The present invention relates to a device for position monitoring for a workpiece during travel, and to a method for position monitoring for a workpiece passing by, wherein the workpieces preferably consist, at least in part, of wood, wood materials, plastics material, or the like.
In the prior art, transport devices for transporting workpieces are known, in which workpieces travel past processing devices, such that the workpieces can be processed by the stationary processing devices during travel. In particular, rolling and sliding chains are used here, wherein the workpiece is conveyed in a manner clamped between the chain and a belt.
A central aspect of the transport devices known in the prior art consists in the position monitoring of the workpieces. Processing work in a transport device requires a high degree of accuracy of the workpiece position. In the prior art, position monitoring by means of scanning elements is known, wherein the workpieces actuate a movable component when passing by said component, as a result of which the position of a workpiece in the conveying direction of the transport device is ascertained.
However, mechanical scanning elements have several disadvantages: Inter alia, the flexibility of the transport device relative to changing workpiece geometries is low, the costs for maintenance, upkeep and cleaning of scanning elements of this kind are high, and surfaces, in particular highly sensitive surfaces, may be damaged on account of the mechanical contact of the workpiece.
Typically, the position in the feed direction is calculated using a rotary encoder and a position switch. However, in particular in the case of cost-effective chains, the problem arises that the chain links lengthen over the course of the lifecycle and under loading, as a result of which, when calculating the position, position deviations of several millimeters arise between the calculated position and the actual position on account of the values from the rotary encoder and position switch, such that a further scanning element or a sensor is required, which detects the actual position, in order to perform the processing to the required degree of accuracy.
Against the background of the known transport devices, an object of the transport device of the present invention is that of providing a cost-effective system by means of which it is possible to precisely determine the position of an individual chain link in the transport device along the conveying direction.
In particular, an object of the present invention is that of determining the position of a workpiece by means of precise detection of individual transport means, such as individual chain links of a transport device.
This object is achieved by a transport device according to claim 1 and by a method for determining a position of a transport device according to claims 11 and 16, as well as by a processing method for a workpiece in a transport device according to claim 23. Advantageous developments of these aspects of the invention can be found in the respective dependent claims.
Advantages of the present invention are increased flexibility, lower costs, lower servicing and repair outlay, higher processing quality, as well as prevention of damage to highly sensitive surfaces. Furthermore, the present invention makes it possible to calculate a very precise position of the workpiece, while cost-effective chains are used. Thus, automatic control of the feed can take place, depending on the state of the chain. Furthermore, for example the throughput rate of the processed workpieces can be increased, since no reduction of the feed rate is necessary in order to reach the required tolerances due to the improved positioning accuracy, in particular in the case of dynamic stress and loading states.
Further advantages of the present invention are the possibility for state monitoring of the transport device, and the maintenance and upkeep based on this. Servicing measures are also possible.
Overall, the present invention makes it possible to allow for a quicker feed rate at the same quality, which can lead to more efficient utilization of the machines.
(1) A transport device according to the invention for transporting workpieces according to a first aspect of the invention, which preferably consist, at least in part, of wood, wood materials, plastics material, or the like, comprises at least one transport apparatus which is configured such that it can move along a first direction, wherein the transport device comprises a marking which comprises a pattern along the first direction.
Making the marking on the transport apparatus firstly makes it possible to identify a transport means, for example with respect to a non-marked transport means, and secondly the marking on one transport apparatus makes it possible for the transport apparatus to be divided, along a first direction, into a region of the transport device which is located in front of the marking in the first direction, into a region which is located at the level of the marking in the first direction, and a region which is located behind the marking in the first direction.
The pattern of the marking makes it possible to subdivide the marking in the first direction, and thus to finely divide the above-described region at the level of the marking.
An advantage of said patterned marking is that it is possible to very precisely detect the position of the relevant transport apparatus during travel in the first direction, which may require knowledge of the position of the marking on the transport unit, and knowledge of the pattern on the marking.
A marking of this kind can be used not only for position determination along the marking, but also, in a manner similar to a barcode, for clear identification of one marking with respect to another marking. An identification of this kind can take place both manually and automatically, during travel. An automatic identification allows for the transport device to be incorporated in an Internet of Things environment. As a result, higher productivity, in particular in networked production environments, can be achieved.
(2) The transport device can preferably receive and transport a workpiece.
(3) The marking of the transport device is preferably an optical marking, a metal marking, an inductive marking, or a magnetic marking.
