KR20040000922A - Apparatus and method for manufacturing glass tube - Google Patents

Abstract

PURPOSE: An apparatus for making a glass tube is provided to form a glass tube having a fine diameter precisely and efficiently at an improved yield and to change the dimension of the glass tube with ease. CONSTITUTION: The apparatus for making a glass tube comprises: a feeder(30) connected to the downstream of a glass melting furnace(10) and equipped with stepwise orifices in which the surface areas of the orifices are reduced stepwise downwardly to draw the melted glass(2); a heating means(32) around the feeder(30) for controlling the temperature of the feeder(30) and the viscosity of the melted glass(2); a forming die(40) mounted on the orifices of the feeder(30) and having a mandrel(42) that guides the flow of the melted glass(2) drawn through the orifices in the shape of a tube; an extrusion die(50) disposed in continuous to the forming die(40) and determining the outer diameter of the melted glass(2) passing through the orifices of the feeder(30); and a drawing means(60) for drawing a glass tube(3) passing through the extrusion die(50).

Description

Apparatus and method for manufacturing glass tube {APPARATUS AND METHOD FOR MANUFACTURING GLASS TUBE}

The present invention relates to an apparatus and method for manufacturing a glass tube, and more particularly, to an apparatus and method for manufacturing a glass tube capable of precisely and efficiently producing a narrow glass tube by continuously drawing the glass straight down by adjusting the viscosity of the molten glass. It is about.

As is well known, a cold cathode fluorescent lamp is mainly used to configure a backlight unit of a liquid crystal display (LCD) and is an important component for determining the brightness and chromaticity of the backlight unit. In the cold cathode fluorescent lamp, rare earth gas and mercury encapsulated in the glass tube are excited by the discharge between two electrodes attached to both ends of the glass tube, and ultraviolet rays (253.7 nm) generated by the excited mercury electrons are applied to the inner surface of the glass tube. Collide with the phosphor. The phosphor generates visible light as a light source of the backlight unit, and the wavelength of the phosphor may be determined by the composition. On the other hand, cold cathode fluorescent lamps, such as copiers, facsimile machines, scanners, office equipment such as copiers, evacuation induction, various advertising panels, etc. are widely used.

As the glass tube of such a cold cathode fluorescent lamp, borosilicate glass having an outer diameter of 5.2 mm or less and a thickness of 0.6 mm or less is commonly used. Recently, due to the thinner, lighter and lower power consumption of the liquid crystal display device, the glass tube of the fluorescent lamp for the backlight unit has an outer diameter of 3.0 mm or less and a thickness of 0.3 mm or less, which further reduces thinning and thinning. It is required.

In general, glass tubes of cold-cathode fluorescent lamps are manufactured by the Velo process, also called the Danner process and the Down-draw process. It is suitable for the production of glass tubes of 70 mm.

In the production of the glass tube by the mononer method, the melting glass supplied from the Forehearth of the glass melting furnace is continuously supplied to the rotating refractory cylinder inclined. The hot molten glass is drawn while being transferred to the lower end of the refractory cylinder, and air is introduced into the molten glass through the refractory cylinder. The molten glass is formed into a glass tube by the inflow of air, and a glass tube having a continuous length is manufactured by sufficiently maintaining the air pressure for forming the hollow tube. And the glass tube to be drawn is rotated while being transported by a horizontal conveyor.

In the production of the glass tube by the bellows method, the molten glass supplied from the glass to the glass melting furnace is vertically drawn through the annular space surrounding the fire tube through which air is flowed, and is formed into a glass tube. The glass tube is rotated while being transported by a horizontal conveyor. At this time, by adjusting the pressure of the air, the drawing speed of the molten glass, the temperature and the like to adjust the diameter and thickness of the glass tube is drawn to produce the desired glass tube.

In both the Danner method and the Bellow method, the glass tube of continuous length is drawn on a horizontal conveyor, and the glass tube is rotated during drawing to satisfy the dimensional conditions of the glass tube. However, in the Danner method and the bellow method, since the air is blown for forming the glass tube, the drawing speed of the glass tube is fast, the size error is large, so the accuracy is low, and the bending phenomenon occurs. In addition, because of the large size of the glass melting furnace has a disadvantage that a lot of equipment cost should be invested.

