FI84709C - ANORDNING I TRAEBEARBETNINGSMASKINER. - Google Patents

Description

1 84709

The invention relates to a device in woodworking machines and the like, in which the workpiece passes through the machining blades forming a stationary machining area and the workpiece slides in this machining area on at least one surface of the workpiece. to control the stability of the distance of the machined surface. In particular, the invention relates to machine tools for parquet boards and other similar pieces of wood, in which control for machining is taken from one straight surface of the piece.

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In the manufacture of, for example, parquet boards, board blanks are first made, the surface of which, which becomes the final visible floor surface, is ground, after which the parquet board blanks are fed to a machine tool which mills the two left-20 edge edges of the board into one male tongue and another female tongue. The machine tool is typically constructed such that the board blank is made to run in its longitudinal direction so that the ground surface corresponding to the final outer surface of the board blank slides along the sliding surface of the abutment path 25 belonging to the machine tool. The tight contact between the surface of the board blank and the sliding surface is ensured by pressing rollers which press the board blank against the sliding surface. In this case, the cutter blades that process the edges of the board blank can be set to the correct positions. In such a parquet board, the most demanding and most accurate measure of its dimension is the distance of the tongue from the exposed surface. Namely, such parquet boards are used pre-treated, in which case they are not sanded or otherwise treated at the installation site, but are only joined to one another 35 of their points. In this case, even a small dimensional error in the position of the tongue from the top surface of the board causes the top surfaces of the connected boards not to come to the same level, but a small threshold is formed at their boundary point, which cannot be allowed on the floor. The maximum permissible deviation 40 2 84709 between the surfaces of two adjacent boards is of the order of 0.1 mm, but it is generally preferred that the difference be less than 0.05 mm or the like.

5 Achieving the accuracy described above in continuous series production for each parquet board and length must be ensured. Since the central thickness region of the parquet board to which the joints normally enter is made by gluing the slats, the surface of the joints is uneven when viewed from a short distance 10, with the result that measuring the position of the joints with conventional measuring devices is not possible and the result is misleading. In addition, such a measurement would easily be affected by the same error factor as in machining, i.e. contaminant particles such as detached wood sticks, sawdust, grinding dust piles and the like, the presence of which in a woodworking plant cannot be avoided. These cause, in the event of a stop between the sliding surface and the parquet board to be machined, the board to rise off the sliding surface at least some distance, resulting in a shift of 20 points from the board surface even if the blades themselves are perfectly mounted relative to the sliding surface. If a particle causing the board blank to detach from the sliding surface gets stuck somewhere on the sliding surface, this will almost certainly result in scratches or scratches on the already sanded surface of the board that runs against the sliding surface. This in turn causes the board or boards in question to be discarded before forwarding. Since the joints have already been machined in such a piece, the board blank in question cannot even be re-sanded, but is directly 30 production wastes. For this reason, any means that would have broken the continuity of the sliding surface, such as devices measuring from this surface, such as mechanical measuring devices, which could have collected dirt particles or which could be caught by the dirt particles, has been avoided. As the impurity particle-35 travels with the board blank, the measurement error caused by the particle extends to some distance from its location in both directions, with the result that the board blanket may not be out of tolerance along its entire length. Especially if the defect is only at the other end of the board blank, a usable product can still be obtained from the blank by cutting off the defective point as long as it is known which point or points of the boards are within the tolerances 5 and which points are not. This has not been possible by known means.

It is therefore an object of the invention to provide a measuring device, in particular for woodworking machines, which can detect the exact distance of an uneven surface of a workpiece from one other surface and which for this purpose, especially in the working blade range, indicates that the surface of the workpiece is tightly against the sliding surface. the surface of the body detaches from the sliding surface 15 by said small tolerance dimension. The object of the invention is to provide a measuring device of this type which is also able to show only the detachment of one edge of the body from the sliding surface, even if the other edge is still properly attached to the sliding surface. It is also an object of the invention to provide a measuring device of the type described above, which makes it possible to keep the sliding surface of the response as a uniform uninterrupted surface which cannot be adhered to by harmful particles. In addition, it is an object of the invention to provide a measuring device of the type described above which provides means for retrospectively separating those parts from machined parts where the parts have come off the sliding surface and is also capable of giving an alarm if necessary to stop the machine.

