Mold assemblies for GOB pressing and methods for GOB pressing glass articles using such mold assemblies

Abstract

A mold assembly for gob pressing a glass article is disclosed. The mold assembly comprises a mold, a plunger, and an overflow region. The mold defines an open cavity configured to receive a gob of a glass-containing material in a molten state. The plunger is configured to be actuated towards the mold and into the open cavity to press the gob into a semi-closed volume that has a three-dimensional (3D) shape defined by the mold and the plunger to form the glass article with the 3D shape. The overflow region is configured to receive an excess portion of the gob when pressed by the plunger.

Description

MOLD ASSEMBLIES FOR GOB PRESSING AND METHODS FOR GOB PRESSING GLASS ARTICLES USING SUCH MOLD ASSEMBLIESCROSS REFERENCE TO RELATED APPLICATION

[0001] This application claims the benefit of priority under 35 U.S.C. §119 of U.S. Provisional Application Serial No. 63 / 641544 filed on May 2, 2024, the content of which is relied upon and incorporated herein by reference in its entirety their entireties.FIELD

[0002] The present disclosure relates to glass pressing and, more particularly, to mold assemblies and methods for forming thin, three-dimensional near net shape (“3DNNS”) glass articles via gob pressing.BACKGROUND

[0003] Glass cover articles for electronic devices, such as smart phones, smart watches, tablets, and other electronic devices, are desirably formed with three-dimensional (3D) shapes and non-uniform thicknesses. Such 3D glass cover articles and similarly-shaped 3D glass articles (hereinafter “3D glass article(s)” or “glass article(s)”) may be formed using a variety of processes. One method of forming 3D glass articles includes machining the articles from thick pieces of glass that are initially provided as flat sheets of glass having uniform thickness. Another method of forming 3D glass articles includes using a 3D forming process with a glass blank / preform (e.g., sagging or sheet reforming) or with a glass sheet (e.g., vacuum sagging). However, these existing 3D forming processes may not be able to form 3D glass articles that have variable thicknesses and / or meet target thickness tolerances along the as-formed part without additional machining. Accordingly, these existing methods may utilize thickness overcompensation of the as-formed glass articles followed by significant material removal to achieve the target shape and thickness tolerances, leading to appreciable machining time and material waste.

[0004] Gob pressing is another 3D forming process that can be used to form 3D glass articles. In a gob pressing process, a volume of molten glass or glass ceramic from a melt (known as a “gob”) is placed in a mold through an opening or gathering at the top of the mold. A ring can be located on the top of the mold to cover a portion of the opening.A plunger is configured to be inserted through the ring and moved towards the mold to compress the gob against a shaped surface of the mold. The mold and the plunger (and optionally the ring) define a closed volume into which the gob is compressed during the gob pressing process. The movement of the plunger towards the mold reduces the closed (or compression) volume, thereby forcing the gob to conform to a desired 3D shape.

[0005] Applicant has developed gob pressing systems, tooling, and methods for fabrication of gob-pressed 3DNNS glass articles that overcome some of the existing challenges. However, some challenges still remain. For example, since the gob is typically pressed into a closed volume, a pressure field within the volume tends to increase during the pressing process. Under certain conditions, the increasing pressure field may cause the molten glass to infiltrate unintended areas of the pressing system, and irreversibly damage the system. An example of such infiltration is illustrated in FIG. 11. Consequently, it would be advantageous to provide gob pressing systems, tooling, and methods that overcome these and other challenges for forming 3DNNS glass articles.SUMMARY

[0006] A first aspect of the present disclosure includes a method for gob-pressing a glass article, comprising: depositing a gob of a glass-containing material in a molten state into an open cavity of a mold; actuating a plunger towards the mold body and into the open cavity to press the gob into a semi -closed volume having a three-dimensional (3D) shape defined by forming surfaces of the mold and the plunger to form the glass article with the 3D shape; and directing an excess portion of the gob into an overflow region during the actuating.

[0007] A second aspect of the present disclosure includes a mold assembly for gob pressing a glass article, comprising: a mold defining an open cavity configured to receive a gob of a glass-containing material in a molten state; a plunger configured to be actuated towards the mold and into the open cavity to press the gob into a semi-closed volume having a three-dimensional (3D) shape defined by the mold and the plunger to form the glass article with the 3D shape; and an overflow region configured to receive an excess portion of the gob when pressed by the plunger.BRIEF DESCRIPTION OF THE DRAWINGS

[0008] FIG. 1 is a cross-sectional representation of a first embodiment of a mold assembly according to embodiments of the present disclosure;

[0009] FIG. 2 is a cross-sectional representation of a second embodiment of a mold assembly according to embodiments of the present disclosure;

[0010] FIG. 3 is a cross-sectional representation of a third embodiment of a mold assembly according to embodiments of the present disclosure;

[0011] FIGS. 4 and 5 are a cross-sectional representations of a fourth embodiment of a mold assembly with a plunger shown in different positions according to embodiments of the present disclosure;

[0012] FIG. 6 is a cross-sectional representation of a fifth embodiment of a mold assembly according to embodiments of the present disclosure;

[0013] FIGS. 7 and 8 are cross-sectional representations of a reference mold assembly with a plunger shown in different positions to provide a foundational background for describing the mold assemblies of FIGS. 1-6;

[0014] FIG. 9 is a perspective view of a glass part according to aspects of the present disclosure;

[0015] FIG. 10 is a cross-sectional representation of a reference mold assembly with glass infiltration due to a pressure field during pressing;

[0016] FIG. 11 is a digital image of a plunger of a reference mold assembly with glass infiltration shown on surfaces thereof;

[0017] FIG. 12 is a flow chart of various steps of a method for gob pressing a glass article according to embodiments of the present disclosure; and

[0018] FIGS. 13-15 are schematic depictions of gob-pressed parts that can be formed using mold assemblies according to the Example.DETAILED DESCRIPTION

[0019] For the purposes of promoting an understanding of the principles of the disclosure, reference will now be made to the embodiments illustrated in the drawings and described in the following written specification. It is understood that no limitation tothe scope of the disclosure is thereby intended. It is further understood that the present disclosure includes any alterations and modifications to the illustrated embodiments and includes further applications of the principles disclosed herein as would normally occur to one skilled in the art to which this disclosure pertains.

