JPH11336512A - Manufacture of hollow cam shafts and manufacturing device therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress temperature rise of a shaft part and prevent it from softening with heat by supplying a cooling liquid into a hollow cam shaft when an anti-abrasive material is cladded on a part to be processed. SOLUTION: This hollow cam shaft A furnished with a cam part C consolidatedly is formed in a shaft part S through a plastic processing of a steel pipe, and an anti-abrasive material M is cladded on a part to be processed B of the cam part C, when a cooling liquid is supplied into the hollow cam shaft A, and at the same time, cladding of the material M is performed. Thereby temp. rise in the cladding part and its surrounding area is suppressed, and a sufficient hardness is obtained in the cladding layer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for manufacturing a hollow camshaft for an engine in which a cam portion is integrally formed on a shaft portion. The present invention relates to a method and an apparatus for manufacturing a hollow camshaft used in such a case.

[0002]

2. Description of the Related Art This kind of hollow camshaft is intended to reduce the weight of a hollow camshaft manufactured by casting or forging, and is manufactured by using a pipe-shaped shaft and a wear-resistant material. A cam piece and a journal piece are used. Each piece is manufactured by burning or forging / carburizing. The pieces are fixed to the shaft by assembling the pieces on the shaft, disposing them in a mold, and expanding the shaft with the pressure of the liquid supplied to the inside of the shaft.

[0003]

However, in the production of the above-mentioned conventional hollow camshafts, the number of man-hours is increased due to the production, assembly, setting in a mold, pipe expansion by hydraulic pressure, and the like. As a result, productivity is low, and since only the shaft is hollowed out, there is a limit in weight reduction.

Therefore, in recent years, a steel pipe is plastically worked to form a cam integrally with a shaft, and the whole is hollowed.
Thereafter, a manufacturing method has been proposed in which a wear-resistant material is built up from the ramp portion of the cam, which particularly requires wear resistance, to the nose top portion. In this case, the abrasion-resistant material to be built up on the cam needs to have a thickness of at least 2 mm including a machining allowance for a grinding process performed later.

However, in the production of the above-mentioned hollow camshaft, when building up a wear-resistant material on the cam,
The heat causes a problem that the shaft is softened, and the temperature of the shaft increases, which slows down the solidification rate of the abrasion-resistant material. There is a problem that abrasion cannot be obtained, and solving such a problem has been a problem.

[0006]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned conventional problems. In a hollow camshaft having a cam portion integrally formed on a shaft portion, the present invention relates to a method for depositing a wear-resistant material on a cam portion. It is an object of the present invention to provide a method and an apparatus for manufacturing a hollow camshaft which can suppress a rise in the temperature of a shaft portion and obtain sufficient wear resistance of a build-up layer.

[0007]

According to a first aspect of the present invention, there is provided a method of manufacturing a hollow camshaft, comprising forming a hollow camshaft integrally formed with a cam portion in a shaft portion by plastically processing a steel pipe. When abrasion-resistant material is built up on the processed part from the ramp part to the nose top part, a cooling liquid is supplied inside the hollow cam shaft and the abrasion-resistant material is built up. , As claim 2,
A laser is used as a means for depositing the wear-resistant material, wherein the cooling liquid supplied to the inside of the hollow cam shaft is 10 m from the laser irradiation position.
In this case, the cladding is formed while cooling to a temperature of 5 to 140 [deg.] C. at a distance of m, and as a wear-resistant material, a carbon content of 1 to 4% by weight is selected from steel or cast iron material. In a fifth aspect, a powder material is used, and as a fifth aspect, the hollow camshaft is configured to be built while rotating around the axis at a speed of 0.4 to 1.4 m / min. A construction is performed in which the cooling liquid is supplied to the inside of the hollow camshaft at a flow rate of 10 to 40 l / min. And the above configuration is used as means for solving the problem.

As the cooling liquid in the first aspect, water or an appropriate refrigerant solution can be used.
As the laser in the above, Nd: YAG laser, CO ₂
A laser, a semiconductor laser, or the like can be used. In Claim 3, the temperature at a position 10 mm away from the laser irradiation position is set to 5 to 140 ° C. If the temperature is set to less than 5 ° C., poor welding of the wear-resistant material to the workpiece may occur. If the temperature is higher than 140 ° C., the solidification rate of the wear-resistant material is reduced, and the hardness of the build-up layer may be reduced. Further, according to claim 5, the rotation speed of the hollow camshaft about the axis is 0.4 to 1.4 m.
/ Min is 0.4 m / m when the position where the build-up is performed on the rotating hollow camshaft is fixed.
If the thickness is smaller than "in", the thickness of the cladding layer may be more than necessary. If the thickness is larger than 1.4 m / min, a sufficient thickness of the cladding layer may not be obtained. Furthermore, in claim 6, the flow rate of the cooling liquid is set to 10 to 40 l / min. When the flow rate is smaller than 10 l / min, a sufficient cooling effect cannot be obtained.
If it is larger than 40 l / min, the cooling effect does not change so much, but the burden on the circulation system of the cooling liquid increases.

