A method for producing a high-precision multi-channel large-aperture glass capillary tube

Abstract

The application provides a production method of high-precision multi-channel large-aperture glass capillary, which comprises the following parts: the first part: manufacturing composite capillary: filling copper column and performing preliminary shaping, and processing the shape into a wedge shape; the second part: multi-hole capillary assembly: a plurality of manufactured composite capillaries are spliced and surrounded into a ring shape in a wedge shape, and are assembled into a glass outer sleeve pipe, and the middle is filled with a solid glass core rod to form an assembly of multi-hole capillary; the third part: high-temperature stretching: the both ends of the glass outer sleeve pipe are fixed and stretched to obtain a composite multi-hole capillary rod body; and the fourth part: annealing, hole forming and finishing: the unqualified areas at the both ends are cut off, the qualified middle part is taken to a set length, and is placed into an acidic corrosion solution to corrode the copper column in the capillary hole. The capillary prepared by the method has better uniformity of hole diameter and is not easy to break the wall between capillary holes.

Description

TECHNICAL FIELD

[0001] The present application relates to a multi-channel capillary production process, in particular, a high-precision multi-channel large-aperture glass capillary production method. BACKGROUND

[0002] In the tobacco instrument industry, due to the need for cigarette and filter rod detection, a standard rod with annular capillary holes arranged on the cross section of the columnar body is needed to calibrate the cigarette filter rod test bench. It usually has stable resistance, and the key is the realization of high-precision multi-hole structure.

[0003] The aperture is usually between 0.1-1.5mm, but since the industry-standard columnar body cross-sectional diameter is usually 8mm, the large-diameter capillary in the annular arrangement often makes the wall thickness between the annularly distributed capillary holes become thinner and thinner during the stretching process, causing the hole wall to deform or even break during processing, resulting in a high scrap rate.

[0004] In addition, during the traditional drawing process, the capillary hole becomes thinner, and the influence of tension and its own weight causes the distribution of the stretching process to be actually uneven, and the distribution uniformity of the hole size is poor, so that as a standard rod, the final product still has a large number of unqualified parameters, and the final selection of the product used as a standard rod is the best of the best, with extremely high cost. With the progress and development of testing technology, the requirement for aperture size is becoming more and more precise, and the traditional simple drawing method cannot meet the requirements.

[0005] In order to solve the above problems, people have been seeking an ideal technical solution. SUMMARY

[0006] The purpose of the present application is to overcome the shortcomings of the prior art, and to provide a high-precision multi-channel large-aperture glass capillary production method that improves the size precision control of the capillary and prevents the capillary wall from being too thin and easily deformed.

[0007] In order to achieve the above purpose, the technical scheme adopted by the present application is as follows: a high-precision multi-channel large-aperture glass capillary production method, comprising the following parts:

[0008] First part: manufacturing composite capillary:

[0009] The application relates to a method for manufacturing a composite capillary tube, which comprises the following steps: manufacturing a capillary glass sleeve embryo with an inner diameter of greater than or equal to 1.2 mm, an outer diameter of greater than or equal to 3 mm and a length of greater than or equal to 300 mm, one end of the capillary glass sleeve embryo being sealed, a copper column with a higher outer shape size precision than the required precision of the inner diameter of the capillary tube is filled into the inner hole of the capillary glass sleeve embryo, the diameter of the copper column is smaller than the inner diameter of the capillary glass sleeve embryo, the other end of the capillary glass sleeve embryo is connected to a pipeline which is connected to a ventilation device, and then the capillary glass sleeve embryo filled with the copper column is sent into a heating furnace and heated at a high temperature of 850 DEG C to 1200 DEG C; on one hand, a wedge-shaped die is used to shape the outer contour of the capillary glass sleeve embryo so that the cross section of the outer contour is wedge-shaped; on the other hand, inert gas is injected into the gap between the copper column and the capillary glass sleeve embryo by the ventilation device so as to maintain or expand the inner diameter to a set size, generally, the expanded inner diameter size is 0.1 mm to 0.3 mm, and the composite capillary tube is formed;

[0010] The second part is a porous capillary tube assembly:

