JP7130182B2 - Mold repair method and mold - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for repairing a mold and a mold, and more particularly to regeneration of a mold surface having irregularities in the mold.

For example, Patent Literature 1 discloses a press die surface repair method for repairing a damaged portion on the flat surface of the die. Specifically, first, a processing hole is formed in the flat surface of the press die by punching a concave damaged portion on the flat surface of the press die over a wider area. Next, the machined hole is closed by driving a driving member into the machined hole. Then, the flat surface of the mold is regenerated by grinding the driving member (protruding portion) protruding from the flat surface with a grinder or the like. In addition, although it does not relate to a method for repairing a mold, Patent Document 2 discloses that a high-precision mold is obtained by making the direction of the cutting resistance with respect to the feed direction of the end mill constant and equalizing the cutting resistance when the end mill is reciprocated. A method of cutting a mold to create a more flexible mold is disclosed.

JP 2017-47447 A JP-A-11-347823

In recent years, molds made in Japan are often used in overseas factories, including those in developing countries. If damage such as scratches occurs on the surface of the mold due to use on site, it is not realistic to send it to Japan for repair from the viewpoint of cost and speed, and it is usually repaired quickly on site. Must. However, when repairing using a processing machine that exists locally, the molding surface of the mold cannot be repaired with high accuracy, even though the end mill with the same diameter as the one used when the new mold was made is used. It happened. This problem is particularly conspicuous in a molded article whose surface is decorated with a glittering pattern such as a diamond block pattern or a honeycomb pattern, and the glowing pattern may become visually obscured in the repaired area.

SUMMARY OF THE INVENTION The present invention has been made in view of such circumstances, and an object of the present invention is to accurately repair an uneven molding surface of a mold.

In order to solve this problem, the first invention provides a mold repair method having first and second steps. In the first step, a repair material is used to fill the damaged portion on the uneven molding surface of the mold. In the second step, the surface raised by the repair material is cut with a second end mill having a smaller diameter than the first end mill used to newly create the mold, thereby forming an uneven molding surface. to play.

Here, in the first invention, the second step comprises detecting rotational runout of the spindle to which the second end mill is attached, and selecting the diameter of the second end mill according to the detected rotational runout. and the step of Alternatively, the second step includes a step of detecting rotational run-out of the spindle to which the second end mill is attached; and allowing the use of At that time, if the detected rotational run-out is greater than a predetermined threshold, it may further include a step of disallowing the use of the second end mill. Further, in the first invention, the uneven molding surface preferably has an uneven pattern for decorating the surface of the molded article with a glitter pattern.

A second invention provides a mold having an uneven molding surface. The mold has a non-repaired area where the molding surface is not repaired and a repaired area including a portion where damage on the molding surface is repaired. Here, the cutter path shape on the surface of the repair area is smaller than the cutter path shape on the surface of the non-repair area.

According to the first invention, when repairing a mold, a second end mill having a diameter smaller than that of the first end mill used when creating a new mold is used. In general, as the run-out of the spindle to which the end mill is attached increases, the apparent diameter of the end mill also increases. can reduce the decline in As a result, even if a processing machine with greater rotational runout is used during repair than during new production, excessive grinding of the surface can be suppressed, so that the uneven molding surface can be repaired with high accuracy.

Moreover, according to the second invention, it is possible to verify whether or not the mold has been repaired by the repair method according to the first invention.

External view of the mold Cross-sectional view of a mold with a damaged part Diagram showing the process of filling the damaged area with repair material Diagram showing the cutting process with an end mill Explanatory diagram for repairing using an end mill with the same diameter as when creating a new mold Explanatory drawing when repairing using an end mill with a smaller diameter than when creating a new mold Enlarged photo showing the condition of the molding surface in the mold

FIG. 1 is an external view of a mold according to this embodiment. This mold 1 is used to mold a plastic molded product or the like whose surface is decorated with a glittering pattern such as a diamond block pattern or a honeycomb pattern. On the molding surface 1a of the mold 1, an uneven pattern is formed by reversing the unevenness on the side of the molded product that makes the glow pattern appear.

When the mold 1 is attached to or removed from the press device, or when the removed mold 1 is transported, if an object accidentally hits the mold 1, unevenness will occur as shown in FIG. The molding surface 1a of is damaged, resulting in a partially depressed damaged portion 1b. In this case, it is necessary to promptly repair the damaged mold 1 on site so as not to delay the production line of the factory.

As repair work for the mold 1, first, as shown in FIG. As a result, the surface on which the repair material 2 is piled up becomes a state of protruding from the surroundings.

Next, as shown in FIG. 4, the surface raised by the repair material 2 is cut with an end mill 3 to make the raised surface flush with the surroundings. Thereby, the molding surface 1b is regenerated. Here, the diameter R1 of the end mill 3 used when repairing the mold 1 is smaller than the diameter R2 of the end mill used when newly creating this mold 1 .

