JPH0562573B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION TECHNICAL FIELD The present invention relates to a method for manufacturing a liner exclusively for a barrel of a twin-screw extruder, which is integrally attached to the inner surface of a barrel constituting a twin-screw plastic extruder, for example.

"Prior art and its problems" In recent years, with the increasing demand for engineering plastics, in the field of plastic molding, etc.
In order to extrude plastic materials while kneading them,
Twin screw extruders are becoming widely adopted.

This kind of twin-screw extruder has a twin-screw barrel with a pair of eyeglass-shaped holes and a twin-screw screw installed in the axial direction within the twin-screw barrel, and plastic materials, etc., are supplied to this twin-screw barrel. , heating the barrel from the outside and rotating the twin screws to knead it,
It is designed to be extruded from the discharge port.

By the way, the twin-screw barrel used in the above-mentioned twin-screw extruder has a hardened layer with excellent corrosion resistance formed on its inner surface to prevent corrosion or abrasion caused by the plastic materials kneaded inside. .

At present, the methods for providing a hardened layer on a biaxial barrel include forming a heat-resistant and corrosion-resistant alloy on the inner surface of the barrel by centrifugal casting, or using nitrided steel and nitriding it to form a hardened layer on the inner surface. Another method is to form a hardened layer by diffusion.

However, in the former case, the inner diameter of the biaxial hole is small because the hardened layer is formed by centrifugal casting.
Although it is effective for barrels with relatively short length dimensions,
There is a drawback that it cannot be applied to a barrel with a large inner diameter and a long length. Also, in the latter case,
Since the maximum thickness of the hardened layer formed is about 0.6 to 0.7 mm, there is a problem that the life of the barrel is short.

On the other hand, it is also possible to form the above-mentioned hardened layer as a biaxial liner separately from the barrel and attach and fix this liner to the biaxial hole, but the structure, precision, and joining condition corresponding to the biaxial hole may be considered. It is difficult to secure one, and currently it is not manufactured.

``Object of the Invention'' The present invention is a barrel for a twin-screw extruder that can be applied to any size of twin-screw barrel, has excellent corrosion resistance and wear resistance, and can also be applied to barrels with repaired inner surfaces of the twin-screw holes. The purpose is to provide a method for manufacturing a dedicated liner.

"Summary of the Invention" In the method for manufacturing a liner exclusively for barrels for twin-screw extruders according to the present invention, a pair of single-screw cylinders having an outer diameter and length corresponding to the inner diameter and length dimensions of the barrel for twin-screw extruders are provided. After forming a hardened layer that is harder than the liner base material on the inner surface of the liner base material, the liner base material is fixed with an accuracy maintaining jig and a part of each circumferential side is rotated while ensuring the required accuracy. The cut out liner base materials are cut into pieces with the same predetermined dimensions along the direction, and the cut surfaces of the cut liner base metals are butted together while still being fixed using the precision maintaining jig, and the butted parts are subjected to electron beam welding. The bonding is performed while maintaining the melting depth at a depth where the melted portion does not reach the hardened layer.

"Embodiment of the Invention" An embodiment of the method of the present invention will be described below in the order of manufacturing steps.

The liner base material 11 used is one for a uniaxial barrel. This liner base material 11 has an outer diameter and a length dimension that corresponds to the biaxial barrel 4 to be assembled.
0 corresponds to each inner diameter and length of the biaxial hole 41. The liner base material 11 has high corrosion resistance against, for example, resin that generates corrosive gases, and has a higher heat resistance than the barrel body base material in order to improve the adhesion of the outer surface of the liner to the inner surface of the barrel during operation. Molded from a material with a slightly high expansion coefficient. As such a material, for example, austenitic stainless steel such as SUS304 is preferable.

