Abstract:
In a method for operating an indirect extrusion press, wherein the indirect extrusion press includes an indirect punch having a tool head that can be accommodated on the indirect punch, a closure piece, and a longitudinally movable block holder having a material block accommodation for accommodating a material block, after pressing a material block and forming a shell in a shell chamber, a tool head to be replaced is pushed out of the block holder by a tool head to be inserted, so that very operationally reliable removal of a shell formed during one or more pressing procedures is possible. For this purpose, an indirect extrusion press can have a maximal distance between a closure piece and an indirect punch that corresponds at least to the sum of the expanses of the tool head and of the block holder in the movement direction.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    Applicant claims priority under 35 U.S.C. §119 of German Application No. 10 2013 008 345.1 filed May 16, 2013, the disclosure of which is incorporated by reference. 
       BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The invention relates to a method for operation of an indirect extrusion press and an indirect extrusion press. 
         [0004]    2. Description of the Related Art 
         [0005]    During indirect pressing of crude metal blocks, the forming procedure to produce the pressed product takes place with the formation of a shell, for example. The crude metal blocks may be made, for example, of copper, brass or corresponding alloys, and the shell is formed in order to avoid contaminants on the surface of the block to be formed from getting into the finished pressed product. In this connection, a tool head comprising a die plate is kept smaller in its diameter than the inside diameter of a block, to such an extent that a shell having a wall thickness of about 0.2 mm to 2.0 mm remains on the inner wall of the block holder, in each instance, as is also disclosed, for example, in EP 0 224 115 B1. The formation of a shell can also be correspondingly advantageous in the case of other materials, for example aluminum. 
         [0006]    In this connection, a distinction should be made between direct and indirect pressing procedures, whereby in direct pressing, larger pressed products can generally be produced, with guidance of a pressing punch and of the metal to be formed in the same direction. In indirect pressing, in which the pressing punch is called an indirect punch and the material are guided in opposite directions, significantly lower friction forces generally occur, because the material does not need to be displaced relative to the block holder. In general, however, only smaller pressed products can be produced in indirect pressing, because the pressed product must be discharged through the indirect punch. 
         [0007]    To reduce material tensions in the indirect punch, DE 101 31 901 A1 proposes screwing a clearing ring onto the indirect punch and relieving stress with a counter-nut. Alternatively, a wear plate and/or a die plate is attached by way of insertion bolts that are shrunk-fit into corresponding bores of the indirect punch. 
         [0008]    After one or more pressing procedures, the shell that has formed as a result of pressing of the block material must generally be removed, in order to be able to implement operationally reliable pressing for subsequent pressing procedures. In known methods, in order to remove the shell, the latter is pulled out of the block holder together with the tool head, accompanied by great disassembly effort and assembly effort. Almost complete removal of the shell from the block holder, without remnant, however, is not possible in this way. Moreover, a remaining remnant of the shell has a detrimental effect on subsequent pressing procedures or on the operational reliability of subsequent pressing procedures. This detrimental effect results because the remaining remnant can lead, particularly during pressing, to undesirable block compression of the metal block or material block during the loading procedure that is intended for the subsequent pressing procedure. Furthermore, the remaining remnant of the shell can hinder secure introduction of a new tool head or of a cleaned or repaired tool head into the block holder. In particular, the tool head can become jammed on the remaining remnant. 
       SUMMARY OF THE INVENTION 
       [0009]    It is the task of the present invention to indicate a method for the operation of an indirect extrusion press and an indirect extrusion press, with which operationally reliable removal of a shell that has been formed during one or more pressing procedures is possible. 
         [0010]    This task is accomplished with a method for operation of an indirect extrusion press in accordance with one aspect of the invention, and with an indirect extrusion press in accordance with another aspect of the invention. Further advantageous embodiments are found in the following description. 
         [0011]    In the operation of an indirect extrusion press, operationally reliable removal of the shell can be implemented, as compared with known methods, using the following steps,
   (A) bringing the indirect punch out of the material block accommodation by moving the block holder in the direction of the closure piece,   (B) placing a further tool head between indirect punch and material block accommodation and accommodating the further tool head on the indirect punch,   (C) introducing the indirect punch, together with the accommodated further tool head, into the material block accommodation, and bringing the further tool head into contact with the other tool head, by moving the block holder in the opposite direction, and   (D) pushing the other tool head out of the material block accommodation by moving the block holder further in the opposite direction, whereby the shell is pressed out of the material block accommodation, in part or in its entirety, during the further movement, by the further tool head.   
