Molten mold and glass vibrator

Abstract

To provide the melt molding die for manufacturing an oscillator.SOLUTION: A melt molding die includes: a rear surface; a front surface parallel to the rear surface; a hole formed in the front surface and having an inner wall surface formed of a circumference around the central axis perpendicular to the front surface and a hole bottom surface; and a pillar extending upward from the hole bottom surface around the central axis. The pillar includes a pillar bottom surface connected to the hole bottom surface and a pillar upper surface positioned at an upper end. The diameter of the pillar bottom surface is larger than that of the pillar upper surface.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] This specification relates to a melt molding die and a glass oscillator.

Background Art

[0002] Patent Document 1 discloses a Bird-bath Resonator Gyroscope (BRG) using fused silica as an oscillator as a gyro sensor capable of achieving high precision. A specific manufacturing method will be described. Prepare a melt molding die having a hole formed in a part of the upper surface. The hole is formed in a part of the upper surface around a central axis perpendicular to the upper surface of the molding die. Inside the hole, a support column extending upward from the bottom surface of the hole around the central axis is arranged. A glass plate (e.g., a quartz plate) is arranged so as to close the hole, the hole is depressurized, and the upper surface of the glass plate is heated with a burner. When the heated glass plate exceeds the softening point, melt deformation is started by the differential pressure.

[0003] First, the central part of the glass plate contacts the upper surface of the support column. Since the heat of the central part of the glass plate is exhausted through the support column, the deformation of the glass plate on the upper surface of the support column stops. Due to the continued heating, the glass plate around the support column deforms downward so as to enter the inside of the hole. As the deformation progresses, the distance from the burner, which is the heat source, increases and the heat input amount decreases, and at the same time, the heat exhaust amount through the support column increases, so it becomes difficult to deform. Therefore, the glass plate in the deep part closer to the bottom surface of the hole becomes more difficult to deform. By transferring the support column shape of the die to the glass plate, a hollow glass column part can be formed. Also, a substantially hemispherical glass peripheral part centered on the glass column part can be formed by the hole.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] To increase the sensitivity of a gyro sensor, it is necessary to reduce the difference (Δf) between the excitation frequency and the detection frequency of the glass resonator. The technology described herein provides a melt molding die capable of manufacturing a glass resonator that can increase the sensitivity of a gyro sensor. [Means for solving the problem]

[0006] The melt molding die disclosed herein has a back surface. The melt molding die has a surface parallel to the back surface. The melt molding die has a hole formed on the surface. The hole has an inner wall surface formed around a central axis perpendicular to the surface and a bottom surface. The melt molding die has a support column extending upward from the bottom surface of the hole with respect to the central axis. The support column has a bottom surface which is connected to the bottom surface of the hole and an upper surface which is located at the upper end. The diameter of the bottom surface of the support column is greater than the diameter of the upper surface of the support column.

[0007] The inventors focused on the circularity of the connection portion formed between the glass column and the surrounding glass portion. The connection portion is the part that connects the glass column and the surrounding glass portion. The connection portion is also the part that is formed near the bottom surface of the support column during melt molding. Circularity is an indicator of how close the shape of the connection portion is to a circle centered on the central axis. The inventors discovered that the higher the circularity of the connection portion, the more Δf can be reduced. In conventional glass oscillator manufacturing methods, the shape of the connection portion was determined by the cessation of deformation of the glass plate due to the decrease in heat input and the increase in heat dissipation. Therefore, it was difficult to improve the circularity of the connection portion. In the melt molding die disclosed herein, the diameter of the bottom surface of the support column of the die is made larger than the diameter of the top surface of the support column. This makes it possible to stop the deformation of the glass plate by bringing the glass plate into contact with the support column or approaching the support column when the connection portion is formed near the bottom surface of the support column. By transferring the shape of the mold, the shape of the connection point can be determined, which improves the circularity of the connection point compared to when the shape is determined by chance. As a result, glass oscillators with extremely small Δf can be stably fabricated. [Brief explanation of the drawing]

