Abstract:
A method of manufacturing a scroll member for a compression mechanism installed in a scroll compressor includes a casting step and a cutting step. An iron casting is formed in the casting step, which includes a spiraling part. The iron casting obtained in the casting step is cut during the cutting step in order to obtain a final shape of the scroll member. The iron casting may include a fixed part having a central portion with a first axial thickness and an external periphery portion with a second axial thickness larger than the first axial thickness before the cutting step. A dimension of a specified portion of the spiraling part may be larger before the cutting step is performed than after the cutting step is performed, with the specified portion preferably disposed toward an external periphery of the spiraling part.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This U.S. National stage application claims priority under 35 U.S.C. §119(a) to Japanese Patent Application No. 2007-092274, filed in Japan on Mar. 30, 2007, the entire contents of which are hereby incorporated herein by reference. 
     TECHNICAL FIELD 
     The present invention relates to a scroll member and a method for manufacturing the same. 
     BACKGROUND ART 
     A scroll-type compressor comprises a compression mechanism for compressing a refrigerant. The compression mechanism has a fixed scroll and an orbiting scroll. 
     Methods for forming cast iron by using a metal die, for example, have been used conventionally as methods for manufacturing fixed scrolls, orbiting scrolls, and other scroll members. In conventional methods, cast iron has been formed into substantially the same shape of the finished products of scroll members (see Japanese Laid-open Patent Application No. 2005-36693, for example). 
     The art pertaining to the present invention is shown hereinbelow. 
     SUMMARY OF THE INVENTION 
     Technical Problem 
     However, if cast iron is formed into the same shape of the finished products of the scroll members, the portion extending in a spiraling formation of low thickness is susceptible to cooling due to a low heat capacity, and the hardness cannot be increased. Therefore, when the compression mechanism is driven, there is a danger that this portion will suffer wear or deformation. 
     The strength of this portion can be increased by increasing the thickness of this portion, but this is undesirable because the size of the compression mechanism is increased. 
     The present invention was made in view of the circumstances described above, and an object thereof is to reduce wear and deformation in a scroll member. 
     Solution to Problem 
     A method for manufacturing a scroll member according to a first aspect of the invention is a method for manufacturing a scroll member used in a compression mechanism installed in a scroll compressor, the method comprising a step (a) and a step (b). In step (a), cast iron is formed and an iron casting is obtained, the iron casting having a spiraling part extending in a spiraling formation and a fixed part for fixing the spiraling part. In step (b), the iron casting obtained in step (a) is cut and the scroll member is obtained. The fixed part of the iron casting obtained in step (a) has a greater thickness in a portion near the external periphery than the thickness of a portion near the center of the spiral. 
     A method for manufacturing a scroll member according to a second aspect of the invention is the method for manufacturing a scroll member according to the first aspect of the invention, wherein the iron casting obtained in step (a) also has a protruding part. The protruding part is fixed to the fixed part on the side opposite the spiraling part and is given an annular shape encircling the center. The portion near the external periphery is positioned on the external side of the protruding part when the iron casting is viewed from the side having the spiraling part. 
     A method for manufacturing a scroll member according to a third aspect of the invention is a method for manufacturing a scroll member used in a compression mechanism installed in a scroll compressor, the method comprising a step (a) and a step (b). In step (a), cast iron is formed and an iron casting is obtained, the iron casting having a spiraling part extending in a spiraling formation. In step (b), the iron casting obtained in step (a) is cut and the scroll member is obtained. In the iron casting obtained in step (a), a dimension of a specified portion of the spiraling part is greater than a dimension of the same portion after step (b) is performed. The specified portion extends along the spiral from an end on the external periphery of the spiral to a position different from an end at the center of the spiral. 
     A method for manufacturing a scroll member according to a fourth aspect of the invention is the method for manufacturing a scroll member according to the third aspect of the invention, wherein the iron casting obtained in step (a) also has a fixed part for fixing the spiraling part, and a protruding part. The protruding part is fixed to the fixed part on the side opposite the spiraling part and is positioned near the center. The specified portion is positioned farther peripherally outward than a side surface of the protruding part when the iron casting is viewed from the side having the spiraling part. 
