A method and system for compression molding a product based on thermoplastic carbon fiber composites

Abstract

The present application relates to thermoplastic carbon fiber composite material injection technology field, especially to a kind of product injection method and system based on thermoplastic carbon fiber composite material, its method includes the following steps: installing ejector rod on press ejector rod platform;When upper die reaches the set upper die slow down position but has not contacted ejector rod after thermoplastic carbon fiber composite material is injected into mold, programmable controller is fitted to upper die position curve and ejector rod position curve, make two curves consistent;When upper die contacts ejector rod, programmable controller controls proportional overflow valve in real time according to the pressure of hydraulic cylinder, so that the pressure of ejector rod and the pressure of upper die match, realize initial rapid mold closing to ensure that the resistance of ejector rod reaches minimum and does not separate from upper die.The method and system provided by the present application solve the problem that traditional process cannot form reserved hole at one time, without fiber cutting, the strength and appearance quality are relatively good, and the process is reduced, and the efficiency is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of hot plastic carbon fiber composite material injection molding, in particular to a product injection molding method and system based on hot plastic carbon fiber composite material. BACKGROUND

[0002] With the rise of domestic new energy vehicles, the lightweight of automobile parts is continuously improved, and the use of new materials instead of traditional metal materials can achieve lighter weight while achieving better performance. It brings better endurance to the car, provides better handling, and also brings better choices to rail transit and aerospace.

[0003] The hot plastic composite material injection molding process is to put the raw materials into the mold, and the raw materials in the mold are completed by the press. The shaped product often has a post-opening hole in the position, which can be pressed by a subsequent press or can be pre-reserved in a thin position. Post-grinding. But no matter which kind of opening, it will make the fiber break, resulting in a decrease in strength. At the same time, this traditional process will cause the entire production line to be unable to be formed at one time, and needs to be processed twice or three times. And due to the hot plastic molding process, it needs to be quickly molded and pressed, and the traditional ejector rod cannot be tightly attached to the mold during the quick molding process, resulting in no way to form a pre-reserved hole at one time.

[0004] Hot plastic carbon fiber is a better base material than glass fiber in performance, and its addition will make the mechanical properties of the shaped product better, but it will cause difficulty in subsequent opening and reduce efficiency. SUMMARY

[0005] The technical problem to be solved by the present application is to provide a product injection molding method and system based on hot plastic carbon fiber composite material, which solves the problem of traditional process that cannot form a pre-reserved hole at one time, without fiber cutting, good strength and appearance quality, and reduces the process and improves the efficiency.

[0006] The present application is realized by the following technical solutions:

[0007] A product injection molding method based on hot plastic carbon fiber composite material, comprising the following steps:

[0008] S1: The top rod platform of the press is provided with a top rod penetrating through the lower mold reserved hole at a position corresponding to the product opening hole position of the lower mold;

[0009] S2: After the thermoplastic carbon fiber composite material is injected into the mold, the press closes the mold. When the upper mold reaches the set upper mold slow-down position but has not yet contacted the ejector pin, the programmable controller uses mathematical fitting method to obtain the upper mold position curve and the ejector pin position curve, and fits the upper mold position curve and the ejector pin position curve to make the two curves tend to be consistent, so that when the upper mold approaches the ejector pin, the ejector pin moves down in advance and moves together with the upper mold.

[0010] S3: When the upper mold contacts the ejector pin, the programmable controller opens the ejector pin retraction switch valve. The upper mold presses the ejector pin to move passively downward. The hydraulic oil in the ejector pin cylinder is compressed to generate pressure. The programmable controller controls the proportional relief valve in real time according to the pressure of the hydraulic cylinder to match the pressure of the ejector pin with the pressure of the upper mold. This ensures that the ejector pin resistance is minimized and does not detach from the upper mold during the initial rapid mold closing.

[0011] Furthermore, in step S2, the upper mold position curve is given by equation (1), the ejector pin position curve is given by equation (2), and the fitting curve of the upper mold position curve and the ejector pin position curve is given by equation (3):

[0012] (1);

[0013] (2);

[0014] (3);

[0015] in: express The position of the upper mold at any time. This represents the quadratic fitting coefficient of the upper mold position curve. This represents the fitting coefficient of the first-order term of the upper mold position curve. This represents the fitting coefficient of the constant term of the upper mold position curve. express The position of the push rod at all times. This represents the quadratic fitting coefficient of the pushrod position curve. This represents the fitting coefficient of the first-order term of the push rod position curve. This represents the fitting coefficient of the constant term of the push rod position curve.

