Composite material foam forming hydraulic machine and forming control method

Abstract

The invention relates to the technical field of composite material foaming forming, in particular to a composite material foaming forming hydraulic machine and a forming control method. The method comprises the following steps that a feeding trolley drives a lower die to make contact with a fixed pressing head; pressing heads are fed, the pressing heads are moved forwards, the horizontal pressing heads on the two sides horizontally reach set positions and are locked, and die assembly is completed; heating the mold to a set temperature and preserving heat, and injecting the composite material into the mold to wait for foam forming; locking force generated by the upper pressing head, the forward-moving pressing head and the horizontal pressing heads on the two sides is matched with foaming force of the composite material in a self-adaptive mode, and it is guaranteed that the mold does not generate foaming bulging displacement; and after foam forming is finished, the locking device is opened, and the feeding trolley drives the mold to exit from the foam forming hydraulic machine body. According to the method and system, it can be guaranteed that the mold does not generate foaming bulging displacement, the appearance size and surface quality of the product are guaranteed, and the method and system can be suitable for molds and products of different sizes.

Description

Technical Field

[0001] The invention relates to the technical field of composite material foaming and forming, in particular to a composite material foaming and forming hydraulic press and a forming control method. Background Art

[0002] With the rapid development of my country's aviation industry, new processes for forming composite materials such as aviation carbon fiber are emerging in an endless stream. The demand for the foaming and pressing process of carbon fiber thermoplastic composite sandwiches such as aviation tail wings is becoming more and more urgent. Traditional processes are mostly hot autoclaves and manual hand lay-up ovens, which have high energy consumption, complex manual operations, and low product qualification rates. In addition, since the locking force of the pressure head remains unchanged during the foaming process of the foamed body, the foaming force generated by the foaming of the composite material will cause the mold to move, thereby affecting the product's appearance and size and surface quality. Summary of the invention

[0003] The technical problem to be solved by the present invention is to provide a composite material foaming hydraulic press and a forming control method, which has a high degree of automation, saves manpower, and has high production efficiency. In the foaming process, the locking force generated by the upper pressure head, the forward pressure head and the horizontal pressure heads on both sides adaptively matches the foaming force of the composite material to ensure that the mold does not undergo foaming expansion displacement.

[0004] The present invention is achieved through the following technical solutions: A composite material foaming forming control method comprises the following steps: S1: Place the lower die into the loading trolley and drive it into the body of the foam forming hydraulic press until it contacts the fixed pressure head; S2: The upper pressure head, the forward pressure head and the horizontal pressure heads on both sides are slidably mounted on the body of the foaming hydraulic press, the upper pressure head drives the upper mold downward, the forward pressure head moves backward, and the horizontal pressure heads on both sides move horizontally toward each other to reach the set position, and the forward pressure head locking device and the horizontal pressure head locking device on both sides respectively lock the forward pressure head and the horizontal pressure heads on both sides with the body of the foaming hydraulic press to complete the mold clamping; S3: The mold is heated to the set temperature and kept warm, and the composite material is injected into the mold and waited for foaming and forming; S4: During the foaming process, the locking force generated by the upper pressure head, the forward pressure head and the horizontal pressure heads on both sides adaptively matches the foaming force of the composite material to ensure that the mold does not undergo foaming and expansion displacement; S5: After the foaming is completed, the upper pressure head drives the upper mold upward, the forward pressure head locking device and the horizontal pressure head locking devices on both sides are opened, and the loading trolley drives the mold to exit the foaming hydraulic press body.

[0005] Optimized, in step S4, a virtual model is used for calculation to make the locking forces of the upper pressure head, the forward pressure head locking device and the horizontal pressure head locking devices on both sides adaptively match the foaming force of the composite material.

[0006] Furthermore, the virtual model in step S4 is formula (1): (1); in: Indicates the liquid pressure required to lock the cylinder. The injection rate of the composite material is The pressure exerted by the foaming force of the composite material on the corresponding pressure head is Indicates the viscosity of the liquid, Indicates the locking cylinder leakage coefficient, Indicates the radius of the locking cylinder. represents the composite material injection rate, Indicates the contact area between the indenter and the die. represents the coefficient of variation of the friction surface force, Indicates the sliding friction between the pressure head and the body of the hydraulic foaming press.

