Camshaft-manufacturing method and gear shaft-manufacturing method

1. A camshaft-manufacturing method, comprising:

preparing a plurality of split dies including recessed cam accommodation portions provided on side surfaces and rib accommodation portions formed in the recessed cam accommodation portions, configuring a split die group by butting side surfaces of the split dies, and forming a plurality of cam accommodation portions including the recessed cam accommodation portions between each adjacent pair of the split dies, in order to prepare the split die group;

preparing a cam including a through-hole, a cam body which is smaller than each of the cam accommodation portions, and ribs which are provided on both sides in a thickness direction of the cam body and configured to be fitted into the rib accommodation portions, and a hollow shaft, and arranging the cam and the shaft so that the cam body is accommodated in the cam accommodation portions, the ribs are fitted in the rib accommodation portions, and the hollow shaft is inserted into the through-hole of the cam, in order to prepare processing; and

introducing pressurized fluid into a hollow portion of the hollow shaft and performing hydroform processing, and fixing the cam to the hollow shaft by expanding the hollow shaft, in order to perform the processing.

2. The camshaft-manufacturing method according to claim 1 , further comprising:

preparing a pair of the split die groups in preparing the split die group; and

fixing the cam and the hollow shaft so as to be interposed by the pair of split die groups in preparing processing.

3. The camshaft-manufacturing method according to claim 2 ,

wherein a plurality of rib-receiving surfaces are provided on the rib accommodation portions of the plurality of split dies, a plurality of abutting surfaces are provided on the ribs of the cam, the abutting surfaces abut the rib-receiving surfaces when the cam is disposed on the cam accommodation portions, and the cam is fixed to the cam accommodation portions.

4. The camshaft-manufacturing method according to claim 3 ,

wherein the plurality of rib-receiving surfaces of the plurality of split dies are configured of horizontal surfaces and a pair of vertical surfaces, and the plurality of abutting surfaces of the ribs of the cam are configured of first abutting surfaces abutting the horizontal surfaces and second abutting surfaces abutting the vertical surfaces.

5. The camshaft-manufacturing method according to claim 3 ,

wherein the plurality of rib-receiving surfaces of the plurality of split dies are configured of inclined surfaces, and the plurality of abutting surfaces of the ribs of the cam are configured of at least two of the plurality of abutting surfaces abutting the inclined surfaces.

6. The camshaft-manufacturing method according to claim 3 ,

wherein in the pair of split die groups, the plurality of rib-receiving surfaces of the plurality of split dies configuring a first split die group configured of inclined surfaces,

wherein the plurality of rib-receiving surfaces of the plurality of split dies configuring a second split die group configured of horizontal surfaces, and

wherein the plurality of abutting surfaces of the ribs are configured of at least two of the plurality of abutting surfaces abutting the inclined surfaces, and at least another two of the plurality of abutting surfaces abutting the horizontal surfaces.

7. The camshaft-manufacturing method according to claim 1 ,

wherein a plurality of rib-receiving surfaces are provided on the rib accommodation portions of the plurality of split dies, a plurality of abutting surfaces are provided on the ribs of the cam, the abutting surfaces abut the rib-receiving surfaces when the cam is disposed on the cam accommodation portions, and the cam is fixed to the cam accommodation portions.

8. The camshaft-manufacturing method according to claim 7 ,

wherein the plurality of rib-receiving surfaces of the plurality of split dies are configured of horizontal surfaces and a pair of vertical surfaces, and the plurality of abutting surfaces of the ribs are configured of first abutting surfaces abutting the horizontal surfaces and second abutting surfaces abutting the vertical surfaces.

9. The camshaft-manufacturing method according to claim 7 ,

wherein the plurality of rib-receiving surfaces of the plurality of split dies are configured of inclined surfaces, and the plurality of abutting surfaces of the ribs are configured of at least two of the plurality of abutting surfaces abutting the inclined surfaces.

10. The camshaft-manufacturing method according to claim 7 ,

wherein in a pair of split die groups, the plurality of rib-receiving surfaces of the plurality of split dies configuring a first split die group configured of inclined surfaces,

wherein the plurality of rib-receiving surfaces of the plurality of split dies configuring a second split die group configured of horizontal surfaces, and

wherein the plurality of abutting surfaces of the ribs of the cam configured of at least two of the plurality of abutting surfaces abutting the inclined surfaces, and at least another two of the plurality of abutting surfaces abutting the horizontal surfaces.

11. The camshaft-manufacturing method according to claim 1 ,

wherein in the preparing the cam, after the cam is mounted on the split die group so that the cam body is accommodated in the cam accommodation portion and the ribs are fitted into the rib accommodation portions, the hollow shaft is inserted into the through-hole of the cam.

12. The camshaft-manufacturing method according to claim 1 ,

wherein in the preparing the cam, after the hollow shaft is inserted into the through-hole of the cam, the cam is mounted on the split die group so that the cam body is accommodated in the cam accommodation portion and the ribs are fitted into the rib accommodation portions.

13. A gear shaft-manufacturing method, comprising:

preparing a plurality of split dies including recessed gear accommodation portions provided on side surfaces and rib accommodation portions formed in the recessed gear accommodation portions, configuring a split die group by butting side surfaces of the split dies, and forming a plurality of gear accommodation portions including the recessed gear accommodation portions between each adjacent pair of the split dies, in order to prepare the split die group;

preparing a gear including a through-hole, a gear body which is smaller than each of the gear accommodation portions, and ribs which are provided on both sides in a thickness direction of the gear body and configured to be fitted into the rib accommodation portions, and a hollow shaft, and arranging the gear and the hollow shaft so that the gear body is accommodated in the gear accommodation portions, the ribs are fitted in the rib accommodation portions, and the hollow shaft is inserted into the through hole of the gear, in order to prepare processing; and

introducing pressurized fluid into a hollow portion of the hollow shaft and performing hydroform processing, and fixing the gear to the hollow shaft by expanding the hollow shaft, in order to perform the processing.