JP2711156B2 - Mold for stamping sheet metal parts - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a die for pressing a sheet metal part such as an aluminum alloy plate or a steel plate.

(Prior Art) Conventionally, a relatively large mold used for press working of a sheet metal part having a smooth surface such as an inner plate part and an outer plate part of an automobile usually forms a mold model using styrene foam. Then, after applying a resin solvent to form a hardened layer on the surface, the model is surrounded by sand, and in this state, a mold made of a mold is formed by a so-called FMC method of injecting a molten metal made of an iron-based material and burning styrene foam or the like. A material die is manufactured, and thereafter, a roughing process, a finishing process, a polishing process, and the like are sequentially performed on the surface of the material die to manufacture a desired die in consideration of springback, elongation, and the like of a sheet metal part. Then, the mold thus manufactured is usually used in a car production line or the like after performing a quality inspection or the like by pressing a sheet metal part on a trial basis using the mold.

In the manufacture of this type of mold, the contact surface of the mold that comes into contact with the sheet metal part at the time of press working prevents the sheet metal part from being distorted, scratched, etc. In order to make it easy to deform by sliding the bent portion of the sheet metal part in the press working against the contact surface of the mold, polishing is performed until the contact surface becomes a mirror surface,
In particular, in a die for pressing a sheet metal part whose surface is required to have a high degree of smoothness, such as an outer plate part of an automobile, the contact surface is carefully polished.
In the polishing process, when the contact surface of the mold has a relatively flat shape, a device for automatically performing this is being developed in recent years, but the contact surface has a relatively complicated curved surface. In the case of a shape, it is still performed manually at present.

However, since the polishing of the contact surface of the mold is performed manually as described above, the polishing requires a large amount of labor and time, which hinders the improvement of the manufacturing efficiency of the mold.

Also, in such polishing by manual work, due to differences in skill or experience of workers, etc., the shape of the contact surface of the mold may be distorted due to delicate undulation, etc. When the sheet metal part is pressed, there is a possibility that the sheet metal part is not reliably processed into a desired shape, for example, the smoothness of the sheet metal part is impaired.

And, in order to prevent the distortion of the contact surface of the mold,
Press work of sheet metal parts on a trial basis as described above,
According to the result, the contact surface of the mold is modified by polishing again. However, it is often necessary to perform the repairing operation by the polishing several times. This requires much more time for production, and thus delays the schedule of putting the mold into an automobile production line or the like.

(Problems to be Solved by the Invention) The present invention solves such inconveniences, shortens the time required for manufacturing a mold, and shortens the time required for pressing a sheet metal part using the mold. The aim is to provide a mold that can.

A contact surface of the mold that can process the sheet metal part into a desired shape without hindrance is formed by efficiently processing the mold without performing polishing by hand. The purpose is to provide.

It is another object of the present invention to provide a mold capable of holding the surface of a sheet metal part with high precision and smoothness during press working of the sheet metal part.

Further, it is an object of the present invention to provide a mold capable of improving the slipperiness of a contact surface of the mold where slippage occurs between the sheet metal part and the sheet metal part during press working of the sheet metal part and improving the durability thereof. Aim.

(Means for Solving the Problems) The inventors of the present invention have demanded extremely high precision in the shape and the smoothness of the surface by press working such as an inner plate part of an automobile, for example, as a result of various studies. In the pressing of a sheet metal part that is not to be performed, if the contact surface of the die that performs the pressing with the sheet metal part is cut into a predetermined shape at a sufficiently small pitch, irregularities generated on the contact surface due to the cutting work can be obtained. The height can be made sufficiently small. Therefore, even if the die after the cutting is used as it is, the surface of the sheet metal part is pressed to a desired shape while maintaining the smoothness of the required accuracy on the surface thereof. We obtained the knowledge that processing is possible.

