CAN MANUFACTURING METHOD AND DEVICE

Abstract

To provide a can manufacturing method performing air assist capable of smoothly pulling out a punch from a processed can by appropriately performing air assist. Provided is a can manufacturing method including drawing and/or drawing-and-ironing using a press machine, the method including stripping that includes removing a punch from a can after the drawing and/or the drawing-and-ironing. In the stripping, air is blown out from an air blowing port at a tip end of the punch to perform air assist of assisting extraction of the punch. In the air assist, a pressure of the air and/or a blowing timing of the air is adjusted for each shot to a pressure and/or a blowing timing according to a condition of the shot.

Description

TECHNICAL FIELD

The disclosure relates to a method and device for manufacturing metal cans by drawing and/or drawing-and-ironing using a press machine.

BACKGROUND

Conventionally, in drawing of a metal can using a press machine, there is known a technique of performing air assist in which assist air is supplied to a space between a tip of a punch and a bottom portion of the can in order to reduce a negative pressure generated between the can bottom portion and the punch tip portion when the punch is pulled out from the can after drawing and/or drawing-and-ironing of the metal can. (see JP 2021-70034 A, JP H9-271870 A, and JP Translation of PCT International Application 2019-525844 A)

SUMMARY

In a case where a metal can is manufactured by drawing using a press machine, when the metal can is drawn and/or drawn and ironed by a punch and then the punch is pulled out from the can, the processed can and the punch are in close contact with each other and the punch is pulled out at a high speed, and thus a negative pressure is generated in the space between the can bottom portion and the punch tip portion and the punch cannot be pulled out from the can. Then, the can is pressed by a stripper and the punch is pulled out, but the negative pressure generated in the space between the can bottom portion and the punch tip portion is not resolved. Therefore, air is blown out from the tip of the punch to resolve the negative pressure, thereby performing air assist to smoothly pull out the punch. (See FIGS. 1A to 1D)

However, if the air is not properly blown out, the punch may not be normally pulled out. For example, if the air blow is weak, the negative pressure generated in the space between the can bottom portion and the punch tip portion cannot be resolved and the can is crushed (see FIG. 4A), whereas if the air blow is strong, when the punch is pulled out, the can is blown off and collides with the surrounding structure such as the die (see FIG. 4B).

The disclosure has been proposed in order to solve the problem that the punch cannot be normally pulled out in some cases, and an object of the disclosure is to provide a method and a device for manufacturing a can in which air assist is performed so that the punch can be smoothly pulled out from the processed can by appropriately performing air assist.

In order to solve such problems, a can manufacturing method according to the disclosure has the following configuration.

A can manufacturing method including drawing and/or drawing-and-ironing using a press machine, the method including stripping that includes removing a punch from a can after the drawing and/or the drawing-and-ironing, wherein in the stripping, air is blown out from an air blowing port at a tip end of the punch to perform air assist of assisting extraction of the punch, and in the air assist, a pressure of the air and/or a blowing timing of the air is adjusted for each shot to a pressure and/or a blowing timing according to a condition of the shot.

A can manufacturing device according to the disclosure has the following configuration. A can manufacturing device for manufacturing cans using drawing and/or drawing-and-ironing, the device including a punch, a stripper, and a controller, wherein the punch includes an air blowing port configured to blow air at a tip end thereof, and the controller performs air blowing control of blowing air from the air blowing port while the stripper is engaged with an end portion of a can and the punch is being removed from the can, and in the air blowing control, a pressure of the air and/or a blowing timing of the air is adjusted for each shot to a pressure and/or a blowing timing according to a condition of the shot.

The disclosure can provide a method and a device for manufacturing cans in which a punch can be smoothly pulled out from a processed can by appropriately adjusting air pressure and/or air blowing timing in air assist.

BRIEF DESCRIPTION OF DRAWINGS

FIGS. 1A to 1D are diagrams illustrating air assist according to an embodiment of the disclosure.

FIG. 2 is a diagram illustrating an example of air pressure setting in a press machine according to an embodiment of the disclosure.

FIGS. 3A and 3B are diagrams illustrating an example of setting of air blowing timing in the press machine according to the embodiment of the disclosure, in which FIG. 3A is a table of timing correction amounts and FIG. 3B is a graph thereof.

