FR2641511A1 - Automatic transfer installation with self-propelled carriages - Google Patents

Abstract

The installation comprises individual movable supports for products which are to undergo a series of operations at work stations which are at a distance from one another. According to the invention, these individual supports for the products 3 are self-propelled carriages 2, with an electric drive motor 40, provided to move along a track 1 provided with rails 25, 26 for supporting and guiding the carriages 2, and also including electrical conductors 28, 29 for powering the motors 40 of these carriages 2. The track 1 forms one or more closed loops servicing the work stations.

Description

"Automatic transfer installation to self-propelled trolleys"
The present invention relates to an automatic transfer installation, of the type comprising those of individual supports, in particular for products having to undergo a series of operations at workstations distant from each other, these individual supports being movable along a path passing in front of said work stations.

 In general, transfer facilities allow, in production workshops where products or parts must for example undergo successive machining operations at several work stations, to transport these parts or products from a work station to the next according to a predetermined path.

 The transfer installations belonging to the oldest design essentially consist of a conveyor belt along which the work stations are arranged. In the majority of cases, these stations are manual: at each station, an operator must unload the products of the transporter to deposit them in front of him and make them undergo the desired operations, and he must again deposit these products on the transporter to make them leave for the next station. Such installations have no support for the products, and while mobilizing a large workforce they have many drawbacks. In particular, an entire installation can be immobilized in the event of a breakdown of a mechanical element or in in the event of human failure, the operators being dependent on each other and having to handle weights which may be significant. This type of installation is very difficult to automate operations.

 The modern requirements imposed on industrial manufacturing, in particular the need to increase productivity, have led to the appearance of transfer facilities in which the products are individually linked to geometrically well-defined supports, commonly called pallets or even passable. The pallets are transferred from one station to the next according to a predetermined route, and they allow the situation of a product in the manufacturing cycle to be checked at all times. In addition, these pallets allow a certain desynchronization of the workstations with respect to each other, this by building up buffer stocks, and they allow the automation of operations.

The current practical achievements of these latest transfer installations call on conveyors, which ensure the movement of the pallets themselves supporting the products to be brought to the different workstations. The conveyors used are various types of endless belts or belts, chain or belt conveyors, roller conveyors, etc. In all cases, these are expensive installations, which can only provide an increase in productivity and automation of operations at the cost of great complexity in mechanical or electromechanical production due to the number of functions to be carried out. , while offering only limited flexibility. In particular, it is necessary to provide all of the following functions, which are essential for the use of pallets
- horizontal movement of pallets
- pallet stop at each manual or automatic workstation
- isolation of the pallets, for example by lifting, to carry out the operations planned at the work stations
- stop the following pallets, put them on hold
- organization of the flow of pallets according to basic working times
- at the end of the cycle, return of the pallets to their starting point, for the handling and transfer of new products.

The management of all these functions requires the installation of numerous detectors, at all phases of the movement of the pallets, as well as control by a programmable controller, and all this implementation makes it difficult to modify the operational cycle. Otherwise,
The immobilization of such transfer facilities remains long in the event of a mechanical or electrical fault. Finally, and this last drawback is not the least important, these installations suffer from a lack of accessibility to the products supported by the pallets, all the faces of the products not being accessible to undergo the operations to be carried out.

 The present invention aims to eliminate all of the above drawbacks, by providing an automatic transfer installation of different design, which can in particular be managed in a much more flexible and decentralized manner by using computerized solutions, while benefiting from a simplification. mechanical and of maximum reliability, this installation can be easily transformed or reconverted and allows the transfer of products or parts while leaving free a maximum number of faces of these products or parts.

 To this end, the invention essentially relates to an automatic transfer installation, of the type specified in the introduction, in which the individual supports for the products are self-propelled carriages, intended to move in a predetermined direction along a track. designed to support and guide these self-propelled carts.

 Thus, the transfer installation according to the invention mainly consists of a track which forms one or more closed loops for serving the work stations, and a plurality of self-propelled carriages moving freely and in a closed circuit along of the track, these carriages supporting the products or parts to be brought successively to the different workstations. The "self-propelled" nature of the trolleys eliminates all other drive devices, the path becoming a purely static part, and the configuration of these trolleys is much more favorable than that of current pallets to leave a maximum of free faces on the products transported. The track itself offers, between workstations, possibilities to build up a buffer stock of self-propelled carts, and therefore of transported products.

