Disclosure of Invention
In order to overcome the defects and shortcomings in the prior art, the invention provides a device for monitoring the abrasion state of a check valve of an injection molding machine on line.
The second purpose of the invention is to provide a method for monitoring the abrasion state of the check valve of the injection molding machine on line.
In order to achieve the purpose, the invention adopts the following technical scheme:
a device for monitoring the abrasion state of a check valve of an injection molding machine on line is provided with a microprocessor, and further comprises a linear displacement sensor, a load cell pressure sensor, an injection molding machine working condition acquisition device and a terminal device, wherein the microprocessor is respectively connected with the linear displacement sensor, the load cell pressure sensor, the injection molding machine working condition acquisition device and the terminal device, and the injection molding machine working condition acquisition device is also connected with the injection molding machine;
the linear displacement sensor, the load cell pressure sensor and the injection molding machine working condition acquisition device are all arranged on the injection molding machine, the linear displacement sensor is used for acquiring screw displacement information, the load cell pressure sensor is used for acquiring screw stress information, and the injection molding machine working condition acquisition device is used for acquiring injection molding working condition information;
the microprocessor is used for forming injection molding input data according to the screw displacement information, the screw stress information and the injection molding working condition information, outputting the abrasion degree of the check valve, setting different levels of abrasion state thresholds and determining the abrasion state of the check valve according to the abrasion degree of the check valve and the different levels of abrasion state thresholds;
the terminal equipment is used for displaying the abrasion state of the check valve.
Preferably, the linear displacement sensor is disposed at a distal end side of the screw.
Preferably, the load cell pressure sensor is provided at a distal end edge portion of the screw.
As the preferred technical scheme, the injection molding machine working condition acquisition device is randomly arranged on the injection molding machine.
As a preferred technical solution, the injection molding condition information specifically includes an injection speed, a minimum padding, a V/P conversion point, and a raw material process condition.
As a preferred technical scheme, the raw material process conditions comprise melt index performance indexes.
In order to achieve the second object, the invention adopts the following technical scheme:
a method for monitoring the abrasion state of a check valve of an injection molding machine on line comprises the following steps:
and (3) acquiring injection molding data: acquiring screw displacement information, screw stress information and injection molding working condition information;
acquiring and processing injection molding data: converting the screw displacement information and the screw stress information from analog signals into digital signals, and performing fitting processing based on the screw displacement information and the screw stress information to form injection molding process data, wherein the injection molding process data comprises a load cell pressure curve and a screw displacement curve;
an injection molding characteristic set generation step: extracting data characteristics based on injection molding process data and performing characteristic vectorization by combining injection molding working condition information to obtain an injection molding characteristic set, wherein the data characteristics comprise a maximum value, a mean value, a covariance, a skewness and power consumption of single injection molding;
predicting the abrasion state of the check valve: and predicting based on the injection molding feature set and a check valve wear state evaluation model after machine learning training, and determining the wear state of the check valve.
As a preferred technical scheme, the training data acquisition step specifically sets the injection molding machine to acquire the training data at the same temperature, the same injection speed and the same material.
As a preferred technical scheme, the injection molding feature set generating step specifically comprises the following steps:
extracting injection molding process data, extracting first data characteristics, forming a first injection molding data characteristic matrix based on the first data characteristics, and performing characteristic vectorization on the first injection molding data characteristic matrix to obtain a first characteristic vector of a single injection molding sample;
and calculating the power consumption of single injection molding by combining a load cell pressure curve and a screw displacement curve and adopting an injection molding power consumption formula, wherein the injection molding power consumption formula specifically comprises the following steps:
w=∫floadcell(t)·f’position(t)dt
wherein f isloadcell(t) represents a load cell pressure curve function, f'position(t) represents screw speed, w represents screw work of single injection molding, and t represents time variable;
adding the screw work w of single injection molding into the first characteristic vector of the injection molding sample to obtain a second characteristic vector of the injection molding sample, and performing characteristic vectorization by combining the second characteristic vector of the injection molding sample and injection molding condition information to form a third characteristic vector of the injection molding sample;
and integrating the third feature vectors of all injection molding samples into one injection molding feature set.
