Method and apparatus for molding metal laminate film

Abstract

A punch (2) and a pad (5) are opposed to each other such that a molded portion (3a) of a metal laminate film (3) to be processed is interposed between the punch (2) and the pad (5). An enclosed space (6, 7) is compressed to raise only the temperature of the molded portion (3a) while keeping the vicinity of the molded portion (3a) at a low temperature (S1, S2). After that, the enclosed space (6, 7) is moved with respect to the molded portion (3a) to perform first molding (S3) on the molded portion (3a), and then gas in the enclosed space (6) is released to perform second molding (S4) on the molded portion (3a) by means of the punch (2) and the pad (5).

Claims

1. A method for molding a metal laminate film, comprising the steps of: raising a temperature of a molded portion of the metal laminate film to be processed, by moving a punch of a cope to a pad inside a die of a drag to compress gas in a first enclosed space defined by the punch, an inner surface of a plate provided around the punch and the molded portion with an area, of the metal laminate film, surrounding the molded portion interposed between the plate and the die; first molding including primary molding on the molded portion, the primary molding including the step of moving the punch to the pad to press the gas in the first enclosed space while partially pressing the pad, which has been pressed upward close to the punch by a spring, by means of an end of a pin to move the pad against an urging force of the spring, the pin being connected to the cope at a proximal end of the pin, the primary molding being completed when the pad reaching a molding depth is stopped at a bottom dead center by an action of a cam mechanism; and second molding performed on the molded portion by further moving the punch to the pad while releasing the gas from the first enclosed space to mold the molded portion by means of the punch, the die, and the pad.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a cross-sectional view illustrating a molding apparatus according to a first embodiment, the molding apparatus being used for a method for molding a metal laminate film according to the present invention;

(2) FIG. 2 is a molding process drawing of the molding apparatus according to the first embodiment;

(3) FIG. 3 is a change chart showing a pressure, a temperature, and so on of each part in the steps of the first embodiment;

(4) FIG. 4 is a cross-sectional view illustrating a molding apparatus according to a second embodiment, the molding apparatus being used for a method for molding a metal laminate film according to the present invention;

(5) FIG. 5(a) is a plan view illustrating the cope of the molding apparatus used for the second embodiment;

(6) FIG. 5(b) is a plan view illustrating the drag of the molding apparatus used for the second embodiment;

(7) FIG. 6 is a molding process drawing of the molding apparatus according to the second embodiment;

(8) FIG. 7 is a change chart showing a pressure, a temperature, and so on of each part in the steps of the second embodiment;

(9) FIG. 8 is a cross-sectional view illustrating a molding apparatus according to a third embodiment, the molding apparatus being used for a method for molding a metal laminate film according to the present invention;

(10) FIG. 9(a) is a plan view illustrating the cope of the molding apparatus used for the third embodiment;

(11) FIG. 9(b) is a plan view illustrating the drag of the molding apparatus used for the third embodiment;

(12) FIG. 10 is a molding process drawing of the molding apparatus according to the third embodiment;

(13) FIG. 11 is a change chart showing a pressure, a temperature, and so on of each part in the steps of the third embodiment;

(14) FIG. 12(a) is a cross-sectional view illustrating an assembly of a cope and a drag according to a conventional technique;

(15) FIG. 12(b) is a cross-sectional view illustrating a metal laminate film pressed to a molded portion by a punch;

(16) FIG. 13(a) is a plan view of the cope taken along line A1-A1 of the conventional technique; and

(17) FIG. 13(b) is a plan view of the drag taken along line A2-A2 of the conventional technique.

DESCRIPTION OF THE EMBODIMENTS

(18) A method for molding a metal laminate film according to the present invention will be described below according to specific embodiments.

First Embodiment

(19) FIGS. 1 to 3 show a first embodiment of the present invention.

(20) As illustrated in FIG. 1, in an apparatus for molding a metal laminate film, a drag Do includes a die 1 and a pad 5 provided on a die hole 1a. A cope Up includes a punch 2 that is opposed to the die 1 with a certain clearance so as to sandwich a metal laminate film (hereinafter, will be referred to as a film) 3 between the punch 2 and the die 1, and a plate 4 that is attached around the punch 2. The punch 2 has a first hole 8 that releases air into the atmosphere. The first hole 8 is opened or closed by, for example, a valve 17 to control a flow of air. An operation control unit 30 controls the operations of the drag Do, the cope Up, the punch 2, the pad 5, and so on.

