JP5642403B2 - Molding method and molded body of plate workpiece - Google Patents

Description

  The present invention relates to a method for forming a plate-shaped workpiece and a molded body.

  Conventionally, an outer plate or the like applied to a fuselage portion of a commercial aircraft has been made lighter by using an aluminum alloy plate, and has been subjected to thickness reduction processing for further weight reduction. And the outer plate | board used as the fuselage | body shape of an aircraft is shape | molded by the shape with a predetermined curvature, and is generally shape | molded by the method of carrying out the thickness reduction process by chemical milling after press-bending a flat plate. Moreover, as another shaping | molding method, there exists the method currently disclosed by patent document 1, 2, for example.

Patent Document 1 describes a method of performing a thinning process by machining after being molded in a flat plate state.
Patent Document 2 discloses a method of forming a plate-like workpiece by projecting a shot material onto the plate-like workpiece to give a predetermined curvature, and the plate-like workpiece before forming to give a predetermined curvature. Includes a step of performing a pre-processing by a plate thickness processing necessary to function as a product after forming, and a step of projecting a shot material onto a plate-shaped workpiece subjected to the pre-processing to give a predetermined curvature. A method has been proposed.

Special table 2007-508952 gazette Japanese Patent Laid-Open No. 2003-25021

However, in the conventional general molding method, chemical milling after press-bending a flat plate has a problem that processing time is long and industrial waste such as processing solution is generated.
Moreover, in patent document 1, in order to machine the outer plate | board which has a curvature, it was necessary to use a ball end mill, and the malfunction that processing efficiency fell occurred.
Further, in Patent Document 2, it is a method of projecting a shot material to form, and it is difficult to give reproducibility to processing accuracy, and correction processing is necessary.
Therefore, there is a need for a molding method that does not have the problems described above, and there is room for improvement in that respect.

The present invention has been made in view of the above-described problems, and provides a method for forming a plate-like workpiece and a molded body that can improve the processing efficiency and suppress the generation of industrial waste. With the goal.
Another object of the present invention is to provide a method for forming a plate-like workpiece and a molded body that can provide reproducibility with excellent forming accuracy.

In order to achieve the above object, in the method for forming a plate-like workpiece according to the present invention, a step of providing a plurality of recesses at a predetermined interval in the surface direction on the concave surface side of the plate-like workpiece, and a plate shape by pressing or roll bending. a step of bending the workpiece from one side toward the other surface, in a shape corresponding to the recess, and a shim Young's modulus is smaller than the plate workpiece, possess the steps of inserting into the recess, the shim is inserted A sheet-like protective material is disposed on the concave surface of the plate-like workpiece .

  Further, the molded body according to the present invention is characterized by being manufactured by the above-described method for molding a plate-like workpiece.

In the present invention, since the thinning process in which the concave portions are provided at predetermined intervals in the surface direction on the concave surface side of the plate-like workpiece can be performed in a flat plate state, a machine using an end mill in a normal three-axis machining apparatus Processing becomes possible. Moreover, since a large-diameter end mill can be used, the machining time can be shortened and the machining efficiency can be improved.
In addition, because the plate-shaped workpiece with reduced thickness is bent using a press or roll bending machine, it has excellent reproducibility of molding accuracy and correction compared to the conventional method of projecting shot material. No processing is required, and the molding time can be shortened.
Furthermore, since it is reduced by machining, there is no waste of processing solution as in the case of chemical milling, and chips generated by end mill cutting can be reused as scrap. There is an advantage that generation can be suppressed.

Moreover, it is preferable that the method for forming a plate-like workpiece according to the present invention includes a step of inserting a shim having a shape corresponding to the recess and having a Young's modulus smaller than that of the plate-like workpiece into the recess.
In the present invention, by inserting a shim having a Young's modulus smaller than that of the plate-like workpiece into the recess provided in the plate-like workpiece, the shim follows the bending of the plate-like workpiece at the time of bending, so that it is bent by elastic deformation. It is possible to increase the bending radius after the workpiece is formed. Therefore, the bending radius at the thinned portion that forms the concave portion approaches the bending radius of the general portion that is not the concave portion, so there is no difference in the bending shape between the thinned portion and the general portion, and there is no need to bend into a polygonal shape. A concave shape can be obtained.

Further, in the present invention, when a plate-shaped workpiece is bent, the shim's elastic deformation is absorbed by the shim's minus tolerance with respect to the recess, so that the adhesion between the shim and the recess is improved. Even if it exists, it can prevent that a shim remove | deviates from a recessed part.

