WO2009150052A1

WO2009150052A1 - Handling apparatus for an injection-moulding machine and method for operating the same

Info

Publication number: WO2009150052A1
Application number: PCT/EP2009/056445
Authority: WO
Inventors: Thomas ZÜGER; Dominik Gunsch; Eric Schmidheiny
Original assignee: Netstal Maschinen Ag
Priority date: 2008-06-09
Filing date: 2009-05-27
Publication date: 2009-12-17
Also published as: DE102008027472B3

Abstract

The present invention relates to a handling apparatus for a plastics-injection-moulding machine, and also to a method for operating the same. The handling apparatus comprises a removal apparatus (10) with a number n of retaining apparatuses (12) with which products produced in a mould of the injection-moulding machine can be removed from the mould, a transfer apparatus (14) and an after-cooling device (20), where the removal apparatus (10) is movable to and fro at least between two positions, and in a first position, in an opened mould, can accept the plastics products from the mould, and in a second position, having moved out of the mould, can transfer the plastics products to the transfer apparatus (14), and the transfer apparatus (14) is likewise movable between at least two positions, and in its first position takes the plastics products from the removal apparatus (10), and in a second position transfers the plastics products to the after-cooling unit (20). In order to shorten the movement sequence, it is proposed that the transfer apparatus (14) tracks linearly to and fro between the removal apparatus (10) and the after-cooling device (20), where the tracking movement facilitates the transfer of the plastics products both from the removal apparatus (10) to the transfer apparatus (14) and from the transfer apparatus (14) to the after-cooling device (20), and that, in a position between the removal apparatus (10) and the after-cooling device (20), the transfer apparatus (14) is rotated around an axis.

Description

description

title

Handling device for an injection molding machine and method for operating the same

The present invention relates to a handling device (also called actuator) for an injection molding machine according to the preamble of claim 1 and a method for its operation.

In the manufacture of plastic products with an injection molding machine, the parts formed in the cavity of a mold must be removed from the opened mold after the injection and curing process. This is unproblematic in the case of many plastic products or production processes since sufficient time is available for curing and cooling the plastic products in the mold, so that the plastic products thus produced can be easily removed after opening with a commercially available robot arm or ejected onto a conveyor belt.

However, there are applications in which it is necessary to remove as quickly as possible the plastic products produced by the injection molding machine and, moreover, to cool intensively in order to avoid negative qualitative effects. One example of this is the production of PET preforms - also referred to as preforms in the following - which are removed from the molds in a very hot state. If no suitable handling and aftercooling device is provided, these products deform and, in addition, the material can crystallize out, which leads to a broke part.

Especially in the production of preforms, a short cycle time is required due to the desire for high productivity. One cycle means a complete production step to produce a batch of n

Preforms according to the number of mold cavities in the mold. So far Molds with up to 200 mold cavities (cavities for these preforms) are used. With cycle times of less than 10 seconds, savings in the seconds range mean productivity increases of more than 10%.

Cooling time is a determining factor for the total time of a full cycle. The main cooling power still takes place in the mold itself. Both mold halves are intensively water-cooled during the casting process, so that the temperature of the preforms can still be reduced in the form of about 280 ° at least in the boundary layers to a range of 80-130 °. In this case, the so-called glass transition temperature of about 140 ^° C. is passed through very quickly in the outer layers. The actual casting process up to the removal of injection molded parts has been greatly reduced in the recent past. This with optimal qualities in relation to the still semi-rigid preforms. The preforms must be so strong in the mold halves that they can be handled with relatively large forces from the ejectors and transferred without deformation or damage to a sampling device.

