Hydraulic Clamping Device with Nested Presetting Screw
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Solution Overview
Problem
Hydraulic clamping devices are complex and difficult to use accurately for repeated clamping after tool changes due to even force distribution across both expansion sleeves, and existing solutions require actuation from different sides and can lead to incorrect tensioning if screws are actuated in the wrong order.
Innovation Solution
A clamping device with a central through-hole in the clamping screw for a presetting screw, allowing two defined pressures to be set in the pressure chamber by moving the presetting screw into a presetting position and then the clamping screw into its actuation position, enabling separate and defined fluid pressure increases for precise clamping.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single clamping screw is used to actuate both expansion sleeves simultaneously, then the device structure is simple, but exact repeated clamping is hardly possible after tool change due to even force distribution
Solution Approach 1:
The single clamping screw is segmented into two separate actuating elements: a clamping screw for external clamping and a presetting screw for internal clamping. This segmentation allows independent adjustment of clamping forces, enabling precise repeated clamping while maintaining structural simplicity.
Solution Approach 2:
The presetting screw performs preliminary internal clamping before the main clamping screw applies external clamping force. This preliminary action ensures that the tool holder is properly positioned and secured internally before final external fixation, improving overall clamping precision.
2Manufacturing precision
If two clamping screws are used to actuate expansion sleeves sequentially from different sides, then clamping precision is improved, but the device becomes more complex and difficult to operate
Solution Approach 1:
Both the clamping screw and presetting screw are merged into a single accessible location on the tool holder, allowing both actuating elements to be operated from the same side. This combining maintains precise sequential clamping capability while significantly improving ease of operation.
Solution Approach 2:
The presetting screw is nested within the clamping screw structure, with the presetting screw positioned inside the hollow clamping screw. This nested arrangement allows both screws to be accessed and operated from the same side, simplifying operation while maintaining precise sequential clamping.
3Manufacturing precision
If two clamping screws are used without proper control, then clamping precision can be improved, but incorrect tensioning occurs if screws are actuated in the wrong order
Solution Approach 1:
The presetting screw is designed to perform preliminary internal clamping before the main clamping screw applies external force. The presetting screw has a limited travel range that prevents it from fully actuating the expansion sleeves, ensuring it only performs the preliminary internal clamping function in the correct sequence.
Solution Approach 2:
The two actuating elements have different local characteristics: the presetting screw has a shorter effective travel and acts on the inner expansion sleeve, while the clamping screw has longer travel and acts on the outer expansion sleeve. These differentiated local qualities ensure correct sequential operation and prevent incorrect tensioning.
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 allows for precise and safe clamping of tools with defined deformation of expansion sleeves, enabling easy operation and retrofitting of existing devices, ensuring correct actuation and preventing incorrect tensioning.
Implementation Method 1
the piston can be displaced inwards by turning the clamping screw while increasing the pressure in the pressure chamber
Implementation Method 2
the expansion sleeves are simultaneously elastically deformed to more or less synchronously move the tool holder through the radially outward deformation of the outer expansion sleeve
Data Source
Figure 1~2
Figure 3~4
AI summary
The clamping device has a clamping screw (7) with a threaded central through boring (9), into which a pre-setting screw (10) is screwed. The pre-setting screw can be moved axially inward into a pre-setting position relative to the clamping screw. It can be moved out of the clamping screw against the piston (8) to press it inward to raise the pressure in the chamber.