Zero-Point Clamping Mechanism With Rotary Actuation for Compact Fixturing
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Solution Overview
Problem
Existing zero-point clamping devices are bulky due to high structural requirements and manufacturing tolerances, limiting their use in space-constrained machine tools, and require excessive actuating forces, making them time-consuming and costly for workpiece exchange.
Innovation Solution
A zero-point clamping device with an actuating element featuring two counter-rotating threads with different pitches, drive pins, and pivot pins to achieve compact design and efficient clamping, allowing for quick and force-limited object exchange with minimal rotational input.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If axial feed movements of the actuating piston are supported in the housing, then the clamping device achieves reliable workpiece fixation, but the housing requires very high structural measurements, increasing its size
Solution Approach 1:
The patent transforms the actuation mechanism from axial linear movement to rotary movement. The actuating element rotates around the centering axis, and this rotational motion is converted to radial clamping movement through cam profiles. This dimensional change from axial to radial actuation allows compact housing design while maintaining reliable clamping.
Solution Approach 2:
The clamping slides are arranged radially around the centering axis, with each slide positioned at different angular positions. The drive segments are nested within the housing, rotating around the central axis. This radial nesting arrangement allows multiple clamping elements to be packed into a compact cylindrical housing volume.
2Device complexity
If the infeed path of the clamping slide is limited by inclined surfaces, then the clamping device structure is simplified, but the infeed path becomes extremely small, limiting clamping stroke
Solution Approach 1:
Instead of using inclined surfaces that convert axial movement to radial movement, the patent uses cam profiles with varying radial distances from the centering axis. The cam surfaces are positioned at different radial positions, allowing the clamping slides to achieve substantial radial infeed stroke through the rotational movement of the actuating element, thereby extending the infeed path without increasing axial height.
3Ease of operation
If the outer diameter of the housing is increased to provide radial movement space, then the clamping slides can move freely, but the housing becomes larger in both height and outer circumference
Solution Approach 1:
The patent eliminates the need for large radial clearance by changing the actuation from axial linear movement to rotary movement around the centering axis. The actuating element rotates within the housing, and the cam profiles are positioned to provide adequate clearance from the housing wall, allowing sufficient radial movement of clamping slides without increasing the housing outer diameter significantly.
Solution Approach 2:
The clamping mechanism components are arranged in a compact radial pattern around the centering axis. The drive segments, clamping slides, and cam profiles are nested within the housing in a concentric arrangement, maximizing space utilization and minimizing the required housing outer diameter while maintaining adequate clearance for radial movement.
4Volume of stationary object
If guide grooves and cams are used to convert rotary movement to radial feed, then the housing size is reduced, but manufacturing tolerances must be extremely small to prevent play
Solution Approach 1:
The clamping mechanism is divided into modular components: the actuating element with cam profiles, the drive segments with guide surfaces, and the clamping slides. Each component can be manufactured and assembled separately. The segmentation allows for accumulated tolerance compensation and simplifies the manufacturing of individual parts while maintaining overall precision through the modular assembly architecture.
5Force
If a large number of revolutions are required for clamping slide actuation, then the clamping process becomes time-consuming, but the actuating force can be controlled
Solution Approach 1:
The cam profiles are designed with varying radial distances from the centering axis, creating different mechanical advantage ratios during the rotation cycle. The cam geometry allows for rapid clamping action during portions of the rotation while maintaining force control. The dynamic variation in cam radius enables both fast workpiece exchange and controlled actuating forces within a single rotation cycle.
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 enables a compact, reliable, and repeatable clamping system that reduces manufacturing costs and actuating force requirements, allowing for rapid and efficient workpiece exchange with reduced external dimensions and improved manufacturing tolerances.
Implementation Method 1
two spaced-apart threads which have identical pitches and are designed to be inclined in opposite directions to one another, that a drive pin is inserted in each thread, which is in a driving operative connection with the respective thread in such a way that by means of the rotation of the actuating element, the drive pins can be moved along the axis of rotation of the actuating element
Implementation Method 2
between the two drive segments connected to the actuating element and the drive segment arranged adjacent thereto, in each case a pivot pin is provided to form a rotary joint
Data Source
Figure 1
Figure 2
Figure 3a
AI summary
A zero-point clamping device (1) for the centric and repeatable locking of an object (2), in particular a workpiece, a tool or a pallet, or a support part (3) to which the respective object (2) is attached, consists of: - a housing (4), - a receiving opening (5) incorporated in the housing (4) which has a centering axis (6) to which the axis of symmetry (2' or 3') of the object (2) or the support part (3) is coaxially aligned during the clamping process, - at least two clamping slides (7, 8 or 9) which are each axially displaceable in a bore (10) provided in the housing (4) and which open into the receiving opening (5) during the clamping state and thereby act on the object (2) or the support part (3) and fix it, and an actuating element (11) rotatably mounted in the housing (4) through which the clamping slides (7, 8, 9) are movable,The actuating element (11) has one axis of rotation (12) that is tangential and spaced apart from the receiving opening (5). This is intended to enable, firstly, a reliable, permanent, and repeatable fixation of a large number of workpieces, tools, pallets, or other objects (2), and secondly, to allow the housing (4) of the clamping device (1) to be extremely compact, meaning its external dimensions in height and diameter can be extremely small. This is achieved by incorporating two spaced-apart threads (13, 14) into the actuating element (11). Each thread (13, 14) has identical pitches and is inclined in opposite directions. Furthermore, a drive pin (15, 16) is inserted into each thread (13, 14), which is in a driving operative connection with the respective thread (13 or 14).that by means of the rotation of the actuating element (11) the drive pins (15, 16) are movable along the axis of rotation (12) of the actuating element (11), - that at least two drive segments (21, 22 or 23) are floatingly mounted in the housing (4), which extend in an arc around the centering axis (6) of the receiving opening (5), - that two of the drive segments (21, 22) are motiveally coupled to the actuating element (11) via one of the respective drive pins (15, 16), - that a pivot bolt (17, 18) is provided between the two drive segments (21, 22) connected to the actuating element (11) and the adjacent drive segment (21, 22 or 23) to form a pivot joint, - and that each clamping slide (7, 8, 9) is connected to one of the drive segments (21, 22, 23) is connected.