JP2000238080A - Injection molding method and rotation detecting device manufactured using the same - Google Patents

Abstract

(57) [Problem] To reduce the size of a rotation detecting device by preventing resin from entering the inner peripheral side of a coil or the like. The metal cover 4 is fixed to the fixed mold 21. Then, after disposing the assembly in the metal cover 4, the movable mold 22b is inserted so that the distal end of the movable mold 22b fits into the inner periphery of the assembly including the coil 11, the coil spool 12, and the like.
To move. Thereafter, the resin is injected from the tip of the movable mold 22b to injection-mold the resin mold portion 15. At this time, in the step of disposing the aggregate, the protruding portions 12a provided on the entire inner circumference of the substantially annular aggregate are connected to the metal cover 4.
In the step of moving the movable mold 22a, the projecting portion is stress-deformed by the distal end of the movable mold 22b, so that the outer periphery of the distal end of the movable mold 22b and the inner periphery of the assembly are Be sure to seal between them. Specifically, the projecting portion 12a is formed by projecting the coil spool 12 to the inner peripheral side of the assembly.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an injection molding method and an apparatus manufactured by using the method, for example, a method of electromagnetically detecting the rotational state of a subject based on a rotor that rotates in accordance with the rotation of the subject. The present invention relates to a rotation detecting device.

[0002]

2. Description of the Related Art As a rotation detecting device for electromagnetically detecting the rotation state of a subject based on a rotor that rotates in accordance with the rotation of the subject, the present applicant has previously disclosed Japanese Patent Application No. 10-18508.
No. 6 has been filed. This rotation detection device is shown in FIG.
This rotation detecting device includes a rotor 3 and a rotor switch section 8 in which a large number of portions having different magnetic resistances are alternately arranged so as to be surrounded by the rotor 3. Cores 9A and 9B and permanent magnet 11 forming a closed magnetic circuit included in a part thereof, and electromagnetic coil 11 for converting a change in magnetic flux amount of the closed magnetic circuit into an alternating current
And the like are provided integrally with a mold resin 15.

The rotor 3 and the rotor switch section 8 and the sensor body 6 are formed separately, and the rotor 3 and the rotor switch section 8 are fixed to the rotating shaft 2 and rotate with the subject. The sensor body 6 is held at a position facing the rotor 3 and the rotor switch section 8 via the bearing 5 so as not to rotate with the subject.

[0004] In this rotation detecting device, the sensor main body 6 is held in a metal cover 4 such that the sensor main body 6 is held at a position facing the rotor 3 and the rotor switch section 8.
The sensor body 6 is arranged at the above-mentioned position by fitting and fixing the metal cover 4 into the recess of the housing 5 a provided in the bearing 5.

At this time, prior to fixing the sensor body 6 and the metal cover 4 to the bearing 5, the sensor body 6
The components (the rotor switch unit 8, the cores 9A, 9A,
B, the coil 11 and the like) are arranged in the metal cover 4 and then injection-molded so that each component is resin-molded at a predetermined position in the metal cover 4.

[0006]

The above-mentioned injection molding will be specifically described. FIG. 7 shows an injection molding process, and the above description will be made based on this drawing. First, the metal cover 4 is prepared, and the metal cover 4 is arranged in the fixed mold 21. Then, the rotor switch section 8, the cores 9A and 9B, the permanent magnet 10, the coil 11, and the like are accommodated in the metal cover 4. As a result, the assembly of the components is arranged at a predetermined position on the metal cover 4 in a state of forming a substantially annular outer shape.

Thereafter, the movable mold 22 is moved. At this time, even if the displacement occurs, the movable mold 22 is moved so that the tip of the movable mold 22 can pass through each of the components (the rotor switch portion 8, the cores 9A and 9B, and the coil 11) formed in a substantially annular shape. The outer diameter of the tip of the movable mold 22 is made smaller than the inner diameter of the assembly formed by each component, so that a gap is formed between the outer circumference of the tip of the movable mold 22 and the inner circumference of the assembly. Size is set.

