JP6091013B2 - Casting and manufacturing method thereof - Google Patents

Description

  The present invention relates to a casting and a manufacturing method thereof, and more particularly, to a casting having an ink marking on a casting surface cast using a mold whose contact surface with a molten metal is made of a refractory powder and a manufacturing method thereof.

  An individual identification mark made up of letters, numbers, figures and the like representing the date of manufacture and serial number may be attached to the casting (hereinafter referred to as “marking”). The marking on the casting is, for example, a method of casting a convex identification mark on the casting surface (casting surface) by engraving a mirror image of the identification mark on the casting skin (molding surface), or laser marking. There is a method of engraving a concave identification mark on a cast surface by an apparatus or an engraving machine or a smooth surface after machining the cast surface (Patent Document 2). Further, Patent Document 2 describes that marking is performed using ink on a machined surface of a casting (Mg casting product) cast using a mold.

JP 09-234543 A JP 2001-205423 A

  In the convex or concave marking methods described in Patent Documents 1 and 2, the casting has convex portions or concave portions on the surface that are not necessary for exhibiting the original function. For example, in the case of castings that are rotated at a high speed, such as impellers for turbochargers, it is not easy to design in consideration of the balance for suppressing whirling during rotation, and it is difficult to adjust the actual balance. There was inconvenience. Moreover, in the marking method by laser irradiation or engraving described in Patent Document 2, since the surface properties and the cast structure of the casting are changed and the mechanical properties are easily changed, the casting quality may be affected.

  In the marking method using the ink described in Patent Document 2, the casting does not have a convex portion or a concave portion which is not originally required on the surface. However, this marking method using ink targets a relatively smooth casting surface formed by transfer of a smooth surface of a mold or a smooth processed surface after machining, and has a rough cast surface. It was not a technique for casting or blasted cast skin.

  An object of the present invention relates to a marking technique using an ink for an as-cast or blasted cast skin in which a mold skin in contact with a molten metal is cast using a mold made of a refractory powder. It is an object of the present invention to provide a casting having an ink marking on such a casting surface and a method for producing the casting.

  In the process of developing a technique for performing marking using ink on a cast surface having a rough surface or a blasted cast surface, the present inventor has found that the ink bleeding in the marking is a temperature of the casting, particularly the casting surface. The present invention has been found to be strongly influenced by the temperature of

That is, the casting of the present invention has a barcode or two-dimensional code marking with ink on the casting surface having a surface roughness (Rz) of 5 μm or more and 20 μm or less .
The casting surface may be blasted.

In the casting of the present invention described above, the surface temperature of the casting skin formed by transferring the mold skin made of refractory powder is raised to 40 ° C. or more and 70 ° C. or less , and then the surface of the casting skin is marked with ink. It can produce by the manufacturing method which performs .
It is preferable to perform blasting of the casting surface before the temperature rise.
The marking can be performed by an ink jet printing apparatus.

  According to the casting manufacturing method of the present invention, ink marking can be performed on a casting skin formed by transferring a casting skin made of refractory powder. Therefore, it is not necessary to form a convex portion by marking or a concave portion for performing marking on the surface (casting surface) of the casting, and the surface properties and casting structure of the casting are not changed. Therefore, for example, in the case of a casting that is used by rotating at a high speed, such as an impeller for a supercharger, the effects of the present invention can be achieved, which can contribute to improving the efficiency of balance design and real balance adjustment.

It is a figure which shows the outline | summary of the manufacturing process of the casting which concerns on this invention. It is a conceptual diagram of the casting for demonstrating marking by an ink. It is a figure which shows the marking process including the process of heating up the surface of a casting surface using a hotplate. It is a figure which shows the marking process including the process of heating up the surface of a casting surface using a halogen heater.