On the other hand, in order to manufacture a narrow glass tube having an outer diameter of about 2 to 5 mm suitable for a cold cathode fluorescent lamp, the glass tube is manufactured by the Danner method which employs a small fireproof cylinder. have. In addition, due to the quantitative imbalance that forms a glass tube of less than 1/10 of the amount of glass dissolved in the glass melting amount, there is a disadvantage in that the efficiency of the melting loss is large. Further, after the mother glass tube having a large outer diameter is manufactured by the Danner method and the bellow method, the narrow glass tube is manufactured by a redraw process in which it is reheated while being reheated using a preform. However, the reflow method has a disadvantage in that the manufacturing cost increases due to the increase in the number of processes, and the yield is low.

The present invention has been made to solve various problems of the prior art as described above, an object of the present invention is to accurately and efficiently produce a narrow glass tube having an outer diameter of about 1 to 5mm, thickness of about 0.1 to 0.6mm An apparatus and method for manufacturing a glass tube are provided.

Another object of the present invention is to provide an apparatus and a method for producing a glass tube which can improve the yield greatly by appropriately and efficiently maintaining a quantitative balance between the amount of melting into the glass melt and the molding amount of the glass tube.

Another object of the present invention can be produced by simply changing the dimensions of the glass tube by the control of the forming die, extrusion die and drawing speed, fine quality fine diameter without the bending phenomenon suitable for the production of cold cathode fluorescent lamp without blowing air The present invention provides an apparatus and a method for producing a glass tube that can produce a glass tube.

A feature of the present invention for achieving this object is a stepped orifice connected to the downstream of the glass melting furnace for dissolving the glass raw material into the molten glass, and the cross-sectional area is gradually reduced toward the downstream to draw the molten glass directly downward Feeder is formed; Heating means surrounding the feeder to control the temperature of the feeder to adjust the viscosity of the molten glass; A forming die mounted to the orifice of the feeder, the forming die having a mandrel capable of guiding the flow of molten glass drawn through the orifice of the feeder; An extrusion die mounted to be continuous with the forming die and determining an outer diameter of the molten glass passing through the orifice of the feeder; An apparatus for producing a glass tube comprising drawing means for drawing a glass tube passing through an extrusion die.

Another feature of the present invention is the step of dissolving the glass raw material into the molten glass in the glass melting furnace and feeding the downstream feeder; Controlling the temperature of the feeder to adjust the viscosity of the molten glass; Tubularly forming the molten glass through a stepped orifice, a forming die and an extrusion die of the feeder; It is a manufacturing method of the glass tube which consists of drawing the glass tube hardened by passing through an extrusion die directly below.

1 is a cross-sectional view showing an apparatus for manufacturing a glass tube according to the present invention;

Figure 2 is a partially enlarged cross-sectional view showing the configuration of the orifice, the forming die and the extrusion die of the feeder in the apparatus for producing a glass tube according to the present invention;

3 is a cross-sectional view taken along line II of FIG. 2;

4 is a cross-sectional view taken along the line II-II of FIG. 2;

5 is a front view showing the configuration of a drawing device in the apparatus for manufacturing a glass tube according to the present invention;

6 is a flowchart illustrating a method for manufacturing a glass tube according to the present invention.

♣ Explanation of symbols for the main parts of the drawing ♣

2: molten glass 3: glass tube

10: glass melting furnace 11: melter

12: Refiner 13: Muirus

14: plunger 20: air supply device

30: feeder 31: orifice

32: heater 40: forming die

42: mandrel 50: extrusion die

60: drawing device 61: capstan roller

62: motor 63: electric machine

70: laser interference measuring instrument 80: controller

Hereinafter, a preferred embodiment of the apparatus and method for manufacturing a glass tube according to the present invention will be described in detail with reference to the accompanying drawings.

