JP2003164921A - Production method for resin-coated metal seamless pipe shell - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent a defective drawing molding or ironing molding of a seamless pipe shell by controlling the temperature of a punch by heating, cooling, or keep warming the punch from the outside. <P>SOLUTION: According to a production method for the resin-coated metal seamless pipe shell, a cup-shaped intermediate material is formed by carrying out the drawing process of a resin-coated metal plate that is formed by coating both surfaces of a metal plate with a thermoplastic resin. The intermediate material is then subjected to a re-drawing process, re-drawing and ironing process, or an ironing process to obtain the bottom-attached seamless pipe shell with a flange. Before starting production, or during a no-load running when a continuous production is stopped, the punch is heated from the outside to raise the surface temperature of the punch to make it higher than that of the cup-shaped intermediate material before the process and near the ultimate temperature of the punch during the continuous production. Then, just before starting production or re-starting production, the heating of the punch is stopped, and the punch, which has accumulated heat, is used to produce the seamless pipe shell with the flange. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to redrawing or redrawing a cup-shaped intermediate material obtained by subjecting a metal plate coated on both sides with a thermoplastic resin to a drawing process with a punch and a die. The present invention relates to a method for manufacturing a seamless can body with a collar by processing or ironing.

[0002]

2. Description of the Related Art Generally, metal cans (containers) made of aluminum or steel are roughly classified into three-piece cans and two-piece cans or bottle-type cans according to their shapes. Three-piece cans are called three-piece cans because they consist of a bottom lid, a can body joined by welding or bonding, and a canopy. A two-piece can is called a two-piece can because it has a structure in which a canopy is attached to a can body with an integrated can bottom and two members, a can body and a canopy, are constituent members. It is also called a seamless can because it is seamless. Further, the bottle-shaped can is composed of a side seamless can body having a threaded portion formed at one opening end of the can body, a cap and a bottom lid which are screwed into the threaded portion, and has a glass shape as a whole. It is called a bottle can because it resembles a bottle made of plastic.

In any of these metal cans, a protective layer made of 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 often made of a resin film-coated metal plate in which a resin film is laminated on a metal material, and is subjected to deep drawing or drawing and ironing. In order to obtain a two-piece can body, the amount of deformation or the degree of processing of the material is large, so a high level of molding technology is required.

That is, the merit of the laminated can depends on the organic resin film to be applied, but is excellent in the content resistance, in particular, the flavor and flavor of the content. On the other hand, as a disadvantage, there is a problem in can manufacturing, but since the degree of processing (or the degree of molding) 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 Since it is not possible to secure the quality of the cans, it is necessary to perform a strict quality inspection of the cans, and the product yield is inferior to that of general paint cans.

In particular, the tendency is remarkable in the case of a two-piece type laminated can using a steel material,
The same thing happens with a laminated can of aluminum material. Such a defect of the resin film on the inner surface of the laminated can occurs during the can forming process as described above, and minimizing the defect is an important issue from the viewpoint of quality and product yield.

More specifically, a cup-shaped intermediate material obtained by drawing a metal plate whose both surfaces are coated with a thermoplastic resin is redrawn by a punch and a die and redrawn and ironed or ironed. When manufacturing a bottomed seamless can body, unlike the conventional seamless can manufacturing method that uses a material without a resin coating, there is no washing step in the subsequent process, so a cooling agent ( Coolant) cannot be used. Therefore, the temperature of the punch and the die rises as the number of cans increases immediately after the start of production, but the temperature of the punch rises sharply compared to the die,
Due to the expansion of the punch, the clearance between the punch and the die becomes small, and the wall thickness of the can body becomes thin immediately after the start of manufacturing, or the wall thickness and flange width in the circumferential direction of the can body become uneven. Sometimes. For this reason,
The can body manufactured until the temperature rise of the punch stabilizes needs to be discharged as a defective can out of the system, and the manufacturing efficiency may decrease due to the crushing of the can body, which causes a manufacturing cost increase. Was there.

The above laminated can is also manufactured by redrawing, redrawing, or ironing a cup-shaped intermediate material made of a coated metal plate coated with a thermoplastic resin film as described above. An apparatus configured to control the temperature of a forming tool is known as an apparatus capable of preventing a breakage of the coating resin and a crack of the coating resin in the manufacturing process. This type of device is disclosed in, for example, Japanese Patent Laid-Open No. 1-27892.
No. 1 (Japanese Patent Publication No. 7-57388), Japanese Patent Laid-Open No. 6-
No. 210381, JP-A-7-275961 and the like.

