JPS61136931A - Manufacture of glass capillary tube - Google Patents

Abstract

PURPOSE:To obtain the titled glass capillary tube provided with excellent dimensional accuracy and a homogeneous protective coat and used for gas chromatograph by regulating the deviation value between the measured outer diameter of a wiredrawn glass capillary tube and a set value and the internal pressure of the glass base material. CONSTITUTION:A compressed gas is supplied from an opening at one end of a glass tube. The other end part of the glass tube is heated and melted by a wiredrawing furnace 5, and the glass is wiredrawn by the following method to manufacture a desired glass capillary tube. The outer diameter of the wiredrawn glass capillary tube 8 is measured, and the deviation value between the measured value and a specified set value of the outer diameter is obtained. The deviation value is fed back to the wiredrawing velocity of the capillary tube, and the wiredrawing velocity is controlled so that the outer diameter of the capillary tube may be kept constant. Besides, the deviation value between the wiredrawing velocity resulting from the control of the outer diameter and a specified set value of the wiredrawing velocity is fed back to a pressure controller 13 for supplying compressed gas through a PID control amplifier 10 to control the internal pressure so that the set value of the wiredrawing velocity may be obtained.

Description

[Detailed description of the invention] <Industrial application field> The present invention relates to a method for manufacturing glass capillaries.

<Prior Art> In recent years, a large amount of quartz capillary tubes used in capillary columns for gas chromatography have been back-channeled by applying the drawing technology of quartz-based original fibers. As a manufacturing method of such a glass capillary tube, conventionally, for example, Patent Publication No. 5
The one shown in No. 7-3726 is known.

As shown in FIG. 2, in this conventional technique, a quartz tube 1 is attached to a glass tube feeding device 2, the lower end of the quartz tube 1 is fed into a high temperature wire drawing furnace 5, and the lower end of the quartz tube is melted and wire drawn. death,
After applying the resin to a desired thickness through the coating dye 4 storing the heat-resistant resin solution 3, the resin is baked and hardened in the baking furnace 11, and the resin-coated glass capillary tube 8 is driven by the winding device 6. Wind it up on the winding citram 7. At this time, a pressurized gas such as nitrogen gas is supplied into the quartz tube 1 by a pressure regulator 12 connected to the upper end of the quartz tube 1 by a gas supply pipe to apply internal pressure, and the quartz tube 1 is melted in the drawing furnace 5. Due to the influence of surface tension in the molten part, the drawn capillary tube
While preventing the wall thickness from becoming relative KM, the outer diameter measuring device 9
The outer diameter of the capillary is measured by the method, and the winding speed of the drum winding device 6 is increased to prevent the outer diameter from being expanded by the pressurized gas, thereby obtaining a silica-based glass capillary having a predetermined inner diameter and outer diameter. Items 1-10 are amplifiers.

<Problems to be Solved by the Invention> Incidentally, the characteristics of the glass capillary tube of the capillary column require dimensional accuracy of the inner diameter rather than the outer diameter and high mechanical strength. Regarding mechanical properties, the homogeneity of the heat-resistant resin coating is extremely important. However, in the prior art shown in FIG. 2, the accuracy of the inner diameter of the glass capillary
There was also a problem with the longitudinal homogeneity of the heat-resistant resin coating due to variations in drawing speed. Even if the dimensions of the starting base material glass tube are uniform in the longitudinal direction, the inner and outer diameters of the glass capillary obtained by drawing the glass tube are affected by temperature fluctuations in the drawing furnace, internal pressure fluctuations in the glass tube, etc. fluctuates due to external disturbances.

The outer diameter of a drawn glass capillary can be highly accurate by controlling the drawing speed, but the inner diameter cannot be directly controlled because there is no way to monitor it with high precision during drawing, and in addition to the above disturbances. However, there is the problem that further fluctuations occur due to fluctuations in drawing speed due to outside diameter control. Variations in the drawing speed due to control of the outer diameter of the glass capillary tube have the problem of varying the degree of hardening of the heat-resistant resin coating and reducing the homogeneity of the coating.

