A sheet fixing mechanism located in the product forming area of ​​the mold parting surface

Abstract

The present invention provides a sheet fixing mechanism located in the product forming area of ​​the mold parting surface, comprising: a core, arranged on the movable mold parting surface or the fixed mold parting surface, the core having a forming surface, the forming surface including a plane parallel to the parting surface, the plane being used to cooperate with the plane of the product forming area on the opposite side of the core to clamp the sheet; a hydraulic cylinder, arranged on the movable mold or the fixed mold, the output shaft of the hydraulic cylinder driving the core to eject or retract; and a hydraulic system, connecting and controlling the hydraulic cylinder to perform actions under a set constant pressure and constant flow. The core of the sheet fixing mechanism can perform the dual functions of fixing the sheet and forming, and when the mold is closed, the core can maintain pressure to clamp the sheet under the drive of the hydraulic cylinder controlled by the hydraulic system, and at the same time retract with the mold, so that a wide sheet can slide into the mold cavity for molding, so that the mold can produce and process products with a deep cavity structure in the center area and a complex geometric shape around it.

Description

Technical Field

[0001] The present invention relates to the field of mold technology, and in particular to a sheet material fixing mechanism located in a product forming area of ​​a mold parting surface. Background Art

[0002] Thermoplastic organosheets are gaining increasing adoption within the industry, but due to processing limitations, mold structures are primarily designed for products with simple geometries, such as electrical boxes and battery enclosures. For fiberform processes (combining thermoforming and injection molding of organosheets into a single process step) or injection molding processes involving insert sheets, conventional solutions often use pin-point fastening within the injection mold. After infrared heating, the sheet transforms from a rigid sheet into a soft, cloth-like fabric. A robotic gripper then secures the sheet to pins in the mold through pre-defined holes in the sheet. This fastening method is limited in that it only works for products with simple geometries. It is ineffective for products with complex geometries surrounding a deep central cavity. This is because the soft sheet lacks the necessary space to slide and can tear during mold closing. Alternatively, existing solutions employ pin-type fastening methods, but these methods often leave marks on the softened sheet due to their limited contact area. These marks typically appear within the mold's exterior, making them unacceptable. For the sheets required for large-width products, this method cannot provide sufficient force to complete positioning. Summary of the Invention

[0003] The present invention is made to solve the above-mentioned problem, and its purpose is to provide a sheet material fixing mechanism located in the product forming area of ​​the mold parting surface.

[0004] The present invention provides a sheet fixing mechanism located in the product molding area of ​​the mold parting surface, wherein the mold includes a movable mold and a fixed mold, and the parting surface includes a movable mold parting surface and a fixed mold parting surface, and has the following characteristics: a core, which is arranged on the movable mold parting surface or the fixed mold parting surface, and the core has a molding surface, and the molding surface includes a plane parallel to the parting surface, and the plane is used to cooperate with the plane of the product molding area on the opposite side of the core to clamp the sheet; a hydraulic cylinder, which is arranged on the movable mold or the fixed mold and is located on the same side as the core, and the output shaft of the hydraulic cylinder drives the core to be ejected or retracted through a mechanical connection; and a hydraulic system, which connects and controls the hydraulic cylinder to perform actions under a set constant pressure and constant flow.

[0005] The sheet fixing mechanism provided by the present invention may also have the following features: the output shaft of the hydraulic cylinder and the core are connected by a push rod assembly, the push rod assembly includes a push rod connecting plate and a push rod connected to the push rod connecting plate, the push rod connecting plate is connected to the output shaft of the hydraulic cylinder, and the push rod is connected to the core.

[0006] The sheet fixing mechanism provided by the present invention may also have the following features: the hydraulic system includes a proportional valve, a hydraulic power source and a hydraulic power source pipeline, an oil tank and an oil tank pipeline, a first working pipeline, a second working pipeline, a pressure pipeline, a return oil pipeline, a first safety valve, a first one-way valve, and a second safety valve. The proportional valve has an A port, a B port, a P port, and a T port. The first working pipeline is respectively connected to the A port of the proportional valve and a working chamber of the hydraulic cylinder, the second working pipeline is respectively connected to the B port of the proportional valve and the other working chamber of the hydraulic cylinder, the pressure pipeline is respectively connected to the P port of the proportional valve and the hydraulic power source pipeline, the return oil pipeline is respectively connected to the T port of the proportional valve and the oil tank pipeline, the inlet and outlet of the first safety valve are respectively connected to the first working pipeline and the oil tank pipeline through pipelines, the first one-way valve and the second safety valve are arranged in parallel on the second working pipeline, and the outlet of the first one-way valve and the inlet of the second safety valve are both connected to the B port of the proportional valve.

