Đăng ký Đăng nhập
Trang chủ Kỹ thuật - Công nghệ Cơ khí chế tạo máy Ktf_6_prüfung und qualitätssicherung stbo...

Tài liệu Ktf_6_prüfung und qualitätssicherung stbo

.PDF
49
163
76

Mô tả:

Adhesive Manufacturing Processes Chapter 6: Testing and Quality Assurance Univ.-Prof. Dr.-Ing. Prof. h.c. Stefan Böhm Department for Cutting and Joining Manufacturing Processes (tff) University of Kassel, Germany Quelle: Wikipedia Agenda  Introduction  Destructive Testing Methods  Non-Destructive Testing Methods 2 Introduction  Testing & Quality Assurance is especially important  joined elements can either not be reworked or only with much effort  Criteria for the selection of a testing method for an adhesively joined bond: ● parameters that need to be examined ● destructive or non-destructive testing ● circumstances under which the test is to be carried out (i.e. production control or individual examination)  testing standards and regulations need to be followed Source: Habenicht 3 Introduction  Important aspects for the quality assurance for adhesive bonding: 1. Planning: – Training measures for employees, – Integration of the production of adhesively joined bonds into the construction phase, – Development of company-specific regulations or production standards, Source: Habenicht 4 Introduction 2. Adhesives: – Checking of the supplier´s specifications on the label to avoid confusion – For further identification of the adhesive, viscosity, density and, if necessary, solids content and colour should be examined  Checking of rheological characteristics (i.e. viscosity, thixotropy) – Checking of storing time and temperature – If necessary, execution of test samples and tests 3. Joint Elements: – Assessment of the surface quality (how clean, free of grease) – Testing of the wetting properties (water drop test) – Assessment of roughness – Required dimensions, tolerances Source: Habenicht 5 Introduction 4. Surface Treatment: – Blasting material (size of grains, free of grease (also the supply air) – Pureness of the degreasing material – Composition, concentration and temperature of the pickling and chemical pretreatment baths – Pureness of the rinsing baths 5. Application of the Adhesive: – Preparation of the adhesive – Degree of mixture and the relation of the components to each other – Pot life, amount, thickness of the layer, adhesive wetting – Checking if the system for the application, mixture and dosing functions properly – Positioning and fixation of the joint elements Source: Habenicht 6 Introduction 6. Environmental Conditions: – Cleanliness in the production halls – Temperature, if necessary, climatisation (adsorption of humidity at the surfaces) – Degree of humidity in the air 7. Occupational and Environmental Safety (Disposal, Recycling): – various legal standards, laws and guidelines 8. Documentation: – Continuous documentation of the parameters that are important for the quality Source: Habenicht 7 Introduction  Classification of the Testing Methods for Bonds Testing of the Bond Destructive Testing Static Source: Habenicht if necessary, inclusion of specific circumstances Dynamic Non-Destructuve Testing Highly Dynamic 8 Agenda  Introduction  Destructive Testing Methods  Non-Destructive Testing Methods 9 Destructive Testing Methods static short-term stress  Shear Stress: ● Shear Test – According to DIN EN 1465 (DIN 53283): „Determination of the shear strength of highly strong overlap bonds“ :Bond Strength, Fmax:Maximum Force, A: Bond Area) Source: Habenicht 10 Destructive Testing static short-term stress  Shear Stress: ● Disadvantages: – Influence of the expansion of the joint elements – Eccentric fixation – To avoid eccentric stress in testing machines, specimen reinforcement in the fixation area is done (out of the same specimen material) ● Field of Application: – Testing method serves to examine the usability and the quality of the adhesive: – When developing and applying the adhesive, – When controling the production to ensure the quality – When comparing adhesives under chemical and physical stress and influence Source: Habenicht 11 Destructive Testing static short-term stress  Tensile Stress: ● Shear Stress and Sliding Behaviour – „Thick“ shear test – Implementation according to ISO 11003-2 (before DIN 54451) – No bending moment  pure shear stress – Building elements quite thick  Expansion of joint elements is avoided Source: Habenicht 12 Destructive Testing static short-term stress  Torsion Shear Stress: ● Torsion Shear Stress – according to: ISO 10033-1 and ISO 11003-2 – Two pipe sections are twisted longitudinally in opposite directions – Advantage: very homogeneous distribution of the shear stress, eliminates shear and bending stress – Disadvantage: elaborate preparation of the specimen to ensure the concentricity of the hollow cylinder and the compliance to the defined thickness of the adhesive layer Source: Habenicht 13 Destructive Testing static short-term stress  Tensile Stress: ● according to DIN EN 26922 (DIN 53288) „determination of tensile strength“ ● stress under normal forces (this means horizontal to the joint surface) ● advantages: defined stress ratio and information about adhesion and cohesion behaviour of the bond Source: Habenicht 14 Destructive Testing static short-term stress  Compression Shear Stress: ● according to DIN 54452 ● determination of shear strength of adhesive rotationally symmetric bond gaps in axial direction ● especially for anaerobic adhesives for shaft-hub-connections ● advantages: homogeneous distribution of shear stress ( : shear strength, FB: breaking strength, A: shearing area, D: bolt diameter, l: case length) Source: Habenicht 15 Destructive Testing static short-term stresssche Kurzzeitbeanspruchungen  Torsion Stress: ● also mainly for anaerobic adhesives ● if the geometry is round, it can be tested flatly (1.) or with a thread (2.): 1. Torsion Strength – apply according to DIN 54455 „ Determination of shear strength of adhesives in a rotationally symmetric joint gap in tangential direction“ – ( : torsion shear strength, MB: measured ultimate moment, r: radius of the joint gap, A: shearing area) Source: Habenicht 16 Destructive Testing static short-term stress  Torsion Stress: ● if the geometry is round, it can be tested flatly (1.) or with a thread (2.): 2. Breakaway torque – according to DIN 54454  on adhesively joined threads (see picture) – serves to compare the security effect of bonded threads – the breakaway torque is ascertained from the rotational angle diagram MLB (relative motion between nut and screw) Source: Habenicht 17 Destructive Testing static short-term stress  Peel Stress: ● this stress must be avoided constructively  peeling stress is always the worst for a bond ● examination of adhesion behaviour ● line loads instead of area loading ● testing occurs under constant load or constant peel speed Simple peel stress Source: Habenicht 18 Destructive Testing static short-term stress  Peel Stress: ● Four methods for testing: 1. Angle Peel Test: – according to ISO 11339 and DIN EN 28510 „Determination of the resistance of metal bonds to peeling forces that occur horizontally to the joint gap“ – mainly to compare adhesives or surface pretreatment methods  smallest differences in the adhesive and cohesive behaviour can be shown – advantage: easy to apply Source: Habenicht 19 Destructive Testing static short-term stress  Peel Stress: ● Four methods for testing: Example of a peeling diagram 1. Angle Peel Test: – result of the test: peel diagram – high force at the beginning joint elements have to be deformed first (absolute peeling resistance)  30 – 90% of the length of the diagram is necessary to show the inhomogeneity of a bond – elastic adhesive layers Kraft F – continuous peeling (relative peeling resistance) Middle separating force Fm  higher peel resistance than brittle layers Length of diagram 20
- Xem thêm -

Tài liệu liên quan