According to a eighth aspect of the present invention, there is provided a hollow camshaft manufacturing apparatus according to claim 8, wherein a nose is formed from a ramp portion of a cam portion to a hollow camshaft in which a shaft portion and a cam portion are integrally formed by plastically processing a steel pipe. A device for overlaying a wear-resistant material on a workpiece to be processed to a top portion, wherein a heating means for welding the wear-resistant material to the workpiece and a cooling liquid supplied to the inside of the hollow camshaft. The liquid supply means is provided, and as a ninth aspect, a closing means for closing one end of the hollow camshaft is provided, and the liquid supply means is inserted into the hollow camshaft from the other end thereof and is provided with the closing means. A liquid supply pipe having an ejection hole in the vicinity is provided, and a discharge portion for cooling liquid is provided on the other end side of the hollow camshaft. A second liquid supply pipe having an injection hole facing the inner surface of the portion to be processed in the liquid supply means, wherein the second liquid supply pipe of the liquid supply means is a hollow cam together with the heating means. According to a twelfth aspect, the outer diameter of the liquid supply pipe of the liquid supply means is 1/5 to 1/3 of the inner diameter of the hollow camshaft. The configuration is a means for solving the problem.

In the twelfth aspect, the outer diameter of the liquid supply pipe is set to １ ／ to ３ of the inner diameter of the hollow camshaft.
If it is smaller than 1/5, it takes time to fill the inside of the hollow camshaft with the cooling liquid, and the smooth supply and discharge of the cooling liquid may be impaired.
If it is larger than / 3, contact between the hollow camshaft and the liquid supply pipe is likely to occur, which may make it difficult to move the liquid supply pipe smoothly, and may increase the smoothness of supply and discharge of the cooling liquid. This is because it may be damaged.

[0011]

According to the method of manufacturing a hollow camshaft according to the first aspect of the present invention, a hollow camshaft having a cam portion integrally formed on a shaft portion is formed by plastically processing a steel pipe, and the hollow camshaft is formed from a ramp portion of the cam portion. By supplying a cooling liquid inside the hollow camshaft when overlaying the wear-resistant material on the work part reaching the nose top part, the temperature rise around the work part is suppressed, and the shaft by heat In addition to preventing the softening of the part, the solidification rate of the wear-resistant material is prevented from being reduced.

In the method for manufacturing a hollow camshaft according to the second aspect of the present invention, a laser is used as a means for overlaying a wear-resistant material, so that overlaying with high positioning accuracy can be performed. , Can prevent excessive heat input.

In the method of manufacturing a hollow camshaft according to the third aspect of the present invention, the position which is 10 mm away from the laser irradiation position is overlaid while being cooled to a temperature of 5 to 140 ° C., so that the resistance to the processed portion is reduced. Poor welding of the wear-resistant material and a decrease in the solidification rate of the wear-resistant material are prevented.

In the method for manufacturing a hollow camshaft according to claim 4 of the present invention, the carbon content of the wear-resistant material is 1%.
The processed portion of the hollow camshaft is overlaid with a powder material selected from steel or cast iron material of up to 4% by weight.

In the method for manufacturing a hollow camshaft according to the fifth aspect of the present invention, the hollow camshaft may be formed in a range of 0.4 to 1.4.
By performing the build-up while rotating around the axis at a speed of m / min, the build-up is performed from a fixed position on the rotating hollow camshaft, and the thickness of the build-up layer becomes more than necessary. Or shortage is prevented.

In the method for manufacturing a hollow camshaft according to the sixth aspect of the present invention, the cooling effect is achieved by building up while supplying a cooling liquid at a flow rate of 10 to 40 l / min into the hollow camshaft. Insufficiency and an increase in the burden on the circulation system of the cooling liquid are prevented.

In the method for manufacturing a hollow camshaft according to a seventh aspect of the present invention, the portion to be processed is concentrated by spraying a cooling liquid onto the inner surface of the portion to be processed in the hollow camshaft. And the cooling effect is enhanced.

In the manufacturing apparatus for a hollow camshaft according to the eighth aspect of the present invention, the hollow camshaft in which the shaft portion and the cam portion are integrally formed by plastically processing a steel pipe is used to form a nose top from the ramp portion of the cam portion. In a device for overlaying a wear-resistant material on a workpiece to be processed to a part, when the wear-resistant material is welded to the workpiece of the hollow camshaft using a heating means, the inside of the hollow camshaft is supplied by a liquid supply means. By supplying the cooling liquid to the cooling member, a rise in the temperature around the processed portion is suppressed, the softening of the shaft portion due to heat is prevented, and the solidification speed of the wear-resistant material is prevented from being reduced.

