FR2884751A1 - Procedure for the installation of a cover on an object manufactured by injection casting of plastic material, to produce food containers, comprises insertion of a loose lead of a band for molded object - Google Patents

Abstract

A portion of the band is a knife (B) for solidifying the cover (L) with the molded object (O). The mold (100) comprises a flexible cover plate (400) laid out in a print (200, 300). The mold is equipped with a rotatable reel device (510) of the rolled up band. A plating unit includes an ejector (210)/a pin fixer for emerging the plates from the molding cavity and form a vent in the cavity. The cutting device knife is covered through the cover plates and a counterfoil in a housing emerged in the print. The counterfoil is equipped with a heel to form a molding wall of the cavity. An independent claim is included for a mold for injection molding plastics.

Description

The present invention relates to a method of laying a lid on a

  object manufactured by injection molding plastic material such as a food container and a mold for the manufacture by plastic injection of such an object.

  To easily demold the contents of a food container such as a disposable package for dairy dessert, one solution is to place on the bottom of the package a seal which normally closes a vent made through the wall of said bottom. By turning the package open and removing the lid, air can then be admitted through the vent, so that the contents of the package are easy to unmold.

  To manufacture such a package, a known injection technique, using a manufacturing mold mounted in a plastic injection molding machine, consists in: introducing into the mold held in the open position the head of a manipulator arm in order to deposit a lid folded in two in a cavity of an element of the mold, - to hold the lid in the mold element, for example, by depression, - to release the head of the manipulator arm from the mold, - to close the mold injecting material into the mold so that it covers the face of the lid facing towards the molding cavity of the object to be molded and wait for a few moments for the cooling of the material which will form the molded object, - open the mold to unmold the object.

  This manufacturing technique, in which a phase of opening of the mold is used to deposit the lid, has the disadvantage of extending the duration of the manufacturing cycle of the molded object because it is necessary to introduce the head of the arm manipulator in the middle of the mold then remove it before ordering its closure.

  The object of the invention is therefore to provide a method of laying a lid on a package that does not slow down the manufacturing cycle and a manufacturing mold that does not implement a manipulator arm.

  For this purpose, the method of laying a peelable seal on an object manufactured by injection molding of plastic material is characterized in that it consists in advancing one step a free end of a strip of material in a mold cavity for the molded article, supporting said free end in said mold cavity, and then cutting a portion of the strip outside the mold cavity of the molded article to form a peelable peelable seal capable of to be secured to the object during its manufacture.

  The band feeding operation can be implemented during the opening phase of the mold without slowing down its operating cycle.

  A mold for the manufacture by plastic injection of an object is also proposed. The mold comprises at least one cavity, a closure plate disposed opposite said cavity, which are movable relative to each other between a mold opening position and a mold closing position. , the mold being provided with a device for laying a lid on the molded object.

  According to the invention, the device comprises means for feeding a strip to advance it one step between said fingerprint and the closure plate in the open position of the mold, so that its free end may be brought into a mold cavity for the molded object, the device further comprising cutting means adapted to cut the strip outside the mold cavity and means for plating said free end in the mold cavity so that said free end can form a peelable operculum on the molded object.

  This design of the mold of the invention, which does not require the use of a manipulator arm, is economical to manufacture.

  According to an additional feature of the invention, the feeding means comprise a reel capable of containing a wound strip, the reel being provided with a rotation drive means or moved in translation with the aid of a device stepping type.

  According to an additional feature of the invention, the plating means comprise a spring biased ejector disposed in said cavity so as to open into the mold cavity under the location of the lid. This ejector holds the lid in place until the arrival of the flow of material, under the pressure of which it disappears.

  According to an additional feature of the invention, the plating means comprise a fixed pin disposed in said cavity so as to open into the mold cavity under the location of the lid, and thus form a vent in the molded object.

  According to an additional feature of the invention, the cutting means comprise a knife slidably mounted against a biasing means and which is capable of cooperating with an anvil arranged in facing relation.

  According to an additional feature of the invention, the knife protrudes through the closure plate, the anvil being disposed in an open housing in the direction of the closure plate and which opens into said cavity.

