Dynamic pressure and speed monitoring method for ejector pin of injection molding machine

Abstract

The invention discloses a dynamic pressure and speed monitoring method for an ejector pin of an injection molding machine, and the method comprises the steps: obtaining a standard pressure curve corresponding to each pressure data set through a cubic spline interpolation method based on the pressure data sets corresponding to multiple ejector pin rollback processes; forming a pressure envelope curve through the first preset deviation and each standard pressure curve; acquiring a speed data set corresponding to a plurality of ejector pin strokes; a cubic spline interpolation method is used for fitting ejector pin speed point positions in all the speed data sets, and a speed standard range is obtained; in the working process of the ejector pin, the real-time speed of the ejector pin and the real-time pressure value of the ejector pin oil way are obtained, and whether the two are within the speed standard range and the pressure envelope curve or not is judged; and if the real-time speed of the ejector pin exceeds the speed standard range or the real-time pressure value exceeds the pressure envelope curve, the power supply of the injection molding machine is cut off, and alarm information is sent, so that dynamic monitoring of the pressure and the speed of the ejector pin of the injection molding machine at each position is realized.

Description

Technical Field

[0001] The invention relates to the field of injection molding machines, and in particular to a method for monitoring the dynamic pressure and speed of an ejector pin of an injection molding machine. Background Art

[0002] In the current automated production environment, when the injection molding machine completes the mold opening, the ejector will move forward to push the product out, waiting for manual or robotic removal of the product. However, there are some problems with this process. First, customers may get their hands pinched due to improper operation when taking the product. Second, if the product fails to completely leave the mold or foreign matter enters the mold, the ejector may damage the mold when closing the mold after retraction. Summary of the invention

[0003] In order to detect the dynamic pressure and speed of the ejector pin of an injection molding machine in real time at each position, and to promptly cut off the power supply of the injection molding machine and send an alarm message when an abnormality occurs, thereby reducing the risk of personal injury caused by operator error and preventing the problem of mold damage caused by foreign matter stuck in the mold cavity, the present invention proposes a method for monitoring the dynamic pressure and speed of the ejector pin of an injection molding machine, comprising:

[0004] During the ejector retraction process, the real-time position of the ejector and the real-time pressure value of the corresponding ejector oil circuit are obtained;

[0005] Get the time point t in the ejector stroke i The corresponding ejector pin position x(t i ), where t i is a discrete time point, i represents the time sequence number;

[0006] Based on the pressure data sets corresponding to the multiple ejector retraction processes, a standard pressure curve corresponding to each pressure data set is obtained by using a cubic spline interpolation method; the pressure data set includes: the real-time position of the ejector sampled at intervals and the real-time pressure value of the corresponding ejector oil circuit; a pressure envelope curve is formed by a first preset deviation and each standard pressure curve; the pressure data set corresponds to the ejector retraction process one by one;

[0007] Acquire a plurality of speed data sets corresponding to ejector strokes; the speed data sets correspond to ejector strokes one by one; the speed data sets include: the ejector position x(t i ), and according to the ejector position x(t i ) The calculated ejector velocity point v(x(t i ));

[0008] The ejector speed points in each speed data set are fitted by using the cubic spline interpolation method to obtain the speed position curve corresponding to each speed data set; a speed envelope curve is formed by using the second preset deviation and each speed position curve, and the upper and lower limits of the ejector speed are set by using the speed envelope curve to obtain the speed standard range;

[0009] During the working process of the ejector, the real-time speed of the ejector and the real-time pressure value of the ejector oil circuit are obtained to determine whether the two fall within the speed standard range and the pressure envelope curve respectively; if the real-time speed of the ejector exceeds the speed standard range, or the real-time pressure value exceeds the pressure envelope curve, the power supply of the injection molding machine is cut off and an alarm message is sent.

[0010] Furthermore, the monitoring method further comprises:

[0011] During the operation of the injection molding machine, the pressure envelope curve is updated in real time based on the pressure data set corresponding to the previous n ejector retraction processes of the current time, and the speed standard range is updated based on the speed data set corresponding to the previous n ejector strokes of the current time.

[0012] Furthermore, the standard pressure curve indicates that the corresponding pressure data set is data obtained when the ejector is in a normal operating state.

