41 Questions
What are the advantages of welded joints in metalworking?
Big strength, indispensable for special manufacturing, maintenance for cracked & weared elements, productive, can be easily automated with robots, advantageous shapes can be designed from deflection & strength point of view
What are the disadvantages of welded joints in metalworking?
Only for certain materials, warpage due to high local heat concentration, after-welding process needed, no damping effect, non-destructive control of the joint is cost effective
Define welding joint in metalworking.
A welding joint in metalworking is a point or edge where two or more pieces of metal or plastic are joined together with the same materials, formed by welding according to a particular geometry.
What is the purpose of non-destructive control of welded joints?
The purpose of non-destructive control of welded joints is to ensure cost effectiveness in assessing the joint's quality.
What are the main types of welding techniques mentioned in the text?
MMA, MIG, TIG, FCAW, SAW, SMAW, Resistance welding, Forge welding, Friction welding, Induction welding
What are the main types of welded joints discussed in the text?
Butt joint, lap joint, strap joint, corner joint
What is the difference between weld metal (bead) and heat affected zone (HAZ) in welded joints?
Weld metal is molten and solidified during welding, contains filler material, and may have different chemical composition, while HAZ is not melted but heated and cooled, contains significant filler material, and has similar chemical composition to parent metals.
What are the design principles for welded assemblies mentioned in the text?
Use materials with high weldability, minimize the number of welds, avoid shaping parts based on casting or forging, use standard components, select the proper location and sequence of welding
What are the good practices to be followed for creating welded joints?
Avoid joints near peak stress points, avoid joint lines crossing, place joints far from cold-bent sections
What are the incorrect practices to be avoided for creating welded joints?
Placing joints at peak stress points, crossing joint lines, welding near cold-bent sections without sufficient clearance
What are the characteristics of a butt joint?
It is strong, reliable, and cheap, but requires rework at metal sheets.
What are the characteristics of a lap joint?
It has poor quality, double weld metal, more material, and additional bending.
What are the characteristics of a strap joint?
It resembles a riveted joint, has big load capacity, quadrant weld metal, more material, and no additional bending.
What are the characteristics of corner joints?
There are several types with varying load capacity and complexity, but may require additional rework.
What is the main feature of weld metal in a welded joint?
It undergoes phase change during welding.
What is the primary feature of the heat affected zone (HAZ) in a welded joint?
It remains solid and its width can be controlled.
What are the engineering guidelines for designing glued joints?
Ensure homogenous load distribution, avoid impact and peeling effects, increase glueing surface, and avoid additional load cases.
How does the load carrying capacity of lap joints compare between one-way and reverse-way joints?
One-way joints can carry approximately twice the load of reverse-way joints if their Young's moduli are the same.
What is the stress congestion factor used to describe in lap joints?
The stress congestion factor is introduced to describe stress peaks on joint edges, which can lead to failures.
How can the stress congestion factor in lap joints be reduced?
It can be reduced by utilizing one-way lap joints, short joints, soft glueing material with rigid substrates, and varying cross sections.
What is the stress congestion factor (α) in the calculation of lap joints?
The stress congestion factor (α) is the maximum stress divided by the average stress.
How do tapered lap joints improve stress distribution?
They improve stress distribution by tapering the joint sections, using scarf joints, glueing belt ends, and reinforcing with tapered substrate endings.
What are the consequences of incorrect designs of glued joints?
Incorrect designs may lead to unsatisfactory performance or failure.
What is the process of joining two metal objects using a third metal alloy called solder?
It is known as soldered joint formation.
What are the advantages of soldered joints?
Advantages include good electrical conduction, sealing ability, and short assembly time.
What are the disadvantages of soldered joints?
Disadvantages include relatively small load carrying capacity and high surface preparation costs.
In which applications are soldered joints commonly used?
They are common in vessel base, pipe attachment to sheet metal, beam attachment to sheet metal, shaft attachments, and sheet metal to sheet metal applications.
Where are soldering variations commonly used?