In this way, by injecting the resin from the movable injection hole, each component is resin-molded to form the sensor body 6 and the sensor body 6 is attached to the metal cover 4. Is fixed. However, as described above, since a gap is provided between the outer periphery of the movable mold 22 and the inner periphery of the assembly of each component, the resin injected through this gap collects as shown by the arrow in the drawing. The resin penetrates into the inner circumference of the body, and the mold resin is disposed on the inner circumference of the assembly (see FIG. 6). Therefore, the inner diameter of the aggregate is reduced by the amount corresponding to the arrangement of the mold resin. Metal cover 4 for bearing 5
When the assembly is assembled, the tip of the bearing nut 7 is fitted into the inner peripheral side of the assembly, so that the diameter of the inner periphery of the assembly needs to be a size that allows the tip of the bearing nut 7 to be fitted. As the resin enters, the diameter of each component must be increased. For this reason, there is a problem that the diameters of the respective components such as the rotor switch section 8, the cores 9A and 9B, the coil 11, and the like become large, and that the rotation detection device as a whole becomes large.

The present invention has been made in view of the above problems, and has as its first object to reduce the size of a rotation detecting device. Also,
A second object is to provide an injection molding method suitable for realizing miniaturization of an apparatus.

[0010]

In order to achieve the above object, the following technical means are employed. According to the first aspect of the present invention, a metal cover (4) is prepared,
Fixing the metal cover to the fixed mold (21), arranging the aggregate in the metal cover, and moving the metal mold (22).
b) moving the movable mold so that the tip of the assembly fits into the inner periphery of the assembly; and injecting resin from the tip of the movable mold using the metal cover as a part of the mold to form a resin member. (1
5) Injecting molding, and in the step of arranging the assembly, the projecting portion (12a) provided on the entire inner periphery of the substantially annular assembly is arranged on the metal cover, and the movable mold is mounted. In the moving step, the protrusion is stress-deformed by the tip of the movable die, so that the protrusion seals between the outer periphery of the tip of the movable die and the inner periphery of the assembly.

As described above, the projection is provided on the entire inner periphery of the assembly, and the tip of the movable mold deforms the projection by stress. It can be made to seal between the inner circumference. Accordingly, the movement of the resin can be restricted by the protruding portion, and the resin can be prevented from entering the inner peripheral side of the assembly. This makes it possible to reduce the size of the entire rotation detecting device.

For example, as in the invention described in claim 3,
The projecting portion can be formed by projecting the coil spool in the radial direction of the assembly. Further, as in the invention according to claim 4, a stepped portion is formed in the movable mold, and when the projecting portion is stress-deformed by the pressure of the resin during the injection molding step, the stepped portion is formed at the stepped portion. The seal may be formed by regulating the stress deformation of the portion.

[0013] When the fixed projection is fitted into the inner periphery of the assembly, the projection is stress-deformed by the projection. Alternatively, the above sealing may be performed. Such claim 1
According to the method for manufacturing a rotation detecting device according to any one of (1) to (4), as set forth in claim 5 or 6, a projection is provided on the entire inner circumference of the substantially annular aggregate, and It is possible to manufacture a rotation detecting device in which a portion located on the inner periphery of the body is terminated by a protrusion.

[0014] In the invention according to claim 7, the step of disposing the frame-shaped body in the fixed mold, and moving the movable mold so that the tip end of the movable mold fits into the inner periphery of the frame-shaped body. And a step of injecting a resin from the tip of the movable mold to injection-mold the resin member. In the step of arranging the frame, the projecting portion (12a) provided on the entire inner circumference of the frame is provided. In the step of disposing the movable mold in the fixed mold and moving the movable mold, the projecting section is stress-deformed by the tip of the movable mold, so that the outer periphery of the movable mold tip and the inside of the frame-like body are formed at the projecting section. It is characterized by sealing between the circumference.

In this manner, the projecting portion is stress-deformed by the tip of the movable mold, and the projecting portion seals between the outer periphery of the tip of the movable mold and the inner periphery of the frame. By doing so, it is possible to prevent the resin from entering during this time, so that the size of the device formed by injection molding can be reduced. When the fixed projection is fitted into the inner periphery of the assembly as described in claim 7, the projection is stress-deformed by the projection, so that the sealing is achieved. May be performed.

[0016] As described in claim 8, the protruding portion is
A part of the frame can be formed so as to protrude in the inner circumferential direction of the frame. According to a ninth aspect of the present invention, a stepped portion is formed on the movable die, and when the projecting portion is stress-deformed by the pressure of the resin during the injection molding process, the stepped portion is formed by the stepped portion. The seal may be formed by regulating the stress deformation.

