Patent Publication Number: US-2011073591-A1

Title: Guide Chip Structure for High-Frequency Induction Heating Coil

Description:
TECHNICAL FIELD 
     The present invention relates to a structure of a plurality of guide chips for high frequency induction heating coil which are respectively attached between a pair of side plates for supporting a semi-open saddle type high frequency induction heating coil, and which, when a journal portion or a pin portion of a crankshaft is subjected to high frequency induction heating by the semi-open saddle type high frequency induction heating coil, are used for positioning the center of the journal portion or the pin portion with respect to the semi-open saddle type high frequency induction heating coil, and used for positioning the semi-open saddle type high frequency induction heating coil in the width direction of the journal portion or the pin portion between mutually adjacent counterweight portions of the crankshaft. More particularly, the present invention relates to a structure of a plurality of guide chips for high frequency induction heating coil in which the structure enables the non-hardened area of the hardened case formed in the journal portion or the pin portion to fully satisfy the range of the specification. 
     BACKGROUND ART 
     As shown in  FIG. 9 , a crankshaft  1  which is an object to be heated is configured by a journal portion  2  serving as a central shaft, counterweight portions  3  arranged between the journal portions  2  adjacent to each other, and a pin portion  4  provided between the counterweight portions  3  facing each other, and the like. The journal portion  2  and the pin portion  4  are subjected to high frequency induction heating so as to be hardened. As the hardening methods, there are flat hardening and filet R hardening. In any of the methods, a hardened case needs to be correctly formed in the journal portion  2  or the pin portion  4 . Note that as a high frequency induction heating apparatus for applying high frequency induction heating to the journal portion  2  or the pin portion  4 , there is conventionally adopted, for example, an apparatus as shown in FIG. 1 of Japanese Patent Laid-Open No. 2002-226919 (patent document 1). 
     The high frequency induction heating apparatus as described in Japanese Patent Laid-Open No. 2002-226919 is configured as shown in FIG. 1 in Japanese Patent Laid-Open No. 2002-226919.  FIG. 10  shows a high frequency induction heating apparatus  6  which is similar to the apparatus shown in FIG. 1 in Japanese Patent Laid-Open No. 2002-226919, and which uses a semi-open saddle type high frequency induction heating coil  5 . 
     As shown in  FIG. 10 , the high frequency induction heating apparatus  6  includes a pair of side plates  7  which are connected to the apparatus main body side so as to be arranged to face each other, the semi-open saddle type high frequency induction heating coil  5  which is arranged in a lower end side opening portion of the side plate  7  so as to be supported by the side plate  7 , guide chips  8   a ,  8   b  and  8   c  for high frequency induction heating coil which are arranged at predetermined places (in the present example, three places of the upper side portion with respect to the center line of the journal portion  2  of the crankshaft  1 , and of the left and right side portions with respect to the center line of the journal portion  2 ) corresponding to the semi-open saddle type high frequency induction heating coil  5 , so as to be attached to the side plate  7 , and the like. Furthermore, in the high frequency induction heating apparatus  6 , a power supply lead conductor  9  is connected to the semi-open saddle type high frequency induction heating coil  5 , and cooling water supply means  10  for quickly cooling a heated portion of the crankshaft  1 , and the like, is provided. The guide chips  8   a ,  8   h  and  8   c  for high frequency induction heating coil are members provided so that a predetermined gap (about 0.5 mm to 3.5 mm) is secured between the journal portion  2  (or the pin portion  4 ) of the crankshaft  1  and the semi-open saddle type high frequency induction heating coil  5  at the time when the journal portion  2  (or the pin portion  4 ) is subjected to high frequency induction heating by the semi-open saddle type high frequency induction heating coil  5 . In addition, the guide chips  8   a ,  8   b  and  8   c  are configured such that the semi-open saddle type high frequency induction heating coil  5  is mounted, via the guide chips  8   a ,  8   b  and  8   c , on the journal portion  2  (or the pin portion  4 ) which is rotated about the axis line of the crankshaft  1  (the center line of the journal portion  2 ). At this time, the center of the journal portion  2  (or the pin portion  4 ) is positioned with respect to the semi-open saddle type high frequency induction heating coil  5  by abutting action of the guide chips  8   a ,  8   b  and  8   c  on the outer peripheral surface of the journal portion  2 .