[0007] Furthermore, the hydraulic power source is preferably an accumulator.

[0008] Furthermore, the first safety valve is a pilot-operated safety valve and its opening and closing are controlled by the pressure of the first working pipeline and the oil tank pipeline.

[0009] Furthermore, the second safety valve is a pilot-operated safety valve and its opening and closing is controlled by the pressure of the second working pipeline and the oil tank pipeline.

[0010] Furthermore, the hydraulic system also includes a second one-way valve, which is arranged on the oil tank pipeline to prevent other oil circuits from interfering with the hydraulic system.

[0011] Furthermore, the hydraulic system is provided on the injection molding machine and is a part of the hydraulic system of the injection molding machine.

[0012] Furthermore, a first pressure measuring point and a pressure sensor are provided on the first working pipeline, and a second pressure measuring point is provided on a portion of the second working pipeline connected to the inlet of the first one-way valve.

[0013] Furthermore, the hydraulic system also includes a control unit, which is connected to the proportional valve and is used to set a constant pressure and a constant flow of the hydraulic system and control the proportional valve to operate according to the set constant pressure and constant flow.

[0014] Functions and effects of the invention

[0015] According to the sheet fixing mechanism located in the product forming area of ​​the mold parting surface involved in the present invention, because the forming surface of the core includes a plane parallel to the parting surface, the hydraulic system can control the hydraulic cylinder to drive the core to eject under constant pressure and constant flow, so that the plane of the core can cooperate with the plane of the product forming area on the opposite side of the core to clamp the sheet, so the core of this sheet fixing mechanism can play the dual function of forming and fixing the sheet, and when the mold is closed, the core can maintain pressure to clamp the sheet under the drive of the hydraulic cylinder controlled by the hydraulic system, and at the same time retract with the mold, so that the wide sheet can slide into the mold cavity for molding, so that the mold can produce and process products with a deep cavity structure in the center area and complex geometric shapes around it. Among them, because the pressure and flow output to the hydraulic cylinder can be set in the hydraulic system, the movement speed and force of the core can be adjusted. In addition, this sheet fixing mechanism can also serve as an ejection mechanism to assist the ejector pin to eject the product after the mold is opened. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 1 is a schematic structural diagram of a sheet material fixing mechanism located in a product forming area on a mold parting surface in Example 1 of the present invention;

[0017] Figure 2 is a schematic structural diagram of the hydraulic system in Example 1 of the present invention;

[0018] Figure 3 This is a schematic diagram of a software interface of the control unit in Example 1 of the present invention;

[0019] Figure 4 Schematic diagram of the structure of the sheet fixing mechanism located in the product forming area of ​​the mold parting surface in Example 2 of the present invention.

[0020] Description of reference numerals:

[0021] 1. Movable mold parting surface; 2. Fixed mold parting surface; 3. Cavity; 10. Core; 10. Ejection position; 10. Retraction position; 11. Plane; 20. Hydraulic cylinder; 30. Hydraulic system; 31. Proportional valve; 32. Hydraulic power source; 33. Hydraulic power source pipeline; 34. Oil tank; 35. Oil tank pipeline; 36. First working pipeline; 37. Second working pipeline; 38. Pressure pipeline; 39. Oil return pipeline; 310. First safety valve; 311. First check valve; 312. Second safety valve; 313. Second check valve; 314. Pressure sensor; P1. First pressure measuring point; P2. Second pressure measuring point; 40. Push rod assembly; 41. Push rod connecting plate; 42. Push rod. DETAILED DESCRIPTION

[0022] In order to make the technical means, creative features, objectives and effects of the present invention easier to understand, the present invention is described in detail in the following embodiments with reference to the accompanying drawings.

[0023] Example 1

[0024] Figure 1 It is a structural diagram of the sheet fixing mechanism located in the product forming area of ​​the mold parting surface.

[0025] like Figure 1 As shown, this embodiment provides a sheet fixing mechanism located in the product forming area of ​​the mold parting surface, including a core 10, a hydraulic cylinder 20, and a hydraulic system.