[0016] Furthermore, in step S2, when the upper die reaches the set lowering position but has not yet contacted the ejector pin, the downward speed of the upper die increases to the set downward speed, and the downward speed of the ejector pin is calculated according to equation (4), so that the ejector pin descends ahead of time according to the calculated downward speed:

[0017] (4);

[0018] in: Indicates the downward speed of the push rod. Indicates the damping factor. This indicates the downward speed of the upper mold.

[0019] In the optimized version, step S2 uses an upper mold position sensor to sense the upper mold position and transmits the sensed upper mold position information to the programmable controller. Similarly, an ejector pin position sensor senses the ejector pin position and transmits the sensed ejector pin position information to the programmable controller.

[0020] In the optimized step S3, the programmable controller uses a modeless adaptive control algorithm model to control the pressure of the push rod to match the pressure of the upper mold.

[0021] Furthermore, the model of the modeless adaptive control algorithm is given by equation (5):

[0022] (5);

[0023] in: express The estimated value of the pseudo-partial derivative at time step 1. express The estimated value of the pseudo-partial derivative at time step 1. Representing a time series, Indicates the positive weighting coefficient. express Change in pressure of the upper mold at any given time express Change in pressure on the push rod at any given time. express Constant pressure on the mold, express Constant pressure on the mold, Represents the step size sequence. express Constant pressure control deviation of the push rod.

[0024] Furthermore, a product injection method based on thermoplastic carbon fiber composite material also includes step S4: when the mold is fully closed, the upper mold pressure reaches the set pressure threshold and enters the pressure holding state. If the ejection and passive retraction pressure of the mold ejector cylinder decreases to the set threshold, the forward interface of the proportional directional valve opens, and the proportional pressure reducing valve adjusts the output value of the proportional pressure reducing valve according to formula (6) to achieve pressure compensation.

[0025] (6);

[0026] in: express The control output value of the proportional pressure reducing valve at any given time. This represents the proportional adjustment coefficient. This represents the integral adjustment coefficient. express A difference between a target pressure of the proportional pressure reducing valve and a real-time pressure, The differential adjustment coefficient is represented.

[0027] Further, the product compression injection method based on thermoplastic carbon fiber composite material further comprises the step S5: pressure maintaining is ended, the upper die is demoulded and returned, the workpiece is pressed and formed, the proportional control valve is controlled by the programmable controller to open the reverse interface, the output pressure of the proportional pressure reducing valve is controlled, the ejector rod is returned under the constant pressure and flow, and the product is formed with a reserved hole in the returning position.

[0028] The product compression injection system based on thermoplastic carbon fiber composite material is used for executing the product compression injection method based on thermoplastic carbon fiber composite material, and comprises a mold unit, a programmable controller and an auxiliary hydraulic control unit. The auxiliary hydraulic control unit comprises an active return oil circuit of the ejector rod oil cylinder connected with the ejector rod oil cylinder and an ejecting and passive return oil circuit of the ejector rod oil cylinder. The active return oil circuit of the ejector rod oil cylinder is provided with an active return oil circuit pressure sensor of the ejector rod oil cylinder, a proportional directional valve and a proportional pressure reducing valve. The ejecting and passive return oil circuit of the ejector rod oil cylinder is provided with an ejecting and passive return oil circuit pressure sensor of the ejector rod oil cylinder, a passive return switch valve of the ejector rod and a proportional overflow valve. The active return oil circuit pressure sensor of the ejector rod oil cylinder is used for detecting pressure data of the active return oil circuit of the ejector rod oil cylinder and transmitting the pressure data to the programmable controller. The ejecting and passive return oil circuit pressure sensor of the ejector rod oil cylinder is used for detecting pressure data of the ejecting and passive return oil circuit of the ejector rod oil cylinder and transmitting the pressure data to the programmable controller. The programmable controller is used for controlling the output of the proportional pressure reducing valve, the reversing of the proportional directional valve, the opening and closing of the passive return switch valve of the ejector rod and the output of the proportional overflow valve.