In the apparatus for manufacturing a hollow camshaft according to the ninth aspect of the present invention, one end of the hollow camshaft is closed by the closing means, and a liquid supply pipe is inserted into the hollow camshaft from the other end. The cooling liquid is supplied from the injection hole of the liquid supply pipe near the closing means.
As a result, the cooling liquid flows from one end to the other end of the hollow camshaft, and cools the hollow camshaft that has been overlaid. The cooling liquid is discharged from a discharge portion at the other end of the hollow camshaft.

In the apparatus for manufacturing a hollow camshaft according to a tenth aspect of the present invention, in the liquid supply means, the cooling liquid is injected from the injection hole of the second liquid supply pipe to the inner surface of the processed portion of the hollow camshaft. Thereby, the processing portion is intensively cooled to enhance the cooling effect.

In the apparatus for manufacturing a hollow camshaft according to the eleventh aspect of the present invention, the second liquid supply pipe of the liquid supply means moves in the axial direction of the hollow camshaft together with the heating means. When the heating means is successively moved with respect to a plurality of cam parts arranged at a predetermined interval in the axial direction of the hollow camshaft and the build-up is performed, the second liquid supply The tube also moves at the same time and always corresponds to the inner surface of the portion to be processed.

In the apparatus for manufacturing a hollow camshaft according to the twelfth aspect of the present invention, the outer diameter of the liquid supply pipe of the liquid supply means is set to 1/5 to 1/3 of the inner diameter of the hollow camshaft. It takes time to fill the inside of the cooling liquid with the cooling liquid, prevents the liquid supply pipe from moving smoothly, and supplies the cooling liquid to the hollow camshaft and the hollow camshaft. The cooling liquid is smoothly discharged from the cooling device.

[0023]

According to the method for manufacturing a hollow camshaft according to the first aspect of the present invention, a hollow camshaft having a cam portion integrally formed on a shaft portion is moved from a ramp portion of the cam portion to a nose top portion. By supplying a cooling liquid to the inside of the hollow camshaft when overlaying the wear-resistant material on the workpiece to be processed, a rise in the temperature of the shaft is suppressed, and the shaft is not softened by heat. It is possible to prevent the solidification rate of the overlaid abrasion-resistant material from slowing down, to obtain a sufficient hardness of the overlaid layer, to be lightweight and to have excellent abrasion resistance. A hollow camshaft can be obtained.

According to the method for manufacturing a hollow camshaft according to the second aspect of the present invention, the same effect as that of the first aspect can be obtained, and a laser is used as a means for building up the wear-resistant material. Therefore, it is possible to perform overlaying with high positioning accuracy, reliably prevent the cam portion from being melted due to excessive heat input, and to improve the quality and productivity.

According to the method of manufacturing a hollow camshaft according to claim 3 of the present invention, the same effect as in claim 2 can be obtained, and a position 10 mm away from the laser irradiation position is set at 5 to 140 ° C. By performing the overlay while cooling to a temperature, it is possible to prevent poor welding of the wear-resistant material to the processed part and to prevent a decrease in the solidification rate of the wear-resistant material. Further improvements can be realized. Further, it is possible to use water or a coolant solution as the cooling liquid. In this case, since it is not necessary to cool the water or the coolant solution in advance by a cooling device such as a chiller, the cooling liquid circulation system The configuration can be simplified, which can contribute to reduction of equipment costs and simplification of maintenance.

According to the method of manufacturing a hollow camshaft according to claim 4 of the present invention, the same effect as in claims 1 to 3 can be obtained, and the carbon content of the wear-resistant material is 1 to 4 Since the powder material selected from the steel or the cast iron material is used in a weight%, a build-up layer having a sufficient abrasion-resistant structure and hardness as a cam sliding portion can be formed.

According to the method of manufacturing a hollow camshaft according to the fifth aspect of the present invention, the same effects as those of the first to fourth aspects can be obtained.
Since the build-up is performed while rotating around the axis at a speed of 1.4 m / min, the build-up is performed from a fixed position on the rotating hollow camshaft, and the workpiece is opposed to gravity. Abrasion-resistant material can be supplied without any trouble, and the build-up layer thickness is reliably prevented from becoming more or less than necessary, ensuring stable build-up layer thickness and quality. Can be obtained.

According to the method for manufacturing a hollow camshaft according to the sixth aspect of the present invention, the same effects as those of the first to fifth aspects can be obtained. Since the cladding is performed while supplying at a flow rate of 40 l / min, the cooling effect is not insufficient, and the burden on the circulation system of the cooling liquid is not increased, and the cooling liquid is supplied inside the hollow cam shaft. Circulation can be performed smoothly, and the cooling effect can be further enhanced.

According to the method for manufacturing a hollow camshaft according to the seventh aspect of the present invention, the same effects as those of the first to sixth aspects can be obtained, and the inner surface of the processed portion of the hollow camshaft is cooled. Since the build-up is performed while spraying the working liquid, the processed part is intensively cooled,
The cooling effect can be further enhanced.

