Duct Pinner 5000

ME 493 Final Report - Year 2016

Portland State University

Michael Thilavanh, Osten Palmrose, Chase Doyel,

Clint Everett, Sheng Chen, Haoyuan Xu

Academic Advisor: Robert Paxton

Project Sponsor: Mark Van Sickle

Executive summary

Streimer Sheet Metal Works Inc. is full-service sheet metal contracting and fabrication company with extensive experience in air duct manufacturing. Streimer is seeking to improve their process for fastening sheets of fiberglass insulation to air duct sheet metal. Streimer has selected three main targets for the final design which includes an increase in safety, efficiency improvement of 20%, and ease of maintenance.

Original target and deliverables for the project was for the completion of the machine by June of 2016. However, with research and design requiring more time than initially thought, the deadline would have to be extended. During February, the group met with project sponsor representative Mark Van Sickle to discuss new possible project targets. Following discussion and approval from our sponsor, the Product Design Specification (PDS) requirements changed from design and manufacturing of the machine to having a detail design, detail Bill of Materials, assembly drawings, operation flow chart, and detailed CAD model.

Working towards the final design Finite Element Analysis (FEA) was used to conduct evaluation of the strength and natural frequency of the frame The frequency was import to evaluate due to vibration interference with the hopper bowls, and the frequency of the impacts to the sheet metal.

After the final concept design of the Duct Piner 5000, further validation is recommended during the assembly process. Actuator movement, Programmable Logic Controllers (PLC) coding and dynamic response of the machine should be validated for meeting the target goals.

Table of Contents

Introduction and Background Information………………..………………………………………3

Mission Statement…………………………………………………………………………………3

Main Design Requirements……………………………..…………………………………………4

Top-Level Alternative Conceptual Solutions……………………..………………………………4

Final Design………………………………………………….……………………………………8

Results of Various Evaluations…………………….………….…………………………………15

Conclusions and Recommendations………………………………..……………………………16

Appendices……………………….………………………………………………………………19

Introduction and Background Information

Streimer Sheet Metal Works Inc. is a family owned company based in Portland, Oregon specializing in air duct manufacturing and assembly. The company started after World War II in 1946. Streimer can fabricate unique air duct assemblies to accommodate any specific air delivery needs. Having many years of experience and knowledge regarding air duct manufacturing, Streimer is interested in improving one of their current manufacturing processes.

One of the manufacturing processes Streimer would like to improve on is the joining of insulating material to the air ducts. Prior to the sheet metal being formed into a fully enclosed air duct, fiberglass insulation is joined to the sheet metal via adhesives and fastening pins. First the adhesive is applied to the sheet metal, and fastening pins are resistance welded to hold the insulation in place as the adhesive cures. Current tooling of the resistance pin welding is being examined for any possible areas of improvement. Working alongside engineering students at Portland State University, Streimer hopes to find a solution to improve their methods.

Streimer is aiming to achieve an efficiency increase of 20%, and develop a low maintenance, reliable machine. The group of students will evaluate the current methods, research different technologies to improve existing methods, and explore the development of new tooling. Some of the challenges faced by the team include meeting deadlines from concept to final product, complying with the Sheet Metal and Air Conditioning Contractors’ National Association (SMACNA) standards, and being able to satisfy Streimer’s critical needs, such as accommodating various duct geometries with improved equipment.

Mission Statement

Our mission is to work alongside Streimer Sheet Metal Works Inc. to satisfy their goals of increasing efficiency and reducing maintenance needs, all while holding safety to the highest standard. We will evaluate existing processes to determine what will best help Streimer meet their targets. Through careful planning and execution the team will use the resources provided by Streimer to reach their targets to the best of our ability. We will create, discuss, and compare our design ideas in order to reach a consensus of what our final design will be.

Main Design Requirements

The main objective for the project is to increase the efficiency of attaching the pins to sheet metal by a minimum of 20%. Primarily focused on cycle times. The machine must be able to accommodate a variety of different sizes and shapes of sheet metal panels while being able to accommodate variable spacing between the attachment points. At the same time the machine must be able to comply with Sheet Metal & Air Conditioning Contractors’ National Association (SMACNA) HVAC construction standards.

