DE102021102557A1 - manufacturing plant - Google Patents

Abstract

The invention relates to a production plant (1) comprising at least one plastics processing machine (2) and an energy supply (3). In order to design such a production plant in such a way that an improved and ecological energy supply is possible, the invention provides that the energy supply (3) comprises: an AC network (4) which is connected to a DC network (6) via a converter (5). , and a direct current source (7) which is connected to the direct current network (6), the plastics processing machine (2) being able to be connected to the direct current network (6) in order to be supplied with electrical energy from it.

Description

The invention relates to a production plant comprising at least one plastics processing machine and an energy supply.

The efficient supply of energy to plastics processing machines and in particular to injection molding machines is a relevant task, particularly from the point of view of environmental compatibility. Such machines often have variable-speed drives. The machines are designed for connection to AC networks. The AC network feeds a DC intermediate circuit via a converter (ie rectifier), from which the machine is then supplied with energy. Such a solution is from EP 2 276 165 B1 known.

In plastics processing machines and in particular in injection molding machines with variable-speed drives, the conversion from alternating current to direct current in the frequency converters results in disadvantageous properties, with conversion losses in the rectifiers being particularly noteworthy; Furthermore, the non-sinusoidal current draw causes impairments in the mains supply quality and, under certain circumstances, also problems with electromagnetic compatibility as well as additional losses or loads in the lines.

The invention is based on the object of developing a production plant with a plastics processing machine, in particular with an injection molding machine, in such a way that an improved and ecological energy supply is possible. Measures should also be proposed as to how optimal energy supply is possible when regenerative energy sources are not available to the required extent. Furthermore, the above problems should be avoided.

The solution to this problem by the invention is characterized in that the energy supply of the production plant comprises: an AC network which is connected to a DC network via a converter, and a DC source which is connected to the DC network, with the plastics processing machine being able to be connected to the DC network is to be supplied from this with electrical energy.

The direct current source is preferably a photovoltaic system. The DC network can preferably be connected to an energy store (battery).

The plastics processing machine preferably has at least one variable-speed drive.

The plastics processing machine preferably has a direct current intermediate circuit which can be electrically connected to the direct current network via a connection module.

The plastics processing machine preferably has at least one heating element, which can be supplied with energy from the DC intermediate circuit via a semiconductor switching element, in particular by a bipolar transistor with an insulated gate electrode (insulated gate bipolar transistor, IGBT).

• - dass die Kunststoffverarbeitungsmaschine mindestens einen Verbraucher aufweist, der mit Wechselstrom betreibbar ist, und
• - dass die Gleichstromquelle und/oder der Energiespeicher mit einem Bestimmungs- oder Messelement in Verbindung steht, mit dem die Verfügbarkeit von Gleichspannung aus der Gleichstromquelle und/oder dem Energiespeicher gemessen werden kann,

wobei das Bestimmungs- oder Messelement mit einem Schaltelement in Verbindung steht, welches in einem ersten Schaltzustand die Versorgung des Verbrauchers aus dem Gleichstromnetz veranlassen kann und in einem zweiten Schaltzustand die Versorgung des Verbrauchers aus dem Wechselstromnetz veranlassen kann, wobei das Schaltelement ausgebildet ist, den zweiten Schaltzustand einzunehmen, wenn die Verfügbarkeit von Gleichspannung aus der Gleichstromquelle und/oder dem Energiespeicher unter ein vorgegebenes Niveau fällt (insbesondere unter eine vorgegebene Spannung im Gleichstromnetz). Der Verbraucher ist dabei insbesondere ein Heizelement. Die Erfindung betrifft auch ein Verfahren zur Durchführung dieser Betriebsweise.A particularly preferred embodiment of the invention provides

• - That the plastics processing machine has at least one consumer that can be operated with alternating current, and
• - that the direct current source and/or the energy store is connected to a determination or measuring element with which the availability of direct current from the direct current source and/or the energy store can be measured,

wherein the determining or measuring element is connected to a switching element which, in a first switching state, can cause the load to be supplied from the direct current network and, in a second switching state, can cause the load to be supplied from the alternating current network, the switching element being designed to provide the second To take switching state when the availability of DC voltage from the DC source and / or the energy storage falls below a predetermined level (in particular below a predetermined voltage in the DC network). The consumer is in particular a heating element. The invention also relates to a method for carrying out this mode of operation.

