Injection mold with split mold insert movement detector

Abstract

In one aspect, an injection mold may include a mold stack including a cavity insert, a core insert, and a split mold insert pair defining a molding surface for molding an external surface region of an article. First and second mold halves may include a cavity plate and a core plate to which the cavity and core inserts are mounted, respectively, and may be configured to open and close along a mold opening axis. The split mold insert pair of each mold stack may include first and second split mold inserts that are separable from one another, along a split mold insert opening axis perpendicular to the mold opening axis, when the first and second mold halves are open. A sensor may be configured to, when the first and second mold halves are closed, measure a movement, along the split mold insert opening axis, of the first split mold insert.

Description

[0001] INJECTION MOLD WITH SPLIT MOLD INSERT MOVEMENT DETECTOR

[0002] TECHNICAL FIELD

[0003] The present disclosure relates to injection molding, and more particularly to an injection mold with a split mold insert movement detector.

[0004] BACKGROUND

[0005] An injection molding system forms molded articles from a molding material. The molding material may be a plastic or resin material, such as Polyethylene Terephthalate (PET) for example. The injection molding system may heat the molding material to a molten state, in which state the molding material may be referred to as “melt.” The melt may be injected, under pressure, into a molding cavity of an injection mold.

[0006] The molding cavity may be defined by a collection of components referred to as a “mold stack.” The mold stack typically includes, among other components, a female cavity insert and a male core insert attached to a cavity plate and a core plate respectively. The cavity plate with attached cavity insert may be part of a cavity plate assembly of the injection mold, and the core plate with attached core insert may be part of a core plate assembly of the injection mold. The cavity plate assembly and core plate assembly may comprise first and second mold halves, respectively, of the injection mold. The injection mold may include multiple mold stacks, each defining a molding cavity whose shape substantially corresponds to a final cold-state shape of the article to be molded, such as a preform.

[0007] A preform may have a neck portion (or “neck finish”) having various external surface features in relief. For example, the neck portion features may include one or more of: threads for accepting and retaining a closure (e.g., a bottle cap); an anti-pilferage assembly configured to cooperate with the closure to indicate whether an end product (e.g., a beverage container filled with a beverage) has been tampered with; and a support ledge that cooperates with parts of a blow-molding system. The relief of these features is such that removal of the neck portion axially from a molding cavity defined by a unitary female cavity piece would be difficult or impossible.

[0008] For this reason, each mold stack may include a split mold insert pair, also referred as a “neck ring,” for defining the neck portion of the preform. The neck ring is designed to separate laterally into two or more halves / parts (each half / part being referred to herein as a “split mold insert”) to release the neck portion of the cooled molded article for article ejection. During injection of melt into an injection mold, a clamping force (or “clamp tonnage”) may be applied to the mold halves to hold the cavity insert and core insert of each mold stack together despite the outward force of the pressurized melt within the molding cavity. The split mold insert pair of a mold stack may have at least one tapered male projecting portion that is received within a complementary tapered female receptacle defined by an adjacent mold stack component, such as an annular cavity flange associated with the cavity insert or an annular lock ring associated with the core insert. The clamping force upon the mold halves may act axially upon the mold stack to promote a tight fit between these complementary male and female components, with a view to keeping the split mold insert pair from separating laterally from the outward force of the pressurized melt.

[0009] If mold stack components such as a split mold insert pair were to separate before the melt hardens, melt may be forced into the gap formed between the shutoff faces (facing surfaces) of the components. The result may be a thin outward projection of molding material on the molded article, referred to as “flash.” The degree of flash that may be considered tolerable may vary depending upon such factors as the application for which the molded article is intended, the location of the flash on the molded article, and aesthetic considerations.

[0010] It may be desirable to have an accurate indicator of flash risk for an injection molding system.

[0011] SUMMARY

[0012] In one aspect of the present disclosure, there is provided an injection mold, including: a mold stack including a cavity insert, a core insert, and a split mold insert pair, the split mold insert pair defining a molding surface for molding an external surface region of a molded article; a first mold half including a cavity plate to which the cavity insert is mounted; a second mold half including a core plate to which the core insert is mounted; the first mold half and the second mold half being configured to be opened and closed along a mold opening axis; the split mold insert pair of each mold stack including a first split mold insert and a second split mold insert that are separable from one another, along a split mold insert opening axis that is perpendicular to the mold opening axis, when the first and second mold halves are open; and a sensor configured to, when the first and second mold halves are closed, measure a movement, along the split mold insert opening axis, of the first split mold insert.

[0013] In some embodiments, the sensor is configured to directly measure the movement of the first split mold insert along the split mold insert opening axis.

[0014] In some embodiments, the first split mold insert is elastically deformable, the movement is an elastic deformation of the first split mold insert, and the sensor is configured to directly measure the elastic deformation of the first split mold insert along the split mold insert opening axis at a region of the first split mold insert that is susceptible to outward flexing responsive to an application of melt pressure against the molding surface during a molding cycle of the injection mold.

[0015] In some embodiments, the split mold insert pair includes a body portion and a male projecting portion projecting from the body portion, the first and second split mold inserts have respective mating faces that define a parting line through both of the body portion and the male projecting portion of the split mold insert pair, the mold stack further includes a component defining a female receptacle configured to receive and hold together the male projecting portion of the split mold insert pair when the first and second mold halves are closed, and the sensor is configured to measure the movement of the first split mold insert at the body portion of the first split mold insert.

[0016] In some embodiments, the injection mold further includes a mold component in fixed relation to the first split mold insert, and the sensor is configured to indirectly measure the movement of the first split mold insert along the split mold insert opening axis by directly measuring a movement of the mold component along the split mold insert opening axis.

[0017] In some embodiments, the mold component in fixed relation to the first split mold insert is a slide 124A) to which the first split mold insert is mounted, and the sensor is configured to directly measure the movement of the slide when the first and second mold halves are closed.

[0018] In some embodiments, the sensor is mounted in fixed relation to the cavity plate.

[0019] In some embodiments, the injection mold further includes a tonnage block, mounted to the cavity plate, that is configured to bear at least part of a clamping force upon the injection mold when the first and second mold halves are closed, and the sensor is mounted to the tonnage block.

[0020] In some embodiments, the sensor is mounted in fixed relation to the core plate.

[0021] In some embodiments, the injection mold further includes a bracket mounted to the core plate, and the sensor is mounted to the bracket.

[0022] In some embodiments, the sensor is an inductive linear position sensor.

[0023] In some embodiments, the sensor is a first sensor, the movement along the split mold insert opening axis is movement in a first direction, and the injection mold further includes a second sensor 180B) configured to, when the first and second mold halves are closed, measure a movement, along the split mold insert opening axis, of a second split mold insert of the split mold insert pair in a second direction opposed to the first direction.

[0024] In some embodiments, the second sensor is configured to directly measure the movement of the second split mold insert along the split mold insert opening axis.

[0025] In some embodiments, the second split mold insert is elastically deformable, the movement is an elastic deformation of the second split mold insert, and the second sensor is configured to directly measure the elastic deformation of the second split mold insert along the split mold insert opening axis at a region of the second split mold insert that is susceptible to outward flexing responsive to an application of melt pressure against the molding surface during a molding cycle of the injection mold.

[0026] In some embodiments, the injection mold further includes a mold component in fixed relation to the second split mold insert, and the second sensor is configured to indirectly measure the movement of the second split mold insert along the split mold insert opening axis by directly measuring a movement of the mold component along the split mold insert opening axis.

[0027] In some embodiments, the mold component in fixed relation to the second split mold insert is a slide to which the second split mold insert is mounted, and the second sensor is configured to directly measure the movement of the slide when the first and second mold halves are closed.

[0028] Embodiments may include combinations of the above features.

