JPH04309418A - Method for processing die surface and its die - Google Patents

Abstract

PURPOSE:To provide a die which can improve the surface quality of the sheet metal forming surface, and a processing method of the surface of the die, in a pressing die for forming the sheet metal of a thin steel plate. CONSTITUTION:The forming surface of a die is ground and machined at a small pitch interval by a machine tool, thereafter, a synthetic resin of an adhesive agent, etc., is applied to this surface, and subsequently, shot blasting is performed to this surface. In this case, the resin becomes a thick resin layer in a working groove part generated by the grounding work, becomes a thin resin layer in a working cut-left crest part, and at the time of shot blasting, the cut-left crest part can be eliminated effectively. That is, in the thick resin layer, energy of shot particles is absorbed and grinding is decreased, and in the cut-left crest part, grinding is increased and smoothing of the surface is quickened. Also, when this processing is performed to the contact surface to the work of a punch, a die, a pad, a blank holder, etc., of a press die, the working whose surface quality is satisfactory can be formed.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention relates to a press mold for forming a sheet metal such as a thin-walled steel plate, and a mold and a method for treating the surface of the mold, which can improve the surface quality of a workpiece forming surface. Regarding.

0002

[Prior Art] The surface of a drawing die used for sheet metal drawing is generally given a surface finish such as polishing in order to improve the surface precision of the molded product during pressing. . The surface finishing of such molds is sometimes automated and performed by mechanical work, but in the case of complex surface shapes, it is performed manually. By the way, the present applicant has previously proposed a press mold processing method and mold as shown in Japanese Patent Application No. 1-276344. The processing method for this mold is to cut the contact surface of the mold surface with the workpiece using an NC machine tool at a small pitch, and reduce the height of the uncut peaks that occur at this time to 2% of the thickness of the workpiece. This is then polished or cut to prevent defects such as distortions, undulations, etc. on the surface of the mold from being transferred to the workpiece during press molding, thereby degrading the quality of the workpiece surface. In order to remove uncut peaks that occur during cutting, shot brackets are applied directly to the surface after NC processing to smooth it. The same proposal also discloses a method of applying a solid lubricant to the surface after cutting. In other words, by applying a solid lubricant into the grinding grooves on the machined surface, the height of the uncut peaks is relatively lowered, and the workpiece surface is kept smoother during forming. It is something.

0003

[Problem to be solved by the invention] However, as mentioned above, N
When shot blasting is applied directly to the machined surface, the surface onto which shot particles are sprayed tends to be ground uniformly regardless of whether it is concave or convex, so the uncut peaks are parallel to the sprayed downstream side. There was a problem in that it exhibited a movement-like phenomenon and it was difficult to obtain a fairly smooth ground surface.

0004

[Means for Solving the Problems] In order to solve the problems, the present invention involves cutting the molding surface of a mold into small pitches using a cutter of a machine tool, applying a synthetic resin to the surface, and then applying a shot. Blasting was applied to remove the uncut peaks. Further, such treatment was applied to the contact surfaces of the punch, die, pad, blank holder, etc. of the press mold with the workpiece.

[0005]

[Operation] By applying synthetic resin to the machined surface, a thick resin layer is formed in concave areas such as machined grooves, and a thin resin layer is formed in convex areas such as uncut peaks. . Therefore, if shot blasting is applied from above, the thin uncut peaks of the resin layer can be effectively ground. In other words, in the processed groove portion where the resin layer is thick, the collision energy of the shot particles is absorbed by the elasticity of the resin layer, and the amount of grinding is small. Therefore, the processed surface can be smoothed extremely smoothly.

[0006]

[Embodiment] An embodiment of the mold surface treatment method and mold according to the present invention will be explained based on the attached drawings. FIG. 1 is an enlarged view of the surface of a mold for explaining the processing method, FIG. 2 is a vertical cross-sectional view of a press mold, and FIG. 3 is an explanatory view showing cutting by a machine tool. As shown in FIG. 2, the press mold 1 includes a lower die 2 equipped with a punch 4, and an upper die 3 that is vertically movable on the lower die 2. The lower die 2 is supported by cushion pins 5. A blank holder 6 is provided. Further, a bead portion 7 is provided on the upper surface of the blank holder 6. And in such a press mold 1,
When the upper die 3 is raised, the blank holder 6 is moved to the raised position by the upward biasing force of the cushion pin 5, and the sheet metal workpiece W is placed on the blank holder 6 in this state and press working is performed. That is, the upper die 3 descends, sandwiches the sheet metal work W with the blank holder 6, and continues to descend further while pushing the cushion pin 5. Then, the lower surface of the center of the sheet metal workpiece W comes into contact with the upper surface of the punch 4, and then the sheet metal workpiece W is drawn to follow the shape of the upper surface of the punch 4.