Each self-propelled cart advantageously comprises, in combination
a mechanical part ensuring the rolling and guiding functions on the track, as well as the support of the product or products to be brought to the work stations,
an electric motor connected by a transmission assembly to at least one rolling member which cooperates with the track, for driving the carriage along this track, and
- an electronic assembly, containing both a microcomputer system and the power electronics for controlling the electric motor.

 Preferably, each carriage comprises an electric drive motor of the "step by step" type, while the aforementioned rolling member is a pinion which engages with a fixed rack belonging to the track. The trolley thus has a drive system ensuring in a perfectly controlled manner the acceleration, advancement and braking of this trolley, for its movements between the workstations, as well as the immobilization of the trolley for its positioning at a work station or any other point on the track.

 According to a particular embodiment, the track has a generally L-shaped profile, with a base, and with a vertical wing, a first guide rail being carried by the base at a distance from the vertical wing and a second guide rail being provided on the upper edge of this vertical wing, while each self-propelled carriage is provided with two lower roller bearing blocks, rolling on the first rail, and two upper roller bearing blocks, rolling on second rail.

 For the electrical supply of the engine of the carriages, as well as of their electronic assembly, the track comprises at least two electrical conductors, with which cooperate. The wipers carried by the carriages. The track also advantageously comprises an additional sectioned electrical conductor with which other wipers carried by the self-propelled carriages cooperate, this additional conductor and these other wipers belonging to an "anti-collision" system having a safety function which consists in maintaining minimum spacing between two consecutive carriages, causing if necessary the stopping of a carriage which would dangerously approach the previous carriage.

 The anti-collision system more precisely comprises, in a particular embodiment, an electrical conductor carried by the track and divided into sections of length less than the distance separating two wipers which are carried by each of the self-propelled carriages and which cooperate with this conductor, two successive sections of said conductor being electrically connected to each other by an electrical circuit branch comprising at least one diode, one of the wipers carried by each carriage being connected to means which bring this wiper to a predetermined electrical potential while the other wiper is linked to means for detecting or measuring the electrical voltage collected on the latter wiper.

Anyway, the invention will be better understood, and other characteristics will be highlighted, with the aid of the description which follows, with reference to the appended schematic drawing representing, by way of nonlimiting examples, some forms of execution of this automatic transfer installation to self-propelled carriages
Figure I represents, seen in plan and very schematically, a section of track of a transfer installation according to the invention, with indication of two workstations
Figures 2 and 3 are views similar to Figure 1, illustrating variants relating to workstations
Figure 4 is a very schematic but more complete plan view of a transfer installation according to the invention, with multiple loops and with various types of work stations
Figure 5 shows in plan, more precisely, sections of track and a self-propelled trolley at the end of the line, with return
Figure 6 shows, in a similar manner to Figure 5, a main track and a section of parallel track, with means for transferring the carriages
Figure 7 illustrates a diversion from a main track to a secondary track
Figure 8 is a detailed view, in cross section, of the track and of a self-propelled trolley traveling on this track
Figure 9 is a vertical longitudinal sectional view of the carriage of Figure 8, traveling on the track
Figure 10 is a view in horizontal longitudinal section, corresponding to Figure 9
Figure 11 is a block diagram of an anti-collision system.

 Figures 1 to 4 show, very schematically, parts of an automatic transfer installation comprising a track 1 and self-propelled carriages 2 moving along the track 1 in an invariable direction indicated by an arrow F. The carriages 2 support products or parts 3, to bring them successively to workstations 4, 4 ′ or 4 "arranged along the track 1.

 Workstations 4 may appear, as shown in FIG. 1, "in series" on track I, which means that each self-propelled carriage 2 stops, at each station 4 of this type, opposite a operator or machine depending on whether it is a manual or automatic workstation; the carriage 2 considered remaining stopped on track 1, the planned operation is carried out on the product 3 remaining in place on this carriage 2, while the following carriages which approach the station 4 are stopped behind the carriage 2 considered.

 As illustrated in FIG. 2, 4 'workstations can also be "bypassed from product", which means that each self-propelled cart 2 arriving at the entrance to a 4' workstation of this type is unloaded of its product 3 by an appropriate mechanism, the operation being carried out at station 4 'on the product 3 separated from the carriage 2. This carriage 2 continues its path along the track 1 to take up the same product 3 or another product at leaving the station 4 ', and to bring this product 3 to the next station, which may be of the same type or another type.

