Abstract:
A device for automatically placing fastening bolts on support surfaces. The fastening bolts ( 1 ) have a disc plate ( 5 ) covered on their bottom side with a dry, hot-melt-type adhesive ( 6 ) receivable by heat application. The device consists of an elongated housing ( 3 ) having a bolt-catching device and a bolt feeding channel ( 37 ), which is connected to a flexible feeding tube ( 4 ) on an end projecting out of the housing. The adhesive bolts ( 1 ) with disc plate ( 5 ) are fed by air pressure into the housing ( 3 ) and through the bolt feeding channel ( 37 ) to the catching device ( 56, 57 ). There is a cylinder ( 11 ) with an induction coil ( 27 ) at the end of the bolt feeding channel ( 37 ). Upwardly from the inductor are means to press the adhesive bolts ( 1 ), which are inside the inductor ( 11 ), in the assembly position ( 29 ) on the supporting surfaces ( 2 ).

Description:
BACKGROUND OF THE INVENTION 
     The invention pertains to a device for automatic setting of retaining bolts on support surfaces, wherein the retaining bolts are provided with disk plates that are coated on their underside with a dry hot-melting adhesive that can be reactivated by the action of heat. 
     A device for setting such retaining bolts is known from DE 44 02 550 A1, in which the bolt shafts are seized by a pincer which can be brought into the intended bonding position by a robot arm. This publication does not discuss the manner in which bolts are supplied to the pincer, seized by it and set. 
     The present invention is directed to providing a device for automated setting of retaining bolts coated with hot-melting adhesive (adhesive bolts) of the aforementioned type. The adhesive bolts are brought in from a supply channel by means of compressed air and are glued to the support surfaces at the designated bonding points securely and permanently in the shortest possible time. 
     SUMMARY OF THE INVENTION 
     In order to solve this problem, a device is proposed according to the invention which is characterized by an elongated housing with a bolt-catching station and a bolt-supply channel. The bolt supply channel has an end projecting from the housing which is connected to a flexible supply hose, through which the adhesive bolts are conveyed. The bolts are conveyed disk-shoulder-first, into the housing by means of compressed air and through the bolt-supply channel up to the catching station. At the catching station a cylinder equipped with an induction coil (=inductor) is located at the end of the supply channel. Means for pressing the adhesive bolt present in the inductor onto the bonding position on the support surface are provided above the inductor. 
     The bolt-setting device guides the bolts disk-shoulder-first by means of a parts-separating device and a supply hose through the bolt-supply channel into the bolt-catching station. From there, the bolts are supplied to an inductor located underneath. After placing the bolts onto the bonding point the inductor induces the adhesive layer to melt by means of inductive heating and simultaneously presses the threaded bolt onto the bonding point, to produce a sufficiently firm adhesive bond with the support surface. 
     The bolt-catching station has the task of stopping the adhesive bolts brought in by means of compressed air as close to the bonding position as possible while preventing the impact of the disk plate provided with the adhesive layer against the support surface. 
     In a preferred embodiment of the bolt-setting device, a pincer of the type disclosed in DE 44 02 550 A1, seizes the bolt on its shaft and presses it onto the designated bonding position after the heating of the adhesive layer, and is employed as the means for pressing the adhesive bolt against the support surface. The bolt-catching station is located on a transfer plate seated to rotate freely underneath the bolt-supply channel and has a removal station offset by 180° from the catching station. The pincer is guided movably in the housing above the removal station in an axial extension of the inductor. The inductor is located underneath the removal station. 
     According to a refinement of the invention, the gluing process can be accelerated by pressing the bolt on the inductor at its lower edge onto the support surface simultaneously with the bolt disk while the latter is heated up by means of the inductor. 
     In order to relieve the bolt from transverse forces during the pressing, a cap is formed to be elastically deformable in the pressing direction between the gripping arms. The cap presses the bolt with uniform force against the support surface during the heating of the inductor after the opening of the gripping arms. 
     The gripping arms are moved by two coupled piston power cylinders: one piston power cylinder guiding the gripping arms up to the removal position in order to seize the bolt shaft, and the other moving the bolt into the bonding position at the lower edge of the inductor. 
