JPH0444594Y2 - - Google Patents

Description

[Detailed description of the invention] A. Field of industrial application This invention combines two or more green compacts (compounds in the state before being press-formed and sintered in powder metal sintered parts) and sinters them. The invention relates to sintered parts.

B. Prior art When manufacturing various mechanical parts (automobile parts, office machine parts, etc.) using the powder metallurgy method, when the shape of the parts is complex or when it is necessary to change the properties of the material on a part-by-part basis. For example, it is not possible to mold metal powder in a single press. In that case, the parts are divided into many parts and pressed to produce a powder compact, and the compacts are combined and sintered into the required part shape. To obtain a desired shape by combining green compacts, there are two methods: (a) utilizing the difference in dimensional change during sintering of different types of compacts, and (b) sintering with a metal raw plate sandwiched between the two. There is a method of joining by brazing.

In this case, in order to accurately position a large number of compacted powder bodies, circular irregularities are provided on the end faces of both parts so as to fit into each other.

C. Problems to be solved by the invention However, the positioning of the mating powder compacts in the rotational direction is insufficient only by fitting the recesses and protrusions of the circular cross-sectional shape, and even if the center positioning is correct, the Problems are occurring, such as the distance between the center positions changing due to the springback of the powder, the difference in dimensional changes during sintering, etc. causing the two parts to be misaligned, and gaps to form between the end faces. .

D. Means for solving the problem This invention utilizes this property to solve the above problems, since all changes occur in the radial direction from the center, whether it is springback or dimensional changes during sintering. The purpose is to eliminate positioning problems.

This idea creates circular irregularities (or a combination of shafts and holes) on the combined end face of the green compacts in a sintered part that is a combination of two or more sintered parts, and also creates circular irregularities (or a combination of shafts and holes) on the combined end face of the green compacts. Recesses for center alignment at corresponding positions on the joint surfaces,
In addition to providing a convex portion, a 1.
The combined end face of the two parts has a recess with a depth of 0.5 mm or more, whose cross-sectional shape parallel to the combined face has a straight portion of 0.2 mm or more parallel to the radial direction of the face, and whose both ends are semicircular, The other part in contact with it has a convex part with a circular cross-sectional shape of 0.5 mm or more in height at a position corresponding to the concave part on the other side,
This sintered part is characterized by sintering a combination of these concave portions and convex portions by fitting them together.

The present invention will be explained below using the drawings.

In a sintered part 1 which is a combination of two upper and lower parts as shown in Fig. 1A, the end face of the powder compact 2 of one part has a cylinder for center positioning, as shown in Fig. 1B. A through-hole (recess) 3 is formed, and furthermore, at a radially distant position, the cross-sectional shape parallel to the mating surface has a straight portion of 0.2 mm or more parallel to the radial direction of the surface, and both ends thereof are semicircular. Create a certain recess 4. On the other hand, the combined end faces of the powder compacts 5 of the parts shown in FIG. The circular convex part 6 has a circular cross-sectional shape and a height of 0.5 mm.
The above convex portion 7 is provided. Two compacted powder bodies as described above are made, and the concave and convex portions are fitted together so that the end faces are aligned, and the two bodies are combined and sintered into the shape of the sintered part 1.

In this way, the center position is determined by the fitting of the through hole 3 for center positioning and the convex part 6 of the mating powder compact, and the fitting of the concave part 4 having a parallel straight part and the convex part 7 having a circular cross section. This allows accurate positioning of the two compacts in the rotational direction. Furthermore, even if the mutual center distance changes due to spring back during molding and dimensional changes occur during sintering, these changes are all in the radial direction, so there is no change in the rotational direction. Trouble such as misalignment does not occur and positioning can be performed with high precision. Further, the recess 4 has a straight line section parallel to the radial direction, and even if there is a dimensional change in the radial direction, the fitted convex section 7 can move freely between the straight sections, so that no stress is generated and no deformation occurs.

In addition, the above-mentioned spring back in sintered parts and misalignment due to radial dimensional changes due to sintering will occur at the minimum.
Since the length is 0.2 mm, the straight and parallel portion of the recess 4 must have a length of 0.2 mm. In manufacturing, there are recesses,
Maximum 0.2mm radius (chamfer) on the corners or corners of convex parts
, the depth of the concave part and the height of the convex part must each be 0.5 mm or more. Further, the shape of both ends of the linear portion of the cross-sectional shape of the recess may be arbitrary, but it is rational to make it semicircular in terms of mold manufacturing.

