Small-batch glass mechanical drawing glass tube device and use method thereof

Abstract

The invention discloses a device for mechanically drawing glass tubes from small-batch glass and a using method thereof. Belongs to the technical field of glass production. The device mainly solves the problems of low forming precision and poor internal quality of domestic small-batch mechanically-drawn glass tubes. The device is mainly characterized by comprising a melting device, a heating device, a clarifying device, a cooling and homogenizing device and a glass tube drawing device. Raw materials are melted, heated, clarified, cooled and homogenized to flow into the material basin, uniformly flow downwards on the periphery of the overflow disc, are subjected to temperature compensation through the material basin pipe, the material bowl and the columnar heating module, and flow out from the end of the blowing rod and a gap of the material bowl for pipe drawing. The method has the advantages that small-batch pipes are continuously and mechanically drawn, and the discharge amount is 200-500L / d; the internal quality of the product reaches the level of optical glass; the forming precision is high, and the roundness and straightness are smaller than 0.3 mm; the consistency is good, and the inner and outer diameter deviation and the thickness deviation are smaller than 0.3 mm; formula replacement can be quickly realized, and other small-batch glass tubes can be produced.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of glass production and manufacturing, in particular to a small-batch glass tube precise drawing device and a use method thereof. BACKGROUND

[0002] The domestic methods for drawing daily-use glass tubes include the Danne method, the Vello method, the vertical upward drawing method, and the vertical downward drawing method. The Danne method and the Vello method belong to horizontal drawing methods, and are used to draw glass tubes with an inner diameter of 30 mm and a wall thickness of 3.5 mm. However, the forming precision is low, and it is difficult to achieve an inner diameter and wall thickness deviation of 0.3 mm. The melting furnace is made of refractory bricks, and the erosion of special components is large, so it is not suitable for small-batch production. In addition, the output per day needs to be more than 10 tons to obtain high-quality glass tubes. The vertical upward drawing method and the vertical downward drawing method belong to vertical drawing methods. When the glass liquid flows from the liquid channel to the bowl, the glass liquid flow inlet of the bowl and the opposite viscosity difference cannot be avoided. The flow rate of the bowl mouth is unstable, and this phenomenon is more obvious when the output is small. There is no successful case of small-batch mechanical tube drawing in the domestic and foreign literature. At present, small-batch high-precision glass tubes mainly rely on imports from abroad.

[0003] At present, the glass tube melting furnace for small-batch and multi-variety production mainly adopts the eight trigrams furnace melting method, and uses clay crucibles as the glass melting carrier. In addition, the glass cannot be stirred during the melting process, which leads to poor consistency of the prepared small-batch glass components and performance, and a large number of bubbles, impurities, and obvious stripes. The glass is formed by artificial picking and blowing. During the blowing process, multiple people are needed to cooperate. The glass is formed by multiple rolling and drawing processes. In addition, it is difficult to determine the position of the qualified tube, which leads to low size control precision of the formed tube, low production efficiency, and low yield. The production efficiency is low, and the quality is unstable.

[0004] The existing patent technology includes: patent document 1: CN202210894760.6 discloses a glass tube preparation device and its use method, which can be used for small-batch tube drawing production, but is only suitable for drawing thin-walled tubes. In addition, the device uses refractory material as the crucible, which has a large erosion of lead and bismuth components. The intermittent production has no stirring device, and the internal quality cannot be guaranteed.

[0005] Patent document 2: CN202222484881.1 discloses a glass bottle production equipment technology field, and a glass tube drawing forming device. The device has no clarification and homogenization part, and cannot produce high-quality glass products.

[0006] Patent document 3: CN201910423959.9 discloses a glass skin for optical fiber image transmission elements and a mechanical tube drawing forming method thereof. The glass has excellent chemical properties, stable glass composition, low refractive index, and excellent anti-crystallization performance. However, the melting furnace cannot switch the formula, and is not suitable for small-batch production. SUMMARY

[0007] The present application is to break through the deficiencies of the prior art, provide a small batch glass tube drawing device and method.

