... Having such a configuration are arranged along the periphery of the glass tube G, respectively.
That is, the glass tube G is sandwiched between the plurality of rotating rollers 41 </ b> A, 41 </ b> A, and held by the tube drawing roller 41.

  Each rotary roller 41A is driven to rotate in a predetermined direction (the direction of arrow C in FIG. 2) by the first drive mechanism, and the entire pulling roller 41 has the axis of the glass tube G by the second drive mechanism. The glass tube G is drawn out so as to be drawn downward by being rotationally driven in a predetermined direction (the direction of arrow D in FIG. 2) while being centered.

  In addition, the tube drawing rollers 41 and 41 having such a configuration are provided in two units in one manufacturing apparatus 1, and the glass tube is arranged on the upper side and the lower side with the “cutting point P” of the glass tube G as a center. Each of them is arranged along G.

For example, in this embodiment, the rotational speed V1 in the predetermined direction (the direction of the arrow D) of the tube pulling roller 41 positioned below (hereinafter referred to as “lower tube pulling roller 41D” as appropriate) is the upper side. Is set to be somewhat faster than the rotational speed V2 in a predetermined direction (the direction of the arrow D) of the pipe drawing roller 41 (hereinafter referred to as “upper pipe drawing roller 41U” where appropriate) ( V1> V2).
Thus, by providing a relative speed difference between the rotation speed V1 of the upper tube drawing roller 41U and the rotation speed V2 of the lower tube drawing roller 41D, the glass tube G is placed at the “cutting point P”. And twisted.

Next, the combustion mechanism 42 will be described.
When the glass tube G is twisted by the tube drawing roller 41, the combustion mechanism 42 heats and softens the “cutting portion P” and the upper and lower regions of the glass tube G, and seals the twisted portion of the glass tube G. To do.
The combustion mechanism 42 includes a plurality of burners 42A, 42A,..., And a combustion circuit (not shown) that can arbitrarily change the fire power (flame length) of these burners 42A, 42A,. Composed.

The plurality of burners 42A, 42A,... Are a plurality of “heating points P1, P2,. -In P6, it arrange | positions around the said glass tube G by planar view, respectively.
Further, the plurality of burners 42A, 42A,... Are arranged in the vertical direction along the heating region S including a plurality of “heating points P1, P2,.

  Specifically, a plurality of pieces (supported in a cross-sectional view in FIG. 2) are supported around the “cutting point P” of the glass tube G so that flames are ejected toward the “cutting point P” from obliquely above. Therefore, only two burners 42A, 42A (hereinafter referred to as “first upper burner 42A11” as appropriate) and a flame are ejected from obliquely downward toward “cutting point P”. A plurality of burners 42A, 42A (hereinafter referred to as “first lower burner 42A12” as appropriate) are glass tubes in plan view. G is arranged radially around G.

In addition, the glass tube G is supported around the “heating point P1” spaced apart from the “cutting point P” by a predetermined distance so as to emit a flame from the obliquely upward direction toward the “heating point P1”. A plurality of burners 42A, 42A (hereinafter referred to as “second upper burner 42A21” as appropriate) are centered on the glass tube G in a plan view. Thus, they are arranged radially.
On the other hand, the glass tube G is supported around the “heating point P2” spaced apart from the “cutting point P” by a predetermined distance so that a flame is jetted from the diagonally downward toward the “heating point P2”. A plurality of burners 42A, 42A (hereinafter referred to as “second lower burner 42A22” where appropriate) are shown in plan view as shown in FIG. Arranged radially from the center.

Further, the glass tube G is supported around the “heating point P3” spaced apart from the “heating point P1” by a predetermined distance so as to emit a flame from the obliquely upward direction toward the “heating point P3”. A plurality of burners 42A, 42A (hereinafter referred to as “third upper burner 42A31” where appropriate) are centered on the glass tube G in plan view. Thus, they are arranged radially.
On the other hand, around the “heating point P4” spaced apart from the “heating point P2” in the glass tube G by a predetermined interval, the glass tube G is supported so that a flame is jetted from the diagonally downward toward the “heating point P4”. A plurality of burners 42A, 42A (hereinafter referred to as “third lower burner 42A32” where appropriate) are shown in plan view as shown in FIG. Arranged radially from the center.

Further, in the glass tube G, around the “heating point P5” spaced apart from the “heating point P3” by a predetermined distance, the flame is blown from the diagonally upward toward the “heating point P5”. A plurality of burners 42A, 42A (hereinafter referred to as “fourth upper burner 42A41” as appropriate) are centered on the glass tube G in a plan view. Thus, they are arranged radially.
On the other hand, around the “heating point P6” spaced apart from the “heating point P4” in the glass tube G by a predetermined interval, the glass tube G is supported in such a manner that a flame is jetted from the diagonally downward toward the “heating point P6”. A plurality of burners 42A, 42A (hereinafter referred to as “fourth lower burner 42A42” where appropriate) are shown in a plan view. Arranged radially from the center.