[0007] Furthermore, the virtual model is constructed using the following method: S41: Establish the foaming model as formula (2), and integrate the foaming model to obtain formula (3), and solve according to formula (3) Foaming power of composite materials : (2); (3); in: represents the initial foaming rate, represents the foaming decay constant; S42: According to Foaming power of composite materials Establishing the Foaming Force Distribution Function , and the foaming force distribution function Double integration is performed to obtain the positive pressure of the corresponding pressure head Formula (4): (4); in: is the coordinate of any point on the contact surface between the indenter and the die; S43: Calculate the sliding friction between the pressure head and the foam forming hydraulic press body according to formula (5): : (5); in: Indicates the sliding friction coefficient between the pressure head and the foam forming hydraulic press body; S44: Considering the influence of the change of friction surface force, according to the calculated sliding friction between the pressure head and the foam forming hydraulic press body The injection rate of the composite material is calculated as The pressure exerted by the foaming force of the composite material on the pressure head , construct a virtual model as formula (1) to calculate the liquid pressure required for locking the cylinder.

[0008] Optimized, the loading trolley is driven by a servo motor.

[0009] Optimally, the upper pressure head is synchronously driven by four upper pressure head driving cylinders distributed at four corners, and during the forming process, the upper pressure head driving cylinders provide a pressing force to adaptively match the foaming force of the composite material.

[0010] A composite material foaming hydraulic press, used to execute a composite material foaming control method described in any one of the above, comprising a foaming hydraulic press body, a loading trolley, a mold, an upper pressure head, a fixed pressure head, horizontal pressure heads on both sides, a forward pressure head, a heating unit and a programmable controller, wherein the horizontal pressure heads on both sides are slidably installed on both sides of the foaming hydraulic press body and are provided with horizontal pressure head locking devices on both sides, the forward pressure head is slidably installed on the front side of the foaming hydraulic press body and is provided with a forward pressure head locking device, the upper pressure head is slidably installed above the foaming hydraulic press body, the mold comprises an upper mold and a lower mold, the upper mold is driven up and down by the upper pressure head, the lower mold is installed on the loading trolley, the heating unit heats the mold temperature to a set temperature, the programmable controller is used to control the temperature of the heating unit, and calculate the locking force generated by the upper pressure head, the forward pressure head and the horizontal pressure heads on both sides during the foaming process to achieve adaptive matching of the composite material foaming force.

[0011] Furthermore, a composite material foaming hydraulic press, the heating unit includes heating blankets respectively installed on the upper mold, the forward pressing head, the horizontal pressing heads on both sides, the fixed pressing head and the upper surface of the loading trolley, the lower mold is provided with a temperature sensor to detect the lower mold temperature in real time and transmit the detection data to the programmable controller.

[0012] Furthermore, corresponding position sensors are installed on the loading trolley, lower die, upper pressure head, fixed pressure head, horizontal pressure heads on both sides, and forward pressure head, and the position sensors transmit the detected position information of the corresponding components to the programmable controller.

[0013] Furthermore, a multi-point upper die quick-change locking device is installed on the body of the foaming forming hydraulic press, and a locking block is installed on the upper die.

[0014] Beneficial effects of the invention: The present invention provides a composite material foaming forming hydraulic press and a forming control method, wherein mold feeding, control and locking of a pressure head, and locking forces generated by an upper pressure head, a forward pressure head, and horizontal pressure heads on both sides realize adaptive matching of the composite material foaming force, are all completed automatically by the equipment, with less human involvement and a relatively high degree of automation, thus saving manpower and improving production efficiency. Furthermore, in the foaming forming process, the locking forces generated by an upper pressure head, a forward pressure head, and horizontal pressure heads on both sides adaptively match the composite material foaming force, thus ensuring that the mold does not undergo foaming expansion displacement, thereby ensuring the product's external dimensions and surface quality. In addition, the machine has strong adaptability and can be applied to molds and products of different sizes. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a schematic diagram of the process of the present invention.

[0016] Figure 2 It is a schematic diagram of the three-dimensional structure of the system of the present invention.

