JP7726682B2 - Molding device and molding method - Google Patents

Description

This specification relates to a vibrator molding device and molding method.

Patent Document 1 discloses a Bird-bath Resonator Gyroscope (BRG) that uses fused silica as an oscillator, making it possible to achieve high accuracy. Specifically, a quartz plate is placed in a mold with a hole formed in its surface so that it covers the hole. While reducing the pressure inside the hole, the top surface of the quartz plate is heated with a burner. By melting and deforming the quartz plate so that it fills the hole, a hemispherical oscillator can be created.

US Patent Application Publication No. 2018/079129

When using burner heating, the flame fluctuates, resulting in variations in temperature distribution and between lots. This makes it difficult to reproducibly and stably manufacture oscillators of the same shape.

One embodiment of a molding device disclosed herein includes a heating coil capable of high-frequency induction heating a conductor. The molding device includes a chamber. The molding device includes a non-conductive base disposed within the chamber. The molding device includes a first conductor portion disposed on the base. The first conductor portion includes a cavity on its upper surface that has an axially rotationally symmetric shape with respect to a central axis. The molding device includes a conductive support portion disposed inside the cavity and having a cylindrical shape centered on the central axis. The molding device includes a pressure reduction mechanism capable of reducing the pressure in the cavity.

The first conductor and support can be heated by high-frequency induction heating using a heating coil. Compared to heating using a burner, this method eliminates the effects of flame fluctuations, making it possible to suppress variations in temperature distribution and between lots. This makes it possible to improve processing accuracy and reproducibility.

The axially symmetric shape of the cavity may be cylindrical.

It may further include a second conductor portion disposed opposite the cavity and movable along the central axis. Details of the effects will be explained in the examples.

The second conductor portion may have at least one of a first exhaust hole located at a position corresponding to the central axis of the region facing the cavity, and a plurality of second exhaust holes located at rotationally symmetric positions equidistant from the central axis of the region facing the cavity. The first exhaust hole and the plurality of second exhaust holes may be configured to be able to eject heated inert gas. Details of the effects will be explained in the examples.

A protrusion having an axially rotationally symmetric shape with respect to the central axis may be formed in the region of the second conductor facing the cavity. The outer diameter of the protrusion may be smaller than the inner diameter of the opening of the cavity. Details of the effect will be explained in the examples.

It may also be equipped with a measuring mechanism that can monitor the reduced pressure state within the cavity. Details of the effects will be explained in the examples.

A plurality of first conductors may be provided. The distance between the first conductor and the heating coil may be equal for each of the plurality of first conductors. Details of the effects will be explained in the examples.

The first conductor portion may contain graphite.

One embodiment of the molding method disclosed herein is a molding method using a molding apparatus. The molding apparatus includes a heating coil capable of high-frequency induction heating a conductor. The molding apparatus includes a chamber. The molding apparatus includes a non-conductive base disposed within the chamber. The molding apparatus includes a first conductor portion disposed on the base, the first conductor portion having a cavity on its upper surface that has an axially rotationally symmetric shape about a central axis. The molding apparatus includes a conductive support portion disposed inside the cavity and having a cylindrical shape centered on the central axis. The molding apparatus includes a decompression mechanism capable of decompressing the cavity. The molding method includes a placement step of placing a plate-shaped workpiece material on the upper surface of the first conductor portion so as to cover the cavity. The molding method includes a processing step of heating the first conductor portion and the support portion with a heating coil to melt and deform the workpiece material while decompressing the interior of the cavity with the decompression mechanism. Details of the effects will be explained in the examples.

The molding method may further include a monitoring step of monitoring the reduced pressure state of the cavity during the processing step. The end point of the processing step may be detected based on the results of monitoring the reduced pressure state. Details of the effects will be explained in the examples.

The molding device may further include a second conductor portion disposed opposite the cavity and movable along the central axis. During the processing step, the second conductor portion heated by the heating coil may be brought into contact with the workpiece material. Details of the effects will be explained in the examples.