In Fig. 2, a first system of the prior art for the production of preforms of the applicant is given, as shown in WO 2004/041510. Based on this Fig. 2, the manufacturing process can be shown. Thus, in this plant 100 for the production of preforms, a PET granulate from a plasticizing and injection device 112 is melted and injected into the plurality of mold cavities of the mold 124, 126. In Fig. 2 while the arranged on a machine bed 110 together with the plasticizing and injecting 112 closing unit 114 is shown, which is shown purely schematically and presently consists of a support plate 118, the fixed platen 116 and the movable platen 120, wherein between the fixed clamping plate 116 and the spacer plate 118 four pull members 122 extend in the form of spars on which the movable platen 120 is guided. On the movable platen, the first mold half 124 and on the fixed platen 116, the second platen 126 is arranged. The first platen 124 includes a number of n core elements 128, each with corresponding cavity elements of the second platen 126 in the closed state form a total of n mold cavities. 2, the locking device 114 is shown in the open state. In the closed state, molten PET material is injected at 280 ° C, with immediate intensive water cooling takes place in the molds. However, the desired 80 - 130 ⁰ C can not be achieved uniformly throughout the cross section of the preforms. The consequence is that, seen in the material cross-section, rapid re-heating would take place if intensive water cooling is interrupted. As a result, the postcooling is of considerable importance. First, form changes to the dimensionally stable state of storage, but also surface damage, such as bruises, etc. are avoided. Second, it must be prevented that the cooling takes place too slowly in higher temperature ranges and z. B. set by the reheating locally harmful crystal formations. The goal is a uniform amorphous state in the material of the finished preforms. The residual temperature should be so deep that in the relatively large packaging containers with thousands of loose poured parts at the points of contact no adhesion damage. Therefore, the injection-molded parts may not exceed a surface temperature of 40 ⁰ C even after slight reheating. The post-cooling after removal of the preforms from the injection molds according to the prior art of FIG. 2 is as follows:

When the mold is open-as shown in FIG. 2-a removal gripper 130, which has a number n of cooling sleeves 132 corresponding to the number of core elements 128, is retracted into the opened mold and takes over the preforms from the core elements 128 into the respective cooling sleeves 132. After this transfer, the removal gripper is moved out of the molding tool into a second position by means of a corresponding drive (dashed representation). In this position, a transfer gripper 140 is positioned in front of the removal gripper 130 such that a number of pins 142 corresponding to the cooling sleeves are each aligned with an associated preform, so that each preform accommodated in a cooling sleeve 132 of the removal gripper can be transferred to an opposite pin 142 , Subsequently, the transfer gripper 140, as shown in Fig. 2, pivoted by 90 °. About the transfer gripper 140 is a movable After-cooling device 150 is positioned, and then the preforms can be handed over. In this case, the Nachkühleinrichtung 140 an even multiple of the number n of corresponding preforms, so that several batches of preforms can be transferred to the Nachkühleinrichtung, which ensures a particularly intensive and long cooling. After each transfer, the aftercooler 150 travels via a conveyor belt 160 (see dashed line illustration in FIG. The longest cooled batch of preforms 105 are then cyclically ejected from the after-cooling device 150, which has been moved over the conveyor belt 160, and fed to the packaging by means of the conveyor belt 160.

Another embodiment of a known preform handling device is known from US RE33,237. In this case, just as in the embodiment in Fig. 2 with a plasticizing and injection device 210, a PET material is injected into the mold cavity of a closed mold. Again, the mold halves 224 and 226 are received by a fixed platen 222 and a movable platen 220, wherein the movable platen 220 is supported against a support plate 218. In contrast to the embodiment described in FIG. 2, the extraction device 230 simultaneously serves as a post-cooling unit and can preferably accommodate a plurality of batches of preforms. In the operation of this second device, the preforms are first produced in a closed mold and after a corresponding cooling, the closing unit 200 is opened. Subsequently, the removal and Nachkühleinrichtung 230 moves over the Bewegungsmimik 234 between the mold halves 224 and 226 and takes over the still hot preforms. After this acquisition, the removal and Nachkühleinrichtung 230 moves out of the mold and throws an already correspondingly cooled batch of preforms on a conveyor belt 236 from. Since, as shown in FIG. 3 b, the removal and aftercooling device comprise an even multiple of the number n of cooling sleeves, a plurality of batches of preforms can be received in the present case so that the preforms can remain in the removal and cooling device 230 over a plurality of cycles . before they are dropped. This time is enough for a corresponding cooling.

However, both of the devices described in FIGS. 2 and 3 have system-inherent disadvantages.

Thus, the device with transfer gripper in the embodiment of FIG. 2 performs eight sequential movements during one cycle, namely the movements back and forth removal grippers pivoting transfer gripper swivel back and forth, forward cooling device in the direction of the transfer position and the lowering and raising of the cooling block. With this movement, you can not undercut a certain dry-time. A further reduction of the dry-running time would only be possible with more powerful drives. However, these are expensive on the one hand, on the other hand, the transfer gripper can not be arbitrarily accelerated and decelerated, because the preforms can not be kept otherwise. Larger drives also cause more costs during operation, as a larger inverter must be used, which works with a certain power loss. With larger motor / inverter units, the absolute power dissipation also increases.

Object of the present invention is to provide a handling device and a method for their operation, with which the cycle time can be further reduced energy efficient.

This object is achieved by the features mentioned in claims 1 and 14.

