JPH10152329A - Glass melting furnace - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a structure capable of eliminating a thermal fluctuation of a discharge pipe due to heat and stably fixing the discharge pipe inside a glass melting furnace or at a nozzle port, with the glass melting furnace having the inner wall of the furnace body and the discharge pipe, directly contacting with the molten glass, made of platinum or platinum alloy, in order to suppress a reaction of molten glass with a material constituting the inner wall of the glass melting furnace. SOLUTION: This glass melting furnace comprises an inner wall and a discharge pipe 2, i.e., directly contacting parts with molten glass, made of platinum or platinum alloy in order to suppress a reaction of the glass with a material constituting the furnace, and is so constituted as to absorb a thermal fluctuation (expansion or contraction) of the discharge pipe 2 due to heat by the aid of the deformation of the inner wall of the furnace consisting of platinum or platinum alloy.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a process for manufacturing glass products such as optical elements, in which glass is melted in a glass melting tank, and the melted glass is caused to flow out of a furnace through an outflow pipe. Glass melting furnace,
The present invention relates to a structure of a glass melting furnace in which an inner wall and an outflow pipe of the glass melting tank are made of platinum or a platinum alloy.

[0002]

2. Description of the Related Art Conventionally, in an optical glass melting furnace, there is little reaction with molten glass in a glass melting tank which is a main body part of a furnace for melting and refining glass and an outflow pipe which is an outflow part for discharging glass. Platinum material is used for the refractory brick or, if necessary, its inner wall,
A heater for heating is installed on the outer peripheral portion of the main body portion of the furnace, so that a temperature necessary for melting the glass can be obtained. Similarly, a heater is installed on the outflow portion. Alternatively, the temperature required for the outflow of the glass can be obtained by directly energizing and heating the platinum member constituting the outflow portion.

[0003]

However, in the conventional glass melting furnace, neither the furnace main body nor the outflow portion is particularly provided with a measure against thermal expansion, and the entire furnace is simply covered with a refractory, and a gantry is provided. , There were the following problems.

[0004] Due to the thermal expansion of the furnace body and the outflow pipe of the glass melting furnace, the nozzle port, which is the outflow tip of the outflow pipe, is displaced from the initial mounting position. With the receiving mold that controls the molding,
The position of the center in the horizontal direction is displaced, and the outflow glass block cannot be accurately supplied to a desired portion of the receiving mold. For this reason, the finished product after molding may protrude from the mold or cause uneven thickness, resulting in deterioration of quality and decrease in yield.

The thermal expansion of the furnace body and the outflow pipe of the glass melting furnace, in particular the latter thermal expansion, between the nozzle opening at the outflow tip of the outflow pipe and the receiving mold receiving the outflow glass;
Since the distance of the glass in the vertical drop direction changes, the outflow amount of the outflow glass fluctuates. For this reason, the weight of the molded product changes, which leads to the deterioration of the quality and the reduction of the yield as described above.

[0006] When the operation of the glass melting furnace is started, or when the temperature of the furnace is changed by changing the melting / outflow conditions, until the deformation due to thermal expansion / contraction caused by the temperature change of the furnace body and the outflow pipe becomes stable. Waiting time is required, and there is a drop in mass productivity due to the occurrence of such invalid time.

During operation of the glass melting furnace, unpredictable permanent deformation may occur due to repeated thermal expansion deformation of the furnace body and the outflow pipe. At the outflow tip (nozzle port) of the outflow pipe leading to the glass outflow tank, in the vicinity of the outflow pipe and the nozzle port, electrode terminals attached to heat them by direct energization, and to energize and hold them The state of the outflow glass changes due to the deformation of the outflow pipe and the nozzle port with repeated thermal expansion deformation between the fixed support portion and the fixed support portion, and as a result, the yield of molded products is reduced. .

The present invention has been made based on the above circumstances, and has as its object to provide an outflow pipe for melting glass in a furnace main body and for discharging the melted glass out of the furnace. In order to suppress the reaction between the molten glass and the furnace material constituting the furnace inner wall, the glass melting furnace in which the inner wall of the furnace body, which is the contact portion with the molten glass, and the outflow pipe are made of platinum or a platinum alloy The object of the present invention is to provide a structure in which heat fluctuation of the outflow pipe, particularly the nozzle port due to heat is eliminated, and the nozzle port from which the glass flows out is stably fixed.

