JP6871902B2 - Seal structure and its manufacturing method - Google Patents

Description

The present invention relates to a sealing structure including a sealing member that is interposed between the members and seals between the members, and a method for manufacturing the same.

For example, the vacuum casting apparatus is provided with a flow passage for discharging (evacuating) gas in a cavity for obtaining a cast product. The flow path spans a plurality of members constituting the vacuum casting apparatus. Here, when vacuuming is performed through the flow passage, if the atmosphere enters between the members, the degree of vacuum becomes insufficient. In order to avoid this, a sealing member such as an O-ring is interposed between the members. That is, the sealing member seals between the members and prevents the atmosphere from entering between the members.

The seal member is housed in a storage groove formed on one of the abutting members. By the way, in some cases, it is assumed that the accommodating groove is formed on the contact surface facing vertically downward. If the seal member is accommodated in the accommodating groove under this situation, there is a concern that the seal member may fall off. Patent Documents 1 to 4 propose techniques for avoiding this.

Jikkenhei No. 2-88060 Jikkenhei 4-127460 Japanese Unexamined Patent Publication No. 8-42700 Japanese Unexamined Patent Publication No. 2005-48790

As described in Patent Documents 1 to 4, in order to prevent the seal member from falling off according to the prior art, a protrusion is provided on the seal member or the accommodating groove, and an attempt is made to apply a predetermined tension to the seal member through the protrusion. It is a thing. In this case, since local compressive stress acts on the seal member, there is a concern that the seal member may break. In particular, in a vacuum casting apparatus in which the temperature of the member changes significantly as the molten metal is supplied to the cavity, it is presumed that the seal member is likely to break.

The present invention has been made to solve the above-mentioned problems, and it is possible to prevent the seal member from falling off even when the accommodating groove faces vertically downward, and the seal member breaks. It is an object of the present invention to provide a sealing structure and a method for manufacturing the same, which can dispel concerns.

In order to achieve the above object, according to one embodiment of the present invention, a first member having a first flow passage and having a first contact surface and a second flow passage connected to the first flow passage. Is formed and is interposed between the second member having the second contact surface facing the first contact surface to seal between the first member and the second member and the elastic member. In a seal structure including a seal member made of, the accommodating groove formed on either the first abutting surface or the second abutting surface and accommodating the sealing member is further included, and the accommodating groove includes the accommodating groove. The groove width, which has a first lateral inner wall on the inner peripheral side and a second lateral inner wall on the outer peripheral side, is the distance from the first lateral inner wall of the accommodating groove to the second lateral inner wall. A curved convex portion is provided, which is larger than the width of the seal member, protrudes from the second lateral inner wall toward the inside of the accommodating groove, and has a curved surface at the top that abuts on the seal member. A curved concave portion is formed so as to face the curved convex portion and to be depressed from the first lateral inner wall toward the outside of the accommodating groove, and the bottom portion separated from the sealing member is a curved surface. The portion of the lateral inner wall excluding the curved recess is a circle having a center of curvature that coincides with the center of the annular shape of the accommodating groove , and the nominal diameter of the sealing member is larger than the diameter of the first lateral inner wall. In addition to the tension based on the diameter difference between the nominal diameter of the seal member and the diameter of the circular first lateral inner wall, the curved convex portion is formed on the outer peripheral wall of the seal member. A tension is applied based on pressing, and the sum of the frictional resistance between the top of the curved convex portion and the sealing member and the frictional resistance between the first lateral inner wall and the sealing member. However, a seal structure that is set to be larger than the gravity acting on the seal member is provided.

