JPH07108577A - Composite cylinder for plastic molding machine - Google Patents

Abstract

PURPOSE:To obtain a composite cylinder excellent in abrasion resistance and corrosion resistance by forming the lining layer applied to a cylinder matrix by sintering a powder prepared by uniformly dispersing a specific amt. of a WB powder in an atomized powder of a specific alloy. CONSTITUTION:A lining layer is formed on the inner surface of a cylinder matrix by applying a powder prepared by dispersing 4-50 pts.wt. of a WB powder in 100 pts.wt. of an atomized powder of an alloy consisting of 10-30wt.% of Cr, 0.5wt.% or less of Si, 1.0wt.% or less of Mn, 6.0-20wt.% of Mo, 0.7wt.% or less of C, 5.0wt.% or less of Fe, 2.0-10wt.% of W and the remainder of substantially Ni and inevitable impurities to the inner surface of the cylinder matrix to sinter the same under pressure by an HIP process. Heat treatment is applied to this composite cylinder to pref. form the metal structure of the matrix from 20% or more of bentonite and the remainder of sorbite in area ratio. By this constitution, the crack resistance of the lining layer can be enhanced.

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 in a plastic molding machine or the like and having excellent wear resistance and corrosion resistance.

[0002]

2. Description of the Related Art Cylinders for molding machines used for injection molding or extrusion molding of plastics and the like are provided, for example, in order to prevent corrosion or wear due to resin during resin molding or additives added to the resin. As disclosed in Japanese Patent Laid-Open No. 53-85712, a structure in which an alloy material having wear resistance and corrosion resistance is lined by a centrifugal casting method on the inner surface of a cylinder base material on a hollow cylinder made of steel is used. There is.

However, when the composite cylinder for a molding machine described above is manufactured by the centrifugal casting method, Fe of the steel material forming the cylinder base material penetrates into the alloy material forming the lining layer during the welding reaction. The penetration of Fe is necessary to carry out the welding between the lining layer and the cylinder base material,
Fe has a problem that it reduces the hardness of the lining layer and deteriorates the corrosion resistance.

Further, as an alloy material for forming the lining layer, in order to prevent the penetration of Fe from the base material and ensure the hardness and corrosion resistance of the lining layer, an alloy material is used as disclosed in JP-A-4-187746. It is used that the inner surface of a cylinder base material is pressure-sintered by a HIP (hot isostatic pressing) process.

However, in recent years, plastics have been used in various applications and various additives have been mixed, so that it is required to further improve the wear resistance and the corrosion resistance of the inner lining layer of the composite cylinder for a molding machine. It is rising. In particular, for the fluororesin molding, the corrosion resistance of the cylinder is further required. Therefore, it is necessary to add a large amount of alloy components or to add a large amount of wear-resistant components, but the centrifugal casting method may not always meet the above requirements due to problems such as segregation and dispersibility. Can not. Also H
Even if the inner surface of the cylinder base material is pressure-sintered by the IP process, there have been cases where the above requirements cannot be satisfied.

In order to solve these problems, in JP-A-4-187746, the alloy material for forming the lining layer is added with 5 to 60% by weight of WC, which is hard particles, to improve wear resistance. Is improving. However, if a large amount of WC is added to improve wear resistance, there is a problem that the strength of the lining layer is significantly reduced.

[0007]

An object of the present invention is that the lining layer is coated without having Fe penetrating from the cylinder base material, and has excellent corrosion resistance and wear resistance even in fluorine resin molding. The object is to provide a composite cylinder that retains its properties and can be made into a composition having excellent strength at the same time.

[0008]

As a result of earnest research in view of the above problems, the present inventor has optimized the composition of the alloy material for forming the lining layer, and at the same time, made HIP the alloy material.
By pressure sintering on the inner surface of the cylinder base material by the (hot isostatic pressing) process, Fe does not enter the lining layer, and the lining layer has excellent wear resistance, corrosion resistance, and strength. It discovered that it has and came to the present invention.