  The heating powers of the first upper burner 42A11 and the first lower burner 42A12 are set to be equal to each other, and the first heating on the glass tube G is performed by the first upper burner 42A11 and the first lower burner 42A12. Zone Z1 is formed.

  Further, the heating powers of the second upper burner 42A21 and the second lower burner 42A22 are set to be equal to each other. The second upper burner 42A21 and the second lower burner 42A22 apply a second heating on the glass tube G. Zone Z2 is formed.

  Further, the heating powers of the third upper burner 42A31 and the third lower burner 42A32 are set to be equal to each other, and the third heating burner 42A31 and the third lower burner 42A32 apply a third heating on the glass tube G. Zone Z3 is formed.

  Further, the heating powers of the fourth upper burner 42A41 and the fourth lower burner 42A42 are set to be equal to each other. The fourth upper burner 42A41 and the fourth lower burner 42A42 perform the fourth heating on the glass tube G. Zone Z4 is formed.

  In the combustion mechanism 42 having such a configuration, the heating power of each of the burners 42A, 42A... Is set so as to gradually increase as it approaches the “cutting point P”.

Specifically, the heating powers of the first upper burner 42A11 and the first lower burner 42A12 for heating the first heating zone Z1 are set most strongly, and the second upper burner 42A21 for heating the second heating zone Z2 and The heating power of the second lower burner 42A22 is set slightly weaker than the heating power of the first upper burner 42A11 (or the first lower burner 42A12).
Further, the heating power of the third upper burner 42A31 and the third lower burner 42A32 for heating the third heating zone Z3 is set slightly weaker than the heating power of the second upper burner 42A21 (or the second lower burner 42A22). In addition, the heating power of the fourth upper burner 42A41 and the fourth lower burner 42A42 for heating the fourth heating zone Z4 is slightly higher than the heating power of the third upper burner 42A31 (or the third lower burner 42A32). It is set weakly.

Therefore, the distribution of the amount of heat applied to the glass tube G through the combustion mechanism 42 is the largest at the “cutting point P” as shown by the region T in FIG. It tends to gradually decrease with time.
As a result, when the glass tube G is twisted by the tube drawing roller 41, the glass tube G is gradually softened from the upper and lower sides of the “cutting point P” toward the “cutting point P”. For this reason (that is, since the softening of the “cutting point P” is most advanced), the glass tube G is stably cut at the “cutting point P”.

  When the glass tube G is twisted by the tube drawing roller 41, the outer diameter size of the glass tube G is gradually reduced in the plurality of heating zones Z1, Z2, Z3, and Z4. The flame length of the plurality of burners 42A, 42A,... Is automatically adjusted by the above-described combustion circuit (not shown), and the glass tube G is set for each of the plurality of heating zones Z1, Z2, Z3, Z4. The heating power of the burners 42A, 42A,.

By the way, in the glass tube G, the range of the heating region S heated by the plurality of burners 42A, 42A... (That is, the vertical range on the glass tube G) is set as follows.
That is, the range of the heating region S corresponds to a portion of the glass tube G that is necessary for sealing the cut portion of the glass tube G when the glass tube G is twisted by the tube drawing rotary roller 41. Set as
That is, in order to seal the cut portion of the glass tube G, it is necessary to soften the amount of the glass tube G within the range of the heating region S based on the inner diameter size of the glass tube G.

Next, the sealing guide roller 43 will be described.
The sealing guide roller 43 is an example of a guide roller that regulates the position of the glass tube G. When the glass tube G is twisted (cut) by the tube drawing roller 41, the “cutting point P” of the glass tube G is used. To hold the position of the “cutting point P”.
The sealing guide roller 43 is made of a disk-shaped member, and the peripheral edge thereof is formed in a taper shape in sectional view.

  And a plurality of sealing guide rollers 43, 43... Are provided in one manufacturing apparatus 1 (only two are shown because it is a sectional view in FIG. 2), and “cutting point P” in the glass tube G is provided. Are arranged so that the axis is parallel to the axis of the glass tube G.

  In addition, each sealing guide roller 43 is supported so as to be rotatable about an axis, and is moved in a proximity / separation direction (horizontal direction in the present embodiment) with respect to the glass tube G by an actuator (not shown). Configured to be possible.

  When the sealing guide roller 43 is moved toward the glass tube G by the actuator, the glass tube G is pressed against the peripheral edge of the sealing guide roller 43 at the “cutting point P”. It has come to be.

