JP6027586B2 - Magnesium alloy die-casting wheel - Google Patents

Description

The present invention relates to a magnesium alloy die casting wheel.

  As in Patent Document 1, a magnesium alloy wheel is manufactured by die casting.

JP 2007-118684 A

  According to die casting, the production time can be shortened as compared with gravity casting and the like. However, when a magnesium alloy wheel is manufactured using die casting, it may be difficult to ensure casting quality. In particular, when the rim width is wide, it is difficult to uniformly fill the rim with the molten metal, which may make it difficult to ensure casting quality.

An object of the present invention is to provide a magnesium alloy die-casting wheel that has improved productivity by improving casting quality while shortening manufacturing time.

Magnesium alloy die casting wheel of the present invention, an axle insertion section axle insertion holes are formed to drive shaft is inserted, a spoke extending from the axle insertion portion in a radial direction of the central axis of said axle insertion hole A rim portion extending in the circumferential direction of the central axis and formed in an annular shape and connected to the spoke portion, and a connecting portion between the spoke portion and the rim portion, the connecting portion including the diameter The direction is closer to the axle insertion part than the inner peripheral surface of the rim part facing the axle insertion part, and the axial direction along the central axis is narrower than the formation range of the rim part. A bottom surface portion formed so as to intersect with a direction in which the spoke portion extends, and the bottom surface portion in the circumferential direction in the rim portion from both end portions in the circumferential direction in the bottom surface portion. From the first and second slope portions extending in a direction away from each other in the circumferential direction from the both ends to the axial direction in the bottom surface portion, and the bottom portion in the axial direction in the rim portion The third and fourth slopes extending in the direction away from each other in the axial direction from the part to the part separated from each other are such that the area of the cross section of the connecting part orthogonal to the radial direction is larger as the cross section near the rim part In addition, all of the four slope portions are formed so as to be recessed toward the rim portion and to be smoothly curved and extend toward the rim portion .

  The inventor has studied a method for improving the casting quality of the rim portion when a magnesium alloy wheel is manufactured by die casting. As a result, it has been found that the quality problem of the rim portion arises because it is difficult to distribute the molten metal uniformly. This is because it is difficult to improve the casting quality of the entire rim portion unless the molten metal reaches the rim portion uniformly.

  Further, as another phenomenon in which a quality problem occurs in the rim portion, it has been found that there is a possibility that a shrinkage nest is generated in the rim portion and air leaks therefrom. In die casting, there is a difference in the time from the injection of the molten metal to the solidification of the molten metal depending on the rim portion. A shrinkage nest may occur at a site where coagulation is slow.

  As a result of further research, it was found that such a shrinkage nest was likely to occur at the connection point between the rim and spoke. This is because when the molten metal flows from the spoke portion into the rim portion, the flow of the molten metal may be disturbed if the cross-sectional area changes suddenly at the connecting portion between the rim portion and the spoke portion. In the die casting of magnesium, which has a casting limit speed faster than that of aluminum die casting, the molten metal is flowed faster than in the case of aluminum in order to increase the productivity. On the other hand, if the casting speed is slowed down, magnesium solidifies before it is completely filled because the solidification speed is high.

  Therefore, the present inventor controls the flow of the molten metal by providing the bottom surface portion and the first to fourth slope portions as described above as a connection portion between the spoke portion and the rim portion extending from the axle insertion portion. I tried to suppress the shrinkage nest. That is, when flowing the molten metal from the spoke portion to the rim portion, the molten metal from the spoke portion is once received at the bottom surface portion and then flowed to the first to fourth slope portions. The bottom surface portion is formed so as to intersect with the spoke portion and to be narrower in the axial direction than the rim portion. Further, the first and second slope portions extend from both end portions of the bottom surface portion to the rim portion in a direction away from each other in the circumferential direction. Furthermore, the 3rd and 4th slope part is extended in the direction mutually spaced apart about an axial direction from the both ends of a bottom face part to a rim | limb part. That is, the first to fourth slope portions are formed so as to spread in both the circumferential direction and the axial direction from the spoke portion toward the rim portion. Therefore, the molten metal from the spoke part is received by the bottom part having a relatively small cross section perpendicular to the radial direction, and then spreads in both the circumferential direction and the axial direction on the first to fourth slope parts. Flows into the club. In the 1st-4th slope part, the area of the cross section of the connection part orthogonal to a radial direction becomes so large that it approaches a rim | limb part.

  As described above, when the molten metal flows from the spoke portion to the rim portion, the change in the cross section with respect to the flow can be moderated while controlling the flow direction at the connecting portion. For this reason, a molten metal can be spread uniformly from a spoke part to a rim | limb part through a connection part. Moreover, it can suppress that a disorder | damage | failure arises in the flow of a molten metal, and can suppress a shrinkage nest. By these, it is possible to improve the casting quality of the whole rim part and to improve productivity.

  Moreover, in this invention, the said spoke part is connected to the one end part and other end part of the said bottom face part about the said circumferential direction, respectively, and has two board parts extended in the said axial direction. preferable.

  According to this, the molten metal which flows through two board parts can be poured smoothly from the both ends of a bottom face part to the 1st and 2nd slope part.

  Moreover, in this invention, the said 1st and 2nd slope part may be symmetrical about the plane which passes along the center part of the said bottom face part about the said circumferential direction, and is orthogonal to the said circumferential direction.

  According to this, the molten metal from a spoke part can be poured equally into each of the 1st and 2nd slope part.

  Moreover, in this invention, the said 3rd and 4th slope part may be symmetrical about the plane which passes along the center part of the said bottom face part about the said axial direction, and is orthogonal to the said axial direction.

  According to this, the molten metal from a spoke part can be poured equally into each of the 3rd and 4th slope part.

