JP5095669B2 - Cylinder lining material for centrifugal casting and centrifugal casting method for producing cylinder lining material - Google Patents

Description

  The present invention relates to a cylinder lining material formed on an inner peripheral surface of a cylinder body by a centrifugal casting method and a centrifugal casting method for manufacturing the cylinder lining material.

  With an injection molding machine, resin products having various characteristics, shapes, strengths, and the like are manufactured using various resin raw materials and resin raw materials obtained by mixing glass fibers and the like. A molding cylinder used in such an injection molding machine is required to be excellent in high hardness, corrosion resistance, durability and the like and to be manufactured at a relatively low cost. In response to the demand, a forming cylinder in which a cylinder lining material is formed on the inner peripheral surface of a cylinder body by a centrifugal casting method or a manufacturing method thereof has been proposed.

  For example, Patent Document 1 discloses a cylinder of an injection molding machine manufactured by a centrifugal casting method, in which a substantial part of tungsten carbide particles is dispersed and mixed in a concentrated nickel or concentrated cobalt alloy matrix on the inner surface of the cylinder. A cylinder of an injection molding machine having a layer has been proposed. The specification states that for convenient machining and finishing of the inner surface of the cylinder after centrifugal casting, it is desirable and preferred that tungsten carbide be dispersed in the main part rather than over the entire cross section of the casting lining. Is said to be about 40 to 80% of the volume of the lining. In the invention according to the present proposal, it is described that the tungsten carbide particles used are desirably relatively small particles, preferably 100 mesh, and more preferably 200 mesh or smaller particles.

  Patent Document 2 discloses a tungsten carbide composite lining material for centrifugal casting in which tungsten carbide particles are dispersed in a nickel alloy matrix using a raw material containing 8 to 25% iron and 30 to 45% tungsten carbide as composition components. Has been proposed. According to the specification, in a lining material in which a boride or carbide is combined with a conventional Ni base or Co base manufactured by centrifugal casting, the boride contained therein has poor thermal stability and hardness. As a result, the carbides damage the mating material, and the wettability with the matrix such as Ni-base and Co-base is poor, and there are problems such as easy cracking. The tungsten carbide composite lining material for centrifugal casting according to the present proposal uses spherical tungsten carbide powder having an average particle diameter of 1 to 12 μm as a tungsten carbide raw material, and it is described that there was no problem such as cracking. ing.

  In Patent Document 3, in a cylinder for a molding machine in which a lining layer containing a wear-resistant and corrosion-resistant alloy is formed on the inner surface of a hollow cylindrical steel outer cylinder, the lining layer includes a base containing nickel, and metal tungsten There has been proposed a cylinder for a molding machine characterized by comprising hard particles in which tungsten carbide is dispersed. Further, Patent Document 3 proposes a molding machine cylinder in which tungsten boride is dispersed in a lining layer. According to the specification, tungsten carbide having a relatively small particle size such as an average particle size of 6 to 12 μm is easily melted and decomposed at the time of heating and melting in actual production, and is difficult to be included in the lining layer of the cylinder As a result, a test result is disclosed in which hard particles in which tungsten carbide is dispersed in metallic tungsten having a maximum length of 55 to 305 μm at the time of product are mixed with a base alloy powder and subjected to centrifugal casting.

Japanese Patent Publication No.54-32413 JP 7-290186 A JP 2008-201080

  In general, when producing a cylinder for a molding machine having a lining layer in which tungsten carbide or tungsten boride is dispersed in nickel, cobalt or an alloy base thereof by centrifugal casting, tungsten carbide or tungsten boride having a high specific gravity is used. A cylinder lining material is manufactured which is divided into a highly dispersed outer circumferential portion and an inner circumferential portion which is rich in nickel, cobalt or alloys thereof having a low specific gravity and is rare in tungsten carbide or tungsten boride.

