GB2045117A - Inserting components into printed-circuit boards - Google Patents

Abstract

Components, e.g. terminal pins, are inserted into a printed-circuit board under programmed control using a pin- insertion head which is charged with pins from a reciprocating shuttle. The insertion operation is executed after the board has been automatically positioned under the head by motors (20, 21) in accordance with the outputs from comparators (82, 83) that compare coordinates of actual board-position read out from strobed stores (84, 85) with demanded coordinates read out by a punched-tape reader (80). Each instruction on the tape includes a command for pin-insertion, or a 'jump' command by which response of the machine to the condition in which the difference between the actual and demanded coordinates is zero, is to proceed directly to execution of the next instruction so that the head is not then operated to insert a component. <IMAGE>

Description

SPECIFICATION Methods and machines for inserting components into printed-circuit boards This invention relates to methods and machines for inserting components into printed-circuit boards.

The invention is particularly, though not exclusively, concerned with methods and machines for inserting terminal pins into printed-circuit boards. With one common form of machine used for this purpose, pins are inserted in individual boards under operator control, the operator actuating the machine for insertion of each pin into the board. More particularly, the operator is required to position the board accurately beneath an insertion-head of the machine to locate the head where a pin is to be inserted, and then to actuate the machine to bring about the pin-insertion operation.

The requirementforthe operator to position the board accurately and to actuate the machine for insertion of each pin is wasteful of the operator's time and effort, and readily leads to errors. The operator's task is especialy tedious where a large number of pins are to be inserted in a large number of boards. Fully automatic machines that insert all the pins required for a board at the same time in one insertion operation are available, but they are expensive. More especially, fully automatic machines of this nature can be justified economically only if a very large continuous production run of identical printed-circuit boards is involved.There are many circumstances in which large and continuous production runs are not required and a fully automatic machine is not justified, and the present invention has for one of its objects improvement of methods and machine applicable in such circumstances.

According to one aspect of the present invention there is provided a method for inserting components into a printed-circuit board, wherein the board is moved automatically relative to a componentinsertion head to locate the head successively at different positions of the board in accordance with an ordered sequence of programmed instructions, each said instruction including coordinates of demanded board-position with respect to the head and an operation command, and wherein the method includes in respect of execution of each of at least some of said instructions of the sequence the steps of determining coordinates of the actual position of the board with respect to the head, comparing the coordinates of actual position and of demanded position with one another to determine the difference therebetween, moving the board to reduce the said difference towards zero, responding to the operation command when the said difference has been reduced to zero to operate said head to insert a component into the board, and responding to insertion of a component into the board to proceed to execution of the next instruction of the sequence.

According to another aspect of the present invention there is provided a machine for inserting components into a printed-circuit board, comprising a carrierforthe board, a component-insertion head, said carrier being movable relative to the head to locate the head successively at different positions of the board for insertion of individual ones of said components into the board at those positions, and automatic control means for moving the carrier means and operating the head in accordance with an ordered sequence of programmed instructions, each said instruction including coordinates of demanded board-position with respect to the head and an operation command which command, at least in some of the instructions of the sequence, is a component-insertion command, and wherein the control means comprises signal-supply means for supplying in respect of a selected one of the instructions signal representations of the coordinates of the demanded board-position and the operation command of that instruction, means for deriving signal representations of the coordinates of the actual position with respect to the head of the board as carried by the carrier means, means for comparing the signal representations of the coordinates of actual and demanded positions with one another to determine the difference therebetween, means for moving the carrier means to reduce the said difference towards zero, means for responding to signal representation of a component-insertion command to operate said head to insert a component into the board when the said difference has been reduced to zero, and means responsive to insertion of a component into the board to actuate said signal-supply means to select the next instruction of the sequence for execution.

Some instructions in the method and machine may include a jump operation-command by which operation of the head is omitted so that the response to the condition in which the difference between the actual and demanded positions has been reduced to zero, is in this case to proceed directly to execution of the next instruction. Use of such jump commands is advantageous in those circumstances where it is necessary to introduce detours into movement of the board with respect to the insertion head, between one position of insertion and the next.

