Ball screw, ball screw monitoring method, electronic device, and storage medium

Abstract

The application discloses a ball screw, a screw monitoring method thereof, an electronic device and a storage medium. The ball screw comprises a screw shaft, a nut and a plurality of balls. The screw shaft is inserted into the nut, and the gap between the screw shaft and the nut accommodates the balls. The screw shaft has a hollow cavity extending along the extension direction of the screw shaft. The hollow cavity is filled with a damping shock-absorbing filling layer. The damping shock-absorbing filling layer comprises an outer filling layer located at the outer layer and an inner filling layer filled in the outer filling layer. The screw shaft of the application is hollow. By filling the double-layer damping shock-absorbing filling layer in the hollow cavity, the lightweight design and the shock-absorbing effect of the screw are realized. Meanwhile, by detecting the amplitude and the number of revolutions of the screw shaft, the working condition of the ball screw is monitored, and timely alarm is given.

Description

Technical Field

[0001] This invention relates to the field of ball screw technology, and in particular to a ball screw, a ball screw monitoring method, an electronic device, and a storage medium thereof. Background Technology

[0002] Currently, to meet the requirements of high-speed stamping lines, the handling robots use ball screws with a large lead of 4080 and double nuts, which can travel 1.5 to 1.8 meters in a single stroke and have an alternating load of ≥32 reciprocations per minute.

[0003] Specifically, a ball screw includes a screw shaft, a nut, and balls. The outer circumferential surface of the screw shaft has an external thread groove, and the inner circumferential surface of the nut has an internal thread groove corresponding to the external thread groove. The screw shaft is inserted into the nut, and the balls are filled in the spiral ball rolling path formed by the external and internal thread grooves. By rotating the nut in the forward or reverse direction, the ball screw will be driven to reciprocate in the axial direction.

[0004] However, existing ball screws are prone to damage. According to the formula for calculating the limiting speed of a ball screw: υ=λ d1 / b 2 10 7 Where d1 is the minimum value of the ball screw axis. b The mounting spacing of the ball screw on handling robots and other working equipment. Therefore, when the speed of the ball screw approaches the limit speed (i.e., the maximum allowable speed), the rotating nut (ball) will resonate with the screw shaft, increasing the wear of the raceway.

[0005] Damage to ball screws is mainly manifested in ball wear and jamming caused by the peeling of the slideway. Currently, it can only be detected by appearance and cannot be used for fault detection or life extension. Summary of the Invention

[0006] Therefore, it is necessary to provide a ball screw and its monitoring method, electronic device and storage medium to address the technical problems of existing ball screws being easily damaged and unable to be fault detected.

[0007] The present invention provides a ball screw, including a screw shaft, a nut and a plurality of balls, wherein the screw shaft is inserted into the nut and the gap between the screw shaft and the nut accommodates the balls, the screw shaft has a hollow cavity extending along the extension direction of the screw shaft, the hollow cavity is filled with a damping and shock-absorbing filling layer, the damping and shock-absorbing filling layer includes an outer filling layer located on the outer layer and an inner filling layer filled within the outer filling layer.

[0008] Furthermore, the outer filling layer is made of resin material; the tensile strength of the outer filling layer is above 100 MPa; the inner filling layer is made of carbon fiber composite material; and the damping loss factor of the inner filling layer is greater than 1.5.

[0009] Furthermore, it also includes a vibration sensor fixed inside the hollow cavity.

[0010] Furthermore, the vibration sensor includes a vibration sensing plate fixed in the middle of the hollow cavity and a transmitter communicatively connected to the vibration sensing plate.

[0011] This invention provides a ball screw monitoring method as described above, comprising:

[0012] When the ball screw is installed and working on the working equipment, obtain the amplitude and / or number of revolutions of the screw shaft;

[0013] The allowable speed of the ball screw is determined based on the amplitude.

[0014] The permissible speed is compared with a speed warning threshold. If the permissible speed exceeds the speed warning threshold, an alarm is triggered. The speed warning threshold is determined based on the average of the maximum amplitude values, which is the average of the maximum amplitude values ​​of multiple damaged ball screws; and / or

[0015] The revolutions number is compared with the revolutions number warning threshold. If the revolutions number is greater than the revolutions number warning threshold, an alarm is issued. The revolutions number warning threshold is determined based on the average value of the maximum amplitude.

[0016] Furthermore, determining the permissible rotational speed of the ball screw based on the amplitude specifically includes: calculating the correlation coefficient λ2=k between the critical speed and the amplitude. f, where k is a preset constant, f is the amplitude, and the allowable speed of the ball screw is calculated as N1=λ2. d1 / b 2 a, where d1 is the minimum value of the ball screw axis. b The measured distance between the two ends of the ball screw installed on the working equipment is denoted by 'a', which is a constant.

[0017] Furthermore, the comparison of the permissible speed with the speed warning threshold, and the issuance of an alarm when the permissible speed exceeds the speed warning threshold, specifically includes:

[0018] The accuracy coefficient is set as the initial value, and the speed warning threshold is determined to be Nmax=k. n favg d1 / b1 2 a, where n is the accuracy coefficient, and favg is the average value of the maximum amplitude. b1 The mounting spacing of the damaged ball screw on the measuring equipment;

[0019] The permissible speed is compared with the speed warning threshold. If the permissible speed is greater than the speed warning threshold, an alarm is triggered.

