EXTRUSION PRESS DEVICE AND EXTRUSION PRESS METHOD

Abstract

An extrusion press device according to the present invention includes: an extrusion unit that includes a container configured to store an extrusion material and an end platen configured to support a die-from which the extrusion material is extruded; and a control unit configured to control operation of the extrusion unit, including container sealing force that presses the container against the die. The control unit performs control to apply complementary pressure corresponding to reduced container sealing force that is increased along with progression of extrusion, to the container in a direction of the extrusion during a period from start to completion of the extrusion.

Description

TECHNICAL FIELD

The present invention relates to an extrusion press device and an extrusion press method used for extrusion molding of a metal material such as an aluminum alloy.

BACKGROUND ART

In an extrusion press device that extrudes and molds an extrusion material called a billet that is made of a metal material such as aluminum and an alloy material thereof has an extrusion stem attached, through a main crosshead, at a front end part of a main ram of a main cylinder that is driven and advanced by hydraulic pressure. Extrusion molding by the extrusion press device includes an upset process and an extrusion process. In the upset process, in a state where a container is pressed against a die disposed on an end platen side, by a container cylinder and the like, the extrusion stem is advanced to cause the die to press the extrusion material stored in the container. In the extrusion process, the main ram is further advanced to cause the die to press the extrusion material by the extrusion stem, and a predetermined product is extruded and molded from the die.

In such extrusion molding by the extrusion press device, force pressing the container against the die disposed on the end platen side, by the container cylinder and the like is referred to as container sealing force. The container sealing force is force applied to the container by a hydraulic cylinder such as the container cylinder during the extrusion process in order to prevent a “bursting phenomenon” when the extrusion material stored in the container is pressed by the extrusion stem. The “bursting phenomenon” is a phenomenon in which the extrusion material is extruded from a gap between an end surface of the die and a front end surface of the container.

For example, Patent Literature 1 discloses an equal-pressure extrusion control method that controls the container sealing force acting on the die during the extrusion process to be constant during a period from start to completion of the extrusion.

CITATION LIST

Patent Literature

• Patent Literature 1: JP 2013-035036 A

SUMMARY OF INVENTION

Technical Problem

According to the equal-pressure extrusion control method disclosed in Patent Literature 1, it is possible to prevent the “bursting phenomenon” that often occurs in a second half of the extrusion process through prevention of reduction of the container sealing force along with progression of the extrusion process.

The equal-pressure extrusion control method disclosed in Patent Literature 1, however, decreases the container sealing force acting on the die by pressing a container holder in a direction opposite to the extrusion during a period from the start to the middle of the extrusion, namely, in a first half of the extrusion process. The equal-pressure control method disclosed in Patent Literature 1 controls the container sealing force acting on the die during the extrusion process to be constant during the period from the start to the end of the extrusion through the decrease of the container sealing force.

As described above, in the Patent Literature 1, the die is pressed in the direction opposite to the extrusion in the first half of the extrusion process. Therefore, reaction force of extruding force acting between the end platen and a main cylinder housing coupled by, for example, a tie rod is continuously reduced from the start of the extrusion. When the reaction force of the extruding force is continuously reduced, a deformation amount of the end platen receiving the reaction force of the extruding force through the die is reduced, and the deformation amount influences a deformation amount of the die. The deformation of the end platen is deflection mainly caused by curved deformation, and the deformation of the die is deflection caused by compression and curvature in a longitudinal direction. These deflection adversely affects accuracy of an extruded product.

The present invention is made in consideration of the above-described issues, and an object of the present invention is to provide an extrusion press device and an extrusion press method that make it possible to suppress deflection of an end platen, a die, and the like while preventing a “bursting phenomenon”.

Solution to Problem

An extrusion press device according to the present invention includes: an extrusion unit including a container configured to store an extrusion material, and an end platen configured to support a die from which the extrusion material is extruded; and a control unit configured to control operation of the extrusion unit. A target of the control by the control unit includes container sealing force that presses the container against the die.

The control unit according to the present invention performs control to apply complementary pressure corresponding to reduced container sealing force that is increased along with progression of extrusion, to the container in a direction of the extrusion during a period from start to completion of the extrusion.

The control unit according to the present invention preferably controls application of the complementary pressure to maintain reference container sealing force that is the container sealing force at the start of the extrusion, during the period from the start to the completion of the extrusion.

The control unit according to the present invention preferably handles container sealing force calculated at the start of the extrusion, as the reference container sealing force.

The control unit according to the present invention preferably calculates the reduced container sealing force as a difference between container sealing force during the extrusion and the reference container sealing force.

The control unit according to the present invention preferably performs control to apply, as the complementary pressure, force of 20% or more and 30% or less of maximum actual extruding force at the start of the extrusion, to the container.

The extrusion unit according to the present invention preferably includes a container cylinder that advances the container to approach the end platen or retreats the container to separate from the end platen.

The container cylinder preferably includes a first oil chamber and a second oil chamber that are arranged in a longitudinal direction X along the extrusion direction, and each of the first oil chamber and the second oil chamber preferably includes two divided oil chambers divided in the longitudinal direction X.

The control unit according to the present invention preferably includes an equal-pressure extrusion control hydraulic circuit that supplies hydraulic oil to one or both of the first oil chamber and the second oil chamber of the container cylinder when the container is advanced by the container cylinder. The equal-pressure extrusion control hydraulic circuit is independent of a hydraulic circuit to extrude the extrusion material.

The present invention provides an extrusion press method of extruding an extrusion material from a die while pressing a container against the die to apply container sealing force, the extrusion material being extruded from the die and being stored in the container.

In the extrusion press method according to the present invention, a difference between reference container sealing force and in-extrusion container sealing force is handled as reduced container sealing force. At this time, the reference container sealing force is container sealing force at start of extrusion in the extrusion press method that extrudes the extrusion material from the die while pressing the container against the die to apply the container sealing force, the extrusion material being extruded from the die and being stored in the container. Further, the in-extrusion container sealing force is the container sealing force during the extrusion.

In the extrusion press method according to the present invention, complementary pressure corresponding to the reduced container sealing force is applied to the container in a direction of the extrusion during a period from the start to completion of the extrusion.

In the extrusion press method according to the present invention, the complementary pressure is preferably applied to maintain the reference container sealing force at the start of the extrusion during the period from the start to the completion of the extrusion.