FIGS. 4A and 4B are diagrams for explaining the problems to be solved by the disclosure.

DESCRIPTION OF EMBODIMENTS

Hereinafter, embodiments of the disclosure will be described with reference to the drawings. In the following description, the same reference symbols in different drawings denote elements having the same function, and redundant descriptions with regard to each drawing will be omitted as appropriate.

Hereinafter, embodiments of the disclosure will be described with reference to the drawings.

EMBODIMENTS

Hereinafter, a can manufactured by drawing and/or drawing-and-ironing using a press machine in the present embodiment is, for example, a can made of aluminum or steel mainly used for a beverage can which is so-called DI can or a resin-coated can, and is formed into a can by drawing-and-ironing an intermediate product formed into a cup shape using a body maker as a press machine.

Air Assist

FIGS. 1A to 1D are diagrams illustrating air assist in a stripping step according to the present embodiment.

It is a known technique described in JP 2021-70034 A, JP H9-271870 A, and JP Translation of PCT International Application 2019-525844 A that a body maker performs drawing-and-ironing on an intermediate product formed into a cup shape by a punch 2 and a plurality of dies (the dies are not illustrated) and finally forms the shape of a can bottom portion 11.

FIG. 1A illustrates a state in which forming of a can 1 by the punch 2 is completed.

After the forming of the can 1 is completed, a stripping step is performed in which the punch is pulled out from the can after the forming.

As illustrated in FIG. 1B, after the can 1 is formed, the punch 2 is pulled out from the can 1, but since an outer surface of the punch 2 and an inner surface of the can 1 are almost in close contact with each other and air 5 is not supplied to a space 4 between a can bottom portion 11 and a punch tip portion 21, when the punch 2 is pulled, the can 1 is moved together with the punch 2. Then, the upper end portion of the can 1 is engaged with a stripper 3.

As illustrated in FIG. 1C, when the upper end portion of the can 1 is engaged with the stripper 3, the can 1 is fixed, and thus the punch 2 is pulled out from the can 1. At this time, the air 5 is blown out from an air blowing port 22 provided in the punch tip portion 21, and the air 5 is supplied to the space 4 between the can bottom portion 11 and the punch tip portion 21 to assist the removal of the punch 2. Therefore, negative pressure is not generated between the can bottom portion 11 and the punch tip portion 21, and the punch 2 is pulled out from the can 1 by the action of the stripper 3.

Then, as illustrated in FIG. 1D, the punch 2 is removed from the can 1, and the blowing of the air 5 is also stopped.

Air Blowing Control (Operation Speed)

If the blown-out air 5 were not blown out at an appropriate pressure and at an appropriate timing, problems as illustrated in FIGS. 4A and 4B would occur. Thus, in the air assist, air blowing control is performed in which the pressure and blowing timing of the air are controlled by a controller in the air blowing.

In general, a body maker used for forming cans is not always operated at a constant speed, but the operation speed varies depending on various conditions or the like for the cans to be manufactured.

Even in the case of manufacturing cans of a specific type, control is performed by a controller so that manufacturing is performed at a low operation speed at the start of manufacturing, the operation speed is gradually increased, and when the operation speed reaches a predetermined operation speed, the operation is continued at the predetermined operation speed.

Even in the continuous operation state, there is a case where the operation speed of the body maker is appropriately increased or decreased in accordance with the operation state of the downstream step.

At a low operation speed, the speed at which the punch 2 is pulled out from the can 1 is also low, and at a high operation speed, the speed at which the punch 2 is pulled out from the can 1 is also high. Then, as for the speed at which the space 4 between the can bottom portion 11 and the punch tip portion 21 expands, similarly, the speed at which the space 4 expands is low at a low operation speed, and the speed at which the space 4 expands is high at a high operation speed.

Air Pressure Control (Operation Speed)

When the speed at which the space 4 expands is different, it is necessary to change the blowing rate of the air 5 blown out from the air blowing port 22 of the punch 2. That is, when the speed at which the space 4 expands increases, it is necessary to increase the supply rate of the air 5 per unit time.

The supply rate of the air 5 per unit time is increased by increasing the pressure at which the air 5 is supplied.

