US2795942A - Dishware construction - Google Patents

Description

June 18; 1957 DAVID H. HARRIS BY fi T A ATTORNEYS I June 18, 1957 D. H. HARRIS 2,795,942

DISHWARE CONSTRUCTICN INVENTOR. FIG.4 DAVID H. HARRIS lam +Jm United States Patent DISHWARE CONSTRUCTION David H. Harris, New Castle, Pa., assiguor to Shenango China, Inc., New Castle, Pa., a corporation of Pennsylvania Application January 7, 1955, Serial No. 480,380 3 Claims. (CI. 65-15) This invention relates to plates, saucers and similar dishware having a fiat well or central portion surrounded by a gently upwardly sloping rim portion extending circumferentially around the fiat central portion. The invention is particularly adapted to ware which is manufactured from conventional ceramic materials which in their final form are relatively frangible and comprise a bisque body with a glaze layer applied on its outer surface.

In all commercial food service operations where great numbers of pieces of ceramic dishware are repeatedly handled, ware replacement is a substantial cost factor. Replacement is necessitated not only by ware breakage, but also by starringfracturing of the glaze generally occurring in the center portion or well of the ware. Such fractured glaze quickly becomes disclored with dirt and waste matter, rendering the ware unsanitary and unsightly and requiring its replacement.

Starring occurs at only a fraction of .the value of impact which causes breakage, impact being measured in terms of distance through which a steel ball of standard weight falls against the ware. For conventional eight-inch diameter ware, starring occurs at 40% or less of the value of impact which causes breakage when measured by the above standard testing procedure which is specified in current Specification M. C. 30l of Army Ordnance for testing chinaware. Usually, starring occurs at less than a third of the value of impact which causes breakage.

Breakage may be somewhat reduced by providing plates having a relatively thick depth of section, although such plates are frequently unacceptable from an aesthetic point of view and also because of their excess weight. However, with even the sturdiest and heaviest ware, starring still occurs at only a fraction of the impact value at which breakage occurs. In this respect, increase in starring resistance is critical, being of greater importance than increase in breakage resistance.

The present invention embodies the discovery that the disproportion between starring incidence and breakage incidence can be almost eliminated by the provision of a central disc-like protuberance on the well bottom. Ware weight is increased slightly by this protuberance, and ware well strength and breakage strength are proportionately slightly increased in the central area. Surprisingly, however, the impact value at which starring occurs (the critical value for replacement purposes) is increased to the point where it approaches breaking strength, so that the disproportion between starring incidence and breakage incidence is almost eliminated.

The disc-like reinforcing member contemplated by my invention, located as it is within the foot of the ware, is invisible from any angle when the ware is placed in a table setting. The ware neither appears heavier nor handles difierently than conventional ware of equivalent general shape. The structural modifications involved in my invention therefore involve no objectionable features whatsoever from the aesthetic standpoint.

These advantages of my invention will be more fully 2,795,942 Patented June 18, 1957 'Figures 1 and 2, a main central portion or well 10 is sur:

rounded by a conventional annular rim portion 11. The underside of the central portion 10 is shaped to include the usual pedestal rib or foot 12.

A disc-like protuberance 13 is included on the underside of the central portion 10. The protuberance 13 is preferably concentric with the Ware piece. The protuberance 13 is formed from the single mass of frangible material of which the illustrated dishware piece consists. As will be apparent to those familiar with dishware manufacture, there is a negligible dilterence between the cost of shaping dishware including protuberances 13 and the cost of shaping dishware that does not include such members. The protuberance 13 may be considerably shallower than the foot rib 12. In the particular piece illustrated, which is typical of numerous pieces of eightinch diameter pieces which have been made and tested, the thickness through the majority of the well 10 is about .237 inch, and the thickness through the protuberance 13 is about .308 inch.

To eliminate any crevices or abrupt inside corners which would tend to accumulate dirt or food particles, it it preferable that the periphery of the protuberance 13 is faired off into the bottom surface of the center portion or well 10, the protuberance 13 being reversely curved from its point of maximum height to its foot to effect a smooth merger with the underside of the ware. This construction also eliminates the danger of high local stress and structural fatigue which might result from the provision of an abrupt angle at the root of the protuberance 13.

