JPH04162952A - Hollow cam shaft and its manufacture - Google Patents

Abstract

PURPOSE:To obtain high strength and lightening to a hollow cam shaft by applying groove machining only to part corresponding to a shaft bearing part at front end face, etc., divided to shaft direction of outer peripheral face in the hollow shaft, forming as cast-in welding to the corresponding shaft bearing part, etc., and making under the hollow shaft condition to the part except welding position. CONSTITUTION:Only to the parts corresponding to the shaft bearing part 6 at front end face, a shaft bearing part 7 for rear end face, cam part 8 and journal part 9, divided to the shaft direction of outer peripheral face in the steel-made hollow shaft 10, machining to groove and recessed and projected parts is applied with knurling tool, etc., having the fixed width. The shaft bearing part for front end face, etc., corresponding to only the groove and recessed and projected positions in the above hollow shaft, are integrally formed as cast-in welding to the above hollow shaft. The shaft part except the above welding position, is under condition of the above steel-made hollow shaft. By this method, the machining man-hour is drastically reduced, and by making the shaft part the hollow pipe exposing part, this is made to lightening and the hollow cam shaft having sufficient strength can be obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a hollow camshaft and a manufacturing method thereof;
In particular, it relates to a hollow camshaft whose shaft portion is a steel hollow shaft.

Conventional technology Conventional hollow camshafts and their manufacturing methods include:
For example, a) a method of assembling a cam piece, a journal piece, etc. onto a hollow shaft by sintering or bulge molding, etc. b) a method of forming the entire shape of the camshaft by casting using a core in the hollow part C) a method of forming the entire shape of the camshaft There are various methods such as forming the entire shape by casting or forging and drilling a hollow hole using a machine tool.

Further, as a document on a conventional method for manufacturing a hollow camshaft, Japanese Patent Application Laid-open No. 104660/1983 is cited.

JP-A-62-104861, JP-A-63-128
No. 09, etc., and Japanese Patent Application Laid-Open No. 2-84228 is a document on the fugitive model casting method.

Problems to be Solved by the Invention Each of the above manufacturing means a), b), and c) had the following problems.

In the method a), the cam piece and journal piece are often made of compacted powder and are easily disintegrated, and the method of assembling these pieces with the hollow shaft is also difficult.
The problem arises that the accuracy of the products that have been released after 8 years is also inferior. Furthermore, in the bulge machining method, pre-treatment (heat treatment) and the like are performed to make the hollow shaft easier to process, so although it is easier to process, it has the disadvantage of becoming weaker in terms of strength. In addition, the aforementioned sintering, bulge processing, etc. require a lot of equipment cost.
This also has the disadvantage of high cost.

In the method b), the core remains inside the hollow camshaft after the hollow camshaft is cast, and it is difficult to remove the core.

Means C) has the disadvantage that machining of the hollow hole in the camshaft requires a large number of man-hours.

Therefore, it has been desired to realize a hollow camshaft and a method for manufacturing the same that does not have the above-mentioned drawbacks.

Means for Solving the Problems The present invention has been able to solve the above-mentioned problems by providing the following hollow camshaft and method for manufacturing the same. In other words, l) Grooves formed by knurling or the like at a constant width only in the parts corresponding to the front end face bearing part, rear end face bearing part, cam part and journal part which are divided in the axial direction of the outer circumferential surface of the steel hollow shaft; The hollow shaft is machined with concave and convex portions, and the corresponding front end face bearing portion, rear end face bearing portion, cam portion, and journal portion are integrally cast and welded to the hollow shaft only at the grooves and the concave and convex portions of the hollow shaft. 2) The hollow camshaft is configured such that the shaft portion other than the welded part of the casting remains the steel hollow shaft, and 2) the outer peripheral surface of the hollow shaft made of M is divided in the axial direction. Only the parts corresponding to the front end face bearing part, rear end face bearing part, cam part, and journal part are subjected to plastic processing of grooves and unevenness by knurling etc. to a certain width, and a preformed center is applied to the holes at both ends of the hollow shaft. A front end face bearing portion that corresponds only to the grooves and the irregularities machined portions by inserting the cores and setting the plastically worked hollow shaft in a mold for a fugitive model molding machine.

The rear end face bearing part, cam part, and journal part are each formed from styrofoam, and then the front end face bearing part, the rear end face bearing part, the cam part, and the journal part are respectively formed on predetermined portions of the hollow shaft by fugitive model casting. This is a method for manufacturing a hollow camshaft in which the shape of the camshaft is formed by casting welding, and the shaft portion remains a hollow steel shaft.