[0013] Furthermore, obtaining a standard pressure curve corresponding to the pressure data set specifically includes:

[0014] A cubic polynomial satisfying a preset condition is constructed for each two adjacent data points in the pressure data set; the abscissa of the data point is the real-time position of the ejector pin, and the ordinate is the real-time pressure value;

[0015] The expression of the cubic polynomial is:

[0016] S i (x(t)) = a i +b i (x(t)-x(t i ))+c i (x(t)-x(t i )) 2 +d i (x(t)-x(t i )) 3 ;in:

[0017] a, b, c, and d are polynomial coefficients, respectively, and x(t) represents the ejector position variable;

[0018] Solve the polynomial coefficients of each cubic polynomial based on preset conditions;

[0019] The interpolation segments corresponding to the cubic polynomials obtained by the solution are combined to obtain the standard pressure curve.

[0020] Furthermore, the preset condition is:

[0021] The first-order derivatives of adjacent cubic polynomials are equal at the intersection points;

[0022] The second-order derivatives of adjacent cubic polynomials are equal at the intersection points;

[0023] In the interval [x(t i ), x(t i+1 )], S i (x) passes through the data point (x(t i ), y i ) and (x(t i+1 ), y i+1 ), where y i Indicates the real-time pressure value.

[0024] Furthermore, the first-order derivatives of the adjacent cubic polynomials are equal at the intersection point, and the corresponding formula expression is:

[0025]

[0026] The second-order derivatives of the adjacent cubic polynomials are equal at the intersection point, and the corresponding formula expression is:

[0027] S″ i (x(t i+1 ))=2c i +6d i (x(t i+1 )-x(t i ))=S″ i+1 (x(t i+1 ));

[0028] In the interval [x(t i ), x(t i+1 )], S i (x) passes through the data point (x(t i ), y i ) and (x(t i+1 ), y i+1 ), the corresponding formula expression is:

[0029] S i (x(t i ))=a i +b i (x(t i )-x(t i ))+c i (x(t i )-x(t i )) 2+d i (x(t i )-x(t i )) 3 =y i

[0030] S i (x(t i+1 ))=a i +b i (x(t i+1 )-x(t i ))+c i (x(t i+1 )-x(t i )) 2 +d i (x(t i+1 )-x(t i )) 3 =y i+1 .

[0031] Furthermore, the ejector speed point v(x(t i )) is calculated as:

[0032]

[0033] Furthermore, the function expression of the upper envelope curve in the pressure envelope curve is:

[0034] P up-envelope (x(t i ))=max(P1(x(t i )), P2(x(t i )), P3(x(t i ))..., P n (x(t i )))+e1;

[0035] The function expression of the lower envelope curve in the pressure envelope curve is:

[0036] P down-envelope (x(t i ))=min(P1(x(t i )), P2(x(t i )), P3(x(t i ))..., P n (x(t i )))-e1;

[0037] Where n represents the number of standard pressure curves, P j (x(t i)) represents the jth standard pressure curve, j=1..·n; e1 represents the first preset deviation.

[0038] Furthermore, the function expression of the upper envelope curve in the velocity envelope curve is:

[0039] V up (x(t i ))=max(V(x(t1)), V(x(t2)),..., V(x(t) n )))+e2;

[0040] The function expression of the lower envelope curve in the velocity envelope curve is:

[0041] V down (x(t i ))=min(V(x(t1)), V(x(t2)),..., V(x(t) n )))-e2;

[0042] In the formula, V(x(t i )) represents the i-th speed-position curve, i=1…n, n represents the number of speed-position curves, and e2 represents the second preset deviation.

[0043] Furthermore, the ejector stroke includes an ejection and retraction process of the ejector.

[0044] Compared with the prior art, the present invention has at least the following beneficial effects:

[0045] (1) The present invention uses a cubic spline interpolation method to obtain a standard pressure curve corresponding to each pressure data set based on a pressure data set corresponding to multiple ejector retraction processes; forms a pressure envelope curve through a first preset deviation and each standard pressure curve; obtains a speed data set corresponding to multiple ejector strokes; uses a cubic spline interpolation method to fit the ejector speed points in each speed data set to obtain a speed standard range; during the ejector operation process, obtains the real-time speed of the ejector and the real-time pressure value of the ejector oil circuit, and determines whether the two fall within the speed standard range and the pressure envelope curve respectively; if the real-time speed of the ejector exceeds the speed standard range, or the real-time pressure value exceeds the pressure envelope curve, the power supply of the injection molding machine is cut off and an alarm message is sent, which realizes dynamic monitoring of the pressure and speed of the ejector of the injection molding machine at each position, reduces the risk of personal injury caused by operator error, and prevents the problem of mold damage caused by foreign matter stuck in the mold cavity;