First, a pair of the liner base materials 11 having the same inner and outer diameters is prepared, and a hardened layer 12 having a harder material than the material of the liner base materials 11 is formed on the inner surface of each (FIG. 1). The hardened layer 12 is formed to a required thickness by, for example, hard facing or centrifugal casting. This hardened layer 12 is made of a material with excellent wear resistance, heat resistance and corrosion resistance;
For example, CO-based alloy, NIi-CO-based alloy or Fe-
Ni-based alloys and the like are preferred.

The liner base material 11 with the hardened layer 12 formed on its inner surface is then fixed to a pair of precision retaining blocks 20 (30), and precision retaining plugs 21 (31) are fitted into both open ends thereof. . These precision retaining blocks 20 (30) and precision retaining plugs 21
(31) works together to prevent the liner base material 11 from deforming. That is, the cylindricity and roundness required for the liner base material 11 and the division precision in the division and cutting process described below are ensured with high precision.
In Figure 2a, one of the pair is shown. The precision holding block 20 (30) has a holding bottom frame 2 having a width corresponding to the outer diameter of the liner base material 11.
2 (32), and a holding side frame 24 (34) and a holding side frame 25 (35) fixed to both sides of this holding bottom frame 22 (32) by fixing bolts 23 (33). The holding side frame 24 (34) and the holding side frame 25 (35) are provided with a tightening bolt 26 (36) and a tightening bolt 27 (3
7). Further, the outer diameter of the precision retaining plug 21 completely matches the inner diameter of the liner base material 11, so that it can be fitted into the openings at both ends of the liner base material 11 with zero accuracy error. Note that the upper ends of the holding side frame 24 (34) and the holding side frame 25 (35) are provided with a recess 28 (38) and a recess 29 in the longitudinal direction.
(39) is formed. This recess 28 (38)
and the recessed portion 29 (39) are formed in the liner base material 11, which will be described later.
In the butting process, the accuracy maintaining block 20
When 30 and 30 are butted together, a welding window 51 is formed.

Next, the liner base material 1 is fixed with high precision as described above by the precision holding block 20 (30).
1, with the precision retaining plugs 21 (31) fitted into its openings at both ends, the precision retaining block 20 (3
0) The part protruding from the upper end is along the resection line A in the axial direction.
- It is excised at part A (Fig. 2a). This excision is
For example, by milling machines and surface polishing machines, etc.
All of this is done by cutting and grinding while checking the accuracy. In this case, the diametrical height h of the liner base material 11 left by grinding is the distance D from the center of the bisector C of the biaxial hole 41 of the biaxial barrel 40 to the farthest inner peripheral surface. It corresponds with high accuracy.

After the liner base material 11 is cut into parts as described above, the cut surfaces are butted against each other while being fixed by the precision retaining block 20 (30) and the precision retaining plug 21 (31), and the precision retaining block 20 and 3
0 is further fixed with bolts or the like (not shown) (FIG. 3). For fixing, align the reference surfaces formed on the accuracy retaining blocks 20 and 30 (not shown), and align the abutted pair of liner base materials 1.
1. Ensure accuracy in the vertical and horizontal directions. The liner base materials 11 are now butted together with high precision.

After the liner base materials 11 are butted together, the butted portions are welded by electron beam welding to join them together (FIG. 4). The electron beam 45 is irradiated through the welding window 51. In this case, when the liner base materials 11 are butted together, the butted area becomes a V-shaped groove in the axial direction, so if the electron beam 45 is irradiated as is, it will solidify at the welded area due to solidification after welding. Defects such as cracks are likely to occur. Therefore, it is preferable to form, for example, a U-shaped groove 46 at the abutting portion, or to flatten the bottom surface. A portion 60 that is melted by the electron beam 45 during welding
The depth W is adjusted so as not to reach the hardened layer 12, as shown in FIG. This is liner base material 1
This is to prevent the melted portion 60 from reaching the hardened layer 12 and causing cracks, etc., since the materials of the hardened layer 12 and the hardened layer 12 are different.

