Determine Belt Length
The first thing needed for any spiral is to find how long the belt has to be. Use the questions below to help gather the information you will need.
What is Needed:
|
Why:
|
Product to be conveyed
|
This helps with belt selection
|
Length of product as it will travel in the spiral
|
Needed for formula, changing product orientation affects belt length needed
|
Pieces of product per minute
|
Needed for formula, contact us if this cant be easily determined
|
Dwell time in spiral
|
Needed for formula, contact us if this is an unknown factor
|
Pieces across Belt
|
Needed for formula
|
Ok now it is time to use the information you have just collected above. Put the information into the formula below.
Belt Length Formula:
Example:
This example will be used throughout the Spiral Help steps.
Product:
|
Pizza Crust
|
Size:
|
12" diameter
|
Rate:
|
100 pieces per minute
|
Dwell Time:
|
30 Minutes (cooler)
|
Pieces Across Belt:
|
Want 3 (makeup line feeding this cooler is 39", want to use 36" wide belt to save floor space, will put 3 across on slight diagonal to accomplish smaller belt width).
|
|
|
12x30x100x1.45
36
|
= 1450 ft of active belt length needed
|
Notes on This Example:
Determine Belt Width
Belt width selection is made by determining how the products will be loaded onto the spiral, what type of belt is being used and whether the spiral is an upgo or downgo. For downgo spirals add 2" to the belt width for hold down rail.
Spiral Loading:
Belt Types:
Rod type belts:
(Belt edges are typically not used for product loading)
|
|
Flex type grid belts:
(Belt edges are usable for product loading)
|
|
Flex type plastic belts:
(Belt edges are usable for product loading)
|
|
Hold Down Rails:
Hold down rails are commonly used on descending spirals and require and additional 2 inches of belt width.
Belt Width Details
This section gives you information on all widths and belt lengths per tier, outside frame dimensions, and will assist in the overall size of the spiral unit.
Belt Width Charts
Notes on Example:
In this example, a 38" wide belt could easily be used if you chose a flex or plastic belt. A rod type belt would be more difficult, assuming a horizontal loading pattern. A 40" wide rod type belt could be a good choice. This example assumes and ascending spiral.
Determining how many tiers are needed
Tiers are determined by taking active feet needed and dividing by feet per tier. Feet per tier can be seen on the attached charts showing all belt widths for a given radius. In this example, if we use a 38" wide belt with a standard 2.2 radius type belt, we see there is 63.88 ft per tier.
1450 ft needed = 22.7 tiers needed
63.88 ft per tier
Determine belt radius to be used
2:2 to 1 radius Most standard used
1:7 to 1 radius
1:5 to 1 radius
1:1 to 1 radius
Other (contact us)
If this is a straight through spiral, round out to 23 tiers
If this is a 90-degree discharge spiral, round to 22.25 tiers
If this is a 180-degree discharge spiral, round to 22.50 tiers
The exact final number of tiers can be determined when the final layout of the spiral is made, but typically the layouts change to accommodate the line layout, so this will suffice to go out and get quotes.
Determine Tier Pitch
Need highest/thickness product to be run in the spiral
This number, is manufacturer specific, but the following guidelines will be accurate enough to determine what is needed for layouts and quotes:
Highest Product to be run + 3.75" = tier pitch
3.75" allows for air movement above the product plus belt support structure and belt thickness. For critical sizing and space considerations, contact us for specific manufacturers support design dimensions.
Taking our 12" pizza crust example, use 1" thickness for the product
Based on this, we have a tier pitch requirement of at least 4.75". From a practical side of design, a more typical tier pitch would be 5.5" or 6", especially if you are using wider belts, which require a persons arm to extend into the spiral for maintenance or clearing out products.
Determine Discharge Heights/Overall Heights
|
|
|
|
|
|
|
(23 tiers X 6" tier pitch)138"
|
|
|
|
|
|
|
|
|
|
|
178" product discharge height
|
|
|
|
|
|
Top structure height (use 10")
|
|
|
|
|
|
188" Top of Spiral Height
|
|
|
Preliminary Information for you to use in Looking for a spiral:
For this application, we need a spiral that has: 1450 ft of active belt
38" wide belt suitable for conveying this product (pizza crust)
23 tiers
6" tier pitch
infeed at 36"
Product discharge at 178"
Top of Spiral frame at 188"
Outside diameter of spiral is 21'8"
With this information in hand, you can now go out and look for a spiral system knowing what you need. The next step is to get a price for this unit. Contact us for this, the closer you look the better we look
Back to Engineering
|