[0046] (2) During the operation of the injection molding machine, the present invention updates the pressure envelope curve in real time based on the pressure data set corresponding to the previous n ejector retraction processes of the current time, and updates the speed standard range based on the speed data set corresponding to the previous n ejector strokes of the current time, thereby achieving accurate early warning of the ejector operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Figure 1 The present invention is a flow chart of a method for monitoring the dynamic pressure and speed of an ejector pin of an injection molding machine;

[0048] Figure 2 Schematic diagram of the two-dimensional coordinates corresponding to the pressure data set. DETAILED DESCRIPTION

[0049] The following are specific embodiments of the present invention and the accompanying drawings to further describe the technical solution of the present invention, but the present invention is not limited to these embodiments.

[0050] In order to detect the dynamic pressure and speed of the ejector pin of the injection molding machine in real time at each position, and to cut off the power supply of the injection molding machine and send an alarm message in time when an abnormality occurs, thereby reducing the risk of personal injury caused by operator errors and preventing mold damage caused by foreign objects stuck in the mold cavity, such as Figure 1 As shown, the present invention proposes a method for monitoring the dynamic pressure and speed of an injection molding machine ejector pin, comprising:

[0051] During the ejector retraction process, the real-time position of the ejector and the real-time pressure value of the corresponding ejector oil circuit are obtained;

[0052] In this embodiment, a pressure sensor is installed on the ejector oil circuit to obtain a real-time pressure value.

[0053] Get the time point t in the ejector stroke i The corresponding ejector pin position x(t i ), where t i is a discrete time point, i represents a time sequence number; the ejector stroke includes the ejection and retraction process of the ejector.

[0054] Based on the pressure data sets corresponding to multiple ejector pin retraction processes, the standard pressure curve corresponding to each pressure data set is obtained using the cubic spline interpolation method; Figure 2 As shown, the pressure data set includes: the real-time position of the ejector pin sampled at intervals (interval time is 2ms) and the real-time pressure value of the corresponding ejector pin oil circuit; a pressure envelope curve is formed by a first preset deviation and each standard pressure curve; the pressure data set corresponds to the ejector pin retraction process one by one;

[0055] The standard pressure curve indicates that the corresponding pressure data set is data obtained when the ejector is in normal operating state.

[0056] Get the standard pressure curve corresponding to the pressure data set, including:

[0057] A cubic polynomial satisfying a preset condition is constructed for each two adjacent data points in the pressure data set; the abscissa of the data point is the real-time position of the ejector pin, and the ordinate is the real-time pressure value;

[0058] The expression of the cubic polynomial is:

[0059] S i (x(t)) = a i +b i (x(t)-x(t i ))+c i (x(t)-x(t i )) 2 +d i (x(t)-x(t i )) 3 ;in:

[0060] a, b, c, and d are polynomial coefficients, respectively, and x(t) represents the ejector position variable;

[0061] Solve the polynomial coefficients of each cubic polynomial based on preset conditions;

[0062] The interpolation segments corresponding to the cubic polynomials obtained by the solution are combined to obtain the standard pressure curve.

[0063] The preset conditions are:

[0064] The first-order derivatives of adjacent cubic polynomials are equal at the intersection points;

[0065] The first-order derivatives of the adjacent cubic polynomials are equal at the intersection point, and the corresponding formula expression is:

[0066]

[0067] The second-order derivatives of adjacent cubic polynomials are equal at the intersection points;

[0068] The second-order derivatives of the adjacent cubic polynomials are equal at the intersection point, and the corresponding formula expression is:

[0069] S″ i (z(t i+1 ))=2c i +6d i (x(t i+1 )-x(t i ))=S″ i+1 (x(t i+1 ));

[0070] It should be noted that in order to make the curve smooth, it is necessary to ensure that the first-order derivatives of adjacent polynomials are equal at the intersection points. Similarly, it is also necessary to ensure that the second-order derivatives of adjacent polynomials are equal at the intersection points.

[0071] In the interval [x(t i ), x(t i+1 )], S i (x) passes through the data point (x(t i ), y i ) and (x(t i+1 ), y i+1 ), where y i Indicates the real-time pressure value.