[0020] In response to a reset alarm request, if the allowable speed is detected to be greater than the speed warning threshold again within a preset detection period, the system enters a fault monitoring mode; otherwise, after the detection period ends, the accuracy coefficient is increased by a preset increment value, and the speed warning threshold is corrected.

[0021] In response to a fault monitoring request, the system enters a fault monitoring mode. In this mode, if the number of times the permissible speed exceeds the speed warning threshold is exceeded within a preset monitoring period, the accuracy coefficient is increased by a preset increment value to correct the speed warning threshold, and an alarm is issued.

[0022] Furthermore, it also includes:

[0023] In response to the maximum amplitude mean average update request, the updated value of the maximum amplitude mean average is determined based on the newly added maximum amplitude of the damaged ball screw. , wherein the favg 当前（max） The average value of the maximum amplitude of the newly added damaged ball screw is calculated as favg current(max) = favg 当前 / n currently, where n 当前 This is the accuracy coefficient when replacing newly added damaged ball screws, where m is the cumulative number of damaged ball screws;

[0024] The average value of the maximum amplitude is updated to the updated value.

[0025] Furthermore, the comparison of the revolutions per minute (RPM) with the RPM warning threshold, and the issuance of an alarm when the RPM exceeds the RPM warning threshold, specifically includes:

[0026] Determine the accuracy coefficient and set the revolution warning threshold. Where Ca is the basic rated dynamic load, fw is the fixed load factor, n is the accuracy factor, L is the number of single runs of the ball screw, lg is the logarithmic function to the base 10, and Q is the preset amplification factor;

[0027] The revolutions per minute (RPM) is compared with the RPM warning threshold. If the RPM exceeds the RPM warning threshold, an alarm is triggered.

[0028] This invention provides an electronic device, comprising:

[0029] At least one processor; and,

[0030] A memory communicatively connected to at least one of the processors; wherein,

[0031] The memory stores instructions that can be executed by at least one of the processors to enable at least one of the processors to perform the lead screw monitoring method as described above.

[0032] The present invention provides a storage medium that stores computer instructions, which, when executed by a computer, are used to perform all the steps of the lead screw monitoring method as described above.

[0033] The ball screw shaft of this invention is hollow. By filling the hollow cavity with a double-layer damping and vibration-damping filler, the ball screw becomes lighter, but the deflection of the screw shaft increases and the rigidity decreases. Therefore, filling with a damping and vibration-damping filler layer achieves a lightweight design and vibration reduction effect for the ball screw. Simultaneously, by detecting the amplitude and rotational speed of the ball screw shaft, the working condition of the ball screw is monitored, and timely alarms are issued. Attached Figure Description

[0034] Figure 1 This is a schematic diagram of the structure of a ball screw according to an embodiment of the present invention;

[0035] Figure 2 This is a schematic diagram of a double-layer damping and shock-absorbing filling layer for a ball screw according to an embodiment of the present invention;

[0036] Figure 3 This is a schematic diagram of a lead screw shaft according to an embodiment of the present invention;

[0037] Figure 4 This is a cross-sectional view of a lead screw shaft according to an embodiment of the present invention;

[0038] Figure 5 This is a schematic diagram of the experimental setup;

[0039] Figure 6 This is a schematic diagram of the installation of a vibration sensor according to an embodiment of the present invention;

[0040] Figure 7 A comparison chart of amplitude curves;

[0041] Figure 8 This is a flowchart illustrating the process of a ball screw monitoring method as described above, according to an embodiment of the present invention.

[0042] Figure 9 A flowchart illustrating the preferred embodiment of the ball screw monitoring method described above is provided.

[0043] Figure 10 This is a schematic diagram of the hardware structure of an electronic device according to the present invention. Detailed Implementation

[0044] The specific embodiments of the present invention will be further described below with reference to the accompanying drawings. Identical components are indicated by the same reference numerals. It should be noted that the terms "front," "rear," "left," "right," "up," and "down" used in the following description refer to directions in the accompanying drawings, while the terms "inner" and "outer" refer to directions toward or away from the geometric center of a specific component, respectively.

[0045] like Figure 1 The diagram shown is a schematic representation of a ball screw according to an embodiment of the present invention. It includes a screw shaft 1, a nut 2, and a plurality of balls 3. The screw shaft 1 is inserted into the nut 2, and the gap between the screw shaft 1 and the nut 2 accommodates the balls 3. The screw shaft 1 has a hollow cavity 11 extending along its extension direction. The hollow cavity 11 is filled with a damping and shock-absorbing filling layer 4. Figure 2 As shown, the damping and shock-absorbing filling layer 4 includes an outer filling layer 41 located on the outer layer and an inner filling layer 42 filled within the outer filling layer 41.

[0046] Specifically, the ball screw includes a screw shaft 1, a nut 2, and a plurality of balls 3. The screw shaft 1 is inserted into the nut 2, and the gap between the screw shaft 1 and the nut 2 accommodates the balls 3. Specifically, an external thread groove is provided on the outer circumferential surface of the screw shaft 1, and an internal thread groove corresponding to the external thread groove is provided on the inner circumferential surface of the nut 2. The screw shaft 1 is inserted into the nut 2, and the balls 3 are filled into a spiral ball rolling path formed by the external and internal thread grooves.

