WO2009111854A1

WO2009111854A1 - In-mold closing mechanism and method

Info

Publication number: WO2009111854A1
Application number: PCT/CA2008/000485
Authority: WO
Inventors: Ealias C. Joseph
Original assignee: Stack Teck Systems Limited
Priority date: 2008-03-12
Filing date: 2008-03-12
Publication date: 2009-09-17

Abstract

An in-mold closing mechanism is provided for a molding apparatus which produces a molded part having a lid hingedly attached thereto and rotatable about a hinge axis between an initial open configuration adjacent the part and a closed configuration covering an opening in the molded part and lockingly engaging the molded part. The mechanism includes a base to which a rotator arm is mounted at a base end of the rotator arm. The rotator arm is rotatable about an arm axis parallel to the hinge axis. A lid engaging arm is attached to the rotator arm opposite the base end and configured to engage the lid for moving the lid toward its closed configuration. A translator is connected to the base to move the base and in turn the rotator arm between a deployed position wherein the lid engaging arm can engage the lid and a non-deployed position, clear of the lid to allow closure of the molding apparatus. A rotator is connected to the rotator arm for rotating the arm about the arm axis.

Description

IN-MOLD CLOSING MECHANISM AND METHOD

Field of the Invention

[0001] This invention relates generally to the field of plastics injection molding. More particularly, this invention relates to the closing of lids on injection molded parts before completely ejecting parts from a mold.

Background of the Invention

[0002] "Flip-top" closures are typically molded in an open configuration wherein a part and its lid are molded side by side, joined by a flexible or "living" hinge.

[0003] It is preferable that the lid be secured over a corresponding opening in the part as soon as possible after molding. One reason for this is that interlocking and sealing components on the part and its lid tend to mate better if allowed to cool together. Another reason is to avoid damage to the part during packaging and shipping. Yet another reason is that automated equipment for placing the part, which is typically a closure, over a container opening requires that the part be closed.

[0004] Previous in-mold closing arrangements have been relatively slow in action, limited to one to two rows of molded parts and obstructed the operator side of a molding machine. Previous in-mold closing arrangements have also tended to be heavy, imposing vibration and overhang weight problems on moving stripper plates.

[0005] It is an object of the present invention to provide an in-mold closing mechanism which overcomes at least some of the problems inherent in previous designs.

Summary of the Invention

[0006] A method for in-mold closing of a hinged lid molded in an injection mold integrally with but adjacent to a part, said method comprising the steps of: (i) at least partially stripping said part and said lid from said mold to provide a space between said mold and said lid;

(ii) advancing a lid engaging arm into said space;

(iii) rotating said lid engaging arm through an arc to cause said lid engaging arm to urge said lid over said part to close said lid.

[0007] Preferably the arc is about an axis axially aligned with an axis of the hinge.

[0008] The lid engaging arm may be configured to simultaneously engage a plurality of lids set out in a row.

[0009] A plurality of the lid engaging arms may be employed and simultaneously actuate to simultaneously engage a plurality of the rows of lids.

[0010] An in-mold closing mechanism is provided for a molding apparatus which produces a molded part having a lid hingedly attached thereto and rotatable about a hinge axis between an initial open configuration adjacent the part and a closed configuration covering an opening in the molded part and lockingly engaging the molded part. The mechanism includes a base to which a rotator arm is mounted at a base end of the rotator arm. The rotator arm is rotatable about an arm axis parallel to the hinge axis. A lid engaging arm is attached to the rotator arm opposite the base end and configured to engage the Hd for moving the lid toward its closed configuration. A translator is connected to the base to move the base and in turn the rotator arm between a deployed position wherein the lid engaging arm can engage the lid and a non- deployed position, clear of the lid to allow closure of the molding apparatus. A rotator is connected to the rotator arm for rotating the arm about the arm axis.

[0011] The closing arm axis preferably substantially aligns with the hinge axis in the deployed position. [0012] The rotator may comprise a toothed rack connected to a telescopic actuator for reciprocal movement thereby and pinion teeth attached to the rotator arm and meshing with the toothed rack to cause the rotator arm to rotate about the arm axis in response to reciprocal movement of the rack.

