Patent Publication Number: US-2023158756-A1

Title: Welding machine for synthetic resins

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims priority to and the benefit of Korean Patent Application No. 10-2021-0163008 filed on Nov. 24, 2021, the disclosure of which is incorporated herein by reference in its entirety. 
     TECHNICAL FIELD 
     The present invention relates to a welding machine used to join synthetic resins, and more particularly, to a welding machine for synthetic resins which performs ultrasonic welding, and discharges hot air to a gap between synthetic resin fabrics so as to facilitate rapid and precise welding between the synthetic resin fabrics through preheating of the fabrics. 
     BACKGROUND ART 
     Recently, as many people actively engage in leisure activities and hobbies, various functional clothes, costumes, shades, tents, etc. are widely being used. 
     In general, these various types of articles including clothes should basically have a waterproof function, and are manufactured using waterproof fabrics. 
     These articles, such as functional clothes, costumes, shades, tents, etc., requiring the waterproof function are manufactured using the waterproof fabrics, and may thus prepare for rainy weather through the waterproof function while faithfully performing the original functions thereof. 
     Therefore, the waterproof fabrics are joined by welding so as to secure water proofness, and heat welding is mainly used as a joining method. 
     As heat welding methods, hot air welding, ultrasonic welding, high frequency welding, spin welding, vibration welding, etc. are applied. 
     There among, hot air welding is mainly used to bond a waterproof tape to the sewn part of a fabric, the waterproof tape is melted by applying hot air of a high temperature thereto, and simultaneously, the waterproof tape is bonded to the sewn part of the fabric by allowing the waterproof tape and the fabric to pass through a gap between an upper roller and a lower roller, which are formed of a rubber. 
     However, hot air welding, in which the high-temperature hot air is discharged to a relatively large area, may be used to bond the waterproof tape having a relatively small thickness to the fabric by melting, but, in the case in which thick fabrics used in tents or the like overlap each other so as to be joined to each other, waterproof coating surfaces around the bonding surface between the fabrics are burned off and thus come off due to excessively hot air. 
     Particularly, conventional fabrics used in tents, etc. were coated with a waterproof material, i.e., general PE and PVC coating materials, but recently, in order to prevent environmental pollution, polymer coating using eco-friendly substances is applied, and, in case of hot air welding, when weak hot air is applied, the decomposition of a polymer is poor and thus joining is not properly achieved, and, when excessively hot air is applied, the coating surfaces are burned off. 
     In order to solve the above problems, an ultrasonic welding method in which, when ultrasonic vibration energy is transmitted to work pieces to be welded through an ultrasonic horn, frictional heat is momentarily generated on the between the ultrasonic horn and an upper welding wheel and is thus applied to the bonding surface between the work pieces, and thus, a synthetic resin is melted so that joining between the work pieces is achieved by strong molecular bonding, is applied. 
     However, in case of the above-described ultrasonic welding method, a sufficient time needs to be taken to provide frictional heat to fabrics, and thus, welding time delay causes reduction in workability. 
     Further, in the general ultrasonic welding method, since the ultrasonic horn is fixed or horizontally rotated in the state in which the front end surface of the ultrasonic horn is provided in a planar form and the welding wheel is vertically rotated, it may be difficult for fabrics to stably enter a welding space or slip of the fabrics may occur during the entry process of the fabrics, and thereby, welding may not be smoothly performed. 
     PRIOR ART DOCUMENT 
     Patent Document 
     
         
         (Patent Document 1) Korean Patent Registration No. 10-1139578 
         (Patent Document 2) Korean Patent Registration No. 10-2088557 
       
    
     SUMMARY OF THE INVENTION 
     Problems to be Solved 
     Therefore, the present invention has been made in view of the above problems, and it is an object of the present invention to provide a welding machine for synthetic resins which performs welding of fabrics using ultrasonic waves and through preheating sufficient not to burn off a coating solution on the surfaces of the fabrics using hot air, so as to achieve rapid and firm welding due to concentrated molecular decomposition and melting on the bonding surface between the fabrics. 
     It is another object of the present invention to provide a welding machine for synthetic resins which allows both an ultrasonic horn and a welding wheel to be rotated vertically, so as to achieve rapid and stable entry of fabrics and stable welding while preventing the fabrics from slipping. 
