Patent Publication Number: US-2021176833-A1

Title: Heating coil and quenching device

Description:
BACKGROUND 
     Technical Field 
     An embodiment relates to a heating coil used for induction heating of a roller guide groove formed on an inner peripheral surface of an outer ring of a tripod type constant velocity joint, and a quenching device including the heating coil. 
     Related Art 
     A tripod type constant velocity joint with variable transmission distance is known as a type of constant velocity joint that performs power transmission between two shafts having a crossing angle. The tripod type constant velocity joint includes an outer ring and a shaft. An inner peripheral surface of the outer ring is provided with three axially extending roller guide grooves. The tip of the shaft is provided with three radially projecting short shafts, and a roller is mounted on each short shaft. The tip of the shaft is inserted into the outer ring, and each roller is housed in the roller guide groove. When the roller slides in the roller guide groove, the transmission distance is changed. 
     In order to increase the surface hardness of the roller guide groove that is in sliding contact with the roller, the roller guide groove is quenched in some cases, and the heating at the time of quenching is performed by high-frequency induction heating, for example (See JP-UM-A-2-38459 and JP-UM-A-5-54534). In order to avoid the shaft inserted into the outer ring from coming off, for example, a snap ring abutting against the roller is attached to the outer ring. In the tripod type constant velocity joint described in JP-A-11-336782 and JP-A-2006-153135, instead of the snap ring, a projection raised inside the groove is formed at an opening side end of the roller guide groove. 
     SUMMARY 
     As in the tripod type constant velocity joint described in JP-A-11-336782 and JP-A-2006-153135, the projection is formed at the opening side end of the roller guide groove, and the shaft is avoided from coming off by the abutment between the projection and the roller, whereby the snap ring is omitted, and thus it is possible to omit a process of forming, in the outer ring, the groove to which the snap ring is mounted, and to reduce the cost. However, the projection is formed by plastically deforming the material of the opening side end of the roller guide groove. Therefore, when the roller guide groove is quenched, it is necessary to provide an unquenched region at the opening side end. 
     It is conceivable that in a case where the unquenched region is provided at the opening side end of the roller guide groove, for example, when the roller guide groove is subjected to high-frequency induction heating, temperature rise of the opening side end is suppressed by injecting a cooling liquid to the opening side end of the roller guide groove and/or its vicinity. However, the injection amount of the cooling liquid is small, and it is thus very difficult to stably inject the cooling liquid. Due to the variation in the injection of the cooling liquid, the opening side end and its vicinity are overheated, and the unquenched region is not stably formed, and a defect such as a quench crack can occur. 
     The embodiment has been made in view of the above circumstances, and its object to provide a heating coil and a quenching device that are capable of stably forming an unquenched region at an opening side end of a roller guide groove. 
     A heating coil according to an aspect of the invention is a heating coil used for induction heating of a roller guide groove formed on an inner peripheral surface of an outer ring of a tripod type constant velocity joint, including: a coil body inserted into the outer ring through an opening on one end side of the outer ring; and a plurality of shield members disposed to face an inner peripheral surface of an opening side end of the outer ring, wherein the coil body includes three heaters that are disposed at intervals in a circumferential direction around a central axis and each housed in the roller guide groove, and three connectors that are interposed between the two heaters adjacent to each other in the circumferential direction and project from the opening of the outer ring, the three connectors connecting the three heaters in series with a power source, the heater has a first heating conductor and a second heating conductor disposed to face each other on both side surfaces of the roller guide groove, which are a pair of heating conductors extending along the central axis, the connector has a first connection conductor extending from the second heating conductor of one heater of the two heaters adjacent to each other in the circumferential direction and a second connection conductor extending from the first heating conductor of the other heater, which are a pair of connection conductors extending along the central axis, the shield member is provided for each of the connectors, and is disposed in a circumferential gap between the first connection conductor and the second connection conductor of the connector, and a circumferential gap between the first connection conductor and the second connection conductor of the connector is larger than a circumferential gap between the second heating conductor of one heater of the two heaters adjacent to each other in the circumferential direction and the first heating conductor of the other heater. 
     A quenching device according to an aspect of the invention is a quenching device including the heating coil and a cooling jacket that injects a cooling liquid onto an inner peripheral surface of the outer ring in which the roller guide groove is subjected to induction heating by the heater of the heating coil, in which the roller guide groove is subjected to induction heating in a state where a positional relationship between the heating coil and the outer ring is fixed. 
     According to an embodiment of the invention, it is possible to provide a heating coil and a quenching device that are capable of stably forming an unquenched region at an opening side end of a roller guide groove, and to reduce the manufacturing cost of a tripod type constant velocity joint and its outer ring. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a cross-sectional view of an example of a tripod type constant velocity joint for explaining an embodiment of the invention; 
         FIG. 2  is a plan view of the outer ring of  FIG. 1 ; 
         FIG. 3  is a schematic view of a quenching device used for quenching of a roller guide groove of the outer ring of  FIG. 1 ; 
         FIG. 4  is a perspective view of a coil body of a heating coil of the quenching device of  FIG. 3 ; 
         FIG. 5  is a bottom view of the heating coil of  FIG. 4 ; 
         FIG. 6  is a bottom view of the coil body of the heating coil of  FIG. 4 ; 
         FIG. 7  is a schematic view showing the flow of the induction current flowing through the outer ring that is subjected to induction heating by the heating coil of  FIG. 4 ; 
         FIG. 8  is a schematic view showing a quenching pattern of the outer ring quenched using the heating coil of  FIG. 4 ; 
         FIG. 9  is a plan view of the outer ring of an experiment example; and 
         FIG. 10  is a schematic view of the heating coil of some of the experiment examples. 
     