And, for example, in a sheet metal part requiring relatively high precision in the shape and smoothness of the surface by press working such as an outer plate part of an automobile, the cut part of the contact surface of the mold after the above cutting work. By applying a solid lubricant, if the height of the unevenness of the contact surface of the mold is made sufficiently small with respect to the thickness of the sheet metal part, it is often used in, for example, an outer panel part of an automobile. For a sheet metal part having a thickness of 0.6 to 1.2 mm, the height from the solid lubricant applied to the cut portion of the contact surface of the mold to the tip of the uncut ridge remaining between the cut portions is equal to the height. If the thickness is set to 2% or less of the thickness of the sheet metal part, it is possible to press-process the sheet metal part into a desired shape while maintaining the smoothness of the required accuracy of the surface using the mold as it is. Possible and in particular with the contact surface of the mold The smoothness of touch and not sheet metal parts of the surface was obtained a finding that it is possible to hold with high accuracy.

Therefore, the mold of the present invention is a mold for press-working a sheet metal part having a thickness of 0.6 to 1.2 mm in order to achieve the above object, and a contact surface of the mold with the sheet metal part is formed. After forming into a predetermined shape required for press working by cutting at a small pitch with a machine tool, in a mold in which a solid lubricant is applied to a cut portion of the contact surface, the solid lubricant applied to the cut portion The height from the cutting portion to the tip of the uncut ridge portion remaining between the cut portions is set to 2% or less of the thickness of the sheet metal part.

(Operation) According to the mold of the present invention, the contact surface of the mold with the sheet metal part is cut at a small pitch by a machine tool,
The contact surface of the mold is formed on a smooth surface with sufficiently small irregularities. Further, after the cutting, the solid lubricant is applied to the contact surface of the mold so that the solid lubricant is applied to the cut portion of the contact surface, and the solid lubricant is applied between the cut portion and the solid lubricant. The height up to the tip of the uncut mountain portion remaining at the bottom becomes smaller. As a result, the height of the irregularities on the contact surface of the mold is further reduced, and a smoother contact surface is formed.

In particular, the height from the solid lubricant applied to the contact surface of the mold to the tip of the uncut ridge is set to not more than 2% of the thickness of the sheet metal part from 0.6 to 1.2 mm. The contact surface of the mold is formed smoothly with high precision. Therefore, when pressing is performed using the mold, the sheet metal part is pressed into a desired shape while maintaining the surface smoothness with high precision. Further, at the time of press working, the surface of the sheet metal part that does not contact the contact surface of the mold is hardly affected by slight unevenness of the contact surface, and a smooth state before the press work is maintained. .

Further, since the solid lubricant is applied to the contact surface of the mold, when the sheet metal part is pressed using the mold, the sliding of the sheet metal part in the portion where the solid lubricant is applied is performed. As a result, the sheet metal part is easily deformed into a desired shape, and wear of the contact surface of the mold is reduced.

(Embodiment) An embodiment of a mold according to the present invention will be described with reference to FIGS. FIG. 1 is an overall explanatory view of a press molding apparatus using a mold of the present embodiment, and FIGS. 2 to 4 are explanatory views for explaining a method of processing the mold of the present embodiment.

In FIG. 1, reference numeral 1 denotes a lower die, and 2 denotes an upper die lowered toward the lower die 1. The upper die 1 includes a die 4 which is a die on a lower surface of a ram 3.

The lower die 1 includes a punch 6 which is a die provided on a bolster 5 and a blank holder 7 which is a die externally mounted on the punch 6 so as to be able to move up and down. The blank holder 7 has a cushion pin 8. And is urged toward the upper mold 2.

In such a press forming apparatus, as shown in FIG. 1, a sheet metal part W to be subjected to press working, specifically, a 0.7 mm thick surface having a smooth surface used for an inner plate part, an outer plate part and the like of an automobile.
Is mounted on the contact surface 7a with the sheet metal part W formed on the upper surface of the blank holder 7 in a state of being in contact therewith,
In this state, the upper mold 2 is lowered toward the lower mold.

At this time, the die 4 of the upper die 2 firstly contacts the blank holder 7 and the sheet metal part W while the contact surface 4a formed on the lower surface thereof with the sheet metal part W contacts the sheet metal part W at the position of the blank holder 7. Is pressed down, whereby the central portion of the sheet metal part W comes into contact with the contact surface 6 a formed on the upper surface of the punch 6 and in contact with the sheet metal part W.

Next, the sheet metal part W is pressed between the contact surface 6a of the punch 6 and the contact surface 4a of the die 4 as the upper die 2 descends,
It is bent to conform to the shape of both contact surfaces 6a, 4a and formed into a predetermined shape. Then, after the molding, the surface of the sheet metal part W on the die 4 side is coated.

