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Automatic Boarding Machine Design Employing Quality Function Deployment, Theory of Inventive Problem Solving, and Solid Modeling

| On 19, Jan 2000

(Excerpt from Masters Thesis)
By
BENJAMIN K. KUNST
Graduate Student
College of Textiles
and
Dr. TIMOTHY G. CLAPP, P.E.
Professor
College of Textiles

North Carolina State University
Raleigh, North Carolina
1999

3.3. Concept Generation using Theory of Inventive Problem Solving, TRIZ

3.3.1. Introduction

TRIZ, pronounced “trees”, is the Russian acronym for Theory of Inventive Problem Solving. TRIZ is used to assist those that must be innovative or creative in their field. Put simply, TRIZ uses a number of tools to make innovation methodological and systematic. The view of creativity as being an erratic or random event no longer exists for TRIZ users. Three ideals structure TRIZ theory: 1) the ideal design is the desired end result, 2) contradictions assist problem solutions, and 3) innovation can be an organized systematic process. TRIZ moves innovative thought away from being an art and toward a science.

Genrich Altshuller, a Russian scientist, began developing TRIZ in 1946 while he was a patent clerk. While reviewing patents he found patterns and commonalties in the solutions given. Initially, Altschuller reviewed some 40,000 patents. Over time more than four million patents from the world patent base have been reviewed.

Altschuller discovered that there was a finite problem set within the patent base that could be defined when the patent’s technical language was reduced into generic terms. These problems fall into three classifications: technical, physical, and administrative. He also realized that there were a finite number of solutions for the problem set. While many of these solutions varied across different fields of research, the methods applied were the same. These findings developed into what is known today as Contradiction Theory.

Altshuller’s third discovery was that there common patterns in the evolution of technical systems. He found that the subsequent development of a system after it was first invented had a number of similar stages. The tools derived from this discovery became known as the patterns of evolution.

Trial and error methods are the most inefficient techniques for generating innovative solutions in comparison to TRIZ methods. Inventing using trial and error can use a vast amount of resources such as time, effort, and money. Even worse than the use of resources is the unpredictability. One trial could be performed before a solution is found, which is unlikely, or there could be literally thousands of trials with no acceptable solution. An analogy to using trial and error methods is baking a cake multiple times to perfect it instead of using the cookbook which is TRIZ.

Paradigms are a negative result of the psychological inertia of an inventor. Removing the paradigms set over time through experience was a goal of Altshuller. Problem solving paradigms can be viewed as tools in the toolbox of an inventor. The size of the toolbox is dependent on the experience of the inventor. The problem associated with using this toolbox is that no matter how intelligent, wise, or talented the inventor, the size of the toolbox is limited. If the inventor’s paradigms are temporarily dropped, the use of TRIZ allows them to use knowledge built in the world patent data base from thousands of inventors over hundreds of years. This removes the inventor from his/her current knowledge base and into the entire world’s knowledge.

Work on TRIZ is continued today outside of Russia in the US and the rest of the world. Many tools and theories have been developed in addition to Contradiction Theory, including Ideality, Functional Diagramming, Su-Field Analysis, ARIZ, Patterns of Evolution, and Anticipatory Failure Determination™ Ideation Corporation. All of these tools will be discussed in the next chapter. Ideality, Functional Diagramming, and Contradiction Theory will be emphasized because of their use in the boarding automation project. The last part of this section, 3.3.6, will discuss the implementation of TRIZ in the boarding automation research.

3.3.2. Ideality

In 1956, researchers formalized the observation that designs evolve over time to the ideal solution. Most people would initially define the ideal solution as using the least energy, having the fewest parts, causing the least amount of friction, etc. If these definitions were taken a step further the ideal design would provide the function while not being physically present at all. The ideal design satisfies all the requirements of the customer by using already available resources. This theory of driving toward the ideal solution with intention became known as Ideality.

Ideality can also be defined in mathematical terms:
Ideality = (Sum of Useful Effects) / (Sum of Harmful Effects + Cost) (3.1)

This equation can be used in combination with functional diagrams to express a level of Ideality. It can be seen that either increasing the numerator or decreasing the denominator or by changing the relative growth rate can influence the level of Ideality. Decreasing the denominator, or removing harmful effects, is the most beneficial change to the system. Increasing the number of useful functions to increase Ideality may results in increased use of resources.

