JPH0125362B2 - - Google Patents

Description

[Detailed description of the invention]

[Field of Industrial Application] The present invention is applicable to the production of cylinders with excellent corrosion resistance and wear resistance, which are used in injection molding or extrusion molding of various plastic materials, and other composite hollow members such as nozzles and composite metal pipes. It is about the method. [Prior Art] Since injection or extrusion molding of plastic materials as described above is carried out under considerably high temperature conditions, thermal decomposition of some raw materials cannot be avoided and it is natural that some corrosive gas will be generated. Some people do. In particular, when a halogen-containing compound is added for flame retardancy, a large amount of halogen-containing gas is generated. After that, the inside of the cylinder is constantly exposed to a corrosive environment, and the cylinder is required to have a high level of corrosion resistance. However, the pressure applied during molding is quite high;
In addition, inorganic fillers that are often added to improve strength have extremely high strength, so cylinders are also required to have a high level of wear resistance. Conventionally, nitrided cylinders such as SACM and SCM have been widely used as materials that meet these required characteristics, and these materials also have the characteristics of being inexpensive and easy to manufacture. However, since the hardened layer due to nitriding is extremely thin at about 0.1 mm, it cannot be said that it necessarily exhibits sufficient corrosion resistance and wear resistance. Therefore, a bimetallic cylinder made by centrifugal casting was developed as a cylinder that could withstand the harsh operating conditions mentioned above. Demand for this cylinder increased rapidly as it had much superior performance compared to conventional cylinders. I've been doing it. However, this bimetallic cylinder is not without its problems, and various problems remain as described below. In the centrifugal casting method, there is a limit to the melting point of the lining alloy due to manufacturing constraints, which is 1000 to 1100℃.
Limited to ingredients with melting points below. In the centrifugal casting method, high-hardness substances such as WC are added as reinforcing materials to improve wear resistance, but these reinforcing materials have a higher specific gravity than the matrix components, so they tend to segregate inside the lining layer and cause damage to the sliding surface. The amount present on the inner peripheral surface side is extremely small. The alloy melted during the centrifugal casting process naturally comes into contact with the back metal (steel material that makes up the cylinder body), but because a considerable amount of iron from the back metal mixes into the alloy layer, it does not have the expected corrosion resistance. I can't. Since sufficient centrifugal force cannot be obtained with a small-diameter cylinder, it is not possible to sufficiently improve the bondability of the lining material to the cylinder body. Since the lining alloy layer formed by centrifugal casting has a cast structure, component segregation is significant and intermetallic compounds are considerably coarsened. Therefore, the strength and toughness of the lining layer are not good, and the corrosion resistance and abrasion resistance are also uneven. [Problems to be Solved by the Invention] On the other hand, a shrink fit method has been known as a method for manufacturing a cylinder by forming a hardened layer on the inner peripheral surface of a back metal. However, this method has the following problems, especially when ceramic is used for the hardened layer (inner cylinder). Tolerance for shrink fit is 1/1000 to 15/100
Since it is approximately 0, even higher precision is required for finish grinding of the outer circumferential surface of the ceramic inner cylinder. For example, when manufacturing a small-diameter material with an inner cylinder outer diameter of about 10 mmφ, the shrink fit margin becomes small, making it difficult to implement the shrink fit method. This is because the temperature of the outer cylinder (back metal) cannot be raised very much (usually maximum temperature 600°C) because the absolute amount of shrinkage fit is small and the thermal shock resistance of ceramics is small. A technique as shown in FIGS. 2 and 3 has been proposed as a method for solving the problems of the prior art described above. The technology will be explained with reference to the drawings. As shown in Fig. 2, a circular inner pipe 3 is disposed on the inner circumferential side of a back metal 1 constituting a steel cylinder body, forming a substantially concentric annular hollow part 2, and a circular inner pipe 3 is provided for degassing. The upper part of the annular hollow part 2 is sealed with an upper lid 5 provided with a powder filling pipe 4 which also serves as a powder filling pipe 4, while the lower part is sealed with a lower lid 6. Next, a leak test is performed to confirm the sealing state, and then the powder filling process is started. That is, the raw material powder (metal powder or ceramic powder) 8 whose particle size has been adjusted is evenly filled into the annular hollow part 2 through the filling pipe 4. After filling is completed,
