KR20230002779A - Method and apparatus for manufacturing a two-piece can body from a laminated metal plate and the two-piece can body produced thereby - Google Patents

Abstract

The present invention relates to a method and apparatus for producing a two-piece can body by drawing and ironing laminated metal sheets, and more particularly to a processing method for preventing wear damage or scuffing of a laminate layer on a can body during ironing. and a drawn and ironed two-piece can body produced thereby.

Description

Method and apparatus for manufacturing a two-piece can body from a laminated metal plate and the two-piece can body produced thereby

The present invention relates to a method and apparatus for manufacturing a two-piece can body by drawing and ironing laminated metal sheets, and more particularly to a method for forming a laminate layer on a can body during ironing. A processing method that prevents abrasion damage or scuffing, and a drawn and ironed two-piece can body produced thereby.

A laminated metal plate for packaging includes a metal plate and a laminate layer covering one or both surfaces of the metal plate, wherein the laminate layer is formed on the metal plate by heat bonding or direct extrusion to form the laminate layer as described above. It is manufactured by laminating on a metal plate. The laminate layer includes one or more thermoplastic polymer layers.

The laminated metal sheet is used for the production of two-piece cans. Such a can is composed of a can body including a base and a tubular body made of a metal plate coated with a laminate layer on at least one side, and a lid coupled to the can body.

For the production of the can body, a disc (usually round) is produced from the laminated metal sheet, which disc is then deep-drawn into a cup with at least an outer layer of laminate, which is then formed into a can by wall-ironing, wherein the wall-iron passes through a redraw ring and one or more wall-iron rings using a punch in a drawing and ironing machine into a cup. It is made in a single stroke by punching continuously. The external shape of the punch is generally cylindrical, and thus rotationally symmetrical, and may have the same diameter throughout the working part. Alternatively, the punches may have different diameters across the working part as in JP2000042644, EP0402006, WO2019154743, GB2547016.

A separate punch is usually removably secured to the tip of a reciprocating ram in a drawing and ironing machine. The punch provides an internal mandrel on which the can is shaped, drawn and ironed while passing through the one or more wall-iron rings. The temperature of the punch increases due to heat generated by repetitive frictional contact between the punch, the interior of the can body, and the one or more wall-ironing rings through which the punch passes. During wall-ironing, shear forces can become excessively high in the laminate layer itself. This excessive shear increases the risk of damaging the laminate layer. One type of damage is so-called scuffing or abrasion, which damages the laminate layer and results in direct contact between the metal substrate and the wall-ironing tool and/or visually unacceptable laminate layer finish or, very In severe cases, it can lead to rupture of the can body wall. Proper lubrication between the wall-iron tool and the laminate layer is important to avoid scuffing or abrasion damage, and this lubrication can be provided by the polymer layer itself (dry process). However, due to the deformation process, the temperature of the metal plate, the laminate layer, the redrawing and ironing ring and the punch rises. The risk of damaging the laminate layer increases as the temperature of the laminate layer increases. As a result, the temperature of the wall-ironing tool must be kept below a critical value at which the risk of damaging the laminate layer begins to occur, which means that the production rate of drawing- and wall-iring is thereby limited. This threshold value depends on the composition of the laminate layer. In conventional can formations, an externally applied cooling fluid maintains operating temperature conditions. However, in the dry DWI process, no externally applied cooling fluid is used, as the externally applied cooling fluid can contaminate the vessel surface, requiring a post-mold cleaning process that can be costly and environmentally undesirable. don't

US2030084699 discloses a punch assembly comprising means for providing a circumferential channel with coolant capable of cooling the inner surface of a punch disposed at the end of a reciprocating ram in a drawing and ironing machine. However, it has been found that the application of this punch assembly still causes wear damage and scuffing of the can body, especially at high reduction and high speed production of the can body.

An object of the present invention is to provide a method for producing a can body for a two-piece can produced from laminated metal sheets without wear damage or scuffing of the laminate layer.

It is also an object of the present invention to provide a method for producing a can body for a two-piece can produced from laminated metal sheets at a higher speed/reduction without wear damage or scuffing of the laminate layer.

It is also an object of the present invention to provide a method for producing can bodies for two-piece cans at increased production rates and without scuffing of the laminate layer.

It is also an object of the present invention to provide an apparatus for producing a can body according to the present invention.

