WO1992010922A1

WO1992010922A1 - Machines for automatic removal of protective film from boards for making printed circuits

Info

Publication number: WO1992010922A1
Application number: PCT/IT1991/000010
Authority: WO
Inventors: Bruno Ceraso
Original assignee: Cedal S.R.L.
Priority date: 1990-12-04
Filing date: 1991-02-18
Publication date: 1992-06-25
Also published as: IT9022276A0; AU7306491A; IT9022276A1; IT1246493B

Abstract

Machine (10) for removal of protective films (81, 82) from boards (80) for making printed circuits, comprising devices (20-22, 30-32, 43, 45) for correctly and automatically placing each board (80), by means of a slide (30) on a plane of motor-driven rollers (12) and for discharging said board at the end of the operation, devices (50, 54) for detaching, by means of a pair of contraposed knurled wheels, an edge of the protective film (81, 82) and for raising said edge by use of a jet of compressed air, devices (18, 19, 40, 41, 90) for gradual removal of the films (81, 82) acting on the raised edge by pincers (90) provided with suction nozzles, and devices for discharging the removed films (81, 82) into containers placed to receive them.

Description

MACHINES FOR AUTOMATIC REMOVAL OF PROTECTIVE FILM FROM BOARDS FOR MAKING PRINTED CIRCUITS

The invention concerns a machine for servicing boards for printed circuits. Systems and procedures for preparing and processing boards for printed circuits are well known.

These boards are covered with a protective film on both sides applied so as to ensure perfect adherence and sta¬ bility. Such close adherence obviously creates problems when workers have to spend time taking the film off boards and this is so partly because it is difficult to start lifting the film and partly because of the risk of damaging the highly delicate surfaces of the board while doing it. The above machine solves these problems thereby considera¬ bly reducing working times and costs.

Subject of the invention is a machine for removal of pro¬ tective films from boards to make printed circuits. Said machine comprises devices for automatically placing each sheet in position on a surface of motor-driven rol¬ lers and for discharging it when the film is' off, devices for raising and detaching an edge of the protective film, devices for gradually lifting off the film acting on the raised edge, and devices for discharging the detached film into a special container.

The devices for detaching and lifting up an edge of the protective film comprise a means for neutralizing the ad¬ herence between the board and the edge of the film by crea¬ ting spaces and discontinuous points between said board and said edge, and comprise a means for raising said edge so that a pincer and the like can take hold of .it. The means for neutralizing adherence between the board and the edge of film, creating discontinuity and spaces between said board and said edge, is a U-shaped siide, ransla ing parallel to the plane on which the board moves, fitted with a pair of knurled contraposed small wheels, the one kept pressing against the other by a spring, said wheels freely rotating round axes transversal to the movement of the slide and supported respectively by the one and the other of the parallel plates forming the U. The trajectory of the U-shaped slide is such that the board moves into it little by little and, simultaneousl ,the knurled wheels act on the edges of the film to be removed, film that is applied on both faces of the board, in such a way that said edges are detached at the same time. The means for lifting up the edge of the film is preferably a jet of compressed air directed against points of discon¬ tinuity and spaces between the edges of film and the board. The devices for gradual removal of the film, acting on the raised edges, comprise a pincer composed of a jaw and a head that, when the "cycle for removing the film starts,move close in to the raised edge in a position substantially orthogonal to the board.

A nozzle connected to a circuit sucking in air opens onto said jaw. The effect of the suction is to cause the raised edge to adhere to the plane of the jaw and then to the mouth of the nozzle.

Consequently, due to increased depression in the suction circuit, a pneumatic cylinder, connected to said suction circuit, comes into action causing the pincer to close and the edge of film to he held between the two jaws. Said pincer is supported by an arm mounted perpendicu¬ larly to the shaft of an electric motor which, once the pincer is closed, begins rotating thus pulling on the film and gradually detaching it from the board, thence to a container for detached film.

On reaching said container the pincer opens allowing the film to fall down into it.

Preferably the pincer is placed symmetrically in relation to another similar one. The two pincers act as a pair respectively on one film and on the other applied to the two faces of the board. In this way both films, one on the upper face and one on the lower face of the board ,are detached simultaneously and gradually . Movement of one pincer, directed upward, is made from a position close to the board until the upper face's film is fully removed.

Movement of the second pincer, directed downward, is^' made from a position close to the board until the lower face's film is fully removed.

Pincer movements are completed on reaching a container for collecting removed film.