  According to an additional characteristic of the invention, the anvil is provided with a bead arranged so as to be able to locally form a molding wall of the molding cavity, in the closed position of the mold, on the one hand, to form Locally a molding wall of the molded object and, on the other hand, constitute, with the closure plate, a means for isolating a free portion of the lid, intended to form a gripping tab.

  According to an additional feature of the invention, the anvil is movably mounted in the housing between a position where the heel locally forms a molding wall of the molding cavity and a withdrawal position, where the heel penetrates the housing. interior of the housing to release the tongue and thus allow the demolding of the molded object without damaging the lid.

  According to an additional feature of the invention, the mold is used to make food containers.

  The characteristics of the invention mentioned above, as well as others, will appear more clearly on reading the following description of an exemplary embodiment, said description being made in connection with the attached drawings, among which: FIG. . 1 is a sectional view of a manufacturing mold shown in a partially open position according to the invention, FIG. 2 is a sectional view of a manufacturing mold shown in a closed position according to the invention, FIG. 3 shows a sectional view of a manufacturing mold shown during a material injection phase according to the invention, FIG. 4 is a sectional view of a manufacturing mold shown in a partially open position and in which a molded object according to the invention appears, and FIG. 5 is a perspective view of a molded article that has been manufactured by a manufacturing mold according to the invention.

  The plastic injection molding mold 100 shown in FIG. 1 is intended for the manufacture of molded articles. It should be mounted in an injection press, not shown, to implement its operation.

  The mold 100 essentially comprises a male cavity 200 commonly called piston in the profession, a female cavity 300 and a closure plate 400 between which plastic material maintained in the pasty state can be injected to form a molded object. The closure plate 400 here comprises a nozzle 410 for injection of the plastic material of the hot runner type.

  The mold 100 is provided with guide means M, represented by simple thin single lines, allowing a relative translation along the same direction of the impressions 200, 300 and the closure plate 300.

  The cavities 200, 300 and the closure plate 400 are thus made mutually movable between an open position of the mold 100, visible in FIG. 1, where they do not touch and a closed position of the mold 100, visible in FIG. 2, where they are in mutual contact in pairs at a common joint plane J1 and J2 while leaving between them a thin volume capable of constituting a mold cavity V. The mold 100 is also provided with means fixing device allowing it to be mounted between the plates of an injection molding machine.

  The mold 100 is used in the following manner. The mold 100 is first mounted in an injection molding machine. In a first step, the mold 100 is closed by applying the imprints 200 and 300 and the closure plate 400 against each other by means of closing the press, as shown in FIG. 2, then in a second step, plastic is injected through the injection nozzle 410 to fill the mold cavity V between the impressions 200 and 300 and the closure plate 400 to form a molded object O as shown in FIG. 3.

  The mold 100 is then kept closed for a few moments to allow a first cooling of the object O, then in a third step, visible in FIG. 4, the mold 100 is opened to allow demolding of the object O. The object O is then ejected by blowing air under pressure from the piston 200. In practice, the impressions 200 and 300 are separated from one another. greater distance than that shown in this FIG. 4 to allow the complete exit of the object O from the mold 100.

  The molded object O adhering to the walls of the mold 100 can thus be easily demolded. Such a molded object takes the form, for example, of a food container to be filled by a milk dessert, a fish mousse or any other food dosed to be demolded. To consume such a product, especially when it is associated with a caramel topping, it is advantageous to return the food container, which will have previously removed a sealed film closing its opening, to unmold its contents perfectly. For this purpose, the bottom of the food container is frequently provided with a cover which normally masks a vent. It is then sufficient for the consumer to remove the lid so that its content is easy to unmold without dislocation while being covered, if necessary, by its topping.

  In FIG. 1, the mold 100 is provided with a device 500 for laying a lid L on the molded object. This device has the advantage of not using a manipulator arm.

  The device 500 allows, in the embodiment shown in this patent application, the laying of a lid preferably located on the bottom of the food container.

  Overall, the device 500 performs the introduction into the mold cavity V of the mold 100 of a piece of a defined length of a strip of material, such as peelable film, which is cut out of the molding zone , then its maintenance inside thereof so as to constitute a peelable seal which will be associated with the bottom of the molded object at the end of its manufacture.

  The device 500 comprises for this purpose means for feeding the strip in the molding cavity V, means for cutting said strip B and means 25 for plating the strip B in the mold cavity V of the mold 100.