As described above, when the operation speed of the body maker is increased, the pressure for supplying the air 5 is increased.

Therefore, the relationship between the operation speed of the body maker and the air pressure is defined in advance, and each time a can is molded (each shot), the air pressure is controlled (operation speed) by the controller so that the air pressure is in accordance with the operation speed at the time of the shot.

For example, control is performed in accordance with the relationship shown in the graph of FIG. 2. The operation speed at the start of the operation is 100 spm (shot/minute) and the air pressure at that time is 100 kPa, and thereafter the operation speed is gradually increased to 140 kPa at 200 spm, 170 kPa at 300 spm, and 180 kPa at 400 spm to press the can 1.

The pressure of the air can be controlled using, for example, a known electropneumatic regulator.

Note that the operation speed, the air pressure, and the combination thereof may be appropriately set to optimum values in consideration of the type and constituent elements of the press machine, the type and size of the can to be manufactured, the manufacturing procedure, and the like, and are not limited to those shown in the graph of FIG. 2. Note that the relationship between the operation speed and the air pressure is not limited to a broken line as shown in the graph of FIG. 2, but may be a straight line, a curved line, or a combination thereof.

Air Blowing Timing Control (Operation Speed)

Since the air 5 is not always supplied but is supplied when the punch 2 is pulled out from the can 1, an opening/closing valve (not illustrated), for example, an electromagnetic valve is provided in a supply path of the air 5 to the air blowing port 22 of the punch 2, and the opening/closing valve controls the operation timing (air blowing timing) of the opening/closing valve so that the air 5 is supplied from the air blowing port 22 in accordance with the timing when the punch 2 is pulled out from the can 1.

The opening/closing valve is provided outside the punch 2, and there is a predetermined distance from the opening/closing valve to the air blowing port 22. Although the air blown in the previous shot remains between the opening/closing valve and the air blowing port 22, there is a time delay from the operation timing of the opening/closing valve (air blowing timing) until the air 5 is actually blown from the air blowing port 22 and the air 5 is sufficiently supplied to the space 4 between the can bottom portion 11 and the punch tip portion 21. Note that there is a slight time delay also in the operation of the opening/closing valve itself.

As described above, the operation speed of the body maker changes, and the influence of the time delay from the operation timing of the opening/closing valve (air blowing timing) varies depending on the operation speed of the body maker.

Since the time delay of the air supply does not change even when the operation speed of the body maker changes, it is necessary to set the operation timing of the opening/closing valve (air blowing timing) earlier when the operation speed increases.

Therefore, the relationship between the operation speed of the body maker and the operation timing of the opening/closing valve (air blowing timing) is defined in advance, and the controller controls the operation timing of the opening/closing valve (air blowing timing) in accordance with the operation speed.

The time delay itself from the operation timing of the opening/closing valve (air blowing timing) changes depending on the pressure of the blown air. When the air pressure is high, the time delay tends to decrease, and when the air pressure is low, the time delay tends to increase.

Therefore, the relationship between the air pressure and the operation timing of the opening/closing valve (air blowing timing) is defined in advance, and each time a can is formed (each shot), the controller controls the operation timing of the opening/closing valve (air blowing timing) in accordance with the air pressure at the time of the shot.

As described above, for each shot, the operation timing of the opening/closing valve (air blowing timing) is controlled in accordance with the operation speed of the body maker or the pressure of the blown air at the time of the shot.

When the operation timing of the opening/closing valve (air blowing timing) is controlled for each shot in accordance with the operation speed of the body maker and the pressure of the blown air at the time of the shot, it can be controlled to a more appropriate timing.

Control Example of Air Blowing Timing Control (Operation Speed)

For example, a known electronic cam switch with an automatic advance function is used to control the operation timing (air blowing timing) of the opening/closing valve. In the electronic cam switch, a detector that detects a rotation angle (0° to 360°) is installed on a rotation shaft, and a switch signal corresponding to an output of an angle signal corresponding to a predetermined angle (°) from the detector is output. The automatic advance function can set an advance correction angle (°) according to the rotation speed of the rotation shaft, and outputs a switch signal according to an output of an angle signal corresponding to an angle obtained by advancing the set advance correction angle (°) from a predetermined angle (°) according to the rotation speed. The opening/closing control of the opening/closing valve is performed by the switch signal output from the electronic cam switch. The detector is mounted on a rotation shaft for driving the punch 2. The rotation shaft performs one shot in one rotation.

