Abstract:
A container degassing device for an extrusion press is equipped with: a integrally formed degassing block joined to the end surface of the container of the extrusion press; a first sealing member that seals the degassing block; a second sealing member that seals the outer peripheral surface of an extrusion stem or a fixed dummy block of the extrusion press; and a vacuum suction device that sucks air from within a degassing space formed within the container. The degassing space is sealed by the degassing block and the first and second sealing members, and the area between the degassing block and the container end surface is sealed by a metal touch.

Description:
TECHNICAL FIELD 
       [0001]    The present invention relates to a container degassing device of an extrusion press. 
       BACKGROUND ART 
       [0002]    If loading into a container a billet with a diameter slightly smaller than an inside diameter of the container, then pushing the billet in the container by a rear extrusion stem against a die to cause so-called “upsetting”, the billet is crushed and the air between the container and billet is compressed. The method of providing a degassing device for discharging this compressed air from a fixed dummy block side of the extrusion stem to the outside of the container which comprises, for example, to be able to move in an axial direction of the extrusion stem, a ring-shaped seal part which is provided at an extrusion stem-side end face of a container which has a container liner in which a billet is loaded, a seal block which is split in two in a direction crossing an axial direction of the extrusion stem, and a pushing device which, when closing the seal block, can make a side end face of the ring-shaped seal part and an outer circumferential surface of the extrusion stem simultaneously closely contact each other through a seal member which is attached to an abutting surface of the seal block and a seal member which is provided at an extrusion stem-side end face of the seal block and which pushes a seal member which is provided at a container-side end face of the seal block against the ring-shaped seal part and of sealing the inside of the container by a seal material while sucking out and removing the air from the gap between the fixed dummy block outer circumferential surface and the container inner circumference wall surface is disclosed in PLT 1. 
       CITATIONS LIST 
     Patent Literature 
       [0003]    PLT 1: Japanese Patent Publication No. 10-128432A 
       SUMMARY OF INVENTION 
     Technical Problem 
       [0004]    In the past, seal members, such as heat resistant rubber (silicone etc.) have been used for sealing a container end face and an extrusion stem outer circumferential surface. Due to the high temperature or the abrasion caused by movement of the extrusion stem etc., the seal material quickly deteriorated, the sealability became poor, and variations arose in the vacuum degree in the container, so the seal material had to be frequently changed. In a conventional extrusion press, a seal block loading device, opening/closing device, etc., are provided. The installation space for the extrusion press apparatus became larger and simultaneously the apparatus became complicated. Maintenance took time. 
       Solution to Problem 
       [0005]    To solve this problem, the present invention provides a container degassing device of an extrusion press comprising a one-piece degassing block which is joined with an end face of a container of the extrusion press, a first seal member which closely contacts the degassing block, a second seal member which closely contacts an outer circumferential surface of a fixed dummy block or extrusion stem of the extrusion press, and a vacuum suction device which sucks out air in a degassing space which is formed in the container, wherein the degassing space is tightly closed by the degassing block and the first and second seal members, and the degassing block and the container end face are tightly closed by metal-to-metal contact. 
         [0006]    In the present invention, the degassing block can have at least one hole for removing air which is communicated with the degassing space and fluidly connected to the vacuum suction device, the first seal member can be configured to tightly close the degassing block by metal-to-metal contact, and, when degassing the degassing space, the atmospheric pressure outside the degassing space can act on the first and second seal members so that the tight closure of the degassing space is improved. 
         [0007]    In the present invention, the first seal member and the second seal member may contact each other and the second seal member may receive force from the first seal member. 
         [0008]    The present invention further provides a container degassing device of an extrusion press comprising a one-piece degassing block which is joined with an end face of a container of the extrusion press, a first seal member which closely contacts the degassing block, at least one second seal member which closely contacts an outer circumferential surface of a fixed dummy block or extrusion stem of the extrusion press, and a vacuum suction device which sucks out air in a degassing space which is formed in the container, wherein the first and second seal members can move relative to the extrusion stem, the degassing space is tightly closed by the degassing block and the first and second seal members, and the degassing block and the container end face are tightly closed by metal-to-metal contact. 
         [0009]    In the present invention, the degassing device can further comprise pushing frames which make the first seal member move to push against the degassing block and are operated by fluid cylinders, the first seal member and the second seal member can contact each other, and the second seal member can receive force through the first seal member from the pushing frames. 
         [0010]    In the present invention, the pushing frames may move up and down together with the extrusion stem and may be provided with turn stoppers. 
         [0011]    In the present invention, a container-side end face of the degassing block may be provided with a cut groove for removing air. 
         [0012]    Further, to solve the above problem, there is provided an extrusion pressure which comprises a degassing means of a container which has means for sealing the container end face and the outer circumferential surface of the extrusion stem, wherein a one-piece degassing block is made to abut against the container end face by metal-to-metal contact and wherein a vacuum pump etc. is used to remove the air from the inside of the container. 
         [0013]    A through hole for removing air is drilled through the degassing block, a space which is surrounded by the degassing block seal member which is made to abut by the metal-to-metal contact is degassed by a vacuum pump, etc., and the force of atmospheric pressure is utilized to give sealability and evacuate the space to vacuum. 
         [0014]    The space which is surrounded by the degassing block and the seal member which abuts against a fixed dummy block or extrusion stem is degassed by vacuum. 
         [0015]    Still further, to solve the above problem, the present invention provides an extrusion press comprising a degassing means of a container which has a means for tightly closing a container end face and an outer circumferential surface of an extrusion stem, which makes a one-piece degassing block abut against a container end face by metal-to-metal contact and removes air from a degassing space which is surrounded by the degassing block and a movable seal member which abuts against a fixed dummy block or extrusion stem using a vacuum pump etc. 
         [0016]    The movable seal member is moved by pushing frames which can move by fluid cylinders and are pushed against the degassing block for the seal. 
       Advantageous Effects of Invention 
       [0017]    The one-piece degassing block is made to abut against the container end face and tightly closes it by metal-to-metal contact, so the seal member made of the elastic material which is required for that part in the conventional device becomes unnecessary. Further, if making the first seal member for example one made of a nonferrous metal material and tightly closing the degassing block by metal-to-metal contact, it becomes possible to greatly reduce the frequency of replacement of the seal member. 
         [0018]    In the past, a two-piece split degassing block has been loaded by a loading device or joined by an opening/closing device, but in the present invention, the loading device and opening/closing device of the degassing block are no longer necessary, space saving can be realized, and the apparatus can be simplified thereby facilitating maintenance, etc. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0019]      FIG. 1  is a cross-sectional view of a side view which shows an outline of a part from an end platen to an extrusion stem of an extrusion press according to a first embodiment of the present invention. 
           [0020]      FIG. 2A  is an enlarged view of a part A 1  of  FIG. 1 . 
           [0021]      FIG. 2B  is a cross-sectional view along X-X of  FIG. 2A  seen toward an extrusion direction. 
           [0022]      FIG. 3  is an enlarged view of a part A 2  of  FIG. 1 , similar to  FIG. 2A , of an extrusion press according to a second embodiment of the present invention. 
           [0023]      FIG. 4  is an enlarged view of a part A 3  of  FIG. 1 , similar to  FIG. 2A , of an extrusion press according to a third embodiment of the present invention. Note that, the part A 1 , the part A 2 , and the part A 3  show different embodiments of the same location. 
           [0024]      FIG. 5  is an operational flow chart of an extrusion press according to the first to third embodiments of the present invention. 
           [0025]      FIG. 6  is a cross-sectional view of a side view which shows an outline of a part from a die to a main crosshead of a front loading extrusion press of a fourth embodiment of the present invention and a view of the state of the inside of the container being degassed. 
           [0026]      FIG. 7  is a detailed view of a part P of  FIG. 6  where the seal member abuts against the degassing block and further the seal member is pushed by a pushing member in the pushing direction. 
           [0027]      FIG. 8  is a view of the cross-section along X-X of  FIG. 6  as seen from the arrow direction and shows details of the pushing member and pushing frames. 
           [0028]      FIG. 9  is a cross-sectional view of a side view of an extrusion press the same as  FIG. 6  and a cross-sectional view when the pushing action is completed. 
           [0029]      FIG. 10  is a cross-sectional view of a side view of an extrusion press the same as  FIG. 6  and a view right before supplying a billet to a container. 
           [0030]      FIG. 11  is an operational flow chart of a front loading extrusion press according to a fourth embodiment. 
           [0031]      FIG. 12  is a cross-sectional view of a side view of principal parts of a front loading extrusion press according to a fifth embodiment and a view of the state of the inside of the container being degassed. 
           [0032]      FIG. 13  is a view of the cross-section along Y-Y of  FIG. 12  as seen from the arrow direction. A pipeline for removing the air in the container is shown shifted from the position of the extrusion lever. 
           [0033]      FIG. 14  is a cross-sectional view of a side view of principal parts of a rear loading (stem slide) extrusion press according to a sixth embodiment and a view right before supplying a billet to a container. 
           [0034]      FIG. 15  is an operational flow chart of a rear loading extrusion press according to a sixth embodiment. 
           [0035]      FIG. 16  is a cross-sectional view of a plan view which shows an outline of the part from the die to the main crosshead of a rear loading extrusion press according to a seventh embodiment. 
           [0036]      FIG. 17  is a view of the cross-section along Z-Z of  FIG. 16  as seen from the arrow direction and shows the state of the pushing frames when the stem slide is at the center of the extrusion press. 
           [0037]      FIG. 18  is a view of the cross-section along Z-Z of  FIG. 16  as seen from the arrow direction and shows the state of the pushing frames when the stem slide is at a raised position. 
       
    
    
     DESCRIPTION OF EMBODIMENTS 
       [0038]    In an extrusion pressure according to a first embodiment of the present invention, as shown in  FIG. 1 , there is a die  14  sandwiched between an end platen  11  and a container  12  which comprises a container liner  12   a , container tire  12   b , and container holder  12   c . The die  14  is held by fitting its outer circumference slidably into an inner circumferential surface of a not shown die ring. 
         [0039]    Degassing space  16  is the clearance between the inner circumference wall surface of the container liner  12   a  and the outer circumferential surface of the billet  17 . On the other hand, at a front end of an extrusion stem  21  which pushes in a billet  17 , a fixed dummy block  20  which can closely contact the inner circumference wall surface of the container liner  12   a  by extension and retraction of the outer circumference front end part is provided. 
         [0040]    Reference numeral  18  is an extruded material obtained by crushing of the billet  17  and extrusion from the die  14  along with advance of the extrusion stem  21 . 
         [0041]    A degassing means  19  for tightly closing the degassing space  16  and sucking out the air at the inside in the present embodiment will be explained. 
         [0042]    First, the degassing means  19  for sucking out the air from the extrusion stem  21  side in the container  12  is provided with a degassing block  22  which is arranged at the extrusion stem  21  side end face of the container  12  and is joined in a direction crossing the axial direction of the extrusion stem  21 . It is configured to make the degassing block  22  closely contact the outer circumferential surface of the fixed dummy block  20  or extrusion stem  21  and make the degassing block  22  closely contact the container end face and fasten it by bolts  23  to tightly seal the container  12 . 
         [0043]    The degassing means  19  has a vacuum suction device  24 . The vacuum suction device  24  is provided with a pressure sensor  25 , piping  26 , solenoid valve  27 , vacuum tank  28 , vacuum pump  29 , etc., and is designed to be communicated with the degassing space  16  through the degassing means  19  and the piping  26  when sucking out the air at the inside of the container  12 . 
         [0044]    The degassing means  19  also has means, i.e., seal members, for realizing air-tightness between the degassing block  22  and fixed dummy block  20  or extrusion stem  21 . These are shown in  FIG. 2A  and  FIG. 2B . 
         [0045]    In  FIG. 2A  and  FIG. 2B , a combination of nonferrous metal ring-shaped seal members  31 ( a ),  31 ( b ) fixed by a plurality of bolts  34  with springs  35  to the degassing block  22  and a seal member  31 ( c ) made of a heat resistant elastic material or nonferrous metal material is used to tightly close the degassing space  16 . 
         [0046]    In  FIG. 3  which shows a second embodiment, a combination of an L-cross-section ring-shaped seal member  41 ( a ) fixed by a plurality of bolts  44  with springs  45  to the degassing block  22 , a ring shaped substantially frustoconical cross-section seal member  41 ( b ) of for example a nonferrous metal material, and a seal member  41 ( c ) made of a heat resistant elastic material are used to tightly close the degassing space  16 . 
         [0047]    In  FIG. 4  which shows a third embodiment, the degassing block  22  and the fixed dummy block  20  or extrusion stem  21  are configured to tightly close the degassing space  16  which is sealed by a seal member  51  made of a heat resistant elastic material or nonferrous metal material. 
         [0048]    Next, the extrusion operations of extrusion presses according to the first to third embodiments will be explained based on the operational flow chart of  FIG. 5 . 
         [0049]    In the initial state, the container  12  and the extrusion stem  21  retract in the anti-extrusion direction. 
         [0050]    First, to start, a not shown billet loader supplies a billet  17  between the die  14  and the fixed dummy block  20  over the axial line of the extrusion stem  21  (S 1 ). Next, the extrusion stem  21  advances whereby the billet  17  is held between the die  14  and the fixed dummy block  20  (S 2 ). Next, the billet loader moves to the outside of the extrusion press, and then pressurized oil is fed to a not shown container cylinder, whereby the container  12  advances (S 3 ). 
         [0051]    In this state, the air in the degassing space  16  in the container  12  starts to be removed (S 4 ). When the vacuum value of the degassing space  16  reaches the target value (detected by the pressure sensor  25  (S 5 )), the upsetting operation of the billet  17  is started (S 6 ). When the pressure of the upsetting reaches the target value (S 7 ), the degassing space  16  finishes being degassed (S 8 ) and simultaneously the extrusion is started (S 9 ). 
         [0052]    The timing of startup of the vacuum suction device  24 , that is, the start of degassing, may be any of a timing before the start of the upsetting operation after loading the billet  17  in the container  12 , simultaneous with the start, or after the elapse of a certain time after the start of the upsetting operation. A suitable start timing for the various conditions of the extrusion is selected. The degassing is ended after it is detected that the degassing space  16  has reached a predetermined vacuum degree. 
         [0053]    After detecting that the upsetting operation of the billet  17  has been completed, extrusion is started along with advance of the extrusion stem  18  and the extruded material  18  is extruded from the die  14 . 
         [0054]    After the extrusion ends (S 10 ), the container  12  retracts just slightly and the not shown discard is separated from the container (S 11 ). Next, the container  12  and the extrusion stem  21  simultaneously retract to the point of time of start (S 12 ). Therefore, a not shown discard shear descends and cuts off the discard (S 13 ). 
         [0055]    Due to the above, one cycle of extrusion is ended (S 14 ) and the next cycle is proceeded to. 
         [0056]    The degassing block  22  which is shown in  FIG. 1  will be explained. The degassing block  22  is fabricated as a one-piece donut shape by a ferrous material. It is formed with one or more through holes for sucking out the air in the degassing space  16  by a vacuum suction device  24 . 
         [0057]    Formation of a plurality of through holes gives a larger pipeline cross-sectional area and enables the degassing space  16  to reach a vacuum state faster. Due to this, it becomes possible to make the degassing block  22  thinner. As a result, it is possible to shorten the length of the extrusion stem  21 . 
         [0058]    The degassing block  22  is fixed to the container  12  by bolts  23  or other fastening parts. 
         [0059]    The degassing block  22  and the container  12  are sealed by metal-to-metal contact, so the contact surface of the degassing block is finished to a fine surface roughness of an extent enabling a seal. Alternatively, it may be possible to provide a projecting part at the metal-to-metal contact surface of the degassing block  22 , provide a recessed part at the contact surface of the container  12 , provide this projecting part and recessed part at one location or several locations as the metal-to-metal contact surface, and thereby give sealability to the metal-to-metal contact. 
         [0060]    The enlarged view of the part A 1  of the first embodiment which is shown in  FIG. 2A  will be explained. The seal member  31 ( a ) and the seal member  31 ( b ) are fabricated by nonferrous metal and are made ring shaped. The seal member  31 ( a ) and the seal member  31 ( b ) are welded together etc. to form an integral structure. The seal member  31 ( a ) forms a clearance with the degassing block  22  at the vertical surface, while the seal member  31 ( b ) forms metal-to-metal contact with the degassing block  22  at its tapered surface. The respective metal-to-metal contact surfaces are finished to a fine enough surface roughness enabling a seal. The seal member  31 ( a ) is fixed to the degassing block  22  at several locations by bolts  34  or other fastening parts with springs  35 . The seal member  31 ( c ) is made of a heat resistant elastic material or nonferrous metal. When the seal member  31 ( c ) is a nonferrous metal, it may be made an integral part with the seal member  31 ( b ). The seal member  31 ( c ) may be a material which has heat resistance, for example, silicone rubber or fluororubber, processed into a sponge-like sheet shape. 
         [0061]    The degassing block is formed with one or more through holes  38 , in the latter case for minimizing the thickness dimension of the degassing block, for sucking out the air to create a vacuum by the vacuum suction device  24 . Therefore, if using the vacuum suction device  24  to suck out the air to create a vacuum, the degassing space  16  becomes a vacuum state, the seal member  31 ( b ) is acted on by atmospheric pressure such as shown by the arrow mark, and the sealability of the tapered surface of the seal member  31 ( b ) and that of the seal member  31 ( c ) is improved. Note that, for that purpose, the seal member  31 ( b ) has to be made thin. 
         [0062]    The enlarged view of the part A 2  of the second embodiment which is shown in  FIG. 3  will be explained. The seal member  41 ( a ) which has an L-cross-section and is fabricated by a ring-shaped nonferrous metal may be joined with the degassing block  22  at the tapered surface by metal-to-metal contact. The seal member  41 ( a ) is fixed to the degassing block  22  by a fastening part, such as a bolt  44  with a spring  45  which is sealed by a nonmetal elastic material  48 . The substantially frustoconical cross-section, ring shaped seal member  41 ( b ) joins the degassing block  22  and the seal member  41 ( a ) at their tapered surfaces by metal-to-metal contact. This may also be combined with the heat resistant elastic material or nonferrous metal seal member  41 ( c ) to exhibit close adhesion and hold the vacuum of the degassing space  16 . When the seal member  41 ( c ) is a nonferrous metal, it may also be formed integrally with the seal member  41 ( b ). The seal member  41 ( c ) may also be a material which has heat resistance, for example, silicone rubber or fluororubber, which is processed into a sponge-like sheet shape. 
         [0063]    The degassing block  22  is provided with one or more through holes  46  for sucking out air by the vacuum suction device  24 . One or more degassing passages  47  are formed from these through holes to the chamber  49 . Therefore, if sucking out the air to create a vacuum by the vacuum suction device  24 , the chamber  49  also becomes a vacuum state, the seal member  41 ( b ) is acted on by atmospheric pressure such as shown by the arrow mark, and the sealability is improved. 
         [0064]    Therefore, for the seal of the outer circumferential surface of the extrusion stem  21 , due to the wedge effect of the seal member  41 ( b ), an action of pushing the seal member  41 ( c ) from the outer circumference is obtained and an improvement in the sealability can be realized. 
         [0065]    Note that, for that purpose, the seal members  41 ( a ) and  41 ( b ) have to be made thin. 
         [0066]    The enlarged view of the part A 3  of the third embodiment which is shown in  FIG. 4  will be explained. The degassing block and the fixed dummy block  20  or extrusion stem  21  are sealed by the seal member  51 . 
         [0067]    The seal member  51  is preferably made of a material which has heat resistance, for example, a nonferrous metal. Alternatively, it may be made of silicone rubber or fluororubber processed into a sponge-like sheet shape. 
         [0068]    The air of the degassing space  16  passes through the through holes  52  and is sucked out by the vacuum suction device  24  to create a vacuum. 
         [0069]    The one-piece degassing block is made to abut against the container end face, a vacuum pump etc. is used to remove the air in the container, the degassing block is formed with through holes for degassing use, and the space surrounded by the degassing block and the seal member abutting against it by metal-to-metal contact is given sealability utilizing the force of atmospheric pressure and degassed to create a vacuum, so a high vacuum with no variation can be maintained for a long period of time in the container. 
         [0070]    As a result, air is no longer entrained in the extruded product, blisters and oxides are no longer formed, the yield is improved, and simultaneously there is no longer a burp cycle, the idle time becomes shorter, and the productivity is improved. 
         [0071]    Further, the one-piece degassing block is made to abut against the container end face, and the seal member is also made to contact it by metal-to-metal contact, so frequent replacement of the seal member becomes unnecessary and the time for replacement of the seal member can be shortened. In the past, a two-piece split degassing block has been conveyed by a conveyor device or joined by an opening/closing device, but in the present invention, the conveyor device or opening/closing device of the degassing block becomes unnecessary, space saving can be realized, cost can be reduced, and maintenance etc. become easy due to simplification of the structure. 
         [0072]    Below, a fourth embodiment to a seventh embodiment will be explained. The fourth embodiment and the fifth embodiment relate to a front loading extrusion press, while the sixth embodiment and the seventh embodiment relate to a rear loading extrusion press. 
         [0073]      FIG. 6  is a cross-sectional view of a side view which shows the part from the die to the main crosshead of an extrusion press according to the fourth embodiment. 
         [0074]    Reference numeral  11  indicates a die. The die  11  is slidably held by being fit at its the outer circumference at the inner circumferential surface of a not shown die ring. The degassing space  15  is the clearance between the inner circumference wall surface of the container liner  13   b  and the outer circumferential surface of the billet  16 . On the other hand, at the front end of the extrusion stem  18  which pushes in the billet  16 , a fixed dummy block  17  which can tightly contact the inner circumference wall surface of the container liner  13   b  by expansion and contraction of the outer circumference front end part is provided. 
         [0075]    A not shown extruded material is extruded from the die  11  by crushing of the billet  16  along with advance of the extrusion stem  18 . 
         [0076]    A degassing means  20  for tightly closing the degassing space  15  and sucking out the air inside it in the fourth embodiment will be explained next. 
         [0077]    First, the degassing means  20  for sucking out the air from the extrusion stem  18  side of the container  13  is provided with a degassing block  21  which is arranged at the extrusion stem  18  side end face of the container  13  and which is joined in the direction crossing the axial direction of the extrusion stem  18 . The degassing means  20  is also provided with a seal member  23  which is pushed against the degassing block  21  and a seal member  24  which abuts against the outer circumferential surface of the fixed dummy block  17  or extrusion stem  18 , and makes the degassing block  21  closely contact the container end face and fastens it by bolts  25  to tightly seal the container  13 . 
         [0078]    The degassing means  20  also has a vacuum suction device  26 . The vacuum suction device  26  is provided with a pressure sensor  27 , piping  31 , solenoid valve  28 , vacuum tank  29 , vacuum pump  30 , etc. and is configured to communicate with the degassing space  15  through the degassing means  20  and the piping  31  when sucking out the air inside of the container  13 . 
         [0079]    The degassing block  21  which is shown in  FIG. 6  will be further explained. The degassing block  21  is fabricated as a one-piece donut shape by a ferrous material. It is formed with one or more degassing passages  32  for sucking out the air in the degassing space  15  by a vacuum suction device  26 . 
         [0080]    Formation of a plurality of degassing passages  32  gives a larger pipeline cross-sectional area and enables the degassing space  15  to reach a vacuum state faster. Due to this, it becomes possible to make the degassing block  21  thinner. As a result, it is possible to shorten the length of the extrusion stem  18 . 
         [0081]    The degassing block  21  is fixed to the container  13  by bolts  25  or other fastening parts. 
         [0082]    The degassing block  21  and the container  13  are sealed by metal-to-metal contact, so the contact surface of the degassing block  21  is finished to a fine surface roughness of an extent enabling a seal. Alternatively, it may be possible to provide a projecting part at the metal-to-metal contact surface of the degassing block  21 , provide a recessed part at the contact surface of the container  13 , provide this projecting part and recessed part at one location or several locations as the metal-to-metal contact surface, and thereby give metal-to-metal contact sealability. 
         [0083]    The seal members  23  and  24  in the fourth embodiment of the present invention are shown in  FIG. 7 . The seal member  23  is ring shaped in form with a substantially frustoconical cross-section. This seal member  23  is made by a nonferrous metal. 
         [0084]    The surface abutting against the fixed dummy block  17  or extrusion stem  18  is sealed by the heat resistant seal member  24  at one or more locations. The seal member  24  preferably uses an elastic material which has heat resistance or a nonferrous metal material. 
         [0085]    The seal member  23  has a tapered surface at the surface abutting against the degassing block  21  and seals it by metal-to-metal contact, so the seal member  23  is finished to a fine enough surface roughness so that the surface abutting with the degassing block  21  can be sealed. 
         [0086]    Note that, the tapered surface of the other end of the seal member  23  is pushed against by the pushing member  41 , whereby the sealability with the degassing block  21  can be improved and the seal member  23  can be made to move in the extrusion direction. In the figure, reference numeral  22  is a cut groove which is formed at the container side end face of the degassing block  21  and enlarges the cross-sectional area of the passage from the degassing space to the degassing passage. As a result, the degree of vacuum of the degassing space is quickly raised. 
         [0087]    The degassing means  20  is further provided with a pushing frame device which is shown in  FIG. 6 ,  FIG. 7 , and  FIG. 8 . This pushing frame device will be explained next.  FIG. 8  is a cross-sectional view of a pushing frame device as seen along the arrow X-X of  FIG. 6 . Clevices  43  are fixed to the front ends of rods  44  of hydraulic cylinders  45  which are fastened to a main crosshead  48 . From the clevices  43 , pushing frames  42  and a pushing member  41  are connected. 
         [0088]    As shown in  FIG. 8 , the pushing frames  42  are provided in sets of two. Two or more sets are combined for assembly. 
         [0089]    As shown in  FIG. 7 , the pushing member  41  pushes against the seal member  23  in the extrusion direction in the state which is shown in the illustration so as to improve the sealability. 
         [0090]    In the figure, one set each of the pushing frames  42  is provided above and below the axial center of the extrusion press, but it is also possible to provide one set each at the left and right of the axial center of the extrusion press. 
         [0091]      FIG. 9  shows the state of the seal member  23  and the pushing frame device when the extrusion operation is completed. 
         [0092]    After starting extrusion, the hydraulic cylinders  45  are set in a free state without sending pressurized oil. At this time, the seal member  23  is in a state abutting against the degassing block  21 , so does not move in absolute position, but the extrusion stem  18  advances in the extrusion direction, so the relative position of the seal member  23  with the extrusion stem  18  changes from the initial position of the fixed dummy block  17  gradually in the direction of the position of the extrusion stem  18  and reaches the position of the extrusion stem  18  when the extrusion ends. After that, when the extrusion stem  18  retracts, the seal member  23  retracts while maintaining its position. 
         [0093]    That is, the seal member  23  moves back and forth on the fixed dummy block  17  and the extrusion stem  18  at the above position. 
         [0094]      FIG. 10  is a schematic view at the time of loading a billet  16  in a front loading extrusion press. In the figure, a not shown billet loader is used to load a billet  16  between the die  11  and the fixed dummy block  17 . At this time, the pushing frames  42  stand by at the retraction limit at the anti-extrusion side. Next, the extrusion stem  18  advances and the billet  16  is clamped between the die  11  and the fixed dummy block  17 . Next, the billet loader retracts to outside the machine and a not shown container cylinder is used to make the container  13  move in the extrusion direction and abut against the die  11 . After that, the pushing frames  42  advance while pushing the seal member  23  in the extrusion direction and make the seal member  23  abut against the degassing block  21 . 
         [0095]    Next, the extrusion operation of a front loading extrusion press according to the fourth embodiment will be explained based on the operational flow chart of  FIG. 11 . 
         [0096]    At the initial state, the container  13  and the extrusion stem  18  retract in the anti-extrusion direction. 
         [0097]    First, to start, a not shown billet loader supplies a billet  16  between the die  11  and the fixed dummy block  17  over the axial line of the extrusion stem  18  (S 1 ). Next, the extrusion stem  18  advances and the billet  16  is held between the die  11  and the fixed dummy block  17  (S 2 ). Next, the container  13  is advanced to seal the die  11  by the container  13  and simultaneously the seal member pushing frames  42  are made to advance (S 3 ). Next, the seal member pushing frames  42  are used to push the seal member  23  against the degassing block  21  to complete the seal (S 4 ). 
         [0098]    In this state, air starts to be removed from the degassing space  15  inside of the container  13 . First, the degassing valve  28  is turned on (S 5 ), then the air starts to be removed from the degassing space  15  (S 6 ). After the vacuum value of the degassing space  15  reaches the target value (detected at pressure sensor  25  (S 7 )), the upsetting operation of the billet  16  is started (S 8 ). When the upsetting pressure reaches the target value (S 9 ), the air finishes being removed from the degassing space  15  (S 10 ) and simultaneously extrusion is started (S 11 ). 
         [0099]    After the extrusion starts, the pushing frames retract (S 12 ). After the extrusion operation ends (S 13 ), the container  13  is made to retract just slightly (S 14 ). After that, the container  13  and the extrusion stem  18  retract (S 15 ). Next, a not shown discard shear is used to cut off the discard (S 16 ). With the above, the cycle ends (S 17 ) and the next cycle is proceeded to. 
         [0100]    Below, the fifth embodiment will be explained. Configurations the same as the fourth embodiment are assigned the same reference numerals. Different structures are assigned reference numerals in the 100s or 200s. 
         [0101]      FIG. 12  shows a front loading extrusion press in which pushing cylinders  150  are fastened to the container  13  according to the fifth embodiment. In the case of a front loading extrusion press, if the pushing cylinders  45  are fastened to the main crosshead  48 , it is necessary to lengthen the stroke of the hydraulic cylinder  45 , while with a system where the pushing cylinders  150  are fixed to the container  13 , the stroke of the pushing cylinders  150  can be made short. This apparatus is designed so that the hydraulic cylinders  150  push by a short stroke against an extrusion lever  152  which is supported by a shaft so as to abut against the seal member  23 . 
         [0102]    In the present configuration, when replacing the container  13 , the fixed dummy block  17  and the extrusion stem  18  have to be detached. For that purpose, the two ends of the extrusion lever  152  have to be made free, so the pushing member  41  side of the extrusion lever  152  and the front end part  150  of the hydraulic cylinder  150  are fastened by key plates  155   a ,  155   b . When replacing the container  13 , the key plate  155   a  and pushing members  41  and the key plates  155   b  and front end parts  153  of the hydraulic cylinders  150  are designed to be able to be detached at any time to enable the container  13  to be replaced. 
         [0103]      FIG. 13  is a view of a cross-section along Y-Y of  FIG. 12  as seen from the arrow direction and shows the state of degassing passages  132  and a pipeline  131 . 
         [0104]    In the case of the present configuration, the degassing passages  132 , pipeline  131 , etc. are set at slightly tilted positions avoiding the positions of the extrusion lever  152  etc. 
         [0105]      FIG. 14  is a schematic view of a rear loading extrusion press (stem slide) according to the sixth embodiment at the time of loading a billet  16 . In the figure, drive cylinders  45  of the pushing frame device are fastened to a stem slide  49 . In the figure, first the extrusion stem  18  and the hydraulic cylinders  45  which are fastened to the stem slide  49  stand by above the axial line of the container  13 . Simultaneously, the seal member  23  stands by above in the same way at a rear position of the extrusion stem  18 . First, to start, a billet  16  is loaded by a not shown billet loader above the axial line of the container  13 . Next, an insertion device of the billet loader is used to insert the billet  16  into the container  13 . Next, the billet loader retracts to outside the machine. After that, the stem slide  49  descends to the axial center of the container, then the pushing frames  42  advance, whereby the seal member  23  abuts against the degassing block  21  and the extrusion stem  18  advances to the upsetting position. 
         [0106]    Next, the extrusion operation of a rear loading extrusion press according to the sixth embodiment will be explained based on the operational flow chart of  FIG. 15 . 
         [0107]    In the initial state, the extrusion stem  18  stands by above the center of the extrusion press, while the container  13  is retracted in the anti-extrusion direction. 
         [0108]    First, to start, the container  13  advances and seals the die  11  end face (S 1 ). Next, a not shown billet loader is used to supply a billet  16  above the axis of the container  13  (S 2 ). Next, the billet loader inserts the billet  16  into the container  13 . After that, the billet loader retracts to outside the machine. Next, the extrusion stem  18  moves to the position of the center of the extrusion press (S 4 ). 
         [0109]    Next, the pushing frames  42  advance simultaneously with the extrusion stem  18  advancing (S 5 ). The billet  16  strikes the die  11  and pushes the seal member  23  against the degassing block  21  to complete the seal (S 6 ). 
         [0110]    In this state, the air in the degassing space  15  in the container  13  starts to be removed. First, the degassing valve  28  is turned on (S 7 ), then the air in the degassing space  15  starts to be removed (S 8 ). When the vacuum value of the degassing space  15  reaches the target value (detected by pressure sensor  25  (S 9 )), the upsetting operation of the billet  16  is started (S 10 ). When the pressure of the upsetting operation reaches the target value (S 11 ), the degassing space  15  finishes being degassed (S 12 ) and simultaneously extrusion is started (S 13 ). 
         [0111]    When extrusion is started, the seal member pushing frames retract (S 14 ). After extrusion ends (S 15 ), the container  13  is made to retract just slightly (S 16 ). After that, the container  13  and the extrusion stem  18  retract (S 17 ). Next, a not shown discard shear is used to cut off the discard (S 18 ). Due to the above, one cycle is completed (S 19 ) and the next cycle is proceeded to. 
         [0112]      FIG. 16  is a schematic view of a rear loading extrusion press according to the seventh embodiment as seen from a plan view at the time of loading a billet  16 . In the case of this figure, hydraulic cylinders  245  which drive the pushing frames  242  are fastened to stem slide guides  66  and a main crosshead  48 . The pushing frames  242  are not fastened with rods  243  of the drive-use hydraulic cylinders  245  and separate from the hydraulic cylinders  245  when the extrusion stem  18  rises. When the pushing frames  242  separate from the hydraulic cylinders  245 , they rotates around the extrusion stem  18 , so fastening pins  262  are attached to the pushing frames  242  as turn stoppers. The fastening pins  262  are inserted into fastening pin insertion holes  267  provided in the extrusion stem fastening parts  268  whereby the pushing frames  242  can move to the raised position without rotating. 
         [0113]      FIG. 17  is a view of the cross-section along Z-Z of  FIG. 16  as seen from the arrow direction and shows the state of the pushing frames  242  when the stem slide  49  is at the center of the extrusion press. 
         [0114]    The two end faces of the pushing frames  242  abut so that the rods  243  of the hydraulic cylinders  245  are clenched, but they are not fastened to them, so when moving to the raised position, the pushing frames  61  separate from the rods  243  of the hydraulic cylinders  245 . 
         [0115]    Further, these are attached to be able to advance and retract in the longitudinal direction of the extrusion press by the hydraulic cylinders  245 . 
         [0116]      FIG. 18  is a view of the cross-section along Z-Z of  FIG. 16  as seen from the arrow direction and shows the state of the pushing frames  242  when the stem slide  49  is at the raised position. When the pushing frames  242  are at the raised position, the fastening pins  262  of the pushing frames  242  are inserted into the fastening pin insertion holes  267  at the extrusion stem fastening parts  268 , so the pushing frames  242  will not rotate. 
         [0117]    The one-piece degassing block is made to abut against the container end face, and the space which is surrounded by the degassing block and a movable seal member which abuts against the fixed dummy block or extrusion stem is degassed by a vacuum pump etc., so it becomes possible to realize long maintenance of a high degree of vacuum free of variation inside the container. 
         [0118]    As a result, air is no longer entrained in the extruded product, blisters and oxides no longer form, the yield is improved, simultaneously burp cycles are eliminated, the idle time becomes shorter, and the productivity is improved. 
         [0119]    Further, the one-piece degassing block is made to abut against the container end face and the seal member is also made to contact by metal-to-metal contact, so frequent replacement of the seal member becomes unnecessary and the replacement time of the seal member can be shortened. In the past, the two-piece split degassing block has been loaded by a loading device and joined by an opening/closing device, but in the present invention, the loading device and opening/closing device of the degassing block are no longer necessary. It is possible to realize space savings and the costs are reduced and the structure simplified, so maintenance etc. become easy. 
         [0120]    Note that, the present invention is described in detail based on specific embodiments, but a person skilled in the art can made various changes, corrections, etc. without departing from the claims and concepts of the present invention.