According to yet another embodiment of the present invention, a first member having a first flow passage and having a first contact surface and a second flow passage connected to the first flow passage are formed and said first. 1 A sealing member made of an elastic member while interposing between a second member having a second contact surface facing the contact surface and sealing between the first member and the second member. A housing groove formed on either the first contact surface or the second contact surface and accommodating the seal member is included, and the accommodating groove includes a first lateral inner wall on the inner peripheral side and a second accommodating groove on the outer peripheral side. In the method for manufacturing a seal structure having a side inner wall, the groove width, which is the distance from the first side inner wall to the second side inner wall in which the seal member is housed, is compared with the width of the seal member. When forming the accommodating groove that is large and the seal member abuts on the first lateral inner wall, the frictional resistance between the seal member and the first lateral inner wall that the seal member abuts, and the said. The step of comparing the gravity acting on the seal member and the mold release resistance required to prevent the seal member from falling out of the accommodating groove when it is determined that the frictional resistance is smaller than the gravity. The step of obtaining, the step of setting the curved convex portion and the curved concave portion capable of imparting the mold release resistance, the first lateral inner wall, the curved concave portion, the second lateral inner wall, and the curved convex portion. The groove forming step of forming the accommodating groove and the accommodating step of accommodating the seal member in the accommodating groove formed by the groove forming step. The portion of the first lateral inner wall excluding the curved concave portion is formed into a circle having a center of curvature that coincides with the center of the annular shape of the accommodating groove, and the curved convex portion is formed from the second lateral inner wall. The top portion that protrudes inward toward the inside of the accommodating groove and abuts on the seal member is formed as a curved surface, and the curved concave portion faces the curved convex portion and is formed from the first lateral inner wall. The bottom portion that is recessed toward the outside of the accommodating groove and is separated from the sealing member is formed as a curved surface, and the nominal diameter of the sealing member is smaller than the diameter of the first lateral inner wall. In the accommodating step, by accommodating the sealing member in the accommodating groove, the curvature is added to the tension based on the diameter difference between the nominal diameter of the sealing member and the diameter of the circular first lateral inner wall. Provided is a method for manufacturing a seal structure, in which a tension based on the convex portion pressing the outer peripheral wall of the seal member is applied to the seal member.

According to the present invention, not only the lateral inner wall of the accommodating groove but also the top of the curved convex portion abuts on the seal member, thereby imparting sufficient frictional resistance (release resistance) to the seal member. Therefore, even when the seal member is accommodated in the accommodating groove that opens vertically downward, it is possible to prevent the seal member from falling off.

Further, even when it is difficult to change the groove width of the accommodating groove or the diameter of the side inner wall, it is possible to impart frictional resistance (release resistance) to the seal member by providing a curved convex portion. it can. Therefore, versatility is improved.

Moreover, since the top of the curved convex portion is curved, it is possible to avoid applying a local compressive stress to the sealing member. Therefore, the concern that the sealing member is broken is eliminated.

It is a schematic vertical sectional view of the main part of the vacuum casting apparatus provided with the seal structure which concerns on embodiment of this invention. It is a bottom view which showed the 2nd contact surface from the viewpoint from the vertical lower side. It is a schematic flowchart of the manufacturing method including the design method of the seal structure which concerns on embodiment of this invention. It is an enlarged view of the main part of FIG. It is a top view of the main part when forming the accommodating groove. It is a bottom view of the 2nd member which constitutes the seal structure which concerns on another Embodiment.

Hereinafter, the seal structure according to the present invention will be described in detail with reference to the accompanying drawings with reference to suitable embodiments in relation to the design method and the manufacturing method thereof.

FIG. 1 is a schematic vertical cross-sectional view of a main part of a vacuum casting apparatus provided with a seal structure 10 according to the present embodiment. This vacuum casting apparatus has a first member 12 located downward in the vertical direction and a second member 14 arranged above the first member 12. The first member 12 has a first contact surface 16, and the second member 14 has a second contact surface 18 that contacts the first contact surface 16. A first flow passage 20 opened at the first contact surface 16 is provided inside the first member 12, while a first flow passage 20 opened at the second contact surface 18 is provided inside the second member 14. A second flow passage 22 is provided.

The second flow passage 22 extends toward a cavity (not shown). That is, the first flow passage 20 communicates with the cavity via the second flow passage 22. An intake mechanism (not shown) is provided on the downstream side of the first flow passage 20 or the second flow passage 22. Therefore, after the mold is closed and the cavity is formed, the gas in the cavity is discharged from the second flow passage 22 through the first flow passage 20. As described above, the first flow passage 20 and the second flow passage 22 are exhaust passages for evacuating the cavity, and the pressure is negative while the evacuation is performed.

A substantially perfect circular accommodating groove 28 is formed on the second contact surface 18 facing vertically downward. The accommodating groove 28 includes a first lateral inner wall 30 on the inner peripheral side extending along the vertical direction, a ceiling wall 32 connected so as to be orthogonal to the first lateral inner wall 30, and the ceiling wall 32. It is a space having a substantially square cross section defined by the second lateral inner wall 34 on the outer peripheral side which is connected so as to hang down from the ceiling. Since the second contact surface 18 faces vertically downward, the accommodating groove 28 faces vertically downward and opens. The distance W1 from the first lateral inner wall 30 to the second lateral inner wall 34 (that is, the length of the ceiling wall 32) is defined as the groove width.

