EXTRUSION PRESS MACHINE AND PLATEN FOR EXTRUSION PRESS MACHINE

Abstract

An extrusion press machine includes: a die configured to extrusion-mold a workpiece; a cylinder configured to apply pressing force to press the workpiece against the die; and a platen configured to receive the pressing force from the die. The platen includes an outside element and an inside element that is disposed coaxially with the outside element, inside the outside element. The inside element includes one or more fluid supply structures each supplying a cooling medium toward an extruded product extruded from the die.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a continuation of PCT Patent Application No. PCT/JP2019/038082 filed Sep. 27, 2019. The content of this application is incorporated by reference herein in its entirety.

TECHNICAL FIELD

The present invention relates to an extrusion press machine used for extrusion molding of a metal such as an aluminum alloy, and in particular, to a platen.

BACKGROUND ART

To extrusion-mold a metal material by an extrusion press machine, a billet is pressed with extruding force against a die disposed on a platen through a pressure ring. The extruding force is applied by a main cylinder included in the extrusion press machine. When reaction force of the extruding force acts on the platen and a main cylinder housing during an extrusion process, deflection occurs on the platen. With the deflection of the platen, deflection occurs on the pressure ring and the die. The platen may also be referred to as an end platen.

FIG. 9 illustrates deflection occurring on a platen 220.

As illustrated in an upper diagram of FIG. 9, reaction force f of extruding force F acts on a substantially center part of the platen 220 in an extrusion direction through a die 260 and a pressure ring 250. The extrusion direction is the direction same as a direction of a void arrow indicating the extruding force F. In contrast, against the reaction force f, drag f′ in a direction opposite to the direction of the reaction force f is generated in tie rods 287. The tie rods 287 resist the reaction force f by deforming (extending) in a direction parallel to the extrusion direction within an elastic range. As a result, a bending moment M bending the platen 220 to protrude the substantially center part of the platen 220 in the extrusion direction is generated in the platen 220. However, in the platen 220 including a discharge path 242 that penetrates through the platen 220 in a thickness direction to continuously extrusion-mold (discharge) a product rearward, it is physically difficult to secure sufficient rigidity against the bending moment M near the discharge path 242. Therefore, during the extrusion process, deflection and bending deformation occur as illustrated in a lower diagram of FIG. 9.

Although FIG. 9 is a schematic plan view, deflection of the platen 220 occurs in a view from a side surface as in the plan view because the tie rods 287 are disposed at four corners of the platen 220. In other words, in a three-dimensional view, deflection occurs such that the substantially center part of the platen 220 protrudes in the extrusion direction.

Further, when the platen 220 is deflected by the extruding force F during the extrusion process, the pressure ring 250 and the die 260 fixed to the platen 220 also deform with the deflection of the platen 220.

The extruding force acting on the platen during the extrusion process is varied, more specifically, is reduced as illustrated in FIG. 10 during a period from start to completion of the extrusion. Therefore, the deflection of the platen 220 is reduced during the extrusion process. With reduction of the deflection, the deformation of the pressure ring and the die may be also reduced. Therefore, a dimension of a product extrusion-molded by the die is varied during the period from start to completion of the extrusion process, and it is difficult to obtain desired dimensional accuracy of the product depending on a degree of deformation variation of the die. A lateral axis of a graph in FIG. 10 indicates a length L of the billet during the extrusion process, and a vertical axis indicates the extruding force F necessary for extrusion molding of the billet. The extruding force F is expressed by a sum of necessary extruding force Fa acting on the die through the billet and frictional force fb between an outer peripheral surface of the billet and an inner peripheral surface of a container housing the billet, namely, F=Fa+fb. The above-described reduction of the extruding force during the extrusion process is caused by reduction of the frictional force fb. Further, the necessary extruding force Fa is constant and is not varied during the extrusion process by ignoring thermal influence.

Patent Literature 1 discloses a pressure ring with which deflection during an extrusion process can be suppressed, and an extrusion press machine using the pressure ring. The pressure ring disclosed in Patent Literature 1 has a double structure including an outside member and an inside member, and the outside member is shrink-fitted to the inside member. According to the pressure ring disclosed in Patent Literature 1, since the outside member is shrink-fitted to the inside member, stress from outside to inside in a radial direction is applied to the inside member. Therefore, even when a load is applied in an axial direction of the pressure ring, the stress from outside to inside resists the load, which suppresses deflection.

CITATION LIST

Patent Literature

Patent Literature 1: JP H10-258309 A

SUMMARY OF INVENTION

Technical Problem

According to Patent Literature 1, it is possible to suppress deflection of the pressure ring. However, the deflection of the pressure ring is based on the deflection of the platen. Even when the stress from outside to inside is generated in the pressure ring having the double structure, the deflection of the platen cannot be eliminated. Therefore, it is difficult to suppress deformation variation of the pressure ring and the die during the extrusion process, to a degree sufficient to obtain high dimensional accuracy of the product.

Therefore, an object of the present invention is to provide an extrusion press machine including a platen in which occurrence of deflection can be suppressed.

Solution to Problem

An extrusion press machine according to the present invention includes: a die configured to extrusion-mold a workpiece; a cylinder configured to apply pressing force to press the workpiece against the die; and a platen configured to receive the pressing force from the die.

The platen according to the present invention includes an outside element and an inside element that is disposed coaxially with the outside element, inside the outside element.

The inside element according to the present invention includes one or more fluid supply structures each supplying a cooling medium toward an extruded product extruded from the die.

The inside element according to the present invention is preferably provided to sandwich the outside element from front and rear surfaces of the outside element.

In the platen according to the present invention, the outside element and the inside element are preferably fitted, tensile stress is preferably generated in an axial direction (C) in the inside element, and compression stress corresponding to the tensile stress is preferably generated in the outside element.