The method and machine of the present invention may be readily applied to the insertion of terminal pins into printed-circuit boards.

A method and machine for inserting terminal pins into printed-circuit boards, in accordance with the present invention, will now be described, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a perspective view of part of a printed-circuit board during insertion of terminal pins therein; Figures 2 and 3 are respectively a front elevation and a plan of the pin-insertion machine; Figures 4 and 5 are side elevations of the pin-insertion machine illustrating successive stages of operation; Figure 6 is an enlarged sectional view of part of the pin-insertion machine, the section being taken on the line VI-VI of Figure 3; Figure 7 is an enlarged sectional view of a pin-insertion head and cooperating anvil of the pin-insertion machine; Figure 8 is an enlarged side view of part of the pin-feed system of the pin-insertion machine;; Figure 9 is a block schematic representation of the electrical control system of the pin-insertion machine; and Figure 10 illustrates the construction of a photoelectric reader of the pin-insertion machine.

The machine and method to be described are concerned with the insertion of terminal pins as illustrated in Figure 1, into printed-circuit boards.

Referring to Figure 1, each metal pin 1 is of square cross-section with flat longitudinal faces 2 and chamfered ends 3, and having an overall length and thickness of typically 16 mm and 1 mm respectively.

A multiplicity of pins 1 are inserted in each printedcircuit board 4 at spaced positions across its top surface 5 where connections for components and additional wiring are to be made to printed-circuit tracks 6 of the board 4. The board 4 has a hole 7 at one corner that together with a corresponding hole 7 at an adjacent corner (not shown), is used in the earlier stages of manufacture to establish a datum for the laying down of the tracks 6 on the board 4 and the piercing of the board 4 with circular holes 8 within the tracks 6 where the pins 1 are to be inserted; the holes 8 are plated-through after piercing so as to ensure electrical connection of the pins 1 with the tracks 6. The pins 1 are driven into the holes 8 by the machine so that each protrudes only slightly from the bottom surface 9 of the board 4.The fact that each pin 1 is of rectangular cross-section serves to enhance its retention within the board 4 and its electrical connection with the relevant track 6.

Referring more especially to Figures 2 and 3, the machine has a pin-insertion head 10 located vertically over an anvil 11 and operates automatically under control of a numerical-control unit 12 Figures 2 and 9). A carriage 13 for carrying the printed-circuit board 4 in the machine is mounted on mutually perpendicularslides 14 and 15to move in Xand Y coordinates respectively beneath the head 10, and is driven in these coordinates under program-control from the unit 12 to locate the holes 8 of the board 4 successively in register with the head 10 and anvil 11. When the carriage 13 is each time correctly positioned with one of the holes 8 in register with the head 1 O. force which holds the head 10 clear of the path of the carriage 13 as illustrated in Figures 2 and 4, is released.This allows the head 10 to fall under gravity onto the top surface 5 of the board 4, and the anvil 11 is at the same time driven upwardly to close upon the bottom surface 9; the resultant condition is as illustrated in Figure 5. A pin 1 supplied from a hopper 16 of the machine and already at this time loaded in the head 10, is then driven from the head 10 into the hole 8 against the anvil 11. The anvil 11 is the n retracted and the head 10 lifted and re-charged with another pin 1 while the carriage 13 is repositioned to bring the next hole 8 in register with the head 10.

Correct positioning of the carriage 13 and actuation of the machine to insert a terminal pin is achieved in accordance with punched tape 17 loaded into the unit 12. The tape 17 is programmed in accordance with the layout of the terminal pins required for the board and the optimum sequence of their insertion. The printed-circuit board 4 is loaded on the carriage 13 and clamped in place with its two datum-defining holes 7 engaged on pins 18 and 19 that are aligned with one another on the carriage 13 parallel to the X-coordinate slide 14. The tracks 6, and more particularly the holes 8 for receiving the pins 1, are thereby appropriately established in the X-Y coordinate system of the machine.Each carriage-positioning instruction is programmed in the form of the X and Y coordinates of the pin 18 required to position the relevant hole 8 in register with the head 10 for execution of the related pin-insertion instruction programmed on the tape 17.

