# Formula required from set of data

1. Feb 7, 2013

### Mytheral

Hi Guys,
Im doing my work placement at a steel processing facility and have been asked to derive a formula for quoting purposes that relates to radial bending on a press brake machine,

The formula is needed to show the radial pressing increments on steel and the data they have given me is as follows

At 150mm radius the distance between presses is 10mm
at 200mm radius it is 20mm
at 400mm radius it is 25mm
at 600mm radius it is 30mm
at 900mm radius it is 40mm
at 1500mm radius it is 50mm
at 2000mm radius it is 70mm

the formula does not need to be exact, it just needs to be a guideline for an entry level quoter.

any help would be greatly appriciated.

Katie

2. Feb 7, 2013

### ZapperZ

Staff Emeritus
Plot it and look at what the graph looks like.

BTW, are you allowed to seek help with this?

Zz.

3. Feb 7, 2013

### Mytheral

Yes my manager advised me to post it on this forum. i have graphed it but am just having a mental block at the moment, must be due to the approaching weekend

i was originaly going to use a graph incorperated into excel for the quoters but my boss wants a formula :(

Katie

4. Feb 7, 2013

### Mytheral

Hi Guys,
Im doing my work placement at a steel processing facility and have been asked to derive a formula for quoting purposes that relates to radial bending on a press brake machine,

The formula is needed to show the radial pressing increments on steel and the data they have given me is as follows

At 150mm radius the distance between presses is 10mm
at 200mm radius it is 20mm
at 400mm radius it is 25mm
at 600mm radius it is 30mm
at 900mm radius it is 40mm
at 1500mm radius it is 50mm
at 2000mm radius it is 70mm

the formula does not need to be exact, it just needs to be a guideline for an entry level quoter.

any help would be greatly appriciated.

Katie

5. Feb 7, 2013

### Staff: Mentor

Excel's "trendline" option allows you to fit various kinds of curves to the data (linear, polynomial, exponential) and display the equation. Play around with the different kinds of curves and see which one gives the best-looking result.

6. Feb 7, 2013

### Mytheral

i can plot the info in excel but cannot find how to derive a formula. any help is greatly appriciated

7. Feb 7, 2013

### nvn

y = (1.57e-8)(x^3) - (5.094e-5)(x^2) + (0.0724)(x) + 3.35, for 150 ≤ x ≤ 2000 mm, where x = bend radius (mm), and y = distance between presses (mm).

Last edited: Feb 8, 2013
8. Feb 7, 2013

### Mytheral

thankyou so much, your help is greatly appriciated

9. Feb 8, 2013

### nvn

Mytheral: Here is another approach, a linear approximation, in case you prefer it more than the cubic polynomial function in post 7.

y = 0.0285*x + 11.6, where x = bend radius (mm), and y = distance between presses (mm).