[0020] As used herein, the term “and / or,” when used in a list of two or more items, means that any one of the listed items can be employed by itself, or any combination of two or more of the listed items can be employed. For example, if a composition is described as containing components A, B, and / or C, the composition can contain A alone; B alone; C alone; A and B in combination; A and C in combination; B and C in combination; or A, B, and C in combination.

[0021] In this document, relational terms, such as first and second, top and bottom, and the like, are used solely to distinguish one entity or action from another entity or action, without necessarily requiring or implying any actual such relationship or order between such entities or actions.

[0022] As used herein, the term “about” means that amounts, sizes, formulations, parameters, and other quantities and characteristics are not and need not be exact, but may be approximate and / or larger or smaller, as desired, reflecting tolerances, conversion factors, rounding off, measurement error and the like, and other factors known to those of skill in the art. When the term “about” is used in describing a value or an end-point of a range, the disclosure should be understood to include the specific value or endpoint referred to. Whether or not a numerical value or end-point of a range in the specification recites “about,” the numerical value or end-point of a range is intended to include two embodiments: one modified by “about,” and one not modified by “about.” It will be further understood that the end-points of each of the ranges are significant both in relation to the other end-point, and independently of the other end-point.

[0023] Concentrations, amounts, and other numerical data may be expressed or presented herein in a range format. It is to be understood that such a range format is used merely for convenience and brevity and thus should be interpreted flexibly to include not only the numerical values explicitly recited as the limits of the range, but also to include all the individual numerical values or sub-ranges encompassed within that range as if each numerical value and sub-range was explicitly recited. As an illustration, a numerical range of “about 1 to about 5” should be interpreted to include not only the explicitlyrecited values of about 1 to about 5, but also to include individual values and sub-ranges within the indicated range. Thus, included in this numerical range are individual values such as 2, 3, and 4, the sub ranges such as from 1-3, from 2-4, from 3-5, etc., as well as 1, 2, 3, 4, and 5 individually. The same principle applies to ranges reciting only one numerical value as a minimum or maximum. Furthermore, such an interpretation should apply regardless of the breadth of the range or the characteristics being described by the range.

[0024] The terms “substantial,” “substantially,” and variations thereof as used herein, unless defined elsewhere in association with specific terms or phrases, are intended to note that a described feature is equal or approximately equal to a value or description. For example, a “substantially planar” surface is intended to denote a surface that is planar or approximately planar. Moreover, “substantially” is intended to denote that two values are equal or approximately equal. In some embodiments, “substantially” may denote values within about 10% of each other, such as within about 5% of each other, or within about 2% of each other.

[0025] Directional terms as used herein — for example up, down, right, left, front, back, top, bottom, above, below, and the like — are made only with reference to the figures as drawn and are not intended to imply absolute orientation.

[0026] As used herein the terms "the," "a," or "an," mean "at least one," and should not be limited to "only one" unless explicitly indicated to the contrary. Thus, for example, reference to "a component" includes embodiments having two or more such components unless the context clearly indicates otherwise.

[0027] Disclosed herein are embodiments of mold assemblies and methods for forming thin, three-dimensional near net shape (“3DNNS”) glass articles via gob pressing. The mold assemblies disclosed herein are configured to manage or eliminate pressure fields that may develop during the pressing process. Such management or elimination of pressure fields can help avoid glass infiltration into unintended areas of the pressing system, thereby reducing downtime for maintenance and extending the operational life of the mold assemblies. The glass articles formed from such mold assemblies can have improved dimensional accuracy and low dimensional (shape) variability due to the management or elimination of the pressure fields during the pressing process.

[0028] FIGS. 7 and 8 illustrate a reference gob pressing process that forms a glass article using a reference mold assembly 700 to provide a foundational background for describing the mold assemblies of the present disclosure. The reference mold assembly 700 includes a mold 704 that is configured to receive a gob 706 of a glass-containing material (e.g., molten glass gob, molten glass) from a source and retain the gob 706 therein. The mold 704 comprises a bottom end 708 and a top end 712 disposed opposite the bottom end 708. The mold 704 has an open cavity 714 that opens to the top end 712 of the mold 704. Disposed within the open cavity 714, the mold 704 has a first forming surface or mold surface 716. The mold surface 716 is configured to define the shape and features (e.g., the mold pattern) imparted to an outside surface of the glass article 400 (FIG. 8) during gob pressing with the reference mold assembly 700. It should be appreciated that the reference process is described with reference to the glass article 400 shown in FIG. 8 for simplicity and ease of understanding only. The glass article formed by the reference process can be any glass article or part configured to be formed via gob pressing.

[0029] The gob 706 can be deposited into the mold 704 (e.g., through the open cavity 714) in a shaped or unshaped form. The gob 706 (e.g., glass or glass ceramic) can be placed at a center of the mold 704, as depicted in FIG. 7. The gob 706 can also be placed approximately at the center or spaced from the center.