  Moreover, in this invention, the said 1st and 2nd slope part may be asymmetric about the plane which passes along the center part of the said bottom face part about the said circumferential direction, and is orthogonal to the said circumferential direction.

  According to this, the shape of the first and second slope portions can be adjusted so as to control the flow of the melt asymmetrically in accordance with the position of the spoke portion in the circumferential direction and the like.

  Moreover, in this invention, the said 3rd and 4th slope part may be asymmetric about the plane which passes along the center part of the said bottom face part about the said axial direction, and is orthogonal to the said axial direction.

  According to this, the shape of the third and fourth slope portions can be adjusted so as to control the flow of the melt asymmetrically in accordance with the position of the spoke portion in the axial direction and the like.

  In the present invention, the axle insertion portion has a first recess that opens in one of the two directions along the axial direction, and an opening in the other direction of the two directions. It is preferable that the second recesses are formed so as to be arranged in at least one of the circumferential direction and the radial direction.

  According to this, it can reduce in weight efficiently by the 1st and 2nd recessed part which adjoins mutually.

  Moreover, in this invention, the said spoke part may be arrange | positioned in the center part of the said rim | limb part about the said axial direction.

  According to this, since the spoke part is arranged at the center of the rim part, the molten metal can be easily poured from the spoke part to the rim part.

1 is a side view of a motorcycle according to an embodiment of the present invention. Fig. 2 is a left side view of a wheel used for the motorcycle of Fig. 1. It is a perspective view of the wheel of FIG. It is a top view of the wheel of FIG. It is the VV line end view of FIG. FIG. 6A is an end view taken along the line VIa-VIa of FIG. FIG. 6B is an end view taken along the line BB in FIG. FIG. 6C is an end view taken along the line CC of FIG. Fig.7 (a) is the elements on larger scale of Fig.6 (a). FIG.7 (b) is the elements on larger scale of FIG.6 (b). FIG.7 (c) is a perspective view of the connection part seen from the axle shaft insertion part. FIG. 8A and FIG. 8B are cross-sectional views of a connecting portion with respect to a cut surface perpendicular to the radial direction and having different positions in the radial direction. It is a front view of the casting_mold | template used in the die-casting of a wheel. A broken line indicates a structure formed inside the mold. Fig.10 (a) is an end view of the connection part which concerns on a modification, Comprising: It is a figure corresponding to Fig.7 (a). FIG.10 (b) is an end elevation of the connection part which concerns on a modification, Comprising: It is a figure corresponding to FIG.7 (b). Fig.11 (a) is a perspective view of the connection part which concerns on another modification. FIG. 11B is an end view taken along line XIb-XIb in FIG. FIG.11 (c) is a perspective view of the connection part which concerns on another modification. FIG. 11C is an end view taken along line XId-XId of FIG.

Hereinafter, an embodiment of the present invention will be described by taking the motorcycle 1 as an example. The motorcycle 1 is provided with a wheel 100 that employs a magnesium alloy die-casting wheel according to the present invention.

  In the following description, the front-rear direction refers to the front-rear direction of the vehicle when viewed from a rider R seated on a rider seat 11 (described later) of the motorcycle 1. The left-right direction is the vehicle left-right direction (vehicle width direction) when viewed from the rider R seated on the rider seat 11. An arrow F direction and an arrow B direction in the drawing represent the front and the rear. The arrow L direction and the arrow R direction in the figure represent the right side and the left side. In FIG. 2 and subsequent figures, the front, rear, left, right and up directions correspond to directions when the wheel 100 is provided in the motorcycle 1.

  As shown in FIG. 1, the motorcycle 1 includes a front wheel 2, a rear wheel 3, a body frame 4, and a rider seat 11. A handle unit 9 is provided at a portion of the body frame 4 in front of the rider seat 11. A grip 9R is provided at the right end of the handle unit 9, and a grip 9L is provided at the left end. FIG. 1 shows only the grip 9L. The grip 9R is disposed on the opposite side of the grip 9L in the left-right direction. The grip 9R is an accelerator grip. A brake lever is attached near the grip 9R. A clutch lever 10 is attached near the grip 9L. An upper end portion of the front fork 7 is fixed to the handle unit 9. An axle 17 extending along the left-right direction is fixed to the lower end portion of the front fork 7. The front wheel 2 is supported on the axle 17. The front wheel 2 includes a wheel 100 and a tire 2 a attached to the outer periphery of the wheel 100.

  A front end portion of the swing arm 12 is swingably supported at the lower portion of the vehicle body frame 4. The rear end portion of the swing arm 12 supports the rear wheel 3. The part different from the swing center of the swing arm 12 and the body frame 4 are connected via a rear suspension that absorbs an impact in the vertical direction.

  The vehicle body frame 4 supports a water-cooled engine 13. The engine 13 may be air-cooled. The body frame 4 may directly support the engine 13 or may indirectly support it through another member. A fuel tank 14 is disposed above the engine 13.

  A transmission having a plurality of speed change gears is disposed behind the engine 13. The driving force of the engine 13 is transmitted to the rear wheel 3 through the transmission and the chain 26. On the left side of the transmission, a shift pedal 24 for switching the transmission gear is provided. Footrests 23 are provided on both sides of the body frame 4 and slightly in front of the rear wheel 3. The rider R puts both feet on the footrest 23 while riding.

  A front cowl 15 is disposed above the front wheel 2 and in front of the grips 9R and 9L. A meter unit 16 is disposed between the front cowl 15 and the grips 9R and 9L in the front-rear direction. The meter unit 16 is arranged to be inclined with respect to the front-rear direction and the vertical direction so that the display surface faces rearward and upward. On the display surface, vehicle speed, engine speed, vehicle state, travel distance, clock, measurement time, and the like are displayed.

