Sheet metal die components

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Die is a special tool used to change shape of sheet metal by cutting and non cutting actions.
In the process of designing a die for a particular required specimen, you need to understand the basic sheet metal die components. There are many types of die which are used in the sheet metal operations.

Die plate

This is a part to which all the parts of die are attached so basically this is an elementary hub to connect all parts of die. It is made of steel. Die plate size depends on the required product after operation in the die.

Die set

An assembly which consists of both die shoes is called die set.

Shoes of die

There are two Types of shoes in the die. Upper shoe and lower shoe. These two shoes are combined together with the help of Guide pin. The shoe thickness is directly proportional to the expected force to apply on the die during operation.

Guide pin, bushing, back gauge

These are the components to guide the tool towards the required direction. These parts ensures how the tool is going in the same position in every stroke of operation in the die. Basically the parts establishing an alignment between upper and lower part of a die. These components are of two types, friction pins and ball bearing pins.

Heel blocks and heel plates

These parts are employed in the die to absorb the side thrust (if any) that generates in the die during operation. The Precision is required while machining these objects while making the die.

Screws

Screws are the components to join the various working parts and components together i.e. Upper part and lower part of die are fastened through screw. Socket head is the most common screw for dies. 

Keys

Keys are rectangular blocks machine with high precision dimension for a hole. Keys are to be inserted in the Milled key way sections or pocket holes in the shoes of the die.

Dowels

Dowels are the types of pins used to fix the sections to a desired location precisely on the die shoes.

Pads 

Pads in the die are the plates employed for pressure loaded on the die during the operation it hold and control the metal.

Spools

Pads used in the die needs to be fastned with the shoes. For that purpose, the spools are the components to be used. 

Spring

To supply the appropriate force from press to die to complete the operation, the various types of springs are used. The life of spring and force required are the factors that needs to be considered while selecting an appropriate spring.

Guide post

This is an important part that connect the upper die shoe to the lower die shoe. It is a hard metallic rod connected by using the bushings in upper and lower die parts. Guidepost plays the key role to guide the punching tool towards the specimen to perform the operation.

Guide post bushings

Guide post bushing is a hollow part made of steel inside which the guide post travels in sliding motion. 

Punch

Punch is the main tool for cutting or forming operation to get the desired product. It is attached to the upper die set in a Press machine. This tool Contacts to the specimen and shape it as per the requirement. Both type of operations i.e. Cutting or forming are performed using this tool.

Stripper plate

Stripper plate used to hold the specimen on the die when tool cut off or strip the material.

This is all about the sheet metal die components. For a tool design engineer these are the basic fundamentals about the die preparation in the tool room. The automobile industry uses these manufacturing processes in a very wide market. Both conventional or unconventional manufacturing methods needs die along with press machine or with CNC or VMC machines. Every parts of sheet metal die components are to be designed to get a working die to manufacture a desired product by cutting or forming operations.

Lower Pair and Higher Pair

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In the study of theory of machine there are many basic terms to understand. The basic motive of studying theory of machine is to learn machine building. For that purpose there is a need to understand the elementary terms or parts that indulge in the machine building process. These elementary terms are kinematics chain, links, joints, degree of freedom, constraints etc. 

The kinematic pair is very important aspect to understand in theory of Machines.
The classification of kinematics pair, the most important one is based on the point of contact. On that basis kinematics pair are of two types. These are Lower pair and higher pair

Lower pair

When two elements of a pair are joined together with the surface contact between them the joint is called lower pair. Area of two elements comes together when relative motion occurs between the elements to form a lower pair.

The elements has sliding motion mutually in a lower pair because of surface contact. Basic kinematic pair like prismatic pair, revolute pair, screw pair, are some examples of lower pair.
lower pair

Lower pair joints

The joints which comes under lower pair are described with degree of freedom and there motions with that joint.

Prismatic joint
is a lower pair which has one directional translatory motion and has degree of freedom = 1. This means Prismatic joint has constraint in 5 directions.

Revolute joint
has one directional rotational motion and therefore degree of freedom =1. The three translatory and two rotational motions has constraints in the revolute joint.

Screw joint - this is a special case. Screw joints has translatory and rotational motion but both are not independent. When screw rotates with the threads, it also moves in linear motion because of threads. Its degree of freedom is calculated =1.

