JP3212111B2 - Manufacturing method of composite sintered parts - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION This invention provides a mechanical element shaped like especially outer periphery of the flange portion has a plurality of flange portions in the cylindrical portion sprocket or gear Oh <br/> Rui is a cam or the like The present invention relates to a method for manufacturing a composite sintered part, which is manufactured by sintering a sintered part having a plurality of compacts fitted together.

[0002]

2. Description of the Related Art Conventionally, as shown in FIG. 12, for example, a cylindrical portion 4 has a plurality of flange portions 5a, 5b.
Since it is difficult to form a sintered part having a shape such that the outer periphery of 5b is a sprocket , gear, cam, or the like, the cylindrical part 4 is divided into two parts by a concentric circle inside and outside. Each body is molded into a shape that can be extracted from the mold, and these parts are fitted together before sintering, and these parts are integrated using the difference in expansion and contraction caused by sintering or diffusion between members. And the like.

As means for improving the bonding strength of such a sintered composite part, for example, the following means has been proposed in the case of an iron-based sintered alloy as an example.

[0004] That is, as disclosed in Japanese Patent Publication No. 62-57682 and the like, there is a method in which a fitting dimension between a shaft member and an outer member of a green compact is set to a specified amount of tight fit state, As disclosed in JP-A-35-442, a method in which carbon is added to a shaft member and the amount of carbon is increased by 0.2% or more than that of an outer member in order to utilize expansion and contraction, and Japanese Patent Publication No. 63-15961. As disclosed in the official gazette, there has been proposed, for example, a method in which reduced iron powder is used in which 50% or more by weight of iron powder forming both members is formed from a green compact as the roughness of the fitting surface.

Further, as disclosed in Japanese Patent Application Laid-Open No. 64-11913, there is a method utilizing diffusion promotion in which a diffusion promoting element such as copper powder or graphite powder is added to both members. Furthermore, a method in which a recess is formed in at least one of the molded bodies using a brazing material, and the recess is filled with a brazing material compact and sintered is disclosed in Japanese Patent Publication No. Sho 57-4443.
No. 3 publication.

In order to increase the coupling force by increasing the fitting contact area, a concave portion is formed on one of the divided surfaces, and a convex portion which fits with the concave portion is formed on the other of the divided surfaces, and expansion or sintering during sintering is performed. The one that obtains the binding force by the difference in contraction is disclosed in
No. 7441 discloses this.

[0007]

As described above, the fitting between the shaft member 2 made of the compact and the outer member 3 is performed in consideration of the dimensional change due to interference fit or sintering. , 3 are set, so that if one of the members is tilted at the beginning of press-fitting and during press-fitting, the members 2 and 3 will be cracked. It is necessary to press-fit.

The variation in the size of the green compact in the pressing direction when the members 2 and 3 are molded is about 0.2 mm when compacted by a normal press. In the case where the two parts 2 and 3 are fitted by abutting against the flange portion 5b, the variation in the entire length of the component is about 0.4 mm at the maximum.

The present invention has been made in view of such circumstances, and has as its object to facilitate the workability of fitting the shaft member and the outer member and to improve the accuracy of the overall length dimension. It is an object of the present invention to provide a method for producing a composite sintered product that can be formed in a composite.

[0010]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a compacted shaft member and a compacted outer member fitted to the shaft member. In the method of manufacturing a composite sintered body that is sintered and integrated in a fitted state with each other, the shaft surface of the shaft member is formed as a small-diameter tapered surface on a tip end to be fitted, and the bearing surface of the outer member is The inlet side to be fitted is formed as a large diameter tapered surface, and each taper ratio is 10/100 to 60/100.

The shaft surface of the shaft member is formed as a small-diameter taper surface on the end surface side of the cylindrical portion, and the bearing surface of the outer member is formed as a large-diameter taper surface on the cylindrical surface end surface side. Is between 10/100 and 60/100,
The outer member is formed to have a smaller taper ratio than the shaft member.

