Patent Application
20090212459
The present invention concerns a method of the post-treatment of blanks, e.g. preforms produced in an injection molding mold and a system therefor.
Injection molding is one of the most important methods of producing blanks or moldings. In that procedure the molding material which is generally originally in the form of powder or granular material is heated, plasticized and pressed under a high pressure into a suitable molding tool. The molding material hardens in the molding tool and is then removed from the opened tool.
Commercially available PET bottles are generally produced by expansion blow molding of a hollow body preform or hollow body parison. In that case the hollow body preform is produced in a first step by injection molding. The expansion blow molding operation which follows the injection molding operation can be effected either immediately after production of the hollow body preform or at a later moment in time.
A high level of complication and expenditure is necessary in production of the corresponding injection molding molds as the injection molding mold on the one hand must be designed for very high pressures and on the other hand it must also have suitably heated and/or cooled passages.
Usually an injection molding tool for the production of PET preforms comprises a large number of, for example 96, cavities, into which tool cores of a suitable configuration are introduced. When the tool is closed, that is to say when the core is inserted into the corresponding cavity, a space, referred to as the mold cavity or mold space, is formed between the core on the one hand and the cavity on the other hand. The plasticized plastic material, for example PET, is then injected under high pressure into that space. As soon as the PET preform has sufficiently cooled the mold can be opened and the preform removed.
The cycle time, that is to say the duration of the period of time between the beginning of the injection molding operation for a preform and the beginning of the injection molding operation for a subsequent preform is generally somewhat longer than the mold stand time. The cycle time is composed of the closing time, that is to say the time that the injection molding mold requires to close, the mold stand time, the opening time, that is to say the time that the injection molding mold requires to open, and a pause time. The pause time is generally determined by the time required to remove the preform from the opened mold. The mold stand time is the duration of the period of time between closing and opening of the tool. In other words the mold stand time is the time during which the tool is not moved in the closed condition.
To reduce the cycle times, that is to say the time from one injection operation to the next, it is already usual for the preform to be removed from the mold at a very early moment in time at which the preform is already solid at its outside surfaces but the internal region thereof, referred to as the preform core, is still fluid. In that condition the preform is generally transferred into what is referred to as a receiving plate which comprises a group of receiving cavities. Thus for example in what are referred to as vertical tools, that is to say those injection molding tools which are opened by a vertical movement of the one tool portion relative to the other, it is usual for the mold tool to be already opened after for example 10 seconds, for a receiving plate with corresponding receiving cavities to be moved into the mold, for the individual preforms to be allowed to drop into the receiving cavities by means of the force of gravity, for the receiving plate with the preforms to be moved out of the tool, for the mold to be closed again and for the next injection molding operation to begin. During the next injection molding operation the previous preforms remain in the receiving cavity which is usually cooled.
Embodiments are also known in which the individual preforms are removed from the mold by means of a gripper unit and transferred into the receiving plate arranged outside the tool mold.
As the preform must remain in the receiving cavity of the state of the art for a comparatively long time for the cooling operation, so that generally the next preform can already be removed from the injection molding tool before the preform in the receiving cavity has cooled down to such an extent that it can be removed without the risk of damage, it is already usual practice to employ receiving plates having a plurality of groups of receiving cavities, wherein each group has as many receiving cavities as the injection molding tool provides preforms per injection cycle. The individual receiving cavity groups are then successively filled with preforms so that the individual preform can remain in the receiving cavity for longer than an injection molding cycle.
Such receiving plates however are correspondingly large and can only be controlled with a very great deal of complication and expenditure.
In order further to reduce the cycle time quite a number of endeavours have been made in recent years to already remove the preform from the injection molding mold at an early moment in time. As the preform is still relatively soft at such an early moment in time high demands are made on the post-treatment procedure. Thus occasional proposes have already been set forth for occasionally cooling or post-treating the preform held in a receiving cavity, with a post-treatment pin which is introduced into the preform. In the known apparatuses with a post-treatment pin however it is only briefly engaged into the preform.