The inside of the annular hollow part 2 is completely degassed by evacuation while heating and then sealed in a vacuum state. The assembly, which has been filled with the raw material powder 8, deaerated and sealed, is loaded into the HIP device 9 as shown in FIG. 3 and subjected to HIP processing. After performing HIP treatment as described above, the upper and lower ends are cut and removed, and the peripheral surface is subjected to finishing such as BTA treatment and honing, and then the inner pipe 3 is removed. A cylinder for a plastic molding device in which a strong reinforcing layer is formed is obtained. However, some problems remain in the above method as well. In other words, when the cylindrical inner pipe 3 is used as a member for regulating the inner peripheral surface of the inner cylinder formed from the raw material powder 8, the inner and outer diameters of the inner pipe 3 are Because it expands and the degree of dimensional change (due to expansion) is uneven in the circumferential direction, it is difficult to predict dimensional changes in the final product. Further, in the final machining process, it is necessary to perform rough machining of the inner surface after removing the inner pipe 3 due to the above-mentioned dimensional change, resulting in poor yield. This tendency becomes particularly noticeable when ceramic fine powder, which is difficult to process, is used as the raw material powder. The present invention has been made in view of the above-mentioned circumstances, and its purpose is to provide a composite hollow member that can achieve higher dimensional accuracy during manufacturing and thereby improve productivity. The present invention aims to provide a method for manufacturing. [Means for Solving the Problems] The method of manufacturing a composite hollow member according to the present invention involves inserting a solid metal core for forming a hollow part into a metal tube constituting a back metal, and forming an annular shape between the two. The gist is that after a hollow part is formed and the annular hollow part is filled with raw material powder, the filled part is degassed and sealed, followed by HIP molding. [Operation] The operation of the present invention will be explained with reference to the drawings.
FIG. 1 is a schematic illustration of a steel cylinder manufactured according to the method of the present invention. The configuration shown in FIG. 1 is basically similar to the configuration shown in FIG. 2, and corresponding parts are given the same reference numerals. First, as shown in FIG. 1, a solid metal core (hereinafter referred to as inner metal) 3a for forming a hollow part is inserted into the inner peripheral surface of a metal tube constituting back metal 1, and the back metal 1 and inner metal 3a
An annular hollow part 2 is formed between the two. The upper and lower parts of the annular hollow part 2 are sealed by an upper lid 5 and a lower lid 6, respectively, which are provided with a raw material powder filling pipe 4 that also serves as deaeration. Back metal 1 is SCM440, SNCM439,
High-strength steel such as SUS304 and SUS316 is preferably used, and inexpensive mild steel is sufficient for the inner metal 3a, upper cover 5, lower cover 6, etc. Each of these members may be assembled by TIG welding or the like after thoroughly degreasing and cleaning the side facing the annular hollow portion 2. Next, the process moves to the raw material powder filling process, but before that, it is a good idea to perform a leak test to confirm the sealing state. If there is a large amount of leakage, it is necessary to perform repair welding. After completing the leak test, the raw material powder whose particle size has been adjusted is evenly filled into the annular hollow part 2 through the filling pipe 4. During filling, the uniformity of filling can be improved by applying appropriate vibration to the assembly. After filling is completed, the annular hollow part 2 is evacuated while being heated to completely remove the gas in the annular hollow part 2, and then sealed in a vacuum state. The assembly that has been filled with raw material powder, degassed, and sealed is loaded into the HIP device 9 as shown in Fig. 4.
