JPS6338248B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention relates to a method for manufacturing an inner liner that is fitted into the inner diameter of a container for a hot extruder. [Prior Art] A container for a hot extruder is composed of an outer cylinder called a tire, an intermediate cylinder called an outer liner, and an inner cylinder called an inner liner made of martensitic hot die steel. Each is shrink-fitted or press-fitted to withstand the high pressure during extrusion. (It is not necessarily a triple cylinder structure of an outer cylinder, an intermediate cylinder, and an inner cylinder, but may be a double cylinder structure of an outer cylinder and an inner cylinder.) [Problems to be solved by the invention] The inner surface of this inner liner When used, they come into contact with the hot material to be extruded and are subjected to high extrusion pressure, so they gradually wear out as the number of extrusions increases. Due to this wear and tear, only the inner liner is replaced with a new one when it is no longer able to withstand normal extrusion work. This inner liner is very expensive and accounts for a large proportion of the extrusion cost, so improving the lifespan of the inner liner is one of the biggest challenges in tool technology. In response to this problem, it has been proposed to repair and reuse the used surface of the worn inner liner by overlaying it with a super heat-resistant alloy. However, these super heat-resistant alloys have low hardness and low wear resistance when overlaid by overlay welding, and cannot sufficiently achieve the purpose of repair. These super heat-resistant alloys undergo aging treatment (approximately 720℃) after welding.
By applying this, high hardness and wear resistance can be achieved. Therefore, in the conventional inner liner made of martensitic hot die steel overlaid with a super heat-resistant alloy, aging effects were expected due to heat conduction from the extruded material during extrusion. However, with this method, even if a super-heat-resistant alloy with excellent high-temperature strength is overlaid, the properties of the super-heat-resistant alloy cannot be fully demonstrated due to its low hardness in the as-welded state. The drawback was that the build-up welded parts would wear out, settle, and plastic flow would occur in the early stages. Therefore, in order to bring out the properties of the overlay welded part, it is necessary to perform an aging treatment after welding, but in the conventional method, the base material is martensitic hot die steel, and the tempering temperature is 600 to 620. Since the base material was softened due to the low temperature of ℃, it was not possible to perform aging treatment. An object of the present invention is to provide an inner liner for a hot extruder that has high wear resistance. [Means for Solving the Problems] As a result of various studies, the present inventor found that (1) a process of solution treatment of the inner liner base material made of austenitic hot die steel; (2) a process of aging the inner liner base material; (3) A step of overlay welding a super heat-resistant alloy to the use surface of the inner liner base material to form two or more overlay layers. (4) Aging the inner liner having the overlay weld layer. With the method for manufacturing an inner liner for a hot extruder, which is characterized by comprising steps, it was possible to obtain an inner liner for a hot extruder that has high wear resistance. [Function] In the present invention, the inner liner base material is first subjected to solution treatment to make the structure of the base material regular, and then aging treatment is performed to improve the properties of the base material. Then, the super heat resistant alloy is overlay welded. If the build-up weld layer is made into a single layer, heat cracks may occur during extrusion work.As a result of considering this point, we found that by making the build-up weld layer a multiple layer of two or more layers, the This prevented heat cracks. After overlay welding, aging treatment is performed to bring out the characteristics of the overlay weld layer to its fullest. The aging temperature at this time is preferably set lower than the aging temperature of the base material in order to prevent softening of the base material. [Examples] The present invention will be described below based on Examples. Table 1 shows the main components of the inner liner base material in weight percent.

[Table] Heat treatment conditions for inner liner base material: Solution treatment 1130℃ x 1 hour oil cooling, aging 730℃ x 5 hours air cooling Heat treatment hardness of inner liner base material: Hv450 Welding method: MIG welding as shown in Figure 1. Inko 718φ1.2 MIG wire was used as the filling material. Welding conditions: Shown in Table 2. Parakeet 718 all over 2
After the first layer was built up, it was turned to a flat surface and then the second layer was applied. FIG. 2 is a cross-sectional view of the completed container.
Aging treatment conditions after overlay welding: 1st aging
720℃×8Hr furnace cooling → 2nd aging 620℃×8Hr
Air cooling Hardness of welded parts before and after aging treatment: As-welded state Hv290, after aging twice → Hv430 Using the inner liner manufactured as above, 6-4 brass (billet temperature 720℃) Approximately 24,000 tubes were extruded.
The conventional type had a lifespan of about 8,000 pieces, but the lifespan of the one according to the present invention has been significantly extended to about three times.
Moreover, since the cost is almost the same as the conventional one, its industrial value is great.

【table】

〔Effect of the invention〕

As explained above, according to the method for manufacturing an inner liner for a hot extruder of the present invention, it is possible to obtain an inner liner having high wear resistance, which is very useful industrially.

[Brief explanation of the drawing]

FIG. 1 is a schematic view of a liner overlay welding apparatus, and FIG. 2 is a sectional view of a container having a built-up liner. 1: Tire (outer cylinder), 2: Outer liner (intermediate cylinder), 3: Inner liner (inner cylinder), 4:
Super heat-resistant alloy overlay welding part, 5: Welding power supply device, 6,
7: Cable, 8: Gas cylinder, 9: Wire feeding device, 10: Torch, 11: Liner, 12: Liner rotation direction, 13: Carriage moving direction.

Claims (1)

[Claims] 1. (1) Solution treatment of the inner liner base material made of austenitic hot die steel, (2) Aging treatment of the inner liner base material, (3) A hot process characterized by comprising the steps of: forming two or more overlay layers by overlay welding a super heat-resistant alloy on the use surface; (4) aging-treating the inner liner having the overlay weld layer; A method for manufacturing an inner liner for an extruder.