[0026] The core 10 is arranged in the product molding area of ​​the movable mold parting surface 1. The core 10 has a molding surface that cooperates with the cavity 3 on the fixed mold parting surface 2. The molding surface includes a plane 11 parallel to the fixed mold parting surface 2. The plane 11 is not only used to cooperate with the cavity 3 to form the structure of the molded product, and the texture can be set on the plane 11 according to the structure of the product, but also used to cooperate with the plane of the product molding area on the opposite side of the core 10 to clamp the sheet.

[0027] The hydraulic cylinder 20 is disposed on the movable mold of the mold. The output shaft of the hydraulic cylinder 20 drives the core 10 to be ejected or retracted through a mechanical connection. The position of the core 10 when ejected is shown in the ejection position 10a, and the position of the core 10 when retracted is shown in the retraction position 10b. The number, position, and selection of the hydraulic cylinders 20 are set according to the actual conditions of the mold and the product. In this embodiment, there are multiple hydraulic cylinders 20. The output shafts of the multiple hydraulic cylinders 20 and the core 10 are connected by a push rod assembly 40. The push rod assembly 40 includes a push rod connecting plate 41 and multiple push rods 42 connected to the push rod connecting plate 41. The push rod connecting plate 41 is connected to the output shafts of the multiple hydraulic cylinders 20, and the multiple push rods 42 are connected to the core 10. By providing the push rod assembly 40 to connect the output shafts of the hydraulic cylinders 20 and the core 10, the transmission between the hydraulic cylinders 20 and the core 10 and the movement of the core 10 are made smoother and more reliable.

[0028] The hydraulic system is connected to the hydraulic cylinder 20 at access points A and B. The hydraulic system controls the hydraulic cylinder 20 to operate at a set constant pressure and flow rate. The hydraulic system can be installed in an injection molding machine, a hydraulic station, or other mechanical equipment. In this embodiment, the hydraulic system is installed in the injection molding machine as part of the machine's hydraulic system.

[0029] Figure 2 3 is a schematic structural diagram of the hydraulic system 30.

[0030] like Figure 2 As shown, the hydraulic system 30 includes a proportional valve 31, a hydraulic power source 32 and a hydraulic power source pipeline 33, an oil tank 34 and an oil tank pipeline 35, a first working pipeline 36, a second working pipeline 37, a pressure pipeline 38, a return oil pipeline 39, a first safety valve 310, a first one-way valve 311, and a second safety valve 312.

[0031] The proportional valve 31 ensures that the hydraulic system 30 operates at a constant pressure and flow rate. In this embodiment, the proportional valve 31 is a three-position, four-way proportional valve having ports A, B, P, and T. Ports A and B are both working oil ports, connected to a first working line 36 and a second working line 37, respectively. These first and second working lines 36 and 37 are used to connect to the hydraulic cylinder 20, as shown at access points A and B, to control the movement of the hydraulic cylinder 20. Port P is the oil inlet and is connected to the hydraulic power source line 33 via a pressure line 38. Port T is the oil return port and is connected to the tank line 35 via a return line 39.

[0032] Hydraulic power source 32 is used to provide hydraulic power. Hydraulic power source 32 can be a hydraulic pump, accumulator, or other device capable of providing hydraulic energy. Oil tank 34 is used to store hydraulic oil and collect return oil. In this embodiment, hydraulic system 30 is installed on the injection molding machine, and hydraulic power source 32 is an accumulator. Accumulators are conventionally used to increase the injection speed of injection molding machines. However, in this embodiment, an accumulator is used to provide hydraulic power for hydraulic system 30, allowing it to be separated from the oil circuits of other hydraulic cores on the injection molding machine, thereby preventing them from affecting their operation.

[0033] The inlet and outlet of the first safety valve 310 are connected to the first working line 36 and the tank line 35, respectively, via pipelines. The first safety valve 310 prevents excessive pressure in the first working line 36, providing safety protection for the hydraulic system 30. When the pressure in the first working line 36 exceeds a specified value, the first safety valve 310 opens, allowing excess hydraulic oil in the first working line 36 to flow back to the tank 34 through the tank line 35, thereby preventing accidents in the hydraulic system 30 caused by excessive pressure. In this embodiment, the first safety valve 310 is a pilot-operated safety valve, and its opening and closing are controlled by the pressure in the first working line 36 and the tank line 35. Compared to conventional safety valves, pilot-operated safety valves offer better sealing, easily meet the required opening and closing pressure differential, and provide more accurate and sensitive operation, a long service life, and stable reliability.