At least one of the above objects is achieved by a method according to claim 1 below: To prepare a tubular body and a base for a two-piece can from laminated metal sheets by deep-drawing and wall-ironing. A method for producing a can body comprising, wherein a disc is produced from the laminated metal sheet, the disc is deep-drawn into a cup, and then the cup is redrawn and then redrawn. A cup is formed into a can-body by wall-iring, wherein the wall-iron punches the redrawn cup through one or more wall-iron rings with an internally cooled punch assembly to form a single made up of strokes wherein the punch assembly is:

램(ram)(14),

ram (14);

펀치(1)로서, 바람직하게는 상기 램에 제거 가능하게 부착되고, 상기 펀치 조립체는 펀치의 원위 단부 근처 위치(15a)와 상기 펀치의 근위 단부 근처 위치(15b) 사이 상기 펀치의 표면 아래에 내부 환형 공동(15)을 포함하는, 펀치(1), 및

A punch (1), preferably removably attached to the ram, wherein the punch assembly is internally below the surface of the punch between a location (15a) near the distal end of the punch and a location (15b) near the proximal end of the punch. A punch (1) comprising an annular cavity (15), and

상기 내부 환형 공동 내로 냉각 유체를 공급하기 위한 복수의 냉각 유체 입구(16) 및 상기 내부 환형 공동으로부터 상기 냉각 유체를 제거하기 위한 복수의 냉각 유체 출구(17), 여기서 상기 내부 환형 공동에는 상기 펀치의 내부 냉각 효율을 향상시키기 위한 수단이 제공되는, 복수의 냉각 유체 출구(17)를 포함하며,

A plurality of cooling fluid inlets (16) for supplying cooling fluid into the inner annular cavity and a plurality of cooling fluid outlets (17) for removing the cooling fluid from the inner annular cavity, wherein the inner annular cavity has a plurality of cooling fluid outlets (17) of the punch. a plurality of cooling fluid outlets (17) provided with means for improving internal cooling efficiency;

여기서 상기 펀치의 내부 냉각 효율을 개선하기 위한 수단은 상기 냉각 유체 입구에서 상기 냉각 유체 출구로 이동하는 동안 상기 냉각 유체의 난류를 증가시키고 상기 펀치로부터 열을 추출하기 위한 더 큰 냉각 표면을 제공하기 위해 상기 내부 환형 공동 내의 장애물(18)로 구성되며, 상기 장애물은:

wherein the means for improving the internal cooling efficiency of the punch is to increase the turbulence of the cooling fluid while moving from the cooling fluid inlet to the cooling fluid outlet and to provide a larger cooling surface for extracting heat from the punch. consisting of an obstruction (18) in the inner annular cavity, said obstruction being:

- consist of discontinuous obstacles (18), such as shevrons, cylinders, discontinuous walls or discontinuous zigzag walls, or

- a plurality of adjacent helical wall-shaped continuous obstacles (18) defining a plurality of helical cooling channels in the inner annular cavity for guiding the cooling fluid from the cooling fluid inlet to the cooling fluid outlet,

상기 램은 냉각 유체를 상기 냉각 유체 입구에 공급하고 상기 냉각 유체 출구로부터 냉각 유체를 제거하기 위한 수단을 포함하여,

wherein the ram includes means for supplying cooling fluid to the cooling fluid inlet and removing cooling fluid from the cooling fluid outlet;

Efficient internal cooling of the punch during production of the can body prevents wear damage or scuffing of the laminate layer on the tubular body of the can body. here

a. The cooling fluid inlets are arranged closer to the distal end of the punch and the cooling fluid outlets are arranged closer to the proximal end of the punch, preferably the inlets and outlets are arranged in a regular pattern around the circumference of the punch. arranged in a pattern, or

b. The cooling fluid inlets are arranged closer to the proximal end of the punch and the cooling fluid outlets are arranged closer to the distal end of the punch, preferably the inlets and outlets are arranged in a regular pattern around the circumference of the punch. arranged in a pattern, or

c. Cooling fluid inlets of some of the spiral cooling channels are arranged closer to the distal end of the punch, corresponding cooling fluid outlets are arranged closer to the proximal end of the punch, and cooling fluid inlets of other spiral cooling channels are arranged closer to the proximal end of the punch. are arranged closer to the proximal end of the punch, and corresponding cooling fluid outlets are arranged closer to the distal end of the punch, so that some of the spiral cooling channels direct cooling fluid from the distal end of the punch. to the proximal end and other cooling channels conduct cooling fluid from the proximal end to the distal end of the punch, preferably the direction of the cooling fluid alternates from one spiral cooling channel to an adjacent spiral cooling channel; , preferably the inlets and outlets are arranged in a regular pattern around the circumference of the punch.

Thus, the present invention implements three different variants: a, b and c. Variants a and b differ in the location of the inlet and outlet for the cooling fluid in the inner annular cavity with discontinuous or continuous obstacles (spiral cooling channels).

Variant c only relates to an embodiment in which the inner annular cavity is provided with a continuous obstacle in the form of a helical cooling channel.

Preferred embodiments are presented in the dependent claims.