FIG. 2 is a bottom view showing the second contact surface 18 from a vertically downward viewpoint. The accommodating groove 28 accommodates a sealing member 38 as an O-ring that seals between the first contact surface 16 (first member 12) and the second contact surface 18 (second member 14). The sealing member 38 is made of an elastic body, and rubber is a typical material thereof.

The width W2 of the seal member 38 is slightly smaller than the groove width W1 of the accommodating groove 28, and the inner diameter (nominal diameter) d when the seal member 38 is not restrained in any way is the first side. It is slightly smaller than the diameter D of the inner wall 30. Therefore, when the seal member 38 is accommodated in the accommodating groove 28, the inner peripheral wall of the seal member 38 is pressed against the first lateral inner wall 30. As a result, a predetermined tension is applied to the seal member 38. The outer peripheral wall of the seal member 38 is separated from the second side inner wall 34.

Here, the second contact surface 18 is provided with curved portions 40 at five locations. The individual curved portions 40 are provided on the side of the curved convex portion 42 provided on the side of the second side inner wall 34 where the seal member 38 is separated from each other and on the side of the first lateral inner wall 30 where the seal member 38 abuts (pushes). It has a curved recess 44 that has been formed.

The first end portion (bottom portion) of the curved convex portion 42 connected to the second lateral inner wall 34 is curved so as to be depressed toward the outside of the accommodating groove 28, and has the same radius of curvature as R1. The arc portion 46 and the second arc portion 48 are formed. Further, the top 50 of the curved convex portion 42 protrudes toward the inside of the accommodating groove 28 (the first side inner wall 30 side) and is curved with a predetermined radius of curvature R2. The radius of curvature R1 of the first arc portion 46 and the second arc portion 48 is set smaller than the radius of curvature R2 of the top 50.

The top 50 of the curved convex portion 42 presses the seal member 38 from the outer peripheral wall side. In other words, the top 50 of the curved convex portion 42 abuts on the outer peripheral wall of the sealing member 38. Further tension is applied to the seal member 38 by this contact (pressing).

The curved concave portion 44 is formed so as to be recessed from the first lateral inner wall 30 toward the outside of the accommodating groove 28 at a position facing the curved convex portion 42, and the bottom portion thereof is the top portion of the curved convex portion 42. It is curved with the same radius of curvature R2 as 50. Due to this curvature, the bottom of the curved recess 44 is separated from the inner peripheral wall of the sealing member 38.

As described above, the inner peripheral wall of the seal member 38 abuts on the first lateral inner wall 30 of the accommodating groove 28 and is separated from the bottom of the curved recess 44. On the other hand, the outer peripheral wall of the seal member 38 is separated from the second lateral inner wall 34 of the accommodating groove 28 and abuts on the top 50 of the curved convex portion 42.

The seal structure 10 according to the present embodiment is basically configured as described above, and the effects thereof will be described next.

When assembling the vacuum casting apparatus, the sealing member 38 is accommodated in the accommodating groove 28. Since the nominal diameter d of the seal member 38 is slightly smaller than the diameter D of the first lateral inner wall 30, and the top portion 50 of the curved convex portion 42 presses against the seal member 38, a predetermined tension is applied to the seal member 38. Will be done. Here, at the base end portion of the curved convex portion 42, a first arc portion 46 and a second arc portion 48 that are depressed toward the outside of the accommodating groove 28 are formed. Therefore, the base end portion of the curved convex portion 42 is separated from the seal member 38. Therefore, when the seal member 38 is pushed into the accommodating groove 28, the base end portion of the curved convex portion 42 may come into local contact with the seal member 38, or the seal member 38 may be locally deteriorated due to this. Can be avoided.

When the vacuum casting apparatus is in the mold open state, the first member 12 and the second member 14 are separated from each other. At this time, the second contact surface 18 and the seal member 38 face vertically downward. Here, the seal member 38 is pressed against the first lateral inner wall 30 of the accommodating groove 28 and is pressed by the curved convex portion 42 as described above. For this reason, a predetermined tension is applied to the seal member 38, so that the seal member 38 is prevented from falling out of the accommodating groove 28.