WO 03/097326 already discloses an apparatus for the post-treatment of preforms produced in an injection molding mold. That machine has a tool block with two different groups of tool cores. In addition the arrangement has four receiving plates arranged on a cube, as well as two pin plates. After the preforms have been produced in the injection molding machine, the latter is opened and the tool block turned in such a way that the other group of tool cores can co-operate with the tool cavities. The preforms produced by means of injection molding are now on the free tool cores. From there they are now transferred into a receiving plate with corresponding receiving cavities. The receiving cube with the individual receiving plates is then turned through 90° and a pin plate is briefly moved into the preforms. Thereafter the pin plate is moved out again and the receiving cube turned through a further 90° and another pin plate is again introduced into the preforms.
The frequent inward and outward movement of the post-treatment pins however does not guarantee reliable post-treatment of the interior of the preforms.
Taking that state of the art as the basic starting point therefore the object of the present invention is to provide a method of and a system for the post-treatment of preforms produced in an injection molding mold, which on the one hand allows early removal of the preform from the injection molding tool and on the other hand allows reliable post-treatment in particular of the interior of the preform after removal from the injection molding mold.
In regard to the method the specified object is attained in that the preform is transferred out of the injection molding mold into a receiving cavity whose internal shape substantially corresponds to the external shape of the preform, and a post-treatment pin whose external shape substantially corresponds to the internal shape of the preform is introduced into the preform and remains there for a period of time which is longer than the cycle time of the injection molding mold. It is essential therefore that post-treatment of the preform is effected in a receiving cavity into which a corresponding post-treatment pin has been introduced, wherein the pin remains in the preform for some time which is markedly longer than the mold stand time of the injection molding machine.
More specifically, in accordance with the invention, a system is provided for the post-treatment of preforms (7) produced in an injection molding mold. The system includes at least two post-treatment tools each of which have its own receiving plate (4) which has a group of receiving cavities (2) and its own pin plate (6) which has a group of post-treatment pins (3), and
a device for transferring the preforms (7) out of the injection molding mold alternately into the at least two post-treatment tools,
wherein the pin plate (6) and the receiving plate (4) of each post-treatment tool are reciprocatingly movable relative to each other between an open position in which the post-treatment pins (3) are arranged outside the receiving cavities (2) and a post-treatment position in which the post-treatment pins (3) are arranged at least partially in the receiving cavities (2).
The receiving cavity can have either an open and a closed end or two open ends. The configuration with an open and a closed end has the advantage that the receiving cavity also follows the external shape of the preform in the bottom region thereof.
The embodiment with two open ends makes it possible to produce specifically adapted cooling fluid flows within the receiving cavity.
In tests it has been found that the post-treatment pin remains in the preform if possible at least for double the mold stand time, preferably at least three times the mold stand time and particularly preferably at least four times the mold stand time.
In injection molding procedures, frequently all operating movements are adapted to the cycle time. Therefore an alternative configuration of the method provides that the post-treatment pin remains in the preform at least for double the cycle time, preferably at least three times the cycle time and particularly preferably at least four times the cycle time.
Furthermore a particularly preferred embodiment provides that the preform is prevented from coming into contact with the internal surface of the receiving cavity by means of a fluid, preferably a gaseous fluid, which is introduced into the receiving cavity through an opening preferably in the proximity of a closed end of the receiving cavity. When the preform is transferred into the receiving cavity the preform is under some circumstances still soft so that any contact between the preform on the one hand and the internal surface of the receiving cavity on the other hand would result in irreversible deformation of or damage to the preform. Therefore the preform is advantageously held on an air cushion which prevents direct contact. A further particularly preferred embodiment provides that a fluid, preferably a gaseous fluid, is introduced into the preform at least at times through an opening in the post-treatment pin, wherein in a particularly preferred embodiment the fluid is introduced into the preform in such a way that the preform is further pressed into the receiving cavity by the fluid as it flows out and substantially without direct contact between the post-treatment pin and the preform.
There is thus a condition in which the preform touches substantially neither the receiving cavity nor the post-treatment pin, but is only held on the air cushions which are provided by the receiving cavity on the one hand and the post-treatment pin on the other hand. For definitive shaping of the preform the post-treatment pin can then be still further introduced into the receiving cavity so that, if the supply of fluid through the receiving cavity is shut down for a brief moment, the external wall of the preform is pressed against the internal wall of the receiving cavity. In the same way contact could also occur between the internal wall of the preform and the external surface of the post-treatment pin. Tests have shown however that the best results are achieved if contact occurs only at the receiving cavity but not at the post-treatment pin.
