Method and an apparatus for producing multi-level components by shock compression of powdered material

Abstract

The invention refers to a method and an apparatus for producing multi-level components with conform target density from powdered material. The powdered material is filled into a mould die, which includes a multiple of lower and upper relatively movable punches, and the filling height of the column over each punch is associated to the geometrical levels of the final component. The material is optionally pre-compacted by individual static pressure acting on each punch and is compressed by at least one shock or impact device from at least one direction. Compensating adjustments for powder flow between columns and for density gradients are made during the pre-compression and shock compression.

1 . A method for producing stepped or multi-level components from powdered material by filling a moulding die cavity with the material, compressing the material between one, two or more relatively movable lower punches inserted in the same, and at least one or more relatively movable upper punches inserted in the moulding die, characterised in that the compression is performed by means of a shock or impact compression device, emitting kinetic energy from one, two or more directions, with adjustments for density variations and gradients by different means, to form a multi-level material body of higher and homogeneous density.  
     
     
         2 . A method according to  claim 1 , characterised in that a single-level component can be produced between one, two or more lower punches and one, two or more upper punches.  
     
     
         3 . A method according to  claim 1  characterised in that during pre-compaction and/or shock compression, the powder density is compensated for, such that the desired step heights and target density of respective associated steps of the final body produced are reached.  
     
     
         4 . A method according to  claim 1  characterised in that each punch may be subjected to an additional and individually controlled static pressure-applied during the shock compression, enhancing the acceleration displacement of the punch.  
     
     
         5 . A method according to  claim 1  characterised in that a static pressure may be applied prior to and/or retained after the shock compression.  
     
     
         6 . A method according to  claim 1  characterised in that the static pressure on any of the punches may act in a counter-acting direction to the direction of shock compression, braking the punch motion relative to any other punch, so that the braked punch transfers less compression energy to the powder column. Braking may not necessarily be performed by a counter-acting static pressure.  
     
     
         7 . A method according to  claim 1  characterised in that the mass of the punches may be adjusted relatively to each other such that the density compensation may be performed during the shock compression operation.  
     
     
         8 . A method according to  claim 1  characterised in pre-compacting the powder material with a press device, where the individual powder columns between each corresponding lower punch press surface and the corresponding upper punch press surface associated with the steps of the final component, to such a density that each powder column has a column height-density ratio relation to each other, such that during a parallel and equidistant displacement of all the lower punches, and, a counter-acting equidistant and parallel displacement of all upper punches, the final predetermined target density is obtained in each of the associated component steps.  
     
     
         9 . A method according to  claim 1  characterised in that the pre-compaction speed of each of the punches is adapted in such a way, that the punches reach their respective final press position at the same time as before filling level correction of the former press cycle.  
     
     
         10 . A method according to  claim 1  characterised in that the pre-compaction press speed of the punches are adapted in such a way that possible powder flow between the powder columns is compensated for.  
     
     
         11 . A method according to  claim 1  characterised in that the final stage of the pre-compaction is performed with an equidistant motion of all upper punches in a downwards direction and/or an equidistant motion of all lower punches in an upward direction to ensure mechanical contact between all punches and static rams.  
     
     
         12 . A method according to  claim 1  characterised by individually adjusting the filling height of the powder columns above each of the corresponding lower punches, being the distance of the press surface of the lower punches to the moulding die top surface, such that the ratios of the adjusted filling height correspond to the ratios of desired heights and target densities of the respective associated step of the final body produced.  
     
     
         13 . A method according to  claim 1  characterised in that the filling height, of the individual powder columns above the corresponding lower punch press surface, associated with the steps of the final component, are compensated for, by individual relative displacements of the lower punches, possible powder flow between the powder columns and possible powder density gradients that may occur in the powder columns during filling and during compaction.  
     
     
         14 . A method according to  claim 1  characterised in that the press force and punch position of the individual upper and lower punches are measured and compared with desired and predetermined values, and wherein upon detection of a deviation of any of the punches from these values, the filling level is adjusted.  
     
     
         15 . A method according to  claim 1  characterised in that the filling level and the pre-compaction compensations may be performed iteratively over any number of process cycles.  
     
     
         16 . A method according to  claim 1  characterised in that the pre-compacted powder columns are compressed by at least one shock or impact stroke, where a striking unit emits enough kinetic energy to form the body, when striking the material inserted in the moulding die with a striking means, causing higher density of the material, where all lower punches performs a parallel and equidistant displacement relative to all upper punches, which performs a parallel and equidistant, not necessarily of the same distance as for the lower punches, counter-acting displacement, during which the material reaches its target density.  
     
     
         17 . A method according to  claim 1  characterised in that the shock or impact stroke can be performed without pre-compaction.  
     
     
         18 . A machine for producing multi-level components characterised in that it comprises a moulding die with a moulding die cavity, a filling device for filling the moulding die cavity with the powdered material, at least one upper punch and at least one lower punch, with at least one relatively movable to the other (s), and a shock or impact compressing device, from one, two or more directions, that creates kinetic energy through an impact pulse to the material, that generates a material body of higher density.  
     
     
         19 . A machine according to  claim 18  characterised in that a single-level component can be produced.  
     
     
         20 . A machine according to  claim 18  characterised in that it may include a press device that controls each punch individually in a static press motion which may include control from one, two or more directions.  
     
     
         21 . A machine according to  claim 18  characterised in that the static pressure on all individual punches from the press device is retained and may be individually controlled in position and in press force.  
     
     
         22 . A machine according to  claims 18  to  21 ,  claim 18  characterised in that the press device performs the pre-compaction and compensation operations of the powder columns between the upper and lower punches.  
     
     
         23 . A machine according to  claim 18  characterised in that a shock or impact compressing operation may be performed with or without a press device.  
     
     
         24 . A machine according to  claim 18 , characterised in that a system monitors the individual punch positions, a control system operating in response to monitored values, to individually adjust the filling volumes by individual adjustment of the corresponding lower punch positions to a die cavity volume, such that the ratios of the adjusted filling volume correspond to the ratios of the desired heights and densities of the respective associated steps of the final body produced.  
     
     
         25 . A machine according to  claim 18  characterised in that the monitoring system comprises an apparatus for separately monitoring the press force and position of each individual lower punch and for each individual upper punch, and passing the monitored data to the control system, which compares it with correspondingly desired and predetermined values, and wherein the electronic control system is arranged such that, when the monitoring data deviates from the desired values, the filling volume of the individual powder column above each corresponding lower punch, is corrected appropriately.  
     
     
         26 . A machine according to  claim 18 , characterised in that the control system individually adjusts the pre-compaction press speed and acceleration of the upper punches and the lower punches.