The above-mentioned reference numerals in parentheses indicate the correspondence with specific means described in the embodiment described later.

[0018]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing a first embodiment of the present invention. FIG. 1 is a cross-sectional view illustrating a configuration of a rotation detection device according to an embodiment of the present invention. The rotation detection device 1 is applied to, for example, a wheel speed sensor that detects the rotation speed of a driven wheel (not shown) of a vehicle.

The rotation detecting device 1 is fixed to a rotor 3 fixed to a rotating shaft 2 of a driven wheel, and to a housing 5a provided in a bearing 5 via a metal cover 4, and the rotor 3
And a sensor body (detection unit) 6 for detecting the rotation speed of the sensor. The rotor 3 rotates together with the rotating shaft 2, and the sensor body 6 is held rotatably with respect to the rotating shaft 2 via a bearing 5. Thus, even when the rotor 3 rotates with the rotation shaft 2, the sensor main body 6 does not rotate with the rotation shaft 2.

The rotor 3 has a cylindrical shape along the outer periphery of the rotating shaft 2 and is arranged so as to protrude in the direction of the bearing nut 7. The protruding portion of the rotor 3 has a column (a portion having a low magnetic resistance) and a window (a portion having a high magnetic resistance) of a magnetic material alternately formed at predetermined intervals along the rotation direction of the rotor 3. ), And these constitute the rotor switch section 8. These windows and pillars together with the sensor body 6 form a closed magnetic circuit, and serve as a switch for changing the amount of magnetic flux in the magnetic circuit.

The sensor body 6 is provided with a portion that is fitted on the inner peripheral side of the rotor switch section 8, and has the following configuration. First core 9A and second core 9B bent so as to face rotor switch section 8
Are arranged coaxially with the rotating shaft 2 and are each formed in a disk shape. These first core 9A and second core 9B
Inside the first core 9, a flat permanent magnet 10 and a coil spool 12 around which a coil 11 is wound are provided.
A, 9B. Further, a metal ring member 13 is disposed on the inner peripheral side of the coil 11 and the coil spool 12.
The first core 9A and the second core 9B form a magnetic circuit.

The coil spool 12 is made of a substantially annular resin, has a substantially annular outer peripheral surface formed with a groove surrounding the outer periphery, and has a U-shaped cross section with an open outer peripheral surface. . The coil 11 is wound in this groove. Further, a protruding portion 12 a is formed on the inner peripheral surface side of the coil spool 12 so as to extend around the inner periphery of the coil spool 12. That is, the diameter of the inner peripheral surface of the coil spool 12 is partially reduced by the protrusion 12a. The protruding portion 12a is configured to become thinner toward the tip. It should be noted that, with the center line of the coil spool 12 formed in a substantially annular shape as the axis, this axis is arranged coaxially with the rotating shaft 2.

Further, an output terminal 14 is connected to the coil 11, and connection to the outside is made through the output terminal 14. This external terminal 14 is fitted and fixed to the coil spool 12. These first and second cores 9A and 9B, coil 11, coil spool 1
2. Ring member 13, output terminal 14, and permanent magnet 10
Is a resin (for example, polybutylene terephthalate (PB)
T)) is molded and integrated. What is integrated by the resin mold portion 15 constitutes the sensor main body 6.

The resin mold section 15 is formed by injection molding. The end of the recess is terminated at the tip of the protrusion 12a of the coil spool 12. That is, the core 9A,
9B, coil 11, coil spool 12, ring member 1
3, the portion facing the tip of the bearing nut 7 is a concave portion, and the inner periphery of a substantially annular assembly formed by the ring member 13, the output terminal 14, and the permanent magnet 10 The mold resin of the resin mold portion 15 does not enter the portion, and the inner peripheral portion is exposed.

In the sensor main body 6, the first and second magnetic switches 9a and 9b provided on the first and second cores 9A and 9B, respectively, that is, the surfaces facing the rotor switch 8 are: It is configured to be exposed from the resin mold portion 15. These magnetic switches 9a, 9
b has a claw shape in which the magnetic portion and the space portion are alternately continuous in the circumferential direction.

The resin mold section 15 is provided with the output terminal 1.
4 has a protruding shape at the portion where it is arranged. The cover-shaped metal cover 4 is provided so as to cover the sensor body 6 configured as described above, and an adhesive or the like provided between the resin mold portion 15 and the metal cover 4 is used.
The sensor body 6 and the metal cover 4 are fixed.

