JPS603933A - Production of cam shaft - Google Patents

Abstract

PURPOSE:To produce easily and inexpensively a cam shaft having high accuracy by fitting and pressing a shaft member provided with a fitting part for a cam member and a projection and a cam member provided with a through-hole and a projecting contact surface to each other and subjecting the members to beam welding. CONSTITUTION:A hollow steel pipe is worked to form a fitting part 6 for a cam member and two through-holes 8, 10. The outside circumferential surface of the part 6 is finished by grinding. A pin 12 provided with a projection 14 having an end face 16 at the end is manufactured of a high grade material having resistance to wear and such pin is press-fitted into the holes 8, 10 so as to direct the end face 16 toward the rotating direction of the cam shaft, thereby forming a shaft body 5. On the other hand, a cam member 4 having a through-hole 18 fitting to the part 6, a notch 20 having a plane 26 and a projection 22 having an end face 30 is manufactured. The body 5 and the member 4 are fitted to each other by matching the projection 14 in such a way as to pass through the inside of the notch 2 so that the end face 16 of the projection 22 is pressed to the plane 26 of the notch 20 and the end face 30 of the projection 22 next to said plane across both faces. The contact surfaces are subjected to beam welding to each other, by which the cam shaft is produced.

Description

DETAILED DESCRIPTION OF THE INVENTION This article 8'JJ relates to a method of manufacturing a camshaft, and particularly relates to a method of manufacturing a camshaft by integrating a shaft member and a cam portion 44 that have been manufactured separately. .

There are two methods of manufacturing a camshaft: one is to manufacture the cam part and the shaft part integrally by forging or tl construction, and the other is to manufacture the cam part and the shaft part separately and then fix them together by brazing, etc. There are two known methods of integrating the cam part, but in either method, the cam surface is ground while the cam part and the shaft part are integrated. Since distortion is unavoidable from time to time and it is difficult to completely correct this distortion, the remaining distortion is canceled out by grinding the cam.

In other words, when finishing the cam surface, the cam surface is ground based on the part supported by the bearing of the shaft. Therefore, compared to simply finishing the cam surface by grinding, the cam surface is ground. Generally, when grinding a cam surface, the depth of cut must be set smaller than when grinding a normal cylindrical surface, and the cam is made of high-grade material with excellent wear resistance. This makes grinding work difficult, and if the amount of grinding increases to cancel out the distortion of the shaft, it will take a long time to grind, which inevitably reduces the manufacturing efficiency of the camshaft. Furthermore, since the cam must include a grinding allowance for strain absorption in advance, there is also the problem that the material cost increases accordingly.

In view of the above circumstances, the present invention has been made with the object of providing a method for easily and efficiently manufacturing a camshaft. In order to achieve this object, the camshaft manufacturing method according to the present invention includes a longitudinal member having a circular cross-sectional shape, and a radius of the cam member fitting portion into which the cam member is to be fitted. manufacturing a shaft member having a protrusion facing outward, and at least a contact surface of the protrusion facing the rotational direction of the camshaft and an outer circumferential surface of the cam member fitting portion are finished; (includes a through hole to be fitted into the bl cam member fitting portion and a contact surface that contacts the contact surface of the protrusion, and
A step of manufacturing a cam member in which at least the inner circumferential surface of the through hole L Hakama clip and the outer circumferential side cam surface are finished, and IcI
The cam member and the shaft member are closely fitted in the through hole and the cam member fitting portion, and the contact surfaces are brought into contact with each other; and the step of welding the LD1 contact surfaces to each other. It is characterized by containing.

According to such a camshaft manufacturing method, it is sufficient to perform only necessary processing on the cam member and the shaft member, respectively.
There is no need to perform extra grinding to absorb distortion of the shaft member in the manufacturing process of the cam member (the cam member can be manufactured efficiently, and the assembly to the shaft member can be done by beam welding without distortion). By doing this, high accuracy can be maintained, and the camshaft can be manufactured easily and at low cost.In addition, by doing this, there is no need to provide extra grinding allowance for the cam member. Material yield is improved.Furthermore, since the cam member is finished completely separately from the shaft member, it is possible to grind multiple cam members at once, compared to grinding after integrating the cam member with the shaft member. Therefore, grinding work can be carried out efficiently using small grinding equipment.
The force applied to the shaft member is transmitted to the cam member through the contact surface, but since the rotation direction of the camshaft is unidirectional, it is sufficient that the force is transmitted only through the contact surface. Yes, there is no lack of strength, and
Since the cam part +A and the shaft member are fixed by welding, the vibration characteristics of the completed camshaft are not inferior to conventional ones, even though it is an assembly.

