FR2613336A1 - Assembly station with high-rate dispensing system - Google Patents

Abstract

Automatic assembly station having two parallel tracks 4', 4'' for supplying components at a gripping point P of a manipulator 14. The two tracks are articulated and may be displaced in order to end alternately at the said gripping point.

Description

ASSEMBLY STATION WITH HIGH-RATE DISTRIBUTION SYSTEM.

The invention relates to an automatic assembly station comprising a device for arranging and positioning a product, at a predetermined point, a manipulator with a component gripping member for transferring and depositing the latter at said predetermined point and a feeding device for presenting the components to said manipulator.

Automatic assembly workshops are increasingly faced with a problem of increasing production rates. conventional stations, on which the generation of movements is most often done by pneumatic means, hardly exceed rates of 1000 to 1200 cycles / hour, while certain current production levels would require two or three times more.

A conventional automatic assembly station is made up of three parts - A feeding and positioning device, the role of which is to place the product on which it is working in the correct position.

- A distribution device, the role of which is to present precisely the component to be inserted, generally from a bulk supply.

- A handling device, comprising a device capable of taking the component at the point where it is presented by the dispensing device and placing it on the product positioned by the supply and positioning device.

To obtain a given rate, it is obviously necessary that each of the three devices is capable of this rate, and that synchronization between them is ensured.

The present invention relates more particularly to the distribution function. In a very widespread way, this function is ensured by vibrating bowls. This well-known device consists of 1) A circular tank into which a certain quantity of bulk components is periodically poured out.

2) A mechanical generator imparting a vibration to the tank, resulting in the appearance of a rotational movement of all of the components contained therein 3) A helical ramp placed on the side wall of the tank, and whose pitch is provided so that the components, due to their rotational movements, tend to rise along this ramp and reach the edge of the tank. During their movements along the ramp, the components encounter a certain number of obstacles or mechanical traps intended either to modify their orientation, or to cause those which do not present themselves to fall to the bottom of the tank. Correctly oriented components are thus obtained at the upper end of the tank.

4) A linear track extending from the helical ramp. Along this track, the components circulate while being guided so as not to lose their orientation. The role of this track is on the one hand, to bring the components to the point of gripping by the manipulator and on the other hand, to provide an accumulation buffer allowing to ensure a regular supply of the manipulator, from a bowl flow which is him; very irregular.

The linear track is generally provided with an autonomous energy source, in particular a generator of vibrations or compressed air, ensuring the progression of the components.

Figure 1 shows such a device designated by the general reference 6, on which we recognize the tank 1, set in vibration by the mechanical generator 2. The components 5 travel in the direction of the arrow along the helical ramp 3, then along the linear track 4.

The throughput provided by such a device depends closely on the size and shape of the components to be dispensed. If these are small and simple in shape, this flow can be very high.

On the other hand, if they are large and of complex shape, it decreases sharply, and can become very insufficient compared to the need.

The object of the present invention is to allow a multiplication of the natural flow of a distribution by an integer factor. The description will be made with a factor of 2, but more important factors are also possible. In practice, however, a doubling of the natural flow is sufficient in most cases. The assembly station according to the present invention is characterized in that the supply device comprises at least two parallel tracks for movement of the components towards the manipulator capable of cooperating selectively or alternately with said two tracks for picking up the components and depositing them at said predetermined point and that the overall flow of the two tracks is at least equal to that of the manipulator, the flow of a single track being less than that of the manipulator.

The basic idea is to replace the linear track with two adjacent tracks. In a first embodiment of the invention, these tracks may be subject to a slight transverse movement allowing their downstream ends to come alternately at the location of the gripping point of the manipulator.

In another embodiment of the invention, the tracks are fixed, and it is the head of the manipulator which comprises a movable element by translation or rotation, allowing the gripping member to present itself alternately or selectively opposite of each of the tracks.

Other advantages and characteristics will emerge more clearly from the description which follows of an embodiment of the invention, given by way of nonlimiting example and represented in the appended drawings, in which: - Figure 1 is a plan view of a known vibrating bowl, for the assembly station according to the invention; - Figure 2 is a section along line 2-2 of Figure 1; - Figure 3 is a schematic plan view of an assembly station according to the invention; - Figure 4 is a schematic plan view of an alternative embodiment according to the invention of a manipulator gripping member; - Figure 5 is an operating table of the gripping member according to Figure 4; FIGS. 6 and 7 are schematic plan views of two variants of supplying the tracks according to FIG. 3.

The operation of the vibrating bowl according to Figures 1 1 and 2 is apparent from the preceding description.

In Figure 3 we see, in top view, two vibrating bowls 6 ', 6 "whose outputs in the form of tracks 4 are extended by tracks 4', 4" on which the components 5 travel in the direction of the arrow . The tracks 4 ', 4 "can pivot at a small angle around the fixed articulation points 8', 8".