The inside element according to the present invention is preferably provided to sandwich the outside element by fastening.

In the platen according to the present invention, the outside element and the inside element fitted to each other preferably have a gap in a portion not concerning fitting.

The inside element according to the present invention preferably includes a large-diameter portion provided on a front side, a small-diameter portion continuous with the large-diameter portion, and a fastening member fastened with the small-diameter portion.

The fastening member is fastened in advance with the small-diameter portion to press the outside element, and a preliminary load greater than or equal to a load acting during the extrusion process is accordingly applied. As a result, tensile stress is generated in the inside element.

In the outside element according to the present invention, compression stress is preferably generated in an area sandwiched by the inside element.

The outside element according to the present invention preferably includes a first outside element adjacently fitted to outside of the inside element, and a second outside element adjacently fitted to outside of the first outside element. The inside element is provided to sandwich the first outside element from front and rear surfaces of the first outside element.

Tensile stress is preferably generated in an axial direction (C) in the inside element, and compression stress corresponding to the tensile stress is preferably generated in the first outside element.

In the outside element according to the present invention, the first outside element and the second outside element are preferably fitted by shrinkage fit.

The inside element according to the present invention preferably includes a plurality of the aforementioned fluid supply structures (160)

The inside element according to the present invention is preferably made of a metal material that has a longitudinal elastic modulus substantially same as or greater than a longitudinal elastic modulus of the outside element.

Advantageous Effects of Invention

According to the present invention, the inside element sandwiches the outside element from the front and rear surfaces of the outside element. The sandwiching generates the tensile stress in the inside element and generates the compression stress in the outside element. Therefore, even when a load acts in the extrusion direction during the extrusion process, the tensile stress generated in the inside element and the compression stress generated in the outside element are maintained while being reduced. Thus, even if deflection occurs on the outside element, a portion where the tensile stress or the compression stress is generated is hardly deflected.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a partial cross-sectional plan view illustrating a schematic configuration of an extrusion press machine including a platen according to a first embodiment.

FIG. 2 is a partial cross-sectional plan view illustrating a configuration of the platen in FIG. 1 and an enlarged view of a part thereof.

FIG. 3 is an axially-exploded view illustrating the platen in FIG. 2.

FIG. 4 is a diagram illustrating another form of the platen in FIG. 2.

FIG. 5 is a front view illustrating a platen according to a second embodiment.

FIG. 6 is a partial cross-sectional plan view illustrating a configuration of the platen in FIG. 5.

FIG. 7 is an axially-exploded view illustrating the platen in FIG. 6.

FIG. 8 is a cross-sectional view illustrating a configuration of a fluid supply structure 160 provided in the platen in FIG. 6.

FIG. 9 is a diagram to explain deflection occurring in a platen.

FIG. 10 is a graph illustrating variation of extruding force F during an extrusion process.

DESCRIPTION OF EMBODIMENTS

An extrusion press machine according to the present invention is described below based on embodiments. The extrusion press machine according to the embodiments includes a platen including a plurality of elements divided in a radial direction. Among the plurality of divided elements, an element disposed on an inside (i.e., inside element) is fixed with a pressure ring. The inside element penetrates an element(s) disposed outside the inside element and sandwich the element(s) disposed on the outside from front and rear surfaces. Since the platen according to the embodiments has such a structure, deflection during the extrusion process can be suppressed.

The embodiments include a first embodiment in which the platen has a structure divided into two elements in the radial direction, and a second embodiment in which the platen has a structure divided into three elements in the radial direction. The first embodiment and the second embodiment are described below in order.

First Embodiment

Based on an extrusion press machine 1 according to the first embodiment, a platen 20 according to the present embodiment is described.

As illustrated in FIG. 1, the extrusion press machine 1 includes an extrusion unit 10 from which a billet B as a workpiece is extruded, a holding unit 70 housing and holding the billet B, and a pressure generation unit 80 generating a load to press the billet B housed in the holding unit 70, toward the extrusion unit 10. The platen 20 is a main element configuring the extrusion unit 10.

Extrusion Unit 10

As illustrated in FIG. 1, FIG. 2, and FIG. 3, the extrusion unit 10 includes the platen 20, a pressure ring 50 supported by the platen 20, and a die 60 supported by the pressure ring 50.

The platen 20 includes an outside element 30 and an inside element 40 that is coaxially supported inside the outside element 30 by fitting, and has a two-layer structure divided in the radial direction.

Outside Element 30

As illustrated in FIG. 2 and FIG. 3, the outside element 30 is a rectangular parallelepiped member including a thick portion 31 provided on a rear side and a thin portion 33 continuous with the thick portion 31 and is provided on a front side. A “thickness” of each of the thick portion 31 and the thin portion 33 indicates a distance from an inner peripheral surface of a holding hole 35 described below to an outer peripheral surface of the outside element 30. The outside element 30 includes the holding hole 35 that is provided inside the thick portion 31 and the thin portion 33 and penetrates through the outside element 30 in a front-rear direction. The inside element 40 is fitted to the holding hole 35. The holding hole 35 includes a small-inner-diameter portion 36 corresponding to the thick portion 31, and a large-inner-diameter portion 37 corresponding to the thin portion 33, and is formed in a step shape in the front-rear direction. The outside element 30 is normally made of cast iron. The inside element 40 is similarly fabricated.

In the extrusion press machine 1, a side (F) illustrated in FIG. 1 is defined as a front side, and a side (B) is defined as a rear side. Further, a dimension in the radial direction is determined based on a center axis C illustrated in FIG. 1 and FIG. 2.