    
    
     DETAILED DESCRIPTION 
       FIGS. 1 and 2  show an example of a tripod type constant velocity joint for explaining an embodiment of the invention. 
     A tripod type constant velocity joint (Hereinafter referred to as a constant velocity joint.)  1  includes an outer ring  2  and a shaft  3 . The constant velocity joint  1  is used for power transmission between an input side differential and an output side drive shaft in a vehicle such as an automobile. The outer ring  2  is connected to the differential, and the shaft  3  is configured as a drive shaft. 
     The outer ring  2  has an opening at one axial end side. The inner peripheral surface of the outer ring  2  is provided with three roller guide grooves  4  and three protrusions  5 . The three roller guide grooves  4  are disposed circumferentially at intervals of 120°, and axially extend from an opening end surface  2   a  of the outer ring  2 . The three protrusions  5  axially extend from the opening end surface  2   a  of the outer ring  2  between the two circumferentially adjacent roller guide grooves  4 . 
     The shaft  3  has three short shafts  6  at the tip. The three short shafts  6  are circumferentially disposed at intervals of 120°, and radially project from the tip of the shaft  3 . A roller  7  is mounted on each short shaft  6 . The tip of the shaft  3  is inserted into the outer ring  2 , and the roller  7  is housed in the roller guide groove  4 . The roller  7  can slide both side surfaces  4   a  and  4   b  of the roller guide groove  4  in the extending direction of the roller guide groove  4 . 
     The short shaft  6  rotatably supports the roller  7 , and permits the inclination of the rotation axis of the roller  7  with respect to the central axis of the short shaft  6  to support the roller  7 . A crossing angle θ is set between the central axis of the outer ring  2  and the central axis of the shaft  3  with the inclination of the rotation axis of the roller  7 . From the viewpoint of expanding the settable crossing angle θ, a chamfer surface  5   b  inclined so as to expand the opening of the outer ring  2  is formed at the opening side end of the protrusion  5 . 
     As the roller  7  slides on the both side surfaces  4   a  and  4   b  of the roller guide groove  4 , the transmission distance (e.g., the distance between the differential and the drive shaft) is changed. The both side surfaces  4   a  and  4   b  of the roller guide groove  4  in sliding contact with the roller  7  are quenched, and the surface hardness of the both side surfaces  4   a  and  4   b  is increased. A surface  5   a  of the protrusion  5  circumferentially adjacent to the both side surfaces  4   a  and  4   b  is also quenched. 
     However, the chamfer surface  5   b , which is the opening side ends of the both side surfaces  4   a  and  4   b  of the roller guide groove  4  and the opening side end of the surface  5   a  of the protrusion  5 , is respectively provided with an unquenched region extending to the opening end surface  2   a  of the outer ring  2 . In the unquenched regions of the both side surfaces  4   a  and  4   b , a projection  8  raised toward the inside of the roller guide groove  4  is formed. The projection  8  is formed by driving a pin or the like into the opening end surface  2   a  of the outer ring  2  along the edge of the both side surfaces  4   a  and  4   b , for example, and plastically deforming the material of the unquenched region of the both side surfaces  4   a  and  4   b . The shaft  3  is avoided from coming off from the outer ring  2  by the projection  8  and the roller  7  abutting against each other. 
       FIGS. 3 to 6  show an example of the quenching device and the heating coil, for explaining an embodiment of the invention. 
     A quenching device  100  is used for quenching the outer ring  2  of the constant velocity joint  1  described above. The quenching device  100  includes a heating coil  101  and a first cooling jacket  102 . The heating coil  101  is inserted into the outer ring  2  through an opening on one end side of the outer ring  2 , and subjects the both side surfaces  4   a  and  4   b  of the roller guide groove  4  of the outer ring  2  to induction heating. In the first cooling jacket  102 , the both side surfaces  4   a  and  4   b  are rapidly cooled by injecting a cooling liquid to the inner peripheral surface of the outer ring  2  in which the both side surfaces  4   a  and  4   b  of the roller guide groove  4  have been subjected to induction heating by the heating coil  101 . Thus, the both side surfaces  4   a  and  4   b  are quenched. 
