Abstract:
Provided is a short stroke type extrusion press which is capable of increasing a container strip force, improving energy efficiency, and saving space by reducing apparatus length. A main cylinder housing ( 4 ) of the extrusion press comprises a transfer medium ( 10 ) which advances or retreats an extrusion stem ( 13 ) in an extrusion axis direction, and a transfer medium ( 16 ) which advances or retreats a container ( 14 ) in the extrusion axis direction. A container pushing medium ( 21 ) is disposed at an end platen ( 1 ) disposed opposite the main cylinder housing ( 4 ) and makes it possible for at least four different transfer motions to be carried out independently or in collaboration with the container transfer medium in the direction in which the container ( 14 ) separates from a die ( 9 ).

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    The present invention claims priority from, and incorporates by reference the entire disclosure of, Japanese Patent Application No. 2011-173675, filed on Aug. 9, 2011. 
       TECHNICAL FIELD 
       [0002]    The present invention relates to an extrusion press which is used for extrusion of aluminum alloy or another metal, more particularly relates to a short stroke type extrusion press which shortens the machine length to save space and relates to an extrusion press which is designed for multiple functions and shortens the idle time. 
       BACKGROUND ART 
       [0003]    In general, when extruding an material to be extruded (billet) made of a metal material, for example, aluminum or an alloy material of the same etc., by an extrusion press, a stem is attached to a front end of a main ram which is driven by a hydraulic pressure cylinder. The material to be extruded (billet) is placed in a container by a placement means in a state where the container is pushed against a die. In addition, by further advancing the main ram by driving the hydraulic cylinder, the material to be extruded (billet) is extruded by the stem. Therefore, a shaped product is extruded from the outlet part of the die. 
         [0004]      FIG. 2  shows the configuration of a conventional short stroke type extrusion press which shortens the machine length so as to save space. Reference numeral  1  of  FIG. 2  indicates an end platen,  2  a die slide which is provided with a die  9  for extrusion of a product,  3  a container holder which holds a container  14  which stores a material to be extruded (billet)  12 ,  4  a main cylinder housing,  5  a main cylinder,  6  a main ram,  7  a main crosshead which is integrally attached to the front end of the main ram  6 , and  10  side cylinders which are used for movement of the main crosshead  13  and are provided at the right-left horizontal outside surface part of the main cylinder  5 . 
         [0005]    At the front end of the main crosshead  7 , a stem slider  11  is attached slidably in the horizontal direction perpendicular to the advancing/retracting direction of the main crosshead  7 , that is, the axial direction. At one end of the stem slider, an extrusion stem  13  which extends to the end platen side is attached. This extrusion stem  13  can move by a not shown stem slide cylinder between the press center and a standby position of the extrusion stem which is offset from the center position. 
         [0006]    The material to be extruded (billet)  12  is supplied by a not shown extruded material (billet) supplying means to the space which was formed by movement of the extrusion stem and is stored in the container by an extruded material (billet) pushing means. 
         [0007]    In the container  14 , first ends of container cylinder rods  15  are attached to the container holder  3 . The other ends of these container cylinder rods  15  are connected to container cylinders  16  which are provided at the top-bottom vertical outside surface part of the main cylinder  5 . Due to the supply of hydraulic fluid to the container cylinders  16 , the container  14  can be moved between the die  9  and the extrusion stem  13  (see PLT 1). 
         [0008]    The container cylinders  16  operate in an advancing/retracting operation where they advance to abut against the die  9  so that the end face of the container  14  at the extrusion stem side and the extrusion stem  13  move to form a clearance so as to obtain a space for supplying the material to be extruded (billet)  12 , an advancing/retracting operation in an air exhaust process in which compressed air which remains inside the container  14  after upset is exhausted, a strip operation of a container  14  which strips discard after the extrusion process ends during which the container  14  retracts to secure a clearance for a shear blade  28  to move up and down between an end face of the container  14  at the die side and the die  9 , and an operation where when the die  9  is to be replaced, the container  14  retracts to secure a clearance for a die slide operation between the end face of the container  14  at the die side and the die  9  in which the die slide  2  can horizontally move. Further, it also operates in equal pressure extrusion control which renders constant the container sealing force which would otherwise fall along with the progress in the extrusion process. 