Inside Element 40

As illustrated in FIG. 2 and FIG. 3, the inside element 40 is a cylindrical member including a large- diameter portion 41 provided with an attachment surface 48 for the pressure ring 50, and a small-diameter portion 43 continuous with the large-diameter portion 41 and is provided so as to penetrate through the thick portion 31 in the front-rear direction. The inside element 40 has an appearance similar to a bolt. The large-diameter portion 41 corresponds to a head portion, and the small-diameter portion 43 corresponds to a shank portion.

An outer diameter of the inside element 40 is smaller than a length of each of outer surfaces (top and bottom surfaces and both side surfaces) of the outside element 30, and is considered to substitute a part on the inner diameter side of the outside element 30. When a preliminary load is acted, surface pressure ΔP described below corresponding to the preliminary load is generated on a pressure receiving surface 32 of the outside element 30 (thick portion 31) in FIG. 2. The diameter of each of the large-diameter portion 41 and the small-diameter portion 43 of the inside element 40 determining an area of the ring-shaped pressure receiving surface 32 is determined in consideration of a diameter of the used die 60 and a diameter of the pressure ring 50, such that the surface pressure ΔP becomes lower than a yield point of the material strength of the outside element 30 in anticipation of safety factor.

ΔP=A/F

A=π·(D²−d²)/4

ΔP: surface pressure of pressure receiving surface 32

F: extruding force (preliminary load MF)

A: area of pressure receiving surface 32

φD: outer diameter of large-diameter portion 41

φd: outer diameter of small-diameter portion 43

The inside element 40 includes a discharge path 42 that penetrates through the inside element 40 from the large-diameter portion 41 to the small-diameter portion 43 in the front-rear direction. An extruded product extruded through the die 60 passes through the discharge path 42 and is discharged rearward from the extrusion press machine 1. The inside element 40 further includes a male thread 44 on an outer peripheral end on the rear side of the small-diameter portion 43. The male thread 44 of the small-diameter portion 43 is fastened with a female thread 47 of a fastening member 46 described below. The inside element 40 further includes a pressure receiving surface 45 connecting the large-diameter portion 41 and the small-diameter portion 43. The pressure receiving surface 45 is a surface receiving pressure from the outside element 30 in a direction parallel to the center axis C, namely, in an axial direction. As the pressure receiving surface 45 and the pressure receiving surface 32 of the outside element 30, planes orthogonal to the center axis C are illustrated; however, the pressure receiving surface 45 and the pressure receiving surface 32 may have the other shapes as long as the pressure receiving surface 45 and the pressure receiving surface 32 can receive pressure from each other. For example, tapered surfaces inclined in an extrusion direction Ed (FIG. 1) or step-shaped surfaces can be adopted.

The inside element 40 includes the fastening member 46 to fix the large-diameter portion 41 and the small-diameter portion 43 to the outside element 30. The fastening member 46 has a form similar to a nut, and includes, on the inner peripheral surface, the female thread 47 to be fastened with the male thread 44 provided in the small-diameter portion 43. The first embodiment is characterized in that, in a state where the preliminary load MF is generated during assembly of the extrusion press machine 1, tensile stress PF in the direction parallel to the center axis C is constantly generated in the inside element 40 by fastening the fastening member 46 in advance with the small-diameter portion 43 from the rear side of the platen 20.

The preliminary load MF is set to a value greater than or equal to a rated load acting on the inside element 40 through the pressure ring 50 and the die 60 during the extrusion process. An example of a procedure to generate the preliminary load MF is described below.

In the first embodiment, at least the male thread 44 of the small-diameter portion 43 protrudes rearward from the outside element 30, and the female thread 47 of the fastening member 46 is fastened with the male thread 44. As a result, the thick portion 31 of the outside element 30 is sandwiched by the inside element 40 and the fastening member 46 that are fastened with each other.

The fastening member 46 is required to be screwable to the male thread 44 of the inside element 40 from the rear side of the platen 20 and to include the discharge path 42 to discharge the product extruded from the die 60, from the platen 20. As long as the fastening member 46 satisfies the requirements, a female thread 44′ processed on the inner peripheral surface of the small-diameter portion 43 of the inside element 40 and a male thread 47′ processed on the outer peripheral surface of a portion protruding from a fastening member 46′ to the inner peripheral surface of the small-diameter portion 43 may be fastened as illustrated in FIG. 4.

Pressure Ring 50

As illustrated in FIG. 1 to FIG. 3, the pressure ring 50 is attached to the attachment surface 48 of the inside element 40 with unillustrated bolts or the like, and receives pressing force from the die 60 and transmits the pressing force to the inside element 40. The pressure ring 50 includes a passage 51 communicating with the discharge path 42 of the inside element 40. The pressure ring 50 is made of a material higher in strength than the outside element 30 and the inside element 40, for example, tool steal.

Holding Unit 70

As illustrated in FIG. 1, the holding unit 70 includes a container 71 holding the billet B, a container holder 73 holding the container 71, and a container cylinder 75 pressing the container 71 against the die 60 through the container holder 73.

The container 71 includes a holding chamber 72 penetrating through the container 71 in the front-rear direction while being supported by the container holder 73. The billet B is held by the container 71 while being housed in the holding chamber 72.

The container holder 73 holds the container 71. The container 71 held by the container holder 73 can reciprocate in the front-rear direction, integrally with the container holder 73.

The container cylinder 75 includes a cylinder 76 fixed to the platen 20, and a piston rod 77 provided so as to advance and retreat to/from the cylinder 76. The piston rod 77 has a front end portion fixed to the container holder 73. When the container cylinder 75 is operated, the container 71 can be pressed against the die 60 through the container holder 73.

