Fault diagnosis method and system for weft knitting machines based on triangular vibration response characteristics

Abstract

The present invention discloses a fault diagnosis method and system for a weft knitting machine based on the vibration response characteristics of a triangle, belonging to the fields of data processing and textile knitting technology. The method comprises: obtaining a vibration signal of the weaving roller triangle by setting a piezoelectric ceramic on the surface of the weaving roller triangle; analyzing the vibration frequency and vibration amplitude of the weaving roller triangle based on the vibration signal of the weaving roller triangle; obtaining a needle selection frequency under a preset needle method; determining whether the weft knitting machine has a fault under the preset needle method based on the needle selection frequency and the vibration frequency of the weaving roller triangle; obtaining a needle cylinder speed; and determining whether the weft knitting machine has a fault based on the needle cylinder speed and the vibration amplitude of the weaving roller triangle. There is no need to rely on professional maintenance personnel for on-site diagnosis, the diagnostic delay is low, and efficient and real-time fault detection can be achieved. It is not affected by changes in the actuator and is applicable to various types of needle cylinders, knitting needles, and weaving roller triangles. The automated detection has strong versatility and high fault diagnosis accuracy.

Description

Technical Field

[0001] The invention belongs to the technical field of data processing and textile knitting, and particularly relates to a fault diagnosis method and system for a weft knitting machine based on triangular vibration response characteristics. Background Art

[0002] A weft knitting machine is a specialized textile equipment that uses the interaction between needles and cams to complete processes such as unwinding, yarn padding, yarn bending, and loop formation. Improving the self-sensing capability of the weft knitting machine's operating status and its self-diagnosis capability for faults is a key research topic within the industry.

[0003] However, weft knitting machines are prone to failure due to the complexity of their operating environment and wear of their mechanical components. Traditional fault diagnosis methods suffer from diagnostic delays and low accuracy, and rely primarily on on-site diagnosis by professional maintenance personnel, failing to meet the needs of efficient and real-time fault detection.

[0004] Some studies have used electromagnetic needle selectors as research objects. By detecting the changes in current during the on-off process of the electromagnetic coil and the swing pattern of the cutter head, the self-diagnosis of electromagnetic needle selector short circuit, open circuit and abnormal cutter head faults is realized. Although the self-sensing and fault self-diagnosis capabilities of weft knitting equipment have been improved to a certain extent, the research mainly focuses on a single type of actuator (needle selection actuator, yarn detection actuator, density adjustment actuator, etc.), which has poor versatility. When the type and parameters of the actuator change (such as the use of piezoelectric needle selectors instead of electromagnetic needle selectors in weft knitting machines), the detection method needs to be re-studied and debugged. Even if the detection results of each actuator are normal, it cannot guarantee the accuracy of the needle output method, the terminal control link of the weft knitting needle machine. Therefore, improving the performance of weft knitting machines from the level of a single actuator still has great limitations. Summary of the Invention

[0005] In order to solve the technical problems in the prior art that traditional fault diagnosis methods have diagnostic delays and low accuracy, mainly rely on professional maintenance personnel for on-site diagnosis, cannot meet the needs of efficient and real-time fault detection, have poor versatility in automated detection of single actuators, and have low fault diagnosis accuracy, the present invention provides a weft knitting machine fault diagnosis method and system based on triangular vibration response characteristics.

[0006] First aspect

[0007] The present invention provides a fault diagnosis method for a weft knitting machine based on the vibration response characteristics of a triangle. The weft knitting machine includes a needle cylinder, a knitting needle, and a knitting roller triangle. The knitting needle is arranged on a notch of the needle cylinder. The weft knitting machine completes knitting work through the interaction between the knitting needle and the knitting roller triangle. The fault diagnosis method for the weft knitting machine includes:

[0008] S101: obtaining a vibration signal of the weaving roller triangle by setting a piezoelectric ceramic on the surface of the weaving roller triangle;

[0009] S102: Analyzing the vibration frequency and amplitude of the weaving roller cam according to the vibration signal of the weaving roller cam;

[0010] S103: Obtaining the needle selection frequency under the preset needle method;

[0011] S104: determining whether the weft knitting machine has a fault under a preset needle method according to the needle selection frequency and the vibration frequency of the weaving roller cam;

[0012] S105: Obtaining the syringe rotation speed;

[0013] S106: Determine whether the weft knitting machine has a fault based on the needle cylinder speed and the vibration amplitude of the weaving roller triangle.

