JP4879644B2 - Resin-coated seamless can manufacturing method and apparatus - Google Patents

Description

The present invention relates to a resin-coated seamless can manufacturing method and apparatus, and in particular, to an improved technique for improving the manufacturing efficiency of a resin-coated seamless can.
More specifically, a cup obtained by drawing a resin-coated metal plate provided with a thermoplastic resin coating layer on one or both sides of the metal plate is thinned and deep-drawn or drawn and ironed in a dry state to form an elongated can body. It is related with efficiency improvement of the resin-coated seamless can manufacturing method for forming.

Conventionally, many seamless cans (two-piece cans) have been used as containers for various beverages and foods.
In order to produce a seamless can, for example, a disk is formed by punching a disk, redrawing, side wall ironing, bottom forming, trimming the can body to a predetermined height, and washing. In particular, seamless cans for beverage cans are subjected to outer surface coating, printing, inner surface coating, necking and flange processing.

By the way, in recent years, resin-coated seamless cans are often used as steel or aluminum seamless cans (two-piece can bodies) used as containers for various beverages and foods.
The resin-coated seamless can is manufactured from a resin-coated metal plate in which the surface of the metal plate (at least the surface that becomes the outer surface of the can) is coated with a resin layer of a thermoplastic resin. In the manufacture of resin-coated seamless cans, a lubricant is applied in advance to the surface of the resin-coated metal plate (on the resin layer), which makes the cup body of the intermediate molded product squeezed and ironed. Thus, when forming into an elongated bottomed cylindrical seamless can, it is performed in a dry state in which the cooling lubricant (coolant) is not sprayed. Thereafter, the lubricant applied to the resin-coated metal plate and adhered to the can body is volatilized by heating and removed from the seamless can.

  According to the manufacturing method in the dry state of the resin-coated seamless can, it is possible to omit the degreasing / cleaning / chemical conversion treatment step and the waste water treatment facility for the conventional seamless can production. For this reason, the manufacturing method in the dry state can greatly eliminate the cost of fuel, electricity, water and other auxiliary materials consumed in the treatment process, and the cost of the equipment, and has a small impact on the environment. Therefore, it can be said that this is a desirable method for making cans at present when environmental problems have become a major social problem.

However, with regard to the can manufacturing method in the dry state, there is no practical problem in the case of can manufacturing at a relatively low speed of about 100 cans / minute to 150 cans / minute or less, but a cooling lubricant (coolant) is used. In the case of high-speed can manufacturing such as seamless can manufacturing, the application becomes difficult.
For this reason, high speed is also desired in the production in the dry state. To meet such a demand, for example, after performing the redrawing-ironing processing and bottom processing in the dry cup in the dry state, punching is performed. A method and an apparatus for producing a resin-coated seamless can using a body maker that pulls out a can from a known method are known (see Patent Documents 1 and 2).

  In Patent Document 1, when the punch is retracted, the end face of the seamless can body engages with the fingers of the stripper device, and the seamless can body is pulled out from the punch. Trimmers with inner and outer blades that are normally used, because they are thicker than the main part of the body, and the end faces have irregular irregularities due to the occurrence of ears, etc. By the above, the trimming process is performed to a predetermined height in the vicinity of the end surface forming the uneven shape, and after trimming, the seamless can body is heated to about 200 ° C. to volatilize and remove the lubricant (lubricant). After that, after printing on the outer surface and then drying the printed film, it is described that the neck-in part and the flange part are formed at the opening end part, and a seamless can having the neck-in part and the flange part is manufactured. The That.

  In Patent Document 2, a can body formed into a bottomed cylindrical shape obtained by deep drawing and ironing a molded cup by a body maker is directly connected to the body maker. It is described that the upper opening is trimmed by a body trimmer and aligned to a predetermined height. Furthermore, the distortion of the resin coating caused by molding in the heat set oven is removed, the predetermined printing is performed on the outer surface, baking is performed, and then the neck flange is molded to produce a resin-coated aluminum squeezed iron can body. It is described that.

JP 2002-178049 A JP 2002-219538 A

However, in Patent Documents 1 and 2, the following problems remain in improving the production efficiency of the resin-coated seamless can, and there has been no appropriate method for solving this conventionally. It was.
In other words, unlike conventional DI cans, resin-coated seamless cans form seamless cans in a dry state, so the can axially pulling force and the circumferential compression act in a complex manner at the top of the can body. , Adhesion loss or peeling called metal delamination easily occurs between the metal and the resin, and when this resin-coated seamless can is trimmed at the open end of the can body like a conventional DI can, Even if the metal part is cut, the coating resin layer is not cut and the scrap is discharged while attached to the can, so-called “scrap residue” occurs, and the equipment is stopped so that there is no hindrance to the transfer to the next process. There was a problem that the production efficiency was greatly reduced because the defective can had to be removed.

  In addition, a part of the coating resin layer may be peeled off to expose the metal surface of the edge portion, or the coating resin layer may be stretched to generate a film hair extending in a thread shape from the trim end surface. When film hair is generated in this way, the resin in that part becomes heat-shrinked in the heat treatment process in the latter stage and becomes a hump-like shape, and this neck becomes the starting point when neck and flange processing is performed to induce galling. The outer surface resin coating layer is damaged to reduce the corrosion resistance and to induce flange cracking. In addition, there is a problem that the appearance quality is deteriorated due to dirt caused by rubbing of the exposed metal surface.

  The present invention has been made in view of the above-described problems of the prior art, and the purpose thereof is to allow the resin-coated seamless can to be produced more efficiently and to adhere the coated resin layer that is likely to occur in the trim process after the can-making. An object of the present invention is to provide a resin-coated seamless can manufacturing method and an apparatus therefor which are free from various problems due to deterioration of properties and which are excellent in transportability, corrosion resistance, and appearance after canning.