There are two approaches for obtaining a near ideal design: Use of Resources and Use of Effects. Resources, in this case, are substances or fields that are readily available. They can be used in combination or independently to accomplish the desired function. Available resources include energy reserves, free time, and unused or empty space [6]. Effects can be physical, chemical, and geometric. Effects can also be described as natural phenomena such as hot air rising, thermal expansion of materials, and gravity. Of course, most of these effects are unknown to any one scientist because they cross fields and backgrounds. There are more than 250 physical effects, 120 chemical effects, and 50 geometric effects. Over three thousand different effects have been identified to date.

Each of the six paths, listed below, provide a means for moving towards Ideality.

  1. Exclude auxiliary functions

  2. Exclude elements

  3. Identify self-service

  4. Replace elements, parts or total system

  5. Change the principle of operation

  6. Utilize resources

Initially it appears that the theory of Ideality would be extremely helpful when trying to redesign an existing system. However, Ideality, has direct applications in the initial stage of design. Considering how to implement available resources and natural occurrences will surely improve the design process. Setting goals, such as a certain weight or cost, other than ideal will eventually limit the designer.

3.3.3. Problem Formulation – Functional Diagramming

Functional Diagrams are simple cause and effect graphs used to show the interactions between process functions or product parts or a mixture of each. The definition of the functional diagrams remains loose so that the user may mold the problem into a useful and helpful form. Diagrams can have varying hierarchies. They may be very large and complex if the user desires, encompassing every “nut and bolt” or can remain simple, containing only the surface functions of the system.

Traditional TRIZ tools did not include functional diagrams. Later, in 1992, Zusman and Zlotin added “Formulator”™ Ideation Corp. [6] to assist in the use of traditional TRIZ tools such as Contradiction Theory. Since 1992 software forms have been added for easier charting.

elements may be harmful or useful. Useful functions may have varying degrees of capability ranging from insufficient to excessive. A component of a machine could be a mounting plate. A useful action of that component could be that it holds another component in place. It could have the harmful effect of placing excessive gravitational load on the mechanism moving the component. A supersystem element is an element that impacts the system that is beyond the control of the designer. The product is the result of the process. Figure 3-6, below, is a functional diagram of a typical system.

Figure 3-6: Typical Functional Diagram

Gaining a deeper understanding of a system can often solve many problems without employing additional tools. A powerful use of functional diagrams is system comprehension through reviewing component connections and relations. Quality Function Deployment and Analytical Hierarchy Process can be used in combination with functional diagrams to identify the most important technical problems. Communication can also become greatly enhanced because the system is shown in an easy viewed graphical format.

When the system is fully understood, simplification should begin. Trimming is the process of removing components and actions. Trimming moves the product/process closer to the Ideal Final Result. Removing harmful actions would be the biggest benefit to a system. Harmful action should be eliminated, reduced, or prevented using traditional science. If the action may not be removed, there may be a way to benefit from it. Useful actions and thus components should be removed by finding alternative actions. Finding an alternative method may remove multiple unnecessary functions. If no better alternative solution is known, a way to enhance the action or component should be researched.

Contradictions may be seen easily using diagrams. Any component that is required for a useful action but also causes a harmful action is a contradiction as shown in Figure 3-6. Contradiction Theory, discussed in the next section, can be used to find a solution that will cause no harmful effect.

3.3.4. Contradiction Theory

Contradiction Theory was one of the first tools developed by Genrich Altshuller. Using this tool will allow the user to generate multiple solutions to any given contradiction. Contradictions are split into three categories: physical, technical, and administrative. The first two types of contradictions will be covered in the following paragraphs while the third, administrative does not apply TRIZ tools. A typical administrative contradiction would be a need for a larger budget while little cash is available.

Physical contradictions exist when there is some part of a design, system, product, etc. where two conflicting states are desired simultaneously. For instance a soft drink bottle should be, both large and small; large for capacity and small for ease of transportation. A consumer could also desire a stove that is hot to heat food and yet also cold to the touch for safety purposes.