Hereinafter, the wheel 100 employing the magnesium alloy die-casting wheel according to the present invention will be described in more detail with reference to FIGS. The wheel 100 is made of a magnesium alloy. The magnesium alloy here indicates an alloy containing 4.0% by weight or more of magnesium. The wheel 100 is integrally cast by a die casting method. Details of die casting will be described later.

  2 to 4, the wheel 100 includes an axle insertion portion 110 in which an axle insertion hole 111 a into which the axle 17 is inserted is formed, and a radial direction (from the axle insertion portion 110 to the central axis of the axle insertion hole 111 a ( Hereinafter, it has a plurality of spoke portions 150 extending simply in the “radial direction” and a rim portion 140 connected to the spoke portion 150. The axial direction along the central axis of the axle insertion hole 111a is parallel to the left-right direction. In the present specification, “extending in the radial direction” is not limited to the case of extending along a strict radial direction (for example, the radial direction shown in FIG. 2) passing through the central axis of the axle insertion hole 111a. The case of extending from the axle insertion portion 110 toward the rim portion 140 along the direction inclined with respect to the strict radial direction is also included in “extending in the radial direction”. That is, the case of extending from the axle insertion portion 110 toward the rim portion 140 along a straight line that does not pass through the central axis of the axle insertion hole 111a is also included in “extending in the radial direction”.

  As shown in FIG. 2, a boss portion 111 having an axle insertion hole 111a formed therein is provided at the center of the axle insertion portion 110. The boss 111 has a cylindrical shape. The axle insertion portion 110 is formed with five bolt holes 112 for fixing the brake disc bracket around the boss portion 111. The number of bolt holes may be three to six.

  The axle insertion portion 110 has a disk-like schematic shape having five protruding portions 110 a protruding in the radial direction toward the rim portion 140. The five protruding portions 110a are connected to the spoke portion 150. As shown in FIG. 5, the protrusion 110 a is formed with a recess 113 that opens to the left and a recess 114 that opens to the right. As for the recessed part 113, the width | variety about the circumferential direction is so large that the left part is. The width of the concave portion 114 in the circumferential direction is larger toward the right side.

  As shown in FIGS. 2 and 3, two spoke parts 150 extend radially from each protrusion part 110 a toward the rim part 140. A region (a region surrounded by a two-dot chain line Q in FIG. 2) composed of the protruding portion 110 a and the two spoke portions 150 connected thereto is formed in a Y shape from the boss portion 111 toward the rim portion 140. ing. Hereinafter, this region is referred to as region Q. A total of five regions Q are formed in the wheel 100. These regions Q are arranged at equal intervals in the circumferential direction and at the same position in the radial direction. In the region Q, the surface portion facing leftward is substantially symmetrical with respect to the straight line P along the radial direction shown in FIG. In the region Q, an edge portion 150a (a portion surrounded by a two-dot chain line) that defines a space having a schematic shape of a rounded triangle in FIG. 2 is formed between the two spoke portions 150. Between the spoke portions 150 of two adjacent regions Q, an edge portion 150b that defines a space having a schematic shape of a polygon with rounded corners in FIG. 2 is formed. As described above, the ten spoke portions 150 as a whole are arranged at intervals in the circumferential direction of the central axis of the axle insertion hole 111a (hereinafter simply referred to as “circumferential direction”).

  As shown in FIGS. 2 and 6 (a) to 6 (c), each spoke portion 150 includes two plate portions 151 extending from the protruding portion 110a toward the rim portion 140, and two plate portions. 151 includes a plate portion 152 extending from one of the two plate portions 151 to the other. Each plate part 151 extends along the left-right direction. The plate portion 152 extends along the front-rear direction and extends from the protruding portion 110 a toward the rim portion 140. The plate portion 152 is disposed at a position away from both ends of the plate portion 151 in the left-right direction.

  The rim portion 140 extends in the circumferential direction and is formed in an annular shape. The width W in the left-right direction of the rim portion 140 is relatively large. For example, it is about 125 mm (5 inches). The width W may be other sizes. Both end portions 143 in the left-right direction of the rim portion 140 protrude in a direction opposite to the direction toward the axle insertion portion 110. A thickness t1 of the rim portion 140 is, for example, 3.8 mm to 4.5 mm. The thickness t1 may be other sizes. The rim portion 140 is a surface that is far from the axle insertion portion 110 in the radial direction, and has a range (a range indicated by an arrow w <b> 1 in FIG. 6A) from one tip of the both ends 143 to the other tip. A tire 2a is attached to the surface. Hereinafter, this surface is referred to as a mounting surface 140a. In the rim portion 140, a surface on the opposite side in the radial direction and having a range (a range indicated by an arrow w <b> 2 in FIG. 6A) from one root of the both end portions 143 to the other root Let it be surface 140b. The inner peripheral surface 140b faces the axle insertion portion 110. Each spoke 150 is connected to the center in the left-right direction of the inner peripheral surface 140b.

  By the way, if a magnesium alloy wheel is manufactured by die casting, the manufacturing time can be shortened as compared with the case of manufacturing by gravity casting or the like. Therefore, it is expected that productivity can be improved. However, when a magnesium alloy wheel is manufactured by die casting, it has been confirmed by the present inventor that the rate of deterioration of the quality of the rim portion may be relatively high. Since a product in which a defect has occurred is not targeted for shipment, an increase in the rate of occurrence of a defect leads to a decrease in production volume. Therefore, when the quality of the rim portion is lowered, there is a possibility that productivity cannot be improved despite using die casting.

  Therefore, when the present inventor researched a method for improving the casting quality of the rim part, the quality problem of the rim part arises because it is difficult to spread the molten metal evenly on the rim part during die casting. I understood. This is because it is difficult to improve the casting quality of the entire rim portion unless the molten metal reaches the rim portion evenly.

