Force-removed molded product

Abstract

To provide a force-removed product in which an occurrence of whitening and deformation is appropriately prevented and a deterioration of undercut is appropriately suppressed.SOLUTION: A force-removed molded product 1 includes a cylindrical body 2. The cylindrical body 2 has a cylindrical part 10 and a tip part 20. The tip part 20 has an undercut-shaped protrusion 23 that protrudes in an outer diameter direction, and a tapered part 24 that is provided so that an outer diameter becomes smaller from a top 25 of the protrusion 23 toward an end part 26 in a tip direction. A ratio of an inner diameter A of the tip part to an undercut height B of the protrusion 23 satisfies 0.030<B / A≤0.055, and an angle θ1 between a first line L1 and a second line satisfies 20°≤θ1<30°.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present disclosure relates to a forced demolding product.

Background Art

[0002] Conventionally, molding a resin composition by injection molding and forcibly demolding it from a mold is called forced demolding, and the molded product obtained thereby may be called a forced demolding product. For example, there is known a forced demolding product in which a resin composition is formed into a forced demolding product having a cylindrical portion, and the cylindrical portion has an undercut-shaped protrusion protruding in the outer diameter direction at the tip portion (see Patent Documents 1 and 2).

[0003] In conventional forced demolding products, when forcibly demolding from a mold, whitening, which is a sign of cracks, may occur on the inner wall surface, or the tip may be deformed. When the tip is deformed, the undercut height, which is the distance in the outer shape direction between the tangent line at the top of the protrusion and the outer wall surface of the cylindrical portion, decreases. For this reason, there has been a problem of affecting the quality of the forced demolding product.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] The present disclosure has been made in view of the above circumstances, and enables the provision of a forced demolding product in which the occurrence of whitening and deformation is appropriately prevented and the decrease in the undercut height is appropriately suppressed.

Means for Solving the Problems

[0006] To achieve the above object, the undercut molded product according to the present disclosure is an undercut molded product that is an injection molded body of a thermoplastic resin composition containing a thermoplastic resin and a fiber reinforcing material. The undercut molded product includes at least a hollow cylindrical cylinder. The cylinder has a cylindrical portion and a tip portion provided at one end of the cylindrical portion. The tip portion has an undercut-shaped protruding portion that protrudes in the outer diameter direction and a constriction portion provided so that the outer diameter decreases from the top of the protruding portion toward the end portion in the tip direction. When the inner diameter of the tip portion is A and the undercut height, which is the distance in the outer diameter direction between the tangent line at the top of the protruding portion and the outer wall of the cylindrical portion, is B, the ratio of A to B is 0.030 < B / A ≦0.055 is satisfied, and an angle θ1 between a first line that is a tangent line at the top of the protruding portion and parallel to the central axis of the cylindrical portion and a second line that connects the outer edge of the end portion and the top of the protruding portion is 20° ≦ θ1 <30° is satisfied.

Advantages of the Invention

[0007] According to the present disclosure, an undercut molded product in which the concentration of stress and strain on the tip portion is suppressed during mold release can be obtained. Therefore, it is possible to provide an undercut molded product in which the occurrence of whitening and deformation is appropriately prevented and the decrease in the undercut height is appropriately suppressed. As a result, it is possible to provide an undercut molded product with excellent quality.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Modes for Carrying Out the Invention

[0009] (First Embodiment) The forced demolding molded article 1 according to the first embodiment, which is one embodiment of the present disclosure, will be described as follows with reference to FIGS. 1 to 3. The forced demolding molded article 1 according to the present embodiment is an injection molded article of a thermoplastic resin composition containing a thermoplastic resin and a fiber reinforcing material.

[0010] As shown in FIGS. 1 to 3, the forced demolding molded article 1 of the present embodiment includes at least a hollow cylindrical cylinder 2. The forced demolding molded article 1 includes a molded body 3 having a desired shape in addition to this cylinder 2.

[0011] One end of the cylinder 2 is open and has an opening 2a, and the other end is connected to the molded body 3. The cylinder 2 has at least a cylindrical portion 10 and a tip portion 20. The cylindrical portion 10 has a hollow cylindrical shape. The cylindrical portion 10 has an outer wall 11 and an inner wall 12. The tip portion 20 is provided at one end of the cylindrical portion 10, and the molded body 3 is connected to the other end.