[0030] The gob 706 is deposited into the mold 704 according to predetermined gathering conditions. For example, the glass (e.g., glass or glass-ceramic) can be configured with a target temperature, target shape, target mass / weight / volume, and target viscosity prior to deposition or delivery into the mold. There are several considerations for determining the target temperature, target shape, target mass / weight / volume, and target viscosity of the gob 706. For instance, temperature will dictate the viscosity of the glass as it enters the mold and, thus, its ability to fill out the mold (if desired) prior to pressing the glass with the plunger. Another consideration is the die design (e.g., the mold pattern and the plunger pattern), which includes the thickness, tightness of tolerances and / or scale of the features in the die design (e.g., how far the glass has to travel and / or the size or smallness of the features). Another consideration is the amount of pressure utilized in the pressing force. Additional consideration can include a size of the near net shape component, a complexity of the mold pattern, a complexity of the plunger pattern, anda composition of the glass. The gathering conditions are configured to be compatible with the specifications of the reference mold assembly 700.

[0031] The gob 706 can be deposited into the mold 704 in a mounded form or a flattened / shaped form. The gob 706 can have a viscosity of at least 1000 P, such as in a range of from about 1500 P to about 7000 P, but may be otherwise, such as from about 10 P to about 500 P. The gob 706 may have a smaller or a larger viscosity range. The gob 706 can be a glass, such as soda lime glass or a multi-component silicate glass. The glass can be a precursor glass that is subsequently heat treated (cerammed) to become a glass-ceramic.

[0032] As shown in FIGS. 7 and 8, the reference mold assembly 700 also includes a plunger 720 that is configured to actuate towards or with the mold 704 to press the gob between the mold 704 and the plunger 720. The plunger 720 has a second forming surface or plunger surface 722 that is configured to define the shape and features (e.g., the plunger pattern) imparted to an inside surface of the glass article 400 during the pressing with the reference mold assembly 700. As such, each of the mold surface 716 and the plunger surface 722 (e.g., the plunger surface) is configured to impart or form shape and features (e.g., in the negative) into respective areas of the gob 706 during the pressing with the reference mold assembly 700 to form the glass article 400 with an accurate, as-formed 3D shape.

[0033] The plunger 720 of the reference mold assembly 700 is actuated towards the mold 704, as depicted in FIG. 7, to press the gob 706 into a closed volume 726 defined by the mold surface 716 and the plunger surface 722, as depicted in FIG. 8, to form the glass article 400. The plunger 720 is configured to translate along an actuation axis (arrow 728 in FIGS. 7 and 8) towards the mold 704 in a first direction when actuated to press the gob 706 into the closed volume 726. The plunger 720 is configured to translate along the axis 728 away from the mold 704 in a second direction opposite the first direction when actuated to release the gob-pressed glass article 400 from the reference mold assembly 700.

[0034] The reference mold assembly 700 may further comprise a ring portion 732 configured to cover a portion (e.g., a peripheral portion) of the open cavity 714 of the mold 704. The ring portion 732 can be configured to define a portion of the closed volume 726. For example, when the plunger 720 is actuated towards the mold 704 and presses thegob 706, the gob 706 is squeezed between the plunger surfaces 722 of the plunger 720 (e.g., the plunger pattern) and the mold surfaces 716 of the mold 704 (e.g., the mold pattern) with portions of the gob 706 radiating away from an origin of the initially deposited gob in directions that are substantially parallel to the surfaces defining the plunger and mold patterns until contact with the ring portion 732.

[0035] The ring portion 732 can be separate from (i.e., not an integral part of) the mold 704 and the plunger 720. In this configuration, the ring portion 732 can be disposed on the mold 704 (e.g., on the top end 712 of the mold 704) and configured to define a ring opening through which the plunger 720 moves and makes sliding contact with the ring portion 732 when the plunger 720 is actuated during a pressing operation. Alternatively, the ring portion can be an integral part of the mold 704 such that the mold is a monolithic component.

[0036] During the pressing operation while the plunger 720 is actuated towards the mold 704, the closed volume 726 (sometimes referred to as a compression volume) decreases or reduces until the plunger 720 is actuated to or reaches a predetermined position or distance from the mold 704, such as the position of the plunger 720 shown in FIG. 8. The plunger 720 is actuated with a pressing speed and a pressing force configured to ensure the plunger 720 reaches the predetermined distance and the gob 706 is pressed so as to completely fill the closed volume 726. The plunger 720 moves quickly enough such that the glass remains sufficiently fluid to move through the mold.

[0037] As shown in FIG. 8, the closed volume 726 is defined by the mold 704 (e.g., the mold pattern) and the plunger 720 (e.g., the plunger pattern). The closed volume 726 is defined by the mold surface 716 and the plunger surface 722 when one or more of (i) a position of the plunger 720 reaches a predetermined position relative to the mold 704 and (ii) a pressure on the gob-filled closed volume 726 (e.g., the glass article 400) and / or on the plunger 720 reaches a predetermined pressure. As used herein, “closed volume” means that the volume defined by the mold surface 716 and plunger surface 722 is configured to substantially retain the molten glass contained therein during the pressing with the reference mold assembly 700. The volume is not hermetically sealed so that air or gas occupying the closed volume 726 during the pressing can escape as the gob fills the closed volume 726.

[0038] The closed volume 726 has a three-dimensional shape such that when the gob 706 is pressed into the closed volume 726, the gob-pressed glass article 400 is formed with a three-dimensional shape corresponding to the three-dimensional shape of the closed volume 726.

[0039] Each of the mold surface 716 (e.g., the mold pattern) and / or plunger surface 722 (e.g., the plunger pattern) can have a configuration of features that is imparted / formed (e.g., in the negative) into respective areas or regions of the gob 706 when pressed by the plunger 720 so as to form the gob-pressed part 400 with a three-dimensional shape (i.e., with minimal or no post-processing). The surfaces of the glass part 400 imparted / formed via the mold pattern and the plunger pattern can be planar and / or curved in portions though the surfaces are configured with the three-dimensional shape.

