A servo control system for a powder molding machine die

Abstract

This invention relates to a servo control system for a powder molding machine die, comprising a hydraulic power source. The hydraulic power source's outlet and return lines are connected to the P1 and T1 ports of an electro-hydraulic servo valve, respectively. The A1 and B1 ports of the electro-hydraulic servo valve are connected to the lower and upper ports of a reset cylinder, respectively. The hydraulic power source's outlet and return lines are also connected to a pressure reducing valve and a first relief valve, respectively. The pressure reducing valve is connected to the inlet of a first check valve. The first check valve and the first relief valve are connected to the P2 and T2 ports of a solenoid directional valve, respectively. The A2 and B2 ports of the solenoid directional valve are connected to the upper and lower ports of the reset cylinder, respectively. A position sensor is mounted on the reset cylinder, and the position sensor is connected to a controller, which is in turn connected to the electro-hydraulic servo valve. This invention offers high control precision and effectively controls the upward filling and downward pressing movements of the die.

Description

Technical Field

[0001] This invention belongs to the field of powder metallurgy equipment technology, specifically relating to a servo control system for a powder forming machine die. Background Technology

[0002] In the powder compression molding process, the die movement mainly includes upward filling and downward pressing. During the upward filling process, the die movement needs precise control to ensure it matches the feeding process. During the downward pressing process, the die is subjected to pressing force and moves downward along with the pressing mechanism. When the pressing force is released, the die may move upward due to excessive pressure in the lower chamber of the reset cylinder. Furthermore, it is necessary to prevent the die and other mechanisms from moving downward on their own due to gravity; that is, to achieve the die holding function and prevent damage to the product inside the cavity due to sudden die movement.

[0003] Patent publication number CN112610549A discloses a servo-controlled filling system adapted to the feeding process and its working process. The solution uses a hydraulic servo control system with a servo proportional solenoid valve to control the position and speed of the die during the upward movement and filling process. The problems with this solution are: it cannot automatically compensate for die position errors caused by external interference, resulting in low control accuracy; and the control system cannot achieve die holding energy. Summary of the Invention

[0004] The purpose of this invention is to provide a servo control system for the die of a powder forming machine that provides precise control and effectively controls the upward and downward pressing motion of the die.

[0005] Therefore, the technical solution adopted by this invention is:

[0006] A servo control system for a powder molding machine die includes a hydraulic power source, an accumulator, an electro-hydraulic servo valve, a first relief valve, a pressure reducing valve, a first check valve, a solenoid directional valve, a reset cylinder, and a position sensor. The hydraulic power source's outlet and return lines are connected to the P1 and T1 ports of the electro-hydraulic servo valve, respectively. The A1 and B1 ports of the electro-hydraulic servo valve are connected to the lower and upper ports of the reset cylinder, respectively. The hydraulic power source's outlet and return lines are also connected to the pressure reducing valve and the first relief valve, respectively. The pressure reducing valve is connected to the first check valve... The valve inlet is connected, the first check valve and the first relief valve are connected to the P2 port and T2 port of the solenoid directional valve respectively, and the A2 port and B2 port of the solenoid directional valve are connected to the upper oil port and lower oil port of the reset cylinder respectively; an accumulator is provided between the hydraulic power source and the P1 port of the electro-hydraulic servo valve; a position sensor is provided on the reset cylinder to monitor the position of the reset cylinder piston and send it to the controller. The controller is used to control the displacement of the valve core in the electro-hydraulic servo valve, change the flow rate, and thus control the position and speed of the reset cylinder piston.

[0007] Compared with the prior art, the significant advantages of the present invention are:

[0008] (1) The present invention uses an electro-hydraulic servo valve to control the upward movement and filling process of the die, which has higher control accuracy and faster response speed compared with traditional pneumatic control or proportional valve control.

[0009] (2) The present invention uses a position sensor to monitor the position of the die and controls the die movement process through programming feedback, so that the die movement curve fits the preset curve better and automatically compensates for the position error in the die movement process, thereby further improving the control accuracy.

[0010] (3) The present invention can realize the die retaining function, prevent the die from sudden displacement caused by external force changes or its own gravity, thereby improving the product yield.

