Chap.10 Design Process of Kinematic Scheme of the Mechanism System

发布于:2021-06-11 03:07:53

Chap.10 Scheme of Mechanism system

Chap.10.1 Review Design Process Chap.10.2 Design Process of Kinematic Scheme of the Mechanism System

Chap.10.1 Design Process
Problem Definition

Concept Generation
Concept Selection

Why?
What?

Iteration

Embodiment Design

Which?
Detail Design Fabrication Evaluation

How?

Chap.10.2 Design process of kinematic scheme of the mechanism system

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Process Example

Design process
working principle of the machine

Motion forms analysis
Type synthesis of the mechanisms Cooperation design Dimensional synthesis of mechanisms Evaluation Kinematic diagram of the mechanisms

Redesign

Working Principle of the Machine
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?

Step1

Gear cutting: form cutting and generating cutting Sheet transmission machine:

Creation & conclusion

Motion forms analysis
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Step2

Analyze and decompose the motion which machine needs, think out the motion forms. ? Method: imitation, creation

Creation & conclusion

Type synthesis of the mechanisms
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Step3

Choose, combine into or create the mechanisms Principle: satisfy the requirements, choose mechanisms as simple as it can be, limit the size, choose suitable kinematic pairs, consider the drivers, good dynamic characteristics, be adjustable, be safe

Cooperation design

step4

Cooperation of the function, time and space.

To ensure the cooperation of working links, the working cycle diagram is drawn. It is a time table for the actions of all the working links. 1.Principle 2.Method 3.Working cycle diagram

Principle
1.

2.
3. 4.

Operation Order(sequence of actions) Step and cycle Layout and no interference Efficiency and less energy.

Method
1. Working

cycle 2. Working time of the each mechanism 3. Motion cooperation

1. Transmission 2. Rotation and intermittent 3. Translation up and down 4. Filling Lotion

Rectilinear working cycle diagram

Circular working cycle diagram

Rectangular coordinate working cycle diagram

Working cycle diagram

Evaluation

Step6

Indexes of evaluation 1) System function 2) Working performance 3) Dynamic performance 4) Economic performance 5) Structure, size, weight, complexity 6) Layout

Example-Shaping machine
working principle of the machine
Motion forms analysis Type synthesis of the mechanisms Cooperation design Redesign

Dimensional synthesis of mechanisms
Evaluation Kinematic diagram of the mechanisms

Working principle of the machine
Cutting plains ? Mill (铣) ? Plane (刨) ? Grind (磨)

Motion forms analysis
Two main motions and requirement:
1) Cutting cycle 2) Feeding cycle 3) Adjustment of the system Relative reciprocating motion between the cutter and the workpiece. The stroke should be adjustable.the velocity of the motion should be uniform. The feeding motion in the direction perpendicular to cutting motion. The feeding motion should be adjustable

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?

Type synthesis of the mechanisms
?
?

Cutting motion Feeding motion

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Selection of mechanisms for cutting

Selecting feeding mechanisms

Cooperation design

Dimensional synthesis of mechanisms

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Use the methods we taiked in the above chapters

Evaluation
Principles 1) System function 2) Working performance 3) Dynamic performance 4) Economic performance 5) Structure, size, weight, complexity 6) Layout

Kinematic diagram of the mechanisms

Homework
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? ? ? ?

?
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某自动机采用一个电机驱动,经过减速后驱动输送带、转盘间歇分度机构、冲 头2和卸料杆1完成对毛坯3的输送、定位、加工和卸料等工艺动作,理论生产 率为20个/分,其工艺动作为: 1)由输送带和转盘间歇分度机构将毛坯3送到*台4上,冲头2开始下行; 2)经过0.8秒后冲头2接触毛坯3,又经过0.2秒后,冲头2将毛坯3压缩到指 定的尺寸,停歇0.4秒后,冲头2开始快速返回,至原始位置,等待下一个循环; 3)在冲头2开始返回的同时,卸料杆1亦开始动作,经过0.8秒后将毛坯送到 指定位置,然后用0.5秒退回到原停歇位置,等待下一个循环。 请完成以下设计任务: 1)绘制该自动机的运动循环图 2)设计冲压机构(含冲头2),绘制其机构运动示意图,提出至少两种方案; 3)设计卸料机构(含卸料杆1),绘制其机构运动简图,提出至少两种方案;

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