An advantage of an optical marking of this kind, compared with a conceivable non-optical marking, for example a magnetic marking or a marking by way of application of scanning elements, is that the optical marking can be detected by an optical sensor, such as a camera or a laser transceiver apparatus.
A metal, inductive or magnetic marking in turn has the advantage that no optical elements such as lenses or beam paths are required for reading the marking, as a result of which the position determination can also take place in contaminated environments. Non-optical markings are expedient in particular in the field of wood and plastics processing, since wood and plastics chips have a usually negligible influence on inductive or magnetic properties, and therefore, in particular compared with an optical marking, operation is possible when the space between the sensor and marking is contaminated.
(4) The pattern of the transport device can preferably be an incremental pattern, particularly preferably an incremental scale.
Within the meaning of this invention, an incremental pattern refers to a pattern which is configured in a first direction such that it comprises a sequence of alternating regions, for example black and white, wherein it is obvious that any color combination which offers a sufficient contrast between the two colors is possible, and the differentiation into black and white regions is selected merely in the interest of a simpler description.
It is noted that it is also possible for more than two colors to be provided, for example black, white and red. In particular, the possibility is mentioned of specifying an individual color for every region along the first direction of the marking, such that it is possible to identify the position along the first direction on account of the color of the region alone.
It is furthermore noted that, although in this case the incremental patterning is described as a color sequence, in the interest of simpler readability, the invention is in no way limited to optical markings. It is thus possible, for example, for “white” to correspond to the magnetic coding “0”, and “black” to correspond to the magnetic coding “1”. Similar applies for patterns comprising more than two colors.
Conceivable alternatives to this preferred embodiment are embodiments in which the pattern is non-incremental, such as a region that is patterned by means of letters printed thereon.
For example, the incremental pattern may be a pattern in which black and white regions alternate along a first direction, such that a black region follows after a white region, a further white region follows after the black region, and a further black region follows after the further white region, and so on. A pattern thus results which is similar to a barcode. The number of white and black regions is not particularly limited, but it is obvious that finer position determination is possible as the number of increments increases.
In principle, the length of the increments along the first direction, and in particular the black and white regions, is not limited, such that it is possible for there to be white regions which are longer, in the first direction, than other white regions, and black regions which are longer, in the first direction, than other black regions. This is advantageous in that, with knowledge of the sequence of the increments and in particular the different lengths of the regions, a determination of the position of the transport apparatus can take place based on a detail of the incremental pattern.
In the event of all the regions of the same color being of the same length along the first direction, reference is made, within the meaning of this application, to an incremental scale. An incremental scale is advantageous in that, with knowledge of the position of the marking on the transport element during travel by counting the regions of the same color (for example black) travelling past a, for example stationary, sensor, and with knowledge of the length of black and white regions, a highly accurate position determination of individual transport apparatus during travel is possible.
(5) The marking of the transport device is preferably arranged on a lateral surface of the transport device.
Conceivable alternatives are application of the marking to the upper face and to the lower face of the transport device.
Compared with application to the upper side, this preferred embodiment is advantageous in that workpieces to be transported are routinely transported on the upper face or on the lower face of a transport device, and thus covering of the marking by the workpiece is prevented.
Furthermore, this preferred application to the side offers simple assembly as well as the possibility of cleaning during travel without interrupting the operation, for example by a laterally applied stationary brush.
(6) The transport device preferably comprises at least one transport apparatus which does not comprise any marking.
In the case of transport devices in which a plurality of transport apparatus is provided, having a known sequence and mutual spacing, this embodiment makes it possible to provide just a subset of the transport apparatus with patterns and nonetheless to sufficiently precisely monitor the position of the transport means, as a result of which costs can be saved compared with an alternative in which a marking is applied to every transport unit.
(7) A transport device preferably comprises a plurality of transport means, wherein the transport apparatuses are interconnected, and are in particular annularly interconnected.
This embodiment is advantageous compared with an embodiment in which a plurality of transport apparatus is provided which are not interconnected, in that firstly the connection of the transport units specifies the mutual spacing of the transport units, and secondly an annular connection makes possible a continuous processing process, similar to a conveyor belt.
(8+9+10) According to the first aspect of the present invention, a transport device preferably comprises a sensor device for reading out the marking, wherein the transport apparatus is in particular configured such that it moves along the first direction relative to the sensor device.