[0040] The glass part 400 further includes molded features or attributes that are imparted / formed via the mold pattern and / or the plunger pattern during the pressing. The molded features can include one or more of holes (circular, rectangular, elliptical, etc.), a stepped edge (e.g., a cut-out through which device buttons are positioned), curved sides (e.g., extending upward from a generally flat portion of the component and / or curving inwardly over itself), among other features. Other molded features include non-uniform thickness, including a thicker edge, a thicker comer, a thicker portion or a thinner portion of the component (e.g., raised shape or raised region (thicker), an embedded shape or embedded region (thinner), among other configurations). Another non -limiting example of a molded feature includes textured surface finishes that can be embossed from pressing contact with the mold pattern and / or plunger pattern.

[0041] FIG. 9 depicts an example of a gob-pressed glass part 900 that can be made using the reference mold assembly 700. For example, the glass part 400 described with reference to FIGS. 7 and 8 may have the features of the glass part 900 now described. The glass part 900 includes a body 904 having major surfaces, such as a first surface, such as an inside surface 908 or interior surface and a second surface, such as an outside surface 912 or exterior surface, spaced apart and facing away from the inside surface 908 of the body 904. Spacing between the inside surface 908 and the outside surface 912 defines a thickness t of the glass part 900. If the glass part 900 is positioned on or adjacent to an electronic device, the inside surface 908 may be on the inside of the assembly,whereas the outside surface 912 may be on the outside of the assembly or outward facing.

[0042] Each inside surface 908 and outside surface 912 may be smooth, characterized by surface roughness. The inside surface 908 and the outside surface 912 may have a different surface roughness from one another, such as with the inside surface 908 having greater roughness. The surface roughness of one or both of the inside surface 908 and the outside surface 912 can be imparted by the reference method of forming the glass part 900 (e.g., gob pressing using a reference mold 700).

[0043] A portion (e.g., a central portion) of the glass body 904 can include a flat or planar section 916. The portions of the inside surface 908 and the outside surface 912 defined by the flat section 916 of the glass body 904 are generally flat or planar. The flat section 916 may be configured to cover at least part of a display area of an electronic device. The glass body 904 can also include a bend or curved section 920 disposed adjacent to at least a portion of the flat section 916. The bend section 920 can be adjacent to one side (e.g., a long or elongated side) of the flat section 916, giving the glass part (not shown) a slide shape.

[0044] The glass body 904 can include two, separate bend sections 920 adjacently disposed on opposite sides of the flat section 916, giving the glass part (not shown) a sled shape. The bend section 920 can surround a periphery of the flat section 916, giving the glass part 900 a dish shape. The portions of the inside surface 908 and the outside surface 912 defined by the bend section 920 of the glass body 904 are generally curved. The central portion of the glass body 904 can be curved (instead of flat or planar) and the glass body may not contain a bend section 920, giving the glass part a contour shape. The glass body 904 can have an edge surface or edge 924 that extends between the inside surface 908 and the outside surface 912.

[0045] The bend section 920 can comprise at least one bend with a bend radius or curvature. The bend section 920 can include at least two bends, at least three bends, or greater than three bends with each bend having the same bend radius or a different bend radius. The bend radius can be constant having a fixed radius with a constant center point, or the bend radius can be variable, as in the case of a spline structure. The bend can be a complex bend that has a changing radius, such as described by a Burmester curve. The bend can also have a bend angle. The bend angle can be measured using the insidesurface 908, the outside surface 912, or a central plane disposed along a midpoint between the inside and outside surfaces 908, 912 of the glass body 904, or the bend angle can be measured using a centerline disposed between the inside and outside surfaces 908, 912, if the glass body 904 is viewed in cross-section. The bend angle and the bend radius can be selected based on a peripheral side geometry of the electronic device.

[0046] The bend angle can be from greater than 0° to 90°. The bend angle can be greater than 90°. The bend radius can be about 1 mm or greater. The bend radius can be from about 0.25 mm to about 20 mm, about 0.5 mm to about 20 mm, about 1 mm to about 20 mm, about 1 to about 15 mm, about 1 mm to about 10 mm, about 1 mm to about 5 mm, about 2 mm to about 20 mm, about 2 to about 15 mm, about 0.75 mm to about 10 mm, about 2 mm to about 10 mm, about 2 mm to about 5 mm, about 5 to about 15 mm, about 5 mm to about 10 mm, or about 1 mm to about 20 mm, and also comprising all sub-ranges and sub-values between these range endpoints. The bend radius can be about 0.25, 0.5, 0.75, 1.0, 1.25, 1.5, 1.75, 2.0, 2.25, 2.5, 2.75, 3.0, 3.5, 4.0, 4.5, 5.0, 6.0, 7.0, 8.0, 9.0, 10.0, 15.0, 20.0 mm ormore.

[0047] The spacing between the inside surface 908 and the outside surface 912 may define the thickness t of the glass part 900. The thickness t can be measured as the most direct distance between the inside surface 908 and the outside surface 912 at a given location on the part 900 and may vary between locations. The thickness t can be measured in a direction normal to one or both of the inside surface 908 and the outside surface 912.

