JP2019181494A - Forming method of caulking joint or negative angle structure body using composite laminate plate, and caulking joint and negative angle structure body - Google Patents

Abstract

To provide a forming method of a caulking joint or a negative angle structure body which has excellent adhesiveness and is capable of performing negative angle forming.SOLUTION: A forming method of caulking joint or negative angle structural body includes a process (a) of preparing a composite laminate plate which contains such a structure that a resin layer is sandwiched by metal layers via an adhesive layer having a melting point of 100 to 225°C, the resin layer having a melting point higher than the melting point described above, a ratio ηp/ηf of linear expansion coefficients ηf, ηp of the metal layer and the resin layer being 3 or more and the total plate thickness being 0.8 mm or more, a process (b) of performing a hemming processing or a press processing of assembling the composite laminate plate and an inner plate to provide a caulking joint, or a groove-shaped structure body or a hat-shaped structure body and a process (c) of performing heat treatment of the joint, or the groove-shaped structure body or the hat-shaped structure body at (melting point-20°C) or more of the adhesive layer and at a temperature less than melting point of the resin layer and reducing a bending angle of the joint, or the groove-shaped structure body or the hat-shaped structure body cooled to a temperature less than 100°C as compared to the bending angle before heat treatment.SELECTED DRAWING: Figure 15

Description

  The present disclosure relates to a method for forming a caulking joint or a negative angle structure using a composite laminate, and a caulking joint and a negative angle structure.

  In general, a steel plate is used as an outer plate of an automobile, and an aluminum plate is also used for the purpose of weight reduction (Patent Document 1).

  Moreover, in order to use a steel plate or an aluminum plate as an outer plate of an automobile, it is necessary to obtain a caulking joint with good adhesion (Patent Document 2).

JP 2008-101239 A JP 2005-28368 A

However, if the thickness of the steel plate or aluminum plate is reduced for weight reduction, the bending rigidity (tension rigidity) is lowered, and a high-class feeling cannot be obtained. The bending rigidity in the case of bending in the out-of-plane direction is expressed by the product of the elastic modulus of the material and the sectional second moment I of the shape. The elastic modulus is a value specific to the material, and the cross-sectional secondary moment I is expressed by the following formula:
I = b × ^t 3/12
(Where b is the width and t is the plate thickness)
And is proportional to the cube of the plate thickness.

  In addition, in order to obtain a caulking joint with good adhesion by hemming or to perform negative angle forming, there is a problem that a complicated process or a special mold is required, which increases the cost.

The gist of the present disclosure is as follows.
(1) A method for forming a caulking joint or a negative angle structure according to the present disclosure includes:
(A) including a structure in which a resin layer is sandwiched between metal layers via an adhesive layer;
The adhesive layer has a melting point of 100 ° C. or higher and 225 ° C. or lower,
The resin layer has a melting point higher than the melting point of the adhesive layer;
The ratio ηp / ηf of the linear expansion coefficient ηp of the resin layer to the linear expansion coefficient ηf of the metal layer is 3 or more,
Preparing a composite laminate having a total plate thickness of 0.8 mm or more;
(B) subjecting the composite laminate to hemming or pressing combined with an inner plate arranged in contact with the composite laminate to obtain a caulking joint, or a groove-shaped structure or a hat-shaped structure; and (C) The caulking joint or the negative angle structure is heat-treated at a temperature equal to or higher than the (melting point−20 ° C.) of the adhesive layer and lower than the melting point of the resin layer, and then cooled to less than 100 ° C. Or reducing the bending angle of the groove-shaped structure or the hat-shaped structure than before the heat treatment,
including.
(2) In the molding method according to (1), the bending angle reduction angle is 0.55 ° or more.
(3) In the molding method according to (1) or (2), a ratio of a total thickness of the resin layer included in the composite laminate to a total thickness of the metal layer included in the composite laminate is from 1.00. large.
(4) The composite laminate according to any one of (1) to (3) has a five-layer structure of metal layer / adhesive layer / resin layer / adhesive layer / metal layer.
(5) The caulking joint of the present disclosure includes an inner plate and a composite laminated plate that is hemmed and bent so as to be in close contact with the inner plate,
The composite laminate includes a structure in which a resin layer is sandwiched between metal layers via an adhesive layer,
The adhesive layer has a melting point of 100 ° C. or higher and 225 ° C. or lower,
The resin layer has a melting point higher than the melting point of the adhesive layer;
The ratio ηp / ηf of the linear expansion coefficient ηp of the resin layer to the linear expansion coefficient ηf of the metal layer is 3 or more,
The total thickness of the composite laminate is 0.8 mm or more.
(6) The negative angle structure of the present disclosure is composed of a composite laminate and has a groove-shaped or hat-shaped cross section,
The composite laminate includes a structure in which a resin layer is sandwiched between metal layers via an adhesive layer,
The adhesive layer has a melting point of 100 ° C. or higher and 225 ° C. or lower,
The resin layer has a melting point higher than the melting point of the adhesive layer;
The ratio ηp / ηf of the linear expansion coefficient ηp of the resin layer to the linear expansion coefficient ηf of the metal layer is 3 or more,
The total thickness of the composite laminate is 0.8 mm or more.