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By means of the device according to the invention, a decisive improvement in the presented drawbacks is achieved and the defined objectives are achieved. To achieve this, the device according to the invention is characterized by what is set forth in the characterizing part of claim 1.

In particular, the invention has the advantage that the device indirectly makes it possible to detect the exact distance of a tongue surface or other machined surface corresponding to an uneven surface, and in particular the deviation from this distance, simply without mechanically moving parts. Another advantage of the invention is that its further development has erroneous portions of the product significant for subsequent removal. In addition, the invention has the advantage that the device can also be retrofitted to existing plants and has a simple and reliable structure.

The invention will now be described in detail with reference to the accompanying figures, in which Figure 1 shows a cross-section of a device according to the invention along the plane I-I of Figure 2 and Figure 2 shows a side view of a device according to the invention in the direction II of Figure 1.

The figures show in principle a machine tool 1 for a parquet board or an ordinary board in general. This machine tool 20 has a stop path 2, which in Fig. 2 is shown in its longitudinal direction and in Fig. 1 in cross section. The workpieces 3 are fed to the machine 1 along this abutment path so that the pre-ground or otherwise pre-machined surface 4 of the workpiece 3 is pressed against the sliding surface 5 of the abutment path. Figure 2 pass through the processing region and the direction of the arrow S occurs through machining of the blades not shown devices, and this means in Fig 1 on the plane perpendicular to the direction. The workpieces 3 are pressed against the sliding surface 5 of the abutment path 2, for example by press rollers 30 6, which may be several in succession in the workpiece direction S, but generally in at least two places and in parallel, i.e. one, two or more transversely to the direction S. Likewise, the width of the rollers can vary from quite narrow to the width 35 of the entire abutment path, and their compression is adjusted in a manner known per se, not shown here, to obtain the desired surface pressure between the workpiece surface 4 and the sliding surface 5. In any case, the pressing of the workpieces 3 takes place on the workpiece surface 5 84709 4, which thus comes against a substantially parallel surface 7 opposite the sliding surface 5. In addition, the machine tool of course has machining blades, in this case blades 8 and 9, adapted to machine the elongate workpiece. to the longitudinal edges of the female tongue 10 and the male tongue 11, respectively. The machining blades 8, 9 remain stationary with respect to the abutment path 2, except for the actual machining movement, and thus form a fixed or stationary machining area. The machining area 10 here means the area between the planes perpendicular to the direction of movement S through the extremes formed by the machining blades during the machining movement, which is indicated by T in Fig. 2, because in this case the machining movement is rotation of the blades, but the blade axes remain stationary.

When considering a finished product to be made of a workpiece, in this case a parquet board, i.e. in this case a floor, it is essential for the appearance and usability of the floor 20 that the joints 10 and 11 are at exactly the same and correct distance from the surface 4, which makes the finished floor visible. upper surface. For the sake of simplicity, the distance of the tongues 10, 11 from the surface 4 is expressed here only by the distance H from the surface 4 of the tongue groove upper surface 12 and the tongue protrusion 25 and this distance H must be equal on both the female and male tongue sides and the same size on all parquet boards. . Of course, the other dimensions of the joists must be correspondingly equal to 30, only in this way will the finished floor become flat without any steps arising at the joints of the boards.

Since the accuracy requirement for the dimension H is very high, as described above, even small debris, such as a grinding-35 dust deposit, a stick detached from the end of the board or a sawdust particle if it gets between the board surface 4 and the sliding surface 5, causes an unacceptable error . This situation is shown in the figures with a dashed line and greatly exaggerated to clarify the matter. Figure 1 shows how the board has increased by dimension D due to debris, i.e. the distance between the board surface 4a and the sliding surface 5 is this dimension D, whereby the distance between the upper surface 12, 13 and the raised board surface 4 has decreased to H-D. Figure 2 shows from the side how such a situation can arise when there is debris either in the machining area or below the front edge of the workpiece 3, which raises the end of the board in the area between the press rollers 6. Such and other corresponding protrusions 10 of the workpiece 3 from the sliding surface 5 cannot be completely prevented by control means, because the compression of the workpiece 3 against the abutment path 2 cannot be increased too much due to the heating between them and the limited compression resistance of the workpiece. In addition to this, it is not always possible to arrange the press rolls in the machining area, depending on the position, size, etc. of the blades to be machined.