[0047] The lead screw shaft 1 is hollow, forming an axially extending hollow cavity 11. The hollow cavity is filled with a double-layer damping and shock-absorbing filling layer 4, including an outer filling layer 41 located on the outer layer and an inner filling layer 42 filled within the outer filling layer 41.

[0048] Specifically, with Figure 3 For example, the lead screw shaft 1 includes a middle section 12 and two ends 13. The diameter of the middle section 12 is larger than that of the two ends 13. The length of the middle section 12 is L1, the diameter of the middle section is D, the diameter of the ends 13 is d1, the diameter of the hollow cavity 11 is d2, the density of the lead screw shaft 1 is ρ, and the total length of the lead screw shaft 1 is L. Therefore, its total mass G = ρ(1 / 4πD) 2 L1+ 1 / 4πd1 2 L2) = 8.387 x 10⁵ ρπ, while the mass of the hollowed-out portion of cavity 11 is G1 = ρ 1 / 4πd² 2 L.

[0049] The weight reduction target is to reduce the weight by more than 20%, which means G1 ≥ 0.2G. Therefore, d2 ≥ 17.5mm is calculated. Considering that the core also needs to be filled with material, the actual weight reduction is about 25.9%. Therefore, taking into account the filling material, d2 is finally chosen to be 20mm.

[0050] Specifically, the shaft material of the filler screw shaft was determined by experiment according to GB / T 229-2007 Charpy impact test method for metallic materials.

[0051] Material selection: Silicon manganese spring steel (60Si2Mn)

[0052] Heat treatment: Quenching at 870℃ + Tempering at 480℃

[0053] Characteristics: Tensile strength σs≥1275MPa, Impact energy Ak≥71J.

[0054] The lead screw shaft of this invention is hollow. By filling the hollow cavity with a double-layer damping and shock-absorbing filler, the lead screw becomes lighter, but the deflection of the lead screw shaft increases and the rigidity decreases. Therefore, filling with a damping and shock-absorbing filler layer achieves a lightweight design and shock absorption effect for the lead screw.

[0055] like Figure 4 As shown, in one embodiment, the outer filling layer 41 is made of resin material; the tensile strength of the outer filling layer 41 is above 100 MPa; the inner filling layer 42 is made of carbon fiber composite material; and the damping loss factor of the inner filling layer 42 is greater than 1.5.

[0056] Preferably, the outer filling layer 41 is a high-toughness polyimide resin material with a minimum tensile strength threshold of 100 MPa; the inner filling layer 42 is a CFRP-603A carbon fiber composite material with a damping loss factor greater than a preset factor threshold of 1.5.

[0057] In this embodiment, the innermost carbon fiber composite is cast as the inner filling layer 42. The composite filling is used to improve strength and damping loss to eliminate resonance. In order to avoid cracking caused by the brittleness of carbon fiber, a synthetic resin buffer layer is added between the outer layer of the lead screw body and the innermost carbon fiber layer as the outer filling layer 41, so as to achieve the lightweight design and vibration reduction effect of the lead screw.

[0058] Specifically, the outer filling layer 41 and the inner filling layer 42 were designed and tested according to GB / T 18258-2000 "Test Method for Damping Performance of Damping Materials". Experimental conditions: room temperature 25℃, sample dimensions: width 10mm, free end 200mm, thickness 3mm. Figure 5 The experimental setup shown includes: a fixture 31, a ball screw sample 32, an exciter 33, an amplifier 34, a signal generator 35, a recording device 36, a detection sensor 37, and a temperature control chamber 38.

[0059] Testing revealed that the outer filler layer 41 is a high-toughness material, 1.25mm on each side, while the inner filler layer 42 is a polymer with a high damping loss factor and a diameter of 17mm. Details are as follows:

[0060] 1. The outer filler layer 41 is made of polyimide resin (S 35 H 28 N207), the parameters are:

[0061] Density: 1.2 g / ml;

[0062] Coefficient of thermal expansion: 2 10 -5 ~3 10 -5 ;

[0063] Elongation: 5%~60%;

[0064] Tensile strength: 100 MPa.

[0065] 2. The inner filler layer 42 is made of carbon fiber composite material (CFRP-603A), with the following parameters:

[0066] Density: 1.6 g / ml;

[0067] Weight: 1.09kg;

[0068] Tensile strength: 1560 MPa;

[0069] Damping loss factor (η): 1.539.

[0070] Results and verification methods:

[0071] Theoretical calculations show that the amplitude decreased by 82.6% based on SN fatigue curve analysis, and the static bending performance decreased by 4.8% based on finite element analysis.

[0072] Experimental Test 1: Transient Excitation Test (Comparative Test)

[0073] Samples: solid shafts, hollow shafts (without a filler layer), and hollow shafts filled with a double-layer polymer (i.e., a damping and shock-absorbing filler layer).

[0074] Transient excitation tests were conducted on three types of specimens, and their vibration response was measured using a portable vibration measuring instrument. The maximum amplitude and decay time were recorded. The results are as follows:

[0075] Table 1 Test Results

[0076]

[0077] Experimental Test ②: Deflection Test

[0078] Samples: solid shafts, hollow shafts (without filler layer), and hollow shafts filled with a double layer of polymer.

