CS255355B1 - Powdered porous metal blank for hot forming parts - Google Patents

Abstract

During continuous induction heating of porous powder semi-finished products, produced by powder metallurgy processes and intended for the production of full-density parts, e.g. by forging or extrusion, their sintering occurs at temperatures above about 850 to 900 °C. The exclusion of such sintering of semi-finished products during their induction heating up to temperatures up to 1,300 °C is ensured by a porous powder semi-finished product, which has protrusions in the form of a full circle or an annulus formed in the central part on both faces during pressing, which can be advantageously interrupted.

Description

In the continuous induction heating of powdered porous semi-finished products produced by powder metallurgy processes and intended for the production of full density components e.g. by forging or by extrusion, dDC is sintered at temperatures above about 850 to 900 ° C. The elimination of such sintering of the blanks in their induction heating up to temperatures of up to 1300 ° C is ensured by a porous, porous blanks which, on both press faces, have solid or protruding protrusions in the center part which can preferably be interrupted.

BACKGROUND OF THE INVENTION The present invention relates to the shape of a powder-like metal blank for the manufacture of powdered parts by molding from. heat.

Heating of porous metal powders, preforms. processing them into parts by thermoforming, e.g. by forging or by extrusion, to date it has been carried out in two main ways. On the one hand it is heating in continuous or rotary resistance heated furnaces, on the other hand it is induction heating, always in a protective atmosphere. Heating in resistance-heated furnaces takes place relatively slowly and the heated blanks are stored in a box or directly on the furnace strip next to each other, or are individually blasted through the furnace to separate devices so that the blanks do not touch each other to avoid possible sintering. Such furnaces are bulky and expensive. Induction heating compared to resistance heating is fast, energy, investment and space less demanding and can achieve high hourly output. In order to achieve these high induction heating capacities, it is necessary to carry out the heating in continuous inductors in which the semi-finished products are heated in successive steps and are moved one piece at a time. As a result, the blanks must touch each other with their cells.

A disadvantage of the preforms used hitherto is that the intensification of the heat induced by the induction first only in the top layers of the preform and the pressure when pushed through the inductor will sinter, bond at temperatures above about 850-900 ° C. In order to achieve full density of powder forgings, which is an essential prerequisite for achieving high component performance and less forging forces, it is necessary to form such components at temperatures between 1050 and 1150 C. Because of this, the sintered powdered porous metal blanks are continuously inductive. heat only to the lower temperatures indicated or individually at low power. Semi-finished products with known three projections < 6 2 mm, heights of a few tenths of a millimeter on only one face, are also sintered if they have a heavier weight, as the projections are compressed when shifting the larger column through the inductor. This is especially evident in the vertical inductor, where the entire weight of the column is acting. Also, it is necessary to orient the blanks individually manually before being fed into the inductor, which reduces labor productivity.

Said shortcomings of the powdered porous metal blanks for the production of hot-forming components are overcome by the powdered metal blanks, which is based on the fact that they have at least one protrusion of 0.2 to 1 mm in height on both faces in the central part. annulus.

The blank may advantageously have two concentric protrusions of different widths, the protrusions may be interrupted and may be offset from one another.

The advantage of such a powdered porous metal blank with the projections on both faces is that it substantially eliminates their caking, sticking at induction heating to a temperature of up to 1300 ° C with intermittent displacement in horizontal and vertical inductors without affecting the size and weight of the blank. This makes it possible to quickly and efficiently heat induction powder blanks with or without an internal bore to produce components e.g. by forging or by extrusion. The above-described semi-finished products achieve high and trouble-free performance over the entire production cycle without the need for their individual orientation before heating. A further advantage of these blanks is that, with intermittent protrusions, the protective atmosphere flowing in the inductor more perfectly washes the outer and inner surfaces of the column formed from the heated blanks with an internal bore in the continuous inductor due to a reduction in temperature difference. These advantages of the powdered semi-finished products substantially extend the field of application of the advantageous induction heating for the production of even high-demand parts by thermoforming and hence the economically advantageous powder metallurgy technology.