In the method for forming a plate-like workpiece according to the present invention, the shim preferably has a Young's modulus lower than that of the workpiece, and more preferably a bakelite having a Young's modulus of 7 to 10 GPa.
In the present invention, by using a shim made of bakelite having a Young's modulus of 7 to 10 GPa, better adhesion performance with respect to the recess can be obtained. That is, it is possible to suppress problems such that the shim is less bent and the followability to the recess is deteriorated and the adhesion is deteriorated, or on the contrary, the shim is excessively bent and escapes from the recess.

In the method for forming a plate-like workpiece according to the present invention, it is preferable that the recess is formed in a step shape.
In the present invention, by providing the shim with a step corresponding to the stepped stepped portion of the recess, the adhesion at the stepped portion can be further enhanced, the followability can be improved, and the plate-like workpiece Can be bent smoothly.

According to the plate-shaped workpiece forming method and the molded body of the present invention, the thinning process for providing the concave portion in the plate-shaped workpiece can be performed in a flat plate state, and therefore a machine using an end mill in a normal three-axis machining apparatus Since the processing becomes possible, the processing efficiency can be improved and the generation of industrial waste can be suppressed as compared with the thickness reduction processing by chemical milling.
Further, since bending is mechanical processing by press or roll bending, there is an advantage that reproducibility with excellent molding accuracy can be provided.

It is sectional drawing which shows the thickness reduction process state of the plate-shaped workpiece | work by the 1st Embodiment of this invention. It is sectional drawing which shows the state which gave the bending process to the plate-shaped workpiece | work shown in FIG. It is a fragmentary sectional view which shows the bending process process by a press. It is sectional drawing which shows the thickness reduction process state of the plate-shaped workpiece | work by 2nd Embodiment. It is sectional drawing which shows the state which gave the bending process to the plate-shaped workpiece | work shown in FIG. It is a fragmentary sectional view which shows the bending process process of the plate-shaped workpiece | work by 3rd Embodiment. It is a partial expanded sectional view of the recessed part of the plate-shaped workpiece | work shown in FIG. It is a graph which shows the relationship between the Young's modulus and curvature of the shim by an Example.

  Hereinafter, a method for forming a plate-like workpiece and a formed body according to embodiments of the present invention will be described with reference to the drawings. This embodiment shows one aspect of the present invention, and does not limit the present invention, and can be arbitrarily changed within the scope of the technical idea of the present invention. Moreover, in the following drawings, in order to make each structure easy to understand, an actual structure and a scale, a number, and the like in each structure are different.

(First embodiment)
Reference numeral 1 shown in FIG. 1 and FIG. 2 is a part of a cylindrical outer plate (hereinafter referred to as “plate-like workpiece 1”) used for, for example, an aircraft fuselage, and is molded according to the first embodiment. It is an object to be bent to a predetermined curvature by a method. The plate workpiece 1 is made of an aluminum alloy. The plate-like workpiece 1 corresponds to the “molded body” of the present invention.
Here, in the plate-like workpiece 1 shown in FIGS. 1 to 3, the upper side is a concave surface 1a and the lower side is a convex surface 1b.

The forming method of the plate-like workpiece 1 includes a first step in which a plurality of pockets 11 (concave portions) are provided at a predetermined interval in the surface direction on the concave surface 1a side of the plate-like workpiece 1 to reduce the thickness, and a plate by press A second step of bending the shaped work 1 from the convex surface 1b (one surface) to the concave surface 1a (the other surface).
The pocket 11 is disposed at a predetermined position on the concave surface 1a of the plate-like workpiece 1 and has, for example, a substantially square shape in plan view, and is formed to have an appropriate thickness dimension by the first step of the above-described thinning process. .

Next, the method for forming the plate workpiece 1 will be described more specifically.
First, in the first step, a predetermined position (thickness dimension) is set at a predetermined position using, for example, an ordinary triaxial machining apparatus equipped with an end mill for the flat plate-like workpiece 1 shown in FIG. The thinning process is performed to form a plurality of pockets 11.

  Subsequently, in the second step, as shown in FIG. 3, the plate-like workpiece 1 subjected to the thickness reduction processing in the first step is placed on the lower mold 21 of the press machine 2. Here, the press machine 2 has a pair of upper and lower molds (lower mold 21 and upper mold 22), and the upper mold 22 moves up and down with respect to the fixed lower mold 21. Yes. The width dimension of the lower mold 21 and the upper mold 22 is larger than the width dimension of the plate-like workpiece 1. The lower mold 21 is provided with an opening recess 21 a at a position corresponding to the upper mold 22.

  Then, the upper die 22 is pushed into the lower die 21 side against the plate-like workpiece 1, and the plate-like workpiece 1 placed on the lower die 21 is locally pressed to bend. Then, the plate-like plate-like workpiece 1 is subjected to cylindrical bending by sequentially repeating the pressing operation by the upper mold 22 while feeding it in the circumferential direction (arrow X direction in FIG. 3) for bending the plate-like workpiece 1. And a smooth concave surface 1a can be formed.

