KR101776428B1

KR101776428B1 - Method for manufacturing sprocket having different materials

Info

Publication number: KR101776428B1
Application number: KR1020150176867A
Authority: KR
Inventors: 이진현; 조영철; 곽형석
Original assignee: 현대자동차주식회사
Priority date: 2015-12-11
Filing date: 2015-12-11
Publication date: 2017-09-07
Also published as: KR20170069536A

Abstract

The present invention relates to a heterogeneous material sprocket having a boss portion connected to a shaft and a toothed portion engaged with a chain made of different powders and a method of manufacturing the same.
The method of manufacturing a heterogeneous material sprocket according to the present invention is characterized in that the base 21, the lower outer shape 23, the lower inner shape 24 and the lower outer shape 23 from the core 22, A first powder injecting step (S110) for relatively lowering the first outer powder (23) and injecting a first powder (31) to be a tooth (12) into the sprocket (10) A second powder injecting step of relatively lowering the lower inner mold 24 and injecting a second powder 32 to be the boss portion 11 of the sprocket 10 into a space formed by lowering the lower inner mold 24, (S140) of lowering the upper outer shape (25) and the upper inner shape (26) to pressurize and sinter the first powder (31) and the second powder (32) (Step S150) of raising the upper outer shape 25 and the upper inner shape 26 to take out the molded sprocket 10 It characterized.

Description

METHOD FOR MANUFACTURING SPROCKET HAVING DIFFERENT MATERIALS [0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sprocket for use in power transmission in a vehicle and a method of manufacturing the sprocket, and more particularly, to a sprocket which is made of different powder materials and which has a boss portion connected to a shaft, And a manufacturing method thereof.

And various power transmission means for transmitting power to the engine of the vehicle.

The sprocket 10 driven by the chain or the sprocket 10 driven by the chain must have a higher hardness and strength than the boss 11 connected to the shaft so that the sprocket 10 engages with the chain. 10, the teeth 12 are subjected to a high-frequency heat treatment to increase hardness and strength.

The sprocket 10 is manufactured by sintering an alloy powder of iron (Fe), copper (Cu), and carbon (C) using a metal mold and then subjecting the teeth 12 to high frequency heat treatment.

However, since the conventional sprocket and the method of manufacturing the same require high frequency heat treatment for the teeth 12 after sintering, time and cost are required accordingly.

On the other hand, the following prior art documents disclose techniques relating to a 'chain sprocket and a manufacturing method thereof'.

KR 10-0223465 B1

The present invention has been made to solve the above-mentioned problems, and it is an object of the present invention to provide a dental material sprocket and a dental material sprocket which have different tooth and boss materials so that the teeth can exhibit desired hardness and strength without heat treatment, And a manufacturing method thereof.

Another object of the present invention is to provide a heterogeneous material sprocket wherein the boss portion and the toothed portion have different density gradients even if they are different from each other, and a manufacturing method thereof.

According to another aspect of the present invention, there is provided a sprocket comprising a boss portion fixed to a shaft and a toothed portion formed on an outer side of the boss portion and engaged with a chain, Are characterized in that they are formed by integrally sintering different powders.

The boss portion is formed of a powder composed of iron, copper and carbon, and the tooth portion is formed of powder composed of iron, chromium, molybdenum and carbon.

The boss portion is a mixed powder of iron powder, copper powder and carbon powder.

The tooth portion is formed of a powder of an alloy of iron, chromium, molybdenum and carbon.

And the tooth portion is filled with more powder than the boss portion and is sintered.

Wherein the boss portion and the tooth portion are formed by sintering with a powder at a weight ratio of 5.2: 5.5.

The boss portion has a structure in which pearlite and ferrite are mixed, and the tooth portion has a martensite structure.