[0008] The technical solution of the drawing device is: a small batch glass mechanical drawing glass tube device, characterized by: comprising a melting device, a heating device, a clarifying device, a cooling and homogenizing device and a glass tube drawing device connected in sequence; the melting device is composed of a melting outer bucket, a melting inner bucket and an air pipe, the melting inner bucket and the melting outer bucket are supported and positioned by an H-shaped support, the bottom of the melting inner bucket is provided with an inner bucket liquid outlet, and the side bottom of the melting outer bucket is provided with an outer bucket liquid outlet; the heating device is composed of a heating tank connected by a faucet pipe; the clarifying device is composed of a clarifying tank; the cooling and homogenizing device is composed of a cooling bucket and a stirrer connected by a cooling bucket communication pipe; the glass tube drawing device is composed of a material basin connected by a material basin communication pipe, a blowing rod located in the material basin, a laser diameter measuring instrument located below the lower port of the material basin, a roll tube drawing machine and a glass tube lower breaking mechanism; the lower port of the material basin is provided with a columnar heating module.

[0009] The material basin in the technical solution of the drawing device comprises a shell composed of a material basin feeding pipe, a material basin pipe and a material bowl connected in sequence, and comprises an overflow tray located at the upper part of the material basin feeding pipe, the overflow tray is provided with overflow tray electrode sheet one and overflow tray electrode sheet two, and direct current heating is adopted to maintain the required temperature; the material basin pipe is provided with a material basin pipe electrode sheet and a material bowl electrode sheet; the material bowl is matched with the blowing rod and is provided with a material basin pipe electrode sheet.

[0010] The overflow tray electrode sheet one, the overflow tray electrode sheet two and the material basin communication pipe in the technical solution of the drawing device are uniformly distributed in the circumferential direction of the material basin, that is, the adjacent two are separated by 120°.

[0011] The melting device in the technical solution of the drawing device further comprises a melting bucket feeding pipe connected with the bottom of the melting outer bucket; the melting inner bucket and the melting outer bucket are both made of zirconium dispersed reinforced platinum; the position of the outer bucket liquid outlet connected with the faucet pipe at the side bottom of the melting outer bucket is not higher than 1 / 5 of the height of the melting inner bucket, so as to prevent the un-melted glass liquid from taking a shortcut.

[0012] The material basin feeding pipe in the technical solution of the drawing device is divided into two parts, and is connected by a corundum gasket; the overflow tray is welded with the upper half of the material basin as a whole; the diameter A of the overflow tray opening of the overflow tray and the diameter B of the material basin feeding pipe meet the following relationship: A / B=0.3~0.6; the difference C between the diameter of the material bowl opening and the diameter of the blowing rod and the distance H from the material bowl opening to the highest liquid level in the material basin meet the following relationship: 0.1

[0013] In the technical solution of the drawing device of the present invention, the highest point of the faucet tube is provided with a faucet exhaust hole; the clarification tank is provided with a front exhaust hole and a rear exhaust hole; the bottom of the heating tank and the clarification tank have a certain inclination angle; and the bottom of the cooling crucible is provided with a cooling crucible discharge pipe.

[0014] The technical solution of the drawing device of the present invention describes a roller tube drawing machine with heating modules and insulation plates around its perimeter; the melting device uses silicon molybdenum rods and silicon carbide rods for heating, and uses temperature control instruments, power supply, and multiple sets of platinum-rhodium wire thermocouples to control and monitor the temperature of the space and platinum; there is a step between the material basin discharge pipe and the material basin pipe for fixing.

[0015] The technical solution of the present invention is: a method for using a small-batch mechanical glass drawing device for glass tubes, characterized by including the following steps: (a) Adjust the temperature control of the melting device, heating device, clarifying device, cooling device, and glass tube drawing device to the operating temperature; (b) Glass powder / cooked material is added into the melting inner crucible at certain time intervals through a scoop. The atmosphere is adjusted and the material is fully melted using a vent pipe. The material flows through a tap pipe to the heating tank for heating. After clarification in the clarification tank, the material flows to the cooling crucible. A stirrer is used to homogenize the glass liquid. (c) The molten glass flows into the material basin, and the temperatures of the material basin tube, the platinum heating of the material bowl, the columnar heating module and the overflow plate are set; (d) The molten glass flows down from the gap between the blower end and the material bowl. After removing the waste material from the inlet, the glass tube is guided onto the roller drawing machine. A counterweight is added to slowly reduce the speed of the drawing machine. When the glass tube size is close to the target, the laser diameter measuring instrument is turned on for automatic tube drawing control. The tube is cut at the lower glass tube cutting mechanism.

