PROIECT

Universitatea Tehnica din Cluj-NapocaFacultatea Constructii de MasiniSpecializarea: Robotica EnglezaAnul: 3

ProiectIngineria Roboticii

Student:

Molitorisz Andor

1

Modeling of a robot screwdriver

Content:

1. Process description…................................................................................p. 32. Description of three constructive versions of robots…………………….p. 73. Selecting one construction version of a robot…………………………...p.164. Determining the drive type……………………………………………....p.235. The calculation of the motor power……………………………………...p.236. CAD design of the robot ……………………………. (CATIA V5R19) p.297. Detailed design of the robot components……………..(CATIA V5R19) p.318. Verifying the structure……………………………….............................. p.379. References………………………………………………………………..p.38

1. Process descriptions

2

The robotized application consists of an automated screw driving cell that uses a robot to mount printed circuit boards (PCB) into electronic machines.

It is a very useful application reducing the time and increasing the productivity. Robots provide tremendous flexibility. Indeed, robotic screwdriving makes it easy to do quick changeovers and run small, varying size batches of related assemblies. Robots can drive screws from all directions, sometimes with varying torque requirements. They also have the ability to drive different sizes of screws using various feeders for each type of fastener. When an operator handles the parts in a manual or fixed screwdriving application, fixture accuracy is often not as critical. In fact, ‘fixture accuracy' can be detrimental to manual throughput. With robotic applications, however, the assembly [must be] brought to the robot for true automatic throughput. That requires constant part security during transfer phases and rigid support at the drive locations.

The screwdriveing assembly applications typically consist of multiple operations that a controller coordinates:

Part LocationPresenting parts to robots. In the past parts needed to be precisely fixtured

so that the part is always in the same position and orientation. This is expensive, time consuming and doesn’t allow for flexibility when the part type or size changes.

This includes parts that are loosely fixtured, parts that are presented on a conveyor and in some cases parts in a box or bin.

Part Fastening or JoiningPart fastening/joining is a critical part of many assembly operations. After

all, the nature of assembly is bringing multiple parts togetherForce SensingForce sensing is often needed for insertion or tightening operations. A

force sensor provides feedback to the robot control system and can measure forces and toques being applied at the end-effector. The feedback loop is closed very quickly (typically at 1 ms) so that the robot can pause when a desired force is achieved or alter the direction of the robot.

3

The work cells main components are the controller, the robot, the conveyor, the screw feeder system, the automatic screwdriver and the automatic part placer (Pick and Place part placer).

The parts where the circuit boards will be screwed are brought in by a conveyor that places the part exactly in the place where the robot can find it with the help of an optical laser sensor.

The robot’s end-effector consists of a specialized automatic screw driver.The ‘’pick and place’’ part placer puts the PCB it in the right location

where the tool, the automatic screwdriver will mount it on to the part. The main component of the screwdriving system is the programmable screwdriver with a torque range of 0.7 to 4.2 newton-meters.

The robot picks up a screw from a screw feeder using a vacuum to pick it from a separating nest. If necessary, screws can be preloaded in a magazine or a track to get them to the moving driver or it can use a Blow-Fed Screwdriver technology that is more faster.  These are fed by a standard DEPRAG screwfeeder, which consists of a vibratory drive, a spiral-track bowl and a screw separator. After exiting the bowl, the screws are blown through a tube to the nosepiece of the screwdriver. The robot moves to each joint and installs a screw to the correct place. Then, the robot returns to the starting position, and module exits the cell.

The screws are tightened in a two-step process. The screw is first threaded in at a slow speed and then tightened to a preset torque (minimum 1.2 newton-meters, maximum 1.8 newton-meters). Once torque has been reached, the screwdriver stops automatically. The screw is seated securely every time at the same torque, with a maximum standard deviation of 3 percent. Each screw is installed in 1.3 seconds. This process is monitored by the controller, which is integrated with the central control system of the assembly cell. The unit drives the tool’s brushless electric motor, operates the tool remotely, controls and monitors the screwdriving process, and collects and stores data on the assembly process. This is the task of the screwdriving robot.