[0029] In another aspect of the present disclosure, there is provided a method, including: applying a clamping force to an injection mold 100), the clamping force causing a mold stack of the injection mold to become axially compressed; while the mold stack is axially compressed and before filling a molding cavity of the mold stack with melt, taking a reference reading from a sensor configured to measure movement of a split mold insert of the mold stack along a split mold insert opening axis; filling the molding cavity of the mold stack with melt; and after the filling and before removing the clamping force from the injection mold, measuring, by the sensor and based on the reference reading, a movement of the split mold insert along the split mold insert opening axis.

[0030] In some embodiments, the method further includes providing a flash risk notification based, at least in part, upon the measured movement of the split mold insert.

[0031] In some embodiments, the sensor is a first sensor, the reference reading is a first reference reading, the movement along the split mold insert opening axis is movement in a first direction, the split mold insert is a first split mold insert of a split mold insert pair of the mold stack, and the method further includes: while the mold stack is axially compressed and before the filling of the molding cavity of the mold stack with melt, taking a second reference reading from a second sensor configured to measure movement of a second split mold insert of the split mold insert pair along the split mold insert opening axis; and after the filling and before removing the clamping force from the injection mold, measuring, by the second sensor and based on the second reference reading, a movement, along the split mold insert opening axis, of the second split mold insert in a second direction opposed to the first direction.

[0032] In some embodiments, the method further includes providing a flash risk notification based, at least in part, upon the measured movement of the first split mold insert and the measured movement of the second split mold insert.

[0033] In another aspect of the present disclosure, there is provided an injection molding system, including: an injection mold including: a mold stack including a cavity insert, a core insert, and a split mold insert pair, the split mold insert pair defining a molding surface for molding an external surface region of a molded article; a first mold half including a cavity plate to which the cavity insert is mounted; a second mold half including a core plate to which the core insert is mounted; the first mold half and the second mold half being configured to be opened and closed along a mold opening axis; the split mold insert pair of each mold stack including a first split mold insert and a second split mold insert that are separable from one another, along a split mold insert opening axis that is perpendicular to the mold opening axis, when the first and second mold halves are open; and a sensor configured to, when the first and second mold halves are closed, measure a movement, along the split mold insert opening axis, of the first split mold insert and to output an indicator of the movement; and a human-machine interface 'HMI' communicatively coupled to the sensor, the HMI being operable to, based on the indicator of the movement output by the sensor, dynamically provide a flash risk notification.

[0034] Embodiments may include combinations of the above features.

[0035] Other features will become apparent from the drawings in conjunction with the following description.

[0036] BRIEF DESCRIPTION OF THE DRAWINGS

[0037] The non-limiting embodiments will be more fully appreciated by reference to the accompanying drawings, in which:

[0038] FIG. 1 is a side elevation view of an example injection mold in a closed configuration;

[0039] FIGS. 2 and 3 are a front and rear perspective view of a cavity plate assembly of the injection mold of FIG. 1 in isolation;

[0040] FIG. 4 is a rear perspective view of a stripper plate assembly of the injection mold of FIG. 1 in isolation;

[0041] FIG. 5 is a rear perspective view of a core plate assembly of the injection mold of FIG. 1 in isolation;

[0042] FIG. 6 is an axial cross-section of an example mold stack of the injection mold of FIG. 1 with an associated split mold insert movement detector; FIG. 7 is an exploded view of the mold stack of FIG. 6;

[0043] FIGS. 8A and 8B are a perspective view and a cross section, respectively, of a preform that may be molded by the mold stack of FIGS. 6 and 7;

[0044] FIG. 9 is a close up perspective view of part of the neck portion of a preform having vertical flash;

[0045] FIG. 10 a simplified schematic diagram of an injection molding system including the injection mold of FIG. 1;

[0046] FIG. 11 is a flowchart of operation of the injection molding system of FIG. 10;

[0047] FIGS. 12, 13, 14, 15, 16, 17, 18, and 19 are each axial cross sections of the mold stack of FIG. 6 at various stages of a single injection molding cycle;

[0048] FIG. 20 is a simplified schematic depiction of a portion of the mold stack of FIGS. 12-19;

[0049] FIG. 21 is an axial cross-section of another mold stack of the injection mold of FIG. 1 with a differently configured split mold insert movement detector;

[0050] FIG. 22 is a simplified schematic depiction of a portion of the mold stack of FIG. 21;

[0051] FIG. 23 is an axial cross-section of yet another mold stack of the injection mold of FIG. 1 having another differently configured split mold insert movement detector;

[0052] FIG. 24 is an axial cross-section of a further mold stack of the injection mold of FIG. 1 having an associated split mold insert movement detector in fixed relation to the core plate of the injection mold;

[0053] FIG. 25 is an axial cross-section of yet another mold stack of the injection mold of FIG. 1 having two associated split mold insert movement detectors;

[0054] FIG. 26 is an axial cross-section of the mold stack of FIG. 25 at a later time during an injection molding cycle; and

[0055] FIG. 27 depicts a human-machine interface of the molding system of FIG. 10 that may be used to provide a flash risk notification.

[0056] The drawings are not necessarily to scale and may be illustrated by phantom lines, diagrammatic representations, and fragmentary views. In certain instances, details that are not necessary for an understanding of the embodiments or that render other details difficult to perceive may have been omitted. DETAILED DESCRIPTION OF THE NON-LIMITING EMBODIMENT(S)

[0057] In this document, any use of the term “exemplary” should be understood to mean “an example of’ and not necessarily to mean that the example is preferable or optimal in some way. Terms such as “left”, “right,” “rightwardly,” “front,” “rear,” “rearwardly,” and “vertically” may be used to describe features of some embodiments in this description but should not be understood to necessarily connote an orientation of the embodiments during manufacture or use.

[0058] Referring to FIG. 1, an example injection mold 100 is illustrated in side elevation view. The injection mold 100 (or simply “mold 100”) may be part of an injection molding system including, among other components, an injection unit and a melt distribution network (neither being depicted in FIG. 1). The example injection mold 100 of FIG. 1 contains multiple mold stacks for molding multiple preforms in a single molding cycle. In the depicted embodiment, the number of mold stacks is 144, but the number of mold stacks per mold may vary in alternative embodiments. A single mold stack 111 of injection mold 100 is depicted in axial cross-section and exploded view in FIGS. 6 and 7 respectively, which are described below.

[0059] The injection mold 100 of FIG. 1 has a first mold half Hl and a second mold half H2. The first mold half Hl (which may be referred to as the “hot” mold half, because it is configured to interface with a melt distribution network such as a hot runner) includes a cavity plate assembly 102. The second mold half H2 (which may be referred to as the “cold” mold half) includes a stripper plate assembly 104, a core plate assembly 106, and a platen 108. The mold halves Hl and H2 are configured to be opened and closed along a mold opening axis AA for molded article release, as will be described. In the example injection mold 100, the cavity plate assembly 102 is static, whereas the stripper plate assembly 104 and core plate assembly 106 are each movable relative to the cavity plate assembly 102 and relative to one another. In FIG. 1, the injection mold 100 is closed, i.e., the mold halves Hl and H2 are closed.

[0060] The left and right sides of the injection mold 100 as illustrated in FIG. 1 may be referred to herein as the front and rear of the injection mold 100, respectively. This convention is used for convenience and does not necessarily connote any required orientation of the mold 100 during use. For consistency, the same convention is used throughout this document.

[0061] To facilitate comprehension of the intricate structure of the injection mold 100 of FIG. 1, various ones of its constituent substructures are depicted in isolation in FIGS. 2-5. These figures are described below.