     A method for manufacturing a scroll member according to a fifth aspect of the invention is the method for manufacturing a scroll member according to the fourth aspect of the invention, wherein the dimension of the specified portion is greater than the dimension of a portion of the spiraling part located farther peripherally inward than the side surface. 
     A method for manufacturing a scroll member according to a sixth aspect of the invention is the method for manufacturing a scroll member according to any of the third through fifth aspects of the invention, wherein the specified portion extends around the center to a position located anywhere from a half circle up to a full circle from the end. 
     A method for manufacturing a scroll member according to a seventh aspect of the invention is the method for manufacturing a scroll member according to a sixth aspect of the invention, wherein the specified portion is cut in step (b) only at the portion on the external periphery. 
     A method for manufacturing a scroll member according to an eighth aspect of the invention is the method for manufacturing a scroll member according to any of the third through seventh aspects of the invention, wherein the dimension is the thickness of the spiraling part. 
     A method for manufacturing a scroll member according to a ninth aspect of the invention is the method for manufacturing a scroll member according to the eighth aspect of the invention, wherein the iron casting obtained in step (a) also has a fixed part for fixing the spiraling part. The height of the specified portion from the fixed part is greater than the same height after step (b) is performed. 
     A method for manufacturing a scroll member according to a tenth aspect of the invention is the method for manufacturing a scroll member according to any of the third through seventh aspects of the invention, wherein the iron casting obtained in step (a) also has a fixed part for fixing the spiraling part. The dimension is the height of the spiraling part from the fixed part. 
     A method for manufacturing a scroll member according to an eleventh aspect of the invention is the method for manufacturing a scroll member according to any of the third through tenth aspects of the invention, wherein the dimension of the specified portion decreases progressively going from the end on the external periphery toward the end at the center. 
     A method for manufacturing a scroll member according to a twelfth aspect of the invention is the method for manufacturing a scroll member according to any of the first through eleventh aspects of the invention, wherein the iron casting is formed by semi-molten die casting in step (a). 
     A scroll member according to a thirteenth aspect of the invention is a scroll member manufactured by the method according to any of the first through twelfth aspects of the invention. After step (b) is performed, the ratio of the height of the spiraling part from the fixed part to the thickness of the spiraling part is 8.5 or greater. 
     A compression mechanism according to a fourteenth aspect of the invention comprises the scroll member according to the thirteenth aspect of the invention as an orbiting scroll or a fixed scroll, or both. 
     A scroll compressor according to a fifteenth aspect of the invention comprises the compression mechanism according to the fourteenth aspect of the invention. 
     A scroll compressor according to a sixteenth aspect of the invention is the scroll compressor according to the fifteenth aspect of the invention for compressing a refrigerant including carbon dioxide as a main component. 
     Advantageous Effects of the Invention 
     With the method for manufacturing a scroll member according to the first aspect, since the fixed part in step (a) has a greater thickness in a portion near the external periphery than the thickness of a portion near the center, the portion near the external periphery has a greater heat capacity than the portion near the center. Consequently, the portion near the external periphery is more resistant to cooling than the portion near the center even after being formed, and even in the spiraling part, the portion near the external periphery is resistant to cooling. This allows the hardness of the portion near the external periphery to be increased in the spiraling part, and the difference in hardness from the portion near the center to be reduced. 
     With the method for manufacturing a scroll member according to the second aspect, the hardness of the portion at the external periphery in the spiraling part can be made greater than that of the protruding part. 
     With the method for manufacturing a scroll member according to the third aspect, the dimension of the portion near the end at the external periphery of the spiral is increased in step (a) to be greater than the same dimension after step (b) is performed, whereby the heat capacity of this portion is increased. Consequently, this portion is resistant to cooling even after being formed. The hardness of this portion can thereby be increased, and wear in the scroll member can also be reduced. 
     With the method for manufacturing a scroll member according to the fourth aspect, in the spiraling part, the hardness of the portion at the external periphery can be increased to be greater than that of the side surface of the protruding part. Consequently, in the spiraling part, it is possible to reduce the difference in hardness between the portion positioned on the internal side of the side surface of the protruding part and the portion positioned on the external side. 
