絲杠動態(tài)剛度怎么檢測呢?
來源:http://www.fuelcell.ac.cn/ 日期:2025-07-14 發(fā)布人:
絲杠動態(tài)剛度的測量是評估其在動態(tài)載荷下抵抗變形能力的關(guān)鍵環(huán)節(jié),需通過設(shè)備和規(guī)范流程操作,以獲取準(zhǔn)確數(shù)據(jù)。以下是具體的測量方法與步驟。
The measurement of the dynamic stiffness of a screw is a key step in evaluating its ability to resist deformation under dynamic loads, and requires the use of professional equipment and standardized procedures to obtain accurate data. The following are specific measurement methods and steps.
測量前的準(zhǔn)備工作需充分到位。需明確絲杠的型號、規(guī)格及使用工況,如公稱直徑、導(dǎo)程、工作轉(zhuǎn)速等,根據(jù)這些參數(shù)選擇適配的測量設(shè)備,常用的有動態(tài)剛度測試系統(tǒng)、激振器、力傳感器、位移傳感器等。檢查設(shè)備的校準(zhǔn)狀態(tài),確保傳感器的精度(力傳感器誤差不超過 ±1%,位移傳感器分辨率不低于 0.1μm)和測試系統(tǒng)的穩(wěn)定性符合要求。將絲杠安裝在專用測試平臺上,模擬實際工作時的支撐方式(如兩端固定、一端固定一端游動),安裝時需保證絲杠軸線與測試平臺平行,避免因安裝偏差引入測量誤差。同時清理絲杠表面的油污、雜質(zhì),檢查絲杠螺母的配合間隙,確保運動順暢無卡滯,必要時添加適量潤滑油減少摩擦影響。
The preparation work before measurement needs to be fully in place. Firstly, it is necessary to clarify the model, specifications, and operating conditions of the screw, such as nominal diameter, lead, and working speed. Based on these parameters, suitable measuring equipment should be selected, including dynamic stiffness testing systems, exciters, force sensors, displacement sensors, etc. Check the calibration status of the equipment to ensure that the accuracy of the sensors (force sensor error not exceeding ± 1%, displacement sensor resolution not less than 0.1 μ m) and the stability of the testing system meet the requirements. Install the lead screw on a dedicated testing platform and simulate the actual support method during operation (such as fixing both ends, fixing one end, and moving one end). During installation, ensure that the axis of the lead screw is parallel to the testing platform to avoid measurement errors caused by installation deviations. At the same time, clean the oil and impurities on the surface of the screw, check the fit clearance of the screw nut, ensure smooth movement without jamming, and add an appropriate amount of lubricating oil if necessary to reduce friction effects.
激振與信號采集是核心環(huán)節(jié)。采用激振器對絲杠施加動態(tài)激勵,激振點通常選擇在絲杠中部或螺母上,激勵方式可采用正弦掃頻或隨機激勵,掃頻范圍需覆蓋絲杠的工作轉(zhuǎn)速對應(yīng)的頻率范圍,確保包含共振頻率點。力傳感器安裝在激振器與絲杠之間,用于采集激振力信號;位移傳感器(如激光位移計、電渦流傳感器)則安裝在靠近激振點的位置,采集絲杠在動態(tài)激勵下的位移響應(yīng)信號,傳感器需與絲杠表面保持垂直,避免角度偏差導(dǎo)致的測量值失真。測試系統(tǒng)需同步采集力信號和位移信號,采樣頻率應(yīng)設(shè)置為激勵頻率的 5-10 倍,以保證信號的完整性。
Excitation and signal acquisition are the core components. Dynamic excitation is applied to the screw using an exciter, with the excitation point usually selected in the middle of the screw or on the nut. The excitation method can be sine sweep frequency or random excitation, and the sweep frequency range should cover the frequency range corresponding to the working speed of the screw to ensure the inclusion of resonance frequency points. The force sensor is installed between the exciter and the screw to collect the excitation force signal; Displacement sensors (such as laser displacement sensors and eddy current sensors) are installed near the excitation point to collect displacement response signals of the screw under dynamic excitation. The sensor needs to be perpendicular to the surface of the screw to avoid measurement distortion caused by angular deviation. The testing system needs to synchronously collect force signals and displacement signals, and the sampling frequency should be set to 5-10 times the highest excitation frequency to ensure signal integrity.
