Method for manufacturing a melt molding apparatus and a vibrator

Abstract

To provide a melting-molding device for a vibrator.SOLUTION: A melting-molding device comprises a melting-molding tool having a flat upper surface, and a hole part formed on a portion of the upper surface around a central axis perpendicular to the upper surface. The melting-molding device comprises a burner disposed above the central axis, having a burner tip part disposed facing the hole part, and configured to be able to generate flame toward the hole part from the burner tip part. The melting-molding device comprises a flame position control part for controlling a frame position in a movable manner in the plane direction in parallel to the upper surface.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] This specification relates to a melt molding apparatus for a vibrator and a manufacturing method thereof.

Background Art

[0002] Patent Document 1 discloses a Bird-bath Resonator Gyroscope (BRG) using fused silica as a vibrator, which enables high precision. Specifically, a melt molding die having a hole formed in a part of the upper surface is prepared. The hole is formed in a part of the upper surface around a central axis perpendicular to the upper surface of the molding die. A workpiece (e.g., a quartz plate) is placed so as to close the hole, the lower surface of the workpiece is decompressed, and the upper surface of the workpiece is heated with a burner. By melting and deforming the workpiece so as to enter the inside of the hole, a hemispherical vibrator can be produced.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In order to produce a vibrator having high symmetry with respect to the central axis of the hole, it is necessary to input heat with a concentric temperature distribution with respect to the central axis of the hole. However, since the temperature distribution of the flame has asymmetry with respect to the central axis, it is difficult to produce a vibrator having high symmetry.

Means for Solving the Problems

[0005] The melt molding apparatus disclosed herein includes a melt molding die having a flat top surface and a hole formed in a part of the top surface with respect to a central axis perpendicular to the top surface. The melt molding apparatus includes a burner having a burner tip positioned above the central axis and facing the hole, and configured to generate a flame from the burner tip toward the hole. The melt molding apparatus includes a flame position control unit that controls the position of the flame so as to be movable in a planar direction parallel to the top surface.

[0006] In the above configuration, the position of the flame can be moved in a planar direction parallel to the top surface. This improves the asymmetry of the flame temperature distribution with respect to the central axis. Since heat can be input with a temperature distribution concentric with respect to the central axis, it becomes possible to fabricate an oscillator with high symmetry.

[0007] The flame position control unit may control the position of the burner tip in the planar direction so as to be movable while maintaining a substantially constant distance between the burner tip and the upper surface. Details of the effects will be explained in the examples.

[0008] The flame position control unit may include three or more electrodes arranged rotationally symmetrically around a central axis, surrounding the flame. The flame position control unit may also control the position of the flame in the planar direction so as to be movable by the electric field generated between the three or more electrodes. Details of the effects will be described in the examples.

[0009] The flame position control unit may be configured to apply either a voltage of a first polarity or a voltage of a second polarity opposite to the first polarity to each of three or more electrodes. The flame position control unit may also be controlled to change which electrode receives the voltage of the first polarity. Details of the effects will be described in the examples.

[0010] The flame position control unit may be configured to move the flame's position in the planar direction along a rotationally symmetrical trajectory around a central axis. Details of the effects will be described in the examples.

[0011] The flame position control unit may include multiple electrode pairs arranged symmetrically with respect to the central axis around the flame. The flame position control unit may be configured to apply either a voltage of a first polarity or a voltage of a second polarity opposite to the first polarity to each of the multiple electrode pairs. Details of the effects will be described in the examples.

[0012] The flame position control unit may be controlled to change the electrode pair to which the voltage of the first polarity is applied. Details of the effects will be described in the examples.

[0013] The temperature sensor for measuring the temperature of a melt molding die may further include a temperature sensor configured to measure the temperature at three or more measurement points arranged rotationally symmetrically around a central axis around the hole. The flame position control unit may be configured to control the position of the flame in the planar direction so as to reduce the temperature difference between the three or more measurement points. Details of the effects will be described in the examples.