[0011] (4) During the downward pressing process, the present invention reduces the influence of hydraulic source pressure on the movement speed of the die by low-pressure oil replenishment, so that the die can better follow the movement of the pressing mechanism, which is conducive to improving the yield of thinner products. Attached Figure Description

[0012] Figure 1 This is the hydraulic circuit diagram for the die servo control of the present invention.

[0013] Figure 2 It is a filling control oil circuit diagram.

[0014] Figure 3 This is a pressure control oil circuit diagram.

[0015] 1 is the hydraulic power source, 2 is the accumulator, 3 is the electro-hydraulic servo valve, 4 is the first relief valve, 5 is the pressure reducing valve, 6 is the first check valve, 7 is the solenoid directional valve, 8 is the reset cylinder, and 9 is the position sensor. Detailed Implementation

[0016] The present invention will now be described in further detail with reference to the accompanying drawings.

[0017] Combination Figure 1The present invention discloses a servo control system for a powder molding machine die, comprising a hydraulic power source 1, an accumulator 2, an electro-hydraulic servo valve 3, a first overflow valve 4, a pressure reducing valve 5, a first check valve 6, a solenoid directional valve 7, a reset cylinder 8, and a position sensor 9. The oil outlet and return lines of the hydraulic power source 1 are respectively connected to the P1 and T1 ports of the electro-hydraulic servo valve 3, and the A1 and B1 ports of the electro-hydraulic servo valve 3 are respectively connected to the lower and upper oil ports of the reset cylinder 8. The oil outlet and return lines of the hydraulic power source 1 are further connected to the pressure reducing valve 4, a first relief valve 5, a first check valve 6, a solenoid directional valve 7, a reset cylinder 8, and a position sensor 9. Pressure reducing valve 5 is connected to the first relief valve 4. Pressure reducing valve 5 is connected to the oil inlet of the first check valve 6. The oil outlet of the first check valve 6 and the first relief valve 4 are respectively connected to the P2 port and T2 port of the solenoid directional valve 7. The A2 port and B2 port of the solenoid directional valve 7 are respectively connected to the upper oil port and lower oil port of the reset cylinder 8. An accumulator 2 is provided between the hydraulic power source 1 and the P1 port of the electro-hydraulic servo valve 3. A position sensor 9 is provided on the reset cylinder 8. The position sensor 9 is connected to the controller. The controller is connected to the electro-hydraulic servo valve 3.

[0018] Furthermore, the electromagnetic reversing valve 7 is a normally closed electromagnetic valve, which can ensure that the oil circuit is automatically closed in the event of an accidental power failure, keeping the mechanical structure in its original position and ensuring safety.

[0019] Furthermore, the hydraulic source 1 includes an oil tank, which is connected in sequence to a first filter, a hydraulic pump, a second check valve, and a second filter via an oil outlet pipeline. The hydraulic pump is connected in sequence to a second relief valve, a third filter, and the oil tank via a return oil pipeline.

[0020] The workflow of this invention is as follows:

[0021] (1) Filling control: such as Figure 2 As shown, when the filling process begins, the electromagnetic directional valve 7 is de-energized and disconnects its oil circuit. Simultaneously, the electro-hydraulic servo valve 3 is energized and its oil circuit opens. Hydraulic oil flows from port P1 to port A1, oil enters the lower chamber of the reset cylinder 8, and returns oil from the upper chamber. Hydraulic oil flows from port B1 to port T1, and the die completes the upward filling process under the action of the reset cylinder 8. During this process, the position sensor 9 monitors the piston position of the reset cylinder 8 and sends the signal to the controller. The controller programs and controls the displacement of the valve core in the electro-hydraulic servo valve 3 according to the signal, changing the flow rate, thereby controlling the position and speed of the piston in the reset cylinder 8, eliminating position errors, and making the actual displacement curve of the die more closely match the preset displacement curve.