     It is yet another object of the present invention to provide a welding machine for synthetic resins which may achieve stable welding of various fabrics through adjustment of pressing force of a welding wheel depending on the thickness or the material of the fabrics, etc. 
     In accordance with the present invention, the above and other objects can be accomplished by the provision of a welding machine for synthetic resins including a main body including a work table provided at a middle part of the main body so as to protrude toward one side and having a horn withdrawal hole formed there through, and a support arm provided at an upper part of the main body so as to protrude upwardly from the work table, an elevating support provided on the support arm and including a screw mount part configured to protrude from one side of an upper part of the elevating support, and an elevating cylinder configured such that a cylinder rod is provided therein so as to be withdrawn downwards from the elevating cylinder, an ultrasonic generator including a vibrator, a booster and an ultrasonic horn, provided under the work table, rotated vertically by driving a motor, and configured to generate ultrasonic vibration through a circumferential surface of the ultrasonic horn, a welding unit provided on the elevating support, elevated and lowered by operation of the elevating cylinder, and configured to press fabrics and to generate frictional heat in cooperation with the ultrasonic horn so as to join the fabrics, and a hot air generator provided on the elevating cylinder, and rotated leftwards and rightwards to provide hot air to the supplied fabrics, wherein the ultrasonic horn includes a body connected to the booster, and a disc-shaped head configured to protrude outwards from a front end of the body so as to radiate the vibration through a protruding circumference of the head, wherein the head includes a vibration guide plate connected to the front end of the body by a connection curve part having a designated curvature, provided in a disc shape having a greater diameter than a diameter of the body, and having front and rear curve parts having a designated curvature and formed at circumferences of front and rear surfaces of the vibration guide plate so as to expand a thickness of the vibration guide plate, and a vibration radiation part connected to the front and rear curve parts, and having a welding surface formed on an outer circumferential surface of the vibration radiation part. 
     The welding unit may include an elevating operation plate coupled to the elevating support so as to be slidable upwards and downwards, configured such that the cylinder rod is connected to the elevating operation plate, and having a latch provided on one side of the elevating operation plate, a welding wheel mounted at a lower end of the elevating operation plate by a roller support, rotated vertically in an opposite direction to the ultrasonic generator by driving a motor, and configured to weld the fabrics in cooperation with the ultrasonic horn, a pair of upper and lower fabric guides provided on the roller support and the work table so as to guide entry of the fabrics to be welded, respectively, and a stroke adjuster provided on the elevating support so as to adjust a lowering stroke distance of the elevating operation plate by locking the latch of the stroke adjuster. 
     The stoke adjuster may include a screw mounted vertically in a screw mount part of the elevating support so that a lower part of the screw is exposed, and having an adjuster handle provided on an upper end of the screw, a stopper screw-coupled to a lower part of the screw, having a spring provided on an upper part of the stopper and a scale measurement table provided at one side of the stopper, and configured such that the stopper ascends and descends using the elevating operation plate as a guide when the screw is rotated, and the latch is latched to an upper part of the stopper when the elevating operation plate is lowered, and a scale mounted on an upper part of the elevating support, and having a measurement rod provided to protrude downwards from the scale and configured to measure the lowering stroke distance of the elevating operation plate through interference with the scale measurement table. 
