EP0303084A2 - Method and device for measuring objects on a conveyor section - Google Patents

Abstract

The invention relates to a method and a device for detecting the position, shape or the like of objects which are moved by means of a conveying path, an object being separated from the conveying path in the region of the measuring point, and proposes, for the purpose of achieving a reliable recognition and optimum detection in terms of measuring technology for the separation of the objects, that the object (10) is led on the conveying path (3) along the measuring point, in that, superimposed on the forward movement of the object on the conveying path, a lifting off of the object from the conveying path occurs in the region of the measuring point, in that a detection, by means of measuring technology, of one dimension of the object is carried out in the lifted-off state and that the measured value detected in the lifted-off state is compared with a reference value. <IMAGE>

Description

The invention relates to a method according to the features of preamble 1 and a device according to the features of the preamble of claim 6.

Various devices are known for conveying objects, in particular conveying objects to processing machines, such as, in particular, so-called vibratory conveyors. In this regard, reference is made, for example, to German patent application P 3331050.5-14. On the technology of the vibratory feeder in general also on the essay "It is enough for a whole shift" by Peter S. Niess and Norbert Schmitz in OPERATING TECHNOLOGY 10/82, page 61-64.

Such conveyors very often should not only solve the task of feeding objects to downstream processing or processing devices, but in practice it is often required that sorting, specific alignment of the objects, sorting out of incorrectly processed objects etc. is carried out becomes. For this purpose, it is known, for example (cf. DE-Gm 85 34 584), to scan the objects by means of a light barrier beam and to remove objects that are not recognized or recognized as incorrect from the conveyor path by means of a pulsor arranged in the barrier plane. However, with this known device, it is necessary to enter the conveying path of the vibrator conveyor to install an intermediate piece, which does not resonate, since the objects are only supposed to slide through the measuring point, but not vibrate when performing micro-throws. In addition, the known measuring methods cannot be used to determine whether the objects that pass the measuring point also meet the requirements with regard to the design of the surface with which they rest on the conveyor track.

In view of this state of the art, the object of the invention is to further develop and design the known method and the known device in such a way that, with the simplest possible construction of the measuring point with regard to the conveyor track, reliable detection of objects to be separated out is possible, with the most comprehensive metrological detectability of the Objects.

The object is achieved by the inventions specified in claims 1 and 6.

In a method according to the invention, it is not necessary, for example when used in an oscillating conveyor, to provide a non-oscillating section of the conveyor track in the area of the measuring point. Rather, it is even necessary that there is also an oscillation in the area of the measuring point, which moves the objects by means of micro-throws, thus causing the objects to be lifted off the conveyor track. In addition, the lifting of the objects required to carry out the invention can also be achieved in other ways.

The fact that the invention is realized in the case of objects which stand out from the conveyor track in the area of the measuring point does not mean that only devices are designed according to the invention in which the objects are lifted off the conveyor track in the area of the measuring point without exception. Depending on the design of the device, in practice some of the objects also move past the measuring point without being lifted, for which, as will be explained in more detail below, a slot or a transparent part is provided in the region of the measuring point in the conveyor track. Characterized in that - in the raised state or by the slotted design of the conveyor track - a measurement is carried out on the height of the object, the underside of the object is also detected, for example the thickness of the object. Any breakthroughs in the object can also be detected. The comparison with stored measured values determines whether the object detected by measurement is "good" or whether it should be discarded.

In an embodiment of the method it is provided that a series of measurements are subsequently carried out while an object is moving past the measuring device, so that the length of an object can also be determined by a measuring device which records the measured values over the height of the object. However, since the objects move past the measuring point only with special measures, especially in the case of vibration conveyance, in parallel, or in another, but defined manner, a value can easily be detected with regard to the length dimensions, which apparently does not match the predetermined target value , for example, if an object moves obliquely at the measuring point and only the projection of its length is measured as length. Here, the invention therefore further proposes that measured (partial) dimensions are in each case related to a given dimension in the case of an object which has different areas, and relative values thus obtained are compared with stored relative values. If an object has approximately a total length of 6 mm, which can be divided into a first section of 3 mm with a thickness of 2 mm and a second section, likewise with a length of 3 mm, but with a thickness of 4 mm, it can can be measured that the first length range represents 50% of the total length and the second length range also. Parts in which the measured partial dimensions do not each represent 50% of the total length must therefore be discarded in this case. The formation of relative values can also be carried out in such a way that the measured partial dimensions are related to the measured overall dimensions. However, as indicated, predetermined stored dimensions can also be used to form the relative values. It is essential that the measured values are not used directly for comparison. At least with regard to length measurements. Thickness measurements can also be used immediately.

