Patent Publication Number: US-6712198-B2

Title: Articulated arm transport system

Description:
The invention relates to a transport system for transporting workpieces from a machining station into the next machining station or intermediate store of a press, press line, simulator, or the like. 
     PRIOR ART 
     Where the manufacture of a workpiece calls for a plurality of work operations, such as cutting or shaping, then for economic production the necessary individual operations are carried out in a transfer press or press line, as they are known. The number of tools then corresponds to the number of work stages which are necessary for the manufacture. In the presses there are transport devices with which the workpieces are transported from one workstation to the next. 
     In the case of transfer presses or large-component transfer presses, the transport devices comprise gripper or load bearing rails which extend through the entire length of the shaping machine. In order to transport the components, the load bearing rails are fitted with gripper or holding elements. In this case, a distinction is made, depending on the movement sequence, between a two-axis transfer fitted with suction crossmembers or a three-axis transfer fitted with gripper elements. As an additional movement, pivoting in order to change the attitude of the component during the transport step may be required. This attitude change can also be carried out by an orientation station arranged between the shaping stages. 
     The transfer movement is initiated via cams, which are forcibly synchronized with the ram drive via movement transmission elements. The manufacture of large-area components, in particular, has led to the development of large-component transfer presses of greater and greater dimensions, based on the shaping force and the transport paths. Tool spacings of the order of magnitude of 5000 mm are entirely normal nowadays, and therefore corresponding transport steps are also necessary. 
     As a result of this development, the masses to be accelerated and braked in the transfer systems are completely opposed to the low masses of the components to be transported. Since the transport step is to be executed in an extremely short time, in order to achieve the greatest possible number of press strokes and therefore output of components, the system must have a high speed and therefore also acceleration and retardation. 
     A further disadvantage is the rigid movement sequence which is predefined by the cam drives. The optimum utilization of the free spaces between the lower and upper tool during the ram stroke to transport the parts is not possible. 
     In order to avoid these indicated disadvantages, intellectual rights applications nowadays concern the replacement of the previous transfer system by a corresponding number of transfer systems arranged between the machining stages and equipped with their own drive. Such an arrangement is disclosed by EP 0 672 480 B1. Transfer systems arranged on the uprights are equipped with a number of drives which, in operative connection with the movement transmission means, carry out the transport of the components. As a special feature, the system can be re-equipped both as a two-axis transfer with suction beams and as a three-axis transfer with grippers. However, this universal use requires a corresponding outlay on construction. 
     Likewise arranged in each upright area is a transfer device disclosed by DE 196 544 75 A1. In this application, elements which are known as—parallel cinematics—are used for the drive. In a modification of these known movement elements, however, telescopic lengthening of the drive rods is not performed, but, with a constant rod length, the attachment points are changed and therefore the transport movements are achieved. The attachment points that accommodate the forces or torques are not constant in terms of their distance from one another and, in particular when these points are close to one another because of the desired travel curve, support problems can occur. In order to increase the stiffness of the system, further mutually parallel links are also proposed, which are connected to one another by transverse crossmembers. In order to achieve functionally reliable transport of large-area components, the proposed system becomes correspondingly complicated and has a large overall height. 
     In DE 100 10 079, not previously published, the applicant proposes a system having transport devices arranged in the press upright area, which operate in a way comparable with a pivoting-arm principle. Crossmembers which are provided with component pick-up and holding means and are arranged transversely with respect to the transport direction are in each case held and moved at their ends by these pivoting-arm robots. Thus, the pivoting-arm robots are in each case arranged in pairs and opposite each other in the upright area. Because of the overall height and the vertical movement required by the drive concept, the transport system proposed is in particular suitable for presses with a relatively large overall height. The pivoting arm comprises a rigid piece which results in a correspondingly large pivoting radius. Since the intention is for the workpieces to be removed at the earliest possible time after the start of the ram upward movement, the large pivoting radius and the resulting obstructing edges are unfavorable. With this system, a desirable flat entry or exit curve can be implemented only with difficulty. 
     OBJECT AND ADVANTAGE OF THE INVENTION 
     The invention is based on the object of providing a highly flexible and precise transport system with a low overall height which ensures advantageous utilization of the free movement between the upper and lower tool for the purpose of insertion and removal of workpieces. 
     The invention is based on the idea, instead of using a rigid transport system, to design the latter from two parts which are connected to each other, mounted in an articulated fashion. In order to achieve a flat entry and exit curve, the pivoting angle of the first part arm can be selected to appropriately large. 
     On the basis of the proposed design, in conjunction with controlled drives, the pivoting angle can be selected within any technically practical range. As a result, in the tool area the transport arm is located in a very flat attitude oriented toward the horizontal plane. 
     Thus, with a relatively small opening stroke of the press ram bearing the upper tool, the articulated arm can advantageously move into the clearance which forms between the upper and lower tool. 
     Particularly advantageous is a design of the two articulated arm parts with equal lengths, since then a horizontal transport movement is executed. The suction spider carrying the workpiece therefore carries out a distortion-free horizontal movement. The vertical movement necessary to deposit and raise the workpieces is executed by a stationary lifting drive. 
     Given superimposition of the horizontal and the vertical movements, an appropriately beneficial flat curve course can be implemented at the start and end of the transport movement. The large-component transfer press or press line can be run without difficulty with phase-shifted ram positions, which results in a beneficial force distribution with a low drive power. This measure likewise increases the component output by reducing the transport times. 
     During the actual shaping operation, the articulated-arm transport system should be located in a lowered position in the upright area, as a result of which beneficial accessibility to the rising ram is provided for the following component transport. This accessibility permits an early inward movement and, as a result, in addition reduces the idle times. This lowered parking position is also made possible by superimposing the horizontal and the vertical movements. 
     Depending on the task set, it may be necessary for the attitude of the components to be changed between two shaping stations. In a press line, the attitude change takes place by means of intermediate stores, orientation stations as they are known. Since the intermediate stores lead to an enlargement of the overall press length, attempts are made to avoid this solution in the case of large-component transfer presses. When used in a large-component transfer press, if required, the articulated-arm transportation system is designed with an additional pivoting movement. 
     The installation position of the articulated-arm transport system is any desired, that is to say the pivoting movement can be carried out both above and below the transport plane. 
     Further details and advantages of the invention emerge from the following description of exemplary embodiments. 
    