[0022] (2) Suppression and control: such as Figure 3As shown, when the pressing process begins, the electro-hydraulic servo valve 3 is de-energized and disconnects its oil circuit, while the solenoid directional valve 7 is energized and opens its oil circuit. Hydraulic oil flows from port P2 to port A2, oil enters the upper chamber of the reset cylinder 8, and returns oil to the lower chamber. Hydraulic oil flows from port B2 to port T2, and the die is subjected to pressing force to complete the downward pressing process. During this process, the first overflow valve 4 provides back pressure on the return oil circuit. This back pressure prevents the mechanism from falling due to its own weight, but does not hinder the downward movement of the die under the pressing force. The pressure reducing valve 5 can reduce the pressure in the oil inlet circuit, providing low-pressure oil to the upper chamber of the reset cylinder 8, preventing the die from moving too quickly due to excessively high oil source pressure. The first one-way valve 6 can allow the piston of the reset cylinder 8 to move downward in one direction, preventing the piston from moving upward due to excessive pressure in the lower chamber of the reset cylinder 8 after the pressing force is removed, which would damage the product inside the die cavity, thus achieving the die holding function.

Claims

1. A servo control system for a powder molding machine die, characterized in that, The system includes a hydraulic power source (1), an accumulator (2), an electro-hydraulic servo valve (3), a first relief valve (4), a pressure reducing valve (5), a first check valve (6), a solenoid directional valve (7), a reset cylinder (8), and a position sensor (9). The oil outlet and return lines of the hydraulic power source (1) are connected to the P1 port and T1 port of the electro-hydraulic servo valve (3), respectively. The A1 port and B1 port of the electro-hydraulic servo valve (3) are connected to the lower oil port and upper oil port of the reset cylinder (8), respectively. The oil outlet and return lines of the hydraulic power source (1) are also connected to the pressure reducing valve (5) and the first relief valve (4), respectively. The pressure reducing valve (5) is connected to the first check valve (6). The oil inlet is connected, the first check valve (6) and the first relief valve (4) are connected to the P2 port and T2 port of the electromagnetic directional valve (7) respectively, and the A2 port and B2 port of the electromagnetic directional valve (7) are connected to the upper oil port and lower oil port of the reset cylinder (8) respectively; an accumulator (2) is provided between the hydraulic source (1) and the P1 port of the electro-hydraulic servo valve (3); a position sensor (9) is provided on the reset cylinder (8) to monitor the piston position of the reset cylinder (8) and send it to the controller. The controller is used to control the displacement of the valve core in the electro-hydraulic servo valve (3) and change the flow rate, thereby controlling the piston position and speed of the reset cylinder (8).

2. The powder forming machine die servo control system according to claim 1, characterized in that, (a) Filling control: The electro-hydraulic servo valve (3) is energized, the solenoid directional valve (7) is de-energized, the hydraulic oil flows from port P1 to port A1, the lower chamber of the reset cylinder (8) is filled with oil, the upper chamber is returned oil, the hydraulic oil flows from port B1 to port T1, and the die completes the upward filling process under the action of the reset cylinder (8); during this process, the position sensor (9) sends the piston position signal of the reset cylinder (8) to the controller, and the controller programs and controls the flow rate in the electro-hydraulic servo valve (3) according to the position signal, thereby controlling the piston position and speed of the reset cylinder (8) to complete the filling process; (b) Pressing control: When the electro-hydraulic servo valve (3) is de-energized, the electromagnetic reversing valve (7) is energized, and the hydraulic oil flows from port P2 to port A2. The upper chamber of the reset cylinder (8) receives oil, and the lower chamber returns oil. The hydraulic oil flows from port B2 to port T2. The die is subjected to pressing force and drives the piston of the reset cylinder (8) to move down to the designated position, thus completing the pressing process.

3. The powder forming machine die servo control system according to claim 1, characterized in that, The solenoid directional valve is a normally closed solenoid valve.

4. The powder forming machine die servo control system according to claim 1, characterized in that, The hydraulic power source includes an oil tank, which is connected in sequence to a first filter, a hydraulic pump, a second check valve, and a second filter via an oil outlet pipeline. The hydraulic pump is connected in sequence to a second relief valve, a third filter, and the oil tank via a return oil pipeline.

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