TECHNICAL FIELD

The present invention relates to a pickup head for a component assembly machine, in particular an assembly machine for the automatic mounting of electronic and similar components.

BACKGROUND

Automatic assembly machines for electronic components conventionally has a pickup head, which fetches electronic components from different magazines and mounts them on accurately determined locations on a circuit board. The transport from a magazine requires always a certain amount of time. Different suggestions have been made earlier and have also been implemented in present machines in order to reduce this amount of time, which can be in particular troublesome and result in the assembly operation requiring a long time in the case where many components are to be mounted on each circuit board and the pickup head can only transport one component in a movement from a magazine to the board.

In IBM Technical Disclosure Bulletin, vol. 28, No. 11 , April 1986, pp. 4764 - 4765, "Chip Transfer Head with Programmable Probe Centerlines", a chip transfer head is disclosed for transferring multiple chips from one type of device carrier to another type of device carrier. Four vacuum probes are used and their lateral position in relation to each other can be adjusted. Also, one or more of the probes can be retracted by means of a miniature air cylinders if all probes are not needed.

In IBM Technical Disclosure Bulletin, vol. 17, No. 7, December 1974, pp. 1876 - 1877, L.G. Call et al., "Electronic Component Assembly Apparatus", a single multisection ram is disclosed, having four independent sections. A selector block's slide is engageable in adjacent ram sections. The selected ram sections can be moved vertically by means of an operating cylinder. The ram sections can only selected in some limited patterns and are thus not controlled individually.

In IBM Technical Disclosure Bulletin, vol. 22, No. 7, December 1979, pp. 2757 - 2761, K.G. Hoebener, "Multiple Size Chip Pickup, Orientation and Placement Station", a chip placement station is disclosed having a transfer arm. To fixed locations on the transfer arm probes are attached, two for transfer of chips from delivery stations to orienting stations and one from an orienting station to station holding a substrate. The transfer arm moves the probes as one unit in one horizontal direction and in a vertical direction.

In Swedish Patent Applications SE-A 8203546-0, corresponding to U.S. patent application having serial number /271835, and SE-A 8203511-4, corresponding to U.S. patent application having serial number /271836, both filed June 9, 1981 for H.L. Wright et al. and assigned to USM Corporation, apparatus is disclosed for mounting components individually selected from magazines. Two pickup devices are movable independently along a front side and a rear side of vertically arranged magazines.

The U.S. patent US-A 4,951 ,383 and the European patent application EP-A2 0 373

373, for which convention priority is claimed from the same three Japanese patent applications, disclose an automatic mounting apparatus comprising a pickup head 10 having three or more vertically movable pickup devices 41 , each one having a vacuum nozzle 45 (11). The pickup devices comprise vacuum channels for holding the nozzle and the component to be mounted, and are driven vertically (z-direction) by a drive mechanism 43, consisting of a drive motor 67, a ball screw 68, a vertically movable nut 69 and a movable plate 70 connected to the nut and having a number of engagement pins 71. When the motor 67 is activated, the plate 70 is driven vertically (along guides 72), which in turn drives the pickup devices vertically by means of the pins 71 supporting the lower sides of flanges 54 mounted to the pickup devices. The pickup devices are further locked in an upper position by blocking levers 63 which are controlled by solenoids 65 and in a deenergized state thereof are locked, these means then engaging also the lower sides of the flanges 54 of the pickup devices. In the energized state, the pickup devices are free to move and will then rest on the support pins 71. The pickup head can then, by being driven by a single motor, individually and selectively control the pickup devices for picking simultaneously a number of components. Furthermore, the pickup devices can be also individually controlled to be turned to a desired angular position by means of individual drive motors 77, that are each one coupled to an own pickup device.

The Japanese patent application JP-A 6-37486 discloses an automatic assembly machine comprising a number of pickup devices. In e.g Figure 14 a pickup head is illustrated comprising at least two pickup devices 14 having vacuum nozzles, which devices seem to be spring-loaded (41) to a projected, lower position, and to be locked in an upper position by the operation of locking arms 44, which however are not individually operative. A similar machine is disclosed in the Japanese patent application JP-A 4-241499.

