Patent Publication Number: US-7718023-B2

Title: Vibration welding apparatus and welding method

Description:
INCORPORATED-BY-REFERENCE TO RELATED APPLICATIONS 
     This application is a divisional application of U.S. Ser. No. 11/440,066, filed May 25, 2006, now U.S. Pat. No. 7,637,300, the entire contents of which is incorporated by reference. 
    
    
     TECHNICAL FIELD 
     The present invention relates to the field of vibration welding technology based on frictional heating, a result of applying a relative vibration (motion) to a plurality of work pieces made of thermoplastic material. 
     BACKGROUND ART 
     In the embodiment of the invention of Japanese Unexamined Patent Publication No. 9-85833 (Patent Document 1), there is disclosed a technology for executing a vibration welding process by bringing two work pieces made of a thermoplastic material into contact with each other in a face to face manner. 
     In the embodiment of the invention of Japanese Unexamined Patent Publication No. 9-151723 (Patent Document 2), there is disclosed a technology for executing vibration welding of two work pieces brought into contact with each other by a fixed side tool and a vibration side tool. 
     DISCLOSURE OF THE INVENTION 
     Problem to be Solved by the Invention 
     It is impossible to weld three or more work pieces to each other in a sandwich shape in a single weld, by the technologies disclosed in the documents 1 and 2 mentioned above. 
     The problem to be solved by the present invention exists as it is hard to develop a technology for integrally welding three or more work pieces in accordance with sequential working steps. 
     Further, the following problems typically occur while manufacturing this conventional thermoplastic product. 
     For example, a center console box (a storage box) arranged between a driver&#39;s seat and an assistant driver&#39;s seat in a motor vehicle is formed in a complicated shape, and a metal mold having a complicated shape is necessary for integrally molding it in a single piece, so that there is a risk that a molding defect of a finished product results. 
     Further, in a means for coupling a plurality of work pieces by screws or fasteners, not only is there a risk that the screw loosens due to vibrations, but also a manufacturing cost is increased. In addition, there is a risk of reduced strength or structural integrity. 
     With respect to the various problems mentioned above, the problem to be solved by the present invention is as follows. 
     A first object of the present invention is to provide a structure in which three or more work pieces made of thermoplastic material can be joined by vibration welding into an integral sandwich shape. 
     A second object of the present invention is to provide a structure in which three or more work pieces made of a thermoplastic material can be joined by vibration welding into a single assembly with superior strength. 
     A third object of the present invention is to provide a structure in which a finished product made of a thermoplastic material and having a complicated shape can be manufactured with high quality without causing manufacturing imperfections. 
     A fourth object of the present invention is to provide a structure in which the quality of a welded product can be improved by controlling relative motion and a range of fit into the lower tool receiving block so as to minimize variations in final height by a slide stabilizing means. 
     A fifth object of the present invention is to provide a structure in which quality of a welded product can be improved by controlling (adjusting) an elevation position of the lower tool block. 
     A sixth object of the present invention is to provide a structure in which a complicated and expensive metal mold is not required. 
     A seventh object of the present invention is to provide a structure in which a manufacturing labor can be reduced and waste can be effectively recycled without sorting at the time of disposal, because the work pieces can be integrally joined without fixing means made of a different material such as a metal screws or the like. 
     An eighth object of the present invention is to provide a structure for which manufacturing time can significantly reduced, because vibration welding of the work pieces can be executed in accordance with sequential manufacturing steps. 
     Means for Solving the Problems 
     The means for achieving the objects mentioned above are as follows. 
     (1) A vibration welding apparatus for accomplishing the vibration welding of three or more work pieces, made of a thermoplastic material, to make them integral, in a sandwich shape, comprising: 
     an upper tool means supporting a first work piece so as to apply a lateral vibratory motion to it by a vibration means; and 
     a lower tool means capable of supporting a plurality of second work pieces to be welded to at least both surfaces of the first work piece, 
     wherein the vibration welding apparatus is provided with a means capable of actuating the lower tool means in such a manner as to move the second work pieces in a height direction by an elevating means so as to align with the first work piece, and move the second work pieces toward the first work piece in a lateral direction by a slide actuating means so as to bring them into contact with the first work piece. 
     (2) A vibration welding apparatus as recited in the item (1) mentioned above, wherein the vibration welding apparatus is provided with a slide stabilizing means capable of synchronizing a relative movement in a lateral direction of right and left lower tool blocks. 