Hereinafter, embodiments of a casting according to the present invention and a manufacturing method thereof will be described in detail with reference to the drawings as appropriate.
The casting according to the present invention (casting before marking with ink) can be produced, for example, by a precision casting process shown in FIG. Specifically, first, a vanishable model having an outer shape corresponding to the outer shape of a casting is produced using the extinguishing material (model production step). Subsequently, the surface of the extinguishing model is coated in multiple layers using a mold material containing refractory powder to form an outer shell, the extinguishing model is removed from within the outer shell, and the refractory powder constituting the outer shell is removed. A mold is produced by sintering (mold production process). Thereafter, a molten metal is poured into the mold to cast a casting (casting process). After cooling, the casting mold is removed, the casting is taken out, and the casting surface is cleaned (molding step). After the mold separation step, blasting may be performed to remove mold material remaining on the surface of the casting by blowing sand or the like. In such a manufacturing process, the shape of the casting is substantially equivalent to the shape of the cavity formed inside the mold by the vanishing model.

  A casting (cast before marking with ink) manufactured by a manufacturing method including the manufacturing process described above has a casting surface formed by transferring a mold skin (inner surface of an outer shell) made of refractory powder. Mold skin made of refractory powder because the mold skin (inner surface of the outer shell) has numerous irregularities due to large particles (coarse particles) contained in the refractory powder and voids present in the sintered structure. Compared to smooth skin, it is particularly rough. For this reason, the casting surface immediately after casting formed by transfer of the mold skin made of refractory powder (as-cast skin) is also roughly as rough as the mold skin. In addition, even when a more general blasting process is performed on an as-cast surface, surface smoothness such as polishing and grinding with removal of the surface structure or chemical conversion with surface elution is obtained. Therefore, the surface roughness cannot be particularly reduced. Therefore, in the marking method described in Patent Document 2, it is not possible to perform marking with ink on a cast surface having a rough surface or a blasted cast surface. The “cast skin formed by transferring the mold skin made of the refractory powder” of the present invention includes those subjected to the above blast treatment.

  A casting according to the present invention (a casting having an ink marking) is made of, for example, a casting surface of a casting (a casting before marking with an ink) manufactured by a manufacturing method including the manufacturing process described above, that is, a refractory powder. It is produced by marking with ink on the cast skin formed by the transfer of the mold skin. The casting material according to the present invention can be applied to a general lost wax precision casting method, Fe-based alloy, Ni-based alloy, Co-based alloy, Ti-based alloy, and heat resistance with enhanced heat resistance. It may be an alloy or a super heat resistant alloy. A conceptual diagram of a casting according to the present invention is shown in FIG. The casting 1 shown in FIG. 2 has a truncated cone and is composed of two planes and one inclined surface 11. The casting 1 is manufactured by a manufacturing method including the above-described manufacturing process, and the case where marking is performed with ink on one plane (marking surface 10) will be described. The marking surface 10 and the inclined surface 11 are cast skins formed by transferring the mold skin (inner surface of the outer shell) made of refractory powder, and may be subjected to blasting such as sand blasting. In addition, this invention is not limited to the casting 1 shown in FIG. 2 unless the main point is exceeded.

(Surface roughness of casting surface)
In the present invention, for the reasons described later, the maximum height roughness as a roughness parameter that can most accurately represent a surface texture that has infinite irregularities as in a cast surface and may have unsteady irregularities. (Rz) was selected. In addition, an arithmetic average roughness (Ra) was selected as a roughness parameter that can most accurately represent the level of surface texture having overall irregularities of the casting surface. In addition, the roughness parameter showing surface properties is prescribed | regulated to JIS-B0601: 2013.

  The Rz value is the distance in the direction of the vertical magnification between the highest peak and the lowest valley bottom in the reference length of the roughness curve, that is, the maximum value of the elevation difference between the scratches and irregularities on the measurement surface and the peaks and valleys . Therefore, the Rz value is strongly affected by the height of the peak and the depth of the valley, and if there is one abnormal scratch or unevenness on the roughness curve, that is, the measurement surface, that one abnormal scratch or unevenness is measured. It represents the surface texture of the surface. For example, if a casting having abnormal scratches or irregularities on the casting surface is supplied to the marking process, and ink is attached to the abnormal scratches or irregularities to form a part of the marking, the abnormal scratches or irregularities There is a high possibility that the outline of the marking corresponding to is greatly distorted. The surface texture of the casting surface including such abnormal scratches or irregularities that occur in an unsteady state can be appropriately expressed according to the maximum height roughness (Rz value).