The second conductor portion may have at least one of a first exhaust hole located at a position corresponding to the central axis of the region facing the cavity, and a plurality of second exhaust holes located at rotationally symmetric positions equidistant from the central axis of the region facing the cavity. During the processing step, heated inert gas may be ejected from the first exhaust hole and the plurality of second exhaust holes. Details of the effects will be explained in the examples.

1 is a cross-sectional view of a molding device 1 of Example 1. FIG. FIG. 2 is a top view of the cross section taken along line II-II in FIG. FIG. 10 is a cross-sectional view after melt deformation. 10 is a graph showing monitored pressure. FIG. 10 is a cross-sectional view of a molding apparatus 201 according to a second embodiment. FIG. 10 is a cross-sectional view of a molding apparatus 301 according to a third embodiment. FIG. 10 is a cross-sectional view of a molding apparatus 401 according to a fourth embodiment. FIG. 8 is a top view of the cross section taken along line VIII-VIII in FIG. 7. FIG. 10 is a diagram showing a modified molding device 501.

Figures 1 and 2 show the molding apparatus 1 of Example 1. Figure 1 is a cross-sectional view. Figure 2 is a top view of the cross section taken along line II-II in Figure 1. Note that the chamber 10 and heating coil 11 are omitted from Figure 2. The molding apparatus 1 includes the chamber 10, heating coil 11, susceptor 13, pressure reduction mechanism 14, measurement mechanism 15, base mold 20, first conductor 21, support 23, and quartz plate 30.

The chamber 10 is a sealed container that houses the susceptor 13 and base mold 20. Heated inert gas (e.g., nitrogen or argon) is supplied through the intake holes 10i of the chamber 10. The heating coil 11 is a component used to high-frequency induction heat the first conductor portion 21 and support pillar 23, which are conductors. The heating coil 11 is arranged around the chamber 10.

The susceptor 13 is a circular platform on which the base mold 20 is placed. The shape of the susceptor 13 is not limited to the circular shape shown in FIG. 2 . For example, it may be square. The material of the susceptor 13 may be high-heat-resistant ceramics. Examples of materials include alumina, zirconia, SiC, Si ₃ N ₄ , and BN. From the viewpoint of material cost, alumina is preferable. The susceptor 13 has an exhaust pipe 13 e in the center of the bottom surface 13 b. The exhaust pipe 13 e is connected to a pressure reduction mechanism 14 and a measurement mechanism 15. The pressure reduction mechanism 14 is a mechanism capable of vacuuming, such as a vacuum pump. The measurement mechanism 15 is a mechanism capable of monitoring the reduced pressure state, such as a pressure gauge.

The base mold 20 is placed on the susceptor 13 and has a disk shape. A material having high insulating properties and high heat resistance can be used for the base mold 20. Examples of the material include BN (boron nitride), alumina, zirconia, SiC, _{and Si3N4} . BN is preferred because of its ease of processing.

A hole 20a is formed in the surface 20s of the base mold 20, shaped like a hollow cylinder centered on the central axis CA1. A first conductor 21 and a support 23 are disposed inside the hole 20a. The first conductor 21 and the support 23 can be made of a conductive material with a high melting point. Examples of such materials include isotropic graphite and high-melting-point metals such as Ta, Nb, and Mo. Isotropic graphite is preferred due to its ease of processing.

The first conductor 21 is a cylindrical member having a cylindrical shape centered on the central axis CA1. The inner surface of the hole 20a and the outer surface of the first conductor 21 may be fitted together without any gap, or a certain gap may be formed. A cavity 21c is formed inside the first conductor 21, which is a deformation space for the quartz plate 30 to melt and deform. In other words, the first conductor 21 has a cavity 21c on its upper surface that has an axially rotationally symmetric shape (cylindrical shape) with respect to the central axis CA1.

The support pillar 23 has a cylindrical shape centered on the central axis CA1. An engagement groove 20t is formed in the bottom surface 20b of the hole 20a. The lower surface of the support pillar 23 engages with the engagement groove 20t. In FIG. 1, the z-direction position of the upper surface of the support pillar 23 is lower than the z-direction position of the surface 20s. Therefore, the upper surface of the support pillar 23 does not contact the lower surface of the quartz plate 30. As a variant, the z-direction positions of the upper surface of the support pillar 23 and the surface 20s may be the same, and the upper surface of the support pillar 23 may contact the lower surface of the quartz plate 30.