According to another aspect of the present invention, there is provided a method for manufacturing a heterogeneous material sprocket comprising a base, a core movably mounted on the base, and a plurality of sprockets disposed on the outer side of the core at a lower portion of the base, A method of manufacturing a sprocket by injecting powder into a mold including a lower outer shape and a lower inner shape and an upper outer shape and an upper inner shape which are vertically arranged above the lower outer shape and the lower inner shape, A first powder input step of relatively lowering the lower outer shape from the base, the lower outer shape, the lower inner shape, and the core, and injecting a first powder to be formed in the sprocket into a space formed by lowering the lower outer shape; And lowering the lower inner mold relatively to lower the second powder to be the boss portion of the sprocket, A press forming step of pressing and sintering the first powder and the second powder under a predetermined pressure by lowering the upper outer shape and the upper inner shape; And a de-molding step of raising the inner shape to take out the molded sprocket.

And a preliminary forming step of lowering the upper outer shape and pressing the first powder filled in the upper end of the lower outer shape between the first powder injecting step and the second powder injecting step.

The first powder is composed of iron, chromium, molybdenum and carbon, and the second powder is composed of iron, copper and carbon.

The first powder is a powder of an alloy of iron, chromium, molybdenum and carbon.

And the second powder is a mixed powder of iron powder, copper powder and carbon powder.

And the first powder and the second powder are filled in the lower outer shape and the lower inner shape at a ratio of 5.5: 5.2.

In the first powder injecting step, the lower outer shape is maintained, and the base, the core and the lower inner mold are raised so that the lower outer shape is lower than the base so that a space is formed in which the powder can be injected into the upper part of the lower outer shape .

In the second powder injecting step, the lower inner mold is maintained, and the base, the core and the lower outer mold are raised so that the lower inner mold is lower than the base so that a space is formed in which the powder can be put into the upper portion of the lower inner mold. .

According to the heterogeneous material sprocket having the above-described structure and the method of manufacturing the same, the hardness and the strength of the toothed portion can be improved by sintering the first powder and the second powder together in the mold in the process of manufacturing the sprocket So that the heat treatment process requiring time and cost due to the additional heat treatment becomes unnecessary for the hardness and strength of the tooth portion.

Further, by making the amounts of powder constituting the boss portion and the tooth portion different from each other, a density gradient does not occur between the boss portion and the tooth portion after the sprocket is completed, even though the materials of the boss portion and the tooth portion are different from each other.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a partially cutaway perspective view of a disparate material sprocket according to the present invention;
2 is a flowchart showing a method of manufacturing a heterogeneous material sprocket according to the present invention.
3 is a process diagram showing one embodiment of a method for manufacturing a heterogeneous material sprocket according to the present invention.
4 is a process diagram showing another embodiment of a method for manufacturing a heterogeneous material sprocket according to the present invention.
FIGS. 5 and 6 are electron microscope photographs of the texture of the interface between the teeth and the boss portion in the heterogeneous material sprocket according to the present invention. FIG.
7 is a graph showing the hardness of an interface in a heterogeneous material sprocket according to the present invention.
FIG. 8 is an electron micrograph of a diffused state at the interface between a tooth and a boss portion in a heterogeneous material sprocket according to the present invention. FIG.
9 is a graph showing the distribution of respective components at the interface between the teeth and the boss portion in the different material sprocket according to the present invention.

Hereinafter, a heterogeneous material sprocket and a method of manufacturing the same according to the present invention will be described in detail with reference to the accompanying drawings.

The different material sprocket according to the present invention is characterized in that the boss portion 11 connected to the shaft at the center in the sprocket 10 and the tooth portion 12 formed at the outer side of the boss portion 11 and engaged with the chain are made of different materials .

The sprocket 10 is manufactured by using the different powder from the boss portion 11 and the tooth portion 12 by the manufacturing method described below so that the boss portion 11 and the tooth portion 12 Performance can be achieved.

It is preferable that the first powder 31 and the second powder 32 are filled in different packing ratios. For example, the first powder 31 and the second powder 32 are filled at a weight ratio of 5.5: 5.2. This is to prevent a density gradient between the teeth 12 and the boss 11 when molding is completed.

