FR2700487A1 - Transport pallet for automised assembly line - Google Patents

Abstract

The pallet for transporting parts comprises a support plate (24) which has an internal suction chamber and holes (42) formed on an upper face (43) of the support plate, communicating with the internal chamber (34). The pallet comprises interchangeable (44,46,48) and removable parts adapted to be placed in the holes. These parts comprise prehensile suckers to assure the grasping of a part on the upper face of the plate.Valves (48) stop the holes not occupied by the prehension suckers and by the positioning parts.

Description

PALLET OF TRANSPORT OF MECHANICAL PARTS
AND AUTOMATED DIMENSIONAL CONTROL INSTALLATION
USING SUCH PALLETS.

DESCRIPTION
The invention relates mainly to a pallet designed to transport machined mechanical parts between different stations of an industrial installation, whatever the shape of the parts and the nature of the materials which constitute them, by guaranteeing a precise and reproducible positioning and orientation of the pieces on the pallet.

 The invention also relates to an application of such pallets to the transport of parts in a dimensional control installation.

 It will however be observed that transport pallets in accordance with the invention can be used in other industrial installations, without departing from the scope of the invention.

 The industrial installations in which the mechanical parts are machined, then the dimensional control of the machined parts, require precise knowledge of the position and orientation of the part on each of the machining and control machines.

 When one or more of these tasks must be carried out continuously and automatically, the parts are brought to the corresponding stations by transport pallets which are designed to ensure precise and reproducible positioning and orientation on the corresponding machine. The parts are mounted on the pallets, then unloaded therefrom in specific stations distinct from the machine in question and the transfer of the pallets between these stations and the machine is ensured by transfer means adapted to the particular configuration of the installation. .

 In such an installation ensuring the continuous and automatic execution of one or more tasks using appropriate machines, the positioning and orientation which are given to each of the parts on the pallets at the loading station determine the positioning and orientation of parts on machines.

This means that the positioning and orientation of the parts on the pallets must be known with good precision and in a reproducible manner.

 Given the importance of the forces which are transmitted to the part on most machining machines, the fixing of the parts on the pallets is generally carried out in this case using mechanical clamping means.

 However, the use of mechanical clamping means has significant drawbacks. Firstly, excessive tightening of these clamping means can lead to a deformation of the parts making them unacceptable, either for dimensional reasons or for aesthetic reasons. This deformation can also distort the task that the machine is performing, especially when it is a dimensional measurement.

 Furthermore, the size of the mechanical clamping means constitutes a notable drawback when performing certain tasks such as a three-dimensional control operation of the parts.

 Consequently, it appears desirable, in particular when the forces exerted on the part at the post under consideration are not too high, to have means of clamping the parts on the pallets eliminating any risk of excessive tightening of the parts and releasing as much as possible. space surrounding the rooms.

 Furthermore, it is also desirable that the means of clamping the pieces on the pallets preserve the independence and complete autonomy of the latter, that is to say that there is no permanent cable type connection. or flexible hose between the pallets and the rest of the installation.

 The subject of the invention is precisely a transport pallet, the original design of which enables it to grip parts of varying natures and dimensions in positions and with precise and known orientations, without risk of excessive clamping of the parts, largely freeing up the space surrounding them and without there being a permanent connection between the pallet and the rest of the installation.

 According to the invention, this result is obtained by means of a pallet for transporting parts, comprising a support plate, characterized in that the support plate has an interior chamber forming a vacuum reserve, and holes formed on an upper face. of the support plate, according to a regular network and communicating with the interior chamber, the pallet further comprising removable and interchangeable members capable of being placed indifferently in the holes, these members comprising gripping suction cups, capable of ensuring the gripping of the at least one part on said upper face under the effect of the vacuum prevailing in the interior chamber, positioning members capable of ensuring the positioning of this part, and shutters, capable of closing the holes not occupied by the gripping suction cups and by positioning members.

 According to a preferred embodiment of the invention, each of the gripping suction cups and each of the positioning members comprise a base capable of being received in each of the holes. In addition, each of the gripping suction cups comprises, between this base and a suction cup part, a three-way valve able to communicate this suction cup part either with a passage formed in the base and opening into the hole in which is received the 'base, either with the outside.