[0072] In the interval [x(t i ), x(t i+1 )], S i (x) passes through the data point (x(t i ), y i ) and (x(t i+1 ), y i+1 ), the corresponding formula expression is:

[0073] S i (x(t i ))=a i +b i (x(t i )-x(t i ))+c i (x(t i )-x(t i )) 2 +d i (x(t i )-x(t i )) 3 =y i

[0074] S i (x(t i+1 ))=a i +b i (x(t i+1 )-x(t i ))+c i (x(t i+1 )-x(t i )) 2 +d i (x(t i+1 )-x(t i )) 3 =y i+1 .

[0075] Through the equations corresponding to the above preset conditions, a linear equation system containing all interval endpoint information can be constructed. For n intervals (two adjacent data points are one interval), there will be 4n unknowns (because each interval has four coefficients) and the same number of equations. These equations can be written in matrix form Ax=b, where: A is the coefficient matrix, x is the unknown vector (containing all a i , b i , c i , d i ), b is a vector of constant terms on the right. Finally, the coefficients of each cubic polynomial can be obtained by solving x using standard linear equation solving methods (such as Gaussian elimination, LU decomposition, etc.).

[0076] The function expression of the upper envelope curve in the pressure envelope curve is:

[0077] P up-envelope (x(t i ))=max(P1(x(t i )), P2(x(t i )), P3(x(t i ))..., P n (x(t i )))+e1;

[0078] The function expression of the lower envelope curve in the pressure envelope curve is:

[0079] P down-envelope (x(t i ))=min(P1(x(t i )), P2(x(t i )), P3(x(t i ))..., P n (x(t i )))-e1;

[0080] Where n represents the number of standard pressure curves, P j (x(t i )) represents the jth standard pressure curve, j=1…n; e1 represents the first preset deviation.

[0081] Acquire a plurality of speed data sets corresponding to ejector strokes; the speed data sets correspond to ejector strokes one by one; the speed data sets include: the ejector position x(t i ), and according to the ejector position x(t i ) The calculated ejector velocity point v(x(t i ));

[0082] It should be noted that, in this embodiment, the velocity envelope curve is formed or updated, and the velocity data sets used are all data obtained when the ejector is in normal operating state.

[0083] The ejector speed point v(x(t i )) is calculated as:

[0084]

[0085] The ejector speed points in each speed data set are fitted by using a cubic spline interpolation method to obtain a speed position curve corresponding to each speed data set; a speed envelope curve is formed by using a second preset deviation and each speed position curve, and the upper and lower limits of the ejector speed are set by using the speed envelope curve to obtain a speed standard range; the speed data set corresponds to the speed position curve one by one;

[0086] It should be noted that, in this embodiment, the acquisition method of the velocity position curve is the same as that of the standard pressure curve, and both are obtained by fitting through the cubic spline interpolation method. In simple terms, it includes:

[0087] 1. For each adjacent data point in the velocity data set:

[0088] (x(t i ), v(x(t i ))) and (x(t i+1 ), v(x(t i+1 ))), both connect the two points by setting a cubic polynomial; the formula of the cubic polynomial is:

[0089] S i (x(t)) = a i +b i (x(t)-x(t i ))+c i (x(t)-x(t i )) 2 +d i (x(t)-x(t i )) 3 ;

[0090] 2. Within each interpolation segment, the cubic polynomial S i (x(t)) should satisfy the following conditions:

[0091] S i (x(t i ))=v(x(t i ));

[0092] S i (x(t i+1 ))=v(x(ti+1 ));

[0093] S′ i (x(t i ))=S′ i-1 (x(t i-1 )); (the first-order derivative is continuous at the endpoints);

[0094] S″ i (x(t i ))=S″ i-1 (x(t i-1 )); (the second-order derivative is continuous at the endpoints);

[0095] A linear equation system is constructed based on these conditions, and the polynomial coefficients of each cubic polynomial are obtained by solving the equation system; the interpolation segments corresponding to each cubic polynomial obtained by combining the solved interpolation segments are obtained to obtain the velocity position curve V(x(t i )).

[0096] The function expression of the upper envelope curve in the velocity envelope curve is:

[0097] V up (x(t i ))=max(V(x(t1)), V(x(t2)),..., V(x(t) n )))+e2;

[0098] The function expression of the lower envelope curve in the velocity envelope curve is:

[0099] V down (x(t i ))=min(V(x(t1)), V(x(t2)),..., V(x(t) n )))-e2;

[0100] In the formula, V(x(t i )) represents the i-th speed-position curve, i=1…n, n represents the number of speed-position curves, and e2 represents the second preset deviation.