Compared with a possible alternative in which the transport device is not configured having a sensor device, for example a transport device in which the read-out of the marking is performed by eye, this preferred embodiment makes it possible to detect the position of the transport unit automatically and by machine, which increases the processing speed. A transport device, which moves relative to the sensor device, allows for fixed or stationary positioning of the sensor device.
(11) A method according to the invention for determining a position of a transport apparatus along a first direction comprises reading out a region of the marking of a transport device according to the invention, processing an item of information which is obtained from the reading out, comparing a processed item of information with stored information, a determination step in which a change of a current position with respect to a previous position is determined on the basis of the comparison, and a storage step.
This method is advantageous in that, on the basis of the comparison of an item of processed information, obtained from the read-out, for example a counting step of an increment of an incremental scale, and the knowledge of the length along the first direction of an increment, and the knowledge of a position of the transport apparatus before the counting step, a current position of the transport apparatus can be determined precisely.
In the event of the pattern not being an incremental scale, the information from the read-out can for example be an item of information relating to a portion of the pattern, and the stored information can be information relating to the overall structure (and the sequence of the portions) of the pattern. In this case, the determination step contains a step in which the information read out is compared with the stored information, as a result of which precise position determination on the pattern is also possible.
(12) The stored information of the method preferably comprises an item of information relating to the pattern of the marking.
Compared with a step in which the stored information does not include any information relating to the pattern of the marking, for example in a case in which the stored information contains exclusively an item of information relating to a chronologically preceding item of information, the advantage of an item of stored information relating to the pattern of the marking is that the position of the transport unit can be determined exclusively on the basis of a detected portion of the marking.
(13) The storage step preferably comprises storing the processed information. Compared with a storage step which does not involve any storage of the processed information, such as a storage step exclusively comprising a timestamp, a method in which the storage step comprises storing of the processed information makes it possible to determine, in a following processing step, the path travelled since the last step.
(14) The stored information of the method preferably comprises an item of information relating to the position of a transport apparatus prior to reading out the marking of the transport means.
Compared with an alternative embodiment in which the stored information of the method does not comprise any information relating to the position of a transport apparatus prior to reading out the marking of the transport means, for example only an item of information relating to the pattern, this embodiment is advantageous in that it is possible to determine the movement of a transport device between two readout time points.
(15) In the method, a current position, with respect to a fixed reference point, is preferably determined on the basis of the comparison of the change in a current position.
Compared with a method in which no change of the current position is determined, but merely one position, this embodiment allows for a determination of the movement of the transport means.
(16) According to the invention, a method for determining the position of a workpiece in a transport device comprises a step of determining a spacing between a reference point of a marking of a transport apparatus and a reference point of a workpiece.
This method is advantageous in that the position of the workpiece can be determined based on the determination of a position of a marking on a transport means, which allows for precise machining or processing of the workpiece.
(17) In the method for determining the position of the workpiece, the spacing in the first direction is preferably measured.
Compared with a method in which the spacing in another direction is measured, this embodiment is advantageous in that the position of the regions which terminate the workpiece to the front and to the back, in the first direction, can be precisely determined, which is advantageous in particular if these regions are to be processed.
(18) In the method for determining the position of the workpiece, the reference point of the marking is preferably positioned at a front end of the marking, in the first direction.
Compared with an embodiment in which the reference point is not positioned at the front end of the marking, in the first direction, but rather is positioned for example in the center of the marking, this embodiment is advantageous in that the position determination can take place while the marking is moving.
(19) In the method for determining the position of the workpiece, the reference point of the workpiece is preferably positioned at a front end of the workpiece, in the first direction.
Compared with an alternative in which the reference point of the workpiece is not positioned at a front end in the first direction, this embodiment is advantageous in that, in the case of a workpiece of which the front end is to be processed, the processing of the determined data is less complex, and thus less error propagation occurs when calculating the position of the region to be processed.
(20) The method for determining the position of the workpiece preferably comprises a step of determining the position of the reference point of the workpiece with respect to a reference point of the transport device.
Compared with a method that does not comprise this step, for example in which the workpiece is arranged on the transport device without the relative position of the transport device and workpiece being determined, this embodiment is advantageous in that it is possible to precisely determine the position of the regions of the workpiece to be processed during travel.
(21) In the method for determining the position of a workpiece, the transport device is preferably a transport device for transporting workpieces which preferably consist, at least in part, of wood, wood materials, plastics material, or the like, and comprises at least one transport apparatus which is configured such that it can move along a first direction, wherein the transport device comprises a marking which comprises a pattern along the first direction.