    
     In the seven figures, in schematic form: 
     FIG. 1 shows a press line with an articulated-arm transport system 
     FIG. 2 shows a large-component transfer press with an articulated-arm transport system 
     FIG. 3 a  shows a detail of the articulated arm drive 
     FIG. 3 b  shows an individual unit [sic] of pivoting the transverse crossmember drive 
     FIG. 4 shows a plan view of FIG. 3 a  and FIG. 3 b    
     FIG. 5 shows a detail of pivoting the articulated arm without a transverse crossmember 
     FIG. 6 shows a plan view of FIG.  5 . 
    
    
     DESCRIPTION OF THE EXEMPLARY EMBODIMENTS 
     By way of example, presses  2  and  3  from a press line  1  are illustrated in FIG.  1 . Press rams  4  and  5  carry upper tools  6  and  7 . Lower tools  8  and  9  are located on sliding tables  10  and  11 . Arranged between the presses are orientation stations  12  and  13 . On the press uprights  14 - 17  there are the articulated-arm transport systems  18 - 21  according to the invention, in different functional positions. Vertical guide rails  22  are fixed to the press uprights  14 - 17 , carriages  23  with guides  24  carry the articulated arms  43 ,  44 . The drive motor for pivoting the arm is designated by  25 . The stationary lifting motor  26  for the vertical movement is operatively connected via a gear  27  to a rack  28 . More detailed constructional details will be described in following figures. The task of the articulated-arm transport system  18 - 21  is to convey components cyclically in the transport direction  29  through machining and orientation stations arranged one after another. The various movement sequences are not illustrated chronologically but by way of example. 
     In order to load the first press  2 , the component holding means  31 , for example suction spiders, fixed to transverse crossmember  36  [sic] and belonging to the articulated-arm transport system  18  pick up panels  32  from a panel stack  33 . A shaped part  34  is removed from the opened press  2  by the articulated-arm transport system  19  and transported to the orientation station  12 . Articulated-arm transport system  20  inserts a component  35 , which has previously experienced an attitude change in the orientation station  12 , into press  3 . Articulated-arm transport system  21  in turn deposits a component  36  shaped in press  3  onto the orientation station  13 . The travel curve for the component transport is identified by  37 , that for the parking position by  38 . In this application, pivoting of the components by the articulated-arm transport system is not provided and, if required, is carried out by the orientation stations  12 ,  13 . 
     In each case the articulated-arm transport systems are arranged on the press uprights in pairs and opposite each other in mirror-image fashion. Pick-up elements for the transverse crossmember  30  carrying the component holding means  31  are configured in such a way that automatic replacement at a tool change is possible. 
     The shaping of the articulated arm, which is particularly beneficial in order to utilize the free accessibility between the upper and lower tools, can easily be seen. In addition, the travel curves  37 ,  38  clearly show the beneficial conditions for very flat insertion and removal of the parts. Superimposition of the vertical movement by means of the lifting drive  26  on the horizontal movement of the pivoting arm actuated by the drive motor  25  results in very advantageous movement sequences. 
     In addition, the proposed lowered parking position benefits early insertion into the tool clearance. 
     FIG. 2 shows the arrangement of an articulated-arm transport system in a large-component transfer press  39 . Illustrated by way of example are shaping stages in different movement sequences. In order to reduce the overall length of the press, intermediate stores or orientation stations have been omitted. If a change in the attitude of the component is necessary, this is carried out directly by the articulated-arm transport system. For this purpose, use is made of a drive  40 , which is connected via drive elements to the transverse crossmember  30 . The functional sequences are comparable with those already described under FIG.  1 . 
     FIG. 3 a  and FIG. 3 b  show an articulated arm in enlarged form in front view. For the purpose of simplification and better clarification, the illustration has been selected such that the drive chain for the pivoting arm can be explained in FIG. 3 a , and the drive for pivoting the transverse crossmember  30  can be explained in FIG. 3 b . In addition, reference is made to FIG. 4 for an understanding of the function. 