First, referring to FIG. 1, the apparatus for manufacturing a glass tube according to the present invention includes a glass melting furnace 10 for dissolving and supplying a glass raw material 1 called a batch into a molten glass 2. The glass melting furnace 10 includes a melter 11 which substantially dissolves the injected glass raw material 1 into the dissolving glass 2, and bubbles and dissimilar glass that dissolve the dissolving glass 2 supplied from the melter 11. A refiner 12 for thermally, chemically and physically homogenizing to be removed, and a mux 13 for homogenizing and homogenizing the molten glass, are continuously connected. The melter 11, the refiner 12, and the ground 13 of the glass melting furnace 10 are all constructed of refractory materials.

In addition, a dog house (11a) for injecting the glass raw material (1) upstream of the melter (11) is formed, and in the downstream to form a flow path of the molten glass (2) connected to the refiner (12) Throat 11b spaced from is formed. Downstream of the refiner 12, a throat 12a spaced from the bottom is formed so as to form a flow path of the molten glass 2 which is connected to the shingles 13. Throat 13a is formed in the center of the bottom of the spur 13, and the plunger 14 which opens and closes the throat 13a by a lifting motion is provided in the spur 13. As shown in FIG. The plunger 14 controls the flow rate of the molten glass 2 drawn out by opening and closing the throat 13a of the balance 13 while being elevated by the hydraulic cylinder 15 as an operation means. The operation means may comprise a servomotor, a lead screw rotated by the drive of the servomotor, and a nut screwed along the lead screw and fixed to the plunger 14.

Each of the melter 11, refiner 12, and duster 13 of the glass melting furnace 10 includes a plurality of electric boosting devices that provide thermal energy for dissolving the glass raw material 1 and the molten glass 2. device: 16) is installed. The electric booster 16 may be composed of a plate-shaped platinum electrode plate or a rod-shaped molybdenum electrode bar and a ground electrode. When a high voltage is applied to each of the platinum electrode or molybdenum electrode, the molten glass 2 itself acts as a resistance heating element to generate heat by generating electrical resistance, thereby sufficiently dissolving the glass raw material 1 and the molten glass 2. have. And the melter 11 of the glass melting furnace 10 is provided with a gas burner well known as a heating means for heating up the melter 11 for the initial operation of the glass melting furnace 10. The refiner 12 and the lance 13 of the glass melting furnace 10 supply air for cooling to the upper layer of the molten glass 2 for conditioning, ie, homogenization and homogenization of the molten glass 2. The duct 21 of the supply apparatus 20 is connected. Air supply device 20 may be configured with a well-known blower.

On the other hand, the feeder 30 which controls the viscosity of the molten glass 2 through the throat 13a is connected downstream of the lance 13. Dissolved glass (2) dissolved in the melter (11) of the glass melting furnace (10) passes through the refiner (12), bubbles, foreign glass layers, and the like are removed and supplied to the dust (13), and in the dust (13) The viscosity of the molten glass 2 is maintained at about 10 ⁴ Pa.s. After the plunger 14 is lifted, the molten glass 2 is supplied from the balance 13 to the feeder 30 through the throat 13a, and then taken out through an orifice 31 of the feeder 30. do.

As shown in FIGS. 2 to 4, the orifice 31 of the feeder 30 is formed in a three-stage stepped structure in which the first to third inner diameters 31a to 31c are gradually narrowed from the upper side to the lower side. have. And the feeder 30 is provided with a heater 32 surrounding the feeder 30 by heating means for adjusting the temperature of the feeder 30 to adjust the viscosity of the molten glass 2. Heater 32 maintains the viscosity of the molten glass (2) about ^7.6 Pa · s to ~10 ⁵ 10 controls the temperature of the feeder (30).

In addition, the manufacturing apparatus of the present invention is mounted to the orifice 31 of the feeder 30 and forming a molten glass 2 drawn out through the orifice 31 into a glass tube 3 (Forming die: 40) and An extrusion die 50 is provided. The forming die 40 has a rim 41 which is fitted to the first inner diameter 31a of the orifice 31, and is arranged in the center of the rim 41 to substantially guide the flow of the molten glass 2 to the tubular shape. The rim 41 and the mandrel 42 are formed so as to form a flow path 43 of the molten glass 2 between the mandrel 42 and the rim 41 and the mandrel 42 having an inverted vertebrae head shape. It consists of a plurality of connecting rods 44 that connect radially.

