JPH06344044A - Manufacture of cam shaft - Google Patents

Abstract

PURPOSE:To provide the manufacture of a cam shaft by which a tubular shaft member and a cam piece with an axial hole are firmly joined. CONSTITUTION:While plural grooves are provided which extend on the inner circumferential surface of a cam piece in the axial direction, a plural number of bulge part to engaged with the grooves are provided on the outer circumferential surface of a shaft member, the cam piece is arranged on a supporting article with the shaft member inserted into the axial hole of the cam piece, and the shaft member is deformed in bulge in the radial direction to firmly join the cam piece with time shaft member. Desirably, the positioning of the cam piece is performed by arranging a positioning pin in a prescribed position around the circular hole of the supporting article; arranging the cam piece, which is provided with a pin storing hole capable of engaging with the positioning pin, in the supporting article so that the pin storing hole is fitted outside the positioning pin; and then inserting the shaft member into the axial hole and the circular hole.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a camshaft in which a tubular shaft member having a hollow portion and a cam piece having a shaft hole are joined together.

[0002]

2. Description of the Related Art Recently, in automobile engines, D
The number of camshafts tends to increase due to the adoption of the OHC mechanism, the V-shaped arrangement of cylinders, and the like, but there is a problem that the valve operating system of the engine becomes large and heavy. Therefore, a method of reducing the weight of the valve operating system by hollowing the camshaft has been proposed. For example, a tubular shaft member having a hollow portion is provided with a shaft hole having a diameter slightly larger than the outer diameter of the shaft member. After the fitted cam piece is externally fitted, the shaft member is bulged and deformed in the radial direction, the outer peripheral surface of the shaft member is pressed against the inner peripheral surface of the cam piece, and the shaft member and the cam piece are joined to form a camshaft. Proposed.

Specifically, after the cam piece is fitted onto the tubular shaft member, a high-pressure fluid is press-fitted into the hollow portion of the shaft member to bulge and deform the shaft member in the radial direction, thereby joining the shaft member and the cam piece. A method of manufacturing a camshaft (so-called bulge processing) has been proposed.
(For example, refer to Japanese Patent Publication No. 2-62333). In addition, after the cam piece is externally fitted to the tubular shaft member, the hollow portion of the shaft member is inserted with a steel ball or a diameter-expanding member having a diameter slightly larger than the hollow portion to bulge and deform the shaft member in the radial direction, A method of manufacturing a camshaft in which a shaft member and a cam piece are joined has been proposed (for example, see Japanese Utility Model Laid-Open No. 58-113805).

[0004]

However, such a conventional method for manufacturing a camshaft has a problem that the joining force between the shaft member and the cam piece is relatively weak and the durability of the camshaft is low. There is also a problem that positioning of the cam piece is difficult. The present invention has been made to solve the above conventional problems, and is a method for manufacturing a camshaft in which a cam piece having an axial hole and a tubular shaft member are joined by bulging deformation of the shaft member. It is an object of the present invention to provide a method for manufacturing a cam shaft, which can firmly join the cam piece and the shaft member and can easily position the cam piece.

[0005]

In order to achieve the above object, a first aspect of the present invention is to arrange a cam piece having a shaft hole at a predetermined position, and to form a tubular shaft member having a hollow portion into the shaft hole of the cam piece. In the manufacturing method of the camshaft, the shaft member is bulged and deformed in the radial direction to form the camshaft by joining the campiece and the shaft member. A plurality of groove portions extending in the axial direction of the shaft hole are provided at predetermined positions, while a bulge portion extending in the axial direction of the shaft member and capable of engaging with the groove portion is provided on the outer peripheral surface of the shaft member to support the cam piece. After arranging it in the prescribed part of
The shaft member is inserted into the axial hole of the cam piece so that the groove portion and the bulge portion are engaged with each other, and thereafter, in the hollow portion of the shaft member, a pipe expanding jig having a pipe expanding portion having a diameter larger than the hollow portion is provided. Provided is a method for manufacturing a cam shaft, characterized in that the cam piece and the shaft member are joined by press-fitting and bulging and deforming the shaft member in the radial direction.