In this case, the holes and the bases advantageously have a circular section.

 In this same preferred embodiment of the invention, the holes are arranged in a square pitch network of n rows and m columns, each row and each column being assigned separate marks on the upper face of the plate, which allows a precise identification of each hole.

 So that the pallet can be positioned precisely on different devices or machines of the installation in which it is to be used, the tray advantageously comprises, on its underside, means for positioning and centering the pallet.

 In the preferred embodiment of the invention, the plate comprises a lower plate, the upper face of which has a central recess, an upper plate relatively thin compared to the lower plate, crossed by the holes and delimiting with the central recess said inner chamber, means for assembling the lower and upper plates, and sealing means interposed between these plates, around the central recess. In order to avoid any deformation of the upper plate, under the effect of the vacuum prevailing in the central recess, the latter is advantageously divided into several parts by perforated ribs on which the upper plate bears.

 In addition, so that the vacuum reserve formed by the interior chamber remains effective despite slight leaks which may occur between the parts and the gripping suction cups, the support plate is provided with means for automatically connecting the interior chamber to a source. external vacuum associated with one or more of the fixed and mobile stations of the installation.

The invention also relates to an automated installation, for the execution of at least one dimensional control operation on machined mechanical parts, comprising - at least one dimensional control machine - pallets for transporting the parts - a loading and unloading of pallets
and - means for transferring the pallets between the machine
and the various stations, characterized in that the transport pallets are produced in accordance with the invention.

 In a preferred embodiment, this installation further comprises a pallet management system, capable of receiving data relating to the references of the parts installed on the pallets at the positioning station, as well as to the position and orientation of the parts on these pallets, and able to restore these data to the control machine.

 To give the installation autonomy allowing it to operate for several hours in the absence of personnel at the pallet loading and unloading station, the installation also advantageously includes a storage station for loaded pallets, before checking the parts. .

A preferred embodiment of the invention will now be described, by way of nonlimiting example, with reference to the accompanying drawings, in which
- Figure 1 is a plan view schematically illustrating an automated three-dimensional control installation using transport pallets according to the invention
- Figure 2 is an exploded perspective view of a transport pallet according to the invention
- Figure 3 is a vertical sectional view illustrating on a larger scale a part of the transport pallet according to the invention as well as the various removable and interchangeable members of this pallet; and
FIG. 4 is a partial top view of the pallet illustrating the marks which can be worn on its upper face in order to identify each of the holes in which the removable and interchangeable members illustrated in FIG. 3 are received.

 The three-dimensional control installation illustrated in FIG. 1 firstly comprises a three-dimensional control machine of known type, designated by the reference 10. In the embodiment illustrated in FIG. 1, the table of this machine 10 comprises two locations 12, on each of which can be placed a pallet for transporting parts in accordance with the invention and the detailed description of which will be given below with reference to FIGS. 2 to 4. It will simply be observed at this stage of the description that each pallets is designed to support on its upper face one or more machined mechanical parts made of any material. These parts are positioned and oriented on the pallets with precision. Maintaining the position of the pallets on each of the locations 12 is itself ensured with precision by means which will also be described hereinafter.

 The installation illustrated in FIG. 1 further includes a pallet loading and unloading station, embodied in the embodiment illustrated in FIG. 1 by five locations on a roller conveyor 13. Four 14a of these locations are used for preparing the pallets, that is to say to load the parts to be checked on the pallets, while the fifth location 14b is reserved for loading the pallets by transfer means 20.

In the illustrated embodiment, the loading of the parts to be checked and the unloading of the checked parts are carried out manually by one or more persons placed at this station.

 Advantageously and as illustrated schematically at 16 in FIG. 1, the installation further comprises a computerized pallet management system.

This computerized pallet management system provides operators present at the loading and unloading stations with precise information concerning each of the parts to be checked. Thus, the computerized management system 16, which knows at all times the references of the mechanical parts machined awaiting inspection as well as their degree of urgency in the subsequent manufacturing process, provides the operator with the composition of the next pallet to be load, that is to say the references of the parts which it must mount on this pallet, as well as the relative positions of each part, thanks to a tracking system associated with each of the pallets, which will be described later.