[0029] The application has the following beneficial effects:

[0030] The product compression injection method and system based on thermoplastic carbon fiber composite material provided by the application solve the problem that the traditional process cannot form a reserved hole at one time. In the production process, before feeding, the programmable controller sends an instruction to the auxiliary hydraulic control unit to make the mold ejector rod eject. When the upper die reaches the set slow lower position but has not contacted the ejector rod, the programmable controller obtains the upper die position curve and the ejector rod position curve by using a mathematical fitting method, fits the upper die position curve and the ejector rod position curve, and makes the two curves consistent, so that the ejector rod can descend in advance when the upper die approaches the ejector rod, and the high-speed mold closing process can be avoided.

[0031] When the upper die contacts the ejector rod, the programmable controller opens the ejector rod retreat switch valve, the upper die presses the ejector rod to move downward passively, the hydraulic oil of the ejector rod oil cylinder is compressed to generate pressure, the programmable controller controls the proportional overflow valve in real time according to the pressure of the hydraulic oil cylinder, so that the pressure of the ejector rod matches the pressure of the upper die, the resistance of the ejector rod is ensured to be minimum and not to be separated from the upper die during initial rapid mold closing, so that the injection quality of the reserved hole is ensured, and the injection cost is well controlled.

[0032] When the pressing is completed, the ejector rod retreats, at this time the workpiece has been solidified and the ejector rod retreats part has an opening. The whole injection process is one-time forming, without secondary processing, reducing the process, improving the efficiency, and the reserved hole has no fiber cutting due to one-time forming, and the product strength and appearance quality are better. BRIEF DESCRIPTION OF DRAWINGS

[0033] Figure 1 It is a flowchart of the present application.

[0034] Figure 2 It is a schematic diagram of the mold unit structure of the present application.

[0035] Figure 3 It is a schematic diagram of the auxiliary hydraulic control unit structure of the present application.

[0036] In the figure: 1, upper die; 2, ejector rod; 3, lower die; 4, ejector rod platform; 5, ejector rod oil cylinder; 6, ejector rod oil cylinder retreat oil port; 7, ejector rod oil cylinder ejection oil port; 8, ejector rod oil cylinder active retreat oil path pressure sensor; 9, ejector rod oil cylinder active retreat oil path pressure sensor; 10, proportional pressure reducing valve; 11, proportional overflow valve; 12, ejector rod passive retreat switch valve; 13, ejector rod oil cylinder ejection and passive retreat oil path pressure sensor. DETAILED DESCRIPTION

[0037] A product injection method based on thermoplastic carbon fiber composite material, the flowchart is as shown in Figure 1 The specific steps include the following steps:

[0038] S1: The ejector rod which passes through the lower die reserved hole is installed on the press ejector rod platform at the position corresponding to the product opening position of the lower die;

[0039] S2: After the thermoplastic carbon fiber composite material is injected into the mold, the press is closed, when the upper die reaches the set upper die slow down position but has not contacted the ejector rod, the programmable controller obtains the upper die position curve and the ejector rod position curve by using mathematical fitting method, and fits the upper die position curve and the ejector rod position curve, so that the two curves are consistent, and the ejector rod is lowered in advance to follow the upper die when the upper die approaches the ejector rod;

[0040] Specifically, an upper mold position sensor can be used to sense the position of the upper mold, and the upper mold position sensor can transmit the sensed upper mold position information to the programmable controller. Similarly, an ejector pin position sensor can be used to sense the position of the ejector pin, and the ejector pin position sensor can transmit the sensed ejector pin position information to the programmable controller.

[0041] Specifically, the industrial control computer can be used to set system parameters such as the mold closing position of the thermoplastic carbon fiber composite material press, the ejection and retraction speed and pressure of the auxiliary hydraulic control system, and transmit the set parameters to the programmable controller.