As previously stated, the construction described above, by its reinforcing efiect, slightly increases breakage strength of the ware. The lower and therefore far more critical starring resistance of the ware is, however, greatly increased to almost equal breakage strength. Thus, the modification of conventional ware contemplated by my invention, without any aesthetic compromise and at insignificant cost, greatly increases average service life.

A modified form of my invention is shown in Figures 3 and 4. The illustrated piece comprises a main central portion or well 20 surrounded by a conventional annular rim portion 21. The underside of the central portion 20 is shaped to include the usual pedestal rib or foot 22.

A protuberance 23 is included on the underside of the central portion 20. The protuberance 23 is generally similar to the disc-like protuberance 13 with the exception that formed therein are annular lightening grooves 24. The shoulders and roots of these grooves are preferably rounded to prevent entrapment of food waste or dirt and to avoid the sharp angles which might cause high local stresses and structural fatigue. The results achieved with the modification of Figures 3 and 4 are comparable to those achieved with the modification of Figures 1 and 2.

Embodiments of my invention other than those specifically described herein will suggest themselves. My invention is not limited to the precise details of the disclosed embodiments but is defined by the scope of the following claims:

What is claimed is:

1. A dishware piece comprising a unitary mass "of frangible material comprising a fired bisque body with a. glaze layer fired on the outer surface thereof, said body having a substantially flat; circular central portion surrounded by a gently upwardly sloping radially outwardly extending circular rim portion terminating in a peripheral edge, a foot rib extending around said central portion and downwardly from the bottom surface of said central portion to a lower bounding plane, a disc-shaped protuberance on the bottom surface of said central portion, a plurality of concentric lightening grooves formed in the bottom of said protuberance, said protuberance having together with the section of said central portion from which it depends a total depth of section substantially greater than the normal thickness of said central section, but not greater than the depth of the foot rib.

2. A dishware piece comprising a unitary mass of frangible material comprising a fired bisque body with a glaze layer fired on the outer surface thereof, said body having a substantially flat circular central portion surrounded by a gently upwardly sloping radially outwardly extending circular rim portion terminating in a peripheral edge, a foot rib extending around said central portion and downwardly from the bottom surface of said central portion to a lower bounding plane, a disc-shaped protuberance-on the bottom surface of said central portion, the periphery of said protuberance being faired off into said bottom surface of said central portion, a plurality of concentric lightening grooves formed in the bottom of said protuberance, the roots of said groove and the shoulders defined by said grooves comprising smoothly curved surfaces, said protuberances having together with the section of said central portion from which it depends a total depth of section substantially greater than the nor- 4 c mal thickness of said central section, but not greater than the depth of the foot rib.

3. A dishware piece comprising a unitary mass of frangible material comprising a fired bisque body with a glaze layer fired on the outer surface thereof, said body having a substantially fiat circular central portion surrounded by a gently upwardly sloping radially outwardly extending circular rim portion terminating in a peripheral edge, a foot rib extendingaround said central portion and downwardly from the bottom surface of said central portion to a lower bounding plane, adisc-shaped protuberance on the bottom surface of said central portion, the periphery of said protuberance being faired off into said bottom surface'of said central portion, said protuberance having together with the section of said central portion from which it depends a total depth of sectional thickness substantially greater than :the thickness of said central section but not greater than the total depth of sectional thickness at said foot rib.

References Cited in the file of this patent UNITED STATES PATENTS D. 137,118 Kleinberg Jan. 25, 1944 117,766 Gibson Aug. 8, 1871 1,666,389 Mander Apr. 17, 1928 1,979,911 Steudel Nov. 6, 1934 2,561,594 Pokras -s July 24, 1951 2,589,967 Sawyer Mar. 18, 1952 2,690,065 Harman et al Sept. 28, 1954 FOREIGN PATENTS 11,953 Great Britain Aug. 11, 1888 525,264 Great Britain Aug. 26, 1940 1,028,652 France Feb. 25, 1953

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