     The quenching device  100  further includes a second cooling jacket  103 . The second cooling jacket  103  injects the cooling liquid to the outer peripheral surface of the outer ring  2  when the heating coil  101  subjects the both side surfaces  4   a  and  4   b  of the roller guide groove  4  to induction heating. This avoids the outer ring  2  from burning out. The burning out means that the quenching hardening layer reaches from the inner diameter side to the outer diameter side in quenching of both side surfaces  4   a  and  4   b  of the roller guide groove  4 . 
     The quenching device  100  performs induction heating and rapid cooling of the both side surfaces  4   a  and  4   b  of the roller guide groove  4  in a state where the positional relationship between the heating coil  101  and the outer ring  2  is fixed. Productivity is excellent compared to the case of performing induction heating and rapid cooling of the both side surfaces  4   a  and  4   b  of the roller guide groove  4  while moving the heating coil and the outer ring  2  relatively in the axial direction of the outer ring  2 . 
     The heating coil  101  includes a coil body  110  and a plurality of shield members  111 . The coil body  110  has three heaters  112 A,  112 B, and  112 C inserted into the outer ring  2  through an opening on one end side of the outer ring  2 , and three connectors  113 A,  113 B, and  113 C projecting from the opening of the outer ring  2 . The heaters  112 A,  112 B, and  112 C are disposed around a central axis X of the coil body  110  at intervals of 120°, and when inserted into the outer ring  2 , they are disposed in the roller guide groove  4  of the outer ring  2 . 
     The heater  112 A has a pair of a first heating conductor  120  and a second heating conductor  121 . The first heating conductor  120  extends along the central axis X and is disposed to face one side surface of the roller guide groove  4 . The second heating conductor  121  extends along the central axis X and is disposed to face the other side surface of the roller guide groove  4 . The tip end of the first heating conductor  120  and the tip end of the second heating conductor  121  disposed on the bottom side of the outer ring  2  are coupled via a bridge conductor  122 , and the heater  112 A is formed in a U shape as a whole. The heater  112 B and the heater  112 C also have the first heating conductor  120 , the second heating conductor  121 , and the bridge conductor  122 , and, similarly to the heater  112 A, are formed in a U shape as a whole. 
     The connector  113 A has a pair of a first connection conductor  123  and a second connection conductor  124 . The first connection conductor  123  extends from the second heating conductor  121  of the heater  112 A along the central axis X. The second connection conductor  124  extends from the first heating conductor  120  of the heater  112 B along the central axis X. The tip end of the first connection conductor  123  and the tip end of the second connection conductor  124  are coupled via a bridge conductor  125 , and the connector  113 A is formed in a U shape as a whole. The connector  113 A connects the two circumferentially adjacent heaters  112 A and heater  112 B in series. 
     The connector  113 B has a pair of the first connection conductor  123  and the second connection conductor  124 . The first connection conductor  123  extends from the second heating conductor  121  of the heater  112 B along the central axis X. The second connection conductor  124  extends from the first heating conductor  120  of the heater  112 C along the central axis X. The tip end of the first connection conductor  123  and the tip end of the second connection conductor  124  are coupled via a bridge conductor  125 , and, similarly to the connector  113 A, the connector  113 B is formed in a U shape as a whole. The connector  113 B connects the two circumferentially adjacent heaters  112 B and heater  112 C in series. 
     The connector  113 C has a pair of the first connection conductor  123  and the second connection conductor  124 . The first connection conductor  123  extends from the second heating conductor  121  of the heater  112 C along the central axis X. The second connection conductor  124  extends from the first heating conductor  120  of the heater  112 A along the central axis X. The first connection conductor  123  and the second connection conductor  124  of the connector  113 C are connected to a power source, and the heaters  112 A,  112 B, and  112 C are connected in series to the power source via the connectors  113 A,  113 B, and  113 C. 
     A conductor group (the first heating conductor  120 , the second heating conductor  121 , the bridge conductor  122 , the first connection conductor  123 , the second connection conductor  124 , and the bridge conductor  125 ) forming the heaters  112 A,  112 B, and  112 C and the connectors  113 A,  113 B, and  113 C are made of a tubular material and forms a continuous internal flow path  126 . A cooling liquid such as water flows through in the internal flow path  126 . The coil body  110 , which generates heat by energization, is cooled by the cooling liquid flowing through in the internal flow path  126 . 
