Projectile Bearing Unit Axial Spring Preload
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The existing guided ammunition projectile bearing units suffer from brinelling due to high acceleration forces during firing, leading to unwanted effects on the running behavior and controllability, particularly due to excessive friction and potential damage from high launch loads.
Innovation Solution
A bearing unit design featuring a roller bearing system with a spring element that prestresses the second ring axially during firing, allowing the projectile parts to move apart in flight, reducing axial loads on the bearing and incorporating a support element to manage the weight and acceleration forces, ensuring low-friction and constant rotation, and utilizing ceramic ball bearings for high rigidity and preload.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a roller bearing is used to connect projectile parts, then the projectile parts can rotate freely about the longitudinal axis, but the bearing suffers from brinelling due to high acceleration forces during firing
Solution Approach 1:
A spring element is introduced between the second ring and the second projectile part to absorb and cushion the high acceleration forces during firing. The spring element compresses under the launch load, preventing these forces from being transmitted directly to the roller bearing, thus avoiding brinelling damage while allowing free rotation during flight
2Reliability
If the projectile parts are held together in the barrel position, then the bearing unit is protected during storage, but the bearing unit is subjected to high loads during firing
Solution Approach 1:
The bearing unit is designed to dynamically change its state between two positions: in the barrel position, the projectile parts are held together with the bearing protected; during firing, the spring element allows the parts to separate axially, reducing the loads transmitted to the bearing while maintaining rotational capability
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
The solution prevents damage to the bearing unit under high acceleration, maintains free rotation of the tail unit, and ensures consistent control by dissipating launch forces, thereby enhancing the reliability and accuracy of the projectile's flight.
Implementation Method 1
The bearing unit contains a spring element which, in the barrel position, prestresses the second ring in the axial direction in a firing direction of the projectile relative to the second projectile part with a prestressing force.
Implementation Method 2
The bearing unit contains a - in particular axially guiding - roller bearing with a first and a second ring and rolling elements
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A bearing unit (12) for a projectile (2) of guided ammunition, wherein two projectile parts (8a,b) are connected by means of the bearing unit (12) and are displaceable and rotatable relative to each other, comprises a rolling bearing (18) with first and second rings (20a,b) and rolling elements (22), wherein the first ring (20a) is fixed to a first mounting section (28a) of the first projectile part (8a) in the axial direction of a longitudinal axis (4) and the second ring (20b) is mounted to a second mounting section (28b) of the second projectile part (8b) so as to be displaceable in the axial direction, and a spring element (46) which, in a tube position (R), pre-tensions the second ring (20b) in the axial direction relative to the second projectile part (8b) and transfers the projectile (2) from the tube position (R) to the flight position (F) after its firing. A projectile (2) contains the first (8a) and second projectile part (8b) and the storage unit (12).