In order to grind gears burn-free and as productively as possible, a better understanding of the process is required. This is especially important for gear profile grinding, due to the complex contact conditions between workpiece and grinding wheel. In this article, an analogy process and a process model will be presented in order to gain a closer look into the process. Finally, different process strategies will be analyzed using the presented process model in order to give examples for the use of the described calculations.The paper goes into reasonably great detail in explaining and describing the process model in order to increase gear grinding efficiency and effectiveness. You can find the .pdf of the paper here.
Some Deep Thinking on Gear Grinding
We stumbled across a paper online, titled "Optimization of the Gear Profile Grinding Process Utilizing an Analogy Process," by Christof Gorgels, Heiko Schlattmeier, and Fritz Klocke. The paper goes into the novel problems posed by the improving gearing materials and the need by gear manufacturers to cut costs in gear grinding.
Are You A Fan of 'How It's Made?'
If you are, then you should check out this video, from Machine Tool Systems. It's about CNC gear grinding. It even sports a cheesy/retro soundtrack to keep you enthused. It's definitely worth checking out.
AGMA Training Coming Next March
Don't forget to register for the annual Basic Training for Gear Manufacturing taking place March 10 through 14 at Daley College in Chicago. The training session is meant to help everyone the knowledge and productivity of everyone training. There will be classes offered in many fields of gearing:
- Gearing and nomenclature
- Principles of inspection
- Gear manufacturing methods
- Hobbing and shaping
A Tiny Transmission
We know that spur gears (also known as straight cut gears) are used in a variety of applications. They're not often used in auto transmissions, though. So check out this application of spur gearing: A two-speed transmission of the XRAY NT1 Raycer 1/10th Nitro Race Car. This radio-controlled car features precision spur gear for a two-speed power transmission.
The 2-speed transmission parts are installed on a precision-manufactured super-smooth 2-speed middle layshaft made from tough HUDY shaft steel, additionally heat treated for extra strength and long lifespan. The 2-speed gear adapter is CNC-machined from Swiss 7075 T6 for precise fitting of the 1-way bearing, allowing super-precise and wobble-free installation of spur gears. The high-quality German 1-way bearing is hand-ground before installation for maximum running precision and strength. The 2-speed adapter is manufactured from hardened steel.It sounds like a pretty sweet radio car. I know I wouldn't mind getting one for Christmas this year.
How do you make a wooden router lift?
Here’s a “neat” post for a Friday. I found a really interesting How-To guide on building a wooden router lift. An enterprising fellow up in Canada had some specific design constraints for building his router lift and he decided on using wood. You might be wondering at this point, how does this relate to gearing? Well, part of the router lift apparatus involves creating a crank, which calls for some gearing solution, which had to be made from wood, obviously.
The whole process (he’s provided step by step descriptions and photos) is really cool, but seeing how he fabricated the wooden gears is extremely interesting. You should check it out!
Gearp Application Chart
We stumbled upon a pretty basic--but definitely useful--gear application chart that helps you determine, depending on your application, which kind of gear you should use. Here's what it says under Bevel Gears,
Suitable for 1:1 and higher velocity ratios and for right-angle meshes (and other angles)...The entire chart is worth checking out. Even if presently, you only use one type of gear (a worm gear, say) it's good to know what other sorts of engineered solutions are out there.
Good choice for right-angle drive particularly low ratios. However, complicated tooth form and fabrication limits achievement or precision. Should be located at one of the less critical meshes of the train.
Teaching Gears Young
There's a nice story out of the News-Gazette of Champaign, IL about youth education in engineering. The South View Middle School is stepping up its science-technical educational efforts and it seems to be a hit with the students. While students get to work in groups, brainstorm, and develop their math-science skills, they also engage in hands-on learning.
Eighth-graders Andrew Nelson and Joby Means, who have been studying mechanical gears and how they are used, build a bevel gear with materials from a kit.Even if not every student--likely--in the program goes on to an engineering degree, the school is definitely planting the seeds for the engineers of tomorrow.
"This was easy," Joby said, turning a crank to make the gears move. Soon, students will learn how to move the gears using a computer program.
Like Jelicia and Ashylee, Andrew said he didn't know whether he would like the pre-engineering activities, which he started in sixth grade. But Smith's classes quickly became his favorite, and he's looking forward to continuing them in high school and college.
How To Make A Clock From Gears
Here's a fun video for a Friday! An engineer named Alan Parekh has uploaded to YouTube his method for creating a cool-looking clock out of CNC-cut gears. It's pretty impressive. I know I want one in my shop, now.