 FIG. 3 illustrates a variant of the previous system, in which the workstations 4 "are presented in" carriage bypass ", that is to say that at each station 4" of this type the self-propelled carriages 2 are diverted from the main track I to a section of track 5 parallel and specific to the 4 "station, by means of an appropriate transfer mechanism, specified below. The section of track 5 may comprise, upstream of the work station 4" properly said, an area allowing the constitution of a buffer stock.

After execution of the operation provided at station 4 ", on the product 3 carried by each carriage 2, this carriage is again transferred with the product 3 to the main track 1, where it can leave for the next station.

Figure 4 shows how the above possibilities can be combined with each other, in an installation where track 1 forms several closed loops 6,7,8 serving 4,4 ', 4 "workstations belonging to the three types defined above This figure clearly shows that the realization of a complete installation requires track accessories adapted to the different types of situation encountered, the following figures show some typical examples of such track accessories.
Thus, FIG. 5 indicates a diversion at the end of the line, the purpose of which is to return the self-propelled carriages 2 on a return track 1 'parallel to the track 1 corresponding to the "outward" journey, this at the end of the line or 'end of a loop. The accessory performing this function is a short movable track element 9, rotatably mounted on 185 around a vertical axis 16 located at equal distance from the two track parts 1 and 1'.

 FIG. 6 shows the accessories which allow the self-propelled carriages 2 to pass from a main track 1 to a parallel section of track 5, and vice versa, in the case of a workstation in "carriage derivation" as defined more high. The transfers of the carriages 2 are provided here by movable track elements 11 and 12, of short length, linearly movable in a direction perpendicular to the track 1 and to the track section 5 along respective guides 13 and 14, these elements 11 and 12 can be inserted in interruptions 15 of the main track 1.

 FIG. 7 illustrates the derivation of self-propelled carriages 2 from a main track 1 to a secondary track 1 ", belonging for example to a loop. The transfer of the carts from one track I to the other 1", and vice versa, is here provided by movable track elements 16 and 17, which describe translational and rotational movements, therefore which somehow combine the two elementary displacements previously described.

 It should be noted that, in the examples shown in FIGS. 5 to 7, the self-propelled carriages 2 have been shown each supporting two products or parts 3 transferred simultaneously, which constitutes an advantageous variant of the simplest case in which each carriage 2 supports a unique product 3.

 Figure 8 shows the profile of channel I, in a particular embodiment obviously not limiting. Track 1 consists of profiled elements, of cross-section in the general shape of "L" with a base 18 and a vertical wing 19.

 The base 18 is in the form of a hollow horizontal beam, in which a tubular conduit 20 is formed allowing a supply of compressed air. Two "T" grooves 21 and 22 are provided under this base 18, for its attachment to consoles or other similar supports.

The vertical wing 19 has, on its outer face, two other fixing grooves 23 and 24.

 A first guide rail 25 for the carriages 2 is fixed in an "L:" groove located along the longitudinal edge of the base 18 remote from the wing 19. A second guide rail 26 for the same carriages 2 is fixed in a "U" groove provided along the upper edge of the wing 19. Another groove, formed at the base of the wing 19 on the inner side, receives a rack 27.

 The inner face of the wing 19 also has three longitudinal grooves, in which are mounted respectively three superposed electrical conductors 28, 29 and 30. The first two conductors 28 and 29, between which a constant potential difference is maintained, ensure the DC power supply to self-propelled carriages 2, from a central transformer and rectification station. The third electrical conductor 35 belongs to an "anti-collision" system which will be detailed below.

 In addition, the inner face of the wing 19 carries one or more optoelectronic reading heads or cards 31.

 With reference also to FIGS. 9 and 1, we will now describe in detail one of the self-propelled carriages 2, adapted to travel on track 1, an example of which has just been indicated. The carriage 2 has a housing 32, comprising in particular an upper face, a lateral face and two front faces, and serving as a support for four rolling blocks, namely two lower rolling blocks 33 and two upper rolling blocks 34.

 The lower bearing blocks 33 each comprise a roller 35 with a horizontal axis, rolling on the upper face of the first guide rail 25, and a roller 36 with a vertical axis, rolling on a side face of the first guide rail 25. The upper bearing blocks 34 each comprise a roller 37 of horizontal axis, rolling on the upper face of the second guide rail 26, and two rollers 38 and 39 of vertical axes, rolling on the two lateral faces of the second guide rail 26 .