In such a press forming apparatus, the die 4 is manufactured by the above-described conventional method, and the contact surface 4a is formed in a mirror-like shape by polishing.

On the other hand, the punch 6 and the blank holder 7 are molds of the present invention manufactured by processing the contact surfaces 6a and 7a by a processing method described below.

Next, a method of processing the contact surface 6a of the punch 6 will be described with reference to FIGS.

When manufacturing the punch 6, first, the material mold 9 shown in FIG. 2 was prepared by the FMC method described above.

Next, as shown in FIGS. 2 and 3, the upper surface of the material mold 9 was cut by, for example, an NC machine tool 10 to which predetermined shape data was input to form a substantially identical shape to the contact surface 6a of the punch 6.

Specifically, in this embodiment, the tool diameter R in FIG.
Using an NC machine tool 10 equipped with a ball end mill cutter 10a of = 50φ, the cutter 10a was cut along the upper surface of the material die 9 at a pitch P = 1 mm according to the above shape data while moving the cutter 10a along the upper surface.

At this time, in FIG. 3, the cutter 10a has a pitch P
Since the upper surface of the material die 9 was cut at 1 mm, the uncut ridges 12 remained between the cut portions 11 of the material die 9 by the cutter 10a, and the height h was 0.01 to 0.04 mm.

Next, on the upper surface of the material die 9 thus cut,
As shown in FIG. 4, a punch 6 was obtained by applying a solid lubricant 15 containing molybdenum, carbon, or the like.

More specifically, as shown in FIG.
The solid lubricant 15 is injected from the lubricant application nozzle 16 to each of the cutting portions 11 while moving the 16 at the pitch P along the upper surface of the material die 9 so as to fill the cutting portions 11. , A solid lubricant 15 was applied. At this time, by appropriately controlling the injection time of the lubricant application nozzle 16 and the like, the height h ′ of the uncut ridge portion 12 from the solid lubricant 15 applied to the cut portion 11 can be adjusted to the sheet metal part. The solid lubricant 15 was applied until the thickness of W became 2% or less, that is, 0.014 mm or less, whereby the contact surface 6a of the punch 6 including the fixed lubricant 15 was formed. In this case, the height of the unevenness of the contact surface 6a, that is, the height h ′ from the solid lubricant 15 applied to each cutting portion 11 to the tip of the uncut ridge 12 is the thickness of the sheet metal part W. Since it is 2% or less, a highly accurate and smooth contact surface 6a is obtained.

When the sheet metal part W is pressed by using the punch 6, even if the sheet metal part W is either an inner plate part or an outer plate part of an automobile, the surface of the sheet metal part W is hardly formed. The sheet metal part W could be pressed into a desired shape while maintaining its smoothness with high precision without giving any distortion or damage.

Incidentally, even when the blank holder 7 is manufactured in the same manner as the punch 6, the sheet metal part W can of course be pressed without any trouble.

That is, in the press forming apparatus including the punch 6, the blank holder 7, and the die 4 manufactured as described above, the contact surfaces 6a, 7 of the punch 6 and the blank holder 7 are provided.
a is formed on a smooth surface with high precision as described above, and the contact surface 4a of the die 4 is formed in a mirror-like shape. Therefore, when the sheet metal part W was pressed, it was possible to press the sheet metal part W into a desired shape while maintaining its smoothness without substantially distorting or scratching the surface of the sheet metal part W. .

After the press working, when the surface of the sheet metal part W on the die 4 side, that is, the surface that does not come into contact with the punch 6 and the blank holder 7 is coated, the height of the unevenness of the coated surface becomes, for example, outside the automobile. It was within the range of 0.1 mm or less, which was judged as a good painted surface as a board part. This means that the contact surface 6 of the punch 6 and the blank holder 7
By applying the solid lubricant 15 until the height h ′ of the uncut ridges 12 a and 7 a becomes 2% or less of the thickness of the sheet metal part W, particularly, the die 4 side of the sheet metal part W The press work was performed while maintaining the smooth state before the press work without being affected by the unevenness due to the uncut ridges 12 of the contact surfaces 6a and 7a of the punch 6 and the blank holder 7. Is shown.