A second aspect of the present invention is the method for manufacturing a camshaft according to the first aspect, in which a support tool having a circular hole having a diameter larger than a maximum radial length of the shaft member is prepared, A positioning pin is arranged at a predetermined position around the circular hole of the support tool, and a cam piece having a pin receiving hole that can engage with the positioning pin is attached to the support tool so that the pin receiving hole is fitted onto the positioning pin. There is provided a method for manufacturing a camshaft, characterized in that the cam piece is positioned by arranging the shaft member and then inserting the shaft member into the shaft hole and the circular hole.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS As a preferred embodiment of the present invention, a method for manufacturing a camshaft for intake valve of a DOHC type V6 engine (V6 engine) will be specifically described below with reference to the flow chart shown in FIG. As shown in FIG. 1, in step # 1, a support tool for supporting the cam shaft or parts thereof is assembled during manufacture of the cam shaft. Figure 2 (a),
As shown in (b), the support S includes one base plate 1 forming the bottom thereof, a plurality of upper plates 2 arranged at a predetermined interval above the base plate 1, and a space between the plates 1 and 2. And a plurality of cylindrical inter-plate members 3 that are arranged in the space to regulate the distance between the plates 1 and 2, and a plurality of connections that connect and fix the plates 1 and 2 and the plate-to-plate member 3 in their arrangement direction. It is composed of a rod 4 and. Here, the lower end of the connecting rod 4 is fixed to the base plate 1 using a connecting bolt 5. Further, a fastening bolt 7 is screwed into the upper end portion of the connecting rod 4 via a washer 6 arranged on the upper surface of the uppermost upper plate 2, and by a fastening force between the connecting rod 4 and the fastening bolt 7. The upper plates 2 and the cylindrical members 3 are fixed to each other. In addition,
As will be described later, each of the base plate 1 and each upper plate 2 is composed of two half plates, and the corresponding half plates have connecting pins 8 and fastening screws 9 respectively.
And are connected and integrated using.

Each member constituting the support S will be described below. As shown in FIGS. 3 (a) and 3 (b), the first half plate 1 a of the base plate 1 has an upper hole portion 11, an intermediate hole portion 12 having a smaller diameter than the upper hole portion 11, and an upper hole portion 11.
And lower holes 13 having the same diameter are provided in series with their axes oriented in the thickness direction of the first half plate 1a. Here, the upper hole 11 is opened on the upper surface of the first half plate 1a, the lower hole 13 is opened on the lower surface of the first half plate 1a, and the intermediate hole 12 is the upper hole 11 and the lower hole. 1
It communicates with 3. The first half plate 1a is provided with two sets of such a series of holes 11 to 13. Here, when the support tool S is assembled, the upper hole portion 11
The lower end of the connecting rod 4 is inserted into the connecting rod 4, and then the connecting bolt 5 is screwed into the screw hole 23 (see FIG. 8) of the connecting rod 4 from the lower hole portion 13 side through the intermediate hole portion 12. The plate 1a and the connecting rod 4 are fixed (see FIG. 2).

Further, the first half plate 1a has a connecting pin insertion hole 14a and a screw hole portion 15a whose axes are oriented in a direction orthogonal to the mating surface with the second half plate 1b (see FIG. 4). The connecting pin insertion hole 14a and the screw hole portion 15a are provided on the mating surfaces of the second half plate 1b. In addition, the first half plate 1a,
Two sets of connection pin insertion holes 14a and screw hole portions 15a are provided.

As shown in FIGS. 4 (a) and 4 (b), the second half plate 1b of the base plate 1 has an upper hole portion 11, an intermediate hole portion 12, and a lower hole portion as in the first half plate 1a. 13 and 13 are provided (only one set is provided). Further, the second half plate 1b has a connecting pin insertion hole 1 at a position corresponding to the connecting pin insertion hole 14a of the first half plate 1a.
4b is provided, and at a position corresponding to the screw hole portion 15a of the first half plate 1a, a hole portion 15b that penetrates the second half plate 1b in the plane direction is provided. Here, when assembling the support S, first, a half portion of the connecting pin 8 is inserted into the connecting pin insertion hole 14a, and then the connecting pin 8 is inserted.
The exposed portion (portion not inserted into the connecting pin insertion hole 14a) is inserted into the connecting pin insertion hole 14b, whereby the first half plate 1a and the second half plate 1b are positioned, and then the fastening screw 9 is , Second half plate 1
It is screwed into the screw hole 15a from the b side through the hole 15b,
The first half plate 1a and the second half plate 1b are connected and fixed (see FIG. 2).

