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硬度計|力傳感器閉環系統Closed loop sys/雙語 簡介
INNOVATEST軼諾致力于設計和制造傳感器閉環控制加載的硬度計。為了更好地理解閉環系統相對于砝碼式系統的*性，我們必須弄清楚兩種系統的區別所在。
力傳感器-閉環系統
在工業化初期，測量機械結構的試驗力至關重要。大約在1940年，一種應變式稱重傳感器被發明出來。用于測量試驗力并將該力值以電信號形式輸出的力傳感器，大部分使用應變片來將材料變形/力轉換成電信號。
19世紀50年代，力傳感器應用于拉伸和壓縮試驗機。力傳感器理想的安裝位置，是在與工件的連接處的前端或盡量靠近的區域。電子系統利用反饋信號來調節加載裝置，進而得到設定的試驗力。
基于閉環系統的*性能，如今，所有電子拉伸壓縮試驗機都只采用閉環控制。閉環系統可以連續測量加載試驗力，且閉環系統中使用的組件比砝碼式要簡單得多。正如上文提到的砝碼式系統，為確保運行正常，砝碼式系統要求杠桿、軸點和零部件間的摩擦（相互配合）。
對于一臺硬度計，壓頭是測試系統與樣品接觸的一部分，它是獲得正確硬度值最重要的一個因素。為了消除結構缺陷的影響，機械方面的移動或其他干擾都會影響試驗力，因此力傳感器需與壓頭盡可能靠近。
只有這樣，基于力傳感器的優勢，閉環系統才能獲得較高的試驗力精度。如將力傳感器安裝在硬度計其他位置，它相對于傳統砝碼式系統的優勢將不復存在。
作為機器的核心，INNOVATEST工程師已設計出*的非商業的力傳感器和反饋系統。幾乎所有的INNOVATEST硬度計的壓頭都安裝在適合試驗力測試的位置，并保證了閉環技術的優勢。
閉環系統的優勢：
高精度試驗力
力反饋系統確保加載試驗力的準確性
寬泛的試驗力且不受限于機械結構
簡便的測試流程
對比砝碼系統，簡化機械結構
簡單的校正程序
閉環系統的缺點:
對比砝碼系統，價格更貴
需要供電系統
INNOVATEST designs and manufactures, primarily, load cell based, closed loop hardness testing machines. To understand the great advantages of the closed loop systems over dead weight systems, particularly in hardness testers, one should understand the difference between both systems.
LOAD CELL – CLOSED LOOP SYSTEMS
Measuring force in mechanical constructions became important in the early days of industrialization. Around 1940, a Strain gauge load cell was invented. A load cell is a transducer (sensor) that measures force, and outputs this force as an electrical signal. Most load cells use a strain gauge to turn material deformation/force in to an electric signal.
During the 1950s, load cells where implemented in tensile & compression testing machines. The load cell would most ideally be mounted just before or as close as possible to the contact point with the workpiece. The electronic system is designed to use the feedback to adjust the force application mechanism (motor) to apply only the desired force. Closed-loop systems work so well that today all electronic tensile/compression instruments exclusively use closed-loop control.A closed-loop system can constantly measure the test force being applied, and also the components used in a closed-loop system inherently lend themselves to a much simpler design than a dead-weight system. As mentioned on the DEAD WEIGHT systems page, dead-weight systems require levers, pivots and other friction-inducing components to function efficiently.
In a hardness tester, the indenter, the only part of the force system in contact with the test sample is the most important element for a correct hardness measurement. To eliminate the effect of mechanical imperfection, mechanical moving or other disturbance that could affect the test force, the load cell should be installed as close as possible to the indenter.
Only in this way the real advantage of load cell based, closed loop systems come to their maximum force accuracy. Load cells placed on other positions in the hardness testers mechanical force actuator, rapidly lose most of their advantage over traditional dead weight systems.
INNOVATEST engineers have designed unique non-commercial load cells and force application systems that are the heart of each machine. Nearly all INNOVATEST hardness testers measure force at the indenter mount location to assure the maximum benefits of closed loop technology.
Advantages of closed loop system:
High accurate test forces
Force feedback assures correct force is applied
Wide range of test forces not depending on mechanical limitations
Faster test procedures
Reduction of mechanical parts comparing to dead weight systems
Simple electronic calibration procedure
Disadvantages of a closed loop system:
More expensive than a dead weight system
Requires electricity