Three separation principles are used to solve physical contradictions: separation in time, space, and scale. In the soft drink example, separation in time can be used. If the container were collapsible it could be large at one time, during use, and small at another time, when transported. Separation principles are generally the first tools employed after a system has been diagrammed and the problems are well understood.

A technical contradiction arises when traditional science or engineering is used to improve one aspect of a system while reducing the desirability of another aspect. Eliminating contradictions innovatively means there will be no loss in performance or properties for an improvement in other properties. A classic example of a technical contradiction is when increases in strength of a material come coupled with increases in size and weigh. Resolving the contradiction would provide a strong, lightweight, compact material.

It is important to note the difference between innovative problems and design, engineering, or technical problems. Inventors solve problems by eliminating contradictions. Problems that lack physical or technical contradictions should be solved by designers, engineers, technicians, etc. using traditional engineering methods. It is the job of the designer, engineer, or technician to apply the innovative concept, found by the inventor, to a product, process, or system.

Any technical contradiction that could occur will be between any two of the set of 39 parameters (properties) that Altshuller has identified. Examples of these parameters are ‘weight’, ‘temperature’, ‘reliability’, ‘adaptability’, and ‘productivity’ [6]. Altshuller found that a contradiction between any two of the parameters was solved with an innovative solution. He also found that the methods used to acquire a solution to the contradictions were definable. Forty methods, called principles, were discovered within the patents that include methods such as ‘segmentation’ (dividing an object into parts), ‘use of mechanical vibration’, and ‘nesting’ (contain an object within another) [6]. A contradiction matrix was formed in which principles are listed that have commonly been used to solve the given contradiction.

At first, contradiction theory sounds as if it were the panacea of the innovative world. The fact is that the most difficult work comes before and after the theory is used. Figure 3-7 shows the process of identifying a problem and carrying that through the theory to a solution.

Figure 3-7: Process for Employing Contradiction Theory

When a contradiction is identified it is normally stated in technical terms, specific to the field where it came from. The technical terms must be translated into generic terms so that the parameters can be selected. Representing the contradiction in generic terms may require a broad definition of a parameter. The computer term baud rate (bits/second) would be translated as the parameter speed.

Once a principle has been identified it must be applied to the specific problem becoming a specific solution. None of the principles can be used alone to solve a difficult problem. A technique may have been identified but it must be applied in a way that improves on the original system. A great deal of thought, creativity, and experience is required during this stage.

Contradiction Theory is the basis of many of the other TRIZ tools some of which will be discussed in the next section.

3.3.5. Other TRIZ Tools

This section will give a brief overview of some TRIZ tools other than those already discussed. These tools, which are less used and generally more complex include: Substance – Field Analysis, ARIZ, and Patterns of Evolution.

Substance-Field (Su-Field) Analysis should be used in situations where a problem is well formulated. Every Su-Field Model will contain at least two substances and at least one field. The terms substances and fields are used very loosely. Output from the system originates from a substance that is acted upon by another substance. A field, or energy source, typically acts on both substances and causes the output. Substances can be simple building blocks or complex systems. Fields may range anywhere from gravitational forces to nuclear reactions. After a system has been modeled the designer can identify complete, incomplete, ineffective, and/or harmful components on which to concentrate. A typical Substance-Field diagram can be seen below in Figure 3-8.

Figure 3-8: Substance Field Model

ARIZ is the Russian acronym for Algorithm of Inventive Problem Solving. ARIZ uses the other TRIZ tools in combination to identify contradictions and model problems. ARIZ is only required for about 5% of all TRIZ practices because of its extreme level of detail (2). The first version of ARIZ only contained about five steps but over time as TRIZ theories were better understood it has evolved to a point now in which it is comprises approximately 100 steps.

One of Altshuller’s original discoveries was that designs evolved in the same way as other designs starting from conception and ending at death. Eight particular patterns were recognized and today are the part of TRIZ called Patterns of Technical Evolution. Patterns of Evolution should be used by an organization when they wish to gain a technological advantage over the competition. The eight patterns are as follows:

  1. Evolution in Stages: Technological design go through stages of pregnancy, birth, childhood, adolescence, maturity, and decline approaching death.

  2. Evolution Towards Increased Ideality

  3. Non-uniform Development of System Elements: Subsystems of designs do not evolve uniformly which results in contradictions.