  The cylinder material for the molding machine manufactured by the centrifugal casting method is processed into the cylinder for the molding machine by applying the inner surface processing of the cylinder lining material, but the portion in which tungsten carbide and tungsten boride are dispersed (lining layer) Is hard and difficult to machine. For this reason, the invention described in Patent Document 1 is positive for a layer (nickel, cobalt, or an alloy rich layer thereof) rich in nickel or cobalt that is softer and easier to machine than the part and rare in tungsten carbide or tungsten boride. It is trying to provide.

  However, the smaller the number of cutting parts for finishing the cylinder for a molding machine, the better. In patent document 2 or 3, there is no description about making nickel, cobalt, or these alloy rich layers positively small. In addition, there is no example disclosed in the prior art regarding a method capable of controlling the thickness of nickel, cobalt, or an alloy rich layer thereof.

  The tungsten carbide composite lining material for centrifugal casting proposed in Patent Document 2 describes that the dispersibility of tungsten carbide particles can be improved by adding an iron component, and the lining strength can be increased. To improve the abrasion resistance and corrosion resistance of the layer, an iron component is not preferable. Moreover, the cylinder for a molding machine proposed in Patent Document 3 has a problem that special hard particles in which tungsten carbide is dispersed in metallic tungsten must be prepared.

  In view of such conventional problems, the present invention uses tungsten carbide powder and tungsten boride powder that are readily available, and tungsten carbide particles and tungsten boride particles are contained in nickel, cobalt, or an alloy base thereof. A cylinder lining material having a dispersed lining layer and a nickel, cobalt or alloy-rich layer (particle-depleted layer) having a very small thickness, or a cylinder lining material having a particle-depleted layer having a desired thickness. An object of the present invention is to provide a cylinder lining material for centrifugal casting suitable for producing a cylinder lining material excellent in wear resistance, and a centrifugal casting method for producing such a cylinder lining material.

The cylinder lining material for centrifugal casting according to the present invention is, by mass%, tungsten boride + tungsten carbide (total amount): 30 to 45%, tungsten boride / tungsten carbide: 1 or less , tungsten boride: 5 to 20%, nickel + cobalt (total amount): 35-50%, molybdenum: 1% or less, chromium: 10% or less, boron: 1-3%, silicon: 1-3%, manganese: 2% or less, iron: Contains 5% or less, carbon: 1% or less, and inevitable impurities.

  In the above invention, tungsten carbide is preferably a spherical powder having an average particle size of 6 to 12 μm, and tungsten boride is preferably a powder having an average particle size of 3 to 12 μm.

The centrifugal casting method according to the present invention includes a lining layer in which tungsten carbide particles and tungsten boride particles are dispersed in a nickel and / or cobalt alloy base provided on an inner peripheral surface of a cylinder body, and an inner peripheral surface of the lining layer. A centrifugal casting method for producing a cylinder lining material having a particle-depleted layer, the tungsten carbide particles and the tungsten boride particles being rare, and containing 5 to 20% tungsten boride powder by mass% Using a raw material in which the powder mass is equal to or greater than the tungsten boride powder mass, the total mass of the tungsten carbide powder and the tungsten boride powder is 45% or less, and the balance is a nickel and / or cobalt alloy base forming component, By adjusting the mass ratio with the tungsten boride powder, the thickness of the particle-depleted layer It is carried out by controlling the.

  In the invention of the centrifugal casting method, the tungsten boride powder is preferably 0.14 to 1.00 in mass ratio with respect to the tungsten carbide powder. Further, the interval between tungsten carbide particles in the lining layer can be set to 8 to 50 μm.

  According to the present invention, a tungsten carbide powder, tungsten boride powder, which is readily available, is used and has a lining layer in which tungsten carbide particles and tungsten boride particles are uniformly dispersed in a nickel and / or cobalt alloy matrix. It is possible to obtain a cylinder lining material having a very thin particle-depleted layer and excellent wear resistance. Further, according to the present invention, a cylinder lining material having a particle-depleted layer having a desired thickness can be obtained.