According to the hollow camshaft manufacturing apparatus according to the eighth aspect of the present invention, the hollow camshaft in which the shaft portion and the cam portion are integrally formed by plastic working of the steel pipe is provided from the ramp portion of the cam portion. In a device for overlaying a wear-resistant material on a portion to be processed reaching a nose top portion, when the wear-resistant material is welded to the portion to be processed of the hollow camshaft using a heating means, the hollow camshaft is supplied by a liquid supply means. Since the cooling liquid is supplied to the inside of the shaft, a rise in the temperature of the shaft portion is suppressed, and the softening of the shaft portion due to heat can be prevented, and the solidification rate of the overlaid abrasion-resistant material is reduced. It is possible to reliably prevent the delay, to obtain a sufficient hardness of the build-up layer, and to obtain a hollow camshaft that is lightweight and has excellent wear resistance.

According to the apparatus for manufacturing a hollow camshaft according to the ninth aspect of the present invention, the same effect as that of the eighth aspect can be obtained, and the hollow camshaft and the liquid supply pipe are employed. Since the cooling liquid can be smoothly circulated throughout the shaft, thereby improving the cooling effect, since both the supply and discharge of the cooling liquid are performed at the other end side of the hollow cam shaft, The circulation system of the cooling liquid can be simplified, and the equipment cost can be reduced and the maintenance can be simplified.

According to the apparatus for manufacturing a hollow camshaft according to claim 10 of the present invention, the same effect as in claim 9 can be obtained, and the second liquid supply pipe is employed in the liquid supply means. Accordingly, the processed portion of the hollow camshaft can be intensively cooled, and the cooling effect can be further improved.

According to the apparatus for manufacturing a hollow camshaft according to claim 11 of the present invention, the same effect as in claim 10 can be obtained, and the positional relationship between the heating means and the second liquid supply pipe is established. When the heating means is sequentially moved to a plurality of cam parts arranged at a predetermined interval in the axial direction of the hollow camshaft to perform the overlaying, the second liquid supply pipe The cooling liquid from the inside can always be supplied to the inner surface of the portion to be processed during overlaying,
Since it is not necessary to adjust the position of the liquid supply pipe at all, the build-up of the plurality of cam portions and the cooling of the portions are sequentially and promptly performed, so that further improvement in productivity and the like can be realized. .

According to the apparatus for manufacturing a hollow camshaft according to the twelfth aspect of the present invention, the same effects as in the tenth and eleventh aspects can be obtained, and the outer diameter of the liquid supply pipe of the liquid supply means is made hollow. 1/5 to 1/1 of inner diameter of camshaft
3, the interference between the supply and discharge of the cooling liquid to the hollow camshaft can be minimized, the inside of the hollow camshaft can be filled with the cooling liquid in a short time, and the inside of the hollow camshaft can be filled. In addition to the smooth movement of the liquid supply pipe, the supply and discharge of the cooling liquid to and from the hollow camshaft can be performed extremely smoothly, thereby contributing to further improvement of the cooling effect.

[0035]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a method and an apparatus for manufacturing a hollow camshaft according to the present invention will be described below with reference to the drawings.

A mold 50 shown in FIG. 2 is for forming a hollow camshaft A by plastically processing a steel pipe, and is provided between upper and lower plates 51 and 52 which can be separated from each other.
Four shaft part forming dies 53 to 56, two cam part forming dies 57 and 58, and one journal part forming die 5
9 are arranged. These molding dies 53
No. to No. 59 are divided into several parts in order to enable the release of the hollow camshaft A after molding. Further, a side plate 60 that closes one end of the molding space is provided at one end of the upper and lower plates 51 and 52.

The hollow camshaft A is formed by connecting a steel pipe to the mold 5 described above.
By pressurizing at 0 and filling the steel pipe with the liquid from the opposite side of the side plate 60 by pressure, the cam portion C and the journal portion J are integrally formed on the shaft portion S by the pressure. The hollow camshaft A thus formed has a hollow shaft portion S, a cam portion C and a journal portion J as a whole, and is much lighter than a hollow camshaft in which a cam or a journal piece is provided in a steel pipe. It has been done.

In the case of a hollow camshaft used for an automobile engine, the steel pipe may be, for example, STKM11A.
A seamless steel pipe having an outer diameter of 30 mm and a wall thickness of 3 mm made of (JIS) is used. The hardness of the steel pipe before forming is H
It is about v180. The hollow camshaft A after molding has an outer diameter of the shaft portion S of 26 mm and an inner diameter of 20 mm.
It is.

As shown in FIG. 3, the hollow camshaft A formed as described above is provided with a wear-resistant material on a portion B to be processed from the ramp portion R to the nose top portion N on the outer periphery of the cam portion C. Overlay is performed. The thickness of the overlaid layer is, for example, about 2 mm.