     Patent document 1: Japanese Patent Application Laid-Open No. 2002-226919   

     DISCLOSURE OF THE INVENTION 
     Problems to be Solved by the Invention 
     The guide chips  8   a ,  8   b  and  8   c  for high frequency induction heating coil which are provided in the conventional high frequency induction heating apparatus  6  having the above-described structure are usually configured by components as shown in  FIG. 11(   a ) and  FIG. 11(   b ). That is, each of the guide chips  8   a ,  8   b  and  8   c  is configured by the side plates  7  and  7  which are arranged so as to face each other via a gap  11 , chips  12  and  12  which are respectively arranged in contact with the inner surfaces of the side plates  7  and  7 , a chip fixing plate  13  provided between the chips  12  and  12 , screws  14  and  14  which integrally and closely fix the side plates  7  and  7 , the chips  12  and  12 , and the chip fixing plate  13  to each other, and the like. Here, the width dimension L 1  (see  FIG. 11(   a )) between the outer surfaces of the chips  12  and  12  is fixed (cannot be changed), and hence it is necessary to make the width dimension L 1  almost equal to the width dimension L 2  or L 3  (see  FIG. 9)  of the journal portion  2  or the pin portion  4  of the crankshaft  1 . 
     However, in the case in which the width dimension L 1  is made completely equal to, for example, the width dimension L 2  of the journal portion  2 , when the guide chips  8   a ,  8   b  and  8   c  are inserted between the counterweight portions  3  and  3  on both sides of the journal portion  2  so as to be mounted on the journal portion  2 , the guide chips  8   a ,  8   b  and  8   c  are not smoothly inserted. Thus, the width dimension L 1  must be set slightly smaller than the width dimension L 2 . Furthermore, even if there are used the guide chips for high frequency induction heating coil, which have the same width dimension L 1  as the width dimension L 2  of a journal portion  2  of a crankshaft  1  of a certain type, in the case in which the same guide chips for high frequency induction heating coil are also used for a crankshaft  1  of another type which has substantially similar dimensions and in which the journal portion  2  has the same outside diameter dimension but has a width dimension slightly larger than the width dimension L 2 , a gap is generated between the counterweight portion  3  of the crankshaft  1  and the guide chip for high frequency induction heating coil. FIG.  12 ( a ) shows a state in which a gap δ is generated between the outer surface of the chip  12  and the inner surface of the counterweight portion  3 , and shows a case in which the gap δ is generated because the width dimension L 1  of the guide chip  8   a  (and  8   b ,  8   c ) for high frequency induction heating coil is smaller than the width dimension L 2  of the journal portion  2 . In this case, the semi-open saddle type high frequency induction heating coil  5  is arranged so as to face the outer peripheral surface of the journal portion  2  at a position shifted from the width-direction central position of the journal portion  2  similarly to the guide chip  8   a  (and  8   b ,  8   c ) for high frequency induction heating coil. 
     When the outer peripheral surface of the journal portion  2  is subjected to high frequency induction heating for flat hardening while the crankshaft  1  is rotated about the axis line thereof (the center line of the journal portion  2 ) in the state in which the gap δ exists as described above, a hardened case S 1  is formed at a position shifted from the center in the width direction of the journal portion  2  (for example, at a position shifted to the right side) as shown in  FIG. 12(   b ). This causes a problem in that the dimensions α and β between each end portion of the hardened case S 1  and the inner surfaces of the counterweight portion  3  are different from each other. The dimensions α and β are referred to as “non-hardened areas”, and a specification is specified for the dimension. However, there arises a case in which the dimensions α and β do not satisfy the specification. 
     Furthermore, in the case in which the outer peripheral surface of the journal portion  2  is subjected to high frequency induction heating for fillet R hardening while the crankshaft  1  is rotated about the axis line thereof, when there is the gap δ between the guide chip  8   a  (and  8   b ,  8   c ) for high frequency induction heating coil and the counterweight portion  3  of the crankshaft  1  as shown in  FIG. 12(   c ), the guide chip  8   a  (and  8   b ,  8   c ) for high frequency induction heating coil is not correctly positioned in the width direction of the journal portion  2 . Therefore, the semi-open saddle type high frequency induction heating coil  5  is also not correctly positioned, so as to thereby cause a difference between case depths t 1  and t 2  at corner portions of a hardened case S 2  formed by the fillet R hardening, as shown in  FIG. 12(   d ). As a result, there arises a case in which the values of the case depths t 1  and t 2  do not satisfy the specification. 
     The present invention has been made in order to solve the above-described problem. An object of the present invention is to provide the structure of the guide chips for high frequency induction heating coil, in which structure the guide chips for high frequency induction heating coil can always be correctly positioned in the width direction of the journal portion or the pin portion of the crankshaft, and hence the semi-open saddle type high frequency induction heating coil  5  can always be correctly positioned in the above-described width direction, and in which structure the non-hardened area in the case of flat hardening, and the case depth at the corner portion of the hardened case in the case of fillet R hardening can satisfy the specifications, and thereby the precise hardening can be performed. 
