Patent Publication Number: US-2009236047-A1

Title: Mounting press device of tire mounting/dismounting apparatus

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a mounting press device for a tire mounting/dismounting apparatus that is used for exchanging a tire having high rigidity such as a low-profile tire by dismounting from or mounting on a wheel the tire. 
     2. Description of the Related Art 
     A tire mounting/dismounting apparatus called a tire changer or a tire exchanger has been used in order to exchange the tire of an automobile. The related art of this apparatus is described, for example, in Japanese Unexamined Patent Publication JP-A 2001-88518. In this related art, in order to solve a problem that the operation of dismounting and mounting a tire having high rigidity such as a low-profile tire from or on a wheel cannot be easily performed by one worker, a tire mounting/dismounting apparatus is constructed in the following manner: that is, a turntable on which a wheel is to be placed is disposed on a base so as to be rotatable around an shaft supported by the base; a wheel chucking device is disposed on the turntable; an insertion member body is disposed above the peripheral portion of the turntable; a mast erected on the side portion of the turntable has a pressing arm disposed thereon in such a way that the pressing arm can be angularly displaced and can move up and down; and the pressing arm has a press roller disposed thereon in such a way that the press roller can be changed to either a free state where the press roller can be rotated or a lock state where the press roller cannot be rotated. 
     When the tire is dismounted from the wheel rim, the pressing arm is moved down and the turntable is brought into a rotating state and the bead of the upper tire and side wall are pressed down by a bead pressing roller and the tire bead is dropped into the center drop of the wheel while rotating the turntable. At this time, the-bead pressing roller is in a free state where the press roller can rotate and rotates with the rotation of the tire and wheel. When the tire and wheel rotate one revolution, the entire periphery of the upper bead is dropped into the center drop of the wheel. 
     Then, the protrusion of a mounting head is inserted between the wheel rim and the upper bead. At this time, the upper bead near the insertion point where the protrusion is inserted is pressed down by a bead pressing roller to make the protrusion be easily inserted. Moreover, the upper bead and the side wall, which are opposite in a peripheral direction 180 degree to the insertion point of the protrusion of the mounting head, are pressed down by the bead pressing roller, and a tip portion of a tire lever is inserted by a worker between the wheel rim and the upper bead, which are near the mounting head, to bring the upper bead into a state where the upper bead is angularly displaced to be raised to an upper position than the wheel rim. When the turntable is rotated in this state, the upper bead can be pulled out upward from the wheel rim. 
     Next, when the peripheral portion of a lifting disk is inserted between the lower bead of the tire and the wheel rim and the turntable is rotated while moved up, the tire is pressed upward and the tire is dismounted from the wheel. 
     As described above, in the related art, the tire exchanger is constituted such that the tire can be dismounted from the wheel by one worker. 
     Moreover, when the tire is mounted on the wheel, the lower bead of the tire is fitted in the wheel from the upper rim of the wheel, and the mounting head is set at a position where the upper bead of the tire can be easily mounted on the wheel, and the bead pressing roller is bought into a lock state, and a swing arm is positioned in such a way that the center of rotation of the swing arm is arranged on the rotational axis of the turntable. After the positioning, the swing arm has turn locked, and the bead pressing roller is moved down along with the swing arm, and the tire is pressed at a position near the more downstream side in the rotational direction than the mounting head on the side wall of the tire to bring the bead pressing roller into a lock state so as to prevent the bead pressing roller from rotating by itself. When the turntable is rotated in this state, the bead pressing roller rotates along with the rotation of the turntable as the bead pressing roller presses the side wall of the tire, whereby the upper bead of the tire can be fitted inside the upper rim of the wheel by the mounting head and the bead pressing roller. 
     In this manner, in the related art, the tire mounting/dismounting apparatus is constructed such that when the tire is mounted on the wheel, the bead pressing roller has its rotation locked and is held pressed against the side wall of the tire following the rotation of the tire to thereby prevent the upper bead from being returning upward from the upper rim of the wheel by the resilient recovering force of the tire. With this, even in the case of a tire having high rigidity such as a low-profile tire, the tire can be mounted on the wheel by one worker. 
