JPH0442442B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field of the Invention) The present invention relates to a method for producing a sintered part by efficiently sintering a plate-shaped powder compact with high quality.

(Technical Background of the Invention) Conventionally, the following method has been known as a method for manufacturing a relatively thin plate-shaped sintered part such as a valve plate for a refrigerator.

(1) As shown in FIG. 1a, a method in which a plurality of powder compacts 2 are stacked vertically on a tray 1 made of iron, molybdenum, ceramics, etc. and sintered.

(2) As shown in FIG. 1b, a method in which a plurality of powder compacts 2 are arranged on a tray 1, stacked in multiple stages, and sintered.

(3) As shown in Fig. 1c, a plurality of powder compacts 2 are placed upright on a tray 1, closely aligned in the thickness direction, and both ends are sandwiched between pressers 3 made of iron or other heat-resistant material. How to sinter with.

(Problems with the background art) However, in the above conventional method, (1)
In this method, the compacted compacts 2 on the opposite side of the tray 1 are directly exposed to the flame of the burner in the furnace, resulting in poor flatness after sintering. However, method (2) is affected by the flatness of the tray, requires a large number of trays, and, like method (1), the height of the furnace mouth is limited. There are restrictions depending on the size.

In addition, in method (3), although there is no restriction due to the height of the furnace mouth, the parts of the compacted compact 2 at both ends that have come off the presser material 3 are directly exposed to the burner flame and warp, and the parts at both ends The inner few sheets had the disadvantage that they became unusable due to poor flatness and that the parts would stick together during sintering.

(Objective of the Invention) The present invention has been made to eliminate such conventional drawbacks, and efficiently sinteres a plate-shaped powder compact with high quality. The present invention aims to provide a method for manufacturing sintered parts.

(Summary of the Invention) The present invention provides that when a plurality of plate-shaped powder compacts are stood upright and closely aligned in the thickness direction, one or two or more of the powder compacts are It is characterized by sintering the powder compacts by sandwiching and arranging them in different orientations, and sandwiching both ends of the powder compacts between pressing materials with heat-resistant plates having a size that covers the compacted powder compacts.

Molybdenum or ceramics can be used as the heat-resistant plate.

(Example of the invention) Examples of the present invention will be described below.

Example First, 98 parts by weight of iron powder was mixed with 1 part by weight of graphite powder and 1 part by weight of lithium stearate as lubricating oil, and compression molded using a mold at a pressure of about 5 tons/cm ² to form a 60 mm × 40 mm × 2.5mm flat powder compact 4
I got it.

The warpage of the powder compact 4 at this time (height of warpage from the flat surface when placed on a flat surface) is 0.04 to 0.06
It was warm in mm.

Next, as shown in FIG. 2, about 150 compacted compacts 4 are stacked upright in the thickness direction while changing the orientation of every 5 to 10 compacts, and both ends are
A 65 mm x 45 mm x 2.5 mm aluminum ceramic plate 5 is sandwiched between 45 mm x 45 mm x 15 mm iron pressers 6 and placed directly on the furnace tray 7 with the edge (60 mm x 2.5 mm surface) facing down. This was then charged into a mesh belt type sintering furnace and sintered at a temperature of 1100°C for 30 minutes.

The warpage of both end pieces after sintering was 0.05 to 0.08 mm. Moreover, the work of disassembling the material after sintering was easy. This is thought to be due to the small gaps created by parts whose orientation has changed to prevent them from sticking during sintering.

On the other hand, when the ceramic plate 5 was not used and the product was sintered directly between the pressers, the warpage of the sintered product at both ends was 0.15 to 0.30 mm.

(Effects of the invention) As explained above, conventionally, when the products were aligned in the same direction, the products tended to stick.
According to the method of the present invention, the product after sintering is less likely to stick, the flatness of both end products after sintering is significantly improved, and the workability is improved, such as reducing the warping process.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing the state of sintering of a plate-shaped powder compact by the conventional method, and FIG. 2 is a perspective view showing the sintering state of the plate-shaped powder compact by the method of the present invention. 1, 7...Tray, 2, 4...Powder compact,
3, 6...pressing material, 5...ceramics board.

Claims (1)

[Scope of Claims] 1. When a plurality of plate-shaped powder compacts are stood upright and closely aligned in the thickness direction, the orientation of one or two or more of the powder compacts for every several powder compacts is determined. A method for manufacturing a sintered part, which comprises sintering the powder compacts by aligning them while sandwiching them, and sandwiching both ends of the powder compacts between pressers with heat-resistant plates having a size that covers the compacted powder compacts. 2. The method for manufacturing a sintered part according to claim 1, wherein the direction of the powder compact is changed by one or two or more powder compacts every 5 to 10 compacts.