Abstract:
With the invention, a method and a device for explosive forming of work pieces, in which at least one work piece is arranged in at least one die and there deformed by means of an explosive to be ignited, is to be improved, in that an ignition mechanism that is technically easy to handle is produced with the shortest possible setup times, which permits the most precise possible ignition of the explosive with time-repeatable accuracy. This task is solved by a method and device, in which at least one work piece is arranged in at least one die and deformed there by means of an explosive being ignited, in which the explosive is ignited by means of at least one energy beam.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims priority from German Patent Application Serial No. 102006037742.7 filed on Aug. 11, 2006, entitled “Verfahren and Vorrichtung zum Explosionsumformen” (Method and Device for Explosive Forming), the disclosure of which is incorporated herein by reference for all purposes. 
       FIELD OF THE INVENTION 
       [0002]    The invention concerns a method and a device for explosive forming. 
       BACKGROUND OF THE INVENTION 
       [0003]    During explosive forming, a work piece is arranged in a die and deformed by ignition of an explosive, for example, a gas mixture. The explosive is generally introduced to the die, and also ignited here. Two problems are then posed. On the one hand, the die and the ignition mechanism must be suitable to initiate the explosion in targeted fashion and withstand the high loads occurring during the explosion, and, on the other hand, good forming results with the shortest possible setup times must be repeatedly achieved. 
         [0004]    In a method known from EP 0 830 907 for forming of hollow elements, like cans, the hollow element is inserted into a die and the upper opening of the hollow element closed with a plug. An explosive gas is introduced into the cavity via a line in the plug, which is then ignited via a spark plug arranged in the plug. 
         [0005]    In a method described in U.S. Pat. No. 3,342,048, a work piece being deformed is also arranged in a die and filled with an explosive gas mixture. Ignition occurs here by means of mercury fulminate and a heating wire or filament. Both methods are particularly suitable for individual part manufacture and have not gained acceptance in practice for mass production. 
       SUMMARY OF THE INVENTION 
       [0006]    The underlying task of the invention is to improve a method, as well as device, of the generic type just mentioned, so that an ignition mechanism that is technically simple to handle is produced with short setup times, which permits the most precise possible ignition of the explosive with time-repeatable accuracy. 
         [0007]    This task is solved according to the invention with a method with the features of claim  1 . 
         [0008]    By ignition by means of an energy beam, the explosion can be properly controlled in the die. The energy beam can be positioned relatively precisely at an ignition site, from which the explosion is to proceed. The amount of energy supplied to the explosive by the energy beam is also readily adjustable. In addition, the energy beam, and therefore the explosion, can also be precisely controlled in terms of time. Because of the aforementioned factors, the explosion and its course within the die can be readily controlled. Good predictability and reproduction accuracy of the forming result are thus possible. 
         [0009]    In an advantageous embodiment of the invention, the energy beam can be generated by means of a laser. A laser beam can be well controlled with reference to time and local accuracy. 
         [0010]    Advantageously, the energy beam can be guided from an energy source by means of a deflection device to at least one ignition site. Despite any fixed energy beam generator, the energy beam can be quickly and simply guided to the desired sites in space. 
         [0011]    In one embodiment of the invention, the energy beam can be guided from an energy source by means of a mirror arrangement to at least one ignition site. The mirror arrangement is particularly suitable for energy beams in the form of laser beams and offers the aforementioned advantages of a deflection device. 
         [0012]    In another embodiment of the invention the explosive can be ignited simultaneously at several sites of the device. For example, several detonation fronts can thus be generated within a die. Depending on the site at which the explosive is situated within the die, and the site at which it is ignited, the course of the detonation fronts can then be adjusted to the requirements of the forming process. As an alternative, in this method, explosives can also be ignited in several dies of the device simultaneously. Several even different work pieces can thus be formed almost simultaneously. This helps to shorten the cycle times. 