     A circumferential interval D 1  between the first connection conductor  123  and the second connection conductor  124  of each of the connectors  113 A,  113 B, and  113 C is larger than a circumferential interval D 2  between the second heating conductor  121  of one heater (e.g., the heater  112 C) and the first heating conductor  120  of the other heater (e.g., the heater  112 A) among the two circumferentially adjacent heaters (e.g., the heater  112 C and the heater  112 A). 
     The shield member  111  is provided for each of the connectors  113 A,  113 B, and  113 C, and is disposed between the first connection conductor  123  and the second connection conductor  124  of each heater. The first heating conductor  120  and the second heating conductor  121  of each of the heaters  112 A,  112 B, and  112 C are shorter than the roller guide groove  4  of the outer ring  2 , and housed in the roller guide groove  4 . Therefore, the shield member  111  disposed on the base end side of the first connection conductor  123  and the second connection conductor  124  is housed inside the opening side end of the outer ring  2  and disposed to face the chamfer surface  5   b  of the protrusion  5 . 
     Since the circumferential interval D 1  is larger than the circumferential interval D 2 , there are steps occurring at a junction between the second heating conductor  121  and the first connection conductor  123  and a junction between the first heating conductor  120  and the second connection conductor  124 . These junctions may be formed in a stepped shape or a slope shape, for example. The shape of the junction is appropriately set in accordance with the shape of the roller guide groove  4  of the outer ring  2 , the shape of the shield member  111  disposed between the first connection conductor  123  and the second connection conductor  124 , and the like. The shape of the shield member  111  can also be appropriately set in accordance with the shape of the protrusion  5  of the outer ring  2  or the like, and, for example, since the chamfer surface  5   b  is inclined, the surface of the shield member  111  facing the chamfer surface  5   b  may be inclined similarly. 
     The coil body  110  and the plurality of shield members  111  are supported by a support  114 . The support  114  is made of an insulation material such as ceramics. The support  114  further supports the outer ring  2  in this example in which induction heating and rapid cooling of the both side surfaces  4   a  and  4   b  of the roller guide groove  4  are performed in a state where the positional relationship between the heating coil  101  and the outer ring  2  is fixed. 
     The coil body  110  is fixed to the support  114 . On the other hand, the shield member  111  is attached to and detached from the support  114  via an appropriate spacer  115 . By changing the thickness of the spacer  115 , the position of the shield member  111  between the first connection conductor  123  and the second connection conductor  124  changes along the central axis X, and the distance between the shield member  111  and the chamfer surface  5   b  changes. 
       FIG. 7  shows the induction current flowing through the outer ring  2  that is subjected to induction heating by the heating coil  101 , and  FIG. 8  shows a quenching pattern of the outer ring  2 . In  FIG. 8 , the hatched region indicates a quenched region. 
     When a high-frequency current is supplied from the power source to the coil body  110 , an induction current I flows through the inner peripheral surface of the outer ring  2 . The induction current I basically flows along the first heating conductor  120 , the second heating conductor  121 , and the bridge conductor  122  of each of the heaters  112 A,  112 B, and  112 C, and flows through the both side surfaces  4   a  and  4   b  of the roller guide groove  4  in the extending direction of the roller guide groove  4 . At the opening side end of the outer ring  2 , the induction current I flows across the surface  5   a  of the protrusion  5  from the side surface  4   a  (or the side surface  4   b  ) to the side surface  4   b  (or the side surface  4   a  ) adjacent to each other circumferentially sandwiching the protrusion  5 . 
