worm gear

Abstract

A UK university group has developed 3D modelling called Virtual Reality Machining. Design of previously too complex components is possible, particularly in the field of transmission. A globoid worm-gear drive, with several advantages, is the first product offered for joint development and licensing. Partners will come from heavy machining e.g. elevators, military and mining. 

Details

Worm drives provide an effective way for high-ratio speed reduction and power transmission applications in a limited space using right angle, but non-intersecting shafts. When properly applied, worm drives provide the smoothest, quietest form of drives. There are a variety of worm drives applied in a wide range of applications. One of the state-of-the-art results of research and development is a globoid worm-gear drive.
The globoid worm-gear drive is quite different from the traditional cylindrical worm-wheel drive in that the worm is a globoid worm whilst the wheel is a standard involute helical gear. The tooth surface of the globoid worm is enveloped by a family of tooth surfaces of an involute helical gear.

Innovative Aspects:
With comparison to the conventional cylindrical worm-wheel drive, it has the following advantages:
• Better line contact.
• More teeth engaged.
• Higher load capacity.
• Better lubrication.
• A more compact size.
• Easier manufacturing.

Technology sector	- Design and Modelling / Prototypes - Industrial Manufacture - Traction/Propulsion Systems
Market application	- Industrial Equipment and Machinery - Mining machinery - Industrial trucks and tractors - Motor vehicles, transportation equipment and parts - Construction
Stage of development	Available for demonstration
Patent Rights (IPR)	Secret know-how
	The mathematical model is difficult to invent around. Joint patenting will be considered with partners for specific designs.
Cooperation type	- License Agreement - Joint further development - Testing of new applications - Financial Resources Type of partner sought: Industry, research. Specific area of activity of the partner: Heavy machinery; manufacturers of worm gears. Task to be performed: The university would be responsible for total design and test procedure, and the partners can be responsible for funding, manufacturing and commercial aspects. The group leader can attend the company or institute to join this work.
Organisation type	Research institute/University      Org. Size: > 500

worm gear

Abstract

A UK university group has developed 3D modelling called Virtual Reality Machining. Design of previously too complex components is possible, particularly in the field of transmission. A globoid worm-gear drive, with several advantages, is the first product offered for joint development and licensing. Partners will come from heavy machining e.g. elevators, military and mining. 

Details

Worm drives provide an effective way for high-ratio speed reduction and power transmission applications in a limited space using right angle, but non-intersecting shafts. When properly applied, worm drives provide the smoothest, quietest form of drives. There are a variety of worm drives applied in a wide range of applications. One of the state-of-the-art results of research and development is a globoid worm-gear drive.
The globoid worm-gear drive is quite different from the traditional cylindrical worm-wheel drive in that the worm is a globoid worm whilst the wheel is a standard involute helical gear. The tooth surface of the globoid worm is enveloped by a family of tooth surfaces of an involute helical gear.

Innovative Aspects:
With comparison to the conventional cylindrical worm-wheel drive, it has the following advantages:
• Better line contact.
• More teeth engaged.
• Higher load capacity.
• Better lubrication.
• A more compact size.
• Easier manufacturing.

Technology sector	- Design and Modelling / Prototypes - Industrial Manufacture - Traction/Propulsion Systems
Market application	- Industrial Equipment and Machinery - Mining machinery - Industrial trucks and tractors - Motor vehicles, transportation equipment and parts - Construction
Stage of development	Available for demonstration
Patent Rights (IPR)	Secret know-how
	The mathematical model is difficult to invent around. Joint patenting will be considered with partners for specific designs.
Cooperation type	- License Agreement - Joint further development - Testing of new applications - Financial Resources Type of partner sought: Industry, research. Specific area of activity of the partner: Heavy machinery; manufacturers of worm gears. Task to be performed: The university would be responsible for total design and test procedure, and the partners can be responsible for funding, manufacturing and commercial aspects. The group leader can attend the company or institute to join this work.
Organisation type	Research institute/University      Org. Size: > 500

Worm Gear

Description:

Worm Gear

Worm Gear Box

When worm-gear speed reducers are assembled, proper alignment of the worm and gear, and the resulting tooth contact pattern, is the most critical assembly variable. It is also the most difficult to control. Emerson Power Transmission engineers have developed and patented a new computerized mechanism to quickly and accurately align the worm and gear.

A typical worm-gear reducer assembly includes the input worm shaft straddle-mounted between ball bearings, and the output wormgear and shaft supported by tapered roller bearings. To produce these assemblies with acceptable worm-to-gear contact patterns, assemblers must position the worm-gear under the worm centerline accurately, and at the same time set output bearing endplay within a close tolerance, usually in the range of 0.002 to 0.003 in. This typically requires a trialand-error process that is neither cost effective nor precise. First, technicians apply bluing to the worm-gear, then assemble the reducer with shims either behind the bearing cups or under the retainers. Next, shim-pack thickness and location are adjusted until the correct combinationof contact pattern and bearing clearance is met. This can be time consuming, because the reducer may need to be assembled and disassembled repeatedly, and final quality depends on the skill of the assembler.

Gearing manufacturers have sought to shortcut this process by locating the theoretical worm-gear centerline relative to one bearing shoulder, and then using statistical average dimensions for bearing cup/cone stack height and housing bearing seat locations. With this technique, the same shim-pack is always used behind the rear-bearing cup, so the assembler need only adjust the outboard shim pack for correct endplay. This approach eliminates the need for bluing, but still requires disassembly of the outboard bearing retainer, and the resulting tooth contact pattern is only average at best.

It is commonly believed that a poor contactpattern will self-correct as the bronze gear wears-in over time, but the reality is that part of the worm-gear assembly's useful life is lost in the process. In addition, high contact stresses that result from a small initial contact area can cause premature scoring of the worm thread, which further accelerates gear wear while shortening life. The resulting high concentration of bronze serves to exacerbate the problem.

EPT's Emerson Gearing Div. resolved these various assembly problems by developing a computerized centering device that accurately measures each assembly component and automatically calculates exact front and rear shim-pack requirements.

First, the computer measures stack height of the output assembly. Next, the computer's master worm contacts the bronze gear and oscillates horizontally to find the exact centerline. The computer measures the reducer housing and output bearing retainer to determine the location of front and rear bearing seats relative to the housing face. A computer data screen shows the number and thickness of shims to place behind the front and rear bearing cups. This centers the wormgear and gives the desired bearing endplay.

The computerized process eliminates the need for bluing, dial indicators, multiple assemblies and disassemblies, and highly skilled assemblers. The result is a substantial saving in time, a perfectly centered tooth contact pattern, and accurate endplay settings.