 The carriage 2 comprises, inside the housing 32, an electric drive motor 40 of the "stepping" type, connected by a transmission assembly 41 to a pinion 42 of vertical axis, which comes into engagement with the fixed rack 27 of track 1.

 For the electrical supply of the motor 45 and of the other electrical or electronic members, the self-propelled carriage 2 is provided with two superimposed wipers 43 and 44, which slide on the supply conductors 28 and 29. Two other wipers 45 and 46, mounted on mobile supports such as that 47, one at the front and the other at the back of the carriage 2, as shown in FIG. 10, are applied to the third electrical conductor 30 and thus form part of the anti -collision.

 On the self-propelled carriage 2 are mounted electronic cards 48. containing both a microcomputer system (microprocessor, memories, inputs, outputs) and power electronics for controlling the electric motor 40. A battery 49 is connected to certain components of the electronic cards 48. These electronic cards 48 cooperate with the optoelectronic heads or reading cards 31 carried by the vertical wing 19 of channel 1, for a reciprocal transmission of information between the carriage 2 and the channel 1 or the personal work places.

 Mechanically, the housing 32 of the self-propelled carriage 2 obviously also provides support for the product or products 3 transferred, the performance of this function being variable depending on the nature of these products and being indicated roughly at 50 in FIG. 8. The housing 32 also supports, at the front, a probe 51 which serves as an anti-collision safety device of last resort, the electric drive motor 45 being provided with an electromagnetic brake connected directly to the probe 51.

Finally, Figure 11 explains more precisely the principle of the anti-collision system previously mentioned.
The electrical conductor 30 carried by the track, and forming part of this system, is divided into sections the length L of which is less than the distance D which separates the two wipers 45 and 46 carried by each self-propelled carriage from one another. 2 and cooperating with this conductor 30. Two successive sections of the conductor 30 are electrically connected to each other by a circuit branch 52, into which at least one diode 53 is inserted.

 The rear wiper 46 of each carriage 2 is connected to an electronic assembly, or even a simple passive electrical assembly, which brings this wiper 46 to a certain predetermined electrical potential U and causes a certain electrical current to flow in the line of diodes 53. The voltage drop across a diode 53 through which this current flows is constant and thus known, the previous section will have a U-E potential, the still previous section will have a U-2E potential, etc.

 The front wiper 45 of each carriage 2 is linked to means for detecting or measuring the electric voltage V collected on this wiper 45. Thus, considering a carriage 2 and the following carriage 2, the detection or measurement of the voltage V collected by the wiper 45 of this following carriage makes it possible to know the distance which separates it from the preceding carriage.

The electronics for controlling the electric motor 45 controls the speed of the carriage 2 as a function of the detection or measurement of the voltage V, in order to slow down or stop this carriage 2 in the event of dangerous approaching the carriage situated immediately in front of it. The complete stopping of a carriage 2, in the event that the risk of collision is close, can be done by a simple electrical device, such as a relay operating directly on the comparison of the voltage V with a predetermined value .

 It goes without saying that the invention is not limited to the sole embodiments of this automatic transfer installation with self-propelled carriages which have been described above, by way of illustrative examples it embraces, on the contrary, all variant embodiments and applications respecting the same principle. Thus, one would not depart from the scope of the invention by modifying the number and arrangement of the rollers in the rolling blocks 33 and 34 of the self-propelled carriages 2, or by replacing the "stepping" electric motor 40 of these carriages by a drive motor of another type.

Claims (10)