Briefly explaining the inventions described in these publications, the method described in Japanese Patent Laid-Open No. 1-278921 is a method of manufacturing a container in which the temperature of the punch during the process is maintained at a temperature of 50 to 80.degree. Is the way. In addition, JP-A-6-2103
In the method described in Japanese Patent No. 81, hot water flows through the die (or the die and the wrinkle retainer) when a seamless can is manufactured by subjecting a laminated metal plate having polyester films laminated on both sides to redrawing. Then, the hot water is switched to cold water immediately before the start of processing, and the surface temperature of the die facing the wrinkle press (or the wrinkle press facing the die) is maintained at 40 to 100 ° C. during the processing. Furthermore, the invention described in Japanese Patent Laid-Open No. 7-275961 heats the inside of the die, the wrinkle retainer and the punch before the molding operation, switches the heating to cooling immediately before the start of molding, and continues cooling during molding. This is a method for producing a seamless can in which the surface temperature of the die, the wrinkle retainer, and the punch, and the punch surface temperature immediately after extraction are kept within a predetermined temperature range.

[0009]

In any of the above-mentioned conventional inventions, the temperature of the apparatus for producing a seamless can is controlled by controlling the temperature of water flowing through the forming tool or switching the flowing fluid. This is a method of adjusting, and has the following problems.

First, the invention described in Japanese Patent Laid-Open No. 1-278921 (Japanese Patent Publication No. 7-57388) is as follows.
A liquid circuit is created in the punch, and a coolant is passed through the liquid circuit to exchange heat from the inside of the punch to maintain the punch temperature at a predetermined temperature. Therefore, there is a problem that the temperature control reaction by the cooling liquid is slow and it is difficult to control the temperature with high sensitivity. Further, in order to pass the cooling liquid and suppress the temperature rise due to heat generation of the punch, it is necessary to improve the heat exchange efficiency of the liquid and to allow as much cooling liquid as possible to flow into the water flow circuit. Since the water flow circuit is hollow due to its structure, which causes a decrease in strength, considering the strength of the punch, the length of the water flow circuit and the cross-sectional area of the flow path are restricted in space, and the cooling performance is poor. Not always enough,
There is a problem that the temperature distribution of the punch is not uniform.

On the other hand, in the inventions described in JP-A-6-210381 (Japanese Patent No. 2550845) and JP-A No. 7-275961 (Japanese Patent No. 2790072), flow through the die immediately before the start of processing. By switching the hot water being used to cold water, the upper surface temperature of the die facing the wrinkle retainer is maintained at an appropriate temperature (40 to 100 ° C.) and redrawing is performed. Therefore, the above-mentioned JP-A-1-
Similar to the invention of Japanese Patent No. 278921 (Japanese Patent Publication No. 7-57388), there is a problem that it takes time for heat exchange, the cooling reaction to the rapid temperature change of the punch surface is slow, and it is difficult to control the temperature with high sensitivity. Further, when the hot water flowing through the die is switched to cold water, in order to circulate the water for temperature adjustment from the outside of the mold to each forming tool through the die holder, for example, for multiple picking,
In the case of a mold structure that allows multiple molding tools to be attached to a common die holder, the temperature of the die holder itself, which is in a warm state with hot water flowing through immediately before the start of manufacturing, changes its temperature by switching from hot water to cold water. Distortion due to changes easily causes misalignment between the punch attached to the upper die and the die attached to the lower die, which causes variations in the wall thickness of the can body, and breakage. There is a problem that it is easy to do.

Similarly, when switching from hot water to cold water in a die, it is difficult to perform uniform cooling over the entire circumference and distortion occurs in the die, and as a result, the roundness of the die is likely to be impaired. As a result, there is a problem that the wall thickness of the can body becomes uneven and the body is easily broken.

The present invention has been made by paying attention to the above technical problems, and a seamless can with a collar made of a resin-coated metal is subjected to drawing or redrawing and ironing on a cup-shaped intermediate material. An object of the present invention is to provide a method capable of improving the uniformity of the can wall at the beginning of the production, or at the time of resumption after the interruption, and at the same time, preventing defects such as brim breakage during production. Is.

[0014]

In order to achieve the above-mentioned object, the invention of claim 1 is formed by drawing a resin-coated metal plate coated with a thermoplastic resin on both sides of the metal plate. The cup-shaped intermediate material, in the method for producing a resin-coated metal seamless can body to obtain a bottomed seamless can body by redrawing or redrawing ironing or ironing with a punch and a die, the seamless method Before starting the production of the can body or during the idle operation when the continuous production is interrupted, the punch is heated from the outer surface side, the punch surface temperature is higher than the temperature of the cup-shaped intermediate material before processing, and A feature is that the temperature is raised to near the punch reaching temperature, heating of the punch is stopped immediately before the start of production or immediately before the restart of production, and a seamless can body with a collar is produced using the punch in the heat storage state. It is a method of.