The programmed control unit 12 supplies electrical pulses for controlling the X and Y displacements of the carriage 13, to electrical stepping motors 20 and 21. The motor 20 rotates a lead-screw 22 of the slide 14, whereas the motor 21 rotates a lead-screw 23 of the slide 15. The slide 15 (as illustrated, to enlarged scale, also in Figure 6) is carried by a saddle 24 which is mounted on the slide 14 by wheels 25 and which is coupled to a nut 26 Figure 2) on the lead-screw 22 so that the slide 15 is displaced in the X-coordinate direction in accordance with drive of the motor 20. The carriage 13 is similarly carried by a saddle 27 that is mounted by wheels 28 on the slide 15 and is coupled to a nut 29 (Figure 3) on the lead-screw 23, so that the carriage 13 is displaced in X- and Y-coordinates in accordance with the drives of the two motors 20 and 21 respectively.

The X and Y coordinates appropriate to the actual position of the carriage 13 are read out by photoelectric sensor units 30 and 31, the sensor unit 30 being carried by the saddle 24 to read out the X-coordinate from a code-plate 32 that extends lengthwise of the slide 14, and the unit 31 being carried by the saddle 27 to read out the Y-coordinate from a code-plate 33 that extends lengthwise of the slide 15. The signals read out are compared in the unit 12 with signal representations of the desired, programmed X and Y coordinates derived from the tape 17, and the motors 20 and 21 are both energized from the unit 12 in the appropriate senses to reduce any differences between the compared pairs of signals to zero.

When the comparison indicates that the correct, programmed positioning of the carriage 13 has been achieved, a command signal is issued by the unit 12 to a pneumatic control unit 34 of the machine, instructing insertion of a pin.

Pneumatic valves (indi#cated in broken outline only, in Figure 3) within the control unit 34 regulate application of air pressure to pneumatic actuators 35 and 36 coupled to the head 10 and anvil 11 respectively, in a sequence appropriate to achieve closing of the head 10 and anvil 11 onto the board 4, insertion of the relevant pin 1, and then withdrawal of the head 10 and anvil 11 ready for re-positioning of the board 4. The actuator 36 is double-acting, being powered to close the anvil 11 onto the bottom surface 9 of the board 4 and hold it there, in response to the pin-insertion command signal and until the pin has been inserted. The actuator 35 is also double-acting and is normally powered in its reverse sense to hold the head 10 lifted up out of the path of the carriage 13.Pneumatic power to the actuator 35 is released in response to the pin-insertion command signal from the unit 12, this allowing the head 10 to fall freely onto the top surface 5 of the board 4.

The pin-insertion head 10 is part of an assembly (best seen in Figure 4) that is coupled to the piston-rod 37 of the actuator 35, and projects downwardly from a shuttle mechanism 38 carried at the lower end of a vertically-mounted hollow shaft 39. The rod 37 extends freely through a plate 40 secured to the upper end of the shaft 39, into a bore 41 of the shaft 39 that terminates at the upper end in an annular shoulder 42. Within the bore 41 the rod 37 is coupled to the cylindrical head 43 of a downwardly-extending pin-driving rod 44. The head 43 is a sliding fit within the bore 41 and aligns the rod 44 appropriately with a guide 45 at the lower end ready for passage through the shuttle mechanism 38 into the head 10 when insertion of a terminal pin is to be effected.However while the actuator 35 is powered in its reverse sense to hold the head 10 clear of the board 4 as illustrated in Figure 4, the rod 37 is urged upwardly to hold the pin-driving rod 44 withdrawn from the shuttle mechanism 38 and with its cylindrical head 43 abutting hard upon the should 42 of the shaft 39. The shaft 39 is slidable vertically within its mounting 46 on the machine frame 47, and is drawn upwardly with the rod 37 by the abutment of the upwardly-drawn head 43 upon the shoulder 42. The extent of upward movement of the shaft 39, and accordingly of the whole pin-insertion assembly including the head 10, is limited by abutment of a stop 48 carried by the plate 40, with a bracket 49 of the frame 47.

