GB2154351A - Coding workpiece carriers in production plant - Google Patents

Abstract

Workpiece carriers (4) are fed to successive work stations (2) along conveyor tracks (13) at which stations (2) work operations are performed on individual parts (5) on the carrier (4) and in which a defect signal is allocated when appropriate. After a work operation has been performed a coding member (22) is left in a normal switching position corresponding to a defect coding or displaced into a switching position corresponding to an accept coding if the work operations performed were satisfactory. In a coding device displaceable coding elements (22) are supported by a workpiece carrier (4) and traverse a detector device (10) at the work processing station (2) and a switching element (10) for displacing the coding element (22) from a reject coding switch position to an accept coding switch position. An accept coding is consequently secured only by a deliberate action when satisfactory work processing has been completed and thus subsequent processing of defective parts is avoided simply and with great reliability. <IMAGE>

Description

SPECIFICATION Method of and a device for coding workpiece carriers in a production plant The invention relates to a method and a device for the coding of workpiece carriers in production plants, in particular for assembly of workpieces comprising several separate parts, in which the workpiece carriers are fed along conveying tracks to different successive operating or processing stations in which separate parts are added or fitted to or processed and wherein an error signal is allocated to a workpiece carrier receiving such workpieces in case of faulty assembling or processing, and these workpieces no longer being processed in the following working or processing stations or being supplied to a delivery point for scrap parts or for postprocessing.

Different coding devices for workpiece carriers in production plants are already known.

Devices of this kind commonly comprise signal carriers arranged on the workpiece carrier, e.g. pivotable or displaceable pins or bolts or the like. These signal carriers are frequently utilised only so that when the workpiece is processed defectively on a workpiece carrier, the same may be tagged as a scrap or waste workpiece. This is accomplished by the fact that the signal carriers are displaced from the so-called good position into the scrap or waste position by means of displacing means situated in the individual working or processing stations. Coding devices of this nature are occasionally also utilised for coding devised to perform different individual working operations on the workpieces of the workpiece carriers.These systems are not applicable in all cases however, since the displaceable parts require constant maintenance and the investment and space required for such devices is great, and since the further processing of the data obtained, especially by means of electronic control means, implies a substantial expenditure.

The present invention has as its fundamen tal object to devise a method and a device for characterising workpiece carriers for production plants and in particular for fully automatic production plants, where the coding element or signal carrier is situated on the workpiece carrier. Furthermore, it is an object in a simple manner to provide for discrimination between satisfactory and defective conditions of the individual workpieces, or of individual parts situated on the workpiece carriers, and to allow the coding element to be utilisable for the setting of the position of the individual workpiece or workpiece carrier.

In a method for coding workpiece carriers in production plants, in particular for assembling workpieces comprising several separate parts, according to the invention workpiece carriers are fed to successive work processing stations along conveyor tracks, at which stations the work operations on individual parts on the carriers are effected and wherein a defect signal is allocated to a workpiece carrier receiving such workpieces as had incurred defective assembling or processing, so that such workpieces are no longer processed in subsequent work processing stations or are fed to a delivery station for scrap parts or post-processing, in which after work operation has been performed on an individual part in a workprocessing station, the workpiece carrier has a coding member left in a switching position corresponding to a reject coding in the case of a defective work operation, or displaced into a switching position corresponding to an accept coding if the processing operations were performed in due form in the work processing station.

The problem of the invention is resolved in that a coding element of an individual part or work-piece carrier is allowed to remain in a switching position corresponding to reject coding in a working or processing station after an individual part has been supplied, fitted or processed therein, if a defective infeed, fitting or processing operation has occurred, or is displaced to a switching position indicating an accept coding if the processing operations had been duly performed in the working or processing station. The advantages of this unexpectedly uncomplicated solution consist in that in view of the allocation of coding elements in a switching position corresponding to reject coding, an accept coding may be secured only by a deliberate operational step and that a post-processing operation on scrap parts or their packaging and utilisation, are prevented with great reliability.

In accordance with a modified method, it is specified that the switching position of the coding element is detected prior to infeed, fitting or processing of an individual part in a subsequent working or processing station, and that if the switching position of the coding element corresponds to a reject coding, the individual parts or workpiece carriers are not processed in the working or processing station and that in the case of a switching position of the coding element corresponding to an accept coding, the said element is displaced in a mandatory manner in particular, into a switching position establishing a reject coding of the individual part of workpiece, from which it is displaced into a switching position establishing an accept coding if the processing and/or assembling operation is duly performed.

Thanks to the ''reject coding" of each individual part or workpiece carrier it may be assured that in case of a breakdown of the control system, only such individual parts or workpieces as have been properly assembled or processed are tagged as being defective.

For this reason, this method also offers a high degree of safety and is primarily appropriate for the production or processing of safety elements.

The invention includes a device which is also provided for characterising individual parts or workpiece carriers in a production plant comprising several working or processing or storing stations successively arranged in the conveying direction along a conveyor track, and a coding element allocated to the individual part or to the workpiece carrier, as well as detector or coder devices arranged along the conveyor track, which are coupled to a control device for this production plant for implementation of the method, by means of which it is possible to apply the method in accordance with the invention.

This device is characterised in that the individual part or workpiece carrier has allocated to it a displaceable coding member supported by the carrier which has switching positions indicating an accept coding or a reject coding, and which at a work processing station comprises a detector device, a switching element for displacing the coding member from the accept coding switching position into the reject coding switching position, and a coding device comprising a switching element for displacing the coding element from a reject coding switching position into an accept coding switching position.Thanks to the separation of the device into individual modular components, it is possible to establish a space-saving pattern in the area close to the workpiece carrier or to the conveyor track, and the device may simply be reset to different processing positions, in particular in the case of workpiece carriers comprising several reception means for individual parts.

According to another and very essential feature of the invention, it is specified that the coding element be formed by a signal pin installed in a holder and displaceable at right angles to the travel direction of the individual parts or workpiece carrier, which has securing means allocated to it in the two switching positions, whereby it is assured that no accidental spontaneous displacement of the signal pin is possible during the travel of the individual parts or workpiece carriers from one working or processing station to the next.

It is also possible furthermore for the holder for the signal pin to be secured on a support bar situated on a lateral edge of a workpiece carrier and comprising bores situated one behind the other at predetermined intervals, and for the signal pin to be aligned at right angles to the conveying plane of the conveyor track, and for the coding device, the scan or detector device and the switching element to be displaceably installed on a mounting bar which is equipped with several fastening bores arranged one behind another with mutual spacing and secured on the guiding bars of the conveyor track.Thanks to the incorporation of a support bar for the holder of the signal pin on the workpiece carrier, its position maybe adapted in an uncomplicated manner to different conditions, or in other words, each workpiece carrier may be equipped as standard with appropriate support bars and the holder for the signal pins and the like may then be installed at the position required in each case, in a versatile manner.

A form of embodiment is also advantageous in which the switching element post-connected to the scan or detector device is formed by a switching member comprising a switching slide or the like for the signal pin, and the switching element of the coding device is constructed as a displaceable pistoncylinder system, since the signal pin allocated to an individual part is displaced to the switching position corresponding to the reject coding by means of the switching slide, in a mandatory manner, prior to the processing of the individual part.

Furthermore, it is also possible however for the switching element and the coding device to have installed between them another detector device which corresponds to a working or processing point of the individual part situated on the workpiece carrier. The signal carrier may thereby advantageously be utilised at the same time as a positional emitter for an individual part situated on the workpiece carrier, so that the latter may be directed precisely in position at a working or processing station.

It is also advantageous however for the support bar of the workpiece carrier to have installed on it several successively positioned coding members in the direction of travel, which are in each case allocated to one of the workpieces arranged on the workpiece carrier.

Thanks to the small space requirement of the coding members according to the invention, it is possible to allocate the coding members with the closest possible correspondence to the workpieces, even if the latter are small.

It is finally also possible within the scope of the invention that the holder for the coding member may comprise several rows of signal carriers extending parallel to the direction of travel, which with respect to the surface of the signal carrier plate in particular are protruding and/or displaceable with respect to the frame as well as arranged spaced apart in the direction of travel, and for detector elements allocated to the separate rows of signal carriers to be situated in the scan or coding device. A plurality of different data regarding the workpiece carrier or the workpieces or individual parts arranged thereon may thereby be communicated to the detector elements in the separate working or processing stations, a precise monitoring operation in respect of the different working processes being possible thereby.

The invention will now be described, by way of example, with reference to the accompanying partly diagrammatic drawings, in which: Figure 1 is a perspective view from above of a machine table of a production plant and comprising a coding device according to the invention, for characterising individual parts or workpiece carriers, which is situated in the working area of a processing station for cooperation with the workpiece carriers, Figure 2 is an end view partly in section of the coding device illustrated diagrammatically in Figure 1, Figure 3 is an inverted fragmentary view of part of a signal carrier plate comprising several rows of signal carriers extending side-byside parallel to a direction of travel, and forming several scanning rows extending transversely to the direction of travel, in a diagrammatical form of illustration, generally viewed along the lines Ill-Ill in Figure 2, Figure 4 is a plan view of a working or processing station incorporating the components of a coding device in accordance with a further embodiment of the invention for characterising individual parts, Figure 5 is a partly sectional side elevation of the coding device taken along the lines V-V in Figure 4.

A machine table 1 of a work processing station 2 of a production plant is illustrated in Figure 1. The work processing station 2 comprises a conveyor track 3 for workpiece carriers 4 with individual parts 5 arranged on the carriers 4, which parts may form a workpiece 6. These individual parts 5 may be processed, supplied, fitted or worked in some other optional manner in the work processing station 2. The separate actions described in the foregoing may be performed manually or in a fully automatic or semi-automatic manner. The workpiece carriers 4 are associated with friction roller drives 7 to convey them along the conveyor track 3.A coding device for characterising individual parts 5 or workpiece carriers 4, which is denoted generally by the numeral 8, is incorporated for monitoring the displacement of the workpiece carriers or the implementation of the work processing operations on the individual parts 5. The coding device 8 for characterising the individual parts 5 or workpiece carriers 4 incorporates a coding element 9 mounted on the carriage 4, and a scan or detector device 10, a switching element 11 and a coding device 12 which are arranged partially recessed in a table plate 14 beside the guiding bar 13 of the conveyor track 3, below the path of travel of the coding element 9.

An embodiment of a coding element 9 is illustrated in Figure 2. This coding element 9 comprises several signal carriers 19 to 21 which are arranged as seen in Figure 3 side by-side in several rows 1 6,1 7 and 1 8 extending in the direction of travel on a signal carrier plate 15. The signal carriers 19 and 20 are fixedly installed on the signal carrier plate 15, whereas each signal carrier 21 in the row 18 is formed by a signal pin 22 which is vertically displaceable with respect to the signal carrier plate 15. Detector elements or sensor elements 23 forming parts of detector device 10 and by means of which it is possible to detect the position of the protruding signal carriers 19 and 20 or of the displaceable signal pin 22, areassociated with separate rows of the signal carriers 19 to 21.The different positions of each signal pin 22 is determined in the row 18 by means of the sensor element 23 by means of an electromagnetic field of the sensor element 23 which is constructed as an electromagnetic limit or proximity switch which is activated when the signal pin 22 is present in the lower dashdotted position 24, whereas the sensor element 23 is not activated in the position 25 shown by solid lines.

It is more clearly apparent from Figure 3 that several signal carriers 19, 20 and 21 in the rows 16 to 18 are associated into transverse scanning rows 26. The signal carriers arranged one behind another in rows 16 and 17 may serve the purpose of establishing a code number formed by a binary numeric combination for the workpiece carrier 4, whereas the signal carriers situated in the row 17 for example may be utilised for generating a continuous timing pulse. The signal carriers 21 may for example be allocated to two workpieces 6 arranged one behind another with mutual spacing on the workpiece carrier 4, for the purpose of characterising the momentary processing condition accept/reject of these and furthermore of positioning the workpieces 6 successively in the processing position.

A modified embodiment of a device in accordance with the invention, intended to characterise a workpiece carrier 4 or the workpiece 6 situated thereon, is illustrated in Figure 4. On one lateral edge 27 of the workpiece carrier 4 is secured a support bar 28 in which several bores 31 are formed at predetermined intervals 29 in the direction of travel - arrow 30-as shown in Figure 5. An assembling bar 33 which is equipped with fastening bores 34, equally at predetermined intervals, for example but not necessarily at the same intervals 29 as on the support bar 28, is situated on a lateral edge 32 of the guiding bar 13 facing away from the workpiece 6. A holder 35 in which is situated a displaceable signal pin 22, is secured in a bore 31 of the support bar 28. This signal pin 22 has a lower switching stud 36.As more clearly apparent from Figure 4, the signal pin 22 is aligned transversely of the conveying direction 30 on a central axisdash-dotted line--of the workpiece 6.

This signal pin 22 is associated with a first detector device 10 which comprises a sensor element 37. This sensor element 37 has allocated to it a switching element 38, e.g.

comprising a switching slide 39 which has an oblique position inclined forwardly and downwardly in the direction of travel with respect to the workpiece carrier 4. Another detector device 10 comprising a sensor element 37 is forwardly in the direction of travel 30 from the first device 10 and is associated with a predetermined processing station for the central axis of the workpiece 6.

The further detector device 10 is followed by a coding device 12 incorporating a switching element 40 formed by a piston-cylinder system comprising a switching member extendable in the direction of the workpiece carrier 4.

If the workpiece carrier 4 is then being moved along the conveyor track 3 in the direction of travel, the position of the signal pin 22 is detected after arrival in the working or processing station 2. If the said pin 22 is then situated in the lower switching position 24 shown by solid lines in Figure 5 and corresponding to a reject coding, the workpiece carrier 4 travels through the working or processing station 2, preferably without stopping at the same.If, on the contrary, the switching pin 22 situated at the upper switching position, meaning the accept coding position, is moved past the detector device 37, e.g. being an electromagnetic limit or proximity switch or a reflected light sensor, a Hall generator or the like, this does not cause any signal state alteration at the output side of the detector element 37 and the detector device 10 allocated to the processing position is activated. At the same time, upon advancing the workpiece carrier 4 in the conveying direction, the sloping switching slide 39 causes the signal pin 22 to be lowered on to the switching stud 36 into the switching position indicating a reject coding from the switching position indicating an accept coding.The switching stud 36 is thereby moved within the range of action of the sensor element 37 and the workpiece carrier may be arrested and positioned upon reaching the second detector device 10, to perform a working or processing operation.

After completion of the processing operation, the workpiece carrier 4 continues to move in the direction of a coding device 12.

If the preceding working or processing operation had been performed properly, the piston-cylinder drive forming the switching element 40 is extended when the switching pin 22 is being moved past this coding device 12, and the signal pin 22 is displaced upwards into the upper switching position-into the accept coding position shown by solid lines in Figure 2.

If, by contrast, the working or processing operation had not been implemented in due form, the coding device 12 is not activated and the workpiece carrier 4 moves past the coding device 12 without the switching pin 22 being displaced in the holder 35. The workpiece carrier 4 is thereby detected as being a waste scrap component in the working or processing station, and no longer processed or fed to a post-processing station.

The retention of the signal pin 22 in the switching positions 24,25 is suitably performed by means of securing devices 41 formed by spherical thrust members, for which purpose the signal pins have grooves machined in them at the two extreme positions, with balls spring-loaded within the holder engaging in the said grooves at the momentary switching positions.

Claims (12)

1. A method for coding workpiece carriers in production plants in particular for assembling workpieces comprising several separate parts, in which workpiece carriers are fed to successive work processing stations along conveyor tracks, at which stations work operations on individual parts on the carriers are effected wherein a defect signal is allocated to a workpiece carrier receiving such workpieces as had incurred defective assembling or processing, so that such workpieces are no longer processed in subsequent work processing stations or are fed to a delivery station for scrap parts or post-processing. in which after work operation has been performed on an individual part in a work processing station, the workpiece carrier has a coding member left in a switching position corresponding to a reject coding in the case of a defective work operation, or displaced into a switching position corresponding to an accept coding if the processing operations were performed in due form in the work processing station.

2. A method according to claim 1, characterised in that before an individual part on the carrier is subject to a work operation in a following work processing station,the switching position of the coding member is determined and the individual parts on the workpiece carriers are not processed in the said following work processing station if the coding member is in the switching position corresponding to a reject coding, and that if the coding member is in a switching position corresponding to an accept coding, the said coding member is mandatorily displaced in particular into a switching position defining a reject coding from which it is displaced into a switching position defining an accept coding if the work operations had been performed satisfactorily in said following work processing station.

3. A device for coding individual parts on workpiece carriers in a production plant, comprising several work processing stations arranged in succession in a conveying direction along a conveyor track, and a coding member allocated to the individual part on the workpiece carrier, as well as detector or coder devices situated along the conveyor track, which are coupled to a control device for the production plant, for implementation of the method according to claim 1, in which the individual part on the work-piece carrier has allocated to it a displaceable coding member supported by the carrier and which has switching positions indicating an accept coding or a reject coding, and which a work processing station comprises a detector device, a switching element for displacing the coding member from the accept coding switching position into the reject coding switching position, and a coding device comprising a switching element for displacing the coding member from a reject coding switching position into an accept coding switching position.

4. A device according to claim 3, in which the coding member is formed by a signal pin which is installed in a holder and is displaceable at right angles to the direction of travel of the carrier and which has means for releasably retaining it in each of the switching positions.

5. A device according to claim 4, in which the holder for the signal pin is secured on a support bar arranged on a lateral edge of a workpiece carrier and comprising bores formed at successively predetermined intervals in the direction of travel and the signal pin is aligned at right angles to a conveying plane of the conveyor track, and in which the coding device, the detector device and the switching element are arranged adjustably on an assembling bar which is equipped with several fastening bores for the devices arranged successively at predetermined intervals in the direction of travel and is secured on a guiding bar of the conveyor track.

6. A device according to claim 3, in which a switching element post-connected to the detector device comprises a switching slide for the signal pin, and a switching element of the coding device is constructed as a displaceable piston-cylinder device.

7. A device according to claim 6, in which between the switching element and the coding device is disposed a further detector device at a position corresponding to a work processing station for an individual part situated on the workpiece carrier.

8. A device according to claim 7, in which several successively arranged further coding members are disposed at intervals in the direction of travel on the support bar of the workpiece carrier and which correspond to respective work processing stations for workpieces arranged on the workpiece carrier.

9. A device according to claim 5, in which the holder for the coding member has several rows of signal carriers extending parallel to the direction of travel and which protrude from a surface thereof, the signal carriers in the rows being spaced in the direction of travel, and the detector and coding devices comprise sensor elements associated with respective rows of signal carriers.

10. A device as claimed in claim 9, in which signal carriers of the rows extending in the direction of travel are arranged in rows extending transversely thereof.

11. A method as claimed in claim 1 and substantially as described with reference to the drawings.

12. A device as claimed in claim 3 and substantially as described with reference to Figures 1 to 3 or 4 and 5 of the drawings.