[0014] One embodiment of a method for manufacturing a vibrator disclosed herein is a method for manufacturing a vibrator using a melt molding apparatus comprising: a melt molding die having a flat upper surface and a hole formed in a part of the upper surface with respect to a central axis perpendicular to the upper surface; a burner having a burner tip positioned above the central axis and facing the hole, and configured to generate a flame from the burner tip toward the hole; and a flame position control unit that controls the position of the flame so as to be movable in a planar direction parallel to the upper surface. The method for manufacturing a vibrator includes an arrangement step of arranging a plate-shaped workpiece on the upper surface so as to cover the hole. The method for manufacturing a vibrator includes a step of generating a flame from the burner tip. The method for manufacturing a vibrator includes a heating step of heating the workpiece with the flame while moving the position of the flame by the flame position control unit while generating negative pressure in the hole. Details of the effects will be described in the examples. [Brief explanation of the drawing]

[0015] [Figure 1] This is a schematic cross-sectional view of the melt molding apparatus 1 of Example 1. [Figure 2] It is a top view of the melt molding apparatus 1 of Example 1. [Figure 3] It is a flowchart for explaining the manufacturing process of the vibrator. [Figure 4] It is a diagram showing an example of the movement locus TR1 of the burner center axis BA. [Figure 5] It is a perspective view showing a modification of Example 1. [Figure 6] It is a cross-sectional side view of the melt molding apparatus 201 of Example 2. [Figure 7] It is a cross-sectional top view of the melt molding apparatus 201 of Example 2. [Figure 8] It is a diagram showing the movement mode of the flame FL. [Figure 9] It is a diagram showing the change in the shape of the flame FL. [Figure 10] It is a cross-sectional side view showing the first modification of Example 2. [Figure 11] It is a cross-sectional side view showing the second modification of Example 2. [Figure 12] It is a cross-sectional side view showing the third modification of Example 2. [Figure 13] It is a top view of the melt molding apparatus 3 of Example 3.

Mode for Carrying Out the Invention

Examples

[0016] (Configuration of the melt molding apparatus 1) FIG. 1 shows a schematic cross-sectional view of the melt molding apparatus 1. FIG. 2 shows a top view of the melt molding apparatus 1. FIG. 1 corresponds to the cross-sectional view taken along line I-I of FIG. 2. In FIG. 2, the description of the burner 50, the movable mechanism 53, and the electric stage 45 is omitted.

[0017] The electric stage 45 is configured to be movable in the xy direction (horizontal direction). The electric stage 45 includes a flat mounting surface 45s. On the mounting surface 45s, the molding die 20 is mounted via the heat sink 40 and the plate 10.

[0018] The heat sink 40 is positioned between the electric stage 45 and the mold 20. The heat sink 40 is in contact with the lower surface 10r of the plate 10. A circulation pipe 41 is located inside the heat sink 40. The circulation pipe 41 is connected to a chiller system 42. A heat transfer medium, kept at a constant temperature (e.g., 35°C) by the chiller system 42, circulates through the circulation pipe 41. This allows the heat sink 40 to maintain a constant temperature throughout the process.

[0019] The plate 10 is placed on the heat sink 40. The plate 10 is a stainless steel stand for mounting the mold 20. The plate 10 has the function of cooling the mold 20. A first connecting hole 10c1 is formed on the surface 10s of the plate 10. The first connecting hole 10c1 is positioned corresponding to the through hole 20e and is connected to the through hole 20e. The first connecting hole 10c1 is connected to a negative pressure generating means 81 via a first connecting passage 10p1. The negative pressure generating means 81 is a means capable of generating negative pressure in the hole 20h. The negative pressure generating means 81 may be, for example, a vacuum pump.

[0020] The mold 20 is placed on the surface 10s of the plate 10. The mold 20 is a mold for forming a hemispherical vibrator by melting and deforming the quartz plate 30. The material of the mold 20 is graphite. In this embodiment, the mold 20 is a disc shape with a central axis CA. The mold 20 comprises a lower surface 20r, an upper surface 20s, a hole 20h, a support column 20p, and a through hole 20e. The lower surface 20r and the upper surface 20s are flat surfaces perpendicular to the central axis CA. A hole 20h is formed in a part of the upper surface 20s. The hole 20h is a deformation space for the quartz plate 30 to melt and deform. In this embodiment, the hole 20h has a cylindrical shape hollowed out with the central axis CA as the center. The hole 20h has a bottom surface 20b. A support column 20p is positioned in the center of the hole 20h, extending vertically upward from the bottom surface 20b. The support column 20p is a cylinder with central axis CA as its central axis. The bottom surface 20b has multiple through holes 20e that penetrate through to the bottom surface 20r. The through holes 20e are in communication with the first connecting hole 10c1.

