Abstract:
A tire changing machine having a support frame, rotatable supporting device for a wheel rim, locking device for securing the wheel rim to the supporting device, a fitting tool which can be secured to an adjustable tool supporting arm carried by the support frame, and driving device for the rotatatable supporting device. The machine also includes a first and a second pressure members which can be located in diametrically opposite positions with respect to a wheel rim carried by the supporting device and are designed to act on either side of a tire on the wheel rim, and drive device for actuating, upon control, each of the first and second pressure members.

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to a tire changing machine for industrial vehicle wheels. 
     As it is known, despite considerable progress in recent decades in terms of automation of tire fitting, bead release and tire removing operations, fitting and removal of industrial vehicle tires still require considerable manual effort and great skill by the operator, who must intervene several times in a tire fitting or removal operation with the risk of injuring himself. 
     SUMMARY OF THE INVENTION 
     The main object of the present invention is to provide a new tire changing machine suitable for performing in a substantially automatic manner various operations including gripping a wheel rim-tire assembly or just the wheel rim, fixing it in position and fitting bead release and removing of the tire. 
     Another object of the present invention is to provide a tire changing machine which is of universal use for wheels of flanged-rim, inverted-channel or bead-wire type. 
     Another object of the present invention is to provide a new bead release or breaking away and removal method which is highly effective and fast to be carried out. 
     According to a first aspect of the present invention, there is provided a tire changing machine which has a support frame, rotatable supporting means for a wheel rim, locking means for securing said wheel rim to said supporting means, a fitting tool securable to an adjustable tool supporting arm carried by said support frame, and driving means for said rotatable supporting means, and is characterized in that it comprises at least one first and second pressure rollers which can be located in diametrically opposite positions with respect to a wheel rim carried by said supporting means and are arranged to act on either side of the wheel rim, and control means designed to act, upon control, on each said first and second rollers. 
     Advantageously, said supporting means comprises a flange-type mandrel assembly for supporting a wheel rim, said mandrel assembly is telescopic and arranged with its axis of rotation at a relatively small angle with respect to the horizontal, and can be raised and lowered in order to adapt to various wheel rim dimensions. 
     According to another aspect of the present invention, there is provided a method of releasing or breaking away the bead of a tire rigidly coupled to a rotating support and of removing said tire, said method being characterized in that it comprises: 
     applying to a tire at least one pair of bead releasing rollers which are arranged diametrically opposite to one another while acting on opposite sides on said tire; 
     rotating the tire while said bead releasing rollers apply mutually opposite but staggered pressures in order to break-away the bead of the tire on both sidewalls; and 
     stopping the pressure action of one of the bead breaker rollers while the other one is still pressing against the tire until removal from the wheel rim is completed. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Further aspects and advantages of the tire changing machine according to the present invention will become better apparent from the following detailed description of a few currently preferred embodiments thereof, illustrated only by way of non-limitative example with reference to the accompanying drawings, wherein: 
     FIG. 1 is a perspective view slightly from above of a tire changing machine according to the invention; 
     FIG. 2 is a front view of the machine of FIG. 1; 
     FIG. 3 is a perspective view of the machine of FIG. 1, with parts removed and with no wheel rim; 
     FIG. 4 is a side elevation view, with portions shown in cross-section taken from the opposite side with respect to that shown in FIG. 1; 
     FIG. 5 is a perspective view of a mandrel and gearmotor assembly of the machine of FIG. 1; 
     FIG. 6 is a front view slightly from above, with parts cut away, illustrating a fitting operation of the machine of FIG. 1; 
     FIG. 7 is a top view, with parts cut away to illustrate a bead breaking and removal operation; 
     FIG. 8 is a partial front view, with parts shown in cross-section, of the machine of FIG. 1; 
     FIG. 9 is a view of a detail relating a tool of the machine of FIG. 1; 
     FIGS. 10 and 11 are a front elevation view and a plan view, respectively, of the tool of FIG. 9; and 
     FIG. 12 is a perspective view of an expansion mandrel assembly for locking a wheel rim in its working position. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     In the accompanying drawings, identical or similar parts or components have been designated by the same reference numerals. 