Soldering variations are commonly used in machinery, plumbing, and electronics industries to join various materials.
What type of joints should be avoided at corner joints?
Skew connections
What phenomenon in glued joints involves pressure-sensitive adhesives?
Viscoelastic bonding effect
What components can be determined for stress in welded joints?
Normal and transverse planes, including λ⊥, λII, τII, τ⊥, τ⊥√τ⊥² + λII² − λ⊥λII + 3(τ⊥² + λII²), and σö
What should the resultant stress (σö) be in relation to the ultimate stress (σH) for a correct weld?
Below
What is the physical phenomenon of glued joints involving pressure-sensitive adhesives (PSAs)?
Viscoelastic bonding effect
What type of joints should not be placed at corners or bending curves in cold worked sheet metals?
Welded joints
What type of joints should be welded as double at dynamic loads?
Corner joints
What should the rib not have to avoid melting during welding?
An apex point
What should be avoided on the root side at spot welded joints?
Tension forces
What are the advantages of glued joints?
No heat affected zone, no alteration in material, small amount of space and weight required, sealing and corrosion resistance, damping effect, no pre-drilling of metal sheets
What are the disadvantages of glued joints?
Long preparation time, need for preparation of surfaces, potential requirements for pressing machines and cleaning machines, sensitivity to high temperatures, aging, sensitivity to ultra violent and oxidation of the air, potential release of harmful gases during processing and recycling
How can contact glues be applied?
By smearing both surfaces and then pressing them together
What influences the strength of glued joints?
Glue material, kind of substrates, operation conditions, geometry of the glueing gap, load case
Study Notes
- At cold worked sheet metals, welded joints should not be placed at corners or bending curves due to aging or rigid fracture.
- Corner joints should be welded as double, with a concave design at dynamic loads.
- The rib must not have an apex point, as it melts during welding.
- Skew connections should be avoided at corner joints.
- Tension forces should be avoided on the root side at spot welded joints.
- Weld nomenclature includes terms such as "Anyaggal záró kötések," "Gépelemek," and "elsőadás."
- Static loads can be calculated using the dimensions of the welded joint, as well as the stresses in the weld (tension, bending, shearing, and torsion).
- Stress components in the normal and transverse planes can be determined, including λ⊥, λII, τII, τ⊥, τ⊥√τ⊥² + λII² − λ⊥λII + 3(τ⊥² + λII²), and σö.
- The weld is considered correct if the resultant stress (σö) is below the ultimate stress (σH), which depends on the yield stress of the weaker material, the gain factor of the weld, and the safety factor of the weld.
- Glued joints involve the process of joining two surfaces together, usually with the use of glue, epoxy, or plastic agents.
- Advantages of glued joints include no heat affected zone, no alteration in material, small amount of space and weight required, sealing and corrosion resistance, damping effect, and no pre-drilling of metal sheets.
- Disadvantages of glued joints include a long preparation time, the need for preparation of surfaces, potential requirements for pressing machines and cleaning machines, sensitivity to high temperatures, aging, and sensitivity to ultra violent and oxidation of the air, and the potential release of harmful gases during processing and recycling.
- Physical phenomenon of glued joints involves pressure-sensitive adhesives (PSAs), which are viscoelastic and have a physical (viscoelastic) bonding effect.
- Chemical phenomenon of glued joints involves the interaction of surface molecules, leading to attractive forces and either physical (adsorption), chemical (covalent bonding), or electrostatic (van der Waals forces) bonding effects.
- Contact glues can be applied by smearing both surfaces and then pressing them together, while melt glues are applied in the melted phase and then matched together before solidifying. Plasticoles are applied as an adhesive pasta and harden on heating.
- The strength of glued joints is influenced by the glue material, kind of substrates, operation conditions, geometry of the glueing gap, and load case.
This quiz discusses the construction of welded joints in cold worked sheet metals, emphasizing the avoidance of welded joints at corners or bending curves due to aging or rigid fracture. It also covers the proper construction of corner joints and considerations for dynamic loads.
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