[0021] A quartz plate 30 is positioned on the upper surface 20s of the mold 20 so as to cover the hole 20h. The quartz plate 30 is the material to be processed for forming the oscillator. The quartz plate 30 is made of fused silica. The thickness of the quartz plate 30 is, for example, 100 μm or less. In this embodiment, the quartz plate 30 is square, but it may also be circular or a regular hexagon.

[0022] The burner 50 is positioned above the central axis CA. The burner 50 comprises a premixing chamber 50c, a tube 50t, and a burner tip 50s. Fuel gas G1 (e.g., propane) and oxygen gas G2 are supplied to the premixing chamber 50c from a gas flow regulator 52. The gas flow regulator 52 includes a mass flow controller (not shown) that can control and monitor the flow rates of fuel gas G1 and oxygen gas G2. The tube 50t extends downward from the premixing chamber 50c. The tube 50t is a cylindrical member having a burner central axis BA extending vertically. At the lower end of the tube 50t is the burner tip 50s, which faces the hole 20h. By generating a flame from the burner tip 50s toward the hole 20h, the quartz plate 30 can be heated.

[0023] The burner 50 is fixed to the movable mechanism 53. The movable mechanism 53 is a mechanism that can move in the vertical direction (±z direction) and in the xy plane parallel to the upper surface 20s. The movable mechanism 53 can move the burner tip 50s up and down along the central axis CA. The movable mechanism 53 can also move the position of the burner tip 50s in the two-dimensional xy plane while maintaining a substantially constant distance between the burner tip 50s and the upper surface 20s.

[0024] The control unit 70 is connected to the electric stage 45, the movable mechanism 53, the gas flow regulator 52, and the negative pressure generating means 81. The control unit 70 acquires various information from these devices and controls them. The control unit 70 may be, for example, a PC.

[0025] (Manufacturing process for oscillators) The manufacturing process of the oscillator will be explained using the flowchart in Figure 3. In step S10, the heat sink 40 is kept at a constant temperature by continuously circulating the heat transfer medium from the chiller equipment 42 to the circulation piping 41. A molding die 20 is also placed on the surface 10s of the plate 10.

[0026] In step S20, the quartz plate 30 is placed on the upper surface 20s of the mold 20. At this time, it is positioned so that the center axis CA and the center of the quartz plate 30 coincide. Based on a signal from the control unit 70, the negative pressure generating means 81 performs vacuuming of the first connecting hole 10c1. As a result, the hole portion 20h is also vacuumed through the through hole 20e, and the quartz plate 30 is adsorbed and fixed to the upper surface 20s of the mold 20. This results in the state shown in Figures 1 and 2.

[0027] In step S30, the control unit 70 ignites the burner 50. Ignition is performed in a retracted position where the burner tip 50s is sufficiently far from the surface of the quartz plate 30.

[0028] In step S40, the control unit 70 controls the movable mechanism 53 to move the position of the burner tip 50s in the two-dimensional xy plane. The movement trajectory is rotationally symmetric about the central axis CA and is a single-stroke trajectory. It is preferable that the period for one revolution of the trajectory is sufficiently short compared to the processing time required for the melting deformation of the quartz plate 30. For example, if the processing time is about 10 to 20 seconds, it is preferable that the period for one revolution of the trajectory is a few seconds or less. This makes it possible to input heat with a concentric temperature distribution with respect to the central axis CA.

[0029] The trajectory of the movement can vary. The trajectory may be selected to match the asymmetry of the temperature distribution of the burner 50. For example, the trajectory may be a circle, a trochoid curve, a vector scan of a polygon or n-pointed star, or a raster scan. By appropriately selecting the trajectory, the effect of improving the symmetry of the temperature distribution can be obtained. Figure 4 shows an example of the movement trajectory TR1 of the burner central axis BA at the burner tip 50s. The movement trajectory TR1 in Figure 4 is a type of internal trochoid curve.

[0030] In step S50, the control unit 70 lowers the burner 50 by controlling the movable mechanism 53, thereby reducing the distance between the burner tip 50s and the quartz plate 30. This initiates the heating process of the quartz plate 30 by the flame.

