Chuck Locking Device Expander Race Profile
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Solution Overview
Problem
The existing chuck locking devices for machine tools are prone to improper operation due to inappropriate assembly, maintenance, or unauthorized interventions, which can lead to uncontrolled release of preloaded springs, causing potential injury, and lack a mechanical stop to prevent the expander from sliding past the balls, and are vulnerable to Seeger ring breakage or detachment.
Innovation Solution
The expander races have a longitudinal profile with an increasing slope beyond the minimum working position, providing a mechanical end stop to prevent balls from leaving their races, and the stationary member includes a proximal abutment surface to act as an additional stop in case of Seeger ring failure, enhancing safety and preventing the mobile member and expander from escaping.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the expander races have a continuously decreasing slope profile allowing balls to leave at the distal end, then the device can achieve maximum radial displacement and locking position, but the expander may be released from its seat under spring action causing uncontrolled movement and potential injury
Solution Approach 1:
The race profile is designed with an increasing slope section at the distal end before the balls leave the race. This preliminary geometric feature creates a mechanical barrier that prevents the expander from being released by spring force, while still allowing the balls to achieve maximum radial displacement for locking when properly operated.
Solution Approach 2:
The race profile utilizes curved surfaces with varying slopes - a decreasing slope section for ball engagement and radial displacement, followed by an increasing slope section that acts as a mechanical stop. This curvature design allows the balls to roll smoothly during normal operation while preventing reverse movement that could release the expander.
2Stability of the object's composition
If the Seeger ring is used as a retainer for the mobile member and balls, then the device can maintain proper assembly, but the ring may break or detach under external forces leading to escape of components
Solution Approach 1:
A proximal abutment surface is incorporated into the stationary member to provide a mechanical stop for the balls in the minimum working position. This preliminary structural feature ensures that even if the Seeger ring fails, the balls cannot escape, thereby preventing mobile member and expander ejection.
Solution Approach 2:
The proximal abutment surface acts as a backup safety feature that cushions against the worst-case scenario of Seeger ring failure. By providing this redundant mechanical barrier beforehand, the design protects against component escape without requiring the operator to detect or respond to ring degradation.
3Reliability
If the expander can slide on balls and wear makes pressure locking ineffective, then the device may lose locking capability, but the increasing slope profile prevents further movement and maintains safety
Solution Approach 1:
The increasing slope section of the race profile creates a geometric mechanical stop that is independent of the pressure locking mechanism. Even when wear reduces the effectiveness of ball-to-abutment surface pressure locking, the increasing slope physically prevents the expander from moving further, maintaining safety through geometric constraint rather than friction or pressure.
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 ensures the expander remains securely seated, preventing uncontrolled movement and enhancing safety by providing a mechanical stop that prevents the expander from exiting its seat and additional protection against Seeger ring breakage or detachment, ensuring safe operation even without the ring.
Implementation Method 1
The device is driven into the locking position by a preloaded spring system, a main spring 7 and a secondary spring 8
Implementation Method 2
a preloaded spring system, a main spring 7 and a secondary spring 8
Implementation Method 3
the unlocking is carried out by a hydraulic system that overcomes the force of the springs
Implementation Method 4
the races formed in the outer surface of expander 3, along which balls 4 roll
Implementation Method 5
an expander 3 axially slidable within said mobile member 1 and suitable to push three wedging bodies 4 (usually balls) radially outwards against an abutment surface 5 of said stationary member 2
Data Source
Figure 1~2
Figure 3
AI summary
A chuck locking device for machine tools includes an axially mobile member (1) slidable within an axially stationary member (2), as well as an expander (3) axially slidable within the mobile member (1) and suitable to push three balls (4) radially outwards against a distal abutment surface (5) of the stationary member (2) through proper apertures (6) formed in the mobile member (1). The balls (4) roll along races, formed on the external surface of the expander (3), that have a decreasing slope from their proximal end towards their distal end up to the point of contact with the balls (4) which corresponds to the minimum working position of the device, and in the terminal distal length (16) of the races beyond said point of contact the slope increases up to their distal end so as to obtain a closed profile of the expander (3) suitable to prevent the balls (4) from leaving through its distal end.