US Patent: 2,669,458
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| Chuck
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Patentee:
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| Ernest H. Johnson (exact or similar names) - Bridgeport, Fairfield County, CT |
| Assignees: |
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Bullard Co. - Bridgeport, Fairfield County, CT |
| Manufacturer: |
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Bullard Co. - Bridgeport, Fairfield County, CT |
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Patent Dates:
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| Applied: |
Apr. 19, 1952 |
| Granted: |
Feb. 16, 1954 |
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Joel Havens
Vintage Machinery entry for Bullard Machine Tool Co.
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Description: |
| Claims:
All chucks have inherent inaccuracies in that manufacturing tolerances for machining the jaw ways results in the center lines of the jaw ways intersecting at points other than the true center of rotation of the chuck spindle.
Cylindrical work to be properly gripped by a set of chuck top-jaws requires two fundamental conditions to be met, namely, the work-engaging surfaces of the top-jaw inserts must be absolutely concentric with the center of rotation of the work-rotating spindle, and the radial distance of the work-engaging surface of the top-jaw inserts must be identical.
These two fundamental requirements have led to the fabrication of top-jaw inserts by a method that requires final turning and/or grinding of the work-engaging surfaces thereof while the top-jaws are attached to the work-supporting spindle with which they ultimately, are to be employed. The attending disadvantages of top- jaw inserts made by such a method are manifest. Down time for replacing top-jaw inserts is harmful to production schedules and particularly so in those cases where multiple spindle machines are concerned; interchangeability of top-jaws is impossible because only the inserts of top-jaws for a given spindle are accurate enough for that spindle; damage to any one top-jaw insert requires as much down time to replace it as would be required to replace an entire set of top-jaw inserts; and accuracy in chucking is limited because variations in chucking pressures causes unpredictable stress and strain variations in the links of the chuck-jaw actuating mechanism resulting in material run out during a turning operation, which requires resurfacing the inserts for every substantial change in chucking pressures.
The principal object of this invention is to provide a chuck-jaw assembly including a completely prefabricated top-jaw insert that is at all times interchangeable with comparable inserts employed with top-jaws for any work-supporting spindle.
Other objects include the provision of a top- jaw insert adapted to be adjusted radially, as well as angularly, relatively to the top-jaw to which it is attached; the provision of such a top- jaw insert which can be adjusted relatively to its supporting top-jaw to compensate for unpredictable strains and stresses in the jaw-actuating linkage; and the provision of a chuck-jaw construction in which a radially-movable lower jaw supports a top-jaw that in turn supports a top- jaw insert for movement along the longitudinal axis of the lower jaw, as well as for pivotal movement about a point located along said axis.
Other objects include the provision of such a, top-jaw in which an insert is, capable of being adjustably mounted for maintaining-its prefabricated work-engaging surface in perfect concentricity with the axis of rotation of the work- supporting spindle with which it is employed; the provision of such a top-jaw and insert therefor that employs a single mounting member to provide pivotal adjustment, of the insert about a point and radial adjustment relatively to the axis of rotation of the spindle with which such- top-jaw and insert are to be employed. |
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