The invention belongs to the technical field of cemented carbide rod extrusion molding, and specifically relates to an extrusion method for producing cemented carbide rods.
Background technique:
When using the extrusion method to manufacture circular cross-sections, special-shaped cross-sections and perforated cemented carbide profiles with a large aspect ratio, most of them need to be wet milled, mixed with slurry, vacuum dried, sieved into mixed powder, and then mixed Forming agent is formed by extrusion molding, dry air drying, processing and drying, pre-burning degreasing, cut to length, and sintering. It not only has more process restrictions, but also has a long production cycle, which seriously affects production efficiency. Compression molding cannot meet the requirements of each process in the production process, and even contradicts each other. For example, the mixed slurry is prepared by vacuum drying and sieving machine, which not only has long working hours and high energy consumption, but also for ultra-fine grains. For alloy powder, it is easy to cause burning and out of control of oxygen content; in addition, for uniformityGround mixing powder is mixed with forming agent. The rubber and cellulose forming agent process uses polymer glue which is very viscous and can only be carried out in a small capacity Sigma mixer. Each time the mixture is added 25Kg, which seriously affects the processing The efficiency of the blending process will also be affected by human factors, which will affect the quality of the processing; at the same time, the use of shade drying, air drying, and heating and drying under normal pressure takes a long time, generally more than 30 days, which seriously affects the processing efficiency. Moreover, after drying, the extruded rod cannot be directly entered into the cut-to-length process. Pre-burning and degreasing must be carried out. This not only greatly increases the production cost, but the dewaxed extruded rod is easily oxidized and heated after being out of the furnace, causing the sintered rod to be damaged. The oxygen content fluctuates. It can be seen from the above that the traditional extrusion method is limited to a certain extent, and it is difficult to meet the market demand.
Technical realization elements:
The purpose of the present invention is to provide an extrusion method for producing cemented carbide bars, aiming to simplify the processing flow and improve the processing efficiency.
The technical solution to achieve the purpose of the present invention is an extrusion method for producing cemented carbide bars, which includes wet grinding of raw materials, mixing slurry and spray drying, mixing powder and mixing forming agent, extrusion molding, vacuum drying, fixed Ruler cutting and integrated sintering, adding paraffin, cellulose and active agent during wet grinding of raw materials, adding molding binder during extrusion molding.
The forming binder includes 0 based on the weight of the mixture.4-1% ethyl cellulose, 0-0.3% stearic acid, 0-0.8% paraffin, 0-0.3% vinyl wax, 0-0.3% random polypropylene and 3-7% compound solvent.
The compound solvent is an organic liquid with a boiling point of 150-175C.
Or the molding binder includes 0-1% polyethylene, 0-1% random polypropylene, 0-0% based on the weight of the mixture.5% ethylene-vinyl acetate copolymer, 0-0.5% rosin pentaerythritol ester, 0-1.5% paraffin, 0.1% stearic acid, 0.1% dibutyl phthalate and 3-7% decane.
When mixing the molding agent, use a 200L or 300L volume stirring mixer and circulate heating and cooling during mixing..
The present invention has positive effects: the process of the present invention is simple, compared with the ten processes of the traditional technology, three processes are reduced, which is beneficial to save man-hours and improve the processing efficiency to a certain extent. At the same time, paraffin wax is added during wet grinding. Cellulose and active agent not only ensure the granulation effect of the mixture during spray drying, but also increase the direct yield of the powder. The molding binder is added in the extrusion molding, which can make the extrusion rod break and implement rapid volatilization. The oil becomes feasible, and it can also ensure rapid drying without cracking, which is beneficial to improve processing efficiency, and can be directly cut to length after extrusion molding, thereby reducing the pre-burning and degreasing process and ensuring the oxygen content in the sintered bar. Stability, good stability and applicability.