It should be noted with regard to the determination or measuring element that it can preferably be designed as a classic measuring element, but also, for example, as a digital logic circuit or as a manual switch/button. The design of the element also depends on the installation location of the system (e.g. in a production hall) and the infrastructure available there. The switching can be done by a digital signal, but also in other ways.

The plastics processing machine is preferably an injection molding machine; the heating element in this case is preferably the cylinder heater tion of a plasticizing unit of the injection molding machine.

Furthermore, preferably at least one storage element for electrical energy, in particular a capacitor, is electrically connected to the DC intermediate circuit.

A further development provides that a control circuit is electrically connected to the DC link via a switched-mode power supply, with the electrical consumers of the plastics processing machine being able to be supplied with energy from the DC link and controlled by the control circuit. The electrical consumer is, for example, a machine controller (CPU), a control unit (MMI), a control part of a servo converter, a sensor, an indicator lamp, a contactor, a switch, a valve, a magnet or a fan.

Regarding the further possible embodiment of the invention, reference is expressly made to the one already mentioned above EP 2 276 165 B1 referenced.

The invention thus allows effective use of the potential of direct current technology (DC technology) and provides an industrial direct current network for the power supply, which is fed with regenerative energy. A plastics processing machine, in particular an injection molding machine, with variable-speed drives and all consumers can be directly connected to a direct current network (such as in particular the cylinder heating of a plasticizing unit), including the control voltage generation.

The DC intermediate circuit of the plastics processing machine is connected loss-free to the DC network by a connection module, preferably including a charging circuit and an EMC filter. This also enables the loss-free feeding of recuperative braking energy from the manufacturing process, in particular from the injection molding process, into the DC network.

Consumers that are not recuperative, such as the cylinder heating of the plasticizing unit in particular, can be fed directly from the DC intermediate circuit by means of semiconductor switching elements, for example IGBTs.

• 1 schematisch das elektrische Schaltbild einer Fertigungsanlage umfassend eine Energieversorgung und eine Spritzgießmaschine gemäß einer ersten Ausführungsform der Erfindung und
• 2 das Schaltbild gemäß 1 nach einer zweiten Ausführungsform der Erfindung.

Exemplary embodiments of the invention are shown in the drawing. Show it:

• 1 schematically shows the electrical circuit diagram of a production plant comprising a power supply and an injection molding machine according to a first embodiment of the invention and
• 2 according to the circuit diagram 1 according to a second embodiment of the invention.

In 1 An electrical circuit diagram is shown, which shows a production plant 1 that includes an injection molding machine 2 that is supplied with electrical energy via a power supply 3 .

The energy supply 3 comprises two components: The first component is an AC network 4 (three phases L1, L2 and L3 are indicated), which feeds electrical energy into a DC network 6 via a converter 5 (rectifier). The second component is a direct current source 7 together with an (optional) energy store 8 which feeds electrical energy into the direct current network 6 . The direct current source 7 is designed here as a photovoltaic system that generates direct current from solar energy. The energy store 8 is a battery in which excess energy is stored and can be called up again when required.

The injection molding machine 2 can be electrically connected to a DC intermediate circuit 21 via a connection module 9 (this also includes a charging circuit, a bridging relay and an EMC filter). A main switch HS for switching on the machine is also indicated.