They are also connected by a link 9 with which they constitute the joints 10 ', 10 ". The set of joints 8', 8", 10 ', 10 "constitutes a parallelogram allowing the tracks 4', 4 "to change position under the action of the jack 12 relayed by the link 11.

In FIG. 3, the system is pushed to the left by the jack 12, so that it is the end of the track 4 "which occurs at the gripping point P of the arm 13 of a manipulator 14. In the other position, this location is occupied by the end of the track 4 '. If the power supply to the actuator 12 is synchronized with the movement of the manipulator 14, it is easy to ensure that each track 4', 4 "is present alternately at point P, the movements being made while the manipulator 14 is going to deposit the component 5 which it has just grasped.

For clarity of the figure, the arm 13 of the manipulator has been interrupted above the end zone of the tracks 4 ', 4 ".

It is obvious that the flow of components 5 supplied to the manipulator 14 is shared between the two tracks 4 ′, 4 ", each of them having to ensure only half of this flow.

The kinematics of the system must be organized so that the component 5 arriving at the end of runway 4 ', 4 "is in exactly the same position, whether it is runway 4' or runway 4". For this purpose, the ends of the tracks may be slightly divergent so as to compensate for the rotational movement of the parallelogram.

The constructive provisions can obviously be different without departing from the scope of the invention. In particular, actuation by jack can be replaced by any other suitable means such as an electric motor or an electromagnet.

The manipulator 14, which can be of any type, automatically transfers the component 5 taken from the location P to a predetermined point M where a feeding device 15, in particular a conveyor, has brought a product 16 on which must be mounted the component 5. The manipulator 14 performs the assembly operation before returning to the initial position at location P for a new cycle. Meanwhile, product 16 leaves point M and the next product 16 is advanced to point M.

Another component 5 of track 4 ′ or 4 "is brought to point P. It is unnecessary to describe these transfer and assembly operations well known to specialists.

Referring to Figure 4 we see an alternative embodiment in which the manipulator 14 cooperates with two linear tracks 17 ', 17 "fixed arranged side by side.

The head 18 of the manipulator essentially consists of a slide block 19 fixed to the end of the movable arm 13. On the block 19 moves in translation a slide 20 carrying the gripping device 21, of a type known per se, such than a pneumatic or electromagnetic clamp.

The slide 20 is actuated by a jack 22 which allows it to take two positions P ', P ", corresponding respectively to the downstream ends of the tracks 17', 17". As for the removal position, it can correspond to one of these 2 positions of the slide 20, for example the position P '. The complete operating cycle is indicated by the table in FIG. 5. It can be seen that the removal is always done at P ', while the setting is made alternately at P' and P ". The displacements of the slide 20 are - From P 'to P "between phases 3 and 4 - From P" to P' between phases 4 and 1
These movements must be made in masked time while the head of the manipulator 1 4 is moving between the gripping positions P and the removal positions M.

The constructive provisions may be different without departing from the scope of the invention. In particular, the displacement by translation of the gripping device 21 can be replaced by a rotation, and the actuation by jack 22 can be replaced by another principle.

Regarding the distribution of the flow between the 2 tracks 17 ', 171', the result obtained is obviously the same as with the previous principle of the articulated tracks 4 ', 4 ".

For optimal operation, it is recommended to have presence sensors 23 ', 23 "allowing permanent control of the presence of components 5 at the end of tracks 4', 4" or 17 ', 17 ". are shown only in FIG. 3 under the references 23 ′, 23 ". Thanks to their judicious use, the general functioning of the system can be improved in various fields.

First, they can be used to control the movement of tracks 4 ', 4 "in the case of the device in FIG. 3.

Suppose indeed that we are tapping into track 4 '. It is possible to leave this track in service as long as the sensor 23 'does not detect an interruption in the arrival of the components 5. As soon as a single interruption is detected, we switch to track 4 ", which has had time to accumulate a certain number of components 5, and it remains there until these have not been exhausted. This limits the displacements of the tracks 4 ′, 4 ", and the mechanical fatigue which results therefrom. This advantage could also be partially obtained without using the sensors 23 ', 23 ", by programming the system so that it draws a certain number n of components 5 in track 4', then the same number in track 4", and so on alternately. The frequency of movement of the tracks is thus divided by n.

With the device of FIG. 4, these improvements are also possible, although less advantageous from the mechanical point of view, since they do not bring an overall reduction in the number of movements that the slide 20 must accomplish.

Secondly, the use of sensors 23 ′, 23 ″ allows an interesting improvement in the field of service continuity. It is indeed known that the distribution devices are not of perfect reliability, the presentation of the components 5 can be interrupted, in particular by jamming phenomena In a conventional distribution, this phenomenon results in the stopping of the work station, with corresponding loss of production.