         [0013]    Advantageously, the explosive can be ignited at several sites of the device with a time offset. If time-offset ignition occurs on an individual die of the device, several detonation fronts can be generated within a die on this account. The time offset then permits adjustment of the time response of the individual detonation fronts within the die. If time-offset ignition occurs on different dies of the device, the energy beam can ignite, for example, all dies of the device in succession. This helps to shorten cycle times, when parallel running forming processes overlap in time. 
         [0014]    In principle, any combinations of simultaneous and time-offset ignition on one and/or several dies of the device are possible. Thus, the process can be well adapted to different production requirements. The basic idea of controlling propagation of detonation fronts via time-variable ignition at one or more sites of the die and thus influencing the forming result would also be attainable independently of the type of ignition, whether it is with an energy beam or otherwise. 
         [0015]    In an advantageous embodiment of the invention, several detonation fronts can be generated within a die. Because of this, and especially because of time control of the course of the detonation fronts, a good forming result can be achieved. 
         [0016]    Advantageously, at least one detonation front each within several dies of the device can be generated. The effectiveness of an ignition device with an energy beam can thus be increased. 
         [0017]    In one embodiment of the invention, the energy beam can be introduced to an ignition tube of the device. Part of the die, namely, the ignition tube, can thus be adjusted to special requirements of the ignition and explosion process. 
         [0018]    In another embodiment of the invention, the energy beam can enter the explosion space through a transparent medium. This can be readily accomplished technically and guarantees good impingement of the energy beam on the explosive. An energy beam generator can thus be positioned outside of the die and largely protected from the direct effects of the explosion in the interior of the die. 
         [0019]    The task is further solved according to the invention by the features of claim  11 . 
         [0020]    The energy beam guarantees good ignition of the explosive. It is technically readily easily generated and can overcome distances quickly. Because of this, the explosive can be ignited with good time accuracy. 
         [0021]    In an advantageous embodiment of the invention, the energy beam generator can include a laser. The laser represents a technically simple possibility for energy beam generation. It offers a readily bundled and therefore readily positionable energy or laser beam with adjustable amount of energy. 
         [0022]    The die can advantageously have at least one introduction site transparent to the energy beam. The energy beam can thus penetrate the die and ignite the explosive contained in it. The energy beam generator can be arranged outside of the die and therefore largely protected from the direct effects of the explosion. 
         [0023]    In one embodiment of the invention, the introduction site can have at least one transparent medium. This is particularly suited for laser beams. It guarantees good transmission of the energy beam with relatively low energy loss. 
         [0024]    The transparent medium can advantageously include a glass insert. Glass is a suitable and easily processed material that offers the aforementioned advantages and is sufficiently resistant to the occurring explosion forces. 
         [0025]    In another embodiment of the invention, the transparent medium can have a thickness in the range from 5 to 15 mm, preferably in the range from 7 to 12 mm, and especially in the range from 9 to 11 mm. This thickness has proven advantageous in practice. It guarantees sufficient stability, in order to withstand requirements by the explosion. 
         [0026]    In an advantageous embodiment of the invention, the transparent medium can have an outside diameter of about 5 to 15 mm, preferably 7 to 12 mm, and especially 9 to 11 mm. It has been found that the outside diameter permits sufficiently good and rapid positioning of the energy beam with simultaneously good stability of the medium. 
         [0027]    The transparent medium can advantageously be lens-like and shaped convex. The energy beam can thus be easily bundled. 
         [0028]    In one embodiment of the invention, the transparent medium can have an approximately square cross-section. This guarantees good stability and good transmission properties. 
         [0029]    The transparent medium can advantageously have an octagonal cross-section. Depending on the shape of the octagon, the energy beam can thus be bundled. 
         [0030]    In another embodiment of the invention, the transparent medium can have a mount containing copper. It has been found that copper alloys, especially copper-beryllium alloys, offer sufficiently good stability and good sealing properties for this application. 
         [0031]    The transparent medium can advantageously be arranged with a seal in the die that seals the explosion space from the surroundings. The surroundings are thus protected from the explosion and the explosion products. 
         [0032]    In one embodiment of the invention, the die can have several introduction sites. The explosive can thus be ignited at several sites of the die simultaneously and/or with a time offset. For example, several detonation fronts can thus be generated in the die. 
