Patent Publication Number: US-2022219919-A1

Title: Linear conveyor

Description:
TECHNICAL FIELD 
     The technology described herein relates to a linear conveyor. 
     BACKGROUND ART 
     There has been known a linear conveyor that moves a transfer slider along a rail. This type of linear conveyor includes a base member, a unit-type fixed module that is fixed to the base member, a linear rail, and a stator including armature coils. The slider includes a rail guide that is guided along the rail and a rotor that is a permanent magnet. 
     The configuration disclosed in Patent Document 1 includes a fixed base, a gate-like frame extending along a longitudinal direction on the fixed base, and a pair of armatures. One of the armatures is fixed to the frame and the guide rail and another one of the armatures are fixed to the fixed base. The slider is movably supported by the guide rail. The fixed base and the frame include refrigerant holes through which refrigerant flows and are configured as a refrigerant jacket. The heat exchange is performed with the refrigerant for the heat generated by the armature coils to solve the problems such as thermal deformation of the guide rail. 
     PRIOR ART DOCUMENT 
     Patent Document 
     [Patent Document 1] 
     Japanese Unexamined Patent Publication No. 2004-64874 
     DISCLOSURE OF THE INVENTION 
     Problem to be Solved by the Invention 
     In the configuration disclosed in Patent Document 1, to solve the problem such as the thermal deformation of the guide rail, the refrigerant needs to be supplied through the refrigerant holes and a circulation pump for flowing the refrigerant is required and this complicates the configuration. 
     The technology described herein was accomplished in view of the foregoing circumstances. An object of the present technology is to provide a linear conveyor that can suppress problems caused by thermal deformation. 
     Means for Solving the Problem 
     A linear conveyor described herein is a linear conveyor fixed to a base member and the linear conveyor includes a transfer slider, a frame including a rail along which the transfer slider is moved in a traveling direction, a first support member that is disposed on one end side of the frame with respect to a longitudinal direction of the frame and is fixed to the base member and the frame and supports the frame, a second support member that is disposed on another end side of the frame with respect to the longitudinal direction of the frame and fixed to the base member and supports the frame such that the frame is not fixed with respect to the second support member, and a sliding mechanism with which the second support member and the frame relatively move in the longitudinal direction according to difference in thermal expansion and contraction amounts of the base member and the frame. 
     According to the above configuration, the frame is not fixed to the second support member on the other end side in the longitudinal direction of the frame. If the difference in the thermal expansion and contraction amounts is created between the base member and the frame, the warping or deflection of the frame due to the thermal expansion and contraction can be suppressed. Further, the linier conveyor includes the sliding mechanism with which the second support member and the frame relatively move in the longitudinal direction according to difference in thermal expansion and contraction amounts of the base member and the frame. Therefore, the position displacement of the frame in a direction different from the longitudinal direction (for example, in a lateral direction with respect to the longitudinal direction) is less likely to be caused in the portion thereof that is not fixed and near the second support member. Accordingly, the transfer slider can smoothly travel between the adjacent rails. 
     Embodiments of the technology described herein may preferably have following configurations. 
     The sliding mechanism may be fixed to one of the first support member and the second support member and include a fitting portion that is fitted to another one of the first support member and the second support member so as to be able to slide. 
     According to such a configuration, since the fitting portion is slidably fitted to the other one of the first support member and the second support member, occurrence of warping and deflection of the frame can be suppressed and the traveling between the adjacent rails can be performed smoothly with a simple structure. The sliding mechanism is not necessarily fixed directly to the base member. Therefore, the base member need not have a configuration (such as screw holes) for fixing the sliding mechanism and the sliding mechanism can be additionally installed in the existing configuration easily. 
     The sliding mechanism may include a tubular portion that is fixed to one of the second support member and the frame, and an insertion portion that is fixed to another one of the second support member and the frame and inserted in the tubular portion so as to be able to slide. 
     According to such a configuration, if the difference is created in the thermal expansion and contraction amounts of the base member and the frame, the position displacement in the direction different from the longitudinal direction is suppressed directly by the frame (not via the first support member). 
