JP3908518B2 - Method for producing resin-coated metal seamless can body - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
In the present invention, a cup-shaped intermediate material obtained by drawing a metal plate coated on both sides with a thermoplastic resin is subjected to redrawing or redrawing ironing or ironing with a punch and a die. The present invention relates to a method of manufacturing a seamless can body with a head.
[0002]
[Prior art]
In general, metal cans (containers) made of aluminum or steel are roughly classified into three-piece cans, two-piece cans, and bottle-type cans according to their shapes. The three-piece can is called a three-piece can because it consists of a bottom lid, a can body joined by welding or adhesion, and a canopy. In addition, the two-piece can is a structure in which a canopy is attached to a can body in which the bottom of the can is integrated. The two-piece can is referred to as a two-piece can because the can body and the canopy are two constituent members. It is also called a seamless can because it has no seams. Furthermore, the bottle-shaped can is composed of a side seamless can body having a threaded portion formed at one open end of the can body, a cap and a bottom cover screwed to the threaded portion, and the overall shape is glass. It is called a bottle-shaped can because it is close to a bottle made of plastic.
[0003]
In any of these metal cans, a protective layer made of a synthetic resin is formed on the inner surface of the can in order to ensure corrosion resistance. In recent years, a laminated can having a coating made of a thermoplastic resin as a protective layer has been developed and put into practical use. This type of laminated can is made of a resin film-covered metal plate obtained by laminating a resin film on a metal material, and is often formed into a can body by deep drawing or drawing and ironing. In order to obtain a two-piece can body, since the amount of deformation or the degree of processing of the material is large, a high molding technique is required.
[0004]
That is, the merit of the laminate can depends on the organic resin film to be applied, but it is excellent in content resistance, particularly in flavor such as taste and flavor of the contents. On the other hand, as a disadvantage, it is a problem in can manufacturing, but because the processing degree (or forming degree) of the thermoplastic resin film metal plate is large, the inner resin film is scratched during molding, and the quality of the inner surface of the can Therefore, it is necessary to strictly inspect the quality of the can body, and the product yield is inferior to that of a general paint can.
[0005]
In particular, in the case of a two-piece type laminate can using a steel material, the tendency is remarkable, but the same thing occurs in an aluminum material laminate can. Such a defect of the resin film on the inner surface of the laminated can enters at the time of can molding as described above, and minimizing this defect is an important issue in terms of quality and product yield.
[0006]
More specifically, a cup-shaped intermediate material formed by drawing a metal plate coated with a thermoplastic resin on both sides is redrawn, redrawn or ironed with a punch and a die, and seamless with a bottom. When manufacturing the can body, unlike the conventional seamless can manufacturing method using a material without resin coating, there is no washing process in the subsequent process, so coolant (coolant) is applied to the outer surface of the can body side wall during processing and molding. I can not use it. For this reason, the temperature of the punch and the die rises as the number of cans is increased immediately after the start of production, but the temperature of the punch suddenly rises compared to the die, and the clearance between the punch and the die is increased by the expansion of the punch. There are cases where the wall thickness of the can body immediately after the start of production is reduced, or the wall thickness and the width of the can body vary in the circumferential direction of the can body. For this reason, the can body manufactured until the temperature rise of the punch is stabilized needs to be discharged out of the system as a defective can, and the manufacturing efficiency may be reduced due to the broken cylinder, which increases the manufacturing cost. It was a factor.
[0007]
The laminate can is also manufactured by redrawing or redrawing ironing or ironing a cup-shaped intermediate material composed of a coated metal plate coated with a thermoplastic resin film as described above, and the manufacturing process 2. Description of the Related Art As a device that can prevent a broken cylinder, a crack in a coating resin, and the like, a device configured to control the temperature of a forming tool is known. This type of apparatus is described in, for example, Japanese Patent Application Laid-Open No. 1-278921 (Japanese Patent Publication No. 7-57388), Japanese Patent Application Laid-Open No. 6-210381, Japanese Patent Application Laid-Open No. 7-275961, and the like.
[0008]
Briefly explaining the invention described in these publications, the method described in JP-A-1-278921 is a method for producing a container in which the temperature of the punch during the process is maintained at a temperature of 50 ° C. to 80 ° C. . In addition, the method described in Japanese Patent Laid-Open No. 6-210381 is a method for producing a seamless can by redrawing a laminated metal plate having a polyester film laminated on both sides thereof, in a die (or in a die and a wrinkle presser). ), And the hot water is switched to cold water just before the start of processing so that the surface temperature of the die facing the wrinkle presser (or the wrinkle presser facing the die) is maintained at 40 to 100 ° C. during the processing. It is the method. Further, the invention described in Japanese Patent Application Laid-Open No. 7-275961 heats the inside of the die, the wrinkle presser and the punch before the molding operation, switches the heating to cooling immediately before the molding starts, continues cooling during molding, This is a method for manufacturing a seamless can in which the surface temperature of the inner die, the wrinkle presser and the punch, and the punch surface temperature immediately after extraction are kept within a predetermined temperature range.