<Manufacturing method>
In order to achieve the above object, a resin-coated seamless can manufacturing method according to the present invention includes a cup molding step and a body molding step.
A first trim step, a heat treatment step, and a second trim step are provided.
Here, in the cup molding step, a thermoplastic resin-coated metal plate coated with a lubricant is molded into a cup.
Further, the body forming step is provided at a subsequent stage of the cup forming step, and the cup is formed in a dry state to obtain a can body in which a body portion and a bottom portion are integrally formed.
The first trim step is provided at a subsequent stage of the body forming step, and trims at a position where the ear portion of the opening end portion of the can body is shifted to the edge side from the predetermined cutting position.
The heat treatment step is provided after the first trim step, and the lubricant is heated and removed from the can body, and at least the opening end of the can body is heated to a temperature equal to or higher than the melting point of the resin. Then, the can body is heated.
The second trim step is provided at a subsequent stage of the heat treatment step, and cuts off the opening end of the can body at a predetermined cutting position.

In the present invention, the body forming step uses a die and a punch to make a can body in which a body portion and a bottom portion are integrally formed from a cup made in the cup forming step,
In the first trim step, after forming the body portion and the bottom portion in the body forming step, an ear of the opening end portion of the can body that has been removed from the punch using a stripper provided in front of the die. When cutting the part, remove the ear part as a cutting position a position shifted to the edge side from the default cutting position,
In the heat treatment step, the can body obtained in the first trim step is placed in an inverted state on the conveyor with its bottom portion up, and conveyed in a heating oven, at least the open end portion of the can body Is heated to a temperature equal to or higher than the melting point of the resin to heat and remove the lubricant from the can and melt the resin,
In the second trim step, it is preferable that the opening end portion of the can body cooled after the resin is melted in the heat treatment step is cut off at a predetermined cutting position.

  In the present invention, the first trim step may be performed at a position shifted from the predetermined cutting position to the edge side within a range of 0.5 mm to 5 mm, preferably within a range of 0.5 mm to 2 mm. It is preferred to cut the ears at the open end of the body.

  That is, if the ear portion is cut at a position closer than 0.5 mm from the predetermined cutting position to the edge side, the second trim process at the subsequent stage may not be performed smoothly, whereas the predetermined cutting position from the predetermined cutting position to the edge side may be more than 5 mm. This is because if the cutting is performed at a distant position, the ear portion may not be completely cut, and the conveyance or heat treatment process to the subsequent stage of the can body may not be performed smoothly.

In the present invention, the heat treatment step further comprises making the thermoplastic resin of the can body non-oriented amorphous,
In the second trim step, it is preferable that the opening end portion of the can body covered with the non-oriented amorphous thermoplastic resin is cut off at a predetermined cutting position.

In the present invention, the outer surface of the can body is provided with a decoration process for printing and / or painting,
It is preferable that the second trim process is provided in a stage prior to the decoration process.

Further, in order to achieve the above object, a resin-coated seamless can manufacturing method according to the present invention is a resin-coated seamless can manufacturing apparatus including a cup forming means and a body forming means.
The first trimmer, the heat treatment means, and the second trimmer are arranged in order.
Here, the cup molding means molds a thermoplastic resin-coated metal plate coated with a lubricant into a cup.
Further, the body molding unit molds the cup obtained by the cup molding unit in a dry state to obtain a can body in which a body part and a bottom part are integrally molded.
The first trimmer is trimmed at a position where the ear portion of the opening end of the can obtained by the body forming means is shifted to the edge side from the predetermined cutting position.
The heat treatment means heats and removes the lubricant from the can obtained by the first trimer, and at least the open end of the can is heated to a temperature equal to or higher than the melting point of the resin. The can body is heated.
The second trimer cuts off the open end of the can obtained by the heat treatment means at a predetermined cutting position.

In the present invention, the first trimmer is a first trimmer cutter that includes an outer blade and an inner blade that are arranged to face each other with the opening end of the can interposed therebetween and have a predetermined clearance and a biting amount. Prepared,
In addition, the second trimmer includes a second trimmer cutter that is disposed to be opposed to each other with the opening end portion of the can interposed therebetween, and includes an outer blade and an inner blade having a predetermined clearance and a biting amount, It is preferable that the amount of engagement between the outer blade and the inner blade of the first trimmer cutter is larger than the amount of engagement of the outer blade and the inner blade of the second trimmer cutter.

<Default cutting position>
The predetermined cutting position here refers to the final cutting position determined based on the desired can body height of the finished product.

<Resin-coated metal plate>
Next, an example of the resin-coated metal plate of the present invention is shown.
That is, as the resin-coated metal plate of the present invention, for example, a polyester resin or a polypropylene resin is previously formed on a metal surface that is at least the outer surface side of a can of a metal plate (metal thin plate) for can manufacturing such as an aluminum alloy plate or a surface-treated steel plate. For example, a coated metal thin plate having a thickness obtained by laminating a protective coating layer of a crystalline thermoplastic resin such as 0.1 to 0.4 mm can be used as an example.
Here, as the polyester resin of the present invention, for example, a copolymer of ethylene terephthalate and ethylene isophthalate, PET, PBT, and a mixture of these resins with other homopolymers or copolymers are particularly preferable.

As a method of laminating to the metal plate, for example, a thermoplastic resin film previously formed into a film is directly heat-bonded to a metal surface of a metal thin plate, and a thermoplastic resin film melted from a T die is preheated. A method of extruding onto a metal thin plate and directly adhering it, or a metal of a metal thin plate through a pre-formed thermoplastic resin film through an adhesive primer layer, a curable adhesive layer, or a thermoplastic resin layer with good thermal adhesion An example is a method of thermally bonding to a surface.
In the present invention, after the thermoplastic resin film thermally bonded with the laminate is once melted, it is rapidly cooled to be amorphous by, for example, passing water, so that the subsequent workability and adhesiveness are improved. This is particularly preferable in consideration.

