JPH04368834A - Biaxial cylinder member - Google Patents

Abstract

PURPOSE:To improve and stabilize the protection function of the inner surface of a cylinder by a method wherein crack tending to develop at the chevron-like projections of lining layer is prevented from occurring and the separation and breaking off of the lining layer is prevented from occurring when the crack develops in the lining layer during the actual usage of the biaxial cylinder member concerned having the lining layer, which is made of sintered body and the inner side face of which forms a biaxial bore, on the inner wall of steel tubular body. CONSTITUTION:The biaxial cylinder member concerned is a three-layered laminated body having intermediate layer 20, which is made of corrosion-resistant alloy plate material and provided onto the inner surface of the bore of steel tubular body 10, and lining layer 30, which is made of sintered body formed through hot isostatic pressing, under the condition that the interfaces among the respective layers are bonded together metallurgically. The inner side face of the lining layer 3 is a biaxial bore produced by intersecting two circular arcuate faces. The radial section of the bonding interface between the intermediate layer and the lining layer is an elongated circular form.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cylinder member constituting a biaxial cylinder or the like of a plastic extrusion molding machine.

0002

[Prior art] The cylinder of a plastic extrusion molding machine is
A plurality of (approximately 7 to 10) hollow cylinder bodies (barrels) are used as cylinder members, and the end surfaces of the cylinder members are butted and connected to each other to be assembled. Conventionally, as the cylinder member,
Nitrided steel barrels have been used.

[0003] The cylinder of a plastic molding machine is subject to corrosion and wear due to the resin that is pumped through the hollow hole as the screw rotates. In recent years, as molding operations for reinforced plastics kneaded with ceramic fibers, etc., and flame-retardant plastics kneaded with flame retardants such as halogen compounds have increased, the useful life has been reduced due to corrosion and wear on the inner surface of the cylinder, and the burden of maintenance has increased. As a countermeasure, a lining layer made of a corrosion-resistant and wear-resistant alloy such as a nickel-based or cobalt-based self-fluxing alloy is formed on the hollow hole wall of the barrel to create a two-layer structure (double-layer barrel). Cylinders in which two-layer barrels are connected to each other or a two-layer barrel is connected in combination with a single-layer nitrided steel barrel are being put into practical use.

FIG. 6 shows the stacked shape of a conventional two-layer barrel. 10 is a barrel base material, and 30 is a lining layer. The barrel base material 10 is a cylindrical body made of an appropriate steel type (carbon steel, low alloy steel, etc.), and the lining layer 30 is formed on the inner wall of the cylindrical body 10 to have a uniform layer thickness (for example, 3 to 5 mm). has been done. The inner surface of the lining layer 30 is the wall surface of the twin-screw hole A where two arcuate surfaces intersect with a predetermined distance between the axes, and the intersection of the two arcs is a chevron-shaped protrusion that protrudes inward and faces each other. 21,21.

As a method for forming the above-mentioned lining layer, centrifugal force casting is mainly applied to uniaxial barrels in which the hollow hole has a simple perfect circular shape, but centrifugal force casting is mainly applied to biaxial barrels in which the lining layer has a cross-sectional shape in which two circular arc surfaces intersect. Since it is difficult to apply centrifugal force casting to barrels, various methods have been devised.For example, two uniaxial barrels with lining layers are prepared, and a part of each arc is oriented parallel to the axis. After cutting the barrel longitudinally, the cut surfaces are faced to each other and joined by welding, and a separately prepared cylindrical material is fitted and fixed as a lining member into the cylindrical hole of the barrel base material (steel cylinder). Recently, attempts have been made to form a lining layer as a sintered alloy layer using hot isostatic pressing.

[0006] In hot isostatic pressing, there are restrictions on the composition of the sintered alloy as in casting (for example, the combination and amount of alloying elements to avoid impairing the fluidity of the molten metal required for casting). The lining layer (sintered alloy) is highly dense and homogeneous under the uniform action of high pressure.
can be formed. Moreover, since the interface between the sintered alloy layer and the steel cylinder is provided with a strong bonding relationship through diffusion bonding during the sintering process, the cylindrical formed material can be mechanically fitted into the steel cylinder as a lining material. Compared to fixed methods, the laminated structure is more robust and stable.