Here, the first powder 31 is a powder composed of iron (Fe), chromium (Cr), molybdenum (Mo), and carbon (C), and the second powder 32 is iron (Cu) and carbon (C). Particularly, the first powder 31 is powder of an alloy of iron (Fe), chromium (Cr), molybdenum (Mo) and carbon (C), and the second powder 32 is powder of iron (Fe) (Cu) powder and carbon (C) powder. That is, the first powder 31 contains iron, chromium (Cr), molybdenum (Mo), and carbon (C) in a mixed state, and the second powder 32 is iron Fe), copper (Cu), and carbon (C) are mixed.

For example, the first powder 31 may include 0.4 wt% to 0.6 wt% of carbon (C), 0.4 wt% to 0.6 wt% of molybdenum (Mo), 2.7 wt% to 3.3 wt% of chromium (Cr) Fe), and the second powder 32 may be composed of 0.7wt% to 10wt% of carbon (C), 2.5wt% to 3.5wt% of copper (Cu), and the balance of iron (Fe).

A method of manufacturing a heterogeneous material sprocket according to the present invention will now be described.

A method of manufacturing a heterogeneous material sprocket according to the present invention is manufactured by a mold that can be lifted up and down on a base (21).

The structure of the mold for manufacturing the dissimilar material sprocket 10 includes a base 21, a core 22 vertically installed on the base 21, A lower outer shape 23 and a lower inner shape 24 disposed on the outer side of the core so as to be able to ascend and descend from the outside of the core 22 and an upper outer shape 23 and a lower inner shape 24, An upper profile 25 and an upper profile 26,

The lower outer shape 23 and the lower inner shape 24 are sequentially lower than the base 21 so that the space where the powder can be injected into the upper outer shape 23 and the upper inner shape 24 The powder that becomes the material of the boss portion 11 and the tooth portion 12 of the sprocket 10 is sequentially placed in a space formed in the upper outer shape 23 and the upper outer shape 23, And the powder is pressurized by the upper outer shape 25 and the upper inner shape 26 to be molded.

To this end, the present invention is characterized in that the lower outer contour 23 is relatively lowered from the base 21, the lower outer contour 23, the lower inner contour 24 and the core 22 arranged at the same height, A first powder injecting step S110 for injecting a first powder 31 to be a tooth 12 into the sprocket 10 into a space formed by lowering the lower outer contour 23, A second powder injecting step (S130) of relatively lowering the second inner powder (24) and injecting a second powder (32) to be the boss portion (11) of the sprocket (10) into a space formed by lowering the inner bottom (24) A press forming step S140 of lowering the upper outer shape 25 and the upper inner mold 26 to press and sinter the first powder 31 and the second powder 32 in a predetermined manner; And removing the formed sprocket 10 by raising the upper inner mold 26 (S150).

The first powder injecting step S110 may relatively lower one of the lower outer contour 23 and the lower inner contour 24 so that the powder to be one of the boss portion 11 and the tooth portion 12 .

For example, in the first powder injecting step S110, the lower outer contour 23 is relatively lowered and the first powder 31 to be the teeth 12 is inserted into the lower outer contour 23 of the sprocket 10, So that it can be inserted into a space formed by lowering of

Wherein the base (21), the core (22), the lower outer shape (23) and the lower inner shape (24) are aligned at the same height and the upper and lower inner shapes (25, 26) The core 22 and the lower end 24 in the state in which the lower outer contour 23 is positioned above the upper inner contour 24 and the lower inner contour 24, When the lower outer contour 23 is relatively lowered with respect to the base 21, a space is formed in the upper portion of the lower outer contour 23 by that much.

In this way, when the lower outer contour 23 relatively descends to create a space, the first powder 31 is introduced. The first powder 31 is filled by moving the first powder 31 in the space above the base 21 in a state covered with a cup or the like. Here, the first powder 31 is a powder to be the teeth 12 in the sprocket 10.

