RU2215629C2 - Method for joining porous metallic or metal-ceramic materials - Google Patents

Abstract

FIELD: welding metals and alloys, for example making cartridge type filtering members, other branches of technology needed non-detachable joints of porous metallic and metal-ceramic materials. SUBSTANCE: method comprises steps of preliminarily focusing beam to spot with diameter consisting (0.2 - 0.4)δ on surface of joined parts; opening joined edges of parts by value exceeding by 10 - 15 % diameter of heating spot; placing in root portion of joint insert made of compact metallic material and having height equal to (1.5 -2.0)δ and width equal to (1.2 -1.6)δ and embedded into porous material of part by depth (0.15 -0.35)δ, where δ - thickness of porous material; then heating butt by means of beam with energy per length unit providing fusion of insert material by value consisting 0.7 -0.8 of its height. Method provides lowered quantity from 30% to 4 % of rejected joints due to prevention of non-sealed places in welding zone. EFFECT: enhanced quality of welded joints. 3 dwg, 1 tbl

Description

 The invention relates to the field of welding of metals and alloys and can be used, for example, in the manufacture of filter elements of cartridge type, as well as in other areas of technology, where it becomes necessary to obtain a permanent tight connection from porous metallic or cermet materials.

 The most common method for joining parts of porous metal materials is vacuum heating using an electron beam (see Lisovsky A.F., Sirota K.I. Investigation of the process of joining sintered alloys of the tungsten carbide-nickel system. // Welding Production - 1980. - 2, p. 11-12). When heated in a vacuum, the gap is filled with a eutectic melt and, when cooled, a uniform metal structure is formed in the joint zone. However, when using this method for connecting parts of filter elements, uniform penetration of the material into the channels of the porous material is not ensured, which entails an unstable quality of the compounds.

 Closest to the claimed is a method of connecting a compact metallic and porous metallic or cermet materials by heating with an electron beam, which consists in assembling the connection of these materials, inducing an electron beam of a certain power on the joint of materials and their subsequent heating when the parts rotate at a speed of 25-30 m / h (see Afonin M.M., Ovchinnikov V.V., Magnitov BC Electron beam welding of cartridge-type filter elements. // In Sat. Progressive welding and soldering processes in a machine swarming -. M .: Russian House of Knowledge -. 1997, pp 67-69).

 The disadvantage of this method is the low quality of the connection of parts made of porous metal materials due to changes in the density of the material during heating and melting (an underestimation of the seam is formed), as well as unregulated penetration of the melt into the capillary channels of the porous material. Due to these reasons, the connection is often leaky, which is unacceptable, for example, in the manufacture of cartridge filter elements.

 The technical result of the invention is to improve the quality and tightness of the joints in parts of porous metal materials.

 The result is achieved in that in the method of joining porous metallic or cermet materials by heating with an electron beam, the beam is pre-focused into a spot with a diameter of (0.2-0.4) δ on the surface of the parts to be joined, the joined edges of the parts are moved apart by 10-15% more the diameter of the heating spot, in the root part of the joint an insert is made of compact metal material with a height of (1.5-2.0) δ and a width of (1.2-1.6) δ with a recess in the porous material of the part at (0.15-0 , 35) δ, where δ is the thickness of the porous material, after which the joint is heated by a beam with linear energy, providing the penetration of the insert material at 0.7-0.8 of its height.

 In FIG. 1 is a diagram of an assembly of a weld joint; figure 2 presents a diagram of the guidance and focusing of the electron beam when welding the butt joint of porous metal materials; in FIG. 3 shows the formation of the joint when welding workpieces of porous metal materials.

 The method is as follows.

 The joint of a porous metal material is assembled end-to-end. The electron beam is directed to the joint of the parts to be joined and focused into a spot with a diameter of (0.2-0.4) δ, where δ is the thickness of the porous material. When a beam is focused into a spot with a diameter of less than 0.2δ, intense evaporation of the porous material occurs with its vapor settling on the surface of the part, resulting in a loss of its filtering properties (bandwidth) due to clogging of the capillary channels. When focusing the beam into a spot with a diameter of more than 0.4δ, the penetrating ability of the beam is reduced, which causes the expansion of the seam and an increase in the beam energy needed to melt the insert to a predetermined depth.