     The hot air generator may include a heater rod mount plate provided on an upper surface of the elevating support, a heater rod mounted on the heater rod mount plate by a rotating plate so as to be rotated leftwards and rightwards, and having a hot air discharge nozzle provided at a lower end of the heater rod and configured to discharge hot air to the supplied fabrics so as to preheat the fabrics, and a rotating cylinder mounted on the heater rod mount plate so as to be rotatable, and configured such that a cylinder rod is connected to the rotating plate so as to control rotation of the heater rod. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The above and other objects, features and other advantages of the present invention will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings, in which: 
         FIG.  1    is a perspective view of a welding machine for synthetic resins according to the present invention; 
         FIG.  2    is a front view of the welding machine for synthetic resins according to the present invention; 
         FIG.  3    is a perspective view showing a principal part of the welding machine for synthetic resins according to the present invention; 
         FIG.  4    is a perspective view showing a principal part of an ultrasonic generator of the welding machine for synthetic resins according to the present invention; 
         FIG.  5    is a cross-sectional view showing a principal part of an ultrasonic horn of the welding machine for synthetic resins according to the present invention; 
         FIG.  6    is a perspective view showing a principal part of a welding unit of the welding machine for synthetic resins according to the present invention; 
         FIG.  7    is a side view showing a principle part of a stroke adjuster of the welding machine for synthetic resins according to the present invention; 
         FIG.  8    is a perspective view showing a principal part of a hot air generator of the welding machine for synthetic resins according to the present invention; 
         FIG.  9    is a side view of the welding machine for synthetic resins according to the present invention in the state in which the stroke thereof is adjusted; 
         FIG.  10    is a side view of the welding machine for synthetic resins according to the present invention in the state in which the stroke thereof is adjusted; 
         FIG.  11    is a side view of the welding machine for synthetic resins according to the present invention in the state in which fabrics are welded; and 
         FIG.  12    is a side view of the welding machine for synthetic resins according to the present invention in the state in which ultrasonic vibration energy is applied to the fabrics. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Terms or words used in the following description and the claims are not interpreted as being limited to usual or dictionary meanings, and are interpreted as having meanings and concepts according with the technical scope of the present invention based on the principle that the inventor(s) can appropriately define the concept of a term so as to describe their own invention in the best mode. 
     Therefore, embodiments disclosed in the description and the drawings are merely exemplary and do not represent all of the technical scope of the present invention, and thus, it will be understood that there are various equivalents and modifications as substitutes of the embodiments at the time of filing of the present invention. 
     Hereinafter, the exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. 
       FIG.  1    is a perspective view of a welding machine for synthetic resins according to the present invention,  FIG.  2    is a front view of the welding machine for synthetic resins according to the present invention, and  FIG.  3    is a perspective view showing a principal part of the welding machine for synthetic resins according to the present invention. 
     As shown in  FIGS.  1  to  3   , a welding machine  1  for synthetic resins according to the preset invention includes a main body  100 , an elevating support  200 , an ultrasonic generator  300 , a welding unit  400 , and a hot air generator  500 . 
     First, the main body  100  forms the frame of the welding machine  1  for synthetic resins according to the present invention, and is provided vertically so that a control panel may be provided thereon. 
     Further, a plate-shaped work table  110 , which protrudes to one side, is provided at the middle part of the main body  100 , and a horn withdrawal hole  111  configured to induce an ultrasonic horn  330 , which will be described later, to be withdrawn upwards there through is formed through the work table  110 . 
     A support arm  120 , which horizontally extends above the work table  110 , is provided at the upper part of the main body  100 . 
     In addition, switches configured to operate the welding machine  1  for synthetic resins according to the present invention may be provided on the main body  100 . 
     The elevating support  200  of the welding machine  1  for synthetic resins according to the preset invention is configured such that the welding unit  400  and the hot air generator  500 , which will be described later, are installed and supported thereon. 
     In this regard, the elevating support  200  is provided at the end of the support arm  120  in the form of a block, such as a plate, and a screw mount part  210  protrudes from the upper part of one side of the elevating support  200 . 
     The elevating support  200  includes an elevating cylinder  220  configured to elevate and lower the welding unit  400 , which will be described later, and a cylinder rod  220   a  is provided in the elevating cylinder  220  so as to be withdrawn downwards from the elevating cylinder  220 . 
     The ultrasonic generator  300  of the welding machine  1  for synthetic resins according to the present invention is configured to generate ultrasonic waves so as to provide frictional heat. 
     For this purpose, referring to  FIG.  4   , the ultrasonic generator  300  is provided in a cylindrical structure in which a vibrator  310 , which is generally used, a booster  320  and the ultrasonic horn  330  are continuously disposed, and, in the present invention, the ultrasonic generator  300  is disposed horizontally under the lower surface of the work table  110 , and is configured to be rotated in the vertical direction. 
     In the present invention, the rotational force of the ultrasonic generator  300  may be generated by driving a motor  310 , without being limited thereto, and, for this purpose, the booster  320  is mounted on the lower surface of the work table  110  by a bearing (not shown) or the like, and the motor  301  is driven by a general belt pulley or the like. 