That is, according to the first aspect of the invention, in consideration of the temperature change at the time of punch start-up associated with the start of manufacturing, the surface temperature of the punch is heated and raised in advance before the start of continuous manufacturing. By stopping the heating of the punch, it is intended to suppress the generation of defective cans immediately after the start of manufacturing. Therefore, according to the first aspect of the invention, before starting continuous production of the collared seamless can body or during idle operation during production interruption, the punch during idle operation is heated from the outer surface side to reduce the punch surface temperature before processing. The temperature is higher than the temperature of the cup-shaped intermediate material and near the temperature reached by the punch during continuous manufacturing, the heating of the punch is stopped immediately before the start of manufacturing or immediately before the restart of manufacturing, and the punch is stored in the heat storage state. By starting or restarting manufacturing, it is possible to reduce the change in the temperature rise curve of the punch immediately after starting manufacturing or immediately after restarting manufacturing. That is, while the heat is taken from the punch to the cup-shaped intermediate material, the heat generated by the forming process of the can body is supplemented, so that the continuous production is started from the state where the punch is idle, that is, the production is started. There is little change in the temperature of the punch before and after, and it is possible to maintain a temperature that is close to the temperature reached by the punch during continuous manufacturing, so it is possible to reduce the change in punch diameter, and when starting (or restarting) manufacturing. It is possible to reduce the number of defective cans and to reduce the change in the brim length of the seamless can body over the entire circumference, and to prevent the occurrence of brim break during processing.

Moreover, the heat is applied to the entire peripheral surface of the punch retracted from the die during the idle operation almost uniformly. Therefore, the variation in the wall thickness of the metal can body in the circumferential direction of the can body immediately after the start of production is reduced, and it is possible to prevent galling and crushing of the thermoplastic resin film.

In addition, when the interruption of continuous production is short,
Even if the interruption occurs in pieces, the outer peripheral surface of the punch can be rapidly and directly heated from the outer surface side and supplied with heat, so that the responsiveness to temperature change is improved.

In addition to the invention of claim 1, the invention of claim 2 circulates constant temperature water at a constant temperature of 20 ° C to 80 ° C in the punch and the die before continuous production, and It is a method characterized by starting continuous production while maintaining the state.

Therefore, according to the invention of claim 2, 20 ° C.
By circulating a constant temperature water of a constant temperature of -80 ° C inside the punch and the die to heat and keep them warm,
In that state, the punch is further heated from the outside, so even if the environment temperature in which the metal can body forming device is placed is different in summer and winter, it does not depend on that temperature environment and when manufacturing starts (restarts). The temperature difference between the above temperature and the temperature reached by the punch during continuous manufacturing can be made substantially constant, and the heating temperature of the punch during idle operation can be easily controlled.

Further, according to the invention of claim 3, in the invention of claim 1 or 2, during continuous manufacturing, cooling is performed from the outer surface side of the metal can body fitted in the punch in the vicinity of the bottom dead center of the punch. The method is characterized by

Therefore, in the third aspect of the invention, the punch is cooled from the outside of the can body in a state where the punch descends and the can body is subjected to the redrawing process, the redrawing ironing process or the ironing process. Therefore, during continuous manufacturing, at the final stage of the punch advance process, that is, near the bottom dead center of the punch stroke, the can body that has been fitted into the punch is cooled from the outer surface side to be formed and fitted into the punch. It is possible to cool the can body during the process and also to cool the punch through the can body. In the punch return (raising) process, the engagement state of the die is eased to make the collared seamless can body die. In addition to making it easier to pull out from the inside, the surface temperature of the outer resin film can be kept below the glass transition point (Tg) of the resin, so the resin film is softened by the processing heat and the resin is prevented from sticking to the punch surface. Therefore, it is possible to easily strip the flanged seamless can body from the punch and prevent galling of the outer resin film.

The invention of claim 4 is characterized in that, in any of the inventions of claims 1 to 3, at least the body wall of the cup-shaped intermediate material before processing is preheated to 20 ° C to 80 ° C. Is the way.

Therefore, in the invention of claim 4, since the body wall of the cup-shaped intermediate material to be redrawn, redrawn and ironed or ironed is preheated to 20 ° C to 80 ° C, the resin coating Molding can be performed near the glass transition temperature, the can body can be easily stripped from the punch, and the moldability can be improved.

[0024]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail below with reference to specific examples shown in the drawings. First, an example of a seamless can body targeted by the present invention is a can body of a bolt-type can having a cap on the mouth and neck, which is manufactured, for example, through the steps shown in FIG.