  4. Evolution Towards Increased Dynamism and Controllability

  5. Cycles of Complexity and Simplification: Systems that have become simpler are combined, becoming a complex system, which is then again simplified.

  6. Evolution with Matching and Mismatching Components

  7. Evolution Toward Micro-level and Increased use of Fields

  8. Evolution Toward Decreased Human Involvement

3.3.6. TRIZ Application

TRIZ is a tool used to aid the engineer, designer, etc. in solving problems innovatively and creatively. Functional diagramming and Contradiction Theory were the two parts of TRIZ most applied to this project. The implementation of these tools in this project will be discussed here.

3.3.6.1. Functional Diagramming

Functional diagrams were used in this research as simple cause and effect graphs, showing the functional interactions between parts. Many gains can be reaped from functional diagrams. Three benefits were fully realized during this project. The first advantage is identifying harmful effects and their implications. Harmful effects in functional diagrams are often technical contradictions. The second advantage is obtaining opportunities for part removal, which is also called trimming. Lastly, after reviewing the problem in a graphical form, the entire system was comprehended more thoroughly.

The entire automatic boarding machine was split into four subsystems: ‘transfer’, ‘opening’, ‘loading’, and ‘board support’. Functional diagrams for these subsytems can be seen in the Appendix sections A.3 through A.6 respectively. The ‘transfer’ subsystem transports a loose, unoriented sock to the ‘opening’ subsystem. The ‘opening’ subsystem orients, opens, and places the sock in position to be loaded onto the board. The ‘loading’ subsystem places the sock on the board. The ‘board stabilizer’ subsystem accurately aligns the board with the loading assembly’s sock loading fingers.

Trimming is the process of examining the system and removing parts. Parts are “trimmed” by identifying other componentsor freely available resources that can supply the function of the part to be trimmed. Transferring the function of the part removes the necessity for that part. Ideality and trimming are closely related as one can see from Equation 3.1. Removing a part from a system will result in lower cost, which raises the Ideality of the system. The following is an application of trimming from this research. The change in Ideality of the system will also be shown.

Trimming Application 1

Rollers are used for conveyor belts that transfer the sock to the opening stage. Roller bearings are used to support and rotate the conveyor belt rollers. In the original design, the bearings are mounted in a housing that is attached to the frame by mounting screws. The housing tends to slip, (harmful effect), on the frame surface after time because of the vibration from rotation of the bearing and rod. Figure 3-9 shows the solid model of the bearing-roller subsystem. Figure 3-10 shows the functional diagrams of the subsystem before and after trimming.

Figure 3-9: Roller-bearing Solid Model

Figure 3-10: Roller-bearing Functional Diagrams

This assembly was examined for components that could be removed to improve the Ideality. It was identified that the frame could supply the function of the bearing housing and the button cap screws by acting as the stabilizer and mount. The harmful action of the bearing housing slipping on the frame will also be removed because the bearing will be constrained by the frame. Figures 3-10 and 3-11 show the solid model and functional diagram after trimming.

Figure 3-11: Roller Bearing Solid Model after Trimming

Removing a harmful function and lowering cost will result in increased Ideality as can be seen in equation 3.1. The screws and bearing housing were removed as a result of the trimming applied as well as the harmful effect of the housing slipping. No useful function was lost as a result of trimming the parts. The total savings in parts cost was approximately $6 per roller bearing assembly. A total of fourteen roller bearing assemblies will result in $84 savings.

Trimming Application 2

The ‘board stabilizer’ subsystem accurately aligns the board with the loading assembly. Vertical alignment of straight boards produces the correct positioning of the top of the board with the sock loading fingers. The board stabilizer mechanism can be seen below in Figure 3-12 and read about in greater detail in section 4.2.4.

Figure 3-12: Board Stabilizer Trimming Example

The number of parts used in this assembly was far too large for the purpose it served. The functionality of the stabilizer was also deemed insufficient because boards that were bent above the stabilizing assembly would not be aligned properly. The stabilizer mechanism has no effect on the board above the assembly. This fact is compounded for taller boards. Figure 3-13 is a functional diagram of the board stabilizer showing how many components are used to simply align the board.