The inner peripheral portion 20r1 of the back surface of the base mold 20 is recessed relative to the outer peripheral portion 20r2 of the back surface. A space 20o is formed between the inner peripheral portion 20r1 of the back surface and the bottom surface 13b of the susceptor 13. The space 20o is connected to the pressure reduction mechanism 14 via an exhaust pipe 13e.

The bottom surface 20b of the base mold 20 is provided with an exhaust port 20e and intake holes 20v1 and 20v2 that penetrate the inner periphery 20r1 of the back surface. The exhaust port 20e connects the cavity 21c to the space 20o. With the top of the cavity 21c blocked by the quartz plate 30, the cavity 21c can be placed in a reduced pressure state by evacuating the space 20o. The upper end of the intake hole 20v1 is in contact with the back surface of the first conductor 21. The upper end of the intake hole 20v2 is in contact with the back surface of the support 23. As a result, by evacuating the space 20o, the first conductor 21 and the support 23 can be adsorbed and fixed to the base mold 20.

A quartz plate 30 is placed on the surface 20s so as to cover the hole 20h. The quartz plate 30 is the material to be processed to form the vibrator. 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 rectangular or circular.

(manufacturing process)
The vibrator manufacturing process will be described with reference to Figures 1 and 3. In step S1, a base mold 20 is placed on a susceptor 13. In step S2, a quartz plate 30 is placed on the surface 20s of the base mold 20 so as to cover the cavity 21c. In step S3, an inert gas preheated to 1000°C or higher is supplied through the intake port 10i of the chamber 10. By replacing the atmosphere in the chamber with the inert gas, oxidation of the graphite components (first conductor 21, support 23) can be prevented. In addition, the cavity 21c is depressurized by the depressurization mechanism 14. The quartz plate 30 is fixed by adsorption to the surface 20s. This results in the state shown in Figure 1.

In step S4, a monitoring process is initiated in which the measurement mechanism 15 monitors the reduced pressure state of the cavity 21c. This allows the degree of vacuum in the cavity 21c to be controlled to a constant level.

In step S5, the processing process begins. Specifically, the first conductor 21 and the support 23 are heated by high-frequency induction using the heating coil 11. Because the heat-generating conductor is present only in the portion that forms the cavity 21c, it is possible to selectively heat only the quartz plate 30 near the cavity 21c.

In step S6, the end point of the processing process is detected based on the results of monitoring the reduced pressure state. Specifically, as shown in Figure 3, the quartz plate 30 suddenly melts and deforms, causing a sudden decrease in the volume of the space formed by the cavity 21c and the quartz plate 30. This causes a spike-like pressure fluctuation in the pressure monitored by the measurement mechanism 15, as shown in Figure 4. The start time t0 of this pressure fluctuation is taken as the starting point, and time t1, after a certain time pt has elapsed, can be determined as the processing end point. Because the amount of heat applied to the quartz plate 30 can be kept constant, it is possible to suppress lot-to-lot variation in the processed shape.

In step S7, the high-frequency induction heating and preheating of the introduced inert gas are terminated upon detecting the end point of processing. After the quartz plate 30 has cooled to the desired temperature, the cavity 21c is opened to the atmosphere. The melt-processed quartz plate 30 is removed from the chamber 10. Note that steps S6 and S7 may be omitted. In this case, heating may be terminated upon the passage of a predetermined time from the start of heating. In step S8, the unformed region UR (see Figure 3) of the quartz plate 30 is removed by a method such as CMP, thereby completing the vibrator.