It is further preferred that the measurement is carried out at high frequency, for example a frequency which is between 1 and 20 MHz can be given. A very dense grid of measured values can thus be obtained.

Depending on the result of the comparison of the measured values, the object can then be separated from the conveyor track. For example, by means of a pneumatic pulsor, a trap, a plunger or the like already mentioned. The separation is also possible by means of a magnet, for example designed as an electric lifting magnet.

In terms of the device, the invention proposes that the conveyor track in the area of the measuring point is a partial area of an oscillating conveyor track, that the measuring point is realized by opto-electronic elements and that a comparison of measured values with stored measured values can be carried out. However, the invention is not limited to the fact that the conveyor track is designed as part of an oscillating conveyor track in the area of the measuring point. Another type of lifting can also be implemented, for example on a pneumatic basis.

It is particularly preferred that the measuring point itself is formed by a so-called CCD line. CCD lines are known, for example, from camera technology. In particular, several such lines can also be arranged next to one another, in the form of a so-called "array". Such a light sensor line can have a size of about 3 mm (256 optoelectronic elements <bixel>) up to 27 mm (2,048 bixel).

A further preferred embodiment is based on the fact that such CCD lines are arranged in two dimensions, that is to say, for example, for detecting the height of a transported object and transversely to the conveyor track for detecting the width of a transported object.

Since the conveyor track in the area of the measuring point, for example in the case of a vibratory conveyor, is a normal section of a conveyor track of such a vibratory conveyor, it can occur, depending on the width of the conveyor track, that two objects lie side by side or partially, due to the relatively disordered movement of the objects on a vibratory conveyor moving past the measuring point. The objects can also lie so closely one behind the other that misinterpretations of the length can occur in the optoelectronic system. In order to remedy this, the invention further proposes that the conveyed objects can be separated on the conveyor track in the conveying direction in front of the measuring point. Various measures are suitable for this. For example, the objects could be braked pneumatically. A mechanical barrier is also conceivable. On the other hand, the system helps itself, as it were, with objects lying side by side or immediately one behind the other, since these are understood to be an object which has impermissible dimensions and are therefore rejected by the system. Depending on the application, this can lead to an undesirable delay, so that it is advantageous to carry out the aforementioned separation.

It is preferred within the scope of the invention that the conveyor track in front of the measuring point has a hump or the like rising above the level of the conveyor track in the area of the measuring point. On the rising side of this hump, the conveyance results in a jam of the objects, while an object that has overcome the apex of the hump experiences acceleration on the falling side and thus moves individually past the measuring point.

It is advantageous that the conveyor line is interrupted in the area of the measuring point in order to reliably ensure continuous detection of an object moving past its height. To this end, the invention proposes that the conveying path in the area of the measuring point be made translucent. In particular, it can be simply slotted or can be transparent. The fact that the slot or the transparent formation is located in the side boundary of the conveyor track in the area of the measuring point, but also in the conveyor track itself, means that objects which are not lifted and which, for example, only slip through the measuring point, can be completely grasped.

It is also essential that the measuring device is firmly connected to the vibrating part of the conveyor. The measuring device vibrates with the conveyor. There is no relative movement between the measuring device and the conveyor track. As a result, the slot or the transparent design of the conveyor track in the region of the measuring point can advantageously be kept small, so that even very small objects can be measured using the described device.

Finally, in terms of the device, an element is also provided, with which an object is acted on can, after it has passed through the measuring point, be it to separate it, ie to remove it from the conveyor track or to align it in the desired manner. A pneumatic pulsor is suitable for the separation. In addition, such facilities as have already been mentioned above.