As a preferable technical solution, in the check valve wear state prediction step, the check valve wear state estimation model after machine learning training is established by using the following steps:
a wear state simulation step: the check valves with different degrees of wear defects are manufactured respectively to simulate the check valves with different degrees of wear states, and the check valves with different wear states are simulated by forming notches with different depths between the bolt rubber ring and the injection rubber medium;
a training data acquisition step: acquiring screw displacement information, screw stress information and injection molding condition information under different wear states of the check valve;
training data acquisition and processing steps: converting the screw displacement information and the screw stress information from analog signals into digital signals, and performing fitting processing based on the screw displacement information and the screw stress information to form injection molding process data, wherein the injection molding process data comprises a load cell pressure curve and a screw displacement curve;
a training set generation step: extracting data characteristics based on the injection molding process data, performing characteristic vectorization by combining injection molding working condition information to obtain an injection molding characteristic set, and forming an injection molding training set by using the abrasion degree of the check valve as a training label;
training: and establishing a check valve wear state evaluation model by using a machine learning algorithm, and finishing training when the preset training times are reached and the test accuracy value of the check valve wear degree reaches a preset test accuracy threshold value, thus obtaining the trained check valve wear state evaluation model.
Compared with the prior art, the invention has the following advantages and beneficial effects:
(1) according to the invention, the load cell pressure sensor and the linear displacement sensor are respectively arranged at the rear part of the screw and the moving end of the screw, so that the on-line monitoring of the abrasion state of the check valve is realized on the premise of not damaging the structure of the injection molding machine; the method has the advantages that the data characteristics of the process data are extracted, the working condition data are combined, the abrasion state evaluation model of the check valve is established based on the algorithm of machine learning, the evaluation model can be well suitable for the injection molding industry with various working condition characteristics, a certain generalization effect is achieved, the abrasion state of the check valve is obtained through monitoring, factories and enterprises are helped to avoid unnecessary periodic detection and maintenance, and a large amount of maintenance cost is reduced.
Detailed Description
In the description of the present disclosure, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, and are only for convenience of describing and simplifying the present disclosure, but do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and thus, should not be construed as limiting the present disclosure.
Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance. Also, the use of the terms "a," "an," or "the" and similar referents do not denote a limitation of quantity, but rather denote the presence of at least one. The word "comprising" or "comprises", and the like, means that the element or item appearing before the word covers the element or item listed after the word and its equivalents, but does not exclude other elements or items. The terms "connected" or "coupled" and the like are not restricted to physical or mechanical connections, but may include electrical connections, whether direct or indirect.
In the description of the present disclosure, it is to be noted that the terms "mounted," "connected," and "connected" are to be construed broadly unless otherwise explicitly stated or limited. For example, the connection can be fixed, detachable or integrated; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meaning of the above terms in the present disclosure can be understood in specific instances by those of ordinary skill in the art. In addition, technical features involved in different embodiments of the present disclosure described below may be combined with each other as long as they do not conflict with each other.
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
Examples
Example 1
As shown in fig. 1 and fig. 2, the present embodiment provides a device for online monitoring of a wear state of a check valve of an injection molding machine, the device includes a linear displacement sensor 2, a load cell pressure sensor 3, an injection molding machine working condition acquisition device, a microprocessor 4, and a terminal device 5, the microprocessor 4 is respectively connected with the linear displacement sensor 2, the load cell pressure sensor 3, the injection molding machine working condition acquisition device, and the terminal device 5, and the injection molding machine working condition acquisition device is further connected with the injection molding machine 1. Wherein the injection molding machine 1 is provided with a screw.
Referring to fig. 1, an injection molding machine operating condition acquisition device is used as a lower computer of an injection molding machine 1, and a linear displacement sensor 2, a load cell pressure sensor 3 and the injection molding machine operating condition acquisition device are all arranged in the injection molding machine 1.
Referring to fig. 1, the linear displacement sensor 2 is disposed at one side of the end of the screw, specifically, one end of the linear displacement sensor 2 is mounted on a fixed support of the injection platform of the injection molding machine, the other end of the linear displacement sensor 2 is mounted on a movable plasticizing screw support frame, and the linear displacement sensor 2 is used for collecting screw displacement information. The load cell pressure sensor 3 is arranged at the end edge part of the screw, and the load cell pressure sensor 3 is used for collecting the stress information of the screw. The injection molding machine working condition acquisition device is used for acquiring injection molding working condition information, and can be randomly arranged on the injection molding machine, wherein the injection molding working condition information specifically comprises an injection speed, a minimum padding, a V/P conversion point and raw material process conditions, and the raw material process conditions comprise performance indexes such as a melt index.