[0009]
[Problems to be solved by the invention]
Each of the above-described conventional inventions is a method of adjusting the temperature of an apparatus for manufacturing a seamless can by controlling the temperature of water flowing through the forming tool or switching the fluid flowing through. There is a problem like this.
[0010]
First, in the invention described in Japanese Patent Application Laid-Open No. 1-278921 (Japanese Patent Publication No. 7-57388), a liquid circuit is formed in a punch, and a coolant is passed through the liquid circuit to exchange heat from the inside of the punch. Therefore, there is a problem that the temperature control reaction by the coolant is dull with respect to the rapid temperature change of the punch surface, and it is difficult to perform the temperature control with high sensitivity. Moreover, in order to suppress the temperature rise due to heat generated by the punch by letting the coolant flow, it is necessary to improve the heat exchange efficiency by the liquid and to allow as much coolant as possible to flow through the water flow circuit. Since the water flow circuit is hollow due to its structure, it causes a decrease in strength. Therefore, considering the punch strength, the length of the water flow circuit and the cross-sectional area of the water flow channel are limited in space and cooling performance is reduced. There is a problem that the temperature distribution of the punch is not uniform, not necessarily sufficient.
[0011]
On the other hand, in the invention described in Japanese Patent Application Laid-Open No. 6-210381 (Japanese Patent No. 2550845) and Japanese Patent Application Laid-Open No. 7-275961 (Japanese Patent No. 2790072), hot water flowing into the die immediately before the start of processing. By switching to cold water, the upper surface temperature facing the wrinkle presser of the die is appropriately maintained at a temperature (40 to 100 ° C.) to perform redrawing. Therefore, similar to the invention of the above-mentioned Japanese Patent Application Laid-Open No. 1-278921 (Japanese Patent Publication No. 7-57388), it takes time for heat exchange, the cooling reaction to the rapid temperature change of the punch surface is slow, and the temperature is high. There is a problem that control is difficult. Also, when switching hot water flowing through the die to cold water, water for temperature adjustment is supplied and circulated from the outside of the die through the die holder to each forming tool, for example, for multiple picking, In the case of a mold structure in which a plurality of forming tools can be attached to a common die holder, the temperature of the die holder itself, which has been warmed through warm water until just before the start of production, is changed by switching from hot water to cold water. It is easy to distort due to change, and accordingly, the punch attached to the upper die and the die attached to the lower die are misaligned, which causes variations in the wall thickness of the can barrel, There is a problem that it is easy to do.
[0012]
Similarly, when switching from hot water to cold water in the die, uniform cooling is difficult to be performed over the entire circumference, and the die is also distorted, and as a result, the roundness of the die is easily lost. As a result, there is a problem that the wall thickness of the can body varies, and it is easy to break.
[0013]
The present invention has been made paying attention to the technical problems described above, and when a resin-coated metal-made seamless can with a flange is produced by subjecting a cup-shaped intermediate material to drawing or redrawing ironing, etc. Furthermore, it is an object of the present invention to provide a method capable of improving the uniformity of the can wall at the start of its production or at the time of resumption after being interrupted and preventing defects such as fraying.
[0014]
[Means for Solving the Problem and Action]
  In order to achieve the above object, the invention of claim 1 is characterized in that a cup-shaped intermediate material formed by drawing a resin-coated metal plate coated with a thermoplastic resin on both sides of a metal plate is formed by a punch and a die. In a method of manufacturing a resin-coated metal seamless can body that is redrawn or redrawed and ironed or obtained by ironing to obtain a seamless can body having a bottom with a flange, the continuous production of the seamless can body is interrupted before the start of the production. During idle driving, in the punch or die2Circulating constant temperature water at a constant temperature of 0 ° C to 80 ° CLet it heat or keep warm from the inside,Add the punch from the outsideBy heatingThe punch surface temperature is higher than the temperature of the cup-shaped intermediate material before processing, and is raised to the vicinity of the punch arrival temperature during continuous production.Heating from the outer surface side ofFirst, a punched seamless can barrel is formed using a heat storage punch, the punch is lowered to the bottom dead center, and cooled from the outer surface side of the hooked seamless can barrel that is fitted to the punch. Then, the punch is cooled through the can body, and in the ascending process of the punch, the surface temperature of the outer surface resin film of the can body is made below the glass transition point of the resin, and the can body and the die The method is characterized in that the engagement state is relaxed and the can body is pulled out from the die.