For example, it is assumed that the angle of the rotation shaft at which the control for opening the opening/closing valve is performed (the operation timing of the opening/closing valve (the air blowing timing)) is 180° at the reference operation speed (0 spm) and air pressure (170 kPa). When the operation speed (rotation speed of the rotation shaft) becomes faster, the influence of the time delay becomes larger. The operation timing (air blowing timing) of the opening/closing valve due to this influence, that is, the delay conversion angle (°) which is the adjustment amount of the rotation shaft is determined corresponding to the rotation speed. The rotation speed and the delay conversion angle are set to the automatic advance function of the electronic cam switch as the speed of the rotation shaft and the advance correction angle.

The setting of the speed of the rotation shaft and the advance correction angle in the automatic advance function is also performed at other air pressures, for example, 140 kPa.

FIG. 3A shows a table of the operation speed (rotation speed of the rotation shaft) and the delay conversion angle (advance correction angle). Note that “Corrected ON angle) (°” in FIG. 3A is a numerical value obtained by subtracting the delay conversion angle (advance correction angle) from 180° which is a reference angle for performing control to open the opening/closing valve. FIG. 3B is a graph of the table of FIG. 3A.

As illustrated in FIGS. 3A and 3B, since the delay conversion angle increases and the corrected ON angle decreases as the operation speed increases, it can be seen that the angle of the rotation shaft that performs control to open the opening/closing valve (the operation timing of the opening/closing valve (air blowing timing)) becomes smaller than the reference angle of 180°, that is, the timing is advanced.

It can also be seen that the delay conversion angle increases as the air pressure decreases.

Thus, the operation timing of the opening/closing valve (air blowing timing) is controlled in accordance with the operation speed of the body maker and the pressure of the blown air.

Note that the operation speed, the air pressure, the delay conversion angle, and the combination thereof may be appropriately set to optimum values in consideration of the type and constituent elements of the press machine, the type and size of the can to be manufactured, the manufacturing procedure, and the like, and are not limited to those shown in the table and graph of FIGS. 3A and 3B. The operation speed, the air pressure, the delay conversion angle, and the combination thereof are not limited to the broken line as shown in the graph of FIG. 3B, but may be a straight line, a curved line, or a combination thereof.

Composite Control (Operation Speed)

As described above, the air pressure or the air blowing timing is controlled to the optimum value for each shot according to the operation speed of the press machine. However, composite control (operation speed) may be performed in which the air pressure and the air blowing timing are controlled to the optimum values.

In the composite control (operation speed), it is preferable to set the air pressure and the air blowing timing in consideration of the synergistic effect of the air pressure control and the air blowing control, instead of simply performing the control with the set values of the air pressure control (operation speed) and the air blowing timing control (operation speed), separately.

Air Blowing Control (Leading Can)

In the shot when the body maker starts the operation and forms the first can (leading can) after the start of the operation, since air with a sufficiently high pressure does not exist in an air supply path 23 leading to the air blowing port 22, sufficient air is not supplied to the space 4 between the can bottom portion 11 and the punch tip portion 21.

Then, in the shot for forming the leading can, even when forming is performed under the same conditions as in the shot for forming another can, for example, the second can, a problem as illustrated in FIG. 4A occurs.

Air Pressure Control (Leading Can)

In the shot when forming the leading can, sufficient air is supplied to the space 4 by performing air pressure control (leading can) for supplying air having a pressure higher than the air pressure at the time of the shot for forming the second can, for example, in which other processing conditions such as the operation speed are the same.

For example, when the operation speed at the start of operation is 100 spm, the air pressure at that time is set to 100 kPa as shown in FIG. 2, but in the shot for forming the leading can, the air pressure is set to a high pressure of 140 kPa.

Note that the pressure of the air in the shot for forming the leading can may be appropriately set to an optimum value in consideration of the type and constituent elements of the press machine, the type and size of the can to be manufactured, the manufacturing procedure, the pressure of the air when the can is not the leading can, and the like.