Cylindrical joints has one rotation and one translation independently. So its degree of freedom is 2.

Planar joints has one rotation and two translatory motion. That is why its degree of freedom =3.

Higher pair


Higher Pair

In The higher pair, only one point or line are responsible to form a joint between two links. The elements of higher pair must have curve in its shape. These joints are found in the cylinders or spheres of equal or different radius which have their axis parallel to each other. A cylinder or sphere lying on a flat surface has a point Contact and makes a higher pair. The relative motion of cam and follower makes a point Contact between them. The point of contact between two involute gear meshing makes a higher pair. These are some basic examples to explain the higher pair better.

What is Rigid Body or Rigid link and What is Kinematics of Rigid Body

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The study of rigid body or rigid link is a subject of mechanics. Lot of studies can be done on rigid bodies. Rigid body kinematics and rigid body dynamics are the subject of analysis to understand the nature of a rigid body . The rigidness of a body is desirable while making kinematic links in a machine or structure.
Rigid body rotation

Define rigid body

A Rigid body is one which do not change its shape or size on the application of force. While force is applied on the rigid body very small change in shape that is negligible can happen.It means rigid body possess high stiffness property.In other words we can say that a body which do not deform on the application of force is called rigid body. The distance between two atoms remains same on applying the force in rigid body as it was without any force.

When a solid body is taken as in ideal form it is called rigid body so we can say that the perfect rigid body do not exist in the reality. Some solid body which has very few deformation on the application of force is considered as rigid body. Due to this idealization the rigid body is considered to have uniform mass distribution. To understand the behavior of rigidbody i.e. Dynamics and kinematics of it, you have to understand the Euler’s equations.

Kinematics of rigid body

In the Kinetics of rigid body the position of a rigid body and the moment of rigid body are the aspects to cover.

The position of rigid body

The position of all the particles of rigid body is the position of rigid body as a unit. The analysis of three non-collinear particles in a rigid body is enough to covers whole rigid body position for analysis.
The position of rigid body deals with two categories
Linear position and angular position

Linear position

It is the position of a point in the body which coincides with the centre of mass of the body. The position is represented by a vector.

Angular position

It represents the orientation of the body. To understand the orientation of the rigid body Euler's equation should be considered. This equation helps to observe the motion of rigid body in a coordinates system.

Velocity of a rigid body

Velocity of a rigid body also have same categories as the position of rigid body i.e. linear velocity and angular velocity.

Linear velocity

The change in the position of a rigid body with respect to time is called linear velocity. It is a vector quantity. The linear velocity is calculated when the body has no rotational motion in it because if the body has rotation then the instantaneous velocity of two particles might not be same.

Angular velocity

Angular velocity is the change in the orientation to describe the angular speed of a particle in the rigid body. It is a vector quantity. When rotation in a rigid body takes place, all the particles in the body feels the identical angular velocity.angular velocity is not the rate of change of angular position.

Rigid body rotation

The change the position of a rigid body (i.e. Linear and angular position) with respect to time is called the rotation of rigid body. the diagram given above explains the terms or factors involve in the rotation of a rigid body.

Rigid body dynamics

In the rigid body dynamics the study of application of external forces rigid body is carried out. It is basically the study of behavior, motion, kinematics, kinetics etc. of a rigid body under external forces.

As the deformation do not takes place in the body as per the assumption of the rigid body, it simplifies the analysis of rigid body dynamics by reducing the parameters for consideration for analysis.


The analysis is carried out with the help of laws of motion  and laws of kinematics. These laws explain the position, speed, and acceleration etc of a rigid body with respect to time.

Examples of rigidbody.

As the stiffness is main factor of a rigid body so we can choose some materials as rigid body which has higher stiffness. Some examples of material with higher stiffness are diamond, steel, rock, cast iron etc.

5 Best Books of Robotics

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Hello everyone. Today I am enlisting 5 best books for robotics. Nowadays, Robotics engineering is on peak. New researches and innovations are coming in a very frequent manner. The robotics even become a separate branch of engineering. Beside this many branches of engineering has a special subject of robotics in the course curriculum, whether it is mechanical, computer science, electronics, electrical engineering etc. robotics is a system which is a combination of these core engineering.
In the list of books given below the first three books is higher level books because these books start from basic theory and goes up to development phase with programming in robotics. Although the beginners can also prefer these books because there is a lot to learn in the field of robotics.
Last two books are based on building a real robot practically. These books do not have much theory part because the main focus is about building a robot. So it demonstrate all the requirements for this purpose.