     Means for Solving the Problems 
     In order to achieve the above-described object, according to the present invention, there is provided a structure of a plurality of guide chips for high frequency induction heating coil, which are respectively attached between a pair of side plates for supporting a semi-open saddle type high frequency induction heating coil, which when a journal portion or a pin portion of a crankshaft is subjected to high frequency induction heating by the semi-open saddle type high frequency induction heating coil, are used for positioning the center of the journal portion or the pin portion with respect to the semi-open saddle type high frequency induction heating coil, and which are used for positioning the semi-open saddle type high frequency induction heating coil in the width direction of the journal portion or the pin portion between the mutually adjacent counterweight portions of the crankshaft, the structure being characterized in that the guide chip for high frequency induction heating coil includes: a pair of flexible bodies which have a spring function and are respectively provided in the pair of side plates; a pair of chips which are respectively arranged and fixed in the inside of the pair of flexible bodies facing each other; and a pair of chip fixing plates which are respectively arranged and fixed in the inside of the pair of chips, and characterized by being configured such that, in a free state in which the guide chip for high frequency induction heating coil is not inserted between the mutually adjacent counterweight portions, a gap exists between the inner surfaces of the pair of chip fixing plates facing each other and thereby the width dimension between the outer surfaces of the pair of chips facing each other is set larger than the width dimension of the journal portion or the pin portion, and such that when the guide chip for high frequency induction heating coil is inserted between the mutually adjacent counterweight portions, the gap between the inner surfaces of the pair of chip fixing plates is reduced or eliminated by the spring function of the pair of flexible bodies. 
     Furthermore, according to the present invention, it is configured such that the flexible body is integrally provided to the side plate by forming, in the side plate, a pair of slits that are arranged at a distance so as to face each other and that are extended to an opening portion of the side plate in which portion the journal portion or the pin portion is inserted and arranged. 
     Furthermore, according to the present invention, it is configured such that the guide chips for high frequency induction heating coil are arranged at three places of the upper side and the left and right sides with respect to the center line of the journal portion or the pin portion, and such that the flexible body is provided at all or at least one of the three places in which the three guide chips for high frequency induction heating coil are arranged. 
     ADVANTAGES OF THE INVENTION 
     In the first aspect of the present invention, the guide chip for high frequency induction heating coil includes: a pair of flexible bodies which have a spring function and are respectively provided in a pair of side plates; a pair of chips which are respectively arranged and fixed in the inside of the pair of flexible bodies facing each other; and a pair of chip fixing, plates which are respectively arranged and fixed in the inside of the pair of chips, and is configured such that, in a free state in which the guide chip for high frequency induction heating coil is not inserted between the mutually adjacent counterweight portions of the crankshaft, a gap exists between the inner surfaces of the pair of chip fixing plates facing each other and thereby the width dimension between the outer surfaces of the pair of chips facing each other is set larger than the width dimension of the journal portion or the pin portion, and such that when the guide chip for high frequency induction heating coil is inserted between the mutually adjacent counterweight portions, the gap between the inner surfaces of the pair of chip fixing plates is reduced or eliminated by the spring function of the pair of flexible bodies. Thus, with the structure of the guide chip for high frequency induction heating coil according to the present invention, it is possible to obtain the following operation effects. That is, the guide chip for high frequency induction heating coil is configured as a flexible member (whose width dimension can be changed). Thus, when the guide chip for high frequency induction heating coil is inserted between the counterweight portions adjacent to each other in the width direction of the journal portion or the pin portion, the guide chip for high frequency induction heating coil, which has, in the free state, the width dimension larger than the width dimension between the mutually adjacent counterweight portions, is elastically deformed so that the gap between the inner surfaces of the pair of chip fixing plates is reduced by the spring function of the flexible bodies of the side plates. As a result, the pair of chips are inserted and arranged between the mutually adjacent counterweight portions, so as to be brought into press contact with the respective counterweight portions. Thereby, the guide chip for high frequency induction heating coil can always be correctly positioned in the width direction of the journal portion or the pin portion between the mutually adjacent counterweight portions. Thus, the semi-open saddle type high frequency induction heating coil can always be correctly positioned in the width direction of the journal portion or the pin portion. Thereby, the non-hardened area can be stably suppressed to be within the specification. Furthermore, by suitably setting the flexible range of the above-described flexible body, the same guide chip for high frequency induction heating coil can also be used for a crankshaft in which the journal portion or the pin portion has the same outside diameter dimension but has a slightly different width dimension. 
     Furthermore, in the second aspect of the present invention, it is configured such that the flexible body is integrally provided to the side plate by forming, in the side plate, a pair of slits which are arranged at a distance so as to face each other and which are extended to the opening portion of the side plate in which portion the journal portion or the pin portion is inserted. Thus, it is not necessary to provide a flexible body configured by a member which is separate from the side plate. Therefore, it is possible to facilitate the manufacturing of the high frequency induction heating apparatus. 