Air Blowing Timing Control (Leading Can)

In the shot for forming the leading can, sufficient air is supplied to the space 4 by performing air blowing timing control (leading can) for supplying air at an air blowing timing earlier than the air blowing timing at the time of the shot for forming the second can, for example, in which other processing conditions such as the operation speed are the same.

For example, assuming that the delay conversion angle is 14° when the air pressure at the start of the operation is 100 kPa and the operation speed is 100 spm, in the shot for forming the leading can, the delay conversion angle is set to 16°, which is an early air blowing timing. Note that the air blowing timing in the shot for forming the leading can may be appropriately set to an optimum value in consideration of the type and constituent elements of the press machine, the type and size of the can to be manufactured, the manufacturing procedure, the air blowing timing when the can is not the leading can, and the like.

Composite Control (Leading Can)

As described above, the air pressure or the air blowing timing is controlled to the optimum value for each shot for forming the leading can. However, composite control (leading can) for controlling the air pressure and the air blowing timing to the optimum values may be performed.

In the composite control (leading can), it is preferable to set the air pressure and the air blowing timing in consideration of the synergistic effect of the air pressure control and the air blowing control, instead of simply performing control with the set values of the air pressure control (leading can) and the air blowing timing control (leading can), separately.

Although the embodiments according to the disclosure have been described in detail with reference to the drawings, the specific configurations are not limited to these embodiments, and design changes and the like without departing from the gist of the disclosure are also included in the disclosure.

The above-described embodiments can be combined with each other by applying techniques to each other as long as there is no particular contradiction or problem in the purpose, configuration, and the like.

While preferred embodiments of the disclosure have been described above, it is to be understood that variations and modifications will be apparent to those skilled in the art without departing from the scope and spirit of the disclosure. The scope of the disclosure, therefore, is to be determined solely by the following claims.

Claims

1. A can manufacturing method including drawing and/or drawing-and-ironing using a press machine, the method comprising: stripping that includes removing a punch from a can after the drawing and/or the drawing-and-ironing, whereinin the stripping, air is blown out from an air blowing port at a tip end of the punch to perform air assist of assisting extraction of the punch, andin the air assist, a pressure of the air and/or a blowing timing of the air is adjusted for each shot to a pressure and/or a blowing timing according to a condition of the shot.

2. The can manufacturing method according to claim 1, wherein the pressure of the air is adjusted to a pressure corresponding to an operation speed during the shot.

3. The can manufacturing method according to claim 1, wherein when the shot is a shot for a first can after a start of an operation, the pressure of the air is adjusted to be higher than a pressure during a shot where other conditions of the shot are the same, and/or the blowing timing of the air is adjusted to be earlier than a blowing timing during a shot where the other conditions of the shot are the same.

4. The can manufacturing method according to claim 1, wherein the blowing timing of the air is adjusted to a timing corresponding to an operation speed and/or the pressure of the air during the shot.

5. The can manufacturing method according to claim 1, wherein the press machine is a body maker.

6. A can manufacturing device for manufacturing cans using drawing and/or drawing-and-ironing, the device comprising: a punch; a stripper; and a controller, whereinthe punch includes an air blowing port configured to blow air at a tip end thereof, andthe controller performs air blowing control of blowing air from the air blowing port while the stripper is engaged with an end portion of a can and the punch is being removed from the can, andin the air blowing control, a pressure of the air and/or a blowing timing of the air is adjusted for each shot to a pressure and/or a blowing timing according to a condition of the shot.

7. The can manufacturing device according to claim 6, wherein the controller adjusts the pressure of the air to a pressure corresponding to an operation speed during the shot.

8. The can manufacturing device according to claim 6, wherein when the shot is a shot for a first can after a start of an operation, the controller adjusts the pressure of the air to be higher than a pressure during a shot with the same other conditions of the shot, and/or adjusts the blowing timing of the air to be earlier than a blowing timing during a shot where other conditions of the shot are the same.

9. The can manufacturing device according to claim 6, wherein the controller adjusts the blowing timing of the air to a timing corresponding to an operation speed and/or the pressure of the air during the shot.

10. The can manufacturing method according to claim 6, wherein the manufacturing device is a body maker.