Pressure Generation Unit 80

As illustrated in FIG. 1, the pressure generation unit 80 includes a main cylinder housing 81 disposed to face the platen 20, and a main cylinder 83 supported at substantially center of the main cylinder housing 81. The pressure generation unit 80 further includes a side cylinder 85 supported by the main cylinder housing 81 on a periphery of the main cylinder 83, and tie rods 87 supported by the main cylinder housing 81 on a periphery of the main cylinder 83.

The main cylinder 83 includes a main ram 84, a main crosshead 86 fixed to a front end of the main ram 84, and an extrusion stem 88 attached to the main crosshead 86. When the main cylinder 83 operates the main ram 84 toward the platen 20, the extrusion stem 88 presses the billet B against the die 60.

The tie rods 87 and tie rod nuts 89 couple the main cylinder housing 81 and the platen 20. The tie rods 87 and the tie rod nuts 89 couple four corners of the platen 20 and corresponding four corners of the main cylinder housing 81. During the extrusion process, reaction force of the extruding force acts on the platen 20 through the die 60 and the pressure ring 50 and acts on the main cylinder housing 81 through the main cylinder 83 in a direction in which the platen 20 and the main cylinder housing 81 are separated from each other. The tie rod nuts 89 configuring large-diameter portions of the respective tie rods 87 restrain movement of the platen 20 and the main cylinder housing 81 against the reaction force. Each of the tie rods 87 is configured to have strength resisting against the reaction force of the extruding force while allowing extension of the tie rod 87 in the elastic region.

Operation of Extrusion Press Machine 1

Operation of the extrusion press machine 1 including the above-described configuration is described.

To extrusion-mold the billet B as the workpiece by the extrusion press machine 1, the container cylinder 75 presses the container 71 against the die 60 disposed on the platen 20 through the pressure ring 50 by unillustrated holding means. Further, the extrusion stem 88 is moved toward the platen 20 to press the billet B housed in the container 71, against the die 60. This process is called an upset process. The main ram 84 is further moved toward the platen 20 to cause the extrusion stem 88 to press the billet B against the die 60, thereby continuously extrusion-molding a predetermined product rearward from a die hole 61 of the die 60. The process is called the extrusion process. Note that a cylinder rod of the side cylinder 85 is also fixed to the main crosshead 86, and the side cylinder 85 is driven during the extrusion process, namely, when the main crosshead 86 is advanced and retreated.

Procedure to Generate Tensile Stress PF

Next, an example of a procedure to generate the tensile stress PF in advance in a direction parallel to the center axis C in the inside element 40 by the preliminary load MF is briefly described with reference to FIG. 1 to FIG. 3.

Temporary Fixing of Outside Element 30 and Inside Element 40

First, the pressure ring 50 is fixed to the attachment surface 48 of the inside element 40 of the platen 20 with unillustrated bolts or the like. At this point, the fastening member 46 is detached.

Subsequently, the inside element 40 to which the pressure ring 50 has been fixed is inserted into the holding hole 35 of the outside element 30 of the platen 20 by a crane, a dedicated insertion tool, or the like. The outer diameter of the small-diameter portion 43 of the inside element 40 and the inner diameter of the small-inner-diameter portion 36 of the holding hole 35 have a clearance satisfying positioning criteria of the inside element 40 to the outside element 30. Therefore, it is not particularly necessary to position the inside element 40 to the outside element 30. On the other hand, an opening diameter of a housing chamber 39 in which the large-diameter portion 41 is to be housed is greater than the outer diameter of the large-diameter portion 41 of the inside element 40 (FIG. 2), and a predetermined clearance S is secured. The opening diameter of the housing chamber 39 indicates the inner diameter of the large-inner-diameter portion 37 of the holding hole 35. The clearance S is described below. In this state, a part of the male thread 44 of the small-diameter portion 43 of the inside element 40 is exposed rearward from the outside element 30. The female thread 47 of the fastening member 46 is screwed to the male thread 44 by using a crane, a dedicated insertion tool, or the like, thereby temporarily fastening the fastening member 46 with the small-diameter portion 43.

Action of Preliminary Load MF

Next, the preliminary load MF greater than or equal to a load (rated load) acting in the extrusion direction Ed during the extrusion process, is applied between the platen 20 and the main cylinder housing 81. More specifically, in place of the die 60, for example, a dummy die that has a product shape but has no opening is disposed on the pressure ring 50 by unillustrated holding means, and the container cylinder 75 presses the container 71 in which no billet B is housed, against the dummy die.

Thereafter, the main cylinder 83 and the side cylinder 85 are driven, the extrusion stem 88 including an unillustrated extrusion tool or the like attached to the front end thereof is moved toward the platen 20 inside the holding chamber 72 of the container 71, thereby directly applying the extruding force to the dummy die by the extrusion tool. At this time, hydraulic oil pressure supplied to the main cylinder 83 and the side cylinder 85 is controlled such that the extruding force (preliminary load MF) applied between the platen 20 and the main cylinder housing 81 through the dummy die is greater than or equal to the load (rated load) acting in the extrusion direction Ed during the extrusion process. The preliminary load MF is preferably set to 105% to 110% of the rated load.

When the preliminary load MF greater than the rated load is applied, the platen 20 is largely compressed through the pressure receiving surface 45 of the inside element 40, as compared with during the extrusion process with the rated load.

Retightening of Fastening Member 46

Further, in this state, the fastening member 46 temporarily fastened is screwed to the male thread 44 of the small-diameter portion 43 of the inside element 40 from the rear side of the platen 20 by a dedicated screwing tool or the like, so as to be retightened. Since the preliminary load MF is applied to the inside element 40 in the extrusion direction Ed, rotation stopper means to restrain relative rotary motion of the inside element 40 to the outside element 30 is unnecessary. Further, the outside element 30 included in a projection area of the pressure receiving surface 45 in the extrusion direction Ed is further compressed as compared with during the extrusion process with the rated load. Therefore, the tensile stress PF corresponding to the preliminary load MF can be constantly generated in the direction parallel to the center axis C of the inside element 40 without applying large screwing force, when the preliminary load MF is released after the fastening member 46 is screwed to the small-diameter portion 43 of the inside element 40.