[0013] The rack may be slidably mounted on a rail which forms part of the translator.

[0014] The actuator may be a first fluid pressure actuated piston and cylinder arrangement connected to act between the rack and the translator. The translator may comprise a second fluid pressure response of piston and cylinder arrangement acting between the rail and the molding apparatus.

[0015] The closing arm may extend between at least two of the rotator arms and service a plurality of lids.

[0016] The closing mechanism may have a plurality of rails with a plurality of the mechanisms mounted in rows thereon to service a molding apparatus having a multi-cavity mold which forms a plurality of lids simultaneously in a plurality of rows and columns.

[0017] The part may be a container closure.

Description of Drawings

[0018] Preferred embodiments of the present invention are described below with reference to the accompanying illustrations in which:

[0019] Figure 1 is a front elevation of a multi-cavity cavity part of an injection molding mold incorporating an in-mold closing apparatus according to the present invention;

[0020] Figure IA is a view corresponding to figure 1 but showing the in-mold closing apparatus on its own;

[0021] Figure 2 is a section through line B-B of Figure 1 illustrating part of a closing mechanism according to the present invention; [0022] Figure 3 is a section through line C-C of Figure 1 ;

[0023] Figure 4 is a side view of an in-mold closing mechanism according to the present invention in a mold open position;

[0024] Figure 5 is a view corresponding to Figure 4 but showing the mechanism after rail movement;

[0025] Figure 6 corresponds to Figures 4 and 5 but showing movement of a closing arm on the mechanism during closing;

[0026] Figure 7 is a section on line A-A of Figure 1 illustrating the mold in a closed configuration with a mold closing mechanism according to the present invention in the non-deployed position;

[0027] Figure 8 corresponds to Figure 7 but illustrates the mold in an open configuration with first stage ejection complete and the in-mold closing mechanism actuated;

[0028] Figure 9 corresponds to Figures 7 and 8 and illustrates the in- mold closing mechanism returned to its non-deployed position with a second stage of ejection complete.

Description of Preferred Embodiments

[0029] An in-mold closing mechanism according to the present invention is generally indicated by reference 20 in the accompanying illustrations. The in-mold closing mechanism 20 is shown in Figure 1 within the context of a core part 30 of an injection molding apparatus (reference 60 in Figure 7) having a plurality of mold cores 32 arranged in rows and columns and surrounded by a stripper plate 34.

[0030] As illustrated in Figures 8 and 9 each core 32 partially defines a part 40, which has a lid 42 hingedly attached to it for rotation about a respective hinge axis 44.

[0031 ] The balance of the part is defined by a mold cavity 52 which, as illustrated in Figure 7 is on a cavity part 50 of the molding apparatus. The mold core 32 aligns with the mold cavity 52 to define the part 40 therebetween.

[0032] The core 32 is in three parts, an inner part 36 and an outer part

38 and a middle sleeve 37. The inner part 36 and outer part 38 are telescopic relative to the middle sleeve 37. This configuration enables the formation of a depending skirt 46 within the part 40 extending about an inwardly depending wall 48 defining a passage or opening 49 through the part 40. The skirt 46 and wall 48 are respectively defined, during molding, between the middle sleeve 37, outer part 38 and the inner part 36 of the core 32.

[0033] Figure 7 illustrates the molding apparatus 60 in a mold closed configuration. Figures 8 and 9 illustrate respectively first and second stages of part ejection in a mold open configuration. In the first stage of ejection, the stripper plate 34 and middle sleeve 37 of the mold core 32 are simultaneously moved, upward as illustrated (laterally as it would be installed in most molding machines) to lift the part 40 out of and away from the outer part 38 and inner part 36. In the second stage, the stripper plate 34 continues to move upwardly to lift the molded part 40 off of the middle sleeve 37 of the mold core 32. This completes ejection.