In the extrusion press method according to the present invention, the reference container sealing force and the in-extrusion container sealing force are preferably based on information detected at and after the start of the extrusion. Further, the reduced container sealing force and the complementary pressure are calculated during the extrusion, based on the detected reference container sealing force and the detected in-extrusion container sealing force.

Advantageous Effects of Invention

According to the present invention, the complementary pressure corresponding to the reduced container sealing force that is increased along with progression of the extrusion, is applied to the container in the extrusion direction during the period from the start to the completion of the extrusion. As a result, the extruding force propagating to the end platen through the die is maintained to be constant during the period from the start to the completion of the extrusion. Accordingly, the amount of deflection occurred on the end platen and the die caused by the extruding force is maintained in the state at the start of the extrusion, until the completion of the extrusion.

In addition, according to the present invention, control is performed to apply the complementary pressure corresponding to the container sealing force that is reduced along with progression of the extrusion, to the container in the extrusion direction during the period from the start to the completion of the extrusion. Applying the complementary pressure makes it possible to secure the container sealing force sufficient to prevent the “bursting phenomenon” during the period from the start to the completion of the extrusion.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic plan view of an extrusion press device according to a first embodiment.

FIG. 2 is a schematic front view of a main cylinder housing of the extrusion press device according to the first embodiment.

FIGS. 3A and 3B each are a schematic cross-sectional view of a container cylinder of the extrusion press device according to the first embodiment.

FIG. 4A is a partial enlarged view of FIG. 1 and illustrates force generated in elements of the extrusion press device, FIG. 4B is a graph illustrating variation of extruding force F and container sealing force f during an extrusion process, and FIG. 4C is a graph illustrating equal-pressure extrusion control according to the first embodiment.

FIG. 5 is a schematic hydraulic circuit diagram to perform an equal-pressure extrusion control method by the extrusion press device according to the first embodiment.

FIG. 6 is a flowchart illustrating a procedure to calculate various kinds of parameters according to the first embodiment.

FIG. 7A is a flowchart illustrating a procedure to set reference container sealing force, and FIG. 7B is a flowchart illustrating a procedure to calculate reduced container sealing force.

FIG. 8 is a schematic hydraulic circuit diagram to perform main-crosshead retreat control method by an extrusion press device according to a second embodiment.

DESCRIPTION OF EMBODIMENTS

An extrusion press device and an extrusion press method according to preferred embodiments of the present invention are described in detail below with reference to accompanying drawings. Note that the following embodiments do not limit the invention according to the scope of appended claims, and of combinations of features described in the embodiments are not necessarily essential for means for solving the problem of the invention.

First Embodiment

First, a main configuration of an extrusion press device 1 according to a first embodiment is described with reference to FIG. 1 and FIG. 2.

[Extrusion Unit 3 in Extrusion Press Device 1]

The extrusion press device 1 according to the first embodiment includes, as an extrusion unit 3, an end platen 10, a main cylinder housing 12, and a main cylinder 12A.

The end platen 10 supports a die 16 by a surface on a side facing the main cylinder housing 12. The main cylinder housing 12 is disposed so as to face the end platen 10, and is coupled with the end platen 10 by a plurality of tie rods 14. The main cylinder 12A is disposed at a substantially center of the main cylinder housing 12.

The extrusion press device 1 further includes, as the extrusion unit 3, a main crosshead 22 and a main ram 12B.

The main crosshead 22 is disposed between the end platen 10 and the main cylinder housing 12, and an extrusion stem 24 is disposed so as to protrude from a front end surface of the main crosshead 22. One end side of the main ram 12B is fixed to a rear end surface of the main crosshead 22, and the other end side is stored in the main cylinder 12A. The main ram 12B advances the main crosshead 22 to approach the end platen 10.

The extrusion press device 1 further includes, as the extrusion unit 3, a plurality of side cylinders 26, a container 18, and a plurality of container cylinders 28.

As illustrated in FIG. 2, the side cylinders 26 are disposed around the main cylinder 12A, and advance the main crosshead 22 to approach the end platen 10 or retreat the main crosshead 22 to separate from the end platen 10.

The container 18 is disposed between the end platen 10 and the main crosshead 22, and stores an extrusion material EM.

The container cylinders 28 advance the container 18 fixed to a container holder 19, to approach the end platen 10, or retreat the container 18 to separate from the end platen 10.

Note that, in the extrusion press device 1, a side on which the end platen 10 is disposed is defined as front, and a side on which the main cylinder housing 12 is disposed is defined as back. In FIG. 1, FIG. 3A, FIG. 3B, FIG. 5, and FIG. 8, front is denoted by (F), and back is denoted by (B). Further, the terms front and back include relative meanings. For example, it can be said that the main crosshead 22 is disposed on the back side of the container holder 19.

Further, in the extrusion press device 1, a longitudinal direction X is defined by arrows illustrated in FIG. 1, FIG. 3A, FIG. 3B, and FIG. 8. Further, an extrusion direction is defined by a direction illustrated by a left arrow out of the arrows representing the longitudinal direction X.

[Container Cylinder 28]

The container cylinders 28 include characteristic elements in the extrusion press device 1. More specifically, the container cylinders 28 are disposed in the main cylinder housing 12, and advance the container 18 from the main cylinder housing 12 side to press the container 18 against the die 16 disposed on the end platen 10 during an extrusion process.

Further, each of the container cylinders 28 has a so-called tandem structure. More specifically, as illustrated in FIG. 3A and FIG. 3B, each of the container cylinders 28 includes a plurality of oil chambers in the longitudinal direction X of a cylinder rod 28A. Each of the container cylinders 28 is characterized in that the cylinder rod 28A communicating with the oil chambers is provided with pistons slidable in the longitudinal direction X in the respective oil chambers, and two divided oil chambers divided in the longitudinal direction X by the piston are formed in each of the oil chambers. A specific configuration of one container cylinder 28 is described with reference to FIG. 3A and FIG. 3B. FIG. 3A illustrates a state where the cylinder rod 28A of the container cylinder 28 is retreated up to a retreat limit position, and FIG. 3B illustrates a state where the cylinder rod 28A of the container cylinder 28 is located at an intermediate position.

