CN103499578A - Detection method of residual stress - Google Patents
Detection method of residual stress Download PDFInfo
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- CN103499578A CN103499578A CN201310429633.XA CN201310429633A CN103499578A CN 103499578 A CN103499578 A CN 103499578A CN 201310429633 A CN201310429633 A CN 201310429633A CN 103499578 A CN103499578 A CN 103499578A
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Abstract
The invention discloses a detection method of residual stress, and particularly relates to detection on a plastics product. The detection method comprises the steps of immersing a product to be detected in a corrosion solution, and taking the product to be detected out and detecting whether a residual stress reaction occurs when the immersing time reaches an immersing time set value, wherein if the residual stress reaction does not occur, the product to be detected is qualified. The corrosion solution can be prepared by mixing carbon tetrachloride and normal octane according to the volume ratio of 1:1, or by mixing methylbenzene and normal propyl alcohol according to the volume ratio of 1:3; the immersing time is obtained by processing immersing time within which the stress reaction occurs during pre-detection on products in the same batch, and under the residual stress reaction, the surface of a plastic product cracks or powdery particulate materials are formed on the surface of the plastic product due to corrosion.
Description
Technical field
The present invention relates to fields of measurement, relate in particular to a kind of detection method of unrelieved stress.
Background technology
In the engineering plastics injection moulding process, melt in mold filling, pressure maintaining period, melt flows produced flow stress and molecular orientation and in cooling procedure goods internal and external temperature skewness, expand with heat and contract with cold and receive restriction, simultaneously through being heated and the effect of power, thereby produce unrelieved stress.And, in the use of injection-molded item, temperature, humidity, be heated etc. all can be brought out unrelieved stress and be discharged.This stress relief slowly can cause the goods position to produce fine crack, has not only reduced physical strength, causes in addition the risk of local accelerated oxidation, finally may cause the injection-molded item disabler.Need the detection of injection-molded item being carried out to unrelieved stress can meet the use needs with the judgement product for this reason, also judge that whether goods are qualified.
Traditional residual stress test method can be divided into two classes: a class is that machinery discharges mensuration, as boring method, peeling method, Method of Stress Relaxation, hardness method; One class is the nondestructive measurement method, as birefringent light method, X-ray diffraction method, supercritical ultrasonics technology, Electronic Speckle Pattern Interferometry.For plastics, above traditional method of testing exists that tested material character or physical dimension etc. can't meet test request, the test duration is long, testing apparatus is expensive, the tester requires the problems such as high, and these problems especially highlight under some need the scene of a large amount of tests and tested object---being tested as the PC the most frequently used to mobile phone products (polycarbonate polycarbonate) structural member---of a great variety.
Summary of the invention
The problem existed for plastic products unrelieved stress detection method in prior art, the object of the invention is to propose a kind of detection method one of to address the above problem at least.
Technical solution of the present invention is achieved in that
Immerse in corrosion solution by tested goods and start timing; Took out tested goods when the immersion time, setting value reached; Whether have unrelieved stress reaction, if can't detect for qualified if detecting tested product surface.
Further, described unrelieved stress reaction is ftractureed for tested product surface or forms Powdered shot-like particle because of corrosion on surface.
Further, described immersion time setting value preparation method is: the tested goods of same production batch are immersed respectively to described corrosion solution, and the immersion time value of the tested goods of described unrelieved stress reaction appears in record; Time value to gained, calculate mean value after removing a maximal value and a minimum value, and remove after maximal value and minimum value the fiducial interval that calculates variance, then by the fiducial interval upper limit addition of mean value and variance, sum is immersion time setting value.
Further, describedly occur that the quantity of the tested goods of unrelieved stress reaction is no less than 5.
Further, described corrosion solution is that phenixin and normal octane mix in 1: 1 by volume or toluene and n-propanol mix in 1: 3 by volume.
Further, described corrosion solution quality is pure for analyzing.
Further, whether the tested product surface of described detection has the method for unrelieved stress reflection to be: open hole detection or magnifier detect or 10 power microscopes detect.
Further, before whether the step of unrelieved stress reaction is arranged at the tested product surface of described detection, also comprise the residual corrosion solution of removing on tested goods the step of drying.
Further, tested goods adopt the mode mounted to immerse described corrosion solution.
Further, tested goods be submerged in described corrosion solution and make the top of tested goods and the solution face of corrosion solution at a distance of 0.5 to 1 centimetre.
