P16602: Glass Cutting Machine Wire Supply, Movement and Takeup
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Week 8 Design Review

Table of Contents

Team Vision for Week 8 Design Review

Our vision for week 8 was to:

Our vision for this review:

BOM Update and Design Completion Percentage

For the majority of our components, we are at the RIT approval point, seeking guidance from Hanzlik and the machine shop. After meeting with the guys in the machine shop, designs have been updated to meet manufacturability and commercial grade standards. However, there are still a couple major design areas that require review. The entire traversing pulley system still needs to be designed. The frame is almost complete, but integration with full assembly as well as fixture assembly need to be considered. The flexible coupling for the spools and the control cabinet still require specification.
Key BOM Items

Live Revision of the BOM can be found here.

Dancer System Assembly

Dancer Pulley System

Dancer Pulley System

Bracket #1

Bracket #1

Bracket #1

Bracket #1

Bracket #2

Bracket #2

Bracket #2

Bracket #2

Bracket #2

Bracket #2

Supply Spool Purchasing

Supply Spool Proposal

ME Shop Conversation and Changes Update

Fixture Frame Design

Supply Side Frame Assembly

Supply Side Frame Assembly

Take-Up Side Frame Assembly

Take-Up Side Frame Assembly

CHANGES

Spool Subsystem Design

Take-up Spool

Exploded View of Take-Up Spool Assembly

Exploded View of Take-Up Spool Assembly

Locating Cones

Take-Up Cone Assembly

Take-Up Cone Assembly

Take-Up Cone Assembly Exploded View

Take-Up Cone Assembly Exploded View

Supply Cone Assembly

Supply Cone Assembly

Supply Cone Assembly Exploded View

Supply Cone Assembly Exploded View

The design for the guide pulley system has remained the same as seen in the week 5 design review. All components are designed for reuse on the final machine. Integration with full assembly has been considered. Final engineering vibration and structural tests are being looked at before seeking approval from the machine shop.

Guide pulley system

Guide pulley system

Guide pulley system clamp

Guide pulley system clamp

Guide pulley system bracket

Guide pulley system bracket

Guide pulley system bracket flattened

Guide pulley system bracket flattened

Controls

Traversing Pulley

The speed for the traversing pulley is a function of the radius, wire-laying angle and wire speed. In simple terms, it can be thought of as the distance per wrap over the time of one revolution. However, as the spool radius decreases, the angular velocity increases; as such, the time per revolution will decrease.

By looking at the geometry of the spool, we can determine that the distance per wrap, x, is related to the spool diameter and wire-laying angle.

With this information, we can solve for the traversing speed, T. We can vary the wire-laying angle or the distance traveled per wrap.

We decided to ideally bound the wire laying angle to be between 85 and 89.98 degrees (laying wire right next to itself at max radius for takeup spool). This results in the following extreme cases for the takeup spool.

Takeup Spool

Max Velocity = 1.0025 m/s

Min Velocity = 0.00253 m/s

Dancer Pulley and Spool Motors

The dancer system can be thought of like a flow issue - you have a certain amount of wire coming into the system, and a certain amount coming out. The dancer will accommodate for the velocity mismatch by changing the path length. If we define vm to be the wire velocity from the motor, vp to be the wire velocity on the guide pulley (and presumably the guide rollers), we can define the change in the path length to be the difference between these two multiplied by the change in time. By convention, extension will be defined as positive displacement. Assuming we can decouple from the traversing pulley system and look only at the dancer system, we can see that the extra path length would be split half and half in the 180 degree wrap, such that the change in path length is equal to twice the dancer extension, X.

Taking the derivative with respect to time, we find:

public/Wk 8 Review/dancer eq.PNG

As such, we can find out the exact tangential velocity mismatch between the rollers and the spools if we can measure the dancer velocity. Using a position sensor with a known polling rate, we should be able to accomplish this. Thus, we have the following:

Using the relationship defined above, we can plug in radius*angular velocity for the wire velocities, and solve for the instantaneous radius of the spool, R.

public/Wk 8 Review/radius eq.PNG

This gives us several possible control options:

Possible Control Options

  1. Motor Reference
    • Change the instantaneous value of the reference signal (angular velocity) to reflect the instantaneous radius
    • Pros: Better-defined relationship between motor and reference
    • Cons: Processing overhead due to re-calculating reference
  2. Pulley Reference
    • Calculate the reference signal magnitude at runtime relative to pulley - act as if the motor is driving the pulley rather than spool
    • Use dancer feedback to accommodate for the mismatch between the pulley and spool
    • Pros: Only need to calculate reference signal once per run (or upon input parameter change)
    • Cons: Feedback to motor is less direct
  3. Dancer Reference
    • Change the spool motor velocity based solely on the dancer extension. Speed up motor if dancer is going inwards, slow down if dancer extends.
    • Pros: Simple to implement
    • Cons: Not as precise, possibility of continuous speed fluctuation

Remaining Designs

The design for the pulley has been reviewed by Hanzlik and will look very similar to the design shown below.
Pulley Animation

Shared Team Vision for Week 11 Review


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