The punch is attached to the end of the ram. Preferably the punch is removably attached to the ram. This means that, for example, if the punch is worn or damaged, a punch whose outer surface is in direct contact with the can body can be replaced without the need to replace the ram. However, the invention is also realized by means of a ram and a punch forming one integral part, wherein the punch is not removably attached to the ram, and the inner annular cavity forms a cavity in the integral ram and punch combination. . If the punch part is welded to the ram, the punch is considered to form an integral part of the ram & punch combination since the punch can no longer be easily removed from the ram. In this structure, when the punch part is worn or damaged, the ram & punch combination must be replaced.

When the punch is removably attached, the obstruction within the inner annular cavity is preferably part of the punch, so that when the punch is removed the obstruction is removed with the punch. Less preferably, the obstacle is formed directly on the ram, so that when the punch is removed from the ram, the obstacle remains on the ram. These two embodiments are morphologically identical when the punch is mounted on the ram.

The method according to the invention is based on improving the internal cooling of the punch assembly by increasing the cooling efficiency. This is achieved by increasing the degree of turbulence of the cooling fluid through the punch and increasing the contact surface between the cooling fluid and the punch. The manner in which the present invention achieves an increase in turbulence in the cooling fluid and increases the contact surface between the cooling fluid and the punch is by placing a discontinuous or continuous obstacle in the inner annular cavity. The punch includes an internal annular cavity extending the length of the punch just below the surface of the punch that comes into contact with the sidewall of the can body during the wall-ironing step. The distance (i.e. wall thickness) between the surface of the punch and the inner annular cavity must be thick enough to withstand the mechanical stress of deep drawing and wall-iron processes and maintain its dimensions, but the surface of the inner annular cavity thin enough to maximize heat transfer from the cooling fluid to the cooling fluid flowing through the cavity. Through this inner annular cavity, cooling fluid can be directed from a cooling fluid inlet at one end of the inner annular cavity to a cooling fluid outlet at the other end of the inner annular cavity. In this way heat can be drawn from the punch by the cooling fluid and the surface temperature of the punch can be kept below a critical value to avoid scuffing or abrasion damage. When there are no obstructions in the inner annular cavity, as in the prior art situation, the cooling fluid flows directly and laminarly between the cooling fluid inlet and outlet. This means that the cooling fluid has little time to absorb heat, and also as a result of the laminar flow, the cooling capacity of the cooling fluid is not used efficiently. It should be noted that typically the redrawing ring and ironing ring also have internal cooling channels which cool the outer laminate layer of the can body. However, most of the heat is dissipated by the cooled punch. This is because it has a much longer contact time and a much larger contact area with the laminate layer.

The cooling fluid is not particularly limited. Water, preferably demineralized water, has proven to be very suitable. A corrosion inhibitor may be added to the cooling fluid.

The obstruction blocks the flow of the cooling fluid and also increases the cooling surface of the punch so that the ability to transfer heat from the punch to the cooling fluid increases as a result of the increased cooling surface and increased turbulence. This is because turbulent flow can absorb more heat than laminar flow.

In one embodiment of the invention the discontinuous obstacles within the inner annular cavity are for example pillars (cylindrical or otherwise), V-shaped, discontinuous short walls perpendicular or angled to the flow of cooling fluid through the cavity, or It may consist of discontinuous zigzag walls. Preferably, the outer shape of the punch is rotationally symmetric with respect to the center line of the ram.

The continuous obstruction prolongs the contact time between the cooling fluid and the punch because the obstruction forces the cooling fluid to take a longer path between the cooling fluid inlet and the cooling fluid outlet, and the contact surface of the inner annular cavity is It is larger because there are discontinuous obstacles within the annular cavity. Also, as a result of the path being lengthened by the successive obstructions, the area in which the cooling fluid has to flow becomes smaller, which in turn increases the turbulence of the fluid.

Thus, the method according to the invention provides a more efficient cooling of the punch and thus a lower surface temperature of the punch compared to punches of the prior art. The lower punch temperature lowers the temperature of the laminate layer during the wall-ironing process, preventing scuffing or abrasion damage of the fragile laminate layer and allowing for increased production rates of the can body, which can increase the production rate of the laminate layer. This is because punch temperatures at which the risk of scuffing or abrasion damage becomes noticeable are reached at higher production rates than in the prior art situation.

In one embodiment of the invention (variant a) the cooling fluid inlet is arranged closer to the distal end of the punch and the cooling fluid outlet is arranged closer to the proximal end of the punch. Preferably the inlets and outlets are arranged in a regular pattern around the circumference of the punch. In another embodiment of the invention (variant b) the cooling fluid inlet is arranged closer to the proximal end of the punch and the cooling fluid outlet is arranged closer to the distal end of the punch, preferably the inlet and outlet are arranged closer to the punch's distal end. arranged regularly around the circumference. In variants a and b, the means for improving the internal cooling efficiency of the punch consists of discontinuous obstacles or of continuous obstacles in the form of a plurality of adjacent spiral walls defining a plurality of spiral cooling channels in the inner annular cavity.