[0015]
  In other words, the invention of claim 1 allows for the temperature change at the time of the punch start-up at the start of manufacture, and before the start of continuous manufacture, the punch surface temperatureFrom the outsideHeat it up and punch it almost simultaneously with the start of production.From outsideBy stopping the heat, it is intended to suppress the generation of defective cans immediately after the start of production. Therefore, according to the first aspect of the present invention, the punch during idling is heated from the outer surface side before the start of continuous production of the seamless can shell with a flange or during idling during production interruption, and the punch surface temperature is set before the processing. The temperature is higher than the temperature of the cup-shaped intermediate material, and the temperature is raised near the temperature reached by the punch during continuous production.From outsideBy stopping the heat and starting or restarting manufacturing using the punch in the heat storage state, it becomes possible to reduce the change in the temperature rise curve of the punch immediately after the start of manufacturing or immediately after the restart of manufacturing. In other words, heat is removed from the punch to the cup-shaped intermediate material, while the heat generated by the can body forming process is compensated for. There is little change in the punch temperature before and after, and it is possible to maintain a temperature close to the ultimate temperature of the punch during continuous production, so the change in punch diameter can be reduced, and when starting from the start (or restart) of production The number of defective cans can be reduced, and the change over the entire circumference in the length of the can of the seamless can body can be reduced, thereby preventing the occurrence of flaws during processing.
[0016]
In addition, the entire peripheral surface of the punch retracted from the die during the idling operation is heated by applying heat almost uniformly. For this reason, the variation in the wall thickness in the circumferential direction of the can body of the metal can body immediately after the start of manufacture is reduced, and the thermoplastic resin coating can be prevented from being galled or broken.
[0017]
Even when continuous production is interrupted for a short time or when the interruption occurs in pieces, the outer peripheral surface of the punch can be quickly and directly heated from the outer surface side to supply heat. Responsiveness to changes is improved.
[0019]
Furthermore, in claim 1In the invention, constant temperature water of 20 ° C. to 80 ° C. is circulated through the punch and the die to heat and keep them, and in that state, the punch is further heated from the outside. Even if the environmental temperature in which the can body molding equipment is placed differs between summer and winter, the temperature difference between the temperature at the start of production (restart) and the temperature reached at the punch during continuous production is not affected by the temperature environment. It can be made almost constant, and it becomes easy to control the heating temperature of the punch during the idling operation.
[0021]
And claim 1According to the invention, the punch is cooled from the outside of the can body in a state where the punch is lowered and the can body is redrawn or redrawn and ironed or ironed. Therefore, during continuous production, the final stage of the punch advancement process, that is, near the bottom dead center of the punch stroke, the can body that is fitted to the punch is cooled from the outer surface side to be molded and fitted into the punch. The can body is being cooled, and the punch is also cooled through the can body.RejectIn the punch returning (raising) step, the engagement state of the die is relaxed to make it easier to pull out the hooked seamless can body from the inside of the die, and the surface temperature of the outer resin film is made to be equal to or lower than the glass transition point (Tg) of the resin.RuTherefore, it is possible to suppress the resin film from being softened by the processing heat and to prevent the resin from sticking to the surface of the punch, making it easy to strip the flanged seamless can body from the punch and preventing galling of the outer surface resin film. .
[0022]
Also,ClaimItem 2The invention claims1'sIn the invention, at least the body wall of the cup-shaped intermediate material before processing is preheated to 20 ° C to 80 ° C.
[0023]
  Therefore billingItem 2In the invention, the body wall of the cup-shaped intermediate material to be subjected to redrawing or redrawing ironing or ironing is heated in advance to 20 ° C. to 80 ° C., so that it is molded near the glass transition temperature of the resin coating. In addition, the can body can be easily stripped from the punch, and the moldability can be improved.
[0024]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail based on specific examples shown in the drawings. First, an example of a seamless can body targeted in the present invention is a bolt-shaped can body having a cap on the mouth and neck, which is manufactured through the process shown in FIG. 1, for example.
[0025]
As the material of this seamless can body, a resin-coated metal plate laminated with thermoplastic resin on both sides is used, and this is punched into a disk shape in the cup molding process to make a blank, and the blank is drawn into a cup shape. The intermediate material is formed. In the next can body forming process, this cup-shaped intermediate material is subjected to at least one redrawing process, redrawing ironing process or ironing process to form a cylindrical can with a bottom having a small diameter and a thin wall. Mold on the barrel. In that case, bending and stretching may be performed at the same time.
[0026]
Next, in the top dome forming step, in order to form the can bottom side of the bottomed cylindrical can body into the mouth neck portion and the shoulder portion, first, in the first step, the can bottom corner portion in the above can body (Bottom part and cylindrical part near the bottom part) are molded into a curved surface of the lower part of the shoulder with an arc-shaped longitudinal section, and a small-diameter bottomed cylindrical part is drawn and formed on the bottom side of the can in the second to third steps. On the other hand, the diameter of the bottomed cylindrical portion is reduced until it becomes substantially the same as the diameter of the mouth-and-neck portion by performing drawing processing a plurality of times. Further, in the fourth step, the shoulder portion formed following the initial shoulder lower curved surface by repeating such drawing is reshaped (reformed) into a continuous smooth curved surface. In the fifth step and the sixth step, the bottomed cylindrical portion formed to have the same diameter as the mouth and neck portion is subjected to two times of mouth drawing.