[0062] FIGS. 2 and 3 illustrate the cavity plate assembly 102 of injection mold 100 in isolation, in front and rear perspective view, respectively. As illustrated, the cavity plate assembly 102 includes a cavity plate 110 to which a plurality of cavity inserts 112 — one per mold stack — have been mounted. In the present embodiment, the cavity inserts 112 are arranged in eight columns of 18 cavity inserts per column. The columns are oriented substantially vertically in FIG. 2. Each cavity insert 112 is held in place by a respective cavity flange 114 that is attached to the front face 109 of the cavity plate 110. Examples of a cavity insert 112 and a cavity flange 114 are also visible in the example mold stack 111 of FIGS. 6 and 7, described below.

[0063] Multiple tonnage blocks 118 (FIG. 2) are mounted to the front face 109 of the cavity plate 110. The tonnage blocks 118 are intended to protect the mold stacks 111 of injection mold 100 from the application of excessive axial force when the mold halves Hl and H2 are closed and clamped together for inj ection molding. More specifically, the tonnage blocks 118 may provide a load path by which some of the clamping force may be transferred from the stripper plate 120 (described below) to the cavity plate 110 when the injection mold 100 is closed, as in FIG. 1. In the embodiment illustrated in FIG. 2, the tonnage blocks 118 are arranged in seven columns, to fit between the eight columns of cavity inserts 112 on the cavity plate 110 of this embodiment.

[0064] Referring to FIG. 3, the cavity plate assembly 102 further includes a plurality of gate inserts 116 — one per mold stack 111 — that are mounted at a rear face 113 of the cavity plate 110. Each gate insert 116 acts as an interface between a respective sprue of a melt distribution network (not depicted) and a respective cavity insert 112 of the cavity plate assembly 102. An example gate insert 116 is shown in FIGS. 6 and 7, described below.

[0065] FIG. 4 illustrates stripper plate assembly 104 of the injection mold 100 of FIG. 1 in isolation, in rear perspective view. As illustrated, the stripper plate assembly 104 includes a stripper plate 120 with a wear plate 122 attached to its rear face 123.

[0066] The stripper plate assembly 104 further includes eight pairs 124 of slides 124A, 124B slidably coupled to the stripper plate 120 adjacent to the wear plate 122. The slide pairs 124 are oriented substantially vertically in FIG. 4, with each slide pair 124 being aligned with a respective one of the eight columns of cavity inserts 112 of the adjacent cavity plate assembly 102 of FIGS. 2 and 3. Mounted to each slide pair 124 is a plurality of split mold insert pairs 126, each being a part of a respective mold stack 111. The first split mold insert 126A of each split mold insert pair 126 is mounted to a first slide 124A of the slide pair 124, and the second, complementary split mold insert 126B is mounted to the other slide 124B of the slide pair 124. This is done so that all of the split mold insert pairs 126 mounted to a single slide pair 124 can be caused to open and close in unison upon reciprocation of the slides 124A and 124B between a closed (molding) configuration and an open (molded article release) configuration.

[0067] The split mold inserts 126 A, 126B may be mounted to their respective slides 124A, 124B using fasteners, which may be removable, such as screws, bolts, or pins. The mounting is such that the split mold inserts 126 A, 126B are fixed relative to slides 124 A, 124B, respectively.

[0068] Referring to FIG. 4, each split mold insert 126A, 126B of a split mold insert pair 126 is movable along a split mold insert opening axis BB that is perpendicular to the mold opening axis AA. Each split mold insert pair 126 is reciprocable between the closed (molding) configuration shown in FIGS. 4 and 7 and an open configuration in which the split mold inserts 126A, 126B are separated from one another for molded article release.

[0069] The eight slides 124A of the stripper plate assembly 104 are interconnected by a set of connecting bars, forming a slide assembly for common lateral movement thereof. Similarly, the eight slides 124B of the stripper plate assembly 104 are separately interconnected by another set of connecting bars, forming another slide assembly for common lateral movement. The connecting bars are perpendicular to the slides. Each slide assembly is a separate structure that can be driven laterally as a unit independently of, and in an opposite direction to, the other slide assembly. The lateral driving force for each slide assembly may be provided by a respective camming mechanism upon movement of stripper plate assembly 104 relative to the core plate assembly 106 along the mold opening axis AA, as described below.

[0070] Referring to FIG. 5, the core plate assembly 106 of injection mold 100 is illustrated in isolation, in rear perspective view. The core plate assembly 106 includes a core plate 130 with a plurality of core inserts 132 — one per mold stack 111 — mounted thereto. The arrangement and spacing of the core inserts 132 on the core plate 130 matches that of the cavity inserts 112 on the cavity plate 110 (FIG. 2). Associated with each core insert 132 is a respective core ring 134 and a respective lock ring 136, as perhaps best seen in FIG. 7 (described below). The core ring 134 is a generally tubular component designed to fit over and cooperate with the core insert 132 to collectively define a top portion of a molding cavity for a preform. The lock ring 136 helps to anchor the cavity insert 112 to the core plate 130 and defines a female receptacle for a male projecting portion of the split mold insert pair 126, described below.

[0071] Referring to FIG. 6, an example mold stack 111 of injection mold 100 is depicted in axial cross-section. The mold stack 111 of FIG. 6 is in a closed (molding) configuration, as it appears when the mold halves Hl and H2 are closed and a clamping force has been applied to the injection mold 100, before melt injection has commenced. FIG. 7 shows the mold stack 111 of FIG. 6 in exploded view. The other mold stacks 111 of inj ection mold 100 may have a similar structure, although the mold stacks 111 described below in connection with FIGS. 21-16 are configured slightly differently as will be described. The structure the mold stack elements of FIG. 7 is generally consistent with the prior art.

[0072] Referring to FIG. 7, the mold stack 111 has a first mold stack portion 150 and a second mold stack portion 152 that are associated with the first mold half Hl and the second mold half H2, respectively, of injection mold 100. The first mold stack portion 150 includes a cavity insert 112, a cavity flange 114, and a gate insert 116. These elements form part of the cavity plate assembly 102 of FIGS. 2 and 3. The second mold stack portion 152 includes a split mold insert pair 126, a core insert 132, a core ring 134, and a lock ring 136. The split mold insert pair 126 is associated with the stripper plate assembly 104 of FIG. 4. The core insert 132, core ring 134, and lock ring 136 are each associated with the core plate assembly 106 of FIG. 5.

[0073] When in the closed configuration depicted in FIG. 6, the mold stack 111 defines a molding cavity 154 whose shape substantially corresponds to a final cold-state shape of the preform 160 shown in FIGS. 8 A and 8B, in perspective view and cross-section, respectively. Referring to FIGS. 8A and 8B, the example preform 160 has an elongate body 162, a hemispheric closed bottom 164, an open end 165, and a neck portion (or “neck finish”) 166. The neck portion 166 is an external surface region of the preform 160 that includes various external features in relief, including threads 168 for accepting and retaining a closure such as a threaded cap, an anti-pilfer bead 170, and a support ledge 171.

[0074] The split mold insert pair 126 is depicted in FIG. 7 in a closed (molding) configuration in which opposed mating faces (shutoff faces) of the complementary split mold inserts 126A, 126B are in contact with one another. The mating faces define a parting line 145 through the split mold insert pair 126 that is substantially parallel to the mold opening axis AA. In the closed configuration, the split mold inserts 126 A, 126B cooperate to define a molding surface 127 for molding the exterior surface of the neck portion 166 of the preform 160 of FIGS. 8 A and 8B.

[0075] The split mold insert pair 126 has a body portion 140, a first male projecting portion 142 projection from a rear (cavity) side of the body portion 140, and a second male projecting portion 144 projecting from a front (core) side of the body portion 140. Each of the male projecting portions 142, 144 of the present embodiment is a taper with a frustoconical shape. The body portion 140 of the present embodiment is a flange.