[0042] Furthermore, the upper mold position curve is given by equation (1), the ejector pin position curve is given by equation (2), and the fitting curve of the upper mold position curve and the ejector pin position curve is given by equation (3):

[0043] (1);

[0044] (2);

[0045] (3);

[0046] in: express The position of the upper mold at all times. This represents the quadratic fitting coefficient of the upper mold position curve. This represents the fitting coefficient of the first-order term of the upper mold position curve. This represents the fitting coefficient of the constant term of the upper mold position curve. express The position of the push rod at all times. This represents the quadratic fitting coefficient of the pushrod position curve. This represents the fitting coefficient of the first-order term of the pushrod position curve. This represents the fitting coefficient of the constant term of the push rod position curve.

[0047] , , , , , The least squares method can be used to fit a quadratic function equation in one variable to determine the result.

[0048] When the upper die reaches the set lowering position but has not yet contacted the ejector pin, the upper die position curve and the ejector pin position curve are fitted by fitting the upper die position curve and the ejector pin position curve (3). This can make the upper die position curve and the ejector pin position curve more consistent, so that when the upper die approaches the ejector pin, the ejector pin moves down in advance and moves together with the upper die, which can reduce the impact force when the upper die contacts the ejector pin.

[0049] Further, when the upper die reaches the set upper die slow down position but has not contacted the ejector rod, the upper die descending speed is accelerated to the set descending speed, and the ejector rod descending speed is calculated according to formula (4), so that the ejector rod descends in advance according to the calculated ejector rod descending speed:

[0050] (4);

[0051] Wherein: represents the ejector rod descending speed, represents the impact reduction coefficient, represents the upper die descending speed.

[0052] When the upper die reaches the set upper die slow down position but has not contacted the ejector rod, the upper die descending speed is accelerated to the set descending speed, and the ejector rod descending speed is controlled according to formula (4), not only the impact force at the time of contact is reduced, but also the rapid die closing can be realized, which is more in line with the characteristics of thermoplastic carbon fiber composite materials and is beneficial to product quality.

[0053] S3: When the upper die contacts the ejector rod, the programmable controller opens the ejector rod return on-off valve, the upper die presses the ejector rod to move downward passively, the hydraulic oil of the ejector rod oil cylinder is compressed to generate pressure, and the programmable controller controls the proportional overflow valve in real time according to the pressure of the hydraulic oil cylinder, so that the pressure of the ejector rod matches the pressure of the upper die, and the minimum resistance of the ejector rod is ensured when the initial rapid die closing is realized.

[0054] Since the thermoplastic carbon fiber composite material will crystallize quickly, it needs to be filled more quickly, and since the upper die needs to press the ejector rod to run downward during die closing, the ejector rod will provide a counterforce to the upper die, which will slow down the die closing. In order to solve this problem, when the upper die contacts the ejector rod, the programmable controller opens the ejector rod return on-off valve, the hydraulic oil of the ejector rod oil cylinder is compressed to generate pressure, and the programmable controller controls the proportional overflow valve in real time according to the pressure of the hydraulic oil cylinder, so that the pressure of the ejector rod matches the pressure of the upper die, and the minimum resistance of the ejector rod is ensured when the initial rapid die closing is realized.

[0055] Specifically, the programmable controller can use a model-free adaptive control algorithm to control the pressure of the ejector rod to match the pressure of the upper die.

[0056] Specifically, the model-free adaptive control algorithm is formula (5):

[0057] (5);

[0058] Wherein: represents the estimate value of the pseudo partial derivative at the moment t, represents the estimate value of the pseudo partial derivative at the moment t, represents the estimate value of the pseudo partial derivative at the moment t, represents the estimate value of the pseudo partial derivative at the moment t, represents a time sequence, represents a positive weight coefficient, represents an upper die pressure change amount at a time, represents a ejector rod pressure change amount at a time, represents an upper die pressure at a time, represents an upper die pressure at a time, represents a step sequence, represents a ejector rod pressure control deviation at a time.

[0059] Since a general discrete-time nonlinear system can be represented as formula (7):

[0060] (7);

[0061] wherein: represents a ejector rod actual pressure at a time, represents a ejector rod actual pressure at a time, represents a ejector rod actual pressure at a time, represents a ejector rod actual pressure at a time, represents a nonlinear function, represents an upper die pressure at a time, represents an upper die pressure at a time, represents an upper die pressure at a time, represents an output order of the ejector rod actual pressure, represents an output order of the upper die pressure, , is a positive integer.