Furthermore, the tapered surfaces of the shaft member and the outer member each have a stepped portion and have two tapered surfaces, and the inclination of the stepped portion with respect to the axis is different between the shaft member and the outer member. and fitting the both members in the axial direction pressure <br/> press and, if necessary, the contact portion is deformed, collapsed, object dimensions
It is characterized by ensuring the law . Further, when the green compact of the shaft member and the outer member is fitted, at least one of the flange portion of the shaft member and the end surface of the outer member opposed to each other, a ring that is annularly or annularly connected at regular intervals. the provided both members to form and pressed push axially fitted both members,必
The protrusion is deformed or collapsed as necessary, and a desired dimension is secured .

[0013] Also, along the axial direction of the fitting surface of the one member.
One or more protrusions protruding toward the other member are formed, and the protrusions are formed in a trapezoidal shape having a small width at the end face side of the tubular portion and a large width at the other end side. On the surface, along the axial direction, a concave streak having a shape fitted in the width direction of the convex streak and separated in the height direction is formed along the axial direction at a position corresponding to the convex streak, and additional concave streaks are formed on the circumference. It is characterized by being formed at equal intervals.

Means for utilizing expansion or contraction of the inner and outer members or promoting diffusion are conventionally used.

In the case where the tapered surface is formed stepwise in the middle of the axial direction, the stepped portion of the two members is so pressed that any part of the stepped portion comes into contact with the stepped portion of the mating member when press-fitted. The inclination of the part surface is formed differently.

When the cylindrical fitting surface is provided with an axial concave and convex ridges for fitting, two or four ridges may be provided at equal intervals on the circumference.

The difference (gap) between the height of the ridge and the depth of the ridge is
The ridge is set so that the top of the ridge is not pressed against the bottom of the ridge by sintering, and may be about several μm to 500 μm.

It is sufficient that the height of the ridge is about 1 mm. This is because the cylindrical portion to be fitted is not so thick, so making the height of the ridge too high will reduce the thickness of the cylindrical portion of the concave ridge.

The widths of the plurality of ridges may be uniform, but if the number of teeth of the two flanges is odd or even or if there is a predetermined phase, the width of one ridge is increased. Forming them is convenient for phase matching during assembly.

The width of the concave ridge and the convex ridge is formed such that the concave ridge is wide and the convex ridge is narrow at the tip of the fitting.

The concave ridge of the other member, which does not mesh with the convex ridge, only needs to have a depth (gap) enough to be separated from the cylindrical surface of the one member, and is formed flat when the other member is on the axial side. be able to. In this case, since the concave stripes do not fit, the width need not necessarily be tapered. 10/10 taper ratio
If it is smaller than 0, it is not preferable because the powder is caught in the notch formed in the tapered portion of the mold during compacting, which hinders the operation of the mold and causes abrasion of the mold.

If the taper ratio is larger than 60/100, the shaft member and the outer member move in a direction in which the shaft member and the outer member are separated in the axial direction during fitting and sintering, so that the axial dimensional accuracy and the joining are improved. It is not preferable because it tends to be insufficient.

In addition, the taper ratio cannot be made too large due to the thickness and axial length of the fitting portion. Therefore,
The taper ratio is preferably 15/100 to 20/100 (vertical angle of about 8 to 12 degrees), although it depends on the thickness of the cylindrical portion into which both members are fitted.

In the case where a shaft member made of a compact having a flange at one end of a cylindrical portion and an outer member made of a compact having a flange at one end of the cylindrical portion, both members are fitted. When sintering is performed, a tendency is observed that the joining force of the cylindrical portion is lower than that near the flange portion of the outer member.

This is considered to be because the cylindrical portion is thinner than the flange portion, and the gripping force during the compact fitting and sintering is reduced. Therefore, the shaft surface of the shaft member compact is a tapered surface with a small diameter on the end surface side of the cylindrical portion, and the bearing surface of the outer member compact is a tapered surface with a large diameter on the end surface side of the cylindrical portion. Similarly, if the outer member is formed to have a taper ratio smaller than that of the shaft member while being set to 10/100 to 60/100, the joining force of the outer member can be improved when both members of the compact are fitted. .

When the tapered surface is formed in two steps by the stepped portion, the inclination of the stepped portion with respect to the axis is formed differently between the shaft member and the outer member, and when it is fitted and pressed in the axial direction, After the root or corner of one step abuts against the surface of the other step, the root or corner is deformed or collapsed by weak pressure. It is possible to secure the target dimensions without causing the problem.