[0034] A first check valve 311 and a second safety valve 312 are installed in parallel on the second working line 37. The outlet of the first check valve 311 is connected to port B of the proportional valve 31, preventing reverse flow of hydraulic oil. The inlet of the second safety valve 312 is connected to port B of the proportional valve 31. The second safety valve 312 prevents excessive pressure in the second working line 37, providing safety protection for the hydraulic system 30. When the pressure in the second working line 37 exceeds a specified value, the second safety valve 312 opens, allowing excess hydraulic oil in the second working line 37 to flow back to the tank 34 through the tank line 35, thereby preventing accidents caused by excessive pressure in the hydraulic system 30. In this embodiment, the second safety valve 312 is a pilot-operated safety valve, and its opening and closing are controlled by the pressure in the second working line 37 and the tank line 35. The second safety valve 312 also features excellent sealing, precise and sensitive operation, a long service life, and stable and reliable operation.

[0035] This ensures that when the required mold closing speed is very high (depending on the machine model, the maximum mold plate operating speed of the equipment is 590-800 mm / s), the hydraulic system 30 can still drive the hydraulic cylinder 20 to perform the action safely, thereby ensuring the Fiberform process window.

[0036] In order to prevent other oil circuits from interfering with the hydraulic system 30 , the hydraulic system 30 further includes a second one-way valve 313 . The second one-way valve 313 is provided on the oil tank pipeline 35 to prevent hydraulic oil from other oil circuits from entering the hydraulic system 30 .

[0037] In order to realize manual detection and real-time monitoring of the pipeline pressure of the hydraulic system 30 by sensors, in this embodiment, a first pressure measuring point P1 and a pressure sensor 314 are provided on the first working pipeline 36. The first pressure measuring point P1 can be used to manually detect the pressure of the first working pipeline 36, and the pressure sensor 314 is used to monitor the pressure of the first working pipeline 36 in real time; a second pressure measuring point P2 is provided on the second working pipeline 37. More specifically, the second pressure measuring point P2 is set on the part of the second working pipeline 37 connected to the inlet of the first one-way valve 311, and the second pressure measuring point P2 is used to manually detect the pressure of the second working pipeline 37.

[0038] To achieve automated control, the sheet material securing mechanism further includes a control unit connected to the proportional valve 31. The control unit is configured to set a constant pressure and flow rate for the hydraulic system 30 and control the proportional valve 31 to operate at the set constant pressure and flow rate. In this embodiment, the control unit comprises a host computer and a slave computer. The host computer is equipped with conventional hydraulic system control software, which can directly send control commands to the slave computer and set specific parameters of the hydraulic system. Figure 3The software interface of the hydraulic system control software is shown. It can be seen that in this embodiment, the constant pressure and constant flow of the hydraulic system 30 are set to 80 bar and 60 L / min, respectively. The lower computer controls the proportional valve 31 to operate according to the constant pressure and constant flow set by the upper computer. The lower computer is a PLC. In other embodiments, the lower computer can also be a single-chip microcomputer.

[0039] Taking the mold production process in the Fiberform process as an example, the working principle of this sheet fixing mechanism is as follows:

[0040] Before the mold is closed, core 10 is ejected to assist in demolding, at which point it is in ejection position 10a. As the mold begins to close, all cores, including core 10, retract, and core 10 is in retracted position 10b. The mold then closes to the intermediate position according to the injection molding machine's settings and stops.

[0041] Then, the robot delivers the heated and thoroughly heated sheet to the corresponding position at the parting surface. Driven by the hydraulic system 30, the hydraulic cylinder 20 ejects the core 10 to the ejection position 10a. At this time, the plane 11 of the core 10 cooperates with the plane of the product molding area on the opposite side of the core 10 to clamp the sheet in place. The accumulator of the hydraulic system 30 provides hydraulic power, and the hydraulic system 30 controls the hydraulic oil in the pipeline through the proportional valve 31 to output at a set constant pressure and constant flow, ensuring that the movement speed and force of the core 10 driven by the hydraulic cylinder 20 are sufficient to clamp the sheet well.

