JP2758974B2 - Furnace for heating and vacuum forming bottomed tubes - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a structure of a furnace capable of heating and vacuum forming a bottomed tube in a short time.

[Related Art] In an automatic chemical analyzer or the like, a test sample is accommodated in a transparent reaction cell and irradiated with light for analysis and measurement. As the reaction cell, a square tube with a bottom is usually used. For example, the reaction cell is formed by heating and vacuum forming a cylindrical tube with a bottom made of glass or quartz. One of the producing methods used at that time is described in, for example, Japanese Patent Publication No. 1-38055.

FIG. 3 is a diagram for explaining the creation method described in the above publication. In FIG. 3, 1 is an electric furnace,
The heater 2 is installed at the inner bottom. In this electric furnace, a bottomed cylindrical tube 4 made of glass or quartz into which a metal core 3 precisely processed into a desired shape is inserted is slowly and gradually inserted from above. The open end of the bottomed cylindrical tube 4 that is exposed outside the furnace is connected to a vacuum pump (not shown) via a connection tube 5, and the inside thereof is constantly maintained in a vacuum state.

Then, the bottomed cylindrical tube 4 is gradually heated from the bottom portion by the heater 2 disposed at the inner bottom portion of the electric furnace, and the softened glass or quartz is applied to the inner core metal by a pressure difference between the inside and the outside of the tube 4. Since it is pressed, it is molded according to the outer shape of the cored bar 2.

[Problems to be Solved by the Invention] By the way, in the heating vacuum molding, if gas remains between the cored bar and the tube, bubbles are generated in the portion and the molding accuracy is reduced. It is necessary to gradually perform molding from the end portion and gradually extract gas from that side to prevent bubbles from being generated.

Therefore, in the above-described conventional heating vacuum forming method, the bottomed tube 4 is gradually and gradually lowered into a heating furnace having a heater disposed on the inner bottom, and the heating vacuum forming is gradually performed from the bottom.

However, if the bottomed tube is gradually lowered slowly in this way, it is inevitable that the time required for one molding becomes long, and a mechanism for slowly lowering the bottomed tube at a constant speed is required. And complicated speed control is also required.

In addition, there is also a problem that the generation of bubbles described above is not necessarily eliminated. This is because even if it is lowered gradually, the heat of the core metal does not enter into the electric furnace, and the heat from the part that does not enter the furnace is dissipated to the outside. It seems that the temperature does not rise to the temperature required for molding, the temperature of the core rises as soon as the entire core enters the electric furnace, and heating vacuum molding starts with the entire bottomed tube . This means that in an electric furnace as shown in Fig. 3, the bottom part close to the heater and the upper part where the hot air rises and stagnates are hotter than the other parts. Also seems to be a factor.

If such bubbles are formed, it is necessary to cool them once to form a gap between the cored bar and the bottomed tube, and then perform heating and vacuum molding again. If bubbles cannot be removed, the process must be repeated. Conventionally, molding has been repeated about four times on average, so if the time required for cooling is added, the overall molding time becomes extremely long.

Then, the present inventors set the quartz tube 6 upright on the heater 2 arranged at the bottom of the furnace 1 as shown in FIG. 4, and inserted the cored bar 3 into the quartz tube 6. 4 was tried at once. In this way, the bottomed tube 4 inserted at a stretch is heated by the high-temperature air that is heated and raised by the heater 2 disposed at the bottom, and the bottom of the bottomed tube 4 is radiated by the heat radiation from the heater 2. Therefore, it is considered that the temperature of the bottomed tube 4 becomes higher toward the bottom, and the bottomed tube 4 is gradually molded from the bottom to reduce the generation of bubbles. In addition, even if the temperature inside the quartz tube drops once by inserting the bottomed tube at a stretch, the temperature is quickly recovered because it is heated by the rising air and surrounded by a quartz tube with a considerable heat capacity. However, it was thought that even if it was inserted all at once, there was no adverse effect on the molding.

However, even in this method, the number of air bubbles does not necessarily decrease, so that the state in which the molding must be repeated about four times was not much different from the conventional example shown in FIG.

This is because the heater, which is the heat source, exists only at the bottom of the furnace, so the bottom near the heater and the high-temperature air rise in the quartz tube and the stagnated top becomes hotter than the other parts. Therefore, it is presumed that the molding of the bottomed tube started from the bottom and the top, and that the ideal molding gradually from the bottom was not performed, and bubbles were generated.

The present invention has been made in view of the above-described points, and has as its object to provide a furnace capable of heating and vacuum forming a bottomed tube in a short time.

Means for Solving the Problems In order to achieve this object, a furnace according to the present invention comprises a tubular radiator arranged such that one end thereof communicates with the outside in the furnace, and a tubular radiator disposed around the tubular radiator. And a heating element
The present invention is characterized in that the tubular radiator is heated by heat radiation from the heating element, and an object to be heated is inserted into the tubular radiator from the outside through a communication port to heat the tubular radiator.

[Operation] In the present invention, a tubular heat radiator is arranged in a heating furnace, and the tubular heat radiator is uniformly heated by heat radiation from a heater arranged around the heat radiator. Is inserted to heat and vacuum form the bottomed tube.

Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a sectional view showing the structure of one embodiment of the present invention, and FIG.
The figure is a sectional view taken along the line AA in FIG. 1 and 2, the inner surface of the heating furnace main body 11 is surrounded by a heat insulating wall 12 made of glass wool or the like, and the upper part thereof is covered by a double heat insulating lid 13, 14. Numeral 15 is a quartz tube which is arranged upright in the heating furnace, and four tubes are arranged in a row at substantially equal intervals, and three rows are provided at appropriate intervals. The upper end of each quartz tube is inserted into and fixed to a hole 16 formed in the heat-insulating lid 13 according to the position and outer diameter of the quartz tube, and the lower end thereof is a spacer 17 made of a heat insulating material.
Are positioned so as not to shift in the lateral direction.

On the spacer 17, four rod-shaped heaters 20 each containing a heating element 19 in a quartz tube 18 are arranged so as to sandwich three rows of the quartz tubes 15 therebetween. Further, the heat-insulating lid 14 has an insertion opening for inserting a bottomed tube 23 as a molded object into the quartz tube 15.
21 is opened in accordance with the position of the quartz tube 15. 22 is
This is a connection pipe for connecting the bottomed pipe 23 to a vacuum pump (not shown). All the bottomed tubes 23 are integrally inserted into and removed from the quartz tube 15 through the insertion port 21 by a holding and vertical movement mechanism (not shown).

In the above configuration, the surfaces of the quartz tubes 15 and 18 are frosted glass surfaces by performing processing such as grinding stone processing,
It is in an opaque state. Therefore, when the heating element 19 is energized to generate heat and heat the quartz tube 18 to a uniform high temperature over the entire length, infrared rays are emitted from the surface of the quartz tube 18 in all directions. Then, the quartz tube 15 which has received the infrared rays radiated from the quartz tube 18 also effectively absorbs the infrared rays due to the unevenness of the surface thereof, and has a high temperature over the entire length. Of course, the air in contact with the heater is also heated by the heater, and the convection of the heated air also heats the quartz tube 15.

The inside of the quartz tube 15 heated to a high temperature over the entire length in this manner is set at substantially the same temperature at the bottom, the top, and the middle. In this way, the bottomed tube 23 containing the cored bar is inserted at once through the insertion port 21 into the quartz tube 15 which is substantially at the same temperature, and the position shown in FIG. The bottom portion of the bottom tube is disposed at a position where it is sandwiched by the heater 20. The inserted bottomed tube 23 is uniformly heated as a whole by heat transfer from the air heated to a high temperature in the quartz tube 15 and heat radiation from the quartz tube 15, and the temperature rises rapidly. At that time, heating is performed uniformly throughout, but the end of the bottomed tube is exposed outside the furnace near normal temperature, and heat is dissipated toward that end, so the bottomed tube as a whole has a bottom The temperature is highest, and a relatively gradual temperature gradient occurs in which the temperature gradually decreases toward the top. For this reason, the bottomed tube is gradually heated and vacuum-molded from the bottom, and it is possible to perform nearly ideal heating-vacuum molding.

As a result of implementing the present invention, the generation of bubbles is significantly reduced,
With at most two vacuum heating moldings, it was possible to produce a product equivalent to that produced by four moldings so far. As a result, the overall molding time was significantly reduced, and the productivity was significantly improved.

Immediately after the bottomed tube 23 is inserted, the temperature inside the quartz tube 15 temporarily drops, but the inserted bottomed tube 23 is surrounded by the quartz tube 15 having a large heat capacity arranged near the bottomed tube. Because of being enclosed, the internal temperature of the tube is rapidly restored by receiving heat radiation from the quartz tube 15. Therefore, the temperature of the bottomed tube 23 also rises rapidly, and one heating vacuum forming is completed in a short time.

In the above-described embodiment, the frosted glass surface-treated quartz tube 15 was used as the tubular heat radiator for heating the bottomed tube, but the heat radiation from the heater arranged around the tube was uniformly absorbed. Other materials may be used as long as they are efficiently heated, withstand high temperatures, and efficiently radiate heat toward the bottomed tube inside.

Further, in the above-described embodiment, the heater 20 having the heating element 19 passed through the quartz tube 18 is used. However, the heater 20 is not limited to this, and an appropriate heating element may be used as long as it radiates infrared rays uniformly. It is possible. The shape and position of the heater are not limited to those in the above-described embodiment. For example, a long plate-shaped heater may be arranged as shown by a broken line in FIG.

[Effects of the Invention] As described above in detail, according to the present invention, a tubular heat radiator is disposed in a heating furnace, and the heat radiator is uniformly heated by heat radiation from a heater disposed around the heat radiator, and is internally heated. Since the bottomed tube into which the cored bar is inserted is inserted into the heat radiator to perform the heating vacuum molding, the bottomed tube can be molded in a short time.

[Brief description of the drawings]

FIG. 1 is a sectional view showing the structure of an embodiment of the present invention, FIG. 2 is a sectional view taken along line AA in FIG. 1, FIG. 3 is a view for explaining a conventional method, and FIG. FIG. 6 is a diagram for explaining a method tried by a user. 11: Heating furnace body, 12: Insulated wall 13, 14: Insulated lid, 15, 18: Quartz tube 16: Hole, 17: Spacer 20: Heater, 21: Insertion port 22: Connection tube, 23: Bottomed tube

Claims (1)

(57) [Claims] 1. A tubular heat radiator arranged so that one end thereof communicates with the outside in a furnace, and a heat generator disposed around the tubular heat radiator, and the tubular heat radiator is radiated by heat radiation from the heat generator. A furnace for heating and vacuum forming a tube with a bottom, wherein the body is heated and an object to be heated is inserted into the inside of the tubular heat radiator from the outside through a communication port and heated.