[0079] Fix both ends of the lead screw shaft, mark the middle position, hang a 200Kg weight, and measure the deflection value Δs at the marked position, as shown in Table 2.

[0080] Table 2 Deflection Values

[0081]

[0082] in conclusion:

[0083] The screw has a hollow center, filled with an outer and an inner filler layer. The outer filler layer is made of a high-toughness material, while the inner filler layer is made of a high-damping material. This design enables the screw to be lightweight and provides vibration reduction, with its bending strength reduced by only 3.92%. This meets the allowable deviation of less than 5%.

[0084] The basic rated dynamic load of this embodiment is Ca2 = 40.4 kN, while the basic rated dynamic load of the prior art is Ca1 = 33.4 kN. Due to the lightweighting of the hollow-filled screw shaft and rotating nut, the total weight reduction is approximately 6.635 kg (a 21.9% decrease compared to the prior art screw of 30.18 kg). The axial load can be reduced by approximately 6.64%, therefore the axial load Fa2 ≈ 0.9336Fa1, and the load factor remains unchanged. Therefore, the lifespan of the ball screw in this embodiment is greater than or equal to ≥ 2.056 times that of the ball screw in the prior art.

[0085] like Figure 1 As shown, in one embodiment, a vibration sensor 5 is also included, which is fixed inside the hollow cavity 11.

[0086] This embodiment adds a vibration sensor to obtain the amplitude of the lead screw shaft, and detects the lead screw shaft by measuring the amplitude.

[0087] like Figure 6 As shown, in one embodiment, the vibration sensor 5 includes a vibration sensing plate 51 fixed in the middle of the hollow cavity 11 and a transmitter 52 communicatively connected to the vibration sensing plate 51.

[0088] Since the starting point of lead screw peeling is mainly in the middle part where the usage frequency is the highest and the deflection is the greatest, this embodiment installs the patch vibration sensing plate in the middle of the lead screw shaft to improve the detection accuracy.

[0089] Specifically, a miniature vibration sensor 51 is used in the middle section and installed in front of the inner filling layer. The power supply and signal are connected to the external transmitter 52 at the end of the lead screw shaft 1. The wireless transmitter 52 is installed at the end of the lead screw shaft 1. The analog data is transmitted to the programmable logic controller (PLC) for transposition, and then tested using an M20 screw hole.

[0090] like Figure 7 As shown, there is an amplitude curve 71 for detection using existing technology, and a vibration amplitude curve 72 using the hollow vibration reduction technology of the present invention.

[0091] It is quite evident that the amplitude is significantly reduced after adopting the hollow vibration reduction technology of the present invention.

[0092] like Figure 8 The diagram shown is a flowchart of a ball screw monitoring method according to an embodiment of the present invention, as described above, including:

[0093] Step S801: Obtain the amplitude and / or number of revolutions of the ball screw shaft when the ball screw is installed on the working equipment.

[0094] Step S802: Determine the allowable speed of the ball screw based on the amplitude;

[0095] Step S803: Compare the allowable speed with the speed warning threshold. If the allowable speed is greater than the speed warning threshold, an alarm is triggered. The speed warning threshold is determined based on the average of the maximum amplitude values, which are determined by measuring the maximum amplitude of multiple damaged ball screws; and / or

[0096] Step S804: Compare the number of revolutions with the number of revolutions warning threshold. If the number of revolutions is greater than the number of revolutions warning threshold, an alarm is issued. The number of revolutions warning threshold is determined based on the average value of the maximum amplitude.

[0097] Specifically, the present invention can be applied to monitoring devices for ball screws, such as programmable logic controllers (PLCs).

[0098] Specifically, in step S801, the present invention monitors the amplitude or rotational speed of the ball screw shaft. As the rotational speed of the ball screw increases, it gradually approaches the natural frequency of the screw shaft, thus causing resonance and increased wear. Therefore, it must be used below the resonance point (dangerous speed). Therefore, in step S802, the amplitude is converted into an allowable rotational speed. Then, in step S803, the allowable rotational speed is compared with a rotational speed warning threshold, and an alarm is issued when the allowable rotational speed exceeds the rotational speed warning threshold. Furthermore, the lifespan of a ball screw refers to the total number of rotations the ball screw has completed until the initial surface spalling due to rolling fatigue of the material occurs on either the rolling surface or the steel balls. Therefore, in step S804, the rotational speed is compared with a rotational speed warning threshold, and an alarm is issued when the rotational speed exceeds the rotational speed warning threshold.

[0099] The amplitude can be obtained through the aforementioned vibration sensor; while the actual number of revolutions of the lead screw is sampled by the forward and reverse rotation of its drive unit. The drive unit of the lead screw consists of a servo motor, a synchronous belt, and a synchronous pulley. The synchronous pulley is fixedly installed on the rotating nut of the lead screw. The servo motor drives the synchronous pulley to rotate forward and reverse through the synchronous belt to obtain the linear motion of the rotating nut on the lead screw. Therefore, by collecting the forward and reverse rotation of the servo motor and then using the transmission ratio of the synchronous pulley, the actual number of revolutions of the rotating nut of the lead screw, i.e., the actual number of revolutions of the ball screw, can be calculated.