  Further, as the lubricant applied from above the laminated thermoplastic resin, a lubricant having high temperature volatility, excellent moldability and flavor retention, and no problem in food hygiene can be used. As the lubricant of the present invention, for example, normal butyl stearate, liquid paraffin, petrolatum, polyethylene wax, edible oil, palm oil, synthetic paraffin and the like can be used. As a lubricant of the present invention, by using a high-temperature volatile lubricant that can be removed by volatilization by heating as described above, a large amount of water is not required when removing the lubricant. In addition, the lubricant can be sufficiently removed from the can body by only one heating (heat treatment) step without requiring two steps of a degreasing / cleaning step and a subsequent drying step.

<Invention based on elucidation of cause>
The present invention has been made based on the elucidation of the cause of the conventional problems.
That is, as a result of intensive studies on the production of resin-coated seamless cans, the present inventors have first found out that the cause of the difficulty in improving the production efficiency is as follows.
That is, according to the present inventors, the decrease in the conventional manufacturing efficiency is caused by the occurrence of fine fluffing or the like in the resin layer at the opening end portion (trim edge portion) of the can body after trimming. I understood that. This flaking or the like reduces the appearance dirt and the inner surface quality. This may be difficult to confirm visually, and is a problem that has not been raised in the past.

Such resin-coated seamless cans, like conventional DI cans, the ears at the opening end of the can body are the same cutter conditions (clearance and biting amount as conventional trimmers of DI cans (painted cans)) ) And trim processing, even if the metal part is cut, the resin layer is not cut and the metal scrap is discharged together with the resin layer with the seamless can. Especially, as shown in FIG. The resin coating layer is not cut and scrap remains easily.
In addition, as described above, the resin at the end of the opening has deteriorated adhesion due to severe molding, so after molding the can body, part of the resin layer is peeled off to form a metal exposed part at the trim edge part. Sometimes

In the worst case, a so-called scrap residue occurs in which the scrap metal scrap that should have been cut remains on the trim side of the resin layer.
In this way, if the trimmed cans are discharged with scrap attached, they cannot be transported to the next process, the equipment must be stopped and the defective cans removed, greatly reducing the operating rate. End up.

In view of this, it is conceivable to reduce the cutter clearance of the trimming device so as not to hinder the conveyance to the subsequent process.
However, if the cutter clearance is too narrow, blade spillage or blade wear tends to occur.
Also, at the metal edge, there is a discrepancy between the start and end of cutting, which causes a so-called trimming step that leads to flange cracking, or in the case of an aluminum can, aluminum hair is generated, which is the outer surface of the can body May cause defective printing and deteriorate the appearance.

On the other hand, even when the scrap residue shown in FIG. 7 does not occur, as the adhesiveness of the resin layer decreases during trimming, the coating resin layer is stretched as shown in FIG. Leaning is likely to occur.
As shown in FIG. 9, when this trimming occurs, the trim end face is viewed with a microscope, and several places in the circumferential direction are confirmed to have risen to about several times the resin thickness (about 0.02 to 0.05 mm). In the worst case, a so-called film hair that extends outward from the trim edge in the form of a thread may occur. In addition, when trimming is performed with the resin layer standing off, the resin layer may be attached to the trimmer cutter and peeled off in the circumferential direction to expose the metal surface.

Thus, when the lubricant is removed from the trim can in which delamination or film hair is generated in the subsequent heat treatment process, the resin in the poorly adhered portion is heat-shrinked to form a hump.
For this reason, when performing neck-in processing (neck molding process), the knots become the starting point, causing galling to damage the inner and outer resin coating layers and reducing corrosion resistance, or performing flange processing (flange molding process) When the flange crack occurs. Further, the resin layer is thermally contracted to expose the metal surface, and the appearance quality is deteriorated due to the dirt due to the rubbing of the metal surface.
That is, when heat treatment is performed in a subsequent process on a trim can in which such flaking has occurred, the fluffy resin is thermally shrunk to form a hump, or the resin end recedes from the opening end portion and the exposed metal surface is removed. When it is placed in an inverted state on the conveyor with the trim edge (open end of the can body) facing down and transported inside the heating oven, a part of the indentation is welded to the conveyor surface and transported When the neck-in and flange processing in the final process is performed, the bumps may become the starting point, and the forming tool may be roughened (build-up) or a flange crack may occur.

In addition, the problem of inducing galling in the neck-in part to damage the inner and outer coating layers and lowering the corrosion resistance, or rubbing the exposed metal surface to cause dirt, is just to set the cutter conditions within the appropriate range. Then, it became clear by various experiments that it could not be solved.
Such an appearance stain and an appearance that reduces the quality of the inner surface are difficult to visually confirm, and have not been raised.

  Then, the present inventors have determined that the cause of lowering the production efficiency of the resin-coated seamless can as described above is the above point, and in order to solve these problems, it is a drop molding. It is very important to eliminate various problems caused by the reduced adhesion of the coating resin layer that tends to occur when trimming the opening end of the can body afterwards. We have found that it is very important to produce excellent resin-coated seamless cans.

The present inventors paid attention to the above points, and arrived at the problem solving means of combining the first trim step, the heat treatment step, and the second trim step.
As a result, the present invention has an extremely excellent effect that a resin-coated seamless can can be more efficiently produced as compared with the conventional method.

According to the resin-coated seamless can manufacturing method and apparatus according to the present invention, since the first trim step, the heat treatment step, and the second trim step are provided in order, it is more efficient than the conventional method. A resin-coated seamless can can be produced.
In the resin-coated seamless can manufacturing method according to the present invention, in the first trim step, by cutting the ear portion of the opening end of the can body at a position shifted by 0.5 mm or more from the predetermined cutting position to the edge side. The resin-coated seamless can can be produced more efficiently.
In the method for producing a resin-coated seamless can according to the present invention, the can body after the heat treatment step is coated with an amorphous non-oriented thermoplastic resin, thereby making the production of the resin-coated seamless can more efficient. Can be done automatically.
In the resin-coated seamless can manufacturing method according to the present invention, the second trim step is provided before the decoration step of performing printing and / or painting on the outer surface of the can body, whereby the resin-coated seamless can The can can be manufactured more efficiently.