For building up the wear-resistant material, a manufacturing apparatus 1 shown in FIG. 1 is used. In this manufacturing apparatus 1, a frame 3 is erected on a base 2 near one end on the left side of FIG. 1, and an induction motor 5 is provided at one end of the frame 3 via a base 4 and the frame 3 Is provided with a guide portion 6 in the horizontal direction reaching the other end of the base 2. The frame 3 is provided with a scroll chuck 7 for holding one end of the hollow camshaft A, and the guide 6 is provided with a rotary joint 8 for holding the other end of the hollow camshaft A together with the slide body 9. It is provided. FIG. 1 shows a hollow camshaft A in which two cam portions C, C are integrally formed with a shaft portion S.

The scroll chuck 7 is set on the frame 3 so as to face the other end of the base 2 and the rotating shaft 7a
Is rotatably held at the part. At this time, the axial direction of the rotating shaft 7a is parallel to the guiding direction of the guiding unit 6. The scroll chuck 7 is a joint 1 for rotation transmission.
0, the rotating shaft 7a is connected to the output shaft 5a of the induction motor 5, and performs the operation of gripping / releasing the closing means 11 attached to one end of the hollow camshaft A.

The closing means 11 closes one end of the hollow camshaft A, and includes a closing portion 11a which is attached to one end of the hollow camshaft A in a watertight manner, and a holding portion 11b which is held and released by the scroll chuck 7. ing. The scroll chuck 7 holds the hollow camshaft A coaxially by gripping the closing means 11, and is driven to rotate by the induction motor 5 to rotate the hollow camshaft A.
Is rotated about its axis.

The slide body 9 is movable along the guide portion 6 and has a cylindrical member 13 on the table 12 on the upper side thereof, the axial direction of which is the slide body movement direction. , The rotary joint 8 is held via bearings 14 and 14. Further, an operation unit 15 for moving the slide body 9 by a rotation operation is provided at an end of the guide unit 6. As a means for converting the rotational movement of the operation section 15 into a linear movement of the slide body 9, a transmission mechanism including a screw shaft provided along the guide section 6 and a ball screw provided on the slide body 9 is used.

The rotary joint 8 has a cylindrical member 13
It has a rotating ring 16 and a fixed ring 17 inserted therein. The rotating ring 16 is rotatably held by the bearing 14 and has a hollow camshaft A.
Is provided with a connection ring 18 for watertight connection to the other end of the. The fixing ring 17 holds a liquid supply pipe of a liquid supply means described later, and includes a discharge pipe 19 which is a discharge part of the cooling liquid at the other end of the hollow camshaft A.

The liquid supply means 20 includes a hollow camshaft A
The cooling liquid is supplied to the inside of the device. Water or an appropriate refrigerant solution is used as the cooling liquid. The liquid supply means 20 includes first and second liquid supply pipes 21 and 22 inserted into the hollow camshaft A from the other end through the rotary joint 8, and a liquid supply source 23.

The first liquid supply pipe 21 penetrates through the cylindrical member 13 and the fixing ring 17 of the rotary joint 8 in the radial direction, bends 90 degrees inside thereof, and extends to one end side of the hollow camshaft A. Closing means 11
Has an injection hole 21a at the tip end reaching the vicinity of. On the other hand, the second liquid supply pipe 22 is
Is linearly inserted from the end of the cylindrical member 13 and is movably held by a drive mechanism 24 provided at the end of the cylindrical member 13.
The tip has an injection hole 22a. That is, the second
The injection hole 22a of the liquid supply pipe 22 is directed toward the inner surface of the hollow camshaft A, and the inner surface (lower surface) of the portion B to be processed.
The cooling liquid can be directly injected into the liquid. Also,
The drive mechanism 24 includes a motor, a gear, and the like, and reciprocates the second liquid supply pipe 22 in the axial direction.

The liquid supply source 23 includes a tank and a pump for storing a cooling liquid, and supply pipes 25 and 26 connected to the first and second liquid supply pipes 21 and 22.
And a recovery pipe 27 connected to the discharge pipe 19, so that the cooling liquid supplied to the inside of the hollow camshaft A is recovered and circulated again.

Here, in the manufacturing apparatus 1, the first and second liquid supply pipes 21 and 22 in the liquid supply means 20 are provided.
Is 1/5 to 1/3 of the inner diameter of the hollow camshaft A.
And If the diameter is smaller than 1/5, it takes time to fill the inside of the hollow camshaft A with the cooling liquid, and the smooth supply and discharge of the cooling liquid may be impaired. If it is larger than 1/3, the contact between the hollow camshaft A and the liquid supply pipes 21 and 22 is likely to occur, which may make it difficult to move the liquid supply pipes 21 and 22 smoothly, and may also reduce the cooling liquid. This is because there is a risk that the smoothness of supply and discharge of water may be impaired.

