GB2158238A

GB2158238A - Component insertion machine

Info

Publication number: GB2158238A
Application number: GB08411271A
Authority: GB
Inventors: Fred Richard Vaughan
Original assignee: Standard Telephone and Cables PLC
Current assignee: STC PLC
Priority date: 1984-05-02
Filing date: 1984-05-02
Publication date: 1985-11-06
Also published as: GB8411271D0; GB2158238B

Abstract

In a computer-controlled automatic component insertion machine for producing printed circuit boards, guide pins move into holes in the board from under the board and component leads on insertion engage the pins and enter the holes as the pins retract. If positioning is inaccurate, the leads and/or the pins hit the board and may be damaged. To check accuracy of positioning, a setting plate is made with an accurately located pattern of holes, and the machine is controlled by a programme appropriate to that pattern. When the board is positioned, as if for an insertion, the guide pins are offered up to the board, and any inaccuracy noted from the relative positions of pins and holes. Such errors are noted and used to correct the machine's positioning system.

Description

SPECIFICATION Component insertion machine This invention relates to automatic component insertion machines, and to arrangements for testing such machines.

The arrangement to be described is intended for use with a fully automatic computer-controlled component insertion machine, used for inserting so-called 'radial-leaded' electronic components into printed circuit boards. Such components are usually round (or possibly oval) in cross-section, with leads extending radially outwards. To insert these leads, into holes in a board they are bent until they are substantially parallel to each other. In the particular machine the control is by a microcomputer working in a semi-closed loop system with DC servomotors. The programme input is by paper tape via a "Teletype" terminal. Component input is via a multi-station magazine at the rear of the machine, and components are supplied in sprocket tape.

Under programme control the components are selected, one at a time, from the input magazine, cut from the tape which carries them, and fed to the insertion head for insertion into a printed circuit board. The board to be fitted with components, which has previously been loaded to a board holder which is part of the machine is then positioned by X and Y axis movement into a position with respect to the head which is appropriate to the component to be inserted. This positioning is by X and Y axis DC servomotors and leadscrews, under programme control.

When the board has been positioned, two pins, which in one machine are 0.95 mm diameter, are passed through the component holes in the board. This indicates to the control system that the board and the head are in the correct relevant positions. The component in the insertion head is then transferred mechanically via an insertion head pusher into the component location holes in the board. The leads of the component, during this stage, enter the holes from the upper surface, whereas the pins entered it from the under surface. During this stage, the pins are fully retracted as the component leads move towards and into the holes, and a cut and clinch unit on the underside of the board cuts the component leads to length and "clinches'' the component leads to secure the component to the board.

The above cycle is then repeated until all the components for the board under the head have been inserted. The board is then removed from the machine's board holder, and the complete cycle is repeated for subsequent printed circuit boards.

It will be seen that machine positioning accuracy in the X and Y axis is extremely critical for component insertion reliability; and mis-positioning in either axes causes component mis-insertion and may also cause bending or breaking of the guide pins, which as indicated above are thin.

An object of the invention is to make it possible to check the accuracy of the machine's positioning arrangements prior to using it in production.

According to the present invention, there is provided a method of testing an automatic component insertion machine of the type which inserts the component's leads into holes in å circuit board under computer control, in which a setting plate with a pattern of holes which simulates the pattern of holes on a circuit board to be fitted with components is placed on the machine in the position used for such a circuit board, in which the insertion machine is then so controlled as to set it to the positions to be used to insert components into a said circuit board, in which guide pins used to assist component lead insertion into the holes are offered up to the board and the relation between each such offering up and the holes is checked, and in which the results of said checking are usable to correct the machine's control arrangements.

The method to be described uses a setting plate which in effect simulates a circuit board to be worked on, and which has a pattern of holes which is appropriate to such a board.

These reference holes were, in one specific example, jig-board accurately into known coordinate positions, and a programme was written to drive the machine to those positions.

This machine positioning is controlled in absolute X and Y co-ordinates from a known machine datum point.

After each positioning of the machine the accuracy is checked by in effect noting whether the pins move into the holes. If they do so without fouling the plate then it is assumed that the positioning is correct. After a complete run has been done in this manner, the inaccuracies (if any) of the positioning arrangements are noted, and suitable adjustments can then be made.

An optical correction arrangement is available with some machines; this has a light source below the board (or setting plate) with a TV camera above the board (or setting plate). Hence the picture as seen by the TV camera during the positioning sequence indicates the degree of error if any.

It will be understood that the method described above is usable with a variety of different component insertion machines.

Claims

1. A method of testing an automatic component insertion machine of the type which inserts the component's leads into holes in a circuit board under computer control, in which a setting plate with a pattern of holes which simulates the pattern of holes on a circuit board to be fitted with components is placed on the machine in the position used for such a circuit board, in which the insertion machine is then so controlled as to set it to the positions to be used to insert components into a said circuit board, in which guide pins used to assist component lead insertion into the holes are offered up to the board and the relation between each such offering up and the holes is checked, and in which the results of said checking are usable to correct the machine's control arrangements.

2. A method of testing a component insertion machine, substantially as herein described.

CLAIMS New or amended claims:

3. A method of testing the accuracy of the positioning system of an automatic compnent insertion system of the type which inserts the leads of the components into holes in a circuit board under processor control, in which a setting plate with an accurately located pattern of holes which corresponds to the pattern of holes on a circuit board to be fitted with components is fitted to the insertion table of the component insertion machine, in which the machine is then controlled by a processor programme appropriate to the hole pattern of the setting plate so as to successively set to a number of positions each of which is appropriate to the insertion of a component, in which in each said position guide pins of the machine used to assist component lead insertion into the holes are offered up to the setting plate and the relation between each such offering up and the holes in the setting plate is checked, and in which if the results of said checking indicate any error in the positioning of the machine such results are used to correct the positioning system of the machine's table