Adopt technical scheme of the present invention, compared with prior art: can effectively solve the problem that the various test condition caused of plastic products sample class can't be satisfied, as long as it is enough large to hold the container of tested object; Test duration is short, only needs to adjust corrosion solution and gets final product to change corrosion speed; Testing apparatus is cheap and be easy to preparation, is very suitable for requiring the occasion of quick test; The test effect is directly perceived, and accuracy rate can satisfy the demands, and for the tester, requires lowly, and training is simple, is applicable to online detection.
The accompanying drawing explanation
The proving installation structural drawing that Fig. 1 is embodiment.
Embodiment
Plastic products unrelieved stress test philosophy of the present invention is: the source of unrelieved stress is mainly be heated inequality and local pressures while ejecting of goods.Internal stress causes product surface microfissure and density variation to occur.Under the prerequisite that the corrosion agent that can dissolve, infiltrate plastics is arranged, residual stress distribution causes different positions with different speed generation corrosions, and impels internal stresses release.When unrelieved stress is excessive, release rate is when too fast, will occur that the goods stress discharges and fracture or by phenomenons such as serious corrosions.
Illustrate method of testing of the present invention below in conjunction with accompanying drawing.
(1) proportioning corrosion solution.The mixed solution of preparation phenixin and normal octane, by the mixing of 1: 1 by volume of this two kinds of solution; Theoretically, any have the solution of corrosion can be used as corrosion solution of the present invention to plastic products, other as toluene and the n-propanol mixed solution of 1: 3 by volume; It is pure that the quality of solution should be at least analysis, and analyzing pure is technical term, refers to that major component content is very high, purity is higher, disturbs impurity very low, is applicable to the solution of technical analysis and chemical experiment.
(2) lay container 1 and support 4.The solution prepared is contained in container; Mounting bracket above container, support is fixed with respect to container; Support is for hanging plastic products to be detected, for plastic products can all be immersed in solution, to avoid sample to float in solution or test surfaces is stopped, affect test result, adopted method of clamping that tested plastics are sent in solution, support adopts the inert material making in case corroded by solution, and inert material can be selected from glass or metal etc.; For fear of corrosive solution evaporation, container is to seal, and support is together enclosed among container.
(3) cleaning sample 3.The PC injection moulding bonnet that the sample of choosing is mobile phone, the cleaning sample surfaces is to the clean contamination-free of sample surfaces.In this process, observe for convenience sample surfaces, usually adopt 10 times of stereo microscopes; When the cleaning sample surfaces, can directly with filter paper or absorbent cotton, dab sample surfaces and get final product, or use the ear washing bulb air blast to blow off surperficial foul until sample surfaces is clean, for dirty tangible indelible can the letting slip in surface.
(4) hang and just soak.Sample is just hung and immersed in solution by support, and airtight container, the mixed solution liquid level is higher than the about 1cm in tested goods top; Guarantee that under this condition solution can immerse in the sample surfaces weak part, reaches the purpose of accurate test.
(5) after certain hour, take out.Detect and can be used for estimating roughly cracking time several times at first, with this, be defined as the take-off time of this step.
(6) remove raffinate, dry.Open airtight container, take out sample, with the residual solution on the ethanol cleaning article, the ethanol quality is that chemical pure gets final product, and after cleaning, goods is dried; Ethanol is selected chemical pure, and chemical pure is technical term, refers to that major component content is high, purity is higher, exists and disturbs impurity, is applicable to the solution of chemical experiment and synthetic preparation.
(7) observe stress response.Observe whether goods have face checking or, because the powdery granule thing appears in corrosion, if having, record the immersion time value this time; Do not get fresh sample and repeat above-mentioned detecting step; Obtain in order to improve the probability that effectively immerses time value, the roughly soak time can refer step (5) obtained.
(8) the gained time data is processed and obtained the soak time setting value.After the immersion time that obtains at least 5 tested goods that stress response occurs, obtained time data is processed, concrete for removing minimum value averaged of a maximal value; The fiducial interval of the variance of each lot data after calculating removal maximum/minimum; The fiducial interval upper limit sum of mean value and variance, be and detect the soak time setting value of this batch of goods unrelieved stress when whether qualified.
(9) to the goods unrelieved stress, whether qualified detection starts.Start formal product detecting step after obtaining the soak time setting value of these goods.
(10) repeat top step (1) to step (4) for tested goods.
(11) immersion is taken out tested goods, repeating step (6) after reaching setting value.
(12) observe tested goods, if there is stress response, be face checking or the powdery granule thing occur goods are defective, it is unqualified not occur.Can bore hole directly observe, also can use conventional magnifier to observe, as 3 to 5 times of magnifieres, also can use 10 power microscopes to be observed.
