Fastening structure and plasma generating device

Abstract

To more appropriately fasten a ceramic member to a base with a screwing member.SOLUTION: A fastening structure comprises: a base composed of one or more members, and formed with a screw hole; a screwing member including a shaft having a thread to be screwed into the screw hole and a head formed on the end part of the shaft; and a ceramic member made of ceramic, and formed with an insertion hole into which the shaft of the screwing member is inserted, where the cross-sectional area of a portion of the screwing member that is inserted into the insertion hole is smaller than the cross-sectional area of the thread of the screwing member.SELECTED DRAWING: Figure 7

Description

[Technical field]

[0001] The present disclosure relates to a fastening structure for fastening a ceramic member made of ceramic to a base with a screw member. [Background technology]

[0002] The following patent document describes a technique for fastening a ceramic member to a base with a screw member. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2012-004495 A Summary of the Invention [Problem to be solved by the invention]

[0004] An object of the present specification is to appropriately fasten a ceramic member to a base by a screw member. [Means for solving the problem]

[0005] In order to solve the above problems, the present specification provides a screw member that is composed of one or more members and has a base with a screw hole formed therein, a shaft with a thread formed thereon to screw into the screw hole, and a head formed on an end of the shaft, a ceramic member made of ceramic and having an insertion hole through which the shaft of the screw member is inserted, a plate-shaped member disposed between the base and the ceramic member, the plate-shaped member having a Young's modulus lower than that of one or more members of the base that are located on the ceramic member side and that of the ceramic member; Equipped with A recess is formed on at least one of the upper surface and the lower surface of the plate-like member. A fastening structure and the like are disclosed. Effect of the Invention

[0006] According to the present disclosure, the ceramic member can be properly fastened to the base. [Brief description of the drawings]

[0007] [Figure 1] FIG. 1 is a diagram showing a plasma device. [Diagram 2] FIG. 2 is a perspective view showing a plasma head. [Diagram 3] 1 is a cross-sectional view of the plasma head cut in the X direction and the Z direction at the positions of the electrodes and the plasma passage on the main body side. [Figure 4] FIG. 4 is a cross-sectional view taken along line AA in FIG. [Diagram 5] FIG. 3 is a cross-sectional view taken along line BB in FIG. [Figure 6] FIG. 1 is a perspective view showing a plasma head of the present invention. [Figure 7] 1 is a cross-sectional view showing a plasma head of the present invention. [Figure 8] FIG. 13 is a schematic view showing an intermediate member in a warped state. [Figure 9] FIG. 11 is a cross-sectional view showing a plasma head of a modified example. [Figure 10] FIG. 11 is a cross-sectional view showing a plasma head of a modified example. [Figure 11] FIG. 11 is a cross-sectional view showing a plasma head of a modified example. [Figure 12] FIG. 11 is a cross-sectional view showing a plasma head of a modified example. [Figure 13] FIG. 11 is a cross-sectional view showing a plasma head of a modified example. [Figure 14] FIG. 13 is a schematic view showing an intermediate member in a warped state. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings as modes for carrying out the present invention.

[0009] As shown in Fig. 1, the plasma device 10 includes a plasma head 11, a robot 13, and a control box 15. The plasma head 11 is attached to the robot 13. The robot 13 is, for example, a serial link type robot (which can also be called an articulated robot). The plasma head 11 is capable of irradiating plasma gas while being held at the tip of the robot 13. The plasma head 11 is capable of moving three-dimensionally in response to the drive of the robot 13.

[0010] The control box 15 is mainly composed of a computer, and performs overall control of the plasma device 10. The control box 15 has a power supply unit 15A that supplies power to the plasma head 11, and a gas supply unit 15B that supplies gas to the plasma head 11. The power supply unit 15A is connected to the plasma head 11 via a power cable (not shown). The power supply unit 15A changes the voltage applied to the electrode 33 (see Figures 3 and 4) of the plasma head 11 based on the control of the control box 15.

[0011] Moreover, the gas supply unit 15B is connected to the plasma head 11 via a plurality of gas tubes 19 (four in this embodiment). The gas supply unit 15B supplies reactive gas, carrier gas, and heat gas, which will be described later, to the plasma head 11 under the control of the control box 15. The control box 15 controls the gas supply unit 15B, and controls the amount of gas supplied from the gas supply unit 15B to the plasma head 11. As a result, the robot 13 operates under the control of the control box 15, and irradiates the workpiece W placed on the table 17 with plasma gas from the plasma head 11.

[0012] The control box 15 also includes an operation unit 15C having a touch panel and various switches. The control box 15 displays various setting screens and operation states (e.g., gas supply state, etc.) on the touch panel of the operation unit 15C. The control box 15 also receives various information by operation input to the operation unit 15C.

[0013] As shown in FIG. 2, the plasma head 11 includes a plasma generating unit 21, a heat gas supply unit 23, and the like. The plasma generating unit 21 generates plasma gas by converting the processing gas supplied from the gas supply unit 15B (see FIG. 1) of the control box 15 into plasma. The heat gas supply unit 23 generates heat gas by heating the gas supplied from the gas supply unit 15B. The plasma head 11 of this embodiment ejects the plasma gas generated in the plasma generating unit 21, together with the heat gas generated by the heat gas supply unit 23, onto the workpiece W shown in FIG. 1. The processing gas is supplied to the plasma head 11 from the upstream side to the downstream side in the direction of the arrow shown in FIG. 2. The plasma head 11 may be configured not to include the heat gas supply unit 23. That is, the plasma device of the present disclosure may be configured not to use heat gas.

