Molding apparatus and method

A method of making a self-supporting body from a particulate material, comprising the steps of:

• a. placing a first batch of such material in a particulate chamber having opposed first and second wall means, said second wall means being advancable and retractable toward and away from said first wall means, and said second wall means having a high force section generally adjacent the center of said chamber, two low force sections adjacent respective ends of said chamber, and two intermediate force sections each located between the high force section and a respective one of the low force sections;
• b. simultaneously applying a relatively high force per unit area to said high force section of said second wall means applying lower forces per unit area to the low force sections of said second wall means, and applying to said intermediate force sections of said second wall means forces per unit area which are intermediate that of the high force section and those of the respective adjacent low force sections to advance said second wall means toward said fist wall means, so as to form a self-supporting body of said particulate material, tightly compressed adjacent the center and incrementally more lightly compressed toward the ends;
• c. retracting said second wall means from said first wall means to form a space between said first batch of said material and said second wall means;
• d. after so retracting said second wall means, displacing said self-supporting body with respect to said particulate chamber so that the lightly compressed portions adjacent one end are aligned with said high force section of said second wall means;
• e. placing a second batch of said material in said space;
• and
• f. again applying such relatively high force per unit area to said high force section of said second wall means to advance said second wall means toward said first wall means and more tightly compress said lightly compressed portions of said first batch of material along with a portion of said second batch of material while simultaneously applying such lower forces per unit area to said low force sections of said second wall means and applying such intermediate forces per unit area to said intermediate force sections.

A method of making a self-supporting body of particulate material, comprising the steps of:

• a. in a particulate chamber having opposed first and second wall means, said second wall means being advancable and retractable toward and away from said first wall means, emplacing a chamber-reducing member over one of said wall means:
• b. placing a first batch of such material in said particulate chamber;
• c. applying a force to said second wall means to advance said second wall means toward said first wall means and compress at least a portion of said first batch of material between said chamber-reducing member and the other of said wall means;
• d. retracting said second wall means;
• e. removing said chamber-reducing member;
• f. placing a second batch of said material in said particulate chamber between said first batch of material and said one wall means;
• and
• g. re-advancing said second wall means to compress said second batch of material.

A method of making tubular self-supporting bodies of different diameters but otherwise similar inner and outer surface configurations comprising the steps of:

• a. in an annular particulate chamber having opposed, inner and outer annular wall means, said outer wall means being advanceable and retractable toward and away from said inner wall means, emplacing a chamber-reducing member over one of said wall means to define a chamber-limiting surface parallel to but spaced from said one wall means;
• b. placing a first batch of such material in said particulate chamber;
• c. applying a force to said outer wall means to advance said outer wall means toward said inner wall means and compress said first batch of material between said chamber-reducing body and the other of said wall means to form a first self-supporting body;
• d. retracting said outer wall means;
• e. removing said first self-supporting body;
• f. removing said chamber-reducing member;
• g. placing a second batch of such material in said particulate chamber;
• and
• h. re-advancing said outer wall means to compress said second batch of material and form a second self-supporting body, having at least one diameter differing from the corresponding diameter of said first self-supporting body.

A mold for particulates comprising:

• opposed first and second wall means defining a particulate chamber therebetween, said second wall means being advancable and retractable toward and away from said first wall means;
• means for applying a force to said second wall means to advance said second wall means toward said first wall means;
• and
• a plurality of chamber-reducing members removably mountable over each of said wall means and each having a configuration, on the side opposite the respective wall means, which generally parallels said respective wall means.