As shown in detail in FIG. 2, the mandrel 42 is disposed at the second and third inner diameters 31b, 31c of the orifice 31 and has a taper portion having a diameter gradually narrowing from the upper side to the lower side ( 42a) and the straight pipe part 42b which extends directly below and below the taper part 42a, and has the same diameter. Between the second and third inner diameters 31b and 31c of the orifice 31 and the taper portion 42a of the mandrel 42, a flow passage 45 is formed in which the cross-sectional area gradually decreases toward the straight pipe portion 42b. The extrusion die 50 has an extrusion hole 51 continuous to the third inner diameter 31c so as to limit the outer diameter of the molten glass 2 passing through the third inner diameter 31c of the orifice 31. A straight pipe portion 42b of the mandrel 42 enters the upper side of the hole 51 to form a flow path 52 between the straight pipe portion 42b and the extrusion hole 51. The outer diameter of the glass tube 3 finally passing through the extrusion hole 51 is determined by the inner diameter of the extrusion hole 51.

1 and 5, the manufacturing apparatus of the present invention includes a pair of drawing devices 60 for drawing to draw the glass tube 3 drawn out through the orifice 31 of the feeder 30, The drawing device 60 is provided on both sides directly below the orifice 31. The drawing device 60 rotates the capstan rollers 61 with a plurality of flexible capstan rollers 61 arranged on both sides of the glass tube 3 in the conveying direction so as to contact the outer surface of the glass tube 3. It consists of a servo motor 62 for providing a driving force to be made, and a transmission mechanism 63 for transmitting the driving force of the servo motor 62 to the capstan rollers 61. The transmission mechanism 63 includes a driven sprocket 63a mounted on the drive shaft 62a of the servomotor 62, driven sprockets 63b mounted on each of the capstan rollers 61, and a driven sprocket 63a. ) And a chain 63c wound around the driven sprockets 63b. In the present embodiment, any one of the drawing devices 60 of the pair of drawing devices 60 may constitute the capstan roller 61 in a non-driven manner. And the spacing between the capstan rollers 61 is fastened so as to be screwed along the lead screw is rotated by the operation of the handle well known by the gap adjusting mechanism consisting of a screw fixed to the drawing device (60). I can regulate it.

Referring again to FIG. 1, a laser interference measuring device 70 is installed between the extrusion die 50 and the drawing device 50 as an outer diameter measuring means for measuring the outer diameter of the glass tube 3. The laser interference measuring device 70 receives a laser beam transmitter 71 for transmitting a laser beam, and a laser beam receiver 72 for receiving the laser beam transmitted from the laser beam transmitter 71 and calculating an outer diameter value of the glass tube 3. It consists of). The laser beam receiver 72 of the laser interference measuring device 70 is interfaced to the controller 80, and the controller 80 processes the outer diameter value of the glass tube 3 input from the laser beam receiver 72 to generate a hydraulic cylinder ( 15) the operation of the heater 32 and the servomotor 62 is controlled. And downstream of the drawing device 60, the cutting device 90 which cuts into the required length of the glass tube 3 which passes the drawing device 60 is provided.

Now, a method of manufacturing a glass tube by the apparatus for producing a glass tube according to the present invention having such a configuration will be described with reference to FIG. 6.

Referring to FIG. 1, first, the glass raw material 1, which is suitably prepared to manufacture the required glass tube 3 through the dog house 11a of the melter 11, is introduced into the melter 11 to be dissolved (S100). . For example, the glass raw material of the glass tube for cold cathode fluorescent lamp is SiO ₆ 67.7%, B ₂ O ₃ 18.5%, Al ₂ O ₃ 3.8%, Li ₂ O 0.9%, Na ₂ O 0.9%, K It may be composed of 7.6% by weight ₂ O, 0.3% by weight ZrO _2, 0.3% by weight CeO ₂ . In the melter 11 of the glass melting furnace 10, the temperature is raised to a temperature suitable for melting the glass raw material 1 by means of heating such as a gas burner during initial operation. When the initial glass raw material 1 is dissolved, the glass raw material 1 is dissolved by the operation of the electric boosting device 16. In the melter 11, the injected glass raw material 1 is dissolved at about 1,550 ° C. for about 48 hours.

