JP3363716B2 - Temperature measurement device for mold members that mold and process glass molded products - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hot working (heat treatment) apparatus for measuring and controlling a temperature by a thermocouple. In particular, the present invention can be expected to have a remarkable effect on a temperature measuring apparatus and a temperature measuring method for forming a glass material such as a lens, a prism, a mirror, etc. by heating and pressing a glass material into a predetermined shape. It is an invention. [0003] FIG. 3 is a typical diagram showing a case where the temperature inside a solid is measured by a thermocouple. In the figure, 101 is a thermocouple, 102 is an object to be measured, and 103 is a hole for inserting a thermocouple. In temperature measurement inside a solid, the transfer of heat to a thermocouple is performed mainly by conduction. Therefore, it is important to improve the contact between the thermocouple and the hole of the object to be measured. As a device for this purpose, (1) filling the gap between the thermocouple and the insertion hole with a substance having good heat conductivity; (2) Means for sufficiently increasing the insertion length of the thermocouple, or making the insertion hole diameter severe. However, practically, it is often difficult to employ the above-mentioned means (1) and (2). First, when it is necessary to replace or set up the object to be measured, the filling method described in (1) above requires maintenance of the filler every time the thermocouple is attached and detached, which is efficient in terms of time and economy. bad. In addition, the filler may cause a defective product. When the object to be measured is small, it is impossible to make the insertion length of the thermocouple (2) sufficiently long. There is also a limit in making the insertion hole diameter severe, and if the tip of the thermocouple is bent without proper clearance, the thermocouple cannot be mounted. [0006] In particular, when measuring the temperature under vacuum, the influence of the above-mentioned clearance appears remarkably. This is because, under the atmosphere or under an inert gas, since a gas layer exists in the clearance, heat conduction by the gas compensates for the temperature error of poor contact. As a phenomenon of temperature measurement under vacuum, there is a problem that the thermocouple of the temperature measurement section shows a value considerably lower than the actual temperature. In addition, the variation in the clearance becomes a temperature variation as it is, which may cause a product defect in a process requiring high-precision temperature control. Therefore, the present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide a method for measuring the temperature inside a solid with high accuracy. Further, the present invention relates to a temperature suitable for temperature measurement of an apparatus for forming a glass molded article by heating and pressing a glass material to form a glass molded article, for example, a processing apparatus for press-molding a glass molded article such as a glass lens, a prism and a mirror. It is to propose a measuring device. Further, the present invention relates to a method for forming a glass, which comprises measuring the temperature of the glass material when processing the glass material by heating and pressing the glass material, including high-precision measurement. It is to propose. [0010] In order to solve the above-mentioned problems and achieve the object, a temperature measuring apparatus of the present invention heats and presses a glass material under vacuum to form a glass molded product. A temperature measuring device for a mold member, wherein the mold member is made of a cemented carbide material, a hole for temperature measurement is provided in the mold member, and a material having a coefficient of thermal expansion higher than the coefficient of thermal expansion of the mold member. The sheath of the thermocouple is inserted into and fixed to the cylindrical member, and the cylindrical member is inserted into the temperature measurement hole,
When the mold member is heated to the molding temperature of the glass material, the dimension of the gap between the temperature measurement hole and the cylindrical member is set so that the cylindrical member is in close contact with the wall surface of the temperature measurement hole. Features. Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 is a view showing a mold for an optical element. This is a method of forming a high-precision optical element such as an aspherical lens by pressing a heat-softened glass material with a pair of upper and lower forming mold members, and controlling the temperature of the forming mold with high precision. I need. In the figures, reference numerals 1 and 2 denote an upper mold and a lower mold having optical functional surfaces on opposite sides. Reference numerals 3 and 4 denote heaters, and reference numerals 5 and 6 denote press shafts having a driving source (not shown) for driving up and down. 7 is a glass material, and 8 and 9 are holes provided in the molds 1 and 2, respectively. Numerals 10 and 11 denote thermocouple units having a high thermal expansion member fixed to the tip, which will be described in more detail with reference to FIG. In the figure, reference numeral 20 denotes a K type thermocouple having a diameter of 1.0 mm. The sheath is made of stainless steel. Reference numeral 21 denotes a cylindrical member made of stainless steel, and has a through hole that is finished with high precision so that 20 thermocouples can be inserted into the center. At both ends, twenty thermocouples are fixed by welding. Of course, this fixing method may use an appropriate adhesive. Next, the relationship between the holes 8 and 9 provided in the upper mold 1 and the lower mold 2 and the diameter of the cylindrical member 21 will be described. The upper and lower dies 1 and 2 are made of cemented carbide and have a coefficient of thermal expansion of 5.
5 × 10 ⁻⁶ / ° C. Moreover, that of the cylindrical member 21 is 1
8 × 10 ⁻⁶ / ° C. In this embodiment, since the molding is performed at 580 ° C., each diameter is set in consideration of this temperature range. That is, the diameter of the holes 8 and 9 is φ5.0 mm, and at the forming temperature, φ5.015
mm. Accordingly, the cylindrical member has a diameter of 5.01 in the molding temperature range.
