原文:
本文介绍了一套新研制的扩散真空泵性能的自动测试系统。该系统可以按照国家标准规定的方法自动检测扩散真空泵的极限压力和抽速。系统利用自主开发的光电液位检测方法和元件实现滴管液位的自动读取和记时;利用步进电机驱动针阀实现气体流量和测试罩内压力的自动调节;使用上位PC机和下位单片机的双级控制系统实现对整个测试系统和测试过程的自动控制。
作为应用最广的高真空抽气设备,油扩散泵在国内的生产、研究方面已达到相当的技术水平和一定的生产规模,被广泛应用于机械、电子、冶金、原子能、空间模拟等工业领域和科学技术研究中,为我国的科技发展做出了显著的贡献。近几年来,国内扩散泵产品从外观、功能到性能都有了较大的进展。
相对于扩散泵的生产企业数量和生产总量来说,国内扩散泵在产品性能检测方面还相对落后。目前很多企业尚没有自己的性能测试系统,对泵产品在出厂前的性能指标缺乏实际检测。国内现有的相关检测系统都采用全手动操作方式,对操作人员有较高的专业知识和实验技能要求,需经过专门培训才能胜任此项工作,而且测试数据精度受许多人为因素的影响,这些都为生产厂家自己独立开展扩散泵性能测试增加了难度。
针对这一现状,本文研制了一套扩散真空泵性能的自动测试系统。下面将就该系统的测试原理、系统的硬件与软件构成、研制过程所遇到的技术难点和解决措施作以介绍。
1、自动测试系统的测试原理
该套测试系统对扩散泵的极限压力和不同入口压力下的抽速曲线的测试原理与方法,xx参照相关国家标准的规定执行。其中扩散泵抽速曲线的自动检测,采用“定压法”原理测试。对应每一个测压点的测试步骤是:在工作阀开启的条件下,利用针阀调节充入测试罩的气体流量Q,使测试罩内的平衡压力p稳定在预期的压力值附近;关闭工作阀,依次记录滴管内液柱到达液位高度h1和h2的时间t1和t2;通过计算液柱净升高度h=h2-h1和上升所需时间t=(t2-t1),利用下式求得对应压力下的体积流率,即抽速。
S=Q/P=Kh/Pt
式中S???被测真空泵抽气速率,L/s
Q???流过泵口的气体流量,Pa?L/s
p???测试罩内规定位置的平衡压力,Pa
h???滴管内液柱上升净高度,mm
t???滴管内液柱上升所需时间,s
K???滴管函数,Pa?L/mm。
根据上述公式可知:要想计算出抽速S,需要已知对应测压点的K、h、p和t。其中,滴管函数K可以根据不同的滴管和连接管道尺寸,结合实际的测试工况事先计算出来;因此,实际需要读取的只有测试罩指定位置平衡压力p、滴管内液柱净升高度h和液柱净升高度h所需时间t三个量。该套测试系统所具有的自动测试功能,主要是指工作阀采用电磁阀自动开启关闭;针阀完成流量调节的过程采用步进电机驱动,并根据罩内实测压力与预设压力的对比进行反馈控制;利用光电液位开关测定滴管内液位到达设定位置h1和h2高度处的时间t1和t2。整个测试过程,以及之后的抽速计算、结果输出工作,均由计算机自动控制完成,只是在更换滴管和连接管路的过程中需要操作人员手工作业。
2、自动测试系统的硬件构成
2.1、机械部分构成
该测试系统机械部分的主体设计方案基于国家标准的详细规定。其结构如图1所示,主要由测试罩、提升机构、前级阀、预抽阀、工作阀、放气阀、微调阀、滴管、光电液位开关、贮液槽、台车和真空管路等组成,被测主泵为K-200型油扩散泵,前级为2X-4型旋片泵。
考虑到该实验台的主要用途是服务于东北大学过程装备与控制工程专业本科生的真空实验教学,所以在结构和功能上有所改动、扩展。对应K-200型油扩散泵,本应选用直径为200mm的测试罩,但考虑其它教学实验用途,
本系统使用了直径为400mm的测试罩,中间加装锥形过渡接口和插板阀与被测扩散泵相连。这些会导致管道流导的增加,从而使泵的抽速测定值降低,但不影响测试系统的工作原理和使用方法。在测试罩上还留有两个真空规管接口、一个前级阀接口、一个微调阀进气口、顶端留有放气口,以及连接其他真空测试仪器的两个备用接口。提升机构可以将测试罩提起,方便主泵的更换和其它教学实验的完成。考虑到要实现自动控制,所有的阀门均选择电磁驱动。此外,根据实验需要,还专门订制了内径分别为1.5、3、5、10、20、30、50mm的一系列滴管。
“Diffusion vacuum pump performance automatic test system ”是由提供的国际水泵新闻,译文仅供参考。另外,中国化工泵网还提供相关产品搜索:、、、、等。
译文:
This paper describes a newly developed diffusion vacuum pump performance of the automatic test system. The system can be provided in accordance with national standard method of automatic detection limit of diffusion vacuum pump pressure and pumping speed. System using self-developed optical liquid level detection method and device level to achieve the automatic dropper when read and recorded; use stepper motor needle to achieve gas flow and pressure test cap, the automatic adjustment; use of upper and lower PC, single chip two-stage control system for the entire test system and test process automation.
