Low energy recovery compounding and fabricating apparatus for plastic materials

Claim 2

A gear pump for pumping highly viscous media comprising: housing means defining an inlet passage at one end, an outlet passage at an opposite end and a chamber therebetween; a pair of pump gears generally horizontally positioned within said chamber having intermeshing teeth and being rotatably mounted in said housing, said chamber and said pump gears defining therebetween a media free space; said chamber and each of said gears defining gear sealing zones adjacent said outlet passage, each sealing zone having a minimum length equal to the circumferential distance between two adjacent gear teeth across the full axial length of the gears at the outside diameter of said gears; said media free space expanding from the end of said seal zones remote from said outlet passage such that an increasing hydraulic radius is produced at least to the plane of the tops of said gears, said increasing hydraulic radius being produced by an increasing horizontal dimension of the chamber from the end of said seal zones remote from said outlet passage to the plane of the tops of said gears, whereby a pressure gradient is created to fill the gear cavities with said viscous media; said outlet passage adjacent said sealing zones having a cross-sectional area of from 0.2 to 2.0 times the product of the gear width and the gear tooth height; and said chamber increasing in cross-sectional area above the tops of said gears to the top of said chamber, thereby enhancing the pumping capacity and volumetric efficiency of said gear pump.

Claim 3

The pump in accordance with claim 1 wherein said outlet is generally rectangular in shape having a width equal to the gear face width and a length equal to the gear tooth height with the major dimension being parallel to the gear axis.

Claim 4

The pump of claim 1, wherein the ratio of media free space clearance to the circumferential distance from said seal zone is in the range of about 0.2 to 0.9.

Claim 5

The pump of claim 1, wherein said media free space is defined by the interior surface of said housing such that the free space increases in cross section from said seal zone in a smooth continuous curve, to a location upstream of said gears.

Claim 6

The pump of claim 1, wherein said housing comprises a pair of modular housing portions defining said media free space at their interior surfaces and symmetrical about the mesh line of said gears; a pair of end structure modules abutting the axial ends of said housing portions and rotatably mounting said gears, said end structures extending beyond said housing portions; and a modular outlet structure nested with the outlet of said housing portions between said end structures, and means interconnecting said modules.

Claim 7

The pump of claim 1, further including means in said housing means for introducing an additive to said viscous media.

Claim 8

The pump of claim 6, wherein said introducing means includes an extruder having its outlet positioned adjacent said free space and its inlet exterior of said housing.

Claim 9

The pump of claim 7, wherein said housing means defines a feedback chamber extending from said pump outlet to a point upstream of said extruder outlet, whereby polymer may be initially mixed with the additive in said extruder.

Claim 10

The pump of claim 8, wherein introducing means is positioned to introduce the additive at a location upstream of said chamber.

Claim 11

The pump of claim 1, further including a pair of feed rollers rotatably mounted upstream of said pair of gears, the axis of each roller being substantially parallel to the axis of the associated gear, and said rollers being spaced apart to define a media nip substantially coplanar with the mesh line of said gears; said housing means including wiper means adjacent each roller; and means for rotating said rollers to draw said media into and feed said gears.

Claim 12

The pump of claim 10, wherein said means for rotating said rollers includes a gear train operatively coupling each roller to its associated gear, whereby the rollers are driven conjointly with said gears.

Claim 13

The pump of claim 10, wherein said means for rotating said rollers includes a drive means operatively coupled to said rollers, whereby said rollers are driven independently of said gears.

Claim 14

The pump of claim 10, wherein said rollers are modular in construction, whereby the axial length thereof may be varied.

Claim 15

The pump of claim 1, wherein said housing is modular and includes two interconnected portions.

Claim 16

The pump of claim 14, wherein said housing modular portions are symmetrical about the mesh line of the gears.

Claim 17

The pump of claim 14, wherein said housing modular portions are symmetrical about the plane extending transversely to said gear axes.

Claim 18

The pump of claim 16, further including modular housing insert means interposed between and complementary to said modular portions.

