JP2007245209A - Method and apparatus for manufacturing resin coated seamless can - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent the quality deterioration of a product due to dew condensation by preventing the generation of the dew condensation by the following even when the temperature of a cooling fluid for cooling a punch from the inside during forming so as to deal with can-making at high speed is set lower in the manufacture of a resin coated seamless can which is formed into a seamless can from a cup body through ironing in the dry state. <P>SOLUTION: The cooling fluid is flowed through the inside of a punch 6 by running through the inside of a piston shaft 7 to the piston shaft 7 on the front end side of which the punch 6 is mounted and which is extended in the moving direction of a punch 6 and also drying air is blown toward the surface of the piston shaft 7 with an air blowing device 10 during forming by which the cup body 2 is made into the seamless can through ironing with the punch 6 and a die 5 in the dry state. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention is a resin produced through a cup body (cup-shaped intermediate molded product) from a resin-coated metal plate in which the surface of a steel-based or aluminum-based metal plate (at least the surface that becomes the outer surface of the can) is coated with a resin layer. With regard to coated seamless cans, in particular, a cup body integrally formed from a resin-coated metal plate is formed into a seamless can through a squeezing and ironing process in a dry state without using a cooling lubricant (coolant). The present invention relates to a method for producing such a resin-coated seamless can and an apparatus for carrying out the method.

  As a steel or aluminum seamless can (a two-piece can body) used as a container for various beverages and foods, in recent years, the surface of the metal plate (at least the outer surface of the can) is a thermoplastic resin. In many cases, resin-coated seamless cans manufactured from resin-coated metal plates coated with a layer are used. In the manufacture of such resin-coated seamless cans, the surface of the resin-coated metal plate (the top of the resin layer) is used. ) By applying a lubricant in advance, and spraying a cooling lubricant called coolant when forming the cup body of an intermediate molded product into a seamless can of elongated bottomed cylindrical shape by drawing and ironing After forming in a dry state, the lubricant applied to the resin-coated metal plate and adhering to the can body is volatilized by heating and removed from the seamless can. It is conventional.

  According to such a can-making method in a dry state of a resin-coated seamless can, it becomes possible to omit the degreasing, washing and chemical conversion treatment steps and the waste water treatment equipment for the conventional seamless can making. In addition, the cost of fuel, electricity, water, and other secondary materials and equipment costs consumed in this treatment process can be greatly reduced, and the environmental impact is small. It can be said that it is a desirable method for making cans at present. However, with respect to such a can manufacturing method in a dry state, there is no practical problem in the case of can manufacturing at a relatively low speed of about 100 cans / min to 150 cans / min. In the case of high-speed can manufacturing such as seamless can manufacturing using), the application becomes difficult.

  That is, when making a resin-coated seamless can at high speed in a dry state, the temperature of the can greatly increases due to molding heat generated by friction between the can and the die during ironing by drawing ironing or ironing. Thus, on the outer surface side of the can, the resin layer is softened so that the properties of the surface of the resin layer become non-uniform, the processing force acting on the surface of the resin layer varies, and the resin layer is scraped. As a result, a molding defect called so-called build-up occurs in which streaky scratches occur on the can surface, whereas on the inner surface side of the can, the resin layer is softened so that the resin layer is welded to the punch, As a result, the frictional force between the punch and the punch increases, and there is a risk that a so-called strip defect in which the punch cannot be removed from the can frequently occurs.

In order to solve such a problem, it has been conventionally proposed to suppress an increase in the can temperature during the ironing process by allowing a cooling fluid to flow inside the punch. Specifically, in the case where a seamless can is continuously made at high speed from a cup body formed by drawing a resin-coated aluminum plate, “the cooling liquid is allowed to flow through the punch and the punch surface temperature is 35 to 100 ° C. The ironing process is performed while maintaining an appropriate temperature within the range of "A.", and the seamless can is produced from a metal cup whose inner and outer surfaces are coated with an organic coating. In the case, “through-holes are provided in the die, punch holder and punch, and hot water (preferably about 40 to 85 ° C.) is cooled to cold water (about 5 to 30 ° C., more preferably about 12 to 18 ° C. immediately before the start of molding. ”And continue to flow through cold water during molding” is disclosed in Patent Document 2 below.
JP 2002-178048 A JP-A-7-275961

  By the way, according to the conventionally known resin-coated seamless can manufacturing method in which the cooling fluid is allowed to flow through the inside of the punch during the molding as described above, in any case, the molding is performed by the cooling fluid to be flowed into the inside of the punch. Suppressing the rise of the can temperature in the inside (during ironing) and suppressing the softening of the resin layer coated on the can surface prevents the occurrence of molding defects called build-up on the outer surface side of the can. In addition, the punching failure (strip failure) on the inner surface side of the can is prevented.

