Manufacturing equipment and method for medium borosilicate glass tubes for medicine

Abstract

The present invention relates to an apparatus and method for manufacturing medium borosilicate pharmaceutical glass tubes. The manufacturing apparatus of the present invention includes a melting system, a forming system, and a cutting system. The forming system includes a muffle furnace (10), a forming furnace (11), and an annealing furnace (18) arranged vertically from top to bottom. An annular gap is provided between the trough (12) in the muffle furnace and the guide tube (23) and the inner wall of the furnace body flow path. The glass liquid is propelled downward by gravity and the pressing force of the annular gap and enters the forming furnace. The tube tensioning system includes traction rollers (16) and guide clamp rings (17) to clamp and position the glass tube (20). The traction rollers (16) clamp the glass melt, and the glass melt is continuously pulled by the combined action of its own gravity and the rotational force of the traction rollers (16) to form a glass tube.

Description

[Technical Field]

[0001] The present invention relates to the technical field of manufacturing pharmaceutical glass tubes, and more particularly to an apparatus and method for manufacturing medium borosilicate pharmaceutical glass tubes. [Background technology]

[0002] As the direct carrier of pharmaceuticals, pharmaceutical packaging materials play an important role in ensuring the quality and safety of pharmaceuticals. Glass, with its smoothness, transparency, easy disinfection, and good sealing properties, has proven itself as the preferred packaging material in the pharmaceutical industry after nearly a century of application and practice. Medium borosilicate glass, in particular, boasts superior impact resistance and chemical stability, making it internationally recognized as the safest pharmaceutical packaging material. It is widely used in packaging high-grade infusions, antibiotics, lyophilized formulations, vaccines, biological products, and other pharmaceuticals.

[0003] The production of borosilicate glass for pharmaceutical applications is entirely carried out through secondary processing of borosilicate glass tubes, and the drawing technology for borosilicate tubes is the core of the bottles made from borosilicate tubes. Currently, the main methods for producing borosilicate tubes are the Danner and Virot processes. The Virot process requires tall factory buildings and requires large investments and energy consumption. The Danner process is more widely used, but the lifespan of the rotating tubes used in the Danner process limits the efficiency of drawing, and regular replacement and maintenance substantially increase production consumption. Summary of the Invention [Problem to be solved by the invention]

[0004] The pulling equipment used in the manufacturing process of pharmaceutical glass tubes requires frequent replacement of consumables and regular maintenance. [Means for solving the problem]

[0005] SUMMARY OF THE INVENTION In order to solve the above problems, the present invention provides an apparatus and method for manufacturing medium borosilicate pharmaceutical glass tubes.

[0006] In order to achieve the above object, the present invention employs the following technical techniques. The present invention includes a melting system, a forming system, and a cutting system, The melting system includes a melting zone and a fining zone arranged in this order. The melting zone is used to melt the ingredients to form a glass liquid, which is then transferred to the fining zone. The fining zone is used to generate bubbles in the glass liquid to homogenize it and remove the bubbles by stirring. The glass liquid is transferred to the trough (12) of the forming system through a supply pipe (9). The forming system includes a muffle furnace (10), a forming furnace (11), and a furnace (12) arranged vertically from top to bottom. The muffle furnace (10) includes a trough (12), the trough (12) has an inverted truncated cone shape, a guide tube (23) is provided below the trough (12), the guide tube (23) extends from the muffle furnace (10) to the lower end of the forming furnace (11), a furnace body flow path (13) is provided outside the muffle furnace (10) and the guide tube (23), and the furnace body flow path (13) is connected to the trough (12) and and a guide tube (23) arranged coaxially with the guide tube (23) and forming an annular gap; the forming furnace (11) is provided with a plurality of sets of traction rollers (16) and a plurality of guide clamp rings (17) used to clamp and position the glass tube (20); the traction rollers (16) are installed on the clamp transmission mechanism support (22), and the clamp transmission mechanism support (22) and the guide clamp ring (17) are installed on the furnace wall of the forming furnace (11) and connected to an external servo motor; similarly, a plurality of sets of traction rollers (16) and a plurality of guide clamp rings (17) are installed on the upper part of the annealing furnace (18); and the cutting system is installed below the forming system and is used to cut the glass tube (20) after forming and annealing to a specific size depending on its application.

[0007] Furthermore, the apparatus further includes an online detection system (19), which is disposed at the outlet of the annealing furnace (18) and is used to monitor and provide feedback on the diameter and condition of the glass tube in real time.