     Here, the first heating conductor  120  and the second heating conductor  121  are shorter than the roller guide groove  4  of the outer ring  2 , and the first connection conductor  123  and the second connection conductor  124  are disposed to face each other at the opening side end parts of the both side surfaces  4   a  and  4   b  of the roller guide groove  4 . As described above, the circumferential interval D 1  between the first connection conductor  123  and the second connection conductor  124  is set larger than the circumferential interval D 2  between the first heating conductor  120  and the second heating conductor  121  (see  FIG. 6 ). Therefore, the coil gap between the both side surfaces  4   a  and  4   b  and the coil body  110  is relatively expanded at the opening side end of the both side surfaces  4   a  and  4   b . Furthermore, the shield member  111  is disposed to face the chamfer surface  5   b , which is the opening side end of the surface  5   a  of the protrusion  5 . Therefore, the magnetic field at the opening side end of the both side surfaces  4   a  and  4   b  and the chamfer surface  5   b  is attenuated, and the temperature rise of the opening side end of both side surfaces  4   a  and  4   b  and the chamfer surface  5   b  is suppressed. Due to this, as shown in  FIG. 8 , the opening side end of the both side surfaces  4   a  and  4   b  and the chamfer surface  5   b  are each provided with an unquenched region extending to the opening end surface  2   a  of the outer ring  2 . 
     Furthermore, since the circumferential interval D 1  between the first connection conductor  123  and the second connection conductor  124  is set relatively large, the shield member  111  disposed between the first connection conductor  123  and the second connection conductor  124  can be made large. This can increase the temperature rise suppression effect of the chamfer surface  5   b  and the like based on the shield member  111 . The induction current also flows through in the shield member  111  disposed close to the coil body  110 , and the heat capacity of the shield member  111  can be increased to avoid the erosion of the shield member  111 . 
     A quenching relief width Wa from the opening end surface  2   a  of the unquenched region provided at the opening side end of the both side surfaces  4   a  and  4   b  of the roller guide groove  4  and a quenching relief width Wb from the opening end surface  2   a  of the unquenched region provided at the chamfer surface  5   b  of the protrusion  5  can be adjusted based on the distance between the shield member  111  and the chamfer surface  5   b . The distance between the shield member  111  and the chamfer surface  5   b  can be changed depending on the thickness of the spacer  115  interposed between the shield member  111  and the support  114 . Due to this, it is not only possible to appropriately adjust the quenching relief width Wa of the both side surfaces  4   a  and  4   b  in accordance with the specifications of quenching, but also possible to use the common heating coil  101  for the outer ring  2  having different lengths of the roller guide grooves  4 . 
     The material of the shield member  111  may be a magnetic metal material such as steel or may be a non-magnetic metal material such as copper, but it is preferably a non-magnetic metal material from the viewpoint of avoiding excessive suppression of temperature rise of the chamfer surface  5   b  or the like. 
     An experiment example will be described below.  FIG. 9  shows the outer ring  2  of an experiment example. 
     In the experiment example, quenching of the both side surfaces  4   a  and  4   b  was performed by setting the quenching relief width Wa of the unquenched region provided at the opening side end of the both side surfaces  4   a  and  4   b  of the roller guide groove  4  to equal to or greater than 4 mm to equal to or less than 7 mm. The quenched outer ring  2  was cut at the cut surfaces a to f shown in  FIG. 9 , and the quenching relief width Wa was measured at each cut surface. In the experiment examples  1  to  11 , quenching was performed using a heating coil  201  shown in  FIG. 10 , and in the experiment examples 12 to 14, quenching was performed using the heating coil  101  described above. 
     Here, referring to the heating coil  201  shown in  FIG. 10 , the heating coil  201  includes a coil body  210 , and the coil body  210 , similarly to the coil body  110  of the heating coil  101 , includes three heaters  212  and three connectors  213 . However, the circumferential interval (D 1  shown in  FIG. 6 ) between a first connection conductor  223  and a second connection conductor  224  of the connector  213  is set to be identical to the circumferential interval (D 2  shown in  FIG. 6 ) between a first heating conductor  220  of one heater  212  and a second heating conductor  221  of the other heater  212  of the circumferentially adjacent two heaters  212 . The heating coil  201  includes a chamfer cooling jacket  211  in place of the shield member  111  of the heating coil  101 , and the chamfer cooling jacket  211  injects a cooling liquid onto the chamfer surface  5   b  of the protrusion  5  and the opening end surface  2   a  of the outer ring  2 . 
     The measurement results of the experiment examples 1 to 11 are shown in Table 1, and the measurement results of the experiment examples 12 to 14 are shown in Table 2. 
     
