WO2024040943A1

WO2024040943A1 - Injection molding machine structure precisely controlled via digital hydraulic oil cylinder

Info

Publication number: WO2024040943A1
Application number: PCT/CN2023/081892
Authority: WO
Inventors: 李君�; 张贤宝; 林娅丹
Original assignee: 西诺控股集团有限公司
Priority date: 2022-08-25
Filing date: 2023-03-16
Publication date: 2024-02-29
Also published as: CN117124553A

Abstract

An injection molding machine structure precisely controlled via a digital hydraulic oil cylinder (5), relating to injection molding machine structures, and comprising an injection molding head (4) matched with a mold, and a digital hydraulic oil cylinder (5) used for opening and closing the mold. The digital hydraulic oil cylinder (5) comprises a driving motor (6), a controller, a valve body portion (7), and a cylinder body portion (8). The valve body portion (7) is provided with a liquid inlet (9), a liquid return port (10), an extending liquid inlet (11), and a retracting liquid outlet (12). The digital hydraulic oil cylinder (5) achieves direct mechanical closed-loop feedback, the control precision is high, the response is fast, and the higher the precision of the mold extending position of the injection molding machine is, the more stable a produced product is, thereby solving the problems in the prior art of low response speed and insufficient control precision caused by using common cylinders to control the opening and closing of molds in injection molding machines.

Description

An injection molding machine structure precisely controlled by a digital hydraulic cylinder

Technical field

The present invention relates to an injection molding machine structure, and in particular to an injection molding machine structure precisely controlled by a digital hydraulic cylinder.

Background technique

The frequency response speed of any system is inversely proportional to the cumulative lag time of all its links. In the existing technology, the injection molding machine uses PLC + valve + ordinary hydraulic cylinder to control the opening and closing of the mold. The hydraulic cylinder is connected to the front plate of the injection platform of the injection molding machine. The front end of the piston rod is fixed with a nut on the injection molding machine head plate. The piston rod of the oil cylinder reciprocates. , to realize the forward and backward movement of the injection molding machine. In this process, since the external indirect closed-loop feedback of PLC + valve + ordinary hydraulic cylinder + position sensor is used, the control accuracy is relatively low and the response is relatively slow.

For example, "a single-stage preform injection molding machine injection platform mechanism" disclosed in Chinese patent documents, its announcement number is CN113752463A, includes a base, the upper surface of the base is slidably connected to a mounting base, and the top of the mounting base is mounted with a material Bucket, the front of the mounting base is provided with an injection molding pass, a heating sleeve is installed on the arc surface of the injection molding pass, a conveying screw is installed inside the injection molding pass, and the tail end of the conveying screw protrudes from the rear end of the mounting base. , a motor is slidably connected to the rear end of the mounting base, the output end of the motor is connected to the tail end of the conveying screw, and injection hydraulic cylinders are symmetrically provided on both sides of the mounting base; the disadvantage of this invention is that it When controlling the opening and closing of the mold, it is necessary to detect the position of the valve body through a position sensor and respond to the PLC system, and then drive the opening and closing of the mold of the injection molding machine through the movement of the piston rod of the hydraulic control cylinder. The response of the control process is slow, resulting in insufficient control accuracy.

Contents of the invention

The present invention is to overcome the problems in the existing technology that use ordinary oil cylinders to control the opening and closing of the injection molding machine, resulting in slow response speed and insufficient control accuracy. It provides an injection molding machine structure that is precisely controlled by a digital hydraulic cylinder, which can speed up the response. speed, thereby making the position accuracy of the injection head higher, thereby improving the quality of the product.