[0031] The timing of when the descent begins, and the distance between the burner tip 50s and the quartz plate 30, can be controlled in various ways. For example, the descent may begin after a predetermined time has elapsed since the burner 50 was ignited in step S30, and stop when the burner tip 50s and the quartz plate 30 approach a predetermined distance. Alternatively, for example, the temperature of the support column 20p may be measured with a radiation thermometer (not shown), and the descent timing and the distance between the burner tip 50s and the quartz plate 30 may be determined by temperature feedback control.

[0032] A distributed load is applied to the quartz plate 30 due to the pressure difference between atmospheric pressure and the negative pressure inside the hole 20h. Therefore, as the quartz plate 30 is heated to its softening temperature, it can be melted and deformed so that it enters the hole 20h. If it is determined in step S60 that the melting and deformation of the quartz plate 30 is complete (S60:YES), the process proceeds to step S70. There are various methods for detecting the end of the processing. For example, the end of processing may be detected after a predetermined processing time has elapsed since the burner 50 was lowered in step S50.

[0033] In step S70, the control unit 70 controls the movable mechanism 53 to raise the burner 50. Then, as it moves to the retracted position, it stops rising and extinguishes the flame. In step S80, the control unit 70 controls the movable mechanism 53 to stop the movement of the burner tip 50s in the xy plane.

[0034] In step S90, the control unit 70 waits for the cooling to be completed. Once cooling is complete, the control unit 70 stops the negative pressure generating means 81. This opens the hole 20h to the atmosphere. In step S100, the molten quartz plate 30 is removed from the mold 20. The oscillator is completed by removing the unformed area on the outer circumference of the quartz plate 30 using methods such as CMP or laser cutting.

[0035] (assignment) To fabricate an oscillator with high symmetry with respect to the central axis CA of the hole 20h, it is necessary to input heat from the burner 50 with a temperature distribution concentric with respect to the central axis CA. However, since the temperature distribution of the flame is asymmetrical with respect to the central axis CA, it is difficult to fabricate an oscillator with high symmetry.

[0036] Conventionally, there was a technique to suppress the asymmetry of the flame temperature distribution by rotating the mold 20, which holds the quartz plate 30 in place, around a central axis CA. However, this conventional technique requires rotating the plate 10 installed below the mold 20. The plate 10 needs to have a large heat capacity to improve the controllability and uniformity of heat dissipation, and is therefore heavy. Consequently, there were problems such as the rotation mechanism becoming large. In addition, since it is necessary to rotate while reducing the pressure in the hole 20h, the airtightness of the rotating sliding parts needs to be improved. Consequently, there was a problem that the entire device became expensive. Furthermore, in the conventional technique, centrifugal force due to rotation is applied to the quartz plate 30 during processing. If the suction force of the quartz plate 30 due to the negative pressure in the hole 20h decreases due to deterioration of the mold 20 or leakage due to melting fracture of the quartz plate 30 during processing, there is a risk that the quartz plate 30 will detach and scatter, which was a problem.

[0037] Another possible method to improve the asymmetry of the flame temperature distribution is to rotate the burner 50 around the burner central axis BA. However, since the fuel gas G1 piping is connected to the burner 50, there is a risk of the piping coming loose or gas leaking, which is problematic. Another possible method is to repeatedly rotate (pulsate) the burner 50 ±180 degrees around the burner central axis BA. However, since the rotation speed is accelerated or decelerated when reversing the rotation, it is difficult to improve the uniformity of the flame temperature distribution, which is problematic.

[0038] (effect) In the melt molding apparatus 1 of Example 1, the position of the burner tip 50s can be moved in the xy plane along a rotationally symmetrical trajectory around the central axis CA. This makes it possible to achieve a wide heat input with a concentric temperature distribution around the central axis CA, resulting in a highly symmetric oscillator.

[0039] In the melt molding apparatus 1 of this embodiment, the symmetry of the flame temperature distribution can be improved without rotating the plate 10. Therefore, it is possible to suppress the increase in size and cost of the apparatus. In addition, even if the adsorption force of the quartz plate 30 decreases, the quartz plate 30 will not be scattered.

[0040] In the melt molding apparatus 1 of this embodiment, the symmetry of the flame temperature distribution can be improved without rotating the burner 50 around the burner central axis BA. Therefore, the risk of pipes coming loose or gas leaks occurring can be suppressed.