  Further, as another phenomenon in which a quality problem occurs in the rim portion, it has been found that there is a possibility that a shrinkage nest is generated in the rim portion and air leaks therefrom. In die casting, there is a difference in the time from the injection of the molten metal to the solidification of the molten metal depending on the rim portion. A shrinkage nest may occur at a site where coagulation is slow.

  As a result of further research, it was found that such a shrinkage nest was likely to occur at the connection point between the rim and spoke. This is because when the molten metal flows from the spoke portion into the rim portion, the flow of the molten metal may be disturbed if the cross-sectional area changes suddenly at the connecting portion between the rim portion and the spoke portion. In the die casting of magnesium, which has a casting limit speed faster than that of aluminum die casting, the molten metal is flowed faster than in the case of aluminum in order to increase the productivity. On the other hand, if the casting speed is slowed down, magnesium solidifies before it is completely filled because the solidification speed is high.

  Therefore, in the present embodiment, in order to improve the casting quality of the rim portion, the following connecting portion 160 that connects them is provided between the rim portion 140 and the spoke portion 150. Hereinafter, the connecting portion 160 will be described with reference to FIGS. 6A, 6 </ b> B, 7 </ b> A to 7 </ b> C, and 8.

  The connecting part 160 is provided between the rim part 140 and the spoke part 150. The connecting portion 160 has one bottom surface portion 161, two slope portions 162, and two slope portions 163. The bottom surface portion 161 is arranged at a position closer to the axle insertion portion 110 in the radial direction than the inner peripheral surface 140b of the rim portion 140. The bottom surface portion 161 is formed in a range narrower than the inner peripheral surface 140b of the rim portion 140 in the left-right direction. The bottom surface portion 161 extends in the left-right direction so as to intersect the direction (radial direction) in which the spoke portion 150 extends. The thickness t2 of the bottom surface portion 161 is preferably less than the thickness t1 of the rim portion 140. For example, the thickness t2 is in the range of 3.8 to 4.5 mm. The thickness t2 may be other sizes. In the bottom surface portion 161, the surface 161a facing the axle insertion portion 110 is formed substantially flat along a direction intersecting the radial direction. The surface 161a has a substantially rectangular shape. Two plates 151 and 152 constituting the spoke 150 are connected to the surface 161a. Regions T1, T2, and S in FIG. 7C indicate regions where the two plate portions 151 and the plate portion 152 are connected. The two plate portions 151 are connected to both end portions in the circumferential direction of the surface 161a. The plate part 152 is connected to the center part in the left-right direction of the surface 161a. The width V in the left-right direction of the surface 161a is preferably 5% or more and less than 30% of the width W of the rim portion 140. The width V may be other sizes.

  The two slope portions 162 extend from both end portions in the circumferential direction of the bottom surface portion 161 to the rim portion 140. Each inclined surface portion 162 is connected to an end portion in the circumferential direction of the bottom surface portion 161 at one end portion 162a. The other end portion 162b of each slope portion 162 is connected to the rim portion 140 at a position separated from the bottom surface portion 161 in the circumferential direction. The two slope portions 162 extend from the bottom surface portion 161 to the rim portion 140 in a direction away from each other in the circumferential direction. That is, the two inclined surface portions 162 extend so that the distance from each other increases in the circumferential direction as the portion is closer to the rim portion 140. Thus, the two slope portions 162 are formed so as to expand in the circumferential direction from the spoke portion 150 toward the rim portion 140. The two slope portions 162 are symmetric with respect to the plane C2 in FIG. The plane C2 passes through the central portion of the bottom surface portion 161 in the circumferential direction and is orthogonal to the circumferential direction. The surface 162c of the slope portion 162 forms a slope that is smoothly curved in an R shape. The surface 162c is smoothly connected to the surface 151a of the plate portion 151 of the spoke portion 150, and is also smoothly connected to the inner peripheral surface 140b of the rim portion 140.

  The two slope portions 163 extend from both end portions of the bottom surface portion 161 in the left-right direction to the rim portion 140. Each inclined surface portion 163 is connected to an end portion of the bottom surface portion 161 in the left-right direction at one end portion 163a. The magnitude θ of the acute angle between the one end portion 163a of the slope portion 163 and the bottom surface portion 161 may be in the range of 5 ° to 45 °. In addition, (theta) may be magnitude | sizes other than this. The other end portion 163b of each slope portion 163 is connected to the rim portion 140 at a position separated from the bottom surface portion 161 in the left-right direction. The two slope portions 163 extend from the bottom surface portion 161 to the rim portion 140 in a direction away from each other in the left-right direction. That is, the two slope portions 163 extend so that the distance between the two slope portions 163 increases in the left-right direction as the portion is closer to the rim portion 140. Thus, the two slope portions 163 are formed so as to expand in the axial direction from the spoke portion 150 toward the rim portion 140. The two slope portions 163 are symmetric with respect to the plane C1 in FIG. The plane C1 passes through the center portion of the bottom surface portion 161 in the left-right direction and is orthogonal to the left-right direction. A surface 163c of the inclined surface portion 163 forms an inclined surface that is smoothly curved in an R shape. The surface 163c is smoothly connected to both end surfaces 151b of the plate portion 151 of the spoke portion 150 in the left-right direction, and is also smoothly connected to the inner peripheral surface 140b of the rim portion 140.