  What is characteristic in the present invention is that a lubricant is applied to a resin-coated metal plate coated with a resin on the surface of the metal plate at least on the outer surface side of the can in order to efficiently produce a resin-coated seamless can. A cup is made by drawing and thinning the cup in a dry state, deep drawing or drawing ironing is performed to form a can body in which the body and bottom are integrally molded, and a seamless can body is formed with a stripper. The following points were made in the production of the resin-coated seamless can that was pulled out from the punch.

  That is, in the present invention, the first trim processing is performed at a position where the ear portion of the opening end portion of the can body in which the body portion and the bottom portion are integrally formed as described above is shifted to the edge side from the predetermined cutting position. , Scrap removal. Next, the trimmed can body lubricant is removed by heating, and at least the trim edge portion is heated to a temperature higher than the melting point of the resin composition to melt the resin composition. Then, the coating resin around the periphery of the opening is attached to the metal surface of the trim portion. After that, the main feature is that the second trimming step of cutting off the opening end of the can body at a predetermined cutting position is performed. For this reason, in this embodiment, the following resin-coated seamless can manufacturing method is adopted.

Hereinafter, a preferred embodiment of the present invention will be described with reference to the drawings.
FIG. 1 shows a schematic configuration of a resin-coated seamless can manufacturing (apparatus) process for performing a resin-coated seamless can manufacturing method according to an embodiment of the present invention.
The resin-coated seamless can manufacturing (equipment) process 10 shown in the figure includes a cup maker 12, a body maker 14, a first trimmer 16, a heat treatment means 18, a second trimmer 20, a decoration process 22, and a drying means. 24, a neck forming means 26, and a flange forming means 28.

Here, the cup maker 12 performs a cup molding process (S10).
Moreover, the body maker 14 performs a body shaping | molding process (S12).
The first trimmer 16 performs the first trim step (S14).
The heat treatment means 18 performs a heat treatment step (S16).
The second trimer 20 performs the second trimming step (S18).
The decoration means 22 performs a decoration process (S20) such as printing or painting. The drying means 24 performs a drying process (S22) or an amorphization process.
The neck forming means 26 performs a neck forming step (S24).
The flange forming means 28 performs a flange forming step (S26).

The resin-coated seamless can manufacturing apparatus 10 according to the present embodiment is configured as described above, and the operation thereof will be described below.
That is, in the present embodiment, in the cup forming step (S10), the drawing is performed by applying a lubricant to a resin-coated metal plate in which a thermoplastic polyester resin is coated on at least the outer surface of the metal plate. To make a cup 30.
In the body forming step (S12), the cup 30 is subjected to thinning deep drawing or drawing ironing in a dry state to obtain a can body 32 in which the body portion and the bottom portion are integrally formed.

Thus, the first trimming step (S14) is performed by removing the can body 32, in which the body portion and the bottom portion are integrally formed, from the punch.
That is, in the first trim step (S14), first trim processing is performed at a position where the ear portion 34 at the opening end of the can 32 is shifted to the edge side from the predetermined cutting position, and scrap is removed.
Next, in the heat treatment step (S16), the lubricant in the trimmed can body 32 is removed by heating, and at least the trim edge portion is heated to a temperature equal to or higher than the melting point of the resin composition. The composition is melted, and the coating resin around the periphery of the opening is adhered to the metal surface of the trim portion.
Thereafter, the second trim step (S18) is performed. That is, in the second trimming step (S18), the opening end of the can body 32 is cut off at a predetermined cutting position. At this time, the edge portion (excess portion) 36 is completely scrapped from the can 32.

For this reason, according to the present embodiment, it is possible to solve problems such as flaking due to a decrease in the adhesiveness of the coating resin layer, which is likely to occur in the trim step of removing the ear portion of the can body after the drop molding.
And according to this embodiment, the manufacturing method of the resin-coated seamless can excellent in the conveyance property after can-making, corrosion resistance, and the external appearance can be provided.

Therefore, in the present embodiment, the first trim step (S14) is carried out to such an extent that it does not affect the conveyance even if such a flaking or a metal exposed surface is formed. Thereafter, the resin layer at the opening end of the can is firmly fused to the metal plate surface through a heat treatment step (S16) for removing the lubricant, and then cut off at a predetermined cutting position in the second trim step (S18).
As a result, in this embodiment, by trimming the opening end portion of the can body having improved adhesion in the second trim step, scrap remaining due to defective cutting of the resin layer or resin from the trim portion It is possible to reliably eliminate the occurrence of layer peeling and film hair. In addition, in this embodiment, even if a fluff or a metal exposed portion is formed in the first trim step (S14), it can be surely removed in the second trim step (S18), so that the appearance is improved. Cans can be obtained.
Therefore, in this embodiment, the resin-coated seamless can can be efficiently manufactured.

By the way, in this embodiment, it is also very important to apply the first feature point to the following means (processes) in order to further improve the efficiency of the production of the resin-coated seamless can.
That is, if only the trim part (open end of the can) is heat-treated after the body maker without performing the two trimmings of the first trimming process and the second trimming process, only one trimming is the same as the present invention. You might think that the effect of.
However, according to the present inventors, in the manufacture of a resin-coated seamless can, the lubricant must be removed before printing on the outer surface, and heat setting is required. Before the trimming, a heat treatment test was performed, but it is very difficult to heat uniformly in a short time (heating so as to obtain the above-described excellent effects of the present invention). In order to further improve the efficiency of the production of the resin-coated seamless can, it is particularly preferable to use a solution means that is a combination of the first trim step, the heat treatment step, and the second trim step.

