4. Threads and Gear Metrology
4. Threads and Gear Metrology
Objective :
4.1. Screw Thread Measurements :
Important Points Discussed :
1. Screw Threads are used mostly in all Components/Machine Assemblies. They perform function of power transmission as well as fastening. So, it is essential to know various terminologies related to Screw Threads.
2. Terminology used in Screw Thread measuremet
a. Pitch
b. Lead
c. Flank Angle
d. Thread Angle
e. Helix Angle
f. Major diameter
g. Minor diameter
h. Effective Diameter
3. Ways to measure various Diameters :
We studied about the Floating Carriage dial micrometer, its working principle, and the procedure for measuring Major, Minor, and Effective diameter.
It can be utilized in two ways - Using Two wire and Three wire method.
4. Ways to measure Screw Pitch :
The Pitch of the screw can be measured in three ways :
a. Using Profile Projector
b. Pitch Guage - Consists of Blades Containing v-grooves, and pitch engraved on it.
c. Peter Screw measuring machine ;
Screw is held between Micrometer and centre, and Stylus is moved over the screw.
5. Various errors occuring in Screw Threads and ways to encounter it. Some of the common errors are :
a. Drunken Thread
b. Progressive Pitch Error
c. Periodic pitch error
d. Irregular error
4.2 Gear Measurement and Testing :
Important points discussed :
6. Gears are most commonly used in trasnmission of power and motion. They have numerious applications in automobiles, machine equipments, electronic system, etc.
7. In order to maintain constant motion and power transmission, Gear geometry must be according to the manufacturers specifications. For this purpose, Gear testing and measurement processes are essential.
8. Various types of gear terminilogies were studied. Such as - Base circle, Pitch circle, Module, Circular pitch, Tooth thickness, Helix angle, Dedendum, Addendum, Pitch diameter, and Number of teeth.
8. Testing methods are classified into two types - Analytical (Physical Parameters) and Functional (Checking of gear running with another gear).
9. Gear Tooth Vernier is a device used to measure analytical characteristics of the gear. It is similar to the Conventional vernier caliper, except it has two moving jaws and two Fixed Jaws. One of the quantity must be known to uce the Gear ToothVernier.
10. We have conducted practicle earlier on Profie Projector, it is also used for measurement of analytical parameters of gear. With the use of this instrument, Measurement purpose has became easier.
11. Parkinson Gear Tester is the most important instrument used for the checking of functional parameters of the gear. A master gear is used along with manufactured gear, to chech its functioning.
12. The pitch measuring machine uses dial indicator to show the variation in pitches of the gear, if they are in determined range, gear if proceed for usage.
13. In the involute measuring machine, we studied the working principle, stating that if a straight edge is rolled around a base circle without slipping, the stylus of the dial guage attached to it, gives Involute.
14. For the optimum functioning, the errors such as Pitch error, Tooth thickness error, Radial run out, and Backlash needs to be eliminated.
Objective :
- To understamd and use various methods of calculating Thread elements and elements of Gear.
4.1. Screw Thread Measurements :
Important Points Discussed :
1. Screw Threads are used mostly in all Components/Machine Assemblies. They perform function of power transmission as well as fastening. So, it is essential to know various terminologies related to Screw Threads.
2. Terminology used in Screw Thread measuremet
a. Pitch
b. Lead
c. Flank Angle
d. Thread Angle
e. Helix Angle
f. Major diameter
g. Minor diameter
h. Effective Diameter
3. Ways to measure various Diameters :
We studied about the Floating Carriage dial micrometer, its working principle, and the procedure for measuring Major, Minor, and Effective diameter.
It can be utilized in two ways - Using Two wire and Three wire method.
4. Ways to measure Screw Pitch :
The Pitch of the screw can be measured in three ways :
a. Using Profile Projector
b. Pitch Guage - Consists of Blades Containing v-grooves, and pitch engraved on it.
c. Peter Screw measuring machine ;
Screw is held between Micrometer and centre, and Stylus is moved over the screw.
5. Various errors occuring in Screw Threads and ways to encounter it. Some of the common errors are :
a. Drunken Thread
b. Progressive Pitch Error
c. Periodic pitch error
d. Irregular error
4.2 Gear Measurement and Testing :
Important points discussed :
6. Gears are most commonly used in trasnmission of power and motion. They have numerious applications in automobiles, machine equipments, electronic system, etc.
7. In order to maintain constant motion and power transmission, Gear geometry must be according to the manufacturers specifications. For this purpose, Gear testing and measurement processes are essential.
8. Various types of gear terminilogies were studied. Such as - Base circle, Pitch circle, Module, Circular pitch, Tooth thickness, Helix angle, Dedendum, Addendum, Pitch diameter, and Number of teeth.
8. Testing methods are classified into two types - Analytical (Physical Parameters) and Functional (Checking of gear running with another gear).
9. Gear Tooth Vernier is a device used to measure analytical characteristics of the gear. It is similar to the Conventional vernier caliper, except it has two moving jaws and two Fixed Jaws. One of the quantity must be known to uce the Gear ToothVernier.
10. We have conducted practicle earlier on Profie Projector, it is also used for measurement of analytical parameters of gear. With the use of this instrument, Measurement purpose has became easier.
11. Parkinson Gear Tester is the most important instrument used for the checking of functional parameters of the gear. A master gear is used along with manufactured gear, to chech its functioning.
12. The pitch measuring machine uses dial indicator to show the variation in pitches of the gear, if they are in determined range, gear if proceed for usage.
13. In the involute measuring machine, we studied the working principle, stating that if a straight edge is rolled around a base circle without slipping, the stylus of the dial guage attached to it, gives Involute.
14. For the optimum functioning, the errors such as Pitch error, Tooth thickness error, Radial run out, and Backlash needs to be eliminated.
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