Next, the molten glass 2 dissolved in the melter 11 of the glass melting furnace 10 flows to the refiner 12 through the throat 11b, and is then passed through the throat 12a of the refiner 12. It is supplied to the earth 13 (S102). In the refiner (12) and the ground (13), the molten glass (2) is melted by the operation of the electric boosting device (16) and the upper layer of the molten glass (2) through the duct (21) of the air supply device (20). Conditioning of the molten glass 2 is performed simultaneously by supplying cooling air. In the refiner 12, the molten glass 2 is homogenized thermally, chemically and physically at about 1,300 ° C. to remove bubbles, foreign glass layers, and the like. In the ground 13, the molten glass 2 is homogenized and homogenized at about 1,100 degreeC, and the viscosity of the molten glass 2 is maintained at about 10 <^4> Pa * s. At this time, the throat 13a of the balance 13 is closed by the plunger 14.

On the other hand, when the throat 13a of the mux 13 is opened by the lifting and lowering of the plunger 14, the molten glass 2 of the mux 13 is supplied to the feeder 30 through the throat 13a. (S104). By operating the heater 32, the temperature of the feeder 30 is controlled to about 700 to 1,000 ° C., preferably about 850 ° C. to maintain the viscosity of the molten glass 2 at about 10 ⁵ to 10 ^7.6 Pa · s (S106). ). If the viscosity of the molten glass (2) 10 ⁵ Pa · s less than while the glass tube (3) is a drawing as it passes through the extrusion hole 51 in the extrusion die 50 is recessed inward, and the dimensional defects, 10 ^7.6 Pa · When larger than s, the drawing itself of the molten glass 2 becomes difficult. The inner diameter and the outer diameter of the glass tube 3 can be adjusted by the temperature of the molten glass 2, the outer diameter and the drawing speed of the straight tube portion 42b, and the like.

Subsequently, as shown in FIG. 2, the molten glass 2 whose viscosity is adjusted in the feeder 30 is passed through the flow path 43 of the forming die 40 through the second and third inner diameters of the orifice 31. The flow passage 45 formed between the tapered portions 42a of the forming die 40 and 31b and 31c is sequentially passed, and at this time, the flow rate of the molten glass 2 is reduced step by step. The molten glass 2 is drawn while passing through the flow path 52 formed between the straight pipe part 42b of the forming die 40 and the extrusion hole 51 of the extrusion die 50, and is formed into the glass tube 3. (S108). In this embodiment, the inner diameter of the extrusion hole 51 can be maintained at about 1-25 mm, and the space | interval between the straight pipe part 42b and the extrusion hole 51 can be maintained at about 0.1-1.2 mm. Therefore, according to the manufacturing method of the present invention, the glass tube 3 having a diameter of about 1 to 25 mm and a thickness of about 0.1 to 1.2 mm can be manufactured without excluding the blowing of air which has been conventionally performed by the Danner method and the bellow method. In particular, by adjusting the outer diameter of the straight pipe portion 42b, the inner diameter of the extrusion hole 51, and the drawing speed, the outer diameter of about 1 to 5 mm, thickness of about 0.1 to 0.6 mm, outer diameter and thickness deviation ± 0.02 mm or less precision A glass tube can be manufactured efficiently.

In addition, as shown in FIG. 1, the glass tube 3 passing through the extrusion hole 51 of the extrusion die 50 is naturally cooled and cured while being exposed to the atmosphere (S110). The laser beam transmitter 71 of the laser interference measuring device 70 transmits a laser beam to the glass tube 3, and the laser beam receiver 72 receives a laser beam passing through the glass tube 3 to receive the glass tube 3. The outer diameter is measured and the outer diameter value is input to the controller 80 (S112). The controller 80 processes the outer diameter value input from the laser beam receiver 72 of the laser interference measuring device 70 by a program to control the operation of the plunger 14, the heater 32, and the servomotor 62. The flow rate, the drawing speed, and the like of the molten glass 2 are controlled to satisfy the dimensions of the glass tube 3 (114).

