IDENTIFICATION OF MACHINE TOOLS´ LOCATIONS
Bachelor Degree Project in Industrial Engineering Bachelor Level 30 ECTS
Spring term 2019
Students: Guillermo Águila Rodríguez Adrián del Álamo Alcalde
Supervisor: Wei Wang
Examiner: Kaveh Amouzgar
Abstract
The scope of this thesis will be focused on the machine FORMA Z1 which is one of the most functional amongst the sort of machines currently available in the market. It provides faster tool changes besides a huge variety of tool layouts with the possibility of making a product with one only set up. Furthermore, the combi-beam rotation capability, together with dual sets of tools, give to the machine an exceptional competence.
Through this project, some of the shortcomings in the usability of the machine are eval- uated to be able to give an accurate solution to provide it of extra functionalities, thus acquiring better efficiency during the performance. This solution consists of the develop- ment of a device which will aid the operator during the tool arrangement of the machine.
The solution includes a platform with a laser that will point out where the operator must place the corresponding tool. The system will know where to locate it because the real machine would generate an XML file which would contain all necessary data. All this data will be read by a computer and send it to the microcontroller that will control all the system.
The solution proposed improves the throughput and reduces the time needed in the bend- ing process increasing the facility in the process of bending metal sheet. However, there are some disadvantages on the implementation of this device. The new machine would be more expensive and the software would be changed to include the new system and the program that reads the XML document.
1For more information about the machine, visit https://www.cidanmachinery.com/products/
industrial/folding-machine/forma-z.html
Acknowledgements
We would like to express our gratitude to our supervisor Wei Wang to guide and help us during this project despite the difficulties to understand the complexity of this work, overall the last weeks of grand effort to make possible this project. Moreover, thanks to all his colleagues who contribute to the achievement of our goal.
We are also grateful to the University of Skövde (HIS) for covering all the costs of this project and for providing us with all the equipment and facilities.
Special thanks to the company CIDAN Machinery to give us the opportunity to carry out this project, and to help us when we need it.
Not forget to thank our friends and family who support us during all this work.
Contents
1 Introduction 1
1.1 Background . . . . 2
1.2 Problem Statement . . . . 4
1.3 Aims and Objectives . . . . 4
1.4 Limitations . . . . 4
1.5 Sustainability . . . . 4
1.6 Thesis Outline . . . . 5
2 Methodology 7 2.1 Design Methodology . . . . 7
2.2 Software Design Methodology . . . . 8
3 Frame of Reference 11 3.1 Laser Device . . . 11
3.2 PLC . . . 11
3.3 Raspberry Pi . . . 13
3.4 Arduino Boards . . . 13
4 Literature Review 15 5 Benchmarking 16 6 Building the Prototype 18 6.1 Initial Conditions . . . 18
6.2 Concept . . . 18
6.3 Work Procedure . . . 18
6.4 Design . . . 19
6.5 List of Components . . . 25
6.6 Assembly . . . 27
6.7 Programming . . . 28
6.8 Demonstration . . . 33
7 Results and Conclusions 34
8 Suppliers 35
9 Bibliography 38
Appendix A Code 41
Appendix B Datasheets 42
List of Figures
1.1 The radius varies depending on the distance between the clamping and the
folding beam . . . . 1
1.2 FORMA Z machine with a J-shape table . . . . 2
1.3 Example of tool layout . . . . 2
1.4 Table vacuum gripper . . . . 3
1.5 Machine’s tool arrangement for a 3-D piece . . . . 3
1.6 The Triple Bottom Line: People, Planet & Profit . . . . 5
2.1 Different areas of design work with system boundaries . . . . 8
2.2 V model . . . . 9
2.3 Solution model . . . 10
3.1 Laser line beam . . . 11
3.2 PLC Operating Cycle . . . 12
3.3 Raspberry Pi 3 Model A+ . . . 13
3.4 Arduino Mega 2560 . . . 14
5.1 Laser device as Virtual Navigator . . . 16
5.2 Laser beam line to aid placing the metal sheet . . . 16
5.3 Pneumatic pop up angle gauges . . . 17
6.1 Step-by-step work sequence of the prototype . . . 19
6.2 Positions where the system would be attached to the machine FORMA Z . 20 6.3 Motorized Camera Slider . . . 21
6.4 Motorized Camera Slider . . . 21
6.5 Communication between the Arduino board and Raspberry Pi . . . 22
6.6 3-D model of the prototype from top with an exploded view . . . 23
6.7 3-D model of the prototype from below with an exploded view . . . 23
6.8 Ultrasonic Sensor Bracket . . . 23
6.9 Structure which simulates the beam where the tools will be placed . . . 24
6.10 Tool of 1 cm . . . 24
6.11 Tool of 2 cm . . . 24
6.12 Tool of 3 cm . . . 24
6.13 Tool of 4 cm . . . 24
6.14 Tool of 5 cm . . . 24
6.15 Arduino UNO . . . 25
6.16 USB 2.0 Cable Type A/B . . . 25
6.17 Raspberry Pi 3 Model B+ . . . 25
6.18 5V/2.0A Micro USB Power Supply . . . 25
6.19 16GB SD Card . . . 25
6.20 HC-SR04 Ultrasonic Distance Sensor . . . 25
6.21 Mechanical Switch Endstop . . . 26
6.22 42BYG Stepper Motor with Me Stepper Motor Driver Module . . . 26
6.23 Quarton Laser Module . . . 26
6.24 9V/2.0A Power Supply Adapter . . . 26
6.25 Timing Belt . . . 26
6.26 Teeth Timing Pulley . . . 26
6.27 Wires Organizer Tuber . . . 27
6.28 Cable Ties . . . 27
6.29 Male to Female Jump Wires . . . 27
6.30 Male to Male Jump Wires . . . 27
6.31 Female to Female Jump Wires . . . 27
6.32 Prototype assembled . . . 28
6.33 Type of tools identified in the XML document . . . 31
6.34 SegmentSet identified in the XML document . . . 32
8.1 Industrial Laser Devices . . . 35
8.2 Motorized Linear Stages . . . 36
8.3 Industrial Ultrasonic Sensors . . . 37
1. Introduction
Since the beginning, CIDAN Machinery2 has been manufacturing machines capable of bending metal sheets. Due to its long experience performing within this industry, the company has secured an advantageous position. Therefore, this has led to becoming a very skilled and professional company whose success has allowed to expand the brand all over the world. Its continuous ambition of improving and growing leads to be more efficient in the achievement of bending a metal sheet.