The Japanese patent application JP-A 64-2400 discloses a mounting machine comprising a pickup head having a number of spring-loaded (33) pickup devices locked in an upper position by blocking arms 36. One arm at a time can be operated for un-locking a selected pickup head.

The European patent application EP-A1 0 434 156 discloses a pickup head for e.g. an assembly machine comprising a number of pickup devices 3 which are mounted in parallel and can be driven to desired angular positions by means of crank arms 13, a coupling rod 15 and a single drive motor 36. Each pickup device can be driven individually to pick or place a component.

The Japanese patent applications JP-A 6-177 592 and JP-A 6-61692 and the European patent application EP-A1 0 578 136 also disclose assembly machines having pickup devices which in some cases appear to be individually operative.

SUMMARY

It is an object of the invention to provide a pickup head for an automatic component assembly machine, by means of which the mounting times can be reduced.

It is a further object of the invention to provide a pickup head having individual pickup devices, the movements of which can be obtained with few driving motors.

It is a further object of the invention to provide a multi-component pickup head having a low weight and a simple construction, allowing rapid movements of the pickup head.

It is a further object of the invention to provide an automatic component assembly machine, by means of which the total time for mounting components on a circuit board can be considerably reduced.

These objects are achieved by the invention, the characteristics of which are set out in and the scope of which is defined by the appended claims.

In a pickup head for an automatic component assembly machine a first part or house is provided, which by means of a driving motor and a transmission is movable in a vertical direction and is arranged on a wagon or frame which is movable horizontally, in the preferred case in one direction. The house carries several pickup devices, which are movably mounted in the house and in a movement of the house can be made to selectively accompany the house in order to pick components. Therefor, the pickup devices are individually resiliently biassed or urged to a lowered, extended position and further, they can be individually locked in an upper position by activating locking devices. They can be solenoids having locking pins, which at activation of the solenoids, will engage abutments of each pickup device. Hereby, the pickup head can driven by one single motor to simultaneously pick several components, what provides a quick picking function and thus a faster mounting.

The house has in an advantageous embodiment a frame shape comprising an upper portion or upper bar and a lower portion or lower bar, so that the pickup devices are movably or slidably mounted in these two portions. The elastic means acting on the pickup devices can then be mounted between the upper and the lower portions.

Further, when mounting a component a pickup device can be turned to a desired angular position by activation of another driving motor. From this, a single transmission device extends simultaneously to engagement devices on all pickup devices. The transmission device can comprise an endless element such as a toothed belt, which passes around a drive wheel of the driving motor and cooperates with suitably shaped wheels such as toothed wheels on the pickup devices. In this manner, an angular adjustment is obtained by means of one single driving motor acting on all pickup devices. The engagement devices can be slidable on the pickup devices in order to transmit such a turning movement, only when a pickup device adopts a certain position.

Thus, the two operating motors can be attached to the frame of the head allowing that the weight of the vertically moving parts, the house and the pickup devices, can be kept low.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be described in more detail with reference to a non-limiting embodiment and the accompanying drawings, in which:

- Fig. 1 is a front view of a pickup head for an automatic component assembly

machine,

- Fig. 2 is a sectional view along the line II-II in Fig. 1 and

- Fig. 3 is a perspective view of a component assembly device. DETAILED DESCRIPTION

In Fig. 1 a pickup head or component retaining head 1 is shown attached to the front side of the x-wagon 3 of an automatic assembly machine for electronic components. The x- wagon 3 is movable in a horizontal direction or the x-direction along a guide, see below. The pickup head 1 comprises a frame shaped house 5, which thus has an upper rod- or bar-shaped portion, a rod- or bar-shaped lower portion and two rod- or bar-shaped side portions, a rectangular opening being formed centrally in the house. The lower frame portion has a larger vertical width than the upper portion. The house 5 is movable in a vertical direction or the z-direction in relation to the wagon 1 and is therefor mounted in linear guides 7 attached to the x-wagon on both sides of the head 5. The guides 7 cooperate with guide wheels 9 rotatably attached to the side portions of the house 5.