[0076] The parting line 145 passes through the body portion 140 and both male projecting portions 142, 144 and separates the split mold insert pair 126 into two parts, i.e., separates the split mold inserts 126A and 126B from one another. When the mold halves Hl and H2 of injection mold 100 are closed, the male projecting portion 142 is received within a corresponding female receptacle 172 defined within cavity flange 114, and the male projecting portion 144 is received within a corresponding female receptacle 174 defined within the lock ring 136 (see FIG. 6). In the present embodiment, the female receptacles 172, 174 are tapered seats having a complementary frustoconical shape to that of their corresponding tapered male projecting portions 142, 144 respectively. The shape of the female receptacles 172, 174 facilitates alignment and locking of the split mold insert pair 126 relative thereto and the holding together of the split mold inserts 126 A, 126B in the closed configuration when the mold halves Hl, H2 are closed. FIG. 9 is a close-up perspective view of part of the neck portion 166 of a preform 160 illustrating vertical flash 169. The flash 169 is referred to as “vertical flash” because it is oriented vertically (axially), along the neck portion 166 of the preform 1 0. Such vertical flash 169, which may be considered undesirable, can result if the split mold inserts 126A, 126B separate from one another too much during the melt injection or hold (packing) phase of an injection molding cycle. The present disclosure provides an approach for dynamically assessing a risk of such vertical flash during an injection molding cycle using a split mold insert movement detector, specifically a sensor 180 as shown in FIG. 6.

[0077] Referring to FIG. 6, the sensor 180 is configured to measure movement of a first one of the split mold inserts — specifically, split mold insert 126A in the present embodiment — along the split mold insert opening axis BB when the first and second mold halves Hl, H2 are closed. In the depicted embodiment, the sensor 180 is configured to indirectly measure the movement of the split mold insert 126A along the split mold insert opening axis by directly measuring movement of another mold component that is fixed relative to, and moves in lockstep with, the split mold insert 126A, namely, slide 124A. The sensor 180 is mounted to the tonnage block 118 adjacent to, and facing, the slide 124A.

[0078] In the depicted embodiment, the sensor 180 is an inductive linear position (distance) sensor, such as a Baumer™ IWFM 20I9501 / S35 sensor. The sensor 180 measures the distance to, or position of, an object and outputs an indicator of the movement, which may be an electronic signal indicative of the movement. In alternative embodiments, different types of sensors may be used, such as, for example, optical distance sensors. As will be described, the sensor 180 may be one of a plurality of such sensors 180 disposed within different ones of the plurality of mold stacks 111 of injection mold 100.

[0079] In some embodiments, the injection mold 100 of FIG. 1 may be part of an injection molding system having an associated human-machine interface. For example, FIG. 10 is a simplified schematic diagram of an injection molding system 200 including the injection mold 100 and human-machine interface (HMI) 202 communicatively coupled to, among other things, the sensor(s) 180 of the injection mold 100. Other elements of the injection molding system 200 have been omitted for brevity.

[0080] The human-machine interface 202 is a mechanism that allows a human operator to receive user notifications relating to the operation of the injection mold 100. The HMI 202 may include a display, such as a liquid crystal display (LCD), for presenting a graphical user interface (GUI), and a user input mechanism, such as a keyboard and / or pointing device (e.g., a touchscreen or mouse), for entering user input, none of which are expressly depicted in FIG. 10. In one aspect, the user notifications may include indications of a vertical flash risk for at least one molding cavity 154 of the injection mold 100, as will be described. The HMI 202 may also have other related functions, such as displaying an operational state of injection mold 100 and presenting user notifications regarding other aspects of molding machine operation, which are not depicted. The HMI 202 may be associated with a controller (not illustrated) that is responsible for controlling the operation of injection mold 100. The controller may for example issue machine control commands, including commands for actuating various components of the injection mold 100 in an actuation sequence (e.g., an injection molding sequence or cycle). The commands may be communicated from the controller to the injection mold 100 over a connection, which may for example be an electrical cable (e.g., a shielded Ethernet category 6A cable). The controller may also periodically or continuously receive, via the connection, machine state information indicative of the operational state of the injection mold 100, such as the current positions of various actuated machine components

[0081] Operation 300 of the injection molding system 200 for facilitating determination of vertical flash risk of the mold stack 111 of FIG. 6 is depicted in the flowchart of FIG. 11. Operation 300 may occur during any chosen molding cycle(s) of the injection mold 100 or, optionally, dunng every molding cycle. Operation 300 will be described in conjunction with FIGS. 12-19, which depict the example mold stack 111 of FIG. 6 in axial cross-section at various stages of a single inj ection molding cycle.

[0082] It is presumed that, at the commencement of operation 300, the first and second mold halves Hl, H2 of injection mold 100 have been closed in preparation for injection molding. FIG. 12 shows the mold stack 111 of FIG. 6 in cross-section just prior to mold closure.

[0083] Referring to FIG. 12, the stripper plate assembly 104 and core plate assembly 106 (along with platen 108, not depicted) are together moved rearwardly towards the stationary cavity plate assembly 102, with the movement being depicted using arrows in outline. The split mold inserts 126A, 126B and core insert 132 accordingly move rightwardly in FIG. 12, whereas the cavity plate 110, cavity insert 112, and cavity flange 114 are stationary. The male projecting portion 144 of split mold insert pair 126 is seated within the tapered female receptacle 174 defined by the lock ring 136. The slide 124A approaches and clears the sensor 180 as the mold halves Hl, H2 are closed.

[0084] Referring to FIG. 13, which shows the mold stack 111 of FIG. 12 later during mold closure, the tapered face 141 of the male projecting portion 142 of the split mold insert pair 126 has come into contact with the complementary tapered face 173 of the female receptacle 172 of the cavity flange 114. It will be appreciated that, when this contact is made: the shutoff face 113 of the cavity insert 112 and the shutoff face 143 of the male projecting portion 142 of the split mold insert pair 126 will not yet be in contact with one another but rather are separated by a gap Gl; the shutoff face 137 of the lock ring 136 is separated from the shutoff face 147 of the male projecting portion 144 by a gap G2; the slide pair 124A, 124B is separated from the wear plate 122 by a gap G3; and the core plate 130 is separated from the tonnage block 118 by a gap G4.

[0085] FIG. 14 depicts the mold stack 111 of FIG. 13 at a later time, when an initial clamping force has been applied to the injection mold 100 in the mold opening axis AA dimension. The clamping force may for example be hydraulically generated and may be applied by the platen 108 (FIG. 1). In FIG. 14, the amount of clamping force that is being applied may be substantially less than (e.g., 10% of) a maximum clamping force that will be applied later, during the melt injection and hold phases.

[0086] As shown in FIG. 14, the initial clamping force causes certain shutoff faces of the mold stack 111 to close. For example, the shutoff face 113 of the cavity insert 112 contacts the shutoff face 143 of the male projecting portion 142 of the split mold insert pair 126 (i.e., gap G1 becomes zero). Similarly, the shutoff face 137 of the lock ring 136 contacts the shutoff face 147 of the male projecting portion 144 (i.e., gap G2 also becomes zero). It will be appreciated that, in FIG. 14, the tapered face 141 of the male projecting portion 142 and / or complementary tapered face 173 of the female receptacle 172 of the cavity flange 114 (as shown in FIG. 13) have become axially preloaded.

[0087] In contrast, the initial clamping force applied in FIG. 14 is insufficient to eliminate (zero) the gap G3 between the slide pair 124A, 124B and the wear plate 122 or the gap G4 between the stripper plate 120 and the tonnage block 118. The initial clamping force does however reduce the extent of these gaps G3 and G4.

[0088] FIG. 15 depicts the mold stack 111 at a later time when the clamping force has reached its maximum. As illustrated, the clamping force has caused the mold stack 111 to become axially compressed (operation 302, FIG. 11), with the extent of each of gaps Gl, G2, G3, and G4 having been minimized (in this case, zeroed). The tonnage block 118 may, at this stage, bear part of the axial clamping force and thereby shield the mold stack 111 from excessive force that might otherwise result in mold stack damage.