Perform HIP processing. After performing HIP processing in this way, the upper and lower ends are cut and removed, and the inner peripheral surface is subjected to finishing processing such as BTA processing and honing to remove the inner metal 3a, thereby creating a strong inner surface. It is possible to obtain a cylinder for a plastic molding device on which a reinforcing layer is formed. The present invention is constructed as described above, but the point is that a hollow metal core (inner metal) is used instead of the cylindrical inner pipe 3 in the prior art as shown in FIG.
By using 3a, the following benefits can be obtained. (1) By using the solid inner metal 3a, the only dimensional change due to HIP processing is the shrinkage of the inner and outer diameters of the back metal 1, and there is almost no change in the outer diameter of the inner metal 3a, so the final It is possible to easily and accurately predict changes in the dimensions of the reinforcing layer that appear in the product shape. (2) If the outer diameter of the inner metal 3a is set to match the dimensions of the inner surface rough machining finish, only the removal of the inner metal 3a is sufficient for the rough machining in the final inner surface machining, and the lining reinforcement layer is The amount of machining is reduced and machinability is improved. (3) Since the dimensional accuracy is high, even when ceramics are used as the raw material powder 8,
Only a small amount of grinding is required after HIP treatment.
Since it can be omitted in some cases, productivity is significantly improved. As is clear from the above gist, the present invention is effective regardless of whether metal powder or ceramic powder is used as the raw material powder 8, but the requirements in each case are as follows. Although the composition of the metal powder used in the present invention is not limited at all, examples include corrosion-resistant and wear-resistant alloy powders having the chemical components shown below. C: 0.1 to 2.0% (weight%, same below) Si: 0.5 to 3.0% B: 0.5 to 3.0% Cr: 10 to 40% W: 10 to 30% Cu: 0.5 to 3.0% Balance: Ni: and/or Co The above chemical component ranges are based on consideration of corrosion resistance and wear resistance, and the reasons for each component range are as follows. C: 0.1-2.0% C is an indispensable element that forms carbides with Cr and W to improve wear resistance.
If the amount is less than %, the above effects will not be effectively exhibited. However, if C is too large, corrosion resistance and toughness will be poor, so it must be kept below 2.0%. A more preferable content of C is 0.5 to 1.5%. Si: 0.5-3.0% As will be described later, the cylinder according to the present invention is manufactured by obtaining alloy powder from a molten alloy having a predetermined chemical composition by an atomization method, and then obtaining a predetermined powder by hot isostatic pressing (HIP) or the like. Si is an essential element for increasing the fluidity of the molten alloy during atomization and making the powder particle size uniform, and if it is less than 0.5%, this effect will not be effective. Not demonstrated. However, if it is too large, it will have a significant negative effect on toughness, so it must be kept below 3.0%. A more preferable range of Si is 1.0 to 2.0%
It is. B: 0.5-3.0% B forms boride with Cr and W, contributing to improving corrosion resistance and wear resistance, and has the effect of increasing the hardness of Ni or Co matrix, and these effects are effectively exerted. Therefore, it must be contained at 0.5% or more. However, if it exceeds 3.0%, not only the toughness of the alloy decreases, but also the melting point of the alloy decreases excessively, making atomization and HIP operations difficult. A more preferable content of B is 1.0 to 2.0%. Cr: 10-40% Cr forms borides and carbides with B and C, and is also dissolved in the Ni or Co matrix, and is an essential element for improving corrosion resistance and wear resistance. The effects of this are not effectively exhibited, and the nitric acid corrosion resistance in particular becomes poor. However, if it is too large, the toughness of the alloy will decrease, so it must be kept below 40%. W: 10-30% W forms borides and carbides with B and C and has the effect of increasing corrosion resistance and wear resistance, and if it is less than 10%, these effects are not fully exhibited. But 30
%, the alloy becomes excessively hard and its toughness deteriorates. Cu: 0.5-3.0% Cu is dissolved in the Ni or Co matrix and particularly contributes to improving hydrochloric acid corrosion resistance. If it is less than 0.5%, the effect will not be exhibited effectively, while if it exceeds 3.0%, the toughness of the alloy will deteriorate. Remaining component: Ni and/or Co In order to ensure minimum corrosion resistance and wear resistance as a matrix component, the remaining component is Ni and/or Co. In addition, P, S, Fe, P, S, Fe,
Although trace amounts of Mn, Al, etc. may be mixed in, these do not have any particular adverse effect as long as they are contained in impurity amounts (approximately 1.0% or less). On the other hand, the ceramic powder is not limited in any way, but examples include those based on oxides such as Al ₂ O ₃ and PSZ. [Example] Example 1 C: 1.0%, Si: 3.2%, B: 3.08%, Ni: 13.75
%, Cr: 25.1%, W: 16.7%, Cu: 1.22%, the balance being substantially Co, and using an atomized metal powder with a particle size of 147 μm or less, the method of the present invention shown in FIGS. 1 and 4. A composite hollow member was manufactured. For comparison, Figures 2 and 3 were prepared using the above metal powder.