[0027]
The lubricant adhering to the can body formed in the top dome forming step with the opening and neck portion and the shoulder portion with the unopened can bottom side removed in the next lubricant removing step. In the subsequent trimming step, the opening end side of the body part opposite to the mouth and neck part is trimmed to make the can a predetermined length. Furthermore, in the printing / painting process, the desired design (letters, decorative patterns, etc.) is printed on the outer surface of the cylindrical body whose end opposite to the mouth / neck is open, and the printing is performed. A transparent curable paint (clear paint) for protecting the outer surface of the can is applied as a top coat to the outer surface of the body. This printing and painting process is the same as the printing and painting process for the cylindrical body of a normal two-piece can.
[0028]
The can body that has been printed and painted is sent to the next drying step to sufficiently dry the printing ink layer and the top coat layer. In this drying step, the laminated thermoplastic resin layer is heated and melted to a temperature equal to or higher than its crystal melting temperature, and then made amorphous by cooling to 160 ° C. within 8 seconds. After that, in the screw / curl molding process, first, the front neck closed portion of the unopened mouth / neck portion is trimmed to open the mouth / neck portion, and the open end portion is externally wound (or internally wound) to form an annular curled portion. Then, a screw for screwing a cap is formed on the cylindrical peripheral wall, and then a bead portion is formed below the screw forming portion.
[0029]
Then, in the neck / flange molding process, neck-in processing and flange processing are sequentially performed on the lower end opening end of the body portion opposite to the mouth / neck portion. The bottle-shaped can body thus obtained is sent to a bottom lid tightening step (not shown), and a bottom cover of another member made of a metal plate is attached to the bottom end opening of the body portion by a seamer (can lid tightening machine). The bottle-shaped can is completed by being integrally fixed to the flange portion formed by the double winding method.
[0030]
Here, the resin-coated metal plate that can be used in the present invention will be described. The metal plate to be resin-coated is not particularly limited, and an aluminum alloy plate or various surface treatments such as metal plating and chemical conversion treatment are performed. Surface-treated steel sheets such as ultrathin tin-plated steel sheets, nickel-plated steel sheets, electrolytic chromic acid-treated steel sheets, and galvanized steel sheets can be used. As the surface treatment, it is desirable to use a surface-treated metal plate for the purpose of ensuring adhesion with the thermoplastic polyester resin film.
[0031]
For example, chromic acid chromic acid treatment or zirconium phosphate treatment, which is used as a surface treatment after molding of ordinary drawn iron cans, is applied. In the case of a processing degree, an organic-inorganic composite chemical conversion treatment of phosphoric acid or zirconium phosphate and an organic resin is effective. Specifically, for example, an aluminum alloy plate having a thickness of 0.24 mm to 0.38 mm, and 3004 series or 3104 series aluminum alloy specified by Japanese Industrial Standards (JIS), 1 to 40 mg / m of chromium.² , Treatment with adhering phosphate chromate, or zirconium 4-17 mg / m² In addition, a material subjected to a chemical conversion treatment such as an attached zirconium phosphate treatment is used.
[0032]
The steel plate in the present invention is a surface-treated steel plate having a thickness of 0.15 mm to 0.25 mm, for example, and the amount of adhesion on one side is 20 to 2000 mg / m on both sides of the steel plate.² Nickel plating layer, 1 mg / m as the amount of C attached to one side on the upper layer² To 100mg / m² Those having a chemical conversion treatment film layer mainly composed of the above organic resin are used. In addition, the steel plate before nickel plating and chemical conversion treatment is not specifically limited, What is normally used as a steel plate for cans is applied.
[0033]
As the resin film coated on the metal plate, a thermoplastic polyester resin film having good heat resistance and characteristics suitable for can applications is used. Examples of the polyester resin include polyethylene terephthalate (PET) and polybutylene. Homopolymers such as terephthalate (PBT) and polyethylene isophthalate (PEI), copolymers such as copolymers of polyethylene terephthalate and polyethylene isophthalate, blends of such homopolymers, homopolymers and copolymers, etc. Examples thereof include blends and blend resins of copolymers.
[0034]
Further, the melting point of the thermoplastic polyester resin used in the present invention can be appropriately selected depending on the degree of the copolymer, the selection of the resin to be blended and the blend ratio thereof. For example, the melting point (Tm) is 200 ° C. to 260 ° C. The resin film is applied. In addition, the resin-coated metal plate of the present invention is made amorphous after being laminated, after being heated and melted above the melting point of the thermoplastic resin film that has been thermally bonded, and then rapidly cooled below the glass transition point. A resin-coated metal plate in which biaxially oriented crystals remain on the upper layer side of the thermoplastic resin coating layer may be used.