Hereinafter, two or three embodiments of the present invention will be described in detail based on the drawings.

FIG. 1 is a diagram showing a part of a camshaft 1 manufactured by a manufacturing method that is an embodiment of the present invention. This camshaft l is made up of a plurality of cam members 4 fixed to one shaft member 2, but these shaft parts +A2 and cam members 4 are manufactured separately, and then integrated into the camshaft 1. be assembled.

When manufacturing the shaft member 2, first, a hollow longitudinal steel pipe is processed to manufacture the shaft body 5 as shown in FIG. In other words, the outer circumferential surface of the steel pipe is shallowly cut leaving a portion where the cam member 4 is to be fitted to form a cam member fitting part 6 having a larger diameter than the other parts, and further, this fitting part 6 is After forming two diametrically spaced through holes 8 and 10 near the end of the fitting part 6, the outer circumferential surface of the fitting part 6 is finished by grinding. On the other hand, a pin 12 as shown in FIG. 3 is made separately from the shaft body 5, and is press-fitted into the through hole 8.10. The pin 12 is different from the shaft body 5 and is made of high-grade feed rich in wear resistance, that is, special steel, Doug Quill cast iron 9
Alloy cast iron.

It is made by processing ceramics (for example, Zr02), sintered alloy, etc., and is slightly longer than the outer diameter of the fitting part 6, and
It is formed into a cylindrical shape with a diameter slightly larger than the diameter of the through hole 8.10, and one end is notched at a plane containing the axis of the pin 12 and a plane perpendicular to this plane to form a semicircular cross section. A projection 14 is formed. After finishing the end surface 16 of this protrusion 14 on the side that includes the axis of the pin 12 by grinding,
The pin 12 is press-fitted into the through holes 8 and 10. At this time, the fitting portion 6 is press-fitted so that the projection 14 protrudes from the outer circumferential surface of the fitting portion 6 and the end surface 16 thereof faces the direction of rotation of the camshaft 10. In this embodiment, the shaft body 5 and the pin I2 constitute the shaft portion +A2, and the manufacture of the shaft portion +A2 is completed by press-fitting the pin 12. Note that the end surface 16 may be ground after the pin 12 is press-fitted into the through holes 8 and 10.

On the other hand, when manufacturing the cam member 4, first, if the material is special steel, ductile cast iron, etc., precision casting is used, or if it is sintered alloy or ceramics, the material is placed in a mold. After compression molding, the material is sintered at high temperature to produce a material having a cross-sectional shape as shown in FIG. In addition, there is a through hole 18 that is fitted with the shaft member 2, and a notch 20 that is open over the entire length of the through hole 18.
and a notch 20 on one end face relative to the center line of this end face.
A material is manufactured that has protrusions 22 located symmetrically with the 22 and has a predetermined grinding allowance.

As shown in FIG. 5, the diameter of the through hole 18 at both ends is preferably slightly smaller than the outer diameter of the fitting part 6, and the diameter at the middle part is preferably larger than the diameter at both ends. becomes a relief portion 24 when fitting the cam member 4 to the shaft member 2. Further, the notch 20 is provided in a size that allows the passage of the protrusion 14 from the inner circumferential surface of the through hole 18 to the protrusion side of the cam member 4, and is formed on a surface that divides the cam member 4 symmetrically in the axial direction. It is provided with a certain plane 26 and is formed to be located on the opposite side of the plane 26 with respect to the rotational direction of the camshaft. Therefore, as described above, the protrusion 22, which is located at a position symmetrical to the notch 20 with respect to the center line of the end surface of the cam member 4, is located on the rotational direction side of the re-camshaft with respect to this center line, and on the notch 20 side. The end face 30 of the notch 2
They are adjacent to each other on the same plane as the plane 26 of 0.