(21) The film 3 is a molded laminate of a centered metal thin film (containing aluminum, copper, iron, and so on) and resin layers (containing polyamide, polypropylene, PET, and so on) provided on two surfaces of the metal thin film.

(22) A first enclosed space 6 surrounded by the punch 2, the plate 4, and the film 3 is formed on a molded portion 3a. A second enclosed space 7 surrounded by the die 1, the pad 5, and the film 3 is formed under the molded portion 3a.

(23) Steps S1 to S5 illustrate a molding process performed by the operation control unit 30. FIG. 3 shows time variations in the shaping rate, pressure, and temperature of a molded article in each step. A shaping rate F of the molded article is defined as the total of migrations of material atoms/the total of migrations at the completion of the molded article. The initial shape is defined as 0% and the completion of the molded article is defined as 100%.

(24) In the graphs of FIGS. 3(a) to 3(g), t1 to t5 on the horizontal axes represent the following times: t1: the completion of enclosed space formation in step S1 of FIG. 2; t2: the completion of temperature rise in step S2; t3: the completion of first molding in step S3; t4: the completion of second molding in step S4; t5: the completion of return in step S5. The vertical axes in FIGS. 3(a) to 3(g) represent the following: Pu: a pressure in the first enclosed space 6; Pl: a pressure in the second enclosed space 7; Tm: the mean temperature of the molded portion 3a; Tu: a temperature in the first enclosed space 6; Tl: a temperature in the second enclosed space 7 Tp: temperatures on the punch 2, the die 1, the pad 5, and the plate 4.

(25) In the operations of the present embodiment, the temperature of the film 3 or the temperature of air in the first and second enclosed spaces 6 and 7 is increased, and then the film 3 and the spaces 6 and 7 are cooled. In the case where one of the resin layers on two surfaces of the film 3 has a higher melting temperature Ta, the other resin layer has a lower melting temperature Tb, and an outside air temperature is T0 (Ta>Tb>T0), a temperature Ts on the film 3 or in the air of the first and second enclosed spaces 6 and 7 is defined as an elevated temperature state when Ts satisfies Ta>Ts>Tb, whereas Ts=T0 is defined as a cooled state.

(26) First, in the enclosed space formation of step S1, the first enclosed space 6 surrounded by the punch 2, the plate 4, and the film 3 is formed on the molded portion 3a while the second enclosed space 7 surrounded by the die 1, the pad 5, and the film 3 is formed under the molded portion 3a. At this point, the film 3 is pressed by the plate 4 and the die 1 with a certain pressure. In this step, the shaping rate F is 0%, Pu=Pl=P0 (atmospheric pressure) is satisfied, and Tm=Tu=Tl=Tp=T0 (room temperature) is satisfied. The film 3 in the molded portion 3a is cooled.

(27) In the temperature rise of step S2, the punch 2 moves down along an arrow 2a and the pad 5b moves up to compress air in the first and second enclosed spaces 6 and 7, placing the molded portion 3a into an elevated temperature state 3e. In the case where one of the resin layers on the two surfaces of the film 3 has the higher melting temperature Ta and the other resin layer has the lower melting temperature Tb, the temperatures Tu and Tl of the first and second enclosed spaces 6 and 7 are set as Tu=Tl=T2 and Ta>T2>Tb. Thus, the mean temperature Tm of the molded portion 3a also rises to T2.

(28) In the first molding of step S3, the punch 2 moves down along the arrow 2a to increase an air pressure in the first enclosed space 6; meanwhile, the operation of the pad 5 is stopped to make a pressure difference from the second enclosed space 7, completing primary molding to a preformed shape. The pressure Pu in the first enclosed space 6, the pressure Pl in the second enclosed space 7 (Pu>Pl), and a pressure difference Pa required for the primary molding are set to satisfy (PuPl)>Pa. In this step, the shaping rate F is about 20% to 90%.