Metal sheet is a very common part of many elements in construction, aviation or even automotive industry due to its characteristics or the immense possibilities to change its shape. Not only this but it could also be welded, cut or holed with different types of machines. Nevertheless, it will keep its strength and firmness. Hence, this material is typically used to make tough products with minimum thickness (R.G. Smith Company, 2014).
In terms of the bending action, the operation could be done manually or automatically.
The process consists of applying a force to one side of the piece whilst the other side is held by a device against some surface. Afterwards, this would cause a bend along the folding beam axis. However, the obtained edge would not be completely straight but rounded with a certain radius, which would be bigger or smaller depending on the distance between the clamping beam and the folding beam, giving the possibility of adjusting the radius with any thickness of the sheet (Sheet Metal Forming, n.d.). The Figure 1.1 reflects this idea.
Figure 1.1: The radius varies depending on the distance between the clamping and the folding beam (MetalForming Inc., 2018).
2For more information about the company, visit https://www.cidanmachinery.com
Nevertheless, if accuracy is being sought, it must be used a bending machine. On the case of the study, it is called folding machine. These machines consist of a backgauge table whose shape could be in several forms, allowing the operator to manage both large and small pieces without losing manoeuvrability (see Figure 1.2). It has different beams with their corresponding tools to hold or bend the metal sheets. In the Figure 1.3 can be seen the difference between them. The upper part is the clamping beam tools and the lower part consists of two sections equally segmented. The section on the left is the part that will hold the piece, the same as the clamping tools do. However, the right section is the folding beam tools which will do the bending action rotating along the beam axis.
It should mention that the tools are segmented and there are a wide variety of sizes.
Moreover, the table has some fingers that would pop up to force the metal sheet against them in order to ensure the correct orientation of the piece. (Heston, 2018b).
Figure 1.2: FORMA Z machine with a J-shape table (CIDAN Machinery Swe- den AB, n.d.a).
Figure 1.3: Example of tool layout (CIDAN Machinery Sweden AB, n.d.b).
It is known that bending a metal sheet could be a complex and time-consuming process.
For this reason, when a customer asks for a piece, the selection of a suitable machine must be as precise as possible to save time and costs. The purpose and the shape of that metal sheet will determine which machine suits better in the specific application. Indeed it would be chosen mainly by the kind of beam the machine has, and by the final shape and thickness of the piece. According to these facts, it is worthwhile to make a previous study of the part that will be produced.
1.1 Background
A folding machine can numerous several forms with a metal sheet. The procedure is similar in all sequences but changes the number of steps and the tool layout depending on the shape of the part. The operator can work with the piece from the front of the worktable or or from the rear, on the backgauge. Once there, the operator slides it and forces against the stoppers to lock it in the proper orientation. In addition, the table has
some vacuum grippers (see Figure 1.4) that will be activated to secure the piece in order to avoid displacement of the piece. After that, the operator needs to press a safety foot pedal to execute the first movement,and later to continue the sequence.
First, the table slides the piece forward the same distance as the height of the forthcoming flange. Now, if that side needs to be bent again, it will follow the same procedure auto- matically until all bends of that edge have been executed. Secondly, when the flange is done, the worker has to turn the piece to bend the other side. After that, the piece would have two flanges. The operator must check if the current tool arrangement is suitable for the next bending step. The operator has to verify if the folding beam tools will not hit the two flanges and if the clamping beam tool fits alongside the extension of the metal sheet that has not been bent. Therefore, the operator should remove, add or change the tools that are necessary in order to execute successfully the next bending operation (Heston, 2018a). In the Figure 1.5 is shown an example of tool layout taking into account the different flanges:
Figure 1.4: Table vacuum gripper (CIDAN Machinery Sweden AB, n.d.c).
Figure 1.5: Machine’s tool arrange- ment for a 3-D piece (CIDAN Machinery Americas, 2018).
The first bending sides are not difficult to bend in terms of tool layout because the whole piece is flat yet. However, when there are already two flanges, the clamping beam tools must fit as accurate as possible alongside the length of the piece that is still flat.
Furthermore, the folding beam tools have to be changed because they cannot collide with the flanges. Currently, the change of the tools is made manually by sight trying to get the precise position of the tools, that is why it could be installed some device that helps the operator during the sequence, ensuring the quality of the piece with the best possible efficiency.
The beam needs to over-bend the piece to achieve the 90-degree angle due to the spring- back effect (Heston, 2018a). This reaction is caused by residual forces remaining after a bending, leading to a small recovery of the form of the sheet after the force ceases (Sheet Metal Forming, n.d.). Therefore, there should be a gap between tools at the positions of both flanges of the metal sheet.