     With the method for manufacturing a scroll member according to the fifth aspect, in the spiraling part, it is possible to reduce the difference in hardness between the portion positioned on the internal side of the side surface of the protruding part and the portion positioned on the external side. 
     With the method for manufacturing a scroll member according to the sixth aspect, it is possible to increase the hardness of the portion positioned in the external periphery of the spiral. 
     With the method for manufacturing a scroll member according to the seventh aspect, since the specified portion is positioned in the external periphery of the spiral, this portion is cut more readily at an external peripheral portion thereof. 
     With the method for manufacturing a scroll member according to the eighth aspect, the hardness of the spiraling part can be increased. 
     With the method for manufacturing a scroll member according to the ninth or tenth aspect, it is possible to increase the hardness of the portion at the distal end of the spiraling part when the spiraling part is viewed from the fixed part. 
     With the method for manufacturing a scroll member according to the eleventh aspect, variations in hardness in the specified portion can be reduced. 
     With the method for manufacturing a scroll member according to the twelfth aspect, the strength of the resulting scroll member can be increased by using semi-molten die casting. With the scroll member according to the thirteenth aspect, since the scroll member is manufactured by the method of any of claims  1  through  10 , the spiraling part has high strength, and is resistant to deformation even if the ratio of height to thickness is 8.5 or greater. Consequently, the scroll member can be reduced in size. 
     With the compression mechanism according to the fourteenth aspect, since strength is high in the portion near the end at the external periphery of the spiraling part, the scroll member is resistant to deformation. Consequently, the compression mechanism does not readily break down. 
     With the scroll compressor according to the fifteenth aspect, since the compression mechanism does not readily break down, the scroll compressor also does not readily break down. 
     With the scroll compressor according to the sixteenth aspect, the scroll compressor does not readily break down even if carbon dioxide is used, because the compression mechanism has high strength. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a drawing schematically depicting a scroll compressor  1  according to an embodiment of the present invention. 
         FIG. 2  pertains to an orbiting scroll and schematically depicts an iron casting  261  obtained in step (a). 
         FIG. 3  pertains to an orbiting scroll and schematically depicts an iron casting  261  obtained in step (a). 
         FIG. 4  pertains to an orbiting scroll and schematically depicts an iron casting  261  obtained in step (a). 
         FIG. 5  pertains to an orbiting scroll and schematically depicts an iron casting  261  obtained in step (a). 
         FIG. 6  pertains to an orbiting scroll and schematically depicts an iron casting  261  obtained in step (a). 
         FIG. 7  pertains to an orbiting scroll and schematically depicts an iron casting  261  obtained in step (a). 
         FIG. 8  pertains to a fixed scroll and schematically depicts an iron casting  241  obtained in step (a). 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       FIG. 1  is a drawing schematically depicting a scroll compressor  1  according to an embodiment of the present invention. The direction  91  is shown in  FIG. 1 , and hereinbelow the distal side of the arrow of the direction  91  is referred to as “up,” while the opposite side is referred to as “down.” 
     The scroll compressor  1  comprises a case  11  and a compression mechanism  15 . The case  11  has a cylindrical shape and extends along the direction  91 . The compression mechanism  15  is housed within the case  11 . 
     The compression mechanism  15  has a fixed scroll  24  and an orbiting scroll  26  and compresses refrigerant. A substance containing, e.g., carbon dioxide as a primary component can be used as the refrigerant. The fixed scroll  24  and the orbiting scroll  26  can both be understood as the scroll member used in the compression mechanism  15 . 
     The fixed scroll  24  includes a panel  24   a  and a compression member  24   b . The panel  24   a  is fixed to an internal wall  11   a  of the case  11 , and the compression member  24   b  is linked to the underside of the panel  24   a . The compression member  24   b  extends in a spiraling formation, and a groove  24   c  is formed inside the spiral. A hole  41  is formed in the central vicinity of the panel  24   a . Refrigerant compressed by the compression mechanism  15  is discharged through the hole  41 . 
