Printing machine material belt off-plane vibration transmission tension recognition method

Abstract

The invention relates to a method for identifying off-plane vibration transmission tension of a material belt of a printing machine. The method comprises the following steps: firstly, detecting normal vibration displacement of a material belt near a support roller in real time, and carrying out discretization modeling on a transmission system; then, fusing vibration data of the transmission system and the material belt, and constructing a comprehensive vibration data structure; a dynamic load and bending moment fitting function is constructed by extracting first-order symmetric and antisymmetric transverse resonant frequencies, and the dimensionless ratio of the average tension of the material belt and the tension change in a short time is calculated so as to identify the tension of the material belt at a monitoring point. And finally, carrying out tension transverse reconstruction by utilizing multi-point measurement, and displaying tension distribution. Longitudinal fluctuation of conveying tension of the material belt caused by vibration of the material belt away from the plane is accurately recognized, a tension control system of the printing machine can conveniently adjust tension change of a conveying system, the problems of material belt longitudinal deformation and printing deformation caused by too large tension or material belt wrinkling, printing blurring and the like caused by material belt transverse deformation are prevented, and the printing quality is improved. And the printing quality of the printing equipment is ensured.

Description

Technical Field

[0001] The invention belongs to the technical field of tension identification, and relates to a method for identifying the off-plane vibration transmission tension of a printing machine material belt. Technical Background

[0002] With the rapid development of science and technology, equipment manufacturing is developing towards high precision, and vigorously improving equipment production accuracy has become an important development direction of equipment manufacturing. Printing equipment has developed rapidly as a high-precision large-scale light industrial manufacturing equipment. However, the tension fluctuation of the printing tape during transmission will affect the quality of the printed product, and excessive tension fluctuation will cause printing deformation, blurring and printing wrinkles. The detection and control of the transmission tension fluctuation of the printing tape has become one of the key indicators for evaluating the performance of printing equipment.

[0003] During the operation of the printing press, the large-span material belt transmission system of the printing unit is responsible for the transmission of the printed object; under the action of the driving force, there is transmission tension in the material belt between the supporting rollers. As the material belt is transmitted, the unstable operation of the rollers and the air around the material belt will cause off-plane normal vibration, causing fluctuations in the material belt tension. Since the material belt is transported unidirectionally in the printing press, the material belt tension cannot be directly measured, so how to measure or identify the material belt transmission tension has become a key technology to improve the performance of printing equipment.

[0004] It should be noted that this section is intended to provide a background or context to embodiments of the invention recited in the claims. No admission is made that the description herein is prior art by inclusion in this section. Summary of the invention

[0005] The purpose of the present invention is to provide a method for identifying the transmission tension of the material belt of a printing machine due to the off-plane vibration of the material belt, accurately identifying the longitudinal fluctuation of the material belt transmission tension caused by the off-plane vibration of the material belt, facilitating the tension control system of the printing machine to adjust the tension change of the transmission system, preventing the longitudinal deformation of the material belt and printing deformation caused by excessive tension, or the lateral deformation of the material belt causing material belt wrinkles and blurred printing, and ensuring that the printing equipment accurately adjusts the printing pressure and printing quality.

[0006] To achieve the above purpose, the present invention adopts the following technical solutions:

[0007] The method for identifying the off-plane vibration transmission tension of a printing press material belt comprises the following steps:

[0008] S1: Collection of vibration signals of the transmission material belt off the plane near the supporting roller;

[0009] S2: off-plane vibration signal data structure model;

[0010] S3: Extraction of strip vibration displacement features;

[0011] S4: Discrete-time tension fluctuation model construction;

[0012] S5: lateral reconstruction of strip tension identification.

[0013] Furthermore, the above step S1 specifically includes:

[0014] Collect the off-plane vibration displacement response data of the material belt near the large-span support during the material belt transmission process.

