JP2002241804A - Method for manufacturing bearing with inside- diametrically hollowed intermediate portion - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily manufacture, at a low cost, a bearing with an inside- diametrically hollowed intermediate portion which has low frictional resistance to a shaft and holds lubricating oil in the hollow part. SOLUTION: A pin 2 is provided in the central part of a die 1 having a cylindrical cavity inside, and a lower punch 3 freely slidable along the pin on the inner side of the die is also provided. Metal powder to which a substance causing shrinkage by sintering is added is packed on the top of the lower punch. The top of the metal powder is pressed by means of an upper punch 4 freely slidable along the pin on the inner side of the die and the lower punch to form a metallic green compact K, and the metallic green compact is brought out and sintered to undergo shrinkage. Subsequently, the resultant metallic sintered compact is put in the space formed between the lower punch and the die and pressure is applied again by means of the upper punch and the lower punch to buckle the metallic sintered compact from inside toward outside. By this method, the bearing with an inside-diametrically hollowed intermediate portion in which a hollow part K3 is formed on the inner side of the metallic sintered compact can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a bearing having a hollow inner diameter intermediate portion, and a preferable diameter which is less affected by lubricating oil or the like between a shaft material having an intermediate inner diameter portion and an inserted shaft member. It is a bearing that forms a hollow inner diameter bearing mechanism that secures the difference, has low frictional resistance, can hold lubricating oil in the hollow part, and is inexpensive for products that are effective for speeding up and miniaturizing The present invention relates to a method for manufacturing a hollow bearing having an intermediate inner diameter portion, which can easily and easily manufacture a bearing body.

[0002]

2. Description of the Related Art Conventionally, it is preferable to support a rotating shaft over a long range in order to accurately determine the bearing of the rotating shaft that requires high precision, such as a supercharger bearing of an automobile. When a long bearing having a length longer than the outer diameter is applied, the sliding friction resistance increases in proportion to the long bearing area, the loss due to the frictional resistance of the rotational driving force increases, and it becomes difficult to achieve high-speed rotation.

In order to solve this problem, if the inside of the middle portion of the inner diameter of the bearing is formed in a hollow shape by a drilling tool or the like, oil enters into the hollow portion and the contact with the shaft is reduced. Although the sliding friction resistance is reduced, the number of steps and the cost are increased due to the cutting step and the like.

Another manufacturing method is disclosed in, for example,
In Japanese Patent Application Publication No. 0-122240, a compacting and sintering method is used in which an intermediate portion of an inner diameter is formed into a hollow portion which does not come into contact with a shaft material, and a shaft material sliding portion is formed at each end of the hollow portion. There is a bearing which is a porous structure body, the outer peripheral surface of which is a straight surface, and which connects the hollow portion to the shaft material sliding portion while keeping the hollow portion in a material skin state.

[0005]

However, in the above-mentioned Japanese Patent Application Laid-Open No. 10-122240, a cutting punch and a tapered mold are required in the molding step, and a shape different from that in the molding step is required in the sizing step. Alternatively, since a punch and a mold having a size are required, there is a problem in that the cost of the punch and the mold increases and the bearing itself becomes expensive.

The present invention has solved the above-mentioned problems, and is an inner diameter intermediate hollow bearing capable of holding a lubricating oil in a hollow portion with a small frictional resistance with a shaft. It is an object of the present invention to provide a method for manufacturing a hollow bearing having an intermediate inner diameter, which can easily and inexpensively produce an intermediate hollow bearing having a great effect on downsizing and downsizing.

[0007]

According to a first aspect of the present invention, a pin is provided at a central portion of a die having a cylindrical shape, and the pin and the pin are disposed at the center of the die. A slidable lower punch is provided inside the die, and the upper end of the lower punch is filled with a metal powder to which a substance whose size is shrunk by sintering is added. An upper punch slidable inside the pin and the die is disposed, and the metal powder is pressed by the upper punch and the lower punch to form a metal compact, and the lower punch is moved upward. By taking out the pressed metal molded body, sintering and shrinking the metal molded body, disposing the metal molded body in a space formed between the lower punch and the die, By pressing again by the upper punch and the lower punch, the metal compact is To be compressed is buckled, a method of manufacturing an inner diameter intermediate cavity shaped bearing hollow-shaped portion is formed on the inside of the metal molding.