As shown in FIGS. 5 (a) and 5 (b), the first half plate 2a of the upper plate 2 is provided with two holes 16 through which the connecting rod 4 is inserted. A semicircular cutout 17a is provided facing the mating surface with the second half plate 2b (see FIG. 6), and the cam piece 26 (see FIG. 10) is positioned in the vicinity of the cutout 17a. A pin hole 18 is provided for inserting a pin (not shown). Further, in the first half plate 2a, a connecting pin insertion hole 19a and a screw hole portion 2 whose axes are oriented in directions orthogonal to the mating surface with the second half plate 2b, respectively.
0a are provided. These connecting pin insertion holes 19a
The screw hole portion 20a and the screw hole portion 20a are opened on the mating surface with the second half plate 2b. The first half plate 2
Two sets of connection pin insertion holes 19a and screw hole portions 20a are provided in a.

As shown in FIGS. 6 (a) and 6 (b), the second half plate 2b of the upper plate 2 also has a hole 16 (only one) and a notch, as in the first half plate 2a. A portion 17b and a pin hole 18 (however, two holes) are provided. In addition, the connecting pin insertion hole 1 of the first half plate 2a
A connecting pin insertion hole 19b is provided at a position corresponding to 9a,
A hole 20b is provided at a position corresponding to the screw hole 20a of the first half plate 2a and extends through the second half plate 2b in the plane direction. The method of assembling the first half plate 2a and the second half plate 2b when assembling the support S is the same as that of the base plate 1.

When the upper plate 2 is assembled, a circular hole 17 is formed near the center of the upper plate 2 by the notches 17a and 17b, and three pin holes 18 are located around the circular hole 17. The circular hole 17 has a diameter slightly larger than the maximum radial length of the shaft member 25 (see FIG. 10) described later, so that the shaft member 25 can pass through the circular hole 17. . In this embodiment, the engine is a V6 type, so three pin holes 1
Reference numerals 8 are arranged at positions separated by 120 ° in the center angle in the circumferential direction of the circular hole 17. The number of such pin holes and the positions to be arranged differ depending on the engine type. For example, in the case of a camshaft of a four-cylinder engine, four pin holes are provided, and these pin holes have a central angle in the circumferential direction. 90 °
They will be placed at separate positions.

As shown in FIGS. 7 (a) and 7 (b), a cylindrical inter-plate member 3 having a through hole 22 through which the connecting rod 4 is inserted.
In order to regulate the distance between the base plate 1 and the lowermost upper plate 2 or the distance between the upper plates 2, that is, in the axial direction of the shaft of the cam piece 26 (see FIG. 10) or the journal 33 (see FIG. 10). It is provided to regulate the arrangement position. Therefore, the axial length of each inter-plate member 3 varies depending on which plate is arranged. As shown in FIG. 8, screw holes 23 for screwing the connecting bolts 5 or the fastening bolts 7 are provided at both ends of the connecting rod 4.
(See Figure 2).

For assembling the support S, for example, the base plate 1 and the upper plate 2 are first assembled by connecting the corresponding half plates using the connecting pin 8 and the fastening screw 9, and then the connecting bolt 5 is attached. The connecting rod 4 is attached to the base plate 1 by using it, and then the inter-plate member 3 and the upper plate 2 are stacked on the base plate 1 in a predetermined order, and the fastening bolt 7 is attached to the upper end portion of the connecting rod 4 via the washer 6. The procedure is such as screwing into the screw hole 23.

At step # 2, a cam piece or a journal is arranged at a predetermined position on the upper surface of each upper plate 2. Specifically, the support S has an upper plate 2
10 pieces are arranged, and from the upper side to the lower side, 1,
The journals are arranged on the 4th, 7th and 10th upper plates 2, and the cam pieces are arranged on the 2nd, 3rd, 5th, 6th, 8th and 9th upper plates 2.

As shown in FIG. 9 (a), the cam piece 26 is made of an iron material (for example, steel) having predetermined physical properties, and a positioning pin (not shown) is provided at the center of the cam nose portion 27. Is provided with a pin accommodating hole 28.
Further, the cam piece 26 is provided with a substantially cylindrical shaft hole 29 penetrating the cam piece 26 in the thickness direction, and basically, the shaft hole 29 can be just inserted with the shaft member 25 shown in FIG. 9B. It is dimensioned to be possible. Further, on the inner peripheral surface of the cam piece 26, that is, the inner peripheral surface of the shaft hole, six groove portions 30 extending in the shaft hole axial direction (cam piece thickness direction) are formed. Of these groove portions 30, one is the shaft hole 2
The cam nose portion 27 is arranged at a position (near the pin accommodating hole 28) corresponding to the most bulged portion of the cam nose portion 27 when viewed in the circumferential direction. The six groove portions 30 are arranged at positions separated by 60 ° from each other at the central angle in the circumferential direction of the shaft hole 29. Here, the cross-sectional shape of each groove 30 is substantially arcuate, and the depth thereof is set to about 0.3 mm. The number of the groove portions 30 and the positions to be arranged are not limited to those described above, and can be variously set.