The film is gradually detached by the pincer pulling the raised edge and rolling the film round a parallel rod above the board, in a direction perpendicular to the board's plane of movement, or else towards the side of the board opposite to the raised edge.

The effect of this pulling movement on the board is to make it advance orthogonally or opposite to said direction of pull while the film is becoming slowly detached until it has entirely left the surface of the board. Preferably the pincer is placed symmetrically to another one similar to it, symmetrically in relation to the board's •plane of movement.

Therefore, due to a simultaneous pull on the upper and low¬ er films applied to the board, said board advances in an orthogonal direction or opposite to said pulling force while, the two films - the first passing round a rod above and pa¬ rallel to the board and the second film passing round another rod parallel to and below the same board - are simultaneously detached from the board to which they were applied. The devices for automatically positioning the boards for printed circuits on the plane of motor-driven rollers com¬ prise a transversal shoulder fixed on one side of said plane, a mobile shoulder placed on the other side of said plane trans¬ latable on bars,put there for the purpose, in a direction parallel to the motor-driven rollers and controlled by a pneu¬ matic cylinder, a rectangular cross piece parallel to said rollers, moving on a terminal pin and controlled by a pneu¬ matic cylinder that allows it two end-stroke positions - an upper one that interferes with the movement of the board and a lower one below the board's trajectory -,a pressure head for holding the board in position on the roller plane, con¬ trolled by a pneumatic cylinder, a sensor placed by the fixed shoulder on the same level as that of the board, another sen¬ sor placed immediately below the plane over which the board moves at the end of the position it assumes in the zone of contact with the above mentioned cross piece. When given the order to start up, the motor-driven rollers transfer the board until its front end comes up against the oscillating cross, piece. The sensor below the board's plane of movement, as soon as it has sensed the board, controls movement of the mobile shoul¬ der which pushes the board till it touches the fixed shoulder. The sensor placed on the fixed shoulder stops movement of the mobile shoulder and operates the pressure head which holds the board in the position it has reached, lowers the oscillating cross-piece to its lower end-stop and starts the cycle to remove the film from the board. The advantages of the invention are clear.

Once the board for making printed circuits is laid in po¬ sition on the machine's plane of rollers and once said ma¬ chine has been started up, the films applied to both surfaces of the board are automatically and simultaneously detached, the removed films are discharged into a container for the purpose and the clean board is ready for use without having been touched by the operator.

All this is done speedily, simply and safely avoiding any damage to the board.

Characteristics and purposes of the invention will be made still clearer by the following example of its execution il¬ lustrated by diagrammatic figures.

Fig.1 The machine subject of the invention seen in perspec- tive at the start of its cycle with a board for printe circuits lying on the plane of rollers. Fig.2 Perspective view of the machine with the board placed longitudinally. Fig.3 Perspective view of the machine showing the board lying transversally at the start of the film-removing eyele . Fig. Perspective detailed view of the slide used for de¬ taching edges of the protective film, seen in its idle position outside the machine. Fig.5 Detail of a cross-sec ion of the slide as it begins to approach the board. ^• Fig.6 Detail of a cross-sec ion of the slide while it is raising the edges of film from the board. Fig.7 Detail in perspective of the slide at the end of the translation movement during which edges of the protective film have been detached.

Fig.8 Detail in perspective of the slide when it has re¬ turned to its starting position once having detached the edges of the protective film from the board. Fig. Detail in perspective of the slide while detached edges of film are being raised.

Fig.10 Front view of the pair of pincers for detaching the protective film from the board, when in contact with said board . Fig.11 Detailed side view of the above pair of pincers in the act of touching the protective film.

Fig.12 Front view of the pair of pincers closed onto the edges of the protective film. Fig.13 Various stages in removal of the protective film being pulled off the board by the pincers, a dia- grammatic transversal view.

Fig.14 Side view of the pair of pincers, with diagrammatic indication of their position during removal of the protective film from the board and its discharge into containers . The machine 10 comprises the framework 11 on whose upper surface are arranged motor-driven rollers 12 for translation of boards 80 for making printed circuits, said boards being covered on both sides with protective film 8 I a nd 82. The fixed angular shoulder 20 is placed on the right of the machine close to the upper plane of rollers 12, said shoulder comprising the horizontal plate 21 and vertical wall 22. . At the left of the machine is the mobile angular shoulder 30 comprising the horizontal plate 31 and vertical wall 32, opposite the fixed shoulder 20.

Said mobile shoulder 30 can translate in the bars 33 thrust 5 by the pneumatic cylinder 34 (Fig. 3).

