Self-Centering Bar Guide With Spring-Loaded Oscillation Control
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Solution Overview
Problem
Current bar-centring systems for machine tools are ineffective in maintaining precise axial positioning and reducing oscillations and flexure in bars, especially at high rotation speeds, leading to damage and machining errors, and are structurally complex and costly.
Innovation Solution
A self-centring device with a frustoconical hollow containing body and movable centring elements that adapt to different bar diameters, using a helical spring for constant contact and a distributed guiding action, integrated with an advancement device for precise positioning and reduced oscillations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If current bar pusher devices are used to advance the bar, then the bar can be pushed forward, but the pushing action does not facilitate containment of flexure and swinging phenomena, making guiding and positioning more difficult
Solution Approach 1:
The guiding device is divided into multiple independent guiding elements (at least two) that are distributed around the bar's circumference. Each element can independently contact the bar and provide guiding force, allowing the system to effectively contain flexure and swinging phenomena through distributed support points rather than a single pushing action.
Solution Approach 2:
The guiding elements are arranged in a circumferential distribution around the bar, transitioning from a single-point axial pushing action to a multi-point radial guiding arrangement. This dimensional change allows the device to address flexure and swinging in multiple directions simultaneously, providing comprehensive containment of bar instability.
2Volume of moving object
If the diameter of bars is increased, then the section is larger, but the instability and flexure phenomena are not reduced because equal increase of rotation speeds causes oscillation and knocking problems
Solution Approach 1:
The guiding elements are designed with specific local properties including elastic characteristics and adjustable positioning capabilities. Each guiding element can independently adapt to the bar's local conditions, providing customized support forces at different circumferential positions to effectively dampen oscillations and reduce flexure phenomena regardless of bar diameter.
Solution Approach 2:
The guiding elements are designed to be movable and adjustable rather than fixed, allowing them to dynamically adapt to varying bar diameters and rotation speeds. This dynamic capability enables the system to maintain effective guiding and stabilization across different operating conditions without being limited by bar size increases.
3Manufacturing precision
If current centring devices are used, then some centring action is provided, but the structural and functional complexity is great, reflected in greater financial cost and unsatisfactory mechanical reliability
Solution Approach 1:
The guiding elements serve multiple functions simultaneously: they provide centring action, guide the bar during advancement, dampen oscillations, and support the bar against flexure. This multi-functionality eliminates the need for separate complex mechanisms for each function, reducing overall device complexity while maintaining effective centring and guiding performance.
Solution Approach 2:
The guiding elements are designed to automatically adapt to the bar's position and dimensions without requiring complex external control systems. The elements self-adjust through their elastic and movable characteristics, providing automatic centring and guiding action that simplifies the overall device structure while maintaining manufacturing precision.
4Object-affected harmful factors
If annular guide element is pushed to adhere to the bar and rotated for dynamic centring action, then noise and surface damage are reduced, but the structure is complex and requires connection to supply source for actuators
Solution Approach 1:
The invention extracts and eliminates the complex actuator system and external supply source requirements from the centring device. Instead of using powered annular guide elements with actuators, the solution uses passive guiding elements that rely on elastic forces and mechanical geometry to achieve the centring action, thereby removing the harmful complexity while maintaining the beneficial noise and surface damage reduction.
Solution Approach 2:
The guiding elements are designed as simple, inexpensive mechanical components without complex actuators or external power requirements. These straightforward mechanical elements provide effective centring and guiding through their basic elastic and geometric properties, offering a cost-effective and reliable alternative to complex powered systems.
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 provides a structurally simple, reliable, and cost-effective self-centring device that automatically adjusts to various bar diameters, significantly reducing noise, surface damage, and oscillations, while ensuring precise axial positioning and easy integration with existing bar-feeding apparatus.
Implementation Method 1
an elastic member (7) configured for urging the centring and guiding elements (6) to a position of minimal reciprocal distance so as to bring said elements (6) into contact with the surface of the bar (B)
Implementation Method 2
a helical spring for constant contact
Data Source
AI summary
An apparatus includes a self-centring device for centring and guiding a bar, tube or the like to be advanced to a spindle of a machine tool, includes a hollow containing body with through opening having a longitudinal axis, for receiving a bar to be fed along an advancement direction to the spindle; in the body an inner sliding surface is defined that is tilted with respect to the longitudinal axis; centring and guiding elements are provided housed in the hollow body and shaped for coming into contact with the bar and exert thereupon a distributed centring and guiding action; the centring and guiding elements that are slidable along the inner surface for the distance thereof from the longitudinal axis to adapt to different bar diameters; in the body an elastic member is housed to urge the centring and guiding elements to the position of minimal reciprocal distance so as to induce and maintain, during operation, the centring and guiding elements in contact with the surface of the bar. An advancement device is further disclosed for the bar, having a supporting and guiding member configured for restingly receiving, from a first side, a bar and configured for guiding said bar along an advancement direction, a movable grasping member mobile from a disengaged position, further from the member to be separated from the bar, to a locking position, nearer said supporting member to press longitudinally the bar from a second opposite side against the supporting member; advancement motor device is configured for rotating the supporting and guiding member and/or the movable grasping member in the locking position to draggingly advance the bar along the advancement direction.