     Furthermore, in the third aspect of the present invention, it is configured such that the guide chips for high frequency induction heating coil are arranged at three places of the upper side and the left and right sides with respect to the center line of the journal portion or the pin portion, and such that the flexible body is provided at all or at least one of the three places in which the three guide chips for high frequency induction heating coil are arranged. Hence, it is obvious that, when all the guide chips arranged at the three places are made flexible, the guide chips for high frequency induction heating coil and thus the semi-open saddle type high frequency induction heating coil can be surely positioned in the width direction of the journal portion or the pin portion. Furthermore, even when at least one of the guide chips arranged at the three places are made flexible, the above-described positioning in the width direction can be performed more correctly than before, so that the non-hardened area can be suppressed to be within the specification. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a front view showing a high frequency induction heating apparatus having a structure of guide chips for a high frequency induction heating coil according to an embodiment of the present invention; 
         FIG. 2  is a front view showing a side plate of the high frequency induction heating apparatus shown in  FIG. 1 , in a state in which the guide chips for high frequency induction heating coil are attached to the side plate; 
         FIG. 3  shows a structure of the guide chip for high frequency induction heating coil according to the present invention; 
         FIG. 3(   a ) is a sectional view of the guide chip for high frequency induction heating coil taken along the line A-A in  FIG. 3(   b ); 
         FIG. 3(   b ) is a side view showing a place at which the guide chip for high frequency induction heating coil is attached to the side plate; 
         FIG. 4  shows a relationship of the guide chip for high frequency induction heating coil with a journal portion and a counterweight portion of a crankshaft; 
         FIG. 4(   a ) is a sectional view showing the guide chip for high frequency induction heating coil in a free state; 
         FIG. 4(   b ) is a sectional view showing a state in which the guide chip for high frequency induction heating coil is inserted between the mutually adjacent counterweight portions; 
         FIG. 5  is a sectional view showing a state in which a hardened case is formed in a portion without an oil hole in the journal portion by using the guide chip for high frequency induction heating coil according to the present embodiment; 
         FIG. 6  is a sectional view showing a state in which a hardened case is formed in a portion with an oil hole in the journal portion by using the guide chip for high frequency induction heating coil; 
         FIG. 7  is a graph showing non-hardened areas formed in the portion without the oil hole in the journal portions by using the guide chip for high frequency induction heating coil according to the present embodiment and by using a conventional guide chip for high frequency induction heating coil; 
         FIG. 8  is a graph showing non-hardened areas formed in the portion with the oil hole in the journal portions by using the guide chips for high frequency induction heating coil according to the present embodiment; 
         FIG. 9  is a side view of a crankshaft; 
         FIG. 10  is a side view showing a main portion of a high frequency induction heating apparatus having the conventionally configured guide chips for high frequency induction heating coil; 
         FIG. 11  shows a structure of the conventional guide chip for high frequency induction heating coil; 
         FIG. 11(   a ) is a sectional view of the conventional guide chip for high frequency induction heating coil taken along the line B-B in  FIG. 11(   b ); 
         FIG. 11(   b ) is a front view of the conventional guide chip for high frequency induction heating coil; 
         FIG. 12  is a sectional view showing a hardening method of the journal portion of the crankshaft, using the conventional guide chip for high frequency induction heating coil; 
         FIG. 12(   a ) is a sectional view showing a state in flat hardening; 
         FIG. 12(   b ) is a sectional view showing a hardened case formed in the journal portion by the flat hardening; 
         FIG. 12(   c ) is a sectional view showing a state in fillet R hardening; and 
         FIG. 12(   d ) is a sectional view showing a hardened case formed in the journal portion by the fillet R hardening. 
     
    
    
     DESCRIPTION OF SYMBOLS 
     
         
           1  Crankshaft 
           2  Journal portion 
           3  Counterweight portion 
           4  Pin portion 
           5  Semi-open saddle type high frequency induction heating coil 
           7  Side plate 
           20  High frequency induction heating apparatus 
           21   a ,  21   b ,  21   c  Guide chip for high frequency induction heating coil 
           22  Semicircular arc-shaped opening portion 
           23  Slit 
           24   a ,  24   b ,  24   c  Flexible body 
           25 ,  26  Slit 
           29   a  Chip 
           30   a  Chip fixing plate 
           31   a  Screw 
           32  Gap 
       
    
     BEST MODE FOR CARRYING OUT THE INVENTION 
     In the following, there will be described a structure of guide chips for a high frequency induction heating coil according to an embodiment of the present invention with reference to  FIG. 1  to  FIG. 8 . Note that in  FIG. 1  to  FIG. 8 , the same portions as those in  FIG. 9  to  FIG. 12  are denoted by the same reference numerals and characters, and the repeated explanation thereof is omitted. 