In order to achieve the above objects, the present invention adopts the following technical solutions:

The present invention is an injection molding machine structure precisely controlled by a digital hydraulic cylinder, including an injection head adapted to the mold, and a digital hydraulic cylinder for opening and closing the mold. The digital hydraulic cylinder includes a drive motor, a controller, and a valve body. The valve body part is equipped with a liquid inlet, a liquid return port, an advance liquid outlet and a retreat liquid outlet. The valve body is equipped with a valve sleeve and a valve stem. The cylinder body is equipped with a piston chamber and a piston. , both ends of the piston cavity are provided with a carry liquid inlet and a retreat liquid inlet. The carry liquid inlet and the carry liquid outlet are connected by a liquid inlet pipe, and the retreat liquid inlet and the retreat liquid outlet are connected by a liquid withdrawal pipe. connect.

This application uses a digital hydraulic cylinder to provide direct mechanical closed-loop feedback, with high control accuracy and fast response. The higher the accuracy of the ejection position of the injection molding machine and mold, the more stable the product produced; the digital hydraulic cylinder combines: valve, cylinder, feedback and drive control The ingenious combination makes it a whole and appears as an independent device to the outside world. Users do not need to be inertial about its internal structure and characteristics. They can easily master the use after only understanding the fixed relationship between input and output. Moreover, this one-piece digital cylinder has good integrity and It has strong anti-pollution ability, high precision, stability and reliability, and low overall cost; the digital hydraulic cylinder already has position closed-loop capability internally, so it no longer requires additional sensors for closed-loop control when achieving precise micron-level repeated positioning. Even in terms of speed control, due to the digitization of its movement characteristics, the pulse frequency corresponds to the movement speed characteristics of the digital hydraulic cylinder, which eliminates the need to use sensors to implement closed-loop control.

Preferably, it also includes a hopper, an injection molding pass, and a heating sleeve located outside the injection molding pass. A spiral conveying structure is provided inside the injection molding pass. The spiral conveying structure is provided with a pressure feedback structure near the mold; through the pressure feedback structure , the pressure of transporting injection molding materials in the injection molding channel can be detected in time, and then the melting condition of the injection molding material can be judged. If the detected pressure exceeds the standard value, it means that the injection molding material in the injection molding channel has not completely melted, resulting in greater resistance to transportation, and The corresponding signal is fed back to the controller through the pressure feedback structure, which can quickly detach the injection head from the mold to prevent incompletely melted material from entering the mold, resulting in unqualified product quality; when the injection head is detached from the mold , the heating sleeve still heats the material in the injection head. When the injection material is completely melted, part of the injection material at the end of the injection head flows back, causing the pressure at the pressure feedback structure to decrease again, thereby controlling the reset of the mold.

Preferably, the spiral conveying structure includes a fixed conveying structure and a feedback conveying structure that can rotate synchronously. The pressure feedback structure includes a pressure sensor. The pressure sensor is installed at one end of the feedback conveying structure; when the injection molding material in the injection molding pass is not completely melted, due to the With greater resistance, the pressure on the pressure sensor increases and the corresponding signal is fed back to the controller. When the injection molding material is completely melted, the pressure generated by the spiral conveying structure at one end of the injection molding channel close to the hopper is smaller. Since at one end close to the hopper, the injection molding material in the injection molding channel will not be completely melted under normal circumstances, this structure reduces the sensing range of the pressure feedback, thereby improving the sensing accuracy.

Preferably, the feedback conveying structure includes a guide rod portion that passes through the interior of the fixed conveying structure, a guide bar is provided on the outside of the guide bar portion, and a guide groove adapted to the guide bar is provided inside the fixed conveying structure; this structure allows The feedback conveying structure can have a certain degree of freedom in the axial direction, thereby ensuring that the pressure can be detected through the axial displacement.

Preferably, the spiral conveying structure includes a spiral conveying groove, and the length of the spiral conveying groove on the feedback conveying structure accounts for 1/5-1/2 of the total length of the spiral conveying groove; if the length of the feedback conveying structure is relatively too small, it may cause the system to There is no time to respond, and the incompletely melted injection molding material has already entered the mold; if the length of the feedback conveying structure is relatively long, the sensing range of the pressure feedback will increase.