  When viewed from the axle insertion portion 110, the connecting portion 160 has a general shape of a truncated pyramid having the surface 161a as a top surface and the surfaces 162c and 163c as wall surfaces, as shown in FIG. 7C. The surface 162c is curved so as to be recessed in the circumferential direction and the surface 163c is recessed in the left-right direction. Further, when viewed from the outside of the rim portion 140 in the radial direction, the connecting portion 160 has a generally truncated pyramid shape from the outer peripheral surface 140a of the rim portion 140 toward the axle insertion portion 110 as shown in FIGS. It appears as a recess 160a that is recessed to have. In the connecting portion 160, the area composed of the two slope portions 162 and the two slope portions 163 is such that the area of the cross section perpendicular to the radial direction becomes larger as the rim portion 140 is closer (away from the axle insertion portion 110). It has a shape. FIG. 8A and FIG. 8B both show a cross section of the connecting portion 160 in the direction orthogonal to the radial direction. The cross section of FIG. 8B is a cross section at a position closer to the rim portion 140 than the cross section of FIG. The area of the cross section of FIG. 8B is larger than the area of the cross section of FIG.

  Hereinafter, the casting method of the wheel 100 of this embodiment will be described with reference to FIG. In this casting method, die casting is performed using the mold 200 shown in FIG. The mold 200 is formed in a shape corresponding to the shape of the wheel 100 inside the mold 201. An injection path 202 for injecting molten magnesium alloy is connected to a region 200 a corresponding to the axle insertion portion 110 in the mold 200. That is, in the wheel 100 of the present embodiment, a molten metal inlet is set in the axle insertion portion 110. A piston 205 for applying pressure to the molten metal, a rod, and a cylinder are connected to the injection path 202 via a sleeve. Around the mold 200, an overflow 203 is formed for discharging a portion of the molten metal poured into the mold 200 having a poor internal quality. The overflow 203 is connected to a region 200 c corresponding to the rim portion 140 in the mold 200. The overflow 203 is disposed between the regions 200b corresponding to the spokes 150 in the mold 200 in the direction corresponding to the circumferential direction of the wheel 100. The overflow 203 is further connected to the discharge path 204. The discharge path 204 is a flow path for discharging the air in the mold and the molten metal having poor internal quality to the outside of the mold 201.

  A thick black arrow in FIG. 9 shows an example of the flow of the molten metal. After the molten metal is injected into the piston 205, pressure is applied to the molten metal by the piston 205. Thereby, the molten metal is injected into the mold 200 from the piston 205 through the injection path 202. The molten metal flows in the mold 200 from the region 200a to the region 200b. In the region 200b, the molten metal passes through three paths corresponding to the two plate portions 151 and the one plate portion 152. Then, the molten metal flows from the region 200b into the region 200x corresponding to the connecting portion 160. In the region 200x, the molten metal from the region 200b is temporarily received in the region corresponding to the bottom surface portion 161. The molten metal from the path corresponding to the plate portion 151 flows into a region corresponding to the end portion in the circumferential direction of the bottom surface portion 161. The molten metal from the path corresponding to the plate portion 152 flows into a region corresponding to the end portion in the left-right direction of the bottom surface portion 161. And the molten metal which flowed into the area | region corresponding to the bottom face part 161 flows further toward the area | region 200c along the area | region corresponding to the slope parts 162 and 163 from there. In the region 200 c, the molten metal branches in two directions in the circumferential direction and is discharged from the overflow 203. As a result, air or the like existing in the mold 200 is discharged together with the molten metal.

  The speed at which the molten metal flows in die casting is faster than other casting methods such as gravity casting. In addition, the magnesium alloy has a shorter solidification time than the aluminum alloy, but it is difficult for seizure to occur on the mold, so that the molten metal can flow at a high speed. For this reason, also in this embodiment, compared with the case where an aluminum alloy is used, a molten metal is poured at high speed. The semi-finished product after die casting is appropriately subjected to heat treatment.

  The following differences occur in the composition of the materials in the region 200a, the region 200b, and the region 200c after such die casting. First, relatively large crystal grains are formed in the region 200a close to the injection path 202 when the high-temperature pouring is cooled and solidified. On the other hand, in the region 200b and the region 200c apart from the pouring path 202, the temperature of the pouring when it reaches is low. For this reason, in these regions, relatively small crystal grains are formed by cooling and solidifying the molten metal having a temperature lower than that of the region 200a. Since the temperature of the poured hot water when reaching the position farther from the injection path 202 becomes lower, the crystal grains tend to be formed smaller. For example, the average crystal grain size in the region 200a is larger than the average crystal grain size in the region 200b and the region 200c.

  According to the present embodiment described above, by providing the bottom surface portion 161 and the slope portions 162 and 163 as the connecting portion 160 between the spoke portion 150 and the rim portion 140, the flow of the molten metal is controlled when performing die casting. To reduce shrinkage.

  That is, in the mold 200, when the molten metal flows from the region 200b corresponding to the spoke portion 150 to the region 200c corresponding to the rim portion 140, the molten metal from the region 200b is temporarily received in the region corresponding to the bottom surface portion 161 in the region 200x. Then, the molten metal was allowed to flow from there to a region corresponding to the slope portions 162 and 163. In the wheel 100, the bottom surface portion 161 intersects with the spoke portion 150 and is formed to be narrower in the left-right direction than the rim portion 140. Further, the two slope portions 162 extend from both end portions of the bottom surface portion 161 to the rim portion 140 in a direction away from each other in the circumferential direction. Further, the two inclined surface portions 163 extend from both end portions of the bottom surface portion 161 to the rim portion 140 in directions away from each other in the axial direction. That is, the slope portions 162 and 163 are formed so as to spread in both the circumferential direction and the axial direction from the spoke portion 150 toward the rim portion 140.

  Therefore, the molten metal from the region 200b is received by the region corresponding to the bottom surface portion 161 having a relatively small cross-sectional area perpendicular to the radial direction, and then in the region corresponding to the slope portions 162 and 162 in the circumferential direction and the axial direction. It flows into the region 200c while controlling the flow direction so as to spread in both directions. In the regions corresponding to the slope portions 162 and 163, the cross-sectional area of the region 200x with respect to the cross section along the direction orthogonal to the radial direction increases as the region 200c is approached. That is, the flow path of the molten metal in the region corresponding to the slope portions 162 and 163 gradually increases in cross-sectional area as it approaches the region 200c.