  In this way, when each sealing guide roller 43 · 43 ··· moves in the proximity direction with respect to the glass tube G, the glass tube G includes the plurality of sealing guide rollers 43 · 43 · · ·. And the “cutting point P” of the glass tube G is regulated at a predetermined position.

As a result, when the glass tube G is twisted by the tube drawing roller 41, the “cutting point P” of the glass tube G is held at a fixed position, so that the torque for twisting the glass tube G is stabilized. Can be generated at the “cutting point P”.
In addition, the “cutting point P” of the glass tube G is pressed by the sealing guide roller 43, so that the “cutting point P” in the “softened state” and the surrounding part are in the axis of the glass tube G. The glass tube G is forcedly pushed in, and the twisted portion of the glass tube G is more reliably sealed by the pushed portion.

[Operation Procedure of Sealing Device 40]
Next, when manufacturing the glass tube G with the manufacturing apparatus 1, the operation | movement procedure at the time of twisting (cutting), sealing the glass tube G with the sealing apparatus 40 is demonstrated using FIG. 1 and FIG. To do.

First, as shown in FIG. 1, the molten glass Ga flows down along the molded body 20, so that a cylindrical glass tube G is formed.
Further, the formed glass tube G is in a state of hanging from the lower end portion (tapered portion 20a) of the molded body 20, and its upper end portion is located in the heating furnace 30, while its lower end portion is a sealing device. 40 is sandwiched between a pair of tube drawing rollers 41 and 41.

The vacuum pump 22 is in an operating state, and the air in the glass tube G is always sucked.
Further, in the heating furnace 30, the temperature in the muffle 31 is in a state of being heated to a predetermined temperature by the heating wire 32.

Further, in the sealing device 40, the plurality of rotation rollers 41A, 41A,... Provided in each tube drawing roller 41 is in a state in which the rotation drive is stopped, and the tube drawing roller 41 via the support frame 41B. The rotation drive as a whole is also stopped.
Moreover, each of the plurality of burners 42A, 42A,... Constituting the combustion mechanism 42 is in a state in which the ejection of flame is stopped.
Further, the plurality of sealing guide rollers 43, 43... Are stopped at standby positions separated from the glass tube G.

In such a state, as shown in FIG. 2, the plurality of rotating rollers 41 </ b> A, 41 </ b> A,... In each of the tube drawing rollers 41 starts to rotate all at once in a predetermined direction (the direction of arrow C). At the same time, the tube pulling roller 41 as a whole starts to rotate in a predetermined direction (the direction of arrow D).
At this time, in the pair of tube drawing rollers 41 and 41, the rotation speed V2 of the entire upper tube drawing roller 41U and the rotation speed V1 of the entire lower tube drawing roller 41D are set to be equal to each other (V1 = V2). ).

As a result, the glass tube G is drawn downward by the pair of tube drawing rollers 41 and 41.
Thus, in the present embodiment, the glass tube G is drawn downward by the pair of tube drawing rollers 41 and 41 while the vacuum pump 22 always performs the suction operation in the glass tube G.
By having such a configuration, for example, even if the gas in the glass tube G expands due to heating by the heating furnace 30 or the combustion mechanism 42 and the atmospheric pressure in the glass tube G increases, the inside of the glass tube G The pressure difference between the outside and inside of the glass tube G can always be kept substantially constant by forcibly sucking in the gas and lowering the atmospheric pressure, and the “softening region B” of the upper glass tube Gu is affected. Therefore, it is possible to prevent the outer shape and thickness from fluctuating and maintain the quality of the glass tube G as the final product.

When the lower end of the glass tube G reaches a predetermined position (that is, when the length from the “cutting point P” to the lower end of the glass tube G reaches a predetermined length), it is the same as the speed at which the glass tube G descends. The plurality of burners 42A, 42A,... And the plurality of guide rollers 43, 43,... Descend, and the plurality of burners 42A, 42A,.
At this time, as described above, the length of the flame ejected from the plurality of burners 42A, 42A,... Is automatically adjusted to a predetermined length set for each burner 42A.

After that, after a flame has spouted from the plurality of burners 42A, 42A, etc., when a predetermined time elapses, the plurality of sealing guide rollers 43, 43,. To do.
As a result, the glass tube G is in a state of being pressed by the plurality of sealing guide rollers 43, 43,... At the “cutting points P” softened by heating by the plurality of burners 42A, 42A,.

  When a plurality of sealing guide rollers 43, 43,... Are pressed against the "cutting point P" of the glass tube G, the rotational speed V1 of the entire lower tube drawing roller 41D is lowered between the pair of tube drawing rollers 41, 41. Starts the rotational drive so that it is somewhat faster than the rotational speed V2 of the entire upper pulling roller 41U (V1> V2).