It is the schematic diagram (a) and macro structure photograph (b) which show the structure of the cylinder lining material which concerns on this invention. It is a graph which shows the relationship between the thickness ratio with respect to the lining layer of a particle-deficient layer in a cylinder lining material, and the mass ratio with respect to tungsten carbide powder of tungsten boride powder. It is a SEM photograph of the lining layer part of the cylinder lining material concerning the present invention. It is a SEM photograph of the lining layer part of other cylinder lining materials concerning the present invention. It is a SEM photograph of the lining layer part of the cylinder lining material of a comparative example. It is a graph which shows the result of a sand abrasion test.

Hereinafter, modes for carrying out the invention will be described. The cylinder lining material for centrifugal casting according to the present invention has the following composition. That is, in mass%, tungsten boride + tungsten carbide (total amount): 30 to 45%, tungsten boride / tungsten carbide: 1 or less , tungsten boride: 5 to 20%, nickel + cobalt (total amount) : 35-50%, molybdenum: 1% or less, chromium: 10% or less, boron: 1-3%, silicon: 1-3%, manganese: 2% or less, iron: 5% or less, carbon: 1% or less Contains inevitable impurities. As a result, it is possible to obtain a cylinder lining material excellent in abrasion resistance in which tungsten carbide particles and tungsten boride particles are uniformly dispersed in nickel, cobalt, or an alloy base thereof, and a particle-depleted layer having a desired thickness is provided. it can.

  In the present invention, the tungsten carbide powder is hardly melted at the time of centrifugal casting and is dispersed in nickel, cobalt, or an alloy matrix thereof while maintaining the size and shape of the raw material. A spherical shape with less aggressiveness (galling, wear, damage) to the screw material is preferable. The average particle size of the tungsten carbide powder is preferably 6 to 12 μm. In general, tungsten carbide damages the mating material, and it is possible to solve the problem that the wettability with a matrix such as Ni group or Co group is bad and easy to break.

  On the other hand, tungsten boride powder is inferior in thermal stability to tungsten carbide powder and therefore decomposes (dissolves) to some extent during centrifugal casting, so the shape is not particularly specified. However, the particle size of the tungsten boride powder should be an average particle size of 3 to 12 μm, which is about the same as that of the tungsten carbide powder or 1/2 or more. Thereby, when a raw material is prepared, a uniform mixture of tungsten boride powder and tungsten carbide powder can be obtained.

  As described above, the total amount of the tungsten boride powder and the tungsten carbide powder is 30 to 45% by mass. The hardness of tungsten boride (36.3 GPa) is higher than the hardness of tungsten carbide (16.8 GPa), and tungsten boride powder can contribute to wear resistance as well as tungsten carbide powder. Therefore, by mixing the tungsten boride powder and the tungsten carbide powder, the characteristics of each of the tungsten boride and the tungsten carbide can be exhibited and desired wear resistance can be exhibited.

  However, if the total amount of tungsten boride powder and tungsten carbide powder is too large, sufficient fluidity of the tungsten boride or tungsten carbide powder (particles) can be maintained in the base of nickel, cobalt or their alloys. Therefore, normal centrifugal casting in which tungsten boride or tungsten carbide particles are uniformly dispersed cannot be performed.

  Further, as will be described below, when the amount of tungsten boride powder added exceeds a certain value, a good lining layer cannot be obtained. Therefore, the tungsten boride powder and tungsten carbide powder contained in the cylinder lining material are not suitable. It is good to include by mass ratio.

  Nickel or cobalt is a component that forms a nickel and / or cobalt alloy matrix in which the tungsten boride particles and tungsten carbide particles are dispersed, and the total mass is 35 to 50%. Thereby, a nickel and / or cobalt alloy matrix in which tungsten boride particles and tungsten carbide particles are uniformly dispersed can be formed. Usually, a nickel-based cylinder lining material can be used, but a nickel-cobalt alloy base is preferable in order to improve corrosion resistance and cavitation / erosion resistance.

