Patent GB-1172703-A (GB)
Title: Rotary Joint for Extrusion Die.
IPC: B29C48/10
Filed: 1967-01-13
Abstract: 1,172,703. Rotary joint for tubular film extrusion die; rotary extrusion dies. BLACK CLAWSON CO. 13 Jan., 1967 [13 Jan., 1966], No. 2045/67. Headings B5A and B5B. A rotary joint for delivering molten thermoplastic material from a source of such material to the inlet of a rotary die having an annular orifice for the formation of tubular shaped articles such as tubular films by melt extrusion comprises a rotating or oscillating die body 10 (Fig. 1).provided with a central passageway 11 communicating with radially diverging passageways (two of which are shown at 12 and 13) leading to the annular extrusion orifice of the die (not shown). The die body 10 is partially or wholly supported on the rotating joint (illustrated generally at 20) which in turn is supported on a stationary platform 22. The rotary joint comprises an inner joint body 25 fixed to the platform 22 and an outer joint body 26 which rotates with the die body 10 in the inner joint body 25. The outer body 26 is provided with an outer bearing-receiving sleeve 28 which supports a multi-arm die mount 30 having at its lower end an integral annular portion 31 held by screws 34 in the sleeve 28. The mount 30 includes a number of upwardly and outwardly extending support arms 37 the upper ends of which terminate in an integral annular portion 38 in which the die body is held by screws 39. The assembly comprising mount 30, the outer body 26 and the die body 10 is rotated by means of a motor 45 through a chain 43 and a sprocket 40 attached to the underside of sleeve 28 by screws 42. The inner body assembly 25 includes a tubular member 50 of which the upper portion is received within the sleeve 28 and the lower portion 52 is attached to the platform 22 by screws 54. The annular space between the tubular member 50 and the sleeve 28 forms a means for receiving roller bearings 55 and 56 which are provided for the rotation of the outer body assembly 26 about the inner body assembly 25. The bearings are provided with a lower grease seal 60 and an upper grease seal 62 associated with a bearing retaining ring 65 screwed on to the outer surface of the upper end of the tubular member 50. The polymeric material to be extruded is introduced into the melt-extrusion head through a metal tube 70 the lower end of which communicates with a source of the material and the upper end of which extends into the interior of the stationary inner body 25. The upper end 72 of the tube 70 is fixedly mounted within a hollow support bushing 75 and rests against a shoulder 76 therein relatively close to the inlet 11 of the die body 10 and in general alignment with this inlet. The passageway 78 in the bushing 75 forms an extension of the tube 70 and leads to the axial passageway 82 in the seal or bearing 80 consisting of a selflubricating and non-deteriorating compressive material such as a moulded sintered carbongraphite composition having a low modulus of elasticity. The bearing 80 is received within a sleeve-like retainer 85 which is in turn received within a recess in the die body 10 and is retained in place by the annular plate 88 and screws 89. The seal 80 forms a bearing surface 90 with the slightly conical upper surface of the body 75 which is urged into engagement with the member 80 to form a liquid-tight seal or running gland by means of the springs 112 and the annularly spaced support ribs 98.