Method and apparatus for manufacturing glass tube having closed end

Abstract

Methods and apparatus are provided for manufacturing a glass tube having a closed end, including providing a glass tube having an open end, closing a first open end while introducing a gas into the tube through a second open end, opening a vent hole in a wall of the glass tube proximate one of the ends, and closing the second open end.

Description

Technical Field

[0001] The invention relates to a method and a device for sealing glass tubes in the heat-softened state, in particular for sealing glass tubes for producing primary packaging means made of glass for storing pharmaceutical active substances. Background Art

[0002] In the production of glass tubes, the glass tubes are usually cut from a glass tube production line produced by, for example, the Vero or Danner process and are then further processed. These glass tubes can have a standard length, for example, 1.5 meters, but can also be cut to other lengths and thus directly processed into primary packaging means for storing drug substances, such as glass ampoules, glass vials, glass cartridges or glass syringes. For these applications, it is preferred that no impurities reach the interior of the glass tube during processing and handling, since these impurities can only be removed from the interior of the glass tube again with great effort. Therefore, the tube ends are cut off from the glass tubes directly in a special tube end processing machine in the heat-softened state and are used to seal the tubes during further processing or transportation in order to prevent particles from being deposited inside the glass tubes.

[0003] The glass tubes described above are preferred for further processing (e.g. production of primary packaging for pharmaceutical substances) because, due to being closed at both ends, the glass tubes are very strong and can withstand extensive handling without breaking. This is highly desirable for transport and further processing because losses due to accidental damage are greatly reduced.

[0004] These glass tubes have closed ends and a vent hole formed in the wall of the glass tube near one of the closed ends. The vent hole ensures that no problems will occur due to changes in gas pressure during transportation and storage. Summary of the invention

[0005] Methods for producing closed tubes are known in the art, for example from US 9458045 or EP 4023615. However, these known methods produce closed glass tubes which from time to time show contamination of the interior with residues, sometimes also referred to as snow, which can appear immediately after production but also sometimes days or weeks after production, for example during storage or transport. This contamination is disadvantageous for the further processing of the tubes and requires the tubes to be rejected for further processing or additional cleaning steps. It is therefore an object of the present invention to provide a method and a device for producing closed glass tubes which reliably produce contamination-free closed glass tubes. BRIEF DESCRIPTION OF THE DRAWINGS

[0006] The details of the present invention will be described below with reference to the accompanying drawings, in which:

[0007] Figures 1A to 1E The method steps according to the present invention are schematically shown.

[0008] Figure 2 An example of an embodiment of a gas supply mechanism is shown, and

[0009] Figure 3 Another example of the embodiment of the gas supply mechanism is shown. DETAILED DESCRIPTION

[0010] Reference Figures 1A to 1E A process of manufacturing a glass tube according to the first embodiment is shown. Figure 1A A glass tube 10 is shown, which has a length L, with a first end 30 and a second end 20 located at the distal end of the tube 10. The glass tube 10 has a circumferential wall and encloses an interior space. In this example, the length L is about 1.5 meters, but other lengths are possible. The length is preferably 0.5 to 2.0 meters, because such a length has the advantage of being convenient for transportation and convenient for further processing.

[0011] The purpose is to close both ends 20 , 30 of the tube 10 and to provide a vent hole 32 in the wall of the glass tube 10 , wherein the vent hole is close to one of the ends 20 , 30 .

[0012] In the first step, if Figure 1B As shown, the first end 30 is closed using a closing tool 50. In the process of closing the first end, a gas F is blown into the second end 20 of the glass tube by a gas supply mechanism 60. The gas F is blown into the tube 10 in the axial direction of the tube 10 in the direction toward the second end 20, so that the gas F enters the internal space of the tube 10 and preferably fills the internal space of the tube 10. In a variation of this step, the start point of blowing the gas F into the second end 20 begins before the first end 30 is closed. Once the first end 30 is completely closed, the gas supply mechanism 60 is stopped. The first end 30 is now closed. Figure 1B Indicated as 31. In a variation of this step, the gas supply mechanism may be stopped before the first end is completely closed.

[0013] In the second step, if Figure 1C As shown, a vent hole 32 is formed in the wall of the glass tube near the second end 20 of the glass tube 10 by an opening tool 70. During this step, the gas supply mechanism 60 may be stopped. In an optional variation, the gas supply mechanism 60 may remain in operation and stop once the vent hole 32 has been formed, or stop during the process of forming the vent hole 32.

[0014] In the third step, if Figure 1DAs shown, the second end 20 of the glass tube 10 is also closed using a closing tool 55, for example, which is of the same type as the closing tool 50 used to close the first end 30 of the glass tube. The second end of the tube 10 that is now closed is indicated by 21. Preferably, after the second step is completed, the third step is completed within a short period of time. This short period of time can be, for example, 5 to 15 seconds.

[0015] After the third step, the result is that both ends 21, 31 of the glass tube 10 are closed, and a vent hole 32 is provided near one of the ends 21. Figure 1E As described above, by supplying the gas F into the tube 10 during the process of closing the first end portion 30, the resulting closed tube 10 will not be internally contaminated even after long-term storage.