1.Introduction to Robotics: Mechanics and Control

by John J. Craig  (Author)

This book explains the robotics up to the development level. Generally the book is recommended for the one who wants to develop a robotic system i.e. book focuses on the application part. The students of robotics engineering must read this book.
The mechanical control and movement manipulation is described vey well. The book is consist of programming problems which is important to develop a robot.
In the new edition of the book a chapter of MATLAB is included. MATLAB is a simulation software used to test and simulate a model. In the robotic it may be beneficial to have the knowledge of MATLAB.
The book covers almost all the important aspect of robotics i.e. mechanics, control sytem, computer science, programming etc. most of the chapters are bases on mechanical manipulation or mechanics.
The book is helpful for graduate level student to an engineer of robot development.



2. Robot Building for Beginners, (Technology in Action) 

by David Cook (Author)


It was the best-selling books when the first edition as released. The best part of the book is, the book do not focuses much on the theory part of the robotics. The readers do not need to study those heavy engineering terms. The book is based on building a robot practically.
The various materials and tools required to build the robots are described in a simple manner. The books start from right here. Then the book explains how to make the prototype and then how to build the body of robot. Finally the whole system is built by making the circuit board to control the system.
The extract of the book is that you will learn the whole process of building a robot by building it by yourself, practically.

3. Industrial Robotics - SIE: Technology - Programming and Applications

    by Nicholas Odrey

This book is simply awesome and don’t need enough word to be explained how helpful this book is.
The book is the complete guide of building the robot.The book has in depth analysis of fundamental of Robotics. The book is mainly targeted to the beginners.
It focuses on technology, programming and applications of industrial robots which helps the readers in transition from classroom and lab environment into the applied and practical world of industry. the book offers different methods to build different types of robot because the book is featured with basic programming. The book is designed for learners and for beginners and for those who do not have any experience of robotics.

4. Probabilistic Robotics (Intelligent Robotics and Autonomous Agents series)

by Sebastian Thrun  (Author), Wolfram Burgard  (Author), Dieter Fox  (Author)


This is one of the best book of robotics. It covers almost all aspects of robotics and embedded system development. One can understand the robotics from basics by this book. This book is important for all the people associated with robotics field, whether they are teachers, students, engineers, developers, researchers etc. The book has explained advanced methods of estimation theory and probabilistic models. The various techniques and algorithms are given of relevant fields. The chapters are featured with many examples to understand the thing easily.

5. Robotics: Modelling, Planning and Control (Advanced Textbooks in Control and Signal Processing) 

by Bruno Siciliano and Lorenzo Sciavicco


The book mainly focus on the modelling of the robotic system and movement control of the robot modelling means the frame structure or the foundation of the robot. The book very finely demonstrate how the thing works in the robots. So the book is for application part of robotics. The various types of problems are explained in the books related with motion planning, motion control etc. the book also have the basic topics of mechanics like actuators and sensor, kinematics etc.
The book includes the chapter of MATLAB. This can be beneficial for those who want to learn simulation along with the robotics and embedded system.




This is it. The list is completed. Choose the appropriate book for yourself, learn about robotics and become the part of this world of innovation and revolution. the books enlisted here are bit expensive for Indian users but if you have passion to join the world of robotics then these are the best books of robotics..

What is Constraints and Types of Kinematic constraints

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In the theory of machine when we are familiar with basic mechanism, kinematic links, kinematic pairs, etc. There is very important topic that we should be aware of. Degree of freedom and kinematic constraint. These are very important criterion to consider during machine building. Degree of freedom and kinematic constraints are opposite things. But to understand one we have to understand another also. This Article mainly focused for kinematic constraints, so that would be elaborated here.
four bar mechanism with constraints


What is the meaning of kinematic constraints is described in the following definition.

Define constraint

kinematic constraints are the restrictions for a link in the motion of a machine.
Constraints are the inverse of degree of freedom. As the degree of freedom is about how many directions and axis an element can move.

What would be the inverse of it - How many direction and axis an element is restricted to move. This criteria will known as kinematic constraints.

Any element can move in three translatory direction and three rotational direction. So the maximum type of motions an element can have will be referred as degree of freedom and the maximum motion that an element is restricted for motion can be said as degree of constraints.