Preferably, the injection molding machine structure also includes a conveying motor for driving the spiral conveying structure. The driving motor is a double-ended shaft motor. One end of the driving motor is connected to the valve stem, and the other end is connected to the conveying clutch structure. The conveying clutch structure It includes a clutch and a clutch transmission structure. One end of the clutch is connected to the output shaft of the conveyor motor, and the other end is connected to the screw conveyor. Structural connection; when the drive motor controls the injection head to separate from the mold, it also drives the clutch to move, thereby separating the spiral conveyor structure from the conveyor motor, causing the spiral conveyor structure to suspend conveying, preventing the material near the mold in the injection molding from being continuously pressurized. When the driving motor controls the mold to reset, it also causes the screw conveying structure and the conveying motor to cooperate again, causing the screw conveying structure to restart conveying.

Preferably, the spiral conveying structure includes a rotating shaft and a spiral piece installed outside the rotating shaft. The spiral piece forms a spiral conveying groove outside the rotating shaft. The outer diameter of the rotating shaft on the feedback conveying structure gradually increases in the direction toward the mold; this structure makes The feedback conveying structure puts the injection molding material under increasing pressure when conveying it. Once the material is not completely melted, it is more likely to get stuck near the mold in the feedback conveying structure. In the process of continuing to melt, once the material is completely melted, , due to the high pressure near the mold, part of the material will flow back, causing the pressure on the pressure sensor to gradually recover; this structure ensures the reliability of the feedback.

Therefore, the present invention has the following beneficial effects: (1) to speed up the response speed, thereby making the position accuracy of the injection molding head higher, thereby improving the quality of the product; (2) when part of the injection molding material in the injection molding barrel is not completely melted, it can Exit the injection molding head to prevent incompletely melted material from entering the mold or completely blocking the injection molding head. After the injection molding head exits and the injection molding material is completely re-melted, the injection molding head can be reset again.

Description of drawings

Figure 1 is a front structural schematic diagram of the present invention.

Figure 2 is a schematic cross-sectional structural view of the digital hydraulic cylinder of the present invention.

Figure 3 is a partially enlarged view of the partial structure of Figure 2 of the digital hydraulic cylinder of the present invention.

Figure 4 is a schematic cross-sectional structural view of the injection molding barrel of the present invention.

Figure 5 is a schematic cross-sectional structural view of the clutch of the present invention.

In the picture: 1. Hopper 2. Injection barrel 3. Heating sleeve 4. Injection head 5. Digital hydraulic cylinder 6. Drive motor 7. Valve body 8. Cylinder 9. Liquid inlet 10. Liquid return port 11. Advance liquid outlet 12, Retreat liquid outlet 13, Piston chamber 14, Piston 15, Liquid inlet pipe 16, Liquid withdrawal pipe 17, Fixed conveying structure 18, Feedback conveying structure 19, Pressure sensor 20, Guide rod part 21, Conveying motor 22. Clutch 23. Clutch transmission structure 24. Rotating shaft 25. Spiral conveyor groove 26. Clutch wheel 27. Clutch lever 28. Coupling 29. Side limit ribs 30. Balls.

Detailed ways

The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments.

