Revision as of 02:07, 30 November 2012

Group 24 - Cyclo HBB Parallel Shaft Helical Gearbox with Cyclo Reducer Input

Project Management: Coordination Review

Cause for Corrective Action

Group Challenges

Resolved Challenges:

During the reassembly of the Cyclo HBB Buddy Box our group faced many challenges. First and foremost we faced a significant time restraint. Our product required the use of the Machine shop in order to be reassembled. However, the machine shop hours do not coincide with the hours of the dissection lab. This proved to delay our reassembly significantly. We managed to overcome this challenge by skipping other courses, sacrificing part of our grade for some of those courses. This has proven to be a common requirement to do well in MAE 277.

Secondly our group faced the challenge of transporting our product. The HBB Buddy Box weighs approximately 60 pounds and it very unwieldy and hard to carry. We were required to move it from the dissection lab to the machine shop, lift it onto and off of the press multiple times, turn it, support it, and manipulate it in many ways during the course of the reassembly. This proved to be an exhausting and very difficult step to the project. By taking turns, working together, and just accepting that it needed to be done we were able to overcome this challenge.

Finally, our last challenge during the assembly of this project was balancing and finessing the assembly of a few of the subsystems. When we were inserting the ball in the ball bearing case of the shaft (Step 8) one of us needed to suspend the gear perfectly center while the other carefully inserted bearings making sure not to knock any of the out of the track or move the gear at all. The other assembly that was very difficult was the reducer. In order to assemble the reducer we needed to make sure that many loosely connected pieces stayed in place until the entire assembly was complete and the components finally secure. Both of these challenges were very frustrating and required an enormous amount of patience and determination.

Unresolved Challenges:

Our main unresolved challenge, as a group, is balancing the enormous workload from this course with the work load from our other courses. All of us feel as though our ability to master the material in our other, more fundamental, engineering courses is suffering because of this introductory level course. In order to pass this course we feel the need to pour hours upon hours of our time into this project. Unfortunately this forces MAE 277, a complimentary course, to become a priority over our primary engineering courses - threatening, not only our graduating date, but also our ability as engineers. We understand that the material that we are learning in this course is of a much different breed, and arguably of equal or greater importance, to the material in our other courses. However, upon communicating with other students we are confident that we are not alone in feeling that the goals in the course are overzealous and outside the realm of undergraduate study. We plan to overcome this challenge by doing the best that we can possibility do given the time constraints that we have. We will work incredibly hard, prioritizing which courses must be sacrificed during times of high work load (mainly from MAE 277). We will also accept the fact that we cannot do anything greater than our best given each of our unique circumstances.

Intergroup Challenges

Resolved Challenges:

We were able to work through our main scheduling conflicts as a group and everybody was able to pitch in during this gate. We accomplished this by being clear about when and where we were going to meet after discussing the options that we all had available to us. Planning, luck, and willingness to sacrifice other courses came in very handy during this gate. We were able to resolve this challenge by admitting that the incredible workload of this course absolutely needed to get done so we did what we had to do.

Unresolved Challenges:

Over the course of the semester the work load between group members has not been evenly distributed for a number of different reasons ranging from abilities, scheduling conflicts, missed meetings, and desire. This, once again, caused a few of the group members to receive a higher work load during this gate. This discrepancy was not due to the lack of willingness to work in this case, but the lack of expertise in the technical details of the project. Unfortunately, in order to get the gate done in time this could not be avoided. We plan to resolve this problem by redistributing the workload during the final gate, letting the more experienced members review and check the work of the less experienced members before it is posted to the wiki. In this way the workload will be more evenly distributed and the less experienced members will become experts in the project.

Another unresolved challenge was, once again, related to scheduling conflicts. A few group members literally cannot make it to the machine shop during the day. Therefore, the responsibility for assembling every component that required a press fell strictly onto the members that could actually make the meeting. This could not be avoided at all and is strictly due to the many restraints that crop up during academic projects. We plan to resolve this problem by redistributing the workload to make up for it during the final gate.

Product Archeology: Product Explanation

Product Reassembly

Upon dissecting and reassembly the Cyclo HBB Buddy Box it is clear that it was originally assembled by a machine. Many of the parts require a press, and the ones that do not still require very precise fits. Also, the difficulty level of some of the steps indicates that it would be too time consuming, too costly, and too frustrating to be assembled by hand. Finally, while we were assembling the HBB Buddy Box we noticed that there were many areas in which it would be far too easy to damage the product while assembling it by hand. Using robotics and machinery to assemble this product would allow for very precise and extremely challenging steps to be done quickly and more cost effectively. The utter weight of this product alone is an indicator that machines were used to assemble this product. It would be dangerous and extremely cumbersome for employees to be moving, flipping, and otherwise handling this product during the assembly.