Otherwise, other feature of these machines is that are intelligent systems. They need to learn from the first bendings when it is trying to create a new shape. A worker has to
make the whole sequence, measuring the angle bent in each step and making the proper adjustments afterward. Thus, the system is storing all that information and then, the machine would manage that data to do the convenient corrections in future performings.
This process should be done several times until the results do not exceed the tolerances (Heston, 2018b).
1.2 Problem Statement
The main issue is the waste of time that takes the operators to arrange the tool layout before the machine starts the bending sequence. This task could be extremely time- consuming because the operator has to do it by sight and sometimes he has to change it again because it was placed wrong. Therefore, a helping device should be installed to aid the operator where to place each tool, thereby saving time during this task. If the tools do not cover all the length of the piece, it is only possible to leave some tiny gaps no bigger than 1 mm to avoid leaving a little mark, considering it as a defect.
The proposed solution should be an integral system that could communicate with the real machine. The machine generates an XML file which should read, and then, the data would be processed by the system to execute the corresponding task.
1.3 Aims and Objectives
The mission of this project is to develop a system which will be able to satisfy the purpose that the company needs. This equipment has to indicate the exactly location of the tools in the tool arrangement. A system will be created to meet these requirements. It will be an integral solution thanks to which the operator could rapidly see where to place the tools in the machine.
1.4 Limitations
In this project, it needs to be mentioned that the solution would not be installed in the real machine but a valid prototype would be built to test the functionalities. The reason why it would not be implemented in the machine is that it would be easy to install but difficult to connect it with the real machine despite it is a simple system. In addition, there would not be enough time to know how the machine is programmed and how to integrate with the software.
Nevertheless, with the goal of approving the proposed solution, the developed prototype will be tested and adjusted until it is validated.
1.5 Sustainability
In this project, sustainability is focused on the social area because it could help in the work conditions for the operators, as their task would be easier. The idea of sustainability was
starting to be heard when a concerning about the environment appeared. According to the United Nations Commission on Environment and Development (UNCED), sustainable development is development that meets the needs of the present without compromising the ability of future generations to meet their own needs (McKenzie, 2004).
Social sustainability should be equally important as the economic and the environment issue. This idea is reflected in the Triple Bottom Line concept. It is not possible to reach all the aspects at the maximum level but a balance between all three could be the solution (McKenzie, 2004). This relation is shown in the Figure 1.6:
Figure 1.6: The Triple Bottom Line: Peo- ple, Planet & Profit (Benojo Pty Ltd, n.d.).
This project consists of providing a solution to give a little bit more automation to the folding machine FORMA Z. The automation leads to the improvement in the labor condi- tions. Nowadays dangerous tasks are being carried out by robots and automatic machines, so these implementations have changed socially the life of many workers.
1.6 Thesis Outline
Below is described all the chapters this project is compound of, giving general information about each one. Starting with Chapter 1, which is previously presented, the preface of the field and the scope of the project are described. The next part is Chapter 2 which explains the procedure that will be followed to achieve the goals of this work.
Then, in the Chapter 3 will be explained some concepts taken on this project to make it understandable to every audience. With the Chapter 4, where similar studies or inquiries are investigated, ends the part in which an overview and a better knowledge of the subject are given.
The following part includes the practical resolution of the project. The Chapter 5 undertake an analysis of the competitors, searching the methods or techniques that they have used to solve the same problem. From this point, in the Chapter 6 is carried out the design and the construction of the prototype taking into consideration all the middle steps and the precautions at the moment of accomplishing this task. After the prototype is made, the results are examined leading to some discussion and conclusions in the Chapter 7. Finally, considering a future implementation, in Chapter 8 will be pointed out some suppliers who can provide the main components to create the real system.
2. Methodology
Through this project, a complete solution will satisfy all the functionalities required for the FORMA Z machine. The main goal is to design and implement equipment which will be able to guide the operator how to place the metal sheet in the machine and the tools in the clamping beam. This process has to be automatically. It will provide an integrated solution in which there will be communication between the machine and the system designed. The system will read the information the machine supplies and it will act subsequently according to the data.
In this part, the research methodology of the project is described. The procedures used to undertake this project are explained step by step with the methodology described in the following clauses.
2.1 Design Methodology
In this project will be included the development of the prototype design and the software for the control of the system. For the construction of the prototype, the design method- ology is used. This methodology consists of groups of activities which will be used for the development of technical systems. Nowadays, due to the tendency to work with comput- ers in the construction of prototypes, the design methodology has added the 2-D and 3-D graphical representation of the object.
The methodology used during this project will be followed as the Figure 2.1. In the beginning, the idea has to be developed. This idea has to contemplate all the tasks of the prototype since it has to be built with some specific characteristics. Once the idea of a prototype is clearly defined, the next step is the design of the idea.
Figure 2.1: Different areas of design work with system boundaries (Herbert Birkhofer, n.d.).
The design prototype is an overview of the system, which is made before starting to build the prototype. This task has the purpose of observing possible errors and fix them.
That is why it is a crucial step in the design phase. In the creative section, every detail is important because it should be functional but it also could be aesthetic.
Once the design satisfies the specifications, the building of the prototype begins. The first step is to know what are the materials needed for the design. The materials are really important in the prototype because give physical properties to the product and they should be selected carefully to accomplish the characteristics of the system. Finally, the assembly of the prototype has to be done. The assembly consists of putting all parts together and getting the final product (Birkhofer, 2011).