  For this purpose, the present invention applies a lubricant to a resin-coated metal plate coated with a thermoplastic polyester resin on at least the outer metal surface of the metal plate to make a cup, and the cup is then dried. A thin-walled deep drawing or drawing ironing process is performed to obtain a can body in which the body portion and the bottom portion are integrally formed, the opening end portion is cut, and neck-in and flange processing are performed. The manufacture includes the following first trim step, heat treatment step, and second trim step.

Here, the first trimming step is performed when a can body formed by using a stripper provided in front of the die is removed from the punch, and subsequently the ear portion at the opening end of the can body is cut. The ears are removed with the position shifted from the cutting position to the edge as the cutting position.
In the heat treatment step, the can body obtained in the first trim step is placed in an inverted state on the conveyor with the bottom facing up and conveyed in a heating oven to rise to a temperature equal to or higher than the melting point of the resin composition. While being heated, the lubricant is removed by heating, and the resin composition is melted to remove distortion of the coating resin.
Then, the second trimming step cuts off the open end of the cooled can body at a predetermined cutting position.

  As described above, according to the present invention, the lubricant is removed by heating by placing it in an inverted state on the conveyor with the bottom portion facing up and the opening end portion facing downward, and the resin composition is heated and removed. Is heated to a temperature equal to or higher than its melting point, and the resin composition is melted to improve the adhesion of the coating resin layer. Here, excessive melting treatment makes it easy for the resin melted at the lower end opening to adhere to the conveyor, leading to peeling of the resin at the edge when it is discharged from the conveyor. By cutting off the open end of the can body at a predetermined cutting position in the two trim step, it becomes possible to perform scrap processing including the exposed metal portion.

Hereinafter, the feature points will be described more specifically.
That is, the resin-coated seamless can manufacturing method according to the present embodiment includes a cup forming step (S10), a can body forming step (S12), a first trim step (S14), a heat treatment step (S16), and a second step. A trimming step (S18), a decoration step (decoration step) (S20), a drying step (S22), a neck forming step (S24), and a flange forming step (S26) are provided.
In this embodiment, a non-oriented amorphous thermoplastic resin layer (such as a thermoplastic polyester resin) is formed on both surfaces of a thin metal plate (such as an aluminum plate), and high temperature volatilization occurs from above the resin. A coated metal sheet coated with a functional lubricant is used as a material for a resin-coated seamless can.

  In the cup forming step (S10), a blank is obtained by applying a lubricant to a coated metal thin plate in which a thermoplastic polyester resin is coated on at least the outer metal surface of the metal plate as described above, and punching it into a disk shape. To draw a cup 30.

After the completion of the cup forming step (S10), a can body forming step (S12) is performed.
That is, in the can body forming step (S12), the cup 30 made in the cup forming step (S10) is subjected to thinning deep drawing or drawing ironing in a dry state using a die and a punch, Makes a can 32 integrally formed.

After the can body forming step (S12) is completed, the can body 32, in which the body portion and the bottom portion are integrally formed, is removed from the punch by using a stripper provided in front of the die, and the first trim step (S14). )I do.
That is, in the first trim step (S14), the ear portion 34 at the open end of the can 32 is cut.
Here, in this embodiment, the first trim processing is performed at a position where the ear portion 34 at the opening end of the can body 32 is higher than a predetermined can height, that is, a position shifted to the edge side from the predetermined cutting position, and scrap Remove.

In the present embodiment, the heat treatment step (S16) is performed after the completion of the first trim step (S14).
In the heat treatment step (S16), the lubricant in the trimmed can body 32 is removed by heating, and at least the trim edge part (opening end part) is heated to a temperature equal to or higher than the melting point of the resin composition. Then, the heat treatment step (S16) is used to melt the resin composition and improve the adhesion of the coating resin at the periphery of the opening to the metal plate surface of the trim portion.

  In the present embodiment, in the heat treatment step (S16), the can body 32 obtained in the first trim step (S14) is placed in an inverted state on the conveyor with the bottom portion up, and is conveyed in the heating oven. The lubricant is heated to be heated up to a temperature equal to or higher than the melting point of the resin composition to remove the lubricant, and the resin composition is melted.

  Therefore, even if the can body 32 is placed in an inverted state on the conveyor with the bottom of the can body 32 facing up and conveyed in the heating oven, there are few contact portions between the trim edge and the conveyor, and the molten resin makes the conveyor surface This effectively prevents the can body from being welded and not separated. Moreover, since the ground contact diameter with respect to a conveyor can be taken large, it can prevent that a can falls during conveyance.

In this embodiment, subsequent to the heat treatment step, at least the opening end of the can body is rapidly cooled to make the coating resin layer amorphous non-oriented, so that the post-processability of the opening end at the latter stage is achieved. (Machinability such as neck molding and flange molding) is improved.
That is, in the second trim step (S18), the open end portion of the can 32 cooled after melting after the heat treatment step is cut off at a predetermined cutting position. In the present embodiment, since the can body 32 is heat-treated in the previous stage, the second trim processing can be performed smoothly.

After the completion of the second trim process (S18), a decoration process such as a printing process (S20) is performed.
In the printing step (S20), a desired design (characters, decorative patterns, etc.) is printed on the cylindrical body of the can 32, and a top coat is applied thereon.
After the application, a drying step (S22) is performed.
That is, in the drying step (S22), the printing ink layer and the topcoat layer are sufficiently dried (baked) by heating.

After such drying is sufficiently performed, a neck forming step (S24) is performed.
In the neck forming step (S24), neck-in processing is performed on the open end portion of the can 32.
In the flange forming step (S26), the opening end portion of the can body 32 is subjected to flange processing.
Thus, the manufacture of the resin-coated seamless can is completed by sequentially performing the neck molding process and the flange molding process on the open end of the can body 32.

Thus, in this embodiment, in the production of the resin-coated seamless can body in the dry state, a heat treatment step is provided between the first trim step and the second trim step.
In other words, the trimming that is normally performed only once is performed twice with the heat treatment step interposed therebetween, that is, the first trimming is performed at a position closer to the edge than the predetermined cutting position with a margin. Trimming is performed with a clearance that prioritizes cutting of the metal plate, and with the amount of biting of the cutter larger than the normal biting amount, ignoring slight resin layer flaking. The final trimming is performed by cutting off the opening end of the can body at a predetermined position.