In the house 5 several, for instance at most sixteen or as in the case shown eight pickup devices or pipettes 11 are provided. They consist of tubular parts, which each, through controllable valves 14, at their upper ends through hoses 13 are connected to a common vacuum conduit 15, the valves and conduit being arranged on a support 17 attached to the x- wagon 1. The pickup devices 11 are movable in the z-direction or vertical direction in relation to the house 5 by being mounted in coaxial bores in the lower and upper bar of the frame shaped house 5. Further, they are resiliently biassed, to lower, pressed down positions, so that they rest in these normal, lower positions with abutments 19 engaging the top side of the upper bar of the frame-shaped house 5. In Fig. 1 , only the pipettes having the order numbers 4 and 6 as counted from the left hand side are in this normal, pressed-down or protruded position.

The abutments 19 can as shown in the figures be arranged as flanges secured to the pickup devices at the upper portion thereof, at the connection of the vacuum hose 13 with the upper portion of the pickup devices 11. The elastic operation is achieved in the embodiment shown by helical compression springs 21 arranged between the underside of the upper bar of the frame-shaped house 5 and an abutment 23 having the shape of a ring or flange secured to the pickup devices 11 at portions thereof located inside the opening in the house 5, between the upper and lower bearings for the pickup devices. Other possible devices for obtaining an elastic operation can comprise suitably applied tension springs, gas or fluid springs, etc. The length of stroke of a spring and hereby its stiffness can be fixed or adjustable, such as for instance in the showed embodiment by means of a displacement upwards or downwards of the ring shaped abutment 23 of the pickup device 11 along the stem thereof, possibly also automatically adjustable by means of suitable devices, not shown.

The house 5 is moved in the z-direction by means of a servo control comprising a servo motor 25 having associated transmission means, in the embodiment shown consisting of a belt

27, for instance a toothed belt, secured to the house 5 at for instance its upper and lower frame parts and running over a pulley 29 attached to the shaft of the servo motor 25. The transmission can of course also in the conventional way be implemented by means of gear wheel - gear rack, chain - chain wheel, etc. Another possibility is to use a linear servo motor instead, which then simplifies the transmission.

For each of the pickup devices 11 there is a locking device, which is fixedly mounted to the x-wagon 3 and which in the embodiment shown comprises a solenoid 31. It is secured to a bent part 33, which is attached to a support 35, that in turn is attached to the x-carriage 3. The solenoid 31 operates for different electric excitation a pin 37 on its armature, not shown, so that this pin protrudes differently far from the body of the solenoid. In an extended or advanced position, the pin 37 can thus be applied under an abutment of the pickup device, such as for instance as in the embodiment shown, beneath the abutment 23 also used for supporting the spring 21. Hence, when the pin 37 is extended and thus the locking device is activated, the vertical movement of the pickup device is prevented in relation to the x-wagon 3. The locking device can also alternatively be implemented as a fluid operated cylinder or the like.

Further, the pickup devices 11 are also mounted so that they are rotatable around their longitudinal axis, i.e. in the φ-direction. They can all be turned an accurately controlled angle. Thus a servo motor 39 is attached to the house 5 having its drive shaft mounted in a vertical direction. Over a toothed wheel 41 stiffly mounted to the drive shaft runs a toothed belt 43, which cooperates with toothed pulleys or wheels 45 on each of the pickup devices 11. The toothed pulleys 45 e the shape of rather thin sleeves and are displaceable or slidable along a portion of the pickup devices 11 but are rotatably secured thereto by some suitable mechanical connection, comprising splines, wedge devices or the like and schematically indicated at 46. This rotatable stiff connection can alternatively be designed so that it is only effective when the pipettes 11 are in their normal, projected positions, and when they are in their upper positions, the connection can be allowed to be disengaged. In the first embodiment, all of the pickup devices 11 will simultaneously be turned through the same angle independently of their position or order number in the row, and in the other embodiment, only the lowered pickup devices are simultaneously turned at an activation of the associated servo motor 39 arranged for the turning operation.