[0014] As shown in Fig. 3 and Fig. 4, the plasma generating unit 21 includes a housing 31, a pair of electrodes 33, a plasma irradiation unit 35, and the like. Fig. 3 is a cross-sectional view cut in accordance with the positions of the pair of electrodes 33 and a plurality of main body side plasma passages 71 described later, and Fig. 4 is a cross-sectional view taken along line AA in Fig. 3. The housing 31 is composed of a base 36 made of a resin having high heat resistance, and a ceramic member 38 made of ceramic having high heat resistance. As shown in Fig. 5, the ceramic member 38 is fastened to the base 36 by four bolts 40 (only three are shown in the figure). Fig. 5 is a cross-sectional view taken along line BB in Fig. 2.

[0015] 5, the ceramic member 38 is generally cubic in shape, and a notch 41 extending in the vertical direction is formed on each of the four sides of the ceramic member 38 extending in the vertical direction. An insertion hole 43 is formed. The inner diameter of the insertion hole 43 is slightly larger than the outer diameter of the shaft 45 of the bolt 40 and smaller than the outer diameter of the head 46 of the bolt 40. The inner dimension of the notch 41 of the ceramic member 38 is larger than the outer diameter of the head of the bolt 40. The shaft 45 of the bolt 40 is formed with a screw thread 47.

[0016] The base 36 also has a generally cubic shape, and the outer dimensions of the lower surface of the base 36 are approximately the same as the upper surface of the ceramic member 38. Then, screw holes 48 having a shape corresponding to the threads 47 of the shaft 45 of the bolt 40 are formed in each of the four corners of the lower surface of the base 36. The four screw holes 48 are formed in the base 36 so as to vertically coincide with the four insertion holes 43 formed in the ceramic member 38.

[0017] The ceramic member 38 is disposed with the upper surface of the ceramic member 38 in close contact with the lower surface of the base 36, and the four screw holes 48 of the base 36 communicate with the four insertion holes 43 of the ceramic member 38. The tip of the shaft 45 of the bolt 40 is inserted from the lower end of the insertion hole 43 of the ceramic member 38, and is inserted through the insertion hole 43 to the screw hole 48, so that the thread 47 formed on the shaft 45 is screwed into the screw hole 48. At this time, the ceramic member 38 is sandwiched between the head 46 of the bolt 40 and the screw hole 48 into which the thread 47 of the bolt 40 is screwed, so that the base 36 and the ceramic member 38 are integrated. In this way, the ceramic member 38 is bolted to the base 36 by the four bolts 40, so that the base 36 and the ceramic member 38 are integrated as the housing 31.

[0018] In this way, in the housing 31 in which the base 36 and the ceramic member 38 are integrated, a reaction chamber 51 for generating plasma gas is formed inside the ceramic member 38, as shown in FIG. 3. Each of the pair of electrodes 33 is, for example, cylindrical, and is fixed with its tip protruding into the reaction chamber 51. In the following description, the pair of electrodes 33 may be simply referred to as the electrodes 33. The direction in which the pair of electrodes 33 are arranged is referred to as the X direction, the direction in which the plasma generating unit 21 and the heat gas supply unit 23 are arranged is referred to as the Y direction, and the axial direction of the cylindrical electrode 33 is referred to as the Z direction. In this embodiment, the X direction, the Y direction, and the Z direction are perpendicular to each other.

[0019] As shown in Fig. 2 and Fig. 4, the heat gas supply unit 23 includes a gas pipe 52, a heater 53, a connection unit 54, etc. The gas pipe 52 and the heater 53 are attached to the outer circumferential surface of the housing 31, and are covered by a cover 55 shown in Fig. 4. The gas pipe 52 is connected to the gas supply unit 15B of the control box 15 via a gas tube (see Fig. 1) 19. Gas (e.g., air) is supplied to the gas pipe 52 from the gas supply unit 15B. The heater 53 is attached midway through the gas pipe 52. The heater 53 heats the gas flowing through the gas pipe 52 to generate heat gas.

[0020] 4, the connecting part 54 connects the gas pipe 52 to the plasma irradiation part 35. When the plasma irradiation part 35 is attached to the housing 31, one end of the connecting part 54 is connected to the gas pipe 52, and the other end is connected to a heat gas passage 56 formed in the plasma irradiation part 35. Heat gas is supplied to the heat gas passage 56 via the gas pipe 52.

[0021] 3, a part of the outer periphery of the electrode 33 is covered by an electrode cover 57 made of an insulator such as ceramics. The electrode cover 57 is substantially hollow and cylindrical, with openings formed at both ends in the longitudinal direction. A gap between the inner periphery of the electrode cover 57 and the outer periphery of the electrode 33 functions as a gas passage 58. The downstream opening of the electrode cover 57 is connected to the reaction chamber 51. The lower end of the electrode 33 protrudes from the downstream opening of the electrode cover 57.

[0022] In addition, a reaction gas flow passage 61 and a pair of carrier gas flow passages 63 are formed inside the base 36 of the housing 31. The reaction gas flow passage 61 is connected to the gas supply unit 15B via a gas tube 19 (see FIG. 1), and causes the reaction gas supplied from the gas supply unit 15B to flow into the reaction chamber 51. The pair of carrier gas flow passages 63 are disposed at positions sandwiching the reaction gas flow passage 61 in the X direction. Each of the pair of carrier gas flow passages 63 is connected to the gas supply unit 15B via a gas tube 19 (see FIG. 1), and a carrier gas is supplied from the gas supply unit 15B. The carrier gas flow passage 63 causes the carrier gas to flow into the reaction chamber 51 via the gas passage 58.