[0008] [Figure 1] This is a schematic cross-sectional view of the melt molding apparatus 1 of Example 1. [Figure 2] This is a top view of the melt molding apparatus 1 of Example 1. [Figure 3] These are enlarged perspective and cross-sectional views of the vicinity of support column 20p. [Figure 4] This is a flowchart illustrating the manufacturing process of glass oscillators. [Figure 5] This is a perspective view of a quartz plate 30 on which a glass oscillator 30v has been formed. [Figure 6] This is a cross-sectional view along the line VI-VI in Figure 5. [Figure 7] This is a cross-sectional side view of a conventional melt molding apparatus 1001. [Figure 8] This is a cross-sectional side view of a conventional melt molding apparatus 1001. [Figure 9] This is a cross-sectional side view of a conventional melt molding apparatus 1001. [Figure 10] This is a cross-sectional side view of a conventional melt molding apparatus 1001. [Figure 11] This is a cross-sectional side view of the melt molding apparatus 1 of this embodiment. [Figure 12] This is a cross-sectional view of support post 120p. [Figure 13] This is a cross-sectional view of support column 220p. [Figure 14] This is a cross-sectional view of support column 320p. [Figure 15] This is a cross-sectional view of support column 420p. [Modes for carrying out the invention] [Examples]

[0009] (Configuration of the melt molding apparatus 1) Figure 1 shows a schematic cross-sectional view of the melt molding apparatus 1. Figure 2 shows a top view of the melt molding apparatus 1. Figure 1 corresponds to the cross-sectional view along line II in Figure 2. Note that in Figure 2, the burner 50, radiation thermometer 60, movable mechanism 53, and stage 45 are omitted from the description.

[0010] The stage 45 is configured to be movable in the x and y directions (horizontal direction). The stage 45 has a flat mounting surface 45s. The mold 20 is mounted on the mounting surface 45s via a heat sink 40 and a plate 10.

[0011] The heat sink 40 is positioned between the 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.

[0012] The plate 10 is disposed on the heat sink 40. The plate 10 is a stainless steel base for installing the mold 20. The plate 10 has a function of cooling the mold 20. A first communication hole 10c1 is formed in the surface 10s of the plate 10. The first communication hole 10c1 is disposed at a position corresponding to the through hole 20e and is connected to the through hole 20e. The first communication hole 10c1 is connected to the negative pressure generating means 81 via the first communication path 10p1. The negative pressure generating means 81 is a means capable of generating a negative pressure in the hole 20h. The negative pressure generating means 81 may be, for example, a vacuum pump.

[0013] The mold 20 is disposed on the surface 10s of the plate 10. The mold 20 is a mold for melting and deforming the quartz plate 30 to form a hemispherical glass oscillator. The material of the mold 20 is graphite. In this embodiment, the mold 20 has a disk shape with a central axis CA. The mold 20 includes a lower surface 20r, an upper surface 20s, a hole 20h, a support 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. The hole 20h is a space having an inner wall surface formed by a circumference centered on the central axis CA. In this embodiment, the hole 20h has a shape that is drilled in a cylindrical shape centered on the central axis CA. The hole 20h has a bottom surface 20b. A plurality of through holes 20e penetrating the lower surface 20r are formed in the bottom surface 20b. The through hole 20e communicates with the first communication hole 10c1.

[0014] At the center of the hole portion 20h, a support column 20p extending vertically upward from the bottom surface 20b is arranged. The structure of the support column 20p will be described with reference to FIG. 3. FIG. 3(A) is an enlarged perspective view of the vicinity of the support column 20p. FIG. 3(B) is a cross-sectional view taken along line B-B of FIG. 3(A) and is a cross-sectional view passing through the central axis CA. The support column 20p is a cylinder having the central axis CA as the central axis and has a rotationally symmetric shape around the central axis CA. The support column 20p includes a support column bottom surface BS and a support column upper surface TS. The support column bottom surface BS is connected to the bottom surface 20b of the hole portion 20h and is a plane perpendicular to the central axis CA. The support column upper surface TS is located at the upper end of the support column 20p and is a plane perpendicular to the central axis CA.