In the container cylinder 28, a first oil chamber 51 and a second oil chamber 61 are arranged in the longitudinal direction X in order from the container 18 (front F) side. The first oil chamber 51 and the second oil chamber 61 are partitioned by a coupling portion 71. The cylinder rod 28A communicating with both of the first oil chamber 51 and the second oil chamber 61 has a configuration in which a first rod 52 communicating with the first oil chamber 51 on the front side (F) and a second rod 62 communicating with the second oil chamber 61 on the back side (B) are coupled by a screwing structure or the like on the first oil chamber 51 side. The first oil chamber 51 on the front side (F) is provided in a first cylinder body 53 through which the first rod 52 penetrates. The second oil chamber 61 on the back side (B) is provided in a second cylinder body 63. Further, the first cylinder body 53 and the second cylinder body 63 are fixed to the coupling portion 71 such that an opening on the back side (B) of the first cylinder body 53 and an opening on the front side (F) of the second cylinder body 63 face each other. The second rod 62 communicating with the second oil chamber 61 penetrates through the coupling portion 71. As a result, the first oil chamber 51 and the second oil chamber 61 are provided as independent oil chambers.

On the other hand, a first piston 54 that divides the first oil chamber 51 into two sections in the longitudinal direction X is provided at a coupling part between the first rod 52 and the second rod 62 on the first oil chamber 51 side. Further, a second piston 64 that divides the second oil chamber 61 into two sections in the longitudinal direction X is provided at a back end of the second rod 62. The first piston 54 and the second piston 64 are attached to respective corresponding portions by a screwing structure or the like.

A seal fixing member 55 that fixes a sealing member and the like for the first rod 52 is attached to the front side (F) of the first cylinder body 53. Further, a closing member 65 that closes the opening on the back side (B) of the second cylinder body 63 and fixes a sealing member is attached to the opening.

As illustrated in FIG. 3B, in the container cylinder 28 having the above-described configuration, the first oil chamber 51 is divided into and referred to as a divided oil chamber 56A and a divided oil chamber 56B, and the second oil chamber 61 is divided into and referred to as a divided oil chamber 66A and a divided oil chamber 66B.

The divided oil chamber 56A occupies a front section of the two sections divided in the longitudinal direction X from the first oil chamber 51 by the first piston 54, namely, the front side (F) of the first piston 54. The divided oil chamber 56B occupies a back section of the first oil chamber 51, namely, a section between the first piston 54 and the coupling portion 71. Further, the divided oil chamber 66A occupies a front section of the two sections divided in the longitudinal direction X from the second oil chamber 61 by the second piston 64, namely, a section between the coupling portion 71 and the second piston 64. The divided oil chamber 66B occupies a back section of the second oil chamber 61, namely, a section between the second piston 64 and the closing member 65.

Hydraulic pipes P1, P2, P3, and P4 are connected to the divided sections of the first oil chamber 51 divided in the longitudinal direction X by the first piston 54 and the divided sections of the second oil chamber 61 divided in the longitudinal direction X by the second piston 64.

To advance and press the container 18, hydraulic oil is supplied to at least one of the divided oil chamber 56B and the divided oil chamber 66B through at least one of the hydraulic pipe P2 and the hydraulic pipe P4. To obtain large output, the hydraulic oil is supplied to both of the hydraulic pipe P2 and the hydraulic pipe P4. Further, to retreat the container 18, the hydraulic oil is supplied to at least one of the divided oil chamber 56A and the divided oil chamber 66A through at least one of the hydraulic pipe P1 and the hydraulic pipe P3. Likewise, to obtain large output, the hydraulic oil is supplied to both of the hydraulic pipe P1 and the hydraulic pipe P3.

Note that FIGS. 3A and 3B illustrate the example of the specific configuration of the container cylinder 28, and the configuration of the container cylinder 28 according to the present invention is not limited to the configuration illustrated in FIG. 3A and FIG. 3B. For example, as illustrated in FIG. 5, the present invention can adopt a single cylinder form in which one oil chamber is divided by one piston. Further, for simplification of the drawing, illustration of the sealing member, the screwing structure, and the fixing member (such as bolt) is omitted in FIG. 3A and FIG. 3B.

[Container Sealing Force]

Next, the container sealing force is described with reference to FIG. 4A to FIG. 4C.

As illustrated in FIG. 4A, container sealing force f that presses the container 18 against the die 16 is generated on a contact surface of the die 16 and the container 18.

During the extrusion process, when the extrusion material EM stored in the container 18 is pressed against the die 16 by the extrusion stem 24, the extrusion material EM is plastically deformed in a circumferential direction inside the container 18 by extruding force F applied to the extrusion material EM. An outer peripheral surface of the extrusion material EM comes into surface contact with an inner peripheral surface of the container 18 that stores the extrusion material EM. Therefore, frictional force Fb occurs between the outer peripheral surface of the extrusion material EM and the inner peripheral surface of the container 18 during the extrusion process. Accordingly, the extruding force F that is to be applied to the extrusion material EM by the extrusion stem 24 in an advancing direction approaching the end platen 10 is represented by a sum of necessary extrusion force Fa acting on the die 16 through the extrusion material EM and the frictional force Fb, namely, F=Fa+Fb.

The necessary extrusion force Fa is extrusion resistance force of the die 16 when the extrusion material EM is extruded and molded from the die 16 in a state with no frictional force Fb. Assuming that temperature of the extrusion material EM is not varied during the extrusion process, the necessary extrusion force Fa is substantially uniform during a period from the start to the completion of the extrusion.

On the other hand, the frictional force Fb is the largest at the start of the extrusion, and the frictional force at the start of the extrusion is referred to as the maximum frictional force Fbmax. This is because a contact area between the extrusion material EM and the container 18 is the largest at the start of the extrusion. The contact area has proportional relationship with a dimension in the longitudinal direction X of the extrusion material EM located inside the container 18, namely, an extrusion material length L.

The frictional force Fb is continuously reduced in proportion to reduction of the extrusion material length L along with progression of the extrusion process. Further, when the extrusion material length L becomes the minimum extrusion material length Lmin at the completion of the extrusion, the frictional force Fb becomes the minimum frictional force Fbmin.