[0016] In step (c) of the technical solution of the method of the present invention, the temperature of the overflow plate is set to 1100-1300℃ and the temperature of the columnar heating module is set to 800-1200℃; in step (d), the tube drawing speed of the roller tube drawing machine is 400-1000 mm / min (0.4-1 m / min).

[0017] In step (a) of the technical solution of the method of the present invention, the temperature of the melting device is raised to 1350°C, the temperature of the heating device is raised to 1430°C, the temperature of the clarifying device is raised to 1480°C, the temperature of the cooling device is raised to 1200°C, and the temperature of the glass tube drawing device is raised to 1150°C; in step (b), glass powder / cooked material is added into the melting inner crucible (1a) at a rate of 4.2 kg / 10 min through a material spoon, oxygen is introduced through the vent pipe at a rate of 1.5 L / min, and the stirrer homogenizes the glass liquid at a rate of 15 rpm / min; in step (c), the overflow plate temperature is 1250°C, the platinum heating of the material basin tube is 1130°C, the platinum heating of the material bowl is 995°C, the columnar heating module is 1100°C, A / B=0.5, C / H=0.15; and the tube drawing speed is maintained at 486 mm / min.

[0018] The beneficial effects of this invention are: the preparation process is simple, the continuous mechanical tube drawing products have good consistency; the debugging period is short when changing the formula or re-extracting the furnace, the production efficiency is high, and the formula can be changed quickly; this furnace type adopts a combination of platinum electric heating and modular heating, which effectively improves the forming accuracy; the output is 200-500L / d; and this furnace type can produce various small batches of glass tubes with high internal quality and long furnace service life.

[0019] Advantages of this invention: continuous mechanical drawing of small batches of tubes with a output of 200-500L / d; product internal quality reaches optical glass level; high forming precision, roundness and straightness <0.3mm; good consistency, inner and outer diameter deviation and thickness deviation <0.3mm; and the ability to quickly change the formula to produce other small batches of glass tubes.

[0020] This invention is mainly used for the precise drawing of small batches of glass tubes. Attached Figure Description

[0021] Fig. 1 This is a schematic diagram of the device of the present invention.

[0022] Fig. 2 This is a perspective view of the feed basin device of the present invention.

[0023] Fig. 3 This is a top view of the feed basin device of the present invention.

[0024] Fig. 4 This is a cross-sectional view of the feed basin device of the present invention.

[0025] Icons: 1-Melting outer crucible, 1a-Melting inner crucible, 2-Vent pipe, 3-Dial pipe, 3a-Dial vent, 4-Heating tank, 4a-Material inlet, 5-Settling tank, 5a-Front vent of settling tank, 5b-Rear vent of settling tank, 6-Cooling crucible connecting pipe, 7-Stirrer, 8-Cooling crucible, 9-Material basin connecting pipe, 10-Air blower, 11-Material basin, 12-Overflow plate, 12a-Overflow plate electrode 1. Electrode plate 12b- Overflow plate 2, 13- Material basin discharge pipe, 14- Material basin pipe, 14a- Material basin pipe electrode plate, 14b- Material bowl stacked electrode plate, 15- Material bowl, 15a- Material basin pipe electrode plate, 16- Columnar heating module, 17- Laser diameter gauge, 18- Roller tube drawing machine, 19- Glass tube lowering mechanism, 20- Cooling crucible discharge pipe, 21- Melting crucible discharge pipe, 22- Corundum gasket ring. Detailed Implementation

[0026] like Figs. 1 to 4 The apparatus shown comprises a melting device, a heating device, a refining device, a cooling and homogenizing device, and a glass tube drawing device. Heating utilizes a combination of silicon molybdenum rods and silicon carbide rods. Temperature control employs a temperature controller, a power supply, and multiple sets of platinum-rhodium wires as thermocouples to control and monitor the space and platinum. Since radiant heating is a well-established method in the melting industry, it will not be elaborated upon here. The platinum material is supported and fixed externally using refractory materials, and the furnace is surrounded by refractory insulation material.