In a 4 ', 4 "or 17', 17" multi-track system, the consequences of jamming can be significantly reduced.

If the system comprises for example 2 tracks 4 ′, 4 ", and if we admit that there is an interruption in the supply of track 4 ′, it is easy, as soon as this interruption is detected, by the corresponding sensor, to modify the operating sequence of the system so that track 4 "is the only one used until power is restored to track 4 '.

If we are in an embodiment corresponding to FIG. 3, it suffices to hold the actuator 12 in the "pushed" position in order to permanently leave the track 4 "opposite the gripping point P. If it is the track 4 "which is broken, the actuator 12 is kept in the" pulled "position so as to leave only track 4 'in service.

If we are in an embodiment corresponding to FIG. 5, a failure of track 17 'leads to making the movements of the slide 20 systematic, so as to only call on track 17 ". If it is the latter 17 ", which is broken down, the slide 20 is on the contrary permanently maintained in position P 'so as to stress only the track 17'.

The station can thus be kept in activity, albeit at a reduced rate. Note, however, that this reduction will generally be done in a ratio greater than 0.5, insofar as, in a correctly designed installation, the natural flow rate of the distribution must be greater than that of the manipulator 14. For example, if the rate of the manipulator 14 is 3000 cycles / hour, and if each track is capable of being supplied at the rate of 2000 components / hour, at full speed of the vibrating bowl 6, the rate of the station will only decrease in a ratio of 1.5 when one of the tracks is blocked.

A significantly improved regularity of operation is thus obtained, the improvement being even more significant if the number of tracks is higher.

Finally, if, by a combination of circumstances, the two tracks are in a blocking situation, the simultaneous information coming from the two sensors 23 ′, 23 ″ must cause the station to stop immediately.

The tracks 4 ', 4 ", 17', 17" can be fed from vibrating bowl devices 6, although other feeding principles are also possible without departing from the scope of the invention.

In the embodiments shown in FIGS. 6 and 7, the tracks 4 ′, 4 "are supplied by 2 separate vibrating bowls 6.

This principle does not pose any particular problem, but has the drawback of doubling the entire distribution infrastructure, as well as the resulting footprint.

In another embodiment, not shown, this drawback can be avoided by feeding the 2 tracks 4 ′ and 4 "from a single vibrating bowl equipped with two helical ramps opening out opposite each of the tracks 4 ′, 4", according to a technique known per se.

Claims (10)

1) Automatic assembly station comprising a device for feeding and positioning a product at a predetermined point (M), a manipulator (14) with a component gripping member (5) for transferring and depositing the latter at said point determined and a supply device for presenting the components to said manipulator, characterized in that the supply device comprises at least two parallel tracks (4 ′, 4 ") for movement of the components towards the manipulator capable of cooperating selectively or alternately with the said two tracks for taking the components and depositing them at said predetermined point and that the overall flow rate of the two tracks is at least equal to that of the manipulator, the flow rate of a single track being lower than that of the manipulator. 2) Station according to claim 1, characterized in that the manipulator (14) has a single gripping location (P) and that the downstream ends of said tracks (4 ', 4 ") are movable and capable of being moved for selectively or alternately coming to said gripping location. 3) Station according to claim 2, characterized in that each track (4 ', 4 ") has a section whose one end constitutes said downstream end of the track and whose other end is pivotally mounted, that the sections of different tracks extend substantially parallel and are connected by a control rod (9) to pivot together under the action of a control member (12) to supply the manipulator (14) selectively by one or the other said tracks. 4) Station according to claim 1, characterized in that said tracks (17 ', 17 ") are fixed, and in that the gripping member (21) of the manipulator is movable relative to the arm of the manipulator, in order to present themselves and cooperate selectively or alternately with each of said tracks, the position for depositing at said predetermined point being unique. 5) Station according to any one of the preceding claims, characterized in that each track is supplied by a particular supply device (6 ', 6 "), in particular with vibrating bowl. 6) Station according to claim 1,2,3 or 4 characterized in that all of the tracks are supplied by a single supply device. 7) A station according to claim 6, characterized in that the feed device is a vibrating bowl provided with as many helical ramps as there are tracks to be fed. 8) Station according to any one of the preceding claims, characterized in that the presence of components (5) is detected by sensors arranged at the end of each of the tracks, and that the passage from one track to another is done when the runway in use is exhausted. 9) Station according to any one of claims 1 to 7, characterized in that the tilting of a track (4 ', 4 ") on another is carried out systematically, but only after removal of a given amount of components on the same track. 10) Station according to any one of the preceding claims, characterized in that the operating sequence can be modified automatically in the event of a power failure of one of the tracks (4 ', 4 "), the system continuing to operate at a reduced rate by only using other tracks that are still powered