[0034] As mentioned above, the part 40 has a Hd 42 hingedly attached to it. When the part 40 is molded, the lid 42 is in an open configuration as illustrated in Figures 7 and 8. The lid is movable about the hinge axis 44 to a closed configuration illustrated in Figure 9. In the closed configuration the lid 42 extends over the opening 49. A protuberance 47 extending from an inside face of the lid 42 is received in the opening 49 to releasably engage the wall 48 extending thereabout in a locking and sealing manner. The protuberance has a lip 45 extending outwardly thereabout to effect the locking/sealing engagement. The protuberance 47 may not be present in some lid designs and is not necessary for operation of the in-mold closing mechanism 20.

[0035] As mentioned in the background, it is desirable for a variety of reasons to move the lid 42 to its closed configuration (i.e. to "close the lid") as soon as reasonably possible after forming and before the part 40 has fully cooled. It is believed that the parts mate better if they cool together. The in- mold closing mechanism 20 of the present invention, as described in detail below, closes the lid 42 before the part 40 is fully ejected from the mold. The mechanism 20 has a base 70 slidably mounted to an elongate rail 74. The rail 74 is in turn rigidly mounted to the ejector plate 34.

[0036] Extending upwardly from the base 70 and spaced apart along its length are pinion housings 72. The pinion housings 72 support a rotatable shaft 80. To rotatable shaft 80 are mounted, for co-rotation therewith, a rotator arm 90 and a pinion 100. The mounting may be by any suitable means including, without limitation, keying, splines or being machined as an integral assembly.

[0037] The rotator arm 90 attaches to the shaft 80 at a base end 92 and rotates about an arm axis 94 which coincides with the axis of the shaft 80. It should be borne in mind that this is but one mounting arrangement. Alternatives may be apparent to persons of ordinary skill in mechanical structures. For example, while the rotator arm 90 and pinion 100 are shown in the illustrations as being rigidly secured to the shaft 80, as an alternative the rotator arm 90 and pinion 100 may be rotatable about the shaft 80 and rotationally coupled to each other by means other than the shaft 80, such as for example, by being co-machined or having mating dogs and recesses.

[0038] The rotator arm 90 has a lid engaging arm 110 attached to it opposite its base end 92. The lid engaging arm 110 is shaped or configured in such a way as to engage the lid 42, when the mechanism 20 is in a deployed position as discussed in more detail below. Depending on the number of parts 40 being simultaneously molded, a single lid engaging arm 110 may service a single lid 42 or a row of lids 42. In the latter case, and as illustrated in Figure 1, a plurality of lid engaging arms 110 may be used, each extending between and carried by a pair of rotator arms 90 and servicing all or part of a row of lids.

[0039] During molding the Hd engaging arms are accommodated in recesses 102 in the mold cavity 32 so as not to interfere with mold closing and part molding. Once the mold is opened, the stripper plate 34 advances in a machine direction (up as illustrated in Figures 7-9) away from the cores 32. The mechanism 20 advances with the stripper plate 34 by virtue of being mounted thereon. This initial movement, or first stage of ejection, lifts the lid engaging arm(s) 110 out of the recesses 102.

[0040] A first hydraulic cylinder 120 is mounted to act between the stripper plate 34 and the base 70 to move the base 70 to the left and right as illustrated in Figures 1, 4-9. In this manner the first hydraulic cylinder 120 acts as a "translator" by causing translation or movement of the base along the rails 74 mounted to the stripper plate 34. Other translator means might be apparent to persons of relevant skill such as cam and follower, screw drives or crank arrangements.

[0041 ] After the first stage of ejection, as illustrated in Figure 8, the lid

42 is spaced apart from the cavity. The base 70 is then moved to the left as illustrated for the lid engaging arm 110 to move from an initial, non-deployed position (to the right) to a deployed position under the lid 42 (to the left). The rotator arm 90 is then caused to rotate, in a manner described in more detail below, to cause the lid engaging arm 110 to travel in an arc anti-clockwise (as illustrated). As shown in Figure 8, this causes the lid engaging arm 110 to urge the lid 42 from its open to its closed configuration.

[0042] A rotator in the form of pinion 100 and a rack 112 which meshes therewith is used to rotate the rotator arm 90. Other mechanisms might be substitutable therefor however the rack and pinion arrangement is sturdy, compact and robust.