Accordingly, as illustrated in FIG. 4B, the extruding force F (Fa Fbmax) at the start of the extrusion is reduced to Fa Fbmin at the completion of the extrusion. A lateral axis of FIG. 4B indicates the extrusion material length L of the extrusion material EM, and an origin corresponds to the maximum extrusion material length Lmax. The origin indicates start of the extrusion, and the extrusion material length L at this time is the maximum extrusion material length Lmax. Likewise, a vertical axis indicates the extruding force F.

In addition, as illustrated in FIG. 4A, reaction force Fb′ of the frictional force Fb between the extrusion material EM and the container 18 acts on the container 18 in a direction in which the container 18 is pressed against the die 16, namely, in the same direction as the container sealing force f. The reaction force Fb′ is typically about 30% of the maximum actual extruding force F, and at least the maximum reaction force Fbmax of the maximum frictional force Fbmax at the start of the extrusion is force sufficient as the container sealing force f preventing the “bursting phenomenon”. Accordingly, when the force lower than or equal to 30% or preferably higher than or equal to 20% of the maximum actual extruding force is applied as complementary pressure Pa to the container 18, it is possible to prevent the “bursting phenomenon”.

[Control Unit 5 of Extrusion Press Device 1]

Next, a hydraulic circuit to operate the extrusion press device 1 is described with reference to FIG. 5.

The extrusion press device 1 is provided with the hydraulic circuit including an equal-pressure extrusion control hydraulic circuit 84 that includes pressure detection means 81, an equal-pressure extrusion control hydraulic-oil supply source 82, and equal-pressure extrusion control pressure control means 83. The extrusion press device 1 is provided with a controller 85 controlling operation of the equal-pressure extrusion control hydraulic circuit 84 that includes the pressure detection means 81, the equal-pressure extrusion control hydraulic-oil supply source 82, and the equal-pressure extrusion control pressure control means 83.

The equal-pressure extrusion control hydraulic circuit 84 that includes the pressure detection means 81, the equal-pressure extrusion control hydraulic-oil supply source 82, and the equal-pressure extrusion control pressure control means 83, and the controller 85 configure a control unit 5.

In the following, the equal-pressure extrusion control hydraulic-oil supply source 82, and the equal-pressure extrusion control pressure control means 83, and the equal-pressure extrusion control hydraulic circuit 84 are respectively abbreviated to the hydraulic-oil supply source 82, the pressure control means 83, and the control hydraulic circuit 84.

The pressure detection means 81 detects pressure of the hydraulic oil inside the main cylinder 12A when the main crosshead 22 is advanced. The pressure detection means 81 further detects pressure of the hydraulic oil supplied to the main cylinder 12A. The pressure detection means 81 includes a pressure sensor such as a pressure pickup.

To advance the container 18, the hydraulic-oil supply source 82 supplies the hydraulic oil to one or both of the divided oil chamber 56B of the first oil chamber 51 and the divided oil chamber 66B of the second oil chamber 61 in each of the container cylinders 28. To retreat the container 18, the hydraulic-oil supply source 82 supplies the hydraulic oil to one or both of the divided oil chamber 56A of the first oil chamber 51 and the divided oil chamber 66A of the second oil chamber 61 in each of the container cylinders 28.

In the case of the container cylinders 28 based on the single cylinder illustrated in FIG. 5, when the hydraulic oil is supplied to the oil chamber 56A and the oil chamber 56B, a differential pressure circuit is configured. This makes it possible to increase the advance speed of the rod.

The hydraulic circuit having the above-described configuration is a hydraulic circuit that is dedicated to advance/retreat the container 18 and is independent of the hydraulic circuit from a main hydraulic-oil supply source. The hydraulic-oil supply source 82, however, is not used only for equal-pressure extrusion control during the extrusion process, and can be driven together with the main hydraulic-oil supply source at a time other than the extrusion process. In FIG. 3A and FIG. 3B, to simplify the hydraulic circuit, illustration of the main hydraulic-oil supply source and the hydraulic circuit from this supply source is omitted. The main hydraulic-oil supply source includes, for example, one or more hydraulic pumps. Note that, in the schematic hydraulic circuit diagram of FIG. 5, a symbol of a variable discharge hydraulic pump is illustrated as the hydraulic pump of the hydraulic-oil supply source 82; however, the hydraulic pump of the hydraulic-oil supply source 82 may be a hydraulic pump, the discharge amount of which is controlled through rotational speed control of a driving motor.

When the extrusion stem 24 is advanced to extrude the extrusion material EM stored in the container 18 from the die 16 in the extrusion process, the hydraulic oil is supplied from the unillustrated main hydraulic-oil supply source to the main cylinder 12A and the side cylinders 26. The hydraulic oil is supplied at pressure and the discharge amount necessary to advance the extrusion stem 24 and the main crosshead 22 with the desired extruding force F at the desired extrusion speed.

Note that FIG. 5 is the schematic hydraulic circuit diagram to perform the equal-pressure extrusion control method by the extrusion press device 1 according to the first embodiment. Therefore, only main valves and pressure control devices necessary for description have been denoted by the reference numerals and described. Accordingly, all of the hydraulic devices necessary for the actual hydraulic circuit are not illustrated, and valves not denoted by the reference numerals among the illustrated valves are only illustrated as “OPENED” or “CLOSED” in FIG. 5.

At the start of the extrusion, a container sealing process in which the container 18 is advanced by t container cylinders 28 and is pressed against the die 16 has been already completed. Accordingly, the divided oil chamber 56B and the divided oil chamber 66B of each of the container cylinders 28 are filled with the hydraulic oil at pressure equivalent to the initial container sealing force, and the container sealing force f is controllable by the control hydraulic circuit 84.

The hydraulic circuit according to the present embodiment in this state can perform the equal-pressure extrusion control method while variation of the extruding force F is suppressed because the hydraulic circuit includes the control hydraulic circuit 84 that includes the hydraulic-oil supply source 82 and the pressure control means 83.

The control procedure is described below with reference to FIG. 6, FIG. 7A and FIG. 7B as well. The procedure described below is divided into a procedure to calculate the complementary pressure Pa in the equal-pressure control and an equal-pressure extrusion control procedure to control operation of the container cylinders 28 by applying the calculated complementary pressure Pa.

