JP4296409B2 - Mold quality control method for casting mold - Google Patents

Description

  The present invention relates to a method for controlling the quality of a coating mold (coating agent) applied to a casting mold.

  In mold casting, coating is applied to the surface of the mold, especially the molding part that forms cavities, for the purpose of preventing the mold from damaging, ensuring hot water resistance, and promoting directional solidification. . As the coating mold, ceramic fine particles are generally used and are usually coated in multiple layers so as to have a predetermined film thickness. In this case, the service life of the coating mold is several hundred shots. Therefore, conventionally, the coating mold is re-applied with an appropriate number of shots (about 500 shots) before the coating mold reaches the service life.

  By the way, even if it is called coating quality, the contents vary widely such as film thickness, air permeability, heat retention, strength, etc. If these are inappropriate, it is difficult to ensure the desired mold life and casting quality. become. More specifically, if the film thickness is thin, mold may be melted at an early stage, if the air permeability and heat retention are insufficient, there will be thinning due to poor water circulation, and if heat retention is high, it will be closed by eliminating directional solidification. If the strength of the nest is insufficient, the mold may be damaged due to early peeling or poor hot water. In addition, although coating application | coating of what is called a coating type with respect to a metal mold | die generally relies on the manual operation | work by an operator, it is performing the automatic application | coating by an automatic coating apparatus in one part (for example, refer patent document 1) .

JP-A-4-309434

  However, according to the conventional coating quality control method, the coating quality such as film thickness, air permeability, heat retention, strength, etc. is only ascertained by a prior laboratory test. The quality of the finished product could not be grasped without actually casting it. In particular, when performing mold application manually, there is a large variation in the quality of the mold, and it often happens that the paint must be re-applied (re-executed) prior to regular application. It was. In addition, in the thing of patent document 1, when apply | coating a coating mold automatically to a casting metal mold | die, a film thickness is measured by a film thickness sensor and the nozzle for spraying a coating mold is controlled based on the measurement result. However, even in this case, the coating quality other than the film thickness (air permeability, heat retention, strength, etc.) cannot be grasped. On the other hand, the coating work is generally performed outside the casting process, and in order to re-execute the coating process, it is necessary to remove the mold from the casting machine and move it out of the process. For this reason, as described above, when a situation that requires re-working of the coating mold frequently occurs, a reduction in the operating rate of casting and a reduction in productivity become unavoidable, and countermeasures are urgently required. It was.

  The present invention has been made in view of the above-described conventional problems, and the problem is that the coating quality can be accurately grasped every time the casting is applied to the casting mold, Accordingly, it is an object of the present invention to provide a coating quality control method that greatly contributes to improvement of casting quality and productivity.

  In order to solve the above-described problems, the present invention provides a method in which another piece is detachably embedded around a molding part of a casting mold and a coating die is applied to the molding part under the same conditions as those for the molding part. A coating die is also applied to the piece, and then the separate piece is separated from the casting mold, the coating die applied to the separate piece is inspected, and applied to the molding portion based on the inspection result. It is characterized by determining the quality of the coating mold quality. In the coating quality control method performed in this way, the coating quality can be accurately grasped with another piece as an inspection object, so that a mold with poor coating quality is not put into the casting process.

In the present invention, it is desirable that the above-described inspection of the coating mold includes an inspection of film thickness, air permeability, heat retention and strength, thereby improving the reliability of the quality inspection of the coating mold.
Further, the separate piece may be fitted into a hole provided in advance in the mold and bolted, and in this case, the separate piece can be easily attached and detached.

  According to the mold quality control method for a casting mold according to the present invention, the mold quality can be accurately grasped every time the mold is applied, so that a mold with poor coating quality is put into the casting process. This has the effect of greatly contributing to the improvement of productivity as well as the improvement of casting quality.

  Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

  FIG. 1 shows an embodiment in which the coating quality control method according to the present invention is applied to a low pressure casting mold. In the figure, a low-pressure casting mold denoted by reference numeral 1 includes a lower mold 2 having a fixed position and an upper mold 3 disposed so as to be able to approach and separate from the lower mold 2. Molded portions 2a and 3a are formed on the opposing surfaces of the lower mold 2 and the upper mold 3, respectively, and the cavity 4 is defined by both molded portions 2a and 3a in the illustrated closed state. . Further, a gate 5 is set at the bottom of the lower mold 2, and a flow path 7 in the stalk 6 extending from the lower surface of the lower mold 2 to a molten metal holding furnace (not shown) is connected to the gate 5. ing.

  During casting, the molten metal in the molten metal holding furnace is injected into the cavity 4 from the flow path 7 in the stalk 6 through the gate 5 of the lower mold 2 at a low pressure. The molten metal injected into the cavity 4 is sequentially solidified from the upper mold 3 side to the lower mold 2 side, and the inside of the pouring gate 5 becomes the final solidified region by this directional solidification. Then, when the pressurization in the molten metal holding furnace is released at the timing when the solidification progresses to the upper tapered portion of the gate portion 5, the unsolidified molten metal in the gate portion 5 is brought together with the molten metal in the flow path 7 of the stalk 6. While falling into the molten metal holding furnace, the casting is released from the lower mold 2 in accordance with the upward movement (opening of the mold) of the upper mold 3.

  Here, a coating mold (coating agent) 10 is applied to the molding part 2 a of the lower mold 2 and the molding part 3 a of the upper mold 3. The coating mold 10 is made of ceramic fine particles as in the prior art, and the coating (coating process) is performed outside the casting process before assembling the mold 1 to the casting machine. By applying the coating mold 10 to each molding part 2a, 3a to an appropriate thickness, melting of the lower mold 2 or the upper mold 3 is suppressed during casting, thereby extending the mold life. In addition, the appropriate air permeability, heat retaining property and strength of the coating mold 10 improve the hot water circulation during casting and promote the directional solidification, thereby suppressing the occurrence of the lack of thickness and shrinkage in the cast product. .

  Accordingly, different pieces 11 and 12 are embedded in advance around the molding portion 2a of the lower mold 2 and around the molding portion 3a of the upper mold 3, and the different pieces 11 and 12 are also coated. A mold 10 'is applied. In the present embodiment, each of the separate pieces 11 and 12 is a corner portion of the upper mold 3 (lower mold 2) as shown in FIG. 2 as representative of the upper mold 3 side, and interferes with the molded portions 2a and 3a. It fits into the hole 13 formed in the part not to be used, and is fixed by using a plurality (two in this case) of bolts 14. Each of the separate pieces 11 and 12 is formed in the shape of a rectangular plate from the same material as that of the mold 1 and has a size of 50 mm in length and 70 mm in width as an example. Further, the thickness is slightly smaller than the depth of the hole 13 so that the coating mold 10 ′ on the separate pieces 11 and 12 does not protrude from the mating surface of the lower mold 2 and the upper mold 3. It has become.

  The separate pieces 11 and 12 are used for quality control of the coating mold 10 applied to the mold 1, and the coating mold 10 ′ thereon is applied when the coating mold 10 is applied to the molding portions 2 a and 3 a. It is applied under the same conditions. However, in the present embodiment, since the coating mold construction is performed manually by the operator, strictly speaking, it is not exactly the same condition, but it is different from the coating construction for the molding parts 2a, 3a continuously. Since the coating is applied to the pieces 11 and 12, it can be said that the conditions are substantially the same.

  Hereinafter, the coating quality control method performed using the separate pieces 11 and 12 will be described with reference to FIG. Here, for convenience of explanation, a management method for the upper mold 3 will be described, but not only for the lower mold 2 described above, but also for various molds that require coating. It goes without saying that the same management method is adopted.