  As a specific example of such a forming method, a plate-like workpiece 1 having a width dimension of 2 m, a length dimension of 6 m, and a plate thickness dimension t1 of about 4 mm and a 2024-T3 aluminum alloy is used locally. The thickness of the first step is reduced by machining using an end mill with a tool diameter of 50 mm so that the thickness dimension t2 becomes 2 mm, and then the bending radius is obtained by bending using the press machine 2 as the second machining step by step. It can be bent into a cylindrical shape of about 3 m.

  In the plate-like workpiece forming method and the molded body according to the first embodiment described above, the thinning process in which the pockets 11 are provided at predetermined intervals in the surface direction on the concave surface 1a side of the plate-like workpiece 1 is in the state of a flat plate. Therefore, it is possible to perform machining using an end mill with a normal three-axis machining apparatus. Moreover, since a large-diameter end mill can be used, the machining time can be shortened and the machining efficiency can be improved.

In addition, since the plate-like workpiece 1 subjected to the thinning process is bent using the press machine 2, it is excellent in reproducibility of molding accuracy compared to the conventional method of projecting shot material, and no correction process is required. Thus, the molding time can be shortened.
Furthermore, since it is reduced by machining, there is no waste of processing solution as in the case of chemical milling, and chips generated by end mill cutting can be reused as scrap. There is an advantage that generation can be suppressed.

  Next, other embodiments of the plate-like workpiece molding method and molded body according to the present invention will be described with reference to the accompanying drawings. However, the same or similar members and parts as those of the first embodiment described above The description is omitted using the same reference numerals, and a configuration different from the embodiment will be described.

(Second Embodiment)
As shown in FIGS. 4 and 5, the plate-like workpiece molding method and molded body according to the second embodiment are provided by the thinning process after the first step in the first embodiment described above. This includes a step of inserting a shim 3 having a shape corresponding to the pocket 11 and having a Young's modulus smaller than that of the plate-like workpiece 1. The bending process in the second step is a method using the press machine 2 (see FIG. 3) as in the above-described embodiment, and thus detailed description thereof is omitted here.

The shim 3 is preferably a material having high adhesion to the pocket 11 to be fitted and easily adaptable, and is preferably a member having a Young's modulus of 5 to 25 GPa, more preferably 7 to 10 GPa.
The shim 3 is provided with a minus tolerance slightly smaller than the inner space of the pocket 11 and is loosely fitted to the pocket 11. That is, the shim 3 fitted in the pocket 11 is in a state in which sliding occurs due to elastic deformation in accordance with the force received from the outside while in close contact with the pocket 11.

  In the second embodiment, by providing the shim 3, the first plate thickness dimension t <b> 1 (FIG. 4) of the general portion that is not subjected to the thinning process and the second plate of the thinned portion provided with the pocket 11. The bending process of the second step can be performed in a state where the difference (plate thickness dimension difference Δt) from the thickness dimension t2 (FIG. 4) is eliminated.

Specifically, by inserting a shim 3 having a smaller Young's modulus (for example, 5 to 25 GPa as described above) into the pocket 11 provided in the plate-like work 1, the shim 3 is plate-like during bending. Since it bends by elastic deformation following the bending of the workpiece 1, the bending radius of the plate-like workpiece 1 after molding can be increased.
Therefore, since the bending radius at the thinned portion forming the pocket 11 approaches the bending radius of the general portion that is not the pocket 11, there is no difference in the bent shape between the thinned portion and the general portion, resulting in a polygonal shape (large plate thickness dimension). It is possible to obtain a smooth concave surface shape without bending in a bending that forms a polygon having a general portion as a vertex.

  Further, since the shim 3 is loosely fitted to the pocket 11, the elastic deformation of the shim 3 is absorbed by the minus tolerance of the shim 3 with respect to the pocket 11 when the plate-like workpiece 1 is bent. Therefore, the shim 3 can be prevented from being detached from the pocket 11 even during bending.

  In addition, by using a bakelite having a Young's modulus of 7 to 10 GPa as described above, better adhesion performance can be obtained.

  In addition, when the Young's modulus of the shim 3 is 25 GPa or more, the elastic deformation of the shim 3 is small, the bending is small, the followability of the shim 3 to the bending of the pocket 11 is deteriorated, and a gap is generated between the two. In addition, the adhesion becomes low. On the other hand, when the Young's modulus of the shim 3 is less than 5 GPa, the shim 3 is bent too much, and the effect of suppressing the polygonal shape cannot be expected.