  According to the molding method of the present disclosure, it is possible to obtain a caulking joint or a negative angle structure with good adhesion without requiring a complicated process or a special mold.

FIG. 1 is a schematic cross-sectional view of a composite laminate having a five-layer structure. FIG. 2 is a schematic cross-sectional view when the inner plate is arranged and the composite laminated plate of the outer plate is hemmed. FIG. 3 is a schematic cross-sectional view of the hemmed composite laminate of FIG. 2 when heat-treated and cooled. FIG. 4 shows the cross-sectional shape, the cross-sectional secondary moment, the occupied area (volume) of the negative angle structure (B) obtained by using the conventional hat-shaped steels (A) and (C) and the composite laminate of the present disclosure. ), And a comparison of cross-sectional efficiency of member rigidity. FIG. 5 is a schematic cross-sectional view illustrating a method for evaluating bending rigidity. FIG. 6 is an appearance photograph of the hemmed composite laminate viewed from the side. FIG. 7 is an appearance photograph of the hemmed composite laminate viewed from the side. FIG. 8 is an appearance photograph of the hemmed metal plate viewed from the side. FIG. 9 is a schematic diagram for explaining hemming by press bending. FIG. 10 is a schematic diagram for explaining the hemming process by the roller hem. FIG. 11 is an external view photograph of the composite laminate after heat treatment and cooling to room temperature, as viewed from the side. FIG. 12 is an external view photograph of the composite laminate that has been heat-treated and cooled after the hemming process, as viewed from the side. FIG. 13 is an external view photograph of a composite laminate that has been heat-treated and cooled after hemming, as viewed from the side. FIG. 14 shows a simulation analysis model. FIG. 15 shows a simulation result. FIG. 16 shows a simulation result. FIG. 17 shows an analysis model inside the bend. FIG. 18 shows an analysis model on the outside of the bend. FIG. 19 is a contour diagram showing the amount of displacement obtained by analyzing heat shrinkage for the model of FIG. FIG. 20 is a contour diagram showing the amount of displacement obtained by analyzing thermal contraction for the model of FIG. FIG. 21 is a graph showing the closing angle of the in-bending R according to the ratio ηp / ηf of the linear expansion coefficient ηp of the resin layer to the linear expansion coefficient ηf of the metal layer. FIG. 22 is a graph showing the bending rigidity. FIG. 23 is a schematic diagram of a structure having a groove-shaped cross-sectional shape. FIG. 24 is a schematic diagram of a structure having a hat-shaped cross-sectional shape.

  The present disclosure includes (a) a structure in which a resin layer is sandwiched between metal layers via an adhesive layer, the adhesive layer has a melting point of 100 ° C. or higher and 225 ° C. or lower, and the resin layer is formed of the adhesive layer. A composite having a melting point higher than the melting point, a ratio ηp / ηf of the linear expansion coefficient ηp of the resin layer to a linear expansion coefficient ηf of the metal layer being 3 or more, and an overall plate thickness being 0.8 mm or more Preparing a laminated plate; (b) performing a hemming process or a pressing process in combination with an inner plate arranged in contact with the composite laminated plate on the composite laminated plate, and a caulking joint, or a grooved structure or a hat shape Obtaining a structure, and (c) heat-treating the caulking joint or groove-shaped structure or hat-shaped structure at a temperature not lower than the melting point of the adhesive layer and not higher than the melting point of the resin layer, and Cooling process below 100 ° C To, it includes reducing the caulking joint or the than before bending angle the heat treatment of the groove-shaped structure or a hat-shaped structure directed to a method of molding a caulking joint or negative angle structures.

  The composite laminate used in the molding method of the present disclosure includes a structure in which a resin layer is sandwiched between metal layers via an adhesive layer. The number of layers included in the composite laminate is not particularly limited, and the composite laminate can have a desired configuration as long as it includes a structure in which a resin layer is sandwiched between metal layers via an adhesive layer. For example, as shown in the schematic cross-sectional view of FIG. 1, the composite laminate 100 may have a five-layer structure of metal layer 10 / adhesive layer 30 / resin layer 20 / adhesive layer 30 / metal layer 10. It may have a structure in which at least one of a metal layer, an adhesive layer, and a resin layer is further added to a five-layer structure, or may further include a net-like wire rod layer formed in a net shape using a wire rod. For example, the composite laminate may have a seven-layer structure of metal layer / adhesive layer / network wire layer / resin layer / network wire layer / adhesion layer / metal layer. The composite laminate preferably has a five-layer structure of metal layer / adhesive layer / resin layer / adhesive layer / metal layer.