Therefore, in this embodiment, since the inner diameter of the shaft portion S of the hollow camshaft A is 20 mm as described above, for example, the outer diameter is 6 mm and the inner diameter is 4.5 m.
m and first and second liquid supply pipes 21 and 22 made of copper
Is used.

In the manufacturing apparatus 1 for the hollow camshaft A having the above structure, when the slide 9 is moved along the guide portion 6, the rotary joint 8 is moved together with the slide 9.
And the first and second liquid supply pipes 21 and 22 move integrally, and the attachment / detachment of the connection ring 18 to / from the hollow camshaft A and the insertion / removal of each liquid supply pipe 21 and 22 are performed. The manufacturing apparatus 1 includes, in addition to the above-described configuration, a heating unit 28 that welds a wear-resistant material to the workpiece B, and a material supply device that supplies the wear-resistant material to the workpiece B. 29.

[0051] As the heating means 28, Nd: YAG laser, CO ₂ laser, the laser emitting apparatus such as a semiconductor laser is used. The heating unit 28 irradiates the workpiece B with a high-density energy beam (laser L) from above. Further, as a wear-resistant material, a carbon content of 1
-4% by weight of a powdered material selected from steel or cast iron materials. The material supply device 29 supplies the powdered wear-resistant material M from above the laser irradiation position in the processing portion B.

Further, in the manufacturing apparatus 1, the speed control and the position control of the heating means 28 are controlled by a control machine 30 such as an NC processing machine.
Is electrically connected to the drive mechanism 24 of the liquid supply pipe 22. When the heating means 28 and the injection holes 22a of the second liquid supply pipe 22 are vertically opposed to each other, and the heating means 28 is moved in the axial direction of the hollow camshaft A, the driving mechanism is synchronized with the movement. Activate 24
Is moved by the same distance in the moving direction of the heating means. Thereby, the positional relationship between the heating means 28 and the ejection holes 22a of the second liquid supply pipe 22 is kept constant.

In the manufacturing apparatus 1 having the above-described configuration, in order to build up the wear-resistant material M on the hollow camshaft A after the plastic working, both ends of the horizontal hollow camshaft A are connected to the scroll chuck 7. After holding with the rotary joint 8, the induction motor 5 is operated,
The hollow camshaft A is rotated about the axis together with the scroll chuck 7 at a speed of 0.4 to 1.4 m / min,
Further, the cooling liquid is supplied into the hollow camshaft A at a flow rate of 10 to 40 l / min through the first and second liquid supply pipes 21 and 22 of the liquid supply means 20.

The cooling liquid flowing through the hollow camshaft A is collected by the liquid supply source 23 through the rotary joint 8, the discharge pipe 19 and the pipe 27, and sent out again to the liquid supply pipes 21 and 22. It is.

Then, while the position 10 mm away from the laser irradiation position is cooled to a temperature of 5 to 140 ° C. by the cooling liquid supplied into the hollow camshaft A, the powder is supplied from the material supply device 29 to the workpiece B. The build-up is performed by supplying the wear-resistant material M, melting the wear-resistant material M by the laser L of the heating means 28, and welding the melted material to the workpiece B.

At this time, in the method and apparatus 1 for manufacturing the hollow camshaft A, the cooling liquid is supplied into the hollow camshaft A, and the position 10 mm away from the laser irradiation position is set to a temperature of 5 to 140 ° C. By cooling,
In addition to preventing the occurrence of poor welding of the wear-resistant material M to the workpiece B due to low temperature, the shaft portion S
Is prevented from softening, and the suppression of this temperature also prevents the solidification rate of the wear-resistant material M from being reduced. As a result, a build-up layer having a sufficient hardness is formed on the cam portion C, and the hollow camshaft A that is lightweight and has excellent wear resistance is obtained.

In the method and apparatus 1 for manufacturing the hollow camshaft A, the heating means 28 and the material supply apparatus 29 are arranged above the hollow camshaft A, and the buildup is performed while rotating the hollow camshaft A. Therefore, the abrasion-resistant material M is supplied to the workpiece B without opposing gravity, and furthermore, since a laser is used as the heating means 28, overlaying with high positioning accuracy is performed. In addition, melting and the like due to excessive heat input are prevented.

At this time, the hollow camshaft A is set to 0.4 to
By building up while rotating around the axis at a speed of 1.4 m / min, when building up from a fixed upper position with respect to the hollow camshaft A as in this embodiment, the build-up layer is formed. The situation where the thickness becomes excessive or insufficient is prevented, and the hollow camshaft A
By performing the overlay while supplying the cooling liquid at a flow rate of 10 to 40 l / min, the cooling effect is prevented from being insufficient and the burden on the circulating system of the cooling liquid is also prevented from increasing. The cooling liquid circulates smoothly.