[0012] The tip portion 20 has an outer wall 21, an inner wall 22, a protruding portion 23, and a constriction portion 24. The protruding portion 23 has an undercut shape protruding in the outer diameter direction. As shown in FIGS. 2 and 3, the constriction portion 24 is provided such that the outer diameter decreases from the top 25 (vertex D) of the protruding portion 23 toward the end 26 in the tip direction. On the other hand, the inner diameters of the protruding portion 23 and the constriction portion 24 are substantially the same from the end 26 to the rear end toward the molded body 3.

[0013] As shown in Fig. 2, the inner diameter A of the tip portion 20 is formed larger than the inner diameter C of the cylindrical portion 10. The inner surface wall 22 of the tip portion 20 is provided via an inclined portion 30 such that the inner diameter increases from the inner surface wall 12 of the cylindrical portion 10 toward the tip portion 20. By providing such an inner surface wall 22, the concentration of stress on the tip portion 20 during mold release is suppressed. The inclined portion 30 has a plurality of annular inclined surfaces 31 (31a, 31b, 31c) with different inclination angles. For this reason, the inner surface wall 3z2 of the inclined portion 30 is stepped. The inclined portion 30 of the present embodiment has three inclined surfaces 31a, 31b, 31c, but is not limited thereto, and the number of inclined surfaces 31 may be two or less, or four or more.

[0014] As shown in Fig. 2, for the forced demolding product 1 of the present embodiment, when the inner diameter of the tip portion 20 is A and the undercut height, which is the outer diameter direction distance between the tangent line at the top 25 (vertex D) of the protruding portion 23 and the outer surface wall 11 of the cylindrical portion 10, is B, the ratio of A to B satisfies the following formula (1).

[0015] 0.030 < B / A ≦ 0.055 (1)

[0016] If the ratio of A to B is 0.030 or less, which is the lower limit value of the above formula (1), the undercut height becomes low, which is not preferable. On the other hand, if the ratio of A to B exceeds 0.055, which is the upper limit value of the above formula (1), the undercut height becomes high, and the stress and strain on the tip portion 20 during mold release become large, and whitening or deformation may occur, which is not preferable. By the ratio of A to B being within the range of the above formula (1), the concentration of stress and strain on the cylindrical body 2 is appropriately suppressed, the occurrence of whitening and deformation of the cylindrical body 2 is appropriately prevented, and the undercut height is maintained.

[0017] Furthermore, the desirable dimensions of the forced-draft molded product 1 of the present embodiment are described as follows with reference to FIG. 3. In the forced-draft molded product 1 of the present embodiment, the angle θ1 between a first line L1 that is a tangent at the top 25 of the protruding portion 23 and is parallel to the central axis O of the cylindrical portion 10, and a second line L2 that connects the outer edge 26a of the end portion 26 and the top 25 (apex D) of the protruding portion 23 satisfies the following formula (2). The top 25 is the portion with the largest outer diameter of the protruding portion 23 and is continuously annular. The apex D is any point on this annular top 25 and is represented as the upper end point of the cross-section of the top 25 in FIG. 3.

[0018] 20° ≦ θ1 <30° (2)

[0019] If the angle θ1 is less than 20°, which is the lower limit value of the above (2), the stress on the tip 20 during mold release increases and the inner wall 22 is damaged. If the angle θ1 exceeds 30°, which is the upper limit value of the above formula (2), the strain on the tip 20 during mold release increases and deformation occurs, which is not preferable. By having θ1 within the range of the above formula (2), the concentration of stress and strain on the cylindrical body 2 is appropriately suppressed, the whitening and deformation of the cylindrical body 2 are appropriately prevented, and the undercut height is maintained.

[0020] Also, in the forced-draft molded product 1 of the present embodiment, it is desirable that the angle θ2 between a first line L1 that is a tangent at the top 25 (apex D) of the protruding portion 23 and is parallel to the central axis O of the cylindrical portion 10, and a third line L3 that connects the top 25 (apex D) of the protruding portion 23 and the boundary portion 33 (boundary point F) between the outer wall 11 of the cylindrical portion 10 and the outer wall 21 of the tip portion 20 satisfies the following formula (3). The boundary point F is a point on the boundary portion 33 and is the point where the plane including the apex D and the central axis O intersects the boundary portion 33.