[0023] As the reactive gas (seed gas), oxygen (O2) can be used. The gas supply unit 15B, for example, flows a mixed gas of oxygen and nitrogen (N2) (e.g., dry air (Air)) between the electrodes 33 of the reaction chamber 51 via the reactive gas flow passage 61. Hereinafter, for convenience, this mixed gas may be referred to as the reactive gas, and oxygen may be referred to as the seed gas. As the carrier gas, nitrogen can be used. The gas supply unit 15B flows the carrier gas from each of the gas passages 58 so as to surround each of the pair of electrodes 33.

[0024] An AC voltage is applied to the pair of electrodes 33 from the power supply unit 15A of the control box 15. By applying the voltage, for example, as shown in Fig. 3, a pseudo arc A is generated between the lower ends of the pair of electrodes 33 in the reaction chamber 51. When the reactive gas passes through this pseudo arc A, the reactive gas is turned into plasma. Therefore, the pair of electrodes 33 generates a discharge of the pseudo arc A, turns the reactive gas into plasma, and generates plasma gas.

[0025] An internal nozzle 65 is fitted inside the reaction chamber 51 in the housing 31, and is located below the lower ends of the pair of electrodes 33 inside the reaction chamber 51. The internal nozzle 65 has a plurality of (six in this embodiment) internal nozzle plasma passages 67 arranged at intervals in the X direction and extending in the Z direction. The upstream ends of the multiple internal nozzle plasma passages 67 open into the upper end surface of the internal nozzle 65 and are connected to the reaction chamber 51. On the other hand, the downstream ends of the multiple internal nozzle plasma passages 67 open into the lower end surface of the internal nozzle 65.

[0026] A plurality of (six in this embodiment) main body side plasma passages 71 are formed at the lower end of the housing 31 that is in close contact with the lower end surface of the internal nozzle 65, and are aligned at intervals in the X direction and extend in the Z direction. The upstream ends of the plurality of main body side plasma passages 71 communicate with the lower ends of the plurality of internal nozzle plasma passages 67.

[0027] The plasma irradiation unit 35 includes a nozzle 73, a nozzle cover 75, and the like. The nozzle 73 is generally T-shaped in side view from the X direction, and is composed of a nozzle body 77 and a nozzle tip 79. The nozzle 73 is an integral body of the nozzle body 77 and the nozzle tip 79, and is made of ceramics having high heat resistance. The nozzle body 77 is generally flange-shaped and is fixed to the lower surface of the housing 31 by a bolt 80. The nozzle tip 79 is shaped to extend downward from the lower surface of the nozzle body 77. The nozzle 73 is formed with a plurality of (six in this embodiment) nozzle-side plasma passages 81 that penetrate the nozzle body 77 and the nozzle tip 79 in the vertical direction, that is, in the Z direction, and the plurality of nozzle-side plasma passages 81 are arranged at intervals in the X direction. The plurality of nozzle-side plasma passages 81 are formed at the same positions as the plurality of body-side plasma passages 71 in the Z direction. Therefore, the body-side plasma passage 71 and the nozzle-side plasma passage 81 communicate with each other.

[0028] The nozzle cover 75 is generally T-shaped when viewed from the side in the X direction, and is composed of a cover body 85 and a cover tip 87. 5 and the cover tip 87, and is made of ceramics with high heat resistance. The cover body 85 is generally plate-shaped with a plate thickness, and a recess 89 is formed in the cover body 85, which opens on the upper surface and is recessed in the Z direction. The cover body 85 is fixed to the lower surface of the ceramic member 38 of the housing 31 by a bolt 90 so that the nozzle body 77 of the nozzle 73 is stored in the recess 89. Therefore, the nozzle cover 75 is detachable from the housing 31, and is removed from the housing 31 when replacing the nozzle 73, etc. Furthermore, the cover body 85 is formed with a heat gas passage 56 extending in the Y direction, with one end of the heat gas passage 56 opening in the recess 89 and the other end of the heat gas passage 56 opening on the side surface of the cover body 85. The end of the heat gas passage 56 opening on the side surface of the cover body 85 is connected to the connection portion 54 of the heat gas supply unit 23 described above.

[0029] The cover tip 87 extends downward from the lower surface of the cover body 85. A through hole 93 penetrating in the Z direction is formed in the cover tip 87, and the upper end of the through hole 93 communicates with the recess 89 of the cover body 85. The nozzle tip 79 of the nozzle 73 is inserted into the through hole 93. As a result, the nozzle 73 is entirely covered by the nozzle cover 75. The lower end of the nozzle tip 79 of the nozzle 73 and the lower end of the cover tip 87 of the nozzle cover 75 are located at the same height.

[0030] Furthermore, with the nozzle 73 covered by the nozzle cover 75, the nozzle body 77 of the nozzle 73 is positioned inside the recess 89 of the nozzle cover 75, and the nozzle tip 79 of the nozzle 73 is positioned inside the through hole 93 of the nozzle cover 75. In this state, there are gaps between the recess 89 and the nozzle body 77, and between the through hole 93 and the nozzle tip 79, and these gaps function as a heat gas output passage 95. Heat gas is supplied to the heat gas output passage 95 via the heat gas passage 56.