  In addition, when a resin-coated seamless can is produced in a dry state by a conventionally known method as described above, the temperature of the lubricant applied to the surface of the resin-coated metal plate and attached to the surface of the can is low. Since the dynamic friction coefficient increases, the punch etc. needs to be cooled in the state where a lot of molding heat is generated by ironing after the start of molding. In the state where molding heat is not generated so much, the punch needs to be heated in order to prevent the temperature of the lubricant on the surface of the can from being too low. In addition, when cans are made continuously from the beginning of molding, the molding heat will gradually increase and the punch will thermally expand until the temperature reaches a certain temperature, which changes the molding dimensions of the seamless can. In addition, it is necessary to preheat the punch before the start of molding.

  In this regard, in the method disclosed in Patent Document 1, “a heating liquid kept at an appropriate temperature (B ° C.) within a range of 35 to 70 ° C. is circulated in the punch before continuous canning. The liquid circulated in the punch immediately before or immediately after the start of continuous can making is switched to a cooling liquid at an appropriate temperature (C ° C.) within the range of 15 to 70 ° C. and below B ° C. In other words, during the molding, “the ironing process is performed while maintaining the surface temperature of the punch at an appropriate temperature (A ° C.) within the range of 35 to 100 ° C.”.

  Further, in the method disclosed in Patent Document 2, “for example, hot water (preferably about 40 to 85 ° C.) is allowed to flow through the die before the molding operation,” “at the start of molding, hot water is allowed to flow in advance. “The surface temperatures Td, Ts and Tp of the punch presser and punch are kept at 10 ° C. or higher.” And “When the molding is started, the surface temperatures Td, Ts and Tp rise due to processing heat and frictional heat. "In order to suppress this temperature rise and make the surface temperatures Td, Ts, and Tp Tg + 50 ° C or less, cold water is allowed to flow through the dies, punch holders, and punches." , The hot water is switched to, for example, cold water (about 5 to 30 ° C., more preferably about 12 to 18 ° C.), and the cold water continues to flow through during molding.

  However, according to the conventionally known methods as described above, in any case, since the temperature is once heated and then cooled at the start of molding, the heat generation amount per unit time is particularly high. When applied to cans (150 cans / min or more), it becomes difficult to maintain the surface temperature of punches or the like at a predetermined temperature (for example, within a range of 35 to 100 ° C. or Tg + 50 ° C. or less). It becomes difficult to suppress the rise in can temperature.

  On the other hand, even in the case of high-speed can manufacturing where the calorific value per unit time is large, in order to maintain the surface temperature of the punch during molding at a temperature below a predetermined temperature, Although it is conceivable that the temperature of the cooling fluid that flows into the pipe is cooled to, for example, 5 ° C. or lower, which is lower than 20 ° C., in such a case, although the increase in the can temperature during canning can be suppressed, The present inventors have found that the following problems occur.

  That is, a cooling fluid (cooling water or the like) that flows through the inside of the punch in order to suppress an increase in the surface temperature of the punch is supplied through the inside of the piston shaft on which the punch is mounted. As the fluid passes through the inside of the piston shaft, the lower the temperature of the fluid, the lower the surface temperature of the piston shaft. As a result, the surface temperature of the piston shaft is lower than the dew point temperature of the atmosphere around the piston shaft. Then, condensation will occur on the surface of the piston shaft. It has been found from various experiments that this condensation is likely to occur in summer when the temperature around the can manufacturing apparatus exceeds 25 ° C.