(29) In the second molding of step S4, the punch 2 further moves down along the arrow 2a to punch the film 3 by means of the punch 2, the die 1, and the pad 5. At this point, as shown in FIG. 3(g), the punch 2, the die 1, and the pad 5 are kept cooled (temperature T0). Thus, the film 3 raised at the temperature T2 (Ta>T2>Tb) at time t3 comes into contact with the punch 2, the die 1, and the pad 5 having low temperatures at time t4, so that the film 3 is cooled to the temperature T0.

(30) When the punch 2 reaches the bottom dead center, the valve 17 is opened to pass high temperature and high pressure air in the first enclosed space 6 to the outside of the first enclosed space 6 (along an arrow 11) through the first hole 8. The cooling period of the film 3 is shortened by opening the valve 17.

(31) Finally, in the return of step S5, the punch 2 is moved up along an arrow 2b with the opened valve 17 to the point of origin while releasing the air of the first enclosed space 6.

(32) These steps can suppress breaks on the molded article.

(33) Specifically, in step S2, only the molded portion 3a is locally placed into the elevated temperature state 3e, increasing the extensibility of the material of the molded portion 3a.

(34) Furthermore, in the first molding of step S3, the molded portion 3a sandwiched by the punch 2 and the pad 5 undergoes the primary molding into the preformed shape so as to extend the overall material before second molding. Thus, the material in the molded portion 3a can be evenly extended.

(35) In the punching of step S4, the molded portion 3a is kept in the elevated temperature state 3e for a short time after the punch 2 comes into contact with the film 3, causing high friction resistance between the punch 2 and the film 3. The friction force can accelerate a flow of material into the molded portion from the vicinity of the molded portion. Additionally, an area other than the molded portion 3a can be kept cooled between the die 1 and the plate 4 so as to have a smaller friction force, thereby accelerating a flow of material into the molded portion 3a.

(36) Moreover, in step S4, the film 3 raised in temperature is cooled again in contact with the punch 2 after punching, the molecular structures of the resin layers on the surfaces of the film 3 are fixed so as to stabilize plastic deformation and reduce the spring back of the material, thereby suppressing wrinkles in the molded portion 3a.

(37) Furthermore, in the present embodiment, the punch 2 directly comes into contact with the film 3 in the molded portion 3a to cool the film 3, thereby shortening a cooling time and a molding cycle.

(38) Moreover, the film 3 raised in temperature can be cooled at the completion of the molded shape, thereby preventing a change of the molded shape and reducing variations in shape.

Second Embodiment

(39) FIGS. 4 to 7 illustrate a second embodiment according to the present invention.

(40) The same configurations as in the first embodiment will be indicated by the same reference numerals.

(41) FIG. 4 is a cross-sectional view illustrating an apparatus for molding a metal laminate film. In FIG. 4, a cope Up and a drag Do in FIGS. 5(a) and 5(b) are cut along line A3-A3.

(42) The drag Do includes a die 1 and a pad 5 provided in a die hole 1a. The die 1 includes a second hole 9 that is set at a molding depth from the top surface of the die 1 such that the die hole 1a communicates with the outside.

(43) The cope Up includes a punch 2 that is opposed to the die 1 with a certain clearance so as to sandwich a film 3 between the punch 2 and the die 1, and a plate 4 that is attached around the punch 2. The punch 2 has a first hole 8 that releases air into the atmosphere. The first hole 8 is opened or closed by, for example, a valve 17 to control a flow of air.

(44) In this configuration, the punch 2 moves down to mold the film 3, which has a thickness of 50 m to 500 m on the die 1, into a predetermined molded shape. Resin layers on two surfaces of the film 3 may vary in thickness depending on the product application. The total thickness of the resin layers is 5% to 80% of the overall thickness. The molded shape, that is, the shape of the punch 2 ranges from about 5 mm5 mm to 400 mm400 mm. The molding depth ranges from 0.5 mm to 30 mm.

(45) The end of the punch 2 has a tapered portion 10 that is set by dividing the clearance between the die 1 and the punch 2 by the molding depth. The molded shape of a product and the surface of the punch 2 match with each other. An operation control unit 30 controls the operations of the drag Do, the cope Up, the punch 2, the pad 5, and so on.

(46) Steps S1, S2, S3-1, S3-2, S4-1, S4-2, S4-3, and S5 in FIG. 6 show a molding process performed by the operation control unit 30 according to the second embodiment.