     (3) A vibration welding apparatus as recited in the item (1) mentioned above, wherein the vibration welding apparatus is provided with a slide stabilizing means capable of stabilizing a relative movement in a lateral direction of right and left lower tool blocks in a height direction. 
     (4) A vibration welding apparatus as recited in the item (1) mentioned above, wherein the vibration welding apparatus is provided with a distance sensor capable of controlling an interval between right and left lower tool blocks. 
     (5) A vibration welding apparatus as recited in the item (1) mentioned above, wherein the vibration welding apparatus is provided with an elevation control lever regulating a height position of an elevation frame and a frame mechanical stop. 
     (6) A vibration welding method for executing vibration welding of three or more work pieces made of a thermoplastic material to make them integral in a sandwich shape, comprising the following sequential steps of: 
     (A) a work piece installation step of installing a first work piece and at least a plurality of second work pieces to be welded to both side surfaces of the first work piece to an upper tool means and a plurality of lower tool means arranged apart from each other respectively; 
     (B) a work piece contact step of making a plurality of lower tool means ascend and moving them close to each other so as to pressure-contact the first work piece and the second work pieces; 
     (C) a vibration welding step of generating a frictional heating between the first work piece and the second work pieces pressure-contacted to the first work piece by applying a lateral motion so as to partly melt the work pieces, by the upper tool means; and 
     (D) a work piece cooling step of stopping the lateral motion so as to execute natural cooling. 
     Effects of the Invention 
     Special effects of the present invention are as follows. 
     1. It is possible to execute vibration welding of at least three work pieces made of the thermoplastic material to make them integral in a sandwich shape. 
     2. The strength of the finished product, obtained by the vibration welding, is superior. 
     3. It is possible to obtain a finished product, having a high quality, without requiring a metal mold having a complicated shape. 
     4. Since the finished product does not include different materials such as a metal fastener, or the like, it is possible to dispose (recycle) without necessity of sorting for waste collection. 
     5. Since the manufacturing steps (sequence) can be reduced, productivity is improved. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a side sectional view of a best mode in accordance with the present invention; 
         FIG. 2  is a functional block diagram of  FIG. 1 ; 
         FIG. 3  is a view of a preceding step; 
         FIG. 4  is a view of a work setting step; 
         FIG. 5  is a view of a lower tool means ascending step; 
         FIG. 6  is a view of a work pressure-contact step; 
         FIG. 7  is a view of the vibration welding step; 
         FIG. 8  is a view of a drop prevention means retracing step; 
         FIG. 9  is a view of a center box releasing step; 
         FIG. 10  is a view of a right and left panels releasing step; 
         FIG. 11  is a view of a center console unloading step; and 
         FIG. 12  is a perspective view of parts of the center console. 
     
    
    
     PREFERRED EMBODIMENT OF THE INVENTION 
     A description will be given below of a best mode of the present invention with reference to  FIGS. 1 to 11 . 
     A vibration welding apparatus  1000  shown in  FIG. 1  corresponds to a specific example forming a center partition cum storage device (a center console) arranged between a drive&#39;s seat and a assistant driver&#39;s seat in a motor vehicle, and has the following structure. 
     1. Summary of Vibration Welding Apparatus  1000   
     Various means mentioned below are arranged in a frame means  100  constituted by a fixed frame  110  and an elevation frame  120 . 
     In particular, in the elevation frame  120  ascended and descended by a hydraulic actuation means  200 , there is mounted a lower tool means  500  which is moved by a slide actuation means  300  and can hold a first work piece (a center box) by an adsorption means  400 , and in the fixed frame  110 , there is suspended an upper tool means  700  to which a lateral motion is applied by a vibration generating means  600  and which can hold a second work piece (right and left panels) by the adsorption means  400 , wherein motions thereof are controlled by a control means  800  mentioned below. 
     2. Structure of each of Individual Means 
     (1) Upper Tool Means  700   
     For executing vibration welding of a center box CB and left and right panels LP and RP constituting a center console CC as shown in  FIG. 12 , the upper tool means  700  holding the center box CB is provided with two upper tool receiving blocks  720  in a suspending manner under a lower surface of an upper tool plate  710  connected to the fixed frame  110 , as shown in  FIG. 1  so as to form a pair, an outer side of a lower portion thereof is lined with a first cushioning material  721  to be brought into contact with the center box CB, and the center box CB can be held by a box vacuum cup  410  of the adsorption means  400  being inserted into the center box CB. 
     Further, the structure is made such that a lateral motion is applied to the upper tool plate  710  from a vibration generation means (a vibrator)  600 . 