[0007]

However, the above two-layer structure of the biaxial cylinder member has the following problems. One is that the lining layer formed by hot isostatic pressing has a chevron-shaped portion 21, 2 where two arcuate surfaces intersect.
This is a manufacturing problem in that cracks are likely to occur in the 1st part, and defects often occur in that part during finishing machining. The cracks in this chevron-shaped protrusion are thought to be due to the effect of thermal stress generated during the cooling process after hot isostatic pressing, but the Even if extremely slow cooling is performed at a rate of, for example, 40° C./hr or less, it is not easy to reliably avoid the occurrence of the above-mentioned cracks. The tendency for cracks to occur becomes more pronounced as the hardness of the sintered material increases, especially when hardness (HR) increases.
C) It is extremely difficult to form a sintered layer of approximately 62 or more without causing cracks.

[0008] Another problem is the problem of use, as shown in FIG. 7, when cracks C occur in the lining layer during actual use, corrosive substances from the plastic can enter the interior through the cracks. The base material 10 on the back side of the lining layer [Since it is covered and protected by the lining layer and is not expected to come into direct contact with the resin, corrosion resistance and wear resistance are not required when selecting the material, and carbon steel [Usually, low-alloy steel, etc. are used] is corroded, and as the damage D rapidly progresses, the lining layer 30 peels off and breaks down, and the effect of the two-layer structure quickly deteriorates. The problem is that it is lost. Damage to the base material on the back side of the lining layer and peeling/loss of the lining layer can occur on the inner surface of the nitrided steel single layer member 2 at the part where the two-layer structure member 1 is connected to the nitride steel single layer member 2, as shown in the figure. The same problem occurs when the end face of the base material 10 of the two-layer structure member 1 is exposed due to the progress of thinning d due to corrosion and wear. The present invention has been made to solve the above-mentioned problems regarding double-layered cylinders.

[0009]

[Means and effects for solving the problems] The biaxial cylinder member of the present invention is formed by hot isostatic pressing with a steel cylinder as an outer layer material and a corrosion-resistant alloy plate material as an intermediate layer on the inner surface of the cylindrical hole. The inner layer is made of a sintered body, and the interface between each layer is metallurgically bonded. It is characterized in that it forms a biaxial hollow hole with intersecting lines, and the bonding interface with the intermediate layer has an elliptical cross section in the radial direction.

In the biaxial cylinder member of the present invention having the above-mentioned three-layer structure, even if cracks occur in the sintered body layer during actual use and corrosive substances enter through the cracks, the corrosion-resistant intermediate layer The presence of the material blocks direct contact between corrosive substances and the base material, preventing rapid corrosion damage to the base material, and also prevents corrosiveness to the end face of the base material when connected to a cylinder member with a single layer nitrided steel structure. Contact of substances is also delayed by the presence of the intermediate layer, and as a result of these effects, the cylinder protection function of the lining layer as a corrosion/wear resistance layer is stably maintained over a long period of time.

[0011] Furthermore, in the biaxial cylinder member of the present invention, in which the radial cross-sectional shape of the lamination interface between the lining layer, which is a sintered body layer, and the intermediate layer is oval, the lining layer has a shape effect of the lamination interface. By relaxing and eliminating the stress on the chevron-shaped protrusion, the toughness of the chevron-shaped protrusion is increased, the occurrence of cracks and chips during machining is almost completely eliminated, and the hardness (HRC) is approximately 62. It is also possible to form a sintered body lining layer made of a highly hard material exceeding

[0012] The present invention will be explained below with reference to the drawings showing embodiments. In the figure, the same members as in FIG. 6 are given the same reference numerals. FIG. 1 shows a radial cross section of a biaxial cylinder of the present invention, and FIG. 2 shows a cross section taken along the line I--I.

In the figure, 20 is an intermediate layer. The material of the intermediate layer 20 is selected depending on the application and usage conditions of the cylinder, but for cylinder members for plastic molding machines, stainless steel, such as SUS316 austenitic stainless steel (12Ni-17Cr-2.5 Mo-Fe), etc. This is mentioned as a preferable example. The layer thickness is, for example, 3
~5mm.

