Use of tape-controlled milling machines to carve combustible casting patterns

Claim 2

As a new use for a preprogrammed milling machine which follows out automatically a previously devised program of instructions, the method of carving casting patterns from pattern material comprised of self-adhered beads of expanded polystyrene and whose density is less than 3 pounds per cubic foot, and which is combustible under a charge of molten metal, comprising the steps of providing the machine with a rotatable cutter having a cutting edge spaced radially from its axis and having the capacity to cut such material at more than five times the feasible depth of cut when machining steel, chucking in the machine a billet of such material whose size exceeds that of the casting pattern to be carved therefrom, feeding to the machine a previously devised program of instructions which provides such a linear feed rate and speed of cutter rotation as to achieve a rate of material removal at least 100 times as great as that for steel, and which directs movement of the cutting edge into the billet immediately to a position along a portion of the desired final contour, and thence directly along said final contour portion, and operating the machine to carve the billet at such rate of material removal according to the program, whereby to cut to contour those self-adhered beads along the desired final contour and simultaneously to remove the beads making up the material outwardly thereof.

Claim 3

As a new use for a preprogrammed milling machine, the method of carving a casting pattern from a pattern material which is combustible under a charge of molten metal and whose density is less than 3 pounds per cubic foot, comprising the steps of providing the machine with a rotatable cutter having a spindle axis of rotation and a cutting edge spaced radially outward therefrom, and having the capacity to cut such material at more than five times the feasible depth of cut when machining steel, chuckIng in the machine a billet of such combustible pattern material whose size exceeds that of the casting pattern to be carved therefrom, providing the machine with a carving program which provides such a linear feed rate and speed of cutter rotation as to achieve a rate of material removal at least 100 times as great as that for steel, and under which such cutter is directed immediately into the billet, through such excess size, to a point at which its said cutting edge reaches a final surface portion of the pattern to be carved, and under which program the cutter is then directed along such path that its cutting edge follows a portion of the final contour of the pattern, and then operating the machine to move said cutter according to said program, whereby the final surface portion of such pattern is provided without repetitive cuts regardless of the amount of excess billet material.

Claim 4

As a new use for a preprogrammed milling machine, the method of carving a casting pattern from a pattern material which is combustible under a charge of molten metal and whose density is less than 3 pounds per cubic foot, comprising the steps of providing the machine with a rotatable cutter having a spindle axis of rotation and a cutting edge spaced radially outward therefrom, and having the capacity to cut such material at more than five times the feasible depth of cut when machining steel, chuckIng in the machine a billet of such combustible pattern material whose size exceeds that of the casting pattern to be carved therefrom, providing the machine with a carving program which provides such a linear feed rate and speed of cutter rotation as to achieve a rate of material removal at least 100 times as great as that for steel, and under which such cutter is directed immediately into the billet, through such excess size, to a point at which its said cutting edge reaches a final surface portion of the pattern to be carved, and under which program the cutter is then directed along such path that its cutting edge follows a portion of the final contour of the pattern, and then operating the machine to move said cutter according to said program, whereby the final surface portion of such pattern is provided without repetitive cuts regardless of the amount of excess billet material.

Claim 5

The method of carving casting patterns as defined in claim 2, comprising the further steps of providing a machine with a second rotatable cutter having a cutting edge extending radially outward from its axis of rotation and following a conformation relative thereto which differs from such first cutter, and supplementing the carving program so provided for such first cutter with a program for such second cutter, under which it is directed immediately through any excess of billet remaining until its cutting edge reaches a final surface portion to be carved by said second cutter, and under which supplementary program said second cutter is then directed along such path that its cutting edge follows a portion of the final contour of the pattern to be carved by said second cutter, together with the step of operating the machine to direct said second cutter according to said supplementary program, whereby said second cutter carves final surface portions according to its conformation directly and without repetitive cuts.

Claim 6

As a new use for a tape-controlled milling machine, the method of carving a casting pattern as described in claim 2, which has, as part of its final contour, two surface portions joined by a radially curved internal fillet, comprising the steps defined in claim 2, in which the radius of the rotatable cutter so provided equals that of the fillet, and in which the carving program so provided directs the cutter edge along the final contour of the first of said two surface portions to a point at which the cutter axis coincides with the axis of said radially curved internal fillet, and there, directs the cutter edge, with an abrupt change of direction, to follow the contour of said second surface portion.

Claim 7

As a new use for a preprogrammed milling machine, the method of carving a casting pattern from a pattern material which is combustible under a charge of molten metal and whose density is less than 3 pounds per cubic foot, which pattern to be carved includes a surface portion depressed from other portions and extending transverse to the direction at which the axis of a rotatable cutter may conveniently be applied, comprising the steps of providing the machine with a rotatable cutter having a spindle axis of rotation, a cutting edge extending axially and spaced radially outward therefrom, and a tip-cutting edge portion extending transverse to its axis of rotation, and having the capacity to cut such material at more than five times the feasible depth of cut when machining steel, then chucking in the machine a billet of such combustible pattern material whose size exceeds that of the casting pattern to be carved therefrom, providing the machine with a carving program which provides such a linear feed rate and speed of cutter rotation as to achieve a rate of material removal at least 100 times as great as that for steel, and under which such cutter is plunged axially into the billet to such depth that its tip-cutting edge portion reaches the depth of final contour at which Such depressed surface portion is to be carved, and under which program the cutter is then directed through the billet along such path that its cutting edge follows at least part of the final contour of such transverse surface portion, and then operating the machine to move said cutter according to said program, whereby the tip cutting edge carves such final surface portion at its depth so depressed from such other pattern portions, while the tool portion thereabove removes the billet material thereabove.

Claim 8

As a new use for a preprogrammed milling machine, the method of carving a casting pattern from a pattern material which is combustible under a charge of molten metal and whose density is less than 3 pounds per cubic foot, which pattern to be carved includes a surface portion depressed from other portions and extending transverse to the direction at which the axis of a rotatable cutter may conveniently be applied, comprising the steps of providing the machine with a rotatable cutter having a spindle axis of rotation, a cutting edge extending axially and spaced radially outward therefrom, and a tip-cutting edge portion extending transverse to its axis of rotation, and having the capacity to cut such material at more than five times the feasible depth of cut when machining steel, then chucking in the machine a billet of such combustible pattern material whose size exceeds that of the casting pattern to be carved therefrom, providing the machine with a carving program which provides such a linear feed rate and speed of cutter rotation as to achieve a rate of material removal at least 100 times as great as that for steel, and under which such cutter is plunged axially into the billet to such depth that its tip-cutting edge portion reaches the depth of final contour at which Such depressed surface portion is to be carved, and under which program the cutter is then directed through the billet along such path that its cutting edge follows at least part of the final contour of such transverse surface portion, and then operating the machine to move said cutter according to said program, whereby the tip cutting edge carves such final surface portion at its depth so depressed from such other pattern portions, while the tool portion thereabove removes the billet material thereabove.