In the present case, the injection molding machine is designed as a purely electric injection molding machine. Accordingly, all drives of the machine are designed electrically, preferably with servo motors. Shown are three motors 17, 18 and 19, with which the required adjustment movements of the machine are accomplished. The motor 17 is used to drive the clamping unit of the injection molding machine. The motor 18 is used to drive the injection unit. The motor 19 is used here to drive another axis z. B. can be that of an ejector. The motors 17, 18, 19 are also suitable to be operated as a generator, i. H. to generate electrical energy from kinetic energy.

Also shown is a heating element 10, which here is the cylinder heater of a plasticizing unit. The heating element 10 is suitable for high voltages, in particular for voltages greater than or equal to 900 VDC. Furthermore, the heating element 10 is suitable for absorbing high power peaks that are only effective for a short time, in particular of at least 30 kW over a period of at least 250 ms.

The motors and the heating element are all electrically connected to the DC intermediate circuit 21 .

Energy can be exchanged via this DC intermediate circuit network if, e.g. B. a drive is delayed (braked), thereby working as a generator and feeds energy into the DC intermediate circuit 21, which can be removed from another consumer, z. B. to accelerate another axis of the machine by means of another consumer.

The DC intermediate circuit 21 is electrically connected to an electrical storage element 14 (energy store) in the form of a high-capacity capacitor. When braking, the capacitor 14 can be charged, which has advantages in the recuperative working mode.

A control circuit 15 required for the operation of the injection molding machine 2 is supplied with electrical energy from the DC intermediate circuit 21 via a switching power supply 16 for generating a control voltage (eg 24 VDC). The control circuit 15 supplies a variety of electrical consumers such. B. Machine controls (CPU; control or computing unit), an operating unit (MMI; screen, input unit), a control part of a servo converter (CPU), sensors, indicator lamps, contactors, switches, valves, magnets, etc.. These electrical consumers represent a certain proportion of the total energy consumption (e.g. 500 W).

A load, shown as an example for the load 10 in the exemplary embodiment in the form of the heating element, can be connected to the DC intermediate circuit 21 by means of a semiconductor switching element 11 . The semiconductor switching element 11 can be arranged within the machine control. In the exemplary embodiment, the semiconductor switching element is a bipolar transistor with an insulated gate electrode (insulated-gate bipolar transistor, IGBT for short). This is a semiconductor component that is used in power electronics because it combines the advantages of the bipolar transistor (good conduction behavior, high blocking voltage, robustness) and the advantages of a field effect transistor (almost powerless control). A certain robustness against short circuits is also advantageous since the IGBT limits the load current.

The heating element 10 is designed in such a way that it is suitable for the high or maximum permissible voltage of the DC intermediate circuit (e.g. 900 VDC), short-term (e.g. for 250 ms) high power peaks (e.g. 30 kW ) and can fulfill its actual purpose (here: the heating of a zone of the plasticizing cylinder) with regard to the rated output.

The semiconductor switching element 11 can be controlled as a function of the temperature T of the heating element 10 by a corresponding controller (in a closed control loop) in order to maintain a target temperature; For this purpose, a corresponding temperature sensor is then to be provided on the heating element 10 _, which detects the actual temperature T actual . For the exact procedure in this regard, reference is expressly made to the EP 2 276 165 B1 referenced.

In 1 the arrows indicate the direction in which energy is flowing. Accordingly, the direct current source 7 can only supply energy, while the energy store 8 can both supply and absorb energy. Excess energy, which was obtained in particular from recuperation or which results from the photovoltaic system in the event of a surplus, can also be released into the AC network 4 .

The AC network 4 typically has a voltage of 400 VAC. In the direct current network 6 and in the direct current intermediate circuit 21, for example, voltages of approximately 600 VDC are sought. The control circuit 15 is mostly operated with 24 VDC.

In 2 a further development of the proposed system is shown. The system shown there allows hybrid operation.