  If dew condensation occurs on the surface of the piston shaft on which the punch is mounted in such a manner, this dew condensation is scattered with the reciprocation of the piston shaft, and the scattered dew condensation is even a little on the surface of the can or punch being molded. It has been found that the adhesion causes non-uniform dynamic friction resistance at the time of molding or locally changes the temperature distribution of the can to cause a so-called galling phenomenon in the resin layer covering the surface of the can. Also, it may be brought to the side of the die including dirt on the machine body or dirt in the air, and if it adheres to the surface of the can that is fed into the die, the die and punch It has been found that there is a possibility that the resin layer may be damaged by dirt attached along with condensation during the ironing process. Furthermore, it is conceivable that the condensation that is scattered during idling may adhere to the can formed afterwards through a conveying device such as a brush guide, and the appearance of the appearance is caused by whitening in the portion where condensation has adhered in the subsequent heat treatment process. It has been found that there are problems such as lowering.

  The present invention has an object to solve the above-described problems. Specifically, in the production of a resin-coated seamless can that is molded from a cup body into a seamless can through ironing in a dry state, the present invention can be performed at high speed. Even if the temperature of the cooling fluid that cools the punch from the inside during molding is set to be lower so that it can be used for the production of cans, it prevents condensation from forming, so that the quality of the product resulting from the condensation It is an object to be able to prevent the decrease.

  In order to solve the above-mentioned problems, the present invention seamlessly applies a cup body integrally formed from a resin-coated metal plate, at least the outer surface of which can be coated with a resin layer, through ironing in a dry state. In the manufacturing method of resin-coated seamless cans that can be molded into cans, a punch is mounted on the front end side in the direction of punch movement during molding to make the cup body seamless after ironing with a punch and die in a dry state. A cooling fluid is caused to flow through the inside of the punch through the inside of the piston shaft with respect to the extending piston shaft, and air for drying is blown toward the surface of the piston shaft.

  As already mentioned, in order to suppress the surface temperature of the molding punch from rising due to high-speed can manufacturing, when the temperature of the cooling fluid that cools the punch from the inside during molding is set lower, The cooling fluid that flows through the inside of the punch passes through the inside of the piston shaft on which the punch is mounted. The lower the temperature of the fluid, the lower the surface temperature of the piston shaft. Condensation will occur, but according to the method for producing a resin-coated seamless can of the present invention as described above, air for drying is blown toward the surface of the piston shaft during molding. Such condensation can be prevented from occurring.

  As a result, during molding by ironing, a low-temperature cooling fluid is allowed to flow through the inside of the punch, thereby sufficiently suppressing an increase in can temperature and suppressing softening of the resin layer coated on the can surface. It is possible to prevent the occurrence of molding defects called build-up on the outer surface side of the can and the occurrence of punch removal failure (strip failure) on the inner surface side of the can, and the cooling fluid at such a low temperature can be used as a piston. Despite the flow through the shaft to the inside of the punch, no condensation occurs on the surface of the piston shaft, thus preventing product quality deterioration (resin layer galling phenomenon on the can surface) due to the condensation. Can do.

  In the production of resin-coated seamless cans that are molded from cup bodies into seamless cans through ironing in a dry state, the temperature of the cooling fluid that cools the punch from the inside during molding is increased so that it can be made at high speed. The following example specifically shows the purpose of making it possible to prevent deterioration of product quality due to condensation by preventing condensation from occurring even when set to a low value. Production of a resin-coated seamless can that forms a cup body integrally formed from a resin-coated metal plate, at least the outer surface of which can be coated with a resin layer, through ironing in a dry state In the method, the punch is mounted on the front end side during molding to make the cup body a seamless can through ironing with a punch and a die in the dry state. The piston axis extending in a direction, causes flow through the fluid for cooling the interior of the punch through the interior of the piston shaft, is realized by the fact that blowing air for drying toward the surface of the piston shaft.

Regarding an embodiment of the method and apparatus for producing the resin-coated seamless can of the present invention, first, an apparatus for carrying out the method of the present invention will be described.
The manufacturing apparatus according to the present embodiment is a horizontal body maker that forms a cup body into an elongated bottomed cylindrical seamless can. As shown in FIG. 1, a dormer 3 and a stripper are formed in the same manner as a conventionally known body maker. 4 and a plurality of (three) dies 5 (5a, 5b, 5c) are provided, and the punch 6 reciprocates in the axial direction (piston motion) so as to pass inside the dies 5a, 5b, 5c. Is provided.