     The intercalation of the clamp jaws in the two end positions of the rotating plate permits the bolts to be introduced into the uptake position with the plate and then held securely in the removal position without having to actuate the clamp jaws separately. The opening of the clamp jaws is accomplished solely by the introduction of the angled plunger tip which overcomes the force of the springs. 
     The inductor is to be understood as a cylindrical housing with an annular collar at the lower end, the inside diameter of which is somewhat larger than the outer diameter of the disk plate of the bolt. The inductor housing is seated on the housing underneath the removal position in an extension of the axis of displacement of the gripping arms. The housing wall of the inductor includes one or more coil windings which generate a magnetic field when current flows. Thus, both the bolt present in the inductor and the support surface are rapidly heated up. The adhesive material on the underside of the bolt disk is melted by the action of the heat, causing the bolt disk to be glued to the support surface. 
     In an alternative preferred embodiment of the bolt-setting device, a pressing plunger is movably guided in the housing in the axial extension of the inductor. The plunger is actuated by a power piston cylinder and is utilized as the means for pressing the adhesive bolts. The bolt-supply channel enters into the elongate axis of the inductor from one side of the housing underneath the upper position of the pressing plunger. 
     The pressing plunger is connected via a plunger rod to a pneumatically acting pressing cylinder which is in turn driven by a pneumatically acting advance cylinder which moves the pressing plunger from the initial position into the bonding position. Acting on the pressing plunger with two cylinders offers the advantage that the main motion of the plunger is accomplished by the advance cylinder, while the pressing cylinder is provided with a considerably shorter stroke, which is necessary to press against the adhesive bolt while the adhesive layer melts. 
     A slide gate is provided above the inductor transverse to the axis of the channel. The slide gate is equipped with a damping plate on the bolt supply side, to be utilized as a bolt-catching station. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Two embodiments of the invention, which will be described in further detail below, are presented in the drawings. Shown are: 
     FIG. 1 is a side view of the housing of the bolt-setting device according to the invention; 
     FIG. 2 is a longitudinal section through the housing along line II—II in FIG. 1; 
     FIG. 3 is a plan view of the housing of the bolt-setting device; 
     FIG. 4 is a section taken through the transfer plate along line IV—IV in FIG. 1; 
     FIG. 5 is a side view of a threaded bolt shown in position for setting; 
     FIG. 6 is a longitudinal sectional view taken through the housing along line VI—VI in FIG. 3 with pincer in the initial position; 
     FIG. 7 is the same longitudinal sectional view as FIG. 6 with pincer lowered to the removal position; 
     FIG. 8 is the same longitudinal sectional view as FIG. 6, with the pincer in bolt-setting or bonding position; 
     FIG. 9 is a side view of the housing of an alternative embodiment of the bolt-setting device with partial view of the slide arrangement; 
     FIG. 10 is a longitudinal sectional view taken through the housing along line X—X in FIG. 9; 
     FIG. 11 is a partial cross sectional view taken through the housing along line XI—XI in FIG. 9 with plan view of the slide gate; 
     FIG. 12 is a cross sectional view of the bolt-supply channel with the slide gate taken along line XII—XII in FIG. 11; 
     FIG. 13 is a longitudinal sectional view taken through the housing of the bolt-setting device with plunger in initial position; 
     FIG. 14 is the same longitudinal sectional view taken through the housing with plunger in bonding position, and 
     FIG. 15 is an enlarged sectional view of the lower setting area in the bonding position. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The bolt-setting device illustrated in the figures consists in each of the two embodiments of an elongated housing  3  with a bolt-catching device, as well as a bolt-supply channel  37 , which is connected at an end exiting the housing  3  to a flexible supply hose  4 . Via the hose  4 , adhesive bolts  1  with the disk plate  5 , FIG. 5, first are introduced by means of compressed air into the housing  3  and conveyed through the bolt-supply channel  37  up to a catching device and, from there, move into an inductor  11  located at one end of the supply channel  37 . The housing  3  can be connected by means of a connector part  31  to a robot arm, not shown. 
