Plastic encased weights

#The invention generally relates to weights for weighing equipment employed in laboratories or for use in classrooms for teaching mass measurement as part of weighing exercises mathematics or science curricula. More particularly, this invention relates to inexpensive, optionally color coded weights made from plastic-encased high mass round rod that resist undesired rolling about or ingestion by children and can be stacked in engaged, end-to-end relation.

#Conventional, hexagonal, all-metal weights are cut from hexagon-shaped metal rod and stamped with appropriate weight markings. Such weights typically lack any matching recessed or protruding end portions for engaged or nested stacking in end-to-end relation with other such weights. Hence, if it is desired to arrange conventional weights in stacks for storage or to combine masses for use in weighing exercises, such conventional, flat all-metal weights tend to slide off one another.

#In addition, the hexagon-shaped steel rod material from which such conventional weights are cut tends to cost considerably more than comparable round steel rod material. Also, because the hexagon-shaped steel rod used in the conventional weights is exposed to the environment, the exterior of the weights is ordinarily plated, which further increases manufacturing costs. Furthermore, even plated weights are vulnerable to corrosion when scratched or subjected to extended exposure in corrosive laboratory conditions.

#For a more complete understanding of the present invention, reference is now made to the following description of the invention taken with the accompanying drawings, in which:

#FIG. 1 is a perspective view of a prior art all-metal, hexagonal weight;

#FIG. 2 is an exploded perspective view of a weight in accordance with the present invention and its component parts;

#While this invention is susceptible of embodiment in many forms, there is shown in the drawings, and will be described in detail herein, a preferred embodiment, with the understanding that the present disclosure is to be considered an example of the principles of the invention and is not intended to limit the invention to the embodiment illustrated.

#FIG. 1 shows a prior art hexagonal weight 10 formed from a steel rod having a substantially hexagonal transverse cross-section. The mass of the weight (100 g) is stamped on ends or faces 11 or 13 in a separate stamping operation after the weight is made. Faces 11 and 13 are substantially flat and lack any means for engaging or interlocking with another weight when placed in vertically stacked end-to-end relation.

#FIGS. 2-6 illustrate an encased weight 20 according to a preferred embodiment of the present invention. While only hexagon-shaped outer configurations are illustrated and described herein, pentagonal, circular, square or other outer configurations should be considered as being within the scope of the invention. The weight 20, as shown in FIG. 2, comprises a shell 22 having a body 30, end portions 23 and 24, and an interior cavity 25 along the longitudinal axis of the shell.