[0011] A plurality of the manufactured composite capillary tubes are spliced and surrounded into a ring shape in a wedge-shaped side, and are arranged in a glass outer sleeve tube with an outer diameter of greater than or equal to 9 mm, a wall thickness of greater than or equal to 3.7 mm and a length of greater than or equal to 300 mm, one end of the glass outer sleeve tube is sealed, one end of the pipeline connected to the composite capillary tube is exposed outside the glass outer sleeve tube, and a corresponding solid glass core rod is filled between the ring-shaped arranged composite capillary tubes, so that an assembly body of the porous capillary tube is assembled;

[0012] The third part is high-temperature stretching:

[0013] The assembly body of the porous capillary tube is suspended and sent into a wire drawing heating furnace, after being heated to 1000 DEG C to 1200 DEG C, the two ends of the glass outer sleeve tube are fixed and drawn, inert gas is injected into each composite capillary tube by the ventilation device in a first time period of starting the drawing, the inert gas is supported by positive pressure and cooperates with the drawing deformation to eliminate the gap among the composite capillary tube, the glass outer sleeve tube and the solid glass core rod, in a second time period of starting the drawing, the ventilation device is used to form negative pressure by external air extraction, the inner diameter of the composite capillary tube is contracted and tightly attached to the surface of the copper column, and finally the composite porous capillary tube rod body with a length of greater than or equal to 350 mm and an outer diameter of 8 to 9.0 mm is stretched in the glass outer sleeve tube part;

[0014] The fourth part is annealing, pore forming and finishing:

[0015] Put into annealing box for annealing, after annealing, the temperature drops to normal temperature, because the thermal expansion coefficient of copper column is greater than the thermal expansion coefficient of glass, the shrinkage range of copper column in composite capillary is greater than the shrinkage range of glass, the gap appears again; At the same time, check the appearance, judge whether it is fully fused, then cut off the unqualified area at both ends, take the qualified part in the middle to the set length, put it into the acid etching solution, make the copper column in the capillary hole corrode, and get the finished product after cleaning.

[0016] According to the above, after the assembly of the porous capillary is completed, the other end of the glass sleeve tube is vacuumized and then fused to seal, so that the capillary glass sleeve tube, the composite capillary and the solid glass core rod are fused together.

[0017] According to the above, during the assembly of the porous capillary, the space formed in the middle region after the composite capillary with a wedge shape is combined is a polygon or a circle in cross section, and the cross section of the solid glass core rod is a polygon or a circle.

[0018] According to the above, the acid etching solution comprises nitric acid or hydrochloric acid.

[0019] According to the above, after the copper column is corroded and cleaned, a cleaning liquid containing hard micro powder is used to continuously flush the capillary hole for micro-shaping, so as to remove the glass burrs and micro-particles in the capillary hole.

[0020] According to the above, the number of the composite capillaries is 8-12.

[0021] According to the above, the copper column is a copper alloy or pure copper.

[0022] According to the above, the glass is a low-expansion hard glass such as high borosilicate glass.

[0023] The present application has the following advantages compared with the prior art:

[0024] 1. The embryo structure of the porous capillary is decomposed into a plurality of composite capillaries filled with copper columns, and then assembled with a glass sleeve tube and a solid glass core rod and stretched, on the one hand, the copper column is used as the support of the whole capillary embryo during the preforming of the composite capillary, on the other hand, the gap between the copper column and the capillary embryo is very uniform, and the uniformity of the distribution of the positive pressure airflow around the copper column is also better, forming a stable airflow layer, thereby ensuring the accuracy of the inner hole during the formation of the composite capillary in the first step.

[0025] 2. In the process of drawing fusion, the elimination of the assembly gap and fusion need to consume a certain amount of drawing time, in this process, the copper column still plays a supporting role in the whole porous capillary, and in the process of fusion, the expansion ability of the positive pressure gas outward can be used to resist the extrusion pressure from the outside to the inside caused by stretching, avoiding the influence of the stretching process on the inner diameter size.

[0026] 3. In the second stage of the drawing fusion process, the positive pressure is changed to negative pressure, and the capillary hole at high temperature deforms inward and shrinks tightly on the surface of the copper column. The copper column can ensure the basic precision of the capillary hole due to its high precision and limited deformation at this temperature, avoiding the deformation of the capillary hole caused by other factors such as gravity and uneven stretching force.