(47) FIGS. 7(a) to 7(g) show time variations in the shaping rate, pressure, and temperature of a molded article according to the present embodiment. Marks in FIGS. 7(a) to 7(g) are identical to those of FIG. 3 of the first embodiment.

(48) FIGS. 7(a) to 7(g) show the following times: time t1: the completion of enclosed space formation in step S1 of FIG. 6 time t2: the completion of temperature increase in step S2 of FIG. 6 time t3-1: the completion of first molding in step S3-1 of FIG. 6 time t3-2: the completion of first molding in step S3-2 of FIG. 6 time t4-1: the completion of second molding in step S4-1 of FIG. 6 time t4-2: the completion of second molding in step S4-2 of FIG. 6 time t4-3: the completion of second molding in step S4-3 of FIG. 6 time t5: the completion of return in step S5 of FIG. 6

(49) Referring to FIGS. 6 and 7, the operations of the present embodiment and effects on the molded portion 3a will be specifically described below.

(50) In the enclosed space formation of step S1, first, the punch 2 moves down along an arrow 2a, the plate 4 moves down along an arrow 4a, and the pad 5 moves up along an arrow 5b with the closed valve 17, forming a first enclosed space 6 surrounded by the punch 2, the plate 4, and the film 3 and a second enclosed space 7 surrounded by the die 1, the pad 5, and the film 3.

(51) In the temperature rise of step S2, the punch 2 moves down along the arrow 2a and the pad 5 moves up along the arrow 5b, simultaneously compressing the first enclosed space 6 and the second enclosed space 7 to an equal pressure (Pu=Pl=P2). At this point, high speed compression can prevent thermal diffusion around the enclosed spaces. Moreover, the temperatures of the first and second enclosed spaces 6 and 7 are increased by adiabatic compression to bring a molded portion 3a into an elevated temperature state 3e. For example, in the case of molding in an atmosphere of air with a specific heat ratio of 1.4, a temperature increase from 27 C. (300 K) to 127 C. (400 K) in an enclosed space that is 100 mm in length, 100 mm in width, and 20 mm in depth (a volume of 2010.sup.4 mm.sup.3) may require a compressibility of about 49% (a compressed volume is 9.7410.sup.4 mm.sup.3) based on an expression thermodynamic rule: T [K; temperature]V [mm.sup.3; volume]^ ( [specific heat ratio]1)=constant=39585.24 [Kmm.sup.3].

(52) In the first molding of step S3-1, the punch 2 moves down along the arrow 2a to press the first enclosed space 6 (Pu:P2.fwdarw.P3); meanwhile, the pad 5 is moved down along an arrow 5a while keeping the volume and pressure of the second enclosed space 7. A pressure Pu in the first enclosed space 6 gradually increases while a pressure Pl in the second enclosed space 7 is kept at a constant value P2, gradually increasing a pressure difference to start primary molding.

(53) Furthermore, in the first molding, the punch 2 moves down along the arrow 2a and the pad 5 moves down along the arrow 5a to the molding depth as illustrated in step S3-2. At this point, air flows along an arrow 11 from the second hole 9 provided on the side of the die 1 and the pad 5 stops moving down along the arrow 5a. Since the pressure Pl of the second enclosed space 7 reaches P0 (atmospheric pressure), a pressure difference between the first and second enclosed spaces 6 and 7 rapidly increases, accelerating primary molding.

(54) Hence, the film 3 raised at a temperature T2 (Ta>T2>Tb) at time t3-1 in FIG. 7(d) comes into contact with the punch 2, the die 1, and the pad 5 having lower temperatures at time T4, and then the film 3 is cooled to a temperature T0.

(55) In the second molding of step S4-1, the punch 2 further moves down along the arrow 2a, so that the film 3 is punched by the punch 2, the die 1, and the pad 5. As in the first embodiment, the punch 2, the die 1, and the pad 5 at this point are kept cooled (temperature T0) as shown in FIG. 7(g). Thus, the film 3 at the temperature T2 (Ta>T2>Tb) at time t3-1 in FIG. 7(d) comes into contact with the punch 2, the die 1, and the pad 5 having lower temperatures at time t4-1, and then the film 3 is brought into a cooled state 3d at the temperature T0.