  The means for feeding the band B comprise a coil 510 capable of containing a strip B of wound plastic material and which is arranged in such a way that the band B can advance between the female cavity 300 and the closure plate 400 of the mold 100 maintained in its open position. The coil 510 is optionally provided with a rotation drive means or is moved in translation by a step-type feeding device, not shown, and capable of advancing the band B by one step P corresponding to the length of a lid as shown by the arrows F1 and F2 in this FIG. 1.

  The cutting means of the band B comprise a knife 530 intended to cooperate with an anvil 520.

  The knife 530 consists of a bevelled pin slidably mounted in the closure plate 400 against a biasing means 540, constituted in this FIG. 1 of a spring. The cutting portion of the knife 530 is oriented to protrude through said closure plate 400 towards the female cavity 300.

  The anvil 520 is placed in an open housing 310, provided in the female cavity 300 so as to be positioned facing the knife 530. The height of the anvil 520 is substantially the same as that of the housing 310 so that its visible main face 522 can be arranged at the common joint plane Ji of the female cavity 300 and the closure plate 400. It will be noted that the housing 310 opens into the female cavity 300.

  Thus, in the closed position of the mold 100 shown in FIG. 2, the knife 530 cooperates with the face 522 of the anvil 520 to cut a portion of the band B to form an operculum L. In FIG. 2, the anvil 520 is also provided with a heel 524 which opens into the mold cavity V to locally form a molding wall of the mold cavity V in the closed position of the mold 100, for one hand, locally forming a molding wall of the molded object and, on the other hand, forming, with the closure plate 400, a means for isolating a free portion of the lid L which is thus sandwiched so that it can not be covered by the plastic material when it is injected into the mold 100. In FIGS. 4 and 5, this free portion carries the index G and forms a tongue to remove the lid L of the molded object O. The anvil 520 is also mounted movably in the housing 310, the size of which is adapted to the stroke thereof, through a mechanical connection, not shown, slaved to the mechanism of opening and closing the mold. Anvil 520 is thus made movable between a position visible in FIG. 2 where the heel 524 opens through the female cavity 300 to form locally a molding wall of the molding cavity and a withdrawal position, visible in FIG. 4, where the heel 524 penetrates inside the housing 310 so that it can no longer be interposed between the molded object 0 and the tongue G of the lid L to thereby allow the demolding of the molded object O without damaging said operculum.

  In FIG. 2, the mold 100 is provided with means for plating the lid L in the molding cavity V so as to hold it against a wall of the closing plate 400 capable of delimiting the external face of the bottom wall of the mold. molded object O so that said lid can be secured to said outer face during the step of injecting the plastic material. These plating means comprise a spring-biased ejector 210 and a fixed spindle 220 arranged as the ejector 210, through the piston 200. The ejector 210 and the spindle 220 open into the mold cavity V at a distance place under the location of the operculum L. It will be noted in FIG. 3, that under the effect of the pressure of the flow of the injected material arriving in the molding cavity, the ejector 210, whose end is tapered without being visible in this FIG. 3, is moved back into the piston 200 after supporting the end of said tongue.

  The pin 220 which protrudes from the molding wall of the piston 200 which thus delimits the inner face of the bottom of the molded object O, also makes it possible to form a vent, visible only in FIG. 4, through the bottom of said molded object O. This vent e, located under the lid L, is thus closed by him at the end of the manufacture of the molded object O. The operation of the mold 100 provided with its device 500 laying a lid L is as follows. In the open position of the mold 100, the spool 500 is rotated by its drive means to advance the band B by a pitch P between the female footprint 300 and the closure plate 400 to be placed in the mold cavity V. The mold 100 is then closed, a portion of the band B is then cut by the knife 530 cooperating with the anvil 520 to form a lid L whose end, intended to form a tongue G, is then retained between the anvil 520 and the closure plate 400 and the other end is held against the closure plate 400 by the spring-biased ejector 210 and the pin 220.

  Paste plastic is then injected through the injection nozzle 410 to fill the mold cavity V to produce a molded article 0. It will be appreciated that in view of the operculum L plating against the closure plate 400, the injected material can not infiltrate between said lid and said closure plate, which will facilitate subsequent removal of the molded object.