Figure 3-13: Board Stabilizer Functional Diagram

There are many places where one could begin trimming parts from this assembly. Rollers will continue to be used as the aligning system because of their ease of use, low cost, and availability. Using only one rolling mechanism on each side of the assembly instead of using the current two bearings will remove two parts. Using a longer roller will have the same effect as using two bearings that are separated. The remaining components are only used to support the bearings.

One can see from the functional diagram the complexity of the bearing support structure. Six parts are used to support two bearings on each side of the board. Keeping the ideal system, (3.1), in mind, which would use no parts to align the board, the functional diagram is examined. By examining the functional diagram we can see that all of the support component’s functions can be replaced by one component. Using one roller and only one part to support that roller would be much closer to the ideal system in comparison to the current design. The total number of parts would be reduced from 16 to only 4. The only loss making this change is in flexibility. The current assembly could adjust around the board to compensate for changes in the design of the rest of the AutoLoader. However this flexibility will not be required or necessary in a manufacturing setting.

Components used in the previous assembly were expensive because they were specialized and custom made. Irregular sizes and number of holes and slots increased the time to make them. Total cost of the assembly was approximately $310 if the bearings cost $10 each, slides and connectors cost $30 each, and the support blocks totaled $30. Plastic Rollers could replace the bearings, which would only cost approximately $10. Half-inch diameter steel rod can be used to support the rollers. The roller can be held in place on the rod by using two clevis pins, which only cost a few dollars. One end of the rod would be threaded so that it can be mounted on the Intech by using a nut on each side of the Intech frame. The plastic rollers, rods, clevis pins, and small amount of machining to the rod would result in a total assembly cost of approximately $70, resulting in a $240 savings.

Removal of twelve components enforces the TRIZ tool: Patterns of Design Evolution. The fifth pattern states that technological systems evolve from complexity and then back to simplification [6]. The fourth pattern states that systems will also evolve toward increased dynamism and controllability. In an effort to increase the control over tall boards, the placement of the rollers on the mount could adjustable. Depending on the length of the sock being boarded one could move the rollers higher on the board for greater control and less movement of the assembly. A functional diagram and solid model of the new board stabilizer assembly can be seen in Figures 3-15 and 3-16 respectively.

Figure 3-15: New Board Stabilizer Assembly Functional Diagram

Figure 3-16: New Board Stabilizer Assembly Solid Model

3.3.6.2. Contradiction Theory Application

Contradiction theory is generally used when the designer wishes to increase one parameter of a design without negatively effecting another parameter. The most common example of this may be increasing strength without the technical tradeoff of increasing weight. The main benefit of contradiction theory to this design has been idea generation. Reviewing the forty principles is a more systematic approach to idea generation than a conventional brainstorming session. The difference in using contradiction theory is that general solutions are given for general problems. General solutions must be transformed into applicable designs. Two applications of contradiction theory are given below.

Contradiction Theory Application 1

Socks exit the sandwiching conveyor belts when the sock reaches the top of the machine. Socks then follow the bottom belt until it reaches the opening area. Problems occur when the sock follows the top conveyor instead of the bottom. Friction of the sock with the top conveyor belt causes fibers to get caught which pulls the sock with the belt. Originally a metal plate was used to separate the sock from the top belt. This function was insufficient, because it often jammed the sock. The metal plate also caused sock abrasion, which is a harmful effect. A solid model and functional diagram of the process where the sock exits the conveyor belt can be seen below in Figures 3-17 and 3-18. The insufficient separation action and harmful abrasion action are shown to be a dotted line and red line, respectively in the functional diagram.

Figure 3-17: Original Conveyor Belt Exit Solid Model

Figure 3-18: Original Conveyor Belt Exit Functional Diagram

The specific problem of the sock getting caught on the top conveyor belt must be worded into a general problem. The two parameters chosen that best fit the problem were ‘reliability’ and ‘complexity of device’. It was desired to increase the reliability of the device without the engineering tradeoff of increasing its complexity. There were three principles suggested in the contradiction matrix to solve this problem but none of them appeared to apply in this case. The principle ‘use a hydraulic or pneumatic construction’ appeared to have a possible application. Instead of using a solid piece of metal to separate the sock and the conveyor belt, an air nozzle with a thin air profile could be used. The nozzle would create an “air knife” that would flow along the surface of the top belt and thus would peel the sock away. The air knife could not have the harmful effect of jamming the sock because there is nothing physical to create a pinch point. A solid model of the air nozzle separating the sock from the belt can be in Figure 3-19.