[0014] Second aspect

[0015] The present invention provides a weft knitting machine fault diagnosis system based on triangular vibration response characteristics, which is used to execute the weft knitting machine fault diagnosis method based on triangular vibration response characteristics in the first aspect.

[0016] Compared with the prior art, the present invention has at least the following beneficial technical effects:

[0017] The present invention automatically monitors weft knitting machine faults by attaching piezoelectric ceramics to the surface of the weaving roller cam to detect its vibration signal. This system eliminates the need for on-site diagnosis by specialized maintenance personnel, offers low diagnostic latency, and enables efficient, real-time fault detection. This system is unaffected by actuator changes and is applicable to various types of needle cylinders, knitting needles, and weaving roller cams. The automated detection system offers high versatility and diagnostic accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The preferred embodiments will be described below in a clear and understandable manner with reference to the accompanying drawings to further illustrate the above-mentioned characteristics, technical features, advantages and implementation methods of the present invention.

[0019] Figure 1 1 is a flow chart of a method for diagnosing a fault of a weft knitting machine based on triangular vibration response characteristics provided by the present invention;

[0020] Figure 2 It is a schematic diagram of the forced movement of a knitting needle along a knitting roller triangle during a knitting process provided by the present invention. DETAILED DESCRIPTION

[0021] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the specific embodiments of the present invention will be described below with reference to the accompanying drawings. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings and other embodiments can be obtained based on these drawings without inventive work.

[0022] To simplify the drawings, only portions relevant to the invention are schematically depicted in each figure; they do not represent the actual structure of the product. Furthermore, to simplify the drawings and facilitate understanding, in some figures, only one component with the same structure or function is schematically depicted or labeled. In this document, "one" not only means "only one" but also "more than one."

[0023] It should be further understood that the term "and / or" used in the present description and the appended claims refers to and includes any and all possible combinations of one or more of the associated listed items.

[0024] It should be noted that, unless otherwise specified or limited, the terms "mounted," "connected," and "connected" should be understood broadly. For example, they can refer to fixed connections, removable connections, or integral connections. They can also refer to mechanical connections or electrical connections. They can also refer to direct connections or indirect connections through an intermediary, or to internal communication between two components. Those skilled in the art will understand the specific meanings of these terms in the present invention based on the specific circumstances.

[0025] In addition, in the description of the present invention, the terms "first", "second", etc. are only used to distinguish the description and cannot be understood as indicating or implying relative importance.

[0026] Example 1

[0027] In one embodiment, the reference Figure 1 , which shows a flow chart of a fault diagnosis method for a weft knitting machine based on triangular vibration response characteristics provided by the present invention.

[0028] The weft knitting machine includes a needle cylinder, knitting needles and a knitting roller cam. The knitting needles are arranged on the notches of the needle cylinder. The weft knitting machine completes the knitting work through the interaction between the knitting needles and the knitting roller cam.

[0029] Reference Manual Figure 2 , showing a schematic diagram of the forced movement of the knitting needle along the weaving roller triangle during a weaving process provided by the present invention.

[0030] The needle trajectory of the weft knitting mechanism is mainly determined by the needle selector head movement and the working state of the triangle, thereby forming various weft knitted fabrics. The needles are embedded in the left and right side walls of the needle cylinder and move in a circular motion with the needle cylinder. Figure 2 As shown in the figure, according to the actual needle selection process of the weft knitting machine, when the needle selector head acts on the jacquard piece needle butt, the jacquard piece is pressed into the inner wall of the needle groove, and the knitting needle follows the buried needle trajectory, otherwise it walks out of the needle trajectory. Under the needle exit trajectory, before the knitting needle hits the triangle, the knitting needle moves horizontally at a speed of V1. After hitting the triangle, it continues to move along the inclined plane at a speed of V2 and causes the triangle to vibrate attenuated in all directions. Therefore, different needle exit methods and needle cylinder speeds will affect the vibration response characteristics of the triangle.