2.2 Software Design Methodology
This chapter explains the methods using in the design of the software. The design process describes the operations which affect the process and the interconnection between the activities. The operations that will be performed in this situation are the input of data, the output of outcomes and the participants.
The methodology used to create the programs is the “V model”, which is an industrial standard version of a “waterfall” model. This model is used for the explanation of the inputs and outputs of the design, dividing the design into two groups: architectural design and detailed design.
Architectural design focus on the structural problem of the model and it has the following characteristics:
• The organisation of the configuration of the items.
• Global management of the structure.
• Physical distribution.
• The protocol of communication synchronisation and data access.
• The selection of the characteristics of the components.
The detailed design would be defined as Hong Zhu mentioned: “Detailed design is con- cerned with the data structures and the algorithms to implement the functions of each component in the system” (Zhu, 2005). For the implementation of solutions, the structure shown in Figure 2.2 has been carried out in the project.
Figure 2.2: V model (Hong Zhu, n.d.).
The layout of the Figure 2.3 shows how to implement the solution:
• Developing different ideas for the solution.
• Build a model for each one.
• Compare the different models and appraise those which get better results in the original requirement.
• Develop the best design.
In this model, the three main keys of the sequence are:
• The number of iterations used to get a solution.
• The development of a model to evaluate the process in the design.
• The obtaining of different results to solve the issues of the design. After this, the dif- ferent solution is compared, and the best solution is finally chosen and implemented in the design.
Figure 2.3: Solution model (Zhu, n.d.).
3. Frame of Reference
The aim of this section is to define the subjects and hypothesis that are associated with the different parts of the project. These areas are the development and implementation of the laser device machine that implement the bending process.
3.1 Laser Device
The laser was created in 1960 and it is an acronym for ”Light Amplification by the Stimulated Emission of Radiation”. In a few words, a laser contains an atom or molecule inside that is excited with a light. Then, it is released another wave of energy which could stimulate the next atom or molecule, making a stimulation chain, so that amplifies the emission of the light (Hecht, 2008).
Laser device which purpose is the location function, has the light beam which is emitted from a lase device is concentrated into a single direction. In addition, it will be transmitted with an extremely tiny diameter along that entire line, although different kind of lens could be added to the end of the laser to get a specific effect. For instance, it could be a line beam such as in the Figure 3.1 (Silfvast, 2009). Nowadays, the laser could be used in many applications within different fields, widen the range of usability of this invention.
For instance, it is used both in construction, displaying a light beam to ensure the building is straight and flat, and inside small devices like DVD players. The value of the laser is highly demanded in a lot of areas (Hecht, 2008).
Figure 3.1: Laser line beam (Laser 2000, n.d.).
3.2 PLC
The developing of this project can be done with the implementation of PLC. The defi- nition of a PLC and its main features will be described as follows. It is an acronym of
”Programmable Logic Controller”. A PLC is a microprocessor-based controller with mul- tiple inputs and outputs.It uses a programmable memory to store instructions and carry out functions to control machines and processes. The PLC performs the logic functions of relays, timers, counters and sequencers (Collins, 2007).
The PLC hardware components include the following parts:
• CPU (Central Processing Unit): is the part of the PLC where the microprocessor is located. The microprocessor analysis the inputs signals and give outputs signals according to the program stored in the memory (Bolton, 2015).
• I/O Module: inputs are connected to sensors, push buttons switches that will give data to the CPU which will analyze these magnitude. Outputs will be connected to actuators, like pneumatic or hydraulic valve and done different tasks depend on the logic program state of the inputs (Bolton, 2015).
• Memory: provides storage to all data used by the device. The type of memory use in this hardware can be divided in two types:
ROM memory: keeps permanently read-only data such as the logic that will be executed to set the outputs (Bolton, 2015).
RAM memory: saves the status of all the inputs and outputs in each scan cycle (Bolton, 2015).
The operation cycle of a PLC is taking into a few steps. First, it does an internal scanning to check all the connections, communications and memory. Secondly, it reads all inputs and stores its status in memory. Then, it executes the logic program through which will set the outputs in the final step before it ends the entire cycle. This process will be running all the time (see Figure 3.2) (Gonzalez, 2015).
Figure 3.2: PLC Operating Cycle (Gonzalez, 2015).
3.3 Raspberry Pi
A Raspberry Pi is an inexpensive small computer with a strong potential to be operative as a normal PC, obviously with less capacity. It was created by the Raspberry Pi Foundation, an educational charity who wanted to spread the knowledge all over the world of how a computer works with a little complete device (Raspberry Pi Foundation, n.d.). It can be seen in the the Figure 3.3.
On the one hand, regarding the hardware, some of the parts of the board are the processor, an external USB port, Ethernet port, HDMI connector, and General Purpose Input and Output (GPIO) pins among others. On the other hand, regarding the software, there are a lot of options to use in the Raspberry Pi. As it has different requirements as a desktop computer, Raspberry Pi works with special distributions based on Linux although the official distribution is Raspbian. Linux is the most common operating system for this device because it is open source and it is free. In addition, the most known programming language used are Scratch, which is for beginners, and Python, for more greater skilled people in terms of programming. However, there are more options if these both are not the preferences of the user (Richardson and Wallace, 2015).
Figure 3.3: Raspberry Pi 3 Model A+ (Raspberry Pi, n.d.).
