Patent Publication Number: US-2020276740-A1

Title: Apparatus associated with an injection moulding machine

Description:
The present invention relates to an apparatus associated with an injection moulding machine for moulding objects made from plastics material. 
     As an example of application, we refer to the moulding of stoppers for bottles comprising a body and a lid that are joined by an integral hinge or by a shape fit. These stoppers are very widespread, for example in shampoo or detergent bottles or the like. The body of the stopper is mounted on the bottle and the lid is able to move between a closed position and an open position and vice versa. 
     Producing said stoppers by moulding requires a moulding machine having ever more advanced performances. As less than tenths of a second represent thousands of parts more per hour, with a more rapid paying-off of the equipment costs, the mould manufacturers have continually developed novel solutions. Two technologies have arisen: IMC (In-Mould Closing) and IMA (In-Mould Assembly), both aiming at the mould producing a stopper already ready to be mounted on the bottle for which it is intended, avoiding a manual or automated phase of closure thereof. With IMC the pivoting lid is closed on the hinge on the body, and with IMA the body and the lid are moulded and then, by moving parts of the mould, they are fitted one in the other. 
     The document WO 2016/141461 (HUSKY) describes an IMC system provided with a movable member for moving the lid on the body. The movable member is actuated linearly by two electric servomotors along two orthogonal axes. Control of the servomotors is very complex and this is not the ideal for imparting curved pathways on the movable member. 
     The documents U.S. Pat. No. 8,827,678 B2 and U.S. Pat. No. 7,874,830 B2 (ERMO) describe respectively an IMA system and an IMC system in which a pneumatic or electric drive  104  with a single alternately controlled axis moves a transferable carriage  108  and rotates a pivoting part. Switching of the mechanical power to the transferable carriage  108  or the pivoting part is obtained with bistable kinematics. This system does not offer very fine positional control, which means that positional control cannot deviate from what was decided in the design phase, since it is limited by the cams and in any event subject to wear. 
     One objective of the present invention is to propose a system for the moulding and assembly of two parts that does not have the drawbacks of the prior art. 
     To this end an apparatus is proposed for coupling a first part and a second part after they have been produced by injection moulding, wherein it is possible to couple the apparatus to a mould mounted on an injection moulding machine able to mould said parts, the apparatus comprising:
         a linear runner;   a carriage that is mounted on the runner, where it can make translations in a movement direction;   a pivoting member that is mounted cantilevered on the carriage in order to revolve about an axis of revolution perpendicular to the direction of movement of the carriage, so that the revolution of the pivoting member causes one of the two parts to turn over and makes it possible to couple it with the other one;   a first electric drive mounted on the runner for moving the carriage along the runner;   a second electric drive mounted on the carriage in order to cause the pivoting member to revolve so as to couple the two parts.       