  A cup body 2 integrally formed from a resin-coated metal plate by such a manufacturing apparatus 1 is ironed by a punch 6 and dies 5 (5a, 5b, 5c) in a dry state without using a cooling lubricant (coolant). Is formed into a bottomed cylindrical long and slender seamless can whose body is thinly stretched, and then removed from the punch 6 by the stripper 4 when the punch 6 is pulled back. In addition, the seamless can thus formed is transported to the next process, where it is finalized as a final can product by applying inner surface coating, outer surface printing / coating, neck / flange molding, etc. as appropriate. The

  In the seamless can manufacturing apparatus (body maker) 1 as described above, each of the dice 5a, 5b, 5c has a flow path for allowing a fluid at a constant temperature (water in this embodiment) to flow therethrough. The water that is formed in an annular shape and is supplied from a supply device (not shown) is adjusted to a predetermined temperature by the temperature controller 11 and then flows into the flow paths in the dies 5a, 5b, and 5c. After passing through the die, it flows out of the die. That is, the water flowing through the dice 5 circulates inside the dice 5 a, 5 b, 5 c through the circulation path provided with the temperature controller 11.

  The punch 6 that reciprocates (piston motion) in the axial direction so as to pass through the inside of the die 5 (5a, 5b, 5c) is integrated with the front end side (front end side) of the piston shaft 7 extending in the axial direction of the punch 6. It is attached to. The piston shaft 7 serves as a ram for reciprocating the punch 6 in the axial direction, and the piston shaft 7, also called a ram, receives an impact load. In general, the surface does not need to be smoother than the punch 6 and is generally ground to a finished surface of about 0.8 s.

  The rear end side (base end side) of the piston shaft 7 on which the punch 6 is mounted on the front end side is fixed to a reciprocating movement table 8, and this reciprocating movement table (carriage) 8 is not shown, A state of being guided between the pair of slide rails when the power from the driving means (not shown) is transmitted through the connecting rod 9 and is disposed between the pair of slide rails fixed on the table and facing each other. Thus, it is reciprocated in the axial direction of the piston shaft 7.

  As shown in FIG. 6, the punch 6 attached to the front end side of the piston shaft 7 is fitted and inserted into a support cylinder portion 7 a formed integrally with the front end portion of the piston shaft 7. Double spiral grooves 7b and 7c are formed on the surface, and water flows through the inside of the punch 6 between the support cylinder portion 7a of the piston shaft 7 and the punch 6 by the grooves 7b and 7c. As a flow path for the purpose, a spiral flow path 7b in which water flows from the root side to the front end side of the punch 6 and a spiral flow path 7c in which water flows from the front end side to the root side are a double helix. It is formed in a shape. With respect to the flow paths 7 b and 7 c inside the punch 6, a flow path 7 d for feeding water into the inside of the punch 6 and a flow path for returning water from the inside of the punch 6 inside the piston shaft 7. 7d are formed.

  Although not shown, an air blowing hole for blowing air to the inner surface of the bottom of the can is formed in the shaft center of the support cylinder portion 7a so that the molded can can be easily separated from the punch 6. The air blown out from the air blowing hole is supplied through the piston shaft 7 and is blown out from the tip of the punch 6 constantly or intermittently.

  As for the water supplied to the inside of the punch 6 through the inside of the piston shaft 7, the water supplied from the supply device (not shown) is converted into the temperature controller 12 or the temperature controller by the switching device 14 as shown in FIG. In a state where one of the machines 13 is selected, the temperature is adjusted to a predetermined temperature by the temperature controller (12 or 13) and then introduced into the flow path 7d of the piston shaft 7 via the booster 15. Then, the water supplied from the flow path 7d of the piston shaft 7 to the inside of the punch 6 flows through the inside of the punch 6 (double spiral flow paths 7b and 7c), and then the flow path e of the piston shaft 7 To flow out of the flow path e of the piston shaft 7. That is, the water flowing through the punch 6 circulates inside the punch 6 and the piston shaft 7 through a circulation path including the temperature controller (12 or 13), the switching device 14, and the booster 15.

  As shown in FIG. 1, the piston shaft 7 has a flow path (feed flow path 7 d and return flow path 7 e) through which water flows through the punch 6. An air blowing device 10 for blowing drying air toward the surface is provided. Although not shown, the air blowing device 10 is installed in a state of being fixed on the machine base. The device 10 is supplied with dry air from an air supply device (not shown) through a heating / drying device 16. Is supplied.