  In addition, in order to improve the strength and hardness, molybdenum, chromium, and boron are added, and molybdenum: 1% or less, chromium: 10% or less, boron: 1-3%. Silicon, manganese, iron, and carbon may be silicon: 1 to 3%, manganese: 2% or less, iron: 5% or less, and carbon: 1% or less. In addition, since iron reduces corrosion resistance, it is good to make it 5% or less.

  The cylinder lining material has the above composition and can be manufactured by a known centrifugal casting method. However, in the centrifugal casting of the cylinder lining material, it is important to adjust the mass ratio of the tungsten carbide powder and the tungsten boride powder as described below. The tungsten boride powder is preferably adjusted to have a mass ratio of 0.14 to 1.00 with respect to the tungsten carbide powder.

  FIG. 1 shows the configuration of the cylinder lining material. Fig.1 (a) is a schematic diagram which shows the structure of this cylinder lining material, and FIG.1 (b) is a macro structure | tissue photograph. As shown in FIG. 1 (a), the cylinder lining material is formed on the inner peripheral surface of the cylinder body, is rich in nickel and / or cobalt alloy, and lacks tungsten boride particles and tungsten carbide particles. And a lining layer in which tungsten boride particles and tungsten carbide particles are dispersed in a nickel and / or cobalt alloy matrix.

As described above, in centrifugal casting of the cylinder lining material, it is important to adjust the mass ratio of the tungsten carbide powder and the tungsten boride powder. By adjusting the mass ratio, a thin thickness T _S of the particle depletion layer, for example, from those of 1 to 2 mm, to obtain those having a desired thickness T _S over a wide range up to those 10mm around thick it can. In the cylinder lining material, as shown in FIG. 2, the ratio of the particle depletion layer thickness T _{S to} the lining layer thickness T _L is the mass of the tungsten carbide powder with the mass WB of the tungsten boride powder WB. This is because the ratio to WC has a certain relationship. In other words, once the dimensions of the cylinder body to be cast and the amount of raw material input to the cylinder lining material are determined, the thickness of the cylinder lining material (T _M + T _L ) is determined, so adjust the WB / WC value. Thus, a cylinder lining material having a desired thickness T _S can be obtained. When the ratio of WB / WC is high, casting defects such as nests and porosity tend to occur during centrifugal casting. In particular, when WB / WC exceeds 1, it becomes difficult to obtain a good structure. T _S and T _L shown in FIG. 2 are average values. In FIG. 2, the ● mark indicates an invention example and the ■ mark indicates a comparative example. The composition of the cylinder lining material of the example shown in FIG.

  The cylinder lining material has a lining layer in which tungsten carbide particles and tungsten boride particles are uniformly dispersed in nickel, cobalt, or an alloy base thereof. 3 and 4 show scanning electron microscope (SEM) photographs of the lining layer portion of the cylinder lining material. FIG. 3 shows an example having the composition of WB / WC = 0.33 (10.0WB / 30.0WC) shown in Table 1. FIG. 4 shows an example having the composition of WB / WC = 1.00 (20.0WB / 20.0WC) shown in Table 1. For comparison, FIG. 5 shows an SEM photograph of a material having the composition of WB / WC = 0.00 (0.0WB / 40.0WC) shown in Table 1.

  As shown in FIGS. 3 and 4, in the lining layer of the cylinder lining material, tungsten carbide particles are dispersed in an island shape, and tungsten boride particles are finely dispersed over the entire surface of the nickel base. Is uniform. It can be seen that the tungsten carbide particles have an outer diameter of 1 to 15 μm and have a shape close to a sphere while maintaining the powder shape as the raw material.

  Further, according to FIGS. 3 to 5, as can be seen from the fact that the tungsten carbide particle interval becomes smaller as the tungsten carbide particle amount increases, in the lining layer of this cylinder lining material, the tungsten carbide particle interval is 8 It can be in the range of ~ 50 μm.

  On the other hand, the tungsten boride particles have an outer diameter of several μm or less and are considerably smaller than the powder of the raw material. When FIG. 3 and FIG. 4 are compared, it is observed that the tungsten boride particle density is higher in the case of the example of FIG. 4 having a larger amount of tungsten boride particles. However, in both FIG. 3 and FIG. 4, the dispersibility of the tungsten boride particles is good and the dispersion state is uniform.