When the pin-insertion command signal is receivedfrom the unit 12 and pneumatic powertothe actuator 35 is in consequence released, the weight of the pin-insertion assembly draws the rod 37 downwardly. More particularly, the shaft 39 carrying the shuttle mechanism 38 and head 10, slides downwardly drawing the rods 37 and 44 with it under the abutment of the shoulder 42 with the head 43. The downward movement is arrested with the head 10 in contact with the upper surface 5 of the board 4, by abutment of the plate 40 with the mounting 46. An electrical micro-switch 50 mounted on the frame 47 is actuated from the plate 40 during the final part of closing of the head 10 onto the surface 5, and this triqgers the control unit 34 to power the actuator 35 in its forward sense for pin insertion.

'towering of the actuator 35 in the forward sense drives the rod 37 downwardly to break abutment between the head 43 and the shoulder 42, and to push the rod 44 down through the shuttle mechanism 38 onto the pin 1 already loaded as illustrated in Figure 7, in the head 10. As shown in Figure 7, the pin 1 is retained in the head 10 against a small steel ball 51 that is held captive by a rubber sleeve 52 encircling the head 10. Downward drive of the rod 44 onto the pin 1 forces the pin past the resilientlyloaded ball 51 and into the aligned hole 8 of the board 4.The extent to which the ball 51 can be deflected against the elastic restraint of the sleeve 52 is clnly sufficient to allow passage of the pin if it is ori anted squarely to the ball, that is to say such that one or other of its four longitudinal flat faces 2 runs against the ball 51; the drive applied by the rod 44 ensures that any necessary reorientation of the pin 1 to achieve this 'squareness' takes place through the initial impact of the lowermost chamfered-end 3 of the pin 1 on the ball 51 itself. Thus the pin 1 is inserted in the board 4 with an orientation, determined by the orientation of the ball 51 in the machine, that is uniform from one pin to the next inserted in the board 4 from the head 10.

The depth of insertion of the pin 1 in the board 4 is determined by the stroke of the rod 37, the lowermost end of the pin 1 projecting from the bottom surface 9 of the board 4 and depressing a plunger 53 (Figure 7) within the anvil 11. The anvil 11 is at this time held closed upon the surface 9 by the actuator 36, and depression of the plunger 53 operates an electrical microswitch 54 (Figures 4 and 5) to signal to the unit 12 that a pin has been inserted. An electrical microswitch 55 on the mounting 46 is also operated by an arm 56 carried with the rod 37 when the rod 37 reaches the end of its pin-insertion stroke.

Operation of the microswitch 55 is signalled to the pneumatic control unit 34 to power the actuator 36 for withdrawal of the anvil 11, and also to power the actuator 35 in its reverse sense. Powering of the actuator 35 in its reverse sense withdraws the rod 44 from the head 10 and shuttle mechanism 38, lifting the head 43 into abutment again with the shoulder 42 so that the shaft 39 is drawn upwardly and lifts the shuttle mechanism 38 and the head 10 until arrested by abutment once again of the stop 48 with the bracket 49. The shuttle mechanism 38 is actuated during the upward movement of the assembly to recharge the head 10 with a pin 1 ready for the next pin-insertion operation.

Referring especially to Figure 4, the shuttle mechanism 38 includes a slide 57 that is driven transversely of the shaft 39 between forward (as illustrated in Figure 4) and backward positions by a double-acting pneumatic actuator 58. The slide 57 has a bore 59 that aligns with the rod 44 and the head 10 when the slide 57 is in its forward position and a bore 60 that is correspondingly aligned with them when the slide 57 is in its backward position.