[0062] Since the present application only needs to perform adaptive control on the ejector rod pressure relative to the upper die pressure, the ejector rod pressure control is a single-input single-output system, a tight format non-mode adaptive control on a one-dimensional nonlinear discrete-time system is established, and the input and output of the control system are observable and controllable.

[0063] the partial derivative of the system input, i.e. an upper die pressure at a time is continuous, and satisfies the generalized Lipschitz continuous condition, for any time and , formula (8) is established:

[0064] (8);

[0065] in: express The actual pressure of the push rod relative to the moment The change in actual pressure on the push rod at any given moment. This represents a proportionality constant, the actual value of which can be obtained from molding experiments, and is preferably 1.2. express The pressure of the upper mold relative to the time The change in pressure of the upper mold at any given time. This indicates taking the absolute value.

[0066] Because it satisfies Input to the system Pressure of the upper mold at all times The partial derivatives of are continuous and satisfy the generalized Lipschitz continuity condition for any time. and Then when At that time, it must exist. Pseudo-partial derivatives at time Make equation (9) true:

[0067] (9);

[0068] From equation (8), we can obtain the linearization model based on the compact scheme as equation (10):

[0069] (10);

[0070] Here Time-wise pseudo-partial derivatives It is a time variable, related to the pressure value of the push rod at the current moment. Therefore, the tight-format linearization model described by equation (10) transforms the nonlinear system into a linearized system with a time variable in a very simple way. In order to make the tight-format linearization model described by equation (10) reasonable, it is necessary to control the change of the input of the tight-format linearization model.

[0071] For general discrete-time systems, the control algorithm obtained by minimizing the one-step forward prediction error criterion function may encounter situations where the input is too large, leading to system corruption. Conversely, the control algorithm obtained by the minimum weighted one-step forward prediction error criterion function may generate steady-state tracking errors. For the nonlinear system described by equation (7), excessively large input changes indicate… Time-wise pseudo-partial derivatives The value may be too large, resulting in the inability to generate steady-state tracking error. Therefore, the form of the control input criterion function is set as equation (11):

[0072] (11);

[0073] wherein: represents the upper die pressure at time , the estimated criterion function, represents the control deviation, , represents the ejector rod target pressure, the value of which is equal to the upper die pressure, represents the weight coefficient, which can be set according to actual conditions.

[0074] According to minimizing , formula (12) can be obtained:

[0075] (12);

[0076] wherein: represents the step sequence, the specific value of which can be set according to actual conditions.

[0077] Since the pseudo partial derivative at time is unknown, the online estimation value of the pseudo partial derivative at time is used to replace to perform calculation, and formula (12) is converted into the online dynamic linearization model as formula (13):

[0078] (13);

[0079] In order to prevent the estimation value of the pseudo partial derivative at time from changing too fast, the estimated criterion function of the pseudo partial derivative at time is set as formula (14):

[0080] (14);

[0081] wherein: represents the online estimation value of the pseudo partial derivative at time .

[0082] According to formula (13), the minimization method is used to minimize , and the estimation model of the pseudo partial derivative is formula (15):

[0083] (15);

[0084] wherein: represents the time sequence, represents ​​Online estimation of instantaneous pseudo-derivative .

[0085] The moldless adaptive control algorithm model is obtained by combining formula (15) and formula (13) as formula (5).

[0086] Through the above moldless adaptive control algorithm model, the ejector rod pressure can always follow the change of the upper die pressure, and this algorithm has its adaptive characteristics, which can better complete the curve matching, ensure the carbon fiber thermoplastic process, and complete the self-matching of the ejector rod. With the closing of the mold, the upper die pressure rises, and the ejector rod can always passively retreat downward with the matching force of the upper die. When the mold contacts the raw material, an opposite resistance will be formed immediately. If the ejector rod does not have an initial passive pressure, it will continue to move downward due to inertia. Finally, it will cause a gap between the ejector rod and the upper die, which cannot achieve the purpose of reserving the hole. After the mold contacts the raw material, due to the need for rapid mold closing of thermoplastic materials, and due to the characteristics of continuous fibers used in carbon fiber, the pressing speed of the upper die will be very fast, and the mold will continue to close downward, causing the raw material in the mold to be quickly filled, and the ejector rod to passively retreat quickly with the matching pressure. The ejector rod is always in close contact with the upper die of the mold, ensuring the formation of the reserved hole. In order to ensure performance, a large-diameter proportional overflow valve can be used to achieve the purpose of rapid oil discharge, ensuring that the oil discharge flow is greater than 100L / min, thereby solving the problem of one-time forming of the reserved hole in the product injection molding of thermoplastic carbon fiber composites. The entire injection molding process is one-time forming, without the need for secondary processing, reducing the process, improving efficiency, and the reserved hole has no fiber cutting due to one-time forming, and the product strength and appearance quality are good.