Figure 3-19: “Air-Knife” Application

The resulting functional diagram using the “air-knife” may be seen in Figure 3-20. The insufficient action and harmful action have been removed. The cost of the air nozzle and its mount is slightly higher than using the metal plate alone. Therefore the Ideality of the machine will improve but only to a small extent because of the off setting effect of the additional cost of the air nozzle.

Figure 3-20: Conveyor Belt Exit Functional Diagram using the “air-knife”

Contradiction Theory Application 2

The second application of contradiction theory has not yet been implemented but is an excellent example. When socks are loaded they must be widened to the largest width of the board, which is around the heel. Certain socks are damaged when they are stretched to this point. The specific problem is how to prevent the sock damage while maintaining the ability to pull the sock over the heel of the board. The general contradiction using TRIZ parameters is how to change the ‘shape’ of the sock without causing any ‘harmful side effects’. The following paragraph gives a brief description of the loading process.

Socks are loaded onto the boards using metal ‘fingers’ that slip into the open end of the sock. There are four fingers altogether two of which are inside the sock while the other two grip the sock from the outside. These metal ‘fingers’ work similarly to a human finger and thumb. Each inside/outside finger pair of is attached to a pneumatic clamp. Once the sock has been placed over the fingers by the ‘opening’ subassembly the sock is widened by a horizontal pneumatic slide that one of the clamps is mounted to. The sock is then pulled over the board. This process can be read in more detail in section 4.2 Mechanical Design. A solid model of the sock being held by the fingers and widened by the pneumatic slide can be seen below in Figures 3-21. The functional diagram, Figure 3-22, shows the harmful effect of stretching the sock caused by the horizontal pneumatic.

Figure 3-21: Sock Widening Solid Model

Figure 3-22: Sock Expansion Functional Diagram

The loading ‘fingers’ were determined as a possible area to reduce the sock damage occurring due to widening the sock. The TRIZ principle ‘dynamicity’ was selected to resolve the general problem of how to change the ‘shape’ of the sock without causing any ‘harmful side effects’. The definition of dynamicity is “make characteristics of an object or outside environment automatically adjust for optimal performance at each stage of operation.” [6]. This principle must now be applied to the problem using specific terms.

Socks only need to be at the widest point for a moment, when they move over the heel area. The rest of the time they can be stretched much less. Just as when one is putting a sock on their foot. If the sock were heel width for only a moment, when required, minimal damage would occur. The definition of dynamicity may be interpreted as: “make immovable objects, movable”. The loading ‘fingers’ currently utilized are made of aluminum. If the ‘fingers’ were made of a different substance that was flexible, they would flex in when the board is more narrow and flex out when the board is wider such as around the heel. A solid model of the flexing clamps can be seen below in Figure 3-23.

Figure 3-23: Flexing Clamps Solid Model

The principle of ‘segmentation’ was also used to generate solutions. The definition of segmentation is “divide an object into independent parts or make an object sectional”. These definitions spawned the idea of separating the clamps into two sections. One section was stationary and the other section was connected to the stationary part. The second part could move according to the sock width. This idea has the same purpose as the first, allow the sock to be wide only when necessary. The first solution would be closer to the ideal because it requires fewer parts.

REFERENCES

  1. D.C. Alexander, B.M. Pulat, “Industrial Ergonomics, A Practitioner’s Guide”,
    Industrial Engineering and Management Press, Norcross, GA, 1985

  2. George Lucas, Tim Clapp, “Hosiery Consortium Benchmark Report: Cost and Quality”, 1998

  3. “Preserving Hosiery Manufacturing in North Carolina, Strategies for Modernization Through Technologies”

  4. David G. Ullman, “The Mechanical Design Process”, McGraw-Hill, New York, NY, 1997

  5. John Terninko, “Step by Step QFD: Customer Driven Product Design”, Responsible Management Inc., Nottingham, NH, 1995

John Terninko, Alla Zusman, Boris Zlotin, “Step by Step TRIZ: Creating Innovative Solution Concepts”, Responsible Management Inc., Nottingham NH, 1996