     The retaining bolts  1  consist, as is shown in FIG. 5 of a shaft  7  and an adjoining disk plate  5 , which is coated on its underside with a dry hot-melting adhesive  6  that can be activated by the action of heat. The shaft  7  is provided in the present embodiment with coarse threads  8  which are suited for fastening retaining elements with a receptacle hole suitably formed for threaded bolts. In place of threaded bolts, so-called head bolts or smooth bolts can be utilized if the associated fastening element has corresponding receptacles. The disk plate  5  can have any surface geometry which is suited to the conveyance by means of compressed air in the supply hose  4  or the supply channel  37 . 
     The most important components of the bolt-setting device as shown in FIGS. 1-4 are a bolt-setting plate  9 , pincer  10  and an inductor  11 , all of which are integrated into the housing  3  and are described subsequently in greater detail with respect to form and function: 
     As shown in FIGS. 2 and 4, the transfer plate  9  is seated to rotate underneath the bolt-supply channel  37  on the housing bottom  12  the transfer plate has a catching station  13  for the successively supplied bolts  1  and, offset from this by 180°, a removal station  14 . In the longitudinal wall  34  of the housing  3 , there is an opening  35  adapted to receive the transfer plate as it pivots in an arc (B), shown in dashed lines. 
     Two respective clamp jaws  15  which can be biased together by springs, for instance, leaf springs  16 , are seated in both stations of the transfer plate  9 . As is evident from FIG. 2, the clamp jaws  15  are provided with inclined insertion surfaces  17  which taper apart upwardly to the diameter of the bolt-supply channel  37 . The clamp jaws  15  are pressed apart by the disk plates  5  when the bolts slide over the insertion surfaces  17  and brought back into the initial position by the restoring forces of the leaf springs  16 . Thus, the bolt shaft  7  is firmly gripped by the clamp jaws  15  and simultaneously centered transfer plate  9  is rotated, as is shown in FIG. 6, by way of an articulated shaft  18  and a drive motor  19  consisting of a pneumatically operated pivot cylinder installed above in the housing  3 . 
     The pincer  10  is located above the removal station  14  and consists of two gripping arms  20  that are seated so as to be able to pivot on the lower end of a rectangular hollow profiled piece  21 . The rectangular hollow profiled piece  21  is bonded to the housing  24  of a short-stroke drive unit, which is in turn connected to a power piston cylinder  30  guided to move within the housing  3 . A plunger  22  acted on by the short-stroke drive unit and is guided to move in the hollow profiled piece  21  to engage its tip  23  between the extended ends of the gripping arms  20 . 
     The gripping arms  20  are held apart by spring force and can be pressed together by pressing the upper ends of the gripping arms  20  apart with the plunger tip  23 . A so-called cap  36 , located between the gripping arms  20 , is supported elastically in the displacement direction and is pressed against the bolt  1  when the gripping arms  20  are moved up to the bolt shaft  7 . 
     The power piston cylinder  30  is coupled by way of a transverse plate  32  to an additional power piston cylinder  33 , which is installed parallel to the displacement direction of the power piston cylinder  30  alongside it in the upper area of the housing  3 . This second power piston cylinder  33  is controlled separately from the first power piston cylinder  30  so that the latter can be moved downwards in a stroke H 1  by power piston cylinder  33  (FIG.  7 ). On the other hand, the pincer  10  is displaced by a stroke H 2  into a lower setting position  29  by the power piston cylinder  30  via the housing  24  of the short-stroke drive unit (FIG.  8 ). 
     The inductor  11  is positioned under the bottom  12  of the housing in an extension of the removal station  14  of the transfer plate  9  and consists of a cylindrical housing  26  that terminates at its lower end with an annular shoulder  25 . The inside diameter of the housing  26  is somewhat larger than the outside diameter of the disk plate  5 , so that the bolt  1  can be freely introduced by the pincer  10  into the opening of the inductor  11 . 
     The housing  26  has several induction coils which extend to the annular shoulder  25  and which are externally supplied with power via lines  28 . As soon as the pincer  10  has lowered the bolt  1  into the interior of the inductor  11 , the power is turned on via a sensor, not shown. Thereby a magnetic field is generated, which rapidly heats up the bolt  1  and thereby causes the adhesive layer  6  underneath the disk plate  5  to melt in a very short time. 