Lining layer (inner layer) 30 which is a sintered body layer
are typically self-fluxing alloys such as nickel-based and cobalt-based alloys (e.g., Cr: 12-18%, Si: 2-7%, B:
2.5-4.5%, C: 0.5-1%, Fe: 3-7%
, Ni:Bal. Cr: 6-15%, Mo: 25-35
%, Si: 1-4%, Fe: 0.2-1.5%, C: 0
．． It is formed as a sintered alloy layer with various compositions designed according to the requirements such as corrosion resistance and wear resistance, including 1% or less Co:Bal), but it also contains metal and ceramic particles (carbide-based It can also be formed as a cermet sintered body, which is a mixture of cermets, nitrides, oxides, etc., or as a ceramic sintered body.

As shown in FIG. 3, the bonding interface between the lining layer (sintered body layer) 30 and the intermediate layer 20 in the biaxial cylinder member shown in FIG. The parts of two semicircular arc surfaces f2, f2 that surround each of them approximately concentrically, and the common tangent plane f to them
It has an elliptical shape consisting of a portion of 3 and f3. The inner surface of the lining layer 30 is different from that of the conventional type shown in FIG. 6 in that two arcuate surfaces f1 and f1 intersect to form a biaxial hollow hole A, and the intersection portion protrudes in a mountain shape. It won't happen. Note that the thickness of the lining layer 30 is, for example, 3 to 5 m.
m (semi-circular arc portion), and the intermediate layer 20 may have a uniform layer thickness over its entire circumference, and the layer thickness is, for example, 3 to 6 mm.

In the present invention, the portions f3, f3 between the two axes of the bonding interface between the intermediate layer 20 and the lining layer 30 do not necessarily have to be a strict plane as illustrated as a common tangent plane. For example, in FIG. 3, the dashed lines f3', f3
As shown in ', it may be a curved surface that curves gently inward. The degree of concavity of the curved surface is determined, for example, by the distance between two axes (L
) to the amount of depression (d/L) is approximately 0.1 or less, the spirit of the present invention is not impaired in any way.

Furthermore, the shape of the region between the two axes of the bonding interface may be a curved surface that bulges outward from the common tangent plane f3, f3, contrary to the curved surface f3', f3' that curves inward. I do not care. However, if the bulge height is too large, the thickness of the lining layer in that area will become unnecessarily thick.
This not only results in wasteful consumption of sintering raw material, but also reduces the compression densification effect of hot isostatic pressing on that part, so the ratio of the amount of bulge to the distance between the two axes is approximately 0.1.
It is appropriate to limit the amount to a certain extent.

Next, an example of manufacturing the biaxial cylinder member of the present invention will be described with reference to FIG. 4 and FIG. 5 showing a cross section taken along line II-II. The steel cylindrical body 10, which is the outer layer material, has a cylindrical hole 11 whose radial cross section is oval, and inside the cylindrical hole,
As the intermediate layer material 20, a corrosion-resistant alloy plate material such as a stainless steel plate is shaped into an oval cylindrical body that roughly matches the inner wall surface of the cylindrical hole 11, and is inserted into the cylindrical body. The core metal 50 is inserted into the inner space of the intermediate layer material 20. The core metal 50 is a columnar body having a cross-sectional shape in which two arcuate surfaces 52 intersect, corresponding to the hole wall of the biaxial hollow hole A of the sintered body layer (lining layer) to be formed. Note that 60 and 60 are cover plates that close both end faces of the steel cylindrical body 10, and are respectively joined to the end faces by welding.

As shown in the figure, the intermediate layer material 20 is fitted into the cylindrical hole of the steel cylindrical body 10, the core metal 50 is inserted into the inner space, and the space between the intermediate layer material 20 and the core metal 50 is The space is filled with sintering raw material powder (self-fusing alloy powder, etc.) P as a lining material. The inside of the powder-filled bed P and the fitting interface between the steel cylindrical body 10 and the intermediate layer material 20 are vacuum degassed (e.g. 1 x 10-2 Torr ), then remove the degassing pipes 61 and 62.
The powder layer is sealed by pressure bonding, and then subjected to a hot isostatic press to sinter the powder layer under pressure and heat. A strong bonding relationship is formed by diffusion bonding at the interface between the sintered body layer and the intermediate layer material 20 and the laminated interface between the intermediate layer material 20 and the steel cylindrical body 10, which are formed in the pressurizing and heating process. Ru.