       FIG. 1  shows a high frequency induction heating apparatus  20  having a structure of guide chips for a high frequency induction heating coil according to an embodiment of the present invention. The high frequency induction heating apparatus  20  is configured to apply high frequency induction heating to a journal portion  2  of a crankshaft  1 . As shown in  FIG. 1 , the high frequency induction heating apparatus  20  includes a pair of side plates  7  which are respectively connected to the side of a transformer (not shown) and which are arranged so as to face each other, a semi-open saddle type high frequency induction heating coil  5  which is arranged at a lower end side opening portion of the side plate  7  so as to be supported by side plate  7 , a power supply lead conductor  9  which supplies high frequency power to the semi-open saddle type high frequency induction heating coil  5  from a power source (not shown), and three guide chips  21   a ,  21   b  and  21   c  for high frequency induction heating coil which are attached at predetermined positions of the side plate  7  in correspondence with the semi-open saddle type high frequency induction heating coil  5  (in the present embodiment, at three places of the upper side portion with respect to the center line of the journal portion  2  of the crankshaft  1 , and of the left and right side portions with respect to the center line of the journal portion  2 ). Furthermore, the high frequency induction heating apparatus  20  is provided with cooling water supply means  10  for spraying cooling water for hardening treatment to the journal portion  2  which is subjected to high frequency induction heating by the semi-open saddle type high frequency induction heating coil  5 . Note that  FIG. 2  is a front view of the side plate  7  for representing the structure of the three guide chips  21   a ,  21   b  and  21   c  for high frequency induction heating coil, which are main components of the present embodiment. 
     The three guide chips  21   a ,  21   b  and  21   c  for high frequency induction heating coil are respectively attached between the pair of side plates  7  and  7  for supporting the semi-open saddle type high frequency induction heating coil  5 . The three guide chips  21   a ,  21   b  and  21   c  are arranged so as to be brought into contact with the upside portion and the left and right side portions of the journal portion  2  of the crankshaft  1  which journal portion is driven and rotated about the center line of the journal portion  2  by a rotary drive mechanism (not shown), in order to secure a predetermined gap between the journal portion  2  and the semi-open saddle type high frequency induction heating coils  5  at the time when the journal portion  2  is subjected to high frequency induction heating by the semi-open saddle type high frequency induction heating coil  5 . Specifically, as shown in  FIG. 1  and  FIG. 2 , one guide chip  21   a  among the three guide chips  21   a ,  21   b  and  21   c  for high frequency induction heating coil is arranged at the upper side portion with respect to the center line of the journal portion  2  of the crankshaft  1 , while the other two guide chips  21   b  and  21   c  for high frequency induction heating coil are arranged at the left and right side portions with respect to the center line of the journal portion  2 . Furthermore, when the three guide chips  21   a ,  21   b  and  21   c  for high frequency induction heating coil are brought into contact with the outer peripheral surface of the journal portion  2 , the center of the journal portion  2  is positioned with respect to the semi-open saddle type high frequency induction heating coil  5 . 
       FIGS. 3(   a ) and  3 ( b ) show a detailed structure of the guide chip  21   a  for high frequency induction heating coil, which is used in the high frequency induction heating apparatus  20 .  FIG. 3(   b ) is a side view of the guide chip  21   a  for high frequency induction heating coil.  FIG. 3(   a ) is a sectional view taken along the line A-A in  FIG. 3(   b ). Note that the arrangement positions and directions of the other guide chips  21   b  and  21   c  for high frequency induction heating coil are different from those of the guide chip  21   a  for high frequency induction heating coil, but the structure of the guide chips  21   b  and  21   c  for high frequency induction heating coil is substantially the same as the structure of the guide chip  21   a  for high frequency induction heating coil. Thus, the description of the structure of the guide chips  21   b  and  21   c  is omitted. 