In this embodiment, the microprocessor 4 is configured to convert the screw displacement information and the screw stress information from analog signals to digital signals, perform fitting processing on the screw displacement information and the screw stress information to form injection molding process data, form injection molding input data by combining the injection molding process data and the injection molding condition information, output the wear degree of the check valve, set different levels of wear state thresholds, and determine the wear state of the check valve according to the wear degree of the check valve and the different levels of wear state thresholds.
During actual application, the microprocessor 4 extracts data characteristics based on injection molding process data and combines injection molding working condition information to obtain an injection molding characteristic set, the injection molding characteristic set is used as injection molding input data, the abrasion degree of the check valve is predicted and output through a check valve abrasion state evaluation model, the microprocessor 4 sets abrasion state thresholds of different grades, whether the check valve of the current injection molding machine is abraded or not is determined according to the abrasion state thresholds of different grades, the abrasion of the current check valve can be accurately estimated, namely the abrasion state of the check valve is determined, and detection and maintenance are arranged in time. The data characteristics comprise the maximum value, the mean value, the covariance, the skewness and the single injection molding power consumption.
In the present embodiment, the terminal device 5 is used to display the check valve wear state. The terminal device 5 may be a desktop computer, a notebook computer, a smart phone, a PDA handheld terminal, a tablet computer, or other terminals with a display function.
Example 2
As shown in fig. 3, the embodiment provides a method for online monitoring the wear status of a check valve of an injection molding machine, which comprises the following steps:
and (3) acquiring injection molding data: screw displacement information, screw stress information and injection molding working condition information are collected. In practical application, screw displacement information is obtained through the linear displacement sensor 2, screw stress information is obtained through the load cell pressure sensor 3, and injection molding working condition information of the current injection molding machine is obtained through the injection molding machine working condition acquisition device;
acquiring and processing injection molding data: and converting the screw displacement information and the screw stress information from analog signals into digital signals, and performing fitting processing based on the screw displacement information and the screw stress information to form injection molding process data, wherein the injection molding process data comprises a load cell pressure curve and a screw displacement curve.
An injection molding characteristic set generation step: extracting data characteristics based on the injection molding process data and performing characteristic vectorization by combining injection molding working condition information to obtain an injection molding characteristic set; the data characteristics comprise the maximum value, the mean value, the covariance, the skewness and the single injection molding power consumption.
Predicting the abrasion state of the check valve: and predicting based on the injection feature set and combined with the check valve wear state evaluation model to determine the wear state of the check valve.
In the embodiment, the abrasion state of the check valve of the injection molding machine is obtained by monitoring the abrasion state of the check valve on line by a method for monitoring the abrasion state of the check valve on line, and then predictive maintenance is performed according to the abrasion state of the check valve.
In this embodiment, the step of generating the injection molding feature set specifically includes the following steps:
extracting injection molding process data, extracting first data characteristics, forming a first injection molding data characteristic matrix based on the first data characteristics, and performing characteristic vectorization on the first injection molding data characteristic matrix to obtain a first characteristic vector of a single injection molding sample;
calculating the power consumption of single injection by adopting an injection power consumption formula in combination with a load cell pressure curve and a screw displacement curve;
the injection molding power consumption formula is specifically as follows:
w=∫floadcell(t)·f’position(t)dt
wherein f isloadcell(t) represents a load cell pressure curve function, f'position(t) represents screw speed, w represents screw work of single injection molding, and t represents time variable;
adding the screw work w of single injection molding into the first characteristic vector of the injection molding sample to obtain a second characteristic vector of the injection molding sample, and performing characteristic vectorization by combining the second characteristic vector of the injection molding sample and injection molding condition information to form a third characteristic vector of the injection molding sample;
and integrating the third feature vectors of all injection molding samples into one injection molding feature set. .
The embodiment also provides a method for establishing the check valve wear state evaluation model, which comprises the following steps:
a wear state simulation step: the check valves with different degrees of wear defects are manufactured respectively to simulate the check valves with different degrees of wear states, and the check valves with different wear states are simulated by forming notches with different depths between the bolt rubber ring and the injection rubber medium;
a training data acquisition step: screw displacement information, screw stress information and injection molding condition information are acquired under different wear states of the check valve.
Training data acquisition and processing steps: and converting the screw displacement information and the screw stress information from analog signals into digital signals, and performing fitting processing based on the screw displacement information and the screw stress information to form injection molding process data, wherein the injection molding process data comprises a load cell pressure curve and a screw displacement curve.