     The mode of operation of the above-described device is characterized by the following process steps. 
     First, a bolt  1  is fed from the supply channel  37  into the catching station  13  of the transfer plate  9 . The clamp jaws  15  are then pressed apart by the disk plate  5  of the bolt  1  and then spring back together again, so that the bolt shaft  7  is securely held by the clamp jaws  15  (FIG.  2 ). 
     Then the plate  9  is rotated by 180° through the opening  35 , and the bolt  1  is brought into the removal station  14 . The pincer  10  is now lowered by the stroke H 1  by the power piston cylinder  33  (FIG. 7) and the bolt shaft  7  is seized by the two gripping arms  20 , which are pressed together by the plunger  22 . After the robot arm has moved the setting device into the bonding position  29  (FIG.  8 ), the pincer  10  is moved by means of the second power piston cylinder  30  corresponding to the stroke H 2  downwards until the disk plate  5  of the bolt  1  is flush with the lower edge of the inductor  11 . Here, the annular shoulder of the inductor  11  contacts the support surface  2 . The gripping arms  20  are now opened slightly so that the bolt  1  is pressed by means of the elastically supported cap  23  onto the support surface  2 . 
     The induction current is then switched on and thus the magnetic field, which preferably has a frequency range of 10 kHz to 30 MHZ. The adhesive  6  on the bottom of the disk plate  7  is melted by the heat generated in this way so that the latter is bonded adhesively to the surface of the support surface  2 . 
     After a short span of time, the strength of the bonding necessary for further processing has been achieved. Then the bolt  1  is released by the gripping arms  20  and the setting device can be moved by the robot into the next bonding position  29 . 
     During the relatively fast-moving bonding action, the next bolt  1 , has already reached the receiving station  13  of the transfer plate  9  through the supply channel  37 . The transfer plate acts as a buffer and can be rotated into the receiving station  14  as soon as the pincer  10  has moved back into its initial position (FIG.  6 ). 
     An alternative embodiment of the bolt-setting device is illustrated in FIGS. 9-15 and, just like the previously described embodiment, can be mounted on the arm of a robot, not shown, or can be guided and placed by hand. The alternative embodiment differs from the above-described embodiment of FIGS. 1-4 essentially in two ways. First, the pressing of the adhesive bolt  1  in the bonding position  29  is accomplished by means of a pneumatically driven pressing plunger  38  and, second, the adhesive bolts  1  in the bolt-supply channel  37  are now caught up by a slide  56 . In the description of the modified embodiment below, the components that also occur in the same design or function in the first embodiment have the same reference numbers. 
     The bolt-setting device consists of a housing  3  with a bolt-supply channel  37 , which can be connected at an end projecting from the housing  3  to a flexible supply hose  4  for providing bolts  1 . An inductor  11 , which is formed from a cylindrical housing  26  that terminates at its lower end with an annular shoulder  25  is likewise placed at the end of the bolt-supply channel  37 . An induction coil  27  with two windings that are supplied with power via lines  28  from the outside is inlaid into it for rapid heating. 
     The pressing plunger  38  is connected via a plunger rod  39  to a pressing cylinder  40  and is movably guided by pneumatic force in an axial extension of the inductor  11 . The pressing cylinder  40  is in turn driven by a thruster  42  likewise under pneumatic force, which is mounted permanently in the housing  3 . The cylinder moves the pressing plunger  38  from the starting position (FIG. 13) into the bonding position (FIGS.  14  and  15 ). 
     The pressing cylinder  38  is connected via a yoke plate  43  to the piston  44  of the thruster  42  and is movably guided on both sides in corresponding grooves  46  of the housing  3  by means of sliding blocks  45 . The pressing cylinder  40  is positioned in the axis of motion of the thruster  42  between is yoke plate  43  and the flange  47  of a plunger rod guide  41  and is screwed to the flange  47 . Flange  47  and yoke plate  43  are additionally connected by four retainer sheets  48 . 
