The present invention refers to apparatus for injection moulding of plastic materials including a mould comprising a distributor of plastic material to be injected, at least one injector including a nozzle with respect to which a valve pin is moveable, and actuator means for controlling the displacement of the valve pin between a closing position and an opening position to enable the flowing of the pressurised fluid plastic material from the distributor to the mould cavity.
Conventionally, actuator means for controlling the valve pin of the or of each injector consist in fluid actuators which entail considerable complications due to the need of providing dedicated systems and pipings for supplying oil and air, as well as almost zero control options except for an ON/OFF actuation. In addition, there are problems related to cleaning, and overall dimensions due to the presence of the pipings.
Actuation systems employing electric motors, in particular of the rotary type, and provided with devices for detecting the position of the valve pin, for example an encoder or resolver associated to the shaft of the rotary motor and connected to a stand-alone electronic unit by means of which a prompt and precise control of the position, speed and acceleration of the valve pin is carried out, were proposed with the aim of overcoming these drawbacks. The electronic unit is usually provided separately with respect to the mould and it is designed to be indistinctly combined with any mould provided with electric actuators, regardless of the number thereof.
However, the undeniable advantages in terms of flexibility and precision in controlling the moulding process have a negative impact on the supply and operating costs of the equipment and the overall dimensions in the work area. Examples regarding this are described and illustrated for example in the European patent applications numbers EP-2679374A1, EP-2918389A1 and EP-3009251A1, all on behalf of the Applicant. In the concrete application of the solutions described in these documents, whose costs are high and considerably higher than those of fluid actuators, the rotary electric motors are of the alternating current type provided with an encoder or resolver and combined with a stand-alone electronic unit.
In order to partly overcome these drawbacks, the Applicant proposed a simpler, more cost-effective and less cumbersome alternative to the prior art systems with the aforementioned electric motors, while maintaining the undeniable advantages with respect to systems with fluid actuators in terms of construction simplicity of the apparatus, cleaning and possibility of adjusting the main opening and closing parameters of the single injector.
In such proposal, described and illustrated in the international patent application WO2017098345 in the name of the Applicant, the power supply and control unit is fixed to the mould and uniquely associated thereto. The supply and control unit is preferably fixed to the fixing plate of the mould and the electrical supply is provided by means of connectors located on the unit, while the control of the main parameters for opening and closing the injectors occurs by suitably controlling the driver of the circuit board associated to each electric motor and positioned in the unit.
This configuration is schematically represented in
The configuration of the main parameters is carried out by the operator for example by means of an outer universal control panel 9 (e.g. PLC), that can be used for configuring the drivers 5 for example by means of appropriate connection to the memory connector 10 present on the power supply and control unit 3.
This enables at least partly obtaining the advantages of the electric motors provided for in the aforementioned prior art solutions, but eliminating the use of a stand-alone electronic control unit, thus cutting costs considerably and reducing the overall dimension in the work area.
The costs still remain considerably high given that every mould is actually provided with its own control unit 3 complete with all the elements (e.g. circuit boards, drivers 5, memory 4, memory 10 and power supply 7 connector), though small in size and smaller overall dimensions with respect to the stand-alone electronic unit.
The overall dimensions of the unit fixed to the mould 1 can give rise to problems in some cases during the step of transporting and installing in the dedicated moulding press.
Furthermore, there is no advantage in terms of time for the operator, given that there still arises the need for configuring the main parameters suitably controlling the circuit board driver 5, prior to staring the moulding process.
DE-102004052499 generally discloses an injection molding tool with electronic control module wherein a data storage unit of molding parameters is secured to the mold and is connected via a communication interface to a control unit of the injection apparatus.
The object of the present invention is to further reduce the costs, overall dimensions and start-up times of the moulding apparatus.
This object is attained according to the invention mainly due to the fact that part of the power supply and control unit, with particular reference to the electric motors control drivers, is not fixed to the mould, while another part of the power supply and control unit, specifically at least one part of the memory, is separated from the drivers and it is fixed to the mould. This part of memory can serve as an “identity card” of the mould.
Thus, the invention enables providing an independent control unit containing the drivers having the advantage lying in the fact that it can be combined with many different moulds.
In this manner, the purchaser of the moulding apparatus will need to be equipped with only one of these independent control units for all electrical actuation systems in his possession, thus saving on buying a considerable number of drivers which account for the highest costs of the control unit according to the prior art.
In the attached drawings provided by way of non-limiting example:
In both embodiments of the invention exemplified in
According to the first embodiment of the invention schematised in
In particular all moulds that use electric motors for displacing the obturators already provide for a safety interface box to be combined with the moulding press. Thus, the drivers 5 could be inserted into the safety interface box, or into a further independent box.
Alternatively, the moulding press 2 of the apparatus could be directly provided with drivers 5, integrated in the control unit thereof. For example, let us consider an electrical actuation moulding press provided to be combined with a system for actuating the obturators of the injectors (electrical too): thus, an all-electric system that is easy to manage can be created according to the invention.