Effects by First Embodiment

Next, effects by the platen 20 according to the first embodiment are described. The effects include a first effect by generation of the above-described stress state between the outside element 30 and the inside element 40, and a second effect by provision of the clearance S. The effects are described in order below.

First Effect by Stress State between Outside Element 30 and Inside Element 40

In the first embodiment, the inside element 40 sandwiches the outside element 30 from the front and rear surfaces of the outside element 30. As a result, the tensile stress PF is generated in the inside element 40 in the direction parallel to the center axis C, and compression stress CF is generated on a portion of the outside element 30 sandwiched between the pressure receiving surface 45 of the inside element 40 and the fastening member 46. The tensile stress PF and the compression stress CF are each corresponding to the preliminary load MF greater than the rated load. Therefore, even when the load acting in the extrusion direction Ed during the extrusion process is the maximum, namely, is substantially equal to the rated load, the tensile stress PF generated in the inside element 40 and the compression stress CF generated in the outside element 30 are maintained while being reduced. Therefore, even when the tie rods 87 are extended and deflection occurs on the outside element 30 of the platen 20, the fastening state of the inside element 40 and the fastening member 46 at the substantially center part of the platen 20 is maintained, and deflection hardly occurs.

As described above, according to the present embodiment, the fastening state of the inside element 40 and the fastening member 46 at the substantially center part of the platen 20 and the compression stress CF in the fastening state are maintained during the extrusion process. Therefore, even when the discharge path 42 through which the product is extruded and discharged to the rear side of the platen 20 is provided in the inside element 40, rigidity sufficient to resist a bending moment M (FIG. 9) that causes deflection on the platen 20, in particular, on the outside element 30, can be secured at the portion of the thick portion 31 of the outside element 30 held by the inside element 40 (large-diameter portion 41) and the fastening member 46, near the discharge path 42. Thus, according to the first embodiment, it is possible to exert the first effect to suppress deflection of the platen 20.

Second Effect by Provision of Clearance S

In the first embodiment, providing the clearance S makes it possible to suppress, even when deflection occurs on the platen 20, influence of the deflection on the pressure ring 50. The effect is described below with reference to a partial enlarged view of FIG. 2.

In the partial enlarged view, a state before deflection occurs on the outside element 30 is illustrated by a two-dot chain line, and a state after deflection occurs is illustrated by a solid line. The clearance S is provided between the outside element 30 and the inside element 40. The clearance S is a gap provided in a portion not concerning fitting of the outside element 30 and the inside element 40. The clearance S is set such that, even when deflection as illustrated occurs on the platen 20, in particular, on the outside element 30, an inner peripheral surface 38 defining the housing chamber 39 does not come into contact with the large-diameter portion 41 of the inside element 40.

With this configuration, deflection of the outside element 30 does not directly influence on deformation of the pressure ring 50. Therefore, even in the case where deflection occurs on the outside element 30 and the deflection (deflection amount) is varied due to variation (reduction) of the extruding force F, the die 60 disposed on the pressure ring 50 by the unillustrated holding means is not deformed as the second effect. Further, as described above, only the clearance satisfying the positioning criteria of the inside element 40 to the outside element 30 is provided between the outer diameter of the small-diameter portion 43 of the inside element 40 and the opening diameter of the holding hole 35 into which the small-diameter portion 43 is inserted. However, in the state where deflection occurs on the outside element 30, most part of an inner peripheral surface (inner peripheral surface of small-inner-diameter portion 36) of the opening of the outside element 30 into which the small-diameter portion 43 is inserted deforms in the direction separating from the outer peripheral surface of the small-diameter portion 43 of the inside element 40. Therefore, when deflection occurs on the outside element 30, smallness of the clearance does not influence on deformation of the pressure ring 50. Note that the predetermined clearance S and the deflection of the outside element 30 in FIG. 2 are exaggerated to facilitate understanding of the description.

On the other hand, during the extrusion process, rigidity to resist the bending moment M that causes deflection on the outside element 30, secured by maintaining the fastening state of the inside element 40 and the fastening member 46 at the substantially center part of the outside element 30 and maintaining the compression stress CF in the fastening state, can be structurally secured even when the inside element 40 is made of a metal material having a longitudinal elastic modulus substantially same as a longitudinal elastic modulus of the platen 20. Therefore, the inside element 40 is manufactured by a metal material greater in longitudinal elastic modulus than the platen 20, to improve the strength itself of the substantially center part of the platen 20 in addition to the compression stress CF generated at that center part. This makes it possible to further enhance the rigidity.

As described above, the tensile stress PF is generated in the inside element 40 and the compression stress CF is generated in the outside element 30 by the inside element 40 and the fastening member 46. This makes it possible to improve rigidity at the substantially center part of the outside element 30 and to suppress deflection (deflection amount) of the outside element 30 during the extrusion process.

Further, even when deflection (deflection amount) occurs on the outside element 30 and the deflection is varied during the extrusion process by variation (reduction) of the extruding force F, the predetermined clearance S is secured while being reduced by the configuration in which the outer peripheral surface of the large-diameter portion 41 of the inside element 40 and the inner peripheral surface of the holding hole 35 of the outside element 30 in which the large-diameter portion 41 is disposed do not come into contact with each other. Therefore, the deflection of the outside element 30 does not directly influence on deformation of the pressure ring 50.

As a result, as compared with the extrusion press machine disclosed in Patent Literature 1, deformation (deformation amount) of the pressure ring 50 and the die 60 and variation of the deformation can be considerably suppressed during the extrusion process, and it is possible to obtain the product extrusion-molded by the die 60, with desired dimensional accuracy from start to completion of the extrusion process.