Immediately beyond the rollers 12, practically flush with the back end of the shoulders 20 and 30, there are para¬ llel rods 40 41, at a reciprocal distance one above the other so as to allow passage between them of the board 80 0 for printed circuits.

Immediately beyond said rods the articulated cross-piece 45 is placed close to the left side of the machine in the fulcrum point 46 (Fig. 4). Said cross-piece 45 is operated by the pneumatic cylinder 5 47 and, as required, can assume an upper end-stroke position on the horizontal trajectory of the board 80, or a lower one below said board.

Close to said cross-piece 45 lies the sensor 24 practically flush with the upper geometrical plane of the rollers 12.

0 The shoulder 20 has in it a slot 23 and from this protrudes the lever 24 with pressure head 25 worked by the pneumatic cylinder 26.

On the diagonal of the angle formed by the fixed shoulder 20 and the cross-piece 45 close to the upper geometrical 5 plane of the rollers 12, the pincer 90 (Figs. 1, 10, 11) is placed comprising an arm 19, and head 94 opening onto which is the nozzle 92 connected by means of tube 93 to a suet ion fan . In the pin 96 at the top of said head the jaw 95 is arti- Q culated, said jaw having a head 97 and posterior shank 98 connected to the piston of pneumatic cylinder 99 articulated on the arm 1 9 .

When the jaw 95 rotates round the pin 96, the head 97 comes in contact with the head 94 at the point of the nozzle 92. The arm 19 of the pincer 90 is fixed to the shaft of motor 18 supported by the structure 14 of the frame 11 of the machine (Figs. 1, 10).

A second pincer 90 is contraposed to pincer 90, symmetri¬ cally in relation to the tangential geometrical plane above the rollers 12, said second pincer being supported by an arm 19 fixed to the shaft of the electric motor 18 supported by the above mentioned structure 14.

Placed on the right of the machine close to the fixed shoul¬ der 20, the slide 50 moves over the bars 52 and 53 parallel to the rollers 12 and practically at the same level. The ends of said bars, projecting out from the machine, are connected at their ends by the fixed shoulder 58. Said slide 50 comprises a rear body 59 and front block 51 connected to the rear body by an L-shaped bar 57 onto which is fixed the axial pneumatic cylinder 55 whose piston is connected to the shoulder 58 by the oblong block 54.

On its side facing the machine the slide carries a pair of horizontal parallel rectangular plates 63 64 reciprocal at a short distance respectively at a slightly higher and a slightly lower level in relation to the boards for printed circuits to be placed one after another on the rollers 12. In said plates 63 64, close to their edge towards the front of the machine 10, are cut the openings 70 70' inside which the knurled contraposed wheels 71 71' freely turn on pins 72 72' lodged in seats 73 73' transversal to the trajec- tory of the slide 50.

The flat springs 67, fixed by washer 68 and screw 69 to the plate 63, cause the wheel 71 to press against the wheel 71' and, being preloaded, act on each of the two ends of the pin 72. The position of wheels 71 71' on the horizontal plane is such that, during movement of the slide 50, their trajectory passes by the front transversal edge of a board for printed circuits which, during functioning of the ma¬ chine, comes in contact with the cross-piece 45. Diagonally fixed by means of a clamp 75 on the edge of the plates 63 64 facing towards the back and inside of the ma- chine, is a pair of nozzles for compressed air, 77 78, con¬ nected by a tube (76) to a compressor.

A projecting head 60 is fixed to the L-shaped bar 57. Valves 61 62 acting on the tube that connects the air com¬ pressor to the nozzles 77 78, are fixed on the block 54 and lie on the trajectory of the above projecting head during movement of the slide 50. How the machine operates.

A board 80 for printed circuits, covered on both surfaces by a protective film 81 82, is laid on the rollers 12 and said rollers 12 guide said board through the two parallel rods 40 41 until it comes in contact with the cross-piece 45.

On perceiving the board, the sensor 2>4 brings into action the pneumatic cylinder 34 controlling the shoulder 30 which then draws the board 80 along transversally moving it towards the cross-piece 45 until it comes in contact with the fixed shoulder 20.

The sensor 43, laced on said shoulder , stops cylinder 34 and operates cylinder 26 which, by means of head 25, stops and holds the board 80 over the rollers 12 (Fig. 3). At the same time cylinder 47 on cross-piece 45, lowers the board. The cycle for removing the films 81 and 82 from the board 80 then begins .