[0027] Open the furnace door and continuously push the raw material horizontally above the inner melting crucible 1a using a scoop, then rotate and pour it into the crucible. Melting takes place in the inner melting crucible 1a; the molten glass flows from the bottom holes into the interlayer between the inner melting crucible 1a and the outer melting crucible 1, flowing backwards. The inner and outer melting crucibles are preferably zirconium-reinforced platinum crucibles, primarily to prevent platinum corrosion and glass coloring for small batches of glass with special components. During melting, the vent pipe 2 is used to adjust the furnace atmosphere and enhance the melting effect. A melting crucible discharge pipe 21 is located at the bottom, allowing the molten glass in the melting crucible to be completely drained when changing the formula or during intermittent production.

[0028] After the molten glass melts, it flows through the faucet pipe 3 to the receiving port 4a. The highest point of the faucet pipe 3 is designed with a vent hole 3a, primarily to prevent siphoning and to release air. The molten glass flows into the heating tank 4 for rapid heating. The main purpose of this is to prevent the molten glass from flowing directly into the refining tank 5, where the temperature cannot be raised enough to remove air bubbles. After heating, the molten glass flows into the refining tank 5, where the vent holes 5a at the front and 5b at the back of the refining tank release the gas. The bottoms of the heating tank 4 and the refining tank 5 have a certain angle of inclination.

[0029] The clarified molten glass flows into the cooling crucible 8 through the cooling crucible connecting pipe 6. Under the stirring of the stirrer 7, the molten glass is cooled and homogenized, which is more effective than the homogenization in the cooling tank and saves space. A cooling crucible discharge pipe 20 is provided at the bottom, which can drain the molten glass from the heating tank 4, the clarifying tank 5, and the cooling crucible 8 when the formula is changed or production is interrupted.

[0030] After homogenization, the molten glass flows into the trough 11 through the trough connecting pipe 9 and accumulates in the overflow plate 12. The overflow plate 12 is electrically heated by electrode plates 12a and 12b, causing the molten glass to spread evenly and overflow into the trough. This process ensures consistency in viscosity between the trough connecting pipe 9 and the opposite direction of the molten glass. As the molten glass flows evenly into the trough through the overflow plate holes, its viscosity increases while maintaining minimal viscosity around the edges. A trough discharge pipe 13 is installed above the overflow plate 12 and at the tail of the trough 11 to discharge molten glass and handle emergency overflows. The trough is divided into two parts, separated by a 22mm corundum gasket, allowing for segmented maintenance of the platinum structure and preventing interference from the platinum electric heating. A step between the trough discharge pipe 13 and the trough pipe 14 provides a fixing function. The molten glass flows vertically downwards in the feed bowl 14 and feed cup 15. There is a temperature difference between the central molten glass and the surrounding molten glass. When the flow rate of the molten glass is low, prolonged production can cause problems such as crystallization and streaks. To address this, electrode plates 14a (feed bowl), 14b (feed cup), and 15a (feed bowl electrode plate) are designed to directly electrically heat the feed bowl 14 and feed cup 15, compensating for heat loss. The molten glass forms a downward-flowing glass tube between the blower 10 and the opening of the feed cup 15. A columnar heating module 16 is installed on the outer end of the tube to effectively solve the problem of glass tube diameter fluctuation.

[0031] The molten glass flows below the end, and waste material is cut off using shears. The glass tube is then guided onto the roller drawing machine 18. The speed of the drawing machine is adjusted according to the production dimensions. When the diameter approaches the target size, the laser diameter gauge 17 is linked with the roller drawing machine 18 to automatically adjust the size. Since the drawing process involves small quantities of glass, the roller drawing machine 18 should also include heating modules and insulation plates around its perimeter to prevent the glass tube from tempering or the material temperature from becoming too low. Finally, the glass tube is cut to the target length by the glass tube cutting mechanism 19.

[0032] Example 1: A method for using a small-batch glass tube drawing device includes the following steps: (a) Before production, the temperature control of the melting device is raised to 1350°C, the temperature control of the heating device is raised to 1430°C, the temperature control of the clarifying device is raised to 1480°C, the temperature control of the cooling device is raised to 1200°C, and the temperature control of the glass tube drawing device is raised to 1150°C.

