JPH0584807A - Manufacture of screw for plastic molding - Google Patents

Abstract

PURPOSE:To provide the manufacturing method of a screw for plastic molding, which has high rigidity and, at the same time, corrosion resistance and wear resistance. CONSTITUTION:A screw main body made of material, which requires neither quenching nor annealing and has high rigidity even after fusing treatment, is divided to longer direction into a plurality of divisions. To the respective divisions, spraying materials 15, 16, 17 and 18, the degree of anticorrosion and of abrasion quality of which are different from one another, are sprayed longitudinally and continuously so as to form spray coated layer on the surface of the screw main body. Next, by heating the resultant screw in an inert gas atmosphere furnace or a vacuum furnace, fusing treatment is performed so as to diffusion-bond the spray coated layer to the screw main body in order to produce the screw concerned.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plastic molding screw used in an injection molding machine, an extrusion molding machine or the like, and more particularly to a screw having corrosion resistance and wear resistance.

[0002]

2. Description of the Related Art Since plastic molding is operated under high temperature and high pressure, the raw material resin is thermally decomposed and corrosive gas is generated, and a high hardness inorganic feeler is blended into the raw material. Screws for use are required to have corrosion resistance and wear resistance at high temperatures.

Therefore, in the conventional corrosion- and wear-resistant plastic molding screws, the outer surface of the screw body is subjected to nitriding treatment to increase the hardness of the surface to have wear resistance, or the surface of the screw body is subjected to Kanigen plating or hard. Corrosion and wear resistance is improved by applying chrome plating, and high wear resistance is achieved by quenching alloy tool steel.Furthermore, a screw with excellent corrosion resistance and wear resistance is applied by welding or spray plating I was making it. Conventional screw bodies generally use nitriding steel or chrome molybdenum steel.In the case of nitriding steel, nitriding treatment is performed, or in the case of chrome molybdenum steel, entire plating treatment is performed, or a part in the longitudinal direction is welded or sprayed. Then, a part or all of it is plated and used.

[0004]

In the conventional nitrided or plated screw, the hardened layer cannot be used for a long time because of its thin hardened layer. The nitriding screw is weak against corrosive gas and lacks corrosion resistance. Furthermore, in the case of welding deposits, especially those that are extended in the longitudinal direction, the accuracy of the screw may be reduced due to the twisting or bending of the screw body or the deviation of the flight twist angle due to the influence of heat. There is a problem. In the case of thermal spraying, in the case of structural alloy steel represented by conventional high-strength chrome molybdenum steel, the problem that the original material strength cannot be maintained due to the annealing state when fusing treatment is performed, so it means that only thermal spraying is performed. However, there is a problem that the microstructure is porous and the adhesion of the alloy is weak.

It is an object of the present invention to provide a plastic molding screw for an injection molding machine, an extrusion molding machine or the like which has high rigidity (high strength) and low cost, and has corrosion resistance and wear resistance.

[0006]

In order to achieve the above object, a screw for a plastic molding machine according to the present invention is provided with a plurality of thermal spraying materials having different characteristics on the outer surface of a screw body made of a highly rigid material in the longitudinal direction of the screw. Spraying the entire surface continuously,
After spraying, it is heated in an inert gas atmosphere furnace or vacuum furnace for fusing treatment to eliminate the porous structure of the sprayed layer, metallize the alloy, and at the same time, diffusion-bond it to the screw body.

[0007]

[Function] A plurality of thermal spraying materials are continuously sprayed on the high-rigidity material over the entire length, and after the thermal spraying, fusing (remelting) treatment is carried out in a gas atmosphere furnace or a vacuum furnace, resulting in excellent corrosion resistance and wear resistance. A high-strength plastic molding screw. For the high rigidity material, it is necessary to use a material that does not require quenching and tempering and that can maintain high tensile strength even after fusing treatment.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment will be described with reference to the drawings.
In FIG. 1, the screw 11 is divided into a, b, c, and d from the tip side and a plurality of thermal spraying materials having different characteristics are continuously sprayed on the surface of the screw body 12 (plasma spraying). The thermal spray material (powder) used was made by Colmonoy, Inc., USA. In this case it is as follows. No. B is No. 1 in consideration of corrosion resistance and wear resistance. No. 6 and No. 6 are also No. 6 in consideration of corrosion resistance and wear resistance. No. 70 and C are No. 70 in consideration of wear resistance. No. 5, D is the same material as C 5, but this one considered the corrosion resistance. The screw body 12 is made of non-heat treated steel having high rigidity (a material that does not require quenching or tempering, for example, NH48MV made by Kawasaki Steel. This material is also used for heating by fusing after thermal spraying described later. High tensile strength (tensile strength) can be maintained.