When vacuum casting is performed by a vacuum casting apparatus, the molds that have been heated to a predetermined temperature are brought into contact with each other to form a cavity, and the molds are closed. At this time, heat is transferred to the first member 12 and the second member 14, the temperature rises, and the first contact surface 16 and the second contact surface 18 come into contact with each other. Therefore, the seal member 38 is interposed between the first contact surface 16 and the second contact surface 18.

Further, evacuation is performed to exhaust the gas in the cavity, and the gas flows into the first flow passage 20 through the second flow passage 22. At this time, the seal member 38 prevents the atmosphere from entering between the first contact surface 16 and the second contact surface 18. Therefore, the degree of vacuum in the cavity is sufficient.

As described above, according to the present embodiment, since the curved convex portion 42 is formed to apply sufficient tension to the seal member 38, the seal member 38 is held in the accommodating groove 28. Therefore, since the space between the first member 12 and the second member 14 is sufficiently sealed by the sealing member 38, the degree of vacuum in the cavity can be sufficiently increased. Moreover, since the base end portion of the curved convex portion 42 is curved so as to be depressed toward the outside of the accommodating groove 28, local stress is applied to the sealing member 38 when the sealing member 38 is pushed into the accommodating groove 28. Is avoided. As a result, the partial deterioration of the seal member 38 is prevented from progressing.

Next, a manufacturing method including a design method of the seal structure 10 for setting the number of curved portions 40 and the like will be described. As shown in the schematic flow in FIG. 3, the design method includes a comparison step S1, an evaluation step S2, and a setting step S3, and the manufacturing method includes a curved convex portion 42 and a curve set based on the design method. Further, it has a processing step S4 for forming the recess 44.

In the comparison step S1, the gravity F1 acting on the seal member 38 and the frictional resistance between the seal member 38 and the first lateral inner wall 30 are compared. Specifically, when the mass of the seal member 38 is m1, the normal force due to the tension acting on the seal member 38 is N, and the frictional resistance is F2, the following equations (1) and (2) hold. In addition, g in the formula (1) represents the gravitational acceleration, and μ in the formula (2) represents the friction coefficient.
F1 = m1 × g ... (1)
F2 = μN ... (2)
In order to prevent the seal groove from falling off from the accommodating groove 28 facing vertically downward, it is necessary to set F2 larger than F1.

Assuming that the spring constant of the sealing member 38, which is an elastic body, is k, the equation (2) is transformed into the following equation (3).
F2 = μ × {(D−d) / 2} × k × π… (3)
As can be understood from this equation (3), when the sealing member 38 having a large nominal diameter d, and thus the peripheral length and mass m1, is used, the gravity F1 becomes large and the frictional resistance F2 becomes small. Therefore, the seal member 38 tends to easily fall off from the accommodating groove 28.

Comparing the gravity F1 obtained from the equations (1) and (3) with the frictional resistance F2, when F2 is smaller than F1, a first lateral inner wall 30 having a nominal diameter d larger than the design value is formed, and the frictional resistance It is recalled to increase F2. However, in many cases, the groove width W1 of the accommodating groove 28 and the diameter D of the first side inner wall 30 cannot be changed from the design values due to restrictions on the layout of the vacuum casting apparatus.

Therefore, when the frictional resistance F2 is lower than the gravity F1, in the evaluation step S2, the tension to be applied from the curved convex portion 42 to the seal member 38 in order for the frictional resistance F2 to exceed the gravity F1 is obtained as follows. That is, when the curved convex portion 42 is provided, the top portion 50 abuts on the outer peripheral wall of the seal member 38 from the point L1 to the point L2, as shown in an enlarged view of FIG. Assuming that the amount of depression (pushing amount) of the seal member 38 at this time is dL, the release resistance F3 of the pushed portion is represented by the following equation (4).

Here, the curved recess 44 is separated from the inner peripheral wall of the seal member 38 and is not in contact with the inner peripheral wall. Therefore, the curved recess 44 does not contribute the mold release resistance to the seal member 38. Assuming that the length of the arc of the curved recess 44 is L3 and the number of curved portions 40 to be provided is n, the total release resistance F _all can be obtained by the following equation (5).

If the total release resistance F _all exceeds the gravity F1, it is possible to prevent the seal member 38 from falling out of the accommodating groove 28 due to the action of gravity. Therefore, next, in the setting step S3, the curved convex portion 42 and the curved concave portion 44 in which the pushing amount dL, the distance from the point L1 to the point L2, and the length L3 are set so that _{F all satisfies such a condition.} To set.