Cartesian robots (Fig.5) are best suited for automated screwdriving applications. In many applications, Cartesian systems simply will not reach, or you cannot bring the parts being assembled. Larger robots offer greater working

4

footprints and have greater flexibility to take on multiple tasks, such as material handling, adhesive dispensing or inspection simply by changing end effectors.

Cartesian (Fig.5) and SCARA (Fig.3, Fig.4) robots are often used for screwdriving applications. These robots are less expensive and are usually faster than their articulated cousins, which most manufacturing engineers associate with material handling, painting and welding applications.

But, with the right type of end effectors and feeders, six-axis robots can also be used as fast, flexible screwdriving tools. Because they provide articulated motion that closely resembles a human, six-axis robots are ideal alternatives for many screwdriving applications.

Unlike Cartesian robots (Fig.5), which have a rectilinear work envelope, or SCARAs (Fig.3, Fig.4), which have a cylindrical work envelope, six-axis robots (Fig.1, Fig.2) have a spherical work envelope. An articulated robot can reach above, below, around and behind itself. Its wrist can rotate a fastening tool or turn it on an angle.

Six-axis robots offer agility and long reach, and they can handle complex part geometries. However, articulated robots are not as fast as Cartesians and SCARAs, and they're more expensive. Manufacturing engineers must decide if a screwdriving application justifies the trade-offs.

Robotic screwdriving offers numerous advantages, such as accuracy, repeatability and flexibility. 

Six-axis robots

Fig.1 Fig.2

5

SCARA robots

Fig.3 Fig.4

Cartesian robots

Fig.5

6

2. Description of three constructive versions of screwdriveing robots

Version 1: The KUKA KR 5 sixx serial robot (Fig.6)

Maximum speed in minimum space: the KUKA Small Robots are ideal for nearly all applications that call for utmost precision and rapidity, such as for handling delicate components. Special tools can be easily adapted, as all the energy and fluid supply lines are integrated into the robots so that there is no restriction on the axis motion ranges.

All of the Small Robots are also optionally available as a dust- and splash-proof variant, allowing protection ratings of up to IP 65 to be achieved. A further strength is their user-friendly and service-proven KUKA controller.

This assures system compatibility with other KUKA models, provides a uniform control concept across the entire range, and enables fast commissioning and simple maintenance.

The advantages: high planning reliability and security of investment. Extremely fast – extremely flexible

Whether mounted on the floor or ceiling, as the standard model or in the special variants Cleanroom (CR) or Waterproof (WP) – the KR 5 sixx gives you high precision: with repeatability rates of up to ±0.02 mm. Thanks to its low weight and fist-shaped work envelope, it performs its work quickly and flexibly even in confined spaces – with a reach of up to 850 mm and a payload of up to 5 kg.

The advantages: increased output and flexible production. Extremely durable – extremely productive

These robots offer you more: integrated routing of the energy supply system for air and I/O signals significantly reduces the wear – thereby extending the maintenance intervals. At the same time, special brakes prevent the axes from sagging under gravity when the robot is switched off. This means that the robot is always ready for operation, and you save time and money.

The advantages: lower maintenance and major time savings.

Extremely cost-effective – extremely precise

7

Automatically better: with a KUKA robot you not only have all process steps under control, but also benefit from top performance and flexibility. Thanks to pioneering robotics and control technology, you can rely around the clock on maximum precision – as well as on ease of operation, simple space-savingintegration into production sequences, and availability rates of almost 100%.

The advantages: production with greater precision and lower costs. Extremely simple – extremely versatile

The simpler your robot is to program, the quicker you can get going. KUKA supports you with a wide range of products and services: from expandable system software and readymade application software to simulation programs for designing systems. Programming is made easy with the familiar Windowslook, intuitive user interface and clear visualization.

The advantages: maximum ease of operation and rapid commissioning.