Second Embodiment

Next, a platen 120 according to a second embodiment of the present invention is described with reference to FIG. 5 to FIG. 8.

As illustrated in FIG. 5 and FIG. 6, the platen 120 according to the second embodiment has a three-layer structure including a second outside element 130, a first outside element 140, and an inside element 150. The second outside element 130 is a rectangular parallelepiped member. The first outside element 140 and the inside element 150 are cylindrical members and are coaxially disposed on the center axis C. The first outside element 140 is fitted to an inside of the second outside element 130, and the inside element 150 is fitted to an inside of the first outside element 140. The inside element 150 is provided to sandwich the first outside element 140 from front and rear surfaces of the first outside element 140.

Second Outside Element 130

As illustrated in FIG. 5, FIG. 6, and FIG. 7, the second outside element 130 includes a thick portion 131 provided on the rear side, and a thin portion 133 continuous with the thick portion 131 and is provided on the front side. The second outside element 130 includes a holding hole 135 that is provided inside the thick portion 131 and the thin portion 133 and penetrates through the second outside element 130 in the front-rear direction. The first outside element 140 is fitted to the holding hole 135. The holding hole 135 includes a small-inner-diameter portion 136 corresponding to the thick portion 131, and a large-inner-diameter portion 137 corresponding to the thin portion 133, and is formed in a step shape in the front-rear direction.

First Outside Element 140

As illustrated in FIG. 5, FIG. 6, and FIG. 7, the first outside element 140 includes a small-diameter portion 141 provided on the rear side, and a large-diameter portion 143 continuous with the small-diameter portion 141 and is provided on the front side. The first outside element 140 includes a holding hole 145 that penetrates through the small-diameter portion 141 and the large-diameter portion 143. The adjacent inside element 150 is fitted to the holding hole 145. The holding hole 145 includes a small-inner-diameter portion 146 and a large-inner-diameter portion 147, and is formed in a step shape in the front-rear direction.

The second outside element 130 and the first outside element 140 are preferably fitted by shrinkage fit. When the second outside element 130 and the first outside element 140 are fitted by the shrinkage fit, compression stress is generated between the second outside element 130 and the first outside element 140 in a radial direction. Therefore, a portion including the second outside element 130 and the first outside element 140 is greater in rigidity than a case where the portion has an integrated structure. Further, when a longitudinal elastic modulus of a material configuring the first outside element 140 is greater than a longitudinal elastic modulus of a material configuring the second outside element 130, rigidity of the second outside element 130 can be further improved.

As described above, when the sufficient rigidity of the second outside element 130 is secured, the clearance S provided in the configuration of the first embodiment can be minimized or eliminated.

As the shrinkage fit, shrink fit and cooling fit are known. In a case where the shrink fit is adopted, the second outside element 130 and the first outside element 140 are fitted in a state where the second outside element 130 is heated to a predetermined temperature and is expanded in the radial direction. In a case where the cool fit is adopted, the second outside element 130 and the first outside element 140 are fitted in a state where the first outside element 140 is cooled to a predetermined temperature and is shrunk in the radial direction.

Inside Element 150

As illustrated in FIG. 5, FIG. 6, and FIG. 7, the inside element 150 includes a large-diameter portion 151 provided with an attachment concave portion for the pressure ring 50, and a small-diameter portion 153 continuous with the large-diameter portion 151 and penetrates through the housing chamber 39 in the front-rear direction.

The inside element 150 includes a discharge path 152 that penetrates through the inside element 150 from the large-diameter portion 151 to the small-diameter portion 153 in the front-rear direction. An extruded product extruded through the die 60 passes through the discharge path 152 and is discharged rearward from the extrusion press machine 1. The inside element 150 further includes a male thread 154 on an outer peripheral end on the rear side of the small-diameter portion 153. The male thread 154 of the small-diameter portion 153 is screwed with a female thread 157 of a fastening member 156. The inside element 150 further includes a pressure receiving surface 155 connecting the large-diameter portion 151 and the small-diameter portion 153. The pressure receiving surface 155 is a surface receiving pressure from the second outside element 130 and the first outside element 140 in a direction parallel to the center axis C.

The inside element 150 includes the fastening member 156 to fix the large-diameter portion 151 and the small-diameter portion 153 to the first outside element 140. The fastening member 156 has a form similar to a nut, and includes, on the inner peripheral surface, the female thread 157 to be fastened with the male thread 154 provided in the small-diameter portion 153. Also in the second embodiment, in a state where the preliminary load MF is generated during assembly of the extrusion press machine 1, the inside element 150 is disposed at the substantially center inner part of the platen 120 while tensile stress PF in the direction parallel to the center axis C is constantly generated in the inside element 150 by fastening the fastening member 156 in advance with the small-diameter portion 153 from the rear side of the platen 120.

The inside element 150 is fixed to the first outside element 140 while the tensile stress PF is generated in advance in the extrusion direction, by the preliminary load MF greater than or equal to the load acting in the extrusion direction during the extrusion process. The relationship is the same as the stress relationship between the outside element 30 and the inside element 40 in the first embodiment.

The inside element 150 includes fluid supply structures 160. As illustrated in FIG. 5, for example, the fluid supply structures 160 are provided at four positions with equal intervals in a circumferential direction.

As illustrated in FIG. 6 to FIG. 8, each of the fluid supply structures 160 includes a first structure 161 that supplies liquid fluid or gas fluid cooling the extruded product, and a second structure 165 that supplies air to form an air curtain.