[0017] Figure 3 It is a schematic diagram of the top view structure of the system of the present invention.

[0018] In the figure: 1. Body of the foam forming hydraulic press; 2. Loading trolley; 3. Forward pressing head locking device; 4. Forward pressing head; 5. Upper pressing head driving cylinder; 6. Horizontal pressing heads on both sides; 7. Horizontal pressing heads locking devices on both sides; 8. Fixed pressing head; 9. Upper pressing head; 10. Loading trolley locking device. DETAILED DESCRIPTION

[0019] A composite material foaming forming control method, the flow diagram of which is as follows Figure 1 As shown, the specific steps include: S1: Place the lower die into the loading trolley and drive it into the body of the foam forming hydraulic press until it contacts the fixed pressure head; The loading trolley includes two positions: a loading position and a working position. The loading trolley is used for loading and unloading the lower mold in the mold. When in the loading position, the lower mold can be placed on the loading trolley by a manipulator; then the loading trolley driving mechanism drives the loading trolley into the working position, and a loading trolley locking device 10 can be set in the body of the foam forming hydraulic press to position and lock the loading trolley; Specifically, the driving mechanism of the loading trolley can preferably be a servo motor.

[0020] S2: The upper pressure head, the forward pressure head and the horizontal pressure heads on both sides are slidably mounted on the body of the foaming hydraulic press, the upper pressure head drives the upper mold downward, the forward pressure head moves backward, and the horizontal pressure heads on both sides move horizontally toward each other to reach the set position, and the forward pressure head locking device and the horizontal pressure head locking device on both sides respectively lock the forward pressure head and the horizontal pressure heads on both sides with the body of the foaming hydraulic press to complete the mold clamping; Specifically, the upper pressure head can be synchronously driven by four upper pressure head driving cylinders 5 distributed at the four corners, and during the forming process, the upper pressure head driving cylinders provide a pressing force to adaptively match the foaming force of the composite material; the upper pressure head full-stroke dynamic four-corner position closed-loop control can be achieved, avoiding repeated positioning differences of the upper pressure head, which causes foaming and deformation.

[0021] The forward pressure head locking device can be driven by the forward pressure head locking cylinder to achieve locking, and the horizontal pressure head locking devices on both sides are driven by the horizontal pressure head locking cylinders on both sides to achieve locking.

[0022] Since the upper pressure head, forward pressure head and horizontal pressure heads on both sides of the foaming forming hydraulic press are arranged separately, and the upper pressure head, forward pressure head and horizontal pressure heads on both sides are slidably installed on the body of the foaming forming hydraulic press respectively, it has strong adaptability, can be applied to molds and products of different sizes, can realize automatic clamping, and has a relatively high degree of automation.

[0023] Specifically, guide rails can be set on the body of the foaming hydraulic press, and the upper pressure head, forward pressure head, and horizontal pressure heads on both sides can be slidably installed on the corresponding guide rails, and corresponding driving devices can drive them to reciprocate along the guide rails to ensure stable operation of the upper pressure head, forward pressure head, and horizontal pressure heads on both sides.

[0024] Specifically, the driving device of the horizontal pressure heads on both sides and the forward pressure head can adopt a worm gear structure driven by a servo motor, so that the operation of the horizontal pressure heads on both sides and the forward pressure head is more stable and reliable.

[0025] Furthermore, position sensors can be installed on the upper pressure head, the forward pressure head, and the horizontal pressure heads on both sides to detect position information of the upper pressure head, the forward pressure head, and the horizontal pressure heads on both sides, and transmit the position information to the programmable controller. The programmable controller determines whether the corresponding pressure head has reached the set position based on the preset position information, thereby controlling the start and stop of the corresponding pressure head driving device.

[0026] S3: After the mold is heated to the set temperature and kept warm, the composite material is injected into the mold and waited for foaming and forming; Specifically, a heating unit can be set to heat the mold to a set temperature and keep it warm. The composite material is kept stable within the set temperature range for foaming and forming, to prevent the foaming agent from rapidly cooling and solidifying when it is cold, resulting in uneven foaming density and foaming defects.