[Calculation of Complementary Pressure Pa in Equal-Pressure Control]

As illustrated in FIG. 6, the control procedure described here includes a reference container sealing force setting step (S101 in FIG. 6), a reduced container sealing force calculation step (S103 in FIG. 6), and a complementary pressure calculation step (S105 in FIG. 6). The control procedure is a procedure to calculate the complementary pressure Pa that is applied to prevent the bursting phenomenon during the extrusion process. The procedure is executed by the controller 85.

[Reference Container Sealing Force Setting Step]

A specific exemplary procedure of the reference container sealing force setting step (S101 in FIG. 6) is described with reference to FIG. 7A as well.

First, at the start of the extrusion process, the pressure detection means 81 detects start pressure Ps of the hydraulic oil (S201).

The controller 85 acquires the start pressure Ps detected by the pressure detection means 81, and calculates start actual extruding force Fs based on the start pressure (S203). Further, the controller 85 also calculates force acting on the die 16 through the container 18 by the start actual extruding force Fs, namely, the maximum frictional force Fbmax (=maximum reaction force Fb′max) between the extrusion material EM and the container 18 by the extruding force F (S205). The controller 85 sets the maximum reaction force Fb′max as the reference container sealing force fs (S207).

[Reduced Container Sealing Force Calculation Step]

Next, the reduced container sealing force calculation step (S103 in FIG. 6) is described with reference to FIG. 7B.

The pressure detection means 81 detects in-extrusion pressure Pex that is pressure of the hydraulic oil while the extrusion process progresses, and the controller 85 acquires the detected in-extrusion pressure Pex (S301). The controller 85 calculates in-extrusion actual extruding force Fex based on the acquired in-extrusion pressure Pex, and the frictional force Fb (=reaction force Fb′) during the extrusion by the in-extrusion actual extruding force Fex (S303 and S305).

Further, the controller 85 sets the calculated reaction force Fb′ as in-extrusion container sealing force fex (S307), and calculates reduced container sealing force fd that is a difference between the in-extrusion container sealing force fex and the reference container sealing force fs (S309).

Referring back to FIG. 4C, the reduced container sealing force fd is described.

The reaction force Fb′ at the time when the extrusion material length L is L1 is regarded as the in-extrusion container sealing force fex (fex=Fb′). The controller 85 calculates the reduced container sealing force fd that is a difference between the in-extrusion container sealing force fex and the reference container sealing force fs (fd=fs−fex). The reduced container sealing force fd is substantially equal to the reduction amount of the frictional force Fb or the reduction amount of the reaction force Fb′ (Fbmax−Fb or Fb′max−Fb′) reduced during the extrusion process, and is increased along with progression of the extrusion.

[Complementary Pressure Calculation Step]

Next, the controller 85 calculates force that is substantially equal to the reduced container sealing force fd calculated in the reduced container sealing force calculation step in the extrusion direction, as the complementary pressure Pa of the container sealing force (S105 in FIG. 6). The complementary pressure Pa is supply pressure of the hydraulic oil to the container cylinders 28, and is applied to the container 18 in the extrusion direction through the container cylinders 28.

Ideally, the complementary pressure Pa preferably has the absolute value same as the absolute value of the reduced container sealing force fd. Accordingly, as illustrated in FIG. 4C, the container sealing force f to which the complementary pressure Pa is applied is coincident with the reference container sealing force fs even at timing when the extrusion material EM has any extrusion material length L, during the period from the start to the completion of the extrusion. In other words, the extrusion press device 1 to which the complementary pressure Pa is applied can maintain the reference container sealing force fs applied to the container 18 in the extrusion direction at the start of the extrusion, during the period from the start to the completion of the extrusion. In the extrusion press method by the extrusion press device 1, extrusion press at equal pressure is realized during the extrusion process in the above-described manner. Note that the container sealing force f is coincident with the reference container sealing force fs as described above; however, this occurs in an ideal situation, and the container sealing force f and the reference container sealing force fs are not coincident with each other in a realistic apparatus.

[Equal-Pressure Extrusion Control Procedure]

The controller 85 continuously calculates the complementary pressure Pa during the period from the start to the completion of the extrusion. The controller 85 controls the pressure control means 83 such that, in the control hydraulic circuit 84, the hydraulic oil is supplied from the hydraulic-oil supply source 82 to each of the oil chambers (divided oil chamber 56B and divided oil chamber 66B) of each of the container cylinders 28 at the complementary pressure Pa calculated in real time.

Although the hydraulic-oil supply source 82 may be a variable discharge hydraulic pump, the hydraulic-oil supply source 82 is preferably a hydraulic pump that controls the discharge amount based on the rotational speed of the driving motor. Further, as the pressure control means 83, a pressure control device that can control the hydraulic oil pressure of the hydraulic circuit in real time, for example, a proportional solenoid relief valve is preferably adopted.

The extrusion press device 1 according to the first embodiment performs the above-described equal-pressure extrusion control method, which makes it possible to maintain the container sealing force f at the reference container sealing force fs (=Fb′max) during the period from the start to the completion of the extrusion process as illustrated in FIG. 4C. Note that, in FIG. 4C, the start of the extrusion process is specified by Lmax, and the completion of the extrusion process is specified by Lmin. During the period, the reaction force Fb′ (in-extrusion container sealing force fex) is also reduced due to reduction of the extruding force F. However, the hydraulic oil of the complementary pressure Pa matching the reduction of the reaction force Fb′, namely, increase of the reduced container sealing force fb is supplied to the container cylinders 28. Therefore, it is possible to perform correction to compensate the reduction of the reaction force Fb′. The correction is illustrated in a correction region A hatched in FIG. 4C. As a result of the correction, the extrusion press device 1 can maintain the container sealing force f substantially constant (at reference container sealing force fs (=Fb′max)) during the extrusion process.

Further, in the above-described equal-pressure extrusion control method, the correction region A of FIG. 4C is increased and corrected by pressing the container 18 against the die 16 from the main cylinder housing 12 side by the container cylinders 28 disposed in the main cylinder housing 12. As described above, the increasing amount of the reduced container sealing force fd is substantially equal to the reduction amount (Fbmax−Fb) of the frictional force Fb reduced during the extrusion process. The reaction force acting on the container cylinders 28 during the increase correction acts between the end platen 10 and the main cylinder housing 12.