  The Ra value is a value obtained by uniformly averaging the peak height and the valley depth in the reference length of the roughness curve, and thus can be said to be a value obtained by uniformly averaging the size of the unevenness on the measurement surface. Therefore, the Ra value is suitable when it is desired to accurately represent the level of the overall surface roughness (surface properties) of the casting surface. However, if you want to accurately represent the surface properties that have infinite irregularities like cast skin and may have irregular irregularities, the influence of the height and valley depth of each irregularity will be mitigated. In the present invention, the Rz value is more appropriate than the Ra value.

  In order to confirm the surface roughness (Rz value and Ra value) of the casting surface of the casting 1, before the marking with the ink, 30 castings 1 having the same component composition are arbitrarily selected, and the marking surface 10 and the inclined surface thereof are selected. 11 surface roughness (Rz and Ra) were measured. In the measurement, after sandblasting, substantially the same area on the surface of each of the marking surface 10 and the slope 11 was measured.

  Table 1 shows an average value, a maximum value, and a minimum value of roughness measurement values on the marking surface 10 of 30 castings 1. The casting targeted by the present invention may be considered to have a casting surface formed by transfer of a mold skin made of a refractory powder generally used in precision casting methods such as the lost wax method. Except in the case of castings that require rough surface properties, the castings according to the present invention have a surface roughness equivalent to the surface roughness of the marking surface 10 shown in Table 1, that is, slightly larger, slightly smaller, or a surface roughness of a certain degree. You may think that it has. Therefore, the casting surface having the marking with the casting ink in the present invention may have an Rz value of 20 μm or less and an Ra value of 3 μm or less. Further, it is a casting having a surface that does not have smoothness as at least by the above-described polishing, grinding, and chemical conversion treatment, that is, a casting having a surface roughness with an Rz value of 5 μm or more and an Ra value of 1 μm or more. If it exists, there exists an effect of this invention especially and it is useful.

  When the Rz value of the casting surface exceeds 20 μm, the distance from the top of the convex portion of the casting surface to the bottom of the concave portion (the depth of the valley from the surface of the casting surface) increases, so when reading the marking The range of focus (depth of field) is increased. Therefore, when reading the marking with ink, it becomes difficult to focus due to the wide depth of field of the marking, and the reading accuracy of the marking may decrease. Therefore, the Rz value of the casting surface is preferably 15 μm or less. Further, it is preferable that the Rz value and Ra value of the casting surface become smaller and the surface of the casting surface becomes smoother. It is easier to have markings with ink on the casting surface and to read the markings on the casting surface. become.

  The marking with ink targeted by the present invention may be a barcode or a two-dimensional code. Bar codes and two-dimensional codes are figures (graphic symbols) in which various types of information such as the date of manufacture and serial number are coded based on a predetermined rule. Available. A bar code is a one-dimensional code having information in one direction, and the printing area required for identification can be reduced as compared with a method in which predetermined information such as a manufacturing date and a manufacturing number is printed one character at a time. . The two-dimensional code is preferable because it has information in two directions, horizontal and vertical, and can have more information and can have a smaller printing area than a bar code that is a one-dimensional code. The two-dimensional code may be a matrix type (matrix code) in which small squares are arranged vertically and horizontally, or a stack type (stack code) in which a plurality of bar codes are stacked vertically.

  The casting according to the present invention (casting with ink marking) does not substantially change the surface shape or casting structure of the casting, for example, using an ink jet type or stamp type printing device and before casting. It can be produced by spraying or transferring ink onto the surface of the casting surface. Preferably, it is an ink jet type printing apparatus, and can be printed in a non-contact manner on the casting surface, so that it is hardly affected by the surface shape. Moreover, the ink used for marking on the casting surface has, for example, excellent resistance to industrial cutting oils and hydrocarbon-based cleaning liquids, and is suitable for industrial inkjet printers that dry quickly and have high versatility. It is preferable to use ink. For example, an alcohol-resistant ink having a boiling point of about 80 ° C. and methyl ethyl ketone (MEK) as a main solvent can be used.