• The assembly was exactly the same as the disassembly in reverse order.

Difficulty	Stars
Easy
Somewhat Difficult
Difficult
Very Difficult
Extremely Difficult

Notice: Press is required for assembly.

Step	Difficulty	Description	Picture
1	Difficulty:	Screw in one oil plug and one breather into the two oil plug holes on the casing.	300px
2	Difficulty:	Screw in the other two breathers into the two breather holes on the casing.	300px
3	Difficulty:	Slide the gear into the gear box.	300px
4	Difficulty:	Attach the Face Plate to the casing.	300px
5	Difficulty: This step received a difficulty of two because it was tedious.	Thread each of the eight screws through the Face Plate into the Casing, securing the Face Plate to the Casing.	300px
6	Difficulty: This step received a difficulty of four because it required a press.	Press the shaft and the shaft key into the gear slot.	300px
7	Difficulty: This step received a difficulty of four because it required a press.	Press the Ball Bearing Casing onto the Shaft.	300px
8	Difficulty: This step received a difficulty of five because it is very hard to suspend the gear while placing the bearings into the track. None of the bearings were secure until most of them were put back into place. While we were adding more bearings, the previous bearings would fall out of the track.	Insert Ball Bearings into the track made between the shaft and the casing. These bearings prevent the gear and the shaft from shifting in the casing while still allowing rotation. Make sure that the bearings are actually in the track and that they have not fallen just under the track. If one or more have fallen just under the track you will not be able to center the gear to continue adding bearings.	300px
9	Difficulty: This step received a difficulty level of two because of the precise fit of the seals.	Insert two rubber seals around the exposed part of the top side of the shaft.	300px
10	Difficulty: This step received a difficulty level of two because of the precise fit of the seals.	Insert two rubber seals around the exposed part of the bottom side of the shaft.	300px
11	Difficulty:	Slide the Thrust Plate over shaft of the Taper Bushing.	300px
12	Difficulty: This step received a difficulty level of three because it took quite a bit of force to screw the Taper Bushing back into the Shaft.	Screw the Taper Bushing into the threaded slot of the Shaft.	300px
13	Difficulty: This step received a difficulty of two just because it was tedious.	Screw the six Bushing Screws into the Taper Bushing, expanding the gap between the Thrust Plate and the head of the Taper Bushing.	300px
14	Difficulty:	Slide the two seals onto the shaft of the pinion.	300px
15	Difficulty: This step received a difficulty of four because it required a press.	Press the pinion onto the Taper Grip Bushing. Make sure to align the teeth of the Pinion with the grooves on the Taper Grip Bushing.	300px
16	Difficulty: This step received a difficulty of four because it required a press.	Press the High Speed Shaft Ball Bearing A onto the High Speed Shaft.	300px
17	Difficulty:	Slide the High Speed Shaft into the High Speed End Shield.	300px
18	Difficulty:	Slide the spacer onto High Speed Shaft.	300px
19	Difficulty: N/A The difficulty here is not applicable because we were unable to complete this step.	Clip the snap ring onto the High Speed Shaft to secure bearing and the spacer. This step makes sure that the assembly remains secure to the High Speed End Shield. We could not complete this step because the clip broke during disassembly.	There is no photo available for this step.
20	Difficulty:	Slide the Eccentric Bearing Key into the slot onto the High Speed Shaft.	300px
21	Difficulty: This step received a difficulty of four because it required a press.;;	Press the Eccentric Bearing onto the High Speed Shaft. Make sure to line up the key slot on the eccentric bearing with the key that is on the high speed shaft.	300px
22	Difficulty: This step was difficult because of it was challenging to slide the Cycloid Disk around the offset bearings on the Eccentric Bearing.	Slide the Cycloid Disk onto the lower part of the Eccentric Bearing. Make sure it is secure around the lower part of the bearing and ensure that it does not fall below. Make sure that the etchings on the disk are face up and visible, this will be important in a later step.	300px
23	Difficulty:	Slide the Cycloid Disk Space around the Eccentric Bearing.	300px
24	Difficulty: This step received a difficulty of two simply because of the precise fit between the Cycloid Disk and the Eccentric Bearing.	Slide the second Cycloid Disk onto the upper part of the Eccentric Bearing. Make sure that the etchings on the disk are face up and visible, this will be important in the next step.	300px
25	Difficulty:	Make sure that the etchings of the Cycloid Disks are aligned as shown in the accompanying photo. The matching etchings should oriented 180 degrees opposite of one and other.	6000 Series Cyclo HBB Manual
