MXPA01004204A - Form keys and method for thermoforming undercuts in foam parts form keys and method for thermoforming undercuts in foam parts - Google Patents

Abstract

A pair of form keys and a method for forming reverse drafts in foam parts are disclosed. A male form key is reciprocally mounted in a first mold half in a retracted position. A female form key is rotatably mounted in a second mold half in a neutral position. The first mold half includes a first drive pin that when engaged, moves the male form key into engagement with a foam sheet to form an undercut as the first and second mold halves are closed. The first mold half also includes a second drive pin that engages the female form key as the first and second mold halves close rotating the female form key into engagement with the foam sheet and the male form key. After closure of the mold and the product is formed, the mold is opened. As this occurs, the drive pins are disengaged and the male form key retracts and the female form key rotates to their neutral positions. The formed product may then be stripped from the mold while maintaining the reverse draft or undercut

Description

FORMING CANDS AND METHOD FOR THERMOFORMING LESS MUESCASES DAMAGED IN FOAM PARTS FIELD OF THE INVENTION The present invention relates, in general, to forming wedges and to a method for using forming wedges, for thermoforming lower notches tapering into molded, coupled foam portions. More particularly, the invention relates to forming wedges, for forming an inverted taper into thermoformed portions, and to a method for thermoforming tapered lower notches, in portions, using coupled metal molds and for demolding the part of the molds, while maintaining the molds. lower tapering notches.

BACKGROUND OF THE INVENTION Foam containers, for restaurants, schools, hospitals and the like, are typically formed by placing a foam sheet between a pair of molds and closing the molds to thermoform a part. If the part requires, for example, a latch for a container with hinged lid, an inverted taper or tapered bottom notch may be formed, but, formed by an inverted taper or tapered bottom notch, for a secure in the part, particularly in foam parts, has been a problem. It has been difficult to form an inverted taper in foam containers, such as polystyrene foam containers, due to the inability to demold the formed part of the tool, while maintaining the desired shape of the inverted taper. For this reason a continuous thermoforming process to form parts with an inverted taper has not been possible. If this problem could be overcome, this would allow different designs of closures in the parts, and the development of continuous thermoforming processes to form foam parts.

SUMMARY OF THE INVENTION The present invention is directed to forming wedges to form an inverted taper in a thermoformed portion, for example, a part of polystyrene foam such as a container with hinged lid, and a method for thermoforming an inverted taper or tapered bottom notch, in the part, and unmolding the part of a mold, while maintaining the shape of an inverted taper or tapered bottom notch. The forming wedge is part of a mold used for thermoforming the foam parts. The mold includes two halves, a first half with a forming cavity, and a second half with a forming plug. A male shaped wedge is mounted, reciprocally, in the first half of the mold and moves reciprocatingly in and out of the forming cavity, in response to engagement with a first actuator bolt which is mounted, so that it can perform an alternate movement, in the first half of the mold and moves through the coupling with the second half of the mold. A female shaped wedge is rotatably mounted in the second half of the mold and is rotated between a first and a second position by engaging a second actuator bolt mounted on the first half of the mold. The method for thermoforming foam parts includes placing a sheet of foam between a forming cavity mold and a forming plug mold, each of which includes a wedge-shaped wedge or the female-shaped wedge, as described above. . Prior to thermoforming, the male forming wedge is biased to a retracted position outside a cavity and the female shaped wedge is biased to a non-engaging position. The forming cavity mold and the forming plug mold are subsequently joined. When this occurs, the male forming wedge and the female mold wedge move towards the foam sheet, forming a tapered lower notch or inverted taper, in a portion formed from the foam sheet. The forming cavity mold and the forming plug mold are subsequently separated. When this occurs, the male formed wedge and the female formed wedge are removed from the formed part and the formed part can be demoulded from the forming cavity and plug molds, while keeping the lower tapered groove. Although the present invention is focused on coupled metal molds and the thermoforming of foam parts, the invention can be applied to non-coupled metal molds and to the forming of parts from solid sheets.

BRIEF DESCRIPTION OF THE DRAWINGS Other objects and advantages of the invention will become apparent upon reading the following detailed descriptions and with reference to the drawings, in which: Figure 1 is an enlarged cross-sectional view of a thermoformed part including an inverted taper or lower notch tapered, formed in accordance with the principles of the present invention; Figure 2 is a cross-sectional view of a mold in an open position and used to mold the formed part illustrated in Figure 1; Figure 3 is an enlarged, cross-sectional view of a portion of the mold in the closed position, showing the forming wedges, male and female, in positions that engage the foam part and form an inverted taper or tapered bottom notch; and Figure 4 is a view similar to that of Figure 3 with the mold in the open position after the part has been thermoformed an inverted taper or tapered bottom notch.