Compared with an alternative in which the method comprises the position determination without a marking having a pattern in the first direction, this embodiment is advantageous in that the determination of the position of the transport element can be carried out on the basis of the marking and the pattern, allowing for highly accurate position determination.
(22) In the method for determining the position of the workpiece, the determination of the position of the reference point of the marking preferably comprises a method for determining a position of a transport apparatus along a first direction, comprising the following steps:
reading out a region of the marking of a transport device,
processing an item of information which is obtained from the reading out,
comparing a processed item of information with stored information,
a determination step in which a change of a current position with respect to a previous position is determined on the basis of the comparison, and
a storage step.
This embodiment makes it possible to precisely determine the position of the workpiece during travel.
(23) In a processing method according to the invention for a workpiece in a transport device, the workpiece is processed on a transport device using a tool.
This method makes it possible to process the workpiece during travel.
(24) The workpiece is preferably moved, on the transport means, relative to the tool.
Compared with an alternative in which the workpiece is not moved relative to the tool, this embodiment makes it possible to establish assembly line-like operation.
(25) A relative position of the workpiece with respect to the tool is preferably determined by means of a method for determining the position of a workpiece in a transport device.
This method makes it possible to precisely determine the position of the workpiece during travel and to carry out the processing of the workpiece on the basis of the position determination, leading to a more precise processing result.
(26) According to the invention, in a method for identifying a transport means, the transport apparatus is identified by reading out the marking, wherein at least one of the markings differs from at least one other marking.
A method of this kind makes it possible for individual transport elements to be identified, with respect to other transport elements, in a processing environment.
(27) According to the invention, in a method for controlling a transport device, control of a feed rate is carried out on the basis of an item of information which is obtained from a read-out of at least one of the markings.
An item of information from a marking of this kind may for example be an item of information relating to a workpiece transported on the marked transport means. In the case of workpieces requiring a lower processing quality, a faster feed rate can be set on the basis of this information, whereas in the case of transport apparatus which transport workpieces requiring a higher processing quality, a lower feed rate can be set. More efficient utilization of the transport device can thus be made possible.
Alternatively thereto, it is possible for an item of information relating to a state of the chain, for example relating to a chain length, to be obtained from reading out one or more markings. The feed rate can then be set on the basis of this information relating to the state of the chain.
A preferred embodiment of the present invention will be described in the following, with reference to the accompanying drawings.
The transport device 100 according to the present embodiment, by way of example, comprises a plurality of transport apparatus 104 which can move along the first direction, indicated by an arrow in
In the embodiment by way of example, shown in
In the embodiment, by way of example, that is shown, a marking 110 is applied to the side of some of the transport elements 104. It should be noted that, in the embodiment shown, a marking 110 is not applied to every transport apparatus 104, but an embodiment in which a marking 110 is applied to every transport apparatus 104 is also possible. The marking 110 comprises a pattern 112.
Furthermore, it should be noted that, in the embodiment by way of example, the transport device 100 displays exactly one workpiece 102, but in particular embodiments are possible in which a plurality of workpieces 102 are transported and/or processed simultaneously on one transport device 100.
The embodiment, by way of example, of the present invention shown in
The transport device 100 further comprises a plurality of support means 116, one of which is shown by way of example in
The transport device 100 further comprises a board encoder (position switch) 122, which outputs a signal in the event of mechanical contact between a workpiece and a movable component on the upper face.
A path A1 denotes a spacing, measured in the first direction, between the reference point 120 of the workpiece and a reference point 124 of a marking 110.
It should be noted that in principle every marking 110 and every workpiece 102 comprise a reference point, which is located in each case at the frontmost end thereof in the first direction. For reasons of simplicity of illustration, however, only two of such reference points 120, 124 are shown in the embodiment, by way of example, shown in
The spacing A1 between a reference point 124 of a marking 110 and a reference point 120 of a workpiece 102 can be determined for example in that a measuring signal of a sensor means 114 at which the sensor means 114 registers that a front end of a marking 110 is moving past it, is compared with a signal of the position switch 122 which is output when the front end of a workpiece 102 moves past it and actuates the movable component on the upper face.
It should be noted that, although in
A second spacing A2 denotes the spacing between a reference point (not shown) of the sensor means 114 and a reference point (not shown) of the processing device 118. Even though the reference points can in principle be selected freely, and methods for converting distances in various reference systems are known to a person skilled in the art, in the embodiment by way of example the reference points are expediently the position of the measurement system in the first direction, at the level of which the sensor is located, and the position of the processing device in the first direction, at the level of which the tool is located.