3.4 Arduino Boards
An Arduino board (the Figure 3.4 shows an Arduino Mega 2560) is an open-source platform with programmable hardware. It is easy and simple to use but makers can develop huge and complex projects with this microcontroller. The brand has gained tremendous reputation over the years since its manufacturing, creating a huge community where designers can share and help others. Due to its big popularity, many different types of boards have been invented generating a wide offer. This gives the possibility to acquire the board that suits better to the project (Evans, 2011).
It has an Arduino official software which is open-source and free to use. Moreover, people can build their own libraries and share with the community or can access the forum and
ask for some help if they need it (Wheat, 2011).
Figure 3.4: Arduino Mega 2560 (Arduino, n.d.).
4. Literature Review
Documents have been the primary source of data research for this report. The reference of books and articles are included in this project. This data collection gives information about previous or similar studies, i.e. hypothesis, processes or theories. These have been examined to know how the interfaces should be done or the information which is used for the correct implementation, among others.
Lasers in the industry have been used increasingly because they provide with high accuracy references to calibrate or for the buildings to ensure that the structure is straight. One of their functions is to emit a laser beam to help parts keeping aligned.
In the case of the article ”A laser alignment for boat assembly”, it mentions the use of a laser beam to emit a line to use it as a reference of the waterline when building the keel to improve the accuracy of assembly and avoid mistakes in the structure (Su and Rowlands, 2000).
A laser is also used to correct displacement of the shafts of the motor. It is used to align them in case there is a displacement of the shafts. There are two articles called
”Laser shaft alignment tool eliminates vibration” and ”Laser shaft-alignment tools” that support this idea (Higgins, 2000; Design, 2010). Therefore, lasers are used to the location or alignment actions due to its good accuracy.
Otherwise, the laser is used also in medicine for reconstructive surgery to project the mechanical axis of lower extremities to see the prolongation of the part. With this can correct a misalignment of those extremities of some patients (Hawi et al., 2014).
Furthermore, the laser could be used for very accurate alignments such as in the article
”The laser alignment system for the CMS silicon microstrip tracker” in which the accuracy achieved is micrometers (Wittmer et al., 2007).
All these articles confirm that the laser is very useful in terms of alignment because its accuracy ensures the desired position for the parts that are controlled. Therefore, as the operator needs a system that aids accurately in the tool arrangement and a visual device would be better to identify where to put the tools faster, the use of laser is justified.
5. Benchmarking
The object of an analysis of the competitors is to know the competencies of the other companies in order to have an overview of what they offer and see their strengths and weaknesses. This analysis only includes an inquiry of the methods of solving the problem statement previously mentioned in machines with the same or similar level of automation.
The names of the main competitors are RAS, Schechtl, and Schröder Group.
Firstly, RAS is using a Virtual Navigator (ViN) in its XTLbend model. It is a laser beam device (see the Figure 5.1) that emits a line reference in both sides of the clamping beam. It also moves along a parallel rail on the top of the clamping beam to cover all the length of the workspace. This device provides with great accuracy visual aid (see the Figure 5.2) which helps both the placement of metal sheet and tool identification.
Figure 5.1: Laser device as Virtual Navigator (RAS Reinhardt Maschinen- bau GmbH, 2018).
Figure 5.2: Laser beam line to aid placing the metal sheet (RAS Reinhardt Maschinenbau GmbH, 2018).
Secondly, the investigation of Schechtl’s machines resulted in anything relevant to interest since almost every machine has only a not-segmented clamping beam. Therefore, they would not need any tool identification and the operators do not need any suggestion for placing the metal sheet, thus the piece could be bent it in anywhere within the length of the table.
Finally, Schröder Group uses a similar machine named PowerBend Professional. It has a barrier and stoppers popping up from the backgauge to block the position of the metal
sheet and fix the orientation of the piece. In the Figure 5.3 they are pointed out in green.
Figure 5.3: Pneumatic pop up angle gauges (Schröeder Group, 2016).
6. Building the Prototype
6.1 Initial Conditions
Knowing the initial conditions is important before we start designing the model because they will probably affect directly to our concept. The main factor that will influence the future solution is the price. It should be as cheap as possible but without altering the functionality desired.
The solution is providing new functionalities to the machine FORMA Z (see the Fig- ure 6.2). It is a bending machine which has two setups for the clamping beam, one with a configurable layout and the other with a unique long clamping part. To switch between both, the beam has to rotate half a revolution.
6.2 Concept
Putting together all the information searched on the competitors and the problem de- scription the concept is developed taking into account the conditions and the possibilities of a future implementation on the machine. First, a brainstorming is carried out to get rough sketches of several solutions. During this process we realized that a laser system will be the best and the most accurate solution to indicate the position of where should be the metal sheet and the tools. Using laser, precision is ensured because it points out the location with a low tolerance, depending on the width of the laser beam. In addition, it displays a line reference with which the operator can know if he is placing the metal sheet or the tool in the correct spot. This laser will be moved alongside a rail system.
6.3 Work Procedure
The sequence of work that the system will follow would be, firstly, reading from the XML document generated from the machine in which the positions of the tool segments are included. Secondly, it should process that information and move the laser to the corresponding position. Then, wait until an external signal to point out the next position until all the tool arrangement is finished. Finally, follow the same procedure to help the operator in the placing of the metal sheet pointing out strategic spots to aid him in that task as seen in the Figure 6.1.
Figure 6.1: Step-by-step work sequence of the prototype.
6.4 Design
Since the clamping beam can rotate a 180-degree angle, the system could not be installed as in the Figure 5.1 because it is attached to the beam. Therefore, if it rotates, the laser will point upwards. To overcome this issue, the system would be designed as if it would be installed as in the Figure 6.2, thereby only one laser with a wide beam will be enough for this application. This makes the solution cheaper than the competitor who is using the same device because the system only has to power one laser.