As the most widely used high-vacuum pumping equipment, oil diffusion pumps in domestic production, research, technology has reached a considerable level and a certain scale of production, is widely used in machinery, electronics, metallurgy, nuclear, space simulation, and industrial areas and scientific and technological research, technological development of our country has made significant contributions. In recent years, the domestic diffusion pump products from the appearance and function to performance have made great progress.
Production relative to the diffusion pump is the total number of enterprises and production, the domestic diffusion pump performance testing aspects of the product are relatively backward. At present, many enterprises still do not own performance test systems, on the pump performance in the factory before the lack of actual testing. Detection of the existing relevant national systems use full manual mode of operation, the operator had a higher knowledge and experimental skills required, required to undergo special training before doing the work, and test data accuracy is affected by many human factors, such both for the manufacturers to carry out their own independent diffusion pump performance test more difficult.
In response to this situation, the paper developed a diffusion vacuum pump performance of the automatic test system. The following principles will be a test of the system, hardware and software, the development process of the technical difficulties encountered and solutions made to introduce.
1, automatic test system testing principle
The test system set limits on the diffusion pump inlet pressure under different pressure and pumping speed curve of the testing principle and method, strictly in accordance with the provisions of the relevant national standards. Which diffusion pumping speed curve of automatic detection, a "constant pressure method" theory test. Measurement points corresponding to each of the test steps are: valve open in the work conditions, use of adjustment of the needle cover charge into the test gas flow rate Q, to cover the balance of the pressure test p value of stability in the vicinity of the expected pressure; close work valve, and then click inside the liquid column to reach record level dropper height h1 and h2 of the time t1 and t2; liquid column by calculating the net lift height h = h2-h1 and the rise time t = (t2-t1), using the following formula requirements may correspond to the volume flow rate under pressure, or pumping speed.
S = Q / P = Kh / Pt
Type in the S --- measured vacuum pumping speed, L / s
Q --- I pump the gas flow through the flow, Pa ? L / s
p --- tests cover the balance of pressure within the location provided, Pa
h --- dropper rise in net fluid column height, mm
t --- dropper rise time within the liquid column, s
K --- dropper function, Pa ? L / mm.
Based on the above formula indicates: To calculate the pumping speed S, the corresponding measurement points need to known the K, h, p and t. Where the function K can dropper dropper and connecting pipes of different sizes, combined with the actual test conditions calculated in advance; Therefore, the actual need to read the test covers only the specified location equilibrium pressure p, dropper rise within the liquid column height of the net h and the liquid column height h net rise time t 3 the amount. The test system has a set of automatic test function, mainly refers to the use of solenoid valves work automatically open and close; needle to complete the process of flow adjustment driven by a stepping motor, and the pressure under the hood measured compared with the pre-pressure feedback control; measured using optical liquid level switches liquid level reaches the set position within the dropper h1 and h2 height of the time t1 and t2. The entire testing process, and after the pumping speed calculation, output work, completed by computer control, just replace the dropper and the process of connecting pipeline operator manual needed.
2, automatic test system hardware configuration
2.1, machine parts
The test system of the mechanical parts of the main design criteria based on the detailed provisions of the State. The structure shown in Figure 1, mainly by the test mask, lifting mechanism, the front valve, pre-pumping valve, working valve, release valve, valve trim, dropper, optical level switches, storage sump, trolleys and vacuum tubes Road, etc, measured as the K-200 main pump-type oil diffusion pump, the front for the 2X-4 type rotary vane pump.
Taking into account the main purpose of the test bed is a service of Northeastern University, Process Equipment and Control Engineering undergraduate vacuum experimental teaching, so some changes to the structure and function, expansion. Corresponds to K-200 type oil diffusion pump, 200mm in diameter should be used in this test cover, but considering the use of other teaching experiment, the system uses 400mm diameter test cover, install the middle of the transition cone interface and flapper valves and are measured diffusion pump is connected. These will lead to the increase in pipe flow conductance, so that the pump's pumping speed measured values decrease, but does not affect the testing system works and use. In the test cast also left two vacuum gauge interface, a former grade valve interface, a fine-tuning the inlet valve, the top left gas discharge port, and connect the other two spare vacuum test equipment interfaces. Enhance the body can bring the test cover to facilitate the replacement of the main pump and other teaching was accomplished. Taking into account to achieve automatic control, all the valves are selected electromagnetic drive. Moreover, according to experimental needs, specially ordered the 1.5,3,5,10,20,30,50 mm diameter were a series of dropper.