  FIG. 6 shows the results of producing a cylinder lining material having the composition shown in Table 1 by centrifugal casting, producing a test piece composed of a lining layer from which a particle-deficient layer has been removed, and conducting a sand wear test and a hardness measurement test. Show. In FIG. 6, the wear volume is indicated by a bar graph, and the average value of Rockwell hardness is indicated by the mark ●. In addition, the test result of the comparative example was also displayed. (2) indicates the average value of the Rockwell hardness of the comparative example. The sand abrasion test was performed according to ASTM G65, and the wheel rotation speed was 200 rpm, the load was 130 N, and the test time was 10 min.

  As shown in FIG. 6, the wear volume is 0% (WB) when the added amount of tungsten boride powder (mass% of WB) is 5% (5.0WB / 35.0) to 20% (20.0WB / 20.0WC). /WC=0.0/40.0), and the wear volume decreases as the value of WB / WC increases from 5% to 13% (13.0WB / 27.0WC). However, it can be seen that when the mass% of WB is 13% to 20%, the wear volume increases as the value of WB / WC increases.

  On the other hand, the Rockwell hardness shows the same change state as the wear volume. That is, when the mass% of WB is 5% to 20%, the Rockwell hardness is 0% or more. From 5% to 13%, the larger the value of WB / WC, the greater the Rockwell hardness. Yes. However, it can be seen that when the mass% of WB is 13% to 20%, the Rockwell hardness decreases as the value of WB / WC increases.

  As described above, in the cylinder lining material according to the present invention, the tungsten boride particles and the tungsten carbide particles are uniformly dispersed in the nickel and / or cobalt alloy matrix, and the mass ratio of the tungsten boride powder to the tungsten carbide powder is WB / WC. Therefore, it has a lining layer in which the thickness, abrasion resistance and hardness of the particle-deficient layer are different. The mass ratio WB / WC can be 0.14 to 1.00, and the cylinder lining material preferably has a mass ratio WB / WC of 0.33 to 0.48.

Claims (5)

Mass%, tungsten boride + tungsten carbide (total amount): 30 to 45%, tungsten boride / tungsten carbide: 1 or less , tungsten boride: 5 to 20%, nickel + cobalt (total amount): 35 -50%, molybdenum: 1% or less, chromium: 10% or less, boron: 1-3%, silicon: 1-3%, manganese: 2% or less, iron: 5% or less, carbon: 1% or less and inevitable Cylinder lining material for centrifugal casting containing impurities.   2. The cylinder lining material for centrifugal casting according to claim 1, wherein tungsten carbide is a spherical powder having an average particle diameter of 6 to 12 [mu] m, and tungsten boride is a powder having an average particle diameter of 3 to 12 [mu] m. A lining layer provided on the inner peripheral surface of the cylinder body in which tungsten carbide particles and tungsten boride particles are dispersed in a nickel and / or cobalt alloy base, and formed on the inner peripheral surface of the lining layer. A centrifugal casting method for producing a cylinder lining material having a particle-deficient layer in which tungsten oxide particles are rare,
5% to 20% by weight of tungsten boride powder, the weight of tungsten carbide powder is more than the weight of tungsten boride powder, the total weight of tungsten carbide powder and tungsten boride powder is 45% or less, and the balance is nickel and / or cobalt alloy Using raw materials that are base forming components,
By adjusting the mass ratio of the tungsten carbide powder and the tungsten boride powder,
A centrifugal casting method for controlling the thickness of the particle-depleted layer.   4. The centrifugal casting method according to claim 3, wherein the tungsten boride powder has a mass ratio of 0.14 to 1.00 with respect to the tungsten carbide powder.   The centrifugal casting method according to claim 3 or 4, wherein a particle interval of tungsten carbide in the lining layer is 8 to 50 µm.

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