[0027] 4. Since the capillary is made by twice molding, the wall size of the capillary is controlled twice. The first time can ensure that the wall thickness of the subsequent drawing process is not damaged by controlling the wall thickness of the composite capillary, and the second time controls the deformation degree through the fusion process to ensure that the wall is balanced and not damaged. BRIEF DESCRIPTION OF DRAWINGS

[0028] Figure 1 is a structure diagram of the composite capillary in the present application.

[0029] Figure 2 is a structure diagram of the assembly of the porous capillary in the present application.

[0030] Figure 3 is a structure diagram of the porous capillary after drawing in the present application.

[0031] Figure 4 is a structure diagram of the porous capillary after removing the copper column.

[0032] In the figure: 1. Capillary glass sleeve blank; 2. Copper column; 3. Glass outer sleeve; 4. Composite capillary; 5. Solid glass core rod; 6. Capillary hole. DETAILED DESCRIPTION

[0033] The technical solutions of the present application will be further described in detail through specific embodiments.

[0034] A production method of a high-precision multi-channel large-aperture glass capillary, comprising the following parts:

[0035] First part: manufacturing a composite capillary:

[0036] As Figure 1As shown, a capillary glass sleeve blank 1 is manufactured. The capillary glass sleeve blank 1 has an inner diameter ≥ 1.2 mm, an outer diameter ≥ 3 mm, and a length ≥ 300 mm. One end of the capillary glass sleeve blank is closed. A copper pillar 2 with a dimensional accuracy higher than the required accuracy of the capillary tube's inner diameter is filled into the inner hole of the capillary glass sleeve blank. The material of the copper pillar 2 can be copper alloy or pure copper. The diameter of the copper pillar 2 is smaller than the inner diameter of the capillary glass sleeve blank. The other end of the capillary glass sleeve blank 1 is connected through a pipe. The material is then fed into a heating furnace and heated at a high temperature of ≥850-1200℃. On one hand, a wedge mold is used to shape the outer contour of the capillary glass sleeve blank, making the cross-section of the outer contour wedge-shaped. On the other hand, inert gas is injected into the gap between the copper column and the capillary glass sleeve blank using the ventilation device to maintain or expand the inner diameter to a set size. The expanded inner diameter is 0.1mm-0.3mm, forming a composite capillary 4. The expanded size is very limited to ensure accuracy.

[0037] Part Two: Assembly of Porous Capillaries

[0038] like Figure 2 As shown, several pre-manufactured composite capillaries 4 are joined together with wedge-shaped sides to form a ring. In this embodiment, the number is 8-12. They are inserted into a glass outer tube 3 with an outer diameter ≥9mm, a wall thickness ≥3.7mm, and a length ≥300mm. One end of the glass outer tube 3 is sealed, and a portion of the composite capillaries 4 is exposed. Solid glass core rods 5 of corresponding shapes are filled between the annular composite capillaries to assemble a porous capillary assembly. The cross-sectional shape of the solid glass core rod can be polygonal or circular to accommodate the cross-section of the space left in the middle. Then, the other end of the glass outer tube is melted and sealed, so that the capillary glass sleeve, composite capillaries, and solid glass core rods are fused together. It should be noted that the ventilation equipment and pipelines are not removed.

[0039] Part Three: High-Temperature Tensioning

[0040] like Figure 3 As shown, the porous capillary assembly is suspended and fed into a drawing furnace. After being heated to 1000℃-1200℃, the two ends of the glass outer tube are fixed and drawn. During the first time period of drawing, the ventilation device injects inert gas into each composite capillary. The positive pressure support of the inert gas and the drawing deformation work together to eliminate the gaps between the composite capillary, the glass outer tube and the solid glass core rod. During the second time period of drawing, the ventilation device draws air outward to form a negative pressure. The inner diameter of the composite capillary shrinks and adheres tightly to the surface of the copper column. Finally, it is drawn into a composite porous capillary rod with a glass outer tube length ≥350mm and an outer diameter of 8.0mm-9.0mm.