[0041] (Modified version of Example 1) The mechanism for moving the position of the burner tip 50s in the xy plane is not limited to the movable mechanism 53, but can be any of the various mechanisms. For example, as shown in the perspective view of Figure 5, a pivot support point 50r that can rotate 360° may be provided on the top of the burner 50. The burner's central axis BA may then be swung around the pivot support point 50r by a mechanism not shown. This allows the position of the burner tip 50s to be moved by an action called a pestle-like motion.

[0042] Furthermore, since the area where the grinding motion is performed can be small, the inclination angle of the burner's central axis BA with respect to the central axis CA can be kept small, at 10° or less. Consequently, the variation in the distance between the burner tip 50s and the quartz plate 30 due to the inclination of the burner 50 is negligibly small, and therefore there is no problem in terms of heat input uniformity. [Examples]

[0043] (Configuration of the melt molding apparatus 201) Figure 6 shows a cross-sectional side view of the melt molding apparatus 201 of Example 2. Figure 7 shows a cross-sectional top view of the melt molding apparatus 201 of Example 2. Figure 7 corresponds to the cross-sectional view along line VII-VII in Figure 6. Note that in Figure 6, the heat sink 40 and the electric stage 45 are omitted from the description, and only the vicinity of the burner tip 50s is shown. Example 2 differs from Example 1 in that it is equipped with electrodes 261 to 264. Parts common to the melt molding apparatus 1 of Example 1 are given the same reference numerals, and their explanation is omitted. Parts unique to Example 2 are distinguished by the use of reference numerals in the 200s.

[0044] Electrodes 261-264 are arranged by a holding mechanism (not shown) that surrounds the area where the flame FL is generated. Electrodes 261-264 are arranged rotationally symmetrically about the central axis CA. Electrodes 261 and 263, and electrodes 262 and 264 form electrode pairs that are arranged symmetrically with respect to the central axis CA. Each of electrodes 261-264 is connected to a control unit 70. The control unit 70 is configured to apply either a negative voltage or a positive voltage to each of electrodes 261-264.

[0045] (Controlling the movement of flames) Because flames contain positive ions, they are attracted to electrodes to which a negative voltage is applied. Therefore, by applying a negative voltage to an electrode located in the direction in which you want to move the flame, it becomes possible to move the flame in the xy-plane.

[0046] Figures 8(A) to 8(D) illustrate the case where the tip of the flame FL moves along a circular trajectory. Figure 8 is similar to the cross-sectional top view in Figure 7. As shown in Figure 8(A), when a negative voltage is applied to electrode 261 and positive voltages are applied to electrodes 262 to 264, the flame FL moves in the direction of electrode 261 (+x direction). Next, as shown in Figure 8(B), when a negative voltage is applied to electrode 262 and positive voltages are applied to electrodes 261, 263, and 264, the flame FL moves in the direction of electrode 262 (-y direction). Similarly, as shown in Figure 8(C), when a negative voltage is applied only to electrode 263, the flame FL moves in the direction of electrode 263 (-x direction). As shown in Figure 8(D), when a negative voltage is applied only to electrode 264, the flame FL moves in the direction of electrode 264 (+y direction). By continuously switching the electrodes to which negative voltage is applied in the order shown in Figures 8(A) to (D), it becomes possible to move the tip of the flame FL along a circular trajectory TR201 centered on the central axis CA.

[0047] Furthermore, by appropriately adjusting the switching control of the electrodes to which negative voltage is applied, various trajectories such as trochoid curves can be formed.

[0048] (Controlling the shape of the flame) By applying a negative voltage to both opposing electrodes, it becomes possible to stretch the cross-sectional shape of the flame in the xy-plane. This will be explained using the examples in Figures 9(A) and 9(B). As shown in Figure 9(A), by applying a negative voltage to the pair of electrodes 261 and 263 and a positive voltage to the pair of electrodes 262 and 264, the cross-sectional shape of the flame FL can be stretched in the x-direction. Similarly, as shown in Figure 9(B), by applying a negative voltage to the pair of electrodes 262 and 264 and a positive voltage to the pair of electrodes 261 and 263, the cross-sectional shape of the flame FL can be stretched in the y-direction. By continuously switching between the states shown in Figures 9(A) and 9(B), it becomes possible to change the cross-sectional shape of the tip of the flame FL in a rotationally symmetric shape around the central axis CA.