[0031] With this structure, the plasma gas generated in the reaction chamber 51 passes through the main body side plasma passage 71 and the nozzle side plasma passage 81 together with the carrier gas, and is ejected from the opening 81A at the lower end of the nozzle side plasma passage 81. The heat gas supplied to the heat gas passage 56 from the gas pipe 52 flows through the heat gas output passage 95. This heat gas functions as a shield gas that protects the plasma gas. The heat gas flows through the heat gas output passage 95 and is ejected from the opening 95A at the lower end of the heat gas output passage 95 along the ejection direction of the plasma gas. At this time, the heat gas is ejected so as to surround the periphery of the plasma gas ejected from the opening 81A of the nozzle side plasma passage 81. In this way, the efficacy (wettability, etc.) of the plasma gas can be improved by ejecting the heated heat gas around the plasma gas.

[0032] In this way, in the plasma head 11, a discharge occurs in the reaction chamber 51, and a plasma is generated, and the plasma gas is ejected from the tip of the nozzle 73, and the workpiece W is subjected to plasma processing. At this time, since the reaction chamber 51 becomes hot, the ceramic member 38 of the housing 31 in which the reaction chamber 51 is formed is made of ceramic with high heat resistance. However, although ceramic is a material with high heat resistance, it is a material with a low Young's modulus. The Young's modulus is a proportional constant between the amount of strain and the stress in the elastic range, and is the ratio of the stress to the amount of strain. Therefore, when an object with a high Young's modulus and an object with a low Young's modulus are deformed with the same stress, the object with the low Young's modulus deforms more than the object with the high Young's modulus. In other words, an object with a low Young's modulus is easily deformed, and an object with a high Young's modulus is difficult to deform. Therefore, the ceramic member 38 made of ceramic with a low Young's modulus is easily deformed. On the other hand, the base 36 in the housing 31 that is in close contact with the upper surface of the ceramic member 38 is made of resin with high heat resistance, but its heat resistance is lower than that of the ceramic member 38. In addition, the resin that is the material of the base 36 has a lower Young's modulus than ceramic. The base 36 is more easily deformed than the ceramic member 38. The bolt 40 that fastens the ceramic member 38 with its head 46 in close contact with the underside of the ceramic member 38 is made of steel, and the Young's modulus of steel is higher than that of resin and ceramic. In other words, the Young's modulus of the bolt 40 that fastens the ceramic member 38 is higher than that of the ceramic member 38, and the bolt 40 is less likely to deform than the ceramic member 38.

[0033] That is, the upper surface of the ceramic member 38 is in close contact with the base 36, which has a lower Young's modulus than the ceramic member 38, and the lower surface of the ceramic member 38 is in close contact with the head 46 of the bolt 40, which has a higher Young's modulus than the ceramic member 38. As the plasma head 11 is repeatedly used, the temperature of the housing 31 repeatedly changes between high temperature and room temperature. During this process, the ceramic member 38 undergoes repeated thermal expansion and contraction, and the ceramic member 38, which is easily deformed, is significantly deformed when thermal expansion and contraction are repeated. In other words, thermal stress is repeatedly generated in the ceramic member 38, causing the ceramic member 38 to deform significantly.

[0034] Furthermore, the tightening torque of the bolt 40 is generated in the ceramic member 38 which is in close contact with the head 46 of the bolt 40. As described above, there is a risk that the ceramic member 38 which is in close contact with the head 46 of the bolt 40 will be damaged due to the deformation of the ceramic member 38 when thermal stress occurs, the tightening torque of the bolt 40, and the like. In particular, since the ceramic member 38 is fastened by the bolt at the notch portion 41, stress is concentrated at the boundary between the contact surface of the ceramic member 38 with the head 46 of the bolt 40 and the side surface of the notch portion 41 which intersects with the contact surface, and there is a high possibility that the ceramic member 38 will be damaged at the boundary.

[0035] Furthermore, when the temperature of the housing 31 repeatedly changes between high temperature and room temperature, the base 36 also repeatedly undergoes thermal expansion and contraction, but since the Young's modulus of the base 36 is lower than that of the ceramic member 38, the easily deformed base 36 undergoes large deformation in association with the thermal expansion of the base 36. For this reason, even if the ceramic member 38 is urged toward the head 46 of the bolt 40 due to the deformation of the base 36, there is a risk that the ceramic member 38 in close contact with the head 46 of the bolt 40 will be damaged.

[0036] In consideration of this, in the plasma head 11, as shown in Figures 6 and 7, the ceramic member 38 is fastened to the base 36 by a bolt 100 whose diameter at the center of the shaft is smaller than the diameter at the tip end. A washer 106 is disposed between a head 102 of the bolt 100 and the ceramic member 38, and two plate-shaped intermediate members 110, 112 are disposed in a stacked state between the base 36 and the ceramic member 38.

[0037] Specifically, a thread 118 is formed at the tip of the shaft 116 of the bolt 100, and a portion 122 between a portion 120 where the thread 118 is formed (hereinafter referred to as the "tip portion") of the bolt 100 and the head 102 (hereinafter referred to as the "center portion") is thinner than the tip portion 120. In other words, the radial cross-sectional area of ​​the center portion 122 of the shaft 116 of the bolt 100 is smaller than the cross-sectional area of ​​the tip portion 120. The washer 106 has an annular shape, and the inner diameter of the washer 106 is larger than the outer diameter of the center portion 122 of the shaft 116 of the bolt 100, and the outer diameter of the washer 106 is approximately the same as or larger than the outer diameter of the head 102 of the bolt 100. The washer 106 is disposed between each of the heads 102 of the four bolts 100 and the ceramic member 38.