  In the forming method of the present disclosure, hemming or pressing is performed on the composite laminate to form a caulking joint or a negative angle structure, heat-treating the caulking joint or the negative angle structure at a predetermined temperature, and then a predetermined temperature. The cooling process is performed. As a result, the inner bending angle (hereinafter referred to as the bending angle) of the caulking joint formed by hemming or the negative angle structure formed by pressing can be further reduced, requiring complicated processes and special molds. In addition, it is possible to obtain a caulking joint with improved adhesion between the inner plate and the outer plate, or a negative angle structure.

  The total thickness of the composite laminate is 0.8 mm or more, preferably 1.0 mm or more, more preferably 1.2 mm or more, and further preferably 1.4 mm or more. When the composite laminate has a thickness in the above range, the bending rigidity can be ensured and the high-grade feeling of the outer plate can be enhanced.

  The total thickness of the metal layers included in the composite laminate is preferably 0.03 to 0.40 mm, more preferably 0.05 to 0.20 mm, and still more preferably 0.07 to 0.15 mm.

  The total thickness of the resin layers included in the composite laminate is preferably 0.06 to 0.80 mm, more preferably 0.10 to 0.50 mm, and still more preferably 0.14 to 0.30 mm.

  When the metal layer and the resin layer have a thickness in the above range, the composite laminate can be reduced in weight and bending rigidity.

  The ratio of the total thickness of the resin layers provided in the composite laminate / the total thickness of the metal layers provided in the composite laminate is preferably greater than 1.00 and not greater than 6.00, more preferably not less than 1.50 and not greater than 5.50. Preferably they are 1.75 or more and 5.00 or less, More preferably, they are 2.00 or more and 4.00 or less.

  When the metal layer and the resin layer have a ratio of the thickness of the resin layer / the thickness of the metal layer, the composite laminate can be further reduced in weight and bending rigidity, and has better adhesion. It is possible to obtain a caulking joint and to perform negative angle forming more easily.

  The adhesive layer is composed of an adhesive, and the adhesive has a melting point of 100 ° C. or higher and 225 ° C. or lower. The adhesive preferably has a melting point of 180 ° C. or lower, more preferably 170 ° C. or lower, and further preferably 160 ° C. or lower.

  The adhesive is preferably at least one of a thermocompression-bonded modified polypropylene adhesive, a thermoplastic resin adhesive, an elastomer adhesive, and an inorganic adhesive. The thermocompression modified polypropylene adhesive may have a melting point of about 160 ° C to 170 ° C.

  In the molding method of the present disclosure, the fluidity of the adhesive is increased by heat-treating the caulking joint or the negative angle structure at a temperature equal to or higher than the melting point of the adhesive layer and lower than the melting point of the resin layer, Stress generated between the metal layer and the resin layer during hemming or negative angle forming can be relaxed. In the subsequent cooling process, the bending angle formed by hemming or negative angle forming can be further closed without external force, so that a caulking joint having good adhesion can be obtained, or more easily A negative angle structure can be obtained.

  The lower limit of the heat treatment temperature is preferably equal to or higher than the melting point of the adhesive layer, more preferably higher than the melting point of the adhesive layer. The upper limit of the heat treatment temperature is preferably (melting point−20 ° C.) or less of the resin layer, more preferably (melting point−30 ° C.) or less of the resin layer. By heat-treating in the above temperature range, the above caulking joint or negative angle structure can be obtained more stably.

  The holding time within the above temperature range in the heat treatment step is preferably 0 (no holding) to 60 minutes, more preferably 5 to 30 minutes, and further preferably 10 to 20 minutes. The rate of temperature rise within the above temperature range in the heat treatment step is preferably 5 to 100 ° C./min, more preferably 10 to 50 ° C./min.

  The cooling treatment condition is not particularly limited as long as it is cooled to less than 100 ° C., but is preferably 70 ° C. or less, more preferably 50 ° C. or less, and further preferably to room temperature. The cooling rate is preferably 5 to 100 ° C./min, more preferably 10 to 50 ° C./min.

  In general, when manufacturing an automobile outer plate, the inner plate is disposed along the edge of the outer plate so as to be in contact with the outer plate, and hemming is performed on the outer plate so that the outer plate is in close contact with the inner plate disposed inside. Processing is carried out to form a caulking joint to bring the outer plate into close contact with the inner plate. Further, a baking coating process (BH process) is performed on the outer plate having the caulking joint at 100 to 225 ° C., particularly at 170 to 180 ° C. for 20 to 30 minutes. Therefore, when hemming is performed in the molding method of the present disclosure, preferably, BH treatment is performed as heat treatment. In other words, after the hemming process, the bending angle formed by the hemming process can be further closed by performing the BH treatment in which the adhesive layer is heated to (melting point−20 ° C.) or higher and lower than the melting point of the resin layer, and good adhesion is achieved. A caulking joint with can be obtained. Also in the case of performing press working or flanging in the molding method of the present disclosure, the same BH treatment is preferably performed as the heat treatment.