In order to closely fit the hole of 5 mm, the diameter of the cylindrical member may be calculated to be 4.966 mm from the coefficient of thermal expansion. Hole diameter is φ
5.015 mm, the diameter of the cylindrical member is 4.966 mm, and the difference (clearance) between the two is 49 μm. Therefore, the thermocouple units 10 and 11 can be easily attached and detached during setup change. The length of the cylindrical member is 8 mm. Assuming that the cylindrical member is not used, the coefficient of thermal expansion of the thermocouple is 18 × 10 ^{−6 /} ° C., φ1.0 m
The m thermocouple has a molding temperature of φ1.01 mm. In order to make close contact with the holes 8 and 9 of the upper and lower dies 1 and 2 at the molding temperature, the hole diameter is
Similarly, the reverse calculation is performed to obtain φ1.007 mm. Thermocouple diameter φ1.0mm and hole diameter φ1.007
mm has a difference (clearance) of only 7 μm, which makes it very difficult to attach and detach the thermocouple. φ1.0
mm or φ1.6mm thermocouple is easy to bend,
The clearance requires at least 0.1 mm. However, since molding is performed under vacuum,
If a clearance of m is taken, a temperature error occurs as described in the above-mentioned [Problems to be Solved by the Invention].
In the actual test results, 5 to 5
The temperature was measured as low as 10 ° C. In the molding of the optical element using the temperature measuring method constituted in the present invention, it is possible to measure the temperature almost equal to the actual temperature even under vacuum, so that it is possible to control the temperature with high precision and to produce a high quality optical element. Became possible. As a specific molding example, a result of molding a diffraction grating will be described. When a diffraction grating or a prism is formed, defects such as residual gas of the forming atmosphere gas are likely to occur on the transfer surface of the formed product. First, a conventional temperature measurement method (φ
Drill a 1.1mm hole and place a φ1.0mm thermocouple there.
Insert ). Eleven of the 20 molded products were defective due to fusion, cracking, and poor surface transfer. However, when the measurement was performed using the temperature measuring device and the measuring method according to the present invention, no defect due to a temperature defect was found at all, and all 70 molded products were non-defective. The present invention can be applied to a modification or a modification of the above embodiment without departing from the spirit thereof.
And it is applicable also to other hot working devices. As described above, according to the temperature measuring method of the present invention, the hole of the member to be measured and the member at the tip of the thermocouple are brought into close contact with each other due to the difference in thermal expansion in the operating temperature range. This has the effect of performing the temperature measurement with extremely high accuracy. Further, in the temperature measuring device of the glass forming apparatus, a hole for temperature measurement is provided in a mold member for forming and processing the heated glass material, and a thermocouple of the measuring means has a higher thermal expansion coefficient than the material of the mold member. By attaching an intermediate member having a coefficient of thermal expansion and fixing the thermocouple to the temperature measurement hole of the mold member via the intermediate member, it was possible to provide an apparatus capable of measuring the temperature of the glass material to be processed with higher accuracy. . Further, according to the present invention, a temperature measuring hole is provided in a mold member for forming and processing a glass material, and an intermediate member having a thermal expansion coefficient higher than the thermal expansion coefficient of the mold member is fixed to a thermocouple. With the thermocouple inserted into the temperature measurement hole, the temperature of the mold member reaches the processing temperature of the glass material, the intermediate member and the peripheral surface of the temperature measurement hole of the mold member Proposal of a method for measuring the temperature of a glass molded article in which the contact state is maintained could improve the molding accuracy of the glass molded article. For example, when the above glass material is heated and pressed in a mold member to transfer the transfer surface shape of the mold member to form an optical product such as a lens, a prism, a mirror, etc. Therefore, the glass material and the glass composition component adhere to the transfer surface of the mold member due to the high temperature and high pressure, and it is necessary to remove the attached matter. Therefore, maintenance repair is performed in the cycle of the forming process, but the present invention is excellent in workability of maintenance.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagram showing a configuration of an embodiment of a temperature measuring method according to the present invention. FIG. 2 is an enlarged view of a temperature measuring unit in FIG. FIG. 3 is a diagram showing a conventional temperature measuring method. [Description of Signs] 8, 9 Holes 20 provided in upper and lower dies 1, 2 Thermocouple 21 Cylindrical part

Continuation of the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G01K 1/14-1/16 G01K 7/02 C03B 11/00-11/12

Claims (1)

(1) A temperature measuring device for a mold member for forming a glass molded product by heating and pressing a glass material under vacuum, wherein the mold member is made of a cemented carbide material. The mold member is provided with a hole for temperature measurement, a sheath portion of a thermocouple is inserted and fixed to a cylindrical member made of a material having a higher thermal expansion coefficient than the thermal expansion coefficient of the mold member, and the cylindrical member is The temperature measurement hole and the cylinder are inserted into the temperature measurement hole and when the mold member is heated to the molding temperature of the glass material, the cylindrical member is in close contact with the wall surface of the temperature measurement hole. A temperature measuring device for a mold member for forming and processing a glass molded product, wherein a dimension of a gap between members is set.