Cryogen shot blast deflashing apparatus with inert gas purging system

A cryogen deflashing apparatus comprising:

• (a) tumbling means including a frame structure rotatably supporting a drum-like container defining a treatment chamber for rotation about an axis to impart a tumbling action to contents of the treatment chamber;
• (b) throwing wheel means for receiving a supply of particulate media and for propelling the media into the treatment chamber to impact contents of the treatment chamber while the contents are being tumbled about by rotation of the container during operation of the apparatus;
• (c) cryogen supply means for introducing a flow of cryogen into the treatment chamber for embrittling at least selected portions of the contents of the treatment chamber;
• (d) cryogen recirculation means for withdrawing cryogen gas from the treatment chamber and for redelivering cryogen gas to the treatment chamber through the throwing wheel means during operation of the apparatus;
• (e) media supply means for introducing a metered flow of particulate media into the pressurized flow of cryogen gas which is delivered to the throwing wheel means during operation of the apparatus;
• (f) the receptacle means, the throwing wheel means and the cryogen recirculation means cooperating to define a closed recirculation system;
• and,
• (e) purging means for introducing a plurality of flows of purging gas into the closed recirculation system at a plurality of spaced locations to maintain a positive pressure atmosphere within the closed recirculation system to prevent entry of moisture containing ambient air, and to minimize the condensation of moisture and the formation of ice in the closed recirculation system.

A cryogen shot blast deflashing apparatus, comprising:

• (a) a supporting frame including a pair of upstanding leg structures which are spaced apart one from the other, with each of the leg structures carrying a separate bearing structure near its upper end, and with the bearing structures cooperating to define a first, substantially horizontally-extending pivot axis;
• (b) a receptacle assembly including a rotatable drum, housing means for surrounding at least portions of the rotatable drum and cooperating therewith for defining a closed treatment chamber within which workpieces to be deflashed can be positioned and tumbled about during a deflashing process, the receptacle assembly having a pair of stub shafts extending from opposite sides thereof and being received within the bearing means of the frame structure to support the receptacle assembly for pivotal movement relative to the frame structure about the first pivot axis;
• (c) throwing wheel means carried by the receptacle assembly for introducing a flow of particulate media and cryogen gas into the treatment chamber defined by the rotating drum;
• (d) cryogen recirculation means connected to the receptacle assembly and to the throwing wheel means for withdrawing cryogen gas and particulates from the treatment chamber, for separating reusable particulate media from other withdrawn particulate such as pieces of workpiece flash, and for returning a flow of cryogen gas and particulate media to the throwing wheel for reintroduction into the treatment chamber through a common supply conduit which communicates with the throwing wheel means;
• (e) the receptacle assembly, the throwing wheel means and the cryogen recirculation means cooperating to define a closed recirculation system;
• and,
• (f) purging means for introducing flows of purging gas into the closed recirculation system at a plurality of locations to maintain a positive pressure atmosphere therein to prevent entry of moisture containing ambient air, and to thereby minimize the condensation of moisture and the formation of ice in the closed recirculation system.

A cryogen shot blast deflashing apparatus, comprising:

• (a) an upstanding frame;
• (b) a receptacle assembly supported by the upstanding frame;
• (c) the receptacle assembly including container means which defines a treatment chamber for receiving workpieces, which has an access opening for enabling workpieces to be charged into and discharged from the treatment chamber, and which is mounted for movement relative to the upstanding frame;
• (d) container drive means for moving the container means relative to the frame to impart movement to workpieces which have been charged into the treatment chamber;
• (e) the receptacle assembly additionally including a housing enshrouding at least portions of the container means and having closure means mounted for movement between positions wherein the closure means selectively opens and closes the access opening of the container means;
• (f) throwing wheel means carried by the receptacle assembly for projecting particulate media into the treatment chamber for impacting workpieces contained therein;
• (g) containment means for containing a supply of particulate media;
• (h) cryogen recirculation means including withdrawal conduit means ccnnected to the receptacle assembly for withdrawing cryogen gas from the treatment chamber, supply conduit means connected to the throwing wheel means for delivering cryogen under pressure to the throwing wheel means, and blower means connected to the withdrawal conduit means and to the supply conduit means for evacuating cryogen gas from the treatment chamber through the withdrawal conduit means, for pressurizing such withdrawn cryogen gas, and for delivering such pressurized cryogen gas to the throwing wheel means through the supply conduit means;
• (i) metering means connected to the supply conduit means and to the containment means for introducing a metered flow of particulate media from the containment means into the pressurized flow of cryogen being delivered through the supply conduit means to the throwing wheel means;
• and,
• (j) the receptacle assembly, the throwing wheel means, the containment means and the cryogen recirculation means, and the metering means cooperating to define a closed recirculation system;
• and,
• (k) purging means for introducing a plurality of separate purging flows of gas into the closed recirculation system at a plurality of locations to maintain a positive pressure atmcsphere therein to prevent entry of moisture containing ambient air, and to minimize the condensation of moisture and the formation of ice in the closed recirculation system.