     The orbiting scroll  26  has a panel  26   a  and a compression member  26   b . The compression member  26   b  is linked to the top side of the panel  26   a  and is made to extend in a spiraling formation. 
     The compression member  26   b  is accommodated within the groove  24   c  of the fixed scroll  24 . A space  40  between the compression member  24   b  and the compression member  26   b  is hermetically sealed by the panels  24   a ,  26   a  and is thereby used as a compression chamber. 
     In relation to the method for manufacturing a scroll member, the method for manufacturing the orbiting scroll  26  is described hereinbelow in the first and second embodiments, and the method for manufacturing the fixed scroll  24  is described in the third embodiment. In the fourth embodiment, the scroll members obtained by the pertinent manufacturing methods are described. 
     First Embodiment 
     The method for manufacturing the orbiting scroll  26 , which is a scroll member, comprises a step (a) and a step (b). 
     In step (a), cast iron is formed and an iron casting is obtained. For example, an iron casting of high strength can be obtained by forming cast iron by semi-molten die casting. In step (b), the iron casting obtained in step (a) is cut to obtain the orbiting scroll  26 . 
       FIGS. 2 and 3  schematically depict an iron casting  261  obtained in step (a). The iron casting  261  has a fixed part  261   a  and a spiraling part  261   b . The spiraling part  261   b  is fixed to the fixed part  261   a  and is made to extend in a spiraling formation around a center  9 . In  FIGS. 2 and 3 , the shape of the iron casting  261  obtained after step (b) is performed; i.e., the shape of the orbiting scroll  26  is shown by single-dashed lines. 
     In the fixed part  261   a  in  FIGS. 2 and 3 , the thickness d 2  of the portion  261   a   2  near the external periphery is greater than the thickness d 1  of the portion  261   a   1  near the center  9 . 
     By performing step (b) on the iron casting  261  obtained in step (a), the panel  26   a  is obtained from the fixed part  261   a , and the compression member  26   b  is obtained from the spiraling part  261   b.    
     By performing step (b), e.g., the thickness of the panel  26   a  may be made either the same as that of the portion  261   a   1  in the portion  261   a   2  ( FIG. 2 ), or greater than that of the portion  261   a   1  in the portion  261   a   2  ( FIG. 3 ). 
     According to the method for manufacturing this orbiting scroll  26 , the portion  261   a   2  near the external periphery has a greater thickness than the portion  261   a   1  near the center  9 , and therefore has a greater heat capacity. Consequently, the portion  261   a   2  resists cooling better than the portion  261   a   1  even after being formed, and the spiraling part  261   b  also resists cooling better in the portion  261   b   2  near the external periphery. The hardness of the portion  261   b   2  in the spiraling part  261   b  can thereby be increased. 
     In  FIGS. 2 and 3 , the iron casting  261  also has a protruding part  261   c . The protruding part  261   c  is fixed to the fixed part  261   a  from the side opposite the spiraling part  261   b , and is formed into an annular shape encircling the center  9 . 
     When the iron casting  261  is viewed from the side having the spiraling part  261   b , the portion  261   a   2  near the external periphery is positioned on the external side of the protruding part  261   c.    
     With this iron casting  261 , since the protruding part  261   c  is near the center  9 , the iron casting  261  has increased heat capacity in the portion near the center  9 , and this portion is resistant to cooling even after being formed. Consequently, the portion  261   b   1  near the center  9  in the spiraling part  261   b  is resistant to cooling, and the hardness of the portion  261   b   1  is also increased. 
     Moreover, in the spiraling part  261   b , the hardness of the portion  261   b   2  on the external side of the protruding part  261   c  can also be increased. Consequently, the difference in hardness between the portion  261   b   2  and the portion  261   b   1  is small, and variations in hardness in the iron casting  261  are small as well. 
     The protruding part  261   c  machined in step (b) is used in the orbiting scroll  26  as a bearing  26   c  ( FIG. 1 ), described hereinafter. 