[0100] This invention monitors the working condition of the ball screw by detecting the amplitude and rotation speed of the lead screw shaft, and issues timely alarms.

[0101] In one embodiment, determining the permissible rotational speed of the ball screw based on the amplitude specifically includes: calculating the correlation coefficient λ2=k between the critical speed and the amplitude. f, where k is a preset constant, f is the amplitude, and the allowable speed of the ball screw is calculated as N1=λ2. d1 / b 2 a, where d1 is the minimum value of the ball screw axis. b The measured distance between the two ends of the ball screw mounted on the working equipment is denoted by 'a', which is a constant, preferably 10. 7 .

[0102] Specifically, the permissible rotational speed at the dangerous speed is N1 = λ2. d1 / b 2 a, where d1 is the minimum value of the ball screw axis, the b The measured distance between the two ends of the ball screw installed on the working equipment.

[0103] Preferably, the permissible rotational speed at the dangerous speed is N1 = λ2. d1 / b 2 10 7 .

[0104] The correlation coefficient λ2 between the dangerous velocity and the amplitude is a coefficient related to the installation method, as shown in Table 3.

[0105] Table 3. Relationship between Correlation Coefficients and Installation Methods

[0106]

[0107] Ball screws are used in multi-axis robotic arms. They are installed by directly fastening one end of the screw to the robotic body via an external threaded nut, while the other end uses a 3-5° ball joint and is installed on the other end of the robotic arm body. Therefore, the fastening method is: fixed-free.

[0108] According to GB / T 229-2007 "Charpy Impact Test Method for Metallic Materials", the amplitude value is correlated with the correlation coefficient, i.e., λ2∝f. When λ2 is set to a fixed value of 1.875, then λ2∝1.875. f. That is, the preset constant k is preferably 1.875.

[0109] Therefore, in this embodiment, the correlation coefficient is determined by detecting the amplitude, and the corresponding maximum allowable speed Nmax is calculated as the threshold for system monitoring.

[0110] In one embodiment, comparing the permissible speed with a speed warning threshold, and issuing an alarm when the permissible speed exceeds the speed warning threshold, specifically includes:

[0111] The accuracy coefficient is set as the initial value, and the speed warning threshold is determined to be Nmax=k. n favg d1 / b1 2 a, where n is the accuracy coefficient, and favg is the average value of the maximum amplitude. b1 The mounting spacing of the damaged ball screw on the measuring equipment;

[0112] The permissible speed is compared with the speed warning threshold. If the permissible speed is greater than the speed warning threshold, an alarm is triggered.

[0113] In response to a reset alarm request, if the allowable speed is detected to be greater than the speed warning threshold again within a preset detection period, the system enters a fault monitoring mode; otherwise, after the detection period ends, the accuracy coefficient is increased by a preset increment value, and the speed warning threshold is corrected.

[0114] In response to a fault monitoring request, the system enters a fault monitoring mode. In this mode, if the number of times the permissible speed exceeds the speed warning threshold is exceeded within a preset monitoring period, the accuracy coefficient is increased by a preset increment value to correct the speed warning threshold, and an alarm is issued.

[0115] Specifically, because of the installation spacing of each lead screw b1 is the actual measured value on site, which has a deviation. Therefore, the preset threshold in this study uses multiple raceway peeling and ball wear, and damaged ball screws that are unable to operate due to dacca as samples. After testing ≥300,000 times on the same robotic arm, the average maximum amplitude fmax is obtained using the same algorithm.

[0116] To maximize the accuracy of sampling the maximum amplitude of a damaged ball screw, it is necessary to consider the actual load condition of the screw. This is to shield the interference from the robot arm during idle or debugging operations when it is not gripping a load. The data sampling will be combined with the load rate of the robot arm, which is the load rate of the servo motor driving the screw, monitored by the computer. By using the alarm and stop function of the shielding equipment, the range of 100% overload will be selected to find the peak value of the amplitude. The feedback from the equipment will be used to obtain the minimum error.

[0117] The maximum average amplitude of each damaged ball screw is calculated, which can monitor the range where the load rate exceeds 100%. For each range where the load rate exceeds 100%, the peak value of the amplitude in that range is obtained. The average of the peak values ​​of the amplitude in multiple ranges where the load rate exceeds 100% is taken to obtain the maximum average amplitude fmax of the damaged ball screw.

[0118] The average maximum amplitude can be obtained by mounting multiple damaged ball screws on the same measuring device, measuring the average maximum amplitude of each damaged ball screw, and then averaging these average maximum amplitudes. For example, to calculate: Where p is the number of samples of damaged ball screws used for measurement, and f max，j Let p be the mean maximum amplitude of the j-th damaged ball screw. The damaged ball screw is defined as a ball screw exhibiting moderate spalling online, with a sample size p ≥ 10.

[0119] Then, the conversion speed warning threshold is calculated based on the average of the maximum amplitude. Since the permissible speed at the dangerous speed is N1 = λ2... d1 / b 2 a. Since λ2 is determined based on the amplitude, the correlation coefficient between the dangerous velocity for setting the warning threshold and the amplitude is λ'2=k. n favg, where n is the precision coefficient. Adjusting the precision coefficient adjusts the warning threshold. The final warning threshold is Nmax = k. n favg d1 / b1 2 a, where n is the accuracy coefficient, favg is the average value of the maximum amplitude, and the... b1 The installation spacing of the damaged ball screw on the measuring equipment.

