Bar Stock Gripper and Guide for Vibration-Free Feeding
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Solution Overview
Problem
Existing bar feeders in machine tools face issues with vibrations and lubrication challenges, particularly when handling bars of varying dimensions and non-circular cross-sections, leading to reduced productivity and increased costs due to the need for frequent channel replacements and lubrication systems.
Innovation Solution
A support and gripping unit with tubular shells and switchable jaws, powered by a linear fluid actuator, provides high flexural stiffness and adaptable clenching capabilities to minimize vibrations and eliminate the need for lubrication, allowing for efficient machining of bars with any cross-sectional shape or size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple replaceable channels are provided in the bar feeder to adapt to different bar shapes and dimensions, then the adaptability to handle various bar cross-sections is improved, but the device complexity increases and production time is lost during channel replacement
Solution Approach 1:
The invention employs a single universal channel design that can accommodate bars of various cross-sectional shapes (circular, hexagonal, square, rectangular) and dimensions through the action of movable support elements. These elements adapt their position and orientation based on the bar's geometry, eliminating the need for multiple specialized channels while maintaining full adaptability.
Solution Approach 2:
The channel incorporates movable support elements that can dynamically adjust their position, orientation, and spacing according to the specific bar being processed. This dynamic adaptation allows a single static channel structure to function as multiple specialized channels would, resolving the contradiction between universality and complexity.
2Device complexity
If a single channel is continuously used for dissimilarly-shaped bars, then the device complexity is reduced, but manufacturing precision deteriorates due to vibrations from increased eccentricities
Solution Approach 1:
The channel features localized adjustable support elements that can be independently positioned to provide optimal support at specific locations along the bar. This allows the single channel to maintain high precision for each specific bar type by concentrating support where needed, rather than requiring a perfectly fitted channel for each bar shape.
Solution Approach 2:
The support elements within the channel can change their positional parameters, spacing, and orientation based on the bar's dimensions and shape. This parameter adaptation minimizes eccentricities and vibrations for each specific bar type, maintaining manufacturing precision without requiring multiple fixed channels.
3Manufacturing precision
If the spindle rotation speed is reduced to limit vibrations when using a single channel, then manufacturing precision is improved, but productivity decreases
Solution Approach 1:
The support elements are pre-positioned or rapidly adjustable to optimal locations before the bar is inserted, minimizing eccentricities and vibrations from the start. This preliminary configuration allows the spindle to operate at high speeds without generating excessive vibrations, maintaining both precision and productivity.
4Ease of operation
If lubrication is applied to the channel to enable bar rotation, then ease of operation is improved, but loss of substance increases due to oil consumption and dispersion
Solution Approach 1:
The bar's own weight and the gravitational force create sufficient friction between the bar surface and channel to enable controlled rotation without external lubrication. The system uses the natural physical properties of the bar-channel interaction to achieve the required motion, eliminating oil consumption and environmental dispersion issues.
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 significantly reduces vibrations and eliminates the need for lubrication, enabling high-speed machining of bars with any shape or size, including non-circular ones, by providing a stable and adaptable gripping mechanism that maintains optimal alignment with the spindle axis.
Implementation Method 1
a linear fluid actuator (14), having a body (25) and a shaft (15), the shaft (15) being equipped with a piston (26), housed inside the cylindrical body (25), which defines bilateral chambers for the loading and unloading of an operating fluid
Implementation Method 2
said arms (13a, 13b) being held, in counterface to each another, by just as many conical surfaces (17a, 17b) which converge on the axis (3a) of the bar (3)
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A feeding apparatus (1) for feeding semi-finished products (2) which have an elongate shape along a feeding line (4) of a machine tool, comprising an elongate rod-shaped body (6) positioned longitudinally to the feeding line (4), supported by a first carriage (7) and a tubular body (8) positioned on the feeding line (4), supported by a second carriage (10), with said first and second carriages (7,10) being motor- driven, movable back and forth parallel to the feeding line (4); and control means (11) coordinating the movements of the carriages (7,10), thus allowing a semi-finished product (2) interposed between the rod-shaped body (6) and the tubular body (8) to penetrate the tubular body (8) and to be guided along it longitudinally to the line (4) due to the longitudinal action applied by the rod-shaped body (6). Said first carriage (7) comprises a motor-driven slide (17), translatable in a guide (19) in both directions along an axis (18) transversal to the feeding line (4), which supports said rod-shaped body (6) between a first end-of-stroke position wherein said rod-shaped body (6) is aligned along the feeding line (4), as the operating position, and a second end-of-stroke position wherein said rod-shaped body (6) is offset from the feeding line (4), as the non-operating position.