The metal cover 4 has an opening 4a formed of a cylindrical projection. The output terminal 14 is fitted into the opening 4a so that external connection can be made. A part of the metal cover 4 is
The sensor main body 6 is fixed to the housing 5a by being fitted into the concave portion of FIG.

In the rotation detecting device 1 thus configured, a closed magnetic circuit is formed by the permanent magnet 10, the first core 9B, the column of the rotor switch unit 8, the second core 9A, and the ring member 13. You. When the magnetic switches 9a and 9b of the first and second cores 9A and 9B face the window of the rotor switch 8, a closed magnetic circuit is provided in two places of the magnetic switches 9a and 9b. And are disconnected at the same time.
Then, a current is generated in the coil 11 in accordance with the amount of magnetic flux passing through the closed magnetic circuit that changes in this way, and this current is transmitted to the analysis means (not shown) through the output terminal 14. In this analysis means, the rotational speed of the rotating shaft is detected from the current change state (frequency change), and the wheel speed of the driven wheel is detected based on the detected rotational speed.

Next, the manufacturing process of the rotation detecting device shown in FIG. 1 is shown in FIGS. 2 and 3, and a method of manufacturing the rotation detecting device will be described with reference to these drawings. FIGS. 4A to 4C are partially enlarged views of the vicinity of the protruding portion during the step shown in FIG. [Step shown in FIG. 2] First, the metal cover 4 is attached to the first and second cores 9A and 9 constituting the sensor body 6 (see FIG. 1).
B, coil 11, coil spool 12, output terminal 14,
The permanent magnet 10 and the ring member 13 are put into the fixed mold 21 together with the permanent magnet 10.

[Step shown in FIG. 3]
Are fitted on the outer circumferences of the first and second cores 9A and 9B, and the movable mold 22b is moved to a predetermined position, specifically, the movable mold 22.
b is moved to a position where a part of the front end portion passes through the protruding portion 12a and further enters the inside of the metal cover 4.

At this time, since the outer diameter of the tip of the movable die 22b is larger than the inner diameter of the protruding portion, the movable die 22b is inserted into the protruding portion 12a by press fitting. The situation at this time is shown in FIGS. 4 (a) and 4 (b). As shown in these figures, first, the movable mold 22b is
Before being press-fitted into a, the protruding portion 12a is in a state without bending (FIG. 4A). And the movable mold 22b
Is pressed into the protruding portion, the protruding portion 12a
The movable die 22b is bent in the direction of insertion (downward in the drawing) by the force applied from FIG. 4B (FIG. 4B).

Thereafter, the resin mold portion 15 shown in FIG. 1 is formed by injection molding. Specifically, the resin is injected at a temperature of 250 ° C. or more and a pressure of 20 MPa or more. Thereby, the first and second cores 9 are formed in the resin mold portion 15.
A and 9B, the coil 11, the coil spool 12, the ring member 13, the output terminal 14, and the permanent magnet 10 are molded and integrated. At this time, as shown in FIG. 4C, the protruding portion 12a bends due to the pressure of the injected resin, and the resin attempts to move outward from the protruding portion 12a by pushing the protruding portion 12a. The protruding portion 12a comes into contact with the stepped portion 22c formed at the distal end of the protruding portion 22b, so that the resin is restricted from moving outside the protruding portion 12a. As a result, the space between the outer periphery of the movable mold 22b and the inner periphery of the assembly is sealed by the seal protruding portion 12a, and the resin mold portion 15 is terminated at the tip end position of the protruding portion 12a.
And the sensor body 6 and the metal cover 4 are integrated.

As described above, the outer periphery of the tip of the movable mold 22b is covered with the protrusion 12a, and the resin injected from the protrusion 12a is prevented from moving toward the inner periphery of the assembly. The size of the entire rotation detecting device can be reduced. (Second Embodiment) In the above embodiment, the case where the injection molding method is applied to the rotation detecting device has been described. In the present embodiment, the outer shape of the magnet and the shaft of the magnet rotor for adjusting the damping force of the shock absorber are injected. The case of forming by molding will be described.