While the bore 59 is aligned with the rod 44 and head 10 (as illustrated in Figure 4), the bore 60 is on the other hand aligned with an inlet passage 61 and receives from this a pin 1 supplied via a tube 62.

Thus during the next, backward stroke of the slide 57 the pin loaded in the bore 60 is translated sideways to be brought at the end of the stroke into alignment with the head 10 so that it falls out of the bore 60 clear of the slide 57, onto the ball 51 to recharge the head 10 once again. This backward stroke brings the bore 59 into alignment with an inlet passage 63 to receive a further pin 1 supplied via a tube 64, ready for the next, forward stroke of the slide 57 following insertion of the pin last loaded into the head 10 from the bore 60. This forward stroke will recharge the head 10 with the pin from the bore 59 and again re-load the bore 60 from the passage 61.

Pins 1 are supplied one by one into the passages 61 and 63 down the tubes 62 and 64 respectively, from an upper shuttle mechanism 65. The mechan ism 65 includes a slide 66 that is driven backwards (as illustrated in Figure 8) and forwards in synchron ism with the forward and backward strokes respec tively of the slide 57, by a double-acting pneumatic actuator 67 (Figure 3). As illustrated in Figure 8, the slide 66 has a bore 68 that is #aligned with a pin-supply passage 69 when the slide 66 is in its backward position, and a bore 70 that is correspond ingly aligned with the passage 65 when the slide 66 is in its forward position. When the bore 68 is aligned with the passage 69, the bore 70 is aligned with a passage 71 leading into the tube 64, whereas the bore 68 is aligned with a passage 72 leading into the tube 62 when the bore 70 is aligned with the passage 69.Thus pins 1 received in turn in the bores 68 and 70 from the passage 69 are distributed to the tubes 62 and 64 respectively, upon the successive forward and backward strokes of the slide 66.

The pin-supply passage 69 is maintained full of pins 1 ready to enter the bores 68 and 70 in turn, from the hopper 16. The hopper 16 has an internal helical shoulder 72 (see especially Figure 3) that rises from within the hopper 16 with progressively increasing radius to align at the top with a passage 73 that is coupled via a chamber 74 to the passage 69. An electrically-powered vibrator 75 (Figure 2) vibrates the hopper 16 causing pins 1 loaded into the hopper 16 to align themselves on the shoulder 72 and to rise progressively "nose to tail" up the shoulder 72 and enter the substantially horizontal passage 73. Turning of the pins 1 through a right angle to pass from the passage 73 into the vertical supply-passage 69 is achieved in the chamber 74.

The chamber 74, which has the shape of a quadrant of radius substantially equal to the pin length and centred on the conjunction of the pas sages 69 and 73, has a horizontal 'radius' wall 77 aligned with the passage 73. Air is supplied under pressure via a pipe 76 to enter the chamber 74 as an upward jet through a vent 78 in the wall 77. The vent 78 is located substantially at the radial extremity of the wall 77 so that each pin 1, urged progressively along the passage 73 by the following pins on the shoulder 72 ofthevibrating hopper 16, is pushed wholly into the chamber 74 along the wall 77, before its leading end 3 reaches the vent 78. When the leading end 3 reaches the vent 78 it is lifted upwardly from the wall 77 by the jet of air issuing through the vent 78, tipping the pin 1 so that its trailing end 3 enters the vertical passage 69.The junction of the wall 77 with the passage 69 is machined to provide a rounded shoulder 79 that assists to tip the pin nearly into the vertical, and eases entry of the trailing end 3 into the passage 69. The pin 1 is accordingly free to fall easily into the vertical passage 69 from the chamber 74 so as to be ready for distribution in its turn from the upper shuttle mechanism 65 via either We e tube 62 or 64 to the lower shuttle mechanism 38 and thence to the head 10 for insertion into the board 4 4according to the pin-insertion program.