 
         [0016]    In the known methods, a shell that has been formed by means of pressing of the material block(s) is removed, in complicated manner, by means of pulling the tool head, in each instance, out of the block holder. In contrast to the known methods, significantly more operationally reliable removal of the shell can be implemented by means of providing Steps A to D, particularly in that according to Step D, the shell or the shell that has formed can be pressed out of the material block accommodation, in part or in its entirety, by means of pushing the other tool head out of the material block accommodation, as provided. This reliability is particularly a consequence of the circumstance that pressing the shell out of the material block accommodation can be undertaken by the further tool head, in guided manner, in the material block accommodation. Complicated removal by means of pulling or partially pulling the shell out of the block holder together with the tool head, as provided in known methods—which is possible only with the acceptance of a certain unavoidable lack of operational reliability, such as, for example, the tool head falling out or tilting—can be advantageously eliminated. 
         [0017]    The shell can furthermore be advantageously removed from the block holder or from the material block accommodation without remnant or almost without remnant, by means of suitable process management, particularly during the implementation of Step D. 
         [0018]    Particularly by introducing the indirect punch, together with the accommodated further tool head, into the material block accommodation, and bringing the further tool head into contact with the other tool head by moving the block holder in the opposite direction, as undertaken in (C), it can be ensured that the further tool head performs a movement with regard to the block holder that corresponds to its movement during indirect pressing itself. As a result, possible shell remnants within the block holder are also treated in operationally reliable manner, just like the pressed material itself, in the case of suitable process management. In particular, a peeling ring of the further tool head can act accordingly on possible remnants within the material block. 
         [0019]    If, in Step D, during the further movement, the shell is partially pressed out of the material block accommodation by the further tool head, then in Step D, after the shell is partially pressed out of the material block accommodation, an excess length formed by means of the shell being partially pressed out can be separated from a remnant of the material. This method of procedure is particularly advantageous if the existence of a certain remnant of the material cannot be avoided due to default values of the design or process technology, or if such a remnant is actually desired. It is particularly advantageous that the excess length can be sheared off by means of a shearing blade in order to separate it. 
         [0020]    In Step B of the method, the further tool head can be disposed between indirect punch and material block accommodation block holder by a manipulator of an industrial robot, and accommodated on a further tool head. Step B can be carried out with very great process reliability by means of the use of a manipulator. 
         [0021]    In Step D, the other tool head can be pushed into a predetermined position on a manipulator or in the surroundings of a manipulator of an industrial robot when it is pushed out. Subsequently, the other tool head can be grasped by the manipulator and moved away from the block holder. Step D can also be carried out with very great process reliability by the use of the manipulator of an industrial robot in Step D. 
         [0022]    A high degree of automation can also be advantageously achieved by means of suitable inclusion in the entire method sequence, on the basis of provision of a manipulator in Steps B and C, in the manner described above. 
         [0023]    Operationally reliable removal of the shell can particularly be implemented cumulatively or alternatively to the above explanations, by means of an indirect extrusion press that comprises an indirect punch having a tool head that can be accommodated on the indirect punch, a closure piece, and a longitudinally movable block holder having a material block accommodation for accommodating a material block. The block holder can be moved in a straight line, in a movement direction, by the closure piece, by way of the indirect punch. The indirect punch can be brought out of the material block accommodation by moving the block holder in the direction of the closure piece and introduced into the accommodation by being moved in the opposite direction. The closure piece can be moved in a straight line from a maximal position with a maximal distance from the indirect punch toward the indirect punch. The indirect extrusion press is characterized in that in the maximal position, the maximal distance between the closure piece and the indirect punch corresponds at least to the sum of the expanses of the tool head and of the block holder in the movement direction. 
         [0024]    By means of providing this maximal distance, Step B of the above method can be carried out in operationally reliable manner, in simple manner, and thereby also operationally reliable removal of a shell that has been formed can be made possible. Operationally reliable implementation of Step B is made possible in that undisturbed placement of the further tool head between indirect punch and material block accommodation can be guaranteed by means of the maximal distance made available, if the closure piece is in the maximal position or was previously moved into this maximal position. Nevertheless, other ways of managing the method, which might not be quite as operationally reliable, are also possible. For example, a tool head may be at first ejected entirely and subsequently a new tool head may be inserted, after the block holder was displaced as far as possible in the direction of the closure piece. 
         [0025]    Particularly preferably, the maximal distance is configured to be more than 2 mm greater than the sum, in order to be able to carry out the placement of the further tool head between indirect punch and material block accommodation in Step B of the method in very operationally reliable manner and, in particular, with sufficient play. In particular, a distance of 4 mm, in total, is advantageous for an operationally reliable sequence, so that 2 mm distance are available on both sides of the tool head on both sides, in each instance, for a normal tool head replacement. 