         [0033]    In an advantageous embodiment of the invention, several dies can be each provided with at least one introduction site. Because of this, several, optionally also different dies of the device can be ignited simultaneously or with a time offset. If the parallel forming processes overlap in time, the efficiency of the device can be increased. 
         [0034]    At least one deflection device in the beam path of the energy beam generator can advantageously be provided, by means of which the energy beam can be directed toward at least one ignition site. Because of this, the energy beam can be simply, quickly and properly positioned. 
         [0035]    In another embodiment of the invention, the deflection device can be a mirror arrangement. This is particularly suitable for laser beams and offers the aforementioned advantages of a deflection device. 
         [0036]    In a particularly advantageous embodiment of the invention, the deflection device can have at least one mirror element partially transparent to the energy beam. The energy beam can thus be divided into several beams in simple fashion. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0037]    Embodiments of the device according to the invention are described below with reference to the following drawings. In the drawings: 
           [0038]      FIG. 1  shows a device for explosive forming according to a first embodiment of the invention, 
           [0039]      FIG. 2  shows section II-II through the die of the device from  FIG. 1 , 
           [0040]      FIG. 3   a  shows a device according to a second embodiment of the invention, and 
           [0041]      FIG. 3   b  shows a device according to a third embodiment of the invention. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0042]      FIG. 1  shows a device for explosive forming according to a first embodiment of the invention. The device  1  has a die  2  and an energy beam generator  3 . 
         [0043]    The die  2  in this embodiment of the invention is multipart and has a forming device  4  and an ignition tube  5 . In the forming device  4 , a work piece  18 , indicated by a dotted line, is arranged here. In the interior of ignition tube  5 , an ignition chamber  6  is provided. An explosive medium  7  is situated in it. 
         [0044]    An explosive gas mixture, oxyhydrogen gas, is provided as explosive medium  7  in this embodiment, which can be introduced to ignition chamber  6  via connection  8 . In other embodiments of the invention, however, other explosives can also be used in gaseous, liquid or solid form. Connection  8  is then designed according to the explosive as a gas, liquid or solid connection. 
         [0045]    The energy beam generator  3  can optionally generate an energy beam  12  and, in this embodiment, is a laser device, which is mounted on a foot  10  to rotate around its vertical axis  9 . It is supplied with energy via a line  11  and, as required, can generate an energy beam, in this case a laser beam  12 . 
         [0046]    The wall  13  of the ignition tube  5  has an introduction site  14  transparent to energy beam  12 . In the region of introduction site  14 , a transparent medium  15  is provided which is at least partially transparent to the energy beam  12 . In this embodiment of the invention, the transparent medium  15  has a glass insert  19 , which is shown more precisely in  FIG. 2 . 
         [0047]    The laser device  3  is arranged, so that the laser beam  12  can penetrate through transparent medium  15  into ignition chamber  6  of ignition tube  5 . The explosive medium  7  is ignited in an ignition chamber  6  on this account. 
         [0048]    The die  2  of device  1  can optionally also have several introduction sites  14  for the energy beam  12  or ignition sites. The device  1 , as shown with a dashed line here, can have an additional ignition tube  5 ′, for example, which is designed in this embodiment similar to the first ignition tube  5 . Accordingly, it also has an ignition chamber  6 ′ filled with an ignition medium  7 , a transparent medium  15 ′ and a connection  8 ′. 
         [0049]    By rotating the laser device  3  around the vertical axis  9 , the laser device  3  can be brought from its first position  16 , in which the laser beam  12  penetrates the ignition chamber  6  of the first ignition tube  5 , into a second position  17 , in which the laser beam  12  passes through the transparent medium  15 ′ into ignition chamber  6 ′ of the second ignition tube  5 ′, as shown with a dashed line in  FIG. 1 . Thus, the ignition medium  7  in the ignition tubes  5 ,  5 ′, for example, can be ignited in succession by laser device  3 . 
         [0050]    The work piece  18  in this case can be arranged, for example, between the two ignition tubes  5 ,  5 ′, as shown in  FIG. 1  by a dotted and dashed line. 