In other words, the force that acts on the same direction and is substantially equal to the reduction amount of the extruding force F reduced during the extrusion process is increased and corrected by the above-described equal-pressure extrusion control method. Accordingly, the force (reaction force of extruding force F) acting between the end platen 10 and the main cylinder housing 12 during the extrusion process is also maintained at substantially constant. In other words, when the correction region A illustrated in FIG. 4C is increased and corrected, the extruding force F (Fa+Fbmax) is maintained during the period from the start to the completion of the extrusion process as illustrated by an alternate long and short dash line in FIG. 4B that illustrates variation of the extruding force F during the extrusion process. The extruding force F propagates to the end platen 10 through the die 16.

[Effects by First Embodiment]

Next, effects achieved by the extrusion press device 1 according to the first embodiment are described. The effects include an effect relating to prevention of the bursting phenomenon and an effect relating to improvement of dimension/shape accuracy of an extrusion molded product. Further, since the container cylinders 28 are adopted, the effects include an effect to generate large output while preventing a cylinder diameter from being increased.

[Effect Relating to Improvement of Dimension/Shape Accuracy]

According to the first embodiment, the complementary pressure Pa corresponding to the reduced container sealing force fd along with progression of the extrusion is controlled to be applied to the container 18 in the extrusion direction during the period from the start to the completion of the extrusion. As a result, the constant extruding force F propagating to the end platen 10 through the die 16 is maintained during the period from the start to the completion of the extrusion. Accordingly, the amount of deflection occurred on the end platen 10 and the die 16 caused by the extruding force F is maintained in the state at the start of the extrusion, until the completion of the extrusion. Note that the deflection occurred on the end platen 10 is deflection mainly caused by curved deformation, and the deflection occurred on the die 16 is deflection caused by compression in the longitudinal direction X and curved deformation.

[Effect relating to Prevention of Bursting Phenomenon]

According to the first embodiment, the complementary pressure Pa compensating the reduced container sealing force fd along with progression of the extrusion is controlled to be applied to the container 18 in the extrusion direction during the period from the start to the completion of the extrusion. According to the first embodiment, applying the complementary pressure Pa makes it possible to secure the container sealing force f sufficient to prevent the “bursting phenomenon” during the period from the start to the completion of the extrusion.

[Energy Efficiency]

Further, according to the first embodiment, since the reduced container sealing force fd is complemented by pressing in the extrusion direction, the extruding force F is not reduced. Thus, according to the first embodiment, energy efficiency is improved as compared with the energy efficiency by Patent Literature 1 in which pressing is performed in the direction opposite to the extrusion.

[Large Output is Possible While Preventing Cylinder Diameter from Increasing]

In the extrusion press device 1 according to the first embodiment, each of the container cylinders 28 includes the plurality of, more specifically, two oil chambers, the first oil chamber 51 and the second oil chamber 61 along the longitudinal direction X. Further, the first piston 54 slidable in the longitudinal direction X in the first oil chamber 51 is formed on the first rod 52 communicating with the first oil chamber 51, and the second piston 64 slidable in the longitudinal direction X in the second oil chamber 61 is formed on the second rod 62 communicating with the second oil chamber 61. As a result, the two divided oil chambers 56A and 56B divided in the longitudinal direction X by the first piston 54 are formed in the first oil chamber 51, and the two divided oil chambers 66A and 66B divided in the longitudinal direction X by the second piston 64 are formed in the second oil chamber 61. Accordingly, the container cylinders that can generate large output are disposed in the main cylinder housing to obtain large container sealing force and large container split force while preventing the cylinder diameter from being increased. As a result, in the extrusion press device 1 according to the first embodiment, the large container sealing force and the large container split force can be obtained. Further, supplying the hydraulic oil to one of the plurality of oil chambers makes it possible to drive each of the container cylinders without increasing the supply amount of the hydraulic oil.

Second Embodiment

Next, an extrusion press device 2 according to a second embodiment and a main-crosshead retreat control method by the extrusion press device 2 are described with reference to FIG. 8.

The extrusion press device 2 itself according to the second embodiment has the basic configuration same as the configuration of the extrusion press device 1 according to the first embodiment, including the configuration of each of the container cylinders 28 disposed in the main cylinder housing 12. Accordingly, the components same as or not functionally different from the components illustrated in FIG. 1 and FIG. 5 are denoted by the same reference numerals as the reference numerals in FIG. 1 and FIG. 5, and description of such components is omitted.

The extrusion press device 2 according to the second embodiment and the extrusion press device 1 according to the first embodiment are mainly different in the hydraulic circuit. More specifically, the difference is that the extrusion press device 2 includes a main-crosshead retreat hydraulic circuit 284. The main-crosshead retreat hydraulic circuit 284 can optionally select a communication state in which discharged hydraulic oil discharged from the oil chambers (first oil chambers 51 and second oil chambers 61) of the container cylinders 28 is supplied to the side cylinders 26 and a closed state in which the discharged hydraulic oil is not supplied to the side cylinders 26.

The discharged hydraulic oil is discharged when the container 18 (container holder 19) is retreated by the container cylinders 28. Further, the discharged hydraulic oil is used to retreat the main crosshead 22 by the side cylinders 26.

The extrusion press device 2 can perform the main-crosshead retreat control method. The main-crosshead retreat control method reduces a time necessary to retreat the container 18, the extrusion stem 24, and the main crosshead 22 for next extrusion process after completion of one extrusion process by utilizing characteristics of the container cylinders 28. A procedure of the retreat control is described in order below.

After the completion of the extrusion process, the container 18 and the main crosshead 22 (extrusion stem 24) are retreated to expose the extrusion material EM as a discard on an end surface of the die 16.

Next, an unillustrated shear device or the like to shear the discard is lowered, from above, between the die 16 and the container 18, and the discard exposed on the end surface of the die 16 is sheared and removed.

Next, the main crosshead 22 is retreated to a retreat limit position (main-crosshead retreating step), and preparation to store a new extrusion material EM in the container 18 is performed.

More specifically, a valve 201C is first closed to close the hydraulic circuit that supplies the hydraulic oil from a main pump 282 (normally, provided in plural) as the main hydraulic-oil supply source to the side cylinders 26. Thereafter, a valve 201E is opened to shift the main-crosshead retreat hydraulic circuit 284 from the closed state to the communication state (container retreat preparation step).