The outer peripheral surface of the working steel hollow shaft is divided in the axial direction into a plurality of straight grooves made of knurling or the like of a constant width (see Figure 1), diagonal grooves (see Figure 1 B and C), and twill grooves. (1st
(see Figure A) or plastic working such as serrations or concave grooves or convex grooves by pressing (see Figure 1 E), the front end face bearing portion and rear end face bearing portion are provided only at the above-mentioned processing locations, respectively. Since the cam part and the journal part are welded together, each welded part has a rotation prevention effect and a welding effect, and is reliably integrated with the steel hollow shaft. Since the rest of the shaft remains a hollow steel shaft, we are able to provide a hollow camshaft that has both the strength required for a cam and the lightweight and great strength of a hollow shaft. In addition, the outer circumferential surface of the steel hollow shaft is machined with straight grooves, diagonal grooves, la-th grooves, or serrations of a constant width to a certain width, or concave or convex portions are formed by pressing. Using the fugitive model casting method, the front end bearing portion and the rear end bearing portion were formed only in the above-mentioned processed portions, respectively.

The hollow camshaft manufacturing method that efficiently forms the cam part and the journal part by casting welding ensures that the casting welding part is integrated with the steel hollow shaft through a combination of detouring effect and welding effect. To provide a hollow camshaft which has both the necessary strength as a cam and is lightweight and has great strength as a hollow shaft, since the steel hollow shaft can be left as the shaft other than the welded part. This is what was created.

Example The present invention will be explained in detail below with reference to embodiments shown in the drawings.

(1) About the hollow camshaft As shown in Fig. 1, a cylindrical steel hollow shaft 10
A plurality of grooves and uneven processing areas 11.11 are divided in the axial direction of the outer circumferential surface 23 (for example, the front end face bearing part corresponding part 12, the rear end face bearing part corresponding part 13, the cam part corresponding part 21).
．． 21.Only in the corresponding part of the journal 22.22), a straight groove 27 (see diagram 3N1) and a diagonal groove 28° 29 (see figure 1 B or C) made of a knurling or the like with a constant width in the axial direction.
, a twill groove 3° (see Fig. 's1 A), or a concave groove 24, a convex groove 25 (see Fig. E's1), etc., are plastically worked by pressing, etc., and the groove of the hollow shaft 1° is , uneven processing portion 11.11 (i.e., the above-mentioned 12.13.21,
22, 24, 25) only, the corresponding front end bearing part (front end bearing model 6 in Figure 2, 's6)
shape), rear end face bearing (same shape as rear end face bearing part 7 in Figures 2 and 6), cam part (same shape as cam part model 8.8 in Figures 2 and 6), and journal part (same shape as the journal part model 9.9 in FIGS. 2 and 6) are integrally cast-welded to the hollow shaft 10, and the shaft parts 31.31 other than the cast-welded parts are made of the steel hollow shaft. The hollow camshaft in which the shaft 10 is free is an embodiment of the hollow camshaft of the present invention. Shape 2 of the cam
The location of the journal has not been specified, but of course,
The axial position of the cam, the angle with respect to the axis, the axial position of the journal, etc., depend on the rotating machine in which the camshaft is used,
Of course, it differs depending on the engine, etc.

(2) Regarding the method for manufacturing a hollow camshaft As shown in FIG. 1, the outer peripheral surface 2 of a cylindrical steel hollow shaft 10
3, the predetermined grooves, uneven processing parts 11.11 (for example, the front end face bearing part corresponding part 12, the rear end face bearing part corresponding part 13, the cam part corresponding parts 21, 21, the journal part corresponding part 22.22). Straight grooves 27 (see first diagram), diagonal grooves 28, 29 made of knurling etc. with a constant width in the axial direction
(see Figure 1 B or C), plastic working such as twill groove 30 (see Figure 1 A) or plastic working such as concave groove 24 and convex groove 25 (see Figure 1 E) by pressing etc. Next, 'M
As shown in FIG. 2, center cores 15 and 16, which have been previously formed by shell cores, for example, are inserted into the hollow shaft 10, and the hollow shaft 10 is attached to the fixed side of the fugitive model molding machine, as shown in FIG. It is set between a fixed side mold 1 for fugitive model molding and a movable side mold 2 for fugitive model molding attached to the movable side of the same molding machine. The hollow shaft 10 can be set between the molds 1.2 by supporting center cores 15.16 fitted into both ends of the shaft 10, but as shown in Figs. As shown in figure s4, after forming the camshaft as a casting, the hollow shaft 10
The receiving portions 4, 4 are provided in advance on the stationary mold 1 in a protruding manner at a position corresponding to the shaft portion 31 (see FIG. 6) where the shank is directly exposed.
This is done by placing the hollow shaft 10 on the shaft. Note that instead of the receiving part 4.4, a magnet 34 is embedded in the mold engraving recess 3 as shown in Figure 'M5, and a magnet 34 is embedded in the hollow shaft 10.
may be adsorbed.