[0120] If N1 is greater than Nmax, it can be determined that the lead screw is experiencing dangerous vibration, and an alarm message will be sent.

[0121] For the warning threshold, automatic accuracy correction settings are implemented:

[0122] (1) Initial settings: The initial value of the precision coefficient of n is preferably 20%;

[0123] (2) When N1>Nmax is triggered: Manual intervention is required to check the ball screw. ① If there is no problem, the user selects the "Reset Alarm" mode to trigger a reset alarm request. The industrial control computer responds to the reset alarm request. If it is not triggered again within a certain detection period, the value of n will be increased to n+5%, and the speed warning threshold will be corrected based on the new value of n. If it is triggered again, the "Fault Monitoring" mode will be entered. The detection period is the number of times the ball screw reciprocates under the drive of the working equipment, for example, 300,000 reciprocating movements.

[0124] ② If a problem is found with the ball screw, select the "Fault Monitoring" mode to trigger a fault monitoring request. The industrial control computer responds to the request and monitors the number of times N1 > Nmax is triggered within a certain monitoring period. If the number of triggers within the monitoring period is ≥ 5, the n value will be directly amplified (n + 5%), triggering another alarm. Manual intervention is required, and the speed warning threshold is adjusted based on the new n value. When the n value accumulates to 100%, the ball screw must be forcibly replaced. The monitoring period is the number of reciprocating motions of the ball screw driven by the working equipment, for example, 300,000 reciprocating motions.

[0125] This embodiment achieves automatic accuracy correction by adjusting the accuracy coefficient.

[0126] In one embodiment, it further includes:

[0127] In response to the maximum amplitude mean average update request, the updated value of the maximum amplitude mean average is determined based on the newly added maximum amplitude of the damaged ball screw. , wherein the favg 当前（max） The average value of the maximum amplitude of the newly added damaged ball screw is calculated as favg current(max) = favg 当前 / n currently, where n 当前 This is the accuracy coefficient when replacing newly added damaged ball screws, where m is the cumulative number of damaged ball screws;

[0128] The average value of the maximum amplitude is updated to the updated value.

[0129] Specifically, in response to the maximum amplitude mean average update request, the updated value of the maximum amplitude mean average is determined based on the newly added maximum amplitude of the damaged ball screw. Among them, let favg 当前 The average value of the maximum amplitude is calculated based on the maximum amplitude of the newly added damaged ball screws, where m is the cumulative number of damaged ball screws since the first one with recorded amplitude.

[0130] To monitor the trend of lead screw damage, an accuracy coefficient 'n' is used for process monitoring, with a correction coefficient set within the range of 20%-100%. Therefore, favg 当前 The maximum value should be converted to favg (max) = favg 当前 / n currently, where n 当前 This refers to the accuracy factor when replacing a newly added damaged ball screw.

[0131] Specifically, based on the setting of the n value (after it is greater than 100), the value of favg is gradually adjusted. Multiple ball screws are monitored through a network, and favg is adjusted once a ball screw is damaged and replaced.

[0132] During ball screw monitoring, when the n value accumulates to 100%, the screw must be forcibly replaced. However, with manual intervention, the screw might be replaced before the n value reaches 100%, thus affecting the accuracy of n readings. 当前 Less than or equal to 100%. Therefore, favg current (max) = favg 当前 / nCurrent.

[0133] This embodiment updates the average value of the maximum amplitude, thereby updating the speed warning threshold and the number of revolutions warning threshold.

[0134] In one embodiment, comparing the revolutions per minute (RPM) with a RPM warning threshold, and issuing an alarm when the RPM exceeds the warning threshold, specifically includes:

[0135] Determine the accuracy coefficient and set the revolution warning threshold. Where Ca is the basic rated dynamic load, fw is the fixed load factor, n is the accuracy factor, J is the number of single runs of the ball screw, lg is the logarithmic function to the base 10, and Q is the preset amplification factor;

[0136] The revolutions per minute (RPM) is compared with the RPM warning threshold. If the RPM exceeds the RPM warning threshold, an alarm is triggered.

[0137] The life of a ball screw refers to the total number of revolutions it completes before the initial surface spalling due to rolling fatigue of the material occurs on either the rolling surface or the steel balls. The calculation formula is as follows:

[0138] ,in:

[0139] —L: Rated life (total revolutions), rev

[0140] —Ca: Basic rated dynamic load, N

[0141] —Fa: Axial load, N

[0142] —fw: Load factor

[0143] Ca can be obtained from the design drawings. The load factor fw is fixed, while Fa is a dynamic value. Combining stress and online vibration amplitude, the amplitude is detected in real time. A mathematical model calculates the total number of revolutions required for the lead screw to reach its service life based on the maximum amplitude. The cumulative number of revolutions of the target lead screw is calculated. When the cumulative number of revolutions exceeds the predicted total number of revolutions, an alarm is sent. This alarm will not stop the line, but it cannot be cleared unless the monitoring frequency is increased in the extended maintenance count setting. The extended maintenance count is achieved by increasing a value in Lmax, extending the monitoring period for the maximum value. (This value is input through the PLC interface and fed back to the industrial control computer.)