The first structure 161 includes a first flow path 162 through which a cooling medium supplied from an unillustrated supply source flows, and first nozzles 163, 163 ejecting the cooling medium having flowed through the first flow path 162. The first flow path 162 extends inside the small-diameter portion 153 of the inside element 150 from the rear side toward the front side. The first nozzles 163, 163 are connected to front ends of the first flow path 162, and each have an ejection port directed to the inside in the radial direction of the small-diameter portion 153.

The second structure 165 includes a second flow path 166 through which the air supplied from an unillustrated supply source flows, and a second nozzle 167 provided at a front end of the second flow path 166. The second flow path 166 extends inside the small-diameter portion 153 of the inside element 150 from the rear side toward the front side. The second nozzle 167 is connected to the front end of the second flow path 166 and has an ejection port directed to the inside in the radial direction of the small-diameter portion 153.

The first structure 161 supplies the cooling medium to the extruded product having just passed through the discharge path 152, namely, immediately after being extruded, and cools the extruded product so as to follow a desired temperature history, which achieves effects of strength improvement and the like derived from hardening and other thermal treatment of the extruded product. The supplied cooling medium is selected from gas such as air and inert gas, and liquid such as water. In terms of cooling capacity, liquid, in particular, water is preferably sprayed.

When the liquid is used as the cooling medium, corrosion at a part where the sprayed liquid is adhered is concerned. For example, it is desirable to avoid occurrence of problem that the sprayed liquid adheres to the die 60 through the discharge path 152 of the inside element 150 and the passage 51 of the pressure ring 50, and the die 60 rusts or generated rust is mixed into the extruded product. Therefore, in the present embodiment, the second structure 165 is provided as a preferable form. In other words, the second structure 165 is provided on the front side close to the die 60 more than the first structure 161, and the air is supplied from the second structure 165 to form the air curtain that prevents the liquid sprayed from the first structure 161 from reaching the die 60.

In this example, the configuration in which the liquid is sprayed from the first structure 161 to the extruded product is described as the preferable form; however, gas may be sprayed from the first structure 161 to the extruded product. In this case, possibility of corrosion of the die 60 is eliminated. Therefore, the second structure 165 can be omitted.

Further, as illustrated in an upper diagram of FIG. 8, each of the fluid supply structures 160 may be provided such that the first nozzles 163 and the second nozzle 167 are exposed to the inside of the inside element 150 through short pipes. Alternatively, as illustrated in a lower diagram of FIG. 8, the first nozzles 163 and the second nozzle 167 may be provided in concave portions processed on the inner peripheral surface of the inside element 150. In a former case, a protector 164 covering the first nozzles 163 and the second nozzle 167 is preferably provided.

Effects by Second Embodiment

Next, effects by the second embodiment are described.

The platen 120 according to the second embodiment has the three-layer structure including the second outside element 130, the first outside element 140, and the inside element 150 in the radial direction, and the stress structure by sandwiching similar to that in the first embodiment is provided between the first outside element 140 and the inside element 150. Therefore, as in the first embodiment, deformation of the platen 120 during the extrusion process is suppressed.

Further, when the second outside element 130 and the first outside element 140 are fitted by shrinkage fit, compression stress in the radial direction is generated between the second outside element 130 and the first outside element 140. Therefore, the portion including the second outside element 130 and the first outside element 140 is greater in rigidity than the case where the portion has an integrated structure, and it is expected that deformation of the platen 120 during the extrusion process is further suppressed. As described above, when sufficient rigidity of the second outside element 130 is secured, the clearance S provided in the configuration of the first embodiment can be minimized or eliminated.

Further, in the second embodiment, since the fluid supply structures 160 are provided in the inside element 150, it is possible to secure rigidity of the second outside element 130 and the first outside element 140 of the platen 120 as described below.

For example, it is assumed that drilling is performed in order to form the first flow path 162 and the second flow path 166 of each of the fluid supply structures 160 around the discharge path 242 of the platen 220 that is wholly integrally configured as illustrated in FIG. 9. In this case, if the platen 220 is deflected, stress concentrates on drilled portions, which may cause breakage of the platen 220.

In place of the drilling, pipes configuring the first flow path 162 and the second flow path 166 may be disposed on a peripheral edge of the discharge path 242. To adopt the alternative, however, it is necessary to increase the opening diameter of the discharge path 242 in consideration of rising heights of cooling nozzles corresponding to the first nozzles 163 and the second nozzle 167. Therefore, when the alternative is adopted, rigidity of the platen 220 is deteriorated.

In contrast, in the second embodiment, the first flow path 162, the second flow path 166, the first nozzles 163, and the second nozzle 167 are disposed inside the inside element 150. At this time, as described above in the first embodiment (paragraph 0048), in the state where deflection occurs on the outside element 30 in the first embodiment, most part of the inner peripheral surface (inner peripheral surface of small-inner-diameter portion 36) of the opening of the outside element 30 into which the small-diameter portion 43 is inserted deforms in the direction separating from the outer peripheral surface of the small-diameter portion 43 of the inside element 40. Likewise, in a case where deflection occurs on the second outside element 130 in the second embodiment, most part of the inner peripheral surface (inner peripheral surface of small-inner-diameter portion 146) of the opening of the second outside element 130 into which the small-diameter portion 153 is inserted deforms in the direction separating from the outer peripheral surface of the small-diameter portion 153 of the inside element 150. Accordingly, in the inside element 150, stress concentration caused by deflection of the second outside element 130 does not occur, and deterioration of rigidity does not occur because of the tensile stress PF corresponding to the preliminary load MF greater than the rated load, constantly generated in the direction parallel to the center axis C of the inside element 150.