Some secondary design requirements that the Streimer would like to see are improved safety for the workers. The machine also requires low maintenance, improved ergonomics based on the existing model, and attaching pins to have a success rate of over 95%. Additional design requirements is attached in Appendix E. With these primary and secondary design requirements our group is set to design a machine that will meet or exceed these requirements with the proposed budget of $10,000.

Top-Level Alternative Conceptual Solutions

Early in the project's design process, a design matrix was created by comparing three initial concepts. The design matrix used to compare our conceptual designs to various design requirements, this is shown in Table 1. A design matrix gives us a better understanding of possible components to include in our machine as well as allowing us to narrow our focus on more crucial aspects of the machine.

Individual Designs

Accordion Head

Single Head

New Design

Group Member

Osten

Michael

Chase

Budget

Medium

Medium-High

Medium-High

Manufacturability

Medium-High

Low-Medium

Medium

Automation

Low

High

High

Scope

Medium-High

High

Medium-High

Joining

TBD

TBD

TBD

Selection Points

10

13

15

Table1: Decision Matrix Used to Evaluate Three Possible Methods

After analyzing the results of the design matrix, we discussed what aspects to include in the revised design. A collaborative design was then created with the specifics as follows:

1. Four pneumatic actuators, three of which controlled by linear stepper motors.

-Productivity are quadrupled for large sheets. The actuators controlled by the motors will be able to accommodate for the various sizes of sheet metal.

2. Four Gripnail hoppers to feed each punch point.

-Off the shelf design allows for easy integration onto our machine design.

3. Adjustable sheet metal support grid.

-Ability to punch different size sheets, dual or quadruple flanged with ease.

4. Control panel adjustment of the three actuators.

-Ability to punch a variety of sheet sizes with ease.

5. Laser point accuracy on each pin punch.

-Improves operator precision knowing exactly where each pin will punch.

Once a new design was agreed upon, it was then compared to Streimer’s current machine. This second design matrix, shown in Table 2 was created due to the observation that the new design was similar to the current machine as well as the possibility of modifying Streimer’s machine to create a more efficient machine for a lower cost.

Table 2: Rating Matrix Used to Evaluate Each Criteria

The results from the final design matrix show that the new design would be a slightly more viable option. Since the score was close, we asked Streimer to make the final call, they acknowledged our findings and encouraged us to go with the new design. After this decision, we assigned main components of the machine to each member of the team. These components are: frame, frame impact surface, actuators, actuator positioning, and controls. Out of these components, the actuator and frame were analysed and tested thoroughly. The actuators in the new design needed to be able to physically drive a gripnail into sheet metal unlike Streimers machine which uses weld pins to attach the sheet metal insulation. To find the amount of impact needed to drive the gripnail into the sheet metal a mass was dropped from varying heights onto the head of the gripnail. A piece of PVC pipe fixed to the leg of a table was used to guide the five pound brass rod as it dropped. A sheet of paper was marked every inch and used to indicate drop height. A half inch plate of steel was used as the impact base. The pins were placed directly on the sheet metal and held in position using a soft sponge. Starting from the lowest distance, the brass rod was dropped from increasing heights up to 25 inches. Below, Figure 1 is the resulting graphical representation of the influence of impact on pin position.

Figure 1: Graph of Influence of Impact on Pin Position

In addition to these tests, tensile tests were carried out to identify the ideal required impact force of the actuator; also to compare the relative strength of the Weld pins and Gripnails, as well as verify the previous experiment. Gripnails that were firmly impacted into the sheet metal in the previous experiment were also used in the tensile tests to correlate the extraction force with the amount of impact, Figure 1 shows this graphical correlation.

To tensile test the pins, a custom tool was machined by one the members of our team. The design was made to fit into Portland State University’s pre-existing tensile testing machine while also securing the pin in a way that would minimize the deflection of the top of the pin and provide a maximum surface relation with the pin. The force required to punch each pin was then determined using this data, and is shown below in Figure 3.