[0015] Furthermore, the measurement of the out-of-plane vibration displacement of the material belt refers to the measurement of the normal vibration displacement of the perpendicular material belt transmission plane; the vibration displacement measurement is a non-contact measurement to avoid the influence of the contact of the data acquisition equipment on the measurement results; the out-of-plane vibration measurement position of the material belt is 15cm-20cm away from the large-span support end; the out-of-plane vibration measurement of the material belt includes at least three points: the two lateral free edges of the material belt and the lateral center of the material belt.

[0016] Furthermore, the above step S2 specifically includes:

[0017] The construction of the data structure model of the material belt off-plane vibration signal includes the discrete modeling of the printing press material belt transmission system and the construction of the time discretization model of the off-plane vibration model;

[0018] S201: Discrete modeling of the printing press material transmission system:

[0019] Partial differential equation of motion for tension out-of-plane vibration:

[0020]

[0021] In the formula, ρ w is the area mass density of the strip, w(x1,x3,t) is the lateral deflection of the strip, x1 is the displacement along the length of the strip, x2 is the displacement along the normal direction of the strip, x3 is the displacement along the width direction of the strip, t is the time, Bending stiffness of the strip, E is the Young's modulus of the strip, h is the thickness of the strip, and p is the Poisson's ratio of the strip material; is a biharmonic operator, N(x3) is the uniaxial tensile tension per unit width, and P(x1,x3,t) is the transverse air pressure on the surface of the strip.

[0022] The vibration response transfer function of the material belt transmission system is calculated based on the partial differential equation of motion of the tension off-plane vibration:

[0023]

[0024] Where, H is the system transfer function matrix, h 1…n Discretized structural vibration response transfer function for the material belt transmission system;

[0025] S202: constructing a time discretization model of the off-plane vibration signal; dividing the off-plane vibration signal into a number of data packets, with a time interval of Δt between the data packets; within the data time period required for tension identification, the product of the number of data packets and the pulse width Δt is a constant, and the discrete form can be expressed as:

[0026]

[0027] Where D 1…n is the discretized structural vibration response of the belt transmission system; h 1…n is the transfer function matrix of the discretized structural vibration response of the material belt transmission system; It is the driving force of the air around the strip; is the driving force of the supporting roller; Δt is the time width.

[0028] Furthermore, the above step S3 specifically includes:

[0029] The first-order symmetric transverse resonance frequency and the first-order antisymmetric transverse resonance frequency of the strip transmission vibration displacement are extracted, and the calculation formula is as follows:

[0030]

[0031] Among them, f 11...1N is the first-order symmetrical transverse resonance frequency, p 11…NN is the first-order symmetrical transverse resonance frequency conversion factor

[0032]

[0033] Among them, f 21…2N is the first-order antisymmetric transverse resonance frequency, q 11…NN is the first-order antisymmetric transverse resonance frequency conversion factor.

[0034] Furthermore, the above step S4 specifically includes:

[0035] The sixth-order dynamic load fitting function of the transmission belt F1, F2, F3, F4, F5, F6 is expressed as follows;

[0036]

[0037] In the formula, v is the material belt transmission speed, b is the material belt width, and L is the span of the material belt in the transport direction.

[0038] The two-dimensional bending moment fitting function of the transmission belt, and The expression is:

[0039]

[0040]

[0041] Where: w is the strip area mass density, ρ a is the mixed gas density on the strip surface.

[0042] Δt Average tension of inner strip N a and relative to N a The dimensionless ratio σ of the linear variation of maximum and minimum tension is expressed as:

[0043]

[0044] Wherein, f1 is the first-order symmetric transverse resonance frequency vector, and f2 is the first-order antisymmetric transverse resonance frequency. Further, the above step S5 is specifically:

[0045] The strip tension identification and lateral reconstruction, the strip tension calculated in step S4 is the single-point off-plane strip tension identification, the strip tension identification requires at least three points of measurement to identify the lateral bending deformation, causing the strip wrinkles, and the strip tension lateral reconstruction can be achieved through multi-point measurement, the expression is as follows:

[0046] P=[N1(x3)…N i (x3)…N I (x3)] (17)

[0047] Where P is the tension transverse reconstruction vector, and I is the number of non-contact off-plane vibration measurement points.