     (2) Lower Tool Means  500   
     Left and right lower tool receiving blocks  510  and  520  arranged in a face to face manner in the lower tool means  500  are mounted on the elevation frame  120  so as to freely reciprocate in a lateral direction, are linearly moved close to each other and apart from each other by a slide actuation means  300  mentioned below, are provided with second and third cushioning pieces  511  and  521  on facing surfaces to support the left and right panels LP and RP constituting the center console CC, and can hold the left and right panels LP and RP in a face to face manner by left and right panel vacuum cups  420  and  430  of the adsorption means  400 . 
     The slide actuation means  300  mentioned above is structured such that outer ends of piston rods  311  and  321  of first and second air cylinders  310  and  320  arranged on the elevation frame  120  are respectively coupled to left and right flanges  513  and  523  provided on base frames  512  and  522  of the left and right lower tool blocks  510  and  520  so as to protrude uprightly. 
     Further, the respective base frames  512  and  522  are continuously provided with a pair of racks  514  and  524  worked with a pinion  530 , and are interposed with a slide stabilizing means  560  in which the sliders  515  and  525  protruded under the lower surfaces of the base frames  512  and  522  are engaged with rails  123  on the elevation frame  120 . 
     A distance sensor  900  detecting an interval between the left and right lower tool receiving blocks  510  and  520  which are moved close to each other and apart from each other in accordance with the welding work, for example, such a sensor detecting a change of the distance on the basis of a change of an eddy current flowing through a metal surface, is provided between the left and right lower tool receiving blocks  510  and  520 . 
     A drop prevention means  920  of the center box CB is structured such that a holding plate  921  for preventing the center box CB held by the upper tool receiving block  710  from disengaging and dropping is fixed to an upper end of a piston lever  923  of a fluid cylinder  922 , and can stably hold the center box CB at a time of a welding process. 
     (3) Hydraulic Elevating Means  200   
     The elevation frame  120  is coupled to the piston lever  211  of the hydraulic cylinder  210 , is structured such as to make the lower tool means  500  ascend and descend at a time of the welding process, and is structured such that the elevation control lever  121  connected to the elevation frame  120  hits against the frame stopper  122  on the fixed frame  110 , thereby regulating a height position of the elevation frame  120  and improving a safety. 
     (4) Control Means  800   
     The control means  800  constituting a C.P.U is wired as shown in  FIG. 2 , and can precisely actuate and stop each of the means in correspondence to a command from an operation instruction portion  810 . 
     In particular, the hydraulic actuating means  200  is actuated by the control means  800 , thereby controlling the elevation frame  120  so as to ascend and descend, holding the center box CB to the upper tool receiving block  720  by the adsorption means  400  and holding the left and right panels LP and RP to the left and right lower tool receiving blocks  510  and  520 , respectively. 
     Further, the center box CB and the left and right panels LP and RP can be pressure-contacted by moving the left and right lower tool receiving blocks  510  and  520  by the slide actuation means  300 , and the vibration welding process can be executed by the vibration generation means  600 . The interval between the left and right lower tool receiving blocks  510  and  520  can be controlled by the distance sensor  900  for stabilizing the welding process, and the height of the elevation frame  120  can be safely controlled by the frame stopper  122 . 
     Further, the center box CB can be stably held by controlling the drop preventing means  920 . 
     3. Work Piece 
     Three work pieces constituting the center console shown in  FIG. 12  are all made of a thermoplastic material such as an ABS resin or a PP material. 
     The center box CB positioned in the center and exposed to the vibration welding process is formed in a box shape. 
     Welding ribs LIB inwardly protruding toward the center box CB are formed in a laterally parallel shape on the left and right panels LP and RP positioned in both sides of the center box CB and welded to the center box CB in a sandwich shape by the vibration welding. 
     4. Vibration Welding Method 
     A description will be given below of a welding method by the vibration welding apparatus  1000  mentioned above for each of the steps on the basis of  FIGS. 3 to 11 . 
     (1) Preceding Step 
     As shown in  FIG. 3 , the elevation frame  120  is at a descent position, the left and right lower tool receiving blocks  510  and  520  are arranged apart from each other, and the upper tool receiving block  720  is arranged apart from and above them, whereby a standby state is achieved. 
     (2) Work Setting Step 
     As shown in  FIG. 4 , the center box CB corresponding to the work piece is fitted to the upper tool receiving block  720 , the left and right panels LP and RP are inserted to the left and right tool receiving blocks  510  and  520 , and the adsorption means  400  is started, whereby the center box CB and the left and right panels LP and RP are respectively adsorbed to the upper tool receiving block  720  and the left and right lower tool receiving blocks  510  and  520  by the box vacuum cup  410  and the left and right panel vacuum cups  420  and  430  respectively so as to be stably held. 