In particular, in this embodiment, the structure of the present invention is designed to prevent the above-mentioned fluctuations in expansion and contraction due to heat from being caused only by the furnace bottom and the vicinity of the outlet pipe mounting part, which forms a part of the furnace body. By focusing on the side wall of the furnace and absorbing it,
The outflow pipe of the glass melting furnace and especially the nozzle port can be stably held.

It is another object of the present invention to further securely fix the nozzle port at the tip of the outflow pipe to a support member which is hardly affected by positional movement due to heat, so that the tip of the outflow pipe at the time of outflow can be obtained. Another object of the present invention is to provide a structure for further stabilizing the positional relationship between the glass and the glass receiving mold.

[0011]

In order to achieve the above object, according to the present invention, glass is melted in a glass melting tank, and the molten glass is caused to flow out of the furnace through a glass outflow pipe. In order to suppress the reaction between the furnace and the furnace materials that make up the furnace, the inner wall and outflow pipe of the furnace, which are in direct contact with the molten glass, flow out in a glass melting furnace made of platinum or a platinum alloy. The method is characterized in that heat fluctuations (expansion / shrinkage) of the pipe are absorbed by deformation of the inner wall of the furnace so as to be absorbed by the inner wall portion of the furnace made of platinum or a platinum alloy.

In this case, the thickness of the lining made of platinum or a platinum alloy constituting the bottom of the furnace or the side wall of the furnace in the vicinity of the bottom of the furnace, which constitutes the glass melting furnace, and the thickness of the outflow pipe, Made thinner than the thickness, so that the strength of the outflow pipe against deformation is substantially greater than the strength of the bottom of the 1000 km and the lining of the side walls,
By not fixing the part of the lining that is weak in strength,
It is preferable that the dimensional change due to the expansion and contraction of the furnace body and the outflow pipe due to heat can be concentrated on that portion. In addition, in order to suppress the position fluctuation due to the heat of the outflow pipe, particularly the nozzle port, the electrode terminal for conducting and heating the outflow pipe and the nozzle port is separated from the other inner wall members constituting the furnace body by the furnace. It is more effective to firmly fix to a positionally stable support member that is hardly affected by the temperature of the inside of the furnace, the outflow pipe, etc., which supports the molding related equipment such as the outer periphery and the glass receiving mold, etc. is there.

Therefore, the dimensional change due to the thermal expansion and contraction of the portion of the furnace body and the outflow pipe made of platinum or a platinum alloy can be concentrated on a required portion, whereby the position of the outflow nozzle port can be kept constant. , And the supply position of the molten glass to the forming die can be accurately secured without being affected by the temperature change on the furnace side.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION

(Embodiment 1) A first embodiment of the present invention is shown in FIG.
This will be specifically described with reference to FIG. Here, reference numeral 1a denotes a platinum lining member constituting an inner wall of the glass melting / refining tank 4 for melting raw materials of glass, and 1c denotes a glass stirring / outflow tank 5 for homogenizing molten glass. A platinum lining member 1b constituting the inner wall communicates with the glass melting / refining tank 4 and the glass stirring / outflow tank 5, and at the same time, a communication pipe 6 which also serves as a fining tank for fining fine bubbles in the molten glass. 1 shows a platinum lining member.

Further, reference numeral 1d designates a platinum lining member particularly stretched at the bottom of the glass stirring / outflow tank 5, and reference numeral 2 designates an outflow pipe made of platinum, and a tip nozzle which is a part thereof. The mouth is indicated by reference numeral 2a. In addition, these lining members may be made entirely or partially of a platinum alloy.

Reference numeral 11 denotes a glass stirring / outflow tank 5
, A stirring blade for controlling the stirring of the molten glass, 12 is a molten glass, 12a is an outflow glass flowing out from the nozzle port 2a, and 13 is an outflow glass 12
Indicates a receiving mold for receiving a. Heating members (not shown) are arranged around the outflow pipe 2, the glass melting / refining tank 4, the glass stirring / outflow tank 5, and the communication pipe 6, and each part is heated to a required temperature. Can be heated.

FIG. 2 shows a state of deformation due to thermal expansion when the glass melting furnace having such a configuration is operated. Here, at the time of heating for melting the glass, the location of the lining member 1d at the bottom of the glass stirring / outflow tank 5 is concentrated and greatly deformed. That is, the lining members 1a to 1d and the outflow pipe 2 are integrally formed so that molten glass does not leak out, and the lining member 1d shown in FIG. In comparison, its thickness is made thin. Further, among the lining members, as shown in FIG. 1, the lining member 1d is attached with a gap 20a to a refractory reinforcing member 3 provided outside the furnace body for supporting the entire lining member. ing. Similarly, the outflow pipe 2 is attached to the refractory reinforcing member 3 with a gap 20b except for the vicinity of the nozzle port 2a.

Therefore, when the lining member 1c and the outflow pipe 2, especially the latter, expands and contracts due to a temperature change, a deformation of the lining member 1d causes the nozzle opening 2a.
Is absorbed so as not to change the position (up and down, left and right position). Next, the production of an optical glass element using this glass melting furnace will be described more specifically.
In FIG. 1, a glass melting / refining tank 4, a glass stirring / outflow tank 5, and an outflow pipe 2 are each connected to 1,300
C., 1,100.degree. C., and 1,200.degree. C., and the glass material is supplied to the glass melting / refining tank 4, and in a molten state, the glass stirring / outflow tank 5 is sequentially passed through the connecting pipe 6. On the other hand, in the glass stirring / outflow tank 5, the molten glass is stirred by rotating the stirring blade 11 as indicated by the arrow in FIG. 1 simultaneously with the start of the glass melting. As a result, a homogeneous molten glass with good bubble elimination is discharged from the nozzle port 2a.

The outflow glass 12a is received by the receiving die 13, and is cut at predetermined intervals by a cutting blade (not shown) to form a glass block having a predetermined weight. Thereafter, the glass lump is carried under the upper die (not shown) of the press forming apparatus while being placed on the receiving die 13, and the receiving die 13 works as a lower die to be pressed and formed. An optical glass element having the shape of

When the temperature of the glass melting furnace is raised, the outflow pipe 2 expands vertically by about 2 mm. In the case of the structure of the conventional melting furnace, the position of the nozzle port 2a is changed every time the temperature rises.
The distance L shown in FIG. 1 becomes unstable, as well as the horizontal direction, that is, the distance L shown in FIG. 1 becomes unstable, and defects such as protrusion or wall thickness failure due to misalignment or excessive or insufficient weight of the molded glass element are caused. Many occurrences, reproducibility was not obtained in shape and weight, and good quality glass elements could not be obtained, but in the glass melting furnace according to the present invention, as shown in FIG. Thermal deformation concentrates on the portion of the lining member 1d, and causes thermal deformation as shown by reference numeral 1d 'in FIG.
As a result, the position of the nozzle port 2a was always stable, and an optical glass element having a very stable shape and weight could be obtained.

(Embodiment 2) A second embodiment of the present invention will be specifically described with reference to FIGS. In FIG. 3, reference numeral 101a denotes a material for melting glass raw materials.
Reference numeral 101b denotes a platinum lining member forming the upper portion of the glass melting tank 104 for refining and stirring, reference numeral 101b denotes a platinum lining member forming the bottom portion of the glass melting tank 104, and reference numeral 101c denotes a lining member 101a. , 101b shows a platinum lining member constituting a portion of the glass melting tank 104 at a point where the glass melting tank 104 is connected.

Reference numeral 102 denotes a glass melting tank 104.
Is a platinum outflow pipe attached to the lower part of the nozzle. The nozzle port 102a at the tip of the pipe is made of, for example, a platinum alloy. Electrode terminals 102b and 102c for direct current heating are attached to the outflow pipe 102. The electrode terminal 102b heats the nozzle port 102a, and the electrode terminal 102c heats the entire outflow pipe 102.
It is connected to power supply 115a and power supply 115b. Further, the power supplies 115a and 115b are controlled by a temperature controller (not shown), and the temperatures of the outlet pipe 102 and the nozzle port 102a are arbitrarily set and controlled by the temperature controller.
Controlled. As in the first embodiment, a heater (not shown) is arranged around the glass melting tank 104 so that a required temperature can be obtained.