[0049] (effect) In the melt molding apparatus 201 of Example 2, the flame can be moved by an electric field. Since the flame movement mechanism does not require mechanical moving parts, failures due to wear or foreign matter jamming do not occur. This makes it possible to improve the reliability of the flame movement mechanism.

[0050] In a configuration where the burner 50 is driven mechanically, it is difficult to increase the drive frequency when the moment of inertia of the driven member is large. On the other hand, in the electric field drive of Embodiment 2, there is no problem with the moment of inertia, so the drive frequency can be freely set.

[0051] (First modified example of Example 2) The shape, structure, and arrangement of the electrodes can vary. For example, as shown in Figure 10, they may be divided in the height direction (z direction). Electrode 261a comprises an upper electrode 261U and a lower electrode 261L. Similarly, electrode 263a comprises an upper electrode 263U and a lower electrode 263L. A stronger negative voltage may be applied to the lower electrode 261L than to the upper electrode 261U. This allows a stronger electric field to be applied to the underside of the flame FL. The tip of the flame FL can be moved more significantly towards the lower electrode 261L (see region R1).

[0052] Furthermore, the electrode placement is not limited to a configuration perpendicular to the upper surface 20s of the mold 20. As shown in Figure 10, the electrodes may be tilted so that the distance from the central axis CA increases as you move downwards (towards the -z direction). The effects are explained below. The amount of movement of the flame FL in the xy plane is zero at the burner tip 50s and increases as you move downwards. Therefore, by tilting the electrodes so that the distance from the central axis CA increases as you move downwards, it is possible to prevent the tip of the flame FL from coming into contact with the electrodes (see region R1). This makes it possible to increase the durability of the electrodes.

[0053] Furthermore, the cross-sectional shape of the electrode is not limited to a straight line. As shown in Figure 10, it may be bent so that the distance from the central axis CA increases as it goes downwards. This allows the bend of the electrode to match the bend of the flame FL. When the flame FL is attracted to the electrode, the distance between the flame FL and the electrode can be kept constant in the height direction of the electrode (see region R2). The distance between the electrodes can be minimized while preventing the flame FL from coming into contact with the electrode. Since the distance between the electrodes is proportional to the strength of the electric field, it becomes possible to move the flame more significantly.

[0054] (Second variation of Example 2) The manner in which the electric field is applied can vary. An electric field may be generated by applying a voltage to a component other than the electrodes. For example, as shown in Figure 11, the control unit 70 may be configured to apply a mold voltage MV to the mold 20. By applying a positive mold voltage MV to the mold 20 and a negative voltage to electrodes 261a and 263a, an electric field EF can be generated from the mold 20 to electrodes 261a and 263a. Thus, the tip of the flame FL can be spread toward electrodes 261a and 263a (see region R3).

[0055] The manner in which voltage is applied to the mold 20 can vary. For example, a negative DC voltage may be applied. This makes it possible to maintain the tip of the flame FL in an expanded state. Alternatively, for example, an AC voltage may be applied. This makes it possible to periodically vary the width of the tip of the flame FL, causing it to expand and contract.

[0056] (Third modification of Example 2) The electrode materials can vary. For example, as shown in Figure 12, the inner surfaces 261i and 263i facing the flame FL side may be made of an insulator, and the outer surfaces 261o and 263o may be made of a conductor. The insulator is preferably heat-resistant, and alumina is a suitable material. The conductor is also preferably heat-resistant, and SUS is a suitable material.

[0057] Since the flame FL is a plasma, its dielectric strength is lower than that of ordinary air. Therefore, discharge can occur between electrodes via the flame FL, which can reduce the electric field strength. By placing insulators on the inner surfaces 261i and 263i, discharge between electrodes can be suppressed, thereby preventing a decrease in electric field strength. [Examples]

[0058] (Configuration of the melt molding apparatus 301) Figure 13 shows a top view of the melt molding apparatus 301 of Example 3. Example 3 differs from Example 1 in that it uses radiation thermometers 361-363. Parts common to the melt molding apparatus 1 of Example 1 are given the same reference numerals, and their explanation is omitted. Parts unique to Example 3 are distinguished by using reference numerals in the 300s.