[0041] Part IV: annealing, pore forming and finishing:

[0042] As shown in Figure 4 the annealing box for annealing, after annealing, the temperature drops to room temperature, because the thermal expansion coefficient of copper column is greater than the thermal expansion coefficient of glass, the shrinkage of copper column in the composite capillary is greater than the shrinkage of glass, the gap appears again; At the same time, the appearance is checked to judge whether it is fully fused, then the unqualified area at both ends is cut off, the qualified part in the middle is taken to a certain length, put into acid etching solution, the copper column in the capillary hole is etched away, the acid etching solution includes nitric acid or hydrochloric acid, and the finished product is obtained after cleaning.

[0043] After the copper column is etched and cleaned, the capillary hole 6 is continuously flushed with a cleaning solution containing hard micro powder to perform micro shaping and remove the glass burr and micro particles in the capillary hole.

[0044] Finally, the product is tested, and in general, the size can be measured by using an image processing system. The geometric size precision of the glass tube produced by high-temperature precision drawing process generally includes the inner diameter, outer diameter, ovality, concentricity and other parameters of the pipe. The performance index of the glass tube is related to the production process and use requirements. The inner diameter size tolerance of the glass tube is generally required to be plus or minus 5 microns, and the ovality is less than 10 microns.

[0045] The standard method for stress testing is to package the glass tube in a device and place it in a high-low temperature test box for testing. This method is very time-consuming. The rapid detection method is to put the glass tube in a container at a temperature of 600 degrees Celsius, then quickly take it out and place it in normal temperature water. Repeat this process 3 times, if the glass tube does not break, it is a qualified product.

[0046] Example 1 This example can be a separate patent, which is not suitable here

[0047] The final cutting preparation of the ventilation rate standard rod length is 120mm, the diameter is 8mm, the cross section is ten-hole ring arrangement, the longitudinal direction is ten-hole parallel to each other, and the ring-shaped distribution hole is equal in diameter, the side hole is punched at a position of 10-12.5mm from the end surface on the same end surface, the side hole diameter is 0.6mm, and the ultraviolet laser drilling machine is used for drilling to ensure the quality.

[0048] In this embodiment, a plurality of ventilation rate standard rods with different inner hole diameters are taken as examples for detection, and tables 1-3 are the detection value change states with hole diameters.

[0049] Table 1 Ventilation rate value when the number of side holes of the rod body is 1

[0050]

[0051]

[0052] Table 2 Ventilation rate values when the number of holes on the side of the rod is 3

[0053]

[0054] Table 3 Ventilation rate values when the number of holes on the side of the rod is 6

[0055]

[0056] When the closing suction resistance is 0.6-0.8 kPa, the capillary hole diameter is 0.65-0.70 mm, at which time the ventilation rate of opening a single hole is about 15%-20%. The ventilation rate of opening three holes is about 40%-50%, and the ventilation rate of opening 5-6 holes is about 70%.

[0057] When the closing suction resistance is about 1.0 kPa, the hole diameter is 0.60-0.61 mm, at which time the ventilation rate of opening a single hole is about 20%-25%. The ventilation rate of opening three holes is about 45%-50%, and the ventilation rate of opening 5-6 holes is about 75%-80%.

[0058] When the closing suction resistance is about 2.0 kPa, the hole diameter is 0.49-0.50 mm, at which time the ventilation rate of opening a single hole is about 28%-32%. The ventilation rate of opening three holes is about 60-62%, and the ventilation rate of opening 5-6 holes is about 80%-85%.

[0059] The ventilation rate value and the closing suction resistance value of the rod show a positive correlation, and the ventilation rate value and the capillary hole diameter show an inverse correlation.

[0060] According to the values measured in Tables 1-3, the measured values and the hole diameter changes of the produced ventilation rate standard rod meet the requirements, indicating that the accuracy and stability of the standard rod produced by the method are high.

[0061] Finally, it should be noted that: the above examples are only used to illustrate the technical solutions of the present application and not to limit them; although the present application has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the specific embodiments of the present application can be modified or some technical features can be replaced by equivalent ones; without departing from the spirit of the technical solutions of the present application, they should be covered in the technical solution range of the present application.