The present invention has been made in view of the problems of the prior art, and aims to provide a method for manufacturing a glass capillary tube that improves the accuracy of the inner diameter dimension and has a heat-resistant resin coating that is homogeneous in the longitudinal direction. be.

Means for Solving the Problems〉 The structure of the method for manufacturing a glass capillary tube according to the present invention that achieves the above object is to supply pressurized gas from one end of the glass tube that is supplied to the drawing furnace, and to In a method of manufacturing a glass capillary by heating and melting the other end in a drawing furnace and drawing the wire, the outer diameter of the drawn glass capillary is measured, and the measured value and the set value of the outer diameter of the glass capillary are combined. The deviation value is calculated, the deviation value is fed back to the drawing speed of the capillary tube, the drawing speed is controlled to keep the outer diameter of the capillary constant, and the drawing speed is identified as the drawing speed caused by the outer diameter control. The deviation value from the set drawing speed is fed back to the pressure control device that supplies the pressurized gas via the PID control system amplifier, so that the drawing speed becomes the set drawing speed. The invention is characterized in that the internal pressure is controlled by the pressurized gas.

Function> In the method for manufacturing a glass capillary according to the present invention, for example, the inner diameter Di is constant and the outer diameter is constant. Apply internal pressure to a hollow glass tube with a constant feed rate V.

are supplied to the drawing furnace as predetermined values, and the desired inner diameter di and outer diameter d are supplied from the drawing furnace. It is drawn in a stable state as a glass capillary with Therefore, the following equation holds.

VO8□ = v 6 s smile S. is the cross-sectional area of the glass tube, 5o=(Do Di) So is the cross-sectional view of the glass capillary, So = '-(d g d12), so V. so
If is constant, vot-S if specified. is also specified.

The outer diameter of 98° is d. If it is specified, the inner diameter di is specified. In addition, if the cross section 8t of the glass tube changes in the longitudinal direction, the supply speed of the glass tube is changed according to the change, and the supply speed is adjusted to a predetermined value so that the product of the cross sectional area and the supply speed is constant. Sometimes I follow the changes. Therefore, in the present invention, the cross-sectional area S. A glass tube of is supplied to a drawing furnace at a predetermined speed v0, the outer diameter of the capillary tube drawn from the drawing furnace is do, and the drawing speed is V. By controlling the drawing speed and the internal pressure of the glass capillary, a glass capillary having a desired outer diameter do and a desired inner diameter di can be obtained.

<Example> A method for manufacturing a glass capillary according to the present invention will be described with reference to the drawings using an example of a glass capillary manufacturing apparatus shown in FIG.

In the configuration diagram of an apparatus for explaining one embodiment of the present invention shown in FIG. 1, the base material of the glass capillary is, for example,
A quartz tube 1 with a wall thickness of 5 ml is attached to a glass tube feeder &2, and a gas supply tube 14 is connected to the upper end of the quartz tube 1, and a pressure controller 13 controls the supply of nitrogen, etc. Pressure gas is supplied. Further, the lower end of the quartz tube l is placed at an optimal position in the drawing furnace 5 at a constant speed (2) by the glass tube feeding device 2. It is sent in. The lower end of the quartz tube l is heated to about 2000° C. in a drawing furnace 5 to a molten state, and is drawn at a specific drawing speed V while maintaining a tubular shape with a desired outer diameter d0 and inner diameter di. The heat-resistant resin solution 3
After being applied through coating die 4,
It is baked and hardened in a baking furnace 11 and wound onto a winding drum 7. In the device shown in FIG. 1, the quartz tube 1 is fed at a constant feed rate, for example V. = 1, 25 ml min is supplied, and the glass capillary is drawn at a speed v□ = 10 m/
! The speed is controlled by n1n, and the outer diameter of the glass capillary is d. ;
When the outer diameter is controlled to the set value of 300 μm, the inner diameter di becomes 2
00 μm glass capillary tubes are obtained. That is, the outer diameter d of the drawn glass capillary tube 8 is measured by the outer diameter measuring device 9, and the measured value d is the outer diameter setting value d of the glass capillary tube. 1,300 thousand
μm is compared in the input amplifier 10, and the deviation value is fed back to the drawing speed command signal of the motor of the drum winding device 6, and the drawing speed of the glass capillary tube is changed, and the outer diameter of the glass capillary tube is set to the set value. control so that it becomes do.