The overall rate of pin-insertion programmed is less than the rate of pin feed urged from the vibrating hopper 16. Accordingly there soon becom es an end-to-end build-up of pins 1 in the passages 73 and 69 after commencement of machine operation. This build-up is relieved transitorily only upon each stroke of the shuttle mechanism 65 allowing the lowermost pin in the passage 69 to fall into the bore 68 or 70 as the case may be. Congestion in the chamber 74 is however precluded by the uppermost pin in the passage 69. In this respect the length of the passage 69 is chosen so that a portion (about one-half) of the uppermost pin in the passage 69 remains projecting upwardly into the chamber 74 (as illustrated in Figure 8). This blocks advance of the next following pin 1 from the passage 73 into the chamber 74.It is only when the next stroke of the shuttle mechanism 65 takes place to admit the lowermost pin 1 in the passage 69 to one or the other of the bores 68 and 70, that the blockage is cleared by fall of the uppermost pin wholly into the passage 69 when the other pins in passage 69 descend. The nextfollowing pin 1 is then advanced into the chamber 74 to be tipped up by the air jet from the vent 78 and enter the passage 69 to stand upon its preceding pin, and thereby itself now block pin-entry into the chamber 74 from the passage 73, until the next stroke of the shuttle mechanism 65. The next stroke of the shuttle mechanism 65 takes place in synchronism with that of the shuttle mechanism 38, following insertion of a pin and during re-positioning of the carriage 13 ready for insertion of the next pin from the head 10.

Overall control of the machine in positioning the carriage 13 and inserting pins 1 into the board 4 is effected by the unit 12 in accordance with the programmed instructions of the tape 17. The construction of the unit 12, together with its interconnection with other components of the machine, is illustrated schematically in Figure 9; the unit 12 and its operation will now be described with reference to that figure.

Referring to Figure 9, instructions on the tape 17 are read in turn within the unit 12 by a tape-read unit 80 and are signalled electrically to a decode-andstore unit 81. Each instruction includes identification of the X- and Y-coordinate values Xd, and Yd, of a demanded position of the head 10, together with an operation command appropriate to that demanded position. Electric signals in accordance with the values Xd and Yd are supplied respectively to an X-comparator unit 82 and a Y-comparator unit 83 for comparison with the actual X and Y coordinate values, Xa and Ya, that relate the position of the carriage 13 to the head 10. These values Xa and Ya are signalled to the units 82 and 83 respectively from buffer stores 84 and 85 that receive the outputs of the photoelectric readers 30 and 31.

The photoelectric reader 30, as illustrated in Figure 10 (and similarly the photoelectric reader 31), includes a column of ten light-emitting diodes 86 located on one side of the code-plate 32 and a parallel column of ten photo-responsive diodes 87 located on the other side. The diodes 86 emit infra-red light towards the code-plate 32, and each diode 87 provides an output signal in dependence upon whether light is received through the codeplate 32 from a respective one of the diodes 86. Each diode 87 accordingly provides an output in dependence upon whether it is in register with a hole in the code-plate 32 (or code-plate 33). The code-plate 32 (and similarly the code-plate 33) has a regular series of small holes 88 running throughout its coded length so as to define a multiplicity of discrete code positions separated from one another by increments of 0.1 inch (2.5 mm).Up to nine larger-diameter holes 89 are distributed across the width of the plate at each code position to provide a combination of holes characteristic by their number and distribution of that position. Accordingly the diodes 87 of the reader 30, acting in conjunction with the code-plate 32, provide a combination of outputs to the buffer store 84 characteristic of the value of Xa. The ten photo-responsive diodes of the reader 31 acting in conjunction with the code-plate 33, correspondingly provide a combination of outputs to the buffer store 85 characteristic of the value Ya.

The values of Xa and Ya signalled to the buffer stores 84 and 85 are entered into those stores under control of pulses supplied by strobe units 90 and 91 driven from the motors 20 and 21. Each unit 90 and 91 includes a diode 92 associated with a slotted disc 93 that is rotated by the relevant motor 20 or 21 to bring one or the other of two diametrically-opposed narrow slots 94 of the disc 93 into alignment with the diode 92 for each code-position increment in the respective X- and Y-coordinate. Light from a source 95 on the opposite side of the disc 93 passes to the diode 92 whenever one of the slots 94 comes into alignment with the diode 92, so that a succession of pulses related accurately to the achievement of successive increments of movement, are derived.

