Mold assembly for glass articles

Abstract: A mold assembly (10; 40) for molding a hollow glass article comprising a mold (12) that is made up of a separable pair of mold elements (12a, 12b; 42) and a mold holder (14; 44) that surrounds a portion of the mold of substantial axial length. The mold is separable from the mold holder, and the exterior of each mold segment is provided with a plurality of cooling fins (12e; 42e). The mold holder is made up of a separable pair of mold holder sections (16, 18; 46), and each mold holder section has a fluid flow passage (20; 50) extending therethrough. The fluid flow passage is radially open to permit fluid flowing therethrough to flow inwardly against the fins of an adjacent mold element. Each mold holder section has a perforated screen (26; 56) affixed thereto to vary the distribution of the flow of fluid from the mold holder section against the fins of the adjacent mold element.

Description: Field of the Invention This invention relates to a mold assembly for use in forming hollow glass articles on a forming machine of the individual section ("I.S.") type. More particularly this invention relates to a mold assembly of the foregoing character that provides positive, indirect cooling of the article being molded in the mold assembly. Background of the Invention Hollow glass articles, such as bottles and jars, when molded by a forming machine of the I.S. type, are molded in two steps. In the first step, a preform of the finished container, which is usually called a blank or a parison, is molded by an annular mold made up of a pair of mating blank mold sections. Upon the completion of the blank molding step, the blank mold sections separate and the blank or parison is transferred to another mold station, often called the blow mold station, where it is blown into its final shape by another annular mold that is made up of another mating pair of mold sections. At the conclusion of the blow mold process, the mating sections of the blow mold are separated, and the container is removed from the forming machine for further processing. The glass gob that is formed into a parison in the blank mold of an I.S. machine is sufficiently hot to be capable of being shaped into a blank and, thus, possesses a high level of latent heat. Much of this heat must be removed before the container is removed from the blow mold of the forming machine, however, so that the finished container will be sufficiently rigid to undergo further processing without any further change in its shape. Thus, much heat must be removed from the container being formed, both during the blank molding step and the blow molding step, and unless the heat is removed at a rapid rate, the productivity of the forming machine is unduly limited. The problem of heat removal from the molds of an I.S. forming machine at a suitable rate is especially important at the blank mold station because the surface area of the parison is quite small due to the small diameter of the parison, which limits the rate at which heat can be removed, and the amount of heat to be removed is quite high due to the larger wall thickness of the parison in comparison to the wall thicknesses of a finished container. A mold arrangement according to the preamble of claim 1 is known from GB-A-1,122,899. The apparatus includes a pair of pivotable mold arms formed with jaws to carry a single annular mold and to distribute the cooling air across the mold. No mold assembly including fluid flow passages is provided for being inserted and coupled to the pivotable mold arms. A mold cooling apparatus showing a pair of pivotable mold arms for carrying individual cavity as well as multicavity mold equipment is known from EP-A-0,612,699. A diffuser plate is provided to distribute cooling flow in a space which extends along the tips of cooling fins of a mold half. The mold equipment is not shown to constitute a mold assembly which includes the fluid flow passages for distributing the cooling air over the proper mold. Further mold cooling apparatus including pivotable mold arms and individual cavity molds are known from US-A-3,586,491, EP-A-0,2,7,021, US-A-4,750,929 and FR-A-2,103,648, the latter three however with cooling passages extending through the molds themselves. The problem with the aforesaid and other prior art approaches to mold cooling of I. S. machine molds is that they add considerably to the complexity, and thus the cost, of the forming machine molds, each set of which is especially designed for only a single type of product. Thus, it is advantageous to incorporate as much of the required mold cooling structure in other structure of an I. S. molding machine that does not need to be changed every time a set of molds is replaced to permit the machine to manufacture containers of a different type, size or design. Summary of the Invention The problem to be solved by the invention is to create a mold arrangement having a mold holder which is adapted to distribute cooling fluid for a variety of molds which can be replaced in the glass forming machine. The invention is defined in claim 1. Thus, there is generally provided a mold arrangement for a glass forming machine of the I. S. type. The mold arrangement includes an annular mold which is made up of a mating pair of mold sections, whose internal surface, when the mold sections are joined end to end, defines the external shape of a glass article to be formed in an internal cavity of such annular mold, either the final shape of a glass article in the case of a blow mold or the shape of a preform of such article in a blank mold. The exterior of each of the mold sections is provided with a circumferential plurality of radially projecting, axially extending spaced apart ribs to extend the surface of the mold sections to thereby increase the rate