As shown in FIG. 2, the mold is divided into two along a vertical plane including the axis X-X line of the set hollow shaft 10, and the movable side mold 2 for fugitive model molding is the fixed side mold 2 for fugitive model molding. Type 1
It is said to be movable back and forth.

In addition, in the case where the fixed side mold for evanescent model molding is placed at the bottom and the movable side mold for fugitive model molding is placed at the top, and the movable side mold is movable up and down, the above-mentioned receiving part is not necessary.

Center core 15 inserted into both end holes of hollow shaft 10
．． It is also a good idea to reinforce the IS with a core metal, etc., if necessary.

Further, the end faces of the hollow shaft 10 are exposed on both end faces of the front end bearing model 6 and the rear end bearing model 7, and the diameter of the hollow hole at both ends of the molded fugitive model and the end face diameter of the hollow shaft 1o are the same diameter. In this case, the shape of the engraving recess 3 of the mold is made as shown in Fig. 383 without setting the center cores 15 and 16 in the holes at both ends of the hollow shaft 10 in advance, and after molding, the center cores 15 and 16 are set in the holes at both ends of the fugitive model. Center core 1
5°16 can also be fitted and set.

As shown in FIGS. 2 and 3, the above-mentioned fixed side mold for evanescent model molding and movable side mold for evanescent model molding have a shape in which the camshaft shape is divided into two along the axis X-X. The engraving recesses 3 are formed respectively. After placing the plastically worked hollow shaft 10 on the receiving parts 4, 4 of the mold as described above, when the fugitive model molding machine is operated, the movable mold 2 is brought into close contact with the fixed mold 1. The engraved recesses 3, 3 formed in both molds 1.2 are formed around the hollow shaft 10 at predetermined intervals on the fugitive model molding machine foot, and each cavity has a respective ejection passage. The styrofoam 9 is connected to the mortar mouth 5 via 32 .

After the fixed side mold 1 and the movable side mold 2 are brought into close contact with each other, Styrofoam is jetted into the winter cavity through the Styrofoam spout 5 and the spout passage 32 to fill it, and at the same time the heated steam spout 14.14 Heated steam is ejected into each cavity filled with expanded polystyrene to form a fugitive model within each cavity, and a front end bearing model 6 is formed on the front end bearing part 12 of the hollow shaft 10. , a rear end face bearing model 7 is placed on the rear end face bearing part 13, a cam part model 8 is placed on the cam part 21, and a journal part model 9 is placed on the journal part 22, respectively. The hollow camshaft is formed as shown in FIG. 2, and a fugitive model 33 of the hollow camshaft is formed as shown in FIG. Note that the peripheral surface of the hollow shaft 10 of the shaft portion 31 remains exposed.

Next, as shown in Figure 's7, the aforementioned center core 15
．． The front end face bearing part model 6, the rear end face bearing part model 7, the cam part truss type 8, and the journal part truss type 9 of the fugitive model 33 formed on the hollow shaft 10 inserted into the runner 16 are attached to the runner 18. It is assembled and connected to the sprue cup 17 via the runner 18. In addition, FIG. 7 shows a case where the adjacent cam part model 8 and journal part model 9 are connected, and in this case, the cam part model 8 and the journal part model 9 that are connected are partially connected. It is sufficient if road 18 is connected.

After the above-mentioned fugitive model 33, runner 18, and sprue cup 17 are assembled, the fugitive model 33 that has been assembled is placed in the flask 19 as shown in FIG. Model casting River sand 20 is filled and molded. After the above-mentioned molding work is completed, the molten metal is poured into the sprue cup 17, and the front end bearing model 6, the rear end bearing model 7, and the cam part mold 8 are formed.
, a front end face bearing part, a rear end face bearing part, a cam part, and a journal part are integrally formed with the hollow shaft 10 at the disappearing positions of the journal part model 9, and after cooling, the frame is dismantled to form the required hollow camshaft. obtain.

The obtained hollow camshaft has the same shape as the vanishing model shown in FIG. 6 and the southern shape.

