JP3329529B2 - Composite cylinder for plastic molding machine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a composite cylinder used for a plastic molding machine or the like, and more particularly to a composite cylinder for a molding machine having excellent wear resistance, corrosion resistance, seizure resistance and the like.

[0002]

2. Description of the Related Art In recent years,
Plastics are being used in a wide variety of applications as engineering plastics and polymer alloys, and as a result, various resins are mixed and used, or various additives are used. . For this reason, a lining layer in a cylinder of a molding machine used for injection molding or extrusion molding of these resins is desired to have excellent abrasion resistance and corrosion resistance.

For this reason, a cobalt-based alloy or a nickel-based alloy is used for the lining material, or a wear-resistant component such as WC is blended.

By using a cobalt-based alloy or a nickel-based alloy for the lining material, or by blending a wear-resistant component such as WC, the lining layer of the cylinder is hardened and the wear resistance and corrosion resistance are improved. In addition, there is a problem that galling, seizure, and the like easily occur between the cylinder and the screw.

As shown in FIG. 4, a cylinder 2, a screw 3, and a check ring (valve) 4 for preventing resin from flowing backward during injection are provided. An adapter 5 is attached to the tip of the cylinder 2. When the injection molding machine 1 is used to perform injection molding on the mold 6, the distance between the cylinder 2 and the check ring 4 is extremely small, about 0.02 to 0.2 mm. , The weight of the screw,
Both are constantly in contact with each other due to abnormal molding or the mixing of foreign matter. For this reason, galling and seizure are likely to occur between the cylinder 2 and the check ring 4 or between the cylinder 2 and the screw 3. This tendency is particularly remarkable in a horizontal injection molding machine that occupies most of the molding machine.

[0006] When galling or seizure occurs between the cylinder 2 and the check ring 4 or between the cylinder 2 and the screw 3 in this manner, the resin passing through the cylinder 2 is locally localized at the seizure-occurring portion. Overheated. As a result, defects such as resin burning and deterioration (deterioration or carbonization of the resin due to overheating) occur in the injection molded product.

In particular, in the case of resins having a low plasticization temperature and high transparency, such as polystyrene and polycarbonate, and white resins such as polyacetal, the above-mentioned baking and deterioration of the resin are remarkable.

[0008] In order to solve the above problems of the prior art,
The applicant has already provided a hollow cylindrical cylinder base material layer made of alloy steel, and a lining layer made of a cobalt-based alloy or a nickel-based alloy having excellent wear resistance and corrosion resistance on the inner surface of the cylinder base material layer. , 1 on the inner surface of the lining layer
An application has been filed for an invention which is a composite cylinder for a plastic molding machine in which a sulfurized layer or a sulfur-nitrided layer is formed to a depth of at least μm (Japanese Patent Application No. 4-11695).
No. 8).

In the above-mentioned improved invention, the sulfurized layer or the nitrosulphurized layer can be formed by performing a sulphidation treatment or a sulphonitridation treatment, respectively. The sulfurizing treatment can be performed by immersing the cylinder in a low-temperature salt bath (salt bath) in which an alkali base and a sulfurizing agent are dissolved at 100 to 150 ° C. for 1 to 3 hours. The treatment is performed by adding a nitrogen-containing alkali base and a sulfurizing agent to 500 to 580.
It can be applied by immersing the cylinder in a high-temperature salt bath which is melted at a temperature of 1 to 3 hours.

However, the above-mentioned improved invention has a problem to be further improved. In other words, since the sulfur bath or the nitrosulfurization requires salt bath equipment having a large volume enough to immerse the entire cylinder, there is a problem that the equipment cost increases. There is also a problem that it takes a long time (1-3 hours immersion) to form the sulfurized layer or the oxynitrided layer to a predetermined depth.

Accordingly, an object of the present invention is to solve the above-mentioned problems of the prior art and also to solve the problems of the improved invention, and it is hard and excellent in abrasion resistance and corrosion resistance. Another object of the present invention is to provide an excellent composite cylinder for a plastic molding machine.

[0012]

Means for Solving the Problems As a result of intensive studies in view of the above problems, the present inventor has determined that the lining layer of a cylinder for a plastic molding machine should be made of a cobalt-based alloy or a nickel-based alloy, and that this lining layer If an etching layer (corrosion layer with irregularities) having a depth of 1 to 30 μm is formed on the inner surface by etching, it is hard and excellent in abrasion resistance and corrosion resistance, and can greatly reduce galling and seizure. I found what I could do.