That is, in the composite cylinder comprising the lining layer and the cylinder base material layer of the present invention, the lining layer is
Cr 10 to 30% by weight, Si 0.5% by weight or less, M
n 1.0 wt% or less, Mo 6.0 to 20 wt%, C
0.1 wt% or less, Fe 5.0 wt% or less, W 2.0
10 to 10% by weight, and the balance is 4 to 50 parts by weight of WB powder per 100 parts by weight of atomized powder of an alloy consisting essentially of Ni and inevitable impurities.
It is characterized by being pressure-sintered on the inner surface of the cylinder base material by the process.

[0010]

The function of specifying the content (weight ratio) of each element will be described below.

Cr 10 to 30% In the Ni-Cr-Mo alloy to which the present alloy belongs, especially C
r is an element indispensable for maintaining the corrosion resistance against the oxidizing gas and the oxidizing atmosphere generated from the molding resin and the alkaline solution and the gas. If it is less than 10%, its action is insufficient and 3
If it exceeds 0%, the predetermined mechanical strength required for the present alloy, in particular, the toughness is insufficient.

Si 0.5% or less Similar to C, if it exceeds 0.5%, an intermetallic compound is formed at the grain boundary to easily cause grain boundary corrosion, and the solid solubility of Si in the matrix increases. Therefore, during use, cracking is likely to occur due to adhesion and heat effect due to galling of the screw or check ring, which causes a problem.

Mn 1.0% or less Mn acts as a deoxidizing agent, but due to its effect, the content is 1.0% or less.

Mo 6.0 to 20% Mo is effective in corrosion resistance similar to Cr, but particularly, it has a remarkable corrosion resistance to reducing gases and solutions such as F, Cl ₂ and SO ₂ generated in fluororesin molding. It is the alloy shown. 6.0
If less than 20%, the effect is insufficient, and if more than 20%, N
This is a problem because an i-Mo-based intermetallic compound precipitates at grain boundaries and causes embrittlement.

C 0.1% or less Ni-Cr to which the present alloy belongs, which mainly acts to maintain corrosion resistance
In the Mo-based alloy, if C exceeds 0.1%, carbides are formed at grain boundaries, grain boundary corrosion is likely to occur, and the solid solubility of C in the matrix increases. The necessary predetermined mechanical properties, especially toughness, are insufficient, and as with the above, cracks easily occur due to thermal influence, causing a problem.

Fe 5.0% or less Fe is effective for stabilizing Ni-Cr-Mo alloy and maintaining mechanical strength by containing a small amount of Fe, but if it exceeds 5.0%, it is generated by fluororesin molding. It is unfavorable because it is corroded by the fluorine gas and the like, which lowers the corrosion resistance.

W 2.0 to 10% In a Ni-Cr-Mo alloy, W is Ni-Cr-M
By forming a solid solution in the o alloy, it gives a stabilizing effect of the phase and an auxiliary action for improving the corrosion resistance, and also contributes to the increase of the hardness of the alloy. If it is 2.0% or less, its action is insufficient, and if it exceeds 10%, an intermetallic compound with W tends to be formed, and embrittlement occurs, which is a problem.

Remaining Ni Ni is an element showing the main effect of the present corrosion-resistant alloy, and is the residual weight% as a basic alloy of the present alloy.

4 to 50 parts by weight of WB powder In the present invention, the WB powder is further uniformly dispersed in the above alloy powder to improve hardness and wear resistance. W
A sintered alloy in which B powder is not added / dispersed has a problem that the hardness as a cylinder for a molding machine is too low, and wear, adhesion to a screw and a check ring, and galling are likely to occur. Hardness of the WB is HV 3700kg / mm ^2, significantly higher than the HV 1800 kg / mm ² in WC. Therefore, the increase in wear resistance and hardness is more remarkable than in the case of adding WC described in JP-A-4-187746. As an alternative to WB powder,
A boride powder other than W belonging to the IVa group, the Va group or the VIa group of the periodic table can also be used.

The particle size of the boride powder such as WB is 5 to
It is preferably 100 μm. If it is less than 5 μm, it will not be dispersed uniformly, and if it exceeds 100 μm, the strength of the lining layer will decrease, which is not preferable.