In the embodiment shown in Figures 1-5, an injection molding machine structure precisely controlled by a digital hydraulic cylinder includes a hopper 1, an injection barrel 2, a heating sleeve 3 covering the outside of the injection barrel, and a heating sleeve adapted to the mold. Injection head 4, as well as for opening and closing the mold The digital hydraulic cylinder 5 includes a drive motor 6, a controller, a valve body 7 and a cylinder 8. The valve body is provided with a liquid inlet 9, a liquid return port 10, and a liquid inlet port 11. and a retreat liquid outlet 12. A valve sleeve and a valve stem are installed in the valve body. There are a piston chamber 13 and a piston 14 in the cylinder body. Both ends of the piston chamber are provided with a carry liquid inlet and a retreat liquid inlet. The carry liquid inlet The liquid inlet and the inlet outlet are connected by a liquid inlet pipe 15, and the retreat liquid inlet and the liquid outlet are connected by a drain pipe 16; the valve stem is a ball screw, and the valve sleeve is installed on the ball screw. The nut sleeve on the stem, the structure of the valve sleeve is the existing technology, the drive motor is a servo motor or a stepper motor, when the drive motor rotates, the valve sleeve moves in the axial direction of the valve stem; according to the rotation direction of the drive motor, The delivery direction of hydraulic oil is different. When the drive motor rotates forward, the liquid inlet and the advance liquid outlet are connected, and the liquid return port and the retreat liquid outlet are connected. The hydraulic oil enters the cylinder through the liquid inlet pipe, causing the piston to push the mold. Move towards the direction of the injection molding head. After the injection molding head opens the valve port in the mold, the digital hydraulic cylinder stops moving and completes the tracking of the electronically controlled stepper motor or servo motor angle when the hydraulic cylinder moves linearly. In the process, torque amplification is achieved. ; When the drive motor rotates in the reverse direction, the liquid inlet and the retreat liquid outlet are connected, and the liquid return port and the advance liquid outlet are connected. The hydraulic oil enters the cylinder through the liquid retreat pipe, causing the piston to push the mold away from the injection head.

The injection molding tunnel is provided with a spiral conveying structure, and the spiral conveying structure is provided with a pressure feedback structure near the mold; the spiral conveying structure includes a fixed conveying structure 17 and a feedback conveying structure 18 that can rotate synchronously, and the pressure feedback structure includes a pressure sensor 19. The pressure sensor is installed at one end of the feedback conveying structure; the feedback conveying structure includes a guide rod part 20, which passes through the inside of the fixed conveying structure. There are guide ribs on the outside of the guide rod part, and there are guide ribs inside the fixed conveying structure. Equipped with guide trough; the spiral conveyor structure includes a spiral conveyor trough, and the length of the spiral conveyor trough on the feedback conveyor structure accounts for 2/5 of the total length of the spiral conveyor trough.

The structure of the injection molding machine also includes a conveying motor 21 for driving the spiral conveying structure. The driving motor is a double-ended shaft motor. One end of the driving motor is connected to the valve stem, and the other end is connected to the conveying clutch structure. The conveying clutch structure includes a clutch. 22 and a clutch transmission structure 23. One end of the clutch is connected to the output shaft of the conveying motor, and the other end is connected to the spiral conveying structure; the spiral conveying structure includes a rotating shaft 24 and a spiral piece installed on the outside of the rotating shaft, and the spiral piece is on the outside of the rotating shaft. A spiral conveying groove 25 is formed, and the outer diameter of the rotating shaft on the feedback conveying structure gradually increases in the direction toward the mold; the clutch transmission structure includes a clutch screw rod and a clutch slider, and a push rod is used between the clutch slider and the clutch. Connection; the clutch is provided with a clutch wheel 26, the clutch wheel is provided with a first clutch tooth on the side facing the spiral conveying structure, and one end of the rotating shaft is provided with a second clutch tooth that meshes with the first clutch tooth; clutch The wheel is connected to a clutch lever 27 on the side facing away from the spiral conveying structure. One end of the clutch lever is connected to the output shaft of the conveying motor through a coupling 28. The clutch lever is circumferentially connected to the coupling through a side limit rib 29. limit; the inside of the clutch is also provided with a ball 30 that contacts the outside of the coupling.