Figure 2: Graph of Extraction Stress Strain Curves

Figure 3: Impact Kinetic Energy to Gripnail Versus Required Extraction Force

The results of the tensile tests showed a plateau of the extraction force, representing an important trend of the ideal impact range for the longest lasting grip from a gripnail. The results of this test determined the optimal impact kinetic energy for ensuring the strongest bond of the gripnail to the sheet metal. From the data, the ideal kinetic energy required to punch a pin was found to be between 6 and 9 ft-lb of force. After this test an actuator that fit the data and criteria was chosen. To accommodate the actuators and counteract their generated impact force the frame was subjected to various design alterations and finite element analysis. These alterations take into account the distance for impact and the weight of attached components. A cantilever beam, as a simplified representation, was generated in a finite element program. The program simulates loading conditions and provides feedback of areas of deflection and stress. This program also helped in determining which frame design would have the longest life and rigidity. A convergence study was done on all frame designs to generate acceptable results. Each design was simplified into a 2D beam and a pressure force of 500 lbs was applied to the top of the cantilever beam. Once a potential ideal design was chosen, it was subjected to modal vibration analysis. The natural frequency of the structure was determined, which was compared with the bowl feeder potential operating frequency to ensure interference would not occur. A two post cantilever beam design was implemented into the final design to support the weight of the combined rail guidance system and impact mechanism. This design will be able to withstand more torque, vibration, and weight compared to a single post cantilever beam as well as the other generated designs.

Final Design

In an attempt to address all design metrics, the Duct Pinner 5000 was born, and can be seen below in Figures 4 and 5. This machine has the ability to drastically improve efficiency by punching four Gripnail pins in at once, with laser point accuracy.

Figure 4: Duct Pinner 5000 Final Design

Figure 5: Duct Pinner 5000 Final Design

Frame:

The frame design was very important because of the amount of force this machine is capable of generating. The frame is shown below in Figure 6 and features a combination of 4x4x0.25” square tubing, and a S5x10 steel I-beam.

Figure 6: High Strength, Impact Resistant Steel Frame

The web of the I-beam is able to resist the shear forces, while the flanges are able to resist the bending moment experienced by the 265 lb cantilever beam. To eliminate any harmonic vibration the machine may experience, all major supports are gusseted for stiffness.

Impact Mechanism:

The impact mechanism needed to be powerful, and reliable to eliminate any machine down time. Each pin is self fed down a track into position. A small actuator loads each pin into position under the punching head. The pin is held in place by a high strength magnet. The 411 lb capable, impact resistant actuators, are turned down to around 20%. The optimum force required to punch a pin is around 80 lbs using our Gripnail punch. Lightly using a heavy duty component ensures a high factor of safety on the mechanical components, and a long service life. This mechanism is shown below in Figure 7.

Figure 7: Self-Feeding Pneumatic Gripnail Punch

Gripnail Hopper:

The hopper bowl vibrates flipping Gripnail pins upside down. The pins then vibrate around the outside of the bowl, eventually reaching the top and falling into the pin track. This system is automatic and can reliably feed 30 pins per minute. Shown in Figure 8 below. The pins can be easily reloaded into the hopper at any time.

Figure 8: Self-Feeding Pin Hopper

Linear Motor:

The three rear hoppers are each controlled quickly and easily by non-captive programmable linear motors on an ACME screw as shown in Figure 9. The motors and actuators are supported by pillow blocks on a two guide rail system which was designed to dampen the torque generated by the actuators and accurately align the impact mechanism. Due to the dissimilarity of sheets needing pins, this gives the operator the ability to adjust the position of each actuator prior to pin engagement. The operator is able to make adjustments from the machine control panel.

Figure 9: Linear Motor Control of Aft Three Actuators

Control Panel:

The control panel shown in Figure 10, allows the operator to accurately position the rear three actuators. The operator can use the digital readout of exact actuator position, or simply adjust using the laser point as a guide.

Figure 10: Control Panel

Machine Controls:

The entire system is controlled by a Programmable Logic Controller (PLC). The PLC monitors each linear motor position to avoid any component collisions. The PLC also keeps each Gripnail punch loaded and ready for use. Eight pneumatic solenoids run the operations of the system, this is shown further in Figure 11.