Figure 6.2: Positions where the system would be attached to the machine FORMA Z (CIDAN Machinery Sweden AB, n.d.a).
The design of the prototype is based on ideas from several videos. The first overview of a possible design is something similar to the Figure 6.3. The video3 shows how to modify a manual camera slider to get a motorized slider. As this requires the assembly of some parts, an alternative should be found to create the infrastructure. It can be made of LEGO pieces or 3-D printing.
3https://www.youtube.com/watch?v=1ki-vVdqjng
Figure 6.3: Motorized Camera Slider (Maker, 2018).
Then, another video4 shows how to make a similar motorized camera slider with 3-D printing. The final design is based on the idea from this video: a system with two tubes whereby a platform will slide as seen in the Figure 6.4.
Figure 6.4: Motorized Camera Slider (Unknown, 2017).
At this point two ideas come up. On the one hand, a rail system with an all-in-one platform moved by wheels, similar movement like the trains. The platform would carry all the components. It would move by spinning the wheels, hence it would travel along the rail system to the position desired. However, the inconvenience is the weight because as it would carry all the elements, it would be too heavy and the motor would need to do more effort to move the platform. On the other hand, the platform would be moved by a timing belt instead. In this case, the motor could be on an extremity of the system and
4https://www.youtube.com/watch?v=1ki-vVdqjng
not in the platform. Moreover, it would be lighter and the motion would be transmitted better because the movement is applied directly to the timing belt optimizing the energy transmission. Whichever option is chosen, it will need an ultrasonic sensor to give feedback of the position is the platform in all moments. It also will include a limit switch to have a reference point in order to recalibrate the system if it is necessary or to move it there to be in a home position.
The controller could be whether a PLC or a Raspberry Pi. Considering that it is a prototype and there are not many inputs and outputs, a Raspberry Pi would be enough to test the system. Nevertheless, the real system installed in the machine would be controlled with a PLC. Using this device is also recommended because it is more maneuverable and smaller than PLC, hence it would be better integrated into the prototype and it would not add so much weight. Nevertheless, Raspberry Pi is basically a small computer and it has a huge capacity for computing but it is not the most efficient device to control the inputs and outputs. Therefore, adding a microcontroller, such as an Arduino UNO board, to take care of the I/O control would make the system faster and easier to wire. There will be a serial communication between both through a USB cable from the Arduino to the Raspberry Pi as seen in the Figure 6.5. They will exchange data from one to other to know the position where the laser has to move and also when it has arrived, among other information.
Figure 6.5: Communication between the Arduino board and Raspberry Pi.
The models of both devices will be, on the one hand, a Raspberry Pi 3 Model B+ because it makes easier the set-up of the board with the possibility of connecting a mouse and a keyboard at the same time. On the other hand, an Arduino UNO because it is the board provided by the university and it has enough pins to control the system.
At first it seems that LEGO would be easier because it gives more flexibility and more
configurable. Moreover, if it wants to make a change in the infrastructure, it will be simple to do it with LEGO pieces because it only requires to take off the pieces that are not necessary and put others. After doing some sketches about the design of the system adapted to the application of this project, the use of LEGO pieces was less viable because the structure of the system was becoming more complex and it would be difficult to find the specific parts to build the prototype. Therefore, 3-D printing would be the solution to make the infrastructure.
A modeling software, SolidWorks in this case, will be used to make the drawings. The final design can be seen in the Figure 6.6 and in the Figure 6.7. There are two extremities. Two metal tubes will connect both extremities. Through these tubes will slide a platform moved by a timing belt and two pulleys, one driven by the motor. The platform contains the laser, the ultrasonic sensor, and a limit switch which will be connected to the Raspberry Pi with a bunch of wire covered by a cable. Each element will be screwed, attached with cable ties or glued.
Figure 6.6: 3-D model of the prototype from top with an exploded view.
Figure 6.7: 3-D model of the prototype from below with an exploded view.
The design of the platform has been made to put the ultrasonic sensor in a bracket specific for it. Therefore, it also has to be modeled. The design of the ultrasonic sensor can be seen in the Figure 6.8.
Figure 6.8: Ultrasonic Sensor Bracket.
Furthermore, to make the demonstration of the prototype more understandable, a small structure and some small pieces will be printed to simulate the tool placement, that is
the task in which the laser will help the operator. On the one hand, there is the structure (see Figure 6.9) which will simulate the beam that will carry the tools. On the other hand, there are the tools (see Figure 6.10, Figure 6.11, Figure 6.12, Figure 6.13, and Figure 6.14) of different sizes to make the combinations more flexible.
Figure 6.9: Structure which simulates the beam where the tools will be placed.
Figure 6.10: Tool of 1 cm.
Figure 6.11: Tool of 2 cm. Figure 6.12: Tool of 3 cm.
Figure 6.13: Tool of 4 cm. Figure 6.14: Tool of 5 cm.
This will be seen better in the video demonstration in the Section 6.8.
6.5 List of Components
All materials are provided by the university and all the components (can be seen from the Figure 6.15 to the Figure 6.31) used in this project will be included in the following list:
Figure 6.15: Arduino UNO. Figure 6.16: USB 2.0 Cable Type A/B.
Figure 6.17: Raspberry Pi 3 Model B+.
Figure 6.18: 5V/2.0A Micro USB Power Supply.
Figure 6.19: 16GB SD Card. Figure 6.20: HC-SR04 Ultrasonic Dis- tance Sensor.