     In the related art, the mounting press device of the tire mounting/dismounting apparatus is constructed such that, when the tire is mounted on the wheel held by the turntable, the bead pressing roller is arranged at a position near a more downstream side in the rotational direction than the mounting head in a state where the bead pressing roller is prevented from rotating, and the swing arm is moved down to press the tire bead by the bead pressing roller to bring the tire into a state where the upper bead arranged above the upper side rim of the wheel is pressed down to a lower side than the upper side rim; and then, when the turntable is rotated in this state, the bead pressing roller is rotated as it presses the side wall of the tire and the mounting head drops the upper bead above the upper side rim down under the upper side rim to prevent the upper bead dropped under the upper side rim from returning again above the upper side rim by the resilient restoring force of the tire, whereby the upper bead on the entire portion in a circumferential direction can be fitted inside the upper side rim. However, in the case of a low-profile tire that is recently employed and reinforced by a metal wire or a carbon fiber and which has high rigidity, there happens the case in which only by pressing the side wall of the tire at one position by the bead pressing roller, the upper bead cannot be sufficiently relaxed at an upper bead fitting position where the upper bead is pressed and fitted by the mounting head but the upper bead once fitted under the upper side rim from above the upper side rim by the mounting head returns again above the upper side rim immediately after the upper bead is fitted under the upper side rim. Thus, there is presented the problem that the upper bead cannot be fitted under the upper side rim of the wheel with reliability. 
     SUMMARY OF THE INVENTION 
     An object of the invention is to provide a mounting press device of a tire mounting/dismounting apparatus capable of preventing a tire bead from being damaged and mounting a tire on a wheel with ease and with high speed even in the case where the tire is of high rigidity. 
     The invention provides a mounting press device of a tire mounting/dismounting apparatus, comprising: 
     a turntable for placing a wheel thereon, holding a wheel rim of the wheel so that the wheel rim can be removed from the turntable, and rotating the wheel rim around a vertical rotational axis; 
     a first moving up-and-down section disposed adjacently to the turntable, the first moving up-and-down section having a moving up-and-down body that is moved up and down along a moving path parallel to a rotational axis of the turntable; 
     a swing arm that is coupled to the moving up-and-down body of the first moving up-and-down section so as to be rotatable around a swing axis parallel to the rotational axis of the turntable; 
     a first arm that is coupled to the swing arm so as to be rotatable around a first axis parallel to the rotational axis of the turntable; 
     a second arm that is coupled to the swing arm so as to be rotatable around a second axis on a straight line common to the first axis; 
     a first pressing member that is disposed on the first arm so as to be movable along the first arm; 
     a second pressing member that is held by the second arm; and 
     a second moving up-and-down section which is disposed on the second arm so as to be movable along the second arm and moves up and down the second pressing member. 
     According to the invention, the tire is mounted on the wheel placed on the turntable, and the wheel rim of the wheel is held so that the wheel rim of the wheel can be removed from the turntable, and the wheel is rotated around the vertical rotational axis with the tire. 
     The first moving up-and-down section is disposed adjacently to the turntable and has the moving up-and-down body that is moved up and down along the moving path parallel to the rotational axis of the turntable. This moving up-and-down body has the swing arm coupled thereto in such a way that the swing arm can rotate around the swing axis parallel to the rotational axis of the turntable. This swing arm has the first arm and the second arm which are coupled thereto. The first arm is coupled to the swing arm so as to be rotatable around the first axis parallel to the rotational axis of the turntable, and the second arm is coupled to the swing arm so as to be rotatable around the second axis above the first arm. The first axis and the second axis form the common straight line. The first arm has the first pressing member disposed thereon in such a way that the first pressing member can move along the first arm. Moreover, the second arm holds the second pressing member and has the second moving up-and-down section that moves up and down the second pressing member. This second pressing member can also move along the second arm. 
     Thus, when the first pressing member and the second pressing member is positioned along the first and second arms so as to press the tire mounted on the wheel on the turntable and the moving up-and-down body is moved down by the first moving up-and-down section, the swing arm, the first arm, and the second arm that are disposed on the moving up-and-down body are moved down at the same time. When the first arm is arranged below the tire, the first pressing member of the first arm presses the tire bead. When the turntable is gradually rotated and the pressing position by the first pressing member is moved from a pressing starting position to the downstream side in the rotational direction, the second pressing member is moved down by the second moving up-and-down section to press the tire bead. In this manner, the tire is pressed by the first and second pressing members at plural different positions in the circumferential direction and hence the region of the tire bead, pressed by the first and second pressing members, can be pressed down to a position to face the center drop of the wheel rim. With this, the upper bead can be relaxed at a position where the upper bead is fitted onto the upper side rim by the mounting head or the like in the related art. Thus, even in the case of a tire having high rigidity, the upper bead can be fitted onto the upper side rim of the wheel and hence the work of mounting the tire on the wheel can be performed more easily and more speedily. 
     Moreover, in the invention, it is preferable that at least one of the first pressing member and the second pressing member is a roller to rotate around an axis crossing the rotational axis on an imaginary plane including the rotational axis of the turntable. 
