Positive extrusion test method for plastic forming friction coefficient and friction factor

A friction coefficient and friction factor technology, which is applied in the field of plastic forming friction coefficient and friction factor testing, can solve the problems of difficulty in accurately determining the position of the neutral plane, accurate measurement data, few practical applications, and inconvenient operation. Easy to operate and easy to process

Inactive Publication Date: 2013-09-04

CHONGQING UNIV

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Problems solved by technology

The main problem of this method is that it is difficult to accurately determine the position of the neutral plane and accurately measure the data, so there are few practical applications

[0015] In view of the problems of large errors and i...

Abstract

The invention relates to a positive extrusion test method for a plastic forming friction coefficient and a friction factor. The positive extrusion test method comprises the following steps of 1) preparing a tensile specimen by using a to-be-tested material and measuring a yield stress Y at a to-be-tested temperature; 2) preparing a cone-shaped mold with a cone angle [theta] and the diameter of a large end port and a small end port being D0 and D respectively, by using the same material to the to-be-tested mold; 3) preparing a cylinder specimen with the diameter of d by using the to-be-tested material, wherein d value is between D0 and Dl; 4) extruding a specimen coated by a lubricating agent downward in the cone-shaped mold on a material testing machine at a constant speed and recording a value when extrusion load F starts to be stable; 5) calculating the friction coefficient and the friction factor according to formulas disclosed by the invention; and 6) repeating the above steps for 3-5 times, and taking an average value as a result. The positive extrusion test method is in no need of measuring geometrical shapes after a test specimen is deformed, has no abnormal deformations such as compressive instability and the like, is simple in specimen process and needs no theoretical calibration curve. Besides, the positive extrusion test method has high test precision, convenient operation and high efficiency, and can be used for tests at various temperatures and speed conditions.

Application Domain

Using mechanical meansMaterial analysis

Technology Topic

Calibration curveInstability +8

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Examples

Experimental program(1)

Example Embodiment

[0030] In the following, specific embodiments of the present invention will be described by taking the determination of the friction coefficient and friction factor during the thermoplastic forming process of AZ31 magnesium alloy at 200° C. and the plastic forming process of 1100 aluminum alloy at room temperature as an example.

[0031] In the embodiment, the mold material of the conical die is T10A, the diameter d of the cylinder blank of 1100 and AZ31 is 18mm, the height H is 40mm, the cone angle θ of the conical die is 30°, and the small port diameter D is 16mm .

[0032] (1) Determine the friction coefficient μ and friction factor m during hot forming of AZ31 magnesium alloy at 200℃

[0033] 1) Adopt the metal material high temperature tensile test standard (GB/T4338-1995), use the AZ31 material to be tested to make tensile test specimens, and measure the yield stress Y of the material at a temperature of 200°C. In this example, the measured value of Y is 105MPa;

[0034] 2) Use T10A material to make cone angle θ of 30°, large port diameter D 0 It is a tapered mold with 25mm and a small port diameter D of 16mm;

[0035] 3) Use AZ31 to make cylindrical samples, measure and record the diameter data d of each sample;

[0036] 4) Spread the lubricant to be tested evenly on the sample, squeeze the sample downwards in the conical mold at a constant speed of 0.1mm/s on the universal material testing machine, and read the extrusion load of the equipment. When the load F becomes stable, the recorded value is 10KN;

[0037] 5) Use formulas (1) and (2) to calculate μ and m;

[0038] 6) Repeat the test 3 times, get the μ and m of each time, and take the average value as the test result. In this example, the friction coefficient μ is 0.2 and the friction factor m is 0.35.

[0039] (2) Determine the friction coefficient μ and friction factor m of 1100 aluminum alloy plastic forming at room temperature

[0040] 1) Use the room temperature tensile test method for metallic materials (GB/T228-2002), use 1100 aluminum alloy material to make tensile test specimens, and measure the yield stress Y of the material at room temperature. The test value of this example is Y=15MPa;

[0041] 2) Use T10A material to make conical mold with the same size as before;

[0042] 3) Use 1100 aluminum alloy material to make cylindrical specimens with the same dimensions as before;

[0043] 4) Evenly spread the lubricant to be tested on the cylindrical sample, squeeze the sample downwards in the conical die at a constant speed of 1mm/s on the universal material testing machine, and read the extrusion load of the equipment, when the load F When it becomes stable, the recorded value is 1.4KN;

[0044] 5) Using formulas (1) and (2), calculate μ and m:

[0045] 6) Repeat the test 3 times, get the μ and m of each time, and take the average value as the test result. In this example, the friction coefficient μ is 0.26, and the friction factor m is 0.45.

[0046] The plastic finite element method is used to numerically simulate the above extrusion process. Under the same friction coefficient μ and friction factor m, the error between the extrusion load calculated by the numerical simulation and the extrusion load test value of the physical experiment is within 2%, indicating The friction coefficient (factor) tested by this method has high accuracy.

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Positive extrusion test method for plastic forming friction coefficient and friction factor

AI-Extracted Technical Summary

Problems solved by technology

Abstract

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Examples

Example Embodiment

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Description & Claims & Application Information

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