Figure 6.21: Mechanical Switch End- stop.
Figure 6.22: 42BYG Stepper Motor with Me Stepper Motor Driver Module.
Figure 6.23: Quarton Laser Module. Figure 6.24: 9V/2.0A Power Supply Adapter.
Figure 6.25: Timing Belt. Figure 6.26: Teeth Timing Pulley.
Figure 6.27: Wires Organizer Tuber. Figure 6.28: Cable Ties.
Figure 6.29: Male to Female Jump Wires.
Figure 6.30: Male to Male Jump Wires.
Figure 6.31: Female to Female Jump Wires.
6.6 Assembly
In this chapter will be explained the steps to assemble all the prototype. First of all, the metal bars will be inserted in the extremities to verify that they fit into the pieces. After this, the several parts of the platform will be put together with specific glue for plastics.
It must pay attention to the platform’s parts that will slide through the metal bars to avoid misalignment of the platform. Then, it should be attached the motor to the right extremity with the corresponding screws. In addition, it will fasten the pulleys on both
sides. On one hand, in the left extremity, it will be secured with another screw and a locknut. On the other hand, the right extremity, it will be secured to the shaft of the motor. Before continue, all the components that will be on the platform have to be glued.
This step is very important because once the parts have been stuck, it would be impossible to go backwards. The laser orientation must be perpendicular to the movement of the platform, therefore it has to put inside the platform carefully, knowing all the time where the laser beam will light. After that, the limit switch will be attached to one edge of the platform, so that it will contact with the right extremity. It will function as an end stop.
The last component to attach is the ultrasonic sensor, adhering it to its bracket so that it will point to the left extremity. Finally, the timing belt will be secured to the platform with cable ties to keep it tight. The prototype assembled with all the parts can be seen in the Figure 6.32.
Figure 6.32: Prototype assembled.
After the assembly is complete, the next step is wiring the electronic circuit. Each com- ponent will be connected to a specific pin (this will be shown in the code), and all the connections that require a HIGH level, which will be set at +5 V, will be connected in the same row of the breadboard to optimize the use of wires. The same to the connections that require a LOW level, set at 0 V. However each one will use a different row to avoid creating short circuits. Otherwise, the stepper motor will be wired as mentioned in the datasheet, which can be seen in the Appendix B.
6.7 Programming
All programs and files regarding the programming can be accessed by a link in the Ap- pendix A.
Before the programming part, previous tests will be carried out to check all parts work individually as expected before starting to work with the whole system. Afterward, they will be integrated into a single program where they will work together, thereby it ensures that a possible fault would not be due to a wrong or defective component but it would be only in the code.
First, the motor will be tested. The program will be simple, just to see if it works as the user wants. It will control the speed and direction of the motor. In this case, the values are non-variable integers, defining one value for clockwise direction and other value
for counterclockwise direction. The code of this program is based on the example of Me_StepperMotor library from Makeblock.
The file TestStepperDriver.ino makes basically the stepper motor spins in one direction at 1000 rpm for two seconds and then it spins in the opposite direction at the same speed, also during two seconds. To give time to the motor to change direction there is a delay of one second.
The ultrasonic sensor will be controlled by the use of interrupts. The interrupts are a tool to make the main code simple and also to enable running different tasks at the same time. They are activated when something happens in pin programmed as an input. The code that is have been used is from the author Steve Garratt. In the ultrasonic sensor program, some variables will be changed to adapt them to the variables of the project.
The file Ultrasonic_Sensor.ino, first, sets up the interrupts. On the one hand, a timer interrupt, attached to a function which will be called every period of time, specified in the setup(). On the other hand, a normal interrupt, also attached to another function which will be called every time the pin connected to the echo output of the ultrasonic sensor changes the state. Secondly, the main loop only will print the distance between the ultrasonic sensor and the object detected every 100 milliseconds.
Otherwise, there are several functions to help the code being simple and easier to read.
The function associated with the timer interrupt calls two other functions: trigger_pulse() and distance_flasher(). Trigger_pulse() activates or deactivates the trigger pin of the ultrasonic sensor to, then, the receiver can detect the pulse. This will happen every 200 milliseconds. Meanwhile, the function attached to the normal interrupt takes care of the measurement of the time that sound has traveled from the object. Finally, the distance_flasher() only creates a visual effect that when an object is close to the sensor, it flashes the on-board LED faster and slower when the object is more far away.
Finally, the communication between the Arduino and Raspberry has to be bidirectional, in other words, both will send data or information to each other. Therefore, they have to read and write through a serial communication. The serial communication will be tested.
The Arduino and Raspberry Pi will do a simple exchange of signals. Both programs should open a serial with the same data rate, 9600 bauds in this example. With these programs working simultaneously can be tested that both devices receive and send information to each other without any problem.
The Arduino program TestRaspduino.ino is waiting until receives some data through the serial, afterward, it reads that data and is stored in a variable. Then the Arduino writes in the serial that has received the information, which subsequently will be read by the Raspberry Pi to ensure that the data has arrived. After this, Arduino will turn the onboard LED on or off depending on the data received if it is an ’H’ or an ’L’.
Regarding the program in the Raspberry Pi called TestRaspduino.txt, it displays a message when it starts executing the code in which orders to write some command. When the user types it, the command is stored in a variable which will be written in the serial to enable the Arduino to read it. Next, the device waits one second to leave some time
to the Arduino to send the message and finally the Raspberry Pi displays on the screen what it has received from the Arduino.