In the present embodiment, adopt the test result of method of testing of the present invention to show, there is larger stress response in described PC moulding at clamping part, consistent with the testing result according to ASTM E837-2001 method (the material technology standard " ASTM E837-2001 measures the standard test method of unrelieved stress with drilling strain gauge " that American Society Testing and Materials is fixed), illustrate that method of testing of the present invention has higher accuracy.Simultaneously, adopt method of testing of the present invention, its soak time setting value can be only a few minutes, thus the Real-Time Monitoring that carries out product quality that can be more quick, easy, safe.
These are only preferred embodiment of the present invention, be not intended to limit protection scope of the present invention, therefore, all any modifications of making within the spirit and principles in the present invention, be equal to replacement, improvement etc., within all should being included in protection scope of the present invention.
Claims (10)
1. the detection method of a unrelieved stress is characterized in that:
Immerse in corrosion solution by tested goods and start timing;
Took out tested goods when the immersion time, setting value reached;
Whether have unrelieved stress reaction, if can't detect for qualified if detecting tested product surface.
2. detection method according to claim 1 is characterized in that:
Described unrelieved stress reaction is for tested product surface cracking or form Powdered shot-like particle on surface because of corrosion.
3. detection method according to claim 2, is characterized in that, described immersion time setting value preparation method is:
The tested goods of same production batch are immersed respectively to described corrosion solution, and the immersion time value of the tested goods of described unrelieved stress reaction appears in record;
Immersion time value to gained, calculate mean value after removing a maximal value and a minimum value, and remove after maximal value and minimum value the fiducial interval that calculates variance, then by the fiducial interval upper limit addition of mean value and variance, sum is immersion time setting value.
4. detection method according to claim 3 is characterized in that:
Describedly occur that the quantity of the tested goods of unrelieved stress reaction is no less than 5.
5. corrosion solution according to claim 1 is characterized in that:
Described corrosion solution is that phenixin and normal octane mix in 1: 1 by volume, or toluene and n-propanol mix in 1: 3 by volume.
6. corrosion solution according to claim 5 is characterized in that:
Described corrosion solution quality is pure for analyzing.
7. detection method according to claim 1 and 2, is characterized in that, whether the tested product surface of described detection has the method for unrelieved stress reflection to be:
Open hole detection or magnifier detect or 10 power microscopes detect.
8. detection method according to claim 7 is characterized in that:
Before whether the step of unrelieved stress reaction is arranged at the tested product surface of described detection, also comprise the residual corrosion solution of removing on tested goods the step of drying.
9. detection method according to claim 1 is characterized in that:
Tested goods adopt the mode mounted to immerse described corrosion solution.
10. detection method according to claim 1 is characterized in that:
Tested goods be submerged in described corrosion solution and make the top of tested goods and the solution face of corrosion solution at a distance of 0.5 to 1 centimetre.
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| CN201310429633.XA CN103499578A (en) | 2013-09-10 | 2013-09-10 | Detection method of residual stress |
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Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104062039A (en) * | 2014-06-17 | 2014-09-24 | 双登集团股份有限公司 | Method for detecting storage battery plastic shell body residual stress in quantitative mode |
| CN104228013A (en) * | 2014-10-14 | 2014-12-24 | 深圳市东方亮彩精密技术有限公司 | Internal stress soaking testing machine of plastic product |
| CN111044192A (en) * | 2019-11-29 | 2020-04-21 | 安徽高德铝业有限公司 | Residual stress detection method for aluminum product |
| CN113092349A (en) * | 2021-03-31 | 2021-07-09 | 东风汽车集团股份有限公司 | Method for detecting stress cracking problem of polycarbonate automobile parts |
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| CN101975780A (en) * | 2010-04-28 | 2011-02-16 | 湖南农业大学 | Observation and density measurement method for glandular hairs on Artemisia annua leaf surfaces |
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Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104062039A (en) * | 2014-06-17 | 2014-09-24 | 双登集团股份有限公司 | Method for detecting storage battery plastic shell body residual stress in quantitative mode |
| CN104228013A (en) * | 2014-10-14 | 2014-12-24 | 深圳市东方亮彩精密技术有限公司 | Internal stress soaking testing machine of plastic product |
| CN104228013B (en) * | 2014-10-14 | 2016-08-24 | 深圳市东方亮彩精密技术有限公司 | Plastic internal stress Soak Test machine |
| CN111044192A (en) * | 2019-11-29 | 2020-04-21 | 安徽高德铝业有限公司 | Residual stress detection method for aluminum product |
| CN113092349A (en) * | 2021-03-31 | 2021-07-09 | 东风汽车集团股份有限公司 | Method for detecting stress cracking problem of polycarbonate automobile parts |
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