As shown in FIG. 5, the glass tube 3 cured through the extrusion hole 51 of the extrusion die 50 is interposed between the capstan rollers 61 of the drawing device 60, and the capstan roller 61. ) When the servomotor 62 of the drawing device 60 is driven, the driving force of the servomotor 62 is driven by the capstan roller (the sprocket 63a, the driven sprocket 63b, and the chain 63c of the transmission mechanism 63). The capstan roller 61 which is transmitted to 61 and rotates accordingly pulls the glass tube 3 directly downward to keep the continuous drawing of the glass tube 3 smoothly (S116). By the drawing of such a drawing apparatus 60, the narrow glass tube 3 whose bending degree with respect to 1.5 m in length is 0.2 mm or less can be manufactured precisely. In addition, the drawing speed of the glass tube 3 by the drawing device 60, that is, the feeding speed of the glass tube 3 is maintained at 30 m / min so that the narrow diameter glass tube 3 of the outer diameter 2.6 ± 0.02 mm, thickness 0.3 ± 0.01 mm (3) ), Such narrow glass tube (3) is suitable as a glass tube for cold cathode fluorescent lamps. Finally, the glass tube 3 past the drawing device 60 is cut to the required length by the cutting device 90 (S118).

On the other hand, in order to determine the difference between the glass tube of Examples 1 to 8 manufactured by the manufacturing apparatus and method of the present invention and the glass tube of Comparative Examples 1 to 4 manufactured by the conventional Danner method (mm) ), Outer diameter deviation (mm), thickness (mm), thickness deviation (mm) and warpage occurrence were measured and shown in Table 1. Glass tubes of Examples 1 to 8 and Comparative Examples 1 to 4 were made of glass raw materials having the same composition. The outer diameter and outer diameter deviation of the glass tube were measured by a micrometer, and the thickness and thickness deviation were measured by an optical microscope. And it was judged whether or not the bending of the glass tube rolled straight by rolling a 1.5m long glass tube on a 2m x 1.5m flat plate inclined at a 15 degree angle.

division Outer diameter Outer diameter deviation thickness Thickness deviation Whether warping occurs Example 1 2.6 ± 0.02 0.3 ± 0.01 X Example 2 2.4 ± 0.02 0.2 ± 0.01 X Example 3 3.0 ± 0.02 0.4 ± 0.01 X Example 4 4.5 ± 0.02 0.5 ± 0.01 X Example 5 5.0 ± 0.02 0.6 ± 0.01 X Example 6 2.0 ± 0.02 0.2 ± 0.01 X Example 7 1.5 ± 0.02 0.2 ± 0.01 X Example 8 1.0 ± 0.02 0.1 ± 0.01 X Comparative Example 1 7.0 ± 0.05 0.7 ± 0.05 X Comparative Example 2 5.0 ± 0.05 0.6 ± 0.05 X Comparative Example 3 3.0 ± 0.05 0.5 ± 0.05 O Comparative Example 4 2.6 ± 0.05 0.3 ± 0.05 O

As can be seen from Table 1, the glass tubes of Examples 1 to 8 manufactured by the manufacturing apparatus and method of the present invention have an outer diameter of 1 to 5 mm, an outer diameter deviation of ± 0.02 mm, a thickness of 0.1 to 0.6 mm, and a thickness deviation of ± It was shown that it has a precision of 0.01 mm and no warping phenomenon occurred. As described above, it has been proved that the thin-film glass tube satisfying the specification of the cold cathode fluorescent lamp can be accurately and efficiently produced by the manufacturing apparatus and method of the present invention.

Although the warpage did not occur in the glass tubes of Comparative Example 1 and Comparative Example 2 manufactured by the conventional singlet method, it was found that the outer diameter, the outer diameter deviation, the thickness and the thickness deviation were large, and thus were unsuitable for the manufacture of cold cathode fluorescent lamps. . Although the glass tubes of Comparative Example 3 and Comparative Example 4 had good outer diameters and thicknesses, the outer diameter and thickness variations were large, and it was found that the glass tubes of the glass tubes of the comparative examples 3 were unsuitable for the production of cold cathode fluorescent lamps due to warpage.