     Particularly, the ultrasonic horn  330  according to the present invention is configured to generate ultrasonic energy through the circumference thereof not through the front end surface thereof during a process of providing rotational force in the vertical direction through the above-described configuration of the ultrasonic generator  300  which is rotated vertically. 
     For this purpose, referring to  FIG.  5   , the ultrasonic horn  330  includes a body  340  which extends from the booster  320 . 
     Further, the ultrasonic horn  330  includes a head  350  which extends from the front end of the body  340  and substantially radiates ultrasonic vibration and, in this case, the ultrasonic horn  330  extending from the front end of the body  340  is provided in a disc shape having a designated thickness so as to protrude outwardly from the body  340  and thus to have a greater diameter than that of the body  340 . 
     In the present invention, the head  350  is configured to guide vibration transmitted from the body  340  to the circumference of the head  350 . 
     In this respect, the head  350  includes a vibration guide plate  351  configured to guide vibration transmitted from the body  340  to a vibration radiation part  355 , which will be described later, and the vibration guide plate  351  is provided at the front end of the body  340  so as to have a greater diameter than that of the body  340 . 
     Here, the body  340  extends from the rear surface of the vibration guide plate  351 , and a connection curve part  352  configured to smoothly transmit ultrasonic energy is formed at the position of the vibration guide plate  351  to which the body  340  is connected. 
     Front and rear curve parts  353   a  and  353   b , which are curved to have a designated curvature so as to smoothly transmit ultrasonic energy and to expand the thickness of the vibration guide plate  351 , are formed at the circumferences of the front and rear surfaces of the vibration guide plate  351 . 
     Further, the head  350  includes the vibration radiation part  355  configured to receive vibration transmitted from the vibration guide plate  351  and to substantially radiate the vibration so as to apply frictional heat, and the vibration radiation part  355  includes a welding surface  356 , which is formed in a circular band shape having a thickness corresponding to the distance between the edges of the front and rear curve parts  353   a  and  353   b , which is greater than the thickness of the vibration guide plate  351 , and a designated width, and generates frictional heat through the outer circumferential surface of the welding surface  356 . 
     That is, the ultrasonic generator  300  is configured to generate ultrasonic energy so as to generate frictional heat during a process of welding two fabrics. 
     The welding unit  400  of the welding machine  1  for synthetic resins according to the present invention presses the fabrics and welds the fabrics using frictional heat in cooperation with the ultrasonic horn  330 . 
     In this regard, referring to  FIG.  6   , the welding unit  400  includes an elevating operation plate  410 , the elevating operation plate  410  is coupled to the elevating support  200  by a general LM guide so as to be slidable upwards and downwards, and the cylinder rod  220   a  of the elevating cylinder  220  is coupled to the elevating operation plate  410  so that the elevating operation plate  410  is moved upwards and downwards using the elevating support  200  as a guide by operation of the elevating cylinder  220 . 
     A latch  411  is provided on the outer surface of the elevating operation plate  410 , and the latch  411  is configured to limit the downward movement of the elevating operation plate  410  in response to a stroke adjuster  440 , which will be described later. 
     Further, the welding unit  400  includes a welding wheel  420 , and the welding wheel  420  is provided as a metal roller having a designated thickness so as to correspond to the ultrasonic horn  330 . 
     Here, the welding wheel  420  is mounted on a roller support  421  through a shaft, the roller support  421  is coupled to the lower end of the elevating operation plate  410  so as to be moved upwards and downwards together with the elevating operation plate  410 , and the welding wheel  420  presses the fabrics between the welding wheel  420  and the ultrasonic wheel  330  when the roller support  421  is moved downwards. 
     In the present invention, the welding wheel  420  is rotated in the vertical direction, and concretely, is rotated in the opposite direction to the ultrasonic horn  330  so as to discharge the fabrics, supplied from the front, rearwards simultaneously with welding of the fabrics. 
     Here, the welding wheel  420  according to the present invention has rotational force through a rotation structure in which a motor  401  is directly connected to the welding wheel  420  or is connected to the welding wheel  420  through a separate belt pulley or chain sprocket. 