Claim 19

The pump of claim 14, wherein said housing includes removable central insert means, said insert means defining said media free space at their inner surface.

Claim 20

The pump of claim 18, wherein said insert means extends the full axial dimension of said gear face width.

Claim 21

A gear pump for pumping highly viscous media provided to the pump in rope-like strand form comprising: housing means defining an inlet passage at one end, an outlet passage at an opposite end and a chamber therebetween; a pair of pump gears located within said chamber having intermeshing teeth and being rotatably mounted in said housing, said chamber and said pump gears defining a media free space; said chamber and each of said gears defining gear sealing zones adjacent said outlet passage, each sealing zone having a minimum length equal to the circumferential distance between two adjacent gear teeth across the full axial length of the gears at the outside diameter of said gears; said media free space expanding from the end of said seal zones remote from said outlet passage such that an increasing hydraulic radius is produced at least to the plane of the tops of said gears, said increasing hydraulic radius being produced by a dimension of the chamber measured in a plane parallel to the plane passing through the axes of said gears, said dimension increasing from the end of said seal zones remote from said outlet passage to the plane of the tops of said gears, whereby a pressure gradient is created to fill the gear cavities with said viscous media; said outlet passage adjacent said sealing zones having a cross-sectional area of from 0.2 to 2.0 times the product of the gear width and the gear tooth height; said chamber increasing in cross-sectional area above the tops of said gears to the top of said chamber, thereby enhancing the pumping capacity and volumetric efficiency of said gear pump; and a pair of feed rollers rotatably mounted in said chamber upstream of said gears, the axis of each roller being substantially parallel to the axis of the associated gear and said rollers being spaced apart to define a media nip substantially coplanar with the mesh line of said gears, and means for rotating said gears and rollers, whereby said rope strand is drawn into and feeds the gear cavities and thereafter pumped by said gears.

Claim 22

A gear pump for pumping highly viscous media provided to the pump in rope-like strand form comprising: housing means defining an inlet passage at one end, an outlet passage at an opposite end and a chamber therebetween; a pair of pump gears located within said chamber having intermeshing teeth and being rotatably mounted in said housing, said chamber and said pump gears defining a media free space; said chamber and each of said gears defining gear sealing zones adjacent said outlet passage, each sealing zone having a minimum length equal to the circumferential distance between two adjacent gear teeth across the full axial length of the gears at the outside diameter of said gears; said media free space expanding from the end of said seal zones remote from said outlet passage such that an increasing hydraulic radius is produced at least to the plane of the tops of said gears, said increasing hydraulic radius being produced by a dimension of the chamber measured in a plane parallel to the plane passing through the axes of said gears, said dimension increasing from the end of said seal zones remote from said outlet passage to the plane of the tops of said gears, whereby a pressure gradient is created to fill the gear cavities with said viscous media; said outlet passage adjacent said sealing zones having a cross-sectional area of from 0.2 to 2.0 times the product of the gear width and the gear tooth height; said chamber increasing in cross-sectional area above the tops of said gears to the top of said chamber, thereby enhancing the pumping capacity and volumetric efficiency of said gear pump; and a pair of feed rollers rotatably mounted in said chamber upstream of said gears, the axis of each roller being substantially parallel to the axis of the associated gear and said rollers being spaced apart to define a media nip substantially coplanar with the mesh line of said gears, and means for rotating said gears and rollers, whereby said rope strand is drawn into and feeds the gear cavities and thereafter pumped by said gears.

Claim 23

The pump in accordance with claim 20, wherein said outlet is generally rectangular in shape having a width equal to the gear face width and a length equal to the gear tooth height with the major dimension being parallel to the gear axis.

Claim 24

The pump of claim 20, wherein the ratio of media free space clearance to the circumferential distance from said seal zone is in the range of about 0.2 to 0.9.

Claim 25

The pump of claim 20, wherein said means for rotating said rollers includes a gear train operatively coupling each roller to its associated gear, whereby the rollers are driven conjointly with said gears.

Claim 26

The pump of claim 20, wherein wiper means are provided adjacent each of said rollers.