     With reference first to the above figures, it will be noted that a tire changing machine according to the invention, generally designated by the reference numeral  1 , is constituted by: a support frame  2 , a mandrel assembly  3  acting as a rotating support for a wheel rim  4 , a fitting tool  6  securable to a tool supporting arm  7 , which is adjustable in position and is supported by the support frame  2 , a pair of rollers: a front one  8  and a rear one  9 , which are arranged at diametrically opposite positions with respect to the wheel rim  4  when it is supported on the mandrel assembly  3 , said rollers being arranged on opposite sides with respect to the wheel rim  4 ; and a hydraulic assembly  5  and a gearmotor assembly  26  for actuating the movable components of the machine. 
     The support frame  2 , in the illustrated embodiment, comprises a base  2   a  which can be preferably fixed to the floor by means of lateral lugs  10  formed with an anchoring hole  11 . A shaped platform  12  is provided at the front side of the base, and a wheel rim  4  or a wheel with a tire  13  on it located and held in position to a certain extent owing to a recess  12   a  which is substantially axially aligned with the mandrel assembly  3 . 
     Two front uprights  14  and  15  and two rear uprights  16  and  17  extend upwards from the base  2   a  and are secured at the top thereof, to a stiffening frame  18 . 
     Advantageously, the axis of the mandrel assembly  3  extends so as to form a relatively small angle, of the order of 15-30 degrees, with respect to the horizontal, i.e. its front end, which is adjacent to the front uprights  14  and  15 , is at a higher level from the ground than its rear end. Moreover, in order to allow the mandrel assembly  3  to be adjusted to meet various sizes of the wheels and their respective wheel rims, the mandrel assembly can be raised and lowered along the front uprights  14  and  15 , which are thus correspondingly inclined backward with respect to the vertical. 
     To this purpose, along the internal side of each front upright  14  and  15  there are provided two mutually opposite and parallel guides  19  and  20 , along which a slide or a carriage  21  provided with four sliding rollers  23  is slideably mounted (FIG.  3 ). The carriage  21  rotatably supports, e.g. by interposition of suitable bearings (not shown in the drawings), the mandrel assembly  3 , which can also be raised and lowered owing to the action of a double-acting hydraulic jack  24  (FIG. 4) extending parallel to the front uprights and having one end thereof anchored to the base  2   a  and its other end connected to the slide  21 . 
     The actual mandrel  3  is preferably of telescopic type and is controlled to extend or retract by a double-acting hydraulic jack  25  which is preferably coaxial to said mandrel, whereby the mandrel can extend forward or retract with respect to the front uprights  14  and  15  in order to adjust itself to different types of wheel rim  4 , e.g. a flanged wheel rim or an inverted-channel rim or a multi-bead rim. 
     An assembly  26 , including an electric motor ME and a reduction unit RI for the mandrel  3  is arranged between the front and rear uprights, comprises a chain drive  27  between the reduction unit and the mandrel and a belt drive  27   a  between the electric motor and the reduction unit, and can be of any suitable type, as is known to a person skilled in the art. 
     At its front end the mandrel  3  has a flange  28  having steps  29  (FIG. 3) for supporting a wheel rim  4 , which must then be fixed onto the mandrel by means of a plate  31  which can be screwed onto the threaded front end of the mandrel. 
     If desired, the flange  28  is provided with expanding arms  30  (FIG. 12) for engaging and locking the internal flange of the wheel rim  4 . 
     The forward elongation of the mandrel  3  is utilized in combination with the possibility of moving up and down in order to adjust the mandrel to wheel rims  4  having different diameters, with or without a tire  13 . Each wheel rim, in the case of a stepped flange  28  located on the platform  12 , once it has been engaged at its central hole by the mandrel  3  inserted therein, is raised by the mandrel and, owing to the backward inclination of the mandrel, comes at rest against the flange  28  and is then rigidly secured to the mandrel by screwing onto it a locking plate  31 . 
     More particularly, again owing to the inclination of the mandrel  3  with respect to the horizontal, the wheel rim  4 , once it has been raised by the mandrel  3 , cannot fall forward with respect to the machine, which would be dangerous for the operator, but is urged immediately to rest against the flange  28  even before being fixed in position by means of the plate  31 , thus making the entire operation completely safe against accidents, which are not infrequent with conventional machines, since the wheel rims and wheel assemblies involved are usually of large dimensions and thus quite heavy. 