[0038] The two plate-like intermediate members 110, 112 are plate-shaped and have approximately the same dimensions as the upper surface of the ceramic member 38. The two plate-like intermediate members 110, 112 are stacked, with the thickness of the upper intermediate member (hereinafter referred to as the "first intermediate member") 110 being approximately half the thickness of the lower intermediate member (hereinafter referred to as the "second intermediate member") 112. The first intermediate member 110 is flat, but has a thickness on the upper surface of the second intermediate member 112. A recess 126 is formed in the upper surface of the second intermediate member 112. The recess 126 is a cross-shaped groove that passes through the center of the upper surface of the second intermediate member 112, and ends of the recess 126 are open to the four side surfaces of the second intermediate member 112. The depth dimension of the recess 126 is approximately the same as the thickness dimension of the first intermediate member 110. The first intermediate member 110 and the second intermediate member 112 are layered with the upper surface of the second intermediate member 112, in which the recess 126 is formed, in close contact with the lower surface of the first intermediate member 110.

[0039] The first intermediate member 110 and the second intermediate member 112 in a stacked state are disposed between the upper surface of the ceramic member 38 and the lower surface of the base 36. The first intermediate member 110 and the second intermediate member 112 are formed with insertion holes 128, 130 having the same inner dimensions as the insertion hole 43 formed in the ceramic member 38. The shaft 116 of the bolt 100 is inserted into the insertion holes 43, 128, 130 of the ceramic member 38, the first intermediate member 110, and the second intermediate member 112, and the thread 118 is screwed into the screw hole 48 of the base 36, thereby integrally fastening the base 36, the ceramic member 38, the first intermediate member 110, and the second intermediate member 112. The central portion 122 of the shaft 116 of the bolt 100 passes through the insertion holes 43, 128, 130 of the ceramic member 38, the first intermediate member 110 and the second intermediate member 112, and the tip portion 120 of the shaft 116 is screwed into the screw hole 48 of the base 36.

[0040] The washer 106, the first intermediate member 110, and the second intermediate member 112 are molded from a resin material or a rubber material having high heat resistance. The washer 106, the first intermediate member 110, and the second intermediate member 112 may be molded from the same material or different materials. Examples of the resin material or the rubber material having high heat resistance include PEEK, PPS, PES, fluorine-based rubber, and silicon-based rubber. The Young's modulus of the washer 106 is lower than that of the bolt 100, that is, the head 102, and the ceramic member 38, and the Young's modulus of the first intermediate member 110 and the second intermediate member 112 is lower than that of the base 36 and the ceramic member 38.

[0041] In this way, the washer 106, which has a Young's modulus lower than that of the head 102 and the ceramic member 38 of the bolt 100, is disposed between the head 102 and the ceramic member 38, thereby preventing damage due to deformation of the ceramic member 38. In more detail, when the ceramic member 38 thermally expands, if the washer 106 is not disposed between the ceramic member 38 and the head 102, the ceramic member 38, which has a Young's modulus lower than that of the head 102, is deformed. On the other hand, if the washer 106 is disposed between the ceramic member 38 and the head 102, the head 102 of the bolt 100 and the washer 106, which has a Young's modulus lower than that of the ceramic member 38, are deformed when the ceramic member 38 thermally expands. Furthermore, if the washer 106 is not disposed between the ceramic member 38 and the head 102, the tightening torque of the bolt 100 is generated in the ceramic member 38, but if the washer 106 is disposed between the ceramic member 38 and the head 102, the tightening torque is generated in the washer 106. The washer 106, which has a lower Young's modulus than the head 102 and the ceramic member 38, is deformed by the tightening torque of the bolt 100. In other words, when thermal stress occurs, the washer 106 is deformed instead of the ceramic member 38, and the washer 106 is deformed instead of the ceramic member 38 by the tightening torque of the bolt 100, etc. This makes it possible to suppress deformation of the ceramic member 38 and prevent damage to the ceramic member 38.

[0042] Furthermore, by disposing the first intermediate member 110 and the second intermediate member 112, which have a lower Young's modulus than the base 36 and the ceramic member 38, between the base 36 and the ceramic member 38, it is possible to prevent damage due to deformation of the ceramic member 38. In more detail, if the first intermediate member 110 and the second intermediate member 112 were not disposed between the base 36 and the ceramic member 38 when the base 36 thermally expands, the base 36 would deform and the ceramic member 38 would be urged toward the head 102 of the bolt 100. On the other hand, if the first intermediate member 110 and the second intermediate member 112 were not disposed between the base 36 and the ceramic member 38, the base 36 would deform and the ceramic member 38 would be urged toward the head 102 of the bolt 100. In the case where the first intermediate member 110 and the second intermediate member 112 are disposed between the base 36 and the ceramic member 38, when the base 36 thermally expands, the first intermediate member 110 and the second intermediate member 112, which have a lower Young's modulus than the base 36 and the ceramic member 38, are deformed. In other words, when thermal stress occurs, the first intermediate member 110 and the second intermediate member 112 are deformed instead of the ceramic member 38. This makes it possible to suppress the urging of the ceramic member 38 against the head 102 of the bolt 100 and prevent damage to the ceramic member 38.