(effect)
When a quartz plate is heated with a burner as in conventional technology, flame fluctuations result in variations in temperature distribution and temperature variations between lots. It is difficult to create a vibrator with a uniform hemispherical shape or to reproducibly and stably manufacture vibrators of the same shape. The technology described herein allows the first conductor 21 and the support 23 to be heated by high-frequency induction heating using a heating coil 11. Compared to heating using a burner, the effect of flame fluctuations can be eliminated, making it possible to suppress variations in temperature distribution and temperature variations between lots. This makes it possible to improve the precision and reproducibility of vibrator processing.

Figure 5 shows a cross-sectional view of the molding apparatus 201 of Example 2. Example 2 differs from Example 1 in that it further includes a second conductor portion 22. Components common to the molding apparatus 1 of Example 1 are given the same reference numerals and will not be described again. Note that the chamber 10 and susceptor 13 are not shown in Figure 5.

The second conductor portion 22 is a cylindrical member. The second conductor portion 22 is disposed opposite the cavity 21c and is movable up and down along the central axis CA1. As with the first conductor portion 21, the second conductor portion 22 can be made of a conductive, high-melting-point material. In this embodiment, the material of the second conductor portion 22 is isotropic graphite. It is preferable that the diameter D1 of the second conductor portion 22 is larger than the inner diameter D2 of the opening of the cavity 21c. It is also preferable that the relationship "D2≦D1≦1.5×D2" is satisfied.

A dome-shaped protrusion 22p is formed in the region of the second conductor 22 facing the cavity 21c, with the central axis CA1 as its apex. That is, the protrusion 22p has an axially rotationally symmetric shape with respect to the central axis CA1. The outer diameter D3 of the protrusion 22p is equal to or less than the inner diameter D2 of the cavity 21c. It is preferable that the relationship "0.8 × D2 ≦ D3 ≦ D2" be satisfied. The height H1 of the protrusion 22p from the lower surface 22r of the second conductor 22 is set to H1. The distance R1 is set to the surface 21s of the first conductor 21 to the upper surface 23t of the support 23. The height H1 is equal to or less than the distance R1. It is also preferable that the relationship "0.8 × R1 ≦ H1 ≦ R1" be satisfied. This size relationship allows the protrusion 22p to enter the cavity 21c. That is, the protrusion 22p and the cavity 21c can engage with each other.

A first exhaust hole 22e1 is disposed at a position corresponding to the central axis CA1 of the region of the second conductor 22 facing the cavity. The first exhaust hole 22e1 is a hole capable of ejecting heated inert gas. Furthermore, it is preferable that the diameter of the first exhaust hole 22e1 be smaller than the diameter D4 of the support 23.

Note that the distance R1 may be zero. In this case, the protrusion 22p may not be provided, and the height H1 may be zero. (In other words, the area of the second conductor 22 facing the cavity 21c may be flat.)

(manufacturing process)
Only the differences from the manufacturing process of Example 1 will be described. In the processing step of step S5, the second conductor 22 is high-frequency induction heated by the heating coil 11. The heated second conductor 22 is then moved downward along the central axis CA1. This brings the protrusion 22p into contact with the quartz plate 30. In addition, an inert gas heated to 1000°C or higher is ejected from the first exhaust hole 22e1.

(effect)
In addition to heating the quartz plate 30 from the bottom surface by the first conductors 21 and the supports 23, the quartz plate 30 can be heated from the top surface by the second conductors 22. This increases the heating efficiency, thereby shortening the processing time.

The quartz plate 30 can be heated by thermal conduction caused by contact with the second conductor 22. Because thermal conductivity can be increased compared to thermal conduction via inert gas, variations in temperature distribution can be suppressed. This makes it possible to improve processing accuracy and processing reproducibility.

As shown in Figure 3, even after the quartz plate 30 has melted and deformed and separated from the protrusion 22p, the quartz plate 30 can be heated by the inert gas ejected from the first exhaust hole 22e1. This allows for efficient finishing of the quartz plate 30.

Figure 6 shows a cross-sectional view of the molding device 301 of Example 3. In Example 3, the shape of the protrusion of the second conductor portion 22 differs from that of Example 2. Parts that are common to Example 2 are given the same reference numerals, and descriptions thereof will be omitted.