As an alternative thereto it is also possible for the post-treatment pin to be so dimensioned that the preform shrinks upon cooling on to the post-treatment pin. In that respect it is desirable if the outside diameter of the receiving finger is substantially equal to the inside diameter of the blank to be removed, in the cooled condition. In that way the receiving finger only slightly influences contraction of the material upon cooling and the blank can be removed from the receiving finger after cooling, with a comparatively low force.
It will be appreciated that it is also possible for the preform firstly to be transferred on to a post-treatment pin whose external shape substantially corresponds to the internal shape of the preform and to provide a receiving cavity which is movable relative to the post-treatment pin in such a way that it surrounds the post-treatment finger and the preform arranged thereon. In that respect it is desirable if the receiving cavity has an internal wall which approximately corresponds to the external shape of the preform.
A preferred embodiment uses a receiving cavity having two open ends. Cooling fluid is introduced into the receiving cavity in such a way that the fluid flows along the outside of the preform and issues from both ends of the receiving cavity. That makes it possible to provide for very specifically targeted cooling of the preform.
In regard to the system the foregoing object is attained by a system for the post-treatment of preforms produced in an injection molding mold, comprising at least two post-treatment tools which each have a receiving plate which has a group of receiving cavities and a pin plate which has a group of post-treatment pins, and a device for transferring the preforms out of the injection molding mold alternately into the at least two post-treatment tools, wherein the pin plate and the receiving plate of each post-treatment tool are reciprocatingly movable relative to each other between an open position in which the post-treatment pins are arranged outside the receiving cavities and a post-treatment position in which the post-treatment pins are arranged at least partially in the receiving cavities.
In contrast to the state of the art it is therefore not provided that a receiving plate co-operates successively with different pin plates, but each receiving plate has its own pin plate with which it exclusively co-operates. The at least two post-treatment tools are alternately occupied by preforms.
That ensures that the pin plate co-operates with the receiving plate over a period of time which is markedly longer than the cycle time of the injection molding tool, and that permits effective post-treatment of the preforms.
Furthermore a preferred embodiment provides that the transfer device is a gripper plate with gripper elements for gripping the preforms in the injection molding mold and transporting the preforms to the post-treatment tool. In other words, as soon as the injection molding mold is opened, the gripper plate moves thereinto and grips the preforms and transfers them from the injection molding mold alternately into the individual post-treatment tools.
As an alternative thereto the receiving plate of a post-treatment tool can also be moved into the opened tool mold, wherein there is provided an ejection system having ejection elements with which the preforms can be released from the injection molding mold and can be transferred into the receiving plate so that by virtue of the force of gravity they can be passed over.
In a further alternative embodiment in the open position of the post-treatment tool the pin plate or the receiving plate is reciprocatingly movable laterally between the open position in which the pins are in opposite relationship to the receiving cavities and a transfer position in which the pins and the receiving cavities are not in opposite relationship. In that movement the pin plate and the receiving plate remain substantially parallel to each other and do not alter their spacing. The movement occurs substantially exclusively in a lateral direction. If for example the receiving plate is laterally movable the movement takes place within the plane of the receiving plate. In other words, in a first step the post-treatment tool comprising the receiving plate and the associated pin plate can be moved into the opened position by for example the pin plate being moved relative to the receiving plate in a direction perpendicular to the plate planes. As soon as the post-treatment tool is in the opened position, for example the receiving plate can be moved beside the pin plate laterally, that is to say without the spacing between the pin plate and the receiving plate changing, so that the preforms can be received or the preforms can be removed.
Furthermore in a particularly preferred embodiment there is provided a robot unit with which each post-treatment tool can be moved into a readiness position in which the post-treatment tool can be moved into the open position and can be equipped with the preforms, and into a removal position in which the post-treatment tool can be moved into the opened position and the preforms can be removed.