[0021] 10° ≦ θ2 < 25° (3)

[0022] If the angle θ2 is less than 10° which is the lower limit of the above (3), the stress on the tip 20 during mold release will increase and breakage will occur. If the angle θ2 is 25° or more which is the upper limit of the above formula (3), the distortion on the tip 20 during mold release will increase and deformation will occur. By having θ1 within the range of the above formula (2), the concentration of stress and distortion on the cylindrical body 2 is appropriately suppressed, the whitening and deformation of the cylindrical body 2 are appropriately prevented, and the undercut height is maintained.

[0023] Note that the forced demolding product 1 of the present disclosure only needs to satisfy at least the above formula (1), and it is more desirable to satisfy both the above formula (1) and the above formula (2). Further, it is even more desirable for the forced demolding product of the present disclosure to satisfy the above formula (1), the above formula (2), and the above formula (3).

[0024] Also, for the tip 20 of the forced demolding product 1 of the present embodiment, it is desirable that the thickness E at the end 26 is 0.5 mm or more and 1.0 mm or less. The thickness E at the end 26, in other words, the distance between the outer surface wall 21 and the inner surface wall 22 at the end 26. If the thickness E is less than 0.5 mm, the strength of the tip 20 will decrease, which is not preferable. If the thickness E exceeds 1.0 mm, the concentration of stress or distortion on the tip 20 during mold release will increase, which is not preferable. By having the thickness E at the end 26 within the above range, the forced demolding product 1 is excellent in strength, and the occurrence of whitening and deformation is more appropriately prevented, and the decrease in the undercut height is more appropriately suppressed.

[0025] Also, in the forced demolding product 1 of the present embodiment, it is desirable that the boundary portion 33 has a curved surface 34 with a curvature R of 2 or more and 10 or less. If the curvature R is less than 2, the stress on the boundary portion 33 during mold release will increase, which is not preferable. If the curvature R exceeds 10, the undercut height will decrease, which is not preferable. By having the curvature R of the boundary portion 33 within the above range, the forced demolding product 1 more appropriately prevents the occurrence of whitening and deformation, and more appropriately suppresses the decrease in the undercut height.

[0026] As described above, the forced demolding molded article 1 of the present embodiment is a thermoplastic resin composition containing a thermoplastic resin and a fiber reinforcing material. The manufacturing method of the forced demolding molded article 1 is not particularly limited, and it can be manufactured using a known manufacturing method. By manufacturing the forced demolding molded article 1 with dimensions and the like as described above during this manufacturing, the concentration of stress and strain on the cylindrical body 2 can be suppressed, and the occurrence of whitening and deformation can be appropriately prevented. Further, in the forced demolding molded article 1, the reduction of the undercut height is suppressed, and the undercut height is maintained.

[0027] The material of the forced demolding molded article 1 of the present embodiment is not particularly limited, and any thermoplastic resin composition containing a thermoplastic resin and a fiber reinforcing material may be used. Examples of the thermoplastic resin include polyamide resin, polyphenylene sulfide resin, polypropylene resin, polyethylene resin, polybutylene terephthalate resin, polyethylene terephthalate resin, polyester resin, acrylic resin, polyolefin resin, aramid resin, etc. Among these, polyamide resin is most preferably mentioned.

[0028] Examples of the polyamide resin include condensation polymers of dicarboxylic acid and diamine, ring-opening polymers of cyclic lactams, and condensation polymers of aminocarboxylic acids. Examples of the dicarboxylic acid include aliphatic dicarboxylic acids such as malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, undecanedioic acid, dodecanedioic acid, dimethylmalonic acid, 2,2 - diethylsuccinic acid, 2,2 - dimethylglutaric acid, 2 - methyladipic acid, and trimethyladipic acid; alicyclic dicarboxylic acids such as 1,3 - cyclopentanedicarboxylic acid, 1,3 - cyclohexanedicarboxylic acid, 1,4 - cyclohexanedicarboxylic acid, cycloheptanedicarboxylic acid, cyclooctanedicarboxylic acid, and cyclodecanedicarboxylic acid; and aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, phthalic acid, 2,6 - naphthalenedicarboxylic acid, 2,7 - naphthalenedicarboxylic acid, 1,4 - naphthalenedicarboxylic acid, 1,4 - phenylenedioxydiacetic acid, 1,3 - phenylenedioxydiacetic acid, diphenic acid, diphenylmethane - 4,4’ - dicarboxylic acid, diphenylsulfone - 4,4’ - dicarboxylic acid, and 4,4’ - biphenyldicarboxylic acid. These dicarboxylic acids can be used alone or in combination of two or more.