As a material for this seamless can body, a resin-coated metal plate having thermoplastic resin laminated on both sides is used. This is punched into a disc shape in a cup forming process to form a blank, and the blank is subjected to a drawing process. To form a cup-shaped intermediate material. 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 bottomed can whose body has a small diameter and is thinned. Form on the body. In that case, bending and stretching may be performed at the same time.

Next, in the top dome molding process,
In order to form the can bottom side of a bottomed cylindrical can body into a mouth neck portion and a shoulder portion, first, in the first step, the can bottom corner portion (the bottom portion and the cylindrical portion in the vicinity of the bottom portion in the above can barrel. ) Is formed on the curved surface of the lower portion of the shoulder having an arcuate vertical cross section, and a small-diameter bottomed cylindrical portion is drawn, and in the second to third steps, drawing is performed multiple times on the can bottom side. As a result, the diameter of the bottomed cylindrical portion is reduced until it becomes almost the same as the diameter of the mouth and neck portion. Further, in the fourth step, the shoulder portion formed following the initial shoulder lower curved surface by repeating such drawing is
Reform into a continuous smooth curved surface. Then, in the fifth step and the sixth step, the bottomed cylindrical portion formed to have substantially the same diameter as that of the mouth / neck portion is subjected to double draw forming.

The lubricant adhering to the body of the can, which has been formed with the mouth-neck portion and the shoulder portion which are not opened on the can bottom side in the above-mentioned top dome forming step, is removed in the next lubricant removing step. In the subsequent trimming step, the open end side of the body opposite to the mouth and neck is trimmed to make the can have 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 with the open end opposite the mouth and neck, and the printing is applied. A clear curable paint (clear paint) for protecting the outer surface of the can is applied to the outer surface of the body as a top coat. This printing and painting process is the same as the printing and painting process for the ordinary cylindrical body of a two-piece can.

The can body on which printing and painting have been completed 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 at a temperature higher than its crystal melting temperature and then cooled to 160 ° C. within 8 seconds to be amorphized. After that, in the screw / curl molding step, first, the tip closing part of the unopened mouth / neck part is trimmed to open the mouth / neck part, and the opening end part is wound outward (or inwardly) to form an annular curl part. Then, a screw for cap screwing is formed on the cylindrical peripheral wall, and then a bead portion is formed below the screw forming portion.

Then, in the neck and flange forming step, neck-in processing and flange processing are sequentially performed on the lower end opening end of the body portion on the side opposite to the mouth and neck portion. The bottle-shaped can body thus obtained is sent to a bottom lid winding process (not shown), and a seamer (a can lid winding machine) is used to separate a bottom lid made of a metal plate from the lower end opening of the body portion. The bottle-shaped can is completed by integrally fixing it to the flange portion formed by the double winding method.

The resin-coated metal plate that can be used in the present invention will now be described. The resin-coated metal plate is not particularly limited, and it may be an aluminum alloy plate or the surface of various metal plating or chemical conversion treatments. Surface-treated steel plates such as treated ultra-thin tin-plated steel plates, nickel-plated steel plates, electrolytic chromic acid-treated steel plates, and zinc-plated steel plates can be used. As the surface treatment, it is desirable to use a metal plate subjected to a surface treatment for the purpose of ensuring adhesion with the thermoplastic polyester resin film.

For example, after forming an ordinary drawn and ironed can
Phosphochromic acid treatment used as a surface treatment for
Zirconium phosphate treatment is applied, but especially can
In the case of high workability with a large degree of wall thickness reduction, phosphoric acid or
Or organic-inorganic composite type of zirconium phosphate and organic resin
Chemical conversion treatment is effective. Specifically, for example,
It is an aluminum alloy plate of 0.24 mm to 0.38 mm.
3004 series, 3 specified by Japanese Industrial Standards (JIS)
Chromium 1 to 40 mg / m on 104 series aluminum alloy ^Two, With
Chromate phosphoric acid treatment or zirconium
4 to 17 mg / m ^TwoZirconium phosphate treatment
Those that have undergone chemical conversion treatment are used.

The steel sheet according to the present invention is, for example, a surface-treated steel sheet having a thickness of 0.15 mm to 0.25 mm,
20 to 2000 mg / on both sides of the steel sheet
nickel plating layer of m ^2, having a chemical conversion coating layer composed mainly of an organic resin of 100 mg / m ² from the 1 mg / m ² as a single-side adhesion amount of C is used as an upper layer. The steel plate before nickel plating and chemical conversion treatment is not particularly limited, and a steel plate normally used as a steel plate for can making is applied.