[0015] The diameter of the support column 20p increases in a curved shape (i.e., non-linearly increases) from the support column upper surface TS toward the support column bottom surface BS. Therefore, the diameter R1 of the support column bottom surface BS is larger than the diameter R2 of the support column upper surface. Also, the side surface SS of the support column 20p has a gentle curved shape in a cross-sectional view passing through the central axis CA.

[0016] The support column upper surface TS is at a position lower than the upper surface 20s of the mold 20. Thereby, a gap GA1 is formed between the lower surface of the quartz plate 30 and the support column upper surface TS (see FIG. 1). The gap GA1 can be an arbitrary value, for example, 100 to 500 μm. By forming the gap GA1, in step S100 described later, when cutting an unnecessary flat portion by CMP or the like, the support column 20p can be prevented from being removed.

[0017] A quartz plate 30 is arranged on the upper surface 20s of the mold 20 so as to cover the hole portion 20h (see FIGS. 1 and 2). The quartz plate 30 is a workpiece material for forming a glass oscillator. The quartz plate 30 is made of fused silica. The thickness of the quartz plate 30 is, for example, 100 μm. In this embodiment, the quartz plate 30 is square, but it may be circular or regular hexagonal.

[0018] 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.

[0019] 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). The movable mechanism 53 can move the burner tip 50s up and down along the central axis CA.

[0020] By focusing the infrared thermometer 60 on the support column 20p, the infrared thermometer 60 can measure the temperature of the support column 20p non-contact. The temperature of the support column 20p corresponds to the temperature of the quartz plate 30 being processed. Since it is very difficult to align the focus point of the infrared thermometer 60, which is the measurement point, with the transparent quartz plate 30, it is possible to indirectly measure the temperature of the quartz plate 30 by measuring the temperature of the support column 20p.

[0021] The control unit 70 is connected to the stage 45, the movable mechanism 53, the gas flow regulator 52, the radiation thermometer 60, 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.

[0022] (Manufacturing process of glass oscillators) The manufacturing process of the glass oscillator will be explained using the flow chart in Figure 4. 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.

[0023] 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.

[0024] In step S30, the control unit 70 starts measuring the temperature of the support column 20p using the radiation thermometer 60. In step S40, 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.

[0025] 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.

[0026] 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 S40, 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 60, and the descent timing and the distance between the burner tip 50s and the quartz plate 30 may be determined by temperature feedback control.

[0027] 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 (approximately 1600°C), it can be melted and deformed so that it enters the hole 20h. The specific details of the melting deformation will be described later.

[0028] If it is determined in step S60 that the melting 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 stage. For example, it may be detected when the temperature of the support column 20p has risen to a temperature indicating the end of the processing stage. Alternatively, for example, it may be detected when a predetermined amount of time has elapsed.

[0029] In step S70, the control unit 70 controls the movable mechanism 53 to raise the burner 50. In step S80, the control unit 70 stops the burning of the burner 50 by controlling the movable mechanism 53 and extinguishes the flame.

[0030] 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 glass resonator is completed by removing the unformed area (wing portion 30h) on the outer circumference of the quartz plate 30 using methods such as CMP or laser cutting.

[0031] (Construction of a glass oscillator) The structure of the quartz plate 30 formed by melt molding is explained in the flow chart of Figure 4. Figure 5 shows a perspective view of the quartz plate 30 with the glass resonator 30v formed on it. Figure 6 shows a cross-sectional view along the line VI-VI in Figure 5. Note that the perspective view in Figure 5 does not take into account the thickness of the formed portion of the glass resonator 30v.

[0032] The quartz plate 30 comprises a wing portion 30h and a glass oscillator 30v. The wing portion 30h maintains the original state of the quartz plate 30 and is a part that was not contributed to the melt molding process. The glass oscillator 30v is a part of the quartz plate 30 that was stretched by melt molding. The glass oscillator 30v is manufactured in the central part of the quartz plate 30.