     The rod guide  41  is located outside the bolt-supply channel  37  in its upper starting position. The bolt supply channel enters the side of the housing  3  with an arched diverter  49  below the upper position of the pressing plunger  38  at an acute angle with respect to the extended axis of the inductor  11 . The diverter  49  is milled into the divided injection channel  50  such that the adhesive bolts  1  are conveyed effortlessly into the inductor  11 . 
     To displace the pressing plunger  38  into the bonding position  29 , a guide path  51  is bored for the plunger rod guide  41  in the injection channel  50  along an extension of the axis of the inductor  11 . As is particularly evident from FIG. 15, the pressing plunger  38  is screwed onto the plunger rod  39  and has the same outside diameter as the plunger rod guide  41 . The plunger  38  also has a funnel-shaped cutout  52  on its pressing side which is [intended] formed to press the adhesive bolt  1  onto the support surface  2  by way of the bolt shaft  7  and simultaneously to center the bolt  1  in the inductor  11  during the adhesive bonding procedure. 
     Located at the end of the bolt-supply channel  38  is an air-supply nozzle  53  which ends shortly above the contact surface of the annular shoulder  25 . In order to guarantee sufficient air flow through the air-supply nozzle  53  to build up a flow pressure behind the disk plate  5 , a concentric gap  54  exists between the nozzle  53  and the inductor  11 . The inductor housing  26  possesses several radially arranged boreholes  55  at the upper end of the gap  54 , to allow the air to vent laterally from the inductor  11  when the adhesive bolt  1  is resting on the support surface  2  during the bonding process. 
     As is evident from FIGS. 9 and 10, a slide gate  56  is provided on the bolt-supply side with a damping plate  57 . The slide gate  56  extends across the axis of the bolt-supply channel  37  the inductor  11 . This slide gate  56  is movably guided in a slide housing  58  which is screwed onto the outside of the closed injection channel  50 . 
     The slide gate  56  is connected at its rear end to a Bowden cable  60  which, as is shown in FIG. 9, is connected via an abutment  61  to an actuation cylinder  62 . The cylinder  62  is permanently installed in the upper portion of the housing  3 . The rearward end of the slide housing forms a slide stop  59 . 
     The slide gate  56  can be positioned as closely in front of the inductor  11  as space conditions in the housing  3  permit to catch the bolts. It is practical, however, to arrange the slide gate  56 , as drawn, in the bolt-supply channel  37  laterally alongside the guide path  51  of the pressing plunger  38 , specifically, as close before the diverter  49 . In this case, the slide gate  56  can be closed to catch the subsequent bolt  1  already after the advancement of the adhesive bolt  1  into the inductor  11 . The previous bolt  1  remains in the bonding position  29  and is pressed by the plunger  38  against the support surface  2 . In this way, the slide gate  56  can be utilized as a buffer, just like the transfer plate  9  of the initially described embodiment (see FIG.  15 ). 
     The bolt-setting device of the alternative embodiment illustrated in FIGS. 9-15 operates in the following manner: 
     The adhesive bolt  1  is injected through the supply hose  4  into the bolt-supply channel  37  with the slide gate  56  closed and decelerated and caught by the damping plate  57 . When the inductor  11  has reached its bonding position  29 , the slide gate  56  is opened by means of the actuation cylinder  62  by way of the Bowden cable  60 . The adhesive bolt  1 , driven by pneumatic power, moves through the diverter  49  into the inductor  1 . As soon as the bolt  1  lies on top of the support surface  2 , the thruster  42  and the pressing cylinder  40  are simultaneously subjected to pneumatic pressure, while the injection compressed air is briefly switched off. 
     The thruster  42  moves the plunger guide  41  at the same time into the bonding position, and the pressing cylinder  40  actuates the pressing plunger  38 , by way of the plunger rod  39 . This produces the necessary pressing force onto the adhesive bolt  1  for the adhesive bonding process after the actuation of the induction current. The displacement path of the pressing cylinder  40  is dimensioned such that the plunger  38  always remains in contact with the adhesive bolt  1  during the melting away of the adhesive layer  6 , despite the narrowing of the distance between the disk plate  5  and the support surface  2 . 
     After the desired adhesive strength of the adhesive bolt  1  has been achieved, the setting device can be retracted from the support surface  2  and brought into the next bonding position  29 .