KR20100010947U - End piece assemble structure for assemble type cam shaft - Google Patents

Abstract

The present invention is to force the end piece of the prefabricated camshaft to the hollow shaft by a force-injection method, it is possible to improve the degree of freedom of the shape of the end piece, because it does not perform a separate processing after joining, and can achieve a significant simplification of the manufacturing process The present invention relates to an endpiece assembly structure for a prefabricated camshaft that can improve workability and productivity and stabilize quality.

A fitting hole formed at the end of the cam shaft, a fitting shaft in which a knurled portion is machined on the outer circumferential surface to be firmly fixed by being inserted into the fitting hole by a forced press-fit method, and the fitting shaft is integrally formed on one surface, and the other surface has several holes and grooves. And an end piece formed so as to fasten the bolt for tapping and various components (sprockets, gears, variable valve timing (CVVT) devices, etc.).

In addition, the inner diameter (D1) of the shaft according to the present invention is smaller than the outer diameter (D2) of the fitting shaft 21 of the end piece, the tolerance of the inner diameter of the shaft is Φ 0 ~ +0.1, before the knurling of the fitting shaft 21 Outer diameter tolerance is Φ 0 ~ +0.1, characterized in that after knurling tolerance is Φ +0.3 ~ +0.4.

Camshaft, End Piece, Shaft, Knurled, Forced Press, Friction Welded, Assembly

Description

END PIECE ASSEMBLE STRUCTURE FOR ASSEMBLE TYPE CAM SHAFT}

The present invention relates to an endpiece assembly structure for a prefabricated camshaft, and more particularly, the endpiece of the camshaft is forced to press-fit the endpiece having the knurled portion into the shaft, so that it is coupled to the correct position and does not perform post-processing. The present invention relates to an endpiece assembly structure for a prefabricated camshaft which combines the endpiece in a finished state to simplify the assembly process, thereby improving workability and productivity and stabilizing quality.

In general, the cam shaft (CAM SHAFT) is driven in conjunction with the rotation of the crank shaft to drive the engine, the cam shaft is a plurality of cams of different phases with different phases at predetermined intervals on the outer periphery of the predetermined length and thickness It is provided.

The cam shaft absorbs the rotation of the shaft by arranging the cam on the shaft axis. The exhaust valve is opened and closed sequentially. In the conventional manufacturing method, the shaft and the cam are integrally formed by casting an alloy cast iron to form the shaft and the cam integrally, and the cam (cam lobe) is coupled to a hollow shaft made of a drawn steel pipe. There is a hollow prefabricated type.

Various methods of manufacturing such a conventional cam shaft have been introduced. As an example, there is a method of integrally molding a shaft and a cam as a casting, that is, a cam shaft in which a casting is poured into a mold to form the shaft and a cam integrally. However, a conventional casting method is difficult to automate due to the characteristics of a work process. It is difficult and productive, and the heat treatment process must be performed for surface modification, which makes the work process cumbersome and the use of materials increases due to post-processing, resulting in waste of materials more than necessary. In addition, the heavy weight as a casting material has a limit in responding to the trend toward lighter weight throughout the engine parts, there were a number of disadvantages such as lower fuel efficiency of the engine for internal combustion engines.

In order to solve the problems of the camshaft made of the conventional cast material, a more advanced and developed example is a hollow prefabricated camshaft manufacturing method of separately assembling the camshaft and the hollow shaft made of a drawing pipe.

The hollow prefabricated camshaft can significantly reduce its weight compared to the integral camshaft, and can be assembled by assembling various assembly pieces such as cams, journals, sensors, and driving gears with different materials according to their functions and needs. This is a camshaft used in a vehicle that pursues compactness and light weight.

This is a method of tightly joining the shaft to the cam lobe by heat treatment by inserting the cam into the shaft, which has various advantages such as light weight, high performance, high efficiency, and process improvement. The trend is turning to shafts.

In addition, sprockets and gears for driving the camshaft are fastened to the camshaft in accordance with the rotation of the crankshaft, and variable valve timing (CVVT) for improving engine fuel efficiency and efficiency. ) The device is fastened, and the end piece formed to fasten it is coupled to the end of the cam shaft.

As shown in FIG. 1, the related art combines an end piece 20, which is a round rod material, by a friction welding process with a shaft 10, and sprockets and gears on the other side of the end piece through a machining process. Holes and bolts for bolts are processed, and a number of oil holes and grooves are separately processed to mount a variable valve timing (CVVT) device to make a finished product.

That is, as shown in part A of FIG. 1, when the end piece 20 is rotated at high speed while the shaft 10 and the end piece 20 are fixed on the same axis and closely adhered to each other, frictional heat is generated on the contact surface. In this case, when a constant pressure is applied, the end piece 20 and the tip of the cam shaft 10 are friction-contacted as shown in part B of FIG. 1, and beads are generated on the surface of the pressure-contacting part.

After the joining as above, the friction welding bead portion is removed, and the outer diameter is kept constant as shown in part C of FIG.

As described above, the end piece 20 and the cam shaft 10 are integrally press-bonded, and then transferred to the next machining step, and the end piece 20 is used by using a separate processing device (drilling, tapping, lathe, etc.). A plurality of holes 25 and the step 23 are formed on the other surface of the), and a plurality of grooves 24 are formed on the surface.

However, as described above, the end pieces 20 and the shaft 10 are coupled by friction welding, and the holes 25 and the grooves 24 of the end pieces 20 are centered on any reference angle and distance of the cam shaft. When the end piece 20 is processed in a state in which the end piece 20 is coupled with the shaft 10, the volume of the processing equipment is increased, and the processing time increases, so that individual processing is performed according to each processing process. Facilities are needed.

As described above, when friction welding is performed, a separate process for removing beads generated after friction welding must be performed.

In addition, due to friction welding and instability of the machining, excessive machining allowance of the end piece is required, and the service life of the tool due to the interruption during turning is shortened.

In addition, when processing an end piece of a complex shape, there is a limitation in processing at the exact position due to the unstable processing standards of the processing equipment, there is a problem that a defective product occurs due to a small error in each part during preliminary processing, after processing Difficulties in removing the burr can cause product quality problems.

In addition, since the end piece is assembled by the friction welding method, there are quality problems such as poor welding or breakage of the welded portion.

The present invention is to solve the above problems, the purpose is to combine the end piece to the shaft by a forced press method, it is possible to improve the degree of freedom of the shape of the end piece because it does not perform a separate processing of the end piece after joining To provide an endpiece assembly for a prefabricated camshaft.

In addition, the present invention is a combination of the end piece and the shaft by a forced press method, simplifying the manufacturing process to improve workability and productivity, while minimizing the occurrence of defects, the end for the prefabricated camshaft can stabilize the product quality It is to provide a piece assembly structure.

Referring to the characteristic configuration of the present invention for achieving the above object is as follows.

An endpiece assembly structure for a prefabricated camshaft according to the present invention includes a fitting hole formed at an end of the shaft, a fitting shaft in which a knurling part is processed on an outer circumferential surface of the endpiece so as to be firmly fixed by being inserted into the fitting hole by a forced press-fit method, and the fitting The shaft is integrally formed on one side, and the other side is an end piece formed to fasten several holes, grooves, bolting taps, and various components (sprockets, gears, variable valve timing (CVVT), etc.). It is composed.

In addition, the shaft inner diameter (D1) according to the present invention is smaller than the outer diameter (D2) of the endpiece fitting shaft 21, the tolerance (D2) of the shaft inner diameter is Φ 0 ~ +0.1, of the endpiece fitting shaft 21 The outside diameter tolerance before knurling (D1 ') is (phi) 0-+0.1, and the after knurling tolerance (D1) is (phi) +0.3-+0.4.

The present invention is to couple the end piece to the camshaft by a forced press method, there is a unique effect that can improve the shape freedom of the end piece because it does not perform a separate processing after the coupling.

In addition, the present invention is coupled to the end piece and the cam shaft by a forced press method, while simplifying the manufacturing process to improve the workability and productivity, while minimizing the occurrence of defects there is an effect that can stabilize the product quality. .

In the following, embodiments of the present invention are described with reference to the accompanying drawings.

In the following description of the present invention, if it is determined that a detailed description of a related known function or configuration may unnecessarily obscure the subject matter of the present invention, the detailed description thereof will be omitted. In addition, the terms to be described later are terms set in consideration of functions in the present invention, and these terms may vary depending on the intention or custom of the producer producing the product, and the definition of the terms should be made based on the contents throughout the present specification.

When described with reference to the accompanying drawings showing the subject innovation as follows.

3 is a perspective view showing the assembly structure according to the present invention, Figures 4 and 5 are sectional views showing the assembly structure according to the present invention.

As referred to herein, the subject innovation is the fitting hole 11 is formed at the end of the shaft (10).

One side of the end piece 20 assembled to the end of the shaft 10 is integrally formed with the fitting shaft 21 to be fitted to the fitting hole 11, the fitting on the outer peripheral surface of the fitting shaft 21 A knurled portion 22 for fastening the shaft 21 to the fitting hole 11 by a forced press method is secured.

The knurled portion 22 is preferably a string-type knurled groove in the longitudinal direction, it is preferable to change the spacing and depth of the knurled groove in accordance with the outer diameter of the fitting shaft (21).

In addition, a plurality of holes 25, grooves 24, bolting steps 23, etc. are formed on the other surface of the end piece 20, and are pre-machined before forcibly pressing the end pieces. And a journal unit for fastening parts (sprockets, gears, variable valve timing (CVVT) devices, etc.) to serve as the rotating surface of the camshaft (1).

Referring to the present invention configured as described in detail as follows.

First, the end piece 20 of the present invention is assembled by a camshaft and a forced press method in a state processed into a finished product through a separate processing process.

In order to assemble the end piece 20 at the end of the shaft 10, the end piece 20 is fixed to one side of the assembly apparatus at a reference angle, and the shaft 10 is positioned on the same axis of the end piece 20. .

In this state, when the end piece 20 is pushed toward the shaft 10 side, the fitting shaft 21 is forcibly pressed into the fitting hole 11, and in this case, a knurling portion formed on the outer circumferential surface of the fitting shaft 21. 22 is press-fitted into the inner circumferential surface of the fitting hole 11, so that the coupling force (clamping force) of the fitting shaft 21 and the fitting hole 11 is generated.

On the other hand, the knurled portion 22 is to form a straight knurled groove in the longitudinal direction, that is, the longitudinal direction is coupled to the end piece (20).

And the inner diameter (D1) of the shaft is smaller than the outer diameter (D2) of the fitting shaft 21, the tolerance (D1) of the cam shaft inner diameter is Φ 0 ~ +0.1, the outer diameter tolerance before knurling of the fitting shaft 21 (D2 ㅄ ) Is φ 0 to +0.1, the tolerance after knurling D2 is preferably set to φ +0.3 to +0.4, and the width t of the knurled portion is preferably 15 mm or more.

That is, the indentation amount (D1-D2) = Φ 0.2 to 0.4 = the amount of clamping, when the indentation amount is Φ 0.2 or less, the coupling force of the end piece and the cam shaft is decreased, and when the indentation amount is Φ 0.4 or more, the indentation force is increased during indentation. Deformation occurs in the product.

For example, when D = Φ 17 (endpiece S45C, shaft STKM17) the indentation amount and the torsional force are shown in Table 1.

For example, when D = Φ 17 and the width (t) of the knurled portion fitting shaft of the end piece is 15 mm (KS standard, end piece: carbon steel round bar SM45C, shaft STKM17 material), the forced indentation amount (or clamp amount) as shown in FIG. The separation force of the end piece according to) is shown in Table 1.

Table 1

Indentation amount (Φ) Torsion (bonding force) 0.4 400 Nm ↑ 0.3 350 Nm ↑ 0.2 280 Nm ↑

Therefore, according to the present invention, the end piece 20 is assembled to the end of the shaft 10 by a forced press-fit method, so that a separate processing step after assembly may be omitted to shorten the assembly time.

In addition, since the shape of the end piece before the forced indentation does not change the shape after the indentation, the degree of freedom of processing of the end piece 20 is improved, and various shapes, as well as precise processing, can prevent defective products.

Embodiments of the present invention have been described above with reference to the accompanying drawings.

However, it is to be noted that the present invention is not particularly limited only to the above-described embodiments, and as necessary, various modifications and changes can be made by those skilled in the art within the spirit and spirit of the appended claims.

1 is a perspective view showing a conventional assembly structure.

Figure 2 is a perspective view showing the assembly structure according to the present invention.

3 and 4 is a cross-sectional view showing the assembly structure according to the present invention.

Figure 5 is a schematic diagram for measuring the torsional force (bonding force) of the end piece assembled according to the present invention.

* Description of the symbols for the main parts of the drawings *

1: Cam (lobe)

10: shaft

11: fitting hole

20: end piece

21: fitting axis

22: knurled part

23: Tap

24 Groove

25: Hole

Claims (5)

The fitting hole 11 formed at the end of the shaft 10, the fitting shaft 21 formed to be firmly fixed by being inserted into the fitting hole 11 by a forced injection method, and integrally formed on one surface of the fitting shaft 21. On the other side, the end piece 20 formed to fasten a plurality of holes 25, grooves 24, bolting steps 23 and various components (sprockets, gears, variable valve timing (CVVT) device, etc.) End piece assembly structure for a prefabricated camshaft, characterized in that consisting of. The method of claim 1, The outer peripheral surface of the fitting shaft 21 is composed of a knurling portion 22, the end of the camshaft, characterized in that the knurled portion is formed in the direction in which the end piece 20 is coupled, that is, a straight knurled groove in the longitudinal direction Piece assembly structure. The method of claim 1, The end piece 20 is a prefabricated camshaft endpiece assembly structure, characterized in that the assembly is assembled by a forced press-fit method to the end of the shaft 10 in a completed state. The method of claim 1, The outer diameter of the fitting shaft 21 is an assembly structure for the prefabricated cam shaft, characterized in that configured to be larger than the inner diameter of the shaft (10). The method according to claim 1, The inner diameter D2 of the shaft is smaller than the outer diameter D1 of the fitting shaft 21 of the end piece, but the tolerance D1 of the shaft inner diameter is Φ 0 to +0.1, and the outer diameter tolerance before knurling of the fitting shaft 21 (D2). Iii) is Φ 0 to +0.1, the post-knurling tolerance (D2) is Φ +0.3 to +0.4, and the width t of the knurled portion is 15 mm or more.

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