When the cam piece 26 is arranged on the upper surface of the upper plate 2, a positioning pin (not shown) is provided in a predetermined one of the three pin holes 18 of the upper plate 2 before the cam piece 26 is arranged. ) Is inserted. In this embodiment, in the second and third upper plates 2 from the upper side to the lower side, the pin holes arranged at the same position (for convenience, referred to as the first pin insertion position) when viewed in the circumferential direction of the circular hole 17. A positioning pin is inserted in 18 and the 5th and 6th upper plates 2 have a circular hole 1 with respect to the first pin insertion position.
Pin holes 18 arranged at positions separated by 120 ° in the circumferential direction of 7 (for convenience, this is referred to as a second pin insertion position)
A positioning pin is inserted into the pin hole 18 of the 8th and 9th upper plates 2 which is 120 ° apart from the second pin insertion position in the circumferential direction of the circular hole 17 by the central angle. The positioning pin is inserted. Then, the cam piece 26 is arranged on the corresponding upper plate 2 such that the pin accommodating hole 28 is fitted onto the positioning pin and the shaft hole 29 substantially overlaps with the circular hole 17 in a plan view. .

As shown in FIG. 9 (c), the journal 33 is made of the same iron-based material as the cam piece 26, and the journal 33 is provided with a substantially cylindrical shaft hole 34 penetrating the journal 33 in the thickness direction. ing. The shaft hole 34 has the same shape as the shaft hole 29 of the cam piece 26, and six groove portions 35 extending in the shaft hole axial direction (journal thickness direction) are formed on the inner peripheral surface thereof. Needless to say, the shape or the arrangement position of these groove portions 35 is the same as the groove portion 30 of the cam piece 26. Since the journal 33 has no directivity unlike the cam piece 26, the journal 33 is arranged on the corresponding upper plate 2 without using a positioning pin so that the shaft hole 34 substantially overlaps the circular hole 17 in plan view. .
FIGS. 2A and 2B show a state in which the cam pieces 26 and the journals 33 are thus arranged on the corresponding upper plates 2, respectively.

In step # 3, the cam pieces 26 arranged at the predetermined positions on the corresponding upper plate 2 are arranged.
A tubular shaft member 25 having a hollow portion 24 as shown in FIG. 9B or 10 in the shaft hole 29 and shaft hole 34 of the journal 33 and the circular hole 17 of the upper plate 2.
Is inserted. As shown in FIGS. 9B and 10, the outer peripheral surface of the shaft member 25 is formed with six bulge portions 32 extending in the axial direction of the shaft member. These bulges 32 are arranged at positions separated from each other by 60 ° at the central angle in the circumferential direction of the shaft member. here,
The lateral cross-sectional shape of each bulge portion 32 is a substantially arcuate shape that can be engaged with the groove portions 30, 35, and the height thereof is the groove portions 30,
It is set to about 0.2 mm, which is slightly smaller than the depth of 35.

As described above, since each cam piece 26 is positioned by the positioning pin, when the shaft member 25 is fitted into the shaft hole 29 and the shaft hole 34 and the circular hole 17, each cam piece 26 naturally moves. It is accurately arranged at a predetermined position in the circumferential direction. Therefore, the positioning of the cam piece 26 becomes very easy, and the accuracy of the arrangement is improved. The cam piece 26 has a pin receiving hole 28.
Is formed, the weight is lightened accordingly, and the camshaft C is lightened.