  The resin layer is made of resin. The resin of the resin layer has a melting point higher than the melting point of the adhesive of the adhesive layer, preferably a melting point of the adhesive of the adhesive layer + 20 ° C. or higher. The resin of the resin layer is preferably thermoplastic. The resin of the resin layer preferably has a melting point of more than 225 ° C., more preferably 250 ° C. or more, further preferably 270 ° C. or more, and even more preferably 290 ° C. or more. When the resin of the resin layer has a melting point in the above range, the resin layer can be prevented from melting in the heat treatment.

  The resin of the resin layer is preferably at least one of polyamide 6 (PA6), acetylcellulose, polybutylene terephthalate, polyamide 66 (PA66), polyethylene terephthalate, polyphenylene sulfide, and polyamideimide. Polyamide 6 (PA6) has a melting point of about 225 ° C, acetylcellulose has a melting point of about 230 ° C, polybutylene terephthalate has a melting point of about 245 ° C, polyamide 66 (PA66) has a melting point of about 265 ° C, and polyethylene terephthalate has a melting point of about 255 ° C. Melting point, polyphenylene sulfide may have a melting point of about 290 ° C, and polyamideimide may have a melting point of about 300 ° C.

  FIG. 2 is a schematic cross-sectional view when the inner plate 40 is arranged and the composite laminate 100 of the outer plate is hemmed. FIG. 3 shows a schematic cross-sectional view of the composite laminate 100 that has been hemmed in FIG. 2 when heat-treated at the predetermined temperature and then cooled to below 100 ° C. FIG. As shown in FIG. 2, since the springback occurs after the hemming process, the bending angle of the caulking joint of the composite laminate is opened, and the adhesion between the outer plate and the inner plate is lowered. According to the composite laminate of the present disclosure, by performing heat treatment and cooling treatment after hemming, as shown in FIG. 3, the bending angle of the caulking joint is closed, so that a caulking joint with high adhesion can be obtained. .

  The hemming process can be performed by a conventional method such as press bending or roller hem. The outer plate can be applied with a sealer to ensure adhesion after hemming.

  According to the forming method of the present disclosure, the composite laminate is pressed (press-bent) to form a groove-shaped structure or a hat-shaped structure, and then heat-treated at the predetermined temperature, and then cooled to less than 100 ° C. Since the bending angle can be closed by performing the step, negative angle forming can be easily performed. Negative angle molding refers to forming a molded part having a bending angle smaller than 90 °. A negative angle structure cannot be formed by a normal press method. In order to form a negative angle structure, a multi-step process or a cam method for moving a mold from an oblique direction is required, but the cost increases.

  The negative angle structure obtained by the molding method of the present disclosure can have a groove-shaped cross-sectional shape schematically shown in FIG. 23 or a hat-shaped cross-sectional shape schematically shown in FIG. The moment, the occupied area (volume), and the sectional efficiency of the member rigidity can be compatible.

  In FIG. 4, a hat-shaped steel (A) manufactured by a conventional method using a metal plate, and a hat-shaped steel having the same cross-sectional shape as the hat-shaped steel (A) using the forming method of the present disclosure are manufactured. The negative angle structure (B) produced by heat treatment at a temperature of 100 ° C. and then cooled to less than 100 ° C., and the flange portion having the same width as the negative angle structure (B) using a metal plate The cross-sectional shape of the hat-shaped steel (C) produced by the construction method, the cross-sectional secondary moment, the occupied area (volume), and the comparison of the cross-sectional efficiency of the member rigidity are shown.

  Regarding the sectional moment of inertia, the hat-shaped steel (A) having the largest cross-sectional area is excellent, but the negative angle structure (B) is also excellent because the wire length (distance from the center of the figure) is large, and the hat-shaped steel Steel (C) is inferior because of its small cross-sectional area.

  Regarding the occupied area (volume), the hat-shaped steel (A) having the largest cross-sectional area is inferior, and the negative-angle structure (B) and the hat-shaped steel (C) are excellent.

  Regarding the cross-sectional efficiency of the member rigidity, the hat-shaped steel (A) and the hat-shaped steel (C) are insufficient, but the negative angle structure (B) is excellent.

  Although not bound by theory, the reason why the bending angle is deformed in the closing direction by the heat treatment and the cooling treatment in the method of the present disclosure is considered as follows.

  Thermal distortion due to the difference in linear expansion coefficient between the metal layer and the resin layer is generated in the heat treatment process of the caulking joint or the groove-shaped structure or the hat-shaped structure obtained from the composite laminate. Here, when the heat treatment is performed by heating to a temperature higher than (melting point−20 ° C.) of the adhesive, the adhesive softens or melts, so that the adhesive force between the metal layer and the resin layer is reduced, and the metal layer Deviation occurs between the resin layer and the resin layer, and thermal strain due to the difference in linear expansion coefficient between the metal layer and the resin layer is alleviated. After the heat treatment, the metal layer and the resin layer are cured or re-adhered in the cooling process to less than 100 ° C., the metal layer and the resin layer shrink, and the difference between the linear expansion coefficient causes the metal layer and the resin layer to It is considered that a shear stress is generated during this period, and the bending angle is deformed in the closing direction.