     Second Embodiment 
     The present embodiment also relates to a method for manufacturing an orbiting scroll  26 , which is a scroll member. This manufacturing method comprises the same step (a) and step (b) as the first embodiment. However, the shape of the iron casting  261  obtained from step (a) differs from that of the first embodiment. The shape of the pertinent iron casting  261  is described hereinbelow using  FIGS. 4 through 7 . In  FIGS. 4 through 7 , the shape of the iron casting  261  obtained by performing step (b) is shown by single-dashed lines. 
     In the iron casting  261  obtained in step (a), the dimensions of specified portions of the spiraling part  261   b  are greater than the dimensions of these portions after step (b) is performed (Mode A). 
     Specifically, in the spiraling part  261   b  in  FIG. 4 , the thickness d 3  of the portion  261   b   3  is greater than the thickness h 1  of the portion  261   b   3  after step (b) is performed. In other words, in the aforementioned Mode A, the portion  261   b   3  is used as a specified portion, and the thickness d 3  of the portion  261   b   3  is used as the dimension. 
     The portion  261   b   3  extends along the spiral from an end  2612  on the external periphery of the spiral up to a position  2613  different from the end  2611  at the center  9  of the spiral. 
     In the spiraling part  261   b  in  FIG. 5 , the thickness d 4  of a portion  261   b   4  is greater than the thickness h 4  of the portion  261   b   4  after step (b) is performed. In other words, in the aforementioned Mode A, the portion  261   b   4  is used as the specified portion, and the thickness d 4  of the portion  261   b   4  is used as the dimension. 
     The portion  261   b   4  extends around the center  9  to a position located anywhere from a half circle (angle θ 1 =90° up to a full circle (angle θ 1 =180° from the end  2612 . The angle θ 1  is an angle formed by the direction in which the spiral extends from the end  2612  and the circumference of the center  9 , and  FIG. 5  shows a case in which θ 1  is 180°. 
     According to this method for manufacturing an orbiting scroll, the dimensions d 3 , d 4  of the portions  261   b   3 ,  261   b   4  near the end  2612  on the external periphery of the spiral in step (a) are made to be greater than the dimensions h 3 , h 4  after step (b) is performed, whereby the heat capacity of the portions  261   b   3 ,  261   b   4  is increased. These portions  261   b   3 ,  261   b   4  are consequently more resistant to cooling even after being formed. The hardness of the portions  261   b   3 ,  261   b   4  can thereby be increased, and wear in the orbiting scroll  26  can be reduced. 
     With the shape of the spiraling part  261   b  shown in  FIG. 5  in particular, in the spiraling part  261   b , the hardness of the portion  261   b   4  positioned on the external periphery of the spiral can be increased. 
     Returning to  FIG. 4 , the iron casting  261  also has a protruding part  261   c . The protruding part  261   c  is fixed to the fixed part  261   a  on the side opposite the spiraling part  261   b  and is positioned near the center  9 . 
     When the iron casting  261  is viewed from the side having the spiraling part  261   b , the portion  261   b   3  of the spiraling part  261   b  is positioned farther peripherally outward than the side surface  261   c   1  of the protruding part  261   c.    
     With this shape of the spiraling part  261   b , since the protruding part  261   c  is near the center  9 , the heat capacity of the portion of the iron casting  261  near the center  9  is greater, and this portion is resistant to cooling even after being formed. Consequently, in the spiraling part  261   b , the portion  261   b   1  near the center  9  is resistant to cooling, and the hardness of the portion  261   b   1  of the spiraling part  261   b  is also increased. In  FIG. 4 , the portion  261   b   1  is positioned farther peripherally inward than the side surface  261   c   1  of the protruding part  261   c  when the iron casting  261  is viewed from the side having the spiraling part  261   b.    
     Moreover, in the spiraling part  261   b , it is also possible to increase the hardness of the portion  261   b   2  positioned farther peripherally outward than the side surface  261   c   1  of the protruding part  261   c . Consequently, the difference between the hardness of the portion  261   b   3  and the hardness of the portion  261   b   1  is smaller, and variations in hardness in the iron casting  261  are smaller as well. 
