Gear Worm Flank Grooves for Lubrication and Self-Locking
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Solution Overview
Problem
Existing gear worm designs with lubricant reservoirs on tooth flanks reduce self-locking, which is undesirable in applications like motor vehicle actuators where maintaining adjusted positions is necessary.
Innovation Solution
Forming concentric grooves on the worm flanks using belt grinding, ensuring continuous lubrication while allowing direct contact between groove tips and mating teeth to adjust self-locking, with groove depth and radial spacing controlled for precise lubrication and contact area.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If lubricant reservoirs are formed on the tooth flanks of the gear worm, then reliable lubrication is achieved, but self-locking capability is reduced
Solution Approach 1:
The groove structure is designed with varying depth and width along the tooth flank, creating zones with different lubricant storage capacities. The grooves are deeper near the root and shallower toward the tip, ensuring optimal lubrication where contact pressure is highest while maintaining self-locking capability at the tooth tip where direct contact occurs
Solution Approach 2:
The groove structure allows dynamic adjustment of lubricant distribution based on operating conditions. During operation, the grooves supply lubricant to the contact zone, while at rest positions, the lubricant retreats into the grooves allowing direct contact between tooth surfaces, thereby providing adjustable self-locking capability
2Force
If continuous lubrication is provided to the gear teeth, then friction is reduced, but self-locking at stationary position is compromised
Solution Approach 1:
The groove structure creates a periodic lubrication pattern where lubricant is supplied during the engagement phase and retreats during the disengagement phase. This periodic action ensures friction is reduced during operation while self-locking is maintained when the gear is stationary
Solution Approach 2:
The lubricant is extracted from the continuous film and stored in discrete groove reservoirs. This allows the lubrication function to be activated only when needed during operation, while the tooth surfaces remain in direct contact for self-locking when stationary
3Quantity of substance
If groove depth is increased to improve lubrication, then lubricant storage is enhanced, but contact area with mating teeth is reduced
Solution Approach 1:
Instead of increasing groove depth uniformly, the groove structure transitions to a third dimension by varying depth radially and axially. The grooves are deepest near the root and shallower toward the tip, optimizing both lubricant storage in the root area and contact area at the tip area
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Ensures reliable lubrication and adjustable self-locking by maintaining lubricant in grooves, enhancing the gear's ability to hold adjusted positions without continuous lubrication film, suitable for mass production and reducing tooling costs.
Implementation Method 1
the flexible abrasive belt lies directly against the worm gear flanks in a tangential direction to the gear worm, so that circular grooves can be ground into the worm gear flanks
Implementation Method 2
the entire surface of the worm flanks is constantly supplied with sufficient lubricant
Data Source
Figure 1~2
Figure 3
AI summary
The invention relates to a method for producing a gear worm (12) which is located in particular on an armature shaft (14) of an electromotive drive unit (10), wherein firstly a worm gear (20) having screw flanks (22) axially opposite one another on a longitudinal axis (18) is formed by means of a rolling tool, and subsequently a groove structure (24) which is concentric about the longitudinal axis (18) is formed on the screw flanks (22) by means of an additional process step. The invention also relates to a gear worm (12) produced according to the method according to the invention, and to a transmission drive unit (10) containing such a gear worm (12).