Device and test method for measuring left half part of sheet metal forming limit diagram
A forming limit diagram, the left half of the technology, applied in the direction of measuring devices, analysis materials, instruments, etc., can solve the problems of disconnection, invalid test, large drawing error of forming limit diagram, etc., to prevent movement, facilitate strain data, Ease of Measurable Effects
Inactive Publication Date: 2015-05-27
NANJING UNIV OF AERONAUTICS & ASTRONAUTICS
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[0005] The above two methods both use the force attenuation method or human eye observation when judging the fracture of the sample. However, it is difficult to control the critical state of the sample just necked down or just cracked just by human eyes. It will be broken directly and the position of the sample rupture is often at the hole of the die and near the drawing bead, which causes a large error in the drawing of the subsequent forming limit diagram and even invalidates the test
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[0024] The present invention will be described in further detail below in conjunction with the accompanying drawings.
[0025] Such as image 3 and 4 As shown, the device for determining the left half of the sheet metal forming limit diagram in the present invention includes two sample fixing mechanisms and a sample jacking mechanism. Two sample fixing mechanisms are arranged on both sides of the sample jacking mechanism. The sample jacking mechanism includes a cylindrical roller 2, a central rotating shaft 3, a bracket 4 and a hydraulic pump 7. The central rotating shaft 3 passes through the cylindrical roller 2, and the cylindrical roller 2 can rotate freely around the central rotating shaft 3. The two ends of the central rotating shaft 3 Supported on the bracket 4, the bottom of the bracket 4 is connected with the hydraulic pump 7, and the hydraulic pump 7 drives the cylindrical roller 2 to move up and down through the bracket 4. The sample fixing mechanism includes a di...
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The invention discloses a device for measuring the left half part of a sheet metal forming limit diagram, belonging to the field of sheet metal forming. The device comprises two sample fixing mechanisms and a sample jacking mechanism, wherein the two sample fixing mechanisms are respectively arranged at the two sides of the sample jacking mechanism; the sample jacking mechanism comprises a cylindrical roller wheel and a lifting device; the cylindrical roller wheel is erected above the lifting device; the lifting device is used for driving the cylindrical roller wheel to move up and down. The two ends of a sample crack or are directly broken by enabling the cylindrical roller wheel to gradually go up, one end of the sample generally cracks or is broken in advance, and the other end of the sample is just in a critical state of just necking down or just cracking, so that the problem that the critical state of just necking down or just cracking of the sample is difficult to control can be solved; after that, the strain of the area is measured, so that the left half part of the strain limit diagram can be more accurately drawn. The invention also discloses a test method for measuring the left half part of the sheet metal forming limit diagram.
Description
technical field [0001] The invention relates to a measuring device and method for a forming limit diagram, in particular to a device and a method for measuring the left half of a forming limit diagram of a sheet metal, belonging to the field of sheet metal forming. Background technique [0002] The forming limit of sheet metal refers to the ultimate strain in the process of metal plastic deformation. The existing methods for measuring the forming limit diagram are all carried out on a common plate formability testing machine by using a spherical or cylindrical punch. The purpose of the bone-shaped sample used in the sample is to break the sheet in the middle, so as to facilitate observation and obtain the required strain path, such as figure 1 shown. [0003] However, in the actual experiment process, such as figure 2 As shown, when using a hemispherical punch to form the sheet to obtain the forming limit diagram, due to the large compressive stress between the sheet and...
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IPC IPC(8): G01N3/307G01B21/32
Inventor 王辉张成祥陈天明
Owner NANJING UNIV OF AERONAUTICS & ASTRONAUTICS