After continuously spraying different thermal spraying materials having different characteristics as described above, the screw 11 is vertically suspended in a gas atmosphere furnace 13 filled with an inert gas (argon gas) as shown in FIG. 5 minutes per minute by a rotating device not shown
The sprayed layer 14 is subjected to fusing treatment by heating to 1020 to 1050 ° C. while giving rotation of 10 revolutions. By this fusing treatment, the interface between the screw body 12 and the thermal spray layer 14 becomes diffusion-bonded and integrated.

After the fusing treatment, slow cooling (slow cooling) is performed in the furnace, and then the final processing of the entire screw 11 is performed.

FIG. 3 is a cross-sectional view of the screw 11 and the sprayed layer 1
No. 4 covers the entire peripheral surface of the screw body 12, and the thickness of the sprayed layer 14 is 0.5 to 0 mm as a finish.

The screw 11 thus manufactured is excellent in corrosion resistance and wear resistance and strong in strength. It is especially strong against twisting. In addition, the product does not cause peeling or cracking of the sprayed layer.

In the present embodiment, the example in which the gas atmosphere furnace is used as the heating furnace has been described, but it is also possible to use the vacuum furnace. Needless to say, it is also possible to use Kawasaki Steel's quenching and tempering-free material for the screw main body, and the same material as the manufacturer using the thermal spray material of Kormonoi Co. for the deposit.

[0014]

Since the present invention is constructed as described above, it uses a screw main body which is excellent in corrosion resistance and wear resistance under high temperature conditions and can withstand long-term use and has high strength. Therefore, the screw for plastic molding can be manufactured at a low cost because it is particularly strong in torsional strength and does not cause peeling or cracking of the sprayed layer.

[Brief description of drawings]

FIG. 1 is a front view of a plurality of thermal spray materials sprayed over the entire screw length.

FIG. 2 is a diagram showing heating and fusing treatment of a sprayed screw in a gas atmosphere furnace.

3 is a cross-sectional view taken along the line AA of FIG.

[Explanation of symbols]

 11 screw 12 screw body 13 gas atmosphere furnace 14 sprayed layer

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[Procedure amendment]

[Submission date] February 7, 1992

[Procedure Amendment 2]

[Document name to be amended] Statement

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[Document name] Statement

Patent application title: Manufacturing method of plastic molding screw

[Claims]

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a plastic molding screw used in an injection molding machine, an extrusion molding machine or the like, and more particularly to a method for manufacturing a screw having high rigidity, corrosion resistance and wear resistance. It is a thing.

[0002]

2. Description of the Related Art Since plastic molding is operated under high temperature and high pressure, the raw material resin is thermally decomposed and corrosive gas is generated, and a high hardness inorganic feeler is blended into the raw material. Screws for use are required to have high rigidity in addition to corrosion resistance and wear resistance at high temperatures.

Therefore, in the conventional corrosion- and wear-resistant plastic molding screws, the outer surface of the screw body is subjected to nitriding treatment to increase the hardness of the surface to have wear resistance, or the surface of the screw body is subjected to Kanigen plating or hard. Produces a screw with excellent corrosion and wear resistance by applying chrome plating to increase corrosion resistance and wear resistance, quenching alloy tool steel to increase wear resistance, and applying welding or thermal spray plating Was. Conventional screw bodies generally use nitride steel or chrome molybdenum steel.

[0004]

In the conventional nitriding or plating-treated screw, the hardened layer is thin so that it cannot withstand long-term use, and the nitriding screw is weak against corrosive gas and lacks corrosion resistance. There is. In addition, in the case of depositing by welding, especially for deposits that are long in the longitudinal direction, the accuracy of the screw may decrease due to the twisting or bending of the screw body or the deviation of the flight twist angle due to the influence of heat. There is a problem. In addition, in the longitudinal direction of the screw, although the degree of corrosion resistance and wear resistance differs depending on the classification, the surface treatment of the same property was performed over the entire length of the screw, so both corrosion resistance and wear resistance effects cannot be expected. It was Furthermore, in the case of thermal spraying, when the screw body is a structural alloy steel represented by high-strength chrome molybdenum steel, fusing treatment causes the screw body to become annealed, making it impossible to maintain the original material strength. In the case of a material with a high mechanical load, the screw may be damaged. When only the thermal spray material is sprayed, the microstructure of the sprayed layer is porous and the adhesion of the alloy is weak, resulting in delamination.