Then, after leaving it at room temperature, the precision retaining blocks 20 and 30 are removed and the precision retaining plugs 21 and 31 are pulled out to obtain the biaxial liner L that protects the inner surface of the biaxial barrel 40.

As shown in FIG. 6, the obtained biaxial liner L has a hardened layer 12 formed on the inner surface of the biaxial hole 61 with a required thickness and high adhesion, and each liner base material 11 are butted together with high precision and firmly joined by the fused portion 60. Electron beam welding is intentionally not performed at the butt portions of the hardened layer 12 in order to prevent cracks from occurring due to differences in materials, but welding of the butt portions of the liner base material 11 is sufficient for sealing. ing. In addition, since the liner base material 11 is formed of austenitic stainless steel, even if corrosive gas enters through the butt gap between the hardened layers 12 that are not welded, the liner base material 11
Corrosion to 1 is avoided.

Then, by inserting and fixing the biaxial liner L into the biaxial hole 41 of the biaxial barrel 40, a liner-integrated biaxial barrel is obtained. Note that the insertion and fixing is performed, for example, by cold fitting, shrink fitting, press fitting, or the like. The liner base material 11 constituting the biaxial liner L includes a biaxial barrel 40
Since the coefficient of thermal expansion is slightly higher than that of the above, when this is inserted and fixed into the biaxial hole 41, the adhesion to the inner surface of the hole is extremely good. In addition, in the biaxial liner L obtained by the method of the present invention, the biaxial barrel 40
By selecting the liner base material 11 according to the length of the liner and the inner diameter of the biaxial hole 41, various sizes can be manufactured.

"Effects of the Invention" As explained above, the method of the present invention has excellent corrosion resistance and wear resistance, can be molded to a size corresponding to the barrel size, and can be applied to barrels after repair. A liner exclusively for the barrel of a twin-screw extruder can be obtained.

[Brief explanation of drawings]

Figures 1 to 3 show the method of the present invention in the order of steps. Figure 1 is a perspective view showing the hardened layer forming step, Figure 2a is a sectional view showing the high precision fixing and cutting process, and Figure 2 b is a partial sectional view taken along the line B-B in FIG. 2a, FIG. 3 is a sectional view showing the butt and welding process, and FIG.
FIG. 5 is a perspective view of a liner exclusively for barrels obtained by the present invention, and FIG. 6 is a side view of the liner obtained by the method of the present invention fixed to a barrel. 11... Liner base material, 12... Cured layer, 2
0, 30... Accuracy maintenance block, 21, 31...
Accuracy retention plug, 2232...Retention bottom frame, 24, 34
...Holding side frame, 25, 35...Holding side frame, 27,
37... Tightening bolt, 45... Electron beam, 40
... Biaxial barrel, 41... Biaxial hole, 51... Welding window, 60... Melting part, L... Biaxial liner.

Claims (1)

[Scope of Claims] 1 A pair of cylindrical liner base materials for a single screw extruder having an outer diameter and length corresponding to the inner diameter and length dimensions of the barrel body for a twin screw extruder has an inner surface that is harder than the liner base material. After forming a hardened layer, this liner base material is fixed with a precision maintaining jig, and a part of each circumferential side is divided into pieces with the same predetermined dimensions along the axial direction while ensuring the required precision. The resulting pair of liner base materials are butted together at their cut surfaces while still being fixed using the precision maintaining jig, and the butt portions are electron beam welded to a melting depth that does not allow the molten portion to reach the hardened layer. A method for manufacturing a liner exclusively for barrels for twin-screw extruders, which is characterized by joining while holding the liner. 2. In claim 1, the liner base material is a liner exclusively for the barrel of a twin-screw extruder, which is made of a material that has excellent corrosion resistance and has a slightly higher coefficient of thermal expansion than the barrel body. Production method. 3. A method for manufacturing a liner exclusively for a barrel for a twin-screw extruder according to claim 2, wherein the liner base material is made of austenitic stainless steel.