     The tubular portion may include a linear bushing that is slidable with respect to the insertion portion and a holder portion that holds the linear bushing. 
     According to such a configuration, the wearing between the inner surface of the tubular portion and the outer surface of the insertion portion can be suppressed. 
     The sliding mechanism may include an auxiliary rail that is directly fixed to one of the base member and the frame, and an auxiliary slider that is directly fixed to another one of the base member and the frame and slides with respect to the auxiliary rail. 
     According to such a configuration, the first support member or the second support member is not necessarily processed to provide the sliding mechanism. Therefore, the first support member or the second support member need not be prepared as an exclusive component and this reduces a manufacturing cost. The sliding mechanism can be additionally installed in the existing configuration easily. 
     The sliding mechanism may include an auxiliary rail that is directly fixed to one of the second support member and the frame, and an auxiliary slider that is directly fixed to another one of the second support member and the frame and slides with respect to the auxiliary rail. 
     According to such a configuration, the frame is not fixed to the second support member by including the auxiliary rails and the auxiliary slider, and this simplifies the configuration. 
     The linear conveyor may further include a fixed module including the frame, the first support member, the second support member, and the sliding mechanism, and a lifting and lowering device including a lifting and lowering frame including a lifting and lowering rail that is arranged linearly adjacent to the rail of the frame of the fixed module in an elongated direction, and the lifting and lowering device lifting and lowering the transfer slider. 
     According to such a configuration, the transfer slider is lifted or lowered by the lifting and lowering device. Therefore, in the configuration that requires position accuracy between the rails for smooth travel between the rails, problems are less likely to be caused in traveling between the rails. 
     Effects of Invention 
     According to the technology described herein, problems due to thermal deformation in the linear conveyor are less likely to be caused. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of a linear conveyor device including a linear conveyor according to a first embodiment. 
         FIG. 2  is a front view of the linear conveyor device. 
         FIG. 3  is a right side view of the linear conveyor device. 
         FIG. 4  is a cross-sectional view of a portion of the linear conveyor including a sliding mechanism taken along a X-Z plane. 
         FIG. 5  is an enlarged view of a portion of  FIG. 4 . 
         FIG. 6  is a cross-sectional view of a portion of the linear conveyor including the sliding mechanism taken along a Y-Z plane. 
         FIG. 7  is a cross-sectional view illustrating that the thermal expansion and contraction amount of a frame with respect to a base member changes from that in  FIG. 4 . 
         FIG. 8  is an enlarged view of a portion of  FIG. 7 . 
         FIG. 9  is a cross-sectional view of a portion of a linear conveyor including a sliding mechanism according to a second embodiment taken along a X-Z plane perspective view. 
         FIG. 10  is a cross-sectional view of a portion of the linear conveyor including the sliding mechanism taken along a Y-Z plane. 
         FIG. 11  is a cross-sectional view illustrating that the thermal expansion and contraction amount of a frame with respect to a base member changes from that in  FIG. 9 . 
         FIG. 12  is an enlarged view of a portion of  FIG. 11 . 
         FIG. 13  is a cross-sectional view of a portion of a linear conveyor including a sliding mechanism according to a third embodiment taken along a X-Z plane. 
         FIG. 14  is a cross-sectional view illustrating that the thermal expansion and contraction amount of a frame with respect to a base member changes from that in  FIG. 13 . 
         FIG. 15  is an enlarged view illustrating a portion of  FIG. 14 . 
     
    
    
     MODES FOR CARRYING OUT THE INVENTION 
     First Embodiment 
     A linear conveyor  10 A of a first embodiment will be described with reference to  FIGS. 1 to 8 . In the following description, an X-direction, a Y-direction, and a Z-direction in  FIG. 1  correspond to a left side, a front side, and an upper side, respectively. As illustrated in  FIG. 1 , the linear conveyor device  10  includes the linear conveyor  10 A and a base member  11  on which the linear conveyor  10 A is mounted. The linear conveyor  10 A moves a transfer slider  50  by linear motor driving. 
