Method for pressure relief of injection molding machine from pump oil line by servo system feedback torque

Abstract

The application discloses a method for realizing pressure relief of an injection molding machine from a pump oil line through servo system feedback torque, which sets pressure relief rotating speed S pr and pressure relief torque T min on an injection molding machine control system, and enables the injection molding machine control system to communicate with each servo system corresponding to each slave pump to obtain real-time torque of each servo system corresponding to each slave pump; when the injection molding machine switches from multi-pump combined flow operation to single-pump operation, at this time, the injection molding machine control system controls each slave pump to rotate reversely at pressure relief rotating speed S pr and compares torque of each servo system corresponding to each slave pump with pressure relief torque T min in real time; when torque of a certain servo system corresponding to a certain slave pump is less than pressure relief torque T min , it is judged that pressure relief of the slave pump is completed, and the slave pump is controlled to stop rotating through the servo system corresponding to the slave pump; the method has the advantage that pressure relief can be realized without additionally setting pressure sensors on each oil line corresponding to each slave pump, thereby greatly reducing cost.

Description

Technical Field

[0001] This invention relates to a method for relieving pressure from the pump oil circuit of an injection molding machine, and more particularly to a method for relieving pressure from the pump oil circuit of an injection molding machine by means of torque feedback from a servo system. Background Technology

[0002] Injection molding machines play a crucial role in modern manufacturing. Their hydraulic systems typically contain N pumps, where N is an integer greater than or equal to 2. One pump is the master pump, and the other N-1 pumps are slave pumps. The master pump's hydraulic circuit is equipped with a pressure sensor. This hydraulic system usually operates in two modes: multi-pump confluence and single-pump operation. In multi-pump confluence mode, all slave pumps follow the master pump. In single-pump operation, the master pump rotates independently, and all other slave pumps remain stationary. Regardless of whether the master pump is operating in multi-pump confluence or single-pump mode, the injection molding machine control system continuously monitors the pressure values ​​detected by the pressure sensors on the master pump's hydraulic circuit. Based on these pressure values, the system adjusts the speed of the servo system driving the master pump in real time to ensure the master pump operates at the set parameters.

[0003] The design of multi-pump confluence operation is crucial for the efficient production of injection molding machines, but not all injection molding processes require it. After multi-pump confluence operation, there may be a need to switch to single-pump operation to meet the working requirements of different injection molding processes. However, when switching from multi-pump confluence operation to single-pump operation, a significant challenge typically arises: the pressure in the hydraulic circuit corresponding to the pump becomes relatively high, forming a high-pressure hydraulic circuit. This causes the servo system driving the pump corresponding to this high-pressure hydraulic circuit to generate a considerably high current when stationary, leading to overload problems. This overload problem can result in servo system overheating, increased energy consumption, and related adverse effects. Therefore, the servo system overload problem caused by switching from multi-pump confluence operation to single-pump operation not only reduces the efficiency of the injection molding machine but may also increase maintenance costs, causing unnecessary disruption to industrial production. Therefore, it is necessary to address the high-pressure hydraulic circuit problem that occurs when switching from multi-pump confluence operation to single-pump operation to improve the working efficiency of the injection molding machine, reduce servo system energy consumption, and extend the lifespan of the servo system.

[0004] A relatively mature solution to the high-pressure oil circuit problem when switching from multi-pump confluence operation to single-pump operation in injection molding machines is to install pressure sensors at the outlet of all slave pumps. When switching from multi-pump confluence operation to single-pump operation, the main pump executes the actions according to the preset single-pump action requirements. Instead of directly stopping each slave pump through its corresponding servo system, the hydraulic system collects the pressure values ​​detected by the pressure sensors on each slave pump's oil circuit in real time. Based on these pressure values, it generates corresponding pressure relief control commands, controlling the servo system of each slave pump to drive each pump to perform a pressure relief action. This maintains a low-pressure state for each slave pump when it stops, reducing the energy consumption and failure rate of the servo system corresponding to each slave pump. However, this slave pump oil circuit pressure relief solution requires an additional pressure sensor at each slave pump's oil circuit, increasing costs. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a low-cost method for releasing pressure from the pump oil circuit of an injection molding machine by means of feedback torque from a servo system.

[0006] The technical solution adopted by this invention to solve the above-mentioned technical problems is as follows: a method for realizing pressure relief of the oil circuit of the pump in an injection molding machine through feedback torque of a servo system. The injection molding machine has N pumps, where N is an integer greater than or equal to 2, of which one pump is the master pump and the other N-1 pumps are slave pumps. A pressure sensor is installed on the oil circuit corresponding to the master pump. When the injection molding machine performs a multi-pump confluence operation, all slave pumps follow the master pump. When the injection molding machine performs a single-pump operation, only the master pump needs to rotate independently, and all other slave pumps need to stop rotating. The method includes the following steps:

[0007] Step 1: Set the pressure relief parameters in the injection molding machine control system: pressure relief speed S pr and pressure relief torque T min Among them, the depressurization speed S pr and pressure relief torque T min Based on pre-testing of the actual pressure relief requirements of the pump;

[0008] Step 2: When the injection molding machine switches from multi-pump confluence operation to single-pump operation, the injection molding machine control system, on the one hand, controls the main pump to operate independently and execute the preset single-pump operation through the servo system corresponding to the main pump; on the other hand, it controls each slave pump to operate at a depressurization speed S through the servo system corresponding to each slave pump. pr Reverse rotation, and at each pump depressurization speed S pr During the reverse rotation, the torque of each slave pump's corresponding servo system is acquired in real time. When the acquired torque of a slave pump's corresponding servo system is less than the pressure relief torque T, minAt this time, the injection molding machine control system controls the slave pump to stop rotating through the corresponding servo system until all N-1 slave pumps stop rotating, at which point the pressure relief of all slave pumps is completed.

[0009] The injection molding machine control system and the servo system corresponding to each slave pump communicate using EtherCat communication technology. The injection molding machine control system can obtain the torque from the servo system corresponding to each slave pump through EtherCat communication technology.

[0010] Relief speed S pr The pressure relief torque is 200 rpm. min It is 10%.

[0011] Compared with the prior art, the advantage of the present invention is that by setting the pressure relief speed S at the injection molding machine control system... pr and pressure relief torque T min This enables the injection molding machine control system to communicate with the servo system corresponding to each slave pump to obtain the real-time torque of each slave pump's servo system. When the injection molding machine switches from multi-pump confluence operation to single-pump operation, the injection molding machine control system controls each slave pump to operate at a depressurization speed S through the servo system corresponding to each slave pump. pr Reverse rotation, and real-time acquisition of torque and pressure relief torque T fed back from the corresponding servo system of each pump. min A comparison is made when the torque fed back from the servo system corresponding to the pump is less than the pressure relief torque T. min When the pump is depressurized, the corresponding servo system controls the pump to stop rotating. Thus, the method of the present invention achieves depressurization of the pump oil circuit of the injection molding machine through the torque fed back by the servo system, eliminating the need to install pressure sensors at each pump oil circuit, which greatly reduces costs. Attached Figure Description

[0012] Figure 1 The flowchart of the method for depressurizing the oil circuit of the injection molding machine by means of feedback torque from the servo system is shown in the present invention. Detailed Implementation

[0013] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0014] Example 1: As Figure 1 As shown, a method for depressurizing the oil circuit of a pump in an injection molding machine by feedback torque through a servo system is described. The injection molding machine has N pumps, where N is an integer greater than or equal to 2. One pump is the master pump, and the other N-1 pumps are slave pumps. A pressure sensor is installed on the oil circuit corresponding to the master pump. When the injection molding machine performs a multi-pump confluence operation, all slave pumps follow the master pump. However, when the injection molding machine performs a single-pump operation, only the master pump needs to rotate independently, and all other slave pumps need to stop rotating. The method includes the following steps:

[0015] Step 1: Set the pressure relief parameters in the injection molding machine control system: pressure relief speed S pr and pressure relief torque T min Among them, the depressurization speed S pr The pressure relief torque is 200 rpm. min It is 10%.

[0016] Step 2: When the injection molding machine switches from multi-pump confluence operation to single-pump operation, the injection molding machine control system controls the main pump to operate independently and execute the preset single-pump operation through the main pump's corresponding servo system. Simultaneously, it controls each slave pump to operate at a depressurization speed S through the slave pump's corresponding servo system. pr Reverse rotation, and at each pump depressurization speed S pr During the reverse rotation, the torque of each slave pump's corresponding servo system is acquired in real time. When the acquired torque of a slave pump's corresponding servo system is less than the pressure relief torque T, min At this time, the injection molding machine control system controls the slave pump to stop rotating through the corresponding servo system until all N-1 slave pumps stop rotating, at which point the pressure relief of all slave pumps is completed.

[0017] In this embodiment, the pressure relief speed S is set in the injection molding machine control system. pr and pressure relief torque T min Subsequently, when the injection molding machine switches from multi-pump confluence operation to single-pump operation, the injection molding machine control system controls each slave pump to operate at a depressurization speed S through the corresponding servo system of each slave pump. pr Reverse rotation, and real-time acquisition of the torque and pressure relief torque T of each servo system corresponding to the pump. min A comparison is made when the torque of a certain servo system corresponding to the pump is less than the pressure relief torque T. min When the pump is depressurized, the corresponding servo system controls the pump to stop rotating. Therefore, the method in this embodiment achieves depressurization of the injection molding machine's pump oil circuit through torque feedback from the servo system, eliminating the need for additional pressure sensors at each pump's corresponding oil circuit, thus significantly reducing costs.

[0018] Example 2: This example is basically the same as Example 1, except that: in this example, the injection molding machine control system and the servo system corresponding to each slave pump communicate using EtherCat communication technology. The injection molding machine control system can obtain the torque from the servo system corresponding to each slave pump through EtherCat communication technology.

Claims

1. A method for depressurizing the oil circuit of a pump in an injection molding machine by means of torque feedback from a servo system, wherein the injection molding machine has N pumps, where N is an integer greater than or equal to 2, wherein one pump is a master pump and the other N-1 pumps are slave pumps, and a pressure sensor is installed on the oil circuit corresponding to the master pump; when the injection molding machine performs a multi-pump confluence operation, all slave pumps operate in tandem with the master pump; and when the injection molding machine performs a single-pump operation, only the master pump needs to rotate independently, and all other slave pumps need to stop rotating, characterized in that... The method, in which no pressure sensors are installed on any of the oil lines corresponding to the pump, includes the following steps: Step 1: Set the pressure relief parameters in the injection molding machine control system: pressure relief speed. and pressure relief torque Among them, the depressurization speed and pressure relief torque Based on pre-testing of the actual pressure relief requirements of the pump; Step 2: When the injection molding machine switches from multi-pump confluence operation to single-pump operation, the injection molding machine control system, on the one hand, controls the main pump to operate independently and execute the preset single-pump operation through the servo system corresponding to the main pump; on the other hand, it controls each slave pump to operate at a depressurization speed through the servo system corresponding to each slave pump. Reverse rotation, and at each pump at the depressurization speed. During the reverse rotation, the torque of each slave pump's corresponding servo system is acquired in real time. When the acquired torque of a slave pump's corresponding servo system is less than the pressure relief torque... At this time, the injection molding machine control system controls the slave pump to stop rotating through the corresponding servo system until all N-1 slave pumps stop rotating, at which point the pressure relief of all slave pumps is completed.

2. The method for releasing pressure from the pump oil circuit of an injection molding machine by feedback torque through a servo system according to claim 1, characterized in that... The injection molding machine control system and the corresponding servo system of each slave pump communicate using EtherCat communication technology. The injection molding machine control system can obtain the torque from the corresponding servo system of each slave pump through EtherCat communication technology.

3. The method for releasing pressure from the pump oil circuit of an injection molding machine by feedback torque through a servo system according to claim 1, characterized in that... pressure relief speed The pressure relief torque is 200 rpm. It is 10%.

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