     Further, the welding unit  400  includes upper and lower fabric guides  430  and  430 ′ configured to guide supply of two fabrics to be welded. 
     Here, the upper and lower fabric guides  430  and  430 ′ are provided as C-shaped brackets which are opened in opposite directions, the upper fabric guide  430  is provided in front of the roller support  421 , and the lower fabric guide  430 ′ is provided on the work table  110 , thereby supplying the two fabrics to be welded to upper and lower regions so as to stably overlap each other. 
     Further, the welding unit  400  includes the stroke adjuster  440  configured to adjust the lowering stroke distance of the elevating operation plate  410 , which is moved upwards and downwards, so as to adjust fabric pressing force of the welding wheel  420 . 
     In this regard, as shown in  FIG.  7   , the stroke adjuster  440  includes a screw  441  having a screw thread formed on the lower part thereof, the screw  441  is vertically mounted in the screw mount part  210  of the elevating support  200  through a shaft so that the lower part of the screw  441  is exposed, and an adjuster handle  441   a  is provided on the upper end of the screw  441  so as to be rotatable. 
     Further, the stroke adjuster  440  includes a stopper  442  screw-coupled to the lower part of the screw  441 , having a spring  443  provided between the upper part of the stopper  442  and the screw mount part  210  so as to surround the screw  441 , and configured to ascend and descend along the screw  441  when the screw  441  is rotated, and the latch  411  of the elevating operation plate  410  is latched to the upper part of the stopper  442 . 
     Here, the stopper  442  is connected to the elevating support  200  by guide recesses and protrusions (not shown), and thereby, ascent and descent of the stopper  442  is guided by the elevating support  200 . 
     A scale measurement table  444  configured to come into contact with a measurement rod  446  of a scale  445 , which will be described later, is provided at one side of the stopper  442 . 
     Further, the stroke adjuster  440  includes the scale  445  configured to interfere with the scale measurement table  444  so as to measure the lowering stroke distance of the elevating operation plate  410 . 
     Here, the scale  445  may have any structure configured to eject the measurement rod  446  so as to measure a distance and, in the present invention, the scale  445  is vertically mounted on the elevating support  200  such that the measurement rod  446  comes into contact with the scale measurement table  444 . 
     Accordingly, the scale  445  is configured such that the measurement rod  446  responds to the scale measurement table  444 , and may thus measure the lowering stroke distance of the elevating operation table  410  when the elevating operation plate  410  is lowered and the latch  411  is latched to the stopper  442 , starting from a zero point, i.e., a position at which the elevating operation plate  410  is elevated by inserting the cylinder rod  220   a  into the elevating cylinder  220 , and may output the measured stroke distance through the control panel (not shown), which may display data, provided on the main body  100 . 
     That is, the welding wheel  420  of the welding unit  400  and the ultrasonic horn  330  in cooperation with each other may generate frictional heat, may press and weld the fabrics entering the gap between the ultrasonic horn  330  and the welding wheel  420 , and particularly, may accurately adjust the pressing force applied to the fabrics depending on the thickness or the kind of the fabrics, thereby being capable of facilitating stable welding of the fabrics. 
     The hot air generator  500  of the welding machine  1  for synthetic resins according to the present invention applies hot air to the supplied fabrics, and thus preheats the fabrics, prior to ultrasonic welding of the fabrics. 
     In this regard, as shown in  FIG.  8   , the hot air generator  500  includes a heater rod mount plate  510  provided on one side of the upper surface of the elevating support  200 . 
     Further, the hot air generator  500  includes a heater rod  520  axially coupled to the heater rod mount plate  510  by a rotating plate  522  provided at the upper part of the heater rod  520  so as to be rotatable leftwards and rightwards. 
     A hot air discharge nozzle  521  is provided at the lower end of the heater rod  520 , and the hot air discharge nozzle  521  discharges hot air generated by the heater rod  520  to the fabrics supplied below the hot air discharge nozzle  521 . 
     In the present invention, the heater rod  520 , which is generally applied to conventional hot air welders, may be used, and may have any structure which may generate and discharge hot air. 