That is, the composite cylinder for a plastic molding machine according to the present invention comprises a hollow cylinder-shaped cylinder base material layer made of alloy steel, and an inner surface of the cylinder base material layer having excellent wear resistance and corrosion resistance. , Si, Mn, and Ni are 35% by weight or less, Fe is 20% by weight or less, and the balance is substantially a cobalt-based alloy composed of Co and unavoidable impurities, or Cr, B, Si, Mn. And C
a total of 35% by weight or less, 20% by weight or less of Fe, and a lining layer made of a nickel-based alloy having a balance substantially composed of Ni and unavoidable impurities. An etching layer is formed on the surface to a depth of 1 to 30 μm.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS First, the lining layer of the cylinder for a plastic molding machine according to the present invention will be described. The lining layer is made of a cobalt-based alloy or a nickel-based alloy.

The chemical components of the cobalt-based alloy are Cr, B,
It is preferable that the total of Si, Mn, and Ni is 35% by weight or less, Fe is 20% by weight or less, and the balance substantially consists of Co and inevitable impurities, particularly Cr 10 to 30% by weight, and B 1.5 to 4%. 0.0 wt%, Si4 wt% or less, Mn
It is preferable that it is composed of 2% by weight or less, Ni 5% by weight or less, Fe 20% by weight or less, and the balance substantially composed of Co and inevitable impurities.

Hereinafter, the alloy components of the Co-based alloy will be described. In a Co-based alloy, since Co alone cannot maintain wear resistance as a cylinder, Cr, B, Si, Mn
And Ni are preferably contained. However, Cr, B,
If the total amount of Si, Mn, and Ni exceeds 35% by weight, the strength and the corrosion resistance decrease.

The preferred content of Cr is 10.0-30.
0% by weight, and a particularly preferable Cr content is 11.0%.
２３23.0% by weight. Cr forms a hardened phase with a boride of Cr-B together with B, and improves the hardness of the alloy. If the Cr content is less than 10% by weight, the above-mentioned Cr-B phase is not sufficiently formed, while if it exceeds 30.0% by weight, the melting point of the alloy becomes 1200 ° C. or more. It is not preferable because it becomes difficult to form a lining layer on the substrate.

The preferred content of B is 1.5 to 4.0% by weight. B precipitates a high-hardness boride in the structure,
Has the effect of improving the hardness of the alloy, but 1.5% by weight
If it is less than 4.0%, the effect is not sufficient. If it exceeds 4.0% by weight, the eutectic structure becomes coarse and the brittleness increases, which is not preferable.

Although Si acts as a deoxidizing material, its content is set to 4.0% by weight or less from the effect.

Mn acts as a deoxidizer, but its content is set to 2.0% by weight or less from the effect.

Ni is a mixed element, and its content is 5.0% by weight or less. If the content of Ni exceeds 5.0% by weight, the hardness of the alloy is undesirably reduced.

The preferable content of Fe is 20.0% by weight or less, and the particularly preferable content of Fe is 8.0% by weight or less. Even if Fe is not initially contained in the alloy, it enters from the cylinder base material layer by a welding reaction with the cylinder base material layer made of steel. It is necessary for a predetermined amount of Fe to transfer from the cylinder base material layer to the alloy in order to perform complete welding between the lining layer and the cylinder base material layer. Further, when Fe is increased, the hardness is lowered, and the corrosion resistance to acid is lowered. When the content is more than 20.0% by weight, the influence cannot be ignored, which is not preferable.

Co is combined with Cr and B to improve the high hardness properties and corrosion resistance of the alloy.
And

Further, in the present invention, the wear resistance is further improved by dispersing 3 to 40 parts by weight of fine particles of a carbide of an IVa group, Va group or VIa group element per 100 parts by weight of the metal component of the Co-based alloy. Can be improved. Examples of carbides of the above-mentioned IVa group, Va group or VIa group element include WC, NbC, TiC, VC and the like. The carbide is preferably in the form of fine particles of 50 μm or less.