Figure 11: Pneumatic and Electrical Enclosure

Procedure:

The process for using this machine is as follows: an insulation sheet will slide onto the table and be positioned in a datum point. The operator will then adjust each applicable actuator position either using the digital readout of exact position, or by visual examination of the laser point, any actuators out of range of the work piece would be disabled. Once in position, the operator will depress the foot pedal punching Gripnails through the insulation into the sheet metal. Next, the operator will reposition the sheet metal, and repeat the punch on the opposite side of the sheet. For larger sheets the operator would also punch the middle of the sheet. Once completed, the operator will slide the sheet off the left side of the machine and move onto a new piece. If the following sheet has the same dimensions, the operator could quickly repeat the punch with the same settings until an adjustment is required. The entire process would take less than two seconds to complete.

This set up is ideal for large quantities of the same geometry. The process is much more productive than the current method of welding each pin individually.

Results of Various Evaluations

Performance and Functionality:

Streimer’s existing PowerPinner welder is considered a relatively slow performing machine in that it spot weld’s a pin with about a two to three second cycle time. The focal point for design work going forward involved improving the speed of performance by at least 20%. The Duct Pinner 5000 was designed with four heads targeting an immediate speed improvement of as much as four times depending on workpiece size. Fastening of the gripnail over the weld pin is expected to be faster on an individual cycle basis by eliminating the time required for welding.

Ease of use was an important consideration going into development of the input interface and usability layout of the Duct Pinner. Moving the input panel from below the operator’s waist on the current machine to eye level places the important active actuators and position information in a better location for frequent use. The interface is simple yet capable enough to fully control the Duct Pinner’s key features. The flow of workpieces through the machine was kept similar allowing them to be moved from left to right. Effort was also placed into limiting the amount of handling required for each workpiece by creating an surface for it to rest on and lasers to guide actuator positioning. One opportunity for continued improvement to the user interface would involve implementing a graphics terminal in place of the input panel to allow for manual specification of workpiece dimensions. From here, through programming, the actuators could be automatically be positioned to fit the workpiece size.

Structural Integrity of Design:

The Duct Pinner is subjected to different forces than a PowerPinner welder; causing for a need to pay heavy attention to the redesigned machine structure. With actuators that provide an impact, greater kinetic forces are distributed throughout the machine than with the welding motion. Finite Element Analysis (FEA) was used to support the design of the cantilever component of the frame and its supports. The L-shaped cantilever supports the loading and energy associated with impact actuators and helps ensure the footprint of the machine is minimized. Square tubing welded to form the work surface and frame ensures strong structural properties.

Manufacturability and Assembly:

In part assisted by the simplicity of the frame’s design, through use of square tubing and and an I-beam, fabrication of the frame will not be complex. This is important because much of the machine will be fabricated by Streimer using in-house materials and tools. Sheet metal enclosures were used where possible like on the solenoid panel and side panels, these can be fabricated in house. Electronic components and the mechanical components of the cantilever arm will provide the most complexity in assembly. However, code within the PLC is where the heart of the Duct Pinner’s features are implemented, and this will likely present the greatest challenge when preparing the machine for use.

Cost and financial performance:

Considering the initial budget provided of $10,000, the Bill of Materials shows that components will cost slightly more in total. However, considering the cost of other PowerPinners and Gripnailers available on the market the Duct Pinner 5000 is priced to provide more features for a lesser cost.

Conclusions and Recommendations

Once the target goals were determined, many potential design possibilities were considered and an initial design was drafted. All the efforts put towards the Duct Pinner 5000 thus far has been towards defining the first concept of the machine. The next leap in the design process of the Duct Pinner 5000 would be the proof of concept stage. In the next phase, many of the concepts drafted need to be validated in order to reach the original targets.

A key feature in the new machine is the method of fastening the nail to the sheet metal. It is believed that the grip nails will be able to reach the speed, reliability goals, as well as be at a cost advantage over the alternative. Experiments show the minimum, maximum force, and energy needed to apply the nail to the sheet, but in the next phase the parts specified in the Bill of Materials should be validated if they meet the impact and speed criteria.