Further, the stress structure by sandwiching in which the portion including the small-diameter portion 141 of the first outside element 140 that is a part of the platen 120 is held by fastening of the inside element 150 and the fastening member 156, and the compression stress CF at the portion is maintained is provided similar to that in the first embodiment. The stress structure secures sufficient rigidity to resist the bending moment M causing deflection of the platen 120, which suppresses deflection itself of the platen 120 during the extrusion process. As a result, it is possible to avoid stress concentration on the first outside element 140 and the second outside element 130 provided outside the inside element 150, and to avoid deterioration in rigidity.

Further, the inside element 150 that is smaller in dimension and weight than the integrated platen 220 is easily drilled as compared with drilling of the platen 220.

Although the preferred embodiments of the present invention have been described above, the configurations described in the above-described embodiments can be selected or replaced with other configurations without departing from the gist of the present invention. For example, the fluid supply structures 160 can be provided in the inside element 40 in the first embodiment.

REFERENCE SIGNS LIST

• 1 Extrusion press machine
• 10 Extrusion unit
• 20 Platen
• 30 Outside element
• 31 Thick portion
• 32 Pressure receiving surface
• 33 Thin portion
• 33A Surface
• 33B Surface
• 35 Holding hole
• 36 Small-inner-diameter portion
• 37 Large-inner-diameter portion
• 38 Inner peripheral surface
• 39 Housing chamber
• 40 Inside element
• 41 Large-diameter portion
• 42 Discharge path
• 43 Small-diameter portion
• 45 Pressure receiving surface
• 46 Fastening member
• 46′ Fastening member
• 48 Attachment surface
• 50 Pressure ring
• 60 Die
• 70 Holding unit
• 71 Container
• 72 Holding chamber
• 73 Container holder
• 75 Container cylinder
• 76 Cylinder
• 77 Piston rod
• 80 Pressure generation unit
• 81 Main cylinder housing
• 83 Main cylinder
• 84 Main ram
• 85 Side cylinder
• 86 Main crosshead
• 87 Tie rod
• 88 Extrusion stem
• 89 Tie rod nut
• 120 Platen
• 130 Second outside element
• 131 Thick portion
• 133 Thin portion
• 135 Holding hole
• 136 Small-inner-diameter portion
• 137 Large-inner-diameter portion
• 140 First outside element
• 141 Small-diameter portion
• 143 Large-diameter portion
• 145 Holding hole
• 146 Small-inner-diameter portion
• 147 Large-inner-diameter portion
• 150 Inside element
• 151 Large-diameter portion
• 152 Discharge path
• 153 Small-diameter portion
• 155 Pressure receiving surface
• 156 Fastening member
• 160 Fluid supply structure
• 161 First structure
• 162 First flow path
• 163 First nozzle
• 165 Second structure
• 166 Second flow path
• 167 Second nozzle
• 220 Platen
• 242 Discharge path
• 250 Pressure ring
• 260 Die
• 287 Tie rod
• B Billet
• C Center axis
• S Clearance

Claims

1. An extrusion press machine, comprising:

a die configured to extrusion-mold a workpiece;

a cylinder configured to apply pressing force to press the workpiece against the die; and

a platen configured to receive the pressing force from the die, wherein

the platen includes:

an outside element; and

an inside element that is disposed coaxially with the outside element, inside the outside element, and

the inside element includes

one or more fluid supply structures each supplying a cooling medium toward an extruded product extruded from the die.

2. The extrusion press machine according to claim 1, wherein

each of the fluid supply structures includes a first structure supplying the cooling medium, and

the first structure includes a first flow path through which the cooling medium flows, and a first nozzle ejecting the cooling medium having flowed through the first flow path.

3. The extrusion press machine according to claim 2, wherein

each of the fluid supply structures includes a second structure supplying air to form an air curtain,

the second structure includes a second flow path through which the air flows, and a second nozzle ejecting the air having flowed through the second flow path, and

the second nozzle is provided on a side close to the die more than the first nozzle.

4. The extrusion press machine according to claim 2, wherein the fluid supply structures are provided with equal intervals in a circumferential direction.

5. The extrusion press machine according to claim 2, wherein

the inside element includes a large-diameter portion provided on a front side, and a small-diameter portion continuous with the large-diameter portion, and

the first flow path extends inside the small-diameter portion from a rear side to the front side, and the first nozzle has an ejection port directed to an inside in a radial direction of the small-diameter portion.

6. The extrusion press machine according to claim 3, wherein

the inside element includes a large-diameter portion provided on a front side, and a small-diameter portion continuous with the large-diameter portion, and

the second flow path extends inside the small-diameter portion from a rear side to the front side, and the second nozzle has an ejection port directed to an inside in a radial direction of the small-diameter portion.

7. The extrusion press machine according to claim 3, wherein the air curtain is formed to prevent liquid as the cooling medium ejected from the first nozzle, from reaching the die.

8. The extrusion press machine according to claim 3, wherein, in each of the fluid supply structures,

the first nozzle and the second nozzle are provided to be exposed to an inside of the inside element through short pipes, or

the first nozzle and the second nozzle are provided in concave portions provided on an inner peripheral surface of the inside element.

9. The extrusion press machine according to claim 1, wherein the inside element is provided to sandwich the outside element from front and rear surfaces of the outside element.

10. The extrusion press machine according to claim 9, wherein the inside element is disposed inside the outside element while tensile stress is generated in advance in an axial direction by a preliminary load greater than or equal to a load acting during an extrusion process.

11. The extrusion press machine according to claim 1, wherein the inside element is made of a metal material that has a longitudinal elastic modulus substantially same as or greater than a longitudinal elastic modulus of the outside element.

12. A platen for an extrusion press machine, the platen being configured to receive pressing force in extrusion molding by a die, the platen comprising an outside element and an inside element that is disposed coaxially with the outside element, inside the outside element, wherein

the inside element includes one or more fluid supply structures each supplying a cooling medium toward an extruded product extruded from the die.