 After focusing the beam before welding, the edges of parts 1 and 2 of a porous metal material are moved apart by a width exceeding the diameter of the heating spot by 10-15%. If the edges of the parts are extended by less than 10% the diameter of the heating spot, intense melting of the edges of the parts occurs, leading to the formation of an underestimation of the seam on the front side of the joint and the occurrence of microcracks along the boundary of the cast zone and the porous metal material. When the edges of the parts are extended by more than 15% more than the diameter of the heating spot, the melt penetrates into the channels of the porous material in the upper part of the welded joint due to insufficient heating of the material in this zone.

 An insert 3 of compact metal material with a height of (1.5-2.0) δ and a width of (1.2-1.6) δ with a recess in the porous material by (0.15-0.35) δ is installed in the root part of the compound . When the insertion height is less than 1.5δ during welding, there is a lack of melt to fill the capillary channels in the porous material. In this case, an underestimation of the seam is formed and the strength of the welded joint decreases. When using an insert with a height of more than 2.0δ, the flow area of the cartridge-type filter element is reduced and the consumption of compact metal material is increased.

 In the case of using an insert with a width of less than 1.2δ with fluctuations in the heating mode and the position of the beam relative to the axis of the joint, a shift in the zone of melting of the material to one of the edges is observed. This leads to a violation of the formation of the connection and loss of tightness of the filter element. When the insert width is more than 1.6δ, on the one hand, the consumption of compact material increases, and on the other hand, the filter surface area decreases.

 The depth of penetration of the insert in parts of a porous metal material is greatly influenced by the formation of the compound. When the insert is deepened into the porous material by less than 0.20δ, the melt energy of the electron beam must be increased to ensure the melt rises to the entire thickness of the porous metal material being welded and penetrates uniformly into the capillaries. This causes an intensification of the evaporation of the insert material, followed by vapor deposition on the surface of the parts of the porous metal material. Vapor deposition leads to the closure of the capillary channels through which the liquid or gas is filtered and, therefore, the filter capacity will be reduced.

 When the insert is deepened into the porous material by more than 0.50δ, the working cross-sectional area of the seam on the filter element decreases. This reduces the load that the filter can withstand, i.e. the value of the internal working pressure at which the filter can be operated is reduced.

 Welding is carried out with the linear energy of the beam, providing the penetration of the compact metal material of the insert at 0.7-0.8 of its height. When the insert is fused to a depth of less than 0.7 of its height, the volume of liquid metal penetrating into the capillary channels of the porous material decreases. This entails uneven filling of the capillary channels in the joint zone and a decrease in its strength. When the insert is penetrated to a depth of more than 0.8 of its height, a periodic opening of the vapor-gas channel from the root side of the joint is observed. This phenomenon causes the weld to sag in the joint zone, violate the filling of the capillary channels of the porous material with liquid metal and deposit compact material on the inner surface of the blanks of the filter element from the porous material.

 An example implementation of the method.

 Two glasses were made of pressed sintered powder of steel grade ПХ18Н15 with a diameter of 52 mm. The wall thickness of the glass was 3 mm. Connection - butt. Welding was performed on an ELU-20MK installation equipped with a multi-position manipulator and an ELA-60/60 power unit. An insert made of a compact metal material of grade 12X18H10T was placed in the root part of the compound. Insert parameters, heating mode and their influence on the quality of the connection are shown in the table.

 Compared with the known, the inventive method provides a high quality connection of blanks from a porous metal material in the manufacture of cartridge filter elements and a reduction in the percentage of defective products from 30 to 4% by preventing the formation of leaks in the fusion zone on the porous material. In addition, the inventive method provides an opportunity for the manufacture of filter elements of cartridge type increased throughput without the manufacture of new equipment for pressing and sintering powder.

Claims (1)

 A method of joining porous metallic or cermet materials by heating with an electron beam, in which a melt insert is installed between the surfaces to be welded to be joined, characterized in that the beam is pre-focused into a spot with a diameter of (0.2-0.4) δ on the surface of the parts to be joined, abutting edges parts are pushed apart by 10-15% more than the diameter of the heating spot, an insert of compact metal material with a height of (1.5-2.0) δ and a width of (1.2-1.6) δ with angle ubleniem in detail on a porous material (0,15-0,35) δ, where δ - thickness of the porous material, after which the heating is carried out with a joint heat input beam providing material penetration insertion 0.7-0.8 of its height.

Images