[0089] While the mold stack 111 is axially compressed and before filling the molding cavity 154 with melt, a reference reading is taken from sensor 180 (operation 304, FIG. 11). In this example, the reference reading is a baseline position P0 of the slide 124A along split mold insert opening axis BB. In this example, the reference reading that is taken is a distance from the sensor 180 to slide 124A.

[0090] Pressurized melt 182 is then injected from a melt distribution device (not illustrated) into the molding cavity 154 via the gate insert 116, i.e., the molding cavity 154 of the mold stack 111 is filled with melt 182 (operation 306, FIG. 11). FIG. 16 depicts the mold stack 111 with operation 306 ongoing but not yet completed, i.e., with the melt 182 having only partially filled the molding cavity 154.

[0091] When the molding cavity 154 is mostly filled with melt 182 (e.g., 85% full), the melt distribution device may transition from a filling operation to a hold operation. During the hold operation, melt 182 may be injected into the molding cavity 154 at a lower speed and at a higher pressure than during the filling operation. The pressure of the melt 182 within the molding cavity 154 may be higher during the hold phase than at any other time of the molding cycle. The purpose of the hold operation may be to pack melt 182 into the molding cavity 154 to compensate for any shrinkage of the molded article that may result from melt hardening and cooling.

[0092] FIG. 17 depicts the mold stack 111 of FIG. 16 in cross-section at the time that the molding cavity 154 is filled with melt. During the hold operation, the high pressure of the melt 182 within the molding cavity 154 may cause a partial decompression of the mold stack 111 to occur. This phenomenon, which may be referred to as “mold breathing,” is illustrated in FIG. 18.

[0093] FIG. 18 depicts the mold stack 111 immediately after, or substantially contemporaneously with, the filling of the molding cavity 154. In FIG. 18, outward force from the highly pressurized melt 182 within the molding cavity 154 has partially opposed the clamping force that is being applied to the injection mold 100 along the mold opening axis AA. The result is a partial decompression of the mold stack 111 that has manifested in FIG. 18 in two ways. Firstly, the gap G3 between the slides 124A, 124B and the wear plate 122 has increased from zero to a positive value. Secondly, the gap G4 between the stripper plate 120 and the tonnage block 118 has also increased from zero to a positive value. Notably, the gaps G1 and G2 of the depicted example embodiment remain at zero, i.e., shutoff faces 113, 143 and 137, 147 remain in contact with one another. The reason may be that the amount of force required to fully compress the stack is greater than the amount required to overcome taper preload.

[0094] After the molding cavity 154 has been fdled and with the clamping force still being applied to the injection mold 100, movement of the split mold insert 126A along the split mold insert opening axis BB is measured by sensor 180 based on the reference reading P0 (operation 308, FIG. 11). This operation is illustrated in FIG. 19.

[0095] Referring to FIG. 19, which is a cross-section of the mold stack 111 of FIG. 18 at a later point in time, it can be seen that the body portion 140 of the split mold insert 126A has moved laterally outwardly (i.e., upwardly in FIG. 19). The inventor has concluded that this outward movement, in at least some embodiments, is likely due to a deformation or flexing of the split mold insert 126 A rather than a lateral translation of the split mold insert 126A. This is depicted in FIG. 20.

[0096] FIG. 20 is a simplified schematic depiction of a portion of the mold stack 111 of FIG. 19. The components depicted in FIG. 20 include the split mold insert pair 126, a portion of the slide 124 A, and the sensor 180. For clarity, these components are illustrated in simplified form from the perspective of the base 119 (see FIG. 19) of tonnage block 118.

[0097] As illustrated in FIG. 20, the parting line 145 between the split mold inserts 126 A, 126B is laterally outwardly bowed in the area of the body portion 140 of the split mold insert pair 126 (the bowing effect being simplified and exaggerated in FIG. 20 for comprehensibility and visibility). The opposed bowing may also create a lens-shaped gap in the molding surface 127 between shutoff (mating) faces of the two split mold inserts 126 A, 126B (not expressly depicted in FIG. 20), in a middle region of the molding surface 127, i.e., between male projecting portions 142 and 144.

[0098] The inventor has surmised that the outward bowing described above likely results from the high internal melt pressure applied outwardly upon the molding surface 127 of the split mold insert pair 126 at this stage of the injection molding cycle. The bowing constitutes a deformation of each of the split mold inserts 126A and 126B from its resting shape. The deformation may occur, at least in part, because the tapered female receptacles 172 and 174 “lock” together the complementary halves of male projecting portions 142 and 144, respectively, of the split mold inserts 126A, 126B, as depicted in FIG. 20 by the opposed pairs of arrows L. In contrast, the body portions 140 of each of the split mold inserts 126A, 126B are not so locked together. The internal melt pressure upon molding surface 127 is so great that the two halves of body portion 140 comprising split mold inserts 126A and 126B flex (bow) slightly away from one another.

[0099] In view of the above-described flexing of the split mold insert 126 A, the body portion 140 moves slightly outward laterally. This movement in turn pushes the slide 124A from its reference position P0 to a new position Pl (FIG. 19) along the split mold insert opening axis BB. The movement of the split mold insert 126A may accordingly be calculated as the difference between the baseline position P0 and the new position Pl.

[0100] For clarity, presuming that the split mold insert pair 126 is made from an elastically deformable material, such as a hardened stainless steel, the slight flexing (bowing) that is shown in FIG. 20 may be transient (i.e., non-permanent). After the hold phase is concluded and high internal melt pressure is no longer applied to the molding surface 127, the split mold inserts 126A and 126B may revert to their original, unbowed shape.

[0101] Referring again to FIG. 10, the human-machine interface 202 of injection molding system 200 may receive an indicator of the movement of the split mold insert 126 A from the sensor 180 as measured in operation 308 (FIG. 11). In some embodiments, the HMI 202 may dynamically provide a flash risk notification for mold stack 111 based upon that indicator, e g., as depicted in FIG. 27. The flash risk may for example be a function of (proportional to) the measured movement.

[0102] Referring to FIG. 27, an example HMI 202 is depicted. The depicted HMI 202 includes a gauge 400 for providing a flash risk notification to an operator. The gauge 400 includes a penannular scale 402 and a pointer 403, both of which may be graphically rendered elements on a display screen for example. The example scale 402 ranges from zero to a maximum value. In the present embodiment, the scale 402 is subdivided into three sections 404, 406, and 408, representing a low flash risk, medium flash risk, and high flash risk, respectively. Alternative embodiments may provide the flash risk notifications in other ways, e.g., using one or more alternative visual, auditory, and / or haptic indicators.

[0103] In the example gauge 400 of FIG. 27, the position of the pointer 403 within the first section 404 of scale 402 indicates a low flash risk. The position of the pointer 403 along the scale 402 may be based on the indicator received from sensor 180. In some embodiments, the flash risk value indicated by pointer 403 may be proportional to the degree of movement of the split mold insert 126A as measured in operation 308 (FIG. 11). In some embodiments, the flash risk may take into account a depth of a vent groove (not shown) that may be formed in a mating face of one the split mold inserts 126 A, 126B. For example, the vent groove depth may be added to the estimated gap size resulting from the measured movement of the split mold insert 126 A and an estimated movement of the other split mold insert 126B. The movement of the other split mold insert 126B may for example be estimated as being identical to the measured movement of the split mold insert 126 A.

[0104] In some embodiments, the limits of each of the sections 404, 406, and 408 of the scale 402 of FIG. 27 may be configurable, e.g., based on a degree of flash tolerance that may be application specific. In some embodiments, the limits of each of the sections 404, 406, and 408 may depend upon one or more injection molding parameters, such as a maximum pressure of the melt 182 within the molding cavity 154, an expected temperature of the melt 182 when the maximum pressure is being applied, and / or the type of molding material being used. In some embodiments, the flash risk thresholds between low, medium, and high risk indicators may be empirically determined, e.g., by force-flashing the injection mold 100 at various melt pressures and identifying a gap size above which a degree of flashing has become unacceptable for the relevant molded articles. The degree of unacceptable flashing may be specific to the article type and / or application.