     As shown in  FIG. 2 , a semicircular arc-shaped opening portion  22 , in which the journal portion  2  of the crankshaft  1  is inserted and arranged, is foamed in the lower portion of the side plates  7  and  7 . The distal end portions of the guide chips  21   a ,  21   b  and  21   c  for high frequency induction heating coil, which are configured as shown in  FIGS. 3(   a ) and ( b ), are arranged so as to project into the above-described semicircular arc-shaped opening portion  22 , at the upper side portion and the left and right side portions of the semicircular arc-shaped opening portion  22  of the side plates  7  and  7  (that is, at the upper portion with respect to the center line of the journal portion  2  and at the left and right portions with respect to the center line). More specifically, at the upper side portion of the semicircular arc-shaped opening portion  22  of the side plates  7  and  7 , there are respectively formed a pair of slits  23  and  23  which are extended upward from the semicircular arc-shaped opening portion  22  so as to be in parallel with each other, so that the portion between the pair of slits  23  and  23  (a cantilever supported plate-shaped body having a spring function) is provided as a flexible body  24   a . At the left and right side portions of the semicircular arc-shaped opening portion  22  of the side plates  7  and  7 , there are formed a slit  25  and a slit  26  which are respectively extended from the semicircular arc-shaped opening portion  22  to the left and right sides thereof, and the side plate portions respectively adjacent to the slits  25  and  26  are provided as flexible bodies  24   b  and  24   c . Furthermore, the guide chip  21   a  for high frequency induction heating coil is attached between the flexible bodies  24   a  and  24   a  of the side plates  7  and  7 , and the guide chips  21   b  and  21   c  for high frequency induction heating coil are respectively attached between the flexible bodies  24   b  and  24   b  of the side plates  7  and  7 , and between the flexible bodies  24   c  and  24   c  of the side plates  7  and  7 . Therefore, in the present embodiment all of the three guide chips  21   a ,  21   b  and  21   c  for high frequency induction heating coil are configured so as to be flexible. Note that reference numerals  27  and  27  in  FIG. 1  denote auxiliary side plates, and one slit  25  and one slit  26  are provided to each of the side plates  7  and  7  (see  FIG. 2) . However, the present invention is not limited to this configuration, and as in the case of the above-described slits  23  and  23 , it may also be configured such that two mutually parallel slits are provided to the side plates  7  and  7  so as to sandwich each of the flexible bodies  24   b  and  24   c.    
     On the other hand, as shown in  FIG. 1  to  FIG. 4 , the guide chip  21   a  for a high frequency induction heating coil comprises the pair of mutually facing flexible bodies (flexible plates)  24   a  and  24   a  which are made flexible by the slits  23  and  23 , chips  29   a  and  29   a  which are respectively fixed in close contact with the inner surfaces of the flexible bodies  24   a  and  24   a , and the distal end sides of which are expanded from the flexible bodies  24   a  and  24   a  and arranged to project from the outer surface of the flexible bodies  24   a  and  24   a , and chip fixing plates  30   a  and  30   a  which are respectively fixed in close contact with the inner surface of the chips  29   a  and  29   a . Also, each of the fixing of the flexible bodies  24   a  and  24   a , the fixing of the chips  29   a  and  29   a , and the fixing of the chip fixing plates  30   a  and  30   a  is separately performed by each pair of screws  31   a  and  31   a  at positions facing each other. Note that the side plate  7  and the flexible body  24   a  are made of a copper alloy for a spring (phosphor bronze, beryllium copper, or the like, in the present embodiment). The chip fixing plate  30   a  is mainly made of a brass material, and the chip  29   a  is made of ceramic. However, the present invention is not limited to these. 
     Furthermore, as shown in  FIG. 3(   a ), in the guide chip  21   a  for a high frequency induction heating coil, a gap  32  is formed between the inner surfaces of the chip fixing plates  30   a  and  30   a  in a free state in which the guide chip  21   a  is not inserted between the adjacent counterweight portions  3  and  3 . The flexible body  24   a  is made flexible in the direction of reducing the gap  32  by using, as a fulcrum, a position indicated by reference character P in  FIGS. 3(   a ) and  3 ( b ). Thus, the flexible bodies  24   a  and  24   a , and also the chips  29   a  and  29   a  and the chip fixing plates  30   a  and  30   a  which are respectively separately fixed to the flexible bodies  24   a  and  24   a  with the screws  31   a  and  31   a , are configured so as to be flexible by using, as a fulcrum, the position indicated by reference character P, and configured to be elastically deformed by the elasticity of the flexible bodies  24   a  and  24   a . Note that the width dimension W 1  (see  FIG. 3(   a ) and  FIG. 4(   a )) between the external surfaces of the chips  29   a  and  29   a  is set to become larger than the width dimension L 2  (see  FIG. 4(   a ),  FIG. 4(   b ) and  FIG. 9)  of the journal portion  2  of the crankshaft  1  at the time when the guide chip  21   a  for high frequency induction heating coil is in the free state as shown in  FIG. 3(   a ). In this case, when the width of the gap  32  in the free state is set as W 2  (see  FIG. 3(   a ) and  FIG. 4(   a )), the width W 2  is set to satisfy the formula: (W 1 −L 2 )≦W 2 . 
     On the other hand, the structure of the guide chips for a high frequency induction heating coil, which are used when applying high frequency induction heating to the pin portion  4  of the crankshaft  1 , is also the same as the above-described structure of the guide chip  21   a  for a high frequency induction heating coil, and hence the description thereof is omitted. Of course, for the pin portion  4  of the crankshaft  1 , the width dimension (not shown) between the outer surfaces of a pair of chips of the guide chip for high frequency induction heating coil, is set larger than the width dimension L 3  (see  FIG. 9 ) between the counterweight portions  3  and  3  on both sides of the pin portion  4 . 