In another embodiment of the invention (variant c) the continuous obstacle is a helical wall in the inner annular cavity and thus forms a helical cooling channel in the inner annular cavity. In this embodiment some of the cooling fluid inlets are arranged closer to the distal end of the punch and other cooling fluid inlets are arranged closer to the proximal end of the punch so that some of the spiral cooling channels are drawn from the distal end of the punch. A cooling channel conducts cooling fluid to the proximal end and another cooling channel conducts cooling fluid from the proximal end to the distal end of the punch, preferably the direction of the cooling fluid alternates from one spiral cooling channel to an adjacent spiral cooling channel.

A spiral is shaped like a spiral staircase. It is a kind of smooth spatial curve with a tangent at a constant angle to a fixed axis. A circular helix with radius a and slope b/a (or pitch 2nb) is described by the following parameterization:

x(t)=a cos(t) y(t)=a sin(t) z(t)=b t

According to the present invention the number of spirally continuous obstacles should be such that a plurality, preferably at least three spiral cooling channels are formed. Each spiral cooling channel is preferably provided with its own cooling fluid inlet and its own cooling fluid outlet. The inventors have found that three or more spiral cooling channels lead to very efficient cooling. This is because the length of the channel is required to allow the cooling fluid to effectively and efficiently cool the working surface of the punch. The use of one or two cooling channels greatly reduces cooling efficiency and increases the risk of scuffing or abrasion damage to the laminate layer. Preferably the punch comprises at least 4 contiguous helical cooling channels, more preferably at least 5 contiguous helical cooling channels, even more preferably at least 6 contiguous helical cooling channels. The inventors have found that six channels result in an optimal combination of cooling capacities without unduly complicating the design of the punch. Preferably the inlets and outlets for the cooling fluid are in a regular pattern around the circumference of the punch, i.e. 60° between each inlet or outlet around the circumference in the case of a six-channel embodiment, or 72 degrees in the case of a five-channel embodiment. arranged in degrees. While it is possible to feed two or more helical channels with one inlet or bleed two or more helical channels with one outlet, it is preferred that each channel be fed to its own cooling fluid inlet and bleed through its own cooling fluid outlet. Separate inlets and outlets for the cooling fluid also allow alternating flow direction between adjacent helical cooling channels, potentially achieving much more uniform cooling of the punch.

The advantage of the inlet being arranged at the distal or proximal end of the punch and the corresponding outlet being arranged at the proximal or distal end of the punch is that the cooling liquid moves directly from the inlet at one end of the punch to the other, resulting in direct maximum cooling effect. means that can be achieved. In the prior art such as JP2006055860, JP2006-055860 and JP2005-288483, the cooling liquid has to move up and down the punch because both the inlet and outlet of the cooling liquid are located at the proximal end of the punch. JP2006055860 discloses a punch with a continuous zigzag channel, while JP2006-055860 and JP2005-288483 disclose an embodiment with a single spiral channel and an embodiment with a continuous zigzag channel through which cooling liquid passes.

In prior art such as JP2006055860, JP2006-055860 and JP2005-288483, the returning reheated cooling liquid meets the cooler cooling liquid to heat the incoming cooling liquid. This reduces the cooling capacity of the incoming cooling liquid, thereby reducing the cooling efficiency of the cooled punch as a whole. This prior art configuration therefore has a significantly reduced cooling capacity compared to the configuration according to the present invention.

The external temperature of the punch may be continuously monitored, for example by direct contact or non-contact measurement of the punch temperature or by monitoring the temperature of the cooling fluid entering and exiting the punch. In one embodiment of the present invention, the temperature of the punch assembly is controlled by a temperature control unit, wherein the temperature control unit adjusts the production rate of the can body and/or the flow of cooling fluid entering the inner annular cavity. The temperature of the punch can be controlled by adjusting the cooling rate and/or by adjusting the temperature of the cooling fluid entering the inner annular cavity.

In one embodiment, the redrawing ring and the one or more ironing rings also have internal cooling channels, which allow cooling of the outer laminate layer of the can body during the deep drawing and wall-iring.

The invention is also embodied in a punch assembly according to claim 6 . Preferred embodiments are presented in the dependent claims.