[0043] In order to rotate the pinion 100, the rack 112 is advanced along the base 72. Movement of the rack 112 may be effected by a second hydraulic cylinder 130 acting between the rack 112 and the base 70. Other solutions might be feasible for moving the rack 112 such as perhaps a screw arrangement or a pneumatic cylinder.

[0044] As illustrated in Figure 1, a plurality of racks 112 may be connected to a common rack connecting member 114 for simultaneous movement by the second hydraulic cylinder 130. Similarly a plurality of bases may be connected to a common base connecting member 116 for simultaneous movement by the first cylinder 120.

[0045] Preferably the arm axis 94 will align axially with the hinge axis

44 of the lid 42 in the deployed configuration. While this may not be entirely necessary it should avoid the lid engaging arms 110 dragging along and scratching the lids 42 during closing. Rollers 140 may be provided about the lid engaging arm 110 to further cushion closing. The rollers 140 may for example be of polyurethane or other suitable material.

[0046] After closing, and as illustrated in Figure 9, the mechanism 20 is returned to its non-deployed configuration for the second and final ejection stage.

[0047] The above invention is described in an illustrative rather than a restrictive sense. Variations may be apparent to persons skilled in such arrangements without departing from the spirit and scope of the invention as defined by the claims set out below.

Claims

in-mold closing mechanism for a molding apparatus which produces a molded part having a lid hingedly attached thereto and rotatable about a hinge axis between an initial open configuration adjacent the part and a closed configuration covering an opening in said molded part and lockingly engaging said molded part, said mechanism comprising:

a base,

a rotator arm mounted at a base end to said base for rotation about an arm axis parallel to said hinge axis,

a lid engaging arm attached to opposite said rotator arm said base end configured to engage said lid when said rotator arm is in a deployed position for moving said lid toward said closed configuration;

a translator connected to said base for moving said base and in turn said rotator arm between said deployed position wherein said lid engaging arm can engage said lid and a non-deployed position clear of said lid to allow closure of said molding apparatus; and

a rotator connected to said rotator arm for rotating said arm.

2. The in-mold closing mechanism of claim 1 wherein said arm axis substantially aligns with said hinge axis in said deployed position.

3. The in-mold closing mechanism of claim 2 wherein said rotator comprises a toothed rack connected to a telescopic actuator for reciprocal movement thereby and pinion teeth attached to said rotator arm and meshing with said toothed rack to cause said rotator arm to rotate about said arm axis in response to said reciprocal movement of said rack.

4. The in-mold closing mechanism of claim 3 wherein said rack is slidably mounted on said base.

5. The in-mold closing mechanism of claim 4 wherein:

said actuator is a first fluid pressure actuated piston and cylinder arrangement connected to act between said rack and said base; and,

said translator further comprises a second fluid pressure responsive piston and cylinder arrangement acting between said base and said rail.

6. The in-mold closing mechanism of claim 5 wherein said closing arm extends between at least two of said rotator arms and services a plurality of lids.

7. The in-mold closing mechanism of claim 6 further comprising a plurality of said rails with a plurality of said mechanisms mounted in rows thereon to service a said molding apparatus having a multi-cavity mold forming a plurality of said lids simultaneously in a plurality of rows and columns.

8. The in-mold closing mechanism of claim 7 wherein said part is a container closure.

9. The in-mold closing apparatus of claim 7 wherein said mechanism is mounted on a stripper plate of said molding apparatus and is advanced in a machine direction along with said stripper plate prior to movement transverse to said machine direction in moving between said deployed and non-deployed configurations.

10. A method for in-mold closing of a hinged lid integrally molded in an injection mold with but adjacent to a part, said method comprising the steps of:

(i) at least partially stripping said part and said lid from said mold to provide a space between said mold and said lid;

(ii) advancing a lid engaging arm into said space; (iii) rotating said lid engaging arm through an arc to cause said lid engaging arm to urge said lid over said part to close said lid.

11. The method of claim 10 wherein said arc is about an axis axially aligned with an axis of said hinge.

12. The method of claim 11 wherein said lid engaging arm simultaneously engages a plurality of said lids set out in a row.

13. The method of claim 12 wherein a plurality of said lid engaging arms are employed and simultaneously actuated to simultaneously engage a plurality of said row of lids.