[0031] The present invention provides a weft knitting machine fault diagnosis method based on triangular vibration response characteristics, comprising:

[0032] S101: Acquire a vibration signal of the weaving roller triangle by setting a piezoelectric ceramic on the surface of the weaving roller triangle.

[0033] Among them, piezoelectric ceramics have a good piezoelectric effect. The piezoelectric effect refers to the phenomenon that piezoelectric ceramic materials produce charge separation or potential difference when mechanical stress or electric field is applied, and vice versa.

[0034] It should be noted that when the weaving roller cam vibrates, a mechanical force or pressure acts on the piezoelectric ceramic. Due to the piezoelectric effect, this mechanical force causes the piezoelectric ceramic to generate an electric charge. By converting this charge signal into a voltage signal, the vibration signal of the weaving roller cam can be measured and recorded.

[0035] Specifically, the piezoelectric ceramic may be PZT (Lead Zirconate Titanate).

[0036] Optionally, the PZT rectangular sheet is attached to the upper surface of the lowering needle triangle through a thin layer of adhesive, and the two wires are spot-welded to the upper surface of the PZT rectangular sheet and the upper surface of the lowering needle triangle through welding points.

[0037] S102: Analyze the vibration frequency and amplitude of the weaving roller cam according to the vibration signal of the weaving roller cam.

[0038] Specifically, the Fast Fourier Transform (FFT) algorithm converts the time-domain signal into the frequency domain, decomposing the vibration signal into components of varying frequencies. Analyzing the spectrum determines the primary frequency components of the vibration signal and their corresponding amplitudes. The dominant frequency peaks correspond to the primary frequency components of the vibration, while the height of the peaks indicates the amplitude of the vibration.

[0039] In a possible implementation, the vibration frequency of the weaving roller cam is less than a preset frequency.

[0040] Optionally, the preset frequency is 5Khz.

[0041] During the research process of this invention, it was found that at the moment the knitting needle hits the loom roller cam, the amplitude of the vibration electrical signal reaches its maximum value in a relatively short time (negligible compared to the needle selector cycle), and then gradually decays to 0. The decay time period is roughly consistent, all around 200us, and has nothing to do with the impact speed. Therefore, theoretically, based on the vibration attenuation characteristics of the "camera + PZT" coupling body, fault detection can be achieved at an impact frequency within 5Khz. Therefore, the vibration frequency of the loom roller cam is less than the preset frequency of 5Khz. In other words, the accuracy of the fault detection result can only be guaranteed when the vibration frequency of the loom roller cam is less than 5Khz.

[0042] S103: Acquire the needle selection frequency under the preset needle method.

[0043] The needle selection frequency refers to the frequency at which the needles in a weft knitting machine move up and down. It represents the number of needle selections per minute and is usually expressed as stitches per minute (SPM). The needle selection frequency has a significant impact on the efficiency of the weft knitting machine and the structural properties of the fabric. A higher needle selection frequency allows for faster weaving speeds, but it also affects the quality and stability of the fabric. Therefore, in the weft knitting process, an appropriate needle selection frequency must be selected based on the specific weaving requirements and fabric characteristics.

[0044] S104: Determine whether the weft knitting machine has a fault under a preset needle method according to the needle selection frequency and the vibration frequency of the weaving roller cam.

[0045] Specifically, there is a correlation between the needle selection frequency and the vibration frequency of the weaving roller cam. If at a certain moment, the needle selection frequency and the vibration frequency of the weaving roller cam deviate from the correlation, it can be determined that the weft knitting machine has a fault.

[0046] Furthermore, the applicant discovered during the research process that when the knitting needles make n1×n2 stitches, the needle selection frequency is n1+n2 times the vibration frequency of the knitting roller triangle.