In that respect for example the robot unit can be so designed that each post-treatment tool can be moved into a waiting position. In other words there are at least three locations or positions into which the individual post-treatment tools can be moved by the robot unit, the readiness position, the waiting position and the removal position. While the post-treatment tool is in the waiting position post-treatment of the preforms is effected within the tool.
By way of example the robot unit can be a rotational unit which is rotatable about an axis of rotation, wherein the receiving plates are fixed to the rotational unit so that they can be moved from the readiness position into the removal position by rotation of the rotational unit. In that respect in a preferred embodiment it is provided that in the removal position the corresponding post-treatment tool can be moved into the open position, wherein the receiving plate and the pin plate are movable in the open position relative to each other laterally into an ejection position in which the preforms can be ejected from the receiving plate. In a particularly preferred embodiment in the ejection position the open ends of the receiving cavities are so arranged that the preforms can be ejected from the receiving cavities because of their own weight.
The transfer position can be arranged either within the injection molding mold or outside it.
In a further particularly preferred embodiment the pin plate has through openings, through which the preforms can be introduced into and/or ejected from the receiving cavities. That has the advantage that, for receiving the preforms or for removal thereof, the receiving plate and the pin plate only have to be displaced a small distance laterally relative to each other as then the preforms are received or removed respectively by way of the through openings.
In an alternative embodiment it is provided that the pin plate has gripper elements, wherein a gripper element is associated with each receiving cavity or each pin respectively and the pin plate and the receiving plate are movable relative to each other laterally between two positions and are movable towards and away from each other in both positions so that in the one position the post-treatment pins can be introduced into the receiving cavities and removed again and in the other position the preforms can be removed from the receiving cavities by means of the gripper elements.
A further preferred embodiment has a positioning device for positioning the first post-treatment tool in at least one positioning direction, wherein the at least two post-treatment tools are connected together so that, with the positioning device for positioning the first post-treatment tool, at least one further post-treatment tool can be positioned by corresponding positioning of the first post-treatment tool.
That markedly simplifies the positioning mechanism. There is no need for a dedicated positioning mechanism to be associated with each post-treatment tool. Rather the positioning mechanism moves all post-treatment tools as a whole. As there is only ever one post-treatment tool that is fitted with a further set of preforms to be post-treated, the position of the other post-treatment tools in which previous groups of preforms are being post-treated is not of significance.
It is further advantageous if each post-treatment tool has an opening and closing device for moving the pin plate and the receiving plate between the open position and the post-treatment position.
In that respect a particularly preferred embodiment provides that the positioning device and the opening and closing device are oriented in mutually co-linear relationship.
Thus it is possible for example that the at least two post-treatment tools are arranged in mutually juxtaposed relationship in the positioning direction, wherein the receiving plate of a post-treatment tool is connected to the pin plate of another post-treatment tool. When now the opening and closing device of a post-treatment tool is actuated, that has the effect that the receiving plate and all further post-treatment tools mounted thereto is moved relative to the pin plate and all further post-treatment tools mounted thereto.
By way of example the positioning device can comprise a linear drive, preferably a servo motor. The at least two post-treatment tools can be arranged displaceably on rails.
In a preferred embodiment the opening and closing device is a stroke device. By way of example a pneumatic cylinder or an electric drive can be used here.
As an alternative thereto it is also possible to provide only one opening and closing device. In that case it is advantageous if the opening direction of all post-treatment tools is oriented in the positioning direction, all post-treatment tools are arranged in a row in mutually juxtaposed relationship in the positioning direction, the positioning device is connected to the first post-treatment tool of the row and the opening and closing device is connected to the last post-treatment tool of the row. In addition it is desirable if all post-treatment tools have a locking device which in the locked position prevents opening of the post-treatment tool. According to which respective post-treatment tool is to be opened, the locking device in question can then be released. When now the opening and closing device is actuated it ‘pulls’ at the one end of the row of post-treatment tools while the positioning device ‘retains’ the other end of the row. Consequently the post-treatment tool which is not unlocked will open. It is therefore possible to position and open a plurality of post-treatment tools with only one positioning device and only one opening and closing device.