Claims

1. A method for producing high-precision multi-channel large-bore glass capillary, characterized in that: The following parts are included: First part: manufacturing composite capillary: Manufacture capillary glass sleeve embryo, the inner diameter of which is ≥1.2 mm, the outer diameter is ≥3 mm, and the length is ≥300 mm. One end of the capillary glass sleeve embryo is closed. A copper column with a higher shape size accuracy than the required accuracy of the inner diameter of the capillary is filled in the inner hole of the capillary glass sleeve embryo. The diameter of the copper column is smaller than the inner diameter of the capillary glass sleeve embryo. The other end of the capillary glass sleeve embryo is connected to a venting device through a pipeline, and then sent to a heating furnace. The capillary glass sleeve embryo filled with the copper column is heated at a high temperature of 850°C-1200°C. On the one hand, the wedge-shaped mold is used to shape the outer contour of the capillary glass sleeve embryo, so that the cross section of the outer contour is wedge-shaped. On the other hand, the venting device is used to inject inert gas into the gap between the copper column and the capillary glass sleeve embryo to maintain or expand the inner diameter to a set size, forming a composite capillary. Second part: multi-hole capillary assembly: The manufactured composite capillary is arranged in a ring shape with wedge-shaped sides, and is arranged in a glass outer sleeve with an outer diameter of ≥9 mm, a wall thickness of ≥3.7 mm, and a length of ≥300 mm. One end of the glass outer sleeve is sealed. One end of the composite capillary connected to the pipeline is exposed outside the glass outer sleeve. A corresponding solid glass core rod is filled between the ring-shaped arranged composite capillaries to assemble a multi-hole capillary assembly. Third part: high temperature stretching: The multi-hole capillary assembly is suspended and sent to a wire drawing heating furnace. After being heated to 1000°C-1200°C, the two ends of the glass outer sleeve are fixed for drawing. In the first time period of starting drawing, the venting device injects inert gas into each composite capillary. The inert gas is used to support and deform the composite capillary under positive pressure to eliminate the gap between the composite capillary, the glass outer sleeve, and the solid glass core rod. In the second time period of starting drawing, the venting device forms negative pressure by external air extraction. The inner diameter of the composite capillary is contracted and tightly attached to the surface of the copper column. Finally, the composite multi-hole capillary rod body with a length of ≥350 mm and an outer diameter of 8-9 mm is stretched in the glass outer sleeve part. Fourth part: annealing, hole forming, and finishing: After being placed in an annealing box for annealing, the temperature is lowered to room temperature. Because the thermal expansion coefficient of the copper column is greater than that of the glass, the contraction amplitude of the copper column in the composite capillary is greater than that of the glass. The gap appears again. At the same time, the appearance is checked to determine whether it is fully fused. Then, the unqualified areas at both ends are cut off. The qualified middle part is taken to a set length, placed in an acidic corrosion solution, and the copper column in the capillary hole is corroded away. After cleaning, the finished product is obtained.

2. The method for producing a high-precision multi-channel large-bore glass capillary according to claim 1, characterized by: After the multi-hole capillary assembly is completed, the other end of the glass outer sleeve is vacuumed and then sealed by fusion to fuse the capillary glass sleeve, the composite capillary, and the solid glass core rod together.

3. The method for producing a high-precision multi-channel large-bore glass capillary according to claim 1 or 2, characterized by: During the multi-hole capillary assembly process, the space formed in the middle region of the composite capillary arranged in a ring shape with wedge-shaped sides has a polygonal or circular cross section. The cross section of the solid glass core rod is polygonal or circular.

4. The method for producing a high-precision multi-channel large-bore glass capillary according to claim 3, characterized by: The acidic corrosion solution includes nitric acid or hydrochloric acid.

5. The method for producing a high-precision multi-channel large-bore glass capillary according to claim 4, characterized by: After the copper column is corroded away and cleaning is finished, the capillary holes are continuously flushed using a cleaning solution containing hard micro-powder, micro-shaping is performed, and glass burrs and micro-particles in the capillary holes are removed.

6. The method of production of high precision multi-channel large-bore glass capillary according to claim 5, characterized in that: The number of the composite capillary tubes is 8-12.

7. The method for producing high-precision multi-channel large-bore glass capillary according to any one of claims 4 to 6, characterized in that: The copper column is a copper alloy or pure copper.

8. The method of producing high precision multi-channel large bore glass capillary according to claim 1, characterized in that: The glass is low-expansion hard glass.

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