According to the first aspect of the present invention, there is provided an intermediate bore bearing having an inner diameter and having a small frictional resistance with a shaft and capable of retaining lubricating oil in a hollow portion. An inner diameter intermediate hollow bearing having a great effect can be easily manufactured at low cost.

[0009] In order to solve the above-mentioned technical problem, the invention according to claim 2 is characterized in that the coefficient of friction μ between the metal compact and the upper punch or the lower punch is up to 0.1 and the metal compact is 2. The method according to claim 1, wherein the compression ratio in the vertical direction is 40% or less.

According to the second aspect of the present invention, when the friction coefficient and the compression ratio are within the above ranges, the metal molded body is easily buckled, and a hollow portion is easily formed inside the metal molded body. If the coefficient of friction is greater than 0.1 and the compression ratio is greater than 40%, buckling is not easy in the internal direction.

[0011] In order to solve the above-mentioned technical problems, the invention of claim 2 is characterized in that iron, which is a main component of the metal molded body, contains 0.5 to 6% by weight of nickel. Item 4. A method for manufacturing an inner diameter intermediate hollow bearing according to Item 1.

According to the third aspect of the present invention, the metal compact made of this component is easily densified by high-temperature sintering.

[0013] In order to solve the above-mentioned technical problems, the invention of claim 4 is characterized in that iron which is a main component of the metal molded body contains 0.1 to 0.6% by weight of phosphorus. According to the first aspect of the present invention, a metal compact made of this component is easily densified by performing high-temperature sintering.

[0014]

Embodiments of the present invention will be described below with reference to the drawings. 1 to 6 are process diagrams of a method for manufacturing an inner diameter intermediate hollow bearing according to the present invention.

A die (die) 1 having a cylindrical inside.
And a cylindrical lower punch 3 which is slidable by being inserted into the pin 2 and the inside of the die 1. The lower end 31 of the lower punch 3 is provided with a flange 32 larger than the diameter of the lower punch. The upper end 33 of the lower punch 3 is filled with a metal powder KP to which a substance whose size is shrunk by sintering is added, and the upper end KP1 of the metal powder KP slides inside the pin 2 and the die 1. A free cylindrical upper punch 4 is provided. The metal powder KP becomes a metal compact K by sintering.

In order to shrink the metal compact K, nickel is added to iron as a main component in a powder form and nickel as a component system.
It is advisable to add 5 to 6%. Alternatively, phosphorus may be contained in an amount of 0.1 to 0.6% instead of nickel.

Alternatively, in order to shrink the metal compact K, it is possible to increase the density by sintering at a high temperature of 1150 to 1350 ° C.

Next, as shown in FIG.
And the lower punch 3 sandwich the metal compact K, and 6ton /
It is compressed and pressed at a pressure of cm ^{2 to} 10 ton / cm ² .

Further, as shown in FIG. 3, the upper punch 4 is moved upward, the upward movement of the metal compact K is free, and the lower punch 3 is slid upward. The metal forming body K is taken out.

Next, this metal compact K is placed in the range of 1150 to 135
Sintering is carried out by holding at a temperature condition in the range of 0 ° C. for 20 minutes, so that the metal compact K has a compact ratio of 0.5 to 0.5 mm.
The 8% dimension shrinks.

Next, as shown in FIG. 4, the contracted metal compact K is disposed in a cylindrical space S formed between the lower punch 3 and the die 1.

Further, as shown in FIGS. 5 and 6, the upper punch 4 and the lower punch 3 use ⁷ ton / cm ^{2 to} 10 ton / cm.
The central portion of the cylindrical metal compact K is buckled from the inside to the outside by the pressing force of cm ² .

At this time, if the pressure is less than 7 ton / cm ² , there is a problem that the amount of buckling becomes insufficient and a good cavity shape cannot be obtained. If the pressure is higher than 12 ton / cm ² , there is a problem in productivity in terms of the life of the mold.

By compression-molding the metal compact K, the outer diameter of the outer portion K1 at the center of the metal compact K is enlarged from the inside to the outside and buckled, and comes into contact with the die surface of the die 1. At the same time, the inner diameter of the inner side K3 of the central portion of the metal molded body K is also expanded from the inner side to the outer side, and the center of the metal molded body K is buckled. As a result, as shown in FIG. 5, a hollow portion K3 having a concave shape is formed over the entire inner circumferential surface of the metal molded body K in the circumferential direction.