A protrusion 322p is formed in the region of the second conductor 22 facing the cavity 21c, protruding in a doughnut shape with the central axis CA1 as its apex. That is, the protrusion 322p has a concentric, rotationally symmetric shape about the central axis CA1. The outer diameter D5 of the protrusion 322p is equal to or smaller than the inner diameter D2 of the cavity 21c. It is preferable to satisfy the relationship "0.8 × D2 ≦ D5 ≦ D2". It is also preferable that the inner diameter D6 of the protrusion 322p is larger than the diameter D4 of the support 23. This size relationship allows the protrusion 322p to enter the cavity 21c.

(effect)
3, after melting and deforming, the quartz plate 30 has the greatest amount of deformation in the region between the upper surface 23t of the support 23 and the surface 21s of the first conductor 21. The protrusions 322p have concentric protrusions corresponding to the region where the deformation is greatest. As a result, by bringing the protrusions 322p into contact, the melting and deformation of the quartz plate 30 can be carried out more efficiently.

Figures 7 and 8 show the molding device 401 of Example 4. Figure 7 is a cross-sectional view. Figure 8 is a top view of the cross section taken along line VIII-VIII in Figure 7. Note that the quartz plate 430 is not shown in Figure 8. Example 4 has a structure that includes multiple first conductor portions 21 and second conductor portions 22 of Example 2. Parts that are common to the molding device 201 of Example 2 are given the same reference numerals, and descriptions thereof will be omitted.

The chamber 10 has a cylindrical shape centered on the central axis CA2. The heating coil 11 is arranged concentrically around the chamber 10, centered on the central axis CA2. The susceptor 13 and base mold 420 are disk-shaped, with their centers coinciding with the central axis CA2. The base mold 420 includes a plurality of first conductors 21. The central axes CA1 of the plurality of first conductors 21 are located on a circle CC centered on the central axis CA2. That is, the plurality of first conductors 21 are arranged equidistant from the central axis CA2. Therefore, the distance CD between the first conductors 21 and the heating coil 11 is equal for each of the plurality of first conductors 21. This reduces temperature variation among the plurality of first conductors 21. Shape variation among the vibrators can be suppressed, thereby improving yield.

Also, a jig 24 and multiple second conductors 22 are arranged inside the chamber 10. The jig 24 is a component for holding the multiple second conductors 22. The jig 24 is disk-shaped, and its center coincides with the central axis CA2. The jig 24 is movable up and down along the central axis CA2. The jig 24 can be made of a material with high insulating properties and high heat resistance. In this embodiment, the jig 24 is made of alumina. A plurality of second conductors 22 are fixed to the underside of the jig 24 in correspondence with the multiple first conductors 21. The structures of the first conductors 21 and second conductors 22 are the same as in Example 2, so a description thereof will be omitted. A circular quartz plate 430 is arranged on the surface 420s of the base mold 420 so as to cover the multiple cavities 21c.

(effect)
It is possible to simultaneously manufacture multiple vibrators in a single processing step, greatly improving vibrator production efficiency.

Specific examples of the present invention have been described in detail above, but these are merely examples and do not limit the scope of the claims. The technology described in the claims includes various modifications and variations of the specific examples given above.

(Modification)
In the fourth embodiment, the plurality of second conductors 22 may not be provided.

In Example 4, the position and number of exhaust holes provided in the second conductor portion 22 may vary. For example, as shown in a modified molding apparatus 501 in Figure 9, multiple second exhaust holes 22e2 may be provided. Figure 9(A) is a view of the underside of the second conductor portion 22 from the -z direction. Figure 9(B) is a cross-sectional view of the molding apparatus 501. In the region of the second conductor portion 22 facing the cavity 21c, four second exhaust holes 22e2 are arranged at rotationally symmetric positions equidistant from the central axis CA1. The heated inert gas ejected from the four second exhaust holes 22e2 enables more efficient heating of the quartz plate 30. Note that the number of second exhaust holes 22e2 is not limited to four and can be any number. Furthermore, the shape of the region where the second exhaust holes 22e2 are formed is not limited to the shape of the protrusion 22p in Figure 9 and may vary. For example, the second exhaust hole 22e2 may be formed in the protrusion 322p shown in the molding device 301 (Figure 6). Alternatively, the device may be configured to include both the first exhaust hole 22e1 (Figures 5 and 6) and the second exhaust hole 22e2 (Figure 9).