[0029] The polyamide resin may further contain, within a range not impairing the effects of the present disclosure, structural units derived from polyvalent carboxylic acids having a valence of 3 or more, such as trimellitic acid, trimesic acid, and pyromellitic acid, within a range where melt molding is possible.

[0030] Examples of the diamine include aliphatic diamines, alicyclic diamines, aromatic diamines, etc. Examples of the aliphatic diamine include linear aliphatic diamines such as ethylenediamine, 1,2-propanediamine, 1,3-propanediamine, 1,4-butanediamine, 1,5-pentanediamine, 1,6-hexanediamine, 1,7-heptanediamine, 1,8-octanediamine, 1,9-nonanediamine, 1,10-decanediamine, 1,11-undecanediamine, 1,12-dodecanediamine; branched aliphatic diamines such as 1-butyl-1,2-ethanediamine, 1,1-dimethyl-1,4-butanediamine, 1-ethyl-1,4-butanediamine, 1,2-dimethyl-1,4-butanediamine, 1,3-dimethyl-1,4-butanediamine, 1,4-dimethyl-1,4-butanediamine, 2,3-dimethyl-1,4-butanediamine, 2-methyl-1,5-pentanediamine, 3-methyl-1,5-pentanediamine, 2,5-dimethyl-1,6-hexanediamine, 2,4-dimethyl-1,6-hexanediamine, 3,3-dimethyl-1,6-hexanediamine, 2,2-dimethyl-1,6-hexanediamine, 2,2,4-trimethyl-1,6-hexanediamine, 2,4,4-trimethyl-1,6-hexanediamine, 2,4-diethyl-1,6-hexanediamine, 2,2-dimethyl-1,7-heptanediamine, 2,3-dimethyl-1,7-heptanediamine, 2,4-dimethyl-1,7-heptanediamine, 2,5-dimethyl-1,7-heptanediamine, 2-methyl-1,8-octanediamine, 3-methyl-1,8-octanediamine, 4-methyl-1,8-octanediamine, 1,3-dimethyl-1,8-octanediamine, 1,4-dimethyl-1,8-octanediamine, 2,4-dimethyl-1,8-octanediamine, 3,4-dimethyl-1,8-octanediamine, 4,5-dimethyl-1,8-octanediamine, 2,2-dimethyl-1,8-octanediamine, 3,3-dimethyl-1,8-octanediamine, 4,4-dimethyl-1,8-octanediamine, 5-methyl-1,9-nonanediamine, etc. Examples of the alicyclic diamine include cyclohexanediamine, methylcyclohexanediamine, isophoronediamine, norbornanedimethylamine, tricyclodecanedimethylamine, and the like. Examples of the aromatic diamine include p-phenylenediamine, m-phenylenediamine, p-xylylenediamine, m-xylylenediamine, 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylsulfone, 4,4'-diaminodiphenylether, and the like. These diamines can be used alone or in combination of two or more.

[0031] The polyamide resin may further contain a structural unit derived from a polyvalent amine having a valence of 3 or more, such as bis(hexamethylene)triamine, within a range not impairing the effects of the present disclosure and within a range where melt molding is possible.

[0032] Examples of the cyclic lactam include acetolactam, propiolactam, butyrolactam, valerolactam, caprolactam, enantholactam, caprylolactam, pelargolactam, caprinolactam, laurolactam, and the like. Examples of the aminocarboxylic acid include aminopropionic acid, aminobutyric acid, aminovaleric acid, aminocaproic acid, aminoenanthic acid, aminocaprylic acid, aminopelargonic acid, aminocapric acid, aminolauric acid, and the like.