The punch according to the present invention can be provided with the barrier in two ways. Since the inner annular cavity provided with the discontinuous or continuous obstacle is structurally quite complex, it is preferable to produce the punch through additive manufacturing such as 3D printing. By means of additive manufacturing, a punch with an outer surface in contact (in use) with the laminate layer of the can body, comprising the complex internal structure of the inner annular cavity, can be produced as one integral part in one production step. there is. For example, a punch as shown in FIG. 4 can be produced by additive manufacturing in one production step so that the punch sleeve 19 and the insert 20 can be made as one piece. Here, the punch sleeve and the insert are combined as one part, that is, as one integrated part, and cannot be separated. The channels or obstructions within the inner annular cavity are produced simultaneously with the rest of the punch when the punch is produced by additive manufacturing. The production of such punches with complex shapes of discrete obstacles in the inner annular cavity cannot be produced as one integral part, ie as one integral part, by classical machining.

Alternatively, the punch may be produced from two or more parts: a punch sleeve and an insert, which when joined together form an internal annular cavity with discontinuous or continuous obstacles (eg adjacent helical channels). The obstructed insert may be produced by additive manufacturing (AM), wherein the insert also has a cooling fluid inlet from tool steel, cemented carbide such as WC, or a material suitable for AM such as copper or copper alloys. and a cooling fluid outlet. Alternatively, the insert may be produced by machining an insert from another suitable material, such as for example tool steel or stainless steel, copper or a copper alloy.

The material of the punch with integrated internal structure in the internal annular cavity or the insert with discontinuous or continuous obstacles in the internal annular cavity (after assembly with the punch sleeve) is preferably cemented carbide, WC, or AM such as copper or copper alloy. It is a suitable material for

The invention is also embodied in a can body manufactured according to the method or apparatus according to the invention.

A laminated metal plate for packaging includes a metal plate and a laminate layer covering at least one surface of the metal plate. Such a laminated metal sheet is produced by laminating a laminate layer on a metal sheet. The laminate layer may be applied to the metal plate by thermally bonding the laminate layer to the metal plate, or by using an adhesion promoter between the laminate layer and the metal plate, or by using a laminate layer comprising an adhesive layer. The laminate layer may be produced in-line and laminated onto the metal plate in an integrated lamination step, or a pre-produced laminate layer may be laminated onto the metal plate in a separate lamination process step. Another lamination method is to extrude a laminate layer using a flat die and laminate the laminate layer directly onto a metal plate.

The ironing method of the present invention is particularly effective for ironing metal sheets selected from the group of metal sheets such as cold rolled steel, blackboard, tinplate, ECCS, TCCT®, galvanized steel, or aluminum or aluminum alloys. The metal plate is preferably supplied in a coil form.

The metal sheet is preferably coated on one or both sides with an organic resin selected from polyesters, polyolefins, polyamides and other thermoplastics. The resin film to which the present invention is applied may be a film formed of a single layer or a film of two or more layers, and is preferably a film of a thermoplastic resin, particularly a polyester resin.

The polyester resin preferably has an ester unit such as ethylene terephthalate, ethylene isophthalate, butylene terephthalate, or butylene isophthalate, and is preferably a polyester mainly containing one or more ester units selected from these. Do. Each ester unit may be a copolymer, and the polyester may be a mixture of a homopolymer or a copolymer of two or more ester units. It also contains, for example, naphthalenedicarboxylic acid, adipic acid, sebacic acid or trimellitic acid as an acid component, or, for example, propylene glycol, diethylene glycol, neopentyl glycol, cyclohexanedimethanol or pentachlorethylene glycol. Other ester units containing erythritol as an alcohol component may also be used.

The polyester may be a laminate of two or more polyester layers consisting of a homopolyester or a copolyester, or a mixture of two or more thereof. For example, the polyester film may have a co-polyester layer having high heat adhesion as a lower layer and a polyester or modified polyester layer having high strength, heat resistance, and barrier properties against corrosive substances as an upper layer. .

The thickness of the resin film is preferably 5 to 100 μm, more preferably 10 to 40 μm in the case of a single layer film. A film with a thickness of less than 5 μm is very difficult to laminate on a surface-treated steel sheet, prone to resin layer failure during drawing or drawing and ironing, impermeability to corrosive substances when forming and filling cans this is not satisfactory Increasing the thickness provides satisfactory impermeability, but a thickness exceeding 100 μm is economically disadvantageous. The thickness ratio of the layers of the multilayer film varies depending on moldability, imperviousness, etc., and the thickness of the layers is adjusted so that the total thickness is 5 to 60 μm.

The resin film may be formed from a resin to which color pigments, stabilizers, antioxidants, lubricants, and the like are added within a range that does not impair required properties. It is possible to use a metal plate on which a non-dyed polyester resin film is laminated on the side to form the inner surface of the can and a polyester resin film containing a pigment such as titanium oxide is laminated on the side to form the outer surface of the can. .