[0101] It should be noted that, in the present invention, the upper and lower limits of the ejector speed are the maximum value and the minimum value of the speed envelope curve, respectively.

[0102] During the working process of the ejector, the real-time speed of the ejector and the real-time pressure value of the ejector oil circuit are obtained to determine whether the two fall within the speed standard range and the pressure envelope curve respectively; if the real-time speed of the ejector exceeds the speed standard range, or the real-time pressure value exceeds the pressure envelope curve, the power supply of the injection molding machine is cut off and an alarm message is sent.

[0103] The monitoring method further comprises:

[0104] During the operation of the injection molding machine, the pressure envelope curve is updated in real time based on the pressure data set corresponding to the previous n ejector retraction processes of the current time, and the speed standard range is updated based on the speed data set corresponding to the previous n ejector strokes of the current time.

[0105] The invention is based on a pressure data set corresponding to multiple ejector retraction processes, and uses a cubic spline interpolation method to obtain a standard pressure curve corresponding to each pressure data set; a pressure envelope curve is formed by a first preset deviation and each standard pressure curve; a speed data set corresponding to multiple ejector strokes is obtained; the ejector speed points in each speed data set are respectively fitted by the cubic spline interpolation method to obtain a speed standard range; during the ejector working process, the real-time speed of the ejector and the real-time pressure value of the ejector oil circuit are obtained, and it is judged whether the two fall within the speed standard range and the pressure envelope curve respectively; if the real-time speed of the ejector exceeds the speed standard range, or the real-time pressure value exceeds the pressure envelope curve, the power supply of the injection molding machine is cut off and an alarm message is sent, so that dynamic monitoring of the pressure and speed of the ejector of the injection molding machine at each position is realized, the risk of personal injury caused by operator operation errors is reduced, and the problem of mold damage caused by foreign matter stuck in the mold cavity is prevented.

[0106] It should be noted that all directional indications in the embodiments of the present invention (such as up, down, left, right, front, back, etc.) are only used to explain the relative position relationship, movement status, etc. between the components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0107] In addition, in the present invention, descriptions such as "first", "second", "one", etc. are only used for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" or "second" may explicitly or implicitly include at least one of the features. In the description of the present invention, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0108] In the present invention, unless otherwise clearly specified and limited, the terms "connection", "fixation", etc. should be understood in a broad sense. For example, "fixation" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0109] In addition, the technical solutions between the various embodiments of the present invention can be combined with each other, but it must be based on the fact that ordinary technicians in the field can implement it. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

Claims

1. A method for monitoring the dynamic pressure and speed of an injection molding machine ejector pin, characterized in that: include: During the ejector retraction process, the real-time position of the ejector and the real-time pressure value of the corresponding ejector oil circuit are obtained; Get the time point t in the ejector stroke i The corresponding ejector pin position x(t i ), where t i is a discrete time point, i represents the time sequence number; Based on the pressure data sets corresponding to the multiple ejector retraction processes, a standard pressure curve corresponding to each pressure data set is obtained by using a cubic spline interpolation method; the pressure data set includes: the real-time position of the ejector sampled at intervals and the real-time pressure value of the corresponding ejector oil circuit; a pressure envelope curve is formed by a first preset deviation and each standard pressure curve; the pressure data set corresponds to the ejector retraction process one by one; Acquire a plurality of speed data sets corresponding to ejector strokes; the speed data sets correspond to ejector strokes one by one; the speed data sets include: the ejector position x(t i ), and according to the ejector position x(t i ) The calculated ejector velocity point v(x(t i )); The ejector speed points in each speed data set are fitted by using the cubic spline interpolation method to obtain the speed position curve corresponding to each speed data set; a speed envelope curve is formed by using the second preset deviation and each speed position curve, and the upper and lower limits of the ejector speed are set by using the speed envelope curve to obtain the speed standard range; During the working process of the ejector, the real-time speed of the ejector and the real-time pressure value of the ejector oil circuit are obtained to determine whether the two fall within the speed standard range and the pressure envelope curve respectively; if the real-time speed of the ejector exceeds the speed standard range, or the real-time pressure value exceeds the pressure envelope curve, the power supply of the injection molding machine is cut off and an alarm message is sent.

2. The method for monitoring dynamic pressure and speed of ejector pin of injection molding machine according to claim 1, characterized in that: The monitoring method further comprises: During the operation of the injection molding machine, the pressure envelope curve is updated in real time based on the pressure data set corresponding to the previous n ejector retraction processes of the current time, and the speed standard range is updated based on the speed data set corresponding to the previous n ejector strokes of the current time.