Actuator movement is the next aspect of the design that should be closely considered during the validation process; the drafted design will have a strong impact on speed, ease of use and reliability. Four heads were introduced compared to the single head in the current machine and it is key that these four heads can be properly utilized quickly to justify the new design. From the Bill of Materials the components selected to move the actuators such as lead screw, motors, supports, and all the necessary electronics need to provide not only the fastest speed but precise movement as well. Actuator movement is a very detailed section to the design and the validation can become time consuming and expensive if not approached properly.

Dynamic responses of the machine need to be determined because many uncertainties can arise in machine operation if the response unknown. One of the primary sources of vibration will be coming from the feeding bowl. The operation frequency is known but further testing will need to be done to determine if any interference will come with the multiple bowls. The interference has the potential to be constructive or destructive. Impact of the nails to the sheet metal will be the second source of potential resonance. From F.E.A. modeling the resonate frequency of the structure was determined and the impact frequency of the cantilever and actuators should operate above this frequency.

The frame of the machine should be one of the last components ordered and fabricated for the tool. Once the impact mechanics and actuator movement has been validated, the structural strength of the frame needs to be validated. From the initial F.E.A. modeling the deflections shown were at an acceptable level, but the design needs to be validated so that the structure will not deflect and deform to unacceptable levels. Additionally, the impact surface needs to be validated for impact hardness and longevity.

During the purchasing of the components it is recommended that certain components be ordered before others. All the components for the impact mechanics should be purchased first. This includes the air cylinders, impact head, and feeding system. Once a single head has been shown to work properly the additional heads should then be purchased. Next the components to move the actuators should be purchased. It must be shown that the actuators can move properly before buying the framing components. As the Bill of Materials currently stands the projected cost is over budget by 5%. Sourcing the components locally may drive down cost staying within budget. Finally many components to this machine will have to be fabricated, determining which parts can be machined in house and which have to be sent out of house will greatly affect the cost of the project.

Appendices

Appendix A: Production Drawings

Drawings showing general dimensions and layout of the Duct Pinner 5000.

Figure A1: Duct Pinner 5000 General Dimensions

Figure A2: Assembly Layout

Appendix B: Bill of Materials

Categorized bill of materials showing estimated cost for each feature.

Category

Total

Frame Assembly

$2618.06

Solenoid Panel

$1518.07

Input Panel

$387.90

Feeding System

$2330.32

Actuator Mechanism

$1764.74

Actuator Guide Rail System

$1098.78

Impact Surface

$667.9

Fastener

$261.82

Electronics

$57.77

Total

$10493.52

Figure B1: Bill of Materials Sorted by Section

Appendix C: Operation Manual & Safety Warning

There are 4 basic steps to use Duct Pinner 5000

Preparation: turn on machine and fill each feeding bowl with Gripnails.

· First, adjust the position of each actuator head and select the number of heads you want to use into the input panel.

· Secondly, put the sheet metal on the raised impact surface. Using lasers to guide the material into right position.

· Thirdly, when the sheet metal is properly aligned, step on the foot panel to punch the Gripnails onto the sheet metal and then move sheet medal for next punch.

· Finally, when finished, repeat steps one to three for new pieces of sheet metal.

In case of emergency, the machine can be stopped by pushing the emergency stop button.

During operating the machine there are some basically rules.

· Do not put you hand under actuators while machine is running.

· Do not manually change the position of the actuators, the position can be controlled by input panel.

Appendix D: Experiment, Analysis and Evaluation:

Strength testing was performed using a tensile tester to determine the joining strength of weld pins and gripnails, and to determine material strength for a common gauge of sheet metal used at Streimer. Results showed showed the weld pins bonding five time stronger than gripnails with an ultimate strength of 19.57 Kpsi. Despite this, gripnails had a high strength value 4.10 Kpsi before the joints failed. Tensile testing of the sheet metal specimen showed an ultimate strength at 29.87 Kpsi. These results were important going forward because they show that a Gripnail-to-sheet metal joint will be the first thing to fail in insulated ducting.

Knowing that gripnail joints failed first, impact testing was performed to determine the optimum impact energy for fastening. Various impact energies were tested, and then the nails were extracted with the tensile tester to determine the joint strength. An ideal impact range from 6.25 ft-lb up to 8.75 ft-lb of impact kinetic energy was determined to work best. These findings were used to design the impact actuator mass and assembly.