[0008] Furthermore, the side of the traction roller (16) has a curved surface of revolution, and a plurality of the traction rollers (16) are installed as a set at the same horizontal height in the forming furnace (11), and the generatrix of the curved surfaces of the traction rollers (16) forms a ring to encase the glass tube (20).

[0009] Furthermore, heating devices (14) are provided outside the upper parts of the muffle furnace (10), the forming furnace (11), and the annealing furnace (18), temperature measuring devices (15) are provided outside the muffle furnace (10) and the forming furnace (11), and a temperature measuring device (15) is provided on the outer side of the annealing furnace (18) according to the temperature gradient inside the furnace.

[0010] Furthermore, the depth of the inner body of the trough (12) is equal to or greater than half the total height of the trough (12) and is equal to or less than the total height of the trough (12).

[0011] Furthermore, positioning rings (21) are fixedly installed on both ends of the traction roller (16).

[0012] Furthermore, the minimum diameter of the furnace body flow path (13) is 2 to 30 mm larger than the bottom diameter of the trough (12).

[0013] The melting zone further includes a melting furnace (1), which has a flue (2) at the top of its front wall, a supply port (3) at the bottom of its front wall, heating electrodes (4) arranged in layers on the pool wall side, combustors (5) on both sides of the breastwork of the melting furnace (1), and an exhaust port at the bottom of the melting furnace (1).

[0014] The clarification zone further includes a clarification channel and a homogenization tank (6), the clarification channel connecting the melting furnace (1) and the homogenization tank (6), the homogenization tank (6) being provided with an agitator (7), a bottom bubbling device (8), and a discharge port, the bottom bubbling device (8) generating bubbles in the glass liquid to promote clarification of the glass liquid, the agitator (7) homogenizing the glass liquid, and the discharge port being provided at the bottom of the homogenization tank (6).

[0015] In addition, in the manufacturing method using the above-mentioned apparatus for manufacturing medium borosilicate glass tubes, the compounding material is melted in a melting furnace (1) at a high temperature until the melt viscosity of the glass liquid reaches 10 2 -10 2.3 After melting, the glass is transferred to a homogenization tank (6), and the viscosity after the glass fining and homogenization is 10 2.5 -10 3 a step of fining the glass, removing bubbles, and homogenizing the glass so that the viscosity becomes dPa·s; a step of moving the glass to a muffle furnace (10) through a supply pipe (9), and waiting until the glass liquid fills a trough (12); when the glass liquid fills the trough (12), the glass liquid overflows from the circular top of the trough (12) and flows down uniformly along the outer edge of the trough (12) through an annular gap formed between a furnace body flow path (13) and the trough (12); The diameter of the glass tube (20) gradually decreases along the outside of the trough (12), and the diameter of the glass liquid also gradually decreases. Then, the glass tube (20) enters the forming furnace (11), where it is clamped by a plurality of sets of traction rollers (16) and a plurality of guide clamp rings (17) of the tube tensioning system. The uniform tension force of the traction rollers (16) and the weight of the glass itself pull the glass along the tube tensioning system, forming the hollow, elongated glass tube (20) with a uniform thickness until the viscosity of the glass tube reaches 10 4 -10 4.3 forming the glass tube (20) into a glass having a viscosity of 10 dPa·s; 9The method includes the steps of annealing the glass tube (20) in an annealing furnace (18) at a pressure of dPa·s or higher to remove stress, and then transferring the annealed glass tube (20) to a cutting device, where it is cut to a predetermined size, inspected, and packaged. [Effects of the Invention]

[0016] The present invention has the following beneficial effects. In the apparatus for manufacturing medium borosilicate pharmaceutical glass tubes provided by the present invention, the glass liquid is propelled downward through the annular gap between the trough in the muffle furnace and the conduit and the inner wall of the furnace body flow path by gravity and the pressure of the annular gap, and then enters the shaping furnace. The tube pulling system is equipped with traction rollers and guide clamping rings to clamp and position the glass tube, and the glass melt is continuously drawn out by the combined action of gravity and the rotational force of the traction rollers to form a glass tube. The overall manufacturing process is simple, avoiding complex processes while ensuring the internal and external quality of the glass tube. The manufacturing apparatus of the present invention has a simple structure and is easy to maintain, further reducing costs and energy consumption.