 It should be noted that this information concerning the composition of a determined pallet remains stored in the computerized management system 16, so that it can be transmitted to the three-dimensional control machine 10, when the considered pallet is conveyed on one or more the other of the locations 12 of this machine in order to allow the control of the parts which it supports.

 When the control of the parts is carried out by the machine 10, the latter transmits to the computerized management system 16 the result of the measurements carried out on the parts, indicating either that all the dimensions checked are good, or that some of the dimensions checked are not good. When the controlled pallet returns to the loading and unloading station, the computerized management system 16 restores this information to the operator, so that the latter separates the acceptable parts from the unacceptable parts.

 In the embodiment illustrated in Figure 1, the installation further comprises a pallet storage station, materialized by locations 18 advantageously located on several superposed levels. Each of these locations 18 can receive a transport pallet loaded with parts to be checked, before this pallet is transferred to one of the locations 12 of the three-dimensional control machine 10.

This allows the installation to have a greater autonomy the greater the number of locations 18 occupied by pallets loaded with parts. Thanks to this arrangement, the installation can in particular operate at night to continue checking the parts located on the locations 18 of the storage station, while no personnel is present at the loading or unloading station.

 It should be noted that the autonomy thus conferred on the installation supposes that the locations 18 of the storage station can also receive the pallets after the parts have been checked.

 Finally, the three-dimensional control installation illustrated in FIG. 1 also includes the means 20 for transferring pallets between the locations 12 of the machine 10, the location 14 of the loading and unloading station and the locations 18 of the storage station .

 These transfer means 20 comprise a conveyor materialized by two parallel horizontal arms 22, capable of being placed under each of the transport pallets to remove it from the location it occupies and bring it to another location. To be able to carry out this movement, the conveyor materialized by the arms 22 has three degrees of freedom of translation and one degree of freedom of rotation. The three degrees of freedom of translation correspond to a vertical displacement of the conveyor perpendicular to the plane of FIG. 1 and to two horizontal displacements illustrated by the arrows F1 and F2 in this figure. The degree of freedom of rotation corresponds to a pivoting of the conveyor about a vertical axis, illustrated by the arrow F3 in FIG. 1. These different movements can be obtained by any mechanisms, well known to specialists.

 The movements of the pallets between the different locations 12, 14b and 18 using the conveyor materialized by the arms 22, as well as the implementation of the three-dimensional control machine 10 are controlled by the computerized management system 16 in the manner next.

 When the loading of a pallet is completed by the operator at any of the locations 14a, the operator transfers this pallet to the location 14b. The information is then transmitted to the computerized management system 16, which controls the transfer of this pallet from location 14b to a free location 18 of the storage station, using the conveyor materialized by the two arms 22.

 Furthermore, when the machine 10 indicates to the computerized management system 16 that it has finished checking the parts of a pallet, the management system commands the transporter to transfer this pallet from the location 12 considered to a location 18 free from the previously reserved storage station. The pallet is then transferred to location 14b of the loading and unloading station, on the operator's order, after checking the consistency of the measurement result.

On the contrary, in the event of inconsistency or messages of anomalies on the screen of the computerized management system 16, the pallet is brought back to the machine 10, to undergo a second measurement cycle.

 After the transfer of the controlled pallet to the storage station, the computerized management system 16 controls the transporter so that it goes to seek in the storage station materialized by the locations 18 the pallet whose control is most urgent, for the bring to location 12 thus freed.

 It should be noted that the presence of two locations 12 on the machine 10 allows the latter to work continuously, that is to say that the pieces of a pallet placed on one of the locations are checked while the carrier replaces the pallet placed on the other location 12.

 A preferred embodiment of the transport pallets which may be used in the installation of Figure 1 or in similar installations according to the invention will now be described, with more specific reference to Figures 2 to 4.

 The transport pallet according to the invention, generally designated by the reference 23 (Figure 3), mainly comprises a support plate 24, intended to be oriented horizontally. This support plate 24 comprises a lower plate 26 and an upper plate 28 relatively thin compared to the lower plate 26. These two plates are assembled at their periphery by screws 30, so as to constitute the support plate 24, which has in view from above the shape of a square in the embodiment shown. The dimensions of this square, as well as the thicknesses of the plates 26 and 28, depend on the dimensions and the nature of the parts to be transported.