     According to the invention, at least one of the first pressing member and the second pressing member can be realized by a roller, and the roller is rotatable around the axis crossing the rotational axis on the imaginary plane including the rotational axis of the turntable. Thus, even if at least one of the first arm and the second arm, which are provided with the rollers, is rotated with the rotation of the tire in a state where the roller is pressed against the tire bead, the roller is also rotated along the rotational direction of the tire. Hence, the direction in which the roller is rotated can be made to substantially coincide with the direction in which the tire bead is moved. This can prevent the roller from causing damage to the tire bead and can prevent a reduction in the hermeticity at the time of mounting the tire on the wheel. 
     Furthermore, in the invention, it is preferable that at least one of the first pressing member and the second pressing member is a pressing member shaped like a plate that has a tire pressing surface formed substantially in a flat plane along an imaginary plane perpendicular to the rotational axis of the turntable. 
     According to the invention, at least one of the first pressing member and the second pressing member is formed of the pressing member shaped like a plate, and this pressing member has the tire pressing surface formed substantially in the flat plane along the imaginary plane perpendicular to the rotational axis of the turntable. Thus, at least one of the first pressing member and the second pressing member can press the tire bead in a wide area, so that the contact pressure between the pressing member and the tire can be reduced and a force applied to the tire bead can be reduced. Hence, this can prevent the pressing member from causing damage to the tire bead. 
     According to the invention, the upper bead can be relaxed at the position where the upper bead is fitted onto the upper side rim by the mounting head in the related art. With this, even in the case of a tire having high rigidity, the upper bead can be fitted onto the upper side rim of the wheel and hence the work of mounting the tire on the wheel can be formed more easily and more speedily. 
     According to the invention, the direction in which the roller is rotated can be made to substantially coincide with the direction in which the tire bead is moved. This can prevent the roller from causing damage to the tire bead and hence can prevent a reduction in the hermeticity at the time of mounting the tire on the wheel. 
     According to the invention, at least one of the first pressing member and the second pressing member can press the tire bead in a wide area. Hence, this can reduce the contact pressure between the pressing member and the tire and can reduce a force applied to the tire bead and hence can prevent the pressing member from causing damage to the tire bead. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Other and further objects, features, and advantages of the invention will be more explicit from the following detailed description taken with reference to the drawings wherein: 
         FIG. 1  is a plan view showing a tire mounting/dismounting apparatus according to one embodiment of the invention; 
         FIG. 2  is a right side view, when viewed from a right side in  FIG. 1 , of the tire mounting/dismounting apparatus; 
         FIG. 3  is a left side view, when viewed from a left side in  FIG. 1 , of the tire mounting/dismounting apparatus; 
         FIG. 4  is a bottom view, when viewed from a bottom side in  FIG. 1 , of the tire mounting/dismounting apparatus; 
         FIG. 5  is a side view of a tire bead guide device; 
         FIG. 6  is a plan view of the tire bead guide device; 
         FIG. 7  is a front view, when viewed from a left side, of the tire bead guide device; 
         FIGS. 8A and 8B  are side views showing an action of an insertion member by an insertion member drive section; 
         FIGS. 9A to 9C  are sectional views showing a procedure of separating a tire bead from a wheel rim by an insertion part; 
         FIGS. 10A and 10B  are sectional views simplified so as to show an action of a bead pressing device,  FIG. 10A  showing a state in which a bead roller is arranged directly above the tire bead, and  FIG. 10B  showing a state in which the tire bead is pressed down by the bead roller; 
         FIG. 11  is a side view of a mounting press device; 
         FIG. 12  is a plan view of the mounting press device; and 
         FIGS. 13A and 13B  are views showing the operation of moving up and down a second pressing member by a second moving up-and-down section,  FIG. 13A  showing a state in which the second pressing member is arranged at an upper position, and  FIG. 13B  showing a state in which the second pressing member is arranged at a lower position. 
     
    
    
     DETAILED DESCRIPTION 
     Now referring to the drawings, preferred embodiments of the invention are described below. 
       FIG. 1  is a plan view showing a tire mounting/dismounting apparatus  1  according to one embodiment of the invention.  FIG. 2  is a right side view, when viewed from a right side in  FIG. 1 , of the tire mounting/dismounting apparatus  1 .  FIG. 3  is a left side view, when viewed from a left side in  FIG. 1 , of the tire mounting/dismounting apparatus  1 .  FIG. 4  is a bottom view, when viewed from a bottom side in  FIG. 1 , of the tire mounting/dismounting apparatus  1 . The tire mounting/dismounting apparatus  1  of this embodiment includes a tire bead guide device A, a bead pressing device B, and a mounting press device C. 
