JPH0475824A - Facing down machining method for nitriding mold - Google Patents

Abstract

PURPOSE:To facilitate a facing down work through the same method as a method to machine a mold on which nitriding treatment is not applied by executing a shot blast machining process and a facing down machining process, in order, in chamfering machining for a nitrided mold. CONSTITUTION:By injecting a polishing agent through a shot blast S against a part under the nitrided layer of the upper surface of a bottom mold D as the bottom mold D for a stamping forging mold is conveyed by a chain conveyor C, a nitrided layer T with which the upper surface of the bottom mold D is covered is cut for removal. A shot blast time is 30 minutes, and an injection time per the unit area of a nitrided surface is two sec/cm<2>. A chamfering work is applied on the bottom mold D for a stamping forging mold, the nitrided layer T is removed. In the wearing and breakage state of the blade tool of a machining center due to a facing down work, no difference therebetween is provided comparing with machining of a mold of the same material on the surface of which nitriding is not applied.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to face-down processing of a mold whose surface is nitrided [Prior Art] Conventionally, molds for forging, etc. have a cavity shape. After the wear limit is reached, it is economical to lower the surface and use it again. However, since the hardness of the nitrided layer of a mold whose surface is nitrided is extremely high, it is difficult to machine it, and although it is possible to process it using electrical processing methods, There was a problem in that it was not possible to lower the surface of the mold because manufacturing costs were high and it was not profitable.

[Problem that the invention seeks to solve]

The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a processing method that can inexpensively and easily lower the surface of a mold whose surface has been nitrided.

[Means for Solving the Problem] For the above purpose, according to the present invention, a nitriding process is performed in which a shot blasting process for removing a nitrided layer on the surface of a mold and a surface lowering process are carried out in sequence. A method for lowering the surface of a processing mold is provided.

[Function] According to the above configuration, the nitrided layer on the mold surface is ground and removed using the jetting pressure of the abrasive by shore blasting, thereby reducing the surface hardness of the mold, which makes it difficult to perform the post-process. Surface-down processing can be performed using the same method as conventional molds whose surfaces are not nitrided.

[Example] Next, an example shown in Drawing 1 of the method for lowering the surface of a nitriding mold according to the present invention will be described.

As shown in FIG. 1, the entire upper surface of the lower die of the die forging die is covered with a nitride layer T. The dimensions of the core mold are length Ll of 450 mm, width L2 of 200 mm, and height Hl of 150 mm, and the material is tool steel (J I S-3KD).
61). In addition, the thickness dimension t of the nitrided layer is 0.1 to 0.
．． It is 2mm.

FIG. 2 shows a state in which the nitride layer T on the surface of the lower mold is removed by shot blasting S, and the spray nozzle N of the shot blasting S is placed above the core upper mold onto the upper surface of the lower mold. It is arranged so as to inject the abrasive Z while swinging in the width direction of the supra-nuclear mold (direction of arrow F). The distance H3 from the injection port of the nozzle N to the upper surface of the lower mold is 200 mm.

In addition, on the lower side of the supranuclear mold, the lower mold is attached in the length direction (arrow A
A chain conveyor C is disposed for conveying in the direction).

The specifications of the shot blast S are that it is a direct pressure type, the air pressure is 4 kg/cm'', the diameter of the injection nozzle N is 6 mm, the particle size of the abrasive is 841 to 707 microns, and the product is Alundum.

The conveyance speed of the chain conveyor C is 1.5 cm/min.

According to the above configuration, while the lower die of the stamping forging die is conveyed by the chain conveyor C, when the abrasive is injected from the shot blast S onto the nitride layer T on the upper surface of the upper die, the lower die is The nitride layer T covering the upper surface is ground and removed. The spraying time of the Nyonoto Plus) S was 30 minutes, and the spraying time per unit area of the nitrided layer surface was 2 seconds/cm2.

Next, the lower die of the die forging die from which the nitrided layer had been removed in the above step was subjected to face-down processing using a machining center. The wear and damage of the cutting tool of the machining center due to surface lowering processing is as follows:
No difference was observed when a mold made of the same material was subjected to face-down processing using the machining center.

〔Effect of the invention〕

As described above, the method for lowering the surface of a nitrided mold according to the present invention involves grinding and removing the nitrided layer, which has a very high hardness, in advance using the Nyoto blasting process. It has excellent effects and can be easily processed using the same method as molds whose surfaces are not nitrided.

[Brief explanation of drawings]

FIG. 1 is a perspective view of the lower die of a forging die, and FIG. 2 is a perspective view of the nitride layer of the lower die of the forging die being ground and removed by shot blasting. In the figure, C is a chain conveyor, D is a lower die, T is a nitride layer,
Figure 1: S stands for shot blast, N stands for nozzle.

Claims (1)

[Claims] A method for lowering the surface of a nitriding mold, characterized in that a shot blasting process and a surface lowering process are sequentially performed in the surface lowering of the nitriding mold.