(Third embodiment)
As shown in FIGS. 6 and 7, the shape of the plate-like workpiece and the molded body according to the third embodiment are different from the shape of the pocket 11 and the shim 3 of the molding method according to the second embodiment described above. In this method, a thinning process is performed to form stepped portions 11a in the corners of the pockets 11 of the plate-like workpiece 1 at the corners (in this embodiment, one step), and the stepped portions 3a corresponding to the stepped portions 11a. The shim 3 having the above is fitted into the pocket 11. In addition, a sheet-like protective material 4 made of urethane rubber or the like is disposed on the concave surface 1 a of the plate-like workpiece 1 in a state where the shim 3 is fitted in the pocket 11 subjected to the thinning process.
Note that the bending process in the second step is a method using the press machine 2 in the same manner as in the above-described embodiment, and a detailed description thereof will be omitted here.

In this case, the followability of the step portion 3a of the shim 3 is enhanced by the step portion 11a of the pocket 11, the adhesion at the step portion can be further improved, and the plate-like workpiece 1 can be bent smoothly.
Note that the protective material 4 is merely placed on the concave surface 1a, and has a stopper function to prevent the shim 3 that bends during bending from protruding from the pocket 11.

  Next, test examples performed to support the effects of the plate-like workpiece forming method and the formed body according to the second and third embodiments described above will be described below.

  In this example, the curvature of the plate-like workpiece by bending was confirmed when a shim made of bakelite was fitted in the pocket. Specifically, FEM analysis is used to create a model of a plate-like workpiece and shim, and the plate-like workpiece is bent and analyzed under the following conditions with the shim fitted in a pocket of a predetermined shape and size. The curvature of the plate workpiece was obtained by changing the Young's modulus for each shim. In addition, it can bend efficiently, so that the value of the curvature obtained by analysis is large.

As analysis conditions, the first thickness t1 of the plate-like workpiece 1 is 6.87 mm, the second thickness t2 is 2.51 mm, and the plate-like workpiece 1 has a Young's modulus of 72 Pa and a Poisson's ratio of 0.33. And an elastic-plastic body having a density of 2.77 g / cm ³ and a yield stress of 324 MPa. The density of shim 3 was 1.32 g / cm ³ . Further, bending conditions were such that the mold and the raw material, the friction coefficient between the raw materials was 0.2, the molding speed (feed speed) was 10 mm / sec, and the feed stroke was about 8.9 mm.

  As shown in FIG. 8, according to this analysis result, it can be confirmed that the curvature is large when the Young's modulus of the shim is 7 to 10 GPa. For comparison, the case where there is no thinning process (solid material) is also shown.

As mentioned above, although the shaping | molding method of the plate-shaped workpiece and embodiment of a molded object by this invention were demonstrated, this invention is not limited to said embodiment, It can change suitably in the range which does not deviate from the meaning. is there.
For example, in the present embodiment, the press machine 2 is employed for the bending process in the second step, but the present invention is not limited to this, and a bending process using a roll bending machine may be used.

  Further, in this embodiment, bakelite is adopted as the shim 3, but it is not limited to this member. Examples of other members include epoxy resin, unsaturated polyester, and the like, and glass fiber. It may be a member filled with.

The shim 3 may be temporarily fixed to the pocket 11 with a double-sided tape or the like for the purpose of preventing the drop off. The point is that the shim 3 loosely fitted in the pocket 11 may slip within the tolerance range and be in a state where it can be elastically deformed by bending.
Further, in the present embodiment, the pocket 11 is provided with one stepped portion 11a. However, the number of steps can be arbitrarily set, and may be two or more stepped portions 11a. For example, when the plate thickness of the plate-like workpiece 1 is large, a multi-stepped portion can be formed, and when the plate thickness is small, one step or no step can be formed.

  In addition, it is possible to appropriately replace the constituent elements in the above-described embodiments with well-known constituent elements without departing from the spirit of the present invention, and the above-described embodiments may be appropriately combined.

1 Plate-shaped workpiece (molded body)
1a Concave surface

2 Press 3 Shim 3a Step 4 Protection material 11 Pocket (recess)
11a Stepped part

Claims (5)

Providing a plurality of recesses at a predetermined interval in the surface direction of the concave side of the plate-like workpiece;
Bending the plate-shaped workpiece from one surface to the other surface by pressing or roll bending;
Inserting a shim having a shape corresponding to the recess and having a Young's modulus smaller than the plate-like workpiece into the recess;
I have a,
A method for forming a plate-like workpiece, wherein a sheet-like protective material is disposed on the concave surface of the plate-like workpiece into which the shim is inserted . The method for forming a plate-like workpiece according to claim 1, wherein the shim is loosely fitted to the recess . The shims molding method of a plate-shaped workpiece according to claim 1 or 2 Young's modulus and wherein the bakelite der Rukoto of 7～10GPa. The recess, a molding method of a plate-shaped workpiece according to any one of claims 1 to 3, wherein that you have formed stepwise. A molded body produced by the method for molding a plate-like workpiece according to any one of claims 1 to 4.

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