[0043] In addition, by disposing two members, the first intermediate member 110 and the second intermediate member 112, between the base 36 and the ceramic member 38, the load applied to the ceramic member 38 can be reduced, and damage to the ceramic member 38 can be prevented. In detail, for example, when a plate-shaped intermediate member 140 shown in FIG. 8 is disposed between the base 36 and the ceramic member 38, the intermediate member 140 warps with its center protruding downward. This is because the reaction chamber 51 is formed inside the ceramic member 38, so that the ceramic member 38 becomes hot, and the lower surface of the intermediate member 140 in contact with the ceramic member 38 expands significantly, while the upper surface of the intermediate member in contact with the base 36, which is cooler than the ceramic member 38, does not expand as much as the lower surface. Then, a force for returning the warp of the intermediate member 140 is applied to the ceramic member 38. The force F for returning the warp of the intermediate member 140 is calculated by the following formula. F = {(48 × E × I) / L3} × σ Here, E is the Young's modulus of the intermediate part 140, I is the second moment of area, and L is the length dimension of the intermediate part 140. Also, σ is the amount of warping of the intermediate part 140, as shown in Fig. 8. The second moment of area I is proportional to the cube of the thickness dimension of the intermediate part 140. Here, the thickness dimension of the intermediate part 140 is 3t.

[0044] Furthermore, in order to prevent damage to the ceramic member 38 between the base 36 and the ceramic member 38 in the same manner as the intermediate member 140, the thickness dimension of the two members, the first intermediate member 110 and the second intermediate member 112, is 3t. As described above, the thickness dimension of the first intermediate member 110 is approximately half the thickness dimension of the second intermediate member 112. Therefore, the thickness dimension of the first intermediate member 110 is t, and the thickness dimension of the second intermediate member 112 is 2t. The depth dimension of the recess 126 formed in the second intermediate member 112 is t because it is the same as the thickness dimension of the first intermediate member 110.

[0045] When the two members, the first intermediate member 110 and the second intermediate member 112, are disposed between the base 36 and the ceramic member 38, the second intermediate member 112, which is in contact with the ceramic member 38, warps with its center portion protruding downward, similar to the intermediate member 140. At this time, a force F for returning the warp of the second intermediate member 112 is generated in a portion below the recess 126 of the second intermediate member 112. For this reason, the second moment of area I used in calculating the force F for returning the warp of the second intermediate member 112 is proportional to the cube of the thickness dimension of the portion below the recess 126 of the second intermediate member 112. In other words, since the thickness dimension of the second intermediate member 112 is 2t and the depth dimension of the recess 126 is t, the thickness dimension of the portion of the second intermediate member 112 below the recess 126 is t (=2t-t), and the second moment of area I used when calculating the force F to restore the warp of the second intermediate member 112 is proportional to the cube of t.

[0046] In this way, when the two members, the first intermediate member 110 and the second intermediate member 112, are disposed between the base 36 and the ceramic member 38, the second moment of area I is proportional to the cube of t (t3). On the other hand, when the intermediate member 140 is disposed between the base 36 and the ceramic member 38, the second moment of area I is proportional to the cube of 3t (27t3). For this reason, the force F for restoring the warp of the second intermediate member 112 is 1 / 27 of the force F for restoring the warp of the intermediate member 140. In other words, when the two members, the first intermediate member 110 and the second intermediate member 112, are disposed between the base 36 and the ceramic member 38, the load applied to the ceramic member 38 is proportional to the cube of t (t3). The load applied to the ceramic member 38 when the ceramic member 38 is supported by the first intermediate member 110 and the second intermediate member 112 is 1 / 27 of the load applied to the ceramic member 38 when the ceramic member 38 is supported by the first intermediate member 110 and the second intermediate member 112. By disposing the two members, the first intermediate member 110 and the second intermediate member 112, between the base 36 and the ceramic member 38 in this manner, the load applied to the ceramic member 38 can be reduced and damage to the ceramic member 38 can be prevented.

[0047] 7, by fastening ceramic member 38 to base 36 with bolt 100 in which the diameter of central portion 122 of shaft 116 is smaller than the diameter of tip portion 120, it is possible to reduce the load applied to ceramic member 38 and prevent damage to ceramic member 38. More specifically, the spring constant K of bolt 100 is calculated by the following formula. K = A × (E / L) Here, A is the cross-sectional area of ​​the portion of the bolt 100 receiving the load, and L is the length dimension of the portion of the bolt 100 receiving the load. Also, E is the Young's modulus of the bolt 100. Therefore, the smaller the cross-sectional area A of the portion of the bolt 100 receiving the load, the smaller the spring constant K of the bolt 100. Also, the smaller the spring constant, the easier it is to stretch. In other words, the smaller the cross-sectional area of ​​the bolt 100, the easier it is to stretch. The bolt 100 is fastened to the base 36 at the tip portion 120 with a large cross-sectional area, and is inserted through the insertion hole 43 of the ceramic member 38 at the central portion 122 with a small cross-sectional area. Therefore, when the ceramic member 38 or the like expands, the bolt 100 stretches at the central portion 122, thereby reducing the load applied to the ceramic member 38. This makes it possible to prevent damage to the ceramic member 38.