Next, although not shown, the upper punch 4 is retracted upward and the lower punch 3 is moved upward in the same manner as in FIG. 3 to obtain a metal compact K having a shape as shown in FIG. Is taken out.

As shown in FIGS. 7 and 8, a concave-shaped hollow portion K3 is formed on the inner side K2 of the metal molded body K. FIG. 8 is a diagram in which the metal molded body K is pivotally supported on the shaft 10. The hollow portion K3 is not in contact with the die surface of the die 1 described above. Further, the hollow portion K3 is in a state of a porous sintered surface, and can hold the lubricating oil more favorably.

Except for the hollow portion K3, the portion serving as the bearing portion of the inner side K2 is brought into contact with the die surface of the die 1, so that the dimensional accuracy of the metal formed body K is good and the bearing is good.

In order to shrink the dimensions of the metal compact K, it is possible to adjust the component system, for example, by adding nickel or phosphorus or by using high-temperature sintering to increase the density. In particular, the method of dimensional shrinkage is not limited to the above composition and method.

As described above, according to the present invention, the sintered body obtained from the metal compact K is resized using the same mold as that used for compression molding, and the buckling of the metal compact K is utilized. By forming the hollow portion, the inner diameter intermediate hollow bearing becomes inexpensive. As a result, a mold contact surface having a shape obtained by sizing is obtained, and the mold contact surface has good dimensional accuracy, and the hollow portion and the outer diameter are not in contact with the mold. It can supply oil to the hollow part and is most suitable for bearings.

FIG. 9 shows a metal molded body K manufactured by the above-described manufacturing method.
5 is a graph showing the relationship between the weight percentage and the dimensional shrinkage when nickel is added in an amount of 2 to 8% by weight.

As can be seen from this figure, the dimensional shrinkage ratio increases as the amount of nickel increases, but the effect of dimensional shrinkage does not appear when the nickel content is less than 0.5%. If the nickel content is more than 6%, austenite comes out and the strength is reduced.

FIG. 10 is a graph showing the relationship between the sintering temperature and the dimensional shrinkage when 2% by weight of nickel is added.

As can be seen from this figure, as the sintering temperature increases, the dimensional shrinkage increases, but the temperature decreases from 1150 ° C. to 135 °.
A sintering temperature of 0 ° C. is good. The reason is that if the temperature is lower than 1150 ° C., a problem such as insufficient dimensional shrinkage occurs, and if the temperature is higher than 1350 ° C., the sintering furnace becomes effective.

As described above, the metal compact K is formed by adding 0.5% of nickel for dimensional contraction to 100% by weight of iron.
In addition, 0.5% molybdenum for enhancing the solid solution of the base material and 0.3% of carbon graphite for improving the hardness of the base material may be added. .

The reason for adding nickel is that the solid solution strengthening of nickel and the diffusion rate of iron into nickel are large and the density is increased, resulting in an increase in strength. The reason for adding phosphorus is that phosphorus and iron turn into a eutectic melt, which accelerates the sintering reaction and causes dimensional shrinkage.

In the above description, the dimensional shrinkage rate is
For example, a test piece is 10 mm long x 10 mm wide x 55 mm long
Is prepared, and a dimensional change rate of the length of the test piece is measured to obtain a dimensional shrinkage rate.

FIG. 11 shows the compressibility and the compressibility of a hollow cylinder having a hollow shape (length of the hollow cylinder: inner diameter: outer diameter = 2: 3: 6) when the friction coefficient μ is changed. It is a graph showing the relationship of final inner diameter / initial inner diameter. From this graph, if the coefficient of friction is in a small area,
Buckles in the direction of increasing diameter. That is, the inner diameter increases in the region A at the top of the graph of FIG. Specifically, the friction coefficient μ between the upper end KP1 or the lower end KP2 of the metal molded body K and the end of the upper punch 4 or the lower punch 3 is 0 to 0.1, and the vertical direction to the metal molded body K is When the compression ratio is 40% or less, the inner diameter increases. If the coefficient of friction is greater than 0.1 and the compression ratio is greater than 40%, buckling is not easy in the internal direction.