     Preferably, the frame  18  extends forward cantileverwise well beyond the front uprights  14  and  15  and supports, on the opposite side with respect to the longitudinal centerline of the machine, two rotating shafts  32  and  33  and a pivot  35 , all of which extend parallel to the mandrel  3  and are, for example, supported by suitable brackets  36 ,  37 ,  38  and  39  (FIG. 6) which are welded to the frame  18 . Shaft  32  is supported by the two brackets  36  and  37  and, in turn, supports a rotating sleeve  40  which is rigidly coupled, at its distal end, to a lug  41  which extends upward and is formed with a through hole  42 . 
     Two forks  43  and  44  are fixed, e.g. welded, to the sleeve  40  and spaced from one another and extend downwards. One end of an L-shaped arm  45  is articulated to the fork  44 , and at its other end a front roller  8 , which is preferably substantially a truncated cone in shape, is cantileverwise mounted for rotation, whereas one end of a linear actuator, such as a pneumatic double-acting jack  46  is linked to the fork  43 , the other end thereof being articulated to a transverse pivot  47  which is carried at the lower end of the arm  45 , e.g. by means of two lugs  48  welded to said arm. 
     With this configuration, when the hydraulic jack  46  is being elongated, the arm  45 , and thus the front roller  8 , are caused to be retracted in a direction substantially parallel to the vertical plane containing the mandrel  3 , whereas when said jack is being shortened the roller is pushed forward. 
     Similarly, the shaft  33  is supported by the pair of brackets  38  and  39  and, in turn, supports a rotating sleeve  49  which is rigidly coupled, at its proximal end, to a toothed sector  50 . Two mutually spaced and downwards extending forks  51  and  52  are fixed, e.g. welded, to the sleeve  49 . One end of an L-shaped arm  53  (FIG. 7) is articulated to the fork  51 , whereas at its other end the rear roller  9 , which is preferably substantially a truncated cone in shape, is cantileverwise mounted for rotation about an axis of rotation in common with a cylindrical roller  9   a . One end of a linear actuator, e.g. a hydraulic double-acting jack  54 , is linked to the fork  52 , whereas the other end of said actuator is articulated to a transverse pivot  55  which is supported at the lower end of the arm  53 , e.g. by means of two lugs  56  welded to said arm. 
     With this configuration, when the hydraulic jack  54  expands, the arm  53 , and thus the rear roller  9 , are pushed forwards in a direction substantially parallel to the vertical plane containing the mandrel  3 , whereas when said jack contracts itself, the roller  9  is shifted backwards against the tire  13 , as is better shown in FIG.  7 . 
     The toothed sector  50 , rigid with the sleeve  49 , meshes with a toothed sector  57  (FIGS.  2 , 3  and  7 ) which is pivoted at  58  to the frame  18  or to the bracket  39  and has an arm  59  which is linked to one end of a hydraulic double-acting jack  60  which is arranged above and astride the frame  18 , the other end of said jack being linked to the lug  41  rigid with the sleeve  40  on the other side of the machine. Thus, when the jack  60  is being elongated, the two arms  45  and  53  are caused to move closer to one another near a respective side of the machine or the mandrel  3 , whereas when said jack is being shortened, said arms, and thus their respective rollers carried on them, are moved mutually apart, i.e., moved away from the sides of the machine or from the mandrel  3 . 
     As is more clearly shown in FIG. 3, two lugs  61  are secured, e.g. welded, to the sleeve  49  which extend downwards and support therebetween a nut or female thread  62  into which a threaded shaft  63  controlled by a handwheel  64  can be screwed. When the shaft  63  is screwed into the female thread  62 , it will protrude from it to abut against the frame  18  and act as a retainer for the arm  53 , which is then stopped while the jack  60  is being shortened, whereas, by reaction, the arm  45  can proceed, for a certain extent, with its stroke away from the mandrel  3 , as further explained hereinafter. 
     Preferably, the front arm  45  (FIGS. 1 to  4 ) supports, also in a forward position quite comfortable for an operator, two knobs  65  and  66  which are provided with control buttons  67  and supported, e.g. by a U-shaped support  68  which, in turn, carries a control panel  69  and is supported at one end of a cantilever arm  70  whose other end is fixed to the arm  45 . 