[0027] Optimally, the heating unit may include heating blankets respectively installed on the upper mold, the forward pressing head, the horizontal pressing heads on both sides, the fixed pressing head and the upper surface of the loading trolley. This can make the mold heated more evenly, which is more conducive to the foaming of the composite material in the mold and further prevents uneven foaming density and foaming defects.

[0028] S4: During the foaming process, the locking force generated by the upper pressure head, the forward pressure head and the horizontal pressure heads on both sides adaptively matches the foaming force of the composite material to ensure that the mold does not undergo foaming and expansion displacement; Optimally, the virtual model calculation method can be used to make the locking forces of the upper pressure head, the forward pressure head locking device and the horizontal pressure head locking devices on both sides adaptively match the foaming force of the composite material.

[0029] Specifically, the virtual model is formula (1): (1); in: Indicates the liquid pressure required to lock the cylinder. The injection rate of the composite material is The pressure exerted by the foaming force of the composite material on the corresponding pressure head is Indicates the viscosity of the liquid, Indicates the locking cylinder leakage coefficient, which can be obtained from the cylinder design parameters. Indicates the radius of the locking cylinder. represents the composite material injection rate, Indicates the contact area between the indenter and the die. represents the coefficient of variation of the friction surface force, is the injection pressure parameter value, which is related to the characteristics of the composite material. Its value can be directly obtained based on the composite material. Indicates the sliding friction between the pressure head and the body of the hydraulic foaming press.

[0030] Specifically, the construction method of the virtual model is as follows: S41: During the foaming process of the composite material, the foaming force changes with time. It grows linearly, but the growth rate gradually decreases. Therefore, the foaming model can be simulated by an exponential decay function. Therefore, the foaming model established is formula (2). The foaming model is integrated to obtain formula (3). According to formula (3), Foaming power of composite materials : (2); (3); in: represents the initial foaming rate, which is The foaming rate, represents the foaming decay constant; The value of The value of is related to the properties of the composite material itself. When the material and temperature are constant, The value of The value of is also determined, and its value can be obtained from the performance indicators of the composite material.

[0031] S42: Since the pressure distribution on the contact surface is non-uniform and varies in direct proportion to the foaming force, we need to consider the integral of the pressure over the entire contact surface. However, it is not common to integrate the friction directly, because the friction is usually proportional to the local normal pressure. Therefore, we can integrate the normal pressure and use this integral result to calculate the total friction.

[0032] according to Foaming power of composite materials Establishing the Foaming Force Distribution Function , and the foaming force distribution function Double integration is performed to obtain the positive pressure of the corresponding pressure head Formula (4): The foaming force distribution function established here That is, the coordinates on the contact surface are The foaming force at any point distribution, the total positive pressure N can be obtained by The double integral is performed on the points on the entire contact surface, so we have formula (4) (4); in: is the coordinate of any point on the contact surface between the indenter and the die; S43: Calculate the sliding friction between the pressure head and the foam forming hydraulic press body according to formula (5): : (5); in: It represents the sliding friction coefficient between the pressure head and the body of the foam forming hydraulic press. Its value is related to the material properties of the friction surface and can be directly found in the material property table.

[0033] S44: Considering the influence of the change of friction surface force, according to the calculated sliding friction between the pressure head and the foam forming hydraulic press body The injection rate of the composite material is calculated as The pressure exerted by the foaming force of the composite material on the pressure head , construct a virtual model as formula (1) to calculate the liquid pressure required for locking the cylinder.

[0034] During the foaming process, since the friction area is constant, the pressure changes with the change of the foaming force. When the two are equal, the mold remains relatively still. From then on, the constructed virtual model formula (1) is used to calculate the liquid pressure required for the locking cylinder, thereby changing the locking force of the corresponding pressure head, so that the generated locking force is adaptively matched to the foaming force of the composite material, which can ensure that the mold does not undergo foaming expansion displacement, thereby ensuring the product's appearance size and surface quality.

[0035] In addition, the virtual model constructed as formula (1) takes into account the influence of injection pressure parameters and the design parameters of the cylinder itself, and the calculation results are relatively accurate and reliable.