[0033] (b) The glass molten material is added to the melting crucible at a rate of 4.2 kg / 10 min using a scoop, and oxygen is introduced through the vent pipe 2 at a rate of 1.5 L / min. After the glass molten material in the melting crucible reaches the liquid level, it flows through the tap pipe 3 to the heating tank 4, the refining tank 5, and the cooling crucible 8. The glass molten material passes through the partition and connecting pipe, and is homogenized by stirring at a speed of 15 rpm / min.

[0034] (c) The diameter A of the overflow pan in the material basin and the diameter B of the material basin conform to the following relationship: A / B=0.5. The overflow pan temperature is 1250℃, and the overflow flows uniformly downward around the overflow port. The difference C between the diameter of the material bowl and the diameter of the blowing rod and the distance H from the opening of the material bowl to the highest liquid level in the material basin conform to the following relationship: C / H=0.15.

[0035] (d) The molten glass flows into the material basin 11, the material basin tube 14 is heated to 1130°C with platinum, the material bowl 15 is heated to 995°C with platinum, and the columnar heating module 16 is heated to 1100°C.

[0036] (e) After removing the waste material from the guide head, the glass tube is guided onto the roller drawing machine 18. The counterweight is added to slowly reduce the speed of the roller drawing machine 18. When the glass tube size is close to the target, the automatic drawing system is turned on, and the final drawing speed is maintained at 486 mm / min.

[0037] (f) The small batch of glass tubes obtained had an inner diameter of 30.5 mm, an inner diameter deviation of 0.2 mm, a wall thickness of 3.5 mm, and a wall thickness deviation of 0.1 mm.

[0038] Using the same equipment and different formulas, Example 2 and Example 3 were produced again, with the same target size. The specific data are shown in the table below.

[0039] Example Process Parameters and Test Performance The above are merely preferred embodiments of the present invention and do not limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A device for mechanically drawing glass tubes in small batches, characterized in that: It comprises a melting device, a heating device, a clarifying device, a cooling and homogenizing device, and a glass tube drawing device connected in sequence; the melting device consists of a melting outer crucible (1), a melting inner crucible (1a), and a vent pipe (2), with the melting inner crucible (1a) and the melting outer crucible (1) supported and positioned by an "H"-shaped support column, the bottom of the melting inner crucible (1a) having an inner crucible outlet, and the bottom side of the melting outer crucible (1) having an outer crucible outlet; the heating device consists of a heating tank (4) connected by a faucet pipe (3); the clarifying device... The device consists of a clarification tank (5); the cooling and homogenization device consists of a cooling crucible (8) and a stirrer (7) connected by a cooling crucible connecting pipe (6); the glass tube drawing device consists of a material basin (11) connected by a material basin connecting pipe (9), an air blowing rod (10) located in the material basin (11), a laser diameter measuring instrument (17) located below the lower port of the material basin (11), a roller tube drawing machine (18) and a glass tube lower cutting mechanism (19). A columnar heating module (16) is provided on the outside of the lower port of the material basin (11).

2. The device for small-batch mechanical glass drawing of glass tubes according to claim 1, characterized in that: The material basin (11) includes a shell consisting of a material basin discharge pipe (13), a material basin pipe (14), and a material bowl (15) connected in sequence. It includes an overflow plate (12) located above the material basin discharge pipe (13). The overflow plate (12) is provided with an overflow plate electrode plate one (12a) and an overflow plate electrode plate two (12b), which are directly heated by current to maintain the temperature required for the process. The material basin pipe (14) is provided with a material basin pipe electrode plate (14a) and a material bowl superimposed electrode plate (14b). The material bowl (15) cooperates with the air blowing rod (10) and is provided with a material basin pipe electrode plate (15a).

3. The device for small-batch mechanical glass drawing of glass tubes according to claim 2, characterized in that: The overflow plate electrode one (12a), overflow plate electrode two (12b) and the material basin connecting pipe (9) are evenly distributed radially around the circumference of the material basin (11), that is, adjacent ones are 120° apart.

4. A small-batch glass mechanical drawing device for glass tubes according to claim 1, 2 or 3, characterized in that: The melting device also includes a melting crucible discharge pipe (21), which is connected to the bottom of the outer melting crucible (1); the inner melting crucible (1a) and the outer melting crucible (1) are both made of zirconium-dispersion reinforced platinum; the position of the liquid outlet of the outer crucible connected to the bottom of the side of the outer melting crucible (1) and the faucet pipe (3) is not higher than 1 / 5 of the height of the inner melting crucible (1a).