A training set generation step: extracting data characteristics based on the injection molding process data, performing characteristic vectorization by combining injection molding working condition information to obtain an injection molding characteristic set, and forming an injection molding training set by using the abrasion degree of the check valve as a training label;
training: and establishing a check valve wear state evaluation model by using a machine learning algorithm, and finishing training when the preset training times are reached and the test accuracy value of the check valve wear degree reaches a preset test accuracy threshold value, thus obtaining the trained check valve wear state evaluation model.
In the implementation, the training data acquisition step specifically sets the injection molding machine to acquire data of all samples under the process conditions of the same temperature, the same injection speed, the same material and the like, so as to obtain a load cell pressure curve, a screw displacement curve and injection molding condition information. In practical application, the material is high density polyethylene HDPE with the same grade.
In this embodiment, the training set generating step specifically includes the following steps:
extracting data characteristics from each group of injection molding process data, wherein the data characteristics comprise a maximum value, a mean value, covariance and skewness, J represents a variable, and J represents the number of the variables;
the most value is extracted by adopting a first extraction formula:
σ=[σj1,σj2]∈RJ×2;
σj1=max xj(k),k=1,2,…,K;
σj2=min xj(k),k=1,2,…,K;
σ represents the maximum value of the injection molding process data;
the mean value is extracted by adopting a second extraction formula:
μ∈RJ×1;
μ represents the mean of the injection molding process data;
the covariance is extracted by using a third extraction formula:
Σ∈RJ×J;
Σ represents the covariance of the injection molding process data;
and extracting skewness by adopting a fourth extraction formula:
γ∈RJ×1;
gamma represents the skewness of the injection molding process data;
forming an injection molding data characteristic matrix based on the data characteristics:
performing feature vectorization on the injection molding data feature matrix, namely performing feature vectorization on the injection molding data feature matrix
Is flat as
Finally, forming a characteristic vector of the injection molding sample:
and calculating the power consumption of single injection molding by combining the load cell pressure curve, the screw displacement curve and the injection molding working condition information and adopting an injection molding power consumption formula:
w=∫floadcell(t)·f’position(t)dt
wherein f isloadcell(t) represents a load cell pressure curve function, f'position(t) represents the derivative of the screw displacement curve function, namely the screw speed, and w represents the screw work of single injection molding;
adding screw work w of single injection molding to characteristic vector of injection molding sample
In the method, the characteristic vector P of each injection molding sample is formed by combining the injection molding condition information
1×mIntegrating the feature vectors of all injection molding samples into an injection molding feature set
Label omega added with injection molding feature set
n×1Wherein the label ω of the injection feature set
n×1Specifically, the wear states are different grades, and n and m are positive integers;
performing data mining on the injection molding feature set by using a machine learning algorithm to form an injection molding training set Dn×(m+1)。
In the present embodiment, the machine learning algorithm is preferably SVR, i.e. support vector regression algorithm. The SVR adopts an epsilon-insensitive function and a kernel function algorithm to construct a linear decision function in a high-dimensional space to realize linear regression. In order to adapt to the nonlinearity of the training sample set, the SVR adopts a kernel function to solve the problem that the traditional fitting method increases the risk of overfitting when the adjustable parameters are increased. The kernel function is used for replacing a linear term in a linear equation, so that the original linear algorithm can be subjected to nonlinear regression, and nonlinear regression can be performed. Meanwhile, the kernel function is introduced, so that the purpose of dimension increasing is achieved, and overfitting can be controlled when adjustable parameters are added.
In practical application, the trained check valve wear state evaluation model is used for monitoring the check valve wear state on line, so that whether the check valve of the current injection molding machine is worn or not can be determined, and the wear of the current check valve in which grade can be accurately estimated.
In this embodiment, the wear state of the non-return valve is determined, specifically: setting different levels of abrasion state threshold values, outputting the abrasion degree of the check valve by the trained check valve abrasion state evaluation model, and determining the abrasion state of the check valve according to the abrasion degree of the check valve and the different levels of abrasion state threshold values.
The above embodiments are preferred embodiments of the present invention, but the present invention is not limited to the above embodiments, and any other changes, modifications, substitutions, combinations, and simplifications which do not depart from the spirit and principle of the present invention should be construed as equivalents thereof, and all such changes, modifications, substitutions, combinations, and simplifications are intended to be included in the scope of the present invention.