     First, the construction of the tire bead guide device A will be described. The tire bead guide device A includes a turntable  4 , an expandable arm  5  and an insertion member  8 . The turntable  4  places a wheel  2  thereon, holds a wheel rim  3  of the wheel  2  so that the wheel rim of the wheel  2  can be removed from the turntable  4 , and rotates the wheel rim  3  in a direction shown by an arrow D around a rotational axis L 1 . The expandable arm  5  is disposed so as to be displaceable above the turntable  4  in an upward direction away from the turntable  4  and in a downward direction close to the turntable  4  and so as to be displaceable above the turntable  4  in a forward direction close to the rotational axis L 1  of the turntable  4  and in a backward direction away from the rotational axis L 1  along a horizontal axis perpendicular to the rotational axis L 1 . The insertion member  8  has an insertion member body  6 . The insertion member body  6  is disposed on one end arranged closer to the rotational axis L 1  in a longitudinal direction of the expandable arm  5  so as to be angularly displaceable around an angular displacement axis L 2  perpendicular to an imaginary plane including an axis of the expandable arm  5 . The insertion member body  6  has an insertion part  7  disposed on one end arranged on the turntable  4  side with respect to the angular displacement axis L 2  of the insertion member body  6 , the insertion part  7  being inserted between the wheel rim  3  and the tire bead  26 . 
     The turntable  4  has a chuck section  50  for removably holding the wheel  2  placed with the rotational axis L 1 . This chuck section  50  has four engaging claws  51  disposed axisymmetrically with respect to the rotational axis L 1  and the respective engaging claws  51  are displaceably driven in directions close to and away from each other by a double-acting pneumatic cylinder (not shown). These engaging claws  51  can pinch a lower rim of the placed wheel  2  from the outside in a radial direction thereof and can hold the wheel  2  on the same axis as the rotational axis L 1 . Moreover, when the respective engaging claws  51  are displaced in the direction away from each other, the wheel  2  is released from a pinching state and hence can be removed from the turntable  4 . 
       FIG. 5  is a side view of the tire bead guide device A.  FIG. 6  is a plan view of the tire bead guide device A.  FIG. 7  is a front view, when viewed from the left side, of the tire bead guide device A. The tire bead device A further includes an insertion member drive section  9 , a spring biasing section  12 , a forward/backward drive section  10 , an upward/downward drive section  11 , and a forward/backward displacement preventing section (not shown). The insertion member drive section  9  is disposed on one end in the longitudinal direction of the expandable arm  5 , and has a plunger  9   a  that supports another end opposite to the one end of the insertion member body  6  with respect to the angular displacement axis L 2  from the outside in the radial direction with respect to the rotational axis L 1 . The spring biasing section  12  biases the insertion member  8  with a spring in the direction in which one end of the insertion member body  6  is close to the rotational axis L 1  of the turntable  4  and in which the other end of the insertion member body  6  is away from the rotational axis L 1 . The forward/backward drive section  10  displaceably drives the expandable arm  5  in the forward direction and in the backward direction. The upward/downward drive section  11  displaceably drives the expandable arm  5  in the upward direction and in the downward direction. The forward/backward displacement preventing section prevents the expandable arm  5  from being displaced in the forward direction and in the backward direction. The forward/backward displacement preventing section may be realized, for example, by keeping a state in which pressure chambers on both sides of the piston of the forward/backward drive section  10  are supplied with air of equal pressure. 
     The insertion member body  6  is made of steel or stainless steel and includes: a to-be-pressed portion  8   a  pressed by the plunger  9   a ; an attaching portion  8   b  connected to the to-be-pressed portion  8   a  in a bent form and extending toward an opposite side to the angular displacement axis L 2  and having the insertion part  7  removably and exchangeably disposed thereon with plural bolts  14 ; and a spring receiving portion  8   c  protruding from the attaching portion  8   b  in a direction opposite to a direction in which the plunger  9   a  presses the to-be-pressed portion  8   a  (the left direction in  FIG. 5 ). 
     The spring biasing section  12  is realized by a compression coil spring and is interposed between the spring receiving portion  8   c  and the expandable arm  5  and biases the insertion member body  6  in a direction in which its one end is close to the rotational axis L 1  and in which its other end is away from the rotational axis L 1 . 
       FIGS. 8A and 8B  are side views showing the action of the insertion member  8  by the insertion member drive section  9 .  FIG. 8A  shows a state in which the plunger  9   a  is extended to move the insertion part  7  backward in the direction away from the rotational axis L 1 .  FIG. 8B  shows a state in which the plunger  9   a  is retracted to move the insertion part  7  forward in the direction close to the rotational axis L 1 . The insertion member drive section  9  is realized by a double-acting pneumatic cylinder and can extend/retract the plunger  9   a  to angularly displace the insertion member  8  around the angular displacement axis L 2  in the direction in which its one end is away from the rotational axis L and in which its other end is close to the rotational axis L 1 . 