An essential feature of the present invention resides in the fact that a transfer gripper can be moved linearly back and forth between the removal device and the post-cooling device, with both the transfer of the plastic products from the removal device to the transfer device and from the transfer device to the post-cooling device through the transfer device Movement along the path is supported. Moreover, the transfer gripper is rotatable about an axis in a position between the picking gripper and the cooling device, this axis being oriented perpendicular to the web. With this movement, steps can be saved, resulting in a significant gain in time. In particular, it is possible with the movement of the transfer device along the predetermined path to position both the receiving devices of the transfer device with respect to the products located in the removal device as well as the products held with the receiving devices with respect to the receptacles of the Nachkühlseinrichtung for each transfer, so for this purpose no own movement step is required.

On the transfer device, in particular on a plate, a number n of receiving elements may be provided on one side, which correspond to the number of holding devices of the removal gripper. In this case, this page is turned by rotation of both the removal device and the Nachkühleinrichtung. Alternatively, two opposite sides of the transfer gripper can each have n receiving elements, wherein in turn each side can be turned by rotation of both the removal device and the post-cooling device. The last alternative halves the number of turns required to transfer the preforms.

The absorption capacity of the post-cooling device preferably corresponds to an even multiple of the number n of the holding device in the removal device. In this case, two or more batches of preforms may be simultaneously received in the post-cooler, allowing the cooling time to be correspondingly extended.

For example, the post-cooling device may comprise two or more plates, each of which can hold a number n of manufactured plastic products and are rotatable about an axis, whereby each plate is optionally associated with the transfer device. According to a particularly preferred embodiment, four plates are arranged cubic to each other. In this case, each plate can receive a batch n of preforms so that the total capacity of the post-cooler in this embodiment represents four batches. After each transfer of a batch of preforms from the transfer gripper to the Nachkühleinrichtung the Nachkühleinrichtung is subsequently rotated by 90 °, before the rotation of the longest in the Nachkühleinrichtung charge of preforms is dropped onto a conveyor belt, so that in a subsequent rotation again an empty Plate is associated with the transfer device.

For receiving preforms, the holding devices on the removal gripper are preferably sleeve-shaped and / or the receiving elements on the transfer gripper are designed as pins. These pins are preferably formed with a channel so that they can blow out air or attract air together with a corresponding blowing or vacuum device. This can be ensured in particular a safe transfer (blowing air) and safe transport (generation of negative pressure by removing air and thus holding the preforms on the pins).

A preferred embodiment of the present invention will be explained below with reference to the accompanying drawings. The drawing shows in

Fig. 1 is a schematic representation of an inventive

Handling device

Fig. 2 is a schematic representation of a plant for the production of PET preforms according to the prior art and

3a and 3b is a schematic representation of a second plant for the production of PET preforms according to the prior art. In the handling device according to the invention, as shown in Fig. 1, only a removal gripper 10, a transfer gripper 14, a Nachkühl- device 20 and a conveyor belt 26 is shown. However, such a device can be readily implemented in a plant, as explained in Fig. 2 in the introduction.

The removal gripper 11 has a plate with a number n of cooling sleeves 12, in which preforms can be accommodated. The removal gripper can be moved by means of a movement mimic 11 with a drive not shown in two positions (see arrows).

Between the removal gripper 11 in its second position shown in FIG. 1 and the aftercooling device 20, the transfer gripper 14 is provided, which in the present case essentially consists of a plate, on the two opposite sides of which a number n (batch) of pins 16 are arranged. namely, corresponding number of cooling sleeves 12. These pins 16 (also called pins) are shown only schematically and have a central inner channel through which - blown or sucked together with a blower or suction device not shown -. The transfer gripper 14 can be moved back and forth linearly between two end positions via a movement mimic 18, as indicated by the two arrows pointing to the right and left in the movement mimic. In addition, the transfer gripper 14 is formed completely rotatable about a central axis.

On the opposite side of the removal gripper 10 of the transfer gripper 14, a Nachkühleinrichtung 20 is arranged, which in the present case consists of four cooling plates 22 which are arranged cube-shaped about an axis of rotation 24. By means of a corresponding drive (not shown), this cube consisting of the cooling plates 22 can be rotated counterclockwise (see FIG. In this case, a plate 22 can alternately be aligned with the transfer gripper 14. Each cooling plate 22 of the post-cooling device 20 comprises a number n (batch) of cooled receptacles for PET preforms. Below the aftercooler a conveyor belt 26 is arranged. During operation of this handling device, the procedure is as follows:

In the embodiment according to the invention, the removal gripper 10 equipped with a number n (charge) cooling sleeves moves into the opened molding tool via a movement mimic 11 and takes over the preforms from the core element assigned to each cooling sleeve 12 in a manner known per se. After the takeover, the removal gripper 10 moves out of this position designated as position 1 out of the molding tool into a second position, which is shown in FIG.