Furthermore,
Furthermore,
For the sake of easier traceability, reference is made in the following to black 302 and white 304 regions. In the detail of the incremental pattern 301, shown in
Furthermore, an item of information which specifies a distance between a reference point 124 of the marking (not shown in
The incremental pattern shown in
The embodiment shown in
Within the meaning of this invention, reference is made to an incremental scale if at least one length of the length of the black regions L102 along the first direction or the length of the white regions L104 along the first direction is the same over the entire pattern and for. In other words: All the black regions 322 are of length L102 in the first direction, and/or all the white regions 324 are of length L104 in the first direction. An exception, in which the length L102 of the black regions 322 in the first direction is equal to the length L104 of the white regions 324 in the first direction, is shown in
In the embodiment by way of example, shown in
For example, the sensor device can carry out a counting step every time a black region 322 passes through, such that, with knowledge of the length of each black region L102 in the first direction, and knowledge of the length of each white region L104 in the first direction, and the number of black regions passed through in the first direction, a spacing with respect to the first back region 322 can occur, wherein the accuracy or the resolution of the position determination increases with a decrease in length of the black regions 322 and of the white regions 324 in the first direction. On the basis thereof, it is possible to calculate the spacing in the first direction, between the sensor device and the reference point of the marking. On the basis thereof, and on the basis of knowledge of the spacing A1 between reference point 120 on the workpiece 102 and reference point 124 on the marking 110 in the first direction, as well as knowledge of the spacing A2 between a reference point on the sensor means 114 and a reference point on the processing device 118 in the first direction, it is thus possible to determine the relative position between a reference point on the processing device 118 and a reference point on the workpiece 102.
In the embodiment shown in
In a first step S1, a marking of a transport unit is read out. The reading out can for example include optical reading out of an incremental pattern or of an incremental scale.
In a second step S2, the information obtained from the reading out is processed; for example image data from an optical sensor unit are processed and edited such that optical structures can be identified, or magnetic field changes of a magnetic marking are converted into electronic data.
In a third step S3, a comparison is performed.
In the case of an incremental pattern as shown in
In a fourth step S4, a position determination is carried out on the basis of the results of the comparison.
In the case of an incremental pattern, this position determination can include, for example, a determination of a recorded region of the pattern, which is followed by a determination of the spacing of a point of the recorded region from a reference point 124 of the marking 110. A distance of the reference point 124 of the marking 110 from a reference point of the sensor means 114, in the first direction, results. The position of the reference point of the workpiece 102 relative to the reference point of the processing device 118 can now be determined, on the basis of the spacing between the reference point 124 and the sensor means 114 in the first direction, and of the known spacing between the reference point 120 on the workpiece 102 in the first direction and the reference point 124 on the marking 110, and of the known spacing between a reference point of the sensor unit 114 and a reference point of the processing device 118 in the first direction.
In the case of an incremental scale, this position determination can for example contain a determination of a number of increments passed through (i.e. for example black 322 or white 324 regions in
Following the position determination step S4, the position determined in the position determination step can be provided as information; for example it can be transmitted to a control unit (not shown) which controls the processing device 118 on the basis of the transmitted information.
Following the position determination step S4, in the embodiment by way of example in
Following the storage step S5, the method can be performed again, beginning with the read-out step S1, wherein the stored information relating to the position of the transport apparatus 104 can be used for example as a basis for the comparison in step S3, such that it is possible to determine a current position, with respect to a fixed reference point, on the basis of the comparison of the change in a current position.
A method for determining the position of a workpiece 102 in a transport device 100 according to a further embodiment by way of example can be illustrated with reference to
In an embodiment, by way of example, of the present invention that is not shown, the workpiece can be processed using a tool, on a transport device in a processing device 118. The workpiece can for example be milled, sawn, or chamfered. In the embodiment by way of example the workpiece 102 can be moved relative to the tool, in the processing device 118.
According to the embodiment described above, with knowledge of a relative position of the tool with respect to the transport device 100 along the first direction, and knowledge of a relative position of the workpiece 102 with respect to the transport device 100 in the first direction, it is possible to determine the relative position of the workpiece 102 with respect to the tool, using the above-described method for position determination.
Number | Date | Country | Kind |
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10 2019 110 568.4 | Apr 2019 | DE | national |
Filing Document | Filing Date | Country | Kind |
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PCT/EP2020/061307 | 4/23/2020 | WO |