[0047] In a possible implementation, S104 specifically includes sub-steps S1041 and S1042:

[0048] S1041: When the needle selection frequency and the vibration frequency of the weaving roller cam satisfy a first preset correlation relationship, it is determined that the weft knitting machine has no fault.

[0049] In a possible implementation, the relationship equation corresponding to the first preset association relationship is:

[0050]

[0051] Among them, f represents the vibration frequency of the weaving roller triangle, F represents the needle selection frequency under the n1×n2 needle method, and n1 and n2 represent the combined integer variables of the needle output method.

[0052] S1042: When the needle selection frequency and the vibration frequency of the weaving roller cam do not satisfy a first preset correlation relationship, it is determined that the weft knitting machine has a fault.

[0053] The fault types at this time may be weaving roller triangle failure, needle selection system failure, control system failure, transmission system problem, looseness or wear of mechanical connectors, etc.

[0054] S105: Obtain the syringe rotation speed.

[0055] Needle cylinder speed refers to the speed at which the needle cylinder in a weft knitting machine rotates. It is a crucial parameter for the machine's operation and control. The speed directly impacts the production speed and quality of knitted fabrics. Needle cylinder speed is typically expressed in revolutions per minute (RPM), representing the number of revolutions per minute. Needle cylinder speed is controlled by the machine's main drive system, typically via a motor and transmission.

[0056] S106: Determine whether the weft knitting machine has a fault based on the needle cylinder speed and the vibration amplitude of the weaving roller triangle.

[0057] Specifically, there is a correlation between the needle cylinder speed and the vibration amplitude of the weaving roller triangle. If at a certain moment, the needle cylinder speed and the vibration amplitude of the weaving roller triangle deviate from the correlation, it can be determined that there is a fault in the weft knitting machine.

[0058] Furthermore, the applicant discovered during the research process that the vibration amplitude of the weaving roller triangle increases linearly with the rotation speed of the needle cylinder, and has nothing to do with the specific needle method.

[0059] In a possible implementation, S106 specifically includes sub-steps S1061 and S1062:

[0060] S1061: When the needle cylinder rotation speed and the vibration amplitude of the weaving roller triangle satisfy a second preset correlation relationship, it is determined that the weft knitting machine has no fault.

[0061] S1062: When the needle cylinder rotation speed and the vibration amplitude of the weaving roller cam do not satisfy a second preset correlation relationship, it is determined that the weft knitting machine has a fault.

[0062] The fault types at this time may be weaving roller triangle failure, needle cylinder system failure, control system failure, transmission system problem, etc.

[0063] By monitoring the relationship between the needle cylinder speed and the vibration amplitude of the weaving roller triangle, the hysteresis and stability of the weaving speed of the weft knitting machine can be detected online.

[0064] In a possible implementation, the relationship equation corresponding to the second preset association relationship is:

[0065] y=kx+b

[0066] Among them, x represents the needle cylinder speed, y represents the vibration amplitude of the weaving roller triangle, k represents the slope, and b represents the intercept.

[0067] That is to say, the vibration amplitude of the weaving roller triangle is linearly related to the needle cylinder speed.

[0068] In a possible implementation, in the relationship formula corresponding to the second preset association relationship, k=0.00512, b=0.04893.

[0069] Compared with the prior art, the present invention has at least the following beneficial technical effects:

[0070] The present invention automatically monitors weft knitting machine faults by attaching piezoelectric ceramics to the surface of the weaving roller cam to detect its vibration signal. This system eliminates the need for on-site diagnosis by specialized maintenance personnel, offers low diagnostic latency, and enables efficient, real-time fault detection. This system is unaffected by actuator changes and is applicable to various types of needle cylinders, knitting needles, and weaving roller cams. The automated detection system offers high versatility and diagnostic accuracy.

[0071] Example 2

[0072] In one embodiment, the present invention provides a weft knitting machine fault diagnosis system based on triangular vibration response characteristics, which is used to execute the weft knitting machine fault diagnosis method based on triangular vibration response characteristics in Example 1.