[0048] Beneficial effects of the present invention:

[0049] (1) The discretization modeling of the large-span material belt transmission system of the pin printer of the present invention discretizes the vibration response and transfer function, and comprehensively characterizes the dynamic characteristics of the material belt transmission system of the printer;

[0050] (2) The present invention integrates the printing press material belt transmission system and the material belt off-plane normal vibration data to form a comprehensive printing press material belt transmission system vibration data structure.

[0051] (3) The present invention extracts the resonant frequency of the material strip, calculates the average tension of the material strip and the tension fluctuation ratio, and accurately identifies the transmission tension of the material strip.

[0052] (4) The present invention adopts a multi-point lateral acquisition and multi-point tension identification method to achieve lateral reconstruction of printing tension and precisely display the lateral change gradient of printing tension.

[0053] (5) The present invention accurately identifies the longitudinal fluctuation of the material belt transmission tension caused by the off-plane vibration of the material belt, which facilitates the tension control system of the printing press to adjust the tension change of the transmission system, prevents the longitudinal deformation of the material belt and printing deformation caused by excessive tension, or the lateral deformation of the material belt causing material belt wrinkles and blurred printing, thereby ensuring the printing quality of the printing equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0054] Figure 1 It is a process framework diagram of the present invention;

[0055] Figure 2 It is a flow chart of the implementation steps of the present invention; DETAILED DESCRIPTION

[0056] Example embodiments will now be described more fully with reference to the accompanying drawings. However, example embodiments can be implemented in a variety of forms and should not be construed as limited to the examples set forth herein; rather, these embodiments are provided so that the present invention will be more comprehensive and complete and fully convey the concepts of the example embodiments to those skilled in the art. The described features or characteristics may be combined in any suitable manner in one or more embodiments.

[0057] The present invention is described in detail with reference to the accompanying drawings, and the specific steps are as follows:

[0058] See also Figure 1 , Figure 2 The method for identifying the transmission tension of an off-plane vibrating material belt described in the present invention includes five parts: collecting the off-plane vibration signal of the transmission material belt, a data structure model of the off-plane vibration signal, extracting the vibration displacement characteristics of the material belt, constructing a discrete time tension fluctuation model, and lateral reconstruction of the material belt tension identification.

[0059] The off-plane vibration signal of the printing press transmission belt is collected, and the normal vibration displacement near the belt support is collected when the printing press is running; the off-plane vibration signal data structure model is the discretization modeling of the printing press belt transmission system and the vibration signal model of the belt normal plane vibration response; the belt vibration displacement feature is extracted by using the first-order symmetric lateral resonance frequency conversion matrix and the first-order antisymmetric lateral resonance frequency conversion matrix to extract the first-order symmetric lateral resonance frequency and the first-order antisymmetric lateral resonance frequency from the vibration signal; the discrete-time tension fluctuation model is constructed, and the actual belt transmission tension is calculated by using the multiple average tensions and tension fluctuation ratios of the test point tension; the lateral reconstruction of the belt tension identification is achieved by multi-point identification of the lateral multi-point vibration collection of the belt, and the lateral change gradient of the belt tension is displayed.

[0060] Among them, the collection of the out-of-plane vibration displacement of the material belt refers to the collection of the normal vibration displacement of the perpendicular material belt transmission plane; the vibration displacement measurement is a non-contact measurement to avoid the influence of the contact of the data acquisition equipment on the measurement results; the out-of-plane vibration measurement position of the material belt is 15cm-20cm away from the large-span support end; the out-of-plane vibration measurement of the material belt includes at least three points: the two free edges of the material belt and the lateral center of the material belt. The data sampling rate should be greater than 5000, and the number of data packets should be 5 times the number of identified tensions per unit time; in order to accurately display the lateral change gradient of the material belt tension, the number of detection points should be no less than 6.