Herein, the lower outer contour 23 is relatively lowered to mean that the first powder 31 is filled above the lower outer contour 23, The lower outer contour 23 is in place and the base 21 and the core 22 and the lower inner mold 24 are raised so that the lower contour 23 ) May be lowered. This is because the remaining elements except for the lower outer shape 23 are raised to secure a time for the first powder 31 to be filled in the space to have a uniform interface.

In the second powder injecting step S130, the powder to be the remaining powder, that is, the boss portion 11, is introduced into the space formed in the upper portion of the lower inner mold 24 after lowering the lower inner mold 24 relatively.

Since the lower outer contour 23 is relatively lowered and the first powder 31 to be the tooth 12 is put in the first powder injecting step S110, in the second powder injecting step S130, The inner mold 24 is relatively lowered, and the second powder 32 to be the boss portion 11 is introduced.

In the second powder applying step S130, the lower in-mold 24 is actually lowered or the base 21, the core 22 and the lower outer contour 23 are raised so that the second powder 32, To secure the space to be filled. That is, since the upper end of the lower inner mold 24 is at the same height as the base 21 in the first powder injecting step S110, the second powder 32 may be injected in the second powder injecting step S130 The lower inner mold 24 should be lower than the base 21.

The first powder injecting step (S110) and the second powder injecting step (S130) may be performed in a reversed order. That is, the lower outer contour 23 is relatively lowered so as to insert the first powder 31 to be the tooth portion 12 of the sprocket 10, and then the second powder 31 to be the boss portion 11 32 are lowered. In order to insert the second powder 32 to be the boss portion 11, the lower inner mold 24 is first lowered relatively to fill the second powder 32, and then the lower outer mold 23 is lowered 1 powder 31 may be filled.

On the other hand, the amount of the powder to be input in the first powder injecting step (S110) and the second powder applying step (S130) is larger than the volume of the space in which the first powder (31) and the second powder (32) After the amount is supplied, the remaining amount is collected to prevent mixing of the first powder 31 and the second powder 32. For example, after the first powder 31 is overfilled to a predetermined height, the second powder 32 is filled, and the upper and lower outer shapes 25 and 23 are raised by a portion of the overfilled height, If the powder dosing device is withdrawn, it can be raised by the remaining height.

In addition, the first powder 31 and the second powder 32 may be filled in different packing ratios. For example, the first powder 31 and the second powder 32 are filled at a weight ratio of 5.5: 5.2. This is to prevent a density gradient between the teeth 12 and the boss 11 when molding is completed.

The preliminary forming step S120 may be performed between the first powder applying step (S110) and the second powder applying step (S130). In the present invention, the first powder (31) and the second powder (32) may be pressure-molded all at once in a state where all of the powders are put in. However, The outer shape (25) or the upper inner mold (26) descends to press the powder that has been introduced first.

For example, when the first powder 31 is first put on the lower outer contour 23, the upper contour 25 descends to preform the first powder 31.

The preforming step (S120) is performed because when the first powder 31 and the second powder 32 are molded at the same pressure, cracks are generated in the sintering due to the difference in density of each material, Since the preformed preform serves as a guide and thereafter the density difference due to the molding pressure between powders can be minimized when the powder is introduced.

The press forming step S140 is completed by performing the second powder applying step S130 so that the lower outer contour 23 and the lower inner contour 24 of the first powder 31 and the second powder 32, The upper outer shape 25 and the upper inner mold 26 are lowered to form the first powder 31 and the second powder 32 by pressurization. At this time, the pressing amount through the upper outer shape 25 and the upper inner shape 26 is the same.

When the first outer powder 25 and the second inner powder 26 descend to press the first powder 31 and the second powder 32, the first powder 31 and the second powder 32, Are formed into the teeth (12) and boss portions (11) of the sprocket (10), respectively, while being sintered.

In the demolding step (S150), the upper outer shape (25) and the upper inner shape (26) are raised to take out the molded sprocket (10).