When a projection is provided on at least one of the opposing end surfaces of the two members and is pressed in the axial direction in a fitted state, the projection is deformed or collapsed by a weak pressure. By pressing until it reaches, the target dimensions can be ensured without causing cracks in the member.

A gap is provided between the top of the ridge of one member and the bottom of the ridge that meshes with the ridge, and a gap is formed between the other ridge and the cylindrical surface of the one member. By forming the arrangement at a substantially equal distance around the circumference of the fitting surface, the distortion deformation of the two members in the vicinity is absorbed, the roundness of the component is improved, and quenching is performed. Has the effect of reducing the concentration of quenching stress from the gaps and making it harder for quenching cracks to occur in the member. These are not limited to one outer member, and the same applies when there are two or more outer members.

[0029]

According to the present invention, since a composite sintered part is produced with the fitting surface of the two members, the shaft member and the outer member, being tapered, there is a gap between the two members at the entrance of the fitting. Insertion becomes easier.

Further, the shaft surface of the green compact of the shaft member has a small-diameter taper surface on the end surface side of the cylindrical portion, and the bearing surface of the green compact of the outer member has a large-diameter taper surface on the end surface side of the cylindrical portion. Since the outer member is formed to have a smaller taper ratio than the shaft member, it is possible to improve the joining force of the outer member when both members of the compact are fitted.

Further, the tapered surface is formed in two steps with a step, and the inclination of the step with respect to the axis is formed differently between the shaft member and the outer member. Therefore, if the member is pressed down to the total length of the assembly, the target size can be secured without causing cracks in the member.

Further, when the molded body having the projections provided on at least one of the opposite end surfaces of both members is pressed in the axial direction in a state of being fitted, if the molded body is pressed to the full length of the assembly, The target dimensions can be secured without causing cracks in the member.

Also, a gap is provided between the top of the ridge of one member and the bottom of the ridge that meshes with the ridge, and a gap is formed between the other ridge and the cylindrical surface of the one member. In the case where quenching is performed by forming the arrangement at substantially equal distances around the circumference of the fitting surface, the concentration of quenching stress is reduced from the gaps, and hardening cracks are less likely to occur in the member.

[0034]

Embodiments of the present invention will be described below in detail with reference to the drawings.

The same members as in the prior art will be described with the same reference numerals.

The flange portions 5a and 5b are provided at both ends as shown in FIG.
Is a sample.

The shaft member 2 and the outer member 3 are formed from a mixture of iron powder and copper powder and graphite powder, and the amount of graphite of the shaft member 2 is smaller than that of the outer member 3 by 0.1%. 3% and the amount of copper are increased by 2%, but the density of both members 2 and 3 is 6.7 g.
/ Cm ³ .

FIG. 1 shows the tapered surfaces 10 and 11 in an exaggerated manner, and the taper ratio of the two members 2 and 3 is 15 /.
It is assumed to be 100.

When the two members 2 and 3 are fitted and pressed, the cylindrical portion 4 of the outer member 3 is attached to the surface of the flange 5b of the shaft member 2.
The dimensions of the tapered surfaces 10 and 11 are adjusted so that the end surfaces of the tapered surfaces 10 and 11 slightly come into contact with each other to form an interference fit. With this configuration, the first fitting of the assembly of the two members 2 and 3 can be facilitated, and the tapered surfaces 10 and
Since the fitting is performed in accordance with 11, it is possible to assemble with high accuracy.

FIG. 2 is a cross-sectional view schematically showing a state after the extraction of the outer member 3 after the green compacting.

The outer lower punch 21, the inner lower punch 22, and the core 23 are fitted to the die 20 in this order.
1, a tapered portion 21a is formed. Then, first, the inner lower punch 22 relatively rises and the powder 3 becomes the outer member 3.
The notch 25 is formed between the outer lower punch 21 and the inner lower punch 22 as shown in the drawing. When the powder enters the notch 25 and the inner lower punch 22 descends relatively to the outer lower punch 21, the powder bites into a narrow portion of the notch 25, and as the molding continues, the operation of the mold deteriorates, and Wear is significant. This phenomenon becomes remarkable when the taper ratio is smaller than 10/100.