If a system has degree of constraints then it will hold the system rigidly. To make a body rigid the degree of constraints should be higher and the degree of freedom should be constrained.


Types of constraints

There are mainly two categories of kinematic constants
1. Holonomic constraints
2. Non holonomic constraints

Holonomic constraints

These Constraints arise from joints cam joints, hinges, sliding elements etc. Holonomic constants also called geometric restrictions.These constraints are responsible for the construction of a system

Non holonomic constraints

The constraints which are applied on the movement velocity of any system  are called non holonomic constraints. The common examples of this type of constraints are, rolling without sliping, knife-egde constraint etc.

Examples of kinematic constraints

Constraints are very basic criteria of mechanism formation. some basic examples are given below

Kinematic coupling

In the kinematic coupling all the translatory and rotational degree of freedom are constraints.

Kinematic chains

The primary body of a mechanism is called link. This link is rigid in nature. Links connected by kinematics pair are called kinematics chain. the degree of freedom of a kinematic chain can be calculated by formule. So the constraints in the kinematic chains are also measurable.

Kinematic pairs

Kinematics pairs are formed by creating a joint between links. There are many types of kinematic pairs. Kinematic pairs help the system to implement the constraints in a mechanism.

Rolling without slipping

When an object rolls in a surface without slipping, the velocity of the centre of mass will be cross product of angular velocity and a vector from the point of contact of the centre of mass.

Constraints Equation

In the algebraic form the equation of kinematic constraints can be written as
                                               F=F(q)
Where q Is the vector of body coordinates and f is the function of kinematic constraints.
On differentiation of this equation, vacation will become
                                                •
                                                F= Dv
Where D is the matrix and v denotes the velocity.

Again we differentiate this equation and it will be
                                                 ••    •    •
                                                 F= Dv +Dv
       •
here v Represent the acceleration.
let
                                                        •
                                                 J = -Dv
           
then                                             •
                                                 Dv = J
                                                                 •
the equation can be solved in terms of v and v can be calculated by any generic method.

These equations are used to find out the constants of any system. Kinematic analysis are carried out with the help of these equations.

Advantages of kinematic constraint



  • Smooth motion in the machine system.
  • Increasing the stability of mechanism.
  • Increase rigidity.
  • Better control on the motion of links of mechanism.

Conclusion

So in the analysis of kinematic system, kinematic constraints are very important criteria to consider. The analysis of kinematic constraints can provide better results to control the mechanism or motion in a system.

Kinematic Pair, Classification of Kinematic Pair

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The basic understanding of kinematic pair and its types is very important for mechanical engineering students. this is just the starting of theory of machines so you should know about its definition and its classification. kinematic pairs are classified based on some categories. You need to be aware all of them without any confusion.
kinematic pair    image source

What is Kinematic pair

In a mechanism or a machine, when two links or elements are joined with some type of contact, the combination of these two elements is called kinematics pair. The motion between the elements of pair should be completely or successfully constrained. The theory of kinematics pair is very important in the field of machine building. In the kinematics pair, the relative motion between the element has the key role for selection of an appropriate type of pair for a specific machine.

In the theory of machine to understand that type of kinematics pair is very important.There is a Classification of kinematic pairs based on different categories which are described below.

Type of Kinematic pairs

The type of Pears is defined as following considerations

1. Based on Nature of contact

Lower pair

When two links are joined with an area or surface contact between them, then the pair of links is called lower pair. In the relative motion of these two elements of the pair, elements slides on one other surface.

Sliding pair in crank slider mechanism, screw joint, shaft in a hole, pin joints are some of the example of lower pair.

Higher pair

If there is a point contact between the joints of two elements of pair, the kinematics pair is called higher pair. In the higher pair both turning and sliding motion are present partially

 For example, if two spheres are connected then they will have point Contact. The ball bearing are usually connected with point Contact. In the toothed Gears meshing with each other, that type of contact is point contact.

2.Based on nature of mechanical constraint

Closed pair or Self Closed pair

In the closed pair the elements are held together mechanically. The relative Motion is possible between the elements in the closed pair. All The lower pairs are closed pairs and some of the higher pairs comes in the category of closed pair. In the two elements of closed pair one is necessary to be a hollow part in which other element will be inserted. This is also called self closed pair. The example of closed pair is a Prism sliding on a hollow part.