     In  FIG. 4 , the thickness d 3  of the portion  261   b   3  of the spiraling part  261   b  is greater than the thickness d 11  of the portion  261   b   1  of the spiraling part  261   b.    
     With this shape of the spiraling part  261   b , the difference in hardness between the portion  261   b   3  and the portion  261   b   1  can be further reduced. 
     In  FIGS. 4 and 5 , both of the portions  261   b   3  and  261   b   4  of the spiraling part  261   b  extend from the end  2611  to the position  2613  at constant thicknesses d 3 , d 4 , but the thickness d 3  (d 4 ) may also be made to decrease progressively going from the end  2611  toward the position  2613 , as shown in  FIG. 6 , for example. The specifics of this can be understood in terms of the thickness d 3  (d 4 ) of the spiraling part  261   b  decreasing progressively from the end  2612  near the external periphery toward the end  2611  near the center  9 . 
     As described above, in cases in which the iron casting  261  has a protruding part  261 C, the portion near the center  9  of the iron casting  261  has greater heat capacity and is more resistant to cooling. Consequently, the portion  261   b   3  ( 261   b   4 ) in the external periphery of the spiraling part  261   b , becomes more resistant to cooling and increases more readily in hardness in portions nearer to the center  9 . Therefore, in the portion  261   b   3  ( 261   b   4 ) of the spiraling part  261   b , variations in hardness are likely to occur. 
     With this shape of the spiraling part  261   b  shown in  FIG. 6 , the nearer to the end  2612  at the external periphery, a greater thickness d 3  (d 4 ) of the portion  261   b   3  ( 261   b   4 ) corresponds to a greater possible increase in hardness in portions near the end  2612 . Consequently, variations in hardness in the portion  261   b   3  ( 261   b   4 ) can be reduced. 
     In the portions  261   b   3 ,  261   b   4  of the spiraling part  261   b  in all of the iron castings  261  shown in  FIGS. 4 through 6 , the portions in the external peripheries are cut in step (b) up to the positions of the single-dashed lines. 
     Since the portions  261   b   3 ,  261   b   4  of the spiraling part  261   b  are positioned in the external periphery of the spiral, the portions  261   b   3 ,  261   b   4  are easily cut in the external peripheral portions. 
     In  FIG. 7 , in a portion  261   b   5  on the external periphery of the side surface  261   c   1  of the protruding part  261   c  in the spiraling part  261   b , the height H 2  from the fixed part  261   a  is greater than the height h 5  of the portion  261   b   5  after step (b) is performed. In other words, in Mode A, the portion  261   b   5  of the spiraling part  261   b  is used as the specified portion, and the height H 2  of the portion  261   b   5  is used as the dimension. 
     With this shape of the spiraling part  261   b , in the portion  261   b   5  of the spiraling part  261   b , it is possible to increase the hardness of the portion located at the distal end when the portion is viewed from the fixed part  261   a.    
     In the spiraling part  261   b , the height H 2  of the portion  261   b   5  is made to be greater than the height H 1  of the portion  261   b   1  father peripherally inward than the side surface  261   c   1  of the protruding part  261   c , for the sake of reducing variations in hardness in the spiraling part  261   b.    
     In the present embodiment, the thicknesses d 3 , d 4  ( FIGS. 4 through 6 ) and height H 2  ( FIG. 7 ) of the spiraling part  261   b  may both be respectively greater than the thicknesses h 3 , h 4  and height h 5  after step (b) is performed. 
     It shall be apparent that the thicknesses d 3 , d 4  alone of the spiraling part  261   b  may be made to be greater than the thicknesses h 3 , h 4  after step (b) is performed as shown in  FIGS. 4 through 6 , and the height H 2  alone of the spiraling part  261   b  may be made to be greater than the height h 5  after step (b) is performed as shown in  FIG. 7 . 
     Third Embodiment 
     The method for manufacturing the fixed scroll  24 , which is a scroll member, comprises a step (a) and a step (b), similar to the second embodiment. 