[0105] In some embodiments, movement of the split mold insert 126A along the split mold insert opening axis BB may be measured directly versus indirectly as described above Such an embodiment is depicted in FIG. 21.

[0106] FIG. 21 is an axial cross-section of another mold stack 111 of injection mold 100. In many respects, the mold stack 111 is identical to the mold stack 111 of FIGS. 6 and 7 in terms of its structure and its constituent parts. Reference numerals in FIG. 21 are accordingly consistent with those of FIGS. 6 and 7.

[0107] The structure of FIG. 21 differs from that of FIG. 6 in the placement of sensor 180. In FIG. 21, the sensor 180 is configured to directly measure the movement of the first split mold insert 126A along the split mold insert opening axis BB. To that end, the sensor 180 is positioned on the tonnage block 118 at a point that is laterally adjacent to the body portion 140 of split mold insert 126A when the mold halves Hl, H2 are closed. It will be recalled that the body portion 140 is a region of the split mold insert 126A that is susceptible to flexing responsive to an application of melt pressure against molding surface 127. Susceptibility to outward flexing in this example results, at least in part, from the fact that the body portion 140 of the split mold insert 126A is not directly restrained from lateral movement, e.g., in the manner that male projecting portions 142 and 144 are restrained from lateral movement by tapered female receptacles 172 and 174 respectively. Thus, the sensor 180 is configured to directly measure the movement of the split mold insert 126A at the region of the split mold insert 126A that is susceptible to outward flexing. This may maximize an accuracy of the detected movement (deformation). A possible trade-off may be a more complicated installation of sensor 180 compared to the indirect measurement configuration of FIG. 6, in which the sensor 180 might be installable at any of multiple convenient locations along the length of slide 124A. Another possible trade-off of the embodiment of FIG. 21 may be that the sensor 180 may protrude further from tonnage block 118, e.g., compared to the partially recessed profile of sensor 180 on the tonnage block 118 of FIG. 6. The greater protrusion may increase a risk of damage to sensor 180 during mold operation.

[0108] FIG. 22 is a simplified schematic depiction of a portion of the mold stack 111 of FIG. 21 including the split mold insert pair 126 and the sensor 180 during a hold phase of the injection molding cycle. The conventions of FIG. 22 are similar to those of FIG. 20. The components depicted in FIG. 22 are in simplified form and are shown from the perspective of the base 119 of tonnage block 118 (FIG. 21).

[0109] Like in FIG. 20, the parting line 145 between the split mold inserts 126 A, 126B in FIG. 22 is laterally outwardly bowed in the area of the body portion 140 of the split mold insert pair 126 (the bowing effect being simplified and exaggerated in FIG. 22 for visibility). The bowing is indicative of a deformation of each of the split mold inserts 126A and 126B from their resting shape due to melt pressure against molding surface 127. As described in connection with FIG. 20, the deformation in FIG. 22 may occur, at least in part, because the tapered female receptacles 172 and 174 of the mold stack 111 “lock” together the complementary halves of male projecting portions 142 and 144, respectively, of the split mold inserts 126A and 126B, as depicted in FIG. 22 by the opposed pairs of arrows L. In contrast, the body portions 140 of each of the split mold inserts 126A, 126B are not so locked together. The melt pressure may accordingly cause each of the split mold inserts 126A, 126B to bow outwardly away from one another. The opposed bowing may undesirably create a lens-shaped gap in the molding surface 127 between mating faces of the two split mold inserts 126A, 126B (not expressly depicted in FIG. 20) in a middle region of the molding surface 127, i.e., between male projecting portions 142 and 144.

[0110] It will be appreciated that, due to the strength of the tonnage block 118 (in view of its purpose, as described above), the mounting of the sensor 180 to the tonnage block 118 in the above-described embodiments may advantageously protect the sensor 180 from damage. However, it is not mandatory for the sensor 180 to be mounted to a tonnage block 118.

[0111] For example, FIG. 23 is an axial cross-section of yet another mold stack 111 of injection mold 100 in which the sensor 180 is mounted to a bracket 185 rather than a tonnage block 118. In many respects, the mold stack 111 of FIG. 23 is identical to the mold stack 111 of FIG. 21 in terms of its structure and its constituent parts. Reference numerals in FIG. 23 are accordingly consistent with those of FIG. 21. An exception is that the mold stack 111 of FIG. 23 lacks an associate tonnage block 118. As in FIG. 21 , the sensor 180 of FIG. 23 is configured to directly measure the movement of the first split mold insert 126A along the split mold insert opening axis BB. The mounting position of sensor 180 on bracket 185 is laterally adjacent to the body portion 140 of split mold insert 126A, i . e. , adjacent to a region of the split mold insert 126A that is susceptible to outward flexing. A bracket 185 may for example be used in embodiments lacking tonnage blocks 118 or to customize an installation location to simplify electrical wire routing or for accessibility.

[0112] Regardless of whether the structure to which the sensor 180 is mounted is a bracket 185, a tonnage block 118, or otherwise, the structure to which the sensor 180 is mounted should be sufficiently stable minimize a risk of lateral movement of the sensor 180 relative to the cavity plate 110 during at least the phase of the melt injection cycle when melt pressure is at its peak.

[0113] In the above-described embodiments, the sensor 180 is mounted in fixed relation to the cavity plate 110, either to the tonnage block 118 or to another structure such as bracket 185. Mounting the sensor 180 in fixed relation to the cavity plate 110 may be advantageous in certain respects. For example, for injection molds in which the distance from the cavity plate to the split mold inserts is constant regardless of the molded articles being manufactured, mounting of the sensor 180 in fixed relation to the cavity plate 110 may permit the same sensor 180, in the same mounting position, to be used to monitor split mold insert movement regardless of which articles are being molded. Nevertheless, in alternative embodiments, the sensor 180 could be mounted in fixed relation to the core plate 130 rather than to the cavity plate 110. This is depicted in FIG. 24.

[0114] FIG. 24 is an axial cross-section of a further mold stack 111 of injection mold 100 in which the sensor 180 for detecting lateral movement of the split mold insert 126A is attached to a mount 190 that is in turn mounted to the core plate 130. In the depicted embodiment, the mount 190 is accommodated in a bore 192 through the stripper plate 120. In other respects, the mold stack 111 of FIG. 23 is similar to the mold stack 111 of FIG. 6 in terms of its structure and its constituent parts. Reference numerals in FIG. 24 are accordingly consistent with those of FIG. 6.

[0115] The sensor 180 is attached at a distal end of the mount 190 so as to be adjacent to a front portion of slide 124A when the mold halves Hl, H2 are closed. As in FIG. 6, the sensor 180 of FIG. 24 is configured to indirectly measure the movement of the first split mold insert 126A along the split mold insert opening axis BB by directly measuring the movement of the slide 124A to which the split mold insert 126A is mounted.

[0116] To limit a risk of damage to the sensor 180 from the lateral movement of the slide 124A during molded article stripping after the molded article has cooled, the sensor may be mounted laterally adjacently to a front-most (left-most in FIG. 24) part of the slide 124A. This placement of sensor 180 may allow the slide 124A to clear the sensor 180 during stripping of the preform 160 from the core insert 132.

[0117] More specifically, FIG. 24 depicts the trajectory T along which the slide 124A may travel during stripping of the preform 160. Initially, the slide 124A — along with its counterpart slide 124B, whose movement is not depicted in FIG. 24 — will move rearwardly along a straight segment T1 of the traj ectory T away from the core plate 130. During this movement, the split mold insert pair 126A, 126B mounted to the slides 124A, 124B will encapsulate the neck portion 166 of the freshly molded preform 160, thereby pulling preform 160 from the core insert 132. Subsequently, the slide 124A will follow the divergent segment T2 of the trajectory T, moving laterally away from its counterpart slide 124B as both slides 124A, 124B continue their rearward movement. In the result, the split mold inserts 126A, 126B will separate sufficiently to release the neck portion 166 and thus preform 160 from the injection mold 100.