[0033] The glass resonator 30v comprises a column section PP, a connecting section CP, and a peripheral section SP. In this specification, the region formed by contact with the column 20p of the mold 20 during melt molding is defined as the column section PP. That is, the region below the upper end PPu is the column section PP. The apex of the glass resonator 30v is defined as the outer periphery CPc. The outer periphery CPc has a circular shape centered on the resonator's central axis VA. The region from the upper end PPu to the outer periphery CPc is defined as the connecting section CP. The region outside the outer periphery CPc is defined as the peripheral section SP. In other words, the glass resonator 30v has a structure in which the column section PP and the peripheral section SP are connected by the connecting section CP. Furthermore, the column section PP, the connecting section CP, and the peripheral section SP are integrally formed from glass material.

[0034] The column section PP has a tubular shape with the transducer central axis VA. The column section PP is formed by transferring the shape of the support column 20p of the mold 20. Therefore, the diameter of the column section PP in a cross section perpendicular to the transducer central axis VA increases in a curved manner from the bottom surface PPb to the top end PPu. That is, the diameter of the column section PP is larger on the upper side than on the lower side. The inner wall PPi of the column section PP has a first roughness. The first roughness is a roughness determined according to the surface roughness of the support column 20p.

[0035] The connecting section CP extends upward from the upper end PPu of the column section PP. The connecting section CP has a cylindrical shape centered on the central axis CA. The diameter of the connecting section CP in the direction perpendicular to the oscillator central axis VA increases from the upper end PPu upwards. The thinnest part TH of the glass material is formed in the connecting section CP.

[0036] The inner wall CPi of the connecting portion CP has a surface roughness of second roughness, which is smaller than the first roughness. This is because the inner wall CPi of the connecting portion CP does not come into contact with the support column 20p, and therefore the surface roughness of the support column 20p is not transferred to it. Thus, by measuring the roughness of the inner wall along the oscillator central axis VA, it is possible to identify the upper end PPu and the column portion PP. Then, by determining whether the identified column portion PP has a shape in which the upper diameter is larger than the lower diameter, it is possible to determine whether or not it was formed using the mold 20 of this embodiment.

[0037] The peripheral SP extends downward from the outer circumference CPc of the connecting part CP. The peripheral SP has a hollow, approximately hemispherical shape centered on the oscillator's central axis VA. The diameter of the peripheral SP in the direction perpendicular to the oscillator's central axis VA increases as it goes downward from the outer circumference CPc. When viewed from the direction of the oscillator's central axis VA (+z direction), the upper end PPu of the column PP, the thinnest part TH, and the outer circumference CPc of the connecting part CP are arranged in a concentric circular pattern around the oscillator's central axis VA.

[0038] (assignment) To increase the sensitivity of the gyro sensor, it is necessary to reduce the difference (Δf) between the excitation vibration frequency and the detection vibration frequency of the glass oscillator 30v. The inventors focused on the circularity of the connection part CP formed between the column part PP and the surrounding part SP. Circularity is an indicator of how close the shape of the connection part CP is to a circle centered on the oscillator's central axis VA. The inventors found that the higher the circularity of the connection part CP, the more Δf can be reduced. More specifically, the connection part CP has a nearly circular thinnest part TH centered on the oscillator's central axis VA. The inventors found that the higher the circularity of this thinnest part TH with respect to the oscillator's central axis VA, the more Δf can be reduced.

[0039] However, with conventional glass oscillator manufacturing methods, it was difficult to improve the circularity of the connection part CP. The reason for this is explained below. Figures 7-10 show a cross-sectional side view of a conventional melt molding apparatus 1001. The conventional melt molding apparatus 1001 is equipped with a support column 1020p whose diameter is constant in the direction of the central axis CA. The other configurations are the same as those of the melt molding apparatus 1 in Figure 1. Figure 7 shows the initial state of the heating process (step S50). Figures 8 and 9 show the state of the quartz plate 30 during melt deformation in order. Figure 10 shows the state when melt deformation is completed (step S60). The cross-sectional views in Figures 7-10 are the same as the cross-sectional view in Figure 1. Note that Figures 7-10 are enlarged views of the vicinity of the support column 1020p, and details such as the burner 50 have been omitted.