Figure 1 shows how a preformed deep-drawn cup 3 is formed into a finished wall-ironing can body 9.
2 provides a detailed illustration of the passage of a portion of the can wall to be formed, for example through a wall-ironing ring 6 .
Figure 3 shows a punch 1 removably secured to the tip of a reciprocating ram 14, typically in a drawing and ironing machine.
Figure 4 shows a cross-section of a punch with continuous obstacles forming adjacent helical cooling channels.
5a shows the outer surface of an insert 20 with a helical continuous obstacle 18 .
Figure 5b shows a cross-section of the same insert used in Figure 4.
6a to 6e show six different examples of internal annular cavities.
7 shows the surface temperature of various examples.
8 shows the effect of these low surface temperatures.

The invention is further illustrated by the following non-limiting figures.

Figure 1 shows how a preformed deep-drawn cup 3 is formed into a finished wall-ironing can body 9. The cup 3 is placed between the redrawing sleeve 2 and the redrawing die 4 . When the punch 1 moves to the right, the cup 3 has the inner diameter of the can 9 finally completed by the re-drawing step. The punch 1 then successively pushes the product through the two wall-ironing rings 6, 7 (in this example). Ring 8 is an optional stripper ring. Wall-ironing causes the can body 9 to be formed to a final wall thickness and wall length. Finally, the bottom of the can body 9 is formed by moving the punch 1 towards the optional base tool 10 . When the punch 1 is retracted, the can 9 can be separated from the punch 1 and discharged in the horizontal direction. The optional stripper ring above can help with this. The can 9 is then filled, after trimming, optional necking, flange forming, and then provided with a lid.

2 provides a detailed illustration of the passage of a portion of the can wall to be formed, for example through a wall-ironing ring 6 . The punch 1 is shown schematically. The inlet plane of the wall-ironing ring 6 runs at an inlet angle α with respect to the axial direction of the wall-ironing ring. The thickness of the wall material to be formed is reduced between the punch (1) and the wall-ironing ring (6). This material comprises a real metal can body wall 11 with laminate layers 12, 13 on either side. Laminate layer 12 becomes the exterior of the can body, and laminate layer 13 becomes the interior of the can body and ultimately comes into contact with the contents of the can. The figure shows how the thickness of all three layers 11, 12, 13 is reduced.

Figure 3 shows a punch 1 removably secured to the tip of a reciprocating ram 14, typically in a drawing and ironing machine. Figure 3 shows a detail of the punch on top of the ram in one of the embodiments of the present invention. The inner annular cavity is between 15a and 15b and is more prominently outlined by the dotted box in the cross-section of the punch in FIG. 4 .

Figure 4 shows a cross-section of a punch with continuous obstacles forming adjacent helical cooling channels. In this figure, the punch consists of a punch sleeve 19 and an insert 20. The inner annular cavity formed by the combination of the punch sleeve and the insert is filled with a continuous obstacle.

5a shows the outer surface of an insert 20 with a helical continuous obstacle 18 . This figure shows six adjacent spiral cooling channels (channels a-f), each with a separate inlet and outlet for cooling fluid. Figure 5b shows a cross-section of the same insert used in Figure 4.

Figures 6a to 6e show six different examples of internal annular cavities: Figure 6a when there is no obstruction (prior art); Figure 6b shows the case with a discontinuous obstruction (a short wall perpendicular to the flow of the cooling fluid); Fig. 6c shows a case with a circular column, Fig. 6d shows a case with a V shape, and Fig. 6e shows a case with a zigzag channel; Fig. 6f shows the case where there are continuous obstacles (six adjacent spiral cooling channels formed by continuous obstacles forming the walls of the channels). The distance between the cooling fluid and the working surface of the punch is the same in all embodiments.

7 shows the surface temperature of various examples. It is clear that all embodiments according to the present invention provide a very homogeneous temperature profile along the length of the punch (about 40 to about 110 mm). The prior art shows significantly higher punch surface temperatures, and shows the improvements that the present invention can provide with respect to punch surface temperatures. Regardless of the direction of flow of the cooling fluid in the channel (distal end to proximal unit, proximal end to distal end or in the case of mixing), the lowest surface temperature is achieved with a continuous obstruction forming a helical channel. All embodiments of the present invention represent significant improvements over the prior art.

8 shows the effect of these low surface temperatures. Closed circles represent temperatures during can body production at a rate of 165 rounds per minute using a prior art annular internal cavity with no obstructions. The triangles represent the punch temperature at the same production rate and the same boundary conditions for the embodiment with six adjacent spiral cooling channels, reaching a steady state temperature of about 65°C compared to 95°C for the prior art punch. This means that production rates can be increased. In this example, the production rate is increased by 70% to 280 cans per minute, which results in a maximum punch temperature of less than 90°C, which is still lower than the prior art situation at much lower production rates. No scuffing or abrasion damage was observed in the cans made at the increased production rate according to the method of the present invention.

The result of the discrete barrier is only slightly less favorable than that of the continuous barrier, but allows for a marked improvement in surface temperature control and a related production rate improvement of around 60-65%.