• Zur Stabilisierung des Gleichstromnetzes 6 erfolgt, wie oben dargelegt, dessen Ankopplung an das Wechselstromnetz 4; im Falle einer Unter- oder Überversorgung wird Energie über den Stromrichter 5 entweder vom Wechselstromnetz 4 in das Gleichstromnetz 6 eingespeist oder Energie aus dem Gleichstromnetz 6 über den Stromrichter (in diesem Falle fungierend als Wechselrichter) an das Wechselstromnetz 4 abgegeben.

The embodiment shown there represents an advantageous solution to the following problem:

• To stabilize the direct current network 6, as explained above, it is coupled to the alternating current network 4; In the event of undersupply or oversupply, energy is fed via the converter 5 either from the AC grid 4 into the DC grid 6 or energy is released from the DC grid 6 via the converter (acting as an inverter in this case) to the AC grid 4.

If sufficient direct current energy (particularly from photovoltaics) is available, additional excess energy can be fed into the alternating current network 4 in addition to supplying the consumers 10, 17, 18, 19 and feeding it into the energy store 8.

In the opposite case, ie when there is a lack of direct current energy, energy from the alternating current network 4 supports the voltage in the direct current network 6. In this case, however, there are undesirable transformation losses as a result of the rectification.

It is therefore expedient to feed consumers (in particular the heating element 10) that do not necessarily require a direct current supply directly from the alternating current network 4.

For this, according to the solution 2 a determination or measuring element 12 is provided, which detects the energy status of the direct current source 7 or of the energy store 8 and determines whether sufficient energy is available to maintain the required voltage in the direct current network 6 .

If this is the case, the consumers are supplied directly with direct current from the direct current network 6.

However, if this is not the case (and consequently the voltage of the direct current source 7 or of the energy storage device 8 falls below a predetermined limit value), a switching element 13, which is connected to the determination or measuring element 12, causes a switchover in such a way that the consumer ( So here the heating element 10) is coupled directly to the AC mains 4 and is supplied with energy by this. The switching element 13 comprises an AC semiconductor switching element 20 or it interacts with one, with the semiconductor switching element 20 preferably being embodied as a TRIAC (Triode for Alternating Current).

By means of the determining or measuring element 12 (detector unit), an approaching or acute shortage of direct current is thus detected in the direct current network and a switching signal is generated. The controller of the injection molding machine reacts to this and switches (via the switching element 13) individual or all zones of the cylinder heating from DC to AC supply.

This can generally be provided for all consumers that do not necessarily require a DC supply.

1. a) Messen der Verfügbarkeit von Gleichspannung aus der Gleichstromquelle 7 und/oder dem Energiespeicher 8, insbesondere der elektrischen Spannung im Gleichstromnetz 6;
2. b) Speisung aller elektrischen Verbraucher aus dem Gleichstromnetz 6, falls die Verfügbarkeit von Gleichspannung oberhalb eines vorgegebenen Niveaus liegt, insbesondere oberhalb einer vorgegebenen elektrischen Spannung im Gleichstromnetz 6 (erster Schaltzustand des Schaltelements 13);
3. c) Falls die Verfügbarkeit von Gleichspannung unter das vorgegebene Niveau, insbesondere unterhalb die vorgegebene elektrische Spannung, im Gleichstromnetz 6 fällt: Umschalten der Stromversorgung für mindestens einen Verbraucher, der für den Betrieb mit Wechselstrom geeignet ist, so dass dieser direkt aus dem Wechselstromnetz 4 versorgt wird (zweiter Schaltzustand des Schaltelements 13).

The corresponding procedure is therefore:

1. a) measuring the availability of direct voltage from the direct current source 7 and/or the energy store 8, in particular the electrical voltage in the direct current network 6;
2. b) feeding all electrical loads from the DC network 6 if the availability of DC voltage is above a predetermined level, in particular above a predetermined electrical voltage in the DC network 6 (first switching state of the switching element 13);
3. c) If the availability of direct voltage falls below the specified level, in particular below the specified electrical voltage, in the direct current network 6: switchover of the power supply for at least one consumer that is suitable for operation with alternating current so that it is supplied directly from the alternating current network 4 is (second switching state of the switching element 13).