Reference numeral 112 denotes molten glass, and reference numeral 1 denotes
Reference numeral 12a denotes outflow glass flowing out from the nozzle port 102a. Further, reference numeral 103 denotes a sheath crucible made of a refractory, which is attached to a fixed base (not shown), supports the lining members 101a and 101b from the outside, and further has a space between the lining member 101c and the lining member 101c. Is provided with a void 120 so that when the portion of the lining member 101c is deformed by thermal stress, it does not compete with each other.

The bottom 102b of the furnace is connected to a power supply 115a.
Is fixed firmly to the fixed base so as not to be affected by the fluctuation of the outflow pipe 102 and the glass melting tank 104 due to the heat when the lead wire 121 is connected to the lead wire 121. By operating the furnace having such a configuration, the lining member 101c is deformed as shown in FIG. This is the same as in the first embodiment. A glass raw material is put into the glass melting tank 104, the temperature of the glass melting tank 104 is first set to 1,300 ° C., and a molten glass 112 is obtained. After that, the temperature of the glass melting tank 104 is lowered to 1,100 ° C., and the molten glass 112 is clarified. For example, the molten glass 112 is stirred by a stirrer (not shown) to obtain a homogeneous molten glass with good bubble elimination. is there.

Next, the outflow pipes 102 and 102a were set at 1,000.degree. C. and 1,200.degree. C., respectively, and the molten glass was allowed to flow out, thereby producing an optical glass element in the same manner as in the first embodiment. Explain the results. Here, the heating of the crucible in the glass melting furnace was repeatedly performed, but the deformation of the crucible was limited to the deformation of the lining member 101c at the time of heating as shown in FIG. Not done.
That is, the structure of the present invention was found to be very effective in maintaining the shape of the crucible and maintaining the position of the nozzle port 102a and the nozzle shape.

[0026]

As described above, the present invention relates to a glass melting furnace for melting glass in a glass melting tank and flowing the molten glass out of the furnace through a glass outflow pipe. In order to suppress the reaction with the furnace material that constitutes the furnace, the inner wall of the furnace and the outflow pipe that are in direct contact with the molten glass are made of platinum or a platinum alloy, and the heat fluctuation (expansion / (Shrinkage) is absorbed by the inner wall portion of the furnace made of platinum or a platinum alloy, so that the inner wall portion of the furnace can be thermally deformed. Displacement of the nozzle opening at the tip and deformation of the nozzle shape can be reliably prevented, and problems caused by misalignment of the nozzle opening are eliminated, thereby producing a stable and highly efficient optical element. It became feasible.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a configuration of a furnace according to a first embodiment of the present invention.

FIG. 2 is a view showing a deformed state of the furnace during heating.

FIG. 3 is a diagram illustrating a configuration of a furnace according to a second embodiment of the present invention.

FIG. 4 is a view showing a deformed state of the furnace.

[Explanation of symbols]

 1a, 1b, 1c, 1d Furnace lining member 2 Furnace 2 Outflow pipe 2a Nozzle port 3 Reinforcing member 4 Glass melting / refining tank 5 Glass stirring / outflow tank 13 Receiving mold 101a, 101b, 101c Platinum lining member 102 Outflow pipe 102a Nozzle port 102b, 102c Electrode for direct current supply 103 Sheath crucible 104 Glass melting tank

Claims (3)

[Claims] 1. A method for melting glass in a glass melting tank, flowing the molten glass out of the furnace through a glass outflow pipe, and suppressing a reaction between the glass and a furnace material constituting the furnace. In a glass melting furnace in which the inner wall and outflow pipe of the furnace, which are in direct contact with the molten glass, are made of platinum or a platinum alloy, heat fluctuation (expansion / shrinkage) of the outflow pipe caused by heat is reduced by the platinum or platinum alloy. A glass melting furnace characterized in that absorption is performed by deformation of an inner wall of the furnace so as to be absorbed by an inner wall portion of the furnace constituted by: 2. The strength of each part is set so that the bottom of the furnace or the side wall of the furnace connected to the outflow pipe is partially weaker than the outflow pipe. The glass melting furnace as described. 3. The glass melting furnace according to claim 1, wherein the supporting member for supporting and fixing the outflow pipe uses a lead plate of an electrode for direct current heating attached to a tip of the pipe. .