Patent Publication Number: US-6219904-B1

Title: Automated device for maintaining wooden elements on a pressing table for assembling them

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to an automated device for maintaining wooden elements on a pressing table for assembling them. 
     The device is adapted for manufacturing different types of assemblies, such as frame elements, and particularly prefabricated trusses of restricted dimensions known as “gable trusses,” and widely used in traditional construction for supporting sloping roofs. 
     2. Description of Background and Relevant Information 
     The gable trusses are made by the triangular assembly, on a pressing table, of two principal rafters and a tie beam reinforced by judiciously arranged triangulation parts. The components of the gable trusses are arranged on the pressing table and are generally maintained by mobile abutments sliding in the metal plate grooves of the table and blocked by screws. “Connectors,” constituted of metal plates with claws, are then embedded at the junction points by means of mobile jacks borne by a gantry sliding longitudinally above the table. 
     Most often, the adjustment and setting of the gable trusses, as well as the control of the pressing by the jacks, is done manually. The logs are positioned on the table and maintained by abutments that are positioned manually. The connectors are then pre-embedded by means of a hammer, then the operator positions the jacks above the connectors and activates a lever that allows pressing by the descent of the jacks. The drawback is that, since the adjustment operations are manual, the time required is substantial, causing high labor costs, and the equipment used (mobile abutments, rails) is quickly damaged. 
     French patent No. 2 693 148, filed by Mr. DEBANNE and Mr. PORTALIER, discloses a device allowing the automatic positioning of the maintaining abutments in the metal plate grooves of the table due to a motoring unit operated by a computer assembly which also controls the movements of the mobile gantry and the pressing jacks. 
     This equipment has the drawback of requiring a table of a predetermined type, equipped with grooves machined into the plate, which raises its manufacturing costs. Furthermore, the longitudinal displacement of an abutment must be done in three steps, first of all, go to the end of the transverse groove in which it is initially located, then, pass along a longitudinal groove located along the edge of the table, then finally get into a new transverse groove. In cases of maladjustment, the deterioration risks incurred by the abutments, the grooves or the mandrill are substantial. 
     U.S. Pat. No. 2,707,546, filed on behalf of Mr. Christian DEBANNE, discloses a device allowing the use of any type of table authorizing unlimited displacements of the maintaining elements over the entire surface of the plate and minimizing the consequences of possible malfunctions of the mandrill or of the computer system. This device uses, for maintaining the parts to be assembled, saw logs constituted of cylindrical blocks equipped at the lower portion with tips that get embedded in a wooden plate covering the pressing table, these saw logs being positioned by means of a hollow mobile mandrill equipped on its inner surface with lugs that can slide into the “L”-shaped grooves provided at the periphery of the saw logs and arranged such that the saw logs can be released or made integral with the mandrill by making the latter rotate a fraction of a revolution in one direction or the other. 
     Not only do the combination of the rotational and translational movements run the risk of decreasing the reliability of the system, but the positioning of the mandrill above a saw log requires great precision which can only be obtained by substantially slowing down the horizontal movements of the mandrill. Above all, the displacement of a series of saw logs to achieve a new configuration requires numerous movements of the motoring unit and the gantry due to the fact that each saw log must be brought to its new location before the system can go back to find the next saw log. 
     SUMMARY OF THE INVENTION 
     The device according to the present invention overcomes these drawbacks. In addition to the use of any type of table, it allows the very quick displacement of a series of saw logs and has substantial reliability due to the elimination of the rotational movements of the system for grabbing the saw logs. 
     The invention provides for of a pressing table with a wooden plate and a mobile gantry comprising a magazine for storing saw logs utilizing vertical spindles mounted under a rail fixed laterally on the gantry and on which can be strung the saw logs which comprise a vertical bore with spring balls maintaining them due to grooves provided on the spindles, a motoring unit sliding along the rail, adapted for placing, removing and storing the saw logs, being equipped with a vertically mobile clamp comprising a lateral U-shaped opening capable of being inserted in ring-shaped grooves provided at the periphery of the saw logs. 