     Next, there will be described an operation at the time when the journal portion  2  of the crankshaft  1  is subjected to high frequency-induction heating by the high frequency induction heating apparatus  20  including the guide chips  21   a ,  21   b  and  21   c  for high frequency induction heating coil, so as to be hardened. First, in order to apply high frequency induction heating to the journal portion  2  of the crankshaft  1 , the high frequency induction heating apparatus  20  is moved downward by a lifting mechanism (not shown) so that the journal portion  2  is arranged in the semicircular arc-shaped opening portion  22  of the side plate  7 . Thereby, the distal end portions of the guide chips  21   a ,  21   b  and  21   c  for high frequency induction heating coil (for example, distal end portions of the pair of chips  29   a  and  29   a ) are inserted between the counterweight portions  3  and  3  of the crankshaft  1 , so as to be brought into contact with the outer peripheral surface of the journal portion  2 . As described above, the width dimension W 1  of the guide chips  21   a ,  21   b  and  21   c  for high frequency induction heating coil in the free state is set larger than the width dimension L 2  between the counterweight portions  3  and  3  of the journal portion  2  (W 1 &gt;L 2 ) (see  FIG. 4(   a )), and hence, at this time, the flexible bodies  24   a  and  24   a , and the like, are elastically deformed by using, as a fulcrum, the position indicated by reference character P (see  FIG. 3(   a ) and  FIG. 3(   b )). Thereby, the width of the gap  32  in each of the guide chips  21   a ,  21   b  and  21   c  is reduced to be less than the width W 2  of the gap  32  in the free state, so as to become a width W 3 . In this case, the flexible body  24   a  is elastically deformed to reduce the gap  32 , and hence each of the pairs of the chips  29   a  and  29   a , and the like, of the guide chips  21   a ,  21   b  and  21   c  for high frequency induction heating coil are brought into press contact with the inner surfaces of the counterweight portions  3  and  3  on both sides of the journal portion  2  by the elastic restoring force (elastic force in the direction of increasing the width W 3 ) of each of the pairs of the flexible bodies  24   a  and  24   a , and the like. As a result, the guide chips  21   a ,  21   b  and  21   c  for high frequency induction heating coil and thus the semi-open saddle type high frequency induction heating coil  5  are positioned at a correct position in the width direction of the journal portion  2 . That is, the semi-open saddle type high frequency induction heating coil  5  is positioned at the center position in the width direction of the journal portion  2  between the mutually adjacent counterweight portions  3  and  3 . 
     In such a state, the crankshaft  1  is driven and rotated about the axis line thereof (the center line of the journal portion  2 ) by the rotary drive mechanism (not shown). Also, the high frequency induction heating apparatus  20 , and thus the guide chips  21   a ,  21   b  and  21   c , and the semi-open saddle type high frequency induction heating coil  5  are held by a high frequency induction heating coil following mechanism (not shown) so as to follow the rotating journal portion  2 . Thereby, the journal portion  2  is subjected to high frequency induction heating by the semi-open saddle type high frequency induction heating coil  5 . Thereafter, a hardening treatment is performed by spraying cooling water from the cooling water supply means  10  to the outer peripheral surface of the journal portion  2  which is high-frequency induction heated to a required hardening temperature, so that a hardened case is formed. 