[0035]
The method of the present invention can be carried out in the can body forming step among the steps from the cup forming step to the neck / flange forming step. 2 and 3 schematically show an example of an apparatus used for carrying out the method of the present invention in redrawing, redrawing ironing or ironing in the can body forming process. It is configured as a press die. That is, the inner slide 1 and the outer slide 2 are arranged so as to be vertically movable, and the intermediate plate 3 is fixedly arranged below the outer slide 2 and further below the stroke range of the outer slide 2. A die holder 4 is fixed below the intermediate plate 3, and the die holder 4 is held by a die base 5 disposed below the die holder 4.
[0036]
A nose holder 6 is fixed to the lower surface of the inner slide 1, and a punch drive shaft 7 is attached to the nose holder 6 in a suspended manner. A punch 9 is attached to the lower end portion of the punch drive shaft 7 for processing to reduce the thickness of the body wall of the cup-shaped intermediate member 8 made of a resin-coated metal plate.
[0037]
The punch 9 is composed of a core material 9a and a sleeve 9b closely fitted to the outer periphery thereof, and at least the sleeve 9b is made of cemented carbide. A spiral flow path 10 is formed at the boundary between the core material 9a and the sleeve 9b, and the water supply / drain path 11 formed through the nose holder 6 and the punch drive shaft 7 is formed in the flow path 10. Is communicated. And this water supply / drainage path 11 is connected to the heat source part (not shown) which circulates, for example, 20-50 degreeC constant temperature water.
[0038]
The outer slide 2 is formed with an opening through which the punch drive shaft 7 and the punch 9 penetrate, and a piston 12 that operates in the vertical direction is provided in the vicinity of the inner periphery of the opening, and is integrated with the piston 12. The pusher pin 13 that moves in a straight line extends downward and a wrinkle presser 14 is attached to the tip (lower end) thereof. The wrinkle presser 14 is a hollow cylindrical member having an opening having a diameter larger than that of the punch 9, and presses the flange (saddle) of the cup-shaped intermediate member 8 with the tip (lower end) thereof. It is configured as follows.
[0039]
Further, the intermediate plate 3 is formed with a through-hole having a diameter larger than that of the wrinkle presser 14, and a wrinkle presser guide 15 having a cylindrical shape is attached to the through-hole. The pusher pin 13 passes through the wrinkle presser guide 15, and the punch drive shaft 7 passes through an opening formed at the center of the wrinkle presser guide 15.
[0040]
A heat source sleeve 16 is attached to an opening formed in the wrinkle holding guide 15. The heat source sleeve 16 is for heating the punch 9 from the outer surface side, and is configured to blow out hot air or hot air from the inner surface, a cylindrical body with a built-in heating wire, a cylindrical body with a built-in electromagnetic induction coil. It has a cylindrical structure. The heat source sleeve 16 is set to a length for heating the punch 9 located at the top dead center.
[0041]
A die 17 for forming a can body together with the punch 9 is attached to the die holder 4 by a presser plate, and is held so that automatic alignment can be performed along the entering punch 9. The die 17 is an annular plate-like member formed around the opening for molding, and a predetermined clearance is generated between the inner diameter of the opening and the outer peripheral surface of the punch 9. It is a dimension. More specifically, as shown in FIG. 4, the opening in the die 17 includes, in order from the top, a tapered introduction portion 17 a that spreads upward, and a machining portion that is parallel to the central axis and has a predetermined axial length. 17b and a taper-shaped relief portion 17c that extends downward and is connected to the lower side of the processed portion 17b. Therefore, the part which contacts the said cup-shaped intermediate material 8 which is a workpiece is limited to the process part 17b and its vicinity, Therefore, the location which generate | occur | produces a heat | fever with a shaping | molding process, and the location which receives heat with respect to the whole die | dye 17 Limited to a narrow range.
[0042]
Further, a flow path 18 for flowing a temperature adjusting fluid is formed substantially concentrically with the processed portion 17b inside the die 17, and a water supply / drainage channel formed in the die holder 4 to which the die 17 is attached. 19 communicates with the lower surface of the die 17. This flow path 18 is connected to a heat source part (not shown) so as to circulate and supply, for example, constant temperature water of 20 to 80 ° C., similarly to the water supply / drainage path 11 in the punch 9.
[0043]
A cooling sleeve 20 for cooling from the outer surface side is disposed below the die 17 together with a molded body (can body as an intermediate product) fitting the punch 9 lowered to the bottom dead center. Yes. The cooling sleeve 20 is for removing heat generated by redrawing, redrawing ironing, or ironing to cool the can body and the punch 9. As an example, the cooling sleeve 20 is on the inner peripheral side of the cooling sleeve 20. It is comprised so that cold wind may be blown out toward. The cooling sleeve 20 has an inner diameter slightly larger than the outer diameter of the can body fitted to the punch 9 at the bottom dead center, and at least a portion of the can body extending downward from the die 17. The length is set to surround the whole.