[0016] Methods and devices for sealing the ends of glass tubes as described above are known in the art as closing tools for closing the ends of glass tubes, for example as described in US10315946. Generally speaking, the end to be closed is heated (for example, using a gas burner) so that the glass softens, and the end is closed using a forming tool so as to physically form the closed end, or the now softened end is allowed to fall freely due to gravity, thereby closing the end of the glass tube. In these types of closing methods, the glass tube can be rotated around its circumferential axis to improve the closing process. According to the present invention, any suitable closing method or device can be used.

[0017] The vent hole is applied by an opening tool 70, which is known in the art and uses a spot burner. Preferably, the burner is located above the glass tube when the hole is opened, but it can be located at other locations. The location of the vent hole is preferably close to the closed end of the glass tube, because the section of the tube between the vent hole and the nearest closed end of the glass tube cannot usually be further processed.

[0018] The gas F used is preferably a non-reactive gas that does not interfere with the end-capping process or the surface of the glass tube. An example is air, which has a relative humidity of 5%-20% at room temperature of 20°C. The absolute humidity of the air is preferably between 0.05 and 5 g / m 3Other examples may also be nitrogen, carbon dioxide or mixtures thereof, also with low relative humidity (water vapor content). Other non-reactive engineering gases (such as noble gases such as argon) may also be used, preferably with a water content (i.e., humidity) in the range of 5%-20% at room temperature of 20°C. Gases that are reactive in the sense of combining with water may also be used, since the use of these gases also reduces the humidity of the gas. Blowing the gas into the glass tube during processing results in a significant reduction or complete elimination of internal contamination of the closed tube. Preferably, the gas is filtered to prevent unwanted particles from entering the glass tube to be closed. Gas filtering methods are known in the art, for example, by physical filters.

[0019] exist Figure 2 An example of an embodiment of a gas supply mechanism 601 according to the present invention is shown in FIG. In this embodiment, the gas supply mechanism 601 is provided with an inlet 602 connected to a gas source 603, which provides gas under pressure. For example, this can be done using a gas compressor. The gas source 603 can be provided with a gas pressure regulator, which regulates the pressure of the gas to be supplied and regulates an opening and closing mechanism that can open and close the gas source. Such gas sources are known in the art. The gas source may also include a flow meter.

[0020] The inlet 602 is connected to the outlet 604, where the gas F leaves the gas supply mechanism 601 and enters the open end of the glass tube. Figure 2 In the illustrated embodiment, the gas supply mechanism includes a nozzle 605. An outlet 604 of the nozzle 605 is arranged so that the gas F discharged from the outlet 604 of the nozzle 605 can enter the tube end 20 of the tube 10. Preferably, the nozzle 605 is aligned with the axial direction of the tube 10. The outlet 604 of the nozzle 605 is arranged at a certain distance from the tube end 20 so that the gas F can freely enter the glass tube 10.

[0021] exist Figure 3In the embodiment shown, the gas supply mechanism 701 includes an outlet 704 that discharges the gas F into a distribution chamber 707. The distribution chamber 707 is preferably formed as a cylindrical chamber with an open end 709 at the end away from the outlet 704, the outlet 704 being located at or near the center of the chamber 707 at the closed end of the chamber. The open end 709 of the distribution chamber 707 is arranged close to or around the end 20 of the glass tube 10 so that the gas F leaving the outlet 704 and collected in the distribution chamber 707 can freely enter the glass tube 10. Around the open end 709 of the distribution chamber 707, a circumferential protective shield 708 can be arranged. During the supply of the gas F to the glass tube 10, the protective shield 708 extends around the end section 20 of the tube 10. The protective shield 708 forms a chamber that keeps the gas F in an overpressure state (compared to the ambient air pressure), thereby preventing the ambient air from entering the glass tube 10, or at least reducing the amount of ambient air entering. The diameter of the circumference of the shield 708 is preferably greater than the diameter of the open end 709 of the distribution chamber 707. The shield 708 need not be continuous around the circumference and may be provided with additional openings to change the gas flow, thereby improving the flow of the gas F to facilitate its entry into the glass tube 10.

[0022] The present invention can also be implemented by adding the air supply mechanism according to the present invention to an existing closure device. In this case, the air supply mechanism should be added to the existing device so that the air supply mechanism is aligned with the end of the tube at the point where the end will be closed.

Claims

1. A method for producing a glass tube having closed ends, the method comprising the following steps: providing a glass tube (19) having open ends (20, 30), closing the first open end (30) while introducing a gas (F) into the tube (10) through the second open end (20), A vent hole (32) in the wall of the glass tube (10) adjacent to one of the open ends (20) is opened, and the second open end (21) is closed.

2. The method according to claim 1, wherein the introduced gas (F) has a relative humidity of 5% to 20%.

3. A method according to any one of the preceding claims, wherein the gas (F) is introduced through a distribution chamber (707) located near the second open end.

4. The method according to claim 3, wherein the distribution chamber (707) is positioned axially with respect to the glass tube (10).

5. The method according to claim 3 or 4, wherein the distribution chamber (707) is formed by a gas outlet and a three-sided open chamber surrounding at least a part of the second open end.

6. The method according to claim 1 or 2, wherein the gas (F) is introduced through a nozzle (605) located near the second open end.

7. The method according to any one of the preceding claims, wherein the gas (F) is air.

8. A closed glass tube manufactured using the method according to any one of the preceding claims.

9. A device for sealing a glass tube, comprising: A glass tube transport mechanism for transporting glass tubes, First closing tool, Vent Tool, a second closing tool, and An air supply mechanism is provided, wherein the air supply mechanism is arranged opposite to the first closing tool.

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