After the sintering reaction is completed, the temperature is lowered to room temperature, the core metal 50 is removed by extraction or machining, and the inner surface of the lining layer 30 formed as a sintered body and the outer surface of the steel cylinder 10 are coated. Finish machining is performed to obtain the three-layer biaxial cylinder member shown in FIGS. 1 and 2. The above-mentioned hot isostatic pressing can be carried out according to a conventional method by appropriately setting the processing conditions (temperature, pressure, holding time, etc.) according to the type of sintering raw material powder, and cooling after the completion of the sintering reaction. The temperature can also be lowered by, for example, about 10℃ at a cooling rate of 40℃/Hr or lower.
It is only necessary to lower the temperature to 0°C or below, and no special restrictions or conditions are imposed.

In manufacturing the biaxial cylinder member of the present invention, the layer thickness of the sintered raw material powder filled between the intermediate layer material 20 and the core bar 50 is determined by There is a difference in thickness between the semi-circular arc part of compared,
A large volume shrinkage occurs due to the powder layer in the inter-axial region. Therefore, when the inner surface between the two axes of the intermediate layer material 20 is a flat surface 23, 23 as shown in FIG. The shape of the interface between the two axes is based on the original planes 23, 23 of the intermediate layer material.
However, as schematically indicated by chain lines f3' and f3' in FIG. 3, there is a tendency for the shape to be slightly concavely curved inward. As mentioned above, the elliptical shape of the bonding interface in the present invention is accompanied by such curvature, and there is no problem.

[0022]

Effects of the Invention The biaxial cylinder member with the three-layer structure of the present invention has a sintered body layer which is the lining layer of the biaxial hollow hole, which has high toughness and excellent crack resistance, and prevents chevron-shaped protrusions during machining. There are almost no occurrences of cracks or defects in the parts. In addition, this improved crack resistance makes it possible to create a crack-free and sound lining using high-hardness (e.g., HRc: 62 or higher) material, which was difficult or impossible to apply with conventional two-layer structures. This allows a large degree of freedom in selecting the material and designing the components of the lining layer. This makes it possible to further improve the corrosion resistance, abrasion resistance, etc. of the lining layer. Furthermore, in the process of actual use, even if cracks occur in the lining layer or damage occurs to the end surface of the connecting part, the presence of the intermediate layer prevents the back side of the lining layer from being damaged like in conventional cylinder members. It is difficult to cause rapid damage to the base material and the accompanying damage to the lining layer, and the cylinder protection function as a corrosion and wear resistant layer is stably maintained over a long period of time. Such improvement and stabilization of the protective function of the lining layer brings about effects such as improvement in the useful life of the cylinder, reduction in maintenance, and improvement in plastic operation efficiency.

[Brief explanation of the drawing]

FIG. 1 is a radial cross-sectional view showing an embodiment of a biaxial cylinder of the present invention.

FIG. 2 is a sectional view taken along the line II in FIG. 1;

FIG. 3 is an explanatory diagram of the laminated shape of the biaxial cylinder of the present invention.

FIG. 4 is an explanatory diagram of the manufacturing procedure of the biaxial cylinder of the present invention.

FIG. 5 is a sectional view taken along the line II-II in FIG. 4;

FIG. 6 is a radial cross-sectional view showing a conventional biaxial cylinder.

FIG. 7 is an explanatory cross-sectional view schematically showing damage to the inner surface of a conventional two-layer cylinder.

[Explanation of symbols]

10 steel cylinder, 20 intermediate layer, 30 lining layer (sintered body layer), 50 core metal, A biaxial hollow hole,
P Sintering raw material powder.

Claims (1)

[Claims] Claim 1: A steel cylindrical body is used as an outer layer material, and an inner layer made of a sintered body formed by hot isostatic pressing with a corrosion-resistant alloy plate material as an intermediate layer on the inner surface of the cylindrical hole, and an interface between each layer. is a three-layer laminate that is metallurgically bonded, and the inner surface of the inner layer made of sintered material forms a biaxial hollow hole in which two mutually parallel arcuate surfaces intersect, and the inner layer has a biaxial hollow hole formed by intersecting two mutually parallel arcuate surfaces. A biaxial cylinder member characterized in that the joint interface has an elliptical cross section in the radial direction.