Furthermore there can be provided a guide element for guiding the blank out of the post-treatment tool which when the post-treatment tool is opened can be moved between the receiving plate and the pin plate of the post-treatment tool. The guide element ensures that the preforms are guided upon ejection out of the post-treatment tool.
In that respect the guide element can be a substantially U-shaped rail. Possibly discharge of the preforms can also be expedited by the provision of a compressed air source or a vacuum source.
In a particularly preferred embodiment the guide element is provided on the device for transferring the preforms from the injection molding mold into the post-treatment tools.
In a further preferred embodiment at least one receiving plate is at the same time in the form of a pin plate. In other words that plate has both a group of receiving cavities and also a group of post-treatment pins. In that respect the group of receiving cavities belongs to a different post-treatment tool, from the group of post-treatment pins. By virtue of such a design configuration it is possible to save on material and thus weight in the production of the post-treatment tools.
Advantageously the post-treatment tools are arranged in succession in the opening direction, wherein preferably the post-treatment pins and the receiving cavities of two adjacently arranged post-treatment tools are displaced relative to each other by approximately half the spacing of two adjacent receiving cavities of a receiving plate. For the situation where there is provided a plate which has both receiving cavities and also post-treatment pins, this means that a post-treatment pin is arranged approximately in the middle between two receiving cavities.
Furthermore a particularly preferred embodiment provides that the at least two post-treatment tools each additionally have a bottom plate with a group of bottom post-treatment devices, wherein the receiving cavities are open on both sides. When a preform is introduced into such a receiving cavity, the bottom of the preform is freely accessible by virtue of the open end of the bottom. In order to ensure effective post-treatment also of the bottom of the preform, there is therefore provided a bottom post-treatment device. That can comprise for example a nozzle with which cooling fluid can be directed on to the bottom of the preform.
A particularly preferred embodiment is one in which at least one plate is at the same time the bottom plate of a first post-treatment tool, the receiving plate of a second post-treatment tool and the pin plate of a third post-treatment tool. That multifunction means that it is possible to save on material for the production of post-treatment tools.
Another particularly preferred embodiment provides that the receiving plate has a feed means for a cooling fluid, wherein the feed means for cooling fluid is so arranged that cooling fluid can be passed into each receiving cavity.
In that respect in a desirable embodiment it is provided that the receiving cavities have two open sides and the feed means for cooling fluid is so arranged that the cooling fluid is divided and leaves the receiving cavity at both open sides. The flow of cooling fluid is thus divided and serves for cooling different portions of the preform. By virtue of a suitable choice of the flow cross-sections, that is to say the spacing between the receiving cavity on the one hand and the preform on the other hand, it is possible to set the amount of cooling fluid which is provided for the post-treatment of various portions of the preform. Thus each portion of the preform can be cooled or post-treated in a specifically targeted fashion by that measure according to the invention.
In that respect in a particularly preferred embodiment the feed means for cooling fluid has a swirl element which is so designed that it imparts a circular rotational movement to the cooling fluid. The consequence of this is that the cooling fluid not only flows past the preform in the longitudinal direction thereof but also flows around the preform in a helical path.
The swirl element for example can be a sleeve with a plurality of slots arranged in the longitudinal direction, wherein the slots are inclined relative to the radial direction in a sectional view perpendicularly to the sleeve axis.
Further advantages, features and possible uses of the present invention will be clearly apparent from the description hereinafter of preferred embodiments and the accompanying Figures
The post-treatment system according to the invention here comprises four post-treatment tools which each comprise a receiving plate 4, 4′, 4″, 4′″ and a pin plate 6, 6′, 6″, 6′″. The four treatment tools are fixed to a rotatable shaft 5 so that the four post-treatment tools can be moved into four different positions by stepwise rotation of the shaft 5 through 90°.