     The insertion part  7  includes: a base portion  16  formed in a shape tapered in a direction away from the insertion member body  6 ; a first portion  17  connected to the base portion  16  and extending in the direction away from the rotational axis L 1 ; and a second portion  18  connected to the first portion  17  and extending in the direction away from the angular displacement axis L 2 . The insertion part  7  is made of synthetic resin. 
     The construction of the bead pressing device B will be described. Referring again to  FIGS. 1 to 3 , the bead pressing device B includes a bead pressing arm  20 , a bead roller  21  and a roller moving section  22 . The bead pressing arm  20  is disposed so as to be displaceable above the turntable  4  in the upward direction away from the turntable  4  and in the downward direction close to the turntable  4  and so as to be displaceable above the turntable  4  in the forward direction E 1  close to the rotational axis L 1  of the turntable  4  and in the backward direction E 2  away from the rotational axis L 1  along a horizontal axis perpendicular to the rotational axis L 1 . The bead roller  21  is held by one end arranged closer to the rotational axis L 1  in the longitudinal direction of the bead pressing arm  20  and is disposed so as to be rotatable in a state of pressing down the tire bead  26  of a tire T placed on the turntable  4 . The roller moving section  22  is disposed on one end in the longitudinal direction of the bead pressing arm  20  and moves the bead roller  21  in the direction E 1  close to the rotational axis L 1  and in the direction E 2  away from the rotational axis L 1 . 
     The bead roller  21  has an outer peripheral surface  21   a  shaped like a truncated cone and is disposed so as to be rotatable around a roller axis L 3  with its bottom surface faced the rotational axis L 1  which, as it extends downward, is inclined in a direction away from the rotational axis L 1  on a vertical imaginary plane including an axis L 4  of the bead pressing arm  20  and the rotational axis L 1  of the turntable  4 . 
     Next, the construction of the mounting press device C will be described. The mounting press device C includes a first moving up-and-down section  31 , a swing arm  32 , a first arm  33 , a second arm  34 , a first pressing member  35 , a second pressing member  36  and a second moving up-and-down section  37 . The first moving up-and-down section  31  is disposed adjacently to the turntable  4  and has a moving up-and-down body  30  that is moved up and down along a moving path parallel to the rotational axis L 1  of the turntable  4 . The swing arm  32  is coupled to the moving up-and-down body  30  of the first moving up-and-down section  31  so as to be rotatable around a swing axis L 10  parallel to the rotational axis L 1  of the turntable  4 . The first arm  33  is coupled to the swing arm  32  so as to be rotatable around a first axis L 11  parallel to the rotational axis L 1  of the turntable  4 . The second arm  34  is coupled to the swing arm  32  at a position higher than the first arm  33  so as to be rotatable around the first axis L 11 . The first pressing member  35  is disposed on the first arm  33  so as to be movable along the first arm  33 . The second pressing member  36  is held by the second arm  34 . The second moving up-and-down section  37  is disposed on the second arm  34  so as to be movable along the second arm  34  and moves up and down the second pressing member  36 . 
     The first and second pressing members  35 ,  36  are realized by a roller that is shaped like a right circular column and which is rotatable around an axis crossing the rotational axis L 1  of the turntable  4  on an imaginary plane including the rotational axis L 1 . Moreover, the first and second moving up-and-down sections  31 ,  37  are realized by a double-acting pneumatic cylinder. In the other embodiments of the invention, at least one of the first and second pressing members  35 ,  36  may be formed of a pressing member shaped like a plate and having a tire pressing plane that is substantially flat along the imaginary plane perpendicular to the rotational axis L 1  of the turntable  4 . 
     According to this embodiment, the wheel  2  is placed on the turntable  4 , and the wheel rim  3  of the wheel  2  is held by the turntable  4  so that the wheel rim  3  of the wheel  3  can be removed from the turntable  4 , and the wheel rim  3  is rotated around the substantially vertical rotational axis L 1 . Moreover, the expandable arm  5  is displaceable above the turntable  4  in the upward direction away from the turntable  4  and in the downward direction close to the turntable  4  and is displaceable above the turntable  4  in the forward direction close to the rotational axis L 1  of the turntable  4  and in the backward direction away from the rotational axis L 1  along the horizontal axis perpendicular to the rotational axis L 1 . 
       FIGS. 9A to 9C  are sectional views showing the procedure of separating the tire bead  26  from the wheel rim  3  by the insertion part  7 .  FIG. 9A  shows a state in which the tire bead  26  is pressed down by the insertion part  7 , and  FIG. 9B  shows a state in which the tire bead  26  is engaged with the insertion part  7 , and  FIG. 9C  shows a state in which the tire bead  26  is separated above the wheel rim  3 . When the tire is separated from the wheel  2  in a state in which the insertion part  7  is attached to the insertion member body  6 , as shown in  FIG. 9A , the expandable arm  5  is moved down and positioned while being adjusted in the forward direction and in the backward direction in such a way that the insertion part  7  reaches near the wheel rim  3  of the tire bead  26  of the tire placed on the turntable  4 , and when the expandable arm  5  is further moved down from a state in which the insertion part  7  is in contact with the tire bead  26 , the tire bead  26  is pressed down by the insertion part  7 , thereby being separated from the wheel rim  3 . 