  As shown in FIGS. 2 and 3, the air blowing device 10 for blowing air for drying onto the surface of the piston shaft 7 surrounds the surface of the piston shaft 7 with a predetermined distance from the surface of the piston shaft 7. Such a tunnel-like inner wall surface 10a is formed. In addition, about the space | interval of the inner wall surface 10a of the air spraying apparatus 10 and the surface of the piston shaft 7, it sets so that it may become the range of 0.3-2 mm, in order to suppress the increase in the consumption of the air sprayed.

  An air channel 10b for flowing the supplied air is formed in the air blowing device 10 along the tunnel-shaped inner wall surface 10a, and the air supplied to the air channel 10b is supplied to the air channel 10b. In order to blow out toward the surface of the piston shaft 7, a plurality of air blowing holes 10c are opened in the tunnel-shaped inner wall surface 10a so as to communicate the air flow path 10b with the outside.

  With respect to the air blowing direction from each air blowing hole 10 c, in this embodiment, the blown air is between the surface of the piston shaft 7 and the inner wall surface 10 a of the air blowing device 10. As shown in FIG. 2, it is inclined at a constant angle with respect to the surface of the piston shaft 7 as seen from the axial direction of the piston shaft 7 so as to flow along the circumferential direction of the piston shaft 7 and flow out in the direction opposite to the die 5 side. In addition, as shown in FIG. 3, the punch 6 is inclined in the backward direction. Specifically, the air blowing direction from the air blowing hole 10c is uniformly inclined in the range of 10 to 60 degrees with respect to the surface of the piston shaft 7 when viewed from the axial direction of the piston shaft 7, and Inclined in the range of 30 to 70 degrees toward the retreat direction of the punch 6.

  As described above, the air blowing direction of the air blowing hole 10 c is uniformly inclined with respect to the surface of the piston shaft 7, thereby allowing each air between the inner wall surface 10 a of the air blowing device 10 and the surface of the piston shaft 7. Since the air blown out from the blowing hole 10c flows in a certain direction along the circumferential direction of the piston shaft 7, the air from the adjacent air blowing holes 10c does not cancel out the momentum between the piston shafts 7 Air can be efficiently flowed, and the entire surface of the piston shaft 7 can be dried economically from the viewpoint of air consumption.

  In the present embodiment, the inner wall surface 10a of the air blowing device 10 in which the air blowing hole 10c is opened as described above, in the present embodiment, as shown in FIG. 4 or 5, the front side close to the die 5 side and the side of the die 5 It is divided into two places on the rear side away from the center. About the installation position of the inner wall surface 10a of this air blowing device 10, that is, the installation position of the air blowing hole 10c for blowing out air, it is desirable to install it separately in the front and rear along the axial direction of the piston shaft 7, thereby The entire surface of the piston shaft 7 during the reciprocating movement can be dried without unevenness.

  For the position of the front inner wall surface 10a (air blowing hole 10c) close to the die 5 side, as shown in FIG. 4, with the piston shaft 7 moving forward and backward in the axial direction at a constant stroke being in the most retracted state, It is preferable to provide at a position corresponding to the edge portion 2a of the can punched by the punch 6 or slightly on the side of the die 5 from the position. That is, metal powder at the time of can making tends to accumulate on the surface of the punch 6 corresponding to the edge portion 2a of the can. By blowing air onto this portion, the surface of the piston shaft 7 is dried and air is blown out. Combined with the fact that the direction is inclined toward the retreat direction of the punch 6, the metal powder deposited on the edge portion 2 a of the can is removed to the rear of the piston shaft 7 and brought to the die 5 side. Can be prevented.

  As for the position of the rear inner wall surface 10a (air blowing hole 10c) away from the die 5, as shown in FIG. 5, the piston shaft 7 that moves forward and backward in the axial direction with a constant stroke is the most advanced. In this state, it is preferably provided in the vicinity of a position corresponding to the rear end portion of the piston shaft 7 (portion serving as a water supply port at the root portion). In other words, this part is a part where cooling water is introduced during molding, and it is away from the molding part that generates heat and is likely to cause condensation, and air is also blown onto this part. Therefore, the surface of the piston shaft 7 can be efficiently dried as a whole, and the piston shaft 7 is driven in combination with the fact that the air blowing direction is inclined toward the retreat direction of the punch 6. It is possible to prevent oil and dust from the reciprocating platform 8 side from being brought into the molding part on the die 5 side.