The position shown at the top in
The receiving plate 4 now moves with the received preforms towards the left again so that the preforms or the receiving cavities 2 are arranged exactly opposite the post-treatment pins 3 of the pin plate 9. The pin plate 9 can now be moved perpendicularly to the plate plane into the receiving cavities again. The actual post-treatment of the preforms is effected in that condition. While now the next group of preforms is being produced in the injection molding mold 9, the robot unit will rotate the shaft 5 so that another one of the four post-treatment tools comprising the pin plate 6 and the receiving plate 4 assumes the position shown at the top in
Here too the pin plate is moved out of the mold into the open position, and the receiving plate is again moved towards the right into the transfer position so that it is ready to receive the next group of preforms while the previous group of preforms still remains in the corresponding post-treatment tool. After repeated transfer of the next group of preforms and movement of the corresponding pin plate into the receiving plate 4 and further rotation of the shaft 5, the receiving tool with the first group of preforms 7 adopts at some time the position shown at the bottom in
The rotation of the shaft does not always have to be through 90°. Rather, the rotation can also be through a multiple of 90°, more specifically preferably in such a way that, after the shaft has rotated three times, the receiving tool which is next arranged in the readiness position is disposed in the removal position.
It will be appreciated that the withdrawal movement of the receiving plate can take place in a lateral direction synchronously with the lateral withdrawal movement of that receiving plate which is just in the readiness position so that one and the same drive can be used for that.
It will be clear that, in the embodiment according to the invention, just one pin plate is associated with each receiving plate, the post-treatment pins of which pin plate remain within the receiving cavities of the receiving plate throughout the entire post-treatment process.
As soon as the receiving plate 4 is within the injection molding mold 9 the preforms 7 which are already hardened at the outside are transferred into the receiving cavities 2 of the receiving plate 4. Then the receiving plate 4 is moved in the X-direction again, this time towards the left. The individual preforms 7 are now contained in the receiving cavities 2. As soon as the receiving cavities 2 are again arranged opposite the post-treatment pins 3 of the associated pin plate 6 the pin plate 6 is moved in the direction of the receiving plate 4 so that the post-treatment tool is closed. There now occurs a rotation of the shaft 3 through 90° so that the next post-treatment tool comprising the pin plate 6 and the receiving plate 4 assumes the corresponding readiness position to accept the next group of preforms with the injection molding tool 9 open. In the meantime post-treatment of the previous group of preforms takes place. As soon as the shaft 3 has now been rotated a total of three times through 90° the first post-treatment tool has reached the position shown at the bottom in
Then, as shown in
In the next step shown in
In
The described method is now repeated successively for all four post-treatment tools. It will be appreciated that, although hitherto embodiments with four post-treatment tools have been respectively described, embodiments with a different number of post-treatment tools can also be used. The only essential aspect is that at least two post-treatment tools are provided so that the preforms 7 can remain therein over a longer period of time which is markedly greater than the cycle time in the injection molding mold 9.
That condition is shown in
Finally
A post-treatment tool (in the illustrated example the uppermost post-treatment tool) is connected to a linear drive 15. By means of the linear drive the entire block of all post-treatment tools can be moved in one direction (in the illustrated example in the horizontal direction). The double-headed arrow shown in broken line is intended to denote the line of movement of a transfer device, by means of which the preforms are transferred from the injection molding mold into the post-treatment tools. As the preforms are to be transferred in succession into the respective post-treatment tools, the block of post-treatment tools can be displaced by means of the linear drive 15 in such a way that the post-treatment tool in question comes to lie directly in front of the line of movement of the transfer device. All post-treatment tools are carried on rails 14.
In addition each post-treatment tool has a stroke device 16, by means of which the respective post-treatment tool can be moved from the post-treatment position into the opened position.
The sequence of movements is now described diagrammatically with reference to
Finally
A gripper device 11 which here has a row of transfer cavities 18 and guide rails disposed therebetween can be moved both into the opened tool mold 9 and also into an opened post-treatment tool.
Now, as shown in
The gripper unit 11 is then moved out of the post-treatment tool and into the opened tool mold 9 so that a new group of preforms 7 can be transferred into the transfer cavities 18, as shown in
The gripper unit 11 then moves into the post-treatment tool again, in which case this time the transfer cavities 18 come to lie opposite the pins (
The plate 21 which adjoins at the right in
To save space the post-treatment pins are always arranged between the receiving cavities of the same plates. The plate shown at the right-hand end in
Each of the four post-treatment tools 19-1, 19-2, 19-3 and 19-4 shown in the example serves to receive and post-treat a set of preforms while the injection molding tool is already producing the next set of preforms.