FIG. 5 is a cross-sectional view when the shaft 51 of the magnet rotor and the magnet 52 are injection-molded. A substantially cylindrical shaft 51 is provided in a magnet 52 having a substantially cylindrical shape.
Are inserted, and the magnet 52 and the shaft 51 are integrally formed of a resin 53. A protruding portion 51a is formed on the inner peripheral portion of the shaft 51 so as to protrude from the inner periphery. During the injection molding, the protruding portion 51a comes into contact with the outer periphery of the distal end of the movable mold, and A seal is provided between the inner periphery and the movable mold. For this reason, as shown in FIG.
3 has not entered.

As described above, the present invention can be applied to the injection molding of the shaft 51 of the magnet rotor and the magnet 52. (Other Embodiments) In the first embodiment, the projecting portion 12a is provided on the coil spool 12 to prevent the resin from entering the inner periphery of the assembly constituted by the components of the sensor main body 6. , Coil spool 12
It does not have to be integrated with. For example, a member forming the protruding portion 12a may be separately configured, or a burr may be formed on the inner periphery of the ring member 13 to form the protruding portion 12a.

In the first embodiment, the protrusion 12
Although the resin is prevented from moving outside the protruding portion 12a by restricting the deflection of the protruding portion a by the stepped portion 22c of the movable mold 22b, such an effect can be obtained even by sealing only the protruding portion 12a. Is possible. Also in the second embodiment, the protrusion may be provided in a configuration different from the shaft.

In the above embodiment, the case where the tip of the movable mold 22b is brought into contact with the inner periphery of the assembly has been described. However, the fixed mold 21 is provided with a projection, and the projection is The protrusion 12a may be stress-deformed by contacting the inner periphery. For example, it can be realized by first disposing the assembly in the fixed mold 21 and then moving the assembly together when moving the movable mold 22b so that the convex portion is fitted into the inner periphery of the assembly. .

In the first embodiment, the case where the injection molding method according to the embodiment of the present invention is applied to the case where the rotation detecting device is injection-molded in the second embodiment, and the case where the shaft of the magnet rotor and the magnet are injection-molded in the second embodiment. , Can be applied to other devices.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a rotation detection device to which an embodiment of the present invention has been applied.

FIG. 2 is a diagram for explaining a manufacturing process of the rotation detecting device shown in FIG.

FIG. 3 is a view for explaining a manufacturing process of the rotation detecting device following FIG. 2;

FIG. 4 is an enlarged view of the vicinity of a protruding portion during the step shown in FIG. 2;

FIG. 5 is a cross-sectional view of a second embodiment of the present invention when a shaft of a magnet rotor and a magnet are injection-molded.

FIG. 6 is a cross-sectional view of a rotation detection device previously filed by the present applicant.

FIG. 7 is a diagram showing the rotation detecting device shown in FIG. 6 during injection molding.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Rotation detection apparatus, 2 ... Rotating shaft, 3 ... Rotor, 4 ... Metal cover, 5 ... Bearing, 5a ... Housing, 6 ... Sensor main body, 7 ... Bearing nut, 8 ... Rotor switch part, 9A, 9B ... No. DESCRIPTION OF SYMBOLS 1, 2nd core, 10 ... permanent magnet, 11 ... coil, 12 ... coil spool, 13 ... ring member, 14 ... output terminal, 15 ... resin mold part, 51
... Shaft, 51a ... Tip, 52 ... Magnet, 53 ... Resin.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) // B29L 31:08

Claims (10)