     The base member  11  includes a base body  12  made of metal such as iron and formed in a matrix and mounting plates  15  on which the linear conveyor  10  is mounted. The base body  12  includes legs  13  on a lower portion thereof and the legs  13  are placed on a floor, which is not illustrated. Each of the mounting plates  15  is a rectangular flat plate. The mounting plates  15  are fixed to the base body  12  at different levels and arranged in an area of the base body  12  except for the two end portions thereof in the longitudinal direction. Two lifting and lowering devices  80  for lifting and lowering the transfer slider  50  are arranged in areas in the base body  12  where the mounting plates  15  are not arranged. 
     (Whole Configuration of Linear Conveyor  10 A) 
     The linear conveyor  10 A includes fixed modules  20 , the two lifting and lowering devices  80 , and the transfer slider  50 . The fixed modules  20  are fixed on the mounting plates  15  of the base member  11  (three fixed modules  20  are disposed on the respective levels and six fixed modules  20  are disposed in total in the present embodiment). The lifting and lowering devices  80  are fixed to the base body  12 . 
     As illustrated in  FIG. 2 , the fixed modules  20  are arranged linearly on each of the upper and lower mounting plates  15 . As illustrated in  FIG. 4 , the fixed module  20  includes a metal frame  23 , a first support member  40 , a second support member  42 , and a sliding mechanism  60 . The first support member  40  is arranged in a right end portion of the frame  23  (on one end side in a longitudinal direction) and fixed to and supports the frame  23 . The second support member  42  is arranged in a left end portion of the frame  23  (on another end side in the longitudinal direction) and supports the frame  23  not to be fixed to the frame  23 . The sliding mechanism  60  allows relative sliding movement of the second support member  42  and the frame  23  in a right-left direction. 
     (Frame  23 ) 
     The frame  23  is obtained by cutting an extrusion molded object of metal such as aluminum alloy into a product of a predetermined length. The frame  23  extends to have a length of an entire length of the fixed module  20  in a traveling direction and has a same cross-sectional shape over the entire length thereof in the traveling direction. As illustrated in  FIG. 6 , the frame  23  includes a base body  23 A and a top cover  24 . The top cover  24  has a cross section of a substantially T-shape and includes a cover body  25  and a separation wall  26 . The cover body  25  has a plate shape and the separation wall  26  separates a space below the cover body  25 . The cover body  25  protects rails  28  from fallen obstacles and front and rear edge portions thereof are bent and extend downward. The base body  23 A includes mount portions  27  extending from front and rear edge portions of the base body  23 A, respectively, in the front-rear direction (edge portions with respect to the front-rear direction that is perpendicular to the longitudinal direction of the frame  23 ). A tubular portion  70  of the sliding mechanism  60 , which will be described later, is mounted on the mount portion  27 . 
     The base body  23 A includes right and left rails  28 , a stator  30 , and a magnetic sensor  31  in an upper surface portion thereof. The rails  28  guide the transfer slider  50  in the traveling direction. Each of the rails  28  extends linearly and is fitted in a guide recess  57  of the transfer slider  50  so as to guide the transfer slider  50  to slide linearly. As illustrated in  FIG. 4 , when the fixed modules  20  and the two lifting and lowering devices  80  that are disposed on the ends of a group of the fixed modules  20  are arranged in a line, the frames  23  (and rails  28 ) of the fixed modules  20  and lifting and lowering frames  81  of the respective lifting and lowering devices  80  (and lifting and lowering rails  81 A of the respective lifting and lowering frames  81 ) are linearly arranged. In such a configuration, a gap G is created between ends A 1 , B 1  of the adjacent frames  23 ,  81  and the gap G allows the frame  23  to be thermally expanded and contracted. The rails  28  may be integrally formed with the base body  23 A as a unitary part. However, rails may be provided as separate components from the base body  23 A and the rails  28  may be attached to the base body  23 A. 
     As illustrated in  FIG. 6 , the stator  30  is formed in an elongated rectangular cylindrical shape having a quadrangular end surface. The stator  30  includes armature coils therein that are arranged in the traveling direction of the transfer slider  50 . The transfer slider  50  is moved along the rails  28  and the stator  30  with the linear motor driving by controlling current supplied to the armature coils. The magnetic sensor  31  includes Hall element or a MR element that can detect a magnetic scale  59 . The magnetic sensor  31  is arranged opposite the magnetic scale  59  to detect the position of the transfer slider  50 . 