[0036] S5: After the foaming is completed, the upper pressure head drives the upper mold upward, the forward pressure head locking device and the horizontal pressure head locking devices on both sides are opened, and the loading trolley drives the mold to withdraw from the foaming hydraulic press body, thereby completing the foaming of the composite material. The shape size and surface quality of the product after foaming can meet the design requirements.

[0037] A composite material foaming hydraulic press, such as Figure 2 , Figure 3 As shown, a composite material foaming forming control method for executing any one of the above-mentioned items includes a foaming forming hydraulic press body 1, a loading trolley 2, a mold, an upper pressure head 9, a fixed pressure head 8, horizontal pressure heads on both sides 6, a forward pressure head 4, a heating unit and a programmable controller. The horizontal pressure heads on both sides are slidably installed on both sides of the foaming forming hydraulic press body and are provided with horizontal pressure head locking devices 7 on both sides. The forward pressure head is slidably installed on the front side of the foaming forming hydraulic press body and is provided with a forward pressure head locking device 3. The upper pressure head is slidably installed above the foaming forming hydraulic press body. The mold includes an upper mold and a lower mold. The upper mold is driven up and down by the upper pressure head. The lower mold is installed on the loading trolley. The heating unit heats the mold temperature to a set temperature. The programmable controller is used to control the temperature of the heating unit, and calculates the locking force generated by the upper pressure head, the forward pressure head and the horizontal pressure heads on both sides during the waiting process of foaming forming to achieve adaptive matching of the composite material foaming force.

[0038] Furthermore, a composite material foaming hydraulic press, the heating unit includes heating blankets respectively installed on the upper mold, the forward pressing head, the horizontal pressing heads on both sides, the fixed pressing head and the upper surface of the loading trolley, the lower mold is provided with a temperature sensor to detect the lower mold temperature in real time and transmit the detection data to the programmable controller.

[0039] Furthermore, corresponding position sensors are installed on the loading trolley, lower die, upper pressure head, fixed pressure head, horizontal pressure heads on both sides, and forward pressure head, and the position sensors transmit the detected position information of the corresponding components to the programmable controller.

[0040] Furthermore, a multi-point upper mold quick-change locking device is installed on the body of the foaming molding hydraulic press, and a locking block is installed on the upper mold, which can perform multi-point locking on the upper mold to meet the needs of different molds and product sizes.

[0041] In summary, the composite material foaming hydraulic press and forming control method provided by the present invention have less manpower participation and a relatively high degree of automation, which saves manpower and improves production efficiency. In addition, during the process of waiting for foaming, the locking force generated by the upper pressure head, the forward pressure head and the horizontal pressure heads on both sides adaptively matches the foaming force of the composite material, which can ensure that the mold does not undergo foaming and expansion displacement, thereby ensuring the product's external dimensions and surface quality. It also has strong adaptability and can be suitable for molds and products of different sizes.

[0042] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A composite material foaming forming control method, characterized in that: The steps include: S1: Place the lower die into the loading trolley and drive it into the body of the foam forming hydraulic press until it contacts the fixed pressure head; S2: The upper pressure head, the forward pressure head and the horizontal pressure heads on both sides are slidably mounted on the body of the foaming hydraulic press, the upper pressure head drives the upper mold downward, the forward pressure head moves backward, and the horizontal pressure heads on both sides move horizontally toward each other to reach the set position, and the forward pressure head locking device and the horizontal pressure head locking device on both sides respectively lock the forward pressure head and the horizontal pressure heads on both sides with the body of the foaming hydraulic press to complete the mold clamping; S3: After the mold is heated to the set temperature and kept warm, the composite material is injected into the mold and waited for foaming and forming; S4: During the foaming process, the locking force generated by the upper pressure head, the forward pressure head and the horizontal pressure heads on both sides adaptively matches the foaming force of the composite material to ensure that the mold does not undergo foaming and expansion displacement; S5: After the foaming is completed, the upper pressure head drives the upper mold upward, the forward pressure head locking device and the horizontal pressure head locking devices on both sides are opened, and the loading trolley drives the mold to exit the foaming hydraulic press body.