5. A small-batch glass mechanical drawing device for glass tubes according to claim 2 or 3, characterized in that: The material container discharge pipe (13) is divided into upper and lower parts, which are connected by a corundum gasket (22); the overflow plate (12) is welded to the upper part of the material container (11); the overflow plate diameter A of the overflow plate (12) and the diameter B of the material container discharge pipe (13) meet the following relationship: A / B=0.3~0.6; the difference C between the diameter of the material bowl and the diameter of the blowing rod and the distance H from the opening of the material bowl to the highest liquid level in the material container meet the following relationship: 0.1<C / H<0.

2.

6. A small-batch glass mechanical drawing device for glass tubes according to claim 1, 2 or 3, characterized in that: The highest point of the faucet pipe (3) is provided with a faucet exhaust hole (3a); the clarification tank (5) is provided with a clarification tank front exhaust hole (5a) and a clarification tank rear exhaust hole (5b); the bottom of the heating tank (4) and the clarification tank (5) has a certain inclination angle; the bottom of the cooling crucible (8) is provided with a cooling crucible discharge pipe (20).

7. A small-batch glass mechanical drawing device for glass tubes according to claim 1, 2 or 3, characterized in that: The roller tube drawing machine (18) is equipped with heating modules and insulation plates around its perimeter; the melting device uses silicon molybdenum rods and silicon carbide rods for heating, and uses temperature control instruments, power supply, and multiple sets of platinum-rhodium wire thermocouples to control and monitor the temperature of the space and platinum; there is a step between the material basin discharge pipe (13) and the material basin pipe (14) for fixing.

8. A method of using the glass tube drawing device for small-batch glass mechanical drawing as described in claim 1, characterized in that: Includes the following steps: (a) Adjust the temperature control of the melting device, heating device, clarifying device, cooling device, and glass tube drawing device to the operating temperature; (b) Glass powder / cooked material is added into the melting inner crucible (1a) at certain time intervals through a material spoon. The atmosphere is adjusted and fully melted using a vent pipe (2). The material flows through a tap pipe (3) to the heating tank (4) for heating. After clarification in the clarification tank (5), the material flows to the cooling crucible (8). A stirrer (7) is used to homogenize the glass liquid. (c) The molten glass flows into the material basin (11), and the temperatures of the material basin tube (14), the material bowl (15) platinum heating, the columnar heating module (16) and the overflow plate (12) are set; (d) The molten glass flows down through the gap between the blower (10) and the cup (15). After removing the waste material from the inlet, the glass tube is guided onto the roller drawing machine (18). The speed of the drawing machine is slowly reduced by adding a counterweight. When the glass tube size is close to the target, the laser diameter measuring instrument (17) is turned on for automatic tube drawing control. The tube is cut at the glass tube cutting mechanism (19).

9. The method of using the small-batch glass mechanical drawing device for glass tubes according to claim 8, characterized in that: In step (c), the temperature of the overflow plate (12) is set to 1100-1300℃, and the temperature of the columnar heating module (16) is set to 800-1200℃; in step (d), the tube drawing speed of the roller tube drawing machine (18) is 400-1000 mm / min.

10. A method of using a small-batch mechanical glass drawing device for glass tubes according to claim 8 or 9, characterized in that: In step (a), the temperature of the melting device is raised to 1350°C, the temperature of the heating device is raised to 1430°C, the temperature of the clarifying device is raised to 1480°C, the temperature of the cooling device is raised to 1200°C, and the temperature of the glass tube drawing device is raised to 1150°C. In step (b), the glass powder / cooked material is added to the melting inner crucible (1a) at a rate of 4.2 kg / 10 min through the material spoon, oxygen is introduced through the vent pipe (2) at a rate of 1.5 L / min, and the stirrer (7) homogenizes the glass liquid at a rate of 15 rpm / min. In step (c), the overflow plate temperature is 1250°C, the platinum heating of the material basin tube is 1130°C, the platinum heating of the material bowl is 995°C, the columnar heating module is 1100°C, A / B=0.5, C / H=0.15, and the tube drawing speed is maintained at 486 mm / min.

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