  As a result, in the glass tube G, a portion above the “cutting portion P” (hereinafter referred to as “upper glass tube Gu” as appropriate) and a portion below the “cutting portion P” (hereinafter referred to as “lower” as appropriate). Relative to the glass tube Gd ”), and the glass tube G is twisted at the“ cutting point P ”by the pair of tube drawing rollers 41 and 41. .

  As described above, in the present embodiment, the heating region S extending in the both end sides (that is, the upper and lower end sides) of the glass tube G around the “cutting portion P” in the glass tube G is heated. After the “softened state”, the glass tube G is cut by twisting at the “cutting point P”.

  As a result, at the lower end portion of the upper glass tube Gu and the upper end portion of the lower glass tube Gd, when the glass tube G is twisted, the portions softened by the plurality of burners 42A, 42A,. Immediately rising toward the inner peripheral portion of the tube G, and immediately before being twisted at the “cutting point P”, the lower end portion of the upper glass tube Gu and the upper end portion of the lower glass tube Gd are sealed.

Thus, in this embodiment, after sealing the lower end part of the upper side glass tube Gu and the upper end part of the lower side glass tube Gd with the softened own site | part, the glass tube G is "cut | disconnected location P". It is configured to be twisted (cut).
Therefore, conventionally, when cutting a large-sized glass tube G, the atmospheric pressure in the upper glass tube Gu fluctuates, and accordingly, the outer shape of the upper glass tube Gu in the “softening region B (see FIG. 1)” The variation in the wall thickness causes the quality of the glass tube G (that is, the lower glass tube Gd) as a final product to deteriorate, but in this embodiment, the lower end of the upper glass tube Gu. Is sealed, it is possible to suppress such fluctuations in the atmospheric pressure in the upper glass tube Gu, and to prevent the outer shape and thickness of the upper glass tube Gu in the “softening region B” from fluctuating. Thus, the quality of the glass tube G as the final product can be maintained.

  When the glass tube G is twisted at the “cutting point P”, the plurality of sealing guide rollers 43, 43,... Move in the separating direction with respect to the glass tube G, and the plurality of burners 42A, 42A,. .. And each of the plurality of burners 42A, 42A,... And the plurality of guide rollers 43, 43,.

In the pair of tube pulling rollers 41 and 41, the setting is switched so that the rotation speed V2 of the entire upper tube pulling roller 41U and the rotation speed V1 of the entire lower tube pulling roller 41D are equal to each other (V1). = V2).
As a result, the upper glass tube Gu and the lower glass tube Gd are both drawn downward at the same speed.

Thereafter, the lower glass tube Gd that has been twisted (cut) passes through the lower tube pulling roller 41D and is carried out of the manufacturing apparatus 1.
In addition, the upper glass tube Gu hanging from the molded body 20 (see FIG. 1) is sandwiched between the pair of tube drawing rollers 41 and 41 by having its lower end passing through the lower tube drawing roller 41D. Become.

  Then, the upper glass tube Gu is then drawn further downward, and when the lower end of the upper glass tube Gu reaches a predetermined position, the above-described procedure is repeated. Thereby, a glass tube can be obtained continuously.

20 Molded body 30 Heating furnace 42A Burner 42A11 First upper burner 42A12 First lower burner 42A21 Second upper burner 42A22 Second lower burner 42A31 Third upper burner 42A32 Third lower burner 42A41 Fourth upper burner 42A42 Fourth lower Side burner 43 Sealing guide roller G Glass tube Ga Molten glass P Cutting location S Heating area

Claims (5)

Forming the molten glass into a cylindrical shape by flowing down the molten glass along the molded body,
After the molded cylindrical molten glass is softened while being heated by a heating furnace, a glass tube is formed by solidifying while slowly cooling,
After the formed glass tube is drawn out to a predetermined length, the glass tube is cut at a predetermined cutting location, which is a method of manufacturing a glass tube,
When pulling out the glass tube, while sucking the inside of the glass tube,
A method of manufacturing a glass tube. After sealing the inside of the glass tube and the vicinity of the tube including the cut portion,
Cutting the glass tube,
The manufacturing method of the glass tube of Claim 1 characterized by the above-mentioned. In the glass tube, after heating the heating region that extends to both ends of the glass tube with the cut portion as a center, to be in a softened state by heating,
Cutting the glass tube by twisting at the cutting point;
The manufacturing method of the glass tube of Claim 1 or Claim 2 characterized by the above-mentioned. The heating region is
Heated by a plurality of burners arranged along the heating area,
The plurality of burners are:
Each is configured to be variable in flame length,
The manufacturing method of the glass tube of Claim 3 characterized by the above-mentioned. In cutting the glass tube,
The glass tube is pressed by a plurality of guide rollers at the cutting location,
The manufacturing method of the glass tube as described in any one of Claims 1-4 characterized by the above-mentioned.

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