     The invention therefore provides for an automated device for maintaining wooden elements on a pressing table for assembling them, adapted to the manufacture of different types of assemblies, such as frame elements, particularly prefabricated trusses of restricted dimensions known as “gable trusses,” comprising a longitudinally mobile gantry bearing at least one pressing jack as well as a rail on which slides a motoring unit whose role is to position and displace the saw logs for maintaining the parts to be assembled. The movements of the mobile gantry, the motoring unit and the jack(s) are motor-driven and operated by a computer system. The maintaining saw logs comprise a vertical bore allowing them to be strung by the bottom onto vertical spindles arranged under the rail, and constituting a magazine for storing said saw logs. The motoring unit comprises a single or double rod, vertically mobile and equipped at its lower portion with a clamp, formed of a horizontal plate having a U-shaped lateral opening capable of being inserted in ring-shaped grooves provided at the periphery of the saw logs, each of these being equipped with an inner spring ball ensuring their immobilization on the spindles. 
     The invention also provides for a device characterized in that each of the spindles comprises a series of circular grooves distributed over their height and in which the spring balls of the saw logs can penetrate so as to immobilize the latter at a predetermined height. Each of the spindles may comprise a shoulder arranged at their base and arranged such that when the saw log located at the lowest point is removed, the saw logs located above descend by their own weight and are retained by the spring ball of the lower saw log pressing on said shoulder. When a saw log is inserted at the base of a spindle, the saw logs that are already present are pushed upwards. The spindles may be parallel with respect to one another and fixed along the length of the rail, at its lower portion. The spindles may be mounted on a rotating spring barrel, fixed under the rail and whose rotation allows bringing the spindle on which the selected saw log is located in front of the clamp. The U-shaped lateral opening of the clamp may comprise an elastic element, such as a spring ball, that is predetermined for maintaining a saw log in the clamp while allowing its insertion or its extraction by exerting a slight force. The motoring unit may be arranged such that the clamp can be positioned facing any saw log present on a spindle and be inserted in the ring-shaped groove, by using only the movements allowing the saw logs to be fixed on the plate, or allowing them to be removed, namely the horizontal movement of the unit along the length of the rail and the vertical movement of the clamp. The movements of the mobile gantry and the motoring unit may be operated by an electronic assembly, the data relative to the positions of the saw logs for a predetermined configuration being prepared on a standard computer, due to an ad hoc software, and sent by an appropriate device to the electronic system. The position of each saw log may be saved after each movement, so as to allow its retrieval and to ascertain the displacement to be made for a new, later configuration. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     On the attached drawings, given by way of non-limiting examples of embodiments of the present invention: 
     FIG. 1 shows a pressing table seen from the top, with a gable truss in place, 
     FIG. 2 shows the table seen from the end, along Arrow A of FIG. 1, 
     FIG. 3 is an enlargement of Detail B of FIG. 2, 
     FIG. 4 is an axonometric view on a different scale showing the clamp of the motoring unit in the vicinity of a spindle bearing the saw logs, 
     FIG. 5 shows in an axial cross-section a saw log and the lower end of a spindle, and 
     FIGS. 6 and 7 show in the same circumstance two spindle alternatives on which the saw logs are stored. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The device, FIGS. 1-7, is mounted on a pressing table  1  comprising a mobile gantry  2 , perpendicular to the table  1  and being displaced longitudinally above the latter. 
     The plate  3  of the pressing table  1  is wooden, without grooves, and can be, for example, a plate of solid wood, plywood or pressed wood covering the entire surface of a metal table. Saw logs  4  for maintaining the parts to be assembled can be fixed in position due to tips  5  arranged at their lower portion and get embedded in the wood of the plate  8 . 
     The mobile gantry  2  comprises one or several jacks  6 , at least one of which can be `propelled transversely to the longitudinal axis of the table  1 . The role of these jacks  6  is to exert a strong pressure from the top downward in the direction of the plate  3 . 
