Vibration welding of expanded bead polystyrene

Claim 1

A method of making a composite consumable pattern for use in the cavityless type of metal casting, comprising: (a) forming at least two mateable pattern parts, each having at least one mating plane defined by a flat surface except for predetermined melt-down projections on said surfaces, said parts being constituted entirely of a low density expanded closed-cell polymeric material having a density of 3 lbs./ft 3 or less which upon contact with molten metal is ignited and consumed, (b) bringing said parts together into contact with said mating surfaces parallel and juxtaposed, while urging said contact with a force of 5-10 psi, (c) while in said forced contacting relationship, relatively vibrating said parts to promote friction at at least one of the melt-down projections and surfaces thereby promoting a friction weld upon resolidification of the melt-down material, said relative vibration being carried out for a period of time no greater than 2 seconds, with a vibration amplitude of 0.03-0.10" and a frequency of 120-240 cycles/second.

Claim 2

A method of making a composite consumable pattern for use in the cavityless type of metal casting, comprising: (a) forming at least two mateable pattern parts, each having at least one mating plane defined by a flat surface except for predetermined melt-down projections on said surfaces, said parts being constituted entirely of a low density expanded closed-cell polymeric material having a density of 3 lbs./ft 3 or less which upon contact with molten metal is ignited and consumed, (b) bringing said parts together into contact with said mating surfaces parallel and juxtaposed, while urging said contact with a force of 5-10 psi, (c) while in said forced contacting relationship, relatively vibrating said parts to promote friction at at least one of the melt-down projections and surfaces thereby promoting a friction weld upon resolidification of the melt-down material, said relative vibration being carried out for a period of time no greater than 2 seconds, with a vibration amplitude of 0.03-0.10" and a frequency of 120-240 cycles/second.

Claim 10

A method of joining entirely of a low density expanded closed-cell polymeric plastic elements having a density of 3 lbs./ft 3 or less, comprising: (a) forming each said element with a joining surface having a predetermined melt-down thickness, said surfaces being arranged to permit relative movement between the parts when mated for joining in one common direction (b) while urging said joining surfaces together with a force of 5-10 psi measured at said surfaces, reciprocally moving said parts in said direction of freedom relative to each other with a frequency of 120-240 cycles/sec., an amplitude of 0.03-0.10", a cycle time of 2 seconds or less, to produce melting of said predetermined thickness as a result of friction without distortion of the configuration of the elements.

Claim 11

A method of joining entirely of a low density expanded closed-cell polymeric plastic elements having a density of 3 lbs./ft 3 or less, comprising: (a) forming each said element with a joining surface having a predetermined melt-down thickness, said surfaces being arranged to permit relative movement between the parts when mated for joining in one common direction (b) while urging said joining surfaces together with a force of 5-10 psi measured at said surfaces, reciprocally moving said parts in said direction of freedom relative to each other with a frequency of 120-240 cycles/sec., an amplitude of 0.03-0.10", a cycle time of 2 seconds or less, to produce melting of said predetermined thickness as a result of friction without distortion of the configuration of the elements.

Claim 14

A method of making metal castings, comprising: (a) form pattern parts to be joined entirely of expanded closed-cell polymeric thermoplastic material having a density of 3 lbs/ft 3 or less, said parts each being shaped to have one or more joining surfaces effective to mate with complimentary joining surfaces on the other part, said joining surfaces being free to move relative to each other in one common direction when interengaged, (b) while urging said parts together with a force of 5-10 psi measured at the interengaging surfaces reciprocally moving said parts in said direction of freedom relative to each other with a frequency of 120-240 cycles/sec., an amplitude of 0.03-0.10", a cycle time of 2 seconds or less, vibrating at least one of said parts to generate friction to melt a predetermined portion of the part adjacent said interengaging surfaces, which melted stock effects a water-tight bonding film between the parts upon solidification and forms a unitary pattern, (c) coating said unitary pattern with a refractory material, said bonded joint preventing the entrance of any of said refractory material into said joint, (d) inserting said unitary pattern in a casting flask and surrounding said pattern with unbonded dry sand which is vibrated to effect a locked and compacted molding medium about the pattern, and (e) introducing molten metal to said pattern to consume and displace the same for thereby providing a metal replica casting of the pattern; said casting being free of internal defects and being totally sound at the zone where said pattern joint previously existed.

Claim 15

A method of making metal castings, comprising: (a) form pattern parts to be joined entirely of expanded closed-cell polymeric thermoplastic material having a density of 3 lbs/ft 3 or less, said parts each being shaped to have one or more joining surfaces effective to mate with complimentary joining surfaces on the other part, said joining surfaces being free to move relative to each other in one common direction when interengaged, (b) while urging said parts together with a force of 5-10 psi measured at the interengaging surfaces reciprocally moving said parts in said direction of freedom relative to each other with a frequency of 120-240 cycles/sec., an amplitude of 0.03-0.10", a cycle time of 2 seconds or less, vibrating at least one of said parts to generate friction to melt a predetermined portion of the part adjacent said interengaging surfaces, which melted stock effects a water-tight bonding film between the parts upon solidification and forms a unitary pattern, (c) coating said unitary pattern with a refractory material, said bonded joint preventing the entrance of any of said refractory material into said joint, (d) inserting said unitary pattern in a casting flask and surrounding said pattern with unbonded dry sand which is vibrated to effect a locked and compacted molding medium about the pattern, and (e) introducing molten metal to said pattern to consume and displace the same for thereby providing a metal replica casting of the pattern; said casting being free of internal defects and being totally sound at the zone where said pattern joint previously existed.