26	Difficulty:	Slide the spacer onto the High Speed Shaft.	300px
27	Difficulty: This step received a difficulty of four because it required a press.	Press the High Speed Shaft Ball Bearing B onto the High Speed Shaft.	300px
28	Difficulty: N/A The difficulty is not applicable because we were unable to complete this step.	Attach a snap ring onto the end of the high speed shaft, securing the entire assembly below. We could not complete this step because the clip broke during disassembly.	There is no photo available for this step.
29	Difficulty:	Set the Ring Gear Housing onto the High Speed End Shield. Make sure that it sits securely into the grooves of the end shield.	300px
30	Difficulty: This is difficult because it is very hard to set each of the pins and rollers into the slots while simultaneously making sure that they sit nicely in the tracks, while also keeping the Ring Gear Housing Securely Attached to the High Speed End Shield.	Insert the ring gear housing pins and rollers into the Ring Gear Housing. Make sure that the Cycloid Disks are aligned correctly as specified in Step 25. This is critical to the performance of the Reducing Mechanism. Make sure that all of the housing pins sit securely into both the groove of the Ring Gear Housing and the bearing track of the High Speed Shield.	300px
31	Difficulty: This step received a difficulty of four because it required a press.	Press the Pinion and the Taper Grip Busing Assembly into the Gear Box. Make sure that the Pinion Teeth are aligned with the teeth of the Gear. If they are not aligned you will not be able to press the assembly into the Casing.	300px
32	Difficulty: This step received a difficulty of four because it required a press.	Press the Ball Bearing simultaneously around the end of the pinion shaft and the hole in the bottom of the gear box. Make sure that the Ball Bearing is Flush with the bottom of the Pinion shaft. Make sure that the face of the Taper Grip Bushing is flush with the face of the Casing. The Ball Bearing and the bottom of the Pinion Shaft will NOT be flush with the bottom of the Casing.	300px
33	Difficulty:	Slide the eight Slow Speed Rollers around the eight pins on the Taper Grip Bushing.	300px
34	Difficulty: This step received a difficulty of five because it is extremely challenging to pick up the entire reducer subsystem and slide it onto the pins of another subsystem while making sure that none of the components of the reducer subsystem move out of place.	Slide the holes of both, offset, Cycloid disks around the Slow Speed Rollers, and the pins on the Taper Grip Bushing. Make sure that disks remain in the position specified in Step 25. If you are having trouble with this step, make sure that the Cycloid Disk Spacer is not blocking any of the holes.
35	Difficulty:	Slide the High Speed Shaft Oil Seal onto the High Speed Shaft.	300px
36	Difficulty:	Slide the key into the key slot on the expose part of the High Speed Shaft.	300px
37	Difficulty: This step received a difficulty of four because it required a press.	Press the Lovejoi Connector onto the end of the High Speed Shaft. Make sure that the key slot on the Lovejoi is lined up with the key that is on the High Speed Shaft.	300px
38	Difficulty:	Slide the eight bolts on the Input HUB through the eight holes of the High Speed End Shield and the Ring Gear Housing.	300px
39	Difficulty:	Slide the eight spring washers onto the eight exposed bolts from the Input HUB.	300px
40	Difficulty: This step received a difficulty level of two just because it was tedious.	Secure the assembly by threading the eight nuts onto the exposed part of the eight bolts from the Input HUB	300px

Mechanisms

The key component of the SMCyclo Helical Buddy Box is the parallel helical gear mechanism. A gear would be similar to a lever with the added feature of rotating continuously instead of rocking back and forth through a short distance. The parallel helical gear’s function is to transfer the rotational energy that is produced from the reducer. The rotational energy is transferred to a shaft with a helical gear fused around its diameter. The angled teeth then grip onto the angled teeth located around the diameter of the gear. The gear then transfers the energy applied to the shaft which is statically locked with the gear due to a key and a key slot that is shaped on the inside diameter. This rotational energy is then transferred up the shaft to whatever application is necessary.

The relationships for a gear are based on the diameter, the number of teeth on each gear and the rotational velocity of gears. With helical gears, the tooth of each gear is set at a distinct angle. This angle is dependent on the amount of noise created, stress tolerances, and the maximum torque that can be applied to each tooth. Due the flexibility of this variable, the designs of each tooth can be modified for multiple applications and load capacities.

For all necessary equations refer to the Equation Sheet from Boston Gear.

Design Revisions