Further, the wire drawing speed set value v0 is input to the amplifier 10, and the speed command signal of the motor of the drum winding device 6 is proportional to the wire drawing speed vK. .

and the drawing speed V, and calculate the deviation value between
Output to 0'. The output of the amplifier 10' is connected to the pressure control device 1.
3, and the drawing speed is controlled so as to approach do. Accordingly, the drawing speed is controlled so as to approach the set value v0. As a result, the outer diameter is d. 2300μm.

The drawing speed was controlled at 76 = 10 mlmin, and the inner diameter di = 200. Cua glass capillary tubes will be stably supplied. The above-mentioned internal pressure control is such that in order to keep the outer diameter of the glass capillary tube 8 constant, the internal pressure is lowered when the drawing speed increases, and conversely, the internal pressure is increased when the drawing speed decreases.

Measurement of inner and outer diameters and drawing speed fluctuations of glass capillary tubes drawn using the method of the present invention at a drawing speed of 15 ml min and glass capillary tubes obtained by the conventional method shown in Factor 2 Examples of the results are shown in Table 1.

Table 1 As is clear from Table 1, according to the method for manufacturing a glass capillary according to the present invention, fluctuations in the inner diameter of the glass capillary can be suppressed to the same level as in the conventional case, and fluctuations in drawing speed can also be significantly reduced. Also, when applying and baking a polyimide resin as a heat-resistant resin, unevenness was observed in the longitudinal direction in the conventional method, but with the method according to the present invention, an extremely homogeneous coating can be stably produced.

In the above embodiments, quartz glass was used as the glass base material, but the present invention is not limited to quartz glass, and any glass that can be drawn can be used.

<Effects of the Invention> According to the method for manufacturing a glass capillary according to the present invention, the outer diameter of the glass capillary drawn into the glass capillary is measured, compared with the outer diameter setting value, and the deviation value is determined. Feedback is provided to the motor speed of the winding device, and
The drawing speed controlled by the outer diameter deviation value is compared with the set value, and the deviation value is input to the pressure control device that adjusts the internal pressure of the glass base material of the glass capillary through the amplifier of the PID control system. By drawing the wire based on the internal pressure of the glass base material, the inner and outer diameters of the glass capillary can be precisely specified, and fluctuations in the drawing speed are also reduced, resulting in excellent dimensional accuracy and a homogeneous protective coating. Glass capillary tubes for gas chromatography can now be obtained.

[Brief explanation of drawings]

FIG. 1 is a block diagram of an apparatus for explaining an embodiment of the glass capillary manufacturing method according to the present invention, and FIG. 2 is a block diagram of an apparatus for explaining a conventional method. In the drawings, 1 is a quartz tube, 2 is a glass tube feeding device, 3 is a heat-resistant resin solution, 4 is a coating die, 5 is a wire drawing furnace, 6 is a drum winding device, 7 is a winding drum, 8 is a glass capillary tube, 9 is an outer diameter measuring device, 10 is an amplifier, 10' is a PID amplifier, 11 is a resin baking furnace, and 13 is a pressure control device.

Claims (1)

[Claims] A method of manufacturing a glass capillary by supplying pressurized gas from an opening at one end of a glass tube, heating and melting the other end of the glass tube in a drawing furnace, and drawing the drawn glass. The outer diameter of the capillary is measured, the deviation value between the measured value and the set value of the outer diameter of the glass capillary is determined, and the deviation value is fed back to the drawing speed of the capillary to keep the outer diameter of the capillary constant. At the same time as controlling the drawing speed, the deviation value between the drawing speed generated by the outer diameter control and the specified drawing speed setting value is determined by the pressure for feeding the pressurized gas through the PID control system amplifier. A method for manufacturing a glass capillary tube, characterized in that the internal pressure by the pressurized gas is controlled so that the wire drawing speed becomes the wire drawing speed setting value by returning to a control device.