  As described above, in the mold 200, when the molten metal flows from the region 200b to the region 200c, the change in the cross section with respect to the flow can be moderated while controlling the flow direction in the region 200x. For this reason, the molten metal can be made to flow evenly through the region 200x at the inlet from the region 200b to the region 200c. As a result, the molten metal can be uniformly distributed in the region 200c. Moreover, it can suppress that a disorder | damage | failure arises in the flow of a molten metal, and can suppress a shrinkage nest. Thus, it is possible to improve the casting quality of the entire rim portion 140 and improve productivity.

  Moreover, in this embodiment, the two board parts 151 of the spoke part 150 are connected to the both ends of the bottom face part 161 about the circumferential direction. Therefore, in the mold 200, the molten metal flowing through the region corresponding to the two plate portions 151 can be smoothly poured from the both end portions of the region corresponding to the bottom surface portion 161 to the region corresponding to the slope portions 162 and 163. Furthermore, the surfaces 162c and 163c of the slope portions 162 and 163 are smoothly connected to the surface 151a of the plate portion 151, respectively. Therefore, the molten metal smoothly flows from the region corresponding to the plate portion 151 to each region corresponding to the slope portions 162 and 163. Furthermore, the surfaces 162c and 163c are smoothly connected to the inner peripheral surface 140b of the rim portion 140. For this reason, the molten metal smoothly flows into the region 200c from the regions corresponding to the slope portions 162 and 163.

  In the present embodiment, the two slope portions 162 are symmetric with respect to the plane C2. Therefore, the molten metal from the region 200b can be evenly poured into each of the regions corresponding to the two slope portions 162.

  In the present embodiment, the two slope portions 163 are symmetric with respect to the plane C1. Therefore, the molten metal from the region 200b can be evenly poured into each of the regions corresponding to the two slope portions 163.

  In the present embodiment, recesses 113 and 114 that are adjacent to each other in the circumferential direction are formed. Therefore, the axle insertion part 110 can be reduced in weight efficiently. Moreover, the recessed part 113 has spread toward the left, and the recessed part 114 has spread toward the right. For this reason, when using a pair of metal mold | die about the left-right direction in the case of die casting, the draft is formed in both the recessed parts 113 and 114. FIG. Therefore, it is possible to reduce the weight while facilitating release.

  Moreover, in this embodiment, the spoke part 150 is arrange | positioned in the center part of the rim | limb part 140 about the left-right direction. Therefore, it is easy to pour the molten metal evenly in the left-right direction from the region 200b to the region 200c.

  Further, the bottom surface portion 161 of the present embodiment is configured such that the thickness t2 is smaller than the thickness t1 of the rim portion 140, whereby the casting quality is improved as follows. In the region corresponding to the bottom surface portion 161, the die is easily heated by the direct hit of the molten metal from the region 200b during die casting. Therefore, the region corresponding to the bottom surface portion 161 is less likely to solidify the molten metal than the other regions. On the other hand, as described above, by making the thickness t2 smaller than the thickness t1, it is easy to match the timing at which the region corresponding to the bottom surface portion 161 is solidified with the timing at which the region corresponding to the rim portion 140 is solidified. Thereby, a shrinkage nest can be suppressed and, therefore, air leakage can be suppressed.

  The preferred embodiments of the present invention have been described above. However, the present invention is not limited to the above-described embodiments, and various modifications can be made as long as they are described in the claims. Moreover, the above-mentioned embodiment and the modifications described below can be implemented in combination with each other. In the present specification, the term “preferable” is non-exclusive, and means “preferably, but not limited to”. Further, in the present specification, the term “... may” is non-exclusive, and means “... may be, but is not limited to”. .

  For example, in the connecting portion 160 of the above-described embodiment, the two slope portions 162 are symmetric with respect to the plane C2, and the two slope portions 163 are symmetric with respect to the plane C1. However, instead of such a highly symmetric connecting portion 160, a connecting portion in which the slope portion is formed asymmetrically may be employed.

  The connecting portion 260 shown in FIGS. 10A and 10B is an example of such an asymmetric connecting portion. The connecting portion 260 has a bottom surface portion 261 connected to the spoke portion 150, and slope portions 262 to 265 extending from the bottom surface portion 261 to the rim portion 140. The slope portions 262 and 263 extend while being curved from both ends of the bottom surface portion 261 in the circumferential direction to a portion of the rim portion 140 that is separated from the bottom surface portion 261 in the circumferential direction. The slope portions 262 and 263 are spaced apart from each other in the circumferential direction as the portion closer to the rim portion 140 in the radial direction. The slope portions 262 and 263 are asymmetric with respect to the plane C2. The plane C2 passes through the central portion of the bottom surface portion 261 in the circumferential direction and is orthogonal to the circumferential direction. The slope portions 264 and 265 extend while being curved from both end portions of the bottom surface portion 261 in the left-right direction to a portion separated from the bottom surface portion 261 in the left-right direction in the rim portion 140. The slope portions 264 and 265 are separated from each other in the left-right direction as the portion closer to the rim portion 140 in the radial direction. The slope portions 264 and 265 are asymmetric with respect to the plane C1. The plane C1 passes through the center of the bottom surface portion 261 in the left-right direction and is orthogonal to the left-right direction. The connecting portion 260 is configured so that the area of the cross section perpendicular to the radial direction increases in the region of the slope portions 262 to 265 as it approaches the rim portion 140.

