滾珠絲杠由螺桿、螺母、滾珠和回珠器組成,主要功能是將旋轉運動轉換成直線運動。在精密設備尤其是數控設備上廣泛使用,由控制系統(tǒng)發(fā)出的脈沖信號控制伺服電機的旋轉,再由精密滾珠絲杠將伺服電機的旋轉運動轉換成工作臺的直線運動,從而實現工件的加工軌跡控制。因此,裝配工藝及精度檢測都很嚴格,對裝配工人的技術要求也較高。

　　A ball screw is composed of a screw, nut, ball, and ball return device, and its main function is to convert rotational motion into linear motion. Widely used in precision equipment, especially CNC equipment, the pulse signal emitted by the control system controls the rotation of the servo motor, and then the precision ball screw converts the rotational motion of the servo motor into linear motion of the worktable, thereby achieving the control of the machining trajectory of the workpiece. Therefore, the assembly process and precision testing are very strict, and the technical requirements for assembly workers are also high.

　　一、故障現象　　某數控設備有限公司在數控車床精密滾珠絲杠裝配后進行靜態(tài)精度檢查時合格,但在試車后或使用一段時間后出現精密滾珠絲杠的軸向跳動嚴重超差,影響了機床的加工精度,設備返修率為43%,給企業(yè)帶來巨大的經濟損失和聲譽損失。

　　1、 Fault phenomenon: A certain CNC equipment Co., Ltd. passed the static accuracy inspection after assembling the precision ball screw of the CNC lathe. However, after testing or using it for a period of time, the axial runout of the precision ball screw seriously exceeded the tolerance, affecting the machining accuracy of the machine tool. The equipment repair rate was 43%, causing huge economic and reputation losses to the enterprise.

　　二、故障原因分析

　　2、 Fault cause analysis

　　1.精密滾珠絲杠精度達不到要求　　滾珠絲杠在入庫時已進行了精度檢驗,可排除本身的質量問題。但細長軸類零件(機床絲桿等)在保管時應該采用垂直放置,以免受重力變形影響精度。該滾珠絲杠采專用包裝箱垂直放置,在裝配后的靜態(tài)檢查合格,因此可以排除此項。

　　1. The precision of the precision ball screw does not meet the requirements. The ball screw has undergone precision inspection when it is stored, and its own quality problems can be ruled out. However, slender shaft components (such as machine tool screws) should be placed vertically during storage to avoid accuracy being affected by gravity deformation. The ball screw is placed vertically in a special packaging box and passed the static inspection after assembly, so this item can be excluded.

　　2.裝配不當損壞了絲杠的精度　　通過了解,裝配工人對精密滾珠絲杠組件熟悉的,裝配時也是格外小心,完全按裝配工藝進行的,因此也排除了這種可能。

　　2. Improper assembly damaged the accuracy of the screw. Through understanding, assembly workers are familiar with precision ball screw components and are particularly careful during assembly, completely following the assembly process. Therefore, this possibility has also been ruled out.

　　3.機床行程超程,工作臺發(fā)生碰撞,導致精度損壞　　操作機床時發(fā)生超程,容易導致機床碰撞而引起的。但經了解機床的行程限位開關沒有問題,用戶也沒有這方面的意見反饋。

　　3. Machine tool travel overtravel, worktable collision, resulting in accuracy damage. Overtravel during machine tool operation can easily lead to machine tool collision. But after investigation, it was found that there is no problem with the travel limit switch of the machine tool, and the user has not provided any feedback in this regard.

　　4.檢測方法不正確,導致精度超差　　檢驗員采用千分表配合磁力表座,以工作臺直線導軌滑座為檢測基準進行檢測,檢測方法及檢測基準也符合要求。　　5.裝配工藝不正確,造成裝配誤差

　　4. The detection method was incorrect, resulting in the accuracy exceeding the tolerance. The inspector used a dial gauge in conjunction with a magnetic gauge holder to perform the detection based on the workbench linear guide slide seat. The detection method and benchmark also met the requirements. 5. Incorrect assembly process leading to assembly errors

　　原裝配步驟是:先裝好直線導軌,以直線導軌的滑座為基準校正絲杠,再以絲杠兩端支承座安裝孔配作固定螺紋孔。用螺釘固定絲杠后,用磁力表座將千分表固定在直線導軌滑座上,測量絲杠、側母線和絲杠徑向跳動量,保證絲杠的平行度及跳動量在要求范圍內。

　　The original assembly steps are: first install the linear guide rail, calibrate the lead screw based on the sliding seat of the linear guide rail, and then match the mounting holes of the support seats at both ends of the lead screw as fixed threaded holes. After fixing the lead screw with screws, use a magnetic gauge holder to fix the dial gauge on the linear guide slide, measure the lead screw, side busbar, and radial runout of the lead screw, ensuring that the parallelism and runout of the lead screw are within the required range.

