US 3657917 A
Systems for high energy impulse working of materials, compaction, extruding, forging and the like are disclosed in which a piston mass is accelerated toward a dual-piston hammer assembly including a pair of pistons separated by a pressurized liquid to form an effectively rigidized assembly for transmitting the high energy impulses while applying a pre-compression to the material to be worked. To make a densely compacted high quality precision manufactured article from powdered material such as metallic particles or particles of the refractory type, the surfaces of the particles are chemically cleaned, and then the particles are maintained under a clean, chemically inert atmosphere, being introduced into the die cavity which is then evacuated of gas, and the particles are pre-pressurized by the dual-piston hammer assembly. The piston mass is impacted at high velocity to apply a high energy impulse through a ram die to strongly bond the particles together under a hard vacuum, making an article precisely conforming to the die configuration. Transfer molding of material is accomplished by pre-pressurizing the material by means of the dual-piston hammer assembly and thereafter impacting the piston mass to apply a high energy impulse through a ram die to drive and transfer mold the pre-pressurized material into the die cavity. Forging is similarly accomplished by using the dual-piston hammer assembly to pre-pressurize the material between the forging dies and thereafter impacting the piston mass to apply a high energy impulse to forge the material between the dies. A controlled amount of inert atmosphere or a vacuum is provided about the material to be worked which is hermetically sealed within the die chamber.
Description (OCR text may contain errors)
United States Patent Chelminski  SYSTEMS FOR HIGH ENERGY IMPULSE WORKING OF MATERIALS, COMPACTION, E XTRUDING, F ORGING AND THE LIKE Stephen V. Chelminski, West Redding, Conn.
 Assignee: Bolt Associates, Inc., Norwalk, Conn.
 Filed: Feb. 24, 1970  Appl. No.: 13,709
3,468,152 9/1969 Croseck et a1.
3,352,143 11/1967 Bollar 72/453 X 3,376,723 4/1968 Chelminski... ..72/56 2,855,628 10/1958 Lassman 18/165 X 3,187,548 6/1965 Murek 72/453 X Primary Examiner-Charles W. Lanham Assistant Examiner-Donald M Gurley Attorney-Robertson, Bryan, Parmelee & Johnson  ABSTRACT Systems for high energy impulse working of materials, compaction, extruding, forging and the like are disclosed in which a piston mass is accelerated toward a dual-piston hammer assembly including a pair of pistons separated by a pressurized liquid to form an effectively rigidized assembly for transmitting the high energy impulses while applying a pre-compression to the material to be worked. To make a densely compacted high quality precision manufactured article from powdered material such as metallic particles or particles of the refractory type, the surfaces of the particles are chemically cleaned, and then the particles are maintained under a clean, chemically inert atmosphere, being introduced into the die cavity which is then evacuated of gas, and the particles are pre-pressurized by the duaLpiston hammer assembly. The piston mass is impacted at high velocity to apply a high energy impulse through a ram die to strongly bond the particles together under a hard vacuum, making an article precisely conforming to the die configuration. Transfer molding of material is accomplished by pre-pressurizing the material by means of the dual-piston hammer assembly and thereafter impacting the piston mass to apply a high energy impulse through a ram die to drive and transfer mold the pre-pressurized material into the die cavity. Forging is similarly accomplished by using the dual-piston hammer assembly to prepressurize the material between the forging dies and thereafter impacting the piston mass to apply a high energy impulse to forge the material between the dies. A controlled amount of inert atmosphere or a vacuum is provided about the material to be worked which is hermetically sealed within the die chamber.
5 Claims, 4 Drawing Figures PKTENTEU APR 2 5 m2 SHEET 20F 2 INVENTQR. I Step/1e K azelmmsm BY SYSTEMS FOR HIGH, ENERGY IMPULSE WORKING OF MATERIALS; COMPACTION. EXTRUDI-NG, FORGING 1 AND THE LIKE This invention relates to a method and system for working materials with high'energy impulses. More specifically, this invention relates to a method andsystenr for high energy impulse. compression of powered material into structurally high quality articles and high energy forming and forging of materialsinto dies.