[0033] The polyamide resin is preferably used as an aliphatic polyamide, wholly aromatic polyamide, or semi-aromatic polyamide by appropriately combining monomers such as the above dicarboxylic acid, diamine, cyclic lactam, aminocarboxylic acid, polyvalent carboxylic acid having a valence of 3 or more, and polyvalent amine having a valence of 3 or more. Examples of the aliphatic polyamide include ring-opening polymers of the above cyclic lactams, polycondensation products of the above aminocarboxylic acids, or polycondensation products of the above aliphatic dicarboxylic acids and the above aliphatic diamines. Among them, from the viewpoints of flame retardancy, heat resistance, and moldability in thin films, the polycondensation product of the above aliphatic dicarboxylic acid and the above aliphatic diamine is preferable, and polyamide 46 is more preferable from the viewpoint of ease of production. Examples of semi-aromatic polyamides include polytetramethylene terephthalamide (polyamide 4T), polyhexamethylene terephthalamide (polyamide 6T), polynonamethylene terephthalamide (polyamide 9T), polydecamethylene terephthalamide (polyamide 10T), polyhexamethylene isophthalamide (polyamide 6I), a copolymer of polyamide 6I and polyamide 6T (polyamide 6I / 6T), and a copolymer of polyamide 6T and polyundecanamide (polyamide 11). Among them, at least one selected from the group consisting of polyamide 4T, polyamide 6T, polyamide 9T, and polyamide 10T is preferable, at least one selected from the group consisting of polyamide 9T and polyamide 10T is more preferable, and polyamide 9T is even more preferable.

[0034] The fiber reinforcing material is not particularly limited. For example, glass fiber, carbon fiber, aramid fiber, boron fiber, polyethylene fiber, zylon fiber, etc. are preferably mentioned. Among these, glass fiber is most preferably mentioned.

[0035] It is considered that the following two deformation modes (deformation mode 1 and deformation mode 2) occur in the protruding part corresponding to the undercut when the undercut molded product is demolded. (a) Deformation mode 1: When the protruding part of the undercut molded product passes through the cylindrical part of the mold, the top of the protruding part is compressed in the inner diameter direction, and the inner surface of the protruding part is pulled. (b) Deformation mode 2: When the protruding part of the undercut molded product passes through the cylindrical part of the mold, the tip of the protruding part is deformed in the inner diameter direction, and the diameter of the tip part is reduced.

[0036] In the above deformation mode 1, a load corresponding to a bending load is applied to the protruding part, and stress concentration occurs on the inner surface of the protruding part. When a stress exceeding the yield strength of the thermoplastic resin is generated, whitening or cracking occurs in the undercut molded product. On the other hand, in deformation mode 2, a compressive strain occurs due to the reduction of the diameter of the tip part. When a strain exceeding the yield strength of the thermoplastic resin is generated, buckling occurs, and accordingly, the tip part is deformed.

[0037] These two deformation modes occur simultaneously but are considered to be in an antinomic relationship. It is considered that when one of the deformation modes appears prominently, the other deformation mode hardly appears.

[0038] Based on the above mechanism, as a result of intensive studies by the inventor, it was considered whether destruction and deformation could be suppressed by changing the shape of the protruding portion. As a result of this study, it was discovered that by adjusting the angle between the tangent at the top (apex) of the protruding portion and the line connecting the top (apex) of the protruding portion from the outer wall of the end portion of the tip portion, and the angle between the tangent at the top (apex) of the protruding portion and the line connecting the top (apex) of the protruding portion from the outer wall of the end portion, the bending rigidity of the protruding portion changes, and the deformation mode occurring during mold release changes. Specifically, it was discovered that when the bending rigidity of the protruding portion decreases, the tendency of deformation mode 1 becomes stronger, and when it increases, the tendency of deformation mode 2 becomes stronger. Therefore, the inventor found that by changing the shape of the protruding portion so that the stress and compressive strain caused by forced ejection satisfy the yield strength of the thermoplastic resin, it is possible to create a forced ejection molded product without destruction and deformation, and thus completed the present disclosure.