The support pillars 23 are not limited to being conductive and may be made of non-conductive material.

The material of the vibrator is not limited to the quartz plate 30. Any dielectric material that melts and deforms can be used.

Furthermore, the technical elements described in this specification or drawings may exhibit technical utility either alone or in various combinations, and are not limited to the combinations described in the claims at the time of filing. Furthermore, the technologies illustrated in this specification or drawings may achieve multiple objectives simultaneously, and achieving any one of those objectives is itself technically useful.

1, 201, 301, 401: Molding device 10: Chamber 11: Heating coil 14: Pressure reduction mechanism 15: Measuring mechanism 20: Base mold 21: First conductor 21c: Cavity 22: Second conductor 22e: Exhaust hole 22p: Protrusion 23: Support

Claims (9)

a heating coil capable of high-frequency induction heating a conductor;
a chamber;
a non-conductive base disposed within the chamber;
a first conductor disposed on the base, the first conductor having a cavity on its upper surface that has an axial rotation symmetric shape with respect to a central axis;
a conductive support portion that is disposed inside the cavity and has a cylindrical shape centered on the central axis;
a pressure reducing mechanism capable of reducing the pressure in the cavity;
a second conductor portion disposed opposite the cavity and movable along the central axis;
A molding device comprising: the second conductor portion includes at least one of a first exhaust hole arranged at a position corresponding to the central axis of the region facing the cavity, and a plurality of second exhaust holes arranged at rotationally symmetric positions equidistant from the central axis of the region facing the cavity,
The molding apparatus according to claim 1 , wherein the first exhaust hole and the plurality of second exhaust holes are configured to be able to eject heated inert gas. a protrusion having an axial rotation symmetric shape with respect to the central axis is formed in a region of the second conductor facing the cavity,
The molding apparatus according to claim 1 or 2 , wherein an outer diameter of the protrusion is smaller than an inner diameter of the opening of the cavity. The molding apparatus according to any one of claims 1 to 3 , further comprising a measuring mechanism capable of monitoring a reduced pressure state within the cavity. a plurality of the first conductor portions are provided,
The molding device according to claim 1 , wherein the distance between the first conductor and the heating coil is equal for each of the plurality of first conductors. The molding device according to claim 1 , wherein the first conductor portion includes graphite. a heating coil capable of high-frequency induction heating a conductor;
a chamber;
a non-conductive base disposed within the chamber;
a first conductor disposed on the base, the first conductor having a cavity on its upper surface that has an axial rotation symmetric shape with respect to a central axis;
a conductive support portion that is disposed inside the cavity and has a cylindrical shape centered on the central axis;
a pressure reducing mechanism capable of reducing the pressure in the cavity;
a second conductor portion disposed opposite the cavity and movable along the central axis;
A molding method using a molding apparatus comprising:
a placement step of placing a plate-shaped workpiece on the upper surface of the first conductor portion so as to cover the cavity;
a processing step of heating the first conductor portion and the support portion with the heating coil while reducing the pressure inside the cavity with the pressure reducing mechanism to melt and deform the workpiece material;
Equipped with
In the processing step, the second conductor portion heated by the heating coil is brought into contact with the workpiece.
Molding method. a monitoring step of monitoring a reduced pressure state of the cavity during the processing step,
The molding method according to claim 7 , further comprising detecting an end point of the processing step based on a result of monitoring the reduced pressure state. the second conductor portion includes at least one of a first exhaust hole arranged at a position corresponding to the central axis of the region facing the cavity, and a plurality of second exhaust holes arranged at rotationally symmetric positions equidistant from the central axis of the region facing the cavity,
The molding method according to claim 7 , wherein in the processing step, heated inert gas is ejected from the first exhaust hole and the plurality of second exhaust holes.