When the content of the carbide of the above-mentioned group IVa, Va or VIa element is less than 3 parts by weight, a sufficient effect due to its addition cannot be obtained.
The viscosity of the lining material increases, making it difficult to form a uniform lining layer. More preferred group IVa, V
The content of the carbide of the group a or group VIa element is 10 to 30 parts by weight per 100 parts by weight of the alloy component.

Next, the case of a Ni-based alloy will be described.
The chemical components of the Ni-based alloy are Cr, B, Si, Mn and C.
o is preferably 35% by weight or less, Fe is 20% by weight or less, and the balance substantially consists of Ni and unavoidable impurities, particularly 5 to 20% by weight of Cr and 1.5 to 4% of B.
0% by weight, Si 4% by weight or less, Mn 2% by weight or less, Co
10% by weight or less, Fe 20% by weight or less, balance substantially N
It is preferable that it is composed of i and unavoidable impurities.

In a Ni-based alloy, the wear resistance of a cylinder cannot be maintained only by Ni, so that Cr, B, S
It preferably contains i, Mn and Co. Where C
If the total amount of r, B, Si, Mn, and Co exceeds 35% by weight, the strength and the corrosion resistance decrease.

The preferred Cr content is 5.0 to 20.0.
% By weight, and a particularly preferable Cr content is 7.0 to 1%.
5.0% by weight. The content of B is 1.5 to 4.0% by weight. The content of Si is 4.0% by weight or less, particularly preferably 3.0% by weight or less. The content of Mn is 2.0% by weight or less.

The reasons for limiting the ranges of the contents of Cr, B, Si and Mn are the same as in the case of the Co-based alloy described above.

Co is a mixed element, and its content is 1
0.0% by weight or less. If Co exceeds 10.0% by weight, the hardness of the alloy is undesirably reduced.

The preferred content of Fe is 20.0% by weight or less, and the particularly preferred content of Fe is 8.0% by weight or less. The reason for limiting the range of the Fe content is the same as in the case of the Co-based alloy described above.

Further, in the present invention, the wear resistance is further improved by dispersing 3 to 40 parts by weight of fine particles of a carbide of an IVa group, Va group or VIa element per 100 parts by weight of the metal component of the Ni-based alloy. Can be improved. As the carbide of the above-mentioned IVa group, Va group or VIa group element, the same carbide as in the case of the above-mentioned Co-based alloy can be used.

In order to line the above-mentioned alloy on the cylinder base material layer, it is general to use a melting method of a metal typified by a centrifugal casting method. A method of sinter bonding by the HIP process may be used.

On the other hand, as a cylinder base material, Cr-Mo
Generally, steel materials such as steel, Ni-Cr-Mo steel, and Cr-Mn-V steel are used.

The composite cylinder for a plastic molding machine of the present invention is obtained by forming an etching layer having a depth of 1 to 30 μm on the inner surface of a lining layer made of the above-mentioned alloy.

Hereinafter, a method of forming an etching layer will be described. The etching layer is 10% HF at 10 to 20 ° C.
It can be formed by immersing a solution or a 10% HNO ₃ solution in the inner surface of the lining layer and corroding the lining layer. By performing this etching treatment, the corrosion reaction proceeds preferably for 5 to 10 minutes.

The etching layer obtained by the above-mentioned etching treatment has an uneven surface and has a thickness of 1 to 30.
μm, preferably 1 to 10 μm. Since the etching layer significantly reduces the coefficient of friction of the surface, the cylinder easily comes into contact with the active metal outermost surfaces of the cylinder and the valve or screw due to relative contact.
Even if its thickness is less than 1 μm, it exhibits the effect of preventing galling and seizure. However, even if it comes into intense contact with the valve or screw, it prevents the loss of the etching layer and maintains its function by 1 μm. The above depth is necessary. However, if the thickness exceeds 30 μm, metal peeling occurs, which is not preferable.

The hardness (HRC) of the lining layer obtained by the etching layer is about 50 to 60.

The etching process may be performed not only for a newly manufactured cylinder but also when the cylinder is seized or seized due to some abnormality during molding of the plastic. For example, when the degree of galling or seizure is light, the cylinder can be subjected to an etching treatment and then subjected to plastic molding again. Further, when the degree of galling or seizure is severe, the occurrence of galling or seizure can be prevented by polishing and removing the unevenness on the inner surface due to galling or the like and then performing an etching process.