     In a preferred embodiment, the pivoting member is configured so as to revolve with a planetary movement about said perpendicular: this means that the pivoting member has its own longitudinal axis able to effect a revolution about said perpendicular axis while remaining at a certain distance therefrom. 
     In a preferred embodiment, the apparatus comprises two drives like the first drive, each being able to move in translation on a respective linear runner, the two runners being parallel and the pivoting member being mounted rotatably on each carriage and placed between the two carriages. Preferably, in this embodiment, the apparatus comprises two drives like the second drive, each drive being mounted on the corresponding carriage in order to rotate the pivoting member. In this way the balancing of the forces during the handling of the pivoting member is simplified and the precision of the placing thereof is improved. 
     In order to maximise savings, and in the case where the moulding machine does not comprise a second injection unit, there could be only one drive like the first drive. Having two of them does however simplify the balancing of forces (especially with two parallel runners) and improves the precision of the placing of the carriage. In the case where a single drive falls at the middle of the top portion of the mould, it is possible to use the system with dual drive. 
     In a preferred embodiment, the or each first and/or second drive is a rotary electric motor (another option is for example a linear actuator or motor). 
     In a preferred embodiment, the or each first rotary electric motor is connected to the respective carriage by means of a rotary threaded shaft mounted in engagement with a nut present in the carriage, a translation of the carriage corresponding to the rotation of the rotary threaded shaft. 
     In a preferred embodiment, the or each first rotary electric motor is connected to said pivoting member by means of a rotary threaded shaft mounted in engagement with a toothed wheel connected to the pivoting member, a rotation of the toothed wheel corresponding to the rotation of the rotary threaded shaft. 
     In a preferred embodiment, the first and/or the second drive comprises or consists of a rotary electric motor (another option is for example a linear actuator or motor). 
     In a preferred embodiment, in order to increase productivity, the apparatus comprises, on said two runners, a plurality of said pivoting members mounted in parallel and at a distance from each other, wherein the pivoting members are all connected to the same rotary shaft of one or each second drive. 
     Through the control of the first and second electric drives, it is possible to coordinate the path of the carriage and of the pivoting member in order to maximise productivity. 
     The apparatus can be adapted to produce a device in IMC (In-Mould Closing) or IMA (In-MouldAssembly) technology. 
     In the first case, the pivoting member is a bar, for example, in the case of stoppers, configured to come into contact with the lid and to push it onto the body. The bar preferably has portions with a larger diameter (“barrels”) corresponding to points intended to touch the cover in order to guarantee maximum extension of the contact and to avoid having to touch the edges of the stopper that have closed. 
     In the second case, the pivoting member is a mould portion in which the molten material is injected in order to mould the first part (for example a stopper lid), and then the mould portion is rotated in order to superimpose the first part and the second part (for example the body of a stopper) and to couple them to one another. 
     In a preferred embodiment, the apparatus comprises a logic unit (for example a microprocessor or an API) programmed to control the first and second electric drives and to coordinate the movements thereof. Automatic control of the electric motors, the apparatus offers numerous advantages, because electric motors afford very high performance and precision, which result in high productivity of the apparatus and of the moulding machine. 
     By means of the logic unit, it is possible to program the movement of one motor independently of the movement of the other motor, with the advantage that the pivoting member can have a very elaborate composite path suited to the application. The coordinated movements of the motors give more relative freedom to the project compared with documents U.S. Pat. No. 8,827,678 B2 and U.S. Pat. No. 7,874,830 B2, in which the movements are strictly a linear movement. 
     In particular, by means of the logic unit, it is possible to program the movement of the two motors so that the pivoting member has a composite path that remains contained inside a pre-established volume, a kind of safety limit that avoids impacts with obstacles or a component placed outside this volume. 
     Preferably, the apparatus comprises position sensors for determining the position of a carriage with respect to the respective runner and/or the angle of rotation of a pivoting member with respect to the carriage. 
     In a preferred embodiment for an IMC application, the logic unit is programmed: 
     a. to initially activate only the first drive, in order to move the pivoting member towards the part to be moved; 
     b. to deactivate the first drive and activate the second drive in order to shift the pivoting member and move one of the two parts; 
     c. to simultaneously activate the first drive and the second drive in order to return the assembly consisting a pivoting member and carriage to an idle position (of the start of the cycle). 
     In a preferred IMA application, the apparatus comprises:
         a third drive, which can be implemented for example like the first or second drive, and   a second mould portion into which molten material is injected in order to mould the second part (for example the body of a stopper).       

     The third drive serves to move the second mould portion linearly along an axis orthogonal to the plane identified by said movement direction and said rotation axis, for the purpose of moving the second portion towards the portion included in the pivoting member and to join the first and second parts. 
     The third drive may be a handling element already included in the moulding machine, for example as an oil-hydraulic or mechanical drive (a means for expelling the parts), or another actuator that is actuated by compressed air, oil or electricity. 
     In the context of said preferred IMA application, in a variant the logic unit is programmed:
         to initially activate only the first drive, in order to move the pivoting member containing the first part towards the second part;   next to activate the second drive at the same time as the first drive in order to shorten the path of the pivoting member (that is to say the pivoting member begins to rotate whereas it is still in a translation under the thrust of the first drive);   to continue to simultaneously activate the first drive and the second drive in order to bring the pivoting member above the second part;   next to activate only the third drive in order to fit the two parts one in the other.       

     In another IMA embodiment, it is possible first of all to rotate the pivoting member and next to move it in translation. 
     In another IMA embodiment, the logic unit is programmed:
         to initially activate only the first drive, in order to move the pivoting member containing the first part towards the second part;   next to activate only the second drive while blocking the first drive, in order to turn over the pivoting member and to bring it above the second part;   next to activate only the third drive in order to fit the two parts one in the other.       

     Another aspect of the invention relates to an injection moulding machine provided with said apparatus. 
    
    
     
       The features of the invention, as well as others, will emerge more clearly from a reading of the following description of an embodiment by way of example, provided in relation to the accompanying drawings, among which: 
         FIG. 1  shows a perspective view of a first moulding apparatus according to an embodiment in IMA technology; 
         FIG. 2  shows a plan view of the first apparatus; 
         FIG. 3  shows a view in cross section of the first apparatus along the plane III-III; 
         FIG. 4  shows a perspective view of a second moulding apparatus according to an embodiment in IMC technology; 
         FIG. 5  shows a plan view of the second apparatus; 
         FIG. 6  shows a diagram of paths for the first apparatus; 
         FIG. 7  shows another diagram of paths for the first apparatus; 
         FIG. 8  shows a diagram of paths for the second apparatus. 
     