The pulses supplied fromthe diode 92 of the unit 90 serve to effect change in the indication of the value Xa stored and signalled by the buffer store 84, whereas the pulses supplied from the diode 92 of the unit 91 serve to effect change in the value of Ya stored and signalled by the buffer store 85.

The values of Xa and Ya signalled from the buffer stores 84 and 85 are compared with the values Xd and Yd respectively, in the units 82 and 83, to determine the magnitude and sense of the corrections in the values Xa and Ya required to bring the carriage 13 to the demanded position. The correction in the value of Xa is signalled from the unit 82 to a unit 96 that controls energization of the motor 20 to drive the lead-screw 22 of the X-slide 14 via a gearbox 97. The correction in the value Ya is on the other hand signalled from the unit 83 to a unit 98 that controls energization of the motor 21 to drive the lead-screw 23 of the Y-slide 15 via a gearbox 99.The motor-control units 95 and 97 energize the respective motors 20 and 21 with pulses, such pulses being supplied at a frequency and in a sense dependent up )n the magnitude and sense of the relevant correction required.

The motors 20 and 21 continue to be energized from the units 96 and 98 until the values of Xa and Ya have been brought to equality with the demanded values Xd and Yd, that is to say, until the carriage 13 is located beneath the head 10 in accordance with the relevant instruction read from the tape 17. The condition in which there is equality between the values of Xa and Xd is detected by the comparator unit 82 and is signalled thereby to a function-control unit 100, whereas the condition in which there is equality between Ya and Yd is detected and signalled to the unit 100 by the comparator unit 83. The unit 100 receives from the decode-and-store unit 81 a signal in accordance with the operation command of the instruction read from the tape 17, and responds to receipt of both equality-indicating signals from the units 82 and 83, to act on the relevant command.The command will in general instruct insertion of a pin, and in this event the unit 100 issues the appropriate command signal to the pneumatic control unit 34 required to initiate the pin-insertion sequence. Insertion of the pin in accordance with the command is signalled back to the unit 100 from the microswitch 54, and the unit 100 in response to this signals the tape-read unit 80 to advance the tape 17 to read out the next programmed instruction.

The instructions read from the tape 17 may include so-called 'jump' operation-commands, such commands being utilized where it is necessary for movement of the carriage 13 from one position of pin insertion to the next to be other than along a direct path. For example, where certain components or other items are already mounted on the board before pin insertion, it may be necessary to ensure that such items are not moved beneath or too close to the head 10; the programming of carriagemovement for this can be achieved by using a series of step-movements in different directions. The stepmovements are programmed on the tape 17 in terms of the X- and Y-coordinates of the way-points at which direction change is required, but in this case the operation command included in each instruction is a 'jump' command distinct from the pin-insertion command.When a signal in accordance with a 'jump' command is supplied from the unit 81 to the unit 100 in respect of an instruction from the tape 17, the unit 100 responds to the two equality-signals supplied from the comparator units 82 and 83 to signal the tape-read unit 80 to advance the tape 17 to the next instruction, without issuing a command signal to the pneumatic control unit 34.

To the extent that control of the machine has so far been described it is effective to move the carriage 13 and accurately locate it with respect to the head 10 in code-defined positions spaced from one another by increments of 0.1 inch (2.5 mm). Where intermediate locations are required these are achieved to an accuracy of 0.001 inch (0.025 mm) by including additional digits of lesser or 'fine' significance in the values of Xd and Yd programmed on the tape 17.

Positioning of the carriage 13 to the nearest X and Y code positions is carried out as described above, in accordance with the most-significant digits of the values of Xd and Yd, to obtain coarse positioning.