The function of the individual post-treatment tools or the alternate fitment and removal of the preforms is shown in
After the post-treated preforms have been removed from the first post-treatment tool and the new set of preforms has been pushed on to the post-treatment pin the first post-treatment tool 19-1 is closed and the second post-treatment tool 19-2 is opened. The gripper plate 23 is now moved into a position so that the guide elements 17 come to lie opposite the post-treatment pins 3. The preforms are removed and slide along the guide elements 17 out of the post-treatment tool. That situation is shown in
All post-treatment tools can be successively fitted with preforms in the described fashion. When all post-treatment tools are fitted in that way, then, beginning with the first post-treatment tool, the post-treated preforms are removed and replaced by a fresh set of preforms.
As can also be seen from
The invention may be broadly discussed with specific reference to item numbers in the drawings as examples as follows:
As previously discussed, in accordance with the invention, a system is provided for the post-treatment of preforms (7) produced in an injection molding mold. The system includes at least two post-treatment tools each of which have its own receiving plate (4) which has a group of receiving cavities (2) and its own pin plate (6) which has a group of post-treatment pins (3), and
a device for transferring the preforms (7) out of the injection molding mold alternately into the at least two post-treatment tools,
wherein the pin plate (6) and the receiving plate (4) of each post-treatment tool are reciprocatingly movable relative to each other between an open position in which the post-treatment pins (3) are arranged outside the receiving cavities (2) and a post-treatment position in which the post-treatment pins (3) are arranged at least partially in the receiving cavities (2).
The receiving plate may at the same time be in the form of a pin plate.
In the system, the transfer device may be a gripper plate (1) with gripper elements (11) for gripping the preforms (7) in the injection molding mold and transporting the preforms (7) alternately to the at least two post-treatment tools and the transfer device has an ejection system having ejection elements with which the preforms (7) can be released from the injection molding mold so that by virtue of the force of gravity they can be transferred alternately into the at least post-treatment tools.
In an open position the pin plate (6) and the receiving plate (4) may be reciprocatingly movable laterally relative to each other between the open position in which the pins are in opposite relationship to the receiving cavities (2) and a transfer position in which the pins and the receiving cavities (2) are not in opposite relationship.
A robot unit may be provided for moving each post-treatment tool into a readiness position from which the post-treatment tool can be moved to an open removal position for accepting preforms (7) or can be moved to an open ejecting position for ejecting of preforms (7). The robot unit may be so designed that each post-treatment tool can be moved into a waiting position. The robot unit may include a rotational unit which is rotatable about an axis of rotation, wherein the receiving plates (4) are fixed to the rotational unit so that they can be moved from the readiness position into the removal position by rotation of the rotational unit.
When in the removal position, the post-treatment tool may be moved into an open position wherein the receiving plate (4) and the pin plate (6) are laterally movable in the open position relative to each other to an ejection position where the preforms (7) can be ejected from the receiving plate (4).
In the ejection position the ends of the receiving cavities (2) may be so arranged that the preforms can be ejected from the receiving cavities (2) because of their own weight.
The transfer position may be arranged inside or outside of the injection molding mold.
The pin plate (6) may have through openings, through which the preforms (7) can be introduced into and/or ejected from the receiving cavities (2).
Further, the pin plate (6) may have gripper elements (8), wherein a gripper element is associated with each receiving cavity (2) of the associated receiving plate (4) and the pin plate (6) and the receiving plate (4) are movable relative to each other laterally between two positions and are movable towards and away from each other in both positions so that in the one position the post-treatment pins (3) can be introduced into the receiving cavities (2) and removed again and in the other position the preforms (7) can be removed from the receiving cavities (2) by means of the gripper elements (8).
A positioning device may be provided for positioning a first of the post-treatment tools in at least one positioning direction, wherein the at least two post-treatment tools are connected together so that, with the positioning device for positioning the first post-treatment tool, at least one further post-treatment tool can be positioned by corresponding positioning of the first post-treatment tool.