Once all the elements have been tested, it is time to incorporate them into a single program. In a few words, the Arduino program is about moving the stepper motor until the platform has arrived at the proper position. The system will know when the platform is in position because there is the ultrasonic sensor giving feedback of the distance where it is. The platform will be moved to a reference given from the Raspberry Pi. It extracts the data from an XML file, generated by the machine FORMA Z. However, to test the prototype, position data of the XML document have been adjusted to be able to give coherent results. The reason for this is that the ultrasonic sensor has a reliable resolution in centimeters inside the range that the platform will slide, but it has not in terms of millimeters.
In the final program in Arduino called Prototype.ino, after to declare all the constants and variables, it starts the setup function where all the pins are defined as inputs or outputs. In this part, a timer, an interrupt, and motor parameters are defined. Other functions are the ultrasonic sensor measure, previously mentioned, the ”inicio” function which will move the platform to the home position (to the left extremity) once the system starts, then the ”diference” function which will return the distance between the reference and the actual position of the platform, there is also the ”Mdirection” function which will set the direction the platform has to move, and finally the ”wait” function which will make a delay during the specified period of time each time that is called. In the main function, it will do the function ”inicio” once, later Arduino will send through the serial an ”H” meaning that is ready to get a reference. It will wait until receives something from the Raspberry Pi. Once the Arduino receives some data, it will save it and transformed into an integer value minus 7 because it is the distance from the ultrasonic sensor to the laser. Therefore, if it wants to locate the laser above the reference received, the program should subtract 7. Now, it turns off the laser while moving and until the platform is not in the correct position it does not stop. When the sensor detects that has arrived at the position, a delay is made to ensure that is in the proper place. After the waiting time, the program checks if the laser is above the reference. In the case that is not, the platform will be moved again. This process will be repeated until the laser arrives at the correct location. In the case that it is in position, it turns on the laser and sends to the Raspberry Pi an ”L” meaning that the laser is in the correct spot. Now, the program will wait until the operator press the foot pedal, which is simulated by a switch. That means that the operator has placed the tool and needs the next reference to put the following tool. It finally waits again a period of time to ensure the communication and sends again an ”H”
meaning that is ready to get the next reference.
Otherwise, extensible Markup Language, an abbreviation of XML, is a subdivision of Standard Generalized Markup Language (SGML), which has been developing to provide a prime communication with SGML and HTML. The document XML describes the type of data objects, which includes the explanation of the characteristics of the program. The XML files consist of groups of storage data, whose basic unit of information is called entities. The entities are made up of either parsed or unparsed data. ”Parsed data is made up of characters, some of which form character data, and some of which form
markup. Markup encodes a description of the document’s storage layout and logical structure. XML provides a mechanism to impose constraints on the storage layout and logical structure” (Consortium et al., 2006).
An example of XML file which the company generated by the process planning of the folding machine is the document called Example.xml. This document includes all the information of the machine, tools, the type of material used, among many things. In the prototype, the information that is necessary is the ToolSet markup. Due to the lim- itations of the prototype, the XML document has been adapted to the capabilities of the system because the ultrasonic sensor can only measure with good accuracy distances in centimeters. Moreover, the prototype is smaller than the length of the real machine, therefore the numbers should be lower. The document adapted to the prototype is Infor- mation.txt. The structure of the document is the same but the data of the original file has been changed. However, the entities are adaptive for the model. The fundamental markups for the model are the ToolSet. Inside this markup, the ToolType means which beam tools are going to be defined. There are three different tools: BoxTool, FoldTool, and LowerTool (see the Figure 6.33).
• The BoxTool is the group of tools located on the top of the machine. The purpose of these tools is to hold the metal sheet whilst the bending action is carrying out.
• The FoldTool are located on the bottom of the machine and the aim of these tools is to fold the part.
• The LowerTool is next to the FoldTool and will be under the BoxTool when the metal sheet is going to be bent. Together with the BoxTool secures the metal sheet to avoid unwanted movements of the metal sheet when the bending action is happening.
Figure 6.33: Type of tools identified in the XML document.
Inside the SegmentSet part, the following information is available:
• MaxSpace is the limit space that could be in millimeters between segments.
• SegmentSet is a group of segments, which each segment is an individual tool (see the Figure 6.34). The folding machine usually has three sets of segments, divided by a large space between them, although two divisions could be possible too. Fur- thermore, the total width of each segment is determined in the file. However, that width is not the same as the sum of all segments because there are small gaps be- tween them. This division is due to the fact that on many occasions a tiny gap is needed for bending a part that has some flanges.
• StartPosition is the position where starts the segment set.
• Segment part indicates the width of each segment, the number of segments in that set, and the type of segment used. There are three types of segments depending on the position on the set. If the segment is in the edge of the set it could be Right or Left. Otherwise, it is Straight.
Figure 6.34: SegmentSet identified in the XML document.
The file Prototype.txt is the code that reads the XML document and extracts the width, type and number of the segments in each SegmentSet, and also the first position and the total width of the SegmentSet. Moreover, it makes a sum of all the widths. Then, the code subtracts this measure from the total width of the segment set. This new number obtained corresponds to the sum of the total spaces between the tools. Finally, this number has to be divided by the number of segments of that set minus one to get the width of each gap. Therefore, this distance is added to the final position of each tool to send the position of the next segment, letting some space between tools. The position where must be placed the segments will be sent to the Arduino which will be in charge of moving the motor to locate the laser above the corresponding spot.
Also the type of the segment is important because there are three types of tools, in box tool, the outside tools could be right or left, and the inside tools are straight. The left