FIG. 3A shows a state in which the compacts 2 ', 3' are fitted, and FIG. 3B shows a state in which the compacts 2 ', 3' are fitted during sintering. It shows the state.

That is, when sintering the fitted compacts 2 ′, 3 ′, the compacts 2 serving as the shaft member 2 are strengthened in order to strengthen the tight fit between the compacts 2 ′, 3 ′. As shown in FIG. 3 (b), when the green compact 2 ′ and the green compact 3 ′ serving as the outer member 3 are contracted, the green compacts 2 ′ and 3 ′ slide in the axial direction on the mating surfaces of each other. A phenomenon of escape is observed. This means that the taper ratio is 6
It is remarkable when it is larger than 0/100.

FIG. 4 shows an embodiment in which a sprocket having a flange portion 5a at both ends of a cylindrical portion 4 is divided into two members inside and outside and is fitted in a tapered shape. The shaft member 2 is indicated by a dotted line, and the outer member 3
It is.

The taper ratio of the outer member 3 is set slightly smaller than the taper ratio of the shaft member 2.

When the two members 2 and 3 are fitted and pressed in a predetermined position in the axial direction, the fitting of the cylindrical portion 4 of the outer member 3 becomes large.

When the taper ratios of the two members 2 and 3 are set to be the same, the cylindrical portion 4 of the outer member 3 is thin, so that it is easy to escape to the outside when it is press-fitted. Although the joining force of the two and three does not increase, the average value of the joining force is increased and the variation is reduced with such a configuration.

FIG. 5A shows a configuration in which both members 2 and 3 are provided with tapered surfaces 10a, 10b, 11a and 11b, respectively, and are provided with a stepped portion 12.

As shown in FIG. 5 (b), which is an enlarged view, the stepped portion 12 has a stepped surface 12b perpendicular to the axis on the side of the shaft member 2, and The side of the stepped portion 12a is formed as a stepped portion surface 12a having a 45-degree inclination, and when it is fitted to each other and pressed in the axial direction, the contact portion 17 is deformed or collapsed by a slight pressure to reach an assembly dimension. Pressing up to this will secure the target dimensions.

FIG. 6 shows a preferred embodiment for adjusting the overall length. The formation of the tapered surfaces 10 and 11 of the fitting surfaces is the same as that of the above-described embodiment, but is different from that of the above-described embodiment. The difference is that the projections 14 and 15 are provided on the opposing surfaces of the members 2 and 3.

When the projection 14 of the outer member 3 presses the inclined surface of the projection 15 of the shaft member 2, it deforms or collapses with a slight pressure until it reaches the assembly size, and cracks occur in both members 2, 3. The desired dimensions can be secured without any problems.

FIGS. 7 to 9 show an embodiment in which a concave groove 7a, a convex line 6 and a concave line 7b for forming a gap 8b are formed on the fitting surface.

The cylindrical fitting surfaces of the shaft member 2 and the outer member 3 have tapered surfaces 10 and 11 as in the above-described embodiment.
Is formed.

As shown in FIG. 7 which shows a cross-sectional view of the cylindrical portion 4, the shaft member 2 is formed with concave lines 7a and 7b, and the outer member 3 is formed with a convex line 6; The details of assembling the ridge 6 are performed as shown in FIG. 9, and the height of the ridge 6 is 1.5 mm.
And the gap with the bottom of the concave strip 7 is 0.3 mm.

The width of one of the ridges 6 (upper side in the figure) is widened so that the phase of the two members 2 and 3 can be determined. The gap between the engaging portion 9 of the concave ridge 7a and the convex ridge 6 is 5 μm.

Further, as shown in FIG. 8, the ridges 6 and the concave ridges 7a have a fitting surface formed in a tapered shape, and are dimensioned so as to be fitted by a loose fit.

Also, two concave stripes 7b which do not mesh with the convex stripes 6
Is 0.3 mm.

With such a configuration, since the concave ridges 7a and the convex ridges 6 are tapered, they can be easily fitted.

For the assembly assembled as shown in FIG. 7 and the assembly assembled as shown in FIG. 1, the joint breaking load when rotating torque was applied between the members 2 and 3 was measured. 7, the one in FIG. 7 is concave streak 7a.
1 and the ridge 6 are engaged, the joint-breaking load is about four times higher than that of FIG.