On the other hand, in the manufacturing apparatus of the present invention when manufacturing a narrow glass tube having an outer diameter of 1 to 5mm, it can be efficiently produced by maintaining the molding amount of the glass tube to 80% or more relative to the amount of the dissolution of the glass melting furnace (10). In addition, the glass tube can be sufficiently manufactured even with a small capacity of about 500 to 1,000 kg, which is about 1/100 smaller than that of the glass melting furnace applied to the conventional Danner method. Therefore, the cost of the glass melting furnace 10 can be greatly reduced, and the amount of energy required for the operation of the glass melting furnace 10 can be minimized to greatly reduce the manufacturing cost of the glass tube.

The embodiments described above are merely to describe preferred embodiments of the present invention, the scope of the present invention is not limited to the described embodiments, those skilled in the art within the spirit and claims of the present invention It will be understood that various changes, modifications, or substitutions may be made thereto, and such embodiments are to be understood as being within the scope of the present invention.

As described above, according to the apparatus and method for manufacturing a glass tube according to the present invention, the glass tube is formed by a drawing apparatus while the glass tube is formed through a stepped orifice, a forming die and an extrusion die after maintaining an optimum viscosity suitable for forming the glass tube. By controlling the drawing speed, the narrow glass tube can be manufactured precisely and efficiently, and the yield can be greatly improved by appropriately and efficiently maintaining a quantitative balance between the amount of dissolution into the glass melt and the amount of glass tube molded. In addition, the size of the glass tube can be easily changed by the forming die, the extrusion die, and the control of the drawing speed, and in particular, the fine glass tube of good quality without the warping phenomenon suitable for the production of the cold cathode fluorescent lamp without blowing the air can be produced. It can be effective.

Claims (6)

A feeder having a stepped orifice connected downstream of the glass melting furnace for dissolving the glass raw material into the molten glass, the cross-sectional area being gradually reduced toward the downstream to draw the molten glass downward; Heating means surrounding the feeder to control the temperature of the feeder to adjust the viscosity of the molten glass; A forming die mounted to an orifice of the feeder, the forming die having a mandrel capable of tubularly inducing a flow of the molten glass drawn through the orifice of the feeder; An extrusion die mounted to be continuous with the forming die and determining an outer diameter of the molten glass passing through an orifice of the feeder; Apparatus for producing a glass tube comprising drawing means for drawing the glass tube passing through the extrusion die. 2. The mandrel of claim 1 wherein the mandrel of the forming die is disposed in the center of a rim that is fitted to an orifice of the feeder and is connected by a plurality of connecting rods that are radial to the rim, wherein the mandrel is gradually from top to bottom. The manufacturing apparatus of the glass tube which consists of a taper part which has a narrowing diameter, and a straight pipe part extended directly under the taper part. The method of claim 1, wherein the drawing means, A plurality of capstan rollers having flexibility arranged at both sides of the glass tube in a conveying direction so as to be in contact with an outer surface of the glass tube; A servo motor providing a driving force for rotating the capstan rollers; Apparatus for manufacturing a glass tube composed of a transmission mechanism for transmitting the driving force of the servo motor to the capstan rollers. The drawing means according to claim 1 or 3, further comprising: a laser interference measuring device provided between the feeder and the drawing means to measure the outer diameter of the glass tube, and the drawing means by processing the outer diameter value of the glass tube input from the laser interference measuring device. Apparatus for manufacturing a glass tube further comprising a controller for controlling the operation of the. Dissolving the glass raw material into the molten glass in the glass melting furnace and feeding the downstream feeder; Controlling the temperature of the feeder to adjust the viscosity of the molten glass; Tubularly shaping the molten glass through a stepped orifice, a forming die and an extrusion die of the feeder; A method for producing a glass tube comprising the step of drawing the glass tube to be cured through the extrusion die directly below. The method for producing a glass tube according to claim 5, wherein the viscosity of the molten glass in the feeder is maintained at about 10 ⁵ to 10 ^7.6 Pa · s.