[0044]
2 and 3, reference numeral 21 denotes a knockout, which is arranged on the same axis as the punch 9 so as to be vertically movable below the punch 9.
[0045]
Next, the method of the present invention using the apparatus constructed as described above will be described. Even before the start of the forming process or when the supply of the cup-shaped intermediate material 8 is stopped (so-called idle operation), the flow path 10 of the punch 9 and the flow path 18 of the die 17 are set to 20 ° C. to 80 ° C. The constant temperature water at a constant temperature is continuously supplied and heated or kept warm from the inside. In addition, the surface (outer peripheral surface) of the punch 9 is heated and kept warm by the heat source sleeve 16 provided on the top dead center side of the punch 9. The temperature is higher than the temperature of the cup-shaped intermediate material 8 before processing sent from the previous process, and is a temperature in the vicinity of the punch surface temperature reached when a large number of cup-shaped intermediate materials 8 are continuously formed. is there. As an example, it is 50 degreeC-120 degreeC.
[0046]
Here, the temperature of the cup-shaped intermediate material 8 before processing is generally the ambient temperature in the factory where the above-described apparatus is installed, or is somewhat higher than the ambient temperature due to the residual heat in the previous process. And can be determined in advance. Further, the surface temperature reached by the punch 9 during continuous processing (during continuous production) varies depending on the processing speed, the type of material, the processing amount, the material of the tool such as the punch 9 and the die 17, etc. The processing conditions can be determined and measured in advance.
[0047]
Since the punch 9 is kept warm by the constant temperature water as described above, the temperature hardly changes depending on the season. Therefore, the temperature control of the punch 9 by the heat source sleeve 16 is almost constant. By being, it can be done easily and accurately. In other words, variations in the surface temperature of the punch 9 due to the season and atmospheric temperature are reduced.
[0048]
In this way, the punch 9 and the wrinkle presser 14 are pulled up to the top dead center in the state where the punch 9 is heated and kept warm from the outer surface side and the die 17 is kept warm with constant temperature water. The cup-shaped intermediate material 8 formed in the above is set on the die 17. The punch 9 and the wrinkle presser 14 are lowered with respect to the cup-shaped intermediate material 8 and subjected to redrawing processing or redrawing ironing processing or ironing processing. Before the punch 9 is lowered, the operation of the heat source sleeve 16 is performed. Is stopped, and heating and heat insulation of the punch 9 are stopped.
[0049]
Next, clutches (not shown) of the press machine are turned on, and the inner slide 1 and the outer slide 2 are lowered. As a result, the wrinkle presser 14 first sets the cup-shaped intermediate material 8 by sandwiching the flange of the cup-shaped intermediate material 8 between the upper surface of the die 17. In this state, the lowering of the outer slide 2 is stopped, but the inner slide 1 is further lowered, so that the punch 9 attached thereto enters the inside of the cup-shaped intermediate member 8 fixed to the die 17, The can body molding is performed on the cup-shaped intermediate member 8 together with the die 17.
[0050]
In that case, the above-mentioned constant temperature water is supplied to the dice 17 and is maintained at a predetermined temperature. Therefore, the clearance between the punch 9 and the die 17 at the start or resumption of the forming process is maintained at a desired dimension. The resin coating formed on both the inner and outer surfaces of the cup-shaped intermediate material 8 is molded in a state where it is appropriately held within the allowable temperature range for sliding and extending in contact with the punch 9 and the die 17. Therefore, defects such as variations in the thickness of the cylinder wall, broken cylinders, ruptures of ridges, and cracks in the resin coating are prevented or suppressed.
[0051]
On the other hand, when the processing of the cup-shaped intermediate member 8 set on the die 17 is started, the cooling sleeve 20 is operated, and thus the punch 9 lowered to the bottom dead center is fitted to this. Along with the body (cup-shaped intermediate member 8), it is cooled from the outer surface side. That is, when the punch 9 performs thinning molding on the cup-shaped intermediate material 8, processing heat is generated due to frictional heat, extension of the material of the cup-shaped intermediate material 8, etc., but at least a part of the heat is a cooling sleeve. 20 is taken away by operating. As a result, the cup-shaped intermediate member 8 and the punch 9 are relatively cooled and easily maintained in a predetermined temperature range.
[0052]
  When the punch 9 is lowered to the bottom dead center in this way, the thinning molding is finished. First, the punch 9 is lifted together with the inner slide 1, and then the wrinkle presser 14 is lifted, and the wrinkle presser 14 is lifted or wrinkle presser is pressed. Knockout with 14 ascentG 21Ascending, the can body is pushed upward from the die 17. In this case, since the can body fitted to the punch 9 is cooled by the cooling sleeve 20, the fitting with the die 17 is eased.RanoIt becomes easy to knock out (releasability). Further, since the surface temperature of the resin film formed on the can body can be made lower than the glass transition point (Tg) of the resin, the resin is softened by processing heat and sticks to the surface of the punch 9. This can be suppressed or prevented, so that the can body which is a molded product can be easily stripped from the punch 9, and at the same time, damage due to galling of the resin coating can be prevented.