  An asymmetrical connection portion such as the connection portion 260 is used in die casting when the molten metal from the region of the spoke portion 150 is rather unevenly flowed into the region of the rim portion 140. The asymmetrical connecting portion such as the connecting portion 260 is more uniform in the molten metal inlet to the rim portion 140 when the molten metal flow is controlled to be rather uneven. It may be adopted when it can be distributed. Such a case may occur depending on the connection mode between the spoke part 150 and the rim part 140. For example, the connection position of the spoke part 150 to the rim part 140 is biased in the circumferential direction or the left-right direction, or the number of connection parts of the spoke part 150 is biased depending on the location. . Since the slope portions 262 and 263 are formed asymmetrically with each other as described above, the flow of the molten metal can be controlled asymmetrically according to the position of the spoke portion 150 in the circumferential direction. Further, since the slope portions 264 and 265 are formed asymmetrically with each other as described above, the flow of the molten metal can be controlled asymmetrically according to the position of the spoke portion 150 in the axial direction.

  Moreover, in the connection part 160 of the above-mentioned embodiment, the surface 161a of the bottom face part 161 has a substantially rectangular shape. However, a connecting portion having a shape other than a rectangular bottom surface portion may be used. Fig.11 (a) and FIG.11 (b) show an example of such a connection part. 11A and 11B includes a bottom surface portion 361 having a hexagonal approximate shape, two inclined surface portions 362 extending from the bottom surface portion 361 to the rim portion, and two inclined surface portions 363. And have. The two inclined surface portions 362 extend while curving from both end portions of the bottom surface portion 361 in the circumferential direction to a portion separated from the bottom surface portion 361 in the circumferential direction in the rim portion. The two inclined surface portions 362 are separated from each other in the circumferential direction as a portion closer to the rim portion in the radial direction. The two slope portions 362 are symmetric about a plane that includes the axis C4 and is orthogonal to the circumferential direction. The axis C4 passes through the central portion of the bottom surface portion 361 in the circumferential direction and is orthogonal to the circumferential direction. The two inclined surface portions 363 extend while being curved from both end portions of the bottom surface portion 361 in the left-right direction to portions separated from the bottom surface portion 361 in the left-right direction in the rim portion. The two slope portions 363 are separated from each other in the left-right direction as the portion closer to the rim portion in the radial direction. The two slope portions 363 are symmetric with respect to a plane including the axis C3 and orthogonal to the left-right direction. The axis C3 passes through the center portion of the bottom surface portion 361 in the left-right direction and is orthogonal to the left-right direction.

  FIG.11 (c) and FIG.11 (d) show another example of the connection part which a bottom face part has shapes other than a rectangle. 11 (c) and 11 (d) includes a bottom surface portion 461 having an elliptical approximate shape, two inclined surface portions 462 and two inclined surface portions 463 extending from the bottom surface portion 461 to the rim portion. And have. The slope portions 462 and 463 have their boundaries defined by the two-dot chain line curve in FIG. The slope portions 462 and 463 are smoothly connected to each other in the two-dot chain line curve, unlike the slope portions 162 and 163 described above. Thus, the case where adjacent slope portions are smoothly connected to each other is also included in the scope of the present invention. In this case, like the two slope portions 462, two slope portions connected to both ends of the bottom surface portion in the circumferential direction correspond to the first and second slope portions of the present invention. Further, like the two slope portions 463, two slope portions connected to both ends of the bottom surface portion in the left-right direction correspond to the third and fourth slope portions of the present invention.

  The two slope portions 462 extend while being curved from both end portions of the bottom surface portion 461 in the circumferential direction to a portion separated from the bottom surface portion 461 in the circumferential direction in the rim portion. The two slope portions 462 are separated from each other in the circumferential direction as the portion closer to the rim portion in the radial direction. The two slope portions 462 are symmetric about a plane that includes the axis C4 and is orthogonal to the circumferential direction. The axis C4 passes through the central portion of the bottom surface portion 461 in the circumferential direction and is orthogonal to the circumferential direction. The two slope portions 463 extend while being curved from both end portions of the bottom surface portion 461 in the left-right direction to a portion separated from the bottom surface portion 461 in the left-right direction in the rim portion. The two slope portions 463 are separated from each other in the left-right direction as the portion closer to the rim portion in the radial direction. The two slope portions 463 are symmetric with respect to a plane including the axis C3 and orthogonal to the left-right direction. The axis C3 passes through the center portion of the bottom surface portion 461 in the left-right direction and is orthogonal to the left-right direction.

  Further, the bottom surface portion may be formed in various polygonal shapes such as an octagonal shape and a decagonal shape in addition to the ellipse and the hexagonal shape in the connecting portions 360 and 460, and may be formed in a circular shape. Moreover, you may form in other various shapes.

  Moreover, in the above-mentioned embodiment, the surface 151a of the plate part 151 of the spoke part 150 and the surface 162c of the slope part 162 of the connection part 160 are smoothly connected (refer FIG.7 (b)). That is, the plate portion 151 is disposed so as to contact the edge in the circumferential direction on the surface 161 a of the bottom surface portion 161. However, the plate portion 151 may be disposed at a position away from the edge in the circumferential direction on the surface 161a. Such a configuration is also within the scope of “a plate portion connected to one end portion and the other end portion of the bottom surface portion in the circumferential direction” in the present invention. However, even in this case, the plate portion 151 is preferably arranged at a position close to the edge in the circumferential direction on the surface 161a. For example, it is preferable that the plate portion 151 is disposed at a position closer to the end edge than the center portion of the surface 161a in the circumferential direction. As a result, during die casting, the molten metal smoothly flows from the region corresponding to the plate portion 151 to the region corresponding to the slope portion 162.

  In the above-described embodiment, the surface 161a of the bottom surface portion 161 of the connecting portion 160 is formed flat. However, as long as the bottom surface portion intersects the direction in which the spoke portion extends, the surface of the bottom surface portion may be curved, or irregularities may be formed on the surface.