[0059] The infrared thermometers 361-363 are non-contact temperature sensors. The infrared thermometers 361-363 are positioned above the upper surface 20s, corresponding to each of the measurement points 361m-363m, by a fixing mechanism (not shown). The focus of each infrared thermometer 361-363 is aligned to the measurement points 361m-363m. The infrared thermometers 361-363 transmit light through the transparent quartz plate 30 and are focused on the upper surface 20s of the mold 20. This allows for non-contact measurement of the temperature of the upper surface 20s at the measurement points 361m-363m. It also allows for indirect measurement of the temperature of the quartz plate 30.

[0060] Measurement points 361m to 363m are located on the circumference CR centered on the central axis CA. The circumference CR is a concentric circle surrounding the outer circumference of the hole 20h. In other words, measurement points 361m to 363m are arranged with 120° rotational symmetry around the central axis CA.

[0061] (Action and effect) During the heating process in step S50, the control unit 70 performs feedback control on the position of the burner tip 50s in the xy plane so that the temperature difference between the measurement points 361m and 363m is reduced. This makes it possible to make the heat input temperature distribution a perfect circle with respect to the central axis CA. This makes it possible to fabricate an oscillator with higher symmetry.

[0062] Although specific examples of the present invention have been described in detail above, these are merely illustrative and do not limit the scope of the claims. The technologies described in the claims include various modifications and changes to the specific examples illustrated above.

[0063] (modified version) In Example 2, the case with four electrodes was described, but the configuration is not limited to this. The electrodes only need to be arranged rotationally symmetrically around the central axis CA; for example, there could be three electrodes, or five or more electrodes.

[0064] The process of driving the flame (step S40) can be performed at various timings. For example, the flame may be driven after the lowering of the burner 50 (step S50) is completed. Alternatively, the burner tip 50s may be driven before the ignition of the burner 50 (step S30).

[0065] The material of the mold 20 is not limited to graphite. Various materials, such as boron nitride, can be used as long as they possess the required thermal shock resistance and thermal conductivity. Furthermore, the material of the oscillator is not limited to fused silica. Any dielectric material that undergoes melt deformation may be used.

[0066] Furthermore, the technical elements described herein or in the drawings demonstrate technical usefulness individually or in various combinations, and are not limited to the combinations described in the claims at the time of filing. In addition, the technologies illustrated herein or in the drawings can achieve multiple objectives simultaneously, and achieving even one of these objectives itself constitutes technical usefulness. [Explanation of Symbols]

[0067] 1: Melt molding apparatus 10: Plate 20: Mold 20h: Hole 20p: Support column 20s Top surface 30: Quartz plate 45: Electric stage 50: Burner 50s: Burner tip 53: Movable mechanism 70: Control unit 81: Negative pressure generating means 261~264: Electrode FL: Flame

Claims

1. A melt molding die comprising a flat upper surface and a hole formed in a part of the upper surface with a central axis perpendicular to the upper surface, A burner having a burner tip positioned above the central axis and facing the hole, and configured to generate a flame from the burner tip toward the hole, A flame position control unit controls the position of the flame so that it can move in a planar direction parallel to the upper surface, Equipped with, The flame position control unit comprises a plurality of electrode pairs arranged symmetrically with respect to the central axis around the flame. The flame position control unit is configured to be able to apply either a negative polarity voltage or a positive polarity voltage opposite to the negative polarity to each of the plurality of electrode pairs. In the electrode pair to which the negative polarity voltage is applied, the cross-sectional shape of the flame in the planar direction can be stretched in the direction toward the electrode pair. Melt molding apparatus.

2. A melt molding die comprising a flat upper surface and a hole formed in a part of the upper surface with a central axis perpendicular to the upper surface, A burner having a burner tip positioned above the central axis and facing the hole, and configured to generate a flame from the burner tip toward the hole, A flame position control unit controls the position of the flame so that it can move in a planar direction parallel to the upper surface, A temperature sensor for measuring the temperature of the melt molding die, the temperature sensor is configured to measure the temperature of three or more measurement points arranged around the hole in a rotationally symmetrical manner with respect to the central axis, Equipped with, The temperature sensor is configured to measure the temperature of the upper surface of the melt molding die in a non-contact manner. The flame position control unit is configured to control the position of the flame in the planar direction so as to reduce the temperature difference between the measured temperatures at three or more of the measurement points. Melt molding apparatus.

3. The melting molding apparatus according to claim 1 or 2, wherein the flame position control unit controls the position of the burner tip in the planar direction so as to be movable while maintaining a substantially constant distance between the burner tip and the upper surface.