  An important feature of the manufacturing method according to the present invention is that the surface temperature of the casting skin formed by the transfer of the mold skin made of refractory powder is raised to 40 ° C. or higher when marking with ink that enables reading by a reader. After the heating, marking is performed on the surface of the casting surface using ink. In this case, it is preferable to perform blasting of the casting surface before the temperature rise. The blast treatment can remove mold pieces, casting burr pieces, dust such as sand, moisture, oil, and the like that easily adhere to the casting and inhibit the wetting and spreading of ink on the casting surface. Thereby, compared with the casting surface which does not perform a blast process, the casting surface of a casting can have the surface property which is easy to perform marking by an ink.

  When marking with ink, if the surface of the casting surface is at room temperature (about 25 ° C.), the liquid ink adhering to the casting surface may spread and spread excessively on the casting surface. Marking with bleeding due to excessive wetting and spreading of ink cannot be accurately identified as predetermined information even if it can be read by a reader (reader) after the ink has dried on the casting surface. is there. When the surface temperature of the casting surface is 40 ° C. or higher as defined in the present invention, it is possible to accelerate the drying of the ink adhering to the casting surface, thereby suppressing the ink from excessively spreading and spreading on the casting surface. Can do. Thereby, the marking with a clear outline can be fixed on the casting surface. Therefore, the identification information possessed by the marking can be obtained accurately by reading and analyzing the marking with a reader.

In addition, when using the alcohol-resistant ink whose main solvent is methyl ethyl ketone (MEK) having a boiling point of about 80 ° C. as described above, when the surface temperature of the casting surface exceeds 60 ° C., the ink adhering to the casting surface Drying may be particularly quick. Further, if the temperature exceeds 70 ° C., the ink is dried too quickly, so that the ink spreading on the casting surface may stop before forming a significant contour as a marking. In such a case, it is preferable to raise the surface temperature of the casting surface to 70 ° C. or less. Thereby, wetting and spreading of the ink on the casting surface can be continued to such an extent that a significant contour as a marking is formed. Incidentally, the upper limit of the temperature increase (above 70 ° C.) is originally determined to suit the conditions such as the liquid component contained in the ink (in particular, boiling point) and the casting surface of the surface properties (particularly surface roughness R _Z value) However, the temperature is preferably 65 ° C., more preferably 60 ° C., from the viewpoint of availability of ink, production efficiency, and stability of marking quality.

  Moreover, when raising the surface temperature of a casting surface to 40 degreeC or more, the casting may be heated whole and the casting surface which performs marking may be partially heated. The heating method may be appropriately selected from direct heating, conduction heating, infrared heating, far infrared heating, high frequency heating, microwave heating, and the like. The heating device is, for example, a burner, hot air or hot air spraying device, electric heater, hot plate, oven, halogen heater, carbon heater, ceramic heater, infrared or far infrared lamp, heating device using high frequency or microwave, etc. Therefore, it may be selected as appropriate. In the present invention, it is recommended to use hot plates, heaters, and lamps because of the advantages such as simple apparatus configuration, easy handling, and easy continuous operation.

  Next, a process (marking step) for marking the marking surface 10 of the casting 1 shown in FIG. 2 using ink will be described with reference to the drawings as appropriate.

The marking step shown in FIG. 3 includes a step of partially heating the casting 1 using the hot plate 20 and raising the temperature of the surface of the casting skin including the region where marking is performed.
In the heating step shown in FIG. 3A, the casting 1 is placed on the hot plate 20 so that the marking surface 10 faces the heating surface 21 of the hot plate 20. When the hot plate 20 is started, the heating surface 21 generates heat, and the heat is conducted or radiated from the heating surface 21 to reach the casting 1, and the temperature of the region including the marking surface 10 rises. Eventually, the surface temperature of the marking surface 10 reaches a predetermined temperature (hereinafter referred to as “temperature T1”).