[0087] Further, a product injection molding method based on thermoplastic carbon fiber composites further comprises step S4: when the mold is fully closed, the upper die pressure reaches the set pressure threshold to enter the pressure holding state, and if the mold ejector rod oil cylinder is ejected and the passive retreat pressure is reduced to the set threshold, the proportional directional valve positive interface is opened, the proportional pressure reducing valve adjusts the proportional pressure reducing valve output value according to formula (6), and the pressure compensation is realized:

[0088] (6);

[0089] Wherein: represents the control output value of the proportional pressure reducing valve at the moment, represents the proportional adjustment coefficient, represents the integral adjustment coefficient, represents the difference between the target pressure and the real-time pressure of the proportional pressure reducing valve at the moment, represents the differential adjustment coefficient.

[0090] Here, , 、 The simulation can be performed by a simulation model, and the order of magnitude of each coefficient is determined first, then the integral and differential are not added, the proportion is adjusted to just oscillate, then it is adjusted a little smaller, the integral is added, the steady-state error is adjusted, and finally the differential is added for adjustment, so as to calculate the best 、 、 .

[0091] By adjusting the proportional adjustment coefficient, the integral adjustment coefficient and the differential adjustment coefficient, real-time control of the active ejection pressure can be realized, and the feedback of the corresponding pressure sensor is matched, so that the pressure can be quickly and accurately closed-loop supplemented. After the pressure maintaining is completed, the mold is demolded and returned, and the upper and lower molds are separated.

[0092] Further, a product compression injection method based on thermoplastic carbon fiber composite material further comprises the following steps: S5: after the pressure maintaining is completed, the mold is demolded and returned, the workpiece is pressed and formed, the programmable controller controls the reverse interface of the proportional directional valve to be opened, controls the output pressure of the proportional pressure reducing valve, and makes the ejector rod complete the return action under constant pressure and flow. The product forms a reserved hole at the return position.

[0093] After the workpiece is pressed and formed, the programmable controller controls the reverse interface of the proportional directional valve to be opened, controls the output pressure of the proportional pressure reducing valve, and makes the ejector rod complete the return action under constant pressure and flow. In cooperation with the corresponding pressure sensor, a pressure closed-loop adjustment can be formed, and the ejector rod can output hydraulic pressure at a constant pressure and flow during the return process.

[0094] When the ejector rod is completely returned, the whole process is completed, and the product is taken out to leave a reserved hole which is once formed and has good quality.

[0095] A product compression injection system based on thermoplastic carbon fiber composite material is used to execute the product compression injection method based on thermoplastic carbon fiber composite material described in any one of the above, and comprises a mold unit, a programmable controller and an auxiliary hydraulic control unit.

[0096] The mold unit includes an upper mold 1, a lower mold 3, an ejector platform 4, an ejector 2, and an ejector cylinder 5. The ejector is mounted on the ejector platform and passes through a pre-drilled hole in the lower mold. The ejector cylinder is mounted on the lower mold and drives the ejector platform to move up and down. The auxiliary hydraulic control unit includes an active retraction oil circuit and an ejector extension and passive retraction oil circuit connected to the ejector cylinder. The active retraction oil circuit is equipped with an active retraction oil circuit pressure sensor 8, a proportional directional valve 9, and a proportional pressure reducing valve 10. The ejector extension and passive retraction oil circuit is equipped with ejector extension and passive retraction oil circuits. The system includes a retraction oil circuit pressure sensor 13, a push rod passive retraction switch valve 12, and a proportional relief valve 11. The push rod cylinder active retraction oil circuit pressure sensor is used to detect the pressure data of the push rod cylinder active retraction oil circuit and transmit the pressure data to the programmable controller. The push rod cylinder ejection and passive retraction oil circuit pressure sensors are used to detect the pressure data of the push rod cylinder ejection and passive retraction oil circuits and transmit the pressure data to the programmable controller. The programmable controller is used to control the output of the proportional pressure reducing valve, the switching of the proportional directional valve, the opening and closing of the push rod passive retraction switch valve, and the output of the proportional relief valve.