     It is possible to see the vertical guide rails  22  and the carriage  23 , which can be moved in guides  24  and carries the pivoting arm. The vertical movement is effected by the stationary lifting motor  26 , which drives the gear  27  that is operatively connected to the rack  28 . In order to pivot the articulated arm, according to FIG. 3 a  use is made of the drive motor  25 , which drives gear  41 . The gear  41  drives rack  42 , which is permanently connected to the first pivoting-arm part  43 . This connection effects the pivoting movement of the first pivoting-arm part  43  about the axis of rotation  69 . A further drive train is used to pass on the pivoting movement from the first pivoting-arm part  43  to the second pivoting-arm part  44 . For this purpose, there is a first gear  45  in the first pivoting-arm part  43 . This gear  45  is permanently connected to the carriage  23 . The gear  46  meshes with the gear  45 , and the gear  47  meshes with said gear  46 . The gear  47  is permanently connected to the second pivoting-arm part  44 . If the pivoting movement of the first pivoting-arm part  43  is initiated by the drive motor  25  via gears  41 ,  42 , then this movement produces a rolling pivoting movement of the gears  46 ,  47  and, as a result of the permanent connection to gear  47 , the corresponding pivoting of the second pivoting-arm part  44  about the axis of rotation  70 . 
     The magnitude of the pivoting movement or the pivoting angle  48  can be controlled continuously via the drive  25  which, for example, is designed as a controlled servomotor. It is easy to see that the greater the choice of pivoting angle  48 , the more the articulated-arm system  43 ,  44  approaches the horizontal stretched attitude, and the smaller is the required clearance for the insertion or removal of the components. A distortion-free horizontal movement is achieved if, based on the axes of rotation or bearing axes  67 ,  70 ,  62 , the two pivoting-arm parts  43 ,  44  are designed with the same length. 
     If a change in the attitude of the components during the transport step is required as a further movement, then this can be carried out in accordance with FIG. 3 b . For this purpose, the pivoting drive  40  mounted on carriage  23  drives the gear  49 . Via intermediate gear  50 , the rotational movement is transmitted to gear  51 . Gear  51  is connected to gear  53  via a common shaft  52 . Gear  53  drives the gear train  54 - 57  mounted in the first pivoting-arm part  43 . Gear  57  is permanently connected, via a hollow shaft  58 , to toothed belt pulley  59  and drives the latter. Toothed belt pulley  59  drives toothed belt pulley  61  via toothed belt  60 . Toothed belt pulley  61  forms a unit with the pick-up and bearing unit of the transverse crossmember  30  and effects a pivoting movement about the pivot axis  62 . Since the pivoting drive  40  can also be a controlled servomotor, a defined change in the attitude of the components is ensured. 
     The pick-up and bearing unit for the transverse crossmember  30  is designed, for example, as a cardan joint  63 , which also makes possible a horizontal and vertical oblique position of the transverse crossmember  30 . Elements for the automatic change of the transverse crossmember  30  during a tool change are provided and designated by  64 . 
     The drive chains described in FIGS. 3 a  and  3   b  can be seen together from the sectional illustration of FIG.  4 . In addition to other constructional details, it is in particular possible to see the permanent connection of gear  45  to carriage  23 , required for the pivoting of the first pivoting-arm part  43 , and likewise the permanent connection of gear  47  to the second pivoting-arm part  44 . Since the opening angle between the pivoting-arm parts  43 ,  44  is twice as great as that of the pivoting angle  48 , the transmission ratio from gear  45  to gear  47  is accordingly also 2:1. The drive chain hatched more darkly in FIG. 4 is used to pivot the transverse crossmember  30  about the pivot axis  62 . 
     An embodiment without pivoting the transverse crossmember  30  is shown by FIGS. 5 and 6. The functional description of the vertical lifting movement and the gear arrangement in the carriage  23  and the first pivoting arm  43  can be taken from the previous figures. In addition, the connection of the first pivoting-arm part  43  to the second pivoting-arm part  44  via gear  47 , and the moveable mounting of the arms is constructionally identical to the embodiment already described. New is the permanent connection of toothed belt pulley  66  to the first pivoting-arm part  43 . The toothed belt drives  66 ,  67 ,  68  are now used to stabilize the transverse crossmember  30  and hold it in the correct attitude. The important factor here is that, given the selected arrangement and geometry, the belt pulley and therefore the transmission are therefore selected in the ratio 2:1, that is to say the belt pulley  68  has twice the diameter of the belt pulley  66 . Given equal lengths of the pivoting-arm parts  44 ,  43 , a satisfactory horizontal movement of transverse crossmember  30  and component holding means  31  is thus again ensured. 
     The invention is not restricted to the exemplary embodiments described and depicted. It also comprises all configurations by persons skilled in the art within the scope of the applicable claim 1. It is possible, for example, to change the horizontal transport movement into an oblique or diagonal movement. For this purpose, the gear  45  that is permanently connected to the carriage  23  is driven via a further gear with drive in such a way that a vertical movement is superimposed on the horizontal movement. 
     
