Injection molding machine energy-saving system powered by servo drive bus voltage

Abstract

The invention relates to the technical field of electric control equipment for injection molding production, in particular to an injection molding machine energy-saving system powered by servo drive bus voltage, which comprises a power supply module, a drive module, a heating module, a detection module and a control module, the control module is a PLC upper computer and is used for receiving a voltage signal of the bus voltage sensor and energy consumption data of the intelligent electric meter, calculating the power of the screw heating gap in real time and sending a control instruction to the servo power supply module and the DC-AC module to achieve dynamic optimization of system energy. The regenerative electric energy is accurately output to the screw for heating according to the heating notch power delta P, the originally wasted electric energy is reutilized and directly converted into heat energy needed for heating the screw, the energy utilization rate is remarkably increased, and energy saving is achieved.

Description

Technical Field

[0001] This invention relates to the field of electrical control equipment technology in injection molding production, and in particular to an energy-saving system for injection molding machines powered by servo-driven bus voltage. Background Technology

[0002] The operation of an injection molding machine typically involves multiple actions, including injection, holding pressure, plasticizing, retraction, mold opening, ejection, and mold closing. Different actions have different power requirements. During the injection stage, due to the need for high pressure and speed, the bus voltage increases, and the driver outputs more power to the motor. Conversely, during the mold opening and closing stages, the power required is lower, and the bus voltage decreases. Furthermore, when the injection molding machine performs deceleration or braking, the servo motor, due to inertia, enters a generator state, converting mechanical energy into electrical energy. The resulting regenerative energy is fed back to the bus.

[0003] Currently, injection molding machines generally use braking resistors to convert the regenerated electrical energy into heat energy loss. This not only wastes electrical energy but also increases the risk of overheating inside the electrical cabinet.

[0004] Meanwhile, during the operation of the injection molding machine, the servo drive system and the screw heating system are powered separately. Without the installation of current transformers, it is impossible to accurately monitor the specific energy consumption of each part, and it is also difficult to analyze the feasibility of energy optimization. Therefore, we propose an energy-saving system for injection molding machines powered by servo drive bus voltage to solve the above problems. Summary of the Invention

[0005] This invention addresses the deficiency in existing injection molding machine technologies where regenerated electrical energy cannot be reused by providing an energy-saving system for injection molding machines powered by servo drive bus voltage.

[0006] This invention is achieved through the following technical solution: A servo-driven bus voltage-powered energy-saving system for injection molding machines includes: The power supply module includes a mains power supply circuit and a servo power supply module connected to the mains power supply circuit. The servo power supply module is connected to the bus to provide a stable DC voltage to the bus, and the servo power supply module is connected to a braking resistor to discharge redundant power of the bus. The drive module includes several servo drives. Each servo drive is connected to a bus at one end and to a corresponding servo motor at the other end. The servo drive is used to drive the servo motor to run and to receive regenerative energy fed back by the servo motor when the servo motor brakes or decelerates. The heating module includes a DC-AC module, one end of which is connected to the busbar and the other end is connected to the screw thermocouple. The DC-AC module is used to invert the DC power of the busbar into AC power to supply power to the screw thermocouple so as to realize screw heating. The detection module includes a bus voltage sensor and a smart meter. The bus voltage sensor is installed on the bus to monitor the bus voltage and feed it back to the PLC host computer. The smart meter is used to integrate multiple current data, calculate the energy consumption of each link in the system, and communicate bidirectionally with the PLC host computer. The control module, which is a PLC host computer, is used to receive voltage signals from the bus voltage sensor and energy consumption data from the smart meter, calculate the power of the screw heating gap in real time, and send control commands to the servo power supply module and the DC-AC module to realize dynamic energy optimization of the system.

[0007] In a preferred embodiment of the present invention, the voltage overvoltage threshold range of the bus is set, and the threshold range is V. max -20V to V max V max This is the upper limit of the bus voltage overvoltage. Setting this threshold band helps maintain the current operation and avoids frequent switching.

[0008] In a preferred embodiment of the present invention, the servo power module receives instructions from the PLC host computer to adjust the bus power supply and control the switching of the braking resistor in order to cope with changes in bus voltage and the need for redundant power discharge.

