Catalogue - KALLER - (Version JPG) - Page n° 15 - PDF Catalogue | Technical Documentation

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Punching unit, Cam, Spring, Gas spring

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2.1/8

KALLER

About gas springs

For a closed system, as the gas spring, where ¹ the temperature is kept constant (isothermic process) this formula can be simplified to:

Formula ©

p • V = constant (Boyles law)

Example II

What is the spring force of a TU 1500-100 when compressing the spring 80 mm?

F = F •

s init, actual

S - S

nom used •

init, nom

end, nom

^Sused = ⁸⁰ ^mm

The table for the TU 1500 (see page 2.6/12) will give the following values:

Calculating the gas pressure at a certain point of the stroke (S) can be performed in the following way:

Formula ©

^Finit, actual = ¹⁵ ⁰⁰⁰ ^N^Snom = ¹⁰⁰ ^mm

F_init _nom = 15 000 N

init, nom end, nom



^po	(bar)	=	ini tial pressure
^Vo	(l)	=	initial volume
^ps	(bar)	=	pressure at stroke S
^Vs	(l)	=	volume at stroke S

100

F =15 000

15 000 23 000

100 - 80

By combining this Formula © with

Formula O the following Formula © can be derived to

calculate the force at any position of the stroke.

F_s (80mm) = 20 800 N

If the temperature of the gas spring is kept constant, (isothermic process), the spring will give a force of 20 800 N when compressed 80 mm.

Polytropic force increase

For most applications the temperature inside the gas spring will not stay constant during the stroke. For these applications the following formula should be used to calculate the "true" force increase (polytropic process).

Formula ©

1_- ^Finit,nom

S_„ - S

F = F

init, actual

used "

end, nom

Fs (N)

= force at the used stroke S = initial force at current charging

pressure = used stroke

= nominal stroke for the spring = nominal initial force of the spring = force at full nominal stroke

(N)

init,actual

used ^{(mm) S}nom ^(mm)

(N)

init,nom

Formula 0

^Fs ⁼ ^Finit, actual

F.nd (N)

end

S , F. ., and F . are given for each model in

nom imt,nom end,nom ^

the catalogue. If the force has not been changed (the

charge pressure has not been modified)

F ., , . will be the same as the F ., which is the

init, actual init, nom

value given in the catalogue.

Note! All end forces, stated in the catalogue are the isothermic end forces.

used •

init, nom

end, nom

Where n is called the polytropic exponent.

Depending on how fast the gas spring is compressed and the initial gas pressure, the n-value will be between 1 and 1.55. For a normal application in a press tool and a carging pressure of 150 bar, a value of 1.4 can be used.

2^ /Q ^^^T I I We reserve the right to add, delete or modify

■ 1/^ ■^^^^■^■^■^^ components without notification.

Edition 7 / January 2008 ^^CirnShOlrnGn AB All dimensions are stated in mm.

+46 140 571 00 • WWW.kallGr.com All dimensions are nominal unless tolerance is stated.

Catalogue - KALLER - #15

Punching unit, Cam, Spring, Gas spring