In the above explanation, the case where two powder compacts are combined is explained, but it goes without saying that the present invention can be similarly applied to parts manufactured by combining three or more powder compacts.

In addition, as in this invention, other uneven parts are provided at a position away from the uneven part for positioning the center of the end face, so after combining many compacts and sintering the parts, the joint Additional effects can also be obtained, such as helping to prevent parts from loosening and improving the torque resistance of joints.

Example The parts shown in Figure 2A were manufactured.

First, it has a centrally positioned circular recess 3 as shown in FIG. A compacted powder body 2 having a width of 3.1 mm and a depth of 1.4 mm with semicircular concave portions at both ends was molded. In addition, as shown in FIG.
A powder compact 5 having a circular convex portion 6 for central positioning and a convex portion 7 having a circular cross-sectional shape parallel to the end face with a diameter of 3.0 mmφ and a height of 1.2 mm as shown in FIG. It was made by press molding. The materials of the green compact 2 and the green compact 5 are as follows, and the green compact density of both was 6.9 g/cm ³ .

Powder compact 2 Fe−4Ni−1.5Cu−0.5Mo−0.5C Powder compact 5 Fe−4Ni−3Cu−0.5Mo−0.5C Combine the above two compacts by aligning their end faces.
The product was sintered at 1250°C for 60 minutes in N gas to form part 1 as shown in Figure 2A.

Both parts of this part were accurate in position and rotational position was also accurate.

Furthermore, a conventional combined joint part having only the uneven part for center positioning was manufactured using the same part, and a torque test was conducted with the part of the present invention which had uneven parts for rotational positioning at a distant position in addition to the uneven part for center positioning. compared. Conventional parts loosen (shift in position between the two parts) at 10 kg/m, but the parts of this invention do not loosen even with a torque of 20 kg/m, and the rotational position is accurate and the joints are durable. It was found that torque performance was also improved.

Effects of the invention As explained in detail above, the sintered parts of the present invention have a center-positioning recess on the joint surface of the powder compacts to be joined to each other, even when two or more green compacts with a complex shape are combined. In addition to the convex part, there is a straight part whose cross-sectional shape parallel to the joint surface is parallel to the center line at a position away from the center, and both ends of the straight part have a concave part with a semicircular diameter and a convex part with a circular cross section, and are combined with each other. Compared to conventional sintered parts, even complex parts can be sintered in such a way that not only the mutual planar positional relationship is accurate, but also the position in the rotational direction is accurate. Furthermore, it has the effect of being a component with excellent resistance to loosening and torque at the joint surface.

[Brief explanation of the drawing]

Figure 1A is a perspective view showing an example of parts of the present invention;
Figures B and C are perspective views of the green compact used to manufacture the part shown in Figure 1A. FIG. 2A is a perspective view of a part showing an embodiment of the present invention, and FIGS. 2B and 2C are perspective views showing a powder compact when manufacturing the part of FIG. 2A.
FIG. 3 is a detailed sectional view showing the concave portion of the powder compact of the example, and FIG. 4 is a detailed sectional view showing the convex portion in detail. DESCRIPTION OF SYMBOLS 1... Sintered part, 2, 5... Green compact, 3... Center positioning recess, 4... Recess, 6... Center positioning convex part, 7... Convex part.

Claims (1)

[Scope of utility model registration request] In a sintered part made by combining two or more green compacts and sintering them, recesses and protrusions for center alignment are provided at corresponding positions on the joint surfaces of each green compact, and the green compacts on one side are The joint surface of the body has a straight section parallel to the joint surface at a position away from the center position with a length of 0.2 mm or more parallel to the radial center line of the surface, and both ends of which are semicircular. Yes depth 0.5
A concave portion of mm or more is created, and a convex portion with a circular cross-sectional shape and a height of 0.5 mm or more is provided at the corresponding position on the joint surface of another compact, and the concave and convex portions fit into these compacts. A sintered part characterized by having a joint structure that is combined and sintered in such a manner.