[0039] That is, the forced ejection molded product 1 according to the first embodiment, which is an embodiment of the present disclosure, is a forced ejection molded product that is an injection molded body of a thermoplastic resin composition containing a thermoplastic resin and a fiber reinforcing material. The forced ejection molded product 1 includes at least a hollow cylindrical cylinder 2. The cylinder 2 has a cylindrical portion 10 and a tip portion 20 provided at one end of the cylindrical portion 10. The tip portion 20 has an undercut-shaped protruding portion 23 that protrudes in the outer diameter direction, and a tapered portion 24 provided so that the outer diameter decreases from the top 25 of the protruding portion 23 toward the end portion 26 in the tip direction.

[0040] Then, for the undercut-free molded product 1 according to the first embodiment, when the inner diameter of the tip portion 20 is A and the undercut height, which is the distance in the outer diameter direction between the tangent line at the top portion 25 of the protruding portion 23 and the outer surface wall 11 of the cylindrical portion 10, is B, the ratio of A to B satisfies the above-mentioned formula (1), and the angle θ1 between the first line L1, which is the tangent line at the top portion 25 of the protruding portion 23 and is parallel to the central axis O of the cylindrical portion 10, and the second line L2 connecting the outer edge 26a of the end portion 26 and the top portion 25 of the protruding portion 23 satisfies the above-mentioned formula (2).

[0041] By having the above configuration, the undercut-free molded product 1 according to the first embodiment can suppress the concentration of stress and strain on the tip portion 20 during demolding. Therefore, in the undercut-free molded product 1 of the first embodiment, the occurrence of whitening and deformation is appropriately prevented, and the reduction of the undercut height is appropriately suppressed. As a result, the undercut-free molded product 1 has excellent quality.

Examples

[0042] Specific Examples 1 to 4 and Comparative Examples 1 to 4 of the undercut-free molded product 1 of the present disclosure will be described as follows with reference to Table 1 described later. This Table 1 is a table showing various dimensions and evaluation results of the undercut-free molded product 1 of each example and the undercut-free molded product 1 of each comparative example.

[0043] [Evaluation Method] The evaluation of the maximum principal stress, equivalent strain, and appearance of each example and each comparative example was performed as follows. The evaluation results are as shown in Table 1.

[0044] [Analysis Simulation] 3D models of the undercut-free molded products 1 of each example and each comparative example having the shapes shown in Table 1 were created and executed by computer simulation using the data of the following thermoplastic resin composition. First, a flow analysis was performed using "Moldflow 2021" manufactured by Autodesk, Inc., which is a resin flow analysis simulation, to obtain the fiber orientation. Next, using the previously obtained analysis results of fiber orientation, the material properties of the stretch-formed part according to the fiber orientation were defined using "Digimat 2022.1" manufactured by MSC Software Corporation. Then, using "ANSYS Mechanical 2021R2" manufactured by ANSYS, which is a structural analysis simulation, the mold release process of the stretch-formed part was simulated, and the maximum principal stress (equivalent to tensile stress) generated and the equivalent strain generated at the tip of the protrusion were evaluated. The obtained maximum principal stress and equivalent strain are shown in Table 1, respectively. The options of the analysis software were set as follows. · Analysis shape: Cylindrical part with different shapes of the stretch-formed part · Temperature condition: 150 °C · Contact condition: The contact surface (side) between the cylindrical body and the mold slides with a friction coefficient of 0.1, with contact with friction · Constraint condition: The bottom flange surface of the cylindrical body is fixed and constrained in three axes · Load condition: The mold is forced to displace axially until the protrusion comes out · Calculation condition: Large deformation mode · Mesh condition: Quadrilateral or triangular quadratic mesh is used, and the mesh size is 0.5

[0045] (1) Maximum principal stress Regarding the stretch-formed part 1 of each example and each comparative example, when the maximum value of the principal stress (maximum principal stress) generated in the inner diameter part of the protrusion 23 obtained by the analysis simulation exceeds the specified value (53 MPa), it was evaluated that fracture occurs. The evaluation results of the maximum principal stress in Table 1 are based on the following evaluation criteria. A: Since it is below the specified value, no fracture occurs. B: Since it exceeds the specified value, fracture occurs.