However, if the pushing amount is excessively large, the seal member 38 is locally deteriorated. In order to avoid this, it is preferable to set the height of the curved convex portion 42 so that the pushing amount is 8 to 20%. Here, 100% corresponds to the width W2 of the seal member 38. Therefore, for example, when the pushing amount is 10%, dL in FIG. 4 corresponds to 10% of the width W2. It is more preferable to set the height of the curved convex portion 42 so that the pushing amount is 10 to 15% in the constituent members of the device such as a vacuum casting device in which the temperature rises and falls repeatedly.

By setting the pushing amount (dL) as described above, the distance and length L3 from the point L1 to the point L2 that can satisfy the equation (5) can be easily set.

For example, in the seal member 38 having a width of 5.7 mm and a nominal diameter of 170 mm, the gravity F1 and the frictional resistance F2 when the curved portion 40 is not provided are about 250N and 175N, respectively. Therefore, there is a concern that the seal member 38 may fall off from the accommodating groove 28. On the other hand, when the distance from the point L1 to the point L2 is set so that the pushing amount is within the range of 10 to 15% as described above and the number of the curved portions 40 is 5, the mold is completely released. The resistance F _all exceeds 400N. That is, it exceeds 250 N of gravity F1. Therefore, since the seal member 38 is well held in the accommodating groove 28, the concern that the seal member 38 may fall off from the accommodating groove 28 is eliminated. The radius of curvature R2 at this time is about 25 to 30.

As described above, according to the present embodiment, even when sufficient frictional resistance cannot be obtained from the seal member 38 with the simple circular groove, the seal member 38 can be provided by providing one or more curved portions 40. The total release resistance F _all can be increased. This is because the top portion 50 of the curved convex portion 42 abuts on the outer peripheral wall of the seal member 38 to apply tension to the seal member 38.

Next, the processing step S4 for providing the curved portion 40 is performed. That is, as shown in FIG. 5, the machining tool 60 for forming the accommodating groove 28 is meandered at the place where the curved portion 40 is provided. For this purpose, the profile regarding the movement locus of the machining tool 60 may be slightly changed from the profile for forming the circular groove. By doing so, the accommodating groove 28 in which the curved portion 40 is interposed can be easily formed.

Further, due to this meandering, a first arc portion 46 and a second arc portion 48 having a radius of curvature R1 smaller than the radius of curvature R2 of the top portion 50 are formed at the base end portion of the curved convex portion 42.

The present invention is not particularly limited to the above-described embodiment, and various modifications can be made without departing from the gist of the present invention.

For example, in this embodiment, exhaust is performed from the first flow passage 20 and the second flow passage 22, but the compressed fluid is supplied through the first flow passage 20 and the second flow passage 22. It may be. In this case, the seal member 38 prevents the compressed fluid from leaking from between the first contact surface 16 and the second contact surface 18.

FIG. 6 shows a housing groove 72 included in the seal structure 70 according to this embodiment. In this embodiment, the inner peripheral wall of the seal member 38 is separated from the first side inner wall 30, and the outer peripheral wall is in contact with the second side inner wall 34. The curved portion 74 is provided so that the curved convex portion 42 projects from the first lateral inner wall 30 toward the inside of the accommodating groove 72, and the curved concave portion 44 is provided from the second lateral inner wall 34 to the accommodating groove 72. It is provided so as to sink toward the outside of.

Also in this form, the total release resistance F _all is obtained in the same manner as described above. Based on this value, the number of curved portions 40, the radius of curvature R2, and the like can be obtained by further setting the pushing amount (dL) of the sealing member 38 by the top 50 of the curved convex portion 42 within a predetermined range. .. However, in this case, the diameter D'of the second side inner wall 34 of the accommodating groove 28 is subtracted from the nominal diameter d of the seal member 38.

Further, the target for providing the seal structures 10 and 70 is not particularly limited to the vacuum casting apparatus. Further, it goes without saying that the surface on which the seal structures 10 and 70 are provided is not limited to the surface facing vertically downward.