       
         
           
               
               
             
               
                 TABLE 1 
               
             
            
               
                   
               
               
                 Experiment 
                 Quenching relief width Wa [mm] 
               
            
           
           
               
               
               
               
               
               
               
            
               
                 examples 
                 Cut surface a 
                 Cut surface b 
                 Cut surface c 
                 Cut surface d 
                 Cut surface e 
                 Cut surface f 
               
               
                   
               
            
           
           
               
               
               
               
               
               
               
            
               
                 No. 1 
                 4.5 
                 4.0 
                 5.0 
                 3.0 
                 3.8 
                 4.8 
               
               
                 No. 2 
                 3.4 
                 3.9 
                 3.5 
                 4.3 
                 4.2 
                 2.7 
               
               
                 No. 3 
                 4.6 
                 4.8 
                 3.0 
                 4.9 
                 4.7 
                 3.5 
               
               
                 No. 4 
                 3.5 
                 3.6 
                 3.2 
                 4.5 
                 3.0 
                 3.9 
               
               
                 No. 5 
                 3.9 
                 5.5 
                 3.9 
                 5.0 
                 4.2 
                 3.2 
               
               
                 No. 6 
                 4.4 
                 6.1 
                 4.0 
                 4.8 
                 5.4 
                 3.7 
               
               
                 No. 7 
                 4.7 
                 4.8 
                 3.3 
                 4.5 
                 4.7 
                 2.9 
               
               
                 No. 8 
                 3.2 
                 5.4 
                 3.1 
                 4.6 
                 5.2 
                 5.3 
               
               
                 No. 9 
                 3.8 
                 4.9 
                 4.3 
                 4.9 
                 4.2 
                 3.2 
               