  When applying the coating mold, first, another piece 12 is fitted into the hole 12 of the upper mold 3 and fixed using the bolt 14 (S1). Next, at the same time as applying the coating to the molding part 3a of the upper mold 3, applying to the another piece 12 (S2). At the time of this coating work, the operator pays attention not to change the spraying conditions between the case of the molding part 3a and the case of the separate piece 12, and the coating work is performed under substantially the same conditions. Next, after the coating molds 10 and 10 'are dried, the bolts 14 are loosened and the other pieces 12 are removed from the upper mold 3 (S3). Then, about this another piece 12, the film thickness t of the coating film 10 ', the air permeability V, the heat retention H, and the strength S are measured (inspected) (S4). In the present invention, these measuring methods are arbitrary, but it is desirable to adopt a method that can be easily carried out in the field.

  In the next step S5, if each of the measurement results is equal to or greater than the set value R (t, V, H, S ≧ R), the quality of the coating mold 10 applied to the molded part 3a is good. It judges that there exists, and attaches the said another piece 12 to the upper mold | type 3 again (S6), complete | finishes coating quality control, and throws the inspected upper mold | type 3 into a casting process. On the other hand, if any of the measurement results in step S5 is less than the set value R (t, V, H, S <R), it is determined that the coating mold 10 is unacceptable. The coating molds 10 and 10 'are removed from the upper mold 3 and the separate piece 12 using, for example, shot blasting (S7). Then, the separate piece 12 is attached to the upper mold 3 again (S1), and thereafter the steps S2 to S5 are repeated to reinspect the coating quality. The step S6 may be omitted. In this case, the upper die 3 is put into the casting process with the inside of the hole 13 being emptied. However, since the coating mold 10 'on the separate piece 12 is an important index for seeing the change of the coating mold 10 with time, in order to manage the coating quality, It is desirable to put the mold 3 into the casting process.

  In this way, for the casting process, only molds that have passed the coating quality are input. Therefore, when casting using such molds, the casting quality is poor. Therefore, the shortening of the service life of the mold or the deterioration of the casting quality is remarkably suppressed. Therefore, it is sufficient to perform the re-working of the coating mold on a regular basis, and accordingly, the operating rate of casting is improved, and as a result, productivity is improved. In addition, since the variation in coating quality can be reduced, the frequency of re-working the coating mold can also be reduced (500 → 1000 shots). Especially in this embodiment, since the film thickness t, the air permeability V, the heat retention H, and the strength S are inspected to determine the quality of the coating mold quality, the reliability of the coating mold quality inspection is extremely high. It becomes.

In the above embodiment, the separate pieces 11 and 12 are fitted into the holes 13 provided in the lower mold 2 and the upper mold 3 constituting the mold 1 and fixed using the bolts 14. The attachment method of the separate pieces 11 and 12 with respect to the metal mold | die 1 is arbitrary, and the other method which does not depend on a volt | bolt is employable.
The type of casting mold to which the present invention is applied is arbitrary, and can be applied to various molds for suction casting, gravity casting and the like other than the above-described low pressure casting mold.

It is sectional drawing which shows embodiment at the time of applying the coating-type quality control method which concerns on this invention to the metal mold | die for low pressure casting. It is a top view which shows the installation aspect of another piece with respect to a metal mold | die. It is a flowchart which shows the implementation procedure of this coating type quality control method.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Mold 2 Lower mold 3 Upper mold 2a, 3a Molding part 4 Cavity 10, 10 'Coating mold 11,12 Separate piece 13 Hole 14 Bolt

Claims (3)

When another part is removably embedded around the molding part of the casting mold and the coating mold is applied to the molding part, the coating part is applied to the another piece under the same conditions as those for the molding part. Separating the separate piece from the casting mold, inspecting the coating mold applied to the separate piece, and determining whether the quality of the coating mold applied to the molded part is good or bad based on the inspection result. A coating quality control method for a casting mold. The coating quality control method for a casting mold according to claim 1, wherein the inspection of the coating mold includes an inspection of film thickness, air permeability, heat retention and strength. The casting quality control method for a casting mold according to claim 1 or 2, wherein another piece is fixed by fitting into a hole provided in advance in the mold.

Images