[0048] The thickness t of the glass part 900 (e.g., wall thickness) can be in a range of from about 0.3 mm to about 4.0 mm, about 0.5 mm to about 4.0 mm, about 0.75 mm to about 3.0 mm, or about 0.9 mm to about 2.1 mm, and also comprising all sub-ranges and subvalues between these range endpoints. The thickness t can be about 0.3, 0.4, 0.5, 0.6, 0.7, 0.75, 0.8, 0.9, 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9, 3.0, 3.1, 3.2, 3.3, 3.4, 3.5, 3.6, 3.7, 3.8, 3.9, or 4.0 mm. For some such parts, a variation of the thickness t of the glass part can be within ± 200 pm, ± 175 pm, ± 150 pm, ± 125 pm, ± 100 pm, ± 75 pm, ± 50 pm, ± 20 pm, or ± 20 pm. For some such parts, a variation in the thickness of the glass body is within ± 10 pm, ± 20 pm, ± 30 pm, ± 40 pm, ± 50 pm, ± 60 pm, ± 70 pm , ± 80 pm, ± 90 pm, ± 100 pm, ± 125 pm, ± 150 pm ± 200 pm, or ± 250 pm of an average thickness of the glass body 104, 204, 304. For other parts with more varied thicknesses, a variation of the thicknesst of the glass part at different locations thereon may be greater than 200 pm, 175 pm, 150 pm, 125 pm, 100 pm, 75 pm, 50 pm, 20 pm, or 20 pm. For some such parts, a variation in the thickness of the glass body is greater than 10 pm, 20 pm, 30 pm, 40 pm, 50 pm, 60 pm, 70 pm, 80 pm, 90 pm, 100 pm, 125 pm, 150 pm, 200 pm, or 250 pm of an average thickness of the glass body.

[0049] The glass part 900 can be transparent and have an optical transmission (total transmission) greater than 85% in a wavelength range of 400 nm to 800 nm (such as at some, most i.e., >50%, or all wavelengths therein) at thicknesses disclosed herein, such as through 1 mm of the glass. The glass part 200 can be transparent and have an optical transmission greater than 75%, 80%, 85%, 87%, 90%, or 93% in a wavelength range of 400 nm to 800 nm (such as at some, most i.e., >50%, or all wavelengths therein) at a thickness of the respective part, and / or such as at thicknesses disclosed herein, such as through 1 mm of the glass. In other embodiments, glass of part disclosed herein can be opaque or have a transmission less than 75%, such as less than 40%, such as less than 10% in a wavelength range of 400 nm to 800 nm (such as at some, most i.e., >50%, or all wavelengths therein) at a thickness of the respective part, and / or such as at thicknesses disclosed herein, such as through 1 mm of the glass.

[0050] The glass part 900 can include one or more features (e.g., molded feature(s) 932) that can be formed in situ during the gob-pressing process. The glass part 900 includes the inner surface 908 (e.g., inner side wall of ahand-held consumer electronics device) with the bend section 920 of the glass body 904 configured as a raised, perimetrical wall or edge surrounding the flat section 916 of the glass body 904. The glass part 900 includes two different molded features 932, such as edge 932a and holes 132b. One molded feature comprises a discontinuous edge 932a located along the edge of the bend section 920 (e.g., shown as a stepped, or cut-out feature imparted during gob-pressing). Another molded feature comprises two holes 932b configured to extend entirely through the glass body 904 from the inside surface 908 to the outside surface 912. The holes 932b may be positioned to correspond to locations of lens or apertures of a cell phone camera.

[0051] Various other molded features 932 can be formed in or on the glass part 900 during the gob-pressing process. The molded feature is selected from a hole, a slot, a stepped edge, an indented portion, a raised portion, a non-uniform thickness, a thick portion, a thick comer, a thick edge, a thin portion, a thin edge, an inner surface pattern, an outer surface pattern, an edge surface pattern, an embossed feature, a varying radii of at least one of:an inside comer, and outside comer, an inside edge and an outside edge, a contoured outer edge, and a contoured inner surface. If the glass part 900 includes one or more molded features 932, the determination of an average wall thickness along a section configured with a constant wall thickness (e.g., except for a thickness contribution from the molded feature) may exclude the molded feature from the average wall thickness. Alternatively, if the glass part 900 includes one or more molded features 932, the determination of an average wall thickness along a section configured with a constant wall thickness may include the molded feature as a portion of the average wall thickness.

[0052] As schematically illustrated in FIG. 10, the reference mold assembly 700 may be susceptible to glass infiltration 750 in the region between the plunger 720 and the ring 732 due to unmanaged pressure fields during pressing. FIG. 11 is a digital image of a plunger 720 of a reference mold assembly that is damaged from glass infiltration 750.

[0053] Referring now to FIGS. 1-6, embodiments of mold assemblies 100, 200, 300, 400, 500 configured to manage or eliminate pressure fields are now described. Each mold assembly 100, 200, 300, 400, 500 includes a mold 104, 204, 304, 404, 504 and a plunger 120, 220, 320, 420, 520 positioned generally in the manner described with reference to FIGS. 7 and 8 except as described otherwise hereinbelow. The mold assemblies 100, 200, 300, 400, 500 further include an overflow region 136, 236, 336, 436, 536 configured to receive an excess portion 140, 240, 340, 440 of the gob when pressed by the plunger 120, 220, 320, 420, 520. The mold assemblies 100, 200, 300, 400, 500 can include a ring portion 132, 232, 332, 432, 532 configured to direct the excess portion 140, 240, 340, 440 of the gob into the overflow region 136, 236, 336, 436, 536 when pressed by the plunger 120, 220, 320, 420, 520.