[0061] The transmission tension calculation of the printing press belt includes the calculation of the sixth-order dynamic load fitting function of the transmission belt, the two-dimensional bending moment fitting calculation of the transmission belt, the average equivalent tension calculation, the tension fluctuation ratio calculation and the comprehensive tension calculation.

[0062] Specific facts of the method for identifying the off-plane vibration transmission tension of a printing press belt proposed by the present invention:

[0063] During the operation of the printing machine, the large-span material belt transmission system of the printing unit is responsible for the transmission of the printed object; under the action of the driving force, there is a transmission tension between the supporting rollers. As the material belt is transmitted, the unstable operation of the rollers and the air around the material belt will cause off-plane normal vibration, causing the material belt tension to fluctuate. Excessive tension fluctuations will cause printing deformation, blurring, printing wrinkles and other phenomena. The method for identifying the off-plane vibration transmission tension of the printing press material belt proposed in the present invention detects the normal vibration displacement of the material belt near the supporting roller in real time, and discretizes the printing press material belt transmission system to model the vibration response and transfer function, and comprehensively characterizes the dynamic characteristics of the printing press material belt transmission system; further, the printing press material belt transmission system and the off-plane normal vibration data of the material belt are integrated to form a comprehensive vibration data structure of the printing press material belt transmission system; at the same time, the first-order symmetric transverse resonance frequency and the first-order antisymmetric transverse resonance frequency are extracted; according to the printing press material belt transmission system, discretization modeling is performed to construct the sixth-order dynamic load fitting functions F1, F2, F3, F4, F5, F6 of the transmission material belt and the two-dimensional bending moment fitting M1 and M2 of the transmission material belt, and the average tension N of the material belt within Δt is calculated. a and relative to N a The dimensionless ratio σ of the linear change of the maximum and minimum tensions is used to identify the tension of the material strip at the monitoring point. Finally, through multi-point measurement, the lateral reconstruction of the material strip tension is carried out to display the lateral distribution of the tension and realize the accurate identification of the material strip tension.

[0064] The method for identifying the vibration transmission tension of the printing press belt off the plane is mainly achieved through the following steps:

[0065] Step 1: Collect the off-plane vibration displacement response data of the material belt near the large-span support during the material belt transmission process.

[0066] Furthermore, the measurement of the out-of-plane vibration displacement of the material belt refers to the measurement of the normal vibration displacement of the perpendicular material belt transmission plane; the vibration displacement measurement is a non-contact measurement to avoid the influence of the contact of the data acquisition equipment on the measurement results; the out-of-plane vibration measurement position of the material belt is 15cm-20cm away from the large-span support end; the out-of-plane vibration measurement of the material belt includes at least three points: the two lateral free edges of the material belt and the lateral center of the material belt.

[0067] Step 2: Discrete modeling of the printing press material transmission system

[0068] Partial differential equation of motion for tension out-of-plane vibration:

[0069]

[0070] In the formula, ρ w is the area mass density of the strip, w(x1,x3,t) is the lateral deflection of the strip, x1 is the displacement along the length of the strip, x2 is the displacement along the normal direction of the strip, x3 is the displacement along the width direction of the strip, t is the time, Bending stiffness of the strip, E is the Young's modulus of the strip, h is the thickness of the strip, and p is the Poisson's ratio of the strip; is a biharmonic operator, N(x3) is the uniaxial tensile tension per unit width, and P(x1,x3,t) is the transverse air pressure on the surface of the strip.