In addition, in the case where the gaps 8a and 8b are formed as shown in FIG. 7 and the sample in which the gaps 8a and 8b are not provided in FIG. However, about 5% occurs in the latter case, and the maximum value of roundness is 3% in the latter case compared to the former.
The gaps 8a and 8b increase the quenching distortion by about 0%.

FIGS. 10 to 11 show an embodiment in which two outer members 3 are provided as 3a and 3b.

FIG. 10 shows tapered surfaces 10 and 11.
Are formed flush with each other, and the dimensions are set so that the fitting between the shaft member 2 and the outer member 3 is tightly fitted.

Further, a projection 15 can be formed at the end face contact portion as required.

On the other hand, FIG. 11 shows an example in which a stepped portion 12 is provided on the tapered surfaces 10 and 11 as in FIG. 5 described above.

However, in these cases, it is necessary to increase the wall thickness of the cylindrical portion, and there is a disadvantage that the parts become heavy.
It is preferable that the outer members 3a and 3b have a shape of only the collar portion.

As described above, according to the above-described embodiment, the fitting surface between the two members, the shaft member 2 and the outer member 3, is
Since the composite sintered parts are manufactured as 0 and 11, a gap is provided between the two members 2 and 3 at the entrance of the fitting, so that they can be easily inserted into each other.

The shaft surface of the shaft member compact 2 ′ has a small-diameter tapered surface on the cylindrical portion end face side, and the bearing surface of the outer member compact 3 ′ has a large-diameter tapered surface on the cylindrical portion end surface side. In addition, since each taper ratio is set to 10/100 to 60/100 and the outer member 3 is formed to have a smaller taper ratio than the shaft member 2, the outer member 3 is fitted when the two compacts 2 ', 3' are fitted. 3 can be improved.

Further, the tapered surfaces 10 and 11 are
2, the inclination of the stepped portion 12 with respect to the axis is formed differently between the shaft member 2 and the outer member 3 and pressed in the axial direction in a state where the two are fitted. After the root or corner portion abuts on the other stepped portion surface 12a,
If the roots or corners are deformed or collapsed by a weak pressure and pressed down to the full length of the assembly, the desired dimensions can be secured without causing cracks in the members 2 and 3.

When the projections 14 and 15 are provided on the opposite end surfaces of both members 2 and 3 and pressed in the axial direction, the projections 14 and 15 are deformed or collapsed by a weak pressure.
If the members are pressed until they reach the total length of the assembly, the target dimensions can be secured without causing cracks in the members 2 and 3.

A gap 8a between the top of the ridge 6 of one member and the bottom surface of the concave ridge 7a meshing with the ridge 6, and a gap formed between the other concave ridge 7b and the cylindrical surface of the one member. 8b, the arrangement of which is formed at a substantially equal distance around the circumference of the fitting surface, thereby absorbing the distortion deformation of the two members 2 and 3 in the vicinity, improving the roundness of the component and improving the roundness. In the case where the members are provided, the concentration of the quenching stress is eased by the gaps 8a and 8b, so that the members 2 and 3 are hardly cracked.

Furthermore, when the width direction of the fitting ridge 7a and the ridge 6 to be fitted is formed in a tapered shape, there is a gap between them at the entrance of the fitting, so that the insertion becomes easy.

[0072]

As described above, according to the manufacturing method of the present invention, since the fitting surfaces of the shaft member and the outer member are formed in a tapered shape when the composite sintered part is manufactured, the assembling operation can be performed efficiently. be able to.

Further, since the stepped portions of the tapered surface are in line contact with each other or a projection is provided at the end face opposing portion, the overall dimensional accuracy of the assembling is improved.

Further, since concave and convex ridges are provided on the fitting surface between the shaft member and the outer member, a clearance for strain stress is provided at the engaging portion of each other. The target strength is high, the dimensional accuracy is good, and furthermore, the cracking hardly occurs. Therefore, when the manufacturing method according to the present invention is applied to the manufacture of a mechanical element such as a double-flanged sprocket used for an automobile or the like, a high-quality part can be obtained, and various other sintered parts having similar shapes can be obtained. The use can be expanded.

[Brief description of the drawings]

FIG. 1 is an explanatory cross-sectional view of a sintered component to which the present invention is applied.