CLAIMS I. Automatic transfer installation, of the type comprising those of individual supports (2), in particular for products (3) having to undergo a series of operations at workstations (4,4 ', 4 ") distant from from each other, these individual supports (2) being movable along a path passing in front of said work stations (4,4 ', 4 "), characterized in that the individual supports for the products (3) are trolleys self-propelled (2), designed to move in a predetermined direction (F) along a track (1) designed to support and guide these self-propelled carriages (2).  2. Automatic installation for transfer to self-propelled carriages according to claim 1, characterized in that the track (1), on which the self-propelled carriages (2) circulate, forms one or more closed loops (6,7,8) serving the stations working (4,4 ', 4 ").  3. Automatic installation for transfer to self-propelled carriages according to claim 2, characterized in that the track (1), on which the self-propelled carriages (2) circulate, serves work stations (4) "in series" on this xoie ( 1), where each self-propelled carriage (2) stops on the track (1), the operation provided at these stations (4) being carried out on the product (3) remaining in place on the carriage (1).  4. Automatic installation for transfer to self-propelled carriages according to claim 2, characterized in that the track (1), on which the self-propelled carriages (2) circulate, serves workstations (4 ′) "in product bypass", where each self-propelled cart (2) is unloaded from its product (3) the operation provided at these stations (4 ') being carried out on the product (3) separated from the cart (2).  5. Automatic installation for transfer to self-propelled carriages according to claim 2, characterized in that the track (1), on which the self-propelled carriages (2) circulate, serves work stations (4 ") in" carriage bypass ", where the self-propelled carriages (2) are diverted from the main track (1) to a parallel section of track (5), specific to one of these stations (4 "), by transfer means (11 to 15).  6. Automatic transfer installation to self-propelled carriages according to any one of claims 1 to 5, characterized in that each self-propelled carriage (2) comprises, in combination  - a mechanical part (32 to 39, 5G) ensuring the rolling and guiding functions on the track (1), as well as the support of the product (s) (3) to be brought to the work stations (4,4 ', 4 "),  - an electric motor (4ru) connected by a transmission assembly (41) to at least one rolling member (42) which cooperates with the track (1), for driving the carriage (2) along this track (1 ), and  - An electronic assembly (48), containing both a microcomputer system and the power electronics for controlling the electric motor (40).  7. Automatic installation for transfer to self-propelled carriages according to claim 6, characterized in that each carriage (2) comprises an electric drive motor (qu,) of the "step by step" type, while the aforementioned rolling member is a pinion (42) which engages with a fixed rack (27) belonging to the track (1).  8. Automatic transfer installation to self-propelled carriages according to claim 6 or 7, characterized in that the track (1) has a profile in the general shape of "L", with a base (18) and with a vertical wing (19) , a first guide rail (25) being carried by the base (18), at a distance from the vertical wing (19) and a second guide rail (26) being provided on the upper edge of this vertical wing (19 ), while each self-propelled carriage (2) is provided with two lower bearing blocks (33) with rollers (35,36), rolling on the first rail (25), and two upper bearing blocks (34) with rollers (37,38,39), rolling on the second rail (26).  9. Automatic installation for transfer to self-propelled carriages according to any one of claims 6 to 8, characterized in that the track (1) comprises, for the electrical supply of the motor (40) self-propelled carriages (2), as well as of their electronic assembly (48), at least two electrical conductors (28,29) with which cooperate sliding shoes (43,44) carried by the carriages (2).  1u. Automatic transfer installation to self-propelled carriages according to claim 9, characterized in that the track (1) also comprises an additional sectioned electrical conductor (30) with which other wipers (45,46) carried by the self-propelled carriages (2) cooperate. ), this additional conductor (30) and these other wipers (45,46) belonging to an "anti-collision" system designed to maintain a minimum spacing between two consecutive carriages (2).  He. Automatic transfer system to self-propelled carriages according to claim 10, characterized in that the anti-collision system comprises an electrical conductor (30) carried by the track (1) and divided into sections of length (L) less than the distance (D ) separating two wipers (45,46) which are carried by each of the self-propelled carriages (2) and which cooperate with this conductor (3ru), two successive sections of said conductor (30) being electrically connected to each other by a circuit branch (52 ) comprising at least one diode (53), one of the wipers (46) carried by each carriage (2) being connected to means which bring this wiper (46) to a predetermined electrical potential (U) while the other wiper (45) is linked to means for detecting or measuring the electric voltage (V) collected on this wiper (45).  12. Automatic installation for transfer to self-propelled trolleys according to claim 10 or 11, characterized in that each self-propelled trolley (2) also comprises, at the front, a feeler (51) serving as anti-collision safety of last resort, the electric drive motor (4ru) of this carriage (2) being provided with an electromagnetic brake connected to said probe (51).  13. Automatic transfer installation to self-propelled carriages according to any one of claims 6 to 12, characterized in that the channel (1) carries optoelectronic reading heads or cards (31), with which the electronic assemblies cooperate - (48 ) self-propelled trolleys (2), for the reciprocal transmission of information between each trolley (2) and the track (1) or the work stations (4,4 ', 4 ").