2. A composite material foaming forming control method according to claim 1, characterized in that: In step S4, a virtual model is used to calculate so that the locking forces of the upper pressure head, the forward pressure head locking device and the horizontal pressure head locking devices on both sides are adaptively matched to the foaming force of the composite material.

3. A composite material foaming forming control method according to claim 2, characterized in that: The virtual model in step S4 is formula (1): （1）； in: Indicates the liquid pressure required to lock the cylinder. The injection rate of the composite material is The pressure exerted by the foaming force of the composite material on the corresponding pressure head is Indicates the viscosity of the liquid, Indicates the locking cylinder leakage coefficient, Indicates the radius of the locking cylinder. represents the composite material injection rate, Indicates the contact area between the indenter and the die. represents the coefficient of variation of the friction surface force, Indicates the sliding friction between the pressure head and the body of the hydraulic foaming press.

4. A composite material foaming forming control method according to claim 3, characterized in that: The virtual model is constructed using the following method: S41: Establish the foaming model as formula (2), and integrate the foaming model to obtain formula (3), and solve according to formula (3) Foaming power of composite materials : （2）； （3）； in: represents the initial foaming rate, represents the foaming decay constant; S42: According to Foaming power of composite materials Establishing the Foaming Force Distribution Function , and the foaming force distribution function Double integration is performed to obtain the positive pressure of the corresponding pressure head Formula (4): （4）； in: is the coordinate of any point on the contact surface between the indenter and the die; S43: Calculate the sliding friction between the pressure head and the foam forming hydraulic press body according to formula (5): : （5）； in: Indicates the sliding friction coefficient between the pressure head and the foam forming hydraulic press body; S44: Considering the influence of the change of friction surface force, according to the calculated sliding friction between the pressure head and the foam forming hydraulic press body The injection rate of the composite material is calculated as The pressure exerted by the foaming force of the composite material on the pressure head , construct a virtual model as formula (1) to calculate the liquid pressure required for locking the cylinder.

5. A composite material foaming forming control method according to claim 1, characterized in that: The loading trolley is driven by a servo motor.

6. A composite material foaming forming control method according to claim 1, characterized in that: The upper pressure head is synchronously driven by four upper pressure head driving cylinders distributed at four corners, and during the forming process, the upper pressure head driving cylinders provide a pressing force to adaptively match the foaming force of the composite material.

7. A composite foaming hydraulic press, used to execute a composite foaming control method as claimed in any one of claims 1 to 6, characterized in that: It includes a foaming hydraulic press body, a loading trolley, a mold, an upper pressure head, a fixed pressure head, horizontal pressure heads on both sides, a forward pressure head, a heating unit and a programmable controller. The horizontal pressure heads on both sides are slidably installed on both sides of the foaming hydraulic press body and are provided with horizontal pressure head locking devices on both sides. The forward pressure head is slidably installed on the front side of the foaming hydraulic press body and is provided with a forward pressure head locking device. The upper pressure head is slidably installed above the foaming hydraulic press body. The mold includes an upper mold and a lower mold. The upper mold is driven up and down by the upper pressure head. The lower mold is installed on the loading trolley. The heating unit heats the mold temperature to a set temperature. The programmable controller is used to control the temperature of the heating unit and calculate the locking force generated by the upper pressure head, the forward pressure head and the horizontal pressure heads on both sides during the foaming process to achieve adaptive matching of the foaming force of the composite material.

8. A composite material foaming hydraulic press according to claim 7, characterized in that: The heating unit includes heating blankets respectively installed on the upper mold, the forward pressing head, the horizontal pressing heads on both sides, the fixed pressing head and the upper surface of the loading trolley. The lower mold is provided with a temperature sensor to detect the lower mold temperature in real time and transmit the detection data to the programmable controller.

9. A composite material foaming hydraulic press according to claim 7, characterized in that: The loading trolley, the lower die, the upper pressure head, the fixed pressure head, the horizontal pressure heads on both sides, and the forward pressure head are all equipped with corresponding position sensors, and the position sensors transmit the detected position information of the corresponding components to the programmable controller.

10. A composite material foaming hydraulic press according to claim 7, characterized in that: A multi-point upper die quick-change locking device is installed on the body of the foam forming hydraulic press, and a locking block is installed on the upper die.

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