Extruder die assembly

An extruder die assembly adapted for attachment to the output end of an extruder barrel. The die assembly includes an adapter member and a die head. The adapter member is attached to the extruder barrel, and the die head is pivotally attached to the adapter member by a hinge. The die head can be rotated about the hinge from a first, closed position to a second, open position. First and second clamp plates are slidably attached to the adapter member. The clamp plates are movable from a first, clamping position to a second, unclamped position, and have clamp fingers extending therefrom. The die head has clamp ears extending therefrom in a location such as to lockingly engage the clamp fingers when the die head is in its closed position and the clamp plates are in their clamping position. The clamp fingers and clamp ears are configured to lockingly engage each other by means of tongue and groove joints. A die plate is removably attached to the outer face of said die head by a plurality of bolts passing through slots in the die plate which, when loosened, permits the die plate to be slid into a position wherein the heads of the bolts are aligned with enlarged openings in the slots.

BACKGROUND OF THE INVENTION
 This invention relates to a die assembly used for extruding thermoplastic
 materials.
 In the extrusion of thermoplastic materials, a die head is typically
 attached to the output end of an extruder barrel by bolts. To clean or
 change such die heads, or to remove screws from the extruder barrel, the
 die head must be unbolted from the end of the extruder and all bolts,
 thermocouples, and electrical connections attached to the die head
 disconnected, all of which entails a great deal of labor and down time.
 SUMMARY OF THE INVENTION
 It is an object of this invention to provide a die assembly which is easy
 to clean, does not require disconnection of attachment bolts or electrical
 and thermocouple connections, and allows screws to be removed from the
 extruder barrel without removing the die.
 It is a further object of this invention to provide a die head having a die
 plate that can be removed without removing fasteners.
 The die assembly of the present invention comprises a die head which is
 pivotally attached to the output end of an extruder barrel, the die head
 being locked into place and unlocked by slidable clamping means.