Next, a space length to supply the new extrusion material EM is secured between the container 18 and the extrusion stem 24. To secure the space length, a valve 201A is opened to supply the hydraulic oil from the main pump 282 to the divided oil chamber 56A (first oil chamber 51) and the divided oil chamber 66A (second oil chamber 61) of each of the container cylinders 28, and the container 18 is retreated to the retreat limit position (container retreating step). Note that, to increase the retreating speed of the container 18, the following procedure can be adopted. The hydraulic oil is supplied from the main pump 282 to one of the divided oil chamber 56A and the divided oil chamber 66A of each of the container cylinders 28, and the other divided oil chamber can suck the hydraulic oil from a hydraulic oil tank through release of an unillustrated tank line.

At this time, the main-crosshead retreat hydraulic circuit 284 is in the communication state. Therefore, the hydraulic oil discharged from the two oil chambers of each of the container cylinders 28 is wholly supplied to oil chambers of the side cylinders 26 on the rod side through the valve 201B. As a result, the main crosshead 22 is retreated.

Also in the existing extrusion press device, the discharged hydraulic oil discharged from the container cylinders 28 is wholly supplied to the side cylinders 26 to retreat the main crosshead 22 when the container 18 is retreated, in some cases. However, the volume of the discharged hydraulic oil discharged from the container cylinders 28 until the container 18 reaches the retreat limit position is typically lower than the volume of the supplied hydraulic oil necessary to cause the main crosshead 22 to reach the retreat limit position. In this case, after the container 18 has reached the retreat limit position, it is necessary to switch the hydraulic circuit to supply the hydraulic oil from the main hydraulic-oil supply source to the side cylinders 26 and to retreat the main crosshead 22 that has not reached the retreat limit position yet, to the retreat limit position anew. This makes it difficult to reduce the time necessary to retreat the main crosshead 22 to the retreat limit position (main-crosshead retreating step).

As described in the first embodiment, the container cylinders 28 of the extrusion press device 2 can generate large output while preventing the cylinder diameter from being increased. This makes it possible to increase the volume of the discharged hydraulic oil discharged from the container cylinders 28. As a result, the main crosshead 22 is retreated to a position closer to the retreat limit position before the container 18 reaches the retreat limit position, which makes it possible to reduce the time necessary for the main-crosshead retreating step.

Further, the container cylinders 28 can be configured so as to make the volume of the discharged hydraulic oil discharged from the container cylinders 28 themselves substantially equal to or larger than the volume of the supplied hydraulic oil necessary to cause the main crosshead 22 to reach the retreat limit position by the side cylinders 26. As a result, the main-crosshead retreating step can be completed by the above-described main-crosshead retreat control method at the substantially same time as or before completion of the container retreating step. This makes it possible to further reduce the time necessary for the main-crosshead retreating step. In addition, after the completion of the container retreating step, it is unnecessary to supply the hydraulic oil from the main hydraulic-oil supply source to the side cylinders for retreating operation of the main crosshead to the retreat limit position again. As a result, it is possible to supply the substantially whole amount of hydraulic oil from the main hydraulic-oil supply source to the shear device (discard shearing device), which reduces the time necessary to shear the discard. As described above, it is possible to reduce not only the time necessary for the main-crosshead retreating step but also the idle time itself.

Further, the container cylinders 28 of the extrusion press device 2 according to the second embodiment are disposed together with the side cylinders 26 in the main cylinder housing 12. Accordingly, the main-crosshead retreat hydraulic circuit 284 can be configured with an extremely short hydraulic pipe length. This makes it possible to reduce assembly man-hours for the hydraulic pipes and the like of the extrusion press device and to reduce the amount of hydraulic oil staying inside the hydraulic pipes. Note that, since FIG. 8 is a schematic hydraulic circuit diagram to perform the main-crosshead retreat control method by the extrusion press device according to the second embodiment, only the main valves necessary for description have been denoted by the reference numerals and described. Accordingly, all of the hydraulic devices necessary for the actual hydraulic circuit are not illustrated, and valves not denoted by the reference numerals among the illustrated valves are only illustrated as “opened” or “closed” in FIG. 8. Note that, in the schematic hydraulic circuit diagram of FIG. 8, a symbol of a variable discharge hydraulic pump is illustrated as the main pump 282; however, the main pump 282 may be a hydraulic pump, the discharge amount of which is controlled through rotational speed control of a driving motor.

Although the first embodiment and the second embodiment have been described above as the preferred embodiments of the present invention, the present invention is not limited to the above-described embodiments, and can be implemented in various forms without departing from the scope described in the appended claims.

For example, in the first embodiment, the reference container sealing force fs and the in-extrusion container sealing force fex are detected during the extrusion process, and control to calculate the reduced container sealing force fb, and the like are performed based on the detection result; however, the present invention not limited thereto. The present invention includes, for example, the following forms.

In a case where extrusion press is repeatedly performed on the same extrusion material by the extrusion unit having the same specification under the same extrusion condition, control is performed based on the reference container sealing force fs and the like detected during the extrusion process in the first extrusion press, in a manner similar to the first embodiment. In a subsequent extrusion press, however, extrusion press with equal-pressure control can be performed by using the reference container sealing force fs and the like detected in the first extrusion press. More specifically, function data or table data illustrated in the graph of FIG. 4C is generated in the first extrusion press, and the equal-pressure control can be performed based on the generated data in the subsequent extrusion press.

Further, in the first embodiment, the tandem cylinder form in which each of the container cylinders 28 includes the two oil chambers (first oil chamber 51 and second oil chamber 61) has been mainly described. Alternatively, as long as restriction of the arrangement of the container cylinders in the main cylinder housing can be satisfied, a form including three or more oil chambers or a single cylinder form in which one oil chamber illustrated in FIG. 5 is divided by one piston may be adopted.

Further, in the first embodiment, the control hydraulic circuit 84 has been described on the premise of execution of the equal-pressure extrusion control method. In the present invention, however, the hydraulic oil supplied from the hydraulic-oil supply source 82 to the container cylinders 28 may be selectively supplied to the divided oil chambers 56B and 66B or the divided oil chambers 56A and 66A of the container cylinders 28 by a direction selector valve or the like. To advance the container 18, the former is selected. To retreat the container 18, the divided oil chambers 56A and 66A are selected.