[0042] Afterwards, the mold continues to close and the sheet is hot-formed. During this process, the hydraulic system 30 ensures that the pressure and flow of the output hydraulic oil are constant through the proportional valve 31, so that the core 10 maintains the clamping of the sheet under the drive of the hydraulic cylinder 20. At the same time, it is pressed back to the retracted position 10b as the mold closing process progresses. The hydraulic oil in the hydraulic system 30 that exceeds the set constant pressure and constant flow flows back to the oil tank 34 through the first safety valve 310 and / or the second safety valve 312. The clamped part of the sheet will be hot-pressed with the geometric shape and texture of the molding surface of the core 10, and the part of the sheet located outside the product molding area of ​​the parting surface will slide into the mold cavity for molding.

[0043] Once the mold is closed, the clamping force is applied to complete the thermoforming of the entire sheet. After injection and holding pressure, the plastic melt forms the product's reinforcements and other geometric structures, then enters a cooling period. After cooling, the clamping force is reduced, and the mold opens. Once the mold is fully opened, the hydraulic system 30 controls the hydraulic cylinder 20 to drive the core 10 to the ejection position 10a, assisting the mold's ejector pins in ejecting the product. After ejection is complete, the robot can remove the part.

[0044] Example 2

[0045] Figure 4 It is a structural diagram of the sheet fixing mechanism located in the product forming area of ​​the mold parting surface.

[0046] like Figure 4 As shown, this embodiment provides a sheet material securing mechanism located within the product forming area of ​​the mold parting surface, comprising a core 10, a hydraulic cylinder 20, and a hydraulic system. This differs from Example 1 in that core 10 is located within the product forming area of ​​the fixed mold parting surface 2 and engages with the cavity on the movable mold parting surface 1. The hydraulic cylinder 20 and push rod assembly 40 are located on the fixed mold. All other components are identical to those of Example 1 and are not further described.

[0047] Functions and Effects of the Embodiments

[0048] According to the sheet material fixing mechanism located within the product forming area of ​​the mold parting surface involved in the above-mentioned embodiment, because the forming surface of the core includes a plane parallel to the parting surface, the hydraulic system can control the hydraulic cylinder to drive the core out at a constant pressure and constant flow rate, so that the plane of the core can cooperate with the plane of the product forming area on the opposite side of the core to clamp the sheet material. Therefore, the core of this sheet material fixing mechanism can perform the dual functions of forming and fixing the sheet material. Moreover, when the mold is closed, the core can maintain pressure to clamp the sheet material under the drive of the hydraulic cylinder controlled by the hydraulic system, and at the same time retract with the mold, so that the wide sheet material can slide into the mold cavity for molding, thereby enabling the mold to produce and process products with a deep cavity structure in the center area and complex geometric shapes around it. Among them, because the pressure and flow output to the hydraulic cylinder can be set in the hydraulic system, the movement speed and force of the core can be adjusted. In addition, this sheet material fixing mechanism can also serve as an ejection mechanism, assisting the ejector pin to eject the product after the mold is opened.

[0049] The output shaft of the hydraulic cylinder and the core can be connected via a push rod assembly, which makes the transmission between the hydraulic cylinder and the core and the movement of the core smoother and more reliable.

[0050] The hydraulic system includes a proportional valve, a hydraulic power source and its piping, an oil tank and its piping, a first safety valve, a first check valve, and a second safety valve. The proportional valve ensures the hydraulic system operates at a set constant pressure and flow rate. The hydraulic power source provides hydraulic power, and the oil tank stores hydraulic oil and collects return oil. The first and second safety valves, respectively, prevent excessive pressure in the two working lines connected to the proportional valve, providing safety protection. This ensures constant output pressure and flow, allowing the hydraulic cylinder to operate under guaranteed pressure.

[0051] Furthermore, the hydraulic system can be installed on the injection molding machine and form part of the machine's hydraulic system. The hydraulic power source is preferably an accumulator. Using the accumulator to provide the hydraulic power for the hydraulic system allows the hydraulic system to be separated from other hydraulic core oil circuits on the injection molding machine, thereby preventing interference with other core operations. Furthermore, even when high mold closing speeds are required, the hydraulic system can still safely drive the hydraulic cylinders to operate, thereby maintaining the Fiberform process window. A second check valve can be installed on the oil tank line to prevent other oil circuits from interfering with the hydraulic system.