After manufacturing the above-mentioned material, heat treatment is performed if necessary, and the inner peripheral surface of the through hole 18, the flat surface 2G of the notch 20, the end surface 30 of the protrusion 22, and the surface of the outer cam IfX are ground and finished. Manufacturing of the cam member 4 is completed.

After manufacturing the shaft member 2 and the cam member 4 separately in this way, the hook saw that heats the cam member 4 cools the shaft portion ItA2, or both, to create a temperature difference between the two, and The through hole 18 of the cam member 4 and the fitting portion 6 of the shaft member 2 are fitted together using the accompanying expansion and contraction. At this time, the shaft member 2 and the cam member 4 are fitted so that the phases of the shaft member 2 and the cam member 4 are aligned so that the protrusion 14 protruding from the outer peripheral surface of the shaft member 2 passes through the notch 20 of the cam member 4, and the through hole 18 of the cam member 4 is inserted. While fitting into the outer peripheral surface of the fitting part 6, the end surface 16 of the protrusion 14 is fitted into the flat surface 2 of the notch 2 () as shown in FIGS. 6 and 7.
6 and the end surface 30 of the protrusion 22 following this, and are brought into contact with each other across both sides. Then, when the shaft member 2 or the cam part +A4 returns to the temperature before the temperature difference was applied, that is, room temperature, they return to their original size and are tightly fitted in the fitting part 6 and the through hole 18. becomes.

In this state, as shown in FIG. 7, the contact surfaces of the protrusion 14 and the cam member 4 are partially joined by beam welding using a laser beam 34 (an electron beam may also be used), which enables strain-free welding, to fix the two. Thus, an integrated camshaft 1 is completed.

If the shaft member 2 and the cam part +A4 are manufactured completely separately in this way and then integrated by beam welding, no distortion will occur in the shaft member 2 and the cam member 4. It is possible to obtain an integrated camshaft without grinding the surface. Therefore, the shaft member 2 and the cam member 4
In order to achieve this, it is sufficient to perform only the required processing on each of the camshafts, and since no extra processing is required, it is possible to manufacture them efficiently, and as a result, the work efficiency of camshaft manufacturing can be improved.

Furthermore, in this embodiment, since the shaft member 2 is manufactured by processing a hollow steel pipe, it is possible to reduce the weight, and
The grinding of the cam member fitting portion 6 can also be carried out efficiently because it is simple cylindrical grinding of a material that is easy to grind. Further, only the cam member 4 and the pin 12 need be made of ILI-grade materials, and additional grinding is not required, making it possible to manufacture the device at low cost. In addition, since the shaft Ql material 2 and the cam member 4 are manufactured separately in this way, there is a large degree of freedom in material selection, and it is possible to manufacture them using materials suitable for each purpose, reducing weight and manufacturing costs. In addition to reduction, there is also the advantage of extending the camshaft's running life.

In addition, in this embodiment, since the pin 12 constituting the shaft member 2 is made of the same material as the cam member 4, the protrusion 1 of the pin 12
4 and the cam member 4 are easily welded, but the protrusion 14 and the cam member 4 do not necessarily have to be made of the same material, and may be of any material that can be beam-welded to each other.

Furthermore, the driving force applied to the shaft member 2 is transmitted to the cam member 4 from the contact surface between the protrusion 14 and the cam member 4, but since the rotational direction of the camshaft is unidirectional, this force is sufficiently transmitted. It can be transmitted with no shortage of strength. However, if the pins 12 are press-fitted into both ends of the fitting part 6 of the shaft body 5, and the two protrusions 14 are brought into contact with the cam member 4, -1M GIQ, the force can be truly transmitted. be able to.

FIGS. 8 to 10 show another cam shirt 40 manufactured by the camshaft manufacturing method according to the present invention. In this cam shirt I-40, the structures of the shaft member 42 and cam member 44 are different from those of the previous embodiment. That is, regarding the shaft member 42, the through holes 46 and 48 into which the pin 12 is press-fitted are formed at an intermediate position in the axial direction of the cam member fitting part 49, and the cam part'
rA'44δ differs from the previous embodiments in that it itself has an assembled structure.