               
                 No. 10 
                 4.2 
                 4.7 
                 5.8 
                 5.9 
                 6.1 
                 2.8 
               
               
                 No. 11 
                 4.6 
                 5.9 
                 3.8 
                 4.8 
                 6.7 
                 3.1 
               
               
                   
               
            
           
         
       
     
     
       
         
           
               
               
             
               
                 TABLE 2 
               
             
            
               
                   
               
               
                 Experiment 
                 Quenching relief width Wa [mm] 
               
            
           
           
               
               
               
               
               
               
               
            
               
                 examples 
                 Cut surface a 
                 Cut surface b 
                 Cut surface c 
                 Cut surface d 
                 Cut surface e 
                 Cut surface f 
               
               
                   
               
            
           
           
               
               
               
               
               
               
               
            
               
                 No. 12 
                 6.5 
                 6.0 
                 6.0 
                 5.5 
                 6.5 
                 6.3 
               
               
                 No. 13 
                 6.5 
                 6.0 
                 6.0 
                 6.0 
                 6.5 
                 6.0 
               
               
                 No. 14 
                 7.0 
                 7.0 
                 6.5 
                 6.8 
                 6.5 
                 7.0 
               
               
                   
               
            
           
         
       
     
     For the specifications of the quenching relief width Wa of equal to or greater than 4 mm to equal to or less than 7 mm, in the experiment examples 1 to 11, where D 1 =D 2  was set and the quenching was performed by using the heating coil  201  suppressing the temperature rise of the chamfer surface  5   b  by injecting the cooling liquid, the quenching relief width Wa was out of the range of the above specifications at one or more cut surfaces in every example. On the other hand, in the experiment examples 12 to 14, where D 1  &gt;D 2  was set and the quenching was performed by using the heating coil  101  suppressing the temperature rise of the chamfer surface  5   b  by the shield member  111 , the quenching relief width Wa was within the range of the above specifications in all the cut surfaces in every example. The above results indicate that according to the heating coil  101 , an unquenched region can be stably formed at the opening side end of the both side surfaces  4   a  and  4   b  of the roller guide groove  4 . 
     As described above, the heating coil disclosed in the present description is a heating coil used for induction heating of a roller guide groove formed on an inner peripheral surface of an outer ring of a tripod type constant velocity joint, including: a coil body inserted into the outer ring through an opening on one end side of the outer ring; and a plurality of shield members disposed to face an inner peripheral surface of an opening side end of the outer ring, wherein the coil body includes three heaters that are disposed at intervals in a circumferential direction around a central axis and each housed in the roller guide groove, and three connectors that are interposed between the two heaters adjacent to each other in the circumferential direction and project from the opening of the outer ring, the three connectors connecting the three heaters in series with a power source, the heater has a first heating conductor and a second heating conductor disposed to face each other on both side surfaces of the roller guide groove, which are a pair of heating conductors extending along the central axis, the connector has a first connection conductor extending from the second heating conductor of one heater of the two heaters adjacent to each other in the circumferential direction and a second connection conductor extending from the first heating conductor of the other heater, which are a pair of connection conductors extending along the central axis, the shield member is provided for each of the connectors, and is disposed between the first connection conductor and the second connection conductor of the connector, and a circumferential interval between the first connection conductor and the second connection conductor of the connector is larger than a circumferential interval between the second heating conductor of one heater of the two heaters adjacent to each other in the circumferential direction and the first heating conductor of the other heater. 
     The heating coil disclosed in the present description includes a support that supports the coil body and the shield member, and the shield member is supported by the support so as to be displaceable along the central axis between the first connection conductor and the second connection conductor of the connector. 
     In the heating coil disclosed in the present description, the shield member is made of a non-magnetic metal material. 
     The quenching device disclosed in the present description includes the heating coil and a cooling jacket that injects a cooling jacket that injects a cooling liquid onto an inner peripheral surface of the outer ring in which the roller guide groove is subjected to induction heating by the heater of the heating coil, and the roller guide groove is subjected to induction heating in a state where a positional relationship between the heating coil and the outer ring is fixed.