[0097] The schematic diagram of the mold unit structure is as follows: Figure 2 As shown in the diagram, the auxiliary hydraulic control unit structure is as follows: Figure 3 As shown, Figure 2 The push rod cylinder push outlet 7 and Figure 3 Port B is connected. When oil is supplied through port B, the ejector cylinder moves upward, and the ejector rod is pushed out. At the same time, when the upper mold contacts the ejector rod, oil is also discharged through port B. Figure 2 The push rod cylinder retraction port 6 and Figure 3 When port A is connected, and oil is supplied through port A, the push rod cylinder moves downward and the push rod retracts.

[0098] In summary, the product injection molding method and system based on thermoplastic carbon fiber composite material provided by this invention solves the problem that traditional processes cannot form pre-reserved holes in one step. When the upper mold approaches the ejector pin, the ejector pin moves downward in advance and moves together with the upper mold, which can avoid the impact of the ejector pin during the high-speed mold closing process and avoid defects in the workpiece. When the upper mold contacts the ejector pin, the pressure of the ejector pin matches the pressure of the upper mold, ensuring that the ejector pin resistance is minimized and does not detach from the upper mold during the initial rapid mold closing. This ensures both the injection molding quality of the pre-reserved hole and the control of injection molding costs. After the molding is completed, the ejector pin retracts. The entire injection molding process is formed in one step without secondary processing, reducing the number of steps and improving efficiency. Furthermore, since the pre-reserved hole is formed in one step without fiber cutting, the product strength and appearance quality are better.

[0099] The above merely provides the preferred embodiments of the present application, and is not used to limit the present application. For those skilled in the art, the present application can have various modifications and changes. Any modifications, equivalent replacements, improvements, etc. made within the principles and technical scope of the present application shall fall into the scope of the present application.

Claims

1. A product injection molding method based on thermoplastic carbon fiber composite material, characterized in that: Includes the following steps: S1: The press ejector platform is equipped with ejector rods that pass through the pre-drilled holes in the lower mold at positions corresponding to the opening positions of the lower mold products; S2: After the thermoplastic carbon fiber composite material is injected into the mold, the press closes the mold. When the upper mold reaches the set upper mold slow-down position but has not yet contacted the ejector pin, the programmable controller uses mathematical fitting method to obtain the upper mold position curve and the ejector pin position curve, and fits the upper mold position curve and the ejector pin position curve to make the two curves tend to be consistent, so that when the upper mold approaches the ejector pin, the ejector pin moves down in advance and moves together with the upper mold. S3: When the upper mold contacts the ejector pin, the programmable controller opens the ejector pin retraction switch valve, the upper mold presses the ejector pin to move passively downward, the hydraulic oil in the ejector pin cylinder is compressed to generate pressure, the programmable controller controls the proportional relief valve in real time according to the pressure of the hydraulic cylinder, and uses a moldless adaptive control algorithm model to control the pressure of the ejector pin to match the pressure of the upper mold, so as to ensure that the ejector pin resistance is minimized and does not detach from the upper mold during the initial rapid mold closing. The model of the modeless adaptive control algorithm is Equation (5): （5）； in: express The estimated value of the pseudo-partial derivative at time step 1. express The estimated value of the pseudo-partial derivative at time step 1. Representing a time series, Indicates the positive weighting coefficient. express Change in pressure of the upper mold at any given time express Change in pressure on the push rod at any given time. express Constant pressure on the mold, express Constant pressure on the mold, Represents the step size sequence. express Constant pressure control deviation of the push rod; S4: When the mold is fully closed, the upper mold pressure reaches the set pressure threshold and enters the pressure holding state. If the ejection and passive retraction pressure of the mold ejector cylinder decreases to the set threshold, the forward port of the proportional directional valve opens, and the proportional pressure reducing valve adjusts the output value of the proportional pressure reducing valve according to formula (6) to achieve pressure compensation. （6）； in: express The control output value of the proportional pressure reducing valve at any given time. This represents the proportional adjustment coefficient. This represents the integral adjustment coefficient. express The difference between the target pressure and the real-time pressure of the proportional pressure reducing valve. This represents the differential adjustment coefficient.