As the resin film coated on the metal plate, a thermoplastic polyester resin film having good heat resistance and characteristics suitable for use in cans is used. As the polyester resin, for example, polyethylene terephthalate (PET) is used. , Polybutylene terephthalate (PB
T), homopolymers such as polyethylene isophthalate (PEI), copolymers such as copolymer resins of polyethylene terephthalate and polyethylene isophthalate, blends of such homopolymers, blends of homopolymers and copolymers, Examples include blend resins of copolymers.

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 blending ratio thereof. For example, the melting point (Tm) is 200 ° C. A resin film of ~ 260 ° C is applied. Further, the resin-coated metal plate of the present invention, after being laminated, is heated and melted to a temperature not lower than the melting point of the heat-bonded thermoplastic resin film, and then rapidly cooled to a temperature not higher than the glass transition point to be amorphized. Alternatively, 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.

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 described above. 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, and a double action 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 arranged below the die holder 4.

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 so as to hang down. A punch 9 is attached to the lower end of the punch drive shaft 7 for processing the cup-shaped intermediate member 8 made of a resin-coated metal plate to reduce the wall thickness.

The punch 9 is composed of a core material 9a and a sleeve 9b closely fitted to the outer periphery of the core material 9a, and at least the sleeve 9b is made of cemented carbide. A spiral flow path 10 is formed at a boundary portion between the core material 9a and the sleeve 9b. In the flow path 10, a water supply / drainage path 11 formed by penetrating the nose holder 6 and the punch drive shaft 7 is formed. Are in communication. The water supply / drainage channel 11 is connected to a heat source unit (not shown) that circulates and supplies constant temperature water of 20 to 50 ° C., for example.

The outer slide 2 is formed with an opening through which the punch drive shaft 7 and the punch 9 pass, and a piston 12 which moves vertically is provided in the vicinity of the inner circumference of the opening. A pusher pin 13 that moves together with the wrinkle retainer 14 is attached to the tip (lower end) of the pusher pin 13 extending downward. The wrinkle retainer 14 is a hollow cylindrical member having an opening with a diameter larger than that of the punch 9, and the tip (lower end) of the wrinkle retainer 14 presses the flange (flange) of the cup-shaped intermediate member 8. Is configured.

Further, the wrinkle retainer 1 is attached to the intermediate plate 3.
A through hole having a diameter larger than 4 is formed, and a cylindrical wrinkle pressing guide 15 is attached to this through hole. The pusher pin 13 passes through the wrinkle pressing guide 15, and the punch drive shaft 7 passes through an opening formed in the center of the wrinkle pressing guide 15.

A heat source sleeve 16 is attached to the 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 hot air or warm air from the inner surface thereof, a cylindrical body containing a heating wire, a cylindrical body containing an electromagnetic induction coil. It is equipped with a cylindrical body. The heat source sleeve 16 is set to have a length that heats the punch 9 located at the top dead center.

A die 17 for forming a can body together with the punch 9 is attached to the die holder 4 by a holding plate in a state of being loosely inserted, and is held so as to be automatically aligned along the approaching punch 9. ing. The die 17 is a plate-shaped member having an annular shape with an opening for molding processing formed in the center, and the inner diameter of the opening is the punch 9 described above.
The size is such that a predetermined clearance is generated between the outer peripheral surface and More specifically, as shown in FIG.
The opening in the die 17 is, in order from the upper side, a tapered introduction portion 17a that spreads upward, a processing portion 17b that is parallel to the central axis and has a predetermined axial length, and the processing portion 17.
The taper-shaped relief part 1 which spreads to the lower side connected to the lower side of b
7c. Therefore, the portion that comes into contact with the cup-shaped intermediate material 8 that is the workpiece is the processed portion 17b.
And the vicinity thereof, and therefore, the place where heat is generated and the place where the heat is received due to the molding process are limited to a narrow range with respect to the entire die 17.

Further, inside the die 17, there is formed a flow path 18 for flowing a temperature adjusting fluid substantially concentrically with the processed portion 17b, which is formed in the die holder 4 to which the die 17 is attached. The lower surface of the die 17 communicates with the water supply / drainage channel 19 that is present. This channel 18 is, for example, 20 to 20 like the water supply / drainage channel 11 in the punch 9 described above.
It is connected to a heat source section (not shown) so as to circulate and supply constant temperature water of 80 ° C.

Below the die 17, there is provided a cooling sleeve 20 for cooling the punch 9 descending to the bottom dead center from the outer surface side together with the molded body (can body as an intermediate product) fitted therein. It is arranged. This cooling sleeve 20
Is for re-drawing, re-drawing and ironing, or for removing heat generated by the ironing to cool the can body and the punch 9, and as an example, the cooling sleeve 2
It is configured to blow cold air toward the inner peripheral side of 0. 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 the portion of the can body extending downward from the die 17 is lowered. It is set to the length that surrounds the whole.