     (First Support Member  40  and Second Support Member  42 ) 
     The first support member  40  and the second support member  42  are made of metal such as aluminum alloy and have strength enough for supporting the weights of the frame  23  and the transfer slider  50 . The lower portion of the first support member  40  is fixed to the mounting plate  15  of the base member  11  with fixing members  44  such as bolts. As illustrated in  FIG. 4 , the upper portion of the first support member  40  is fixed (screwed) to the right end portion of the frame  23  (one end portion in the longitudinal direction) with a fixing member  45  such as a bolt. As illustrated in  FIG. 5 , the first support member  40  includes a fitting portion  41  in which an end portion of a shaft portion  61  of the sliding mechanism  60 , which will be described later, is fitted. The fitting portion  41  is a recessed portion recessed in a surface of the first support member  40  facing the second support member  42  and the recessed portion has a circular columnar space therein. The end portion of the shaft portion  61  can be fitted in the fitting portion  41  (while leaving a small space therein). 
     As illustrated in  FIG. 4 , the second support member  42  includes a metal case  42 A in which a circuit with a board is arranged. The lower portion of the second support member  42  is fixed to the mounting plate  15  of the base member  11  with the fixing members  44  such as bolts. The upper portion of the second support member  42  is not fixed to the left end portion (the other portion in the longitudinal direction) of the frame  23  with the fixing member such as a bolt and relative movement (position displacement) of the frame  23  and the second support member  42  are allowed. The gap G is provided between the adjacent fixed modules  20  (the frames  23 ) and between the fixed module  20  (the frame  23 ) and the lifting and lowering device  80  (the lifting and lowering frame  81 ) to absorb thermal expansion and contraction of the frame  23 . 
     (Transfer Slider  50 ) 
     As illustrated in  FIG. 6 , the transfer slider  50  includes an opposing portion  51 , two insertion portions  52 , and two connection portions  53 . The opposing portion  51  is opposite the cover body  25  of the top cover  24  of the frame  23 . The two insertion portions  52  are inserted in a space between the top cover  24  and the base body  23 A. The two connection portions  53  are formed in a U-shape and connect the opposing portion  51  and the respective insertion portions  52 . Rail guides  56  are fixed to the respective insertion portion  52  and have recesses opening downward. Each of the rail guides  56  includes a guide recess  57  extending in the traveling direction of the transfer slider  50 . The rails  28  are fit in the respective guide recesses  57  and balls (not illustrated) that are arranged in the guide recesses  57  are contacted with the rails  28  and rolled. 
     A rotor  58  including permanent magnets is arranged on one of the insertion portions  52  and the permanent magnets are arranged along the traveling direction of the transfer slider  50 . The magnetic scales  59  are arranged on another one of the insertion portions  52 . Each of the magnetic scales  59  includes a magnet such as a neodymium magnet and the magnetic scales  59  are arranged in the traveling direction of the transfer slider  50 . Each of the magnetic sensors  31  detects the opposing magnetic scale  59  and detects the position of the transfer slider  50 . 
     The transfer slider  50  is moved by driving the fixed modules  20  and the two lifting and lowering devices  80 . The transfer slider  50  is moved in the traveling direction along the rails  28  of the fixed modules  20  and moved over the end of the frame  23  near the lifting and lowering device  80  and onto the lifting and lowering frame  81  of the lifting and lowering device  80 . In the linear conveyor  10 A, the transfer slider  50  is stopped at a predefined component supply position during a transfer process and operations such as supplying of components, screwing, and sealing are performed. 
     (Sliding Mechanism  60 ) 
     As illustrated in  FIG. 4 , the sliding mechanism  60  includes a shaft portion  61 , tubular portions  70  (two tubular portions  70  in this embodiment), and the fitting portion  41 . The shaft portion  61  is inserted through the tubular portions  70 . The fitting portion  41  has a recessed shape such that the end portion of the shaft portion  61  is fitted in the recessed shape. 