FIG. 1 is a schematic cross-sectional view showing a state in which a core metal for forming a lining layer is inserted into a cylinder base material, showing a state before alloy powder filling. As shown in FIG. 1, by inserting a core metal 2 for forming a cylinder portion of a composite cylinder inside a cylinder base material 1 having a hopper opening 41 and made of high-strength steel or the like, An annular hollow portion 3 is formed between the base material 1 and the core metal 2. Both ends of the core metal 2 and both ends of the cylinder base material 1 are sealed by joining the lids 4 and 5 by welding or the like. In this case, the alloy powder for lining is put through the opening 41,
Depending on the case, one of the lids 4 and 5 may be sealed after filling the alloy powder. The alloy powder is preferably filled by appropriately applying vibration to the cylinder base material. Finally, the hopper opening 41 is also sealed by the lid 8. The core metal 2 and the lids 4 and 5 are made of mild steel or the like. Further, the cored bar 2 does not have to be hollow as shown in the figure, and may be solid.

FIG. 2 is a schematic sectional view showing a state in which the alloy powder 3a is filled. A cylinder in which alloy powder is hermetically filled is loaded into a HIP device 7 having a structure as shown in FIG. 3 and HIP processing is performed. The usual HIP processing conditions are a temperature of 1000 to 1150 ° C. and a pressure of 1000 to 1500 atm.
And is performed for 1 to 5 hours in an atmosphere of an inert gas such as argon. The outline arrows in FIG. 3 schematically indicate the direction of pressure applied to the bonded body 6.

After the HIP treatment, the lids 4 and 5 of the joined body 6 are removed by cutting or the like. Next, the core metal 2 is removed, and the inner surface of the cylinder is finished. In the composite cylinder manufactured as described above, since the lining layer is sintered and formed by the HIP process, Fe does not excessively penetrate from the cylinder base material, and has excellent hardness and corrosion resistance.

The composite cylinder of the present invention described above is subjected to an appropriate heat treatment so that the cylinder base material has a metal structure that is advantageous in strength, so that the strength of the cylinder base material is improved and the crack resistance of the lining layer is improved. Can be improved. Therefore, it is preferable that 20% or more of the metal structure in terms of area ratio is bainite, and the rest is formed by sorbite.
If the bainite content is less than 20%, sufficient strength cannot be obtained, which is not preferable.

It is preferable to use a hypoeutectoid or eutectoid alloy steel as the most suitable cylinder base material when performing such heat treatment. When Cr-Mo steel is used as the alloy steel, the content of chemical components is C 0.3 to 0.5% by weight, and S is S.
i 0.15 to 0.35% by weight, Mn 0.3 to 1.5
% By weight, P 0.03% by weight or less, S 0.03% by weight
Below, Cr 0.7-1.5 wt%, Mo 0.1-
It is preferably 0.5% by weight in terms of strength. SCM440 specified by Japanese Industrial Standards (JIS G 4105),
Cr-Mo steel equivalent to SCM445 is particularly preferable in terms of strength.

When Ni--Cr--Mo steel is used as the alloy steel, the content of chemical components is 0.3 to 0.5% by weight of C, 0.15 to 0.35% by weight of Si, and 0.3 to Mn of Mn.
1.5% by weight, P 0.03% by weight or less, S 0.03
Wt% or less, Ni 3.0 wt% or less, Cr 0.7 to
From the standpoint of strength, it is preferable to use 1.5% by weight and 0.1 to 0.5% by weight of Mo. Japanese Industrial Standards (JIS G 410
Ni-Cr-M equivalent to SNCM439 defined in 3)
o Steel is particularly preferable in terms of strength.

In the present invention, since the base material has the above-mentioned metallographic structure, the composite cylinder is subjected to heat treatment. This heat treatment method will be described with reference to the heat treatment pattern of FIG. Here, the horizontal axis of FIG. 4 represents time, the vertical axis represents temperature, A on the heat treatment pattern is a quenching and heating step, B is a cooling step, C is a holding step,
D shows the tempering heating process. In the present invention,
After the 850 to 950 ° C. heating step shown in A, in the cooling step shown in B, the temperature is cooled to a temperature range where bainite transformation occurs, and the cooling rate at this time is 40 to 100 ° C./minute. If the cooling rate is less than 40 ° C./min, troostite is generated, and if it exceeds 100 ° C./min, cracks are likely to occur on the inner surface of the lining layer.