at which latent heat can be removed from the molten glass article within the mold. The mold assembly also includes a split mold holder for holding the mold sections of a mold, as heretofore described. The mold holder, which is suitable for use with a variety of molds, surrounds the mold and directs air or other cooling fluid radially inwardly against the ribs on the exterior of the mold sections from radially open, axially extending flow passages. A split, perforated screen is applied to the interior of each of the sections of the mold holder and controls the distribution of the flow of cooling fluid against the mold Thus, by controlling the pattern of the perforations in the perforated screen, it is possible to vary the rate of cooling of the mold sections, circumferentially and axially, to equalize the rate of cooling of the glass article in the mold, notwithstanding variations in the thickness or shape of the glass article, which effects the rate at which latent heat is to be removed from different locations of the glass article. Because the sections of the mold holder, and the perforated screen sections that are attached to them, can be used with a variety of molds, the fabrication costs of the molds are reduced in comparison to costs of molds whose coolant flow passages are contained in the molds themselves. For a further understanding of the present invention and the objects thereof, attention is directed to the drawing and the following description thereof, to the detailed description of the preferred embodiment and to the appended claims. Brief Description of The Drawing Fig. 1 is a perspective view of a mold assembly according to a preferred embodiment of the adaption of the present invention to the blank mold station of an I.S. glass forming machine; Fig. 2 is a plan view, partly in section and at an enlarged scale, of the mold assembly of Fig. 1; Fig. 3 is fragmentary elevational view, in cross section and at an enlarged scale, of the mold assembly of Fig. 1; Fig. 4 is an elevational view of a mold section, from the inside or internal cavity looking outwardly, of a mold assembly according to a preferred embodiment of the adaptation of the present invention to the blow mold station of an LS. glass forming machine; Fig. 5 is a top plan view of the mold section shown in Fig. 4; Fig. 6 is a sectional view taken on line 6-6 of Fig. 4. Fig. 7 is a bottom plan view of the mold section shown in Figs. 4-6; Fig. 8 is a sectional view taken on line 8-8 of Fig. 5; and Fig. 9 is a sectional view taken on line 9-9 of Fig. 6. Detailed Description of the Preferred Embodiment A mold assembly according to the preferred embodiment of the present invention is identified generally by reference numeral 10 in Fig. 1, and is made up of an annular mold 12, which is illustrated as being suitable for use in forming a parison of a glass container. The mold assembly 10 also includes an annular mold holder 14, which encloses a substantial portion of the axial length of the mold 12 and is a part of an I.S. glass container forming machine or at least is a part that does not need to be replaced when the mold 12 is replaced. The annular mold 12 is made up of generally semi-cylindrical mold elements 12a, 12b, which, when joined end to end during a molding operation, substantially enclose a glass article being molded in a cavity therein. The mold elements 12a, 12b are separable from one another at the conclusion of a molding step, to permit a molded article to be removed therefrom, as is known in the art. In that regard, each of the mold elements 12a, 12b is provided with a tongue 12c and a groove 12d, which are diametrically opposed to one another, to permit the mold elements 12a, 12b to be precisely aligned with one another during the molding operation. Each of the mold elements 12a, 12b is also provided with a circumferentially disposed, radially projecting and axially extending series of spaced apart fins 12e, which assist in the cooling of a glass article being formed in the mold 12 to make the glass article more rigid and self-supporting than it would otherwise be at its required, elevated molding temperature. The mold holder 14 is made up of generally semi-cylindrical holder sections 16, 18, which are positioned substantially end to end during a molding step but are separable from one another at the conclusion of a molding step when the mold elements 12a, 12b separate from one another to remove a molded article therefrom. Each of the holder sections 16, 18 has a generally semi-cylindrical flow passage 20 extending axially therethrough. The passage 20, which is radially open on its interior, serves to permit cooling air or other coolant, from a source to be hereinafter described in greater detail, to flow against the fins 12e of the mold sections 12a, 12b to assist in the indirect cooling of a glass article being formed within the mold 12. Cooling air flows into the flow passage 20 of the mold holder sections 16, 18 from a plenum 22 at the bottom of the mold holder 14 through a circumferentially spaced apart series of openings 24. From the flow passages 20 the cooling air flows radially inwardly against the mold sections 12a, 12b through generally semi-cylindrical, perforated screens 26 that are affixed to the interior of the mold holder sections 16, 18. The perforations in the perforated screens 26 are sized and spaced to vary the cooling air flow distribution vertically, and circumferentially if desired, with respect to the exteriors of the mold sections 12a, 12b to equalize the rate of cooling of the article in the mold 12, notwithstanding variations in the cooling load due to localized variations in the diameter or wall thickness of the glass article. The mold holder sections 16, 18 of the mold holder 14 have less axial extent than the mold sections 12a, 