DETAILED DESCRIPTION ILLUSTRATIVE MODALITIES Referring now to the drawings, the thermoformed portion 10 with an inverted taper or tapered bottom notch 12 formed in accordance with the principles of the present invention is illustrated in Figure 1. The part 10 is of a foam material such as foam of polystyrene, formed using a coupled metal tool. However, it should be recognized that the principles of the present invention can also be applied to sheet material and uncoupled metal tools. In the illustrated embodiment, part 10 is a lid or cover for a foam container that can be used in restaurants, schools, hospitals, hotels, food distributors, and the like, to contain items such as food. The inverted taper or tapered bottom notch 12 of this embodiment serves as part of a fastening structure for securing the part or cover 10 to another part, such as a tray, of a container. The ability to form the inverted taper or tapered bottom notch 12 in foam products allows for different locking or securing designs and leak resistant foam containers. In the past, the thermoforming of an inverted taper or tapered bottom notch with coupled metal tools has had the problem of the inability to demold the formed part, such as part 10, of the coupled tool, while maintaining the shape of the taper. Inverted or tapered lower notch 12. Coupled tool or mold 14, shown in Figures 2-4, overcomes this problem. The mold 14 includes a first mold half 16 defined by a forming cavity 18 which is attached to an upper platen 20. The forming cavity 18 defines a cavity 19. The mold 14 also includes a second mold half 22 defined by a forming plug 24 attached to a bottom plate 26. The forming plug 24 defines a plug 27 of a configuration complementary to the cavity 19. The tapered bottom notch 12 is formed by male forming wedges 28 mounted, so that they can be made an alternating movement, in the formed cavity 18 and female shaped wedges 30 rotatably mounted in the forming plug 24. The male forming wedges 28 are located in a groove 32 which is in the forming cavity 18 and are deflected by deflecting elements such as springs 34 to a retracted position outside the cavity 19. A force for moving the forming wedges 28 to a position extending into the cavity 1 9 is provided by the first actuating bolts 36 each of which is mounted, so as to be able to perform an alternate movement, in the forming cavity 18 and are deflected to a first position (shown in Figures 2 and 4) by a deflection element such as a spring 38. The first of the actuator bolts 36 includes a cut 40 and an inclined ramp 42. In the neutral position of the first of the actuator bolts 36 (figures 2 and 4), the male forming wedges 28 are in the slit 40 above the ramp 42. In this neutral position the male forming wedges 28 are retracted out of the cavity 19 under the force of deflection of the springs 34. The cavity formed 18 further includes second actuator bolts 44 which interact with the female formed wedges 30. The female shaped wedges 30 each include a rod 46 to which is attached a biasing member such as a spring 48. The springs 48 deflect each female shaped wedge 30 towards a first neutral position (figures 2 and 4). Each female shaped wedge 30 also includes a bolt engaging surface 50 and a tapered lower notch surface 52. For thermoforming a portion of foam 10, a sheet of foam material 54 is placed between the first mold half 16 and the second mold half 22 while the mold 14 is in the open position (Figure 2). The thermoforming process is started by joining the first mold half 16 and the second mold half 22 (Figure 3). When this occurs, the first of the actuator bolts 36 engages with the second half of the mold 22 by moving the first of the actuator bolts 36 upward, causing the inclined ramp 42 to engage the male forming wedges 28. This coupling moves. the female shaped wedges 28 towards the forming cavities 18 and towards the sheet of foam material 54. At the same time, the second of the actuating bolts 44 engages the sheet of foam material 54 and the surfaces 50 for coupling of the pin, on the female-shaped wedges 30. This coupling rotates the female-shaped wedges 30 to engage the sheet of the foam material 54 and the female-formed wedge 28, forming the inverted taper or tapered bottom notch. 12 when the mold 14 is closed. Once the foam part 10 and the inverted taper or tapered bottom notch 12 have been formed, the mold 14 is opened (Figure 4). When this occurs, the actuator bolts 36 and 44 move out of engagement with the second mold half 22 and return to their neutral positions (Figure 4). The male forming wedges 28 and the female wedges 30 also return to their neutral positions outside the coupling with the formed part 10, allowing sufficient clearance for the formed part 10 to be removed from the mold 14 without interference, while maintaining the shape of the inverted taper or tapered bottom notch 12. What has been described are mechanically driven forming wedges 28 and 30 that allow thermoforming tapered bottom notches 12 in foam portions 10 using coupled metal molds 14. This structure allows the part of foam 10 is demoulded from mold 14 without damage to the tapered bottom notch 12 or allowing part 10 to hang in mold 14, thus allowing a continuous thermoforming process. This allows the design of different closure designs on foam parts. As previously mentioned, the present invention can also be used in a thermoforming process using uncoupled metal molds. Although the present invention has been described with reference to the particular embodiments illustrated, those skilled in the art will recognize that various changes and variations may be made thereto without departing from the spirit and scope of the present invention. The modalities and obvious variations thereof are contemplated within the spirit and scope of the claimed invention, which are presented in the following claims:

Claims (10)

NOVELTY OF THE INVENTION Having described the above invention, it is considered as a novelty, and therefore, the content of the following is claimed as property: CLAIMS

1. A mold with forming wedges to form an inverted taper in a thermoformed foam part, characterized in that it comprises: a first mold half including a forming cavity, a male formed wedge, so as to be able to perform an alternating movement, in the first mold half for movement between a first position extending within the cavity and a second retracted position and outside the cavity, a first biasing member that engages the male forming wedge and deflects the wedge from male formed to the second position, a first actuator bolt mounted on the first mold half and a second actuator bolt mounted on the first mold half, the first actuator bolt can be moved from a first position to move the male forming wedge to the In the first position, the first actuator bolt can be moved to a second position that allows the male forming wedge to move to its second position. position, and, a second mold half including a shaped plug, a female formed wedge rotatably mounted on the second mold half and rotatable between a first position and a second position, the second mold half includes a portion for coupling the first actuator bolt, the female-shaped wedge includes a portion engaged by the second actuator bolt, whereby the coupling of the second actuator bolt rotates the female-formed wedge from the first position to the second position of the wedge. shaped female The mold according to claim 1, characterized in that it comprises a second biasing member that engages the female-shaped wedge and biases the female-shaped wedge to the first position. 3. The mold in accordance with the claim 1, characterized in that the female shaped wedge includes a portion in a configuration corresponding to the configuration of the inverted taper to be formed, and the female shaped wedge includes a portion complementary to the portion of the male shaped wedge. 4. A method for thermoforming tapered lower notches, in foam portions, using coupled metal molds and the demolding of the foam part, from the molds, while maintaining the shape of the lower tapered notch, characterized in that it comprises: a sheet of foam between a forming cavity having a retractable, male forming wedge, and a forming plug having a rotationally shaped female wedge, biasing the male forming wedge to a retracted position, outside the cavity formed, divert the female shaped wedge to a non-engaging position, move the forming cavity and the forming plug, together, move the male forming wedge towards the foam sheet, move the female shaped wedge towards the sheet foam and against the male formed wedge, to form a tapered lower notch, and, closing the forming cavity, forming a foam part. The method according to claim 4, characterized in that it comprises separating the forming cavity and the forming plug, retracting the male forming wedge, moving the female forming wedge of the foam sheet and removing the foam part from the foam sheet. the forming cavity and the forming plug. The method according to claim 4, characterized in that the movement of the male forming wedge comprises coupling a first actuating bolt on the forming cavity, with a portion of the forming plug and moving the first actuating bolt against the wedge of the former. formed male. The method according to claim 4, characterized in that the movement of the female-shaped wedge comprises coupling the female-shaped wedge with a second actuating bolt mounted on the forming cavity. 8. Mechanically driven forming wedges, to form lower tapered notches, in thermoformed foam parts, using coupled metal molds, characterized in that they comprise: a first mold half including a forming cavity, at least one male forming wedge mounted on the first mold half, for movement between a first position wherein the male forming wedge is retracted and out of the cavity, and a second position wherein the male forming wedge extends into the cavity, a first mounted driving bolt, so as to be able to performing an alternate movement, in the first mold half, for movement between a first position out of engagement with the male forming wedge and a second position in engagement with the male forming wedge, and, a second mold half including a forming plug, at least one female shaped wedge rotatably mounted on the second mold half, which can be rotated between a molding position lower tapered scale and a release position of the product. 9. The mechanically driven forming wedges according to claim 8, characterized in that they comprise a second actuator bolt mounted on the first mold half, in a position for coupling and rotating the female J? Ormadp wedge to the formed position of the lower tapered notch, when the first mold half and the second mold half move together. 10. The mechanically driven forming wedges according to claim 8, characterized in that they comprise a first deflection member in the first mold half, which couples the female shaped wedge and deflects the male forming wedge to retract and out of the cavity, a second biasing member in the first mold half, engages the first actuator bolt and biases the first actuator bolt to the first position, and a third biasing member in the second mold half, engaging the female shaped wedge and deflects the female shaped wedge to the product release position.