In a preferred solution visible in
As mentioned, this new independent unit containing the drivers 5 is not sufficient to guarantee the proper actuation of the electric actuators in the mould. As a matter of fact, the primary memory 4 containing the instructions for controlling the main parameters for opening and closing the injectors, to be carried out by the drivers 5, is also required.
According to the first embodiment schematised in
According to a further possibility, the memory 4 containing the instructions regarding each electric motor for actuating the obturator of the respective injector, is integrated in the electric motor.
Connecting the independent box containing the drivers 5 to the memory 4 fixed to the mould 1 by means of special control 8 and memory 10 connectors, the drivers 5 automatically download the specific instructions to be followed by the respective electric actuators, without requiring any intervention or configuration by the user, thus saving time considerably. The instructions could for example have been previously uploaded in the memory 4 by the supplier of the injection apparatus, so as to deliver the system to the customer already ready for connection to the drivers and thus made operative automatically.
The instructions can be set in the memory automatically, for example by transferring the results of a dynamic software simulation (for example the one referred to as “MoldFlow®”) by means of a special external medium (USB flash drive, SD card, etc.) to the memory 4.
Alternatively, the instructions can be set in the memory manually, for example through a human-machine interface (HMI) such as a control panel 9 (e.g. PLC) integrally joined to the box of the memory as observable in
According to an advantageous alternative visible in
Alternatively, the manual setting could be carried out by means of electronic devices such as PCs, tablets or smartphones using a dedicated software.
In this case too, the electronic device can be disconnected at the end of the setting without jeopardising the functionalities. According to a further alternative, the instructions can be uploaded directly from the control panel of moulding press 11, still through suitable connection with the primary memory 4.
The purchaser of the moulding apparatus may obviously be allowed to change the instructions or enter new ones into the memory using one of the methods described above.
Furthermore, the instructions can be transferred from one system to another for example by means of an external medium (e.g. USB flash drive, SD card, etc.) and a special communication port provided for on the box of the primary memory 4 or on the panel of the moulding press 11.
The second embodiment, schematised in
In particular, the memory 4 supplied to the purchaser of the moulding apparatus will be provided already containing—therein—a high number of different pre-set instructions, designated for different injection systems.
In order to combine the specific hot channel injection system (and thus the specific mould) with the correct moulding instructions, there is provided a secondary memory 6 fixed to the mould 1, basically corresponding to a recognition device (e.g. an electronic chip, radio-frequency identification—“RFID”—tag, etc.) applied on the mould (e.g. on a plate, on a wiring structure, on a single motor).
Connecting the independent box containing the primary memory 4 and drivers 5 to the secondary memory 6 fixed to the mould 1, enables automatically combining the specific injection system (mould) with the correct moulding instruction from among the many stored in the primary memory 4.
This embodiment enables cutting costs further, given that the primary memory 4 and drivers 5 are common to several injection systems, besides a further reduction of the overall dimensions on the mould, given that all that is required is to provide the secondary memory 6 and the relative connection 8 and memory 10 connectors.
When setting the instructions in the primary memory 4 (external in this case) by the supplier or the user, all options described above regarding regarding the first embodiment shall apply.
The connection of the independent external box with the primary memory 4 or the secondary memory 6 fixed to the mould 1, occurs by means of the connectors 8 for connecting to the motors and respective encoders or resolvers used in the systems according to the prior art, in particular those providing for the use of a stand-alone electronic control unit.
In this manner, the user can at any time pass to a more advanced, flexible and precise system that enables setting further parameters or displaying further results (but with a considerably higher cost and overall dimension).
According to an advantageous characteristic, the external independent box containing the drivers 5 and possibly the primary memory 4 can be modular, so that it can be potentially combined with injection systems with different characteristics, in particular depending on the number of electric motors.
Furthermore, a single driver can be combined to one or more electric motors.
Just like in the prior art, the start input of the moulding cycle preferably comes from the control panel of the moulding press 11 or from a conventional sequential control unit. Upon receiving the input, the drivers 5 control the electric motors according to the instructions downloaded from the primary memory 4.
To summarise, the distinctive characteristics of the invention can be summarised as follows:
Position of the drivers 5:
Position of the memory (primary 4 and/or secondary 6) fixed to the mould 1:
Configuration of the memory 4 (by supplier or by user):
Types of motors that can be used (brushless, asynchronous, etc.) and operating mechanism (drive, screw-holder nut, etc.) according to the prior art (PCT/IB2016/056168).
The advantages arising from the invention as compared to solutions provided for in the prior art (stand-alone power supply and control unit; power supply and control unit fixed—in its entirety—to the mould) can be summarised as follows:
Obviously, the construction details and the embodiments may vary with respect to what has been described and illustrated by way of example, without departing from the scope of protection of the invention as described in the claims that follow.
Number | Date | Country | Kind |
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102017000062960 | Jun 2017 | IT | national |