[0071] The vibration response transfer function of the material belt transmission system is calculated based on the partial differential equation of motion of the tension off-plane vibration:

[0072]

[0073] Where, H is the system transfer function matrix, h 1…n Discretized structural vibration response transfer function for the material belt transmission system;

[0074] Step 3: Discretization of the off-plane vibration signal. The off-plane vibration signal is divided into several data packets with a time interval of Δt. In the data time period required for tension identification, the product of the number of data packets and the pulse width Δt is a constant, and the discrete form can be expressed as:

[0075]

[0076] Where D 1…n is the discretized structural vibration response of the belt transmission system; h 1…n is the discretized structural vibration response transfer function matrix of the material belt transmission system; It is the driving force of the air around the strip; is the driving force of the supporting roller; Δt is the time width

[0077] Step 4: Extract the first-order symmetric transverse resonance frequency and the first-order antisymmetric transverse resonance frequency of the strip transmission vibration displacement. The calculation formula is as follows:

[0078]

[0079] Among them, f 11…1N is the first-order symmetrical transverse resonance frequency, p 11...NN is the first-order symmetrical transverse resonance frequency conversion factor

[0080]

[0081] Among them, f 21...2N is the first-order antisymmetric transverse resonance frequency, q 11…NN is the first-order antisymmetric transverse resonance frequency conversion factor.

[0082] Step 5: Construct the sixth-order dynamic load fitting functions F1, F2, F3, F4, F5, and F6 of the transmission belt;

[0083]

[0084] In the formula, v is the transmission speed of the tape, b is the width of the tape, and L is the width length of the tape.

[0085] Step 6: 2D bending moment fitting function of the transmission strip and

[0086]

[0087] Where: w is the strip area mass density, ρ a is the mixed gas density on the surface of the material belt, and L is the span of the material belt in the transport direction.

[0088] Step 7: Average tension N of the strip within Δt a and relative to N a The dimensionless ratio σ of the linear variation of maximum and minimum tension is calculated as:

[0089]

[0090]

[0091] Step 8: Discrete-time tension fluctuation model construction. By solving equation (1), the tension calculation equation can be obtained as follows:

[0092]

[0093] Where: N a is the average tension of the strip within Δt, σ is relative to Na The dimensionless ratio of the maximum to minimum tension changes linearly, where b is the width of the strip.

[0094] Step 9: lateral reconstruction of material strip tension identification. The material strip tension calculated in step S4 is a single-point off-plane material strip tension identification. Material strip tension identification requires at least three-point measurement to identify lateral bending deformation, which causes material strip wrinkles. Multi-point measurement can achieve lateral reconstruction of material strip tension. The expression is as follows:

[0095] P=[N1(x3)...N i (x3)…N I (x3)] (17)

[0096] Where P is the tension transverse reconstruction vector, and I is the number of non-contact off-plane vibration measurement points.

[0097] The present invention can be obtained through steps (1) to (9).

[0098] Identification of the off-plane vibration transmission tension of the printing press material belt. If there is a deviation, the recognition accuracy can be improved by changing the average number of vibration responses in step (3); revising the first-order symmetric transverse resonance frequency and the first-order antisymmetric transverse resonance frequency. Similarly, the recognition performance can be adjusted by revising the constant coefficients in steps (5) and (6).

[0099] Those skilled in the art will readily appreciate other embodiments of the present invention after considering the specification and practicing the invention disclosed herein. This application is intended to cover any variations, uses or adaptations of the present invention, which follow the general principles of the present invention and include common knowledge or customary techniques in the art that are not disclosed by the present invention. The specification and examples are intended to be exemplary only, and the true scope and spirit of the present invention are indicated by the appended claims.

Claims

1. A method for identifying the off-plane vibration transmission tension of a printing press belt, characterized in that: The following steps are involved: S1: Collection of vibration signals of the conveying material from the plane; S2: off-plane vibration signal data structure model; S3: Extraction of strip vibration displacement features; S4: Discrete-time tension fluctuation model construction; S5: lateral reconstruction of strip tension identification.

2. The method for identifying the off-plane vibration transmission tension of a printing press material belt according to claim 1, characterized in that: The step S1 specifically comprises: The measurement of the out-of-plane vibration displacement of the material belt is to measure the normal vibration displacement of the perpendicular material belt transmission plane; the vibration displacement measurement is a non-contact measurement to avoid the influence of the contact of the data acquisition equipment on the measurement results; the out-of-plane vibration measurement position of the material belt is 15cm-20cm away from the large-span support end; the out-of-plane vibration measurement of the material belt includes at least three points: the two free edges of the material belt and the lateral center of the material belt.