  After a short cooling, the lid L is thermally sealed, then the mold 100 is opened to allow the evacuation of the molded object O. The anvil 520 is then brought into its retracted position by the opening mechanism and closure of the mold to facilitate the exit of the tab G of the lid L which is then secured to the bottom of the object O. The air blown from the piston 200 then pushes the molded object O which can then to be evacuated out of the mold 100.

  In FIG. 5, the manufactured object O is thus provided with a lid L that covers and closes the vent made in its bottom D. It will be noted that the non-integral portion of the lid L, that is to say its free part, and which is arranged in the extension of the bottom D, forms a G grip tongue.

  The user can thus grasp this tongue G to remove the lid L from the molded object O in order to clear the vent to facilitate the demolding of the food product that it may contain.

  The method makes it possible to produce molded objects such as food containers with mold release lids more quickly compared to techniques known to date.

  The associated manufacturing mold is of a simple design and is inexpensive to make.

  This application, described in connection with a single-cavity type mold is expandable to a multi-cavity type mold.

Claims (11)

  1) A method for laying a peelable (L) lid on an object (0) produced by plastic injection molding, characterized in that it consists in advancing by one step (P) a free end of a strip (B) of material in a molding cavity (V) for the molded object (0), supporting said free end in said molding cavity (V), and then cutting a portion of the strip (B) outside the mold cavity (V) of the molded object (0) so as to constitute a peelable lid (L) capable of being secured to the object (0) during its manufacture.   2) Mold (100) for the manufacture by plastic injection of an object (0), the mold (100) comprising at least one cavity (200, 300), a closing plate (400) disposed facing said cavity, which are movable relative to each other between an open position of the mold (100) and a closed position of the mold (100), the mold (100) being provided with a device (500) for placing a lid (L) on the molded object (0), characterized in that the device (500) comprises means (510) for feeding a strip (B) for the advancing one step (P) between said cavity (200, 300) and the closure plate (400) in the open position of the mold (100), so that its free end can be brought into a molding cavity (V) for the molded article (0), cutting means adapted to cut the strip (B) outside the molding cavity (V) and plating means (210, 220) of said end free in the cavity of m oulage (V) so that said free end can form a peelable operculum (L) on the molded object (0).   3) Mold (100) according to claim 2, characterized in that the feeding means comprise a coil (510) capable of containing a strip (B) wound, the coil (510) being provided with a drive means rotating.   4) Mold (100) according to claim 2, characterized in that the feeding means comprises a coil (510) capable of containing a strip (B) wound, the coil (510) being movable in translation by a stepping device type step.   5) Mold (100) according to claim 2, 3 or 4, characterized in that the plating means comprise a spring-biased ejector (210) disposed in the cavity (200, 300) so as to open into the cavity of molding (V) under the location of the seal (L).   6) mold (100) according to any one of claims 2 to 5, characterized in that the plating means comprise a pin (220) fixed disposed in the cavity (200, 300) so as to open into the cavity of molding (V) under the location of the seal (L), and to form a vent (e) in the molded object (0).   7) Mold (100) according to any one of claims 2 to 6, characterized in that the cutting means comprises a knife (530) slidably mounted against a biasing means and which is capable of cooperating with an anvil (520) disposed vis-a-vis.   8) Mold (100) according to claim 7, characterized in that the knife (530) protrudes through the closure plate (400), the anvil (520) being arranged in a housing (310) open in the direction the closure plate (400) and which opens into the cavity (300).   9) Mold (100) according to claim 7 or 8, characterized in that the anvil (520) is provided with a heel (524) arranged to form locally a molding wall of the mold cavity (V ), in the closed position of the mold (100), on the one hand, locally form a molding wall of the molded object (0) and, on the other hand, constitute with the closure plate (400) , a means for isolating a free portion of the lid (L), intended to form a gripping tongue (G).   10) Mold (100) according to claim 9, characterized in that the anvil (520) is movably mounted in the housing (310) between a position where the heel (524) locally forms a cavity wall of the cavity molding (V) and a withdrawal position, wherein the heel (524) penetrates inside the housing (310) to release the tongue (G) and thus allow the molded object (0) to be demolded without damaging the operculum (L).   11) Use of the mold (100) according to any one of claims 2 to 10 for manufacturing food containers.