  When the temperature is lower than 100 ° C., the metal layer and the resin layer are fixed, and when the heat treatment is performed at a temperature equal to or higher than the melting point (−20 ° C.) of the adhesive layer and lower than the melting point of the resin layer, the adhesive softens or melts. It is necessary to shift the interlayer between the resin layer and the resin layer.

  The metal layer is composed of a metal plate or an alloy plate having a melting point exceeding 225 ° C., and preferably a steel plate, an aluminum alloy plate, a copper alloy plate, a pure titanium plate, a titanium alloy plate, or a magnesium alloy plate. The steel plate preferably has a tensile strength of 270 to 590 MPa, and can be, for example, a plated steel plate, an electroplated steel plate, a tinplate, or a steel plate for cans (TFS: Tin Free Steel).

  The thickness of one layer of the adhesive layer is preferably 0.001 to 0.200 mm, more preferably 0.050 to 0.100 mm, and still more preferably 0.100 to 0.050 mm. When the adhesive layer has a thickness in the above range, the resin layer and the metal layer can be favorably bonded.

  When the outer plate is hemmed to form a caulking joint with the inner plate, the adhesion between the inner plate and the outer plate at the bent portion (flange portion) is important. The inner plate is not particularly limited, and can be a conventionally used metal plate or the like.

  According to the forming method of the present disclosure, after the hemming process or press process of the composite laminate, the bending angle can be reduced more than before the heat treatment by performing a heat treatment at the predetermined temperature and then performing a cooling process. The reduction angle (closing angle) of the bending angle with respect to the bending angle before the heat treatment is preferably 0.55 ° or more, more preferably 2.00 ° or more, further preferably 2.30 ° or more, and even more preferably 2.50. It is at least 0 °, more preferably at least 2.60 °, even more preferably at least 5.00 °, and even more preferably at least 5.10 °. Although the upper limit of the bending angle reduction angle is not particularly limited, it can be, for example, 20 ° or 10 °.

  The larger the ratio ηp / ηf of the linear expansion coefficient ηp of the resin layer to the linear expansion coefficient ηf of the metal layer, the larger the closing angle (change amount) of the bending angle in the cooling process after heat treatment, and the better the adhesion. A joint can be obtained, or a negative angle structure can be easily obtained.

  The ratio ηp / ηf of the linear expansion coefficient ηp of the resin layer to the linear expansion coefficient ηf of the metal layer is 3 or more, preferably 5 or more, more preferably 7 or more. When molding a caulking joint, the larger the ratio ηp / ηf, the larger the closing angle (change amount) of the bending angle in the cooling process after heat treatment, and it is possible to obtain a caulking joint with excellent adhesion, In the above range, it is possible to obtain an industrially required caulking force. Even in the case of forming a negative angle structure, the larger the ratio ηp / ηf, the larger the closing angle (change amount) of the bending angle in the cooling process after heat treatment, and no complicated process or special mold is required. In addition, a negative angle structure having a smaller bending angle can be easily obtained. A negative angle structure having a smaller bending angle has higher efficiency for obtaining a second moment of cross section and is more excellent in rigidity. The upper limit value of ηp / ηf is not particularly limited. For example, ηp / ηf may be 20 or less.

  When ηp / ηf is 3 in the case of 90 ° bending, the closing angle (change amount) of the bending angle becomes 0.55 ° by the heat treatment and the cooling treatment. In a part where the total ridge opening angle is 180 ° or more, the total closing angle is 1.1 °. Generally, the flange length required for forming a caulking joint between the inner plate and the outer plate by hemming is 25 mm, and the surface accuracy is ± 0.5 mm. That is, when the surface accuracy is low, a gap of 0.5 mm is generated, which may cause poor bonding. By setting ηp / ηf to 3 or more, the gap at the flange end can be narrowed by 0.5 mm (25 mm × sin (1.1 °) = 0.5 mm) and the gap can be closed.

For example, the coefficient of linear expansion of polyamide 6 (PA6), which is preferable as a material for the resin layer, is 5.9 to 10 × 10 ⁻⁵ / ° C., and the coefficient of linear expansion of acetylcellulose is 8 to 18 × 10 ⁻⁵ / ° C. The linear expansion coefficient of polybutylene terephthalate is 6.0 to 9.5 × 10 ⁻⁵ / ° C., and the linear expansion coefficient of polyamide 66 (PA66) is 8 to 10 × 10 ⁻⁵ / ° C. The linear expansion coefficient of polyethylene terephthalate is 6.5 × 10 ⁻⁵ / ° C., the linear expansion coefficient of polyphenylene sulfide is 4.9 × 10 ⁻⁵ / ° C., and the linear expansion coefficient of polyamideimide is 3.1 × 10 ⁻⁵ / ° C. For example, the linear expansion coefficient of a steel plate preferable as a material for the metal layer is 9.0 to 12.8 × 10 ⁻⁶ / ° C., and the linear expansion coefficient of an aluminum plate is 23 × 10 ⁻⁶ / ° C. The linear expansion coefficient is 17.7 × 10 ⁻⁶ / ° C. The material of the metal layer and the resin layer can be selected so that ηp / ηf has a desired ratio.