     The shaft portion  61  has a circular columnar bar shape elongated in the traveling direction of the transfer slider  50 . The shaft portion  61  has a fitting portion  62  in a right end portion thereof (one end portion in the elongated direction) and the fitting portion  62  is fitted in the fitting portion  41  included in a left edge portion of the first support member  40 . The fitting portion  62  is slidably fitted in the fitting portion  41 . The shaft portion  61  has a fixed portion  63  in a left end portion thereof (another end portion in the elongated direction) and the fixed portion  63  is fixed to the second support member  42  with a connection fixing portion  65 . The connection fixing portion  65  includes a fixing plate  66  and bolts BT as a screwing member for fixing the fixing plate  66  to the second support member  42  and the shaft portion  61 . The fixing plate  66  includes screw holes and the bolts BT are inserted through the screw holes and screwed up and the second support member  42  and the shaft portion  61  are fixed to each other (the relative movement of the second support member  42  and the shaft portion  61  is restricted). 
     The shaft portion  61  has an insertion portion  68  between the two end portions thereof (between the fixed portion  63  and the fitting portion  62 ). The insertion portion  68  is inserted in the tubular portions  70  that extend below the frame  23  so as to slide along the tubular portions  70 . The tubular portions  70  are fixed to each of the mount portions  27  of the frame  23  and are arranged in the right-left direction between the first support member  40  and the second support member  42 . As illustrated in  FIG. 5 , each of the tubular portions  70  includes a holder portion  71  made of metal such as aluminum alloy and linear bushings  72  that are provided in two end portions of the holder portion  71 , respectively, with respect to an axial direction. As illustrated in  FIG. 6 , the holder portion  71  is fixed to the mount portion  27  of the frame  23  with a fixing member  74  such as a bolt. The linear bushings  72  are made of metal or synthetic resin and prevent the wearing between the insertion portion  68  and the tubular portion  70 . The linear bushings  72  may include balls to move the shaft portion  61  smoothly. 
     (Two Lifting and Lowering Devices  80 ) 
     As illustrated in  FIG. 2 , the two lifting and lowering devices  80  are arranged in two end portions of a group of the fixed modules  20 , respectively, and the two lifting and lowering devices  80  and the fixed modules  20  are arranged in a line. As illustrated in  FIG. 4 , each of the lifting and lowering devices  80  includes the frame  23  (and the rails  28 ) that are disposed continuously from the frame  23  (and the rails  28 ) of the fixed module  20 . As illustrated in  FIG. 3 , the lifting and lowering device  80  lifts or lowers the transfer slider  50  that has reached the predefined position on the lifting and lowering frame  81  by the driving of the driving motor (in  FIG. 3 , the lifting and lowering movement of the transfer slider  50  and the lifting and lowering frame  81  is illustrated with two-dot chain lines). After the transfer slider  50  is lifted or lowered by the driving of the lifting and lowering device  80 , the traveling direction of the transfer slider  50  is reversed and the transfer slider  50  is transferred along the rails  28  of the fixed modules  20  on the different level. 
     (Operations and Advantageous Effects of the Present Embodiment) 
     The linear conveyor  10 A is a linear conveyor that is fixed to the base member  11 . As illustrated in  FIG. 4 , the linear conveyor  10 A includes the transfer slider  50 , the frame  23 , the first support member  40 , the second support member  42 , and the sliding mechanism  60 . The frame  23  includes the rails  28  that guide the transfer slider  50  in the traveling direction. The first support member  40  is arranged on one end side of the frame  23  in the longitudinal direction thereof and fixedly supports the frame  23  and is fixed to the base member  11 . The second support member  42  is arranged on another end side of the frame  23  in the longitudinal direction thereof and supports the frame  23  to be movable and is fixed to the base member  11 . The sliding mechanism  60  allows the relative sliding movement of the second support member  42  and the frame  23  in the longitudinal direction according to the difference in the thermal expansion and contraction amounts of the base member  11  and the frame  23 . 