     When the plunger  9   a  is retracted in this state, as shown in  FIG. 9B , the insertion member body  6  is angularly displaced by the spring force of the spring biasing section  12  in the direction in which its other end is away from the rotational axis L 1  and in which its one end is close to the rotational axis L 1 , and the insertion part  7  is displaced in the direction close to the wheel rim  3 . As the expandable arm  5  is gradually further moved down, the insertion part  7  engages with the tire bead  26  at a position close to the center drop portion of the wheel rim  3 . With this, even if the tire T is a tire having high rigidity that has a low profile and is reinforced by a metal wire, the insertion part  7  can be inserted between the tire bead  26  and the wheel rim  3  in a state where the insertion part  7  is sufficiently close to the wheel rim  3 . Thus, the insertion part  7  can be smoothly inserted without pressing the tire bead  26  by a large pressing force by the insertion part  7 , which can prevent the tire bead  26  from being damaged when the insertion part  7  is inserted. 
     In this manner, the insertion part  7  can be inserted between the tire bead  26  and the wheel rim  3  at a position as close to the outer peripheral surface of the wheel rim  3  as possible. Thus, the tire bead  26  is not pressed with a larger force than is necessary and is prevented from having a scratch defect or a scratch mark caused by the contact with the insertion part  7 . Thus, the damage of the tire can be significantly reduced than ever before. 
     Moreover, when the tire bead  26  is separated from the wheel rim  3 , the insertion member  8  does not apply large force to the tire bead  26 . Thus, the insertion part  7  can be smoothly inserted between the tire bead  26  and the wheel rim  3 , which can facilitate and speed up the operation of exchanging the tire. 
     Further, the insertion part  7 , as shown in  FIG. 9C , has the base portion  16 , the first portion  17 , and the second portion  18 . The base portion  16  is formed in the shape tapered in the direction away from the insertion member body  6 , so that when the insertion part  7  is inserted between the tire bead  26  and the wheel rim  3 , the interference of the insertion part  7  with the surrounding members can be reduced and the inserted portion of the insertion part  7  can be visually checked with ease from the outside by the worker. The first portion  17  is connected to the base portion  16 , and the second portion  18  is connected to the first portion  17 . The first portion  17  extends in the direction away from the rotational axis L 1  of the turntable  4 , and the second portion  18  extends in the direction away from the angular displacement axis L 2  of the insertion member body  6 . Thus, the tip portion of the insertion part  7  is formed in a substantially S-shape in a cross section perpendicular to the angular displacement axis L 2 . 
     Since the insertion member  8  is provided with the insertion part  7 , when the insertion part  7  is inserted between the tire bead  26  and the wheel rim  3 , first, the second portion  18  is inserted between the tire bead  26  and the wheel rim  3 , and then the first portion  17  is moved down near the wheel rim  3 , and in this state, the expandable arm  5  is displaced and adjusted in the forward direction and in the backward direction in such a way that the base portion  16  is close to the wheel rim  3 . Then, when the plunger  9   a  of the insertion member drive section  9  is retracted to incline the second portion  18  so as to face the tire bead  26  and the expandable arm  5  is moved down, the tire bead  26  climbs over the second portion  18  and engages with a stepped portion formed in a substantially L-shape by the first portion  17  and the base portion  16 . When the expandable arm  5  is moved up in this state, even in the case of a tire having high rigidity, the tire bead  26  of the tire can be pulled up above the wheel rim  3  by one worker in a short time without using a tire lever as in the case of the related art and the tire can be separated from the wheel  2 . 
     Further, the expandable arm  5  is displaceably driven in the forward direction and in the backward direction by the forward/backward drive section  10  and is displaceably driven in the upward direction and in the downward direction by the upward/downward drive section  11  and is prevented from being displaced in the forward direction and in the backward direction by the forward/backward displacement preventing section. 
     Since the expandable arm  5  is displaceably driven in the forward direction and in the backward direction and in the upward direction and in the downward direction by the forward/backward drive section  10 , the expandable arm  5  can be displaced in the forward direction and in the backward direction in such a way that the insertion part  7  of the insertion member  8  is arranged in the vicinity directly above the position between the wheel rim  3  and the tire bead  26  above the turntable  4 , whereby the insertion part  7  can be positioned. 