[0073] The present invention provides a weft knitting machine fault diagnosis system based on triangular vibration response characteristics, which can realize the steps and effects of the weft knitting machine fault diagnosis method based on triangular vibration response characteristics in the above-mentioned embodiment 1. To avoid repetition, the present invention will not elaborate on them.

[0074] Compared with the prior art, the present invention has at least the following beneficial technical effects:

[0075] The present invention automatically monitors weft knitting machine faults by attaching piezoelectric ceramics to the surface of the weaving roller cam to detect its vibration signal. This system eliminates the need for on-site diagnosis by specialized maintenance personnel, offers low diagnostic latency, and enables efficient, real-time fault detection. This system is unaffected by actuator changes and is applicable to various types of needle cylinders, knitting needles, and weaving roller cams. The automated detection system offers high versatility and diagnostic accuracy.

[0076] The technical features of the above embodiments can be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0077] The above embodiments merely illustrate several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent. It should be noted that a person skilled in the art would be able to make various modifications and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the patent for this invention shall be determined by the appended claims.

Claims

1. A fault diagnosis method for a weft knitting machine based on triangular vibration response characteristics, characterized in that: The weft knitting machine includes a needle cylinder, a knitting needle, and a knitting roller cam, wherein the knitting needle is arranged on a notch of the needle cylinder. The weft knitting machine completes knitting work through the interaction between the knitting needle and the knitting roller cam. The fault diagnosis method of the weft knitting machine includes: S101: obtaining a vibration signal of the weaving roller cam by disposing piezoelectric ceramics on the surface of the weaving roller cam; S102: Analyzing the vibration frequency and amplitude of the weaving roller cam according to the vibration signal of the weaving roller cam; S103: Obtaining the needle selection frequency under the preset needle method; S104: determining whether the weft knitting machine has a fault under the preset needle method according to the needle selection frequency and the vibration frequency of the weaving roller cam; S105: Obtaining the syringe rotation speed; S106: Determining whether the weft knitting machine has a fault based on the needle cylinder speed and the vibration amplitude of the weaving roller cam; The S104 specifically includes: S1041: When the needle selection frequency and the vibration frequency of the weaving roller cam satisfy a first preset correlation relationship, determining that the weft knitting machine has no fault; S1042: When the needle selection frequency and the vibration frequency of the weaving roller cam do not satisfy the first preset correlation relationship, determining that the weft knitting machine has a fault; The relationship formula corresponding to the first preset association relationship is: Among them, f represents the vibration frequency of the weaving roller triangle, F represents the needle selection frequency under the n1×n2 needle method, and n1 and n2 represent combined integer variables of the needle output method.

2. The fault diagnosis method for a weft knitting machine based on triangular vibration response characteristics according to claim 1, characterized in that: The S106 specifically includes: S1061: When the needle cylinder rotation speed and the vibration amplitude of the weaving roller cam satisfy a second preset correlation relationship, determining that the weft knitting machine has no fault; S1062: When the needle cylinder rotation speed and the vibration amplitude of the weaving roller cam do not satisfy the second preset correlation relationship, it is determined that the weft knitting machine has a fault.

3. The fault diagnosis method for a weft knitting machine based on triangular vibration response characteristics according to claim 2, characterized in that: The relationship formula corresponding to the second preset association relationship is: y=kx+b Wherein, x represents the needle cylinder speed, y represents the vibration amplitude of the weaving roller triangle, k represents the slope, and b represents the intercept.

4. The fault diagnosis method for a weft knitting machine based on triangular vibration response characteristics according to claim 3, characterized in that: In the relational expression corresponding to the second preset association relationship, k=0.00512, b=0.04893.

5. The fault diagnosis method for a weft knitting machine based on triangular vibration response characteristics according to claim 1, characterized in that: The vibration frequency of the weaving roller triangle is less than a preset frequency.

6. The fault diagnosis method for a weft knitting machine based on triangular vibration response characteristics according to claim 5, characterized in that: The preset frequency is 5Khz.

7. A fault diagnosis system for a weft knitting machine based on triangular vibration response characteristics, characterized in that: Used to execute the weft knitting machine fault diagnosis method based on triangular vibration response characteristics as described in any one of claims 1 to 6.

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