 As shown in particular in FIGS. 2 and 3, the upper face of the lower plate 26 has, over most of its surface, with the exception of its periphery, a central recess 32, which delimits with the upper plate 28 a chamber interior 34 intended to form a vacuum reserve inside the support plate 24. As illustrated in particular in FIG. 2, the interior chamber 34 is divided into several compartments 34a by perforated ribs 36 which extend parallel to each other and at two of the sides formed by the support plate 24, at equal distance from each other. These ribs 36 are crossed by perforations 38 through which the different compartments 34a of the interior chamber 34 communicate with each other. These ribs 36 have the function of preventing the deformation of the upper plate 28 under the effect of the vacuum prevailing in the chamber 34 and the weight of the parts, in order to guarantee the accuracy of the measurements made on the latter.

 To preserve the tightness of the inner chamber 34 vis-à-vis the outside, a seal 40 is placed in a groove formed in the periphery of the upper face of the lower plate 26, around the recess central 32, so as to be in sealed contact with the lower face of the upper plate 28, when the plates 26 and 28 are assembled by the screws 30.

 The upper plate 28 is traversed by holes 42, of circular section, which open on the upper face 43 of the support plate 24, as well as in the inner chamber 34 forming a vacuum reserve. The holes 42 all have the same diameter and are arranged in a regular network, with square pitch, of n rows and m columns, as shown in particular in FIGS. 2 and 4.

In the embodiment illustrated in the figures, the number n of rows and the number m of the columns are identical.

 As illustrated more precisely in FIG. 3, the transport pallet 23 also comprises, in addition to the support plate 24, removable and interchangeable members intended to be placed indifferently in the holes 42. More precisely, three different types of gold removable and interchangeable can be placed in the holes 42. These three types of members are gripping suction cups 44, positioning members 46 and obturators 48.

 The gripping suction cups 44 comprise a cylindrical lower base 50, an intermediate portion 52 and an upper portion 54 forming a suction cup. The lower base 50 is a massive cylindrical piece whose lower end 50a, of smaller diameter, has a circular section identical to that of the holes 42 so that it can be placed indifferently in one or the other of these holes. An O-ring 56, placed in an annular groove in the shoulder separating the lower end 50a from the rest of the lower base 50 is then in contact with the upper face 43 of the support plate 24, so as to preserve the tightness of the interior chamber 34 forming a vacuum reserve with respect to the exterior.

The lower base 50 of each of the gripping suction cups 44 is further crossed along its axis and over its entire height by a passage 58.

 The intermediate part 52 of each of the gripping suction cups 44 is a mechanical part designed to be screwed to the upper end of the lower base 50. This mechanical part incorporates a three-way valve making it possible to communicate the upper part 54 forming a suction cup either with passage 58 either with the outside. The first position of the three-way valve ensures the depression of the upper part 54 forming a suction cup, by the vacuum prevailing in the inner chamber 34. It therefore ensures the gripping of a part P resting on the upper part 54 forming a suction cup. The second position of the three-way valve makes it possible to purge the upper part 54 forming a suction cup and, consequently, to release the part P.

 It should be noted that the transport pallet according to the invention may possibly include gripping suction cups 44 of different heights, in order to allow the transport of parts having a lower face in steps. These gripping suction cups then differ only in their lower bases 50, which have different heights.

 The positioning members 46 for their part comprise a lower base 60 and a cylindrical rod 62. The lower base 60 is practically identical to the lower base 50 of the gripping suction cups 44. It comprises in particular a lower end 60a, of reduced diameter , able to penetrate into any one of the holes 42, and an annular seal 64 which is then in leaktight support on the upper face 43 of the support plate 24. Unlike the lower bases 50, the lower bases 60 do not have no central passage.

 The lower part of each of the cylindrical rods 62 of the positioning members 46 is housed in a blind bore machined axially in the upper end of the lower base 60. The cylindrical rods 62 are therefore oriented vertically when the positioning members 46 are placed in holes 42 of the horizontal support plate 24. As illustrated in FIG. 3, the rods 62 extend upwards beyond the upper parts 54 forming the suction cup of the gripping suction cups 44, so as to form lateral stops ensuring precise positioning of the part P when the latter this rests on the gripping suction cups.

 Finally, the shutters 48 are members designed to plug the holes 42 of the support plate 24 not occupied by gripping suction cups 44 or by positioning members 46, so as to preserve the confinement of the interior chamber 34 forming a vacuum reserve. In the embodiment illustrated in Figure 3, the plugs 48 are made of flexible elastomer and they have a frustoconical shape. They thus ensure perfect sealing of the holes 42 in which they are placed, while presenting a space as limited as possible, above the support plate 24.

 As illustrated more specifically in FIG. 4, each of the holes 42 of the support plate 24 is identified on the upper face 43 of the latter by separate references 76, 78 assigned respectively to each of the rows and to each of the columns of the network. with square pitch formed by these holes. Thus and only as an example, the n lines of this network can be identified by the letters "A, B, C, etc." and the m columns of this network can be identified by numbers "1, 2, 3, etc.".

 This identification of each of the holes 42 formed on the support plate 24 constitutes positioning aid for an operator placed at the loading station of an installation such as that which has been described previously with reference to FIG. 1. More precisely, the computerized management system 16 of this installation determines in advance, as a function of the machined parts to be checked, the locations of the holes 42 in which the gripping suction cups 44 must be placed, the locations of the holes 42 in which the organs must be placed positioning 46 and the locations of the remaining holes 42, which must be closed by shutters 48. This information is made available to the operator, for example on a listing or on a screen, so that the positioning of these different members 44, 46 and 48 in the holes 42 can be carried out quickly by the operator with the help of the marks 76 and 78 por tees on the upper face 43 of the support plate.

 So that the positioning of the transport pallets 23 on one or other of the locations 12 of the three-dimensional control machine 10 and on the arms 22 of the conveyor 20 can be carried out with precision, the support plates 24 have on their face lower seven indentations 70 (Figure 3) machined in bosses 71a and 71b (Figure 2) which project into the inner chamber 34, without breaking the seal of the latter. Inserts 72 are placed in each of the cavities 70.

 When the transport pallet 23 is placed on one or other of the locations 12, three self-centering ball bearings 74 (FIG. 1) provided on these locations penetrate into three of the inserts 72 arranged in a triangle (in the bosses 71a of the Figure 2), which ensures precise positioning and orientation of the pallet and therefore contributes to the accuracy of the measurements made by the three-dimensional control machine 10.

 When the transport pallet 23 is placed on the transport arms 22, four self-centering ball stops 76 (FIG. 1) associated with these arms penetrate into the other four inserts 72 arranged substantially at the four corners of the pallet (in passages 71b in Figure 2). In addition, a suction cup (not shown), placed between the arms of the conveyor 20, comes into contact with the underside of its pallet, to avoid slippage thereof.

 Finally, it can be seen in FIG. 3 that the support plate 24 is equipped on its underside with at least one automatic male connector 78 opening into the interior chamber 34. The male automatic connector 78 is provided internally with a valve (not shown ) normally closed when this male connector is not engaged in a female connector.

 As illustrated in FIG. 1, each of the locations 12 of the control station comprises a female automatic connector 80, to which the male connector 78 is connected when a transport pallet 23 is brought to this location. Each female connector 80 is also equipped with a normally closed valve and it communicates with a vacuum source (not shown).

 A female automatic connector 82, 84 is also provided on the transport 20 and at each of the locations 18 of the storage station. Each connector 82, 84 is also equipped with a normally closed valve and connected to a vacuum source. The vacuum source of the storage station is illustrated at 86 in FIG. 1.

 Similarly, the operator has at the loading and unloading station materialized by the locations 14a of female connectors (not shown), equipped with normally closed valves and connected to a vacuum source by flexible pipes.

 This arrangement makes it possible to communicate the interior chamber 34 of each of the pallets 23 with a source of vacuum when the transport pallet is located on the conveyor 20 or on any one of the locations 12, 14a and 18, that is to say - say either on the three-dimensional control machine 10, or at the loading and unloading station, or at the storage station. This characteristic makes it possible to maintain the vacuum in the interior chamber 34 at a level sufficient to guarantee effective gripping of the part or parts carried by each of the pallets, taking into account the inevitable slight leaks between the gripping suction cups 44 and the parts. In addition, the autonomy of the pallets is preserved.

 The foregoing description shows that the transport pallets according to the invention have numerous advantages over the state of the art. In particular, gripping the parts by vacuum prevents damage or deformation thereof, which guarantees the quality of the parts checked and the effectiveness of the control. The technique described also makes it possible to very largely free up the volume surrounding the parts supported by the pallets, which greatly facilitates the execution of tasks such as the three-dimensional control of these parts. In addition, the arrangement of the transport pallets according to the invention has great flexibility and allows the gripping of one or more parts of different shapes and dimensions, whatever the nature of these parts and in particular the material which Finally, the transport pallets according to the invention have complete autonomy during their movements, which makes it possible to use them in installations having a varied architecture.

 It should be noted that the preferred embodiment which has just been described by way of example may undergo different variants without departing from the scope of the invention.

Thus, instead of being arranged in a square pitch network, the holes 42 could be arranged in a network of different shape such as a triangular pitch network.

Furthermore, it will be readily understood that the application which has been described by way of example with reference to FIG. 1 should not be considered as limiting. In particular, the transport pallets according to the invention can be used in an installation comprising several machines in front of which the parts must scroll successively and the presence of a storage station can be avoided if the operation of the installation in the absence personnel is not envisaged.

Claims (12)

 1. Pallet for transporting parts, comprising a support plate (24), characterized in that the support plate comprises an interior chamber (34) forming a vacuum reserve, and holes (42) formed on an upper face (43) of the support plate, according to a regular network and communicating with the interior chamber, the pallet further comprising removable and interchangeable members (44,46,48) able to be placed indifferently in the holes, these members comprising gripping suction cups (44 ), capable of gripping at least one part on said upper face under the effect of the vacuum prevailing in the interior chamber, positioning members (46) capable of ensuring the positioning of this part, and shutters (48 ), suitable for closing the holes not occupied by the gripping suction cups and by the positioning members.  2. Pallet according to claim 1, characterized in that each of the gripping suction cups (44) and each of the positioning members (48) have a base (50,60) capable of being received in each of the holes (42).  3. Pallet according to claim 2, characterized in that each of the gripping suction cups comprises, between said base (50) and a suction cup part (54), a three-way valve (52) capable of communicating this suction cup part either with a passage (58) formed in the base (50) and opening into the hole (42) in which the latter is received, or with the outside.  4. Pallet according to any one of claims 2 and 3, characterized in that the holes (42) and the bases (50,60) have the same circular section.  5. Pallet according to any one of the preceding claims, characterized in that the holes (42) are arranged in a square pitch network of n rows and m columns, each row and each column being assigned separate marks (76 , 78) on the upper face (43) of the plate.  6. Pallet according to any one of the preceding claims, characterized in that the plate (24) comprises, on its lower face, means for positioning and centering (70, 72) of the pallet on at least one external device (10.20).  7. Pallet according to any one of the preceding claims, characterized in that the plate (24) comprises a lower plate (26) whose upper face has a central recess (32), an upper plate (28) relatively thin by relative to the lower plate, crossed by said holes and delimiting, with the central recess, said inner chamber (34), means of assembly (30) of the lower and upper plates, and sealing means (40) interposed between these plates, around the central recess.  8. Pallet according to claim 7, characterized in that the interior chamber (34) is divided into several compartments (34a) by perforated ribs (36) on which the upper plate (28) bears.  9. Pallet according to any one of the preceding claims, characterized in that the support plate (24) is provided with automatic connection means (78) of the inner chamber (34) to an external vacuum source.  10. Automated installation, for the execution of at least one dimensional control operation on machined mechanical parts, comprising - at least one dimensional control machine (10) - transport pallets (23) of the parts - a loading and unloading of pallets  and - means for transferring (20) pallets between the ma  china and the various stations characterized in that the transport pallets (23) are produced according to any one of the preceding claims.  11. Installation according to claim 10, characterized in that it further comprises a management system (16) of the pallets (23), capable of receiving data relating to the references of the parts installed on the pallets at the loading station, as well as the position and orientation of the parts on these pallets, and capable of restoring these data to the control machine (10).  12. Installation according to any one of claims 10 and 11, characterized in that it further comprises a storage station (18) of pallets loaded with parts.