Description of the drawings
In order to make the content of the present invention easier to be understood clearly, the following further describes the present invention in detail based on specific embodiments in conjunction with the accompanying drawings, in which:
Figure 1 is a schematic diagram of the process flow of the present invention.
Detailed ways
(Example 1)
Figure 1 shows a specific embodiment of the present invention, in which Figure 1 is a schematic diagram of the process flow of the present invention.
See Figure 1, an extrusion method for producing cemented carbide bars, including wet grinding of raw materials, mixing slurry and spray drying, mixing powder and mixing forming agents, extrusion molding, vacuum drying, cut to length and integration Chemical sintering, adding paraffin, cellulose and active agent during wet grinding of raw materials, adding molding binder during extrusion molding.
The forming binder includes 0 based on the weight of the mixture.4-1% ethyl cellulose, 0-0.3% stearic acid, 0-0.8% paraffin, 0-0.3% vinyl wax, 0-0.3% random polypropylene and 3-7% compound solvent.
The compound solvent is an organic liquid with a boiling point of 150-175C.The solvent component uses an organic liquid with a boiling point of 150-175C to replace or partially replace high boiling point (200C) organic solvents (such as tetralin, dodecane, etc.).This not only facilitates the mixing of the forming agent, but also makes it feasible to implement relatively fast volatilization and deoiling of the extruded bar stock.The volatilization and deoiling of extruded bar stock under high vacuum and low temperature (20-50) is the key to ensure its rapid drying without crack.
Or the molding binder includes 0-1% polyethylene, 0-1% random polypropylene, 0-0% based on the weight of the mixture.5% ethylene-vinyl acetate copolymer, 0-0.5% rosin pentaerythritol ester, 0-1.5% paraffin, 0.1% stearic acid, 0.1% dibutyl phthalate and 3-7% decane.
Different from the paraffin-based molding agent process in the prior art, the strength and toughness of the extruded rod blank after drying in the present invention depends on the residual polymer organic matter in the rod blank (such as cellulose, polyethylene, ethylene-vinyl acetate copolymer, no Polypropylene), etc..In addition, the extruded bar stock contains less wax (1%), which makes it feasible to directly "cut to length" the extruded bar stock after drying..This can reduce the dewaxing and pre-burning process.After deoiling, the extruded rod has a large number of connected pores (about 30% by volume) due to the volatilization of the oil..This provides the feasibility for rapid debinding integrated pressure sintering.
When mixing the forming agent, use a stirring mixer with a volume of 200L or 300L and circulate heating and cooling during mixing..Use a 200L or 300L volume stirring mixer to mix the rest of the forming agent. Such a mixing equipment can correspond to the quantity of wet grinding batches of a 300L or 600L wet mill..When mixing, heating up-cooling and cooling are repeated cycles. It is necessary to implement cold mixing, freezing and controlling the vacuum degree. The combination of heating-refrigeration cycle and freezing-vacuum is the best extrusion Good practice.
The process of the present invention is simple. Compared with the ten processes of the traditional technology, three processes are reduced. To a certain extent, it is beneficial to save man-hours and improve processing efficiency. At the same time, paraffin, cellulose and active agents are added during wet grinding. To ensure the effect of granulation of the mixture during spray drying, increase the direct yield of powder, add molding binder in the extrusion molding, which can make it feasible to implement rapid volatilization and deoiling of the extrusion rod, and also It can ensure rapid drying without cracking, which is beneficial to improve processing efficiency, and can be directly cut to length after extrusion molding, thereby reducing the pre-firing and degreasing process, ensuring the stability of oxygen content in the sintered bar, and good stability in use And strong applicability.
Obviously, the above-mentioned embodiments of the present invention are merely examples to clearly illustrate the present invention, and are not intended to limit the implementation of the present invention..For those of ordinary skill in the art, other changes or changes in different forms can be made on the basis of the above description.There is no need and cannot give an exhaustive list of all implementation methods.And these obvious changes or changes derived from the essential spirit of the present invention still belong to the protection scope of the present invention.