A composite hollow member was manufactured according to the conventional method shown in the figure. When filling each of the metal powders into the annular hollow part 2, the metal powders were degassed at 300° C. in a vacuum of 10 ^-5 orr for one hour, and then filled into the annular hollow part 2 under vacuum. After filling with metal powder, it is vacuum-sealed, and each assembly is loaded into the HIP device 9 as shown in Figures 3 and 4, and HIP treatment is performed at 930°C and 1000 kg/cm ² for 3 hours. Ta. As a result, the metal powder filling layer solidified to a density of 100% and was completely diffusion bonded, forming a thin corrosion-resistant metal layer on the inner surface of the back metal 1. The dimensional changes of the back metal 1, inner pipe 3 (prior art) and inner metal 3a (method of the present invention) in this case are shown in Table 1 below. The locations where the dimensions were measured are as shown in FIGS. 1 and 2 (cross-sectional view).

[Table] From the results in Table 1, the following can be considered. When the inner pipe 3 is used, no change in the dimensions of the back metal 1 is observed, but the inner and outer diameters of the inner pipe 3 change significantly for both types, 25.0 and 27.0 mm, each with a change of more than 2 mm. . Further, as the outer diameter of the inner pipe 3 changes, the amount of change in the metal layer also increases, and it is extremely difficult to predict the final size and adjust the size of the metal layer. In particular, the dimensional change is closely related to the packing density of the metal powder, and as the packing density is low, the amount of dimensional change naturally increases. In the case of long items such as plastic injection molding cylinders,
Even if the same metal powder is filled in the upper and lower parts of the cylinder, it is inevitable that the packing density will be uneven. Therefore, in the conventional technology using the inner pipe 3, the packed layer of metal powder is designed to be relatively large in consideration of safety, so that it does not exceed the minimum required size even when the filling rate is low. Therefore, in a healthy part with a sufficient filling rate, a considerably thick metal reinforcing layer is firmly formed, and it becomes necessary to grind the reinforcing layer, which requires a great deal of labor and extra metal powder, which is uneconomical. On the other hand, in the method of the present invention using the inner metal 3a, as is clear from Table 1, the outer diameter of the back metal 1 tends to shrink by 0.7 to 0.8 mm; The outer diameter does not change before and after HIP treatment. Therefore, the desired final product can be obtained by removing only the soft inner metal 3a in the machining process. That is, the metal reinforcing layer hardly needs to be ground. Note that the outer diameter of the back metal 1 will shrink slightly, but in this regard, rough processing can be performed using normal forging means or a rolling mill, so the dimensions should be set slightly larger so that the dimensions can be adjusted during the final finishing. If you do this, no problems will occur. Example 2 Next, an example in which ceramic powder is used as the raw material powder 8 will be explained. For convenience of explanation, the explanation will be given using FIGS. 6 to 8, but the basic structure is shown in FIGS. 1 and 4. There is no difference in the configuration from that shown, and corresponding parts are given the same reference numerals. The materials used for each member are as follows. Back metal 1: S45C [outer diameter 56mm, inner diameter 36mm
〓, 170mm] Inner metal 3a: SUS304 [Outer diameter 30mm〓] Top lid 5: S45C Ceramic powder: 3 mol Y ₂ O ₃ - ZrO ₂ (PSZ) Using the above materials, The inner metal 3a is inserted into the bottom cylindrical back metal 1, and the annular hollow part 2 formed by the back metal 1 and the inner metal 3a is filled with ceramic powder, thereby creating a filling pipe 4 which also serves as deaeration.