As shown in FIG. 5, a case is considered in which the diameter of the end mill used at the time of making a new mold 1 is R2, and the repair is performed using an end mill 3' having the same diameter. Since the main shaft of the processing machine to which the end mill 3' is attached has rotational runout α, the apparent diameter of the end mill 3' during rotation is R2+α. When the mold 1 is repaired using a processing machine with greater rotational runout than when it was newly created, a difference of α occurs in the rotational runout in the worst case. As a result, in the worst case, the profile of the molding surface 1a formed by a ball mill with a diameter of R2 at the time of new creation is cut by a ball mill with a larger diameter (R2 + α), and the area A of the molding surface 1b is excessively cut. It will be cut. Such over-cutting is not preferable because it is clearly reflected in the glitter pattern of the molded product to which the concave-convex pattern of the molding surface 1b is transferred, resulting in poor appearance.

On the other hand, as shown in FIG. 6, consider the case where the diameter of the end mill used when creating a new mold 1 is R2, and the repair is performed using an end mill 3 with a smaller diameter R1. . In this case, the apparent diameter of the end mill 3 becomes R1+α due to rotational runout of the spindle, but if this is R2 or less, the problem of overcutting described above does not occur. That is, overcutting of the molding surface 2 can be effectively suppressed by using an end mill 3 having a smaller diameter than that used when the mold 1 is newly prepared, in anticipation of the rotational run-out α.

The following two measures are conceivable as specific countermeasures for repairing the mold 1 . First, the diameter of the end mill 3 is selected according to the rotational run-out α of the spindle to which the end mill 3 is attached after measuring the rotational run-out α using a measuring instrument. For example, the larger the rotational runout α, the smaller the diameter of the end mill 3 is selected.

Secondly, when the rotational run-out α measured by the measuring instrument is equal to or less than a predetermined threshold value (R2-R1), the use of the end mill 3 having a diameter of R1 is permitted, which is the predetermined threshold value (R2-R1 ), the use of the end mill 3 with a diameter R1 is not permitted (use is prohibited).

FIG. 7 is an enlarged photograph showing the state of the molding surface 1a of the mold 1. As shown in FIG. In general, when the molding surface 1a is machined by cutting with an end mill, a spiral cutting mark (cutter path shape) derived from the cutter path is generated. As a characteristic of this, the smaller the diameter of the end mill, the smaller the shape of the cutter path and the finer the surface roughness of the molding surface 1a.

From this characteristic, by comparing the states of both the non-repaired area and the repaired area on the molding surface 1a, it is possible to determine whether the mold has been repaired by the repair method described above. The non-repaired area is an area in which the molding surface 1a is not repaired, and the repaired area is an area including a repaired portion (including the periphery of the damaged portion) on the molding surface 1a. Specifically, the shape of the cutter path generated on the surface of the repaired area is smaller than the shape of the cutter path generated on the surface of the non-repaired area. It can be determined that the mold has been repaired. In addition, since the surface roughness in the repaired region is finer than the surface roughness in the non-repaired region, it can be determined that the mold has been repaired by this repair method based on the appearance of such a state. .

As described above, according to the present embodiment, when repairing the mold 1, the end mill 3 having a diameter smaller than that used when the mold 1 was newly created is used. In general, as the runout of the spindle to which the end mill 3 is attached increases, the apparent diameter of the end mill 3 also increases. decrease can be reduced. As a result, even if a processing machine with greater rotational run-out is used during repair, excessive grinding of the surface can be suppressed, making it possible to repair the uneven molding surface 1b with high accuracy.

In addition, according to the present embodiment, even in the case of a molded product whose surface is decorated with a glittering pattern such as a diamond block pattern or a honeycomb pattern, it is possible to prevent the glowing pattern from becoming unclear due to repair. can be effectively resolved.

Furthermore, according to this embodiment, when a mold made in Japan is repaired overseas, it can be used as a quick and highly accurate repair method even if it is not equipped with a processing machine as highly accurate as in Japan. Can be widely deployed.

In the above-described embodiment, an example of repairing the molding surface 1b having an uneven pattern for decorating the surface of the molded product with a glow pattern has been described, but the present invention is not limited to this. It can be widely applied to the repair of molds with shaped molding surfaces.

1 mold 1a molding surface 1b damaged part 2 repair material 3, 3' end mill

Claims (6)

In the mold repair method,
A first step of filling a damaged portion on the uneven molding surface of the mold with a repair material;
The uneven molding surface is reproduced by cutting the surface raised by the repair material with a second end mill having a smaller diameter than the first end mill used when newly creating the mold. and a second step. The second step is
measuring rotational runout of a spindle to which the second end mill is attached;
2. The method of repairing a mold according to claim 1, further comprising a step of selecting a diameter of said second end mill according to said measured rotational run-out. The second step is
measuring rotational runout of a spindle to which the second end mill is attached;
2. The mold repair method according to claim 1, further comprising the step of permitting the use of said second end mill when said measured rotational run-out is equal to or less than a predetermined threshold value. 4. The mold repair method according to claim 3, further comprising the step of disallowing the use of the second end mill if the measured rotational run-out is greater than a predetermined threshold value. 5. The method of repairing a mold according to claim 1, wherein the uneven molding surface has an uneven pattern for decorating the surface of the molded article with a glitter pattern. In a mold having an uneven molding surface,
a non-repaired area where the molding surface is not repaired;
and a repair area including a portion where the damage on the molding surface is repaired,
A mold, wherein a cutter path shape on the surface of the repair area is smaller than a cutter path shape on the surface of the non-repair area.

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