[0040] In the initial stage of processing shown in Figure 7, the quartz plate 30 and the upper surface TS of the support column 1020p are separated (facing each other) via a gap GA1. Therefore, immediately after heating the quartz plate 30 with the burner 50, the temperature distribution is such that the center of the quartz plate 30 (near the central axis CA) is the hottest, and the temperature decreases towards the outer periphery.

[0041] When the center of the quartz plate 30 exceeds its softening point, melting deformation is initiated by the differential pressure of the negative pressure generating means 81. As shown in Figure 8, the central part of the quartz plate 30 comes into contact with the upper surface TS of the support column. The heat from the central part of the quartz plate 30 is dissipated through the support column 1020p, causing the temperature of the central part to drop rapidly and stopping the deformation of the central part.

[0042] As the heating continues, the ambient temperature of the central part of the quartz plate 30 is maintained above its softening point. As a result, as shown in Figure 9, the quartz plate 30 around the upper surface TS of the support column deforms downward so as to enter the hole 20h. Consequently, the contact area between the side surface of the support column 1020p and the quartz plate 30 increases and moves downward over time.

[0043] As deformation progresses, the distance from the heat source, the burner 50, increases, reducing the amount of heat input, while the amount of heat dissipated via the support column 1020p increases, making it more difficult to heat. In other words, the closer to the bottom surface 20b of the mold 20 (the deeper the part), the more difficult it is to deform. As a result, the deformation of the quartz plate 30 stops, and the glass oscillator 30v is completed (Figure 10).

[0044] As shown in Figure 10, in the completed glass oscillator 30v, the column PP is formed in the region from the bottom surface PPb of the column to the top end PPu. In addition, the connection part CP is formed in the region from the top end PPu to the outer circumference CPc (lowest point). The thinnest part TH is formed in the connection part CP. Furthermore, the gap between the quartz plate 30 and the side surface of the support column 1020p widens as you move from the top end PPu towards the outer circumference CPc (see region A1). As the gap widens, the shape is less restricted by the support column 1020p, and the degree of freedom in the shape of the connection part CP increases. In other words, the shape of the connection part CP is determined by the deformation stopping due to the balance between heat input and heat dissipation. For this reason, it was difficult to improve the roundness of the thinnest part TH formed in the connection part CP.

[0045] (effect) Figure 11 shows a cross-sectional side view of the melt molding apparatus 1 of this embodiment. The melt molding apparatus 1 of this embodiment is equipped with a support column 20p whose diameter increases in a curved manner from the upper surface TS of the support column to the lower surface BS of the support column. Figure 11 is a diagram showing the completed state of the glass vibrator 30v, similar to Figure 10. The processing process leading to the completed state in Figure 11 is the same as the processing process in Figures 7-9 described above, so the explanation is omitted.

[0046] In this embodiment, the diameter of the support column 20p of the mold 20 increases from the top surface TS of the support column towards the bottom surface BS of the support column. This makes it possible to reduce the gap between the quartz plate 30 and the side surface of the support column in the support column 20p of this embodiment (see area A2) compared to the conventional support column 1020p (see area A1). In the area close to the bottom surface 20b of the mold 20 (i.e., in the deep part of the hole 20h), deformation of the quartz plate 30 can be stopped by bringing the quartz plate 30 into contact with the side surface of the support column 20p or bringing it close to the side surface of the support column 20p. Since the shape of the connecting part CP can be determined by transferring the shape of the support column 20p, the degree of freedom of the shape of the connecting part CP can be limited compared to the conventional manufacturing method. Therefore, it is possible to improve the roundness of the connecting part CP and the roundness of the thinnest part TH formed in the connecting part CP.

[0047] The region from the upper end PPu to the thinnest part TH is a region with a high degree of freedom in the shape that is formed naturally. Therefore, the larger the distance D1 from the upper end PPu to the thinnest part TH, the more difficult it becomes to control the shape of the thinnest part TH. In the technology of this embodiment, the diameter of the support column 20p is increased toward the bottom surface BS of the support column. This makes it possible to make the distance D1 of the support column 20p in this embodiment (see Figure 11) smaller than the distance D1 of the conventional support column 1020p (see Figure 10). Thus, it becomes possible to increase the roundness of the thinnest part TH.