4. The flame position control unit is equipped with three or more electrodes arranged around the flame in a rotationally symmetric manner with respect to the central axis. The melt molding apparatus according to claim 1 or 2, wherein the flame position control unit controls the position of the flame in the planar direction so as to be movable by an electric field generated between three or more electrodes.

5. The flame position control unit is configured to apply either a voltage of a first polarity or a voltage of a second polarity opposite to the first polarity to each of the three or more electrodes. The melt molding apparatus according to claim 4, wherein the flame position control unit controls the electrode to which the voltage of the first polarity is applied to change.

6. The melting molding apparatus according to claim 3, wherein the flame position control unit is configured to move the position of the flame in the planar direction along a rotationally symmetric trajectory about the central axis.

7. The melt molding apparatus according to claim 1, wherein the flame position control unit controls the electrode pair to which the negative polarity voltage is applied in a manner that can be changed.

8. A melt molding die comprising a flat upper surface and a hole formed in a part of the upper surface with a central axis perpendicular to the upper surface, A burner having a burner tip positioned above the central axis and facing the hole, and configured to generate a flame from the burner tip toward the hole, A flame position control unit controls the position of the flame so that it can move in a planar direction parallel to the upper surface, A method for manufacturing a vibrator using a melt molding apparatus equipped with the following: The flame position control unit comprises a plurality of electrode pairs arranged symmetrically with respect to the central axis around the flame. The arrangement step involves placing a plate-shaped workpiece on the upper surface so as to cover the hole, The process of generating a flame from the tip of the burner, A heating step in which, while generating negative pressure in the hole, the flame position control unit moves the position of the flame and heats the workpiece with the flame, Equipped with, In the heating step, the flame position control unit applies either a negative polarity voltage or a positive polarity voltage opposite to the negative polarity to each of the plurality of electrode pairs. In the electrode pair to which the negative polarity voltage is applied, the cross-sectional shape of the flame in the planar direction can be stretched in the direction toward the electrode pair. A method for manufacturing an oscillator.

9. A melt molding die comprising a flat upper surface and a hole formed in a part of the upper surface with a central axis perpendicular to the upper surface, A burner having a burner tip positioned above the central axis and facing the hole, and configured to generate a flame from the burner tip toward the hole, A flame position control unit controls the position of the flame so that it can move in a planar direction parallel to the upper surface, A temperature sensor for measuring the temperature of the melt molding die, the temperature sensor is configured to measure the temperature of three or more measurement points arranged around the hole in a rotationally symmetrical manner with respect to the central axis, A method for manufacturing a vibrator using a melt molding apparatus equipped with the following: The temperature sensor is configured to measure the temperature of the upper surface of the melt molding die in a non-contact manner. The arrangement step involves placing a plate-shaped workpiece on the upper surface so as to cover the hole, The process of generating a flame from the tip of the burner, A heating step in which, while generating negative pressure in the hole, the flame position control unit moves the position of the flame and heats the workpiece with the flame, Equipped with, In the heating step, the flame position control unit controls the position of the flame in the planar direction so that the temperature difference between the three or more measurement points is reduced. A method for manufacturing an oscillator.

10. The method for manufacturing an oscillator according to claim 8 or 9, wherein in the heating step, the flame position control unit moves the position of the burner tip in the planar direction while maintaining a substantially constant distance between the burner tip and the upper surface.

11. The flame position control unit is equipped with three or more electrodes arranged around the flame in a rotationally symmetric manner with respect to the central axis. The method for manufacturing an oscillator according to claim 8 or 9, wherein in the heating step, the flame position control unit moves the position of the flame in the planar direction by an electric field generated between three or more electrodes.

12. The flame position control unit is configured to apply either a voltage of a first polarity or a voltage of a second polarity opposite to the first polarity to each of the three or more electrodes. The method for manufacturing an oscillator according to claim 11, wherein in the heating step, the flame position control unit changes the electrode to which the voltage of the first polarity is applied.

13. The method for manufacturing an oscillator according to claim 8 or 9, wherein in the heating step, the flame position control unit moves the position of the flame in the planar direction along a rotationally symmetric trajectory about the central axis.

14. The method for manufacturing an oscillator according to claim 8, wherein in the heating step, the flame position control unit changes the electrode pair to which the negative polarity voltage is applied.

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