Since such an etching process does not involve a change in the dimensions of the material to be processed, it is a very suitable method for modifying the inner surface of the cylinder.

The present invention will be described in more detail with reference to the following specific examples. (Example 1) Using a Cr-Mo steel equivalent to SCM440 specified in Japanese Industrial Standard (JIS G 4105),
A cylinder base material layer was formed.

Next, in order to form a lining layer,
A Co-based alloy having the composition shown in Table 1 was blended. In addition, since Fe transfers from the cylinder base material layer during casting, the mixing ratio was made in consideration of the amount of transferred Fe.

The alloy for the lining layer thus mixed is once melted by heating and then formed into a plate-like alloy casting.
This alloy casting was crushed and put into a cylinder through an opening for a hopper. After all openings were sealed, centrifugal casting was performed at 1200 ° C.

After slow cooling, tempering was performed at 630 ° C. for 5 hours to obtain a composite cylinder material. This material was finished to a predetermined size.

Then, the cylinder was degreased with an alkaline dilute solution, washed and dried with warm water, and hot water was allowed to flow over the inner surface of the lining layer to heat the entire cylinder to about 40 ° C.

Next, as an etching treatment, 10% H
The F solution is allowed to flow over the inner surface of the lining layer, and the corrosion reaction of the lining layer is allowed to proceed for about 9 minutes.
After drying, an etching layer having a depth of about 6 μm was obtained.

FIG. 1 shows a metallographic photograph of the inner surface of the lining layer after etching, which was taken with a scanning electron microscope.
Irregularities are formed on the inner surface by etching. As a comparison of this, FIG. 2 shows a metallographic photograph of the state before etching, that is, the inner surface of the lining layer after honing polishing, taken by a scanning electron microscope. In the figure, only polishing flaws in the oblique direction can be seen, but this becomes as shown in FIG. 1 by etching. The hardness of the cylinder base material layer (HSC) of this cylinder and the hardness of the lining layer (HRC)
Are shown in Table 2.

The cylinder thus obtained was assembled with a screw (YPT4 manufactured by Hitachi Metals, Ltd.) and a valve (YPT42 manufactured by Hitachi Metals, Ltd.) into an injection molding machine, and injection molding of polystyrene resin was performed for one month. During the operation, there was no galling or seizure between the cylinder, the screw and the valve, and no burning or dirt of the resin was observed.

Example 2 Japanese Industrial Standard (JIS G)
4103) Ni-Cr equivalent to SCM439 specified in
-A cylinder base material layer was formed using Mo steel.

Next, in order to form a lining layer,
A Ni-based alloy having the composition shown in Table 1 was blended. In addition, since Fe transfers from the cylinder base material layer during casting, the mixing ratio was made in consideration of the amount of transferred Fe.

The alloy for a lining layer thus mixed was centrifugally cast at 1100 ° C. in the same manner as in Example 1.

After slow cooling, tempering was performed at 600 ° C. for 5 hours to obtain a composite cylinder material. This material was finished to a predetermined size.

Then, the cylinder was degreased with an alkaline dilute solution, washed and dried with warm water, and hot water was passed over the inner surface of the lining layer to heat the entire cylinder to about 40 ° C.

Next, as an etching treatment, 10% H
Flow the NO ₃ solution over the inner surface of the lining layer and for about 9 minutes
After the corrosion reaction of the lining layer was advanced, it was washed again with hot water and dried to obtain an etching layer having a depth of about 6 μm. Table 2 shows the hardness (HSC) of the cylinder base material layer and the hardness (HRC) of the lining layer of this cylinder.

Further, the cylinder obtained in this manner is incorporated into an injection molding machine together with a screw (YPT4 manufactured by Hitachi Metals, Ltd.) and a valve (YPT42 manufactured by Hitachi Metals, Ltd.) to perform injection molding of polyacetal resin. After one month, there was no galling or seizure between the cylinder, the screw and the valve, and no burning or dirt of the resin was observed.

(Example 3) Cr-Mo similar to that of Example 1
Using a steel cylinder base material, alloy atomized powder having the composition shown in Table 1 and 20 parts by weight of WC having an average particle size of 5 to 30 μm uniformly dispersed in 100 parts by weight of the alloy atomized powder. And the HI having the structure shown in FIG.
P device (in the figure, 10 indicates a HIP device, 11 indicates a cylinder, and a white arrow indicates a pressure).
IP processing was performed. HIP conditions are 950 ° C., 100
0 atm, 4 hours in an Ar gas atmosphere.