  In the marking process shown in FIG. 3B following the heating process using the hot plate 20, the casting 1 is arranged so that the marking surface 10 faces the print head 31 of the printing apparatus 30. During this movement, the surface temperature of the marking surface 10 gradually decreases. Immediately after confirming that the surface temperature of the marking surface 10 has reached a predetermined temperature for printing the marking (hereinafter referred to as “temperature T2”) using a contact thermometer, a radiation thermometer, etc. The apparatus 30 is started, and marking with ink is performed on the marking surface 10 which is a casting surface. The ink adhering to the marking surface 10 evaporates the liquid component and fixes the color component according to the surface temperature of the marking surface 10, and a marking is formed on the marking surface 10 with the color component of the ink. At this time, the degree of bleeding due to spreading of ink varies depending on the time required for evaporation, that is, the temperature T2 of the surface of the marking surface 10.

  The step of raising the temperature of the surface of the casting surface including the region to be marked may be a heating step using the halogen heater 25 instead of the heating step using the hot plate 20 shown in FIG. FIG. 4 shows a marking process including a heating process using the halogen heater 25. In this step, the casting 1 is arranged so that the marking surface 10 faces the print head 31 of the printing apparatus 30 as in the marking step shown in FIG. Moreover, the irradiation part 26 of the halogen heater 25 is arranged so that the irradiation from the halogen heater 25 is performed from above the marking part 2 of the casting 1. At this time, if the marking part 2 of the casting 1 is irradiated with heat as vertically as possible, the thermal efficiency is good.

  When the halogen heater 25 is started, heat using infrared light as a heat source is irradiated from the irradiation unit 26 to the region including the marking unit 2 of the casting 1, and in the region including the marking unit 2 on the marking surface 10 which is a casting surface. The temperature rises. Eventually, the surface temperature of the region including the marking portion 2 reaches a predetermined temperature T2. Immediately after confirming that the temperature T2 has been reached, the printing apparatus 30 is started immediately in the same manner as in the marking step described above, and marking is performed on the marking surface 10 that is the casting surface with ink. Note that heating devices that use infrared light as a heat source, such as halogen heaters, can be heated in a relatively short time because of their high thermal efficiency, and the device is small and easy to handle. It is suitable for raising the temperature of the surface.

  In the subsequent inspection process shown in FIG. 3C, in addition to the visual inspection of the marking, a reading inspection of the marking by the reader (reading device) 40 is performed. The casting 1 is arranged so that the marking portion 2 on the marking surface 10 faces the imaging lens 41 of the reader 40, and the reader 40 is started to read the marking printed on the marking portion 2. In the visual inspection, in order to determine the sharpness of the marking, the degree of ink bleeding (bleeding level) is confirmed. In the reading inspection, whether or not the marking can be read by the reader, the reading sensitivity level, and the reproducibility of the significant identification information of the marking are confirmed. Depending on the reading sensitivity level, the reader reads and analyzes the marking, recognizes the significant identification information of the marking, and processes the time required to output or display the recognition information, the accuracy of reading, etc. Judgment. Further, the marking design information is compared with the information read and displayed by the reader, and if both match, it is determined that the identification information is reproducible.

  As described above, following the manufacturing process of the casting shown in FIG. 1 (casting before marking with ink), the heating step shown in FIG. 3A or 4, the marking step shown in FIG. 3B, The surface temperature of the marking surface 10 is 40 ° C. or higher with respect to the marking surface 10 which is a casting surface formed by transfer of the mold skin made of refractory powder by the manufacturing process including the inspection process shown in FIG. The casting 1 which has marking with the ink on the marking surface 10 which is a casting surface by the manufacturing method which performs marking using an ink after temperature rising can be produced.

  Next, a marking test was performed in which marking was actually printed on the casting surface using ink. The marking was a matrix type two-dimensional code (matrix code) having a length of 6 mm and a width of 6 mm. In the marking test, whether or not the marking surface can be marked, whether or not the marking outline is clear, whether or not the marking can be read using a reader (reading device), and the reliability of the reading information (reading) (Accuracy) was investigated. Specifically, using the casting 1 when the surface roughness (Rz value and Ra value) of the casting surface shown in Table 1 was confirmed, the same method as the heating step and the marking step using the halogen heater 25 described above. Thus, marking was performed on the marking surface 10 which is the casting surface of the casting 1 using ink. The distance between the marking surface 10 of the casting 1 and the print head 31 of the printing apparatus 30 is about 30 mm. Subsequently, the marking by the ink on the marking surface 10 of the casting 1 was investigated by the same method as the inspection step described above.