Fig.6

KUKA KR 5 sixx serial robot specifications

8

Tab.1

Version 2: LR Mate 200iC serial robot (Fig.7)

9

Basic DescriptionThe new LR Mate 200iC Series is FANUC Robotics’ next generation, electric servo-driven mini-robot series offering best-in-class performance in a light, efficient, accurate and nimble (LEAN) package. The LR Mate 200iC’s tabletop size, slimmer arm profile, lighter weight, highest dexterity, faster sustained speed and superior positioning accuracies make it the perfect solution for countless industrial and commercial applications. LR Mate 200iC, the Solution for:

Machine tending Material handling Assembly Picking and packing Part washing Material removal Dispensing Testing and sampling Education and entertainment

Features and Benefits 5 or 6 degrees of freedom ±0.02 mm (200iC & 200iC/5H) and ±0.03 mm (200iC/5L)repeatability at full payload and full speed within

entire robot work envelope Up to 5 kg payload at wrist Best-in-class wrist moment and inertias for real-world EOATs and work

pieces Pneumatic and electrical (6 RDI) connections for EOAT conveniently

located on J4 Two, double-acting solenoid valves integrated in forearm simplify EOAT

dress out Highest joint speeds maximize throughput Tabletop size, slim wrist, and small footprint permit operation in tight

work spaces Robot can flip over backwards for a larger work envelope Enclosed mechanical design eliminates cables and hose snagging

10

Upright, angle, wall or invert mounting increases installation flexibility Higher rigidity and the most advanced servo technology enable smooth

motion without vibration in high speed operation Advanced communication capabilities via standard Ethernet and serial

connections Integrated PMC provides ladder-logic control for peripheral devices Lighter and more compact than its predecessor The arm profile cross-section area is 42% smaller than the previous

generation LR Mate 200iB Same footprint and wrist bolt pattern as previous generation for easy

upgradesRobot Reliability

The latest generation of a proven design Sealed bearings and brushless AC motors Standard “C” size batteries for encoder backup Grease fittings on all lubrication points for quick and easy preventive

maintenanceRobot and Controller Options

110 VAC single phase input voltage 360-degree J1 axis rotation Fail-safe mechanical brakes on all joints Available R-30iA Mate rack mount compact controller fits in standard

19” electronics rack and is ideal for climate controlled applications such as food, lab, pharmaceutical, medical and education

iPendantTM, a color, Internet-ready teach pendant for even easier programming and custom cell user interface design

Extended networked I/O capabilities: I/O Link, DeviceNet, Profibus Supports a variety of intelligent functions including iRVision® (built-in

vision ready controller) and force sensing Available IP67 rating for the entire robot allows it to withstand harsh

environments 7 m or 14 m controller-to-robot connection cables Available Class 100 and Class 10 cleanroom option on 200iC/5C and

200iC/5LC

11

Available 200iC/5F food grade robot for primary and secondary food handling Unique Software Options

Patented real-time singularity avoidance Collision protection Internet connectivity KAREL® programming language Many more software solutions for control, communication, and motion

Fig.7

12

Tab.2

Version 3: Motoman YS 450-4 -axis SCARA serial robot (Fig.8)

13

YS-series 4-axis SCARA robots are ideal for high-speed handling and assembly systems; same controller as other Motoman® robots allows easy integration.

High-Speed SCARA RobotsThe YS450 4-axis, SCARA robots offer high speed in a compact form

that requires minimal installation space. The YS450 model features a reach of 450 mm, Z-axis stroke of 170 mm and 5 kg maximum payload. The YS-series robots feature an IP20 rating and offer superior performance in applications such as assembly, part kitting, small part handling, case packing, lab automation, and magnetic media and semiconductor processing. These robots easily integrate with existing robot applications to expand current automated processes. They are ideal for large, multi-process systems requiring pick-and-place capability. YS-series robots feature the same NXM100 controller used with Motoman Robotics’ small six-axis robots (HP3M-series and HP6M series).