     Further, the hot air generator  500  includes a rotating cylinder  530  mounted on the heater rod mount plate  510  so as to be rotatable, and a cylinder rod  530   a  is connected to the rotating plate  52  so as to rotate the heater rod  520  leftwards and rightwards through insertion and withdrawal of the cylinder rod  530   a  into and from the rotating cylinder  530 . 
     That is, the hot air generator  500  is configured such that, when the lower end of the heater rod  520  is rotated, and concretely, rotated to the left in the figure, the hot air discharge nozzle  521  is located between the upper and lower fabric guides  430  and  430 ′ and discharges hot air to the upper and lower fabrics. 
     Hereinafter, operation of the welding machine  1  for synthetic resins according to the present invention having the above-described configuration will be described in detail with reference to the accompanying drawings. 
     As shown in  FIGS.  1  to  8   , the welding machine  1  for synthetic resins according to the present invention may stably and rapidly weld fabrics having a comparatively large thickness or fabrics coated with a polymer without damaging the coating surfaces of the fabrics through preheating of the fabrics and ultrasonic welding, may achieve smooth supply and discharge of the fabrics, and particularly, may implement stable welding of the fabrics by providing stable pressing force to the fabrics depending on the thickness and kind of the fabrics. 
     First, the welding machine  1  for synthetic resins according to the present invention adjusts the lowering stroke distance of the welding wheel  420 , i.e., the elevating operation plate  410 , depending on the kind of fabrics to be welded. Here, the degree of pressing of the welding wheel  420  against the fabrics is adjusted through the stroke of the elevating operation plate  410 . 
     Adjustment of the stroke distance is achieved by controlling rotation of the screw  441 , and the stopper  442 , into which the screw  441  is inserted, ascends and descends. 
     First, referring to  FIG.  9   , when fabrics  10  having a relatively small thickness t 1  are used, the welding wheel  420  is lowered more downwards than in the case in which fabrics having a general thickness are used, by descending the stopper  442 . 
     When the elevating operation plate  410  is lowered by operation of the elevating cylinder  220 , the latch  411  provided on the elevating operation plate  410  allows the cylinder rod  220   a  to descend to a long distance d 1  by the descent height of the stopper  442 , and the lowering stroke distance of the welding wheel  420  is also increased, thereby being capable of stably pressing the fabrics  10 . 
     Further, referring to  FIG.  10   , when fabrics  10  having a relatively large thickness t 2  are used, the welding wheel  420  is elevated upwards by ascending the stopper  442 . 
     When the elevating operation plate  410  is lowered by operation of the elevating cylinder  220 , the latch  411  provided on the elevating operation plate  410  allows the cylinder rod  220   a  to descend to a short distance d 2  by the ascent height of the stopper  442 , and the lowering stroke distance of the welding wheel  420  is also decreased, thereby being capable of stably pressing the fabrics  10 . 
     Further, in the present invention, the adjusted state of the stroke may be accurately measured by the scale  445 , and may be output. 
     That is, the measurement rod  446  of the scale  445  comes into contact with the scale measurement table  440  by ascent and descent of the stopper  442 , and thus measures the stroke distance, and more particularly, measures the lowering distance of the elevating operation plate  410  until the latch  411  is latched to the stopper  442 , and the stroke distance may be output through the main body  100  so that the adjusted state of the stroke may be accurately checked. 
     Thereafter, a method for welding the fabrics  10  in the state in which the stroke is adjusted, as described above, will be described. 
     Referring to  FIG.  11   , in order to weld the fabrics  10 , first, the elevating operation plate  410  is primarily lowered by operating the elevating cylinder  220 , and thereby, the welding wheel  420  is lowered to be close to the upper surface of the ultrasonic horn  330 . 
     Thereafter, the fabrics  10  to be welded are supplied, and concretely, the two fabrics  10  are loaded into the upper and lower fabric guides  430  and  430 ′, respectively. 
     Thereafter, welding is substantially performed, and concretely, the welding wheel  420  is secondarily lowered, and thereby, the welding wheel  420  is lowered to be closer to the ultrasonic horn  33  so as to press the fabrics  10  located between the welding wheel  420  and the ultrasonic horn  330 , and the welding wheel  420  and the ultrasonic horn  330  are rotated in opposite directions. 