Via Crunch Gear
Gearbox Failure Common in Subaru Impreza WRX?
AutoSpeed has a really awesome breakdown of a widely known problem with the Subaru Impreza WRX and Liberty RS: Namely, that the five-speed manual gearbox is prone to failure. They note,Keenly driven WRX/RSs with engine mods are likely to experience gearbox failure. This is largely due to the immense traction of the Subaru all-wheel-drive system, which (on a dry road) doesn't allow engine torque to be dissipated into wheelspin. Furthermore, those mechanically tweaked Subarus with an aftermarket (ie non-slipping) clutch will trap even larger stresses in the driveline. Without doubt, an up-rated clutch is a big contributing factor to gearbox problems.They go on to note that the gearbox has a common point of failure; the teeth are stripped from the first and second drive gears. The article poses a few possible reasons for this failure, and suggest an aftermarket product, the Middleton Rally Team’s heavy-duty dog gearset. The only major downside to the MRT gearset is its noise-level, which is somewhat fierce.
Until a helical cut dog box comes along, we'd have to say that the MRT gearset is only for those drivers that like to play on weekends - there's no way you could put up with the noise of a dog box in an everyday vehicle. Motorsport - such as rally, circuit and drag racing - is this product's biggest outlet. Apparently 80% of MRT's present dog box sales are for rally cars - where, obviously, gearbox noise is of no importance.
Bevel-Helical Gears Drive Huge Floating Conveyor In Hungary
At a mining plant in Hungary, SEW-Eurodrive has constructed a huge floating conveyor belt powered by parallel shaft helical and helical-bevel gear units. The plant floats on a lake in Hungary, about two hours from Budapest. It is over 200 meters long and descends to depths of up to 50 meters in the 40,000 square meter lake. The conveyor-plant apparatus transports gravel across eight stages to a nearby plant at a rate of up to 200 tons per hour.
Even though there is no ground beneath the conveyor, it is completely stable and rigid as it floats on pontoons. The bevel-helical gear-driven belts start and stop jerk-free with a 30% excess of power. The whole rig was completed after a very brief six-week construction period. It now supplies construction and filling material from the lake.
How do they make wind turbines?
There is a nice article in American Machinist this week about the production of wind turbines for wind-power machines. It goes into detail about all the work that goes into creating a wind machine, from fabrication to milling.
Many wind turbine component shops process such parts as gear case assemblies, planetary carriers and hubs on horizontal boring mills. These machines, with contouring heads and programmable boring bars, can reduce the number of tools, and tool changes, required to complete parts.
One tool can bore multiple diameters and produce complex part geometries. A contouring head combined with a programmable boring bar can perform as many as nine to ten different operations – atypical for a boring mill. Operations include threading, grooving, turning, contouring, taper turning and more, internally and externally, and rightangle heads and precision rotary tables add capabilities for five-sided part processing in single setups.
The whole article is worth checking out if you're interested in the process of industrial design, fabrication, and milling.
Gearing Advances Drive Air Jellyfish Robot
That's a heck of a title, but I just read an article that lives up to it. It's about how the United States Navy is developing robotic jellyfish that use energy harvesting technology to travel and surveil the oceans for time measured in years. The first prototype--designed by a consortium of universities from around the country--is called AquaJelly.
AquaJelly is an artificial autonomous jellyfish which consists of a translucent hemisphere and eight tentacles for propulsion. AquaJelly's translucent dome houses an annular control board with integrated pressure, light and radio sensors. AquaJelly has a watertight laser-sintered body that houses a central electric motor, two lithium-ion polymer accumulator batteries, the charging control unit and the actuators for the swash plate.Engineers are currently working on developing actuators that would convert energy from the surrounding ocean into usable energy to power the AquaJelly. I'm a little dubious of how effectively they can carry off such a project since it seems like they're trying to build a sort of perpetual (or very, very long-lasting) motion machine.
University engineers are also working on a similar creature for use in the sky rather the sea. It's called the AirJelly, and its
sole source of power is two lithium-ion polymer accumulator batteries rated at 8V and 400 mA, which can be completely charged in half an hour. It transmits the force to a bevel gear and from there to a succession of eight spur gears, which move the eight tentacles of the jellyfish via cranks. Each tentacle is designed as a structure with Fin Ray Effect. AirJelly is the first indoor flight object with peristaltic drive.The creature is fairly impressive (if impractical-seeming). I don't know how effective an eight-legged air jellyfish will be at surveying and obtaining information, but I do know that this is one of the most novel applications of gearing technology I've seen yet.
