Patent GB-1231207-A (GB)
IPC: G05B19/408
Filed: 1967-10-21
Abstract: 1,231,207. Data conversion for machine-tool control. FERRANTI Ltd. 17 Jan., 1969 [21 Oct., 1967], No. 47983/67. Heading G4A. [Also in Division G3] Data conversion apparatus comprises input means for algebraically adding a signed input number to the contents of a write-in section 13A of a number store in dependence on the sign of the contents, then transferring the new contents to a read-out section 13B of the store and transferring the sign also, then as a further input number is added into the write-in section, reading out the number in the read-out section using a distributer 26 to produce a like number of output pulses spaced substantially uniformly over a time period defined by timing means, the output pulses being caused to represent the transferred sign, there being means to define an expanded time period equal to a predetermined number of the time periods above and throughout which alteration of the number being read-out is inhibited and an auxiliary distributer 102 reads out a number in an auxiliary store 14<SP>1</SP> as a like number of auxiliary output pulses spaced substantially uniformly over the expanded period and representing the sign of the number, the auxiliary and firstmentioned output pulses being algebraically added. A binary input number representing a velocity increment to be given in the X direction to the tool (or work-table) of a machine tool, is read at 12 from a tape 10 provided by a computer, and stored in a register 14<SP>1</SP>, then converted to a train of equal-valued pulses by ANDs G3/0 . . . G0/3 and OR 17, the ANDs being controlled by a binary counter distributer 102 driven by clock pulses B via AND 111. The data pulses are added to or subtracted from counter 13A according to the sign of the input number (applied from register 14<SP>1</SP> to gates 21, 22) and the sign of the present counter contents (applied from bi-stable 36 to switch 25). After the addition/subtraction (i.e. at the end of the current time period), the contents of 13A are gated to a register 13B via gates TG0-TG7. In the next time period, as a further velocity increment is applied to 13A, the number in 13B is converted to a train of equal valued pulses by ANDs G7/0 . . G/07 and OR 27, the ANDs being controlled by a binary counter distributer 26 driven by the clock pulses B. The data pulses are applied to a "forwards" or "backwards" line via OR 105 or 106 to control the machine tool (directly via a tape), according to the sign of the number in 13B, as indicated by a bi-stable 92 to which the sign was transferred from bistable 36 when the contents of 13A were gated to 13B. Thus each data pulse applied to a "forward" or "backward" line represents an increment of displacement. During the above operation, a decoder 101, on receiving a velocityincrement number from the tape, sets a bi-stable 114 which enables the above incrementing of the distributer 102. When this reaches its counting capacity, it resets bi-stable 114. When the computer sees a sequence of 16 intervals is required with zero (or essentially zero) velocityincrements, it applies a code to the tape 10 to indicate this and specify a corrective increment of displacement to be spread over the 16 periods. The code, read at 12, is decoded at 101 to energize a line SL and de-energize the normallyenergized SN. Bi-stable 114 is set as before, and the displacement-increment (binary) number is entered into register 14<SP>1</SP> to be passed as a train of equal-valued pulses by distributer 102 &c. to one of two gates 107, 108 according to the sign (as applied from register 14<SP>1</SP> to gates 21, 22), the output from 107 or 108 going to the "forward" or "backward" line via OR 105 or 106 respectively, being effectively added to the pulses from OR 27 (representing the contents of 13B). However, in this mode of operation, distributer 102 is incremented once, via AND 112, for every time period, rather than by every clock pulse B, and alteration of 13A is inhibited at gate 103. 256 clock pulses B occur per time period (this being the capacity of counter distributer 26). Each stage of each distributer 102, 26 controls the AND connected to the stage of complementary order of 14<SP>1</SP> or 13B. A clock pulse B<SP>1</SP> occurs shortly after each pulse B. The sign bi-stable 36 is loaded from register 14<SP>1</SP> whenever counter 13A holds zero. The tape is advanced every time period or every 16 time periods according to the mode of operation. Similar provisions may be made for Y movement, using the same tape 10 and distributer 102 if the 16-time-period mode of operation always occurs at the same time for both X and Y directions. The system is described as a modification of the Fig. 6 modification of Specification 1,139,253.