Once this has been achieved the units 82 and 83 then act to supply individual pulses to the motors 20 and 21 respectively, via the motor control units 96 and 98, in accordance with the 'fine' digits of Xd and Yd.

These pulses serve to step the motors 20 and 21 on the appropriate number of steps to achieve the required intermediate positioning.

Claims (10)

1. A method for inserting components into a printed-circuit board, wherein the board is moved automatically relative to a component-insertion head to locate the head successively at different positions of the board in accordance with an ordered sequence of programmed instructions, each said instruction including coordinates of demanded board-position with respect to the head and an operation command, and wherein the method includes in respect of execution of each of at least some of said instructions of the sequence the steps of determining coordinates of the actual position of the board with respect to the head, comparing the coordinates of actual position and of demanded position with one another to determine the difference therebetween, moving the board to reduce the said difference towards zero, responding to the operation command when the said difference has been reduced to zero to operate said head to insert a component into the board. and responding to insertion of a component into the board to proceed to execution of the next instruction of the sequence.

2. A method according to Claim 1 wherein one or more of the instructions include a jump operationcommand, the method including in respect of each such one or more instructions the steps of determining coordinates of the actual position of the board with respect to the head, comparing the coordinates of actual position and of demanded position with one another to determine the difference therebetween, moving the board to reduce the said difference to zero, and responding to the jump operationcommand when the said difference has been reduced to zero to proceed to execution of the next instruction of the sequence without operation of said head.

3. A method according to Claim 1 or Claim 2 for inserting terminal pins into the board.

4. A machine for inserting components into a printed-circuit board, comprising a carrierforthe board, a component-insertion head, said carrier being movable relative to the head to locate the head successively at different positions of the board for insertion of individual ones of said components into the board at these positions, and automatic control means for moving the carrier means and operating the head in accordance with an ordered sequence of programmed instructions, each said instruction including coordinates of demanded board-position with respect to the head and an operation command which command, at least in some of the instructions of the sequence, is a component-insertion command, and wherein the control means comprises signal-supply means for supplying in respect of a selected one of the instructions signal representations of the coordinates of the demanded boardposition and the operation command of that instruction, means for deriving signal representations of the coordinates of the actual position with respect to the head of the board as carried by the carrier means, means for comparing the signal representations of the coordinates of actual and demanded positions with one another to determine the difference therebetween, means for moving the carrier means to reduce the said difference towards zero, means for responding to signal representation of a component-insertion command to operate said head to insert a component into the board when the said difference has been reduced to zero, and means responsive to insertion of a component into the board to actuate said signal-supply means to select the next instruction of the sequence for execution.

5. A machine according to Claim 4wherein said carrier means is mounted for movement in each of two mutually-perpendicular coordinate directions, and said means for deriving signal representations of the coordinates of the actual position of the board comprises in respect of each coordinate direction, coding means for providing digital representation of the displacement of the carrier means in that coordinate direction, means to generate a strobe signal in response to successive unit-distance increments of movement of the carrier means in said coordinate direction, and store means responsive to the strobe signal to enter into the store means the digital representation then being generated by said code means.

6. A machine according to Claim 4 or Claim 5 including a reciprocating shuttle that is arranged to translate the components to re-charge the head with one component at a time, in response to each insertion operation.

7. A machine according to any one of Claims 4 to 6 wherein the head is arranged to be raised and lowered with respect to the carrier means, the head being lowered to make contact with the board in response to a said component-insertion command when the said difference has been reduced to zero, and then raised in response to insertion of a component from the head into the board.

8. A machine according to any one of Claims 4 to 7 for inserting terminal pins into the printed-circuit board, including an anvil for contacting the board beneath the said head, and means for generating a signal to indicate insertion of a pin into the board in response to penetration of the board onto the anvil of a pin inserted from the head.

9. A method for inserting terminal pins into a printed-circuit board, substantially as hereinbefore described with reference to the accompanying drawings.

10. A machine for inserting terminal pins into a printed-circuit board, substantially as hereinbefore described with reference to the accompanying drawings.