In the above-described case, as with the case in which the retreating speed of the container 18 is increased, the hydraulic oil is supplied from the main pump 282 to only one of the divided oil chamber 56B (first oil chamber 51) and the divided oil chamber 66B (second oil chamber 61) of each of the container cylinders 28. In contrast, the other divided oil chamber may suck the hydraulic oil from a hydraulic oil tank through release of an unillustrated tank line.

In the first embodiment, it has been described that the hydraulic-oil supply source 82 can be driven together with the main hydraulic-oil supply source at a time other than the extrusion process. Further, the hydraulic-oil supply source 82 may be driven together with the main hydraulic-oil supply source not only in the case where the container 18 is advanced but also in the case where the container 18 is retreated, by a method other than the equal-pressure extrusion control method.

For example, there are a case where the discard at the completion of extrusion is long, a case where the extrusion material length L of the extrusion material EM inside the container 18 in the middle of the extrusion process is long due to extremely-small lot production, and a case where a high strength material is used. In these cases, the container strip force that is force necessary to retreat the container 18 is increased as compared with the normal container strip force. When the large container strip force is necessary in such cases and a case other than the cases, the hydraulic oil of pressure higher than the normal pressure may be supplied to the container cylinders 28 by the pressure control means 83 to retreat the container 18. The configuration of each of the container cylinders 28 described in the first embodiment can generate the high container strip force.

The equal-pressure extrusion control method has been described in the first embodiment, and the main-crosshead retreat control method has been described in the second embodiment. To perform these control methods, the configurations described in the respective embodiments may be combined and included. In this case, both of the control method in the first embodiment and the control method in the second embodiment are performable. For example, the valve 201B of the main-crosshead retreat hydraulic circuit 284 in the main-crosshead retreat control method described in the second embodiment, is closed. When the main-crosshead retreat hydraulic circuit 284 is in the closed state in the above-described manner, the equal-pressure extrusion control method described in the first embodiment is performable by the control hydraulic circuit 84.

Furthermore, although the container cylinders 28 are disposed in the main cylinder housing 12 in the first embodiment and the second embodiment, the container cylinders 28 may be disposed in an optional object as long as the container cylinders 28 can exert the function.

REFERENCE SIGNS LIST

• 1, 2 Extrusion press device
• 3 Extrusion unit
• 5 Control unit
• 10 End platen
• 12 Main cylinder housing
• 12A Main cylinder
• 12B Main ram
• 14 Tie rod
• 16 Die
• 18 Container
• 19 Container holder
• 22 Main crosshead
• 24 Extrusion stem
• 26 Side cylinder
• 28 Container cylinder
• 28A Cylinder rod
• 51 First oil chamber
• 52 First rod
• 53 First cylinder body
• 54 First piston
• 55 Seal fixing member
• 56A, 56B, 66A, 66B Divided oil chamber
• 61 Second oil chamber
• 62 Second rod
• 63 Second cylinder body
• 64 Second piston
• 65 Closing member
• 71 Coupling portion
• 81 Pressure detection means
• 82 Equal-pressure extrusion control hydraulic-oil supply source
• 83 Equal-pressure extrusion control pressure control means
• 84 Equal-pressure extrusion control hydraulic circuit
• 85 Controller
• 201 valve
• 201B Valve
• 201C Valve
• 282 Main pump
• 284 Main-crosshead retreat hydraulic circuit
• A Correction region
• EM Extrusion material
• P1 Hydraulic pipe
• P2 Hydraulic pipe
• P3 Hydraulic pipe
• P4 Hydraulic pipe

Claims

1. An extrusion press device, comprising:

an extruder comprising a container configured to store an extrusion material, and an end platen configured to support a die from which the extrusion material is extruded; and

a controller configured to control operation of the extruder by controlling a container sealing force that presses the container against the die,

wherein the controller is configured to control application of a complementary pressure corresponding to a reduced container sealing force to the container in a direction of the extrusion during a period from a start to completion of the extrusion, the reduced container sealing force being increased during progression of extrusion.

2. The extrusion press device according to claim 1, wherein the controller is further configured to controls application of the complementary pressure such that a reference container sealing force is maintained during the period from the start to the completion of the extrusion, the reference container sealing force being the container sealing force at the start of the extrusion.

3. The extrusion press device according to claim 2, wherein the controller is further configured to determine the container sealing force at the start of the extrusion as the reference container sealing force.

4. The extrusion press device according to claim 3, wherein the controller is further configured to determine the reduced container sealing force as a difference between the container sealing force during the extrusion and the reference container sealing force.

5. The extrusion press device according to claim 1, wherein the controller is further configured to control application of the complementary pressure as a force of 20% or more and 30% or less of a maximum actual extruding force at the start of the extrusion, to the container.

6. The extrusion press device according to claim 1, wherein:

the extruder comprises a container cylinder configured to advance the container toward the end platen or withdraw the container from the end platen,

the container cylinder comprises a first oil chamber and a second oil chamber that are arranged in a longitudinal direction along the extrusion direction, and

each of the first oil chamber and the second oil chamber comprises two divided oil chambers divided in the longitudinal direction.

7. The extrusion press device according to claim 6, further comprising:

an equal-pressure extrusion control hydraulic circuit configured to supply hydraulic oil to one or both of the first oil chamber and the second oil chamber of the container cylinder when the container is advanced by the container cylinder, and

the equal-pressure extrusion control hydraulic circuit is independent of a hydraulic circuit configured to extrude the extrusion material.

8. An extrusion press method of extruding an extrusion material from a die while pressing a container against the die with a container sealing force, the extrusion material being extruded from the die and being stored in the container, the extrusion press method comprising;

applying a complementary pressure corresponding to a reduced container sealing force to the container in a direction of the extrusion during a period from the start to completion of the extrusion, wherein:

the container sealing force at a start of extrusion is a reference container sealing force,

the container sealing force during the extrusion is an in-extrusion container sealing force, and

a difference between the reference container sealing force and the in-extrusion container sealing force is the reduced container sealing force.

9. The extrusion press method according to claim 8, wherein the complementary pressure is applied such that the reference container sealing force is maintained during the period from the start to the completion of the extrusion.

10. The extrusion press method according to claim 8, wherein:

the reference container sealing force and the in-extrusion container sealing force are based on information detected at and after the start of the extrusion, and

the reduced container sealing force and the complementary pressure are determined during the extrusion, based on the detected reference container sealing force and the detected in-extrusion container sealing force.