NXM100 ControllerThe compact NXM100 controller easily fits underneath conveyors or the

controller cabinets can be stacked to provide floor space savings.

Fig.8

14

Tab.4

15

3. Selecting one construction version of robot

With the right type of end effectors and feeders, six-axis robots can also be used as fast, flexible screw driving tools. Because they provide articulated motion that closely resembles a human, six-axis robots are ideal alternatives for many screw driving applications.

The industrial robot suitable for our application is the second version the 6 axis Fanuc LR Mate 200i robot (Fig.9) with a Blow-Fed Screwdriver as end-effector.

Fig.9

16

The LR Mate 200iC Robot series offers the smallest models within the FANUC Robot range, with up to 5kg payload. These Robots are ideal for fast and precise applications in all environments. They run on the R-30iA Mate compact controller, which requires minimum space.

INTEGRATED END EFFECTOR SERVICES

Pneumatic and electric cabling to the valves placed near the flange, increasing system reliability

Two standard integrated double acting air solenoids (3rd valve available as option)

FLOOR, CEILING, ANGLE AND WALL MOUNT POSSIBLE

Robot can be mounted on the floor and on the ceiling without any restrictions, angle and wall mounting possible (with restriction)

Better use of space within envelope

VERY HIGH THROUGHPUT LR Mate 200iC

The LR Mate 200iC brings:

Calculated TCP speed of more than 4 meters/sec

SEALED MECHANICAL UNITS

Robot can be mounted inside the machine tool

Reduced installation costs

"SEVERE DUST LIQUID PROTECTION (SDLP)” WITH COMPLETE IP67 AS STANDARD

Robot entirely IP 67: Dustproof and can be immersed in water

17

COMPACT ROBOT DESIGN

Easy to integrate into a work cell

Reduced floor space

Less interference area

Reduced investment

SMALL COMPACT CONTROLLER

R-30iA Mate as standard

LR Mate 200iC/5H: COST-EFFECTIVE 5-AXES UNIT

The LR Mate 200iC/5H offers a cost-effective solution for every application where axis J4 of the LR Mate 200iC is not necessary.

LR Mate 200iC/5C AND LR Mate 200iC/5LC: CLEANROOM VERSION

Special treatments for cleanroom (color, covers, bolts, seals, etc)

Changing solenoid valves and air joints to cleanroom type

Exhaust port for solenoid valves on J1 base

Features cleanroom class 100

MOTORS DIRECTLY COUPLED TO THE REDUCER

Simplified mechanical unit

Reduced breakdown risk

Compact and reliable solution

High accuracy and minimum backlash

18

FLIP OVER CAPABILITY

Reduces cycle time

Allows more flexible cell designs

Allows several robots to work together in close proximity

Full working envelope when robot mounted upside down

No interference with robot itself

For a more efficient means of production to improve the assembly process we can consider integrating a Fanuc robot, because, these robots can be outfitted with a variety of special heads to adapt to any process. Screw driving, Adhesive Dispensing, Welding, Parts Pick & Place, are just a few of the unlimited numbers of processes where Fanuc Robots can help save you money and increase productivity.

An articulated robot can reach above, below, around and behind itself. Its wrist can rotate a fastening tool or turn it on an angle. Six-axis robots offer agility and long reach, and they can handle complex part geometries.

The movements that the robot arm makes to complete the assembly are the following:

19

Fig.10

20

Fig.11

Screwdriving the top (Fig.10)

1. Initial position2. Screwing the PCB to the product. Upper joint

2.1 Moving from J2, J3 forward2.2 Turning from J1 left, J5 positions the screwdriver in the right place2.3 Turning from J1 right, J5 positions the screwdriver in the right place2.4 Returning to the forward position (2.1)

3. Screwing the PCB to the product. Lower joint3.5 Moving from J2, J3 backward3.6 Turning from J1 left3.7 Turning from J1 right3.8 Returning to the backward position (3.5)

Initial position

Screwdriving the side (Fig.11)

8. Initial position9. Screwing the lower side. J1 turns left, J2, J3 backward, J4 turns and J5 positions the screwdriver in the right place10. Screwing the upper side. Keeping the J1 and J4 position from J2 and J3 the robot leans forward and J5 positions the screwdriver in the right place.