In FIGS. 2 and 3, reference numeral 21 indicates a knockout, which is arranged vertically below the punch 9 on the same axis as the punch 9.

Next, the method of the present invention using the apparatus constructed as described above will be explained. 20 ° C. to 80 ° C. in the flow path 10 of the punch 9 and the flow path 18 of the die 17 even before the start of the molding process or when the process of interrupting the supply of the cup-shaped intermediate material 8 is stopped (so-called idle operation). The constant temperature water of constant temperature is continuously supplied and heated or kept warm from the inside. Along with this, 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 step, and is a temperature near the punch surface temperature reached when a large number of cup-shaped intermediate materials 8 are continuously processed. is there. As an example, it is 50 ° C to 120 ° C.

Here, the temperature of the cup-shaped intermediate material 8 before processing is generally the ambient temperature in the factory in which the above-mentioned apparatus is installed, or somewhat higher than the ambient temperature due to the residual heat in the previous process. It is the temperature, which can be measured and obtained in advance. Also, during continuous processing (continuous manufacturing)
The surface temperature reached by the punch 9 varies depending on the processing speed, the type of material, the amount of processing, the material of the tool such as the punch 9 and the die 17, etc. Can be kept.

Since the punch 9 is kept warm by the constant temperature water as described above, its temperature hardly changes depending on the season, and therefore the punch 9 by the heat source sleeve 16 is used.
The temperature control can be performed easily and accurately because the presupposed temperature is almost constant. In other words, variations in the surface temperature of the punch 9 due to the season and the ambient temperature are reduced.

In this way, the punch 9 and the wrinkle presser 14 are pulled up to the top dead center in a 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 previous step is set in the die 17. The punch 9 and the wrinkle retainer 14 are lowered on the cup-shaped intermediate material 8 to perform redrawing, redrawing, ironing, or ironing. The operation of the heat source sleeve 16 is performed prior to the lowering of the punch 9. Is stopped, and heating and heat retention of the punch 9 is stopped.

Then, the clutch (not shown) of the press machine is turned on, and the inner slide 1 and the outer slide 2 are lowered. As a result, first, the wrinkle retainer 14 dies the flange of the cup-shaped intermediate member 8 into the die 17.
The cup-shaped intermediate member 8 is set by being sandwiched between the cup-shaped intermediate member 8 and the upper surface. In that state, the outer slide 2 stops descending, but the inner slide 1 further descends, so that the punch 9 attached to the inner slide 1 enters the inside of the cup-shaped intermediate member 8 fixed to the die 17, The can body is formed on the cup-shaped intermediate material 8 together with the die 17.

In this case, the above-mentioned constant temperature water is supplied to the die 17 and is maintained at a predetermined temperature. Therefore, the clearance between the punch 9 and the die 17 at the time of starting or restarting the forming process is maintained at a desired size. Further, the resin coating formed on the inner and outer surfaces of the cup-shaped intermediate member 8 includes the punch 9 and the die 1.
It is molded while being in contact with 7 and being appropriately held within the allowable temperature range of sliding and stretching. Therefore, it is possible to prevent or suppress defects such as variations in the thickness of the body wall, breakage, breakage of the collar, and cracks in the resin coating.

On the other hand, when the processing of the cup-shaped intermediate material 8 set in the die 17 is started, the cooling sleeve 20 is operated, so that the punch 9 lowered to the bottom dead center is fitted into this. Along with the formed body (cup-shaped intermediate member 8), it is cooled from the outer surface side. That is, when the punch 9 performs the thin-wall forming on the cup-shaped intermediate member 8, frictional heat and processing heat due to extension of the material of the cup-shaped intermediate member 8 are generated, but at least a part of the heat is generated in the cooling sleeve. It is robbed by the action of 20. As a result, the cup-shaped intermediate material 8 and the punch 9 are relatively cooled and easily maintained in a predetermined temperature range.

When the punch 9 descends to the bottom dead center in this way, the thin-wall forming is completed, first the punch 9 rises together with the inner slide 1, and then the wrinkle retainer 14 rises, and as the wrinkle retainer 14 rises, Alternatively, as the wrinkle retainer 14 rises, the knockout 23 rises and the can body is pushed upward from the die 17. In this case, since the can body fitted in the punch 9 is cooled by the cooling sleeve 20, the fitting with the die 17 is relaxed, and as a result, the molded body can be easily removed from the die 17. It becomes easy to knock out (release property). Further, since the surface temperature of the resin coating formed on the can body can be set to be equal to or lower than the glass transition point (Tg) of the resin, the resin is softened by the processing heat and adheres 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 caused by galling of the resin coating can be prevented.