[0144] Fa is calculated by converting online vibration amplitude and the number of single screw cycles. By plotting the dynamic SN curve, the model relationship between Fa∝L and amplitude / number of cycles is obtained. L is the cumulative number of revolutions in a single operation of the ball screw. The model formula relating the number of revolutions to the amplitude has a warning threshold. Preferably, the preset magnification factor Q is 10. 6The initial threshold sampling for calculating Lmax is obtained by averaging the number of uses of P damaged lead screws sampled for calculating the speed warning threshold Nmax. Specifically, Ca is the average basic rated dynamic load of the P damaged lead screws sampled for calculating the speed warning threshold Nmax, fw is the average axial load of the P damaged lead screws sampled for calculating the speed warning threshold Nmax, and L is the average number of single runs of the P damaged lead screws sampled for calculating the speed warning threshold Nmax.

[0145] Therefore, the rotational speed warning threshold can ultimately be obtained. Simultaneously, each update to the accuracy coefficient will update the rotational speed warning threshold. The rotational speed monitoring for each implemented ball screw will combine amplitude monitoring to obtain the current rotational speed L of the ball screw during operation. When L current ≥ Lmax, the device will issue an alarm. After an alarm, manual adjustment of the monitoring duration is required, and the device must be replaced within a short period.

[0146] like Figure 9 The diagram shown is a flowchart of a ball screw monitoring method according to the preferred embodiment of the present invention, as described above, including:

[0147] Step S901, the device goes online;

[0148] Step S902: Wireless vibration detection acquires amplitude data;

[0149] Step S903: The analog amplitude data is transmitted to the industrial computer for λ2 transpose.

[0150] Step S904: The industrial control computer automatically calculates the speed of N1;

[0151] Step S905: If N1≤Nmax, continue the detection; otherwise, proceed to step S908.

[0152] Step S906: The industrial control computer calculates the total number of current screw rotations L1;

[0153] In step S907, if L1≤Lmax, the system will operate normally and wait for the next action; otherwise, the alarm will not be interrupted but cannot be cleared. Temporary clearing can be achieved by setting the number of extended warranty cycles, and step S908 will be executed.

[0154] Step S908: The industrial control computer alarm is transmitted to the PLC touch screen for notification (not line stoppage).

[0155] Step S909: If the condition of the lead screw is not found to be damaged, reset the alarm and proceed to step 910; otherwise, enter the fault monitoring mode and proceed to step S911.

[0156] Step S910: If no further triggering occurs within 300,000 cycles, n+5%, proceed to step S902; otherwise, enter fault monitoring mode and proceed to step S911.

[0157] Step S911: If the number of triggers is ≤5 within 300,000 triggers, increment n by 5% and proceed to step S902; otherwise, increment n by 5%.

[0158] Step S912: If n≤100%, proceed to step S911; otherwise, replace the lead screw.

[0159] like Figure 10 The diagram shown is a hardware structure schematic of an electronic device according to the present invention, comprising:

[0160] At least one processor 1001; and,

[0161] A memory 1002 is communicatively connected to at least one of the processors 1001; wherein,

[0162] The memory 1002 stores instructions that can be executed by at least one of the processors to enable the at least one of the processors to perform the lead screw monitoring method as described above.

[0163] Figure 10 Take processor 1001 as an example.

[0164] The electronic device may also include an input device 1003 and a display device 1004.

[0165] The processor 1001, memory 1002, input device 1003 and display device 1004 can be connected by a bus or other means. The figure shows an example of connection by a bus.

[0166] The memory 1002, as a non-volatile computer-readable storage medium, can be used to store non-volatile software programs, non-volatile computer-executable programs, and modules, such as the program instructions / modules corresponding to the lead screw monitoring method in the embodiments of this application. Figure 8 The method flow is shown. The processor 1001 executes various functional applications and data processing by running non-volatile software programs, instructions, and modules stored in the memory 1002, thereby realizing the lead screw monitoring method in the above embodiments.

[0167] The memory 1002 may include a program storage area and a data storage area. The program storage area may store the operating system and applications required for at least one function; the data storage area may store data created based on the use of the lead screw monitoring method, etc. Furthermore, the memory 1002 may include high-speed random access memory and may also include non-volatile memory, such as at least one disk storage device, flash memory device, or other non-volatile solid-state storage device. In some embodiments, the memory 1002 may optionally include memory remotely located relative to the processor 1001, and these remote memories can be connected to the apparatus performing the lead screw monitoring method via a network. Examples of such networks include, but are not limited to, the Internet, corporate intranets, local area networks, mobile communication networks, and combinations thereof.

[0168] The input device 1003 can receive user clicks and generate signal inputs related to user settings and function control of the lead screw monitoring method. The display device 1004 may include a display screen or other display equipment.

[0169] When one or more modules are stored in the memory 1002, and are run by one or more processors 1001, the lead screw monitoring method in any of the above method embodiments is executed.

[0170] This invention monitors the working condition of the ball screw by detecting the amplitude and rotation speed of the lead screw shaft, and issues timely alarms.

[0171] One embodiment of the present invention provides a storage medium that stores computer instructions, which, when executed by a computer, are used to perform all the steps of the lead screw monitoring method described above.