[0048] Incidentally, the plasma head 11 is an example of a plasma generating device. The housing 31 is an example of a fastening structure. The electrode 33 is an example of an electrode. The base 36 is an example of a base and one or more members. The ceramic member 38 is an example of a ceramic member. The insertion hole 43 is an example of an insertion hole. The screw hole 48 is an example of a screw hole. The reaction chamber 51 is an example of a reaction chamber. The reaction gas flow path 61 is an example of a gas flow path. The nozzle 73 is an example of a nozzle. The bolt 100 is an example of a screw member. The head 102 is an example of a head. The first intermediate member 110 is an example of a plate-like member, and the second intermediate member 112 is an example of a plate-like member. The shaft 116 is an example of a shaft. The thread 118 is an example of a thread. The recess 126 is an example of a recess.

[0049] As described above, the present embodiment has the following advantages.

[0050] In the plasma head 11, the ceramic member 38 is fastened to the base 36 by the bolt 100, whose central portion 122 of the shaft 116 has a smaller cross-sectional area than the tip portion 120. The bolt 100 is fastened to the base 36 at the tip portion 120, which has a larger cross-sectional area, and passes through the insertion hole 43 of the ceramic member 38 at the central portion 122, which has a smaller cross-sectional area. Since the central portion 122 of the shaft 116 is thin, the spring constant of the central portion 122 is small and it is easy to stretch, as described above. Therefore, when the ceramic member 38 or the like expands, the bolt 100 stretches at the central portion 122, thereby reducing the load applied to the ceramic member 38 and preventing damage to the ceramic member 38.

[0051] In addition, in the plasma head 11, the second intermediate member 112, which has a lower Young's modulus than the base 36 and the ceramic member 38, is disposed between the base 36 and the ceramic member 38, and a recess 126 is formed in the second intermediate member 112. Therefore, the thickness dimension of the portion of the second intermediate member 112 where the recess 126 is formed is reduced, and as described above, the force F for returning the warp of the second intermediate member 112 to its original shape is reduced. This reduces the load applied to the ceramic member 38, and prevents damage to the ceramic member 38.

[0052] In addition, in the plasma head 11, not only the second intermediate member 112 but also the first intermediate member 110 is disposed between the base 36 and the ceramic member 38. The first intermediate member 110 and the second intermediate member 112 are laminated together. Therefore, by ensuring the thickness with the two plate-like members, the first intermediate member 110 and the second intermediate member 112, it is possible to increase the amount of deformation of the first intermediate member 110 and the second intermediate member 112. This reduces the load applied to the ceramic member 38, and prevents damage to the ceramic member 38.

[0053] In the plasma head 11, a recess 126 is formed on the upper surface of the second intermediate member 112, and the first intermediate member 110 is laminated on the upper surface of the second intermediate member 112. In other words, the recess 126 is formed on the contact surface between the first intermediate member 110 and the second intermediate member 112, and a gap is formed between the first intermediate member 110 and the second intermediate member 112. This makes it possible to mitigate the expansion of the first intermediate member 110 and the second intermediate member 112 between the first intermediate member 110 and the second intermediate member 112.

[0054] The plasma head 11 is a device that generates plasma by generating discharge in the reaction chamber 51. In the plasma head 11, the first intermediate member 110 and the second intermediate member 112 are disposed between the base 36 and the ceramic member 38, thereby preventing damage to the ceramic member 38. This makes it possible to appropriately suppress damage to the ceramic member 38 that is caused by temperature changes in the housing 31 when the plasma head 11 is used repeatedly. In particular, since the reaction chamber 51 is formed inside the ceramic member 38, it is possible to appropriately protect the ceramic member 38, which is susceptible to temperature changes.

[0055] More specifically, a pair of electrodes 33 that discharge when a voltage is applied are disposed in the ceramic member 38, and a reactive gas flow path 61 for supplying a reactive gas to the reaction chamber 51 is formed. Also, a nozzle 73 for ejecting plasma generated in the reaction chamber 51 is attached to the lower surface side of the ceramic member 38. Therefore, by protecting the ceramic member 38, it is possible to also protect the electrodes 33, the reactive gas flow path 61, the nozzle 73, etc.

[0056] The present disclosure is not limited to the above embodiment, and can be embodied in various forms with various modifications and improvements based on the knowledge of a person skilled in the art. Specifically, for example, in the above embodiment, the first intermediate member 110 is laminated on the upper surface of the second intermediate member 112, and the recess 126 is formed on the upper surface of the second intermediate member 112. On the other hand, as shown in FIG. 9, the second intermediate member 112 may be laminated on the upper surface of the first intermediate member 110, and the recess 126 may be formed on the lower surface of the second intermediate member 112. Also, as shown in FIG. 10, the second intermediate member 112 may be laminated on the upper surface of the first intermediate member 110, and the recess 126 may be formed on the upper surface of the second intermediate member 112. Also, as shown in FIG. 11, the first intermediate member 110 may be laminated on the upper surface of the second intermediate member 112, and the recess 126 may be formed on the lower surface of the second intermediate member 112. In addition, when the first intermediate member 110 is laminated on the upper surface of the second intermediate member 112 and the recess 126 is formed on the lower surface of the second intermediate member 112, the lower surface of the second intermediate member 112 on which the recess 126 is formed comes into contact with the ceramic member 38. Therefore, when the second intermediate member 112 warps with its central portion protruding downward, the central portion of the lower surface of the second intermediate member 112 hardly comes into contact with the upper surface of the ceramic member 38 because the recess 126 is formed in the central portion of the lower surface of the second intermediate member 112. As a result, almost no load is applied to the ceramic member 38 due to the warping of the second intermediate member 112, and damage to the ceramic member 38 can be appropriately prevented.