21

The end-effector tool

Fig.12

Blow-Fed Screwdriver is fed by a standard screwfeeder, which consists of a vibratory drive, a spiral-track bowl and a screw separator. After exiting the bowl, the screws are blown through a tube to the nosepiece of the screwdriver. The robot moves to each joint and installs a screw to the correct place. The screws are tightened in a two-step process. The screw is first threaded in at a slow speed and then tightened to a preset torque (minimum 1.2 newton-meters, maximum 1.8 newton-meters). Once torque has been reached, the screwdriver stops automatically. The screw is seated securely every time at the same torque, with a maximum standard deviation of 3 percent. Each screw is installed in 1.3 seconds. This process is monitored by the controller.

22

4. Determining the drive type

The vast majority of robots use electric motors. AC motors are rugged, robust and low cost. These modern motors give higher power output and are almost silent in operation. As they have no brushes they are very reliable and require almost no maintenance in operation.

By definition servo motors are motors integrated with a control system that enables precise positioning. So, usually, servo motors can rotate to a given angle, not continuously. Basically, the servo system could include also other types of motors, such as pneumatic or hydraulic as long as the feedback system is present to provide positioning. Unmodified they are great to construct robot arms and other things where a precise angle is needed. A servo motor operates on the principal of "proportional control." This means the motor will only run as hard as necessary to accomplish the task at hand. If the shaft needs to turn a great deal, the motor will run at full speed. If the movement is small, the motor will run more slowly. AC servos can handle higher current surges and tend to be used in industrial machinery.

The drive type that is used for the screw-driving robot is the Brushless AC Servo Motors, which are directly coupled to the reducer.

• Simplified mechanical unit• Reduced breakdown risk• Compact and reliable solution• High accuracy and minimum backlash

