Tài liệu Ktf_8_hybridfügen final

Adhesive Manufacturing Processes Chapter 8: Hybrid Joining Univ.-Prof. Dr.-Ing. Prof. h.c. Stefan Böhm Department for Cutting and Joining Manufacturing Processes (tff) University of Kassel, Germany Source: Wikipedia Agenda  Introduction  Relevant Joining Methods  Possible Combinations  Fields of Application and Examples 2 Hybrid Joining in General  Hybrid joining is a combination of two or more elemental joining methods  The joining processes ● are in the same areas of the workpiece ● parallel or after each other  Goal: ● compensate negative charateristics of the bonding methods ● combine positive characteristics of the bonding methods with each other Source: DVS – Ausschuss für Technik 3 Properties of Adhesively Joined Bonds  Negative Properties of Bonds ● low beginning strength ● low peel strength ● tendency to creep ● dependent on time, temperature and environment  Positive Properties of Bonds ● transmission of force onto a bigger surface ● high potential for leight weight constructions ● increased stiffness of construction elements Source: Uni Siegen 4 Reasons for Hybrid Joining  Interpretation: ● application of easy bonding methods achieves the best bond forces load adhesive bonding (brittle-hard epoxy resin) hybrid joint ● lower bonding forces of hybrid bonds through damage of the adhesive layer during mechanial joining processes riveted bond ● but: purely adhesively joined bonds last less longer path  Goal: increase of durability and therefore a better usage of the material characteristics Pic. 1: Relative bonding strength: adhesive bonding – hybrid bonding – riveted bonds Source: EAA, Matter at University of Liverpool 5 Why is a spot-joined structure also joined adhesively?  Increase of energy absorption under impact stress  More equal distribution of tension  Increase in vibration strength  Improvement of vibration damping  Increase of connection stiffness  Sealing of the bonding seem against gases and fluids  Improvement of corrosion resistance Source: Uni Siegen 6 Why is an adhesively bonded structure also spot joined?  Fixation of joint elements until the adhesive is cured  Relief of peel stress  Partly compensation of loss in hardness due to ageing  Increase of procedural temperature range  Reliefl of adhesive bond when under high static load Stress: Uni Siegen 7 Agenda  Introduction  Relevant Joining Methods  Possible Combinations  Fields of Application and Examples 8 Classification of Joining Methods According to DIN 8593 Group 4.1 Composition Group 4.2 Filling Group 4.3 Pressing in and on Group 4.4 Joining through casting Main Group 4 Joining DIN 8593 Teil 0 Group 4.5 Joining through forming Group 4.6 Joining through Welding Group 4.7 Joining through Soldering Group 4.8 Adhesive Bonding Group 4.9 Textile Joining 9 Hybrid Joining Methods that Are Relevant for Adhesive Bonding  Industrial applications of these hybrid joining methods (selected): ● Spot Welding – Bonding ● Riveting/Studding – Bonding ● Punch Riveting – Bonding ● Clinching – Bonding ● Folding – Bonding Pic. 2: Hybrid-joint of CFK-aluminiumprofile with adhesive through setting bolts Source: Habenicht, S.608 10 Classification of Relevant Joining Methods According to DIN 8593 Gruppe 4.3. Pressing in and on Screwing Punch Riveting Riveting Gruppe 4.5. Reforming Main Group 4 Joining DIN 8593 Teil 0 Clinching Folding 4.6. Welding resistance spot welding 4.8. Adhesive bonding 11 Strengths and Weaknesses of the Joining Method - Overview (1) good moderate Material variety Hardness on sm. area Flat force Initiation Damage of the joint element bad Adhesive Bonding Spot Welsing Riveting Punch Riveting Screwing Clinching Folding Table 1: Analysis of the strengths and weaknesses (1) 12 Strengths and Weaknesses of the Joining Method Overview (2) good moderate Temperature Resistance Distortion Density Damping Inconspicuou sness/Design bad Adhesive Bondig Spot Welding Riveting Punch Riveting Screwing Clinching Folding Table2: Analysis of the strengths and weaknesses (2) 13 Strengths and Weaknesses of the Joining Method Overview (3) good moderate bad Fixation Procedural length Forecast of duration Removability Adhesive Bonding Spot Welding Riveting Punch Riveting Screwing Clinching Folding Table 3: Analysis of the strengths and weaknesses (3) 14 Agenda  Introduction  Relevant Joining Methods  Possible Combinations  Fields of Application and Examples 15 Hybrid Joining Methods: Resistance Spot Welding - Bonding 16 Procedural Description - (Resistance) Spot Welding (1)  Classification according to DIN 8593: Group 4.6 Welding  Welding Procedure of sheets and profiles  Definition „By applying two electrodes, the elements that are to be welded are integrated into an electrical circuit. The bonding area heats up, due to electrical resistance and a welding spot is formed.“ Source: Waldmann 17 Procedural Description - (Resistance-)Spot Welding (2)  Functional Principle: ● welding charge is started ● narrowed cross-section provides Force Electrode Energy: alternating current impuls resistance ● additional resistance through work pieces  Consequence: ● electrode heats up work piece workpiece ● material is partly melted Electrode Pic. 3: Functional principle of resistance spot welding Source: Zinn 18 Procedural Description - (Resistance) Spot Welding (3)  Implementation: (A) Positioning of workpiece (A) (B) (C) (D) (B) Pressing of electrodes on workpiece (C) Current flows between the electrodes; material is partly melted (D) The materials are welded Pic. 4: Spot Welding – Procedure Source: Rime 19 Hybrid Joining Methods: Spot Welding – Bonding (1)  Method of Fixation: ● Adhesive is applied to the joint elements ● A welding spot is set ● Curing of adhesive layer 1st Step: Preparation of joint element 2nd Step: Application of adhesive 3rd Step: Positioning of joint elements Abb. 5: Fixiermethode 4th Step: Joining 5th Step: Completed Source: EAA, Matter at University of Liverpool 20