         [0051]      FIG. 2  shows a section II-II through the introduction site  14  of ignition tube  5  transparent to energy beam  12 . The reference numbers used in  FIG. 2  denote the same parts as in  FIG. 1 , so that the description of  FIG. 1  is referred to in this respect. 
         [0052]    The transparent medium  15  in this embodiment of the invention has a round glass insert  19  with a rectangular cross-section. The outside diameter and thickness of the glass insert are approximately of the same size. In this embodiment, the diameter, as well as the thickness of the glass insert  19 , is 10 mm. 
         [0053]    In other embodiments of the invention, this ratio, however, can vary significantly. The dimensions of the glass insert and its external shape can be adapted to the corresponding application. The cross-section through the glass element, for example, can also be octagonal. In addition, the surface  20  on the ignition chamber side and/or the surface  21  of the glass insert  19  opposite it can be curved, so that an approximately lens-like shape of the glass insert  19  is produced. The material of the insert  19  could also vary, depending on the application. If, as here, a laser is used as energy beam generator, pressure-resistant and heat-resistant, but nonetheless light-transparent plastics are conceivable. 
         [0054]    The transparent medium  15  also has a mount  22 , in which the glass insert  19  is arranged. The mount  22  in this embodiment of the invention is made from a copper-beryllium alloy. This is stable and withstands the dynamically, abruptly occurring, relatively high loads from the explosion. As an alternative, however, the mount  22  can also be made from a different copper alloy or any other material that withstands the high loads from the explosion. Its wall  23  has an L-shaped cross-section. The inside contour of mount  22  then corresponds approximately to the outside dimensions of glass insert  19 . 
         [0055]    The transparent medium  15  is arranged with a seal  24  in ignition tube  5 , which seals the ignition chamber  6  in the interior of ignition tube  5  from the surroundings. The wall  13  of the ignition tube  5  and the mount  22  then form a press-fit. 
         [0056]    Although the design of the device according to the invention is described here with reference to an individual die, the device  1  in other embodiments of the invention can also have several dies  2 , as shown for example in  FIGS. 3   a,    3   b.    
         [0057]      FIGS. 3   a  and  3   b  show possible embodiments of a device according to the invention with several dies. The dies  2   a  to  2   d  then correspond to the die  2  shown and described in  FIG. 1 .  FIGS. 3   a  and  3   b  show merely different possibilities of implementing such a device. The invention is in no way restricted to the embodiments depicted in these figures. Instead, the functional principles depicted in  FIGS. 3   a  and  3   b  can also be combined with each other in any manner, depending on the application. 
         [0058]      FIG. 3   a  shows a schematic view of a device according to a second embodiment of the invention. The reference numbers used in  FIG. 3   a  denote the same parts as in  FIGS. 1 and 2 , so that the description of  FIGS. 1 and 2  is referred to in this respect. The device  1  depicted in  FIG. 3   a  has several dies  2  and several energy beam generators or laser devices  3 . The design of these devices corresponds to the design shown in  FIGS. 1 and 2  and repeatedly occurring same components are therefore provided with the suffix a, b, etc. 
         [0059]    The device  1  here has four dies  2   a  to  2   d  and four laser devices  3   a  to  3   d.  The dies  2   a  to  2   d  are arranged approximately in a circle  30 , indicated here with a dotted line. The laser devices  3   a  to  3   d  are also arranged approximately in a circle  31  that lies approximately concentric within circle  30 . The laser devices  3   a  to  3   d  are arranged in relation to dies  2   a  to  2   d,  so that one of the laser beams  12   a  to  12   d  penetrates through transparent medium  15  into one of the dies  3   a  to  3   d  in ignition chamber  6   a  to  6   d  and can ignite the explosive medium  7  there. 
         [0060]    As an alternative, in the arrangement chosen in  FIG. 3   a,  the two laser devices  3   a  and  3   b  can also be replaced by a single laser device, shown here with a dash-dot line, which is positioned similar to  FIG. 1  rotatable around its vertical axis  9 . By rotation around axis  9 , this laser device could assume both the position of laser device  3   a  and the position of laser device  3   b.  The same applies for laser devices  3   c  and  3   d,  which are similarly also replaceable by a single laser device rotatable around vertical axis  9 . 
         [0061]      FIG. 3   b  shows a schematic view of a device according to a third embodiment of the invention. The reference numbers used in  FIGS. 1 and 2  denote the same parts as in  FIG. 3   b,  so that the description of  FIGS. 1 and 2  is referred to in this respect. The device  1  depicted in  FIG. 3   a  has several dies  2  and energy or laser beam generators  3 . The design of the individual dies  2   a  to  2   d  and of the energy beam generator  3  corresponds to the die  2  and energy beam generator  3  depicted in  FIGS. 1 and 2 . 
         [0062]    The device  1  here additionally has a deflection device  25  for the energy or laser beam  12 . In this case, the deflection device  25  is a mirror arrangement. It has a central polyhedral element  27  and several, in this case three, additional mirror elements  28 . The surfaces of the central element  27  also have mirrors  29 . In this embodiment of the invention, four surfaces of the central element  27  are provided with mirrors  29 . At least of the mirrors  29  can then be partially transparent to the energy or laser beam  12 . Here, three of the mirrors  29  are partially transparent. A partially transparent mirror  29  reflects a predetermined part of the laser light or beam  12  impinging on it. The rest of the laser beam  12  passes almost unaltered through the partially transparent mirror. The laser beam  12  emitted from the laser device  3  can thus be split. 
         [0063]    The central polyhedral element  27  is rotatable around its vertical axis  33 , arranged approximately in the center of a circle  26 , indicated with dotted lines, whereas the mirror elements  28  are arranged approximately on circle  26 . The mirror elements  28  are also mounted to rotate around their corresponding vertical axis  32 . The individual parts  27 ,  28 ,  29  of mirror arrangement  25  are then arranged in relation to the laser device  3  and dies  2   a  to  2   d,  so that the laser beam  12 , according to the alignment of mirrors  28  and  29 , is alternately passed through the transparent medium  15  of one of the dies  2   a  to  2   d  to an ignition site in the corresponding ignition chamber  6   a  to  6   d.    
         [0064]    Although the deflection of mirror arrangement  25  is shown and described here with a central polyhedral element  27  and several mirror elements  28 , the deflection arrangement  25  can be designed in other embodiments of the invention completely differently. The number and position of the mirror elements  28  can vary, depending on the application. The individual elements  27 ,  28 ,  29  of the deflection arrangement  25  need not necessarily be arranged on or within a circle  26 , as shown here. The central element  27 , which is polyhedral here, can also have a different shape, for example, disk-like or be entirely left out. In addition, the individual elements  27 ,  28 ,  29  of the deflection arrangement  25  can also be tiltable relative to each other. For example, the height of the laser beam  12  above the substrate, on which the device stands, can thus be varied. For this purpose, the individual elements  27 ,  28 ,  29  of deflection arrangement  25  can be provided with rotary and/or ball joints. Under practical conditions, other embodiments of the deflection device  25  are also conceivable. The laser beam  12 , for example, can also be guided by means of one or more glass fiber elements to one or more introduction sites  14  in a die  3 . The arrangement and design of the individual dies  2   a  to  2   d  can also deviate from that shown here and vary, depending on the application. 
         [0065]    The method of function of the embodiments depicted in  FIGS. 1 to 3   b  is explained below. 
         [0066]    The method of function is initially described with reference to  FIGS. 1 and 2  for a device with a die and an energy beam generator. The energy beam generator or laser device  3  of device  1  is positioned in  FIG. 1 , so that the laser beam  12  can pass through the transparent medium  15  of wall  13  of ignition tube  5  into ignition chamber  6 . 
         [0067]    The die  2 , in this case the ignition tube  5  of die  2 , is then filled with explosives  7 . For this purpose, an explosive, for example, oxyhydrogen gas, is fed into the ignition chamber  6  of ignition tube  5  via connection  8 . When a predetermined amount of explosive  7  has collected in ignition chamber  5 , the connection  8  is closed. 