Further, in the method and apparatus 1 for manufacturing the hollow camshaft A, the liquid supply means 20
The injection means 21a of the first liquid supply pipe 21 is used to close the closing means 11
, The cooling liquid flows from one end to the other end of the hollow camshaft A, and is directed from the injection hole 22a of the second liquid supply pipe 22 toward the inner surface of the workpiece B. The cooling liquid is jetted to cool the entirety, and at the same time, the workpiece B, which has the highest heat,
Is cooled intensively, and the cooling effect is further enhanced.

Moreover, in the method and apparatus 1 for manufacturing the hollow camshaft A, it is not necessary to cool the cooling liquid in advance by a cooling device such as a chiller, and one end of the hollow camshaft A is closed by the closing means. Since it is closed at 11 and both supply and discharge of the cooling liquid are performed at the other end side, the configuration of the circulation system of the cooling liquid is simplified, thereby reducing equipment costs and maintenance. become.

Further, in the manufacturing apparatus 1 for the hollow camshaft A, after the build-up of the left cam portion C in the state shown in FIG. 1 is completed, the heating device 28 and the material supply device 29 are hollowed out by the control device 30. When it is moved in the axial direction of the camshaft A to correspond to the right cam portion C,
The drive mechanism 24 is actuated by the control device 30 to move the second liquid supply pipe 22 in the axial direction, and as shown by the phantom line in FIG. 1, the injection hole 22a of the second liquid supply pipe 22 is moved to the right side. It is made to correspond to the inner surface of the cam portion C.

As described above, in the manufacturing apparatus 1 for the hollow camshaft A, since the heating means 28 and the second liquid supply pipe 22 move while keeping the mutual positional relationship constant, the heating means 28 and the second liquid supply pipe 22 move in the axial direction of the hollow camshaft A. When successively building up the plurality of cam portions C, C arranged, the cooling liquid is always supplied to the inner surface of the portion B to be processed during the build-up, and the second liquid supply pipe 2 is formed.
Since no position adjustment or the like is necessary at all, a plurality of cam portions C
In this case, the buildup and the cooling of the portion are sequentially and promptly performed. Therefore, the productivity of the hollow camshaft A can be improved.

Using the method and apparatus 1 for manufacturing the hollow camshaft A described above, overlaying was performed by changing the flow rates of the wear-resistant material and the cooling liquid. As the heating means, a carbon dioxide laser with a maximum output of 4 kW was used, and the output was 3 kW.
W, and the non-condensed beam is changed to 1 by a cylindrical mirror.
The workpiece was irradiated in a shape of 0 × 0.5 mm, and argon gas was supplied at a flow rate of 25 l / min as a laser shielding gas. As the wear-resistant material, powders of Fe-3.5, C-2.5, and Si-0.08P were used as examples of the present invention, and the same materials as those of the examples, Fe, The ones with different amounts of C and Si and the ones with Cr added were used, the powder supply was constant at 0.6 g / sec, and the processing speed was 0.8 m / min.

Water was used as the cooling liquid. Examples 1-4
In Example 5, circulating water was used as it was, and in Example 5, the circulating water was forcibly cooled to 1 ° C. by a chiller. In addition, as Comparative Example 8, cladding was performed without using a cooling liquid.

During the overlaying, the temperature of the shaft at a position 10 mm away from the laser irradiation position was measured with a thermocouple as the steel pipe temperature. Further, after the build-up processing, the cross-section of the build-up layer was measured by a Vickers hardness meter as the build-up layer hardness, and the cross-section of the shaft portion was measured by a Vickers hardness meter as the steel pipe hardness. The results are shown in the following table.

[0066]

As is clear from the table, in Examples 1 to 4, a sufficient cooling effect was obtained by performing the overlaying at a flow rate of the cooling liquid of 10 to 40 l / min, and the steel pipe temperature was reduced. It was in the range of 90 to 138 ° C., and it was confirmed that a high hardness of the build-up layer was obtained and that there was no extreme decrease in the hardness of the steel pipe. Further, in Example 5, no abnormality was found in the hardness of both the build-up layer and the steel pipe, but it was found that the effect was small compared to the use of the cooling liquid which was forcibly cooled.

In Comparative Examples 1, 2 and 8, since the flow rate of the cooling liquid was reduced or the cooling liquid was not used, a sufficient cooling effect could not be obtained, and the temperature of the steel pipe was increased. It was confirmed that the solidification rate of the layer was slow, and the hardness of the cladding layer and the steel pipe was significantly reduced as compared with the examples. In Comparative Example 3, values comparable to those of the Example were obtained. However, since the flow rate of the cooling liquid was increased, the water pressure in the steel pipe was increased, and it was necessary to take measures for water leakage.