In U.S. Pat. No. 3,376,723 is disclosed methods and'apparatus for forming material by sudden impulses. As described in the patent a free moving piston mass is accelerated towards a second'piston by means of the abrupt release of a confined high pressure gas. The second piston is spaced from the material to be formed by pressurized liquid adjacent to the material so that the impulse produced by the impact of the accelerated mass upon the second piston produces high pressure shockwave in the. liquid'to drive the. material into a shape determined by a die cavity.
In the high energy impulse material working method and ap paratus in accordance with the present invention an accelerated pistonmass is impacted upon a dual-piston hammer assembly formed of a pair of pistons separated by a pressurized liquid to form an effectively rigid efficient transmitter of impulses to the material to be worked.
An advantage of the apparatus. in accordance with the present invention resides in the direct contact of a die attached to one of thedual pistons with the material to be worked. A mechanical amplification of the'high energy impulse is obtainable by selectively shaping the portion of the piston in contact with the material.
A significant aspect of this invention resides in the method and apparatus for high energy compression of powdered material in avacuurn to make structurally high quality articles.
A powderedmaterial such as powdered metal or powdered material of the refractory type is placed in adie cavity, and a v die attached to one of the pistons of the dual-piston hammer assembly in-accordance with the inventionis brought into operativecompression contact with the powder. The liquid.-
located between the two pistons in thedual-piston hammer assemblyis then pressurizedto both effectively rigidize the dualpiston and toprecompress the powderedmaterial; A piston mass is thenacceleratedalong a cylinder to impact uponthe dual-piston. hammer assembly and thereby high energy impulse compressthe powder betweenthe dies so thatits parti cles bond together to form a high quality structural article.
Very high energy impulses are obtainable and ofnsufficient' material with high energy impulses for example for working a powdered material with high energy impulses, and schematically illustrating the various controls associated with the system;
FIG. 2 is a section view in elevationof the dual-piston hammer assembly used with the method and system such as depicted in FIG. 1, for the purpose of working powdered material with highenergy impulses;
FIG. 3 is a sectional view in elevation of the dual-piston hammer assembly used with the method and system such as depicted in FIG. 1, for the purpose of material working by transfer molding into a die; and
FIG. 4 is a section view in elevation of a portion of the dualpiston hammer assembly used with the method and system such as depicted in FIG. I, for the purpose of forging a materia1 With reference to FIG. 1, a high energy impulse material 'working method and system are shown including a high pressure heavy duty press, generally indicated at 12 for bolding a die member 14 and an impulse generator 16 aligned with a dual-piston hammer assembly, generally indicated at 18 having a die member 19 (FIG. 2) in contact with powdered material 20 located in a cavity 22 of the die member 14.
magnitude to strongly bond the powdered particles together into a high quality manufactured part preciselyconforming to the die configuration.
A particular advantage of the method and system of this invention resides in thevacuum forming of powdered materials into' structurally high quality and precisely dimensioned products. The die cavity after powder insertion is evacuated, preferably to a hard vacuum, and then the powder is high energy impulsecompressed by an accelerated piston mass inipactedupon a dual-pistonhammer havinga die in contact with the powder. This high energy vacuum forming of powdered materials preserves their purity and improves the quality control of the finalarticle, causing the particles to cohere together to form a dense homogeneous part.
Another advantage of the present-invention is that it enables strong precision parts to be made at high energy forming rates underprecisely controllable conditions of (a) pre-pressurization, (b) ultimate pressure applied and (c) rate of formation of the material being formed. I
Other aspects, objects and advantages of the high energy impulse material workingmethod and system of this invention will be more fully understood from the following descriptionof a method and system in accordance with the invention when considered in conjunction with the. accompanying drawings wherein:
FIG. 1 is a section view in elevation illustrating the method and system embodying the present invention for working The dual-piston hammer assembly l8 is located in the bore 24 of its hammer cylinder 25 and is formed of an impact receiving piston 26, a column 28 of pressurized hydraulic liquid and a die-carrying piston 30. The die-carrying piston 30, in the embodiment shown, is provided with a compression die member 19 of smaller cross-sectional area than the main body of the piston 30 for impulse amplification. The compression die'member 19 is in the shape of a rod ram and is connected to the piston 30 by screwing into a socket 32 and projects from the lower surface 34 of the piston 30 and is sized so as to define a die chamber 36 between the lower surface 34 and the die member 14 when the die 19 operatively contacts the powdered material 20.