[0054] According to an aspect, when the plunger 120, 220, 320, 420, 520 reaches (i) the predetermined position relative to the mold 104, 204, 304, 404, 504 and / or (ii) the predetermined pressure on the gob-filled semi-closed volume 126, 226, 326, 426, 526 (e.g., the glass article 400, 900 formed therein), the semi -closed volume 126, 226, 326, 426, 526 (e.g., as defined by the mold surfaces 116, 216, 316, 416, 516 and the plunger surfaces 122, 222, 322, 422, 522) comprises a central planar region 144 (e.g., corresponding to the planar section 916 of the glass part 900) and a bend region (e.g., corresponding to the bend region 920 of the glass part 900) adjoining a periphery of the central planar region. In the embodiments shown, a low density dotted pattern fill isused to represent the semi-closed volume 126, 226, 326, 426, 526 filled with the glasscontaining material of the gob.

[0055] As used herein, the term “semi-closed volume” has a different meaning than the term “closed volume” described in connection with the reference mold assembly 700 of FIGS. 7 and 8. The mold assemblies 100, 200, 300, 400, 500 of FIGS. 1-6 are configured to reduce the local pressure field therein by connecting at least some local regions of the semi-closed volume 126, 226, 326, 426, 526 to atmospheric pressure during actuation of the plunger 120, 220, 320, 420, 520. In other words, the mold assemblies 100, 200, 300, 400, 500 permit at least some egress of the glass-containing material from the semi-closed volumes 126, 226, 326, 426, 526 to reduce the local pressure field therein.

[0056] As shown in FIGS. 1-6, the overflow region 136, 236, 336, 436, 536 adjoins an end of the bend region 148, 248, 348, 448, 548, in each of the mold assemblies 100, 200, 300, 400, 500. As shown in FIGS. 1-6, the central planar region 144, 244, 344, 444, 544 of the semi-closed volume 126, 226, 326, 426, 526 of each mold assembly 100, 200, 300, 400, 500 is oriented substantially normal to an actuation axis (e.g., axis 728 in FIGS. 7 and 8) of the plunger 120, 220, 320, 420, 520. According to an aspect, the gob is configured to comprise a volume of the glass-containing material that is configured to be greater than the semi-closed volume 126, 226, 326, 426, 526 (e.g., taking into account variability / tolerance of the gob volume and the semi-closed volume) so that (i) the semi-closed volume is completely filled after pressing with the plunger 120, 220, 320, 420, 520 and (ii) there is at least some of the excess portion 140 of the gob disposed in overflow region 136, 236, 336, 436, 536.

[0057] Referring now to FIGS. 1-3, further aspects of the mold assemblies 100, 200, 300 are described. In each of the mold assemblies 100, 200, 300, the ring portion 132, 232, 332 is separate from (e.g., not integral with) the mold 104, 204, 304 and the plunger 120, 220, 320. In each of the mold assemblies 100, 200, 300, the ring portion 132, 232, 332 defines a ring opening through which the plunger 120, 220, 320 moves when actuated towards the mold 104, 204, 304. The spacing or clearance between the ring portion 132, 232, 332 and the plunger 120, 220, 320 is configured to allow the plunger to slide freely through ring opening while prevent the glass-containing material of the gob from infiltrating the clearance. In embodiments, the contact surfaces between the ring portion132, 232, 332 and the plunger 120, 220, 320 may include one or more lubricants to ensure the plunger slides freely relative to the ring portion.

[0058] In the mold assembly 100 of FIG. 1, the ring portion 136 and the plunger 120 are configured to define the overflow region 136. In embodiments, the overflow region 136 can comprise one or more discrete overflow regions 136 positioned at different locations about the plunger 120. In embodiments, the overflow region 136 can comprise one continuous overflow region 136 that completely encircles the plunger 120. In embodiments in which there is one or more discrete overflow regions and / or one continuous overflow region, the excess portion 140 is configured to be directed into the overflow region 136 in a direction parallel to the actuating axis (e.g., axis 728 of FIGS. 7 and 8) of the plunger 120.

[0059] In embodiments, the overflow region 136 may not be fluidically connected to atmosphere such that the total volume of the overflow region 136 is configured to be greater than the expected volume of the excess portion of the gob to be received therein. For example, as shown in FIG. 1, the excess portion 140 of the gob (e.g., depicted using high density dotted pattern fill) fills less of the available volume within the overflow region 136, as indicated by the white space above the excess portion 140 of the gob. More specifically, if the gob volume variability is known and below a certain value, the ring portion 132 can be configured with an overflow region 136 that is larger than this gob volume variability to ensure both a correct product manufacturing and no local pressure field increase close to the clearance between the plunger 120 and the ring portion 132.

[0060] In the mold assemblies 200, 300 of FIGS. 2 and 3, the ring portion 232, 332 and the mold 204, 304 are configured to define the overflow region 236, 336. In the mold assembly 200 of FIG. 2, the overflow region 236 is integrated mainly in the mold 204. For example, the overflow region 236 shown in FIG. 2 may comprise a hole that fluidically connects the semi -closed volume 226 with atmosphere via the hole. As shown in FIG. 2, the mold surface 216, the plunger surface 222, and portions of a ring surface adjacent the plunger surface 222 define the semi-closed volume 226 (e.g., depicted using low density dotted pattern fill to represent the semi-closed volume 226 filled with the glass-containing material of the gob).

[0061] In the mold assembly 300 of FIG. 3, the ring portion 332 is spaced from the mold 304 (e.g., the ring portion 332 does not contact the mold 304) such that the overflow region 336 surrounds a periphery of the open cavity of the mold 304. In this embodiment, the excess portion 140 is configured to flow out of the semi-closed volume 326 between opposing surfaces of the ring portion 332 and the mold 304 into the overflow region 336. Assuming the gob volume variability is known and below a certain value, an approximate volume of the excess portion 340 of the gob that fills the overflow region 340 can be adjusted by controlling the gap or spacing between the ring portion 332 and the mold 304.