Subsequently, the transfer gripper is moved on its path so far in the direction of the removal gripper 10 that the pins 16 of the right side of the transfer gripper 14 at least partially retract into the preforms held in the cooling sleeves 12. Subsequently, the preforms are transferred to the pins 16 of the transfer gripper 14. This transfer can be assisted by a blowing impulse on the sides of the cooling sleeves as well as by a suction impulse on the side of the pins 16 of the transfer gripper 14.

Subsequently, the transfer gripper 14 is moved with its musculoskeletal system (mimic 18) linearly in the direction of the Nachkühleinrichtung 20 and approximately centrally performs a rotation through 180 ° about its axis of rotation 28 (see, rotation arrow in Fig. 1). At the end of its movement or on the last part of the way, the transfer gripper 14 at least partially pushes the preforms into the receiving sleeves of the plate facing the transfer gripper and thus transfers the preforms to the receiving sleeves of the cooling plate 22 shown on the right in FIG 14 then returns to its original position or immediately returns to the transfer position, where he can take over a new batch of preforms from the removal gripper 10. In this case, the other side of the pins 16 is now assigned to the removal gripper 10, so that a repeated rotation during the process can be omitted. Subsequently or simultaneously with the return process of the transfer gripper 14 in the direction of the removal gripper, the cooling device is rotated about the axis 24 by 90 ° so that the preforms just transferred are now in the upper plate 22. Before twisting, however, still in the lower plate 22 located preforms 22 are dropped onto the conveyor belt 26, so that this plate 22 is now taught and can be assigned to the removal gripper by the already mentioned rotation. Overall, there are thus always three batches of preforms in the post-cooler 20.

With the present invention, the cycle time decisive masses of the handling device, namely that of the fast-moving removal gripper and transfer gripper can be kept as small as possible. Moreover, the number of movements for the transfer gripper within the machine cycle can be kept low, especially when using a double-sided transfer gripper. For the adoption of different Preformlängen the stroke of the longitudinal movement of the transfer gripper in both directions can be adjusted accordingly. In the production of preforms in which the movement times of the post-cooling unit are not decisive, the transfer gripper can also be equipped on one side. In this case, however, there is still another rotational movement, in which the transfer gripper in turn must be turned off the removal gripper.

Overall, the present invention offers in comparison to the previous Nachkühleinheiten shown in FIG. 2, the advantage of a smaller number of axes of movement, the large masses (Nachkühlsystem) must not be cyclically decisive moves. The corresponding movement of the Nachkühleinheit is parallel to other movements. Moreover, since the heavy post-cooling device does not have to be moved in a cycle-time-determining manner, this results in a better energy balance. Also, the preforms are always thrown over the same position of the conveyor belt, so that existing technologies for forwarding the preforms can continue to be used. Since the center of gravity of the moving and rotating masses is as close as possible to the point of the force influence, only small moments in the transfer gripper must and the Nachkühleinrichtung 20 are held. Moreover, when transferring the preforms from the transfer gripper to the recooling device, it is not necessary, as in the case of the embodiment in FIG. 2, to work against the gravitational field, so that the transfer gripper may also be able to dispense with operation with compressed air. When ejecting the preforms from the Nachkühleinrichtung this process is in turn supported by the gravitational field.

LIST OF REFERENCE NUMBERS

removal gripper

actuating arm

cooling sleeves

transfer gripper

retaining pin

movement facial expressions

after-cooling

cooling plate

Rotary axis of the Nachkühleinrichtung

conveyor belt

Rotary axis transfer gripper

First plant for the production of PET preforms from the state of the art

technology

Preforms / Preforms

machine bed

Plasticizing and injection unit

closing unit

Fixed platen

support plate

Movable mold clamping plate

Holme

First mold half

Second mold half

Core elements of the first mold half

removal gripper

cooling sleeves

transfer gripper

retaining pins

after-cooler

conveyor belt

Second plant for the production of PET preforms from the state of the art technology

