Manually Operated Chuck Centring Device for Workpiece Alignment
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Solution Overview
Problem
Manually operated chucks for machine tools struggle to precisely center rotationally symmetrical workpieces due to manufacturing tolerances between components, leading to inaccuracies and unreliable clamping of heavy and large workpieces during machining.
Innovation Solution
Incorporation of a centring device that applies a radially acting force to compensate for manufacturing play and error tolerances, allowing precise centring and continuous adjustment of the workpiece's position relative to the chuck's axis, even during machining, using a combination of wedge bars, driving rings, and threaded spindles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If standard manufacturing tolerances are used for chuck components, then production cost is reduced, but workpiece centering precision deteriorates due to accumulated play between components
Solution Approach 1:
A centring device is introduced as an intermediary component between the workpiece and the clamping jaws. This device compensates for the accumulated play and tolerance errors in the driving ring, wedge bars, and threaded spindle by providing a positive centring action that pushes the workpiece into correct alignment, thereby maintaining high centering precision without requiring expensive tight-tolerance components
Solution Approach 2:
The centring device performs preliminary centring of the workpiece before the clamping jaws apply full clamping force. By establishing correct workpiece position in advance, the system prevents the development of clamping errors during machining, even when using components with standard manufacturing tolerances
2Force
If clamping force is increased to hold heavy workpieces, then workpiece security is improved, but workpiece centering deteriorates due to magnification of component play
Solution Approach 1:
The centring device provides beforehand cushioning by maintaining continuous contact with the workpiece and compensating for play in the clamping mechanism. This preliminary centring action ensures that even when high clamping forces are applied to heavy workpieces, the workpiece remains accurately centered because the centring device has already established the correct position and compensates for any play that develops under load
3Device complexity
If three clamping jaws are used to reduce device complexity, then chuck structure is simplified, but reliable clamping of heavy workpieces deteriorates due to insufficient support
Solution Approach 1:
The centring device serves multiple functions: it provides positive centring of the workpiece, acts as an additional support point for heavy workpieces, and compensates for play in the clamping mechanism. By adding this multi-functional device, the chuck can reliably clamp heavy workpieces without increasing the number of clamping jaws, thus maintaining structural simplicity while improving reliability
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 precise central positioning of workpieces throughout machining, maintaining reliable clamping and reducing machining inaccuracies by compensating for manufacturing tolerances and weight changes, eliminating the need for frequent repositioning and reclamping.
Implementation Method 1
Two of the three clamping jaws are directly driveably connected to the driving ring by means of a wedge bar, and are moved linearly in the base body between the particular wedge bar and the clamping jaw due to the helical gearing
Implementation Method 2
The driving ring is in a shape-locking or drivable connection with a threaded spindle inserted in the base body
Data Source
AI summary
A manually operated chuck for machining of rotationally symmetrical workpieces, the chuck comprising: a base body, attached to clamping jaws radially movable on the base body for securing the workpiece and in which an opening extends at right angles to a longitudinal axis of the base body; a threaded spindle movably mounted in the opening and accessed from outside to change the position, thereof; a wedge bar in the base body proximate the spindle, the wedge bar being connected to the spindle and a clamping jaw in a shape-locking arrangement; a driving ring rotationally mounted in the base body and connected to the threaded spindle and to one of the wedge bars with play between the threaded spindle and driving ring, and/or the threaded spindle and a wedge bar, and/or between the driving ring and wedge bars of the clamping jaws, the workpiece disposed concentrically to a longitudinal axis of the chuck.