[0053]
In addition, the can body as a molded product obtained in this way is sent to the next ironing process which is not illustrated.
[0054]
In addition, since the cup-shaped intermediate material 8 is sent at short time intervals, the above-described molding process of the body wall is repeatedly executed according to the supply speed of the cup-shaped intermediate material 8, and during the processing, the punch 9 is applied to the punch 9. Is supplied only with the constant temperature water, and is not heated by the heat source sleeve 16. In the process, when the molding of the body wall is interrupted due to the interruption of the supply of the cup-shaped intermediate material 8 or the like, the punch 9 is in a so-called idle operation state in which the punch 9 simply moves up or down, or the clutch of the press machine. May be turned off and the punch 9 may stop at the top dead center. In this case, the punch 9 is heated and kept warm by the heat source sleeve 16 after a timely timer to prepare for the restart of the next forming process.
[0055]
Therefore, in the above method according to the present invention, before the punch 9 starts the substantial forming process of the cup-shaped intermediate material 8, the temperature of the punch 9 is set higher than the temperature of the cup-shaped intermediate material 8 and continuously. Since the temperature is set in the vicinity of the ultimate temperature at the time of forming, the clearance between the punch 9 and the die 17 at the start or restart of the forming process has the desired dimensions, and the relative misalignment. Therefore, molding defects such as fluctuations in the wall thickness, broken bodies, broken or cracked ridges are eliminated. Moreover, since the temperature of the resin coating provided on the surface of the cup-shaped intermediate material 8 can be set to a temperature suitable for processing, the occurrence of defects such as cracks and breaks in the resin coating can be prevented. That is, since the defective product occurrence rate at the start or restart of the molding process can be reduced, the material yield or productivity can be improved.
[0056]
Further, processing heat is generated along with the forming process. When the punch 9 is lowered to the bottom dead center, the punch 9 is cooled by the cooling sleeve 20 together with the can body fitted on the outer periphery thereof, and the processing heat is generated. At least part of it is taken away. Therefore, even if the molding process is continuously performed, the temperature of the punch 9 does not become abnormally high and is maintained at a predetermined temperature. In particular, since the temperature control of the punch 9 is performed by cooling or heating the entire surface uniformly from the outer surface side by the cooling sleeve 20 or the heat source sleeve 16 as described above, the responsiveness of the temperature control is good and the temperature varies. Less.
[0057]
Here, the results of experiments conducted by the present inventors are shown in FIGS. The molding process to be measured was a cup-shaped intermediate material having a height of 48 mm and an outer diameter of 100 mm obtained by drawing a 170 mm diameter blank from a thermoreversible polyester resin film-coated aluminum alloy plate (0.12 mm). Is redrawn and ironed into a bottomed cylindrical can body having a height of 171.5 mm and an outer diameter of 65.9 mm.
[0058]
FIG. 5 is a diagram showing the results of measuring the change in punch temperature after the start of molding at 100 SPM. The solid line indicates an example of the present invention, and the broken line indicates a conventional example in which heating from the outer surface side by the heat source sleeve 16 is not performed. Show. As is clear from the measurement results shown in FIG. 5, in the method according to the present invention, the punch temperature is maintained at the temperature during continuous molding from the beginning of molding. Therefore, molding defects caused by temperature conditions such as a temperature difference with the die 17 and a temperature change of the punch 9 can be suppressed or avoided.
[0059]
FIG. 6 is a diagram showing the results of measuring changes in the wall thickness of the can body, and an example using a sleeve for induction heating as the heat source sleeve 16 and an example using a band heater incorporating a heating wire. The measurement result about the prior art example which does not heat with the heat source sleeve 16 is shown. As is apparent from the measurement results shown in FIG. 6, it was confirmed that the method according to the present invention has a small change in the thickness of the can barrel wall after the start of molding and can perform good redraw ironing.
[0060]
In the above specific example, the punch 9 and the die 17 are heated, kept warm, and cooled. However, in the method of the present invention, the temperature of the cup-shaped intermediate material 8 that is a molding object may be controlled. . For example, it is preferable that the temperature of at least the body wall of the cup-shaped intermediate member 8 is heated and kept at 20 ° C. to 80 ° C. before starting the processing. By doing so, the lubricity of the resin coating formed on the surface is improved, and the molding is performed near the glass transition temperature of the resin, so that the moldability is improved.