The composite laminate can be produced by sandwiching a resin between metal plates via an adhesive and hot pressing. Hot pressing is performed by, for example, pressing at a pressure of 0.01 to 5.00 MPa for 1.0 × 10 ^{1 to} 1.0 × 10 ⁵ seconds while heating the temperature to 100 to 200 ° C.

  The present disclosure is also a caulking joint including an inner plate and a composite laminated plate that is hemmed and bent so as to be in close contact with the inner plate, and the composite laminated plate sandwiches a resin layer with a metal layer via an adhesive layer. The adhesive layer has a melting point of 100 ° C. or higher and 225 ° C. or lower, the resin layer has a melting point higher than the melting point of the adhesive layer, and the linear expansion coefficient ηf of the metal layer A caulking joint in which the ratio ηp / ηf of the linear expansion coefficient ηp of the resin layer is 3 or more and the total thickness of the composite laminate is 0.8 mm or more is an object.

  The present disclosure is also a negative-angle structure that is formed of a composite laminate and has a groove-shaped or hat-shaped cross section, in which the composite laminate has a structure in which a resin layer is sandwiched between metal layers via an adhesive layer. The adhesive layer has a melting point of 100 ° C. or higher and 225 ° C. or lower, the resin layer has a melting point higher than the melting point of the adhesive layer, and the resin layer has a linear expansion coefficient ηf with respect to the linear expansion coefficient ηf. A negative angle structure in which the ratio ηp / ηf of the linear expansion coefficient ηp is 3 or more and the overall thickness of the composite laminate is 0.8 mm or more is intended.

  In the caulking joint and the negative angle structure according to the present disclosure, the configuration described for the molding method is applied to the configuration related to the composite laminate.

(Preparation of composite laminate)
A thermocompression-bonding-type modified polypropylene adhesive having a melting point of 160 ° C. is interposed between two steel plates for cans (TFS) each having a thickness of 0.2 mm and a linear expansion coefficient ηf of 11.7 × 10 ⁻⁶ / ° C. Sandwiching polyamide 6 (PA6) having a plate thickness of 0.54 mm, a melting point of 225 ° C., and a linear expansion coefficient ηp of 8 × 10 ⁻⁵ / ° C., 180 ° C. and 10000 kg, 1.0 × 10 ⁵ The film was hot-pressed for 2 seconds to produce a 5-layer composite laminate having a thickness of 1.1 mm. The vertical and horizontal dimensions of the composite laminate after press bonding were 400 mm × 600 mm. The ratio ηp / ηf of the linear expansion coefficient ηp of the polyamide 6 to the linear expansion coefficient ηf of the steel plate for cans was 6.8. The ratio of the total thickness of the resin layer to the total thickness of the metal layer was 1.35.

(Evaluation of bending stiffness)
About the produced composite laminated board, the bending rigidity was evaluated according to the method shown in FIG. In FIG. 5, the composite laminate 100 having dimensions of 1.1 mm × 30 mm × 200 mm is placed on R5.0 mm support points arranged at intervals of 100 mm, and the center portion is pushed by an R5.0 mm punch and bent. This represents a method for measuring the bending stiffness when molded. The bending rigidity was similarly evaluated about the aluminum plate and the steel plate for cans (TFS).

  As shown in FIG. 22, the composite laminate produced in Example 1 has a mass equivalent to that of a 0.50 mm thick steel plate for cans (TFS) and is significantly higher than the bending rigidity of a 0.50 mm thick steel plate for cans. Bending rigidity was obtained. This bending rigidity was equivalent to a 1.3 mm thick aluminum plate. Thus, the composite laminate produced in Example 1 exhibited light weight and high bending rigidity.

Example 1
0.54 mm between two tin plates each having a thickness of 0.2 mm and a linear expansion coefficient ηf of 11.7 × 10 ⁻⁶ / ° C. via a thermocompression-bonding type modified polypropylene adhesive having a melting point of 160 ° C. Is sandwiched between polyamide 6 (PA6) having a melting point of 225 ° C. and a melting point of 225 ° C. and a linear expansion coefficient ηf of 8 to 10 × 10 ⁻⁵ / ° C., 180 ° C. and 10,000 kg, and hot pressing for 1.0 × 10 ⁵ seconds. Thus, a 5-layer composite laminate having a thickness of 1.1 mm was produced. The vertical and horizontal dimensions of the composite laminate after press bonding were 400 mm × 600 mm. The ratio ηp / ηf of the linear expansion coefficient ηp of the polyamide 6 to the linear expansion coefficient ηf of the tin plate was 6.8.