[0048] During the melting process, the support columns 20p of the mold 20 become the hottest because they retain the least heat. As a result, the mold 20 deteriorates quickly (i.e., the support columns 20p shrink or burn out), leading to a problem of reduced durability. In the technology of this embodiment, the diameter of the support columns 20p of the mold 20 is increased from the top surface TS to the bottom surface BS of the support columns, thereby increasing the amount of heat dissipated by the support columns 20p. Therefore, shrinkage or burnout of the support columns 20p can be suppressed, and the durability of the mold 20 can be increased. [Examples]

[0049] Example 2 describes various modifications of the shape of the support column of the mold 20. Parts common to the melt molding apparatus 1 of Example 1 are given the same reference numerals, and their explanation is omitted.

[0050] Figure 12 shows a cross-sectional view of the first modified example, the support column 120p. The support column 120p has a shape that is rotationally symmetrical about the central axis CA. The diameter of the support column 120p increases linearly from the top surface TS to the bottom surface BS. In other words, the rate of change in diameter is constant in the direction along the central axis CA. As a result, the side surface SS of the support column 120p has a linear shape.

[0051] Figure 13 shows a cross-sectional view of the second modified example, the support column 220p. The support column 220p has a shape that is rotationally symmetrical about the central axis CA. The support column 220p has an intermediate surface MS perpendicular to the central axis CA. The intermediate surface MS is located between the top surface TS and the bottom surface BS. The diameter of the support column 220p is constant from the top surface TS to the intermediate surface MS, and increases curvedly (nonlinearly) from the intermediate surface MS towards the bottom surface BS. As a result, the side surface SS of the support column 220p has a shape in which the diameter increases towards the bottom surface BS near the base.

[0052] Let's explain the effect. The smaller the diameter of the circular outer circumference CPc, which is the apex of the glass oscillator 30v (i.e., the smaller the column diameter), the higher the Q value of the gyro sensor can be. In the column 220p, by providing the intermediate column surface MS, the column diameter can be increased only in the region close to the column bottom surface BS where the connection part CP is formed (i.e., the region near the base). It is possible to obtain the effects of the technology described herein while keeping the column diameter as small as possible.

[0053] Figure 14 shows a cross-sectional view of the third modified example, column 320p. Column 320p has a rotationally symmetric shape around the central axis CA. The diameter of column 320p increases discontinuously from the intermediate surface MS towards the bottom surface BS. As a result, the side surface SS of column 320p has a stepped shape near the base (see region A3).

[0054] Figure 15 shows a perspective view of the fourth modified example, the support column 420p. In Figure 15, the same reference numerals are used for parts that are the same as in Example 1 (Figure 3(A)). The support column 420p has a shape that is rotationally symmetrical around the central axis CA. The cross-section of the support column 420p perpendicular to the central axis CA is polygonal. In the example in Figure 15, the cross-section is octagonal. The effects are explained below. By making the cross-section polygonal, multiple protrusions can be formed on the side surface of the support column 420p. When the quartz plate 30 comes into contact with the support column 420p during melt molding, line contact can be made at the protrusions. Since the contact area can be reduced compared to surface contact, it is possible to improve the workability when pulling out the melt-molded column PP from the support column 420p.

[0055] 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. Furthermore, the technical elements described in this specification or drawings exhibit 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 in this specification or drawings can achieve multiple objectives simultaneously, and achieving even one of these objectives itself constitutes technical usefulness.

[0056] (modified version) The shape of the support column of the mold 20 is not limited to a shape that is rotationally symmetrical about the central axis CA. For example, it may be an asymmetrical shape about the central axis CA.

[0057] The shape of the hole 20h is not limited to a cylinder and can be various. For example, it may have a vessel shape in which the diameter of the hole 20h decreases linearly or nonlinearly toward the bottom surface 20b. Alternatively, it may have a stepped inner wall in which the diameter of the hole 20h decreases discontinuously toward the bottom surface 20b.

[0058] 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.