• Fig. 1 eine Prinzipskizze eines Vibrationswendelförde­rers, mit schematisch angedeuteter Meßeinrichtung gemäß der Erfindung;
• Fig. 2 eine Prinzipdarstellung eines Vibrationslinearför­derers;
• Fig. 3 eine vergrößerte Ansicht einer Förderbahn eines Vibrationslinearförderers, mit erfindungsgemäßer Meßeinrichtung;
• Fig. 4 eine vergrößerte Detaildarstellung der Vorbeibewe­gung eines Gegenstandes an der Meßeinrichtung;
• Fig. 5 eine Einzeldarstellung eines zu messenden Gegen­standes (5 a) sowie die schematische Darstellung möglicher Meßprotokolle (5 b, 5 c).

The invention is explained in more detail below, but only by way of example, with reference to the accompanying drawing, in which:

• Figure 1 is a schematic diagram of a vibratory bowl feeder, with a schematically indicated measuring device according to the invention.
• 2 shows a schematic diagram of a linear vibratory conveyor;
• 3 shows an enlarged view of a conveyor path of a linear vibratory conveyor with a measuring device according to the invention;
• 4 shows an enlarged detailed representation of the movement of an object past the measuring device;
• Fig. 5 is an individual representation of an object to be measured (5 a) and the schematic representation of possible measurement protocols (5 b, 5 c).

Shown and described first of all in FIG. 1 is a vibratory spiral conveyor 1, which has a measuring device 2, with which objects can be detected by measuring technology, without special "calmed" sections in the conveyor track 3 being required.

The basic structure of a vibratory bowl feeder according to FIG. 1 consists of a basic unit 4, leaf springs 5, which connect the base unit 4 to the parts container 6 and a vibration exciter 7.

A linear vibratory conveyor according to FIG. 2 is constructed in a comparable manner in principle.

The device according to the invention, which is shown in detail in FIG. 3, consists of a CCD line 14 (which in the exemplary embodiment is arranged in the element provided with the reference number 14, but is not shown in detail), which is opposite one of the conveyor track 3 arranged light source 8 is illuminated. The conveyor track 3 is interrupted in the area of the measuring point, in the form of a slot 9, in order to ensure a reliable measurement of the objects 10 moving past the measuring point.

In the conveying direction in front of the measuring point, the conveyor track 3 has a hump 11 on which the objects 10 move upwards as a result of the vibration movement, whereby they come into close contact with one another. As soon as the objects 10 have overcome the apex 12 of the hump 11, they experience an additional acceleration and occasionally move past the measuring point or the CCD line 14.

In the conveying direction behind the measuring point, for example, a pneumatic pulsor 13 can be provided for the rejection.

In the embodiment of Figure 3, for example, the object 10 ', which has already passed the measuring point, is misaligned, namely its pin-like approach of smaller diameter is on the front, while it should be on the back according to the desired order, the object So it should move around 180 ° on the conveyor track 3. Therefore, in the exemplary embodiment, this object 10 'is removed from the conveyor track 3 by means of the pulsor 13. The same goes with the object in front of the measuring point 10˝ happen when this passes the measuring point.

As can be seen in particular from FIGS. 1 and 2, the measuring device 2 is firmly connected to the vibrating part of the vibratory spiral conveyor 1. The measuring device 2 carries out the vibrations of the vibratory spiral conveyor 1. In this way, an optimally small slot 9 can be realized, which accordingly enables very small objects to be conveyed and measured using such a system. In Fig. 3, the rear wall 16 of the vibratory bowl feeder is not shown for clarity, while it is also shown in Fig. 4. The slitting of the rear wall 16 in the area of the measuring point can also be seen. Only for better illustration is the measuring point 14 and the pulsor 13 drawn at a relatively large distance from one another in FIG. 4. In fact, however, these elements are arranged very close to one another in order to be able to carry out the necessary sorting out immediately after the measurement.

In Fig. 4, the moving past of an object 10 at the measuring point 14 is shown schematically in an enlarged view. The object 10, which is indicated in dashed lines 10 ‴ in the raised state, follows approximately a zigzag-shaped movement path 15 on the conveyor path 3. The object 10 is raised by the vibration promotion, in the position according to 10 ‴, and at the same time moved forward. FIG. 4, however, shows the movement of an object 10 only schematically. In practice, many more movement possibilities occur. The object can tumble, slant, etc. past the measuring point. The metrological detection takes place in the position in which the relevant section of the object is currently moving past the measuring point 10. Therefore, once the measured values are recorded on a log paper running at a constant speed, measurement protocols (idealized representation) result according to FIG. 5.