[0172] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention. Therefore, the scope of protection of this patent should be determined by the appended claims.

Claims

1. A method for monitoring the ball screw, characterized in that, A ball screw includes a screw shaft (1), a nut (2), and a plurality of balls (3), wherein the screw shaft (1) is inserted into the nut (2), and the ball balls (3) are accommodated in the gap between the screw shaft (1) and the nut (2), the screw shaft (1) has a hollow cavity (11) extending along the extension direction of the screw shaft (1), the hollow cavity (11) is filled with a damping and shock-absorbing filling layer (4), the damping and shock-absorbing filling layer (4) includes an outer filling layer (41) located on the outer layer and an inner filling layer (42) filled in the outer filling layer (41), the method comprising: When the ball screw is installed and working on the working equipment, obtain the amplitude and / or number of revolutions of the screw shaft; The allowable speed of the ball screw is determined based on the amplitude. The permissible speed is compared with a speed warning threshold. If the permissible speed exceeds the speed warning threshold, an alarm is triggered. The speed warning threshold is determined based on the average of the maximum amplitude values, which is the average of the maximum amplitude values ​​of multiple damaged ball screws; and / or The revolutions number is compared with the revolutions number warning threshold. If the revolutions number is greater than the revolutions number warning threshold, an alarm is issued. The revolutions number warning threshold is determined based on the average value of the maximum amplitude. The step of comparing the permissible speed with the speed warning threshold, and issuing an alarm when the permissible speed exceeds the speed warning threshold, specifically includes: The accuracy coefficient is set to its initial value, and the speed warning threshold is determined to be... Where n is the precision coefficient. The average value of the maximum amplitude. The installation spacing of the damaged ball screw on the measuring equipment is k, which is a preset constant, d1 is the minimum value of the ball screw shaft, and a is a constant. The permissible speed is compared with the speed warning threshold. If the permissible speed is greater than the speed warning threshold, an alarm is triggered. In response to a reset alarm request, if the allowable speed is detected to be greater than the speed warning threshold again within a preset detection period, the system enters a fault monitoring mode; otherwise, after the detection period ends, the accuracy coefficient is increased by a preset increment value, and the speed warning threshold is corrected. In response to a fault monitoring request, the system enters a fault monitoring mode. In this mode, if the number of times the permissible speed exceeds the speed warning threshold is exceeded within a preset monitoring period, the accuracy coefficient is increased by a preset increment value to correct the speed warning threshold, and an alarm is issued.

2. The lead screw monitoring method according to claim 1, characterized in that, The outer filling layer (41) is made of resin material; the tensile strength of the outer filling layer (41) is above 100 MPa; the inner filling layer (42) is made of carbon fiber composite material; the damping loss factor of the inner filling layer (42) is greater than 1.

5.

3. The lead screw monitoring method according to claim 1 or 2, characterized in that, The ball screw also includes a vibration sensor (5) fixed inside the hollow cavity (11).

4. The lead screw monitoring method according to claim 3, characterized in that, The vibration sensor (5) includes a vibration sensing plate (51) fixed in the middle of the hollow cavity (11) and a transmitter (52) communicatively connected to the vibration sensing plate (51).

5. The lead screw monitoring method according to claim 1, characterized in that, The step of determining the permissible rotational speed of the ball screw based on the amplitude specifically includes: calculating the correlation coefficient between the critical speed and the amplitude. Where f is the amplitude, the allowable speed of the ball screw is calculated as follows: ,in The measured distance between the two ends of the ball screw installed on the working equipment.

6. The lead screw monitoring method according to claim 1, characterized in that, Also includes: In response to the maximum amplitude mean average update request, the updated value of the maximum amplitude mean average is determined based on the newly added maximum amplitude of the damaged ball screw. , wherein, the favg 当前（max） The average value of the maximum amplitude of the newly added damaged ball screw is calculated as favg current(max) = favg 当前 / n currently, where n 当前 This represents the accuracy factor when replacing newly added damaged ball screws, where m is the cumulative number of damaged ball screws, favg 当前 The average value of the maximum amplitude calculated based on the maximum amplitude of the newly added damaged ball screw; The average value of the maximum amplitude is updated to the updated value.

7. The lead screw monitoring method according to claim 1, characterized in that, The comparison of the revolutions per minute (RPM) with a RPM warning threshold, and the issuance of an alarm when the RPM exceeds the warning threshold, specifically includes: Determine the accuracy coefficient and set the revolution warning threshold. Where Ca is the basic rated dynamic load, fw is the fixed load factor, n is the accuracy factor, J is the number of single runs of the ball screw, lg is the logarithmic function with base 10, and Q is the preset amplification factor. The revolutions per minute (RPM) is compared with the RPM warning threshold. If the RPM exceeds the RPM warning threshold, an alarm is triggered.

8. An electronic device, characterized in that, include: At least one processor; as well as, A memory communicatively connected to at least one of the processors; wherein, The memory stores instructions that can be executed by at least one of the processors to enable at least one of the processors to perform the lead screw monitoring method as described in any one of claims 1 to 7.

9. A storage medium, characterized in that, The storage medium stores computer instructions, which, when executed by the computer, are used to perform all the steps of the lead screw monitoring method as described in any one of claims 1 to 7.

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