[0009] In a preferred embodiment of the present invention, the DC-AC module adjusts the inverter output power according to the PLC host computer instruction to match the screw heating requirements, and prioritizes the use of bus regenerated power to power the screw thermocouple, thereby achieving efficient recycling and utilization of regenerated energy and improving the energy-saving level and energy utilization efficiency of the injection molding machine system.

[0010] In a preferred embodiment of the present invention, the detection module further includes a first current transformer for monitoring the total input current of the power grid circuit, a second current transformer for monitoring the current of the servo power module, and a third current transformer for monitoring the heating current of the screw thermocouple, thereby constructing a multi-layer monitoring network to detect and summarize various data.

[0011] In a preferred embodiment of the present invention, the smart meter integrates data from the first current transformer, the second current transformer, and the third current transformer to respectively count the energy consumption of the grid power supply circuit input, the servo power module, and the screw thermocouple heating link, thereby achieving comprehensive perception of multi-dimensional current information such as grid input, bus power supply, and screw heating, and constructing the underlying data support for system-level energy consumption monitoring and control.

[0012] In a preferred embodiment of the present invention, the formula for calculating the power of the screw heating notch is as follows: P= - The regenerated electrical energy is output with a ΔP limit via a PLC host computer to prevent temperature overshoot. For the heating power required by the screw process, It can supplement the power grid.

[0013] In a preferred embodiment of the present invention, the servo drive has a built-in power quality optimization module to perform harmonic suppression and voltage compensation on the regenerated power feedback, ensuring that the bus voltage fluctuation is controlled within a safe threshold, and providing high-quality energy input for subsequent regenerated power to be used for screw heating and redundant power management.

[0014] The beneficial effects of this invention are: 1. This invention precisely outputs regenerated electrical energy to the screw heating according to the heating gap power ΔP, making secondary use of the originally wasted electrical energy and directly converting it into the heat energy required for screw heating, significantly improving energy utilization and achieving energy saving; 2. This invention, through the cooperation of smart meters and multiple current transformers, accurately counts the current data of each link, calculates the heating power gap based on the data monitored by the energy meter, and, together with the smart meters in the system, can accurately grasp the energy consumption of screw heating and the utilization of regenerated electricity, providing data support for energy consumption analysis and optimization. Attached Figure Description

[0015] Figure 1 This is a structural block diagram of an energy-saving injection molding machine system powered by servo drive bus voltage according to the present invention; Figure 2 This invention relates to the regenerative power scheduling logic of an injection molding machine energy-saving system powered by servo-driven bus voltage. Detailed Implementation

[0016] The preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings, so that the advantages and features of the present invention can be more readily understood by those skilled in the art.

[0017] like Figure 1-2 The energy-saving system for an injection molding machine powered by servo drive bus voltage, as shown, includes: The power supply module consists of a mains power supply circuit and a servo power supply module connected to the mains power supply circuit. The servo power supply module is connected to the bus to provide a stable DC voltage to the bus. The overvoltage threshold range of the bus is set, and its threshold range is V. max -20V to V max V max This is the upper limit of the bus voltage overvoltage. Setting this threshold band helps to maintain the current operation and avoid frequent switching. The busbar is also connected to a DC-AC module. One end of the DC-AC module is connected to the busbar, and the other end is connected to the screw thermocouple. The DC-AC module is used to invert the DC power of the busbar into AC power to power the screw thermocouple so as to achieve screw heating. The servo power module is connected to a braking resistor to discharge redundant power from the bus. The servo power module receives instructions from the PLC host computer to adjust the power supply to the bus and control the switching of the braking resistor to cope with changes in bus voltage and the need to discharge redundant power. The PLC host computer acts as the control module, receiving voltage signals from the bus voltage sensor and energy consumption data from the smart meter. It then calculates the screw heating gap power in real time and sends control commands to the servo power module and the DC-AC module to achieve dynamic energy optimization of the system. The formula for calculating the screw heating gap power is as follows: P= - The regenerated electrical energy is output with a ΔP limit via a PLC host computer to prevent temperature overshoot. For the heating power required by the screw process, It can supplement the power grid; the DC-AC module adjusts the inverter output power according to the PLC host computer instructions to match the screw heating demand, and prioritizes the use of bus regenerated power to power the screw thermocouple, so as to realize the efficient recycling and utilization of renewable energy and improve the energy-saving level and energy utilization efficiency of the injection molding machine system. When the system is running, such as during injection deceleration or mold opening braking in an injection molding machine, the regenerative electrical energy generated by the servo motor braking will be fed back into the bus. If the DC-AC module and screw thermocouple cannot completely absorb this energy, the bus voltage will rise rapidly. At this time, the PLC host computer sends control commands to the servo power module based on the real-time data from the bus voltage sensor. It also includes several servo drives, each employing a dual-function architecture: one end is stably connected to the bus via a highly compatible interface, responding in real-time to the bus's power scheduling commands; the other end connects precisely to the corresponding servo motor via a customized power cable, constructing a drive-feedback closed loop. When the injection molding machine performs routine actions such as injection, mold opening, and mold closing, the servo drive acts as the power output hub, precisely adjusting the output power and speed curves according to the motion control commands from the PLC host computer, driving the servo motor to operate along the process trajectory, and efficiently converting the bus's electrical energy into the motor's mechanical energy.

