Multi-Spindle Screw Machine Lubrication System
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Solution Overview
Problem
Existing lubrication systems for multi-spindle screw machines, such as the Davenport® five-spindle automatic screw machine, face issues like reduced effective bearing surface area, significant lubricant leakage, inadequate lubrication at lower spindle positions, and unnecessary continuous lubrication during head rotation, leading to inefficiencies and 'dry spindle' conditions.
Innovation Solution
A lubrication system with strategically configured body and head passageways that allow lubricant flow only when the head is at specific index positions, minimizing leakage paths and maintaining bearing surface area, and incorporating seals and pressurized ball bearing cavities to facilitate efficient lubricant distribution and chip clearance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an annular lubrication groove is machined into the head from the bearing surface, then lubrication is provided to the spindles, but the effective bearing surface area is reduced by approximately 25%
Solution Approach 1:
The continuous annular lubrication groove is segmented into discrete lubrication holes positioned at specific angular locations corresponding to spindle positions. This segmentation eliminates the need for a continuous groove, preserving the bearing surface area while still providing effective lubrication to each spindle when aligned with its respective hole.
Solution Approach 2:
Instead of providing lubrication uniformly across the entire bearing surface through an annular groove, the system provides localized lubrication through discrete holes positioned only where needed - at the angular positions where spindles are located. This local quality approach maintains bearing surface integrity while delivering lubrication precisely where required.
2Reliability
If a continuous annular lubrication groove is provided, then all spindles are lubricated continuously, but the lubricant leakage path length increases to approximately 55 inches
Solution Approach 1:
The continuous annular groove is divided into discrete, separated lubrication holes. This segmentation breaks the continuous leakage path into multiple short segments, reducing the total effective leakage path length and minimizing lubricant loss while still maintaining continuous lubrication supply to all spindles during rotation.
Solution Approach 2:
The system uses periodic lubrication delivery where each spindle receives lubricant in periodic pulses as the head rotates, rather than continuous lubrication through a groove. The discrete holes are positioned to deliver lubricant at the appropriate periodic intervals for each spindle position, achieving effective lubrication with minimal leakage.
3Reliability
If continuous lubrication is provided during head rotation, then all spindles are lubricated at all positions, but this is unnecessary since head rotation between index positions occurs in a fraction of a second
Solution Approach 1:
The lubrication system is designed to provide periodic lubrication pulses to each spindle when the head is at index positions, rather than continuous lubrication during rotation. The discrete holes are positioned and sized to deliver adequate lubricant during the brief periods when spindles are stationary at index positions, eliminating the need for complex continuous lubrication systems during rapid head rotation.
Solution Approach 2:
The lubrication holes are positioned and dimensioned to deliver the necessary lubricant quantity in advance during the index position dwell time, preparing the spindles with sufficient lubricant film before the rapid rotation occurs. This preliminary lubrication action eliminates the need for continuous lubrication during the fraction-of-a-second rotation between index positions.
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 system reduces lubricant leakage by 93%, maintains effective bearing surface area, ensures adequate lubrication at critical spindle positions, and effectively flushes chips from the work zone, enhancing machining efficiency and reducing wear.
Implementation Method 1
a source of pressurized lubricant. The improvement comprises: a body passageway communicating the source with the body bearing surface
Implementation Method 2
the body and head having closely-spaced and facing bearing surfaces... lubricant may flow from the source to the spindle
Implementation Method 3
incorporating seals and pressurized ball bearing cavities to facilitate efficient lubricant distribution and chip clearance
Data Source
AI summary
An automatic screw machine (20) has a body (22), and a head (21) that is rotatably mounted on the body and that is adapted to be selectively rotated relative to the body between any of a plurality of index positions. The body and head have closely-spaced and facing bearing surfaces (25, 28 and 26, 29), have spindles (23) journalled on the head for rotation relative thereto, and have a source of pressurized lubricant. The improvement broadly includes: at least one body passageway (32) communicating the source with the body bearing surface, the intersection of each body passageway with the body bearing surface defining a body port (33); a head passageway (36) communicating the head bearing surface with the spindle, the intersection of said head passageway with said head bearing surface defining at least one head port (42); and the body and head passageways being so configured and arranged such that lubricant may flow from the source to the spindle only when the head is in the vicinity of the index position such that the body and head ports overlap one another.