[0057] In the above embodiment, two plate-like members, the first intermediate member 110 and the second intermediate member 112, are disposed between the base 36 and the ceramic member 38, but three or more plate-like members may be disposed between the base 36 and the ceramic member 38. On the other hand, as shown in Fig. 12, one intermediate member 150 may be disposed between the base 36 and the ceramic member 38. Then, a recess 126 is formed in the center of the lower surface of the intermediate member 150, so that the intermediate member 150 warps and the ceramic member is almost entirely removed, similar to the second intermediate member 112 shown in Fig. 11. Since no load is applied to the ceramic member 38, damage to the ceramic member 38 can be appropriately prevented.

[0058] In the above embodiment, the recess 126 is formed in the center of the second intermediate member 112, but as shown in FIG. 13, the recess 162 may be formed in the outer edge of the first intermediate member 160. That is, the recess 162 may be formed by cutting out the edges of the four sides of a plate-like member, and the plate-like member may be laminated on the upper surface of the second intermediate member 112. In this way, by cutting out the edges of the four sides of the plate-like member to form the recess 162, the amount of warping can be reduced. Specifically, for example, as shown in FIG. 14, the amount of warping of the intermediate member 170 in which no recess is formed is t1. On the other hand, when the recess 182 is formed in the outer edge of the upper surface of the intermediate member 180, the amount of warping of the intermediate member 180 is t2, which is less than the amount of warping of the intermediate member 170 in which no recess is formed. This reduces the load on the ceramic member 38 due to the warping of the intermediate member 180, and prevents damage to the ceramic member 38.

[0059] In the above embodiment, the first intermediate member 110 and the second intermediate member 112 are disposed between the base 36 and the ceramic member 38, and the ceramic member 38 is fastened by the bolt 100 at the central portion 122 which is thinner than the tip portion 120. On the other hand, the first intermediate member 110 and the second intermediate member 112 are disposed between the base 36 and the ceramic member 38, but the ceramic member 38 may be fastened by a general bolt, that is, a bolt having an axis with the same diameter. Also, the ceramic member 38 may be fastened by the bolt 100 at the central portion 122 which is thinner than the tip portion 120, without disposing the first intermediate member 110 and the second intermediate member 112 between the base 36 and the ceramic member 38.

[0060] In the above embodiment, the bolts 100, the first intermediate member 110, and the second intermediate member 112 are used when the ceramic member 38 is bolted, but the bolts 100, the first intermediate member 110, and the second intermediate member 112 may be used when a ceramic nozzle 73 or the like is bolted. Furthermore, the fastening structure using the bolts 100, the first intermediate member 110, and the second intermediate member 112 can be adopted not only in the plasma head 11 but also in various devices, mechanisms, systems, etc. that fasten ceramic members with bolts as a base.

[0061] In addition, in the above embodiment, a structure is adopted in which the ceramic members are fastened by the bolt 100, but various structures can be adopted as long as the fastening structure is one in which the threads are screwed into the screw hole. [Explanation of symbols]

[0062] 11: plasma head (plasma generating device), 31: housing (fastening structure), 33: electrode, 36: base (one or more members), 38: ceramic member, 43: insertion hole, 48: screw hole, 51: reaction chamber, 61: reaction gas flow path (gas flow path), 73: nozzle, 100: bolt (screwed member), 102: head, 110: first intermediate member (plate-shaped member), 112: second intermediate member (plate-shaped member), 116: shaft, 118: screw thread, 126: recess

Claims

1. A base including one or more members and having a screw hole formed therein; a threaded member having a shaft with a screw thread that screws into the screw hole and a head formed on an end of the shaft; a ceramic member having an insertion hole through which the shaft of the screw member is inserted; a plate-shaped member disposed between the base and the ceramic member, the plate-shaped member having a Young's modulus lower than a Young's modulus of a member located on the ceramic member side among one or more members of the base and a Young's modulus of the ceramic member; Equipped with A fastening structure in which a recess is formed on at least one of the upper and lower surfaces of the plate-like member.

2. a plurality of the plate-like members are arranged in a stacked state between the base and the ceramic member, The fastening structure according to claim 1 , wherein a recess is formed in at least one of the plurality of plate-like members.

3. The fastening structure according to claim 2 , wherein recesses are formed on surfaces of the plurality of plate-like members that are in contact with one another when stacked.

4. 4. The fastening structure according to claim 1, wherein a cross-sectional area of ​​the portion of the screw member that is inserted into the insertion hole is smaller than a cross-sectional area of ​​a portion of the screw member where the thread is formed.

5. A base including one or more members and having a screw hole formed therein; a threaded member having a shaft with a screw thread that screws into the screw hole and a head formed on an end of the shaft; a ceramic member having an insertion hole through which the shaft of the screw member is inserted; a reaction chamber formed within the ceramic member; a pair of electrodes disposed inside the ceramic member for generating plasma from a processing gas in the reaction chamber by application of a voltage; a gas flow passage formed within the ceramic member for supplying a process gas to the reaction chamber; a nozzle attached to the ceramic member for discharging a gas that has been converted into plasma in the reaction chamber; a plate-shaped member disposed between the base and the ceramic member, the plate-shaped member having a Young's modulus lower than a Young's modulus of a member located on the ceramic member side among one or more members of the base and a Young's modulus of the ceramic member; Equipped with A plasma generating device in which a recess is formed on at least one of the upper and lower surfaces of the plate-like member.

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