Effects of the Invention The present invention provides grooves or irregularities formed by knurling or the like having a constant width in a plurality of parts of the outer circumferential surface of a hollow steel shaft, which are divided in the axial direction and where the front end face bearing, the rear end face bearing, the cam, and the journal are located. For those that have been subjected to plastic processing,
Since the front end face bearing part, rear end face bearing part, cam part, and journal part are cast-all welded only at the above-mentioned processing locations, the welded parts around each part have the effect of preventing rotation and the effect of ensuring welding. It is firmly welded together with the hollow steel shaft, and the shaft portion other than the welded parts remains the hollow steel shaft, so it has the necessary strength as a cam, and is lightweight and lightweight as a hollow shaft. It has become possible to provide a hollow camshaft that has the effect of having great strength at a low cost. Straight grooves and diagonal grooves with knurling etc. at a constant width.

Recesses caused by processing or pressing of twill grooves or serrations,
By performing plastic working on the convex parts, etc., and welding the front end face bearing part, the rear end face bearing part, the cam part, and the journal part only in the processed parts using fugitive model casting, weld the front end face bearing part, the rear end face bearing part, the cam part, and the journal part. The welded part is firmly and integrally welded to the hollow shaft, and together with the detouring effect of the plastically worked part, it has the necessary strength as a cam, and by using a steel hollow vibrator as the basic shaft part. , it becomes possible to significantly reduce the processing man-hours,
In addition, by using the fugitive model casting method, there is no generation of cracks in each casting part, the finishing work is simplified, and the shaft part can be made into a hollow vibrator exposed part, making it possible to achieve a thorough weight reduction. This results in a hollow camshaft that has sufficient overall strength and reduces the weight and manufacturing costs, which in turn helps speed up and save energy in rotating machinery and motors to which the hollow camshaft is installed. The following effects can be obtained.

[Brief explanation of the drawing]

FIGS. 1A, B, C, D, and E are perspective views of embodiments of hollow shafts with grooves and unevenness processed at predetermined positions, respectively (A:
(B, C: diagonal grooves, D: straight grooves, E: convex grooves and concave grooves), Fig. 2 shows an example of a mold that is vertically divided into two parts, showing the state after molding the fugitive model. A horizontal sectional view of the hollow shaft axis, Fig. 3 is a perspective view of an embodiment of the stationary side mold of a mold that is vertically divided into two at the hollow shaft axis, and Fig. 4 is only the stationary side mold in Fig. 2. FIG. 5 is a partial sectional view of a case where a magnet is buried in place of the receiving part in FIG. , FIG. 7 is an axial vertical cross-sectional view of an embodiment showing the molding inside the flask of the expanded polystyrene model. 6: Front end face bearing model, 7: Rear end face bearing model, 8: Cam part model, 9: Journal part model, 10: Hollow shaft, 11+fi, uneven machining area, 12: Applicable part of front end face bearing, 13: The corresponding part of the rear end bearing part! 5
．． 16: Center core, 21: Cam part corresponding part, 22: Disternal part corresponding part, 23: Outer peripheral surface, 24: Concave groove, 25: Convex groove, 27: Straight groove, 2B, 29: Diagonal groove, 30: Ayame groove, 31; shaft.

Claims (2)

[Claims] (1) Grooves and irregularities with constant width knurling, etc. only on the parts corresponding to the front end face bearing, rear end face bearing, cam and journal parts that are divided in the axial direction of the outer circumferential surface of the steel hollow shaft. A front end face bearing part, a rear end face bearing part, a cam part, and a journal part are integrally cast and welded to the hollow shaft only at the grooves and irregularities of the hollow shaft. . A hollow camshaft, characterized in that the shaft portion other than the part where the casting is welded remains the steel hollow shaft. (2) Grooves with knurling, etc. of a constant width, or unevenness are formed only in the parts corresponding to the front end bearing, rear end bearing, cam, and journal parts, which are divided in the axial direction of the outer circumferential surface of the steel hollow shaft. The hollow shaft is subjected to plastic working, and pre-formed center cores are fitted into the holes at both ends of the hollow shaft, and the plastically worked hollow shaft is set in a die for a fugitive model molding machine, and the groove and unevenness are processed. Foamed polystyrene models of the front end bearing, rear end bearing, cam, and journal parts are respectively formed in the corresponding locations, and then, by fugitive model casting, the front end bearing, rear end A method for manufacturing a hollow camshaft, characterized in that the shapes of a bearing part, a cam part, and a journal part are formed by casting welding, and the shaft part remains a hollow steel shaft.