2. The product injection molding method based on thermoplastic carbon fiber composite material according to claim 1, characterized in that: In step S2, the upper mold position curve is given by equation (1), the ejector pin position curve is given by equation (2), and the fitting curve of the upper mold position curve and the ejector pin position curve is given by equation (3). （1）； （2）； （3）； in: express The position of the upper mold at all times. This represents the quadratic fitting coefficient of the upper mold position curve. This represents the fitting coefficient of the first-order term of the upper mold position curve. This represents the fitting coefficient of the constant term of the upper mold position curve. express The position of the push rod at all times. This represents the quadratic fitting coefficient of the pushrod position curve. This represents the fitting coefficient of the first-order term of the pushrod position curve. This represents the fitting coefficient of the constant term of the push rod position curve.

3. The product injection molding method based on thermoplastic carbon fiber composite material according to claim 1, characterized in that: In step S2, when the upper die reaches the set lowering position but has not yet contacted the ejector pin, the downward speed of the upper die increases to the set downward speed, and the downward speed of the ejector pin is calculated according to equation (4), so that the ejector pin moves downward ahead of time according to the calculated downward speed: （4）； in: Indicates the downward speed of the push rod. Indicates the damping factor. This indicates the downward speed of the upper mold.

4. The product injection molding method based on thermoplastic carbon fiber composite material according to claim 1, characterized in that: In step S2, an upper mold position sensor is used to sense the position of the upper mold, and the upper mold position sensor transmits the sensed upper mold position information to the programmable controller. An ejector pin position sensor is used to sense the position of the ejector pin, and the ejector pin position sensor transmits the sensed ejector pin position information to the programmable controller.

5. The product injection molding method based on thermoplastic carbon fiber composite material according to claim 1, characterized in that: It also includes step S5: after the pressure holding ends, the upper mold is demolded and returned, the workpiece is pressed and formed, the programmable controller controls the proportional directional valve to open the reverse interface, controls the proportional pressure reducing valve to output pressure, so that the ejector rod completes the retraction action under constant pressure and flow, and the product forms a reserved hole at the retraction position.

6. A product injection system based on thermoplastic carbon fiber composite material, used to perform a product injection method based on thermoplastic carbon fiber composite material as described in any one of claims 1 to 5, characterized in that: The system includes a mold unit, a programmable logic controller (PLC), and an auxiliary hydraulic control unit. The mold unit comprises an upper mold, a lower mold, an ejector platform, ejector pins, and ejector pin cylinders. The ejector pins are mounted on the ejector platform and pass through a pre-drilled hole in the lower mold. The ejector pin cylinders are mounted on the lower mold and drive the ejector platform to move up and down. The auxiliary hydraulic control unit includes an active retraction oil circuit for the ejector pin cylinder and an ejection and passive retraction oil circuit connected to the ejector pin cylinder. The active retraction oil circuit is equipped with an active retraction oil circuit pressure sensor, a proportional directional valve, and a proportional pressure reducing valve. The ejection and passive retraction oil circuits are equipped with... The device includes pressure sensors for the push rod cylinder's push-out and passive retraction oil circuits, a push rod passive retraction switch valve, and a proportional relief valve. The push rod cylinder active retraction oil circuit pressure sensor detects the pressure data in the push rod cylinder's active retraction oil circuit and transmits the pressure data to the programmable controller. The push rod cylinder push-out and passive retraction oil circuit pressure sensors detect the pressure data in the push rod cylinder's push-out and passive retraction oil circuits and transmit the pressure data to the programmable controller. The programmable controller controls the output of the proportional pressure reducing valve, the switching of the proportional directional valve, the opening and closing of the push rod passive retraction switch valve, and the output of the proportional relief valve.

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