The obtained composite cylinder material was subjected to finish processing to a predetermined size, and thereafter, this cylinder was subjected to the same etching treatment as in Example 1 to obtain a composite cylinder for a plastic molding machine. The thickness of the etching layer of the obtained cylinder was about 7 μm. The hardness of the cylinder base material layer (HSC) of this cylinder and the hardness of the lining layer (HR
C) is shown in Table 2.

The cylinder obtained in this manner was incorporated into an injection molding machine together with a screw (YPT7 manufactured by Hitachi Metals, Ltd.) and a valve (YPT42 manufactured by Hitachi Metals, Ltd.). When the composition containing the glass fiber was subjected to injection molding for one month, there was no galling or seizure between the cylinder, the screw and the valve, and no burning or dirt of the resin was observed.

[0059]

[Table 1]

[0060]

[Table 2]

(Example 4) A cylinder for a twin-screw extruder was manufactured from the same material as in Example 3 (no etching treatment was performed), finished to predetermined dimensions, and then this cylinder was used as it was. When incorporated in a twin-screw extruder together with a screw (made of stainless steel) and kneaded with a polyphenylene sulfide (PPS) resin, it was severely galled between the screw and the valve in one hour, causing seizure.

Therefore, the twin screw extruder was taken out, the inner surface of galling was removed by grinding, the same etching treatment as in Example 1 was carried out, the screw was assembled again, and extrusion molding was resumed. The problem of galling and burning was eliminated.

[0063]

As described above in detail, according to the present invention, an etching layer having a depth of 1 to 30 μm is formed on the surface of a lining layer of a composite cylinder for a plastic molding machine having a liner made of a cobalt-based alloy or a nickel-based alloy. Forming, it is possible to prevent galling, seizure, etc. between the screw or valve and the cylinder, thereby greatly reducing the frequency of occurrence of resin burning and abnormal molding of plastic molded products. .

Further, the service life of cylinders, screws, valves and the like can be greatly improved.

Further, an etching layer can be formed in a short time and easily without requiring a large-sized facility for performing the etching process.

[Brief description of the drawings]

FIG. 1 is a metallographic photograph of the inner surface of a lining layer of a cylinder for a plastic molding machine of Example 1 after the etching treatment, taken by a scanning electron microscope.

FIG. 2 is a metallographic photograph of the inner surface of the lining layer of the cylinder for a plastic molding machine of Example 1 before the etching treatment, taken by a scanning electron microscope.

FIG. 3 is a schematic view showing a HIP device for manufacturing a cylinder for a plastic molding machine according to a third embodiment.

FIG. 4 is a partial sectional view showing an example of an injection molding machine.

[Explanation of symbols]

1 injection molding machine, 2 cylinder, 3 screw,
4 Check ring, 5 Adapter, 6 Mold

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-6-210587 (JP, A) JP-A-60-13043 (JP, A) JP-A-4-22615 (JP, A) JP-A-4-210 185414 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B29C 45/00-47/96 C22C 19/00-19/07

Claims (2)

(57) [Claims] 1. A cylinder base material layer having a hollow cylindrical shape made of an alloy steel, and a total of 35 weight parts of Cr, B, Si, Mn and Ni having excellent wear resistance and corrosion resistance on an inner surface of the cylinder base material layer. % Or less, Fe is 20% by weight or less, and the balance is substantially a cobalt-based alloy having a composition consisting of Co and unavoidable impurities, or Cr, B, Si, Mn and Co.
Is less than 35% by weight, Fe is less than 20% by weight,
A lining layer composed of a nickel-based alloy having a composition substantially composed of Ni and unavoidable impurities,
A composite cylinder for a plastic molding machine, wherein an etching layer is formed on an inner surface of the lining layer to a depth of 1 to 30 m. 2. The plastic molding machine according to claim 1, wherein the lining layer is formed by dispersing 3 to 40 parts by weight of fine particles of a carbide of an element belonging to the group IVa, Va or VIa per 100 parts by weight of the metal component. Composite cylinder.