In step # 4, the pipe expanding jig is press-fitted into the hollow portion 24 of the shaft member 25, and the shaft member 25 is bulged (plastically deformed) outward in the radial direction. As shown in FIG. 11, the tube expanding jig J substantially has a substantially cylindrical shaft portion 36 and a slightly larger diameter than the shaft portion 36 (for example,
Spherical expansion section 37 having a diameter of 0.5 to 1.0 mm larger)
It consists of and. Here, the diameter of the pipe expanding portion 37 is set to be slightly larger than the inner diameter of the hollow portion 24 of the shaft member 25, and when the pipe expanding jig J is press-fitted into the hollow portion 24, the shaft member 25 is radially expanded by the pipe expanding portion 37. It can be bulged and deformed outward. The expanded portion 37 is made of an iron-based material (for example, S55C) having a predetermined hardness (for example, HRC50 or higher). In addition,
The expanded tube portion 37 is not limited to a spherical shape, but may have any shape as long as the shaft member 25 can be bulged and deformed substantially uniformly in the radial direction (for example, a cylinder). Shape, egg shape, etc.).

Then, the pipe expanding jig J is press-fitted into the hollow portion 24 of the shaft member 25 with a predetermined pressing force (for example, 3 to 4.5 tons) by using a press device (not shown) or the like. As a result, the shaft member 25 is bulged and deformed outward in the radial direction by the pipe expanding jig J (the pipe expanding portion 37), as shown in FIG.
As shown in (b), the outer peripheral surface of the shaft member 25 is brought into pressure contact with the inner peripheral surface of the cam piece 26 and the inner peripheral surface of the journal 33, so that the shaft member 25 and each cam piece 26 and each journal 33 are firmly joined. To be made. At this time,
The bulge portion 32 of the shaft member 25 is the cam piece 26.
Since it fits into the groove portion 30 of the camshaft and the groove portion 35 of the journal 33, the joining force between the shaft member 25 and the cam piece 26 and the journal 33 is sufficiently increased, and the camshaft
The durability (see FIG. 13) is significantly improved.

In step # 5, the tube expanding jig J is removed from the hollow portion 24 of the shaft member 25. Then, in step # 6, the support S is partially disassembled and the camshaft C is taken out. In this case, the fastening screws 9 that fasten the half plates 1a and 1b of the base plate 1 and the half plates 2a and 2b of the upper plates 2 are fastened.
By simply removing the fastening screw 9 that fastens, the support tool S is vertically divided into two, and the camshaft C can be removed.

In step # 7, the camshaft C is subjected to predetermined post-processing. That is, as shown in FIG. 13, the end plate 38, the bearing portion 39, the sprocket attachment portion 40, and the like are attached to the camshaft C,
The camshaft C is completed. The sprocket mounting portion 40 is fixed to the camshaft main body using a fixing pin 41.

In this way, the five camshafts C (No. 1 to N) actually manufactured by the manufacturing method according to the present invention are manufactured.
The results of measuring the strength and durability in the circumferential direction of o.5) are shown below. The strength of the camshaft C in the circumferential direction is determined by fixing the shaft member 25 and then applying a force in the circumferential direction of the camshaft, that is, torque, to the cam piece 26.
This torque is gradually increased, and the torque value (kg-m) at the time when the cam piece 26 starts to shift in the circumferential direction with respect to the shaft member 25 is shown. The shape and material of each member of these camshafts C are as follows. Cam piece thickness ； 14mm Cam piece material ； S50C Number of cam piece groove ； 12 Shaft member outer diameter ； 32.4mm Shaft member inner diameter ； 24mm Shaft material ； STKM17C-SC Number of shaft member bulge ； 12 Expansion pipe Outside diameter of expanded part of jig: 24.8 mm

<Chamshaft circumferential strength> No. 1 112 kg-m No. 2 88 kg-m No. 3 100 kg-m No. 4 110 kg-m No. 5 95 kg-m (average) (101 kg-m) As described above, all of the five camshafts C have sufficient circumferential strength.

Further, these camshafts C (No. 1 to No. 1)
No. 5), the results of measuring the strength or durability in the axial direction of the camshaft are shown below. The strength of the cam shaft C in the cam shaft axial direction is determined by the shaft member 25.
Then, a force in the axial direction of the camshaft is applied to the cam piece 26, the force is gradually increased, and the pressing force at the time when the cam piece 26 starts to shift relative to the shaft member 25 in the axial direction of the camshaft axial line ( ton). <Camshaft axial strength> No. 1 3.1 ton No. 2 3.5 ton No. 3 4.3 ton No. 4 4.0 ton No. 5 3.5 ton (average) (3. 7 ton) As described above, each of the camshafts C has sufficient strength in the axial direction.