5. The calculation of the motor power

23

Fig.13

A0=5kg W 1=1.5kg L1=50mm

A1=1kg W 2=1.5kg L2=40mm

A2=1kg W 3=5kg L3=280mm

A3=1kg W 4=3kg L4=40mm

A4=1kg W 5=5kg L5=300mm

A5=2kg W 6=5kg L6=200mm

A6=2kg

T 1=L1× A0+12L1×W 1=0.2875Nm

24

T 2=(L1+L2 )× A0+12

(L1+L2)×W 1+L2× A1+12L2×W 2=0.6175Nm

T 3=(L1+L2+L3 )× A0+12

(L1+ L2+L3 )×W 1+( L2+L3 )× A1+12

(L2+L3 )×W 2+L3× A2+12L3×W 3=4.1175Nm

T 4=( L1+L2+L3+L4 )× A0+( 12L

1

+L2+ L3+L4)×W 1+( L2+L3+L4 )× A1+( 12L2+L3+L4)×W 2+(L¿¿3+L4)× A2+( 1

2L3+L4)×W 3+L4× A3+

12L4×W 4=4.8175Nm¿

T 5=(L1+L2+L3+L4+ L5 )× A0+( 12L

1

+L2+L3+L4+L5)×W 1+ (L2+L3+L4+ L5)× A1+( 12L2+L3+L4+L5)×W 2+(L¿¿3+L4+L5)× A2+( 1

2L3+L4+ L5)×W 3+(L¿¿4+L5)× A3+( 1

2L4+L5)×W 4+L5× A4+

12L5×W 5=11.5675¿¿

T 6=(L1+L2+L3+L4+L5+L6 )× A0+( 12L

1

+L2+L3+L4+L5+L6)×W 1+ (L2+L3+L4+ L5+L6 )× A1+( 12L2+L3+ L4+L5+L6)×W 2+(L¿¿3+L4+L5+L6)× A2+( 1

2L3+L4+L5+L6)×W 3+(L¿¿4+L5+L6)× A3+( 1

2L4+L5+L6)×W 4+(L5+L6 )× A4+( 1

2L5+L6)×W 5+L6× A5+

12L6×W 6=17.4675Nm¿¿

T P1=T 1+T2=0.905Nm

T p2=T3+T 4=8.935Nm

T 5=T p3=11.5675Nm

T 6=T p4=17.4675Nm

ɷ j6=720 deg/ s=¿12.56 rad/s

ɷ j5=450deg /s=¿7.85 rad/s

ɷ j4=450deg /s=¿7.85 rad/s

ɷ j3=400deg /s=¿6.98 rad/s

ɷ j2=350deg /s=¿6.1 rad/s

ɷ j1=350deg /s=¿6.1 rad/s

25

PA12=T p1×ɷ j6=113.66W ≈ 200 W = 0.2 kW (Tab.5 - 60TXA 00630E)

PA34=T p2×ɷ j5=701.39W ≈ 750 W = 0.75 kW (Tab.5 – 80TXA 02430E)

PA5=T p3×ɷ j2=705.58W ≈ 750 W = 0.75 kW (Tab.5 – 80TXA 02430E)

PA6=T p 4×ɷ j1=1064.2W ≈ 1050 W = 1.05 kW (Tab.5 – 130TXA 05020E)

Brushless AC Servo Motors performances and dimensions

26

Tab. 5

Fig.14

27

Fig.15

6. CAD design of the robot and robot cell

Robot dimensions

28

Fig. 16

29

Fig.17

Robot in CatiaV5

Fig.18

Robot Cell

30

Fig.19

7. Detailed design of the robot components

31

2-DOF orientating mechanism constructive solution

Fig.20

Kinematical scheme of the mechanism

Fig.212-DOF orientating mechanism in Catia V5

32

Fig.22

1. Taper gear with flange type end 12. Double single row ball bearing 13. Needle bearing 14. Housing (Case)5. Shaft 16. Single row ball bearing 17. Taper gear 18. Needle bearing 29. Single row ball bearing 210. Taper gear with flange type end 211. Taper gear 212. Shaft 213. Single row ball bearing 314. Double single row ball bearing 215. Taper gear 3

33

Taper gear 3 Taper gear with flange tyend 1

Fig.23

34

Taper gear 1 Taper gear 2

Fig.24

35

Taper gear with flange type end 2 Shaft

Fig.25

8.Verifying the structure

36

9. References

37

Blebea Ioan - Solutii moderne in c-tia robotilor - Editura U.T. PRESS 2006

Stefan STAICU, Iulian TABARA, Ovidiu ANTONESCU - KINEMATICS AND DYNAMICS OF A 2-DOF ORIENTINGGEAR TRAIN

Prof. dr. ing. Aurel JULA, Prof. dr. ing. Dorin DIACONESCU Proiectarea constructiva a sistemelor mecanice ale produselor mecatronice – Editura Universitatii"TRANSILVANIA" din Brasov

http://www.preciseautomation.com/Kinematics.html http://www.societyofrobots.com/ http://www.kuka-robotics.com/en/ http://www.abb.com/product/us/9AAC910011.aspx http://www.motoman.com/ http://www.fanucrobotics.com/ http://www.assemblymag.com/articles/87493-assembly-automation-

robotic-screwdrivers-assemble-auto-parts http://www.assemblymag.com/articles/84182-robotic-screwdriving http://www.weberusa.com/home.php http://www.youtube.com/watch?v=coyeGlP9lsk http://www.flexibleassembly.com/Products/Robotic-Screw-Driving-

Systems/LR-Mate-200iC-5L http://www.pic-tronics.com/Robot-Arm-Torque-Tutorial.php http://www.dac-us.com/assembly/assembly.html http://www.3xmotion.com/english/default/index.asp http://www.directindustry.com/

38

39