       
         
           
               
               
             
               
                   
               
             
            
               
                 1 
                 Press line 
               
               
                 2 
                 Press 
               
               
                 3 
                 Press 
               
               
                 4 
                 Press ram 
               
               
                 5 
                 Press ram 
               
               
                 6 
                 Upper tool 
               
               
                 7 
                 Upper tool 
               
               
                 8 
                 Lower tool 
               
               
                 9 
                 Lower tool 
               
               
                 10 
                 Sliding table 
               
               
                 11 
                 Sliding table 
               
               
                 12 
                 Orientation station 
               
               
                 13 
                 Orientation station 
               
               
                 14 
                 Press upright 
               
               
                 15 
                 Press upright 
               
               
                 16 
                 Press upright 
               
               
                 17 
                 Press upright 
               
               
                 18 
                 Articulated-arm transport system 
               
               
                 19 
                 Articulated-arm transport system 
               
               
                 20 
                 Articulated-arm transport system 
               
               
                 21 
                 Articulated-arm transport system 
               
               
                 22 
                 Vertical guide rails 
               
               
                 23 
                 Carriage 
               
               
                 24 
                 Guides 
               
               
                 25 
                 Drive motor 
               
               
                 26 
                 Lifting motor 
               
               
                 27 
                 Gear 
               
               
                 28 
                 Rack 
               
               
                 29 
                 Transport direction 
               
               
                 30 
                 Transverse crossmember 
               
               
                 31 
                 Component holding means 
               
               
                 32 
                 Panel 
               
               
                 33 
                 Panel stack 
               
               
                 34 
                 Component 
               
               
                 35 
                 Component 
               
               
                 36 
                 Component 
               
               
                 37 
                 Component transport travel curve 
               
               
                 38 
                 Parking position travel curve 
               
               
                 39 
                 Large-component transfer press 
               
               
                 40 
                 Pivot drive 
               
               
                 41 
                 Gear 
               
               
                 42 
                 Gear 
               
               
                 43 
                 First pivoting-arm part 
               
               
                 44 
                 Second pivoting-arm part 
               
               
                 45 
                 Gear 
               
               
                 46 
                 Gear 
               
               
                 47 
                 Gear 
               
               
                 48 
                 Pivoting angle 
               
               
                 49 
                 Gear 
               
               
                 50 
                 Intermediate gear 
               
               
                 51 
                 Gear 
               
               
                 52 
                 Shaft 
               
               
                 53 
                 Gear 
               
               
                 54 
                 Gear 
               
               
                 55 
                 Gear 
               
               
                 56 
                 Gear 
               
               
                 57 
                 Gear 
               
               
                 58 
                 Hollow shaft 
               
               
                 59 
                 Toothed belt pulley 
               
               
                 60 
                 Toothed belt 
               
               
                 61 
                 Toothed belt pulley 
               
               
                 62 
                 Pivot axis 
               
               
                 63 
                 Cardan joint 
               
               
                 64 
                 Changing device 
               
               
                 65 
                 Mounting 
               
               
                 66 
                 Toothed belt pulley 
               
               
                 67 
                 Toothed belt 
               
               
                 68 
                 Toothed belt pulley 
               
               
                 69 
                 Axis of rotation 
               
               
                 70 
                 Axis of rotation