The slide 50 moves from its resting position (Figs.1, 3 and .5) towards the board 80 thrust by the cylinder 55. By this movement plates 63 64 approach the board 80 (Fig.5), respectively above and below said board, causing the wheels 71 71' to pass over the inner edge of said board. Action of said wheels, pressed together by the springs 67 (Figs. 6 and 7) places a stress on the edges 81' and 82' of the films 81 and 82 such as to detach them from the board 80.

The slide then returns to its idle position (Fig. 8). This position having been reached the pincers 90 90 driven by motors 18 18 move above and below the sheet 80 as seen in Figures 10, 1 I and 12) .

At this point the head^'60 fixed to the slide 50 acts on valve 61 causing jets 15 16 of compressed air to blow from the nozzles 77 78 onto the edges 81' 82' of the films 81 82 while at the same time suction from nozzles 92 92 mounted on the heads 94 94 of the pincers 90 90 is created.

The simultaneous action on said edges 81' and 82' of com¬ pressed air on one side and suction from the other, lifts up said edges (Fig. I I) and causes them to adhere to the heads 94 94 at the point of the nozzles 92 92 until said nozzles are covered by said lifted edges.

This fluodynamic closure of the nozzles operates solenoids and then the cylinder 99 of pincer 90 overturning the jaw 95 so that the edge 81' of the film 81 is caught and held between the end 97 of the jaw and the head 94. The electric motor 18 starts up causing the arm 19 of the upper pincer 90 to rotate, said pincer then rising above the board 80 and pulling the edge 81' of the film 81 which, on passing round the bar 40, is gradually and completely pulled off the board 80, carried above the machine and then discharged at the side into a container.

Simultaneously with the upper pincer 90, the lower pincer 90 acts in the reverse direction and, worked by an elec¬ tric motor 18 , detaches the film 82 which, on passing round bar 41 is carried out below the plane of rollers 12 and dis¬ charged at the side outside the machine into the container awaiting it (Figs. 13, 14). Continuing its movement, the board,now free of upper and lower protective films, is transferred by the rollers 13 out from the upper plane of the machine towards the devices for its collection. During its outward movement the board passes over a sensor setting it off and causing it to operate the controls needed for returning to start-of-cycle conditions, namely, return of pincers 90 and 90 near to the plane over which the boards for printed circuits move, return of the shoulder 30 to the left of the machine, of the cross-piece 45 to its upper end-stroke position, and so on.

Claims

1. Machine (10) for removal of protective film (81 82) from boards (80) used for making printed circuits characterized in that it comprises devices (13, 20-22, 30-32, 24-26, 45-47) for automatically placing each board (80)in the right position on a plane of motor-driven rol¬ lers (12) and for discharging said board at the end of the operation, devices (50-55, 57-59, 60-64, 67-73, 71'-73', 75, 77, 78, 15, 16) for detaching and raising from the board (80) an edge (81' 82') of the protective films (81 82), devices 18-19 , 40, 41, 90, 90 , 92, 92 , 94-99, 94 -95 , 97 i 99 ) for gradually removing the films (81 82) acting on the raised edge (81' 82') and for discharging them in a special container.

2. Machine (10) as in claim 1, characterized in that the devices for detaching and rais¬ ing an edge (81' 82') of protective film (81 82) from the board (80) comprise a means (50-55, 57-59, 63, 64, 67-73, 71'-73') for detaching said edge, neutralizing adherence between the board (80) and the edge (81 82') of films (81) (82) and for creating spaces and points of discontinuity between said board and said edge and comprising a means (15 16 60-62 75 77 78) for raising the edge enabling it to be held by a pincer (90 90 ) and the like.

3. Machine (10) as in claim 2, characterized in that the means for detaching an edge (81') (82') of the film (81) (82) from the board (80) comprises a slide (50) translating parallel to the plane over which the board (80) moves fitted with a knurled wheel (71) (71') kept under pressure by a spring (67), while the slide is moving, against the edge (81') (82') of the film (81 ) (82) and turning freely round an axis transversal to the direc- tion of movement of the slide (50).

4. Machine ( 10) as in claim 2, characterized in that the means for raising the detached edge (81') (82') of the film (81) (82) comprises a jet ( 15) ( 16) of compressed air directed against the points of discontinuous adherence and the spaces between the edge (81') (82') of the film (81) (82) and the board (80).