3. The method for monitoring dynamic pressure and speed of ejector pin of injection molding machine according to claim 1, characterized in that: The standard pressure curve indicates that the corresponding pressure data set is data obtained when the ejector is in normal operating state.

4. The method for monitoring dynamic pressure and speed of ejector pin of injection molding machine according to claim 3, characterized in that: Get the standard pressure curve corresponding to the pressure data set, including: A cubic polynomial satisfying a preset condition is constructed for each two adjacent data points in the pressure data set; the abscissa of the data point is the real-time position of the ejector pin, and the ordinate is the real-time pressure value; The expression of the cubic polynomial is: S i (x(t))=a i +b i (x(t)-x(t i ))+c i (x(t)-x(t i )) 2 +d i (x(t)-x(t i )) 3 ; in: a, b, c, and d are polynomial coefficients, respectively, and x(t) represents the ejector position variable; Solve the polynomial coefficients of each cubic polynomial based on preset conditions; The interpolation segments corresponding to the cubic polynomials obtained by the solution are combined to obtain the standard pressure curve.

5. The method for monitoring dynamic pressure and speed of ejector pin of injection molding machine according to claim 4, characterized in that: The preset conditions are: The first-order derivatives of adjacent cubic polynomials are equal at the intersection points; The second-order derivatives of adjacent cubic polynomials are equal at the intersection points; In the interval [x(t i ), x(t i+1 )], S f (x) passes through the data point (x(t i ), y i ) and (x(t i+1 ), y i+1 ), where y i Indicates the real-time pressure value.

6. The method for monitoring dynamic pressure and speed of ejector pin of injection molding machine according to claim 5, characterized in that: The first-order derivatives of the adjacent cubic polynomials are equal at the intersection point, and the corresponding formula expression is: S′ i (x(t i+1 ))=b i +2c i (x(t i+1 )-x(t i ))+3d i (x(t i+1 )-x(t i )) 2 =S i+1 (x(t i+1 )); The second-order derivatives of the adjacent cubic polynomials are equal at the intersection point, and the corresponding formula expression is: S″ i (x(t i+1 ))=2c i +6d i (x(t i+1 )-x(t i ))=S″ i+1 (x(t i+1 )); In the interval [x(t i ), x(t i+1 )], S i (x) passes through the data point (x(t i ), y i ) and (x(t i+1 ), y i+1 ), the corresponding formula expression is: S i (x(t i ))=a i +b i (x(t i )-x(t i ))+c i (x(t i )-x(t i )) 2 +d i (x(t i )- x(t i )) 3 =y i S i (x(t i+1 ))=a i +b i (x(t i+1 )-x(t i ))+c i (x(t i+1 )-x(t i )) 2 +d i (x(t i+1 )-x(t i )) 3 =y i+1 。 7. The method for monitoring dynamic pressure and speed of ejector pin of injection molding machine according to claim 6, characterized in that: The ejector speed point v(x(t i )) is calculated as:

8. The method for monitoring dynamic pressure and speed of ejector pin of injection molding machine according to claim 7, characterized in that: The function expression of the upper envelope curve in the pressure envelope curve is: P np-envelope (x(t i ))=max(P1(x(t i )),P2(x(t i )),P3(x(t i ))...,P n (x(t i )))+e1; The function expression of the lower envelope curve in the pressure envelope curve is: P down-envelope (x(t i ))=min(P1(x(t i )),P2(x(t i )),P3(x(t i ))...,P n (x(t i )))-e1; Where n represents the number of standard pressure curves, P j (x(t i )) represents the jth standard pressure curve, j=1...n; e1 represents the first preset deviation.

9. The method for monitoring dynamic pressure and speed of ejector pin of injection molding machine according to claim 8, characterized in that: The function expression of the upper envelope curve in the velocity envelope curve is: V up (x(t i ))=max(V(x(t1)),V(x(t2)),...,V(x(t n )))+e2; The function expression of the lower envelope curve in the velocity envelope curve is: V down (x(t i ))=min(V(x(t1)),V(x(t2)),...,V(x(t n )))-e2; In the formula, V(x(t i )) represents the i-th speed-position curve, i=1...n, n represents the number of speed-position curves, and e2 represents the second preset deviation.

10. The method for monitoring dynamic pressure and speed of ejector pin of injection molding machine according to claim 1, characterized in that: The ejector stroke includes the ejection and retraction processes of the ejector.

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