         [0068]    To ignite the explosive  7 , an energy beam, in this case a laser beam  12 , is generated in the energy beam generator or laser device  3 . The laser beam  12  emerging from the laser device  3  impinges on transparent medium  15 , passes through it and encounters the explosive  7  in ignition chamber  6 . 
         [0069]      FIG. 2  shows the process more precisely. The laser beam  12  encounters the outer surface  21  of glass insert  19  of transparent medium  15 . Because of the condition and shape of glass insert  19 , the laser beam passes through glass insert  19  largely unhampered and without high deflection and impinges on the surface  19  on the ignition chamber side again from glass insert  19 , and therefore enters the ignition chamber  6  of ignition tube  5 . The laser beam  12  there encounters the explosive  7  and ignites it in the area of ignition site  36 . 
         [0070]    Depending on the shape of glass insert  19 , the laser beam  12  can be varied. With a lens-like glass insert  19  with a curved outer surface  21  and/or curved surface  20  in the ignition chamber side, the laser beam  12  can be bundled, in the case of a convex arch, and thus focused onto a certain ignition site. With a concave arch, the laser beam  12 , on the other hand, can be spread out. If the surfaces  20 ,  21  are sloped relative to each other, as is the case in a polyhedral or octagonal cross-section, the propagation direction of laser beam  12  can be deflected. 
         [0071]    The resulting explosion of explosive  7  develops, within a short time, a relatively large pressure change, which exerts relatively large forces on ignition tube  5  and transparent medium  15 , as well as a relatively large temperature increase. The interface of the transparent medium with ignition tube  5  is also sealed during this abrupt dynamic loading by seal  24 . The interface between glass insert  19  and mount  22  is also sealed by seal  24 . In the first place, this guarantees a good pressure buildup in ignition tube  5 , and, in the second place, protects the surroundings outside of die  2  from the direct effects of the explosion, like pressure and temperature changes, as well as possible harmful explosion products, for example, exhausts. 
         [0072]    The pressure or detonation front forming during the explosion propagates along the ignition tube  5 , enters work piece  18  and forces it into forming device  4 . The detonation front propagates essentially from ignition site  36  spherically. In this case, this means that a part  34  of the detonation front moves in the direction of work piece  18 , starting from ignition site  36 . Another part  35  of the detonation front, on the other hand, moves away from the work piece  18 , as shown in  FIG. 2 . Depending on the design of ignition tube  5  and the position of the introduction  14  and ignition site  36 , the course of the second part  35  of the detonation front can be controlled. 
         [0073]    If the ignition tube  5  is designed so that this part of the detonation front is reflected when it has reached the end of the ignition tube  5 , two detonation fronts  34 ,  35  can be generated, which move over the work piece  18  offset in time. The time offset of the two detonation fronts can be controlled by the position of ignition site  36  and the introduction site  14  and the shape of ignition tube  5 . 
         [0074]    If, on the other hand, the die  2  has several introduction  14  and ignition sites  36 , as indicated with the dashed line in  FIG. 1 , ignition of the explosive  7  can occur at several sites of the die. For this purpose, the laser device  3 , after it has released a first laser beam  12  into ignition chamber  6  of the first ignition tube  5  and has therefore ignited the explosive  7  in the first ignition tube  5 , is rotated around the vertical axis  9  from a first position  16  to its second position  17 . Another laser beam  12  is then generated, which passes through transparent medium  15 ′ of the second ignition tube  5 ′ into the second ignition chamber  6 ′. There, it encounters the explosive  7  and ignites it. Several, in this case two, detonation fronts can thus be generated within one die. 
         [0075]    In addition to time control of the two laser pulses, the course of the two detonation fronts can be influenced, for example, by appropriate arrangement of the introduction  14  or ignition site  36 . In the embodiment of the invention depicted in  FIG. 1 , two detonation fronts are formed, which move one on the other and meet at a certain site in die  2 . 