Next, a bainite transformation is caused by a holding step shown at C at 300 to 550 ° C. If the region in which bainite transformation is caused is less than 300 ° C, cracks are likely to occur on the inner surface of the lining layer due to transformation expansion of the cylinder base material at low temperatures, and if it exceeds 550 ° C, pearlite transformation occurs and the strength of the base material increases. Not granted. The holding time in the holding step C is 10 minutes or more. If the holding time is less than 10 minutes, the amount of bainite in the cylinder base material is less than 20%, and sufficient strength cannot be obtained.

Next, annealing is performed at a temperature indicated by E of 550 to 650.degree. If the annealing temperature is less than 550 ° C., the purpose of annealing for removing residual stress cannot be achieved, and 650
If the temperature exceeds ℃, it will affect the metal structure and reduce the strength of the base material. The annealing time is 1 to 5 hours. If the annealing time is less than 1 hour, the residual stress cannot be sufficiently removed.
The effect does not change significantly over time.

Finally, as shown in F, the temperature is cooled to room temperature.
In the composite cylinder of the present invention produced as described above, the strain of the lining layer is reduced because the strength of the cylinder base material is remarkably improved, and the lining layer has further excellent fatigue strength, particularly crack resistance.

[0031]

【Example】

Example 1 A joined body having the structure shown in FIG. 2 was produced by the method described above.
As an alloy material for forming the lining layer, Cr 16% by weight, Si 0.4% by weight, Mn 0.9% by weight, Mo
16% by weight, 0.06% by weight of C, 4.0% by weight of Fe, 4.0% by weight of W, the balance being 5 to 30 μm per 100 parts by weight of atomized powder of an alloy consisting essentially of Ni and inevitable impurities. 20 parts by weight of this WB powder were evenly dispersed. SCM440 was used as the cylinder base material. Then, the above-mentioned bonded body in which the powder was sealed was filled in a HIP device having a structure as shown in FIG. 3 and subjected to HIP treatment. The HIP processing conditions at this time are as follows: temperature 1100 ° C.
It was 0 atm, and a composite cylinder was obtained by carrying out in an Ar inert gas atmosphere for 4 hours.

Example 2 A bonded body was prepared in the same manner as in Example 1. As the alloy material for forming the lining layer, as in the example, 22% by weight of Cr, 0.3% by weight of Si, 0.5% by weight of Mn, Mo
11% by weight, 0.04% by weight of C, 3.0% by weight of Fe, 3.0% by weight of W, the balance of which is a particle size of 5 to 30 μm per 100 parts by weight of atomized powder of an alloy consisting essentially of Ni and unavoidable impurities. 30 parts by weight of the WB powder of was uniformly dispersed. The cylinder base material used here is SNCM439.
Is. Then, the above-mentioned bonded body in which the powder was sealed was subjected to the same HIP treatment as in Example 1 to obtain a composite cylinder.

Example 3 A composite cylinder obtained as in Examples 1 and 2 was heat-treated. The heat treatment conditions at this time are a heating temperature of 900 ° C. (A shown in FIG. 4), a cooling rate of 50 ° C./minute (B shown in FIG. 4), a temperature of 450 ° C. at which bainato transformation occurs, and a holding time of 20 minutes (shown in FIG. 4). C), the heating rate was 5 ° C./min (D shown in FIG. 4), the annealing temperature was 600 ° C., and the holding time was 5 hours (E shown in FIG. 4). The metal structure of the base material of the composite cylinder thus formed has an area ratio of about 60% bainite and about 40%.
It consisted of% Solvay.

With respect to the composite cylinder of this embodiment described above, the wear resistance and corrosion resistance of the lining layer and the strength of the cylinder base material were measured. For wear resistance, a sample of 10 mm × 15 mm × 10 mm in size was taken from the cylinder for the molding machine, and pressed against # 400 abrasive paper with a load of 2.0 kg.
After sliding for a distance of 80 m, the amount of wear of the lining material was examined. This result was expressed as a relative value when the result of the conventional nitrided steel cylinder of the comparative example was set to 10, and the wear resistance was evaluated.