  Hemming with an inner R bend radius of 1.0 mm without an inner plate was performed by press bending as shown in FIG. 9 to obtain a hemmed composite laminate as shown in FIG. As shown in FIG. 9, in the press bending, the bending at 180 degrees was completed in all two steps. Then, it was put into a drying furnace, heated in air to 170 ° C. at 0.1 ° C./second, heat-treated at 170 ° C. for 20 minutes, and then air-cooled to room temperature. By performing the heat treatment and the cooling treatment, the composite laminate was deformed in a direction in which the bending angle of the hemming portion was closed.

(Example 2)
A composite laminate was produced under the same conditions as in Example 1 except that the hemming was performed with the roller hem shown in FIG. 10, and the hemming with an inner R-bending radius of 1.0 mm was performed. A composite laminate was obtained. As shown in FIG. 10, in the roller hem, the 180-degree bending was completed in all four steps. Next, heat treatment and cooling treatment were performed in the same manner as in Example 1.

  In FIG. 11, the external appearance photograph which looked at the composite laminated sheet of Example 2 after the heat processing for 20 minutes at 170 degreeC and the cooling process to room temperature was seen from the side surface is shown. By performing the heat treatment and the cooling treatment, the composite laminate was deformed in a direction in which the bending angle of the hemming portion was closed.

(Example 3)
A composite laminate was prepared under the same conditions as in Example 2 except that heat treatment was performed at 170 ° C. for 5 minutes and then air-cooled to room temperature, hemming was performed, heat treatment and cooling treatment were performed, and the hemming shown in FIG. A processed composite laminate was obtained. By performing the heat treatment and the cooling treatment, the composite laminate was deformed in a direction in which the bending angle of the hemming portion was closed.

Example 4
After heating to 140 ° C., a composite laminate was produced under the same conditions as in Example 2 except that it was air-cooled to room temperature without maintaining the temperature, hemming was performed, heat treatment and cooling treatment were performed, and FIG. The hemmed composite laminate shown was obtained. By performing the heat treatment and the cooling treatment, the composite laminate was deformed in a direction in which the bending angle of the hemming portion was closed.

(Example 5)
A composite laminate was produced under the same conditions as in Example 1 except that a thermocompression-bonded modified polypropylene having a melting point of 170 ° C. was used as the adhesive, and hemming was performed with an inner R-bending radius of 1.0 mm. A laminate was obtained. Next, heat treatment and cooling treatment were performed under the same conditions as in Example 1.

(Example 6)
A composite laminate was produced under the same conditions as in Example 1 except that heat treatment was performed at 170 ° C. for 5 minutes, hemming was performed, and heat treatment and cooling treatment were performed.

(Comparative Example 1)
The 0.2 mm thick tin plate was hemmed under the same conditions as in Example 1 to obtain a hemmed metal plate shown in FIG.

  Table 1 shows the angle (change amount) at which the bending angle was closed after the heat treatment and the cooling treatment of the composite laminated plates of Examples 1 to 6 and the metal plate of Comparative Example 1 before heat treatment.

  Although the bending angle of the steel plate of Comparative Example 1 was substantially constant before and after the heat treatment and the cooling treatment, the bending angles of the composite laminates of Examples 1 to 6 were larger than those before the heat treatment by the heat treatment and the cooling treatment. Significantly smaller.

(Simulation analysis)
Simulation that assumes that the bending angle changes in the direction of closing in the heat treatment and room temperature cooling treatment, assuming that the adhesive melts in the heat treatment process and re-adhesion takes place between the metal layer and the resin layer in the cooling process. Analysis was performed.

  FIG. 14 shows an analysis model. A composite laminate having a length of 20 mm, in which a 0.7 mm thick resin layer is sandwiched between 0.2 mm thick (total 0.4 mm thick) steel plate layers, is joined at a corner having a bending angle of 90 ° and an inner bending radius R of 1 mm. I created a model. In the created model, the adhesive does not melt and keeps the joining of the steel plate layer and the resin layer, and the steel plate layer and the resin layer have a shared contact. For this model, the heat shrinkage strain upon cooling from 180 ° C. to 25 ° C. was calculated. Table 2 shows physical property values of the steel sheet layer and the resin layer.

  15 and 16 show the simulation results. As shown in FIG. 15, the bending angle decreased by 1.6 ° by cooling from 180 ° C. to 25 ° C. From the results of FIG. 16, it can be seen that when cooling, the bending angle decreases almost linearly.

  We further analyzed that the bending angle decreased during the cooling process, divided into the bending inner side and the bending outer side. FIG. 17 shows an analysis model inside the bend, and FIG. 18 shows an analysis model outside the bend.