(56) At time t4-1, primary molding is insufficient on a corner (the right side in FIG. 6). Thus, the corner comes into contact with the punch 2 prior to a linear part (the left side in FIG. 6) and is brought into the cooled state 3d. Moreover, the molded portion 3a expanded in contact with the pad 5 by primary molding is also cooled.

(57) In the second molding, as illustrated in step S4-2, the punch 2 continuously moving down along the arrow 2a comes into contact with the linear part (the left side in FIG. 6) to cool the linear part.

(58) Furthermore, in the second molding, as illustrated in step S4-3, when the punch 2 moves down to the bottom dead center along the arrow 2a, the valve 17 is opened. Hence, high temperature and high pressure air in the first enclosed space 6 flows to the outside along an arrow 11a through a pipe 16, so that the film 3 satisfies Tm=T0 (cooled). In this case, the tapered portion 10 on the end of the punch 2 is covered with the material, thereby accelerating cooling.

(59) Finally, in the return of step S5, the valve 17 is opened, the punch 2 moves up along an arrow 2b to the point of origin, and the plate 4 moves up along an arrow 4b to the point of origin. As the punch 2 moves up along the arrow 2b, the first enclosed space 6 is increased in volume and is reduced in pressure, which may cause a dent in the molded portion 3a. At this point, a dent may be prevented by optionally supplying air into the first enclosed space 6 from the first hole 8 along an arrow 11b to increase a pressure.

(60) This configuration can shorten the steps of the series of molding operations, achieving a shorter molding cycle. First, the adiabatic compression of the first and second enclosed spaces 6 and 7 can simultaneously raise the temperatures of the resin layers on the two surfaces of the film 3. Hence, the film 3 in the molded portion 3a can be brought into the elevated temperature state 3e in a short time, achieving higher extensibility.

(61) Moreover, the tapered portion 10 on the end of the punch 2 brings the overall molded portion 3a into contact with the punch 2, accelerating cooling.

(62) Furthermore, a pressure is applied or reduced on the two surfaces of the film 3, thereby easily making a pressure difference. This configuration can effectively suppress variations in production thickness and the occurrence of breaks.

Third Embodiment

(63) FIGS. 8 to 11 illustrate a third embodiment according to the present invention.

(64) The same configurations as in the first embodiment will be indicated by the same reference numerals.

(65) FIG. 8 is a cross-sectional view illustrating an apparatus for molding a metal laminate film. In FIG. 8, a cope Up and a drag Do in FIGS. 9(a) and 9(b) are cut along line A4-A4.

(66) The first and second embodiments are effective for a molded article having a rectangular or complicated shape, and a large ratio of resin layers in a material. In the case of a molded article having a simple shape (e.g., a circle) and a small ratio of resin layers in a material, the occurrence of breaks or wrinkles in a deep molded article can be suppressed by a simple apparatus configuration.

(67) According to the third embodiment, the drag Do includes a die 1 and the cope Up includes a punch 2 as in the second embodiment. The punch 2 and the die 1 are opposed to each other with a film 3 interposed between the punch 2 and the die 1. A plate 4 is attached around the punch 2 of the cope Up while a pad 5 is disposed in the hole of the die 1 of the drag. The punch 2 has a first hole 8. A valve 17 is provided on the first hole 8 via a pipe 16.

(68) Moreover, a pin 12 is operated in synchronization with the operations of the pad 5 and the punch 2, and a cam mechanism 14 is temporarily stopped at the bottom dead center and is returned to the original position as the punch 2 moves up. The cam mechanism 14 is connected to the punch 2 via a cope die set 13 so as to move up or down according to a vertical movement of the punch. The initial position of the pad 5 is set at the same height as the top surface of the die 1. The proximal end of the pin 12 is connected to the cope die set 13 via a buffer spring 21. An operation control unit 30 controls the operations of the drag Do, the cope Up, the punch 2, the pad 5, and so on.

(69) Steps S1, S2, S3-1, S3-2, S4, and S5 in FIG. 10 show a molding process performed by the operation control unit 30 according to the third embodiment.

(70) FIGS. 11(a) to 11(g) show time variations in the shaping rate, pressure, and temperature of a molded article according to the present embodiment. Marks in FIGS. 11(a) to 11(g) are identical to those of FIG. 3 of the first embodiment.