Instead of a toothed belt, a stiff toothed element such as a gear rack, not shown, can be used for turning the pipettes 11. Such a gear rack must be mounted for a sliding movement in a direction perpendicular to the longitudinal direction of the pipettes 11 and for engagement with a gear of the servo motor 39 and with pulleys 45 having suitable teeth on the pipettes 11.

The function of the pickup head 1 will now be described. The house 5 of the pickup head is in its initial position in a pulled up position, above the position shown in the figures, having all the individual pickup devices 11 in their lowered, projected positions and so high

that the locking means of the lock devices, the pins 37, can be moved out to the lock abutments, here the abutments 23, in order to block the downward movement of the pickup devices 11. Suitably chosen lock devices are activated, in the case shown in Fig. 1 , the lock devices for all pipettes except those having numbers 4 and 6, and then the house 5 is moved in a downward direction by activation of the servo motor 25 for the movement in the z- direction. Hereby, the activated lock devices will engage their respective pickup device 11, i.e. the protruding locking pins 37 will engage a suitable surface of the abutments 19, for instance their under side, and the pipettes 11 , the lock devices of which have been activated, remain in this position. This is possible due to the elastic action of the compression springs 21 , which during the continued downward movement of the house 5 will be increasingly compressed.

The pickup devices 11 , the locking devices of which have not been activated, are moved downwards together with the house 5 and will in a pulled down position come into engagement with components, not shown, placed in suitable magazines, not shown. Through vacuum action the components are positively sucked to the lower, surfaces of the pipettes 11 , which have suitable nozzles, and then the whole house is again moved back and upwards. In a suitable high position, where the lock means of the lock devices can again engage all the pickup devices 11 , the x-wagon 3 is then moved to a suitable position in the x-direction above a circuit board. Here all the lock devices but one are activated for a selected pickup device and the house 5 is again lowered. For all pickup devices 11 but the selected one, their lock devices will be engaged so that they remain in an upper blocked position. The selected pickup device, however, follows the house 5 and the components retained thereby is placed on the circuit board. The valve 14 is operated in order to remove the negative pressure in this pipette, which releases the component, so that it can remain in its obtained position. After this the house 5 is transported to its upper position by activation of the z-servo motor 25 and the above described steps are repeated for all the pipettes 11 , which carry a component at their bottom surface. This means that all the locking devices but one are activated in the same manner as above and simultaneously the x-wagon 3 is moved to a new position in the x- direction, the house 5 is moved downwards, etc.

Before the contact between a component retained by a pickup device 11 and the circuit board, the pickup device and hereby the components can be turned to a suitable angular position by energizing the servo motor 39 for the movement in the ^-direction. The toothed belt 43 is hereby displaced a suitable distance and turns in the first case all the pipettes 11 , including those which are locked in their upper position, and in the second case only the protruding, lowered pipette 11, through the engagement between the belt 43 and the outer teeth of the toothed rings 45 and between splines or some wedge device inside the rings 45 and outside the pickup devices 11. This rotational adjustment can be necessary in order for the component to be placed in a correct position on the circuit board.

In Fig. 3 a component assembly or pick-and-place machine is illustrated in a

perspective view showing the general configuration of such a machine. A wagon or pickup head 301 is movable along a horizontal bar 303 to different locations, such as above magazine sites 305 intended to hold component feeders, which are movable in a horizontal direction perpendicular to the guide bar 303 and above a circuit board 307 retained on a slide, also movable in the same direction as the magazine sites 305. The wagon 301 carries the vertically movable house 5.