DESCRIPTION OF THE PREFERRED EMBODIMENTS
 In FIG. 1, the end barrel segment body 10 of an extruder is shown. Barrel
 segment body 10 has a first flange 12 on its inner (upstream) end and a
 second flange 14 on its outer (downstream) end. In operation, flange 12
 would be attached to an adjacent (upstream) extruder barrel segment in a
 manner well known in the art, the extruder barrel being typically made up
 of a plurality of such barrel segments similar to barrel segment 10.
 A terminal extruder screw segment 16 is located in a bore 18 centrally and
 longitudinally located in terminal barrel segment body 10. The arrow in
 FIG. 1 indicates the direction of flow of plasticized material through
 barrel segment 10.
 The extruder type with which the die assembly of the present invention may
 be used can be either a single screw extruder or a twin screw extruder,
 both of which types are well known in the art, or with any device which
 supplies molten polymer to a die.
 The die assembly 20 of the invention has an adapter section 22 which is
 attached to the outer flange 14 of barrel segment 10 by bolts (not shown)
 or other suitable attachment means.
 The outer (downstream) face of adapter 22 has a face plate 26 attached
 thereto by any suitable attachments means, such as bolts, welding, etc.
 Alternatively, adapter 22 and plate 26 could be formed as a single piece.
 A transitional cavity 24 is centrally located within adapter section 22 and
 face plate 26. As shown, cavity 24 has an inner (upstream) periphery that
 is coextensive with the outlet periphery of bore 18 of barrel segment 10.
 Face plate 26 of adapter 22 has an upper clamp plate member 30 releasably
 attached thereto by means of four identical locking bolts 32a, 32b, 32c,
 and 32d. As best seen in FIG. 5, locking bolts 32a, 32b, 32c, and 32d pass
 through horizontal slots 34a, 34b, 34c, and 34d, respectively, located in
 upper clamp plate member 30.
 Upper clamp plate member 30 has three clamp fingers 40a, 40b, and 40c
 depending from the bottom 36 thereof, clamp fingers 40a and 40c being
 located at the ends thereof and clamp finger 40b being located in the
 middle thereof. Clamp fingers 40 are preferably formed integral with upper
 clamp plate member 30, but can be formed as separate pieces and welded or
 otherwise attached to the bottom 36 of upper clamp plate member 30.
 A single, enlarged clamp finger 40 is illustrated in FIG. 7. As can be
 seen, clamp fingers 40 have a tongue 42 and a groove 44 extending
 horizontally across the rear thereof.
 Similarly a lower clamp plate member 50 is releasably attached to the face
 26 plate of adapter 22 by means of four locking bolts 52a, 53b, 52c, and
 52d which pass through horizontal slots 54a, 54b, 54c, and 54d,
 respectively, located in lower clamp plate member 50.
 Lower clamp plate member 50 has three clamp fingers 60a, 60b, and 60c
 extending from the top 56 thereof, clamp fingers 60a and 60c being located
 at the ends thereof and clamp finger 60b being located in the middle
 thereof. Clamp fingers 60 are preferably formed as an integral part of
 lower clamp plate member 50, but can be formed as separate pieces and
 welded or otherwise attached to the top 56 of lower clamp plate member 50.
 As can be seen in FIG. 8, lower clamp fingers 60 have a tongue 62 and a
 groove 64 extending horizontally across the rear thereof.
 Pivotal die head 70 (see FIG. 4) is comprised of a transition section 71, a
 die plate 80, and a die tip 82.
 Die head 70 is pivotally attached to adapter section 22 by means of a hinge
 90, and can be rotated about hinge 90 by means of a handle 92.
 Transition section 71 has a die cavity 72 which communicates with the
 cavity 24 of adapter section 22 and, thus, with the bore 18 of extruder
 barrel 10. Die cavity 72 communicates with the exterior of die assembly 70
 via die orifice 84. Die orifice 84 can be a series of holes 84 for
 extruding strands of thermoplastic material, as illustrated in FIGS. 5 and
 6, or a slot (not shown) for extruding a sheet of thermoplastic material.
 As seen by reference to FIGS. 9 and 10, transition section 71 has a
 flattened upper surface or ledge 73 and a flattened lower surface or ledge
 173. Extending upwardly from the rear portion of flattened upper ledge 73
 are three upper clamp ears 74a, 74b, and 74c, as best seen in FIGS. 4 and
 6. As can be seen by reference to FIG. 9, each upper clamp ear 74 has a
 horizontal tongue 75 and groove 76 located in the front face thereof.
 Extending downwardly from the rear portion of flattened lower ledge 173 are
 three lower clamp ears 77a, 77b, and 77c. As can be seen by reference to
 FIG. 10, each lower clamp ear 77 has a horizontal tongue 78 and groove 79
 located in the front face thereof.
 Die plate 80 is attached to transition section 71 by means of four upper
 bolts 86a, 86b, 86c, and 86d, and by four lower bolts 87a, 87b, 87c, and
 87d. See FIGS. 5 and 6. Die plate 80 may be removed from transition
 section 71 by loosening bolts 86 and 87, and sliding die plate 80 to the
 right (as viewed in FIG. 5) so that the enlarged portion of the slots
 through which bolts 86 and 87 pass are aligned with the their heads to
 permit removal of die plate 80.
 The transition section 71 of die head 70 also contains a breaker plate 88
 seated in a suitable recess therein, and a screen pack 89 located in front
 of (upstream of) the breaker plate 88.
 In operation, the die assembly of the invention is attached to flange 14 of
 barrel segment 10 by attaching adapter section 22 thereto by means of
 bolts (not shown) or other suitable attachment means.
 During extrusion, pivotal die head 70 is in the closed and locked position
 shown in FIGS. 1-3 and 5. When it is desired to change screen pack 92 or
 otherwise clean die head 70, upper and lower clamp plate members 30 and 50
 are moved out of locking position by loosening upper locking bolts 32 and
 lower locking bolts 52, respectively, and sliding clamp plate members 30
 and 50 away from bolts 32 and 52. Although the clamp plate members 30 and
 50, as illustrated, would be moved toward the hinge 90 side of the die
 assembly, it is clear that the clamp plate members 30 and 50 could be
 reversed so that they would be slid in the opposite direction to unlock
 die head 70.
 Die head 70 is locked in the closed position by clamp plates 30 and 50 by
 virtue of the mating tongue and groove joints formed between the clamp
 fingers 40 and 60 of upper and lower clamp plate members 30 and 50 and the
 upper and lower clamp ears 74 and 77 of transition section 71, as best
 seen in FIG. 1. Sliding upper and lower clamp plate members 30 and 50 away
 from their locking bolts 32 and 52 slides their upper and lower clamp
 fingers 40 and 60 out of locking engagement with clamp ears 74 and 77 of
 transition section 71, thereby permitting pivotal die head 70 to be opened
 by grasping handle 92 and rotating die head 70 about hinge 90. In its open
 position, shown in FIG. 4, the screen pack 89 can be easily removed for
 cleaning or replacement, and the die head 70 otherwise cleaned.
 Any electrical connections or thermocouple connections to die head 70 would
 be by means of flexible cables typically used for that purpose, but having
 sufficient length that they need not be disconnected when die head 70 is
 rotated to its open position for cleaning.
 If it is desired to replace die plate 80, bolts 86 and 87 are loosened and
 die plate 80 slid horizontally away from them until their heads are
 aligned with the enlarged openings in their respective slots, whereupon
 die plate 80 may be pulled off for replacement.