Patent Publication Number: US-6220315-B1

Title: Method for machining workpieces

Description:
This application is the national phase of international application PCT/DE98/01151 filed Apr. 24, 1998 which designated the U.S. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Technical Field of the Invention 
     The invention relates to a method for processing workpieces which are supplied to a processing area, are processed there on one side, are moved out of the processing area, are turned and are again supplied to the processing area for processing the second side. 
     Processing methods within production installations—for example of the wood-processing industry in the sector of “dovetail joint installations”—are sufficiently known. However, all of these have the disadvantage that, when using only a single processing machine—for example dovetail joint machines—, which is supplied by means of a forward feed device for producing a workpiece or workpiece package which is finished on both ends, an unproductive, time-consuming return of the empty forward feed device for being again loaded with work pieces is always required. 
     2. Prior Art 
     A typical example of such a method is known from the species-defining Laid-Open Application 43,10,399. The subject of this laid-open application is a combination of forward feed movements with turning movements, wherein the turning movement is required for moving the two spaced-apart or oppositely-located workpieces, which are respectively to be processed, to the processing station. A work table is used for this which, with workpieces placed on it, is moved past end-processing tools 3 and 4, and in the process performs a pendulum movement between a starting position and an end position. 
     It is of particular disadvantage, that the return of the work table here also takes place empty, i.e. without a workpiece on it, because a very elaborate turning device (FIG. 2 in 43,10,399), which can be displaced on several work levels, is required outside of the work table 1, which also contains devices, with whose aid the return trip of the workpiece which was processed on one side, to the starting position of the work table 1 takes place. Thus, while the worktable returns idle, and therefore without doing useful work, the elaborate turning of the workpiece, which was processed on one side, is performed parallel with this. 
     BRIEF SUMMARY OF THE INVENTION 
     It is the object of the invention to design such known processing methods simpler and more efficiently. 
     In accordance with the invention, this object is attained by supplying a first workpiece that has already been processed on the first side together with a second workpiece that has not previously been processed on the first side or the second side to the processing station; processing the second side of the first workpiece and the first side of the second workpiece in one processing operation in the processing station; and individually moving the first workpiece on following the one processing operation, whereby during each processing operation a workpiece processed on both sides is created together with a workpiece processed only on one side. 
     The unproductive return movement of the forward feed device (corresponding to the work table 1) is avoided in that, in accordance with a preferred embodiment of the object attained by the invention, the forward feed device itself is turned between successive work cycles and therefore is also used for the return transport of a workpiece with a front face processed on one end. Here, the forward feed device V performs a double function in that it performs the processing forward feed, turning of the workpiece and return of the workpieces processed on one end, functions, which must be performed by separate devices in connection with the subject of the Laid-open application 43,10,399. 
     Thus, by means of the method in accordance with the invention, the return trip of the forward feed device (corresponding to the work table 1 of Laid-open application 43,10,399) in particular is also actually used. 
     In accordance with a further advantageous embodiment it is also not important whether individual workpieces or a workpiece package formed by identical workpieces is employed, but instead, that during each processing operation (i.e. each forward feed of two workpieces or workpiece packages to the tools K), a respective workpiece or workpiece package, whose first side is being processed, is located on the forward feed device V, and a workpiece or workpiece package, whose second side is being processed or, in simpler terms a pair of workpieces or workpiece packages with altogether an uneven number of processed sides, lies on the forward feed device before or after each processing operation. In the exemplary embodiment of the invention represented (FIG.  5 ), there are three such processed sides. In contrast thereto, with comparatively the same outfitting in pairs, there is always a pair of workpieces with an even number of processed sides, i.e. a total of two or four processed sides, located on the worktable of the subject of Laid-Open Application 43,10,399. 
     With the embodiment of the method in accordance with the invention, at least two workpieces and/or workpiece packages, which are separated from each other, are always located in the forward feed device, or respectively its transport devices. In the process, one of them is processed for the first time, i.e. afterwards it has been processed only on one side, but another workpiece or workpiece package is already finished on both sides after each processing operation. 
     Thus, the advantage over the known method lies in that—except for the first processing operation when the production installation is started up—during the entire running time of these installations, at least one workpiece or workpiece package which is finished on both sides, is produced in every further processing operation. An unproductive return of empty forward feed, or respectively transport devices, is avoided here, therefore a workpiece of workpiece package which is finished on both sides, is created during each processing operation. 
     This means a considerable shortening of the production times of the workpieces/workpiece packages, and therefore a meaningful productivity increase of the entire production installation. 
    
    
     BRIEF DESCRIPTION OF THE SEVERAL VIEW OF THE DRAWINGS 
     A preferred exemplary embodiment of the method in accordance with the invention will now be explained by means of the drawings and a function description; shown are in: 
     FIG. 1, a plan view of the device intended for executing the method of the invention in the course of delivering a first workpiece, 
     FIG. 2, a plan view in accordance with FIG. 1 in the course of performing a processing operation on the first side of the first workpiece, 
     FIG. 3, a plan view in accordance with FIG. 1 after turning the first workpiece by 180°, 
     FIG. 4, a plan view in accordance with FIG. 1 after the return movement of the forward feed device and in the course of supplying the second workpiece, 
     FIG. 5, a plan view in accordance with FIG. 1 after the performance of the next processing operation on the second side of the first workpiece and the first side of the second workpiece, and 
     FIG. 6, a plan view in accordance with FIG. 1 after turning the second workpiece by 180°. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The first workpiece package W 1  consisting of any arbitrary number of workpieces—hereinafter called “workpiece”—rests on a conveyor belt T 1 . From there, it is passed in the direction H to a conveyor belt V 1  of the forward feed device V, which is in a standby position in position  1 . 
     The forward feed device V now moves in the direction P and feeds the first workpiece W 1  to be processed to the processing tools K (FIG.  1 ). 
     The forward feed device V stops in the position  2  at the end of the processing operation; the first side W 1 A of the first workpiece W 1  has now been processed. The forward feed device V is now turned by 180° around its vertical axis (Z) (FIG.  2 ). 
     Because of the turning of the first workpiece W 1  resulting from the turning of the forward feed device V, the unprocessed second workpiece side W 1 B, as shown in the broken line position of FIG. 3, now lies in the effective range of the tools K and therefore can be processed in the next processing operation. The forward feed device V moves back in the direction R and stops in position  1  (FIG.  4 ). 
     Now the second workpiece W 2  is supplied to the transport device V 2  by the transport device T 1 . The forward feed device V now again moves in the direction P and conducts the workpieces W 1  and W 2  together to the processing tools K (FIG.  4 ). 
     At the end of the processing operation in the processing station, the forward feed device V stops in the position  2 . Both sides W 1 A and W 1 B of the first workpiece W 1 , as well as the first side W 2 A of the second workpiece W 2  have now been processed. 
     The first workpiece W 1  is now finished and is conducted in the direction Y to the transport device T 2 . Because of this, the transport device V 1  of the forward feed device V is empty (FIG.  5 ). 
     The forward feed device V now again is turned around its vertical axis Z by an angle of 180°. 
     Because of the resultant turning of the second workpiece W 2 , its unprocessed second workpiece side W 2 B now lies in the effective range of the tools K and therefore can be processed in the next processing operation. 
     The forward feed device V again moves in the direction R back to the position  1  and the above described processes, represented in FIGS. 3 and 4, are now repeated again (FIG.  6 ).