[0118] For clarity, the two dashed partial outlines of slide 124A in FIG. 24 denote the future position of the slide 124A along the segment T2 of the trajectory T at two distinct points in time. For clarity, it will be appreciated that, because the mold halves Hl, H2 will have initially separated before the slide movement of FIG. 24 occurs, the slide 124A will not come into contact with the cavity plate 110 as it moves along segment T2 of trajectory T.

[0119] In the above-described embodiments, a single sensor 180 is used per mold stack 111 to measure a movement of only a first one of the split mold inserts 126A of a pair 126 for the purpose of assessing flash risk. In such embodiments, it may be reasonable to assume that the second, unmonitored split mold insert 126B will also move outwardly laterally to approximately the same extent as the monitored split mold insert 126 A. Nevertheless, it is possible that, in some embodiments, the split mold inserts 126A, 126B of a pair 126 may move to slightly different extents. Therefore, for maximum accuracy, it may be desirable to independently measure a movement of the second split mold insert 126B as well. This is depicted in FIGS. 25 and 26.

[0120] FIG. 25 is an axial cross-section of yet another mold stack 111 of injection mold 100 similar to that of FIG. 6 but having two sensors 180B, 180A, each configured to measure movement of a respective one of the split mold inserts 126A, 126B along the split mold insert opening axis BB. The first sensor 180A is mounted, like sensor 180 of FIG. 6, to a tonnage block 118 adjacent to the first split mold insert 126A. The second sensor 180B is mounted, in mirror image to sensor 180A, to a second tonnage block 118 on the opposite side of the mold stack 111 adjacent to the second split mold insert 126B. The structure and constituent parts of the mold stack 111 of FIG. 25 are otherwise similar to the mold stack 111 of FIG. 6. Reference numerals in FIG. 25 are accordingly consistent with those of FIG. 6.

[0121] Operation of the injection molding system 200 for facilitating calculation of vertical flash risk in the mold stack 111 of FIG. 25 may proceed as depicted in the flowchart of FIG. 11, with some additional steps. A clamping force may first be applied to the injection mold 100 to cause the mold stack 111 to become axially compressed, as shown in FIG. 25 (operation 302, FIG. 11).

[0122] While the mold stack 111 is axially compressed and before the molding cavity 154 is filled with melt, a reference reading is taken by the first sensor 180A (operation 304, FIG. 11). In this example, the reference reading is a baseline position P0A, along split mold insert opening axis BB, of the slide 124A to which the first split mold insert 126A is mounted. For example, the sensor 180A may measure the distance to slide 124A to be 10 microns.

[0123] In an added step analogous to operation 304, a reference reading is also taken by the second sensor 180B while the mold stack I ll is axially compressed and before the molding cavity 154 is filled with melt. In this case, the reference reading may be a baseline position P0B, along split mold insert opening axis BB, of the slide 124B to which the second split mold insert 126B is mounted.

[0124] The molding cavity 154 is then filled with pressurized melt 182 (operation 306, FIG. 11). For the reasons noted above in connection with FIGS. 17, 18, and 19, this causes a partial decompression of the mold stack 111 as well as an outward flexing of each of the split mold insert S126A, 126B, as shown in FIG. 26.

[0125] With the molding cavity 154 full of melt 182 and with the clamping force still being applied to the injection mold 100, movement of the split mold insert 126A along the split mold insert opening axis BB is measured by sensor 180A based on the reference reading P0A (operation 308, FIG. 11). The movement may be measured or calculated as P0A minus Pl A, where Pl A is the new position of the slide 124A shown in FIG. 26.

[0126] In an added step analogous to operation 308, the sensor 180B may measure, based on reference reading P0B, a movement of the second split mold insert 126B along the split mold insert opening axis that is opposed to the movement of split mold insert 126A. For example, in FIG. 26, the movement may be measured or calculated as P0B minus P1B, where P1B is the new position of the slide 124B shown in FIG. 26. It will be appreciated that a magnitude of this movement could conceivably from a magnitude of movement of split mold insert 126 A, although the difference may be relatively small. Finally, a flash risk notification may be provided on I 202. In this embodiment, the flash nsk may be based on a sum of the movement of each of split mold inserts 126A and 126B, i.e., the total gap between the mating faces of the split mold inserts 126A and 126B. More generally, the flash risk notification may be based upon the measured movement of both of the split mold inserts 126A and 126B.

[0127] Notably, merely doubling either one of the respective movements of either one of the split mold insert 126A or 126B, e.g., based on a presumption that each split mold insert 126A, 126B should move by the same amount, would have provided a less accurate indication of the total size of the gap between the split mold inserts 126A, 126B in the case where the split mold inserts 126A, 126B move by different amounts. Therefore, although not strictly required, the use of two sensors 180A, 180B as described may provide more accurate measurements, which may improve an accuracy of any flash risk notification that may be provided.

[0128] In each of the above-described example mold stack embodiments, the split mold insert pair 126 has two male projecting portions 142, 144 projecting in opposite directions, which can be used to lock the split mold inserts 126A, 126B together using complementary female receptacles 172, 174 respectively, as described above. It will be appreciated that, in alternative “cavity lock” embodiments, the split mold insert pair may have only a male projecting portion 142 on the cavity side without any male projecting portion 144 on the core side. In such embodiments, movement (including deformation) of either one or both of the split mold inserts 126 A, 126B of the split mold insert pair may be monitored as described above to assess vertical flash risk, either indirectly (e.g., as in FIGS. 19, 24, or 25) or directly (e.g., as in FIGS. 21 or 23).

[0129] It will be appreciated that the above-described method for determining vertical flash risk based on a measured degree of movement of the split mold insert 126A away from its counterpart split mold insert 126B may be reliable regardless of an extent of mold stack decompression or “mold breathing” that may occur within the relevant mold stack 111. The reason is that vertical flash risk is determined based on a measured deformation (or, more generally, movement) of the very component whose deformation (movement) can produce a gap between the split mold inserts 126A, 126B, which gap is precisely where vertical flash occurs. The method is also adaptive. Over time, factors such as taper wear may result in changes to (increases in) lateral split mold insert movement during the hold phase, which may increase a risk of vertical flash. These changes will be dynamically detected by the sensor 180, and the dynamically determined vertical flash risk will change accordingly.

[0130] The inventor considers that the extent of mold stack decompression that may occur during the hold phase (FIG. 18) may vary between mold stacks 111 and / or between different instances of the same injection mold. This may be due to many factors, such as tolerance stackups along the mold opening axis AA, variations in mold stack stiffness (e.g., mold stacks for producing longer molded articles may be “springier” than mold stacks for producing shorter molded articles), taper wear over time, uneven clamping force distribution across the injection mold 100 (e.g., due to deformation of platen 108), misalignment between the mold halves Hl and H2, and / or clamping force path variations across the injection mold 100. If view of these complex and possibly conflicting factors, the degree of mold stack decompression and / or mold breathing may, in some cases, be only loosely correlated with a risk of vertical flash.

[0131] It will further be appreciated that the method of vertical flash risk determination described herein will not only detect an elastic deformation of at least a first split mold insert 126A during the hold phase, but also an outward lateral translation of the split mold insert 126A during the hold phase. With taper wear over time, the risk of such outward lateral translation may increase over time. Advantageously, the vertical flash risk determination method described herein may reliably determine flash risk regardless of whether its cause is elastic deformation of the split mold insert 126A, lateral translation thereof, or a combination of these factors.