Thus, since the final trimming is performed after the heat setting, the trimming can be performed smoothly even in the second trim step even with the conventional clearance and overlap amount.
Here, the heat treatment process includes a heat treatment for melting the resin and a heat setting process for removing the lubricant by heating and removing the distortion of the resin layer. Therefore, compared with the case where these processes are performed separately. The process (man-hours) can be simplified.

<High efficiency>
Further, in the present embodiment, in order to further improve the efficiency when manufacturing the resin-coated seamless can, the following steps are also very important, and each step will be described more specifically. .
<First trim step>
In other words, in the present embodiment, the selection of the first trim position in the first trim step is also very important in order to improve efficiency when manufacturing the resin-coated seamless can.
What is characteristic in the present embodiment is that the first trim step cuts the ear portion of the opening end portion of the can body at a position shifted by 0.5 mm or more from the predetermined cutting position to the edge side.

In the present embodiment, the shift amount from the predetermined position to the edge side in the first trim step may be cut between the predetermined cutting position and the trough of the ear, although it depends on the unevenness of the ear. It is preferable to cut a position shifted to the edge side by 0.5 mm or more from the predetermined cutting position, and it is more preferable to cut a position shifted to the edge side by about 0.5 mm to 2.0 mm.
In the present embodiment, as shown in FIG. 2, the first trim position 42 is a position shifted from the predetermined position 40 of the opening end of the can body 32 to the edge side by about 0.5 mm to 2.0 mm, for example. The portion 34 is cut with a first trimmer, and the ear portion 34 is scrapped. In other words, the trimming is performed with the hatched edge portion (surplus portion) 36 added.

3 and 4 show a schematic configuration of a trimmer for performing the first trim step and the second trim step.
3 is a partially enlarged view in which a part of the trimmer 16 (20) is broken, and FIG. 4 is a front view of the trimmer 16 (20) shown in FIG.
The trimmer 16 (20) includes a cylindrical mandrel 50 and a tool wheel 52.

Here, the mandrel 50 is positioned by extrapolating the can body 32. The mandrel 50 rotates about the first rotation shaft 60 together with the spindle 54, the knurled roller 56, and the inner cutter 58.
The tool wheel 52 has a second rotating shaft 62 parallel to the first rotating shaft 60 of the mandrel 50, and includes an outer cutter 64 and a knurl sector 66 on the outer periphery thereof.
Then, the trimmer 16 (20) rotates the mandrel 50 and the tool wheel 52 with each other, and connects the annular inner cutter 58 provided on the mandrel 50 and the arc-shaped outer cutter 64 provided on the tool wheel 52. Then, they are engaged with each other with the opening edge of the can 32 sandwiched therebetween, and the ears are cut off to align the opening ends.

Further, as shown in FIG. 4, the trimmer 16 (20) further includes a plate-like scrap cutter 70 that protrudes radially outward on the outer periphery of the tool wheel 52.
In this scrap cutter 70, an opening edge portion cut out in an annular shape from the can body 32 is pushed and cut on a knurled roller 56 to form a strip-shaped scrap 72.

Here, in order to perform trimming at a more desired position in the trimming process, it is also very important to set the clearance C of the trimmer cutter and the engagement amount (overlap amount) L as shown in FIG. is there.
In the present embodiment, the relationship between the clearance C between the outer cutter (outer blade) 64 and the inner cutter (inner blade) 58 and the biting amount (overlap amount) L is important.

  Normally, it is conceivable to reduce the clearance C of the trimmer cutter in order to prevent the generation of scrap residue. However, when the clearance C of the trimmer cutter is narrowed to cut the film, the trimming step on the metal side trim edge, that is, the gap between the start and end of cutting of the edge portion is likely to occur, and a step is formed. Another problem that causes flange cracks in the process or film hair that extends from the periphery of the trim edge into a thread shape occurs.

  On the other hand, in the present embodiment, the clearance C of the trim cutter in the first trimming step (S14) is slightly larger than the clearance of the normal DI can (6 to 15% of the trim part plate thickness) and is bitten. The amount of scraping (overlap amount) L is larger than the overlap amount (0-0.01 mm) of a normal DI can, so that the resin coating layer can be stretched inward in the radial direction of the can to be broken. It is preferable from a viewpoint of generation | occurrence | production prevention.

  For this purpose, in this embodiment, the biting amount (overlap amount) L of the trim cutter is set from the material and thickness of the metal plate for cans and the clearance C of the cutter. Even if the cutter clearance C is set to an appropriate range, the resin layer is dragged inward as described above, so that the resin layer is hardly cut and the scrap remains. Since the circumferential peeling of the resin layer is likely to occur, the biting amount (overlap amount) L of the first trim cutter is increased and the resin layer is pulled and broken to the edge side from the predetermined position. The first trim step is performed at a position shifted from the predetermined position by 2 mm or more to the edge side, preferably at a position that does not reach the edge of the edge portion, and after the heat treatment step (S16). After restored the adhesion of the covering resin layer, it is important to perform the second trim step (S18) for cutting off in the default position.

In this way, by increasing the biting amount (overlap amount) L of the first trim cutter in the first trim step, the resin layer is pulled and broken, and the remaining scrap is eliminated without causing a trimming step. To be able to.
In addition, it is preferable that the biting amount (overlap amount) L of the first trim cutter in the first trim step is 0.9 times or more the metal plate thickness (Tn) of the trim part. Since the frictional force with the material increases, it is particularly preferred not to exceed twice.
In the second trim step in the subsequent stage, when trimming the opening end portion of the can body that has undergone the heat treatment step, the amount of biting (overlap) is the same as in the first trim step because there is adhesion of the resin layer at the opening end portion. The amount of the resin layer can be trimmed without increasing the amount L), so it is not necessary to make it larger than necessary.