     The temperature of the frame  23  and the base member  11  increases due to the heat generated when the linear conveyor  10 A starts driving. Unlike the above embodiment, if the frame  23  is fixed not only to the first support member  40  but also to the second support member  42  and the materials of the frame  23  and the base member  11  differ from each other, the frame  23  and the base member  11  are different in the coefficient of linear expansion and this creates thermal stress between the frame  23  and the base member  11  and warping may be caused in the frame  23 . Even in the configuration including the frame  23  and the base member  11  made of the same material, if the shapes of the heat generating components of circuits, the frame, or the base member differ from each other, the thermal stress is created and warping may be caused in the frame  23 . 
     In the present embodiment, the left end portion (the other end portion in the longitudinal direction) of the frame  23  is not fixed to the second support member  42 . If the difference in the thermal expansion and contraction amounts is created between the base member  11  and the frame  23 , the thermally expanded length of the frame  23  may be greater than that of the mounting plate  15  of the base member  11  due to the different materials as illustrated in  FIG. 7 . Even in such a configuration, as illustrated in  FIG. 8 , the end A 2  of the frame  23  can move closer to the lifting and lowering device  80  than the end A 3  of the mounting plate  15  of the base member  11  (and of the second support member  42 ) does. This suppresses occurrence of warping or deflection of the frame  23  (A 1  in  FIG. 8  represents the end of the frame  23  before the thermal expansion and contraction). The sliding mechanism  60  allows relative sliding movement of the second support member  42  and the frame  23  in the longitudinal direction according to the difference in the thermal expansion and contraction amounts of the base member  11  and the frame  23 . With such a configuration, the position displacement of the frame  23  in a direction different from the longitudinal direction is less likely to be caused in the end portion thereof that is not fixed and near the second support member  42 . Accordingly, the transfer slider  50  can smoothly travel between the adjacent rails  28 . 
     The sliding mechanism  60  is fixed to the second support member  42  (one of the first support member  40  and the second support member  42 ) and includes the fitting portion  62  that is slidably fitted to the first support member  40  (another one of the first support member  40  and the second support member  42 ). 
     According to such a configuration, since the fitting portion  62  is slidably fitted to the first support member  40  (the other one of the first support member  40  and the second support member  42 ), occurrence of warping and deflection of the frame  23  can be suppressed and the traveling between the adjacent rails  28  can be performed smoothly with a simple structure. The sliding mechanism  60  is not necessarily fixed directly to the base member  11 . Therefore, the base member  11  need not have a configuration (such as screw holes) for fixing the sliding mechanism  60  and the sliding mechanism  60  can be installed in the existing configuration easily. 
     The sliding mechanism  60  includes the tubular portions  70  that have a tubular shape and fixed to the frame  23  (one of the frame  23  and the second support member  42 ) and the insertion portion  68  that is fixed to the second support member  42  (the other one of the frame  23  and the second support member  42 ) is inserted in the tubular portions  70  to slide along the tubular portions  70 . 
     According to such a configuration, if the difference is created in the thermal expansion and contraction amounts of the base member  11  and the frame  23 , the position displacement in the direction different from the longitudinal direction is suppressed directly by the frame  23  (not via the first support member  40 ). 
     The tubular portion  70  includes the linear bushings  72  that slide with respect to the insertion portion  68  and the holder portion  71  that holds the linear bushings  72 . 
     According to such a configuration, the wearing between the inner surface of the tubular portion  70  and the outer surface of the insertion portion  68  can be suppressed. 
     The linear conveyor includes the fixed modules  20  and the lifting and lowering devices  80 . The fixed module  20  includes the frame  23 , the first support member  40 , the second support member  42 , and the sliding mechanism  60 . The lifting and lowering device  80  includes the lifting and lowering frame  81  including the lifting and lowering rails  81 A. The lifting and lowering rails  81 A are linearly arranged next to the respective rails  28  of the frame  23  of the fixed module  20 . The lifting and lowering device  80  lifts and lowers the transfer slider  50 . 
     According to such a configuration, the transfer slider  50  is lifted or lowered by the lifting and lowering device  80 . Therefore, in the configuration that requires position accuracy between the rails  28  and  81 A for smooth travel between the rails  28  and  81 A, problems are less likely to be caused in traveling between the rails  28  and  81 A. 