     After positioning the maintaining saw logs  4 , the component parts of the gable trusses  7  are arranged on the plate  3 , the connectors  8  are pre-embedded manually, then the mobile gantry  2  and a jack  6  are displaced successively above each connector  8  before activating the jack  6  for a final tightening. 
     The gantry  2  is laterally equipped with a rail  9  perpendicular to the axis of the pressing table  1 , on which slides a motoring unit  10  that can be positioned above any point of the plate  3 . This motoring unit comprises a single or double rod  11 , vertically mobile and ending at its lower portion by a clamp  12 , utilizing a horizontal plate having a predetermined lateral U-shaped opening so as to be inserted into the ring-shaped grooves  13  provided at the periphery of the saw logs  4 . This opening comprises an elastic element  14 , such as a spring ball, that is predetermined for maintaining a saw log  4  in the clamp  12  while allowing its insertion or its extraction by exerting a slight force. 
     Under the rail  9  are mounted several vertical spindles  15 , each comprising a series of circular grooves  16  distributed along its height. These spindles  15  constitute a magazine for storing the saw logs  4  which comprise a vertical bore allowing them to be strung from the bottom onto these spindles  15 , either manually or by utilizing the clamp  12 . Each saw log  4  is equipped with an inner spring ball  17  arranged to immobilize it at a predetermined height by penetrating into one of the grooves  16 . 
     The circular grooves  16  can be replaced by a shoulder  18  arranged at the base of the spindles  15 . When the saw log  4  located at the lowest point is removed, the saw logs located above descend by their own weight and are retained by the spring ball  17  of the lower saw log by pressing on the shoulder  18 . In the same manner, when a saw log  4  is inserted at the base of a spindle  15 , the saw logs that are already present are pushed upwardly. Thus, the clamp  12  movements are simplified, since the clamp  12  does not have to climb up along the spindles  15  to reach the saw logs  4  located at the top portion (FIG.  7 ). 
     The motoring unit  10  is arranged such that the clamp  12  can be positioned facing any saw log  4  present on a spindle  15  and be inserted in the ring-shaped groove  13 , by using only the horizontal movement of the unit along the length of the rail  9  and the vertical movement of the clamp  31 . 
     These same movements allow fixing the saw logs  4  on the plate  3  at predetermined locations, or removing them to store them on the vertical spindles  15 . No rotational or longitudinal movement of the clamp  12  is necessary. 
     These spindles  15  can, for example, be parallel with respect to one another and fixed along the length of the rail  9  at its lower portion (FIG.  3 ). In this case, the clamp  12  will go around the bottom of the spindles  15  located in front of the spindle  15  on which the saw log  4  to be reached is located and will climb the length thereof up to the adequate height. 
     In an alternative embodiment, the spindles  15  are mounted on a rotating spring barrel, fixed under the rail  9  and whose rotation will allow bringing the spindle on which the selected saw log  4  is located in front of the clamp  12 . 
     This arrangement makes it possible to substantially reduce the amplitude of the translational movements of the gantry  2  so as to modify a configuration of the saw logs  4 , which considerably decreases the length of the operations and, consequently, the manufacturing costs. Indeed, during a configuration modification, all of the saw logs  4  from a zone are removed and arranged on the spindles  15  before bringing the gantry  2  over another zone. The same procedure is implemented for positioning the saw logs  4 . 
     The movements of the mobile gantry  2 , the motoring unit  10  and the jacks  6  are operated by an electronic assembly that can, for example, be installed in a box mounted on this gantry  2 . The data relative to the positions of the saw logs  4  and the connectors  8  for a predetermined series of identical gable trusses  7  are prepared on a standard computer, due to an ad hoc software, and sent by an appropriate device, such as a cable or a diskette, to the electronic assembly. The position of each maintaining saw log  4  is saved after each movement, allowing it to be retrieved and to ascertain the displacement to be made for a new, later configuration. 
     The positioning of the various component elements maximizes the useful effects of the invention which have not been obtained by similar devices today.