[0017] Furthermore, the manufacturing equipment of the present invention is equipped with a fining channel for primary fining, and a foaming device in the fining / homogenization tank for secondary fining. The two-stage fining process further accelerates the fining of the glass liquid. The traction roller has a curved, rotating side that forms a ring to clamp the glass melt, ensuring that the glass melt receives a uniform traction force and ensures the uniform thickness of the produced glass tube.

[0018] In order to more clearly describe the technical solutions of the embodiments of the present invention, the drawings that need to be used in the embodiments are briefly introduced below. [Brief explanation of the drawings]

[0019] [Figure 1] 1 is a structural schematic diagram of a medium borosilicate pharmaceutical glass tube manufacturing apparatus according to the present invention; [Figure 2]1 is a structural schematic diagram of a traction roller in a tube tensioning system of the device according to the present invention; FIG. [Figure 3] 1 is a schematic view of the installation of traction rollers in the tube tensioning system of the device according to the invention; FIG. [Figure 4] 1 is a schematic diagram of the arrangement of traction rollers in the tube tensioning system of the device according to the invention; FIG. [Figure 5] 1 is a structural schematic diagram of a guide clamping ring in a tube tensioning system of the device according to the present invention; FIG. DETAILED DESCRIPTION OF THE INVENTION

[0020] In order to facilitate those skilled in the art in understanding the technical solutions of the present invention, the following clearly and completely describes the technical techniques of the embodiments of the present invention with reference to the drawings in the embodiments of the present invention. It is clear that the described embodiments are only some embodiments of the present invention, and are not all embodiments. Based on the embodiments of the present invention, all other embodiments that can be obtained by those skilled in the art without creative work also fall within the protection scope of the present invention.

[0021] It should be noted that the terms "first," "second," and the like in the present specification and claims, as well as in the drawings, are used to distinguish between similar objects and do not imply a particular order or context. It should be understood that, where appropriate, these terms are interchangeable and that embodiments of the present invention may be performed in an order other than that described or illustrated herein. Furthermore, the terms "comprising" and "having" and variations thereof are intended to be non-exclusive inclusive; for example, a process, method, system, product, or apparatus that includes multiple steps or elements may include other steps or elements not expressly listed or that are inherent to the process, method, product, or apparatus.

[0022] The present invention will be described in more detail below with reference to the drawings.

[0023] As shown in FIG. 1, the apparatus for manufacturing medium borosilicate pharmaceutical glass tubes according to the present invention includes a melting system, a forming system and a cutting system.

[0024] The melting system melts and delivers glass, which includes high-temperature melting of raw materials, removing bubbles by stirring, and homogenizing by bubbling. The melting system is horizontally positioned and includes a melting zone, a fining zone, and a delivery pipe 9, arranged in that order.

[0025] The melting zone is used to melt the batch materials into a glass liquid. It includes a melting furnace 1, which is equipped with a flue 2, a feed port 3, heating electrodes 4, a combustor 5, and an exhaust port. The flue 2 is located at the top of the front wall of the melting furnace 1, and the feed port 3 is located at the bottom of the front wall. The heating electrodes 4 are made of molybdenum or tin oxide and are stacked on the pool wall (side stack type). Combustors 5 are located on both sides of the breast wall of the melting furnace 1. An exhaust port is located at the bottom of the melting furnace 1, through which materials are discharged to remove impurities that have precipitated in the glass liquid. The melting furnace 1 is heated by either an electric or electric gas heating system to heat the materials.

[0026] The fining zone includes a fining channel and a homogenization vessel 6, which is equipped with an agitator 7, a bottom bubbling device 8, and a discharge port. The fining channel connects the melting furnace 1 and the homogenization vessel 6. The bottom bubbling device 8 generates bubbles in the glass liquid to promote convection and clarification of the glass liquid. The agitator 7 is used to homogenize the glass liquid. The discharge port is installed at the bottom of the homogenization vessel 6 and is used to intermittently discharge materials and remove impurities that have precipitated in the glass liquid.

[0027] The supply pipe 9 is used to transport the molten glass liquid to the trough 12 of the forming system, and one end of the supply pipe 9 communicates with the flow passage at the bottom side of the fining zone, and the other end is located above the trough 12.

[0028] The blend, consisting of a combination of ground glass powder and powdered materials, is fed into the melting furnace 1 through the feed port 3 and melted at high temperature into a melt. After complete melting, it passes through the fining channel and enters the fining zone. The clarified and homogenized glass liquid flows through the feed pipe 9 into the trough 12 of the forming system.