[0046] (2) Equivalent strain When the maximum value of the equivalent strain generated at the tip of the protrusion 23 obtained by the analysis simulation exceeds the compressive yield strain (0.21), it was evaluated that fracture occurs. The evaluation results of the equivalent strain in Table 1 are based on the following evaluation criteria. A: Since it is below the specified value, no deformation occurs. B: Since it exceeds the specified value, deformation occurs.

[0047] (3) Appearance evaluation: Whitening The whitening in the appearance of the forced demolding products 1 of Example 1 and Comparative Example 1 molded by the above manufacturing method was evaluated. The evaluation results of whitening in Table 1 are based on the following evaluation criteria. A: No whitening was confirmed. B: Whitening was confirmed.

[0048] (4) Appearance evaluation: Deformation The deformation in the appearance of the forced demolding products 1 of Example 1 and Comparative Example 1 molded by the above manufacturing method was evaluated. The evaluation results of deformation in Table 1 are based on the following evaluation criteria. A: There is no deformation at the tip of the protruding part including the opening of the cylindrical body. B: Deformation was confirmed at the tip of the protruding part including the opening of the cylindrical body.

[0049] The forced demolding products 1 of Example 1 and Comparative Example 1 were produced by the following materials and manufacturing methods. The inner diameter A (mm), undercut height B (mm), ratio of B / A, angle θ1 (°), angle θ2 (°), and thickness E (mm) of the tip part 20 of the forced demolding products 1 of Example 1 and Comparative Example 1 are as shown in Table 1.

[0050] [Materials] A thermoplastic resin composition containing polyamide resin (PA9T; 65 parts by mass) and glass fiber (35 parts by mass) was prepared as the thermoplastic resin.

[0051] [Manufacturing method] The above thermoplastic resin composition was supplied from a hopper to a SE100 injection molding machine manufactured by Toshiba Machine Co., Ltd. (set cylinder temperature: 320 °C). Further, a mold having a cylindrical shape with a protruding part at the tip and an undercut shape was installed in this injection molding machine, and injection molding was performed. The mold temperature was set to 140 °C recommended for the material. The forced demolding products 1 of Example 1 and Comparative Example 1 having the dimensions shown in Table 1 were produced.

[0052] Incidentally, the forced demolding products 1 of Examples 1 to 4 are specific examples of the forced demolding product 1 of the first embodiment shown in FIGS. 1 to 3.

[0053]

Table 1

[0054] From the results in Table 1, in the forced demolding products 1 of Examples 1 to 4, fracture did not occur because the maximum principal stress in the analysis was below the specified value, deformation did not occur because the generated strain was below the specified value, and whitening and deformation were not confirmed in terms of appearance. Therefore, it was found that the forced demolding products 1 of Examples 1 to 4 appropriately prevented the occurrence of whitening and deformation, and appropriately suppressed the decrease in the undercut height.

[0055] On the other hand, for the forced demolding product of Comparative Example 1 where B / A exceeded the upper limit value of 0.055, fracture occurred because the maximum principal stress in the analysis exceeded the specified value, deformation occurred because the equivalent strain exceeded the specified value, and whitening and deformation occurred in terms of appearance. For Comparative Example 2 where the angle θ1 was less than 20° and the curvature R was less than 2, and Comparative Example 3 where the angle θ1 was less than 20°, fracture occurred because the maximum principal stress exceeded the specified value. For Comparative Example 4 where the angle θ1 was 30° or more, the thickness E exceeded 1.0 mm, and the curvature R was less than 2, deformation occurred because the equivalent strain exceeded the specified value.

[0056] As described above, the first embodiment of the present disclosure and Examples 1 to 4 have been described in detail with reference to the drawings. However, each of the above embodiments and examples is merely an illustration of the present disclosure. The present disclosure is not limited only to the configurations of the above embodiments and examples. Of course, design changes and the like within the scope that do not depart from the gist of the present disclosure are also included in the present disclosure.