[0062] In embodiments in which the overflow region 236 is integrated mainly in the mold 204 (e.g., the mold assembly 200 of FIG. 2) and / or in which the ring portion 332 is spaced entirely from the mold 30 (e.g., the mold assembly 300 of FIG. 3), the excess portion 240, 340 of the gob is configured to be directed into the overflow region 236, 336 in a direction normal to the actuating axis (e.g., axis 728 of FIGS. 7 and 8) of the plunger 220, 320.

[0063] Referring now to FIGS. 4-6, further aspects of the mold assemblies 400, 500 are described. In each of the mold assemblies 400, 500, the ring portion 432, 532 is integral with (e.g., not separate from) the plunger 420, 520 and extends laterally from the plunger 420, 520. In each of the mold assemblies 400, 500, the ring portion 432, 532 and the mold 404, 504 are configured to define the overflow region 436, 536. In embodiments, the plunger 420, 520 can be configured such that when the plunger 420, 520 reaches (i) the predetermined position relative to the mold 404, 504 and / or (ii) the predetermined pressure on the gob-filled semi-closed volume 426, 526 (e.g., the glass article 400, 900 formed therein), the overflow region 436, 536 can comprise one continuous overflow region 436, 536 that completely encircles the downwardly protruding (e.g., towards the mold 404, 504) portion of the plunger 420, 520.

[0064] In embodiments, the plunger 420, 520 may have one or more protruding portions (not shown) that extend from the ring portion 432, 532 towards the mold 404, 504 and define a positive stop against the mold 404, 504 configured to coincide with the the predetermined position and / or the predetermined pressure of the plunger 420, 520. In such embodiments, the overflow region 436, 536, can comprise one or more discrete overflow regions 436, 536 positioned at different locations about the downwardly protruding (e.g., towards the mold 404, 504) portion of the plunger 420, 520. Inembodiments in which there is one or more discrete overflow regions and / or one continuous overflow region, the excess portion 440, 540 is configured to be directed into the overflow region 436, 536 in a direction parallel to the actuating axis (e.g., axis 728 of FIGS. 7 and 8) of the plunger 420, 520. In embodiments in which the ring portion 432, 532 is integral with the plunger 420, 520, the overflow region 436, 536 decreases in size (e.g., decreases in volume) when the plunger 420, 520 is actuated towards the mold 404, 504 since the ring portion 432, 532 moves with the plunger 420, 520.

[0065] In the embodiments of the mold assemblies 400, 500, there may no longer be a sensitivity to gob volume variability. This sensitivity is removed because there cannot be glass infiltration between the ring portion 432, 532 and the plunger 420, 520 is the clearance or gap there between is removed (i.e., by making the ring portion and the plunger integral). However, some additional volume of the gob may be needed to compensate since in at least some embodiments, the gob / glass may flow out through the gap between the plunger 420, 520 and the mold 404, 504 over the whole periphery thereof. To limit the additional volume that may be needed, the plunger can be further adapted to increase flow restriction to the periphery. For example, in the mold assembly 500 of FIG. 6, the surface 552 of the ring portion 532 and the surface 556 of the mold 504 that define the overflow region 536 are not parallel to one another and form a narrowing of the overflow region 536 in a direction laterally outward along the direction of gob flow during pressing. The angle of the surfaces 552, 556 shown in FIG. 6 may reduce excess glass quantity by approximately 20 g.

[0066] FIG. 12 is a flow chart of various steps of a method 1000 for gob pressing a glass article. The method 1000 includes steps 1004, 1008, and 1012. The mold assemblies 100, 200, 300, 400, 500 described above with respect to FIGS. 1-6 can be used with the steps of the method 1000. The step 1004 comprises depositing a gob of a glass-containing material in a molten state into an open cavity of a mold (e.g., mold 104, 204, 304, 404, 504). The step 1008 comprises actuating a plunger (e.g., plunger 120, 220, 320, 420, 520) towards the mold and into the open cavity to press the gob into a semi-closed volume having a three-dimensional (3D) shape defined by forming surfaces of the mold and the plunger to form the glass article (e.g., glass part 900 of FIG. 9) with the 3D shape. The step 1012 comprises directing an excess portion 140, 240, 340, 440, 540 of the gob into an overflow region 136, 236, 336, 436, 536 during the actuating.

[0067] The mold assemblies and methods disclosed herein enable gob pressing of thin glass parts with high force (e.g., several tons) via tooling configurations that allow some glass to flow out of a (normally) closed cavity. The various overflow regions can have different sizes and locations, but the general operating principle is avoidance glass pressure field build up close to the clearance or gap between the plunger and the ring portion.

[0068] When the clearance is maintained (e.g., the ring portion is configured to be separate from the plunger), overflow regions can be obtained by one or more of: limiting the ring portion stroke and allowing a gap between the ring portion and the mold; modifying the ring portion so that when it is in contact with the mold, there are at least some passages or holes present to allow some glass to leave the semi-closed volume; and modifying the mold so that even if the ring portion is in contact with the mold, there are at least some passages or holes present to allow some glass to leave the semi -closed volume. Limiting glass infdtration by any one of the aforementioned configurations limits the tooling damage and limits the propagation of cracks on the gob pressed glass article. Thus, providing better tooling durability, product quality, and product yield.

[0069] EXAMPLE

[0070] Various embodiments of the present disclosure can be better understood by reference to the following Example which is offered by way of illustration. The present disclosure is not limited to the Example given herein.