The present invention eliminates the above-mentioned drawbacks and has a high rigidity (high strength) even if a fusing treatment is performed, and an injection molding machine and an extrusion machine having different corrosion resistance and abrasion resistance depending on the longitudinal section of the screw. It is an object of the present invention to provide a method for manufacturing a plastic molding screw for a molding machine or the like.

[0006]

In order to achieve the above object, the method of manufacturing a screw for a plastic molding machine of the present invention requires a screw main body made of a material having high rigidity even after fusing treatment without quenching and tempering. It is divided into a plurality of parts in the longitudinal direction, and thermal spraying materials with different corrosion resistance and wear resistance are sprayed continuously in the longitudinal direction to form a sprayed layer on the surface of the screw body, and then an inert gas atmosphere furnace or vacuum furnace. This is a method of producing by fusing treatment by heating inside and diffusingly bonding the sprayed layer formed by spraying to the screw body.

[0007]

[Operation] The longitudinal direction of the screw main body made of high-rigidity material is divided into a plurality of sections, and thermal spraying materials with different corrosion resistance and wear resistance are sprayed continuously in the longitudinal direction for each section to form a thermal spray layer on the surface of the screw main body. After being formed, it is subjected to fusing (remelting) treatment in a gas atmosphere furnace or a vacuum furnace to diffuse-bond the sprayed layer to the screw body to produce a screw for plastic molding which is excellent in corrosion resistance and wear resistance and high in strength.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of the present invention will be described with reference to FIGS. In this embodiment, an example of a general screw 11 used in a plastic extruder will be described. Screw 1
The shape of No. 1 is, in order from the tip side, a measuring section a for measuring the kneading of the molten resin and a uniform flow rate, a compression section b for melting and compressing the raw material resin, and a supply section c for feeding the raw material resin to the tip side. , A bearing portion that supports one end of the screw. Thermal spraying materials (powder) 15, 16, 17, and 18 having different degrees of corrosion resistance and wear resistance for each of these sections are continuously sprayed in the longitudinal direction to form thermal sprayed layers.

On the other hand, the screw main body 12 is made of a material that does not require quenching and tempering, and is made of a high-rigidity material that can maintain high tensile strength (high tensile strength) even after fusing treatment after thermal spraying, which will be described later, so that cracks do not occur in the thermal sprayed layer. In the furnace immediately before thermal spraying
It is preheated to 800 ° C and then sprayed.

With respect to the thermal spray material sprayed for each section in a general screw, the measuring section (i) has a hardness of HRC55 to HRC55 in consideration of corrosion due to a corrosive decomposition gas generated from a flame retardant or the like and wear accompanied by corrosion. Ni is about 60,
For the thermal spray material 15 based on Cr, Si, B, the compression part b has a hardness similar to that of the measuring part a, and a material having a high degree of wear in consideration of the wear resistance due to the compression of the raw material resin, for example, A thermal spray material 16 containing WC based on the components Ni, Cr, Si, B is used, which is provided with wear resistance and corrosion resistance. Further, the supply part C may have a little less wear and corrosion resistance than the above-mentioned tip side measuring part a and the compression part b, but as a material which is easy to process the screw, the hardness Ni is about 50 to 55 and the components Ni and WC are high. , Cr, Si, B based thermal spray material 17, and bearing D has hardness HR in consideration of workability even if wear resistance and corrosion resistance are lower than those of supply portion C.
The thermal spray material 18 having the components Ni, Cr, Si, and B as the base is sprayed at about C45 to 50. As described above, the screw 11 is the most suitable thermal spray material 15, 16, 1 according to the molding conditions.
7 and 18 are selected and used for each category.