       FIG. 8  schematically depicts an iron casting  241  obtained in step (a) in the manufacturing of a fixed scroll  24 . The iron casting  241  has a fixed part  241   a  and a spiraling part  241   b . The spiraling part  241   b  is fixed to the fixed part  241   a  and is made to extend in a spiraling formation. In  FIG. 8 , the shape of the spiraling part  241   b  obtained by performing step (b); i.e., the shape of the fixed scroll  24  is shown by the single-dashed line. In the iron casting  241  obtained in step (a), the dimension of the specified portion of the spiraling part  241   b  is greater than the dimension of the same portion after step (b) is performed (Mode B), similar to the iron casting  261  shown in  FIGS. 4 and 5 . 
     Specifically, in  FIG. 8 , the thickness d 13  of the portion  241   b   1  of the spiraling part  241   b  is greater than the thickness h 13  of the portion  241   b   1  after step (b) is performed. In other words, in the aforementioned Mode B, the portion  241   b   1  is used as the specified portion, and the thickness d 13  of the portion  241   b   1  is used as the dimension. 
     The portion  241   b   1  extends along the spiral from the end  2412  at the external periphery of the spiral up to a position  2413  that is different from the end  2411  at the center  9  of the spiral. 
     In  FIG. 8 , the portion  241   b   1  extends around the center  9  to a position located anywhere from a half circle (angle θ 2 =90° up to a full circle (angle θ 2 =180° from the end  2412 . The angle θ 2  is an angle formed by the direction in which the spiral extends from the end  2412  and the circumference of the center  9 , and  FIG. 8  shows a case in which θ 1  is between 90° and 180°. 
     By performing step (b) on the iron casting  241  obtained in step (a), a panel  24   a  is obtained from the fixed part  241   a , and a compression member  24   b  is obtained from the spiraling part  241   b.    
     According to this method for manufacturing a fixed scroll  24 , the heat capacity of the portion  241   b   1  of the spiraling part  241   b  can be increased, and the hardness of this same portion  241   b   1  can be increased, similar to the method for manufacturing an orbiting scroll  26  described in the first embodiment. Consequently, wear in the fixed scroll  24  can be reduced. 
     With this shape of the spiraling part  241   b  shown in  FIG. 8  in particular, it is possible to increase the hardness of the portion  241   b   1  positioned in the external periphery of the spiral in the spiraling part  241   b.    
     In the method for manufacturing a fixed scroll  24 , the shape shown in  FIG. 6  or  7  may be used for the spiraling part  241   b.    
     Fourth Embodiment 
     The following is a description of the orbiting scroll  26  obtained by either one of the manufacturing methods in the first and second embodiments. 
     As described in the first and second embodiments, the compression member  26   b  belonging to the orbiting scroll  26  obtained by the pertinent manufacturing methods; i.e., the spiraling part  261   b  after step (b) is performed, has a high hardness. 
     Consequently, in the portion near the external periphery in the compression member  26   b , the compression member  26   b  does not readily deform even if the ratio H/T of the height H of the compression member  26   b  from the panel  26   a  ( FIGS. 2 ,  3 , and  7 ) to the thickness T of the compression member  26   b  ( FIGS. 2 ,  3 , and  7 ) is 8.5 or greater. The orbiting scroll  26  can be reduced in size by designing the orbiting scroll  26  with this ratio H/T. 
     The orbiting scroll  26  manufactured by the method according to the first and second embodiments resists wear and deformation. Consequently, break-downs with the compression mechanism  15  can be minimized by using the orbiting scroll  26  as a scroll member of the compression mechanism  15 . 
     A compression member  24   b  having high strength is also obtained with the fixed scroll  24  obtained by the manufacturing method of the third embodiment. Consequently, the ratio H/T of the height H of the compression member  24   b  to the thickness T can be made to be 8.5 or greater. 
     The fixed scroll  24  resists wear and deformation. Consequently, break-downs with the compression mechanism  15  can be minimized by using the fixed scroll  24  as a scroll member of the compression mechanism  15 . 
     EXAMPLES 
     Structure of Scroll Compressor 
     The structure of the scroll compressor  1  will be described in greater detail using  FIG. 1 . In addition to the case  11  and the compression mechanism  15 , the scroll compressor  1  comprises an Oldham ring  2 , a fixed member  12 , a motor  16 , a crankshaft  17 , an intake pipe  19 , a discharge pipe  20 , and a bearing  60 . 