The chamber 36 is evacuable by means of a high vacuum pump 37 (FIG. 1) operatively connected to the chamber 36 through a conduit 38 and a passage 40 in the female die member 14. The passage 40 and the conduit 38 are of a sufficient size to draw a high vacuum within the chamber 36 which communicates with the die cavity 22 through the clearance space 42 between the compression ram 19 and the female die member 14. The pressure in the cylinder 25 is in sealing relationship with die"l4 by means of suitably located seals 44 so thatja clean powder-working environment can be provided in.
the die cavity 22 in the form of a'hard vacuum, if desired.
The hydraulic liquid column 28 is pressurized through a passage 47 and through a solenoid operated valve 49 by a hydraulic pressure control and liquid reservoir 45. The liquid column 28 may be depressurized to allow the piston 26 to 'drop. The liquid column 28 has sufficient vertical height to provide the desired amount of pre-pressurization of the pow- .de red material 20. The greater the pressure applied by the supply 45 to the liquid 28, the greater the compaction of the powdered material 20, and the larger the vertical spacing between the dual pistons 30 and 26 During operation of the high energy impulse generator 10, the liquid column 28 is sufficiently pressurized to force the um die 19 down against the powdered material 20 for prepressurization thereof while driving the piston 26 up against an annular stop shoulder 46. The piston 26 is provided with an impact receiving surface 48 facing upwardly into a bore 50 of an acceleration cylinder 52 to receive an accelerated piston mass 54 shown poised at the other end of the bore 50. The surface 48 is protected with a thin layer 55 of vacuum oil or the like to prevent damage to the piston mass 54 and piston 26.
In view of the high pressurization of the liquid column 28,
the highvacuum in the die chamber 36 and the operative The impulse generator 16 includes apparatus 60 for abruptly releasing high pressure gas, which is sometimes referred to as an airgun 60. Airgun 60 releases high pressure gas in an abrupt manner through its discharge ports 62 communicating with a chamber 64 extending above the piston mass 54. The high pressure gas is obtained from a high pressure source 66. This high pressure source 66 may comprise a high pressure air compressor, a receiver tank, and a pressure regulator and filter. The source 66 is connected through a supply line 67 to the airgun 60. This airgun 60 is an apparatus for suddenly releasing high pressure gas with explosive-like abruptness, such as described in detail in connection with Figure 15 of U.S. Pat. No. 3,379,273. A gas release signal from an electrical controller 68 is applied through an electric cable 69 to a solenoid operated valve 70 which actuates the abrupt release of powerful gas pressure from the airgun 60 through its discharge ports 62.
The chamber 64 is shaped with as small a volume as possible and is filled with a liquid such as light oil so that pressurization of the chamber 64 by airgun 60 may be obtained with a substantial preservation of the pressure therein to accelerate the piston mass 54 along the bore 50 towards the dual-piston hammer assembly 18.
The piston mass 54 is of substantial weight and is initially held at the end of the bore 50 by use of hydraulically loaded roller cam follower locking retainers 72 which engage a grooved detent 71 in a piston retainer rod'73 having a tapered shank 70 on the piston mass 54. Retainer pistons 72 are slidably mounted in hydraulic cylinder guides 74 and are hydraulically biased towards the piston retainer rod 73 by means of a spring-loaded hydraulic accumulator 75 connected through hydraulic lines 76, 77, and 78. The hydraulically loaded cam follower locking retainers 72 are released by a solenoid operated valve 79 as controlled by the controller 68 through an electric cable 81.
A gas discharge port 80 from the chamber 64 is connected through suitable tubing 83 to a solenoid-controlled discharge valve 82 and to a solenoid-controlled storage valve 84. The valve 82 permits the escape of gas from the chamber 64 to ambient through a separator 84 for separating the gas from the oil used to fill the volume of chamber 64 so that the oil is returned to the chamber 64 through tubing 85, and the gas is vented to atmosphere through an outlet 86. The valve 84 controls the flow of gas to a storage tank 88 capable of being pressurized to the gas pressure level present in chamber 64 after the piston mass 54 has impacted on'the dual-piston hammer assembly 18.
