Roll Machine
Roll-operation: from the rotating roller, squeeze imposed on the material, friction,
So that the materials through the roll gap formed in the role of certain shapes and sizes of operation.

Roll forming machine
Section roll theory
An ideal roll process
Ideal roll conditions:
1, each pair of roller diameter equal to the same speed, and the same time.
2, was pressed material constant velocity.
3, the material force only pressure roller.
4, row materials, mechanical properties of uniform
5, the volume of material to be pressure before and after the change.
Second, rolling parameters
1, the material roll before and after deformation

Absolute reduction rate: △ h = h0 - h1
2, contact angle
Can be obtained according to plan

In general α is small
3, deformation coefficient
(1) reduction factor δ
δ = h1/h0
∵ h0> h1 ∴ δ <1 δ deformation
(2) extension coefficient λ
λ = L1/L0
∵ L 01 λ to extend the amount of
(3) wide exhibition coefficient β
β = b1/b0
∵ b 0 ≈ b1 ∴ β ≈ 1
(4) δ, λ, β the relationship between
Roll from the ideal conditions for V0 = V1
Are: h 0 b 0 L 0 = h 1b 1L 1
Or:
∴ δλβ = 1
∵ β ≈ 1
∴ δ λ ≈ 1
If the number is set roll n, then roll on the changes in the thickness
h1 = δ1 h0
h2 = δ2h1 = δ1δ2h0
... ...
hn = δnh n-1 = δ1δ2 ... ... δ n h0
Bringing the total reduction factor of δ
Is: δ = hn / h0 = δ1δ2 ... ... δ n
Similarly get: λ = λ1λ2 ... ..Roll forming . λ n
Third, the process of movement calculated roll
Under ideal conditions roll: roll the volume of materials before and after the change (V0 = V1)
Are: Q0 = Q1 (roll flow before and after change)
∴ h 0 b0 u0 = h 1b1 u1
Type in: u0 - material in the roller speed at the entrance
u1_-material in the exit speed of roller
∵ b0 ≈ b1
h 0 u0 = h 1 u1

Or u1 = λ1 u0

The second roll exit velocity: u2 = λ2 u1 = λ1λ2 u0
Set by the n-roll: un = λ1λ2 ... ... λnu0 = λ total u0
∴ λ total> 1 u n> u0
Fourth, import conditions and determine the diameter of roller
(1) import conditions
A point of contact with local materials, loading situation shown in Figure

Roll gap materials can be successfully imported, must meet
T x ≥ P x
Fsinφcosα ≥ Fsinαcosφ
∴ tg φ ≥ tgα
Or f ≥ tgα
φ ≥ α
f-materials and the friction coefficient of the surface roller
2, roller diameter to determine
The import conditions: tg φ ≥ tgα
The equation can be of a certain time when φ, △ h D structure size
Thinking Question: Why continuous roller press in the first general of the larger diameter roller, and has opened a trench
5, horizontal pressure
1, the concept of horizontal pressure
Material through the roller gap, the material will be produced by roller to the force and tangential force. Radial force called the horizontal pressure; shear force called the contact stress.
Cross-pressure is always perpendicular to the roll surface, the result of its role is to separate the two rollers. Transverse size of the pressure changes with the material thickness changes. Roll gap slightly in the horizontal pressure value before the Office, the largest.
Contact stress of the material pulled into the roll-gap, but the direction depends on the material relative roller speed, as bb interface material and the roller relative velocity is zero, so the section was zero contact stress.
2, the calculation of horizontal pressure
Transverse stress the importance of mechanical design parameters of roll, the size of the impact of the structural parameters of roller press and power consumption, many factors affect the cross-pressures.
Test measured: material hardness greater the lower the temperature, smaller roll gap, the greater the horizontal pressure.
Currently the calculation of accurate cross from the theory, the pressure is difficult, only the help of food materials with similar theoretical calculations.
According to theoretical calculation of horizontal creep stress
Materials for the Newtonian fluid assumption, derived under the principle of fluid mechanics, pressure may cross the formula:

The formula: P-horizontal pressure (kg)
μ-Viscosity (kg.s / cm2) cold roll forming machine
u-roller speed (cm / s)
R-roller radius (cm)
L-roller effective length (cm)
e - roller gap (cm)
h0-material thickness before the roll (cm)
Theoretical calculation has some error, conditional on similar devices can be measured.
6, computing capacity
1, in advance, the concept of lag

Advance District: cdef District
According to principles of fluid mechanics (no lateral spread)
huH = h2u

∴ u> uH type in: ub - roller speed
∵ in the cd section are: ub = uH u-materials after the rate of pressure
∴ u> ub uH-cd speed section of materials
The material after the pressure ahead of the large velocity θ-angle
In line roller speed, said material
Relative pressure roller ahead.
2, ahead of rate ρ
Have patterns that: huH = h2u
∵ uH = ub ∴ u = ρub
Set: h2 = e (roll gap)
∴ h = h2 +2 (R-Rcosθ) = h2 +2 R (1-cosθ) = h2 +4 R
∵ When θ is very small
Calculating the angle advance

Type in: f-friction coefficient
3, computing capacity

The formula: G-capacity (kg / h)
Q-volume flow (m3 / h)
After γ-material pressure density (kg / m3)
After the speed u-material pressure (m / min)
Assignment: Given: biscuit machine production line conveyor belt surface speed u4 = 8m/min, now you want to design a continuous biscuit tablet press, tablet press of the three pairs of rollers driven by an electric motor , pressure roller and the surface with the friction coefficient f = 0.8, D1 = φ210mm, D2 = φ180mm, D3 = φ180mm, h0 = 35mm, h1 = 15mm, h2 = 10mm, h3 = 5mm. test requirements: (1) roller press three sections of canvas conveyor line speed you how many (2) roller press three pairs of roller speed of each line number (3) If the motor speed is 1450rpm, the transmission gear ratio of 30, test the design of the tablet press the transmission system and transmission system plans drawn.
Of which:
α-contact angle (ie, the center of the corresponding material deformation zone angle)
D-diameter roller
e-roller gap
In theory e = h1

F-roller force on the material
T-roller friction of materials
P-pressure roller pressure on the materials being
φ-friction angle
α-Import angle
P x, T x-P, T horizontal component
P y, T y-P, T vertical component
Have been derived:
Lag District: abcd District
u'h1 = huH
Section in the cd
∵ uH = ub
∴ ub> u '