Therefore, such a punch 6 and blank holder 7
Although the contact surfaces 6a and 7a are not polished, they can be used to press not only the inner plate parts of automobiles but also the outer plate parts that require high precision and smooth surface. Can be applied.

In the punch 6 processed as shown in the above-mentioned fourth illustration, the portion of the contact surface 6a of the punch 6 where the curvature is large is such that the sheet metal part W is relatively largely bent when the sheet metal part W is pressed. This is a portion where sliding occurs with the component W (hereinafter, referred to as a sliding portion). When the slipperiness of the sliding portion is improved, the sheet metal component W becomes more slippery during press forming of the sheet metal component W, so that the sheet metal component W is easily bent along the contact surface 6a.

In the punch 6 and the like, in order to improve the slipperiness as described above, for example, a solid lubricant
Before applying 15, the uncut mountain portion of the sliding portion of the contact surface 6a
12 is polished in advance by shot blasting or the like, so that when the solid lubricant 15 is applied to each cutting portion, the uncut ridge 12 of the sliding portion is buried in the solid lubricant 15, or By polishing the uncut ridge 12 in the sliding portion of the contact surface 6a after the application of the solid lubricant 15, it is possible to further improve the slipperiness of the sliding portion.

(Effects of the Invention) As is clear from the above description, according to the die for stamping a sheet metal part of the present invention, the contact surface of the die with the sheet metal part is cut at a small pitch by a machine tool. Thereby, the contact surface of the mold can be formed into a smooth surface with sufficiently small unevenness, and further, after the cutting, the solid lubricant can be applied to a cut portion of the contact surface of the mold, The height from the applied solid lubricant to the tip of the uncut ridge, that is, the height of the unevenness of the contact surface can be further reduced to form a smoother contact surface. Therefore, the smoothness of the surface of the sheet metal part can be more reliably maintained during the press working using the mold.

In particular, for a sheet metal part having a thickness of 0.6 mm to 1.2 mm, the height from the solid lubricant applied to the contact surface of the mold to the tip of the uncut ridge is defined as 2 times the thickness of the sheet metal part. % Or less, the contact surface of the mold can be formed with high precision and smoothness. Therefore, it is possible to provide a mold that can press a sheet metal part into a desired shape while maintaining the surface smoothness with high precision.

In addition, since the step of manually polishing the contact surface of the mold with the sheet metal part can be omitted, the processing time of the mold can be significantly reduced, and the manufacturing efficiency of the mold can be improved. it can.

Further, at the time of press working, the surface of the sheet metal part that does not come into contact with the contact surface of the mold is hardly affected by slight unevenness of the contact surface of the mold, and ensures smoothness before the press working. High accuracy can be maintained. Therefore, for example, a sheet metal part such as an outer plate part of an automobile, which requires a smooth surface with high accuracy, can be pressed without any trouble.

In addition, a solid lubricant is applied to the contact surface of the mold with the sheet metal part, and the slipperiness of a portion of the contact surface at which sliding occurs with the sheet metal part is improved, so that the sheet metal part can be more reliably secured. Press working into a desired shape can be performed, and the durability of the mold can be improved.

[Brief description of the drawings]

FIG. 1 is an overall explanatory view of a press forming apparatus using the mold of the present embodiment, and FIGS. 2 to 4 are explanatory views for explaining a method of processing the mold of the present embodiment. 6,7 ... Die, 6a, 7a ... Contact surface, 10 ... Machine tool 11 ... Cutting point, 12 ... Uncut ridge, 15 ... Solid lubricant

 ──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Toshiki Takeda 1-10-1, Shinsayama, Sayama-shi, Saitama Honda Engineering Co., Ltd. (56) References JP-A-3-114620 (JP, A)

Claims (1)

(57) [Claims] 1. A mold for press-working a sheet metal part having a thickness of 0.6 to 1.2 mm, wherein a contact surface of the mold with the sheet metal part is cut at a small pitch by a machine tool to be pressed. After being formed into the required predetermined shape, in a mold in which a solid lubricant is applied to the cut portion of the contact surface, the uncut mountain portion remaining between the cut portions from the solid lubricant applied to the cut portion is formed. A mold having a height to a tip of 2% or less of a thickness of the sheet metal part.