[0132] Other alternative embodiments are contemplated.

[0133] It will be appreciated that, in alternative embodiments, the molded article may be something other than a preform. In alternative embodiments, the split mold insert pair may define a molding surface for molding some other external surface region of a molded article besides a neck finish of a preform.

[0134] In at least some embodiments described above, a measured movement of a split mold insert may form a basis for a flash risk notification that may be provided to an operator, e.g., via a human-machine interface. It will be appreciated that such provision of a flash risk notification is not necessarily required in all embodiments. For example, some molding system and / or injection mold embodiments may be configured to take remedial action based on a measured movement of a split mold insert, such as causing a batch of molded preforms (or other molded articles) to be identified or treated as possibly being “out of specification” when excessive split mold insert movement has been detected.

[0135] Other modifications may be made within the scope of the following claims.

Claims

WHAT IS CLAIMED IS:

1. An injection mold (100), comprising: a mold stack (111) including a cavity insert (112), a core insert (132), and a split mold insert pair (126), the split mold insert pair defining a molding surface (127) for molding an external surface region (166) of a molded article (160); a first mold half (Hl) including a cavity plate (110) to which the cavity insert is mounted; a second mold half (H2) including a core plate (130) to which the core insert is mounted; the first mold half and the second mold half being configured to be opened and closed along a mold opening axis (AA); the split mold insert pair of each mold stack including a first split mold insert (126A) and a second split mold insert (126B) that are separable from one another, along a split mold insert opening axis (BB) that is perpendicular to the mold opening axis, when the first and second mold halves are open; and a sensor (180, 180A) configured to, when the first and second mold halves are closed, measure a movement, along the split mold insert opening axis, of the first split mold insert.

2. The injection mold of claim 1 wherein the sensor is configured to directly measure the movement of the first split mold insert along the split mold insert opening axis.

3. The injection mold of claim 2 wherein the first split mold insert is elastically deformable, wherein the movement is an elastic deformation of the first split mold insert, and wherein the sensor is configured to directly measure the elastic deformation of the first split mold insert along the split mold insert opening axis at a region of the first split mold insert that is susceptible to outward flexing responsive to an application of melt pressure against the molding surface during a molding cycle of the injection mold.

4. The injection mold of any one of claims 1 to 3 wherein the split mold insert pair comprises a body portion (140) and a male projecting portion (142) projecting from the body portion, wherein the first and second split mold inserts have respective mating faces that define a parting line (145) through both of the body portion and the male projecting portion of the split mold insert pair, wherein the mold stack further includes a component (114) defining a female receptacle (172) configured to receive and hold together the male projecting portion of the split mold insert pair when the first and second mold halves are closed, and wherein the sensor is configured to measure the movement of the first split mold insert at the body portion of the first split mold insert.

5. The injection mold of claim 1 further comprising a mold component in fixed relation to the first split mold insert, and wherein the sensor is configured to indirectly measure the movement of the first split mold insert along the split mold insert opening axis by directly measuring a movement of the mold component along the split mold insert opening axis.

6. The injection mold of claim 5 wherein the mold component in fixed relation to the first split mold insert is a slide (124A) to which the first split mold insert is mounted and wherein the sensor is configured to directly measure the movement of the slide when the first and second mold halves are closed.

7. The injection mold of any one of claims 1 to 6 wherein the sensor is mounted in fixed relation to the cavity plate.

8. The injection mold of claim 7 further comprising a tonnage block (118), mounted to the cavity plate, that is configured to bear at least part of a clamping force upon the injection mold when the first and second mold halves are closed, wherein the sensor is mounted to the tonnage block.

9. The injection mold of any one of claims 1 to 6 wherein the sensor is mounted in fixed relation to the core plate.

10. The injection mold of claim 9 further comprising a bracket (185) mounted to the core plate, wherein the sensor is mounted to the bracket.

11. The injection mold of any one of claims 1 to 10 wherein the sensor is an inductive linear position sensor.

12. The injection mold of claim 1 wherein the sensor is a first sensor, wherein the movement along the split mold insert opening axis is movement in a first direction, and further comprising a second sensor (180B) configured to, when the first and second mold halves are closed, measure a movement, along the split mold insert opening axis, of a second split mold insert (126B) of the split mold insert pair in a second direction opposed to the first direction.

13. The injection mold of claim 12 wherein the second sensor is configured to directly measure the movement of the second split mold insert along the split mold insert opening axis.

14. The injection mold of claim 13 wherein the second split mold insert is elastically deformable, wherein the movement is an elastic deformation of the second split mold insert, and wherein the second sensor is configured to directly measure the elastic deformation of the second split mold insert along the split mold insert opening axis at a region of the second split mold insert that is susceptible to outward flexing responsive to an application of melt pressure against the molding surface during a molding cycle of the injection mold.

15. The injection mold of claim 12 further comprising a mold component in fixed relation to the second split mold insert, and wherein the second sensor is configured to indirectly measure the movement of the second split mold insert along the split mold insert opening axis by directly measuring a movement of the mold component along the split mold insert opening axis.

16. The injection mold of claim 15 wherein the mold component in fixed relation to the second split mold insert is a slide (124B) to which the second split mold insert is mounted and wherein the second sensor is configured to directly measure the movement of the slide when the first and second mold halves are closed.

17. A method (300), comprising: applying (302) a clamping force to an injection mold (100), the clamping force causing a mold stack (111) of the injection mold to become axially compressed; while the mold stack is axially compressed and before filling a molding cavity (154) of the mold stack with melt (182), taking (304) a reference reading from a sensor (180, 180A) configured to measure movement of a split mold insert (126A) of the mold stack along a split mold insert opening axis (BB); filling (306) the molding cavity of the mold stack with melt; and after the filling and before removing the clamping force from the injection mold, measuring (308), by the sensor and based on the reference reading, a movement of the split mold insert along the split mold insert opening axis.

18. The method of claim 17 further comprising providing (310) a flash risk notification based, at least in part, upon the measured movement of the split mold insert.

19. The method of claim 17 wherein the sensor is a first sensor, wherein the reference reading is a first reference reading, wherein the movement along the split mold insert opening axis is movement in a first direction, wherein the split mold insert is a first split mold insert of a split mold insert pair (126) of the mold stack, and further comprising: while the mold stack is axially compressed and before the filling of the molding cavity of the mold stack with melt, taking a second reference reading from a second sensor (180B) configured to measure movement of a second split mold insert (126B) of the split mold insert pair along the split mold insert opening axis; and after the filling and before removing the clamping force from the injection mold, measuring, by the second sensor and based on the second reference reading, a movement, along the split mold insert opening axis, of the second split mold insert in a second direction opposed to the first direction.

20. The method of claim 19 further comprising providing a flash risk notification based, at least in part, upon the measured movement of the first split mold insert and the measured movement of the second split mold insert.

21. An injection molding system (200), comprising: an injection mold (100) including: a mold stack (111) including a cavity insert (112), a core insert (132), and a split mold insert pair (126), the split mold insert pair defining a molding surface (127) for molding an external surface region (166) of a molded article (160); a first mold half (Hl) including a cavity plate (110) to which the cavity insert is mounted; a second mold half (H2) including a core plate (130) to which the core insert is mounted; the first mold half and the second mold half being configured to be opened and closed along a mold opening axis (AA); the split mold insert pair of each mold stack including a first split mold insert (126A) and a second split mold insert (126B) that are separable from one another, along a split mold insert opening axis (BB) that is perpendicular to the mold opening axis, when the first and second mold halves are open; and a sensor (180, 180A) configured to, when the first and second mold halves are closed, measure a movement, along the split mold insert opening axis, of the first split mold insert and to output an indicator of the movement; anda human-machine interface ‘HMI’ (202) communicatively coupled to the sensor, the HMI being operable to, based on the indicator of the movement output by the sensor, dynamically provide a flash risk notification.

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