JPS5940770B2 - Continuous forming equipment for glass tubes or rods - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a continuous forming apparatus for glass tubes or rods having precisely controlled dimensions, particularly outer diameters.

Conventionally, when a material such as glass, whose mechanical properties change continuously from a viscous body to a solid as the temperature decreases, is continuously formed into a tube or rod, the molten glass is formed through an outlet with an appropriate shape. The molded product is pulled out further and the temperature is continuously lowered to obtain a molded product of the required size.

In general, when forming a bar, the outer diameter is determined by the tensile speed of the compact, the temperature distribution of the compact in the drawing direction, and when forming a tube, the pressure of the gas fed into the pipe is determined by the above factors. adjusted.

Conventionally, in order to obtain a molded body with constant dimensions, it has been done to keep the above-mentioned and other factors that affect the molding state as constant as possible, and for this purpose, the tensile speed or the pressure of the injected gas has been changed. is maintained constant using feedback control technology.

In addition to the above-mentioned controllable factors, the dimensions of the compact are continuously adjusted to eliminate the influence of factors that vary irregularly and are difficult to control, such as thermal convection of air flowing into the forming section. A method has been proposed in which a molded article having a desired size is obtained by measuring the size of the molded article and adjusting controllable factors such as the above-mentioned pulling speed or gas pressure.

(For example, see Japanese Patent Publication No. 45-14917.) However, in the method described above, there is a considerable amount of time between the time when the molded body is molded and the time when the dimensional measurement results are obtained, so the above-mentioned adjustment operation cannot be performed automatically. However, if the dimensions of the molded body fluctuate in a shorter time than the required measurement time due to some factor fluctuation, the fluctuation cannot be removed.

In general, a non-contact forming method for glass, that is, a method for forming glass tubes or rods in which the surface of the formed object is not supported by other solid walls during the process in which the formed object transitions from an amorphous shape to a regular shape, that is, in the process of being given a shape; Specifically, the Dunchy method, the Bellow method,
In forming methods such as the up-draw method in which glass is drawn into tubes or rods from molten glass, the force that determines the shape of the formed object is generated by thermal, fluid, and mechanical equilibrium between the formed object and the space surrounding it. The controllability is poorer than that of contact molding methods such as press molding and extrusion molding.

Therefore, even if the factors that influence molding are kept as constant as possible, dimensional variations in the molded product still remain.

The object of the present invention is to eliminate the fluctuations in dimensions, that is, the outer diameter, inner diameter, or wall thickness that occur during the forming process of glass tubes or rods, by controlling the main body of the continuous molding apparatus as in the prior art, but by is corrected by a dimension correction device provided close to the molding device, thereby obtaining a product having highly accurate dimensions.

Accordingly, the object of the present invention is to provide a continuous forming apparatus for glass tubes or rods, in which a tube or rod-shaped glass is continuously drawn out from molten glass, cooled, and formed into a predetermined size.
A dimension measuring device for measuring the dimensions of a molded glass tube or rod and a dimension correction device for the glass tube or rod are provided in close proximity to the continuous molding device main body, and dimension side fixing and dimension setting values obtained from the dimension measuring device are provided. This is achieved by detecting the deviation between the two and operating a size correction device to correct the size of the glass tube or rod so as to reduce said deviation.

In a more preferred embodiment of the present invention, a second dimension measuring device is provided close to the dimension correcting device on the glass traveling direction side, and measures again the dimensions of the glass tube or rod that have been corrected by the dimension correcting device, Based on this measurement, the operation of the dimension correction device is adjusted.

The attached drawings, FIGS. 1 and 2, provide a detailed explanation of the present invention. In the figures, 1 indicates the main body of a continuous glass tube forming apparatus using a set of dunners, and the glass tube 2 formed by this apparatus is rolled by rolls 3. The tag is transported forward and cut into predetermined lengths by the tag cutting device 4 to produce products.

Immediately after molding, the glass tube 2 is continuously measured by a dimension measuring device 5, for example, its outer diameter dimension, and a signal indicating the measured value is transmitted to the control device 8, which then calculates the difference between the dimension and the set value. When a deviation is detected, a correction operation command signal based on this deviation is transmitted to a dimension correction device 6 disposed in succession to the dimension measuring device 5, and the dimension is corrected.

The dimensional correction device is required to have a dimensional correction capability equal to or greater than that during the maximum dimensional change of the glass tube generated from the main body of the continuous molding apparatus, and to be able to respond temporally to the speed or period of dimensional change.

As shown in FIG. 1, it is preferable to provide a second dimension measuring device 7 close to the modification device 6 on the glass traveling direction side, which measures the dimensions of the glass tube that has undergone the modification process again and controls the results. This information is transmitted to the device 8, which determines whether or not the correction operation amount is appropriate for the deviation, and if it is inappropriate, adjusts the correction command.

Correction operations can be performed for both positive and negative deviations from the set value, but in order to simplify the mechanism of the correction device, correction operations are performed for deviations that are either positive or negative. It is preferable to control the molding conditions of the molding apparatus main body so as not to exceed the upper or lower limit of the range of variation.

The foregoing with respect to FIG. 2 will now be further explained.

FIG. 2a shows a graph in which the results of measuring glass tubes formed by a continuous molding device using a dimension measuring device are plotted against time, and the dotted lines indicate the upper and lower limits of the range of variation, that is, the maximum and minimum of the variation.

Figures 2 and 2C show the dimensions of the glass tube that underwent the modification process.

FIG. 2 shows a case in which settings are made to perform a correction operation so that the lower limit of the variation width is met, and FIG.

The arrowed part in FIG. 2 shows the case where the corrective operation amount is excessive with respect to the deviation amount.

