The present invention relates to the field of three-dimensional prototype modeling. In particular, the present invention is a rapid prototyping system for forming three-dimensional objects of predetermined design by depositing multiple layers of a material in its fluid state from an extrusion head onto a base. The material is selected and its temperature is controlled so that it solidifies upon extrusion or dispensing onto the base, with the build-up of the multiple layers forming the desired object. In the present invention, three-dimensional objects are formed using filament supplied from a spool having an associated circuit for maintaining data regarding type and amount of filament on the spool.
A rapid prototyping system involves the making of three-dimensional objects based upon design data which is provided from a computer aided design (CAD) system. Examples of apparatus and methods for rapid prototyping of three-dimensional objects by depositing layers of solidifying material are described in Crump U.S. Pat. No. 5,121,329, Batchelder et al. U.S. Pat. No. 5,303,141, Crump U.S. Pat. No. 5,340,433, Batchelder U.S. Pat. No. 5,402,351, Batchelder U.S. Pat. No. 5,426,722, Crump et al. U.S. Pat. No. 5,503,785, and Abrams et al. U.S. Pat. No. 5,587,913, all of which are assigned to Stratasys, Inc. Rapid prototyping systems having a filament feed, or, alternatively, a solid rod feed, are described in the Crump '329 patent and the Crump '433 patent.
In a rapid prototyping system that uses a solid rod feed, rods or "wafers" of modeling material are typically stored in a cassette which dispenses the rods to the system, as described in co-pending application Ser. No. 08/556,583 which is now U.S. Pat. No. 5,764,521, assigned to Stratasys, Inc. In a rapid prototyping system that uses a filament feed, a length of filament wrapped around a filament spool supplies filament to the system.
In using either a filament feed or a solid rod feed, it is desirable for the control system of the rapid prototyping system to keep track of the amount of modeling material remaining in a cassette or on a spool. It is also desirable for the control system to know the type of modeling material that is on the cassette or spool, and the proper extrusion parameters for dispensing the material.
A rod dispensing cassette having an electronically readable and writeable memory device that provides data to the control system is described in co-pending application Ser. No. 08/556,583. The memory device is attached to the cassette so that electrical contact is made to the control system through a connector when the cassette is manually inserted. The memory device serves as an electronic tag which informs the control system of the type of material that is in the cassette, the proper extrusion parameters for dispensing the material, the current number of rods in the cassette, and the cassette serial number.