The invention is based on the fact that the positions of the sliding surface 5 of the abutment path 2 and the machining blades 8 and 9 relative to each other 20 can always be set and locked with sufficient accuracy. Thus, the measurement errors in the final products are not due to the machine tool, or if they are, the error is systematic and immediately detectable by sampling, but are due to the dirt particles or the like just described. Thus, the principle of the invention is that the dimensional accuracy of the product can be ascertained by measuring the ratio between the workpiece and the machine and if there are deviations, it is also a clear indication that the final product deviates from the required size and surface quality with moderate probability.

Thus, in the invention, the position of the workpiece and the deviations from the sliding surface 5 are selected as the measuring object.

According to the invention, the distance of the surface 4 of the workpiece 3 from the surface 5 of the slider 35 is measured by one or more optical distance measuring sensors 14 directed below the abutment path 2 through it towards the surface 4 of the workpiece 4 when the sensors 14 are attached to the machine tool. 2 so that the sensors 14 are immobile and fixed with respect to the path, the sensors 14 indicate with a certain signal value the position 4 of the workpiece 3 against the sliding surface 5 and with a different signal value 5 indicate that the surface 4 has detached from the sliding surface 5, since the surface 4 is from the sensor and thus from the sliding surface. The optical rangefinders 14 may be of any commercially available type 10 suitable for the purpose and their construction will thus not be described very precisely. They typically internalize a supply circuit 15 for driving a light emitting diode or laser 16, a light directing lens 17, receiver lenses 18, an optical position detector element 19 and an amplifier circuit 20. The sensor 15 operates so that the optical position detector element detects a change in the incident angle in the detector corresponding to the changed position of the object. Figure 1 shows an emitted beam 24 on each sensor 14 impinging on the surface 4 20 and three assumed reflected beam 25 corresponding to three assumed target positions, clearly showing how a change in the position of the object affects the incident beam at the detector 19. This change in position can be converted to a surface 4 to a distance change which takes place behind the sensors 25, e.g. in a control unit 21 connected by a cable 31. This control unit 21 is further connected at one output 32 to a roller stamping unit 22, which can also be of any known commercially available type, so its structure will not be described in more detail here. However, the roller stamping unit 22 includes a marker roller 23 indicated in the figures by a solid line in a non-marking position at a distance M from the workpiece top surface 7 and by a dotted line at a marking position in contact with the workpiece top surface 35 7. a relatively continuous character for as long as printing continues. The transfer of the marking wheel 23 from the rest position to the marking position is indicated by the arrow M. In addition, the control unit 8 84709 21 can be connected from its second output 33 to another alarm device, monitoring device, printer or other object requiring information. The marking roller is usually not on the guide surface or on the side 4 but on the other sides of the piece 3 5, i.e. on the sides 7, 30a, 30b, because the side 4 is usually pre-machined and it is desired to keep it clean.

The device according to the invention works as follows: 10 The device is calibrated after installing the sensors 14, always after maintenance or when changing the product if the color or roughness of the product surface 4 changes significantly or otherwise, if necessary, to check the device, normally placing the part corresponding to the product 6 by pressing against the sliding surface 5, thus ensuring that the surfaces are clean so that the surface 4 comes tightly against the surface 5. In this case, the signal levels of the device are adjusted from the control unit 21 and the distance of the body surface 4 from the sensor to the base plane is calibrated, corresponding to the fact that its distance 20 from the sliding surface is zero. In this case, one or more alarm limits for dimension D can also be calibrated, i.e. there are several dimensions to be considered such as D1, D2, etc. At its simplest, marks the workpiece as far as the alarm limit is exceeded. In addition, the device can give an audible signal or other signals to the user of the machine. It is also possible to use two alarm limits, the smaller deviation of which, i.e. a lower value of 30 D (e.g. D1) causes a marking on the roller 23 and for example printing on a computer screen and a higher alarm limit (e.g. D2, where D2> D1) beeps or even stops production . A time limit can also be programmed for the alarm, i.e. exceeding the limit value D for a period longer than the specified time period 35 causes a different alarm than a short temporary exceeding of the limit value. This helps to act according to the severity of the error.