[0018] When the injection molding machine enters braking or deceleration mode, such as the screw retraction braking after injection or the mechanism deceleration after mold opening, the servo motor switches from electric mode to generator mode due to inertial load. At this time, the servo drive automatically activates the regenerative energy recovery function: the internal energy feedback circuit responds quickly, converting the AC power generated by the servo motor rotating and cutting magnetic lines into DC power compatible with the bus, and stably feeding it back to the bus, forming an energy closed loop from mechanical energy to electrical energy to bus energy storage. At the same time, the servo drive has a built-in power quality optimization module to suppress harmonics and compensate voltage for the regenerative energy feedback, ensuring that the bus voltage fluctuation is controlled within a safe threshold, providing high-quality energy input for subsequent regenerative energy use for screw heating and redundant power management. The system also incorporates a multi-layered monitoring network to detect and aggregate various data, primarily including bus voltage sensors and smart meters. The bus voltage sensors are installed on the bus to monitor the bus voltage and feed it back to the PLC host computer. The smart meters integrate multiple energy data streams, execute load balancing strategies, calculate energy consumption at each stage of the system, and communicate bidirectionally with the PLC host computer. The smart meters not only transmit energy consumption data and load balancing strategy execution results to the PLC but also receive control commands from the PLC, achieving closed-loop control of data acquisition, strategy calculation, command execution, and effect feedback. This upgrades the system's energy management from passive monitoring to proactive optimization. It also includes a first current transformer for monitoring the total input current of the power grid circuit, a second current transformer for monitoring the current of the servo power module, and a third current transformer for monitoring the heating current of the screw thermocouple. The smart meter integrates the data from the first, second, and third current transformers to statistically analyze the energy consumption of the power grid circuit input, the servo power module, and the screw thermocouple heating process. This enables comprehensive perception of multi-dimensional current information such as power grid input, bus power supply, and screw heating, and builds the underlying data support for system-level energy consumption monitoring and control.

[0019] Power dispatch logic as follows Figure 2 As shown, the system first checks if the real-time bus voltage exceeds the bus overvoltage threshold. If it does, it further checks if the screw compressor needs heating. If heating is required, the DC-AC converter module is activated to convert regenerated electrical energy into screw compressor heat energy. If heating is not required, a braking resistor is activated to dissipate redundant electrical energy to prevent bus overvoltage. Regenerated electrical energy prioritizes heating, and redundant energy is transferred to the braking resistor. When the bus voltage does not exceed the threshold, the power grid directly supplies power to the screw compressor for heating.

[0020] In this embodiment, a DC-AC inverter module and an energy detection module are installed in the injection molding machine cabinet. When the servo motor brakes, it allocates regenerated energy according to the energy scheduling logic. During the injection deceleration, the screw is in the foremost position. At this time, the injection molding machine nozzle is exposed to a low temperature environment and needs thermocouple heating to maintain the temperature and prevent the new material from condensing. At this time, the injection deceleration generates regenerated electrical energy. The regenerated electrical energy is fed back to the DC bus through the driver inverter unit, and then supplied to the nozzle thermocouple through the DC-AC module and converted into heat energy for consumption. Secondly, during mold opening and braking, the screw begins to rotate and pre-plasticize the raw material for the next cycle. At this time, the thermocouple in the molten section of the screw needs thermal energy to maintain its normal operating temperature. Mold opening and braking at this time generate regenerative electrical energy, which is fed back to the DC bus through the driver inverter unit, and then supplied to the thermocouple in the molten section of the screw through the DC-AC module, where it is converted into thermal energy for consumption.

[0021] It should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," "setting," and "equipped with" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0022] The embodiments described above are merely examples of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention.

Claims

1. A servo-driven bus voltage-powered energy-saving system for injection molding machines, characterized in that, include: The power supply module includes a mains power supply circuit and a servo power supply module connected to the mains power supply circuit. The servo power supply module is connected to the bus to provide a stable DC voltage to the bus. The drive module includes several servo drives. Each servo drive is connected to a bus at one end and to a corresponding servo motor at the other end. The servo drive is used to drive the servo motor to run and to receive regenerative energy fed back by the servo motor when the servo motor brakes or decelerates. A heating module is used to invert the regenerative electrical energy in the servo bus from DC to AC and supply it to the screw for heating; The detection module includes a bus voltage sensor and a smart meter. The detection module is used to monitor the servo bus voltage, screw temperature and machine energy consumption in real time. The control module, which is a PLC host computer, is used to receive voltage signals from the bus voltage sensor and energy consumption data from the smart meter, calculate the power of the screw heating gap in real time, and send control commands to the servo power supply module and the DC-AC module to realize dynamic energy optimization of the system.

2. The energy-saving system for injection molding machines powered by servo-driven bus voltage according to claim 1, characterized in that: The voltage overvoltage threshold range of the bus is set, and its threshold range is V. max -20V to V max .

3. The energy-saving system for injection molding machines powered by servo drive bus voltage according to claim 2, characterized in that: The servo power module is connected to a braking resistor, which is used to discharge redundant power from the bus.

4. The energy-saving system for injection molding machines powered by servo drive bus voltage according to claim 3, characterized in that: The servo power module receives instructions from the PLC host computer to adjust the bus power supply and control the switching of the braking resistor in order to cope with changes in bus voltage and the need for redundant power discharge.

5. The energy-saving system for injection molding machines powered by servo drive bus voltage according to claim 1, characterized in that: The heating module includes a DC-AC module and a screw thermocouple. One end of the DC-AC module is connected to the busbar, and the other end is connected to the screw thermocouple. The DC-AC module is used to invert the DC power from the busbar into AC power to supply power to the screw thermocouple for screw heating.

6. The energy-saving system for injection molding machines powered by servo drive bus voltage according to claim 5, characterized in that: The DC-AC module adjusts the inverter output power according to the PLC host computer instructions to match the screw heating requirements and prioritizes the use of bus regenerated power to power the screw thermocouple.

7. The energy-saving system for injection molding machines powered by servo drive bus voltage according to claim 1, characterized in that: The bus voltage sensor is installed on the bus to monitor the bus voltage and feed it back to the PLC host computer; the smart meter is used to integrate multiple current data, count the energy consumption of each link in the system, and communicate bidirectionally with the PLC host computer.

8. The energy-saving system for injection molding machines powered by servo drive bus voltage according to claim 7, characterized in that: The detection module also includes a first current transformer for monitoring the total input current of the power grid circuit, a second current transformer for monitoring the current of the servo power module, and a third current transformer for monitoring the heating current of the screw thermocouple.

9. The energy-saving system for injection molding machines powered by servo drive bus voltage according to claim 8, characterized in that: The smart meter integrates data from the first current transformer, the second current transformer, and the third current transformer to statistically analyze the energy consumption of the grid power supply circuit input, the servo power module, and the screw thermocouple heating circuit.

10. The energy-saving system for injection molding machines powered by servo drive bus voltage according to claim 1, characterized in that: The formula for calculating the power of the screw heating notch is as follows: P= - The regenerated electrical energy is output at a limit of ΔP via the PLC host computer to avoid temperature overshoot.

11. The energy-saving system for injection molding machines powered by servo drive bus voltage according to claim 1, characterized in that: The servo drive has a built-in power quality optimization module that performs harmonic suppression and voltage compensation on the regenerated power feedback.

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