     Still further, since the expandable arm  5  is displaceably driven in the upward direction and in the downward direction by the upward/downward drive section  11 , the expandable arm  5  can be moved up and down in such a way that the insertion part  7  is arranged between an upward position upper than the tire and the wheel  2  on the turntable  4  and a downward position where the insertion part  7  is inserted between the wheel rim  3  and the tire bead  26 . 
     In this manner, since the expandable arm  5  can be displaced in the forward direction and in the backward direction by the forward/backward drive section  10  and can be displaced in the upward direction and in the downward direction by the upward/downward drive section  11 , the worker does not need to move the insertion member  8  fixed to the expandable arm  5  directly by the manual operation, but the insertion member  8  can be moved from an insertion position between the wheel rim  3  and the tire bead  26  to an arbitrary position or from an arbitrary position to the insertion position. With this, the work load applied to the worker at the time of mounting and dismounting the tire can be reduced and the operation time required to perform the operation of mounting and dismounting the tire can be reduced. 
     By providing the forward/backward displacement preventing section, after arranging the expandable arm  5  at an arbitrary position in the forward direction and in the backward direction by the forward/backward drive section  10 , the forward/backward displacement preventing section can prevent the expandable arm  5  from being displaced in the forward direction and in the backward direction. Thus, even when the expandable arm  5  is prevented from being displaced in the forward direction and in the backward direction in a state in which the insertion part  7  is inserted between the wheel rim  3  and the tire bead  26  and the plunger  9   a  of the insertion member drive section  9  is extended, the expandable arm  5  can be prevented from being displaced in the backward direction by a reactive force that the insertion member  8  receives from the tire bead  26 . Hence, even in the case of the tire having high rigidity, the tire bead  26  can be surely separated from the wheel rim  3 . 
     Further, since the insertion member  8  is biased with the spring by the spring biasing section  12 , when the insertion part  7  is inserted between the tire bead  26  and the wheel rim  3  and then the expandable arm  5  is moved up to separate the tire bead  26  above the wheel rim  3 , even if the expandable arm  5  is moved up in a state where the insertion part  7  is in contact with the wheel rim  3 , the insertion member body  6  can be angularly displaced against the spring force of the spring biasing section  12  in the direction in which the one end of the insertion member body  6  is away from the rotational axis L 1  of the turntable  4  and in which the other end thereof is close to the rotational axis L 1  of the turntable  4 . With this, it is possible to prevent the insertion part  7  from being put into contact with the wheel rim  3  with a large force to cause damage to the wheel rim  3 . 
     Still further, since the insertion member  8  is biased by the spring of the spring biasing section  12 , even if the expandable arm  5  is moved down or up in a state where the expandable arm  5  is extended at a position in which the insertion part  7  is always in contact with the wheel rim  3 , as described above, the insertion part  7  can be close to or away from the rotational axis L 1  of the turntable  4  along the wheel rim  3 , and hence the speed with which the insertion part  7  is moved up and down can be increased. 
       FIGS. 10A and 10B  are sectional views simplified so as to show the action of the bead pressing device B.  FIG. 10A  shows a state in which the bead roller  21  is arranged directly above the tire bead  26 , and  FIG. 10B  shows a state in which the tire bead  26  is pressed down by the bead roller  21 . The bead roller  21 , as shown in  FIG. 10A , is arranged close to the wheel rim  3  directly above the tire bead  26  of the tire T placed on the turntable  4  along with the wheel  2  and can be rotated around the roller axis L 3  in a state where the bead roller  21  presses down the tire bead  26  at this pressing position. Thus, when the tire T mounted on the wheel  2  is rotated around the rotational axis L 1  on the turntable  4 , the bead roller  21  is also rotated around the roller axis L 3  along with the rotation of the tire T. When the bead pressing arm  20  is moved down in this state, as shown in  FIG. 10B , the tire bead  26  is rotated in the circumferential direction while being pressed down by the bead roller  21 . Thus, even in the case of the tire T having high rigidity, the bead roller  21  can press the tire bead  26  with large force and can press in the tire bead  26  from the wheel rim  3  to an inner drop  6   b , thereby being able to surely separate the tire bead  26  from the wheel rim  3 . 
     Further, the bead pressing arm  20  can be displaced in the direction E 1  close to the rotational axis L 1  of the turntable  4  and in the direction E 2  away from the rotational axis L 1 . Thus, the bead pressing arm  20  can be moved in the direction E 1  close to the rotational axis L 1  of the turntable  4  or in the direction E 2  away from the rotational axis L 1  in such a way that the bead roller  21  is arranged at a position where the tire bead  26  is pressed by the bead roller  21 , for example, directly above a position near the wheel rim  3  of the tire bead  26 . With this, the bead roller  21  can be positioned at a pressing position with precision. 
