Method of molding a mechanically frothed urethane resin foam and an open-top injection mold therefore

Claim 3

The method of claim 1 wherein the step of delivering the uncured foam to the runner comprises: preparing a mechanically frothed urethane foam, the foam filling the runner and flowing into the mold cavity as a liquid froth.

Claim 4

The method of claim 1 further comprising: inserting a substrate in the mold cavity prior to the delivery of foam, the foam forming a layer bonded to the substrate upon curing.

Claim 5

The method of claim 1 wherein the mold cavity has a removable insert.

Claim 6

The method of claim 4 wherein said insert is removable with the cured foam and forms part of the molded product.

Claim 7

The method of claim 1 wherein the separated streams of foam rejoin and generally mix in the runner.

Claim 8

The method of claim 6 wherein the step of delivering the uncured foam to the runner comprises: preparing a mechanically frothed urethane foam, the foam filling the runner and flowing into the mold cavity as a liquid froth.

Claim 9

The method of claim 6 further comprising: inserting a substrate in the mold cavity prior to the delivery of foam, the foam forming a layer bonded to the substrate upon curing.

Claim 10

The method of claim 7 further comprising: inserting a substrate in the mold cavity prior to the delivery of foam, the foam forming a layer bonded to the substrate upon curing.

Claim 11

The method of claim 8 wherein the mold cavity has a removable insert.

Claim 12

The method of claim 10 wherein said insert is removable with the cured foam and forms part of the molded product.

Claim 13

The method of claim 11 wherein the step of delivering the uncured foam to the runner comprises: preparing a mechanically frothed urethane foam, the foam filling the runner and flowing into the mold cavity as a liquid froth.

Claim 16

The method as in claim 13 wherein the step of developing a back pressure includes: restricting the flow of liquid froth from the annular runner to the annular cavity of the mold.

Claim 17

The method as in claim 14, wherein the step of delivering the liquid froth to the annular runner includes: delivering the froth through an inlet to the annular runner whereby the froth travels around the annular runner in two flow streams and causing the froth to laterally mix where the flow streams rejoin.

Claim 18

A mold for forming shaped parts, the mold including: a base plate; at least one first shaped part on said base plate; a cover plate adapted to sit on said base plate; at least one second shaped part on said cover plate; said second and first shaped parts cooperating to define a cavity therebetween for forming a shaped part; runner means about the base of said cavity for delivering molding material to said cavity; supply means for delivering at least a first stream of uncured foam molding material to said runner means, said stream separating in said runner means into a pair of oppositely flowing streams; and means for establishing communication between said runner means and said mold cavity along the extent of said runner means, said communication means including a restriction region of reduced cross-sectional area with respect to at least part of said runner means, said region of reduced cross-sectional area imposing a back pressure on foam material in said runner means whereby said runner means will be substantially filled before the foam flows into said mold cavity through said region of reduced cross-sectional area.

Claim 19

A mold for forming shaped parts, the mold including: a base plate; at least one first shaped part on said base plate; a cover plate adapted to sit on said base plate; at least one second shaped part on said cover plate; said second and first shaped parts cooperating to define a cavity therebetween for forming a shaped part; runner means about the base of said cavity for delivering molding material to said cavity; supply means for delivering at least a first stream of uncured foam molding material to said runner means, said stream separating in said runner means into a pair of oppositely flowing streams; and means for establishing communication between said runner means and said mold cavity along the extent of said runner means, said communication means including a restriction region of reduced cross-sectional area with respect to at least part of said runner means, said region of reduced cross-sectional area imposing a back pressure on foam material in said runner means whereby said runner means will be substantially filled before the foam flows into said mold cavity through said region of reduced cross-sectional area.

Claim 20

A mold as in claim 16 wherein: said runner means is tapered from said base plate toward said cavity to form said restriction region.

Claim 21

A mold as in claim 16 wherein: said restriction region includes a restricted passage between said runner means and said cavity.