(71) FIGS. 11(a) to 11(g) show the following times: time t1: the completion of enclosed space formation in step S1 of FIG. 10 time t2: the completion of temperature rise in step S2 of FIG. 10 time t3-1: the completion of first molding in step S3-1 of FIG. 10 time t3-1: the completion of first molding in step S3-2 of FIG. 10 time t4: the completion of second molding in step S4 of FIG. 10 time t5: the completion of return in step S5 of FIG. 10

(72) Referring to FIGS. 10 and 11, the operations of the present embodiment and effects on a molded portion 3a will be specifically described below.

(73) In the enclosed space formation of step S1, first, the punch 2 moves down along an arrow 2a and the plate 4 moves down along an arrow 4a with the closed valve 17, forming a first enclosed space 6 surrounded by the punch 2, the plate 4, and the film 3. A second enclosed space 7 surrounded by the die 1, the pad 5, and the film 3 has no volume because no clearance is formed.

(74) In the temperature rise of step S2, the punch 2 further moves down along the arrow 2a to press only the first enclosed space 6 (Pu=P2). High speed compression can prevent thermal diffusion around the enclosed spaces. Moreover, the temperature of the first enclosed space 6 is increased by adiabatic compression to bring the molded portion 3a into an elevated temperature state 3e.

(75) In the first molding of step S3-1, the punch 2 further moves down along the arrow 2a to press the first enclosed space 6; meanwhile, the pad 5 pressed upward by springs 20 starts moving down along an arrow 5a in response to the force of the pin 12 of the cope against the urging force of the springs 20. At this point, a pressure Pl in the second enclosed space 7 is 0 (vacuum) and the first enclosed space 6 has a pressure Pu (=P2). Thus, primary molding is performed according to a pressure difference P2 between the first enclosed space 6 and the second enclosed space 7 (=PuPl).

(76) Furthermore, in the first molding, the punch 2 moves down along the arrow 2a and the pad 5 further moves down along the arrow 5a to a molding depth as illustrated in step S3-2. At this point, the primary molding is completed and the pad 5 stops moving down along the arrow 5a; meanwhile, the cam mechanism 14 acts on the pad 5 so as to stop the pad 5 at the bottom dead center.

(77) After the primary molding, in the second molding of step S4, the punch 2 continuously moves down along the arrow 2a, so that the film 3 is punched by the punch 2, the die 1, and the pad 5. At this point, as shown in FIG. 11(g), the punch 2, the die 1, and the pad 5 are kept cooled (temperature T0). Thus, the film 3 in the elevated temperature state 3e at a temperature T2 (Ta>T2>Tb) at time t3 in FIG. 11(d) comes into contact with the punch 2, the die 1, and the pad 5 having lower temperatures at time t4, and then the film 3 is cooled to the temperature T0.

(78) As in the second embodiment, when the punch 2 reaches the bottom dead center, the valve 17 is opened. Thus, high temperature and high pressure air in the first enclosed space 6 flows out of the apparatus through the pipe 16 along an arrow 11, accelerating cooling on the film 3.

(79) Finally, in the return of step S5, the punch 2 is moved up along an arrow 2b to the point of origin with the opened valve 17 while the plate 4 is moved up to the point of origin along an arrow 4b.

(80) This configuration requires a drive unit for the operations of the second embodiment but eliminates the need for a drive unit for operating the pad 5, achieving a simple mold structure, higher reliability for the mold and the product, and a shorter molding cycle than in the second embodiment.

(81) In order to prevent further shortening of the molding cycle and variations in molded shape, the punch 2, the die 1, and the pad 5 may be provided with a cooling mechanism including the passage of a heat exchange medium, e.g., cooling water or compressed air.

(82) A rapid temperature change may accelerate material deterioration depending on the kind of the film 3. In this case, a thin thermal barrier for gradually reducing a temperature may be provided in each of the punch 2, the die 1, and the pad 5 so as to provide a mechanism for gradually dissipating heat.

(83) In the foregoing embodiments, air is contained in the first and second enclosed spaces 6 and 7. The first and second enclosed spaces 6 and 7 may contain other kinds of gas, specifically, inert gas such as nitrogen.

(84) The present invention is applicable to a battery package having a complicated shape for protecting an interior part over an extended period or a protective sheet for an electronic component. The present invention is also applicable to the field of manufacturing wrapping materials and containers for agents and food products with metal laminate films.