The sprayed layer 14 formed by spraying the sprayed materials 15, 16, 17, 18 covers the entire peripheral surface of the screw body 12 as shown in FIG. 3 (transverse sectional view), and the thickness of the sprayed layer 14 is 0. It is 5 to 1.0 mm. By the way, the following materials were used as the material of the screw main body and the thermal spray material used in this example. The screw body 12 is NH48M made by Kawasaki Steel.
V, thermal spray materials 15, 16, 17, and 18 are manufactured by Colmonoy Co., and thermal spray material 15 is No. 6, thermal spray material 16 is No. 75,
The thermal spray material 17 is No. 70, the thermal spray material 18 is No. 5 was used. Of course, it is possible to use equivalent materials of other companies. In addition, in the present embodiment, the screw 11 is connected to the measuring unit a,
Although the description has been given with an example in which the compression section B, the supply section C, and the bearing section D are divided, the invention is not limited to this, and it can be divided into a plurality of sections as needed, and thermal spraying materials with different corrosion resistance and wear resistance suitable for that section can be sprayed. Of course, it is possible to do so.

After the thermal spraying materials having different properties are continuously sprayed in the longitudinal direction as described above, an atmosphere furnace 13 filled with an inert gas (argon) is provided as shown in FIG. 2 in order to perform oxidation prevention and soaking and heating. The screw 11 is vertically suspended therein, and is heated at 1020 to 1050 ° C. while being rotated at 5 to 10 revolutions per minute by a rotating device (not shown) to fuse the sprayed layer 14. Thermal sprayed layer 1 by this fusing treatment
4 is melted and diffusion-bonded to the screw body 12 to be integrated.

After the fusing treatment, the sprayed layer is gradually cooled (slowly cooled) in the furnace so that cracks do not occur in the furnace, and then the surface of the sprayed layer 14 sprayed is finished into a final screw shape by a grinding machine. In this embodiment, the example using the gas atmosphere furnace is described, but it is also possible to use a vacuum furnace.

The manufacturing sequence of the plastic molding screw thus manufactured will be described with reference to FIG. 4 (flow chart). First, processing S1 of the screw body 12 (STEP
In 1), the screw main body (matrix) 12 is machined into a final sprayed layer, that is, a size obtained by subtracting 0.5 to 1.0 mm. Next, put in a heating furnace at S2 and 700 to 800 ° C.
Preheated to S3
Plasma spraying of 5, 16, 17 and 18 is performed. The thickness of the sprayed layer is sprayed to a size that allows for the shrinkage margin due to fusing and the machining margin due to cutting. That is, thermal spraying is performed so that the final sprayed layer 14 has a thickness of 0.5 to 1.0 mm. Next, in heating fusing S4, it is put in the gas atmosphere furnace 13 and heated to melt the sprayed layer to diffuse-bond it to the screw main body 12, and then gradually cooled in the same furnace in S5, and in S6 the final shape of the screw 11 is obtained. Grind.

The screw 11 thus manufactured is excellent in corrosion resistance and wear resistance and strong in strength. It is especially strong against twisting. Further, the screw 11 does not cause peeling or cracking of the sprayed layer.

[0016]

EFFECTS OF THE INVENTION In the present invention, unlike the conventional one coated with a metal having the same corrosion resistance and wear resistance over the entire length of the screw, each section is coated with a spray material suitable for the molding material and the molding conditions. Strong against corrosion and wear resistance in
Withstands long-term use and has high strength, it is strong against twisting and has a remarkable effect without peeling or cracking of the sprayed layer.

[Brief description of drawings]

FIG. 1 is a front view in which a different thermal spray material is sprayed for each section over a longitudinal direction of a screw.

FIG. 2 is a diagram showing heating and fusing treatment of a sprayed screw in a gas atmosphere furnace.

3 is a cross-sectional view taken along the line AA of FIG.

FIG. 4 is a flowchart showing a manufacturing order.

[Description of Reference Signs] 11 screw 12 screw body 13 gas atmosphere furnace 14 thermal spray layer 15 thermal spray material 16 thermal spray material 17 thermal spray material 18 thermal spray material

[Procedure 3]

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[Procedure amendment 4]

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[Figure 4]

Claims (2)

[Claims] 1. A plurality of thermal spraying materials having different characteristics are continuously sprayed on the entire outer surface of a screw body made of a highly rigid material in the longitudinal direction of the screw, and then heated in an inert gas atmosphere furnace or a vacuum furnace after the thermal spraying. Then, the fusing treatment is performed, the sprayed layer is metalized, and the screw is bonded to the screw body. 2. The screw for plastic molding according to claim 1, wherein the high-rigidity material is a material that does not require quenching and tempering and is capable of maintaining high tensile strength even after fusing treatment.