[0059] The following are embodiments of this technology. [Aspect 1] The back side, The surface parallel to the aforementioned back surface, A hole formed on the aforementioned surface, comprising an inner wall surface formed around a central axis perpendicular to the aforementioned surface and a hole bottom surface, A support column extending upward from the bottom surface of the hole with respect to the aforementioned central axis, A melt molding die comprising, The support column comprises a support column bottom surface which is the surface connected to the bottom surface of the hole, and a support column top surface which is the surface located at the upper end. A melt-molding mold in which the diameter of the base of the support column is larger than the diameter of the top of the support column. [Aspect 2] The melt molding die according to embodiment 1, wherein the diameter of the support column increases linearly from the upper surface of the support column toward the bottom surface of the support column. [Aspect 3] The melt molding die according to embodiment 1, wherein the diameter of the support column increases in a curved manner from the upper surface of the support column toward the bottom surface of the support column. [Aspect 4] The melt molding die according to embodiment 1, wherein the diameter of the support column increases discontinuously in a stepped manner from the upper surface of the support column to the lower surface of the support column. [Aspect 5] The support column has an intermediate surface which is located between the upper surface and the bottom surface of the support column and is perpendicular to the central axis. A melt-molding mold according to any one of embodiments 1-4, wherein the diameter of the support column is constant from the upper surface to the middle surface of the support column, and increases from the middle surface to the bottom surface of the support column. [Aspect 6] The molten mold according to any one of embodiments 1 to 5, wherein the support column has a shape that is rotationally symmetrical about the central axis. [Aspect 7] The melt-molding mold according to any one of embodiments 1-6, wherein the cross-section of the support column perpendicular to the central axis is polygonal. [Aspect 8] A tubular column having a central axis, wherein the surface roughness of the inner wall is a first roughness, and A connecting portion that extends upward from the upper end of the column portion in the direction of the central axis, has a cylindrical shape centered on the central axis, and whose diameter in the direction perpendicular to the central axis increases as it goes upward from the upper end of the column portion, The connecting portion wherein the surface roughness of the inner wall is a second roughness which is smaller than the first roughness, The surrounding portion extends downward from the outer circumference of the connecting portion and has a hollow, substantially hemispherical shape centered on the central axis, with the diameter in the direction perpendicular to the central axis increasing as it goes downward from the outer circumference of the connecting portion, A glass resonator comprising, The column portion, the connecting portion, and the surrounding portion are integrally formed from glass material. In the cross-section perpendicular to the central axis, the diameter of the column portion is greater on the upper side than on the lower side in the direction of the central axis. Glass oscillator. [Aspect 9] The glass vibrator according to embodiment 8, wherein the thinnest portion of the glass material is formed at the connection portion. [Explanation of symbols]

[0060] 1: Melt molding equipment 20: Molding mold 20s: Top surface 20r: Bottom surface 20h: Hole 20b Bottom surface 20p: Strut CA: Central axis TS: Strut top surface BS: Strut bottom surface

Claims

1. The back side, The surface parallel to the aforementioned back surface, A hole formed on the aforementioned surface, comprising an inner wall surface formed around a central axis perpendicular to the aforementioned surface and a hole bottom surface, A support column extending upward from the bottom surface of the hole with respect to the aforementioned central axis, A melt molding die comprising, The support column comprises a support column bottom surface which is connected to the bottom surface of the hole, a support column top surface which is located at the upper end, and a support column intermediate surface which is located between the support column top surface and the support column bottom surface and is perpendicular to the central axis. The diameter of the base of the support column is larger than the diameter of the top of the support column. A melt-molding mold in which the diameter of the support column is constant from the top surface to the middle surface of the support column, and increases from the middle surface to the bottom surface of the support column.

2. The melt molding die according to claim 1, wherein the diameter of the support column increases in a curved manner from the intermediate surface of the support column toward the bottom surface of the support column.

3. The melt molding die according to claim 1, wherein the diameter of the support column increases discontinuously in a stepped manner from the intermediate surface of the support column toward the bottom surface of the support column.

4. The melt molding die according to claim 1, wherein the support column has a shape that is rotationally symmetrical with respect to the central axis.

5. The melt molding die according to claim 1, wherein the cross-section of the support column perpendicular to the central axis is polygonal.

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