  In the above-described embodiment, the spoke part 150 is disposed at the center of the rim part 140 in the left-right direction. However, the present invention may be applied to a wheel in which the spoke part is arranged on the left or right side of the center part of the rim part in the left-right direction.

  Moreover, when the connection part 160 of the above-mentioned embodiment is seen from the axle shaft insertion part 110, the surfaces 162c and 163c are curved in a concave shape in the circumferential direction and the left-right direction. However, instead of such a connecting portion 160, there is a connecting portion in which the surface of the slope portion is not curved and is formed flat, or a connecting portion in which the surface of the slope portion is curved convexly in the circumferential direction and the left-right direction. It may be adopted.

  In the above-described embodiment, the axle insertion portion 110 is formed such that the concave portion 113 that opens toward the left and the concave portion 114 that opens toward the right are aligned in the circumferential direction. Such recesses may be formed so as to be aligned in the radial direction. That is, the concave portion opened toward the left side and the concave portion opened toward the right side may be formed to be aligned in the radial direction. These recesses may be formed in place of the recesses 113 and 114, or may be formed in addition to the recesses 113 and 114.

  In this specification, “X extends in the Y direction” indicates that X exists continuously in the Y direction. Also, “X extends from Y1 to Y2” indicates that X exists continuously from Y1 to Y2.

  Further, in this specification, “extending in the radial direction” is not limited to the case of extending along a strict radial direction (for example, the radial direction shown in FIG. 2) passing through the central axis of the axle insertion hole 111a. The case of extending from the axle insertion portion 110 toward the rim portion 140 along the direction inclined with respect to the strict radial direction is also included in “extending in the radial direction”. That is, the case of extending from the axle insertion portion 110 toward the rim portion 140 along a straight line that does not pass through the central axis of the axle insertion hole 111a is also included in “extending in the radial direction”.

  A vehicle that can employ the wheel 100 according to the present embodiment is not limited to the motorcycle 1 described above. The wheel 100 may be employed in other types of motorcycles such as an off-road type, a scooter type, and a moped type. The wheel 100 may be used for a straddle-type vehicle other than a motorcycle such as a three-wheeled vehicle or a four-wheeled buggy (ATV: All Terrain Vehicle). Furthermore, the wheel which concerns on this invention may be employ | adopted as the wheel of a motor vehicle.

DESCRIPTION OF SYMBOLS 1 Motorcycle 100 Wheel 110 Axle insertion part 111a Axle insertion hole 140 Rim part 140b Rim part inner peripheral surface 150 Spoke part 151 Plate part 160 Connection part 161 Bottom face part 162 Slope part 163 Slope part 200 Mold 260 Connection part 261 Bottom part 262 Slope portion 263 Slope portion 264 Slope portion 265 Slope portion 360 Connection portion 361 Bottom portion 362 Slope portion 363 Slope portion 460 Connection portion 461 Bottom portion 462 Slope portion 463 Slope portion

Claims (8)

And the axle insertion section axle insertion holes vehicle shaft is inserted is formed,
A spoke portion extending in a radial direction of a central axis of the axle insertion hole from the axle insertion portion;
A rim portion extending in the circumferential direction of the central axis and formed in an annular shape and connected to the spoke portion;
The spoke portion and the connecting portion of the rim portion,
In the connecting part,
The radial direction is closer to the axle insertion portion than the inner peripheral surface of the rim portion facing the axle insertion portion, and the axial direction along the central axis is narrower than the formation range of the rim portion. In the range, a bottom portion formed so as to intersect the direction in which the spoke portion extends is formed,
First and second slope portions extending in directions away from each other in the circumferential direction from both end portions in the circumferential direction in the bottom surface portion to a portion separated from the bottom surface portion in the circumferential direction in the rim portion; Third and fourth inclined surface portions extending in directions away from each other in the axial direction from both end portions in the axial direction in the bottom surface portion to portions spaced from the bottom surface portion in the axial direction in the rim portion. the Ri area of the cross section of the connecting part name large enough cross-section closer to the rim, and the rim while smoothly curved recessed with any of four inclined surface portion toward the rim portion that is perpendicular to the radial direction A die-casting wheel made of a magnesium alloy, characterized in that it is formed to extend toward the part . The said spoke part is respectively connected to the one end part and other end part of the said bottom face part about the said circumferential direction, and has the two board parts extended in the said axial direction. A die-casting wheel made of the described magnesium alloy. The said 1st and 2nd slope part is a plane which passes along the center part of the said bottom face part about the said circumferential direction, Comprising: It is symmetrical about the plane orthogonal to the said circumferential direction. Die-casting wheel made of magnesium alloy. The said 3rd and 4th slope part is a plane which passes along the center part of the said bottom face part about the said axial direction, Comprising: It is symmetrical about the plane orthogonal to the said axial direction. A magnesium alloy die-casting wheel according to claim 1. The said 1st and 2nd slope part is a plane which passes along the center part of the said bottom face part about the said circumferential direction, Comprising: It is asymmetric about the plane orthogonal to the said circumferential direction. A die-casting wheel made of a magnesium alloy as described in 1. The said 3rd and 4th slope part is a plane which passes along the center part of the said bottom face part about the said axial direction, Comprising: It is asymmetric about the plane orthogonal to the said axial direction. Or the die-casting wheel made from a magnesium alloy as described in 5. The axle insertion portion has a first recess that opens in one of the two directions along the axial direction, and a second recess that opens in the other of the two directions. The magnesium alloy die-casting wheel according to any one of claims 1 to 6, wherein the die-casting wheel is formed so as to be arranged in at least one of the circumferential direction and the radial direction. The magnesium alloy die-casting wheel according to any one of claims 1 to 7, wherein the spoke portion is disposed at a central portion of the rim portion in the axial direction.

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