By the way, in such press working, the contact surface of the die that comes into contact with the sheet metal workpiece W is subjected to the surface treatment of the present invention. , will be explained with reference to FIG. In processing the forming surface of the punch 4, first, as shown in FIG. 3, cutting is performed with a cutter 10 using an NC machine tool or the like. That is, cutting is performed while moving the cutter 10 based on the shape data inputted in advance. For example, the illustrated pitch interval P is set to a small pitch of 2 to 4 mm width. At this time, on the processed surface,
The machining groove 11 through which the cutter 10 passed, each cutter groove 11,
Uncut mountain portions 12 are formed between the holes 11 and 11, resulting in a difference in the undulations of the uneven portions.

[0008] Therefore, the present invention attempts to effectively grind only the uncut peak portion 12 by applying a synthetic resin to this machined surface. That is, as shown in FIG. 1(A), when adhesive 13 as a synthetic resin is applied to the machined surface, the thickness of adhesive 13 that has entered the machined groove 11 and the thickness of adhesive 13 in the uncut crest 12 are It will be applied differently. In the case of the embodiment, a synthetic rubber adhesive such as Bond G10, Bond MPX, Bond MOX10 (manufactured by Konishi Co., Ltd.) is used as the adhesive 13,
This is dried and cured to form the adhesive layer 1 as shown in the figure (B).
form 3. The adhesive layer 13 is not limited to the above-mentioned adhesive as long as it can be an elastic layer that is difficult to peel off from the base material.

Next, as shown in Figure (C), shot blasting is applied from above. Such shot blasting is performed, for example, by a shot device 20 as shown in FIG. The processed shot material 24 and dust are sucked into a collection tank 27 from a vacuum hose 26, and only the dust is collected by a dust collector 28. As the shot material 24, for example, glass beads with a particle size of #300 are used, and the shot air pressure is 3 kg/cm2 with a nozzle diameter of φ5.
The shot conditions were set as follows. By this shot blasting, the uncut peaks 12 of the machined surface are effectively ground as shown in Figure (C), and the thick machined grooves 11 of the adhesive layer 13 are
In this case, since the energy of the shot particles is absorbed, smoothing of the entire surface is promoted. In addition, it is clear that the maximum height of waviness on the ground surface finished using the above method is 25μ, which is less than half of the maximum waviness height of 45μ immediately after NC processing, which is less than half of the high precision. became. This value also satisfies the current target level of 30μ or less in the case of manual finishing. The surface treatment of the mold of the present invention is applied not only to the above-mentioned punch 4 but also to surfaces that come into contact with other workpieces, such as dies, pads, blank holders, etc. In the surface-treated mold as described above, the contact surface with the workpiece is finished smoothly with high precision, so there is no distortion or deformation on the surface of the workpiece W during press processing, and the surface quality is improved. Good press working can be performed.

0010

Effects of the Invention As described above, in the mold and mold surface treatment method of the present invention, a synthetic resin is applied to the surface processed by a machine tool and shot blasting is performed, so that the resin layer formed on the processed surface is reduced. It is possible to efficiently grind only the thin part of the material. In addition, since it can replace the conventional manual work, it is effective in saving labor and shortening the working time.

[Brief explanation of drawings]

[Figure 1] Enlarged view of the mold surface to explain the treatment method of the present invention

[Figure 2] Vertical cross-sectional view of press mold

[Figure 3] Explanatory diagram showing cutting processing using a machine tool

[Figure 4]
Overall diagram of shot device

[Explanation of symbols]

(1) Press mold (11
) Machining groove (12) Uncut mountain part (
13) Adhesive (20) Shot device

Claims (2)

[Claims] Claim 1: A processing method for processing the surface of a press mold for sheet metal forming, which involves cutting the molding surface of the mold into small pitch intervals using a machine tool, and then applying a synthetic resin to the surface. A method for treating a surface of a mold, the method comprising: then performing shot blasting to remove uncut peaks on the surface. [Claim 2] In a press mold for forming sheet metal, surfaces of the mold that come into contact with workpieces such as punches, dies, pads, blank holders, etc. are subjected to the treatment according to claim 1. Characteristic press mold.