數(shù)據(jù)處理與分析需遵循方法。通過測試系統(tǒng)的數(shù)據(jù)分析軟件,對采集到的力和位移信號進行處理,計算出絲杠在不同頻率下的動態(tài)剛度值(動態(tài)剛度 = 激振力幅值 / 位移響應(yīng)幅值)。繪制動態(tài)剛度隨頻率變化的曲線,曲線中出現(xiàn)的低谷對應(yīng)絲杠的共振頻率,此頻率下的動態(tài)剛度,是評估絲杠動態(tài)性能的關(guān)鍵指標(biāo)。分析曲線時需關(guān)注工作頻率范圍內(nèi)的動態(tài)剛度變化趨勢,若在常用轉(zhuǎn)速對應(yīng)的頻率下剛度值過低,說明絲杠在該工況下易產(chǎn)生較大變形,可能影響傳動精度。同時需多次重復(fù)測量(通常 3-5 次),取平均值作為終結(jié)果,減少隨機誤差的影響。
Data processing and analysis must follow professional methods. By using the data analysis software of the testing system, the collected force and displacement signals are processed to calculate the dynamic stiffness values of the screw at different frequencies (dynamic stiffness=excitation force amplitude/displacement response amplitude). Draw a curve of dynamic stiffness as a function of frequency, where the troughs in the curve correspond to the resonance frequency of the screw. The lowest dynamic stiffness occurs at this frequency, which is a key indicator for evaluating the dynamic performance of the screw. When analyzing the curve, attention should be paid to the dynamic stiffness variation trend within the working frequency range. If the stiffness value is too low at the frequency corresponding to the commonly used speed, it indicates that the screw is prone to significant deformation under this working condition, which may affect the transmission accuracy. Simultaneously, multiple repeated measurements (usually 3-5 times) are required, and the average value is taken as the final result to reduce the impact of random errors.
測量過程中的操作要點需嚴(yán)格把控。激振力的大小需合理設(shè)定,既要保證信號的信噪比,又不能超過絲杠的承載極限,避免因過載導(dǎo)致絲杠變形。測試環(huán)境需保持穩(wěn)定,避免外界振動(如地面振動、設(shè)備運行振動)和電磁干擾(如電機、變頻器產(chǎn)生的電磁場)影響傳感器信號,必要時可搭建隔振平臺或?qū)鞲衅骶€纜進行屏蔽處理。對于長絲杠,需考慮其自重引起的彎曲變形對測量的影響,可在測試前進行預(yù)加載,抵消部分自重變形。此外,測量時需記錄環(huán)境溫度、濕度等參數(shù),因為溫度變化可能導(dǎo)致絲杠熱脹冷縮,影響其剛度特性,后續(xù)分析時可作為參考因素。
The key points of operation during the measurement process need to be strictly controlled. The magnitude of the excitation force should be set reasonably, ensuring the signal-to-noise ratio of the signal while not exceeding the bearing limit of the screw, to avoid permanent deformation of the screw due to overload. The testing environment should be kept stable to avoid external vibrations (such as ground vibrations, equipment operation vibrations) and electromagnetic interference (such as electromagnetic fields generated by motors and frequency converters) affecting sensor signals. If necessary, an isolation platform can be built or sensor cables can be shielded. For long filament bars, it is necessary to consider the impact of bending deformation caused by their own weight on measurement. Preloading can be performed before testing to offset some of the self weight deformation. In addition, it is necessary to record environmental parameters such as temperature and humidity during measurement, as temperature changes may cause thermal expansion and contraction of the screw, affecting its stiffness characteristics, which can be used as reference factors for subsequent analysis.
動態(tài)剛度的評估需結(jié)合實際應(yīng)用場景。根據(jù)測量結(jié)果,對比設(shè)計要求或行業(yè)標(biāo)準(zhǔn),判斷絲杠的動態(tài)性能是否達(dá)標(biāo)。若用于精密機床進給系統(tǒng),需確保在工作頻率范圍內(nèi)動態(tài)剛度穩(wěn)定且足夠高,以保證加工精度;若用于普通傳動機構(gòu),可適當(dāng)放寬要求,但需避免共振頻率落入常用工作頻率區(qū)間。對于測量中發(fā)現(xiàn)的剛度異常(如某一頻率段剛度驟降),需排查是否由絲杠本身缺陷(如螺紋精度不足、材料不均勻)或測試系統(tǒng)故障引起,必要時更換絲杠樣本重新測量驗證。
The evaluation of dynamic stiffness needs to be combined with practical application scenarios. Based on the measurement results, compare the design requirements or industry standards to determine whether the dynamic performance of the screw meets the standards. If used in precision machine tool feed systems, it is necessary to ensure stable and sufficiently high dynamic stiffness within the operating frequency range to ensure machining accuracy; If used for ordinary transmission mechanisms, the requirements can be appropriately relaxed, but it is necessary to avoid resonance frequencies falling into the commonly used operating frequency range. For stiffness anomalies found during measurement (such as a sudden drop in stiffness in a certain frequency range), it is necessary to investigate whether they are caused by defects in the lead screw itself (such as insufficient thread accuracy, uneven material) or testing system failures. If necessary, replace the lead screw sample and re measure and verify.
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