     Second Embodiment 
     Next, a second embodiment will be described with reference to  FIGS. 9 to 12 . A linear conveyor  90  of the second embodiment includes a sliding mechanism  91  instead of the sliding mechanism  60  of the first embodiment. The sliding mechanism  91  includes auxiliary rails  92  and auxiliary sliders  93 . In the following description, the components same as those of the first embodiment are represented by the same symbols and will not be described. 
     As illustrated in  FIGS. 9 and 10 , the sliding mechanism  91  is arranged near the second support member  42  and between the first support member  40  and the second support member  42  on the base member  11 . The sliding mechanism  91  includes two auxiliary rails  92  extending in the right-left direction (the traveling direction). The auxiliary rails  92  are fixed to the mounting plate  15  of the base member  11  with the fixing members  44  such as bolts. The auxiliary sliders  93  are fixed to the respective mount portions  27  of the frame  23  via a connection fixing portion  95 . As illustrated in  FIG. 10 , the connection fixing portion  95  includes a fixing plate  96  and bolts BT with which the fixing plate  96  is fixed to the mount portion  27  and the auxiliary slider  93 . The fixing plate  96  includes screw holes and the bolts BT are inserted in the respective screw holes and screwed up such that the auxiliary slider  93  is fixed to the mount portion  27  while having the fixing plate  96  therebetween. The auxiliary rails  92  and the auxiliary sliders  93  have lengths so as to move relatively each other to absorb the difference in the thermal expansion and contraction amounts of the frame  23  and the base member  11 . In the present embodiment, the length of the auxiliary sliders  93  in the right-left direction is smaller than the length of the auxiliary rails  92  in the right-left direction. 
     In the second embodiment, if the thermally expanded length of the frame  23  is greater than that of the mounting plate  15  of the base member  11  due to the difference in the materials thereof as illustrated in  FIG. 11 , the end A 2  of the frame  23  is moved closer to the lifting and lowering device  80  than the end A 3  of the mounting plate  15  of the base member  11  (and of the second support member  42 ) does as illustrated in  FIG. 12 . This suppresses the warping and deflection of the frame  23 . Since the auxiliary rails  92  and the auxiliary sliders  93  allow relative movement of the second support member  42  and the frame  23  in the longitudinal direction according to the difference in the thermal expansion and contraction amounts of the base member  11  and the frame  23 , the position displacement of the frame  23  in the direction different from the longitudinal direction is suppressed at the portion of the frame  23  that is near the second support member  42  and not fixed. Accordingly, the problems are less likely to be caused when the transfer slider  50  travels between the adjacent rails  28 . 
     The sliding mechanism  91  includes the auxiliary rails  92  that are fixed to the base member  11  (one of the base member  11  and the frame  23 ) and the auxiliary sliders  93  that are fixed to the frame  23  (another one of the base member  11  and the frame  23 ) and can slide with respect to the auxiliary rails  92 . 
     According to such a configuration, the first support member  40  or the second support member  42  is not necessarily processed to provide the sliding mechanism  91 . Therefore, the first support member  40  or the second support member  42  need not be prepared as an exclusive component and this reduces a manufacturing cost. The sliding mechanism  91  can be additionally installed in the existing configuration easily. 
     Third Embodiment 
     Next, a third embodiment will be described with reference to  FIGS. 13 to 15 . A linear conveyor  100  of the third embodiment includes a sliding mechanism  101  between the frame  23  and a second support member  104  unlike the sliding mechanism  91  of the second embodiment. In the following description, the components same as those of the above embodiment are represented by the same symbols and will not be described. 