A method of operating a deflashing apparatus to deflash workpieces formed from relatively flexible material, comprising the steps of:

• (a) positioning workpieces to be deflashed in a treatment chamber defined by a receptacle of a deflashing apparatus, and moving the receptacle to impart movement to such workpieces as are positioned within the treatment chamber;
• (b) establishing a flow of cryogen gas and particulate media through the treatment chamber with the cryogen gas being brought into engagement with the workpieces for embrittling workpiece flash, and with the particulate media being caused to impact the workpieces to remove embrittled flash therefrom;
• (c) withdrawing cryogen gas from the treatment chamber, repressurizing the withdrawn cryogen gas, ducting the repressurized cryogen gas into a supply conduit for return to the treatment chamber, and introducing the repressurized cryogen gas into the treatment chamber through a throwing wheel;
• (d) introducing a metered flow of particulate media into the flow of pressurized cryogen gas being ducted through the supply conduit for projection into the treatment chamber through the throwing wheel together with the flow of pressurized cryogen gas;
• and,
• (e) maintaining a positive pressure atmosphere within the closed recirculation system by introducing a plurality of flows of purging gas into the recirculation system to prevent entry into the closed recirculation system of moisture laden ambient air.

A method of deflashing workpieces formed from relatively flexible material, comprising the steps of:

• (a) providing deflashing apparatus which includes
• (i) an upstanding frame;
• (ii) a receptacle supported on the frame and carrying a rotatable container which defines a treatment chamber and has an access opening for charging workpieces into and discharging workpieces from the treatment chamber;
• (iii) closure means for selectively opening and closing the access opening;
• and,
• (iv) throwing wheel means for projecting particulate media into the treatment chamber for impacting workpieces contained in the treatment chamber;
• (b) opening the access opening by moving the closure to an open position;
• (c) charging the treatment chamber with workpieces to be deflashed;
• (d) closing the access opening by moving the closure means to a closed position;
• (e) rotating the container about an axis of rotation to effect a tumbling of such workpieces as have been charged into the treatment chamber;
• (f) supplying a flow of pressurized cryogen and particulate media to the throwing wheel means, and operating the throwing wheel means to project pressurized cryogen and particulate media into the treatment chamber to impact such workpieces as are being tumbled about therein as the container is being rotated;
• (g) withdrawing cryogen gas from the container along a path of flow defined by a withdrawal conduit during the time when the workpieces are being tumbled within the container and are being subjected to a flow of pressurized cryogen and particulate media being projected from the throwing wheel means, ducting the withdrawn cryogen gas along said path of flow to the input of a blower, operating the blower to pressurize the withdrawn cryogen gas, and ducting the pressurized cryogen gas through a supply conduit for return to the throwing wheel means;
• (h) introducing a metered flow of particulate media into the supply conduit from a supply hopper for delivery to the throwing wheel means in combination with the flow of pressurized cryogen being delivered to the throwing wheel means through the supply conduit;
• and,
• (i) during all of the foregoing steps, introducing flows of a purging gas into the supply hopper, and into the withdrawal conduit to maintain positive pressure atmosphere therein.