As an aside, it should be mentioned that several plastics processing machines, in particular injection molding machines, can of course also be connected to the direct current network. It is also possible to connect other consumers here.

Reference List

1

manufacturing plant

2

Plastic processing machine (injection molding machine)

3

power supply

4

Alternating current grid (AC grid)

5

power converter

6

direct current network (DC network)

7

Direct current source (photovoltaic system)

8th

energy storage (battery)

9

connection module

10

heating element

11

Semiconductor switching element (IGBT)

12

determining or measuring element

13

switching element

14

storage element (capacitor)

15

control circuit

16

switching power supply

17

engine

18

engine

19

engine

20

AC semiconductor switching element (TRIAC)

21

DC intermediate circuit

QUOTES INCLUDED IN DESCRIPTION

This list of the documents cited by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent Literature Cited

• EP 2276165 B1 [0002, 0015, 0031]

Claims (12)

Manufacturing plant (1) comprising at least one plastics processing machine (2) and an energy supply (3), characterized in that the energy supply (3) comprises: - an AC network (4) which is connected to a DC network (6) via a converter (5). and - a direct current source (7) which is connected to the direct current network (6), the plastics processing machine (2) being able to be connected to the direct current network (6) in order to be supplied with electrical energy from it. manufacturing plant claim 1 , characterized in that the direct current source (7) is a photovoltaic system. manufacturing plant claim 1 or 2 , characterized in that the direct current network (6) can be connected to an energy store (8). Production plant according to one of Claims 1 until 3 , characterized in that the plastics processing machine (2) has at least one variable-speed drive (17, 18, 19). Production plant according to one of Claims 1 until 4 , characterized in that the plastics processing machine (2) has a direct current intermediate circuit (21) which can be electrically connected to the direct current network (6) via a connection module (9). manufacturing plant claim 5 , characterized in that the plastics processing machine (2) has at least one heating element (10), this being heated from the DC intermediate circuit (21) via a semiconductor switching element (11), in particular by a bipolar transistor with an insulated gate electrode (Insulated Gate Bipolar Transistor, IGBT) , can be supplied with energy. Production plant according to one of Claims 1 until 6 , characterized in that - that the plastics processing machine (2) has at least one consumer that can be operated with alternating current, and - that the direct current source (7) and/or the energy store (8) is connected to a determination or measuring element (12). , with which the availability of direct voltage from the direct current source (7) and/or the energy store (8) can be measured, the determining or measuring element (12) being connected to a switching element (13) which, in a first switching state, can cause the load to be supplied from the DC network (6) and can cause the load to be supplied from the AC network (4) in a second switching state, the switching element (13) being designed to assume the second switching state when the availability of DC voltage from the Direct current source (7) and/or the energy store (8) below a predetermined level, in particular below a predetermined spa nection in the DC network (6), falls. manufacturing plant claim 7 , characterized in that the consumer is a heating element. Production plant according to one of Claims 1 until 8th , characterized in that the plastics processing machine (2) is an injection molding machine. manufacturing plant claim 8 and 9 , characterized in that the heating element is the cylinder heater of a plasticizing unit of the injection molding machine. Production plant according to one of Claims 1 until 10 , characterized in that at least one storage element (14) for electrical energy, in particular a capacitor, is electrically connected to the DC intermediate circuit (21). Production plant according to one of Claims 1 until 11 , characterized in that a control circuit (15) is electrically connected to the DC intermediate circuit (21) via a switched-mode power supply (16), it being possible for the electrical consumers of the plastics processing machine (2) to be supplied with energy from the DC intermediate circuit (21) and from the control circuit (15) can be controlled from.

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