Want to know more about metal casting?
There’s a good piece in the latest Gear Solutions Magazine about metal casting and different types of metals, which is something that’s not solely related to gear manufacturing, but it’s something that underlies just about the entire industry. It’s worth a read.
Sand Casting: This is the oldest known method of producing an intricate casting. Molten metal is poured into a non-permanent sand mold that has been prepared with a pattern. Green sand molds use synthetic sand or sand in its natural or green state, i.e. damp sand still containing moisture. The sand must be cohesive and refractory (withstand heat without fusing), permeable (porous enough to let gases escape), and strong enough to support the weight and cores. Such a cast gear, even with extra care, can only achieve a quality level of A14.
Did someone else think of it first?
Did you know that (among the rest of its apparent plans for World Domination) Google has created a service called Google Patents? With it you can search the United States Patent and Trademark Office (USPTO) library of over 7 million patents and 1 million patent applications.
Google is using the same technology as it uses for Google Book Search; it has converted the entire image database of the USPTO into a text-searchable database. It is, to say the least, a diverting pastime to browse this extensive service. Here are a few interesting gearing patents.
Improvements in gears and gear teeth structures for use in driving assemblies, such as machines, vehicles and the like, wherein the teeth portions of the gears and, in certain instances, other portions thereof, are coated with a hard synthetic diamond material deposited thereagainst as carbon...
A gear-shaped tool (30) having stock removing surfaces (38) is rotated together with a bevel or hypoid work gear (32) in accordance with their respective number of teeth, and the gear-shaped tool 30 is also moved relative to the work gear (32) in the manner of a theoretical generating gear (46)...
A method is disclosed wherein standard generating motions for the production of bevel and hypoid gears are modified by the substantially simultaneous inclusion of additional controlled motions which enable a desired tooth surface geometry to be produced on the gears.If you're interested in gears specifically or any other manner of thing, Google Patents is a neat resource--for both professional research and recreational browsing.
Gears! What are they good for?
We talk a lot on this blog about gears, and we take for granted that our readers know all about the subject matter. But since we’re getting some new readers, we thought it would be a good idea to cover some gear basics. To start out, a gear is just a part of a transmission device; it helps transmit rotational torque by applying force to another gear or toothed piece of equipment. Gears are found, for instance, in the transmission of your car and, of course, on your bicycle. They allow you to multiply your force or to change the rotational speed or direction of a force.
Gears are extremely useful because of this force multiplication. Since the rotational speed of a gear is in proportion to its circumference and speed of rotation, a larger gear will turn more slowly than a smaller gear with which it’s meshed. Think of bicycle tire spinning: The outside edge of the tire is spinning slower than the inside edge, but both edges are making the same number of rotations. A larger gear has more teeth than a smaller gear, so when the two meshed gears are turning, the smaller gear will have made more revolutions than the larger gear. This relationship is called the “gear ratio,” and it generates the mechanical advantage of gears.
Gear ratio is the relation between the number of teeth on two gears that are meshed.
You can express this relation mathematically. For example, if one gear with 26 teeth is driven by a gear with 14 teeth, the gear ratio is 1/1.86, or 1:1.86. (That is, the mathematical expression of gear ratio is the number of teeth on one gear divided by the number of teeth on the other gear, basically.) A piece of equipment’s gear ratio is used to determine its performance and capability.
(An automobile transmission: Look a those gears!)
We hope that this little post helped to clear up some questions about what exactly gears are and how they function in a practical, day-to-day capacity!
Have you ever wondered how four-wheel drive works?
Earlier this week I covered how helical gears are found in the latest video game equipment. Today, I found a post on Pitchcare Magazine's website about how the new Kubota tractor is gaining traction from its bevel gear-driven 4WD system,
The operator can enjoy many hours of use without fatigue, as Kubota have, as always, put a lot of emphasis on driver comfort. The full hydrostatic power steering, matched with Kubota's bevel gear 4WD system means light, responsive, tighter turning for maximum productivity.Really, bevel gears are ideal for applications like this. In a four-wheel drive system, all four wheels need to be driven simultaneously (obviously). Therefore, the drivetrain needs to turn both axles. The way a bevel gear works is by connecting shafts at 90 degree angles (generally, although they can connect shafts at different angles). Therefore, since the driveshaft is perpendicular to the wheel axles, all four wheels can be turned simultaneously. The same principle applies to four-wheel drive automobiles.
I hope this post helped illustrate how something we take for granted--four-wheel drive--is actually the result of a fairly elegant engineering element.
$300 for a video game controller? Must be the helical gears!
I noticed some gear news tucked into a press release for a new Logitech video game steering wheel:Logitech (SIX: LOGN) (NASDAQ: LOGI) today announced the Logitech® G27 Racing Wheel. Designed to deliver the definitive sim racing experience for the PC and PLAYSTATION®3, the G27 features a powerful, dual-motor force feedback mechanism that smoothly and accurately delivers high-fidelity force effects to the hand-stitched leather wheel, so you can feel traction loss, weight shift, and the surface of the road. The helical gears deliver exceptionally quiet steering action, virtually eliminating noise and unwanted vibration.It is neat to see the peripherals manufacturer giving some credit to the inner components that make its products actually work well. For the record, helical gears are types of gears whose teeth are not set parallel to the axis; that is, they're set to an angle (which makes them appear in the shape of a helix, from the outside). They run more quietly and smoother than the more common spur gear.
On the Car that Saved BMW
There's an interesting article about the BMW 700--ie, the Car That Saved BMW--in the Sydney Central. Apparently, back in the 50s, BMW was not the cultural icon that it is today. At the time, it was a motorcycle manufacturer, but the motorcycle business was going south pretty rapidly. The company's automobile manufacturing business was also tanking, and things looked fairly bleak.Enter the BMW 700. By using as much of the previous model--the 600--as possible and redesigning where necessary, BMW was able to come up with a unique, compelling car. And in the center of it all, we find--a bevel gear differential:
Further features carried over from the BMW 600 were the all-synchromesh four-speed transmission as well as the bevel gear differential and, the flat-twin power unit originally used on BMW motorcycles and now increased in size from 600 to 700cc.The newly introduced 700 was a success, and the now-legendary automaker got a second chance at life.
When (Gear) Worlds Collide
There's some recent news from Engineerlive.com about a new gear design from Rotalink. Apparently, the company has created a new design that combines spur and planetary gear stages within a standard ovoid gearbox. The company claims the design results in a 400% torque increase.
Gear Manufacturer News Flying Under the Radar
Here's a little bit of gear manufacturer news that flew under the radar. Gear Technology, a California-based gear manufacturer that specializes in manufacturing gears for the aerospace, military, and commercial industries agreed to provide its services to Triumph Aerospace Systems. The deal reached agreement at the beginning of July 2009. The deal is expected to last five years with Gear Technology manufacturing precision machine gear equipment, including shafts, splined rings, and splined spacers for the military's V-22 Osprey Tilt-Rotor Aircraft.
How Much Sugar Can Thirty-Eight Tons of Gear Process?
On Monday it was announced that the industrial supplies giant Bearing Man Group commissioned two sugarcane mill drives at its Zambia-based Nakambala sugar mill. The gear units are capable of a peak output of 4 million Newton meters of torque, which should add quite a bit of crushing force to the mill, to say the least.
The gears' design consists of a primary helical gear stage, a secondary planetary stage, and a main load distribution stage at which power is split and distributed into the final-stage gear sets. Driving the gears is are 850 kilowatt, six-pole electric motors. The gears were manufactured , assembled, and tested in Germany; they were then disassembled and shipped to Zambia. If it's true that you can't make an omelet without breaking some eggs, it's equally true that you can't make something sweet without crushing some sugarcane. Assuredly, the world will be a sweeter place.
More Gear News Out of India
In other news, Shanthi Gears, a Coimbatore, India-based gear manufacturer, recently announced the end of a lock-out in its six manufacturing plants. On 20 July 2009, the company had announced a scheduled lock-out that seems to have been incited by its firing approximately 200 apprentice workers. Fired workers retaliated by gathering in protest in front of Centre of Indian Trade Unions and throwing stones at a company bus. The company stated that the firings were due to the recent economic slowdown.
Roller Chain Manufacturer Acquires Gear Manufacturer
In a bit of horizontal building, LG Balakrishnan & Bros Limited, a Coimbatore, India-based roller chain manufacturer has recently acquired MM Gears Pvt Limited, which is also based in Coimbatore. MM Gears is known for manufacturing worm gearboxes, helical gearboxes, geared motors, and non-standard gearboxes.
Coimbatore is situated on the banks of the Noyyal River and is the second-largest city in the state of Tamil Nadu. Its primary industries are engineering and textiles. Coimbatore also houses the majority of India's hosiery and poultry industries.
Coimbatore is situated on the banks of the Noyyal River and is the second-largest city in the state of Tamil Nadu. Its primary industries are engineering and textiles. Coimbatore also houses the majority of India's hosiery and poultry industries.