The manufacturing apparatus 1 of the present embodiment has been described above. Next, a manufacturing method of the present embodiment that is performed using such a manufacturing apparatus 1 will be described.
In the manufacturing method of the present embodiment, the manufacturing apparatus 1 as described above is used, and the ironing process in the dry state is performed without spraying the coolant (cooling lubricant) to the outer surface side of the can during the ironing process. When the seamless can is manufactured, the inside of the die 5 and the punch 6 is cooled so as to be maintained at a temperature of 120 ° C. or less with water for cooling, so that the surface temperature of the can is the resin layer covering the can. The glass transition point (Tg) of the thermoplastic resin is kept at 30 ° C. or lower.

  That is, in a thermoplastic resin used as a resin layer of a resin-coated seamless can, softening starts at a temperature near the glass transition point (Tg), and the higher the temperature, the more the softening of the resin proceeds. When the temperature exceeds (Tg) + 30 ° C., the resin is softened to such an extent that defects on the can can be caused. In particular, as the can-making speed increases, the load applied to the material at the time of can-making increases, and in addition, the amount of heat generation increases, (Tg) + 30 ° C is easily exceeded, and the resin softens more, so-called galling phenomenon occurs. In order to maintain the soundness of the coating resin layer, it is necessary to make a can at the lowest possible temperature.

  Therefore, considering the temperature range of the glass transition point (Tg) of thermoplastic resins (thermoplastic polyester, etc.) currently widely used as a material for seamless cans, cans are made at high speed (150 cans / min or more) However, it is necessary to keep the surface temperature of the can at 120 ° C. or lower (preferably 100 ° C. or lower), so that the die 5 and the punch 6 are cooled from the inside and maintained at a temperature of 120 ° C. or lower as described above. I have to.

  In such cooling of the die 5 and the punch 6, the melting point of the lubricant applied to the surface of the resin-coated metal plate and adhering to the surface of the can body (cup body) at the time of starting can-making is less than the melting point. When cooled down, the lubricant solidifies and accumulates on the die and adheres to the molded seamless can, which may cause molding defects. On the other hand, after the start of can making, molding heat is generated due to the molding of seamless cans, and this heat is absorbed by the die, punch and can, respectively, to raise their temperature. In order not to raise the temperature of the can, it is necessary to absorb molding heat as much as possible by the cooling water flowing through the inside of the die and the punch.

  The molding heat generated during the can manufacturing is mainly due to the friction heat generated by the friction between the die and the can and the processing heat generated by deforming the can through the molding. The contact area between the can and the can is very small. Therefore, the amount of heat transferred to the die is small, whereas the contact area between the punch and can in the can is large, and the amount of heat transferred to the punch is large. Particularly during high-speed can manufacturing), in order to effectively suppress the temperature rise of the can, it is necessary to increase the amount of heat absorbed from the punch (the amount of cooling of the punch).

  Therefore, in this embodiment, the water supplied to the inside of the die 5 with the temperature adjusted by the temperature controller 11 is set to 30 to 35 ° C. (for example, 30 ° C.) higher than the melting point of the lubricant. Water is always supplied at a constant temperature. On the other hand, with respect to the water supplied to the inside of the punch 6 through the piston shaft 7, the water from the temperature controller 12 is removed from the lubricant so that the temperature is not lower than the melting point of the lubricant at the start of can making. From the state of being supplied as 30 to 35 ° C. (for example, 30 ° C.) higher than the melting point, immediately before or just after the start of can making, the water from the temperature controller 12 is supplied from the temperature controller 12 by the switching device 14. By switching to, cold water of 20 ° C. or lower (for example, 10 ° C.) is supplied from the temperature controller 13.

  As described above, the water supplied to the inside of the punch 6 through the piston shaft 7 immediately before or after the start of the can making is from 30 to 35 ° C. (for example, 30 ° C.) to 20 ° C. or less (for example, 10 ° C.). By switching to, the solidification of the lubricant at the start of can making does not lead to poor molding of the can, and the can starts at a substantially constant height from the can at the beginning of molding. Further, the temperature of the punch can be controlled, and the can 6 can be effectively suppressed by efficiently cooling the punch 6 with cold water of 20 ° C. or less (for example, 10 ° C.) during can making. That is, even when producing cans at a high speed (150 cans / min or more), the die 5 and the punch 6 can be maintained at a temperature of 120 ° C. or less (preferably 100 ° C. or less), and the surface temperature of the cans is 120 ° C. or less. (Preferably 100 ° C. or less).