     Further, together with operation of the welding wheel  420  and the ultrasonic horn  330 , the heater rod  520  is operated, and concretely, the lower end of the heater rod  520  is rotated from the right to the left in this figure by operation of the rotating cylinder  530 , and thus, the hot air discharge nozzle  520  is located between the upper and lower fabric guides  430  and  430 ′ and discharges hot air to the upper and lower fabric guides  430  and  430 ′ so as to heat the opposing surfaces of the upper and lower fabrics  10  to a designated temperature. 
     Thereafter, the fabrics  10  to be welded enter the gap between the ultrasonic horn  330  and the welding wheel  420 , and the supplied fabrics  10  enter the gap between the ultrasonic horn  330  and the welding wheel  420  in the state in which the fabrics  10  overlap each other, and are melted by frictional heat, and welded between the ultrasonic horn  330  and the welding wheel  420  by pressure. 
     Here, in the present invention, the supplied fabrics  10  are naturally supplied and discharged due to the rotational force of the ultrasonic horn  330  and the welding wheel  420  in opposite directions, and thereby, the fabrics  10  may be stably supplied and welded. 
     Further, in the present invention, smooth supply of the fabrics  10  may be implemented by structural improvement in the ultrasonic horn  330  and, as shown in  FIG.  12   , ultrasonic vibration energy transmitted from the booster  320  is transmitted to the front end of the body  340  of the ultrasonic horn  330 . 
     Thereafter, the ultrasonic vibration energy is transmitted to the head  350 , and concretely, is naturally transmitted to the vibration guide plate  351  of the head  350  through the connection curve part  352  connected to the front end of the body  340 , and is uniformly transmitted to the circumference of the vibration guide plate  351  through change of direction at a right angle in a disc shape. 
     Thereafter, the ultrasonic vibration energy transmitted to the vibration guide plate  351  is transmitted to the vibration radiation part  355 , and concretely, is naturally transmitted to the vibration radiation part  355  through the front and rear curve parts  353   a  and  353   b  formed on the circumference of the vibration guide plate  351 . 
     Thereby, the ultrasonic vibration energy transmitted to the vibration radiation part  355  is radiated through the front end surface thereof, i.e., the welding surface  356  forming the circumferential surface of the vibration radiation part  55 , and, when the radiated ultrasonic vibration energy is transmitted to the fabrics  10  between the ultrasonic horn  330  and the welding wheel  420 , frictional heat is momentarily generated on the bonding surface between the fabrics  10 , and a synthetic resin is melted and thus causes strong molecular bonding between the fabrics  10 . 
     As described above, the welding machine for synthetic resins according to the present invention may facilitate rapid welding of fabrics through preheating of the fabrics and concentrated molecular decomposition on the bonding surface between the fabrics, may achieve smooth entry and discharge of the fabrics through a structure in which both the ultrasonic horn and the welding wheel are rotated vertically in opposite directions, and may allow the stroke adjuster to easily adjust pressing force applied to the fabrics depending on the kind of the fabrics to be welded. 
     As is apparent from the above description, the present invention provides a welding machine for synthetic resins which may preheat the bonding surface between overlapping fabrics using a hot air generator and may successively perform welding of the fabrics using ultrasonic waves, and may thus achieve preheating of the fabrics to be welded using hot air and concentrated molecular decomposition on the bonding surface between the fabrics and welding of the fabrics using frictional heat caused by ultrasonic waves, thereby being capable of greatly improving workability in welding. 
     Further, the welding machine for synthetic resins according to the present invention is configured such that an ultrasonic horn is rotated vertically in an opposite direction to a welding wheel, which is rotated vertically, so as to radiate ultrasonic waves through the circumferential surface of the ultrasonic horn, and may thus achieve stable entry of the fabrics and prevent the fabrics from slipping during a process of welding the fabrics, thereby being capable of improving workability and minimizing defects in welding. 
     In addition, the welding machine for synthetic resins according to the present invention may facilitate stable welding of the fabrics depending on the thickness or the material of the fabrics through adjustment of the lowering stroke of the welding wheel. 
     Although the exemplary embodiments of the present invention have been disclosed for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims.