Chapter 6 Chain Drive.pdf

Microsoft PowerPoint Chapter 6 CHAIN DRIVE 20/3/2023 1 20 Mar 23 1 CHATER 5 CHAIN DRIVES THEORY OF MACHINE AND MACHINE DESIGN DEPARTMENT OF EDUCATION AND TRAINNING HOCHIMINH CITY UNIVERSITY OF TECHNOL[.]

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CHATER 5: CHAIN DRIVES

THEORY OF MACHINE AND MACHINE DESIGN

DEPARTMENT OF EDUCATION AND TRAINNING

HOCHIMINH CITY UNIVERSITY OF TECHNOLOGY AND EDUCATION

TS Phan Công Bình binhpc@hcmute.edu.vn binhpc.tpm@gmail.com

Target

1 Understanding the basic of chain drives

2 Understanding dynamic of the chain drives

3 Design the chain drives

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Theoretical contents

I Overview

II Sequence of calculation and design the chain drives

III Exercise 3

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TS Phan Công Bình binhpc@hcmute.edu.vn binhpc.tpm@gmail.com 20-Mar-23

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Overview

1 Structure

1 Driving sprocket 2 Driven sprocket 3 Chain4 Chain tensioner

1

2

3

4 4

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d1, Z1pitch diameter and number of teeth on the sprocket 1

d2, Z2pitch diameter and number of teeth on the driven sprocket 2

a: Centre distance

2 Geometrical parameters

Overview

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Movement and load are transmitted from the driving sprocket to the

driven sprocket based on the principle of matching in chain drive

3 Operating principle.

Overview

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A chain tensioner is applied to increase the performance of the drive

3 Operating principle.

Overview

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Based on structure :

Roller chain

Bush chain

Inverted tooth chain

4 Classification

Overview

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Based on lines of chain:

1 line chain

Multiple lines chain

4 Classification

Overview

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Conveyor chain Chain drive Lifting chain

Based on the load mode:

4 Classification

Overview

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Advantages:

Overview

5 Advantages and disadvantages

synchronized chain drive

Far center distance transmission (<8m)

Less tension adjustment

small force effected on shaft

No sliding

Smaller structure compared to belt drives

Long lifetime

Transmit to multiple shaft at the same time

(synchronized function)

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 Cause noise due to impact

 Unstable instantaneous ratio

 Complex in manufacturing,

assembly and maintenance

Disadvantages :

Overview

5 Advantages and disadvantages

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6 Application

Overview

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7 Broken patterns

Hinge Abrasion increasing pitch Out of chain

Overview

 Broken roller

pc

Theoretical contents

I Overview

II Sequence of calculation and

design the chain drives

III Exercise

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Chain selection: => Roller chain

Number of teeth on sprocket:

Z1  29  2u

Z2  uZ1

(Roller chain11 15 < Z < 100 120)

Sequence of calculation and design the chain drives

P1(kW) Power on the driving sprocket

n1(rpm) Rotation speed of the driving sprocket

u Ratio

1 Initial parameters

2 Determine parameters of chain drives

Z should be odd number

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 Calculationpitch of chain directly by the following equation :

3 3

1 0 x 1 1 0 x

c Z  p  K Z n  p  K

p  2.82

 Based on satisfied standard abrasion and searched in Table 5.4 ([P] andn01)

K KzKn

Kx

Pt P1  P

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n01=50 n01=200 n01=400 …

Based on n1to determine n01(the closest given range)

Based on n01andPt, [P] is selected in Table 5.4

01

n

p



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Pitch of

chain

(mm)

diameter

dc,(mm)

Length of

Bushing

(mm)

Allowable power [P], kW, rotation speed of driving sprocket

n01 ,(rpm)

-Pt=5.5 kW

n1=350 rpm

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Kxis coefficient of uneven load distribution depend on lines of chain :

 Kzcoefficient of the teeth number on the driving sprocket :

 Kn coefficient of the rotating speed of the driving sprocket:

01 1 n

n K

n



01

25 z

Z K

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 Kr– Coefficient of Dynamic load:

+ Smooth performance Kr=1,

+ Impact load Kr=1,2÷1,5;

+ Strong impact load Kr=1,8

K= KrKaK0KdcKbKlv

 Ka– Coefficient of center distance

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K0– Coefficient of the drive position The angle taken by the

center line and the horizontal line is smaller than 60oK0= 1,25

Kdc– Coefficient of ability to adjust chain tension:

+ Kdc= 1 for center distance adjustment

+ Kdc= 1,1 for employing chain tensioner

+ Kdc=1,25 for chain drive can not adjust tension

KbCoefficient of lubrication conditions:

+ Kb= 0,8 for continuously lubricating;

+ Kb= 1; for dripping lubricating

+ Kb= 1,5 for periodic lubricating

Klv– Coefficient of working shift a day

+ Klv= 1 for 1 shift

+ Klv= 1,12 for 2 shifts

+ Klv= 1,45 for 3 shifts

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Pitch circle diameter

Note: d2should be smaller than 600(mm), or it is limited by the specific conditions

Then, lines of chain can be increased to reduce d2

xmust be even number

1

1 sin c p d Z





Chain link

Centre distance

2

2 sin c p d Z





𝑥 = 2𝑎

𝑝𝑐

+ 𝑍1+ 𝑍2

𝑍2− 𝑍1 2𝜋

𝑝𝑐 𝑎

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 Instantaneous velocity:

Instantaneous ratio:

u Z cos

Z12cos



  

Z1 Z1

  

Z2 Z2

cos





3 Validation of chain drive dynamic

a Instantaneous velocity and ratio of chain drive

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b Average velocity and ratio chain

Average velocity:

1

6.104

Z1 pcn1

v 

2

6.104

v  Z 2 pcn2

Average ratio chain:

u  n1 Z2

n2 Z1

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Checking the number of impact per second

To limit the impact kinetic energy E, the number of impacts per second is

defined as:

15

Z n

x

  [i] search in Table 5.6

Type of chain

Pitch of chain pc, (mm)

-Sequence of calculation and design the chain drives

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4 Calculating chain by resistance.

 Condition: The pressure generated on the contact surface of the pin and

hinge p must be less than the allowable pressure [p] of material wrapped

bushing

 Because of difference of experimental condition

[ ] F

A

0 [ ]

K

Pitch of chain

pc(mm)

Allowable pressure in hinge of chain[po], (MPa) rotating speed of

driving sprocket n1, (rpm)

31,75 ÷ 38,1 35

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29 26 24 21 21 17,5 18,5 15 16,5 – 15 – – – – – Sequence of calculation and design the chain drives

Allowable pressure[p0] search in Table 5.3

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5 F orce Analysis acting on shaft

Initial force F0

F0 = Kfqm a g (N)

Auxiliary Fv

Fv = qm v2(N)

Kf: Coefficient of chain deflection

+ Kf=1 for vertical position of chain drive

+ Kf=3 for angle smaller 400

+ Kf=6 for horizontal position of chain drive

qm: Mass of 1m chain (kg)

a: Centre distance (m)

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 Tension force in each side

F2 = F0 + Fv(N)

F1 = F2+ Ft (N)

Ft = 2T1/d1 (N)

5 F orce Analysis acting on shaft

 Force acting on shaft Fr

Fr = KmFt(N)

Kmis dependent on the angle between the center line with the horizontal line

+ Km=1.15 for angle smaller 400

+ Km=1 for angle from 400 to 900

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Q1:

Pitch of

chain

p (mm)

Allowable power [P], kW, rotating speed of driving sprocket n01(rpm)

12,7 0,35 1,27 2,29 3,13 3,86 4,52 5,06 5,95

12,7 0,45 1,61 2,91 3,98 4,90 5,74 6,43 7,55

15,875 0,57 2,06 3,72 5,08 6,26 7,34 8,22 9,65

There is two lines of Roller chain Transmission Power P1= 5,5 Kw and the rotating

speed of driving sprocket n1=380rpm Teeth on driving sprocket and driven sprocket

are Z1=23 and Z2=63, respectively The working condition coefficient K=1,8 Allowable

power of roller chain are given in Table 1

a Based on standard abrasion, determine pitch of chain pcof the chain drive

b Determine pitch circle diameters

Table 1 Allowable power of roller chain

Problems

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01

1

400

1,05

380

n

K

n

01

1

25

1,09

23

z

Z

K

Z

t x

K K K

K

a Determine pc:

+ 2 lines of chain: => Kx=1,7

+ n1=380rpm => n01=400rpm

select pc=19,05mm

[ ] 8,38 t

b Determine the pitch circle diameters :

sin (𝑍𝜋)= 𝟏𝟑𝟗, 𝟗𝑚𝑚

sin (𝑍𝜋)= 𝟑𝟖𝟐, 𝟐𝑚𝑚

n01=400rpm

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Roller chain drive has 2 lines of chain, pitch of chain pc=25,4; teeth on driving

sprocket Z1=23, Z2=63 Rotating speed of driving sprocket n1=380rpm

Center distance a=40pcand coefficient K=1,7

Determine:

1 Pitch circle diameters

2 Chain links

3 Maximum power P1(kW)

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Tiêu đề	Chain Drives
Tác giả	TS. Phan Công Bình
Trường học	Hochiminh City University of Technology and Education
Chuyên ngành	Theory of Machine and Machine Design
Thể loại	theoretical content
Năm xuất bản	2023
Thành phố	Hochiminh City

Định dạng
Số trang	11
Dung lượng	2,96 MB