  However, when cold water having a low temperature is supplied to the inside of the punch 6 during the can making as described above, there is no problem in the portion of the punch 6 that is heated by the molding heat, but the water supplied to the punch 6 is passed through. In the portion of the piston shaft 7, the surface temperature of the piston shaft 7 is greatly reduced by passing the inside of the piston shaft 7, while the cold water having a low temperature hardly receives molding heat, and as a result, When the surface temperature of the piston shaft 7 becomes lower than the dew point temperature of the atmosphere around the piston shaft 7, dew condensation occurs on the surface of the piston shaft 7.

  When condensation occurs on the surface of the piston shaft 7 to which the punch 6 is mounted as described above, the condensation is scattered as the piston shaft 7 is reciprocated as described above, and the scattered condensation is formed during molding. If even a small amount adheres to the surface of the can or punch, the so-called galling phenomenon is caused in the resin layer covering the surface of the can by making the dynamic friction resistance during molding non-uniform or by changing the temperature distribution of the can locally. generate. In addition, when the machine body is contaminated with dirt in the air and brought into the side of the die 5 and adheres to the surface of the forming can supplied to the inside of the die 5, the die 5 When the ironing process is performed with the punch 6, the resin layer is damaged by dirt adhering together with dew condensation. In addition, if the condensation that has scattered during idling adheres to the can that is subsequently formed via a conveying device such as a brush guide, whitening occurs in the portion where the condensation has adhered in the subsequent heat treatment process, thereby improving the appearance. If a problem such as reduction occurs, there is a possibility that the quality of the product may be reduced.

  On the other hand, in the present embodiment, during the can making, the dry air is blown from the air blowing device 10 toward the surface of the piston shaft 7 so that it flows through the inside of the punch 6 at 20 ° C. or less (for example, Although cold water having a low temperature of 10 ° C. is passed through the inside of the piston shaft 7, no condensation occurs on the surface of the piston shaft 7, and the quality of the product deteriorates due to the condensation (can The galling phenomenon of the resin coating layer on the surface does not occur.

  Specifically, when a resin-coated seamless can having a diameter of about 66 mm, which is generally used as a beverage can, is manufactured at a high speed of 150 cans / minute or more, the punch 6 supplied at 20 ° C. or less is supplied. It is preferable that the chilled water has a temperature of 5 ° C. or less. However, if the chilled water having a temperature of 5 ° C. or less is caused to flow into the punch 6, dew condensation occurs on the surface of the piston shaft 7 when the temperature rises in summer. May occur. On the other hand, dew condensation is not generated on the surface of the piston shaft 7 by blowing dry air toward the surface of the piston shaft 7 so that the surface temperature of the piston shaft 7 does not become lower than the dew point temperature. .

  Note that the drying air blown toward the surface of the piston shaft 7 may be general factory air in the range of 0 to 60 ° C., but heated dry air is preferable, and the temperature of the air is the piston temperature. Although it depends on the ambient temperature around the shaft 7 and the temperature of the water supplied to the punch 6, it should be in a temperature range in which the surface of the piston shaft 7 does not become lower than the dew point temperature in the atmosphere around the piston shaft 7. It ’s fine. As for the air volume, for example, in the case of forming a normal 350 ml beverage can, the air volume is preferably 500 to 3000 liters / minute. In that case, if the air flow rate is less than 500 liters / minute, a sufficient effect of preventing condensation cannot be obtained. On the other hand, if it is more than 3000 liters / minute, it is excessive in preventing condensation and is not economical.

  As mentioned above, although the Example of the manufacturing method and manufacturing apparatus of the resin-coated seamless can of this invention was demonstrated, this invention is not limited only to the above Examples, For example, inside a die | dye or a punch. The fluid to flow is not limited to the water shown in the embodiment, but may be other fluids such as oil or gas. The flow path through which the fluid flows inside the punch is shown in the embodiment. It is not limited to such a double spiral flow path, and the means for blowing air is not limited to a specific structure such as the air blowing device shown in the embodiment, etc. Needless to say, it can be changed as appropriate.

