Template copying apparatus

Claim 2

In an apparatus for machining a workpiece by means of a tool under the control of a copy head sensing the form of a template, the apparatus comprising means for mounting the workpiece and the tool, means for producing relative machining movement between them in a controllably selected direction, means for mounting the template and the copy head and means for producing relative movement between the template and the copy head to correspond with the relative motion of the workpiece and the tool, the proviSion of: a follower mounted in the copy head to follow the form of the template; deviation demodulator means composed of a differentially wound inductive device to produce a continuously variable electrical signal output dependent upon deviation of the follower from a given relative datum position in the copy head; means to produce a series of reference electrical outputs of different values; means to compare the reference outputs with the variable signal output and to select the reference output corresponding to a particular signal output; control means to produce a predetermined movement of the copy head corresponding to the selected reference output; and means to furnish a stabilized DC voltage supply, said inductive device being formed by: a magnetic core movable by the follower; one winding connected to the stabilized DC voltage supply via a converter, and another, differentially wound, winding between the stabilized voltage supply and the comparison means.

Claim 3

In an apparatus for machining a workpiece by means of a tool under the control of a copy head sensing the form of a template, the apparatus comprising means for mounting the workpiece and the tool, means for producing relative machining movement between them in a controllably selected direction, means for mounting the template and the copy head and means for producing relative movement between the template and the copy head to correspond with the relative motion of the workpiece and the tool, the provision of: a follower mounted in the copy head to follow the form of the template; deviation demodulator means to produce a continuously variable electrical signal output dependent upon deviation of the follower from a given relative datum position in the copy head; means to produce a series of reference electrical outputs of different values; means to compare the reference outputs with the variable signal output and to select the reference output corresponding to a particular signal output, and control means to produce a predetermined movement of the copy head corresponding to the selected reference output, said comparison means comprising a plurality of comparator circuits each having two inputs formed by the electrical signal and a corresponding electrical reference, each comparator circuit being arranged to adopt one state or the other according to whether the electrical signal is greater or less respectively than the reference.

Claim 4

In an apparatus for machining a workpiece by means of a tool under the control of a copy head sensing the form of a template, the apparatus comprising means for mounting the workpiece and the tool, means for producing relative machining movement between them in a controllably selected direction, means for mounting the template and the copy head and means for producing relative movement between the template and the copy head to correspond with the relative motion of the workpiece and the tool, the provision of: a follower mounted in the copy head to follow the form of the template; deviation demodulator means to produce a continuously variable electrical signal output dependent upon deviation of the follower from a given relative datum position in the copy head; means to produce a series of reference electrical outputs of different values; means to compare the reference outputs with the variable signal output and to select the reference output corresponding to a particular signal output, and control means to produce a predetermined movement of the copy head corresponding to the selected reference output, said comparison means comprising a plurality of comparator circuits each having two inputs formed by the electrical signal and a corresponding electrical reference, each comparator circuit being arranged to adopt one state or the other according to whether the electrical signal is greater or less respectively than the reference.

Claim 5

An apparatus according to claim 2, wherein one of the comparator circuits is operative to switch an input of another of the comparator circuits from one electrical reference to another.

Claim 6

An apparatus according to claim 2, wherein the deviation demodulator means is adapted to produce the electrical signal in the form of a voltage which increases with increase in deviation; the electrical reference producing means is adapted to produce the electrical references in the form of reference voltages, and the comparison means is adapted to select the reference voltage immediately below the signal voltage.

Claim 7

An apparatus according to claim 4, wherein: the electrical reference producing means is adapted to produce six electrical reference voltages; the comparison means comprises four comparator circuits; a first one of the comparator circuits is connected to the second reference voltage in ascending order of magnitude; a second comparator circuit is connected selectively to the first or fourth reference voltage under the control of the first comparator circuit, according to whether the signal voltage is lower or higher respectively than the second reference voltage; the third comparator circuit is connected selectively to the third or sixth reference voltage under the control of the fourth comparator circuit, which is connected to the fifth reference voltage, according to whether the signal voltage is lower or higher respectively than the fifth reference voltage, and the four compaRator circuits controlling movement in a first direction, a perpendicular second direction, a third direction opposite to the first and a fourth direction opposite to the second, respectively.

Claim 8

Apparatus according to claim 4, wherein a zero adjustment means enables the making of contact between the follower and the template to coincide with the start of the growth of the signal voltage output from the deviation detector means.

Claim 9

Apparatus according to claim 6, provided with means to furnish a stabilized DC voltage supply, wherein the inductive device is formed by: a magnetic core movable by the follower; one winding connected to the stabilized DC voltage supply via a converter, and another, differentially wound, winding between the stabilized voltage supply and the comparison means, wherein the zero adjustment means comprises a micrometer element for adjusting core position in the differentially wound inductive device, and a potentiometer interposed between the stabilized voltage supply and the inductive device.

Claim 10

Apparatus according to claim 5, wherein an interlock is arranged to interrupt movement of the copy head when the deviation of the follower rises above a predetermined limit, the interlock being in the form of a fifth voltage comparator circuit connected to the variable signal voltage and to a seventh reference voltage, said fifth comparator circuit controlling a relay for interrupting copy head movement.

Claim 11

In an apparatus for machining a workpiece by means of a tool under the control of a copy head sensing the form of a template, the apparatus comprising means for mounting the workpiece and the tool, means for producing relative machining movement between them in a controllably selected direction, means for mounting the template and the copy head and means for producing relative movement between the template and the copy head to correspond with the relative motion of the workpiece and the tool, the provision of: a follower mounted in the copy head to follow the form of the template; deviation demodulator means to produce a continuously variable electrical signal output dependent upon deviation of the follower from a given relative datum position in the copy head; means to produce a series of reference electrical outputs of different values; means to compare the reference outputs with the variable signal output and to select the reference output corresponding to a particular signal output, control means to produce a predetermined movement of the copy head corresponding to the selected reference output, and means to adjust sensitivity to follower deviation, said sensitivity adjustment means being operative to adjust the value of a voltage divider producing the electrical references as voltages and comprising, in combination, a potentiometer for adjusting the voltage divider input voltage and an amplifier providing the variable electrical signal with only two fixed and manually selectable gains.

Claim 12

In an apparatus for machining a workpiece by means of a tool under the control of a copy head sensing the form of a template, the apparatus comprising means for mounting the workpiece and the tool, means for producing relative machining movement between them in a controllably selected direction, means for mounting the template and the copy head and means for producing relative movement between the template and the copy head to correspond with the relative motion of the workpiece and the tool, the provision of: a follower mounted in the copy head to follow the form of the template; deviation demodulator means to produce a continuously variable electrical signal output dependent upon deviation of the follower from a given relative datum position in the copy head; means to produce a series of reference electrical outputs of different values; means to compare the reference outputs with the variable signal output and to select the reference output corresponding to a particular signal output, control means to produce a predetermined movement of the copy head corresponding to the selected reference output, and means to adjust sensitivity to follower deviation, said sensitivity adjustment means being operative to adjust the value of a voltage divider producing the electrical references as voltages and comprising, in combination, a potentiometer for adjusting the voltage divider input voltage and an amplifier providing the variable electrical signal with only two fixed and manually selectable gains.