[0029] The forming system includes a muffle furnace 10, a forming furnace 11 and an annealing furnace 18 arranged vertically from top to bottom.

[0030] The muffle furnace 10 includes a trough 12, a furnace body flow passage 13, and the upper portion of a guide tube 23. The trough 12 is shaped like an inverted truncated cone, and the depth of the inner cylinder of the trough 12 is greater than half the total height of the trough 12 but less than the total height of the trough 12. The guide tube 23 is cylindrical and installed below the trough 12. The guide tube 23 extends from the muffle furnace 10 to the lower end of the forming furnace 11, and the bottom of the trough 12 and the upper end of the guide tube 23 are connected via a circular arc. The opening diameter of the furnace body flow passage 13 is larger than the cross-sectional diameter of the trough 12, and the furnace body flow passage 13 is installed coaxially with the trough 12 and the guide tube 23. This forms an annular gap between the inner wall of the furnace body flow passage 13 and the trough 12 and the guide tube 23 in the muffle furnace 10. The diameter of the annular gap gradually decreases from top to bottom and remains constant below the guide tube 23. The minimum diameter of the furnace body flow path 13 is 2 to 30 mm larger than the bottom diameter of the trough 12 .

[0031] As shown in Figures 1 to 5, the forming furnace 11 is equipped with a tube tensioning system, which includes a traction roller 16, a guide clamp ring 17, a clamp transmission mechanism bracket 22, and the lower part of a guide tube 23. The clamp transmission mechanism bracket 22 is installed on the wall of the forming furnace 11, and the traction roller 16 is installed on the clamp transmission mechanism bracket 22, and the traction roller 16 is rotatable on the clamp transmission mechanism bracket 22. Positioning wheels 21 are installed on both ends of the traction roller 16 to prevent the traction roller 16 from moving horizontally on the clamp transmission mechanism bracket 22. The clamp transmission mechanism bracket 22 is connected to a servo motor, which controls the traction roller 16 on the clamp transmission mechanism bracket 22 to rotate on its axis in the glass flow direction. The side of the traction roller 16 is a rotating curved surface. A group of multiple traction rollers 16 is installed at the same height within the forming furnace 11, and the generatrix of the rotating curved surfaces of the multiple traction rollers 16 forms a ring that wraps around the glass tube 20. A plurality of sets of traction rollers 16 clamp and hold the glass melt, and the glass melt is continuously pulled under the combined action of its own gravity and the rotational force of the traction rollers 16 to form a glass tube 20. A guide clamp ring 17 is installed on the wall of the forming furnace 11 and connected to an external servo motor, which can be moved according to the actual process needs. A plurality of guide clamp rings 17 are installed alternately with the traction rollers 16 and play the role of guiding and positioning the glass melt during the stretching process.

[0032] In one embodiment of the present invention, a set of four traction rollers 16 forms a ring that wraps around the glass tube 20 .

[0033] Similarly, a plurality of sets of traction rollers 16 and guide clamp rings 17 are installed inside the annealing furnace 18, and are concentrated in the upper part of the annealing furnace 18.

[0034] As shown in Figure 1, heating devices 14 are evenly spaced around the outside of the muffle furnace 10 and the forming furnace 11. These heating devices 14 are used to heat and maintain the furnace body temperature. Heating devices 14 are also concentrated at the top of the annealing furnace 18, where they are set to gradually decrease the temperature inside the annealing furnace 18. This aims to relieve stress inside the glass and tighten the internal structure of the glass tube 20 stretched and formed by the tube tensioning system. The heating devices 14 are heating rods or heating wires wrapped around the outer wall of the furnace body. Temperature measuring devices 15 are evenly spaced around the outside of the muffle furnace 10 and the forming furnace 11, and another temperature measuring device 15 is placed outside the annealing furnace 18 according to the temperature gradient inside the furnace. The temperature measuring device 15 is a thermocouple.

[0035] An online detection system 19 is installed at the outlet of the annealing furnace 18 to provide real-time monitoring and feedback of the glass tube diameter and glass tube condition.

[0036] The cutting system is installed below the forming system and is used to cut the formed and annealed glass tubes 20 to a specific length depending on the intended use. The cut ends are rounded with a round mouthpiece frame or smoothed by polishing. The cut glass tubes 20 are stacked and packed.