A solenoid controlled valve 90 is interposed in a conduit 92 which interconnects the gas in the storage tank 88 with the underside of the piston mass 54 when the latter has come to rest upon the dual-piston hammer assembly 18.
A cylinder bore evacuator pump 94 is operatively connected through a solenoid controlled valve 96 and a conduit 98 to the bore 50. This pump 94 evacuates the bore 50 to a very low pressure level that enables the kinetic energy of the accelerated piston mass 54 to be substantially dissipated when impacting on the surface 48 of the upper piston 26 of the dualpiston assembly 18.
The electric controller 68 is provided with the timing circuits and switches to properly sequentially energize the several solenoid-operated valves and the relays (not shown) which control the pumps and to control the firing of the airgun 60.
In the operation of the high energy impulse material working system the piston mass 54 is located in the poised position as shown and the accelerating bore 50 is evacuated by the pump 94.
A powder material to be worked is initially chemically cleaned and is then maintained under a clean chemically inert atmosphere such as helium or nitrogen so that its individual particles have thoroughly cleaned surfaces capable of being coalesced and cold welded together under compression by the system 10.
The large piston 13 and platen 11 of the heavy duty press 12 are lowered along the vertical guide posts 99 of the press 12 to reveal the die cavity 22, and a measured quantity of the clean powdered material is placed in the cavity 22 while maintaining it under an inert atmosphere. The press is then actuated to raise the die 14 to meet the seals 44 of the hammer cylinder 25 and to firmly hemetically seal the chamber 36.
The high vacuum pump 37 is then actuated and quickly reduces the pressure in the chamber 36 to the desired very low pressure operating range. Simultaneously the die cavity 22 is evacuated and shortly thereafter the fluid column 28 is pressurized, whereby the piston 26 is pressed against the annular stop surface 46 and the ram die 19 compresses the powder 20. This pre-compression of the powder 20 is carried out until the optimum pre-compression is reached as previously determined for the particular type of powdered material 20 being worked. When the desired pre-compression is reached, it is held. At this time the dual-piston hammer assembly 18 has been also effectively fully rigidized to be prepared for trans mission of a high energy impulse from the piston mass 54 to the powdered material 20. The top platen 100 of the press 12 is secured to the guide posts 99 by means of large screw threaded collars 101 which hold a series of removable positioning sleeves 102 serving to hold the platen 100 down against locking rings 103.
The airgun 60 is now actuated and abruptly emits a high pressure supply of gas for example, in the range from 1,000 pounds per square inch to 10,000 pounds per square inch, into the chamber 64 just after the retainers 72 have released their grip on the retainer rod 73 of the piston mass 54.
The piston mass 54 is now propelled towards the dual-piston hammer assembly 18 under the powerful force exerted by the pressurized gas in chamber 64. This piston mass 54 attains a high velocity and is impacted upon the layer 55 of protective high impact resistant oil on the surface 48 of the piston 26. The impact of the piston mass 54 releases a huge high energy impulse on the hammer assembly 18 which transmits this impulse to the ram die 19. The ram die 19 thereupon compacts the powdered material 20 to such an extent and in such short time period that the powder particles bond together to form a densely compacted precisely shaped part.
At this time the piston mass 54 has come to rest upon upon the surface 48 and the amount of pressure in the chamber 64 and in the portion of the bore 50 above the piston mass 54 remains at a substantial value. The valve 84 is opened and the tank 88 becomes pressurized by the gas in the chamber 64 in the bore 50. The valve 84 is thereupon closed, and the valves 82 and 90 are then opened. The pressure in the liquid column 28 is lowered to drop piston 26 sufficiently to allow the gas from conduit 92 to raise piston mass 54 back to its initial set position as shown. As the piston mass 54 is being raised up to its initial set position, the excess gas in the chamber 64 is vented out through the port 80 and through the line 83 and through valve 82 and finally out to atmosphere through the oil-gas separator 84 and its outlet vent.