     As illustrated in  FIG. 13 , the sliding mechanism  101  includes the auxiliary rails  92  that are fixed on the base member  11  and the auxiliary sliders  93  that are fixed on an end portion side of the frame  23 . The second support member  104  that supports the weight on the end portion side of the frame  23  is made of metal such as aluminum alloy and has a small height dimension. The auxiliary rails  92  are fixed on the second support member  104 . The second support member  104  is fixed to the mounting plate  15  of the base member  11  with fixing members  105  such as bolts. A circuit unit  108  is arranged below the left end portion of the frame  23 . The circuit unit  108  includes a circuit provided on a board and a case having the circuit therein. The circuit unit  108  is fixed to the frame  23  with fixing members  106  such as bolts. A spacer unit  103  is fixed to the circuit unit  108  with fixing members  107  such as bolts and is disposed below the circuit unit  108 . The spacer unit  103  and the auxiliary slider  93  are fixed to each other via the fixing members  105  such as bolts. The auxiliary slider  93 , the spacer unit  103 , and the circuit unit  108  support the frame  23  while being able to slide on the second support member  104  and the auxiliary rails  92  in the longitudinal direction of the frame  23 . 
     According to the third embodiment, if the thermally expanded length of the frame  23  is greater than that of the mounting plate  15  of the base member  11  due to the difference in the materials thereof as illustrated in  FIG. 14 , the end A 2  of the frame  23  is moved closer to the lifting and lowering device  80  than the end A 3  of the mounting plate  15  of the base member  11  does as illustrated in  FIG. 15 . This suppresses the warping and deflection of the frame  23 . Furthermore, the sliding mechanism  101  includes the auxiliary rails  92  that are fixed to the second support member  104  (one of the second support member  104  and the frame  23 ) and is fixed to the frame  23  (other one of the second support member  42  and the frame  23 ). According to such a configuration, the frame  23  is not fixed to the second support member  42  by including the auxiliary rails  92  and the auxiliary slider  93 , and this simplifies the configuration. 
     Other Embodiments 
     The technology described herein is not limited to the embodiments described in the above description and the drawings. The following embodiments may be included in the technical scope of the technology described herein, for example. 
     (1) In the first embodiment, the shaft portion  61  that is fixed to the second support member  42  is inserted in the tubular portion of the frame  23  and is fitted in the fitting portion  41  of the first support member  40 . However, the tubular portion may be fixed to the second support member  42  instead of the shaft portion  61  and the frame  23  or the first support member  40  may include a shaft portion that is to be inserted in the tubular portion  70 . 
     (2) In each of the second embodiment and the third embodiment, the auxiliary rails  92  are fixed to the base member  11  and the auxiliary sliders  93  are fixed to the frame  23  side. However, the auxiliary rails  92  may be fixed to the frame  23  side and the auxiliary sliders  93  may be fixed to the base member  11  side. 
     (3) The tubular portion  70  includes the linear bushings  72  in addition to the holder portion  71  but may not include the linear bushings  72 . 
     (4) The dimension of the gap G between the frame  23  of the fixed module and the lifting and lowering frame  81  of the lifting and lowering device  80  is changed by the thermal expansion or contraction of the frame  23 ; however, the device may be configured as follows. A dimension of a gap between (the frames  23  of) the adjacent fixed modules may be changed according to the thermal expansion and contraction of the frame  23  and at least one of the adjacent fixed modules may include the sliding mechanism  60 . 
     (5) Two lifting and lowering devices are included; however, the lifting and lowering devices may not be included. For example, the linear conveyor may be configured such that the transfer slider  50  travels only linearly. The fixed modules  20  may be arranged on a same level and a moving device that moves between the fixed modules  20  may be included. The number of fixed modules  20  is not limited to the one in the above embodiments and a linear conveyor may include any number of fixed modules  20 . 
     EXPLANATION OF SYMBOLS 
       10 ,  90 ,  100 : linear conveyor,  11 : base member,  20 : fixed module,  23 : frame,  28 : rail,  30 : stator,  40 : first support member,  41 : fitting portion,  42 ,  104 : second support member,  50 : transfer slider,  56 : rail guide,  60 ,  91 ,  101 : sliding mechanism,  61 : shaft portion,  62 : fitting portion,  68 : insertion portion,  70 : tubular portion,  71 : holder portion,  72 : linear bushing,  80 : lifting and lowering device,  81 : lifting and lowering frame,  81 A: lifting and lowering rail,  92 : auxiliary rail,  93 : auxiliary slider, G: gap