[0052] Furthermore, the first and second safety valves are preferably pilot-operated safety valves, characterized by good sealing, precise and sensitive operation, long service life, and stable and reliable operation. The first and second working pipelines may be provided with first and second pressure measuring points, respectively, for manual pressure detection. The first working pipeline may also be provided with a pressure sensor for real-time pressure monitoring, thereby enabling automated monitoring of pipeline pressure.

[0053] Furthermore, the hydraulic system also includes a control unit for realizing automatic control, through which the constant pressure and constant flow of the hydraulic system can be set and the proportional valve can be controlled to operate according to the set constant pressure and constant flow.

[0054] The above embodiments are preferred examples of the present invention and are not intended to limit the scope of protection of the present invention.

Claims

1. A sheet material fixing mechanism located within the product forming area of ​​a mold parting surface, used in a Fiberform process, wherein the mold comprises a movable mold and a fixed mold, the parting surface comprises a movable mold parting surface and a fixed mold parting surface, and the mold is used to produce a product having a deep cavity structure in the center area and a complex geometric shape around the periphery, characterized in that: include: A core is provided on the movable mold parting surface or the fixed mold parting surface, the core having a molding surface, the molding surface including a plane parallel to the parting surface, the plane being used to cooperate with the plane of the product molding area on the opposite side of the core to clamp the sheet; a hydraulic cylinder, disposed on the movable mold or the fixed mold and located on the same side as the core, wherein the output shaft of the hydraulic cylinder drives the core to be ejected or retracted through a mechanical connection; and The hydraulic system connects and controls the hydraulic cylinder to perform actions under set constant pressure and constant flow, The plane can be textured according to the structure of the product. The hydraulic system includes a proportional valve, a hydraulic power source and a hydraulic power source pipeline, an oil tank and an oil tank pipeline, a first working pipeline, a second working pipeline, a pressure pipeline, an oil return pipeline, a first safety valve, a first check valve, and a second safety valve. The proportional valve has port A, port B, port P and port T. The first working pipeline is connected to the A port of the proportional valve and a working chamber of the hydraulic cylinder respectively. The second working pipeline is connected to the B port of the proportional valve and the other working chamber of the hydraulic cylinder respectively. The pressure pipeline is connected to the P port of the proportional valve and the hydraulic power source pipeline respectively. The oil return pipeline is connected to the T port of the proportional valve and the oil tank pipeline respectively. The inlet and outlet of the first safety valve are connected to the first working pipeline and the fuel tank pipeline respectively through pipelines. The first one-way valve and the second safety valve are arranged in parallel on the second working pipeline, and the outlet of the first one-way valve and the inlet of the second safety valve are both connected to the B port of the proportional valve. The first working pipeline is provided with a first pressure measuring point and a pressure sensor, and the second working pipeline is provided with a second pressure measuring point on a portion connected to the inlet of the first one-way valve. The hydraulic system further includes a second one-way valve, which is arranged on the oil tank pipeline and is used to prevent other oil circuits from interfering with the hydraulic system.

2. The sheet material fixing mechanism according to claim 1, characterized in that: in, The output shaft of the hydraulic cylinder is connected to the core via a push rod assembly. The push rod assembly includes a push rod connecting plate and a push rod connected to the push rod connecting plate. The push rod connecting plate is connected to the output shaft of the hydraulic cylinder. The push rod is connected to the core.

3. The sheet material fixing mechanism according to claim 1, characterized in that: in, The hydraulic power source is an accumulator.

4. The sheet material fixing mechanism according to claim 1, characterized in that: in, The first safety valve is a pilot-operated safety valve, and its opening and closing are controlled by the pressure of the first working pipeline and the oil tank pipeline.

5. The sheet material fixing mechanism according to claim 1, characterized in that: in, The second safety valve is a pilot-operated safety valve and its opening and closing are controlled by the pressure of the second working pipeline and the fuel tank pipeline.

6. The sheet material fixing mechanism according to claim 1, characterized in that: in, The hydraulic system is arranged on an injection molding machine and is a part of the hydraulic system of the injection molding machine.

7. The sheet material fixing mechanism according to any one of claims 1 to 6, characterized in that: in, The hydraulic system further comprises a control unit, The control unit is connected to the proportional valve and is used to set a constant pressure and a constant flow of the hydraulic system and control the proportional valve to operate according to the set constant pressure and constant flow.

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