10, 70 ... Seal structure 12 ... First member 14 ... Second member 16 ... First contact surface 18 ... Second contact surface 20 ... First flow passage 22 ... Second flow passage 28, 72 ... Storage groove 30 ... 1st lateral inner wall 34 ... 2nd lateral inner wall 38 ... Sealing members 40, 74 ... Curved portion 42 ... Curved convex portion 44 ... Curved concave portion 46 ... 1st arc portion 48 ... 2nd arc portion 50 ... Top

Claims (4)

A first member having a first flow passage and having a first contact surface and a second flow passage connected to the first flow passage are formed and a second contact surface is opposed to the first contact surface. In a sealing structure configured by interposing between a second member having a contact surface to seal between the first member and the second member and including a sealing member made of an elastic member.
A housing groove formed on either the first contact surface or the second contact surface and accommodating the seal member is further included.
The accommodating groove has a first lateral inner wall on the inner peripheral side and a second lateral inner wall on the outer peripheral side.
The groove width, which is the distance from the first lateral inner wall of the accommodating groove to the second lateral inner wall, is larger than the width of the sealing member.
A curved convex portion is provided so as to project from the second lateral inner wall toward the inside of the accommodating groove and the top portion abutting the seal member is a curved surface.
A curved concave portion is formed so as to face the curved convex portion and to be depressed from the first lateral inner wall toward the outside of the accommodating groove, and the bottom portion separated from the sealing member is a curved surface.
The portion of the first lateral inner wall excluding the curved recess is a circle having a center of curvature that coincides with the center of the annular shape of the accommodating groove.
The nominal diameter of the sealing member is smaller than the diameter of the first lateral inner wall.
In the sealing member, in addition to the tension based on the diameter difference between the nominal diameter of the sealing member and the diameter of the circular inner wall of the first side, the curved convex portion presses the outer peripheral wall of the sealing member. The tension is given based on
The sum of the frictional resistance between the top of the curved convex portion and the sealing member and the frictional resistance between the first lateral inner wall and the sealing member is compared with the gravity acting on the sealing member. Largely set seal structure. In the seal structure according to claim 1, an arc portion recessed toward the outside of the accommodating groove is formed at the base end portion of the curved convex portion, and the radius of curvature of the arc portion becomes the radius of curvature of the top portion. Seal structure set smaller than that. A first member having a first flow passage and having a first contact surface and a second flow passage connected to the first flow passage are formed and a second contact surface is opposed to the first contact surface. A sealing member made of an elastic member and a sealing member formed of an elastic member, which is interposed between the second member having a contact surface and seals between the first member and the second member, and the first contact surface or the second contact surface. In a method for manufacturing a seal structure, which includes a storage groove formed in any of the above and accommodating the seal member, and the accommodating groove has a first lateral inner wall on the inner peripheral side and a second lateral inner wall on the outer peripheral side.
The groove width, which is the distance from the first side inner wall to the second side inner wall in which the seal member is housed, is larger than the width of the seal member, and the seal member is on the first side inner wall. A step of comparing the frictional resistance between the seal member and the first lateral inner wall with which the seal member abuts and the gravity acting on the seal member when forming the accommodating groove with which the seal member abuts.
When it is determined that the frictional resistance is smaller than the gravity, the step of obtaining the mold release resistance necessary to prevent the sealing member from falling out of the accommodating groove, and the step of obtaining the mold release resistance.
A step of setting a curved convex portion and a curved concave portion capable of imparting the mold release resistance, and
A groove forming step of forming the accommodating groove having the first lateral inner wall, the curved concave portion, the second lateral inner wall, and the curved convex portion.
The accommodating step of accommodating the seal member in the accommodating groove formed by the groove forming step, and the accommodating step.
Have,
In the groove forming step, the portion of the first lateral inner wall of the accommodating groove excluding the curved recess is formed into a circle having a center of curvature that coincides with the center of the annular shape of the accommodating groove, and the curved convexity is formed. The portion is formed so as to project from the second lateral inner wall toward the inside of the accommodating groove so that the top portion in contact with the seal member is a curved surface, and the curved concave portion is formed into the curved convex portion. Along with facing each other, the bottom portion that is recessed from the first lateral inner wall toward the outside of the accommodating groove and is separated from the sealing member is formed as a curved surface.
The nominal diameter of the sealing member is smaller than the diameter of the first lateral inner wall.
In the accommodating step, by accommodating the sealing member in the accommodating groove, the curvature is added to the tension based on the diameter difference between the nominal diameter of the sealing member and the diameter of the circular first lateral inner wall. A method for manufacturing a seal structure, in which a tension based on the convex portion pressing the outer peripheral wall of the seal member is applied to the seal member. In the manufacturing method according to claim 3, an arc portion having a radius of curvature smaller than the radius of curvature of the top portion and being depressed toward the outside of the accommodating groove is formed at the base end portion of the curved convex portion. Manufacturing method of seal structure.

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