     Still further, the roller moving section  22  disposed on one end in the longitudinal direction of the bead pressing arm  20  can move the bead roller  21  in the direction E 1  close to the rotational axis L 1  and in the direction E 2  away from the rotational axis L 1 . Thus, when the bead pressing arm  20  is moved down in a state in which the bead roller  21  is arranged directly above the pressing position of the tire bead  26  by the bead pressing arm  20 , the bead roller  21  reaches to tire bead  26  as shown in  FIG. 10A  and starts to press down the tire bead  26 . When the bead roller  21  is moved in the direction E 1  close to the rotational axis L 1  by the roller moving section  22  at this time, a portion  21   a  arranged closest to the rotational axis L 1  of the bead roller  21  is arranged at a position closer to the wheel rim  3 . With this, the bead roller  21  can press down the tire bead  26  deeply at the pressing position, thereby being able to surely separate the tire bead  26 , which is in close contact with the wheel rim  3  on the more upstream side in the rotational direction D than this pressing position, from the wheel rim  3 . 
     Still further, the bead roller  21  has its outer peripheral surface formed in the shape of a truncated cone in which its bottom surface faces the rotational axis L 1  of the turntable  4 . Moreover, this bead roller  21  has its axis L 3  which, as it extends downward, is inclined in a direction away from the rotational axis L 1  on an imaginary plane including the axis L 4  of the bead pressing arm  20  and the rotational axis L 1  of the turntable  4  and is disposed so as to be rotatable around this roller axis L 4 . 
     Since the bead roller  21  formed in the shape of the truncated cone is disposed so as to be inclined in this manner, the outer peripheral surface of the bead roller  21  can be put into contact with the large area of the tire bead  26  and the bead roller  21  does not apply a large sliding and frictional force to the tire bead  26  in a direction different from a tangent direction at the pressing position in which the bead roller  21  presses the tire bead  26 . With this, even if the bead roller  21  presses the tire bead  26  with a large force, the bead roller  21  does not apply a large force locally to the tire bead  26  and the sliding and frictional force produced when the bead roller  21  slides on the tire bead  26  in a direction different from the tangent direction becomes small, which can prevent the tire bead  26  from being damaged by the bead roller  21 . 
     Still further, since the outer peripheral surface of the bead roller  21  is formed in the shape of the truncated cone, even if the bead roller  21  is moved by the roller moving section  22  in the direction E 1  close to the rotational axis L 1  of the turntable  4  at a position close to the wheel rim  3 , the bead roller  21  can be prevented from interfering with the wheel rim  3 . Thus, it is possible to press down the tire bead  26  near to the wheel drop and hence to separate the tire bead  26  from the wheel rim  3  with more reliability. 
       FIG. 11  is a side view of the mounting press device C.  FIG. 12  is a plan view of the mounting press device C.  FIGS. 13A and 13B  show the operation of moving up and down the second pressing member  36  by the second moving up-and-down section  37 , and  FIG. 13A  shows a state in which the second pressing member  36  is arranged at an upper position and  FIG. 13B  shows a state in which the second pressing member  36  is arranged at a lower position. As described above, the mounting press device C has the first and second pressing members  35 ,  36 , and the second pressing member  36  of at least one of the respective pressing members  35 ,  36  is moved up and down by the second moving up-and-down section  37  between the upper position higher than the tire T and wheel  2  placed on the turntable  4  as shown in  FIG. 13A  and the lower position to which the tire bead  26  placed on the turntable  4  is pressed down as shown in  FIG. 13B . 
     In the case where the upper bead  26  of the tire T is mounted on the wheel rim  3 , when the axis of the expandable arm  5  of the tire bead guide device A is assumed to be 0°, the second pressing member  36  is moved down from the upper position shown in  FIG. 13A  to the lower position shown in  FIG. 13B  at the position of 90° on the downstream side in the rotational direction D of the turntable  4  to press the tire bead  26  to the wheel drop. 
     Next, when the turntable  4  is rotated until the second arm  34  is moved to the position of 180° on the more downstream side in the rotational direction D than the expandable arm  5  of the tire bead guide device A, the tire bead  26  is not pressed down to the wheel drop at a position near the downstream side at the angle of 90° in the rotational direction D from the expandable arm  5  but is moved upward to the surface portion of the wheel rim  3 . Then, the tire bead  26  near downstream side at the angle of 90° in the rotational direction D of the tire is further pressed by the use of the second pressing member  36  and the turntable  4  is intermittently rotated with the tire bead  26  held pressed. With this, even in the case of the tire T having high rigidity, the tire T can have the upper bead fitted in the wheel rim  3 . 
     The invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description and all changes which come within the meaning and the range of equivalency of the claims are therefore intended to be embraced therein.