9 84709

Since there should be no discontinuities in the sliding surface 5 of the abutment track 2, as previously described, glass windows 26 are placed between the sensor 14 and the surface 5, through which the outgoing measuring beam 24 and its return rays 25 pass.

The windows 26 are either glass or an organic polymer or the like which passes the wavelength of the measuring beam without diffusing it. The upper surfaces 27 of these windows 26 are either mounted very precisely flush with the sliding surface 5 or ground after installation to the same level 10, and further the connection between the windows 26 and the abutment track 2 is sealed at least in the vicinity of the sliding surface 5, for example by sealing compound 28. ice and no impurity collecting gap is created. For this purpose, the windows 26 may be threaded, the threads being sealed with a suitable mass or the windows glued directly or cast directly from a suitable material into the opening of the abutment track or in another suitable manner. Another possibility is to make the entire abutment path from a uniform glass or ceramic material 20, in which case the actual windows in the sense described above are not required or these are structurally the same material as the abutment path. If the abutment path 2 is made entirely of transparent glass or the like, it may be necessary to cover the non-functioning lower surface 34 and the sides 29 of the abutment path with an opaque coating or housing so that light from outside does not interfere with the measurement. It is also conceivable that the abutment path is made of clear non-diffusible glass or plastic only at the windows 26 and elsewhere the same material 30 dark colored or otherwise impermeable to impermeable.

Although woodworking machines have been discussed above, the invention is applicable to all machine tools in which the accuracy of the machining is based on the fact that the blades in the machining area move along the sliding surface of the machine while stationary except for the machining movement. In particular, the invention is suitable for use in the control of products in which a point requiring accuracy is at least 10 84709 slightly uneven when viewed, making local measurement unreliable.

Claims (7)

11 84709 A device in woodworking machines and the like, in which the workpiece passes through the machining blades (8, 9) forming a stationary machining area and the workpiece 5 (3) slides in this machining area on one surface (4) along the sliding surface (5) of the machine tool abutment (2) , for monitoring the stability of the distance between at least two surfaces of a sliding workpiece machined here, characterized in that the device comprises an optical distance measuring sensor (14) known per se, located in or near the machining area below the sliding surface (5) of the abutment path (2) from the interface between the part directed towards the side (4) of the workpiece (3) which is against the sliding surface, measures the distance of this side, and that at least the part (26) between the sliding surface (5) and the sensor (14) is formed background material (24, 25) of permeable material, the upper surface (27) of which is sa with the sliding surface, to indicate close contact of the workpiece and the sliding surface and their release in the machining area, respectively. Device according to claim 1, characterized in that the sensor (14) is mounted on the counter track (2) so that the sensor cannot move during operation, and that the device comprises a control unit (21) which is calibrated to give a first signal or alternatively does not to give a signal when the moving workpieces (3) are at a predetermined accuracy against the sliding surface (5) and thus at a predetermined fixed distance from the sensor, and to give another signal such as an alarm or the like whenever the moving workpiece (3) is at a distance (D) from the sliding surface (5) is greater than a predetermined limit value corresponding to an increase in the distance of the workpiece from the sensor at this limit value. Device according to claim 2, characterized in that the device comprises a roller stamping unit (22) adapted to mark the movable workpiece (3) on a side (7, 30a, 30b) other than the side facing the sliding surface 84 709 1a, when the control unit (21) gives said second signal. Device according to Claim 1, characterized in that the part (26) between the sliding surface and the sensor is made of inorganic glass, which is fastened to a counter track (2) of other material and the edges of which are sealed (28) at least at the sliding surface (5). ; or said part (26) is an organic polymer fixed as mentioned above or cast in place. Device according to Claim 4, characterized in that the part (26) between the sliding surface and the sensor is ground after installation with its surface (27) pointing towards the workpiece (3) in the same plane as the sliding surface (5) of the abutment path. Device according to Claim 1, characterized in that the abutment path (2) is made entirely of glass or ceramic, which is either completely or only permeable to the measuring radiation at the sensor (26) without diffusion. Device according to claim 6, wherein the abutment path itself is permeable to measuring radiation, characterized in that the abutment path (2) is light-impermeable coated or encapsulated on its sides (28, 29) remote from the sliding surface (5) so that light from outside cannot be affected. the measurement result. i3 84709