Regarding the corrosion resistance, a sample having a size of 4 mm × 1.5 mm × 10 mm was taken from the cylinder for the molding machine,
After being immersed in a 10% HCl aqueous solution at 50 ° C. for 24 hours, the corrosion weight loss rate of the lining material was examined. This result
As a comparative example, the result of the conventional nitrided steel cylinder was expressed as a relative value when the result was 10, and the corrosion resistance was evaluated. Regarding the strength of the cylinder base material, a tensile test sample was taken from the base material, and 0.2% proof stress, which is the most important base material strength, was measured. The results are summarized in Table 1.

[0036]

[Table 1]

As is apparent from Table 1, in the composite cylinders of Examples 1 and 2, the lining layer has excellent wear resistance and corrosion resistance as compared with the conventional nitrided steel cylinder. In the composite cylinder of Example 3, since the appropriate heat treatment is performed, the strength of the cylinder base material is remarkably improved. Therefore, the strain applied to the lining layer is reduced, and the fatigue strength and crack resistance of the lining layer are improved.

In the present embodiment, a single-axis compound cylinder has been described as an example, but it is also possible to use a multi-axis compound cylinder, and in this case as well, good results can be obtained. Further, in the present embodiment, the core of the composite cylinder has a hollow structure, but it is of course that a good effect can be obtained even if the core has a solid structure.

[0039]

EFFECTS OF THE INVENTION The composite cylinder of the present invention has a lining layer made of an alloy having an optimum component composition in order to have not only high corrosion resistance required for fluororesin molding but also abrasion resistance. , And its alloy is HIP
It is configured to be pressure-sintered on the cylinder base material by the process. Therefore, the lining layer is coated without containing Fe that penetrates from the cylinder base material, and has excellent wear resistance and corrosion resistance. Further, since the strength of the cylinder base material is remarkably improved by appropriate heat treatment, the strain applied to the lining layer is reduced, and the fatigue strength and crack resistance of the lining layer are improved.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view showing a state where a core metal is inserted in a cylinder base material.

FIG. 2 is a schematic cross-sectional view showing a state in which a cylinder is filled with a lining alloy powder.

FIG. 3 HIP for manufacturing the composite cylinder of the present invention
It is a schematic sectional drawing which shows an apparatus.

FIG. 4 is a heat treatment pattern diagram of a composite cylinder according to an embodiment of the present invention.

[Explanation of symbols]

1 cylinder base material, 2 core metal, 3 hollow part, 3a
Alloy powder, 4, 5, 8 lid, 6 bonded body, 7
HIP device, 31, 32 ends, 41 hopper opening.

Claims (4)

[Claims] 1. In a composite cylinder comprising a lining layer and a cylinder base material, the lining layer is made of Cr 10-3.
0 wt%, Si 0.5 wt% or less, Mn 1.0 wt%
Hereinafter, Mo 6.0 to 20 wt%, C 0.1 wt% or less, Fe 5.0 wt% or less, W 2.0 to 10 wt%,
The balance is a composite for a plastic molding machine, characterized in that a powder in which 4 to 50 parts by weight of WB powder is uniformly dispersed is sintered per 100 parts by weight of an atomized powder of an alloy consisting essentially of Ni and unavoidable impurities. Cylinder. 2. The composite cylinder according to claim 1, wherein the metal structure of the cylinder base material is bainite 20 in area ratio.
% Or more, the remainder is sorbite, a composite cylinder for plastic molding machines. 3. The composite cylinder according to claim 2, wherein the cylinder base material is C0.3-0.5 wt%, Si.
0.15 to 0.35 wt%, Mn 0.3 to 1.5 wt%, P 0.03 wt% or less, S 0.03 wt% or less, Cr 0.7 to 1.5 wt%, Mo 0 1 to 0.
A composite cylinder for a plastic molding machine, characterized in that it is a Cr-Mo steel containing 5% by weight and the balance substantially Fe and inevitable impurities. 4. The composite cylinder according to claim 2, wherein the cylinder base material is C0.3-0.5 wt%, Si.
0.15-0.35% by weight, Mn 0.3-1.5% by weight, P 0.03% by weight or less, S 0.03% by weight or less, Ni 3.0% by weight or less, Cr 0.7- 1.5 wt%, Mo 0.1-0.5 wt%, balance substantially Fe
And a composite cylinder for a plastic molding machine, which is Ni-Cr-Mo steel composed of unavoidable impurities.