The upper part of the filled part (annular hollow part 2) is covered with the upper lid 5 provided with the above, and is degassed and sealed. Figure 7 shows the assembly in a sealed state.
0 is the welded part. Insert the assembly shown in FIG. 7 into the HIP device 9 as shown in FIG. 4 (or FIG. 3),
HIP treatment was performed at 1300°C and 1500 atm (Ar) for 1 hour. After that, the outer periphery of back metal 1 is turned and both ends are cut to form inner metal 3.
By removing a, a ceramic reinforcing layer 11 is formed on the inner peripheral side of the back metal 1 as shown in FIG.
A metal-ceramics composite structure tube was obtained. Although the ceramic reinforced layer 11 was not particularly finished by grinding, it was possible to obtain an accuracy of about 30±0.1 mm and a surface roughness of 1 s. This approximately corresponds to the surface finish accuracy of the inner metal 3a. Ceramics reinforced layer 1 formed in this way
No. 1 has a density of 6.10 g/cm ³ , which corresponds to a filling density (relative density) of 100%. The experiment was conducted under the same conditions as in the above example using a mixture of SiC and Vycor glass as the ceramic powder. A tube was obtained. According to the present invention, a metal-ceramic composite structure tube can be manufactured with high precision, so when a hardened layer is made of difficult-to-process ceramics, final finishing can be avoided as much as possible, which is particularly advantageous. . Further, according to the present invention, by variously changing the shape of the inner metal 3a, a metal-ceramic composite structure tube having a desired shape can be manufactured. For example, by using an inner metal 3b having a shape as shown in FIG. 9, a nozzle 12 as shown in FIG. 10 can be obtained. [Effects of the Invention] As described above, according to the present invention, by employing the above-described configuration, it is possible to further improve the dimensional accuracy during the manufacturing of various composite hollow members, and therefore, the production speed can be improved. This can greatly contribute to improving sexual performance.

[Brief explanation of drawings]

FIG. 1 is a schematic explanatory diagram of a steel cylinder constructed according to the method of the present invention, FIG. 2 is a schematic explanatory diagram showing the prior art, and FIG.
4 is a schematic explanatory diagram showing a state in which HIP processing is performed. FIG. 5 is a schematic explanatory diagram showing a state in which HIP processing is performed by the method of the present invention. FIG. 7 is a schematic explanatory diagram showing the manufacturing process when ceramic powder is used as the raw material powder, FIG. 7 is a sectional view showing the assembly shown in FIG. 6 in a welded and sealed state, and FIG. 8 is a metal-ceramics composite structure. 9 is a sectional view showing the tube, FIG. 9 is a side view showing the shape of the inner metal 3b, and FIG. 10 is a sectional view showing the nozzle 12. 1... Back metal, 2... Annular hollow part, 3...
...Inner pipe, 3a, 3b...Inner metal, 5...Upper cover, 6...Lower cover, 9...HIP processing device, 10...Welding part.

Claims (1)

[Scope of Claims] 1. A solid metal core for forming a hollow portion is inserted into a metal tube constituting the back metal to form an annular hollow portion between the two, and the annular hollow portion is filled with raw material powder. A method for manufacturing a composite hollow member, characterized in that the filled portion is then deaerated and sealed, followed by HIP molding. 2. The method for manufacturing a composite hollow member according to claim 1, wherein the raw material powder is an atomized metal powder. 3. The method for manufacturing a composite hollow member according to claim 1, wherein the raw material powder is ceramic powder.