     The case  11  has a cylindrical shape and extends along the direction  91 . The Oldham ring  2 , the fixed member  12 , the motor  16 , the crankshaft  17 , and the bearing  60  are housed within the case  11 . 
     The motor  16  has a fixed element  51  and a rotary element  52 . The fixed element  51  is annular in shape and is fixed to an internal wall  11   a  of the case  11 . The rotary element  52  is provided to the internal periphery of the fixed element  51  and is made to face the fixed element  51  across an air gap. 
     The crankshaft  17  extends along the direction  91  and has a main shaft  17   a  and an eccentric part  17   b . The main shaft  17   a  is a portion that rotates around a rotational axis  90  and is connected to the rotary element  52 . The eccentric part  17   b  is a portion disposed unevenly with respect to the rotational axis  90 , and is connected to the top side of the main shaft  17   a . The lower end of the crankshaft  17  is slidably supported by the bearing  60 . 
     The fixed member  12  is specifically a housing in  FIG. 1 , and is fitted without any gaps into the internal wall  11   a  of the case  11 . The fixed member  12  is fitted into the internal wall  11   a  by, e.g., press fitting, shrink fitting, or another method. The fixed member  12  may be fitted into the internal wall  11   a  via a seal. 
     Since the fixed member  12  is fitted into the internal wall  11   a  without gaps, a space  28  positioned on the underside of the fixed member  12  and a space  29  positioned on the top side are partitioned without any gaps. Consequently, the fixed member  12  is capable of maintaining pressure differences that occur between the space  28  and the space  29 . The pressure in the space  28  is high, and the pressure in the space  29  is low. 
     A hollow  31  opened in the top side of the fixed member  12  is provided in the vicinity of the rotational axis  90 . The eccentric part  17   b  of the crankshaft  17  is accommodated within the hollow  31 . Furthermore, the fixed member  12  has a bearing  32  and a hole  33 . The bearing  32  supports the main shaft  17   a  while the main shaft  17   a  of the crankshaft  17  is in a state of being inserted through the hole  33 . 
     The surface on the top side of the fixed scroll  24  has a concavity. A space  45  enclosed by a portion  42  in this surface having the concavity is shut by a lid  44 . The lid  44  partitions two spaces of different pressures; i.e., the space  45  and the space  29  on the top side. 
     The orbiting scroll  26  also comprises a bearing  26   c . The bearing  26   c  is linked to the underside of the panel  26   a , and the bearing  26   c  slidably supports the eccentric part  17   b  of the crankshaft  17 . 
     &lt;Flow of Refrigerant&gt; 
     The flow of refrigerant through the scroll compressor  1  will be described using  FIG. 1 . In  FIG. 1 , the flow of refrigerant is depicted by arrows. Refrigerant is taken in through the intake pipe  19  and is led into the compression chamber (space  40 ) of the compression mechanism  15 . The refrigerant compressed by the compression chamber (space  40 ) is discharged out to the space  45  through a discharge hole  41  provided near the center of the fixed scroll  24 . Consequently, the pressure in the space  45  is high. Conversely, the pressure in the space  29  partitioned from the space  45  by the lid  44  remains low. 
     The refrigerant in the space  45  flows sequentially through a hole  46  provided in the fixed scroll  24  and a hole  48  provided in the fixed member  12 , and then flows into the space  28  below the fixed member  12 . The refrigerant in the space  28  is led into a gap  55  by a guiding plate  58 . The gap  55  is provided between the case  11  and part of the side surface of the fixed element  51 . 
     The refrigerant that has flowed through the gap  55  to the space below the motor  16  then flows through an air gap or a space  56  in the motor  16 , and then flows into the discharge pipe  20 . The space  56  is provided between the case  11  and another part of the side surface of the fixed element  51 . 
     INDUSTRIAL APPLICABILITY 
     The present invention can be widely applied to the field of scroll members, manufacturing methods thereof, compression mechanisms, and scroll compressors.