The above procedure is repeated to produce a heterogeneous material sprocket.

Meanwhile, characteristics of the sprocket 10 manufactured by the method of manufacturing a heterogeneous material sprocket according to the present invention will be described below.

As shown in FIG. 5, the boss portion 11 becomes a structure in which perlite and ferrite are mixed, and the tooth portion 12 becomes a martensite structure. The martensite structure is a structure having high hardness and strength. Since the teeth 12 of the sprocket 10 have the martensite structure, the teeth 12 can exhibit high hardness and strength.

This can be confirmed in FIG. That is, in FIG. 6, the teeth of the teeth 12 are shown to be more dense, and the hardness and strength of the teeth 12 are high.

5 and 6, a sintered neck is formed at the interface, that is, at the interface between the boss portion 11 and the tooth portion 12. The first powder 31 and the second powder 32 It can be seen that the sintering is good.

7, when the hardness of the interface section is measured, the hardness of the tooth portion 12 is higher than that of the boss portion 11, and the area of transition from the tooth portion 12 to the boss portion 11, That is, it can be seen that the hardness is reduced rapidly at the interface.

Further, pores are removed by diffusion at the interface by sintering. The pores generated at the interface between the dissimilar powders are removed due to the presence of the Cu-rich region around the diffusion region while copper (Cu) is sintered.

9, it can be seen that the elements constituting the first powder 31 and the second powder 32 are diffused around the interface.

10: Sprocket
11: Boss part
12:
21: Base
22: Core
23: Lower profile
24:
25: Upper contour
26:
31: First powder
32: Second powder
S110: First powder input step
S120: preforming step
S130: Second powder input step
S140: Press forming step
S150: De-molding step

Claims

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A lower outer shape and a lower inner shape disposed on the outer side of the core at a lower portion of the base so as to be able to ascend and descend from the outside of the core, A method of manufacturing a sprocket by injecting powder into a mold including an upper outer shape and an upper inner shape,
The lower outer shape and the lower outer shape are relatively lowered from the base, the lower outer shape, the core arranged at the same height, and the first powder to be added to the sprocket is inserted into the space formed by lowering the lower outer shape 1 powder input step,
A second powder injecting step of relatively lowering the lower inner mold and injecting a second powder to be a boss portion of the sprocket into a space formed by lowering the lower inner mold;
A press-molding step of lowering the upper outer shape and the upper inner shape so that the first powder and the second powder are pressed and sintered in a predetermined manner;
And removing the molded sprocket by raising the upper outer shape and the upper inner shape.

9. The method of claim 8,
Further comprising a preforming step of lowering the upper outer shape and pressing the first powder filled in the upper end of the lower outer shape between the first powder injecting step and the second powder injecting step, &Lt; / RTI >

9. The method of claim 8,
Wherein the first powder comprises iron, chromium, molybdenum, and carbon,
Wherein the second powder comprises iron, copper, and carbon. &Lt; RTI ID = 0.0 > 11. < / RTI >

9. The method of claim 8,
Wherein the first powder is a powder of an alloy of iron, chromium, molybdenum, and carbon.

9. The method of claim 8,
Wherein the second powder is a mixed powder of iron powder, copper powder, and carbon powder.

9. The method of claim 8,
Wherein the first powder and the second powder are filled in the lower outer shape and the lower inner shape at a ratio of 5.5: 5.2.

9. The method of claim 8,
In the first powder injecting step, the lower outer shape is maintained, and the base, the core and the lower inner mold are raised so that the lower outer shape is lower than the base so that a space is formed in which the powder can be injected into the upper part of the lower outer shape Wherein the sprocket is made of a metal.

9. The method of claim 8,
In the second powder injecting step, the lower inner mold is maintained, and the base, the core and the lower outer mold are raised so that the lower inner mold is lower than the base so that a space is formed in which the powder can be put into the upper portion of the lower inner mold. Wherein the sprocket is made of a metal.