         [0009]    In this regard, in the above conventional extrusion press, the container cylinders  16  are configured attached to the main cylinder housing  4  in this way, so there is the problem that, due to interference with other parts at the extrusion press and other mechanisms and other factors, increasing a container strip force is accompanied with difficulties in design strength and structure. 
         [0010]    Further, since the above operations are performed by the container cylinders  16 , there is the problem that a large amount of hydraulic fluid is supplied, useless energy is consumed, and the energy efficiency is poor. 
       CITATIONS LIST 
     Patent Literature 
       [0011]    PLT 1: Japanese Patent Publication No. H8-206727A 
       SUMMARY OF INVENTION 
     Technical Problem 
       [0012]    The present invention is made to solve the above problem and has as its object to provide a short stroke type extrusion press which increases the container strip force, improves the energy efficiency, shortens the machine length, and saves space. 
       Solution to Problem 
       [0013]    To achieve the above object, an extrusion press as set forth in a first aspect of the present invention is an extrusion press comprising a moving means which advances and retracts an extrusion stem in an extrusion axial direction and a moving means which advances and retracts a container in the extrusion axial direction, characterized in that a container pushing means which enables at least four different types of movement operations in a direction in which the container separates from the die alone or in cooperation with the container moving means is provided at an end platen which is arranged facing the main cylinder housing. 
         [0014]    The extrusion press as set forth in a second aspect of the present invention provides the invention as set forth in the first aspect characterized in that the four types of movement operations are an air exhaust operation which exhausts compressed air in the container which has been formed in an upset process, an equal pressure extrusion operation which renders a container sealing force which acts on the container constant during an extrusion process, a discard strip operation which strips discard of the billet after the end of the extrusion operation from the inside of the container, and a die opening operation which provides a clearance between an abutting end face of the die and end face of the container when replacing the die after the end of an extrusion cycle. 
         [0015]    The extrusion press as set forth in a third aspect of the present invention provides the invention as set forth in the first aspect characterized in that the container pushing means is configured by a plurality of hydraulic cylinders which are smaller in diameter than the container moving means. 
       Advantageous Effects of Invention 
       [0016]    According to the present invention, hydraulic cylinders which assist movement of the container when making the container move in the retracting direction are provided at the end platen, so, without impairing the strength of the main cylinder housing, the design is simplified and the container strip force for the discard strip operation can be increased. 
         [0017]    Further, the container pushing means is configured using hydraulic cylinders which are smaller in diameter than the container moving means, so when making the container retract, supply of a small amount of hydraulic fluid is sufficient, the required drive force can be slashed, and the energy efficiency can be improved. 
         [0018]    The present invention will become more clearly understood from the attached drawings and the explanation of preferred embodiments of the present invention. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0019]      FIG. 1  is a longitudinal cross-sectional view of an extrusion press which explains an embodiment of the present invention. 
           [0020]      FIG. 2  is a longitudinal cross-sectional view of a conventional extrusion press. 
       
    
    
     DESCRIPTION OF EMBODIMENTS 
       [0021]    Below, the present invention will be explained in detail based on  FIG. 1 .  FIG. 1  shows an embodiment of an extrusion press of the present invention, where  1  indicates an end platen,  2  a die slide which is provided with a die  9  for product extrusion,  3  a container holder which holds a container  14  which stores material to be extruded (billet)  12 ,  4  a main cylinder housing,  5  a main cylinder,  6  a main ram,  7  a main crosshead which is integrally attached to a front end of the main ram  6 , and  10  side cylinders which are used for movement of the main crosshead  13  and are provided at the left-right horizontal outside surface part of the main cylinder  5 . 