<Amorphization>
In the present embodiment, it is also very important to make the resin amorphous in order to improve efficiency.
That is, a further characteristic feature of the present embodiment is that the can after the heat treatment step is coated with an amorphous non-oriented thermoplastic resin.
Thereby, in the present embodiment, the can body after the heat treatment step is entirely covered with an amorphous non-oriented thermoplastic resin including the periphery of the edge portion, so that neck formation in the latter stage and Post-processability such as flange molding is improved.

Here, in the present embodiment, it is also preferable to use an oven device of the heat treatment means 16 in order to make the resin amorphous.
That is, the oven device of the heat treatment means 16 is used for removing the lubricant and for relaxing or non-orienting the distortion of the resin formed during the can making. This is the state in which the original coated metal thin plate material has been made non-oriented amorphous, but the thermoplastic resin layer oriented in the direction of the can axis by the subsequent can body molding is reheated at this stage. Thus, the resin layer is made non-oriented amorphous.
Moreover, such resin non-oriented amorphization can also be performed in a drying step (S22) in which subsequent printing or coating is dried and baked.

  In this way, the can body is opened to the end of the endless belt conveyor (conveyor) so that the volatilization removal of the lubricant and the amorphization of the thermoplastic resin can be easily performed by the oven device of the heat treatment means 16. It is placed so that the edge surface on the part side is down. For this reason, in the heat treatment step (S16), since the temperature of the can body 32 is raised to the melting point temperature of the thermoplastic resin layer, the film hair extending in a thread form from the edge surface of the can body 32 in the first trim step (S14). It is very important to optimize the cutter clearance C and the biting amount (overlap amount) L in the first trim step (S14) so as not to occur.

<Second trimming process>
In the present embodiment, the arrangement of the second trim step (S18) is also important for the production of the resin-coated seamless can in order to further increase the efficiency.
That is, in the present embodiment, it is possible to provide the second trim process (S18) after the decoration process (S20).
However, in the second trim step (S18), in order to prevent problems such as coating film cracking and edge cracking, restrictions may be imposed on the resin composition of the clear coating. In other words, if the surface becomes too hard after baking with clear paint, it may depend on the composition of the clear paint, but there is a risk of film cracking during trimming, which reduces efficiency. There is also.

  Therefore, in the present embodiment, it is particularly preferable that the second trim step (S18) is performed before the decoration step (S20) in order to further improve the efficiency of manufacturing the resin-coated seamless can. As a result, the second trimming step (S18) can be performed without being affected by the hardening of the clear coating, so that a good trim edge without generation of clear resin powder can be obtained.

As described above, according to the resin-coated seamless can manufacturing method (apparatus) according to the present embodiment, it is possible to manufacture a resin-coated seamless can more efficiently than in the conventional method.
In the present embodiment, an example in which the body forming of the can body and the can bottom forming are completed in the same process is described. However, the present invention is not limited to this, and the can bottom forming is performed before the second trim process (S18). If so, it may be arranged so as to be performed in a separate process from the body forming.

  Hereinafter, a preferable relationship between the clearance C of the cutter and the biting amount L will be described more specifically.

A resin-coated aluminum plate having a metal plate thickness of 0.295 mm and an inner / outer surface film (resin) of 12 μm is used. As this resin-coated aluminum plate, a film of isophthalic acid copolymer polyethylene terephthalate resin as a protective coating layer of a crystalline polyester resin is formed with a thickness of 12 μm on the inner surface side and 12 μm on the outer surface side with respect to the 3004H191 aluminum alloy plate. A coated metal sheet laminated to have a thickness is used.
A lubricant is applied to this resin-coated aluminum plate to make a cup by punching and drawing, and then the cup is redrawn in a dry state at 270 cpm using a punch-out type body maker. A continuous ironing process is applied so that the can body is thinned through the ning die, and the bottom of the can is formed at the doming station at the end of the stroke.

  When the punch stroke begins to return, the can body is pulled out of the punch by the spring-loaded stripper fingers by the air supplied from the ram, and is carried to the first trimmer that is operated synchronously with the body maker by the unloader conveyor, The ear part generated at the opening end is cut.

In the first trim step, the can body having a plate thickness corresponding to the trim portion at the opening end of the can body is cut by about 2 mm from the predetermined cutting position to the edge side in order to cut the ear portion. Trimming was performed at the specified position. At that time, a test was performed to check the state of scrap remaining in the first trim step by changing the setting conditions of the clearance C and the biting amount (overlap amount) L of the trim cutter. The result was as shown in Table 1 below.

  From the above test results, the cutter condition in the first trim step is that the clearance C is set to 20 to 25 μm and the amount of biting (overlap amount) L is set to 0.14 mm or more, thereby performing trimming that does not generate scrap residue. However, when trimming the ears at the opening end of the can body, the metal and resin are greatly different in mechanical properties and the molding is severe at the top of the can body, so the adhesion of the resin layer is reduced. Therefore, although there is no scrap remaining, the resin layer is stretched and cut as the adhesion decreases.

Based on the above test results, in this embodiment, in the first trim step, the position shifted from the predetermined cutting position to the edge portion, the position where the ear portion can be completely cut and removed, preferably from the predetermined position. The first trim step was performed at a position shifted to the edge side by about 0.5 to 2.0 mm.
Subsequently, the can bottom is placed upside down, placed on the conveyor in an inverted state, transported in a heating oven, and heat-treated at an ultimate temperature of 235 ° C. for 30 seconds to make the coated resin layer non-oriented amorphous. After removing the lubricant and making the uniaxial orientation of the resin formed at the time of can making non-oriented and restoring the adhesion to the metal surface of the resin layer, the trim edge is set at a predetermined position in the second trim step. Cut off.