[0037] The following describes in detail a method for producing medium borosilicate pharmaceutical glass tubes using the above-mentioned apparatus, which includes the following steps:

[0038] The ingredients are weighed according to the mixing ratio, and then placed in a mixer and mixed uniformly.

[0039] The uniformly mixed ingredients are melted at high temperature in a melting furnace 1 to form glass. The melt viscosity of the glass liquid is 10 2 -10 2.3 dPa·s.

[0040] After melting, the glass is transferred to a homogenization tank 6, where it is clarified, bubbles are removed, and the glass is homogenized. After clarification and homogenization, the viscosity of the glass is 102.5 -10 3 dPa·s.

[0041] The glass is then transferred to the muffle furnace 10 through the supply pipe 9, and the trough 12 is left to fill with glass liquid. Once the glass liquid is filled in the trough 12, it simultaneously overflows from the circular top of the trough 12 and flows downward along the outer edge of the trough 12, through the annular gap formed between the furnace body flow path 13 and the trough 12, with a uniform thickness of glass liquid. The diameter of the glass tube 20 gradually decreases along the outside of the trough 12, and the diameter of the glass liquid also gradually decreases before entering the forming furnace 11. The glass melt is clamped by multiple sets of traction rollers 16 and multiple guide clamp rings 17 of the tube tensioning system, and is pulled along the tube tensioning system by the uniform tension force of the traction rollers 16 and the glass's own weight, forming a hollow, elongated glass tube 20 with a uniform thickness. The viscosity of the glass tube during formation is 10 4 -10 4.3 dPa·s.

[0042] Viscosity is 10 9 The material is then placed in an annealing furnace 18 at a pressure of dPa·s or higher to remove stress.

[0043] After annealing, the glass tubes are moved to a cutting machine to be cut to the preset dimensions, inspected, and packaged. After inspection, they are sent to the secondary processing stage to be finished into pharmaceutical glass bottles such as ampoules and syringes.

[0044] The above examples are intended to illustrate the technical problems of the present invention, and are not intended to limit the present invention. Although the present invention has been described in detail based on the above examples, those skilled in the art can modify or equivalently replace the specific embodiments of the present invention. As long as these modifications or equivalent replacements do not deviate from the spirit and scope of the present invention, they are included in the scope of protection of the claims of the present invention. [Explanation of symbols]

[0045] 1. Blast furnace 2 Flue 3 Supply port 4 Heating electrode 5. Combustor 6. Equalization pond 7 Stirring device 8 Bottom Bubbling Device 9 Supply pipe 10 Muffle furnace 11 Molding furnace 12 Trough 13. Furnace body flow path 14 Heating device 15 Temperature measuring device 16 Traction roller 17 Guide clamp ring 18 Annealing furnace 19 Online detection equipment 20 Glass tube 21 Traction roller positioning wheel 22 Clamp transmission mechanism bracket 23 Guide tube

Claims

1. Includes a melting system, a forming system, and a cutting system, The melting system includes a melting zone and a fining zone arranged in sequence, the melting zone is used to melt the ingredients into a glass liquid and transfer it to the fining zone, the fining zone is used to generate bubbles in the glass liquid to homogenize it and remove bubbles by stirring, and the glass liquid is transferred to the trough (12) of the forming system through a supply pipe (9); The forming system includes a muffle furnace (10), a forming furnace (11), and an annealing furnace (18) arranged vertically from top to bottom, the muffle furnace (10) including a trough (12), the trough (12) having an inverted truncated cone shape, a guide tube (23) provided below the trough (12), the guide tube (23) extending from the muffle furnace (10) to the lower end of the forming furnace (11), a furnace body flow path (13) provided outside the muffle furnace (10) and the guide tube (23), the furnace body flow path (13) being arranged coaxially with the trough (12) and the guide tube (23) and being annular. a plurality of sets of traction rollers (16) and a plurality of guide clamp rings (17) are provided in the forming furnace (11) to clamp and position the glass tube (20); the traction rollers (16) are installed on the clamp transmission mechanism support (22); the clamp transmission mechanism support (22) and the guide clamp ring (17) are installed on the furnace wall of the forming furnace (11) and connected to an external servo motor; and a plurality of sets of traction rollers (16) and a plurality of guide clamp rings (17) are also provided on the upper part of the annealing furnace (18); The cutting system is located below the forming system and is used to cut the glass tube (20) that has completed forming and annealing into a specific size according to its intended use.