         [0022]    At the front end part of the main crosshead  7 , a stem slider  11  is attached to be slidable in a vertical or horizontal direction perpendicular to the advancing/retracting direction of the main crosshead  7 , that is, the axial direction. At one end of the stem slider  11 , an extrusion stem  13  is attached extending to the end platen side. This extrusion stem  13  can be moved by a not shown stem slide cylinder between a press center and an extrusion stem standby position offset from the center position. 
         [0023]    The material to be extruded (billet)  12  is placed on the front end part of a not shown extruded material (billet) supplying means, is supplied to a space which is formed by movement of the extrusion stem, and is stored in a container  14  by a pushing means of a material to be extruded (billet)  12  which is provided at the front end of a not shown extruded material (billet) supplying means. 
         [0024]    In the container  14 , first ends of container cylinder rods  15  are attached to the container holder  3 . The other ends of these container cylinder rods  15  are connected to container cylinders  16  which are provided at the top-bottom vertical outside surface part of the main cylinder  5 . Due to the supply of hydraulic fluid to the container cylinders  16 , the container  14  can be moved between the die  9  and the extrusion stem  13 . 
         [0025]    Reference numeral  21  is a container pushing means which is mainly comprised of assist cylinders  22  and assist cylinder rods  23 . The assist cylinders  22  are attached at the end platen  1  symmetrically with the axial direction of the extrusion press to be able to push the container  14  in the direction of the extrusion stem  13 . Reference numeral  18  shows seats for the assist cylinder rods  23  which are provided extending to the container holder  3 . Further, the extrusion press is provided with a not shown position detecting means for detecting the amount of movement of the container holder  3 . Due to the assist cylinders  22 , the container holder  3  is controlled to a predetermined amount of movement. This enables adjustment of the amount of opening of the container holder  3 . 
         [0026]    Reference numeral  27  indicates a main shear device adapted to cut away the not shown discard of the material to be extruded (billet)  12  by moving a shear blade  28  down into the clearance between the die  9  and the container  14 , after the material to be extruded (billet)  14  finishes being extruded, then the extrusion stem  13  retracts by the operation of the side cylinders  10 , and then the container  14  retracts by the operations of the container cylinders  16  and assist cylinders  22 . 
         [0027]    In the discard strip operation, the extrusion stem  13  holds its position, only the container holder  3  is opened by a predetermined amount, then the container holder  3  and the extrusion stem  13  are simultaneously retracted. 
         [0028]    The assist cylinders  22  are configured in a pair facing the outer edges of the die at a slant as explained above, but four assist cylinders  22  may also be provided to push the container  14 . 
         [0029]    The action of the container pushing means  21  in the extrusion press which is configured in this way will be explained. 
         [0030]    For the air exhaust operation, at the start of the extrusion process, the material to be extruded (billet)  12  which is made slightly smaller in diameter than the inside diameter of the container is stored in the container  14 , then the material to be extruded (billet)  12  is pushed by the extrusion stem  13  against the die  9  inside of the container  14  for so-called upset, the material to be extruded (billet)  12  is crushed and the air between the container  14  and the material to be extruded (billet)  12  is compressed. To release this compressed air, hydraulic fluid is supplied to the head side of the assist cylinders  22  to retract the container holder  3  and the extrusion stem  13  is retracted to draw out the compressed air from the clearance between the die  9  and container  14 . At this time, the container holder  3  and the container cylinder rods  15  are pushed by the assist cylinder rods  23  and retracted. The compressed air is released, then the container cylinders  16  and the side cylinders  10  are used to again advance the container  13  and the extrusion stem  13  to start the extrusion process. 
         [0031]    In the extrusion process, the material to be extruded (billet)  12  in the container  14  gradually becomes shorter in length, so at the time of start of the extrusion process and the time of end of the extrusion process, usually the former is larger in force of extrusion action. That is, even if the extrusion resistance of the die  9  is constant, the frictional resistance of the container  14  and the material to be extruded (billet)  12  becomes smaller as the material to be extruded (billet)  12  is reduced in length, so overall force of the extrusion action ends up falling. This fall in the force of the extrusion action causes a reduction in the container sealing force on the die  9  and causes deformation of the shape of the die  9  and a change in the dimensions and shape of the product. 