    
    
     A stopper consisting of a body (the first part) and a lid (the second part) is described as an example of a moulded object. The apparatus  10  and the apparatus  60  are associated with a known moulding machine and with an injection mould that are not depicted. 
     In the figures, identical references designate identical parts. In order not to burden the figures, only a few elements are marked with a reference. 
       FIG. 1  shows an apparatus  10  for moulding and mounting the lid and body of a stopper. The apparatus  10  comprises a base consisting mainly of two parallel runners  12 . On the figures there are two runners  12 , but, in the case of large installations, it is possible to produce additional runners. 
     On each runner  12  there is mounted a movable carriage  18  able to move longitudinally along the runner  12  while being pushed or pulled by an electric motor  30  along an axis X. The two carriages  18  are connected together at the middle by one or more mould portions  40  that extend between the two carriages  18  perpendicularly to the direction of movement of the carriages  18 , along an axis Y. 
     The number of mould portions  40  varies according to the type of mould. 
     Each mould portion  40  is mounted on the carriage  18  so as to be able to revolve about the axis X with a planetary path, in other words it is offset eccentrically with respect to the axis Y. In this way the axis of the portion  40  revolves about the axis Y. 
     The electric motor  30  is of the rotary type and rotates a worm  32 , the axis of which is parallel to X and which is in engagement with a corresponding nut in the carriage  18 . Rotation of the worm  32  involves the advance of the carriage  18  on the runner  12  along the axis X. 
     On each carriage  18  there is mounted a second rotary electric motor  50 , the output shaft of which rotates a worm  52 , the axis of which is parallel to X and which is in engagement with the teeth on a toothed wheel  54  having the rotation axis Y. The toothed wheel  54  is connected to a disc or support that supports and rotates the portion  40 . 
     The coordinated control of the motors  30 ,  50  enables the apparatus  10  to function in IMA mode. Please see the diagrams in  FIGS. 6 and 7 , which illustrate a few types of path imposed on the portion  40 . 
     In  FIG. 6 , the portion  40  is initially moved along the axis X, by activation of the motor  30 , from a position Q to a position W. Then the motor  30  is stopped and the portion  40  revolves eccentrically about the axis Y, under the effect of the activation of the motor  50 , from the position W to a position E in which it is turned over vertically and is at a different height with respect to the runner  12 . 
     Finally, another electric motor (not shown) is activated in order to vertically lower the portion  40  until it joins a die  42  that contains the body of the stopper (position R). Coupling of the portion  40  with the die  42  causes the lid and body of the stopper to fit together. The latter movement, that is to say the one that assembles the two parts, may also take place in the opposite direction, preferably executed by the part-ejection means situated on the moulding machine. Or said latter movement is effected by an external actuator. 
     In  FIG. 7  the portion  40  is initially moved along the axis X, by activation of the motor  30 , from a position G to a position H. Then the motor  50  is activated at the same time as the motor  30  and the coordinated movement thereof obtains a composite path for the portion  40 . The latter commences for example to rise linearly with respect to the runner  12  or effects a parabola with its concavity turned downwards (end HI) while it revolves about the axis Y under the effect of the activation of the motor  50 . 
     Finally, as before, the portion  40  is lowered vertically until it joins a die  42  for fitting together between lid and body. Here also the variant exists with an opposite direction of movement. 
       FIGS. 4 and 5  show another apparatus  60  for moulding and closing the lid  90  and body  92  of a stopper one on the other ( FIG. 8 ). The lid  90  and the body  92  are moulded so as to be joined by an integral hinge. The cross section in  FIG. 3  is also valid for the apparatus  60 . 
     The apparatus  60  differs from the apparatus  10  only through the structure of the rotary part, and this is why we shall pass over the common details. 
     The two carriages  18  are connected together at the middle by one or more bars  70  that extend between the two carriages  18  perpendicularly to the direction of movement of the carriages  18 . The number of bars  70  varies according to the type of mould. 
     The toothed wheel  54  is connected to a disc  56  that supports the bar  70  eccentrically and rotates it. Each bar  70  is then mounted on the carriage  18  so as to be able to revolve about an axis Y perpendicular to the axis X, while remaining at a certain distance from the axis Y. In other words each bar  70  is mounted on the carriage  18  so as to be able to revolves about the axis Y in a planetary movement. 
     The coordinated control of the motors  30 ,  50  enables the apparatus  60  to function in IMC mode. 
     Please see the diagram in  FIG. 8 , which illustrates a type of path imposed on the bar  70  (drawn by way of exemplification as a circle). The bar  70  is initially moved along the axis X, by activation of the motor  30 , from a position J to a position K; in this phase the bar  70  has moved under the lid  90 . Then the motor  30  is stopped and the bar  70  revolves about the axis Y, under the effect of the activation of the motor  50 , from the position K to a position L. In revolving, the bar  70  pushes the lid  90  towards the body  92  until they couple with a click (position L).  FIG. 8  also shows successive positions of the lid  90 .