In such a case, the correction operation amount command is adjusted.

The dimension measuring device is a non-contact optical measuring device that optically sweeps and irradiates the glass tube or rod with a laser beam, so that the measurement can be carried out at a high temperature such that the glass tube can be evenly deformed.
A type of tube is used in which the shadow pattern of the resulting image is detected by a light receiving device such as a phototube, and the outer diameter, inner diameter, or wall thickness of the tube is measured.

As the dimension correction device, a heating element provided surrounding the advancing glass tube can be used, which heats the glass to reduce its viscosity and reduce the traction force (tension) transmitted by the tension device.
elongate the glass tube and reduce its outer diameter, inner diameter, or wall thickness.

As the heating element, a group of ring burners, an electric heating coil, an induction heating element, etc. are preferably used.

In order to make a correction to increase the outer diameter of a glass tube, the glass tube is fed into a pressure reducing device near its softening point, and the pressure difference between the inside of the tube, which is maintained at almost atmospheric pressure, causes the glass tube to increase. can be made to expand.

A detailed description of the invention will be provided with reference to FIG.

Reference numeral 11 indicates a main body of a glass tube forming apparatus with a complete dunner, and the glass tube 12 immediately after forming enters a dimension measuring apparatus 13.

This device is an optical non-contact pipe diameter measuring device using laser light, and includes a light projecting system 14, a light receiving system 15, and a signal processing circuit 16.
It consists of

17 indicates a dimension correction device consisting of a group of ring burners;
The group of burners includes a combustion gas source 18 and an oxygen or air source 19.
The combustion gas mixture is then supplied via the mixer 22 by means of a remotely and automatically adjustable control valve 20.21.

The opening degrees of the control valves 22 and 23 are controlled by instructions from a computer, for example, the process computer 15.

A second dimension measuring device 24 is disposed on the side of the dimension correcting device in the direction in which the glass travels, and transfers the measured value of the tube diameter after the correcting operation to the computer 23 .

The calculator 23 is further equipped with a dimension target setter 25.

The computer 23 performs the calculations listed below in real time, and controls the opening degrees of the control valves 20 and 21.

■) Collection of dimension measurement values from the dimension measuring machine 13 2) Calculation of deviation between set value and measured value 3) Calculation of correction operation amount 4) Calculation of correction operation delay time 5) Command of correction operation 6) Collection of dimension measurements from the second dimension measurement device 24 7) Calculation of the deviation between the set value 6) and the measured value 8) Calculation of the correction coefficient 9) Modification of the correction coefficient In the case of the example explained above, Since tension is acting on the glass tube, the temperature of the glass tube increases due to the heating operation by a group of ring burners, and the tube diameter decreases.

Therefore, since the deviation correction operation is performed only on the negative side, it is necessary to operate the dimensions of the glass tube obtained from the continuous forming apparatus main body so that the lower limit of the variation does not become less than the target dimension.

As is clear from the above description, the device configuration of the present invention is different from the conventional fixed value control of molding conditions or feedback control using target dimensions, and can be said to be
This method can be said to be based on the concept of "feed forward" control, and there is no limit to controllability due to measurement delays as in the former, and it is possible to eliminate rapid dimensional fluctuations and continuously obtain high-precision molded objects. shall be.

Although the present invention has been described above with respect to a glass tube or rod forming apparatus using the Danchy method, it can also be applied to other methods such as the bellows method and the up-draw method.

[Brief explanation of drawings]

FIG. 1 is a block diagram explaining the present invention in detail, FIG. 2 is a graph showing temporal variations in the dimensions of a glass tube explaining the present invention in detail, and FIG. 3 is a block diagram showing a specific example of the present invention. shows. 1.11...Dunner set glass tube continuous forming device main body, 2,12...Glass tube, 5,13...
... Dimension measuring device, 6, 17... Dimension correction device, 7, 24... Second dimension measuring device.

Claims (1)

[Scope of Claims] 1. In a continuous forming device for glass tubes or rods, which continuously draws out a tube or glass rod from molten glass, advances it, cools it, and forms it into a predetermined size, A dimension measuring device for measuring the dimensions of the glass tube or rod and a correction device for modifying the dimensions of the glass tube or rod are sequentially provided in the direction of the execution force of the glass tube or rod, and the dimensions obtained by the dimension measuring device are Detecting the deviation between the measured value and the dimension setting value, and correcting the dimension of the glass tube or rod by operating a dimension correction device provided in the forward force of the dimension measuring device to reduce the deviation. A continuous forming device for glass tubes or rods. 2. The device according to claim 1, wherein the dimension correction device is a heating element that surrounds the advancing glass tube or rod and heats it from the outer surface. 3. The apparatus of claim 2, wherein the heating element is a group of ring burners. 4. In a continuous glass tube or rod forming device that continuously draws out a tube or glass rod from molten glass while advancing it, cooling it and forming it into a predetermined size, 1st to measure the dimensions
A dimension measuring device, a device for correcting the dimensions of the glass tube or rod, and a second dimension measuring device are sequentially provided in the direction of the execution force of the glass tube or rod, and the dimension measurement obtained by the first dimension measuring device is performed. After activating the size correction device to reduce the deviation between the value and the size setting value, measure the corrected glass tube or rod size again by the second size measurement device and based on this measurement. 1. A continuous forming apparatus for glass tubes or rods, characterized in that the operation of the size adjusting device is adjusted by adjusting the size. 5. The device according to claim 4, wherein the dimension correction device is a heating element that surrounds the advancing glass tube or rod and heats it from the outer surface. 6. The apparatus of claim 5, wherein the heating element is a group of ring burners.