　　重新配作支承座定位錐銷,裝好錐銷后再復檢一次。裝配各步驟采用的處理方法基本正確,檢測基準與工藝基準也相符,檢測量具精度也能滿足要求,被測要素也正確。整個裝配過程沒有問題,但通過在現場觀察,發(fā)現裝配工藝中仍存在以下問題:

　　Reconfigure the supporting seat positioning cone pin, install the cone pin and recheck again. The processing methods used in each step of assembly are basically correct, the detection standards are consistent with the process standards, the accuracy of the detection measuring tools can also meet the requirements, and the measured elements are also correct. The entire assembly process was fine, but through on-site observation, it was found that there are still the following issues in the assembly process:

　　(1)使用手電鉆鉸孔時,由于鉸削余量較大,振動較厲害,雙手控制不穩(wěn),鉸刀擺動過大,造成錐孔鉸削后上大下小,錐度不是要求的1∶50。用涂色法進行檢查,發(fā)現錐銷與錐孔的接觸部位不正確,位置靠近小頭一端,不能保證良好的接觸精度,受到交變應力與振動時容易松動,從而導致定位精度下降。

　　(1) When using a handheld drill for reaming, due to the large reaming allowance and severe vibration, the control with both hands is unstable, and the reamer swings too much, resulting in a tapered hole that is not the required 1:50 after reaming. Using the coloring method for inspection, it was found that the contact area between the taper pin and the taper hole is incorrect, located near the small end, which cannot guarantee good contact accuracy. When subjected to alternating stress and vibration, it is easy to loosen, resulting in a decrease in positioning accuracy.

　　(2)機鉸后沒有留精鉸余量,也沒有進行手工精鉸。圓錐銷的配合都是依靠配合面的過盈產生摩擦力來定位的。由于機鉸后表面粗糙使實際過盈量減少,造成摩擦力不夠,自鎖性能下降,當受到交變應力與振動時容易松脫,從而導致定位精度下降。

　　(2) There is no margin left for precision hinges after machine hinges, nor is manual precision hinges performed. The fit of conical pins relies on the friction generated by the interference fit of the mating surface to locate them. Due to the rough surface of the machine hinge, the actual interference fit is reduced, resulting in insufficient friction and decreased self-locking performance. When subjected to alternating stress and vibration, it is easy to loosen, leading to a decrease in positioning accuracy.

　　(3)鉸孔時孔徑控制不嚴,鉸削過程中沒用錐銷試配,裝配時用銅棒輕輕敲入即可。由于不能保證足夠的過盈量,裝配后的摩擦力過小;受負荷及振動時易造成錐銷松動,失去定位作用,導致工作臺運動精度差。

　　(3) The aperture control during reaming is not strict, and no cone pin is used for trial fitting during the reaming process. During assembly, a copper rod can be gently tapped in. Due to the inability to ensure sufficient interference fit, the friction force after assembly is too low; When subjected to load and vibration, it is easy to cause the taper pin to loosen, lose its positioning function, and result in poor precision of the worktable movement.

　　(4)在鉆孔鉸孔等過程中,沒有進行防塵處理。雖然絲杠副帶有防塵圈,但鑄鐵粉塵非常細小,且出彩易粘附在絲杠表面。如有少量進入絲杠副傳動面,粉塵的研磨作用會加劇絲杠副的磨損,導致絲杠精度下降,降低使用壽命。

　　(4) During the drilling and reaming process, no dust prevention treatment was carried out. Although the screw pair is equipped with a dust ring, the cast iron dust is very fine and easily adheres to the surface of the screw. If a small amount enters the transmission surface of the screw pair, the grinding effect of dust will intensify the wear of the screw pair, resulting in a decrease in the accuracy of the screw and a reduction in its service life.

　　三、故障處理辦法

　　3、 Troubleshooting methods

　　1.使用機鉸粗鉸后建議留出精鉸余量,再手工精鉸　　這個方法可以糾正機鉸后的錐度誤差,降低孔壁的表面粗糙度值,提高配合面的接觸精度,保證足夠的摩擦力矩。

　　1. After using the machine hinge rough hinge, a margin for precision hinge must be left, and manual precision hinge can correct the taper error after machine hinge, reduce the surface roughness value of the hole wall, improve the contact accuracy of the mating surface, and ensure sufficient friction torque.

　　2.在鉸孔時應及時用錐銷試配　　目的是方便控制鉸孔孔徑。當錐銷能用手插入銷長的80%～85%左右時孔徑才為合格;清理鐵屑后,應在錐銷上涂機油后再用銅棒打入至與工件表面平齊,以保證足夠的摩擦力矩,防止在使用中受載荷而松動。

　　2. When reaming, a cone pin should be used in a timely manner for the purpose of easy control of the reaming hole diameter. When the taper pin can be manually inserted into about 80% to 85% of the pin length, the aperture is considered qualified; After cleaning the iron filings, oil should be applied to the taper pin and then driven with a copper rod until it is flush with the surface of the workpiece to ensure sufficient friction torque and prevent loosening under load during use.

　　3.做好絲杠表面的防塵處理　　在鉆孔、鉸孔及攻螺紋過程中,應作好絲杠表面的防塵處理。用清潔的布包裹住絲杠的外露部分,防止粉塵進入絲杠副傳動面,以延長精密元件的使用壽命,提高裝配精度。

　　3. Proper dust prevention treatment should be carried out on the surface of the screw during drilling, reaming, and threading processes. Wrap the exposed part of the screw with a clean cloth to prevent dust from entering the transmission surface of the screw pair, in order to extend the service life of precision components and improve assembly accuracy.

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