[0071] FIGS. 13-15 are schematic depictions of gob-pressed parts that can be formed using mold assemblies according to embodiments of the present disclosure. FIG. 13 shows a part 1300 gob pressed using a mold assembly similar to the mold assembly 200 of FIG. 2 with overflow regions defined by the ring portion and the mold. In particular, the part 1300 includes the excess portion of the gob in the regions 1304 shown in FIG. 13. FIG. 14 shows a part 1400 gob pressed using a mold assembly similar to the mold assembly 300 of FIG. 3 with overflow regions defined by the ring portion spaced slightly above the mold. In particular, the part 1400 includes a relatively small excess portion of the gob about the entire periphery in the regions 1404 shown in FIG. 14. FIG. 15 shows a part 1500 gob pressed using a mold assembly similar to the mold assembly 400 of FIGS. 4 and 5 with overflow regions defined by the ring portion formed integrally with the plunger and spaced slightly above the mold. In particular, the part 1500 includes arelatively large excess portion of the gob about the entire periphery in the regions 1504 shown in FIG. 15.

[0072] While the disclosure has been illustrated and described in detail in the drawings and foregoing description, the same should be considered as illustrative and not restrictive in character. It is understood that only the preferred embodiments have been presented and that all changes, modifications, and further applications that come within the spirit of the disclosure are desired to be protected.

Claims

CLAIMSWhat is claimed is:

1. A mold assembly for gob pressing a glass article, comprising: a mold defining an open cavity configured to receive a gob of a glass-containing material in a molten state; a plunger configured to be actuated towards the mold and into the open cavity to press the gob into a semi-closed volume having a three-dimensional (3D) shape defined by the mold and the plunger to form the glass article with the 3D shape; and an overflow region configured to receive an excess portion of the gob when pressed by the plunger.

2. The mold assembly of claim 1, further comprising a ring portion configured to direct the excess portion of the gob into the overflow region, the ring portion covering a portion of the open cavity of the mold.

3. The mold assembly of claim 2, wherein the ring portion covers a peripheral portion of the open cavity of the mold.

4. The mold assembly of claim 2 or claim 3, wherein the ring portion is integral with the plunger and extends laterally therefrom, the ring portion and the mold configured to define the overflow region.

5. The mold assembly of claim 4, wherein the overflow region decreases in size when the plunger is actuated towards the mold.

6. The mold assembly of claim 4 or claim 5, wherein opposing surfaces of the ring portion and the mold that define the overflow region are not parallel.

7. The mold assembly of claim 2 or claim 3, wherein the ring portion is separate from the mold and the plunger, the ring portion defining a ring opening through which the plunger moves when actuated towards the mold.

8. The mold assembly of claim 7, wherein the ring portion and the mold are configured to define the overflow region.

9. The mold assembly of claim 8, wherein the ring portion is spaced from the mold such that the overflow region surrounds a periphery of the open cavity of the mold.

10. The mold assembly of any one of claims 1-9, wherein the excess portion is directed into the overflow region in a direction normal to an actuating axis of the plunger.

11. The mold assembly of claim 7, wherein the ring portion and the plunger are configured to define the overflow region.

12. The mold assembly of claim 11, wherein the excess portion is directed into the overflow region in a direction parallel to an actuating axis of the plunger.

13. The mold assembly of any one of claim 1-12, wherein the semi-closed volume comprises a central planar region and a bend region adjoining a periphery of the central planar region, the overflow region adjoining an end of the bend region.

14. The mold assembly of claim 13, wherein the central planar region is oriented substantially normal to an actuation axis of the plunger.

15. The mold assembly of any one of claims 1-14, wherein the gob comprises a volume of the glass-containing material that is configured to be greater than the semi-closed volume.

16. A method for gob-pressing a glass article, comprising: depositing a gob of a glass-containing material in a molten state into an open cavity of a mold; actuating a plunger towards the mold and into the open cavity to press the gob into a semi-closed volume having a three-dimensional (3D) shape defined by forming surfaces of the mold and the plunger to form the glass article with the 3D shape; and directing an excess portion of the gob into an overflow region during the actuating.

17. The method of claim 16, wherein directing the excess portion of the gob comprises directing the excess portion with a ring portion that covers a portion of the open cavity of the mold.

18. The method of claim 17, wherein the ring portion covers a peripheral portion of the open cavity of the mold.

19. The method of claim 17 or claim 18, wherein the ring portion is integral with the plunger and extends laterally therefrom, the ring portion and the mold configured to define the overflow region.

20. The method of claim 19, wherein the overflow region decreases in size during the actuating of the plunger.

21. The method of claim 19 or claim 20, wherein opposing surfaces of the ring portion and the mold that define the overflow region are not parallel.

22. The method of claim 17 or claim 18, wherein the ring portion is separate from the mold and the plunger, the ring portion defining a ring opening through which the plunger moves during the actuating of the plunger.

23. The method of claim 22, wherein the ring portion and the mold are configured to define the overflow region.

24. The method of claim 23, wherein the ring portion is spaced from the mold such that the overflow region surrounds a periphery of the open cavity of the mold.

25. The method of any one of claims 16-24, wherein the excess portion is directed into the overflow region in a direction normal to an actuating axis of the plunger.

26. The method of claim 22, wherein the ring portion and the plunger are configured to define the overflow region.

27. The method of claim 26, wherein the excess portion is directed into the overflow region in a direction parallel to an actuating axis of the plunger.

28. The method of any one of claims 16-27, wherein the semi-closed volume comprises a central planar region and a bend region adjoining a periphery of the central planar region, the overflow region adjoining an end of the bend region.

29. The method of claim 28, wherein the central planar region is oriented substantially normal to an actuation axis of the plunger.

30. The method of any one of claims 16-29, wherein the gob comprises a volume of the glass-containing material that is configured to be greater than the semi -closed volume.

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