In the present example, the trim edge after the second trim step had no film hair as shown in FIG. 6, and a clean trim end face was obtained.
Here, the setting condition of the second trim cutter in the second trim step is 0.1 mm or less, which is smaller than the biting amount (overlap amount) L (0.14 mm) of the first trim cutter in the first trim step, Preferably, it is 0.07 to 0.1 mm to prevent resin cracking due to the side pressure of the cutter. Preferably, the can obtained in the second trim step was then subjected to the outer surface / printing coating, dried and baked, and then subjected to neck molding and flange molding. As a result, neck-in / flange processing was performed without any particular problems. .

As described above, in the enlarged cross-sectional photograph as shown in FIG. 9, even if a minute flaking is confirmed at the edge portion of the first trim can, as shown in FIG. 6 after the heat treatment step and the second trim step. In addition, the film hair has been eliminated neatly.
Therefore, according to the present Example, the resin-coated seamless can can be manufactured extremely efficiently as compared with the conventional case.

It is explanatory drawing of the schematic structure of the flowchart which shows the process sequence of the resin-coated seamless can manufacturing method concerning one Embodiment of this invention, and the resin-coated seamless can manufacturing process for performing this. It is explanatory drawing of the suitable 1st trim position in this embodiment. It is the partial side view which fractured | ruptured a part of trimmer concerning this embodiment. FIG. 4 is a front view of a part of the trimmer shown in FIG. 3. It is explanatory drawing of the clearance C and the biting amount L of a trim cutter. It is an expanded sectional photograph of the can body opening end part after the 2nd trim process. It is the elements on larger scale which show the state of the scrap remainder in the opening edge part of a can body. It is the elements on larger scale which show the state of fluff standing in the opening edge part of a can body. It is an expanded cross-section photograph which shows the state with fluff standing in the opening edge part of a can body.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Resin-coated seamless can manufacturing apparatus 12 Cup maker 14 Body maker 16 First trimmer 18 Heat treatment means 20 Second trimmer 22 Decoration means 24 Drying means 26 Neck forming means 28 Flange forming means

Claims (7)

A cup molding process for molding a thermoplastic resin-coated metal sheet coated with a lubricant into a cup;
A body molding step that is provided at a subsequent stage of the cup molding step, molds the cup in a dry state, and obtains a can body in which a body portion and a bottom portion are integrally molded;
In a resin-coated seamless can manufacturing method comprising:
A first trim step, which is provided at a subsequent stage of the body forming step, and trims the ear portion of the opening end portion of the can body at a position shifted to the edge side from a predetermined cutting position;
Provided in a subsequent stage of the first trim step, the lubricant is removed by heating from the can body, and at least the opening end of the can body is heated to a temperature equal to or higher than the melting point of the resin. A heat treatment step for heating the can body;
A second trim step, which is provided at a subsequent stage of the heat treatment step, and cuts off the opening end of the can body at a predetermined cutting position;
A method for producing a resin-coated seamless can, comprising: In the resin-coated seamless can manufacturing method according to claim 1,
The body forming step uses a die and a punch to make a can body in which a body portion and a bottom portion are integrally formed from a cup made in the cup forming step,
In the first trim step, after forming the body portion and the bottom portion in the body forming step, an ear of the opening end portion of the can body that has been removed from the punch using a stripper provided in front of the die. When cutting the part, remove the ear part as a cutting position a position shifted to the edge side from the default cutting position,
In the heat treatment step, the can body obtained in the first trim step is placed in an inverted state on the conveyor with its bottom portion up, and conveyed in a heating oven, at least the open end portion of the can body Is heated to a temperature equal to or higher than the melting point of the resin to heat and remove the lubricant from the can and melt the resin,
The second trim step is a method for producing a resin-coated seamless can characterized in that the open end of the can body cooled after the resin is melted in the heat treatment step is cut off at a predetermined cutting position. In the resin-coated seamless can manufacturing method according to claim 1 or 2,
The first trim step cuts the ear portion of the opening end portion of the can body at a position shifted from the predetermined cutting position to the edge side within a range of 0.5 mm or more and 5 mm or less. Can manufacturing method. In the resin-coated seamless can manufacturing method according to claim 1 or 2,
The heat treatment step further comprises making the thermoplastic resin of the can body non-oriented amorphous,
In the second trim step, the opening end of the can body covered with the non-oriented amorphous thermoplastic resin is cut off at a predetermined cutting position. In the resin-coated seamless can manufacturing method according to claim 1 or 2,
The outer surface of the can body is provided with a decoration process for printing and / or painting,
The method for producing a resin-coated seamless can, wherein the second trim step is provided before the decoration step. Cup molding means for molding a thermoplastic resin-coated metal plate coated with a lubricant into a cup;
A body molding means for molding the cup obtained by the cup molding means in a dry state to obtain a can body in which a body portion and a bottom portion are integrally molded;
In the resin-coated seamless can manufacturing equipment equipped with
A first trimmer that trims the edge of the opening end portion of the can obtained by the body shaping means at a position shifted from the predetermined cutting position to the edge side;
The lubricant is heated and removed from the can obtained by the first trimer, and at least the opening end of the can is heated to a temperature equal to or higher than the melting point of the resin. Heat treatment means for heating;
A second trimmer that cuts off the open end of the can obtained by the heat treatment means at a predetermined cutting position;
The resin-coated seamless can manufacturing apparatus characterized by the above. In the resin-coated seamless can manufacturing apparatus according to claim 6,
The first trimmer includes a first trimmer cutter that includes an outer blade and an inner blade that are arranged to face each other with the opening end of the can interposed therebetween, and have a predetermined clearance and a biting amount.
The second trimmer includes a second trimmer cutter that is disposed oppositely across the opening end of the can body and includes an outer blade and an inner blade having a predetermined clearance and a biting amount,
The resin-coated seamless can manufacturing apparatus characterized in that the amount of biting between the outer blade and the inner blade of the first trimmer cutter is larger than the amount of biting of the outer blade and the inner blade of the second trimmer cutter. .