       FIG. 5  shows a hardened case S 3  which is formed at the time when a portion  35  without an oil hole  34  in the journal portion  2  is subjected to high frequency induction heating so as to be hardened by using the guide chips  21   a ,  21   b  and  21   c  for high frequency induction heating coil.  FIG. 6  shows a hardened case S 4  which is formed at the time when a portion  37  with an oil hole  36  in the journal portion  2  is subjected to high frequency induction heating so as to be hardened by using the guide chips  21   a ,  21   b  and  21   c  for high frequency induction heating coil. Furthermore,  FIG. 7  shows non-hardened areas in the portion  35  shown in  FIG. 5 , and  FIG. 8  shows non-hardened areas in the portion  37  shown in  FIG. 6 . Note that in  FIG. 7  and  FIG. 8 , the horizontal axis represents the hardening portion, and the vertical axis represents the non-hardened area. The standard value of the non-hardened area is set in a range of 3.0 to 4.5 mm. Furthermore, in  FIG. 7  and  FIG. 8 , the □ mark represents a case in which the conventional guide chips  8   a ,  8   b  and  8   c  (see  FIG. 12 ) for high frequency induction heating coil are used, and the ⋄ mark and the ◯ mark represent cases in which the guide chips  21   a ,  21   b  and  21   c  for high frequency induction heating coil according to the present embodiment are used. In the figures, the ⋄ mark represents a case in which the flexible bodies  24   a  and  24   a  having a low spring constant (spring constant=5.9 kg/mm) are used, while the ◯ mark represents a case in which the flexible bodies  24   a  and  24   a  having a high spring constant (spring constant=7.8 kg/mm) are used. Here, the point represented by each of the □ mark, the ⋄ mark, and the ◯ mark corresponds to an average value in the non-hardened area. Also, the upper end of the straight line extended upwards from each of the marks corresponds to a maximum measured value in the non-hardened area, while the lower end of the straight line extended downwards from each of the marks corresponds to a minimum measured value in the non-hardened area. On the other hand, the hardening portions are the second journal portion  2  ( 2 J) from the left of the crankshaft  1  shown in  FIG. 9  and the fourth journal portion  2  ( 4 J) from the left of the crankshaft  1  shown in  FIG. 9 . Note that the diameter of the second journal portion  2  ( 2 J) is 76.8 mm and the width thereof is 24.0 mm, while the diameter of the fourth journal portion  2  ( 4 J) is 76.8 mm and the width thereof is 23.5 mm. Therefore, the fourth journal portion  2  ( 4 J) has a width dimension slightly smaller (−0.5 mm) than that of the second journal portion  2  ( 2 J). 
     As shown in  FIG. 7 , it can be seen that in the case in which the conventional guide chips  8   a ,  8   b , and  8   c  for high frequency induction heating coil are used, the lower limit value of the non-hardened area of the second journal portion  2  ( 2 J) is smaller than the lower limit value of the specification, and that the non-hardened area of the fourth journal portion  2  ( 4 J) is barely within the range of the specification. On the other hand, it can be seen from the figure that in the case in which the guide chips  21   a ,  21   b  and  21   c  for high frequency induction heating coil according to the present embodiment are used, the non-hardened area of the journal portion is sufficiently within the range of the specification. Furthermore, the variation in the non-hardened area tends to become comparatively large in the portion  37  with the oil hole  36  in the journal portion  2 . However, it can be seen from  FIG. 8  that in the case in which the guide chips  21   a ,  21   b  and  21   c  for a high frequency induction heating coil according to the present embodiment are used even for the portion  37  with the oil hole  36  in the journal portion  2 , the non-hardened area is sufficiently within the range of the specification. 
     Note that  FIGS. 5 and 6  show hardened cases S 3  and S 4  formed in the case in which the guide chips  21   a ,  21   b  and  21   c  for high frequency induction heating coil according to the present embodiment are used, and it is confirmed from the figures that the hardened cases S 3  and S 4  are formed at substantially correct positions in both the portion  35  without the oil hole  34  and the portion  37  with the oil hole  36  in the journal portion  2 . 
     In the above, an embodiment according to the present invention has been described. However, the present invention is not limited to the embodiment, and various modifications and changes can be made within the scope and spirit of the present invention. For example, in the above-described embodiment, it is configured such that the journal portion  2  of the crankshaft  1  is subjected to high frequency induction heating so as to be hardened by using the guide chips  21   a ,  21   b  and  21   c  for high frequency induction heating coil, but the present invention can also be applied to the case in which the pin portion  4  of the crankshaft  1  is subjected to high frequency induction heating so as to be hardened by using the guide chips  21   a ,  21   b  and  21   c  for high frequency induction heating coil. Furthermore, in the above-described embodiment, the three guide chips  21   a ,  21   b  and  21   c  for high frequency induction heating coil are configured in a flexible manner, but only one of the guide chips may be configured in the flexible manner. Also in this case, the guide chips for high frequency induction heating coil, and thus the semi-open saddle type high frequency induction heating coil, can be correctly positioned in the width direction of the journal portion or the pin portion. Furthermore, in the above-described embodiment, it is configured such that the three guide chips  21   a ,  21   b  and  21   c  for high frequency induction heating coil are used, but it is possible to use two or four or more guide chips for high frequency induction heating coil. Furthermore, in the above-described embodiment, it is set such that the width of the gap  32  between the chip fixing plates  30   a  and  30   a  facing each other is reduced to become the width W 3  at the time when the guide chips  21   a ,  21   b  and  21   c  for high frequency induction heating coil are inserted between the mutually adjacent counterweight portions  3  and  3  (see  FIG. 4(   b )). However, it may also be set such that the width of the gap  32  is reduced to become zero (the gap  32  is eliminated) at that time. In the above, there has been described the structure of the guide chips for high frequency induction heating coil according to the present invention. However, the guide chip structure is not limited to the above-described structure, and it is obvious that those included in the technical scope of the present invention can be applied.