Image description

In the drawing, in sectional view A-A, it is indicated: 1 - a powdered porous metal product, 2 - a projection of fig. 1. a blank with a hole with an annular protrusion, FIG. 2 shows a solid blank with a protrusion of a solid circle, FIG. 3 shows a solid blank with an annular protrusion, FIG. 4 shows a blank with a hole with two annular protrusions, FIG. 5 shows a blank with a hole with four protrusions in the form of an intermittent ring, FIG. 6 shows a solid blank with two protrusions in the shape of an interrupted annulus, FIG. 7 shows a blank with a hole with projections facing each other in the shape of two interrupted annulus.

From the pre-alloyed steel powder, cold pressed semi-finished products 1, with a density of 6.3 g, were pressed. cm ^-3 , outer diameter 0 71 mm, inner diameter 0 60 mm, base height 20 mm and weight 145 g with protrusions 2 on both faces according to fig. 1 and an inner diameter of 0 60 mm, an outer diameter of 0 66 mm and a height of 0.8 mm. The powdered semi-finished products 1 thus formed after conventional sintering and cooling and lubricated with graphite emulsion, rods in 255355 are heated by heat in a horizontal inductor. The blanks 1 are arranged in the inductor so that they touch the formed protrusions 2, and so the entire column of blanks, which consisted of 45 blanks, was moved in the chosen cycle for 6 seconds through the indole with the supply of another blanks. The blanks when they are removed from the inductor have a temperature of 1150 ° C without being disturbed. This allowed continuous continuous automatic heating and feed to the forging tool. The thus heated blanks were then forged in a closed tool for forging the roller bearing ring. Semi-finished products 1 of the same characteristics, but with the same cells without protrusions 2, at 1100 ° C were completely sintered, making production impossible. Induction heating of the blank 1 without projections was possible without sintering only up to a temperature of 930 ° C, which is a low temperature for forging heavy duty machine parts of pre-alloyed powders. Advantageously, the porous porous metal blank 1 with the protrusions 2 can be inductively heated to temperatures up to 1300 degrees Celsius, both in the pre-sintered state and in the pre-sintered state.

Powdered metal porous blanks 1 with protrusions 1 can advantageously be used in the manufacture of machine parts by forging, such as e.g. roller bearing components, gears and other components for which the blank 1 can be inductively heated from a shape point of view. At the same time, the field of application of the induction heating of powdered blank products for thermoforming is widened.

Claims (6)

255358 ductally heated in the liner inductor. The blanks 1 hurt in the inductor by contacting the formed bosses 2, and thus the entire half blanks, which consisted of 45 blanks, were connected to the inductors for 6 seconds by feeding the next blanks. Products to be extruded from the low temperature inductor of 1150 ° C without slagging. This allowed for continuous continuous automatic heating and feed into the tool. Such heated semi-finished products were then forged in a closed tool on a forged bearing ring ring. Semi-finished products 1 of the same characteristics, but with the same Cells 2, at a temperature of 1100 ° C, were completely slagged, making production impossible. Induction heating of the protrusion-free blank 1 was only possible without sintering up to a temperature of 930 ° C, which is for forging high-performance machine parts from pre-alloyed powder-free temperature. Preferably, the porous powdered metal powder 1 with protrusions 2 can be inductively heated to temperatures up to 1300 degrees Celsius, both in the non-sintered state and in the pre-sintered state. The metal powder porous workpieces 1 with the protrusions 2 can be advantageously used in the manufacture of machine parts by forging, eg. components of rolling bearings, gears and other components for which the product 1 can be inductively heated from a form-fitting view. This simultaneously extends the field of application of induction heating of powder semifinished products for thermoforming. OBJECT CLAIMS 1. Powdered, porous, semi-finished metal powder for the production of thermoformed parts, characterized in that on both cells of the middle part, a height of 0.2 to 1 mm is formed on at least one projection (2). 2. The porous metal powder according to claim 1, characterized in that the projections (2) formed have a full circle shape. 3. A powder-like porous blank according to claim 1, characterized in that the projections (2) formed have an annular shape. vynalezu 4. Powdered porous metal semi-finished product according to claim 1, characterized in that two protrusions (2) of latitude are formed. 5. The porous powdered metal blank according to items 1, 2, 3 and 4, wherein the protrusion (2) is interrupted on at least one face. 6. Powdered porous metal semi-finished product according to items 1, 4 and 5, characterized in that the projections (2) formed as two interrupted arcs are offset against each other. 2 sheets of drawings