As described above, according to the manufacturing method of the present invention, the shaft member 25, the cam piece 26, and the journal 33 can be firmly joined to each other, and the durability of the camshaft C is significantly improved. Also, the cam piece 2
The positioning of 6 is extremely easy.

[0030]

According to the first aspect of the present invention, the outer peripheral surface of the shaft member is brought into pressure contact with the inner peripheral surface of the cam piece by press fitting of the pipe expanding jig, so that the shaft member and the cam piece are joined. At this time, since the bulge portion of the shaft member fits into the groove portion of the cam piece, the joining force between the shaft member and the cam piece is sufficiently increased, and the durability of the cam shaft is significantly improved.

According to the second invention, basically, the same operation and effect as those of the first invention can be obtained. Further, when the cam piece is arranged, the cam piece is positioned by the pin accommodating hole and the positioning pin. Therefore, when the shaft member is inserted into the shaft hole and the circular hole, the cam piece is naturally arranged at a predetermined position accurately. Therefore, the cam piece can be arranged or positioned very easily, and the dimensional accuracy of the cam shaft can be improved. Further, the weight of the camshaft is reduced by the amount of the pin receiving hole formed.

[Brief description of drawings]

FIG. 1 is a flowchart showing a method for manufacturing a camshaft.

2 (a) and 2 (b) are a plan explanatory view and an elevational explanatory view of a support tool, respectively.

3A and 3B are a plan explanatory view and an elevational explanatory view of a first half plate constituting a base plate, respectively.

4 (a) and 4 (b) are an elevational view and a plan view, respectively, of a second half plate constituting the base plate.

5 (a) and 5 (b) are a plan explanatory view and an elevational explanatory view of a first half plate constituting an upper plate, respectively.

6 (a) and 6 (b) are an elevational view and a plan view, respectively, of a second half plate constituting the upper plate.

7A and 7B are a side view and a view of an axial direction of an inter-plate member, respectively.

FIG. 8 is a side view of the connecting member.

9 (a) is a view of the cam piece as viewed from the axial direction, and FIG. 9 (b) is a view of the shaft member as viewed from the axial direction,
(c) is a view of the journal as viewed from the axial direction.

FIG. 10 is a perspective explanatory view of a shaft member with a cam piece and a journal.

FIG. 11 is a schematic view of the vicinity of the tip of the tube expanding jig.

FIG. 12A is a diagram showing a joint state between a shaft member and a cam piece, and FIG. 12B is a diagram showing a joint state between a shaft member and a journal.

FIG. 13 is a side view illustrating a completed camshaft.

[Explanation of symbols]

 C ... Cam shaft J ... Expanding jig S ... Supporting tool 17 ... Circular hole 24 ... Hollow part 25 ... Shaft member 26 ... Cam piece 28 ... Pin accommodating hole 29 ... Axial hole 30 ... Groove 32 ... Bulging part 37 ... Expanding part

Claims (2)

[Claims] 1. A cam piece provided with an axial hole is arranged at a predetermined position, a tubular shaft member having a hollow portion is fitted into the axial hole of the cam piece, and then the shaft member is bulged and deformed in a radial direction, A method for manufacturing a camshaft, wherein a campiece and a shaft member are joined together to form a camshaft, wherein a plurality of grooves extending in the axial direction of the axial hole are provided at predetermined positions on the inner peripheral surface of the axial hole of the campiece. , The outer peripheral surface of the shaft member is provided with a bulge portion extending in the axial direction of the shaft member and having a shape capable of engaging with the groove portion, the cam piece is arranged at a predetermined portion of the support, and then the groove portion and the bulge portion are provided. The shaft member is fitted into the shaft hole of the cam piece so that the two members engage with each other, and then a pipe expanding jig having a pipe expanding portion having a diameter larger than the hollow portion is press-fitted into the hollow portion of the shaft member to A method of manufacturing a camshaft, characterized in that the cam member and the shaft member are joined together by bulging and deforming the cam member in the radial direction. 2. The method of manufacturing a camshaft according to claim 1, wherein a support tool having a circular hole having a diameter larger than a maximum radial length of the shaft member is prepared, and the circumference of the circular hole of the support tool is provided. Locating the positioning pin at a predetermined position of, and arranging the cam piece having the pin accommodating hole engageable with the locating pin on the support tool so that the pin accommodating hole is fitted over the locating pin, A method for manufacturing a camshaft, characterized in that the cam piece is positioned by inserting a member into the shaft hole and the circular hole.