         [0026]    Preferably, the tool head can have a conical section that narrows in the pressing direction of the indirect extrusion press or in the opposite direction. This section is provided for forming a shell chamber of the indirect extrusion press, which chamber is delimited by the narrowing section and the inner wall of the material block accommodation that delimits the material block accommodation. By means of providing the narrowing conical section, the tool head can advantageously be released from the clamping by the shell, specifically particularly by means of pushing the tool head out of the material block accommodation counter to the pressing direction, as is particularly provided for the other tool head in Step D. 
         [0027]    Preferably, the indirect punch comprises a peeling ring that delimits the shell chamber in the pressing direction and can be released from the tool head. In this manner, separation of the tool head from the peeling ring or from the indirect punch can be undertaken in very simple manner. Likewise, it is easily possible to place a new tool head in front of the peeling ring. 
         [0028]    It is understood that the characteristics of the solutions described above and in the claims can also be combined, if necessary, in order to be able to implement the advantages in correspondingly cumulative manner. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0029]    Further advantages, goals, and properties of the invention will be explained using the following description of exemplary embodiments, which are particularly also shown in the attached drawing. The drawing shows: 
           [0030]      FIG. 1  is a schematic representation of an indirect extrusion press, together with a material block intended for pressing; 
           [0031]      FIG. 2  is a schematic representation of the indirect extrusion press according to  FIG. 1  in an operating state in which a section of the material block was already pressed to form a pressed product; 
           [0032]      FIG. 3  is a schematic representation of the indirect extrusion press according to  FIGS. 1 and 2  in an operating state in which the material block was already completely pressed to form a pressed product; 
           [0033]      FIGS. 4-8  are each a schematic representation of the indirect extrusion press according to  FIGS. 1 to 3 , having two tool heads, whereby the representations are provided to illustrate an exemplary embodiment of the method for operating an indirect extrusion press; 
           [0034]      FIG. 9  shows the indirect extrusion press of  FIGS. 1 to 8  together with a material block in a block loading position for preparing for a pressing procedure. 
       
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
       [0035]    The exemplary embodiment of an indirect extrusion press  10  shown in  FIG. 1  comprises an indirect punch  12  having a tool head  14  that can be accommodated on the indirect punch  12 , a pressing punch  13  having a closure piece  16 , and a longitudinally movable block holder  18  having a material block accommodation  20  for accommodating a material block  22 . The indirect punch  12  furthermore comprises a peeling ring  42 . 
         [0036]    The material block  22  that can be pressed to produce a pressed product by means of the indirect extrusion press  10  is a material block  22  that can consist, at least in part or in its entirety, of a metallic material, such as, for example, aluminum, copper, brass or corresponding alloys. 
         [0037]    The block holder  18  can be moved in a straight line by the closure piece  16 , by way of the indirect punch  12 . The indirect punch  12  can be brought out of the material block accommodation  20  by moving the block holder  18  in the direction of the closure piece  16 . Therefore the indirect punch  12  can be introduced into the material block accommodation  20  by moving the block holder  18  in the opposite direction (see, in this regard, also  FIG. 4 ). Because essentially relative movements are involved, in this connection, it is understood that in deviating embodiments, the indirect punch can also be movable, while other modules are merely configured to be stationary. 
         [0038]    In the operating state illustrated in  FIG. 2 , a section of the material block  22  introduced into the material block accommodation  20  was already pressed to produce a pressed product  17  in the form of a tube, by being pressed through a die plate  19  of the tool head  14 , by means of displacement of the block holder  18  and of the material block  22  by means of the closure piece  16  or by means of the pressing punch  13 ; this product was discharged by way of a cavity  15  provided in the indirect punch  12 . 
         [0039]      FIG. 3  illustrates the operating state of the indirect extrusion press  10  in which the material block  22  was completely pressed to produce a pressed product  17 . The shearing blade  34  provided serves for shearing off a pressing remnant  35  formed during the pressing procedure, after being stripped out or pressed out of the material block accommodation  20  by the tool head  14  or the block holder  18 , and, in this connection, separating it from a shell  24  that is also formed during the pressing procedure, which is situated in a shell chamber  26  of the indirect extrusion press  10 , whereby the shell chamber  26  is disposed radially around the tool head  14 . 
         [0040]    To form the shell chamber  26 , the tool head  14  has a conical section  38  that narrows in the pressing direction of the indirect extrusion press  10  or in the opposite direction, whereby the shell chamber  26  is delimited by the narrowing section  38  and the inner wall  40  of the material block accommodation  20 , in other words the inner wall  40  that delimits the material block accommodation  20 . 
         [0041]      FIGS. 4 to 8  serve to illustrate an exemplary embodiment of the method for operating the indirect extrusion press  10 . After the material block  22  is pressed and the shell  24  is formed in the shell chamber  26 , Steps A to D explained in greater detail below are provided in the exemplary embodiment of the method to be illustrated here. 