Claims (14)

A method for producing a can body comprising a base and a tubular body for a two-piece can from a laminated metal sheet by deep-drawing and wall-ironing, comprising:
Here, a disk is produced from the laminated metal plate, the disk is deep-drawn into a cup, and then the cup is re-drawn and then the re-drawn cup is formed into a can-body by wall-ironing, wherein The wall-ironing is effected in a single stroke by punching the redrawn cup through one or more wall-ironing rings by means of an internally cooled punch assembly, wherein the punch assembly:

ram (14);

A punch (1), wherein the punch (1) is preferably removably attached to the ram, the punch assembly being between a position (15a) near the distal end of the punch and a position (15b) near the proximal end of the punch. a punch (1) comprising an internal annular cavity (15) below the surface of the punch; and

a plurality of cooling fluid inlets (16) for supplying cooling fluid into the inner annular cavity and a plurality of cooling fluid outlets (17) for removing the cooling fluid from the inner annular cavity, wherein the inner annular cavity has the punch a plurality of cooling fluid inlets (16) and a plurality of cooling fluid outlets (17) provided with means for improving the internal cooling efficiency of the

wherein the means for improving the internal cooling efficiency of the punch comprises a larger cooling surface for extracting heat from the punch and for increasing the turbulence of the cooling fluid while moving from the cooling fluid inlet to the cooling fluid outlet. comprising an obstruction (18) within the inner annular cavity to provide, said obstruction:
- consists of discontinuous obstacles 18, such as V-shapes, cylinders, discontinuous walls or discontinuous zigzag walls, or
- a plurality of adjacent helical wall-shaped continuous obstacles (18) defining a plurality of helical cooling channels in the inner annular cavity for conducting the cooling fluid from the cooling fluid inlet to the cooling fluid outlet,

wherein the ram includes means for supplying cooling fluid to the cooling fluid inlet and removing cooling fluid from the cooling fluid outlet;
Efficient internal cooling of the punch during production of the can body prevents wear damage or scuffing of the laminate layer on the tubular body of the can body, wherein
a. The cooling fluid inlets are arranged closer to the distal end of the punch and the cooling fluid outlets are arranged closer to the proximal end of the punch, preferably the inlets and outlets are arranged in a regular pattern around the circumference of the punch. arranged in a pattern, or
b. The cooling fluid inlets are arranged closer to the proximal end of the punch and the cooling fluid outlets are arranged closer to the distal end of the punch, preferably the inlets and outlets are arranged in a regular pattern around the circumference of the punch. arranged in a pattern, or
c. Cooling fluid inlets of some of the spiral cooling channels are arranged closer to the distal end of the punch, corresponding cooling fluid outlets are arranged closer to the proximal end of the punch, and cooling fluid inlets of other spiral cooling channels are arranged closer to the proximal end of the punch. are arranged closer to the proximal end of the punch, and corresponding cooling fluid outlets are arranged closer to the distal end of the punch, so that some of the spiral cooling channels direct cooling fluid from the distal end of the punch. to the proximal end and other cooling channels conduct cooling fluid from the proximal end to the distal end of the punch, preferably the direction of the cooling fluid alternates from one spiral cooling channel to an adjacent spiral cooling channel; , preferably wherein the inlets and outlets are arranged in a regular pattern around the circumference of the punch. According to claim 1,
The punch comprises at least 3 contiguous helical cooling channels, preferably at least 4 contiguous helical cooling channels, more preferably at least 5 contiguous helical cooling channels, and even more preferably at least 6 contiguous helical cooling channels. A method of manufacturing a can body comprising one or more contiguous spiral cooling channels. According to claim 1 or 2,
wherein each spiral cooling channel is provided with its own cooling fluid inlet and its own cooling fluid outlet. According to any one of claims 1 to 3,
wherein the redrawing ring and the one or more ironing rings also have internal cooling channels, wherein the internal cooling channels cool an outer laminate layer of the can body during the deep drawing and wall-iring. method. According to any one of claims 1 to 4,
The temperature of the punch assembly is controlled by a temperature control unit,
Here, the temperature control unit may include a method of adjusting the production speed of the can body; a manner of adjusting the flow rate of the cooling fluid entering the inner annular cavity; and adjusting the temperature of the cooling fluid entering the inner annular cavity, thereby controlling the temperature of the punch. An internally cooled punch assembly for use in the method according to any one of claims 1 to 4, said punch assembly comprising:

ram (14);

