Neck ring/plunger assembly for a glassware forming machine

Abstract: A neckring plunger assembly for forming parisons in a glassware forming machine comprises a neck ring (56) and a guide ring (58) which defines part of the mould cavity for the neck portion of the parison. The guide ring (58) is urged into engagement with the neck ring (56) by spring means (30) of the plunger mechanism even when wear of the guide ring (58) occurs. Flanged finishes of the parison are thereby avoided.

Description: The present invention relates to individual section glassware forming machines which form containers in the press and blow process, and more particularly, to the neck ring/plunger assembly of such machines which together form the neck portion of a container when a molten gob of glass is pressed into a parison or preform. A neck ring and plunger assembly of generally conventional construction is shown in EP-A-336657. This comprises a neck ring assembly which has a stepped interior contour comprising a cylindrical portion having an upper surface and a lower enlarged annular portion. A guide ring is received in the neck ring assembly and has a stepped exterior contour including a cylindrical portion, which is received in the cylindrical portion of the neck ring assembly, having an upper surface and a lower, enlarged annular portion which is received in the lower enlarged annular portion of the neck ring assembly. The plunger assembly, which includes pressure exerting means in the form of a spring, moves a plunger through the neck ring assembly and the guide ring to form glass parisons. While the parison is being formed, the outer surface of the neck portion is formed by cooperation between the neck ring assembly and the guide ring. The guide ring incurs substantial wear in use, which results in a gap appearing between the neck ring assembly and the guide ring resulting in the formation of an annular flange of glass extending outwardly from the neck portion of the parison. Such a flange (known as a flanged finish) is very undesirable, especially as it is susceptible to breakage, leaving a sharp surface. It is one of the objects of the present invention to provide a neck ring and plunger assembly in which the formation of a flanged finish as a result of normal wear of the neck ring is avoided. The present invention provides a neck ring and plunger assembly for use in a glassware forming machine, comprising a neck ring having a stepped interior contour comprising a cylindrical portion having an upper surface and a lower enlarged annular portion, a guide ring having a stepped exterior contour including a cylindrical portion arranged to be received in the cylindrical portion of the neck ring and having an upper surface, and a lower enlarged annular portion arranged to be received in the annular portion of the neck ring, a plunger assembly including pressure exerting means characterized in that the height of the cylindrical portion of the neck ring is greater than the height of the cylindrical portion of the guide ring by an amount (Z) and the pressure exerting means acts on the guide ring to urge the upper surface of the guide ring into engagement with the upper surface of the neck ring, thus to ensure these surfaces are maintained in engagement as the surface wears. The sole figure is an axial cross-sectional view of a neck ring/plunger assembly illustrating the present invention. The plunger assembly includes a plunger 10 which is secured to a plunger holder 12, a plunger mounting adapter 14 which is connected to a vertically reciprocating piston 16 and a kickback basket assembly 18. When the piston 16, and hence, the plunger 10 is lowered, the lower surface of an adapter annular support collar 20 engages a spacer 22 which is supported at the bottom of a centering sleeve 24 of the kickback basket assembly 18. Further downward displacement results in the centering sleeve 24 forcing a kickback basket 26 down compressing a spring 30. The top of a spring retainer 32 is defined by a plunger assembly cap 40 which is secured to a retainer plate 42. A float cover 44 having a depending central collar 46 is located on top of the cap 40 with the collar 46 being located within the central opening 48 in the cap. A complete description of the plunger assembly is disclosed in U.S. Patent 4836839. To form a parison 49, a mold cavity is defined with a pair of opposed side molds 50, an end mold 52 and a pair of opposed neck ring assemblies 54 each having a neck ring 56 and a guide ring 58 for forming the outer surface of the neck portion of the parison 49. Each neck ring 56 has a stepped interior contour 62, comprising a cylindrical portion 63 which is bounded at the top defining an upper surface 84 and has a first height X, and a lower, enlarged annular portion 66 which has an annular top surface 74 which extends to the cylindrical portion 63 and has a second height Y. The guide ring 58 has a stepped exterior contour 68 which is to be received by the stepped contour 62 of the neck ring 56. The guide ring 58 has a cylindrical top portion 64 having an upper surface 82 which engages the upper surface 84 of the neck ring interior contour 62 and has lower enlarged annular portion 72 which is received by the neck ring annular portion 66. While the total height of this guide ring stepped exterior contour 68 corresponds to the total height (X + Y) of the stepped interior contour 62, an upper surface 70 of the annular portion 72 of the guide ring is defined to establish a selected clearance Z with the top surface 74 of the lower portion 66 of the neck ring interior contour. As illustrated, an upper beveled surface 80 of the centering sleeve 24 is forcefully pushed upwardly against the guide ring 58, thereby forcing the upper surface 82 of the guide ring against the corresponding neck ring surface 84. Since another annular clearance C, at least as large as clearance Z, is defined between a top 86 of the kickback basket 26 and the cap 40, as the upper surface 82 of the guide ring wears, the kickback spring 30 will urge the kickback basket 26, and hence, the centering sleeve 24 upwardly. The sleeve 24 will, accordingly, continue to force the guide ring 58 upwardly into engagement with the neck ring 56 until clearance Z is eliminated. By maintaining these surfaces in forceful engagement throughout prolonged machine operation, the formation of a flanged finish which normally results from the separation of these two surfaces when the upper surface 82 of the guide ring wears, can be prevented.

Claims: A neck ring and plunger assembly for use in a forming machine, comprising a neck ring (56) having a stepped interior contour comprising a cylindrical portion (63) having an upper surface (84) and a lower enlarged annular portion (66), a guide ring (58) having a stepped exterior contour including a cylindrical portion (64) arranged to be received in the cylindrical portion (63) of the neck ring and having an upper surface (82), and a lower enlarged annular portion (72) arranged to be received in the annular portion (66) of the neck ring, a plunger assembly including pressure exerting means (30) characterized in that the height of the cylindrical portion (64) of the guide ring (58) is greater than the height of the cylindrical portion (63) of the neck ring (56) by an amount (Z) and the pressure exerting means (30) acts on the guide ring (58) to urge the upper surface (82) of the guide ring (58) into engagement with the upper surface (84) of the neck ring (56), thus to ensure these surfaces are maintained in engagement as the surface (82) wears. A neck ring and plunger assembly according to claim 1 wherein the plunger assembly comprises axially displaceable plunger means (16), and centering sleeve means (24) for guiding the axial displacement of the plunger means (16) and received in a central bore (53) of the neck ring assembly (56) characterized in that the sleeve means (24) is urged by the pressure exerting means (3) in the form of a spring against the guide ring (58) thus to urge the surface (82) of the guide ring into engagement with the surface (84) of the neck ring assembly.

Inventors: DOUGLAS ROBERT J, TRAHAN ALBERT J, DOUGLAS, ROBERT J., TRAHAN, ALBERT J.
Applicants: EMHART GLASS MACH INVEST, EMHART GLASS MACHINERY INVESTMENTS INC.
Application year: 1990
Main classification: C03B9
IPC codes: C03B9