In the embodiment of the present invention, the upper and lower relations are expressed by upper punch, lower punch, upper direction and lower direction for convenience of explanation. However, the present invention is not limited to the upper and lower relation. It goes without saying that they may be related.

[0039]

As described above, according to the present invention, a pin is provided at the center of a die having a cylindrical inside and a lower punch slidable inside the die and the die. Arrange,
The upper end of the lower punch is filled with a metal powder to which a substance whose size is shrunk by sintering is added, and the upper end of the metal powder is provided with an upper punch slidable inside the pin and the die. A metal compact is formed by pressing the metal powder with the upper punch and the lower punch, and the pressurized metal compact is taken out by moving the lower punch upward, By sintering and shrinking the formed body, the metal formed body is disposed in a space formed between the lower punch and the die, and pressed again by the upper punch and the lower punch,
The metal molded body is buckled from the inside to the outside and compressed,
Since the method is a method of manufacturing a hollow bearing having an intermediate bore having a hollow portion formed inside the metal molded body, the inner bearing has a low frictional resistance with a shaft and can hold lubricating oil in the hollow portion. This is a hollow bearing, and this bearing can easily and inexpensively produce an inner diameter intermediate hollow bearing having a great effect on speeding up and downsizing.

[Brief description of the drawings]

FIG. 1 is a first step for producing a metal compact of the present invention.

FIG. 2 is a second step of manufacturing the metal compact of the present invention.

FIG. 3 is a third step of manufacturing the metal compact of the present invention.

FIG. 4 is a fourth step for producing the metal compact of the present invention.

FIG. 5 is a fifth step for producing the metal compact of the present invention.

FIG. 6 is a sixth step of further compressing the metal compact in the fifth step of manufacturing the metal compact of the present invention.

FIG. 7 is a cross-sectional view of a product obtained by removing the metal molded body of the present invention from a die.

FIG. 8 is a sectional view in which the metal molded body of the present invention is pivotally supported on a shaft.

FIG. 9 is a graph showing a relationship between dimensional shrinkage when nickel is added in an amount of 2 to 8% by weight with respect to 100% by weight of iron which is a main component of the metal molded body of the present invention.

FIG. 10 is a graph showing the relationship between the sintering temperature and the dimensional shrinkage when 2% by weight of nickel is added to the metal compact of the present invention.

FIG. 11 is a diagram showing a hollow shape when the friction coefficient μ is changed (the length of the hollow cylinder at this time:
A graph showing the relationship between the compression ratio and the final inner diameter / initial inner diameter in the compression of a hollow cylinder (inner diameter: outer diameter = 2: 3: 6).

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Die 2 ... Pin 3 ... Lower punch 3 KP ... Metal powder 4 ... Upper punch K ... Metal molded body S ... Space part K3 ... Hollow part

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (reference) F16C 33/14 F16C 33/14 A

Claims (4)

[Claims] 1. A pin is provided at the center of a die having a cylindrical inside, a lower punch slidable inside the pin and the die, and an upper end of the lower punch is provided at the upper end of the lower punch. A metal powder to which a substance whose size is shrunk by sintering is added, and an upper punch slidable inside the pin and the die is provided at an upper end of the metal powder; A metal compact is formed by pressing the metal powder with the lower punch and the lower punch is moved upward, thereby taking out the pressurized metal compact and sintering the metal compact. To shrink,
By disposing the metal molded body in a space formed between the lower punch and the die, and pressing the upper and lower punches again, the metal molded body is buckled from the inside to the outside. A method of manufacturing an inner diameter intermediate hollow bearing in which a hollow portion is formed inside the metal molded body by being compressed. 2. A coefficient of friction μ between the metal compact and the upper punch or the lower punch is up to 0.1, and a compressibility of the metal compact in a vertical direction is 40% or less. The method for manufacturing an inner diameter intermediate hollow bearing according to claim 1. 3. The method according to claim 1, wherein 0.5 to 6% by weight of nickel is contained in iron which is a main component of the metal molded body. 4. The method according to claim 1, wherein phosphorus, which is a main component of the metal molded body, contains 0.1 to 0.6% by weight of phosphorus.