In Comparative Examples 4 and 5, the C content of the wear-resistant material was based on the method of manufacturing the hollow camshaft according to the present invention. In this case, the build-up layer hardness was almost the same as in the examples. It was confirmed. In Comparative Example 6, since the C content of the wear-resistant material was smaller than that of the method of manufacturing the hollow camshaft according to the present invention, it was confirmed that the hardness of the build-up layer and the steel pipe was lower than those of the examples. In Comparative Example 7, since the C content of the wear-resistant material was larger than that of the method for manufacturing the hollow camshaft according to the present invention, the hardness of the build-up layer was extremely high. Solidification cracking occurred and the product quality deteriorated.

As described above, in Examples 1 to 4 based on the method of manufacturing the hollow camshaft according to the present invention, good build-up processing is possible, and the cam portion extends from the ramp portion to the nose top portion. It was confirmed that a sufficient surface hardness of the portion, a sufficient hardness of the shaft portion, and a good build-up quality were obtained.

Further, a single abrasion resistance test was conducted using a part of the hollow camshafts of Examples 1 to 4. The test conditions were as follows.
0kgf, rotation speed 300rpm, oil temperature 50-6
0 ° C. engine oil was supplied, and the test time was 5 hours.

As a result, the abrasion amount was 15 to 35 μm, and it was confirmed that the hollow camshaft for an engine had sufficient wear resistance.

[Brief description of the drawings]

FIG. 1 is an explanatory cross-sectional view showing one embodiment of an apparatus for manufacturing a hollow camshaft according to the present invention.

FIG. 2 is a cross-sectional view illustrating a mold for plastically processing a steel pipe into a hollow camshaft.

FIG. 3 is an end view for explaining a cam portion of the hollow camshaft and a portion to be processed to be overlaid;

[Explanation of symbols]

 Reference Signs List A Hollow camshaft B Workpiece part C Cam part M Wear-resistant material N Nose top part R Lamp part S Shaft part 1 Manufacturing device (for hollow camshaft) 11 Closing means 19 Discharge pipe (discharge part) 20 Liquid supply means 21a 22a injection hole 21 first liquid supply pipe 22 second liquid supply pipe 28 heating means

Claims (12)

[Claims] 1. A steel pipe is plastically worked to form a hollow camshaft integrally provided with a cam portion on a shaft portion, and a wear-resistant material is built up on a portion to be processed from a ramp portion of the cam portion to a nose top portion. A method for manufacturing a hollow camshaft, comprising supplying a cooling liquid to the inside of the hollow camshaft and building up a wear-resistant material. 2. The method for manufacturing a hollow camshaft according to claim 1, wherein a laser is used as means for building up the wear-resistant material. 3. The cladding is performed while cooling a position 10 mm away from a laser irradiation position to a temperature of 5 to 140 ° C. with a cooling liquid supplied into the hollow camshaft. Of manufacturing a hollow camshaft. 4. A wear-resistant material having a carbon content of 1 to 4.
The method for producing a hollow camshaft according to any one of claims 1 to 3, wherein a powder material selected from a steel material or a cast iron material system by weight is used. 5. A hollow camshaft having a diameter of 0.4 to 1.4 m /
The method for manufacturing a hollow camshaft according to any one of claims 1 to 4, wherein the build-up is performed while rotating around an axis at a speed of min. 6. The hollow camshaft according to claim 1, wherein the buildup is performed while supplying a cooling liquid at a flow rate of 10 to 40 l / min into the hollow camshaft. Production method. 7. The method for manufacturing a hollow camshaft according to claim 1, wherein the build-up is performed while spraying a cooling liquid onto an inner surface of a portion to be processed of the hollow camshaft. 8. A hollow camshaft in which a shaft portion and a cam portion are integrally formed by plastically processing a steel pipe,
An apparatus for overlaying a wear-resistant material on a processed portion from a ramp portion of a cam portion to a nose top portion, wherein a heating means for welding the wear-resistant material to the processed portion, and an inner portion of a hollow camshaft. An apparatus for manufacturing a hollow camshaft, characterized by comprising a liquid supply means for supplying a cooling liquid to the hollow camshaft. 9. A liquid supply pipe having closing means for closing one end of the hollow camshaft, wherein the liquid supply means is inserted into the hollow camshaft from the other end and has an injection hole near the closing means. The apparatus for manufacturing a hollow camshaft according to claim 8, further comprising: a cooling liquid discharge portion provided at the other end of the hollow camshaft. 10. The hollow cam according to claim 9, wherein the liquid supply means includes a second liquid supply pipe having an injection hole directed toward an inner surface of a portion to be processed in the hollow camshaft. Shaft manufacturing equipment. 11. The second liquid supply pipe of the liquid supply means,
The apparatus for manufacturing a hollow camshaft according to claim 10, wherein the apparatus is movable in the axial direction of the hollow camshaft together with the heating means. 12. An outer diameter of a liquid supply pipe of a liquid supply means,
The hollow camshaft manufacturing apparatus according to claim 10 or 11, wherein the inner diameter is 1/5 to 1/3 of the inner diameter of the hollow camshaft.