Appendix E: Internal and External Research:

Working through internal options, Streimer uses both gripnails and weld pins in their current process. Weld pins are used in the PowerPinner machine. The machine itself has several valuable features that are not utilized in day to day operation, and as a result several ideas arose out of these opportunities. For one, the current PowerPinner could benefit from repair. However, Streimer’s desire was for a machine that could significantly out-perform the old, and repairs to the old machine would not provide the desired improvements. Knowing that a new machine would need to be designed the choice of fastener became the next important consideration.

DuroDyne and Gripnail are industry leaders in duct insulation fasteners providing a combination of adhesives, mechanical fasteners, and welding fasteners. Streimer is a customer of Gripnail and recommended use of the Gripnail mechanical fastener over a welded fastener. Both manufacturers provide machines that served as inspiration. For mechanical fasteners there are solutions which impact individual nails into sheet metal, and Gripnail has an older model with two heads. For larger scale processes there are welded fastener machines that secure five nails at once across a large sheet, however, no solution exists for mechanical fasteners. Components of each of these products served as inspiration for the Duct Pinner 5000.

Appendix F: Project Plan:

Appendix highlights important tasks and their expected timelines for start and completion.

Project Plan

Tasks

Start Date

End Date

External Search

1/12/2016

1/28/2016

Internal Search

1/12/2016

1/28/2016

Concept Brainstorming

1/12/2016

1/28/2016

Project Method Proposals

1/19/2016

1/28/2016

Concept Selection and Evaluation

1/12/2016

1/28/2016

Progress Report Presentation

1/12/2016

2/2/2016

Detailed Design

1/28/2016

2/2/2016

Sponsor Meeting and Review Design

2/2/2016

2/22/2016

End of Term Progress Report

2/1/2016

3/8/2016

Prototype

2/15/2016

3/13/2016

Testing

2/15/2016

3/13/2016

Redesign and Modifications

2/15/2016

5/16/2016

Prototype Improvement and Further Testing

2/15/2016

5/23/2016

Documentation

1/12/2016/

6/6/2016

Manufacture Final Product

5/23/2016

6/6/2016

Table F: Project Expected Timeline

Appendix G: Priority and Requirement Verification:

Contains requirements of final design and methods for verifying their completion.

High Priority Items

Requirement

Customer

Metric

Targets

Target Basis

Verification

Performance

95% reliability in fastener placement

Streimer

Percentage of fasters needing replacement

95%

Customer feedback

Test

Improve fastener application speed by 20%

Streimer

Fittings per day

20%

Customer feedback

Test

Accommodate sheet metal as small as 2x2 feet and as large as 5x6 feet

Streimer

Area measurement (Square feet)

Yes

Customer feedback

Test

Fasten insulation sizes ranging from 1-2 inches

Streimer

Inches

1-2

Customer feedback

Test

Regulations

Design complies with SMACNA standards

Streimer

Pass/Fail

Yes

Customer feedback

Test

Safety

Minimal risk of operator injury

Streimer

Pass/Fail

Yes

Team decision

Comparison

Timelines and Commitments

Meet all capstone deadlines

PSU

Pass/Fail

Yes

Team decision

Submission and completion dates

Ensure Streimer is informed and involved

Streimer

Pass/Fail

Yes

Customer feedback

N/A

Medium Priority Items

Requirement

Customer

Metric

Targets

Target Basis

Verification

Remain within Budget

Remain within $10,000 budget

Streimer

U.S. Dollars

Yes

Customer feedback

U.S. Dollars

Maintenance

Require equivalent maintenance

Streimer

Pass/Fail

Occasional

Team decision

Comparison to existing solution

Documentation

PDS report,

Progress report

PSU

Pass/Fail

Submit in timely manner with high quality

Team decision

Date submitted and grade earned

Low Priority Items

Requirement

Customer

Metric

Targets

Target Basis

Verification

Installation and Spacing

Minimize installation time

Streimer

Time

<1 hour

Team decision

Time installation process

Minimize required footprint of final product

Streimer

Square feet

Yes

Team decision

Comparison

Table G: Priority and Requirement Verification Table

Appendix H: PDS Report