  17 and 18, a composite laminate having a length of 4 mm in which a 0.7 mm-thick resin layer is sandwiched between 0.2 mm-thick steel plate layers is connected at a corner having a bending angle of 90 ° and an inner bending radius R of 1 mm. This is a model in the case where the object is cut in parallel with the joining surface of the steel plate layer and the resin layer at the center position in the thickness direction of the resin layer. That is, in each of FIGS. 17 and 18, the thickness of the resin layer is 0.35 mm.

  FIG. 19 shows the result of thermal shrinkage analysis performed on the model of FIG. FIG. 20 shows the result of thermal shrinkage analysis performed on the model shown in FIG. 19 and FIG. 20, it can be seen that the bending angle inside the bend is increased by the cooling process, and the bending angle outside the bend is decreased by the cooling process.

  From the analysis results of FIGS. 19 and 20, it is found that when the steel plate is placed outside the bend, the maximum value of the shear stress is 217 MPa, and when the steel plate is placed within the bend, the maximum value of the shear stress is 161 MPa. It was.

  From the above results, it is understood that the amount of displacement in the corner closing direction and the shear stress between the layers are larger when the steel plate is disposed outside the bend than when the steel plate is disposed within the bend. The boundary area between the steel sheet layer and the resin layer is larger when the steel sheet is disposed outside the bend than when the steel sheet is disposed within the bend. The larger the boundary area, the greater the shear stress and the more the bending direction of the bending angle dominates, so the bending angle of the composite laminate is considered to decrease with cooling.

The linear expansion coefficient ηf of the steel sheet layer is fixed to 11.7 × 10 ⁻⁶ (/ ° C.), and the linear expansion coefficient ηp of the resin layer is changed as shown in Table 3 and FIG. ηp / ηf was changed in the range of 1 to 11, and the closing angle of the in-bending R with respect to the linear expansion coefficient ratio ηp / ηf was examined.

  The larger the ratio ηp / ηf of the linear expansion coefficient ηp of the resin layer to the linear expansion coefficient ηf of the metal layer, the larger the closing angle (change amount) of the bending angle in the cooling process after heat treatment, and the better the adhesion. A joint can be obtained and a negative angle structure can be obtained easily. When ηp / ηf is 3 or more, the bending angle closing angle (change amount) by heat treatment and cooling treatment is 0.55 ° or more.

100 Composite Laminated Plate 10 Metal Layer 20 Resin Layer 30 Adhesive Layer 40 Inner Plate

Claims (6)

(A) including a structure in which a resin layer is sandwiched between metal layers via an adhesive layer;
The adhesive layer has a melting point of 100 ° C. or higher and 225 ° C. or lower,
The resin layer has a melting point higher than the melting point of the adhesive layer;
The ratio ηp / ηf of the linear expansion coefficient ηp of the resin layer to the linear expansion coefficient ηf of the metal layer is 3 or more,
Preparing a composite laminate having a total plate thickness of 0.8 mm or more;
(B) subjecting the composite laminate to hemming or pressing combined with an inner plate arranged in contact with the composite laminate to obtain a caulking joint, or a groove-shaped structure or a hat-shaped structure; and (C) heat-treating the caulking joint or the groove-shaped structure or the hat-shaped structure at a temperature equal to or higher than the melting point of the adhesive layer and less than the melting point of the resin layer; Reducing the bending angle of the caulking joint or the groove-shaped structure or the hat-shaped structure compared to before the heat treatment,
A method for forming a caulking joint or a negative angle structure.   The molding method according to claim 1, wherein a reduction angle of the bending angle is 0.55 ° or more.   The molding method according to claim 1 or 2, wherein a ratio of a total thickness of the resin layer included in the composite laminate to a total thickness of the metal layer included in the composite laminate is larger than 1.00.   The molding method according to claim 1, wherein the composite laminate has a five-layer structure of metal layer / adhesive layer / resin layer / adhesive layer / metal layer. A caulking joint including an inner plate and a composite laminate plate that is hemmed and bent so as to be in close contact with the inner plate;
The composite laminate includes a structure in which a resin layer is sandwiched between metal layers via an adhesive layer,
The adhesive layer has a melting point of 100 ° C. or higher and 225 ° C. or lower,
The resin layer has a melting point higher than the melting point of the adhesive layer;
The ratio ηp / ηf of the linear expansion coefficient ηp of the resin layer to the linear expansion coefficient ηf of the metal layer is 3 or more,
The total thickness of the composite laminate is 0.8 mm or more,
Caulking joint. A negative angle structure composed of a composite laminate and having a groove-shaped or hat-shaped cross-section,
The composite laminate includes a structure in which a resin layer is sandwiched between metal layers via an adhesive layer,
The adhesive layer has a melting point of 100 ° C. or higher and 225 ° C. or lower,
The resin layer has a melting point higher than the melting point of the adhesive layer;
The ratio ηp / ηf of the linear expansion coefficient ηp of the resin layer to the linear expansion coefficient ηf of the metal layer is 3 or more,
The total thickness of the composite laminate is 0.8 mm or more,
Negative angle structure.