At least one opening and closing device is provided for moving the pin plate (6) and the receiving plate (4) between the open position and a post-treatment position wherein preforms (7) are treated. The positioning device and the opening and closing device are preferably oriented in a mutually co-linear relationship. The positioning device preferably includes a linear drive.
Desirably, at least two post-treatment tools are arranged in mutually juxtaposed relationship in the positioning direction, wherein the receiving plate of a post-treatment tool is connected to the pin plate of another post-treatment tool, e.g. at least two post-treatment tools are arranged displaceably on rails.
An opening and closing device is provided that is preferably a linear operating device. An opening and closing device may be provided for
A guide element is preferably provided for guiding a preform out of the post-treatment tool which guide element, when the post-treatment tool is opened, can be moved between the receiving plate and the pin plate of the post-treatment tool. The guide element can be a substantially U-shaped rail. The guide element may be provided on the device for transferring the preforms from the injection molding mold into the post-treatment tools. There may be only one opening and closing device functioning for all post treatment tools or opening and closing devices may be provided for each of them.
At least one locking device is preferably provided which in a locked position prevents opening of a corresponding post-treatment tool.
Preferably, the post-treatment tools are arranged in a row in mutually juxtaposed relationship in the positioning direction, the positioning device engages a first post-treatment tool of the row and the opening and closing device engages a last post-treatment tool of the row, so that by actuation of the positioning device the row of post-treatment tools can be positioned and by unlocking of the locking device for a post-treatment tool and locking of the locking device for all other post-treatment tools of the row and actuation of the opening and closing device, a post-treatment tool can be opened.
The post-treatment tools may be arranged in succession in the opening direction, wherein preferably the post-treatment pins and the receiving cavities of two adjacently arranged post-treatment tools are displaced relative to each other by approximately half the spacing of two adjacent receiving cavities of a receiving plate.
The at least two post-treatment tools each additionally may have a bottom plate with a group of bottom post-treatment devices and the receiving cavities are open on both sides. The bottom post-treatment devices may, for example, include a nozzle with which cooling fluid can be directed on to the bottom of the preform.
A single plate may at the same time be the bottom plate of a first post-treatment tool, the receiving plate of a second post-treatment tool and the pin plate of a third post-treatment tool.
The receiving plate desirably has a feed means for a cooling fluid, wherein the feed means for cooling fluid is so arranged that cooling fluid can be passed into each receiving cavity.
Further, the receiving cavities desirably have two open sides and the feed means for cooling fluid is so arranged that the cooling fluid is divided and leaves the receiving cavity at both open sides. The feed means for cooling fluid may have a swirl element which is so designed that it imparts a circular rotational movement to the cooling fluid.
The swirl element may for example include sleeve with a plurality of slots arranged in the longitudinal direction, wherein the slots are inclined relative to the radial direction in a sectional view perpendicularly to the sleeve axis.
The invention, as previously discussed further includes a method of post-treatment of a preform (7) produced in an injection molding mold, wherein the preform (7) is transferred out of the injection molding mold into a receiving cavity (2) whose internal shape substantially corresponds to the external shape of the preform (7), wherein a post-treatment pin (3) whose external shape substantially corresponds to the internal shape of the preform is introduced into the preform (7) and remains there for a period of time which is longer than the mold stand time of the injection molding mold.
The preform (7) is desirably prevented from coming into contact with the internal surface of the receiving cavity (2) by means of a fluid, e.g. a gas, which is introduced into the receiving cavity (2) through an opening in the receiving cavity (2). The fluid may be at least at times into the preform (7) through an opening in the post-treatment pin (3).
The fluid may also be introduced into the preform (7) in such a way that the preform (7) is pressed further into the receiving cavity (2) by the fluid as it flows out and substantially without direct contact between the post-treatment pin (3) and the preform (7).
In the method, as previously discussed, the receiving cavity may have two open ends and fluid is introduced into the receiving cavity in such a way that the fluid flows along the outside of the preform and issues from both ends of the receiving cavity.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2005 057 466.1 | Nov 2005 | DE | national |
| 10 2006 028 725.8 | Jun 2006 | DE | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/EP2006/068363 | 11/10/2006 | WO | 00 | 3/12/2009 |