3. The method for identifying the off-plane vibration transmission tension of a printing press material belt according to claim 1, characterized in that: The step S2 specifically comprises: The construction of the data structure model of the material belt off-plane vibration signal includes the discrete modeling of the printing press material belt transmission system and the construction of the time discretization model of the off-plane vibration model; S201: Discrete modeling of the printing press belt transmission system: Partial differential equation of motion for tension out-of-plane vibration: In the formula, ρ w is the area mass density of the strip, w(x1,x3,t) is the lateral deflection of the strip, x1 is the displacement along the length of the strip, x2 is the displacement along the normal direction of the strip, x3 is the displacement along the width direction of the strip, t is the time, Bending stiffness of the strip, E is the Young's modulus of the strip, h is the thickness of the strip, and ρ is the Poisson's ratio of the strip material; ▽ 4 is a biharmonic operator, N(x3) is the uniaxial tensile force per unit width, P(x1,x3,t) is the horizontal air pressure on the strip surface; The vibration response transfer function of the material belt transmission system is calculated based on the partial differential equation of motion of the tension off-plane vibration: Where, H is the system transfer function matrix, h 1…n Discretized structural vibration response transfer function for the material belt transmission system; S202: constructing a time discretization model of the off-plane vibration signal; dividing the off-plane vibration signal into a number of data packets, with a time interval of Δt between the data packets; within the data time period required for tension identification, the product of the number of data packets and the pulse width Δt is a constant, and the discrete form can be expressed as: Where D 1...n is the discretized structural vibration response of the belt transmission system; h 1...n is the discretized structural vibration response transfer function matrix of the material belt transmission system; It is the driving force of the air around the strip; is the driving force of the supporting roller; Δt is the time width.

4. The method for identifying the off-plane vibration transmission tension of a printing press material belt according to claim 1, characterized in that: The step S3 specifically comprises: The first-order symmetric transverse resonance frequency and the first-order antisymmetric transverse resonance frequency of the strip transmission vibration displacement are extracted, and the calculation formula is as follows: Among them, f 11...1N is the first-order symmetrical transverse resonance frequency, p 11...NN is the first-order symmetrical transverse resonance frequency conversion factor Among them, f 21...2N is the first-order antisymmetric transverse resonance frequency, q 11…NN is the first-order antisymmetric transverse resonance frequency conversion factor.

5. The method for identifying the off-plane vibration transmission tension of a printing press material belt according to claim 1, characterized in that: The step S4 specifically comprises: S401: calculation of the sixth-order dynamic load fitting functions F1, F2, F3, F4, F5, and F6 of the transmission belt; In the formula, L is the span of the supporting roller of the transmission belt, and b is the width of the belt; S402: Two-dimensional bending moment fitting function of transmission belt and In the formula, ρ a is the density of the mixed gas around the strip S403: Average tension of the strip in Δt N a and relative to N a The dimensionless ratio σ of the linear variation of maximum and minimum tension is calculated as: S404: discrete time tension fluctuation model is constructed. By solving equation (1), the tension calculation equation can be obtained as follows: Where: N a is the average tension of the strip within Δt, σ is relative to N1 a 1 is the dimensionless ratio of the maximum to minimum tension linear variation, b is the width of the strip.

6. The method for identifying the off-plane vibration transmission tension of a printing press material belt according to claim 1, characterized in that: The step S5 specifically comprises: The strip tension identification and lateral reconstruction require at least three-point measurement to identify the lateral bending deformation that causes the strip wrinkles. The lateral reconstruction of the strip tension can be achieved through multi-point measurement. The expression is as follows: P=[N1(x3)…N i (x3)…N I (x3)] (17) Where P is the tension transverse reconstruction vector, and I is the number of non-contact off-plane vibration measurement points.

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