A punch (1), wherein the punch (1) is preferably removably attached to the ram, the punch assembly being between a position (15a) near the distal end of the punch and a position (15b) near the proximal end of the punch. a punch (1) comprising an internal annular cavity (15) below the surface of the punch; and

a plurality of cooling fluid inlets (16) for supplying cooling fluid into the inner annular cavity and a plurality of cooling fluid outlets (17) for removing the cooling fluid from the inner annular cavity, wherein the inner annular cavity has the punch a plurality of cooling fluid inlets (16) and a plurality of cooling fluid outlets (17) provided with means for improving the internal cooling efficiency of the

wherein the means for improving the internal cooling efficiency of the punch comprises a larger cooling surface for extracting heat from the punch and for increasing the turbulence of the cooling fluid while moving from the cooling fluid inlet to the cooling fluid outlet. comprising an obstruction (18) within the inner annular cavity to provide, said obstruction:
- consists of discontinuous obstacles 18, such as V-shapes, cylinders, discontinuous walls or discontinuous zigzag walls, or
- a plurality of adjacent helical wall-shaped continuous obstacles (18) defining a plurality of helical cooling channels in the inner annular cavity for conducting the cooling fluid from the cooling fluid inlet to the cooling fluid outlet,

wherein the ram includes means for supplying cooling fluid to the cooling fluid inlet and removing cooling fluid from the cooling fluid outlet;
Efficient internal cooling of the punch during production of the can body prevents wear damage or scuffing of the laminate layer on the tubular body of the can body, wherein
a. The cooling fluid inlets are arranged closer to the distal end of the punch and the cooling fluid outlets are arranged closer to the proximal end of the punch, preferably the inlets and outlets are arranged in a regular pattern around the circumference of the punch. arranged in a pattern, or
b. The cooling fluid inlets are arranged closer to the proximal end of the punch and the cooling fluid outlets are arranged closer to the distal end of the punch, preferably the inlets and outlets are arranged in a regular pattern around the circumference of the punch. arranged in a pattern, or
c. Cooling fluid inlets of some of the spiral cooling channels are arranged closer to the distal end of the punch, corresponding cooling fluid outlets are arranged closer to the proximal end of the punch, and cooling fluid inlets of other spiral cooling channels are arranged closer to the proximal end of the punch. are arranged closer to the proximal end of the punch, and corresponding cooling fluid outlets are arranged closer to the distal end of the punch, so that some of the spiral cooling channels direct cooling fluid from the distal end of the punch. to the proximal end and other cooling channels conduct cooling fluid from the proximal end to the distal end of the punch, preferably the direction of the cooling fluid alternates from one spiral cooling channel to an adjacent spiral cooling channel; , preferably wherein the inlets and outlets are arranged in a regular pattern around the circumference of the punch. According to claim 6,
wherein the punch (1) comprising the obstacle or the internal annular cavity (15) with the plurality of adjacent spiral cooling channels is a product of additive manufacturing. According to claim 7,
The punch (1) comprises a punch sleeve (19) and an insert (20), wherein the punch sleeve (19) and insert (20), when assembled, the inner annular ball conductor (15) with the obstacle (18). ) Forming a punch (1) having a punch assembly. According to claim 8,
wherein the insert (20) with the obstruction (18) is a product of additive manufacturing, wherein the insert (20) preferably further comprises a cooling fluid inlet (16) and a cooling fluid outlet (17). According to claim 9,
The material of the insert (20) is machined tool steel, wherein the obstruction (18) is machined into the insert, which preferably provides the cooling fluid inlet (16) and the cooling fluid outlet (17). Further comprising, a punch assembly. The method of any one of claims 6 to 10,
The plurality of successive obstacles forming the helical cooling channels run between a position 15a near the distal end of the punch and a position 15b near the proximal end of the punch, wherein the helical cooling channels form the helical cooling channels of the punch. Running below the surface, preferably each helical cooling channel is provided with a self-cooling fluid inlet 16 and a self-cooling fluid outlet 17, said punches being at least three, preferably at least four, more preferably at least four. comprises at least 5, even more preferably 6 contiguous helical cooling channels. The method of any one of claims 6 to 10,
The plurality of continuous obstacles forming the helical cooling channels run between a position (15a) near the proximal end of the punch and a position (15b) near the distal end of the punch, wherein the helical cooling channels are Running below the surface of the punch, preferably each spiral cooling channel is provided with a self-cooling fluid inlet 16 and a self-cooling fluid outlet 17, said punch having at least three, preferably at least four, more A punch assembly comprising preferably at least 5, even more preferably at least 6 contiguous helical cooling channels. According to any one of claims 6 to 12,
The temperature of the punch assembly is controlled by a temperature control unit, wherein the temperature control unit adjusts the production speed of the can body, the flow rate of the cooling fluid entering the inner annular cavity, and the inner annular cavity. wherein the punch assembly is capable of controlling the temperature of the punch by at least one of adjusting the temperature of the cooling fluid entering the punch assembly. A can body produced by the method according to any one of claims 1 to 5.

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