2. further comprising an online detection system (19); 2. The medium borosilicate pharmaceutical glass tube according to claim 1, wherein the online detection system (19) is disposed at the outlet of the annealing furnace (18) and is used for monitoring and feedback of the diameter and condition of the glass tube in real time.

3. 2. The medium borosilicate glass tube for medicine according to claim 1, wherein the traction roller (16) has a side surface with a curved surface of revolution, a plurality of the traction rollers (16) are installed as a set at the same horizontal height in the forming furnace (11), and the generatrix of the curved surfaces of the traction rollers (16) forms a ring to enclose the glass tube (20).

4. A heating device (14) is provided on the outside of the upper portion of the muffle furnace (10), the forming furnace (11), and the annealing furnace (18); A temperature measuring device (15) is provided outside the muffle furnace (10) and the forming furnace (11), 2. The medium borosilicate glass tube for medicine according to claim 1, wherein a temperature measuring device (15) is provided on the outer side of the annealing furnace (18) in accordance with the temperature gradient inside the furnace.

5. 2. The medium borosilicate pharmaceutical glass tube according to claim 1, wherein the depth of the inner body of the trough (12) is equal to or greater than half the total height of the trough (12) and is equal to or less than the total height of the trough (12).

6. 2. The medium borosilicate glass tube for medicine according to claim 1, wherein positioning rings (21) are fixedly installed on both ends of the traction roller (16).

7. 2. The medium borosilicate glass tube for medicine according to claim 1, wherein the minimum diameter of the furnace body flow passage (13) is 2 to 30 mm larger than the bottom diameter of the trough (12).

8. The melting zone comprises a melting furnace (1), 2. The medium borosilicate medicinal glass tube according to claim 1, wherein the melting furnace has a flue (2) at the top of its front wall, a supply port (3) at the bottom of its front wall, the heating electrodes (4) arranged in a stacked manner on the pool wall side, combustors (5) on both sides of the battlement wall of the melting furnace, and an exhaust port at the bottom of the melting furnace.

9. the clarification zone comprises a clarification channel and a homogenization vessel (6); The fining channel connects the melting furnace (1) and the homogenization tank (6), and the homogenization tank (6) is provided with a stirrer (7), a bottom bubbling device (8), and a discharge port; 2. The medium borosilicate medicinal glass tube according to claim 1, wherein the bottom bubbling device (8) generates bubbles in the glass liquid to promote clarification of the glass liquid, the stirring device (7) homogenizes the glass liquid, and the discharging port is provided at the bottom of the homogenization tank (6).

10. A manufacturing method using the manufacturing apparatus for medium borosilicate glass tubes for medicine according to any one of claims 1 to 9, The blending material is melted in a melting furnace (1) at a high temperature until the melt viscosity of the glass liquid reaches 10 ２ -10 ２．３ Melting the glass to a viscosity of dPa s; After melting, the mixture is transferred to a homogenization tank (6), and the viscosity after glass fining and homogenization is 10 ２．５ -10 ３ fining, debubbling and homogenizing the glass to a viscosity of 1000 dPa s; The glass is then transferred to a muffle furnace (10) through a supply pipe (9), and the trough (12) is filled with the glass liquid. When the glass liquid is filled in the trough (12), it simultaneously overflows from the circular top of the trough (12) and flows downward along the outer edge of the trough (12) through the annular gap formed between the furnace body flow path (13) and the trough (12), with the thickness of the glass liquid flowing downward uniformly. The diameter of the glass tube (20) gradually decreases along the outside of the trough (12), and the diameter of the glass liquid also gradually decreases. The glass then enters a forming furnace (11), where the glass melt is clamped by a plurality of sets of traction rollers (16) and a plurality of guide clamp rings (17) of a tube tensioning system. The uniform tension force of the traction rollers (16) and the weight of the glass are used to pull the glass along the tube tensioning system, forming a hollow, elongated glass tube (20) with a uniform thickness until the viscosity of the glass tube at the time of forming is 10. ４ -10 ４．３ forming the material to have a viscosity of dPa s; The glass tube (20) is ９ annealing the structure in an annealing furnace (18) at a pressure of 500 dPa·s or more to remove stress; and transferring the annealed glass tube (20) to a cutting device, where it is cut according to a preset size, inspected, and packaged.

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