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Method for detecting residual stress for high-molecular injection molding processing

A residual stress, injection molding technology, applied in the direction of measuring force, measuring device, instrument, etc.

Inactive Publication Date: 2013-01-02
HENAN UNIVERSITY OF TECHNOLOGY
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0003]Stress release method, on the one hand, additional stress will be generated when removing materials from polymer materials, and on the other hand, it will change the structure of the polymer during processing , so that the stress distribution state changes, resulting in large measurement errors
As for the physical detection method, its disadvantage is that the measurement material must meet certain optical performance requirements, and the types of measurement materials are limited.
Second, the measurement results are greatly affected by the test environment and test conditions, and the test accuracy is not easy to guarantee

Method used

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  • Method for detecting residual stress for high-molecular injection molding processing
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  • Method for detecting residual stress for high-molecular injection molding processing

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0066] In this embodiment, the residual stress of the polypropylene injection molded part along the injection flow direction is measured. The sample 5 of the injection molded part has a length of 180mm, a width of 40mm, and a thickness of 3mm. The specific measurement steps are as follows:

[0067] Step 1: Making the Stress Sensor

[0068] Such as figure 1As shown, electrode lead wires 2 are arranged at both ends of the conductive fiber 1, and the conductive fiber 1 and the electrode lead wires 2 at both ends constitute a stress sensor. The conductive fiber 1 is a conductive fiber deposited with polyaniline on the surface.

[0069] Step 2: Clamping

[0070] Such as figure 2 As shown, punch a hole on the movable template 3 of the injection mold, then set the rubber sleeve in the hole, pre-install the assembled stress sensor in the movable mold cavity of the injection mold, and connect the electrode lead wire 2 through the rubber sleeve fixed, thereby fixing the stress sen...

Embodiment 2

[0102] Repeat Example 1 with the following differences. In this example, the residual stress of the polycarbonate injection molded part is measured, and the glass transition temperature of polycarbonate is 150°C.

[0103] Step 2: Clamping

[0104] The stress sensor is arranged along the length direction of the polycarbonate injection molded part and installed at 0.1mm in the thickness direction of the cavity.

[0105] Step Six: Heat Treatment

[0106] Heat the polycarbonate injection molded parts to 100°C and then anneal for 4 hours,

[0107] The measurement and calculation results are shown in Table 2.

[0108] Table 2: Measurement of fiber resistivity change and residual stress calculation results of six polycarbonate samples

[0109] Fiber resistivity before annealing Fiber resistivity after annealing treatment Change rate (%) strain(%) Residual stress (MPa) 3.656 3.608 -1.31 -0.326 6.84 3.666 3.615 -1.39 -0.345 7.24 3....

Embodiment 3

[0112] Repeat Example 2 with the following differences. In this example, the residual stress of the ABS injection molded part is measured, and the glass transition temperature of ABS is 90°C. In the heat treatment, the ABS injection molded part is heated to 100°C, and then annealed for 4 hours.

[0113] Step Eight: Stress Calculation

[0114] Since ABS is an amorphous material whose glass transition temperature is lower than the heat treatment temperature, in order to improve the calculation accuracy, ABS is considered to be in a viscoelastic state, and the corresponding residual stress of polymer injection molded parts is:

[0115]

[0116]

[0117] In the formula,

[0118] - is the calculated stress;

[0119] - is the elastic modulus of ABS;

[0120] - is the Poisson's ratio of ABS;

[0121] , - is the strain in the length direction and width direction of the ABS injection molded part;

[0122] - is the magnitude of creep generated during heat treatmen...

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Abstract

The invention relates to a method for detecting residual stress for high-molecular injection molding processing. The method comprises the following steps of: performing injection-molding and processing conductive fiber subjected to modification treatment and a high-molecular material; arranging electrode lead-out wires at two ends of the conductive fiber; performing thermal treatment on an injection-molding product; measuring resistance of the conductive fiber before and after the thermal treatment on the injection-molding product; and converting the corresponding residual stress of the injection-molding product by the change of the resistance of the conductive fiber. By utilizing the method, the residual stress formed in the processing process of the different parts of the injection-molding product can be accurately measured, and a basis is provided for researching high-molecular new materials, new techniques and optimization design of moulds.

Description

Technical field: [0001] The invention belongs to the technical field of injection molding processing of polymer materials, and in particular relates to a detection method for residual stress of injection molding processing of polymer materials. Background technique: [0002] At present, there are mainly two types of testing methods for residual stress in injection molding of polymer materials: mechanical testing methods and physical testing methods. Mechanical detection methods mainly include peeling method, drilling method and so on. Use mechanical processing methods (such as drilling, etc.) to cause corresponding displacements and strains due to the release of part of the stress, measure these displacements or strains, and convert them to get the original stress at the processing part of the component. Therefore, this test method is also called stress relief method. The advantage of this method is that it is convenient and easy to implement, and it has better adaptabil...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01L1/22
Inventor 吴海宏蔡刚毅张保丰蒋爱云赵振峰郭正民畅同晨
Owner HENAN UNIVERSITY OF TECHNOLOGY
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