12b and are centered with respect to the mold elements 12a, 12b. Thus, the cooling air from the mold holder 14 can exit from the exterior of the mold elements 12a, 12b through openings 28, 30 at the top and bottom, respectively, of the mold holder 14, in the orientation illustrated in Fig. 3. The ends of mold holder sections 16, 18 are disengageably secured to diametrically opposed pairs of vertically extending connectors 32, 34 by cap screws 36. The connectors 32, 34 have radially inwardly projecting tabs 32a, 32b and 34a, 34b respectively, that are received in slots of the mold elements 12a, 12b to accurately circumferentially position the mold holder sections 16, 18 with respect to the mold elements 12a, 12b. The tabs 32a, 32b, and 34a, 34b also engage the free ends of the screens 26 to accurately circumferentially position the screens 26 with respect to the mold holder sections 16, 18, respectively. Further, the fins 12e of the mold elements 12a, 12b have radially outwardly projecting portions 12e 1 , 12e 11 at the top and bottom, respectively, of each of the fins 12e. The portions 12e 1 , 12e 11 have shoulders that engage the top and bottom of the mold holder sections 16, 18, respectively, to accurately axially position the mold holder sections 16, 18 with respect to the mold elements 12a, 12b, respectively. Figs. 4-9 illustrate an assembly 40 that is made up of a mold section 42 contained within a section 46 of a mold holder 44. It is to be understood that the assembly 40 is annular in configuration during a molding operation with the mold section 42 joined end to end with a like mold section, not shown. Likewise, the mold holder 44 is annular in configuration during a molding operation, with the mold holder section 46 being joined end to end with a like mold holder section, also not shown. In any case, the mold assembly 40 is shown as being of a type suitable for use in an I.S. machine in performing the final, or blow, molding step on a molten glass parison of the type that has previously been formed in a parison molding assembly 10, as heretofore shown and described. Because the assembly 40 is designed for use at the blow mold station of an I.S. machine, whereas the mold assembly 10 is designed for use at the parison mold station of such a machine, the inside diameter of the mold section 42, often referred to as the cavity, will be substantially larger than that of the annular mold 12 of the mold assembly 10, and the wall thickness of a glass article in engagement with the mold section 42 will be substantially less than that in engagement with the annular mold 12. The mold section 42 is provided with a circumferentially disposed and axially extending spaced apart series of fins 42e that project outwardly from the mold section 42 to extend the outer surface of the mold section 42, and thereby increase the rate at which heat can be transferred from the glass article being blow molded in the mold assembly 40. The heat from the glass article that has transferred to the fins 42e is positively transferred away from the fins 42e by forced air cooling, and in that regard the mold holder section 46 is provided with a generally semi-cylindrical flow passage 50 extending axially therethrough. The flow passage 50 receives cooling air through an inlet 52, and is radially open on its interior to permit cooling air to flow radially outwardly from the flow passage 50 against the fins 42e of the mold section 42. A perforated screen 56, which is generally semi-cylindrically shaped, is affixed to the interior of the mold holder section 46. The perforations in the perforated screen 56 are sized and spaced to vary the cooling air flow of distribution vertically, and circumferentially if desired, to equalize the rate of cooling of an article being molded in the mold assembly 40, notwithstanding variations in cooling load due to localized variations in the diameter or wall thickness of the glass article. As is best shown in Figs. 8 and 9, the mold holder section 46 has less axial extent than the mold section 42. The mold section 42 is vertically centered with respect to the mold holder section 46 by providing the mold section 42 with an outwardly facing groove 42d that receives an inwardly projecting tongue 46a of the mold holder section 46, and further by providing the mold section 42 with a downwardly projecting flange 42f that seats against an uppermost surface 46b of the mold holder section 46. The mold section 42 is disengageably secured to the mold holder section 46 by a vertical series of spaced apart cap screws 66 (Fig. 8) that extend through the mold holder section 46 to be threadably received in the mold section 42. To assist in the proper blowing of a glass article in the mold section 42 against the interior of the mold section 42, vacuum assist is provided to help draw the molten glass article against the inside surface of the mold section 42. To that end, a diametrically opposed pair of vertical vacuum slots 70 is provided in the mold section 42, and each of the vacuum slots 70 is connected to a source of vacuum, not shown, by means of a vacuum tap 68. The vacuum in the vacuum passage 70 is being imposed on the bottom of an article being molded in the mold section 42 by a circumferentially spaced apart series of generally radially extending vacuum passage extensions 70a. The vacuum slots 70 are provided with openings 72 at the bottom thereof to ensure that the air contained within each vacuum slot 70 does not become stagnant. The best mode known by the inventors for carrying out the present invention as of the filing date hereof has been shown and described herein, but it will be apparent to those skilled in the an that suitable modifications, variations, and equivalents may be made without departing from the scope of the following claims.

