Four-Jaw Collet Chuck With Rocker Compensation and Low Profile
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Solution Overview
Problem
Existing chucks for machine tools face inaccuracies in workpiece positioning due to mechanical overdetermination and tolerance deviations, leading to machining errors, and require significant installation space for drive devices, which is often not available in machine tool working areas.
Innovation Solution
The chuck design features linearly movable piston rods or threaded spindles perpendicular to the centering axis, allowing for synchronous radial movement of clamping jaws and compensating movements via rockers, ensuring all clamping jaws engage the workpiece simultaneously, with a synchronizing ring coordinating actuating forces and speeds, and a compact overall height.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If drive devices are aligned coaxially with the longitudinal axis of the chuck body, then synchronous radial movement of clamping jaws is achieved, but considerable installation space is required which is not available in machine tool working areas
Solution Approach 1:
The drive devices are reoriented from axial alignment (parallel to centering axis) to radial alignment (perpendicular to centering axis). This dimensional change allows the piston rods to move radially outward to directly drive the clamping jaws, eliminating the need for lengthy axial drive mechanisms and reducing the overall height of the chuck while maintaining synchronous clamping capability
2Adaptability or versatility
If movement clearance is provided to compensate for different distances between pairs of diametrically opposed clamping jaws, then workpieces with rectangular contours can be clamped, but significant inaccuracies in clamping positions arise leading to machining errors
Solution Approach 1:
The rocker arms are introduced as dynamic compensating mechanisms that can pivot to accommodate variations in workpiece geometry. When one pair of clamping jaws contacts the workpiece earlier than the other pair, the rocker arms rotate to absorb the differential movement, allowing all four jaws to reach their clamping positions simultaneously without requiring excessive movement clearance, thereby maintaining high positioning accuracy while accommodating rectangular workpieces
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
This design achieves precise, repeatable workpiece alignment coaxial with the machine tool's centering axis, reduces machining errors, and minimizes installation space requirements by redirecting axial movements into radial clamping actions, ensuring consistent clamping force and efficient use of available space.
Implementation Method 1
The axial movements of the driver and the coupling part create a radially directed feed movement for the clamping jaws, as these are connected to the driver and movably mounted in a guide groove
Implementation Method 2
a rocker and a driver are provided between the base jaws and a mechanically actuated drive unit, each of which is drivingly connected to one of the rockers
Implementation Method 3
the clamping jaws, as these are connected to the driver and movably mounted in a guide groove
Data Source
Figure 1
Figure 2a
Figure 2b
AI summary
In a chuck (1) by which workpieces (2) are individually supported for machining by a machine tool (3) and aligned coaxially to a centering axis (4), which serves as a reference point for the machining of the workpiece (2) by the machine tool (3), with a chuck body (5) with at least four clamping jaws (6, 7, 8, 9) radially movably mounted on the chuck body (5), which are arranged in pairs in an X or Y axis and by which the workpiece (2) is aligned with the centering axis (4) and held during the machining process, and with a linearly movable pull piston (45) mounted in or on the chuck body (5), which is drivenly coupled to the respective clamping jaw (6, 7, 8, 9) such that the clamping jaws (6, 7, 8, 9) move radially in the direction of the workpiece to be clamped during the linear movement of the pull piston (45). (2) are delivered synchronously or are moved away from it,The pull piston (45) is arranged coaxially to the centering axis (4) inside the chuck body (5) and can be axially actuated by one or more drive units (12, 13, 52, 53). The aim is twofold: firstly, to compensate for the compensating movements between two adjacent and mutually perpendicular clamping jaws (6, 7, 8, 9) independently of their feed movement and contact with the workpiece (2) to be clamped; and secondly, to minimize the overall height of such a chuck (1). This is achieved by providing each drive unit (12, 13, 52, 53) with a linearly movable piston rod (26) or threaded spindle (55), the respective longitudinal axis (26' or 55') of which is arranged perpendicular to the centering axis (4).