BRIEF DESCRIPTION OF THE DRAWINGS Explanatory drawing which shows the outline of the whole apparatus about one Example of the manufacturing apparatus of the resin-coated seamless can of this invention. Sectional front view shown by the state cut | disconnected in the direction orthogonal to the axial direction of a piston axis | shaft about the air blowing structure of an air blowing apparatus. The cross-sectional side view shown by the state cut | disconnected in the direction along the axial direction of a piston axis | shaft about the air spraying structure of an air spraying apparatus. Side surface explanatory drawing which shows the arrangement | positioning state of the air spraying apparatus in the state which the punch and piston shaft retracted most. Side surface explanatory drawing which shows the arrangement | positioning state of the air spraying apparatus in the state which the punch and piston shaft advanced most. FIG. 5 is a partially cutaway sectional side view showing an example of a fluid flow path formed inside the punch.

Explanation of symbols

1 Seamless can manufacturing equipment (body maker)
2 Cup body 5 Die 6 Punch 7 Piston shaft 10 Air spraying device 10a Inner wall surface 10c (of the air spraying device) Air blowing hole 11 (of the air spraying device) 11 (Fluid) temperature controller 12 (Fluid) temperature controller 13 (Fluid) temperature controller 14 switching device 16 (air) heating / drying device

Claims (9)

  In a method for producing a resin-coated seamless can such that a cup body integrally formed from a resin-coated metal plate whose surface that is at least the outer surface of the can is coated with a resin layer is formed into a seamless can through ironing in a dry state. During molding to make the cup body seamless through ironing with a punch and a die in a dry state, the punch is attached through the inside of the piston shaft to the piston shaft that is attached to the front end and extends in the direction of movement of the punch. A method for producing a resin-coated seamless can characterized by causing a cooling fluid to flow inside and blowing air for drying toward the surface of the piston shaft.   2. The resin-coated seamless according to claim 1, wherein the air blown toward the piston shaft is heated so that the ambient temperature around the piston shaft to which the punch is attached does not become lower than the dew point temperature. Manufacturing method of can body.   The resin coating according to claim 1 or 2, wherein the air blown toward the surface of the piston shaft is blown toward the circumferential direction of the piston shaft and toward the retreating direction of the piston shaft. A method for producing a seamless can body.   When a cup body is formed into a seamless can through ironing in a dry state with a punch and die maintained at a temperature of 120 ° C. or lower, the lubricant applied to the surface of the resin-coated metal plate is the surface of the cup body. However, while the temperature of the fluid supplied to the inside of the die is kept at a temperature slightly higher than the melting point of the lubricant, only the fluid supplied to the inside of the punch through the piston shaft is molded. The resin-coated seamless can according to any one of claims 1 to 3, wherein the fluid is switched from a fluid having a temperature higher than the melting point of the lubricant to a fluid having a temperature of 20 ° C or less immediately before or after the start. Production method.   The apparatus for carrying out the method according to any one of claims 1 to 4, wherein as a means for blowing air toward the surface of the piston shaft having a punch mounted on the front end side, between the surface of the piston shaft Is provided with an air blowing device having a tunnel-shaped inner wall surface surrounding the surface at a predetermined interval, and a plurality of air blowing holes are opened in the tunnel-shaped inner wall surface. Manufacturing equipment for resin-coated seamless cans.   The apparatus for producing a resin-coated seamless can according to claim 5, wherein a distance between the tunnel-shaped inner wall surface of the air spraying device and the surface of the piston shaft is set to 0.3 to 2 mm.   The air blown out from the plurality of air blowing holes flows in a certain direction along the circumferential direction of the surface of the piston shaft between the surface of the piston shaft and the inner wall surface of the air blowing device. The apparatus for producing a resin-coated seamless can according to claim 5 or 6, wherein the blowing direction of the holes is inclined at a uniform angle with respect to the surface of the piston shaft as viewed from the axial direction of the piston shaft. .   The air blowing direction of each air blowing hole is such that the air blown out from the plurality of air blowing holes flows in the direction opposite to the die side between the surface of the piston shaft and the inner wall surface of the air blowing device. The apparatus for producing a resin-coated seamless can according to any one of claims 5 to 7, wherein the apparatus is inclined toward a retreat direction of the punch.   The blowing direction of the air blowing hole is uniformly inclined in the range of 10 to 60 degrees with respect to the surface of the piston shaft when viewed from the axial direction of the piston shaft, and is 30 to 70 degrees toward the retracting direction of the punch. The apparatus for producing a resin-coated seamless can according to claim 7 or 8, wherein the apparatus is uniformly inclined in a range.

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