     (3) Lower Tool Means  500  Ascending Step 
     As shown in  FIG. 5 , the hydraulic cylinder  210  is started, the lower tool means  500  is made to ascend together with the elevation frame  120 , and the left and right panels LP and RP are arrived at a position properly facing the center box CB. 
     With respect to the ascending amount of the elevation frame  120  at this time, the elevation frame  120  can safely ascend until the elevation control lever  121  is constrained to the stop position by the frame stopper  122 . 
     Further, the center box CB is supported from the lower surface and the drop can be previously prevented by ascending of the holding plate  921  coupled to the piston lever  923  of the hydraulic cylinder  922  of the drop prevention means  920 . 
     (4) Work Pressure-Contact Step 
     As shown in  FIG. 6 , the piston rods  311  and  321  of the first and second air cylinders  310  and  320  are actuated as shown by arrows, the left and right tool receiving blocks  510  and  520  are moved in a direction coming close to each other, and the center box CB is pinched in a sandwich shape by the left and right panels LP and RP, whereby the welding ribs LIB are set in a pressure-contact state. 
     At this time, since the slide stabilizing means  560  is interposed between each of the piston rods  311  and  321 , the left and right tool receiving blocks  510  and  520  are moved at a same distance, and are stably maintained by the rails  123  and the sliders  515  ad  525 . 
     (5) Vibration Welding Step 
     As shown in  FIG. 7 , a lateral motion in a direction orthogonal to the paper surface is applied to the upper tool receiving block  720  from a vibrator  600  coupled to the upper tool plate  710 , a frictional heating is generated between the welding ribs LIB of the left and right panels LP and RP and the center box CB, and leading ends of the welding ribs LIB are melted, whereby the left and right panels LP and RP and the center box CB are welded. 
     During the work, the first and second air cylinders  310  and  320  are additionally actuated while detecting the distance of a melted portion corresponding to a melt margin of the welding rib LIB by the distance sensor  900 , and the welding process is promoted by bringing the left and right lower tool receiving blocks  510  and  520  closer slightly (about 3 mm). 
     (6) Cooling Step 
     In a state of the step (5) mentioned above, the vibrator  600  is stopped by a control means on the basis of the signal of the distance sensor  900 , and the position is held for a short moment (about 3 seconds) to remain ready for cooling and hardening. 
     (7) Drop Prevention Means  920  Retracting Step 
     As shown by an arrow in  FIG. 8 , the holding plate  921  is made to descend so as to be isolated from the lower surface of the center box CB. 
     (8) Center Box CB Releasing Step 
     As shown in  FIG. 9 , the operation of the box vacuum cup  410  of the adsorption means  400  is stopped, and the elevation frame  120  is made to descend, whereby the upper tool receiving block  720  is released from the center box. 
     (9) Left and Right Panels LP and RP Releasing Step 
     As shown in  FIG. 10 , the operation of the left and right panel vacuum cups  420  and  430  of the adsorption means  400  is stopped, and the first and second air cylinders  310  and  320  are moved reverse in directions of arrows, whereby the left and right panels LP and RP are released from the left and right lower tool receiving blocks  510  and  520 . 
     (10) Center Console CC Unloading Step 
     As shown in  FIG. 11 , the center console CC formed by the steps mentioned above is unloaded from the vibration welding apparatus  1000 , and all the steps are finished. 
     Embodiment 
     An embodiment of the vibration welding work is as follows. 
     1. Lateral motion frequency l... 100 Hz to 240 Hz 
     2. Pressure applied to work piece ... about 50 to 1000 kg 
     3. Melt margin ... about 3 mm 
     4. Welding time ... about 3 sec 
     5. Cooling time ... about 3 sec 
     The work piece is as follows. 
     1. Raw Material 
     ABS resin, acrylic resin, polycarbonate, polyethylene, polypropylene. 
     2. Dimension 
     Thickness of center box ... about 2 to 5 mm 
     Thickness of left and right panels ... about 2 to 5 mm 
     INDUSTRIAL APPLICABILITY 
     In accordance with the present invention, it is possible to shorten a manufacturing process so as to obtain a finished product having a complicated shape and made of a thermoplastic material, it is possible to make the finished product as compact as possible, and the rigidity thereof can be increased. Accordingly, the present invention has an extremely great industrial applicability in view of applicability to various plastic products.