The can body as a molded product thus obtained is sent to the next ironing step (not shown).

Since the cup-shaped intermediate material 8 is sent at short time intervals, the above-mentioned forming process of the body wall is repeatedly performed according to the supply speed of the cup-shaped intermediate material 8, and while the processing is continued, Only the constant temperature water is supplied to the punch 9, and heating by the heat source sleeve 16 is not performed.
In the process, if the forming process of the body wall is interrupted due to, for example, the supply of the cup-shaped intermediate material 8 being interrupted, the punch 9
May be in a so-called idle operation state in which the punch simply moves up and down, or the clutch of the press machine is turned off to stop the punch 9 at the top dead center. In that case, after the timer, the heat source sleeve is timed. The punch 9 is heated and kept warm by 16 to prepare for the restart of the next molding process.

Therefore, in the above method according to the invention,
Before the punch 9 starts the substantial forming process of the cup-shaped intermediate member 8, the temperature of the punch 9 is set to a temperature higher than the temperature of the cup-shaped intermediate member 8 and near the ultimate temperature during the continuous forming process. Since the setting is made, the clearance between the punch 9 and the die 17 at the time of starting or restarting the forming process has a desired size, and relative misalignment is avoided, so that the thickness of the body wall is reduced. Molding defects such as unevenness, breakage, rupture or cracks in the collar are eliminated. Also,
Since the temperature of the resin coating provided on the surface of the cup-shaped intermediate member 8 can be set to a temperature suitable for processing, it is possible to prevent the occurrence of defects such as cracks and breaks in the resin coating. That is, since the defective product generation rate at the time of starting or resuming the molding process can be reduced, the material yield or the productivity can be improved.

Further, although processing heat is generated due to the forming process, when the punch 9 descends to the bottom dead center, the punch 9 is cooled by the cooling sleeve 20 together with the can body fitted around the outer periphery thereof. , At least a part of the processing heat 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 outer circumferential surface of the punch 9 uniformly from the outer surface side as described above, the responsiveness of the temperature control is good and the temperature variation is high. Is less.

The results of experiments conducted by the present inventors are shown in FIGS. 5 and 6. The molding process used for the measurement was performed using a thermoreversible polyester resin film-coated aluminum alloy plate (0.12 mm) with a diameter of 1 mm.
A process of redrawing and ironing a cup-shaped intermediate material with a height of 48 mm and an outer diameter of 100 mm obtained by drawing a 70 mm blank into a bottomed cylindrical can body with a height of 171.5 mm and an outer diameter of 65.9 mm. Is.

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 shows the example of the present invention, and the broken line does not heat from the outer surface side by the heat source sleeve 16. A conventional example is shown. This Figure 5
As is clear from the measurement results shown in (1), in the method according to the present invention, the punch temperature is maintained at about the temperature during continuous molding from the beginning of molding. Therefore, it is possible to suppress or avoid defective molding due to temperature conditions such as a temperature difference from the die 17 and a temperature change of the punch 9.

FIG. 6 is a diagram showing the results of measurement of changes in the can body wall thickness. An example in which a sleeve for induction heating is used as the heat source sleeve 16 and a band heater with a built-in heating wire is used. The measurement results of the above example and a conventional example in which heating by the heat source sleeve 16 is not performed are 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 redrawing and ironing.

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 which is a molding target is controlled. May be. For example, the temperature of at least the body wall of the cup-shaped intermediate member 8 is set to 20 ° C. to 80 ° C. before the start of processing.
It is preferable to heat and keep warm. By doing so, the lubricity of the resin coating formed on the surface of the resin becomes good, and since the molding is performed near the glass transition temperature of the resin, the moldability becomes good.

Further, in the above specific example, an example of performing redrawing and ironing forming is described, but the present invention is not limited to the above specific example, and any one of redrawing, stretch forming and ironing forming can be performed. Can also be applied. Further, the heat source output of the band heater and the induction heating coil can be controlled so as to be appropriately changed depending on the material of the punch and the distance and the length between the heat source sleeve and the punch.