     The fitting tool  6  can be arranged at the free end of the tool holder arm  7 , whose other end is articulated to the pivot  35  so that it can perform forward and backward sliding strokes in order to adapt itself to various widths of wheel rims  4 . More particularly, the arm  7  (FIG. 6) is formed by a first section  7   a  which is linked, at one end thereof to the pivot  35  and terminates, at its other end, with a fork  7   b , to which one end of a second section  7   c , is pivoted, which is e.g. L-shaped and provided with a control knob  7   d . The arm  7  thus structured allows the tool  6  to be moved, as shown more clearly in FIG. 1, to a working position which is offset by approximately 90 degrees with respect to the working position of the roller  8  and on the same side with respect to a wheel rim  4  fitted on the mandrel assembly  3  but on the opposite side with respect to the rear roller  9 . 
     On its part designed to contact the edge of the wheel rim  4 , the tool  6  is coated with, or has otherwise applied thereto, a layer of a suitable, tough, self-lubricating plastic material, e.g. nylon (registered ™) reinforced with glass fiber, thereby avoiding deforming or otherwise damaging the wheel rim  4 . 
     The operation of the above-described tire changing machine is as follows. 
     A distinction should be made between two main operations, namely mounting of a tire and bead breaking and removal of an already-mounted tire. 
     For a tire mounting operation, the tool  6  and the front roller  8  are used as shown in FIGS. 1 and 6. It will be noted that tool  6  is angularly spaced from the working position of the roller  8  of about 90 degrees. The wheel rim  4  is located in position by causing it to roll or by placing it in the recess  12   a  of the platform  12 . The operator, by acting on the buttons  67  of the knobs  65  and  66 , controls by following a suitable control sequence the jacks  24  and  25 , thereby causing the mandrel  3  to be lowered or raised to the level of the central hole in the wheel rim  4  located on the platform  12  and inserted into it to positively engage it. The mandrel  3  is then raised and the wheel rim  4  is lifted with it, so that the wheel rim, owing to the inclination of the mandrel with respect to the horizontal, rests against the flange  28  and is lifted. 
     The operator then locks the wheel rim on the mandrel assembly by screwing the plate  31  onto the mandrel, thus clamping the wheel rim  4  against the flange  28  so that it becomes rigid in rotation with the mandrel. 
     A tire  13  is then drawn near to the wheel rim and rests with its bead on it. The mandrel assembly is further lifted, together with the tire, until the tire  13  is raised above the platform  12 . By acting on controls  67 , the front roller  8  is then located in such a way as to push the tire  13  (FIG. 6) beyond the edge of the wheel rim  4 . The tool  6  is then located in its working position by acting on the knob  7   d , at 90 degrees with respect to the roller  8  and by inserting the tip of the tool between the edge of the wheel rim and the bead of the tire  13 . 
     The operator by energizing electric motor ME sets then the mandrel in rotation in the direction of the arrow A in FIG.  6 . Simultaneous combined action of the roller  8 , which presses against the sidewall of the tire  13  to push it inwards, i.e., toward the flange  28 , and of the tool  6 , which causes the tire bead to move to the inside edge of the wheel rim, results in a rapid mounting of the tire  13  onto the wheel rim  4 . 
     For a bead breaking or release and removal operation, reference should be made in particular to FIG. 7, which shows two rollers, i.e., front roller  8  and rear roller  9 , being used. The said rollers are arranged in diametrically opposite working positions on opposite sides with respect to the tire  13  to be removed. In other words, one roller acts on the front sidewall and the other roller acts on the rear sidewall of the tire, thus applying a powerful and effective unseating action onto the tire. It will be noted, in this regard, that the wheel rim with the tire is caused to rotate in the direction of arrow B, and that the roller  9   a  assists the action of the mainly bead-breaking roller  9  by applying pressure in a region which is at a diametrically larger distance from, and therefore more effective on, the sidewall of the tire, thereby forcing it to come out of the wheel rim  4 . 
     Once removal has been completed, the mandrel  3  is lowered in order to move away the removed tire from the wheel rim which is then ready to possibly receive another tire to be mounted onto it. 
     The disclosures in Italian Patent Application No. VR99A000033 from which this application claims priority are incorporated herein by reference.