         [0042]    Thus,  FIG. 4  illustrates the situation or the operating state after Step A has been carried out and while Step B of the method is being carried out. In other words, what is illustrated in  FIG. 4  is the situation or the operating state after the indirect punch  12  has been brought out of the material block accommodation  20  by moving the block holder  18  in the direction of the closure piece  16  and after a further tool head  28  has been placed between indirect punch  12  and material block accommodation  20 , but before accommodating the further tool head  28  on the indirect punch  12 . 
         [0043]    In the situation shown in  FIG. 4 , the closure piece  16  is situated in a maximal position with a maximal distance between the closure piece  16  and the indirect punch  12 , whereby the closure piece  16  or the pressing punch  13  can be moved in a straight line from the maximal position toward the indirect punch  12 . A material block  22  can be introduced into the material block accommodation  20  by means of moving the closure piece  16  or the pressing punch  13  toward the indirect punch  12 , whereby this functionality of the closure piece  16  or the pressing punch  13  is required for pressing the material block  22 , in each instance (see also  FIG. 2 ). 
         [0044]    In order to implement problem-free or operationally reliable placement of the further tool head  28  between indirect punch  12  and material block accommodation  20 , and also problem-free or operationally reliable accommodation of the further tool head  28  on the indirect punch  12 , the maximal distance is preferably configured to be 7% greater than the sum of the expanses of the tool head  14  and of the block holder  18  in the movement direction, in other words in the direction in which the block holder  18  can be moved in a straight line by the closure piece  16 , by way of the indirect punch  12 . 
         [0045]      FIG. 4  also illustrates, although only schematically, that in Step B, the further tool head  28  is placed between the indirect punch  12  and the material block accommodation  20  by a manipulator  36  of an industrial robot, which is shown very schematically, and accommodated on the further tool head  28 . 
         [0046]      FIG. 5  illustrates the situation or the operating state after Step C of the method has been carried out, whereby Step C comprises introducing the indirect punch  12 , together with the accommodated further tool head  28 , into the material block accommodation  20 , and bringing the further tool head  28  into contact with the other tool head  14  by means of moving the block holder  18  in the opposite direction—here, in other words, by moving it away from the closure piece  16 . 
         [0047]      FIG. 6  illustrates the situation or the operating state of the indirect extrusion press while Step D of the method is being carried out or undertaken. Step D comprises pushing the other tool head  14  out of the material block accommodation  20  by means of moving the block holder  18  further in the opposite direction, whereby the shell  24  is partially pressed out of the material block accommodation  20  during the further movement, by means of the further tool head  28 . In this connection,  FIG. 6  illustrates the situation in which Step D has not yet been completely concluded, particularly the situation in which the shell  24  is still disposed in the material block accommodation  20  in its entirety. 
         [0048]      FIG. 7  also illustrates an operating state or a situation in which Step D has not been completely concluded, but shows a situation later in time as compared with the situation illustrated in  FIG. 6 . It can be seen in  FIG. 7  that a significant section of the other tool head  14  has already been pushed out of the material block accommodation  20 . This other tool head  14  is pushed into a predetermined position on a manipulator  36  of an industrial robot as it is pushed out, whereby the manipulator  36  is shown only very schematically in  FIG. 7 . 
         [0049]      FIG. 8  illustrates the situation after the other tool head  14  has been pushed out of the material block accommodation  20  according to Step D of the method. The situation that the other tool head  14  is grasped by the manipulator  36  after having been pushed out and moved away from the block holder  18  by means of the manipulator  36  is shown here. 
         [0050]    The shell  24  is pressed out of the material block accommodation  20 , in part, by means of the further movement of the block holder  18  in the opposite direction, according to Step D of the method, by means of the further tool head  28 , in the present case. In  FIG. 8 , the situation that the excess length  30  formed by partially pressing out the shell  24  is separated from a remnant that is only very small (not illustrated in any detail here) of the material, specifically in that the excess length  30  is sheared off by means of the shear blade  34 , is also illustrated. Such a small remnant can be ignored, as such, and fills the space formed by the next tool head  28  only to an insignificant amount, so that the subsequent method sequence is not impaired by it. 
         [0051]      FIG. 9  illustrates the situation that is carried out after replacement of the tool head  28 , for example, or also in between, if a material block  22  was pressed in its entirety, in which situation, after the further tool head  28  or the new tool head  28  has been introduced into the material block accommodation  20 , a further or new material block  22  is placed in front of the further tool head  28 , by means of a block loader  44 , which pivots into a predetermined position for this purpose. 
         [0052]    Although only a few embodiments of the present invention have been shown and described, it is to be understood that many changes and modifications may be made thereunto without departing from the spirit and scope of the invention.