5 a shows an object 10 to be measured, the first section of which has a length L 1 and a diameter D 1 and the second section of which has a length L 2 and a diameter D 2. 5 b shows a measurement in which the object 10 has moved very slowly past the measuring point. A corresponding number of measurements have been carried out. The lengths L 1 and L 2 therefore appear larger than they actually are for the object to be measured. For this reason, relative values are formed with regard to the lengths, either with predetermined constant values or based on the measured total length and, as already described above, only the relative lengths of the sections to be recorded are compared with one another. The thicknesses D 1 and D 2 correspond almost to the actual values in this example. Moving the individual sections past the measuring point at different heights results in the height offset in the measurement log and, with respect to the length L 2, the increasing profile. In the measurement protocol according to FIG. 5 c, the object has moved past the measurement point relatively quickly. Correspondingly, smaller lengths than actually exist appear on the measurement protocol. This can be remedied by the relative value formation described.

The features of the invention disclosed in the above description, the drawing and the claims can be of importance both individually and in any combination for realizing the invention in its most varied form.

Claims (18)

1. A method for detecting the position, shape or the like of objects (10) which are moved by means of a conveyor track, an object being separated from the conveyor track (3) in the area of the measuring point, characterized in that the item is on the conveyor track is guided along the measuring point, superimposed on the forward movement of the object on the conveyor track in the area of the measuring point, the object is lifted off the conveyor track, that a measurement of a dimension of the object is carried out in the lifted state and that the measured value recorded in the lifted state is accompanied by a Target value is compared. 2. The method according to claim 1, characterized in that the lifting of the object is carried out by an oscillation of the conveyor track. 3. The method according to claim 1 or 2, wherein an object is measured in sections, characterized in that in the case of an object which has different areas, measured (partial) dimensions are in each case related to a predetermined dimension and relative values obtained in this way are used for comparison . 4. The method according to any one of claims 1 to 3, characterized in that the measurement is carried out at high frequency, for example with a frequency between 1 and 20 MHz. 5. The method according to any one of claims 1 to 4, characterized in that an action on an object can be triggered depending on the measured value comparison. 6. Device for detecting the length, shape or the like of objects on a conveyor track, in particular for performing a method according to any one of claims 1 to 5, characterized in that the conveyor track (3) in the area of a measuring point is a partial area of an oscillating conveyor track, that the measuring point is realized by opto-electronic elements (7) and that a comparison of measured values with stored measured values can be carried out. 7. The device, in particular according to one or more of the preceding claims, characterized in that the measuring point is formed by a so-called CCD line (7) which can be illuminated by a light source (8) arranged opposite the conveyor track (3). 8. The device, in particular according to one or more of the preceding claims, characterized in that a plurality of CCD lines (7) are provided. 9. The device, in particular according to one or more of the preceding claims, characterized in that one or more CCD lines (7) are arranged in two dimensions. 10. The device, in particular according to one or more of the preceding claims, characterized in that the conveyed objects (10) can be separated on the conveyor track (9) in the conveying direction in front of the measuring point. 11. The device, in particular according to one or more of the preceding claims, characterized in that the conveyor track (3) in front of the measuring point has a raised (11) or the like above the level of the conveyor track (3) in the area of the measuring point. 12. The device, in particular according to one or more of the preceding claims, characterized in that the conveyor track (3) is designed to be translucent in the region of the measuring point. 13. The device, in particular according to one or more of the preceding claims, characterized in that the conveyor track (3) is slotted in the region of the measuring point. 14. The device, in particular according to one or more of the preceding claims, characterized in that the conveyor track (3) is transparent in the region of the measuring point. 15. The device, in particular according to one or more of the preceding claims, characterized in that, depending on the measurement result, an action on the objects (10) can be carried out. 16. The device, in particular according to one or more of the preceding claims, characterized in that the objects (10) can be pneumatically acted on. 17. The device, in particular according to one or more of the preceding claims, characterized in that the objects (10) can be magnetically acted on. 18. The device, in particular according to one or more of the preceding claims, characterized in that the measuring device (2) with the vibrating part of the device (1) is fixedly connected.

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