Claim 22

A mold as in claim 16 wherein: said restriction region includes orifice means between said runner means and said cavity.

Claim 23

A mold structure for forming a molded shape from foam molding material, the mold structure including: a base plate; at least one first shaped part on said base plate; a cover plate adapted to sit on said base plate; at least one second shaped part on said cover plate; said first and second shaped parts cooperating to define therebetween a cavity for forming a shaped part from foam material; runner means communicating with said cavity for delivering foam molding material to said cavity; restriction defining means in said runner means to establish a back pressure in said annular runner means; and supply means for delivering foam molding material to said runner means.

Claim 24

A mold structure for forming a molded shape from foam molding material, the mold structure including: a base plate; at least one first shaped part on said base plate; a cover plate adapted to sit on said base plate; at least one second shaped part on said cover plate; said first and second shaped parts cooperating to define therebetween a cavity for forming a shaped part from foam material; runner means communicating with said cavity for delivering foam molding material to said cavity; restriction defining means in said runner means to establish a back pressure in said annular runner means; and supply means for delivering foam molding material to said runner means.

Claim 25

A mold structure as in claim 20 wherein: said runner means is tapered from said base plate toward said cavity to form said restriction means.

Claim 26

A mold structure as in claim 20 wherein: said restriction defining means includes a restricted passage between said runner means and said cavity.

Claim 27

A mold structure as in claim 20 wherein: said restriction defining means includes orifice means between said runner means and said cavity.

Claim 28

A mold structure as in claim 20 wherein: said cavity is open at the end removed from said runner means.

Claim 29

A mold structure as in claim 20 wherein: said cavity, said runner means and said restriction means are annular; and further including means for positioning a mold insert in said mold structure for forming on said insert an annular shape from foam.

Claim 30

A mold structure as in claim 25 wherein: said mold insert is a belt.

Claim 31

A mold structure as in claim 25 wherein: said mold insert is a roller shaft.

Claim 32

A mold structure for forming an annular molded shape from mechanically frothed foam material, the mold structure including: a base plate; at least one first shaped part on said base plate; a cover plate adapted to sit on said base plate; at least one second shaped part on said cover plate; said first and second shaped parts cooperating to define therebetween an annular cavity for forming a shaped part from mechanically frothed foam material; annular runner means communicating with said cavity for delivering mechanically frothed foam molding material to said annular cavity; annular restriction defining means in said annular runner means to establish a back pressure in said annular runner means; and supply means for delivering mechanically frothed foam molding material to said runner means.

Claim 33

A mold structure for forming an annular molded shape from mechanically frothed foam material, the mold structure including: a base plate; at least one first shaped part on said base plate; a cover plate adapted to sit on said base plate; at least one second shaped part on said cover plate; said first and second shaped parts cooperating to define therebetween an annular cavity for forming a shaped part from mechanically frothed foam material; annular runner means communicating with said cavity for delivering mechanically frothed foam molding material to said annular cavity; annular restriction defining means in said annular runner means to establish a back pressure in said annular runner means; and supply means for delivering mechanically frothed foam molding material to said runner means.

Claim 34

A mold structure as in claim 28 wherein: said annular runner means is tapered from said base plate toward said annular cavity to form said annular restriction means.

Claim 35

A mold structure as in claim 28 wherein: said annular restriction defining means includes a restricted annular passage between said annular runner means and said annular cavity.

Claim 36

A mold structure as in claim 28 wherein: said annular restriction defining means includes annular orifice means between said annular runner means and said annular cavity.

Claim 37

A mold structure as in claim 28 wherein: said annular cavity is open at the end removed from said annular runner means.

Claim 38

A mold structure as in claim 28 including: means for positioning a mold insert in said mold structure for forming therein an annular shape from foam.

Claim 39

A mold structure as in claim 28 wherein: said mold insert is a belt.

Claim 40

A mold structure as in claim 28 wherein: said mold insert is a roller shaft.