Claims: A mold arrangement of a glassware forming machine, comprising: an annular mold (12) formed by a pair of separable mold elements (12a, 12b, 42) which, during a molding step, are positioned end to end to enclose a single cavity, each mold element (12a, 12b,42) having a plurality of fins (12e; 42e) on its external surface, the tips thereof defining a curved surface; a mold holder (14; 44) formed by a pair of separable mold holder sections (16, 18; 46), each mold holder section (16, 18; 46) being connected to a respective mold element (12a, 12b; 42) surrounding at least a substantial axial lenth portion of each mold element; the mold holder sections (16, 18; 46) being positioned substantially end to end during the molding steps, and - together with the respective mold element to which each mold holder section is connected - positioned separated from one another during the steps of removing the molded glass article; each of the mold holder sections (16, 18; 46) having a fluid flow passage (20; 50) which extends through the holder section and has an outlet opening to permit fluid to flow against the fins (12e; 42e) of the adjacend mold element (12a, 12b; 42) to assist in cooling the hollow glass article in the mold; a perforated screen (26, 56) which is generally semi-cylindrically shaped corresponding to the envelop surface of the tips of the fins, being provided in the outlet opening of the respective flow passage (20; 50), which screen is configured to control the rate and pattern of fluid flowing from the flow passages (20, 50) against the fins ((12e, 42a) of the respective adjacent mold element (12a, 12b; 42), characterized in that the annular mold (12) and the mold holder (14; 44) which is generally annular in shape, too, form a mold assembly (10; 40) which includes said fluid flow passages (20; 50) and said screens (26; 56) for distributing cooling air over the mold (12), in that each mold holder section (16, 18; 46) is generally semi-cylindrical in shape and designed for being inserted into, and coupled to a member of the glass forming machine which has plenum means (22) to be connected to the axially extending flow passage (20, 50) of the adjacent mold holder section, in that the fins (12e; 42e) of each mold element (12a, 12b; 42) are circumferentially disposed and extend axially at least above the mold holder sections (16, 18; 46) to form exit openings (28; 42f) for the cooling air; and in that the screen (26;56) in the outlet opening of each flow passage (20; 50) thus is configured to control the rate and pattern of fluid flowing from the axially extending flow passage (20, 50) against the axially extending fins (12e,42e) of the respective adjacent mold element (12a), 12b; 42). The apparatus according to claim 1 wherein the screen (26; 56) is affixed to the outlet opening of each mold holder section (16, 18; 46) and the perforations in each screen (26, 56) are sized and spaced in respect to the cooling fluid flow distribution as desired for the actual article to be molded. The apparatus according to claim 1 or 2 wherein said connection between mold holder section (16, 18) and mold element (12a, 12b) is made by first and second pairs of connectors (32, 34), each connector being secured to a respective free end of one of said mold holder sections (16,18), so that the connectors (32, 34) of said pairs are opposite to another, each of said mold elements (12a, 12b) having a pair of inwardly projecting recesses, each of said connectors (32, 34) having an inwardly projecting tab (32a, 32b, 34a, 34b), which is received in a respective recess of the mold elements (12a, 12b) to accurately circumferentially position each pair of connectors (32, 34) and the mold holder section (16, 18) that is secured to it with respect to an adjacent one of said mold elements (12a, 12b). The apparatus according to claim 3 wherein at least oner of the fins (12e) carried by each of said pair of mold elements (12a) 12b) has spaced apart upper and lower radially enlarged portions (12e', 12e"), said radially enlarged portions (12e', 12e") trapping an adjacent one of said mold holder sections (16, 18) to accurately axially position said each of said pair of mold elements (12a, 12b) with respect to said adjacent one of said mold holder sections, and to form an upper (28) and a lower (30) exit opening for the cooling air. The apparatus according to any of claims 1 to 4 wherein the fluid flow passage (20; 50) in each mold holder section (16, 18, 46) is substantially semi-cylindrical in shape. The apparatus according to claim 1 or 2 wherein said connection between mold holder section (46) and mold element (42) is made by threaded fastener means (66) extending through each of said mold holder sections (46), said fastener means (66) being threadably received in an adjacent on of said mold elements (42) for releasably securing said adjacent one of said mold elements (42) to the mold holder section (46) through which said fastener means extends. The apparatus according to claim 6 wherein one of said mold holder sections (46) and said mold elements (42) has a groove (42d) that faces toward an adjacent one of the other of said mold holder sections and said mold sections, and wherein the other of said mold holder sections and said mold sections has a tongue (46a) being received in said groove (42d) to accurately axially position said one of said mold holder sections and said adjacent one of said mold sections with respect to one another.

Inventors: HAUSER RUSSELL M, HAYES DAN M, NUZUM ROBERT E, OLSEN DUDLEY T, HAUSER, RUSSELL M., HAYES, DAN M., NUZUM, ROBERT E., OLSEN, DUDLEY T.
Applicants: OWENS BROCKWAY GLASS CONTAINER, OWENS-BROCKWAY GLASS CONTAINER INC.
Application year: 1997
Main classification: C03B9
IPC codes: C03B11, C03B9