During the entire injection molding process, through the pressure feedback structure, the pressure of the injection molding material transported in the injection molding tunnel can be detected instantly, and the melting condition of the injection molding material can be judged. If the detected pressure exceeds the standard value, it means that the injection molding in the injection molding The material is not completely melted, resulting in greater resistance to transportation. The corresponding signal is fed back to the controller through the pressure feedback structure, which can quickly detach the injection head from the mold to prevent incompletely melted material from entering the mold and causing product damage. The quality is unqualified; when the injection head is disconnected from the mold, the other end of the drive motor is also driving the clutch transmission structure to move, causing the clutch slider to move toward the conveying motor side; when the clutch slider moves, the clutch is pushed through the push rod. Move towards the conveying motor side, thereby separating the rotating shaft from the clutch wheel. At this time, the clutch wheel is in an idling state, and the spiral conveying structure no longer continues to push the injection molding material to prevent the pressure in the injection molding barrel from further increasing. At the same time, the heating sleeve still maintains the injection molding material. After the injection molding material is completely melted, the part of the injection molding material near the mold side of the injection molding barrel will flow back toward the conveying motor side, causing the pressure of the feedback conveying structure to decrease; when the detected pressure is less than the set value, it means that the injection molding in the injection barrel is The material has been completely melted. At this time, the drive motor once again drives the mold to cooperate with the injection head, and at the same time makes the clutch wheel cooperate with the rotating shaft. The injection molding process and the screw conveying process are restarted at the same time.

Claims

An injection molding machine structure precisely controlled by a digital hydraulic cylinder, which is characterized by including an injection head adapted to the mold, and a digital hydraulic cylinder for opening and closing the mold. The digital hydraulic cylinder includes a drive motor, a controller, and a valve. body and cylinder. The valve body is equipped with a liquid inlet, a liquid return port, an advance liquid outlet and a retreat liquid outlet. The valve body is equipped with a valve sleeve and valve stem. The cylinder body is equipped with a piston cavity and a valve stem. The piston has a carry liquid inlet and a retreat liquid inlet at both ends of the piston cavity. The carry liquid inlet and the carry liquid outlet are connected by a liquid inlet pipe. The retreat liquid inlet and the retreat liquid outlet are connected by a liquid withdrawal pipe. Pipe connections.
An injection molding machine structure precisely controlled by a digital hydraulic cylinder according to claim 1, characterized in that it also includes a hopper, an injection molding pass, and a heating sleeve located outside the injection molding pass, and a spiral conveying structure is provided inside the injection molding pass. The spiral conveying structure is equipped with a pressure feedback structure close to the mold.
An injection molding machine structure precisely controlled by a digital hydraulic cylinder according to claim 2, characterized in that the spiral conveying structure includes a synchronously rotatable fixed conveying structure and a feedback conveying structure, the pressure feedback structure includes a pressure sensor, and the pressure sensor is installed at one end of the feedback delivery structure.
An injection molding machine structure precisely controlled by a digital hydraulic cylinder according to claim 3, characterized in that the feedback conveying structure includes a guide rod part, the guide rod part passes through the inside of the fixed conveying structure, and the guide rod part is provided with Guide ribs, the fixed conveying structure is equipped with guide grooves that match the guide ribs.
An injection molding machine structure precisely controlled by a digital hydraulic cylinder according to claim 2, characterized in that the spiral conveying structure includes a spiral conveying groove, and the length of the spiral conveying groove on the feedback conveying structure accounts for 1% of the total length of the spiral conveying groove. /5-1/2.
An injection molding machine structure precisely controlled by a digital hydraulic cylinder according to claim 2, characterized in that the injection molding machine structure further includes a conveying motor for driving the spiral conveying structure, and the driving motor is a double-headed shaft motor. One end of the motor is connected to the valve stem, and the other end is connected to the conveying clutch structure. The conveying clutch structure includes a clutch and a clutch transmission structure. One end of the clutch is connected to the output shaft of the conveying motor, and the other end is connected to the spiral conveying structure.
An injection molding machine structure precisely controlled by a digital hydraulic cylinder according to claim 3, characterized in that the spiral conveying structure includes a rotating shaft and a spiral plate installed outside the rotating shaft, and the spiral plate forms a spiral conveying groove outside the rotating shaft, The outer diameter of the rotating shaft on the feedback conveying structure gradually increases toward the mold.