[0062]

As described above, according to the present invention, there is little change in the temperature of the punch during the start of continuous production from the idle operation state of the punch, that is, before and after the start of production, and the punch during continuous production is reduced. Since it is possible to maintain a temperature close to the reached temperature of the punch, it is possible to reduce changes in the outer diameter of the punch, reduce the number of defective cans when starting from the start (or restart) of production, and at the same time, the collar of the seamless can body. Reduces the change in length over the entire circumference,
It is possible to prevent the brim from breaking during processing. Moreover, since the entire peripheral surface of the punch retracted from the die during the idle operation is heated by heating it almost uniformly, the variation in the wall thickness in the circumferential direction of the can body of the metal can body immediately after the start of manufacturing is reduced. It is possible to prevent galling and breakage of the thermoplastic resin film. In addition, even if the interruption of the continuous production is short, or even if the interruption occurs in pieces, the outer peripheral surface of the punch can be heated quickly and directly from the outer surface side, so that it is responsive to temperature changes. Get better

Further, according to the invention of claim 2, the punch and the die are heated and kept warm, and in that state, the punch is further heated from the outer surface side. Therefore, the environmental temperature where the molding apparatus is placed is summer. Even if the temperature differs between winter and winter, the temperature difference between the temperature at the start of production (restart) and the temperature reached by the punch during continuous production can be made almost constant regardless of the temperature environment, and the punch during idle operation can be It becomes easier to control the heating temperature.

Further, according to the third aspect of the present invention, during the continuous production, the can barrel in the state of being fitted to the punch is placed on the outer surface side in the final stage of the punch forward step, that is, near the bottom dead center of the punch stroke. It is possible to cool the can body that has been molded and fitted into the punch by cooling from above, and it is also possible to cool the punch through the can body. In the punch returning (raising) process, the die is engaged. It eases the condition and makes it easier to pull the collared seamless can body out of the die, and since the surface temperature of the outer resin film can be kept below the glass transition point (Tg) of the resin, the resin film softens due to the processing heat. It is possible to prevent the resin from sticking to the surface of the punch, making it easier to strip the seamless can body with a collar from the punch and preventing galling of the outer resin film. The ability.

Further, according to the invention of claim 4, since the body wall of the cup-shaped intermediate material subjected to the drawing process, the redrawing ironing process or the ironing process is preheated to 20 ° C to 80 ° C, the resin is Molding can be performed near the glass transition temperature of the coating, the moldability can be improved, and the mold-releasing property can be improved by keeping the temperature of the cup-shaped intermediate material constant.

[Brief description of drawings]

FIG. 1 is a process chart schematically showing an example of a forming process of a seamless can body targeted by the present invention.

FIG. 2 is a sectional perspective view schematically showing an example of an apparatus used in the can body forming step.

3 is a schematic cross-sectional side view of the device shown in FIG.

FIG. 4 is an enlarged sectional view showing a molding portion of a die.

FIG. 5 is a diagram showing measurement results of changes in punch temperature in comparison between the example of the present invention and the conventional example.

FIG. 6 is a diagram showing measurement results of changes in can body wall thickness, comparing the present invention example with a conventional example.

[Explanation of symbols]

8 ... Cup-shaped intermediate material, 9 ... Punch, 10, 18 ... Flow path, 16 ... Cooling sleeve, 17 ... Die.

─────────────────────────────────────────────────── ───

[Procedure amendment]

[Submission date] December 7, 2001 (2001.12.
7)

[Procedure Amendment 1]

[Document name to be corrected] Drawing

[Name of item to be corrected] Figure 5

[Correction method] Change

[Correction content]

[Figure 5]

[Procedure Amendment 2]

[Document name to be corrected] Drawing

[Name of item to be corrected] Figure 6

[Correction method] Change

[Correction content]

[Figure 6]

Claims (4)

[Claims] 1. A cup-shaped intermediate material obtained by drawing a resin-coated metal plate coated with a thermoplastic resin on both sides of a metal plate, and redrawing or redrawing ironing or ironing with a punch and a die. In the method for producing a resin-coated metal seamless can barrel to obtain a bottomed seamless can barrel with a collar, before the start of production of the seamless can or during idle operation during which continuous production is interrupted, the punch is attached to the outer surface. Heating from the side to raise the surface temperature of the punch to a temperature higher than the temperature of the cup-shaped intermediate material before processing and near the temperature reached by the punch during continuous manufacturing, and heat the punch immediately before or immediately after the start of manufacturing. A method for producing a resin-coated metal seamless can body, characterized by producing a seamless can body with a collar using a punch in a heat storage state. 2. Before continuous production, constant temperature water having a constant temperature of 20 ° C. to 80 ° C. is circulated in the punch or the die, and continuous production is started while maintaining this state. Item 2. A method for producing a resin-coated metal seamless can body according to Item 1. 3. The resin coating according to claim 1, wherein during continuous production, cooling is performed from the outer surface side of the metal can body fitted in the punch near the bottom dead center of the punch. Manufacturing method of metal seamless can body. 4. The resin-coated metal seamless can body according to any one of claims 1 to 3, wherein at least the body wall of the cup-shaped intermediate material before processing is preheated to 20 ° C to 80 ° C. Production method.