Tool Holder with Combined Mechanical and Hydraulic Chucking
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Solution Overview
Problem
Conventional tool holders, including mechanical and hydraulic chucks, face challenges in achieving sufficient retention stability and run-out accuracy due to limitations in holding area and interference, which restricts the improvement of holding strength and accuracy, especially in heavy and high-precision cutting applications.
Innovation Solution
A tool holder design that combines a mechanical chuck with a hydraulic chuck, featuring a cylindrical grip tube, a pressure ring, a nut, and a secondary grip portion with a pressure chamber, allowing for simultaneous radial compression and hydraulic pressure application to enhance holding strength and accuracy through increased surface contact and distance between holding points.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of moving object
If the chuck cylinder is made longer to increase the tool holding area, then the holding strength and run-out accuracy improve, but the rotational resistance of the nut increases making it difficult to turn
Solution Approach 1:
The tool holder is divided into two independent chuck systems: a mechanical chuck (first chuck) with a grip tube and a hydraulic chuck (second chuck) with a sleeve. Each chuck has its own holding mechanism and can operate independently, allowing the tool to be held at multiple positions without increasing the length of a single chuck cylinder.
Solution Approach 2:
The patent combines both mechanical chucking (via the grip tube) and hydraulic chucking (via the sleeve) in a single tool holder. This merging of two different chucking mechanisms allows the system to achieve the benefits of both: the mechanical chuck provides immediate gripping action while the hydraulic chuck provides adjustable, high-force holding, thereby increasing the effective tool holding area without the drawbacks of a single extended chuck cylinder.
2Strength
If a larger holding area is achieved by increasing chuck cylinder length, then holding strength improves, but the device complexity and rotational resistance increase
Solution Approach 1:
The holding function is segmented into two separate chucks: the mechanical chuck with grip tube for initial holding and the hydraulic chuck with sleeve for enhanced holding strength. This segmentation allows each component to be optimized for its specific function without requiring one oversized component, thereby reducing overall structural complexity while maintaining high holding strength.
Solution Approach 2:
The patent introduces a hydraulic chuck mechanism using a sleeve, pressure chamber, and hydraulic fluid. This hydraulic system provides powerful and adjustable holding force with compact structure, avoiding the need for a long mechanical chuck cylinder. The hydraulic pressure can be controlled to provide precise holding strength without increasing mechanical complexity.
3Measurement precision
If expansion rooms are positioned far from the mouth portion to fluid-tightly seal them, then run-out accuracy improves, but the fastening at the mouth portion becomes insufficient
Solution Approach 1:
The tool holder uses two separate chucking zones: the mechanical chuck at the front (mouth portion) providing strong fastening, and the hydraulic chuck positioned rearward providing precise run-out control. This segmentation allows each zone to be optimized for its specific function without compromise.
Solution Approach 2:
By merging the mechanical chuck (grip tube) and hydraulic chuck (sleeve) into a single integrated tool holder, the system achieves both strong mouth portion fastening and accurate run-out control simultaneously. The mechanical chuck ensures secure fastening at the front, while the hydraulic chuck positioned behind provides precise axial and radial control for accurate run-out.
4Volume of moving object
If the sleeve thin-walled portions are used for holding, then the structure is compact, but the holding strength is insufficient due to linear contact
Solution Approach 1:
The patent combines the mechanical chuck (grip tube) and hydraulic chuck (sleeve) to provide dual holding mechanisms. The mechanical chuck provides immediate and powerful gripping force through radial compression, while the hydraulic chuck provides adjustable and distributed holding force. This combination compensates for the limited holding capability of the thin-walled sleeve portions while maintaining structural compactness.
Solution Approach 2:
The hydraulic chuck uses hydraulic pressure applied to the thin-walled portions of the sleeve to generate powerful and uniformly distributed holding force. The hydraulic fluid transmits pressure evenly across the sleeve inner surface, transforming the weak linear contact into a strong and stable holding mechanism while maintaining the compact sleeve structure.
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 combined mechanical and hydraulic chuck design provides improved retention stability and run-out accuracy by increasing the holding area and minimizing rotational resistance, effectively addressing the limitations of conventional tool holders.
Implementation Method 1
a pressure chamber (9) extending around the outer periphery of the sleeve (5)... hydraulic fluid sealed in the cylinder (10), communication channel (12), and pressure chamber (9)... hydraulic pressure is produced in the pressure chamber (9), and the thin-walled portion (5b) of the sleeve (5) is radially compressed
Implementation Method 2
a nut (4) coupled to the pressure ring (3) so as to be rotatable relative to the pressure ring (3) and kept in threaded engagement with an outer periphery of the trunk (2b)... By tightening the nut, the chuck cylinder is radially compressed
Implementation Method 3
a cylindrical grip tube (2a)... having a tapered outer peripheral surface (a2)... The pressure ring (3) is fitted around the tapered outer peripheral surface (a2) of the grip tube (2a) so as to be slidable in an axial direction
Data Source
AI summary
A tool holder includes a holder body having a trunk and a grip tube, a pressure ring fitted around the grip tube, a nut for axially moving the pressure ring, and a sleeve defining a pressure chamber around the outer periphery thereof. The trunk is formed with cylinders in which pistons are inserted respectively. The cylinders communicate with the pressure chamber through a communication channel. Hydraulic fluid is sealed in the cylinders, the communication channel and the pressure chamber. When the nut is rotated, the pressure ring is axially moved, thus radially compressing the grip tube. Simultaneously, the pistons are pushed into the respective cylinders, thus increasing the pressure in the pressure chamber. As a result, both a first holding hole formed in the grip and a second holding hole formed in the sleeve decrease in diameter, so that a tool inserted in these holes are held in position.