5. Machine ( 10) as in claim 2, characterized in that the means for detaching an edge (81') (82') of the film (81) (82) from the board (80) comprise a U-shaped slide (50) , translating parallel to the plane on which the board (80) moves, said slide having a pair of contra¬ posed knurled wheels (71) (71') maintained in pressure against each other by a spring (67), said wheels turning freely round an axis transversal to the movement of the slide (50) and supported respectively by the one and the other parallel plates (63) (64) forming the U-shaped slide (50), the slide's trajectory being such as to determine progressive insertion of the board (80) inside it and the simultaneous action of the knurled wheels (71) (71¹) on the edges (81¹) (82') of the films (81) (82) applied to each face of the board (80), and therefore simultaneous removal of said edges (81') (82').

6. Machine ( 10) as in claim 1, characterized in that the devices for gradual removal of the film (81) (82) acting on the raised edge (81') (82') comprise a pincer (90) (90 ) composed of a jaw (95) and a head (94) (94 ) that, when the cycle for removing the film (81) (82) starts, move close in to the raised edge (81') (82') in a position substantially orthogonal to the board (80)_; there being placed on said head (94) (94 ) a nozzle (92) (92 ) connected to an air suction circuit (93), the effect of this suction being to cause the raised edge (81') (82') to adhere to the plane of the head (94) (94 ) and then to the mouth of the nozzle (92) (92 ) and,consequent 5 upon increased depression in the suction circuit (93), acti by a pneumatic cylinder (99) (99 ),connected to said suctio circuit (93), controlling closure of the pincer (90) (90 ) so that the edge of the film is held between the jaw (95) and the head (94) (94 ), said pincer (90) (90 ) being sup- ported by an arm (19) (19 ) fixed perpendicularly to the shaft of an electric motor (18) (18 ) which, when the pince (90) (90 ) has closed, starts to rotate thus pulling the film (81) (82) gradually detaching it from the board (80) and then transferring it to a container for collecting the film where, having reached it, the pincer (90) (90 ) opens allowing the film (81) (82) to fall into the container.

7. Machine (10) as in claim 6, characterized in- hat the pincer (90) is placed symmetrical¬ ly to another similar pincer (90 ) the two pincers (90) (90 ) acting as a pair, one on one film (81) and the other on the other film (82) on either side of the board (80), removal of the film (81) applied to the upper face and of the film (82) applied to the lower face of the board (80) , therefore taking place gradually and simultaneously, move- ment of one pincer (90) from a position near the board (80) taking place in an upward direction until the upper film (81) is completely removed, movement of the second pincer (90 ) from a position close to the board (80) taking place in a downward direction until the lower film (82) has been completely removed, movement of said pincers (90) (90 ) being continued until the removed film arrives over the container for removed film.

8. Machine (10) as in claim 1, characterized in that gradual removal of the film (81, 82) is made by slowly pulling the raised edge (81') (82') with a pincer (90)(90 ) causing the film (81) (82) to pass round a rod (40)(41) parallel to the board (80) and a short way from it, in a direction orthogonal to the plane of movement of the board (80), or else towards the side of the board (80) opposite to the raised edge (81)(82) so that the pulling force takes the board (80) in an orthogonal direction, or opposite to said pulling force, as the film (8l)(82) is gradually detached from said board (80).

9. Machine ( 10) as in claim 1, characterized in that the devices for automatically placing boards for printed circuits on the plane of motor-driven rollers ( 12) comprise a transversal shoulder (20) fixed on one side of said plane ( 12), a mobile shoulder ( 30)placed on the other side of said plane ( 12) translatable on spe¬ cial bars (33) in a direction parallel to the motor-driven rollers (12) and worked by a pneumatic cylinder, a cross- piece (45) rectangular in form and parallel to said rollers ( 12) oscillating on an end pin (46) and worked by a pneu¬ matic cylinder (47) between two end-stroke positions, an upper one that interferes with the movement of the board(80) and a lower one underneath the trajectory of said board(80), a pressure head (25) for holding the board (80) firmly on the roller plane ( 12) worked by a pneumatic cylinder (26), a sensor (43) by the fixed shoulder (20) at the same level as that of the board (80), a sensor (24) immediately below the plane of movement of the board (80) close to its front edge that comes in contact with the above-mentioned cross-piece (45), the motor-driven rollers (12), when operated, causing the board (80) to move on until its front end touches the oscillating cross-piece (45), the sensor (24),placed below the plane of movement of the board (80), on sens- ing said board causes the mobile shoulder (s0) to move and this transfers said board (80) till it comes in con¬ tact with the fixed shoulder (20), the sensor (43), placed on said shoulder, causing the mobile shoulder (30) to stop, operating the pressure head (25) which holds the board (80) at the position it has reached, lowering the oscillating cross-piece (45) to its lower end-str s,th initiating the cycle of movements that remove the films (81) (82) from the board (80).