  In the marking test, a 75 W halogen heater was used as the heating device. The printing apparatus used was an industrial inkjet printer (model 7900, alcohol-resistant black ink 1075 diluted with alcohol-resistant solvent 1575) manufactured by Linx Printing Technologies plc. The black ink contains at least a liquid component containing methyl ethyl ketone having a boiling point of about 80 ° C. and a black chromium complex dye. The reader is a COGNEX barcode reader (DataMan100Q-ECC200, 1 / 3-inch CMOS w / Global shutter (752 × 480 resolution, 3 position adjustable lens (6.2 mm, F: 5 aperture) with mm 40 mm, 40 mm, 40 mm, 40 mm, 40 mm, 40 mm, 40 mm) distances) was used.

In the marking test, the target value (temperature T2) of the surface temperature of the casting surface on which the marking is printed was set to six conditions of room temperature (25 ° C.), 35 ° C., 40 ° C., 50 ° C., 60 ° C., and 70 ° C. The irradiation time when the halogen heater 25 is used for the heating device is 5 seconds and 10 seconds in addition to the condition of about 3 seconds for the surface temperature (temperature T2) of the region including the marking portion 2 to reach about 50 ° C. The conditions were also confirmed. In addition, temperature T2 was about 25 degreeC without irradiation (irradiation time 0 second).
The results of the marking test are shown in Table 2.

  As shown in Table 1, in test numbers 1, 2, and 7 where the surface temperature T2 of the marking surface 10 of the casting 1 is 35 ° C. or less, the marking ink has a large blur and the contour is not clear. Could not be read. Further, in test number 10 where the temperature T2 is 75 ° C., the ink bleeding of the marking was small (almost), but the ink liquid spreads out before the ink spreads and forms the marking. there were. In this case, the reading sensitivity by the reader is low, and some of the markings may not be read. In test numbers 3 to 6, 8, and 9, the marking ink bleeding was small and the contour was clear, the marking could be read by a reader, and the reproducibility of the identification information was not particularly problematic.

  From the above, when marking is performed on the surface of the cast skin formed by transferring the mold skin made of refractory powder using ink, at least the temperature T2 of the cast skin surface to be marked exceeds 35 ° C. and 40 ° C. It was confirmed that the temperature should be increased to the above. Even in this case, a difference was recognized in the reading sensitivity level of the marking by the reader. The reading sensitivity level was the best when the temperature T2 was 50 ° C. (test numbers 4 and 8) and 60 ° C. (test numbers 5 and 9). Next, the reading sensitivity level was good when the temperature T2 indicated as “medium to large” in Table 2 was 40 ° C. (test number 3). The reading sensitivity level when the temperature T2 indicated as “small to medium” in Table 2 is 70 ° C. (test number 6) was relatively small. Accordingly, it has been found that it is preferable to set the temperature T2 to less than 70 ° C. when importance is attached to the reading efficiency of the marking.

1. Casting, 2. Marking part, 10. 10. marking surface Slope, 20. Hot plate, 21. Heating surface, 25. Halogen heater, 26. Irradiation unit, 30. Printing apparatus, 31. Print head, 40. Leader, 41. Imaging lens

Claims (4)

A casting having a barcode or a two-dimensional code marking with ink on a casting surface having a surface roughness (Rz) of 5 μm or more and 20 μm or less.   A method for producing a casting, wherein the surface temperature of a casting skin formed by transfer of a mold skin made of a refractory powder is heated to 40 ° C. or more and 70 ° C. or less, and then the surface of the casting skin is marked using ink. The casting manufacturing method according to claim 2 , wherein the casting surface is blasted before the temperature rise. The casting manufacturing method according to claim 3 , wherein the marking is performed by an ink jet printing apparatus.

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