Characterization and Manufacture of Bevel gear 1

[thunderspeed]

Hi all ,
I have bevel gear that works on ring gear (pinion and ring) simillar to the one in the following picture :

I want to charachterize the small bevel gear (pinion) to give the measurements to a workshop to manufacture copies for this gear or buy it.
Also I'd like to take an idea about the method of manufacturing those in workshop .

thanks in advance

 

[tbuelna]

Based on your OP, it appears you do not have much experience with gear engineering and manufacturing. So I would strongly recommend hiring an experienced consultant to assist with this effort. The consultant will know where to get the gear measured/analyzed, he will prepare all the engineering documentation required, he will specify the correct material/heat treatment/processing/QA required, he will help you prepare your purchase specification, and he will help you select a qualified vendor. It will cost a bit of money to hire a gear expert, but it is money well spent. Most importantly, the gear expert will make sure the gear is engineered to give the best combination of cost, quality and performance for your particular application. Trying to do this job on your own without having much prior experience will likely not end well.

In your particular case, I would also not recommend simply relying on a single vendor to both reverse engineer and manufacture the pinion. With your limited technical knowledge of gears, you would not be able to prepare a purchase specification with the necessary level of detail to ensure the product delivered is exactly what you require. Without a detailed purchase specification, you would be forced to accept whatever the vendor decides to deliver. Caveat emptor, right?

One additional benefit to hiring a consultant to do this work is that you will get first-hand experience doing this job properly from start to finish.

Best of luck to you.
Terry

 

[thunderspeed]

I understand that this job needs someone experienced to handle it .The old gears have been sent to a specialized workshop to make identical copies .Financial resources are very limited where I work.What I'm asking about is the methodology and measurements I would take either to accept the manufactured or purchased bevel . And in the future , what measurements and characteristics of the bevel gear I should send the manufacturer to order one without the need to send the old gear .

 

[mfgenggear]

thunderspeed

I do not have experience with this size of a beveled gear set. far as handling and tooling.
but Terry did answer the question. have the supplier who is making the gear" pay them" to get the reverse engineering.
all of the dimensional attributes, eg outside diameters, inside diameters, all the lengths, an on.
the gear data is very important. in order to know the material and heat treat characteristics there will have to be a met lab analysis. is it induction harden, through harden, case harden etc. if they are not qualified to do this then find someone who is. that have both metallurgical & mechanical gear engineering expertise.

have them put this on a blue print.

Mfgenggear

 

[tbuelna]

thunderspeed- I fully appreciate the position you are in with regards to budget constraints and limited expertise with gear engineering/manufacturing. And the recommendations I provided above took your situation into consideration.

"I understand that this job needs someone experienced to handle it .The old gears have been sent to a specialized workshop to make identical copies .Financial resources are very limited where I work."

To get the gear reverse engineered you will need to pay someone to perform this work. You chose to rely on the gear vendor to perform this task, but I gave you several reasons why it would be better for you to hire a consultant instead.

"What I'm asking about is the methodology and measurements I would take either to accept the manufactured or purchased bevel."

As I noted above, the acceptance requirements for your pinion should be explicitly defined on the purchase contract. The preparation of your purchase contract will require a thorough knowledge of every aspect of gear design and manufacture. It will also require someone with similar expertise to review the QA documentation submitted with the finished pinions to determine if they conform to the purchase contract requirements. Asking a vendor to "make identical copies" is basically meaningless. The vendor is free to determine whether the pinions delivered meet the definition of "identical copies".

"And in the future , what measurements and characteristics of the bevel gear I should send the manufacturer to order one without the need to send the old gear."

One reason I recommended hiring a gear consultant for this job was because it would allow you to experience firsthand the process required from start to finish, and it wouldn't cost anything extra.

 

[geesamand]

I guess some basic information would help us guide you to an economical result:
1) What RPM are the input and output?
2) What diameter is the main gear?
3) What service is this bevel set?

It's important to understand that in some kinds of gearing, a complete reverse-engineering effort can yield a suitable replacement for one piece in the set. Spur and helical gearing can be reverse engineered in most cases, if you're willing to invest in enough measurement and engineering effort.

Bevel gearing is often crowned using machine settings and lapped to the pinion, meaning that without the main gear it's impossible to make a reasonable replacement pinion. Bevel gearing with spiral or curved forms are also produced with many machine settings that are not included in a drawing. So even if you were the original manufacturer, it might not be reasonable to supply a single pinion without testing it against the mating gear.

 

[tbuelna]

geesamand-

From the photo provided it looks like those are straight bevel gears. But as you noted, due to the fairly significant ratio between the pinion and gear, and relatively wide face, you would expect there to be a fair bit of geometry modification (crown, lead compensation, tip relief, etc) applied to the tooth profiles.

With a gear set that large, I would also expect the pinion face to be wider than the gear face width, which does not seem to be the case.