Application #1 – PACKAGING
LINE
An appliance manufacturer
needs to move product in boxes so that they can be presented to
a transfer conveyor after final assembly.
SPECIFICATIONS:
- The boxes weigh 200 pounds
- The unit reciprocates 8 times per minute
- 4.5 inch stroke
- 365 days per year, ten year design life.
- Slightly corrosive environment
ANALYSIS
What is the proper size EXCEL™ Bearing which will satisfy this application?
Configuration: There is
enough space available for four linear bearings. The system will
use stainless steel shafting with a hardness of Rc 55. The load
can be centered between four standard Excel™ linear bearings
Travel Life:
4.5 in./stroke x 8 strokes/min. x 60 min./hr x 24 hrs/day
x 365 days/year x 10 years = 189,000,000 inches.
Load-Life Ratio Factor (RL):
Based on the computed travel life and the load-life curve RL = .22.
Shaft Hardness Ratio Factor (Rh):
For PowerTrax™ HG Stainless shafting with a hardness of Rc 55, Rh
= .70.
Applied Load (La): Per bearing,
La = 200/4 = 50 lbs.
Equivalent Load (Le): Substituting
in the load formula and solving for Le = 50 / (.22 x .70) = 325
pounds
SELECTION
From the EXCEL™ Bearing load tables, the smallest bearing which
exceeds this load rating is the 3/4 inch bearing. However, if the
application is such that the bearing could be oriented for maximum
capacity, then the 5/8 inch bearing could be used.
The Part
List Includes:
4 - XLEC12 EXCEL™ Linear bearings
2 - PowerTrax™ HG Stainless shafting, 9.25 inch minimum length
2 - PowerTrax™ NSB-12 End supports
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Application #2
– SCANNER POSITIONING
A vision system scanner is mounted to the
center of the carriage of a vertically mounted slide system. The
customer wants to use one inch open pillow blocks to guarantee a
long life.
SPECIFICATIONS:
- Scanner weight is 100 pounds
- The center of gravity is offset 4 inches from the carriage plate
- The adjustment distance is 36 inches
- Minimal deflection desired
- Hand adjustment with future automation planned
- A travel life of 10 million inches is desired
ANALYSIS
Configuration: A standard
system with carriage plate and fully supported shafts will assure
minimal deflection.
Load per Bearing:
The load is centered and offset four inches. Use the equations
from the load condition figure “Vertically Mounted” to determine
the worst case force through a bearing. The distance from the load
to the centerline of the shaft (d2) is 4 + 1.187 or 5.187 inches.
The bearing spacing (d0) is set by the carriage plate; d0 = 7 inches.
Based on a design factor of 2, the load per bearing is 74 pounds.
This is far below the rated value of a one inch open bearing.
NOTE: When using open-style bearings, if the
direction of loading force is through the opening of the bearing,
it is necessary to de-rate the bearing capacity by 50%. SELECTION:
The Parts List Is:
SELECTION
PowerTrax™ Series 133 consisting of a double shaft fully supported
system with Carriage 1 and four (4) single bearing blocks.
The Part
List Includes:
133-16-L36
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