FIG. 2 is a cross-sectional view schematically showing a state after extraction of the outer member after compaction.

FIG. 3 is an explanatory sectional view showing a fitted state of a green compact.

FIG. 4 is an explanatory cross-sectional view when a taper ratio of an outer member is reduced.

FIG. 5 is an explanatory cross-sectional view when a stepped portion is provided on a tapered surface.

FIG. 6 is an enlarged sectional view of a main part when a projection is provided on an end face.

FIG. 7 is an explanatory cross-sectional view showing a fitted state when a ridge engagement portion is provided.

FIG. 8 is an enlarged sectional view of a main part showing an example of fitting of a ridge and a ridge.

FIG. 9 is an enlarged cross-sectional view of a main part, illustrating an engagement state of a ridge and a ridge.

FIG. 10 is an explanatory sectional view showing an embodiment having two outer members.

FIG. 11 is an explanatory sectional view showing another embodiment in which two outer members are provided.

FIG. 12 is an explanatory sectional view showing an example of a conventional sintered component.

[Explanation of symbols]

 2 Shaft Member 3 Outer Member 5a, 5b Collar 6 Convex 7a, 7b Concave 8a, 8b Clearance 10, 11 Tapered Surface 12 Stepped Part 14, 15 Projection

──────────────────────────────────────────────────続 き Continuing on the front page (72) Akira Oki, Nissan Motor Co., Ltd., 2 Takaracho, Kanagawa-ku, Yokohama, Kanagawa Prefecture (72) Yuji Kishi, 2 Takaracho, Kanagawa-ku, Yokohama, Kanagawa, Nissan Motor Co., Ltd. (72) Inventor Hiromasa Imazato 2 Takaracho, Kanagawa-ku, Yokohama-shi, Kanagawa Nissan Motor Co., Ltd. (56) References JP-A-48-8639 (JP, A) (58) Fields investigated (Int. ⁷ , DB name) B22F 7/06

Claims (5)

(57) [Claims] 1. Production of a composite sintered body in which a green compact shaft member and a green compact outer member fitted to the shaft member are sintered and integrated with each other in a fitted state. In the above method, the shaft surface of the shaft member is formed as a small-diameter tapered surface on the front end side to be fitted, and the bearing surface of the outer member is formed as a large-diameter tapered surface on the mating entrance side, and each taper ratio is 10. / 100 to 60/100, a method for producing a composite sintered part. 2. A green compact shaft member having a flange at one end of a cylindrical portion and a green compact outer member having a flange at one end of the cylindrical portion are sintered in a mutually fitted state. In the method for manufacturing a composite sintered body, the end surface of the cylindrical member is formed as a small-diameter tapered surface, and the end surface of the outer member is formed of a large-diameter tapered surface on the end surface of the cylindrical portion. And each taper ratio is 10 /
A method for manufacturing a composite sintered part, wherein the outer member is formed to have a taper ratio smaller than that of the shaft member. 3. The tapered surfaces of the shaft member and the outer member each have a stepped portion and are formed as two tapered surfaces, and the inclination of the stepped portion with respect to the axis differs between the shaft member and the outer member. formed and pressed push axially fitted both members, optionally abutment deformation, collapse, object
3. The method for manufacturing a composite sintered part according to claim 2, wherein dimensions are secured . 4. When the shaft member and the outer member are fitted, at least one of the flange portion of the shaft member and the end face of the outer member, which are opposed to each other, are provided with annular or annularly continuous projections at regular intervals. provided both members to form and pressed push axially fitted both members, optionally, the protrusions deform, collapse
4. The method for manufacturing a composite sintered part according to claim 2 , wherein a target dimension is secured . 5. On the other hand in the axial direction of the fitting surface of the member other
One or more ridges protruding toward the member are formed, and the ridges are formed in a trapezoidal shape having a small width at the end face side of the cylindrical portion and a large width at the other end side, and a cylindrical fitting surface of the other member. In addition to forming a concave strip having a shape fitted in the width direction of the convex strip and separated in the height direction along the axial direction at a position corresponding to the convex strip, an additional concave strip is formed on the circumference. 5. The method for producing a composite sintered component according to claim 2, wherein the composite sintered component is formed at intervals.