سختی سنج راکول دستی Mitech MHR-150A، بر اساس اصل مکانیکی الماس مخروطی یا فرورفتگی آلیاژی سخت با فشار دادن به سطح نمونه برای ایجاد فرورفتگی، اندازه گیری سختی مواد را با اندازه گیری عمق فرورفتگی درک می کند. با قابلیت بازرسی قطعات نهایی یا نیمه تمام نمونه ماشینکاری شده، برای تست سختی با دقت بالا برای قطعات دسته ای با مواد مختلف فلزی یا غیرفلزی مناسب است. طبق آمار، سختی سنجی راکول پرکاربردترین روش سختی سنجی در صنعت فرآوری فلزات است که نسبت بهره برداری آن بیش از 70 درصد است. با ظاهر جدید، عملکرد پایدار و خواندن بصری راحت صفحه کلاسیک، به طور گسترده در پردازش و ساخت فلز، تجزیه و تحلیل شکست مواد فلزی مختلف و زمینه‌های دیگر مانند کالج‌ها و موسسات تحقیقاتی استفاده می‌شود. ابزار سختی سنجی نوع جدید برینل برای آزمایش سختی موادی مانند چدن، فولاد، آلیاژ نرم و غیره است.
Function & application
l Used for quality control in metal processing manufacturing
l Used for failure analysis testing of metallic materials;
l Demonstration experiment for education and teaching in Colleges and Universities;
l Hardness testing of materials in scientific research institutions
Working Principle
The Rockwell hardness test is taking the diamond cone with 120°apex angle or the hardened steel ball with specified diameter as the indenter to press into sample surface with specific test force, then get the Rockwell hardness of the measured metallic materials according to the sample surface indentation depth.
The Rockwell hardness measurement principle is shown as below figure. 0-0 is the position that the diamond indenter is not yet in contact with the sample. 1-1 figure is the indenter position under the affect of the preliminary test force, the indentation depth is h1. The preliminary test is to eliminate the influence to the testing result accuracy caused by the roughness of the sample surface. 2-2 in the figure is the indenter position under the influence of the testing force (the preliminary test force and the main test force). The depth is h2. 3-3 in the figure is the indenter position after dismounting the main test force. As the metal elasticity will recovery some degree after deformation, the really indentation depth of the indenter is h3. The plastic deformation caused by the main test force make the indenter pressing into the depth is h＝h3－h1. Rockwell hardness value is determined by the size of h, the greater the depth h, the lower the hardness, otherwise, the higher the hardness.
In the traditional concept, usually use a constant C minus h to represent the level of hardness, while the depth of indentation per 0.002mm as a unit of hardness. The hardness value obtained is called the Rockwell hardness value, denoted by the symbol HR.
In the formula, c is a constant (for HRC, HRA, c is 0.2; for HRB, c is 0.26). The Rockwell hardness value HR obtained is an unknown number which is usually read directly on the test machine indicator when testing.
It should be noted that the measured hardness values would be different with different indenter and test force. Therefore, the Rockwell hardness testing specifies 15 different hardness test scales according to the different indenter specification and test force sizes. And the HRB, HRC, HRA are the most widely used.
Working Conditions
l Operation Temperature：10～30℃；
l Relative Humidity：≤65％；
l The surrounding environment should avoid of vibration, strong magnetic field, corrosive medium and heavy dust.
Instrument Features
l Widely used for high-precision hardness testing for parts with a variety of metal and non-metallic materials,
l Using the classic design of mechanical and manual device, data reading intuitive and convenient, without external power
supply, performance stable and reliable;
l Option for various specifications of the indenter, support 15 types of Rockwell hardness scales testing.
l With diamond indenter, durable and wear-resistance, the measurement is accurate. accurate measurement;
l Consistent with GB/T230.1, GB/T230.2, JJG112, GB/T230.2, ISO 6508-2, ASTM, E18 and other related domestic and
foreign standards.
Operating Method and Attentions
Instrument Maintenance
l During testing, to ensure accuracy, please make sure the distance between the adjacent indentation center and the
distance from the indentation center to edge of the specimen is greater than 3mm.
l Normally, the first point is only used to offset the gap of each support surface without needing to record the test result.
Record the statistical test result from the second point.
l Screw protective cover is designed to protect the screw from dust invasion. When instrument idle or test specimen height
less than 100 mm, it should be set on the outside of the screw. For testing the specimen with height above 100mm, it
should be taken out for normal use.
l It is strictly prohibited to turn the variable loading handwheel when the instrument load or unload the test force. Rotating
the handwheel forcibly will cause the internal gear dislocation, test force in chaos and even damage the internal parts of
the instrument
l If the specimen has visible deformation marks on the back and edges, the test result would be useless. It should choose
the intender or test force to test again.
l The test personnel shall strictly observe the operating procedures. Please use the standard blocks often to calibrate the
instrument before and after testing.
l Pay attention to palm the instrument for carrying to forbid falling across. Please fix well the measuring lever,
counterweight and boom before carrying.
l When not in use for a long time, please cover the dust cover to prevent dust into the instrument interior. And the
hardness block, indenter should be coated with antirust oil to prevent rusting after using.
l Please regularly put a small amount of oil on the screw and the handwheel interface
l The hardness tester should be calibrated at least once a year to ensure its accuracy.
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