[Claims] 1. A magnetic flux path section (9A, 9B, 1) in which a magnetic resistance is changed by a rotor switch section (8) in which portions having different magnetic resistances are alternately switched according to the rotation of a subject.
3), a magnet (10) for generating a magnetic flux in the magnetic flux passage, an electromagnetic coil (11) for generating a current according to a change in magnetic flux in the magnetic flux passage, and a coil spool around which the electromagnetic coil is wound And (12) a method of manufacturing a rotation detecting device including a sensor body (6) obtained by molding a substantially frame-shaped assembly including a resin member (15), the assembly comprising: Arranging the body, so that the tip of the movable mold fits into the inner periphery of the assembly,
A step of moving the movable mold; and a step of injecting a resin from a tip end of the movable mold to injection-mold the resin member. In the step of arranging the aggregate, the aggregate having a substantially frame shape is provided. In the step of disposing a protruding portion (12a) provided on the entire inner circumference of the fixed die in the fixed die, and moving the movable die, the protruding portion is stress-deformed by a tip end of the movable die, thereby forming the protruding portion. A method for manufacturing a rotation detecting device, characterized in that a gap is sealed between an outer periphery of a tip portion of the movable die and an inner periphery of the assembly. 2. A magnetic flux passage section (9A, 9B, 1) in which a magnetic resistance is changed by a rotor switch section (8) in which portions having different magnetic resistances alternately change according to the rotation of the subject.
3), a magnet (10) for generating a magnetic flux in the magnetic flux passage, an electromagnetic coil (11) for generating a current according to a change in magnetic flux in the magnetic flux passage, and a coil spool around which the electromagnetic coil is wound (12) In the method for manufacturing a rotation detecting device provided with a sensor body (6) obtained by molding a substantially frame-shaped assembly including the resin member (15), the convex portion is provided. A step of disposing the assembly in a stationary mold; a step of moving a movable mold; and a step of injecting a resin into the movable mold and the fixed mold to injection-mold the resin member; In the step of disposing, the projecting portion (12a) provided on the entire inner circumference of the aggregate having a substantially frame shape is disposed in the fixed mold, and in the step of moving the movable mold, the movable mold is moved together with the movable mold. Move the assembly and The projection is fitted into the inner periphery of the united portion, and the projection is stress-deformed by the projection. A method for manufacturing a rotation detecting device, wherein a seal is provided between the rotation detecting device and an inner periphery. 3. The method according to claim 1, wherein the projecting portion is formed by projecting the coil spool in an inner circumferential direction of the assembly. 4. A stepped portion is formed on the movable mold, and when the projecting portion undergoes stress deformation due to the pressure of the resin during the injection molding step, the stress of the projecting portion is generated at the stepped portion. The method according to claim 1, wherein the deformation is regulated. 5. A magnetic flux passage section (9A, 9B, 1) in which a magnetic resistance is changed by a rotor switch section (8) in which portions having different magnetic resistances alternately change according to the rotation of the subject.
3), a magnet (10) for generating a magnetic flux in the magnetic flux passage, an electromagnetic coil (11) for generating a current according to a change in magnetic flux in the magnetic flux passage, and a coil spool around which the electromagnetic coil is wound (12) is provided with a sensor main body (6) formed by molding a resin member (15) with an assembly comprising: (a) a protruding portion (12a) on the entire inner circumference of the assembly having a substantially frame shape.
Wherein a portion of the resin member located on the inner periphery of the assembly terminates at a tip of the protruding portion. 6. The rotation detecting device according to claim 5, wherein the projecting portion is configured to project the coil spool in an inner circumferential direction of the assembly. 7. A step of disposing a frame-shaped body in a fixed mold, and a step of fitting a movable mold tip to an inner periphery of the frame-shaped body.
Moving the movable die; and injecting a resin from a tip end of the movable die to injection-mold the resin member. In the step of disposing the frame, the entire inner periphery of the frame is In the step of disposing a protrusion (12a) provided on the circumference in the fixed mold and moving the movable mold, the protrusion is stress-deformed by a tip end of the movable mold, so that the protrusion is deformed by the protrusion. An injection molding method, characterized in that a seal is provided between the outer periphery of the tip of the movable die and the inner periphery of the frame. 8. A step of disposing a frame-shaped body in a fixed mold, a step of moving a movable mold, and a step of injecting a resin into the movable mold and the solid mold to injection-mold the resin member. In the step of arranging the frame, the protrusion (12a) provided on the entire inner periphery of the frame is arranged in the fixed mold, and in the step of moving the movable mold, the movable mold is moved. And moving the assembly so that the protrusion is fitted into the inner periphery of the assembly, and the protrusion deforms the protrusion by the protrusion, so that the movable mold is formed at the protrusion. Wherein a seal is provided between the outer periphery of the front end portion and the inner periphery of the frame. 9. The injection molding method according to claim 7, wherein the projecting portion is formed by projecting a part of the frame in an inner circumferential direction of the frame. 10. A stepped portion is formed on the movable mold, and when the projecting portion undergoes stress deformation due to the pressure of the resin during the injection molding step, the stress of the projecting portion is generated at the stepped portion. The injection molding method according to any one of claims 7 to 9, wherein the deformation is restricted.