         [0076]    If several ignition sites in a die  2 , as in  FIG. 1 , or also several dies  2   a  to  2   d,  as in  FIGS. 3   a  and  3   b,  are to be simultaneously ignited, one can alternately work with several laser devices  3  or with only one laser device  3  and a deflection device  25 . The functional principle of these two embodiments of the invention is illustrated in  FIGS. 3   a  and  3   b.  Depending on the application, a combination of both possibilities, i.e., several laser devices  3  and at least one deflection arrangement  25 , also works. 
         [0077]    The arrangement of dies  2   a  to  2   d  and laser devices  3   a  to  3   d  in  FIGS. 3   a  and  3   b  permits both simultaneous and time-offset ignition of the explosive in the individual dies  2   a  to  2   d.    
         [0078]    For simultaneous ignition, in  FIG. 3   a  laser beams  12   a  to  12   d  are simultaneously generated in all four laser devices  3   a  to  3   d,  which approximately simultaneously penetrate through the transparent media  15   a  to  15   d  into ignition chambers  6   a  to  6   d  of the corresponding dies  3   a  to  3   d  and ignite the explosive  7  there. 
         [0079]    In  FIG. 3   b,  on the other hand, only one laser beam  12  is generated, which is divided and deflected via the deflection or mirror arrangement  25 , so that it penetrates approximately simultaneously the transparent media  15   a  to  15   d  into ignition tubes  5   a  to  5   d  of the corresponding dies  2   a  to  2   d  and ignites the explosive  7  there. 
         [0080]    At approximately the same time, at least one detonation front, as already explained with reference to  FIG. 1 , is formed in each of the dies  3   a  to  3   d.    
         [0081]    For time-offset ignition, a laser beam  12   a  to  12   d  is generated in  FIG. 3   a  in the laser devices  3   a  to  3   d  with time offset, for example, in succession. These then enter, in succession, the ignition chamber  6   a  to  6   d  of the corresponding dies  2   a  to  2   d  and ignite the explosive  7   a  to  7   d  in dies  2   a  to  2   d  in succession. Initially, explosive  7   a  in die  2   a,  then explosive  7   b  in die  2   b,  etc., are ignited. The time offset between generation of laser beams  12   a  to  12   d  is then optionally selectable. For example, laser beams  12   a  to  12   d  can be generated simultaneously, whereas laser beams  12   c  and  12   d  can be offset in time. In principle, any combinations are conceivable. 
         [0082]    There are several possibilities in  FIG. 3   b  of igniting the explosive  7  in dies  2   a  to  2   d  with a time offset. In the first place, the laser device  3  can generate several laser beams  12  in succession. Between generation of the individual laser beams, the position of the individual elements  27 ,  28 ,  29  of the deflection arrangement is changed relative to each other and/or the position of laser device  3 , so that the laser beam  12  penetrates, in succession, the transparent medium  15   a  to  15   d  of another die  3   a  to  3   d,  and thus ignites the explosive  7   a  to  7   d.    
         [0083]    As an alternative, the laser device  3  can generate continuous laser beam  12 , which is deflected by means of the deflection arrangement  25  into the ignition chamber  6   a  of the first die  2   a  and ignites the explosive there. If the explosive in die  2   b  is now to be ignited, the position of the individual elements  27 ,  28 ,  29  of the deflection arrangement  25  is changed relative to each other and/or the position of the laser device  3 , so that the laser beam  12  passes through the transparent medium  15   b  into ignition chamber  6   b.  The procedure is similar for ignition of the explosive in dies  2   c  and  2   d.    
         [0084]    If several, for example, two dies are to be ignited simultaneously, partially transparent deflection elements, in this case, partially transparent mirror elements, can be used for energy beam  12 . These permit only part of the laser beam  12  to be deflected, whereas the rest of the laser beam retains its original direction. Thus, the laser beam  12  can be directed toward an ignition site, for example, in die  2   a,  in order to ignite the explosive  7  there. By means of a partially transparent mirror element, part of the laser beam  12  can simultaneously be directed toward an additional ignition site, for example, in die  2   b,  and also ignite the explosive there.