         [0032]    This equal pressure extrusion operation supplies hydraulic fluid to the head sides of the assist cylinders  22  (and rod side of container cylinder) when there is a change in the dimensions and shape of the extruded product in this way, pushes the container holder  3  in a direction opposite to the extrusion to reduce the container sealing force which excessively acts on the die  9  from the time of extrusion start to the middle of the extrusion process, and controls the container sealing force which acts on the die  9  during the extrusion process so as to become constant from the time of extrusion start to the time of extrusion end. 
         [0033]    Due to the discard strip operation, after the end of the extrusion process, after the material to be extruded (billet)  12  finishes being extruded, the side cylinders  10  are operated to make the extrusion stem  13  retract while hydraulic fluid is supplied to the container cylinders  16  and the assist cylinders  22  at the head side so that the container  14  is also retracted to pull out discard from the container  14 . Further, the shear blade  28  is made to descend in the clearance formed between the die  9  and the container  14  to cut the discard. After cutting the discard, the shear blade  28  is made to rise. 
         [0034]    When the discard is pulled out from the container  14  (discard strip operation), the moving means of the assist cylinders  22  and container cylinders  16  are used. 
         [0035]    In the case of the die opening operation, the die is made to move horizontally along with the die slide  2  when changing the shape of the product or when the die  9  becomes worn and is replaced. At this time, hydraulic fluid is supplied to the head sides of the assist cylinders  22  to retract the container housing  3  and thereby secure a clearance between the die  9  and the container  14 . 
         [0036]    In the above four operations, in each case, hydraulic fluid is supplied to the head sides of the assist cylinders  22  to retract the container holder  3 . Further, the rods of the assist cylinders  22  may be pulled back by the method of supplying hydraulic fluid to the rod sides of the assist cylinders  22 , the method of being pushed back by the advancing container cylinders  16  through the container holder  3 , etc. 
         [0037]    The container strip force in the present invention is the working force which pulls out the discard from the container. 
         [0038]    The strokes of the assist cylinders  22  are adjusted by control based on the amount of detection of a not shown position detecting means which detects the amount of movement of the container holder  3 , but, for example, it is also possible to provide a stroke adjustment mechanism which enables mechanical control of the strokes at the assist cylinders  22  and perform control by adjustment to predetermined strokes for each operation. 
         [0039]    As explained above, in the extrusion press of the present invention, the end platen is provided with a plurality of assist cylinders which assist the retraction operation of the container (movement to extrusion stem side) and which are smaller in diameter than the container cylinders and smaller in output. 
         [0040]    For this reason, in the air exhaust operation and die opening operation which are smaller in load of movement of the container, it is possible to reduce the amount of supply of hydraulic fluid required for retracting the container and possible to save energy and shorten the operating time. 
         [0041]    Further, at the time of the equal pressure extrusion and discard strip operation which are large in load of movement of the container, the container cylinders and assist cylinders cooperate in output, so design is facilitated and the container strip force can be increased without impairing the strength of the main cylinder housing. 
         [0042]    The present invention was explained by reference to a specific embodiment selected for the purpose of explanation, but it will be clear to a person skilled in the art that a large number of modifications are possible without departing from the basic idea and scope of the present invention. 
       REFERENCE SIGNS LIST 
       [0043]      1  end platen 
         [0044]      2  die slide 
         [0045]      3  container holder 
         [0046]      4  main cylinder housing 
         [0047]      5  main cylinder 
         [0048]      6  main ram 
         [0049]      7  main crosshead 
         [0050]      9  die 
         [0051]      10  side cylinder 
         [0052]      11  stem slider 
         [0053]      12  material to be extruded (billet) 
         [0054]      13  extrusion stem 
         [0055]      14  container 
         [0056]      15  container cylinder rod 
         [0057]      16  container cylinder 
         [0058]      21  container pushing means 
         [0059]      22  assist cylinder 
         [0060]      23  assist cylinder rod 
         [0061]      27  shear device 
         [0062]      28  shear blade