[0057] Incidentally, regarding the description of each of the above embodiments and examples, the following is further disclosed. (1) A forced demolding product that is an injection molded product of a thermoplastic resin composition containing a thermoplastic resin and a fiber reinforcing material, The forced-drawing molded product includes at least a hollow cylindrical body. The cylindrical body has a cylindrical portion and a tip portion provided at one end of the cylindrical portion. The tip portion has an undercut-shaped protrusion protruding in the outer diameter direction and a tapered portion provided so that the outer diameter decreases from the top of the protrusion toward the end in the tip direction. When the inner diameter of the tip portion is A and the undercut height, which is the distance in the outer diameter direction between the tangent line at the top of the protrusion and the outer wall of the cylindrical portion, is B, the ratio of A to B is 0.030 < B / A ≦0.055 and An angle θ1 between a first line that is a tangent line at the top of the protrusion and parallel to the central axis of the cylindrical portion and a second line connecting the outer edge of the end portion and the top of the protrusion is 20° ≦ θ1 <30° A forced-drawing molded product that satisfies the above conditions. (2) The thickness of the tip portion at the end portion is 0.5 mm or more and 1.0 mm or less. The forced-drawing molded product according to (1) above. (3) An angle θ2 between the first line and a third line connecting the top of the protrusion and the boundary between the outer wall of the cylindrical portion and the outer wall of the tip portion is 10° ≦ θ2 < 25° satisfies The forced-drawing molded product according to (1) or (2) above. (4) The boundary between the top of the protrusion and the outer wall of the cylindrical portion and the outer wall of the tip portion has a curved surface with a curvature of 2 or more and 10 or less. The forced-drawing molded product according to any one of (1) to (3) above. (5) The inner diameter of the tip portion is larger than the inner diameter of the cylindrical portion, and an inclined portion is provided between the inner wall of the tip portion and the inner wall of the cylindrical portion so that the inner diameter decreases from the tip portion toward the cylindrical portion. The forced-drawing molded product according to any one of (1) to (4) above. (6) The inclined portion has a plurality of inclined surfaces with different inclination angles. The forced-drawing molded product according to (5) above.

Explanation of Signs

[0058] 1: Forced-drawing molded product 2: Cylindrical body 10: Cylindrical part 11: Outer wall 12: Inner wall 20: Tip part 21: Outer wall 22: Inner wall 23: Protrusion 24: Throttling part 25: Top part 26: End part 26a: Outer edge 30: Inclined part 31: Inclined surface 32: Inner wall 33: Boundary part 34: Curved surface

Claims

1. A forced ejection molded product which is an injection molded product of a thermoplastic resin composition containing a thermoplastic resin and a fiber reinforcing material, wherein the forced ejection molded product includes at least a hollow cylindrical cylinder, the cylinder has a cylindrical portion and a tip portion provided at one end of the cylindrical portion, the tip portion has an undercut-shaped protrusion protruding in the outer diameter direction and a tapered portion provided so that the outer diameter decreases from the top of the protrusion toward the end in the tip direction, when the inner diameter of the tip portion is A and the undercut height, which is the distance in the outer diameter direction between the tangent line at the top of the protrusion and the outer wall of the cylindrical portion, is B, the ratio of A to B is 0.030 < B / A ≤ 0.055 and the angle θ1 between a first line that is the tangent line at the top of the protrusion and parallel to the central axis of the cylindrical portion and a second line that connects the outer edge of the end portion and the top of the protrusion satisfies 20° ≤ θ1 < 30° A forced ejection molded product satisfying the above conditions.

2. The thickness of the tip portion at the end portion is 0.5 mm or more and 1.0 mm or less, The forced ejection molded product according to Claim 1.

3. The angle θ2 between the first line and a third line that connects the top of the protrusion and the boundary between the outer wall of the cylindrical portion and the outer wall of the tip portion satisfies the following formula 10° ≤ θ2 < 25° and The forced ejection molded product according to Claim 1 or 2.

4. The boundary between the top of the protrusion and the outer wall of the cylindrical portion and the outer wall of the tip portion has a curved surface with a curvature of 2 or more and 10 or less, The forced ejection molded product according to any one of Claims 1 to 3.

5. The inner diameter of the tip portion is larger than the inner diameter of the cylindrical portion, and an inclined portion is provided between the inner wall of the tip portion and the inner wall of the cylindrical portion so that the inner diameter decreases from the tip portion toward the cylindrical portion, The forced ejection molded product according to any one of Claims 1 to 4.

6. The inclined portion has a plurality of inclined surfaces with different inclination angles, The forced ejection molded product according to Claim 5.

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