210 plasticizing and single-use unit

214 closing unit

218 support plate

220 Movable mold clamping plate

222 Fixed platen

224 First mold half

225 core elements

226 Second mold half

230 removal and cooling device

231 cooling sleeves

232 Support for removal and cooling device

234 Movement facial expressions for removal and cooling device

236 conveyor belt

Claims

claims

1. Handling device for a plastic injection molding machine comprising

a removal device (10) with a number n of holding devices (12) with which plastic products produced in a molding tool of the injection molding machine can be removed from the molding tool,

a transfer device (14) and

- A Nachkühleinrichtung (20) wherein

- The removal device (10) at least between two positions back and forth is movable, in a first position in an open mold, the plastic products can absorb from the mold and in a second herausmaschinenen from the mold position the plastic products to the transfer device (14 ),

- The transfer device (14) is also movable between at least two positions, in its first position, the plastic products of the removal device (10) takes over and in a second position, the plastic products to the Nachkühleinheit (20) passes, characterized in that the transfer device (14) between the removal device (10) and the Nachkühleinrichtung (20) on a path back and forth, wherein both the transfer of the plastic products from the removal device (10) to the transfer device (14) and from the transfer device (14) for Nachkühler (20) is supported by the movement along the track, and that the transfer device (14) is rotatable in a position between the removal device (10) and the post-cooling device (20) about an axis which is at least substantially aligned perpendicular to the web.

2. Handling device according to claim 1, characterized in that the transfer device (14) comprises a plate on one side of a number n of receiving elements (16) are provided, each of which can receive a plastic product, wherein one side by rotation of both Removal device (10) as well as the Nachkühleinheit (20) is zuwendbar, where- by with the receiving elements (16) one side of the Tra

Device transported plastic products are receivable or deliverable.

3. Handling device according to claim 1, characterized in that the transfer device (14) comprises a plate, on whose two opposite sides in each case a number n of receiving elements (16) are provided which can each receive a plastic product, each side by rotation both the removal device (10) as well as the Nachkühlein- unit is zuwendbar, so that with the receiving elements (16) of each side alternately conveyed by the transfer device (14) plastic products are receivable or deliverable.

4. Handling device according to one of the preceding claims, characterized in that the absorption capacity of the cooling device (20) corresponds to an even multiple of the number n of the holding devices (12).

5. Handling device according to claim 4, characterized in that the Nachkühleinrichtung (20) with at least two plates (22) is formed, which are each formed for receiving at least the number n of the batch-produced plastic products and are rotatable about an axis of rotation.

6. Handling device according to claim 5, characterized in that the Nachkühleinrichtung (20) comprises four plates (22) which are arranged in a cubic shape.

7. Handling device according to one of the preceding claims 5 or 6, characterized in that the axes of rotation for the transfer device (14) and the axis of rotation (24) for the Nachkühleinrichtung (20) are aligned parallel to each other.

8. Handling device according to one of the preceding claims, characterized in that below the Nachkühleinrichtung (20) a transport device (16) is provided or can be arranged.

9. Handling device according to one of the preceding claims, characterized in that the holding devices (12) of the removal gripper (10) are sleeve-shaped for receiving in each case a plastic product.

10. Handling device according to claim 9, characterized in that the sleeve-like holding devices (12) are coolable.

11. Handling device according to one of the preceding claims, characterized in that the receiving elements (16) are pin-shaped.

12. Handling device according to claim 11, characterized in that means are provided to blow through the pin-shaped receiving elements (16) air and / or to suck air.

13. Handling device according to one of claims 9 to 12, characterized in that means are provided to blow through the sleeve-like holding devices air and / or to suck air.

14. A method for operating the handling device according to one of the preceding claims 1 to 13, characterized in that

- The removal device is moved between the open mold halves in the first position and a number of n plastic products from the Mold receives,

the removal device moves out of the position between the opened mold halves into the second position,

the transfer device is moved along the predetermined path to the first position and receives the n plastic products from the removal device,

that the transfer device travels on the predetermined path to a position between the removal device and the post-cooling device and is then rotated about an axis which is perpendicular to the direction of travel,

- The transfer device is further linearly moved to the Nachkühleinrichtung and passes the n plastic products to the Nachkühleinrichtung and

- That the transfer device is moved back towards its first position.

15. The method according to claim 14, characterized in that in a transfer device having only on one side holding devices (12), the transfer device on the way between Nachkühleinrichtung (20) and removal device (10) is in turn rotated.

16. The method according to claim 14 or 15, characterized in that the rotation is performed in each case by 180 °.

17. The method according to any one of claims 14 or 15, characterized in that after each transfer of the n plastic products from the transfer device to the Nachkühleinrichtung latter is rotated, whereby the transfer device is zuortbar in the next step of a previously emptied plate.

18. The method according to claim 17, characterized in that the plastic products of a plate of the post-cooling device are simultaneously dropped on a conveyor belt against rotation.