[0061]
Further, in the above specific example, the example of performing redrawing and ironing has been described. However, the present invention is not limited to the above specific example, and is applicable to any processing of redrawing, stretch forming, and ironing. be able to. Further, the heat source output of the band heater and the induction heating coil can be controlled so that it can be appropriately changed according to the material of the punch and the distance and length between the heat source sleeve and the punch.
[0062]
【The invention's effect】
As described above, according to the present invention, there is little change in the temperature of the punch during the start-up when continuous production is started from the idle operation state of the punch, that is, before and after the start of production. Because the temperature can be kept close, changes in the outer diameter of the punch can be reduced, the number of defective cans at the start-up (or resumption) from the start can be reduced, and the entire circumference of the seamless can barrel length Therefore, it is possible to prevent the occurrence of flaws during processing. Moreover, since the heat is applied almost uniformly to the entire peripheral surface of the punch that has been retracted from the die during idling, there is less variation in wall thickness in the circumferential direction of the can body of the metal can body immediately after the start of production. Further, it is possible to prevent the thermoplastic resin film from being galled and broken. In addition, even when continuous production is interrupted for a short time or when the interruption occurs in pieces, the outer peripheral surface of the punch can be quickly and directly heated from the outer surface side, which makes it responsive to temperature changes. Get better.
[0063]
  Also, This departureAccording to Ming, the punch and die are heated and kept warm, and in that state, the punch is further heated from the outer surface side, so even if the environmental temperature where the molding equipment is placed differs between summer and winter Regardless of the temperature environment, the temperature difference between the temperature at the start of production (resumption) and the punch arrival temperature at the time of continuous production can be made substantially constant, and the heating temperature of the punch during idle operation can be easily controlled.
[0064]
  further, This departureAccording to Ming, during continuous manufacturing, the final stage of the punch advancement process, that is, near the bottom dead center of the punch stroke, is formed by cooling the can body that is fitted to the punch from the outer surface side. It is possible to cool the can body fitted to the punch, and also to cool the punch through the can body. In the punch returning (raising) process, the engagement state of the die is relaxed and the seamless can with a hook The cylinder can be easily pulled out from the die, and the surface temperature of the outer resin film can be made lower than the glass transition point (Tg) of the resin, so that the resin film is softened by processing heat and the resin adheres to the surface of the punch. This makes it possible to easily strip the flanged seamless can body from the punch and prevent galling of the outer resin film.
[0065]
  And, This departureAccording to Ming, the body wall of the cup-shaped intermediate material that is subjected to drawing or redrawing ironing or ironing is preheated to 20 ° C to 80 ° C, so that it is molded near the glass transition temperature of the resin coating. The moldability can be improved, and the releasability can be improved by keeping the temperature of the cup-shaped intermediate material constant.
[Brief description of the drawings]
FIG. 1 is a process diagram schematically showing an example of a molding process of a seamless can body targeted in the present invention.
FIG. 2 is a cross-sectional perspective view schematically showing an example of an apparatus used in the can body forming process.
3 is a schematic cross-sectional side view of the apparatus shown in FIG. 2. FIG.
FIG. 4 is an enlarged cross-sectional view of a die forming part.
FIG. 5 is a diagram showing a measurement result of a change in punch temperature in comparison between an example of the present invention and a conventional example.
FIG. 6 is a diagram showing measurement results of changes in can body wall thickness by comparing the example of the present invention with a conventional example.
[Explanation of symbols]
  8 ... Cup-shaped intermediate material, 9 ... Punch, 10, 18 ... Flow path, 16... heat sourceReeve, 17 ... dice.

Claims (2)

A cup-shaped intermediate material formed by drawing a resin-coated metal plate coated with a thermoplastic resin on both sides of the metal plate is redrawn or redrawn or ironed with a punch and a die. In the method for producing a resin-coated metal seamless can body to obtain a bottom-like seamless can body,
Before starting production of the seamless can body or during idle operation where continuous production is interrupted, constant temperature water of 20 ° C. to 80 ° C. is circulated through the punch or die to heat from the inside or as well as thermal insulation, by pressurized heat the punch from the outer surface side, keep the punch surface temperature higher than the temperature of the cup-shaped intermediate material before processing, and allowed to warm to punch reaches a temperature near the time of continuous production, production immediately before or heating from the outer surface side of the punch just before production resumed stop Umate, molding a flanged seamless can body with a punch in the heat storage state, descends the punch to the bottom dead center, the punch Cooling from the outer surface side of the hooked seamless can body in the fitted state, cooling the punch through the can body, in the ascending process of the punch, the surface temperature of the outer surface resin film of the can body A resin-coated metal seamless can body characterized in that the degree of engagement of the can body and the die is reduced and the can body is pulled upward from the inside of the die while the degree is set to be equal to or lower than the glass transition point of the resin. Manufacturing method. The method for producing a resin-coated metal seamless can body according to claim 1, characterized that you pre-heating at least a body wall to 20 ° C. to 80 ° C. of the cup-shaped intermediate material before processing.

Images