Methods of Assembly Flashcards
The method of assembling parts is determined by: (3)
- interference,
- equipment available,
- size of parts being assembled
when one part is pressed onto another, this is called:
Forced fitting
when the hub is heated/expanded to be assembled upon the shaft, this is called:
shrink fitting
when the shaft is cooled/shrunk to allow parts to be assembled upon it, this is called:
expansion fitting
This is the most accurate method of assembly of parts with an interference fit:
forced fitting
When performing a forced fitting, what two types of presses could you use? (2)
- Hydraulic press
- Arbor press
What two styles of hydraulic press are there? (2)
- Free standing hydraulic press
- Portable hydraulic press
As with all fits, the contacting surfaces must be free from:
Grit
it is most important that the axis of the internal and external parts stay in line with each other during a forced fitting. If either part is canted, one or both parts:
May be damaged
tests have shown that smooth mating surfaces free from lubricant give the best grip, however:
anti seize applied before assembly helps reduce seizure and abrasion
to shrink fit parts, the outer part is heated, causing it to expand. What could you use as a heat source? (6)
- Hot water, oil baths
- steam
- oxy/gas hand torches
- oil/gas/electric furnaces
- electronic resistance heating
- electronic induction heating
Allowances for a shrink fit are usually determined by consulting:
the working drawing or suitable tables
The required temperature change depends upon the total expansion required and on the:
coefficient of linear expansion of the metal
instead of heating a hub, the shaft may be:
contracted by cooling
when expansion fitting (freeze fitting), what methods can be used to cool the shaft? (4)
- Industrial refrigerator
- liquid air
- alcohol and dry ice
- liquid nitrogen
This method of cooling gives easy control of temperature and can reach temperatures of around -50C (-58F)
Industrial refrigerator
This method of cooling is able to reach temperatures as low as -120C (-184F)
Liquid air
This method of cooling is similar to liquid air, but a lot safer due to the absence of oxygen
Liquid Nitrogen
This method of cooling is done without expensive equipment. It can produce temperatures of -50C to -60C (-58F to -76F).
Alcohol and dry ice
Note: This method causes frost formation on parts, which could be a problem
Hydraulic presses are classified by: (3)
- Type
- Force output
- function
Hydraulic presses are rated according to their:
Pushing capacity in tons
Mechanical arbor presses are used for ____ jobs
light
an advantage of an arbor press is that it gives the user:
a sense of the amount of pressure being applied
A free standing hydraulic press consists of a frame of substantial construction with devices for holding work pieces, a ram for pushing, and is actuated by:
a pump
a _____ should be attached to all powered presses.
safety cage
by controlling the hydraulic fluid flow with a directional control valve, the cylinder may be:
extended, retracted, stopped
a press that’s fitted with a ram instead of a cylinder is has:
springs that retract the ram when the control valve is released
Powered presses are fitted with adjustable directional control valves to set max working pressure. This valve also operates as a:
Safety release when pressure becomes too high
the workpiece and work holding devices are supported by a slide rack called a:
platen
Note: The platen is supported by safety pins which must withstand the max pressure from the cylinder
to adjust the position of the platen, some presses are fitted with lift cables. When pressing, always ensure:
tension is relieved from the cables.
This type of press consists of a hand pump with a reservoir connected by a high pressure hydraulic hose to a detachable cylinder:
portable hydraulic press aka porta-power
pullers are available in various styles, shape and size. Manual pullers are used for light jobs. For heavier jobs, pullers can be used with a:
portable hydraulic press
what are the three basic situations where a particular style of puller is used: (3)
- Pulling a component off a shaft
- Pulling a component out of a hole
- Pulling a shaft out of a component
the most basic styles of pullers are the: (2)
- two leg and three leg jaw pullers
- rod puller
Note: any style can be used manually or with a portable hydraulic press
the legs of a two or three leg puller can also be called:
grip arms
With a two or three leg jaw puller, what can you replace the adjustable screw with? (besides a portable hydraulic press)
slide hammer
With rod pullers, this is often used to grip or support the work being pulled:
bearing splitter attachment
a bearing splitter is used to:
removing anti friction bearings and other components
shaft protectors are designed to:
protect the shaft center hole and end of puller screw from distortion
What is used to bridge a hole when removing bearings, gears, or other hollow parts on hollow shaft or housing?
step plate adapters
determine the puller type to use by identifying: (4)
- How the part can be gripped,
- Reach
- Spread
- Force required
Regarding pullers, this is based on the length of the part or the distance the part may need to be pulled:
reach
regarding pullers, this is the opening needed to grip the part(usually the width of the part):
spread
Regarding strength and force, the rule of thumb for selecting a manual puller is the adjusting screw should be at least:
half as large as the shaft
Regarding strength and force, and hydraulic applications, the rule of thumb for selecting a puller is: select a puller that will withstand a force exerted in tons-
7-10 times the diameter of the shaft in inches
when using pullers, ____ cannot be stressed enough
safety