When manufacturing the cam member 44, first, a steel plate is squeeze-molded to form a bottomed cylindrical member 50, and the bottoms of the two cylindrical members 50 are brought together and spot welded to form a rim portion. The cam member body 52 is an integral cam member body having a web portion and a web portion. Then, a thin belt 54 made of a high-grade material with excellent wear resistance is fitted onto the outer peripheral surface of the rim portion of the main body 52. In this case, the belt 54 is heated to expand and fit into the main body 52, and when the heald 54 returns to its original temperature, it is tightly fitted into the main body 52. In this state, it is desirable to beam-weld the fitting surfaces to prevent slippage.

A through hole 55 into which the shaft member 42 is fitted into the web portion of the main body 52, and a cam member 4 extending from the inner circumferential surface of the through hole 55.
A notch 56 with a rectangular cross section extending toward the protruding portion of No. 4 is formed. Like the notch 20, this notch 56 is formed by cutting out a plane including the center line of the through hole 18 in the direction opposite to the rotational direction of the camshaft, and the end face 58. Outer peripheral surface of belt 54 and through hole 55
The cam member 44 is completed by grinding the inner circumferential surface of the cam member 44.

After manufacturing the shaft member 42 and the cam member 44 as described above, they are made into an integrated camshaft in the same manner as in the previous embodiment, but in this embodiment, the cam member main body 52 is attached to the rim. Since it is a thin-walled member consisting of a section and a web section, it is lighter in weight, and
A high-grade material with excellent abrasion resistance can be used for the belt 54, which has the unique effect of reducing material costs.

Note that in the above two embodiments, the pin 12 may be formed integrally with the shaft body 5, and the pin 12 may be formed integrally with the shaft body 5, and the pin 12 may be formed integrally with the shaft body 5. It is also possible to omit the finishing of the end surfaces 58 and the like and finish the outer peripheral cam surfaces of the cam members 4 and 44 using these as a reference.

Although no other examples will be given, it goes without saying that the present invention can be implemented with various modifications and improvements based on the knowledge of those skilled in the art without departing from the scope of the claims.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing the main parts of a camshaft manufactured by a manufacturing method according to an embodiment of the present invention. 2 is a partially cutaway front view showing the main part of the shaft body of the shaft member configuring the cam shirt 1- shown in FIG. 1, and FIG.
It is a front view which shows the pin which should be press-fitted into the shaft main body shown in the figure. FIGS. 4 and 5 are a front view and a side view (partially in section) showing a cam member to be fitted to the shaft member. 6th
7 and 7 are a side sectional view and a main part front view (partially cut away) -ζ showing a state in which the shaft member and the cam member are integrated into an integrated camshaft. FIG. 8 to FIG. 1O are perspective views and side views 101, respectively, showing the main parts of another camshaft manufactured by the shaft manufacturing method according to the present invention.
They are a top view and a front view of main parts (partially cut away). t, 4O: Cam shirt I-2, 42: Shaft month 4.44:
Cup, part 4', I' 5: Shaft body 6.49: Cam member fitting part 8, l (1, 18, 46, 48, 55: Through hole I2: Pin 14: Projection 16.30.58: End face 20.5G: Notch 22: Projection 26: Flat surface 50: Cylindrical part Applicant: Toyota Motor Corporation

Claims (1)

[Scope of Claims] A method for manufacturing a camshaft by integrating a shaft opening and a cam member that are manufactured separately, wherein the camshaft is a longitudinal member with a circular cross-sectional shape, and the cam member is fitted. A cam member fitting portion to be mated and a radially outward protrusion, and at least a contact surface of the protrusion facing the rotational direction of the camshaft and an outer circumferential surface of the cam member fitting portion are provided. a step of manufacturing a finished shaft member, the step comprising: a through hole to be fitted into the cam member fitting portion; and a contact surface contacting the contact surface of the protrusion; manufacturing a cam member in which the inner peripheral surface and the cam surface on the outer peripheral side are finished, and the cam member and the shaft member are connected to the through hole and the cam member fitting portion. A method of manufacturing a camshaft, comprising the steps of: closely fitting the abutting surfaces together, and beam welding the abutting surfaces together.