The large piston 13 and platen 11 of press 12 are now lowered to lower the die 14 to enable removal of the formed article from the die cavity 22. A push rod 97 is used to remove the formed article from the die.
A new supply of powdered material is then inserted in the die cavity 22 and another article may be formed in the method described.
In FIG. 3 is shown a portion of a high energy impulse material working system similar to that shown in FIG. 1, except that is is adapted for transfer molding of a precut block of material into a die cavity 122 in a female die 114. In the operation of this apparatus an inert atmosphere is introduced through the conduit 38 and passage 40 so as to flush out any traces of the atmosphere in the die chamber 36 and in the die cavity 122. The fluid column 28 is preferably pre-pressurized to a pressure level just below that required for a flow of the hot or cold material 120 into the die cavity 122. Impact of the piston mass 54 (See FIG. 1) on the dual-piston hammer asunderside of the material 130 is also forged into a shape determined by a cavity 136 in a die 138 resting upon the lower platen 11 of the heavy duty press 12.
If desired, the die chamber 36 can be evacuated through the passage 40 and conduit 38 or alternatively an insert atmosphere can be introduced into this die chamber. The seals 44 provide a hermetic seal for the chamber 36 when the press 12 is holding the die 14, 114 or 138 up against the seals 44 which are located in the lower rim of the hammer cylinder 25.
1. In a system for forming a material with the application of a sudden high-energy impulse from an accelerated piston mass travelling along a path in a cylinder and with a hammer toward which the piston mass is impacted, the invention comprising: a
dual-piston hammer formed of'a first free-moving piston located to receive the impact force of the accelerated piston mass, said dual-piston hammer further including a second free-moving piston positioned on the opposite side of said first free-moving piston from the path of travel of said piston mass, said second free-moving piston having means for connection to a die having operative contact with thematerial who worked and a rigid second cylinder surrounding both said first and second free-moving pistons, said second free-moving piston normally being spaced from said first free-moving piston in said second cylinder, pressurized liquid supply means connected to said second cylinder for introducing substantially incompressible pressurized liquid into said second cylinder between said first and second free moving pistons to form a rigid impulse transmitting hammer capable of pre-pressurizing the material to be worked.
2. In a system for forming material with the application of a sudden high-energy impulse from an accelerated piston mass, the invention as claimed in claim 1, wherein a ram die member is held by said connection means, a second die having a die cavity therein for receiving the material to be worked, said ram die member extending into said die cavity and having a die area substantially smaller than the area of said second piston acted upon by the pressurized liquid in said second cylinder for increased material working pressures to be imparted by the ram die member to the material to be worked.
3. In a system for forming material with the application of sudden high-energy impulses from an accelerated piston mass, the invention as claimed in claim 2, wherein said second cylinder defines a region surrounding said ram die and said die cavity, sealing means are provided for sealing said region, and pump means are provided for evacuating said region.
4. In a system for working material by the application of a sudden high-energy impulse from an accelerated piston mass travelling in a cylinder andwith a hammer toward which the piston mass is impacted, the invention comprising: a dualpiston hammer formed of a first free-moving piston positioned toreceive the impact force from said accelerated piston mass, a rigid hammer cylinder surrounding said first free-moving piston, a second free-moving piston positioned in said hammer cylinder on the opposite side of said first free-moving piston from said piston mass, said dual-piston hammer including means for introducing liquid into said hammer cylinder between said first and second free-moving pistons and for pressurizing said liquid, stop means engageable by said first free-moving piston to retain said first piston against the force exerted thereon by said pressurized liquid, a die carried by said second piston, and a second die positioned in opposed relationship to said first die, said first and second dies defining a die cavity between them in which material is placed to be worked.
5. In a system for forming material with the application of a sudden high-energy impulse from an accelerated piston mass travelling in a cylinder toward a hammer upon which the impact force of the piston mass is applied, the invention comprising: a dual-piston hammer structure including a first and second piston mounted in a rigid hammer cylinder, means for introducing pressurized liquid into said hammer cylinder between said pistons, means for connecting a die to said second piston, and said piston mass having a retainer rod extending therefrom in the direction away from said dual-piston hammer structure, and releasable retainer means engageable with said retainer rod for holding said piston mass in its initial position in the cylinder.