Unclosed pair or Force closed pair

In the unclosed pair, the external force is required to keep the element of a pair connected to each other. Due to this unclosed pair is called force closed pair. The pair is not held mechanically in the unclosed pair. The example of enclosed there is cam and follower mechanism.

3. Based on the type of relative motion between the links

Prismatic Pair or Sliding pair 

When the elements of a joint constitute in such a way that one element can slide in the other element relatively. This kinematic pair is called sliding pair. Since in a sliding pair one type of relative motion so it is completely constrained motion between the links.

Sliding pair is generally a lower pair. Crank slider or Piston cylinder mechanism, prism sliding on a hollow part are the examples of sliding pair.

Revolute pair or Turning pair 

If the element only have capability to revolve inside the other elements in a fix access then the kinematic pair is called turning pair. In this pair also, the completely constrained motion will be there.

Lathe spindle revolves in the headstock, the bicycle wheel rotates with respect to a fixed axis, a shaft in a bearing. These are some of the examples of turning pair.

Rolling pair

When one element has rolling motion by keeping other element fix then the pair is called rolling pair.

Examples: a wheel rolling on a flat surface, roller bearing, ball bearing.

Screw pair

When screw Threads are provided in an element and one element can move along these threads, then the kinematic pair is called screw pair.

For example nut and bolt, lead screw in the lathe.

Spherical pair

In the spherical pair one link is fixed and other will be in the shape of sphere. The spherical element will turn on the fixed link.

The example of spherical pair is ball and socket joint.

Cylindrical pair

If the elements has both linear and turning motion then the pair can be said as cylindrical pair.

So that is all about the kinematic pairs and its classification. This topic is very important in theory of Machines. The basic mechanisms start from here. You Should be well aware of kinematic pairs to understand the basic mechanism like four bar mechanism, slider crank mechanism, double slider mechanism etc. Because as I mentioned earlier the mechanisms and the machines are built with the combination of links and the links are joined through pairs. So the kinematic pair is basics during the analysis of machines. 

Cutting Operation on Sheet Metal

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the cutting operations in the sheet metal is basically done on press machine. for cutting a material a tool is required. the tool is designed through the analysis of the final product requirement. there are many types of operations and for many operations there are many types of tools. based on the product design the strength, dimensions, material and capacity of the tool is decided during tool design. here we will discuss all basic cutting operations of press machine. the cutting causes due to shearing action in the sheet metal by press tool.

Cutting Operation In Press Machine On Sheet Metal 

The operations in which sheet metal component is divided into several parts is called cutting operations. Some important cutting operations are given below-

Blanking

This is most basic cutting process in the sheet metal. In which the punching tool mounted on press machine is imposed or pressed in the sheet metal to cut the material. In blanking the punched part will be the useful product and the remaining material with hole will be the scrap part.

Piercing

The operation is same as blanking process. In this process the holes are cut by press machine. But in piercing the punched part will be the scrap and remaining would be useful product. so it can be said that it is inverse of blanking process.

Notching

when the material is removed from the edges of the sheet metal the operation is called Notching. The press is imposed and scrap is removed by cutting action from the edge of the specimen.

Parting Off

In this cutting process material is removed from one specimen to make two useful products by cutting action.

Nibbling

In this process the successive holes are created by punching. The required size of sheet is created through punching. This is done when the die to cut the sheet is not available or the size of required product is large. This process can also be done by drilling the holes in the specimen.

Cut Off

If the cutting action is done along a line, it is simply referred as cut off.

Lacing

In this cutting operation, the material is not removed totally from the specimen. In a rectangular cut three side cutting operation is done. The remaining side is used for bending.

Cropping

This is cutting action to control the movement of the strip.

Perforating

In this cutting process, maximum holes are tried to cut in a single stroke in press machine. This is a kind of piercing process to cut maximum holes in the flat sheet metal. Series of piercing operations is performed in a single stroke.

Trimming

This process is to remove the extra unwanted material from a drawn component, when some material is unwanted in the work piece.

Louvering

This process in a combination of cutting and forming operations. In this one edge is operated with cutting action and three edges are cut by forming operation.

Shaving

This is a finishing operation to be performed on the blanked or pierced parts. the tool for this operation is different from other press operation tools.